btrfs: tree-checker: Add ROOT_ITEM check

This patch will introduce ROOT_ITEM check, which includes:
- Key->objectid and key->offset check
  Currently only some easy check, e.g. 0 as rootid is invalid.

- Item size check
  Root item size is fixed.

- Generation checks
  Generation, generation_v2 and last_snapshot should not be greater than
  super generation + 1

- Level and alignment check
  Level should be in [0, 7], and bytenr must be aligned to sector size.

- Flags check

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203261
Reported-by: Jungyeon Yoon <jungyeon.yoon@gmail.com>
Signed-off-by: Qu Wenruo <wqu@suse.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 ccd5706199d76da7d0f1db7e900bb69f8fb9bd16..d83adda6c090add56744ac37b9a4702b1ef718ec 100644 (file)
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -821,6 +821,95 @@ static int check_inode_item(struct extent_buffer *leaf,
        return 0;
 }
 
+static int check_root_item(struct extent_buffer *leaf, struct btrfs_key *key,
+                          int slot)
+{
+       struct btrfs_fs_info *fs_info = leaf->fs_info;
+       struct btrfs_root_item ri;
+       const u64 valid_root_flags = BTRFS_ROOT_SUBVOL_RDONLY |
+                                    BTRFS_ROOT_SUBVOL_DEAD;
+
+       /* No such tree id */
+       if (key->objectid == 0) {
+               generic_err(leaf, slot, "invalid root id 0");
+               return -EUCLEAN;
+       }
+
+       /*
+        * Some older kernel may create ROOT_ITEM with non-zero offset, so here
+        * we only check offset for reloc tree whose key->offset must be a
+        * valid tree.
+        */
+       if (key->objectid == BTRFS_TREE_RELOC_OBJECTID && key->offset == 0) {
+               generic_err(leaf, slot, "invalid root id 0 for reloc tree");
+               return -EUCLEAN;
+       }
+
+       if (btrfs_item_size_nr(leaf, slot) != sizeof(ri)) {
+               generic_err(leaf, slot,
+                           "invalid root item size, have %u expect %zu",
+                           btrfs_item_size_nr(leaf, slot), sizeof(ri));
+       }
+
+       read_extent_buffer(leaf, &ri, btrfs_item_ptr_offset(leaf, slot),
+                          sizeof(ri));
+
+       /* Generation related */
+       if (btrfs_root_generation(&ri) >
+           btrfs_super_generation(fs_info->super_copy) + 1) {
+               generic_err(leaf, slot,
+                       "invalid root generation, have %llu expect (0, %llu]",
+                           btrfs_root_generation(&ri),
+                           btrfs_super_generation(fs_info->super_copy) + 1);
+               return -EUCLEAN;
+       }
+       if (btrfs_root_generation_v2(&ri) >
+           btrfs_super_generation(fs_info->super_copy) + 1) {
+               generic_err(leaf, slot,
+               "invalid root v2 generation, have %llu expect (0, %llu]",
+                           btrfs_root_generation_v2(&ri),
+                           btrfs_super_generation(fs_info->super_copy) + 1);
+               return -EUCLEAN;
+       }
+       if (btrfs_root_last_snapshot(&ri) >
+           btrfs_super_generation(fs_info->super_copy) + 1) {
+               generic_err(leaf, slot,
+               "invalid root last_snapshot, have %llu expect (0, %llu]",
+                           btrfs_root_last_snapshot(&ri),
+                           btrfs_super_generation(fs_info->super_copy) + 1);
+               return -EUCLEAN;
+       }
+
+       /* Alignment and level check */
+       if (!IS_ALIGNED(btrfs_root_bytenr(&ri), fs_info->sectorsize)) {
+               generic_err(leaf, slot,
+               "invalid root bytenr, have %llu expect to be aligned to %u",
+                           btrfs_root_bytenr(&ri), fs_info->sectorsize);
+               return -EUCLEAN;
+       }
+       if (btrfs_root_level(&ri) >= BTRFS_MAX_LEVEL) {
+               generic_err(leaf, slot,
+                           "invalid root level, have %u expect [0, %u]",
+                           btrfs_root_level(&ri), BTRFS_MAX_LEVEL - 1);
+               return -EUCLEAN;
+       }
+       if (ri.drop_level >= BTRFS_MAX_LEVEL) {
+               generic_err(leaf, slot,
+                           "invalid root level, have %u expect [0, %u]",
+                           ri.drop_level, BTRFS_MAX_LEVEL - 1);
+               return -EUCLEAN;
+       }
+
+       /* Flags check */
+       if (btrfs_root_flags(&ri) & ~valid_root_flags) {
+               generic_err(leaf, slot,
+                           "invalid root flags, have 0x%llx expect mask 0x%llx",
+                           btrfs_root_flags(&ri), valid_root_flags);
+               return -EUCLEAN;
+       }
+       return 0;
+}
+
 /*
  * Common point to switch the item-specific validation.
  */
@@ -856,6 +945,9 @@ static int check_leaf_item(struct extent_buffer *leaf,
        case BTRFS_INODE_ITEM_KEY:
                ret = check_inode_item(leaf, key, slot);
                break;
+       case BTRFS_ROOT_ITEM_KEY:
+               ret = check_root_item(leaf, key, slot);
+               break;
        }
        return ret;
 }