netdev - Re: [PATCH v2 1/5] lsm: Add hook unix_path

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Message-ID: <20260115.a6f842555347@gnoack.org>
Date: Thu, 15 Jan 2026 23:32:21 +0100
From: Günther Noack <gnoack3000@...il.com>
To: Demi Marie Obenour <demiobenour@...il.com>
Cc: Paul Moore <paul@...l-moore.com>,
	Christian Brauner <brauner@...nel.org>,
	Justin Suess <utilityemal77@...il.com>,
	Mickaël Salaün <mic@...ikod.net>,
	James Morris <jmorris@...ei.org>,
	"Serge E . Hallyn" <serge@...lyn.com>,
	linux-security-module@...r.kernel.org, Tingmao Wang <m@...wtm.org>,
	Samasth Norway Ananda <samasth.norway.ananda@...cle.com>,
	Matthieu Buffet <matthieu@...fet.re>,
	Mikhail Ivanov <ivanov.mikhail1@...wei-partners.com>,
	konstantin.meskhidze@...wei.com, Alyssa Ross <hi@...ssa.is>,
	Jann Horn <jannh@...gle.com>,
	Tahera Fahimi <fahimitahera@...il.com>,
	Simon Horman <horms@...nel.org>, netdev@...r.kernel.org,
	Alexander Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH v2 1/5] lsm: Add hook unix_path_connect

On Thu, Jan 15, 2026 at 04:24:48PM -0500, Demi Marie Obenour wrote:
> On 1/15/26 05:10, Günther Noack wrote:
> >   I would prefer if the correctness of our LSM did not depend on
> >   keeping track of the error scenarios in af_unix.c.  This seems
> >   brittle.
> 
> Indeed so.

Thanks for the support!

> > Overall, I am not convinced that using pre-existing hooks is the right
> > way and I would prefer the approach where we have a more dedicated LSM
> > hook for the path lookup.
> > 
> > Does that seem reasonable?  Let me know what you think.
> > 
> > –Günther
> 
> Having a dedicated LSM hook for all path lookups is definitely my
> preferred approach.  Could this allow limiting directory traversal
> as well?

No, this does not limit all path lookups, in the sense of what was
discussed in the thread at [1]. (I assume this is what you meant?)

The LSM hook proposed here is only about the lookup of named UNIX
domain sockets, as it happens when clients pass a struct sockaddr_un
to connect(2) or sendmsg(2).

–Günther

[1] https://lore.kernel.org/all/81f908e3-8a98-46e7-b20c-fe647784ceb4@gmail.com/