# -*- coding: utf-8 -*-
# Copyright 2019 The Matrix.org Foundation C.I.C.
#
# 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.
import logging
import attr
import saml2
from saml2.client import Saml2Client
from synapse.api.errors import SynapseError
from synapse.http.servlet import parse_string
from synapse.rest.client.v1.login import SSOAuthHandler
from synapse.types import UserID, map_username_to_mxid_localpart
from synapse.util.async_helpers import Linearizer
logger = logging.getLogger(__name__)
class SamlHandler:
def __init__(self, hs):
self._saml_client = Saml2Client(hs.config.saml2_sp_config)
self._sso_auth_handler = SSOAuthHandler(hs)
self._registration_handler = hs.get_registration_handler()
self._clock = hs.get_clock()
self._datastore = hs.get_datastore()
self._hostname = hs.hostname
self._saml2_session_lifetime = hs.config.saml2_session_lifetime
self._mxid_source_attribute = hs.config.saml2_mxid_source_attribute
self._grandfathered_mxid_source_attribute = (
hs.config.saml2_grandfathered_mxid_source_attribute
)
self._mxid_mapper = hs.config.saml2_mxid_mapper
# identifier for the external_ids table
self._auth_provider_id = "saml"
# a map from saml session id to Saml2SessionData object
self._outstanding_requests_dict = {}
# a lock on the mappings
self._mapping_lock = Linearizer(name="saml_mapping", clock=self._clock)
def handle_redirect_request(self, client_redirect_url):
"""Handle an incoming request to /login/sso/redirect
Args:
client_redirect_url (bytes): the URL that we should redirect the
client to when everything is done
Returns:
bytes: URL to redirect to
"""
reqid, info = self._saml_client.prepare_for_authenticate(
relay_state=client_redirect_url
)
now = self._clock.time_msec()
self._outstanding_requests_dict[reqid] = Saml2SessionData(creation_time=now)
for key, value in info["headers"]:
if key == "Location":
return value
# this shouldn't happen!
raise Exception("prepare_for_authenticate didn't return a Location header")
async def handle_saml_response(self, request):
"""Handle an incoming request to /_matrix/saml2/authn_response
Args:
request (SynapseRequest): the incoming request from the browser. We'll
respond to it with a redirect.
Returns:
Deferred[none]: Completes once we have handled the request.
"""
resp_bytes = parse_string(request, "SAMLResponse", required=True)
relay_state = parse_string(request, "RelayState", required=True)
# expire outstanding sessions before parse_authn_request_response checks
# the dict.
self.expire_sessions()
user_id = await self._map_saml_response_to_user(resp_bytes)
self._sso_auth_handler.complete_sso_login(user_id, request, relay_state)
async def _map_saml_response_to_user(self, resp_bytes):
try:
saml2_auth = self._saml_client.parse_authn_request_response(
resp_bytes,
saml2.BINDING_HTTP_POST,
outstanding=self._outstanding_requests_dict,
)
except Exception as e:
logger.warning("Exception parsing SAML2 response: %s", e)
raise SynapseError(400, "Unable to parse SAML2 response: %s" % (e,))
if saml2_auth.not_signed:
logger.warning("SAML2 response was not signed")
raise SynapseError(400, "SAML2 response was not signed")
logger.info("SAML2 response: %s", saml2_auth.origxml)
logger.info("SAML2 mapped attributes: %s", saml2_auth.ava)
try:
remote_user_id = saml2_auth.ava["uid"][0]
except KeyError:
logger.warning("SAML2 response lacks a 'uid' attestation")
raise SynapseError(400, "uid not in SAML2 response")
try:
mxid_source = saml2_auth.ava[self._mxid_source_attribute][0]
except KeyError:
logger.warning(
"SAML2 response lacks a '%s' attestation", self._mxid_source_attribute
)
raise SynapseError(
400, "%s not in SAML2 response" % (self._mxid_source_attribute,)
)
self._outstanding_requests_dict.pop(saml2_auth.in_response_to, None)
displayName = saml2_auth.ava.get("displayName", [None])[0]
with (await self._mapping_lock.queue(self._auth_provider_id)):
# first of all, check if we already have a mapping for this user
logger.info(
"Looking for existing mapping for user %s:%s",
self._auth_provider_id,
remote_user_id,
)
registered_user_id = await self._datastore.get_user_by_external_id(
self._auth_provider_id, remote_user_id
)
if registered_user_id is not None:
logger.info("Found existing mapping %s", registered_user_id)
return registered_user_id
# backwards-compatibility hack: see if there is an existing user with a
# suitable mapping from the uid
if (
self._grandfathered_mxid_source_attribute
and self._grandfathered_mxid_source_attribute in saml2_auth.ava
):
attrval = saml2_auth.ava[self._grandfathered_mxid_source_attribute][0]
user_id = UserID(
map_username_to_mxid_localpart(attrval), self._hostname
).to_string()
logger.info(
"Looking for existing account based on mapped %s %s",
self._grandfathered_mxid_source_attribute,
user_id,
)
users = await self._datastore.get_users_by_id_case_insensitive(user_id)
if users:
registered_user_id = list(users.keys())[0]
logger.info("Grandfathering mapping to %s", registered_user_id)
await self._datastore.record_user_external_id(
self._auth_provider_id, remote_user_id, registered_user_id
)
return registered_user_id
# figure out a new mxid for this user
base_mxid_localpart = self._mxid_mapper(mxid_source)
suffix = 0
while True:
localpart = base_mxid_localpart + (str(suffix) if suffix else "")
if not await self._datastore.get_users_by_id_case_insensitive(
UserID(localpart, self._hostname).to_string()
):
break
suffix += 1
logger.info("Allocating mxid for new user with localpart %s", localpart)
registered_user_id = await self._registration_handler.register_user(
localpart=localpart, default_display_name=displayName
)
await self._datastore.record_user_external_id(
self._auth_provider_id, remote_user_id, registered_user_id
)
return registered_user_id
def expire_sessions(self):
expire_before = self._clock.time_msec() - self._saml2_session_lifetime
to_expire = set()
for reqid, data in self._outstanding_requests_dict.items():
if data.creation_time < expire_before:
to_expire.add(reqid)
for reqid in to_expire:
logger.debug("Expiring session id %s", reqid)
del self._outstanding_requests_dict[reqid]
@attr.s
class Saml2SessionData:
"""Data we track about SAML2 sessions"""
# time the session was created, in milliseconds
creation_time = attr.ib()