[BEEFY] Add runtime support for reporting fork voting (paritytech#4522)

Related to paritytech#4523

Extracting part of paritytech#1903
(credits to @Lederstrumpf for the high-level strategy), but also
introducing significant adjustments both to the approach and to the
code. The main adjustment is the fact that the `ForkVotingProof` accepts
only one vote, compared to the original version which accepted a
`vec![]`. With this approach more calls are needed in order to report
multiple equivocated votes on the same commit, but it simplifies a lot
the checking logic. We can add support for reporting multiple signatures
at once in the future.

There are 2 things that are missing in order to consider this issue
done, but I would propose to do them in a separate PR since this one is
already pretty big:
- benchmarks/computing a weight for the new extrinsic (this wasn't
present in paritytech#1903 either)
- exposing an API for generating the ancestry proof. I'm not sure if we
should do this in the Mmr pallet or in the Beefy pallet

Co-authored-by: Robert Hambrock <roberthambrock@gmail.com>

---------

Co-authored-by: Adrian Catangiu <adrian@parity.io>

polkadot/node/service/src/fake_runtime_api.rs

@@ -241,7 +241,7 @@ sp_api::impl_runtime_apis! {
  unimplemented!()
  }
 
- fn submit_report_equivocation_unsigned_extrinsic(
+ fn submit_report_double_voting_unsigned_extrinsic(
  _: sp_consensus_beefy::DoubleVotingProof<
  BlockNumber,
  BeefyId,

polkadot/runtime/rococo/src/lib.rs

@@ -1283,6 +1283,7 @@ impl pallet_beefy::Config for Runtime {
  type MaxNominators = ConstU32<0>;
  type MaxSetIdSessionEntries = BeefySetIdSessionEntries;
  type OnNewValidatorSet = MmrLeaf;
+ type AncestryHelper = MmrLeaf;
  type WeightInfo = ();
  type KeyOwnerProof = <Historical as KeyOwnerProofSystem<(KeyTypeId, BeefyId)>>::Proof;
  type EquivocationReportSystem =
@@ -2052,7 +2053,7 @@ sp_api::impl_runtime_apis! {
  }
  }
 
- #[api_version(3)]
+ #[api_version(4)]
  impl sp_consensus_beefy::BeefyApi<Block, BeefyId> for Runtime {
  fn beefy_genesis() -> Option<BlockNumber> {
  pallet_beefy::GenesisBlock::<Runtime>::get()
@@ -2062,7 +2063,7 @@ sp_api::impl_runtime_apis! {
  Beefy::validator_set()
  }
 
- fn submit_report_equivocation_unsigned_extrinsic(
+ fn submit_report_double_voting_unsigned_extrinsic(
  equivocation_proof: sp_consensus_beefy::DoubleVotingProof<
  BlockNumber,
  BeefyId,
@@ -2072,7 +2073,7 @@ sp_api::impl_runtime_apis! {
  ) -> Option<()> {
  let key_owner_proof = key_owner_proof.decode()?;
 
- Beefy::submit_unsigned_equivocation_report(
+ Beefy::submit_unsigned_double_voting_report(
  equivocation_proof,
  key_owner_proof,
  )

polkadot/runtime/test-runtime/src/lib.rs

@@ -1015,7 +1015,7 @@ sp_api::impl_runtime_apis! {
  None
  }
 
- fn submit_report_equivocation_unsigned_extrinsic(
+ fn submit_report_double_voting_unsigned_extrinsic(
  _equivocation_proof: sp_consensus_beefy::DoubleVotingProof<
  BlockNumber,
  BeefyId,

polkadot/runtime/westend/src/lib.rs

@@ -328,6 +328,7 @@ impl pallet_beefy::Config for Runtime {
  type MaxNominators = MaxNominators;
  type MaxSetIdSessionEntries = BeefySetIdSessionEntries;
  type OnNewValidatorSet = BeefyMmrLeaf;
+ type AncestryHelper = BeefyMmrLeaf;
  type WeightInfo = ();
  type KeyOwnerProof = sp_session::MembershipProof;
  type EquivocationReportSystem =
@@ -2009,6 +2010,7 @@ sp_api::impl_runtime_apis! {
  }
  }
 
+ #[api_version(4)]
  impl sp_consensus_beefy::BeefyApi<Block, BeefyId> for Runtime {
  fn beefy_genesis() -> Option<BlockNumber> {
  pallet_beefy::GenesisBlock::<Runtime>::get()
@@ -2018,7 +2020,7 @@ sp_api::impl_runtime_apis! {
  Beefy::validator_set()
  }
 
- fn submit_report_equivocation_unsigned_extrinsic(
+ fn submit_report_double_voting_unsigned_extrinsic(
  equivocation_proof: sp_consensus_beefy::DoubleVotingProof<
  BlockNumber,
  BeefyId,
@@ -2028,7 +2030,7 @@ sp_api::impl_runtime_apis! {
  ) -> Option<()> {
  let key_owner_proof = key_owner_proof.decode()?;
 
- Beefy::submit_unsigned_equivocation_report(
+ Beefy::submit_unsigned_double_voting_report(
  equivocation_proof,
  key_owner_proof,
  )

prdoc/pr_4522.prdoc

@@ -0,0 +1,39 @@
+# Schema: Polkadot SDK PRDoc Schema (prdoc) v1.0.0
+# See doc at https://raw.githubusercontent.com/paritytech/polkadot-sdk/master/prdoc/schema_user.json
+
+title: Added runtime support for reporting BEEFY fork voting
+
+doc:
+ - audience:
+ - Runtime Dev
+ - Runtime User
+ description: |
+ This PR adds the `report_fork_voting`, `report_future_voting` extrinsics to `pallet-beefy`
+ and renames the `report_equivocation` extrinsic to `report_double_voting`.
+ `report_fork_voting` can't be called yet, since it uses `Weight::MAX` weight. We will
+ add benchmarks for it and set the proper weight in a future PR.
+ Also a new `AncestryHelper` associated trait was added to `pallet_beefy::Config`.
+ - audience: Node Dev
+ description: |
+ This PR renames the `submit_report_equivocation_unsigned_extrinsic` in `BeefyApi` to
+ `submit_report_double_voting_unsigned_extrinsic`and bumps the `BeefyApi` version from 3 to 4.
+
+crates: 
+ - name: pallet-beefy
+ bump: major
+ - name: pallet-beefy-mmr
+ bump: minor
+ - name: pallet-mmr
+ bump: major
+ - name: sc-consensus-beefy
+ bump: patch
+ - name: kitchensink-runtime
+ bump: major
+ - name: rococo-runtime
+ bump: major
+ - name: westend-runtime
+ bump: major
+ - name: sp-consensus-beefy
+ bump: major
+ - name: polkadot-service
+ bump: patch

substrate/bin/node/runtime/src/lib.rs

@@ -2548,6 +2548,7 @@ impl pallet_beefy::Config for Runtime {
  type MaxNominators = ConstU32<0>;
  type MaxSetIdSessionEntries = BeefySetIdSessionEntries;
  type OnNewValidatorSet = MmrLeaf;
+ type AncestryHelper = MmrLeaf;
  type WeightInfo = ();
  type KeyOwnerProof = <Historical as KeyOwnerProofSystem<(KeyTypeId, BeefyId)>>::Proof;
  type EquivocationReportSystem =
@@ -3032,7 +3033,7 @@ impl_runtime_apis! {
  }
  }
 
- #[api_version(3)]
+ #[api_version(4)]
  impl sp_consensus_beefy::BeefyApi<Block, BeefyId> for Runtime {
  fn beefy_genesis() -> Option<BlockNumber> {
  pallet_beefy::GenesisBlock::<Runtime>::get()
@@ -3042,7 +3043,7 @@ impl_runtime_apis! {
  Beefy::validator_set()
  }
 
- fn submit_report_equivocation_unsigned_extrinsic(
+ fn submit_report_double_voting_unsigned_extrinsic(
  equivocation_proof: sp_consensus_beefy::DoubleVotingProof<
  BlockNumber,
  BeefyId,
@@ -3052,7 +3053,7 @@ impl_runtime_apis! {
  ) -> Option<()> {
  let key_owner_proof = key_owner_proof.decode()?;
 
- Beefy::submit_unsigned_equivocation_report(
+ Beefy::submit_unsigned_double_voting_report(
  equivocation_proof,
  key_owner_proof,
  )

substrate/client/consensus/beefy/src/fisherman.rs

@@ -23,7 +23,7 @@ use sp_api::ProvideRuntimeApi;
 use sp_application_crypto::RuntimeAppPublic;
 use sp_blockchain::HeaderBackend;
 use sp_consensus_beefy::{
- check_equivocation_proof, AuthorityIdBound, BeefyApi, BeefySignatureHasher, DoubleVotingProof,
+ check_double_voting_proof, AuthorityIdBound, BeefyApi, BeefySignatureHasher, DoubleVotingProof,
  OpaqueKeyOwnershipProof, ValidatorSetId,
 };
 use sp_runtime::{
@@ -132,7 +132,7 @@ where
  (active_rounds.validators(), active_rounds.validator_set_id());
  let offender_id = proof.offender_id();
 
- if !check_equivocation_proof::<_, _, BeefySignatureHasher>(&proof) {
+ if !check_double_voting_proof::<_, _, BeefySignatureHasher>(&proof) {
  debug!(target: LOG_TARGET, "🥩 Skipping report for bad equivocation {:?}", proof);
  return Ok(());
  }
@@ -155,7 +155,7 @@ where
  for ProvedValidator { key_owner_proof, .. } in key_owner_proofs {
  self.runtime
  .runtime_api()
- .submit_report_equivocation_unsigned_extrinsic(
+ .submit_report_double_voting_unsigned_extrinsic(
  best_block_hash,
  proof.clone(),
  key_owner_proof,

substrate/client/consensus/beefy/src/tests.rs

@@ -314,7 +314,7 @@ sp_api::mock_impl_runtime_apis! {
  self.inner.validator_set.clone()
  }
 
- fn submit_report_equivocation_unsigned_extrinsic(
+ fn submit_report_double_voting_unsigned_extrinsic(
  proof: DoubleVotingProof<NumberFor<Block>, AuthorityId, Signature>,
  _dummy: OpaqueKeyOwnershipProof,
  ) -> Option<()> {

substrate/client/consensus/beefy/src/worker.rs

@@ -1039,7 +1039,7 @@ pub(crate) mod tests {
  ecdsa_crypto, known_payloads,
  known_payloads::MMR_ROOT_ID,
  mmr::MmrRootProvider,
- test_utils::{generate_equivocation_proof, Keyring},
+ test_utils::{generate_double_voting_proof, Keyring},
  ConsensusLog, Payload, SignedCommitment,
  };
  use sp_runtime::traits::{Header as HeaderT, One};
@@ -1586,7 +1586,7 @@ pub(crate) mod tests {
  let payload2 = Payload::from_single_entry(MMR_ROOT_ID, vec![128]);
 
  // generate an equivocation proof, with Bob as perpetrator
- let good_proof = generate_equivocation_proof(
+ let good_proof = generate_double_voting_proof(
  (block_num, payload1.clone(), set_id, &Keyring::Bob),
  (block_num, payload2.clone(), set_id, &Keyring::Bob),
  );
@@ -1618,7 +1618,7 @@ pub(crate) mod tests {
  assert!(api_alice.reported_equivocations.as_ref().unwrap().lock().is_empty());
 
  // now let's try reporting a self-equivocation
- let self_proof = generate_equivocation_proof(
+ let self_proof = generate_double_voting_proof(
  (block_num, payload1.clone(), set_id, &Keyring::Alice),
  (block_num, payload2.clone(), set_id, &Keyring::Alice),
  );

substrate/frame/beefy-mmr/src/lib.rs

@@ -33,20 +33,22 @@
 //!
 //! and thanks to versioning can be easily updated in the future.
 
-use sp_runtime::traits::{Convert, Member};
+use sp_runtime::traits::{Convert, Header, Member};
 use sp_std::prelude::*;
 
 use codec::Decode;
-use pallet_mmr::{LeafDataProvider, ParentNumberAndHash};
+use pallet_mmr::{primitives::AncestryProof, LeafDataProvider, ParentNumberAndHash};
 use sp_consensus_beefy::{
+ known_payloads,
  mmr::{BeefyAuthoritySet, BeefyDataProvider, BeefyNextAuthoritySet, MmrLeaf, MmrLeafVersion},
- ValidatorSet as BeefyValidatorSet,
+ AncestryHelper, Commitment, ConsensusLog, ValidatorSet as BeefyValidatorSet,
 };
 
 use frame_support::{crypto::ecdsa::ECDSAExt, traits::Get};
-use frame_system::pallet_prelude::BlockNumberFor;
+use frame_system::pallet_prelude::{BlockNumberFor, HeaderFor};
 
 pub use pallet::*;
+use sp_runtime::generic::OpaqueDigestItemId;
 
 #[cfg(test)]
 mod mock;
@@ -172,6 +174,75 @@ where
  }
 }
 
+impl<T: Config> AncestryHelper<HeaderFor<T>> for Pallet<T>
+where
+ T: pallet_mmr::Config<Hashing = sp_consensus_beefy::MmrHashing>,
+{
+ type Proof = AncestryProof<MerkleRootOf<T>>;
+ type ValidationContext = MerkleRootOf<T>;
+
+ fn extract_validation_context(header: HeaderFor<T>) -> Option<Self::ValidationContext> {
+ // Check if the provided header is canonical.
+ let expected_hash = frame_system::Pallet::<T>::block_hash(header.number());
+ if expected_hash != header.hash() {
+ return None;
+ }
+
+ // Extract the MMR root from the header digest
+ header.digest().convert_first(|l| {
+ l.try_to(OpaqueDigestItemId::Consensus(&sp_consensus_beefy::BEEFY_ENGINE_ID))
+ .and_then(|log: ConsensusLog<<T as pallet_beefy::Config>::BeefyId>| match log {
+ ConsensusLog::MmrRoot(mmr_root) => Some(mmr_root),
+ _ => None,
+ })
+ })
+ }
+
+ fn is_non_canonical(
+ commitment: &Commitment<BlockNumberFor<T>>,
+ proof: Self::Proof,
+ context: Self::ValidationContext,
+ ) -> bool {
+ let commitment_leaf_count =
+ match pallet_mmr::Pallet::<T>::block_num_to_leaf_count(commitment.block_number) {
+ Ok(commitment_leaf_count) => commitment_leaf_count,
+ Err(_) => {
+ // We can't prove that the commitment is non-canonical if the
+ // `commitment.block_number` is invalid.
+ return false
+ },
+ };
+ if commitment_leaf_count != proof.prev_leaf_count {
+ // Can't prove that the commitment is non-canonical if the `commitment.block_number`
+ // doesn't match the ancestry proof.
+ return false;
+ }
+
+ let canonical_mmr_root = context;
+ let canonical_prev_root =
+ match pallet_mmr::Pallet::<T>::verify_ancestry_proof(canonical_mmr_root, proof) {
+ Ok(canonical_prev_root) => canonical_prev_root,
+ Err(_) => {
+ // Can't prove that the commitment is non-canonical if the proof
+ // is invalid.
+ return false
+ },
+ };
+
+ let commitment_root =
+ match commitment.payload.get_decoded::<MerkleRootOf<T>>(&known_payloads::MMR_ROOT_ID) {
+ Some(commitment_root) => commitment_root,
+ None => {
+ // If the commitment doesn't contain any MMR root, while the proof is valid,
+ // the commitment is invalid
+ return true
+ },
+ };
+
+ canonical_prev_root != commitment_root
+ }
+}
+
 impl<T: Config> Pallet<T> {
  /// Return the currently active BEEFY authority set proof.
  pub fn authority_set_proof() -> BeefyAuthoritySet<MerkleRootOf<T>> {

substrate/frame/beefy-mmr/src/mock.rs

@@ -101,6 +101,7 @@ impl pallet_beefy::Config for Test {
  type MaxNominators = ConstU32<1000>;
  type MaxSetIdSessionEntries = ConstU64<100>;
  type OnNewValidatorSet = BeefyMmr;
+ type AncestryHelper = BeefyMmr;
  type WeightInfo = ();
  type KeyOwnerProof = sp_core::Void;
  type EquivocationReportSystem = ();