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

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Message-ID: <CAHC9VhSLi2-TBUyayML+tAuC+XF7jCAAL48oCB4qQqTrGXcMyA@mail.gmail.com>
Date: Tue, 27 Jan 2026 17:06:47 -0500
From: Paul Moore <paul@...l-moore.com>
To: "Serge E. Hallyn" <serge@...lyn.com>
Cc: Ondrej Mosnacek <omosnace@...hat.com>, 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 Mon, Jan 26, 2026 at 9:01 PM Serge E. Hallyn <serge@...lyn.com> wrote:
> On Mon, Jan 26, 2026 at 05:50:12PM -0500, Paul Moore wrote:
> > 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.
>
> Acked-by: Serge Hallyn <serge@...lyn.com>
>
> Thanks - looks good to me.

I don't see a dedicated IPC maintainer/tree, do you want to take this
via the capabilities tree Serge?

-- 
paul-moore.com