linux-kernel - Re: [PATCH] cgroup-v1: Correct privileges check in release

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Date:   Tue, 22 Feb 2022 08:13:09 -1000
From:   Tejun Heo <tj@...nel.org>
To:     Michal Koutný <mkoutny@...e.com>
Cc:     "Eric W. Biederman" <ebiederm@...ssion.com>,
        Masami Ichikawa <masami.ichikawa@...ertrust.co.jp>,
        Tabitha Sable <tabitha.c.sable@...il.com>,
        Zefan Li <lizefan.x@...edance.com>,
        Johannes Weiner <hannes@...xchg.org>, stable@...r.kernel.org,
        cgroups@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: 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@...r.kernel.org
> Link: https://lore.kernel.org/stable/20220216121142.GB30035@blackbody.suse.cz/
> Signed-off-by: Michal Koutný <mkoutny@...e.com>

Applied to cgroup/for-5.17-fixes.

Thanks.

-- 
tejun