xfs: fix missing check for invalid attr flags

The xattr scrubber doesn't check for undefined flags in shortform attr
entries.  Therefore, define a mask XFS_ATTR_ONDISK_MASK that has all
possible XFS_ATTR_* flags in it, and use that to check for unknown bits
in xchk_xattr_actor.

Refactor the check in the dabtree scanner function to use the new mask
as well.  The redundant checks need to be in place because the dabtree
check examines the hash mappings and therefore needs to decode the attr
leaf entries to compute the namehash.  This happens before the walk of
the xattr entries themselves.

Fixes: ae0506eb ("xfs: check used space of shortform xattr structures")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/libxfs/xfs_da_format.h

@@ -719,8 +719,13 @@ struct xfs_attr3_leafblock {
 #define XFS_ATTR_ROOT		(1u << XFS_ATTR_ROOT_BIT)
 #define XFS_ATTR_SECURE		(1u << XFS_ATTR_SECURE_BIT)
 #define XFS_ATTR_INCOMPLETE	(1u << XFS_ATTR_INCOMPLETE_BIT)
+
 #define XFS_ATTR_NSP_ONDISK_MASK	(XFS_ATTR_ROOT | XFS_ATTR_SECURE)
 
+#define XFS_ATTR_ONDISK_MASK	(XFS_ATTR_NSP_ONDISK_MASK | \
+				 XFS_ATTR_LOCAL | \
+				 XFS_ATTR_INCOMPLETE)
+
 #define XFS_ATTR_NAMESPACE_STR \
 	{ XFS_ATTR_LOCAL,	"local" }, \
 	{ XFS_ATTR_ROOT,	"root" }, \

fs/xfs/scrub/attr.c

@@ -192,6 +192,11 @@ xchk_xattr_actor(
 	if (xchk_should_terminate(sc, &error))
 		return error;
 
+	if (attr_flags & ~XFS_ATTR_ONDISK_MASK) {
+		xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, args.blkno);
+		return -ECANCELED;
+	}
+
 	if (attr_flags & XFS_ATTR_INCOMPLETE) {
 		/* Incomplete attr key, just mark the inode for preening. */
 		xchk_ino_set_preen(sc, ip->i_ino);
@@ -481,7 +486,6 @@ xchk_xattr_rec(
 	xfs_dahash_t			hash;
 	int				nameidx;
 	int				hdrsize;
-	unsigned int			badflags;
 	int				error;
 
 	ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
@@ -511,10 +515,11 @@ xchk_xattr_rec(
 
 	/* Retrieve the entry and check it. */
 	hash = be32_to_cpu(ent->hashval);
-	badflags = ~(XFS_ATTR_LOCAL | XFS_ATTR_ROOT | XFS_ATTR_SECURE |
-			XFS_ATTR_INCOMPLETE);
-	if ((ent->flags & badflags) != 0)
+	if (ent->flags & ~XFS_ATTR_ONDISK_MASK) {
 		xchk_da_set_corrupt(ds, level);
+		return 0;
+	}
+
 	if (ent->flags & XFS_ATTR_LOCAL) {
 		lentry = (struct xfs_attr_leaf_name_local *)
 				(((char *)bp->b_addr) + nameidx);