Implement soft fail

This commit is contained in:
Erik Johnston 2019-02-12 10:31:21 +00:00
parent 16c8b4ecbd
commit a9de04be72
4 changed files with 95 additions and 1 deletions

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@ -77,6 +77,20 @@ class _EventInternalMetadata(object):
""" """
return getattr(self, "recheck_redaction", False) return getattr(self, "recheck_redaction", False)
def is_soft_failed(self):
"""Whether the event has been soft failed.
Soft failed events should be handled as usual, except:
1. They should not go down sync or event streams, or generally
sent to clients.
2. They should not be added to the forward extremities (and
therefore not to current state).
Returns:
bool
"""
return getattr(self, "soft_failed", False)
def _event_dict_property(key): def _event_dict_property(key):
# We want to be able to use hasattr with the event dict properties. # We want to be able to use hasattr with the event dict properties.

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@ -45,6 +45,7 @@ from synapse.api.errors import (
SynapseError, SynapseError,
) )
from synapse.crypto.event_signing import compute_event_signature from synapse.crypto.event_signing import compute_event_signature
from synapse.event_auth import auth_types_for_event
from synapse.events.validator import EventValidator from synapse.events.validator import EventValidator
from synapse.replication.http.federation import ( from synapse.replication.http.federation import (
ReplicationCleanRoomRestServlet, ReplicationCleanRoomRestServlet,
@ -1628,6 +1629,7 @@ class FederationHandler(BaseHandler):
origin, event, origin, event,
state=state, state=state,
auth_events=auth_events, auth_events=auth_events,
backfilled=backfilled,
) )
# reraise does not allow inlineCallbacks to preserve the stacktrace, so we # reraise does not allow inlineCallbacks to preserve the stacktrace, so we
@ -1672,6 +1674,7 @@ class FederationHandler(BaseHandler):
event, event,
state=ev_info.get("state"), state=ev_info.get("state"),
auth_events=ev_info.get("auth_events"), auth_events=ev_info.get("auth_events"),
backfilled=backfilled,
) )
defer.returnValue(res) defer.returnValue(res)
@ -1794,7 +1797,7 @@ class FederationHandler(BaseHandler):
) )
@defer.inlineCallbacks @defer.inlineCallbacks
def _prep_event(self, origin, event, state=None, auth_events=None): def _prep_event(self, origin, event, state, auth_events, backfilled):
""" """
Args: Args:
@ -1802,6 +1805,7 @@ class FederationHandler(BaseHandler):
event: event:
state: state:
auth_events: auth_events:
backfilled (bool)
Returns: Returns:
Deferred, which resolves to synapse.events.snapshot.EventContext Deferred, which resolves to synapse.events.snapshot.EventContext
@ -1843,6 +1847,77 @@ class FederationHandler(BaseHandler):
context.rejected = RejectedReason.AUTH_ERROR context.rejected = RejectedReason.AUTH_ERROR
# For new (non-backfilled and non-outlier) events we check if the event
# passes auth based on the current state. If it doesn't then we
# "soft-fail" the event.
do_soft_fail_check = not backfilled and not event.internal_metadata.is_outlier()
if do_soft_fail_check:
extrem_ids = yield self.store.get_latest_event_ids_in_room(
event.room_id,
)
extrem_ids = set(extrem_ids)
prev_event_ids = set(event.prev_event_ids())
if extrem_ids == prev_event_ids:
# If they're the same then the current state is the same as the
# state at the event, so no point rechecking auth for soft fail.
do_soft_fail_check = False
if do_soft_fail_check:
room_version = yield self.store.get_room_version(event.room_id)
# Calculate the "current state".
if state is not None:
# If we're explicitly given the state then we won't have all the
# prev events, and so we have a gap in the graph. In this case
# we want to be a little careful as we might have been down for
# a while and have an incorrect view of the current state,
# however we still want to do checks as gaps are easy to
# maliciously manufacture.
#
# So we use a "current state" that is actually a state
# resolution across the current forward extremities and the
# given state at the event. This should correctly handle cases
# like bans, especially with state res v2.
state_sets = yield self.store.get_state_groups(
event.room_id, extrem_ids,
)
state_sets = list(state_sets.values())
state_sets.append(state)
current_state_ids = yield self.state_handler.resolve_events(
room_version, state_sets, event,
)
current_state_ids = {
k: e.event_id for k, e in iteritems(current_state_ids)
}
else:
current_state_ids = yield self.state_handler.get_current_state_ids(
event.room_id, latest_event_ids=extrem_ids,
)
# Now check if event pass auth against said current state
auth_types = auth_types_for_event(event)
current_state_ids = [
e for k, e in iteritems(current_state_ids)
if k in auth_types
]
current_auth_events = yield self.store.get_events(current_state_ids)
current_auth_events = {
(e.type, e.state_key): e for e in current_auth_events.values()
}
try:
self.auth.check(room_version, event, auth_events=current_auth_events)
except AuthError as e:
logger.warn(
"Failed current state auth resolution for %r because %s",
event, e,
)
event.internal_metadata.soft_failed = True
if event.type == EventTypes.GuestAccess and not context.rejected: if event.type == EventTypes.GuestAccess and not context.rejected:
yield self.maybe_kick_guest_users(event) yield self.maybe_kick_guest_users(event)

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@ -537,6 +537,7 @@ class EventsStore(StateGroupWorkerStore, EventFederationStore, EventsWorkerStore
new_events = [ new_events = [
event for event, ctx in event_contexts event for event, ctx in event_contexts
if not event.internal_metadata.is_outlier() and not ctx.rejected if not event.internal_metadata.is_outlier() and not ctx.rejected
and not event.internal_metadata.is_soft_failed()
] ]
# start with the existing forward extremities # start with the existing forward extremities

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@ -67,6 +67,10 @@ def filter_events_for_client(store, user_id, events, is_peeking=False,
Returns: Returns:
Deferred[list[synapse.events.EventBase]] Deferred[list[synapse.events.EventBase]]
""" """
# Filter out events that have been soft failed so that we don't relay them
# to clients.
events = list(e for e in events if not e.internal_metadata.is_soft_failed())
types = ( types = (
(EventTypes.RoomHistoryVisibility, ""), (EventTypes.RoomHistoryVisibility, ""),
(EventTypes.Member, user_id), (EventTypes.Member, user_id),