diff options
Diffstat (limited to 'synapse/groups/attestations.py')
| -rw-r--r-- | synapse/groups/attestations.py | 218 |
1 files changed, 0 insertions, 218 deletions
diff --git a/synapse/groups/attestations.py b/synapse/groups/attestations.py deleted file mode 100644 index ed26d6a6ce..0000000000 --- a/synapse/groups/attestations.py +++ /dev/null @@ -1,218 +0,0 @@ -# Copyright 2017 Vector Creations 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. - -"""Attestations ensure that users and groups can't lie about their memberships. - -When a user joins a group the HS and GS swap attestations, which allow them -both to independently prove to third parties their membership.These -attestations have a validity period so need to be periodically renewed. - -If a user leaves (or gets kicked out of) a group, either side can still use -their attestation to "prove" their membership, until the attestation expires. -Therefore attestations shouldn't be relied on to prove membership in important -cases, but can for less important situations, e.g. showing a users membership -of groups on their profile, showing flairs, etc. - -An attestation is a signed blob of json that looks like: - - { - "user_id": "@foo:a.example.com", - "group_id": "+bar:b.example.com", - "valid_until_ms": 1507994728530, - "signatures":{"matrix.org":{"ed25519:auto":"..."}} - } -""" - -import logging -import random -from typing import TYPE_CHECKING, Optional, Tuple - -from signedjson.sign import sign_json - -from twisted.internet.defer import Deferred - -from synapse.api.errors import HttpResponseException, RequestSendFailed, SynapseError -from synapse.metrics.background_process_metrics import run_as_background_process -from synapse.types import JsonDict, get_domain_from_id - -if TYPE_CHECKING: - from synapse.server import HomeServer - -logger = logging.getLogger(__name__) - - -# Default validity duration for new attestations we create -DEFAULT_ATTESTATION_LENGTH_MS = 3 * 24 * 60 * 60 * 1000 - -# We add some jitter to the validity duration of attestations so that if we -# add lots of users at once we don't need to renew them all at once. -# The jitter is a multiplier picked randomly between the first and second number -DEFAULT_ATTESTATION_JITTER = (0.9, 1.3) - -# Start trying to update our attestations when they come this close to expiring -UPDATE_ATTESTATION_TIME_MS = 1 * 24 * 60 * 60 * 1000 - - -class GroupAttestationSigning: - """Creates and verifies group attestations.""" - - def __init__(self, hs: "HomeServer"): - self.keyring = hs.get_keyring() - self.clock = hs.get_clock() - self.server_name = hs.hostname - self.signing_key = hs.signing_key - - async def verify_attestation( - self, - attestation: JsonDict, - group_id: str, - user_id: str, - server_name: Optional[str] = None, - ) -> None: - """Verifies that the given attestation matches the given parameters. - - An optional server_name can be supplied to explicitly set which server's - signature is expected. Otherwise assumes that either the group_id or user_id - is local and uses the other's server as the one to check. - """ - - if not server_name: - if get_domain_from_id(group_id) == self.server_name: - server_name = get_domain_from_id(user_id) - elif get_domain_from_id(user_id) == self.server_name: - server_name = get_domain_from_id(group_id) - else: - raise Exception("Expected either group_id or user_id to be local") - - if user_id != attestation["user_id"]: - raise SynapseError(400, "Attestation has incorrect user_id") - - if group_id != attestation["group_id"]: - raise SynapseError(400, "Attestation has incorrect group_id") - valid_until_ms = attestation["valid_until_ms"] - - # TODO: We also want to check that *new* attestations that people give - # us to store are valid for at least a little while. - now = self.clock.time_msec() - if valid_until_ms < now: - raise SynapseError(400, "Attestation expired") - - assert server_name is not None - await self.keyring.verify_json_for_server( - server_name, - attestation, - now, - ) - - def create_attestation(self, group_id: str, user_id: str) -> JsonDict: - """Create an attestation for the group_id and user_id with default - validity length. - """ - validity_period = DEFAULT_ATTESTATION_LENGTH_MS * random.uniform( - *DEFAULT_ATTESTATION_JITTER - ) - valid_until_ms = int(self.clock.time_msec() + validity_period) - - return sign_json( - { - "group_id": group_id, - "user_id": user_id, - "valid_until_ms": valid_until_ms, - }, - self.server_name, - self.signing_key, - ) - - -class GroupAttestionRenewer: - """Responsible for sending and receiving attestation updates.""" - - def __init__(self, hs: "HomeServer"): - self.clock = hs.get_clock() - self.store = hs.get_datastores().main - self.assestations = hs.get_groups_attestation_signing() - self.transport_client = hs.get_federation_transport_client() - self.is_mine_id = hs.is_mine_id - self.attestations = hs.get_groups_attestation_signing() - - if not hs.config.worker.worker_app: - self._renew_attestations_loop = self.clock.looping_call( - self._start_renew_attestations, 30 * 60 * 1000 - ) - - async def on_renew_attestation( - self, group_id: str, user_id: str, content: JsonDict - ) -> JsonDict: - """When a remote updates an attestation""" - attestation = content["attestation"] - - if not self.is_mine_id(group_id) and not self.is_mine_id(user_id): - raise SynapseError(400, "Neither user not group are on this server") - - await self.attestations.verify_attestation( - attestation, user_id=user_id, group_id=group_id - ) - - await self.store.update_remote_attestion(group_id, user_id, attestation) - - return {} - - def _start_renew_attestations(self) -> "Deferred[None]": - return run_as_background_process("renew_attestations", self._renew_attestations) - - async def _renew_attestations(self) -> None: - """Called periodically to check if we need to update any of our attestations""" - - now = self.clock.time_msec() - - rows = await self.store.get_attestations_need_renewals( - now + UPDATE_ATTESTATION_TIME_MS - ) - - async def _renew_attestation(group_user: Tuple[str, str]) -> None: - group_id, user_id = group_user - try: - if not self.is_mine_id(group_id): - destination = get_domain_from_id(group_id) - elif not self.is_mine_id(user_id): - destination = get_domain_from_id(user_id) - else: - logger.warning( - "Incorrectly trying to do attestations for user: %r in %r", - user_id, - group_id, - ) - await self.store.remove_attestation_renewal(group_id, user_id) - return - - attestation = self.attestations.create_attestation(group_id, user_id) - - await self.transport_client.renew_group_attestation( - destination, group_id, user_id, content={"attestation": attestation} - ) - - await self.store.update_attestation_renewal( - group_id, user_id, attestation - ) - except (RequestSendFailed, HttpResponseException) as e: - logger.warning( - "Failed to renew attestation of %r in %r: %s", user_id, group_id, e - ) - except Exception: - logger.exception( - "Error renewing attestation of %r in %r", user_id, group_id - ) - - for row in rows: - await _renew_attestation((row["group_id"], row["user_id"])) |