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Add safety check: restriction fn in bank module for mint perms (#50)
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mattverse authored and sunnya97 committed Jan 24, 2022
1 parent b87def6 commit b47e802
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Showing 4 changed files with 113 additions and 10 deletions.
1 change: 1 addition & 0 deletions CHANGELOG.md
Original file line number Diff line number Diff line change
Expand Up @@ -354,6 +354,7 @@ Security Release. No breaking changes related to 0.44.x.
* [\#9428](https://github.com/cosmos/cosmos-sdk/pull/9428) Optimize bank InitGenesis. Added `k.initBalances`.
* [\#9429](https://github.com/cosmos/cosmos-sdk/pull/9429) Add `cosmos_sdk_version` to node_info
* [\#9541](https://github.com/cosmos/cosmos-sdk/pull/9541) Bump tendermint dependency to v0.34.11.
* (x/bank) [\#10771](https://github.com/cosmos/cosmos-sdk/pull/10771) Add safety check on bank module perms to allow module-specific mint restrictions (e.g. only minting a certain denom).

### Bug Fixes

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49 changes: 39 additions & 10 deletions x/bank/keeper/keeper.go
Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@ var _ Keeper = (*BaseKeeper)(nil)
// between accounts.
type Keeper interface {
SendKeeper
WithMintCoinsRestriction(BankMintingRestrictionFn) BaseKeeper

InitGenesis(sdk.Context, *types.GenesisState)
ExportGenesis(sdk.Context) *types.GenesisState
Expand Down Expand Up @@ -53,12 +54,15 @@ type Keeper interface {
type BaseKeeper struct {
BaseSendKeeper

ak types.AccountKeeper
cdc codec.BinaryCodec
storeKey sdk.StoreKey
paramSpace paramtypes.Subspace
ak types.AccountKeeper
cdc codec.BinaryCodec
storeKey sdk.StoreKey
paramSpace paramtypes.Subspace
mintCoinsRestrictionFn BankMintingRestrictionFn
}

type BankMintingRestrictionFn func(ctx sdk.Context, coins sdk.Coins) error

// GetPaginatedTotalSupply queries for the supply, ignoring 0 coins, with a given pagination
func (k BaseKeeper) GetPaginatedTotalSupply(ctx sdk.Context, pagination *query.PageRequest) (sdk.Coins, *query.PageResponse, error) {
store := ctx.KVStore(k.storeKey)
Expand Down Expand Up @@ -105,12 +109,32 @@ func NewBaseKeeper(
}

return BaseKeeper{
BaseSendKeeper: NewBaseSendKeeper(cdc, storeKey, ak, paramSpace, blockedAddrs),
ak: ak,
cdc: cdc,
storeKey: storeKey,
paramSpace: paramSpace,
BaseSendKeeper: NewBaseSendKeeper(cdc, storeKey, ak, paramSpace, blockedAddrs),
ak: ak,
cdc: cdc,
storeKey: storeKey,
paramSpace: paramSpace,
mintCoinsRestrictionFn: func(ctx sdk.Context, coins sdk.Coins) error { return nil },
}
}

// WithMintCoinsRestriction restricts the bank Keeper used within a specific module to
// have restricted permissions on minting speicified denoms.
func (k BaseKeeper) WithMintCoinsRestriction(NewRestrictionFn BankMintingRestrictionFn) BaseKeeper {
// this allows nesting restriction functions
oldRestrictionFn := k.mintCoinsRestrictionFn
k.mintCoinsRestrictionFn = func(ctx sdk.Context, coins sdk.Coins) error {
err := NewRestrictionFn(ctx, coins)
if err != nil {
return err
}
err = oldRestrictionFn(ctx, coins)
if err != nil {
return err
}
return nil
}
return k
}

// DelegateCoins performs delegation by deducting amt coins from an account with
Expand Down Expand Up @@ -399,6 +423,11 @@ func (k BaseKeeper) UndelegateCoinsFromModuleToAccount(
// MintCoins creates new coins from thin air and adds it to the module account.
// It will panic if the module account does not exist or is unauthorized.
func (k BaseKeeper) MintCoins(ctx sdk.Context, moduleName string, amounts sdk.Coins) error {
err := k.mintCoinsRestrictionFn(ctx, amounts)
if err != nil {
ctx.Logger().Error(fmt.Sprintf("Module %s attempted minting coins %s it did not have permission for with error %v", moduleName, amounts, err))
return err
}
acc := k.ak.GetModuleAccount(ctx, moduleName)
if acc == nil {
panic(sdkerrors.Wrapf(sdkerrors.ErrUnknownAddress, "module account %s does not exist", moduleName))
Expand All @@ -408,7 +437,7 @@ func (k BaseKeeper) MintCoins(ctx sdk.Context, moduleName string, amounts sdk.Co
panic(sdkerrors.Wrapf(sdkerrors.ErrUnauthorized, "module account %s does not have permissions to mint tokens", moduleName))
}

err := k.addCoins(ctx, acc.GetAddress(), amounts)
err = k.addCoins(ctx, acc.GetAddress(), amounts)
if err != nil {
return err
}
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70 changes: 70 additions & 0 deletions x/bank/keeper/keeper_test.go
Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
package keeper_test

import (
"fmt"
"testing"
"time"

Expand Down Expand Up @@ -1222,6 +1223,75 @@ func (suite *IntegrationTestSuite) getTestMetadata() []types.Metadata {
}
}

func (suite *IntegrationTestSuite) TestMintCoinRestrictions() {
type BankMintingRestrictionFn func(ctx sdk.Context, coins sdk.Coins) error

maccPerms := simapp.GetMaccPerms()
maccPerms[multiPerm] = []string{authtypes.Burner, authtypes.Minter, authtypes.Staking}

suite.app.AccountKeeper = authkeeper.NewAccountKeeper(
suite.app.AppCodec(), suite.app.GetKey(authtypes.StoreKey), suite.app.GetSubspace(authtypes.ModuleName),
authtypes.ProtoBaseAccount, maccPerms)
suite.app.AccountKeeper.SetModuleAccount(suite.ctx, multiPermAcc)

type testCase struct {
coinsToTry sdk.Coin
expectPass bool
}

tests := []struct {
name string
restrictionFn BankMintingRestrictionFn
testCases []testCase
}{
{
"restriction",
func(ctx sdk.Context, coins sdk.Coins) error {
for _, coin := range coins {
if coin.Denom != fooDenom {
return fmt.Errorf("Module %s only has perms for minting %s coins, tried minting %s coins", types.ModuleName, fooDenom, coin.Denom)
}
}
return nil
},
[]testCase{
{
coinsToTry: newFooCoin(100),
expectPass: true,
},
{
coinsToTry: newBarCoin(100),
expectPass: false,
},
},
},
}

for _, test := range tests {
suite.app.BankKeeper = keeper.NewBaseKeeper(suite.app.AppCodec(), suite.app.GetKey(types.StoreKey),
suite.app.AccountKeeper, suite.app.GetSubspace(types.ModuleName), nil).WithMintCoinsRestriction(keeper.BankMintingRestrictionFn(test.restrictionFn))
for _, testCase := range test.testCases {
if testCase.expectPass {
suite.Require().NoError(
suite.app.BankKeeper.MintCoins(
suite.ctx,
multiPermAcc.Name,
sdk.NewCoins(testCase.coinsToTry),
),
)
} else {
suite.Require().Error(
suite.app.BankKeeper.MintCoins(
suite.ctx,
multiPermAcc.Name,
sdk.NewCoins(testCase.coinsToTry),
),
)
}
}
}
}

func TestKeeperTestSuite(t *testing.T) {
suite.Run(t, new(IntegrationTestSuite))
}
3 changes: 3 additions & 0 deletions x/bank/spec/02_keepers.md
Original file line number Diff line number Diff line change
Expand Up @@ -54,11 +54,14 @@ message Output {

The base keeper provides full-permission access: the ability to arbitrary modify any account's balance and mint or burn coins.

Restricted permission to mint per module could be achieved by using baseKeeper with `WithMintCoinsRestriction` to give specific restrictions to mint (e.g. only minting certain denom).

```go
// Keeper defines a module interface that facilitates the transfer of coins
// between accounts.
type Keeper interface {
SendKeeper
WithMintCoinsRestriction(NewRestrictionFn BankMintingRestrictionFn) BaseKeeper

InitGenesis(sdk.Context, *types.GenesisState)
ExportGenesis(sdk.Context) *types.GenesisState
Expand Down

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