From 25f4a54a2bdda91232a62034befc3c6d20611058 Mon Sep 17 00:00:00 2001 From: Matt Corallo Date: Tue, 9 Nov 2021 21:25:33 +0000 Subject: [PATCH] Explicitly support counterparty setting 0 channel reserve A peer providing a channel_reserve_satoshis of 0 (or less than our dust limit) is insecure, but only for them. Because some LSPs do it with some level of trust of the clients (for a substantial UX improvement), we explicitly allow it. Because its unlikely to happen often in normal testing, we test it explicitly here. --- lightning/src/ln/channel.rs | 36 +++++++----- lightning/src/ln/channelmanager.rs | 2 +- lightning/src/ln/functional_test_utils.rs | 25 +++++--- lightning/src/ln/functional_tests.rs | 69 +++++++++++++++++++++-- 4 files changed, 104 insertions(+), 28 deletions(-) diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs index 9b91a1ad..ae5df9a1 100644 --- a/lightning/src/ln/channel.rs +++ b/lightning/src/ln/channel.rs @@ -387,9 +387,9 @@ pub(super) struct MonitorRestoreUpdates { /// the channel. Sadly, there isn't really a good number for this - if we expect to have no new /// HTLCs for days we may need this to suffice for feerate increases across days, but that may /// leave the channel less usable as we hold a bigger reserve. -#[cfg(fuzzing)] +#[cfg(any(fuzzing, test))] pub const FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE: u64 = 2; -#[cfg(not(fuzzing))] +#[cfg(not(any(fuzzing, test)))] const FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE: u64 = 2; /// If we fail to see a funding transaction confirmed on-chain within this many blocks after the @@ -516,19 +516,30 @@ pub(super) struct Channel { channel_creation_height: u32, counterparty_dust_limit_satoshis: u64, + #[cfg(test)] pub(super) holder_dust_limit_satoshis: u64, #[cfg(not(test))] holder_dust_limit_satoshis: u64, + #[cfg(test)] pub(super) counterparty_max_htlc_value_in_flight_msat: u64, #[cfg(not(test))] counterparty_max_htlc_value_in_flight_msat: u64, + + #[cfg(test)] + pub(super) holder_max_htlc_value_in_flight_msat: u64, + #[cfg(not(test))] holder_max_htlc_value_in_flight_msat: u64, /// minimum channel reserve for self to maintain - set by them. counterparty_selected_channel_reserve_satoshis: Option, + + #[cfg(test)] + pub(super) holder_selected_channel_reserve_satoshis: u64, + #[cfg(not(test))] holder_selected_channel_reserve_satoshis: u64, + counterparty_htlc_minimum_msat: u64, holder_htlc_minimum_msat: u64, #[cfg(test)] @@ -868,12 +879,13 @@ impl Channel { /// Creates a new channel from a remote sides' request for one. /// Assumes chain_hash has already been checked and corresponds with what we expect! - pub fn new_from_req( + pub fn new_from_req( fee_estimator: &F, keys_provider: &K, counterparty_node_id: PublicKey, their_features: &InitFeatures, - msg: &msgs::OpenChannel, user_id: u64, config: &UserConfig, current_chain_height: u32 + msg: &msgs::OpenChannel, user_id: u64, config: &UserConfig, current_chain_height: u32, logger: &L ) -> Result, ChannelError> where K::Target: KeysInterface, - F::Target: FeeEstimator + F::Target: FeeEstimator, + L::Target: Logger, { // First check the channel type is known, failing before we do anything else if we don't // support this channel type. @@ -921,9 +933,6 @@ impl Channel { if msg.dust_limit_satoshis > msg.funding_satoshis { return Err(ChannelError::Close(format!("dust_limit_satoshis {} was larger than funding_satoshis {}. Peer never wants payout outputs?", msg.dust_limit_satoshis, msg.funding_satoshis))); } - if msg.dust_limit_satoshis > msg.channel_reserve_satoshis { - return Err(ChannelError::Close(format!("Bogus; channel reserve ({}) is less than dust limit ({})", msg.channel_reserve_satoshis, msg.dust_limit_satoshis))); - } let full_channel_value_msat = (msg.funding_satoshis - msg.channel_reserve_satoshis) * 1000; if msg.htlc_minimum_msat >= full_channel_value_msat { return Err(ChannelError::Close(format!("Minimum htlc value ({}) was larger than full channel value ({})", msg.htlc_minimum_msat, full_channel_value_msat))); @@ -980,7 +989,8 @@ impl Channel { return Err(ChannelError::Close(format!("Suitable channel reserve not found. remote_channel_reserve was ({}). dust_limit_satoshis is ({}).", holder_selected_channel_reserve_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS))); } if msg.channel_reserve_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS { - return Err(ChannelError::Close(format!("channel_reserve_satoshis ({}) is smaller than our dust limit ({})", msg.channel_reserve_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS))); + log_debug!(logger, "channel_reserve_satoshis ({}) is smaller than our dust limit ({}). We can broadcast stale states without any risk, implying this channel is very insecure for our counterparty.", + msg.channel_reserve_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS); } if holder_selected_channel_reserve_satoshis < msg.dust_limit_satoshis { return Err(ChannelError::Close(format!("Dust limit ({}) too high for the channel reserve we require the remote to keep ({})", msg.dust_limit_satoshis, holder_selected_channel_reserve_satoshis))); @@ -1712,9 +1722,6 @@ impl Channel { if msg.channel_reserve_satoshis > self.channel_value_satoshis { return Err(ChannelError::Close(format!("Bogus channel_reserve_satoshis ({}). Must not be greater than ({})", msg.channel_reserve_satoshis, self.channel_value_satoshis))); } - if msg.channel_reserve_satoshis < self.holder_dust_limit_satoshis { - return Err(ChannelError::Close(format!("Peer never wants payout outputs? channel_reserve_satoshis was ({}). dust_limit is ({})", msg.channel_reserve_satoshis, self.holder_dust_limit_satoshis))); - } if msg.dust_limit_satoshis > self.holder_selected_channel_reserve_satoshis { return Err(ChannelError::Close(format!("Dust limit ({}) is bigger than our channel reserve ({})", msg.dust_limit_satoshis, self.holder_selected_channel_reserve_satoshis))); } @@ -5912,6 +5919,7 @@ mod tests { let seed = [42; 32]; let network = Network::Testnet; let keys_provider = test_utils::TestKeysInterface::new(&seed, network); + let logger = test_utils::TestLogger::new(); // Go through the flow of opening a channel between two nodes, making sure // they have different dust limits. @@ -5925,7 +5933,7 @@ mod tests { // Make sure A's dust limit is as we expect. let open_channel_msg = node_a_chan.get_open_channel(genesis_block(network).header.block_hash()); let node_b_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[7; 32]).unwrap()); - let node_b_chan = Channel::::new_from_req(&&feeest, &&keys_provider, node_b_node_id, &InitFeatures::known(), &open_channel_msg, 7, &config, 0).unwrap(); + let node_b_chan = Channel::::new_from_req(&&feeest, &&keys_provider, node_b_node_id, &InitFeatures::known(), &open_channel_msg, 7, &config, 0, &&logger).unwrap(); // Node B --> Node A: accept channel, explicitly setting B's dust limit. let mut accept_channel_msg = node_b_chan.get_accept_channel(); @@ -6043,7 +6051,7 @@ mod tests { // Create Node B's channel by receiving Node A's open_channel message let open_channel_msg = node_a_chan.get_open_channel(chain_hash); let node_b_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[7; 32]).unwrap()); - let mut node_b_chan = Channel::::new_from_req(&&feeest, &&keys_provider, node_b_node_id, &InitFeatures::known(), &open_channel_msg, 7, &config, 0).unwrap(); + let mut node_b_chan = Channel::::new_from_req(&&feeest, &&keys_provider, node_b_node_id, &InitFeatures::known(), &open_channel_msg, 7, &config, 0, &&logger).unwrap(); // Node B --> Node A: accept channel let accept_channel_msg = node_b_chan.get_accept_channel(); diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs index e0bcd089..0eaf244d 100644 --- a/lightning/src/ln/channelmanager.rs +++ b/lightning/src/ln/channelmanager.rs @@ -3683,7 +3683,7 @@ impl ChannelMana } let channel = Channel::new_from_req(&self.fee_estimator, &self.keys_manager, counterparty_node_id.clone(), - &their_features, msg, 0, &self.default_configuration, self.best_block.read().unwrap().height()) + &their_features, msg, 0, &self.default_configuration, self.best_block.read().unwrap().height(), &self.logger) .map_err(|e| MsgHandleErrInternal::from_chan_no_close(e, msg.temporary_channel_id))?; let mut channel_state_lock = self.channel_state.lock().unwrap(); let channel_state = &mut *channel_state_lock; diff --git a/lightning/src/ln/functional_test_utils.rs b/lightning/src/ln/functional_test_utils.rs index bf3e192b..01f9db53 100644 --- a/lightning/src/ln/functional_test_utils.rs +++ b/lightning/src/ln/functional_test_utils.rs @@ -526,19 +526,16 @@ pub fn create_funding_transaction<'a, 'b, 'c>(node: &Node<'a, 'b, 'c>, expected_ _ => panic!("Unexpected event"), } } - -pub fn create_chan_between_nodes_with_value_init<'a, 'b, 'c>(node_a: &Node<'a, 'b, 'c>, node_b: &Node<'a, 'b, 'c>, channel_value: u64, push_msat: u64, a_flags: InitFeatures, b_flags: InitFeatures) -> Transaction { - let create_chan_id = node_a.node.create_channel(node_b.node.get_our_node_id(), channel_value, push_msat, 42, None).unwrap(); - node_b.node.handle_open_channel(&node_a.node.get_our_node_id(), a_flags, &get_event_msg!(node_a, MessageSendEvent::SendOpenChannel, node_b.node.get_our_node_id())); - node_a.node.handle_accept_channel(&node_b.node.get_our_node_id(), b_flags, &get_event_msg!(node_b, MessageSendEvent::SendAcceptChannel, node_a.node.get_our_node_id())); - +pub fn sign_funding_transaction<'a, 'b, 'c>(node_a: &Node<'a, 'b, 'c>, node_b: &Node<'a, 'b, 'c>, channel_value: u64, expected_temporary_channel_id: [u8; 32]) -> Transaction { let (temporary_channel_id, tx, funding_output) = create_funding_transaction(node_a, channel_value, 42); - assert_eq!(temporary_channel_id, create_chan_id); + assert_eq!(temporary_channel_id, expected_temporary_channel_id); node_a.node.funding_transaction_generated(&temporary_channel_id, tx.clone()).unwrap(); check_added_monitors!(node_a, 0); - node_b.node.handle_funding_created(&node_a.node.get_our_node_id(), &get_event_msg!(node_a, MessageSendEvent::SendFundingCreated, node_b.node.get_our_node_id())); + let funding_created_msg = get_event_msg!(node_a, MessageSendEvent::SendFundingCreated, node_b.node.get_our_node_id()); + assert_eq!(funding_created_msg.temporary_channel_id, expected_temporary_channel_id); + node_b.node.handle_funding_created(&node_a.node.get_our_node_id(), &funding_created_msg); { let mut added_monitors = node_b.chain_monitor.added_monitors.lock().unwrap(); assert_eq!(added_monitors.len(), 1); @@ -564,6 +561,18 @@ pub fn create_chan_between_nodes_with_value_init<'a, 'b, 'c>(node_a: &Node<'a, ' tx } +pub fn create_chan_between_nodes_with_value_init<'a, 'b, 'c>(node_a: &Node<'a, 'b, 'c>, node_b: &Node<'a, 'b, 'c>, channel_value: u64, push_msat: u64, a_flags: InitFeatures, b_flags: InitFeatures) -> Transaction { + let create_chan_id = node_a.node.create_channel(node_b.node.get_our_node_id(), channel_value, push_msat, 42, None).unwrap(); + let open_channel_msg = get_event_msg!(node_a, MessageSendEvent::SendOpenChannel, node_b.node.get_our_node_id()); + assert_eq!(open_channel_msg.temporary_channel_id, create_chan_id); + node_b.node.handle_open_channel(&node_a.node.get_our_node_id(), a_flags, &open_channel_msg); + let accept_channel_msg = get_event_msg!(node_b, MessageSendEvent::SendAcceptChannel, node_a.node.get_our_node_id()); + assert_eq!(accept_channel_msg.temporary_channel_id, create_chan_id); + node_a.node.handle_accept_channel(&node_b.node.get_our_node_id(), b_flags, &accept_channel_msg); + + sign_funding_transaction(node_a, node_b, channel_value, create_chan_id) +} + pub fn create_chan_between_nodes_with_value_confirm_first<'a, 'b, 'c, 'd>(node_recv: &'a Node<'b, 'c, 'c>, node_conf: &'a Node<'b, 'c, 'd>, tx: &Transaction, conf_height: u32) { confirm_transaction_at(node_conf, tx, conf_height); connect_blocks(node_conf, CHAN_CONFIRM_DEPTH - 1); diff --git a/lightning/src/ln/functional_tests.rs b/lightning/src/ln/functional_tests.rs index f144dbd9..48d56b43 100644 --- a/lightning/src/ln/functional_tests.rs +++ b/lightning/src/ln/functional_tests.rs @@ -18,7 +18,7 @@ use chain::channelmonitor::{ChannelMonitor, CLTV_CLAIM_BUFFER, LATENCY_GRACE_PER use chain::transaction::OutPoint; use chain::keysinterface::BaseSign; use ln::{PaymentPreimage, PaymentSecret, PaymentHash}; -use ln::channel::{COMMITMENT_TX_BASE_WEIGHT, COMMITMENT_TX_WEIGHT_PER_HTLC, CONCURRENT_INBOUND_HTLC_FEE_BUFFER, MIN_AFFORDABLE_HTLC_COUNT}; +use ln::channel::{COMMITMENT_TX_BASE_WEIGHT, COMMITMENT_TX_WEIGHT_PER_HTLC, CONCURRENT_INBOUND_HTLC_FEE_BUFFER, FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE, MIN_AFFORDABLE_HTLC_COUNT}; use ln::channelmanager::{ChannelManager, ChannelManagerReadArgs, PaymentId, RAACommitmentOrder, PaymentSendFailure, BREAKDOWN_TIMEOUT, MIN_CLTV_EXPIRY_DELTA}; use ln::channel::{Channel, ChannelError}; use ln::{chan_utils, onion_utils}; @@ -108,8 +108,6 @@ fn test_insane_channel_opens() { insane_open_helper("Peer never wants payout outputs?", |mut msg| { msg.dust_limit_satoshis = msg.funding_satoshis + 1 ; msg }); - insane_open_helper(r"Bogus; channel reserve \(\d+\) is less than dust limit \(\d+\)", |mut msg| { msg.dust_limit_satoshis = msg.channel_reserve_satoshis + 1; msg }); - insane_open_helper(r"Minimum htlc value \(\d+\) was larger than full channel value \(\d+\)", |mut msg| { msg.htlc_minimum_msat = (msg.funding_satoshis - msg.channel_reserve_satoshis) * 1000; msg }); insane_open_helper("They wanted our payments to be delayed by a needlessly long period", |mut msg| { msg.to_self_delay = MAX_LOCAL_BREAKDOWN_TIMEOUT + 1; msg }); @@ -119,6 +117,67 @@ fn test_insane_channel_opens() { insane_open_helper("max_accepted_htlcs was 484. It must not be larger than 483", |mut msg| { msg.max_accepted_htlcs = 484; msg }); } +fn do_test_counterparty_no_reserve(send_from_initiator: bool) { + // A peer providing a channel_reserve_satoshis of 0 (or less than our dust limit) is insecure, + // but only for them. Because some LSPs do it with some level of trust of the clients (for a + // substantial UX improvement), we explicitly allow it. Because it's unlikely to happen often + // in normal testing, we test it explicitly here. + let chanmon_cfgs = create_chanmon_cfgs(2); + let node_cfgs = create_node_cfgs(2, &chanmon_cfgs); + let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]); + let nodes = create_network(2, &node_cfgs, &node_chanmgrs); + + // Have node0 initiate a channel to node1 with aforementioned parameters + let mut push_amt = 100_000_000; + let feerate_per_kw = 253; + push_amt -= feerate_per_kw as u64 * (COMMITMENT_TX_BASE_WEIGHT + 4 * COMMITMENT_TX_WEIGHT_PER_HTLC) / 1000 * 1000; + push_amt -= Channel::::get_holder_selected_channel_reserve_satoshis(100_000) * 1000; + + let temp_channel_id = nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 100_000, if send_from_initiator { 0 } else { push_amt }, 42, None).unwrap(); + let mut open_channel_message = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id()); + if !send_from_initiator { + open_channel_message.channel_reserve_satoshis = 0; + open_channel_message.max_htlc_value_in_flight_msat = 100_000_000; + } + nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), InitFeatures::known(), &open_channel_message); + + // Extract the channel accept message from node1 to node0 + let mut accept_channel_message = get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, nodes[0].node.get_our_node_id()); + if send_from_initiator { + accept_channel_message.channel_reserve_satoshis = 0; + accept_channel_message.max_htlc_value_in_flight_msat = 100_000_000; + } + nodes[0].node.handle_accept_channel(&nodes[1].node.get_our_node_id(), InitFeatures::known(), &accept_channel_message); + { + let mut lock; + let mut chan = get_channel_ref!(if send_from_initiator { &nodes[1] } else { &nodes[0] }, lock, temp_channel_id); + chan.holder_selected_channel_reserve_satoshis = 0; + chan.holder_max_htlc_value_in_flight_msat = 100_000_000; + } + + let funding_tx = sign_funding_transaction(&nodes[0], &nodes[1], 100_000, temp_channel_id); + let funding_msgs = create_chan_between_nodes_with_value_confirm(&nodes[0], &nodes[1], &funding_tx); + create_chan_between_nodes_with_value_b(&nodes[0], &nodes[1], &funding_msgs.0); + + // nodes[0] should now be able to send the full balance to nodes[1], violating nodes[1]'s + // security model if it ever tries to send funds back to nodes[0] (but that's not our problem). + if send_from_initiator { + send_payment(&nodes[0], &[&nodes[1]], 100_000_000 + // Note that for outbound channels we have to consider the commitment tx fee and the + // "fee spike buffer", which is currently a multiple of the total commitment tx fee as + // well as an additional HTLC. + - FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE * commit_tx_fee_msat(feerate_per_kw, 2)); + } else { + send_payment(&nodes[1], &[&nodes[0]], push_amt); + } +} + +#[test] +fn test_counterparty_no_reserve() { + do_test_counterparty_no_reserve(true); + do_test_counterparty_no_reserve(false); +} + #[test] fn test_async_inbound_update_fee() { let chanmon_cfgs = create_chanmon_cfgs(2); @@ -7089,7 +7148,7 @@ fn test_user_configurable_csv_delay() { nodes[1].node.create_channel(nodes[0].node.get_our_node_id(), 1000000, 1000000, 42, None).unwrap(); let mut open_channel = get_event_msg!(nodes[1], MessageSendEvent::SendOpenChannel, nodes[0].node.get_our_node_id()); open_channel.to_self_delay = 200; - if let Err(error) = Channel::new_from_req(&&test_utils::TestFeeEstimator { sat_per_kw: Mutex::new(253) }, &nodes[0].keys_manager, nodes[1].node.get_our_node_id(), &InitFeatures::known(), &open_channel, 0, &low_our_to_self_config, 0) { + if let Err(error) = Channel::new_from_req(&&test_utils::TestFeeEstimator { sat_per_kw: Mutex::new(253) }, &nodes[0].keys_manager, nodes[1].node.get_our_node_id(), &InitFeatures::known(), &open_channel, 0, &low_our_to_self_config, 0, &nodes[0].logger) { match error { ChannelError::Close(err) => { assert!(regex::Regex::new(r"Configured with an unreasonable our_to_self_delay \(\d+\) putting user funds at risks").unwrap().is_match(err.as_str())); }, _ => panic!("Unexpected event"), @@ -7118,7 +7177,7 @@ fn test_user_configurable_csv_delay() { nodes[1].node.create_channel(nodes[0].node.get_our_node_id(), 1000000, 1000000, 42, None).unwrap(); let mut open_channel = get_event_msg!(nodes[1], MessageSendEvent::SendOpenChannel, nodes[0].node.get_our_node_id()); open_channel.to_self_delay = 200; - if let Err(error) = Channel::new_from_req(&&test_utils::TestFeeEstimator { sat_per_kw: Mutex::new(253) }, &nodes[0].keys_manager, nodes[1].node.get_our_node_id(), &InitFeatures::known(), &open_channel, 0, &high_their_to_self_config, 0) { + if let Err(error) = Channel::new_from_req(&&test_utils::TestFeeEstimator { sat_per_kw: Mutex::new(253) }, &nodes[0].keys_manager, nodes[1].node.get_our_node_id(), &InitFeatures::known(), &open_channel, 0, &high_their_to_self_config, 0, &nodes[0].logger) { match error { ChannelError::Close(err) => { assert!(regex::Regex::new(r"They wanted our payments to be delayed by a needlessly long period\. Upper limit: \d+\. Actual: \d+").unwrap().is_match(err.as_str())); }, _ => panic!("Unexpected event"), -- 2.30.2