# -*- coding: utf-8 -*- # Copyright 2014, 2015 OpenMarket Ltd # # 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. """This module contains classes for authenticating the user.""" from signedjson.key import decode_verify_key_bytes from signedjson.sign import verify_signed_json, SignatureVerifyException from twisted.internet import defer from synapse.api.constants import EventTypes, Membership, JoinRules from synapse.api.errors import AuthError, Codes, SynapseError from synapse.types import RoomID, UserID, EventID from synapse.util.logutils import log_function from synapse.util import third_party_invites from unpaddedbase64 import decode_base64 import logging import pymacaroons logger = logging.getLogger(__name__) AuthEventTypes = ( EventTypes.Create, EventTypes.Member, EventTypes.PowerLevels, EventTypes.JoinRules, EventTypes.RoomHistoryVisibility, EventTypes.ThirdPartyInvite, ) class Auth(object): def __init__(self, hs): self.hs = hs self.store = hs.get_datastore() self.state = hs.get_state_handler() self.TOKEN_NOT_FOUND_HTTP_STATUS = 401 self._KNOWN_CAVEAT_PREFIXES = set([ "gen = ", "type = ", "time < ", "user_id = ", ]) def check(self, event, auth_events): """ Checks if this event is correctly authed. Args: event: the event being checked. auth_events (dict: event-key -> event): the existing room state. Returns: True if the auth checks pass. """ try: if not hasattr(event, "room_id"): raise AuthError(500, "Event has no room_id: %s" % event) if auth_events is None: # Oh, we don't know what the state of the room was, so we # are trusting that this is allowed (at least for now) logger.warn("Trusting event: %s", event.event_id) return True if event.type == EventTypes.Create: # FIXME return True creation_event = auth_events.get((EventTypes.Create, ""), None) if not creation_event: raise SynapseError( 403, "Room %r does not exist" % (event.room_id,) ) creating_domain = RoomID.from_string(event.room_id).domain originating_domain = UserID.from_string(event.sender).domain if creating_domain != originating_domain: if not self.can_federate(event, auth_events): raise AuthError( 403, "This room has been marked as unfederatable." ) # FIXME: Temp hack if event.type == EventTypes.Aliases: return True logger.debug( "Auth events: %s", [a.event_id for a in auth_events.values()] ) if event.type == EventTypes.Member: allowed = self.is_membership_change_allowed( event, auth_events ) if allowed: logger.debug("Allowing! %s", event) else: logger.debug("Denying! %s", event) return allowed self.check_event_sender_in_room(event, auth_events) self._can_send_event(event, auth_events) if event.type == EventTypes.PowerLevels: self._check_power_levels(event, auth_events) if event.type == EventTypes.Redaction: self.check_redaction(event, auth_events) logger.debug("Allowing! %s", event) except AuthError as e: logger.info( "Event auth check failed on event %s with msg: %s", event, e.msg ) logger.info("Denying! %s", event) raise @defer.inlineCallbacks def check_joined_room(self, room_id, user_id, current_state=None): """Check if the user is currently joined in the room Args: room_id(str): The room to check. user_id(str): The user to check. current_state(dict): Optional map of the current state of the room. If provided then that map is used to check whether they are a member of the room. Otherwise the current membership is loaded from the database. Raises: AuthError if the user is not in the room. Returns: A deferred membership event for the user if the user is in the room. """ if current_state: member = current_state.get( (EventTypes.Member, user_id), None ) else: member = yield self.state.get_current_state( room_id=room_id, event_type=EventTypes.Member, state_key=user_id ) self._check_joined_room(member, user_id, room_id) defer.returnValue(member) @defer.inlineCallbacks def check_user_was_in_room(self, room_id, user_id, current_state=None): """Check if the user was in the room at some point. Args: room_id(str): The room to check. user_id(str): The user to check. current_state(dict): Optional map of the current state of the room. If provided then that map is used to check whether they are a member of the room. Otherwise the current membership is loaded from the database. Raises: AuthError if the user was never in the room. Returns: A deferred membership event for the user if the user was in the room. This will be the join event if they are currently joined to the room. This will be the leave event if they have left the room. """ if current_state: member = current_state.get( (EventTypes.Member, user_id), None ) else: member = yield self.state.get_current_state( room_id=room_id, event_type=EventTypes.Member, state_key=user_id ) membership = member.membership if member else None if membership not in (Membership.JOIN, Membership.LEAVE): raise AuthError(403, "User %s not in room %s" % ( user_id, room_id )) defer.returnValue(member) @defer.inlineCallbacks def check_host_in_room(self, room_id, host): curr_state = yield self.state.get_current_state(room_id) for event in curr_state.values(): if event.type == EventTypes.Member: try: if UserID.from_string(event.state_key).domain != host: continue except: logger.warn("state_key not user_id: %s", event.state_key) continue if event.content["membership"] == Membership.JOIN: defer.returnValue(True) defer.returnValue(False) def check_event_sender_in_room(self, event, auth_events): key = (EventTypes.Member, event.user_id, ) member_event = auth_events.get(key) return self._check_joined_room( member_event, event.user_id, event.room_id ) def _check_joined_room(self, member, user_id, room_id): if not member or member.membership != Membership.JOIN: raise AuthError(403, "User %s not in room %s (%s)" % ( user_id, room_id, repr(member) )) def can_federate(self, event, auth_events): creation_event = auth_events.get((EventTypes.Create, "")) return creation_event.content.get("m.federate", True) is True @log_function def is_membership_change_allowed(self, event, auth_events): membership = event.content["membership"] # Check if this is the room creator joining: if len(event.prev_events) == 1 and Membership.JOIN == membership: # Get room creation event: key = (EventTypes.Create, "", ) create = auth_events.get(key) if create and event.prev_events[0][0] == create.event_id: if create.content["creator"] == event.state_key: return True target_user_id = event.state_key creating_domain = RoomID.from_string(event.room_id).domain target_domain = UserID.from_string(target_user_id).domain if creating_domain != target_domain: if not self.can_federate(event, auth_events): raise AuthError( 403, "This room has been marked as unfederatable." ) # get info about the caller key = (EventTypes.Member, event.user_id, ) caller = auth_events.get(key) caller_in_room = caller and caller.membership == Membership.JOIN caller_invited = caller and caller.membership == Membership.INVITE # get info about the target key = (EventTypes.Member, target_user_id, ) target = auth_events.get(key) target_in_room = target and target.membership == Membership.JOIN target_banned = target and target.membership == Membership.BAN key = (EventTypes.JoinRules, "", ) join_rule_event = auth_events.get(key) if join_rule_event: join_rule = join_rule_event.content.get( "join_rule", JoinRules.INVITE ) else: join_rule = JoinRules.INVITE user_level = self._get_user_power_level(event.user_id, auth_events) target_level = self._get_user_power_level( target_user_id, auth_events ) # FIXME (erikj): What should we do here as the default? ban_level = self._get_named_level(auth_events, "ban", 50) logger.debug( "is_membership_change_allowed: %s", { "caller_in_room": caller_in_room, "caller_invited": caller_invited, "target_banned": target_banned, "target_in_room": target_in_room, "membership": membership, "join_rule": join_rule, "target_user_id": target_user_id, "event.user_id": event.user_id, } ) if Membership.JOIN != membership: if (caller_invited and Membership.LEAVE == membership and target_user_id == event.user_id): return True if not caller_in_room: # caller isn't joined raise AuthError( 403, "%s not in room %s." % (event.user_id, event.room_id,) ) if Membership.INVITE == membership: # TODO (erikj): We should probably handle this more intelligently # PRIVATE join rules. # Invites are valid iff caller is in the room and target isn't. if target_banned: raise AuthError( 403, "%s is banned from the room" % (target_user_id,) ) elif target_in_room: # the target is already in the room. raise AuthError(403, "%s is already in the room." % target_user_id) else: invite_level = self._get_named_level(auth_events, "invite", 0) if user_level < invite_level: raise AuthError( 403, "You cannot invite user %s." % target_user_id ) elif Membership.JOIN == membership: # Joins are valid iff caller == target and they were: # invited: They are accepting the invitation # joined: It's a NOOP if event.user_id != target_user_id: raise AuthError(403, "Cannot force another user to join.") elif target_banned: raise AuthError(403, "You are banned from this room") elif join_rule == JoinRules.PUBLIC: pass elif join_rule == JoinRules.INVITE: if not caller_in_room and not caller_invited: if not self._verify_third_party_invite(event, auth_events): raise AuthError(403, "You are not invited to this room.") else: # TODO (erikj): may_join list # TODO (erikj): private rooms raise AuthError(403, "You are not allowed to join this room") elif Membership.LEAVE == membership: # TODO (erikj): Implement kicks. if target_banned and user_level < ban_level: raise AuthError( 403, "You cannot unban user &s." % (target_user_id,) ) elif target_user_id != event.user_id: kick_level = self._get_named_level(auth_events, "kick", 50) if user_level < kick_level or user_level <= target_level: raise AuthError( 403, "You cannot kick user %s." % target_user_id ) elif Membership.BAN == membership: if user_level < ban_level or user_level <= target_level: raise AuthError(403, "You don't have permission to ban") else: raise AuthError(500, "Unknown membership %s" % membership) return True def _verify_third_party_invite(self, event, auth_events): """ Validates that the join event is authorized by a previous third-party invite. Checks that the public key, and keyserver, match those in the invite, and that the join event has a signature issued using that public key. Args: event: The m.room.member join event being validated. auth_events: All relevant previous context events which may be used for authorization decisions. Return: True if the event fulfills the expectations of a previous third party invite event. """ if not third_party_invites.join_has_third_party_invite(event.content): return False join_third_party_invite = event.content["third_party_invite"] token = join_third_party_invite["token"] invite_event = auth_events.get( (EventTypes.ThirdPartyInvite, token,) ) if not invite_event: logger.info("Failing 3pid invite because no invite found for token %s", token) return False try: public_key = join_third_party_invite["public_key"] key_validity_url = join_third_party_invite["key_validity_url"] if invite_event.content["public_key"] != public_key: logger.info( "Failing 3pid invite because public key invite: %s != join: %s", invite_event.content["public_key"], public_key ) return False if invite_event.content["key_validity_url"] != key_validity_url: logger.info( "Failing 3pid invite because key_validity_url invite: %s != join: %s", invite_event.content["key_validity_url"], key_validity_url ) return False signed = join_third_party_invite["signed"] if signed["mxid"] != event.user_id: return False if signed["token"] != token: return False for server, signature_block in signed["signatures"].items(): for key_name, encoded_signature in signature_block.items(): if not key_name.startswith("ed25519:"): return False verify_key = decode_verify_key_bytes( key_name, decode_base64(public_key) ) verify_signed_json(signed, server, verify_key) return True return False except (KeyError, SignatureVerifyException,): return False def _get_power_level_event(self, auth_events): key = (EventTypes.PowerLevels, "", ) return auth_events.get(key) def _get_user_power_level(self, user_id, auth_events): power_level_event = self._get_power_level_event(auth_events) if power_level_event: level = power_level_event.content.get("users", {}).get(user_id) if not level: level = power_level_event.content.get("users_default", 0) if level is None: return 0 else: return int(level) else: key = (EventTypes.Create, "", ) create_event = auth_events.get(key) if (create_event is not None and create_event.content["creator"] == user_id): return 100 else: return 0 def _get_named_level(self, auth_events, name, default): power_level_event = self._get_power_level_event(auth_events) if not power_level_event: return default level = power_level_event.content.get(name, None) if level is not None: return int(level) else: return default @defer.inlineCallbacks def get_user_by_req(self, request): """ Get a registered user's ID. Args: request - An HTTP request with an access_token query parameter. Returns: tuple of: UserID (str) Access token ID (str) Raises: AuthError if no user by that token exists or the token is invalid. """ # Can optionally look elsewhere in the request (e.g. headers) try: access_token = request.args["access_token"][0] # Check for application service tokens with a user_id override try: app_service = yield self.store.get_app_service_by_token( access_token ) if not app_service: raise KeyError user_id = app_service.sender if "user_id" in request.args: user_id = request.args["user_id"][0] if not app_service.is_interested_in_user(user_id): raise AuthError( 403, "Application service cannot masquerade as this user." ) if not user_id: raise KeyError request.authenticated_entity = user_id defer.returnValue((UserID.from_string(user_id), "")) return except KeyError: pass # normal users won't have the user_id query parameter set. user_info = yield self._get_user_by_access_token(access_token) user = user_info["user"] token_id = user_info["token_id"] ip_addr = self.hs.get_ip_from_request(request) user_agent = request.requestHeaders.getRawHeaders( "User-Agent", default=[""] )[0] if user and access_token and ip_addr: self.store.insert_client_ip( user=user, access_token=access_token, ip=ip_addr, user_agent=user_agent ) request.authenticated_entity = user.to_string() defer.returnValue((user, token_id,)) except KeyError: raise AuthError( self.TOKEN_NOT_FOUND_HTTP_STATUS, "Missing access token.", errcode=Codes.MISSING_TOKEN ) @defer.inlineCallbacks def _get_user_by_access_token(self, token): """ Get a registered user's ID. Args: token (str): The access token to get the user by. Returns: dict : dict that includes the user and the ID of their access token. Raises: AuthError if no user by that token exists or the token is invalid. """ try: ret = yield self._get_user_from_macaroon(token) except AuthError: # TODO(daniel): Remove this fallback when all existing access tokens # have been re-issued as macaroons. ret = yield self._look_up_user_by_access_token(token) defer.returnValue(ret) @defer.inlineCallbacks def _get_user_from_macaroon(self, macaroon_str): try: macaroon = pymacaroons.Macaroon.deserialize(macaroon_str) self._validate_macaroon(macaroon) user_prefix = "user_id = " for caveat in macaroon.caveats: if caveat.caveat_id.startswith(user_prefix): user = UserID.from_string(caveat.caveat_id[len(user_prefix):]) # This codepath exists so that we can actually return a # token ID, because we use token IDs in place of device # identifiers throughout the codebase. # TODO(daniel): Remove this fallback when device IDs are # properly implemented. ret = yield self._look_up_user_by_access_token(macaroon_str) if ret["user"] != user: logger.error( "Macaroon user (%s) != DB user (%s)", user, ret["user"] ) raise AuthError( self.TOKEN_NOT_FOUND_HTTP_STATUS, "User mismatch in macaroon", errcode=Codes.UNKNOWN_TOKEN ) defer.returnValue(ret) raise AuthError( self.TOKEN_NOT_FOUND_HTTP_STATUS, "No user caveat in macaroon", errcode=Codes.UNKNOWN_TOKEN ) except (pymacaroons.exceptions.MacaroonException, TypeError, ValueError): raise AuthError( self.TOKEN_NOT_FOUND_HTTP_STATUS, "Invalid macaroon passed.", errcode=Codes.UNKNOWN_TOKEN ) def _validate_macaroon(self, macaroon): v = pymacaroons.Verifier() v.satisfy_exact("gen = 1") v.satisfy_exact("type = access") v.satisfy_general(lambda c: c.startswith("user_id = ")) v.satisfy_general(self._verify_expiry) v.verify(macaroon, self.hs.config.macaroon_secret_key) v = pymacaroons.Verifier() v.satisfy_general(self._verify_recognizes_caveats) v.verify(macaroon, self.hs.config.macaroon_secret_key) def _verify_expiry(self, caveat): prefix = "time < " if not caveat.startswith(prefix): return False # TODO(daniel): Enable expiry check when clients actually know how to # refresh tokens. (And remember to enable the tests) return True expiry = int(caveat[len(prefix):]) now = self.hs.get_clock().time_msec() return now < expiry def _verify_recognizes_caveats(self, caveat): first_space = caveat.find(" ") if first_space < 0: return False second_space = caveat.find(" ", first_space + 1) if second_space < 0: return False return caveat[:second_space + 1] in self._KNOWN_CAVEAT_PREFIXES @defer.inlineCallbacks def _look_up_user_by_access_token(self, token): ret = yield self.store.get_user_by_access_token(token) if not ret: raise AuthError( self.TOKEN_NOT_FOUND_HTTP_STATUS, "Unrecognised access token.", errcode=Codes.UNKNOWN_TOKEN ) user_info = { "user": UserID.from_string(ret.get("name")), "token_id": ret.get("token_id", None), } defer.returnValue(user_info) @defer.inlineCallbacks def get_appservice_by_req(self, request): try: token = request.args["access_token"][0] service = yield self.store.get_app_service_by_token(token) if not service: raise AuthError( self.TOKEN_NOT_FOUND_HTTP_STATUS, "Unrecognised access token.", errcode=Codes.UNKNOWN_TOKEN ) request.authenticated_entity = service.sender defer.returnValue(service) except KeyError: raise AuthError( self.TOKEN_NOT_FOUND_HTTP_STATUS, "Missing access token." ) def is_server_admin(self, user): return self.store.is_server_admin(user) @defer.inlineCallbacks def add_auth_events(self, builder, context): auth_ids = self.compute_auth_events(builder, context.current_state) auth_events_entries = yield self.store.add_event_hashes( auth_ids ) builder.auth_events = auth_events_entries def compute_auth_events(self, event, current_state): if event.type == EventTypes.Create: return [] auth_ids = [] key = (EventTypes.PowerLevels, "", ) power_level_event = current_state.get(key) if power_level_event: auth_ids.append(power_level_event.event_id) key = (EventTypes.JoinRules, "", ) join_rule_event = current_state.get(key) key = (EventTypes.Member, event.user_id, ) member_event = current_state.get(key) key = (EventTypes.Create, "", ) create_event = current_state.get(key) if create_event: auth_ids.append(create_event.event_id) if join_rule_event: join_rule = join_rule_event.content.get("join_rule") is_public = join_rule == JoinRules.PUBLIC if join_rule else False else: is_public = False if event.type == EventTypes.Member: e_type = event.content["membership"] if e_type in [Membership.JOIN, Membership.INVITE]: if join_rule_event: auth_ids.append(join_rule_event.event_id) if e_type == Membership.JOIN: if member_event and not is_public: auth_ids.append(member_event.event_id) if third_party_invites.join_has_third_party_invite(event.content): key = ( EventTypes.ThirdPartyInvite, event.content["third_party_invite"]["token"] ) invite = current_state.get(key) if invite: auth_ids.append(invite.event_id) else: if member_event: auth_ids.append(member_event.event_id) elif member_event: if member_event.content["membership"] == Membership.JOIN: auth_ids.append(member_event.event_id) return auth_ids @log_function def _can_send_event(self, event, auth_events): key = (EventTypes.PowerLevels, "", ) send_level_event = auth_events.get(key) send_level = None if send_level_event: send_level = send_level_event.content.get("events", {}).get( event.type ) if send_level is None: if hasattr(event, "state_key"): send_level = send_level_event.content.get( "state_default", 50 ) else: send_level = send_level_event.content.get( "events_default", 0 ) if send_level: send_level = int(send_level) else: send_level = 0 user_level = self._get_user_power_level(event.user_id, auth_events) if user_level < send_level: raise AuthError( 403, "You don't have permission to post that to the room. " + "user_level (%d) < send_level (%d)" % (user_level, send_level) ) # Check state_key if hasattr(event, "state_key"): if event.state_key.startswith("@"): if event.state_key != event.user_id: raise AuthError( 403, "You are not allowed to set others state" ) else: sender_domain = UserID.from_string( event.user_id ).domain if sender_domain != event.state_key: raise AuthError( 403, "You are not allowed to set others state" ) return True def check_redaction(self, event, auth_events): """Check whether the event sender is allowed to redact the target event. Returns: True if the the sender is allowed to redact the target event if the target event was created by them. False if the sender is allowed to redact the target event with no further checks. Raises: AuthError if the event sender is definitely not allowed to redact the target event. """ user_level = self._get_user_power_level(event.user_id, auth_events) redact_level = self._get_named_level(auth_events, "redact", 50) if user_level > redact_level: return False redacter_domain = EventID.from_string(event.event_id).domain redactee_domain = EventID.from_string(event.redacts).domain if redacter_domain == redactee_domain: return True raise AuthError( 403, "You don't have permission to redact events" ) def _check_power_levels(self, event, auth_events): user_list = event.content.get("users", {}) # Validate users for k, v in user_list.items(): try: UserID.from_string(k) except: raise SynapseError(400, "Not a valid user_id: %s" % (k,)) try: int(v) except: raise SynapseError(400, "Not a valid power level: %s" % (v,)) key = (event.type, event.state_key, ) current_state = auth_events.get(key) if not current_state: return user_level = self._get_user_power_level(event.user_id, auth_events) # Check other levels: levels_to_check = [ ("users_default", None), ("events_default", None), ("state_default", None), ("ban", None), ("redact", None), ("kick", None), ("invite", None), ] old_list = current_state.content.get("users") for user in set(old_list.keys() + user_list.keys()): levels_to_check.append( (user, "users") ) old_list = current_state.content.get("events") new_list = event.content.get("events") for ev_id in set(old_list.keys() + new_list.keys()): levels_to_check.append( (ev_id, "events") ) old_state = current_state.content new_state = event.content for level_to_check, dir in levels_to_check: old_loc = old_state new_loc = new_state if dir: old_loc = old_loc.get(dir, {}) new_loc = new_loc.get(dir, {}) if level_to_check in old_loc: old_level = int(old_loc[level_to_check]) else: old_level = None if level_to_check in new_loc: new_level = int(new_loc[level_to_check]) else: new_level = None if new_level is not None and old_level is not None: if new_level == old_level: continue if dir == "users" and level_to_check != event.user_id: if old_level == user_level: raise AuthError( 403, "You don't have permission to remove ops level equal " "to your own" ) if old_level > user_level or new_level > user_level: raise AuthError( 403, "You don't have permission to add ops level greater " "than your own" )