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WSL2-Linux-Kernel
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bpftool: Use syscall/loader program in "prog load" and "gen skeleton" command. 

Add -L flag to bpftool to use libbpf gen_trace facility and syscall/loader program
for skeleton generation and program loading.

"bpftool gen skeleton -L" command will generate a "light skeleton" or "loader skeleton"
that is similar to existing skeleton, but has one major difference:
$ bpftool gen skeleton lsm.o > lsm.skel.h
$ bpftool gen skeleton -L lsm.o > lsm.lskel.h
$ diff lsm.skel.h lsm.lskel.h
@@ -5,34 +4,34 @@
 #define __LSM_SKEL_H__

 #include <stdlib.h>
-#include <bpf/libbpf.h>
+#include <bpf/bpf.h>

The light skeleton does not use majority of libbpf infrastructure.
It doesn't need libelf. It doesn't parse .o file.
It only needs few sys_bpf wrappers. All of them are in bpf/bpf.h file.
In future libbpf/bpf.c can be inlined into bpf.h, so not even libbpf.a would be
needed to work with light skeleton.

"bpftool prog load -L file.o" command is introduced for debugging of syscall/loader
program generation. Just like the same command without -L it will try to load
the programs from file.o into the kernel. It won't even try to pin them.

"bpftool prog load -L -d file.o" command will provide additional debug messages
on how syscall/loader program was generated.
Also the execution of syscall/loader program will use bpf_trace_printk() for
each step of loading BTF, creating maps, and loading programs.
The user can do "cat /.../trace_pipe" for further debug.

An example of fexit_sleep.lskel.h generated from progs/fexit_sleep.c:
struct fexit_sleep {
	struct bpf_loader_ctx ctx;
	struct {
		struct bpf_map_desc bss;
	} maps;
	struct {
		struct bpf_prog_desc nanosleep_fentry;
		struct bpf_prog_desc nanosleep_fexit;
	} progs;
	struct {
		int nanosleep_fentry_fd;
		int nanosleep_fexit_fd;
	} links;
	struct fexit_sleep__bss {
		int pid;
		int fentry_cnt;
		int fexit_cnt;
	} *bss;
};

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-18-alexei.starovoitov@gmail.com
This commit is contained in:
Alexei Starovoitov 2021-05-13 17:36:19 -07:00 коммит произвёл Daniel Borkmann
Родитель 7723256bf2
Коммит d510296d33
6 изменённых файлов: 482 добавлений и 24 удалений
Показать статистику Скачать Patch файл Скачать Diff файл Показать все файлы Свернуть все файлы

2
tools/bpf/bpftool/Makefile
Просмотреть файл

@ -136,7 +136,7 @@ endif
BPFTOOL_BOOTSTRAP := $(BOOTSTRAP_OUTPUT)bpftool
BOOTSTRAP_OBJS = $(addprefix $(BOOTSTRAP_OUTPUT),main.o common.o json_writer.o gen.o btf.o)
BOOTSTRAP_OBJS = $(addprefix $(BOOTSTRAP_OUTPUT),main.o common.o json_writer.o gen.o btf.o xlated_dumper.o btf_dumper.o) $(OUTPUT)disasm.o
OBJS = $(patsubst %.c,$(OUTPUT)%.o,$(SRCS)) $(OUTPUT)disasm.o
VMLINUX_BTF_PATHS ?= $(if $(O),$(O)/vmlinux) \

386
tools/bpf/bpftool/gen.c
Просмотреть файл

@ -18,6 +18,7 @@
#include <sys/stat.h>
#include <sys/mman.h>
#include <bpf/btf.h>
#include <bpf/bpf_gen_internal.h>
#include "json_writer.h"
#include "main.h"
@ -274,6 +275,327 @@ static void codegen(const char *template, ...)
free(s);
}
static void print_hex(const char *data, int data_sz)
{
int i, len;
for (i = 0, len = 0; i < data_sz; i++) {
int w = data[i] ? 4 : 2;
len += w;
if (len > 78) {
printf("\\\n");
len = w;
}
if (!data[i])
printf("\\0");
else
printf("\\x%02x", (unsigned char)data[i]);
}
}
static size_t bpf_map_mmap_sz(const struct bpf_map *map)
{
long page_sz = sysconf(_SC_PAGE_SIZE);
size_t map_sz;
map_sz = (size_t)roundup(bpf_map__value_size(map), 8) * bpf_map__max_entries(map);
map_sz = roundup(map_sz, page_sz);
return map_sz;
}
static void codegen_attach_detach(struct bpf_object *obj, const char *obj_name)
{
struct bpf_program *prog;
bpf_object__for_each_program(prog, obj) {
const char *tp_name;
codegen("\
\n\
\n\
static inline int \n\
%1$s__%2$s__attach(struct %1$s *skel) \n\
{ \n\
int prog_fd = skel->progs.%2$s.prog_fd; \n\
", obj_name, bpf_program__name(prog));
switch (bpf_program__get_type(prog)) {
case BPF_PROG_TYPE_RAW_TRACEPOINT:
tp_name = strchr(bpf_program__section_name(prog), '/') + 1;
printf("\tint fd = bpf_raw_tracepoint_open(\"%s\", prog_fd);\n", tp_name);
break;
case BPF_PROG_TYPE_TRACING:
printf("\tint fd = bpf_raw_tracepoint_open(NULL, prog_fd);\n");
break;
default:
printf("\tint fd = ((void)prog_fd, 0); /* auto-attach not supported */\n");
break;
}
codegen("\
\n\
\n\
if (fd > 0) \n\
skel->links.%1$s_fd = fd; \n\
return fd; \n\
} \n\
", bpf_program__name(prog));
}
codegen("\
\n\
\n\
static inline int \n\
%1$s__attach(struct %1$s *skel) \n\
{ \n\
int ret = 0; \n\
\n\
", obj_name);
bpf_object__for_each_program(prog, obj) {
codegen("\
\n\
ret = ret < 0 ? ret : %1$s__%2$s__attach(skel); \n\
", obj_name, bpf_program__name(prog));
}
codegen("\
\n\
return ret < 0 ? ret : 0; \n\
} \n\
\n\
static inline void \n\
%1$s__detach(struct %1$s *skel) \n\
{ \n\
", obj_name);
bpf_object__for_each_program(prog, obj) {
codegen("\
\n\
skel_closenz(skel->links.%1$s_fd); \n\
", bpf_program__name(prog));
}
codegen("\
\n\
} \n\
");
}
static void codegen_destroy(struct bpf_object *obj, const char *obj_name)
{
struct bpf_program *prog;
struct bpf_map *map;
codegen("\
\n\
static void \n\
%1$s__destroy(struct %1$s *skel) \n\
{ \n\
if (!skel) \n\
return; \n\
%1$s__detach(skel); \n\
",
obj_name);
bpf_object__for_each_program(prog, obj) {
codegen("\
\n\
skel_closenz(skel->progs.%1$s.prog_fd); \n\
", bpf_program__name(prog));
}
bpf_object__for_each_map(map, obj) {
const char * ident;
ident = get_map_ident(map);
if (!ident)
continue;
if (bpf_map__is_internal(map) &&
(bpf_map__def(map)->map_flags & BPF_F_MMAPABLE))
printf("\tmunmap(skel->%1$s, %2$zd);\n",
ident, bpf_map_mmap_sz(map));
codegen("\
\n\
skel_closenz(skel->maps.%1$s.map_fd); \n\
", ident);
}
codegen("\
\n\
free(skel); \n\
} \n\
",
obj_name);
}
static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *header_guard)
{
struct bpf_object_load_attr load_attr = {};
DECLARE_LIBBPF_OPTS(gen_loader_opts, opts);
struct bpf_map *map;
int err = 0;
err = bpf_object__gen_loader(obj, &opts);
if (err)
return err;
load_attr.obj = obj;
if (verifier_logs)
/* log_level1 + log_level2 + stats, but not stable UAPI */
load_attr.log_level = 1 + 2 + 4;
err = bpf_object__load_xattr(&load_attr);
if (err) {
p_err("failed to load object file");
goto out;
}
/* If there was no error during load then gen_loader_opts
* are populated with the loader program.
*/
/* finish generating 'struct skel' */
codegen("\
\n\
}; \n\
", obj_name);
codegen_attach_detach(obj, obj_name);
codegen_destroy(obj, obj_name);
codegen("\
\n\
static inline struct %1$s * \n\
%1$s__open(void) \n\
{ \n\
struct %1$s *skel; \n\
\n\
skel = calloc(sizeof(*skel), 1); \n\
if (!skel) \n\
goto cleanup; \n\
skel->ctx.sz = (void *)&skel->links - (void *)skel; \n\
",
obj_name, opts.data_sz);
bpf_object__for_each_map(map, obj) {
const char *ident;
const void *mmap_data = NULL;
size_t mmap_size = 0;
ident = get_map_ident(map);
if (!ident)
continue;
if (!bpf_map__is_internal(map) ||
!(bpf_map__def(map)->map_flags & BPF_F_MMAPABLE))
continue;
codegen("\
\n\
skel->%1$s = \n\
mmap(NULL, %2$zd, PROT_READ | PROT_WRITE,\n\
MAP_SHARED | MAP_ANONYMOUS, -1, 0); \n\
if (skel->%1$s == (void *) -1) \n\
goto cleanup; \n\
memcpy(skel->%1$s, (void *)\"\\ \n\
", ident, bpf_map_mmap_sz(map));
mmap_data = bpf_map__initial_value(map, &mmap_size);
print_hex(mmap_data, mmap_size);
printf("\", %2$zd);\n"
"\tskel->maps.%1$s.initial_value = (__u64)(long)skel->%1$s;\n",
ident, mmap_size);
}
codegen("\
\n\
return skel; \n\
cleanup: \n\
%1$s__destroy(skel); \n\
return NULL; \n\
} \n\
\n\
static inline int \n\
%1$s__load(struct %1$s *skel) \n\
{ \n\
struct bpf_load_and_run_opts opts = {}; \n\
int err; \n\
\n\
opts.ctx = (struct bpf_loader_ctx *)skel; \n\
opts.data_sz = %2$d; \n\
opts.data = (void *)\"\\ \n\
",
obj_name, opts.data_sz);
print_hex(opts.data, opts.data_sz);
codegen("\
\n\
\"; \n\
");
codegen("\
\n\
opts.insns_sz = %d; \n\
opts.insns = (void *)\"\\ \n\
",
opts.insns_sz);
print_hex(opts.insns, opts.insns_sz);
codegen("\
\n\
\"; \n\
err = bpf_load_and_run(&opts); \n\
if (err < 0) \n\
return err; \n\
", obj_name);
bpf_object__for_each_map(map, obj) {
const char *ident, *mmap_flags;
ident = get_map_ident(map);
if (!ident)
continue;
if (!bpf_map__is_internal(map) ||
!(bpf_map__def(map)->map_flags & BPF_F_MMAPABLE))
continue;
if (bpf_map__def(map)->map_flags & BPF_F_RDONLY_PROG)
mmap_flags = "PROT_READ";
else
mmap_flags = "PROT_READ | PROT_WRITE";
printf("\tskel->%1$s =\n"
"\t\tmmap(skel->%1$s, %2$zd, %3$s, MAP_SHARED | MAP_FIXED,\n"
"\t\t\tskel->maps.%1$s.map_fd, 0);\n",
ident, bpf_map_mmap_sz(map), mmap_flags);
}
codegen("\
\n\
return 0; \n\
} \n\
\n\
static inline struct %1$s * \n\
%1$s__open_and_load(void) \n\
{ \n\
struct %1$s *skel; \n\
\n\
skel = %1$s__open(); \n\
if (!skel) \n\
return NULL; \n\
if (%1$s__load(skel)) { \n\
%1$s__destroy(skel); \n\
return NULL; \n\
} \n\
return skel; \n\
} \n\
", obj_name);
codegen("\
\n\
\n\
#endif /* %s */ \n\
",
header_guard);
err = 0;
out:
return err;
}
static int do_skeleton(int argc, char **argv)
{
char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SKEL_H__")];
@ -283,7 +605,7 @@ static int do_skeleton(int argc, char **argv)
struct bpf_object *obj = NULL;
const char *file, *ident;
struct bpf_program *prog;
int fd, len, err = -1;
int fd, err = -1;
struct bpf_map *map;
struct btf *btf;
struct stat st;
@ -365,7 +687,25 @@ static int do_skeleton(int argc, char **argv)
}
get_header_guard(header_guard, obj_name);
codegen("\
if (use_loader) {
codegen("\
\n\
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ \n\
/* THIS FILE IS AUTOGENERATED! */ \n\
#ifndef %2$s \n\
#define %2$s \n\
\n\
#include <stdlib.h> \n\
#include <bpf/bpf.h> \n\
#include <bpf/skel_internal.h> \n\
\n\
struct %1$s { \n\
struct bpf_loader_ctx ctx; \n\
",
obj_name, header_guard
);
} else {
codegen("\
\n\
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ \n\
\n\
@ -381,7 +721,8 @@ static int do_skeleton(int argc, char **argv)
struct bpf_object *obj; \n\
",
obj_name, header_guard
);
);
}
if (map_cnt) {
printf("\tstruct {\n");
@ -389,7 +730,10 @@ static int do_skeleton(int argc, char **argv)
ident = get_map_ident(map);
if (!ident)
continue;
printf("\t\tstruct bpf_map *%s;\n", ident);
if (use_loader)
printf("\t\tstruct bpf_map_desc %s;\n", ident);
else
printf("\t\tstruct bpf_map *%s;\n", ident);
}
printf("\t} maps;\n");
}
@ -397,14 +741,22 @@ static int do_skeleton(int argc, char **argv)
if (prog_cnt) {
printf("\tstruct {\n");
bpf_object__for_each_program(prog, obj) {
printf("\t\tstruct bpf_program *%s;\n",
bpf_program__name(prog));
if (use_loader)
printf("\t\tstruct bpf_prog_desc %s;\n",
bpf_program__name(prog));
else
printf("\t\tstruct bpf_program *%s;\n",
bpf_program__name(prog));
}
printf("\t} progs;\n");
printf("\tstruct {\n");
bpf_object__for_each_program(prog, obj) {
printf("\t\tstruct bpf_link *%s;\n",
bpf_program__name(prog));
if (use_loader)
printf("\t\tint %s_fd;\n",
bpf_program__name(prog));
else
printf("\t\tstruct bpf_link *%s;\n",
bpf_program__name(prog));
}
printf("\t} links;\n");
}
@ -415,6 +767,10 @@ static int do_skeleton(int argc, char **argv)
if (err)
goto out;
}
if (use_loader) {
err = gen_trace(obj, obj_name, header_guard);
goto out;
}
codegen("\
\n\
@ -584,19 +940,7 @@ static int do_skeleton(int argc, char **argv)
file_sz);
/* embed contents of BPF object file */
for (i = 0, len = 0; i < file_sz; i++) {
int w = obj_data[i] ? 4 : 2;
len += w;
if (len > 78) {
printf("\\\n");
len = w;
}
if (!obj_data[i])
printf("\\0");
else
printf("\\x%02x", (unsigned char)obj_data[i]);
}
print_hex(obj_data, file_sz);
codegen("\
\n\

7
tools/bpf/bpftool/main.c
Просмотреть файл

@ -29,6 +29,7 @@ bool show_pinned;
bool block_mount;
bool verifier_logs;
bool relaxed_maps;
bool use_loader;
struct btf *base_btf;
struct pinned_obj_table prog_table;
struct pinned_obj_table map_table;
@ -392,6 +393,7 @@ int main(int argc, char **argv)
{ "mapcompat", no_argument, NULL, 'm' },
{ "nomount", no_argument, NULL, 'n' },
{ "debug", no_argument, NULL, 'd' },
{ "use-loader", no_argument, NULL, 'L' },
{ "base-btf", required_argument, NULL, 'B' },
{ 0 }
};
@ -409,7 +411,7 @@ int main(int argc, char **argv)
hash_init(link_table.table);
opterr = 0;
while ((opt = getopt_long(argc, argv, "VhpjfmndB:",
while ((opt = getopt_long(argc, argv, "VhpjfLmndB:",
options, NULL)) >= 0) {
switch (opt) {
case 'V':
@ -452,6 +454,9 @@ int main(int argc, char **argv)
return -1;
}
break;
case 'L':
use_loader = true;
break;
default:
p_err("unrecognized option '%s'", argv[optind - 1]);
if (json_output)

1
tools/bpf/bpftool/main.h
Просмотреть файл

@ -90,6 +90,7 @@ extern bool show_pids;
extern bool block_mount;
extern bool verifier_logs;
extern bool relaxed_maps;
extern bool use_loader;
extern struct btf *base_btf;
extern struct pinned_obj_table prog_table;
extern struct pinned_obj_table map_table;

107
tools/bpf/bpftool/prog.c
Просмотреть файл

@ -16,6 +16,7 @@
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <dirent.h>
#include <linux/err.h>
#include <linux/perf_event.h>
@ -24,6 +25,8 @@
#include <bpf/bpf.h>
#include <bpf/btf.h>
#include <bpf/libbpf.h>
#include <bpf/bpf_gen_internal.h>
#include <bpf/skel_internal.h>
#include "cfg.h"
#include "main.h"
@ -1499,7 +1502,7 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
set_max_rlimit();
obj = bpf_object__open_file(file, &open_opts);
if (IS_ERR_OR_NULL(obj)) {
if (libbpf_get_error(obj)) {
p_err("failed to open object file");
goto err_free_reuse_maps;
}
@ -1645,8 +1648,110 @@ err_free_reuse_maps:
return -1;
}
static int count_open_fds(void)
{
DIR *dp = opendir("/proc/self/fd");
struct dirent *de;
int cnt = -3;
if (!dp)
return -1;
while ((de = readdir(dp)))
cnt++;
closedir(dp);
return cnt;
}
static int try_loader(struct gen_loader_opts *gen)
{
struct bpf_load_and_run_opts opts = {};
struct bpf_loader_ctx *ctx;
int ctx_sz = sizeof(*ctx) + 64 * max(sizeof(struct bpf_map_desc),
sizeof(struct bpf_prog_desc));
int log_buf_sz = (1u << 24) - 1;
int err, fds_before, fd_delta;
char *log_buf;
ctx = alloca(ctx_sz);
memset(ctx, 0, ctx_sz);
ctx->sz = ctx_sz;
ctx->log_level = 1;
ctx->log_size = log_buf_sz;
log_buf = malloc(log_buf_sz);
if (!log_buf)
return -ENOMEM;
ctx->log_buf = (long) log_buf;
opts.ctx = ctx;
opts.data = gen->data;
opts.data_sz = gen->data_sz;
opts.insns = gen->insns;
opts.insns_sz = gen->insns_sz;
fds_before = count_open_fds();
err = bpf_load_and_run(&opts);
fd_delta = count_open_fds() - fds_before;
if (err < 0) {
fprintf(stderr, "err %d\n%s\n%s", err, opts.errstr, log_buf);
if (fd_delta)
fprintf(stderr, "loader prog leaked %d FDs\n",
fd_delta);
}
free(log_buf);
return err;
}
static int do_loader(int argc, char **argv)
{
DECLARE_LIBBPF_OPTS(bpf_object_open_opts, open_opts);
DECLARE_LIBBPF_OPTS(gen_loader_opts, gen);
struct bpf_object_load_attr load_attr = {};
struct bpf_object *obj;
const char *file;
int err = 0;
if (!REQ_ARGS(1))
return -1;
file = GET_ARG();
obj = bpf_object__open_file(file, &open_opts);
if (libbpf_get_error(obj)) {
p_err("failed to open object file");
goto err_close_obj;
}
err = bpf_object__gen_loader(obj, &gen);
if (err)
goto err_close_obj;
load_attr.obj = obj;
if (verifier_logs)
/* log_level1 + log_level2 + stats, but not stable UAPI */
load_attr.log_level = 1 + 2 + 4;
err = bpf_object__load_xattr(&load_attr);
if (err) {
p_err("failed to load object file");
goto err_close_obj;
}
if (verifier_logs) {
struct dump_data dd = {};
kernel_syms_load(&dd);
dump_xlated_plain(&dd, (void *)gen.insns, gen.insns_sz, false, false);
kernel_syms_destroy(&dd);
}
err = try_loader(&gen);
err_close_obj:
bpf_object__close(obj);
return err;
}
static int do_load(int argc, char **argv)
{
if (use_loader)
return do_loader(argc, argv);
return load_with_options(argc, argv, true);
}

3
tools/bpf/bpftool/xlated_dumper.c
Просмотреть файл

@ -196,6 +196,9 @@ static const char *print_imm(void *private_data,
else if (insn->src_reg == BPF_PSEUDO_MAP_VALUE)
snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
"map[id:%u][0]+%u", insn->imm, (insn + 1)->imm);
else if (insn->src_reg == BPF_PSEUDO_MAP_IDX_VALUE)
snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
"map[idx:%u]+%u", insn->imm, (insn + 1)->imm);
else if (insn->src_reg == BPF_PSEUDO_FUNC)
snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
"subprog[%+d]", insn->imm);