Permissions provide fine-grained control over what each role is allowed to do. You can add more permissions to your website. After adding permissions, you must code them manually to a function to restrict a function access. For instance, if you want to restrict currency update rates access to a specific role, you can add a permission like Currencies.Financial.Rates through Permissions module, this permission must be manually added to the update_rates function in the application/currencies/controllers/Financial.php file as follows:
public function update_rates() {$this->auth->restrict('Currency.Financial.Rates');