From: Theodore Ts'o <tytso@mit.edu>
Date: Thu, 3 Jun 2010 02:04:39 +0000 (-0400)
Subject: ext4: Make sure the MOVE_EXT ioctl can't overwrite append-only files
X-Git-Tag: v2.6.34.1~30
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=94f98453eab3c95eaa40132b2e78cc4edc1bf48f;p=users%2Fdwmw2%2Flinux.git

ext4: Make sure the MOVE_EXT ioctl can't overwrite append-only files

commit 1f5a81e41f8b1a782c68d3843e9ec1bfaadf7d72 upstream.

Dan Roseberg has reported a problem with the MOVE_EXT ioctl.  If the
donor file is an append-only file, we should not allow the operation
to proceed, lest we end up overwriting the contents of an append-only
file.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Dan Rosenberg <dan.j.rosenberg@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index d1fc662cc3110..d3d6a649e3a77 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -959,6 +959,9 @@ mext_check_arguments(struct inode *orig_inode,
 		return -EINVAL;
 	}
 
+	if (IS_IMMUTABLE(donor_inode) || IS_APPEND(donor_inode))
+		return -EPERM;
+
 	/* Ext4 move extent does not support swapfile */
 	if (IS_SWAPFILE(orig_inode) || IS_SWAPFILE(donor_inode)) {
 		ext4_debug("ext4 move extent: The argument files should "