mirror of
https://git.anonymousland.org/anonymousland/synapse-product.git
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163 lines
6.3 KiB
Python
163 lines
6.3 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2017 New Vector Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import logging
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from twisted.internet import defer
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from synapse.api.errors import StoreError, SynapseError, RoomKeysVersionError
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from synapse.util.async import Linearizer
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logger = logging.getLogger(__name__)
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class E2eRoomKeysHandler(object):
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"""
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Implements an optional realtime backup mechanism for encrypted E2E megolm room keys.
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This gives a way for users to store and recover their megolm keys if they lose all
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their clients. It should also extend easily to future room key mechanisms.
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The actual payload of the encrypted keys is completely opaque to the handler.
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"""
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def __init__(self, hs):
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self.store = hs.get_datastore()
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# Used to lock whenever a client is uploading key data. This prevents collisions
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# between clients trying to upload the details of a new session, given all
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# clients belonging to a user will receive and try to upload a new session at
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# roughly the same time. Also used to lock out uploads when the key is being
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# changed.
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self._upload_linearizer = Linearizer("upload_room_keys_lock")
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@defer.inlineCallbacks
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def get_room_keys(self, user_id, version, room_id, session_id):
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# we deliberately take the lock to get keys so that changing the version
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# works atomically
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with (yield self._upload_linearizer.queue(user_id)):
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results = yield self.store.get_e2e_room_keys(
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user_id, version, room_id, session_id
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)
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defer.returnValue(results)
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@defer.inlineCallbacks
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def delete_room_keys(self, user_id, version, room_id, session_id):
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# lock for consistency with uploading
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with (yield self._upload_linearizer.queue(user_id)):
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yield self.store.delete_e2e_room_keys(user_id, version, room_id, session_id)
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@defer.inlineCallbacks
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def upload_room_keys(self, user_id, version, room_keys):
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# TODO: Validate the JSON to make sure it has the right keys.
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# XXX: perhaps we should use a finer grained lock here?
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with (yield self._upload_linearizer.queue(user_id)):
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# Check that the version we're trying to upload is the current version
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try:
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version_info = yield self.get_version_info(user_id, version)
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except StoreError as e:
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if e.code == 404:
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raise SynapseError(404, "Version '%s' not found" % (version,))
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else:
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raise e
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if version_info['version'] != version:
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raise RoomKeysVersionError(current_version=version_info.version)
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# go through the room_keys.
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# XXX: this should/could be done concurrently, given we're in a lock.
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for room_id, room in room_keys['rooms'].iteritems():
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for session_id, session in room['sessions'].iteritems():
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room_key = session[session_id]
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yield self._upload_room_key(
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user_id, version, room_id, session_id, room_key
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)
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@defer.inlineCallbacks
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def _upload_room_key(self, user_id, version, room_id, session_id, room_key):
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# get the room_key for this particular row
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current_room_key = None
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try:
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current_room_key = yield self.store.get_e2e_room_key(
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user_id, version, room_id, session_id
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)
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except StoreError as e:
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if e.code == 404:
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pass
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else:
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raise e
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if _should_replace_room_key(current_room_key, room_key):
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yield self.store.set_e2e_room_key(
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user_id, version, room_id, session_id, room_key
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)
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def _should_replace_room_key(current_room_key, room_key):
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"""
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Determine whether to replace the current_room_key in our backup for this
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session (if any) with a new room_key that has been uploaded.
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Args:
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current_room_key (dict): Optional, the current room_key dict if any
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room_key (dict): The new room_key dict which may or may not be fit to
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replace the current_room_key
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Returns:
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True if current_room_key should be replaced by room_key in the backup
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"""
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if current_room_key:
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# spelt out with if/elifs rather than nested boolean expressions
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# purely for legibility.
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if room_key['is_verified'] and not current_room_key['is_verified']:
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pass
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elif (
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room_key['first_message_index'] <
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current_room_key['first_message_index']
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):
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pass
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elif room_key['forwarded_count'] < current_room_key['forwarded_count']:
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pass
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else:
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return False
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return True
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@defer.inlineCallbacks
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def create_version(self, user_id, version_info):
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# TODO: Validate the JSON to make sure it has the right keys.
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# lock everyone out until we've switched version
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with (yield self._upload_linearizer.queue(user_id)):
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new_version = yield self.store.create_e2e_room_keys_version(
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user_id, version_info
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)
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defer.returnValue(new_version)
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@defer.inlineCallbacks
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def get_version_info(self, user_id, version):
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with (yield self._upload_linearizer.queue(user_id)):
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results = yield self.store.get_e2e_room_keys_version_info(
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user_id, version
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)
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defer.returnValue(results)
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@defer.inlineCallbacks
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def delete_version(self, user_id, version):
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with (yield self._upload_linearizer.queue(user_id)):
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yield self.store.delete_e2e_room_keys_version(user_id, version)
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