btrfs: Move leaf and node validation checker to tree-checker.c
commit 557ea5dd003d371536f6b4e8f7c8209a2b6fd4e3 upstream.
It's no doubt the comprehensive tree block checker will become larger,
so moving them into their own files is quite reasonable.
Signed-off-by: Qu Wenruo <quwenruo.btrfs@gmx.com>
[ wording adjustments ]
Signed-off-by: David Sterba <dsterba@suse.com>
[bwh: Backported to 4.9: The moved code is slightly different]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
new file mode 100644
index 0000000..dfba9f6
--- /dev/null
+++ b/fs/btrfs/tree-checker.c
@@ -0,0 +1,309 @@
+/*
+ * Copyright (C) Qu Wenruo 2017. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program.
+ */
+
+/*
+ * The module is used to catch unexpected/corrupted tree block data.
+ * Such behavior can be caused either by a fuzzed image or bugs.
+ *
+ * The objective is to do leaf/node validation checks when tree block is read
+ * from disk, and check *every* possible member, so other code won't
+ * need to checking them again.
+ *
+ * Due to the potential and unwanted damage, every checker needs to be
+ * carefully reviewed otherwise so it does not prevent mount of valid images.
+ */
+
+#include "ctree.h"
+#include "tree-checker.h"
+#include "disk-io.h"
+#include "compression.h"
+
+#define CORRUPT(reason, eb, root, slot) \
+ btrfs_crit(root->fs_info, \
+ "corrupt %s, %s: block=%llu, root=%llu, slot=%d", \
+ btrfs_header_level(eb) == 0 ? "leaf" : "node", \
+ reason, btrfs_header_bytenr(eb), root->objectid, slot)
+
+static int check_extent_data_item(struct btrfs_root *root,
+ struct extent_buffer *leaf,
+ struct btrfs_key *key, int slot)
+{
+ struct btrfs_file_extent_item *fi;
+ u32 sectorsize = root->sectorsize;
+ u32 item_size = btrfs_item_size_nr(leaf, slot);
+
+ if (!IS_ALIGNED(key->offset, sectorsize)) {
+ CORRUPT("unaligned key offset for file extent",
+ leaf, root, slot);
+ return -EUCLEAN;
+ }
+
+ fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
+
+ if (btrfs_file_extent_type(leaf, fi) > BTRFS_FILE_EXTENT_TYPES) {
+ CORRUPT("invalid file extent type", leaf, root, slot);
+ return -EUCLEAN;
+ }
+
+ /*
+ * Support for new compression/encrption must introduce incompat flag,
+ * and must be caught in open_ctree().
+ */
+ if (btrfs_file_extent_compression(leaf, fi) > BTRFS_COMPRESS_TYPES) {
+ CORRUPT("invalid file extent compression", leaf, root, slot);
+ return -EUCLEAN;
+ }
+ if (btrfs_file_extent_encryption(leaf, fi)) {
+ CORRUPT("invalid file extent encryption", leaf, root, slot);
+ return -EUCLEAN;
+ }
+ if (btrfs_file_extent_type(leaf, fi) == BTRFS_FILE_EXTENT_INLINE) {
+ /* Inline extent must have 0 as key offset */
+ if (key->offset) {
+ CORRUPT("inline extent has non-zero key offset",
+ leaf, root, slot);
+ return -EUCLEAN;
+ }
+
+ /* Compressed inline extent has no on-disk size, skip it */
+ if (btrfs_file_extent_compression(leaf, fi) !=
+ BTRFS_COMPRESS_NONE)
+ return 0;
+
+ /* Uncompressed inline extent size must match item size */
+ if (item_size != BTRFS_FILE_EXTENT_INLINE_DATA_START +
+ btrfs_file_extent_ram_bytes(leaf, fi)) {
+ CORRUPT("plaintext inline extent has invalid size",
+ leaf, root, slot);
+ return -EUCLEAN;
+ }
+ return 0;
+ }
+
+ /* Regular or preallocated extent has fixed item size */
+ if (item_size != sizeof(*fi)) {
+ CORRUPT(
+ "regluar or preallocated extent data item size is invalid",
+ leaf, root, slot);
+ return -EUCLEAN;
+ }
+ if (!IS_ALIGNED(btrfs_file_extent_ram_bytes(leaf, fi), sectorsize) ||
+ !IS_ALIGNED(btrfs_file_extent_disk_bytenr(leaf, fi), sectorsize) ||
+ !IS_ALIGNED(btrfs_file_extent_disk_num_bytes(leaf, fi), sectorsize) ||
+ !IS_ALIGNED(btrfs_file_extent_offset(leaf, fi), sectorsize) ||
+ !IS_ALIGNED(btrfs_file_extent_num_bytes(leaf, fi), sectorsize)) {
+ CORRUPT(
+ "regular or preallocated extent data item has unaligned value",
+ leaf, root, slot);
+ return -EUCLEAN;
+ }
+
+ return 0;
+}
+
+static int check_csum_item(struct btrfs_root *root, struct extent_buffer *leaf,
+ struct btrfs_key *key, int slot)
+{
+ u32 sectorsize = root->sectorsize;
+ u32 csumsize = btrfs_super_csum_size(root->fs_info->super_copy);
+
+ if (key->objectid != BTRFS_EXTENT_CSUM_OBJECTID) {
+ CORRUPT("invalid objectid for csum item", leaf, root, slot);
+ return -EUCLEAN;
+ }
+ if (!IS_ALIGNED(key->offset, sectorsize)) {
+ CORRUPT("unaligned key offset for csum item", leaf, root, slot);
+ return -EUCLEAN;
+ }
+ if (!IS_ALIGNED(btrfs_item_size_nr(leaf, slot), csumsize)) {
+ CORRUPT("unaligned csum item size", leaf, root, slot);
+ return -EUCLEAN;
+ }
+ return 0;
+}
+
+/*
+ * Common point to switch the item-specific validation.
+ */
+static int check_leaf_item(struct btrfs_root *root,
+ struct extent_buffer *leaf,
+ struct btrfs_key *key, int slot)
+{
+ int ret = 0;
+
+ switch (key->type) {
+ case BTRFS_EXTENT_DATA_KEY:
+ ret = check_extent_data_item(root, leaf, key, slot);
+ break;
+ case BTRFS_EXTENT_CSUM_KEY:
+ ret = check_csum_item(root, leaf, key, slot);
+ break;
+ }
+ return ret;
+}
+
+int btrfs_check_leaf(struct btrfs_root *root, struct extent_buffer *leaf)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ /* No valid key type is 0, so all key should be larger than this key */
+ struct btrfs_key prev_key = {0, 0, 0};
+ struct btrfs_key key;
+ u32 nritems = btrfs_header_nritems(leaf);
+ int slot;
+
+ /*
+ * Extent buffers from a relocation tree have a owner field that
+ * corresponds to the subvolume tree they are based on. So just from an
+ * extent buffer alone we can not find out what is the id of the
+ * corresponding subvolume tree, so we can not figure out if the extent
+ * buffer corresponds to the root of the relocation tree or not. So
+ * skip this check for relocation trees.
+ */
+ if (nritems == 0 && !btrfs_header_flag(leaf, BTRFS_HEADER_FLAG_RELOC)) {
+ struct btrfs_root *check_root;
+
+ key.objectid = btrfs_header_owner(leaf);
+ key.type = BTRFS_ROOT_ITEM_KEY;
+ key.offset = (u64)-1;
+
+ check_root = btrfs_get_fs_root(fs_info, &key, false);
+ /*
+ * The only reason we also check NULL here is that during
+ * open_ctree() some roots has not yet been set up.
+ */
+ if (!IS_ERR_OR_NULL(check_root)) {
+ struct extent_buffer *eb;
+
+ eb = btrfs_root_node(check_root);
+ /* if leaf is the root, then it's fine */
+ if (leaf != eb) {
+ CORRUPT("non-root leaf's nritems is 0",
+ leaf, check_root, 0);
+ free_extent_buffer(eb);
+ return -EUCLEAN;
+ }
+ free_extent_buffer(eb);
+ }
+ return 0;
+ }
+
+ if (nritems == 0)
+ return 0;
+
+ /*
+ * Check the following things to make sure this is a good leaf, and
+ * leaf users won't need to bother with similar sanity checks:
+ *
+ * 1) key ordering
+ * 2) item offset and size
+ * No overlap, no hole, all inside the leaf.
+ * 3) item content
+ * If possible, do comprehensive sanity check.
+ * NOTE: All checks must only rely on the item data itself.
+ */
+ for (slot = 0; slot < nritems; slot++) {
+ u32 item_end_expected;
+ int ret;
+
+ btrfs_item_key_to_cpu(leaf, &key, slot);
+
+ /* Make sure the keys are in the right order */
+ if (btrfs_comp_cpu_keys(&prev_key, &key) >= 0) {
+ CORRUPT("bad key order", leaf, root, slot);
+ return -EUCLEAN;
+ }
+
+ /*
+ * Make sure the offset and ends are right, remember that the
+ * item data starts at the end of the leaf and grows towards the
+ * front.
+ */
+ if (slot == 0)
+ item_end_expected = BTRFS_LEAF_DATA_SIZE(root);
+ else
+ item_end_expected = btrfs_item_offset_nr(leaf,
+ slot - 1);
+ if (btrfs_item_end_nr(leaf, slot) != item_end_expected) {
+ CORRUPT("slot offset bad", leaf, root, slot);
+ return -EUCLEAN;
+ }
+
+ /*
+ * Check to make sure that we don't point outside of the leaf,
+ * just in case all the items are consistent to each other, but
+ * all point outside of the leaf.
+ */
+ if (btrfs_item_end_nr(leaf, slot) >
+ BTRFS_LEAF_DATA_SIZE(root)) {
+ CORRUPT("slot end outside of leaf", leaf, root, slot);
+ return -EUCLEAN;
+ }
+
+ /* Also check if the item pointer overlaps with btrfs item. */
+ if (btrfs_item_nr_offset(slot) + sizeof(struct btrfs_item) >
+ btrfs_item_ptr_offset(leaf, slot)) {
+ CORRUPT("slot overlap with its data", leaf, root, slot);
+ return -EUCLEAN;
+ }
+
+ /* Check if the item size and content meet other criteria */
+ ret = check_leaf_item(root, leaf, &key, slot);
+ if (ret < 0)
+ return ret;
+
+ prev_key.objectid = key.objectid;
+ prev_key.type = key.type;
+ prev_key.offset = key.offset;
+ }
+
+ return 0;
+}
+
+int btrfs_check_node(struct btrfs_root *root, struct extent_buffer *node)
+{
+ unsigned long nr = btrfs_header_nritems(node);
+ struct btrfs_key key, next_key;
+ int slot;
+ u64 bytenr;
+ int ret = 0;
+
+ if (nr == 0 || nr > BTRFS_NODEPTRS_PER_BLOCK(root)) {
+ btrfs_crit(root->fs_info,
+ "corrupt node: block %llu root %llu nritems %lu",
+ node->start, root->objectid, nr);
+ return -EIO;
+ }
+
+ for (slot = 0; slot < nr - 1; slot++) {
+ bytenr = btrfs_node_blockptr(node, slot);
+ btrfs_node_key_to_cpu(node, &key, slot);
+ btrfs_node_key_to_cpu(node, &next_key, slot + 1);
+
+ if (!bytenr) {
+ CORRUPT("invalid item slot", node, root, slot);
+ ret = -EIO;
+ goto out;
+ }
+
+ if (btrfs_comp_cpu_keys(&key, &next_key) >= 0) {
+ CORRUPT("bad key order", node, root, slot);
+ ret = -EIO;
+ goto out;
+ }
+ }
+out:
+ return ret;
+}