From patchwork Tue Sep 19 17:52:54 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jordan Rife X-Patchwork-Id: 13391718 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 B7B918460 for ; Tue, 19 Sep 2023 17:53:11 +0000 (UTC) Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF9B98F for ; Tue, 19 Sep 2023 10:53:08 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id 3f1490d57ef6-d817775453dso6023743276.2 for ; Tue, 19 Sep 2023 10:53:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1695145988; x=1695750788; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=qQrU6vyyJK+GpT4LI0fE5qrjc1subTmaNwUd6fCEDnk=; b=UdMK2/GAiIcYKbSCU2NzF2OfoRrK/BwzwC2mdG7chDSb1yyhEZDui20rNe8ZE+PipI aweEiHOL7S16kCjvK9SraDEDDGXQbC4vCjDNK8MrEUSqWnNstCZWRYwQblXulWDd0yf0 qHZMG8R1VlFKnUyAAlJkeKU4ZJ9K1Orwmi+JwyO+y5+Db5vALMdhEOA9OfBMuCA71kR5 EvumUP4J3bbsi1zB85nimpuDP34xIoehNEqkgTjnl1a3jHrdk3U9hS+ObjRR/KqI5BMJ 9ZVPhIvkz5Sg+E/+jeHgmEXHt3SZXanV6jvSZxbDDSw0uUC4MCd2UYaL+4PrZq6ZYMxc TRkA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695145988; x=1695750788; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=qQrU6vyyJK+GpT4LI0fE5qrjc1subTmaNwUd6fCEDnk=; b=CX9gxDRBiu7pbbcR4kWAYViU86mK/S20geVZQEXM1G6oSmKRizQDCKAPIQ8VcMu7q6 GmXD0eAifTofP4MuhT2gx0FOCaCQCsS+EAkiIZaIKBEfGd1Xomr9rq1L6EHlc5M6XJtf QlJeqRSKk3+xEoI4tVTQk0nsIW9YMVe9AcCwqysA4OMBBRhv7Y/Y+P47wYznqPAo4p/K rISms8DbV1cD2JBLj//yn5a1LRZsA0nq4WhfUWUvVrP6FEXb5t6mxAy+Hpjf0vUsjGnT +JeEvqGSMtTyDtPva4ZDBINSqMQUFWJ6JwGVfMt6iP+8mU/2IgELpDqxoELKgFPQX39X paRw== X-Gm-Message-State: AOJu0YzIFFZ0oak+rt5cdlypJvD7fUvOP4o+HGlfFHNN+gLAxLBAXlBE 8UfTOsE3xgRL8imxrnIxmBmvopfnng== X-Google-Smtp-Source: AGHT+IETHz79JtKbYe4YlHoLjiYBboCMucFwvA1gNs5nXByDf3BIdsqRTUVYiJExuerG3s27zBa9cqYPDA== X-Received: from jrife.c.googlers.com ([fda3:e722:ac3:cc00:2b:ff92:c0a8:9f]) (user=jrife job=sendgmr) by 2002:a5b:dc7:0:b0:c78:c530:6345 with SMTP id t7-20020a5b0dc7000000b00c78c5306345mr5693ybr.7.1695145988018; Tue, 19 Sep 2023 10:53:08 -0700 (PDT) Date: Tue, 19 Sep 2023 12:52:54 -0500 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.42.0.459.ge4e396fd5e-goog Message-ID: <20230919175254.144417-1-jrife@google.com> Subject: [PATCH net v4 2/3] net: prevent rewrite of msg_name 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, Jordan Rife , stable@vger.kernel.org X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 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. 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) Modifies sock_sendmsg() so that it makes a copy of msg_name if present before passing it down the stack to insulate callers from changes to the send address. Link: https://lore.kernel.org/netdev/20230912013332.2048422-1-jrife@google.com/ Fixes: 1cedee13d25a ("bpf: Hooks for sys_sendmsg") Cc: stable@vger.kernel.org Signed-off-by: Jordan Rife Reviewed-by: Willem de Bruijn --- v3->v4: Maintain reverse xmas tree order for variable declarations. Remove precondition check for msg_namelen. v2->v3: Add "Fixes" tag. v1->v2: Split up original patch into patch series. Perform address copy in sock_sendmsg() instead of sock->ops->sendmsg(). net/socket.c | 29 +++++++++++++++++++++++------ 1 file changed, 23 insertions(+), 6 deletions(-) diff --git a/net/socket.c b/net/socket.c index c8b08b32f097e..a39ec136f5cff 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 +755,19 @@ 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; + 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; + + return ret; } EXPORT_SYMBOL(sock_sendmsg); @@ -1138,7 +1155,7 @@ 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 +2191,7 @@ 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 +2555,7 @@ 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.