From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1752275AbcGULoB (ORCPT <rfc822;w@1wt.eu>);
	Thu, 21 Jul 2016 07:44:01 -0400
Received: from [65.99.196.166] ([65.99.196.166]:43931 "EHLO namei.org"
	rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP
	id S1752139AbcGULnu (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Thu, 21 Jul 2016 07:43:50 -0400
Date: Thu, 21 Jul 2016 21:43:26 +1000 (AEST)
From: James Morris <jmorris@namei.org>
To: John Stultz <john.stultz@linaro.org>
cc: lkml <linux-kernel@vger.kernel.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>,
        LSM List <linux-security-module@vger.kernel.org>,
        SELinux <selinux@tycho.nsa.gov>
Subject: Re: [RFC][PATCH 2/2 v3] security: Add task_settimerslack/task_gettimerslack
 LSM hook
In-Reply-To: <CALAqxLXx3kDWs2SzuEumaqK6=f6=dJYZMRMYA5urHgo7JDtqMg@mail.gmail.com>
Message-ID: <alpine.LRH.2.20.1607212142530.5669@namei.org>
References: <1468872671-9002-1-git-send-email-john.stultz@linaro.org> <1468872671-9002-2-git-send-email-john.stultz@linaro.org> <alpine.LRH.2.20.1607201612020.23817@namei.org> <CALAqxLXx3kDWs2SzuEumaqK6=f6=dJYZMRMYA5urHgo7JDtqMg@mail.gmail.com>
User-Agent: Alpine 2.20 (LRH 67 2015-01-07)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, 20 Jul 2016, John Stultz wrote:

> On Tue, Jul 19, 2016 at 11:12 PM, James Morris <jmorris@namei.org> wrote:
> > On Mon, 18 Jul 2016, John Stultz wrote:
> >
> >> As requested, this patch implements a task_settimerslack and
> >> task_gettimerslack LSM hooks so that the /proc/<tid>/timerslack_ns
> >> interface can have finer grained security policies applied to it.
> >>
> >> I've kept the CAP_SYS_NICE check in the timerslack_ns_write/show
> >> functions, as hiding it in the LSM hook seems too opaque, and doesn't
> >> seem like a widely enough adopted practice.
> >>
> >
> > I may have missed something in the earlier discussion, but why do we need
> > new LSM hooks here vs. calling the existing set/getscheduler hooks?
> 
> Mostly since adding a new hook was suggested originally. I don't think
> there's much difference as it stands, but I guess more fine grained
> checks could be added on the slack amounts, etc.
> 
> I can rework it, so let me know if using the existing hooks would be
> preferred, but otherwise I'll be sending out the non-rfc patches
> tomorrow.


I'd prefer to re-use the existing hooks, unless there is a specific need 
for the extra granularity.


-- 
James Morris
<jmorris@namei.org>