AccessControlManager

AccessControlManager

Access control plays a crucial role in the Venus governance model. It is used to restrict functions so that they can only be called from one account or list of accounts (EOA or Contract Accounts).

The implementation of AccessControlManager(https://github.com/VenusProtocol/governance-contracts/blob/main/contracts/Governance/AccessControlManager.sol) inherits the Open Zeppelin AccessControl contract as a base for role management logic. There are two role types: admin and granular permissions.

Granular Roles

Granular roles are built by hashing the contract address and its function signature. For example, given contract Foo with function Foo.bar() which is guarded by ACM, calling giveRolePermission for account B do the following:

1. Compute keccak256(contractFooAddress,functionSignatureBar)

2. Add the computed role to the roles of account B

3. Account B now can call ContractFoo.bar()

Admin Roles

Admin roles allow for an address to call a function signature on any contract guarded by the AccessControlManager. This is particularly useful for contracts created by factories.

For Admin roles a null address is hashed in place of the contract address (keccak256(0x0000000000000000000000000000000000000000,functionSignatureBar).

In the previous example, giving account B the admin role, account B will have permissions to call the bar() function on any contract that is guarded by ACM, not only contract A.

Protocol Integration

All restricted functions in Venus Protocol use a hook to ACM in order to check if the caller has the right permission to call the guarded function. AccessControlledV5 and AccessControlledV8 abstract contract makes this integration easier. They call ACM's external method isAllowedToCall(address caller, string functionSig). Here is an example of how setCollateralFactor function in Comptroller is integrated with ACM:

    contract Comptroller is [...] AccessControlledV8 {
        [...]
        function setCollateralFactor(VToken vToken, uint256 newCollateralFactorMantissa, uint256 newLiquidationThresholdMantissa) external {
            _checkAccessAllowed("setCollateralFactor(address,uint256,uint256)");
            [...]
        }
    }

Solidity API

giveCallPermission

Gives a function call permission to one single account

function giveCallPermission(address contractAddress, string functionSig, address accountToPermit) public

Parameters

Name	Type	Description
contractAddress	address	address of contract for which call permissions will be granted
functionSig	string	signature e.g. "functionName(uint256,bool)"
accountToPermit	address	account that will be given access to the contract function

📅 Events

• Emits a {RoleGranted} and {PermissionGranted} events.

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revokeCallPermission

Revokes an account's permission to a particular function call

function revokeCallPermission(address contractAddress, string functionSig, address accountToRevoke) public

Parameters

Name	Type	Description
contractAddress	address	address of contract for which call permissions will be revoked
functionSig	string	signature e.g. "functionName(uint256,bool)"
accountToRevoke	address

📅 Events

• Emits {RoleRevoked} and {PermissionRevoked} events.

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isAllowedToCall

Verifies if the given account can call a contract's guarded function

function isAllowedToCall(address account, string functionSig) public view returns (bool)

Parameters

Name	Type	Description
account	address	for which call permissions will be checked
functionSig	string	restricted function signature e.g. "functionName(uint256,bool)"

Return Values

Name	Type	Description
[0]	bool	false if the user account cannot call the particular contract function

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hasPermission

Verifies if the given account can call a contract's guarded function

function hasPermission(address account, address contractAddress, string functionSig) public view returns (bool)

Parameters

Name	Type	Description
account	address	for which call permissions will be checked against
contractAddress	address	address of the restricted contract
functionSig	string	signature of the restricted function e.g. "functionName(uint256,bool)"

Return Values

Name	Type	Description
[0]	bool	false if the user account cannot call the particular contract function

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