Re: [RFC][PATCH 2/2 v3] security: Add task_settimerslack/task_gettimerslack LSM hook

From: James Morris
Date: Thu Jul 21 2016 - 07:44:07 EST

On Wed, 20 Jul 2016, John Stultz wrote:

> On Tue, Jul 19, 2016 at 11:12 PM, James Morris <jmorris@xxxxxxxxx> 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