]> git.bitcoin.ninja Git - rust-lightning/blob - lightning/src/util/enforcing_trait_impls.rs
Merge pull request #1951 from wpaulino/remove-get-node-secret
[rust-lightning] / lightning / src / util / enforcing_trait_impls.rs
1 // This file is Copyright its original authors, visible in version control
2 // history.
3 //
4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
7 // You may not use this file except in accordance with one or both of these
8 // licenses.
9
10 use crate::ln::channel::{ANCHOR_OUTPUT_VALUE_SATOSHI, MIN_CHAN_DUST_LIMIT_SATOSHIS};
11 use crate::ln::chan_utils::{HTLCOutputInCommitment, ChannelPublicKeys, HolderCommitmentTransaction, CommitmentTransaction, ChannelTransactionParameters, TrustedCommitmentTransaction, ClosingTransaction};
12 use crate::ln::{chan_utils, msgs, PaymentPreimage};
13 use crate::chain::keysinterface::{Sign, InMemorySigner, BaseSign};
14
15 use crate::prelude::*;
16 use core::cmp;
17 use crate::sync::{Mutex, Arc};
18 #[cfg(test)] use crate::sync::MutexGuard;
19
20 use bitcoin::blockdata::transaction::{Transaction, EcdsaSighashType};
21 use bitcoin::util::sighash;
22
23 use bitcoin::secp256k1;
24 use bitcoin::secp256k1::{SecretKey, PublicKey};
25 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature};
26 #[cfg(anchors)]
27 use crate::util::events::HTLCDescriptor;
28 use crate::util::ser::{Writeable, Writer};
29 use crate::io::Error;
30
31 /// Initial value for revoked commitment downward counter
32 pub const INITIAL_REVOKED_COMMITMENT_NUMBER: u64 = 1 << 48;
33
34 /// An implementation of Sign that enforces some policy checks.  The current checks
35 /// are an incomplete set.  They include:
36 ///
37 /// - When signing, the holder transaction has not been revoked
38 /// - When revoking, the holder transaction has not been signed
39 /// - The holder commitment number is monotonic and without gaps
40 /// - The revoked holder commitment number is monotonic and without gaps
41 /// - There is at least one unrevoked holder transaction at all times
42 /// - The counterparty commitment number is monotonic and without gaps
43 /// - The pre-derived keys and pre-built transaction in CommitmentTransaction were correctly built
44 ///
45 /// Eventually we will probably want to expose a variant of this which would essentially
46 /// be what you'd want to run on a hardware wallet.
47 ///
48 /// Note that counterparty signatures on the holder transaction are not checked, but it should
49 /// be in a complete implementation.
50 ///
51 /// Note that before we do so we should ensure its serialization format has backwards- and
52 /// forwards-compatibility prefix/suffixes!
53 #[derive(Clone)]
54 pub struct EnforcingSigner {
55         pub inner: InMemorySigner,
56         /// Channel state used for policy enforcement
57         pub state: Arc<Mutex<EnforcementState>>,
58         pub disable_revocation_policy_check: bool,
59 }
60
61 impl EnforcingSigner {
62         /// Construct an EnforcingSigner
63         pub fn new(inner: InMemorySigner) -> Self {
64                 let state = Arc::new(Mutex::new(EnforcementState::new()));
65                 Self {
66                         inner,
67                         state,
68                         disable_revocation_policy_check: false
69                 }
70         }
71
72         /// Construct an EnforcingSigner with externally managed storage
73         ///
74         /// Since there are multiple copies of this struct for each channel, some coordination is needed
75         /// so that all copies are aware of enforcement state.  A pointer to this state is provided
76         /// here, usually by an implementation of KeysInterface.
77         pub fn new_with_revoked(inner: InMemorySigner, state: Arc<Mutex<EnforcementState>>, disable_revocation_policy_check: bool) -> Self {
78                 Self {
79                         inner,
80                         state,
81                         disable_revocation_policy_check
82                 }
83         }
84
85         pub fn opt_anchors(&self) -> bool { self.inner.opt_anchors() }
86
87         #[cfg(test)]
88         pub fn get_enforcement_state(&self) -> MutexGuard<EnforcementState> {
89                 self.state.lock().unwrap()
90         }
91 }
92
93 impl BaseSign for EnforcingSigner {
94         fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
95                 self.inner.get_per_commitment_point(idx, secp_ctx)
96         }
97
98         fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
99                 {
100                         let mut state = self.state.lock().unwrap();
101                         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);
102                         assert!(idx > state.last_holder_commitment, "cannot revoke the last holder commitment - attempted to revoke {} last commitment {}", idx, state.last_holder_commitment);
103                         state.last_holder_revoked_commitment = idx;
104                 }
105                 self.inner.release_commitment_secret(idx)
106         }
107
108         fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction, _preimages: Vec<PaymentPreimage>) -> Result<(), ()> {
109                 let mut state = self.state.lock().unwrap();
110                 let idx = holder_tx.commitment_number();
111                 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);
112                 state.last_holder_commitment = idx;
113                 Ok(())
114         }
115
116         fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
117         fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
118
119         fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
120                 self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
121
122                 {
123                         let mut state = self.state.lock().unwrap();
124                         let actual_commitment_number = commitment_tx.commitment_number();
125                         let last_commitment_number = state.last_counterparty_commitment;
126                         // These commitment numbers are backwards counting.  We expect either the same as the previously encountered,
127                         // or the next one.
128                         assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
129                         // Ensure that the counterparty doesn't get more than two broadcastable commitments -
130                         // the last and the one we are trying to sign
131                         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);
132                         state.last_counterparty_commitment = cmp::min(last_commitment_number, actual_commitment_number)
133                 }
134
135                 Ok(self.inner.sign_counterparty_commitment(commitment_tx, preimages, secp_ctx).unwrap())
136         }
137
138         fn validate_counterparty_revocation(&self, idx: u64, _secret: &SecretKey) -> Result<(), ()> {
139                 let mut state = self.state.lock().unwrap();
140                 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);
141                 state.last_counterparty_revoked_commitment = idx;
142                 Ok(())
143         }
144
145         fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
146                 let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
147                 let commitment_txid = trusted_tx.txid();
148                 let holder_csv = self.inner.counterparty_selected_contest_delay();
149
150                 let state = self.state.lock().unwrap();
151                 let commitment_number = trusted_tx.commitment_number();
152                 if state.last_holder_revoked_commitment - 1 != commitment_number && state.last_holder_revoked_commitment - 2 != commitment_number {
153                         if !self.disable_revocation_policy_check {
154                                 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
155                                        state.last_holder_revoked_commitment, commitment_number, self.inner.commitment_seed[0])
156                         }
157                 }
158
159                 for (this_htlc, sig) in trusted_tx.htlcs().iter().zip(&commitment_tx.counterparty_htlc_sigs) {
160                         assert!(this_htlc.transaction_output_index.is_some());
161                         let keys = trusted_tx.keys();
162                         let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, trusted_tx.feerate_per_kw(), holder_csv, &this_htlc, self.opt_anchors(), false, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
163
164                         let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&this_htlc, self.opt_anchors(), &keys);
165
166                         let sighash_type = if self.opt_anchors() {
167                                 EcdsaSighashType::SinglePlusAnyoneCanPay
168                         } else {
169                                 EcdsaSighashType::All
170                         };
171                         let sighash = hash_to_message!(
172                                 &sighash::SighashCache::new(&htlc_tx).segwit_signature_hash(
173                                         0, &htlc_redeemscript, this_htlc.amount_msat / 1000, sighash_type,
174                                 ).unwrap()[..]
175                         );
176                         secp_ctx.verify_ecdsa(&sighash, sig, &keys.countersignatory_htlc_key).unwrap();
177                 }
178
179                 Ok(self.inner.sign_holder_commitment_and_htlcs(commitment_tx, secp_ctx).unwrap())
180         }
181
182         #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
183         fn unsafe_sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
184                 Ok(self.inner.unsafe_sign_holder_commitment_and_htlcs(commitment_tx, secp_ctx).unwrap())
185         }
186
187         fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
188                 Ok(self.inner.sign_justice_revoked_output(justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap())
189         }
190
191         fn sign_justice_revoked_htlc(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
192                 Ok(self.inner.sign_justice_revoked_htlc(justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
193         }
194
195         #[cfg(anchors)]
196         fn sign_holder_htlc_transaction(
197                 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
198                 secp_ctx: &Secp256k1<secp256k1::All>
199         ) -> Result<Signature, ()> {
200                 let per_commitment_point = self.get_per_commitment_point(htlc_descriptor.per_commitment_number, secp_ctx);
201                 assert_eq!(htlc_tx.input[input], htlc_descriptor.unsigned_tx_input());
202                 assert_eq!(htlc_tx.output[input], htlc_descriptor.tx_output(&per_commitment_point, secp_ctx));
203                 Ok(self.inner.sign_holder_htlc_transaction(htlc_tx, input, htlc_descriptor, secp_ctx).unwrap())
204         }
205
206         fn sign_counterparty_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
207                 Ok(self.inner.sign_counterparty_htlc_transaction(htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
208         }
209
210         fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
211                 closing_tx.verify(self.inner.funding_outpoint().into_bitcoin_outpoint())
212                         .expect("derived different closing transaction");
213                 Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
214         }
215
216         fn sign_holder_anchor_input(
217                 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
218         ) -> Result<Signature, ()> {
219                 debug_assert!(MIN_CHAN_DUST_LIMIT_SATOSHIS > ANCHOR_OUTPUT_VALUE_SATOSHI);
220                 // As long as our minimum dust limit is enforced and is greater than our anchor output
221                 // value, an anchor output can only have an index within [0, 1].
222                 assert!(anchor_tx.input[input].previous_output.vout == 0 || anchor_tx.input[input].previous_output.vout == 1);
223                 self.inner.sign_holder_anchor_input(anchor_tx, input, secp_ctx)
224         }
225
226         fn sign_channel_announcement_with_funding_key(
227                 &self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
228         ) -> Result<Signature, ()> {
229                 self.inner.sign_channel_announcement_with_funding_key(msg, secp_ctx)
230         }
231
232         fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
233                 self.inner.provide_channel_parameters(channel_parameters)
234         }
235 }
236
237 impl Sign for EnforcingSigner {}
238
239 impl Writeable for EnforcingSigner {
240         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
241                 // EnforcingSigner has two fields - `inner` ([`InMemorySigner`]) and `state`
242                 // ([`EnforcementState`]). `inner` is serialized here and deserialized by
243                 // [`SignerProvider::read_chan_signer`]. `state` is managed by [`SignerProvider`]
244                 // and will be serialized as needed by the implementation of that trait.
245                 self.inner.write(writer)?;
246                 Ok(())
247         }
248 }
249
250 impl EnforcingSigner {
251         fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
252                 commitment_tx.verify(&self.inner.get_channel_parameters().as_counterparty_broadcastable(),
253                                      self.inner.counterparty_pubkeys(), self.inner.pubkeys(), secp_ctx)
254                         .expect("derived different per-tx keys or built transaction")
255         }
256
257         fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
258                 commitment_tx.verify(&self.inner.get_channel_parameters().as_holder_broadcastable(),
259                                      self.inner.pubkeys(), self.inner.counterparty_pubkeys(), secp_ctx)
260                         .expect("derived different per-tx keys or built transaction")
261         }
262 }
263
264 /// The state used by [`EnforcingSigner`] in order to enforce policy checks
265 ///
266 /// This structure is maintained by KeysInterface since we may have multiple copies of
267 /// the signer and they must coordinate their state.
268 #[derive(Clone)]
269 pub struct EnforcementState {
270         /// The last counterparty commitment number we signed, backwards counting
271         pub last_counterparty_commitment: u64,
272         /// The last counterparty commitment they revoked, backwards counting
273         pub last_counterparty_revoked_commitment: u64,
274         /// The last holder commitment number we revoked, backwards counting
275         pub last_holder_revoked_commitment: u64,
276         /// The last validated holder commitment number, backwards counting
277         pub last_holder_commitment: u64,
278 }
279
280 impl EnforcementState {
281         /// Enforcement state for a new channel
282         pub fn new() -> Self {
283                 EnforcementState {
284                         last_counterparty_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
285                         last_counterparty_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
286                         last_holder_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
287                         last_holder_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
288                 }
289         }
290 }