Collect terms consent from the user during SSO registration

changelog.d/9276.feature

@@ -0,0 +1 @@
+Improve the user experience of setting up an account via single-sign on.

docs/sample_config.yaml

@@ -1998,6 +1998,28 @@ sso:
     #
     #     * username: the localpart of the user's chosen user id
     #
+    # * HTML page allowing the user to consent to the server's terms and
+    #   conditions. This is only shown for new users, and only if
+    #   `user_consent.require_at_registration` is set.
+    #
+    #   When rendering, this template is given the following variables:
+    #
+    #     * server_name: the homeserver's name.
+    #
+    #     * user_id: the user's matrix proposed ID.
+    #
+    #     * user_profile.display_name: the user's proposed display name, if any.
+    #
+    #     * consent_version: the version of the terms that the user will be
+    #       shown
+    #
+    #     * terms_url: a link to the page showing the terms.
+    #
+    #   The template should render a form which submits the following fields:
+    #
+    #     * accepted_version: the version of the terms accepted by the user
+    #       (ie, 'consent_version' from the input variables).
+    #
     # * HTML page for a confirmation step before redirecting back to the client
     #   with the login token: 'sso_redirect_confirm.html'.
     #

docs/workers.md

@@ -259,6 +259,7 @@ using):
     ^/_matrix/client/(api/v1|r0|unstable)/login/sso/redirect
     ^/_synapse/client/pick_idp$
     ^/_synapse/client/pick_username
+    ^/_synapse/client/new_user_consent$
     ^/_synapse/client/sso_register$
 
     # OpenID Connect requests.

synapse/config/sso.py

@@ -153,6 +153,28 @@ def generate_config_section(self, **kwargs):
             #
             #     * username: the localpart of the user's chosen user id
             #
+            # * HTML page allowing the user to consent to the server's terms and
+            #   conditions. This is only shown for new users, and only if
+            #   `user_consent.require_at_registration` is set.
+            #
+            #   When rendering, this template is given the following variables:
+            #
+            #     * server_name: the homeserver's name.
+            #
+            #     * user_id: the user's matrix proposed ID.
+            #
+            #     * user_profile.display_name: the user's proposed display name, if any.
+            #
+            #     * consent_version: the version of the terms that the user will be
+            #       shown
+            #
+            #     * terms_url: a link to the page showing the terms.
+            #
+            #   The template should render a form which submits the following fields:
+            #
+            #     * accepted_version: the version of the terms accepted by the user
+            #       (ie, 'consent_version' from the input variables).
+            #
             # * HTML page for a confirmation step before redirecting back to the client
             #   with the login token: 'sso_redirect_confirm.html'.
             #

synapse/handlers/register.py

@@ -694,6 +694,8 @@ async def post_registration_actions(
             access_token: The access token of the newly logged in device, or
                 None if `inhibit_login` enabled.
         """
+        # TODO: 3pid registration can actually happen on the workers. Consider
+        # refactoring it.
         if self.hs.config.worker_app:
             await self._post_registration_client(
                 user_id=user_id, auth_result=auth_result, access_token=access_token

synapse/handlers/sso.py

@@ -155,6 +155,7 @@ class UsernameMappingSession:
     chosen_localpart = attr.ib(type=Optional[str], default=None)
     use_display_name = attr.ib(type=bool, default=True)
     emails_to_use = attr.ib(type=Collection[str], default=())
+    terms_accepted_version = attr.ib(type=Optional[str], default=None)
 
 
 # the HTTP cookie used to track the mapping session id
@@ -190,6 +191,8 @@ def __init__(self, hs: "HomeServer"):
         # map from idp_id to SsoIdentityProvider
         self._identity_providers = {}  # type: Dict[str, SsoIdentityProvider]
 
+        self._consent_at_registration = hs.config.consent.user_consent_at_registration
+
     def register_identity_provider(self, p: SsoIdentityProvider):
         p_id = p.idp_id
         assert p_id not in self._identity_providers
@@ -761,6 +764,38 @@ async def handle_submit_username_request(
                 )
         session.emails_to_use = filtered_emails
 
+        # we may now need to collect consent from the user, in which case, redirect
+        # to the consent-extraction-unit
+        if self._consent_at_registration:
+            redirect_url = b"/_synapse/client/new_user_consent"
+
+        # otherwise, redirect to the completion page
+        else:
+            redirect_url = b"/_synapse/client/sso_register"
+
+        respond_with_redirect(request, redirect_url)
+
+    async def handle_terms_accepted(
+        self, request: Request, session_id: str, terms_version: str
+    ):
+        """Handle a request to the new-user 'consent' endpoint
+
+        Will serve an HTTP response to the request.
+
+        Args:
+            request: HTTP request
+            session_id: ID of the username mapping session, extracted from a cookie
+            terms_version: the version of the terms which the user viewed and consented
+                to
+        """
+        logger.info(
+            "[session %s] User consented to terms version %s",
+            session_id,
+            terms_version,
+        )
+        session = self.get_mapping_session(session_id)
+        session.terms_accepted_version = terms_version
+
         # we're done; now we can register the user
         respond_with_redirect(request, b"/_synapse/client/sso_register")
 
@@ -816,6 +851,15 @@ async def register_sso_user(self, request: Request, session_id: str) -> None:
             path=b"/",
         )
 
+        auth_result = {}
+        if session.terms_accepted_version:
+            # TODO: make this less awful.
+            auth_result[LoginType.TERMS] = True
+
+        await self._registration_handler.post_registration_actions(
+            user_id, auth_result, access_token=None
+        )
+
         await self._auth_handler.complete_sso_login(
             user_id,
             request,

synapse/res/templates/sso_new_user_consent.html

@@ -0,0 +1,39 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <title>SSO redirect confirmation</title>
+    <meta name="viewport" content="width=device-width, user-scalable=no">
+    <style type="text/css">
+      {% include "sso.css" without context %}
+
+      #consent_form {
+        margin-top: 56px;
+      }
+    </style>
+</head>
+    <body>
+        <header>
+            <h1>Your account is nearly ready</h1>
+            <p>Agree to the terms to create your account.</p>
+        </header>
+        <main>
+            <!-- {% if user_profile.avatar_url and user_profile.display_name %} -->
+            <div class="profile">
+                <img src="{{ user_profile.avatar_url | mxc_to_http(64, 64) }}" class="avatar" />
+                <div class="profile-details">
+                    <div class="display-name">{{ user_profile.display_name }}</div>
+                    <div class="user-id">{{ user_id }}</div>
+                </div>
+            </div>
+            <!-- {% endif %} -->
+            <form method="post" action="{{my_url}}" id="consent_form">
+                <p>
+                    <input id="accepted_version" type="checkbox" name="accepted_version" value="{{ consent_version }}" required>
+                    <label for="accepted_version">I have read and agree to the <a href="{{ terms_url }}" target="_blank">terms and conditions</a>.</label>
+                </p>
+                <input type="submit" class="primary-button" value="Continue"/>
+            </form>
+        </main>
+    </body>
+</html>

synapse/rest/synapse/client/__init__.py

@@ -17,6 +17,7 @@
 
 from twisted.web.resource import Resource
 
+from synapse.rest.synapse.client.new_user_consent import NewUserConsentResource
 from synapse.rest.synapse.client.pick_idp import PickIdpResource
 from synapse.rest.synapse.client.pick_username import pick_username_resource
 from synapse.rest.synapse.client.sso_register import SsoRegisterResource
@@ -39,6 +40,7 @@ def build_synapse_client_resource_tree(hs: "HomeServer") -> Mapping[str, Resourc
         # enabled (they just won't work very well if it's not)
         "/_synapse/client/pick_idp": PickIdpResource(hs),
         "/_synapse/client/pick_username": pick_username_resource(hs),
+        "/_synapse/client/new_user_consent": NewUserConsentResource(hs),
         "/_synapse/client/sso_register": SsoRegisterResource(hs),
     }
 

synapse/rest/synapse/client/new_user_consent.py

@@ -0,0 +1,97 @@
+# -*- coding: utf-8 -*-
+# Copyright 2021 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
+from typing import TYPE_CHECKING
+
+from twisted.web.http import Request
+
+from synapse.api.errors import SynapseError
+from synapse.handlers.sso import get_username_mapping_session_cookie_from_request
+from synapse.http.server import DirectServeHtmlResource, respond_with_html
+from synapse.http.servlet import parse_string
+from synapse.types import UserID
+from synapse.util.templates import build_jinja_env
+
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+
+logger = logging.getLogger(__name__)
+
+
+class NewUserConsentResource(DirectServeHtmlResource):
+    """A resource which collects consent to the server's terms from a new user
+
+    This resource gets mounted at /_synapse/client/new_user_consent, and is shown
+    when we are automatically creating a new user due to an SSO login.
+
+    It shows a template which prompts the user to go and read the Ts and Cs, and click
+    a clickybox if they have done so.
+    """
+
+    def __init__(self, hs: "HomeServer"):
+        super().__init__()
+        self._sso_handler = hs.get_sso_handler()
+        self._server_name = hs.hostname
+        self._consent_version = hs.config.consent.user_consent_version
+
+        def template_search_dirs():
+            if hs.config.sso.sso_template_dir:
+                yield hs.config.sso.sso_template_dir
+            yield hs.config.sso.default_template_dir
+
+        self._jinja_env = build_jinja_env(template_search_dirs(), hs.config)
+
+    async def _async_render_GET(self, request: Request) -> None:
+        try:
+            session_id = get_username_mapping_session_cookie_from_request(request)
+            session = self._sso_handler.get_mapping_session(session_id)
+        except SynapseError as e:
+            logger.warning("Error fetching session: %s", e)
+            self._sso_handler.render_error(request, "bad_session", e.msg, code=e.code)
+            return
+
+        user_id = UserID(session.chosen_localpart, self._server_name)
+        user_profile = {
+            "display_name": session.display_name,
+        }
+
+        template_params = {
+            "user_id": user_id.to_string(),
+            "user_profile": user_profile,
+            "consent_version": self._consent_version,
+            "terms_url": "/_matrix/consent?v=%s" % (self._consent_version,),
+        }
+
+        template = self._jinja_env.get_template("sso_new_user_consent.html")
+        html = template.render(template_params)
+        respond_with_html(request, 200, html)
+
+    async def _async_render_POST(self, request: Request):
+        try:
+            session_id = get_username_mapping_session_cookie_from_request(request)
+        except SynapseError as e:
+            logger.warning("Error fetching session cookie: %s", e)
+            self._sso_handler.render_error(request, "bad_session", e.msg, code=e.code)
+            return
+
+        try:
+            accepted_version = parse_string(request, "accepted_version", required=True)
+        except SynapseError as e:
+            self._sso_handler.render_error(request, "bad_param", e.msg, code=e.code)
+            return
+
+        await self._sso_handler.handle_terms_accepted(
+            request, session_id, accepted_version
+        )