On 2018年07月04日 13:45, Gu, Jinxiang wrote: > > >> -----Original Message----- >> From: linux-btrfs-owner@xxxxxxxxxxxxxxx [mailto:linux-btrfs-owner@xxxxxxxxxxxxxxx] On Behalf Of Qu Wenruo >> Sent: Tuesday, July 03, 2018 5:10 PM >> To: linux-btrfs@xxxxxxxxxxxxxxx >> Subject: [PATCH 4/5] btrfs: Check each block group has corresponding chunk at mount time >> >> A crafted btrfs with incorrect chunk<->block group mapping, it could leads >> to a lot of unexpected behavior. >> >> Although the crafted image can be catched by block group item checker >> added in "[PATCH] btrfs: tree-checker: Verify block_group_item", if one >> crafted a valid enough block group item which can pass above check but >> still mismatch with existing chunk, it could cause a lot of undefined >> behavior. >> >> This patch will add extra block group -> chunk mapping check, to ensure >> we have a completely matching (start, len, flags) chunk for each block >> group at mount time. >> >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=199837 >> Reported-by: Xu Wen <wen.xu@xxxxxxxxxx> >> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx> >> --- >> fs/btrfs/extent-tree.c | 55 ++++++++++++++++++++++++++++++++++++++++-- >> 1 file changed, 53 insertions(+), 2 deletions(-) >> >> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c >> index 3d9fe58c0080..82b446f014b9 100644 >> --- a/fs/btrfs/extent-tree.c >> +++ b/fs/btrfs/extent-tree.c >> @@ -10003,6 +10003,41 @@ btrfs_create_block_group_cache(struct btrfs_fs_info *fs_info, >> return cache; >> } >> >> +static int check_exist_chunk(struct btrfs_fs_info *fs_info, u64 start, u64 len, >> + u64 flags) >> +{ >> + struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree; >> + struct extent_map *em; >> + int ret; >> + >> + read_lock(&map_tree->map_tree.lock); >> + em = lookup_extent_mapping(&map_tree->map_tree, start, len); >> + read_unlock(&map_tree->map_tree.lock); >> + >> + if (!em) { >> + btrfs_err_rl(fs_info, >> + "block group start=%llu len=%llu doesn't have corresponding chunk", >> + start, len); >> + ret = -ENOENT; >> + goto out; >> + } > > This check has been done in find_first_block_group which has been called before > check_exist_chunk be called. Oh, yes, find_first_block_group() indeed does this check, so there is no need for check_exsist_chunk(). > >> + if (em->start != start || em->len != len || >> + (em->map_lookup->type & BTRFS_BLOCK_GROUP_TYPE_MASK) != >> + (flags & BTRFS_BLOCK_GROUP_TYPE_MASK)) { >> + btrfs_err_rl(fs_info, >> +"block group start=%llu len=%llu flags=0x%llx doesn't match with chunk start=%llu len=%llu flags=0x%llx", >> + start, len , flags & BTRFS_BLOCK_GROUP_TYPE_MASK, >> + em->start, em->len, em->map_lookup->type & >> + BTRFS_BLOCK_GROUP_TYPE_MASK); >> + ret = -EUCLEAN; >> + goto out; >> + } > Should this check also be added to find_first_block_group? Yep. Thanks, Qu > >> + ret = 0; >> +out: >> + free_extent_map(em); >> + return ret; >> +} >> + >> int btrfs_read_block_groups(struct btrfs_fs_info *info) >> { >> struct btrfs_path *path; >> @@ -10036,6 +10071,9 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info) >> need_clear = 1; >> >> while (1) { >> + struct btrfs_block_group_item bg; >> + int slot; >> + >> ret = find_first_block_group(info, path, &key); >> if (ret > 0) >> break; >> @@ -10043,7 +10081,20 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info) >> goto error; >> >> leaf = path->nodes[0]; >> - btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); >> + slot = path->slots[0]; >> + btrfs_item_key_to_cpu(leaf, &found_key, slot); >> + >> + read_extent_buffer(leaf, &bg, btrfs_item_ptr_offset(leaf, slot), >> + sizeof(bg)); >> + /* >> + * Chunk and block group must have 1:1 mapping. >> + * So there must be a chunk for this block group. >> + */ >> + ret = check_exist_chunk(info, found_key.objectid, >> + found_key.offset, >> + btrfs_block_group_flags(&bg)); >> + if (ret < 0) >> + goto error; >> >> cache = btrfs_create_block_group_cache(info, found_key.objectid, >> found_key.offset); >> @@ -10068,7 +10119,7 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info) >> } >> >> read_extent_buffer(leaf, &cache->item, >> - btrfs_item_ptr_offset(leaf, path->slots[0]), >> + btrfs_item_ptr_offset(leaf, slot), >> sizeof(cache->item)); >> cache->flags = btrfs_block_group_flags(&cache->item); >> if (!mixed && >> -- >> 2.18.0 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > > > > N嫥叉靣笡y氊b瞂千v豝�)藓{.n�+壏{眓谶�)韰骅w* jg� 秹殠娸/侁鋤罐枈�2娹櫒璀�&�)摺玜囤 瓽珴閔�鎗:+v墾妛鑶佶 >
Attachment:
signature.asc
Description: OpenPGP digital signature
