linux-kernel - Re: [PATCH] ipc: don't audit capability check in ipc

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Message-ID: <CAHC9VhQYLJVweDgBkRo=0_kS1TAUQH_YfT+woSfBW0SjUO4nqg@mail.gmail.com>
Date: Mon, 26 Jan 2026 17:50:12 -0500
From: Paul Moore <paul@...l-moore.com>
To: Ondrej Mosnacek <omosnace@...hat.com>, Serge Hallyn <serge@...lyn.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, "Eric W . Biederman" <ebiederm@...ssion.com>, 
	Alexey Gladkov <legion@...nel.org>, linux-kernel@...r.kernel.org, 
	linux-security-module@...r.kernel.org, selinux@...r.kernel.org
Subject: Re: [PATCH] ipc: don't audit capability check in ipc_permissions()

On Thu, Jan 22, 2026 at 9:56 AM Ondrej Mosnacek <omosnace@...hat.com> wrote:
>
> The IPC sysctls implement the ctl_table_root::permissions hook and
> they override the file access mode based on the CAP_CHECKPOINT_RESTORE
> capability, which is being checked regardless of whether any access is
> actually denied or not, so if an LSM denies the capability, an audit
> record may be logged even when access is in fact granted.
>
> It wouldn't be viable to restructure the sysctl permission logic to only
> check the capability when the access would be actually denied if it's
> not granted. Thus, do the same as in net_ctl_permissions()
> (net/sysctl_net.c) - switch from ns_capable() to ns_capable_noaudit(),
> so that the check never emits an audit record.
>
> Fixes: 0889f44e2810 ("ipc: Check permissions for checkpoint_restart sysctls at open time")
> Signed-off-by: Ondrej Mosnacek <omosnace@...hat.com>
> ---
>  include/linux/capability.h | 6 ++++++
>  ipc/ipc_sysctl.c           | 2 +-
>  2 files changed, 7 insertions(+), 1 deletion(-)

This change seems reasonable to me, but I would make sure Serge has a
chance to review/ACK this patch as it has a capability impact.

-- 
paul-moore.com