/
authz.go
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/
authz.go
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// Copyright 2022 Evmos Foundation
// This file is part of the Evmos Network packages.
//
// Evmos is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The Evmos packages are distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the Evmos packages. If not, see https://github.com/evmos/evmos/blob/main/LICENSE
package ante
import (
"fmt"
sdk "github.com/cosmos/cosmos-sdk/types"
sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
"github.com/cosmos/cosmos-sdk/x/authz"
)
// maxNestedMsgs defines a cap for the number of nested messages on a MsgExec message
const maxNestedMsgs = 7
// AuthzLimiterDecorator blocks certain msg types from being granted or executed
// within the authorization module.
type AuthzLimiterDecorator struct {
// disabledMsgTypes is the type urls of the msgs to block.
disabledMsgTypes []string
}
// NewAuthzLimiterDecorator creates a decorator to block certain msg types from being granted or executed within authz.
func NewAuthzLimiterDecorator(disabledMsgTypes ...string) AuthzLimiterDecorator {
return AuthzLimiterDecorator{
disabledMsgTypes: disabledMsgTypes,
}
}
func (ald AuthzLimiterDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) {
if err := ald.checkDisabledMsgs(tx.GetMsgs(), false, 1); err != nil {
return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnauthorized, err.Error())
}
return next(ctx, tx, simulate)
}
// checkDisabledMsgs iterates through the msgs and returns an error if it finds any unauthorized msgs.
//
// When searchOnlyInAuthzMsgs is enabled, only authz MsgGrant and MsgExec are blocked, if they contain unauthorized msg types.
// Otherwise any msg matching the disabled types are blocked, regardless of being in an authz msg or not.
//
// This method is recursive as MsgExec's can wrap other MsgExecs. The check for nested messages is performed up to the
// maxNestedMsgs threshold. If there are more than that limit, it returns an error
func (ald AuthzLimiterDecorator) checkDisabledMsgs(msgs []sdk.Msg, isAuthzInnerMsg bool, nestedLvl int) error {
if nestedLvl >= maxNestedMsgs {
return fmt.Errorf("found more nested msgs than permited. Limit is : %d", maxNestedMsgs)
}
for _, msg := range msgs {
switch msg := msg.(type) {
case *authz.MsgExec:
innerMsgs, err := msg.GetMessages()
if err != nil {
return err
}
nestedLvl++
if err := ald.checkDisabledMsgs(innerMsgs, true, nestedLvl); err != nil {
return err
}
case *authz.MsgGrant:
authorization := msg.GetAuthorization()
if authorization == nil {
return fmt.Errorf("not found authrization")
}
url := authorization.MsgTypeURL()
if ald.isDisabledMsg(url) {
return fmt.Errorf("found disabled msg type: %s", url)
}
default:
url := sdk.MsgTypeURL(msg)
if isAuthzInnerMsg && ald.isDisabledMsg(url) {
return fmt.Errorf("found disabled msg type: %s", url)
}
}
}
return nil
}
// isDisabledMsg returns true if the given message is in the list of restricted
// messages from the AnteHandler.
func (ald AuthzLimiterDecorator) isDisabledMsg(msgTypeURL string) bool {
for _, disabledType := range ald.disabledMsgTypes {
if msgTypeURL == disabledType {
return true
}
}
return false
}