package types import ( "bytes" "errors" "fmt" "strings" "time" "github.com/tendermint/tendermint/crypto" cryptoenc "github.com/tendermint/tendermint/crypto/encoding" "github.com/tendermint/tendermint/crypto/merkle" "github.com/tendermint/tendermint/crypto/tmhash" tmjson "github.com/tendermint/tendermint/libs/json" tmmath "github.com/tendermint/tendermint/libs/math" tmrand "github.com/tendermint/tendermint/libs/rand" tmproto "github.com/tendermint/tendermint/proto/tendermint/types" ) const ( // MaxEvidenceBytes is a maximum size of any evidence (including amino overhead). MaxEvidenceBytes int64 = 444 // An invalid field in the header from LunaticValidatorEvidence. // Must be a function of the ABCI application state. ValidatorsHashField = "ValidatorsHash" NextValidatorsHashField = "NextValidatorsHash" ConsensusHashField = "ConsensusHash" AppHashField = "AppHash" LastResultsHashField = "LastResultsHash" ) // ErrEvidenceInvalid wraps a piece of evidence and the error denoting how or why it is invalid. type ErrEvidenceInvalid struct { Evidence Evidence ErrorValue error } // NewErrEvidenceInvalid returns a new EvidenceInvalid with the given err. func NewErrEvidenceInvalid(ev Evidence, err error) *ErrEvidenceInvalid { return &ErrEvidenceInvalid{ev, err} } // Error returns a string representation of the error. func (err *ErrEvidenceInvalid) Error() string { return fmt.Sprintf("Invalid evidence: %v. Evidence: %v", err.ErrorValue, err.Evidence) } // ErrEvidenceOverflow is for when there is too much evidence in a block. type ErrEvidenceOverflow struct { MaxNum int GotNum int } // NewErrEvidenceOverflow returns a new ErrEvidenceOverflow where got > max. func NewErrEvidenceOverflow(max, got int) *ErrEvidenceOverflow { return &ErrEvidenceOverflow{max, got} } // Error returns a string representation of the error. func (err *ErrEvidenceOverflow) Error() string { return fmt.Sprintf("Too much evidence: Max %d, got %d", err.MaxNum, err.GotNum) } //------------------------------------------- // Evidence represents any provable malicious activity by a validator. type Evidence interface { Height() int64 // height of the equivocation Time() time.Time // time of the equivocation Address() []byte // address of the equivocating validator Bytes() []byte // bytes which comprise the evidence Hash() []byte // hash of the evidence Verify(chainID string, pubKey crypto.PubKey) error // verify the evidence Equal(Evidence) bool // check equality of evidence ValidateBasic() error String() string } type CompositeEvidence interface { VerifyComposite(committedHeader *Header, valSet *ValidatorSet) error Split(committedHeader *Header, valSet *ValidatorSet) []Evidence } func EvidenceToProto(evidence Evidence) (*tmproto.Evidence, error) { if evidence == nil { return nil, errors.New("nil evidence") } switch evi := evidence.(type) { case *DuplicateVoteEvidence: pbevi := evi.ToProto() tp := &tmproto.Evidence{ Sum: &tmproto.Evidence_DuplicateVoteEvidence{ DuplicateVoteEvidence: pbevi, }, } return tp, nil case *ConflictingHeadersEvidence: pbevi := evi.ToProto() tp := &tmproto.Evidence{ Sum: &tmproto.Evidence_ConflictingHeadersEvidence{ ConflictingHeadersEvidence: pbevi, }, } return tp, nil case *LunaticValidatorEvidence: pbevi := evi.ToProto() tp := &tmproto.Evidence{ Sum: &tmproto.Evidence_LunaticValidatorEvidence{ LunaticValidatorEvidence: pbevi, }, } return tp, nil case *PotentialAmnesiaEvidence: pbevi := evi.ToProto() tp := &tmproto.Evidence{ Sum: &tmproto.Evidence_PotentialAmnesiaEvidence{ PotentialAmnesiaEvidence: pbevi, }, } return tp, nil case *AmnesiaEvidence: aepb := evi.ToProto() tp := &tmproto.Evidence{ Sum: &tmproto.Evidence_AmnesiaEvidence{ AmnesiaEvidence: aepb, }, } return tp, nil default: return nil, fmt.Errorf("toproto: evidence is not recognized: %T", evi) } } func EvidenceFromProto(evidence *tmproto.Evidence) (Evidence, error) { if evidence == nil { return nil, errors.New("nil evidence") } switch evi := evidence.Sum.(type) { case *tmproto.Evidence_DuplicateVoteEvidence: return DuplicateVoteEvidenceFromProto(evi.DuplicateVoteEvidence) case *tmproto.Evidence_ConflictingHeadersEvidence: return ConflictingHeadersEvidenceFromProto(evi.ConflictingHeadersEvidence) case *tmproto.Evidence_LunaticValidatorEvidence: return LunaticValidatorEvidenceFromProto(evi.LunaticValidatorEvidence) case *tmproto.Evidence_PotentialAmnesiaEvidence: return PotentialAmnesiaEvidenceFromProto(evi.PotentialAmnesiaEvidence) case *tmproto.Evidence_AmnesiaEvidence: return AmnesiaEvidenceFromProto(evi.AmnesiaEvidence) default: return nil, errors.New("evidence is not recognized") } } func init() { tmjson.RegisterType(&DuplicateVoteEvidence{}, "tendermint/DuplicateVoteEvidence") tmjson.RegisterType(&ConflictingHeadersEvidence{}, "tendermint/ConflictingHeadersEvidence") tmjson.RegisterType(&LunaticValidatorEvidence{}, "tendermint/LunaticValidatorEvidence") tmjson.RegisterType(&PotentialAmnesiaEvidence{}, "tendermint/PotentialAmnesiaEvidence") tmjson.RegisterType(&AmnesiaEvidence{}, "tendermint/AmnesiaEvidence") } //------------------------------------------- // DuplicateVoteEvidence contains evidence a validator signed two conflicting // votes. type DuplicateVoteEvidence struct { VoteA *Vote `json:"vote_a"` VoteB *Vote `json:"vote_b"` Timestamp time.Time `json:"timestamp"` } var _ Evidence = &DuplicateVoteEvidence{} // NewDuplicateVoteEvidence creates DuplicateVoteEvidence with right ordering given // two conflicting votes. If one of the votes is nil, evidence returned is nil as well func NewDuplicateVoteEvidence(vote1, vote2 *Vote, time time.Time) *DuplicateVoteEvidence { var voteA, voteB *Vote if vote1 == nil || vote2 == nil { return nil } if strings.Compare(vote1.BlockID.Key(), vote2.BlockID.Key()) == -1 { voteA = vote1 voteB = vote2 } else { voteA = vote2 voteB = vote1 } return &DuplicateVoteEvidence{ VoteA: voteA, VoteB: voteB, Timestamp: time, } } // String returns a string representation of the evidence. func (dve *DuplicateVoteEvidence) String() string { return fmt.Sprintf("DuplicateVoteEvidence{VoteA: %v, VoteB: %v, Time: %v}", dve.VoteA, dve.VoteB, dve.Timestamp) } // Height returns the height this evidence refers to. func (dve *DuplicateVoteEvidence) Height() int64 { return dve.VoteA.Height } // Time returns time of the latest vote. func (dve *DuplicateVoteEvidence) Time() time.Time { return dve.Timestamp } // Address returns the address of the validator. func (dve *DuplicateVoteEvidence) Address() []byte { return dve.VoteA.ValidatorAddress } // Hash returns the hash of the evidence. func (dve *DuplicateVoteEvidence) Bytes() []byte { pbe := dve.ToProto() bz, err := pbe.Marshal() if err != nil { panic(err) } return bz } // Hash returns the hash of the evidence. func (dve *DuplicateVoteEvidence) Hash() []byte { pbe := dve.ToProto() bz, err := pbe.Marshal() if err != nil { panic(err) } return tmhash.Sum(bz) } // Verify returns an error if the two votes aren't conflicting. // // To be conflicting, they must be from the same validator, for the same H/R/S, // but for different blocks. func (dve *DuplicateVoteEvidence) Verify(chainID string, pubKey crypto.PubKey) error { // H/R/S must be the same if dve.VoteA.Height != dve.VoteB.Height || dve.VoteA.Round != dve.VoteB.Round || dve.VoteA.Type != dve.VoteB.Type { return fmt.Errorf("h/r/s does not match: %d/%d/%v vs %d/%d/%v", dve.VoteA.Height, dve.VoteA.Round, dve.VoteA.Type, dve.VoteB.Height, dve.VoteB.Round, dve.VoteB.Type) } // Address must be the same if !bytes.Equal(dve.VoteA.ValidatorAddress, dve.VoteB.ValidatorAddress) { return fmt.Errorf("validator addresses do not match: %X vs %X", dve.VoteA.ValidatorAddress, dve.VoteB.ValidatorAddress, ) } // BlockIDs must be different if dve.VoteA.BlockID.Equals(dve.VoteB.BlockID) { return fmt.Errorf( "block IDs are the same (%v) - not a real duplicate vote", dve.VoteA.BlockID, ) } // pubkey must match address (this should already be true, sanity check) addr := dve.VoteA.ValidatorAddress if !bytes.Equal(pubKey.Address(), addr) { return fmt.Errorf("address (%X) doesn't match pubkey (%v - %X)", addr, pubKey, pubKey.Address()) } va := dve.VoteA.ToProto() vb := dve.VoteB.ToProto() // Signatures must be valid if !pubKey.VerifySignature(VoteSignBytes(chainID, va), dve.VoteA.Signature) { return fmt.Errorf("verifying VoteA: %w", ErrVoteInvalidSignature) } if !pubKey.VerifySignature(VoteSignBytes(chainID, vb), dve.VoteB.Signature) { return fmt.Errorf("verifying VoteB: %w", ErrVoteInvalidSignature) } return nil } // Equal checks if two pieces of evidence are equal. func (dve *DuplicateVoteEvidence) Equal(ev Evidence) bool { if _, ok := ev.(*DuplicateVoteEvidence); !ok { return false } pbdev := dve.ToProto() bz, err := pbdev.Marshal() if err != nil { panic(err) } var evbz []byte if ev, ok := ev.(*DuplicateVoteEvidence); ok { evpb := ev.ToProto() evbz, err = evpb.Marshal() if err != nil { panic(err) } } // just check their hashes dveHash := tmhash.Sum(bz) evHash := tmhash.Sum(evbz) return bytes.Equal(dveHash, evHash) } // ValidateBasic performs basic validation. func (dve *DuplicateVoteEvidence) ValidateBasic() error { if dve == nil { return errors.New("empty duplicate vote evidence") } if dve.VoteA == nil || dve.VoteB == nil { return fmt.Errorf("one or both of the votes are empty %v, %v", dve.VoteA, dve.VoteB) } if err := dve.VoteA.ValidateBasic(); err != nil { return fmt.Errorf("invalid VoteA: %w", err) } if err := dve.VoteB.ValidateBasic(); err != nil { return fmt.Errorf("invalid VoteB: %w", err) } // Enforce Votes are lexicographically sorted on blockID if strings.Compare(dve.VoteA.BlockID.Key(), dve.VoteB.BlockID.Key()) >= 0 { return errors.New("duplicate votes in invalid order") } return nil } func (dve *DuplicateVoteEvidence) ToProto() *tmproto.DuplicateVoteEvidence { voteB := dve.VoteB.ToProto() voteA := dve.VoteA.ToProto() tp := tmproto.DuplicateVoteEvidence{ VoteA: voteA, VoteB: voteB, Timestamp: dve.Timestamp, } return &tp } func DuplicateVoteEvidenceFromProto(pb *tmproto.DuplicateVoteEvidence) (*DuplicateVoteEvidence, error) { if pb == nil { return nil, errors.New("nil duplicate vote evidence") } vA, err := VoteFromProto(pb.VoteA) if err != nil { return nil, err } vB, err := VoteFromProto(pb.VoteB) if err != nil { return nil, err } dve := NewDuplicateVoteEvidence(vA, vB, pb.Timestamp) return dve, dve.ValidateBasic() } // ConflictingHeadersEvidence is primarily used by the light client when it // observes two conflicting headers, both having 1/3+ of the voting power of // the currently trusted validator set. type ConflictingHeadersEvidence struct { H1 *SignedHeader `json:"h_1"` H2 *SignedHeader `json:"h_2"` } var _ Evidence = &ConflictingHeadersEvidence{} var _ CompositeEvidence = &ConflictingHeadersEvidence{} // NewConflictingHeadersEvidence creates a new instance of the respective evidence func NewConflictingHeadersEvidence(h1, h2 *SignedHeader) *ConflictingHeadersEvidence { return &ConflictingHeadersEvidence{H1: h1, H2: h2} } // Split breaks up evidence into smaller chunks of evidence: // LunaticValidatorEvidence, DuplicateVoteEvidence and // PotentialAmnesiaEvidence. // // committedHeader - header at height H1.Height == H2.Height // valSet - validator set at height H1.Height == H2.Height func (ev *ConflictingHeadersEvidence) Split(committedHeader *Header, valSet *ValidatorSet) []Evidence { evList := make([]Evidence, 0) var alternativeHeader *SignedHeader if bytes.Equal(committedHeader.Hash(), ev.H1.Hash()) { alternativeHeader = ev.H2 } else { alternativeHeader = ev.H1 } // If ValidatorsHash, NextValidatorsHash, ConsensusHash, AppHash, and // LastResultsHash in alternativeHeader are different (incorrect application // state transition), then it is a lunatic misbehavior => immediately // slashable (#F5). var invalidField string switch { case !bytes.Equal(committedHeader.ValidatorsHash, alternativeHeader.ValidatorsHash): invalidField = "ValidatorsHash" case !bytes.Equal(committedHeader.NextValidatorsHash, alternativeHeader.NextValidatorsHash): invalidField = "NextValidatorsHash" case !bytes.Equal(committedHeader.ConsensusHash, alternativeHeader.ConsensusHash): invalidField = "ConsensusHash" case !bytes.Equal(committedHeader.AppHash, alternativeHeader.AppHash): invalidField = "AppHash" case !bytes.Equal(committedHeader.LastResultsHash, alternativeHeader.LastResultsHash): invalidField = "LastResultsHash" } if invalidField != "" { for i, sig := range alternativeHeader.Commit.Signatures { if sig.Absent() { continue } evList = append(evList, NewLunaticValidatorEvidence( alternativeHeader.Header, alternativeHeader.Commit.GetVote(int32(i)), invalidField, committedHeader.Time, //take the time of our own trusted header )) } return evList } // Use the fact that signatures are sorted by ValidatorAddress. var ( i = 0 j = 0 ) OUTER_LOOP: for i < len(ev.H1.Commit.Signatures) { sigA := ev.H1.Commit.Signatures[i] if sigA.Absent() { i++ continue } // FIXME: Replace with HasAddress once DuplicateVoteEvidence#PubKey is // removed. _, val := valSet.GetByAddress(sigA.ValidatorAddress) if val == nil { i++ continue } for j < len(ev.H2.Commit.Signatures) { sigB := ev.H2.Commit.Signatures[j] if sigB.Absent() { j++ continue } switch bytes.Compare(sigA.ValidatorAddress, sigB.ValidatorAddress) { case 0: // if H1.Round == H2.Round, and some signers signed different precommit // messages in both commits, then it is an equivocation misbehavior => // immediately slashable (#F1). if ev.H1.Commit.Round == ev.H2.Commit.Round { evList = append(evList, NewDuplicateVoteEvidence( ev.H1.Commit.GetVote(int32(i)), ev.H2.Commit.GetVote(int32(j)), ev.H1.Time, )) } else { // if H1.Round != H2.Round we need to run full detection procedure => not // immediately slashable. firstVote := ev.H1.Commit.GetVote(int32(i)) secondVote := ev.H2.Commit.GetVote(int32(j)) newEv := NewPotentialAmnesiaEvidence(firstVote, secondVote, committedHeader.Time) // has the validator incorrectly voted for a previous round if newEv.VoteA.Round > newEv.VoteB.Round { evList = append(evList, NewAmnesiaEvidence(newEv, NewEmptyPOLC())) } else { evList = append(evList, newEv) } } i++ j++ continue OUTER_LOOP case 1: i++ continue OUTER_LOOP case -1: j++ } } } return evList } func (ev *ConflictingHeadersEvidence) Height() int64 { return ev.H1.Height } // Time returns time of the latest header. func (ev *ConflictingHeadersEvidence) Time() time.Time { return maxTime(ev.H1.Time, ev.H2.Time) } func (ev *ConflictingHeadersEvidence) Address() []byte { panic("use ConflictingHeadersEvidence#Split to split evidence into individual pieces") } func (ev *ConflictingHeadersEvidence) Bytes() []byte { pbe := ev.ToProto() bz, err := pbe.Marshal() if err != nil { panic(err) } return bz } func (ev *ConflictingHeadersEvidence) Hash() []byte { bz := make([]byte, tmhash.Size*2) copy(bz[:tmhash.Size-1], ev.H1.Hash().Bytes()) copy(bz[tmhash.Size:], ev.H2.Hash().Bytes()) return tmhash.Sum(bz) } func (ev *ConflictingHeadersEvidence) Verify(chainID string, _ crypto.PubKey) error { panic("use ConflictingHeadersEvidence#VerifyComposite to verify composite evidence") } // VerifyComposite verifies that both headers belong to the same chain, same // height and signed by 1/3+ of validators at height H1.Height == H2.Height. func (ev *ConflictingHeadersEvidence) VerifyComposite(committedHeader *Header, valSet *ValidatorSet) error { var alternativeHeader *SignedHeader switch { case bytes.Equal(committedHeader.Hash(), ev.H1.Hash()): alternativeHeader = ev.H2 case bytes.Equal(committedHeader.Hash(), ev.H2.Hash()): alternativeHeader = ev.H1 default: return errors.New("none of the headers are committed from this node's perspective") } // ChainID must be the same if committedHeader.ChainID != alternativeHeader.ChainID { return errors.New("alt header is from a different chain") } // Height must be the same if committedHeader.Height != alternativeHeader.Height { return errors.New("alt header is from a different height") } // Limit the number of signatures to avoid DoS attacks where a header // contains too many signatures. // // Validator set size = 100 [node] // Max validator set size = 100 * 2 = 200 [fork?] maxNumValidators := valSet.Size() * 2 if len(alternativeHeader.Commit.Signatures) > maxNumValidators { return fmt.Errorf("alt commit contains too many signatures: %d, expected no more than %d", len(alternativeHeader.Commit.Signatures), maxNumValidators) } // Header must be signed by at least 1/3+ of voting power of currently // trusted validator set. if err := valSet.VerifyCommitLightTrusting( alternativeHeader.ChainID, alternativeHeader.Commit, tmmath.Fraction{Numerator: 1, Denominator: 3}); err != nil { return fmt.Errorf("alt header does not have 1/3+ of voting power of our validator set: %w", err) } return nil } func (ev *ConflictingHeadersEvidence) Equal(ev2 Evidence) bool { if e2, ok := ev2.(*ConflictingHeadersEvidence); ok { return bytes.Equal(ev.H1.Hash(), e2.H1.Hash()) && bytes.Equal(ev.H2.Hash(), e2.H2.Hash()) } return false } func (ev *ConflictingHeadersEvidence) ValidateBasic() error { if ev == nil { return errors.New("empty conflicting headers evidence") } if ev.H1 == nil { return errors.New("first header is missing") } if ev.H2 == nil { return errors.New("second header is missing") } if err := ev.H1.ValidateBasic(ev.H1.ChainID); err != nil { return fmt.Errorf("h1: %w", err) } if err := ev.H2.ValidateBasic(ev.H2.ChainID); err != nil { return fmt.Errorf("h2: %w", err) } return nil } func (ev *ConflictingHeadersEvidence) String() string { return fmt.Sprintf("ConflictingHeadersEvidence{H1: %d#%X, H2: %d#%X}", ev.H1.Height, ev.H1.Hash(), ev.H2.Height, ev.H2.Hash()) } func (ev *ConflictingHeadersEvidence) ToProto() *tmproto.ConflictingHeadersEvidence { pbh1 := ev.H1.ToProto() pbh2 := ev.H2.ToProto() tp := &tmproto.ConflictingHeadersEvidence{ H1: pbh1, H2: pbh2, } return tp } func ConflictingHeadersEvidenceFromProto(pb *tmproto.ConflictingHeadersEvidence) (*ConflictingHeadersEvidence, error) { if pb == nil { return &ConflictingHeadersEvidence{}, errors.New("nil ConflictingHeadersEvidence") } h1, err := SignedHeaderFromProto(pb.H1) if err != nil { return &ConflictingHeadersEvidence{}, fmt.Errorf("from proto err: %w", err) } h2, err := SignedHeaderFromProto(pb.H2) if err != nil { return &ConflictingHeadersEvidence{}, fmt.Errorf("from proto err: %w", err) } tp := &ConflictingHeadersEvidence{ H1: h1, H2: h2, } return tp, tp.ValidateBasic() } //------------------------------------------- type LunaticValidatorEvidence struct { Header *Header `json:"header"` Vote *Vote `json:"vote"` InvalidHeaderField string `json:"invalid_header_field"` Timestamp time.Time `json:"timestamp"` } var _ Evidence = &LunaticValidatorEvidence{} // NewLunaticValidatorEvidence creates a new instance of the respective evidence func NewLunaticValidatorEvidence(header *Header, vote *Vote, invalidHeaderField string, time time.Time) *LunaticValidatorEvidence { return &LunaticValidatorEvidence{ Header: header, Vote: vote, InvalidHeaderField: invalidHeaderField, Timestamp: time, } } func (e *LunaticValidatorEvidence) Height() int64 { return e.Header.Height } // Time returns the maximum between the header's time and vote's time. func (e *LunaticValidatorEvidence) Time() time.Time { return e.Timestamp } func (e *LunaticValidatorEvidence) Address() []byte { return e.Vote.ValidatorAddress } func (e *LunaticValidatorEvidence) Hash() []byte { bz := make([]byte, tmhash.Size+crypto.AddressSize) copy(bz[:tmhash.Size-1], e.Header.Hash().Bytes()) copy(bz[tmhash.Size:], e.Vote.ValidatorAddress.Bytes()) return tmhash.Sum(bz) } func (e *LunaticValidatorEvidence) Bytes() []byte { pbe := e.ToProto() bz, err := pbe.Marshal() if err != nil { panic(err) } return bz } func (e *LunaticValidatorEvidence) Verify(chainID string, pubKey crypto.PubKey) error { // chainID must be the same if chainID != e.Header.ChainID { return fmt.Errorf("chainID do not match: %s vs %s", chainID, e.Header.ChainID, ) } v := e.Vote.ToProto() if !pubKey.VerifySignature(VoteSignBytes(chainID, v), e.Vote.Signature) { return errors.New("invalid signature") } return nil } func (e *LunaticValidatorEvidence) Equal(ev Evidence) bool { if e2, ok := ev.(*LunaticValidatorEvidence); ok { return bytes.Equal(e.Header.Hash(), e2.Header.Hash()) && bytes.Equal(e.Vote.ValidatorAddress, e2.Vote.ValidatorAddress) } return false } func (e *LunaticValidatorEvidence) ValidateBasic() error { if e == nil { return errors.New("empty lunatic validator evidence") } if e.Header == nil { return errors.New("empty header") } if e.Vote == nil { return errors.New("empty vote") } if err := e.Header.ValidateBasic(); err != nil { return fmt.Errorf("invalid header: %v", err) } if err := e.Vote.ValidateBasic(); err != nil { return fmt.Errorf("invalid signature: %v", err) } if !e.Vote.BlockID.IsComplete() { return errors.New("expected vote for block") } if e.Header.Height != e.Vote.Height { return fmt.Errorf("header and vote have different heights: %d vs %d", e.Header.Height, e.Vote.Height, ) } switch e.InvalidHeaderField { case "ValidatorsHash", "NextValidatorsHash", "ConsensusHash", "AppHash", "LastResultsHash": break default: return errors.New("unknown invalid header field") } if !bytes.Equal(e.Header.Hash(), e.Vote.BlockID.Hash) { return fmt.Errorf("vote was not for header: %X != %X", e.Vote.BlockID.Hash, e.Header.Hash(), ) } return nil } func (e *LunaticValidatorEvidence) String() string { return fmt.Sprintf("LunaticValidatorEvidence{%X voted for %d/%X, which contains invalid %s}", e.Vote.ValidatorAddress, e.Header.Height, e.Header.Hash(), e.InvalidHeaderField) } func (e *LunaticValidatorEvidence) VerifyHeader(committedHeader *Header) error { matchErr := func(field string) error { return fmt.Errorf("%s matches committed hash", field) } if committedHeader == nil { return errors.New("committed header is nil") } switch e.InvalidHeaderField { case ValidatorsHashField: if bytes.Equal(committedHeader.ValidatorsHash, e.Header.ValidatorsHash) { return matchErr(ValidatorsHashField) } case NextValidatorsHashField: if bytes.Equal(committedHeader.NextValidatorsHash, e.Header.NextValidatorsHash) { return matchErr(NextValidatorsHashField) } case ConsensusHashField: if bytes.Equal(committedHeader.ConsensusHash, e.Header.ConsensusHash) { return matchErr(ConsensusHashField) } case AppHashField: if bytes.Equal(committedHeader.AppHash, e.Header.AppHash) { return matchErr(AppHashField) } case LastResultsHashField: if bytes.Equal(committedHeader.LastResultsHash, e.Header.LastResultsHash) { return matchErr(LastResultsHashField) } default: return errors.New("unknown InvalidHeaderField") } return nil } func (e *LunaticValidatorEvidence) ToProto() *tmproto.LunaticValidatorEvidence { h := e.Header.ToProto() v := e.Vote.ToProto() tp := &tmproto.LunaticValidatorEvidence{ Header: h, Vote: v, InvalidHeaderField: e.InvalidHeaderField, Timestamp: e.Timestamp, } return tp } func LunaticValidatorEvidenceFromProto(pb *tmproto.LunaticValidatorEvidence) (*LunaticValidatorEvidence, error) { if pb == nil { return nil, errors.New("nil LunaticValidatorEvidence") } h, err := HeaderFromProto(pb.GetHeader()) if err != nil { return nil, err } v, err := VoteFromProto(pb.GetVote()) if err != nil { return nil, err } tp := LunaticValidatorEvidence{ Header: &h, Vote: v, InvalidHeaderField: pb.InvalidHeaderField, Timestamp: pb.Timestamp, } return &tp, tp.ValidateBasic() } //------------------------------------------- // PotentialAmnesiaEvidence is constructed when a validator votes on two different blocks at different rounds // in the same height. PotentialAmnesiaEvidence can then evolve into AmnesiaEvidence if the indicted validator // is incapable of providing the proof of lock change that validates voting twice in the allotted trial period. // Heightstamp is used for each node to keep a track of how much time has passed so as to know when the trial period // is finished and is set when the node first receives the evidence. Votes are ordered based on their timestamp type PotentialAmnesiaEvidence struct { VoteA *Vote `json:"vote_a"` VoteB *Vote `json:"vote_b"` HeightStamp int64 Timestamp time.Time `json:"timestamp"` } var _ Evidence = &PotentialAmnesiaEvidence{} // NewPotentialAmnesiaEvidence creates a new instance of the evidence and orders the votes correctly func NewPotentialAmnesiaEvidence(voteA, voteB *Vote, time time.Time) *PotentialAmnesiaEvidence { if voteA == nil || voteB == nil { return nil } if voteA.Timestamp.Before(voteB.Timestamp) { return &PotentialAmnesiaEvidence{VoteA: voteA, VoteB: voteB, Timestamp: time} } return &PotentialAmnesiaEvidence{VoteA: voteB, VoteB: voteA, Timestamp: time} } func (e *PotentialAmnesiaEvidence) Height() int64 { return e.VoteA.Height } func (e *PotentialAmnesiaEvidence) Time() time.Time { return e.Timestamp } func (e *PotentialAmnesiaEvidence) Address() []byte { return e.VoteA.ValidatorAddress } // NOTE: Heightstamp must not be included in hash func (e *PotentialAmnesiaEvidence) Hash() []byte { v1, err := e.VoteA.ToProto().Marshal() if err != nil { panic(fmt.Errorf("trying to hash potential amnesia evidence, err: %w", err)) } v2, err := e.VoteB.ToProto().Marshal() if err != nil { panic(fmt.Errorf("trying to hash potential amnesia evidence, err: %w", err)) } return tmhash.Sum(append(v1, v2...)) } func (e *PotentialAmnesiaEvidence) Bytes() []byte { pbe := e.ToProto() bz, err := pbe.Marshal() if err != nil { panic(err) } return bz } func (e *PotentialAmnesiaEvidence) Verify(chainID string, pubKey crypto.PubKey) error { // pubkey must match address (this should already be true, sanity check) addr := e.VoteA.ValidatorAddress if !bytes.Equal(pubKey.Address(), addr) { return fmt.Errorf("address (%X) doesn't match pubkey (%v - %X)", addr, pubKey, pubKey.Address()) } va := e.VoteA.ToProto() vb := e.VoteB.ToProto() // Signatures must be valid if !pubKey.VerifySignature(VoteSignBytes(chainID, va), e.VoteA.Signature) { return fmt.Errorf("verifying VoteA: %w", ErrVoteInvalidSignature) } if !pubKey.VerifySignature(VoteSignBytes(chainID, vb), e.VoteB.Signature) { return fmt.Errorf("verifying VoteB: %w", ErrVoteInvalidSignature) } return nil } func (e *PotentialAmnesiaEvidence) Equal(ev Evidence) bool { if e2, ok := ev.(*PotentialAmnesiaEvidence); ok { return e.Height() == e2.Height() && e.VoteA.Round == e2.VoteA.Round && e.VoteB.Round == e2.VoteB.Round && bytes.Equal(e.Address(), e2.Address()) } return false } func (e *PotentialAmnesiaEvidence) ValidateBasic() error { if e == nil { return errors.New("empty potential amnesia evidence") } if e.VoteA == nil || e.VoteB == nil { return fmt.Errorf("one or both of the votes are empty %v, %v", e.VoteA, e.VoteB) } if err := e.VoteA.ValidateBasic(); err != nil { return fmt.Errorf("invalid VoteA: %v", err) } if err := e.VoteB.ValidateBasic(); err != nil { return fmt.Errorf("invalid VoteB: %v", err) } // H/S must be the same if e.VoteA.Height != e.VoteB.Height { return fmt.Errorf("heights do not match: %d vs %d", e.VoteA.Height, e.VoteB.Height) } if e.VoteA.Round == e.VoteB.Round { return fmt.Errorf("votes must be for different rounds: %d", e.VoteA.Round) } // Enforce that vote A came before vote B if e.VoteA.Timestamp.After(e.VoteB.Timestamp) { return fmt.Errorf("vote A should have a timestamp before vote B, but got %s > %s", e.VoteA.Timestamp, e.VoteB.Timestamp) } // Address must be the same if !bytes.Equal(e.VoteA.ValidatorAddress, e.VoteB.ValidatorAddress) { return fmt.Errorf("validator addresses do not match: %X vs %X", e.VoteA.ValidatorAddress, e.VoteB.ValidatorAddress, ) } if e.VoteA.BlockID.IsZero() { return errors.New("first vote is for a nil block - voter hasn't locked on a block") } // BlockIDs must be different if e.VoteA.BlockID.Equals(e.VoteB.BlockID) { return fmt.Errorf( "block IDs are the same (%v) - not a real duplicate vote", e.VoteA.BlockID, ) } return nil } func (e *PotentialAmnesiaEvidence) String() string { return fmt.Sprintf("PotentialAmnesiaEvidence{VoteA: %v, VoteB: %v}", e.VoteA, e.VoteB) } // Primed finds whether the PotentialAmnesiaEvidence is ready to be upgraded to Amnesia Evidence. It is decided if // either the prosecuted node voted in the past or if the allocated trial period has expired without a proof of lock // change having been provided. func (e *PotentialAmnesiaEvidence) Primed(trialPeriod, currentHeight int64) bool { // voted in the past can be instantly punishable if e.VoteA.Round > e.VoteB.Round { return true } // has the trial period expired if e.HeightStamp > 0 { return e.HeightStamp+trialPeriod <= currentHeight } return false } func (e *PotentialAmnesiaEvidence) ToProto() *tmproto.PotentialAmnesiaEvidence { voteB := e.VoteB.ToProto() voteA := e.VoteA.ToProto() tp := &tmproto.PotentialAmnesiaEvidence{ VoteA: voteA, VoteB: voteB, HeightStamp: e.HeightStamp, Timestamp: e.Timestamp, } return tp } // ------------------ // ProofOfLockChange (POLC) proves that a node followed the consensus protocol and voted for a precommit in two // different rounds because the node received a majority of votes for a different block in the latter round. In cases of // amnesia evidence, a suspected node will need ProofOfLockChange to prove that the node did not break protocol. type ProofOfLockChange struct { Votes []*Vote `json:"votes"` PubKey crypto.PubKey `json:"pubkey"` } // MakePOLCFromVoteSet can be used when a majority of prevotes or precommits for a block is seen // that the node has itself not yet voted for in order to process the vote set into a proof of lock change func NewPOLCFromVoteSet(voteSet *VoteSet, pubKey crypto.PubKey, blockID BlockID) (*ProofOfLockChange, error) { polc := newPOLCFromVoteSet(voteSet, pubKey, blockID) return polc, polc.ValidateBasic() } func newPOLCFromVoteSet(voteSet *VoteSet, pubKey crypto.PubKey, blockID BlockID) *ProofOfLockChange { if voteSet == nil { return nil } var votes []*Vote valSetSize := voteSet.Size() for valIdx := int32(0); int(valIdx) < valSetSize; valIdx++ { vote := voteSet.GetByIndex(valIdx) if vote != nil && vote.BlockID.Equals(blockID) { votes = append(votes, vote) } } return NewPOLC(votes, pubKey) } // NewPOLC creates a POLC func NewPOLC(votes []*Vote, pubKey crypto.PubKey) *ProofOfLockChange { return &ProofOfLockChange{ Votes: votes, PubKey: pubKey, } } // EmptyPOLC returns an empty polc. This is used when no polc has been provided in the allocated trial period time // and the node now needs to move to upgrading to AmnesiaEvidence and hence uses an empty polc func NewEmptyPOLC() *ProofOfLockChange { return &ProofOfLockChange{ nil, nil, } } func (e *ProofOfLockChange) Height() int64 { return e.Votes[0].Height } // Time returns time of the latest vote. func (e *ProofOfLockChange) Time() time.Time { latest := e.Votes[0].Timestamp for _, vote := range e.Votes { if vote.Timestamp.After(latest) { latest = vote.Timestamp } } return latest } func (e *ProofOfLockChange) Round() int32 { return e.Votes[0].Round } func (e *ProofOfLockChange) Address() []byte { return e.PubKey.Address() } func (e *ProofOfLockChange) BlockID() BlockID { return e.Votes[0].BlockID } // ValidateVotes checks the polc against the validator set of that height. The function makes sure that the polc // contains a majority of votes and that each func (e *ProofOfLockChange) ValidateVotes(valSet *ValidatorSet, chainID string) error { if e.IsAbsent() { return errors.New("polc is empty") } talliedVotingPower := int64(0) votingPowerNeeded := valSet.TotalVotingPower() * 2 / 3 for _, vote := range e.Votes { exists := false for _, validator := range valSet.Validators { if bytes.Equal(validator.Address, vote.ValidatorAddress) { exists = true v := vote.ToProto() if !validator.PubKey.VerifySignature(VoteSignBytes(chainID, v), vote.Signature) { return fmt.Errorf("cannot verify vote (from validator: %d) against signature: %v", vote.ValidatorIndex, vote.Signature) } talliedVotingPower += validator.VotingPower } } if !exists { return fmt.Errorf("vote was not from a validator in this set: %v", vote.String()) } } if talliedVotingPower <= votingPowerNeeded { return ErrNotEnoughVotingPowerSigned{ Got: talliedVotingPower, Needed: votingPowerNeeded + 1, } } return nil } func (e *ProofOfLockChange) Equal(e2 *ProofOfLockChange) bool { return bytes.Equal(e.Address(), e2.Address()) && e.Height() == e2.Height() && e.Round() == e2.Round() } func (e *ProofOfLockChange) ValidateBasic() error { if e == nil { return errors.New("empty proof of lock change") } // first check if the polc is absent / empty if e.IsAbsent() { return nil } if e.PubKey == nil { return errors.New("missing public key") } // validate basic doesn't count the number of votes and their voting power, this is to be done by VerifyEvidence if e.Votes == nil || len(e.Votes) == 0 { return errors.New("missing votes") } // height, round and vote type must be the same for all votes height := e.Height() round := e.Round() if round == 0 { return errors.New("can't have a polc for the first round") } voteType := e.Votes[0].Type for idx, vote := range e.Votes { if vote == nil { return fmt.Errorf("nil vote at index: %d", idx) } if err := vote.ValidateBasic(); err != nil { return fmt.Errorf("invalid vote#%d: %w", idx, err) } if vote.Height != height { return fmt.Errorf("invalid height for vote#%d: %d instead of %d", idx, vote.Height, height) } if vote.Round != round { return fmt.Errorf("invalid round for vote#%d: %d instead of %d", idx, vote.Round, round) } if vote.Type != voteType { return fmt.Errorf("invalid vote type for vote#%d: %d instead of %d", idx, vote.Type, voteType) } if !vote.BlockID.Equals(e.BlockID()) { return fmt.Errorf("vote must be for the same block id: %v instead of %v", e.BlockID(), vote.BlockID) } if bytes.Equal(vote.ValidatorAddress.Bytes(), e.PubKey.Address().Bytes()) { return fmt.Errorf("vote validator address cannot be the same as the public key address: %X all votes %v", vote.ValidatorAddress.Bytes(), e.PubKey.Address().Bytes()) } for i := idx + 1; i < len(e.Votes); i++ { if bytes.Equal(vote.ValidatorAddress.Bytes(), e.Votes[i].ValidatorAddress.Bytes()) { return fmt.Errorf("duplicate votes: %v", vote) } } } return nil } func (e *ProofOfLockChange) String() string { if e.IsAbsent() { return "Empty ProofOfLockChange" } return fmt.Sprintf("ProofOfLockChange {Address: %X, Height: %d, Round: %d", e.Address(), e.Height(), e.Votes[0].Round) } // IsAbsent checks if the polc is empty func (e *ProofOfLockChange) IsAbsent() bool { return e.Votes == nil && e.PubKey == nil } func (e *ProofOfLockChange) ToProto() (*tmproto.ProofOfLockChange, error) { plc := new(tmproto.ProofOfLockChange) vpb := make([]*tmproto.Vote, len(e.Votes)) // if absent create empty proto polc if e.IsAbsent() { return plc, nil } if e.Votes == nil { return plc, errors.New("invalid proof of lock change (no votes), did you forget to validate?") } for i, v := range e.Votes { pb := v.ToProto() if pb != nil { vpb[i] = pb } } pk, err := cryptoenc.PubKeyToProto(e.PubKey) if err != nil { return plc, fmt.Errorf("invalid proof of lock change (err: %w), did you forget to validate?", err) } plc.PubKey = &pk plc.Votes = vpb return plc, nil } // AmnesiaEvidence is the progression of PotentialAmnesiaEvidence and is used to prove an infringement of the // Tendermint consensus when a validator incorrectly sends a vote in a later round without correctly changing the lock type AmnesiaEvidence struct { *PotentialAmnesiaEvidence Polc *ProofOfLockChange } // Height, Time, Address, and Verify, and Hash functions are all inherited by the PotentialAmnesiaEvidence struct var _ Evidence = &AmnesiaEvidence{} func NewAmnesiaEvidence(pe *PotentialAmnesiaEvidence, proof *ProofOfLockChange) *AmnesiaEvidence { return &AmnesiaEvidence{ pe, proof, } } // Note: Amnesia evidence with or without a polc are considered the same func (e *AmnesiaEvidence) Equal(ev Evidence) bool { if e2, ok := ev.(*AmnesiaEvidence); ok { return e.PotentialAmnesiaEvidence.Equal(e2.PotentialAmnesiaEvidence) } return false } func (e *AmnesiaEvidence) Bytes() []byte { pbe := e.ToProto() bz, err := pbe.Marshal() if err != nil { panic(fmt.Errorf("converting amnesia evidence to bytes, err: %w", err)) } return bz } func (e *AmnesiaEvidence) ValidateBasic() error { if e == nil { return errors.New("empty amnesia evidence") } if e.Polc == nil || e.PotentialAmnesiaEvidence == nil { return errors.New("amnesia evidence is missing either the polc or the potential amnesia evidence") } if err := e.PotentialAmnesiaEvidence.ValidateBasic(); err != nil { return fmt.Errorf("invalid potential amnesia evidence: %w", err) } if !e.Polc.IsAbsent() { if err := e.Polc.ValidateBasic(); err != nil { return fmt.Errorf("invalid proof of lock change: %w", err) } if !bytes.Equal(e.PotentialAmnesiaEvidence.Address(), e.Polc.Address()) { return fmt.Errorf("validator addresses do not match (%X - %X)", e.PotentialAmnesiaEvidence.Address(), e.Polc.Address()) } if e.PotentialAmnesiaEvidence.Height() != e.Polc.Height() { return fmt.Errorf("heights do not match (%d - %d)", e.PotentialAmnesiaEvidence.Height(), e.Polc.Height()) } if e.Polc.Round() <= e.VoteA.Round || e.Polc.Round() > e.VoteB.Round { return fmt.Errorf("polc must be between %d and %d (inclusive)", e.VoteA.Round+1, e.VoteB.Round) } if !e.Polc.BlockID().Equals(e.PotentialAmnesiaEvidence.VoteB.BlockID) && !e.Polc.BlockID().IsZero() { return fmt.Errorf("polc must be either for a nil block or for the same block as the second vote: %v != %v", e.Polc.BlockID(), e.PotentialAmnesiaEvidence.VoteB.BlockID) } if e.Polc.Time().After(e.PotentialAmnesiaEvidence.VoteB.Timestamp) { return fmt.Errorf("validator voted again before receiving a majority of votes for the new block: %v is after %v", e.Polc.Time(), e.PotentialAmnesiaEvidence.VoteB.Timestamp) } } return nil } // ViolatedConsensus assess on the basis of the AmnesiaEvidence whether the validator has violated the // Tendermint consensus. Evidence must be validated first (see ValidateBasic). // We are only interested in proving that the latter of the votes in terms of time was correctly done. func (e *AmnesiaEvidence) ViolatedConsensus() (bool, string) { // a validator having voted cannot go back and vote on an earlier round if e.PotentialAmnesiaEvidence.VoteA.Round > e.PotentialAmnesiaEvidence.VoteB.Round { return true, "validator went back and voted on a previous round" } // if empty, then no proof was provided to defend the validators actions if e.Polc.IsAbsent() { return true, "no proof of lock was provided" } return false, "" } func (e *AmnesiaEvidence) String() string { return fmt.Sprintf("AmnesiaEvidence{ %v, polc: %v }", e.PotentialAmnesiaEvidence, e.Polc) } func (e *AmnesiaEvidence) ToProto() *tmproto.AmnesiaEvidence { paepb := e.PotentialAmnesiaEvidence.ToProto() polc, err := e.Polc.ToProto() if err != nil { polc, _ = NewEmptyPOLC().ToProto() } return &tmproto.AmnesiaEvidence{ PotentialAmnesiaEvidence: paepb, Polc: polc, } } func ProofOfLockChangeFromProto(pb *tmproto.ProofOfLockChange) (*ProofOfLockChange, error) { if pb == nil { return nil, errors.New("nil proof of lock change") } plc := new(ProofOfLockChange) // check if it is an empty polc if pb.PubKey == nil && pb.Votes == nil { return plc, nil } if pb.Votes == nil { return nil, errors.New("proofOfLockChange: is not absent but has no votes") } vpb := make([]*Vote, len(pb.Votes)) for i, v := range pb.Votes { vi, err := VoteFromProto(v) if err != nil { return nil, err } vpb[i] = vi } if pb.PubKey == nil { return nil, errors.New("proofOfLockChange: is not absent but has nil PubKey") } pk, err := cryptoenc.PubKeyFromProto(*pb.PubKey) if err != nil { return nil, err } plc.PubKey = pk plc.Votes = vpb return plc, plc.ValidateBasic() } func PotentialAmnesiaEvidenceFromProto(pb *tmproto.PotentialAmnesiaEvidence) (*PotentialAmnesiaEvidence, error) { voteA, err := VoteFromProto(pb.GetVoteA()) if err != nil { return nil, err } voteB, err := VoteFromProto(pb.GetVoteB()) if err != nil { return nil, err } tp := PotentialAmnesiaEvidence{ VoteA: voteA, VoteB: voteB, HeightStamp: pb.GetHeightStamp(), Timestamp: pb.Timestamp, } return &tp, tp.ValidateBasic() } func AmnesiaEvidenceFromProto(pb *tmproto.AmnesiaEvidence) (*AmnesiaEvidence, error) { if pb == nil { return nil, errors.New("nil amnesia evidence") } pae, err := PotentialAmnesiaEvidenceFromProto(pb.PotentialAmnesiaEvidence) if err != nil { return nil, fmt.Errorf("decoding to amnesia evidence, err: %w", err) } polc, err := ProofOfLockChangeFromProto(pb.Polc) if err != nil { return nil, fmt.Errorf("decoding to amnesia evidence, err: %w", err) } tp := &AmnesiaEvidence{ PotentialAmnesiaEvidence: pae, Polc: polc, } return tp, tp.ValidateBasic() } //-------------------------------------------------- // EvidenceList is a list of Evidence. Evidences is not a word. type EvidenceList []Evidence // Hash returns the simple merkle root hash of the EvidenceList. func (evl EvidenceList) Hash() []byte { // These allocations are required because Evidence is not of type Bytes, and // golang slices can't be typed cast. This shouldn't be a performance problem since // the Evidence size is capped. evidenceBzs := make([][]byte, len(evl)) for i := 0; i < len(evl); i++ { evidenceBzs[i] = evl[i].Bytes() } return merkle.HashFromByteSlices(evidenceBzs) } func (evl EvidenceList) String() string { s := "" for _, e := range evl { s += fmt.Sprintf("%s\t\t", e) } return s } // Has returns true if the evidence is in the EvidenceList. func (evl EvidenceList) Has(evidence Evidence) bool { for _, ev := range evl { if ev.Equal(evidence) { return true } } return false } //-------------------------------------------- MOCKING -------------------------------------- // unstable - use only for testing // assumes the round to be 0 and the validator index to be 0 func NewMockDuplicateVoteEvidence(height int64, time time.Time, chainID string) *DuplicateVoteEvidence { val := NewMockPV() return NewMockDuplicateVoteEvidenceWithValidator(height, time, val, chainID) } func NewMockDuplicateVoteEvidenceWithValidator(height int64, time time.Time, pv PrivValidator, chainID string) *DuplicateVoteEvidence { pubKey, _ := pv.GetPubKey() voteA := makeMockVote(height, 0, 0, pubKey.Address(), randBlockID(), time) vA := voteA.ToProto() _ = pv.SignVote(chainID, vA) voteA.Signature = vA.Signature voteB := makeMockVote(height, 0, 0, pubKey.Address(), randBlockID(), time) vB := voteB.ToProto() _ = pv.SignVote(chainID, vB) voteB.Signature = vB.Signature return NewDuplicateVoteEvidence(voteA, voteB, time) } func makeMockVote(height int64, round, index int32, addr Address, blockID BlockID, time time.Time) *Vote { return &Vote{ Type: tmproto.SignedMsgType(2), Height: height, Round: round, BlockID: blockID, Timestamp: time, ValidatorAddress: addr, ValidatorIndex: index, } } func randBlockID() BlockID { return BlockID{ Hash: tmrand.Bytes(tmhash.Size), PartSetHeader: PartSetHeader{ Total: 1, Hash: tmrand.Bytes(tmhash.Size), }, } } // mock polc - fails validate basic, not stable func NewMockPOLC(height int64, time time.Time, pubKey crypto.PubKey) ProofOfLockChange { voteVal := NewMockPV() pKey, _ := voteVal.GetPubKey() vote := Vote{Type: tmproto.PrecommitType, Height: height, Round: 1, BlockID: BlockID{}, Timestamp: time, ValidatorAddress: pKey.Address(), ValidatorIndex: 1, Signature: []byte{}} v := vote.ToProto() if err := voteVal.SignVote("mock-chain-id", v); err != nil { panic(err) } vote.Signature = v.Signature return ProofOfLockChange{ Votes: []*Vote{&vote}, PubKey: pubKey, } } func maxTime(t1 time.Time, t2 time.Time) time.Time { if t1.After(t2) { return t1 } return t2 }