Commit bb6cdd55 authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

xfs: hide metadata inodes from everyone because they are special 



Metadata inodes are private files and therefore cannot be exposed to
userspace.  This means no bulkstat, no open-by-handle, no linking them
into the directory tree, and no feeding them to LSMs.  As such, we mark
them S_PRIVATE, which stops all that.

Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent 8651b410

fs/xfs/scrub/tempfile.c

+8 −0
Original line number Diff line number Diff line
@@ -844,6 +844,14 @@ xrep_is_tempfile( 
	const struct xfs_inode	*ip)

{

	const struct inode	*inode = &ip->i_vnode;

	struct xfs_mount	*mp = ip->i_mount;



	/*

	 * Files in the metadata directory tree also have S_PRIVATE set and

	 * IOP_XATTR unset, so we must distinguish them separately.

	 */

	if (xfs_has_metadir(mp) && (ip->i_diflags2 & XFS_DIFLAG2_METADATA))

		return false;



	if (IS_PRIVATE(inode) && !(inode->i_opflags & IOP_XATTR))

		return true;

fs/xfs/xfs_iops.c

+14 −1
Original line number Diff line number Diff line
@@ -42,7 +42,9 @@ 
 * held. For regular files, the lock order is the other way around - the

 * mmap_lock is taken during the page fault, and then we lock the ilock to do

 * block mapping. Hence we need a different class for the directory ilock so

 * that lockdep can tell them apart.

 * that lockdep can tell them apart.  Directories in the metadata directory

 * tree get a separate class so that lockdep reports will warn us if someone

 * ever tries to lock regular directories after locking metadata directories.

 */

static struct lock_class_key xfs_nondir_ilock_class;

static struct lock_class_key xfs_dir_ilock_class;
@@ -1289,6 +1291,7 @@ xfs_setup_inode( 
{

	struct inode		*inode = &ip->i_vnode;

	gfp_t			gfp_mask;

	bool			is_meta = xfs_is_internal_inode(ip);



	inode->i_ino = ip->i_ino;

	inode->i_state |= I_NEW;
@@ -1300,6 +1303,16 @@ xfs_setup_inode( 
	i_size_write(inode, ip->i_disk_size);

	xfs_diflags_to_iflags(ip, true);



	/*

	 * Mark our metadata files as private so that LSMs and the ACL code

	 * don't try to add their own metadata or reason about these files,

	 * and users cannot ever obtain file handles to them.

	 */

	if (is_meta) {

		inode->i_flags |= S_PRIVATE;

		inode->i_opflags &= ~IOP_XATTR;

	}



	if (S_ISDIR(inode->i_mode)) {

		/*

		 * We set the i_rwsem class here to avoid potential races with