X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Futil%2Fenforcing_trait_impls.rs;h=8344f9f357f959b5d62a4e35ee4e1a677ddfa8b4;hb=71739dbe0495b3aed4ce907fea88c122df9ac6a1;hp=f5d531ca320425f7f206a1f476fda5da98e03e4d;hpb=e885d0a7747cfc3b89a3c2765a8c0dd174e3889a;p=rust-lightning diff --git a/lightning/src/util/enforcing_trait_impls.rs b/lightning/src/util/enforcing_trait_impls.rs index f5d531ca..8344f9f3 100644 --- a/lightning/src/util/enforcing_trait_impls.rs +++ b/lightning/src/util/enforcing_trait_impls.rs @@ -7,152 +7,211 @@ // You may not use this file except in accordance with one or both of these // licenses. -use ln::chan_utils::{HTLCOutputInCommitment, ChannelPublicKeys, HolderCommitmentTransaction, CommitmentTransaction, ChannelTransactionParameters, TrustedCommitmentTransaction}; -use ln::{chan_utils, msgs}; -use chain::keysinterface::{ChannelKeys, InMemoryChannelKeys}; +use crate::ln::channel::{ANCHOR_OUTPUT_VALUE_SATOSHI, MIN_CHAN_DUST_LIMIT_SATOSHIS}; +use crate::ln::chan_utils::{HTLCOutputInCommitment, ChannelPublicKeys, HolderCommitmentTransaction, CommitmentTransaction, ChannelTransactionParameters, TrustedCommitmentTransaction, ClosingTransaction}; +use crate::ln::{chan_utils, msgs, PaymentPreimage}; +use crate::chain::keysinterface::{Sign, InMemorySigner, BaseSign}; -use std::cmp; -use std::sync::{Mutex, Arc}; +use crate::prelude::*; +use core::cmp; +use crate::sync::{Mutex, Arc}; +#[cfg(test)] use crate::sync::MutexGuard; -use bitcoin::blockdata::transaction::{Transaction, SigHashType}; -use bitcoin::util::bip143; +use bitcoin::blockdata::transaction::{Transaction, EcdsaSighashType}; +use bitcoin::util::sighash; use bitcoin::secp256k1; -use bitcoin::secp256k1::key::{SecretKey, PublicKey}; -use bitcoin::secp256k1::{Secp256k1, Signature}; -use util::ser::{Writeable, Writer, Readable}; -use std::io::Error; -use ln::msgs::DecodeError; +use bitcoin::secp256k1::{SecretKey, PublicKey}; +use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature}; +use crate::util::ser::{Writeable, Writer}; +use crate::io::Error; /// Initial value for revoked commitment downward counter pub const INITIAL_REVOKED_COMMITMENT_NUMBER: u64 = 1 << 48; -/// An implementation of ChannelKeys that enforces some policy checks. The current checks +/// An implementation of Sign that enforces some policy checks. The current checks /// are an incomplete set. They include: /// /// - When signing, the holder transaction has not been revoked /// - When revoking, the holder transaction has not been signed /// - The holder commitment number is monotonic and without gaps +/// - The revoked holder commitment number is monotonic and without gaps +/// - There is at least one unrevoked holder transaction at all times /// - The counterparty commitment number is monotonic and without gaps /// - The pre-derived keys and pre-built transaction in CommitmentTransaction were correctly built /// /// Eventually we will probably want to expose a variant of this which would essentially /// be what you'd want to run on a hardware wallet. +/// +/// Note that counterparty signatures on the holder transaction are not checked, but it should +/// be in a complete implementation. +/// +/// Note that before we do so we should ensure its serialization format has backwards- and +/// forwards-compatibility prefix/suffixes! #[derive(Clone)] -pub struct EnforcingChannelKeys { - pub inner: InMemoryChannelKeys, - /// The last counterparty commitment number we signed, backwards counting - pub last_commitment_number: Arc>>, - /// The last holder commitment number we revoked, backwards counting - pub revoked_commitment: Arc>, +pub struct EnforcingSigner { + pub inner: InMemorySigner, + /// Channel state used for policy enforcement + pub state: Arc>, pub disable_revocation_policy_check: bool, } -impl EnforcingChannelKeys { - /// Construct an EnforcingChannelKeys - pub fn new(inner: InMemoryChannelKeys) -> Self { +impl EnforcingSigner { + /// Construct an EnforcingSigner + pub fn new(inner: InMemorySigner) -> Self { + let state = Arc::new(Mutex::new(EnforcementState::new())); Self { inner, - last_commitment_number: Arc::new(Mutex::new(None)), - revoked_commitment: Arc::new(Mutex::new(INITIAL_REVOKED_COMMITMENT_NUMBER)), + state, disable_revocation_policy_check: false } } - /// Construct an EnforcingChannelKeys with externally managed storage + /// Construct an EnforcingSigner with externally managed storage /// /// Since there are multiple copies of this struct for each channel, some coordination is needed - /// so that all copies are aware of revocations. A pointer to this state is provided here, usually - /// by an implementation of KeysInterface. - pub fn new_with_revoked(inner: InMemoryChannelKeys, revoked_commitment: Arc>, disable_revocation_policy_check: bool) -> Self { + /// so that all copies are aware of enforcement state. A pointer to this state is provided + /// here, usually by an implementation of KeysInterface. + pub fn new_with_revoked(inner: InMemorySigner, state: Arc>, disable_revocation_policy_check: bool) -> Self { Self { inner, - last_commitment_number: Arc::new(Mutex::new(None)), - revoked_commitment, + state, disable_revocation_policy_check } } + + pub fn opt_anchors(&self) -> bool { self.inner.opt_anchors() } + + #[cfg(test)] + pub fn get_enforcement_state(&self) -> MutexGuard { + self.state.lock().unwrap() + } } -impl ChannelKeys for EnforcingChannelKeys { - fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1) -> PublicKey { +impl BaseSign for EnforcingSigner { + fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1) -> PublicKey { self.inner.get_per_commitment_point(idx, secp_ctx) } fn release_commitment_secret(&self, idx: u64) -> [u8; 32] { { - let mut revoked = self.revoked_commitment.lock().unwrap(); - assert!(idx == *revoked || idx == *revoked - 1, "can only revoke the current or next unrevoked commitment - trying {}, revoked {}", idx, *revoked); - *revoked = idx; + let mut state = self.state.lock().unwrap(); + assert!(idx == state.last_holder_revoked_commitment || idx == state.last_holder_revoked_commitment - 1, "can only revoke the current or next unrevoked commitment - trying {}, last revoked {}", idx, state.last_holder_revoked_commitment); + assert!(idx > state.last_holder_commitment, "cannot revoke the last holder commitment - attempted to revoke {} last commitment {}", idx, state.last_holder_commitment); + state.last_holder_revoked_commitment = idx; } self.inner.release_commitment_secret(idx) } + fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction, _preimages: Vec) -> Result<(), ()> { + let mut state = self.state.lock().unwrap(); + let idx = holder_tx.commitment_number(); + assert!(idx == state.last_holder_commitment || idx == state.last_holder_commitment - 1, "expecting to validate the current or next holder commitment - trying {}, current {}", idx, state.last_holder_commitment); + state.last_holder_commitment = idx; + Ok(()) + } + fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() } fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() } - fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()> { + fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, preimages: Vec, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()> { self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx); { - let mut last_commitment_number_guard = self.last_commitment_number.lock().unwrap(); + let mut state = self.state.lock().unwrap(); let actual_commitment_number = commitment_tx.commitment_number(); - let last_commitment_number = last_commitment_number_guard.unwrap_or(actual_commitment_number); + let last_commitment_number = state.last_counterparty_commitment; // These commitment numbers are backwards counting. We expect either the same as the previously encountered, // or the next one. assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number); - *last_commitment_number_guard = Some(cmp::min(last_commitment_number, actual_commitment_number)) + // Ensure that the counterparty doesn't get more than two broadcastable commitments - + // the last and the one we are trying to sign + assert!(actual_commitment_number >= state.last_counterparty_revoked_commitment - 2, "cannot sign a commitment if second to last wasn't revoked - signing {} revoked {}", actual_commitment_number, state.last_counterparty_revoked_commitment); + state.last_counterparty_commitment = cmp::min(last_commitment_number, actual_commitment_number) } - Ok(self.inner.sign_counterparty_commitment(commitment_tx, secp_ctx).unwrap()) + Ok(self.inner.sign_counterparty_commitment(commitment_tx, preimages, secp_ctx).unwrap()) + } + + fn validate_counterparty_revocation(&self, idx: u64, _secret: &SecretKey) -> Result<(), ()> { + let mut state = self.state.lock().unwrap(); + assert!(idx == state.last_counterparty_revoked_commitment || idx == state.last_counterparty_revoked_commitment - 1, "expecting to validate the current or next counterparty revocation - trying {}, current {}", idx, state.last_counterparty_revoked_commitment); + state.last_counterparty_revoked_commitment = idx; + Ok(()) } - fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()> { + fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()> { let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx); let commitment_txid = trusted_tx.txid(); let holder_csv = self.inner.counterparty_selected_contest_delay(); - let revoked = self.revoked_commitment.lock().unwrap(); + let state = self.state.lock().unwrap(); let commitment_number = trusted_tx.commitment_number(); - if *revoked - 1 != commitment_number && *revoked - 2 != commitment_number { + if state.last_holder_revoked_commitment - 1 != commitment_number && state.last_holder_revoked_commitment - 2 != commitment_number { if !self.disable_revocation_policy_check { panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}", - *revoked, commitment_number, self.inner.commitment_seed[0]) + state.last_holder_revoked_commitment, commitment_number, self.inner.commitment_seed[0]) } } for (this_htlc, sig) in trusted_tx.htlcs().iter().zip(&commitment_tx.counterparty_htlc_sigs) { assert!(this_htlc.transaction_output_index.is_some()); let keys = trusted_tx.keys(); - let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, trusted_tx.feerate_per_kw(), holder_csv, &this_htlc, &keys.broadcaster_delayed_payment_key, &keys.revocation_key); + let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, trusted_tx.feerate_per_kw(), holder_csv, &this_htlc, self.opt_anchors(), &keys.broadcaster_delayed_payment_key, &keys.revocation_key); - let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&this_htlc, &keys); + let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&this_htlc, self.opt_anchors(), &keys); - let sighash = hash_to_message!(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, this_htlc.amount_msat / 1000, SigHashType::All)[..]); - secp_ctx.verify(&sighash, sig, &keys.countersignatory_htlc_key).unwrap(); + let sighash_type = if self.opt_anchors() { + EcdsaSighashType::SinglePlusAnyoneCanPay + } else { + EcdsaSighashType::All + }; + let sighash = hash_to_message!( + &sighash::SighashCache::new(&htlc_tx).segwit_signature_hash( + 0, &htlc_redeemscript, this_htlc.amount_msat / 1000, sighash_type, + ).unwrap()[..] + ); + secp_ctx.verify_ecdsa(&sighash, sig, &keys.countersignatory_htlc_key).unwrap(); } Ok(self.inner.sign_holder_commitment_and_htlcs(commitment_tx, secp_ctx).unwrap()) } #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))] - fn unsafe_sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()> { + fn unsafe_sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()> { Ok(self.inner.unsafe_sign_holder_commitment_and_htlcs(commitment_tx, secp_ctx).unwrap()) } - fn sign_justice_transaction(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &Option, secp_ctx: &Secp256k1) -> Result { - Ok(self.inner.sign_justice_transaction(justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap()) + fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1) -> Result { + Ok(self.inner.sign_justice_revoked_output(justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap()) + } + + fn sign_justice_revoked_htlc(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1) -> Result { + Ok(self.inner.sign_justice_revoked_htlc(justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap()) } - fn sign_counterparty_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1) -> Result { + fn sign_counterparty_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1) -> Result { Ok(self.inner.sign_counterparty_htlc_transaction(htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap()) } - fn sign_closing_transaction(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1) -> Result { + fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1) -> Result { + closing_tx.verify(self.inner.funding_outpoint().into_bitcoin_outpoint()) + .expect("derived different closing transaction"); Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap()) } - fn sign_channel_announcement(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1) -> Result { + fn sign_holder_anchor_input( + &self, anchor_tx: &mut Transaction, input: usize, secp_ctx: &Secp256k1, + ) -> Result { + debug_assert!(MIN_CHAN_DUST_LIMIT_SATOSHIS > ANCHOR_OUTPUT_VALUE_SATOSHI); + // As long as our minimum dust limit is enforced and is greater than our anchor output + // value, an anchor output can only have an index within [0, 1]. + assert!(anchor_tx.input[input].previous_output.vout == 0 || anchor_tx.input[input].previous_output.vout == 1); + self.inner.sign_holder_anchor_input(anchor_tx, input, secp_ctx) + } + + fn sign_channel_announcement(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1) + -> Result<(Signature, Signature), ()> { self.inner.sign_channel_announcement(msg, secp_ctx) } @@ -161,30 +220,20 @@ impl ChannelKeys for EnforcingChannelKeys { } } +impl Sign for EnforcingSigner {} -impl Writeable for EnforcingChannelKeys { +impl Writeable for EnforcingSigner { fn write(&self, writer: &mut W) -> Result<(), Error> { + // EnforcingSigner has two fields - `inner` ([`InMemorySigner`]) and `state` + // ([`EnforcementState`]). `inner` is serialized here and deserialized by + // [`KeysInterface::read_chan_signer`]. `state` is managed by [`KeysInterface`] + // and will be serialized as needed by the implementation of that trait. self.inner.write(writer)?; - let last = *self.last_commitment_number.lock().unwrap(); - last.write(writer)?; Ok(()) } } -impl Readable for EnforcingChannelKeys { - fn read(reader: &mut R) -> Result { - let inner = Readable::read(reader)?; - let last_commitment_number = Readable::read(reader)?; - Ok(EnforcingChannelKeys { - inner, - last_commitment_number: Arc::new(Mutex::new(last_commitment_number)), - revoked_commitment: Arc::new(Mutex::new(INITIAL_REVOKED_COMMITMENT_NUMBER)), - disable_revocation_policy_check: false, - }) - } -} - -impl EnforcingChannelKeys { +impl EnforcingSigner { fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1) -> TrustedCommitmentTransaction<'a> { commitment_tx.verify(&self.inner.get_channel_parameters().as_counterparty_broadcastable(), self.inner.counterparty_pubkeys(), self.inner.pubkeys(), secp_ctx) @@ -197,3 +246,31 @@ impl EnforcingChannelKeys { .expect("derived different per-tx keys or built transaction") } } + +/// The state used by [`EnforcingSigner`] in order to enforce policy checks +/// +/// This structure is maintained by KeysInterface since we may have multiple copies of +/// the signer and they must coordinate their state. +#[derive(Clone)] +pub struct EnforcementState { + /// The last counterparty commitment number we signed, backwards counting + pub last_counterparty_commitment: u64, + /// The last counterparty commitment they revoked, backwards counting + pub last_counterparty_revoked_commitment: u64, + /// The last holder commitment number we revoked, backwards counting + pub last_holder_revoked_commitment: u64, + /// The last validated holder commitment number, backwards counting + pub last_holder_commitment: u64, +} + +impl EnforcementState { + /// Enforcement state for a new channel + pub fn new() -> Self { + EnforcementState { + last_counterparty_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER, + last_counterparty_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER, + last_holder_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER, + last_holder_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER, + } + } +}