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Date: Tue, 30 Aug 2016 16:06:06 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Kees Cook <keescook@chromium.org>
Cc: John Stultz <john.stultz@linaro.org>,
        lkml <linux-kernel@vger.kernel.org>,
        "Serge E. Hallyn" <serge@hallyn.com>,
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        Dmitry Shmidt <dimitrysh@google.com>, Elliott Hughes <enh@google.com>,
        Android Kernel Team <kernel-team@android.com>
Subject: Re: [RESEND][PATCH] proc: Fix timerslack_ns CAP_SYS_NICE check when
 adjusting self
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On Tue, 30 Aug 2016 18:46:23 -0400 Kees Cook <keescook@chromium.org> wrote:

> On Mon, Aug 22, 2016 at 7:01 PM, John Stultz <john.stultz@linaro.org> wrote:
> > In changing from checking ptrace_may_access(p, PTRACE_MODE_ATTACH_FSCREDS)
> > to capable(CAP_SYS_NICE), I missed that ptrace_my_access succeeds
> > when p == current, but the CAP_SYS_NICE doesn't.
> >
> > Thus while the previous commit was intended to loosen the needed
> > privledges to modify a processes timerslack, it needlessly restricted
> > a task modifying its own timerslack via the proc/<tid>/timerslack_ns
> > (which is permitted also via the PR_SET_TIMERSLACK method).
> >
> > This patch corrects this by checking if p == current before checking
> > the CAP_SYS_NICE value.
> >
> > This patch applies on top of my two previous patches currently in -mm
> >
> > Cc: Kees Cook <keescook@chromium.org>
> > Cc: "Serge E. Hallyn" <serge@hallyn.com>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Thomas Gleixner <tglx@linutronix.de>
> > CC: Arjan van de Ven <arjan@linux.intel.com>
> > Cc: Oren Laadan <orenl@cellrox.com>
> > Cc: Ruchi Kandoi <kandoiruchi@google.com>
> > Cc: Rom Lemarchand <romlem@android.com>
> > Cc: Todd Kjos <tkjos@google.com>
> > Cc: Colin Cross <ccross@android.com>
> > Cc: Nick Kralevich <nnk@google.com>
> > Cc: Dmitry Shmidt <dimitrysh@google.com>
> > Cc: Elliott Hughes <enh@google.com>
> > Cc: Android Kernel Team <kernel-team@android.com>
> > Acked-by: Kees Cook <keescook@chromium.org>
> > Signed-off-by: John Stultz <john.stultz@linaro.org>
> 
> Andrew, can you take this for v4.8?

Well, it fixes
proc-relax-proc-tid-timerslack_ns-capability-requirements.patch,
somewhat.  And it textually depends on that.

Do we want all of

proc-relax-proc-tid-timerslack_ns-capability-requirements.patch
proc-add-lsm-hook-checks-to-proc-tid-timerslack_ns.patch
proc-fix-timerslack_ns-cap_sys_nice-check-when-adjusting-self.patch

in 4.8?  If so, why?