From 6605470bfb8944d369b8fc73195a380b95b6de9d Mon Sep 17 00:00:00 2001 From: Patrick Cloke Date: Mon, 14 Sep 2020 09:05:36 -0400 Subject: [PATCH] Improve SAML error messages (#8248) --- UPGRADE.rst | 14 ++ changelog.d/8248.feature | 1 + docs/sample_config.yaml | 30 +---- synapse/config/saml2_config.py | 34 +---- synapse/handlers/oidc_handler.py | 4 +- synapse/handlers/saml_handler.py | 169 +++++++++++++++--------- synapse/res/templates/saml_error.html | 52 -------- synapse/res/templates/sso_error.html | 43 +++++- synapse/rest/saml2/response_resource.py | 16 +-- 9 files changed, 178 insertions(+), 185 deletions(-) create mode 100644 changelog.d/8248.feature delete mode 100644 synapse/res/templates/saml_error.html diff --git a/UPGRADE.rst b/UPGRADE.rst index fc8982ddf..49e86e628 100644 --- a/UPGRADE.rst +++ b/UPGRADE.rst @@ -114,6 +114,20 @@ request to with the query parameters from the original link, presented as a URL-encoded form. See the file itself for more details. +Updated Single Sign-on HTML Templates +------------------------------------- + +The ``saml_error.html`` template was removed from Synapse and replaced with the +``sso_error.html`` template. If your Synapse is configured to use SAML and a +custom ``sso_redirect_confirm_template_dir`` configuration then any customisations +of the ``saml_error.html`` template will need to be merged into the ``sso_error.html`` +template. These templates are similar, but the parameters are slightly different: + +* The ``msg`` parameter should be renamed to ``error_description``. +* There is no longer a ``code`` parameter for the response code. +* A string ``error`` parameter is available that includes a short hint of why a + user is seeing the error page. + Upgrading to v1.18.0 ==================== diff --git a/changelog.d/8248.feature b/changelog.d/8248.feature new file mode 100644 index 000000000..f3c4a74bc --- /dev/null +++ b/changelog.d/8248.feature @@ -0,0 +1 @@ +Consolidate the SSO error template across all configuration. diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml index 2a5b2e093..fb04ff283 100644 --- a/docs/sample_config.yaml +++ b/docs/sample_config.yaml @@ -1485,11 +1485,14 @@ trusted_key_servers: # At least one of `sp_config` or `config_path` must be set in this section to # enable SAML login. # -# (You will probably also want to set the following options to `false` to +# You will probably also want to set the following options to `false` to # disable the regular login/registration flows: # * enable_registration # * password_config.enabled # +# You will also want to investigate the settings under the "sso" configuration +# section below. +# # Once SAML support is enabled, a metadata file will be exposed at # https://:/_matrix/saml2/metadata.xml, which you may be able to # use to configure your SAML IdP with. Alternatively, you can manually configure @@ -1612,31 +1615,6 @@ saml2_config: # - attribute: department # value: "sales" - # Directory in which Synapse will try to find the template files below. - # If not set, default templates from within the Synapse package will be used. - # - # DO NOT UNCOMMENT THIS SETTING unless you want to customise the templates. - # If you *do* uncomment it, you will need to make sure that all the templates - # below are in the directory. - # - # Synapse will look for the following templates in this directory: - # - # * HTML page to display to users if something goes wrong during the - # authentication process: 'saml_error.html'. - # - # When rendering, this template is given the following variables: - # * code: an HTML error code corresponding to the error that is being - # returned (typically 400 or 500) - # - # * msg: a textual message describing the error. - # - # The variables will automatically be HTML-escaped. - # - # You can see the default templates at: - # https://github.com/matrix-org/synapse/tree/master/synapse/res/templates - # - #template_dir: "res/templates" - # OpenID Connect integration. The following settings can be used to make Synapse # use an OpenID Connect Provider for authentication, instead of its internal diff --git a/synapse/config/saml2_config.py b/synapse/config/saml2_config.py index cc7401888..99aa8b3bf 100644 --- a/synapse/config/saml2_config.py +++ b/synapse/config/saml2_config.py @@ -169,10 +169,6 @@ class SAML2Config(Config): saml2_config.get("saml_session_lifetime", "15m") ) - self.saml2_error_html_template = self.read_templates( - ["saml_error.html"], saml2_config.get("template_dir") - )[0] - def _default_saml_config_dict( self, required_attributes: set, optional_attributes: set ): @@ -225,11 +221,14 @@ class SAML2Config(Config): # At least one of `sp_config` or `config_path` must be set in this section to # enable SAML login. # - # (You will probably also want to set the following options to `false` to + # You will probably also want to set the following options to `false` to # disable the regular login/registration flows: # * enable_registration # * password_config.enabled # + # You will also want to investigate the settings under the "sso" configuration + # section below. + # # Once SAML support is enabled, a metadata file will be exposed at # https://:/_matrix/saml2/metadata.xml, which you may be able to # use to configure your SAML IdP with. Alternatively, you can manually configure @@ -351,31 +350,6 @@ class SAML2Config(Config): # value: "staff" # - attribute: department # value: "sales" - - # Directory in which Synapse will try to find the template files below. - # If not set, default templates from within the Synapse package will be used. - # - # DO NOT UNCOMMENT THIS SETTING unless you want to customise the templates. - # If you *do* uncomment it, you will need to make sure that all the templates - # below are in the directory. - # - # Synapse will look for the following templates in this directory: - # - # * HTML page to display to users if something goes wrong during the - # authentication process: 'saml_error.html'. - # - # When rendering, this template is given the following variables: - # * code: an HTML error code corresponding to the error that is being - # returned (typically 400 or 500) - # - # * msg: a textual message describing the error. - # - # The variables will automatically be HTML-escaped. - # - # You can see the default templates at: - # https://github.com/matrix-org/synapse/tree/master/synapse/res/templates - # - #template_dir: "res/templates" """ % { "config_dir_path": config_dir_path } diff --git a/synapse/handlers/oidc_handler.py b/synapse/handlers/oidc_handler.py index 1b06f3173..4230dbaf9 100644 --- a/synapse/handlers/oidc_handler.py +++ b/synapse/handlers/oidc_handler.py @@ -131,10 +131,10 @@ class OidcHandler: def _render_error( self, request, error: str, error_description: Optional[str] = None ) -> None: - """Renders the error template and respond with it. + """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``. + be found under `synapse/res/templates/sso_error.html`. Args: request: The incoming request from the browser. diff --git a/synapse/handlers/saml_handler.py b/synapse/handlers/saml_handler.py index 66b063f99..8715abd4d 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, diff --git a/synapse/res/templates/saml_error.html b/synapse/res/templates/saml_error.html deleted file mode 100644 index 01cd9bdaf..000000000 --- a/synapse/res/templates/saml_error.html +++ /dev/null @@ -1,52 +0,0 @@ - - - - - SSO login error - - -{# a 403 means we have actively rejected their login #} -{% if code == 403 %} -

You are not allowed to log in here.

-{% else %} -

- There was an error during authentication: -

-
{{ msg }}
-

- If you are seeing this page after clicking a link sent to you via email, make - sure you only click the confirmation link once, and that you open the - validation link in the same client you're logging in from. -

-

- Try logging in again from your Matrix client and if the problem persists - please contact the server's administrator. -

- - -{% endif %} - - diff --git a/synapse/res/templates/sso_error.html b/synapse/res/templates/sso_error.html index 43a211386..af8459719 100644 --- a/synapse/res/templates/sso_error.html +++ b/synapse/res/templates/sso_error.html @@ -5,14 +5,49 @@ SSO error -

Oops! Something went wrong during authentication.

+{# If an error of unauthorised is returned it means we have actively rejected their login #} +{% if error == "unauthorised" %} +

You are not allowed to log in here.

+{% else %} +

+ There was an error during authentication: +

+
{{ error_description }}
+

+ If you are seeing this page after clicking a link sent to you via email, make + sure you only click the confirmation link once, and that you open the + validation link in the same client you're logging in from. +

Try logging in again from your Matrix client and if the problem persists please contact the server's administrator.

Error: {{ error }}

- {% if error_description %} - 
{{ error_description }}
- {% endif %} + + +{% endif %} diff --git a/synapse/rest/saml2/response_resource.py b/synapse/rest/saml2/response_resource.py index c10188a5d..f6668fb5e 100644 --- a/synapse/rest/saml2/response_resource.py +++ b/synapse/rest/saml2/response_resource.py @@ -13,10 +13,8 @@ # 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. -from twisted.python import failure -from synapse.api.errors import SynapseError -from synapse.http.server import DirectServeHtmlResource, return_html_error +from synapse.http.server import DirectServeHtmlResource class SAML2ResponseResource(DirectServeHtmlResource): @@ -27,21 +25,15 @@ class SAML2ResponseResource(DirectServeHtmlResource): def __init__(self, hs): super().__init__() self._saml_handler = hs.get_saml_handler() - self._error_html_template = hs.config.saml2.saml2_error_html_template async def _async_render_GET(self, request): # We're not expecting any GET request on that resource if everything goes right, # but some IdPs sometimes end up responding with a 302 redirect on this endpoint. # In this case, just tell the user that something went wrong and they should # try to authenticate again. - f = failure.Failure( - SynapseError(400, "Unexpected GET request on /saml2/authn_response") + self._saml_handler._render_error( + request, "unexpected_get", "Unexpected GET request on /saml2/authn_response" ) - return_html_error(f, request, self._error_html_template) async def _async_render_POST(self, request): - try: - await self._saml_handler.handle_saml_response(request) - except Exception: - f = failure.Failure() - return_html_error(f, request, self._error_html_template) + await self._saml_handler.handle_saml_response(request)