Date: Tue, 13 Dec 2016 13:47:03 -0500
From: Tejun Heo <tj@kernel.org>
To: Casey Schaufler <casey@schaufler-ca.com>
Cc: John Stultz <john.stultz@linaro.org>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        lkml <linux-kernel@vger.kernel.org>, Li Zefan <lizefan@huawei.com>,
        Jonathan Corbet <corbet@lwn.net>,
        "open list:CONTROL GROUP (CGROUP)" <cgroups@vger.kernel.org>,
        Android Kernel Team <kernel-team@android.com>,
        Rom Lemarchand <romlem@android.com>, Colin Cross <ccross@android.com>,
        Dmitry Shmidt <dimitrysh@google.com>, Todd Kjos <tkjos@google.com>,
        Christian Poetzsch <christian.potzsch@imgtec.com>,
        Amit Pundir <amit.pundir@linaro.org>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Kees Cook <keescook@chromium.org>,
        "Serge E . Hallyn" <serge@hallyn.com>,
        Andy Lutomirski <luto@amacapital.net>,
        Linux API <linux-api@vger.kernel.org>
Subject: Re: [PATCH v5] cgroup: Add new capability to allow a process to
 migrate other tasks between cgroups
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Hello, Casey.

On Tue, Dec 13, 2016 at 10:32:14AM -0800, Casey Schaufler wrote:
> > The trouble is that CAP_SYS_NICE or _RESOURCE (which was tried in an
> > earlier version of this patch) aren't necessarily appropriate for
> > non-android systems. See Andy's objection here:
> > https://lkml.org/lkml/2016/11/8/946
> 
> Then we need to see what those as-yet-unimplemented systems
> require and how to address them. I don't think that taking
> the "someone might want it" approach is really appropriate.

I understands that there can be reservations regarding adding a new
CAP but this isn't about someone possibly wanting it in the future.
It's more about overloading existing CAPs leading to permitting
unintended operations.  e.g. ppl who've been delegating
CAP_SYS_RESOURCES would automatically end up delegating cgroup
organization without intending so.  Using an existing cap would have
been nice but it just doesn't look like we have a good one to
overload.

Thanks.

-- 
tejun