Replace trust_identity_server_for_password_resets with account_threepid_delegate

changelog.d/5876.misc

@@ -0,0 +1 @@
+Replace `trust_identity_server_for_password_resets` config option with `account_threepid_delegate`.

docs/sample_config.yaml

@@ -902,6 +902,20 @@ uploads_path: "DATADIR/uploads"
 #  - matrix.org
 #  - vector.im
 
+# Handle threepid (email/phone etc) registration and password resets
+# through a *trusted* identity server. Note that this allows the configured
+# identity server to reset passwords for accounts.
+#
+# If this option is not defined and SMTP options have not been
+# configured, registration by email and resetting user passwords via
+# email will be disabled
+#
+# Otherwise, to enable set this option to the reachable domain name, including protocol
+# definition, for an identity server
+# (e.g "https://matrix.org", "http://localhost:8090")
+#
+#account_threepid_delegate: ""
+
 # Users who register on this homeserver will automatically be joined
 # to these rooms
 #
@@ -1163,19 +1177,6 @@ password_config:
 #   #
 #   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
 #   #

synapse/config/emailconfig.py

@@ -20,6 +20,7 @@
 # This file can't be called email.py because if it is, we cannot:
 import email.utils
 import os
+from enum import Enum
 
 import pkg_resources
 
@@ -74,19 +75,40 @@ def read_config(self, config, **kwargs):
             "renew_at"
         )
 
-        email_trust_identity_server_for_password_resets = email_config.get(
-            "trust_identity_server_for_password_resets", False
+        self.email_threepid_behaviour = (
+            # Have Synapse handle the email sending if account_threepid_delegate
+            # is not defined
+            ThreepidBehaviour.REMOTE
+            if self.account_threepid_delegate
+            else ThreepidBehaviour.LOCAL
         )
-        self.email_password_reset_behaviour = (
-            "remote" if email_trust_identity_server_for_password_resets else "local"
-        )
-        self.password_resets_were_disabled_due_to_email_config = False
-        if self.email_password_reset_behaviour == "local" and email_config == {}:
+        # Prior to Synapse v1.4.0, there was another option that defined whether Synapse would
+        # use an identity server to password reset tokens on its behalf. We now warn the user
+        # if they have this set and tell them to use the updated option, while using a default
+        # identity server in the process.
+        if config.get("trust_identity_server_for_password_resets", False) is True:
+            # Use the first entry in self.trusted_third_party_id_servers instead
+            if self.trusted_third_party_id_servers:
+                self.account_threepid_delegate = self.trusted_third_party_id_servers[0]
+            else:
+                raise ConfigError(
+                    'The config option "trust_identity_server_for_password_resets" '
+                    'has been replaced by "account_threepid_delegate". Attempted to use an '
+                    'identity server from "trusted_third_party_id_servers" but it is empty. '
+                    "Please consult the sample config at docs/sample_config.yaml for "
+                    "details and update your config file."
+                )
+
+        self.local_threepid_emails_disabled_due_to_config = False
+        if (
+            self.email_threepid_behaviour == ThreepidBehaviour.LOCAL
+            and email_config == {}
+        ):
             # We cannot warn the user this has happened here
             # Instead do so when a user attempts to reset their password
-            self.password_resets_were_disabled_due_to_email_config = True
+            self.local_threepid_emails_disabled_due_to_config = True
 
-            self.email_password_reset_behaviour = "off"
+            self.email_threepid_behaviour = ThreepidBehaviour.OFF
 
         # Get lifetime of a validation token in milliseconds
         self.email_validation_token_lifetime = self.parse_duration(
@@ -96,7 +118,7 @@ def read_config(self, config, **kwargs):
         if (
             self.email_enable_notifs
             or account_validity_renewal_enabled
-            or self.email_password_reset_behaviour == "local"
+            or self.email_threepid_behaviour == ThreepidBehaviour.LOCAL
         ):
             # make sure we can import the required deps
             import jinja2
@@ -106,7 +128,7 @@ def read_config(self, config, **kwargs):
             jinja2
             bleach
 
-        if self.email_password_reset_behaviour == "local":
+        if self.email_threepid_behaviour == ThreepidBehaviour.LOCAL:
             required = ["smtp_host", "smtp_port", "notif_from"]
 
             missing = []
@@ -239,19 +261,6 @@ def generate_config_section(self, config_dir_path, server_name, **kwargs):
         #   #
         #   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
         #   #
@@ -289,3 +298,18 @@ def generate_config_section(self, config_dir_path, server_name, **kwargs):
         #   #password_reset_template_success_html: password_reset_success.html
         #   #password_reset_template_failure_html: password_reset_failure.html
         """
+
+
+class ThreepidBehaviour(Enum):
+    """
+    Enum to define the behaviour of Synapse with regards to when it contacts an identity
+    server for 3pid registration and password resets
+
+    REMOTE = use an external server to send tokens
+    LOCAL = send tokens ourselves
+    OFF = disable registration via 3pid and password resets
+    """
+
+    REMOTE = "remote"
+    LOCAL = "local"
+    OFF = "off"

synapse/config/registration.py

@@ -99,6 +99,7 @@ def read_config(self, config, **kwargs):
         self.trusted_third_party_id_servers = config.get(
             "trusted_third_party_id_servers", ["matrix.org", "vector.im"]
         )
+        self.account_threepid_delegate = config.get("account_threepid_delegate")
         self.default_identity_server = config.get("default_identity_server")
         self.allow_guest_access = config.get("allow_guest_access", False)
 
@@ -269,6 +270,20 @@ def generate_config_section(self, generate_secrets=False, **kwargs):
         #  - matrix.org
         #  - vector.im
 
+        # Handle threepid (email/phone etc) registration and password resets
+        # through a *trusted* identity server. Note that this allows the configured
+        # identity server to reset passwords for accounts.
+        #
+        # If this option is not defined and SMTP options have not been
+        # configured, registration by email and resetting user passwords via
+        # email will be disabled
+        #
+        # Otherwise, to enable set this option to the reachable domain name, including protocol
+        # definition, for an identity server
+        # (e.g "https://matrix.org", "http://localhost:8090")
+        #
+        #account_threepid_delegate: ""
+
         # Users who register on this homeserver will automatically be joined
         # to these rooms
         #

synapse/handlers/auth.py

@@ -38,6 +38,7 @@
     UserDeactivatedError,
 )
 from synapse.api.ratelimiting import Ratelimiter
+from synapse.config.emailconfig import ThreepidBehaviour
 from synapse.logging.context import defer_to_thread
 from synapse.module_api import ModuleApi
 from synapse.types import UserID
@@ -460,10 +461,10 @@ def _check_threepid(self, medium, authdict, password_servlet=False, **kwargs):
         logger.info("Getting validated threepid. threepidcreds: %r", (threepid_creds,))
         if (
             not password_servlet
-            or self.hs.config.email_password_reset_behaviour == "remote"
+            or self.hs.config.email_threepid_behaviour == ThreepidBehaviour.REMOTE
         ):
             threepid = yield identity_handler.threepid_from_creds(threepid_creds)
-        elif self.hs.config.email_password_reset_behaviour == "local":
+        elif self.hs.config.email_threepid_behaviour == ThreepidBehaviour.LOCAL:
             row = yield self.store.get_threepid_validation_session(
                 medium,
                 threepid_creds["client_secret"],

synapse/handlers/identity.py

@@ -199,19 +199,46 @@ def try_unbind_threepid_with_id_server(self, mxid, threepid, id_server):
     def requestEmailToken(
         self, id_server, email, client_secret, send_attempt, next_link=None
     ):
+        """
+        Request an external server send an email on our behalf for the purposes of threepid
+        validation.
+
+        Args:
+            id_server (str|None): The identity server to send this through. If None,
+                use the server specified by the account_threepid_delegate config option
+            email (str): The email to send the message to
+            client_secret (str): The unique client_secret sends by the user
+            send_attempt (int): Which attempt this is
+            next_link: A link to redirect the user to once they submit the token
+
+        Returns:
+            The json response body from the server
+        """
         params = {
             "email": email,
             "client_secret": client_secret,
             "send_attempt": send_attempt,
         }
+        if next_link:
+            params["next_link"] = next_link
 
         if next_link:
             params.update({"next_link": next_link})
 
+        if not id_server:
+            if not self.hs.config.account_threepid_delegate:
+                raise SynapseError(
+                    400, "No id_server provided and none configured on the " "server"
+                )
+            id_server = self.hs.config.account_threepid_delegate
+        else:
+            # Assume "https://" is the protocol we're using to contact the id_server
+            # provided by the client
+            id_server = "https://" + id_server
+
         try:
             data = yield self.http_client.post_json_get_json(
-                "https://%s%s"
-                % (id_server, "/_matrix/identity/api/v1/validate/email/requestToken"),
+                id_server + "/_matrix/identity/api/v1/validate/email/requestToken",
                 params,
             )
             return data
@@ -221,20 +248,50 @@ def requestEmailToken(
 
     @defer.inlineCallbacks
     def requestMsisdnToken(
-        self, id_server, country, phone_number, client_secret, send_attempt, **kwargs
+        self,
+        id_server,
+        country,
+        phone_number,
+        client_secret,
+        send_attempt,
+        next_link=None,
     ):
+        """
+        Request an external server send an SMS message on our behalf for the purposes of
+        threepid validation.
+        Args:
+            country (str): The country code of the phone number
+            phone_number (str): The number to send the message to
+            client_secret (str): The unique client_secret sends by the user
+            send_attempt (int): Which attempt this is
+            next_link: A link to redirect the user to once they submit the token
+
+        Returns:
+            The json response body from the server
+        """
         params = {
             "country": country,
             "phone_number": phone_number,
             "client_secret": client_secret,
             "send_attempt": send_attempt,
         }
-        params.update(kwargs)
+        if next_link:
+            params["next_link"] = next_link
+
+        if not id_server:
+            if not self.hs.config.account_threepid_delegate:
+                raise SynapseError(
+                    400, "No id_server provided and none configured on the " "server"
+                )
+            id_server = self.hs.config.account_threepid_delegate
+        else:
+            # Assume "https://" is the protocol we're using to contact the id_server
+            # provided by the client
+            id_server = "https://" + id_server
 
         try:
             data = yield self.http_client.post_json_get_json(
-                "https://%s%s"
-                % (id_server, "/_matrix/identity/api/v1/validate/msisdn/requestToken"),
+                id_server + "/_matrix/identity/api/v1/validate/msisdn/requestToken",
                 params,
             )
             return data