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aec294ee0d
slots use less memory (and attribute access is faster) while slightly limiting the flexibility of the class attributes. This focuses on objects which are instantiated "often" and for short periods of time.
535 lines
20 KiB
Python
535 lines
20 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2019 The Matrix.org Foundation C.I.C.
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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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import re
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from typing import TYPE_CHECKING, Callable, Dict, Optional, Set, Tuple
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import attr
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import saml2
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import saml2.response
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from saml2.client import Saml2Client
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from synapse.api.errors import SynapseError
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from synapse.config import ConfigError
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from synapse.config.saml2_config import SamlAttributeRequirement
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from synapse.http.server import respond_with_html
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from synapse.http.servlet import parse_string
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from synapse.http.site import SynapseRequest
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from synapse.module_api import ModuleApi
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from synapse.types import (
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UserID,
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map_username_to_mxid_localpart,
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mxid_localpart_allowed_characters,
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)
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from synapse.util.async_helpers import Linearizer
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from synapse.util.iterutils import chunk_seq
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if TYPE_CHECKING:
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import synapse.server
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logger = logging.getLogger(__name__)
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class MappingException(Exception):
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"""Used to catch errors when mapping the SAML2 response to a user."""
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@attr.s(slots=True)
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class Saml2SessionData:
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"""Data we track about SAML2 sessions"""
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# time the session was created, in milliseconds
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creation_time = attr.ib()
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# The user interactive authentication session ID associated with this SAML
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# session (or None if this SAML session is for an initial login).
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ui_auth_session_id = attr.ib(type=Optional[str], default=None)
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class SamlHandler:
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def __init__(self, hs: "synapse.server.HomeServer"):
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self.hs = hs
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self._saml_client = Saml2Client(hs.config.saml2_sp_config)
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self._auth = hs.get_auth()
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self._auth_handler = hs.get_auth_handler()
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self._registration_handler = hs.get_registration_handler()
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self._clock = hs.get_clock()
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self._datastore = hs.get_datastore()
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self._hostname = hs.hostname
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self._saml2_session_lifetime = hs.config.saml2_session_lifetime
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self._grandfathered_mxid_source_attribute = (
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hs.config.saml2_grandfathered_mxid_source_attribute
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)
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self._saml2_attribute_requirements = hs.config.saml2.attribute_requirements
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self._error_template = hs.config.sso_error_template
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# plugin to do custom mapping from saml response to mxid
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self._user_mapping_provider = hs.config.saml2_user_mapping_provider_class(
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hs.config.saml2_user_mapping_provider_config,
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ModuleApi(hs, hs.get_auth_handler()),
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)
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# identifier for the external_ids table
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self._auth_provider_id = "saml"
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# a map from saml session id to Saml2SessionData object
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self._outstanding_requests_dict = {} # type: Dict[str, Saml2SessionData]
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# a lock on the mappings
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self._mapping_lock = Linearizer(name="saml_mapping", clock=self._clock)
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def _render_error(
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self, request, error: str, error_description: Optional[str] = None
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) -> None:
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"""Render the error template and respond to the request with it.
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This is used to show errors to the user. The template of this page can
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be found under `synapse/res/templates/sso_error.html`.
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Args:
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request: The incoming request from the browser.
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We'll respond with an HTML page describing the error.
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error: A technical identifier for this error.
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error_description: A human-readable description of the error.
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"""
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html = self._error_template.render(
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error=error, error_description=error_description
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)
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respond_with_html(request, 400, html)
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def handle_redirect_request(
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self, client_redirect_url: bytes, ui_auth_session_id: Optional[str] = None
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) -> bytes:
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"""Handle an incoming request to /login/sso/redirect
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Args:
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client_redirect_url: the URL that we should redirect the
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client to when everything is done
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ui_auth_session_id: The session ID of the ongoing UI Auth (or
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None if this is a login).
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Returns:
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URL to redirect to
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"""
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reqid, info = self._saml_client.prepare_for_authenticate(
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relay_state=client_redirect_url
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)
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# Since SAML sessions timeout it is useful to log when they were created.
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logger.info("Initiating a new SAML session: %s" % (reqid,))
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now = self._clock.time_msec()
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self._outstanding_requests_dict[reqid] = Saml2SessionData(
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creation_time=now, ui_auth_session_id=ui_auth_session_id,
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)
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for key, value in info["headers"]:
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if key == "Location":
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return value
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# this shouldn't happen!
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raise Exception("prepare_for_authenticate didn't return a Location header")
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async def handle_saml_response(self, request: SynapseRequest) -> None:
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"""Handle an incoming request to /_matrix/saml2/authn_response
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Args:
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request: the incoming request from the browser. We'll
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respond to it with a redirect.
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Returns:
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Completes once we have handled the request.
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"""
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resp_bytes = parse_string(request, "SAMLResponse", required=True)
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relay_state = parse_string(request, "RelayState", required=True)
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# expire outstanding sessions before parse_authn_request_response checks
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# the dict.
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self.expire_sessions()
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try:
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saml2_auth = self._saml_client.parse_authn_request_response(
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resp_bytes,
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saml2.BINDING_HTTP_POST,
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outstanding=self._outstanding_requests_dict,
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)
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except saml2.response.UnsolicitedResponse as e:
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# the pysaml2 library helpfully logs an ERROR here, but neglects to log
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# the session ID. I don't really want to put the full text of the exception
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# in the (user-visible) exception message, so let's log the exception here
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# so we can track down the session IDs later.
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logger.warning(str(e))
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self._render_error(
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request, "unsolicited_response", "Unexpected SAML2 login."
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)
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return
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except Exception as e:
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self._render_error(
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request,
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"invalid_response",
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"Unable to parse SAML2 response: %s." % (e,),
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)
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return
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if saml2_auth.not_signed:
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self._render_error(
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request, "unsigned_respond", "SAML2 response was not signed."
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)
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return
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logger.debug("SAML2 response: %s", saml2_auth.origxml)
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for assertion in saml2_auth.assertions:
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# kibana limits the length of a log field, whereas this is all rather
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# useful, so split it up.
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count = 0
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for part in chunk_seq(str(assertion), 10000):
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logger.info(
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"SAML2 assertion: %s%s", "(%i)..." % (count,) if count else "", part
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)
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count += 1
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logger.info("SAML2 mapped attributes: %s", saml2_auth.ava)
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current_session = self._outstanding_requests_dict.pop(
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saml2_auth.in_response_to, None
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)
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# Ensure that the attributes of the logged in user meet the required
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# attributes.
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for requirement in self._saml2_attribute_requirements:
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if not _check_attribute_requirement(saml2_auth.ava, requirement):
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self._render_error(
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request, "unauthorised", "You are not authorised to log in here."
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)
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return
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# Pull out the user-agent and IP from the request.
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user_agent = request.requestHeaders.getRawHeaders(b"User-Agent", default=[b""])[
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0
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].decode("ascii", "surrogateescape")
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ip_address = self.hs.get_ip_from_request(request)
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# Call the mapper to register/login the user
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try:
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user_id = await self._map_saml_response_to_user(
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saml2_auth, relay_state, user_agent, ip_address
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)
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except MappingException as e:
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logger.exception("Could not map user")
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self._render_error(request, "mapping_error", str(e))
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return
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# Complete the interactive auth session or the login.
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if current_session and current_session.ui_auth_session_id:
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await self._auth_handler.complete_sso_ui_auth(
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user_id, current_session.ui_auth_session_id, request
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)
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else:
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await self._auth_handler.complete_sso_login(user_id, request, relay_state)
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async def _map_saml_response_to_user(
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self,
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saml2_auth: saml2.response.AuthnResponse,
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client_redirect_url: str,
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user_agent: str,
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ip_address: str,
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) -> str:
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"""
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Given a SAML response, retrieve the user ID for it and possibly register the user.
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Args:
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saml2_auth: The parsed SAML2 response.
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client_redirect_url: The redirect URL passed in by the client.
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user_agent: The user agent of the client making the request.
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ip_address: The IP address of the client making the request.
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Returns:
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The user ID associated with this response.
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Raises:
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MappingException if there was a problem mapping the response to a user.
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RedirectException: some mapping providers may raise this if they need
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to redirect to an interstitial page.
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"""
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remote_user_id = self._user_mapping_provider.get_remote_user_id(
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saml2_auth, client_redirect_url
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)
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if not remote_user_id:
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raise MappingException(
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"Failed to extract remote user id from SAML response"
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)
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with (await self._mapping_lock.queue(self._auth_provider_id)):
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# first of all, check if we already have a mapping for this user
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logger.info(
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"Looking for existing mapping for user %s:%s",
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self._auth_provider_id,
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remote_user_id,
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)
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registered_user_id = await self._datastore.get_user_by_external_id(
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self._auth_provider_id, remote_user_id
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)
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if registered_user_id is not None:
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logger.info("Found existing mapping %s", registered_user_id)
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return registered_user_id
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# backwards-compatibility hack: see if there is an existing user with a
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# suitable mapping from the uid
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if (
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self._grandfathered_mxid_source_attribute
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and self._grandfathered_mxid_source_attribute in saml2_auth.ava
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):
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attrval = saml2_auth.ava[self._grandfathered_mxid_source_attribute][0]
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user_id = UserID(
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map_username_to_mxid_localpart(attrval), self._hostname
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).to_string()
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logger.info(
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"Looking for existing account based on mapped %s %s",
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self._grandfathered_mxid_source_attribute,
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user_id,
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)
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users = await self._datastore.get_users_by_id_case_insensitive(user_id)
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if users:
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registered_user_id = list(users.keys())[0]
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logger.info("Grandfathering mapping to %s", registered_user_id)
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await self._datastore.record_user_external_id(
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self._auth_provider_id, remote_user_id, registered_user_id
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)
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return registered_user_id
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# Map saml response to user attributes using the configured mapping provider
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for i in range(1000):
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attribute_dict = self._user_mapping_provider.saml_response_to_user_attributes(
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saml2_auth, i, client_redirect_url=client_redirect_url,
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)
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logger.debug(
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"Retrieved SAML attributes from user mapping provider: %s "
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"(attempt %d)",
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attribute_dict,
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i,
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)
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localpart = attribute_dict.get("mxid_localpart")
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if not localpart:
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raise MappingException(
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"Error parsing SAML2 response: SAML mapping provider plugin "
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"did not return a mxid_localpart value"
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)
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displayname = attribute_dict.get("displayname")
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emails = attribute_dict.get("emails", [])
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# Check if this mxid already exists
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if not await self._datastore.get_users_by_id_case_insensitive(
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UserID(localpart, self._hostname).to_string()
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):
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# This mxid is free
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break
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else:
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# Unable to generate a username in 1000 iterations
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# Break and return error to the user
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raise MappingException(
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"Unable to generate a Matrix ID from the SAML response"
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)
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logger.info("Mapped SAML user to local part %s", localpart)
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registered_user_id = await self._registration_handler.register_user(
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localpart=localpart,
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default_display_name=displayname,
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bind_emails=emails,
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user_agent_ips=(user_agent, ip_address),
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)
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await self._datastore.record_user_external_id(
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self._auth_provider_id, remote_user_id, registered_user_id
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)
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return registered_user_id
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def expire_sessions(self):
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expire_before = self._clock.time_msec() - self._saml2_session_lifetime
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to_expire = set()
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for reqid, data in self._outstanding_requests_dict.items():
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if data.creation_time < expire_before:
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to_expire.add(reqid)
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for reqid in to_expire:
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logger.debug("Expiring session id %s", reqid)
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del self._outstanding_requests_dict[reqid]
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def _check_attribute_requirement(ava: dict, req: SamlAttributeRequirement) -> bool:
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values = ava.get(req.attribute, [])
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for v in values:
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if v == req.value:
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return True
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logger.info(
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"SAML2 attribute %s did not match required value '%s' (was '%s')",
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req.attribute,
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req.value,
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values,
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)
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return False
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DOT_REPLACE_PATTERN = re.compile(
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("[^%s]" % (re.escape("".join(mxid_localpart_allowed_characters)),))
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)
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def dot_replace_for_mxid(username: str) -> str:
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"""Replace any characters which are not allowed in Matrix IDs with a dot."""
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username = username.lower()
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username = DOT_REPLACE_PATTERN.sub(".", username)
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# regular mxids aren't allowed to start with an underscore either
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username = re.sub("^_", "", username)
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return username
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MXID_MAPPER_MAP = {
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"hexencode": map_username_to_mxid_localpart,
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"dotreplace": dot_replace_for_mxid,
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} # type: Dict[str, Callable[[str], str]]
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@attr.s
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class SamlConfig:
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mxid_source_attribute = attr.ib()
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mxid_mapper = attr.ib()
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class DefaultSamlMappingProvider:
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__version__ = "0.0.1"
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def __init__(self, parsed_config: SamlConfig, module_api: ModuleApi):
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"""The default SAML user mapping provider
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Args:
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parsed_config: Module configuration
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module_api: module api proxy
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"""
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self._mxid_source_attribute = parsed_config.mxid_source_attribute
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self._mxid_mapper = parsed_config.mxid_mapper
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self._grandfathered_mxid_source_attribute = (
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module_api._hs.config.saml2_grandfathered_mxid_source_attribute
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)
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def get_remote_user_id(
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self, saml_response: saml2.response.AuthnResponse, client_redirect_url: str
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) -> str:
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"""Extracts the remote user id from the SAML response"""
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try:
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return saml_response.ava["uid"][0]
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except KeyError:
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logger.warning("SAML2 response lacks a 'uid' attestation")
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raise MappingException("'uid' not in SAML2 response")
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def saml_response_to_user_attributes(
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self,
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saml_response: saml2.response.AuthnResponse,
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failures: int,
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client_redirect_url: str,
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) -> dict:
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"""Maps some text from a SAML response to attributes of a new user
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Args:
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saml_response: A SAML auth response object
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failures: How many times a call to this function with this
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saml_response has resulted in a failure
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client_redirect_url: where the client wants to redirect to
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Returns:
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dict: A dict containing new user attributes. Possible keys:
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* mxid_localpart (str): Required. The localpart of the user's mxid
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* displayname (str): The displayname of the user
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* emails (list[str]): Any emails for the user
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"""
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try:
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mxid_source = saml_response.ava[self._mxid_source_attribute][0]
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except KeyError:
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logger.warning(
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"SAML2 response lacks a '%s' attestation", self._mxid_source_attribute,
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)
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raise SynapseError(
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400, "%s not in SAML2 response" % (self._mxid_source_attribute,)
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)
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# Use the configured mapper for this mxid_source
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base_mxid_localpart = self._mxid_mapper(mxid_source)
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# Append suffix integer if last call to this function failed to produce
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# a usable mxid
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localpart = base_mxid_localpart + (str(failures) if failures else "")
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# Retrieve the display name from the saml response
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# If displayname is None, the mxid_localpart will be used instead
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displayname = saml_response.ava.get("displayName", [None])[0]
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# Retrieve any emails present in the saml response
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emails = saml_response.ava.get("email", [])
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return {
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"mxid_localpart": localpart,
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"displayname": displayname,
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"emails": emails,
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}
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@staticmethod
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def parse_config(config: dict) -> SamlConfig:
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"""Parse the dict provided by the homeserver's config
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Args:
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config: A dictionary containing configuration options for this provider
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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[str], Set[str]]:
|
|
"""Returns the required attributes of a SAML
|
|
|
|
Args:
|
|
config: A SamlConfig object containing configuration params for this provider
|
|
|
|
Returns:
|
|
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", "email"}
|