From a5e2941aad9acdd5033709807bb6ddd40e4435eb Mon Sep 17 00:00:00 2001 From: Richard van der Hoff Date: Tue, 22 May 2018 08:56:52 +0100 Subject: [PATCH] Reject attempts to send event before privacy consent is given Returns an M_CONSENT_NOT_GIVEN error (cf https://github.com/matrix-org/matrix-doc/issues/1252) if consent is not yet given. --- synapse/api/errors.py | 30 ++++++++++- synapse/api/urls.py | 50 +++++++++++++++++++ synapse/config/consent_config.py | 10 ++++ synapse/handlers/message.py | 86 +++++++++++++++++++++++++++++++- synapse/handlers/room.py | 4 ++ tests/utils.py | 1 + 6 files changed, 179 insertions(+), 2 deletions(-) diff --git a/synapse/api/errors.py b/synapse/api/errors.py index a9ff5576f..aca804280 100644 --- a/synapse/api/errors.py +++ b/synapse/api/errors.py @@ -19,6 +19,7 @@ import logging import simplejson as json from six import iteritems +from six.moves import http_client logger = logging.getLogger(__name__) @@ -51,6 +52,7 @@ class Codes(object): THREEPID_DENIED = "M_THREEPID_DENIED" INVALID_USERNAME = "M_INVALID_USERNAME" SERVER_NOT_TRUSTED = "M_SERVER_NOT_TRUSTED" + CONSENT_NOT_GIVEN = "M_CONSENT_NOT_GIVEN" class CodeMessageException(RuntimeError): @@ -138,6 +140,32 @@ class SynapseError(CodeMessageException): return res +class ConsentNotGivenError(SynapseError): + """The error returned to the client when the user has not consented to the + privacy policy. + """ + def __init__(self, msg, consent_uri): + """Constructs a ConsentNotGivenError + + Args: + msg (str): The human-readable error message + consent_url (str): The URL where the user can give their consent + """ + super(ConsentNotGivenError, self).__init__( + code=http_client.FORBIDDEN, + msg=msg, + errcode=Codes.CONSENT_NOT_GIVEN + ) + self._consent_uri = consent_uri + + def error_dict(self): + return cs_error( + self.msg, + self.errcode, + consent_uri=self._consent_uri + ) + + class RegistrationError(SynapseError): """An error raised when a registration event fails.""" pass @@ -292,7 +320,7 @@ def cs_error(msg, code=Codes.UNKNOWN, **kwargs): Args: msg (str): The error message. - code (int): The error code. + code (str): The error code. kwargs : Additional keys to add to the response. Returns: A dict representing the error response JSON. diff --git a/synapse/api/urls.py b/synapse/api/urls.py index 91a33a340..bb46b5da8 100644 --- a/synapse/api/urls.py +++ b/synapse/api/urls.py @@ -1,5 +1,6 @@ # -*- coding: utf-8 -*- # Copyright 2014-2016 OpenMarket Ltd +# Copyright 2018 New Vector Ltd. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. @@ -14,6 +15,12 @@ # limitations under the License. """Contains the URL paths to prefix various aspects of the server with. """ +from hashlib import sha256 +import hmac + +from six.moves.urllib.parse import urlencode + +from synapse.config import ConfigError CLIENT_PREFIX = "/_matrix/client/api/v1" CLIENT_V2_ALPHA_PREFIX = "/_matrix/client/v2_alpha" @@ -25,3 +32,46 @@ SERVER_KEY_PREFIX = "/_matrix/key/v1" SERVER_KEY_V2_PREFIX = "/_matrix/key/v2" MEDIA_PREFIX = "/_matrix/media/r0" LEGACY_MEDIA_PREFIX = "/_matrix/media/v1" + + +class ConsentURIBuilder(object): + def __init__(self, hs_config): + """ + Args: + hs_config (synapse.config.homeserver.HomeServerConfig): + """ + if hs_config.form_secret is None: + raise ConfigError( + "form_secret not set in config", + ) + if hs_config.public_baseurl is None: + raise ConfigError( + "public_baseurl not set in config", + ) + + self._hmac_secret = hs_config.form_secret.encode("utf-8") + self._public_baseurl = hs_config.public_baseurl + + def build_user_consent_uri(self, user_id): + """Build a URI which we can give to the user to do their privacy + policy consent + + Args: + user_id (str): mxid or username of user + + Returns + (str) the URI where the user can do consent + """ + mac = hmac.new( + key=self._hmac_secret, + msg=user_id, + digestmod=sha256, + ).hexdigest() + consent_uri = "%s_matrix/consent?%s" % ( + self._public_baseurl, + urlencode({ + "u": user_id, + "h": mac + }), + ) + return consent_uri diff --git a/synapse/config/consent_config.py b/synapse/config/consent_config.py index 8698b2993..44c4711e6 100644 --- a/synapse/config/consent_config.py +++ b/synapse/config/consent_config.py @@ -34,6 +34,10 @@ DEFAULT_CONFIG = """\ # asking them to consent to the privacy policy. The 'server_notices' section # must also be configured for this to work. # +# 'block_events_error', if set, will block any attempts to send events +# until the user consents to the privacy policy. The value of the setting is +# used as the text of the error. +# # user_consent: # template_dir: res/templates/privacy # version: 1.0 @@ -41,6 +45,8 @@ DEFAULT_CONFIG = """\ # msgtype: m.text # body: | # Pls do consent kthx +# block_events_error: | +# You can't send any messages until you consent to the privacy policy. """ @@ -51,6 +57,7 @@ class ConsentConfig(Config): self.user_consent_version = None self.user_consent_template_dir = None self.user_consent_server_notice_content = None + self.block_events_without_consent_error = None def read_config(self, config): consent_config = config.get("user_consent") @@ -61,6 +68,9 @@ class ConsentConfig(Config): self.user_consent_server_notice_content = consent_config.get( "server_notice_content", ) + self.block_events_without_consent_error = consent_config.get( + "block_events_error", + ) def default_config(self, **kwargs): return DEFAULT_CONFIG diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py index 8343b5839..c3adbc6c9 100644 --- a/synapse/handlers/message.py +++ b/synapse/handlers/message.py @@ -20,10 +20,15 @@ import sys from canonicaljson import encode_canonical_json import six from twisted.internet import defer, reactor +from twisted.internet.defer import succeed from twisted.python.failure import Failure from synapse.api.constants import EventTypes, Membership, MAX_DEPTH -from synapse.api.errors import AuthError, Codes, SynapseError +from synapse.api.errors import ( + AuthError, Codes, SynapseError, + ConsentNotGivenError, +) +from synapse.api.urls import ConsentURIBuilder from synapse.crypto.event_signing import add_hashes_and_signatures from synapse.events.utils import serialize_event from synapse.events.validator import EventValidator @@ -431,6 +436,9 @@ class EventCreationHandler(object): self.spam_checker = hs.get_spam_checker() + if self.config.block_events_without_consent_error is not None: + self._consent_uri_builder = ConsentURIBuilder(self.config) + @defer.inlineCallbacks def create_event(self, requester, event_dict, token_id=None, txn_id=None, prev_events_and_hashes=None): @@ -482,6 +490,10 @@ class EventCreationHandler(object): target, e ) + is_exempt = yield self._is_exempt_from_privacy_policy(builder) + if not is_exempt: + yield self.assert_accepted_privacy_policy(requester) + if token_id is not None: builder.internal_metadata.token_id = token_id @@ -496,6 +508,78 @@ class EventCreationHandler(object): defer.returnValue((event, context)) + def _is_exempt_from_privacy_policy(self, builder): + """"Determine if an event to be sent is exempt from having to consent + to the privacy policy + + Args: + builder (synapse.events.builder.EventBuilder): event being created + + Returns: + Deferred[bool]: true if the event can be sent without the user + consenting + """ + # the only thing the user can do is join the server notices room. + if builder.type == EventTypes.Member: + membership = builder.content.get("membership", None) + if membership == Membership.JOIN: + return self._is_server_notices_room(builder.room_id) + return succeed(False) + + @defer.inlineCallbacks + def _is_server_notices_room(self, room_id): + if self.config.server_notices_mxid is None: + defer.returnValue(False) + user_ids = yield self.store.get_users_in_room(room_id) + defer.returnValue(self.config.server_notices_mxid in user_ids) + + @defer.inlineCallbacks + def assert_accepted_privacy_policy(self, requester): + """Check if a user has accepted the privacy policy + + Called when the given user is about to do something that requires + privacy consent. We see if the user is exempt and otherwise check that + they have given consent. If they have not, a ConsentNotGiven error is + raised. + + Args: + requester (synapse.types.Requester): + The user making the request + + Returns: + Deferred[None]: returns normally if the user has consented or is + exempt + + Raises: + ConsentNotGivenError: if the user has not given consent yet + """ + if self.config.block_events_without_consent_error is None: + return + + # exempt AS users from needing consent + if requester.app_service is not None: + return + + user_id = requester.user.to_string() + + # exempt the system notices user + if ( + self.config.server_notices_mxid is not None and + user_id == self.config.server_notices_mxid + ): + return + + u = yield self.store.get_user_by_id(user_id) + assert u is not None + if u["consent_version"] == self.config.user_consent_version: + return + + consent_uri = self._consent_uri_builder.build_user_consent_uri(user_id) + raise ConsentNotGivenError( + msg=self.config.block_events_without_consent_error, + consent_uri=consent_uri, + ) + @defer.inlineCallbacks def send_nonmember_event(self, requester, event, context, ratelimit=True): """ diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py index 5e9fa95a2..b5850db42 100644 --- a/synapse/handlers/room.py +++ b/synapse/handlers/room.py @@ -126,6 +126,10 @@ class RoomCreationHandler(BaseHandler): except Exception: raise SynapseError(400, "Invalid user_id: %s" % (i,)) + yield self.event_creation_handler.assert_accepted_privacy_policy( + requester, + ) + invite_3pid_list = config.get("invite_3pid", []) visibility = config.get("visibility", None) diff --git a/tests/utils.py b/tests/utils.py index 9626e6fd7..262c4a571 100644 --- a/tests/utils.py +++ b/tests/utils.py @@ -64,6 +64,7 @@ def setup_test_homeserver(name="test", datastore=None, config=None, **kargs): config.filter_timeline_limit = 5000 config.user_directory_search_all_users = False config.user_consent_server_notice_content = None + config.block_events_without_consent_error = None # disable user directory updates, because they get done in the # background, which upsets the test runner.