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 958431487FA; Thu, 13 Feb 2025 15:05:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739459109; cv=none; b=Nvg+zNbEqDVMjkkXaiOWasqFEb4nkmIaTNYbmg4/1o/8L3w5lwBw8fUyobFOfqTNWMesZFU2Wph8f3ZMORjqLWUUDFsh/g/IfD3ogMg/jbms8S2agPekdP2ImUrdz8AQM9yxaNVyGluiLFGj9j78z0MgJEt4RWIU1JDjbxFnnqk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739459109; c=relaxed/simple; bh=RqW2aCIabCdVje3s7UK/cunJAZgoLEE7LH/UrxslUm0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NkQpYazOh2YiI7x/sW41BU3dZ2T/pq085AZewr6fq29ys3Qz5xvPVcyuxO/hGTAcWFpNUtKcz0u43UMqOZ0/uqBs+ADKPzL04nZahMqZAfviEkbOpItmVgC4WgH4nXfBFO59PCW3ZYPQAk4SXyl5rSU30M+pG4RCLoQryC8xLf4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rwvN0m3S; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="rwvN0m3S" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 02E69C4CED1; Thu, 13 Feb 2025 15:05:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1739459109; bh=RqW2aCIabCdVje3s7UK/cunJAZgoLEE7LH/UrxslUm0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rwvN0m3SVqUt6a9UxBQCnrkdSTFI6u6xnYuWXXFSj7567qNFmsymHeGNTRZpI+0Mo whjjlerVnehPT+rUQYCRELddynaZow5plQ86KsxFplEyNMkiRBVln3mWqw+MQcahqc JSWklfXfzByduW6IbsBNzHXaiGY7wpKgheuwAl8I= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Willem de Bruijn , Ondrej Mosnacek , Stas Sergeev , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.13 138/443] tun: revert fix group permission check Date: Thu, 13 Feb 2025 15:25:03 +0100 Message-ID: <20250213142445.926283539@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250213142440.609878115@linuxfoundation.org> References: <20250213142440.609878115@linuxfoundation.org> User-Agent: quilt/0.68 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 6.13-stable review patch. If anyone has any objections, please let me know. ------------------ From: Willem de Bruijn [ Upstream commit a70c7b3cbc0688016810bb2e0b9b8a0d6a530045 ] This reverts commit 3ca459eaba1bf96a8c7878de84fa8872259a01e3. The blamed commit caused a regression when neither tun->owner nor tun->group is set. This is intended to be allowed, but now requires CAP_NET_ADMIN. Discussion in the referenced thread pointed out that the original issue that prompted this patch can be resolved in userspace. The relaxed access control may also make a device accessible when it previously wasn't, while existing users may depend on it to not be. This is a clean pure git revert, except for fixing the indentation on the gid_valid line that checkpatch correctly flagged. Fixes: 3ca459eaba1b ("tun: fix group permission check") Link: https://lore.kernel.org/netdev/CAFqZXNtkCBT4f+PwyVRmQGoT3p1eVa01fCG_aNtpt6dakXncUg@mail.gmail.com/ Signed-off-by: Willem de Bruijn Cc: Ondrej Mosnacek Cc: Stas Sergeev Link: https://patch.msgid.link/20250204161015.739430-1-willemdebruijn.kernel@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/tun.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 28624cca91f8d..acf96f2624887 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -574,18 +574,14 @@ static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb, return ret; } -static inline bool tun_capable(struct tun_struct *tun) +static inline bool tun_not_capable(struct tun_struct *tun) { const struct cred *cred = current_cred(); struct net *net = dev_net(tun->dev); - if (ns_capable(net->user_ns, CAP_NET_ADMIN)) - return 1; - if (uid_valid(tun->owner) && uid_eq(cred->euid, tun->owner)) - return 1; - if (gid_valid(tun->group) && in_egroup_p(tun->group)) - return 1; - return 0; + return ((uid_valid(tun->owner) && !uid_eq(cred->euid, tun->owner)) || + (gid_valid(tun->group) && !in_egroup_p(tun->group))) && + !ns_capable(net->user_ns, CAP_NET_ADMIN); } static void tun_set_real_num_queues(struct tun_struct *tun) @@ -2782,7 +2778,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr) !!(tun->flags & IFF_MULTI_QUEUE)) return -EINVAL; - if (!tun_capable(tun)) + if (tun_not_capable(tun)) return -EPERM; err = security_tun_dev_open(tun->security); if (err < 0) -- 2.39.5