310 lines
9.0 KiB
C
310 lines
9.0 KiB
C
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/*
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* Copyright (C) Qu Wenruo 2017. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program.
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*/
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/*
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* The module is used to catch unexpected/corrupted tree block data.
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* Such behavior can be caused either by a fuzzed image or bugs.
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*
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* The objective is to do leaf/node validation checks when tree block is read
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* from disk, and check *every* possible member, so other code won't
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* need to checking them again.
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*
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* Due to the potential and unwanted damage, every checker needs to be
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* carefully reviewed otherwise so it does not prevent mount of valid images.
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*/
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#include "ctree.h"
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#include "tree-checker.h"
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#include "disk-io.h"
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#include "compression.h"
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#define CORRUPT(reason, eb, root, slot) \
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btrfs_crit(root->fs_info, \
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"corrupt %s, %s: block=%llu, root=%llu, slot=%d", \
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btrfs_header_level(eb) == 0 ? "leaf" : "node", \
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reason, btrfs_header_bytenr(eb), root->objectid, slot)
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static int check_extent_data_item(struct btrfs_root *root,
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struct extent_buffer *leaf,
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struct btrfs_key *key, int slot)
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{
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struct btrfs_file_extent_item *fi;
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u32 sectorsize = root->fs_info->sectorsize;
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u32 item_size = btrfs_item_size_nr(leaf, slot);
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if (!IS_ALIGNED(key->offset, sectorsize)) {
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CORRUPT("unaligned key offset for file extent",
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leaf, root, slot);
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return -EUCLEAN;
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}
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fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
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if (btrfs_file_extent_type(leaf, fi) > BTRFS_FILE_EXTENT_TYPES) {
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CORRUPT("invalid file extent type", leaf, root, slot);
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return -EUCLEAN;
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}
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/*
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* Support for new compression/encrption must introduce incompat flag,
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* and must be caught in open_ctree().
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*/
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if (btrfs_file_extent_compression(leaf, fi) > BTRFS_COMPRESS_TYPES) {
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CORRUPT("invalid file extent compression", leaf, root, slot);
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return -EUCLEAN;
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}
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if (btrfs_file_extent_encryption(leaf, fi)) {
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CORRUPT("invalid file extent encryption", leaf, root, slot);
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return -EUCLEAN;
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}
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if (btrfs_file_extent_type(leaf, fi) == BTRFS_FILE_EXTENT_INLINE) {
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/* Inline extent must have 0 as key offset */
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if (key->offset) {
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CORRUPT("inline extent has non-zero key offset",
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leaf, root, slot);
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return -EUCLEAN;
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}
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/* Compressed inline extent has no on-disk size, skip it */
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if (btrfs_file_extent_compression(leaf, fi) !=
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BTRFS_COMPRESS_NONE)
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return 0;
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/* Uncompressed inline extent size must match item size */
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if (item_size != BTRFS_FILE_EXTENT_INLINE_DATA_START +
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btrfs_file_extent_ram_bytes(leaf, fi)) {
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CORRUPT("plaintext inline extent has invalid size",
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leaf, root, slot);
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return -EUCLEAN;
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}
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return 0;
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}
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/* Regular or preallocated extent has fixed item size */
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if (item_size != sizeof(*fi)) {
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CORRUPT(
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"regluar or preallocated extent data item size is invalid",
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leaf, root, slot);
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return -EUCLEAN;
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}
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if (!IS_ALIGNED(btrfs_file_extent_ram_bytes(leaf, fi), sectorsize) ||
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!IS_ALIGNED(btrfs_file_extent_disk_bytenr(leaf, fi), sectorsize) ||
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!IS_ALIGNED(btrfs_file_extent_disk_num_bytes(leaf, fi), sectorsize) ||
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!IS_ALIGNED(btrfs_file_extent_offset(leaf, fi), sectorsize) ||
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!IS_ALIGNED(btrfs_file_extent_num_bytes(leaf, fi), sectorsize)) {
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CORRUPT(
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"regular or preallocated extent data item has unaligned value",
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leaf, root, slot);
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return -EUCLEAN;
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}
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return 0;
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}
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static int check_csum_item(struct btrfs_root *root, struct extent_buffer *leaf,
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struct btrfs_key *key, int slot)
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{
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u32 sectorsize = root->fs_info->sectorsize;
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u32 csumsize = btrfs_super_csum_size(root->fs_info->super_copy);
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if (key->objectid != BTRFS_EXTENT_CSUM_OBJECTID) {
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CORRUPT("invalid objectid for csum item", leaf, root, slot);
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return -EUCLEAN;
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}
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if (!IS_ALIGNED(key->offset, sectorsize)) {
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CORRUPT("unaligned key offset for csum item", leaf, root, slot);
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return -EUCLEAN;
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}
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if (!IS_ALIGNED(btrfs_item_size_nr(leaf, slot), csumsize)) {
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CORRUPT("unaligned csum item size", leaf, root, slot);
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return -EUCLEAN;
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}
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return 0;
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}
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/*
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* Common point to switch the item-specific validation.
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*/
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static int check_leaf_item(struct btrfs_root *root,
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struct extent_buffer *leaf,
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struct btrfs_key *key, int slot)
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{
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int ret = 0;
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switch (key->type) {
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case BTRFS_EXTENT_DATA_KEY:
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ret = check_extent_data_item(root, leaf, key, slot);
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break;
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case BTRFS_EXTENT_CSUM_KEY:
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ret = check_csum_item(root, leaf, key, slot);
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break;
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}
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return ret;
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}
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int btrfs_check_leaf(struct btrfs_root *root, struct extent_buffer *leaf)
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{
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struct btrfs_fs_info *fs_info = root->fs_info;
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/* No valid key type is 0, so all key should be larger than this key */
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struct btrfs_key prev_key = {0, 0, 0};
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struct btrfs_key key;
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u32 nritems = btrfs_header_nritems(leaf);
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int slot;
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/*
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* Extent buffers from a relocation tree have a owner field that
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* corresponds to the subvolume tree they are based on. So just from an
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* extent buffer alone we can not find out what is the id of the
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* corresponding subvolume tree, so we can not figure out if the extent
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* buffer corresponds to the root of the relocation tree or not. So
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* skip this check for relocation trees.
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*/
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if (nritems == 0 && !btrfs_header_flag(leaf, BTRFS_HEADER_FLAG_RELOC)) {
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struct btrfs_root *check_root;
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key.objectid = btrfs_header_owner(leaf);
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key.type = BTRFS_ROOT_ITEM_KEY;
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key.offset = (u64)-1;
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check_root = btrfs_get_fs_root(fs_info, &key, false);
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/*
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* The only reason we also check NULL here is that during
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* open_ctree() some roots has not yet been set up.
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*/
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if (!IS_ERR_OR_NULL(check_root)) {
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struct extent_buffer *eb;
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eb = btrfs_root_node(check_root);
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/* if leaf is the root, then it's fine */
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if (leaf != eb) {
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CORRUPT("non-root leaf's nritems is 0",
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leaf, check_root, 0);
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free_extent_buffer(eb);
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return -EUCLEAN;
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}
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free_extent_buffer(eb);
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}
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return 0;
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}
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if (nritems == 0)
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return 0;
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/*
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* Check the following things to make sure this is a good leaf, and
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* leaf users won't need to bother with similar sanity checks:
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*
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* 1) key ordering
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* 2) item offset and size
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* No overlap, no hole, all inside the leaf.
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* 3) item content
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* If possible, do comprehensive sanity check.
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* NOTE: All checks must only rely on the item data itself.
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*/
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for (slot = 0; slot < nritems; slot++) {
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u32 item_end_expected;
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int ret;
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btrfs_item_key_to_cpu(leaf, &key, slot);
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/* Make sure the keys are in the right order */
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if (btrfs_comp_cpu_keys(&prev_key, &key) >= 0) {
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CORRUPT("bad key order", leaf, root, slot);
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return -EUCLEAN;
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}
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/*
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* Make sure the offset and ends are right, remember that the
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* item data starts at the end of the leaf and grows towards the
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* front.
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*/
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if (slot == 0)
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item_end_expected = BTRFS_LEAF_DATA_SIZE(fs_info);
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else
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item_end_expected = btrfs_item_offset_nr(leaf,
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slot - 1);
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if (btrfs_item_end_nr(leaf, slot) != item_end_expected) {
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CORRUPT("slot offset bad", leaf, root, slot);
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return -EUCLEAN;
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}
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/*
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* Check to make sure that we don't point outside of the leaf,
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* just in case all the items are consistent to each other, but
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* all point outside of the leaf.
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*/
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if (btrfs_item_end_nr(leaf, slot) >
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BTRFS_LEAF_DATA_SIZE(fs_info)) {
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CORRUPT("slot end outside of leaf", leaf, root, slot);
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return -EUCLEAN;
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}
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/* Also check if the item pointer overlaps with btrfs item. */
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if (btrfs_item_nr_offset(slot) + sizeof(struct btrfs_item) >
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btrfs_item_ptr_offset(leaf, slot)) {
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CORRUPT("slot overlap with its data", leaf, root, slot);
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return -EUCLEAN;
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}
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/* Check if the item size and content meet other criteria */
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ret = check_leaf_item(root, leaf, &key, slot);
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if (ret < 0)
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return ret;
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prev_key.objectid = key.objectid;
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prev_key.type = key.type;
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prev_key.offset = key.offset;
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}
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return 0;
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}
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int btrfs_check_node(struct btrfs_root *root, struct extent_buffer *node)
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{
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unsigned long nr = btrfs_header_nritems(node);
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struct btrfs_key key, next_key;
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int slot;
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u64 bytenr;
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int ret = 0;
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if (nr == 0 || nr > BTRFS_NODEPTRS_PER_BLOCK(root->fs_info)) {
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btrfs_crit(root->fs_info,
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"corrupt node: block %llu root %llu nritems %lu",
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node->start, root->objectid, nr);
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return -EIO;
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}
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for (slot = 0; slot < nr - 1; slot++) {
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bytenr = btrfs_node_blockptr(node, slot);
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btrfs_node_key_to_cpu(node, &key, slot);
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btrfs_node_key_to_cpu(node, &next_key, slot + 1);
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if (!bytenr) {
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CORRUPT("invalid item slot", node, root, slot);
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ret = -EIO;
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goto out;
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}
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if (btrfs_comp_cpu_keys(&key, &next_key) >= 0) {
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CORRUPT("bad key order", node, root, slot);
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ret = -EIO;
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goto out;
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}
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}
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out:
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return ret;
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}
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