Keep track of `user_ips` and `monthly_active_users` when delegating auth (#16672)

* Describe `insert_client_ip`
* Pull out client_ips and MAU tracking to BaseAuth
* Define HAS_AUTHLIB once in tests

sick of copypasting

* Track ips and token usage when delegating auth
* Test that we track MAU and user_ips
* Don't track `__oidc_admin`

11 files changed, 201 insertions, 82 deletions

diff --git a/changelog.d/16672.feature b/changelog.d/16672.feature
new file mode 100644
index 0000000000..05ecf22207
--- /dev/null
+++ b/changelog.d/16672.feature
@@ -0,0 +1 @@
+Restore tracking of requests and monthly active users when delegating authentication to an [MSC3861](https://github.com/matrix-org/synapse/pull/16672) OIDC provider.
diff --git a/synapse/api/auth/base.py b/synapse/api/auth/base.py
index 9321d6f186..e2e3dc61b4 100644
--- a/synapse/api/auth/base.py
+++ b/synapse/api/auth/base.py
@@ -27,6 +27,8 @@ from synapse.api.errors import (
     UnstableSpecAuthError,
 )
 from synapse.appservice import ApplicationService
+from synapse.http import get_request_user_agent
+from synapse.http.site import SynapseRequest
 from synapse.logging.opentracing import trace
 from synapse.types import Requester, create_requester
 from synapse.util.cancellation import cancellable
@@ -45,6 +47,9 @@ class BaseAuth:
         self.store = hs.get_datastores().main
         self._storage_controllers = hs.get_storage_controllers()
 
+        self._track_appservice_user_ips = hs.config.appservice.track_appservice_user_ips
+        self._track_puppeted_user_ips = hs.config.api.track_puppeted_user_ips
+
     async def check_user_in_room(
         self,
         room_id: str,
@@ -349,3 +354,46 @@ class BaseAuth:
         return create_requester(
             effective_user_id, app_service=app_service, device_id=effective_device_id
         )
+
+    async def _record_request(
+        self, request: SynapseRequest, requester: Requester
+    ) -> None:
+        """Record that this request was made.
+
+        This updates the client_ips and monthly_active_user tables.
+        """
+        ip_addr = request.get_client_ip_if_available()
+
+        if ip_addr and (not requester.app_service or self._track_appservice_user_ips):
+            user_agent = get_request_user_agent(request)
+            access_token = self.get_access_token_from_request(request)
+
+            # XXX(quenting): I'm 95% confident that we could skip setting the
+            # device_id to "dummy-device" for appservices, and that the only impact
+            # would be some rows which whould not deduplicate in the 'user_ips'
+            # table during the transition
+            recorded_device_id = (
+                "dummy-device"
+                if requester.device_id is None and requester.app_service is not None
+                else requester.device_id
+            )
+            await self.store.insert_client_ip(
+                user_id=requester.authenticated_entity,
+                access_token=access_token,
+                ip=ip_addr,
+                user_agent=user_agent,
+                device_id=recorded_device_id,
+            )
+
+            # Track also the puppeted user client IP if enabled and the user is puppeting
+            if (
+                requester.user.to_string() != requester.authenticated_entity
+                and self._track_puppeted_user_ips
+            ):
+                await self.store.insert_client_ip(
+                    user_id=requester.user.to_string(),
+                    access_token=access_token,
+                    ip=ip_addr,
+                    user_agent=user_agent,
+                    device_id=requester.device_id,
+                )
diff --git a/synapse/api/auth/internal.py b/synapse/api/auth/internal.py
index 36ee9c8b8f..985cbb1278 100644
--- a/synapse/api/auth/internal.py
+++ b/synapse/api/auth/internal.py
@@ -22,7 +22,6 @@ from synapse.api.errors import (
     InvalidClientTokenError,
     MissingClientTokenError,
 )
-from synapse.http import get_request_user_agent
 from synapse.http.site import SynapseRequest
 from synapse.logging.opentracing import active_span, force_tracing, start_active_span
 from synapse.types import Requester, create_requester
@@ -48,8 +47,6 @@ class InternalAuth(BaseAuth):
         self._account_validity_handler = hs.get_account_validity_handler()
         self._macaroon_generator = hs.get_macaroon_generator()
 
-        self._track_appservice_user_ips = hs.config.appservice.track_appservice_user_ips
-        self._track_puppeted_user_ips = hs.config.api.track_puppeted_user_ips
         self._force_tracing_for_users = hs.config.tracing.force_tracing_for_users
 
     @cancellable
@@ -115,9 +112,6 @@ class InternalAuth(BaseAuth):
         Once get_user_by_req has set up the opentracing span, this does the actual work.
         """
         try:
-            ip_addr = request.get_client_ip_if_available()
-            user_agent = get_request_user_agent(request)
-
             access_token = self.get_access_token_from_request(request)
 
             # First check if it could be a request from an appservice
@@ -154,38 +148,7 @@ class InternalAuth(BaseAuth):
                             errcode=Codes.EXPIRED_ACCOUNT,
                         )
 
-            if ip_addr and (
-                not requester.app_service or self._track_appservice_user_ips
-            ):
-                # XXX(quenting): I'm 95% confident that we could skip setting the
-                # device_id to "dummy-device" for appservices, and that the only impact
-                # would be some rows which whould not deduplicate in the 'user_ips'
-                # table during the transition
-                recorded_device_id = (
-                    "dummy-device"
-                    if requester.device_id is None and requester.app_service is not None
-                    else requester.device_id
-                )
-                await self.store.insert_client_ip(
-                    user_id=requester.authenticated_entity,
-                    access_token=access_token,
-                    ip=ip_addr,
-                    user_agent=user_agent,
-                    device_id=recorded_device_id,
-                )
-
-                # Track also the puppeted user client IP if enabled and the user is puppeting
-                if (
-                    requester.user.to_string() != requester.authenticated_entity
-                    and self._track_puppeted_user_ips
-                ):
-                    await self.store.insert_client_ip(
-                        user_id=requester.user.to_string(),
-                        access_token=access_token,
-                        ip=ip_addr,
-                        user_agent=user_agent,
-                        device_id=requester.device_id,
-                    )
+            await self._record_request(request, requester)
 
             if requester.is_guest and not allow_guest:
                 raise AuthError(
diff --git a/synapse/api/auth/msc3861_delegated.py b/synapse/api/auth/msc3861_delegated.py
index 31bb035cc8..7373d81534 100644
--- a/synapse/api/auth/msc3861_delegated.py
+++ b/synapse/api/auth/msc3861_delegated.py
@@ -227,6 +227,10 @@ class MSC3861DelegatedAuth(BaseAuth):
             # so that we don't provision the user if they don't have enough permission:
             requester = await self.get_user_by_access_token(access_token, allow_expired)
 
+        # Do not record requests from MAS using the virtual `__oidc_admin` user.
+        if access_token != self._admin_token:
+            await self._record_request(request, requester)
+
         if not allow_guest and requester.is_guest:
             raise OAuthInsufficientScopeError([SCOPE_MATRIX_API])
 
diff --git a/synapse/storage/databases/main/client_ips.py b/synapse/storage/databases/main/client_ips.py
index c006129625..d4b14aaebe 100644
--- a/synapse/storage/databases/main/client_ips.py
+++ b/synapse/storage/databases/main/client_ips.py
@@ -589,6 +589,27 @@ class ClientIpWorkerStore(ClientIpBackgroundUpdateStore, MonthlyActiveUsersWorke
         device_id: Optional[str],
         now: Optional[int] = None,
     ) -> None:
+        """Record that `user_id` used `access_token` from this `ip` address.
+
+        This method does two things.
+
+        1. It queues up a row to be upserted into the `client_ips` table. These happen
+           periodically; see _update_client_ips_batch.
+        2. It immediately records this user as having taken action for the purposes of
+           MAU tracking.
+
+        Any DB writes take place on the background tasks worker, falling back to the
+        main process. If we're not that worker, this method emits a replication payload
+        to run this logic on that worker.
+
+        Two caveats to note:
+
+         - We only take action once per LAST_SEEN_GRANULARITY, to avoid spamming the
+           DB with writes.
+         - Requests using the sliding-sync proxy's user agent are excluded, as its
+           requests are not directly driven by end-users. This is a hack and we're not
+           very proud of it.
+        """
         # The sync proxy continuously triggers /sync even if the user is not
         # present so should be excluded from user_ips entries.
         if user_agent == "sync-v3-proxy-":
diff --git a/tests/config/test_oauth_delegation.py b/tests/config/test_oauth_delegation.py
index 5c91031746..b1a9db0210 100644
--- a/tests/config/test_oauth_delegation.py
+++ b/tests/config/test_oauth_delegation.py
@@ -22,15 +22,7 @@ from synapse.types import JsonDict
 
 from tests.server import get_clock, setup_test_homeserver
 from tests.unittest import TestCase, skip_unless
-from tests.utils import default_config
-
-try:
-    import authlib  # noqa: F401
-
-    HAS_AUTHLIB = True
-except ImportError:
-    HAS_AUTHLIB = False
-
+from tests.utils import HAS_AUTHLIB, default_config
 
 # These are a few constants that are used as config parameters in the tests.
 SERVER_NAME = "test"
diff --git a/tests/handlers/test_oauth_delegation.py b/tests/handlers/test_oauth_delegation.py
index a72ecfdc97..a2b8e3d562 100644
--- a/tests/handlers/test_oauth_delegation.py
+++ b/tests/handlers/test_oauth_delegation.py
@@ -13,7 +13,8 @@
 # limitations under the License.
 
 from http import HTTPStatus
-from typing import Any, Dict, Union
+from io import BytesIO
+from typing import Any, Dict, Optional, Union
 from unittest.mock import ANY, AsyncMock, Mock
 from urllib.parse import parse_qs
 
@@ -25,6 +26,8 @@ from signedjson.key import (
 from signedjson.sign import sign_json
 
 from twisted.test.proto_helpers import MemoryReactor
+from twisted.web.http_headers import Headers
+from twisted.web.iweb import IResponse
 
 from synapse.api.errors import (
     AuthError,
@@ -33,23 +36,17 @@ from synapse.api.errors import (
     OAuthInsufficientScopeError,
     SynapseError,
 )
+from synapse.http.site import SynapseRequest
 from synapse.rest import admin
 from synapse.rest.client import account, devices, keys, login, logout, register
 from synapse.server import HomeServer
-from synapse.types import JsonDict
+from synapse.types import JsonDict, UserID
 from synapse.util import Clock
 
+from tests.server import FakeChannel
 from tests.test_utils import FakeResponse, get_awaitable_result
-from tests.unittest import HomeserverTestCase, skip_unless
-from tests.utils import mock_getRawHeaders
-
-try:
-    import authlib  # noqa: F401
-
-    HAS_AUTHLIB = True
-except ImportError:
-    HAS_AUTHLIB = False
-
+from tests.unittest import HomeserverTestCase, override_config, skip_unless
+from tests.utils import HAS_AUTHLIB, checked_cast, mock_getRawHeaders
 
 # These are a few constants that are used as config parameters in the tests.
 SERVER_NAME = "test"
@@ -75,6 +72,7 @@ MATRIX_DEVICE_SCOPE = MATRIX_DEVICE_SCOPE_PREFIX + DEVICE
 SUBJECT = "abc-def-ghi"
 USERNAME = "test-user"
 USER_ID = "@" + USERNAME + ":" + SERVER_NAME
+OIDC_ADMIN_USERID = f"@__oidc_admin:{SERVER_NAME}"
 
 
 async def get_json(url: str) -> JsonDict:
@@ -134,7 +132,10 @@ class MSC3861OAuthDelegation(HomeserverTestCase):
 
         hs = self.setup_test_homeserver(proxied_http_client=self.http_client)
 
-        self.auth = hs.get_auth()
+        # Import this here so that we've checked that authlib is available.
+        from synapse.api.auth.msc3861_delegated import MSC3861DelegatedAuth
+
+        self.auth = checked_cast(MSC3861DelegatedAuth, hs.get_auth())
 
         return hs
 
@@ -675,7 +676,8 @@ class MSC3861OAuthDelegation(HomeserverTestCase):
         request.requestHeaders.getRawHeaders = mock_getRawHeaders()
         requester = self.get_success(self.auth.get_user_by_req(request))
         self.assertEqual(
-            requester.user.to_string(), "@%s:%s" % ("__oidc_admin", SERVER_NAME)
+            requester.user.to_string(),
+            OIDC_ADMIN_USERID,
         )
         self.assertEqual(requester.is_guest, False)
         self.assertEqual(requester.device_id, None)
@@ -685,3 +687,102 @@ class MSC3861OAuthDelegation(HomeserverTestCase):
 
         # There should be no call to the introspection endpoint
         self.http_client.request.assert_not_called()
+
+    @override_config({"mau_stats_only": True})
+    def test_request_tracking(self) -> None:
+        """Using an access token should update the client_ips and MAU tables."""
+        # To start, there are no MAU users.
+        store = self.hs.get_datastores().main
+        mau = self.get_success(store.get_monthly_active_count())
+        self.assertEqual(mau, 0)
+
+        known_token = "token-token-GOOD-:)"
+
+        async def mock_http_client_request(
+            method: str,
+            uri: str,
+            data: Optional[bytes] = None,
+            headers: Optional[Headers] = None,
+        ) -> IResponse:
+            """Mocked auth provider response."""
+            assert method == "POST"
+            token = parse_qs(data)[b"token"][0].decode("utf-8")
+            if token == known_token:
+                return FakeResponse.json(
+                    code=200,
+                    payload={
+                        "active": True,
+                        "scope": MATRIX_USER_SCOPE,
+                        "sub": SUBJECT,
+                        "username": USERNAME,
+                    },
+                )
+
+            return FakeResponse.json(code=200, payload={"active": False})
+
+        self.http_client.request = mock_http_client_request
+
+        EXAMPLE_IPV4_ADDR = "123.123.123.123"
+        EXAMPLE_USER_AGENT = "httprettygood"
+
+        # First test a known access token
+        channel = FakeChannel(self.site, self.reactor)
+        # type-ignore: FakeChannel is a mock of an HTTPChannel, not a proper HTTPChannel
+        req = SynapseRequest(channel, self.site)  # type: ignore[arg-type]
+        req.client.host = EXAMPLE_IPV4_ADDR
+        req.requestHeaders.addRawHeader("Authorization", f"Bearer {known_token}")
+        req.requestHeaders.addRawHeader("User-Agent", EXAMPLE_USER_AGENT)
+        req.content = BytesIO(b"")
+        req.requestReceived(
+            b"GET",
+            b"/_matrix/client/v3/account/whoami",
+            b"1.1",
+        )
+        channel.await_result()
+        self.assertEqual(channel.code, HTTPStatus.OK, channel.json_body)
+        self.assertEqual(channel.json_body["user_id"], USER_ID, channel.json_body)
+
+        # Expect to see one MAU entry, from the first request
+        mau = self.get_success(store.get_monthly_active_count())
+        self.assertEqual(mau, 1)
+
+        conn_infos = self.get_success(
+            store.get_user_ip_and_agents(UserID.from_string(USER_ID))
+        )
+        self.assertEqual(len(conn_infos), 1, conn_infos)
+        conn_info = conn_infos[0]
+        self.assertEqual(conn_info["access_token"], known_token)
+        self.assertEqual(conn_info["ip"], EXAMPLE_IPV4_ADDR)
+        self.assertEqual(conn_info["user_agent"], EXAMPLE_USER_AGENT)
+
+        # Now test MAS making a request using the special __oidc_admin token
+        MAS_IPV4_ADDR = "127.0.0.1"
+        MAS_USER_AGENT = "masmasmas"
+
+        channel = FakeChannel(self.site, self.reactor)
+        req = SynapseRequest(channel, self.site)  # type: ignore[arg-type]
+        req.client.host = MAS_IPV4_ADDR
+        req.requestHeaders.addRawHeader(
+            "Authorization", f"Bearer {self.auth._admin_token}"
+        )
+        req.requestHeaders.addRawHeader("User-Agent", MAS_USER_AGENT)
+        req.content = BytesIO(b"")
+        req.requestReceived(
+            b"GET",
+            b"/_matrix/client/v3/account/whoami",
+            b"1.1",
+        )
+        channel.await_result()
+        self.assertEqual(channel.code, HTTPStatus.OK, channel.json_body)
+        self.assertEqual(
+            channel.json_body["user_id"], OIDC_ADMIN_USERID, channel.json_body
+        )
+
+        # Still expect to see one MAU entry, from the first request
+        mau = self.get_success(store.get_monthly_active_count())
+        self.assertEqual(mau, 1)
+
+        conn_infos = self.get_success(
+            store.get_user_ip_and_agents(UserID.from_string(OIDC_ADMIN_USERID))
+        )
+        self.assertEqual(conn_infos, [])
diff --git a/tests/rest/admin/test_jwks.py b/tests/rest/admin/test_jwks.py
index a9a6191c73..842e92c3d0 100644
--- a/tests/rest/admin/test_jwks.py
+++ b/tests/rest/admin/test_jwks.py
@@ -19,13 +19,7 @@ from twisted.web.resource import Resource
 from synapse.rest.synapse.client import build_synapse_client_resource_tree
 
 from tests.unittest import HomeserverTestCase, override_config, skip_unless
-
-try:
-    import authlib  # noqa: F401
-
-    HAS_AUTHLIB = True
-except ImportError:
-    HAS_AUTHLIB = False
+from tests.utils import HAS_AUTHLIB
 
 
 @skip_unless(HAS_AUTHLIB, "requires authlib")
diff --git a/tests/rest/client/test_keys.py b/tests/rest/client/test_keys.py
index 9f81a695fa..a6023dff7a 100644
--- a/tests/rest/client/test_keys.py
+++ b/tests/rest/client/test_keys.py
@@ -30,13 +30,7 @@ from synapse.types import JsonDict, Requester, create_requester
 from tests import unittest
 from tests.http.server._base import make_request_with_cancellation_test
 from tests.unittest import override_config
-
-try:
-    import authlib  # noqa: F401
-
-    HAS_AUTHLIB = True
-except ImportError:
-    HAS_AUTHLIB = False
+from tests.utils import HAS_AUTHLIB
 
 
 class KeyQueryTestCase(unittest.HomeserverTestCase):
diff --git a/tests/rest/test_well_known.py b/tests/rest/test_well_known.py
index 377243a170..7931a70abb 100644
--- a/tests/rest/test_well_known.py
+++ b/tests/rest/test_well_known.py
@@ -16,13 +16,7 @@ from twisted.web.resource import Resource
 from synapse.rest.well_known import well_known_resource
 
 from tests import unittest
-
-try:
-    import authlib  # noqa: F401
-
-    HAS_AUTHLIB = True
-except ImportError:
-    HAS_AUTHLIB = False
+from tests.utils import HAS_AUTHLIB
 
 
 class WellKnownTests(unittest.HomeserverTestCase):
diff --git a/tests/utils.py b/tests/utils.py
index a0c87ad628..e0066fe15a 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -30,6 +30,13 @@ from synapse.storage.database import LoggingDatabaseConnection
 from synapse.storage.engines import create_engine
 from synapse.storage.prepare_database import prepare_database
 
+try:
+    import authlib  # noqa: F401
+
+    HAS_AUTHLIB = True
+except ImportError:
+    HAS_AUTHLIB = False
+
 # set this to True to run the tests against postgres instead of sqlite.
 #
 # When running under postgres, we first create a base database with the name