From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:52537 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752970AbbIZR0c (ORCPT ); Sat, 26 Sep 2015 13:26:32 -0400 Subject: Patch "fs: Don't dump core if the corefile would become world-readable." has been added to the 4.1-stable tree To: jann@thejh.net, akpm@linux-foundation.org, gregkh@linuxfoundation.org, keescook@chromium.org, torvalds@linux-foundation.org, viro@zeniv.linux.org.uk Cc: , From: Date: Sat, 26 Sep 2015 10:26:31 -0700 Message-ID: <1443288391155252@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled fs: Don't dump core if the corefile would become world-readable. to the 4.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: fs-don-t-dump-core-if-the-corefile-would-become-world-readable.patch and it can be found in the queue-4.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 40f705a736eac10e7dca7ab5dd5ed675a6df031d Mon Sep 17 00:00:00 2001 From: Jann Horn Date: Wed, 9 Sep 2015 15:38:30 -0700 Subject: fs: Don't dump core if the corefile would become world-readable. From: Jann Horn commit 40f705a736eac10e7dca7ab5dd5ed675a6df031d upstream. On a filesystem like vfat, all files are created with the same owner and mode independent of who created the file. When a vfat filesystem is mounted with root as owner of all files and read access for everyone, root's processes left world-readable coredumps on it (but other users' processes only left empty corefiles when given write access because of the uid mismatch). Given that the old behavior was inconsistent and insecure, I don't see a problem with changing it. Now, all processes refuse to dump core unless the resulting corefile will only be readable by their owner. Signed-off-by: Jann Horn Acked-by: Kees Cook Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/coredump.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/fs/coredump.c +++ b/fs/coredump.c @@ -678,11 +678,15 @@ void do_coredump(const siginfo_t *siginf if (!S_ISREG(inode->i_mode)) goto close_fail; /* - * Dont allow local users get cute and trick others to coredump - * into their pre-created files. + * Don't dump core if the filesystem changed owner or mode + * of the file during file creation. This is an issue when + * a process dumps core while its cwd is e.g. on a vfat + * filesystem. */ if (!uid_eq(inode->i_uid, current_fsuid())) goto close_fail; + if ((inode->i_mode & 0677) != 0600) + goto close_fail; if (!(cprm.file->f_mode & FMODE_CAN_WRITE)) goto close_fail; if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file)) Patches currently in stable-queue which might be from jann@thejh.net are queue-4.1/fs-if-a-coredump-already-exists-unlink-and-recreate-with-o_excl.patch queue-4.1/fs-don-t-dump-core-if-the-corefile-would-become-world-readable.patch queue-4.1/cifs-fix-type-confusion-in-copy-offload-ioctl.patch