From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: + exec-move-path_noexec-check-earlier.patch added to -mm tree Date: Fri, 05 Jun 2020 17:40:03 -0700 Message-ID: <20200606004003.9yjXKigQl%akpm@linux-foundation.org> References: <20200604164523.e15f3177f4b69dcb4f2534a1@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:42474 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726803AbgFFAkF (ORCPT ); Fri, 5 Jun 2020 20:40:05 -0400 In-Reply-To: <20200604164523.e15f3177f4b69dcb4f2534a1@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: christian.brauner@ubuntu.com, cyphar@cyphar.com, dvyukov@google.com, ebiggers3@gmail.com, keescook@chromium.org, mm-commits@vger.kernel.org, penguin-kernel@I-love.SAKURA.ne.jp, viro@zeniv.linux.org.uk The patch titled Subject: exec: move path_noexec() check earlier has been added to the -mm tree. Its filename is exec-move-path_noexec-check-earlier.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/exec-move-path_noexec-check-earlier.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/exec-move-path_noexec-check-earlier.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Kees Cook Subject: exec: move path_noexec() check earlier The path_noexec() check, like the regular file check, was happening too late, letting LSMs see impossible execve()s. Check it earlier as well in may_open() and collect the redundant fs/exec.c path_noexec() test under the same robustness comment as the S_ISREG() check. My notes on the call path, and related arguments, checks, etc: do_open_execat() struct open_flags open_exec_flags = { .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, .acc_mode = MAY_EXEC, ... do_filp_open(dfd, filename, open_flags) path_openat(nameidata, open_flags, flags) file = alloc_empty_file(open_flags, current_cred()); do_open(nameidata, file, open_flags) may_open(path, acc_mode, open_flag) /* new location of MAY_EXEC vs path_noexec() test */ inode_permission(inode, MAY_OPEN | acc_mode) security_inode_permission(inode, acc_mode) vfs_open(path, file) do_dentry_open(file, path->dentry->d_inode, open) security_file_open(f) open() /* old location of path_noexec() test */ Link: http://lkml.kernel.org/r/20200605160013.3954297-4-keescook@chromium.org Signed-off-by: Kees Cook Cc: Alexander Viro Cc: Aleksa Sarai Cc: Christian Brauner Cc: Dmitry Vyukov Cc: Eric Biggers Cc: Tetsuo Handa Signed-off-by: Andrew Morton --- fs/exec.c | 12 ++++-------- fs/namei.c | 4 ++++ 2 files changed, 8 insertions(+), 8 deletions(-) --- a/fs/exec.c~exec-move-path_noexec-check-earlier +++ a/fs/exec.c @@ -147,10 +147,8 @@ SYSCALL_DEFINE1(uselib, const char __use * and check again at the very end too. */ error = -EACCES; - if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode))) - goto exit; - - if (path_noexec(&file->f_path)) + if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) || + path_noexec(&file->f_path))) goto exit; fsnotify_open(file); @@ -897,10 +895,8 @@ static struct file *do_open_execat(int f * and check again at the very end too. */ err = -EACCES; - if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode))) - goto exit;