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Merge #8312: Fix mempool DoS vulnerability from malleated transactions

46c9620 Test that unnecessary witnesses can't be used for mempool DoS (Suhas Daftuar)
bb66a11 Fix DoS vulnerability in mempool acceptance (Suhas Daftuar)
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laanwj committed Jul 14, 2016
2 parents 4324bd2 + 46c9620 commit ca40ef6029c1b4f2984e767b6c335dca6d637388
Showing with 56 additions and 8 deletions.
  1. +51 −3 qa/rpc-tests/p2p-segwit.py
  2. +5 −5 src/main.cpp
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@@ -43,6 +43,7 @@ def __init__(self):
self.last_pong = msg_pong(0)
self.sleep_time = 0.05
self.getdataset = set()
self.last_reject = None
def add_connection(self, conn):
self.connection = conn
@@ -68,7 +69,7 @@ def on_pong(self, conn, message):
def on_reject(self, conn, message):
self.last_reject = message
#print message
#print (message)
# Syncing helpers
def sync(self, test_function, timeout=60):
@@ -136,13 +137,17 @@ def request_block(self, blockhash, inv_type, timeout=60):
self.wait_for_block(blockhash, timeout)
return self.last_block
def test_transaction_acceptance(self, tx, with_witness, accepted):
def test_transaction_acceptance(self, tx, with_witness, accepted, reason=None):
tx_message = msg_tx(tx)
if with_witness:
tx_message = msg_witness_tx(tx)
self.send_message(tx_message)
self.sync_with_ping()
assert_equal(tx.hash in self.connection.rpc.getrawmempool(), accepted)
if (reason != None and not accepted):
# Check the rejection reason as well.
with mininode_lock:
assert_equal(self.last_reject.reason, reason)
# Test whether a witness block had the correct effect on the tip
def test_witness_block(self, block, accepted, with_witness=True):
@@ -277,9 +282,52 @@ def test_unnecessary_witness_before_segwit_activation(self):
self.test_node.sync_with_ping()
assert_equal(self.nodes[0].getbestblockhash(), block.hash)
sync_blocks(self.nodes)
# Create a p2sh output -- this is so we can pass the standardness
# rules (an anyone-can-spend OP_TRUE would be rejected, if not wrapped
# in P2SH).
p2sh_program = CScript([OP_TRUE])
p2sh_pubkey = hash160(p2sh_program)
scriptPubKey = CScript([OP_HASH160, p2sh_pubkey, OP_EQUAL])
# Now check that unnecessary witnesses can't be used to blind a node
# to a transaction, eg by violating standardness checks.
tx2 = CTransaction()
tx2.vin.append(CTxIn(COutPoint(tx.sha256, 0), b""))
tx2.vout.append(CTxOut(tx.vout[0].nValue-1000, scriptPubKey))
tx2.rehash()
self.test_node.test_transaction_acceptance(tx2, False, True)
self.nodes[0].generate(1)
sync_blocks(self.nodes)
# We'll add an unnecessary witness to this transaction that would cause
# it to be too large according to IsStandard.
tx3 = CTransaction()
tx3.vin.append(CTxIn(COutPoint(tx2.sha256, 0), CScript([p2sh_program])))
tx3.vout.append(CTxOut(tx2.vout[0].nValue-1000, scriptPubKey))
tx3.wit.vtxinwit.append(CTxinWitness())
tx3.wit.vtxinwit[0].scriptWitness.stack = [b'a'*400000]
tx3.rehash()
self.std_node.test_transaction_acceptance(tx3, True, False, b'no-witness-yet')
# If we send without witness, it should be accepted.
self.std_node.test_transaction_acceptance(tx3, False, True)
# Now create a new anyone-can-spend utxo for the next test.
tx4 = CTransaction()
tx4.vin.append(CTxIn(COutPoint(tx3.sha256, 0), CScript([p2sh_program])))
tx4.vout.append(CTxOut(tx3.vout[0].nValue-1000, CScript([OP_TRUE])))
tx4.rehash()
self.test_node.test_transaction_acceptance(tx3, False, True)
self.test_node.test_transaction_acceptance(tx4, False, True)
self.nodes[0].generate(1)
sync_blocks(self.nodes)
# Update our utxo list; we spent the first entry.
self.utxo.pop(0)
self.utxo.append(UTXO(tx.sha256, 0, tx.vout[0].nValue))
self.utxo.append(UTXO(tx4.sha256, 0, tx4.vout[0].nValue))
# Mine enough blocks for segwit's vb state to be 'started'.
View
@@ -1132,11 +1132,6 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState& state, const C
if (tx.IsCoinBase())
return state.DoS(100, false, REJECT_INVALID, "coinbase");
// Rather not work on nonstandard transactions (unless -testnet/-regtest)
string reason;
if (fRequireStandard && !IsStandardTx(tx, reason))
return state.DoS(0, false, REJECT_NONSTANDARD, reason);
// Don't relay version 2 transactions until CSV is active, and we can be
// sure that such transactions will be mined (unless we're on
// -testnet/-regtest).
@@ -1150,6 +1145,11 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState& state, const C
return state.DoS(0, false, REJECT_NONSTANDARD, "no-witness-yet", true);
}
// Rather not work on nonstandard transactions (unless -testnet/-regtest)
string reason;
if (fRequireStandard && !IsStandardTx(tx, reason))
return state.DoS(0, false, REJECT_NONSTANDARD, reason);
// Only accept nLockTime-using transactions that can be mined in the next
// block; we don't want our mempool filled up with transactions that can't
// be mined yet.

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