fix!: drop nil votes in misbehaviour handling

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 Add an entry to the unreleased section whenever merging a PR to main that is not targeted at a specific release. These entries will eventually be included in a release.
 
+## v2.2.0-provider-lsm
+
 ### Cryptographic verification of equivocation
 * New feature enabling the provider chain to verify equivocation evidence on its own instead of trusting consumer chains, see [EPIC](https://github.com/cosmos/interchain-security/issues/732).
 

tests/integration/misbehaviour.go

@@ -5,6 +5,7 @@ import (
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	ibctmtypes "github.com/cosmos/ibc-go/v4/modules/light-clients/07-tendermint/types"
+	testutil "github.com/cosmos/interchain-security/v2/testutil/crypto"
 	"github.com/cosmos/interchain-security/v2/x/ccv/provider/types"
 	tmtypes "github.com/tendermint/tendermint/types"
 )
@@ -211,6 +212,43 @@ func (s *CCVTestSuite) TestGetByzantineValidators() {
 			[]*tmtypes.Validator{},
 			true,
 		},
+		{
+			"validators who did vote nil should not be returned",
+			func() *ibctmtypes.Misbehaviour {
+				clientHeader := s.consumerChain.CreateTMClientHeader(
+					s.consumerChain.ChainID,
+					int64(clientHeight.RevisionHeight+1),
+					clientHeight,
+					altTime.Add(time.Minute),
+					clientTMValset,
+					clientTMValset,
+					clientTMValset,
+					clientSigners,
+				)
+
+				// create conflicting header with 2/4 validators voting nil
+				clientHeaderWithNilVotes := s.consumerChain.CreateTMClientHeader(
+					s.consumerChain.ChainID,
+					int64(clientHeight.RevisionHeight+1),
+					clientHeight,
+					altTime.Add(time.Hour),
+					clientTMValset,
+					clientTMValset,
+					clientTMValset,
+					clientSigners,
+				)
+				testutil.UpdateHeaderCommitWithNilVotes(clientHeaderWithNilVotes, clientTMValset.Validators[:2])
+
+				return &ibctmtypes.Misbehaviour{
+					ClientId: s.path.EndpointA.ClientID,
+					Header1:  clientHeader,
+					Header2:  clientHeaderWithNilVotes,
+				}
+			},
+			// Expect validators who did NOT vote nil
+			clientTMValset.Validators[2:],
+			true,
+		},
 	}
 
 	for _, tc := range testCases {
@@ -223,21 +261,17 @@ func (s *CCVTestSuite) TestGetByzantineValidators() {
 				s.NoError(err)
 				s.Equal(len(tc.expByzantineValidators), len(byzantineValidators))
 
-				// For both lunatic and equivocation attacks all the validators
-				// who signed the bad header (Header2) should be in returned in the evidence
+				// For both lunatic and equivocation attacks, all the validators
+				// who signed the bad header and didn't vote nil  should be returned
 				if len(tc.expByzantineValidators) > 0 {
-					equivocatingVals := tc.getMisbehaviour().Header2.ValidatorSet
-					s.Equal(len(equivocatingVals.Validators), len(byzantineValidators))
-
-					vs, err := tmtypes.ValidatorSetFromProto(equivocatingVals)
+					expValset := tmtypes.NewValidatorSet(tc.expByzantineValidators)
 					s.NoError(err)
 
 					for _, v := range tc.expByzantineValidators {
-						idx, _ := vs.GetByAddress(v.Address)
+						idx, _ := expValset.GetByAddress(v.Address)
 						s.True(idx >= 0)
 					}
 				}
-
 			} else {
 				s.Error(err)
 			}
@@ -268,25 +302,52 @@ func (s *CCVTestSuite) TestCheckMisbehaviour() {
 	altSigners := make(map[string]tmtypes.PrivValidator, 1)
 	altSigners[clientTMValset.Validators[0].Address.String()] = clientSigners[clientTMValset.Validators[0].Address.String()]
 	altSigners[clientTMValset.Validators[1].Address.String()] = clientSigners[clientTMValset.Validators[1].Address.String()]
+
+	clientHeader := s.consumerChain.CreateTMClientHeader(
+		s.consumerChain.ChainID,
+		int64(clientHeight.RevisionHeight+1),
+		clientHeight,
+		headerTs,
+		clientTMValset,
+		clientTMValset,
+		clientTMValset,
+		clientSigners,
+	)
+
+	// create a conflicting client header with insufficient voting power
+	// by changing 3/4 of its validators votes to nil
+	clientHeaderWithNilVotes := s.consumerChain.CreateTMClientHeader(
+		s.consumerChain.ChainID,
+		int64(clientHeight.RevisionHeight+1),
+		clientHeight,
+		// use a different block time to change the header BlockID
+		headerTs.Add(time.Hour),
+		clientTMValset,
+		clientTMValset,
+		clientTMValset,
+		clientSigners,
+	)
+	testutil.UpdateHeaderCommitWithNilVotes(clientHeaderWithNilVotes, clientTMValset.Validators[:4])
+
 	testCases := []struct {
 		name         string
 		misbehaviour *ibctmtypes.Misbehaviour
 		expPass      bool
 	}{
+		{
+			"identical headers - shouldn't pass",
+			&ibctmtypes.Misbehaviour{
+				ClientId: "clientID",
+				Header1:  clientHeader,
+				Header2:  clientHeader,
+			},
+			false,
+		},
 		{
 			"client state not found - shouldn't pass",
 			&ibctmtypes.Misbehaviour{
 				ClientId: "clientID",
-				Header1: s.consumerChain.CreateTMClientHeader(
-					s.consumerChain.ChainID,
-					int64(clientHeight.RevisionHeight+1),
-					clientHeight,
-					headerTs,
-					clientTMValset,
-					clientTMValset,
-					clientTMValset,
-					clientSigners,
-				),
+				Header1:  clientHeader,
 				Header2: s.consumerChain.CreateTMClientHeader(
 					s.consumerChain.ChainID,
 					int64(clientHeight.RevisionHeight+1),
@@ -321,16 +382,7 @@ func (s *CCVTestSuite) TestCheckMisbehaviour() {
 			"invalid misbehaviour with different header height  - shouldn't pass",
 			&ibctmtypes.Misbehaviour{
 				ClientId: s.path.EndpointA.ClientID,
-				Header1: s.consumerChain.CreateTMClientHeader(
-					s.consumerChain.ChainID,
-					int64(clientHeight.RevisionHeight+1),
-					clientHeight,
-					headerTs,
-					clientTMValset,
-					clientTMValset,
-					clientTMValset,
-					clientSigners,
-				),
+				Header1:  clientHeader,
 				Header2: s.consumerChain.CreateTMClientHeader(
 					s.consumerChain.ChainID,
 					int64(clientHeight.RevisionHeight+2),
@@ -345,49 +397,20 @@ func (s *CCVTestSuite) TestCheckMisbehaviour() {
 			false,
 		},
 		{
-			"valid misbehaviour - should pass",
+			"one header of the misbehaviour has insufficient voting power - shouldn't pass",
 			&ibctmtypes.Misbehaviour{
 				ClientId: s.path.EndpointA.ClientID,
-				Header1: s.consumerChain.CreateTMClientHeader(
-					s.consumerChain.ChainID,
-					int64(clientHeight.RevisionHeight+1),
-					clientHeight,
-					headerTs,
-					clientTMValset,
-					clientTMValset,
-					clientTMValset,
-					clientSigners,
-				),
-				// create header using a different validator set
-				Header2: s.consumerChain.CreateTMClientHeader(
-					s.consumerChain.ChainID,
-					int64(clientHeight.RevisionHeight+1),
-					clientHeight,
-					headerTs,
-					altValset,
-					altValset,
-					clientTMValset,
-					altSigners,
-				),
+				Header1:  clientHeader,
+				Header2:  clientHeaderWithNilVotes,
 			},
-			true,
+			false,
 		},
 		{
-			"valid misbehaviour with already frozen client - should pass",
+			"valid misbehaviour - should pass",
 			&ibctmtypes.Misbehaviour{
 				ClientId: s.path.EndpointA.ClientID,
-				Header1: s.consumerChain.CreateTMClientHeader(
-					s.consumerChain.ChainID,
-					int64(clientHeight.RevisionHeight+1),
-					clientHeight,
-					headerTs,
-					clientTMValset,
-					clientTMValset,
-					clientTMValset,
-					clientSigners,
-				),
-				// the resulting Header2 will have a different BlockID
-				// than Header1 since doesn't share the same valset and signers
+				Header1:  clientHeader,
+				// create header using a different validator set
 				Header2: s.consumerChain.CreateTMClientHeader(
 					s.consumerChain.ChainID,
 					int64(clientHeight.RevisionHeight+1),

testutil/crypto/evidence.go

@@ -1,8 +1,10 @@
 package crypto
 
 import (
+	"fmt"
 	"time"
 
+	ibctmtypes "github.com/cosmos/ibc-go/v4/modules/light-clients/07-tendermint/types"
 	"github.com/tendermint/tendermint/crypto/tmhash"
 	tmtypes "github.com/tendermint/tendermint/types"
 )
@@ -89,3 +91,37 @@ func MakeAndSignVoteWithForgedValAddress(
 	vote.Signature = v.Signature
 	return vote
 }
+
+// UpdateHeaderCommitWithNilVotes updates the given light client header
+// by changing the commit BlockIDFlag of the given validators to nil
+//
+// Note that this method is solely used for testing purpose
+func UpdateHeaderCommitWithNilVotes(header *ibctmtypes.Header, validators []*tmtypes.Validator) {
+	if len(validators) > len(header.ValidatorSet.Validators) {
+		panic(fmt.Sprintf("cannot change more than %d validators votes: got %d",
+			len(header.ValidatorSet.Validators), len(header.ValidatorSet.Validators)))
+	}
+
+	commit, err := tmtypes.CommitFromProto(header.Commit)
+	if err != nil {
+		panic(err)
+	}
+
+	valset, err := tmtypes.ValidatorSetFromProto(header.ValidatorSet)
+	if err != nil {
+		panic(err)
+	}
+
+	for _, v := range validators {
+		// get validator index in valset
+		idx, _ := valset.GetByAddress(v.Address)
+		s := commit.Signatures[idx]
+		// change BlockIDFlag to nil
+		s.BlockIDFlag = tmtypes.BlockIDFlagNil
+		// update the signatures
+		commit.Signatures[idx] = s
+	}
+
+	// update the commit in client the header
+	header.SignedHeader.Commit = commit.ToProto()
+}

x/ccv/provider/keeper/misbehaviour.go

@@ -103,15 +103,15 @@ func (k Keeper) GetByzantineValidators(ctx sdk.Context, misbehaviour ibctmtypes.
 	// create a map with the validators' address that signed header1
 	header1Signers := map[string]struct{}{}
 	for _, sign := range lightBlock1.Commit.Signatures {
-		if sign.Absent() {
+		if !sign.ForBlock() {
 			continue
 		}
 		header1Signers[sign.ValidatorAddress.String()] = struct{}{}
 	}
 
 	// iterate over the header2 signers and check if they signed header1
 	for _, sign := range lightBlock2.Commit.Signatures {
-		if sign.Absent() {
+		if !sign.ForBlock() {
 			continue
 		}
 		if _, ok := header1Signers[sign.ValidatorAddress.String()]; ok {