3 files changed, 53 insertions, 23 deletions

diff --git a/synapse/config/cas.py b/synapse/config/cas.py
index b226890c2a..daea848d24 100644
--- a/synapse/config/cas.py
+++ b/synapse/config/cas.py
@@ -13,7 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from typing import Any, List
+
+from synapse.config.sso import SsoAttributeRequirement
+
 from ._base import Config
+from ._util import validate_config
 
 
 class CasConfig(Config):
@@ -38,12 +43,16 @@ class CasConfig(Config):
                 public_base_url + "_matrix/client/r0/login/cas/ticket"
             )
             self.cas_displayname_attribute = cas_config.get("displayname_attribute")
-            self.cas_required_attributes = cas_config.get("required_attributes") or {}
+            required_attributes = cas_config.get("required_attributes") or {}
+            self.cas_required_attributes = _parsed_required_attributes_def(
+                required_attributes
+            )
+
         else:
             self.cas_server_url = None
             self.cas_service_url = None
             self.cas_displayname_attribute = None
-            self.cas_required_attributes = {}
+            self.cas_required_attributes = []
 
     def generate_config_section(self, config_dir_path, server_name, **kwargs):
         return """\
@@ -75,3 +84,22 @@ class CasConfig(Config):
           #  userGroup: "staff"
           #  department: None
         """
+
+
+# CAS uses a legacy required attributes mapping, not the one provided by
+# SsoAttributeRequirement.
+REQUIRED_ATTRIBUTES_SCHEMA = {
+    "type": "object",
+    "additionalProperties": {"anyOf": [{"type": "string"}, {"type": "null"}]},
+}
+
+
+def _parsed_required_attributes_def(
+    required_attributes: Any,
+) -> List[SsoAttributeRequirement]:
+    validate_config(
+        REQUIRED_ATTRIBUTES_SCHEMA,
+        required_attributes,
+        config_path=("cas_config", "required_attributes"),
+    )
+    return [SsoAttributeRequirement(k, v) for k, v in required_attributes.items()]
diff --git a/synapse/config/saml2_config.py b/synapse/config/saml2_config.py
index ad865a667f..1820614bc0 100644
--- a/synapse/config/saml2_config.py
+++ b/synapse/config/saml2_config.py
@@ -17,8 +17,7 @@
 import logging
 from typing import Any, List
 
-import attr
-
+from synapse.config.sso import SsoAttributeRequirement
 from synapse.python_dependencies import DependencyException, check_requirements
 from synapse.util.module_loader import load_module, load_python_module
 
@@ -396,32 +395,18 @@ class SAML2Config(Config):
         }
 
 
-@attr.s(frozen=True)
-class SamlAttributeRequirement:
-    """Object describing a single requirement for SAML attributes."""
-
-    attribute = attr.ib(type=str)
-    value = attr.ib(type=str)
-
-    JSON_SCHEMA = {
-        "type": "object",
-        "properties": {"attribute": {"type": "string"}, "value": {"type": "string"}},
-        "required": ["attribute", "value"],
-    }
-
-
 ATTRIBUTE_REQUIREMENTS_SCHEMA = {
     "type": "array",
-    "items": SamlAttributeRequirement.JSON_SCHEMA,
+    "items": SsoAttributeRequirement.JSON_SCHEMA,
 }
 
 
 def _parse_attribute_requirements_def(
     attribute_requirements: Any,
-) -> List[SamlAttributeRequirement]:
+) -> List[SsoAttributeRequirement]:
     validate_config(
         ATTRIBUTE_REQUIREMENTS_SCHEMA,
         attribute_requirements,
-        config_path=["saml2_config", "attribute_requirements"],
+        config_path=("saml2_config", "attribute_requirements"),
     )
-    return [SamlAttributeRequirement(**x) for x in attribute_requirements]
+    return [SsoAttributeRequirement(**x) for x in attribute_requirements]
diff --git a/synapse/config/sso.py b/synapse/config/sso.py
index 6c60c6fea4..b94d3cd5e1 100644
--- a/synapse/config/sso.py
+++ b/synapse/config/sso.py
@@ -12,11 +12,28 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from typing import Any, Dict
+from typing import Any, Dict, Optional
+
+import attr
 
 from ._base import Config
 
 
+@attr.s(frozen=True)
+class SsoAttributeRequirement:
+    """Object describing a single requirement for SSO attributes."""
+
+    attribute = attr.ib(type=str)
+    # If a value is not given, than the attribute must simply exist.
+    value = attr.ib(type=Optional[str])
+
+    JSON_SCHEMA = {
+        "type": "object",
+        "properties": {"attribute": {"type": "string"}, "value": {"type": "string"}},
+        "required": ["attribute", "value"],
+    }
+
+
 class SSOConfig(Config):
     """SSO Configuration
     """