On Thu, Mar 10, 2016 at 08:25:02AM +0100, Jiri Olsa wrote:
> On Thu, Mar 10, 2016 at 09:36:37AM +0900, Namhyung Kim wrote:
> > Hi Jiri,
> >
> > On Wed, Mar 09, 2016 at 09:46:41PM +0100, Jiri Olsa wrote:
> > > Currently we check sample type for ftrace:function event
> > > even if it's not created as sampling event. That prevents
> > > creating ftrace_function event in counting mode.
> > >
> > > Making sure we check sample types only for sampling events.
> > >
> > > Before:
> > > $ sudo perf stat -e ftrace:function ls
> > > ...
> > >
> > > Performance counter stats for 'ls':
> > >
> > > <not supported> ftrace:function
> > >
> > > 0.001983662 seconds time elapsed
> > >
> > > After:
> > > $ sudo perf stat -e ftrace:function ls
> > > ...
> > >
> > > Performance counter stats for 'ls':
> > >
> > > 44,498 ftrace:function
> > >
> > > 0.037534722 seconds time elapsed
> > >
> > > Signed-off-by: Jiri Olsa <[email protected]>
> > > ---
> > > kernel/trace/trace_event_perf.c | 4 ++--
> > > 1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/kernel/trace/trace_event_perf.c
> > > b/kernel/trace/trace_event_perf.c
> > > index 00df25fd86ef..a7171ec2c1ca 100644
> > > --- a/kernel/trace/trace_event_perf.c
> > > +++ b/kernel/trace/trace_event_perf.c
> > > @@ -52,14 +52,14 @@ static int perf_trace_event_perm(struct
> > > trace_event_call *tp_event,
> > > * event, due to issues with page faults while tracing page
> > > * fault handler and its overall trickiness nature.
> > > */
> > > - if (!p_event->attr.exclude_callchain_user)
> > > + if (is_sampling_event(p_event) &&
> > > !p_event->attr.exclude_callchain_user)
> > > return -EINVAL;
> > >
> > > /*
> > > * Same reason to disable user stack dump as for user space
> > > * callchains above.
> > > */
> > > - if (p_event->attr.sample_type & PERF_SAMPLE_STACK_USER)
> > > + if (is_sampling_event(p_event) && p_event->attr.sample_type &
> > > PERF_SAMPLE_STACK_USER)
> > > return -EINVAL;
> > > }
> > >
> >
> > What about checking is_sampling_event() first and goto the last
> > paranoid_tracepoint_raw check instead? This way we can remove the
> > same check in the function trace case.
>
> right, will check
hum, did you mean something like this?
I'd rather keep it the original way.. seems more straight
jirka
---
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 00df25fd86ef..7c1edb57c823 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -44,23 +44,22 @@ static int perf_trace_event_perm(struct trace_event_call
*tp_event,
/* The ftrace function trace is allowed only for root. */
if (ftrace_event_is_function(tp_event)) {
- if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
- return -EPERM;
-
/*
* We don't allow user space callchains for function trace
* event, due to issues with page faults while tracing page
* fault handler and its overall trickiness nature.
*/
- if (!p_event->attr.exclude_callchain_user)
+ if (is_sampling_event(p_event) &&
!p_event->attr.exclude_callchain_user)
return -EINVAL;
/*
* Same reason to disable user stack dump as for user space
* callchains above.
*/
- if (p_event->attr.sample_type & PERF_SAMPLE_STACK_USER)
+ if (is_sampling_event(p_event) && p_event->attr.sample_type &
PERF_SAMPLE_STACK_USER)
return -EINVAL;
+
+ goto root_check;
}
/* No tracing, just counting, so no obvious leak */
@@ -73,6 +72,7 @@ static int perf_trace_event_perm(struct trace_event_call
*tp_event,
return 0;
}
+root_check:
/*
* ...otherwise raw tracepoint data can be a severe data leak,
* only allow root to have these.
