From a683028d81606708f686b890c0a44f5a20b54798 Mon Sep 17 00:00:00 2001 From: Brendan Abolivier Date: Wed, 12 May 2021 16:05:28 +0200 Subject: Correctly ratelimit invites when creating a room (#9968) * Correctly ratelimit invites when creating a room Also allow ratelimiting for more than one action at a time. --- changelog.d/9968.bugfix | 1 + synapse/api/ratelimiting.py | 22 +++++++++++---- synapse/handlers/room.py | 27 +++++++++++++----- synapse/handlers/room_member.py | 25 +++++++++++++++++ tests/api/test_ratelimiting.py | 57 ++++++++++++++++++++++++++++++++++++++ tests/rest/client/v1/test_rooms.py | 37 +++++++++++++++++++++++++ 6 files changed, 157 insertions(+), 12 deletions(-) create mode 100644 changelog.d/9968.bugfix diff --git a/changelog.d/9968.bugfix b/changelog.d/9968.bugfix new file mode 100644 index 0000000000..39e75f9956 --- /dev/null +++ b/changelog.d/9968.bugfix @@ -0,0 +1 @@ +Fix a bug introduced in v1.27.0 preventing users and appservices exempt from ratelimiting from creating rooms with many invitees. diff --git a/synapse/api/ratelimiting.py b/synapse/api/ratelimiting.py index 2244b8a340..b9a10283f4 100644 --- a/synapse/api/ratelimiting.py +++ b/synapse/api/ratelimiting.py @@ -57,6 +57,7 @@ class Ratelimiter: rate_hz: Optional[float] = None, burst_count: Optional[int] = None, update: bool = True, + n_actions: int = 1, _time_now_s: Optional[int] = None, ) -> Tuple[bool, float]: """Can the entity (e.g. user or IP address) perform the action? @@ -76,6 +77,9 @@ class Ratelimiter: burst_count: How many actions that can be performed before being limited. Overrides the value set during instantiation if set. update: Whether to count this check as performing the action + n_actions: The number of times the user wants to do this action. If the user + cannot do all of the actions, the user's action count is not incremented + at all. _time_now_s: The current time. Optional, defaults to the current time according to self.clock. Only used by tests. @@ -124,17 +128,20 @@ class Ratelimiter: time_delta = time_now_s - time_start performed_count = action_count - time_delta * rate_hz if performed_count < 0: - # Allow, reset back to count 1 - allowed = True + performed_count = 0 time_start = time_now_s - action_count = 1.0 - elif performed_count > burst_count - 1.0: + + # This check would be easier read as performed_count + n_actions > burst_count, + # but performed_count might be a very precise float (with lots of numbers + # following the point) in which case Python might round it up when adding it to + # n_actions. Writing it this way ensures it doesn't happen. + if performed_count > burst_count - n_actions: # Deny, we have exceeded our burst count allowed = False else: # We haven't reached our limit yet allowed = True - action_count += 1.0 + action_count = performed_count + n_actions if update: self.actions[key] = (action_count, time_start, rate_hz) @@ -182,6 +189,7 @@ class Ratelimiter: rate_hz: Optional[float] = None, burst_count: Optional[int] = None, update: bool = True, + n_actions: int = 1, _time_now_s: Optional[int] = None, ): """Checks if an action can be performed. If not, raises a LimitExceededError @@ -201,6 +209,9 @@ class Ratelimiter: burst_count: How many actions that can be performed before being limited. Overrides the value set during instantiation if set. update: Whether to count this check as performing the action + n_actions: The number of times the user wants to do this action. If the user + cannot do all of the actions, the user's action count is not incremented + at all. _time_now_s: The current time. Optional, defaults to the current time according to self.clock. Only used by tests. @@ -216,6 +227,7 @@ class Ratelimiter: rate_hz=rate_hz, burst_count=burst_count, update=update, + n_actions=n_actions, _time_now_s=time_now_s, ) diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py index fb4823a5cc..835d874cee 100644 --- a/synapse/handlers/room.py +++ b/synapse/handlers/room.py @@ -32,7 +32,14 @@ from synapse.api.constants import ( RoomCreationPreset, RoomEncryptionAlgorithms, ) -from synapse.api.errors import AuthError, Codes, NotFoundError, StoreError, SynapseError +from synapse.api.errors import ( + AuthError, + Codes, + LimitExceededError, + NotFoundError, + StoreError, + SynapseError, +) from synapse.api.filtering import Filter from synapse.api.room_versions import KNOWN_ROOM_VERSIONS, RoomVersion from synapse.events import EventBase @@ -126,10 +133,6 @@ class RoomCreationHandler(BaseHandler): self.third_party_event_rules = hs.get_third_party_event_rules() - self._invite_burst_count = ( - hs.config.ratelimiting.rc_invites_per_room.burst_count - ) - async def upgrade_room( self, requester: Requester, old_room_id: str, new_version: RoomVersion ) -> str: @@ -676,8 +679,18 @@ class RoomCreationHandler(BaseHandler): invite_3pid_list = [] invite_list = [] - if len(invite_list) + len(invite_3pid_list) > self._invite_burst_count: - raise SynapseError(400, "Cannot invite so many users at once") + if invite_list or invite_3pid_list: + try: + # If there are invites in the request, see if the ratelimiting settings + # allow that number of invites to be sent from the current user. + await self.room_member_handler.ratelimit_multiple_invites( + requester, + room_id=None, + n_invites=len(invite_list) + len(invite_3pid_list), + update=False, + ) + except LimitExceededError: + raise SynapseError(400, "Cannot invite so many users at once") await self.event_creation_handler.assert_accepted_privacy_policy(requester) diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py index 20700fc5a8..9a092da715 100644 --- a/synapse/handlers/room_member.py +++ b/synapse/handlers/room_member.py @@ -163,6 +163,31 @@ class RoomMemberHandler(metaclass=abc.ABCMeta): async def forget(self, user: UserID, room_id: str) -> None: raise NotImplementedError() + async def ratelimit_multiple_invites( + self, + requester: Optional[Requester], + room_id: Optional[str], + n_invites: int, + update: bool = True, + ): + """Ratelimit more than one invite sent by the given requester in the given room. + + Args: + requester: The requester sending the invites. + room_id: The room the invites are being sent in. + n_invites: The amount of invites to ratelimit for. + update: Whether to update the ratelimiter's cache. + + Raises: + LimitExceededError: The requester can't send that many invites in the room. + """ + await self._invites_per_room_limiter.ratelimit( + requester, + room_id, + update=update, + n_actions=n_invites, + ) + async def ratelimit_invite( self, requester: Optional[Requester], diff --git a/tests/api/test_ratelimiting.py b/tests/api/test_ratelimiting.py index fa96ba07a5..dcf0110c16 100644 --- a/tests/api/test_ratelimiting.py +++ b/tests/api/test_ratelimiting.py @@ -230,3 +230,60 @@ class TestRatelimiter(unittest.HomeserverTestCase): # Shouldn't raise for _ in range(20): self.get_success_or_raise(limiter.ratelimit(requester, _time_now_s=0)) + + def test_multiple_actions(self): + limiter = Ratelimiter( + store=self.hs.get_datastore(), clock=None, rate_hz=0.1, burst_count=3 + ) + # Test that 4 actions aren't allowed with a maximum burst of 3. + allowed, time_allowed = self.get_success_or_raise( + limiter.can_do_action(None, key="test_id", n_actions=4, _time_now_s=0) + ) + self.assertFalse(allowed) + + # Test that 3 actions are allowed with a maximum burst of 3. + allowed, time_allowed = self.get_success_or_raise( + limiter.can_do_action(None, key="test_id", n_actions=3, _time_now_s=0) + ) + self.assertTrue(allowed) + self.assertEquals(10.0, time_allowed) + + # Test that, after doing these 3 actions, we can't do any more action without + # waiting. + allowed, time_allowed = self.get_success_or_raise( + limiter.can_do_action(None, key="test_id", n_actions=1, _time_now_s=0) + ) + self.assertFalse(allowed) + self.assertEquals(10.0, time_allowed) + + # Test that after waiting we can do only 1 action. + allowed, time_allowed = self.get_success_or_raise( + limiter.can_do_action( + None, + key="test_id", + update=False, + n_actions=1, + _time_now_s=10, + ) + ) + self.assertTrue(allowed) + # The time allowed is the current time because we could still repeat the action + # once. + self.assertEquals(10.0, time_allowed) + + allowed, time_allowed = self.get_success_or_raise( + limiter.can_do_action(None, key="test_id", n_actions=2, _time_now_s=10) + ) + self.assertFalse(allowed) + # The time allowed doesn't change despite allowed being False because, while we + # don't allow 2 actions, we could still do 1. + self.assertEquals(10.0, time_allowed) + + # Test that after waiting a bit more we can do 2 actions. + allowed, time_allowed = self.get_success_or_raise( + limiter.can_do_action(None, key="test_id", n_actions=2, _time_now_s=20) + ) + self.assertTrue(allowed) + # The time allowed is the current time because we could still repeat the action + # once. + self.assertEquals(20.0, time_allowed) diff --git a/tests/rest/client/v1/test_rooms.py b/tests/rest/client/v1/test_rooms.py index a3694f3d02..7c4bdcdfdd 100644 --- a/tests/rest/client/v1/test_rooms.py +++ b/tests/rest/client/v1/test_rooms.py @@ -463,6 +463,43 @@ class RoomsCreateTestCase(RoomBase): ) self.assertEquals(400, channel.code) + @unittest.override_config({"rc_invites": {"per_room": {"burst_count": 3}}}) + def test_post_room_invitees_ratelimit(self): + """Test that invites sent when creating a room are ratelimited by a RateLimiter, + which ratelimits them correctly, including by not limiting when the requester is + exempt from ratelimiting. + """ + + # Build the request's content. We use local MXIDs because invites over federation + # are more difficult to mock. + content = json.dumps( + { + "invite": [ + "@alice1:red", + "@alice2:red", + "@alice3:red", + "@alice4:red", + ] + } + ).encode("utf8") + + # Test that the invites are correctly ratelimited. + channel = self.make_request("POST", "/createRoom", content) + self.assertEqual(400, channel.code) + self.assertEqual( + "Cannot invite so many users at once", + channel.json_body["error"], + ) + + # Add the current user to the ratelimit overrides, allowing them no ratelimiting. + self.get_success( + self.hs.get_datastore().set_ratelimit_for_user(self.user_id, 0, 0) + ) + + # Test that the invites aren't ratelimited anymore. + channel = self.make_request("POST", "/createRoom", content) + self.assertEqual(200, channel.code) + class RoomTopicTestCase(RoomBase): """ Tests /rooms/$room_id/topic REST events. """ -- cgit 1.4.1