366 lines
13 KiB
Python
366 lines
13 KiB
Python
# -*- 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 re
|
|
from typing import Tuple
|
|
|
|
import attr
|
|
import saml2
|
|
import saml2.response
|
|
from saml2.client import Saml2Client
|
|
|
|
from synapse.api.errors import SynapseError
|
|
from synapse.config import ConfigError
|
|
from synapse.http.servlet import parse_string
|
|
from synapse.module_api import ModuleApi
|
|
from synapse.rest.client.v1.login import SSOAuthHandler
|
|
from synapse.types import (
|
|
UserID,
|
|
map_username_to_mxid_localpart,
|
|
mxid_localpart_allowed_characters,
|
|
)
|
|
from synapse.util.async_helpers import Linearizer
|
|
|
|
logger = logging.getLogger(__name__)
|
|
|
|
|
|
@attr.s
|
|
class Saml2SessionData:
|
|
"""Data we track about SAML2 sessions"""
|
|
|
|
# time the session was created, in milliseconds
|
|
creation_time = attr.ib()
|
|
|
|
|
|
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._grandfathered_mxid_source_attribute = (
|
|
hs.config.saml2_grandfathered_mxid_source_attribute
|
|
)
|
|
|
|
# plugin to do custom mapping from saml response to mxid
|
|
self._user_mapping_provider = hs.config.saml2_user_mapping_provider_class(
|
|
hs.config.saml2_user_mapping_provider_config,
|
|
ModuleApi(hs, hs.get_auth_handler()),
|
|
)
|
|
|
|
# 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, relay_state)
|
|
self._sso_auth_handler.complete_sso_login(user_id, request, relay_state)
|
|
|
|
async def _map_saml_response_to_user(self, resp_bytes, client_redirect_url):
|
|
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")
|
|
|
|
self._outstanding_requests_dict.pop(saml2_auth.in_response_to, None)
|
|
|
|
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
|
|
|
|
# Map saml response to user attributes using the configured mapping provider
|
|
for i in range(1000):
|
|
attribute_dict = self._user_mapping_provider.saml_response_to_user_attributes(
|
|
saml2_auth, i, client_redirect_url=client_redirect_url,
|
|
)
|
|
|
|
logger.debug(
|
|
"Retrieved SAML attributes from user mapping provider: %s "
|
|
"(attempt %d)",
|
|
attribute_dict,
|
|
i,
|
|
)
|
|
|
|
localpart = attribute_dict.get("mxid_localpart")
|
|
if not localpart:
|
|
logger.error(
|
|
"SAML mapping provider plugin did not return a "
|
|
"mxid_localpart object"
|
|
)
|
|
raise SynapseError(500, "Error parsing SAML2 response")
|
|
|
|
displayname = attribute_dict.get("displayname")
|
|
|
|
# Check if this mxid already exists
|
|
if not await self._datastore.get_users_by_id_case_insensitive(
|
|
UserID(localpart, self._hostname).to_string()
|
|
):
|
|
# This mxid is free
|
|
break
|
|
else:
|
|
# Unable to generate a username in 1000 iterations
|
|
# Break and return error to the user
|
|
raise SynapseError(
|
|
500, "Unable to generate a Matrix ID from the SAML response"
|
|
)
|
|
|
|
logger.info("Mapped SAML user to local part %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]
|
|
|
|
|
|
DOT_REPLACE_PATTERN = re.compile(
|
|
("[^%s]" % (re.escape("".join(mxid_localpart_allowed_characters)),))
|
|
)
|
|
|
|
|
|
def dot_replace_for_mxid(username: str) -> str:
|
|
username = username.lower()
|
|
username = DOT_REPLACE_PATTERN.sub(".", username)
|
|
|
|
# regular mxids aren't allowed to start with an underscore either
|
|
username = re.sub("^_", "", username)
|
|
return username
|
|
|
|
|
|
MXID_MAPPER_MAP = {
|
|
"hexencode": map_username_to_mxid_localpart,
|
|
"dotreplace": dot_replace_for_mxid,
|
|
}
|
|
|
|
|
|
@attr.s
|
|
class SamlConfig(object):
|
|
mxid_source_attribute = attr.ib()
|
|
mxid_mapper = attr.ib()
|
|
|
|
|
|
class DefaultSamlMappingProvider(object):
|
|
__version__ = "0.0.1"
|
|
|
|
def __init__(self, parsed_config: SamlConfig, module_api: ModuleApi):
|
|
"""The default SAML user mapping provider
|
|
|
|
Args:
|
|
parsed_config: Module configuration
|
|
module_api: module api proxy
|
|
"""
|
|
self._mxid_source_attribute = parsed_config.mxid_source_attribute
|
|
self._mxid_mapper = parsed_config.mxid_mapper
|
|
|
|
def saml_response_to_user_attributes(
|
|
self,
|
|
saml_response: saml2.response.AuthnResponse,
|
|
failures: int,
|
|
client_redirect_url: str,
|
|
) -> dict:
|
|
"""Maps some text from a SAML response to attributes of a new user
|
|
|
|
Args:
|
|
saml_response: A SAML auth response object
|
|
|
|
failures: How many times a call to this function with this
|
|
saml_response has resulted in a failure
|
|
|
|
client_redirect_url: where the client wants to redirect to
|
|
|
|
Returns:
|
|
dict: A dict containing new user attributes. Possible keys:
|
|
* mxid_localpart (str): Required. The localpart of the user's mxid
|
|
* displayname (str): The displayname of the user
|
|
"""
|
|
try:
|
|
mxid_source = saml_response.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,)
|
|
)
|
|
|
|
# Use the configured mapper for this mxid_source
|
|
base_mxid_localpart = self._mxid_mapper(mxid_source)
|
|
|
|
# Append suffix integer if last call to this function failed to produce
|
|
# a usable mxid
|
|
localpart = base_mxid_localpart + (str(failures) if failures else "")
|
|
|
|
# Retrieve the display name from the saml response
|
|
# If displayname is None, the mxid_localpart will be used instead
|
|
displayname = saml_response.ava.get("displayName", [None])[0]
|
|
|
|
return {
|
|
"mxid_localpart": localpart,
|
|
"displayname": displayname,
|
|
}
|
|
|
|
@staticmethod
|
|
def parse_config(config: dict) -> SamlConfig:
|
|
"""Parse the dict provided by the homeserver's config
|
|
Args:
|
|
config: A dictionary containing configuration options for this provider
|
|
Returns:
|
|
SamlConfig: A custom config object for this module
|
|
"""
|
|
# Parse config options and use defaults where necessary
|
|
mxid_source_attribute = config.get("mxid_source_attribute", "uid")
|
|
mapping_type = config.get("mxid_mapping", "hexencode")
|
|
|
|
# Retrieve the associating mapping function
|
|
try:
|
|
mxid_mapper = MXID_MAPPER_MAP[mapping_type]
|
|
except KeyError:
|
|
raise ConfigError(
|
|
"saml2_config.user_mapping_provider.config: '%s' is not a valid "
|
|
"mxid_mapping value" % (mapping_type,)
|
|
)
|
|
|
|
return SamlConfig(mxid_source_attribute, mxid_mapper)
|
|
|
|
@staticmethod
|
|
def get_saml_attributes(config: SamlConfig) -> Tuple[set, set]:
|
|
"""Returns the required attributes of a SAML
|
|
|
|
Args:
|
|
config: A SamlConfig object containing configuration params for this provider
|
|
|
|
Returns:
|
|
tuple[set,set]: The first set equates to the saml auth response
|
|
attributes that are required for the module to function, whereas the
|
|
second set consists of those attributes which can be used if
|
|
available, but are not necessary
|
|
"""
|
|
return {"uid", config.mxid_source_attribute}, {"displayName"}
|