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SECURITY UPDATE: Prevent unauthorised users from setting state events in a room
when there is no `m.room.power_levels` event in force in the room. (PR #3397) Discussion around the Matrix Spec change proposal for this change can be followed at https://github.com/matrix-org/matrix-doc/issues/1304. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAABAgAGBQJbIop9AAoJEIofk9V1tejV9lsIAJVH0l5dXROmy1KH/zt16AUA CXa6Vv4Vyo6hKad/fZ81OZVRr5ChK/TvbIJVn/SA/muCfdoIFdxhT8eo/pXzO2UW zReuLsDhAg+gSvpNus37oWj2FVsAE1HYDZ60lfaapAdZnkFit68d5DQZjO6nZHHA YUXcU3GUwj0ZYuUzFzYKMLu6uNNasNkN8h6SS2lF7Bm4JaKDW+mFMfCyJwdIVSEh BGhHoVpXdxFysD9s6Mwxqrz3KKg1Jtp7idDkk0x2S2Eh+gxyiDQQokv0oQ3+0+HG sgy5Iz2t2CkpS02/j+LOvAZljTmnD0bXu3srGR+25StsoDFP038Am3bfQwtD190= =9jsT -----END PGP SIGNATURE----- Merge tag 'v0.31.2' SECURITY UPDATE: Prevent unauthorised users from setting state events in a room when there is no `m.room.power_levels` event in force in the room. (PR #3397) Discussion around the Matrix Spec change proposal for this change can be followed at https://github.com/matrix-org/matrix-doc/issues/1304.
This commit is contained in:
Richard van der Hoff
commit
53969e1960
@ -1,3 +1,12 @@
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Changes in synapse v0.31.2 (2018-06-14)
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=======================================
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SECURITY UPDATE: Prevent unauthorised users from setting state events in a room
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when there is no ``m.room.power_levels`` event in force in the room. (PR #3397)
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Discussion around the Matrix Spec change proposal for this change can be
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followed at https://github.com/matrix-org/matrix-doc/issues/1304.
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Changes in synapse v0.31.1 (2018-06-08)
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=======================================
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@ -1,5 +1,6 @@
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# -*- coding: utf-8 -*-
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# Copyright 2014-2016 OpenMarket Ltd
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# Copyright 2018 New Vector Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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@ -16,4 +17,4 @@
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""" This is a reference implementation of a Matrix home server.
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"""
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__version__ = "0.31.1"
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__version__ = "0.31.2"
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@ -655,7 +655,7 @@ class Auth(object):
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auth_events[(EventTypes.PowerLevels, "")] = power_level_event
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send_level = event_auth.get_send_level(
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EventTypes.Aliases, "", auth_events
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EventTypes.Aliases, "", power_level_event,
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)
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user_level = event_auth.get_user_power_level(user_id, auth_events)
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@ -34,9 +34,11 @@ def check(event, auth_events, do_sig_check=True, do_size_check=True):
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event: the event being checked.
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auth_events (dict: event-key -> event): the existing room state.
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Raises:
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AuthError if the checks fail
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Returns:
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True if the auth checks pass.
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if the auth checks pass.
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"""
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if do_size_check:
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_check_size_limits(event)
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@ -71,7 +73,7 @@ def check(event, auth_events, do_sig_check=True, do_size_check=True):
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# Oh, we don't know what the state of the room was, so we
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# are trusting that this is allowed (at least for now)
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logger.warn("Trusting event: %s", event.event_id)
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return True
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return
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if event.type == EventTypes.Create:
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room_id_domain = get_domain_from_id(event.room_id)
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@ -81,7 +83,8 @@ def check(event, auth_events, do_sig_check=True, do_size_check=True):
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"Creation event's room_id domain does not match sender's"
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)
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# FIXME
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return True
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logger.debug("Allowing! %s", event)
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return
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creation_event = auth_events.get((EventTypes.Create, ""), None)
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@ -118,7 +121,8 @@ def check(event, auth_events, do_sig_check=True, do_size_check=True):
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403,
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"Alias event's state_key does not match sender's domain"
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)
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return True
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logger.debug("Allowing! %s", event)
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return
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if logger.isEnabledFor(logging.DEBUG):
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logger.debug(
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@ -127,14 +131,9 @@ def check(event, auth_events, do_sig_check=True, do_size_check=True):
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)
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if event.type == EventTypes.Member:
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allowed = _is_membership_change_allowed(
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event, auth_events
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)
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if allowed:
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_is_membership_change_allowed(event, auth_events)
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logger.debug("Allowing! %s", event)
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else:
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logger.debug("Denying! %s", event)
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return allowed
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return
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_check_event_sender_in_room(event, auth_events)
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@ -153,7 +152,8 @@ def check(event, auth_events, do_sig_check=True, do_size_check=True):
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)
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)
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else:
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return True
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logger.debug("Allowing! %s", event)
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return
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_can_send_event(event, auth_events)
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@ -200,7 +200,7 @@ def _is_membership_change_allowed(event, auth_events):
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create = auth_events.get(key)
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if create and event.prev_events[0][0] == create.event_id:
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if create.content["creator"] == event.state_key:
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return True
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return
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target_user_id = event.state_key
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@ -265,13 +265,13 @@ def _is_membership_change_allowed(event, auth_events):
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raise AuthError(
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403, "%s is banned from the room" % (target_user_id,)
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)
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return True
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return
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if Membership.JOIN != membership:
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if (caller_invited
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and Membership.LEAVE == membership
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and target_user_id == event.user_id):
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return True
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return
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if not caller_in_room: # caller isn't joined
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raise AuthError(
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@ -334,8 +334,6 @@ def _is_membership_change_allowed(event, auth_events):
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else:
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raise AuthError(500, "Unknown membership %s" % membership)
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return True
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def _check_event_sender_in_room(event, auth_events):
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key = (EventTypes.Member, event.user_id, )
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@ -355,35 +353,46 @@ def _check_joined_room(member, user_id, room_id):
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))
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def get_send_level(etype, state_key, auth_events):
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key = (EventTypes.PowerLevels, "", )
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send_level_event = auth_events.get(key)
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send_level = None
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if send_level_event:
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send_level = send_level_event.content.get("events", {}).get(
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etype
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)
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def get_send_level(etype, state_key, power_levels_event):
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"""Get the power level required to send an event of a given type
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The federation spec [1] refers to this as "Required Power Level".
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https://matrix.org/docs/spec/server_server/unstable.html#definitions
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Args:
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etype (str): type of event
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state_key (str|None): state_key of state event, or None if it is not
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a state event.
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power_levels_event (synapse.events.EventBase|None): power levels event
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in force at this point in the room
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Returns:
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int: power level required to send this event.
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"""
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if power_levels_event:
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power_levels_content = power_levels_event.content
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else:
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power_levels_content = {}
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# see if we have a custom level for this event type
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send_level = power_levels_content.get("events", {}).get(etype)
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# otherwise, fall back to the state_default/events_default.
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if send_level is None:
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if state_key is not None:
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send_level = send_level_event.content.get(
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"state_default", 50
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)
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send_level = power_levels_content.get("state_default", 50)
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else:
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send_level = send_level_event.content.get(
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"events_default", 0
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)
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send_level = power_levels_content.get("events_default", 0)
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if send_level:
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send_level = int(send_level)
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else:
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send_level = 0
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return send_level
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return int(send_level)
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def _can_send_event(event, auth_events):
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power_levels_event = _get_power_level_event(auth_events)
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send_level = get_send_level(
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event.type, event.get("state_key", None), auth_events
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event.type, event.get("state_key"), power_levels_event,
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)
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user_level = get_user_power_level(event.user_id, auth_events)
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@ -524,13 +533,22 @@ def _check_power_levels(event, auth_events):
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def _get_power_level_event(auth_events):
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key = (EventTypes.PowerLevels, "", )
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return auth_events.get(key)
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return auth_events.get((EventTypes.PowerLevels, ""))
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def get_user_power_level(user_id, auth_events):
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power_level_event = _get_power_level_event(auth_events)
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"""Get a user's power level
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Args:
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user_id (str): user's id to look up in power_levels
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auth_events (dict[(str, str), synapse.events.EventBase]):
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state in force at this point in the room (or rather, a subset of
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it including at least the create event and power levels event.
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Returns:
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int: the user's power level in this room.
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"""
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power_level_event = _get_power_level_event(auth_events)
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if power_level_event:
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level = power_level_event.content.get("users", {}).get(user_id)
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if not level:
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@ -541,6 +559,11 @@ def get_user_power_level(user_id, auth_events):
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else:
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return int(level)
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else:
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# if there is no power levels event, the creator gets 100 and everyone
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# else gets 0.
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# some things which call this don't pass the create event: hack around
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# that.
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key = (EventTypes.Create, "", )
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create_event = auth_events.get(key)
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if (create_event is not None and
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151
tests/test_event_auth.py
Normal file
151
tests/test_event_auth.py
Normal file
@ -0,0 +1,151 @@
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# -*- coding: utf-8 -*-
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# Copyright 2018 New Vector Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
|
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from synapse import event_auth
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from synapse.api.errors import AuthError
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from synapse.events import FrozenEvent
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import unittest
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class EventAuthTestCase(unittest.TestCase):
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def test_random_users_cannot_send_state_before_first_pl(self):
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"""
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Check that, before the first PL lands, the creator is the only user
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that can send a state event.
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"""
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creator = "@creator:example.com"
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joiner = "@joiner:example.com"
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auth_events = {
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("m.room.create", ""): _create_event(creator),
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("m.room.member", creator): _join_event(creator),
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("m.room.member", joiner): _join_event(joiner),
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}
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# creator should be able to send state
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event_auth.check(
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_random_state_event(creator), auth_events,
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do_sig_check=False,
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)
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# joiner should not be able to send state
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self.assertRaises(
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AuthError,
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event_auth.check,
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_random_state_event(joiner),
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auth_events,
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do_sig_check=False,
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),
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def test_state_default_level(self):
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"""
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Check that users above the state_default level can send state and
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those below cannot
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"""
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creator = "@creator:example.com"
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pleb = "@joiner:example.com"
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king = "@joiner2:example.com"
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auth_events = {
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("m.room.create", ""): _create_event(creator),
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("m.room.member", creator): _join_event(creator),
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("m.room.power_levels", ""): _power_levels_event(creator, {
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"state_default": "30",
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"users": {
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pleb: "29",
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king: "30",
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},
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}),
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("m.room.member", pleb): _join_event(pleb),
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("m.room.member", king): _join_event(king),
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}
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# pleb should not be able to send state
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self.assertRaises(
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AuthError,
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event_auth.check,
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_random_state_event(pleb),
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auth_events,
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do_sig_check=False,
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),
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# king should be able to send state
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event_auth.check(
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_random_state_event(king), auth_events,
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do_sig_check=False,
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)
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# helpers for making events
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TEST_ROOM_ID = "!test:room"
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def _create_event(user_id):
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return FrozenEvent({
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"room_id": TEST_ROOM_ID,
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"event_id": _get_event_id(),
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"type": "m.room.create",
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"sender": user_id,
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"content": {
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"creator": user_id,
|
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},
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})
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|
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|
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def _join_event(user_id):
|
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return FrozenEvent({
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"room_id": TEST_ROOM_ID,
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"event_id": _get_event_id(),
|
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"type": "m.room.member",
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"sender": user_id,
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"state_key": user_id,
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"content": {
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"membership": "join",
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||||
},
|
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})
|
||||
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|
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def _power_levels_event(sender, content):
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return FrozenEvent({
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"room_id": TEST_ROOM_ID,
|
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"event_id": _get_event_id(),
|
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"type": "m.room.power_levels",
|
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"sender": sender,
|
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"state_key": "",
|
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"content": content,
|
||||
})
|
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|
||||
|
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def _random_state_event(sender):
|
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return FrozenEvent({
|
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"room_id": TEST_ROOM_ID,
|
||||
"event_id": _get_event_id(),
|
||||
"type": "test.state",
|
||||
"sender": sender,
|
||||
"state_key": "",
|
||||
"content": {
|
||||
"membership": "join",
|
||||
},
|
||||
})
|
||||
|
||||
|
||||
event_count = 0
|
||||
|
||||
|
||||
def _get_event_id():
|
||||
global event_count
|
||||
c = event_count
|
||||
event_count += 1
|
||||
return "!%i:example.com" % (c, )
|
||||
@ -606,6 +606,14 @@ class StateTestCase(unittest.TestCase):
|
||||
}
|
||||
)
|
||||
|
||||
power_levels = create_event(
|
||||
type=EventTypes.PowerLevels, state_key="",
|
||||
content={"users": {
|
||||
"@foo:bar": "100",
|
||||
"@user_id:example.com": "100",
|
||||
}}
|
||||
)
|
||||
|
||||
creation = create_event(
|
||||
type=EventTypes.Create, state_key="",
|
||||
content={"creator": "@foo:bar"}
|
||||
@ -613,12 +621,14 @@ class StateTestCase(unittest.TestCase):
|
||||
|
||||
old_state_1 = [
|
||||
creation,
|
||||
power_levels,
|
||||
member_event,
|
||||
create_event(type="test1", state_key="1", depth=1),
|
||||
]
|
||||
|
||||
old_state_2 = [
|
||||
creation,
|
||||
power_levels,
|
||||
member_event,
|
||||
create_event(type="test1", state_key="1", depth=2),
|
||||
]
|
||||
@ -633,7 +643,7 @@ class StateTestCase(unittest.TestCase):
|
||||
)
|
||||
|
||||
self.assertEqual(
|
||||
old_state_2[2].event_id, context.current_state_ids[("test1", "1")]
|
||||
old_state_2[3].event_id, context.current_state_ids[("test1", "1")]
|
||||
)
|
||||
|
||||
# Reverse the depth to make sure we are actually using the depths
|
||||
@ -641,12 +651,14 @@ class StateTestCase(unittest.TestCase):
|
||||
|
||||
old_state_1 = [
|
||||
creation,
|
||||
power_levels,
|
||||
member_event,
|
||||
create_event(type="test1", state_key="1", depth=2),
|
||||
]
|
||||
|
||||
old_state_2 = [
|
||||
creation,
|
||||
power_levels,
|
||||
member_event,
|
||||
create_event(type="test1", state_key="1", depth=1),
|
||||
]
|
||||
@ -659,7 +671,7 @@ class StateTestCase(unittest.TestCase):
|
||||
)
|
||||
|
||||
self.assertEqual(
|
||||
old_state_1[2].event_id, context.current_state_ids[("test1", "1")]
|
||||
old_state_1[3].event_id, context.current_state_ids[("test1", "1")]
|
||||
)
|
||||
|
||||
def _get_context(self, event, prev_event_id_1, old_state_1, prev_event_id_2,
|
||||
|
||||
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