Implement cancellation support/protection for module callbacks (#12568)

There's no guarantee that module callbacks will handle cancellation
appropriately. Protect module callbacks with read semantics from
cancellation and avoid swallowing `CancelledError`s that arise.

Other module callbacks, such as the `on_*` callbacks, are presumed to
live on code paths that involve writes and aren't cancellation-friendly.
These module callbacks have been left alone.

Signed-off-by: Sean Quah <seanq@element.io>
This commit is contained in:
Sean Quah 2022-05-09 12:31:14 +01:00 committed by GitHub
parent 8de0facaae
commit a00462dd99
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6 changed files with 86 additions and 27 deletions

1
changelog.d/12568.misc Normal file
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@ -0,0 +1 @@
Protect module callbacks with read semantics against cancellation.

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@ -28,8 +28,10 @@ from typing import (
from typing_extensions import ParamSpec
from twisted.internet.defer import CancelledError
from synapse.api.presence import UserPresenceState
from synapse.util.async_helpers import maybe_awaitable
from synapse.util.async_helpers import delay_cancellation, maybe_awaitable
if TYPE_CHECKING:
from synapse.server import HomeServer
@ -158,7 +160,9 @@ class PresenceRouter:
try:
# Note: result is an object here, because we don't trust modules to
# return the types they're supposed to.
result: object = await callback(state_updates)
result: object = await delay_cancellation(callback(state_updates))
except CancelledError:
raise
except Exception as e:
logger.warning("Failed to run module API callback %s: %s", callback, e)
continue
@ -210,7 +214,9 @@ class PresenceRouter:
# run all the callbacks for get_interested_users and combine the results
for callback in self._get_interested_users_callbacks:
try:
result = await callback(user_id)
result = await delay_cancellation(callback(user_id))
except CancelledError:
raise
except Exception as e:
logger.warning("Failed to run module API callback %s: %s", callback, e)
continue

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@ -31,7 +31,7 @@ from synapse.rest.media.v1._base import FileInfo
from synapse.rest.media.v1.media_storage import ReadableFileWrapper
from synapse.spam_checker_api import RegistrationBehaviour
from synapse.types import RoomAlias, UserProfile
from synapse.util.async_helpers import maybe_awaitable
from synapse.util.async_helpers import delay_cancellation, maybe_awaitable
if TYPE_CHECKING:
import synapse.events
@ -255,7 +255,7 @@ class SpamChecker:
will be used as the error message returned to the user.
"""
for callback in self._check_event_for_spam_callbacks:
res: Union[bool, str] = await callback(event)
res: Union[bool, str] = await delay_cancellation(callback(event))
if res:
return res
@ -276,7 +276,10 @@ class SpamChecker:
Whether the user may join the room
"""
for callback in self._user_may_join_room_callbacks:
if await callback(user_id, room_id, is_invited) is False:
may_join_room = await delay_cancellation(
callback(user_id, room_id, is_invited)
)
if may_join_room is False:
return False
return True
@ -297,7 +300,10 @@ class SpamChecker:
True if the user may send an invite, otherwise False
"""
for callback in self._user_may_invite_callbacks:
if await callback(inviter_userid, invitee_userid, room_id) is False:
may_invite = await delay_cancellation(
callback(inviter_userid, invitee_userid, room_id)
)
if may_invite is False:
return False
return True
@ -322,7 +328,10 @@ class SpamChecker:
True if the user may send the invite, otherwise False
"""
for callback in self._user_may_send_3pid_invite_callbacks:
if await callback(inviter_userid, medium, address, room_id) is False:
may_send_3pid_invite = await delay_cancellation(
callback(inviter_userid, medium, address, room_id)
)
if may_send_3pid_invite is False:
return False
return True
@ -339,7 +348,8 @@ class SpamChecker:
True if the user may create a room, otherwise False
"""
for callback in self._user_may_create_room_callbacks:
if await callback(userid) is False:
may_create_room = await delay_cancellation(callback(userid))
if may_create_room is False:
return False
return True
@ -359,7 +369,10 @@ class SpamChecker:
True if the user may create a room alias, otherwise False
"""
for callback in self._user_may_create_room_alias_callbacks:
if await callback(userid, room_alias) is False:
may_create_room_alias = await delay_cancellation(
callback(userid, room_alias)
)
if may_create_room_alias is False:
return False
return True
@ -377,7 +390,8 @@ class SpamChecker:
True if the user may publish the room, otherwise False
"""
for callback in self._user_may_publish_room_callbacks:
if await callback(userid, room_id) is False:
may_publish_room = await delay_cancellation(callback(userid, room_id))
if may_publish_room is False:
return False
return True
@ -400,7 +414,7 @@ class SpamChecker:
for callback in self._check_username_for_spam_callbacks:
# Make a copy of the user profile object to ensure the spam checker cannot
# modify it.
if await callback(user_profile.copy()):
if await delay_cancellation(callback(user_profile.copy())):
return True
return False
@ -428,7 +442,7 @@ class SpamChecker:
"""
for callback in self._check_registration_for_spam_callbacks:
behaviour = await (
behaviour = await delay_cancellation(
callback(email_threepid, username, request_info, auth_provider_id)
)
assert isinstance(behaviour, RegistrationBehaviour)
@ -472,7 +486,7 @@ class SpamChecker:
"""
for callback in self._check_media_file_for_spam_callbacks:
spam = await callback(file_wrapper, file_info)
spam = await delay_cancellation(callback(file_wrapper, file_info))
if spam:
return True

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@ -14,12 +14,14 @@
import logging
from typing import TYPE_CHECKING, Any, Awaitable, Callable, List, Optional, Tuple
from twisted.internet.defer import CancelledError
from synapse.api.errors import ModuleFailedException, SynapseError
from synapse.events import EventBase
from synapse.events.snapshot import EventContext
from synapse.storage.roommember import ProfileInfo
from synapse.types import Requester, StateMap
from synapse.util.async_helpers import maybe_awaitable
from synapse.util.async_helpers import delay_cancellation, maybe_awaitable
if TYPE_CHECKING:
from synapse.server import HomeServer
@ -263,7 +265,11 @@ class ThirdPartyEventRules:
for callback in self._check_event_allowed_callbacks:
try:
res, replacement_data = await callback(event, state_events)
res, replacement_data = await delay_cancellation(
callback(event, state_events)
)
except CancelledError:
raise
except SynapseError as e:
# FIXME: Being able to throw SynapseErrors is relied upon by
# some modules. PR #10386 accidentally broke this ability.
@ -333,8 +339,13 @@ class ThirdPartyEventRules:
for callback in self._check_threepid_can_be_invited_callbacks:
try:
if await callback(medium, address, state_events) is False:
threepid_can_be_invited = await delay_cancellation(
callback(medium, address, state_events)
)
if threepid_can_be_invited is False:
return False
except CancelledError:
raise
except Exception as e:
logger.warning("Failed to run module API callback %s: %s", callback, e)
@ -361,8 +372,13 @@ class ThirdPartyEventRules:
for callback in self._check_visibility_can_be_modified_callbacks:
try:
if await callback(room_id, state_events, new_visibility) is False:
visibility_can_be_modified = await delay_cancellation(
callback(room_id, state_events, new_visibility)
)
if visibility_can_be_modified is False:
return False
except CancelledError:
raise
except Exception as e:
logger.warning("Failed to run module API callback %s: %s", callback, e)
@ -400,8 +416,11 @@ class ThirdPartyEventRules:
"""
for callback in self._check_can_shutdown_room_callbacks:
try:
if await callback(user_id, room_id) is False:
can_shutdown_room = await delay_cancellation(callback(user_id, room_id))
if can_shutdown_room is False:
return False
except CancelledError:
raise
except Exception as e:
logger.exception(
"Failed to run module API callback %s: %s", callback, e
@ -422,8 +441,13 @@ class ThirdPartyEventRules:
"""
for callback in self._check_can_deactivate_user_callbacks:
try:
if await callback(user_id, by_admin) is False:
can_deactivate_user = await delay_cancellation(
callback(user_id, by_admin)
)
if can_deactivate_user is False:
return False
except CancelledError:
raise
except Exception as e:
logger.exception(
"Failed to run module API callback %s: %s", callback, e

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@ -23,6 +23,7 @@ from synapse.api.errors import AuthError, StoreError, SynapseError
from synapse.metrics.background_process_metrics import wrap_as_background_process
from synapse.types import UserID
from synapse.util import stringutils
from synapse.util.async_helpers import delay_cancellation
if TYPE_CHECKING:
from synapse.server import HomeServer
@ -150,7 +151,7 @@ class AccountValidityHandler:
Whether the user has expired.
"""
for callback in self._is_user_expired_callbacks:
expired = await callback(user_id)
expired = await delay_cancellation(callback(user_id))
if expired is not None:
return expired

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@ -41,6 +41,7 @@ import pymacaroons
import unpaddedbase64
from pymacaroons.exceptions import MacaroonVerificationFailedException
from twisted.internet.defer import CancelledError
from twisted.web.server import Request
from synapse.api.constants import LoginType
@ -67,7 +68,7 @@ from synapse.metrics.background_process_metrics import run_as_background_process
from synapse.storage.roommember import ProfileInfo
from synapse.types import JsonDict, Requester, UserID
from synapse.util import stringutils as stringutils
from synapse.util.async_helpers import maybe_awaitable
from synapse.util.async_helpers import delay_cancellation, maybe_awaitable
from synapse.util.macaroons import get_value_from_macaroon, satisfy_expiry
from synapse.util.msisdn import phone_number_to_msisdn
from synapse.util.stringutils import base62_encode
@ -2202,7 +2203,11 @@ class PasswordAuthProvider:
# other than None (i.e. until a callback returns a success)
for callback in self.auth_checker_callbacks[login_type]:
try:
result = await callback(username, login_type, login_dict)
result = await delay_cancellation(
callback(username, login_type, login_dict)
)
except CancelledError:
raise
except Exception as e:
logger.warning("Failed to run module API callback %s: %s", callback, e)
continue
@ -2263,7 +2268,9 @@ class PasswordAuthProvider:
for callback in self.check_3pid_auth_callbacks:
try:
result = await callback(medium, address, password)
result = await delay_cancellation(callback(medium, address, password))
except CancelledError:
raise
except Exception as e:
logger.warning("Failed to run module API callback %s: %s", callback, e)
continue
@ -2345,7 +2352,7 @@ class PasswordAuthProvider:
"""
for callback in self.get_username_for_registration_callbacks:
try:
res = await callback(uia_results, params)
res = await delay_cancellation(callback(uia_results, params))
if isinstance(res, str):
return res
@ -2359,6 +2366,8 @@ class PasswordAuthProvider:
callback,
res,
)
except CancelledError:
raise
except Exception as e:
logger.error(
"Module raised an exception in get_username_for_registration: %s",
@ -2388,7 +2397,7 @@ class PasswordAuthProvider:
"""
for callback in self.get_displayname_for_registration_callbacks:
try:
res = await callback(uia_results, params)
res = await delay_cancellation(callback(uia_results, params))
if isinstance(res, str):
return res
@ -2402,6 +2411,8 @@ class PasswordAuthProvider:
callback,
res,
)
except CancelledError:
raise
except Exception as e:
logger.error(
"Module raised an exception in get_displayname_for_registration: %s",
@ -2429,7 +2440,7 @@ class PasswordAuthProvider:
"""
for callback in self.is_3pid_allowed_callbacks:
try:
res = await callback(medium, address, registration)
res = await delay_cancellation(callback(medium, address, registration))
if res is False:
return res
@ -2443,6 +2454,8 @@ class PasswordAuthProvider:
callback,
res,
)
except CancelledError:
raise
except Exception as e:
logger.error("Module raised an exception in is_3pid_allowed: %s", e)
raise SynapseError(code=500, msg="Internal Server Error")