| Message ID | 20241127111020.1738105-1-elver@google.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [bpf-next,v2,1/2] bpf: Remove bpf_probe_write_user() warning message | expand |
On Wed, Nov 27, 2024 at 12:10:00PM +0100, Marco Elver wrote: > The warning message for bpf_probe_write_user() was introduced in > 96ae52279594 ("bpf: Add bpf_probe_write_user BPF helper to be called in > tracers"), with the following in the commit message: > > Given this feature is meant for experiments, and it has a risk of > crashing the system, and running programs, we print a warning on > when a proglet that attempts to use this helper is installed, > along with the pid and process name. > > After 8 years since 96ae52279594, bpf_probe_write_user() has found > successful applications beyond experiments [1, 2], with no other good > alternatives. Despite its intended purpose for "experiments", that > doesn't stop Hyrum's law, and there are likely many more users depending > on this helper: "[..] it does not matter what you promise [..] all > observable behaviors of your system will be depended on by somebody." > > The ominous "helper that may corrupt user memory!" has offered no real > benefit, and has been found to lead to confusion where the system > administrator is loading programs with valid use cases. > > As such, remove the warning message. > > Link: https://lore.kernel.org/lkml/20240404190146.1898103-1-elver@google.com/ [1] > Link: https://lore.kernel.org/r/lkml/CAAn3qOUMD81-vxLLfep0H6rRd74ho2VaekdL4HjKq+Y1t9KdXQ@mail.gmail.com/ [2] > Link: https://lore.kernel.org/all/CAEf4Bzb4D_=zuJrg3PawMOW3KqF8JvJm9SwF81_XHR2+u5hkUg@mail.gmail.com/ > Signed-off-by: Marco Elver <elver@google.com> Acked-by: Jiri Olsa <jolsa@kernel.org> jirka > --- > v2: > * Just delete the message entirely (suggested by Andrii Nakryiko) > --- > kernel/trace/bpf_trace.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index 630b763e5240..0ab56af2e298 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -362,9 +362,6 @@ 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; > } > > -- > 2.47.0.338.g60cca15819-goog >
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 630b763e5240..0ab56af2e298 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -362,9 +362,6 @@ 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; }
The warning message for bpf_probe_write_user() was introduced in 96ae52279594 ("bpf: Add bpf_probe_write_user BPF helper to be called in tracers"), with the following in the commit message: Given this feature is meant for experiments, and it has a risk of crashing the system, and running programs, we print a warning on when a proglet that attempts to use this helper is installed, along with the pid and process name. After 8 years since 96ae52279594, bpf_probe_write_user() has found successful applications beyond experiments [1, 2], with no other good alternatives. Despite its intended purpose for "experiments", that doesn't stop Hyrum's law, and there are likely many more users depending on this helper: "[..] it does not matter what you promise [..] all observable behaviors of your system will be depended on by somebody." The ominous "helper that may corrupt user memory!" has offered no real benefit, and has been found to lead to confusion where the system administrator is loading programs with valid use cases. As such, remove the warning message. Link: https://lore.kernel.org/lkml/20240404190146.1898103-1-elver@google.com/ [1] Link: https://lore.kernel.org/r/lkml/CAAn3qOUMD81-vxLLfep0H6rRd74ho2VaekdL4HjKq+Y1t9KdXQ@mail.gmail.com/ [2] Link: https://lore.kernel.org/all/CAEf4Bzb4D_=zuJrg3PawMOW3KqF8JvJm9SwF81_XHR2+u5hkUg@mail.gmail.com/ Signed-off-by: Marco Elver <elver@google.com> --- v2: * Just delete the message entirely (suggested by Andrii Nakryiko) --- kernel/trace/bpf_trace.c | 3 --- 1 file changed, 3 deletions(-)