Support SAML in the user interactive authentication workflow. (#7102)

author: Patrick Cloke <clokep@users.noreply.github.com> 2020-04-01 08:48:00 -0400
committer: GitHub <noreply@github.com> 2020-04-01 08:48:00 -0400
commit: b9930d24a05e47c36845d8607b12a45eea889be0 (patch)
tree: d6411d13b03978cc8b16d4daba04d0016cc0aff0 /synapse/handlers
parent: Allow admins to create aliases when they are not in the room (#7191) (diff)
download: synapse-b9930d24a05e47c36845d8607b12a45eea889be0.tar.xz
2 files changed, 153 insertions, 14 deletions
diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py
index 2ce1425dfa..7c09d15a72 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -53,6 +53,31 @@ from ._base import BaseHandler
 logger = logging.getLogger(__name__)
 
 
+SUCCESS_TEMPLATE = """
+<html>
+<head>
+<title>Success!</title>
+<meta name='viewport' content='width=device-width, initial-scale=1,
+    user-scalable=no, minimum-scale=1.0, maximum-scale=1.0'>
+<link rel="stylesheet" href="/_matrix/static/client/register/style.css">
+<script>
+if (window.onAuthDone) {
+    window.onAuthDone();
+} else if (window.opener && window.opener.postMessage) {
+     window.opener.postMessage("authDone", "*");
+}
+</script>
+</head>
+<body>
+    <div>
+        <p>Thank you</p>
+        <p>You may now close this window and return to the application</p>
+    </div>
+</body>
+</html>
+"""
+
+
 class AuthHandler(BaseHandler):
     SESSION_EXPIRE_MS = 48 * 60 * 60 * 1000
 
@@ -91,6 +116,7 @@ class AuthHandler(BaseHandler):
         self.hs = hs  # FIXME better possibility to access registrationHandler later?
         self.macaroon_gen = hs.get_macaroon_generator()
         self._password_enabled = hs.config.password_enabled
+        self._saml2_enabled = hs.config.saml2_enabled
 
         # we keep this as a list despite the O(N^2) implication so that we can
         # keep PASSWORD first and avoid confusing clients which pick the first
@@ -106,6 +132,13 @@ class AuthHandler(BaseHandler):
                     if t not in login_types:
                         login_types.append(t)
         self._supported_login_types = login_types
+        # Login types and UI Auth types have a heavy overlap, but are not
+        # necessarily identical. Login types have SSO (and other login types)
+        # added in the rest layer, see synapse.rest.client.v1.login.LoginRestServerlet.on_GET.
+        ui_auth_types = login_types.copy()
+        if self._saml2_enabled:
+            ui_auth_types.append(LoginType.SSO)
+        self._supported_ui_auth_types = ui_auth_types
 
         # Ratelimiter for failed auth during UIA. Uses same ratelimit config
         # as per `rc_login.failed_attempts`.
@@ -113,10 +146,21 @@ class AuthHandler(BaseHandler):
 
         self._clock = self.hs.get_clock()
 
-        # Load the SSO redirect confirmation page HTML template
+        # Load the SSO HTML templates.
+
+        # The following template is shown to the user during a client login via SSO,
+        # after the SSO completes and before redirecting them back to their client.
+        # It notifies the user they are about to give access to their matrix account
+        # to the client.
         self._sso_redirect_confirm_template = load_jinja2_templates(
             hs.config.sso_redirect_confirm_template_dir, ["sso_redirect_confirm.html"],
         )[0]
+        # The following template is shown during user interactive authentication
+        # in the fallback auth scenario. It notifies the user that they are
+        # authenticating for an operation to occur on their account.
+        self._sso_auth_confirm_template = load_jinja2_templates(
+            hs.config.sso_redirect_confirm_template_dir, ["sso_auth_confirm.html"],
+        )[0]
 
         self._server_name = hs.config.server_name
 
@@ -130,6 +174,7 @@ class AuthHandler(BaseHandler):
         request: SynapseRequest,
         request_body: Dict[str, Any],
         clientip: str,
+        description: str,
     ):
         """
         Checks that the user is who they claim to be, via a UI auth.
@@ -147,6 +192,9 @@ class AuthHandler(BaseHandler):
 
             clientip: The IP address of the client.
 
+            description: A human readable string to be displayed to the user that
+                         describes the operation happening on their account.
+
         Returns:
             defer.Deferred[dict]: the parameters for this request (which may
                 have been given only in a previous call).
@@ -175,11 +223,11 @@ class AuthHandler(BaseHandler):
         )
 
         # build a list of supported flows
-        flows = [[login_type] for login_type in self._supported_login_types]
+        flows = [[login_type] for login_type in self._supported_ui_auth_types]
 
         try:
             result, params, _ = yield self.check_auth(
-                flows, request, request_body, clientip
+                flows, request, request_body, clientip, description
             )
         except LoginError:
             # Update the ratelimite to say we failed (`can_do_action` doesn't raise).
@@ -193,7 +241,7 @@ class AuthHandler(BaseHandler):
             raise
 
         # find the completed login type
-        for login_type in self._supported_login_types:
+        for login_type in self._supported_ui_auth_types:
             if login_type not in result:
                 continue
 
@@ -224,6 +272,7 @@ class AuthHandler(BaseHandler):
         request: SynapseRequest,
         clientdict: Dict[str, Any],
         clientip: str,
+        description: str,
     ):
         """
         Takes a dictionary sent by the client in the login / registration
@@ -250,6 +299,9 @@ class AuthHandler(BaseHandler):
 
             clientip: The IP address of the client.
 
+            description: A human readable string to be displayed to the user that
+                         describes the operation happening on their account.
+
         Returns:
             defer.Deferred[dict, dict, str]: a deferred tuple of
                 (creds, params, session_id).
@@ -299,12 +351,18 @@ class AuthHandler(BaseHandler):
         comparator = (request.uri, request.method, clientdict)
         if "ui_auth" not in session:
             session["ui_auth"] = comparator
+            self._save_session(session)
         elif session["ui_auth"] != comparator:
             raise SynapseError(
                 403,
                 "Requested operation has changed during the UI authentication session.",
             )
 
+        # Add a human readable description to the session.
+        if "description" not in session:
+            session["description"] = description
+            self._save_session(session)
+
         if not authdict:
             raise InteractiveAuthIncompleteError(
                 self._auth_dict_for_flows(flows, session)
@@ -991,6 +1049,56 @@ class AuthHandler(BaseHandler):
         else:
             return defer.succeed(False)
 
+    def start_sso_ui_auth(self, redirect_url: str, session_id: str) -> str:
+        """
+        Get the HTML for the SSO redirect confirmation page.
+
+        Args:
+            redirect_url: The URL to redirect to the SSO provider.
+            session_id: The user interactive authentication session ID.
+
+        Returns:
+            The HTML to render.
+        """
+        session = self._get_session_info(session_id)
+        # Get the human readable operation of what is occurring, falling back to
+        # a generic message if it isn't available for some reason.
+        description = session.get("description", "modify your account")
+        return self._sso_auth_confirm_template.render(
+            description=description, redirect_url=redirect_url,
+        )
+
+    def complete_sso_ui_auth(
+        self, registered_user_id: str, session_id: str, request: SynapseRequest,
+    ):
+        """Having figured out a mxid for this user, complete the HTTP request
+
+        Args:
+            registered_user_id: The registered user ID to complete SSO login for.
+            request: The request to complete.
+            client_redirect_url: The URL to which to redirect the user at the end of the
+                process.
+        """
+        # Mark the stage of the authentication as successful.
+        sess = self._get_session_info(session_id)
+        if "creds" not in sess:
+            sess["creds"] = {}
+        creds = sess["creds"]
+
+        # Save the user who authenticated with SSO, this will be used to ensure
+        # that the account be modified is also the person who logged in.
+        creds[LoginType.SSO] = registered_user_id
+        self._save_session(sess)
+
+        # Render the HTML and return.
+        html_bytes = SUCCESS_TEMPLATE.encode("utf8")
+        request.setResponseCode(200)
+        request.setHeader(b"Content-Type", b"text/html; charset=utf-8")
+        request.setHeader(b"Content-Length", b"%d" % (len(html_bytes),))
+
+        request.write(html_bytes)
+        finish_request(request)
+
     def complete_sso_login(
         self,
         registered_user_id: str,
diff --git a/synapse/handlers/saml_handler.py b/synapse/handlers/saml_handler.py
index dc04b53f43..4741c82f61 100644
--- a/synapse/handlers/saml_handler.py
+++ b/synapse/handlers/saml_handler.py
@@ -14,7 +14,7 @@
 # limitations under the License.
 import logging
 import re
-from typing import Tuple
+from typing import Optional, Tuple
 
 import attr
 import saml2
@@ -44,11 +44,15 @@ class Saml2SessionData:
 
     # 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:
     def __init__(self, hs):
         self._saml_client = Saml2Client(hs.config.saml2_sp_config)
+        self._auth = hs.get_auth()
         self._auth_handler = hs.get_auth_handler()
         self._registration_handler = hs.get_registration_handler()
 
@@ -77,12 +81,14 @@ class SamlHandler:
 
         self._error_html_content = hs.config.saml2_error_html_content
 
-    def handle_redirect_request(self, client_redirect_url):
+    def handle_redirect_request(self, client_redirect_url, ui_auth_session_id=None):
         """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
+            ui_auth_session_id (Optional[str]): The session ID of the ongoing UI Auth (or
+                None if this is a login).
 
         Returns:
             bytes: URL to redirect to
@@ -92,7 +98,9 @@ class SamlHandler:
         )
 
         now = self._clock.time_msec()
-        self._outstanding_requests_dict[reqid] = Saml2SessionData(creation_time=now)
+        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":
@@ -119,7 +127,9 @@ class SamlHandler:
         self.expire_sessions()
 
         try:
-            user_id = await self._map_saml_response_to_user(resp_bytes, relay_state)
+            user_id, current_session = await self._map_saml_response_to_user(
+                resp_bytes, relay_state
+            )
         except RedirectException:
             # Raise the exception as per the wishes of the SAML module response
             raise
@@ -137,9 +147,28 @@ class SamlHandler:
             finish_request(request)
             return
 
-        self._auth_handler.complete_sso_login(user_id, request, relay_state)
+        # Complete the interactive auth session or the login.
+        if current_session and current_session.ui_auth_session_id:
+            self._auth_handler.complete_sso_ui_auth(
+                user_id, current_session.ui_auth_session_id, request
+            )
+
+        else:
+            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
+    ) -> Tuple[str, Optional[Saml2SessionData]]:
+        """
+        Given a sample response, retrieve the cached session and user for it.
 
-    async def _map_saml_response_to_user(self, resp_bytes, client_redirect_url):
+        Args:
+            resp_bytes: The SAML response.
+            client_redirect_url: The redirect URL passed in by the client.
+
+        Returns:
+             Tuple of the user ID and SAML session associated with this response.
+        """
         try:
             saml2_auth = self._saml_client.parse_authn_request_response(
                 resp_bytes,
@@ -167,7 +196,9 @@ class SamlHandler:
 
         logger.info("SAML2 mapped attributes: %s", saml2_auth.ava)
 
-        self._outstanding_requests_dict.pop(saml2_auth.in_response_to, None)
+        current_session = self._outstanding_requests_dict.pop(
+            saml2_auth.in_response_to, None
+        )
 
         remote_user_id = self._user_mapping_provider.get_remote_user_id(
             saml2_auth, client_redirect_url
@@ -188,7 +219,7 @@ class SamlHandler:
             )
             if registered_user_id is not None:
                 logger.info("Found existing mapping %s", registered_user_id)
-                return registered_user_id
+                return registered_user_id, current_session
 
             # backwards-compatibility hack: see if there is an existing user with a
             # suitable mapping from the uid
@@ -213,7 +244,7 @@ class SamlHandler:
                     await self._datastore.record_user_external_id(
                         self._auth_provider_id, remote_user_id, registered_user_id
                     )
-                    return registered_user_id
+                    return registered_user_id, current_session
 
             # Map saml response to user attributes using the configured mapping provider
             for i in range(1000):
@@ -260,7 +291,7 @@ class SamlHandler:
             await self._datastore.record_user_external_id(
                 self._auth_provider_id, remote_user_id, registered_user_id
             )
-            return registered_user_id
+            return registered_user_id, current_session
 
     def expire_sessions(self):
         expire_before = self._clock.time_msec() - self._saml2_session_lifetime
author	Patrick Cloke <clokep@users.noreply.github.com>	2020-04-01 08:48:00 -0400
committer	GitHub <noreply@github.com>	2020-04-01 08:48:00 -0400
commit	b9930d24a05e47c36845d8607b12a45eea889be0 (patch)
tree	d6411d13b03978cc8b16d4daba04d0016cc0aff0 /synapse/handlers
parent	Allow admins to create aliases when they are not in the room (#7191) (diff)
download	synapse-b9930d24a05e47c36845d8607b12a45eea889be0.tar.xz