KP Singh ae24082331 bpf: Introduce BPF_MODIFY_RETURN ... When multiple programs are attached, each program receives the return value from the previous program on the stack and the last program provides the return value to the attached function. The fmod_ret bpf programs are run after the fentry programs and before the fexit programs. The original function is only called if all the fmod_ret programs return 0 to avoid any unintended side-effects. The success value, i.e. 0 is not currently configurable but can be made so where user-space can specify it at load time. For example: int func_to_be_attached(int a, int b) { <--- do_fentry do_fmod_ret: <update ret by calling fmod_ret> if (ret != 0) goto do_fexit; original_function: <side_effects_happen_here> } <--- do_fexit The fmod_ret program attached to this function can be defined as: SEC("fmod_ret/func_to_be_attached") int BPF_PROG(func_name, int a, int b, int ret) { // This will skip the original function logic. return 1; } The first fmod_ret program is passed 0 in its return argument. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200304191853.1529-4-kpsingh@chromium.org		2020-03-04 13:41:05 -08:00
..
bpf	bpf: Introduce BPF_MODIFY_RETURN	2020-03-04 13:41:05 -08:00
cgroup	Merge branch 'for-5.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup	2020-02-10 17:07:05 -08:00
configs	…
debug	Revert "kdb: Get rid of confusing diag msg from "rd" if current task has no regs"	2020-02-06 11:40:09 +00:00
dma	dma-direct: improve DMA mask overflow reporting	2020-02-05 18:53:41 +01:00
events	perf/bpf: Remove preempt disable around BPF invocation	2020-02-24 16:18:20 -08:00
gcov	Revert "um: Enable CONFIG_CONSTRUCTORS"	2020-01-19 22:42:06 +01:00
irq	genirq/proc: Reject invalid affinity masks (again)	2020-02-14 09:43:17 +01:00
livepatch	New tracing features:	2019-11-27 11:42:01 -08:00
locking	proc: convert everything to "struct proc_ops"	2020-02-04 03:05:26 +00:00
power	ACPI: PM: s2idle: Avoid possible race related to the EC GPE	2020-02-11 10:11:02 +01:00
printk	printk: fix exclusive_console replaying	2020-01-02 16:15:04 +01:00
rcu	rcu: Forgive slow expedited grace periods at boot time	2020-01-25 12:00:40 -08:00
sched	Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2020-02-15 12:51:22 -08:00
time	y2038: remove unused time32 interfaces	2020-02-21 11:22:15 -08:00
trace	Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next	2020-02-29 15:53:35 -08:00
.gitignore	…
Kconfig.freezer	…
Kconfig.hz	…
Kconfig.locks	sched/rt, locking: Use CONFIG_PREEMPTION	2019-12-08 14:37:36 +01:00
Kconfig.preempt	sched/Kconfig: Fix spelling mistake in user-visible help text	2019-11-12 11:35:32 +01:00
Makefile	kcov: ignore fault-inject and stacktrace	2020-01-31 10:30:41 -08:00
acct.c	acct: stop using get_seconds()	2019-12-18 18:07:31 +01:00
async.c	…
audit.c	audit: always check the netlink payload length in audit_receive_msg()	2020-02-24 16:38:57 -05:00
audit.h	…
audit_fsnotify.c	…
audit_tree.c	…
audit_watch.c	audit_get_nd(): don't unlock parent too early	2019-11-10 11:56:55 -05:00
auditfilter.c	audit: fix error handling in audit_data_to_entry()	2020-02-22 20:36:47 -05:00
auditsc.c	Revert "bpf: Emit audit messages upon successful prog load and unload"	2019-11-23 09:56:02 -08:00
backtracetest.c	…
bounds.c	…
capability.c	…
compat.c	y2038: remove unused time32 interfaces	2020-02-21 11:22:15 -08:00
configs.c	proc: convert everything to "struct proc_ops"	2020-02-04 03:05:26 +00:00
context_tracking.c	context_tracking: Rename context_tracking_is_enabled() => context_tracking_enabled()	2019-10-29 10:01:12 +01:00
cpu.c	Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2020-01-28 10:07:09 -08:00
cpu_pm.c	…
crash_core.c	…
crash_dump.c	…
cred.c	Merge branch 'dhowells' (patches from DavidH)	2020-01-14 09:56:31 -08:00
delayacct.c	…
dma.c	…
elfcore.c	…
exec_domain.c	…
exit.c	for-linus-2020-01-03	2020-01-03 11:17:14 -08:00
extable.c	bpf: Allow to resolve bpf trampoline and dispatcher in unwind	2020-01-25 07:12:40 -08:00
fail_function.c	…
fork.c	hmm related patches for 5.6	2020-01-29 19:56:50 -08:00
freezer.c	…
futex.c	futex: Fix kernel-doc notation warning	2020-01-09 13:23:40 +01:00
gen_kheaders.sh	kheaders: explain why include/config/autoconf.h is excluded from md5sum	2019-11-11 20:10:01 +09:00
groups.c	…
hung_task.c	…
iomem.c	…
irq_work.c	irq_work: Fix IRQ_WORK_BUSY bit clearing	2019-11-15 10:48:37 +01:00
jump_label.c	…
kallsyms.c	Kbuild updates for v5.6 (2nd)	2020-02-09 16:05:50 -08:00
kcmp.c	…
kcov.c	kcov: remote coverage support	2019-12-04 19:44:14 -08:00
kexec.c	kexec: add machine_kexec_post_load()	2020-01-08 16:32:55 +00:00
kexec_core.c	kexec: add machine_kexec_post_load()	2020-01-08 16:32:55 +00:00
kexec_elf.c	…
kexec_file.c	kexec: add machine_kexec_post_load()	2020-01-08 16:32:55 +00:00
kexec_internal.h	kexec: add machine_kexec_post_load()	2020-01-08 16:32:55 +00:00
kheaders.c	…
kmod.c	…
kprobes.c	kprobes: Fix optimize_kprobe()/unoptimize_kprobe() cancellation logic	2020-01-09 12:40:13 +01:00
ksysfs.c	…
kthread.c	…
latencytop.c	proc: convert everything to "struct proc_ops"	2020-02-04 03:05:26 +00:00
module-internal.h	…
module.c	proc: convert everything to "struct proc_ops"	2020-02-04 03:05:26 +00:00
module_signature.c	…
module_signing.c	…
notifier.c	kernel/notifier.c: remove blocking_notifier_chain_cond_register()	2019-12-04 19:44:12 -08:00
nsproxy.c	ns: Introduce Time Namespace	2020-01-14 12:20:48 +01:00
padata.c	padata: update documentation	2019-12-11 16:37:02 +08:00
panic.c	locking/refcount: Remove unused 'refcount_error_report()' function	2019-11-25 09:15:42 +01:00
params.c	…
pid.c	pid: Implement pidfd_getfd syscall	2020-01-13 21:49:36 +01:00
pid_namespace.c	fork: extend clone3() to support setting a PID	2019-11-15 23:49:22 +01:00
profile.c	proc: convert everything to "struct proc_ops"	2020-02-04 03:05:26 +00:00
ptrace.c	ptrace: reintroduce usage of subjective credentials in ptrace_has_cap()	2020-01-18 13:51:39 +01:00
range.c	…
reboot.c	…
relay.c	…
resource.c	…
rseq.c	rseq: Reject unknown flags on rseq unregister	2019-12-25 10:41:20 +01:00
seccomp.c	bpf: Use bpf_prog_run_pin_on_cpu() at simple call sites.	2020-02-24 16:20:09 -08:00
signal.c	signal: avoid double atomic counter increments for user accounting	2020-02-26 09:54:03 -08:00
smp.c	smp: Remove superfluous cond_func check in smp_call_function_many_cond()	2020-01-28 15:43:00 +01:00
smpboot.c	…
smpboot.h	…
softirq.c	…
stackleak.c	…
stacktrace.c	stacktrace: Get rid of unneeded '!!' pattern	2019-11-11 10:30:59 +01:00
stop_machine.c	stop_machine: Make stop_cpus() static	2020-01-17 10:19:21 +01:00
sys.c	prctl: PR_{G,S}ET_IO_FLUSHER to support controlling memory reclaim	2020-01-28 10:09:51 +01:00
sys_ni.c	y2038: allow disabling time32 system calls	2019-11-15 14:38:30 +01:00
sysctl-test.c	kunit: allow kunit tests to be loaded as a module	2020-01-09 16:42:29 -07:00
sysctl.c	s390: remove obsolete ieee_emulation_warnings	2020-02-19 13:51:46 +01:00
sysctl_binary.c	sysctl: Remove the sysctl system call	2019-11-26 13:03:56 -06:00
task_work.c	…
taskstats.c	taskstats: fix data-race	2019-12-04 15:18:39 +01:00
test_kprobes.c	…
torture.c	…
tracepoint.c	…
tsacct.c	tsacct: add 64-bit btime field	2019-12-18 18:07:31 +01:00
ucount.c	…
uid16.c	…
uid16.h	…
umh.c	…
up.c	smp/up: Make smp_call_function_single() match SMP semantics	2020-02-07 15:34:12 +01:00
user-return-notifier.c	…
user.c	…
user_namespace.c	…
utsname.c	…
utsname_sysctl.c	…
watchdog.c	watchdog/softlockup: Enforce that timestamp is valid on boot	2020-01-17 11:19:22 +01:00
watchdog_hld.c	…
workqueue.c	Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2020-01-28 10:07:09 -08:00
workqueue_internal.h	…