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Add GovernorTimelockControl address to TimelockController salt #4432

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merged 13 commits into from
Jul 12, 2023
Merged

Add GovernorTimelockControl address to TimelockController salt #4432

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4a9a6aa
Add GovernorTimelockControl address to TimelockController salt
ernestognw Jul 6, 2023
00ff5e1
Add changeset
ernestognw Jul 6, 2023
b63d484
Merge branch 'master' into lib-834-use-governor-address-in-id-hash
ernestognw Jul 9, 2023
bcb0b84
Merge branch 'master' into lib-834-use-governor-address-in-id-hash
ernestognw Jul 12, 2023
fd0ef64
add logging
frangio Jul 12, 2023
5903861
remove only
frangio Jul 12, 2023
ce91062
add only
frangio Jul 12, 2023
29a1b1d
fix only
frangio Jul 12, 2023
4d21d32
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frangio Jul 12, 2023
225c6ec
fix timelockSalt
frangio Jul 12, 2023
3563815
remove console.log
frangio Jul 12, 2023
e775b46
add period
frangio Jul 12, 2023
9dd7f39
Update .changeset/purple-cats-cheer.md
ernestognw Jul 12, 2023
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5 changes: 5 additions & 0 deletions .changeset/purple-cats-cheer.md
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@@ -0,0 +1,5 @@
---
'openzeppelin-solidity': major
---

`GovernorTimelockControl`: Add the Governor instance address as part of the TimelockController operation `salt` to avoid operation id collisions between governors using the same TimelockController.
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17 changes: 14 additions & 3 deletions contracts/governance/extensions/GovernorTimelockControl.sol
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Expand Up @@ -106,8 +106,9 @@ abstract contract GovernorTimelockControl is IGovernorTimelock, Governor {
}

uint256 delay = _timelock.getMinDelay();
_timelockIds[proposalId] = _timelock.hashOperationBatch(targets, values, calldatas, 0, descriptionHash);
_timelock.scheduleBatch(targets, values, calldatas, 0, descriptionHash, delay);
bytes32 salt = _timelockSalt(descriptionHash);
_timelockIds[proposalId] = _timelock.hashOperationBatch(targets, values, calldatas, 0, salt);
_timelock.scheduleBatch(targets, values, calldatas, 0, salt, delay);
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The decision to not have schedule and scheduleBatch return the id that they compute really was a bad one.


emit ProposalQueued(proposalId, block.timestamp + delay);

Expand All @@ -125,7 +126,7 @@ abstract contract GovernorTimelockControl is IGovernorTimelock, Governor {
bytes32 descriptionHash
) internal virtual override {
// execute
_timelock.executeBatch{value: msg.value}(targets, values, calldatas, 0, descriptionHash);
_timelock.executeBatch{value: msg.value}(targets, values, calldatas, 0, _timelockSalt(descriptionHash));
// cleanup for refund
delete _timelockIds[proposalId];
}
Expand Down Expand Up @@ -177,4 +178,14 @@ abstract contract GovernorTimelockControl is IGovernorTimelock, Governor {
emit TimelockChange(address(_timelock), address(newTimelock));
_timelock = newTimelock;
}

/**
* @dev Computes the {TimelockController} operation salt.
*
* It is computed with the governor address itself to avoid collisions across governor instances using the
* same timelock.
*/
function _timelockSalt(bytes32 descriptionHash) private view returns (bytes32) {
return bytes20(address(this)) ^ descriptionHash;
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I decided to use an ^ instead of a keccak256 because it's cheaper and it doesn't matter if the preimage is known since the objective is to avoid unintentional collisions between governors.

If a governor instance wants to purposely block another, it'll require to mine the most significant 20 bytes of the descriptionHash which is infeasible.

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That is an interesting proposal. I'd have done a full hash, just because it would have been clearer to everyone what is going on ... but IMO that is also a valid option.

}
}
8 changes: 6 additions & 2 deletions test/governance/extensions/GovernorTimelockControl.test.js
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Expand Up @@ -37,6 +37,9 @@ contract('GovernorTimelockControl', function (accounts) {

for (const { mode, Token } of TOKENS) {
describe(`using ${Token._json.contractName}`, function () {
const timelockSalt = (address, descriptionHash) =>
'0x' + web3.utils.toBN(address).shln(96).xor(web3.utils.toBN(descriptionHash)).toString(16, 64);

beforeEach(async function () {
const [deployer] = await web3.eth.getAccounts();

Expand Down Expand Up @@ -86,10 +89,11 @@ contract('GovernorTimelockControl', function (accounts) {
],
'<proposal description>',
);

this.proposal.timelockid = await this.timelock.hashOperationBatch(
...this.proposal.shortProposal.slice(0, 3),
'0x0',
this.proposal.shortProposal[3],
timelockSalt(this.mock.address, this.proposal.shortProposal[3]),
);
});

Expand Down Expand Up @@ -204,7 +208,7 @@ contract('GovernorTimelockControl', function (accounts) {
await this.timelock.executeBatch(
...this.proposal.shortProposal.slice(0, 3),
'0x0',
this.proposal.shortProposal[3],
timelockSalt(this.mock.address, this.proposal.shortProposal[3]),
);

await expectRevertCustomError(this.helper.execute(), 'GovernorUnexpectedProposalState', [
Expand Down