From e8854a9ce26112705c308060b3485b69f894666e Mon Sep 17 00:00:00 2001 From: =?utf8?q?Viktor=20Tigerstr=C3=B6m?= <11711198+ViktorTigerstrom@users.noreply.github.com> Date: Mon, 8 Aug 2022 21:54:06 +0200 Subject: [PATCH] Remove unnecessary aquiring of the `channel_state` lock --- lightning/src/ln/channelmanager.rs | 103 +++++++++++++++-------------- 1 file changed, 52 insertions(+), 51 deletions(-) diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs index 39866d3d8..cce6a7f97 100644 --- a/lightning/src/ln/channelmanager.rs +++ b/lightning/src/ln/channelmanager.rs @@ -1887,7 +1887,7 @@ impl ChannelMana for htlc_source in failed_htlcs.drain(..) { let receiver = HTLCDestination::NextHopChannel { node_id: Some(*counterparty_node_id), channel_id: *channel_id }; - self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), htlc_source.0, &htlc_source.1, HTLCFailReason::Reason { failure_code: 0x4000 | 8, data: Vec::new() }, receiver); + self.fail_htlc_backwards_internal(htlc_source.0, &htlc_source.1, HTLCFailReason::Reason { failure_code: 0x4000 | 8, data: Vec::new() }, receiver); } let _ = handle_error!(self, result, *counterparty_node_id); @@ -1945,7 +1945,7 @@ impl ChannelMana for htlc_source in failed_htlcs.drain(..) { let (source, payment_hash, counterparty_node_id, channel_id) = htlc_source; let receiver = HTLCDestination::NextHopChannel { node_id: Some(counterparty_node_id), channel_id: channel_id }; - self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), source, &payment_hash, HTLCFailReason::Reason { failure_code: 0x4000 | 8, data: Vec::new() }, receiver); + self.fail_htlc_backwards_internal(source, &payment_hash, HTLCFailReason::Reason { failure_code: 0x4000 | 8, data: Vec::new() }, receiver); } if let Some((funding_txo, monitor_update)) = monitor_update_option { // There isn't anything we can do if we get an update failure - we're already @@ -3005,13 +3005,12 @@ impl ChannelMana let mut phantom_receives: Vec<(u64, OutPoint, Vec<(PendingHTLCInfo, u64)>)> = Vec::new(); let mut handle_errors = Vec::new(); { - let mut channel_state_lock = self.channel_state.lock().unwrap(); - let channel_state = &mut *channel_state_lock; - let mut forward_htlcs = HashMap::new(); mem::swap(&mut forward_htlcs, &mut self.forward_htlcs.lock().unwrap()); for (short_chan_id, mut pending_forwards) in forward_htlcs { + let mut channel_state_lock = self.channel_state.lock().unwrap(); + let channel_state = &mut *channel_state_lock; if short_chan_id != 0 { let forward_chan_id = match channel_state.short_to_chan_info.get(&short_chan_id) { Some((_cp_id, chan_id)) => chan_id.clone(), @@ -3409,7 +3408,7 @@ impl ChannelMana } for (htlc_source, payment_hash, failure_reason, destination) in failed_forwards.drain(..) { - self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), htlc_source, &payment_hash, failure_reason, destination); + self.fail_htlc_backwards_internal(htlc_source, &payment_hash, failure_reason, destination); } self.forward_htlcs(&mut phantom_receives); @@ -3633,7 +3632,7 @@ impl ChannelMana for htlc_source in timed_out_mpp_htlcs.drain(..) { let receiver = HTLCDestination::FailedPayment { payment_hash: htlc_source.1 }; - self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), HTLCSource::PreviousHopData(htlc_source.0.clone()), &htlc_source.1, HTLCFailReason::Reason { failure_code: 23, data: Vec::new() }, receiver ); + self.fail_htlc_backwards_internal(HTLCSource::PreviousHopData(htlc_source.0.clone()), &htlc_source.1, HTLCFailReason::Reason { failure_code: 23, data: Vec::new() }, receiver ); } for (err, counterparty_node_id) in handle_errors.drain(..) { @@ -3659,15 +3658,16 @@ impl ChannelMana pub fn fail_htlc_backwards(&self, payment_hash: &PaymentHash) { let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier); - let mut channel_state = Some(self.channel_state.lock().unwrap()); - let removed_source = channel_state.as_mut().unwrap().claimable_htlcs.remove(payment_hash); + let removed_source = { + let mut channel_state = self.channel_state.lock().unwrap(); + channel_state.claimable_htlcs.remove(payment_hash) + }; if let Some((_, mut sources)) = removed_source { for htlc in sources.drain(..) { - if channel_state.is_none() { channel_state = Some(self.channel_state.lock().unwrap()); } let mut htlc_msat_height_data = byte_utils::be64_to_array(htlc.value).to_vec(); htlc_msat_height_data.extend_from_slice(&byte_utils::be32_to_array( self.best_block.read().unwrap().height())); - self.fail_htlc_backwards_internal(channel_state.take().unwrap(), + self.fail_htlc_backwards_internal( HTLCSource::PreviousHopData(htlc.prev_hop), payment_hash, HTLCFailReason::Reason { failure_code: 0x4000 | 15, data: htlc_msat_height_data }, HTLCDestination::FailedPayment { payment_hash: *payment_hash }); @@ -3730,9 +3730,8 @@ impl ChannelMana counterparty_node_id: &PublicKey ) { for (htlc_src, payment_hash) in htlcs_to_fail.drain(..) { - let mut channel_state = self.channel_state.lock().unwrap(); let (failure_code, onion_failure_data) = - match channel_state.by_id.entry(channel_id) { + match self.channel_state.lock().unwrap().by_id.entry(channel_id) { hash_map::Entry::Occupied(chan_entry) => { self.get_htlc_inbound_temp_fail_err_and_data(0x1000|7, &chan_entry.get()) }, @@ -3740,17 +3739,22 @@ impl ChannelMana }; let receiver = HTLCDestination::NextHopChannel { node_id: Some(counterparty_node_id.clone()), channel_id }; - self.fail_htlc_backwards_internal(channel_state, htlc_src, &payment_hash, HTLCFailReason::Reason { failure_code, data: onion_failure_data }, receiver); + self.fail_htlc_backwards_internal(htlc_src, &payment_hash, HTLCFailReason::Reason { failure_code, data: onion_failure_data }, receiver); } } /// Fails an HTLC backwards to the sender of it to us. - /// Note that while we take a channel_state lock as input, we do *not* assume consistency here. - /// There are several callsites that do stupid things like loop over a list of payment_hashes - /// to fail and take the channel_state lock for each iteration (as we take ownership and may - /// drop it). In other words, no assumptions are made that entries in claimable_htlcs point to - /// still-available channels. - fn fail_htlc_backwards_internal(&self, mut channel_state_lock: MutexGuard>, source: HTLCSource, payment_hash: &PaymentHash, onion_error: HTLCFailReason, destination: HTLCDestination) { + /// Note that we do not assume that channels corresponding to failed HTLCs are still available. + fn fail_htlc_backwards_internal(&self, source: HTLCSource, payment_hash: &PaymentHash, onion_error: HTLCFailReason,destination: HTLCDestination) { + #[cfg(debug_assertions)] + { + // Ensure that the `channel_state` lock is not held when calling this function. + // This ensures that future code doesn't introduce a lock_order requirement for + // `forward_htlcs` to be locked after the `channel_state` lock, which calling this + // function with the `channel_state` locked would. + assert!(self.channel_state.try_lock().is_ok()); + } + //TODO: There is a timing attack here where if a node fails an HTLC back to us they can //identify whether we sent it or not based on the (I presume) very different runtime //between the branches here. We should make this async and move it into the forward HTLCs @@ -3789,7 +3793,6 @@ impl ChannelMana log_trace!(self.logger, "Received duplicative fail for HTLC with payment_hash {}", log_bytes!(payment_hash.0)); return; } - mem::drop(channel_state_lock); let mut retry = if let Some(payment_params_data) = payment_params { let path_last_hop = path.last().expect("Outbound payments must have had a valid path"); Some(RouteParameters { @@ -3923,7 +3926,6 @@ impl ChannelMana } } mem::drop(forward_htlcs); - mem::drop(channel_state_lock); let mut pending_events = self.pending_events.lock().unwrap(); if let Some(time) = forward_event { pending_events.push(events::Event::PendingHTLCsForwardable { @@ -3961,8 +3963,7 @@ impl ChannelMana let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier); - let mut channel_state = Some(self.channel_state.lock().unwrap()); - let removed_source = channel_state.as_mut().unwrap().claimable_htlcs.remove(&payment_hash); + let removed_source = self.channel_state.lock().unwrap().claimable_htlcs.remove(&payment_hash); if let Some((payment_purpose, mut sources)) = removed_source { assert!(!sources.is_empty()); @@ -3980,8 +3981,12 @@ impl ChannelMana let mut claimable_amt_msat = 0; let mut expected_amt_msat = None; let mut valid_mpp = true; + let mut errs = Vec::new(); + let mut claimed_any_htlcs = false; + let mut channel_state_lock = self.channel_state.lock().unwrap(); + let channel_state = &mut *channel_state_lock; for htlc in sources.iter() { - if let None = channel_state.as_ref().unwrap().short_to_chan_info.get(&htlc.prev_hop.short_channel_id) { + if let None = channel_state.short_to_chan_info.get(&htlc.prev_hop.short_channel_id) { valid_mpp = false; break; } @@ -4014,21 +4019,9 @@ impl ChannelMana expected_amt_msat.unwrap(), claimable_amt_msat); return; } - - let mut errs = Vec::new(); - let mut claimed_any_htlcs = false; - for htlc in sources.drain(..) { - if !valid_mpp { - if channel_state.is_none() { channel_state = Some(self.channel_state.lock().unwrap()); } - let mut htlc_msat_height_data = byte_utils::be64_to_array(htlc.value).to_vec(); - htlc_msat_height_data.extend_from_slice(&byte_utils::be32_to_array( - self.best_block.read().unwrap().height())); - self.fail_htlc_backwards_internal(channel_state.take().unwrap(), - HTLCSource::PreviousHopData(htlc.prev_hop), &payment_hash, - HTLCFailReason::Reason { failure_code: 0x4000|15, data: htlc_msat_height_data }, - HTLCDestination::FailedPayment { payment_hash } ); - } else { - match self.claim_funds_from_hop(channel_state.as_mut().unwrap(), htlc.prev_hop, payment_preimage) { + if valid_mpp { + for htlc in sources.drain(..) { + match self.claim_funds_from_hop(&mut channel_state_lock, htlc.prev_hop, payment_preimage) { ClaimFundsFromHop::MonitorUpdateFail(pk, err, _) => { if let msgs::ErrorAction::IgnoreError = err.err.action { // We got a temporary failure updating monitor, but will claim the @@ -4048,6 +4041,18 @@ impl ChannelMana } } } + mem::drop(channel_state_lock); + if !valid_mpp { + for htlc in sources.drain(..) { + let mut htlc_msat_height_data = byte_utils::be64_to_array(htlc.value).to_vec(); + htlc_msat_height_data.extend_from_slice(&byte_utils::be32_to_array( + self.best_block.read().unwrap().height())); + self.fail_htlc_backwards_internal( + HTLCSource::PreviousHopData(htlc.prev_hop), &payment_hash, + HTLCFailReason::Reason { failure_code: 0x4000|15, data: htlc_msat_height_data }, + HTLCDestination::FailedPayment { payment_hash } ); + } + } if claimed_any_htlcs { self.pending_events.lock().unwrap().push(events::Event::PaymentClaimed { @@ -4057,10 +4062,7 @@ impl ChannelMana }); } - // Now that we've done the entire above loop in one lock, we can handle any errors - // which were generated. - channel_state.take(); - + // Now we can handle any errors which were generated. for (counterparty_node_id, err) in errs.drain(..) { let res: Result<(), _> = Err(err); let _ = handle_error!(self, res, counterparty_node_id); @@ -4307,7 +4309,7 @@ impl ChannelMana self.finalize_claims(finalized_claims); for failure in pending_failures.drain(..) { let receiver = HTLCDestination::NextHopChannel { node_id: Some(counterparty_node_id), channel_id: funding_txo.to_channel_id() }; - self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), failure.0, &failure.1, failure.2, receiver); + self.fail_htlc_backwards_internal(failure.0, &failure.1, failure.2, receiver); } } @@ -4667,7 +4669,7 @@ impl ChannelMana }; for htlc_source in dropped_htlcs.drain(..) { let receiver = HTLCDestination::NextHopChannel { node_id: Some(counterparty_node_id.clone()), channel_id: msg.channel_id }; - self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), htlc_source.0, &htlc_source.1, HTLCFailReason::Reason { failure_code: 0x4000 | 8, data: Vec::new() }, receiver); + self.fail_htlc_backwards_internal(htlc_source.0, &htlc_source.1, HTLCFailReason::Reason { failure_code: 0x4000 | 8, data: Vec::new() }, receiver); } let _ = handle_error!(self, result, *counterparty_node_id); @@ -4869,7 +4871,6 @@ impl ChannelMana for &mut (prev_short_channel_id, prev_funding_outpoint, ref mut pending_forwards) in per_source_pending_forwards { let mut forward_event = None; if !pending_forwards.is_empty() { - let mut channel_state = self.channel_state.lock().unwrap(); let mut forward_htlcs = self.forward_htlcs.lock().unwrap(); if forward_htlcs.is_empty() { forward_event = Some(Duration::from_millis(MIN_HTLC_RELAY_HOLDING_CELL_MILLIS)) @@ -4956,7 +4957,7 @@ impl ChannelMana { for failure in pending_failures.drain(..) { let receiver = HTLCDestination::NextHopChannel { node_id: Some(*counterparty_node_id), channel_id: channel_outpoint.to_channel_id() }; - self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), failure.0, &failure.1, failure.2, receiver); + self.fail_htlc_backwards_internal(failure.0, &failure.1, failure.2, receiver); } self.forward_htlcs(&mut [(short_channel_id, channel_outpoint, pending_forwards)]); self.finalize_claims(finalized_claim_htlcs); @@ -5114,7 +5115,7 @@ impl ChannelMana } else { log_trace!(self.logger, "Failing HTLC with hash {} from our monitor", log_bytes!(htlc_update.payment_hash.0)); let receiver = HTLCDestination::NextHopChannel { node_id: counterparty_node_id, channel_id: funding_outpoint.to_channel_id() }; - self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), htlc_update.source, &htlc_update.payment_hash, HTLCFailReason::Reason { failure_code: 0x4000 | 8, data: Vec::new() }, receiver); + self.fail_htlc_backwards_internal(htlc_update.source, &htlc_update.payment_hash, HTLCFailReason::Reason { failure_code: 0x4000 | 8, data: Vec::new() }, receiver); } }, MonitorEvent::CommitmentTxConfirmed(funding_outpoint) | @@ -5848,7 +5849,7 @@ where self.handle_init_event_channel_failures(failed_channels); for (source, payment_hash, reason, destination) in timed_out_htlcs.drain(..) { - self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), source, &payment_hash, reason, destination); + self.fail_htlc_backwards_internal(source, &payment_hash, reason, destination); } } @@ -7210,7 +7211,7 @@ impl<'a, Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> for htlc_source in failed_htlcs.drain(..) { let (source, payment_hash, counterparty_node_id, channel_id) = htlc_source; let receiver = HTLCDestination::NextHopChannel { node_id: Some(counterparty_node_id), channel_id }; - channel_manager.fail_htlc_backwards_internal(channel_manager.channel_state.lock().unwrap(), source, &payment_hash, HTLCFailReason::Reason { failure_code: 0x4000 | 8, data: Vec::new() }, receiver); + channel_manager.fail_htlc_backwards_internal(source, &payment_hash, HTLCFailReason::Reason { failure_code: 0x4000 | 8, data: Vec::new() }, receiver); } //TODO: Broadcast channel update for closed channels, but only after we've made a -- 2.39.5