fix!: add GovVoteDecorator (#2912)

* add GovVoteDecorator

* add changelog entries

* fix linter

* add unit test

* fix linter

* Update ante/gov_vote_ante.go

Co-authored-by: MSalopek <matija.salopek994@gmail.com>

---------

Co-authored-by: MSalopek <matija.salopek994@gmail.com>

.changelog/unreleased/bug-fixes/2912-vote-spam.md

@@ -0,0 +1,2 @@
+- Add ante handler that only allows `MsgVote` messages from accounts with at least
+  1 atom staked. ([\#2912](https://github.com/cosmos/gaia/pull/2912))

.changelog/unreleased/state-breaking/2912-vote-spam.md

@@ -0,0 +1,2 @@
+- Add ante handler that only allows `MsgVote` messages from accounts with at least
+  1 atom staked. ([\#2912](https://github.com/cosmos/gaia/pull/2912))

ante/ante.go

@@ -61,6 +61,7 @@ func NewAnteHandler(opts HandlerOptions) (sdk.AnteHandler, error) {
 		ante.NewTxTimeoutHeightDecorator(),
 		ante.NewValidateMemoDecorator(opts.AccountKeeper),
 		ante.NewConsumeGasForTxSizeDecorator(opts.AccountKeeper),
+		NewGovVoteDecorator(opts.Codec, opts.StakingKeeper),
 		gaiafeeante.NewFeeDecorator(opts.GlobalFeeSubspace, opts.StakingKeeper),
 		ante.NewDeductFeeDecorator(opts.AccountKeeper, opts.BankKeeper, opts.FeegrantKeeper, opts.TxFeeChecker),
 		ante.NewSetPubKeyDecorator(opts.AccountKeeper), // SetPubKeyDecorator must be called before all signature verification decorators

ante/gov_vote_ante.go

@@ -0,0 +1,116 @@
+package ante
+
+import (
+	errorsmod "cosmossdk.io/errors"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/authz"
+	govv1beta1 "github.com/cosmos/cosmos-sdk/x/gov/types/v1beta1"
+	stakingkeeper "github.com/cosmos/cosmos-sdk/x/staking/keeper"
+	stakingtypes "github.com/cosmos/cosmos-sdk/x/staking/types"
+
+	gaiaerrors "github.com/cosmos/gaia/v15/types/errors"
+)
+
+var (
+	minStakedTokens       = sdk.NewDec(1000000) // 1_000_000 uatom (or 1 atom)
+	maxDelegationsChecked = 100                 // number of delegation to check for the minStakedTokens
+)
+
+type GovVoteDecorator struct {
+	stakingKeeper *stakingkeeper.Keeper
+	cdc           codec.BinaryCodec
+}
+
+func NewGovVoteDecorator(cdc codec.BinaryCodec, stakingKeeper *stakingkeeper.Keeper) GovVoteDecorator {
+	return GovVoteDecorator{
+		stakingKeeper: stakingKeeper,
+		cdc:           cdc,
+	}
+}
+
+func (g GovVoteDecorator) AnteHandle(
+	ctx sdk.Context, tx sdk.Tx,
+	simulate bool, next sdk.AnteHandler,
+) (newCtx sdk.Context, err error) {
+	// do not run check during simulations
+	if simulate {
+		return next(ctx, tx, simulate)
+	}
+
+	msgs := tx.GetMsgs()
+	if err = g.ValidateVoteMsgs(ctx, msgs); err != nil {
+		return ctx, err
+	}
+
+	return next(ctx, tx, simulate)
+}
+
+// ValidateVoteMsgs checks if a voter has enough stake to vote
+func (g GovVoteDecorator) ValidateVoteMsgs(ctx sdk.Context, msgs []sdk.Msg) error {
+	validMsg := func(m sdk.Msg) error {
+		if msg, ok := m.(*govv1beta1.MsgVote); ok {
+			accAddr, err := sdk.AccAddressFromBech32(msg.Voter)
+			if err != nil {
+				return err
+			}
+			enoughStake := false
+			delegationCount := 0
+			stakedTokens := sdk.NewDec(0)
+			g.stakingKeeper.IterateDelegatorDelegations(ctx, accAddr, func(delegation stakingtypes.Delegation) bool {
+				validatorAddr, err := sdk.ValAddressFromBech32(delegation.ValidatorAddress)
+				if err != nil {
+					panic(err) // shouldn't happen
+				}
+				validator, found := g.stakingKeeper.GetValidator(ctx, validatorAddr)
+				if found {
+					shares := delegation.Shares
+					tokens := validator.TokensFromSharesTruncated(shares)
+					stakedTokens = stakedTokens.Add(tokens)
+					if stakedTokens.GTE(minStakedTokens) {
+						enoughStake = true
+						return true // break the iteration
+					}
+				}
+				delegationCount++
+				// break the iteration if maxDelegationsChecked were already checked
+				return delegationCount >= maxDelegationsChecked
+			})
+			if !enoughStake {
+				return errorsmod.Wrapf(gaiaerrors.ErrInsufficientStake, "insufficient stake for voting - min required %v", minStakedTokens)
+			}
+		}
+
+		return nil
+	}
+
+	validAuthz := func(execMsg *authz.MsgExec) error {
+		for _, v := range execMsg.Msgs {
+			var innerMsg sdk.Msg
+			if err := g.cdc.UnpackAny(v, &innerMsg); err != nil {
+				return errorsmod.Wrap(gaiaerrors.ErrUnauthorized, "cannot unmarshal authz exec msgs")
+			}
+			if err := validMsg(innerMsg); err != nil {
+				return err
+			}
+		}
+
+		return nil
+	}
+
+	for _, m := range msgs {
+		if msg, ok := m.(*authz.MsgExec); ok {
+			if err := validAuthz(msg); err != nil {
+				return err
+			}
+			continue
+		}
+
+		// validate normal msgs
+		if err := validMsg(m); err != nil {
+			return err
+		}
+	}
+	return nil
+}

ante/gov_vote_ante_test.go

@@ -0,0 +1,123 @@
+package ante_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	tmproto "github.com/cometbft/cometbft/proto/tendermint/types"
+
+	"cosmossdk.io/math"
+
+	"github.com/cosmos/cosmos-sdk/crypto/keys/ed25519"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	govv1beta1 "github.com/cosmos/cosmos-sdk/x/gov/types/v1beta1"
+	stakingtypes "github.com/cosmos/cosmos-sdk/x/staking/types"
+
+	"github.com/cosmos/gaia/v15/ante"
+	"github.com/cosmos/gaia/v15/app/helpers"
+)
+
+func TestVoteSpamDecorator(t *testing.T) {
+	gaiaApp := helpers.Setup(t)
+	ctx := gaiaApp.NewUncachedContext(true, tmproto.Header{})
+	decorator := ante.NewGovVoteDecorator(gaiaApp.AppCodec(), gaiaApp.StakingKeeper)
+	stakingKeeper := gaiaApp.StakingKeeper
+
+	// Get validator
+	valAddr1 := stakingKeeper.GetAllValidators(ctx)[0].GetOperator()
+
+	// Create one more validator
+	pk := ed25519.GenPrivKeyFromSecret([]byte{uint8(13)}).PubKey()
+	validator2, err := stakingtypes.NewValidator(
+		sdk.ValAddress(pk.Address()),
+		pk,
+		stakingtypes.Description{},
+	)
+	valAddr2 := validator2.GetOperator()
+	require.NoError(t, err)
+	// Make sure the validator is bonded so it's not removed on Undelegate
+	validator2.Status = stakingtypes.Bonded
+	stakingKeeper.SetValidator(ctx, validator2)
+	err = stakingKeeper.SetValidatorByConsAddr(ctx, validator2)
+	require.NoError(t, err)
+	stakingKeeper.SetNewValidatorByPowerIndex(ctx, validator2)
+	err = stakingKeeper.Hooks().AfterValidatorCreated(ctx, validator2.GetOperator())
+	require.NoError(t, err)
+
+	// Get delegator (this account was created during setup)
+	addr := gaiaApp.AccountKeeper.GetAccountAddressByID(ctx, 0)
+	delegator, err := sdk.AccAddressFromBech32(addr)
+	require.NoError(t, err)
+
+	tests := []struct {
+		name       string
+		bondAmt    math.Int
+		validators []sdk.ValAddress
+		expectPass bool
+	}{
+		{
+			name:       "delegate 0.1 atom",
+			bondAmt:    sdk.NewInt(100000),
+			validators: []sdk.ValAddress{valAddr1},
+			expectPass: false,
+		},
+		{
+			name:       "delegate 1 atom",
+			bondAmt:    sdk.NewInt(1000000),
+			validators: []sdk.ValAddress{valAddr1},
+			expectPass: true,
+		},
+		{
+			name:       "delegate 1 atom to two validators",
+			bondAmt:    sdk.NewInt(1000000),
+			validators: []sdk.ValAddress{valAddr1, valAddr2},
+			expectPass: true,
+		},
+		{
+			name:       "delegate 0.9 atom to two validators",
+			bondAmt:    sdk.NewInt(900000),
+			validators: []sdk.ValAddress{valAddr1, valAddr2},
+			expectPass: false,
+		},
+		{
+			name:       "delegate 10 atom",
+			bondAmt:    sdk.NewInt(10000000),
+			validators: []sdk.ValAddress{valAddr1},
+			expectPass: true,
+		},
+	}
+
+	for _, tc := range tests {
+		// Unbond all tokens for this delegator
+		delegations := stakingKeeper.GetAllDelegatorDelegations(ctx, delegator)
+		for _, del := range delegations {
+			_, err := stakingKeeper.Undelegate(ctx, delegator, del.GetValidatorAddr(), del.GetShares())
+			require.NoError(t, err)
+		}
+
+		// Delegate tokens
+		amt := tc.bondAmt.Quo(sdk.NewInt(int64(len(tc.validators))))
+		for _, valAddr := range tc.validators {
+			val, found := stakingKeeper.GetValidator(ctx, valAddr)
+			require.True(t, found)
+			_, err := stakingKeeper.Delegate(ctx, delegator, amt, stakingtypes.Unbonded, val, true)
+			require.NoError(t, err)
+		}
+
+		// Create vote message
+		msg := govv1beta1.NewMsgVote(
+			delegator,
+			0,
+			govv1beta1.OptionYes,
+		)
+
+		// Validate vote message
+		err := decorator.ValidateVoteMsgs(ctx, []sdk.Msg{msg})
+		if tc.expectPass {
+			require.NoError(t, err, "expected %v to pass", tc.name)
+		} else {
+			require.Error(t, err, "expected %v to fail", tc.name)
+		}
+	}
+}

types/errors/errors.go

@@ -31,4 +31,7 @@ var (
 
 	// ErrNotFound defines an error when requested entity doesn't exist in the state.
 	ErrNotFound = errorsmod.Register(codespace, 8, "not found")
+
+	// ErrInsufficientStake is used when the account has insufficient staked tokens.
+	ErrInsufficientStake = errorsmod.Register(codespace, 9, "insufficient stake")
 )