[PATCH 3.8 01/91] xfs: add capability check to free eofblocks ioctl

From: Kamal Mostafa
Date: Thu Jan 02 2014 - 12:05:32 EST -stable review patch. If anyone has any objections, please let me know.


From: Dwight Engen <dwight.engen@xxxxxxxxxx>

commit 8c567a7fab6e086a0284eee2db82348521e7120c upstream.

Check for CAP_SYS_ADMIN since the caller can truncate preallocated
blocks from files they do not own nor have write access to. A more
fine grained access check was considered: require the caller to
specify their own uid/gid and to use inode_permission to check for
write, but this would not catch the case of an inode not reachable
via path traversal from the callers mount namespace.

Add check for read-only filesystem to free eofblocks ioctl.

Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>
Reviewed-by: Gao feng <gaofeng@xxxxxxxxxxxxxx>
Signed-off-by: Dwight Engen <dwight.engen@xxxxxxxxxx>
Signed-off-by: Ben Myers <bpm@xxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
fs/xfs/xfs_ioctl.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index c1c3ef8..2fe3eb3 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1606,6 +1606,12 @@ xfs_file_ioctl(
struct xfs_eofblocks eofb;

+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ if (mp->m_flags & XFS_MOUNT_RDONLY)
+ return -XFS_ERROR(EROFS);
if (copy_from_user(&eofb, arg, sizeof(eofb)))


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