From patchwork Tue Sep 26 20:05:04 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jordan Rife X-Patchwork-Id: 13399654 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 D3E59E7F129 for ; Tue, 26 Sep 2023 20:05:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235812AbjIZUFY (ORCPT ); Tue, 26 Sep 2023 16:05:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52210 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235817AbjIZUFX (ORCPT ); Tue, 26 Sep 2023 16:05:23 -0400 Received: from mail-io1-xd49.google.com (mail-io1-xd49.google.com [IPv6:2607:f8b0:4864:20::d49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2E23319A for ; Tue, 26 Sep 2023 13:05:15 -0700 (PDT) Received: by mail-io1-xd49.google.com with SMTP id ca18e2360f4ac-79fb6018aefso957218539f.0 for ; Tue, 26 Sep 2023 13:05:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1695758714; x=1696363514; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=Y896tdbpANmEYjOJHc8XK7Iynz1k/9wM577XVZiXiEc=; b=EFRwWR00l+HS09aReiShHLlPm3py4L1Mu3puJ7tgZJ+1QIGrKZzLe3fJcHFF1nvwhO awRtdL7kpEMEqSQprzmbBWQ1XX4Ij73uWBwt4xXip2CS0MRANBpCzmoXT2cz5mJaT+OU q+pAX6ljYtHHuLC0QV7x6+67gft8AbB9bnov+cO73xHamTpGxxQYubT79EJeMTBepeT3 WPCPzaBOBd9RoMjqcwTsbci+oVW+1H1MmQGQMpaqhVq5erjenzObgr2eHdPBwkK1QJl2 NIhShmRV86RdgfgqZrTq6qNkrAi4RN7U2Kdvh00we1Bk5cfuahxO2Y5i5Ysad+ivARKP 0E5A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695758714; x=1696363514; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Y896tdbpANmEYjOJHc8XK7Iynz1k/9wM577XVZiXiEc=; b=U8MpDrP9ffRt73QxQn6WtGOw3jSkDlOc8xUY53gMHjR2v0SyjVNcusLI4C5g+Gqi4q p+I08HK3KbC5w8iMf+MNh+iR73tiarqgMs6G3h5RJK1m5ogfr8hig7YsSaGH+hOmUKRG 5Yg1XyCnNusKAC4rmAJM1Xc/kMAh/BeWVe+Q79R9dRy222y6IAdTBFE/RpDkFqqE5DQu WXC4fzcpJur17pB8s1omd5u8XLmQEA/BxZ3yQeVknkXkPlaJywpQvY6lmBgprYdLRdBN 96OvGc53vBPCcOBVAI800INS4BO6t+EeUs6gacjJ4NXa1ZBG4hRDGkiI/EsmyVQODV22 4kWA== X-Gm-Message-State: AOJu0Yz1qoShYWkc0YJgOE14FiK+JYtFbrsTHvZHUiTYq4KfW6+HwbmJ q1YlARkv6wh7fQSEPsHJIU/ln1vBRg== X-Google-Smtp-Source: AGHT+IGAObIysfj6fqWw+uKxKjJ0fY0RpF57lGXSTezunDHESqDHeOipAl1lWQDRdfwi7TOwImqfnBF74w== X-Received: from jrife.c.googlers.com ([fda3:e722:ac3:cc00:2b:ff92:c0a8:9f]) (user=jrife job=sendgmr) by 2002:a05:6638:658e:b0:43c:e990:b090 with SMTP id fr14-20020a056638658e00b0043ce990b090mr50473jab.6.1695758714545; Tue, 26 Sep 2023 13:05:14 -0700 (PDT) Date: Tue, 26 Sep 2023 15:05:04 -0500 In-Reply-To: <20230926200505.2804266-1-jrife@google.com> Mime-Version: 1.0 References: <20230926200505.2804266-1-jrife@google.com> X-Mailer: git-send-email 2.42.0.515.g380fc7ccd1-goog Message-ID: <20230926200505.2804266-3-jrife@google.com> Subject: [PATCH net v6 2/3] net: prevent rewrite of msg_name and msg_namelen in sock_sendmsg() From: Jordan Rife To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, willemdebruijn.kernel@gmail.com, netdev@vger.kernel.org Cc: dborkman@kernel.org, horms@verge.net.au, pablo@netfilter.org, kadlec@netfilter.org, fw@strlen.de, santosh.shilimkar@oracle.com, ast@kernel.org, rdna@fb.com, linux-rdma@vger.kernel.org, rds-devel@oss.oracle.com, coreteam@netfilter.org, netfilter-devel@vger.kernel.org, ja@ssi.bg, lvs-devel@vger.kernel.org, kafai@fb.com, daniel@iogearbox.net, daan.j.demeyer@gmail.com, Jordan Rife , stable@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org Callers of sock_sendmsg(), and similarly kernel_sendmsg(), in kernel space may observe their value of msg_name change in cases where BPF sendmsg hooks rewrite the send address. This has been confirmed to break NFS mounts running in UDP mode and has the potential to break other systems. Soon, support will be added for BPF sockaddr hooks for Unix sockets which introduces the ability to modify the msg->msg_namelen value. This patch: 1) Creates a new function called __sock_sendmsg() with same logic as the old sock_sendmsg() function. 2) Replaces calls to sock_sendmsg() made by __sys_sendto() and __sys_sendmsg() with __sock_sendmsg() to avoid an unnecessary copy, as these system calls are already protected. 3) Makes a copy of msg->msg_name and to insulate callers. 4) Makes a copy of msg->msg_namelen to insulate callers in anticipation of the aforementioned change to support Unix sockets. Link: https://lore.kernel.org/netdev/20230912013332.2048422-1-jrife@google.com/ Link: https://lore.kernel.org/bpf/202309231339.L2O0CrMU-lkp@intel.com/T/#m181770af51156bdaa70fd4a4cb013ba11f28e101 Fixes: 1cedee13d25a ("bpf: Hooks for sys_sendmsg") Cc: stable@vger.kernel.org Signed-off-by: Jordan Rife --- net/socket.c | 31 +++++++++++++++++++++++++------ 1 file changed, 25 insertions(+), 6 deletions(-) diff --git a/net/socket.c b/net/socket.c index c8b08b32f097e..107a257a75186 100644 --- a/net/socket.c +++ b/net/socket.c @@ -737,6 +737,14 @@ static inline int sock_sendmsg_nosec(struct socket *sock, struct msghdr *msg) return ret; } +static int __sock_sendmsg(struct socket *sock, struct msghdr *msg) +{ + int err = security_socket_sendmsg(sock, msg, + msg_data_left(msg)); + + return err ?: sock_sendmsg_nosec(sock, msg); +} + /** * sock_sendmsg - send a message through @sock * @sock: socket @@ -747,10 +755,21 @@ static inline int sock_sendmsg_nosec(struct socket *sock, struct msghdr *msg) */ int sock_sendmsg(struct socket *sock, struct msghdr *msg) { - int err = security_socket_sendmsg(sock, msg, - msg_data_left(msg)); + struct sockaddr_storage *save_addr = (struct sockaddr_storage *)msg->msg_name; + int save_addrlen = msg->msg_namelen; + struct sockaddr_storage address; + int ret; - return err ?: sock_sendmsg_nosec(sock, msg); + if (msg->msg_name) { + memcpy(&address, msg->msg_name, msg->msg_namelen); + msg->msg_name = &address; + } + + ret = __sock_sendmsg(sock, msg); + msg->msg_name = save_addr; + msg->msg_namelen = save_addrlen; + + return ret; } EXPORT_SYMBOL(sock_sendmsg); @@ -1138,7 +1157,7 @@ static ssize_t sock_write_iter(struct kiocb *iocb, struct iov_iter *from) if (sock->type == SOCK_SEQPACKET) msg.msg_flags |= MSG_EOR; - res = sock_sendmsg(sock, &msg); + res = __sock_sendmsg(sock, &msg); *from = msg.msg_iter; return res; } @@ -2174,7 +2193,7 @@ int __sys_sendto(int fd, void __user *buff, size_t len, unsigned int flags, if (sock->file->f_flags & O_NONBLOCK) flags |= MSG_DONTWAIT; msg.msg_flags = flags; - err = sock_sendmsg(sock, &msg); + err = __sock_sendmsg(sock, &msg); out_put: fput_light(sock->file, fput_needed); @@ -2538,7 +2557,7 @@ static int ____sys_sendmsg(struct socket *sock, struct msghdr *msg_sys, err = sock_sendmsg_nosec(sock, msg_sys); goto out_freectl; } - err = sock_sendmsg(sock, msg_sys); + err = __sock_sendmsg(sock, msg_sys); /* * If this is sendmmsg() and sending to current destination address was * successful, remember it.