btrfs: tree-checker: Add checker for dir item

Add checker for dir item, for key types DIR_ITEM, DIR_INDEX and
XATTR_ITEM.

This checker does comprehensive checks for:

1) dir_item header and its data size
   Against item boundary and maximum name/xattr length.
   This part is mostly the same as old verify_dir_item().

2) dir_type
   Against maximum file types, and against key type.
   Since XATTR key should only have FT_XATTR dir item, and normal dir
   item type should not have XATTR key.

   The check between key->type and dir_type is newly introduced by this
   patch.

3) name hash
   For XATTR and DIR_ITEM key, key->offset is name hash (crc32c).
   Check the hash of the name against the key to ensure it's correct.

   The name hash check is only found in btrfs-progs before this patch.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Su Yue <suy.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index ce4ed6ec8f39276c7c7a5d3551b043a9fd8c08b4..66dac0a4b01f320be925316b46acd18761866258 100644 (file)
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -30,6 +30,7 @@
 #include "tree-checker.h"
 #include "disk-io.h"
 #include "compression.h"
+#include "hash.h"
 
 /*
  * Error message should follow the following format:
@@ -222,6 +223,141 @@ static int check_csum_item(struct btrfs_root *root, struct extent_buffer *leaf,
        return 0;
 }
 
+/*
+ * Customized reported for dir_item, only important new info is key->objectid,
+ * which represents inode number
+ */
+__printf(4, 5)
+static void dir_item_err(const struct btrfs_root *root,
+                        const struct extent_buffer *eb, int slot,
+                        const char *fmt, ...)
+{
+       struct btrfs_key key;
+       struct va_format vaf;
+       va_list args;
+
+       btrfs_item_key_to_cpu(eb, &key, slot);
+       va_start(args, fmt);
+
+       vaf.fmt = fmt;
+       vaf.va = &args;
+
+       btrfs_crit(root->fs_info,
+       "corrupt %s: root=%llu block=%llu slot=%d ino=%llu, %pV",
+               btrfs_header_level(eb) == 0 ? "leaf" : "node", root->objectid,
+               btrfs_header_bytenr(eb), slot, key.objectid, &vaf);
+       va_end(args);
+}
+
+static int check_dir_item(struct btrfs_root *root,
+                         struct extent_buffer *leaf,
+                         struct btrfs_key *key, int slot)
+{
+       struct btrfs_dir_item *di;
+       u32 item_size = btrfs_item_size_nr(leaf, slot);
+       u32 cur = 0;
+
+       di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
+       while (cur < item_size) {
+               char namebuf[max(BTRFS_NAME_LEN, XATTR_NAME_MAX)];
+               u32 name_len;
+               u32 data_len;
+               u32 max_name_len;
+               u32 total_size;
+               u32 name_hash;
+               u8 dir_type;
+
+               /* header itself should not cross item boundary */
+               if (cur + sizeof(*di) > item_size) {
+                       dir_item_err(root, leaf, slot,
+               "dir item header crosses item boundary, have %lu boundary %u",
+                               cur + sizeof(*di), item_size);
+                       return -EUCLEAN;
+               }
+
+               /* dir type check */
+               dir_type = btrfs_dir_type(leaf, di);
+               if (dir_type >= BTRFS_FT_MAX) {
+                       dir_item_err(root, leaf, slot,
+                       "invalid dir item type, have %u expect [0, %u)",
+                               dir_type, BTRFS_FT_MAX);
+                       return -EUCLEAN;
+               }
+
+               if (key->type == BTRFS_XATTR_ITEM_KEY &&
+                   dir_type != BTRFS_FT_XATTR) {
+                       dir_item_err(root, leaf, slot,
+               "invalid dir item type for XATTR key, have %u expect %u",
+                               dir_type, BTRFS_FT_XATTR);
+                       return -EUCLEAN;
+               }
+               if (dir_type == BTRFS_FT_XATTR &&
+                   key->type != BTRFS_XATTR_ITEM_KEY) {
+                       dir_item_err(root, leaf, slot,
+                       "xattr dir type found for non-XATTR key");
+                       return -EUCLEAN;
+               }
+               if (dir_type == BTRFS_FT_XATTR)
+                       max_name_len = XATTR_NAME_MAX;
+               else
+                       max_name_len = BTRFS_NAME_LEN;
+
+               /* Name/data length check */
+               name_len = btrfs_dir_name_len(leaf, di);
+               data_len = btrfs_dir_data_len(leaf, di);
+               if (name_len > max_name_len) {
+                       dir_item_err(root, leaf, slot,
+                       "dir item name len too long, have %u max %u",
+                               name_len, max_name_len);
+                       return -EUCLEAN;
+               }
+               if (name_len + data_len > BTRFS_MAX_XATTR_SIZE(root->fs_info)) {
+                       dir_item_err(root, leaf, slot,
+                       "dir item name and data len too long, have %u max %u",
+                               name_len + data_len,
+                               BTRFS_MAX_XATTR_SIZE(root->fs_info));
+                       return -EUCLEAN;
+               }
+
+               if (data_len && dir_type != BTRFS_FT_XATTR) {
+                       dir_item_err(root, leaf, slot,
+                       "dir item with invalid data len, have %u expect 0",
+                               data_len);
+                       return -EUCLEAN;
+               }
+
+               total_size = sizeof(*di) + name_len + data_len;
+
+               /* header and name/data should not cross item boundary */
+               if (cur + total_size > item_size) {
+                       dir_item_err(root, leaf, slot,
+               "dir item data crosses item boundary, have %u boundary %u",
+                               cur + total_size, item_size);
+                       return -EUCLEAN;
+               }
+
+               /*
+                * Special check for XATTR/DIR_ITEM, as key->offset is name
+                * hash, should match its name
+                */
+               if (key->type == BTRFS_DIR_ITEM_KEY ||
+                   key->type == BTRFS_XATTR_ITEM_KEY) {
+                       read_extent_buffer(leaf, namebuf,
+                                       (unsigned long)(di + 1), name_len);
+                       name_hash = btrfs_name_hash(namebuf, name_len);
+                       if (key->offset != name_hash) {
+                               dir_item_err(root, leaf, slot,
+               "name hash mismatch with key, have 0x%016x expect 0x%016llx",
+                                       name_hash, key->offset);
+                               return -EUCLEAN;
+                       }
+               }
+               cur += total_size;
+               di = (struct btrfs_dir_item *)((void *)di + total_size);
+       }
+       return 0;
+}
+
 /*
  * Common point to switch the item-specific validation.
  */
@@ -238,6 +374,11 @@ static int check_leaf_item(struct btrfs_root *root,
        case BTRFS_EXTENT_CSUM_KEY:
                ret = check_csum_item(root, leaf, key, slot);
                break;
+       case BTRFS_DIR_ITEM_KEY:
+       case BTRFS_DIR_INDEX_KEY:
+       case BTRFS_XATTR_ITEM_KEY:
+               ret = check_dir_item(root, leaf, key, slot);
+               break;
        }
        return ret;
 }