Limit simulation gas (cosmos#674)

* Limit simulation gas

* Put parameters on separate lines

app/ante.go

@@ -8,22 +8,27 @@ import (
 	channelkeeper "github.com/cosmos/cosmos-sdk/x/ibc/core/04-channel/keeper"
 	ibcante "github.com/cosmos/cosmos-sdk/x/ibc/core/ante"
 
+	wasmTypes "github.com/CosmWasm/wasmd/x/wasm/types"
+
 	wasmkeeper "github.com/CosmWasm/wasmd/x/wasm/keeper"
 )
 
 // NewAnteHandler returns an AnteHandler that checks and increments sequence
 // numbers, checks signatures & account numbers, and deducts fees from the first
 // signer.
 func NewAnteHandler(
-	ak ante.AccountKeeper, bankKeeper types.BankKeeper,
+	ak ante.AccountKeeper,
+	bankKeeper types.BankKeeper,
 	sigGasConsumer ante.SignatureVerificationGasConsumer,
 	signModeHandler signing.SignModeHandler,
 	txCounterStoreKey sdk.StoreKey,
 	channelKeeper channelkeeper.Keeper,
+	wasmConfig wasmTypes.WasmConfig,
 ) sdk.AnteHandler {
 	// copied sdk https://github.com/cosmos/cosmos-sdk/blob/v0.42.9/x/auth/ante/ante.go
 	return sdk.ChainAnteDecorators(
-		ante.NewSetUpContextDecorator(), // outermost AnteDecorator. SetUpContext must be called first
+		ante.NewSetUpContextDecorator(),                                          // outermost AnteDecorator. SetUpContext must be called first
+		wasmkeeper.NewLimitSimulationGasDecorator(wasmConfig.SimulationGasLimit), // after setup context to enforce limits early
 		wasmkeeper.NewCountTXDecorator(txCounterStoreKey),
 		ante.NewRejectExtensionOptionsDecorator(),
 		ante.NewMempoolFeeDecorator(),

app/app.go

@@ -1,6 +1,7 @@
 package app
 
 import (
+	"fmt"
 	"io"
 	"net/http"
 	"os"
@@ -235,9 +236,19 @@ type WasmApp struct {
 }
 
 // NewWasmApp returns a reference to an initialized WasmApp.
-func NewWasmApp(logger log.Logger, db dbm.DB, traceStore io.Writer, loadLatest bool,
-	skipUpgradeHeights map[int64]bool, homePath string, invCheckPeriod uint, enabledProposals []wasm.ProposalType,
-	appOpts servertypes.AppOptions, wasmOpts []wasm.Option, baseAppOptions ...func(*baseapp.BaseApp)) *WasmApp {
+func NewWasmApp(
+	logger log.Logger,
+	db dbm.DB,
+	traceStore io.Writer,
+	loadLatest bool,
+	skipUpgradeHeights map[int64]bool,
+	homePath string,
+	invCheckPeriod uint,
+	enabledProposals []wasm.ProposalType,
+	appOpts servertypes.AppOptions,
+	wasmOpts []wasm.Option,
+	baseAppOptions ...func(*baseapp.BaseApp),
+) *WasmApp {
 
 	encodingConfig := MakeEncodingConfig()
 	appCodec, legacyAmino := encodingConfig.Marshaler, encodingConfig.Amino
@@ -346,7 +357,7 @@ func NewWasmApp(logger log.Logger, db dbm.DB, traceStore io.Writer, loadLatest b
 	wasmDir := filepath.Join(homePath, "wasm")
 	wasmConfig, err := wasm.ReadWasmConfig(appOpts)
 	if err != nil {
-		panic("error while reading wasm config: " + err.Error())
+		panic(fmt.Sprintf("error while reading wasm config: %s", err))
 	}
 
 	// The last arguments can contain custom message handlers, and custom query handlers,
@@ -485,6 +496,7 @@ func NewWasmApp(logger log.Logger, db dbm.DB, traceStore io.Writer, loadLatest b
 		NewAnteHandler(
 			app.accountKeeper, app.bankKeeper, ante.DefaultSigVerificationGasConsumer,
 			encodingConfig.TxConfig.SignModeHandler(), keys[wasm.StoreKey], app.ibcKeeper.ChannelKeeper,
+			wasmConfig,
 		),
 	)
 	app.SetEndBlocker(app.EndBlocker)

x/wasm/keeper/ante.go

@@ -53,3 +53,44 @@ func encodeHeightCounter(height int64, counter uint32) []byte {
 func decodeHeightCounter(bz []byte) (int64, uint32) {
 	return int64(sdk.BigEndianToUint64(bz[0:8])), binary.BigEndian.Uint32(bz[8:])
 }
+
+// LimitSimulationGasDecorator ante decorator to limit gas in simulation calls
+type LimitSimulationGasDecorator struct {
+	gasLimit *sdk.Gas
+}
+
+// NewLimitSimulationGasDecorator constructor accepts nil value to fallback to block gas limit.
+func NewLimitSimulationGasDecorator(gasLimit *sdk.Gas) *LimitSimulationGasDecorator {
+	if gasLimit != nil && *gasLimit == 0 {
+		panic("gas limit must not be zero")
+	}
+	return &LimitSimulationGasDecorator{gasLimit: gasLimit}
+}
+
+// AnteHandle that limits the maximum gas available in simulations only.
+// A custom max value can be configured and will be applied when set. The value should not
+// exceed the max block gas limit.
+// Different values on nodes are not consensus breaking as they affect only
+// simulations but may have effect on client user experience.
+//
+// When no custom value is set then the max block gas is used as default limit.
+func (d LimitSimulationGasDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (sdk.Context, error) {
+	if !simulate {
+		// Wasm code is not executed in checkTX so that we don't need to limit it further.
+		// Tendermint rejects the TX afterwards when the tx.gas > max block gas.
+		// On deliverTX we rely on the tendermint/sdk mechanics that ensure
+		// tx has gas set and gas < max block gas
+		return next(ctx, tx, simulate)
+	}
+
+	// apply custom node gas limit
+	if d.gasLimit != nil {
+		return next(ctx.WithGasMeter(sdk.NewGasMeter(*d.gasLimit)), tx, simulate)
+	}
+
+	// default to max block gas when set, to be on the safe side
+	if maxGas := ctx.ConsensusParams().GetBlock().MaxGas; maxGas > 0 {
+		return next(ctx.WithGasMeter(sdk.NewGasMeter(sdk.Gas(maxGas))), tx, simulate)
+	}
+	return next(ctx, tx, simulate)
+}

x/wasm/keeper/ante_test.go

@@ -1,9 +1,13 @@
-package keeper
+package keeper_test
 
 import (
 	"testing"
 	"time"
 
+	abci "github.com/tendermint/tendermint/abci/types"
+
+	"github.com/CosmWasm/wasmd/x/wasm/keeper"
+
 	"github.com/cosmos/cosmos-sdk/store"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/stretchr/testify/assert"
@@ -97,7 +101,7 @@ func TestCountTxDecorator(t *testing.T) {
 			var anyTx sdk.Tx
 
 			// when
-			ante := NewCountTXDecorator(keyWasm)
+			ante := keeper.NewCountTXDecorator(keyWasm)
 			_, gotErr := ante.AnteHandle(ctx, anyTx, spec.simulate, spec.nextAssertAnte)
 			if spec.expErr {
 				require.Error(t, gotErr)
@@ -107,3 +111,77 @@ func TestCountTxDecorator(t *testing.T) {
 		})
 	}
 }
+func TestLimitSimulationGasDecorator(t *testing.T) {
+	var (
+		hundred sdk.Gas = 100
+		zero    sdk.Gas = 0
+	)
+	specs := map[string]struct {
+		customLimit *sdk.Gas
+		consumeGas  sdk.Gas
+		maxBlockGas int64
+		simulation  bool
+		expErr      interface{}
+	}{
+		"custom limit set": {
+			customLimit: &hundred,
+			consumeGas:  hundred + 1,
+			maxBlockGas: -1,
+			simulation:  true,
+			expErr:      sdk.ErrorOutOfGas{Descriptor: "testing"},
+		},
+		"block limit set": {
+			maxBlockGas: 100,
+			consumeGas:  hundred + 1,
+			simulation:  true,
+			expErr:      sdk.ErrorOutOfGas{Descriptor: "testing"},
+		},
+		"no limits set": {
+			maxBlockGas: -1,
+			consumeGas:  hundred + 1,
+			simulation:  true,
+		},
+		"both limits set, custom applies": {
+			customLimit: &hundred,
+			consumeGas:  hundred - 1,
+			maxBlockGas: 10,
+			simulation:  true,
+		},
+		"not a simulation": {
+			customLimit: &hundred,
+			consumeGas:  hundred + 1,
+			simulation:  false,
+		},
+		"zero custom limit": {
+			customLimit: &zero,
+			simulation:  true,
+			expErr:      "gas limit must not be zero",
+		},
+	}
+	for name, spec := range specs {
+		t.Run(name, func(t *testing.T) {
+			nextAnte := consumeGasAnteHandler(spec.consumeGas)
+			ctx := sdk.Context{}.
+				WithGasMeter(sdk.NewInfiniteGasMeter()).
+				WithConsensusParams(&abci.ConsensusParams{
+					Block: &abci.BlockParams{MaxGas: spec.maxBlockGas}})
+			// when
+			if spec.expErr != nil {
+				require.PanicsWithValue(t, spec.expErr, func() {
+					ante := keeper.NewLimitSimulationGasDecorator(spec.customLimit)
+					ante.AnteHandle(ctx, nil, spec.simulation, nextAnte)
+				})
+				return
+			}
+			ante := keeper.NewLimitSimulationGasDecorator(spec.customLimit)
+			ante.AnteHandle(ctx, nil, spec.simulation, nextAnte)
+		})
+	}
+}
+
+func consumeGasAnteHandler(gasToConsume sdk.Gas) sdk.AnteHandler {
+	return func(ctx sdk.Context, tx sdk.Tx, simulate bool) (sdk.Context, error) {
+		ctx.GasMeter().ConsumeGas(gasToConsume, "testing")
+		return ctx, nil
+	}
+}

x/wasm/module.go

@@ -33,8 +33,9 @@ var (
 
 // Module init related flags
 const (
-	flagWasmMemoryCacheSize = "wasm.memory_cache_size"
-	flagWasmQueryGasLimit   = "wasm.query_gas_limit"
+	flagWasmMemoryCacheSize    = "wasm.memory_cache_size"
+	flagWasmQueryGasLimit      = "wasm.query_gas_limit"
+	flagWasmSimulationGasLimit = "wasm.simulation_gas_limit"
 )
 
 // AppModuleBasic defines the basic application module used by the wasm module.
@@ -199,6 +200,7 @@ func AddModuleInitFlags(startCmd *cobra.Command) {
 	defaults := DefaultWasmConfig()
 	startCmd.Flags().Uint32(flagWasmMemoryCacheSize, defaults.MemoryCacheSize, "Sets the size in MiB (NOT bytes) of an in-memory cache for Wasm modules. Set to 0 to disable.")
 	startCmd.Flags().Uint64(flagWasmQueryGasLimit, defaults.SmartQueryGasLimit, "Set the max gas that can be spent on executing a query with a Wasm contract")
+	startCmd.Flags().String(flagWasmSimulationGasLimit, "", "Set the max gas that can be spent when executing a simulation TX")
 }
 
 // ReadWasmConfig reads the wasm specifig configuration
@@ -215,6 +217,15 @@ func ReadWasmConfig(opts servertypes.AppOptions) (types.WasmConfig, error) {
 			return cfg, err
 		}
 	}
+	if v := opts.Get(flagWasmSimulationGasLimit); v != nil {
+		if raw, ok := v.(string); ok && raw != "" {
+			limit, err := cast.ToUint64E(v) // non empty string set
+			if err != nil {
+				return cfg, err
+			}
+			cfg.SimulationGasLimit = &limit
+		}
+	}
 	// attach contract debugging to global "trace" flag
 	if v := opts.Get(server.FlagTrace); v != nil {
 		if cfg.ContractDebugMode, err = cast.ToBoolE(v); err != nil {

x/wasm/types/types.go

@@ -12,9 +12,9 @@ import (
 )
 
 const (
-	defaultMemoryCacheSize   uint32 = 100 // in MiB
-	defaultQueryGasLimit     uint64 = 3000000
-	defaultContractDebugMode        = false
+	defaultMemoryCacheSize    uint32 = 100 // in MiB
+	defaultSmartQueryGasLimit uint64 = 3_000_000
+	defaultContractDebugMode         = false
 )
 
 func (m Model) ValidateBasic() error {
@@ -296,6 +296,10 @@ func NewWasmCoins(cosmosCoins sdk.Coins) (wasmCoins []wasmvmtypes.Coin) {
 
 // WasmConfig is the extra config required for wasm
 type WasmConfig struct {
+	// SimulationGasLimit is the max gas to be used in a tx simulation call.
+	// When not set the consensus max block gas is used instead
+	SimulationGasLimit *uint64
+	// SimulationGasLimit is the max gas to be used in a smart query contract call
 	SmartQueryGasLimit uint64
 	// MemoryCacheSize in MiB not bytes
 	MemoryCacheSize uint32
@@ -306,7 +310,7 @@ type WasmConfig struct {
 // DefaultWasmConfig returns the default settings for WasmConfig
 func DefaultWasmConfig() WasmConfig {
 	return WasmConfig{
-		SmartQueryGasLimit: defaultQueryGasLimit,
+		SmartQueryGasLimit: defaultSmartQueryGasLimit,
 		MemoryCacheSize:    defaultMemoryCacheSize,
 		ContractDebugMode:  defaultContractDebugMode,
 	}