From d7da045fc403e3f3cf9a564feb71f16c914d65ee Mon Sep 17 00:00:00 2001
From: hello-bwhour <juvemeen.xio@gmail.com>
Date: Wed, 16 Jun 2021 01:39:41 +0800
Subject: [PATCH] ante: check that sender is a EOA (#125)

* ante: check that sender is a EOA

* fix: GetCodeSize handles nil case and comments

* docs: add TODO comment

* fix: use EmptyCodeHash check

* lint: evmtypes instead of types

* lint: fix suite error

* test: set code to act not as EOA

* undo comment on GetCodeSize

* keeper: fix input checks

* Apply suggestions from code review

Co-authored-by: Akash Khosla <me@akashkhosla.com>
Co-authored-by: Federico Kunze <31522760+fedekunze@users.noreply.github.com>
---
 app/ante/eth.go         | 15 +++++++++++++--
 app/ante/eth_test.go    | 15 ++++++++++++++-
 app/ante/utils_test.go  |  1 +
 x/evm/keeper/statedb.go |  9 +++++++--
 4 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/app/ante/eth.go b/app/ante/eth.go
index 496fed91..d0eeb95e 100644
--- a/app/ante/eth.go
+++ b/app/ante/eth.go
@@ -28,6 +28,7 @@ type EVMKeeper interface {
 	WithContext(ctx sdk.Context)
 	ResetRefundTransient(ctx sdk.Context)
 	NewEVM(msg core.Message, config *params.ChainConfig) *vm.EVM
+	GetCodeHash(addr common.Address) common.Hash
 }
 
 // EthSigVerificationDecorator validates an ethereum signatures
@@ -126,7 +127,7 @@ func (avd EthAccountVerificationDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx
 	// get and set account must be called with an infinite gas meter in order to prevent
 	// additional gas from being deducted.
 	infCtx := ctx.WithGasMeter(sdk.NewInfiniteGasMeter())
-
+	avd.evmKeeper.WithContext(infCtx)
 	evmDenom := avd.evmKeeper.GetParams(infCtx).EvmDenom
 
 	for i, msg := range tx.GetMsgs() {
@@ -147,6 +148,14 @@ func (avd EthAccountVerificationDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx
 			)
 		}
 
+		// check whether the sender address is EOA
+		fromAddr := common.BytesToAddress(from)
+		codeHash := avd.evmKeeper.GetCodeHash(fromAddr)
+		if codeHash != common.BytesToHash(evmtypes.EmptyCodeHash) {
+			return ctx, stacktrace.Propagate(sdkerrors.Wrapf(sdkerrors.ErrInvalidType,
+				"the sender is not EOA: address <%v>, codeHash <%s>", fromAddr, codeHash), "")
+		}
+
 		acc := avd.ak.GetAccount(infCtx, from)
 		if acc == nil {
 			acc = avd.ak.NewAccountWithAddress(infCtx, from)
@@ -164,8 +173,10 @@ func (avd EthAccountVerificationDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx
 				"sender should have had enough funds to pay for tx cost = fee + amount (%s = %s + amount)", msgEthTx.Cost(), msgEthTx.Fee(),
 			)
 		}
-	}
 
+	}
+	// recover  the original gas meter
+	avd.evmKeeper.WithContext(ctx)
 	return next(ctx, tx, simulate)
 }
 
diff --git a/app/ante/eth_test.go b/app/ante/eth_test.go
index e0e6446e..f342431c 100644
--- a/app/ante/eth_test.go
+++ b/app/ante/eth_test.go
@@ -86,10 +86,23 @@ func (suite AnteTestSuite) TestNewEthAccountVerificationDecorator() {
 			true,
 			false,
 		},
+		{
+			"sender not EOA",
+			tx,
+			func() {
+				// set not as an EOA
+				suite.app.EvmKeeper.SetCode(addr, []byte("1"))
+			},
+			true,
+			false,
+		},
 		{
 			"not enough balance to cover tx cost",
 			tx,
-			func() {},
+			func() {
+				// reset back to EOA
+				suite.app.EvmKeeper.SetCode(addr, nil)
+			},
 			true,
 			false,
 		},
diff --git a/app/ante/utils_test.go b/app/ante/utils_test.go
index 620aa56e..cbc5e753 100644
--- a/app/ante/utils_test.go
+++ b/app/ante/utils_test.go
@@ -86,6 +86,7 @@ func (suite *AnteTestSuite) CreateTestTx(
 	suite.Require().NoError(err)
 
 	err = builder.SetMsgs(msg)
+	suite.Require().NoError(err)
 	fees := sdk.NewCoins(sdk.NewCoin(evmtypes.DefaultEVMDenom, sdk.NewIntFromBigInt(msg.Fee())))
 	builder.SetFeeAmount(fees)
 	builder.SetGasLimit(msg.GetGas())
diff --git a/x/evm/keeper/statedb.go b/x/evm/keeper/statedb.go
index a4c157f0..2ea7f552 100644
--- a/x/evm/keeper/statedb.go
+++ b/x/evm/keeper/statedb.go
@@ -228,6 +228,9 @@ func (k *Keeper) GetCode(addr common.Address) []byte {
 
 // SetCode calls CommitStateDB.SetCode using the passed in context
 func (k *Keeper) SetCode(addr common.Address, code []byte) {
+	if bytes.Equal(code, types.EmptyCodeHash) {
+		k.Logger(k.ctx).Debug("passed in EmptyCodeHash, but expected empty code")
+	}
 	hash := crypto.Keccak256Hash(code)
 
 	// update account code hash
@@ -269,9 +272,11 @@ func (k *Keeper) SetCode(addr common.Address, code []byte) {
 	)
 }
 
-// GetCodeSize returns the code hash stored in the address account.
+// GetCodeSize returns the size of the contract code associated with this object,
+// or zero if none.
 func (k *Keeper) GetCodeSize(addr common.Address) int {
-	return len(k.GetCode(addr))
+	code := k.GetCode(addr)
+	return len(code)
 }
 
 // ----------------------------------------------------------------------------