From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 39A0228E00 for ; Wed, 20 Sep 2023 11:53:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B4B75C433C8; Wed, 20 Sep 2023 11:53:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1695210823; bh=BzbVTHA+YUQpO8lAXZUkr1xXC3dGlrsfZLrOcKutGCY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=C3LtxUTRP8Uh6NCWFYnCKl2bsd6oH1ALq83ABZui7GUO1JvWduroSKfRSQMglO+7I apm0zipEI/00Ya+ZaOvaBpa6a5GtcuGUVhjOhTnXB+b8jtOgJnRwJuuFjgJh/Q0C3D Uyq9Kg9Je+rv142lXNy3uST92GRyErFkcpagWhyY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Adam Williamson , Ondrej Mosnacek , Jeff Layton , Paul Moore Subject: [PATCH 6.5 191/211] selinux: fix handling of empty opts in selinux_fs_context_submount() Date: Wed, 20 Sep 2023 13:30:35 +0200 Message-ID: <20230920112851.793889567@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230920112845.859868994@linuxfoundation.org> References: <20230920112845.859868994@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ondrej Mosnacek commit ccf1dab96be4caed7c5235b1cfdb606ac161b996 upstream. selinux_set_mnt_opts() relies on the fact that the mount options pointer is always NULL when all options are unset (specifically in its !selinux_initialized() branch. However, the new selinux_fs_context_submount() hook breaks this rule by allocating a new structure even if no options are set. That causes any submount created before a SELinux policy is loaded to be rejected in selinux_set_mnt_opts(). Fix this by making selinux_fs_context_submount() leave fc->security set to NULL when there are no options to be copied from the reference superblock. Cc: Reported-by: Adam Williamson Link: https://bugzilla.redhat.com/show_bug.cgi?id=2236345 Fixes: d80a8f1b58c2 ("vfs, security: Fix automount superblock LSM init problem, preventing NFS sb sharing") Signed-off-by: Ondrej Mosnacek Reviewed-by: Jeff Layton Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman --- security/selinux/hooks.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2748,14 +2748,20 @@ static int selinux_umount(struct vfsmoun static int selinux_fs_context_submount(struct fs_context *fc, struct super_block *reference) { - const struct superblock_security_struct *sbsec; + const struct superblock_security_struct *sbsec = selinux_superblock(reference); struct selinux_mnt_opts *opts; + /* + * Ensure that fc->security remains NULL when no options are set + * as expected by selinux_set_mnt_opts(). + */ + if (!(sbsec->flags & (FSCONTEXT_MNT|CONTEXT_MNT|DEFCONTEXT_MNT))) + return 0; + opts = kzalloc(sizeof(*opts), GFP_KERNEL); if (!opts) return -ENOMEM; - sbsec = selinux_superblock(reference); if (sbsec->flags & FSCONTEXT_MNT) opts->fscontext_sid = sbsec->sid; if (sbsec->flags & CONTEXT_MNT)