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

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Message-ID: <20161019100126.GI3102@twins.programming.kicks-ass.net>
Date:   Wed, 19 Oct 2016 12:01:26 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Daniel Micay <danielmicay@...il.com>
Cc:     kernel-hardening@...ts.openwall.com,
        Mark Rutland <mark.rutland@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Jeff Vander Stoep <jeffv@...gle.com>
Subject: Re: [kernel-hardening] [PATCH 1/2] security, perf: allow further
 restriction of perf_event_open

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().