From 710954f88bc39d58713e982caaad05f4c61d92ed Mon Sep 17 00:00:00 2001 From: Valentine Wallace Date: Fri, 4 Feb 2022 15:21:01 -0500 Subject: [PATCH] Don't send channel updates for private chans on error This commit also adds additional checks for the second-to-last (phantom) hop for phantom payments. --- lightning/src/ln/channelmanager.rs | 72 ++++++++++++++++-------------- 1 file changed, 39 insertions(+), 33 deletions(-) diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs index caa5fba03..0a0407eac 100644 --- a/lightning/src/ln/channelmanager.rs +++ b/lightning/src/ln/channelmanager.rs @@ -2293,53 +2293,59 @@ impl ChannelMana if let &PendingHTLCRouting::Forward { ref short_channel_id, .. } = routing { let id_option = channel_state.as_ref().unwrap().short_to_id.get(&short_channel_id).cloned(); if let Some((err, code, chan_update)) = loop { - let forwarding_id = match id_option { + let forwarding_id_opt = match id_option { None => { // unknown_next_peer // Note that this is likely a timing oracle for detecting whether an scid is a // phantom. if fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, *short_channel_id) { - break None + None + } else { + break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None)); } - break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None)); }, - Some(id) => id.clone(), + Some(id) => Some(id.clone()), }; + let (chan_update_opt, forwardee_cltv_expiry_delta) = if let Some(forwarding_id) = forwarding_id_opt { + let chan = channel_state.as_mut().unwrap().by_id.get_mut(&forwarding_id).unwrap(); + // Leave channel updates as None for private channels. + let chan_update_opt = if chan.should_announce() { + Some(self.get_channel_update_for_unicast(chan).unwrap()) } else { None }; + if !chan.should_announce() && !self.default_configuration.accept_forwards_to_priv_channels { + // Note that the behavior here should be identical to the above block - we + // should NOT reveal the existence or non-existence of a private channel if + // we don't allow forwards outbound over them. + break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None)); + } - let chan = channel_state.as_mut().unwrap().by_id.get_mut(&forwarding_id).unwrap(); - - if !chan.should_announce() && !self.default_configuration.accept_forwards_to_priv_channels { - // Note that the behavior here should be identical to the above block - we - // should NOT reveal the existence or non-existence of a private channel if - // we don't allow forwards outbound over them. - break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None)); - } + // Note that we could technically not return an error yet here and just hope + // that the connection is reestablished or monitor updated by the time we get + // around to doing the actual forward, but better to fail early if we can and + // hopefully an attacker trying to path-trace payments cannot make this occur + // on a small/per-node/per-channel scale. + if !chan.is_live() { // channel_disabled + break Some(("Forwarding channel is not in a ready state.", 0x1000 | 20, chan_update_opt)); + } + if *amt_to_forward < chan.get_counterparty_htlc_minimum_msat() { // amount_below_minimum + break Some(("HTLC amount was below the htlc_minimum_msat", 0x1000 | 11, chan_update_opt)); + } + let fee = amt_to_forward.checked_mul(chan.get_fee_proportional_millionths() as u64) + .and_then(|prop_fee| { (prop_fee / 1000000) + .checked_add(chan.get_outbound_forwarding_fee_base_msat() as u64) }); + if fee.is_none() || msg.amount_msat < fee.unwrap() || (msg.amount_msat - fee.unwrap()) < *amt_to_forward { // fee_insufficient + break Some(("Prior hop has deviated from specified fees parameters or origin node has obsolete ones", 0x1000 | 12, chan_update_opt)); + } + (chan_update_opt, chan.get_cltv_expiry_delta()) + } else { (None, MIN_CLTV_EXPIRY_DELTA) }; - // Note that we could technically not return an error yet here and just hope - // that the connection is reestablished or monitor updated by the time we get - // around to doing the actual forward, but better to fail early if we can and - // hopefully an attacker trying to path-trace payments cannot make this occur - // on a small/per-node/per-channel scale. - if !chan.is_live() { // channel_disabled - break Some(("Forwarding channel is not in a ready state.", 0x1000 | 20, Some(self.get_channel_update_for_unicast(chan).unwrap()))); - } - if *amt_to_forward < chan.get_counterparty_htlc_minimum_msat() { // amount_below_minimum - break Some(("HTLC amount was below the htlc_minimum_msat", 0x1000 | 11, Some(self.get_channel_update_for_unicast(chan).unwrap()))); - } - let fee = amt_to_forward.checked_mul(chan.get_fee_proportional_millionths() as u64) - .and_then(|prop_fee| { (prop_fee / 1000000) - .checked_add(chan.get_outbound_forwarding_fee_base_msat() as u64) }); - if fee.is_none() || msg.amount_msat < fee.unwrap() || (msg.amount_msat - fee.unwrap()) < *amt_to_forward { // fee_insufficient - break Some(("Prior hop has deviated from specified fees parameters or origin node has obsolete ones", 0x1000 | 12, Some(self.get_channel_update_for_unicast(chan).unwrap()))); - } - if (msg.cltv_expiry as u64) < (*outgoing_cltv_value) as u64 + chan.get_cltv_expiry_delta() as u64 { // incorrect_cltv_expiry - break Some(("Forwarding node has tampered with the intended HTLC values or origin node has an obsolete cltv_expiry_delta", 0x1000 | 13, Some(self.get_channel_update_for_unicast(chan).unwrap()))); + if (msg.cltv_expiry as u64) < (*outgoing_cltv_value) as u64 + forwardee_cltv_expiry_delta as u64 { // incorrect_cltv_expiry + break Some(("Forwarding node has tampered with the intended HTLC values or origin node has an obsolete cltv_expiry_delta", 0x1000 | 13, chan_update_opt)); } let cur_height = self.best_block.read().unwrap().height() + 1; // Theoretically, channel counterparty shouldn't send us a HTLC expiring now, // but we want to be robust wrt to counterparty packet sanitization (see // HTLC_FAIL_BACK_BUFFER rationale). if msg.cltv_expiry <= cur_height + HTLC_FAIL_BACK_BUFFER as u32 { // expiry_too_soon - break Some(("CLTV expiry is too close", 0x1000 | 14, Some(self.get_channel_update_for_unicast(chan).unwrap()))); + break Some(("CLTV expiry is too close", 0x1000 | 14, chan_update_opt)); } if msg.cltv_expiry > cur_height + CLTV_FAR_FAR_AWAY as u32 { // expiry_too_far break Some(("CLTV expiry is too far in the future", 21, None)); @@ -2353,7 +2359,7 @@ impl ChannelMana // but there is no need to do that, and since we're a bit conservative with our // risk threshold it just results in failing to forward payments. if (*outgoing_cltv_value) as u64 <= (cur_height + LATENCY_GRACE_PERIOD_BLOCKS) as u64 { - break Some(("Outgoing CLTV value is too soon", 0x1000 | 14, Some(self.get_channel_update_for_unicast(chan).unwrap()))); + break Some(("Outgoing CLTV value is too soon", 0x1000 | 14, chan_update_opt)); } break None; -- 2.39.5