[PATCH 3.12 61/83] xfs: add capability check to free eofblocks ioctl

Greg Kroah-Hartman
2013-12-06T22:29:11Z

From: Dwight Engen <dwight.engen@oracle.com>

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@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Dwight Engen <dwight.engen@oracle.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
Cc: Kees Cook <keescook@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/xfs/xfs_ioctl.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1717,6 +1717,12 @@ xfs_file_ioctl(
if (mp->m_flags & XFS_MOUNT_RDONLY)
return -XFS_ERROR(EROFS);

+ 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)))
return -XFS_ERROR(EFAULT);