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Fix BSQ swap buyer tx fee theft vulnerability #5889

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merged 3 commits into from
Dec 4, 2021
Merged

Fix BSQ swap buyer tx fee theft vulnerability #5889

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8d26752
Fix misleading comment: BSQ swap taker tx fee tolerance
stejbac Dec 2, 2021
915a79e
Fix BSQ swap buyer tx fee theft vulnerability
stejbac Dec 2, 2021
0517fac
Validate input script types to prevent BSQ swap tx fee underpaying
stejbac Dec 2, 2021
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26 changes: 22 additions & 4 deletions core/src/main/java/bisq/core/btc/model/RawTransactionInput.java
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,7 @@

package bisq.core.btc.model;

import bisq.core.btc.wallet.BtcWalletService;
import bisq.core.btc.wallet.WalletService;

import bisq.common.proto.network.NetworkPayload;
import bisq.common.proto.persistable.PersistablePayload;
Expand All @@ -36,6 +36,10 @@

import javax.annotation.concurrent.Immutable;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkElementIndex;
import static com.google.common.base.Preconditions.checkNotNull;

@EqualsAndHashCode
@Immutable
@Getter
Expand All @@ -56,7 +60,7 @@ public RawTransactionInput(TransactionInput input) {
input.getConnectedOutput() != null &&
input.getConnectedOutput().getScriptPubKey() != null &&
input.getConnectedOutput().getScriptPubKey().getScriptType() != null ?
input.getConnectedOutput().getScriptPubKey().getScriptType().id : -1);
input.getConnectedOutput().getScriptPubKey().getScriptType().id : 0);
}

// Does not set the scriptTypeId. Use RawTransactionInput(TransactionInput input) for any new code.
Expand Down Expand Up @@ -129,8 +133,22 @@ public boolean isP2WSH() {
return scriptTypeId == Script.ScriptType.P2WSH.id;
}

public String getParentTxId(BtcWalletService btcWalletService) {
return btcWalletService.getTxFromSerializedTx(parentTransaction).getTxId().toString();
public String getParentTxId(WalletService walletService) {
return walletService.getTxFromSerializedTx(parentTransaction).getTxId().toString();
}

public void validate(WalletService walletService) {
Transaction tx = walletService.getTxFromSerializedTx(checkNotNull(parentTransaction));
checkArgument(index == (int) index, "Input index out of range.");
checkElementIndex((int) index, tx.getOutputs().size(), "Input index");
long outputValue = tx.getOutput(index).getValue().value;
checkArgument(value == outputValue,
"Input value (%s) mismatches connected tx output value (%s).", value, outputValue);
var scriptPubKey = tx.getOutput(index).getScriptPubKey();
var scriptType = scriptPubKey != null ? scriptPubKey.getScriptType() : null;
checkArgument(scriptTypeId <= 0 || scriptType != null && scriptType.id == scriptTypeId,
"Input scriptTypeId (%s) mismatches connected tx output scriptTypeId (%s.id = %s).",
scriptTypeId, scriptType, scriptType != null ? scriptType.id : 0);
}

@Override
Expand Down
8 changes: 4 additions & 4 deletions core/src/main/java/bisq/core/trade/bsq_swap/BsqSwapTakeOfferRequestVerification.java
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Expand Up @@ -77,7 +77,7 @@ public static boolean isValid(OpenOfferManager openOfferManager,
checkArgument(isDateInTolerance(request), "Trade date is out of tolerance");
checkArgument(isTxFeeInTolerance(request, feeService), "Miner fee from taker not in tolerance");
checkArgument(request.getMakerFee() == Objects.requireNonNull(CoinUtil.getMakerFee(false, amountAsCoin)).value);
checkArgument(request.getTakerFee() == CoinUtil.getTakerFee(false, amountAsCoin).value);
checkArgument(request.getTakerFee() == Objects.requireNonNull(CoinUtil.getTakerFee(false, amountAsCoin)).value);
} catch (Exception e) {
log.error("BsqSwapTakeOfferRequestVerification failed. Request={}, peer={}, error={}", request, peer, e.toString());
return false;
Expand All @@ -93,9 +93,9 @@ private static boolean isDateInTolerance(BsqSwapRequest request) {
private static boolean isTxFeeInTolerance(BsqSwapRequest request, FeeService feeService) {
double myFee = (double) feeService.getTxFeePerVbyte().getValue();
double peersFee = (double) Coin.valueOf(request.getTxFeePerVbyte()).getValue();
// Allow for 10% diff in mining fee, ie, maker will accept taker fee that's 10%
// off their own fee from service. Both parties will use the same fee while
// creating the bsq swap tx
// Allow for 50% diff in mining fee, ie, maker will accept taker fee that's less
// than 50% off their own fee from service (that is, 100% higher or 50% lower).
// Both parties will use the same fee while creating the bsq swap tx.
double diff = abs(1 - myFee / peersFee);
boolean isInTolerance = diff < 0.5;
if (!isInTolerance) {
Expand Down
19 changes: 14 additions & 5 deletions ...n/java/bisq/core/trade/protocol/bsq_swap/tasks/buyer/ProcessBsqSwapFinalizeTxRequest.java
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Expand Up @@ -19,6 +19,7 @@

import bisq.core.btc.model.RawTransactionInput;
import bisq.core.btc.wallet.Restrictions;
import bisq.core.btc.wallet.WalletService;
import bisq.core.trade.bsq_swap.BsqSwapCalculation;
import bisq.core.trade.model.bsq_swap.BsqSwapTrade;
import bisq.core.trade.protocol.bsq_swap.messages.BsqSwapFinalizeTxRequest;
Expand Down Expand Up @@ -66,19 +67,27 @@ protected void run() {
checkNotNull(request);
Validator.checkTradeId(protocolModel.getOfferId(), request);

// We will use only the sellers buyersBsqInputs from the tx so we do not verify anything else
// We will use only the seller's BTC inputs from the tx, so we do not verify anything else.
byte[] tx = request.getTx();
Transaction sellersTransaction = protocolModel.getBtcWalletService().getTxFromSerializedTx(tx);
WalletService btcWalletService = protocolModel.getBtcWalletService();
Transaction sellersTransaction = btcWalletService.getTxFromSerializedTx(tx);
List<RawTransactionInput> sellersRawBtcInputs = request.getBtcInputs();
checkArgument(!sellersRawBtcInputs.isEmpty(), "Sellers BTC buyersBsqInputs must not be empty");
checkArgument(!sellersRawBtcInputs.isEmpty(), "SellersRawBtcInputs must not be empty");
sellersRawBtcInputs.forEach(input -> input.validate(btcWalletService));

List<RawTransactionInput> buyersBsqInputs = protocolModel.getInputs();
int buyersInputSize = Objects.requireNonNull(buyersBsqInputs).size();
List<TransactionInput> sellersBtcInputs = sellersTransaction.getInputs().stream()
.filter(input -> input.getIndex() >= buyersInputSize)
.collect(Collectors.toList());
checkArgument(sellersBtcInputs.size() == sellersRawBtcInputs.size(),
"Number of buyersBsqInputs in tx must match the number of sellersRawBtcInputs");
"Number of sellersBtcInputs in tx must match the number of sellersRawBtcInputs");
for (int i = 0; i < sellersBtcInputs.size(); i++) {
String parentTxId = sellersBtcInputs.get(i).getOutpoint().getHash().toString();
String rawParentTxId = sellersRawBtcInputs.get(i).getParentTxId(btcWalletService);
checkArgument(parentTxId.equals(rawParentTxId),
"Spending tx mismatch between sellersBtcInputs and sellersRawBtcInputs at index %s", i);
}

boolean hasUnSignedInputs = sellersBtcInputs.stream()
.anyMatch(input -> input.getScriptSig() == null && !input.hasWitness());
Expand Down Expand Up @@ -113,7 +122,7 @@ protected void run() {
checkArgument(change <= expectedChange,
"Change must be smaller or equal to expectedChange");

NetworkParameters params = protocolModel.getBtcWalletService().getParams();
NetworkParameters params = btcWalletService.getParams();
String sellersBsqPayoutAddress = request.getBsqPayoutAddress();
checkNotNull(sellersBsqPayoutAddress, "sellersBsqPayoutAddress must not be null");
checkArgument(!sellersBsqPayoutAddress.isEmpty(), "sellersBsqPayoutAddress must not be empty");
Expand Down
4 changes: 3 additions & 1 deletion .../src/main/java/bisq/core/trade/protocol/bsq_swap/tasks/seller/ProcessTxInputsMessage.java
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Original file line number Diff line number Diff line change
Expand Up @@ -62,16 +62,18 @@ protected void run() {
TxInputsMessage message = checkNotNull((TxInputsMessage) protocolModel.getTradeMessage());
checkNotNull(message);

BtcWalletService btcWalletService = protocolModel.getBtcWalletService();

List<RawTransactionInput> inputs = message.getBsqInputs();
checkArgument(!inputs.isEmpty(), "Buyers BSQ inputs must not be empty");
inputs.forEach(input -> input.validate(btcWalletService));

long sumInputs = inputs.stream().mapToLong(rawTransactionInput -> rawTransactionInput.value).sum();
long buyersBsqInputAmount = BsqSwapCalculation.getBuyersBsqInputValue(trade, getBuyersTradeFee()).getValue();
checkArgument(sumInputs >= buyersBsqInputAmount,
"Buyers BSQ input amount do not match our calculated required BSQ input amount");

DaoFacade daoFacade = protocolModel.getDaoFacade();
BtcWalletService btcWalletService = protocolModel.getBtcWalletService();

long sumValidBsqInputValue = inputs.stream()
.mapToLong(input -> daoFacade.getUnspentTxOutputValue(
Expand Down