Commit f82d1c7c authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: tree-checker: Add EXTENT_ITEM and METADATA_ITEM check 



This patch introduces the ability to check extent items.

This check involves:
- key->objectid check
  Basic alignment check.

- key->type check
  Against btrfs_extent_item::type and SKINNY_METADATA feature.

- key->offset alignment check for EXTENT_ITEM

- key->offset check for METADATA_ITEM

- item size check
  Both against minimal size and stepping check.

- btrfs_extent_item check
  Checks its flags and generation.

- btrfs_extent_inline_ref checks
  Against 4 types inline ref.
  Checks bytenr alignment and tree level.

- btrfs_extent_item::refs check
  Check against total refs found in inline refs.

This check would be the most complex single item check due to its nature
of inlined items.

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 f1136989

fs/btrfs/tree-checker.c

+248 −0
Original line number Diff line number Diff line
@@ -910,6 +910,250 @@ static int check_root_item(struct extent_buffer *leaf, struct btrfs_key *key, 
	return 0;

}



__printf(3,4)

__cold

static void extent_err(const struct extent_buffer *eb, int slot,

		       const char *fmt, ...)

{

	struct btrfs_key key;

	struct va_format vaf;

	va_list args;

	u64 bytenr;

	u64 len;



	btrfs_item_key_to_cpu(eb, &key, slot);

	bytenr = key.objectid;

	if (key.type == BTRFS_METADATA_ITEM_KEY)

		len = eb->fs_info->nodesize;

	else

		len = key.offset;

	va_start(args, fmt);



	vaf.fmt = fmt;

	vaf.va = &args;



	btrfs_crit(eb->fs_info,

	"corrupt %s: block=%llu slot=%d extent bytenr=%llu len=%llu %pV",

		btrfs_header_level(eb) == 0 ? "leaf" : "node",

		eb->start, slot, bytenr, len, &vaf);

	va_end(args);

}



static int check_extent_item(struct extent_buffer *leaf,

			     struct btrfs_key *key, int slot)

{

	struct btrfs_fs_info *fs_info = leaf->fs_info;

	struct btrfs_extent_item *ei;

	bool is_tree_block = false;

	unsigned long ptr;	/* Current pointer inside inline refs */

	unsigned long end;	/* Extent item end */

	const u32 item_size = btrfs_item_size_nr(leaf, slot);

	u64 flags;

	u64 generation;

	u64 total_refs;		/* Total refs in btrfs_extent_item */

	u64 inline_refs = 0;	/* found total inline refs */



	if (key->type == BTRFS_METADATA_ITEM_KEY &&

	    !btrfs_fs_incompat(fs_info, SKINNY_METADATA)) {

		generic_err(leaf, slot,

"invalid key type, METADATA_ITEM type invalid when SKINNY_METADATA feature disabled");

		return -EUCLEAN;

	}

	/* key->objectid is the bytenr for both key types */

	if (!IS_ALIGNED(key->objectid, fs_info->sectorsize)) {

		generic_err(leaf, slot,

		"invalid key objectid, have %llu expect to be aligned to %u",

			   key->objectid, fs_info->sectorsize);

		return -EUCLEAN;

	}



	/* key->offset is tree level for METADATA_ITEM_KEY */

	if (key->type == BTRFS_METADATA_ITEM_KEY &&

	    key->offset >= BTRFS_MAX_LEVEL) {

		extent_err(leaf, slot,

			   "invalid tree level, have %llu expect [0, %u]",

			   key->offset, BTRFS_MAX_LEVEL - 1);

		return -EUCLEAN;

	}



	/*

	 * EXTENT/METADATA_ITEM consists of:

	 * 1) One btrfs_extent_item

	 *    Records the total refs, type and generation of the extent.

	 *

	 * 2) One btrfs_tree_block_info (for EXTENT_ITEM and tree backref only)

	 *    Records the first key and level of the tree block.

	 *

	 * 2) Zero or more btrfs_extent_inline_ref(s)

	 *    Each inline ref has one btrfs_extent_inline_ref shows:

	 *    2.1) The ref type, one of the 4

	 *         TREE_BLOCK_REF	Tree block only

	 *         SHARED_BLOCK_REF	Tree block only

	 *         EXTENT_DATA_REF	Data only

	 *         SHARED_DATA_REF	Data only

	 *    2.2) Ref type specific data

	 *         Either using btrfs_extent_inline_ref::offset, or specific

	 *         data structure.

	 */

	if (item_size < sizeof(*ei)) {

		extent_err(leaf, slot,

			   "invalid item size, have %u expect [%zu, %u)",

			   item_size, sizeof(*ei),

			   BTRFS_LEAF_DATA_SIZE(fs_info));

		return -EUCLEAN;

	}

	end = item_size + btrfs_item_ptr_offset(leaf, slot);



	/* Checks against extent_item */

	ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);

	flags = btrfs_extent_flags(leaf, ei);

	total_refs = btrfs_extent_refs(leaf, ei);

	generation = btrfs_extent_generation(leaf, ei);

	if (generation > btrfs_super_generation(fs_info->super_copy) + 1) {

		extent_err(leaf, slot,

			   "invalid generation, have %llu expect (0, %llu]",

			   generation,

			   btrfs_super_generation(fs_info->super_copy) + 1);

		return -EUCLEAN;

	}

	if (!is_power_of_2(flags & (BTRFS_EXTENT_FLAG_DATA |

				    BTRFS_EXTENT_FLAG_TREE_BLOCK))) {

		extent_err(leaf, slot,

		"invalid extent flag, have 0x%llx expect 1 bit set in 0x%llx",

			flags, BTRFS_EXTENT_FLAG_DATA |

			BTRFS_EXTENT_FLAG_TREE_BLOCK);

		return -EUCLEAN;

	}

	is_tree_block = !!(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK);

	if (is_tree_block) {

		if (key->type == BTRFS_EXTENT_ITEM_KEY &&

		    key->offset != fs_info->nodesize) {

			extent_err(leaf, slot,

				   "invalid extent length, have %llu expect %u",

				   key->offset, fs_info->nodesize);

			return -EUCLEAN;

		}

	} else {

		if (key->type != BTRFS_EXTENT_ITEM_KEY) {

			extent_err(leaf, slot,

			"invalid key type, have %u expect %u for data backref",

				   key->type, BTRFS_EXTENT_ITEM_KEY);

			return -EUCLEAN;

		}

		if (!IS_ALIGNED(key->offset, fs_info->sectorsize)) {

			extent_err(leaf, slot,

			"invalid extent length, have %llu expect aligned to %u",

				   key->offset, fs_info->sectorsize);

			return -EUCLEAN;

		}

	}

	ptr = (unsigned long)(struct btrfs_extent_item *)(ei + 1);



	/* Check the special case of btrfs_tree_block_info */

	if (is_tree_block && key->type != BTRFS_METADATA_ITEM_KEY) {

		struct btrfs_tree_block_info *info;



		info = (struct btrfs_tree_block_info *)ptr;

		if (btrfs_tree_block_level(leaf, info) >= BTRFS_MAX_LEVEL) {

			extent_err(leaf, slot,

			"invalid tree block info level, have %u expect [0, %u]",

				   btrfs_tree_block_level(leaf, info),

				   BTRFS_MAX_LEVEL - 1);

			return -EUCLEAN;

		}

		ptr = (unsigned long)(struct btrfs_tree_block_info *)(info + 1);

	}



	/* Check inline refs */

	while (ptr < end) {

		struct btrfs_extent_inline_ref *iref;

		struct btrfs_extent_data_ref *dref;

		struct btrfs_shared_data_ref *sref;

		u64 dref_offset;

		u64 inline_offset;

		u8 inline_type;



		if (ptr + sizeof(*iref) > end) {

			extent_err(leaf, slot,

"inline ref item overflows extent item, ptr %lu iref size %zu end %lu",

				   ptr, sizeof(*iref), end);

			return -EUCLEAN;

		}

		iref = (struct btrfs_extent_inline_ref *)ptr;

		inline_type = btrfs_extent_inline_ref_type(leaf, iref);

		inline_offset = btrfs_extent_inline_ref_offset(leaf, iref);

		if (ptr + btrfs_extent_inline_ref_size(inline_type) > end) {

			extent_err(leaf, slot,

"inline ref item overflows extent item, ptr %lu iref size %u end %lu",

				   ptr, inline_type, end);

			return -EUCLEAN;

		}



		switch (inline_type) {

		/* inline_offset is subvolid of the owner, no need to check */

		case BTRFS_TREE_BLOCK_REF_KEY:

			inline_refs++;

			break;

		/* Contains parent bytenr */

		case BTRFS_SHARED_BLOCK_REF_KEY:

			if (!IS_ALIGNED(inline_offset, fs_info->sectorsize)) {

				extent_err(leaf, slot,

		"invalid tree parent bytenr, have %llu expect aligned to %u",

					   inline_offset, fs_info->sectorsize);

				return -EUCLEAN;

			}

			inline_refs++;

			break;

		/*

		 * Contains owner subvolid, owner key objectid, adjusted offset.

		 * The only obvious corruption can happen in that offset.

		 */

		case BTRFS_EXTENT_DATA_REF_KEY:

			dref = (struct btrfs_extent_data_ref *)(&iref->offset);

			dref_offset = btrfs_extent_data_ref_offset(leaf, dref);

			if (!IS_ALIGNED(dref_offset, fs_info->sectorsize)) {

				extent_err(leaf, slot,

		"invalid data ref offset, have %llu expect aligned to %u",

					   dref_offset, fs_info->sectorsize);

				return -EUCLEAN;

			}

			inline_refs += btrfs_extent_data_ref_count(leaf, dref);

			break;

		/* Contains parent bytenr and ref count */

		case BTRFS_SHARED_DATA_REF_KEY:

			sref = (struct btrfs_shared_data_ref *)(iref + 1);

			if (!IS_ALIGNED(inline_offset, fs_info->sectorsize)) {

				extent_err(leaf, slot,

		"invalid data parent bytenr, have %llu expect aligned to %u",

					   inline_offset, fs_info->sectorsize);

				return -EUCLEAN;

			}

			inline_refs += btrfs_shared_data_ref_count(leaf, sref);

			break;

		default:

			extent_err(leaf, slot, "unknown inline ref type: %u",

				   inline_type);

			return -EUCLEAN;

		}

		ptr += btrfs_extent_inline_ref_size(inline_type);

	}

	/* No padding is allowed */

	if (ptr != end) {

		extent_err(leaf, slot,

			   "invalid extent item size, padding bytes found");

		return -EUCLEAN;

	}



	/* Finally, check the inline refs against total refs */

	if (inline_refs > total_refs) {

		extent_err(leaf, slot,

			"invalid extent refs, have %llu expect >= inline %llu",

			   total_refs, inline_refs);

		return -EUCLEAN;

	}

	return 0;

}



/*

 * Common point to switch the item-specific validation.

 */
@@ -948,6 +1192,10 @@ static int check_leaf_item(struct extent_buffer *leaf, 
	case BTRFS_ROOT_ITEM_KEY:

		ret = check_root_item(leaf, key, slot);

		break;

	case BTRFS_EXTENT_ITEM_KEY:

	case BTRFS_METADATA_ITEM_KEY:

		ret = check_extent_item(leaf, key, slot);

		break;

	}

	return ret;

}

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