[keycloak-user] Offline Tokens Become Useless When SSO Session Max is Reached

[Scott Finlay]

Hi,

We have an application which creates users in Keycloak using offline tokens. But we're having an issue where Keycloak returns a 401 (unauthorized) when we would try to make requests to it using an access token generated using our offline token. After some investigation we found that there exists a setting in Keycloak called "SSO Session Max" which seems to be an expiration time of the session itself, and after that amount of time, even if the access or refresh tokens are still valid, the session is killed. We found that the amount of time between when we last deployed and the first occurrence of the unauthorized error was 10 hours (the same as the SSO Session Max), and we tested locally with a short max time and were able to reproduce the problem.

Then we found that when we use the offline token, our code thinks that the refresh token expiration time is 0 (which is to be expected since it's an offline token), and when the session lifetime is reached, it continues to use its "unlimited" refresh token to try to generate new access tokens, and it seems that Keycloak still issues new access tokens using that refresh token even though the session doesn't exist, and these tokens don't work. Since Keycloak continues to issue tokens and since it doesn't tell us anything about the session max time, the code has no idea that the tokens are actually not valid.

We can see this happening in the Keycloak admin panel as well; when SSO Sesson Max is reached the session disappears, but the offline session is still there and the "last refresh" time still updates. Inside the token itself we can see that it's still connected to a client session, but we can see no sessions anymore. After looking into the logs of Keycloak we found this error:

16:39:57,664 ERROR [org.jboss.resteasy.resteasy_jaxrs.i18n] (default task-63) RESTEASY002005: Failed executing POST /admin/realms/Myrealm/users: org.jboss.resteasy.spi.UnauthorizedException: Bearer
        at org.keycloak.services.resources.admin.AdminRoot.authenticateRealmAdminRequest(AdminRoot.java:178)
        at org.keycloak.services.resources.admin.AdminRoot.getRealmsAdmin(AdminRoot.java:209)
        at sun.reflect.GeneratedMethodAccessor511.invoke(Unknown Source)

Tracing that through the code of Keycloak we found this which seems to indicate that there must be a valid session associated with tokens:

Starting here: https://github.com/keycloak/keycloak/blob/master/services/src/main/java/org/keycloak/services/resources/admin/AdminRoot.java#L178

Then to here: https://github.com/keycloak/keycloak/blob/master/services/src/main/java/org/keycloak/services/managers/AppAuthManager.java#L58

And finally here: https://github.com/keycloak/keycloak/blob/master/services/src/main/java/org/keycloak/services/managers/AuthenticationManager.java#L731

Is this expected behavior? Are we misunderstanding something or in some way misusing offline tokens?

Regards,
Scott