# Copyright 2014 - 2016 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. import logging from typing import TYPE_CHECKING, Optional, Tuple import pymacaroons from netaddr import IPAddress from twisted.web.server import Request from synapse import event_auth from synapse.api.auth_blocking import AuthBlocking from synapse.api.constants import EventTypes, HistoryVisibility, Membership from synapse.api.errors import ( AuthError, Codes, InvalidClientTokenError, MissingClientTokenError, ) from synapse.appservice import ApplicationService from synapse.events import EventBase from synapse.http import get_request_user_agent from synapse.http.site import SynapseRequest from synapse.logging import opentracing as opentracing from synapse.storage.databases.main.registration import TokenLookupResult from synapse.types import Requester, StateMap, UserID, create_requester from synapse.util.caches.lrucache import LruCache from synapse.util.macaroons import get_value_from_macaroon, satisfy_expiry if TYPE_CHECKING: from synapse.server import HomeServer logger = logging.getLogger(__name__) # guests always get this device id. GUEST_DEVICE_ID = "guest_device" class _InvalidMacaroonException(Exception): pass class Auth: """ This class contains functions for authenticating users of our client-server API. """ def __init__(self, hs: "HomeServer"): self.hs = hs self.clock = hs.get_clock() self.store = hs.get_datastore() self.state = hs.get_state_handler() self.token_cache: LruCache[str, Tuple[str, bool]] = LruCache( 10000, "token_cache" ) self._auth_blocking = AuthBlocking(self.hs) self._account_validity_enabled = ( hs.config.account_validity.account_validity_enabled ) self._track_appservice_user_ips = hs.config.track_appservice_user_ips self._macaroon_secret_key = hs.config.macaroon_secret_key self._force_tracing_for_users = hs.config.tracing.force_tracing_for_users async def check_user_in_room( self, room_id: str, user_id: str, current_state: Optional[StateMap[EventBase]] = None, allow_departed_users: bool = False, ) -> EventBase: """Check if the user is in the room, or was at some point. Args: room_id: The room to check. user_id: The user to check. current_state: 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. allow_departed_users: if True, accept users that were previously members but have now departed. Raises: AuthError if the user is/was not in the room. Returns: 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 = await self.state.get_current_state( room_id=room_id, event_type=EventTypes.Member, state_key=user_id ) if member: membership = member.membership if membership == Membership.JOIN: return member # XXX this looks totally bogus. Why do we not allow users who have been banned, # or those who were members previously and have been re-invited? if allow_departed_users and membership == Membership.LEAVE: forgot = await self.store.did_forget(user_id, room_id) if not forgot: return member raise AuthError(403, "User %s not in room %s" % (user_id, room_id)) async def get_user_by_req( self, request: SynapseRequest, allow_guest: bool = False, rights: str = "access", allow_expired: bool = False, ) -> Requester: """Get a registered user's ID. Args: request: An HTTP request with an access_token query parameter. allow_guest: If False, will raise an AuthError if the user making the request is a guest. rights: The operation being performed; the access token must allow this allow_expired: If True, allow the request through even if the account is expired, or session token lifetime has ended. Note that /login will deliver access tokens regardless of expiration. Returns: Resolves to the requester Raises: InvalidClientCredentialsError if no user by that token exists or the token is invalid. AuthError if access is denied for the user in the access token """ try: ip_addr = request.getClientIP() user_agent = get_request_user_agent(request) access_token = self.get_access_token_from_request(request) user_id, app_service = await self._get_appservice_user_id(request) if user_id and app_service: if ip_addr and self._track_appservice_user_ips: await self.store.insert_client_ip( user_id=user_id, access_token=access_token, ip=ip_addr, user_agent=user_agent, device_id="dummy-device", # stubbed ) requester = create_requester(user_id, app_service=app_service) request.requester = user_id if user_id in self._force_tracing_for_users: opentracing.force_tracing() opentracing.set_tag("authenticated_entity", user_id) opentracing.set_tag("user_id", user_id) opentracing.set_tag("appservice_id", app_service.id) return requester user_info = await self.get_user_by_access_token( access_token, rights, allow_expired=allow_expired ) token_id = user_info.token_id is_guest = user_info.is_guest shadow_banned = user_info.shadow_banned # Deny the request if the user account has expired. if self._account_validity_enabled and not allow_expired: if await self.store.is_account_expired( user_info.user_id, self.clock.time_msec() ): raise AuthError( 403, "User account has expired", errcode=Codes.EXPIRED_ACCOUNT ) device_id = user_info.device_id if access_token and ip_addr: await self.store.insert_client_ip( user_id=user_info.token_owner, access_token=access_token, ip=ip_addr, user_agent=user_agent, device_id=device_id, ) if is_guest and not allow_guest: raise AuthError( 403, "Guest access not allowed", errcode=Codes.GUEST_ACCESS_FORBIDDEN, ) # Mark the token as used. This is used to invalidate old refresh # tokens after some time. if not user_info.token_used and token_id is not None: await self.store.mark_access_token_as_used(token_id) requester = create_requester( user_info.user_id, token_id, is_guest, shadow_banned, device_id, app_service=app_service, authenticated_entity=user_info.token_owner, ) request.requester = requester if user_info.token_owner in self._force_tracing_for_users: opentracing.force_tracing() opentracing.set_tag("authenticated_entity", user_info.token_owner) opentracing.set_tag("user_id", user_info.user_id) if device_id: opentracing.set_tag("device_id", device_id) return requester except KeyError: raise MissingClientTokenError() async def validate_appservice_can_control_user_id( self, app_service: ApplicationService, user_id: str ): """Validates that the app service is allowed to control the given user. Args: app_service: The app service that controls the user user_id: The author MXID that the app service is controlling Raises: AuthError: If the application service is not allowed to control the user (user namespace regex does not match, wrong homeserver, etc) or if the user has not been registered yet. """ # It's ok if the app service is trying to use the sender from their registration if app_service.sender == user_id: pass # Check to make sure the app service is allowed to control the user elif not app_service.is_interested_in_user(user_id): raise AuthError( 403, "Application service cannot masquerade as this user (%s)." % user_id, ) # Check to make sure the user is already registered on the homeserver elif not (await self.store.get_user_by_id(user_id)): raise AuthError( 403, "Application service has not registered this user (%s)" % user_id ) async def _get_appservice_user_id( self, request: Request ) -> Tuple[Optional[str], Optional[ApplicationService]]: app_service = self.store.get_app_service_by_token( self.get_access_token_from_request(request) ) if app_service is None: return None, None if app_service.ip_range_whitelist: ip_address = IPAddress(request.getClientIP()) if ip_address not in app_service.ip_range_whitelist: return None, None # This will always be set by the time Twisted calls us. assert request.args is not None if b"user_id" not in request.args: return app_service.sender, app_service user_id = request.args[b"user_id"][0].decode("utf8") await self.validate_appservice_can_control_user_id(app_service, user_id) if app_service.sender == user_id: return app_service.sender, app_service return user_id, app_service async def get_user_by_access_token( self, token: str, rights: str = "access", allow_expired: bool = False, ) -> TokenLookupResult: """Validate access token and get user_id from it Args: token: The access token to get the user by rights: The operation being performed; the access token must allow this allow_expired: If False, raises an InvalidClientTokenError if the token is expired Raises: InvalidClientTokenError if a user by that token exists, but the token is expired InvalidClientCredentialsError if no user by that token exists or the token is invalid """ if rights == "access": # first look in the database r = await self.store.get_user_by_access_token(token) if r: valid_until_ms = r.valid_until_ms if ( not allow_expired and valid_until_ms is not None and valid_until_ms < self.clock.time_msec() ): # there was a valid access token, but it has expired. # soft-logout the user. raise InvalidClientTokenError( msg="Access token has expired", soft_logout=True ) return r # otherwise it needs to be a valid macaroon try: user_id, guest = self._parse_and_validate_macaroon(token, rights) if rights == "access": if not guest: # non-guest access tokens must be in the database logger.warning("Unrecognised access token - not in store.") raise InvalidClientTokenError() # Guest access tokens are not stored in the database (there can # only be one access token per guest, anyway). # # In order to prevent guest access tokens being used as regular # user access tokens (and hence getting around the invalidation # process), we look up the user id and check that it is indeed # a guest user. # # It would of course be much easier to store guest access # tokens in the database as well, but that would break existing # guest tokens. stored_user = await self.store.get_user_by_id(user_id) if not stored_user: raise InvalidClientTokenError("Unknown user_id %s" % user_id) if not stored_user["is_guest"]: raise InvalidClientTokenError( "Guest access token used for regular user" ) ret = TokenLookupResult( user_id=user_id, is_guest=True, # all guests get the same device id device_id=GUEST_DEVICE_ID, ) elif rights == "delete_pusher": # We don't store these tokens in the database ret = TokenLookupResult(user_id=user_id, is_guest=False) else: raise RuntimeError("Unknown rights setting %s", rights) return ret except ( _InvalidMacaroonException, pymacaroons.exceptions.MacaroonException, TypeError, ValueError, ) as e: logger.warning("Invalid macaroon in auth: %s %s", type(e), e) raise InvalidClientTokenError("Invalid macaroon passed.") def _parse_and_validate_macaroon( self, token: str, rights: str = "access" ) -> Tuple[str, bool]: """Takes a macaroon and tries to parse and validate it. This is cached if and only if rights == access and there isn't an expiry. On invalid macaroon raises _InvalidMacaroonException Returns: (user_id, is_guest) """ if rights == "access": cached = self.token_cache.get(token, None) if cached: return cached try: macaroon = pymacaroons.Macaroon.deserialize(token) except Exception: # deserialize can throw more-or-less anything # doesn't look like a macaroon: treat it as an opaque token which # must be in the database. # TODO: it would be nice to get rid of this, but apparently some # people use access tokens which aren't macaroons raise _InvalidMacaroonException() try: user_id = get_value_from_macaroon(macaroon, "user_id") guest = False for caveat in macaroon.caveats: if caveat.caveat_id == "guest = true": guest = True self.validate_macaroon(macaroon, rights, user_id=user_id) except ( pymacaroons.exceptions.MacaroonException, KeyError, TypeError, ValueError, ): raise InvalidClientTokenError("Invalid macaroon passed.") if rights == "access": self.token_cache[token] = (user_id, guest) return user_id, guest def validate_macaroon( self, macaroon: pymacaroons.Macaroon, type_string: str, user_id: str ) -> None: """ validate that a Macaroon is understood by and was signed by this server. Args: macaroon: The macaroon to validate type_string: The kind of token required (e.g. "access", "delete_pusher") user_id: The user_id required """ v = pymacaroons.Verifier() # the verifier runs a test for every caveat on the macaroon, to check # that it is met for the current request. Each caveat must match at # least one of the predicates specified by satisfy_exact or # specify_general. v.satisfy_exact("gen = 1") v.satisfy_exact("type = " + type_string) v.satisfy_exact("user_id = %s" % user_id) v.satisfy_exact("guest = true") satisfy_expiry(v, self.clock.time_msec) # access_tokens include a nonce for uniqueness: any value is acceptable v.satisfy_general(lambda c: c.startswith("nonce = ")) v.verify(macaroon, self._macaroon_secret_key) def get_appservice_by_req(self, request: SynapseRequest) -> ApplicationService: token = self.get_access_token_from_request(request) service = self.store.get_app_service_by_token(token) if not service: logger.warning("Unrecognised appservice access token.") raise InvalidClientTokenError() request.requester = create_requester(service.sender, app_service=service) return service async def is_server_admin(self, user: UserID) -> bool: """Check if the given user is a local server admin. Args: user: user to check Returns: True if the user is an admin """ return await self.store.is_server_admin(user) async def check_can_change_room_list(self, room_id: str, user: UserID) -> bool: """Determine whether the user is allowed to edit the room's entry in the published room list. Args: room_id user """ is_admin = await self.is_server_admin(user) if is_admin: return True user_id = user.to_string() await self.check_user_in_room(room_id, user_id) # We currently require the user is a "moderator" in the room. We do this # by checking if they would (theoretically) be able to change the # m.room.canonical_alias events power_level_event = await self.state.get_current_state( room_id, EventTypes.PowerLevels, "" ) auth_events = {} if power_level_event: auth_events[(EventTypes.PowerLevels, "")] = power_level_event send_level = event_auth.get_send_level( EventTypes.CanonicalAlias, "", power_level_event ) user_level = event_auth.get_user_power_level(user_id, auth_events) return user_level >= send_level @staticmethod def has_access_token(request: Request) -> bool: """Checks if the request has an access_token. Returns: False if no access_token was given, True otherwise. """ # This will always be set by the time Twisted calls us. assert request.args is not None query_params = request.args.get(b"access_token") auth_headers = request.requestHeaders.getRawHeaders(b"Authorization") return bool(query_params) or bool(auth_headers) @staticmethod def get_access_token_from_request(request: Request) -> str: """Extracts the access_token from the request. Args: request: The http request. Returns: The access_token Raises: MissingClientTokenError: If there isn't a single access_token in the request """ # This will always be set by the time Twisted calls us. assert request.args is not None auth_headers = request.requestHeaders.getRawHeaders(b"Authorization") query_params = request.args.get(b"access_token") if auth_headers: # Try the get the access_token from a "Authorization: Bearer" # header if query_params is not None: raise MissingClientTokenError( "Mixing Authorization headers and access_token query parameters." ) if len(auth_headers) > 1: raise MissingClientTokenError("Too many Authorization headers.") parts = auth_headers[0].split(b" ") if parts[0] == b"Bearer" and len(parts) == 2: return parts[1].decode("ascii") else: raise MissingClientTokenError("Invalid Authorization header.") else: # Try to get the access_token from the query params. if not query_params: raise MissingClientTokenError() return query_params[0].decode("ascii") async def check_user_in_room_or_world_readable( self, room_id: str, user_id: str, allow_departed_users: bool = False ) -> Tuple[str, Optional[str]]: """Checks that the user is or was in the room or the room is world readable. If it isn't then an exception is raised. Args: room_id: room to check user_id: user to check allow_departed_users: if True, accept users that were previously members but have now departed Returns: Resolves to the current membership of the user in the room and the membership event ID of the user. If the user is not in the room and never has been, then `(Membership.JOIN, None)` is returned. """ try: # check_user_in_room will return the most recent membership # event for the user if: # * The user is a non-guest user, and was ever in the room # * The user is a guest user, and has joined the room # else it will throw. member_event = await self.check_user_in_room( room_id, user_id, allow_departed_users=allow_departed_users ) return member_event.membership, member_event.event_id except AuthError: visibility = await self.state.get_current_state( room_id, EventTypes.RoomHistoryVisibility, "" ) if ( visibility and visibility.content.get("history_visibility") == HistoryVisibility.WORLD_READABLE ): return Membership.JOIN, None raise AuthError( 403, "User %s not in room %s, and room previews are disabled" % (user_id, room_id), ) async def check_auth_blocking(self, *args, **kwargs) -> None: await self._auth_blocking.check_auth_blocking(*args, **kwargs)