Commit 259ee775 authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

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: default avatarJungyeon Yoon <jungyeon.yoon@gmail.com>
Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 2a28468e

fs/btrfs/tree-checker.c

+92 −0
Original line number Diff line number Diff line
@@ -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;

}

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