xfs: enforce metadata inode flag

Add checks for the metadata inode flag so that we don't ever leak
metadata inodes out to userspace, and we don't ever try to read a
regular inode as metadata.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

1 files changed, 11 insertions, 0 deletions

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 12c5ff151edf..ae94583ea3bb 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -555,8 +555,19 @@ xfs_lookup(
 	if (error)
 		goto out_free_name;
 
+	/*
+	 * Fail if a directory entry in the regular directory tree points to
+	 * a metadata file.
+	 */
+	if (XFS_IS_CORRUPT(dp->i_mount, xfs_is_metadir_inode(*ipp))) {
+		error = -EFSCORRUPTED;
+		goto out_irele;
+	}
+
 	return 0;
 
+out_irele:
+	xfs_irele(*ipp);
 out_free_name:
 	if (ci_name)
 		kfree(ci_name->name);