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Block ERC20 selectors in AMB requests (omni#630)
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k1rill-fedoseev authored Aug 20, 2021
1 parent 39f5835 commit e44f4d8
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Showing 4 changed files with 78 additions and 3 deletions.
Original file line number Diff line number Diff line change
Expand Up @@ -101,6 +101,15 @@ contract BasicAMB is BasicBridge, VersionableAMB {
return boolStorage[ALLOW_REENTRANT_REQUESTS];
}

/**
* @dev Withdraws the erc20 tokens or native coins from this contract.
* @param _token address of the claimed token or address(0) for native coins.
* @param _to address of the tokens/coins receiver.
*/
function claimTokens(address _token, address _to) external onlyIfUpgradeabilityOwner {
claimValues(_token, _to);
}

/**
* Internal function for retrieving current nonce value
* @return nonce value
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Original file line number Diff line number Diff line change
Expand Up @@ -45,7 +45,7 @@ contract BasicHomeAMB is BasicAMB, MessageDelivery {
* @param _data calldata passed to the executor on the other side.
* @param _gas gas limit used on the other network for executing a message.
*/
function requireToConfirmMessage(address _contract, bytes _data, uint256 _gas) external returns (bytes32) {
function requireToConfirmMessage(address _contract, bytes memory _data, uint256 _gas) public returns (bytes32) {
return _sendMessage(_contract, _data, _gas, SEND_TO_MANUAL_LANE);
}

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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,7 @@ contract MessageDelivery is BasicAMB, MessageProcessor {
* @param _data calldata passed to the executor on the other side
* @param _gas gas limit used on the other network for executing a message
*/
function requireToPassMessage(address _contract, bytes _data, uint256 _gas) public returns (bytes32) {
function requireToPassMessage(address _contract, bytes memory _data, uint256 _gas) public returns (bytes32) {
return _sendMessage(_contract, _data, _gas, SEND_TO_ORACLE_DRIVEN_LANE);
}

Expand All @@ -30,12 +30,34 @@ contract MessageDelivery is BasicAMB, MessageProcessor {
* @param _gas gas limit used on the other network for executing a message
* @param _dataType AMB message dataType to be included as a part of the header
*/
function _sendMessage(address _contract, bytes _data, uint256 _gas, uint256 _dataType) internal returns (bytes32) {
function _sendMessage(address _contract, bytes memory _data, uint256 _gas, uint256 _dataType)
internal
returns (bytes32)
{
// it is not allowed to pass messages while other messages are processed
// if other is not explicitly configured
require(messageId() == bytes32(0) || allowReentrantRequests());
require(_gas >= MIN_GAS_PER_CALL && _gas <= maxGasPerTx());

uint256 selector;
assembly {
selector := and(mload(add(_data, 4)), 0xffffffff)
}
// In order to prevent possible unauthorized ERC20 withdrawals, the following function signatures are prohibited:
// * transfer(address,uint256)
// * approve(address,uint256)
// * transferFrom(address,address,uint256)
// * approveAndCall(address,uint256,bytes)
// * transferAndCall(address,uint256,bytes)
// See https://medium.com/immunefi/xdai-stake-arbitrary-call-method-bug-postmortem-f80a90ac56e3 for more details
require(
selector != 0xa9059cbb &&
selector != 0x095ea7b3 &&
selector != 0x23b872dd &&
selector != 0x4000aea0 &&
selector != 0xcae9ca51
);

(bytes32 _messageId, bytes memory header) = _packHeader(_contract, _gas, _dataType);

bytes memory eventData = abi.encodePacked(header, _data);
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44 changes: 44 additions & 0 deletions test/arbitrary_message/foreign_bridge.test.js
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ const HomeBridge = artifacts.require('HomeAMB.sol')
const GasToken = artifacts.require('GasTokenMock.sol')
const BridgeValidators = artifacts.require('BridgeValidators.sol')
const Box = artifacts.require('Box.sol')
const ERC20Mock = artifacts.require('ERC20Mock.sol')
const ERC677ReceiverTest = artifacts.require('ERC677ReceiverTest.sol')
const EternalStorageProxy = artifacts.require('EternalStorageProxy.sol')

Expand Down Expand Up @@ -334,6 +335,49 @@ contract('ForeignAMB', async accounts => {
expect(messageId2).to.include(`${bridgeId}0000000000000001`)
expect(messageId3).to.include(`${bridgeId}0000000000000002`)
})
it('should fail to send message with blocked signatures', async () => {
const blockedFunctions = [
'transfer(address,uint256)',
'approve(address,uint256)',
'transferFrom(address,address,uint256)',
'approveAndCall(address,uint256,bytes)',
'transferAndCall(address,uint256,bytes)'
].map(web3.eth.abi.encodeFunctionSignature)
for (const signature of blockedFunctions) {
await foreignBridge.requireToPassMessage(accounts[7], signature, 10000).should.be.rejected
}
await foreignBridge.requireToPassMessage(accounts[7], '0x11223344', 10000).should.be.fulfilled
})
})
describe('claimTokens', () => {
let foreignBridge
let token
beforeEach(async () => {
const foreignBridgeV1 = await ForeignBridge.new()
token = await ERC20Mock.new('Test', 'TST', 18)

// create proxy
const proxy = await EternalStorageProxy.new()
await proxy.upgradeTo('1', foreignBridgeV1.address).should.be.fulfilled

foreignBridge = await ForeignBridge.at(proxy.address)
await foreignBridge.initialize(
FOREIGN_CHAIN_ID_HEX,
HOME_CHAIN_ID_HEX,
validatorContract.address,
oneEther,
gasPrice,
requiredBlockConfirmations,
owner
)
})
it('should claim mistakenly locked tokens', async () => {
await token.mint(foreignBridge.address, oneEther)
await foreignBridge.claimTokens(token.address, owner, { from: accounts[2] }).should.be.rejected
await foreignBridge.claimTokens(token.address, owner, { from: owner }).should.be.fulfilled

expect(await token.balanceOf(owner)).to.be.bignumber.equal(oneEther)
})
})
describe('executeSignatures', () => {
let foreignBridge
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