Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

Pull overlayfs fixes from Miklos Szeredi:
 "Fix several issues, most of them introduced in the last release"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: do not cleanup unsupported index entries
  ovl: handle ENOENT on index lookup
  ovl: fix EIO from lookup of non-indexed upper
  ovl: Return -ENOMEM if an allocation fails ovl_lookup()
  ovl: add NULL check in ovl_alloc_inode

fs/overlayfs/inode.c

@@ -598,18 +598,30 @@ static bool ovl_verify_inode(struct inode *inode, struct dentry *lowerdentry,
 	return true;
 }
 
-struct inode *ovl_get_inode(struct dentry *dentry, struct dentry *upperdentry)
+struct inode *ovl_get_inode(struct dentry *dentry, struct dentry *upperdentry,
+			    struct dentry *index)
 {
 	struct dentry *lowerdentry = ovl_dentry_lower(dentry);
 	struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL;
 	struct inode *inode;
+	/* Already indexed or could be indexed on copy up? */
+	bool indexed = (index || (ovl_indexdir(dentry->d_sb) && !upperdentry));
+
+	if (WARN_ON(upperdentry && indexed && !lowerdentry))
+		return ERR_PTR(-EIO);
 
 	if (!realinode)
 		realinode = d_inode(lowerdentry);
 
-	if (!S_ISDIR(realinode->i_mode) &&
-	    (upperdentry || (lowerdentry && ovl_indexdir(dentry->d_sb)))) {
-		struct inode *key = d_inode(lowerdentry ?: upperdentry);
+	/*
+	 * Copy up origin (lower) may exist for non-indexed upper, but we must
+	 * not use lower as hash key in that case.
+	 * Hash inodes that are or could be indexed by origin inode and
+	 * non-indexed upper inodes that could be hard linked by upper inode.
+	 */
+	if (!S_ISDIR(realinode->i_mode) && (upperdentry || indexed)) {
+		struct inode *key = d_inode(indexed ? lowerdentry :
+						      upperdentry);
 		unsigned int nlink;
 
 		inode = iget5_locked(dentry->d_sb, (unsigned long) key,

fs/overlayfs/namei.c

@@ -405,14 +405,13 @@ int ovl_verify_index(struct dentry *index, struct path *lowerstack,
 	 * be treated as stale (i.e. after unlink of the overlay inode).
 	 * We don't know the verification rules for directory and whiteout
 	 * index entries, because they have not been implemented yet, so return
-	 * EROFS if those entries are found to avoid corrupting an index that
-	 * was created by a newer kernel.
+	 * EINVAL if those entries are found to abort the mount to avoid
+	 * corrupting an index that was created by a newer kernel.
 	 */
-	err = -EROFS;
+	err = -EINVAL;
 	if (d_is_dir(index) || ovl_is_whiteout(index))
 		goto fail;
 
-	err = -EINVAL;
 	if (index->d_name.len < sizeof(struct ovl_fh)*2)
 		goto fail;
 
@@ -507,6 +506,10 @@ static struct dentry *ovl_lookup_index(struct dentry *dentry,
 	index = lookup_one_len_unlocked(name.name, ofs->indexdir, name.len);
 	if (IS_ERR(index)) {
 		err = PTR_ERR(index);
+		if (err == -ENOENT) {
+			index = NULL;
+			goto out;
+		}
 		pr_warn_ratelimited("overlayfs: failed inode index lookup (ino=%lu, key=%*s, err=%i);\n"
 				    "overlayfs: mount with '-o index=off' to disable inodes index.\n",
 				    d_inode(origin)->i_ino, name.len, name.name,
@@ -516,18 +519,9 @@ static struct dentry *ovl_lookup_index(struct dentry *dentry,
 
 	inode = d_inode(index);
 	if (d_is_negative(index)) {
-		if (upper && d_inode(origin)->i_nlink > 1) {
-			pr_warn_ratelimited("overlayfs: hard link with origin but no index (ino=%lu).\n",
-					    d_inode(origin)->i_ino);
-			goto fail;
-		}
-
-		dput(index);
-		index = NULL;
+		goto out_dput;
 	} else if (upper && d_inode(upper) != inode) {
-		pr_warn_ratelimited("overlayfs: wrong index found (index=%pd2, ino=%lu, upper ino=%lu).\n",
-				    index, inode->i_ino, d_inode(upper)->i_ino);
-		goto fail;
+		goto out_dput;
 	} else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) ||
 		   ((inode->i_mode ^ d_inode(origin)->i_mode) & S_IFMT)) {
 		/*
@@ -547,6 +541,11 @@ static struct dentry *ovl_lookup_index(struct dentry *dentry,
 	kfree(name.name);
 	return index;
 
+out_dput:
+	dput(index);
+	index = NULL;
+	goto out;
+
 fail:
 	dput(index);
 	index = ERR_PTR(-EIO);
@@ -635,6 +634,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 		}
 
 		if (d.redirect) {
+			err = -ENOMEM;
 			upperredirect = kstrdup(d.redirect, GFP_KERNEL);
 			if (!upperredirect)
 				goto out_put_upper;
@@ -709,7 +709,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 		upperdentry = dget(index);
 
 	if (upperdentry || ctr) {
-		inode = ovl_get_inode(dentry, upperdentry);
+		inode = ovl_get_inode(dentry, upperdentry, index);
 		err = PTR_ERR(inode);
 		if (IS_ERR(inode))
 			goto out_free_oe;

fs/overlayfs/overlayfs.h

@@ -286,7 +286,8 @@ int ovl_update_time(struct inode *inode, struct timespec *ts, int flags);
 bool ovl_is_private_xattr(const char *name);
 
 struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev);
-struct inode *ovl_get_inode(struct dentry *dentry, struct dentry *upperdentry);
+struct inode *ovl_get_inode(struct dentry *dentry, struct dentry *upperdentry,
+			    struct dentry *index);
 static inline void ovl_copyattr(struct inode *from, struct inode *to)
 {
 	to->i_uid = from->i_uid;

fs/overlayfs/readdir.c

@@ -1021,13 +1021,12 @@ int ovl_indexdir_cleanup(struct dentry *dentry, struct vfsmount *mnt,
 			break;
 		}
 		err = ovl_verify_index(index, lowerstack, numlower);
-		if (err) {
-			if (err == -EROFS)
-				break;
+		/* Cleanup stale and orphan index entries */
+		if (err && (err == -ESTALE || err == -ENOENT))
 			err = ovl_cleanup(dir, index);
 		if (err)
 			break;
-		}
+
 		dput(index);
 		index = NULL;
 	}

fs/overlayfs/super.c

@@ -174,6 +174,9 @@ static struct inode *ovl_alloc_inode(struct super_block *sb)
 {
 	struct ovl_inode *oi = kmem_cache_alloc(ovl_inode_cachep, GFP_KERNEL);
 
+	if (!oi)
+		return NULL;
+
 	oi->cache = NULL;
 	oi->redirect = NULL;
 	oi->version = 0;