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Don't send channel updates for private chans on error

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This commit also adds additional checks for the second-to-last (phantom) hop for phantom payments.
This commit is contained in:
Valentine Wallace 2022-02-04 15:21:01 -05:00
parent c417a51b65
commit 710954f88b
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1 changed files with 39 additions and 33 deletions
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72
lightning/src/ln/channelmanager.rs
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@ -2293,53 +2293,59 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> 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();
// 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) };
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, 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<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> 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;