grandpa: don't send equivocation reports for local identities (#7372)

* grandpa: don't send equivocation reports for local identities

* grandpa: add test for self-report

* grandpa: fix test compilation

this works on rust nightly but breaks on ci which is using rust stable

client/finality-grandpa/src/environment.rs

@@ -42,8 +42,8 @@ use sp_runtime::traits::{
 use sc_telemetry::{telemetry, CONSENSUS_DEBUG, CONSENSUS_INFO};
 
 use crate::{
-	CommandOrError, Commit, Config, Error, Precommit, Prevote,
-	PrimaryPropose, SignedMessage, NewAuthoritySet, VoterCommand,
+	local_authority_id, CommandOrError, Commit, Config, Error, NewAuthoritySet, Precommit, Prevote,
+	PrimaryPropose, SignedMessage, VoterCommand,
 };
 
 use sp_consensus::SelectChain;
@@ -467,10 +467,18 @@ where
 	/// extrinsic to report the equivocation. In particular, the session membership
 	/// proof must be generated at the block at which the given set was active which
 	/// isn't necessarily the best block if there are pending authority set changes.
-	fn report_equivocation(
+	pub(crate) fn report_equivocation(
 		&self,
 		equivocation: Equivocation<Block::Hash, NumberFor<Block>>,
 	) -> Result<(), Error> {
+		if let Some(local_id) = local_authority_id(&self.voters, self.config.keystore.as_ref()) {
+			if *equivocation.offender() == local_id {
+				return Err(Error::Safety(
+					"Refraining from sending equivocation report for our own equivocation.".into(),
+				));
+			}
+		}
+
 		let is_descendent_of = is_descendent_of(&*self.client, None);
 
 		let best_header = self.select_chain
@@ -724,7 +732,7 @@ where
 		let prevote_timer = Delay::new(self.config.gossip_duration * 2);
 		let precommit_timer = Delay::new(self.config.gossip_duration * 4);
 
-		let local_id = crate::local_authority_id(&self.voters, self.config.keystore.as_ref());
+		let local_id = local_authority_id(&self.voters, self.config.keystore.as_ref());
 
 		let has_voted = match self.voter_set_state.has_voted(round) {
 			HasVoted::Yes(id, vote) => {
@@ -776,7 +784,7 @@ where
 	}
 
 	fn proposed(&self, round: RoundNumber, propose: PrimaryPropose<Block>) -> Result<(), Self::Error> {
-		let local_id = crate::local_authority_id(&self.voters, self.config.keystore.as_ref());
+		let local_id = local_authority_id(&self.voters, self.config.keystore.as_ref());
 
 		let local_id = match local_id {
 			Some(id) => id,
@@ -815,7 +823,7 @@ where
 	}
 
 	fn prevoted(&self, round: RoundNumber, prevote: Prevote<Block>) -> Result<(), Self::Error> {
-		let local_id = crate::local_authority_id(&self.voters, self.config.keystore.as_ref());
+		let local_id = local_authority_id(&self.voters, self.config.keystore.as_ref());
 
 		let local_id = match local_id {
 			Some(id) => id,
@@ -876,7 +884,7 @@ where
 		round: RoundNumber,
 		precommit: Precommit<Block>,
 	) -> Result<(), Self::Error> {
-		let local_id = crate::local_authority_id(&self.voters, self.config.keystore.as_ref());
+		let local_id = local_authority_id(&self.voters, self.config.keystore.as_ref());
 
 		let local_id = match local_id {
 			Some(id) => id,

client/finality-grandpa/src/tests.rs

@@ -1813,3 +1813,49 @@ fn imports_justification_for_regular_blocks_on_import() {
 		client.justification(&BlockId::Hash(block_hash)).unwrap().is_some(),
 	);
 }
+
+#[test]
+fn grandpa_environment_doesnt_send_equivocation_reports_for_itself() {
+	let alice = Ed25519Keyring::Alice;
+	let voters = make_ids(&[alice]);
+
+	let environment = {
+		let mut net = GrandpaTestNet::new(TestApi::new(voters), 1);
+		let peer = net.peer(0);
+		let network_service = peer.network_service().clone();
+		let link = peer.data.lock().take().unwrap();
+		let (keystore, _keystore_path) = create_keystore(alice);
+		test_environment(&link, Some(keystore), network_service.clone(), ())
+	};
+
+	let signed_prevote = {
+		let prevote = finality_grandpa::Prevote {
+			target_hash: H256::random(),
+			target_number: 1,
+		};
+
+		let signed = alice.sign(&[]).into();
+		(prevote, signed)
+	};
+
+	let mut equivocation = finality_grandpa::Equivocation {
+		round_number: 1,
+		identity: alice.public().into(),
+		first: signed_prevote.clone(),
+		second: signed_prevote.clone(),
+	};
+
+	// reporting the equivocation should fail since the offender is a local
+	// authority (i.e. we have keys in our keystore for the given id)
+	let equivocation_proof = sp_finality_grandpa::Equivocation::Prevote(equivocation.clone());
+	assert!(matches!(
+		environment.report_equivocation(equivocation_proof),
+		Err(Error::Safety(_))
+	));
+
+	// if we set the equivocation offender to another id for which we don't have
+	// keys it should work
+	equivocation.identity = Default::default();
+	let equivocation_proof = sp_finality_grandpa::Equivocation::Prevote(equivocation);
+	assert!(environment.report_equivocation(equivocation_proof).is_ok());
+}