Make attribute presence enforcement configurable

Signed-off-by: Ivan Kanakarakis <ivan.kanak@gmail.com>

Author: c00kiemon5ter

src/satosa/micro_services/attribute_authorization.py

@@ -5,62 +5,86 @@
 from ..util import get_dict_defaults
 
 class AttributeAuthorization(ResponseMicroService):
-
     """
-A microservice that performs simple regexp-based authorization based on response
-attributes. The configuration assumes a dict with two keys: attributes_allow
-and attributes_deny. An examples speaks volumes:
+    A microservice that performs simple regexp-based authorization based on response
+    attributes. There are two configuration options to match attribute values in order
+    to allow or deny authorization.
+
+    The configuration is wrapped in two nested dicts that specialize the options per
+    requester (SP/RP) and issuer (IdP/OP).
+
+    There are also two options to enforce presence of the attributes that are going to
+    be checked.
+
+    Example configuration:
 
-```yaml
-config:
-    attribute_allow:
-        target_provider1:
+      ```yaml
+      config:
+        force_attributes_presence_on_allow: true
+        attribute_allow:
+          target_provider1:
             requester1:
-                attr1:
-                   - "^foo:bar$"
-                   - "^kaka$"
+              attr1:
+                - "^foo:bar$"
+                - "^kaka$"
             default:
-                attr1:
-                   - "plupp@.+$"
-        "":
+              attr1:
+                - "plupp@.+$"
+          "":
             "":
-                attr2:
-                   - "^knytte:.*$"
-    attribute_deny:
-        default:
-            default:
-                eppn:
-                   - "^[^@]+$"
+              attr2:
+                - "^knytte:.*$"
 
-```
+        force_attributes_presence_on_deny: false
+        attribute_deny:
+          default:
+            default:
+              eppn:
+                - "^[^@]+$"
+      ```
 
-The use of "" and 'default' is synonymous. Attribute rules are not overloaded
-or inherited. For instance a response from "provider2" would only be allowed
-through if the eppn attribute had all values containing an '@' (something
-perhaps best implemented via an allow rule in practice). Responses from
-target_provider1 bound for requester1 would be allowed through only if attr1
-contained foo:bar or kaka. Note that attribute filters (the leaves of the
-structure above) are ORed together - i.e any attribute match is sufficient.
+    The use of "" and "default" is synonymous. Attribute rules are not overloaded
+    or inherited. For instance a response from "provider2" would only be allowed
+    through if the eppn attribute had all values containing an '@' (something
+    perhaps best implemented via an allow rule in practice). Responses from
+    target_provider1 bound for requester1 would be allowed through only if attr1
+    contained foo:bar or kaka. Note that attribute filters (the leaves of the
+    structure above) are ORed together - i.e any attribute match is sufficient.
     """
 
     def __init__(self, config, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.attribute_allow = config.get("attribute_allow", {})
         self.attribute_deny = config.get("attribute_deny", {})
+        self.force_attributes_presence_on_allow = config.get("force_attributes_presence_on_allow", False)
+        self.force_attributes_presence_on_deny = config.get("force_attributes_presence_on_deny", False)
 
     def _check_authz(self, context, attributes, requester, provider):
         for attribute_name, attribute_filters in get_dict_defaults(self.attribute_allow, requester, provider).items():
-            if attribute_name in attributes:
-                if not any([any(filter(re.compile(af).search, attributes[attribute_name])) for af in attribute_filters]):
+            attr_values = attributes.get(attribute_name)
+            if attr_values is not None:
+                if not any(
+                    [
+                        any(filter(lambda x: re.search(af, x), attr_values))
+                        for af in attribute_filters
+                    ]
+                ):
                     raise SATOSAAuthenticationError(context.state, "Permission denied")
-            else:
+            elif self.force_attributes_presence_on_allow:
                 raise SATOSAAuthenticationError(context.state, "Permission denied")
 
-
         for attribute_name, attribute_filters in get_dict_defaults(self.attribute_deny, requester, provider).items():
-            if attribute_name in attributes:
-                if any([any(filter(re.compile(af).search, attributes[attribute_name])) for af in attribute_filters]):
+            attr_values = attributes.get(attribute_name)
+            if attr_values is not None:
+                if any(
+                    [
+                        any(filter(lambda x: re.search(af, x), attributes[attribute_name]))
+                        for af in attribute_filters
+                    ]
+                ):
                     raise SATOSAAuthenticationError(context.state, "Permission denied")
+            elif self.force_attributes_presence_on_deny:
+                raise SATOSAAuthenticationError(context.state, "Permission denied")
 
     def process(self, context, data):
         self._check_authz(context, data.attributes, data.requester, data.auth_info.issuer)

tests/satosa/micro_services/test_attribute_authorization.py

@@ -6,9 +6,23 @@
 from satosa.context import Context
 
 class TestAttributeAuthorization:
-    def create_authz_service(self, attribute_allow, attribute_deny):
-        authz_service = AttributeAuthorization(config=dict(attribute_allow=attribute_allow,attribute_deny=attribute_deny), name="test_authz",
-                                               base_url="https://satosa.example.com")
+    def create_authz_service(
+        self,
+        attribute_allow,
+        attribute_deny,
+        force_attributes_presence_on_allow=False,
+        force_attributes_presence_on_deny=False,
+    ):
+        authz_service = AttributeAuthorization(
+            config=dict(
+                force_attributes_presence_on_allow=force_attributes_presence_on_allow,
+                force_attributes_presence_on_deny=force_attributes_presence_on_deny,
+                attribute_allow=attribute_allow,
+                attribute_deny=attribute_deny,
+            ),
+            name="test_authz",
+            base_url="https://satosa.example.com",
+        )
         authz_service.next = lambda ctx, data: data
         return authz_service
 
@@ -49,7 +63,7 @@ def test_authz_allow_missing(self):
            "": { "default": {"a0": ['foo1','foo2']} }
         }
         attribute_deny = {}
-        authz_service = self.create_authz_service(attribute_allow, attribute_deny)
+        authz_service = self.create_authz_service(attribute_allow, attribute_deny, force_attributes_presence_on_allow=True)
         resp = InternalData(auth_info=AuthenticationInformation())
         resp.attributes = {
         }