From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 25555280037; Tue, 12 Aug 2025 18:22:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755022937; cv=none; b=qM9d3cE1GuxM4YnG3zmo8VL2riuFbqE5dwdYRg92LaU3s/AYb6/ZIlAdcBIWm+v/8Gg40QbSjV9yfM/8Ic7boBy/J2p34EaShaNeYAIaGaQmrEfpDdnOnYsv+mmyjwP2oXvMNT3F3vngvyfqWKi8EMb+Rm5uzzlHaMNLKFtTgcI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755022937; c=relaxed/simple; bh=8KsLHJJnQI2yIjElGneCNNJjn4xGjBU9p0/kwIJTx0I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YchOMi7eVzvwQryNZP2kEg8nVnIHVVeVQN09rwZDA2IXpomp8Z9u4UL57vL8Mg2tEDFHzc/caxAtaQJ0YDpAJvVHCuOtWaJjplBjATvZbWtAcgtFRixBJzyaS8x5g+KfJjM4f/yCGNBPeshehmFq9qO9+Q+so1Edf3iE4slhnEA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=gLwselyc; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="gLwselyc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85A1EC4CEF0; Tue, 12 Aug 2025 18:22:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755022937; bh=8KsLHJJnQI2yIjElGneCNNJjn4xGjBU9p0/kwIJTx0I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gLwselycFtJaFXq9Jfw7b6gOIyx2fuREmLKvmQHd/rZMyS1VO9Cj6QYx1Iz2vrs7Q mbZJ3+dwSKNx8fnQewY2CRLb+0Zr4XqG1gy41+9tmohA8PJFYaZyYQSvy841GPJjPd c3VDnOHNmb7RLXQ44wajg/36F8hpHvN4SKHxVua0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Trond Myklebust , Scott Mayhew , Olga Kornievskaia , Trond Myklebust , Sasha Levin Subject: [PATCH 6.12 303/369] sunrpc: fix client side handling of tls alerts Date: Tue, 12 Aug 2025 19:30:00 +0200 Message-ID: <20250812173028.131151781@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250812173014.736537091@linuxfoundation.org> References: <20250812173014.736537091@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Olga Kornievskaia [ Upstream commit cc5d59081fa26506d02de2127ab822f40d88bc5a ] A security exploit was discovered in NFS over TLS in tls_alert_recv due to its assumption that there is valid data in the msghdr's iterator's kvec. Instead, this patch proposes the rework how control messages are setup and used by sock_recvmsg(). If no control message structure is setup, kTLS layer will read and process TLS data record types. As soon as it encounters a TLS control message, it would return an error. At that point, NFS can setup a kvec backed control buffer and read in the control message such as a TLS alert. Scott found that a msg iterator can advance the kvec pointer as a part of the copy process thus we need to revert the iterator before calling into the tls_alert_recv. Fixes: dea034b963c8 ("SUNRPC: Capture CMSG metadata on client-side receive") Suggested-by: Trond Myklebust Suggested-by: Scott Mayhew Signed-off-by: Olga Kornievskaia Link: https://lore.kernel.org/r/20250731180058.4669-3-okorniev@redhat.com Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin --- net/sunrpc/xprtsock.c | 40 ++++++++++++++++++++++++++++++---------- 1 file changed, 30 insertions(+), 10 deletions(-) diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index 67d099c7c662..1397bb48cdde 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -358,7 +358,7 @@ xs_alloc_sparse_pages(struct xdr_buf *buf, size_t want, gfp_t gfp) static int xs_sock_process_cmsg(struct socket *sock, struct msghdr *msg, - struct cmsghdr *cmsg, int ret) + unsigned int *msg_flags, struct cmsghdr *cmsg, int ret) { u8 content_type = tls_get_record_type(sock->sk, cmsg); u8 level, description; @@ -371,7 +371,7 @@ xs_sock_process_cmsg(struct socket *sock, struct msghdr *msg, * record, even though there might be more frames * waiting to be decrypted. */ - msg->msg_flags &= ~MSG_EOR; + *msg_flags &= ~MSG_EOR; break; case TLS_RECORD_TYPE_ALERT: tls_alert_recv(sock->sk, msg, &level, &description); @@ -386,19 +386,33 @@ xs_sock_process_cmsg(struct socket *sock, struct msghdr *msg, } static int -xs_sock_recv_cmsg(struct socket *sock, struct msghdr *msg, int flags) +xs_sock_recv_cmsg(struct socket *sock, unsigned int *msg_flags, int flags) { union { struct cmsghdr cmsg; u8 buf[CMSG_SPACE(sizeof(u8))]; } u; + u8 alert[2]; + struct kvec alert_kvec = { + .iov_base = alert, + .iov_len = sizeof(alert), + }; + struct msghdr msg = { + .msg_flags = *msg_flags, + .msg_control = &u, + .msg_controllen = sizeof(u), + }; int ret; - msg->msg_control = &u; - msg->msg_controllen = sizeof(u); - ret = sock_recvmsg(sock, msg, flags); - if (msg->msg_controllen != sizeof(u)) - ret = xs_sock_process_cmsg(sock, msg, &u.cmsg, ret); + iov_iter_kvec(&msg.msg_iter, ITER_DEST, &alert_kvec, 1, + alert_kvec.iov_len); + ret = sock_recvmsg(sock, &msg, flags); + if (ret > 0 && + tls_get_record_type(sock->sk, &u.cmsg) == TLS_RECORD_TYPE_ALERT) { + iov_iter_revert(&msg.msg_iter, ret); + ret = xs_sock_process_cmsg(sock, &msg, msg_flags, &u.cmsg, + -EAGAIN); + } return ret; } @@ -408,7 +422,13 @@ xs_sock_recvmsg(struct socket *sock, struct msghdr *msg, int flags, size_t seek) ssize_t ret; if (seek != 0) iov_iter_advance(&msg->msg_iter, seek); - ret = xs_sock_recv_cmsg(sock, msg, flags); + ret = sock_recvmsg(sock, msg, flags); + /* Handle TLS inband control message lazily */ + if (msg->msg_flags & MSG_CTRUNC) { + msg->msg_flags &= ~(MSG_CTRUNC | MSG_EOR); + if (ret == 0 || ret == -EIO) + ret = xs_sock_recv_cmsg(sock, &msg->msg_flags, flags); + } return ret > 0 ? ret + seek : ret; } @@ -434,7 +454,7 @@ xs_read_discard(struct socket *sock, struct msghdr *msg, int flags, size_t count) { iov_iter_discard(&msg->msg_iter, ITER_DEST, count); - return xs_sock_recv_cmsg(sock, msg, flags); + return xs_sock_recvmsg(sock, msg, flags, 0); } #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE -- 2.39.5