[keycloak-user] FW: Access control and client setup

[Wyns Dean]

Hi Pedro

Thanks, that has clarified a lot already.

There are still some things that we’re a bit uncertain about.


  1.  Can you restrict scopes to certain roles? Like for example the OAuth client requests scope “item:read item:delete”, but the authenticated user only has the role to view items. So I would expect the resulting scope in the access token to be “item:view”, but Keycloak always seems to put the requested scope in the access token (+ the default client scopes). I understand that Keycloak uses scope to limit the role mappings that get assigned to the access token. I’m just wondering if we could use the scope as “permissions granted” if we could restrict it (just like Auth0, where they limit the scope according to the user’s permissions and the server checks the scope).
  2.  Is it possible to remove/hide the “resource_access” and/or “realm_access” claims from the access token?
  3.  Is it possible to add a custom claim “permissions” to the token which is the list of the user’s roles (with a script protocol mapper maybe?)
  4.  What is the recommended way to model simple authorization? Still not really sure which way to go.
The API is just a simple CRUD for some models (items, item types, …), and each model has a permission/role for each action (create, read, update, delete). Would you go with authorization based on OAuth scopes (client scopes) or with the authorization model that Keycloak provides? We don’t really need the fine-grained permissions yet, so I’d say we’d go with the client scopes.


Thanks a lot!

Kind regards
Dean

Van: Pedro Igor Silva <psilva at redhat.com>
Verzonden: Monday 30 July 2018 17:52
Aan: Wyns Dean <dean.wyns at aptus.be>
CC: keycloak-user at lists.jboss.org
Onderwerp: Re: [keycloak-user] FW: Access control and client setup

On Mon, Jul 30, 2018 at 10:43 AM, Wyns Dean <dean.wyns at aptus.be<mailto:dean.wyns at aptus.be>> wrote:
Hi Pedro

Thanks for your answer.

So the idea is to create one client for the API, let’s call it “my-api” with authorization enabled and the resources/scopes/permissions like you described previously. And I’ll create another (public) client for the SPA, “my-app”.

If users authenticate against my-app using the implicit flow, how can I link the scopes associated with the resources of my-api and have them follow the permissions that are defined on my-api? Do I have to add the scopes as optional “Client Scopes” so they are shared? The problem then is that they don’t show up under the Authorization tab of my-api, only the Authorization Scopes do. Or should authorization be enabled for my-app as well?

Client Scopes and Authorization tabs are different features. The first provides an authorization model based on OAuth2 scopes, where scopes may map to one or more claims inside your token or even restrict the roles you send n the token. They are also related with user consent.

The Authorization provides you the necessary means to setup resource-based permissions using different access control mechanisms. It also provides privacy based on user-managed access.


I would like the backend to purely check on the scope associated with the access token, by looking at the scope claim. There doesn’t seem to ever be a permissions claim in my tests, I only get the “resource_access” claim but that only contains the roles, which I don’t need in the backend.

Are these scopes a result of user consent ? Or do you need more fine-grained control and externalize authorization from my-api ?

Are you using a specific Keycloak adapter ? (wildfly, spring, etc)


Sorry if I’m being unclear.

Your help is highly appreciated!
Dean

Van: Pedro Igor Silva <psilva at redhat.com<mailto:psilva at redhat.com>>
Verzonden: donderdag 26 juli 2018 14:00
Aan: Wyns Dean <dean.wyns at aptus.be<mailto:dean.wyns at aptus.be>>
CC: keycloak-user at lists.jboss.org<mailto:keycloak-user at lists.jboss.org>
Onderwerp: Re: [keycloak-user] FW: Access control and client setup



On Wed, Jul 25, 2018 at 4:21 AM, Wyns Dean <dean.wyns at aptus.be<mailto:dean.wyns at aptus.be>> wrote:
Hi

I'm evaluating Keycloak as our IAM and SSO and it seems very powerful, but I can't seem to wrap my head around some things.

We want to separate our APIs from the IAM. The sole purpose of Keycloak is to provide an identity and access token, primarily using the implicit flow. The client-side application (usually SPAs) uses the access token in all API calls and the resource server checks the signature of the access token but does not access Keycloak at all.

Each backend has a few operations, and each operation gets its own "permission". For example one API can manage "items", so there are four permissions:
- create:item
- read:item
- update:item
- delete:item

Is it best practice with Keycloak to model these permissions as scopes? And then use roles/permissions/policies to limit the scope of the user? The backend can then just decode the access token and read the granted scopes.

Ideally, you should define your authorization settings based on on your model. So if you have a resource "Item", which is a protected resource in your API you should have a "Item Resource" in Keycloak. The actions/methods create, read, update and delete can be scopes associated with your "Item" resource.

Once you have your item resource and scopes, you can define permissions that govern access for the resource itself or for each scope individually. All depends on how you create those permissions (resource vs scope permissions) and policies associated with them.

The backend could just decode the token and check for the "permissions" claim. Or you can also query the Keycloak server on every request to obtain a decision.


Also, in a SPA + API set-up, do I create two clients in Keycloak, one for each? This is only useful when the API needs resource protection, right? I guess in my case I only need one client for the SPA because the API only needs the scope from the access token by decoding it.

I would say you should have two clients representing both applications. They have different requirements and are really different things. Your SPA is probably a reguar public client while your API is a resource server.


Thanks for any feedback

Kind regards
Dean


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