X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fln%2Fonion_payment.rs;h=5966dce91039db227155264deb0557a2ed2012ff;hb=c80d9a74b5437dd7c82fab40806adeb995219fc2;hp=5ea07cfab30db4325bc71415f1b3f331ca1a37dc;hpb=339f3fccf80c8ccfc8de936df8de65481586f833;p=rust-lightning

diff --git a/lightning/src/ln/onion_payment.rs b/lightning/src/ln/onion_payment.rs
index 5ea07cfa..5966dce9 100644
--- a/lightning/src/ln/onion_payment.rs
+++ b/lightning/src/ln/onion_payment.rs
@@ -24,6 +24,7 @@ use crate::prelude::*;
 use core::ops::Deref;
 
 /// Invalid inbound onion payment.
+#[derive(Debug)]
 pub struct InboundOnionErr {
 	/// BOLT 4 error code.
 	pub err_code: u16,
@@ -33,6 +34,15 @@ pub struct InboundOnionErr {
 	pub msg: &'static str,
 }
 
+fn check_blinded_payment_constraints(
+	amt_msat: u64, cltv_expiry: u32, constraints: &PaymentConstraints
+) -> Result<(), ()> {
+	if amt_msat < constraints.htlc_minimum_msat ||
+		cltv_expiry > constraints.max_cltv_expiry
+	{ return Err(()) }
+	Ok(())
+}
+
 fn check_blinded_forward(
 	inbound_amt_msat: u64, inbound_cltv_expiry: u32, payment_relay: &PaymentRelay,
 	payment_constraints: &PaymentConstraints, features: &BlindedHopFeatures
@@ -43,9 +53,8 @@ fn check_blinded_forward(
 	let outgoing_cltv_value = inbound_cltv_expiry.checked_sub(
 		payment_relay.cltv_expiry_delta as u32
 	).ok_or(())?;
-	if inbound_amt_msat < payment_constraints.htlc_minimum_msat ||
-		outgoing_cltv_value > payment_constraints.max_cltv_expiry
-		{ return Err(()) }
+	check_blinded_payment_constraints(inbound_amt_msat, outgoing_cltv_value, payment_constraints)?;
+
 	if features.requires_unknown_bits_from(&BlindedHopFeatures::empty()) { return Err(()) }
 	Ok((amt_to_forward, outgoing_cltv_value))
 }
@@ -122,8 +131,17 @@ pub(super) fn create_recv_pending_htlc_info(
 			(payment_data, keysend_preimage, custom_tlvs, amt_msat, outgoing_cltv_value, payment_metadata,
 			 false),
 		msgs::InboundOnionPayload::BlindedReceive {
-			amt_msat, total_msat, outgoing_cltv_value, payment_secret, intro_node_blinding_point, ..
+			amt_msat, total_msat, outgoing_cltv_value, payment_secret, intro_node_blinding_point,
+			payment_constraints, ..
 		} => {
+			check_blinded_payment_constraints(amt_msat, cltv_expiry, &payment_constraints)
+				.map_err(|()| {
+					InboundOnionErr {
+						err_code: INVALID_ONION_BLINDING,
+						err_data: vec![0; 32],
+						msg: "Amount or cltv_expiry violated blinded payment constraints",
+					}
+				})?;
 			let payment_data = msgs::FinalOnionHopData { payment_secret, total_msat };
 			(Some(payment_data), None, Vec::new(), amt_msat, outgoing_cltv_value, None,
 			 intro_node_blinding_point.is_none())
@@ -319,11 +337,16 @@ where
 		($msg: expr, $err_code: expr) => {
 			{
 				log_info!(logger, "Failed to accept/forward incoming HTLC: {}", $msg);
+				let (sha256_of_onion, failure_code) = if msg.blinding_point.is_some() {
+					([0; 32], INVALID_ONION_BLINDING)
+				} else {
+					(Sha256::hash(&msg.onion_routing_packet.hop_data).to_byte_array(), $err_code)
+				};
 				return Err(HTLCFailureMsg::Malformed(msgs::UpdateFailMalformedHTLC {
 					channel_id: msg.channel_id,
 					htlc_id: msg.htlc_id,
-					sha256_of_onion: Sha256::hash(&msg.onion_routing_packet.hop_data).to_byte_array(),
-					failure_code: $err_code,
+					sha256_of_onion,
+					failure_code,
 				}));
 			}
 		}
@@ -355,6 +378,10 @@ where
 	macro_rules! return_err {
 		($msg: expr, $err_code: expr, $data: expr) => {
 			{
+				if msg.blinding_point.is_some() {
+					return_malformed_err!($msg, INVALID_ONION_BLINDING)
+				}
+
 				log_info!(logger, "Failed to accept/forward incoming HTLC: {}", $msg);
 				return Err(HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
 					channel_id: msg.channel_id,
@@ -461,7 +488,7 @@ pub(super) fn check_incoming_htlc_cltv(
 mod tests {
 	use bitcoin::hashes::Hash;
 	use bitcoin::hashes::sha256::Hash as Sha256;
-	use bitcoin::secp256k1::{PublicKey, SecretKey};
+	use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
 	use crate::ln::{PaymentPreimage, PaymentHash, PaymentSecret};
 	use crate::ln::ChannelId;
 	use crate::ln::channelmanager::RecipientOnionFields;
@@ -471,6 +498,38 @@ mod tests {
 	use crate::routing::router::{Path, RouteHop};
 	use crate::util::test_utils;
 
+	#[test]
+	fn fail_construct_onion_on_too_big_payloads() {
+		// Ensure that if we call `construct_onion_packet` and friends where payloads are too large for
+		// the allotted packet length, we'll fail to construct. Previously, senders would happily
+		// construct invalid packets by array-shifting the final node's HMAC out of the packet when
+		// adding an intermediate onion layer, causing the receiver to error with "final payload
+		// provided for us as an intermediate node."
+		let secp_ctx = Secp256k1::new();
+		let bob = crate::sign::KeysManager::new(&[2; 32], 42, 42);
+		let bob_pk = PublicKey::from_secret_key(&secp_ctx, &bob.get_node_secret_key());
+		let charlie = crate::sign::KeysManager::new(&[3; 32], 42, 42);
+		let charlie_pk = PublicKey::from_secret_key(&secp_ctx, &charlie.get_node_secret_key());
+
+		let (
+			session_priv, total_amt_msat, cur_height, mut recipient_onion, keysend_preimage, payment_hash,
+			prng_seed, hops, ..
+		) = payment_onion_args(bob_pk, charlie_pk);
+
+		// Ensure the onion will not fit all the payloads by adding a large custom TLV.
+		recipient_onion.custom_tlvs.push((13377331, vec![0; 1156]));
+
+		let path = Path { hops, blinded_tail: None, };
+		let onion_keys = super::onion_utils::construct_onion_keys(&secp_ctx, &path, &session_priv).unwrap();
+		let (onion_payloads, ..) = super::onion_utils::build_onion_payloads(
+			&path, total_amt_msat, recipient_onion, cur_height + 1, &Some(keysend_preimage)
+		).unwrap();
+
+		assert!(super::onion_utils::construct_onion_packet(
+				onion_payloads, onion_keys, prng_seed, &payment_hash
+		).is_err());
+	}
+
 	#[test]
 	fn test_peel_payment_onion() {
 		use super::*;