From patchwork Thu Apr 20 20:27:09 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anjali Kulkarni X-Patchwork-Id: 13219167 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C0520C77B73 for ; Thu, 20 Apr 2023 20:28:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230049AbjDTU2J (ORCPT ); Thu, 20 Apr 2023 16:28:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45680 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232493AbjDTU1q (ORCPT ); Thu, 20 Apr 2023 16:27:46 -0400 Received: from mx0b-00069f02.pphosted.com (mx0b-00069f02.pphosted.com [205.220.177.32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AB97940CE; Thu, 20 Apr 2023 13:27:38 -0700 (PDT) Received: from pps.filterd (m0246632.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 33KKFDA8002097; Thu, 20 Apr 2023 20:27:25 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=gXl2kPXJPf/jSKBw0vAfbHVROAJisKoHzvhm0NlxHu4=; b=s4bH2Aov8vHggEV1QQXJHyu/WJDOOUVYZFkGExIgkwurw3zP97upL15oioxwirfJqM6f FsuNFFjLbfvJ7/mzbL1buGB6lrx/D97YpLJR1SiqdODk2fFp4/qldGl/8KXsIqHTmMAC 44Z1+SFPClI3x+zIauwsq7weWUSPni6qlBQ3I3xzOag+1auCvIQQYM8e/brmga1iIDSl xKDLsLz6katwli0FenSsrjFVnExFPcHrQEwwza8sG9eDN2zzVT1RJxRWsW7z1shFzQwG QrEj8k4z0zFi8IYuaXSsZHoSGMLoPuJJqLC3ePH9ER1+iwpSeUonHsLbXjUJ/0LeOdKr gA== Received: from iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (iadpaimrmta03.appoci.oracle.com [130.35.103.27]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 3pykhu3v7g-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 20 Apr 2023 20:27:24 +0000 Received: from pps.filterd (iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com [127.0.0.1]) by iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (8.17.1.19/8.17.1.19) with ESMTP id 33KJ6bHs026349; Thu, 20 Apr 2023 20:27:24 GMT Received: from pps.reinject (localhost [127.0.0.1]) by iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (PPS) with ESMTPS id 3pyjcf2ecv-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 20 Apr 2023 20:27:24 +0000 Received: from iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 33KKRCYi027077; Thu, 20 Apr 2023 20:27:23 GMT Received: from ca-dev112.us.oracle.com (ca-dev112.us.oracle.com [10.129.136.47]) by iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (PPS) with ESMTP id 3pyjcf2e4y-7; Thu, 20 Apr 2023 20:27:23 +0000 From: Anjali Kulkarni To: davem@davemloft.net Cc: 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 v5 6/6] connector/cn_proc: Allow non-root users access Date: Thu, 20 Apr 2023 13:27:09 -0700 Message-Id: <20230420202709.3207243-7-anjali.k.kulkarni@oracle.com> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230420202709.3207243-1-anjali.k.kulkarni@oracle.com> References: <20230420202709.3207243-1-anjali.k.kulkarni@oracle.com> MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-04-20_15,2023-04-20_01,2023-02-09_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 mlxlogscore=999 mlxscore=0 adultscore=0 suspectscore=0 phishscore=0 spamscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2303200000 definitions=main-2304200171 X-Proofpoint-GUID: 3b8dCK71HrXf8vU5h-QkROO1YAmgi2Hf X-Proofpoint-ORIG-GUID: 3b8dCK71HrXf8vU5h-QkROO1YAmgi2Hf Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 | 7 ------- drivers/connector/connector.c | 14 ++++++++++++++ 2 files changed, 14 insertions(+), 7 deletions(-) diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c index 35bec1fd7ee0..046a8c1d8577 100644 --- a/drivers/connector/cn_proc.c +++ b/drivers/connector/cn_proc.c @@ -408,12 +408,6 @@ 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; @@ -460,7 +454,6 @@ static void cn_proc_mcast_ctl(struct cn_msg *msg, break; } -out: cn_proc_ack(err, msg->seq, msg->ack); } diff --git a/drivers/connector/connector.c b/drivers/connector/connector.c index d1179df2b0ba..193d3056de64 100644 --- a/drivers/connector/connector.c +++ b/drivers/connector/connector.c @@ -166,6 +166,18 @@ static int cn_call_callback(struct sk_buff *skb) return err; } +static int cn_bind(struct net *net, int group) +{ + unsigned long groups = 0; + 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 +273,8 @@ 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, };