679 lines
22 KiB
Python
679 lines
22 KiB
Python
# -*- coding: utf-8 -*-
|
|
# 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 canonicaljson import encode_canonical_json
|
|
from signedjson.key import decode_verify_key_bytes
|
|
from signedjson.sign import verify_signed_json, SignatureVerifyException
|
|
from unpaddedbase64 import decode_base64
|
|
|
|
from synapse.api.constants import EventTypes, Membership, JoinRules
|
|
from synapse.api.errors import AuthError, SynapseError, EventSizeError
|
|
from synapse.types import UserID, get_domain_from_id
|
|
|
|
logger = logging.getLogger(__name__)
|
|
|
|
|
|
def check(event, auth_events, do_sig_check=True, do_size_check=True):
|
|
""" 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.
|
|
"""
|
|
if do_size_check:
|
|
_check_size_limits(event)
|
|
|
|
if not hasattr(event, "room_id"):
|
|
raise AuthError(500, "Event has no room_id: %s" % event)
|
|
|
|
if do_sig_check:
|
|
sender_domain = get_domain_from_id(event.sender)
|
|
event_id_domain = get_domain_from_id(event.event_id)
|
|
|
|
is_invite_via_3pid = (
|
|
event.type == EventTypes.Member
|
|
and event.membership == Membership.INVITE
|
|
and "third_party_invite" in event.content
|
|
)
|
|
|
|
# Check the sender's domain has signed the event
|
|
if not event.signatures.get(sender_domain):
|
|
# We allow invites via 3pid to have a sender from a different
|
|
# HS, as the sender must match the sender of the original
|
|
# 3pid invite. This is checked further down with the
|
|
# other dedicated membership checks.
|
|
if not is_invite_via_3pid:
|
|
raise AuthError(403, "Event not signed by sender's server")
|
|
|
|
# Check the event_id's domain has signed the event
|
|
if not event.signatures.get(event_id_domain):
|
|
raise AuthError(403, "Event not signed by sending server")
|
|
|
|
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:
|
|
room_id_domain = get_domain_from_id(event.room_id)
|
|
if room_id_domain != sender_domain:
|
|
raise AuthError(
|
|
403,
|
|
"Creation event's room_id domain does not match sender's"
|
|
)
|
|
# 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 = get_domain_from_id(event.room_id)
|
|
originating_domain = get_domain_from_id(event.sender)
|
|
if creating_domain != originating_domain:
|
|
if not _can_federate(event, auth_events):
|
|
raise AuthError(
|
|
403,
|
|
"This room has been marked as unfederatable."
|
|
)
|
|
|
|
# FIXME: Temp hack
|
|
if event.type == EventTypes.Aliases:
|
|
if not event.is_state():
|
|
raise AuthError(
|
|
403,
|
|
"Alias event must be a state event",
|
|
)
|
|
if not event.state_key:
|
|
raise AuthError(
|
|
403,
|
|
"Alias event must have non-empty state_key"
|
|
)
|
|
sender_domain = get_domain_from_id(event.sender)
|
|
if event.state_key != sender_domain:
|
|
raise AuthError(
|
|
403,
|
|
"Alias event's state_key does not match sender's domain"
|
|
)
|
|
return True
|
|
|
|
if logger.isEnabledFor(logging.DEBUG):
|
|
logger.debug(
|
|
"Auth events: %s",
|
|
[a.event_id for a in auth_events.values()]
|
|
)
|
|
|
|
if event.type == EventTypes.Member:
|
|
allowed = _is_membership_change_allowed(
|
|
event, auth_events
|
|
)
|
|
if allowed:
|
|
logger.debug("Allowing! %s", event)
|
|
else:
|
|
logger.debug("Denying! %s", event)
|
|
return allowed
|
|
|
|
_check_event_sender_in_room(event, auth_events)
|
|
|
|
# Special case to allow m.room.third_party_invite events wherever
|
|
# a user is allowed to issue invites. Fixes
|
|
# https://github.com/vector-im/vector-web/issues/1208 hopefully
|
|
if event.type == EventTypes.ThirdPartyInvite:
|
|
user_level = get_user_power_level(event.user_id, auth_events)
|
|
invite_level = _get_named_level(auth_events, "invite", 0)
|
|
|
|
if user_level < invite_level:
|
|
raise AuthError(
|
|
403, (
|
|
"You cannot issue a third party invite for %s." %
|
|
(event.content.display_name,)
|
|
)
|
|
)
|
|
else:
|
|
return True
|
|
|
|
_can_send_event(event, auth_events)
|
|
|
|
if event.type == EventTypes.PowerLevels:
|
|
_check_power_levels(event, auth_events)
|
|
|
|
if event.type == EventTypes.Redaction:
|
|
check_redaction(event, auth_events)
|
|
|
|
logger.debug("Allowing! %s", event)
|
|
|
|
|
|
def _check_size_limits(event):
|
|
def too_big(field):
|
|
raise EventSizeError("%s too large" % (field,))
|
|
|
|
if len(event.user_id) > 255:
|
|
too_big("user_id")
|
|
if len(event.room_id) > 255:
|
|
too_big("room_id")
|
|
if event.is_state() and len(event.state_key) > 255:
|
|
too_big("state_key")
|
|
if len(event.type) > 255:
|
|
too_big("type")
|
|
if len(event.event_id) > 255:
|
|
too_big("event_id")
|
|
if len(encode_canonical_json(event.get_pdu_json())) > 65536:
|
|
too_big("event")
|
|
|
|
|
|
def _can_federate(event, auth_events):
|
|
creation_event = auth_events.get((EventTypes.Create, ""))
|
|
|
|
return creation_event.content.get("m.federate", True) is True
|
|
|
|
|
|
def _is_membership_change_allowed(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 = get_domain_from_id(event.room_id)
|
|
target_domain = get_domain_from_id(target_user_id)
|
|
if creating_domain != target_domain:
|
|
if not _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 = get_user_power_level(event.user_id, auth_events)
|
|
target_level = get_user_power_level(
|
|
target_user_id, auth_events
|
|
)
|
|
|
|
# FIXME (erikj): What should we do here as the default?
|
|
ban_level = _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.INVITE == membership and "third_party_invite" in event.content:
|
|
if not _verify_third_party_invite(event, auth_events):
|
|
raise AuthError(403, "You are not invited to this room.")
|
|
if target_banned:
|
|
raise AuthError(
|
|
403, "%s is banned from the room" % (target_user_id,)
|
|
)
|
|
return True
|
|
|
|
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 = _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:
|
|
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 = _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 _check_event_sender_in_room(event, auth_events):
|
|
key = (EventTypes.Member, event.user_id, )
|
|
member_event = auth_events.get(key)
|
|
|
|
return _check_joined_room(
|
|
member_event,
|
|
event.user_id,
|
|
event.room_id
|
|
)
|
|
|
|
|
|
def _check_joined_room(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 get_send_level(etype, state_key, 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(
|
|
etype
|
|
)
|
|
if send_level is None:
|
|
if state_key is not None:
|
|
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
|
|
|
|
return send_level
|
|
|
|
|
|
def _can_send_event(event, auth_events):
|
|
send_level = get_send_level(
|
|
event.type, event.get("state_key", None), auth_events
|
|
)
|
|
user_level = 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"
|
|
)
|
|
|
|
return True
|
|
|
|
|
|
def check_redaction(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 = get_user_power_level(event.user_id, auth_events)
|
|
|
|
redact_level = _get_named_level(auth_events, "redact", 50)
|
|
|
|
if user_level >= redact_level:
|
|
return False
|
|
|
|
redacter_domain = get_domain_from_id(event.event_id)
|
|
redactee_domain = get_domain_from_id(event.redacts)
|
|
if redacter_domain == redactee_domain:
|
|
return True
|
|
|
|
raise AuthError(
|
|
403,
|
|
"You don't have permission to redact events"
|
|
)
|
|
|
|
|
|
def _check_power_levels(event, auth_events):
|
|
user_list = event.content.get("users", {})
|
|
# Validate users
|
|
for k, v in user_list.items():
|
|
try:
|
|
UserID.from_string(k)
|
|
except Exception:
|
|
raise SynapseError(400, "Not a valid user_id: %s" % (k,))
|
|
|
|
try:
|
|
int(v)
|
|
except Exception:
|
|
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 = 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"
|
|
)
|
|
|
|
|
|
def _get_power_level_event(auth_events):
|
|
key = (EventTypes.PowerLevels, "", )
|
|
return auth_events.get(key)
|
|
|
|
|
|
def get_user_power_level(user_id, auth_events):
|
|
power_level_event = _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(auth_events, name, default):
|
|
power_level_event = _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
|
|
|
|
|
|
def _verify_third_party_invite(event, auth_events):
|
|
"""
|
|
Validates that the invite event is authorized by a previous third-party invite.
|
|
|
|
Checks that the public key, and keyserver, match those in the third party invite,
|
|
and that the invite 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 "third_party_invite" not in event.content:
|
|
return False
|
|
if "signed" not in event.content["third_party_invite"]:
|
|
return False
|
|
signed = event.content["third_party_invite"]["signed"]
|
|
for key in {"mxid", "token"}:
|
|
if key not in signed:
|
|
return False
|
|
|
|
token = signed["token"]
|
|
|
|
invite_event = auth_events.get(
|
|
(EventTypes.ThirdPartyInvite, token,)
|
|
)
|
|
if not invite_event:
|
|
return False
|
|
|
|
if invite_event.sender != event.sender:
|
|
return False
|
|
|
|
if event.user_id != invite_event.user_id:
|
|
return False
|
|
|
|
if signed["mxid"] != event.state_key:
|
|
return False
|
|
if signed["token"] != token:
|
|
return False
|
|
|
|
for public_key_object in get_public_keys(invite_event):
|
|
public_key = public_key_object["public_key"]
|
|
try:
|
|
for server, signature_block in signed["signatures"].items():
|
|
for key_name, encoded_signature in signature_block.items():
|
|
if not key_name.startswith("ed25519:"):
|
|
continue
|
|
verify_key = decode_verify_key_bytes(
|
|
key_name,
|
|
decode_base64(public_key)
|
|
)
|
|
verify_signed_json(signed, server, verify_key)
|
|
|
|
# We got the public key from the invite, so we know that the
|
|
# correct server signed the signed bundle.
|
|
# The caller is responsible for checking that the signing
|
|
# server has not revoked that public key.
|
|
return True
|
|
except (KeyError, SignatureVerifyException,):
|
|
continue
|
|
return False
|
|
|
|
|
|
def get_public_keys(invite_event):
|
|
public_keys = []
|
|
if "public_key" in invite_event.content:
|
|
o = {
|
|
"public_key": invite_event.content["public_key"],
|
|
}
|
|
if "key_validity_url" in invite_event.content:
|
|
o["key_validity_url"] = invite_event.content["key_validity_url"]
|
|
public_keys.append(o)
|
|
public_keys.extend(invite_event.content.get("public_keys", []))
|
|
return public_keys
|
|
|
|
|
|
def auth_types_for_event(event):
|
|
"""Given an event, return a list of (EventType, StateKey) that may be
|
|
needed to auth the event. The returned list may be a superset of what
|
|
would actually be required depending on the full state of the room.
|
|
|
|
Used to limit the number of events to fetch from the database to
|
|
actually auth the event.
|
|
"""
|
|
if event.type == EventTypes.Create:
|
|
return []
|
|
|
|
auth_types = []
|
|
|
|
auth_types.append((EventTypes.PowerLevels, "", ))
|
|
auth_types.append((EventTypes.Member, event.user_id, ))
|
|
auth_types.append((EventTypes.Create, "", ))
|
|
|
|
if event.type == EventTypes.Member:
|
|
membership = event.content["membership"]
|
|
if membership in [Membership.JOIN, Membership.INVITE]:
|
|
auth_types.append((EventTypes.JoinRules, "", ))
|
|
|
|
auth_types.append((EventTypes.Member, event.state_key, ))
|
|
|
|
if membership == Membership.INVITE:
|
|
if "third_party_invite" in event.content:
|
|
key = (
|
|
EventTypes.ThirdPartyInvite,
|
|
event.content["third_party_invite"]["signed"]["token"]
|
|
)
|
|
auth_types.append(key)
|
|
|
|
return auth_types
|