Re: [PATCH] cgroup-v1: Correct privileges check in release_agent writes

On Thu, Feb 17, 2022 at 05:11:28PM +0100, Michal Koutný wrote:

The idea is to check: a) the owning user_ns of cgroup_ns, b) capabilities in init_user_ns.

The commit 24f600856418 ("cgroup-v1: Require capabilities to set release_agent") got this wrong in the write handler of release_agent since it checked user_ns of the opener (may be different from the owning user_ns of cgroup_ns). Secondly, to avoid possibly confused deputy, the capability of the opener must be checked.

Fixes: 24f600856418 ("cgroup-v1: Require capabilities to set release_agent") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/stable/20220216121142.GB30035@blackbody.suse.cz/ Signed-off-by: Michal Koutný mkoutny@suse.com

Applied to cgroup/for-5.17-fixes.

Thanks.