WSL2-Linux-Kernel/kernel/trace/bpf_trace.c

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// SPDX-License-Identifier: GPL-2.0
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
/* Copyright (c) 2011-2015 PLUMgrid, http://plumgrid.com
* Copyright (c) 2016 Facebook
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
*/
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/bpf.h>
#include <linux/bpf_perf_event.h>
bpf: Add bpf_snprintf_btf helper A helper is added to support tracing kernel type information in BPF using the BPF Type Format (BTF). Its signature is long bpf_snprintf_btf(char *str, u32 str_size, struct btf_ptr *ptr, u32 btf_ptr_size, u64 flags); struct btf_ptr * specifies - a pointer to the data to be traced - the BTF id of the type of data pointed to - a flags field is provided for future use; these flags are not to be confused with the BTF_F_* flags below that control how the btf_ptr is displayed; the flags member of the struct btf_ptr may be used to disambiguate types in kernel versus module BTF, etc; the main distinction is the flags relate to the type and information needed in identifying it; not how it is displayed. For example a BPF program with a struct sk_buff *skb could do the following: static struct btf_ptr b = { }; b.ptr = skb; b.type_id = __builtin_btf_type_id(struct sk_buff, 1); bpf_snprintf_btf(str, sizeof(str), &b, sizeof(b), 0, 0); Default output looks like this: (struct sk_buff){ .transport_header = (__u16)65535, .mac_header = (__u16)65535, .end = (sk_buff_data_t)192, .head = (unsigned char *)0x000000007524fd8b, .data = (unsigned char *)0x000000007524fd8b, .truesize = (unsigned int)768, .users = (refcount_t){ .refs = (atomic_t){ .counter = (int)1, }, }, } Flags modifying display are as follows: - BTF_F_COMPACT: no formatting around type information - BTF_F_NONAME: no struct/union member names/types - BTF_F_PTR_RAW: show raw (unobfuscated) pointer values; equivalent to %px. - BTF_F_ZERO: show zero-valued struct/union members; they are not displayed by default Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/1601292670-1616-4-git-send-email-alan.maguire@oracle.com
2020-09-28 14:31:05 +03:00
#include <linux/btf.h>
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
#include <linux/filter.h>
#include <linux/uaccess.h>
#include <linux/ctype.h>
#include <linux/kprobes.h>
#include <linux/spinlock.h>
#include <linux/syscalls.h>
#include <linux/error-injection.h>
#include <linux/btf_ids.h>
bpf: Add bpf_snprintf_btf helper A helper is added to support tracing kernel type information in BPF using the BPF Type Format (BTF). Its signature is long bpf_snprintf_btf(char *str, u32 str_size, struct btf_ptr *ptr, u32 btf_ptr_size, u64 flags); struct btf_ptr * specifies - a pointer to the data to be traced - the BTF id of the type of data pointed to - a flags field is provided for future use; these flags are not to be confused with the BTF_F_* flags below that control how the btf_ptr is displayed; the flags member of the struct btf_ptr may be used to disambiguate types in kernel versus module BTF, etc; the main distinction is the flags relate to the type and information needed in identifying it; not how it is displayed. For example a BPF program with a struct sk_buff *skb could do the following: static struct btf_ptr b = { }; b.ptr = skb; b.type_id = __builtin_btf_type_id(struct sk_buff, 1); bpf_snprintf_btf(str, sizeof(str), &b, sizeof(b), 0, 0); Default output looks like this: (struct sk_buff){ .transport_header = (__u16)65535, .mac_header = (__u16)65535, .end = (sk_buff_data_t)192, .head = (unsigned char *)0x000000007524fd8b, .data = (unsigned char *)0x000000007524fd8b, .truesize = (unsigned int)768, .users = (refcount_t){ .refs = (atomic_t){ .counter = (int)1, }, }, } Flags modifying display are as follows: - BTF_F_COMPACT: no formatting around type information - BTF_F_NONAME: no struct/union member names/types - BTF_F_PTR_RAW: show raw (unobfuscated) pointer values; equivalent to %px. - BTF_F_ZERO: show zero-valued struct/union members; they are not displayed by default Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/1601292670-1616-4-git-send-email-alan.maguire@oracle.com
2020-09-28 14:31:05 +03:00
#include <uapi/linux/bpf.h>
#include <uapi/linux/btf.h>
#include <asm/tlb.h>
#include "trace_probe.h"
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
#include "trace.h"
#define CREATE_TRACE_POINTS
#include "bpf_trace.h"
#define bpf_event_rcu_dereference(p) \
rcu_dereference_protected(p, lockdep_is_held(&bpf_event_mutex))
#ifdef CONFIG_MODULES
struct bpf_trace_module {
struct module *module;
struct list_head list;
};
static LIST_HEAD(bpf_trace_modules);
static DEFINE_MUTEX(bpf_module_mutex);
static struct bpf_raw_event_map *bpf_get_raw_tracepoint_module(const char *name)
{
struct bpf_raw_event_map *btp, *ret = NULL;
struct bpf_trace_module *btm;
unsigned int i;
mutex_lock(&bpf_module_mutex);
list_for_each_entry(btm, &bpf_trace_modules, list) {
for (i = 0; i < btm->module->num_bpf_raw_events; ++i) {
btp = &btm->module->bpf_raw_events[i];
if (!strcmp(btp->tp->name, name)) {
if (try_module_get(btm->module))
ret = btp;
goto out;
}
}
}
out:
mutex_unlock(&bpf_module_mutex);
return ret;
}
#else
static struct bpf_raw_event_map *bpf_get_raw_tracepoint_module(const char *name)
{
return NULL;
}
#endif /* CONFIG_MODULES */
u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
u64 bpf_get_stack(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
static int bpf_btf_printf_prepare(struct btf_ptr *ptr, u32 btf_ptr_size,
u64 flags, const struct btf **btf,
s32 *btf_id);
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
/**
* trace_call_bpf - invoke BPF program
* @call: tracepoint event
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
* @ctx: opaque context pointer
*
* kprobe handlers execute BPF programs via this helper.
* Can be used from static tracepoints in the future.
*
* Return: BPF programs always return an integer which is interpreted by
* kprobe handler as:
* 0 - return from kprobe (event is filtered out)
* 1 - store kprobe event into ring buffer
* Other values are reserved and currently alias to 1
*/
unsigned int trace_call_bpf(struct trace_event_call *call, void *ctx)
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
{
unsigned int ret;
if (in_nmi()) /* not supported yet */
return 1;
cant_sleep();
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) {
/*
* since some bpf program is already running on this cpu,
* don't call into another bpf program (same or different)
* and don't send kprobe event into ring-buffer,
* so return zero here
*/
ret = 0;
goto out;
}
/*
* Instead of moving rcu_read_lock/rcu_dereference/rcu_read_unlock
* to all call sites, we did a bpf_prog_array_valid() there to check
* whether call->prog_array is empty or not, which is
* a heurisitc to speed up execution.
*
* If bpf_prog_array_valid() fetched prog_array was
* non-NULL, we go into trace_call_bpf() and do the actual
* proper rcu_dereference() under RCU lock.
* If it turns out that prog_array is NULL then, we bail out.
* For the opposite, if the bpf_prog_array_valid() fetched pointer
* was NULL, you'll skip the prog_array with the risk of missing
* out of events when it was updated in between this and the
* rcu_dereference() which is accepted risk.
*/
ret = BPF_PROG_RUN_ARRAY_CHECK(call->prog_array, ctx, BPF_PROG_RUN);
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
out:
__this_cpu_dec(bpf_prog_active);
return ret;
}
#ifdef CONFIG_BPF_KPROBE_OVERRIDE
BPF_CALL_2(bpf_override_return, struct pt_regs *, regs, unsigned long, rc)
{
regs_set_return_value(regs, rc);
override_function_with_return(regs);
return 0;
}
static const struct bpf_func_proto bpf_override_return_proto = {
.func = bpf_override_return,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_ANYTHING,
};
#endif
static __always_inline int
bpf_probe_read_user_common(void *dst, u32 size, const void __user *unsafe_ptr)
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
{
int ret;
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
ret = copy_from_user_nofault(dst, unsafe_ptr, size);
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
if (unlikely(ret < 0))
memset(dst, 0, size);
return ret;
}
BPF_CALL_3(bpf_probe_read_user, void *, dst, u32, size,
const void __user *, unsafe_ptr)
{
return bpf_probe_read_user_common(dst, size, unsafe_ptr);
}
const struct bpf_func_proto bpf_probe_read_user_proto = {
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
.func = bpf_probe_read_user,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_UNINIT_MEM,
.arg2_type = ARG_CONST_SIZE_OR_ZERO,
.arg3_type = ARG_ANYTHING,
};
static __always_inline int
bpf_probe_read_user_str_common(void *dst, u32 size,
const void __user *unsafe_ptr)
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
{
int ret;
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
ret = strncpy_from_user_nofault(dst, unsafe_ptr, size);
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
if (unlikely(ret < 0))
memset(dst, 0, size);
return ret;
}
BPF_CALL_3(bpf_probe_read_user_str, void *, dst, u32, size,
const void __user *, unsafe_ptr)
{
return bpf_probe_read_user_str_common(dst, size, unsafe_ptr);
}
const struct bpf_func_proto bpf_probe_read_user_str_proto = {
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
.func = bpf_probe_read_user_str,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_UNINIT_MEM,
.arg2_type = ARG_CONST_SIZE_OR_ZERO,
.arg3_type = ARG_ANYTHING,
};
static __always_inline int
bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr)
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
{
int ret = security_locked_down(LOCKDOWN_BPF_READ);
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
if (unlikely(ret < 0))
goto fail;
ret = copy_from_kernel_nofault(dst, unsafe_ptr, size);
if (unlikely(ret < 0))
goto fail;
return ret;
fail:
memset(dst, 0, size);
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
return ret;
}
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
BPF_CALL_3(bpf_probe_read_kernel, void *, dst, u32, size,
const void *, unsafe_ptr)
{
return bpf_probe_read_kernel_common(dst, size, unsafe_ptr);
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
}
const struct bpf_func_proto bpf_probe_read_kernel_proto = {
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
.func = bpf_probe_read_kernel,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_UNINIT_MEM,
.arg2_type = ARG_CONST_SIZE_OR_ZERO,
.arg3_type = ARG_ANYTHING,
};
static __always_inline int
bpf_probe_read_kernel_str_common(void *dst, u32 size, const void *unsafe_ptr)
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
{
int ret = security_locked_down(LOCKDOWN_BPF_READ);
if (unlikely(ret < 0))
goto fail;
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
/*
* The strncpy_from_kernel_nofault() call will likely not fill the
* entire buffer, but that's okay in this circumstance as we're probing
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
* arbitrary memory anyway similar to bpf_probe_read_*() and might
* as well probe the stack. Thus, memory is explicitly cleared
* only in error case, so that improper users ignoring return
* code altogether don't copy garbage; otherwise length of string
* is returned that can be used for bpf_perf_event_output() et al.
*/
ret = strncpy_from_kernel_nofault(dst, unsafe_ptr, size);
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
if (unlikely(ret < 0))
goto fail;
return ret;
fail:
memset(dst, 0, size);
return ret;
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
}
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
BPF_CALL_3(bpf_probe_read_kernel_str, void *, dst, u32, size,
const void *, unsafe_ptr)
{
return bpf_probe_read_kernel_str_common(dst, size, unsafe_ptr);
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
}
const struct bpf_func_proto bpf_probe_read_kernel_str_proto = {
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
.func = bpf_probe_read_kernel_str,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_UNINIT_MEM,
.arg2_type = ARG_CONST_SIZE_OR_ZERO,
.arg3_type = ARG_ANYTHING,
};
#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
BPF_CALL_3(bpf_probe_read_compat, void *, dst, u32, size,
const void *, unsafe_ptr)
{
if ((unsigned long)unsafe_ptr < TASK_SIZE) {
return bpf_probe_read_user_common(dst, size,
(__force void __user *)unsafe_ptr);
}
return bpf_probe_read_kernel_common(dst, size, unsafe_ptr);
}
static const struct bpf_func_proto bpf_probe_read_compat_proto = {
.func = bpf_probe_read_compat,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_UNINIT_MEM,
.arg2_type = ARG_CONST_SIZE_OR_ZERO,
.arg3_type = ARG_ANYTHING,
};
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
BPF_CALL_3(bpf_probe_read_compat_str, void *, dst, u32, size,
const void *, unsafe_ptr)
{
if ((unsigned long)unsafe_ptr < TASK_SIZE) {
return bpf_probe_read_user_str_common(dst, size,
(__force void __user *)unsafe_ptr);
}
return bpf_probe_read_kernel_str_common(dst, size, unsafe_ptr);
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
}
static const struct bpf_func_proto bpf_probe_read_compat_str_proto = {
.func = bpf_probe_read_compat_str,
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_UNINIT_MEM,
.arg2_type = ARG_CONST_SIZE_OR_ZERO,
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
.arg3_type = ARG_ANYTHING,
};
#endif /* CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE */
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
BPF_CALL_3(bpf_probe_write_user, void __user *, unsafe_ptr, const void *, src,
bpf: add BPF_CALL_x macros for declaring helpers This work adds BPF_CALL_<n>() macros and converts all the eBPF helper functions to use them, in a similar fashion like we do with SYSCALL_DEFINE<n>() macros that are used today. Motivation for this is to hide all the register handling and all necessary casts from the user, so that it is done automatically in the background when adding a BPF_CALL_<n>() call. This makes current helpers easier to review, eases to write future helpers, avoids getting the casting mess wrong, and allows for extending all helpers at once (f.e. build time checks, etc). It also helps detecting more easily in code reviews that unused registers are not instrumented in the code by accident, breaking compatibility with existing programs. BPF_CALL_<n>() internals are quite similar to SYSCALL_DEFINE<n>() ones with some fundamental differences, for example, for generating the actual helper function that carries all u64 regs, we need to fill unused regs, so that we always end up with 5 u64 regs as an argument. I reviewed several 0-5 generated BPF_CALL_<n>() variants of the .i results and they look all as expected. No sparse issue spotted. We let this also sit for a few days with Fengguang's kbuild test robot, and there were no issues seen. On s390, it barked on the "uses dynamic stack allocation" notice, which is an old one from bpf_perf_event_output{,_tp}() reappearing here due to the conversion to the call wrapper, just telling that the perf raw record/frag sits on stack (gcc with s390's -mwarn-dynamicstack), but that's all. Did various runtime tests and they were fine as well. All eBPF helpers are now converted to use these macros, getting rid of a good chunk of all the raw castings. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-09 03:45:31 +03:00
u32, size)
{
/*
* Ensure we're in user context which is safe for the helper to
* run. This helper has no business in a kthread.
*
* access_ok() should prevent writing to non-user memory, but in
* some situations (nommu, temporary switch, etc) access_ok() does
* not provide enough validation, hence the check on KERNEL_DS.
*
* nmi_uaccess_okay() ensures the probe is not run in an interim
* state, when the task or mm are switched. This is specifically
* required to prevent the use of temporary mm.
*/
if (unlikely(in_interrupt() ||
current->flags & (PF_KTHREAD | PF_EXITING)))
return -EPERM;
if (unlikely(uaccess_kernel()))
return -EPERM;
if (unlikely(!nmi_uaccess_okay()))
return -EPERM;
return copy_to_user_nofault(unsafe_ptr, src, size);
}
static const struct bpf_func_proto bpf_probe_write_user_proto = {
.func = bpf_probe_write_user,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_ANYTHING,
.arg2_type = ARG_PTR_TO_MEM,
.arg3_type = ARG_CONST_SIZE,
};
static const struct bpf_func_proto *bpf_get_probe_write_proto(void)
{
if (!capable(CAP_SYS_ADMIN))
return NULL;
pr_warn_ratelimited("%s[%d] is installing a program with bpf_probe_write_user helper that may corrupt user memory!",
current->comm, task_pid_nr(current));
return &bpf_probe_write_user_proto;
}
static void bpf_trace_copy_string(char *buf, void *unsafe_ptr, char fmt_ptype,
size_t bufsz)
{
void __user *user_ptr = (__force void __user *)unsafe_ptr;
buf[0] = 0;
switch (fmt_ptype) {
case 's':
#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
if ((unsigned long)unsafe_ptr < TASK_SIZE) {
strncpy_from_user_nofault(buf, user_ptr, bufsz);
break;
}
fallthrough;
#endif
case 'k':
strncpy_from_kernel_nofault(buf, unsafe_ptr, bufsz);
break;
case 'u':
strncpy_from_user_nofault(buf, user_ptr, bufsz);
break;
}
}
static DEFINE_RAW_SPINLOCK(trace_printk_lock);
#define BPF_TRACE_PRINTK_SIZE 1024
static __printf(1, 0) int bpf_do_trace_printk(const char *fmt, ...)
{
static char buf[BPF_TRACE_PRINTK_SIZE];
unsigned long flags;
va_list ap;
int ret;
raw_spin_lock_irqsave(&trace_printk_lock, flags);
va_start(ap, fmt);
ret = vsnprintf(buf, sizeof(buf), fmt, ap);
va_end(ap);
/* vsnprintf() will not append null for zero-length strings */
if (ret == 0)
buf[0] = '\0';
trace_bpf_trace_printk(buf);
raw_spin_unlock_irqrestore(&trace_printk_lock, flags);
return ret;
}
/*
* Only limited trace_printk() conversion specifiers allowed:
* %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %pB %pks %pus %s
*/
bpf: add BPF_CALL_x macros for declaring helpers This work adds BPF_CALL_<n>() macros and converts all the eBPF helper functions to use them, in a similar fashion like we do with SYSCALL_DEFINE<n>() macros that are used today. Motivation for this is to hide all the register handling and all necessary casts from the user, so that it is done automatically in the background when adding a BPF_CALL_<n>() call. This makes current helpers easier to review, eases to write future helpers, avoids getting the casting mess wrong, and allows for extending all helpers at once (f.e. build time checks, etc). It also helps detecting more easily in code reviews that unused registers are not instrumented in the code by accident, breaking compatibility with existing programs. BPF_CALL_<n>() internals are quite similar to SYSCALL_DEFINE<n>() ones with some fundamental differences, for example, for generating the actual helper function that carries all u64 regs, we need to fill unused regs, so that we always end up with 5 u64 regs as an argument. I reviewed several 0-5 generated BPF_CALL_<n>() variants of the .i results and they look all as expected. No sparse issue spotted. We let this also sit for a few days with Fengguang's kbuild test robot, and there were no issues seen. On s390, it barked on the "uses dynamic stack allocation" notice, which is an old one from bpf_perf_event_output{,_tp}() reappearing here due to the conversion to the call wrapper, just telling that the perf raw record/frag sits on stack (gcc with s390's -mwarn-dynamicstack), but that's all. Did various runtime tests and they were fine as well. All eBPF helpers are now converted to use these macros, getting rid of a good chunk of all the raw castings. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-09 03:45:31 +03:00
BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1,
u64, arg2, u64, arg3)
{
bpf: Restrict bpf_trace_printk()'s %s usage and add %pks, %pus specifier Usage of plain %s conversion specifier in bpf_trace_printk() suffers from the very same issue as bpf_probe_read{,str}() helpers, that is, it is broken on archs with overlapping address ranges. While the helpers have been addressed through work in 6ae08ae3dea2 ("bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers"), we need an option for bpf_trace_printk() as well to fix it. Similarly as with the helpers, force users to make an explicit choice by adding %pks and %pus specifier to bpf_trace_printk() which will then pick the corresponding strncpy_from_unsafe*() variant to perform the access under KERNEL_DS or USER_DS. The %pk* (kernel specifier) and %pu* (user specifier) can later also be extended for other objects aside strings that are probed and printed under tracing, and reused out of other facilities like bpf_seq_printf() or BTF based type printing. Existing behavior of %s for current users is still kept working for archs where it is not broken and therefore gated through CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE. For archs not having this property we fall-back to pick probing under KERNEL_DS as a sensible default. Fixes: 8d3b7dce8622 ("bpf: add support for %s specifier to bpf_trace_printk()") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Reported-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Brendan Gregg <brendan.d.gregg@gmail.com> Link: https://lore.kernel.org/bpf/20200515101118.6508-4-daniel@iogearbox.net
2020-05-15 13:11:18 +03:00
int i, mod[3] = {}, fmt_cnt = 0;
char buf[64], fmt_ptype;
void *unsafe_ptr = NULL;
bool str_seen = false;
/*
* bpf_check()->check_func_arg()->check_stack_boundary()
* guarantees that fmt points to bpf program stack,
* fmt_size bytes of it were initialized and fmt_size > 0
*/
if (fmt[--fmt_size] != 0)
return -EINVAL;
/* check format string for allowed specifiers */
for (i = 0; i < fmt_size; i++) {
if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i]))
return -EINVAL;
if (fmt[i] != '%')
continue;
if (fmt_cnt >= 3)
return -EINVAL;
/* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */
i++;
if (fmt[i] == 'l') {
mod[fmt_cnt]++;
i++;
bpf: Restrict bpf_trace_printk()'s %s usage and add %pks, %pus specifier Usage of plain %s conversion specifier in bpf_trace_printk() suffers from the very same issue as bpf_probe_read{,str}() helpers, that is, it is broken on archs with overlapping address ranges. While the helpers have been addressed through work in 6ae08ae3dea2 ("bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers"), we need an option for bpf_trace_printk() as well to fix it. Similarly as with the helpers, force users to make an explicit choice by adding %pks and %pus specifier to bpf_trace_printk() which will then pick the corresponding strncpy_from_unsafe*() variant to perform the access under KERNEL_DS or USER_DS. The %pk* (kernel specifier) and %pu* (user specifier) can later also be extended for other objects aside strings that are probed and printed under tracing, and reused out of other facilities like bpf_seq_printf() or BTF based type printing. Existing behavior of %s for current users is still kept working for archs where it is not broken and therefore gated through CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE. For archs not having this property we fall-back to pick probing under KERNEL_DS as a sensible default. Fixes: 8d3b7dce8622 ("bpf: add support for %s specifier to bpf_trace_printk()") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Reported-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Brendan Gregg <brendan.d.gregg@gmail.com> Link: https://lore.kernel.org/bpf/20200515101118.6508-4-daniel@iogearbox.net
2020-05-15 13:11:18 +03:00
} else if (fmt[i] == 'p') {
mod[fmt_cnt]++;
bpf: Restrict bpf_trace_printk()'s %s usage and add %pks, %pus specifier Usage of plain %s conversion specifier in bpf_trace_printk() suffers from the very same issue as bpf_probe_read{,str}() helpers, that is, it is broken on archs with overlapping address ranges. While the helpers have been addressed through work in 6ae08ae3dea2 ("bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers"), we need an option for bpf_trace_printk() as well to fix it. Similarly as with the helpers, force users to make an explicit choice by adding %pks and %pus specifier to bpf_trace_printk() which will then pick the corresponding strncpy_from_unsafe*() variant to perform the access under KERNEL_DS or USER_DS. The %pk* (kernel specifier) and %pu* (user specifier) can later also be extended for other objects aside strings that are probed and printed under tracing, and reused out of other facilities like bpf_seq_printf() or BTF based type printing. Existing behavior of %s for current users is still kept working for archs where it is not broken and therefore gated through CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE. For archs not having this property we fall-back to pick probing under KERNEL_DS as a sensible default. Fixes: 8d3b7dce8622 ("bpf: add support for %s specifier to bpf_trace_printk()") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Reported-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Brendan Gregg <brendan.d.gregg@gmail.com> Link: https://lore.kernel.org/bpf/20200515101118.6508-4-daniel@iogearbox.net
2020-05-15 13:11:18 +03:00
if ((fmt[i + 1] == 'k' ||
fmt[i + 1] == 'u') &&
fmt[i + 2] == 's') {
fmt_ptype = fmt[i + 1];
i += 2;
goto fmt_str;
}
if (fmt[i + 1] == 'B') {
i++;
goto fmt_next;
}
/* disallow any further format extensions */
if (fmt[i + 1] != 0 &&
!isspace(fmt[i + 1]) &&
!ispunct(fmt[i + 1]))
return -EINVAL;
bpf: Restrict bpf_trace_printk()'s %s usage and add %pks, %pus specifier Usage of plain %s conversion specifier in bpf_trace_printk() suffers from the very same issue as bpf_probe_read{,str}() helpers, that is, it is broken on archs with overlapping address ranges. While the helpers have been addressed through work in 6ae08ae3dea2 ("bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers"), we need an option for bpf_trace_printk() as well to fix it. Similarly as with the helpers, force users to make an explicit choice by adding %pks and %pus specifier to bpf_trace_printk() which will then pick the corresponding strncpy_from_unsafe*() variant to perform the access under KERNEL_DS or USER_DS. The %pk* (kernel specifier) and %pu* (user specifier) can later also be extended for other objects aside strings that are probed and printed under tracing, and reused out of other facilities like bpf_seq_printf() or BTF based type printing. Existing behavior of %s for current users is still kept working for archs where it is not broken and therefore gated through CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE. For archs not having this property we fall-back to pick probing under KERNEL_DS as a sensible default. Fixes: 8d3b7dce8622 ("bpf: add support for %s specifier to bpf_trace_printk()") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Reported-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Brendan Gregg <brendan.d.gregg@gmail.com> Link: https://lore.kernel.org/bpf/20200515101118.6508-4-daniel@iogearbox.net
2020-05-15 13:11:18 +03:00
goto fmt_next;
} else if (fmt[i] == 's') {
mod[fmt_cnt]++;
fmt_ptype = fmt[i];
fmt_str:
if (str_seen)
/* allow only one '%s' per fmt string */
return -EINVAL;
str_seen = true;
if (fmt[i + 1] != 0 &&
!isspace(fmt[i + 1]) &&
!ispunct(fmt[i + 1]))
return -EINVAL;
switch (fmt_cnt) {
case 0:
unsafe_ptr = (void *)(long)arg1;
arg1 = (long)buf;
break;
case 1:
unsafe_ptr = (void *)(long)arg2;
arg2 = (long)buf;
break;
case 2:
unsafe_ptr = (void *)(long)arg3;
arg3 = (long)buf;
break;
}
bpf_trace_copy_string(buf, unsafe_ptr, fmt_ptype,
sizeof(buf));
bpf: Restrict bpf_trace_printk()'s %s usage and add %pks, %pus specifier Usage of plain %s conversion specifier in bpf_trace_printk() suffers from the very same issue as bpf_probe_read{,str}() helpers, that is, it is broken on archs with overlapping address ranges. While the helpers have been addressed through work in 6ae08ae3dea2 ("bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers"), we need an option for bpf_trace_printk() as well to fix it. Similarly as with the helpers, force users to make an explicit choice by adding %pks and %pus specifier to bpf_trace_printk() which will then pick the corresponding strncpy_from_unsafe*() variant to perform the access under KERNEL_DS or USER_DS. The %pk* (kernel specifier) and %pu* (user specifier) can later also be extended for other objects aside strings that are probed and printed under tracing, and reused out of other facilities like bpf_seq_printf() or BTF based type printing. Existing behavior of %s for current users is still kept working for archs where it is not broken and therefore gated through CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE. For archs not having this property we fall-back to pick probing under KERNEL_DS as a sensible default. Fixes: 8d3b7dce8622 ("bpf: add support for %s specifier to bpf_trace_printk()") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Reported-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Brendan Gregg <brendan.d.gregg@gmail.com> Link: https://lore.kernel.org/bpf/20200515101118.6508-4-daniel@iogearbox.net
2020-05-15 13:11:18 +03:00
goto fmt_next;
}
if (fmt[i] == 'l') {
mod[fmt_cnt]++;
i++;
}
if (fmt[i] != 'i' && fmt[i] != 'd' &&
fmt[i] != 'u' && fmt[i] != 'x')
return -EINVAL;
bpf: Restrict bpf_trace_printk()'s %s usage and add %pks, %pus specifier Usage of plain %s conversion specifier in bpf_trace_printk() suffers from the very same issue as bpf_probe_read{,str}() helpers, that is, it is broken on archs with overlapping address ranges. While the helpers have been addressed through work in 6ae08ae3dea2 ("bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers"), we need an option for bpf_trace_printk() as well to fix it. Similarly as with the helpers, force users to make an explicit choice by adding %pks and %pus specifier to bpf_trace_printk() which will then pick the corresponding strncpy_from_unsafe*() variant to perform the access under KERNEL_DS or USER_DS. The %pk* (kernel specifier) and %pu* (user specifier) can later also be extended for other objects aside strings that are probed and printed under tracing, and reused out of other facilities like bpf_seq_printf() or BTF based type printing. Existing behavior of %s for current users is still kept working for archs where it is not broken and therefore gated through CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE. For archs not having this property we fall-back to pick probing under KERNEL_DS as a sensible default. Fixes: 8d3b7dce8622 ("bpf: add support for %s specifier to bpf_trace_printk()") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Reported-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Brendan Gregg <brendan.d.gregg@gmail.com> Link: https://lore.kernel.org/bpf/20200515101118.6508-4-daniel@iogearbox.net
2020-05-15 13:11:18 +03:00
fmt_next:
fmt_cnt++;
}
/* Horrid workaround for getting va_list handling working with different
* argument type combinations generically for 32 and 64 bit archs.
*/
#define __BPF_TP_EMIT() __BPF_ARG3_TP()
#define __BPF_TP(...) \
bpf_do_trace_printk(fmt, ##__VA_ARGS__)
#define __BPF_ARG1_TP(...) \
((mod[0] == 2 || (mod[0] == 1 && __BITS_PER_LONG == 64)) \
? __BPF_TP(arg1, ##__VA_ARGS__) \
: ((mod[0] == 1 || (mod[0] == 0 && __BITS_PER_LONG == 32)) \
? __BPF_TP((long)arg1, ##__VA_ARGS__) \
: __BPF_TP((u32)arg1, ##__VA_ARGS__)))
#define __BPF_ARG2_TP(...) \
((mod[1] == 2 || (mod[1] == 1 && __BITS_PER_LONG == 64)) \
? __BPF_ARG1_TP(arg2, ##__VA_ARGS__) \
: ((mod[1] == 1 || (mod[1] == 0 && __BITS_PER_LONG == 32)) \
? __BPF_ARG1_TP((long)arg2, ##__VA_ARGS__) \
: __BPF_ARG1_TP((u32)arg2, ##__VA_ARGS__)))
#define __BPF_ARG3_TP(...) \
((mod[2] == 2 || (mod[2] == 1 && __BITS_PER_LONG == 64)) \
? __BPF_ARG2_TP(arg3, ##__VA_ARGS__) \
: ((mod[2] == 1 || (mod[2] == 0 && __BITS_PER_LONG == 32)) \
? __BPF_ARG2_TP((long)arg3, ##__VA_ARGS__) \
: __BPF_ARG2_TP((u32)arg3, ##__VA_ARGS__)))
return __BPF_TP_EMIT();
}
static const struct bpf_func_proto bpf_trace_printk_proto = {
.func = bpf_trace_printk,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_MEM,
.arg2_type = ARG_CONST_SIZE,
};
const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
{
/*
* This program might be calling bpf_trace_printk,
* so enable the associated bpf_trace/bpf_trace_printk event.
* Repeat this each time as it is possible a user has
* disabled bpf_trace_printk events. By loading a program
* calling bpf_trace_printk() however the user has expressed
* the intent to see such events.
*/
if (trace_set_clr_event("bpf_trace", "bpf_trace_printk", 1))
pr_warn_ratelimited("could not enable bpf_trace_printk events");
return &bpf_trace_printk_proto;
}
bpf: Add bpf_seq_printf and bpf_seq_write helpers Two helpers bpf_seq_printf and bpf_seq_write, are added for writing data to the seq_file buffer. bpf_seq_printf supports common format string flag/width/type fields so at least I can get identical results for netlink and ipv6_route targets. For bpf_seq_printf and bpf_seq_write, return value -EOVERFLOW specifically indicates a write failure due to overflow, which means the object will be repeated in the next bpf invocation if object collection stays the same. Note that if the object collection is changed, depending how collection traversal is done, even if the object still in the collection, it may not be visited. For bpf_seq_printf, format %s, %p{i,I}{4,6} needs to read kernel memory. Reading kernel memory may fail in the following two cases: - invalid kernel address, or - valid kernel address but requiring a major fault If reading kernel memory failed, the %s string will be an empty string and %p{i,I}{4,6} will be all 0. Not returning error to bpf program is consistent with what bpf_trace_printk() does for now. bpf_seq_printf may return -EBUSY meaning that internal percpu buffer for memory copy of strings or other pointees is not available. Bpf program can return 1 to indicate it wants the same object to be repeated. Right now, this should not happen on no-RT kernels since migrate_disable(), which guards bpf prog call, calls preempt_disable(). Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200509175914.2476661-1-yhs@fb.com
2020-05-09 20:59:14 +03:00
#define MAX_SEQ_PRINTF_VARARGS 12
#define MAX_SEQ_PRINTF_MAX_MEMCPY 6
#define MAX_SEQ_PRINTF_STR_LEN 128
struct bpf_seq_printf_buf {
char buf[MAX_SEQ_PRINTF_MAX_MEMCPY][MAX_SEQ_PRINTF_STR_LEN];
};
static DEFINE_PER_CPU(struct bpf_seq_printf_buf, bpf_seq_printf_buf);
static DEFINE_PER_CPU(int, bpf_seq_printf_buf_used);
BPF_CALL_5(bpf_seq_printf, struct seq_file *, m, char *, fmt, u32, fmt_size,
const void *, data, u32, data_len)
{
int err = -EINVAL, fmt_cnt = 0, memcpy_cnt = 0;
int i, buf_used, copy_size, num_args;
u64 params[MAX_SEQ_PRINTF_VARARGS];
struct bpf_seq_printf_buf *bufs;
const u64 *args = data;
buf_used = this_cpu_inc_return(bpf_seq_printf_buf_used);
if (WARN_ON_ONCE(buf_used > 1)) {
err = -EBUSY;
goto out;
}
bufs = this_cpu_ptr(&bpf_seq_printf_buf);
/*
* bpf_check()->check_func_arg()->check_stack_boundary()
* guarantees that fmt points to bpf program stack,
* fmt_size bytes of it were initialized and fmt_size > 0
*/
if (fmt[--fmt_size] != 0)
goto out;
if (data_len & 7)
goto out;
for (i = 0; i < fmt_size; i++) {
if (fmt[i] == '%') {
if (fmt[i + 1] == '%')
i++;
else if (!data || !data_len)
goto out;
}
}
num_args = data_len / 8;
/* check format string for allowed specifiers */
for (i = 0; i < fmt_size; i++) {
/* only printable ascii for now. */
if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i])) {
err = -EINVAL;
goto out;
}
if (fmt[i] != '%')
continue;
if (fmt[i + 1] == '%') {
i++;
continue;
}
if (fmt_cnt >= MAX_SEQ_PRINTF_VARARGS) {
err = -E2BIG;
goto out;
}
if (fmt_cnt >= num_args) {
err = -EINVAL;
goto out;
}
/* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */
i++;
/* skip optional "[0 +-][num]" width formating field */
while (fmt[i] == '0' || fmt[i] == '+' || fmt[i] == '-' ||
fmt[i] == ' ')
i++;
if (fmt[i] >= '1' && fmt[i] <= '9') {
i++;
while (fmt[i] >= '0' && fmt[i] <= '9')
i++;
}
if (fmt[i] == 's') {
void *unsafe_ptr;
bpf: Add bpf_seq_printf and bpf_seq_write helpers Two helpers bpf_seq_printf and bpf_seq_write, are added for writing data to the seq_file buffer. bpf_seq_printf supports common format string flag/width/type fields so at least I can get identical results for netlink and ipv6_route targets. For bpf_seq_printf and bpf_seq_write, return value -EOVERFLOW specifically indicates a write failure due to overflow, which means the object will be repeated in the next bpf invocation if object collection stays the same. Note that if the object collection is changed, depending how collection traversal is done, even if the object still in the collection, it may not be visited. For bpf_seq_printf, format %s, %p{i,I}{4,6} needs to read kernel memory. Reading kernel memory may fail in the following two cases: - invalid kernel address, or - valid kernel address but requiring a major fault If reading kernel memory failed, the %s string will be an empty string and %p{i,I}{4,6} will be all 0. Not returning error to bpf program is consistent with what bpf_trace_printk() does for now. bpf_seq_printf may return -EBUSY meaning that internal percpu buffer for memory copy of strings or other pointees is not available. Bpf program can return 1 to indicate it wants the same object to be repeated. Right now, this should not happen on no-RT kernels since migrate_disable(), which guards bpf prog call, calls preempt_disable(). Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200509175914.2476661-1-yhs@fb.com
2020-05-09 20:59:14 +03:00
/* try our best to copy */
if (memcpy_cnt >= MAX_SEQ_PRINTF_MAX_MEMCPY) {
err = -E2BIG;
goto out;
}
unsafe_ptr = (void *)(long)args[fmt_cnt];
err = strncpy_from_kernel_nofault(bufs->buf[memcpy_cnt],
unsafe_ptr, MAX_SEQ_PRINTF_STR_LEN);
bpf: Add bpf_seq_printf and bpf_seq_write helpers Two helpers bpf_seq_printf and bpf_seq_write, are added for writing data to the seq_file buffer. bpf_seq_printf supports common format string flag/width/type fields so at least I can get identical results for netlink and ipv6_route targets. For bpf_seq_printf and bpf_seq_write, return value -EOVERFLOW specifically indicates a write failure due to overflow, which means the object will be repeated in the next bpf invocation if object collection stays the same. Note that if the object collection is changed, depending how collection traversal is done, even if the object still in the collection, it may not be visited. For bpf_seq_printf, format %s, %p{i,I}{4,6} needs to read kernel memory. Reading kernel memory may fail in the following two cases: - invalid kernel address, or - valid kernel address but requiring a major fault If reading kernel memory failed, the %s string will be an empty string and %p{i,I}{4,6} will be all 0. Not returning error to bpf program is consistent with what bpf_trace_printk() does for now. bpf_seq_printf may return -EBUSY meaning that internal percpu buffer for memory copy of strings or other pointees is not available. Bpf program can return 1 to indicate it wants the same object to be repeated. Right now, this should not happen on no-RT kernels since migrate_disable(), which guards bpf prog call, calls preempt_disable(). Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200509175914.2476661-1-yhs@fb.com
2020-05-09 20:59:14 +03:00
if (err < 0)
bufs->buf[memcpy_cnt][0] = '\0';
params[fmt_cnt] = (u64)(long)bufs->buf[memcpy_cnt];
fmt_cnt++;
memcpy_cnt++;
continue;
}
if (fmt[i] == 'p') {
if (fmt[i + 1] == 0 ||
fmt[i + 1] == 'K' ||
fmt[i + 1] == 'x' ||
fmt[i + 1] == 'B') {
bpf: Add bpf_seq_printf and bpf_seq_write helpers Two helpers bpf_seq_printf and bpf_seq_write, are added for writing data to the seq_file buffer. bpf_seq_printf supports common format string flag/width/type fields so at least I can get identical results for netlink and ipv6_route targets. For bpf_seq_printf and bpf_seq_write, return value -EOVERFLOW specifically indicates a write failure due to overflow, which means the object will be repeated in the next bpf invocation if object collection stays the same. Note that if the object collection is changed, depending how collection traversal is done, even if the object still in the collection, it may not be visited. For bpf_seq_printf, format %s, %p{i,I}{4,6} needs to read kernel memory. Reading kernel memory may fail in the following two cases: - invalid kernel address, or - valid kernel address but requiring a major fault If reading kernel memory failed, the %s string will be an empty string and %p{i,I}{4,6} will be all 0. Not returning error to bpf program is consistent with what bpf_trace_printk() does for now. bpf_seq_printf may return -EBUSY meaning that internal percpu buffer for memory copy of strings or other pointees is not available. Bpf program can return 1 to indicate it wants the same object to be repeated. Right now, this should not happen on no-RT kernels since migrate_disable(), which guards bpf prog call, calls preempt_disable(). Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200509175914.2476661-1-yhs@fb.com
2020-05-09 20:59:14 +03:00
/* just kernel pointers */
params[fmt_cnt] = args[fmt_cnt];
fmt_cnt++;
continue;
}
/* only support "%pI4", "%pi4", "%pI6" and "%pi6". */
if (fmt[i + 1] != 'i' && fmt[i + 1] != 'I') {
err = -EINVAL;
goto out;
}
if (fmt[i + 2] != '4' && fmt[i + 2] != '6') {
err = -EINVAL;
goto out;
}
if (memcpy_cnt >= MAX_SEQ_PRINTF_MAX_MEMCPY) {
err = -E2BIG;
goto out;
}
copy_size = (fmt[i + 2] == '4') ? 4 : 16;
err = copy_from_kernel_nofault(bufs->buf[memcpy_cnt],
bpf: Add bpf_seq_printf and bpf_seq_write helpers Two helpers bpf_seq_printf and bpf_seq_write, are added for writing data to the seq_file buffer. bpf_seq_printf supports common format string flag/width/type fields so at least I can get identical results for netlink and ipv6_route targets. For bpf_seq_printf and bpf_seq_write, return value -EOVERFLOW specifically indicates a write failure due to overflow, which means the object will be repeated in the next bpf invocation if object collection stays the same. Note that if the object collection is changed, depending how collection traversal is done, even if the object still in the collection, it may not be visited. For bpf_seq_printf, format %s, %p{i,I}{4,6} needs to read kernel memory. Reading kernel memory may fail in the following two cases: - invalid kernel address, or - valid kernel address but requiring a major fault If reading kernel memory failed, the %s string will be an empty string and %p{i,I}{4,6} will be all 0. Not returning error to bpf program is consistent with what bpf_trace_printk() does for now. bpf_seq_printf may return -EBUSY meaning that internal percpu buffer for memory copy of strings or other pointees is not available. Bpf program can return 1 to indicate it wants the same object to be repeated. Right now, this should not happen on no-RT kernels since migrate_disable(), which guards bpf prog call, calls preempt_disable(). Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200509175914.2476661-1-yhs@fb.com
2020-05-09 20:59:14 +03:00
(void *) (long) args[fmt_cnt],
copy_size);
if (err < 0)
memset(bufs->buf[memcpy_cnt], 0, copy_size);
params[fmt_cnt] = (u64)(long)bufs->buf[memcpy_cnt];
i += 2;
fmt_cnt++;
memcpy_cnt++;
continue;
}
if (fmt[i] == 'l') {
i++;
if (fmt[i] == 'l')
i++;
}
if (fmt[i] != 'i' && fmt[i] != 'd' &&
fmt[i] != 'u' && fmt[i] != 'x' &&
fmt[i] != 'X') {
bpf: Add bpf_seq_printf and bpf_seq_write helpers Two helpers bpf_seq_printf and bpf_seq_write, are added for writing data to the seq_file buffer. bpf_seq_printf supports common format string flag/width/type fields so at least I can get identical results for netlink and ipv6_route targets. For bpf_seq_printf and bpf_seq_write, return value -EOVERFLOW specifically indicates a write failure due to overflow, which means the object will be repeated in the next bpf invocation if object collection stays the same. Note that if the object collection is changed, depending how collection traversal is done, even if the object still in the collection, it may not be visited. For bpf_seq_printf, format %s, %p{i,I}{4,6} needs to read kernel memory. Reading kernel memory may fail in the following two cases: - invalid kernel address, or - valid kernel address but requiring a major fault If reading kernel memory failed, the %s string will be an empty string and %p{i,I}{4,6} will be all 0. Not returning error to bpf program is consistent with what bpf_trace_printk() does for now. bpf_seq_printf may return -EBUSY meaning that internal percpu buffer for memory copy of strings or other pointees is not available. Bpf program can return 1 to indicate it wants the same object to be repeated. Right now, this should not happen on no-RT kernels since migrate_disable(), which guards bpf prog call, calls preempt_disable(). Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200509175914.2476661-1-yhs@fb.com
2020-05-09 20:59:14 +03:00
err = -EINVAL;
goto out;
}
params[fmt_cnt] = args[fmt_cnt];
fmt_cnt++;
}
/* Maximumly we can have MAX_SEQ_PRINTF_VARARGS parameter, just give
* all of them to seq_printf().
*/
seq_printf(m, fmt, params[0], params[1], params[2], params[3],
params[4], params[5], params[6], params[7], params[8],
params[9], params[10], params[11]);
err = seq_has_overflowed(m) ? -EOVERFLOW : 0;
out:
this_cpu_dec(bpf_seq_printf_buf_used);
return err;
}
BTF_ID_LIST_SINGLE(btf_seq_file_ids, struct, seq_file)
bpf: Add bpf_seq_printf and bpf_seq_write helpers Two helpers bpf_seq_printf and bpf_seq_write, are added for writing data to the seq_file buffer. bpf_seq_printf supports common format string flag/width/type fields so at least I can get identical results for netlink and ipv6_route targets. For bpf_seq_printf and bpf_seq_write, return value -EOVERFLOW specifically indicates a write failure due to overflow, which means the object will be repeated in the next bpf invocation if object collection stays the same. Note that if the object collection is changed, depending how collection traversal is done, even if the object still in the collection, it may not be visited. For bpf_seq_printf, format %s, %p{i,I}{4,6} needs to read kernel memory. Reading kernel memory may fail in the following two cases: - invalid kernel address, or - valid kernel address but requiring a major fault If reading kernel memory failed, the %s string will be an empty string and %p{i,I}{4,6} will be all 0. Not returning error to bpf program is consistent with what bpf_trace_printk() does for now. bpf_seq_printf may return -EBUSY meaning that internal percpu buffer for memory copy of strings or other pointees is not available. Bpf program can return 1 to indicate it wants the same object to be repeated. Right now, this should not happen on no-RT kernels since migrate_disable(), which guards bpf prog call, calls preempt_disable(). Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200509175914.2476661-1-yhs@fb.com
2020-05-09 20:59:14 +03:00
static const struct bpf_func_proto bpf_seq_printf_proto = {
.func = bpf_seq_printf,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_BTF_ID,
.arg1_btf_id = &btf_seq_file_ids[0],
bpf: Add bpf_seq_printf and bpf_seq_write helpers Two helpers bpf_seq_printf and bpf_seq_write, are added for writing data to the seq_file buffer. bpf_seq_printf supports common format string flag/width/type fields so at least I can get identical results for netlink and ipv6_route targets. For bpf_seq_printf and bpf_seq_write, return value -EOVERFLOW specifically indicates a write failure due to overflow, which means the object will be repeated in the next bpf invocation if object collection stays the same. Note that if the object collection is changed, depending how collection traversal is done, even if the object still in the collection, it may not be visited. For bpf_seq_printf, format %s, %p{i,I}{4,6} needs to read kernel memory. Reading kernel memory may fail in the following two cases: - invalid kernel address, or - valid kernel address but requiring a major fault If reading kernel memory failed, the %s string will be an empty string and %p{i,I}{4,6} will be all 0. Not returning error to bpf program is consistent with what bpf_trace_printk() does for now. bpf_seq_printf may return -EBUSY meaning that internal percpu buffer for memory copy of strings or other pointees is not available. Bpf program can return 1 to indicate it wants the same object to be repeated. Right now, this should not happen on no-RT kernels since migrate_disable(), which guards bpf prog call, calls preempt_disable(). Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200509175914.2476661-1-yhs@fb.com
2020-05-09 20:59:14 +03:00
.arg2_type = ARG_PTR_TO_MEM,
.arg3_type = ARG_CONST_SIZE,
.arg4_type = ARG_PTR_TO_MEM_OR_NULL,
.arg5_type = ARG_CONST_SIZE_OR_ZERO,
};
BPF_CALL_3(bpf_seq_write, struct seq_file *, m, const void *, data, u32, len)
{
return seq_write(m, data, len) ? -EOVERFLOW : 0;
}
static const struct bpf_func_proto bpf_seq_write_proto = {
.func = bpf_seq_write,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_BTF_ID,
.arg1_btf_id = &btf_seq_file_ids[0],
bpf: Add bpf_seq_printf and bpf_seq_write helpers Two helpers bpf_seq_printf and bpf_seq_write, are added for writing data to the seq_file buffer. bpf_seq_printf supports common format string flag/width/type fields so at least I can get identical results for netlink and ipv6_route targets. For bpf_seq_printf and bpf_seq_write, return value -EOVERFLOW specifically indicates a write failure due to overflow, which means the object will be repeated in the next bpf invocation if object collection stays the same. Note that if the object collection is changed, depending how collection traversal is done, even if the object still in the collection, it may not be visited. For bpf_seq_printf, format %s, %p{i,I}{4,6} needs to read kernel memory. Reading kernel memory may fail in the following two cases: - invalid kernel address, or - valid kernel address but requiring a major fault If reading kernel memory failed, the %s string will be an empty string and %p{i,I}{4,6} will be all 0. Not returning error to bpf program is consistent with what bpf_trace_printk() does for now. bpf_seq_printf may return -EBUSY meaning that internal percpu buffer for memory copy of strings or other pointees is not available. Bpf program can return 1 to indicate it wants the same object to be repeated. Right now, this should not happen on no-RT kernels since migrate_disable(), which guards bpf prog call, calls preempt_disable(). Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200509175914.2476661-1-yhs@fb.com
2020-05-09 20:59:14 +03:00
.arg2_type = ARG_PTR_TO_MEM,
.arg3_type = ARG_CONST_SIZE_OR_ZERO,
};
BPF_CALL_4(bpf_seq_printf_btf, struct seq_file *, m, struct btf_ptr *, ptr,
u32, btf_ptr_size, u64, flags)
{
const struct btf *btf;
s32 btf_id;
int ret;
ret = bpf_btf_printf_prepare(ptr, btf_ptr_size, flags, &btf, &btf_id);
if (ret)
return ret;
return btf_type_seq_show_flags(btf, btf_id, ptr->ptr, m, flags);
}
static const struct bpf_func_proto bpf_seq_printf_btf_proto = {
.func = bpf_seq_printf_btf,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_BTF_ID,
.arg1_btf_id = &btf_seq_file_ids[0],
bpf: Add bpf_seq_printf and bpf_seq_write helpers Two helpers bpf_seq_printf and bpf_seq_write, are added for writing data to the seq_file buffer. bpf_seq_printf supports common format string flag/width/type fields so at least I can get identical results for netlink and ipv6_route targets. For bpf_seq_printf and bpf_seq_write, return value -EOVERFLOW specifically indicates a write failure due to overflow, which means the object will be repeated in the next bpf invocation if object collection stays the same. Note that if the object collection is changed, depending how collection traversal is done, even if the object still in the collection, it may not be visited. For bpf_seq_printf, format %s, %p{i,I}{4,6} needs to read kernel memory. Reading kernel memory may fail in the following two cases: - invalid kernel address, or - valid kernel address but requiring a major fault If reading kernel memory failed, the %s string will be an empty string and %p{i,I}{4,6} will be all 0. Not returning error to bpf program is consistent with what bpf_trace_printk() does for now. bpf_seq_printf may return -EBUSY meaning that internal percpu buffer for memory copy of strings or other pointees is not available. Bpf program can return 1 to indicate it wants the same object to be repeated. Right now, this should not happen on no-RT kernels since migrate_disable(), which guards bpf prog call, calls preempt_disable(). Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200509175914.2476661-1-yhs@fb.com
2020-05-09 20:59:14 +03:00
.arg2_type = ARG_PTR_TO_MEM,
.arg3_type = ARG_CONST_SIZE_OR_ZERO,
.arg4_type = ARG_ANYTHING,
bpf: Add bpf_seq_printf and bpf_seq_write helpers Two helpers bpf_seq_printf and bpf_seq_write, are added for writing data to the seq_file buffer. bpf_seq_printf supports common format string flag/width/type fields so at least I can get identical results for netlink and ipv6_route targets. For bpf_seq_printf and bpf_seq_write, return value -EOVERFLOW specifically indicates a write failure due to overflow, which means the object will be repeated in the next bpf invocation if object collection stays the same. Note that if the object collection is changed, depending how collection traversal is done, even if the object still in the collection, it may not be visited. For bpf_seq_printf, format %s, %p{i,I}{4,6} needs to read kernel memory. Reading kernel memory may fail in the following two cases: - invalid kernel address, or - valid kernel address but requiring a major fault If reading kernel memory failed, the %s string will be an empty string and %p{i,I}{4,6} will be all 0. Not returning error to bpf program is consistent with what bpf_trace_printk() does for now. bpf_seq_printf may return -EBUSY meaning that internal percpu buffer for memory copy of strings or other pointees is not available. Bpf program can return 1 to indicate it wants the same object to be repeated. Right now, this should not happen on no-RT kernels since migrate_disable(), which guards bpf prog call, calls preempt_disable(). Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200509175914.2476661-1-yhs@fb.com
2020-05-09 20:59:14 +03:00
};
2017-10-05 19:19:20 +03:00
static __always_inline int
get_map_perf_counter(struct bpf_map *map, u64 flags,
u64 *value, u64 *enabled, u64 *running)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
unsigned int cpu = smp_processor_id();
u64 index = flags & BPF_F_INDEX_MASK;
bpf, maps: flush own entries on perf map release The behavior of perf event arrays are quite different from all others as they are tightly coupled to perf event fds, f.e. shown recently by commit e03e7ee34fdd ("perf/bpf: Convert perf_event_array to use struct file") to make refcounting on perf event more robust. A remaining issue that the current code still has is that since additions to the perf event array take a reference on the struct file via perf_event_get() and are only released via fput() (that cleans up the perf event eventually via perf_event_release_kernel()) when the element is either manually removed from the map from user space or automatically when the last reference on the perf event map is dropped. However, this leads us to dangling struct file's when the map gets pinned after the application owning the perf event descriptor exits, and since the struct file reference will in such case only be manually dropped or via pinned file removal, it leads to the perf event living longer than necessary, consuming needlessly resources for that time. Relations between perf event fds and bpf perf event map fds can be rather complex. F.e. maps can act as demuxers among different perf event fds that can possibly be owned by different threads and based on the index selection from the program, events get dispatched to one of the per-cpu fd endpoints. One perf event fd (or, rather a per-cpu set of them) can also live in multiple perf event maps at the same time, listening for events. Also, another requirement is that perf event fds can get closed from application side after they have been attached to the perf event map, so that on exit perf event map will take care of dropping their references eventually. Likewise, when such maps are pinned, the intended behavior is that a user application does bpf_obj_get(), puts its fds in there and on exit when fd is released, they are dropped from the map again, so the map acts rather as connector endpoint. This also makes perf event maps inherently different from program arrays as described in more detail in commit c9da161c6517 ("bpf: fix clearing on persistent program array maps"). To tackle this, map entries are marked by the map struct file that added the element to the map. And when the last reference to that map struct file is released from user space, then the tracked entries are purged from the map. This is okay, because new map struct files instances resp. frontends to the anon inode are provided via bpf_map_new_fd() that is called when we invoke bpf_obj_get_user() for retrieving a pinned map, but also when an initial instance is created via map_create(). The rest is resolved by the vfs layer automatically for us by keeping reference count on the map's struct file. Any concurrent updates on the map slot are fine as well, it just means that perf_event_fd_array_release() needs to delete less of its own entires. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-15 23:47:14 +03:00
struct bpf_event_entry *ee;
if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
return -EINVAL;
if (index == BPF_F_CURRENT_CPU)
index = cpu;
if (unlikely(index >= array->map.max_entries))
return -E2BIG;
bpf, maps: flush own entries on perf map release The behavior of perf event arrays are quite different from all others as they are tightly coupled to perf event fds, f.e. shown recently by commit e03e7ee34fdd ("perf/bpf: Convert perf_event_array to use struct file") to make refcounting on perf event more robust. A remaining issue that the current code still has is that since additions to the perf event array take a reference on the struct file via perf_event_get() and are only released via fput() (that cleans up the perf event eventually via perf_event_release_kernel()) when the element is either manually removed from the map from user space or automatically when the last reference on the perf event map is dropped. However, this leads us to dangling struct file's when the map gets pinned after the application owning the perf event descriptor exits, and since the struct file reference will in such case only be manually dropped or via pinned file removal, it leads to the perf event living longer than necessary, consuming needlessly resources for that time. Relations between perf event fds and bpf perf event map fds can be rather complex. F.e. maps can act as demuxers among different perf event fds that can possibly be owned by different threads and based on the index selection from the program, events get dispatched to one of the per-cpu fd endpoints. One perf event fd (or, rather a per-cpu set of them) can also live in multiple perf event maps at the same time, listening for events. Also, another requirement is that perf event fds can get closed from application side after they have been attached to the perf event map, so that on exit perf event map will take care of dropping their references eventually. Likewise, when such maps are pinned, the intended behavior is that a user application does bpf_obj_get(), puts its fds in there and on exit when fd is released, they are dropped from the map again, so the map acts rather as connector endpoint. This also makes perf event maps inherently different from program arrays as described in more detail in commit c9da161c6517 ("bpf: fix clearing on persistent program array maps"). To tackle this, map entries are marked by the map struct file that added the element to the map. And when the last reference to that map struct file is released from user space, then the tracked entries are purged from the map. This is okay, because new map struct files instances resp. frontends to the anon inode are provided via bpf_map_new_fd() that is called when we invoke bpf_obj_get_user() for retrieving a pinned map, but also when an initial instance is created via map_create(). The rest is resolved by the vfs layer automatically for us by keeping reference count on the map's struct file. Any concurrent updates on the map slot are fine as well, it just means that perf_event_fd_array_release() needs to delete less of its own entires. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-15 23:47:14 +03:00
ee = READ_ONCE(array->ptrs[index]);
if (!ee)
return -ENOENT;
2017-10-05 19:19:20 +03:00
return perf_event_read_local(ee->event, value, enabled, running);
}
BPF_CALL_2(bpf_perf_event_read, struct bpf_map *, map, u64, flags)
{
u64 value = 0;
int err;
err = get_map_perf_counter(map, flags, &value, NULL, NULL);
/*
* this api is ugly since we miss [-22..-2] range of valid
* counter values, but that's uapi
*/
if (err)
return err;
return value;
}
static const struct bpf_func_proto bpf_perf_event_read_proto = {
.func = bpf_perf_event_read,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_CONST_MAP_PTR,
.arg2_type = ARG_ANYTHING,
};
2017-10-05 19:19:20 +03:00
BPF_CALL_4(bpf_perf_event_read_value, struct bpf_map *, map, u64, flags,
struct bpf_perf_event_value *, buf, u32, size)
{
int err = -EINVAL;
if (unlikely(size != sizeof(struct bpf_perf_event_value)))
goto clear;
err = get_map_perf_counter(map, flags, &buf->counter, &buf->enabled,
&buf->running);
if (unlikely(err))
goto clear;
return 0;
clear:
memset(buf, 0, size);
return err;
}
static const struct bpf_func_proto bpf_perf_event_read_value_proto = {
.func = bpf_perf_event_read_value,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_CONST_MAP_PTR,
.arg2_type = ARG_ANYTHING,
.arg3_type = ARG_PTR_TO_UNINIT_MEM,
.arg4_type = ARG_CONST_SIZE,
};
static __always_inline u64
__bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map,
u64 flags, struct perf_sample_data *sd)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
unsigned int cpu = smp_processor_id();
u64 index = flags & BPF_F_INDEX_MASK;
bpf, maps: flush own entries on perf map release The behavior of perf event arrays are quite different from all others as they are tightly coupled to perf event fds, f.e. shown recently by commit e03e7ee34fdd ("perf/bpf: Convert perf_event_array to use struct file") to make refcounting on perf event more robust. A remaining issue that the current code still has is that since additions to the perf event array take a reference on the struct file via perf_event_get() and are only released via fput() (that cleans up the perf event eventually via perf_event_release_kernel()) when the element is either manually removed from the map from user space or automatically when the last reference on the perf event map is dropped. However, this leads us to dangling struct file's when the map gets pinned after the application owning the perf event descriptor exits, and since the struct file reference will in such case only be manually dropped or via pinned file removal, it leads to the perf event living longer than necessary, consuming needlessly resources for that time. Relations between perf event fds and bpf perf event map fds can be rather complex. F.e. maps can act as demuxers among different perf event fds that can possibly be owned by different threads and based on the index selection from the program, events get dispatched to one of the per-cpu fd endpoints. One perf event fd (or, rather a per-cpu set of them) can also live in multiple perf event maps at the same time, listening for events. Also, another requirement is that perf event fds can get closed from application side after they have been attached to the perf event map, so that on exit perf event map will take care of dropping their references eventually. Likewise, when such maps are pinned, the intended behavior is that a user application does bpf_obj_get(), puts its fds in there and on exit when fd is released, they are dropped from the map again, so the map acts rather as connector endpoint. This also makes perf event maps inherently different from program arrays as described in more detail in commit c9da161c6517 ("bpf: fix clearing on persistent program array maps"). To tackle this, map entries are marked by the map struct file that added the element to the map. And when the last reference to that map struct file is released from user space, then the tracked entries are purged from the map. This is okay, because new map struct files instances resp. frontends to the anon inode are provided via bpf_map_new_fd() that is called when we invoke bpf_obj_get_user() for retrieving a pinned map, but also when an initial instance is created via map_create(). The rest is resolved by the vfs layer automatically for us by keeping reference count on the map's struct file. Any concurrent updates on the map slot are fine as well, it just means that perf_event_fd_array_release() needs to delete less of its own entires. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-15 23:47:14 +03:00
struct bpf_event_entry *ee;
struct perf_event *event;
if (index == BPF_F_CURRENT_CPU)
index = cpu;
if (unlikely(index >= array->map.max_entries))
return -E2BIG;
bpf, maps: flush own entries on perf map release The behavior of perf event arrays are quite different from all others as they are tightly coupled to perf event fds, f.e. shown recently by commit e03e7ee34fdd ("perf/bpf: Convert perf_event_array to use struct file") to make refcounting on perf event more robust. A remaining issue that the current code still has is that since additions to the perf event array take a reference on the struct file via perf_event_get() and are only released via fput() (that cleans up the perf event eventually via perf_event_release_kernel()) when the element is either manually removed from the map from user space or automatically when the last reference on the perf event map is dropped. However, this leads us to dangling struct file's when the map gets pinned after the application owning the perf event descriptor exits, and since the struct file reference will in such case only be manually dropped or via pinned file removal, it leads to the perf event living longer than necessary, consuming needlessly resources for that time. Relations between perf event fds and bpf perf event map fds can be rather complex. F.e. maps can act as demuxers among different perf event fds that can possibly be owned by different threads and based on the index selection from the program, events get dispatched to one of the per-cpu fd endpoints. One perf event fd (or, rather a per-cpu set of them) can also live in multiple perf event maps at the same time, listening for events. Also, another requirement is that perf event fds can get closed from application side after they have been attached to the perf event map, so that on exit perf event map will take care of dropping their references eventually. Likewise, when such maps are pinned, the intended behavior is that a user application does bpf_obj_get(), puts its fds in there and on exit when fd is released, they are dropped from the map again, so the map acts rather as connector endpoint. This also makes perf event maps inherently different from program arrays as described in more detail in commit c9da161c6517 ("bpf: fix clearing on persistent program array maps"). To tackle this, map entries are marked by the map struct file that added the element to the map. And when the last reference to that map struct file is released from user space, then the tracked entries are purged from the map. This is okay, because new map struct files instances resp. frontends to the anon inode are provided via bpf_map_new_fd() that is called when we invoke bpf_obj_get_user() for retrieving a pinned map, but also when an initial instance is created via map_create(). The rest is resolved by the vfs layer automatically for us by keeping reference count on the map's struct file. Any concurrent updates on the map slot are fine as well, it just means that perf_event_fd_array_release() needs to delete less of its own entires. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-15 23:47:14 +03:00
ee = READ_ONCE(array->ptrs[index]);
if (!ee)
return -ENOENT;
bpf, maps: flush own entries on perf map release The behavior of perf event arrays are quite different from all others as they are tightly coupled to perf event fds, f.e. shown recently by commit e03e7ee34fdd ("perf/bpf: Convert perf_event_array to use struct file") to make refcounting on perf event more robust. A remaining issue that the current code still has is that since additions to the perf event array take a reference on the struct file via perf_event_get() and are only released via fput() (that cleans up the perf event eventually via perf_event_release_kernel()) when the element is either manually removed from the map from user space or automatically when the last reference on the perf event map is dropped. However, this leads us to dangling struct file's when the map gets pinned after the application owning the perf event descriptor exits, and since the struct file reference will in such case only be manually dropped or via pinned file removal, it leads to the perf event living longer than necessary, consuming needlessly resources for that time. Relations between perf event fds and bpf perf event map fds can be rather complex. F.e. maps can act as demuxers among different perf event fds that can possibly be owned by different threads and based on the index selection from the program, events get dispatched to one of the per-cpu fd endpoints. One perf event fd (or, rather a per-cpu set of them) can also live in multiple perf event maps at the same time, listening for events. Also, another requirement is that perf event fds can get closed from application side after they have been attached to the perf event map, so that on exit perf event map will take care of dropping their references eventually. Likewise, when such maps are pinned, the intended behavior is that a user application does bpf_obj_get(), puts its fds in there and on exit when fd is released, they are dropped from the map again, so the map acts rather as connector endpoint. This also makes perf event maps inherently different from program arrays as described in more detail in commit c9da161c6517 ("bpf: fix clearing on persistent program array maps"). To tackle this, map entries are marked by the map struct file that added the element to the map. And when the last reference to that map struct file is released from user space, then the tracked entries are purged from the map. This is okay, because new map struct files instances resp. frontends to the anon inode are provided via bpf_map_new_fd() that is called when we invoke bpf_obj_get_user() for retrieving a pinned map, but also when an initial instance is created via map_create(). The rest is resolved by the vfs layer automatically for us by keeping reference count on the map's struct file. Any concurrent updates on the map slot are fine as well, it just means that perf_event_fd_array_release() needs to delete less of its own entires. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-15 23:47:14 +03:00
event = ee->event;
if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE ||
event->attr.config != PERF_COUNT_SW_BPF_OUTPUT))
return -EINVAL;
if (unlikely(event->oncpu != cpu))
return -EOPNOTSUPP;
return perf_event_output(event, sd, regs);
}
/*
* Support executing tracepoints in normal, irq, and nmi context that each call
* bpf_perf_event_output
*/
struct bpf_trace_sample_data {
struct perf_sample_data sds[3];
};
static DEFINE_PER_CPU(struct bpf_trace_sample_data, bpf_trace_sds);
static DEFINE_PER_CPU(int, bpf_trace_nest_level);
bpf: add BPF_CALL_x macros for declaring helpers This work adds BPF_CALL_<n>() macros and converts all the eBPF helper functions to use them, in a similar fashion like we do with SYSCALL_DEFINE<n>() macros that are used today. Motivation for this is to hide all the register handling and all necessary casts from the user, so that it is done automatically in the background when adding a BPF_CALL_<n>() call. This makes current helpers easier to review, eases to write future helpers, avoids getting the casting mess wrong, and allows for extending all helpers at once (f.e. build time checks, etc). It also helps detecting more easily in code reviews that unused registers are not instrumented in the code by accident, breaking compatibility with existing programs. BPF_CALL_<n>() internals are quite similar to SYSCALL_DEFINE<n>() ones with some fundamental differences, for example, for generating the actual helper function that carries all u64 regs, we need to fill unused regs, so that we always end up with 5 u64 regs as an argument. I reviewed several 0-5 generated BPF_CALL_<n>() variants of the .i results and they look all as expected. No sparse issue spotted. We let this also sit for a few days with Fengguang's kbuild test robot, and there were no issues seen. On s390, it barked on the "uses dynamic stack allocation" notice, which is an old one from bpf_perf_event_output{,_tp}() reappearing here due to the conversion to the call wrapper, just telling that the perf raw record/frag sits on stack (gcc with s390's -mwarn-dynamicstack), but that's all. Did various runtime tests and they were fine as well. All eBPF helpers are now converted to use these macros, getting rid of a good chunk of all the raw castings. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-09 03:45:31 +03:00
BPF_CALL_5(bpf_perf_event_output, struct pt_regs *, regs, struct bpf_map *, map,
u64, flags, void *, data, u64, size)
{
struct bpf_trace_sample_data *sds = this_cpu_ptr(&bpf_trace_sds);
int nest_level = this_cpu_inc_return(bpf_trace_nest_level);
struct perf_raw_record raw = {
.frag = {
.size = size,
.data = data,
},
};
struct perf_sample_data *sd;
int err;
if (WARN_ON_ONCE(nest_level > ARRAY_SIZE(sds->sds))) {
err = -EBUSY;
goto out;
}
sd = &sds->sds[nest_level - 1];
if (unlikely(flags & ~(BPF_F_INDEX_MASK))) {
err = -EINVAL;
goto out;
}
perf_sample_data_init(sd, 0, 0);
sd->raw = &raw;
err = __bpf_perf_event_output(regs, map, flags, sd);
out:
this_cpu_dec(bpf_trace_nest_level);
return err;
}
static const struct bpf_func_proto bpf_perf_event_output_proto = {
.func = bpf_perf_event_output,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_CONST_MAP_PTR,
.arg3_type = ARG_ANYTHING,
.arg4_type = ARG_PTR_TO_MEM,
bpf: change bpf_perf_event_output arg5 type to ARG_CONST_SIZE_OR_ZERO Commit 9fd29c08e520 ("bpf: improve verifier ARG_CONST_SIZE_OR_ZERO semantics") relaxed the treatment of ARG_CONST_SIZE_OR_ZERO due to the way the compiler generates optimized BPF code when checking boundaries of an argument from C code. A typical example of this optimized code can be generated using the bpf_perf_event_output helper when operating on variable memory: /* len is a generic scalar */ if (len > 0 && len <= 0x7fff) bpf_perf_event_output(ctx, &perf_map, 0, buf, len); 110: (79) r5 = *(u64 *)(r10 -40) 111: (bf) r1 = r5 112: (07) r1 += -1 113: (25) if r1 > 0x7ffe goto pc+6 114: (bf) r1 = r6 115: (18) r2 = 0xffff94e5f166c200 117: (b7) r3 = 0 118: (bf) r4 = r7 119: (85) call bpf_perf_event_output#25 R5 min value is negative, either use unsigned or 'var &= const' With this code, the verifier loses track of the variable. Replacing arg5 with ARG_CONST_SIZE_OR_ZERO is thus desirable since it avoids this quite common case which leads to usability issues, and the compiler generates code that the verifier can more easily test: if (len <= 0x7fff) bpf_perf_event_output(ctx, &perf_map, 0, buf, len); or bpf_perf_event_output(ctx, &perf_map, 0, buf, len & 0x7fff); No changes to the bpf_perf_event_output helper are necessary since it can handle a case where size is 0, and an empty frame is pushed. Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Gianluca Borello <g.borello@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2017-11-22 21:32:56 +03:00
.arg5_type = ARG_CONST_SIZE_OR_ZERO,
};
bpf: Fix bpf_event_output re-entry issue BPF_PROG_TYPE_SOCK_OPS program can reenter bpf_event_output because it can be called from atomic and non-atomic contexts since we don't have bpf_prog_active to prevent it happen. This patch enables 3 levels of nesting to support normal, irq and nmi context. We can easily reproduce the issue by running netperf crr mode with 100 flows and 10 threads from netperf client side. Here is the whole stack dump: [ 515.228898] WARNING: CPU: 20 PID: 14686 at kernel/trace/bpf_trace.c:549 bpf_event_output+0x1f9/0x220 [ 515.228903] CPU: 20 PID: 14686 Comm: tcp_crr Tainted: G W 4.15.0-smp-fixpanic #44 [ 515.228904] Hardware name: Intel TBG,ICH10/Ikaria_QC_1b, BIOS 1.22.0 06/04/2018 [ 515.228905] RIP: 0010:bpf_event_output+0x1f9/0x220 [ 515.228906] RSP: 0018:ffff9a57ffc03938 EFLAGS: 00010246 [ 515.228907] RAX: 0000000000000012 RBX: 0000000000000001 RCX: 0000000000000000 [ 515.228907] RDX: 0000000000000000 RSI: 0000000000000096 RDI: ffffffff836b0f80 [ 515.228908] RBP: ffff9a57ffc039c8 R08: 0000000000000004 R09: 0000000000000012 [ 515.228908] R10: ffff9a57ffc1de40 R11: 0000000000000000 R12: 0000000000000002 [ 515.228909] R13: ffff9a57e13bae00 R14: 00000000ffffffff R15: ffff9a57ffc1e2c0 [ 515.228910] FS: 00007f5a3e6ec700(0000) GS:ffff9a57ffc00000(0000) knlGS:0000000000000000 [ 515.228910] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 515.228911] CR2: 0000537082664fff CR3: 000000061fed6002 CR4: 00000000000226f0 [ 515.228911] Call Trace: [ 515.228913] <IRQ> [ 515.228919] [<ffffffff82c6c6cb>] bpf_sockopt_event_output+0x3b/0x50 [ 515.228923] [<ffffffff8265daee>] ? bpf_ktime_get_ns+0xe/0x10 [ 515.228927] [<ffffffff8266fda5>] ? __cgroup_bpf_run_filter_sock_ops+0x85/0x100 [ 515.228930] [<ffffffff82cf90a5>] ? tcp_init_transfer+0x125/0x150 [ 515.228933] [<ffffffff82cf9159>] ? tcp_finish_connect+0x89/0x110 [ 515.228936] [<ffffffff82cf98e4>] ? tcp_rcv_state_process+0x704/0x1010 [ 515.228939] [<ffffffff82c6e263>] ? sk_filter_trim_cap+0x53/0x2a0 [ 515.228942] [<ffffffff82d90d1f>] ? tcp_v6_inbound_md5_hash+0x6f/0x1d0 [ 515.228945] [<ffffffff82d92160>] ? tcp_v6_do_rcv+0x1c0/0x460 [ 515.228947] [<ffffffff82d93558>] ? tcp_v6_rcv+0x9f8/0xb30 [ 515.228951] [<ffffffff82d737c0>] ? ip6_route_input+0x190/0x220 [ 515.228955] [<ffffffff82d5f7ad>] ? ip6_protocol_deliver_rcu+0x6d/0x450 [ 515.228958] [<ffffffff82d60246>] ? ip6_rcv_finish+0xb6/0x170 [ 515.228961] [<ffffffff82d5fb90>] ? ip6_protocol_deliver_rcu+0x450/0x450 [ 515.228963] [<ffffffff82d60361>] ? ipv6_rcv+0x61/0xe0 [ 515.228966] [<ffffffff82d60190>] ? ipv6_list_rcv+0x330/0x330 [ 515.228969] [<ffffffff82c4976b>] ? __netif_receive_skb_one_core+0x5b/0xa0 [ 515.228972] [<ffffffff82c497d1>] ? __netif_receive_skb+0x21/0x70 [ 515.228975] [<ffffffff82c4a8d2>] ? process_backlog+0xb2/0x150 [ 515.228978] [<ffffffff82c4aadf>] ? net_rx_action+0x16f/0x410 [ 515.228982] [<ffffffff830000dd>] ? __do_softirq+0xdd/0x305 [ 515.228986] [<ffffffff8252cfdc>] ? irq_exit+0x9c/0xb0 [ 515.228989] [<ffffffff82e02de5>] ? smp_call_function_single_interrupt+0x65/0x120 [ 515.228991] [<ffffffff82e020e1>] ? call_function_single_interrupt+0x81/0x90 [ 515.228992] </IRQ> [ 515.228996] [<ffffffff82a11ff0>] ? io_serial_in+0x20/0x20 [ 515.229000] [<ffffffff8259c040>] ? console_unlock+0x230/0x490 [ 515.229003] [<ffffffff8259cbaa>] ? vprintk_emit+0x26a/0x2a0 [ 515.229006] [<ffffffff8259cbff>] ? vprintk_default+0x1f/0x30 [ 515.229008] [<ffffffff8259d9f5>] ? vprintk_func+0x35/0x70 [ 515.229011] [<ffffffff8259d4bb>] ? printk+0x50/0x66 [ 515.229013] [<ffffffff82637637>] ? bpf_event_output+0xb7/0x220 [ 515.229016] [<ffffffff82c6c6cb>] ? bpf_sockopt_event_output+0x3b/0x50 [ 515.229019] [<ffffffff8265daee>] ? bpf_ktime_get_ns+0xe/0x10 [ 515.229023] [<ffffffff82c29e87>] ? release_sock+0x97/0xb0 [ 515.229026] [<ffffffff82ce9d6a>] ? tcp_recvmsg+0x31a/0xda0 [ 515.229029] [<ffffffff8266fda5>] ? __cgroup_bpf_run_filter_sock_ops+0x85/0x100 [ 515.229032] [<ffffffff82ce77c1>] ? tcp_set_state+0x191/0x1b0 [ 515.229035] [<ffffffff82ced10e>] ? tcp_disconnect+0x2e/0x600 [ 515.229038] [<ffffffff82cecbbb>] ? tcp_close+0x3eb/0x460 [ 515.229040] [<ffffffff82d21082>] ? inet_release+0x42/0x70 [ 515.229043] [<ffffffff82d58809>] ? inet6_release+0x39/0x50 [ 515.229046] [<ffffffff82c1f32d>] ? __sock_release+0x4d/0xd0 [ 515.229049] [<ffffffff82c1f3e5>] ? sock_close+0x15/0x20 [ 515.229052] [<ffffffff8273b517>] ? __fput+0xe7/0x1f0 [ 515.229055] [<ffffffff8273b66e>] ? ____fput+0xe/0x10 [ 515.229058] [<ffffffff82547bf2>] ? task_work_run+0x82/0xb0 [ 515.229061] [<ffffffff824086df>] ? exit_to_usermode_loop+0x7e/0x11f [ 515.229064] [<ffffffff82408171>] ? do_syscall_64+0x111/0x130 [ 515.229067] [<ffffffff82e0007c>] ? entry_SYSCALL_64_after_hwframe+0x3d/0xa2 Fixes: a5a3a828cd00 ("bpf: add perf event notificaton support for sock_ops") Signed-off-by: Allan Zhang <allanzhang@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Stanislav Fomichev <sdf@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20190925234312.94063-2-allanzhang@google.com
2019-09-26 02:43:12 +03:00
static DEFINE_PER_CPU(int, bpf_event_output_nest_level);
struct bpf_nested_pt_regs {
struct pt_regs regs[3];
};
static DEFINE_PER_CPU(struct bpf_nested_pt_regs, bpf_pt_regs);
static DEFINE_PER_CPU(struct bpf_trace_sample_data, bpf_misc_sds);
bpf: add event output helper for notifications/sampling/logging This patch adds a new helper for cls/act programs that can push events to user space applications. For networking, this can be f.e. for sampling, debugging, logging purposes or pushing of arbitrary wake-up events. The idea is similar to a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") and 39111695b1b8 ("samples: bpf: add bpf_perf_event_output example"). The eBPF program utilizes a perf event array map that user space populates with fds from perf_event_open(), the eBPF program calls into the helper f.e. as skb_event_output(skb, &my_map, BPF_F_CURRENT_CPU, raw, sizeof(raw)) so that the raw data is pushed into the fd f.e. at the map index of the current CPU. User space can poll/mmap/etc on this and has a data channel for receiving events that can be post-processed. The nice thing is that since the eBPF program and user space application making use of it are tightly coupled, they can define their own arbitrary raw data format and what/when they want to push. While f.e. packet headers could be one part of the meta data that is being pushed, this is not a substitute for things like packet sockets as whole packet is not being pushed and push is only done in a single direction. Intention is more of a generically usable, efficient event pipe to applications. Workflow is that tc can pin the map and applications can attach themselves e.g. after cls/act setup to one or multiple map slots, demuxing is done by the eBPF program. Adding this facility is with minimal effort, it reuses the helper introduced in a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") and we get its functionality for free by overloading its BPF_FUNC_ identifier for cls/act programs, ctx is currently unused, but will be made use of in future. Example will be added to iproute2's BPF example files. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-18 22:01:24 +03:00
bpf: avoid stack copy and use skb ctx for event output This work addresses a couple of issues bpf_skb_event_output() helper currently has: i) We need two copies instead of just a single one for the skb data when it should be part of a sample. The data can be non-linear and thus needs to be extracted via bpf_skb_load_bytes() helper first, and then copied once again into the ring buffer slot. ii) Since bpf_skb_load_bytes() currently needs to be used first, the helper needs to see a constant size on the passed stack buffer to make sure BPF verifier can do sanity checks on it during verification time. Thus, just passing skb->len (or any other non-constant value) wouldn't work, but changing bpf_skb_load_bytes() is also not the proper solution, since the two copies are generally still needed. iii) bpf_skb_load_bytes() is just for rather small buffers like headers, since they need to sit on the limited BPF stack anyway. Instead of working around in bpf_skb_load_bytes(), this work improves the bpf_skb_event_output() helper to address all 3 at once. We can make use of the passed in skb context that we have in the helper anyway, and use some of the reserved flag bits as a length argument. The helper will use the new __output_custom() facility from perf side with bpf_skb_copy() as callback helper to walk and extract the data. It will pass the data for setup to bpf_event_output(), which generates and pushes the raw record with an additional frag part. The linear data used in the first frag of the record serves as programmatically defined meta data passed along with the appended sample. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-07-14 19:08:05 +03:00
u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy)
bpf: add event output helper for notifications/sampling/logging This patch adds a new helper for cls/act programs that can push events to user space applications. For networking, this can be f.e. for sampling, debugging, logging purposes or pushing of arbitrary wake-up events. The idea is similar to a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") and 39111695b1b8 ("samples: bpf: add bpf_perf_event_output example"). The eBPF program utilizes a perf event array map that user space populates with fds from perf_event_open(), the eBPF program calls into the helper f.e. as skb_event_output(skb, &my_map, BPF_F_CURRENT_CPU, raw, sizeof(raw)) so that the raw data is pushed into the fd f.e. at the map index of the current CPU. User space can poll/mmap/etc on this and has a data channel for receiving events that can be post-processed. The nice thing is that since the eBPF program and user space application making use of it are tightly coupled, they can define their own arbitrary raw data format and what/when they want to push. While f.e. packet headers could be one part of the meta data that is being pushed, this is not a substitute for things like packet sockets as whole packet is not being pushed and push is only done in a single direction. Intention is more of a generically usable, efficient event pipe to applications. Workflow is that tc can pin the map and applications can attach themselves e.g. after cls/act setup to one or multiple map slots, demuxing is done by the eBPF program. Adding this facility is with minimal effort, it reuses the helper introduced in a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") and we get its functionality for free by overloading its BPF_FUNC_ identifier for cls/act programs, ctx is currently unused, but will be made use of in future. Example will be added to iproute2's BPF example files. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-18 22:01:24 +03:00
{
bpf: Fix bpf_event_output re-entry issue BPF_PROG_TYPE_SOCK_OPS program can reenter bpf_event_output because it can be called from atomic and non-atomic contexts since we don't have bpf_prog_active to prevent it happen. This patch enables 3 levels of nesting to support normal, irq and nmi context. We can easily reproduce the issue by running netperf crr mode with 100 flows and 10 threads from netperf client side. Here is the whole stack dump: [ 515.228898] WARNING: CPU: 20 PID: 14686 at kernel/trace/bpf_trace.c:549 bpf_event_output+0x1f9/0x220 [ 515.228903] CPU: 20 PID: 14686 Comm: tcp_crr Tainted: G W 4.15.0-smp-fixpanic #44 [ 515.228904] Hardware name: Intel TBG,ICH10/Ikaria_QC_1b, BIOS 1.22.0 06/04/2018 [ 515.228905] RIP: 0010:bpf_event_output+0x1f9/0x220 [ 515.228906] RSP: 0018:ffff9a57ffc03938 EFLAGS: 00010246 [ 515.228907] RAX: 0000000000000012 RBX: 0000000000000001 RCX: 0000000000000000 [ 515.228907] RDX: 0000000000000000 RSI: 0000000000000096 RDI: ffffffff836b0f80 [ 515.228908] RBP: ffff9a57ffc039c8 R08: 0000000000000004 R09: 0000000000000012 [ 515.228908] R10: ffff9a57ffc1de40 R11: 0000000000000000 R12: 0000000000000002 [ 515.228909] R13: ffff9a57e13bae00 R14: 00000000ffffffff R15: ffff9a57ffc1e2c0 [ 515.228910] FS: 00007f5a3e6ec700(0000) GS:ffff9a57ffc00000(0000) knlGS:0000000000000000 [ 515.228910] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 515.228911] CR2: 0000537082664fff CR3: 000000061fed6002 CR4: 00000000000226f0 [ 515.228911] Call Trace: [ 515.228913] <IRQ> [ 515.228919] [<ffffffff82c6c6cb>] bpf_sockopt_event_output+0x3b/0x50 [ 515.228923] [<ffffffff8265daee>] ? bpf_ktime_get_ns+0xe/0x10 [ 515.228927] [<ffffffff8266fda5>] ? __cgroup_bpf_run_filter_sock_ops+0x85/0x100 [ 515.228930] [<ffffffff82cf90a5>] ? tcp_init_transfer+0x125/0x150 [ 515.228933] [<ffffffff82cf9159>] ? tcp_finish_connect+0x89/0x110 [ 515.228936] [<ffffffff82cf98e4>] ? tcp_rcv_state_process+0x704/0x1010 [ 515.228939] [<ffffffff82c6e263>] ? sk_filter_trim_cap+0x53/0x2a0 [ 515.228942] [<ffffffff82d90d1f>] ? tcp_v6_inbound_md5_hash+0x6f/0x1d0 [ 515.228945] [<ffffffff82d92160>] ? tcp_v6_do_rcv+0x1c0/0x460 [ 515.228947] [<ffffffff82d93558>] ? tcp_v6_rcv+0x9f8/0xb30 [ 515.228951] [<ffffffff82d737c0>] ? ip6_route_input+0x190/0x220 [ 515.228955] [<ffffffff82d5f7ad>] ? ip6_protocol_deliver_rcu+0x6d/0x450 [ 515.228958] [<ffffffff82d60246>] ? ip6_rcv_finish+0xb6/0x170 [ 515.228961] [<ffffffff82d5fb90>] ? ip6_protocol_deliver_rcu+0x450/0x450 [ 515.228963] [<ffffffff82d60361>] ? ipv6_rcv+0x61/0xe0 [ 515.228966] [<ffffffff82d60190>] ? ipv6_list_rcv+0x330/0x330 [ 515.228969] [<ffffffff82c4976b>] ? __netif_receive_skb_one_core+0x5b/0xa0 [ 515.228972] [<ffffffff82c497d1>] ? __netif_receive_skb+0x21/0x70 [ 515.228975] [<ffffffff82c4a8d2>] ? process_backlog+0xb2/0x150 [ 515.228978] [<ffffffff82c4aadf>] ? net_rx_action+0x16f/0x410 [ 515.228982] [<ffffffff830000dd>] ? __do_softirq+0xdd/0x305 [ 515.228986] [<ffffffff8252cfdc>] ? irq_exit+0x9c/0xb0 [ 515.228989] [<ffffffff82e02de5>] ? smp_call_function_single_interrupt+0x65/0x120 [ 515.228991] [<ffffffff82e020e1>] ? call_function_single_interrupt+0x81/0x90 [ 515.228992] </IRQ> [ 515.228996] [<ffffffff82a11ff0>] ? io_serial_in+0x20/0x20 [ 515.229000] [<ffffffff8259c040>] ? console_unlock+0x230/0x490 [ 515.229003] [<ffffffff8259cbaa>] ? vprintk_emit+0x26a/0x2a0 [ 515.229006] [<ffffffff8259cbff>] ? vprintk_default+0x1f/0x30 [ 515.229008] [<ffffffff8259d9f5>] ? vprintk_func+0x35/0x70 [ 515.229011] [<ffffffff8259d4bb>] ? printk+0x50/0x66 [ 515.229013] [<ffffffff82637637>] ? bpf_event_output+0xb7/0x220 [ 515.229016] [<ffffffff82c6c6cb>] ? bpf_sockopt_event_output+0x3b/0x50 [ 515.229019] [<ffffffff8265daee>] ? bpf_ktime_get_ns+0xe/0x10 [ 515.229023] [<ffffffff82c29e87>] ? release_sock+0x97/0xb0 [ 515.229026] [<ffffffff82ce9d6a>] ? tcp_recvmsg+0x31a/0xda0 [ 515.229029] [<ffffffff8266fda5>] ? __cgroup_bpf_run_filter_sock_ops+0x85/0x100 [ 515.229032] [<ffffffff82ce77c1>] ? tcp_set_state+0x191/0x1b0 [ 515.229035] [<ffffffff82ced10e>] ? tcp_disconnect+0x2e/0x600 [ 515.229038] [<ffffffff82cecbbb>] ? tcp_close+0x3eb/0x460 [ 515.229040] [<ffffffff82d21082>] ? inet_release+0x42/0x70 [ 515.229043] [<ffffffff82d58809>] ? inet6_release+0x39/0x50 [ 515.229046] [<ffffffff82c1f32d>] ? __sock_release+0x4d/0xd0 [ 515.229049] [<ffffffff82c1f3e5>] ? sock_close+0x15/0x20 [ 515.229052] [<ffffffff8273b517>] ? __fput+0xe7/0x1f0 [ 515.229055] [<ffffffff8273b66e>] ? ____fput+0xe/0x10 [ 515.229058] [<ffffffff82547bf2>] ? task_work_run+0x82/0xb0 [ 515.229061] [<ffffffff824086df>] ? exit_to_usermode_loop+0x7e/0x11f [ 515.229064] [<ffffffff82408171>] ? do_syscall_64+0x111/0x130 [ 515.229067] [<ffffffff82e0007c>] ? entry_SYSCALL_64_after_hwframe+0x3d/0xa2 Fixes: a5a3a828cd00 ("bpf: add perf event notificaton support for sock_ops") Signed-off-by: Allan Zhang <allanzhang@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Stanislav Fomichev <sdf@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20190925234312.94063-2-allanzhang@google.com
2019-09-26 02:43:12 +03:00
int nest_level = this_cpu_inc_return(bpf_event_output_nest_level);
bpf: avoid stack copy and use skb ctx for event output This work addresses a couple of issues bpf_skb_event_output() helper currently has: i) We need two copies instead of just a single one for the skb data when it should be part of a sample. The data can be non-linear and thus needs to be extracted via bpf_skb_load_bytes() helper first, and then copied once again into the ring buffer slot. ii) Since bpf_skb_load_bytes() currently needs to be used first, the helper needs to see a constant size on the passed stack buffer to make sure BPF verifier can do sanity checks on it during verification time. Thus, just passing skb->len (or any other non-constant value) wouldn't work, but changing bpf_skb_load_bytes() is also not the proper solution, since the two copies are generally still needed. iii) bpf_skb_load_bytes() is just for rather small buffers like headers, since they need to sit on the limited BPF stack anyway. Instead of working around in bpf_skb_load_bytes(), this work improves the bpf_skb_event_output() helper to address all 3 at once. We can make use of the passed in skb context that we have in the helper anyway, and use some of the reserved flag bits as a length argument. The helper will use the new __output_custom() facility from perf side with bpf_skb_copy() as callback helper to walk and extract the data. It will pass the data for setup to bpf_event_output(), which generates and pushes the raw record with an additional frag part. The linear data used in the first frag of the record serves as programmatically defined meta data passed along with the appended sample. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-07-14 19:08:05 +03:00
struct perf_raw_frag frag = {
.copy = ctx_copy,
.size = ctx_size,
.data = ctx,
};
struct perf_raw_record raw = {
.frag = {
{
.next = ctx_size ? &frag : NULL,
},
bpf: avoid stack copy and use skb ctx for event output This work addresses a couple of issues bpf_skb_event_output() helper currently has: i) We need two copies instead of just a single one for the skb data when it should be part of a sample. The data can be non-linear and thus needs to be extracted via bpf_skb_load_bytes() helper first, and then copied once again into the ring buffer slot. ii) Since bpf_skb_load_bytes() currently needs to be used first, the helper needs to see a constant size on the passed stack buffer to make sure BPF verifier can do sanity checks on it during verification time. Thus, just passing skb->len (or any other non-constant value) wouldn't work, but changing bpf_skb_load_bytes() is also not the proper solution, since the two copies are generally still needed. iii) bpf_skb_load_bytes() is just for rather small buffers like headers, since they need to sit on the limited BPF stack anyway. Instead of working around in bpf_skb_load_bytes(), this work improves the bpf_skb_event_output() helper to address all 3 at once. We can make use of the passed in skb context that we have in the helper anyway, and use some of the reserved flag bits as a length argument. The helper will use the new __output_custom() facility from perf side with bpf_skb_copy() as callback helper to walk and extract the data. It will pass the data for setup to bpf_event_output(), which generates and pushes the raw record with an additional frag part. The linear data used in the first frag of the record serves as programmatically defined meta data passed along with the appended sample. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-07-14 19:08:05 +03:00
.size = meta_size,
.data = meta,
},
};
bpf: Fix bpf_event_output re-entry issue BPF_PROG_TYPE_SOCK_OPS program can reenter bpf_event_output because it can be called from atomic and non-atomic contexts since we don't have bpf_prog_active to prevent it happen. This patch enables 3 levels of nesting to support normal, irq and nmi context. We can easily reproduce the issue by running netperf crr mode with 100 flows and 10 threads from netperf client side. Here is the whole stack dump: [ 515.228898] WARNING: CPU: 20 PID: 14686 at kernel/trace/bpf_trace.c:549 bpf_event_output+0x1f9/0x220 [ 515.228903] CPU: 20 PID: 14686 Comm: tcp_crr Tainted: G W 4.15.0-smp-fixpanic #44 [ 515.228904] Hardware name: Intel TBG,ICH10/Ikaria_QC_1b, BIOS 1.22.0 06/04/2018 [ 515.228905] RIP: 0010:bpf_event_output+0x1f9/0x220 [ 515.228906] RSP: 0018:ffff9a57ffc03938 EFLAGS: 00010246 [ 515.228907] RAX: 0000000000000012 RBX: 0000000000000001 RCX: 0000000000000000 [ 515.228907] RDX: 0000000000000000 RSI: 0000000000000096 RDI: ffffffff836b0f80 [ 515.228908] RBP: ffff9a57ffc039c8 R08: 0000000000000004 R09: 0000000000000012 [ 515.228908] R10: ffff9a57ffc1de40 R11: 0000000000000000 R12: 0000000000000002 [ 515.228909] R13: ffff9a57e13bae00 R14: 00000000ffffffff R15: ffff9a57ffc1e2c0 [ 515.228910] FS: 00007f5a3e6ec700(0000) GS:ffff9a57ffc00000(0000) knlGS:0000000000000000 [ 515.228910] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 515.228911] CR2: 0000537082664fff CR3: 000000061fed6002 CR4: 00000000000226f0 [ 515.228911] Call Trace: [ 515.228913] <IRQ> [ 515.228919] [<ffffffff82c6c6cb>] bpf_sockopt_event_output+0x3b/0x50 [ 515.228923] [<ffffffff8265daee>] ? bpf_ktime_get_ns+0xe/0x10 [ 515.228927] [<ffffffff8266fda5>] ? __cgroup_bpf_run_filter_sock_ops+0x85/0x100 [ 515.228930] [<ffffffff82cf90a5>] ? tcp_init_transfer+0x125/0x150 [ 515.228933] [<ffffffff82cf9159>] ? tcp_finish_connect+0x89/0x110 [ 515.228936] [<ffffffff82cf98e4>] ? tcp_rcv_state_process+0x704/0x1010 [ 515.228939] [<ffffffff82c6e263>] ? sk_filter_trim_cap+0x53/0x2a0 [ 515.228942] [<ffffffff82d90d1f>] ? tcp_v6_inbound_md5_hash+0x6f/0x1d0 [ 515.228945] [<ffffffff82d92160>] ? tcp_v6_do_rcv+0x1c0/0x460 [ 515.228947] [<ffffffff82d93558>] ? tcp_v6_rcv+0x9f8/0xb30 [ 515.228951] [<ffffffff82d737c0>] ? ip6_route_input+0x190/0x220 [ 515.228955] [<ffffffff82d5f7ad>] ? ip6_protocol_deliver_rcu+0x6d/0x450 [ 515.228958] [<ffffffff82d60246>] ? ip6_rcv_finish+0xb6/0x170 [ 515.228961] [<ffffffff82d5fb90>] ? ip6_protocol_deliver_rcu+0x450/0x450 [ 515.228963] [<ffffffff82d60361>] ? ipv6_rcv+0x61/0xe0 [ 515.228966] [<ffffffff82d60190>] ? ipv6_list_rcv+0x330/0x330 [ 515.228969] [<ffffffff82c4976b>] ? __netif_receive_skb_one_core+0x5b/0xa0 [ 515.228972] [<ffffffff82c497d1>] ? __netif_receive_skb+0x21/0x70 [ 515.228975] [<ffffffff82c4a8d2>] ? process_backlog+0xb2/0x150 [ 515.228978] [<ffffffff82c4aadf>] ? net_rx_action+0x16f/0x410 [ 515.228982] [<ffffffff830000dd>] ? __do_softirq+0xdd/0x305 [ 515.228986] [<ffffffff8252cfdc>] ? irq_exit+0x9c/0xb0 [ 515.228989] [<ffffffff82e02de5>] ? smp_call_function_single_interrupt+0x65/0x120 [ 515.228991] [<ffffffff82e020e1>] ? call_function_single_interrupt+0x81/0x90 [ 515.228992] </IRQ> [ 515.228996] [<ffffffff82a11ff0>] ? io_serial_in+0x20/0x20 [ 515.229000] [<ffffffff8259c040>] ? console_unlock+0x230/0x490 [ 515.229003] [<ffffffff8259cbaa>] ? vprintk_emit+0x26a/0x2a0 [ 515.229006] [<ffffffff8259cbff>] ? vprintk_default+0x1f/0x30 [ 515.229008] [<ffffffff8259d9f5>] ? vprintk_func+0x35/0x70 [ 515.229011] [<ffffffff8259d4bb>] ? printk+0x50/0x66 [ 515.229013] [<ffffffff82637637>] ? bpf_event_output+0xb7/0x220 [ 515.229016] [<ffffffff82c6c6cb>] ? bpf_sockopt_event_output+0x3b/0x50 [ 515.229019] [<ffffffff8265daee>] ? bpf_ktime_get_ns+0xe/0x10 [ 515.229023] [<ffffffff82c29e87>] ? release_sock+0x97/0xb0 [ 515.229026] [<ffffffff82ce9d6a>] ? tcp_recvmsg+0x31a/0xda0 [ 515.229029] [<ffffffff8266fda5>] ? __cgroup_bpf_run_filter_sock_ops+0x85/0x100 [ 515.229032] [<ffffffff82ce77c1>] ? tcp_set_state+0x191/0x1b0 [ 515.229035] [<ffffffff82ced10e>] ? tcp_disconnect+0x2e/0x600 [ 515.229038] [<ffffffff82cecbbb>] ? tcp_close+0x3eb/0x460 [ 515.229040] [<ffffffff82d21082>] ? inet_release+0x42/0x70 [ 515.229043] [<ffffffff82d58809>] ? inet6_release+0x39/0x50 [ 515.229046] [<ffffffff82c1f32d>] ? __sock_release+0x4d/0xd0 [ 515.229049] [<ffffffff82c1f3e5>] ? sock_close+0x15/0x20 [ 515.229052] [<ffffffff8273b517>] ? __fput+0xe7/0x1f0 [ 515.229055] [<ffffffff8273b66e>] ? ____fput+0xe/0x10 [ 515.229058] [<ffffffff82547bf2>] ? task_work_run+0x82/0xb0 [ 515.229061] [<ffffffff824086df>] ? exit_to_usermode_loop+0x7e/0x11f [ 515.229064] [<ffffffff82408171>] ? do_syscall_64+0x111/0x130 [ 515.229067] [<ffffffff82e0007c>] ? entry_SYSCALL_64_after_hwframe+0x3d/0xa2 Fixes: a5a3a828cd00 ("bpf: add perf event notificaton support for sock_ops") Signed-off-by: Allan Zhang <allanzhang@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Stanislav Fomichev <sdf@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20190925234312.94063-2-allanzhang@google.com
2019-09-26 02:43:12 +03:00
struct perf_sample_data *sd;
struct pt_regs *regs;
u64 ret;
if (WARN_ON_ONCE(nest_level > ARRAY_SIZE(bpf_misc_sds.sds))) {
ret = -EBUSY;
goto out;
}
sd = this_cpu_ptr(&bpf_misc_sds.sds[nest_level - 1]);
regs = this_cpu_ptr(&bpf_pt_regs.regs[nest_level - 1]);
bpf: add event output helper for notifications/sampling/logging This patch adds a new helper for cls/act programs that can push events to user space applications. For networking, this can be f.e. for sampling, debugging, logging purposes or pushing of arbitrary wake-up events. The idea is similar to a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") and 39111695b1b8 ("samples: bpf: add bpf_perf_event_output example"). The eBPF program utilizes a perf event array map that user space populates with fds from perf_event_open(), the eBPF program calls into the helper f.e. as skb_event_output(skb, &my_map, BPF_F_CURRENT_CPU, raw, sizeof(raw)) so that the raw data is pushed into the fd f.e. at the map index of the current CPU. User space can poll/mmap/etc on this and has a data channel for receiving events that can be post-processed. The nice thing is that since the eBPF program and user space application making use of it are tightly coupled, they can define their own arbitrary raw data format and what/when they want to push. While f.e. packet headers could be one part of the meta data that is being pushed, this is not a substitute for things like packet sockets as whole packet is not being pushed and push is only done in a single direction. Intention is more of a generically usable, efficient event pipe to applications. Workflow is that tc can pin the map and applications can attach themselves e.g. after cls/act setup to one or multiple map slots, demuxing is done by the eBPF program. Adding this facility is with minimal effort, it reuses the helper introduced in a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") and we get its functionality for free by overloading its BPF_FUNC_ identifier for cls/act programs, ctx is currently unused, but will be made use of in future. Example will be added to iproute2's BPF example files. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-18 22:01:24 +03:00
perf_fetch_caller_regs(regs);
perf_sample_data_init(sd, 0, 0);
sd->raw = &raw;
bpf: add event output helper for notifications/sampling/logging This patch adds a new helper for cls/act programs that can push events to user space applications. For networking, this can be f.e. for sampling, debugging, logging purposes or pushing of arbitrary wake-up events. The idea is similar to a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") and 39111695b1b8 ("samples: bpf: add bpf_perf_event_output example"). The eBPF program utilizes a perf event array map that user space populates with fds from perf_event_open(), the eBPF program calls into the helper f.e. as skb_event_output(skb, &my_map, BPF_F_CURRENT_CPU, raw, sizeof(raw)) so that the raw data is pushed into the fd f.e. at the map index of the current CPU. User space can poll/mmap/etc on this and has a data channel for receiving events that can be post-processed. The nice thing is that since the eBPF program and user space application making use of it are tightly coupled, they can define their own arbitrary raw data format and what/when they want to push. While f.e. packet headers could be one part of the meta data that is being pushed, this is not a substitute for things like packet sockets as whole packet is not being pushed and push is only done in a single direction. Intention is more of a generically usable, efficient event pipe to applications. Workflow is that tc can pin the map and applications can attach themselves e.g. after cls/act setup to one or multiple map slots, demuxing is done by the eBPF program. Adding this facility is with minimal effort, it reuses the helper introduced in a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") and we get its functionality for free by overloading its BPF_FUNC_ identifier for cls/act programs, ctx is currently unused, but will be made use of in future. Example will be added to iproute2's BPF example files. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-18 22:01:24 +03:00
bpf: Fix bpf_event_output re-entry issue BPF_PROG_TYPE_SOCK_OPS program can reenter bpf_event_output because it can be called from atomic and non-atomic contexts since we don't have bpf_prog_active to prevent it happen. This patch enables 3 levels of nesting to support normal, irq and nmi context. We can easily reproduce the issue by running netperf crr mode with 100 flows and 10 threads from netperf client side. Here is the whole stack dump: [ 515.228898] WARNING: CPU: 20 PID: 14686 at kernel/trace/bpf_trace.c:549 bpf_event_output+0x1f9/0x220 [ 515.228903] CPU: 20 PID: 14686 Comm: tcp_crr Tainted: G W 4.15.0-smp-fixpanic #44 [ 515.228904] Hardware name: Intel TBG,ICH10/Ikaria_QC_1b, BIOS 1.22.0 06/04/2018 [ 515.228905] RIP: 0010:bpf_event_output+0x1f9/0x220 [ 515.228906] RSP: 0018:ffff9a57ffc03938 EFLAGS: 00010246 [ 515.228907] RAX: 0000000000000012 RBX: 0000000000000001 RCX: 0000000000000000 [ 515.228907] RDX: 0000000000000000 RSI: 0000000000000096 RDI: ffffffff836b0f80 [ 515.228908] RBP: ffff9a57ffc039c8 R08: 0000000000000004 R09: 0000000000000012 [ 515.228908] R10: ffff9a57ffc1de40 R11: 0000000000000000 R12: 0000000000000002 [ 515.228909] R13: ffff9a57e13bae00 R14: 00000000ffffffff R15: ffff9a57ffc1e2c0 [ 515.228910] FS: 00007f5a3e6ec700(0000) GS:ffff9a57ffc00000(0000) knlGS:0000000000000000 [ 515.228910] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 515.228911] CR2: 0000537082664fff CR3: 000000061fed6002 CR4: 00000000000226f0 [ 515.228911] Call Trace: [ 515.228913] <IRQ> [ 515.228919] [<ffffffff82c6c6cb>] bpf_sockopt_event_output+0x3b/0x50 [ 515.228923] [<ffffffff8265daee>] ? bpf_ktime_get_ns+0xe/0x10 [ 515.228927] [<ffffffff8266fda5>] ? __cgroup_bpf_run_filter_sock_ops+0x85/0x100 [ 515.228930] [<ffffffff82cf90a5>] ? tcp_init_transfer+0x125/0x150 [ 515.228933] [<ffffffff82cf9159>] ? tcp_finish_connect+0x89/0x110 [ 515.228936] [<ffffffff82cf98e4>] ? tcp_rcv_state_process+0x704/0x1010 [ 515.228939] [<ffffffff82c6e263>] ? sk_filter_trim_cap+0x53/0x2a0 [ 515.228942] [<ffffffff82d90d1f>] ? tcp_v6_inbound_md5_hash+0x6f/0x1d0 [ 515.228945] [<ffffffff82d92160>] ? tcp_v6_do_rcv+0x1c0/0x460 [ 515.228947] [<ffffffff82d93558>] ? tcp_v6_rcv+0x9f8/0xb30 [ 515.228951] [<ffffffff82d737c0>] ? ip6_route_input+0x190/0x220 [ 515.228955] [<ffffffff82d5f7ad>] ? ip6_protocol_deliver_rcu+0x6d/0x450 [ 515.228958] [<ffffffff82d60246>] ? ip6_rcv_finish+0xb6/0x170 [ 515.228961] [<ffffffff82d5fb90>] ? ip6_protocol_deliver_rcu+0x450/0x450 [ 515.228963] [<ffffffff82d60361>] ? ipv6_rcv+0x61/0xe0 [ 515.228966] [<ffffffff82d60190>] ? ipv6_list_rcv+0x330/0x330 [ 515.228969] [<ffffffff82c4976b>] ? __netif_receive_skb_one_core+0x5b/0xa0 [ 515.228972] [<ffffffff82c497d1>] ? __netif_receive_skb+0x21/0x70 [ 515.228975] [<ffffffff82c4a8d2>] ? process_backlog+0xb2/0x150 [ 515.228978] [<ffffffff82c4aadf>] ? net_rx_action+0x16f/0x410 [ 515.228982] [<ffffffff830000dd>] ? __do_softirq+0xdd/0x305 [ 515.228986] [<ffffffff8252cfdc>] ? irq_exit+0x9c/0xb0 [ 515.228989] [<ffffffff82e02de5>] ? smp_call_function_single_interrupt+0x65/0x120 [ 515.228991] [<ffffffff82e020e1>] ? call_function_single_interrupt+0x81/0x90 [ 515.228992] </IRQ> [ 515.228996] [<ffffffff82a11ff0>] ? io_serial_in+0x20/0x20 [ 515.229000] [<ffffffff8259c040>] ? console_unlock+0x230/0x490 [ 515.229003] [<ffffffff8259cbaa>] ? vprintk_emit+0x26a/0x2a0 [ 515.229006] [<ffffffff8259cbff>] ? vprintk_default+0x1f/0x30 [ 515.229008] [<ffffffff8259d9f5>] ? vprintk_func+0x35/0x70 [ 515.229011] [<ffffffff8259d4bb>] ? printk+0x50/0x66 [ 515.229013] [<ffffffff82637637>] ? bpf_event_output+0xb7/0x220 [ 515.229016] [<ffffffff82c6c6cb>] ? bpf_sockopt_event_output+0x3b/0x50 [ 515.229019] [<ffffffff8265daee>] ? bpf_ktime_get_ns+0xe/0x10 [ 515.229023] [<ffffffff82c29e87>] ? release_sock+0x97/0xb0 [ 515.229026] [<ffffffff82ce9d6a>] ? tcp_recvmsg+0x31a/0xda0 [ 515.229029] [<ffffffff8266fda5>] ? __cgroup_bpf_run_filter_sock_ops+0x85/0x100 [ 515.229032] [<ffffffff82ce77c1>] ? tcp_set_state+0x191/0x1b0 [ 515.229035] [<ffffffff82ced10e>] ? tcp_disconnect+0x2e/0x600 [ 515.229038] [<ffffffff82cecbbb>] ? tcp_close+0x3eb/0x460 [ 515.229040] [<ffffffff82d21082>] ? inet_release+0x42/0x70 [ 515.229043] [<ffffffff82d58809>] ? inet6_release+0x39/0x50 [ 515.229046] [<ffffffff82c1f32d>] ? __sock_release+0x4d/0xd0 [ 515.229049] [<ffffffff82c1f3e5>] ? sock_close+0x15/0x20 [ 515.229052] [<ffffffff8273b517>] ? __fput+0xe7/0x1f0 [ 515.229055] [<ffffffff8273b66e>] ? ____fput+0xe/0x10 [ 515.229058] [<ffffffff82547bf2>] ? task_work_run+0x82/0xb0 [ 515.229061] [<ffffffff824086df>] ? exit_to_usermode_loop+0x7e/0x11f [ 515.229064] [<ffffffff82408171>] ? do_syscall_64+0x111/0x130 [ 515.229067] [<ffffffff82e0007c>] ? entry_SYSCALL_64_after_hwframe+0x3d/0xa2 Fixes: a5a3a828cd00 ("bpf: add perf event notificaton support for sock_ops") Signed-off-by: Allan Zhang <allanzhang@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Stanislav Fomichev <sdf@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20190925234312.94063-2-allanzhang@google.com
2019-09-26 02:43:12 +03:00
ret = __bpf_perf_event_output(regs, map, flags, sd);
out:
this_cpu_dec(bpf_event_output_nest_level);
return ret;
bpf: add event output helper for notifications/sampling/logging This patch adds a new helper for cls/act programs that can push events to user space applications. For networking, this can be f.e. for sampling, debugging, logging purposes or pushing of arbitrary wake-up events. The idea is similar to a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") and 39111695b1b8 ("samples: bpf: add bpf_perf_event_output example"). The eBPF program utilizes a perf event array map that user space populates with fds from perf_event_open(), the eBPF program calls into the helper f.e. as skb_event_output(skb, &my_map, BPF_F_CURRENT_CPU, raw, sizeof(raw)) so that the raw data is pushed into the fd f.e. at the map index of the current CPU. User space can poll/mmap/etc on this and has a data channel for receiving events that can be post-processed. The nice thing is that since the eBPF program and user space application making use of it are tightly coupled, they can define their own arbitrary raw data format and what/when they want to push. While f.e. packet headers could be one part of the meta data that is being pushed, this is not a substitute for things like packet sockets as whole packet is not being pushed and push is only done in a single direction. Intention is more of a generically usable, efficient event pipe to applications. Workflow is that tc can pin the map and applications can attach themselves e.g. after cls/act setup to one or multiple map slots, demuxing is done by the eBPF program. Adding this facility is with minimal effort, it reuses the helper introduced in a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") and we get its functionality for free by overloading its BPF_FUNC_ identifier for cls/act programs, ctx is currently unused, but will be made use of in future. Example will be added to iproute2's BPF example files. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-18 22:01:24 +03:00
}
bpf: add BPF_CALL_x macros for declaring helpers This work adds BPF_CALL_<n>() macros and converts all the eBPF helper functions to use them, in a similar fashion like we do with SYSCALL_DEFINE<n>() macros that are used today. Motivation for this is to hide all the register handling and all necessary casts from the user, so that it is done automatically in the background when adding a BPF_CALL_<n>() call. This makes current helpers easier to review, eases to write future helpers, avoids getting the casting mess wrong, and allows for extending all helpers at once (f.e. build time checks, etc). It also helps detecting more easily in code reviews that unused registers are not instrumented in the code by accident, breaking compatibility with existing programs. BPF_CALL_<n>() internals are quite similar to SYSCALL_DEFINE<n>() ones with some fundamental differences, for example, for generating the actual helper function that carries all u64 regs, we need to fill unused regs, so that we always end up with 5 u64 regs as an argument. I reviewed several 0-5 generated BPF_CALL_<n>() variants of the .i results and they look all as expected. No sparse issue spotted. We let this also sit for a few days with Fengguang's kbuild test robot, and there were no issues seen. On s390, it barked on the "uses dynamic stack allocation" notice, which is an old one from bpf_perf_event_output{,_tp}() reappearing here due to the conversion to the call wrapper, just telling that the perf raw record/frag sits on stack (gcc with s390's -mwarn-dynamicstack), but that's all. Did various runtime tests and they were fine as well. All eBPF helpers are now converted to use these macros, getting rid of a good chunk of all the raw castings. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-09 03:45:31 +03:00
BPF_CALL_0(bpf_get_current_task)
{
return (long) current;
}
const struct bpf_func_proto bpf_get_current_task_proto = {
.func = bpf_get_current_task,
.gpl_only = true,
.ret_type = RET_INTEGER,
};
bpf: add BPF_CALL_x macros for declaring helpers This work adds BPF_CALL_<n>() macros and converts all the eBPF helper functions to use them, in a similar fashion like we do with SYSCALL_DEFINE<n>() macros that are used today. Motivation for this is to hide all the register handling and all necessary casts from the user, so that it is done automatically in the background when adding a BPF_CALL_<n>() call. This makes current helpers easier to review, eases to write future helpers, avoids getting the casting mess wrong, and allows for extending all helpers at once (f.e. build time checks, etc). It also helps detecting more easily in code reviews that unused registers are not instrumented in the code by accident, breaking compatibility with existing programs. BPF_CALL_<n>() internals are quite similar to SYSCALL_DEFINE<n>() ones with some fundamental differences, for example, for generating the actual helper function that carries all u64 regs, we need to fill unused regs, so that we always end up with 5 u64 regs as an argument. I reviewed several 0-5 generated BPF_CALL_<n>() variants of the .i results and they look all as expected. No sparse issue spotted. We let this also sit for a few days with Fengguang's kbuild test robot, and there were no issues seen. On s390, it barked on the "uses dynamic stack allocation" notice, which is an old one from bpf_perf_event_output{,_tp}() reappearing here due to the conversion to the call wrapper, just telling that the perf raw record/frag sits on stack (gcc with s390's -mwarn-dynamicstack), but that's all. Did various runtime tests and they were fine as well. All eBPF helpers are now converted to use these macros, getting rid of a good chunk of all the raw castings. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-09 03:45:31 +03:00
BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
struct cgroup *cgrp;
if (unlikely(idx >= array->map.max_entries))
return -E2BIG;
cgrp = READ_ONCE(array->ptrs[idx]);
if (unlikely(!cgrp))
return -EAGAIN;
return task_under_cgroup_hierarchy(current, cgrp);
}
static const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
.func = bpf_current_task_under_cgroup,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_CONST_MAP_PTR,
.arg2_type = ARG_ANYTHING,
};
2019-05-24 00:47:45 +03:00
struct send_signal_irq_work {
struct irq_work irq_work;
struct task_struct *task;
u32 sig;
enum pid_type type;
2019-05-24 00:47:45 +03:00
};
static DEFINE_PER_CPU(struct send_signal_irq_work, send_signal_work);
static void do_bpf_send_signal(struct irq_work *entry)
{
struct send_signal_irq_work *work;
work = container_of(entry, struct send_signal_irq_work, irq_work);
group_send_sig_info(work->sig, SEND_SIG_PRIV, work->task, work->type);
2019-05-24 00:47:45 +03:00
}
static int bpf_send_signal_common(u32 sig, enum pid_type type)
2019-05-24 00:47:45 +03:00
{
struct send_signal_irq_work *work = NULL;
/* Similar to bpf_probe_write_user, task needs to be
* in a sound condition and kernel memory access be
* permitted in order to send signal to the current
* task.
*/
if (unlikely(current->flags & (PF_KTHREAD | PF_EXITING)))
return -EPERM;
if (unlikely(uaccess_kernel()))
return -EPERM;
if (unlikely(!nmi_uaccess_okay()))
return -EPERM;
bpf: Fix deadlock with rq_lock in bpf_send_signal() When experimenting with bpf_send_signal() helper in our production environment (5.2 based), we experienced a deadlock in NMI mode: #5 [ffffc9002219f770] queued_spin_lock_slowpath at ffffffff8110be24 #6 [ffffc9002219f770] _raw_spin_lock_irqsave at ffffffff81a43012 #7 [ffffc9002219f780] try_to_wake_up at ffffffff810e7ecd #8 [ffffc9002219f7e0] signal_wake_up_state at ffffffff810c7b55 #9 [ffffc9002219f7f0] __send_signal at ffffffff810c8602 #10 [ffffc9002219f830] do_send_sig_info at ffffffff810ca31a #11 [ffffc9002219f868] bpf_send_signal at ffffffff8119d227 #12 [ffffc9002219f988] bpf_overflow_handler at ffffffff811d4140 #13 [ffffc9002219f9e0] __perf_event_overflow at ffffffff811d68cf #14 [ffffc9002219fa10] perf_swevent_overflow at ffffffff811d6a09 #15 [ffffc9002219fa38] ___perf_sw_event at ffffffff811e0f47 #16 [ffffc9002219fc30] __schedule at ffffffff81a3e04d #17 [ffffc9002219fc90] schedule at ffffffff81a3e219 #18 [ffffc9002219fca0] futex_wait_queue_me at ffffffff8113d1b9 #19 [ffffc9002219fcd8] futex_wait at ffffffff8113e529 #20 [ffffc9002219fdf0] do_futex at ffffffff8113ffbc #21 [ffffc9002219fec0] __x64_sys_futex at ffffffff81140d1c #22 [ffffc9002219ff38] do_syscall_64 at ffffffff81002602 #23 [ffffc9002219ff50] entry_SYSCALL_64_after_hwframe at ffffffff81c00068 The above call stack is actually very similar to an issue reported by Commit eac9153f2b58 ("bpf/stackmap: Fix deadlock with rq_lock in bpf_get_stack()") by Song Liu. The only difference is bpf_send_signal() helper instead of bpf_get_stack() helper. The above deadlock is triggered with a perf_sw_event. Similar to Commit eac9153f2b58, the below almost identical reproducer used tracepoint point sched/sched_switch so the issue can be easily caught. /* stress_test.c */ #include <stdio.h> #include <stdlib.h> #include <sys/mman.h> #include <pthread.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #define THREAD_COUNT 1000 char *filename; void *worker(void *p) { void *ptr; int fd; char *pptr; fd = open(filename, O_RDONLY); if (fd < 0) return NULL; while (1) { struct timespec ts = {0, 1000 + rand() % 2000}; ptr = mmap(NULL, 4096 * 64, PROT_READ, MAP_PRIVATE, fd, 0); usleep(1); if (ptr == MAP_FAILED) { printf("failed to mmap\n"); break; } munmap(ptr, 4096 * 64); usleep(1); pptr = malloc(1); usleep(1); pptr[0] = 1; usleep(1); free(pptr); usleep(1); nanosleep(&ts, NULL); } close(fd); return NULL; } int main(int argc, char *argv[]) { void *ptr; int i; pthread_t threads[THREAD_COUNT]; if (argc < 2) return 0; filename = argv[1]; for (i = 0; i < THREAD_COUNT; i++) { if (pthread_create(threads + i, NULL, worker, NULL)) { fprintf(stderr, "Error creating thread\n"); return 0; } } for (i = 0; i < THREAD_COUNT; i++) pthread_join(threads[i], NULL); return 0; } and the following command: 1. run `stress_test /bin/ls` in one windown 2. hack bcc trace.py with the following change: --- a/tools/trace.py +++ b/tools/trace.py @@ -513,6 +513,7 @@ BPF_PERF_OUTPUT(%s); __data.tgid = __tgid; __data.pid = __pid; bpf_get_current_comm(&__data.comm, sizeof(__data.comm)); + bpf_send_signal(10); %s %s %s.perf_submit(%s, &__data, sizeof(__data)); 3. in a different window run ./trace.py -p $(pidof stress_test) t:sched:sched_switch The deadlock can be reproduced in our production system. Similar to Song's fix, the fix is to delay sending signal if irqs is disabled to avoid deadlocks involving with rq_lock. With this change, my above stress-test in our production system won't cause deadlock any more. I also implemented a scale-down version of reproducer in the selftest (a subsequent commit). With latest bpf-next, it complains for the following potential deadlock. [ 32.832450] -> #1 (&p->pi_lock){-.-.}: [ 32.833100] _raw_spin_lock_irqsave+0x44/0x80 [ 32.833696] task_rq_lock+0x2c/0xa0 [ 32.834182] task_sched_runtime+0x59/0xd0 [ 32.834721] thread_group_cputime+0x250/0x270 [ 32.835304] thread_group_cputime_adjusted+0x2e/0x70 [ 32.835959] do_task_stat+0x8a7/0xb80 [ 32.836461] proc_single_show+0x51/0xb0 ... [ 32.839512] -> #0 (&(&sighand->siglock)->rlock){....}: [ 32.840275] __lock_acquire+0x1358/0x1a20 [ 32.840826] lock_acquire+0xc7/0x1d0 [ 32.841309] _raw_spin_lock_irqsave+0x44/0x80 [ 32.841916] __lock_task_sighand+0x79/0x160 [ 32.842465] do_send_sig_info+0x35/0x90 [ 32.842977] bpf_send_signal+0xa/0x10 [ 32.843464] bpf_prog_bc13ed9e4d3163e3_send_signal_tp_sched+0x465/0x1000 [ 32.844301] trace_call_bpf+0x115/0x270 [ 32.844809] perf_trace_run_bpf_submit+0x4a/0xc0 [ 32.845411] perf_trace_sched_switch+0x10f/0x180 [ 32.846014] __schedule+0x45d/0x880 [ 32.846483] schedule+0x5f/0xd0 ... [ 32.853148] Chain exists of: [ 32.853148] &(&sighand->siglock)->rlock --> &p->pi_lock --> &rq->lock [ 32.853148] [ 32.854451] Possible unsafe locking scenario: [ 32.854451] [ 32.855173] CPU0 CPU1 [ 32.855745] ---- ---- [ 32.856278] lock(&rq->lock); [ 32.856671] lock(&p->pi_lock); [ 32.857332] lock(&rq->lock); [ 32.857999] lock(&(&sighand->siglock)->rlock); Deadlock happens on CPU0 when it tries to acquire &sighand->siglock but it has been held by CPU1 and CPU1 tries to grab &rq->lock and cannot get it. This is not exactly the callstack in our production environment, but sympotom is similar and both locks are using spin_lock_irqsave() to acquire the lock, and both involves rq_lock. The fix to delay sending signal when irq is disabled also fixed this issue. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Cc: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20200304191104.2796501-1-yhs@fb.com
2020-03-04 22:11:04 +03:00
if (irqs_disabled()) {
/* Do an early check on signal validity. Otherwise,
* the error is lost in deferred irq_work.
*/
if (unlikely(!valid_signal(sig)))
return -EINVAL;
2019-05-24 00:47:45 +03:00
work = this_cpu_ptr(&send_signal_work);
if (atomic_read(&work->irq_work.flags) & IRQ_WORK_BUSY)
2019-05-24 00:47:45 +03:00
return -EBUSY;
/* Add the current task, which is the target of sending signal,
* to the irq_work. The current task may change when queued
* irq works get executed.
*/
work->task = current;
work->sig = sig;
work->type = type;
2019-05-24 00:47:45 +03:00
irq_work_queue(&work->irq_work);
return 0;
}
return group_send_sig_info(sig, SEND_SIG_PRIV, current, type);
}
BPF_CALL_1(bpf_send_signal, u32, sig)
{
return bpf_send_signal_common(sig, PIDTYPE_TGID);
2019-05-24 00:47:45 +03:00
}
static const struct bpf_func_proto bpf_send_signal_proto = {
.func = bpf_send_signal,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_ANYTHING,
};
BPF_CALL_1(bpf_send_signal_thread, u32, sig)
{
return bpf_send_signal_common(sig, PIDTYPE_PID);
}
static const struct bpf_func_proto bpf_send_signal_thread_proto = {
.func = bpf_send_signal_thread,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_ANYTHING,
};
BPF_CALL_3(bpf_d_path, struct path *, path, char *, buf, u32, sz)
{
long len;
char *p;
if (!sz)
return 0;
p = d_path(path, buf, sz);
if (IS_ERR(p)) {
len = PTR_ERR(p);
} else {
len = buf + sz - p;
memmove(buf, p, len);
}
return len;
}
BTF_SET_START(btf_allowlist_d_path)
#ifdef CONFIG_SECURITY
BTF_ID(func, security_file_permission)
BTF_ID(func, security_inode_getattr)
BTF_ID(func, security_file_open)
#endif
#ifdef CONFIG_SECURITY_PATH
BTF_ID(func, security_path_truncate)
#endif
BTF_ID(func, vfs_truncate)
BTF_ID(func, vfs_fallocate)
BTF_ID(func, dentry_open)
BTF_ID(func, vfs_getattr)
BTF_ID(func, filp_close)
BTF_SET_END(btf_allowlist_d_path)
static bool bpf_d_path_allowed(const struct bpf_prog *prog)
{
return btf_id_set_contains(&btf_allowlist_d_path, prog->aux->attach_btf_id);
}
BTF_ID_LIST_SINGLE(bpf_d_path_btf_ids, struct, path)
static const struct bpf_func_proto bpf_d_path_proto = {
.func = bpf_d_path,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_BTF_ID,
.arg1_btf_id = &bpf_d_path_btf_ids[0],
.arg2_type = ARG_PTR_TO_MEM,
.arg3_type = ARG_CONST_SIZE_OR_ZERO,
.allowed = bpf_d_path_allowed,
};
bpf: Add bpf_snprintf_btf helper A helper is added to support tracing kernel type information in BPF using the BPF Type Format (BTF). Its signature is long bpf_snprintf_btf(char *str, u32 str_size, struct btf_ptr *ptr, u32 btf_ptr_size, u64 flags); struct btf_ptr * specifies - a pointer to the data to be traced - the BTF id of the type of data pointed to - a flags field is provided for future use; these flags are not to be confused with the BTF_F_* flags below that control how the btf_ptr is displayed; the flags member of the struct btf_ptr may be used to disambiguate types in kernel versus module BTF, etc; the main distinction is the flags relate to the type and information needed in identifying it; not how it is displayed. For example a BPF program with a struct sk_buff *skb could do the following: static struct btf_ptr b = { }; b.ptr = skb; b.type_id = __builtin_btf_type_id(struct sk_buff, 1); bpf_snprintf_btf(str, sizeof(str), &b, sizeof(b), 0, 0); Default output looks like this: (struct sk_buff){ .transport_header = (__u16)65535, .mac_header = (__u16)65535, .end = (sk_buff_data_t)192, .head = (unsigned char *)0x000000007524fd8b, .data = (unsigned char *)0x000000007524fd8b, .truesize = (unsigned int)768, .users = (refcount_t){ .refs = (atomic_t){ .counter = (int)1, }, }, } Flags modifying display are as follows: - BTF_F_COMPACT: no formatting around type information - BTF_F_NONAME: no struct/union member names/types - BTF_F_PTR_RAW: show raw (unobfuscated) pointer values; equivalent to %px. - BTF_F_ZERO: show zero-valued struct/union members; they are not displayed by default Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/1601292670-1616-4-git-send-email-alan.maguire@oracle.com
2020-09-28 14:31:05 +03:00
#define BTF_F_ALL (BTF_F_COMPACT | BTF_F_NONAME | \
BTF_F_PTR_RAW | BTF_F_ZERO)
static int bpf_btf_printf_prepare(struct btf_ptr *ptr, u32 btf_ptr_size,
u64 flags, const struct btf **btf,
s32 *btf_id)
{
const struct btf_type *t;
if (unlikely(flags & ~(BTF_F_ALL)))
return -EINVAL;
if (btf_ptr_size != sizeof(struct btf_ptr))
return -EINVAL;
*btf = bpf_get_btf_vmlinux();
if (IS_ERR_OR_NULL(*btf))
return PTR_ERR(*btf);
if (ptr->type_id > 0)
*btf_id = ptr->type_id;
else
return -EINVAL;
if (*btf_id > 0)
t = btf_type_by_id(*btf, *btf_id);
if (*btf_id <= 0 || !t)
return -ENOENT;
return 0;
}
BPF_CALL_5(bpf_snprintf_btf, char *, str, u32, str_size, struct btf_ptr *, ptr,
u32, btf_ptr_size, u64, flags)
{
const struct btf *btf;
s32 btf_id;
int ret;
ret = bpf_btf_printf_prepare(ptr, btf_ptr_size, flags, &btf, &btf_id);
if (ret)
return ret;
return btf_type_snprintf_show(btf, btf_id, ptr->ptr, str, str_size,
flags);
}
const struct bpf_func_proto bpf_snprintf_btf_proto = {
.func = bpf_snprintf_btf,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_MEM,
.arg2_type = ARG_CONST_SIZE,
.arg3_type = ARG_PTR_TO_MEM,
.arg4_type = ARG_CONST_SIZE,
.arg5_type = ARG_ANYTHING,
};
const struct bpf_func_proto *
bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
{
switch (func_id) {
case BPF_FUNC_map_lookup_elem:
return &bpf_map_lookup_elem_proto;
case BPF_FUNC_map_update_elem:
return &bpf_map_update_elem_proto;
case BPF_FUNC_map_delete_elem:
return &bpf_map_delete_elem_proto;
case BPF_FUNC_map_push_elem:
return &bpf_map_push_elem_proto;
case BPF_FUNC_map_pop_elem:
return &bpf_map_pop_elem_proto;
case BPF_FUNC_map_peek_elem:
return &bpf_map_peek_elem_proto;
case BPF_FUNC_ktime_get_ns:
return &bpf_ktime_get_ns_proto;
case BPF_FUNC_ktime_get_boot_ns:
return &bpf_ktime_get_boot_ns_proto;
bpf: allow bpf programs to tail-call other bpf programs introduce bpf_tail_call(ctx, &jmp_table, index) helper function which can be used from BPF programs like: int bpf_prog(struct pt_regs *ctx) { ... bpf_tail_call(ctx, &jmp_table, index); ... } that is roughly equivalent to: int bpf_prog(struct pt_regs *ctx) { ... if (jmp_table[index]) return (*jmp_table[index])(ctx); ... } The important detail that it's not a normal call, but a tail call. The kernel stack is precious, so this helper reuses the current stack frame and jumps into another BPF program without adding extra call frame. It's trivially done in interpreter and a bit trickier in JITs. In case of x64 JIT the bigger part of generated assembler prologue is common for all programs, so it is simply skipped while jumping. Other JITs can do similar prologue-skipping optimization or do stack unwind before jumping into the next program. bpf_tail_call() arguments: ctx - context pointer jmp_table - one of BPF_MAP_TYPE_PROG_ARRAY maps used as the jump table index - index in the jump table Since all BPF programs are idenitified by file descriptor, user space need to populate the jmp_table with FDs of other BPF programs. If jmp_table[index] is empty the bpf_tail_call() doesn't jump anywhere and program execution continues as normal. New BPF_MAP_TYPE_PROG_ARRAY map type is introduced so that user space can populate this jmp_table array with FDs of other bpf programs. Programs can share the same jmp_table array or use multiple jmp_tables. The chain of tail calls can form unpredictable dynamic loops therefore tail_call_cnt is used to limit the number of calls and currently is set to 32. Use cases: Acked-by: Daniel Borkmann <daniel@iogearbox.net> ========== - simplify complex programs by splitting them into a sequence of small programs - dispatch routine For tracing and future seccomp the program may be triggered on all system calls, but processing of syscall arguments will be different. It's more efficient to implement them as: int syscall_entry(struct seccomp_data *ctx) { bpf_tail_call(ctx, &syscall_jmp_table, ctx->nr /* syscall number */); ... default: process unknown syscall ... } int sys_write_event(struct seccomp_data *ctx) {...} int sys_read_event(struct seccomp_data *ctx) {...} syscall_jmp_table[__NR_write] = sys_write_event; syscall_jmp_table[__NR_read] = sys_read_event; For networking the program may call into different parsers depending on packet format, like: int packet_parser(struct __sk_buff *skb) { ... parse L2, L3 here ... __u8 ipproto = load_byte(skb, ... offsetof(struct iphdr, protocol)); bpf_tail_call(skb, &ipproto_jmp_table, ipproto); ... default: process unknown protocol ... } int parse_tcp(struct __sk_buff *skb) {...} int parse_udp(struct __sk_buff *skb) {...} ipproto_jmp_table[IPPROTO_TCP] = parse_tcp; ipproto_jmp_table[IPPROTO_UDP] = parse_udp; - for TC use case, bpf_tail_call() allows to implement reclassify-like logic - bpf_map_update_elem/delete calls into BPF_MAP_TYPE_PROG_ARRAY jump table are atomic, so user space can build chains of BPF programs on the fly Implementation details: ======================= - high performance of bpf_tail_call() is the goal. It could have been implemented without JIT changes as a wrapper on top of BPF_PROG_RUN() macro, but with two downsides: . all programs would have to pay performance penalty for this feature and tail call itself would be slower, since mandatory stack unwind, return, stack allocate would be done for every tailcall. . tailcall would be limited to programs running preempt_disabled, since generic 'void *ctx' doesn't have room for 'tail_call_cnt' and it would need to be either global per_cpu variable accessed by helper and by wrapper or global variable protected by locks. In this implementation x64 JIT bypasses stack unwind and jumps into the callee program after prologue. - bpf_prog_array_compatible() ensures that prog_type of callee and caller are the same and JITed/non-JITed flag is the same, since calling JITed program from non-JITed is invalid, since stack frames are different. Similarly calling kprobe type program from socket type program is invalid. - jump table is implemented as BPF_MAP_TYPE_PROG_ARRAY to reuse 'map' abstraction, its user space API and all of verifier logic. It's in the existing arraymap.c file, since several functions are shared with regular array map. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-20 02:59:03 +03:00
case BPF_FUNC_tail_call:
return &bpf_tail_call_proto;
case BPF_FUNC_get_current_pid_tgid:
return &bpf_get_current_pid_tgid_proto;
case BPF_FUNC_get_current_task:
return &bpf_get_current_task_proto;
case BPF_FUNC_get_current_uid_gid:
return &bpf_get_current_uid_gid_proto;
case BPF_FUNC_get_current_comm:
return &bpf_get_current_comm_proto;
case BPF_FUNC_trace_printk:
return bpf_get_trace_printk_proto();
case BPF_FUNC_get_smp_processor_id:
return &bpf_get_smp_processor_id_proto;
case BPF_FUNC_get_numa_node_id:
return &bpf_get_numa_node_id_proto;
case BPF_FUNC_perf_event_read:
return &bpf_perf_event_read_proto;
case BPF_FUNC_probe_write_user:
return bpf_get_probe_write_proto();
case BPF_FUNC_current_task_under_cgroup:
return &bpf_current_task_under_cgroup_proto;
case BPF_FUNC_get_prandom_u32:
return &bpf_get_prandom_u32_proto;
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
case BPF_FUNC_probe_read_user:
return &bpf_probe_read_user_proto;
case BPF_FUNC_probe_read_kernel:
return &bpf_probe_read_kernel_proto;
case BPF_FUNC_probe_read_user_str:
return &bpf_probe_read_user_str_proto;
case BPF_FUNC_probe_read_kernel_str:
return &bpf_probe_read_kernel_str_proto;
bpf: Restrict bpf_probe_read{, str}() only to archs where they work Given the legacy bpf_probe_read{,str}() BPF helpers are broken on archs with overlapping address ranges, we should really take the next step to disable them from BPF use there. To generally fix the situation, we've recently added new helper variants bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str(). For details on them, see 6ae08ae3dea2 ("bpf: Add probe_read_{user, kernel} and probe_read_{user,kernel}_str helpers"). Given bpf_probe_read{,str}() have been around for ~5 years by now, there are plenty of users at least on x86 still relying on them today, so we cannot remove them entirely w/o breaking the BPF tracing ecosystem. However, their use should be restricted to archs with non-overlapping address ranges where they are working in their current form. Therefore, move this behind a CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE and have x86, arm64, arm select it (other archs supporting it can follow-up on it as well). For the remaining archs, they can workaround easily by relying on the feature probe from bpftool which spills out defines that can be used out of BPF C code to implement the drop-in replacement for old/new kernels via: bpftool feature probe macro Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Brendan Gregg <brendan.d.gregg@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/bpf/20200515101118.6508-2-daniel@iogearbox.net
2020-05-15 13:11:16 +03:00
#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
case BPF_FUNC_probe_read:
return &bpf_probe_read_compat_proto;
bpf: add bpf_probe_read_str helper Provide a simple helper with the same semantics of strncpy_from_unsafe(): int bpf_probe_read_str(void *dst, int size, const void *unsafe_addr) This gives more flexibility to a bpf program. A typical use case is intercepting a file name during sys_open(). The current approach is: SEC("kprobe/sys_open") void bpf_sys_open(struct pt_regs *ctx) { char buf[PATHLEN]; // PATHLEN is defined to 256 bpf_probe_read(buf, sizeof(buf), ctx->di); /* consume buf */ } This is suboptimal because the size of the string needs to be estimated at compile time, causing more memory to be copied than often necessary, and can become more problematic if further processing on buf is done, for example by pushing it to userspace via bpf_perf_event_output(), since the real length of the string is unknown and the entire buffer must be copied (and defining an unrolled strnlen() inside the bpf program is a very inefficient and unfeasible approach). With the new helper, the code can easily operate on the actual string length rather than the buffer size: SEC("kprobe/sys_open") void bpf_sys_open(struct pt_regs *ctx) { char buf[PATHLEN]; // PATHLEN is defined to 256 int res = bpf_probe_read_str(buf, sizeof(buf), ctx->di); /* consume buf, for example push it to userspace via * bpf_perf_event_output(), but this time we can use * res (the string length) as event size, after checking * its boundaries. */ } Another useful use case is when parsing individual process arguments or individual environment variables navigating current->mm->arg_start and current->mm->env_start: using this helper and the return value, one can quickly iterate at the right offset of the memory area. The code changes simply leverage the already existent strncpy_from_unsafe() kernel function, which is safe to be called from a bpf program as it is used in bpf_trace_printk(). Signed-off-by: Gianluca Borello <g.borello@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-18 20:55:49 +03:00
case BPF_FUNC_probe_read_str:
bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers The current bpf_probe_read() and bpf_probe_read_str() helpers are broken in that they assume they can be used for probing memory access for kernel space addresses /as well as/ user space addresses. However, plain use of probe_kernel_read() for both cases will attempt to always access kernel space address space given access is performed under KERNEL_DS and some archs in-fact have overlapping address spaces where a kernel pointer and user pointer would have the /same/ address value and therefore accessing application memory via bpf_probe_read{,_str}() would read garbage values. Lets fix BPF side by making use of recently added 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions"). Unfortunately, the only way to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}() helpers are kept as-is to retain their current behavior. The two *_user() variants attempt the access always under USER_DS set, the two *_kernel() variants will -EFAULT when accessing user memory if the underlying architecture has non-overlapping address ranges, also avoiding throwing the kernel warning via 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). Fixes: a5e8c07059d0 ("bpf: add bpf_probe_read_str helper") Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
2019-11-02 02:17:59 +03:00
return &bpf_probe_read_compat_str_proto;
bpf: Restrict bpf_probe_read{, str}() only to archs where they work Given the legacy bpf_probe_read{,str}() BPF helpers are broken on archs with overlapping address ranges, we should really take the next step to disable them from BPF use there. To generally fix the situation, we've recently added new helper variants bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str(). For details on them, see 6ae08ae3dea2 ("bpf: Add probe_read_{user, kernel} and probe_read_{user,kernel}_str helpers"). Given bpf_probe_read{,str}() have been around for ~5 years by now, there are plenty of users at least on x86 still relying on them today, so we cannot remove them entirely w/o breaking the BPF tracing ecosystem. However, their use should be restricted to archs with non-overlapping address ranges where they are working in their current form. Therefore, move this behind a CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE and have x86, arm64, arm select it (other archs supporting it can follow-up on it as well). For the remaining archs, they can workaround easily by relying on the feature probe from bpftool which spills out defines that can be used out of BPF C code to implement the drop-in replacement for old/new kernels via: bpftool feature probe macro Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Brendan Gregg <brendan.d.gregg@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/bpf/20200515101118.6508-2-daniel@iogearbox.net
2020-05-15 13:11:16 +03:00
#endif
#ifdef CONFIG_CGROUPS
case BPF_FUNC_get_current_cgroup_id:
return &bpf_get_current_cgroup_id_proto;
#endif
2019-05-24 00:47:45 +03:00
case BPF_FUNC_send_signal:
return &bpf_send_signal_proto;
case BPF_FUNC_send_signal_thread:
return &bpf_send_signal_thread_proto;
case BPF_FUNC_perf_event_read_value:
return &bpf_perf_event_read_value_proto;
case BPF_FUNC_get_ns_current_pid_tgid:
return &bpf_get_ns_current_pid_tgid_proto;
bpf: Implement BPF ring buffer and verifier support for it This commit adds a new MPSC ring buffer implementation into BPF ecosystem, which allows multiple CPUs to submit data to a single shared ring buffer. On the consumption side, only single consumer is assumed. Motivation ---------- There are two distinctive motivators for this work, which are not satisfied by existing perf buffer, which prompted creation of a new ring buffer implementation. - more efficient memory utilization by sharing ring buffer across CPUs; - preserving ordering of events that happen sequentially in time, even across multiple CPUs (e.g., fork/exec/exit events for a task). These two problems are independent, but perf buffer fails to satisfy both. Both are a result of a choice to have per-CPU perf ring buffer. Both can be also solved by having an MPSC implementation of ring buffer. The ordering problem could technically be solved for perf buffer with some in-kernel counting, but given the first one requires an MPSC buffer, the same solution would solve the second problem automatically. Semantics and APIs ------------------ Single ring buffer is presented to BPF programs as an instance of BPF map of type BPF_MAP_TYPE_RINGBUF. Two other alternatives considered, but ultimately rejected. One way would be to, similar to BPF_MAP_TYPE_PERF_EVENT_ARRAY, make BPF_MAP_TYPE_RINGBUF could represent an array of ring buffers, but not enforce "same CPU only" rule. This would be more familiar interface compatible with existing perf buffer use in BPF, but would fail if application needed more advanced logic to lookup ring buffer by arbitrary key. HASH_OF_MAPS addresses this with current approach. Additionally, given the performance of BPF ringbuf, many use cases would just opt into a simple single ring buffer shared among all CPUs, for which current approach would be an overkill. Another approach could introduce a new concept, alongside BPF map, to represent generic "container" object, which doesn't necessarily have key/value interface with lookup/update/delete operations. This approach would add a lot of extra infrastructure that has to be built for observability and verifier support. It would also add another concept that BPF developers would have to familiarize themselves with, new syntax in libbpf, etc. But then would really provide no additional benefits over the approach of using a map. BPF_MAP_TYPE_RINGBUF doesn't support lookup/update/delete operations, but so doesn't few other map types (e.g., queue and stack; array doesn't support delete, etc). The approach chosen has an advantage of re-using existing BPF map infrastructure (introspection APIs in kernel, libbpf support, etc), being familiar concept (no need to teach users a new type of object in BPF program), and utilizing existing tooling (bpftool). For common scenario of using a single ring buffer for all CPUs, it's as simple and straightforward, as would be with a dedicated "container" object. On the other hand, by being a map, it can be combined with ARRAY_OF_MAPS and HASH_OF_MAPS map-in-maps to implement a wide variety of topologies, from one ring buffer for each CPU (e.g., as a replacement for perf buffer use cases), to a complicated application hashing/sharding of ring buffers (e.g., having a small pool of ring buffers with hashed task's tgid being a look up key to preserve order, but reduce contention). Key and value sizes are enforced to be zero. max_entries is used to specify the size of ring buffer and has to be a power of 2 value. There are a bunch of similarities between perf buffer (BPF_MAP_TYPE_PERF_EVENT_ARRAY) and new BPF ring buffer semantics: - variable-length records; - if there is no more space left in ring buffer, reservation fails, no blocking; - memory-mappable data area for user-space applications for ease of consumption and high performance; - epoll notifications for new incoming data; - but still the ability to do busy polling for new data to achieve the lowest latency, if necessary. BPF ringbuf provides two sets of APIs to BPF programs: - bpf_ringbuf_output() allows to *copy* data from one place to a ring buffer, similarly to bpf_perf_event_output(); - bpf_ringbuf_reserve()/bpf_ringbuf_commit()/bpf_ringbuf_discard() APIs split the whole process into two steps. First, a fixed amount of space is reserved. If successful, a pointer to a data inside ring buffer data area is returned, which BPF programs can use similarly to a data inside array/hash maps. Once ready, this piece of memory is either committed or discarded. Discard is similar to commit, but makes consumer ignore the record. bpf_ringbuf_output() has disadvantage of incurring extra memory copy, because record has to be prepared in some other place first. But it allows to submit records of the length that's not known to verifier beforehand. It also closely matches bpf_perf_event_output(), so will simplify migration significantly. bpf_ringbuf_reserve() avoids the extra copy of memory by providing a memory pointer directly to ring buffer memory. In a lot of cases records are larger than BPF stack space allows, so many programs have use extra per-CPU array as a temporary heap for preparing sample. bpf_ringbuf_reserve() avoid this needs completely. But in exchange, it only allows a known constant size of memory to be reserved, such that verifier can verify that BPF program can't access memory outside its reserved record space. bpf_ringbuf_output(), while slightly slower due to extra memory copy, covers some use cases that are not suitable for bpf_ringbuf_reserve(). The difference between commit and discard is very small. Discard just marks a record as discarded, and such records are supposed to be ignored by consumer code. Discard is useful for some advanced use-cases, such as ensuring all-or-nothing multi-record submission, or emulating temporary malloc()/free() within single BPF program invocation. Each reserved record is tracked by verifier through existing reference-tracking logic, similar to socket ref-tracking. It is thus impossible to reserve a record, but forget to submit (or discard) it. bpf_ringbuf_query() helper allows to query various properties of ring buffer. Currently 4 are supported: - BPF_RB_AVAIL_DATA returns amount of unconsumed data in ring buffer; - BPF_RB_RING_SIZE returns the size of ring buffer; - BPF_RB_CONS_POS/BPF_RB_PROD_POS returns current logical possition of consumer/producer, respectively. Returned values are momentarily snapshots of ring buffer state and could be off by the time helper returns, so this should be used only for debugging/reporting reasons or for implementing various heuristics, that take into account highly-changeable nature of some of those characteristics. One such heuristic might involve more fine-grained control over poll/epoll notifications about new data availability in ring buffer. Together with BPF_RB_NO_WAKEUP/BPF_RB_FORCE_WAKEUP flags for output/commit/discard helpers, it allows BPF program a high degree of control and, e.g., more efficient batched notifications. Default self-balancing strategy, though, should be adequate for most applications and will work reliable and efficiently already. Design and implementation ------------------------- This reserve/commit schema allows a natural way for multiple producers, either on different CPUs or even on the same CPU/in the same BPF program, to reserve independent records and work with them without blocking other producers. This means that if BPF program was interruped by another BPF program sharing the same ring buffer, they will both get a record reserved (provided there is enough space left) and can work with it and submit it independently. This applies to NMI context as well, except that due to using a spinlock during reservation, in NMI context, bpf_ringbuf_reserve() might fail to get a lock, in which case reservation will fail even if ring buffer is not full. The ring buffer itself internally is implemented as a power-of-2 sized circular buffer, with two logical and ever-increasing counters (which might wrap around on 32-bit architectures, that's not a problem): - consumer counter shows up to which logical position consumer consumed the data; - producer counter denotes amount of data reserved by all producers. Each time a record is reserved, producer that "owns" the record will successfully advance producer counter. At that point, data is still not yet ready to be consumed, though. Each record has 8 byte header, which contains the length of reserved record, as well as two extra bits: busy bit to denote that record is still being worked on, and discard bit, which might be set at commit time if record is discarded. In the latter case, consumer is supposed to skip the record and move on to the next one. Record header also encodes record's relative offset from the beginning of ring buffer data area (in pages). This allows bpf_ringbuf_commit()/bpf_ringbuf_discard() to accept only the pointer to the record itself, without requiring also the pointer to ring buffer itself. Ring buffer memory location will be restored from record metadata header. This significantly simplifies verifier, as well as improving API usability. Producer counter increments are serialized under spinlock, so there is a strict ordering between reservations. Commits, on the other hand, are completely lockless and independent. All records become available to consumer in the order of reservations, but only after all previous records where already committed. It is thus possible for slow producers to temporarily hold off submitted records, that were reserved later. Reservation/commit/consumer protocol is verified by litmus tests in Documentation/litmus-test/bpf-rb. One interesting implementation bit, that significantly simplifies (and thus speeds up as well) implementation of both producers and consumers is how data area is mapped twice contiguously back-to-back in the virtual memory. This allows to not take any special measures for samples that have to wrap around at the end of the circular buffer data area, because the next page after the last data page would be first data page again, and thus the sample will still appear completely contiguous in virtual memory. See comment and a simple ASCII diagram showing this visually in bpf_ringbuf_area_alloc(). Another feature that distinguishes BPF ringbuf from perf ring buffer is a self-pacing notifications of new data being availability. bpf_ringbuf_commit() implementation will send a notification of new record being available after commit only if consumer has already caught up right up to the record being committed. If not, consumer still has to catch up and thus will see new data anyways without needing an extra poll notification. Benchmarks (see tools/testing/selftests/bpf/benchs/bench_ringbuf.c) show that this allows to achieve a very high throughput without having to resort to tricks like "notify only every Nth sample", which are necessary with perf buffer. For extreme cases, when BPF program wants more manual control of notifications, commit/discard/output helpers accept BPF_RB_NO_WAKEUP and BPF_RB_FORCE_WAKEUP flags, which give full control over notifications of data availability, but require extra caution and diligence in using this API. Comparison to alternatives -------------------------- Before considering implementing BPF ring buffer from scratch existing alternatives in kernel were evaluated, but didn't seem to meet the needs. They largely fell into few categores: - per-CPU buffers (perf, ftrace, etc), which don't satisfy two motivations outlined above (ordering and memory consumption); - linked list-based implementations; while some were multi-producer designs, consuming these from user-space would be very complicated and most probably not performant; memory-mapping contiguous piece of memory is simpler and more performant for user-space consumers; - io_uring is SPSC, but also requires fixed-sized elements. Naively turning SPSC queue into MPSC w/ lock would have subpar performance compared to locked reserve + lockless commit, as with BPF ring buffer. Fixed sized elements would be too limiting for BPF programs, given existing BPF programs heavily rely on variable-sized perf buffer already; - specialized implementations (like a new printk ring buffer, [0]) with lots of printk-specific limitations and implications, that didn't seem to fit well for intended use with BPF programs. [0] https://lwn.net/Articles/779550/ Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200529075424.3139988-2-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-05-29 10:54:20 +03:00
case BPF_FUNC_ringbuf_output:
return &bpf_ringbuf_output_proto;
case BPF_FUNC_ringbuf_reserve:
return &bpf_ringbuf_reserve_proto;
case BPF_FUNC_ringbuf_submit:
return &bpf_ringbuf_submit_proto;
case BPF_FUNC_ringbuf_discard:
return &bpf_ringbuf_discard_proto;
case BPF_FUNC_ringbuf_query:
return &bpf_ringbuf_query_proto;
case BPF_FUNC_jiffies64:
return &bpf_jiffies64_proto;
case BPF_FUNC_get_task_stack:
return &bpf_get_task_stack_proto;
case BPF_FUNC_copy_from_user:
return prog->aux->sleepable ? &bpf_copy_from_user_proto : NULL;
bpf: Add bpf_snprintf_btf helper A helper is added to support tracing kernel type information in BPF using the BPF Type Format (BTF). Its signature is long bpf_snprintf_btf(char *str, u32 str_size, struct btf_ptr *ptr, u32 btf_ptr_size, u64 flags); struct btf_ptr * specifies - a pointer to the data to be traced - the BTF id of the type of data pointed to - a flags field is provided for future use; these flags are not to be confused with the BTF_F_* flags below that control how the btf_ptr is displayed; the flags member of the struct btf_ptr may be used to disambiguate types in kernel versus module BTF, etc; the main distinction is the flags relate to the type and information needed in identifying it; not how it is displayed. For example a BPF program with a struct sk_buff *skb could do the following: static struct btf_ptr b = { }; b.ptr = skb; b.type_id = __builtin_btf_type_id(struct sk_buff, 1); bpf_snprintf_btf(str, sizeof(str), &b, sizeof(b), 0, 0); Default output looks like this: (struct sk_buff){ .transport_header = (__u16)65535, .mac_header = (__u16)65535, .end = (sk_buff_data_t)192, .head = (unsigned char *)0x000000007524fd8b, .data = (unsigned char *)0x000000007524fd8b, .truesize = (unsigned int)768, .users = (refcount_t){ .refs = (atomic_t){ .counter = (int)1, }, }, } Flags modifying display are as follows: - BTF_F_COMPACT: no formatting around type information - BTF_F_NONAME: no struct/union member names/types - BTF_F_PTR_RAW: show raw (unobfuscated) pointer values; equivalent to %px. - BTF_F_ZERO: show zero-valued struct/union members; they are not displayed by default Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/1601292670-1616-4-git-send-email-alan.maguire@oracle.com
2020-09-28 14:31:05 +03:00
case BPF_FUNC_snprintf_btf:
return &bpf_snprintf_btf_proto;
case BPF_FUNC_bpf_per_cpu_ptr:
return &bpf_per_cpu_ptr_proto;
case BPF_FUNC_bpf_this_cpu_ptr:
return &bpf_this_cpu_ptr_proto;
default:
return NULL;
}
}
bpf: Check attach type at prog load time == The problem == There are use-cases when a program of some type can be attached to multiple attach points and those attach points must have different permissions to access context or to call helpers. E.g. context structure may have fields for both IPv4 and IPv6 but it doesn't make sense to read from / write to IPv6 field when attach point is somewhere in IPv4 stack. Same applies to BPF-helpers: it may make sense to call some helper from some attach point, but not from other for same prog type. == The solution == Introduce `expected_attach_type` field in in `struct bpf_attr` for `BPF_PROG_LOAD` command. If scenario described in "The problem" section is the case for some prog type, the field will be checked twice: 1) At load time prog type is checked to see if attach type for it must be known to validate program permissions correctly. Prog will be rejected with EINVAL if it's the case and `expected_attach_type` is not specified or has invalid value. 2) At attach time `attach_type` is compared with `expected_attach_type`, if prog type requires to have one, and, if they differ, attach will be rejected with EINVAL. The `expected_attach_type` is now available as part of `struct bpf_prog` in both `bpf_verifier_ops->is_valid_access()` and `bpf_verifier_ops->get_func_proto()` () and can be used to check context accesses and calls to helpers correspondingly. Initially the idea was discussed by Alexei Starovoitov <ast@fb.com> and Daniel Borkmann <daniel@iogearbox.net> here: https://marc.info/?l=linux-netdev&m=152107378717201&w=2 Signed-off-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-31 01:08:00 +03:00
static const struct bpf_func_proto *
kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
switch (func_id) {
case BPF_FUNC_perf_event_output:
return &bpf_perf_event_output_proto;
case BPF_FUNC_get_stackid:
return &bpf_get_stackid_proto;
case BPF_FUNC_get_stack:
return &bpf_get_stack_proto;
#ifdef CONFIG_BPF_KPROBE_OVERRIDE
case BPF_FUNC_override_return:
return &bpf_override_return_proto;
#endif
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
default:
return bpf_tracing_func_proto(func_id, prog);
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
}
}
/* bpf+kprobe programs can access fields of 'struct pt_regs' */
static bool kprobe_prog_is_valid_access(int off, int size, enum bpf_access_type type,
bpf: Check attach type at prog load time == The problem == There are use-cases when a program of some type can be attached to multiple attach points and those attach points must have different permissions to access context or to call helpers. E.g. context structure may have fields for both IPv4 and IPv6 but it doesn't make sense to read from / write to IPv6 field when attach point is somewhere in IPv4 stack. Same applies to BPF-helpers: it may make sense to call some helper from some attach point, but not from other for same prog type. == The solution == Introduce `expected_attach_type` field in in `struct bpf_attr` for `BPF_PROG_LOAD` command. If scenario described in "The problem" section is the case for some prog type, the field will be checked twice: 1) At load time prog type is checked to see if attach type for it must be known to validate program permissions correctly. Prog will be rejected with EINVAL if it's the case and `expected_attach_type` is not specified or has invalid value. 2) At attach time `attach_type` is compared with `expected_attach_type`, if prog type requires to have one, and, if they differ, attach will be rejected with EINVAL. The `expected_attach_type` is now available as part of `struct bpf_prog` in both `bpf_verifier_ops->is_valid_access()` and `bpf_verifier_ops->get_func_proto()` () and can be used to check context accesses and calls to helpers correspondingly. Initially the idea was discussed by Alexei Starovoitov <ast@fb.com> and Daniel Borkmann <daniel@iogearbox.net> here: https://marc.info/?l=linux-netdev&m=152107378717201&w=2 Signed-off-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-31 01:08:00 +03:00
const struct bpf_prog *prog,
struct bpf_insn_access_aux *info)
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
{
if (off < 0 || off >= sizeof(struct pt_regs))
return false;
if (type != BPF_READ)
return false;
if (off % size != 0)
return false;
/*
* Assertion for 32 bit to make sure last 8 byte access
* (BPF_DW) to the last 4 byte member is disallowed.
*/
if (off + size > sizeof(struct pt_regs))
return false;
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
return true;
}
const struct bpf_verifier_ops kprobe_verifier_ops = {
tracing, perf: Implement BPF programs attached to kprobes BPF programs, attached to kprobes, provide a safe way to execute user-defined BPF byte-code programs without being able to crash or hang the kernel in any way. The BPF engine makes sure that such programs have a finite execution time and that they cannot break out of their sandbox. The user interface is to attach to a kprobe via the perf syscall: struct perf_event_attr attr = { .type = PERF_TYPE_TRACEPOINT, .config = event_id, ... }; event_fd = perf_event_open(&attr,...); ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); 'prog_fd' is a file descriptor associated with BPF program previously loaded. 'event_id' is an ID of the kprobe created. Closing 'event_fd': close(event_fd); ... automatically detaches BPF program from it. BPF programs can call in-kernel helper functions to: - lookup/update/delete elements in maps - probe_read - wraper of probe_kernel_read() used to access any kernel data structures BPF programs receive 'struct pt_regs *' as an input ('struct pt_regs' is architecture dependent) and return 0 to ignore the event and 1 to store kprobe event into the ring buffer. Note, kprobes are a fundamentally _not_ a stable kernel ABI, so BPF programs attached to kprobes must be recompiled for every kernel version and user must supply correct LINUX_VERSION_CODE in attr.kern_version during bpf_prog_load() call. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 22:49:20 +03:00
.get_func_proto = kprobe_prog_func_proto,
.is_valid_access = kprobe_prog_is_valid_access,
};
const struct bpf_prog_ops kprobe_prog_ops = {
};
bpf: add BPF_CALL_x macros for declaring helpers This work adds BPF_CALL_<n>() macros and converts all the eBPF helper functions to use them, in a similar fashion like we do with SYSCALL_DEFINE<n>() macros that are used today. Motivation for this is to hide all the register handling and all necessary casts from the user, so that it is done automatically in the background when adding a BPF_CALL_<n>() call. This makes current helpers easier to review, eases to write future helpers, avoids getting the casting mess wrong, and allows for extending all helpers at once (f.e. build time checks, etc). It also helps detecting more easily in code reviews that unused registers are not instrumented in the code by accident, breaking compatibility with existing programs. BPF_CALL_<n>() internals are quite similar to SYSCALL_DEFINE<n>() ones with some fundamental differences, for example, for generating the actual helper function that carries all u64 regs, we need to fill unused regs, so that we always end up with 5 u64 regs as an argument. I reviewed several 0-5 generated BPF_CALL_<n>() variants of the .i results and they look all as expected. No sparse issue spotted. We let this also sit for a few days with Fengguang's kbuild test robot, and there were no issues seen. On s390, it barked on the "uses dynamic stack allocation" notice, which is an old one from bpf_perf_event_output{,_tp}() reappearing here due to the conversion to the call wrapper, just telling that the perf raw record/frag sits on stack (gcc with s390's -mwarn-dynamicstack), but that's all. Did various runtime tests and they were fine as well. All eBPF helpers are now converted to use these macros, getting rid of a good chunk of all the raw castings. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-09 03:45:31 +03:00
BPF_CALL_5(bpf_perf_event_output_tp, void *, tp_buff, struct bpf_map *, map,
u64, flags, void *, data, u64, size)
{
bpf: add BPF_CALL_x macros for declaring helpers This work adds BPF_CALL_<n>() macros and converts all the eBPF helper functions to use them, in a similar fashion like we do with SYSCALL_DEFINE<n>() macros that are used today. Motivation for this is to hide all the register handling and all necessary casts from the user, so that it is done automatically in the background when adding a BPF_CALL_<n>() call. This makes current helpers easier to review, eases to write future helpers, avoids getting the casting mess wrong, and allows for extending all helpers at once (f.e. build time checks, etc). It also helps detecting more easily in code reviews that unused registers are not instrumented in the code by accident, breaking compatibility with existing programs. BPF_CALL_<n>() internals are quite similar to SYSCALL_DEFINE<n>() ones with some fundamental differences, for example, for generating the actual helper function that carries all u64 regs, we need to fill unused regs, so that we always end up with 5 u64 regs as an argument. I reviewed several 0-5 generated BPF_CALL_<n>() variants of the .i results and they look all as expected. No sparse issue spotted. We let this also sit for a few days with Fengguang's kbuild test robot, and there were no issues seen. On s390, it barked on the "uses dynamic stack allocation" notice, which is an old one from bpf_perf_event_output{,_tp}() reappearing here due to the conversion to the call wrapper, just telling that the perf raw record/frag sits on stack (gcc with s390's -mwarn-dynamicstack), but that's all. Did various runtime tests and they were fine as well. All eBPF helpers are now converted to use these macros, getting rid of a good chunk of all the raw castings. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-09 03:45:31 +03:00
struct pt_regs *regs = *(struct pt_regs **)tp_buff;
/*
* r1 points to perf tracepoint buffer where first 8 bytes are hidden
* from bpf program and contain a pointer to 'struct pt_regs'. Fetch it
bpf: add BPF_CALL_x macros for declaring helpers This work adds BPF_CALL_<n>() macros and converts all the eBPF helper functions to use them, in a similar fashion like we do with SYSCALL_DEFINE<n>() macros that are used today. Motivation for this is to hide all the register handling and all necessary casts from the user, so that it is done automatically in the background when adding a BPF_CALL_<n>() call. This makes current helpers easier to review, eases to write future helpers, avoids getting the casting mess wrong, and allows for extending all helpers at once (f.e. build time checks, etc). It also helps detecting more easily in code reviews that unused registers are not instrumented in the code by accident, breaking compatibility with existing programs. BPF_CALL_<n>() internals are quite similar to SYSCALL_DEFINE<n>() ones with some fundamental differences, for example, for generating the actual helper function that carries all u64 regs, we need to fill unused regs, so that we always end up with 5 u64 regs as an argument. I reviewed several 0-5 generated BPF_CALL_<n>() variants of the .i results and they look all as expected. No sparse issue spotted. We let this also sit for a few days with Fengguang's kbuild test robot, and there were no issues seen. On s390, it barked on the "uses dynamic stack allocation" notice, which is an old one from bpf_perf_event_output{,_tp}() reappearing here due to the conversion to the call wrapper, just telling that the perf raw record/frag sits on stack (gcc with s390's -mwarn-dynamicstack), but that's all. Did various runtime tests and they were fine as well. All eBPF helpers are now converted to use these macros, getting rid of a good chunk of all the raw castings. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-09 03:45:31 +03:00
* from there and call the same bpf_perf_event_output() helper inline.
*/
bpf: add BPF_CALL_x macros for declaring helpers This work adds BPF_CALL_<n>() macros and converts all the eBPF helper functions to use them, in a similar fashion like we do with SYSCALL_DEFINE<n>() macros that are used today. Motivation for this is to hide all the register handling and all necessary casts from the user, so that it is done automatically in the background when adding a BPF_CALL_<n>() call. This makes current helpers easier to review, eases to write future helpers, avoids getting the casting mess wrong, and allows for extending all helpers at once (f.e. build time checks, etc). It also helps detecting more easily in code reviews that unused registers are not instrumented in the code by accident, breaking compatibility with existing programs. BPF_CALL_<n>() internals are quite similar to SYSCALL_DEFINE<n>() ones with some fundamental differences, for example, for generating the actual helper function that carries all u64 regs, we need to fill unused regs, so that we always end up with 5 u64 regs as an argument. I reviewed several 0-5 generated BPF_CALL_<n>() variants of the .i results and they look all as expected. No sparse issue spotted. We let this also sit for a few days with Fengguang's kbuild test robot, and there were no issues seen. On s390, it barked on the "uses dynamic stack allocation" notice, which is an old one from bpf_perf_event_output{,_tp}() reappearing here due to the conversion to the call wrapper, just telling that the perf raw record/frag sits on stack (gcc with s390's -mwarn-dynamicstack), but that's all. Did various runtime tests and they were fine as well. All eBPF helpers are now converted to use these macros, getting rid of a good chunk of all the raw castings. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-09 03:45:31 +03:00
return ____bpf_perf_event_output(regs, map, flags, data, size);
}
static const struct bpf_func_proto bpf_perf_event_output_proto_tp = {
.func = bpf_perf_event_output_tp,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_CONST_MAP_PTR,
.arg3_type = ARG_ANYTHING,
.arg4_type = ARG_PTR_TO_MEM,
bpf: change bpf_perf_event_output arg5 type to ARG_CONST_SIZE_OR_ZERO Commit 9fd29c08e520 ("bpf: improve verifier ARG_CONST_SIZE_OR_ZERO semantics") relaxed the treatment of ARG_CONST_SIZE_OR_ZERO due to the way the compiler generates optimized BPF code when checking boundaries of an argument from C code. A typical example of this optimized code can be generated using the bpf_perf_event_output helper when operating on variable memory: /* len is a generic scalar */ if (len > 0 && len <= 0x7fff) bpf_perf_event_output(ctx, &perf_map, 0, buf, len); 110: (79) r5 = *(u64 *)(r10 -40) 111: (bf) r1 = r5 112: (07) r1 += -1 113: (25) if r1 > 0x7ffe goto pc+6 114: (bf) r1 = r6 115: (18) r2 = 0xffff94e5f166c200 117: (b7) r3 = 0 118: (bf) r4 = r7 119: (85) call bpf_perf_event_output#25 R5 min value is negative, either use unsigned or 'var &= const' With this code, the verifier loses track of the variable. Replacing arg5 with ARG_CONST_SIZE_OR_ZERO is thus desirable since it avoids this quite common case which leads to usability issues, and the compiler generates code that the verifier can more easily test: if (len <= 0x7fff) bpf_perf_event_output(ctx, &perf_map, 0, buf, len); or bpf_perf_event_output(ctx, &perf_map, 0, buf, len & 0x7fff); No changes to the bpf_perf_event_output helper are necessary since it can handle a case where size is 0, and an empty frame is pushed. Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Gianluca Borello <g.borello@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2017-11-22 21:32:56 +03:00
.arg5_type = ARG_CONST_SIZE_OR_ZERO,
};
bpf: add BPF_CALL_x macros for declaring helpers This work adds BPF_CALL_<n>() macros and converts all the eBPF helper functions to use them, in a similar fashion like we do with SYSCALL_DEFINE<n>() macros that are used today. Motivation for this is to hide all the register handling and all necessary casts from the user, so that it is done automatically in the background when adding a BPF_CALL_<n>() call. This makes current helpers easier to review, eases to write future helpers, avoids getting the casting mess wrong, and allows for extending all helpers at once (f.e. build time checks, etc). It also helps detecting more easily in code reviews that unused registers are not instrumented in the code by accident, breaking compatibility with existing programs. BPF_CALL_<n>() internals are quite similar to SYSCALL_DEFINE<n>() ones with some fundamental differences, for example, for generating the actual helper function that carries all u64 regs, we need to fill unused regs, so that we always end up with 5 u64 regs as an argument. I reviewed several 0-5 generated BPF_CALL_<n>() variants of the .i results and they look all as expected. No sparse issue spotted. We let this also sit for a few days with Fengguang's kbuild test robot, and there were no issues seen. On s390, it barked on the "uses dynamic stack allocation" notice, which is an old one from bpf_perf_event_output{,_tp}() reappearing here due to the conversion to the call wrapper, just telling that the perf raw record/frag sits on stack (gcc with s390's -mwarn-dynamicstack), but that's all. Did various runtime tests and they were fine as well. All eBPF helpers are now converted to use these macros, getting rid of a good chunk of all the raw castings. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-09 03:45:31 +03:00
BPF_CALL_3(bpf_get_stackid_tp, void *, tp_buff, struct bpf_map *, map,
u64, flags)
{
bpf: add BPF_CALL_x macros for declaring helpers This work adds BPF_CALL_<n>() macros and converts all the eBPF helper functions to use them, in a similar fashion like we do with SYSCALL_DEFINE<n>() macros that are used today. Motivation for this is to hide all the register handling and all necessary casts from the user, so that it is done automatically in the background when adding a BPF_CALL_<n>() call. This makes current helpers easier to review, eases to write future helpers, avoids getting the casting mess wrong, and allows for extending all helpers at once (f.e. build time checks, etc). It also helps detecting more easily in code reviews that unused registers are not instrumented in the code by accident, breaking compatibility with existing programs. BPF_CALL_<n>() internals are quite similar to SYSCALL_DEFINE<n>() ones with some fundamental differences, for example, for generating the actual helper function that carries all u64 regs, we need to fill unused regs, so that we always end up with 5 u64 regs as an argument. I reviewed several 0-5 generated BPF_CALL_<n>() variants of the .i results and they look all as expected. No sparse issue spotted. We let this also sit for a few days with Fengguang's kbuild test robot, and there were no issues seen. On s390, it barked on the "uses dynamic stack allocation" notice, which is an old one from bpf_perf_event_output{,_tp}() reappearing here due to the conversion to the call wrapper, just telling that the perf raw record/frag sits on stack (gcc with s390's -mwarn-dynamicstack), but that's all. Did various runtime tests and they were fine as well. All eBPF helpers are now converted to use these macros, getting rid of a good chunk of all the raw castings. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-09 03:45:31 +03:00
struct pt_regs *regs = *(struct pt_regs **)tp_buff;
bpf: add BPF_CALL_x macros for declaring helpers This work adds BPF_CALL_<n>() macros and converts all the eBPF helper functions to use them, in a similar fashion like we do with SYSCALL_DEFINE<n>() macros that are used today. Motivation for this is to hide all the register handling and all necessary casts from the user, so that it is done automatically in the background when adding a BPF_CALL_<n>() call. This makes current helpers easier to review, eases to write future helpers, avoids getting the casting mess wrong, and allows for extending all helpers at once (f.e. build time checks, etc). It also helps detecting more easily in code reviews that unused registers are not instrumented in the code by accident, breaking compatibility with existing programs. BPF_CALL_<n>() internals are quite similar to SYSCALL_DEFINE<n>() ones with some fundamental differences, for example, for generating the actual helper function that carries all u64 regs, we need to fill unused regs, so that we always end up with 5 u64 regs as an argument. I reviewed several 0-5 generated BPF_CALL_<n>() variants of the .i results and they look all as expected. No sparse issue spotted. We let this also sit for a few days with Fengguang's kbuild test robot, and there were no issues seen. On s390, it barked on the "uses dynamic stack allocation" notice, which is an old one from bpf_perf_event_output{,_tp}() reappearing here due to the conversion to the call wrapper, just telling that the perf raw record/frag sits on stack (gcc with s390's -mwarn-dynamicstack), but that's all. Did various runtime tests and they were fine as well. All eBPF helpers are now converted to use these macros, getting rid of a good chunk of all the raw castings. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-09 03:45:31 +03:00
/*
* Same comment as in bpf_perf_event_output_tp(), only that this time
* the other helper's function body cannot be inlined due to being
* external, thus we need to call raw helper function.
*/
return bpf_get_stackid((unsigned long) regs, (unsigned long) map,
flags, 0, 0);
}
static const struct bpf_func_proto bpf_get_stackid_proto_tp = {
.func = bpf_get_stackid_tp,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_CONST_MAP_PTR,
.arg3_type = ARG_ANYTHING,
};
BPF_CALL_4(bpf_get_stack_tp, void *, tp_buff, void *, buf, u32, size,
u64, flags)
{
struct pt_regs *regs = *(struct pt_regs **)tp_buff;
return bpf_get_stack((unsigned long) regs, (unsigned long) buf,
(unsigned long) size, flags, 0);
}
static const struct bpf_func_proto bpf_get_stack_proto_tp = {
.func = bpf_get_stack_tp,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_PTR_TO_UNINIT_MEM,
.arg3_type = ARG_CONST_SIZE_OR_ZERO,
.arg4_type = ARG_ANYTHING,
};
bpf: Check attach type at prog load time == The problem == There are use-cases when a program of some type can be attached to multiple attach points and those attach points must have different permissions to access context or to call helpers. E.g. context structure may have fields for both IPv4 and IPv6 but it doesn't make sense to read from / write to IPv6 field when attach point is somewhere in IPv4 stack. Same applies to BPF-helpers: it may make sense to call some helper from some attach point, but not from other for same prog type. == The solution == Introduce `expected_attach_type` field in in `struct bpf_attr` for `BPF_PROG_LOAD` command. If scenario described in "The problem" section is the case for some prog type, the field will be checked twice: 1) At load time prog type is checked to see if attach type for it must be known to validate program permissions correctly. Prog will be rejected with EINVAL if it's the case and `expected_attach_type` is not specified or has invalid value. 2) At attach time `attach_type` is compared with `expected_attach_type`, if prog type requires to have one, and, if they differ, attach will be rejected with EINVAL. The `expected_attach_type` is now available as part of `struct bpf_prog` in both `bpf_verifier_ops->is_valid_access()` and `bpf_verifier_ops->get_func_proto()` () and can be used to check context accesses and calls to helpers correspondingly. Initially the idea was discussed by Alexei Starovoitov <ast@fb.com> and Daniel Borkmann <daniel@iogearbox.net> here: https://marc.info/?l=linux-netdev&m=152107378717201&w=2 Signed-off-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-31 01:08:00 +03:00
static const struct bpf_func_proto *
tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
switch (func_id) {
case BPF_FUNC_perf_event_output:
return &bpf_perf_event_output_proto_tp;
case BPF_FUNC_get_stackid:
return &bpf_get_stackid_proto_tp;
case BPF_FUNC_get_stack:
return &bpf_get_stack_proto_tp;
default:
return bpf_tracing_func_proto(func_id, prog);
}
}
static bool tp_prog_is_valid_access(int off, int size, enum bpf_access_type type,
bpf: Check attach type at prog load time == The problem == There are use-cases when a program of some type can be attached to multiple attach points and those attach points must have different permissions to access context or to call helpers. E.g. context structure may have fields for both IPv4 and IPv6 but it doesn't make sense to read from / write to IPv6 field when attach point is somewhere in IPv4 stack. Same applies to BPF-helpers: it may make sense to call some helper from some attach point, but not from other for same prog type. == The solution == Introduce `expected_attach_type` field in in `struct bpf_attr` for `BPF_PROG_LOAD` command. If scenario described in "The problem" section is the case for some prog type, the field will be checked twice: 1) At load time prog type is checked to see if attach type for it must be known to validate program permissions correctly. Prog will be rejected with EINVAL if it's the case and `expected_attach_type` is not specified or has invalid value. 2) At attach time `attach_type` is compared with `expected_attach_type`, if prog type requires to have one, and, if they differ, attach will be rejected with EINVAL. The `expected_attach_type` is now available as part of `struct bpf_prog` in both `bpf_verifier_ops->is_valid_access()` and `bpf_verifier_ops->get_func_proto()` () and can be used to check context accesses and calls to helpers correspondingly. Initially the idea was discussed by Alexei Starovoitov <ast@fb.com> and Daniel Borkmann <daniel@iogearbox.net> here: https://marc.info/?l=linux-netdev&m=152107378717201&w=2 Signed-off-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-31 01:08:00 +03:00
const struct bpf_prog *prog,
struct bpf_insn_access_aux *info)
{
if (off < sizeof(void *) || off >= PERF_MAX_TRACE_SIZE)
return false;
if (type != BPF_READ)
return false;
if (off % size != 0)
return false;
BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(__u64));
return true;
}
const struct bpf_verifier_ops tracepoint_verifier_ops = {
.get_func_proto = tp_prog_func_proto,
.is_valid_access = tp_prog_is_valid_access,
};
const struct bpf_prog_ops tracepoint_prog_ops = {
};
BPF_CALL_3(bpf_perf_prog_read_value, struct bpf_perf_event_data_kern *, ctx,
struct bpf_perf_event_value *, buf, u32, size)
{
int err = -EINVAL;
if (unlikely(size != sizeof(struct bpf_perf_event_value)))
goto clear;
err = perf_event_read_local(ctx->event, &buf->counter, &buf->enabled,
&buf->running);
if (unlikely(err))
goto clear;
return 0;
clear:
memset(buf, 0, size);
return err;
}
static const struct bpf_func_proto bpf_perf_prog_read_value_proto = {
.func = bpf_perf_prog_read_value,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_PTR_TO_UNINIT_MEM,
.arg3_type = ARG_CONST_SIZE,
};
BPF_CALL_4(bpf_read_branch_records, struct bpf_perf_event_data_kern *, ctx,
void *, buf, u32, size, u64, flags)
{
#ifndef CONFIG_X86
return -ENOENT;
#else
static const u32 br_entry_size = sizeof(struct perf_branch_entry);
struct perf_branch_stack *br_stack = ctx->data->br_stack;
u32 to_copy;
if (unlikely(flags & ~BPF_F_GET_BRANCH_RECORDS_SIZE))
return -EINVAL;
if (unlikely(!br_stack))
return -EINVAL;
if (flags & BPF_F_GET_BRANCH_RECORDS_SIZE)
return br_stack->nr * br_entry_size;
if (!buf || (size % br_entry_size != 0))
return -EINVAL;
to_copy = min_t(u32, br_stack->nr * br_entry_size, size);
memcpy(buf, br_stack->entries, to_copy);
return to_copy;
#endif
}
static const struct bpf_func_proto bpf_read_branch_records_proto = {
.func = bpf_read_branch_records,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_PTR_TO_MEM_OR_NULL,
.arg3_type = ARG_CONST_SIZE_OR_ZERO,
.arg4_type = ARG_ANYTHING,
};
bpf: Check attach type at prog load time == The problem == There are use-cases when a program of some type can be attached to multiple attach points and those attach points must have different permissions to access context or to call helpers. E.g. context structure may have fields for both IPv4 and IPv6 but it doesn't make sense to read from / write to IPv6 field when attach point is somewhere in IPv4 stack. Same applies to BPF-helpers: it may make sense to call some helper from some attach point, but not from other for same prog type. == The solution == Introduce `expected_attach_type` field in in `struct bpf_attr` for `BPF_PROG_LOAD` command. If scenario described in "The problem" section is the case for some prog type, the field will be checked twice: 1) At load time prog type is checked to see if attach type for it must be known to validate program permissions correctly. Prog will be rejected with EINVAL if it's the case and `expected_attach_type` is not specified or has invalid value. 2) At attach time `attach_type` is compared with `expected_attach_type`, if prog type requires to have one, and, if they differ, attach will be rejected with EINVAL. The `expected_attach_type` is now available as part of `struct bpf_prog` in both `bpf_verifier_ops->is_valid_access()` and `bpf_verifier_ops->get_func_proto()` () and can be used to check context accesses and calls to helpers correspondingly. Initially the idea was discussed by Alexei Starovoitov <ast@fb.com> and Daniel Borkmann <daniel@iogearbox.net> here: https://marc.info/?l=linux-netdev&m=152107378717201&w=2 Signed-off-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-31 01:08:00 +03:00
static const struct bpf_func_proto *
pe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
switch (func_id) {
case BPF_FUNC_perf_event_output:
return &bpf_perf_event_output_proto_tp;
case BPF_FUNC_get_stackid:
return &bpf_get_stackid_proto_pe;
case BPF_FUNC_get_stack:
return &bpf_get_stack_proto_pe;
case BPF_FUNC_perf_prog_read_value:
return &bpf_perf_prog_read_value_proto;
case BPF_FUNC_read_branch_records:
return &bpf_read_branch_records_proto;
default:
return bpf_tracing_func_proto(func_id, prog);
}
}
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
/*
* bpf_raw_tp_regs are separate from bpf_pt_regs used from skb/xdp
* to avoid potential recursive reuse issue when/if tracepoints are added
* inside bpf_*_event_output, bpf_get_stackid and/or bpf_get_stack.
*
* Since raw tracepoints run despite bpf_prog_active, support concurrent usage
* in normal, irq, and nmi context.
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
*/
struct bpf_raw_tp_regs {
struct pt_regs regs[3];
};
static DEFINE_PER_CPU(struct bpf_raw_tp_regs, bpf_raw_tp_regs);
static DEFINE_PER_CPU(int, bpf_raw_tp_nest_level);
static struct pt_regs *get_bpf_raw_tp_regs(void)
{
struct bpf_raw_tp_regs *tp_regs = this_cpu_ptr(&bpf_raw_tp_regs);
int nest_level = this_cpu_inc_return(bpf_raw_tp_nest_level);
if (WARN_ON_ONCE(nest_level > ARRAY_SIZE(tp_regs->regs))) {
this_cpu_dec(bpf_raw_tp_nest_level);
return ERR_PTR(-EBUSY);
}
return &tp_regs->regs[nest_level - 1];
}
static void put_bpf_raw_tp_regs(void)
{
this_cpu_dec(bpf_raw_tp_nest_level);
}
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
BPF_CALL_5(bpf_perf_event_output_raw_tp, struct bpf_raw_tracepoint_args *, args,
struct bpf_map *, map, u64, flags, void *, data, u64, size)
{
struct pt_regs *regs = get_bpf_raw_tp_regs();
int ret;
if (IS_ERR(regs))
return PTR_ERR(regs);
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
perf_fetch_caller_regs(regs);
ret = ____bpf_perf_event_output(regs, map, flags, data, size);
put_bpf_raw_tp_regs();
return ret;
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
}
static const struct bpf_func_proto bpf_perf_event_output_proto_raw_tp = {
.func = bpf_perf_event_output_raw_tp,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_CONST_MAP_PTR,
.arg3_type = ARG_ANYTHING,
.arg4_type = ARG_PTR_TO_MEM,
.arg5_type = ARG_CONST_SIZE_OR_ZERO,
};
extern const struct bpf_func_proto bpf_skb_output_proto;
extern const struct bpf_func_proto bpf_xdp_output_proto;
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
BPF_CALL_3(bpf_get_stackid_raw_tp, struct bpf_raw_tracepoint_args *, args,
struct bpf_map *, map, u64, flags)
{
struct pt_regs *regs = get_bpf_raw_tp_regs();
int ret;
if (IS_ERR(regs))
return PTR_ERR(regs);
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
perf_fetch_caller_regs(regs);
/* similar to bpf_perf_event_output_tp, but pt_regs fetched differently */
ret = bpf_get_stackid((unsigned long) regs, (unsigned long) map,
flags, 0, 0);
put_bpf_raw_tp_regs();
return ret;
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
}
static const struct bpf_func_proto bpf_get_stackid_proto_raw_tp = {
.func = bpf_get_stackid_raw_tp,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_CONST_MAP_PTR,
.arg3_type = ARG_ANYTHING,
};
BPF_CALL_4(bpf_get_stack_raw_tp, struct bpf_raw_tracepoint_args *, args,
void *, buf, u32, size, u64, flags)
{
struct pt_regs *regs = get_bpf_raw_tp_regs();
int ret;
if (IS_ERR(regs))
return PTR_ERR(regs);
perf_fetch_caller_regs(regs);
ret = bpf_get_stack((unsigned long) regs, (unsigned long) buf,
(unsigned long) size, flags, 0);
put_bpf_raw_tp_regs();
return ret;
}
static const struct bpf_func_proto bpf_get_stack_proto_raw_tp = {
.func = bpf_get_stack_raw_tp,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_PTR_TO_MEM,
.arg3_type = ARG_CONST_SIZE_OR_ZERO,
.arg4_type = ARG_ANYTHING,
};
bpf: Check attach type at prog load time == The problem == There are use-cases when a program of some type can be attached to multiple attach points and those attach points must have different permissions to access context or to call helpers. E.g. context structure may have fields for both IPv4 and IPv6 but it doesn't make sense to read from / write to IPv6 field when attach point is somewhere in IPv4 stack. Same applies to BPF-helpers: it may make sense to call some helper from some attach point, but not from other for same prog type. == The solution == Introduce `expected_attach_type` field in in `struct bpf_attr` for `BPF_PROG_LOAD` command. If scenario described in "The problem" section is the case for some prog type, the field will be checked twice: 1) At load time prog type is checked to see if attach type for it must be known to validate program permissions correctly. Prog will be rejected with EINVAL if it's the case and `expected_attach_type` is not specified or has invalid value. 2) At attach time `attach_type` is compared with `expected_attach_type`, if prog type requires to have one, and, if they differ, attach will be rejected with EINVAL. The `expected_attach_type` is now available as part of `struct bpf_prog` in both `bpf_verifier_ops->is_valid_access()` and `bpf_verifier_ops->get_func_proto()` () and can be used to check context accesses and calls to helpers correspondingly. Initially the idea was discussed by Alexei Starovoitov <ast@fb.com> and Daniel Borkmann <daniel@iogearbox.net> here: https://marc.info/?l=linux-netdev&m=152107378717201&w=2 Signed-off-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-31 01:08:00 +03:00
static const struct bpf_func_proto *
raw_tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
{
switch (func_id) {
case BPF_FUNC_perf_event_output:
return &bpf_perf_event_output_proto_raw_tp;
case BPF_FUNC_get_stackid:
return &bpf_get_stackid_proto_raw_tp;
case BPF_FUNC_get_stack:
return &bpf_get_stack_proto_raw_tp;
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
default:
return bpf_tracing_func_proto(func_id, prog);
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
}
}
const struct bpf_func_proto *
tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
switch (func_id) {
#ifdef CONFIG_NET
case BPF_FUNC_skb_output:
return &bpf_skb_output_proto;
case BPF_FUNC_xdp_output:
return &bpf_xdp_output_proto;
case BPF_FUNC_skc_to_tcp6_sock:
return &bpf_skc_to_tcp6_sock_proto;
case BPF_FUNC_skc_to_tcp_sock:
return &bpf_skc_to_tcp_sock_proto;
case BPF_FUNC_skc_to_tcp_timewait_sock:
return &bpf_skc_to_tcp_timewait_sock_proto;
case BPF_FUNC_skc_to_tcp_request_sock:
return &bpf_skc_to_tcp_request_sock_proto;
case BPF_FUNC_skc_to_udp6_sock:
return &bpf_skc_to_udp6_sock_proto;
#endif
bpf: Add bpf_seq_printf and bpf_seq_write helpers Two helpers bpf_seq_printf and bpf_seq_write, are added for writing data to the seq_file buffer. bpf_seq_printf supports common format string flag/width/type fields so at least I can get identical results for netlink and ipv6_route targets. For bpf_seq_printf and bpf_seq_write, return value -EOVERFLOW specifically indicates a write failure due to overflow, which means the object will be repeated in the next bpf invocation if object collection stays the same. Note that if the object collection is changed, depending how collection traversal is done, even if the object still in the collection, it may not be visited. For bpf_seq_printf, format %s, %p{i,I}{4,6} needs to read kernel memory. Reading kernel memory may fail in the following two cases: - invalid kernel address, or - valid kernel address but requiring a major fault If reading kernel memory failed, the %s string will be an empty string and %p{i,I}{4,6} will be all 0. Not returning error to bpf program is consistent with what bpf_trace_printk() does for now. bpf_seq_printf may return -EBUSY meaning that internal percpu buffer for memory copy of strings or other pointees is not available. Bpf program can return 1 to indicate it wants the same object to be repeated. Right now, this should not happen on no-RT kernels since migrate_disable(), which guards bpf prog call, calls preempt_disable(). Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200509175914.2476661-1-yhs@fb.com
2020-05-09 20:59:14 +03:00
case BPF_FUNC_seq_printf:
return prog->expected_attach_type == BPF_TRACE_ITER ?
&bpf_seq_printf_proto :
NULL;
case BPF_FUNC_seq_write:
return prog->expected_attach_type == BPF_TRACE_ITER ?
&bpf_seq_write_proto :
NULL;
case BPF_FUNC_seq_printf_btf:
return prog->expected_attach_type == BPF_TRACE_ITER ?
&bpf_seq_printf_btf_proto :
NULL;
case BPF_FUNC_d_path:
return &bpf_d_path_proto;
default:
return raw_tp_prog_func_proto(func_id, prog);
}
}
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
static bool raw_tp_prog_is_valid_access(int off, int size,
enum bpf_access_type type,
bpf: Check attach type at prog load time == The problem == There are use-cases when a program of some type can be attached to multiple attach points and those attach points must have different permissions to access context or to call helpers. E.g. context structure may have fields for both IPv4 and IPv6 but it doesn't make sense to read from / write to IPv6 field when attach point is somewhere in IPv4 stack. Same applies to BPF-helpers: it may make sense to call some helper from some attach point, but not from other for same prog type. == The solution == Introduce `expected_attach_type` field in in `struct bpf_attr` for `BPF_PROG_LOAD` command. If scenario described in "The problem" section is the case for some prog type, the field will be checked twice: 1) At load time prog type is checked to see if attach type for it must be known to validate program permissions correctly. Prog will be rejected with EINVAL if it's the case and `expected_attach_type` is not specified or has invalid value. 2) At attach time `attach_type` is compared with `expected_attach_type`, if prog type requires to have one, and, if they differ, attach will be rejected with EINVAL. The `expected_attach_type` is now available as part of `struct bpf_prog` in both `bpf_verifier_ops->is_valid_access()` and `bpf_verifier_ops->get_func_proto()` () and can be used to check context accesses and calls to helpers correspondingly. Initially the idea was discussed by Alexei Starovoitov <ast@fb.com> and Daniel Borkmann <daniel@iogearbox.net> here: https://marc.info/?l=linux-netdev&m=152107378717201&w=2 Signed-off-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-31 01:08:00 +03:00
const struct bpf_prog *prog,
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
struct bpf_insn_access_aux *info)
{
if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS)
return false;
if (type != BPF_READ)
return false;
if (off % size != 0)
return false;
return true;
}
static bool tracing_prog_is_valid_access(int off, int size,
enum bpf_access_type type,
const struct bpf_prog *prog,
struct bpf_insn_access_aux *info)
{
if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS)
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
return false;
if (type != BPF_READ)
return false;
if (off % size != 0)
return false;
bpf: Implement accurate raw_tp context access via BTF libbpf analyzes bpf C program, searches in-kernel BTF for given type name and stores it into expected_attach_type. The kernel verifier expects this btf_id to point to something like: typedef void (*btf_trace_kfree_skb)(void *, struct sk_buff *skb, void *loc); which represents signature of raw_tracepoint "kfree_skb". Then btf_ctx_access() matches ctx+0 access in bpf program with 'skb' and 'ctx+8' access with 'loc' arguments of "kfree_skb" tracepoint. In first case it passes btf_id of 'struct sk_buff *' back to the verifier core and 'void *' in second case. Then the verifier tracks PTR_TO_BTF_ID as any other pointer type. Like PTR_TO_SOCKET points to 'struct bpf_sock', PTR_TO_TCP_SOCK points to 'struct bpf_tcp_sock', and so on. PTR_TO_BTF_ID points to in-kernel structs. If 1234 is btf_id of 'struct sk_buff' in vmlinux's BTF then PTR_TO_BTF_ID#1234 points to one of in kernel skbs. When PTR_TO_BTF_ID#1234 is dereferenced (like r2 = *(u64 *)r1 + 32) the btf_struct_access() checks which field of 'struct sk_buff' is at offset 32. Checks that size of access matches type definition of the field and continues to track the dereferenced type. If that field was a pointer to 'struct net_device' the r2's type will be PTR_TO_BTF_ID#456. Where 456 is btf_id of 'struct net_device' in vmlinux's BTF. Such verifier analysis prevents "cheating" in BPF C program. The program cannot cast arbitrary pointer to 'struct sk_buff *' and access it. C compiler would allow type cast, of course, but the verifier will notice type mismatch based on BPF assembly and in-kernel BTF. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20191016032505.2089704-7-ast@kernel.org
2019-10-16 06:25:00 +03:00
return btf_ctx_access(off, size, type, prog, info);
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
}
int __weak bpf_prog_test_run_tracing(struct bpf_prog *prog,
const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
return -ENOTSUPP;
}
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
const struct bpf_verifier_ops raw_tracepoint_verifier_ops = {
.get_func_proto = raw_tp_prog_func_proto,
.is_valid_access = raw_tp_prog_is_valid_access,
};
const struct bpf_prog_ops raw_tracepoint_prog_ops = {
#ifdef CONFIG_NET
.test_run = bpf_prog_test_run_raw_tp,
#endif
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
};
const struct bpf_verifier_ops tracing_verifier_ops = {
.get_func_proto = tracing_prog_func_proto,
.is_valid_access = tracing_prog_is_valid_access,
};
const struct bpf_prog_ops tracing_prog_ops = {
.test_run = bpf_prog_test_run_tracing,
};
static bool raw_tp_writable_prog_is_valid_access(int off, int size,
enum bpf_access_type type,
const struct bpf_prog *prog,
struct bpf_insn_access_aux *info)
{
if (off == 0) {
if (size != sizeof(u64) || type != BPF_READ)
return false;
info->reg_type = PTR_TO_TP_BUFFER;
}
return raw_tp_prog_is_valid_access(off, size, type, prog, info);
}
const struct bpf_verifier_ops raw_tracepoint_writable_verifier_ops = {
.get_func_proto = raw_tp_prog_func_proto,
.is_valid_access = raw_tp_writable_prog_is_valid_access,
};
const struct bpf_prog_ops raw_tracepoint_writable_prog_ops = {
};
static bool pe_prog_is_valid_access(int off, int size, enum bpf_access_type type,
bpf: Check attach type at prog load time == The problem == There are use-cases when a program of some type can be attached to multiple attach points and those attach points must have different permissions to access context or to call helpers. E.g. context structure may have fields for both IPv4 and IPv6 but it doesn't make sense to read from / write to IPv6 field when attach point is somewhere in IPv4 stack. Same applies to BPF-helpers: it may make sense to call some helper from some attach point, but not from other for same prog type. == The solution == Introduce `expected_attach_type` field in in `struct bpf_attr` for `BPF_PROG_LOAD` command. If scenario described in "The problem" section is the case for some prog type, the field will be checked twice: 1) At load time prog type is checked to see if attach type for it must be known to validate program permissions correctly. Prog will be rejected with EINVAL if it's the case and `expected_attach_type` is not specified or has invalid value. 2) At attach time `attach_type` is compared with `expected_attach_type`, if prog type requires to have one, and, if they differ, attach will be rejected with EINVAL. The `expected_attach_type` is now available as part of `struct bpf_prog` in both `bpf_verifier_ops->is_valid_access()` and `bpf_verifier_ops->get_func_proto()` () and can be used to check context accesses and calls to helpers correspondingly. Initially the idea was discussed by Alexei Starovoitov <ast@fb.com> and Daniel Borkmann <daniel@iogearbox.net> here: https://marc.info/?l=linux-netdev&m=152107378717201&w=2 Signed-off-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-31 01:08:00 +03:00
const struct bpf_prog *prog,
struct bpf_insn_access_aux *info)
{
const int size_u64 = sizeof(u64);
if (off < 0 || off >= sizeof(struct bpf_perf_event_data))
return false;
if (type != BPF_READ)
return false;
bpf: fix context access in tracing progs on 32 bit archs Wang reported that all the testcases for BPF_PROG_TYPE_PERF_EVENT program type in test_verifier report the following errors on x86_32: 172/p unpriv: spill/fill of different pointers ldx FAIL Unexpected error message! 0: (bf) r6 = r10 1: (07) r6 += -8 2: (15) if r1 == 0x0 goto pc+3 R1=ctx(id=0,off=0,imm=0) R6=fp-8,call_-1 R10=fp0,call_-1 3: (bf) r2 = r10 4: (07) r2 += -76 5: (7b) *(u64 *)(r6 +0) = r2 6: (55) if r1 != 0x0 goto pc+1 R1=ctx(id=0,off=0,imm=0) R2=fp-76,call_-1 R6=fp-8,call_-1 R10=fp0,call_-1 fp-8=fp 7: (7b) *(u64 *)(r6 +0) = r1 8: (79) r1 = *(u64 *)(r6 +0) 9: (79) r1 = *(u64 *)(r1 +68) invalid bpf_context access off=68 size=8 378/p check bpf_perf_event_data->sample_period byte load permitted FAIL Failed to load prog 'Permission denied'! 0: (b7) r0 = 0 1: (71) r0 = *(u8 *)(r1 +68) invalid bpf_context access off=68 size=1 379/p check bpf_perf_event_data->sample_period half load permitted FAIL Failed to load prog 'Permission denied'! 0: (b7) r0 = 0 1: (69) r0 = *(u16 *)(r1 +68) invalid bpf_context access off=68 size=2 380/p check bpf_perf_event_data->sample_period word load permitted FAIL Failed to load prog 'Permission denied'! 0: (b7) r0 = 0 1: (61) r0 = *(u32 *)(r1 +68) invalid bpf_context access off=68 size=4 381/p check bpf_perf_event_data->sample_period dword load permitted FAIL Failed to load prog 'Permission denied'! 0: (b7) r0 = 0 1: (79) r0 = *(u64 *)(r1 +68) invalid bpf_context access off=68 size=8 Reason is that struct pt_regs on x86_32 doesn't fully align to 8 byte boundary due to its size of 68 bytes. Therefore, bpf_ctx_narrow_access_ok() will then bail out saying that off & (size_default - 1) which is 68 & 7 doesn't cleanly align in the case of sample_period access from struct bpf_perf_event_data, hence verifier wrongly thinks we might be doing an unaligned access here though underlying arch can handle it just fine. Therefore adjust this down to machine size and check and rewrite the offset for narrow access on that basis. We also need to fix corresponding pe_prog_is_valid_access(), since we hit the check for off % size != 0 (e.g. 68 % 8 -> 4) in the first and last test. With that in place, progs for tracing work on x86_32. Reported-by: Wang YanQing <udknight@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Tested-by: Wang YanQing <udknight@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2018-06-03 00:06:39 +03:00
if (off % size != 0) {
if (sizeof(unsigned long) != 4)
return false;
if (size != 8)
return false;
if (off % size != 4)
return false;
}
bpf: simplify narrower ctx access This work tries to make the semantics and code around the narrower ctx access a bit easier to follow. Right now everything is done inside the .is_valid_access(). Offset matching is done differently for read/write types, meaning writes don't support narrower access and thus matching only on offsetof(struct foo, bar) is enough whereas for read case that supports narrower access we must check for offsetof(struct foo, bar) + offsetof(struct foo, bar) + sizeof(<bar>) - 1 for each of the cases. For read cases of individual members that don't support narrower access (like packet pointers or skb->cb[] case which has its own narrow access logic), we check as usual only offsetof(struct foo, bar) like in write case. Then, for the case where narrower access is allowed, we also need to set the aux info for the access. Meaning, ctx_field_size and converted_op_size have to be set. First is the original field size e.g. sizeof(<bar>) as in above example from the user facing ctx, and latter one is the target size after actual rewrite happened, thus for the kernel facing ctx. Also here we need the range match and we need to keep track changing convert_ctx_access() and converted_op_size from is_valid_access() as both are not at the same location. We can simplify the code a bit: check_ctx_access() becomes simpler in that we only store ctx_field_size as a meta data and later in convert_ctx_accesses() we fetch the target_size right from the location where we do convert. Should the verifier be misconfigured we do reject for BPF_WRITE cases or target_size that are not provided. For the subsystems, we always work on ranges in is_valid_access() and add small helpers for ranges and narrow access, convert_ctx_accesses() sets target_size for the relevant instruction. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: John Fastabend <john.fastabend@gmail.com> Cc: Yonghong Song <yhs@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-02 03:13:27 +03:00
switch (off) {
case bpf_ctx_range(struct bpf_perf_event_data, sample_period):
bpf_ctx_record_field_size(info, size_u64);
if (!bpf_ctx_narrow_access_ok(off, size, size_u64))
return false;
break;
case bpf_ctx_range(struct bpf_perf_event_data, addr):
bpf_ctx_record_field_size(info, size_u64);
if (!bpf_ctx_narrow_access_ok(off, size, size_u64))
return false;
bpf: simplify narrower ctx access This work tries to make the semantics and code around the narrower ctx access a bit easier to follow. Right now everything is done inside the .is_valid_access(). Offset matching is done differently for read/write types, meaning writes don't support narrower access and thus matching only on offsetof(struct foo, bar) is enough whereas for read case that supports narrower access we must check for offsetof(struct foo, bar) + offsetof(struct foo, bar) + sizeof(<bar>) - 1 for each of the cases. For read cases of individual members that don't support narrower access (like packet pointers or skb->cb[] case which has its own narrow access logic), we check as usual only offsetof(struct foo, bar) like in write case. Then, for the case where narrower access is allowed, we also need to set the aux info for the access. Meaning, ctx_field_size and converted_op_size have to be set. First is the original field size e.g. sizeof(<bar>) as in above example from the user facing ctx, and latter one is the target size after actual rewrite happened, thus for the kernel facing ctx. Also here we need the range match and we need to keep track changing convert_ctx_access() and converted_op_size from is_valid_access() as both are not at the same location. We can simplify the code a bit: check_ctx_access() becomes simpler in that we only store ctx_field_size as a meta data and later in convert_ctx_accesses() we fetch the target_size right from the location where we do convert. Should the verifier be misconfigured we do reject for BPF_WRITE cases or target_size that are not provided. For the subsystems, we always work on ranges in is_valid_access() and add small helpers for ranges and narrow access, convert_ctx_accesses() sets target_size for the relevant instruction. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: John Fastabend <john.fastabend@gmail.com> Cc: Yonghong Song <yhs@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-02 03:13:27 +03:00
break;
default:
if (size != sizeof(long))
return false;
}
bpf: simplify narrower ctx access This work tries to make the semantics and code around the narrower ctx access a bit easier to follow. Right now everything is done inside the .is_valid_access(). Offset matching is done differently for read/write types, meaning writes don't support narrower access and thus matching only on offsetof(struct foo, bar) is enough whereas for read case that supports narrower access we must check for offsetof(struct foo, bar) + offsetof(struct foo, bar) + sizeof(<bar>) - 1 for each of the cases. For read cases of individual members that don't support narrower access (like packet pointers or skb->cb[] case which has its own narrow access logic), we check as usual only offsetof(struct foo, bar) like in write case. Then, for the case where narrower access is allowed, we also need to set the aux info for the access. Meaning, ctx_field_size and converted_op_size have to be set. First is the original field size e.g. sizeof(<bar>) as in above example from the user facing ctx, and latter one is the target size after actual rewrite happened, thus for the kernel facing ctx. Also here we need the range match and we need to keep track changing convert_ctx_access() and converted_op_size from is_valid_access() as both are not at the same location. We can simplify the code a bit: check_ctx_access() becomes simpler in that we only store ctx_field_size as a meta data and later in convert_ctx_accesses() we fetch the target_size right from the location where we do convert. Should the verifier be misconfigured we do reject for BPF_WRITE cases or target_size that are not provided. For the subsystems, we always work on ranges in is_valid_access() and add small helpers for ranges and narrow access, convert_ctx_accesses() sets target_size for the relevant instruction. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: John Fastabend <john.fastabend@gmail.com> Cc: Yonghong Song <yhs@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-02 03:13:27 +03:00
return true;
}
static u32 pe_prog_convert_ctx_access(enum bpf_access_type type,
const struct bpf_insn *si,
struct bpf_insn *insn_buf,
bpf: simplify narrower ctx access This work tries to make the semantics and code around the narrower ctx access a bit easier to follow. Right now everything is done inside the .is_valid_access(). Offset matching is done differently for read/write types, meaning writes don't support narrower access and thus matching only on offsetof(struct foo, bar) is enough whereas for read case that supports narrower access we must check for offsetof(struct foo, bar) + offsetof(struct foo, bar) + sizeof(<bar>) - 1 for each of the cases. For read cases of individual members that don't support narrower access (like packet pointers or skb->cb[] case which has its own narrow access logic), we check as usual only offsetof(struct foo, bar) like in write case. Then, for the case where narrower access is allowed, we also need to set the aux info for the access. Meaning, ctx_field_size and converted_op_size have to be set. First is the original field size e.g. sizeof(<bar>) as in above example from the user facing ctx, and latter one is the target size after actual rewrite happened, thus for the kernel facing ctx. Also here we need the range match and we need to keep track changing convert_ctx_access() and converted_op_size from is_valid_access() as both are not at the same location. We can simplify the code a bit: check_ctx_access() becomes simpler in that we only store ctx_field_size as a meta data and later in convert_ctx_accesses() we fetch the target_size right from the location where we do convert. Should the verifier be misconfigured we do reject for BPF_WRITE cases or target_size that are not provided. For the subsystems, we always work on ranges in is_valid_access() and add small helpers for ranges and narrow access, convert_ctx_accesses() sets target_size for the relevant instruction. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: John Fastabend <john.fastabend@gmail.com> Cc: Yonghong Song <yhs@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-02 03:13:27 +03:00
struct bpf_prog *prog, u32 *target_size)
{
struct bpf_insn *insn = insn_buf;
switch (si->off) {
case offsetof(struct bpf_perf_event_data, sample_period):
*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,
data), si->dst_reg, si->src_reg,
offsetof(struct bpf_perf_event_data_kern, data));
*insn++ = BPF_LDX_MEM(BPF_DW, si->dst_reg, si->dst_reg,
bpf: simplify narrower ctx access This work tries to make the semantics and code around the narrower ctx access a bit easier to follow. Right now everything is done inside the .is_valid_access(). Offset matching is done differently for read/write types, meaning writes don't support narrower access and thus matching only on offsetof(struct foo, bar) is enough whereas for read case that supports narrower access we must check for offsetof(struct foo, bar) + offsetof(struct foo, bar) + sizeof(<bar>) - 1 for each of the cases. For read cases of individual members that don't support narrower access (like packet pointers or skb->cb[] case which has its own narrow access logic), we check as usual only offsetof(struct foo, bar) like in write case. Then, for the case where narrower access is allowed, we also need to set the aux info for the access. Meaning, ctx_field_size and converted_op_size have to be set. First is the original field size e.g. sizeof(<bar>) as in above example from the user facing ctx, and latter one is the target size after actual rewrite happened, thus for the kernel facing ctx. Also here we need the range match and we need to keep track changing convert_ctx_access() and converted_op_size from is_valid_access() as both are not at the same location. We can simplify the code a bit: check_ctx_access() becomes simpler in that we only store ctx_field_size as a meta data and later in convert_ctx_accesses() we fetch the target_size right from the location where we do convert. Should the verifier be misconfigured we do reject for BPF_WRITE cases or target_size that are not provided. For the subsystems, we always work on ranges in is_valid_access() and add small helpers for ranges and narrow access, convert_ctx_accesses() sets target_size for the relevant instruction. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: John Fastabend <john.fastabend@gmail.com> Cc: Yonghong Song <yhs@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-02 03:13:27 +03:00
bpf_target_off(struct perf_sample_data, period, 8,
target_size));
break;
case offsetof(struct bpf_perf_event_data, addr):
*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,
data), si->dst_reg, si->src_reg,
offsetof(struct bpf_perf_event_data_kern, data));
*insn++ = BPF_LDX_MEM(BPF_DW, si->dst_reg, si->dst_reg,
bpf_target_off(struct perf_sample_data, addr, 8,
target_size));
break;
default:
*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,
regs), si->dst_reg, si->src_reg,
offsetof(struct bpf_perf_event_data_kern, regs));
*insn++ = BPF_LDX_MEM(BPF_SIZEOF(long), si->dst_reg, si->dst_reg,
si->off);
break;
}
return insn - insn_buf;
}
const struct bpf_verifier_ops perf_event_verifier_ops = {
.get_func_proto = pe_prog_func_proto,
.is_valid_access = pe_prog_is_valid_access,
.convert_ctx_access = pe_prog_convert_ctx_access,
};
const struct bpf_prog_ops perf_event_prog_ops = {
};
static DEFINE_MUTEX(bpf_event_mutex);
#define BPF_TRACE_MAX_PROGS 64
int perf_event_attach_bpf_prog(struct perf_event *event,
struct bpf_prog *prog)
{
struct bpf_prog_array *old_array;
struct bpf_prog_array *new_array;
int ret = -EEXIST;
/*
* Kprobe override only works if they are on the function entry,
* and only if they are on the opt-in list.
*/
if (prog->kprobe_override &&
(!trace_kprobe_on_func_entry(event->tp_event) ||
!trace_kprobe_error_injectable(event->tp_event)))
return -EINVAL;
mutex_lock(&bpf_event_mutex);
if (event->prog)
goto unlock;
old_array = bpf_event_rcu_dereference(event->tp_event->prog_array);
if (old_array &&
bpf_prog_array_length(old_array) >= BPF_TRACE_MAX_PROGS) {
ret = -E2BIG;
goto unlock;
}
ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array);
if (ret < 0)
goto unlock;
/* set the new array to event->tp_event and set event->prog */
event->prog = prog;
rcu_assign_pointer(event->tp_event->prog_array, new_array);
bpf_prog_array_free(old_array);
unlock:
mutex_unlock(&bpf_event_mutex);
return ret;
}
void perf_event_detach_bpf_prog(struct perf_event *event)
{
struct bpf_prog_array *old_array;
struct bpf_prog_array *new_array;
int ret;
mutex_lock(&bpf_event_mutex);
if (!event->prog)
goto unlock;
old_array = bpf_event_rcu_dereference(event->tp_event->prog_array);
ret = bpf_prog_array_copy(old_array, event->prog, NULL, &new_array);
if (ret == -ENOENT)
goto unlock;
if (ret < 0) {
bpf_prog_array_delete_safe(old_array, event->prog);
} else {
rcu_assign_pointer(event->tp_event->prog_array, new_array);
bpf_prog_array_free(old_array);
}
bpf_prog_put(event->prog);
event->prog = NULL;
unlock:
mutex_unlock(&bpf_event_mutex);
}
bpf/tracing: allow user space to query prog array on the same tp Commit e87c6bc3852b ("bpf: permit multiple bpf attachments for a single perf event") added support to attach multiple bpf programs to a single perf event. Although this provides flexibility, users may want to know what other bpf programs attached to the same tp interface. Besides getting visibility for the underlying bpf system, such information may also help consolidate multiple bpf programs, understand potential performance issues due to a large array, and debug (e.g., one bpf program which overwrites return code may impact subsequent program results). Commit 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") utilized the existing perf ioctl interface and added the command PERF_EVENT_IOC_SET_BPF to attach a bpf program to a tracepoint. This patch adds a new ioctl command, given a perf event fd, to query the bpf program array attached to the same perf tracepoint event. The new uapi ioctl command: PERF_EVENT_IOC_QUERY_BPF The new uapi/linux/perf_event.h structure: struct perf_event_query_bpf { __u32 ids_len; __u32 prog_cnt; __u32 ids[0]; }; User space provides buffer "ids" for kernel to copy to. When returning from the kernel, the number of available programs in the array is set in "prog_cnt". The usage: struct perf_event_query_bpf *query = malloc(sizeof(*query) + sizeof(u32) * ids_len); query.ids_len = ids_len; err = ioctl(pmu_efd, PERF_EVENT_IOC_QUERY_BPF, query); if (err == 0) { /* query.prog_cnt is the number of available progs, * number of progs in ids: (ids_len == 0) ? 0 : query.prog_cnt */ } else if (errno == ENOSPC) { /* query.ids_len number of progs copied, * query.prog_cnt is the number of available progs */ } else { /* other errors */ } Signed-off-by: Yonghong Song <yhs@fb.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2017-12-11 22:39:02 +03:00
int perf_event_query_prog_array(struct perf_event *event, void __user *info)
bpf/tracing: allow user space to query prog array on the same tp Commit e87c6bc3852b ("bpf: permit multiple bpf attachments for a single perf event") added support to attach multiple bpf programs to a single perf event. Although this provides flexibility, users may want to know what other bpf programs attached to the same tp interface. Besides getting visibility for the underlying bpf system, such information may also help consolidate multiple bpf programs, understand potential performance issues due to a large array, and debug (e.g., one bpf program which overwrites return code may impact subsequent program results). Commit 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") utilized the existing perf ioctl interface and added the command PERF_EVENT_IOC_SET_BPF to attach a bpf program to a tracepoint. This patch adds a new ioctl command, given a perf event fd, to query the bpf program array attached to the same perf tracepoint event. The new uapi ioctl command: PERF_EVENT_IOC_QUERY_BPF The new uapi/linux/perf_event.h structure: struct perf_event_query_bpf { __u32 ids_len; __u32 prog_cnt; __u32 ids[0]; }; User space provides buffer "ids" for kernel to copy to. When returning from the kernel, the number of available programs in the array is set in "prog_cnt". The usage: struct perf_event_query_bpf *query = malloc(sizeof(*query) + sizeof(u32) * ids_len); query.ids_len = ids_len; err = ioctl(pmu_efd, PERF_EVENT_IOC_QUERY_BPF, query); if (err == 0) { /* query.prog_cnt is the number of available progs, * number of progs in ids: (ids_len == 0) ? 0 : query.prog_cnt */ } else if (errno == ENOSPC) { /* query.ids_len number of progs copied, * query.prog_cnt is the number of available progs */ } else { /* other errors */ } Signed-off-by: Yonghong Song <yhs@fb.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2017-12-11 22:39:02 +03:00
{
struct perf_event_query_bpf __user *uquery = info;
struct perf_event_query_bpf query = {};
struct bpf_prog_array *progs;
bpf/tracing: fix a deadlock in perf_event_detach_bpf_prog syzbot reported a possible deadlock in perf_event_detach_bpf_prog. The error details: ====================================================== WARNING: possible circular locking dependency detected 4.16.0-rc7+ #3 Not tainted ------------------------------------------------------ syz-executor7/24531 is trying to acquire lock: (bpf_event_mutex){+.+.}, at: [<000000008a849b07>] perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854 but task is already holding lock: (&mm->mmap_sem){++++}, at: [<0000000038768f87>] vm_mmap_pgoff+0x198/0x280 mm/util.c:353 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&mm->mmap_sem){++++}: __might_fault+0x13a/0x1d0 mm/memory.c:4571 _copy_to_user+0x2c/0xc0 lib/usercopy.c:25 copy_to_user include/linux/uaccess.h:155 [inline] bpf_prog_array_copy_info+0xf2/0x1c0 kernel/bpf/core.c:1694 perf_event_query_prog_array+0x1c7/0x2c0 kernel/trace/bpf_trace.c:891 _perf_ioctl kernel/events/core.c:4750 [inline] perf_ioctl+0x3e1/0x1480 kernel/events/core.c:4770 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #0 (bpf_event_mutex){+.+.}: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854 perf_event_free_bpf_prog kernel/events/core.c:8147 [inline] _free_event+0xbdb/0x10f0 kernel/events/core.c:4116 put_event+0x24/0x30 kernel/events/core.c:4204 perf_mmap_close+0x60d/0x1010 kernel/events/core.c:5172 remove_vma+0xb4/0x1b0 mm/mmap.c:172 remove_vma_list mm/mmap.c:2490 [inline] do_munmap+0x82a/0xdf0 mm/mmap.c:2731 mmap_region+0x59e/0x15a0 mm/mmap.c:1646 do_mmap+0x6c0/0xe00 mm/mmap.c:1483 do_mmap_pgoff include/linux/mm.h:2223 [inline] vm_mmap_pgoff+0x1de/0x280 mm/util.c:355 SYSC_mmap_pgoff mm/mmap.c:1533 [inline] SyS_mmap_pgoff+0x462/0x5f0 mm/mmap.c:1491 SYSC_mmap arch/x86/kernel/sys_x86_64.c:100 [inline] SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:91 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&mm->mmap_sem); lock(bpf_event_mutex); lock(&mm->mmap_sem); lock(bpf_event_mutex); *** DEADLOCK *** ====================================================== The bug is introduced by Commit f371b304f12e ("bpf/tracing: allow user space to query prog array on the same tp") where copy_to_user, which requires mm->mmap_sem, is called inside bpf_event_mutex lock. At the same time, during perf_event file descriptor close, mm->mmap_sem is held first and then subsequent perf_event_detach_bpf_prog needs bpf_event_mutex lock. Such a senario caused a deadlock. As suggested by Daniel, moving copy_to_user out of the bpf_event_mutex lock should fix the problem. Fixes: f371b304f12e ("bpf/tracing: allow user space to query prog array on the same tp") Reported-by: syzbot+dc5ca0e4c9bfafaf2bae@syzkaller.appspotmail.com Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-04-10 19:37:32 +03:00
u32 *ids, prog_cnt, ids_len;
bpf/tracing: allow user space to query prog array on the same tp Commit e87c6bc3852b ("bpf: permit multiple bpf attachments for a single perf event") added support to attach multiple bpf programs to a single perf event. Although this provides flexibility, users may want to know what other bpf programs attached to the same tp interface. Besides getting visibility for the underlying bpf system, such information may also help consolidate multiple bpf programs, understand potential performance issues due to a large array, and debug (e.g., one bpf program which overwrites return code may impact subsequent program results). Commit 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") utilized the existing perf ioctl interface and added the command PERF_EVENT_IOC_SET_BPF to attach a bpf program to a tracepoint. This patch adds a new ioctl command, given a perf event fd, to query the bpf program array attached to the same perf tracepoint event. The new uapi ioctl command: PERF_EVENT_IOC_QUERY_BPF The new uapi/linux/perf_event.h structure: struct perf_event_query_bpf { __u32 ids_len; __u32 prog_cnt; __u32 ids[0]; }; User space provides buffer "ids" for kernel to copy to. When returning from the kernel, the number of available programs in the array is set in "prog_cnt". The usage: struct perf_event_query_bpf *query = malloc(sizeof(*query) + sizeof(u32) * ids_len); query.ids_len = ids_len; err = ioctl(pmu_efd, PERF_EVENT_IOC_QUERY_BPF, query); if (err == 0) { /* query.prog_cnt is the number of available progs, * number of progs in ids: (ids_len == 0) ? 0 : query.prog_cnt */ } else if (errno == ENOSPC) { /* query.ids_len number of progs copied, * query.prog_cnt is the number of available progs */ } else { /* other errors */ } Signed-off-by: Yonghong Song <yhs@fb.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2017-12-11 22:39:02 +03:00
int ret;
trace/bpf_trace: Open access for CAP_PERFMON privileged process Open access to bpf_trace monitoring for CAP_PERFMON privileged process. Providing the access under CAP_PERFMON capability singly, without the rest of CAP_SYS_ADMIN credentials, excludes chances to misuse the credentials and makes operation more secure. CAP_PERFMON implements the principle of least privilege for performance monitoring and observability operations (POSIX IEEE 1003.1e 2.2.2.39 principle of least privilege: A security design principle that states that a process or program be granted only those privileges (e.g., capabilities) necessary to accomplish its legitimate function, and only for the time that such privileges are actually required) For backward compatibility reasons access to bpf_trace monitoring remains open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN usage for secure bpf_trace monitoring is discouraged with respect to CAP_PERFMON capability. Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com> Reviewed-by: James Morris <jamorris@linux.microsoft.com> Acked-by: Song Liu <songliubraving@fb.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Igor Lubashev <ilubashe@akamai.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Serge Hallyn <serge@hallyn.com> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: intel-gfx@lists.freedesktop.org Cc: linux-doc@vger.kernel.org Cc: linux-man@vger.kernel.org Cc: linux-security-module@vger.kernel.org Cc: selinux@vger.kernel.org Link: http://lore.kernel.org/lkml/c0a0ae47-8b6e-ff3e-416b-3cd1faaf71c0@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2020-04-02 11:48:54 +03:00
if (!perfmon_capable())
bpf/tracing: allow user space to query prog array on the same tp Commit e87c6bc3852b ("bpf: permit multiple bpf attachments for a single perf event") added support to attach multiple bpf programs to a single perf event. Although this provides flexibility, users may want to know what other bpf programs attached to the same tp interface. Besides getting visibility for the underlying bpf system, such information may also help consolidate multiple bpf programs, understand potential performance issues due to a large array, and debug (e.g., one bpf program which overwrites return code may impact subsequent program results). Commit 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") utilized the existing perf ioctl interface and added the command PERF_EVENT_IOC_SET_BPF to attach a bpf program to a tracepoint. This patch adds a new ioctl command, given a perf event fd, to query the bpf program array attached to the same perf tracepoint event. The new uapi ioctl command: PERF_EVENT_IOC_QUERY_BPF The new uapi/linux/perf_event.h structure: struct perf_event_query_bpf { __u32 ids_len; __u32 prog_cnt; __u32 ids[0]; }; User space provides buffer "ids" for kernel to copy to. When returning from the kernel, the number of available programs in the array is set in "prog_cnt". The usage: struct perf_event_query_bpf *query = malloc(sizeof(*query) + sizeof(u32) * ids_len); query.ids_len = ids_len; err = ioctl(pmu_efd, PERF_EVENT_IOC_QUERY_BPF, query); if (err == 0) { /* query.prog_cnt is the number of available progs, * number of progs in ids: (ids_len == 0) ? 0 : query.prog_cnt */ } else if (errno == ENOSPC) { /* query.ids_len number of progs copied, * query.prog_cnt is the number of available progs */ } else { /* other errors */ } Signed-off-by: Yonghong Song <yhs@fb.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2017-12-11 22:39:02 +03:00
return -EPERM;
if (event->attr.type != PERF_TYPE_TRACEPOINT)
return -EINVAL;
if (copy_from_user(&query, uquery, sizeof(query)))
return -EFAULT;
bpf/tracing: fix a deadlock in perf_event_detach_bpf_prog syzbot reported a possible deadlock in perf_event_detach_bpf_prog. The error details: ====================================================== WARNING: possible circular locking dependency detected 4.16.0-rc7+ #3 Not tainted ------------------------------------------------------ syz-executor7/24531 is trying to acquire lock: (bpf_event_mutex){+.+.}, at: [<000000008a849b07>] perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854 but task is already holding lock: (&mm->mmap_sem){++++}, at: [<0000000038768f87>] vm_mmap_pgoff+0x198/0x280 mm/util.c:353 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&mm->mmap_sem){++++}: __might_fault+0x13a/0x1d0 mm/memory.c:4571 _copy_to_user+0x2c/0xc0 lib/usercopy.c:25 copy_to_user include/linux/uaccess.h:155 [inline] bpf_prog_array_copy_info+0xf2/0x1c0 kernel/bpf/core.c:1694 perf_event_query_prog_array+0x1c7/0x2c0 kernel/trace/bpf_trace.c:891 _perf_ioctl kernel/events/core.c:4750 [inline] perf_ioctl+0x3e1/0x1480 kernel/events/core.c:4770 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #0 (bpf_event_mutex){+.+.}: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854 perf_event_free_bpf_prog kernel/events/core.c:8147 [inline] _free_event+0xbdb/0x10f0 kernel/events/core.c:4116 put_event+0x24/0x30 kernel/events/core.c:4204 perf_mmap_close+0x60d/0x1010 kernel/events/core.c:5172 remove_vma+0xb4/0x1b0 mm/mmap.c:172 remove_vma_list mm/mmap.c:2490 [inline] do_munmap+0x82a/0xdf0 mm/mmap.c:2731 mmap_region+0x59e/0x15a0 mm/mmap.c:1646 do_mmap+0x6c0/0xe00 mm/mmap.c:1483 do_mmap_pgoff include/linux/mm.h:2223 [inline] vm_mmap_pgoff+0x1de/0x280 mm/util.c:355 SYSC_mmap_pgoff mm/mmap.c:1533 [inline] SyS_mmap_pgoff+0x462/0x5f0 mm/mmap.c:1491 SYSC_mmap arch/x86/kernel/sys_x86_64.c:100 [inline] SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:91 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&mm->mmap_sem); lock(bpf_event_mutex); lock(&mm->mmap_sem); lock(bpf_event_mutex); *** DEADLOCK *** ====================================================== The bug is introduced by Commit f371b304f12e ("bpf/tracing: allow user space to query prog array on the same tp") where copy_to_user, which requires mm->mmap_sem, is called inside bpf_event_mutex lock. At the same time, during perf_event file descriptor close, mm->mmap_sem is held first and then subsequent perf_event_detach_bpf_prog needs bpf_event_mutex lock. Such a senario caused a deadlock. As suggested by Daniel, moving copy_to_user out of the bpf_event_mutex lock should fix the problem. Fixes: f371b304f12e ("bpf/tracing: allow user space to query prog array on the same tp") Reported-by: syzbot+dc5ca0e4c9bfafaf2bae@syzkaller.appspotmail.com Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-04-10 19:37:32 +03:00
ids_len = query.ids_len;
if (ids_len > BPF_TRACE_MAX_PROGS)
return -E2BIG;
bpf/tracing: fix a deadlock in perf_event_detach_bpf_prog syzbot reported a possible deadlock in perf_event_detach_bpf_prog. The error details: ====================================================== WARNING: possible circular locking dependency detected 4.16.0-rc7+ #3 Not tainted ------------------------------------------------------ syz-executor7/24531 is trying to acquire lock: (bpf_event_mutex){+.+.}, at: [<000000008a849b07>] perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854 but task is already holding lock: (&mm->mmap_sem){++++}, at: [<0000000038768f87>] vm_mmap_pgoff+0x198/0x280 mm/util.c:353 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&mm->mmap_sem){++++}: __might_fault+0x13a/0x1d0 mm/memory.c:4571 _copy_to_user+0x2c/0xc0 lib/usercopy.c:25 copy_to_user include/linux/uaccess.h:155 [inline] bpf_prog_array_copy_info+0xf2/0x1c0 kernel/bpf/core.c:1694 perf_event_query_prog_array+0x1c7/0x2c0 kernel/trace/bpf_trace.c:891 _perf_ioctl kernel/events/core.c:4750 [inline] perf_ioctl+0x3e1/0x1480 kernel/events/core.c:4770 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #0 (bpf_event_mutex){+.+.}: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854 perf_event_free_bpf_prog kernel/events/core.c:8147 [inline] _free_event+0xbdb/0x10f0 kernel/events/core.c:4116 put_event+0x24/0x30 kernel/events/core.c:4204 perf_mmap_close+0x60d/0x1010 kernel/events/core.c:5172 remove_vma+0xb4/0x1b0 mm/mmap.c:172 remove_vma_list mm/mmap.c:2490 [inline] do_munmap+0x82a/0xdf0 mm/mmap.c:2731 mmap_region+0x59e/0x15a0 mm/mmap.c:1646 do_mmap+0x6c0/0xe00 mm/mmap.c:1483 do_mmap_pgoff include/linux/mm.h:2223 [inline] vm_mmap_pgoff+0x1de/0x280 mm/util.c:355 SYSC_mmap_pgoff mm/mmap.c:1533 [inline] SyS_mmap_pgoff+0x462/0x5f0 mm/mmap.c:1491 SYSC_mmap arch/x86/kernel/sys_x86_64.c:100 [inline] SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:91 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&mm->mmap_sem); lock(bpf_event_mutex); lock(&mm->mmap_sem); lock(bpf_event_mutex); *** DEADLOCK *** ====================================================== The bug is introduced by Commit f371b304f12e ("bpf/tracing: allow user space to query prog array on the same tp") where copy_to_user, which requires mm->mmap_sem, is called inside bpf_event_mutex lock. At the same time, during perf_event file descriptor close, mm->mmap_sem is held first and then subsequent perf_event_detach_bpf_prog needs bpf_event_mutex lock. Such a senario caused a deadlock. As suggested by Daniel, moving copy_to_user out of the bpf_event_mutex lock should fix the problem. Fixes: f371b304f12e ("bpf/tracing: allow user space to query prog array on the same tp") Reported-by: syzbot+dc5ca0e4c9bfafaf2bae@syzkaller.appspotmail.com Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-04-10 19:37:32 +03:00
ids = kcalloc(ids_len, sizeof(u32), GFP_USER | __GFP_NOWARN);
if (!ids)
return -ENOMEM;
/*
* The above kcalloc returns ZERO_SIZE_PTR when ids_len = 0, which
* is required when user only wants to check for uquery->prog_cnt.
* There is no need to check for it since the case is handled
* gracefully in bpf_prog_array_copy_info.
*/
bpf/tracing: allow user space to query prog array on the same tp Commit e87c6bc3852b ("bpf: permit multiple bpf attachments for a single perf event") added support to attach multiple bpf programs to a single perf event. Although this provides flexibility, users may want to know what other bpf programs attached to the same tp interface. Besides getting visibility for the underlying bpf system, such information may also help consolidate multiple bpf programs, understand potential performance issues due to a large array, and debug (e.g., one bpf program which overwrites return code may impact subsequent program results). Commit 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") utilized the existing perf ioctl interface and added the command PERF_EVENT_IOC_SET_BPF to attach a bpf program to a tracepoint. This patch adds a new ioctl command, given a perf event fd, to query the bpf program array attached to the same perf tracepoint event. The new uapi ioctl command: PERF_EVENT_IOC_QUERY_BPF The new uapi/linux/perf_event.h structure: struct perf_event_query_bpf { __u32 ids_len; __u32 prog_cnt; __u32 ids[0]; }; User space provides buffer "ids" for kernel to copy to. When returning from the kernel, the number of available programs in the array is set in "prog_cnt". The usage: struct perf_event_query_bpf *query = malloc(sizeof(*query) + sizeof(u32) * ids_len); query.ids_len = ids_len; err = ioctl(pmu_efd, PERF_EVENT_IOC_QUERY_BPF, query); if (err == 0) { /* query.prog_cnt is the number of available progs, * number of progs in ids: (ids_len == 0) ? 0 : query.prog_cnt */ } else if (errno == ENOSPC) { /* query.ids_len number of progs copied, * query.prog_cnt is the number of available progs */ } else { /* other errors */ } Signed-off-by: Yonghong Song <yhs@fb.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2017-12-11 22:39:02 +03:00
mutex_lock(&bpf_event_mutex);
progs = bpf_event_rcu_dereference(event->tp_event->prog_array);
ret = bpf_prog_array_copy_info(progs, ids, ids_len, &prog_cnt);
bpf/tracing: allow user space to query prog array on the same tp Commit e87c6bc3852b ("bpf: permit multiple bpf attachments for a single perf event") added support to attach multiple bpf programs to a single perf event. Although this provides flexibility, users may want to know what other bpf programs attached to the same tp interface. Besides getting visibility for the underlying bpf system, such information may also help consolidate multiple bpf programs, understand potential performance issues due to a large array, and debug (e.g., one bpf program which overwrites return code may impact subsequent program results). Commit 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") utilized the existing perf ioctl interface and added the command PERF_EVENT_IOC_SET_BPF to attach a bpf program to a tracepoint. This patch adds a new ioctl command, given a perf event fd, to query the bpf program array attached to the same perf tracepoint event. The new uapi ioctl command: PERF_EVENT_IOC_QUERY_BPF The new uapi/linux/perf_event.h structure: struct perf_event_query_bpf { __u32 ids_len; __u32 prog_cnt; __u32 ids[0]; }; User space provides buffer "ids" for kernel to copy to. When returning from the kernel, the number of available programs in the array is set in "prog_cnt". The usage: struct perf_event_query_bpf *query = malloc(sizeof(*query) + sizeof(u32) * ids_len); query.ids_len = ids_len; err = ioctl(pmu_efd, PERF_EVENT_IOC_QUERY_BPF, query); if (err == 0) { /* query.prog_cnt is the number of available progs, * number of progs in ids: (ids_len == 0) ? 0 : query.prog_cnt */ } else if (errno == ENOSPC) { /* query.ids_len number of progs copied, * query.prog_cnt is the number of available progs */ } else { /* other errors */ } Signed-off-by: Yonghong Song <yhs@fb.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2017-12-11 22:39:02 +03:00
mutex_unlock(&bpf_event_mutex);
bpf/tracing: fix a deadlock in perf_event_detach_bpf_prog syzbot reported a possible deadlock in perf_event_detach_bpf_prog. The error details: ====================================================== WARNING: possible circular locking dependency detected 4.16.0-rc7+ #3 Not tainted ------------------------------------------------------ syz-executor7/24531 is trying to acquire lock: (bpf_event_mutex){+.+.}, at: [<000000008a849b07>] perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854 but task is already holding lock: (&mm->mmap_sem){++++}, at: [<0000000038768f87>] vm_mmap_pgoff+0x198/0x280 mm/util.c:353 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&mm->mmap_sem){++++}: __might_fault+0x13a/0x1d0 mm/memory.c:4571 _copy_to_user+0x2c/0xc0 lib/usercopy.c:25 copy_to_user include/linux/uaccess.h:155 [inline] bpf_prog_array_copy_info+0xf2/0x1c0 kernel/bpf/core.c:1694 perf_event_query_prog_array+0x1c7/0x2c0 kernel/trace/bpf_trace.c:891 _perf_ioctl kernel/events/core.c:4750 [inline] perf_ioctl+0x3e1/0x1480 kernel/events/core.c:4770 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #0 (bpf_event_mutex){+.+.}: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854 perf_event_free_bpf_prog kernel/events/core.c:8147 [inline] _free_event+0xbdb/0x10f0 kernel/events/core.c:4116 put_event+0x24/0x30 kernel/events/core.c:4204 perf_mmap_close+0x60d/0x1010 kernel/events/core.c:5172 remove_vma+0xb4/0x1b0 mm/mmap.c:172 remove_vma_list mm/mmap.c:2490 [inline] do_munmap+0x82a/0xdf0 mm/mmap.c:2731 mmap_region+0x59e/0x15a0 mm/mmap.c:1646 do_mmap+0x6c0/0xe00 mm/mmap.c:1483 do_mmap_pgoff include/linux/mm.h:2223 [inline] vm_mmap_pgoff+0x1de/0x280 mm/util.c:355 SYSC_mmap_pgoff mm/mmap.c:1533 [inline] SyS_mmap_pgoff+0x462/0x5f0 mm/mmap.c:1491 SYSC_mmap arch/x86/kernel/sys_x86_64.c:100 [inline] SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:91 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&mm->mmap_sem); lock(bpf_event_mutex); lock(&mm->mmap_sem); lock(bpf_event_mutex); *** DEADLOCK *** ====================================================== The bug is introduced by Commit f371b304f12e ("bpf/tracing: allow user space to query prog array on the same tp") where copy_to_user, which requires mm->mmap_sem, is called inside bpf_event_mutex lock. At the same time, during perf_event file descriptor close, mm->mmap_sem is held first and then subsequent perf_event_detach_bpf_prog needs bpf_event_mutex lock. Such a senario caused a deadlock. As suggested by Daniel, moving copy_to_user out of the bpf_event_mutex lock should fix the problem. Fixes: f371b304f12e ("bpf/tracing: allow user space to query prog array on the same tp") Reported-by: syzbot+dc5ca0e4c9bfafaf2bae@syzkaller.appspotmail.com Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-04-10 19:37:32 +03:00
if (copy_to_user(&uquery->prog_cnt, &prog_cnt, sizeof(prog_cnt)) ||
copy_to_user(uquery->ids, ids, ids_len * sizeof(u32)))
ret = -EFAULT;
kfree(ids);
bpf/tracing: allow user space to query prog array on the same tp Commit e87c6bc3852b ("bpf: permit multiple bpf attachments for a single perf event") added support to attach multiple bpf programs to a single perf event. Although this provides flexibility, users may want to know what other bpf programs attached to the same tp interface. Besides getting visibility for the underlying bpf system, such information may also help consolidate multiple bpf programs, understand potential performance issues due to a large array, and debug (e.g., one bpf program which overwrites return code may impact subsequent program results). Commit 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") utilized the existing perf ioctl interface and added the command PERF_EVENT_IOC_SET_BPF to attach a bpf program to a tracepoint. This patch adds a new ioctl command, given a perf event fd, to query the bpf program array attached to the same perf tracepoint event. The new uapi ioctl command: PERF_EVENT_IOC_QUERY_BPF The new uapi/linux/perf_event.h structure: struct perf_event_query_bpf { __u32 ids_len; __u32 prog_cnt; __u32 ids[0]; }; User space provides buffer "ids" for kernel to copy to. When returning from the kernel, the number of available programs in the array is set in "prog_cnt". The usage: struct perf_event_query_bpf *query = malloc(sizeof(*query) + sizeof(u32) * ids_len); query.ids_len = ids_len; err = ioctl(pmu_efd, PERF_EVENT_IOC_QUERY_BPF, query); if (err == 0) { /* query.prog_cnt is the number of available progs, * number of progs in ids: (ids_len == 0) ? 0 : query.prog_cnt */ } else if (errno == ENOSPC) { /* query.ids_len number of progs copied, * query.prog_cnt is the number of available progs */ } else { /* other errors */ } Signed-off-by: Yonghong Song <yhs@fb.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2017-12-11 22:39:02 +03:00
return ret;
}
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
extern struct bpf_raw_event_map __start__bpf_raw_tp[];
extern struct bpf_raw_event_map __stop__bpf_raw_tp[];
struct bpf_raw_event_map *bpf_get_raw_tracepoint(const char *name)
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
{
struct bpf_raw_event_map *btp = __start__bpf_raw_tp;
for (; btp < __stop__bpf_raw_tp; btp++) {
if (!strcmp(btp->tp->name, name))
return btp;
}
return bpf_get_raw_tracepoint_module(name);
}
void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp)
{
struct module *mod = __module_address((unsigned long)btp);
if (mod)
module_put(mod);
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
}
static __always_inline
void __bpf_trace_run(struct bpf_prog *prog, u64 *args)
{
cant_sleep();
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
rcu_read_lock();
(void) BPF_PROG_RUN(prog, args);
rcu_read_unlock();
}
#define UNPACK(...) __VA_ARGS__
#define REPEAT_1(FN, DL, X, ...) FN(X)
#define REPEAT_2(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_1(FN, DL, __VA_ARGS__)
#define REPEAT_3(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_2(FN, DL, __VA_ARGS__)
#define REPEAT_4(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_3(FN, DL, __VA_ARGS__)
#define REPEAT_5(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_4(FN, DL, __VA_ARGS__)
#define REPEAT_6(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_5(FN, DL, __VA_ARGS__)
#define REPEAT_7(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_6(FN, DL, __VA_ARGS__)
#define REPEAT_8(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_7(FN, DL, __VA_ARGS__)
#define REPEAT_9(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_8(FN, DL, __VA_ARGS__)
#define REPEAT_10(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_9(FN, DL, __VA_ARGS__)
#define REPEAT_11(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_10(FN, DL, __VA_ARGS__)
#define REPEAT_12(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_11(FN, DL, __VA_ARGS__)
#define REPEAT(X, FN, DL, ...) REPEAT_##X(FN, DL, __VA_ARGS__)
#define SARG(X) u64 arg##X
#define COPY(X) args[X] = arg##X
#define __DL_COM (,)
#define __DL_SEM (;)
#define __SEQ_0_11 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
#define BPF_TRACE_DEFN_x(x) \
void bpf_trace_run##x(struct bpf_prog *prog, \
REPEAT(x, SARG, __DL_COM, __SEQ_0_11)) \
{ \
u64 args[x]; \
REPEAT(x, COPY, __DL_SEM, __SEQ_0_11); \
__bpf_trace_run(prog, args); \
} \
EXPORT_SYMBOL_GPL(bpf_trace_run##x)
BPF_TRACE_DEFN_x(1);
BPF_TRACE_DEFN_x(2);
BPF_TRACE_DEFN_x(3);
BPF_TRACE_DEFN_x(4);
BPF_TRACE_DEFN_x(5);
BPF_TRACE_DEFN_x(6);
BPF_TRACE_DEFN_x(7);
BPF_TRACE_DEFN_x(8);
BPF_TRACE_DEFN_x(9);
BPF_TRACE_DEFN_x(10);
BPF_TRACE_DEFN_x(11);
BPF_TRACE_DEFN_x(12);
static int __bpf_probe_register(struct bpf_raw_event_map *btp, struct bpf_prog *prog)
{
struct tracepoint *tp = btp->tp;
/*
* check that program doesn't access arguments beyond what's
* available in this tracepoint
*/
if (prog->aux->max_ctx_offset > btp->num_args * sizeof(u64))
return -EINVAL;
if (prog->aux->max_tp_access > btp->writable_size)
return -EINVAL;
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
return tracepoint_probe_register(tp, (void *)btp->bpf_func, prog);
}
int bpf_probe_register(struct bpf_raw_event_map *btp, struct bpf_prog *prog)
{
bpf: fix potential deadlock in bpf_prog_register Lockdep found a potential deadlock between cpu_hotplug_lock, bpf_event_mutex, and cpuctx_mutex: [ 13.007000] WARNING: possible circular locking dependency detected [ 13.007587] 5.0.0-rc3-00018-g2fa53f892422-dirty #477 Not tainted [ 13.008124] ------------------------------------------------------ [ 13.008624] test_progs/246 is trying to acquire lock: [ 13.009030] 0000000094160d1d (tracepoints_mutex){+.+.}, at: tracepoint_probe_register_prio+0x2d/0x300 [ 13.009770] [ 13.009770] but task is already holding lock: [ 13.010239] 00000000d663ef86 (bpf_event_mutex){+.+.}, at: bpf_probe_register+0x1d/0x60 [ 13.010877] [ 13.010877] which lock already depends on the new lock. [ 13.010877] [ 13.011532] [ 13.011532] the existing dependency chain (in reverse order) is: [ 13.012129] [ 13.012129] -> #4 (bpf_event_mutex){+.+.}: [ 13.012582] perf_event_query_prog_array+0x9b/0x130 [ 13.013016] _perf_ioctl+0x3aa/0x830 [ 13.013354] perf_ioctl+0x2e/0x50 [ 13.013668] do_vfs_ioctl+0x8f/0x6a0 [ 13.014003] ksys_ioctl+0x70/0x80 [ 13.014320] __x64_sys_ioctl+0x16/0x20 [ 13.014668] do_syscall_64+0x4a/0x180 [ 13.015007] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 13.015469] [ 13.015469] -> #3 (&cpuctx_mutex){+.+.}: [ 13.015910] perf_event_init_cpu+0x5a/0x90 [ 13.016291] perf_event_init+0x1b2/0x1de [ 13.016654] start_kernel+0x2b8/0x42a [ 13.016995] secondary_startup_64+0xa4/0xb0 [ 13.017382] [ 13.017382] -> #2 (pmus_lock){+.+.}: [ 13.017794] perf_event_init_cpu+0x21/0x90 [ 13.018172] cpuhp_invoke_callback+0xb3/0x960 [ 13.018573] _cpu_up+0xa7/0x140 [ 13.018871] do_cpu_up+0xa4/0xc0 [ 13.019178] smp_init+0xcd/0xd2 [ 13.019483] kernel_init_freeable+0x123/0x24f [ 13.019878] kernel_init+0xa/0x110 [ 13.020201] ret_from_fork+0x24/0x30 [ 13.020541] [ 13.020541] -> #1 (cpu_hotplug_lock.rw_sem){++++}: [ 13.021051] static_key_slow_inc+0xe/0x20 [ 13.021424] tracepoint_probe_register_prio+0x28c/0x300 [ 13.021891] perf_trace_event_init+0x11f/0x250 [ 13.022297] perf_trace_init+0x6b/0xa0 [ 13.022644] perf_tp_event_init+0x25/0x40 [ 13.023011] perf_try_init_event+0x6b/0x90 [ 13.023386] perf_event_alloc+0x9a8/0xc40 [ 13.023754] __do_sys_perf_event_open+0x1dd/0xd30 [ 13.024173] do_syscall_64+0x4a/0x180 [ 13.024519] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 13.024968] [ 13.024968] -> #0 (tracepoints_mutex){+.+.}: [ 13.025434] __mutex_lock+0x86/0x970 [ 13.025764] tracepoint_probe_register_prio+0x2d/0x300 [ 13.026215] bpf_probe_register+0x40/0x60 [ 13.026584] bpf_raw_tracepoint_open.isra.34+0xa4/0x130 [ 13.027042] __do_sys_bpf+0x94f/0x1a90 [ 13.027389] do_syscall_64+0x4a/0x180 [ 13.027727] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 13.028171] [ 13.028171] other info that might help us debug this: [ 13.028171] [ 13.028807] Chain exists of: [ 13.028807] tracepoints_mutex --> &cpuctx_mutex --> bpf_event_mutex [ 13.028807] [ 13.029666] Possible unsafe locking scenario: [ 13.029666] [ 13.030140] CPU0 CPU1 [ 13.030510] ---- ---- [ 13.030875] lock(bpf_event_mutex); [ 13.031166] lock(&cpuctx_mutex); [ 13.031645] lock(bpf_event_mutex); [ 13.032135] lock(tracepoints_mutex); [ 13.032441] [ 13.032441] *** DEADLOCK *** [ 13.032441] [ 13.032911] 1 lock held by test_progs/246: [ 13.033239] #0: 00000000d663ef86 (bpf_event_mutex){+.+.}, at: bpf_probe_register+0x1d/0x60 [ 13.033909] [ 13.033909] stack backtrace: [ 13.034258] CPU: 1 PID: 246 Comm: test_progs Not tainted 5.0.0-rc3-00018-g2fa53f892422-dirty #477 [ 13.034964] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014 [ 13.035657] Call Trace: [ 13.035859] dump_stack+0x5f/0x8b [ 13.036130] print_circular_bug.isra.37+0x1ce/0x1db [ 13.036526] __lock_acquire+0x1158/0x1350 [ 13.036852] ? lock_acquire+0x98/0x190 [ 13.037154] lock_acquire+0x98/0x190 [ 13.037447] ? tracepoint_probe_register_prio+0x2d/0x300 [ 13.037876] __mutex_lock+0x86/0x970 [ 13.038167] ? tracepoint_probe_register_prio+0x2d/0x300 [ 13.038600] ? tracepoint_probe_register_prio+0x2d/0x300 [ 13.039028] ? __mutex_lock+0x86/0x970 [ 13.039337] ? __mutex_lock+0x24a/0x970 [ 13.039649] ? bpf_probe_register+0x1d/0x60 [ 13.039992] ? __bpf_trace_sched_wake_idle_without_ipi+0x10/0x10 [ 13.040478] ? tracepoint_probe_register_prio+0x2d/0x300 [ 13.040906] tracepoint_probe_register_prio+0x2d/0x300 [ 13.041325] bpf_probe_register+0x40/0x60 [ 13.041649] bpf_raw_tracepoint_open.isra.34+0xa4/0x130 [ 13.042068] ? __might_fault+0x3e/0x90 [ 13.042374] __do_sys_bpf+0x94f/0x1a90 [ 13.042678] do_syscall_64+0x4a/0x180 [ 13.042975] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 13.043382] RIP: 0033:0x7f23b10a07f9 [ 13.045155] RSP: 002b:00007ffdef42fdd8 EFLAGS: 00000202 ORIG_RAX: 0000000000000141 [ 13.045759] RAX: ffffffffffffffda RBX: 00007ffdef42ff70 RCX: 00007f23b10a07f9 [ 13.046326] RDX: 0000000000000070 RSI: 00007ffdef42fe10 RDI: 0000000000000011 [ 13.046893] RBP: 00007ffdef42fdf0 R08: 0000000000000038 R09: 00007ffdef42fe10 [ 13.047462] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 [ 13.048029] R13: 0000000000000016 R14: 00007f23b1db4690 R15: 0000000000000000 Since tracepoints_mutex will be taken in tracepoint_probe_register/unregister() there is no need to take bpf_event_mutex too. bpf_event_mutex is protecting modifications to prog array used in kprobe/perf bpf progs. bpf_raw_tracepoints don't need to take this mutex. Fixes: c4f6699dfcb8 ("bpf: introduce BPF_RAW_TRACEPOINT") Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-01-31 05:12:44 +03:00
return __bpf_probe_register(btp, prog);
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
}
int bpf_probe_unregister(struct bpf_raw_event_map *btp, struct bpf_prog *prog)
{
bpf: fix potential deadlock in bpf_prog_register Lockdep found a potential deadlock between cpu_hotplug_lock, bpf_event_mutex, and cpuctx_mutex: [ 13.007000] WARNING: possible circular locking dependency detected [ 13.007587] 5.0.0-rc3-00018-g2fa53f892422-dirty #477 Not tainted [ 13.008124] ------------------------------------------------------ [ 13.008624] test_progs/246 is trying to acquire lock: [ 13.009030] 0000000094160d1d (tracepoints_mutex){+.+.}, at: tracepoint_probe_register_prio+0x2d/0x300 [ 13.009770] [ 13.009770] but task is already holding lock: [ 13.010239] 00000000d663ef86 (bpf_event_mutex){+.+.}, at: bpf_probe_register+0x1d/0x60 [ 13.010877] [ 13.010877] which lock already depends on the new lock. [ 13.010877] [ 13.011532] [ 13.011532] the existing dependency chain (in reverse order) is: [ 13.012129] [ 13.012129] -> #4 (bpf_event_mutex){+.+.}: [ 13.012582] perf_event_query_prog_array+0x9b/0x130 [ 13.013016] _perf_ioctl+0x3aa/0x830 [ 13.013354] perf_ioctl+0x2e/0x50 [ 13.013668] do_vfs_ioctl+0x8f/0x6a0 [ 13.014003] ksys_ioctl+0x70/0x80 [ 13.014320] __x64_sys_ioctl+0x16/0x20 [ 13.014668] do_syscall_64+0x4a/0x180 [ 13.015007] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 13.015469] [ 13.015469] -> #3 (&cpuctx_mutex){+.+.}: [ 13.015910] perf_event_init_cpu+0x5a/0x90 [ 13.016291] perf_event_init+0x1b2/0x1de [ 13.016654] start_kernel+0x2b8/0x42a [ 13.016995] secondary_startup_64+0xa4/0xb0 [ 13.017382] [ 13.017382] -> #2 (pmus_lock){+.+.}: [ 13.017794] perf_event_init_cpu+0x21/0x90 [ 13.018172] cpuhp_invoke_callback+0xb3/0x960 [ 13.018573] _cpu_up+0xa7/0x140 [ 13.018871] do_cpu_up+0xa4/0xc0 [ 13.019178] smp_init+0xcd/0xd2 [ 13.019483] kernel_init_freeable+0x123/0x24f [ 13.019878] kernel_init+0xa/0x110 [ 13.020201] ret_from_fork+0x24/0x30 [ 13.020541] [ 13.020541] -> #1 (cpu_hotplug_lock.rw_sem){++++}: [ 13.021051] static_key_slow_inc+0xe/0x20 [ 13.021424] tracepoint_probe_register_prio+0x28c/0x300 [ 13.021891] perf_trace_event_init+0x11f/0x250 [ 13.022297] perf_trace_init+0x6b/0xa0 [ 13.022644] perf_tp_event_init+0x25/0x40 [ 13.023011] perf_try_init_event+0x6b/0x90 [ 13.023386] perf_event_alloc+0x9a8/0xc40 [ 13.023754] __do_sys_perf_event_open+0x1dd/0xd30 [ 13.024173] do_syscall_64+0x4a/0x180 [ 13.024519] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 13.024968] [ 13.024968] -> #0 (tracepoints_mutex){+.+.}: [ 13.025434] __mutex_lock+0x86/0x970 [ 13.025764] tracepoint_probe_register_prio+0x2d/0x300 [ 13.026215] bpf_probe_register+0x40/0x60 [ 13.026584] bpf_raw_tracepoint_open.isra.34+0xa4/0x130 [ 13.027042] __do_sys_bpf+0x94f/0x1a90 [ 13.027389] do_syscall_64+0x4a/0x180 [ 13.027727] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 13.028171] [ 13.028171] other info that might help us debug this: [ 13.028171] [ 13.028807] Chain exists of: [ 13.028807] tracepoints_mutex --> &cpuctx_mutex --> bpf_event_mutex [ 13.028807] [ 13.029666] Possible unsafe locking scenario: [ 13.029666] [ 13.030140] CPU0 CPU1 [ 13.030510] ---- ---- [ 13.030875] lock(bpf_event_mutex); [ 13.031166] lock(&cpuctx_mutex); [ 13.031645] lock(bpf_event_mutex); [ 13.032135] lock(tracepoints_mutex); [ 13.032441] [ 13.032441] *** DEADLOCK *** [ 13.032441] [ 13.032911] 1 lock held by test_progs/246: [ 13.033239] #0: 00000000d663ef86 (bpf_event_mutex){+.+.}, at: bpf_probe_register+0x1d/0x60 [ 13.033909] [ 13.033909] stack backtrace: [ 13.034258] CPU: 1 PID: 246 Comm: test_progs Not tainted 5.0.0-rc3-00018-g2fa53f892422-dirty #477 [ 13.034964] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014 [ 13.035657] Call Trace: [ 13.035859] dump_stack+0x5f/0x8b [ 13.036130] print_circular_bug.isra.37+0x1ce/0x1db [ 13.036526] __lock_acquire+0x1158/0x1350 [ 13.036852] ? lock_acquire+0x98/0x190 [ 13.037154] lock_acquire+0x98/0x190 [ 13.037447] ? tracepoint_probe_register_prio+0x2d/0x300 [ 13.037876] __mutex_lock+0x86/0x970 [ 13.038167] ? tracepoint_probe_register_prio+0x2d/0x300 [ 13.038600] ? tracepoint_probe_register_prio+0x2d/0x300 [ 13.039028] ? __mutex_lock+0x86/0x970 [ 13.039337] ? __mutex_lock+0x24a/0x970 [ 13.039649] ? bpf_probe_register+0x1d/0x60 [ 13.039992] ? __bpf_trace_sched_wake_idle_without_ipi+0x10/0x10 [ 13.040478] ? tracepoint_probe_register_prio+0x2d/0x300 [ 13.040906] tracepoint_probe_register_prio+0x2d/0x300 [ 13.041325] bpf_probe_register+0x40/0x60 [ 13.041649] bpf_raw_tracepoint_open.isra.34+0xa4/0x130 [ 13.042068] ? __might_fault+0x3e/0x90 [ 13.042374] __do_sys_bpf+0x94f/0x1a90 [ 13.042678] do_syscall_64+0x4a/0x180 [ 13.042975] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 13.043382] RIP: 0033:0x7f23b10a07f9 [ 13.045155] RSP: 002b:00007ffdef42fdd8 EFLAGS: 00000202 ORIG_RAX: 0000000000000141 [ 13.045759] RAX: ffffffffffffffda RBX: 00007ffdef42ff70 RCX: 00007f23b10a07f9 [ 13.046326] RDX: 0000000000000070 RSI: 00007ffdef42fe10 RDI: 0000000000000011 [ 13.046893] RBP: 00007ffdef42fdf0 R08: 0000000000000038 R09: 00007ffdef42fe10 [ 13.047462] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 [ 13.048029] R13: 0000000000000016 R14: 00007f23b1db4690 R15: 0000000000000000 Since tracepoints_mutex will be taken in tracepoint_probe_register/unregister() there is no need to take bpf_event_mutex too. bpf_event_mutex is protecting modifications to prog array used in kprobe/perf bpf progs. bpf_raw_tracepoints don't need to take this mutex. Fixes: c4f6699dfcb8 ("bpf: introduce BPF_RAW_TRACEPOINT") Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-01-31 05:12:44 +03:00
return tracepoint_probe_unregister(btp->tp, (void *)btp->bpf_func, prog);
bpf: introduce BPF_RAW_TRACEPOINT Introduce BPF_PROG_TYPE_RAW_TRACEPOINT bpf program type to access kernel internal arguments of the tracepoints in their raw form. >From bpf program point of view the access to the arguments look like: struct bpf_raw_tracepoint_args { __u64 args[0]; }; int bpf_prog(struct bpf_raw_tracepoint_args *ctx) { // program can read args[N] where N depends on tracepoint // and statically verified at program load+attach time } kprobe+bpf infrastructure allows programs access function arguments. This feature allows programs access raw tracepoint arguments. Similar to proposed 'dynamic ftrace events' there are no abi guarantees to what the tracepoints arguments are and what their meaning is. The program needs to type cast args properly and use bpf_probe_read() helper to access struct fields when argument is a pointer. For every tracepoint __bpf_trace_##call function is prepared. In assembler it looks like: (gdb) disassemble __bpf_trace_xdp_exception Dump of assembler code for function __bpf_trace_xdp_exception: 0xffffffff81132080 <+0>: mov %ecx,%ecx 0xffffffff81132082 <+2>: jmpq 0xffffffff811231f0 <bpf_trace_run3> where TRACE_EVENT(xdp_exception, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, u32 act), The above assembler snippet is casting 32-bit 'act' field into 'u64' to pass into bpf_trace_run3(), while 'dev' and 'xdp' args are passed as-is. All of ~500 of __bpf_trace_*() functions are only 5-10 byte long and in total this approach adds 7k bytes to .text. This approach gives the lowest possible overhead while calling trace_xdp_exception() from kernel C code and transitioning into bpf land. Since tracepoint+bpf are used at speeds of 1M+ events per second this is valuable optimization. The new BPF_RAW_TRACEPOINT_OPEN sys_bpf command is introduced that returns anon_inode FD of 'bpf-raw-tracepoint' object. The user space looks like: // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type prog_fd = bpf_prog_load(...); // receive anon_inode fd for given bpf_raw_tracepoint with prog attached raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd); Ctrl-C of tracing daemon or cmdline tool that uses this feature will automatically detach bpf program, unload it and unregister tracepoint probe. On the kernel side the __bpf_raw_tp_map section of pointers to tracepoint definition and to __bpf_trace_*() probe function is used to find a tracepoint with "xdp_exception" name and corresponding __bpf_trace_xdp_exception() probe function which are passed to tracepoint_probe_register() to connect probe with tracepoint. Addition of bpf_raw_tracepoint doesn't interfere with ftrace and perf tracepoint mechanisms. perf_event_open() can be used in parallel on the same tracepoint. Multiple bpf_raw_tracepoint_open("xdp_exception", prog_fd) are permitted. Each with its own bpf program. The kernel will execute all tracepoint probes and all attached bpf programs. In the future bpf_raw_tracepoints can be extended with query/introspection logic. __bpf_raw_tp_map section logic was contributed by Steven Rostedt Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-03-28 22:05:37 +03:00
}
int bpf_get_perf_event_info(const struct perf_event *event, u32 *prog_id,
u32 *fd_type, const char **buf,
u64 *probe_offset, u64 *probe_addr)
{
bool is_tracepoint, is_syscall_tp;
struct bpf_prog *prog;
int flags, err = 0;
prog = event->prog;
if (!prog)
return -ENOENT;
/* not supporting BPF_PROG_TYPE_PERF_EVENT yet */
if (prog->type == BPF_PROG_TYPE_PERF_EVENT)
return -EOPNOTSUPP;
*prog_id = prog->aux->id;
flags = event->tp_event->flags;
is_tracepoint = flags & TRACE_EVENT_FL_TRACEPOINT;
is_syscall_tp = is_syscall_trace_event(event->tp_event);
if (is_tracepoint || is_syscall_tp) {
*buf = is_tracepoint ? event->tp_event->tp->name
: event->tp_event->name;
*fd_type = BPF_FD_TYPE_TRACEPOINT;
*probe_offset = 0x0;
*probe_addr = 0x0;
} else {
/* kprobe/uprobe */
err = -EOPNOTSUPP;
#ifdef CONFIG_KPROBE_EVENTS
if (flags & TRACE_EVENT_FL_KPROBE)
err = bpf_get_kprobe_info(event, fd_type, buf,
probe_offset, probe_addr,
event->attr.type == PERF_TYPE_TRACEPOINT);
#endif
#ifdef CONFIG_UPROBE_EVENTS
if (flags & TRACE_EVENT_FL_UPROBE)
err = bpf_get_uprobe_info(event, fd_type, buf,
probe_offset,
event->attr.type == PERF_TYPE_TRACEPOINT);
#endif
}
return err;
}
static int __init send_signal_irq_work_init(void)
{
int cpu;
struct send_signal_irq_work *work;
for_each_possible_cpu(cpu) {
work = per_cpu_ptr(&send_signal_work, cpu);
init_irq_work(&work->irq_work, do_bpf_send_signal);
}
return 0;
}
subsys_initcall(send_signal_irq_work_init);
#ifdef CONFIG_MODULES
static int bpf_event_notify(struct notifier_block *nb, unsigned long op,
void *module)
{
struct bpf_trace_module *btm, *tmp;
struct module *mod = module;
int ret = 0;
if (mod->num_bpf_raw_events == 0 ||
(op != MODULE_STATE_COMING && op != MODULE_STATE_GOING))
goto out;
mutex_lock(&bpf_module_mutex);
switch (op) {
case MODULE_STATE_COMING:
btm = kzalloc(sizeof(*btm), GFP_KERNEL);
if (btm) {
btm->module = module;
list_add(&btm->list, &bpf_trace_modules);
} else {
ret = -ENOMEM;
}
break;
case MODULE_STATE_GOING:
list_for_each_entry_safe(btm, tmp, &bpf_trace_modules, list) {
if (btm->module == module) {
list_del(&btm->list);
kfree(btm);
break;
}
}
break;
}
mutex_unlock(&bpf_module_mutex);
out:
return notifier_from_errno(ret);
}
static struct notifier_block bpf_module_nb = {
.notifier_call = bpf_event_notify,
};
static int __init bpf_event_init(void)
{
register_module_notifier(&bpf_module_nb);
return 0;
}
fs_initcall(bpf_event_init);
#endif /* CONFIG_MODULES */