Add an admin endpoint to allow authorizing server to signal token revocations (#16125)

7 files changed, 127 insertions, 0 deletions

diff --git a/synapse/api/auth/msc3861_delegated.py b/synapse/api/auth/msc3861_delegated.py
index 4bdfe31b22..14cba50c90 100644
--- a/synapse/api/auth/msc3861_delegated.py
+++ b/synapse/api/auth/msc3861_delegated.py
@@ -438,3 +438,16 @@ class MSC3861DelegatedAuth(BaseAuth):
             scope=scope,
             is_guest=(has_guest_scope and not has_user_scope),
         )
+
+    def invalidate_cached_tokens(self, keys: List[str]) -> None:
+        """
+        Invalidate the entry(s) in the introspection token cache corresponding to the given key
+        """
+        for key in keys:
+            self._token_cache.invalidate(key)
+
+    def invalidate_token_cache(self) -> None:
+        """
+        Invalidate the entire token cache.
+        """
+        self._token_cache.invalidate_all()
diff --git a/synapse/replication/tcp/client.py b/synapse/replication/tcp/client.py
index 139f57cf86..04e8cff6ea 100644
--- a/synapse/replication/tcp/client.py
+++ b/synapse/replication/tcp/client.py
@@ -26,6 +26,7 @@ from synapse.logging.context import PreserveLoggingContext, make_deferred_yielda
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.replication.tcp.streams import (
     AccountDataStream,
+    CachesStream,
     DeviceListsStream,
     PushersStream,
     PushRulesStream,
@@ -73,6 +74,7 @@ class ReplicationDataHandler:
         self._instance_name = hs.get_instance_name()
         self._typing_handler = hs.get_typing_handler()
         self._state_storage_controller = hs.get_storage_controllers().state
+        self.auth = hs.get_auth()
 
         self._notify_pushers = hs.config.worker.start_pushers
         self._pusher_pool = hs.get_pusherpool()
@@ -218,6 +220,16 @@ class ReplicationDataHandler:
                 self._state_storage_controller.notify_event_un_partial_stated(
                     row.event_id
                 )
+        # invalidate the introspection token cache
+        elif stream_name == CachesStream.NAME:
+            for row in rows:
+                if row.cache_func == "introspection_token_invalidation":
+                    if row.keys[0] is None:
+                        # invalidate the whole cache
+                        # mypy ignore - the token cache is defined on MSC3861DelegatedAuth
+                        self.auth.invalidate_token_cache()  # type: ignore[attr-defined]
+                    else:
+                        self.auth.invalidate_cached_tokens(row.keys)  # type: ignore[attr-defined]
 
         await self._presence_handler.process_replication_rows(
             stream_name, instance_name, token, rows
diff --git a/synapse/rest/admin/__init__.py b/synapse/rest/admin/__init__.py
index fe8177ed4d..55e752fda8 100644
--- a/synapse/rest/admin/__init__.py
+++ b/synapse/rest/admin/__init__.py
@@ -47,6 +47,7 @@ from synapse.rest.admin.federation import (
     ListDestinationsRestServlet,
 )
 from synapse.rest.admin.media import ListMediaInRoom, register_servlets_for_media_repo
+from synapse.rest.admin.oidc import OIDCTokenRevocationRestServlet
 from synapse.rest.admin.registration_tokens import (
     ListRegistrationTokensRestServlet,
     NewRegistrationTokenRestServlet,
@@ -297,6 +298,8 @@ def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     BackgroundUpdateRestServlet(hs).register(http_server)
     BackgroundUpdateStartJobRestServlet(hs).register(http_server)
     ExperimentalFeaturesRestServlet(hs).register(http_server)
+    if hs.config.experimental.msc3861.enabled:
+        OIDCTokenRevocationRestServlet(hs).register(http_server)
 
 
 def register_servlets_for_client_rest_resource(
diff --git a/synapse/rest/admin/oidc.py b/synapse/rest/admin/oidc.py
new file mode 100644
index 0000000000..64d2d40550
--- /dev/null
+++ b/synapse/rest/admin/oidc.py
@@ -0,0 +1,55 @@
+# Copyright 2023 The Matrix.org Foundation C.I.C
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  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 http import HTTPStatus
+from typing import TYPE_CHECKING, Dict, Tuple
+
+from synapse.http.servlet import RestServlet
+from synapse.http.site import SynapseRequest
+from synapse.rest.admin._base import admin_patterns, assert_requester_is_admin
+
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+
+
+class OIDCTokenRevocationRestServlet(RestServlet):
+    """
+    Delete a given token introspection response - identified by the `jti` field - from the
+    introspection token cache when a token is revoked at the authorizing server
+    """
+
+    PATTERNS = admin_patterns("/OIDC_token_revocation/(?P<token_id>[^/]*)")
+
+    def __init__(self, hs: "HomeServer"):
+        super().__init__()
+        auth = hs.get_auth()
+
+        # If this endpoint is loaded then we must have enabled delegated auth.
+        from synapse.api.auth.msc3861_delegated import MSC3861DelegatedAuth
+
+        assert isinstance(auth, MSC3861DelegatedAuth)
+
+        self.auth = auth
+        self.store = hs.get_datastores().main
+
+    async def on_DELETE(
+        self, request: SynapseRequest, token_id: str
+    ) -> Tuple[HTTPStatus, Dict]:
+        await assert_requester_is_admin(self.auth, request)
+
+        self.auth._token_cache.invalidate(token_id)
+
+        # make sure we invalidate the cache on any workers
+        await self.store.stream_introspection_token_invalidation((token_id,))
+
+        return HTTPStatus.OK, {}
diff --git a/synapse/storage/databases/main/cache.py b/synapse/storage/databases/main/cache.py
index 2fbd389c71..18905e07b6 100644
--- a/synapse/storage/databases/main/cache.py
+++ b/synapse/storage/databases/main/cache.py
@@ -584,6 +584,19 @@ class CacheInvalidationWorkerStore(SQLBaseStore):
         else:
             return 0
 
+    async def stream_introspection_token_invalidation(
+        self, key: Tuple[Optional[str]]
+    ) -> None:
+        """
+        Stream an invalidation request for the introspection token cache to workers
+
+        Args:
+            key: token_id of the introspection token to remove from the cache
+        """
+        await self.send_invalidation_to_replication(
+            "introspection_token_invalidation", key
+        )
+
     @wrap_as_background_process("clean_up_old_cache_invalidations")
     async def _clean_up_cache_invalidation_wrapper(self) -> None:
         """
diff --git a/synapse/storage/databases/main/devices.py b/synapse/storage/databases/main/devices.py
index e4162f846b..fa69a4a298 100644
--- a/synapse/storage/databases/main/devices.py
+++ b/synapse/storage/databases/main/devices.py
@@ -33,6 +33,7 @@ from typing_extensions import Literal
 
 from synapse.api.constants import EduTypes
 from synapse.api.errors import Codes, StoreError
+from synapse.config.homeserver import HomeServerConfig
 from synapse.logging.opentracing import (
     get_active_span_text_map,
     set_tag,
@@ -1663,6 +1664,7 @@ class DeviceStore(DeviceWorkerStore, DeviceBackgroundUpdateStore):
         self.device_id_exists_cache: LruCache[
             Tuple[str, str], Literal[True]
         ] = LruCache(cache_name="device_id_exists", max_size=10000)
+        self.config: HomeServerConfig = hs.config
 
     async def store_device(
         self,
@@ -1784,6 +1786,13 @@ class DeviceStore(DeviceWorkerStore, DeviceBackgroundUpdateStore):
         for device_id in device_ids:
             self.device_id_exists_cache.invalidate((user_id, device_id))
 
+        # TODO: don't nuke the entire cache once there is a way to associate
+        #  device_id -> introspection_token
+        if self.config.experimental.msc3861.enabled:
+            # mypy ignore - the token cache is defined on MSC3861DelegatedAuth
+            self.auth._token_cache.invalidate_all()  # type: ignore[attr-defined]
+            await self.stream_introspection_token_invalidation((None,))
+
     async def update_device(
         self, user_id: str, device_id: str, new_display_name: Optional[str] = None
     ) -> None:
diff --git a/synapse/util/caches/expiringcache.py b/synapse/util/caches/expiringcache.py
index 01ad02af67..9a3e10ddee 100644
--- a/synapse/util/caches/expiringcache.py
+++ b/synapse/util/caches/expiringcache.py
@@ -140,6 +140,20 @@ class ExpiringCache(Generic[KT, VT]):
 
         return value.value
 
+    def invalidate(self, key: KT) -> None:
+        """
+        Remove the given key from the cache.
+        """
+
+        value = self._cache.pop(key, None)
+        if value:
+            if self.iterable:
+                self.metrics.inc_evictions(
+                    EvictionReason.invalidation, len(value.value)
+                )
+            else:
+                self.metrics.inc_evictions(EvictionReason.invalidation)
+
     def __contains__(self, key: KT) -> bool:
         return key in self._cache
 
@@ -193,6 +207,14 @@ class ExpiringCache(Generic[KT, VT]):
             len(self),
         )
 
+    def invalidate_all(self) -> None:
+        """
+        Remove all items from the cache.
+        """
+        keys = set(self._cache.keys())
+        for key in keys:
+            self._cache.pop(key)
+
     def __len__(self) -> int:
         if self.iterable:
             return sum(len(entry.value) for entry in self._cache.values())