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Check SPV proof inner nodes not to be valid transactions. (#4436)

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ghost43 2018-06-20 18:09:38 +02:00 • committed by GitHub
parent 7797af6ffa
commit 61a9deaa61
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1 changed files with 26 additions and 2 deletions
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28
lib/verifier.py
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@ -20,8 +20,12 @@
# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN # ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE. # SOFTWARE.
from .util import ThreadJob from .util import ThreadJob, bh2u
from .bitcoin import Hash, hash_decode, hash_encode from .bitcoin import Hash, hash_decode, hash_encode
from .transaction import Transaction
class InnerNodeOfSpvProofIsValidTx(Exception): pass
class SPV(ThreadJob): class SPV(ThreadJob):
@ -79,7 +83,12 @@ class SPV(ThreadJob):
tx_hash = params[0] tx_hash = params[0]
tx_height = merkle.get('block_height') tx_height = merkle.get('block_height')
pos = merkle.get('pos') pos = merkle.get('pos')
merkle_root = self.hash_merkle_root(merkle['merkle'], tx_hash, pos) try:
merkle_root = self.hash_merkle_root(merkle['merkle'], tx_hash, pos)
except InnerNodeOfSpvProofIsValidTx:
self.print_error("merkle verification failed for {} (inner node looks like tx)"
.format(tx_hash))
return
header = self.network.blockchain().read_header(tx_height) header = self.network.blockchain().read_header(tx_height)
# FIXME: if verification fails below, # FIXME: if verification fails below,
# we should make a fresh connection to a server to # we should make a fresh connection to a server to
@ -112,8 +121,23 @@ class SPV(ThreadJob):
for i in range(len(merkle_s)): for i in range(len(merkle_s)):
item = merkle_s[i] item = merkle_s[i]
h = Hash(hash_decode(item) + h) if ((pos >> i) & 1) else Hash(h + hash_decode(item)) h = Hash(hash_decode(item) + h) if ((pos >> i) & 1) else Hash(h + hash_decode(item))
cls._raise_if_valid_tx(bh2u(h))
return hash_encode(h) return hash_encode(h)
@classmethod
def _raise_if_valid_tx(cls, raw_tx: str):
# If an inner node of the merkle proof is also a valid tx, chances are, this is an attack.
# https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2018-June/016105.html
# https://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20180609/9f4f5b1f/attachment-0001.pdf
# https://bitcoin.stackexchange.com/questions/76121/how-is-the-leaf-node-weakness-in-merkle-trees-exploitable/76122#76122
tx = Transaction(raw_tx)
try:
tx.deserialize()
except:
pass
else:
raise InnerNodeOfSpvProofIsValidTx()
def undo_verifications(self): def undo_verifications(self):
height = self.blockchain.get_checkpoint() height = self.blockchain.get_checkpoint()
tx_hashes = self.wallet.undo_verifications(self.blockchain, height) tx_hashes = self.wallet.undo_verifications(self.blockchain, height)