Add logic for Mjolnir antispam module

synapse_antispam/mjolnir/antispam.py

@@ -1,14 +1,100 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 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.
+
+import logging
+from .list_rule import ALL_RULE_TYPES, RECOMMENDATION_BAN
+from .ban_list import BanList
+from synapse.types import UserID
+
+logger = logging.getLogger("synapse.contrib." + __name__)
+
 class AntiSpam(object):
-    def __init__(self, config):
-        self._block_invites = config.get("block_invites", True)
-        self._block_messages = config.get("block_messages", False)
-        self._list_room_ids = config.get("ban_lists", [])
+    def __init__(self, config, hs):
+        self.block_invites = config.get("block_invites", True)
+        self.block_messages = config.get("block_messages", False)
+        self.list_room_ids = config.get("ban_lists", [])
+        self.rooms_to_lists = {}  # type: Dict[str, BanList]
+        self.hs = hs
+
+        # Now we build the ban lists so we can match them
+        self.build_lists()
+
+    def build_lists(self):
+        for room_id in self.list_room_ids:
+            self.build_list(room_id)
+
+    def build_list(self, room_id):
+        logger.info("Rebuilding ban list for %s" % (room_id))
+        self.get_list_for_room(room_id).build()
+
+    def get_list_for_room(self, room_id):
+        if room_id not in self.rooms_to_lists:
+            self.rooms_to_lists[room_id] = BanList(hs=self.hs, room_id=room_id)
+        return self.rooms_to_lists[room_id]
+
+    def is_user_banned(self, user_id):
+        for room_id in self.rooms_to_lists:
+            ban_list = self.rooms_to_lists[room_id]
+            for rule in ban_list.user_rules:
+                if rule.matches(user_id):
+                    return rule.action == RECOMMENDATION_BAN
+        return False
+
+    def is_server_banned(self, server_name):
+        for room_id in self.rooms_to_lists:
+            ban_list = self.rooms_to_lists[room_id]
+            for rule in ban_list.server_rules:
+                if rule.matches(server_name):
+                    return rule.action == RECOMMENDATION_BAN
+        return False
+
+    # --- spam checker interface below here ---
 
     def check_event_for_spam(self, event):
-        return False # not spam
+        room_id = event.get("room_id", "")
+        event_type = event.get("type", "")
+        state_key = event.get("state_key", None)
+
+        # Rebuild the rules if there's an event for our ban lists
+        if state_key is not None and event_type in ALL_RULE_TYPES and room_id in self.list_room_ids:
+            logger.info("Received ban list event - updating list")
+            self.get_list_for_room(room_id).build(with_event=event)
+            return False  # Ban list updates aren't spam
+
+        if not self.block_messages:
+            return False  # not spam (we aren't blocking messages)
+
+        sender = UserID.from_string(event.get("sender", ""))
+        if self.is_user_banned(sender.to_string()):
+            return True
+        if self.is_server_banned(sender.domain):
+            return True
+
+        return False  # not spam (as far as we're concerned)
 
     def user_may_invite(self, inviter_user_id, invitee_user_id, room_id):
-        return True # allowed
+        if not self.block_invites:
+            return True  # allowed (we aren't blocking invites)
+
+        sender = UserID.from_string(inviter_user_id)
+        if self.is_user_banned(sender.to_string()):
+            return False
+        if self.is_server_banned(sender.domain):
+            return False
+
+        return True  # allowed (as far as we're concerned)
 
     def user_may_create_room(self, user_id):
         return True  # allowed

synapse_antispam/mjolnir/ban_list.py

@@ -0,0 +1,80 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 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.
+
+import logging
+from .list_rule import ListRule, ALL_RULE_TYPES, USER_RULE_TYPES, SERVER_RULE_TYPES, ROOM_RULE_TYPES
+from twisted.internet import defer
+from synapse.storage.state import StateFilter
+
+logger = logging.getLogger("synapse.contrib." + __name__)
+
+class BanList(object):
+    def __init__(self, hs, room_id):
+        self.hs = hs
+        self.room_id = room_id
+        self.server_rules = []
+        self.user_rules = []
+        self.room_rules = []
+        self.build()
+
+    @defer.inlineCallbacks
+    def build(self, with_event=None):
+        events = yield self.get_relevant_state_events()
+        if with_event is not None:
+            events = [*events, with_event]
+        self.server_rules = []
+        self.user_rules = []
+        self.room_rules = []
+        for event in events:
+            event_type = event.get("type", "")
+            state_key = event.get("state_key", "")
+            content = event.get("content", {})
+            if state_key is None:
+                continue  # Some message event got in here?
+
+            # Skip over events which are replaced by with_event. We do this
+            # to ensure that when we rebuild the list we're using updated rules.
+            if with_event is not None:
+                w_event_type = with_event.get("type", "")
+                w_state_key = with_event.get("state_key", "")
+                w_event_id = with_event.event_id
+                event_id = event.event_id
+                if w_event_type == event_type and w_state_key == state_key and w_event_id != event_id:
+                    continue
+
+            entity = content.get("entity", None)
+            recommendation = content.get("recommendation", None)
+            reason = content.get("reason", None)
+            if entity is None or recommendation is None or reason is None:
+                continue  # invalid event
+
+            logger.info("Adding rule %s/%s with action %s" % (event_type, entity, recommendation))
+            rule = ListRule(entity=entity, action=recommendation, reason=reason, kind=event_type)
+            if event_type in USER_RULE_TYPES:
+                self.user_rules.append(rule)
+            elif event_type in ROOM_RULE_TYPES:
+                self.room_rules.append(rule)
+            elif event_type in SERVER_RULE_TYPES:
+                self.server_rules.append(rule)
+
+    @defer.inlineCallbacks
+    def get_relevant_state_events(self):
+        store = self.hs.get_datastore()
+        ev_filter = StateFilter.from_types([(t, None) for t in ALL_RULE_TYPES])
+        state_ids = yield store.get_filtered_current_state_ids(
+            room_id=self.room_id, state_filter=ev_filter
+        )
+        state = yield store.get_events(state_ids.values())
+        return state.values()

synapse_antispam/mjolnir/list_rule.py

@@ -0,0 +1,52 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 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 synapse.util import glob_to_regex
+
+RECOMMENDATION_BAN = "m.ban"
+RECOMMENDATION_BAN_TYPES = [RECOMMENDATION_BAN, "org.matrix.mjolnir.ban"]
+
+RULE_USER = "m.room.rule.user"
+RULE_ROOM = "m.room.rule.room"
+RULE_SERVER = "m.room.rule.server"
+USER_RULE_TYPES = [RULE_USER, "org.matrix.mjolnir.rule.user"]
+ROOM_RULE_TYPES = [RULE_ROOM, "org.matrix.mjolnir.rule.room"]
+SERVER_RULE_TYPES = [RULE_SERVER, "org.matrix.mjolnir.rule.server"]
+ALL_RULE_TYPES = [*USER_RULE_TYPES, *ROOM_RULE_TYPES, *SERVER_RULE_TYPES]
+
+def recommendation_to_stable(recommendation):
+    if recommendation in RECOMMENDATION_BAN_TYPES:
+        return RECOMMENDATION_BAN
+    return None
+
+def rule_type_to_stable(rule):
+    if rule in USER_RULE_TYPES:
+        return RULE_USER
+    if rule in ROOM_RULE_TYPES:
+        return RULE_ROOM
+    if rule in SERVER_RULE_TYPES:
+        return RULE_SERVER
+    return None
+
+class ListRule(object):
+    def __init__(self, entity, action, reason, kind):
+        self.entity = entity
+        self.regex = glob_to_regex(entity)
+        self.action = recommendation_to_stable(action)
+        self.reason = reason
+        self.kind = rule_type_to_stable(kind)
+
+    def matches(self, victim):
+        return self.regex.match(victim)