From: Marco Stornelli Subject: [PATCH] Check for immutable flag in fallocate path Date: Mon, 21 Feb 2011 09:26:32 +0100 Message-ID: <4D6221B8.9040303@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, cluster-devel@redhat.com, xfs@oss.sgi.com, Linux FS Devel To: Linux Kernel Return-path: Received: from mail-wy0-f174.google.com ([74.125.82.174]:53789 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752189Ab1BUIba (ORCPT ); Mon, 21 Feb 2011 03:31:30 -0500 Sender: linux-ext4-owner@vger.kernel.org List-ID: From: Marco Stornelli All fs must check for the immutable flag in their fallocate callback. It's possible to have a race condition in this scenario: an application open a file in read/write and it does something, meanwhile root set the immutable flag on the file, the application at that point can call fallocate with success. Only Ocfs2 check for the immutable flag at the moment. Signed-off-by: Marco Stornelli --- Patch is against 2.6.38-rc5 --- linux-2.6.38-rc5-orig/fs/ext4/extents.c 2011-02-16 04:23:45.000000000 +0100 +++ linux-2.6.38-rc5/fs/ext4/extents.c 2011-02-21 08:43:37.000000000 +0100 @@ -3670,6 +3670,12 @@ long ext4_fallocate(struct file *file, i */ credits = ext4_chunk_trans_blocks(inode, max_blocks); mutex_lock(&inode->i_mutex); + + if (IS_IMMUTABLE(inode)) { + mutex_unlock(&inode->i_mutex); + return -EPERM; + } + ret = inode_newsize_ok(inode, (len + offset)); if (ret) { mutex_unlock(&inode->i_mutex); --- linux-2.6.38-rc5-orig/fs/btrfs/file.c 2011-02-16 04:23:45.000000000 +0100 +++ linux-2.6.38-rc5/fs/btrfs/file.c 2011-02-21 08:55:58.000000000 +0100 @@ -1289,6 +1289,12 @@ static long btrfs_fallocate(struct file btrfs_wait_ordered_range(inode, alloc_start, alloc_end - alloc_start); mutex_lock(&inode->i_mutex); + + if (IS_IMMUTABLE(inode)) { + ret = -EPERM; + goto out; + } + ret = inode_newsize_ok(inode, alloc_end); if (ret) goto out; --- linux-2.6.38-rc5-orig/fs/xfs/linux-2.6/xfs_file.c 2011-02-16 04:23:45.000000000 +0100 +++ linux-2.6.38-rc5/fs/xfs/linux-2.6/xfs_file.c 2011-02-21 09:07:46.000000000 +0100 @@ -909,6 +909,11 @@ xfs_file_fallocate( if (mode & FALLOC_FL_PUNCH_HOLE) cmd = XFS_IOC_UNRESVSP; + if (IS_IMMUTABLE(inode)) { + error = -EPERM; + goto out_unlock; + } + /* check the new inode size is valid before allocating */ if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > i_size_read(inode)) { --- linux-2.6.38-rc5-orig/fs/gfs2/file.c 2011-02-16 04:23:45.000000000 +0100 +++ linux-2.6.38-rc5/fs/gfs2/file.c 2011-02-21 09:09:17.000000000 +0100 @@ -797,6 +797,11 @@ static long gfs2_fallocate(struct file * if (unlikely(error)) goto out_uninit; + if (IS_IMMUTABLE(inode)) { + error = -EPERM; + goto out_unlock; + } + if (!gfs2_write_alloc_required(ip, offset, len)) goto out_unlock;