Re: [PATCH v2 3/3] cgroup: implement "nsdelegate" mount option

[Tejun Heo]

On Tue, Jun 27, 2017 at 02:30:28PM -0400, Tejun Heo wrote:
> Currently, cgroup only supports delegation to !root users and cgroup
> namespaces don't get any special treatments.  This limits the
> usefulness of cgroup namespaces as they by themselves can't be safe
> delegation boundaries.  A process inside a cgroup can change the
> resource control knobs of the parent in the namespace root and may
> move processes in and out of the namespace if cgroups outside its
> namespace are visible somehow.
> 
> This patch adds a new mount option "nsdelegate" which makes cgroup
> namespaces delegation boundaries.  If set, cgroup behaves as if write
> permission based delegation took place at namespace boundaries -
> writes to the resource control knobs from the namespace root are
> denied and migration crossing the namespace boundary aren't allowed
> from inside the namespace.
> 
> This allows cgroup namespace to function as a delegation boundary by
> itself.
> 
> v2: Silently ignore nsdelegate specified on !init mounts.
> 
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Aravind Anbudurai <aru7@xxxxxx>
> Cc: Serge Hallyn <serge@xxxxxxxxxx>
> Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>

Applying 2-3 to cgroup/for-4.13.

Thanks.

-- 
tejun