// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (access/AccessControlDefaultAdminRules.sol)
pragma solidity ^0.8.0;
import "./AccessControl.sol";
import "./IAccessControlDefaultAdminRules.sol";
import "../utils/math/SafeCast.sol";
import "../interfaces/IERC5313.sol";
/**
* @dev Extension of {AccessControl} that allows specifying special rules to manage
* the `DEFAULT_ADMIN_ROLE` holder, which is a sensitive role with special permissions
* over other roles that may potentially have privileged rights in the system.
*
* If a specific role doesn't have an admin role assigned, the holder of the
* `DEFAULT_ADMIN_ROLE` will have the ability to grant it and revoke it.
*
* This contract implements the following risk mitigations on top of {AccessControl}:
*
* * Only one account holds the `DEFAULT_ADMIN_ROLE` since deployment until it's potentially renounced.
* * Enforces a 2-step process to transfer the `DEFAULT_ADMIN_ROLE` to another account.
* * Enforces a configurable delay between the two steps, with the ability to cancel before the transfer is accepted.
* * The delay can be changed by scheduling, see {changeDefaultAdminDelay}.
* * It is not possible to use another role to manage the `DEFAULT_ADMIN_ROLE`.
*
* Example usage:
*
* ```solidity
* contract MyToken is AccessControlDefaultAdminRules {
* constructor() AccessControlDefaultAdminRules(
* 3 days,
* msg.sender // Explicit initial `DEFAULT_ADMIN_ROLE` holder
* ) {}
* }
* ```
*
* _Available since v4.9._
*/
abstract contract AccessControlDefaultAdminRules is IAccessControlDefaultAdminRules, IERC5313, AccessControl {
// pending admin pair read/written together frequently
address private _pendingDefaultAdmin;
uint48 private _pendingDefaultAdminSchedule; // 0 == unset
uint48 private _currentDelay;
address private _currentDefaultAdmin;
// pending delay pair read/written together frequently
uint48 private _pendingDelay;
uint48 private _pendingDelaySchedule; // 0 == unset
/**
* @dev Sets the initial values for {defaultAdminDelay} and {defaultAdmin} address.
*/
constructor(uint48 initialDelay, address initialDefaultAdmin) {
require(initialDefaultAdmin != address(0), "AccessControl: 0 default admin");
_currentDelay = initialDelay;
_grantRole(DEFAULT_ADMIN_ROLE, initialDefaultAdmin);
}
/**
* @dev See {IERC165-supportsInterface}.
*/
function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
return interfaceId == type(IAccessControlDefaultAdminRules).interfaceId || super.supportsInterface(interfaceId);
}
/**
* @dev See {IERC5313-owner}.
*/
function owner() public view virtual returns (address) {
return defaultAdmin();
}
///
/// Override AccessControl role management
///
/**
* @dev See {AccessControl-grantRole}. Reverts for `DEFAULT_ADMIN_ROLE`.
*/
function grantRole(bytes32 role, address account) public virtual override(AccessControl, IAccessControl) {
require(role != DEFAULT_ADMIN_ROLE, "AccessControl: can't directly grant default admin role");
super.grantRole(role, account);
}
/**
* @dev See {AccessControl-revokeRole}. Reverts for `DEFAULT_ADMIN_ROLE`.
*/
function revokeRole(bytes32 role, address account) public virtual override(AccessControl, IAccessControl) {
require(role != DEFAULT_ADMIN_ROLE, "AccessControl: can't directly revoke default admin role");
super.revokeRole(role, account);
}
/**
* @dev See {AccessControl-renounceRole}.
*
* For the `DEFAULT_ADMIN_ROLE`, it only allows renouncing in two steps by first calling
* {beginDefaultAdminTransfer} to the `address(0)`, so it's required that the {pendingDefaultAdmin} schedule
* has also passed when calling this function.
*
* After its execution, it will not be possible to call `onlyRole(DEFAULT_ADMIN_ROLE)` functions.
*
* NOTE: Renouncing `DEFAULT_ADMIN_ROLE` will leave the contract without a {defaultAdmin},
* thereby disabling any functionality that is only available for it, and the possibility of reassigning a
* non-administrated role.
*/
function renounceRole(bytes32 role, address account) public virtual override(AccessControl, IAccessControl) {
if (role == DEFAULT_ADMIN_ROLE && account == defaultAdmin()) {
(address newDefaultAdmin, uint48 schedule) = pendingDefaultAdmin();
require(
newDefaultAdmin == address(0) && _isScheduleSet(schedule) && _hasSchedulePassed(schedule),
"AccessControl: only can renounce in two delayed steps"
);
delete _pendingDefaultAdminSchedule;
}
super.renounceRole(role, account);
}
/**
* @dev See {AccessControl-_grantRole}.
*
* For `DEFAULT_ADMIN_ROLE`, it only allows granting if there isn't already a {defaultAdmin} or if the
* role has been previously renounced.
*
* NOTE: Exposing this function through another mechanism may make the `DEFAULT_ADMIN_ROLE`
* assignable again. Make sure to guarantee this is the expected behavior in your implementation.
*/
function _grantRole(bytes32 role, address account) internal virtual override {
if (role == DEFAULT_ADMIN_ROLE) {
require(defaultAdmin() == address(0), "AccessControl: default admin already granted");
_currentDefaultAdmin = account;
}
super._grantRole(role, account);
}
/**
* @dev See {AccessControl-_revokeRole}.
*/
function _revokeRole(bytes32 role, address account) internal virtual override {
if (role == DEFAULT_ADMIN_ROLE && account == defaultAdmin()) {
delete _currentDefaultAdmin;
}
super._revokeRole(role, account);
}
/**
* @dev See {AccessControl-_setRoleAdmin}. Reverts for `DEFAULT_ADMIN_ROLE`.
*/
function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual override {
require(role != DEFAULT_ADMIN_ROLE, "AccessControl: can't violate default admin rules");
super._setRoleAdmin(role, adminRole);
}
///
/// AccessControlDefaultAdminRules accessors
///
/**
* @inheritdoc IAccessControlDefaultAdminRules
*/
function defaultAdmin() public view virtual returns (address) {
return _currentDefaultAdmin;
}
/**
* @inheritdoc IAccessControlDefaultAdminRules
*/
function pendingDefaultAdmin() public view virtual returns (address newAdmin, uint48 schedule) {
return (_pendingDefaultAdmin, _pendingDefaultAdminSchedule);
}
/**
* @inheritdoc IAccessControlDefaultAdminRules
*/
function defaultAdminDelay() public view virtual returns (uint48) {
uint48 schedule = _pendingDelaySchedule;
return (_isScheduleSet(schedule) && _hasSchedulePassed(schedule)) ? _pendingDelay : _currentDelay;
}
/**
* @inheritdoc IAccessControlDefaultAdminRules
*/
function pendingDefaultAdminDelay() public view virtual returns (uint48 newDelay, uint48 schedule) {
schedule = _pendingDelaySchedule;
return (_isScheduleSet(schedule) && !_hasSchedulePassed(schedule)) ? (_pendingDelay, schedule) : (0, 0);
}
/**
* @inheritdoc IAccessControlDefaultAdminRules
*/
function defaultAdminDelayIncreaseWait() public view virtual returns (uint48) {
return 5 days;
}
///
/// AccessControlDefaultAdminRules public and internal setters for defaultAdmin/pendingDefaultAdmin
///
/**
* @inheritdoc IAccessControlDefaultAdminRules
*/
function beginDefaultAdminTransfer(address newAdmin) public virtual onlyRole(DEFAULT_ADMIN_ROLE) {
_beginDefaultAdminTransfer(newAdmin);
}
/**
* @dev See {beginDefaultAdminTransfer}.
*
* Internal function without access restriction.
*/
function _beginDefaultAdminTransfer(address newAdmin) internal virtual {
uint48 newSchedule = SafeCast.toUint48(block.timestamp) + defaultAdminDelay();
_setPendingDefaultAdmin(newAdmin, newSchedule);
emit DefaultAdminTransferScheduled(newAdmin, newSchedule);
}
/**
* @inheritdoc IAccessControlDefaultAdminRules
*/
function cancelDefaultAdminTransfer() public virtual onlyRole(DEFAULT_ADMIN_ROLE) {
_cancelDefaultAdminTransfer();
}
/**
* @dev See {cancelDefaultAdminTransfer}.
*
* Internal function without access restriction.
*/
function _cancelDefaultAdminTransfer() internal virtual {
_setPendingDefaultAdmin(address(0), 0);
}
/**
* @inheritdoc IAccessControlDefaultAdminRules
*/
function acceptDefaultAdminTransfer() public virtual {
(address newDefaultAdmin, ) = pendingDefaultAdmin();
require(_msgSender() == newDefaultAdmin, "AccessControl: pending admin must accept");
_acceptDefaultAdminTransfer();
}
/**
* @dev See {acceptDefaultAdminTransfer}.
*
* Internal function without access restriction.
*/
function _acceptDefaultAdminTransfer() internal virtual {
(address newAdmin, uint48 schedule) = pendingDefaultAdmin();
require(_isScheduleSet(schedule) && _hasSchedulePassed(schedule), "AccessControl: transfer delay not passed");
_revokeRole(DEFAULT_ADMIN_ROLE, defaultAdmin());
_grantRole(DEFAULT_ADMIN_ROLE, newAdmin);
delete _pendingDefaultAdmin;
delete _pendingDefaultAdminSchedule;
}
///
/// AccessControlDefaultAdminRules public and internal setters for defaultAdminDelay/pendingDefaultAdminDelay
///
/**
* @inheritdoc IAccessControlDefaultAdminRules
*/
function changeDefaultAdminDelay(uint48 newDelay) public virtual onlyRole(DEFAULT_ADMIN_ROLE) {
_changeDefaultAdminDelay(newDelay);
}
/**
* @dev See {changeDefaultAdminDelay}.
*
* Internal function without access restriction.
*/
function _changeDefaultAdminDelay(uint48 newDelay) internal virtual {
uint48 newSchedule = SafeCast.toUint48(block.timestamp) + _delayChangeWait(newDelay);
_setPendingDelay(newDelay, newSchedule);
emit DefaultAdminDelayChangeScheduled(newDelay, newSchedule);
}
/**
* @inheritdoc IAccessControlDefaultAdminRules
*/
function rollbackDefaultAdminDelay() public virtual onlyRole(DEFAULT_ADMIN_ROLE) {
_rollbackDefaultAdminDelay();
}
/**
* @dev See {rollbackDefaultAdminDelay}.
*
* Internal function without access restriction.
*/
function _rollbackDefaultAdminDelay() internal virtual {
_setPendingDelay(0, 0);
}
/**
* @dev Returns the amount of seconds to wait after the `newDelay` will
* become the new {defaultAdminDelay}.
*
* The value returned guarantees that if the delay is reduced, it will go into effect
* after a wait that honors the previously set delay.
*
* See {defaultAdminDelayIncreaseWait}.
*/
function _delayChangeWait(uint48 newDelay) internal view virtual returns (uint48) {
uint48 currentDelay = defaultAdminDelay();
// When increasing the delay, we schedule the delay change to occur after a period of "new delay" has passed, up
// to a maximum given by defaultAdminDelayIncreaseWait, by default 5 days. For example, if increasing from 1 day
// to 3 days, the new delay will come into effect after 3 days. If increasing from 1 day to 10 days, the new
// delay will come into effect after 5 days. The 5 day wait period is intended to be able to fix an error like
// using milliseconds instead of seconds.
//
// When decreasing the delay, we wait the difference between "current delay" and "new delay". This guarantees
// that an admin transfer cannot be made faster than "current delay" at the time the delay change is scheduled.
// For example, if decreasing from 10 days to 3 days, the new delay will come into effect after 7 days.
return
newDelay > currentDelay
? uint48(Math.min(newDelay, defaultAdminDelayIncreaseWait())) // no need to safecast, both inputs are uint48
: currentDelay - newDelay;
}
///
/// Private setters
///
/**
* @dev Setter of the tuple for pending admin and its schedule.
*
* May emit a DefaultAdminTransferCanceled event.
*/
function _setPendingDefaultAdmin(address newAdmin, uint48 newSchedule) private {
(, uint48 oldSchedule) = pendingDefaultAdmin();
_pendingDefaultAdmin = newAdmin;
_pendingDefaultAdminSchedule = newSchedule;
// An `oldSchedule` from `pendingDefaultAdmin()` is only set if it hasn't been accepted.
if (_isScheduleSet(oldSchedule)) {
// Emit for implicit cancellations when another default admin was scheduled.
emit DefaultAdminTransferCanceled();
}
}
/**
* @dev Setter of the tuple for pending delay and its schedule.
*
* May emit a DefaultAdminDelayChangeCanceled event.
*/
function _setPendingDelay(uint48 newDelay, uint48 newSchedule) private {
uint48 oldSchedule = _pendingDelaySchedule;
if (_isScheduleSet(oldSchedule)) {
if (_hasSchedulePassed(oldSchedule)) {
// Materialize a virtual delay
_currentDelay = _pendingDelay;
} else {
// Emit for implicit cancellations when another delay was scheduled.
emit DefaultAdminDelayChangeCanceled();
}
}
_pendingDelay = newDelay;
_pendingDelaySchedule = newSchedule;
}
///
/// Private helpers
///
/**
* @dev Defines if an `schedule` is considered set. For consistency purposes.
*/
function _isScheduleSet(uint48 schedule) private pure returns (bool) {
return schedule != 0;
}
/**
* @dev Defines if an `schedule` is considered passed. For consistency purposes.
*/
function _hasSchedulePassed(uint48 schedule) private view returns (bool) {
return schedule < block.timestamp;
}
}