diff options
| -rw-r--r-- | doc/release-notes-26265.md | 6 | ||||
| -rw-r--r-- | src/policy/policy.h | 4 | ||||
| -rw-r--r-- | src/validation.cpp | 5 | ||||
| -rw-r--r-- | test/functional/data/invalid_txs.py | 9 | ||||
| -rwxr-xr-x | test/functional/mempool_accept.py | 37 | ||||
| -rwxr-xr-x | test/functional/test_framework/script_util.py | 21 |
6 files changed, 63 insertions, 19 deletions
diff --git a/doc/release-notes-26265.md b/doc/release-notes-26265.md new file mode 100644 index 0000000000..ca2313d956 --- /dev/null +++ b/doc/release-notes-26265.md @@ -0,0 +1,6 @@ +P2P and network changes +--------- + +- Transactions of non-witness size 65 and above are now allowed by mempool + and relay policy. This is to better reflect the actual afforded protections + against CVE-2017-12842 and open up additional use-cases of smaller transaction sizes. (#26265) diff --git a/src/policy/policy.h b/src/policy/policy.h index 29764ea2d9..8a26e70ef4 100644 --- a/src/policy/policy.h +++ b/src/policy/policy.h @@ -25,8 +25,8 @@ static constexpr unsigned int DEFAULT_BLOCK_MAX_WEIGHT{MAX_BLOCK_WEIGHT - 4000}; static constexpr unsigned int DEFAULT_BLOCK_MIN_TX_FEE{1000}; /** The maximum weight for transactions we're willing to relay/mine */ static constexpr unsigned int MAX_STANDARD_TX_WEIGHT{400000}; -/** The minimum non-witness size for transactions we're willing to relay/mine (1 segwit input + 1 P2WPKH output = 82 bytes) */ -static constexpr unsigned int MIN_STANDARD_TX_NONWITNESS_SIZE{82}; +/** The minimum non-witness size for transactions we're willing to relay/mine: one larger than 64 */ +static constexpr unsigned int MIN_STANDARD_TX_NONWITNESS_SIZE{65}; /** Maximum number of signature check operations in an IsStandard() P2SH script */ static constexpr unsigned int MAX_P2SH_SIGOPS{15}; /** The maximum number of sigops we're willing to relay/mine in a single tx */ diff --git a/src/validation.cpp b/src/validation.cpp index 76bea97341..15d72c903a 100644 --- a/src/validation.cpp +++ b/src/validation.cpp @@ -690,10 +690,7 @@ bool MemPoolAccept::PreChecks(ATMPArgs& args, Workspace& ws) return state.Invalid(TxValidationResult::TX_NOT_STANDARD, reason); } - // Do not work on transactions that are too small. - // A transaction with 1 segwit input and 1 P2WPHK output has non-witness size of 82 bytes. - // Transactions smaller than this are not relayed to mitigate CVE-2017-12842 by not relaying - // 64-byte transactions. + // Transactions smaller than 65 non-witness bytes are not relayed to mitigate CVE-2017-12842. if (::GetSerializeSize(tx, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) < MIN_STANDARD_TX_NONWITNESS_SIZE) return state.Invalid(TxValidationResult::TX_NOT_STANDARD, "tx-size-small"); diff --git a/test/functional/data/invalid_txs.py b/test/functional/data/invalid_txs.py index 3747b2a98d..7892410826 100644 --- a/test/functional/data/invalid_txs.py +++ b/test/functional/data/invalid_txs.py @@ -46,18 +46,19 @@ from test_framework.script import ( OP_MOD, OP_MUL, OP_OR, + OP_RETURN, OP_RIGHT, OP_RSHIFT, OP_SUBSTR, - OP_TRUE, OP_XOR, ) from test_framework.script_util import ( + MIN_PADDING, + MIN_STANDARD_TX_NONWITNESS_SIZE, script_to_p2sh_script, ) basic_p2sh = script_to_p2sh_script(CScript([OP_0])) - class BadTxTemplate: """Allows simple construction of a certain kind of invalid tx. Base class to be subclassed.""" __metaclass__ = abc.ABCMeta @@ -122,7 +123,9 @@ class SizeTooSmall(BadTxTemplate): def get_tx(self): tx = CTransaction() tx.vin.append(self.valid_txin) - tx.vout.append(CTxOut(0, CScript([OP_TRUE]))) + tx.vout.append(CTxOut(0, CScript([OP_RETURN] + ([OP_0] * (MIN_PADDING - 2))))) + assert len(tx.serialize_without_witness()) == 64 + assert MIN_STANDARD_TX_NONWITNESS_SIZE - 1 == 64 tx.calc_sha256() return tx diff --git a/test/functional/mempool_accept.py b/test/functional/mempool_accept.py index 02ec18140c..7ec3fbe7cf 100755 --- a/test/functional/mempool_accept.py +++ b/test/functional/mempool_accept.py @@ -14,7 +14,9 @@ from test_framework.messages import ( MAX_BIP125_RBF_SEQUENCE, COIN, COutPoint, + CTransaction, CTxIn, + CTxInWitness, CTxOut, MAX_BLOCK_WEIGHT, MAX_MONEY, @@ -26,13 +28,19 @@ from test_framework.script import ( OP_0, OP_HASH160, OP_RETURN, + OP_TRUE, ) from test_framework.script_util import ( + DUMMY_MIN_OP_RETURN_SCRIPT, keys_to_multisig_script, + MIN_PADDING, + MIN_STANDARD_TX_NONWITNESS_SIZE, script_to_p2sh_script, + script_to_p2wsh_script, ) from test_framework.util import ( assert_equal, + assert_greater_than, assert_raises_rpc_error, ) from test_framework.wallet import MiniWallet @@ -333,6 +341,35 @@ class MempoolAcceptanceTest(BitcoinTestFramework): maxfeerate=0, ) + # Prep for tiny-tx tests with wsh(OP_TRUE) output + seed_tx = self.wallet.send_to(from_node=node, scriptPubKey=script_to_p2wsh_script(CScript([OP_TRUE])), amount=COIN) + self.generate(node, 1) + + self.log.info('A tiny transaction(in non-witness bytes) that is disallowed') + tx = CTransaction() + tx.vin.append(CTxIn(COutPoint(int(seed_tx[0], 16), seed_tx[1]), b"", SEQUENCE_FINAL)) + tx.wit.vtxinwit = [CTxInWitness()] + tx.wit.vtxinwit[0].scriptWitness.stack = [CScript([OP_TRUE])] + tx.vout.append(CTxOut(0, CScript([OP_RETURN] + ([OP_0] * (MIN_PADDING - 2))))) + # Note it's only non-witness size that matters! + assert_equal(len(tx.serialize_without_witness()), 64) + assert_equal(MIN_STANDARD_TX_NONWITNESS_SIZE - 1, 64) + assert_greater_than(len(tx.serialize()), 64) + + self.check_mempool_result( + result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': 'tx-size-small'}], + rawtxs=[tx.serialize().hex()], + maxfeerate=0, + ) + + self.log.info('Minimally-small transaction(in non-witness bytes) that is allowed') + tx.vout[0] = CTxOut(COIN - 1000, DUMMY_MIN_OP_RETURN_SCRIPT) + assert_equal(len(tx.serialize_without_witness()), MIN_STANDARD_TX_NONWITNESS_SIZE) + self.check_mempool_result( + result_expected=[{'txid': tx.rehash(), 'allowed': True, 'vsize': tx.get_vsize(), 'fees': { 'base': Decimal('0.00001000')}}], + rawtxs=[tx.serialize().hex()], + maxfeerate=0, + ) if __name__ == '__main__': MempoolAcceptanceTest().main() diff --git a/test/functional/test_framework/script_util.py b/test/functional/test_framework/script_util.py index b114002145..39dcb418b7 100755 --- a/test/functional/test_framework/script_util.py +++ b/test/functional/test_framework/script_util.py @@ -13,12 +13,13 @@ from test_framework.script import ( OP_EQUAL, OP_EQUALVERIFY, OP_HASH160, + OP_RETURN, hash160, sha256, ) # To prevent a "tx-size-small" policy rule error, a transaction has to have a -# non-witness size of at least 82 bytes (MIN_STANDARD_TX_NONWITNESS_SIZE in +# non-witness size of at least 65 bytes (MIN_STANDARD_TX_NONWITNESS_SIZE in # src/policy/policy.h). Considering a Tx with the smallest possible single # input (blank, empty scriptSig), and with an output omitting the scriptPubKey, # we get to a minimum size of 60 bytes: @@ -28,15 +29,15 @@ from test_framework.script import ( # Output: 8 [Amount] + 1 [scriptPubKeyLen] = 9 bytes # # Hence, the scriptPubKey of the single output has to have a size of at -# least 22 bytes, which corresponds to the size of a P2WPKH scriptPubKey. -# The following script constant consists of a single push of 21 bytes of 'a': -# <PUSH_21> <21-bytes of 'a'> -# resulting in a 22-byte size. It should be used whenever (small) fake -# scriptPubKeys are needed, to guarantee that the minimum transaction size is -# met. -DUMMY_P2WPKH_SCRIPT = CScript([b'a' * 21]) -DUMMY_2_P2WPKH_SCRIPT = CScript([b'b' * 21]) - +# least 5 bytes. +MIN_STANDARD_TX_NONWITNESS_SIZE = 65 +MIN_PADDING = MIN_STANDARD_TX_NONWITNESS_SIZE - 10 - 41 - 9 +assert MIN_PADDING == 5 + +# This script cannot be spent, allowing dust output values under +# standardness checks +DUMMY_MIN_OP_RETURN_SCRIPT = CScript([OP_RETURN] + ([OP_0] * (MIN_PADDING - 1))) +assert len(DUMMY_MIN_OP_RETURN_SCRIPT) == MIN_PADDING def key_to_p2pk_script(key): key = check_key(key) |