[keycloak-dev] Better support for "scope" in adapters
Pedro Igor Silva
psilva at redhat.com
Wed Jan 30 08:40:49 EST 2019
On Wed, Jan 30, 2019 at 5:25 AM Marek Posolda <mposolda at redhat.com> wrote:
> On 29/01/2019 19:49, Pedro Igor Silva wrote:
>
> I'm not sure if we need to consider that in our adapters.
>
> Usually, the front-end knows the set of scopes that it needs to interact
> with the backend and stay functional.
>
> Maybe. I am personally not sure how people expect to use "scope"
> parameters in their frontend applications. Maybe 90% of frontend clients
> don't need to use "scope" parameter at all. And from the remaining, they
> will be fine with the current support of the "scope" parameter.
>
I would say so, mainly because I think people are still using RBAC to
enforce access to APIs. Enterprise scenarios don't really use scopes as
they are more related with delegation.
> One possibility, where I can see usage of this, is when frontend client
> wants to invoke multiple different services and he wants to use different
> access tokens with properly "isolated" audiences. So for example you want
> to have:
>
> - access token with "scope=service1", which will have in itself audience
> claim "aud: service1" and you will use it to invoke backend service1
> - access token with "scope=service2", which will have in itself audience
> claim "aud: service2" and you will use it to invoke backend service2
>
> In this case, having the possibility for adapters to "cache" multiple
> tokens for various scopes can be beneficial IMO, so client can easily
> retrieve proper access token based on the service he wants to invoke.
>
> And the backend by itself is free to exchange tokens to call other
> services (service chaining).
>
> Don't think that brings a lot of complexity to the front-end and,
probably, indicates a bad design?
> IMO in many cases, you're right. For example when frontend client uses
> access token to invoke backend "service1", this backend may want to
> retrieve some other data from "service11". So service1 backend needs to
> reuse the token or he wants to exchange this token.
>
> But in many cases, you want to avoid this. So in my example above, when
> you have access token with "aud: service1", you want this access token to
> be used solely to invoke service1. You don't want to have one huge access
> token, which will have all the audiences like:
>
> aud: [ "service1", "service2" ]
>
The access token is also tied with the client, what means "this client is
allowed to invoke service1 and service2". I usually don't see a problem on
that if you consider that multiple audiences mean that a high degree of
trust between the parties involved. What I think is true for most
enterprise use cases where the front-end is basically accessing internal
services.
It is also worthy to consider, IMO, that the fact that you have distinct
services, does not mean they are not part of the same API, thus the same
audience.
> You may want separate access tokens with isolated audiences exactly
> because you don't want service1 and service2 to be able to invoke each
> other. IMO this isolation is one of the main usages of the "aud" claim in
> the tokens.
>
>
> One thing that makes sense though is "incremental authorization" and allow
> apps to request additional scopes during an authentication session, so the
> app gets what was previously granted and the new scopes (depending on user
> consent). But I think we support that already, right ?
>
> We don't support it directly and maybe this is something to improve. ATM
> you will need programatically do something like this:
>
> String existingScope = existingAccessToken.getScope();
>
> // I want to use existingScope and add "phone" scope to it
> String newScope = existingScope + " phone";
>
> // Request the login for new scope now
>
>
> The part of "requesting login for new scope" is possible with javascript
> adapter, but not easily with the "java" adapter. With java adapter, there
> is no easy way to manually "build" URL to sent to OIDC authentication
> endpoint (equivalent of keycloak.js method "createLoginUrl"). That's also
> one of the things, which I proposed to improve in this email thread.
>
Marek
>
>
> Regards.
> Pedro Igor
>
> On Tue, Jan 29, 2019 at 9:36 AM Marek Posolda <mposolda at redhat.com> wrote:
>
>> During my work on Client Scopes last year, I did not any work on the
>> adapters side. I think there is a space for improvement here. I will try
>> to summary current issues and some initial proposals for improve things.
>> Suggestions welcomed! And sorry for longer email :)
>>
>>
>> Both javascript adapter and servlet adapter has some way for requesting
>> the additional "scope" and ensure that that initial OIDC authentication
>> request sent to Keycloak will contain some custom "scope" parameter. The
>> javascript adapter has support for "scope" as an option of the "login"
>> method [1]. The servlet adapter has a possibility to inject custom
>> "scope" with parameters forwarding [2]. I am not sure about node.js and
>> other adapters TBH. But even for javascript and servlet adapter, the
>> current support is quite limited for few reasons. For example:
>>
>> - The approach of parameters forwarding used in servlet adapters
>> requires to logout before requesting the additional scope. Because when
>> I am already authenticated in the application and I open secured URL
>> like http://localhost/app/secured?scope=some-custom-scope, the adapter
>> will just ignore it in case that user is already logged-in and it will
>> automatically forward to the application.
>>
>> - Both servlet and javascript adapters support to have just single
>> "triplet" of tokens per browser session. In this context "triplet" means
>> the single set of 3 tokens (ID token , Access Token , Refresh token). So
>> for example when I want to request the custom scope for being able to
>> invoke "service1", I can use "scope=service1". However after Keycloak
>> redirects me back to the application, the existing triplet of tokens is
>> just replaced with the new one for "service1" . Then when I want to
>> later invoke another service like "service2", I need to request the
>> additional scope "scope=service2", which will replace my tokens on the
>> adapter's side with the "service2" tokens . But then later when I want
>> to switch again to "service1", I need to redirect to Keycloak again as
>> the current triplet of tokens for "service1" etc.
>>
>>
>> To improve this limitation, I think that it will be good if adapters
>> easily support the following:
>>
>> - Instead of having single triplet of tokens, it will be good if
>> adapters can contain Map of tokens. Key of the map can be "scope"
>> parameter. So for example, the adapter will have "default" tokens
>> (those, which were used for initial login), the tokens for "service1"
>> and the tokens for "service2" .
>>
>> - It will be nice if there is easy way to ask adapter for "service1"
>> scope. In case that I don't have yet this scope, adapter will redirect
>> me to Keycloak with "scope=service1". If I already have it, adapter will
>> return me an existing token. If existing access token is expired,
>> adapter will refresh the access token for requested scope in the
>> background and return me the "updated" token.
>>
>> - When I want to invoke service1 and I need to use "scope=service1", I
>> usually need just access token and refresh token. I don't need ID Token
>> anymore. I also don't need the "profile" and "email" claims to be
>> returned in the new access token. This is related to the JIRA of having
>> the server-side support for client scopes like (always, default,
>> optional) instead of current (default, optional) [3]. In other words,
>> the client scopes "profile" and "email" will be default client scopes,
>> which means that if I don't use "scope=openid" in the OIDC initial
>> request, the "profile" and "email" will be ommited from the response as
>> well as the ID Token will be ommited from the response.
>>
>>
>> So how to support this on adapters? For Keycloak.js, I can think about
>> some variation of existing "update" method like this:
>>
>>
>> keycloak.updateTokenWithScope('service1',
>> 5).success(function(accessToken, refreshed) {
>> if (refreshed) {
>> alert("I had existing accessToken for scope 'service1', but
>> it needed to be refreshed as it was expired or about to expire in less
>> than 5 seconds");
>> } else {
>> alert('I have accessToken for 'service1', which didn't
>> need to be refreshed');
>> }
>> // I can invoke REST service now with the accessToken
>> ...
>> }).error(function() {
>> alert("Failed to refresh the token OR I don't have yet scope
>> for 'service1' .");
>> // User usually need to call keycloak.login with the requested
>> scope now...
>> });
>>
>>
>>
>>
>> For servlet adapter something like:
>>
>> KeycloakSecurityContext ctx = ... // Retrieved from HttpServletRequest
>> or Principal as currently
>>
>> if (ctx.hasScope("service1")) {
>> try {
>> String accessToken = ctx.getScope("service1");
>> // Invoke service1 with accessToken now
>> } catch (TokenRefreshException ex) {
>> log.error("I already had scope for service1, but failed to
>> refresh the token. Need to re-login for the scope service1");
>>
>> // See method below
>> redirectToKeycloakWithService1Scope();
>> }
>> } else {
>> // See method below
>> redirectToKeycloakWithService1Scope();
>> }
>>
>>
>> private void redirectToKeycloakWithService1Scope() {
>> KeycloakRedirectUriBuilder builder = ctx.createLoginUrl();
>> URL url = builder.scope("service1").build();
>> httpServletResponse.sendRedirect(url);
>> }
>>
>>
>> Regarding the class KeycloakRedirectUriBuilder, I was thinking about
>> this class so that servlet adapter are able to easily create login URL
>> with custom values for things like scope, prompt, max_age etc. This
>> capability is currently missing in servlet adapters and the current
>> approach based on parameters forwarding is a bit clunky for few reasons.
>> One reason is usability and the other is, that you need to logout first.
>>
>>
>> [1]
>>
>> https://www.keycloak.org/docs/latest/securing_apps/index.html#javascript-adapter-reference
>> [2]
>>
>> https://www.keycloak.org/docs/latest/securing_apps/index.html#_params_forwarding
>> [3] https://issues.jboss.org/browse/KEYCLOAK-8323
>>
>> Marek
>>
>> _______________________________________________
>> keycloak-dev mailing list
>> keycloak-dev at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/keycloak-dev
>
>
>
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