Re: [PATCH v8 6/7] xfs: add capability check to free eofblocks ioctl

Brian Foster
2013-08-01T16:22:20Z

On 08/01/2013 11:30 AM, Dwight Engen wrote:
> 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.
>
> Signed-off-by: Dwight Engen <dwight.engen@oracle.com>
> ---

Thanks Dwight!

Reviewed-by: Brian Foster <bfoster@redhat.com>

> 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 60d9d1e..c8f3511 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -1620,6 +1620,12 @@ xfs_file_ioctl(
> struct xfs_fs_eofblocks eofb;
> struct xfs_eofblocks keofb;
>
> + 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);