From patchwork Sat Jul 8 02:34:19 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anjali Kulkarni X-Patchwork-Id: 13305552 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 27B9B1FA1 for ; Sat, 8 Jul 2023 02:34:49 +0000 (UTC) Received: from mx0a-00069f02.pphosted.com (mx0a-00069f02.pphosted.com [205.220.165.32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 36A23210B; Fri, 7 Jul 2023 19:34:47 -0700 (PDT) Received: from pps.filterd (m0246627.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 3682CoFH027406; Sat, 8 Jul 2023 02:34:27 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=corp-2023-03-30; bh=qmeUsS7zFBj7NRNT7eXQe9a1TTvvEdA754mUtEqiSjQ=; b=IqT5LpE+pcLDvCoBl8SHXMHLQkV2Rc3AnKtwZL67ZWsFv/qvTKreJ0GJhLOzXD0kirTl nlVDq1CjVzdKvUP2DRZSxV65tqM/VFJ2W2kXLNun5fb9YewMeAKupD+ldm338obPX2d7 h69aAZLiMSf9uCSNDcQlmYlstDoOO1c1elf1wl5C+TI7qcVzxi6g0Tw+Nig70VitIohg FZYhAWgRQ01sl0UOiCzDzIJ863eQP8VBYLeKJ0gDsabmnG/V77qzYBXkuQcf6rEGtF0I YPyBPkdnKnfDxd2LT0mYveYBfgmsXMnzQ8QKBg47d15zF4KIhhOcceieI4bu7TGfLVw2 KQ== Received: from phxpaimrmta02.imrmtpd1.prodappphxaev1.oraclevcn.com (phxpaimrmta02.appoci.oracle.com [147.154.114.232]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 3rpxd0r0ve-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 08 Jul 2023 02:34:27 +0000 Received: from pps.filterd (phxpaimrmta02.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by phxpaimrmta02.imrmtpd1.prodappphxaev1.oraclevcn.com (8.17.1.19/8.17.1.19) with ESMTP id 3681X7J5034615; Sat, 8 Jul 2023 02:34:26 GMT Received: from pps.reinject (localhost [127.0.0.1]) by phxpaimrmta02.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTPS id 3rpx81h03s-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 08 Jul 2023 02:34:26 +0000 Received: from phxpaimrmta02.imrmtpd1.prodappphxaev1.oraclevcn.com (phxpaimrmta02.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 3682YL38033474; Sat, 8 Jul 2023 02:34:26 GMT Received: from ca-dev112.us.oracle.com (ca-dev112.us.oracle.com [10.129.136.47]) by phxpaimrmta02.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTP id 3rpx81h01x-6; Sat, 08 Jul 2023 02:34:26 +0000 From: Anjali Kulkarni To: davem@davemloft.net Cc: Liam.Howlett@Oracle.com, akpm@linux-foundation.org, david@fries.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, zbr@ioremap.net, brauner@kernel.org, johannes@sipsolutions.net, ecree.xilinx@gmail.com, leon@kernel.org, keescook@chromium.org, socketcan@hartkopp.net, petrm@nvidia.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, anjali.k.kulkarni@oracle.com Subject: [PATCH v9 5/6] connector/cn_proc: Allow non-root users access Date: Fri, 7 Jul 2023 19:34:19 -0700 Message-ID: <20230708023420.3931239-6-anjali.k.kulkarni@oracle.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230708023420.3931239-1-anjali.k.kulkarni@oracle.com> References: <20230708023420.3931239-1-anjali.k.kulkarni@oracle.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.957,Hydra:6.0.591,FMLib:17.11.176.26 definitions=2023-07-07_16,2023-07-06_02,2023-05-22_02 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 mlxlogscore=999 adultscore=0 mlxscore=0 spamscore=0 phishscore=0 malwarescore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2305260000 definitions=main-2307080022 X-Proofpoint-GUID: bOTcJhzuoU2rDmAG-dqaMJcYXUbNtDNA X-Proofpoint-ORIG-GUID: bOTcJhzuoU2rDmAG-dqaMJcYXUbNtDNA X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H5,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE, T_SCC_BODY_TEXT_LINE 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 There were a couple of reasons for not allowing non-root users access initially - one is there was some point no proper receive buffer management in place for netlink multicast. But that should be long fixed. See link below for more context. Second is that some of the messages may contain data that is root only. But this should be handled with a finer granularity, which is being done at the protocol layer. The only problematic protocols are nf_queue and the firewall netlink. Hence, this restriction for non-root access was relaxed for NETLINK_ROUTE initially: https://lore.kernel.org/all/20020612013101.A22399@wotan.suse.de/ This restriction has also been removed for following protocols: NETLINK_KOBJECT_UEVENT, NETLINK_AUDIT, NETLINK_SOCK_DIAG, NETLINK_GENERIC, NETLINK_SELINUX. Since process connector messages are not sensitive (process fork, exit notifications etc.), and anyone can read /proc data, we can allow non-root access here. However, since process event notification is not the only consumer of NETLINK_CONNECTOR, we can make this change even more fine grained than the protocol level, by checking for multicast group within the protocol. Allow non-root access for NETLINK_CONNECTOR via NL_CFG_F_NONROOT_RECV but add new bind function cn_bind(), which allows non-root access only for CN_IDX_PROC multicast group. Signed-off-by: Anjali Kulkarni --- drivers/connector/cn_proc.c | 6 ------ drivers/connector/connector.c | 19 +++++++++++++++++++ 2 files changed, 19 insertions(+), 6 deletions(-) diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c index dfc84d44f804..05d562e9c8b1 100644 --- a/drivers/connector/cn_proc.c +++ b/drivers/connector/cn_proc.c @@ -410,12 +410,6 @@ static void cn_proc_mcast_ctl(struct cn_msg *msg, !task_is_in_init_pid_ns(current)) return; - /* Can only change if privileged. */ - if (!__netlink_ns_capable(nsp, &init_user_ns, CAP_NET_ADMIN)) { - err = EPERM; - goto out; - } - if (msg->len == sizeof(*pinput)) { pinput = (struct proc_input *)msg->data; mc_op = pinput->mcast_op; diff --git a/drivers/connector/connector.c b/drivers/connector/connector.c index d1179df2b0ba..7f7b94f616a6 100644 --- a/drivers/connector/connector.c +++ b/drivers/connector/connector.c @@ -166,6 +166,23 @@ static int cn_call_callback(struct sk_buff *skb) return err; } +/* + * Allow non-root access for NETLINK_CONNECTOR family having CN_IDX_PROC + * multicast group. + */ +static int cn_bind(struct net *net, int group) +{ + unsigned long groups = (unsigned long) group; + + if (ns_capable(net->user_ns, CAP_NET_ADMIN)) + return 0; + + if (test_bit(CN_IDX_PROC - 1, &groups)) + return 0; + + return -EPERM; +} + static void cn_release(struct sock *sk, unsigned long *groups) { if (groups && test_bit(CN_IDX_PROC - 1, groups)) { @@ -261,6 +278,8 @@ static int cn_init(void) struct netlink_kernel_cfg cfg = { .groups = CN_NETLINK_USERS + 0xf, .input = cn_rx_skb, + .flags = NL_CFG_F_NONROOT_RECV, + .bind = cn_bind, .release = cn_release, };