Allow tracking puppeted users for MAU (#11561)

Currently when puppeting another user, the user doing the puppeting is
tracked for client IPs and MAU (if configured).

When tracking MAU is important, it becomes necessary to be possible to
also track the client IPs and MAU of puppeted users. As an example a
client that manages user creation and creation of tokens via the Synapse
admin API, passing those tokens for the client to use.

This PR adds optional configuration to enable tracking of puppeted users
into monthly active users. The default behaviour stays the same.

Signed-off-by: Jason Robinson <jasonr@matrix.org>

5 files changed, 63 insertions, 0 deletions

diff --git a/changelog.d/11561.feature b/changelog.d/11561.feature
new file mode 100644
index 0000000000..19dada883b
--- /dev/null
+++ b/changelog.d/11561.feature
@@ -0,0 +1 @@
+Add `track_puppeted_user_ips` config flag to track puppeted user IP addresses. This also includes them in monthly active user counts.
diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
index 810a14b077..26894fae34 100644
--- a/docs/sample_config.yaml
+++ b/docs/sample_config.yaml
@@ -1503,6 +1503,12 @@ room_prejoin_state:
    #additional_event_types:
    #  - org.example.custom.event.type
 
+# If enabled, puppeted user IP's can also be tracked. By default when
+# puppeting another user, the user who has created the access token
+# for puppeting is tracked. If this is enabled, both requests are tracked.
+# Implicitly enables MAU tracking for puppeted users.
+#track_puppeted_user_ips: false
+
 
 # A list of application service config files to use
 #
diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index 4a32d430bd..683241201c 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -71,6 +71,7 @@ class Auth:
         self._auth_blocking = AuthBlocking(self.hs)
 
         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._macaroon_secret_key = hs.config.key.macaroon_secret_key
         self._force_tracing_for_users = hs.config.tracing.force_tracing_for_users
 
@@ -246,6 +247,18 @@ class Auth:
                     user_agent=user_agent,
                     device_id=device_id,
                 )
+                # Track also the puppeted user client IP if enabled and the user is puppeting
+                if (
+                    user_info.user_id != user_info.token_owner
+                    and self._track_puppeted_user_ips
+                ):
+                    await self.store.insert_client_ip(
+                        user_id=user_info.user_id,
+                        access_token=access_token,
+                        ip=ip_addr,
+                        user_agent=user_agent,
+                        device_id=device_id,
+                    )
 
             if is_guest and not allow_guest:
                 raise AuthError(
diff --git a/synapse/config/api.py b/synapse/config/api.py
index 25538b82d5..bdbe9f0fa2 100644
--- a/synapse/config/api.py
+++ b/synapse/config/api.py
@@ -29,6 +29,7 @@ class ApiConfig(Config):
     def read_config(self, config: JsonDict, **kwargs):
         validate_config(_MAIN_SCHEMA, config, ())
         self.room_prejoin_state = list(self._get_prejoin_state_types(config))
+        self.track_puppeted_user_ips = config.get("track_puppeted_user_ips", False)
 
     def generate_config_section(cls, **kwargs) -> str:
         formatted_default_state_types = "\n".join(
@@ -59,6 +60,12 @@ class ApiConfig(Config):
            #
            #additional_event_types:
            #  - org.example.custom.event.type
+
+        # If enabled, puppeted user IP's can also be tracked. By default when
+        # puppeting another user, the user who has created the access token
+        # for puppeting is tracked. If this is enabled, both requests are tracked.
+        # Implicitly enables MAU tracking for puppeted users.
+        #track_puppeted_user_ips: false
         """ % {
             "formatted_default_state_types": formatted_default_state_types
         }
@@ -138,5 +145,8 @@ _MAIN_SCHEMA = {
     "properties": {
         "room_prejoin_state": _ROOM_PREJOIN_STATE_CONFIG_SCHEMA,
         "room_invite_state_types": _ROOM_INVITE_STATE_TYPES_SCHEMA,
+        "track_puppeted_user_ips": {
+            "type": "boolean",
+        },
     },
 }
diff --git a/tests/api/test_auth.py b/tests/api/test_auth.py
index a2dfa1ed05..4b53b6d40b 100644
--- a/tests/api/test_auth.py
+++ b/tests/api/test_auth.py
@@ -274,6 +274,39 @@ class AuthTestCase(unittest.HomeserverTestCase):
         self.assertEquals(failure.value.code, 400)
         self.assertEquals(failure.value.errcode, Codes.EXCLUSIVE)
 
+    def test_get_user_by_req__puppeted_token__not_tracking_puppeted_mau(self):
+        self.store.get_user_by_access_token = simple_async_mock(
+            TokenLookupResult(
+                user_id="@baldrick:matrix.org",
+                device_id="device",
+                token_owner="@admin:matrix.org",
+            )
+        )
+        self.store.insert_client_ip = simple_async_mock(None)
+        request = Mock(args={})
+        request.getClientIP.return_value = "127.0.0.1"
+        request.args[b"access_token"] = [self.test_token]
+        request.requestHeaders.getRawHeaders = mock_getRawHeaders()
+        self.get_success(self.auth.get_user_by_req(request))
+        self.store.insert_client_ip.assert_called_once()
+
+    def test_get_user_by_req__puppeted_token__tracking_puppeted_mau(self):
+        self.auth._track_puppeted_user_ips = True
+        self.store.get_user_by_access_token = simple_async_mock(
+            TokenLookupResult(
+                user_id="@baldrick:matrix.org",
+                device_id="device",
+                token_owner="@admin:matrix.org",
+            )
+        )
+        self.store.insert_client_ip = simple_async_mock(None)
+        request = Mock(args={})
+        request.getClientIP.return_value = "127.0.0.1"
+        request.args[b"access_token"] = [self.test_token]
+        request.requestHeaders.getRawHeaders = mock_getRawHeaders()
+        self.get_success(self.auth.get_user_by_req(request))
+        self.assertEquals(self.store.insert_client_ip.call_count, 2)
+
     def test_get_user_from_macaroon(self):
         self.store.get_user_by_access_token = simple_async_mock(
             TokenLookupResult(user_id="@baldrick:matrix.org", device_id="device")