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lnpeer: refuse to forward htlcs that correspond to payreq we created

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This commit is contained in:
SomberNight
2023-08-07 18:57:04 +00:00
parent cb907c90f9
commit c527ef8967
2 changed files with 91 additions and 6 deletions
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29
electrum/lnpeer.py
View File

@@ -1625,6 +1625,9 @@ class Peer(Logger):
except Exception:
raise OnionRoutingFailure(code=OnionFailureCode.INVALID_ONION_PAYLOAD, data=b'\x00\x00\x00')
if htlc.cltv_expiry - next_cltv_expiry < next_chan.forwarding_cltv_expiry_delta:
log_fail_reason(
f"INCORRECT_CLTV_EXPIRY. "
f"{htlc.cltv_expiry=} - {next_cltv_expiry=} < {next_chan.forwarding_cltv_expiry_delta=}")
data = htlc.cltv_expiry.to_bytes(4, byteorder="big") + outgoing_chan_upd_message
raise OnionRoutingFailure(code=OnionFailureCode.INCORRECT_CLTV_EXPIRY, data=data)
if htlc.cltv_expiry - lnutil.MIN_FINAL_CLTV_EXPIRY_ACCEPTED <= local_height \
@@ -1639,6 +1642,9 @@ class Peer(Logger):
if htlc.amount_msat - next_amount_msat_htlc < forwarding_fees:
data = next_amount_msat_htlc.to_bytes(8, byteorder="big") + outgoing_chan_upd_message
raise OnionRoutingFailure(code=OnionFailureCode.FEE_INSUFFICIENT, data=data)
if self._maybe_refuse_to_forward_htlc_that_corresponds_to_payreq_we_created(htlc.payment_hash):
log_fail_reason(f"RHASH corresponds to payreq we created")
raise OnionRoutingFailure(code=OnionFailureCode.TEMPORARY_NODE_FAILURE, data=b'')
self.logger.info(
f"maybe_forward_htlc. will forward HTLC: inc_chan={incoming_chan.short_channel_id}. inc_htlc={str(htlc)}. "
f"next_chan={next_chan.get_id_for_log()}.")
@@ -1707,6 +1713,12 @@ class Peer(Logger):
self.logger.exception('')
raise OnionRoutingFailure(code=OnionFailureCode.INVALID_ONION_PAYLOAD, data=b'\x00\x00\x00')
if self._maybe_refuse_to_forward_htlc_that_corresponds_to_payreq_we_created(payment_hash):
self.logger.debug(
f"maybe_forward_trampoline. will FAIL HTLC(s). "
f"RHASH corresponds to payreq we created. {payment_hash.hex()=}")
raise OnionRoutingFailure(code=OnionFailureCode.TEMPORARY_NODE_FAILURE, data=b'')
# these are the fee/cltv paid by the sender
# pay_to_node will raise if they are not sufficient
trampoline_cltv_delta = cltv_expiry - cltv_from_onion
@@ -1733,6 +1745,23 @@ class Peer(Logger):
# FIXME: adapt the error code
raise OnionRoutingFailure(code=OnionFailureCode.UNKNOWN_NEXT_PEER, data=b'')
def _maybe_refuse_to_forward_htlc_that_corresponds_to_payreq_we_created(self, payment_hash: bytes) -> bool:
"""Returns True if the HTLC should be failed.
We must not forward HTLCs with a matching payment_hash to a payment request we created.
Example attack:
- Bob creates payment request with HASH1, for 1 BTC; and gives the payreq to Alice
- Alice sends htlc A->B->C, for 1 sat, with HASH1
- Bob must not release the preimage of HASH1
"""
payment_info = self.lnworker.get_payment_info(payment_hash)
is_our_payreq = payment_info and payment_info.direction == RECEIVED
# note: If we don't have the preimage for a payment request, then it must be a hold invoice.
# Hold invoices are created by other parties (e.g. a counterparty initiating a submarine swap),
# and it is the other party choosing the payment_hash. If we failed HTLCs with payment_hashes colliding
# with hold invoices, then a party that can make us save a hold invoice for an arbitrary hash could
# also make us fail arbitrary HTLCs.
return bool(is_our_payreq and self.lnworker.get_preimage(payment_hash))
def maybe_fulfill_htlc(
self, *,
chan: Channel,

68
electrum/tests/test_lnpeer.py
View File

@@ -538,12 +538,17 @@ class TestPeer(ElectrumTestCase):
*,
amount_msat=100_000_000,
include_routing_hints=False,
payment_preimage: bytes = None,
payment_hash: bytes = None,
) -> Tuple[LnAddr, str]:
amount_btc = amount_msat/Decimal(COIN*1000)
payment_preimage = os.urandom(32)
RHASH = sha256(payment_preimage)
info = PaymentInfo(RHASH, amount_msat, RECEIVED, PR_UNPAID)
w2.save_preimage(RHASH, payment_preimage)
if payment_preimage is None and not payment_hash:
payment_preimage = os.urandom(32)
if payment_hash is None:
payment_hash = sha256(payment_preimage)
info = PaymentInfo(payment_hash, amount_msat, RECEIVED, PR_UNPAID)
if payment_preimage:
w2.save_preimage(payment_hash, payment_preimage)
w2.save_payment_info(info)
if include_routing_hints:
routing_hints, trampoline_hints = w2.calc_routing_hints_for_invoice(amount_msat)
@@ -552,11 +557,11 @@ class TestPeer(ElectrumTestCase):
trampoline_hints = []
invoice_features = w2.features.for_invoice()
if invoice_features.supports(LnFeatures.PAYMENT_SECRET_OPT):
payment_secret = w2.get_payment_secret(RHASH)
payment_secret = w2.get_payment_secret(payment_hash)
else:
payment_secret = None
lnaddr1 = LnAddr(
paymenthash=RHASH,
paymenthash=payment_hash,
amount=amount_btc,
tags=[('c', lnutil.MIN_FINAL_CLTV_EXPIRY_FOR_INVOICE),
('d', 'coffee'),
@@ -1046,6 +1051,57 @@ class TestPeer(ElectrumTestCase):
with self.assertRaises(PaymentDone):
await f()
async def test_refuse_to_forward_htlc_that_corresponds_to_payreq_we_created(self):
# This test checks that the following attack does not work:
# - Bob creates payment request with HASH1, for 1 BTC; and gives the payreq to Alice
# - Alice sends htlc A->B->D, for 100k sat, with HASH1
# - Bob must not release the preimage of HASH1
graph_def = self.GRAPH_DEFINITIONS['square_graph']
graph_def.pop('carol')
graph_def['alice']['channels'].pop('carol')
# now graph is linear: A <-> B <-> D
graph = self.prepare_chans_and_peers_in_graph(graph_def)
peers = graph.peers.values()
async def pay():
lnaddr1, pay_req1 = self.prepare_invoice(
graph.workers['bob'],
amount_msat=100_000_000_000,
)
lnaddr2, pay_req2 = self.prepare_invoice(
graph.workers['dave'],
amount_msat=100_000_000,
payment_hash=lnaddr1.paymenthash, # Dave is cooperating with Alice, and he reuses Bob's hash
include_routing_hints=True,
)
with self.subTest(msg="try to make Bob forward in legacy (non-trampoline) mode"):
result, log = await graph.workers['alice'].pay_invoice(pay_req2, attempts=1)
self.assertFalse(result)
self.assertEqual(OnionFailureCode.TEMPORARY_NODE_FAILURE, log[0].failure_msg.code)
self.assertEqual(None, graph.workers['alice'].get_preimage(lnaddr1.paymenthash))
with self.subTest(msg="try to make Bob forward in trampoline mode"):
# declare Bob as trampoline forwarding node
electrum.trampoline._TRAMPOLINE_NODES_UNITTESTS = {
graph.workers['bob'].name: LNPeerAddr(host="127.0.0.1", port=9735, pubkey=graph.workers['bob'].node_keypair.pubkey),
}
await self._activate_trampoline(graph.workers['alice'])
result, log = await graph.workers['alice'].pay_invoice(pay_req2, attempts=5)
self.assertFalse(result)
self.assertEqual(OnionFailureCode.TEMPORARY_NODE_FAILURE, log[0].failure_msg.code)
self.assertEqual(None, graph.workers['alice'].get_preimage(lnaddr1.paymenthash))
raise SuccessfulTest()
async def f():
async with OldTaskGroup() as group:
for peer in peers:
await group.spawn(peer._message_loop())
await group.spawn(peer.htlc_switch())
for peer in peers:
await peer.initialized
await group.spawn(pay())
with self.assertRaises(SuccessfulTest):
await f()
@needs_test_with_all_chacha20_implementations
async def test_payment_with_temp_channel_failure_and_liquidity_hints(self):
# prepare channels such that a temporary channel failure happens at c->d