diff --git a/synapse/handlers/saml_handler.py b/synapse/handlers/saml_handler.py
index 66b063f991..8715abd4d1 100644
--- a/synapse/handlers/saml_handler.py
+++ b/synapse/handlers/saml_handler.py
@@ -21,9 +21,10 @@ import saml2
import saml2.response
from saml2.client import Saml2Client
-from synapse.api.errors import AuthError, SynapseError
+from synapse.api.errors import SynapseError
from synapse.config import ConfigError
from synapse.config.saml2_config import SamlAttributeRequirement
+from synapse.http.server import respond_with_html
from synapse.http.servlet import parse_string
from synapse.http.site import SynapseRequest
from synapse.module_api import ModuleApi
@@ -41,6 +42,10 @@ if TYPE_CHECKING:
logger = logging.getLogger(__name__)
+class MappingException(Exception):
+ """Used to catch errors when mapping the SAML2 response to a user."""
+
+
@attr.s
class Saml2SessionData:
"""Data we track about SAML2 sessions"""
@@ -68,6 +73,7 @@ class SamlHandler:
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(
@@ -84,6 +90,25 @@ class SamlHandler:
# a lock on the mappings
self._mapping_lock = Linearizer(name="saml_mapping", clock=self._clock)
+ def _render_error(
+ self, request, error: str, error_description: Optional[str] = None
+ ) -> None:
+ """Render the error template and respond to the request with it.
+
+ This is used to show errors to the user. The template of this page can
+ be found under `synapse/res/templates/sso_error.html`.
+
+ Args:
+ request: The incoming request from the browser.
+ We'll respond with an HTML page describing the error.
+ error: A technical identifier for this error.
+ error_description: A human-readable description of the error.
+ """
+ html = self._error_template.render(
+ error=error, error_description=error_description
+ )
+ respond_with_html(request, 400, html)
+
def handle_redirect_request(
self, client_redirect_url: bytes, ui_auth_session_id: Optional[str] = None
) -> bytes:
@@ -134,49 +159,6 @@ class SamlHandler:
# the dict.
self.expire_sessions()
- # Pull out the user-agent and IP from the request.
- user_agent = request.requestHeaders.getRawHeaders(b"User-Agent", default=[b""])[
- 0
- ].decode("ascii", "surrogateescape")
- ip_address = self.hs.get_ip_from_request(request)
-
- user_id, current_session = await self._map_saml_response_to_user(
- resp_bytes, relay_state, user_agent, ip_address
- )
-
- # Complete the interactive auth session or the login.
- if current_session and current_session.ui_auth_session_id:
- await self._auth_handler.complete_sso_ui_auth(
- user_id, current_session.ui_auth_session_id, request
- )
-
- else:
- await self._auth_handler.complete_sso_login(user_id, request, relay_state)
-
- async def _map_saml_response_to_user(
- self,
- resp_bytes: str,
- client_redirect_url: str,
- user_agent: str,
- ip_address: str,
- ) -> Tuple[str, Optional[Saml2SessionData]]:
- """
- Given a sample response, retrieve the cached session and user for it.
-
- Args:
- resp_bytes: The SAML response.
- client_redirect_url: The redirect URL passed in by the client.
- user_agent: The user agent of the client making the request.
- ip_address: The IP address of the client making the request.
-
- Returns:
- Tuple of the user ID and SAML session associated with this response.
-
- Raises:
- SynapseError if there was a problem with the response.
- RedirectException: some mapping providers may raise this if they need
- to redirect to an interstitial page.
- """
try:
saml2_auth = self._saml_client.parse_authn_request_response(
resp_bytes,
@@ -189,12 +171,23 @@ class SamlHandler:
# 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))
- raise SynapseError(400, "Unexpected SAML2 login.")
+ self._render_error(
+ request, "unsolicited_response", "Unexpected SAML2 login."
+ )
+ return
except Exception as e:
- raise SynapseError(400, "Unable to parse SAML2 response: %s." % (e,))
+ self._render_error(
+ request,
+ "invalid_response",
+ "Unable to parse SAML2 response: %s." % (e,),
+ )
+ return
if saml2_auth.not_signed:
- raise SynapseError(400, "SAML2 response was not signed.")
+ self._render_error(
+ request, "unsigned_respond", "SAML2 response was not signed."
+ )
+ return
logger.debug("SAML2 response: %s", saml2_auth.origxml)
for assertion in saml2_auth.assertions:
@@ -213,15 +206,73 @@ class SamlHandler:
saml2_auth.in_response_to, None
)
+ # Ensure that the attributes of the logged in user meet the required
+ # attributes.
for requirement in self._saml2_attribute_requirements:
- _check_attribute_requirement(saml2_auth.ava, requirement)
+ if not _check_attribute_requirement(saml2_auth.ava, requirement):
+ self._render_error(
+ request, "unauthorised", "You are not authorised to log in here."
+ )
+ return
+
+ # Pull out the user-agent and IP from the request.
+ user_agent = request.requestHeaders.getRawHeaders(b"User-Agent", default=[b""])[
+ 0
+ ].decode("ascii", "surrogateescape")
+ ip_address = self.hs.get_ip_from_request(request)
+
+ # Call the mapper to register/login the user
+ try:
+ user_id = await self._map_saml_response_to_user(
+ saml2_auth, relay_state, user_agent, ip_address
+ )
+ except MappingException as e:
+ logger.exception("Could not map user")
+ self._render_error(request, "mapping_error", str(e))
+ return
+
+ # Complete the interactive auth session or the login.
+ if current_session and current_session.ui_auth_session_id:
+ await self._auth_handler.complete_sso_ui_auth(
+ user_id, current_session.ui_auth_session_id, request
+ )
+
+ else:
+ await self._auth_handler.complete_sso_login(user_id, request, relay_state)
+
+ async def _map_saml_response_to_user(
+ self,
+ saml2_auth: saml2.response.AuthnResponse,
+ client_redirect_url: str,
+ user_agent: str,
+ ip_address: str,
+ ) -> str:
+ """
+ Given a SAML response, retrieve the user ID for it and possibly register the user.
+
+ Args:
+ saml2_auth: The parsed SAML2 response.
+ client_redirect_url: The redirect URL passed in by the client.
+ user_agent: The user agent of the client making the request.
+ ip_address: The IP address of the client making the request.
+
+ Returns:
+ The user ID associated with this response.
+
+ 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._user_mapping_provider.get_remote_user_id(
saml2_auth, client_redirect_url
)
if not remote_user_id:
- raise Exception("Failed to extract remote user id from SAML response")
+ raise MappingException(
+ "Failed to extract remote user id from SAML response"
+ )
with (await self._mapping_lock.queue(self._auth_provider_id)):
# first of all, check if we already have a mapping for this user
@@ -235,7 +286,7 @@ class SamlHandler:
)
if registered_user_id is not None:
logger.info("Found existing mapping %s", registered_user_id)
- return registered_user_id, current_session
+ return registered_user_id
# backwards-compatibility hack: see if there is an existing user with a
# suitable mapping from the uid
@@ -260,7 +311,7 @@ class SamlHandler:
await self._datastore.record_user_external_id(
self._auth_provider_id, remote_user_id, registered_user_id
)
- return registered_user_id, current_session
+ return registered_user_id
# Map saml response to user attributes using the configured mapping provider
for i in range(1000):
@@ -277,7 +328,7 @@ class SamlHandler:
localpart = attribute_dict.get("mxid_localpart")
if not localpart:
- raise Exception(
+ raise MappingException(
"Error parsing SAML2 response: SAML mapping provider plugin "
"did not return a mxid_localpart value"
)
@@ -294,8 +345,8 @@ class SamlHandler:
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"
+ raise MappingException(
+ "Unable to generate a Matrix ID from the SAML response"
)
logger.info("Mapped SAML user to local part %s", localpart)
@@ -310,7 +361,7 @@ class SamlHandler:
await self._datastore.record_user_external_id(
self._auth_provider_id, remote_user_id, registered_user_id
)
- return registered_user_id, current_session
+ return registered_user_id
def expire_sessions(self):
expire_before = self._clock.time_msec() - self._saml2_session_lifetime
@@ -323,11 +374,11 @@ class SamlHandler:
del self._outstanding_requests_dict[reqid]
-def _check_attribute_requirement(ava: dict, req: SamlAttributeRequirement):
+def _check_attribute_requirement(ava: dict, req: SamlAttributeRequirement) -> bool:
values = ava.get(req.attribute, [])
for v in values:
if v == req.value:
- return
+ return True
logger.info(
"SAML2 attribute %s did not match required value '%s' (was '%s')",
@@ -335,7 +386,7 @@ def _check_attribute_requirement(ava: dict, req: SamlAttributeRequirement):
req.value,
values,
)
- raise AuthError(403, "You are not authorized to log in here.")
+ return False
DOT_REPLACE_PATTERN = re.compile(
@@ -390,7 +441,7 @@ class DefaultSamlMappingProvider:
return saml_response.ava["uid"][0]
except KeyError:
logger.warning("SAML2 response lacks a 'uid' attestation")
- raise SynapseError(400, "'uid' not in SAML2 response")
+ raise MappingException("'uid' not in SAML2 response")
def saml_response_to_user_attributes(
self,
|
