From patchwork Thu Jul 9 18:26:36 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 11654915 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6D92F913 for ; Thu, 9 Jul 2020 18:27:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4CB32207D0 for ; Thu, 9 Jul 2020 18:27:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="Z/SBBrai" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727847AbgGIS1v (ORCPT ); Thu, 9 Jul 2020 14:27:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55284 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726260AbgGIS0u (ORCPT ); Thu, 9 Jul 2020 14:26:50 -0400 Received: from mail-pl1-x642.google.com (mail-pl1-x642.google.com [IPv6:2607:f8b0:4864:20::642]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 74368C08C5CE for ; Thu, 9 Jul 2020 11:26:50 -0700 (PDT) Received: by mail-pl1-x642.google.com with SMTP id d10so1172978pll.3 for ; Thu, 09 Jul 2020 11:26:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=gBY5M3TNmTDqA1bjL3Jjd2nDvBr+rR1mQXBFsWn1CQs=; b=Z/SBBrai2x+BBSEUc6N28u3SdpQIVYQvqvzxgZa++Q+lxnUT3SQS6C93G+gyNmDJyp G9NKXhnct9cCfT8hHvBPH034zHim5LwRyp/AVC+53x6uR5vefh90fzKhwuPFhy87LK/W bhuamtkXjM0DqKh3bzbohWkiK158TXa8btjoo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=gBY5M3TNmTDqA1bjL3Jjd2nDvBr+rR1mQXBFsWn1CQs=; b=kh8yvhJ+tfnNnUL79SM8pbiE82vjeZ534+J724dAwPy9pMReDd0ttAHIo2Fjf/Dqyc kyeOwB9d7O+6ZOBBsmiHG1AT9l7dbSeBek9rTNyDphq5YCf3DZbcwt8k3BoL0LJh8HX/ NZ3/nR2r9VRim3Ob6xUGvXClrUfAq5RNFw5lU3WNEI87Odvj4JbVesgKaz1XAPtS1j/o o1tMSKW49r7FSPmn88zni/HpcXrB/yJSTggpCM676F+JoYwHSgDAPCJx+zvG1/hwfq/j H8mP92t1YSSDoQt631tZ0DyPgWNqgymJwFCG6QKcR5Ce24T84FrvvTP9UQMzO5HMPhCU yUqw== X-Gm-Message-State: AOAM5318621vpJOvG+0wmtFy4+uL5O0azDM08ibA6xyx8g8/sqVFxk83 3wFPRylw8AYhYRSQjJCRAI33NA== X-Google-Smtp-Source: ABdhPJx4h/+lsPEnqV3d2BF+grHojn5a/CNAZlzUT8KQsoJV3wNBqQhfg3tjN57T9DNZlJUXNEMcpw== X-Received: by 2002:a17:902:bcc1:: with SMTP id o1mr54297569pls.246.1594319209945; Thu, 09 Jul 2020 11:26:49 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id d190sm3351764pfd.199.2020.07.09.11.26.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Jul 2020 11:26:47 -0700 (PDT) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , Christian Brauner , Sargun Dhillon , Christian Brauner , Tycho Andersen , David Laight , Christoph Hellwig , "David S. Miller" , Jakub Kicinski , Alexander Viro , Aleksa Sarai , Matt Denton , Jann Horn , Chris Palmer , Robert Sesek , Giuseppe Scrivano , Greg Kroah-Hartman , Andy Lutomirski , Will Drewry , Shuah Khan , netdev@vger.kernel.org, containers@lists.linux-foundation.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH v7 3/9] net/scm: Regularize compat handling of scm_detach_fds() Date: Thu, 9 Jul 2020 11:26:36 -0700 Message-Id: <20200709182642.1773477-4-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200709182642.1773477-1-keescook@chromium.org> References: <20200709182642.1773477-1-keescook@chromium.org> MIME-Version: 1.0 Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Duplicate the cleanups from commit 2618d530dd8b ("net/scm: cleanup scm_detach_fds") into the compat code. Replace open-coded __receive_sock() with a call to the helper. Move the check added in commit 1f466e1f15cf ("net: cleanly handle kernel vs user buffers for ->msg_control") to before the compat call, even though it should be impossible for an in-kernel call to also be compat. Correct the int "flags" argument to unsigned int to match fd_install() and similar APIs. Regularize any remaining differences, including a whitespace issue, a checkpatch warning, and add the check from commit 6900317f5eff ("net, scm: fix PaX detected msg_controllen overflow in scm_detach_fds") which fixed an overflow unique to 64-bit. To avoid confusion when comparing the compat handler to the native handler, just include the same check in the compat handler. Acked-by: Christian Brauner Signed-off-by: Kees Cook --- include/net/scm.h | 1 + net/compat.c | 56 +++++++++++++++++++++-------------------------- net/core/scm.c | 27 ++++++++++------------- 3 files changed, 37 insertions(+), 47 deletions(-) diff --git a/include/net/scm.h b/include/net/scm.h index 1ce365f4c256..581a94d6c613 100644 --- a/include/net/scm.h +++ b/include/net/scm.h @@ -37,6 +37,7 @@ struct scm_cookie { #endif }; +int __scm_install_fd(struct file *file, int __user *ufd, unsigned int o_flags); void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm); void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm); int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm); diff --git a/net/compat.c b/net/compat.c index 2937b816107d..27d477fdcaa0 100644 --- a/net/compat.c +++ b/net/compat.c @@ -281,40 +281,31 @@ int put_cmsg_compat(struct msghdr *kmsg, int level, int type, int len, void *dat return 0; } -void scm_detach_fds_compat(struct msghdr *kmsg, struct scm_cookie *scm) +static int scm_max_fds_compat(struct msghdr *msg) { - struct compat_cmsghdr __user *cm = (struct compat_cmsghdr __user *) kmsg->msg_control; - int fdmax = (kmsg->msg_controllen - sizeof(struct compat_cmsghdr)) / sizeof(int); - int fdnum = scm->fp->count; - struct file **fp = scm->fp->fp; - int __user *cmfptr; - int err = 0, i; + if (msg->msg_controllen <= sizeof(struct compat_cmsghdr)) + return 0; + return (msg->msg_controllen - sizeof(struct compat_cmsghdr)) / sizeof(int); +} - if (fdnum < fdmax) - fdmax = fdnum; +void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm) +{ + struct compat_cmsghdr __user *cm = + (struct compat_cmsghdr __user *)msg->msg_control; + unsigned int o_flags = (msg->msg_flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0; + int fdmax = min_t(int, scm_max_fds_compat(msg), scm->fp->count); + int __user *cmsg_data = CMSG_USER_DATA(cm); + int err = 0, i; - for (i = 0, cmfptr = (int __user *) CMSG_COMPAT_DATA(cm); i < fdmax; i++, cmfptr++) { - int new_fd; - err = security_file_receive(fp[i]); + for (i = 0; i < fdmax; i++) { + err = __scm_install_fd(scm->fp->fp[i], cmsg_data + i, o_flags); if (err) break; - err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & kmsg->msg_flags - ? O_CLOEXEC : 0); - if (err < 0) - break; - new_fd = err; - err = put_user(new_fd, cmfptr); - if (err) { - put_unused_fd(new_fd); - break; - } - /* Bump the usage count and install the file. */ - __receive_sock(fp[i]); - fd_install(new_fd, get_file(fp[i])); } if (i > 0) { int cmlen = CMSG_COMPAT_LEN(i * sizeof(int)); + err = put_user(SOL_SOCKET, &cm->cmsg_level); if (!err) err = put_user(SCM_RIGHTS, &cm->cmsg_type); @@ -322,16 +313,19 @@ void scm_detach_fds_compat(struct msghdr *kmsg, struct scm_cookie *scm) err = put_user(cmlen, &cm->cmsg_len); if (!err) { cmlen = CMSG_COMPAT_SPACE(i * sizeof(int)); - kmsg->msg_control += cmlen; - kmsg->msg_controllen -= cmlen; + if (msg->msg_controllen < cmlen) + cmlen = msg->msg_controllen; + msg->msg_control += cmlen; + msg->msg_controllen -= cmlen; } } - if (i < fdnum) - kmsg->msg_flags |= MSG_CTRUNC; + + if (i < scm->fp->count || (scm->fp->count && fdmax <= 0)) + msg->msg_flags |= MSG_CTRUNC; /* - * All of the files that fit in the message have had their - * usage counts incremented, so we just free the list. + * All of the files that fit in the message have had their usage counts + * incremented, so we just free the list. */ __scm_destroy(scm); } diff --git a/net/core/scm.c b/net/core/scm.c index 875df1c2989d..44f03213dcab 100644 --- a/net/core/scm.c +++ b/net/core/scm.c @@ -280,9 +280,8 @@ void put_cmsg_scm_timestamping(struct msghdr *msg, struct scm_timestamping_inter } EXPORT_SYMBOL(put_cmsg_scm_timestamping); -static int __scm_install_fd(struct file *file, int __user *ufd, int o_flags) +int __scm_install_fd(struct file *file, int __user *ufd, unsigned int o_flags) { - struct socket *sock; int new_fd; int error; @@ -300,12 +299,8 @@ static int __scm_install_fd(struct file *file, int __user *ufd, int o_flags) return error; } - /* Bump the usage count and install the file. */ - sock = sock_from_file(file, &error); - if (sock) { - sock_update_netprioidx(&sock->sk->sk_cgrp_data); - sock_update_classid(&sock->sk->sk_cgrp_data); - } + /* Bump the sock usage counts, if any. */ + __receive_sock(file); fd_install(new_fd, get_file(file)); return 0; } @@ -319,29 +314,29 @@ static int scm_max_fds(struct msghdr *msg) void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm) { - struct cmsghdr __user *cm - = (__force struct cmsghdr __user*)msg->msg_control; - int o_flags = (msg->msg_flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0; + struct cmsghdr __user *cm = + (__force struct cmsghdr __user *)msg->msg_control; + unsigned int o_flags = (msg->msg_flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0; int fdmax = min_t(int, scm_max_fds(msg), scm->fp->count); int __user *cmsg_data = CMSG_USER_DATA(cm); int err = 0, i; + /* no use for FD passing from kernel space callers */ + if (WARN_ON_ONCE(!msg->msg_control_is_user)) + return; + if (msg->msg_flags & MSG_CMSG_COMPAT) { scm_detach_fds_compat(msg, scm); return; } - /* no use for FD passing from kernel space callers */ - if (WARN_ON_ONCE(!msg->msg_control_is_user)) - return; - for (i = 0; i < fdmax; i++) { err = __scm_install_fd(scm->fp->fp[i], cmsg_data + i, o_flags); if (err) break; } - if (i > 0) { + if (i > 0) { int cmlen = CMSG_LEN(i * sizeof(int)); err = put_user(SOL_SOCKET, &cm->cmsg_level);