Re: [RFC 0/5] perf: Per PMU access controls (paranoid setting)

[Andi Kleen <ak@linux.intel.com>]

> There's also been prior discussion on these feature in other contexts
> (e.g. android expoits resulting from out-of-tree drivers). It would be
> nice to see those considered.
> 
> IIRC The conclusion from prior discussions (e.g. [1]) was that we wanted
> finer granularity of control such that we could limit PMU access to
> specific users -- e.g. disallow arbitrary android apps from poking *any*
> PMU, while allowing some more trusted apps/users to uses *some* specific
> PMUs.
> 
> e.g. we could add /sys/bus/event_source/devices/${PMU}/device, protect
> this via the usual fs ACLs, and pass the fd to perf_event_open()
> somehow. A valid fd would act as a capability, taking precedence over
> perf_event_paranoid.

That sounds like an orthogonal feature. I don't think the original
patchkit would need to be hold up for this. It would be something
in addition.

BTW can't you already do that with the syscall filter? I assume
the Android sandboxes already use that. Just forbid perf_event_open
for the apps.

-Andi