Relax Chain ID format requirement for EIP-712 verification

The upstream Eip712SigVerificationDecorator requires the Cosmos Chain ID
to adhere to a format like "evmos_7001-1" which does not work for
Gravity's "gravity-bridge-3" format. This commit adds a EvmChainId value
to the AnteHandler HandlerOptions so that Gravity can override that
check and use its existing Chain ID format.

Chain IDs are difficult to change and cause a lot of issues with IBC
channels once changed. By relaxing this restriction the integration of
EIP-712 is made much simpler.

app/ante/eip712.go

@@ -37,18 +37,23 @@ func init() {
 type Eip712SigVerificationDecorator struct {
 	ak              evmtypes.AccountKeeper
 	signModeHandler authsigning.SignModeHandler
+	evmChainId      string
 }
 
 // NewEip712SigVerificationDecorator creates a new Eip712SigVerificationDecorator
-func NewEip712SigVerificationDecorator(ak evmtypes.AccountKeeper, signModeHandler authsigning.SignModeHandler) Eip712SigVerificationDecorator {
+// Allows an optional EVM Chain ID (e.g. 1 for Ethereum Mainnet). The upstream Evmos repo requires the Cosmos Chain ID
+// to be parseable by a regex but evmChainId removes that restriction by allowing an override.
+func NewEip712SigVerificationDecorator(ak evmtypes.AccountKeeper, signModeHandler authsigning.SignModeHandler, evmChainId string) Eip712SigVerificationDecorator {
 	return Eip712SigVerificationDecorator{
 		ak:              ak,
 		signModeHandler: signModeHandler,
+		evmChainId:      evmChainId,
 	}
 }
 
 // AnteHandle handles validation of EIP712 signed cosmos txs.
 // it is not run on RecheckTx
+// Note that this decorator differs from the upstream repo by removing the chain ID format restriction
 func (svd Eip712SigVerificationDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) {
 	// no need to verify signatures on recheck tx
 	if ctx.IsReCheckTx() {
@@ -116,6 +121,18 @@ func (svd Eip712SigVerificationDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx,
 		accNum = acc.GetAccountNumber()
 	}
 
+	// There are two ChainIDs to verify, the Cosmos string and the EVM number. First try the EVM override value,
+	// then try to parse if no override provided
+	var evmChainID string = svd.evmChainId
+	if evmChainID == "" {
+		cId, err := ethermint.ParseChainID(chainID)
+
+		if err != nil {
+			return ctx, sdkerrors.Wrapf(err, "failed to parse chainID: %s", chainID)
+		}
+		evmChainID = cId.String()
+	}
+
 	signerData := authsigning.SignerData{
 		ChainID:       chainID,
 		AccountNumber: accNum,
@@ -126,8 +143,8 @@ func (svd Eip712SigVerificationDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx,
 		return next(ctx, tx, simulate)
 	}
 
-	if err := VerifySignature(pubKey, signerData, sig.Data, svd.signModeHandler, authSignTx); err != nil {
-		errMsg := fmt.Errorf("signature verification failed; please verify account number (%d) and chain-id (%s): %w", accNum, chainID, err)
+	if err := VerifySignature(pubKey, signerData, sig.Data, svd.signModeHandler, authSignTx, evmChainID); err != nil {
+		errMsg := fmt.Errorf("signature verification failed; please verify account number (%d) and chain-id (%s) and evm-chain-id (%s): %w", accNum, chainID, evmChainID, err)
 		return ctx, sdkerrors.Wrap(sdkerrors.ErrUnauthorized, errMsg.Error())
 	}
 
@@ -136,12 +153,15 @@ func (svd Eip712SigVerificationDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx,
 
 // VerifySignature verifies a transaction signature contained in SignatureData abstracting over different signing modes
 // and single vs multi-signatures.
+// Note that this decorator differs from the upstream repo by removing the chain ID format restriction, so signerData.ChainID is not parsed.
+// The evmChainID parameter is used instead of Cosmos ChainID parsing
 func VerifySignature(
 	pubKey cryptotypes.PubKey,
 	signerData authsigning.SignerData,
 	sigData signing.SignatureData,
 	_ authsigning.SignModeHandler,
 	tx authsigning.Tx,
+	evmChainID string,
 ) error {
 	switch data := sigData.(type) {
 	case *signing.SingleSignatureData:
@@ -174,11 +194,6 @@ func VerifySignature(
 			msgs, tx.GetMemo(),
 		)
 
-		signerChainID, err := ethermint.ParseChainID(signerData.ChainID)
-		if err != nil {
-			return sdkerrors.Wrapf(err, "failed to parse chainID: %s", signerData.ChainID)
-		}
-
 		txWithExtensions, ok := tx.(authante.HasExtensionOptionsTx)
 		if !ok {
 			return sdkerrors.Wrap(sdkerrors.ErrUnknownExtensionOptions, "tx doesnt contain any extensions")
@@ -199,8 +214,9 @@ func VerifySignature(
 			return sdkerrors.Wrap(sdkerrors.ErrInvalidChainID, "unknown extension option")
 		}
 
-		if extOpt.TypedDataChainID != signerChainID.Uint64() {
-			return sdkerrors.Wrap(sdkerrors.ErrInvalidChainID, "invalid chainID")
+		typedDataChainID := fmt.Sprint(extOpt.TypedDataChainID)
+		if typedDataChainID != evmChainID {
+			return sdkerrors.Wrapf(sdkerrors.ErrInvalidChainID, "eip-712 domain chainID: (%s) != (%s)", typedDataChainID, evmChainID)
 		}
 
 		if len(extOpt.FeePayer) == 0 {

app/ante/handler_options.go

@@ -16,6 +16,8 @@ import (
 
 // HandlerOptions extend the SDK's AnteHandler options by requiring the IBC
 // channel keeper, EVM Keeper and Fee Market Keeper.
+// Note that this struct differs from the upstream repo by adding the optional EvmChainID override used in
+// EIP-712 signature verification instead of parsing the Cosmos Chain ID
 type HandlerOptions struct {
 	AccountKeeper   evmtypes.AccountKeeper
 	BankKeeper      evmtypes.BankKeeper
@@ -26,6 +28,7 @@ type HandlerOptions struct {
 	SignModeHandler authsigning.SignModeHandler
 	SigGasConsumer  func(meter sdk.GasMeter, sig signing.SignatureV2, params authtypes.Params) error
 	MaxTxGasWanted  uint64
+	EvmChainID      string
 }
 
 func (options HandlerOptions) validate() error {
@@ -104,7 +107,7 @@ func newCosmosAnteHandlerEip712(options HandlerOptions) sdk.AnteHandler {
 		ante.NewValidateSigCountDecorator(options.AccountKeeper),
 		ante.NewSigGasConsumeDecorator(options.AccountKeeper, options.SigGasConsumer),
 		// Note: signature verification uses EIP instead of the cosmos signature validator
-		NewEip712SigVerificationDecorator(options.AccountKeeper, options.SignModeHandler),
+		NewEip712SigVerificationDecorator(options.AccountKeeper, options.SignModeHandler, options.EvmChainID),
 		ante.NewIncrementSequenceDecorator(options.AccountKeeper),
 		ibcante.NewAnteDecorator(options.IBCKeeper),
 		NewGasWantedDecorator(options.EvmKeeper, options.FeeMarketKeeper),