• Qu Wenruo's avatar
    btrfs: tree-checker: check extent buffer owner against owner rootid · 88c602ab
    Qu Wenruo authored
    Btrfs doesn't check whether the tree block respects the root owner.
    This means, if a tree block referred by a parent in extent tree, but has
    owner of 5, btrfs can still continue reading the tree block, as long as
    it doesn't trigger other sanity checks.
    
    Normally this is fine, but combined with the empty tree check in
    check_leaf(), if we hit an empty extent tree, but the root node has
    csum tree owner, we can let such extent buffer to sneak in.
    
    Shrink the hole by:
    
    - Do extra eb owner check at tree read time
    
    - Make sure the root owner extent buffer exactly matches the root id.
    
    Unfortunately we can't yet completely patch the hole, there are several
    call sites can't pass all info we need:
    
    - For reloc/log trees
      Their owner is key::offset, not key::objectid.
      We need the full root key to do that accurate check.
    
      For now, we just skip the ownership check for those trees.
    
    - For add_data_references() of relocation
      That call site doesn't have any parent/ownership info, as all the
      bytenrs are all from btrfs_find_all_leafs().
    
    - For direct backref items walk
      Direct backref items records the parent bytenr directly, thus unlike
      indirect backref item, we don't do a full tree search.
    
      Thus in that case, we don't have full parent owner to check.
    
    For the later two cases, they all pass 0 as @owner_root, thus we can
    skip those cases if @owner_root is 0.
    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>
    88c602ab
ctree.c 127 KB