Re: [kernel-hardening] [PATCH 1/2] security, perf: allow further restriction of perf_event_open

From: Arnaldo Carvalho de Melo
Date: Wed Oct 19 2016 - 11:11:52 EST

Em Wed, Oct 19, 2016 at 12:01:26PM +0200, Peter Zijlstra escreveu:
> On Tue, Oct 18, 2016 at 05:15:01PM -0400, Daniel Micay wrote:
> > It's also worth noting that fine-grained control via a scoped mechanism
> > would likely only be used to implement *more restrictions* on Android,
> > not to make the feature less aggressive.

> > It's desirable for perf events to be disabled by default for non-root
> > across the board on Android.

> Right, but this is Android. The knob seems to now also live in Debian
> (and derived) distros. And there it is utter crap.

> It completely defeats having perf for a fairly large segment of
> corporate developers who do not get to have root on their own machines
> (which is stupid policy but whatever).

> It similarly defeats development of self profiling JITs and whatnot.

> A capability would allow people to run perf (or another sanctioned
> binary), even though in general they cannot do sys_perf_event_open().

But self profiling JITs would be useful for non-developers, on Android
(anywhere, really), and for that it would require being able to at
least, well, self profile, using sys_perf_event_open() by a normal
process, limited to profiling itself, no?

This not being possible, self profiling will use some other means, its
like sys_perf_event_open() never existed for them.

- Arnaldo