Add rate limit conf to client profile endpoint

Author: MatMaul

changelog.d/19292.misc

@@ -0,0 +1 @@
+Add a config to be able to rate limit profile lookups by clients.

docs/usage/configuration/config_documentation.md

@@ -2041,6 +2041,25 @@ rc_room_creation:
   burst_count: 5.0
 ```
 ---
+### `rc_profile`
+
+*(object)* This option allows admins to ratelimit profile lookups by clients.
+
+_Added in Synapse 1.145.0._
+
+This setting has the following sub-options:
+
+* `per_second` (number): Maximum number of requests a client can send per second.
+
+* `burst_count` (number): Maximum number of requests a client can send before being throttled.
+
+Default configuration:
+```yaml
+rc_profile:
+  per_second: 0.016
+  burst_count: 10.0
+```
+---
 ### `federation_rr_transactions_per_room_per_second`
 
 *(integer)* Sets outgoing federation transaction frequency for sending read-receipts, per-room.

schema/synapse-config.schema.yaml

@@ -2274,6 +2274,16 @@ properties:
     examples:
       - per_second: 1.0
         burst_count: 5.0
+  rc_profile:
+    $ref: "#/$defs/rc"
+    description: >-
+      This option allows admins to ratelimit profile lookups by clients.
+
+
+      _Added in Synapse 1.145.0._
+    default:
+      per_second: 1
+      burst_count: 500.0
   federation_rr_transactions_per_room_per_second:
     type: integer
     description: >-

synapse/config/ratelimiting.py

@@ -252,3 +252,9 @@ def read_config(self, config: JsonDict, **kwargs: Any) -> None:
             "rc_reports",
             defaults={"per_second": 1, "burst_count": 5},
         )
+
+        self.rc_profile = RatelimitSettings.parse(
+            config,
+            "rc_profile",
+            defaults={"per_second": 1, "burst_count": 500},
+        )

synapse/rest/client/profile.py

@@ -27,6 +27,7 @@
 
 from synapse.api.constants import ProfileFields
 from synapse.api.errors import Codes, SynapseError
+from synapse.api.ratelimiting import Ratelimiter
 from synapse.handlers.profile import MAX_CUSTOM_FIELD_LEN
 from synapse.http.server import HttpServer
 from synapse.http.servlet import (
@@ -67,22 +68,26 @@ def __init__(self, hs: "HomeServer"):
         self.profile_handler = hs.get_profile_handler()
         self.auth = hs.get_auth()
 
+        self._per_user_limiter = Ratelimiter(
+            store=hs.get_datastores().main,
+            clock=hs.get_clock(),
+            cfg=hs.config.ratelimiting.rc_profile,
+        )
+
     async def on_GET(
         self, request: SynapseRequest, user_id: str
     ) -> tuple[int, JsonDict]:
-        requester_user = None
-
-        if self.hs.config.server.require_auth_for_profile_requests:
-            requester = await self.auth.get_user_by_req(request)
-            requester_user = requester.user
-
         if not UserID.is_valid(user_id):
             raise SynapseError(
                 HTTPStatus.BAD_REQUEST, "Invalid user id", Codes.INVALID_PARAM
             )
 
         user = UserID.from_string(user_id)
-        await self.profile_handler.check_profile_query_allowed(user, requester_user)
+
+        requester = await self.auth.get_user_by_req(request)
+        await self._per_user_limiter.ratelimit(requester)
+        if self.hs.config.server.require_auth_for_profile_requests:
+            await self.profile_handler.check_profile_query_allowed(user, requester.user)
 
         ret = await self.profile_handler.get_profile(user_id)
 
@@ -116,15 +121,15 @@ def __init__(self, hs: "HomeServer"):
                 )
             )
 
+        self._per_user_limiter = Ratelimiter(
+            store=hs.get_datastores().main,
+            clock=hs.get_clock(),
+            cfg=hs.config.ratelimiting.rc_profile,
+        )
+
     async def on_GET(
         self, request: SynapseRequest, user_id: str, field_name: str
     ) -> tuple[int, JsonDict]:
-        requester_user = None
-
-        if self.hs.config.server.require_auth_for_profile_requests:
-            requester = await self.auth.get_user_by_req(request)
-            requester_user = requester.user
-
         if not UserID.is_valid(user_id):
             raise SynapseError(
                 HTTPStatus.BAD_REQUEST, "Invalid user id", Codes.INVALID_PARAM
@@ -143,7 +148,11 @@ async def on_GET(
             )
 
         user = UserID.from_string(user_id)
-        await self.profile_handler.check_profile_query_allowed(user, requester_user)
+
+        requester = await self.auth.get_user_by_req(request)
+        await self._per_user_limiter.ratelimit(requester)
+        if self.hs.config.server.require_auth_for_profile_requests:
+            await self.profile_handler.check_profile_query_allowed(user, requester.user)
 
         if field_name == ProfileFields.DISPLAYNAME:
             field_value: JsonValue = await self.profile_handler.get_displayname(user)