fix: Prevent signing from wrong key in multisig

CHANGELOG.md

@@ -82,6 +82,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### Bug Fixes
 
+* [#12548](https://github.com/cosmos/cosmos-sdk/pull/12548) Prevent signing from wrong key while using multisig.
 * [#12416](https://github.com/cosmos/cosmos-sdk/pull/12416) Prevent zero gas transactions in the `DeductFeeDecorator` AnteHandler decorator.
 * (x/mint) [#12384](https://github.com/cosmos/cosmos-sdk/pull/12384) Ensure `GoalBonded` must be positive when performing `x/mint` parameter validation.
 * (x/auth) [#12261](https://github.com/cosmos/cosmos-sdk/pull/12261) Deprecate pagination in GetTxsEventRequest/Response in favor of page and limit to align with tendermint `SignClient.TxSearch`

x/auth/client/cli/tx_sign.go

@@ -9,7 +9,8 @@ import (
 	"github.com/cosmos/cosmos-sdk/client"
 	"github.com/cosmos/cosmos-sdk/client/flags"
 	"github.com/cosmos/cosmos-sdk/client/tx"
-	sdk "github.com/cosmos/cosmos-sdk/types"
+	kmultisig "github.com/cosmos/cosmos-sdk/crypto/keys/multisig"
+
 	authclient "github.com/cosmos/cosmos-sdk/x/auth/client"
 )
 
@@ -224,7 +225,6 @@ func makeSignCmd() func(cmd *cobra.Command, args []string) error {
 			return err
 		}
 
-		txFactory := tx.NewFactoryCLI(clientCtx, cmd.Flags())
 		txCfg := clientCtx.TxConfig
 		txBuilder, err := txCfg.WrapTxBuilder(newTx)
 		if err != nil {
@@ -244,14 +244,39 @@ func makeSignCmd() func(cmd *cobra.Command, args []string) error {
 
 		overwrite, _ := f.GetBool(flagOverwrite)
 		if multisig != "" {
-			multisigAddr, err := sdk.AccAddressFromBech32(multisig)
+			// Bech32 decode error, maybe it's a name, we try to fetch from keyring
+			multisigAddr, multisigName, _, err := client.GetFromFields(clientCtx, txF.Keybase(), multisig)
 			if err != nil {
-				// Bech32 decode error, maybe it's a name, we try to fetch from keyring
-				multisigAddr, _, _, err = client.GetFromFields(clientCtx, txFactory.Keybase(), multisig)
-				if err != nil {
-					return fmt.Errorf("error getting account from keybase: %w", err)
+				return fmt.Errorf("error getting account from keybase: %w", err)
+			}
+			multisigkey, err := getMultisigRecord(clientCtx, multisigName)
+			if err != nil {
+				return err
+			}
+			multisigPubKey, err := multisigkey.GetPubKey()
+			if err != nil {
+				return err
+			}
+			multisigLegacyPub := multisigPubKey.(*kmultisig.LegacyAminoPubKey)
+
+			fromRecord, err := clientCtx.Keyring.Key(fromName)
+			if err != nil {
+				return fmt.Errorf("error getting account from keybase: %w", err)
+			}
+			fromPubKey, err := fromRecord.GetPubKey()
+			if err != nil {
+				return err
+			}
+
+			var found bool
+			for _, pubkey := range multisigLegacyPub.GetPubKeys() {
+				if pubkey.Equals(fromPubKey) {
+					found = true
 				}
 			}
+			if !found {
+				return fmt.Errorf("signing key is not a part of multisig key")
+			}
 			err = authclient.SignTxWithSignerAddress(
 				txF, clientCtx, multisigAddr, fromName, txBuilder, clientCtx.Offline, overwrite)
 			if err != nil {

x/auth/client/testutil/suite.go

@@ -74,6 +74,10 @@ func (s *IntegrationTestSuite) SetupSuite() {
 	pub2, err := account2.GetPubKey()
 	s.Require().NoError(err)
 
+	// Create a dummy account for testing purpose
+	_, _, err = kb.NewMnemonic("dummyAccount", keyring.English, sdk.FullFundraiserPath, keyring.DefaultBIP39Passphrase, hd.Secp256k1)
+	s.Require().NoError(err)
+
 	multi := kmultisig.NewLegacyAminoPubKey(2, []cryptotypes.PubKey{pub1, pub2})
 	_, err = kb.SaveMultisig("multi", multi)
 	s.Require().NoError(err)
@@ -938,6 +942,10 @@ func (s *IntegrationTestSuite) TestCLIMultisignSortSignatures() {
 	multisigRecord, err := val1.ClientCtx.Keyring.Key("multi")
 	s.Require().NoError(err)
 
+	// Generate dummy account which is not a part of multisig.
+	dummyAcc, err := val1.ClientCtx.Keyring.Key("dummyAccount")
+	s.Require().NoError(err)
+
 	addr, err := multisigRecord.GetAddress()
 	s.Require().NoError(err)
 	resp, err := bankcli.QueryBalancesExec(val1.ClientCtx, addr)
@@ -995,14 +1003,21 @@ func (s *IntegrationTestSuite) TestCLIMultisignSortSignatures() {
 
 	sign1File := testutil.WriteToNewTempFile(s.T(), account1Signature.String())
 
-	// Sign with account1
+	// Sign with account2
 	addr2, err := account2.GetAddress()
 	s.Require().NoError(err)
 	account2Signature, err := TxSignExec(val1.ClientCtx, addr2, multiGeneratedTxFile.Name(), "--multisig", addr.String())
 	s.Require().NoError(err)
 
 	sign2File := testutil.WriteToNewTempFile(s.T(), account2Signature.String())
 
+	// Sign with dummy account
+	dummyAddr, err := dummyAcc.GetAddress()
+	s.Require().NoError(err)
+	_, err = TxSignExec(val1.ClientCtx, dummyAddr, multiGeneratedTxFile.Name(), "--multisig", addr.String())
+	s.Require().Error(err)
+	s.Require().Contains(err.Error(), "signing key is not a part of multisig key")
+
 	multiSigWith2Signatures, err := TxMultiSignExec(val1.ClientCtx, multisigRecord.Name, multiGeneratedTxFile.Name(), sign1File.Name(), sign2File.Name())
 	s.Require().NoError(err)
 
@@ -1057,7 +1072,7 @@ func (s *IntegrationTestSuite) TestSignWithMultisig() {
 	// as the main point of this test is to test the `--multisig` flag with an address
 	// that is not in the keyring.
 	_, err = TxSignExec(val1.ClientCtx, addr1, multiGeneratedTx2File.Name(), "--multisig", multisigAddr.String())
-	s.Require().Contains(err.Error(), "tx intended signer does not match the given signer")
+	s.Require().Contains(err.Error(), "error getting account from keybase")
 }
 
 func (s *IntegrationTestSuite) TestCLIMultisign() {
@@ -1124,7 +1139,7 @@ func (s *IntegrationTestSuite) TestCLIMultisign() {
 
 	addr2, err := account2.GetAddress()
 	s.Require().NoError(err)
-	// Sign with account1
+	// Sign with account2
 	account2Signature, err := TxSignExec(val1.ClientCtx, addr2, multiGeneratedTxFile.Name(), "--multisig", addr.String())
 	s.Require().NoError(err)