diff --git a/synapse/handlers/saml.py b/synapse/handlers/saml.py
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+++ b/synapse/handlers/saml.py
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+# 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 TYPE_CHECKING, Callable, Dict, Optional, Set, 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.handlers._base import BaseHandler
+from synapse.handlers.sso import MappingException, UserAttributes
+from synapse.http.servlet import parse_string
+from synapse.http.site import SynapseRequest
+from synapse.module_api import ModuleApi
+from synapse.types import (
+ UserID,
+ map_username_to_mxid_localpart,
+ mxid_localpart_allowed_characters,
+)
+from synapse.util.iterutils import chunk_seq
+
+if TYPE_CHECKING:
+ from synapse.server import HomeServer
+
+logger = logging.getLogger(__name__)
+
+
+@attr.s(slots=True)
+class Saml2SessionData:
+ """Data we track about SAML2 sessions"""
+
+ # time the session was created, in milliseconds
+ creation_time = attr.ib()
+ # The user interactive authentication session ID associated with this SAML
+ # session (or None if this SAML session is for an initial login).
+ ui_auth_session_id = attr.ib(type=Optional[str], default=None)
+
+
+class SamlHandler(BaseHandler):
+ def __init__(self, hs: "HomeServer"):
+ super().__init__(hs)
+ self._saml_client = Saml2Client(hs.config.saml2_sp_config)
+ self._saml_idp_entityid = hs.config.saml2_idp_entityid
+
+ self._saml2_session_lifetime = hs.config.saml2_session_lifetime
+ self._grandfathered_mxid_source_attribute = (
+ hs.config.saml2_grandfathered_mxid_source_attribute
+ )
+ self._saml2_attribute_requirements = hs.config.saml2.attribute_requirements
+ self._error_template = hs.config.sso_error_template
+
+ # 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.idp_id = "saml"
+
+ # user-facing name of this auth provider
+ self.idp_name = "SAML"
+
+ # we do not currently support icons/brands for SAML auth, but this is required by
+ # the SsoIdentityProvider protocol type.
+ self.idp_icon = None
+ self.idp_brand = None
+ self.unstable_idp_brand = None
+
+ # a map from saml session id to Saml2SessionData object
+ self._outstanding_requests_dict = {} # type: Dict[str, Saml2SessionData]
+
+ self._sso_handler = hs.get_sso_handler()
+ self._sso_handler.register_identity_provider(self)
+
+ async def handle_redirect_request(
+ self,
+ request: SynapseRequest,
+ client_redirect_url: Optional[bytes],
+ ui_auth_session_id: Optional[str] = None,
+ ) -> str:
+ """Handle an incoming request to /login/sso/redirect
+
+ Args:
+ request: the incoming HTTP request
+ client_redirect_url: the URL that we should redirect the
+ client to after login (or None for UI Auth).
+ ui_auth_session_id: The session ID of the ongoing UI Auth (or
+ None if this is a login).
+
+ Returns:
+ URL to redirect to
+ """
+ if not client_redirect_url:
+ # Some SAML identity providers (e.g. Google) require a
+ # RelayState parameter on requests, so pass in a dummy redirect URL
+ # (which will never get used).
+ client_redirect_url = b"unused"
+
+ reqid, info = self._saml_client.prepare_for_authenticate(
+ entityid=self._saml_idp_entityid, relay_state=client_redirect_url
+ )
+
+ # Since SAML sessions timeout it is useful to log when they were created.
+ logger.info("Initiating a new SAML session: %s" % (reqid,))
+
+ now = self.clock.time_msec()
+ self._outstanding_requests_dict[reqid] = Saml2SessionData(
+ creation_time=now,
+ ui_auth_session_id=ui_auth_session_id,
+ )
+
+ 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: SynapseRequest) -> None:
+ """Handle an incoming request to /_synapse/client/saml2/authn_response
+
+ Args:
+ request: the incoming request from the browser. We'll
+ respond to it with a redirect.
+
+ Returns:
+ 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()
+
+ try:
+ saml2_auth = self._saml_client.parse_authn_request_response(
+ resp_bytes,
+ saml2.BINDING_HTTP_POST,
+ outstanding=self._outstanding_requests_dict,
+ )
+ except saml2.response.UnsolicitedResponse as e:
+ # the pysaml2 library helpfully logs an ERROR here, but neglects to log
+ # the session ID. I don't really want to put the full text of the exception
+ # in the (user-visible) exception message, so let's log the exception here
+ # so we can track down the session IDs later.
+ logger.warning(str(e))
+ self._sso_handler.render_error(
+ request, "unsolicited_response", "Unexpected SAML2 login."
+ )
+ return
+ except Exception as e:
+ self._sso_handler.render_error(
+ request,
+ "invalid_response",
+ "Unable to parse SAML2 response: %s." % (e,),
+ )
+ return
+
+ if saml2_auth.not_signed:
+ self._sso_handler.render_error(
+ request, "unsigned_respond", "SAML2 response was not signed."
+ )
+ return
+
+ logger.debug("SAML2 response: %s", saml2_auth.origxml)
+
+ await self._handle_authn_response(request, saml2_auth, relay_state)
+
+ async def _handle_authn_response(
+ self,
+ request: SynapseRequest,
+ saml2_auth: saml2.response.AuthnResponse,
+ relay_state: str,
+ ) -> None:
+ """Handle an AuthnResponse, having parsed it from the request params
+
+ Assumes that the signature on the response object has been checked. Maps
+ the user onto an MXID, registering them if necessary, and returns a response
+ to the browser.
+
+ Args:
+ request: the incoming request from the browser. We'll respond to it with an
+ HTML page or a redirect
+ saml2_auth: the parsed AuthnResponse object
+ relay_state: the RelayState query param, which encodes the URI to rediret
+ back to
+ """
+
+ for assertion in saml2_auth.assertions:
+ # kibana limits the length of a log field, whereas this is all rather
+ # useful, so split it up.
+ count = 0
+ for part in chunk_seq(str(assertion), 10000):
+ logger.info(
+ "SAML2 assertion: %s%s", "(%i)..." % (count,) if count else "", part
+ )
+ count += 1
+
+ logger.info("SAML2 mapped attributes: %s", saml2_auth.ava)
+
+ current_session = self._outstanding_requests_dict.pop(
+ saml2_auth.in_response_to, None
+ )
+
+ # first check if we're doing a UIA
+ if current_session and current_session.ui_auth_session_id:
+ try:
+ remote_user_id = self._remote_id_from_saml_response(saml2_auth, None)
+ except MappingException as e:
+ logger.exception("Failed to extract remote user id from SAML response")
+ self._sso_handler.render_error(request, "mapping_error", str(e))
+ return
+
+ return await self._sso_handler.complete_sso_ui_auth_request(
+ self.idp_id,
+ remote_user_id,
+ current_session.ui_auth_session_id,
+ request,
+ )
+
+ # otherwise, we're handling a login request.
+
+ # Ensure that the attributes of the logged in user meet the required
+ # attributes.
+ if not self._sso_handler.check_required_attributes(
+ request, saml2_auth.ava, self._saml2_attribute_requirements
+ ):
+ return
+
+ # Call the mapper to register/login the user
+ try:
+ await self._complete_saml_login(saml2_auth, request, relay_state)
+ except MappingException as e:
+ logger.exception("Could not map user")
+ self._sso_handler.render_error(request, "mapping_error", str(e))
+
+ async def _complete_saml_login(
+ self,
+ saml2_auth: saml2.response.AuthnResponse,
+ request: SynapseRequest,
+ client_redirect_url: str,
+ ) -> None:
+ """
+ Given a SAML response, complete the login flow
+
+ Retrieves the remote user ID, registers the user if necessary, and serves
+ a redirect back to the client with a login-token.
+
+ Args:
+ saml2_auth: The parsed SAML2 response.
+ request: The request to respond to
+ client_redirect_url: The redirect URL passed in by the client.
+
+ Raises:
+ MappingException if there was a problem mapping the response to a user.
+ RedirectException: some mapping providers may raise this if they need
+ to redirect to an interstitial page.
+ """
+ remote_user_id = self._remote_id_from_saml_response(
+ saml2_auth, client_redirect_url
+ )
+
+ async def saml_response_to_remapped_user_attributes(
+ failures: int,
+ ) -> UserAttributes:
+ """
+ Call the mapping provider to map a SAML response to user attributes and coerce the result into the standard form.
+
+ This is backwards compatibility for abstraction for the SSO handler.
+ """
+ # Call the mapping provider.
+ result = self._user_mapping_provider.saml_response_to_user_attributes(
+ saml2_auth, failures, client_redirect_url
+ )
+ # Remap some of the results.
+ return UserAttributes(
+ localpart=result.get("mxid_localpart"),
+ display_name=result.get("displayname"),
+ emails=result.get("emails", []),
+ )
+
+ async def grandfather_existing_users() -> Optional[str]:
+ # 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.server_name
+ ).to_string()
+
+ logger.debug(
+ "Looking for existing account based on mapped %s %s",
+ self._grandfathered_mxid_source_attribute,
+ user_id,
+ )
+
+ users = await self.store.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)
+ return registered_user_id
+
+ return None
+
+ await self._sso_handler.complete_sso_login_request(
+ self.idp_id,
+ remote_user_id,
+ request,
+ client_redirect_url,
+ saml_response_to_remapped_user_attributes,
+ grandfather_existing_users,
+ )
+
+ def _remote_id_from_saml_response(
+ self,
+ saml2_auth: saml2.response.AuthnResponse,
+ client_redirect_url: Optional[str],
+ ) -> str:
+ """Extract the unique remote id from a SAML2 AuthnResponse
+
+ Args:
+ saml2_auth: The parsed SAML2 response.
+ client_redirect_url: The redirect URL passed in by the client.
+ Returns:
+ remote user id
+
+ Raises:
+ MappingException if there was an error extracting the user id
+ """
+ # It's not obvious why we need to pass in the redirect URI to the mapping
+ # provider, but we do :/
+ remote_user_id = self._user_mapping_provider.get_remote_user_id(
+ saml2_auth, client_redirect_url
+ )
+
+ if not remote_user_id:
+ raise MappingException(
+ "Failed to extract remote user id from SAML response"
+ )
+
+ return remote_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:
+ """Replace any characters which are not allowed in Matrix IDs with a dot."""
+ 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,
+} # type: Dict[str, Callable[[str], str]]
+
+
+@attr.s
+class SamlConfig:
+ mxid_source_attribute = attr.ib()
+ mxid_mapper = attr.ib()
+
+
+class DefaultSamlMappingProvider:
+ __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
+
+ self._grandfathered_mxid_source_attribute = (
+ module_api._hs.config.saml2_grandfathered_mxid_source_attribute
+ )
+
+ def get_remote_user_id(
+ self, saml_response: saml2.response.AuthnResponse, client_redirect_url: str
+ ) -> str:
+ """Extracts the remote user id from the SAML response"""
+ try:
+ return saml_response.ava["uid"][0]
+ except KeyError:
+ logger.warning("SAML2 response lacks a 'uid' attestation")
+ raise MappingException("'uid' not in SAML2 response")
+
+ 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
+ * emails (list[str]): Any emails for 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
+ localpart = self._mxid_mapper(mxid_source)
+
+ # Append suffix integer if last call to this function failed to produce
+ # a usable 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]
+
+ # Retrieve any emails present in the saml response
+ emails = saml_response.ava.get("email", [])
+
+ return {
+ "mxid_localpart": localpart,
+ "displayname": displayname,
+ "emails": emails,
+ }
+
+ @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[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"}
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