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From: John Stultz <john.stultz@linaro.org>
Date: Mon, 29 Aug 2016 11:28:47 -0700
Message-ID: <CALAqxLX06tFkj7DVrPDJMB3C0-N5jqpFY-J4nS0i+r7GBhGkhw@mail.gmail.com>
Subject: Re: [RESEND][PATCH] proc: Fix timerslack_ns CAP_SYS_NICE check when
 adjusting self
To: lkml <linux-kernel@vger.kernel.org>
Cc: John Stultz <john.stultz@linaro.org>,
        Kees Cook <keescook@chromium.org>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Arjan van de Ven <arjan@linux.intel.com>,
        Oren Laadan <orenl@cellrox.com>, Ruchi Kandoi <kandoiruchi@google.com>,
        Rom Lemarchand <romlem@android.com>, Todd Kjos <tkjos@google.com>,
        Colin Cross <ccross@android.com>, Nick Kralevich <nnk@google.com>,
        Dmitry Shmidt <dimitrysh@google.com>, Elliott Hughes <enh@google.com>,
        Android Kernel Team <kernel-team@android.com>
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On Mon, Aug 22, 2016 at 4:01 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

Ping? Any feedback or comments on this one?

thanks
-john