[keycloak-dev] fine-grain admin permissions with Authz

I'm looking into how we could implement fine-grain admin permissions with Pedro's Authz service, i.e. fix our long standing bug that manage-users allows people to grant themselves admin roles. I want to do an exercise of how certain things can be modeled, specific user role mappings. Some things we want to be able to do * admin can only assign specific roles to users * admin can only assign specific roles to users of a specific group The entire realm would be a Authz resource server. There's already a client (resource server) for the realm "realm-management". - A Scope of "user-role-mapping" would be defined. These resources would be defined and would have the "user-role-mapping" scope attached to them. * "Users" resource. This resource represents all users in the system * A resource is created per role * A resource is created per group Now, when managing roles for a user, we need to ask two questions: 1. Can the admin manage role mappings for this user? 2. Can the admin manage role mappings for this role? For the first question, let's map the current behavior of Keycloak onto the Authz service. * A scoped-base permission would be created for the "Users" resource with a scope of "user-role-mapping" and a role policy of role "manage-users". When role mapping happens, the operation would make an entitlement request for "Users" with a scope of "user-role-mapping". This would pass by default because of the default permission defined above. Now what about the case where we only want an admin to be able to manage roles for a specific group? In this case we define a resource for the Group Foo. The Group Foo would be attached to the "user-role-mapping" scope. Then the realm admin would define a scope-based permission for the Group Foo resource and "user-role-mapping". For example, there might be a "foo-admin" role. The scope permission could grant the permission if the admin has the "foo-admin" role. So, if the "Users"->"user-role-mapping" evaluation fails, the role mapping operation would then cycle through each Group of the user being managed and see if "Group Foo"->"user-role-mapping" evaluates correctly. That's only half of a solution to our problem. We also want to control what roles an admin is allowed to manage. In this case we would have a resource defined for each role in the system. A scoped-based permission would be created for the role's resource and the "user-role-mapping" scope. For example, let's say we wanted to say that only admins with the "admin-role-mapper" role can assign admin roles like "manage-users" or "manage-realm". For the "manage-realm" role resource, we would define a scoped-based permission for "user-role-mapping" with a role policy of "admin-role-mapper". So, let's put this all together. The role mapping operation would do these steps: 1. Can the admin manage role mappings for this user? 1.1 Evaluate that admin can access "user-role-mapping" scope for "Users" resource. If success, goto 2. 1.2 For each group of the user being managed, evaluate that the admin can access "user-role-mapping" scope for that Group. If success goto 2 1.3 Fail the role mapping operation 2. Is the admin allowed to assign the specific role? 2.1 Evaluate that the admin can access the "user-role-mapping" scope for the role's resource.