[PATCH AUTOSEL 5.2 183/185] btrfs: tree-checker: Add ROOT_ITEM check

Sasha Levin
2019-09-22T19:21:20Z

From: Qu Wenruo <wqu@suse.com>

[ Upstream commit 259ee7754b6793af8bdd77f9ca818bc41cfe9541 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/tree-checker.c | 92 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 92 insertions(+)

diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index ccd5706199d76..d83adda6c090a 100644
--- 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;
}
--
2.20.1