Btrfs: add checks to verify dir items are correct

We need to make sure the dir items we get are valid dir items.  So any time we
try and read one check it with verify_dir_item, which will do various sanity
checks to make sure it looks sane.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>

5 files changed, 50 insertions, 0 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 841330f3d68..6036fdb88c5 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2393,6 +2393,9 @@ struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
 					  struct btrfs_path *path, u64 dir,
 					  const char *name, u16 name_len,
 					  int mod);
+int verify_dir_item(struct btrfs_root *root,
+		    struct extent_buffer *leaf,
+		    struct btrfs_dir_item *dir_item);
 
 /* orphan.c */
 int btrfs_insert_orphan_item(struct btrfs_trans_handle *trans,
diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
index f0cad5ae5be..02c97ad61b6 100644
--- a/fs/btrfs/dir-item.c
+++ b/fs/btrfs/dir-item.c
@@ -377,6 +377,9 @@ struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_root *root,
 
 	leaf = path->nodes[0];
 	dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
+	if (verify_dir_item(root, leaf, dir_item))
+		return NULL;
+
 	total_len = btrfs_item_size_nr(leaf, path->slots[0]);
 	while (cur < total_len) {
 		this_len = sizeof(*dir_item) +
@@ -429,3 +432,35 @@ int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
 	}
 	return ret;
 }
+
+int verify_dir_item(struct btrfs_root *root,
+		    struct extent_buffer *leaf,
+		    struct btrfs_dir_item *dir_item)
+{
+	u16 namelen = BTRFS_NAME_LEN;
+	u8 type = btrfs_dir_type(leaf, dir_item);
+
+	if (type >= BTRFS_FT_MAX) {
+		printk(KERN_CRIT "btrfs: invalid dir item type: %d\n",
+		       (int)type);
+		return 1;
+	}
+
+	if (type == BTRFS_FT_XATTR)
+		namelen = XATTR_NAME_MAX;
+
+	if (btrfs_dir_name_len(leaf, dir_item) > namelen) {
+		printk(KERN_CRIT "btrfS: invalid dir item name len: %u\n",
+		       (unsigned)btrfs_dir_data_len(leaf, dir_item));
+		return 1;
+	}
+
+	/* BTRFS_MAX_XATTR_SIZE is the same for all dir items */
+	if (btrfs_dir_data_len(leaf, dir_item) > BTRFS_MAX_XATTR_SIZE(root)) {
+		printk(KERN_CRIT "btrfs: invalid dir item data len: %u\n",
+		       (unsigned)btrfs_dir_data_len(leaf, dir_item));
+		return 1;
+	}
+
+	return 0;
+}
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 888dbdb3b12..e010000d4bc 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4272,6 +4272,9 @@ static int btrfs_real_readdir(struct file *filp, void *dirent,
 		while (di_cur < di_total) {
 			struct btrfs_key location;
 
+			if (verify_dir_item(root, leaf, di))
+				break;
+
 			name_len = btrfs_dir_name_len(leaf, di);
 			if (name_len <= sizeof(tmp_name)) {
 				name_ptr = tmp_name;
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index a4bbb854dfd..429cfcfadf9 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -1286,6 +1286,8 @@ static noinline int replay_one_dir_item(struct btrfs_trans_handle *trans,
 	ptr_end = ptr + item_size;
 	while (ptr < ptr_end) {
 		di = (struct btrfs_dir_item *)ptr;
+		if (verify_dir_item(root, eb, di))
+			return -EIO;
 		name_len = btrfs_dir_name_len(eb, di);
 		ret = replay_one_name(trans, root, path, eb, di, key);
 		BUG_ON(ret);
@@ -1412,6 +1414,11 @@ again:
 	ptr_end = ptr + item_size;
 	while (ptr < ptr_end) {
 		di = (struct btrfs_dir_item *)ptr;
+		if (verify_dir_item(root, eb, di)) {
+			ret = -EIO;
+			goto out;
+		}
+
 		name_len = btrfs_dir_name_len(eb, di);
 		name = kmalloc(name_len, GFP_NOFS);
 		if (!name) {
diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index a5776531dc2..e5d22f28095 100644
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -242,6 +242,8 @@ ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
 			break;
 
 		di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
+		if (verify_dir_item(root, leaf, di))
+			continue;
 
 		name_len = btrfs_dir_name_len(leaf, di);
 		total_size += name_len + 1;