Ante Handler: Nested Evm Messages within Authz (#1472)

* Authz Nested Evm Messages

* Update comments

app/ante.go

@@ -104,6 +104,7 @@ func NewAnteHandlerAndDepGenerator(options HandlerOptions) (sdk.AnteHandler, sdk
 		sdk.CustomDepWrappedAnteDecorator(sequentialVerifyDecorator, depdecorators.SignerDepDecorator{ReadOnly: true}),
 		sdk.CustomDepWrappedAnteDecorator(ante.NewIncrementSequenceDecorator(options.AccountKeeper), depdecorators.SignerDepDecorator{ReadOnly: false}),
 		sdk.DefaultWrappedAnteDecorator(evmante.NewEVMAddressDecorator(options.EVMKeeper, options.EVMKeeper.AccountKeeper())),
+		sdk.DefaultWrappedAnteDecorator(antedecorators.NewAuthzNestedMessageDecorator()),
 		sdk.DefaultWrappedAnteDecorator(ibcante.NewAnteDecorator(options.IBCKeeper)),
 		sdk.DefaultWrappedAnteDecorator(dex.NewTickSizeMultipleDecorator(*options.DexKeeper)),
 		dex.NewCheckDexGasDecorator(*options.DexKeeper, options.CheckTxMemState),

app/antedecorators/authz_nested_message.go

@@ -0,0 +1,63 @@
+package antedecorators
+
+import (
+	"errors"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/authz"
+	evmtypes "github.com/sei-protocol/sei-chain/x/evm/types"
+)
+
+type AuthzNestedMessageDecorator struct{}
+
+func NewAuthzNestedMessageDecorator() AuthzNestedMessageDecorator {
+	return AuthzNestedMessageDecorator{}
+}
+
+func (ad AuthzNestedMessageDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) {
+	for _, msg := range tx.GetMsgs() {
+		switch m := msg.(type) {
+		case *authz.MsgExec:
+			// find nested evm messages
+			containsEvm, err := ad.CheckAuthzContainsEvm(ctx, m)
+			if err != nil {
+				return ctx, err
+			}
+			if containsEvm {
+				return ctx, errors.New("permission denied, authz tx contains evm message")
+			}
+		default:
+			continue
+		}
+	}
+
+	return next(ctx, tx, simulate)
+}
+
+func (ad AuthzNestedMessageDecorator) CheckAuthzContainsEvm(ctx sdk.Context, authzMsg *authz.MsgExec) (bool, error) {
+	msgs, err := authzMsg.GetMessages()
+	if err != nil {
+		return false, err
+	}
+	for _, msg := range msgs {
+		// check if message type is authz exec or evm
+		switch m := msg.(type) {
+		case *evmtypes.MsgEVMTransaction:
+			return true, nil
+		case *authz.MsgExec:
+			// find nested to check for evm
+			valid, err := ad.CheckAuthzContainsEvm(ctx, m)
+
+			if err != nil {
+				return false, err
+			}
+
+			if valid {
+				return true, nil
+			}
+		default:
+			continue
+		}
+	}
+	return false, nil
+}

app/antedecorators/authz_nested_message_test.go

@@ -0,0 +1,58 @@
+package antedecorators_test
+
+import (
+	"testing"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/authz"
+	banktypes "github.com/cosmos/cosmos-sdk/x/bank/types"
+	"github.com/sei-protocol/sei-chain/app/antedecorators"
+	evmtypes "github.com/sei-protocol/sei-chain/x/evm/types"
+	"github.com/stretchr/testify/require"
+	"github.com/tendermint/tendermint/crypto/secp256k1"
+	tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
+)
+
+func TestAuthzNestedEvmMessage(t *testing.T) {
+	priv1 := secp256k1.GenPrivKey()
+	addr1 := sdk.AccAddress(priv1.PubKey().Address())
+	output = ""
+	anteDecorators := []sdk.AnteFullDecorator{
+		sdk.DefaultWrappedAnteDecorator(antedecorators.NewAuthzNestedMessageDecorator()),
+	}
+	ctx := sdk.NewContext(nil, tmproto.Header{}, false, nil)
+	chainedHandler, _ := sdk.ChainAnteDecorators(anteDecorators...)
+
+	nestedEvmMessage := authz.NewMsgExec(addr1, []sdk.Msg{&evmtypes.MsgEVMTransaction{}})
+	// test with nested evm message
+	_, err := chainedHandler(
+		ctx.WithPriority(0),
+		FakeTx{
+			FakeMsgs: []sdk.Msg{&nestedEvmMessage},
+		},
+		false,
+	)
+	require.NotNil(t, err)
+
+	// Multiple nested layers to evm message
+	doubleNestedEvmMessage := authz.NewMsgExec(addr1, []sdk.Msg{&nestedEvmMessage})
+	_, err = chainedHandler(
+		ctx.WithPriority(0),
+		FakeTx{
+			FakeMsgs: []sdk.Msg{&doubleNestedEvmMessage},
+		},
+		false,
+	)
+	require.NotNil(t, err)
+
+	// No error
+	nestedMessage := authz.NewMsgExec(addr1, []sdk.Msg{&banktypes.MsgSend{}})
+	_, err = chainedHandler(
+		ctx.WithPriority(0),
+		FakeTx{
+			FakeMsgs: []sdk.Msg{&nestedMessage},
+		},
+		false,
+	)
+	require.Nil(t, err)
+}