AFAIK there is no such library. I worked on a project which included RBAC and all we did was (1) define what class of users have access to what program features. (2) When a user logged into the program (needed user name and password) the program looked up the roles database and disabled all program features which the user did not have permisions. Program menus may change at runtime to accommodate the roles.
This is highly application dependent, so I don't know how a general RBAC library could exist.