From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-1909.mail.infomaniak.ch (smtp-1909.mail.infomaniak.ch [185.125.25.9]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D86C038F92F for ; Tue, 17 Mar 2026 21:14:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.125.25.9 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773782077; cv=none; b=qtsq7ifIUC4FYXy8IGTgCqbh8a2XEX5s7UvsmpsdFm6iFACmb4xhkCO2b/pv7+FAZhl2d0xOpiGNdfmVvPm5dg2K3BQwzjhs4oR3MUlO6z1EwvGdEO/CKlAkPNKjt836hEcCw/UCtH6ucokG3Yk0ujmhTYhdnzMUbX4Q7U+qOag= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773782077; c=relaxed/simple; bh=TGqDQVKenKst7ulkB8U2FPYOSqBdO6CBrwx/TU5vxvw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=A22AFl+R5YYK0yDCqgC7sZ6HG65CCIFELh2wfaRKiSIGtB2OS6ilB4RpynekpTyQKzsigqgPHBngnbPkW7xbQ8vhcFhGrd8W74/enrhj7UyD3ZW6AbAFBQ2oL3zVie1N+R4hYDpUcY1cR1ndvTHJxkHuUAdorzKExf7ClMX4HKg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=digikod.net; spf=pass smtp.mailfrom=digikod.net; dkim=pass (1024-bit key) header.d=digikod.net header.i=@digikod.net header.b=AE2sstpk; arc=none smtp.client-ip=185.125.25.9 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=digikod.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=digikod.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=digikod.net header.i=@digikod.net header.b="AE2sstpk" Received: from smtp-4-0000.mail.infomaniak.ch (smtp-4-0000.mail.infomaniak.ch [10.7.10.107]) by smtp-4-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4fb4TZ5w39z2RS; Tue, 17 Mar 2026 22:14:26 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=digikod.net; s=20191114; t=1773782066; bh=9PdX0GoF+dwhSnTxhQP6xSC/aUKyJh+SmOgu8OgcULE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=AE2sstpkYihXXRJ/A5ZQNWjOTKCFVk/U3E+sNDnugqB1XY1KLhpwj6DB+YKpZm43l 2PUNziPG4SeM6bTGMhuqudDTn550ikIdgTwjMwQCCVG2dhoL35gIOWSslx6MMVyy42 PyHcbAeO7Ou4BrIZJZDn4pYyIJKvj2g8qNWW0tTs= Received: from unknown by smtp-4-0000.mail.infomaniak.ch (Postfix) with ESMTPA id 4fb4TY2dTNzrFg; Tue, 17 Mar 2026 22:14:25 +0100 (CET) Date: Tue, 17 Mar 2026 22:14:23 +0100 From: =?utf-8?Q?Micka=C3=ABl_Sala=C3=BCn?= To: Paul Moore , Sebastian Andrzej Siewior , Kuniyuki Iwashima , Simon Horman , Jakub Kicinski , netdev@vger.kernel.org Cc: =?utf-8?Q?G=C3=BCnther?= Noack , John Johansen , James Morris , "Serge E . Hallyn" , Tingmao Wang , Justin Suess , linux-security-module@vger.kernel.org, Samasth Norway Ananda , Matthieu Buffet , Mikhail Ivanov , konstantin.meskhidze@huawei.com, Demi Marie Obenour , Alyssa Ross , Jann Horn , Tahera Fahimi , Alexander Viro , Christian Brauner Subject: Re: [PATCH v6 1/9] lsm: Add LSM hook security_unix_find Message-ID: <20260317.Re1jaiThoo5i@digikod.net> References: <20260315222150.121952-1-gnoack3000@gmail.com> <20260315222150.121952-2-gnoack3000@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260315222150.121952-2-gnoack3000@gmail.com> X-Infomaniak-Routing: alpha Paul and netdev folks, I think this new hook is now good. I'd like to push this series to -next this week. Please let us know if you find any issue, otherwise I guess we'll get more eyes and bots in the -next tree. On Sun, Mar 15, 2026 at 11:21:42PM +0100, Günther Noack wrote: > From: Justin Suess > > Add a LSM hook security_unix_find. > > This hook is called to check the path of a named unix socket before a > connection is initiated. The peer socket may be inspected as well. > > Why existing hooks are unsuitable: > > Existing socket hooks, security_unix_stream_connect(), > security_unix_may_send(), and security_socket_connect() don't provide > TOCTOU-free / namespace independent access to the paths of sockets. > > (1) We cannot resolve the path from the struct sockaddr in existing hooks. > This requires another path lookup. A change in the path between the > two lookups will cause a TOCTOU bug. > > (2) We cannot use the struct path from the listening socket, because it > may be bound to a path in a different namespace than the caller, > resulting in a path that cannot be referenced at policy creation time. > > Cc: Günther Noack > Cc: Tingmao Wang > Signed-off-by: Justin Suess > --- > include/linux/lsm_hook_defs.h | 5 +++++ > include/linux/security.h | 11 +++++++++++ > net/unix/af_unix.c | 13 ++++++++++--- > security/security.c | 20 ++++++++++++++++++++ > 4 files changed, 46 insertions(+), 3 deletions(-) > > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h > index 8c42b4bde09c..7a0fd3dbfa29 100644 > --- a/include/linux/lsm_hook_defs.h > +++ b/include/linux/lsm_hook_defs.h > @@ -317,6 +317,11 @@ LSM_HOOK(int, 0, post_notification, const struct cred *w_cred, > LSM_HOOK(int, 0, watch_key, struct key *key) > #endif /* CONFIG_SECURITY && CONFIG_KEY_NOTIFICATIONS */ > > +#if defined(CONFIG_SECURITY_NETWORK) && defined(CONFIG_SECURITY_PATH) > +LSM_HOOK(int, 0, unix_find, const struct path *path, struct sock *other, > + int flags) > +#endif /* CONFIG_SECURITY_NETWORK && CONFIG_SECURITY_PATH */ > + > #ifdef CONFIG_SECURITY_NETWORK > LSM_HOOK(int, 0, unix_stream_connect, struct sock *sock, struct sock *other, > struct sock *newsk) > diff --git a/include/linux/security.h b/include/linux/security.h > index 83a646d72f6f..99a33d8eb28d 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -1931,6 +1931,17 @@ static inline int security_mptcp_add_subflow(struct sock *sk, struct sock *ssk) > } > #endif /* CONFIG_SECURITY_NETWORK */ > > +#if defined(CONFIG_SECURITY_NETWORK) && defined(CONFIG_SECURITY_PATH) > + > +int security_unix_find(const struct path *path, struct sock *other, int flags); > + > +#else /* CONFIG_SECURITY_NETWORK && CONFIG_SECURITY_PATH */ > +static inline int security_unix_find(const struct path *path, struct sock *other, int flags) > +{ > + return 0; > +} > +#endif /* CONFIG_SECURITY_NETWORK && CONFIG_SECURITY_PATH */ > + > #ifdef CONFIG_SECURITY_INFINIBAND > int security_ib_pkey_access(void *sec, u64 subnet_prefix, u16 pkey); > int security_ib_endport_manage_subnet(void *sec, const char *name, u8 port_num); > diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c > index 3756a93dc63a..aced28179bac 100644 > --- a/net/unix/af_unix.c > +++ b/net/unix/af_unix.c > @@ -1231,11 +1231,18 @@ static struct sock *unix_find_bsd(struct sockaddr_un *sunaddr, int addr_len, > goto path_put; > > err = -EPROTOTYPE; > - if (sk->sk_type == type) > - touch_atime(&path); > - else > + if (sk->sk_type != type) > goto sock_put; > > + /* > + * We call the hook because we know that the inode is a socket and we > + * hold a valid reference to it via the path. > + */ > + err = security_unix_find(&path, sk, flags); > + if (err) > + goto sock_put; > + touch_atime(&path); > + > path_put(&path); > > return sk; > diff --git a/security/security.c b/security/security.c > index 67af9228c4e9..c73196b8db4b 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -4731,6 +4731,26 @@ int security_mptcp_add_subflow(struct sock *sk, struct sock *ssk) > > #endif /* CONFIG_SECURITY_NETWORK */ > > +#if defined(CONFIG_SECURITY_NETWORK) && defined(CONFIG_SECURITY_PATH) > +/** > + * security_unix_find() - Check if a named AF_UNIX socket can connect > + * @path: path of the socket being connected to > + * @other: peer sock > + * @flags: flags associated with the socket > + * > + * This hook is called to check permissions before connecting to a named > + * AF_UNIX socket. > + * > + * Return: Returns 0 if permission is granted. > + */ > +int security_unix_find(const struct path *path, struct sock *other, int flags) > +{ > + return call_int_hook(unix_find, path, other, flags); > +} > +EXPORT_SYMBOL(security_unix_find); > + > +#endif /* CONFIG_SECURITY_NETWORK && CONFIG_SECURITY_PATH */ > + > #ifdef CONFIG_SECURITY_INFINIBAND > /** > * security_ib_pkey_access() - Check if access to an IB pkey is allowed > -- > 2.53.0 > >