providers/oauth2: pass scope and other parameters to access policy request context

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

#2641

authentik/policies/views.py

@@ -14,7 +14,7 @@ from authentik.flows.views.executor import SESSION_KEY_APPLICATION_PRE, SESSION_
 from authentik.lib.sentry import SentryIgnoredException
 from authentik.policies.denied import AccessDeniedResponse
 from authentik.policies.engine import PolicyEngine
-from authentik.policies.types import PolicyResult
+from authentik.policies.types import PolicyRequest, PolicyResult
 
 LOGGER = get_logger()
 
@@ -103,11 +103,16 @@ class PolicyAccessView(AccessMixin, View):
             response.policy_result = result
         return response
 
+    def modify_policy_request(self, request: PolicyRequest) -> PolicyRequest:
+        """optionally modify the policy request"""
+        return request
+
     def user_has_access(self, user: Optional[User] = None) -> PolicyResult:
         """Check if user has access to application."""
         user = user or self.request.user
         policy_engine = PolicyEngine(self.application, user or self.request.user, self.request)
         policy_engine.use_cache = False
+        policy_engine.request = self.modify_policy_request(policy_engine.request)
         policy_engine.build()
         result = policy_engine.result
         LOGGER.debug(

authentik/providers/oauth2/views/authorize.py

@@ -27,6 +27,7 @@ from authentik.flows.views.executor import SESSION_KEY_PLAN
 from authentik.lib.utils.time import timedelta_from_string
 from authentik.lib.utils.urls import redirect_with_qs
 from authentik.lib.views import bad_request_message
+from authentik.policies.types import PolicyRequest
 from authentik.policies.views import PolicyAccessView, RequestValidationError
 from authentik.providers.oauth2.constants import (
     PROMPT_CONSNET,
@@ -438,6 +439,16 @@ class AuthorizationFlowInitView(PolicyAccessView):
         self.provider = get_object_or_404(OAuth2Provider, client_id=client_id)
         self.application = self.provider.application
 
+    def modify_policy_request(self, request: PolicyRequest) -> PolicyRequest:
+        request.context["oauth_scopes"] = self.params.scope
+        request.context["oauth_grant_type"] = self.params.grant_type
+        request.context["oauth_code_challenge"] = self.params.code_challenge
+        request.context["oauth_code_challenge_method"] = self.params.code_challenge_method
+        request.context["oauth_max_age"] = self.params.max_age
+        request.context["oauth_redirect_uri"] = self.params.redirect_uri
+        request.context["oauth_response_type"] = self.params.response_type
+        return request
+
     # pylint: disable=unused-argument
     def get(self, request: HttpRequest, *args, **kwargs) -> HttpResponse:
         """Start FlowPLanner, return to flow executor shell"""

authentik/providers/oauth2/views/token.py

@@ -93,6 +93,18 @@ class TokenParams:
             code_verifier=request.POST.get("code_verifier"),
         )
 
+    def __check_policy_access(self, app: Application, request: HttpRequest, **kwargs):
+        engine = PolicyEngine(app, self.user, request)
+        engine.request.context["oauth_scopes"] = self.scope
+        engine.request.context["oauth_grant_type"] = self.grant_type
+        engine.request.context["oauth_code_verifier"] = self.code_verifier
+        engine.request.context.update(kwargs)
+        engine.build()
+        result = engine.result
+        if not result.passing:
+            LOGGER.info("User not authenticated for application", user=self.user, app=app)
+            raise TokenError("invalid_grant")
+
     def __post_init__(self, raw_code: str, raw_token: str, request: HttpRequest):
         if self.grant_type in [GRANT_TYPE_AUTHORIZATION_CODE, GRANT_TYPE_REFRESH_TOKEN]:
             if (
@@ -233,12 +245,7 @@ class TokenParams:
         app = Application.objects.filter(provider=self.provider).first()
         if not app or not app.provider:
             raise TokenError("invalid_grant")
-        engine = PolicyEngine(app, self.user, request)
-        engine.build()
-        result = engine.result
-        if not result.passing:
-            LOGGER.info("User not authenticated for application", user=self.user, app=app)
-            raise TokenError("invalid_grant")
+        self.__check_policy_access(app, request)
         return None
 
     def __post_init_client_credentials_jwt(self, request: HttpRequest):
@@ -279,13 +286,8 @@ class TokenParams:
             LOGGER.info("client_credentials grant for provider without application")
             raise TokenError("invalid_grant")
 
-        engine = PolicyEngine(app, self.user, request)
-        engine.request.context["JWT"] = token
-        engine.build()
-        result = engine.result
-        if not result.passing:
-            LOGGER.info("JWT not authenticated for application", app=app)
-            raise TokenError("invalid_grant")
+        self.__check_policy_access(app, request, oauth_jwt=token)
+
         self.user, _ = User.objects.update_or_create(
             username=f"{self.provider.name}-{token.get('sub')}",
             defaults={

website/docs/providers/oauth2/client_credentials.md

@@ -51,5 +51,5 @@ Input JWTs are checked to be signed by any of the selected *Verification certifi
 To do additional checks, you can use *[Expression policies](../../policies/expression)*:
 
 ```python
-return request.context["JWT"]["iss"] == "https://my.issuer"
+return request.context["oauth_jwt"]["iss"] == "https://my.issuer"
 ```

website/docs/providers/oauth2/index.md

@@ -43,3 +43,14 @@ Refresh tokens can be used as long-lived tokens to access user data, and further
 ### `client_credentials`:
 
 See [Machine-to-machine authentication](./client_credentials)
+
+## Scope authorization
+
+By default, every user that has access to an application can request any of the configured scopes. Starting with authentik 2022.4, you can do additional checks for the scope in an expression policy (bound to the application):
+
+```python
+# There are additional fields set in the context, use `ak_logger.debug(request.context)` to see them.
+if "my-admin-scope" in request.context["oauth_scopes"]:
+    return ak_is_group_member(request.user, name="my-admin-group")
+return True
+```