From patchwork Tue Aug 15 13:56:02 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dong Chenchen X-Patchwork-Id: 13353832 X-Patchwork-Delegate: kuba@kernel.org Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 1B4A5111AD for ; Tue, 15 Aug 2023 13:56:44 +0000 (UTC) Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5612F198A; Tue, 15 Aug 2023 06:56:43 -0700 (PDT) Received: from kwepemi500026.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4RQCSD6T8TzVjNL; Tue, 15 Aug 2023 21:54:36 +0800 (CST) Received: from localhost.localdomain (10.175.104.82) by kwepemi500026.china.huawei.com (7.221.188.247) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Tue, 15 Aug 2023 21:56:40 +0800 From: Dong Chenchen To: CC: , , , , Laszlo Ersek , Eric Dumazet , Lorenzo Colitti , Paolo Abeni , Pietro Borrello , , , "David S . Miller" , Greg Kroah-Hartman , Dong Chenchen Subject: [PATCH OLK-5.10 v2 2/2] net: tap_open(): set sk_uid from current_fsuid() Date: Tue, 15 Aug 2023 21:56:02 +0800 Message-ID: <20230815135602.1014881-3-dongchenchen2@huawei.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230815135602.1014881-1-dongchenchen2@huawei.com> References: <20230815135602.1014881-1-dongchenchen2@huawei.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Originating-IP: [10.175.104.82] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemi500026.china.huawei.com (7.221.188.247) X-CFilter-Loop: Reflected X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_MED, RCVD_IN_MSPIKE_H5,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: kuba@kernel.org From: Laszlo Ersek stable inclusion from stable-v5.10.189 commit 33a339e717be2c88b7ad11375165168d5b40e38e category: bugfix bugzilla: 189104, https://gitee.com/src-openeuler/kernel/issues/I7QXHX CVE: CVE-2023-4194 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=33a339e717be2c88b7ad11375165168d5b40e38e --------------------------- commit 5c9241f3ceab3257abe2923a59950db0dc8bb737 upstream. Commit 66b2c338adce initializes the "sk_uid" field in the protocol socket (struct sock) from the "/dev/tapX" device node's owner UID. Per original commit 86741ec25462 ("net: core: Add a UID field to struct sock.", 2016-11-04), that's wrong: the idea is to cache the UID of the userspace process that creates the socket. Commit 86741ec25462 mentions socket() and accept(); with "tap", the action that creates the socket is open("/dev/tapX"). Therefore the device node's owner UID is irrelevant. In most cases, "/dev/tapX" will be owned by root, so in practice, commit 66b2c338adce has no observable effect: - before, "sk_uid" would be zero, due to undefined behavior (CVE-2023-1076), - after, "sk_uid" would be zero, due to "/dev/tapX" being owned by root. What matters is the (fs)UID of the process performing the open(), so cache that in "sk_uid". Cc: Eric Dumazet Cc: Lorenzo Colitti Cc: Paolo Abeni Cc: Pietro Borrello Cc: netdev@vger.kernel.org Cc: stable@vger.kernel.org Fixes: 66b2c338adce ("tap: tap_open(): correctly initialize socket uid") Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2173435 Signed-off-by: Laszlo Ersek Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman Signed-off-by: Dong Chenchen --- drivers/net/tap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/tap.c b/drivers/net/tap.c index d9018d9fe310..2c9ae02ada3e 100644 --- a/drivers/net/tap.c +++ b/drivers/net/tap.c @@ -523,7 +523,7 @@ static int tap_open(struct inode *inode, struct file *file) q->sock.state = SS_CONNECTED; q->sock.file = file; q->sock.ops = &tap_socket_ops; - sock_init_data_uid(&q->sock, &q->sk, inode->i_uid); + sock_init_data_uid(&q->sock, &q->sk, current_fsuid()); q->sk.sk_write_space = tap_sock_write_space; q->sk.sk_destruct = tap_sock_destruct; q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP;