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Split event auth code into seperate module

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This commit is contained in:
Erik Johnston 2017-01-13 15:07:32 +00:00
parent 7e6c2937c3
commit 8b2fa38256
2 changed files with 650 additions and 645 deletions
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654
synapse/api/auth.py
View file

@ -16,16 +16,13 @@
import logging import logging
import pymacaroons import pymacaroons
from canonicaljson import encode_canonical_json
from signedjson.key import decode_verify_key_bytes
from signedjson.sign import verify_signed_json, SignatureVerifyException
from twisted.internet import defer from twisted.internet import defer
from unpaddedbase64 import decode_base64
import synapse.types import synapse.types
from synapse import event_auth
from synapse.api.constants import EventTypes, Membership, JoinRules from synapse.api.constants import EventTypes, Membership, JoinRules
from synapse.api.errors import AuthError, Codes, SynapseError, EventSizeError from synapse.api.errors import AuthError, Codes
from synapse.types import UserID, get_domain_from_id from synapse.types import UserID
from synapse.util.logcontext import preserve_context_over_fn from synapse.util.logcontext import preserve_context_over_fn
from synapse.util.metrics import Measure from synapse.util.metrics import Measure
@ -42,622 +39,6 @@ AuthEventTypes = (
GUEST_DEVICE_ID = "guest_device" GUEST_DEVICE_ID = "guest_device"
class Auther(object):
@staticmethod
def check(event, auth_events, do_sig_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.
"""
Auther.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 Auther.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
logger.debug(
"Auth events: %s",
[a.event_id for a in auth_events.values()]
)
if event.type == EventTypes.Member:
allowed = Auther.is_membership_change_allowed(
event, auth_events
)
if allowed:
logger.debug("Allowing! %s", event)
else:
logger.debug("Denying! %s", event)
return allowed
Auther.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 = Auther._get_user_power_level(event.user_id, auth_events)
invite_level = Auther._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
Auther._can_send_event(event, auth_events)
if event.type == EventTypes.PowerLevels:
Auther._check_power_levels(event, auth_events)
if event.type == EventTypes.Redaction:
Auther.check_redaction(event, auth_events)
logger.debug("Allowing! %s", event)
@staticmethod
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")
@staticmethod
def can_federate(event, auth_events):
creation_event = auth_events.get((EventTypes.Create, ""))
return creation_event.content.get("m.federate", True) is True
@staticmethod
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 Auther.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 = Auther._get_user_power_level(event.user_id, auth_events)
target_level = Auther._get_user_power_level(
target_user_id, auth_events
)
# FIXME (erikj): What should we do here as the default?
ban_level = Auther._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 Auther._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 = Auther._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 = Auther._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
@staticmethod
def check_event_sender_in_room(event, auth_events):
key = (EventTypes.Member, event.user_id, )
member_event = auth_events.get(key)
return Auther._check_joined_room(
member_event,
event.user_id,
event.room_id
)
@staticmethod
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)
))
@staticmethod
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
@staticmethod
def _can_send_event(event, auth_events):
send_level = Auther._get_send_level(
event.type, event.get("state_key", None), auth_events
)
user_level = Auther._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
@staticmethod
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 = Auther._get_user_power_level(event.user_id, auth_events)
redact_level = Auther._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"
)
@staticmethod
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:
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 = Auther._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"
)
@staticmethod
def _get_power_level_event(auth_events):
key = (EventTypes.PowerLevels, "", )
return auth_events.get(key)
@staticmethod
def _get_user_power_level(user_id, auth_events):
power_level_event = Auther._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
@staticmethod
def _get_named_level(auth_events, name, default):
power_level_event = Auther._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
@staticmethod
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 Auther.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
@staticmethod
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
class Auth(object): class Auth(object):
""" """
FIXME: This class contains a mix of functions for authenticating users FIXME: This class contains a mix of functions for authenticating users
@ -693,24 +74,7 @@ class Auth(object):
True if the auth checks pass. True if the auth checks pass.
""" """
with Measure(self.clock, "auth.check"): with Measure(self.clock, "auth.check"):
Auther.check(event, auth_events, do_sig_check=do_sig_check) event_auth.check(event, auth_events, do_sig_check=do_sig_check)
def check_size_limits(self, 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")
@defer.inlineCallbacks @defer.inlineCallbacks
def check_joined_room(self, room_id, user_id, current_state=None): def check_joined_room(self, room_id, user_id, current_state=None):
@ -804,7 +168,7 @@ class Auth(object):
return creation_event.content.get("m.federate", True) is True return creation_event.content.get("m.federate", True) is True
def get_public_keys(self, invite_event): def get_public_keys(self, invite_event):
return Auther.get_public_keys(invite_event) return event_auth.get_public_keys(invite_event)
@defer.inlineCallbacks @defer.inlineCallbacks
def get_user_by_req(self, request, allow_guest=False, rights="access"): def get_user_by_req(self, request, allow_guest=False, rights="access"):
@ -1198,7 +562,7 @@ class Auth(object):
defer.returnValue(auth_ids) defer.returnValue(auth_ids)
def _get_send_level(self, etype, state_key, auth_events): def _get_send_level(self, etype, state_key, auth_events):
return Auther._get_send_level(etype, state_key, auth_events) return event_auth._get_send_level(etype, state_key, auth_events)
def check_redaction(self, event, auth_events): def check_redaction(self, event, auth_events):
"""Check whether the event sender is allowed to redact the target event. """Check whether the event sender is allowed to redact the target event.
@ -1213,7 +577,7 @@ class Auth(object):
AuthError if the event sender is definitely not allowed to redact AuthError if the event sender is definitely not allowed to redact
the target event. the target event.
""" """
return Auther.check_redaction(event, auth_events) return event_auth.check_redaction(event, auth_events)
@defer.inlineCallbacks @defer.inlineCallbacks
def check_can_change_room_list(self, room_id, user): def check_can_change_room_list(self, room_id, user):
@ -1243,10 +607,10 @@ class Auth(object):
if power_level_event: if power_level_event:
auth_events[(EventTypes.PowerLevels, "")] = power_level_event auth_events[(EventTypes.PowerLevels, "")] = power_level_event
send_level = Auther._get_send_level( send_level = event_auth.get_send_level(
EventTypes.Aliases, "", auth_events EventTypes.Aliases, "", auth_events
) )
user_level = Auther._get_user_power_level(user_id, auth_events) user_level = event_auth.get_user_power_level(user_id, auth_events)
if user_level < send_level: if user_level < send_level:
raise AuthError( raise AuthError(

641
synapse/event_auth.py Normal file
View file

@ -0,0 +1,641 @@
# -*- 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):
""" 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.
"""
_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
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:
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 = 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