From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2FC7C2BA19 for ; Wed, 15 Apr 2020 17:49:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D48FC20787 for ; Wed, 15 Apr 2020 17:49:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2411503AbgDORtB (ORCPT ); Wed, 15 Apr 2020 13:49:01 -0400 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:55500 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2411490AbgDORsw (ORCPT ); Wed, 15 Apr 2020 13:48:52 -0400 Received: from callcc.thunk.org (pool-72-93-95-157.bstnma.fios.verizon.net [72.93.95.157]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 03FHmhwq010256 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 15 Apr 2020 13:48:44 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id 9491A42013D; Wed, 15 Apr 2020 13:48:43 -0400 (EDT) From: "Theodore Ts'o" To: Ext4 Developers List Cc: syzkaller-bugs@googlegroups.com, "Theodore Ts'o" , stable@kernel.org, syzbot+bca9799bf129256190da@syzkaller.appspotmail.com Subject: [PATCH] ext4: reject mount options not supported when remounting in handle_mount_opt() Date: Wed, 15 Apr 2020 13:48:39 -0400 Message-Id: <20200415174839.461347-1-tytso@mit.edu> X-Mailer: git-send-email 2.24.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org Rejecting the mount options in ext4_remount() means that some mount options would be enabled for a small amount of time, and then the mount option change would be reverted. In the case of "mount -o remount,dax", this can cause a race where files would temporarily treated as DAX --- and then not. Cc: stable@kernel.org Reported-and-tested-by: syzbot+bca9799bf129256190da@syzkaller.appspotmail.com Signed-off-by: Theodore Ts'o --- fs/ext4/super.c | 37 +++++++++++-------------------------- 1 file changed, 11 insertions(+), 26 deletions(-) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index bf5fcb477f66..6fe32f9aa889 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -1726,6 +1726,7 @@ static int clear_qf_name(struct super_block *sb, int qtype) #define MOPT_NO_EXT3 0x0200 #define MOPT_EXT4_ONLY (MOPT_NO_EXT2 | MOPT_NO_EXT3) #define MOPT_STRING 0x0400 +#define MOPT_NO_REMOUNT 0x0800 static const struct mount_opts { int token; @@ -1775,12 +1776,12 @@ static const struct mount_opts { {Opt_min_batch_time, 0, MOPT_GTE0}, {Opt_inode_readahead_blks, 0, MOPT_GTE0}, {Opt_init_itable, 0, MOPT_GTE0}, - {Opt_dax, EXT4_MOUNT_DAX, MOPT_SET}, + {Opt_dax, EXT4_MOUNT_DAX, MOPT_SET | MOPT_NO_REMOUNT}, {Opt_stripe, 0, MOPT_GTE0}, {Opt_resuid, 0, MOPT_GTE0}, {Opt_resgid, 0, MOPT_GTE0}, - {Opt_journal_dev, 0, MOPT_NO_EXT2 | MOPT_GTE0}, - {Opt_journal_path, 0, MOPT_NO_EXT2 | MOPT_STRING}, + {Opt_journal_dev, 0, MOPT_NO_EXT2 | MOPT_GTE0 | MOPT_NO_REMOUNT}, + {Opt_journal_path, 0, MOPT_NO_EXT2 | MOPT_STRING | MOPT_NO_REMOUNT}, {Opt_journal_ioprio, 0, MOPT_NO_EXT2 | MOPT_GTE0}, {Opt_data_journal, EXT4_MOUNT_JOURNAL_DATA, MOPT_NO_EXT2 | MOPT_DATAJ}, {Opt_data_ordered, EXT4_MOUNT_ORDERED_DATA, MOPT_NO_EXT2 | MOPT_DATAJ}, @@ -1817,7 +1818,7 @@ static const struct mount_opts { {Opt_jqfmt_vfsv1, QFMT_VFS_V1, MOPT_QFMT}, {Opt_max_dir_size_kb, 0, MOPT_GTE0}, {Opt_test_dummy_encryption, 0, MOPT_GTE0}, - {Opt_nombcache, EXT4_MOUNT_NO_MBCACHE, MOPT_SET}, + {Opt_nombcache, EXT4_MOUNT_NO_MBCACHE, MOPT_SET | MOPT_NO_REMOUNT}, {Opt_err, 0, 0} }; @@ -1915,6 +1916,12 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token, "Mount option \"%s\" incompatible with ext3", opt); return -1; } + if ((m->flags & MOPT_NO_REMOUNT) && is_remount) { + ext4_msg(sb, KERN_ERR, + "Mount option \"%s\" not supported when remounting", + opt); + return -1; + } if (args->from && !(m->flags & MOPT_STRING) && match_int(args, &arg)) return -1; @@ -1994,11 +2001,6 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token, } sbi->s_resgid = gid; } else if (token == Opt_journal_dev) { - if (is_remount) { - ext4_msg(sb, KERN_ERR, - "Cannot specify journal on remount"); - return -1; - } *journal_devnum = arg; } else if (token == Opt_journal_path) { char *journal_path; @@ -2006,11 +2008,6 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token, struct path path; int error; - if (is_remount) { - ext4_msg(sb, KERN_ERR, - "Cannot specify journal on remount"); - return -1; - } journal_path = match_strdup(&args[0]); if (!journal_path) { ext4_msg(sb, KERN_ERR, "error: could not dup " @@ -5427,18 +5424,6 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data) } } - if ((sbi->s_mount_opt ^ old_opts.s_mount_opt) & EXT4_MOUNT_NO_MBCACHE) { - ext4_msg(sb, KERN_ERR, "can't enable nombcache during remount"); - err = -EINVAL; - goto restore_opts; - } - - if ((sbi->s_mount_opt ^ old_opts.s_mount_opt) & EXT4_MOUNT_DAX) { - ext4_msg(sb, KERN_WARNING, "warning: refusing change of " - "dax flag with busy inodes while remounting"); - sbi->s_mount_opt ^= EXT4_MOUNT_DAX; - } - if (sbi->s_mount_flags & EXT4_MF_FS_ABORTED) ext4_abort(sb, EXT4_ERR_ESHUTDOWN, "Abort forced by user"); -- 2.24.1