[Intel-gfx] [PATCH v4 2/9] perf/core: open access for CAP_SYS_PERFMON privileged process

[Peter Zijlstra]

On Thu, Jan 09, 2020 at 02:36:50PM +0300, Alexey Budankov wrote:
> On 08.01.2020 19:07, Peter Zijlstra wrote:
> > On Wed, Dec 18, 2019 at 12:25:35PM +0300, Alexey Budankov wrote:

> >> diff --git a/kernel/events/core.c b/kernel/events/core.c
> >> index 059ee7116008..d9db414f2197 100644
> >> --- a/kernel/events/core.c
> >> +++ b/kernel/events/core.c
> >> @@ -9056,7 +9056,7 @@ static int perf_kprobe_event_init(struct perf_event *event)
> >>  	if (event->attr.type != perf_kprobe.type)
> >>  		return -ENOENT;
> >>  
> >> -	if (!capable(CAP_SYS_ADMIN))
> >> +	if (!perfmon_capable())
> >>  		return -EACCES;
> >>  
> >>  	/*
> > 
> > This one only allows attaching to already extant kprobes, right? It does
> > not allow creation of kprobes.
> 
> This unblocks creation of local trace kprobes and uprobes by CAP_SYS_PERFMON 
> privileged process, exactly the same as for CAP_SYS_ADMIN privileged process.

I've no idea what you just said; it's just words.

Again, this only allows attaching to previously created kprobes, it does
not allow creating kprobes, right?

That is; I don't think CAP_SYS_PERFMON should be allowed to create
kprobes.

As might be clear; I don't actually know what the user-ABI is for
creating kprobes.