How to manage access to the web pages programatically?

Hi. 
I use in my ASP.NET application access control using Forms Authentication with Membership and Role Providers. Currently, the access permissions for individual application pages or entire folders that contain pages I set in my application in the web.config file. This solution is good but the mechanism is static. I mean roles are assigned by the programmer and the user application not having access to the file structure of the application can not change that.   Of course, users can be added to the roles in the application. However, I would go ahead and create a mechanism in which the user application (let's call him an administrator) will be able using application, for each page separately grant permissions by assigning roles to her - that is, each page will have its own combination of assigned roles. These roles will give or deny rights of access. In summary user roles will be compared to the roles of the pages and on the basis of the authorizat ...