xfs: enforce one namespace per attribute

Create a standardized helper function to enforce one namespace bit per
extended attribute, and refactor all the open-coded hweight logic.  This
function is not a static inline to avoid porting hassles in userspace.

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

fs/xfs/libxfs/xfs_attr.c

@@ -1532,12 +1532,23 @@ out_release:
 	return error;
 }
 
+/* Enforce that there is at most one namespace bit per attr. */
+inline bool xfs_attr_check_namespace(unsigned int attr_flags)
+{
+	return hweight32(attr_flags & XFS_ATTR_NSP_ONDISK_MASK) < 2;
+}
+
 /* Returns true if the attribute entry name is valid. */
 bool
 xfs_attr_namecheck(
+	unsigned int	attr_flags,
 	const void	*name,
 	size_t		length)
 {
+	/* Only one namespace bit allowed. */
+	if (!xfs_attr_check_namespace(attr_flags))
+		return false;
+
 	/*
 	 * MAXNAMELEN includes the trailing null, but (name/length) leave it
 	 * out, so use >= for the length check.

fs/xfs/libxfs/xfs_attr.h

@@ -560,7 +560,9 @@ enum xfs_attr_update {
 int xfs_attr_set(struct xfs_da_args *args, enum xfs_attr_update op);
 int xfs_attr_set_iter(struct xfs_attr_intent *attr);
 int xfs_attr_remove_iter(struct xfs_attr_intent *attr);
-bool xfs_attr_namecheck(const void *name, size_t length);
+bool xfs_attr_check_namespace(unsigned int attr_flags);
+bool xfs_attr_namecheck(unsigned int attr_flags, const void *name,
+		size_t length);
 int xfs_attr_calc_size(struct xfs_da_args *args, int *local);
 void xfs_init_attr_trans(struct xfs_da_args *args, struct xfs_trans_res *tres,
 			 unsigned int *total);

fs/xfs/libxfs/xfs_attr_leaf.c

@@ -950,6 +950,11 @@ xfs_attr_shortform_to_leaf(
 		nargs.hashval = xfs_da_hashname(sfe->nameval,
 						sfe->namelen);
 		nargs.attr_filter = sfe->flags & XFS_ATTR_NSP_ONDISK_MASK;
+		if (!xfs_attr_check_namespace(sfe->flags)) {
+			xfs_da_mark_sick(args);
+			error = -EFSCORRUPTED;
+			goto out;
+		}
 		error = xfs_attr3_leaf_lookup_int(bp, &nargs); /* set a->index */
 		ASSERT(error == -ENOATTR);
 		error = xfs_attr3_leaf_add(bp, &nargs);
@@ -1063,7 +1068,7 @@ xfs_attr_shortform_verify(
 		 * one namespace flag per xattr, so we can just count the
 		 * bits (i.e. hweight) here.
 		 */
-		if (hweight8(sfep->flags & XFS_ATTR_NSP_ONDISK_MASK) > 1)
+		if (!xfs_attr_check_namespace(sfep->flags))
 			return __this_address;
 
 		sfep = next_sfep;

fs/xfs/scrub/attr.c

@@ -203,14 +203,8 @@ xchk_xattr_actor(
 		return 0;
 	}
 
-	/* Only one namespace bit allowed. */
-	if (hweight32(attr_flags & XFS_ATTR_NSP_ONDISK_MASK) > 1) {
-		xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, args.blkno);
-		return -ECANCELED;
-	}
-
 	/* Does this name make sense? */
-	if (!xfs_attr_namecheck(name, namelen)) {
+	if (!xfs_attr_namecheck(attr_flags, name, namelen)) {
 		xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, args.blkno);
 		return -ECANCELED;
 	}
@@ -519,6 +513,10 @@ xchk_xattr_rec(
 		xchk_da_set_corrupt(ds, level);
 		return 0;
 	}
+	if (!xfs_attr_check_namespace(ent->flags)) {
+		xchk_da_set_corrupt(ds, level);
+		return 0;
+	}
 
 	if (ent->flags & XFS_ATTR_LOCAL) {
 		lentry = (struct xfs_attr_leaf_name_local *)

fs/xfs/scrub/attr_repair.c

@@ -123,12 +123,10 @@ xrep_xattr_want_salvage(
 		return false;
 	if (namelen > XATTR_NAME_MAX || namelen <= 0)
 		return false;
-	if (!xfs_attr_namecheck(name, namelen))
+	if (!xfs_attr_namecheck(attr_flags, name, namelen))
 		return false;
 	if (valuelen > XATTR_SIZE_MAX || valuelen < 0)
 		return false;
-	if (hweight32(attr_flags & XFS_ATTR_NSP_ONDISK_MASK) > 1)
-		return false;
 	return true;
 }
 

fs/xfs/xfs_attr_item.c

@@ -492,6 +492,10 @@ xfs_attri_validate(
 	if (attrp->alfi_attr_filter & ~XFS_ATTRI_FILTER_MASK)
 		return false;
 
+	if (!xfs_attr_check_namespace(attrp->alfi_attr_filter &
+				      XFS_ATTR_NSP_ONDISK_MASK))
+		return false;
+
 	switch (op) {
 	case XFS_ATTRI_OP_FLAGS_SET:
 	case XFS_ATTRI_OP_FLAGS_REPLACE:
@@ -633,7 +637,8 @@ xfs_attr_recover_work(
 	 */
 	attrp = &attrip->attri_format;
 	if (!xfs_attri_validate(mp, attrp) ||
-	    !xfs_attr_namecheck(nv->name.i_addr, nv->name.i_len))
+	    !xfs_attr_namecheck(attrp->alfi_attr_filter, nv->name.i_addr,
+				nv->name.i_len))
 		return -EFSCORRUPTED;
 
 	attr = xfs_attri_recover_work(mp, dfp, attrp, &ip, nv);
@@ -747,7 +752,8 @@ xfs_attri_validate_name_iovec(
 		return NULL;
 	}
 
-	if (!xfs_attr_namecheck(iovec->i_addr, name_len)) {
+	if (!xfs_attr_namecheck(attri_formatp->alfi_attr_filter, iovec->i_addr,
+				name_len)) {
 		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
 				attri_formatp, sizeof(*attri_formatp));
 		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,

fs/xfs/xfs_attr_list.c

@@ -82,7 +82,8 @@ xfs_attr_shortform_list(
 	     (dp->i_af.if_bytes + sf->count * 16) < context->bufsize)) {
 		for (i = 0, sfe = xfs_attr_sf_firstentry(sf); i < sf->count; i++) {
 			if (XFS_IS_CORRUPT(context->dp->i_mount,
-					   !xfs_attr_namecheck(sfe->nameval,
+					   !xfs_attr_namecheck(sfe->flags,
+							       sfe->nameval,
 							       sfe->namelen))) {
 				xfs_dirattr_mark_sick(context->dp, XFS_ATTR_FORK);
 				return -EFSCORRUPTED;
@@ -122,7 +123,8 @@ xfs_attr_shortform_list(
 	for (i = 0, sfe = xfs_attr_sf_firstentry(sf); i < sf->count; i++) {
 		if (unlikely(
 		    ((char *)sfe < (char *)sf) ||
-		    ((char *)sfe >= ((char *)sf + dp->i_af.if_bytes)))) {
+		    ((char *)sfe >= ((char *)sf + dp->i_af.if_bytes)) ||
+		    !xfs_attr_check_namespace(sfe->flags))) {
 			XFS_CORRUPTION_ERROR("xfs_attr_shortform_list",
 					     XFS_ERRLEVEL_LOW,
 					     context->dp->i_mount, sfe,
@@ -177,7 +179,7 @@ xfs_attr_shortform_list(
 			cursor->offset = 0;
 		}
 		if (XFS_IS_CORRUPT(context->dp->i_mount,
-				   !xfs_attr_namecheck(sbp->name,
+				   !xfs_attr_namecheck(sbp->flags, sbp->name,
 						       sbp->namelen))) {
 			xfs_dirattr_mark_sick(context->dp, XFS_ATTR_FORK);
 			error = -EFSCORRUPTED;
@@ -502,7 +504,8 @@ xfs_attr3_leaf_list_int(
 		}
 
 		if (XFS_IS_CORRUPT(context->dp->i_mount,
-				   !xfs_attr_namecheck(name, namelen))) {
+				   !xfs_attr_namecheck(entry->flags, name,
+						       namelen))) {
 			xfs_dirattr_mark_sick(context->dp, XFS_ATTR_FORK);
 			return -EFSCORRUPTED;
 		}