Send password reset from HS: Sending the email (#5345)

* Ability to send password reset emails

This changes the default behaviour of Synapse to send password reset
emails itself rather than through an identity server. The reasoning
behind the change is to prevent a malicious identity server from
being able to initiate a password reset attempt and then answering
it, successfully resetting their password, all without the user's
knowledge. This also aides in decentralisation by putting less
trust on the identity server itself, which traditionally is quite
centralised.

If users wish to continue with the old behaviour of proxying
password reset requests through the user's configured identity
server, they can do so by setting
email.enable_password_reset_from_is to True in Synapse's config.

Users should be able that with that option disabled (the default),
password resets will now no longer work unless email sending has
been enabled and set up correctly.

* Fix validation token lifetime email_ prefix

* Add changelog

* Update manifest to include txt/html template files

* Update db

* mark jinja2 and bleach as required dependencies

* Add email settings to default unit test config

* Update unit test template dir

* gen sample config

* Add html5lib as a required dep

* Modify check for smtp settings to be kinder to CI

* silly linting rules

* Correct html5lib dep version number

* one more time

* Change template_dir to originate from synapse root dir

* Revert "Modify check for smtp settings to be kinder to CI"

This reverts commit 6d2d3c9fd3.

* Move templates. New option to disable password resets

* Update templates and make password reset option work

* Change jinja2 and bleach back to opt deps

* Update email condition requirement

* Only import jinja2/bleach if we need it

* Update sample config

* Revert manifest changes for new res directory

* Remove public_baseurl from unittest config

* infer ability to reset password from email config

* Address review comments

* regen sample config

* test for ci

* Remove CI test

* fix bug?

* Run bg update on the master process

changelog.d/5345.feature

@@ -0,0 +1 @@
+Add ability to perform password reset via email without trusting the identity server.

docs/sample_config.yaml

@@ -1018,33 +1018,67 @@ password_config:
 
 
 
-# Enable sending emails for notification events or expiry notices
+# Enable sending emails for password resets, notification events or
-# Defining a custom URL for Riot is only needed if email notifications
+# account expiry notices.
-# should contain links to a self-hosted installation of Riot; when set
-# the "app_name" setting is ignored.
 #
 # If your SMTP server requires authentication, the optional smtp_user &
 # smtp_pass variables should be used
 #
 #email:
-#   enable_notifs: false
+#   enable_notifs: False
 #   smtp_host: "localhost"
-#   smtp_port: 25
+#   smtp_port: 25 # SSL: 465, STARTTLS: 587
 #   smtp_user: "exampleusername"
 #   smtp_pass: "examplepassword"
 #   require_transport_security: False
 #   notif_from: "Your Friendly %(app)s Home Server <noreply@example.com>"
 #   app_name: Matrix
-#   # if template_dir is unset, uses the example templates that are part of
+#
-#   # the Synapse distribution.
+#   # Enable email notifications by default
+#   notif_for_new_users: True
+#
+#   # Defining a custom URL for Riot is only needed if email notifications
+#   # should contain links to a self-hosted installation of Riot; when set
+#   # the "app_name" setting is ignored
+#   riot_base_url: "http://localhost/riot"
+#
+#   # Enable sending password reset emails via the configured, trusted
+#   # identity servers
+#   #
+#   # IMPORTANT! This will give a malicious or overtaken identity server
+#   # the ability to reset passwords for your users! Make absolutely sure
+#   # that you want to do this! It is strongly recommended that password
+#   # reset emails be sent by the homeserver instead
+#   #
+#   # If this option is set to false and SMTP options have not been
+#   # configured, resetting user passwords via email will be disabled
+#   #trust_identity_server_for_password_resets: false
+#
+#   # Configure the time that a validation email or text message code
+#   # will expire after sending
+#   #
+#   # This is currently used for password resets
+#   #validation_token_lifetime: 1h
+#
+#   # Template directory. All template files should be stored within this
+#   # directory
+#   #
 #   #template_dir: res/templates
+#
+#   # Templates for email notifications
+#   #
 #   notif_template_html: notif_mail.html
 #   notif_template_text: notif_mail.txt
-#   # Templates for account expiry notices.
+#
+#   # Templates for account expiry notices
+#   #
 #   expiry_template_html: notice_expiry.html
 #   expiry_template_text: notice_expiry.txt
-#   notif_for_new_users: True
+#
-#   riot_base_url: "http://localhost/riot"
+#   # Templates for password reset emails sent by the homeserver
+#   #
+#   #password_reset_template_html: password_reset.html
+#   #password_reset_template_text: password_reset.txt
 
 
 #password_providers:

synapse/config/emailconfig.py

@@ -50,6 +50,11 @@ class EmailConfig(Config):
         else:
             self.email_app_name = "Matrix"
 
+        # TODO: Rename notif_from to something more generic, or have a separate
+        # from for password resets, message notifications, etc?
+        # Currently the email section is a bit bogged down with settings for
+        # multiple functions. Would be good to split it out into separate
+        # sections and only put the common ones under email:
         self.email_notif_from = email_config.get("notif_from", None)
         if self.email_notif_from is not None:
             # make sure it's valid
@@ -74,7 +79,28 @@ class EmailConfig(Config):
             "account_validity", {},
         ).get("renew_at")
 
-        if self.email_enable_notifs or account_validity_renewal_enabled:
+        email_trust_identity_server_for_password_resets = email_config.get(
+            "trust_identity_server_for_password_resets", False,
+        )
+        self.email_password_reset_behaviour = (
+            "remote" if email_trust_identity_server_for_password_resets else "local"
+        )
+        if self.email_password_reset_behaviour == "local" and email_config == {}:
+            logger.warn(
+                "User password resets have been disabled due to lack of email config"
+            )
+            self.email_password_reset_behaviour = "off"
+
+        # Get lifetime of a validation token in milliseconds
+        self.email_validation_token_lifetime = self.parse_duration(
+            email_config.get("validation_token_lifetime", "1h")
+        )
+
+        if (
+            self.email_enable_notifs
+            or account_validity_renewal_enabled
+            or self.email_password_reset_behaviour == "local"
+        ):
             # make sure we can import the required deps
             import jinja2
             import bleach
@@ -82,6 +108,47 @@ class EmailConfig(Config):
             jinja2
             bleach
 
+        if self.email_password_reset_behaviour == "local":
+            required = [
+                "smtp_host",
+                "smtp_port",
+                "notif_from",
+            ]
+
+            missing = []
+            for k in required:
+                if k not in email_config:
+                    missing.append(k)
+
+            if (len(missing) > 0):
+                raise RuntimeError(
+                    "email.password_reset_behaviour is set to 'local' "
+                    "but required keys are missing: %s" %
+                    (", ".join(["email." + k for k in missing]),)
+                )
+
+            # Templates for password reset emails
+            self.email_password_reset_template_html = email_config.get(
+                "password_reset_template_html", "password_reset.html",
+            )
+            self.email_password_reset_template_text = email_config.get(
+                "password_reset_template_text", "password_reset.txt",
+            )
+
+            # Check templates exist
+            for f in [self.email_password_reset_template_html,
+                      self.email_password_reset_template_text]:
+                p = os.path.join(self.email_template_dir, f)
+                if not os.path.isfile(p):
+                    raise ConfigError("Unable to find template file %s" % (p, ))
+
+            if config.get("public_baseurl") is None:
+                raise RuntimeError(
+                    "email.password_reset_behaviour is set to 'local' but no "
+                    "public_baseurl is set. This is necessary to generate password "
+                    "reset links"
+                )
+
         if self.email_enable_notifs:
             required = [
                 "smtp_host",
@@ -141,31 +208,65 @@ class EmailConfig(Config):
 
     def default_config(self, config_dir_path, server_name, **kwargs):
         return """
-        # Enable sending emails for notification events or expiry notices
+        # Enable sending emails for password resets, notification events or
-        # Defining a custom URL for Riot is only needed if email notifications
+        # account expiry notices.
-        # should contain links to a self-hosted installation of Riot; when set
-        # the "app_name" setting is ignored.
         #
         # If your SMTP server requires authentication, the optional smtp_user &
         # smtp_pass variables should be used
         #
         #email:
-        #   enable_notifs: false
+        #   enable_notifs: False
         #   smtp_host: "localhost"
-        #   smtp_port: 25
+        #   smtp_port: 25 # SSL: 465, STARTTLS: 587
         #   smtp_user: "exampleusername"
         #   smtp_pass: "examplepassword"
         #   require_transport_security: False
         #   notif_from: "Your Friendly %(app)s Home Server <noreply@example.com>"
         #   app_name: Matrix
-        #   # if template_dir is unset, uses the example templates that are part of
+        #
-        #   # the Synapse distribution.
+        #   # Enable email notifications by default
+        #   notif_for_new_users: True
+        #
+        #   # Defining a custom URL for Riot is only needed if email notifications
+        #   # should contain links to a self-hosted installation of Riot; when set
+        #   # the "app_name" setting is ignored
+        #   riot_base_url: "http://localhost/riot"
+        #
+        #   # Enable sending password reset emails via the configured, trusted
+        #   # identity servers
+        #   #
+        #   # IMPORTANT! This will give a malicious or overtaken identity server
+        #   # the ability to reset passwords for your users! Make absolutely sure
+        #   # that you want to do this! It is strongly recommended that password
+        #   # reset emails be sent by the homeserver instead
+        #   #
+        #   # If this option is set to false and SMTP options have not been
+        #   # configured, resetting user passwords via email will be disabled
+        #   #trust_identity_server_for_password_resets: false
+        #
+        #   # Configure the time that a validation email or text message code
+        #   # will expire after sending
+        #   #
+        #   # This is currently used for password resets
+        #   #validation_token_lifetime: 1h
+        #
+        #   # Template directory. All template files should be stored within this
+        #   # directory
+        #   #
         #   #template_dir: res/templates
+        #
+        #   # Templates for email notifications
+        #   #
         #   notif_template_html: notif_mail.html
         #   notif_template_text: notif_mail.txt
-        #   # Templates for account expiry notices.
+        #
+        #   # Templates for account expiry notices
+        #   #
         #   expiry_template_html: notice_expiry.html
         #   expiry_template_text: notice_expiry.txt
-        #   notif_for_new_users: True
+        #
-        #   riot_base_url: "http://localhost/riot"
+        #   # Templates for password reset emails sent by the homeserver
+        #   #
+        #   #password_reset_template_html: password_reset.html
+        #   #password_reset_template_text: password_reset.txt
         """

synapse/config/tls.py

@@ -107,7 +107,7 @@ class TlsConfig(Config):
             certs = []
             for ca_file in custom_ca_list:
                 logger.debug("Reading custom CA certificate file: %s", ca_file)
-                content = self.read_file(ca_file)
+                content = self.read_file(ca_file, "federation_custom_ca_list")
 
                 # Parse the CA certificates
                 try:

synapse/handlers/identity.py

@@ -247,7 +247,14 @@ class IdentityHandler(BaseHandler):
         defer.returnValue(changed)
 
     @defer.inlineCallbacks
-    def requestEmailToken(self, id_server, email, client_secret, send_attempt, **kwargs):
+    def requestEmailToken(
+        self,
+        id_server,
+        email,
+        client_secret,
+        send_attempt,
+        next_link=None,
+    ):
         if not self._should_trust_id_server(id_server):
             raise SynapseError(
                 400, "Untrusted ID server '%s'" % id_server,
@@ -259,7 +266,9 @@ class IdentityHandler(BaseHandler):
             'client_secret': client_secret,
             'send_attempt': send_attempt,
         }
-        params.update(kwargs)
+
+        if next_link:
+            params.update({'next_link': next_link})
 
         try:
             data = yield self.http_client.post_json_get_json(

synapse/push/mailer.py

@@ -80,10 +80,10 @@ ALLOWED_ATTRS = {
 
 
 class Mailer(object):
-    def __init__(self, hs, app_name, notif_template_html, notif_template_text):
+    def __init__(self, hs, app_name, template_html, template_text):
         self.hs = hs
-        self.notif_template_html = notif_template_html
+        self.template_html = template_html
-        self.notif_template_text = notif_template_text
+        self.template_text = template_text
 
         self.sendmail = self.hs.get_sendmail()
         self.store = self.hs.get_datastore()
@@ -93,22 +93,49 @@ class Mailer(object):
 
         logger.info("Created Mailer for app_name %s" % app_name)
 
+    @defer.inlineCallbacks
+    def send_password_reset_mail(
+        self,
+        email_address,
+        token,
+        client_secret,
+        sid,
+    ):
+        """Send an email with a password reset link to a user
+
+        Args:
+            email_address (str): Email address we're sending the password
+                reset to
+            token (str): Unique token generated by the server to verify
+                password reset email was received
+            client_secret (str): Unique token generated by the client to
+                group together multiple email sending attempts
+            sid (str): The generated session ID
+        """
+        if email.utils.parseaddr(email_address)[1] == '':
+            raise RuntimeError("Invalid 'to' email address")
+
+        link = (
+            self.hs.config.public_baseurl +
+            "_synapse/password_reset/email/submit_token"
+            "?token=%s&client_secret=%s&sid=%s" %
+            (token, client_secret, sid)
+        )
+
+        template_vars = {
+            "link": link,
+        }
+
+        yield self.send_email(
+            email_address,
+            "[%s] Password Reset Email" % self.hs.config.server_name,
+            template_vars,
+        )
+
     @defer.inlineCallbacks
     def send_notification_mail(self, app_id, user_id, email_address,
                                push_actions, reason):
-        try:
+        """Send email regarding a user's room notifications"""
-            from_string = self.hs.config.email_notif_from % {
-                "app": self.app_name
-            }
-        except TypeError:
-            from_string = self.hs.config.email_notif_from
-
-        raw_from = email.utils.parseaddr(from_string)[1]
-        raw_to = email.utils.parseaddr(email_address)[1]
-
-        if raw_to == '':
-            raise RuntimeError("Invalid 'to' address")
-
         rooms_in_order = deduped_ordered_list(
             [pa['room_id'] for pa in push_actions]
         )
@@ -176,14 +203,36 @@ class Mailer(object):
             "reason": reason,
         }
 
-        html_text = self.notif_template_html.render(**template_vars)
+        yield self.send_email(
+            email_address,
+            "[%s] %s" % (self.app_name, summary_text),
+            template_vars,
+        )
+
+    @defer.inlineCallbacks
+    def send_email(self, email_address, subject, template_vars):
+        """Send an email with the given information and template text"""
+        try:
+            from_string = self.hs.config.email_notif_from % {
+                "app": self.app_name
+            }
+        except TypeError:
+            from_string = self.hs.config.email_notif_from
+
+        raw_from = email.utils.parseaddr(from_string)[1]
+        raw_to = email.utils.parseaddr(email_address)[1]
+
+        if raw_to == '':
+            raise RuntimeError("Invalid 'to' address")
+
+        html_text = self.template_html.render(**template_vars)
         html_part = MIMEText(html_text, "html", "utf8")
 
-        plain_text = self.notif_template_text.render(**template_vars)
+        plain_text = self.template_text.render(**template_vars)
         text_part = MIMEText(plain_text, "plain", "utf8")
 
         multipart_msg = MIMEMultipart('alternative')
-        multipart_msg['Subject'] = "[%s] %s" % (self.app_name, summary_text)
+        multipart_msg['Subject'] = subject
         multipart_msg['From'] = from_string
         multipart_msg['To'] = email_address
         multipart_msg['Date'] = email.utils.formatdate()

synapse/push/pusher.py

@@ -70,8 +70,8 @@ class PusherFactory(object):
             mailer = Mailer(
                 hs=self.hs,
                 app_name=app_name,
-                notif_template_html=self.notif_template_html,
+                template_html=self.notif_template_html,
-                notif_template_text=self.notif_template_text,
+                template_text=self.notif_template_text,
             )
             self.mailers[app_name] = mailer
         return EmailPusher(self.hs, pusherdict, mailer)

synapse/python_dependencies.py

@@ -77,7 +77,7 @@ REQUIREMENTS = [
 ]
 
 CONDITIONAL_REQUIREMENTS = {
-    "email.enable_notifs": ["Jinja2>=2.9", "bleach>=1.4.2"],
+    "email": ["Jinja2>=2.9", "bleach>=1.4.2"],
     "matrix-synapse-ldap3": ["matrix-synapse-ldap3>=0.1"],
 
     # we use execute_batch, which arrived in psycopg 2.7.

synapse/res/templates/password_reset.html

@@ -0,0 +1,9 @@
+<html>
+<body>
+    <p>A password reset request has been received for your Matrix account. If this was you, please click the link below to confirm resetting your password:</p>
+
+    <a href="{{ link }}">{{ link }}</a>
+
+    <p>If this was not you, please disregard this email and contact your server administrator. Thank you.</p>
+</body>
+</html>

synapse/res/templates/password_reset.txt

@@ -0,0 +1,7 @@
+A password reset request has been received for your Matrix account. If this
+was you, please click the link below to confirm resetting your password:
+
+{{ link }}
+
+If this was not you, please disregard this email and contact your server
+administrator. Thank you.

synapse/rest/client/v2_alpha/account.py

@@ -28,6 +28,7 @@ from synapse.http.servlet import (
     parse_json_object_from_request,
 )
 from synapse.util.msisdn import phone_number_to_msisdn
+from synapse.util.stringutils import random_string
 from synapse.util.threepids import check_3pid_allowed
 
 from ._base import client_patterns, interactive_auth_handler
@@ -41,17 +42,42 @@ class EmailPasswordRequestTokenRestServlet(RestServlet):
     def __init__(self, hs):
         super(EmailPasswordRequestTokenRestServlet, self).__init__()
         self.hs = hs
+        self.datastore = hs.get_datastore()
+        self.config = hs.config
         self.identity_handler = hs.get_handlers().identity_handler
 
+        if self.config.email_password_reset_behaviour == "local":
+            from synapse.push.mailer import Mailer, load_jinja2_templates
+            templates = load_jinja2_templates(
+                config=hs.config,
+                template_html_name=hs.config.email_password_reset_template_html,
+                template_text_name=hs.config.email_password_reset_template_text,
+            )
+            self.mailer = Mailer(
+                hs=self.hs,
+                app_name=self.config.email_app_name,
+                template_html=templates[0],
+                template_text=templates[1],
+            )
+
     @defer.inlineCallbacks
     def on_POST(self, request):
+        if self.config.email_password_reset_behaviour == "off":
+            raise SynapseError(400, "Password resets have been disabled on this server")
+
         body = parse_json_object_from_request(request)
 
         assert_params_in_dict(body, [
-            'id_server', 'client_secret', 'email', 'send_attempt'
+            'client_secret', 'email', 'send_attempt'
         ])
 
-        if not check_3pid_allowed(self.hs, "email", body['email']):
+        # Extract params from body
+        client_secret = body["client_secret"]
+        email = body["email"]
+        send_attempt = body["send_attempt"]
+        next_link = body.get("next_link")  # Optional param
+
+        if not check_3pid_allowed(self.hs, "email", email):
             raise SynapseError(
                 403,
                 "Your email domain is not authorized on this server",
@@ -59,15 +85,100 @@ class EmailPasswordRequestTokenRestServlet(RestServlet):
             )
 
         existingUid = yield self.hs.get_datastore().get_user_id_by_threepid(
-            'email', body['email']
+            'email', email,
         )
 
         if existingUid is None:
             raise SynapseError(400, "Email not found", Codes.THREEPID_NOT_FOUND)
 
-        ret = yield self.identity_handler.requestEmailToken(**body)
+        if self.config.email_password_reset_behaviour == "remote":
+            if 'id_server' not in body:
+                raise SynapseError(400, "Missing 'id_server' param in body")
+
+            # Have the identity server handle the password reset flow
+            ret = yield self.identity_handler.requestEmailToken(
+                body["id_server"], email, client_secret, send_attempt, next_link,
+            )
+        else:
+            # Send password reset emails from Synapse
+            sid = yield self.send_password_reset(
+                email, client_secret, send_attempt, next_link,
+            )
+
+            # Wrap the session id in a JSON object
+            ret = {"sid": sid}
+
         defer.returnValue((200, ret))
 
+    @defer.inlineCallbacks
+    def send_password_reset(
+        self,
+        email,
+        client_secret,
+        send_attempt,
+        next_link=None,
+    ):
+        """Send a password reset email
+
+        Args:
+            email (str): The user's email address
+            client_secret (str): The provided client secret
+            send_attempt (int): Which send attempt this is
+
+        Returns:
+            The new session_id upon success
+
+        Raises:
+            SynapseError is an error occurred when sending the email
+        """
+        # Check that this email/client_secret/send_attempt combo is new or
+        # greater than what we've seen previously
+        session = yield self.datastore.get_threepid_validation_session(
+            "email", client_secret, address=email, validated=False,
+        )
+
+        # Check to see if a session already exists and that it is not yet
+        # marked as validated
+        if session and session.get("validated_at") is None:
+            session_id = session['session_id']
+            last_send_attempt = session['last_send_attempt']
+
+            # Check that the send_attempt is higher than previous attempts
+            if send_attempt <= last_send_attempt:
+                # If not, just return a success without sending an email
+                defer.returnValue(session_id)
+        else:
+            # An non-validated session does not exist yet.
+            # Generate a session id
+            session_id = random_string(16)
+
+        # Generate a new validation token
+        token = random_string(32)
+
+        # Send the mail with the link containing the token, client_secret
+        # and session_id
+        try:
+            yield self.mailer.send_password_reset_mail(
+                email, token, client_secret, session_id,
+            )
+        except Exception:
+            logger.exception(
+                "Error sending a password reset email to %s", email,
+            )
+            raise SynapseError(
+                500, "An error was encountered when sending the password reset email"
+            )
+
+        token_expires = (self.hs.clock.time_msec() +
+                         self.config.email_validation_token_lifetime)
+
+        yield self.datastore.start_or_continue_validation_session(
+            "email", email, session_id, client_secret, send_attempt,
+            next_link, token, token_expires,
+        )
+
+        defer.returnValue(session_id)
+
 
 class MsisdnPasswordRequestTokenRestServlet(RestServlet):
     PATTERNS = client_patterns("/account/password/msisdn/requestToken$")
@@ -80,6 +191,9 @@ class MsisdnPasswordRequestTokenRestServlet(RestServlet):
 
     @defer.inlineCallbacks
     def on_POST(self, request):
+        if not self.config.email_password_reset_behaviour == "off":
+            raise SynapseError(400, "Password resets have been disabled on this server")
+
         body = parse_json_object_from_request(request)
 
         assert_params_in_dict(body, [
@@ -144,6 +258,7 @@ class PasswordRestServlet(RestServlet):
             result, params, _ = yield self.auth_handler.check_auth(
                 [[LoginType.EMAIL_IDENTITY], [LoginType.MSISDN]],
                 body, self.hs.get_ip_from_request(request),
+                password_servlet=True,
             )
 
             if LoginType.EMAIL_IDENTITY in result:

synapse/storage/_base.py

@@ -588,6 +588,10 @@ class SQLBaseStore(object):
         Args:
             table : string giving the table name
             values : dict of new column names and values for them
+            or_ignore : bool stating whether an exception should be raised
+                when a conflicting row already exists. If True, False will be
+                returned by the function instead
+            desc : string giving a description of the transaction
 
         Returns:
             bool: Whether the row was inserted or not. Only useful when
@@ -1228,8 +1232,8 @@ class SQLBaseStore(object):
         )
 
         txn.execute(select_sql, list(keyvalues.values()))
-
         row = txn.fetchone()
+
         if not row:
             if allow_none:
                 return None

synapse/storage/registration.py

@@ -29,6 +29,8 @@ from synapse.storage._base import SQLBaseStore
 from synapse.types import UserID
 from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
 
+THIRTY_MINUTES_IN_MS = 30 * 60 * 1000
+
 
 class RegistrationWorkerStore(SQLBaseStore):
     def __init__(self, db_conn, hs):
@@ -596,6 +598,11 @@ class RegistrationStore(
             "user_threepids_grandfather", self._bg_user_threepids_grandfather,
         )
 
+        # Create a background job for culling expired 3PID validity tokens
+        hs.get_clock().looping_call(
+            self.cull_expired_threepid_validation_tokens, THIRTY_MINUTES_IN_MS,
+        )
+
     @defer.inlineCallbacks
     def add_access_token_to_user(self, user_id, token, device_id=None):
         """Adds an access token for the given user.
@@ -1136,15 +1143,15 @@ class RegistrationStore(
         validated_at=None,
     ):
         """Upsert a threepid validation session
-
         Args:
             medium (str): The medium of the 3PID
             address (str): The address of the 3PID
             client_secret (str): A unique string provided by the client to
                 help identify this validation attempt
+            send_attempt (int): The latest send_attempt on this session
             session_id (str): The id of this validation session
-            validated_at (int): The unix timestamp in milliseconds of when
+            validated_at (int|None): The unix timestamp in milliseconds of
-                the session was marked as valid
+                when the session was marked as valid
         """
         insertion_values = {
             "medium": medium,
@@ -1163,12 +1170,70 @@ class RegistrationStore(
             desc="upsert_threepid_validation_session",
         )
 
+    def start_or_continue_validation_session(
+        self,
+        medium,
+        address,
+        session_id,
+        client_secret,
+        send_attempt,
+        next_link,
+        token,
+        token_expires,
+    ):
+        """Creates a new threepid validation session if it does not already
+        exist and associates a new validation token with it
+
+        Args:
+            medium (str): The medium of the 3PID
+            address (str): The address of the 3PID
+            session_id (str): The id of this validation session
+            client_secret (str): A unique string provided by the client to
+                help identify this validation attempt
+            send_attempt (int): The latest send_attempt on this session
+            next_link (str|None): The link to redirect the user to upon
+                successful validation
+            token (str): The validation token
+            token_expires (int): The timestamp for which after the token
+                will no longer be valid
+        """
+        def start_or_continue_validation_session_txn(txn):
+            # Create or update a validation session
+            self._simple_upsert_txn(
+                txn,
+                table="threepid_validation_session",
+                keyvalues={"session_id": session_id},
+                values={"last_send_attempt": send_attempt},
+                insertion_values={
+                    "medium": medium,
+                    "address": address,
+                    "client_secret": client_secret,
+                },
+            )
+
+            # Create a new validation token with this session ID
+            self._simple_insert_txn(
+                txn,
+                table="threepid_validation_token",
+                values={
+                    "session_id": session_id,
+                    "token": token,
+                    "next_link": next_link,
+                    "expires": token_expires,
+                },
+            )
+
+        return self.runInteraction(
+            "start_or_continue_validation_session",
+            start_or_continue_validation_session_txn,
+        )
+
     def insert_threepid_validation_token(
         self,
         session_id,
         token,
-        next_link,
         expires,
+        next_link=None,
     ):
         """Insert a new 3PID validation token and details
 
@@ -1178,6 +1243,8 @@ class RegistrationStore(
             token (str): The validation token
             expires (int): The timestamp for which after this token will no
                 longer be valid
+            next_link (str|None): The link to redirect the user to upon successful
+                validation
         """
         return self._simple_insert(
             table="threepid_validation_token",

tests/utils.py

@@ -131,7 +131,6 @@ def default_config(name, parse=False):
         "password_providers": [],
         "worker_replication_url": "",
         "worker_app": None,
-        "email_enable_notifs": False,
         "block_non_admin_invites": False,
         "federation_domain_whitelist": None,
         "filter_timeline_limit": 5000,