check attestation signature (#10018)

cl/beacon/synced_data/interface.go

@@ -6,6 +6,7 @@ import "github.com/ledgerwatch/erigon/cl/phase1/core/state"
 type SyncedData interface {
 	OnHeadState(newState *state.CachingBeaconState) (err error)
 	HeadState() *state.CachingBeaconState
+	HeadStateReader() state.BeaconStateReader
 	Syncing() bool
 	HeadSlot() uint64
 }

cl/beacon/synced_data/synced_data.go

@@ -43,6 +43,14 @@ func (s *SyncedDataManager) HeadState() *state.CachingBeaconState {
 	return nil
 }
 
+func (s *SyncedDataManager) HeadStateReader() state.BeaconStateReader {
+	headstate := s.HeadState()
+	if headstate == nil {
+		return nil
+	}
+	return headstate
+}
+
 func (s *SyncedDataManager) Syncing() bool {
 	if !s.enabled {
 		return false

cl/phase1/core/state/interface.go

@@ -0,0 +1,12 @@
+package state
+
+import libcommon "github.com/ledgerwatch/erigon-lib/common"
+
+// BeaconStateReader is an interface for reading the beacon state.
+//
+//go:generate mockgen -destination=./mock_services/beacon_state_reader.go -package=mock_services . BeaconStateReader
+type BeaconStateReader interface {
+	ValidatorPublicKey(index int) (libcommon.Bytes48, error)
+	GetDomain(domainType [4]byte, epoch uint64) ([]byte, error)
+	CommitteeCount(epoch uint64) uint64
+}

cl/phase1/network/services/attestation_service.go

@@ -5,9 +5,11 @@ import (
 	"fmt"
 	"time"
 
+	"github.com/Giulio2002/bls"
 	"github.com/ledgerwatch/erigon/cl/beacon/synced_data"
 	"github.com/ledgerwatch/erigon/cl/clparams"
 	"github.com/ledgerwatch/erigon/cl/cltypes/solid"
+	"github.com/ledgerwatch/erigon/cl/fork"
 	"github.com/ledgerwatch/erigon/cl/phase1/core/state/lru"
 	"github.com/ledgerwatch/erigon/cl/phase1/forkchoice"
 	"github.com/ledgerwatch/erigon/cl/phase1/network/subnets"
@@ -19,6 +21,8 @@ import (
 var (
 	computeSubnetForAttestation  = subnets.ComputeSubnetForAttestation
 	computeCommitteeCountPerSlot = subnets.ComputeCommitteeCountPerSlot
+	computeSigningRoot           = fork.ComputeSigningRoot
+	blsVerify                    = bls.Verify
 )
 
 type attestationService struct {
@@ -59,7 +63,7 @@ func (s *attestationService) ProcessMessage(ctx context.Context, subnet *uint64,
 		committeeIndex = att.AttestantionData().CommitteeIndex()
 		targetEpoch    = att.AttestantionData().Target().Epoch()
 	)
-	headState := s.syncedDataManager.HeadState()
+	headState := s.syncedDataManager.HeadStateReader()
 	if headState == nil {
 		return ErrIgnore
 	}
@@ -117,7 +121,6 @@ func (s *attestationService) ProcessMessage(ctx context.Context, subnet *uint64,
 	if setBits != 1 {
 		return fmt.Errorf("attestation does not have exactly one participating validator")
 	}
-
 	// [IGNORE] There has been no other valid attestation seen on an attestation subnet that has an identical attestation.data.target.epoch and participating validator index.
 	if err != nil {
 		return err
@@ -133,6 +136,26 @@ func (s *attestationService) ProcessMessage(ctx context.Context, subnet *uint64,
 	}
 	s.validatorAttestationSeen.Add(vIndex, targetEpoch)
 
+	// [REJECT] The signature of attestation is valid.
+	signature := att.Signature()
+	pubKey, err := headState.ValidatorPublicKey(int(beaconCommittee[onBitIndex]))
+	if err != nil {
+		return fmt.Errorf("unable to get public key: %v", err)
+	}
+	domain, err := headState.GetDomain(s.beaconCfg.DomainBeaconAttester, targetEpoch)
+	if err != nil {
+		return fmt.Errorf("unable to get the domain: %v", err)
+	}
+	signingRoot, err := computeSigningRoot(att.AttestantionData(), domain)
+	if err != nil {
+		return fmt.Errorf("unable to get signing root: %v", err)
+	}
+	if valid, err := blsVerify(signature[:], signingRoot[:], pubKey[:]); err != nil {
+		return err
+	} else if !valid {
+		return fmt.Errorf("invalid signature")
+	}
+
 	// [IGNORE] The block being voted for (attestation.data.beacon_block_root) has been seen (via both gossip and non-gossip sources)
 	// (a client MAY queue attestations for processing once block is retrieved).
 	if _, ok := s.forkchoiceStore.GetHeader(root); !ok {