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Strip "join_authorised_via_users_server" from join events which do not need it. (#10933)

This fixes a "Event not signed by authorising server" error when
transition room member from join -> join, e.g. when updating a
display name or avatar URL for restricted rooms.
This commit is contained in:
Patrick Cloke 2021-09-30 11:13:59 -04:00 committed by GitHub
parent 7d84d2523a
commit d1bf5f7c9d
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GPG key ID: 4AEE18F83AFDEB23
11 changed files with 46 additions and 25 deletions

1
changelog.d/10933.bugfix Normal file
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@ -0,0 +1 @@
Fix a bug introduced in Synapse v1.40.0 where changing a user's display name or avatar in a restricted room would cause an authentication error.

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@ -217,6 +217,9 @@ class EventContentFields:
# For "marker" events
MSC2716_MARKER_INSERTION = "org.matrix.msc2716.marker.insertion"
# The authorising user for joining a restricted room.
AUTHORISING_USER = "join_authorised_via_users_server"
class RoomTypes:
"""Understood values of the room_type field of m.room.create events."""

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@ -102,11 +102,11 @@ def validate_event_for_room_version(
room_version_obj.msc3083_join_rules
and event.type == EventTypes.Member
and event.membership == Membership.JOIN
and "join_authorised_via_users_server" in event.content
and EventContentFields.AUTHORISING_USER in event.content
)
if is_invite_via_allow_rule:
authoriser_domain = get_domain_from_id(
event.content["join_authorised_via_users_server"]
event.content[EventContentFields.AUTHORISING_USER]
)
if not event.signatures.get(authoriser_domain):
raise AuthError(403, "Event not signed by authorising server")
@ -413,7 +413,9 @@ def _is_membership_change_allowed(
# Note that if the caller is in the room or invited, then they do
# not need to meet the allow rules.
if not caller_in_room and not caller_invited:
authorising_user = event.content.get("join_authorised_via_users_server")
authorising_user = event.content.get(
EventContentFields.AUTHORISING_USER
)
if authorising_user is None:
raise AuthError(403, "Join event is missing authorising user.")
@ -868,10 +870,10 @@ def auth_types_for_event(
auth_types.add(key)
if room_version.msc3083_join_rules and membership == Membership.JOIN:
if "join_authorised_via_users_server" in event.content:
if EventContentFields.AUTHORISING_USER in event.content:
key = (
EventTypes.Member,
event.content["join_authorised_via_users_server"],
event.content[EventContentFields.AUTHORISING_USER],
)
auth_types.add(key)

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@ -105,7 +105,7 @@ def prune_event_dict(room_version: RoomVersion, event_dict: dict) -> dict:
if event_type == EventTypes.Member:
add_fields("membership")
if room_version.msc3375_redaction_rules:
add_fields("join_authorised_via_users_server")
add_fields(EventContentFields.AUTHORISING_USER)
elif event_type == EventTypes.Create:
# MSC2176 rules state that create events cannot be redacted.
if room_version.msc2176_redaction_rules:

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@ -15,7 +15,7 @@
import logging
from collections import namedtuple
from synapse.api.constants import MAX_DEPTH, EventTypes, Membership
from synapse.api.constants import MAX_DEPTH, EventContentFields, EventTypes, Membership
from synapse.api.errors import Codes, SynapseError
from synapse.api.room_versions import EventFormatVersions, RoomVersion
from synapse.crypto.event_signing import check_event_content_hash
@ -184,10 +184,10 @@ async def _check_sigs_on_pdu(
room_version.msc3083_join_rules
and pdu.type == EventTypes.Member
and pdu.membership == Membership.JOIN
and "join_authorised_via_users_server" in pdu.content
and EventContentFields.AUTHORISING_USER in pdu.content
):
authorising_server = get_domain_from_id(
pdu.content["join_authorised_via_users_server"]
pdu.content[EventContentFields.AUTHORISING_USER]
)
try:
await keyring.verify_event_for_server(

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@ -37,7 +37,7 @@ from typing import (
import attr
from prometheus_client import Counter
from synapse.api.constants import EventTypes, Membership
from synapse.api.constants import EventContentFields, EventTypes, Membership
from synapse.api.errors import (
CodeMessageException,
Codes,
@ -875,9 +875,9 @@ class FederationClient(FederationBase):
# If the join is being authorised via allow rules, we need to send
# the /send_join back to the same server that was originally used
# with /make_join.
if "join_authorised_via_users_server" in pdu.content:
if EventContentFields.AUTHORISING_USER in pdu.content:
destinations = [
get_domain_from_id(pdu.content["join_authorised_via_users_server"])
get_domain_from_id(pdu.content[EventContentFields.AUTHORISING_USER])
]
return await self._try_destination_list(

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@ -34,7 +34,7 @@ from twisted.internet import defer
from twisted.internet.abstract import isIPAddress
from twisted.python import failure
from synapse.api.constants import EduTypes, EventTypes, Membership
from synapse.api.constants import EduTypes, EventContentFields, EventTypes, Membership
from synapse.api.errors import (
AuthError,
Codes,
@ -765,11 +765,11 @@ class FederationServer(FederationBase):
if (
room_version.msc3083_join_rules
and event.membership == Membership.JOIN
and "join_authorised_via_users_server" in event.content
and EventContentFields.AUTHORISING_USER in event.content
):
# We can only authorise our own users.
authorising_server = get_domain_from_id(
event.content["join_authorised_via_users_server"]
event.content[EventContentFields.AUTHORISING_USER]
)
if authorising_server != self.server_name:
raise SynapseError(

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@ -27,7 +27,12 @@ from unpaddedbase64 import decode_base64
from twisted.internet import defer
from synapse import event_auth
from synapse.api.constants import EventTypes, Membership, RejectedReason
from synapse.api.constants import (
EventContentFields,
EventTypes,
Membership,
RejectedReason,
)
from synapse.api.errors import (
AuthError,
CodeMessageException,
@ -716,7 +721,7 @@ class FederationHandler(BaseHandler):
if include_auth_user_id:
event_content[
"join_authorised_via_users_server"
EventContentFields.AUTHORISING_USER
] = await self._event_auth_handler.get_user_which_could_invite(
room_id,
state_ids,

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@ -573,6 +573,14 @@ class RoomMemberHandler(metaclass=abc.ABCMeta):
errcode=Codes.BAD_JSON,
)
# The event content should *not* include the authorising user as
# it won't be properly signed. Strip it out since it might come
# back from a client updating a display name / avatar.
#
# This only applies to restricted rooms, but there should be no reason
# for a client to include it. Unconditionally remove it.
content.pop(EventContentFields.AUTHORISING_USER, None)
effective_membership_state = action
if action in ["kick", "unban"]:
effective_membership_state = "leave"
@ -939,7 +947,7 @@ class RoomMemberHandler(metaclass=abc.ABCMeta):
# be included in the event content in order to efficiently validate
# the event.
content[
"join_authorised_via_users_server"
EventContentFields.AUTHORISING_USER
] = await self.event_auth_handler.get_user_which_could_invite(
room_id,
current_state_ids,

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@ -12,6 +12,7 @@
# See the License for the specific language governing permissions and
# limitations under the License.
from synapse.api.constants import EventContentFields
from synapse.api.room_versions import RoomVersions
from synapse.events import make_event_from_dict
from synapse.events.utils import (
@ -352,7 +353,7 @@ class PruneEventTestCase(unittest.TestCase):
"event_id": "$test:domain",
"content": {
"membership": "join",
"join_authorised_via_users_server": "@user:domain",
EventContentFields.AUTHORISING_USER: "@user:domain",
"other_key": "stripped",
},
},
@ -372,7 +373,7 @@ class PruneEventTestCase(unittest.TestCase):
"type": "m.room.member",
"content": {
"membership": "join",
"join_authorised_via_users_server": "@user:domain",
EventContentFields.AUTHORISING_USER: "@user:domain",
"other_key": "stripped",
},
},
@ -380,7 +381,7 @@ class PruneEventTestCase(unittest.TestCase):
"type": "m.room.member",
"content": {
"membership": "join",
"join_authorised_via_users_server": "@user:domain",
EventContentFields.AUTHORISING_USER: "@user:domain",
},
"signatures": {},
"unsigned": {},

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@ -16,6 +16,7 @@ import unittest
from typing import Optional
from synapse import event_auth
from synapse.api.constants import EventContentFields
from synapse.api.errors import AuthError
from synapse.api.room_versions import RoomVersions
from synapse.events import EventBase, make_event_from_dict
@ -353,7 +354,7 @@ class EventAuthTestCase(unittest.TestCase):
authorised_join_event = _join_event(
pleb,
additional_content={
"join_authorised_via_users_server": "@creator:example.com"
EventContentFields.AUTHORISING_USER: "@creator:example.com"
},
)
event_auth.check_auth_rules_for_event(
@ -376,7 +377,7 @@ class EventAuthTestCase(unittest.TestCase):
_join_event(
pleb,
additional_content={
"join_authorised_via_users_server": "@inviter:foo.test"
EventContentFields.AUTHORISING_USER: "@inviter:foo.test"
},
),
pl_auth_events,
@ -401,7 +402,7 @@ class EventAuthTestCase(unittest.TestCase):
_join_event(
pleb,
additional_content={
"join_authorised_via_users_server": "@other:example.com"
EventContentFields.AUTHORISING_USER: "@other:example.com"
},
),
auth_events,
@ -417,7 +418,7 @@ class EventAuthTestCase(unittest.TestCase):
"join",
sender=creator,
additional_content={
"join_authorised_via_users_server": "@inviter:foo.test"
EventContentFields.AUTHORISING_USER: "@inviter:foo.test"
},
),
auth_events,