feat: shared secret auth

.env.sample

@@ -111,3 +111,7 @@ ALLOWED_LIFETIME_MAX=4w
 #SECRET_SIGNAL_AS_TOKEN_VERSION=v1
 #SECRET_SIGNAL_DB_PASSWORD_VERSION=v1
 #SECRET_SIGNAL_HS_TOKEN_VERSION=v1
+
+#COMPOSE_FILE="$COMPOSE_FILE:compose.shared_secret_auth.yml"
+#SHARED_SECRET_AUTH_ENABLED=1
+#SECRET_SHARED_SECRET_AUTH_VERSION=v1 # length=128

abra.sh

@@ -1,6 +1,7 @@
 export ENTRYPOINT_CONF_VERSION=v1
-export HOMESERVER_YAML_VERSION=v12
+export HOMESERVER_YAML_VERSION=v13
 export LOG_CONFIG_VERSION=v2
-export TELEGRAM_BRIDGE_YAML_VERSION=v2
+export TELEGRAM_BRIDGE_YAML_VERSION=v3
 export DISCORD_BRIDGE_YAML_VERSION=v1
-export SIGNAL_BRIDGE_YAML_VERSION=v1
+export SIGNAL_BRIDGE_YAML_VERSION=v2
+export SHARED_SECRET_AUTH_VERSION=v1

compose.shared_secret_auth.yml

@@ -0,0 +1,22 @@
+---
+version: "3.8"
+
+services:
+  app:
+    environment:
+      - SHARED_SECRET_AUTH_ENABLED
+    secrets:
+      - shared_secret_auth
+    configs:
+      - source: shared_secret_auth
+        target: /usr/local/lib/python3.9/site-packages/shared_secret_authenticator.py
+
+configs:
+  shared_secret_auth:
+    name: ${STACK_NAME}_shared_secret_auth_${SHARED_SECRET_AUTH_VERSION}
+    file: shared_secret_authenticator.py
+
+secrets:
+  shared_secret_auth:
+    external: true
+    name: ${STACK_NAME}_shared_secret_auth_${SECRET_SHARED_SECRET_AUTH_VERSION}

homeserver.yaml.tmpl

@@ -20,7 +20,12 @@ modules:
     #       do_thing: true
     # - module: my_other_super_module.SomeClass
     #   config: {}
-
+    {{ if eq (env "SHARED_SECRET_AUTH_ENABLED") "1" }}
+    - module: shared_secret_authenticator.SharedSecretAuthProvider
+      config:
+        shared_secret: {{ secret "shared_secret_auth" }}
+        m_login_password_support_enabled: true
+    {{ end }}
 
 ## Server ##
 

shared_secret_authenticator.py

@@ -0,0 +1,123 @@
+# -*- coding: utf-8 -*-
+#
+# Shared Secret Authenticator module for Matrix Synapse
+# Copyright (C) 2018 Slavi Pantaleev
+#
+# https://devture.com/
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+from typing import Awaitable, Callable, Optional, Tuple
+
+import hashlib
+import hmac
+import logging
+
+import synapse
+from synapse import module_api
+
+logger = logging.getLogger(__name__)
+
+class SharedSecretAuthProvider:
+    def __init__(self, config: dict, api: module_api):
+        for k in ('shared_secret',):
+            if k not in config:
+                raise KeyError('Required `{0}` configuration key not found'.format(k))
+
+        m_login_password_support_enabled = bool(config['m_login_password_support_enabled']) if 'm_login_password_support_enabled' in config else False
+        com_devture_shared_secret_auth_support_enabled = bool(config['com_devture_shared_secret_auth_support_enabled']) if 'com_devture_shared_secret_auth_support_enabled' in config else True
+
+        self.api = api
+        self.shared_secret = config['shared_secret']
+
+        auth_checkers: Optional[Dict[Tuple[str, Tuple], CHECK_AUTH_CALLBACK]] = {}
+        if com_devture_shared_secret_auth_support_enabled:
+            auth_checkers[("com.devture.shared_secret_auth", ("token",))] = self.check_com_devture_shared_secret_auth
+        if m_login_password_support_enabled:
+            auth_checkers[("m.login.password", ("password",))] = self.check_m_login_password
+
+        enabled_login_types = [k[0] for k in auth_checkers]
+
+        if len(enabled_login_types) == 0:
+            raise RuntimeError('At least one login type must be enabled')
+
+        logger.info('Enabled login types: %s', enabled_login_types)
+
+        api.register_password_auth_provider_callbacks(
+            auth_checkers=auth_checkers,
+        )
+
+    async def check_com_devture_shared_secret_auth(
+        self,
+        username: str,
+        login_type: str,
+        login_dict: "synapse.module_api.JsonDict",
+    ) -> Optional[
+        Tuple[
+            str,
+            Optional[Callable[["synapse.module_api.LoginResponse"], Awaitable[None]]],
+        ]
+    ]:
+        if login_type != "com.devture.shared_secret_auth":
+            return None
+        return await self._log_in_username_with_token("com.devture.shared_secret_auth", username, login_dict.get("token"))
+
+    async def check_m_login_password(
+        self,
+        username: str,
+        login_type: str,
+        login_dict: "synapse.module_api.JsonDict",
+    ) -> Optional[
+        Tuple[
+            str,
+            Optional[Callable[["synapse.module_api.LoginResponse"], Awaitable[None]]],
+        ]
+    ]:
+        if login_type != "m.login.password":
+            return None
+        return await self._log_in_username_with_token("m.login.password", username, login_dict.get("password"))
+
+    async def _log_in_username_with_token(
+        self,
+        login_type: str,
+        username: str,
+        token: str,
+    ) -> Optional[
+        Tuple[
+            str,
+            Optional[Callable[["synapse.module_api.LoginResponse"], Awaitable[None]]],
+        ]
+    ]:
+        logger.info('Authenticating user `%s` with login type `%s`', username, login_type)
+
+        full_user_id = self.api.get_qualified_user_id(username)
+
+        # The password (token) is supposed to be an HMAC of the full user id, keyed with the shared secret.
+        given_hmac = token.encode('utf-8')
+
+        h = hmac.new(self.shared_secret.encode('utf-8'), full_user_id.encode('utf-8'), hashlib.sha512)
+        computed_hmac = h.hexdigest().encode('utf-8')
+
+        if not hmac.compare_digest(computed_hmac, given_hmac):
+            logger.info('Bad hmac value for user: %s', full_user_id)
+            return None
+
+        user_info = await self.api.get_userinfo_by_id(full_user_id)
+        if user_info is None:
+            logger.info('Refusing to authenticate missing user: %s', full_user_id)
+            return None
+
+        logger.info('Authenticated user: %s', full_user_id)
+
+        return full_user_id, None

signal_bridge.yaml.tmpl

@@ -145,7 +145,7 @@ bridge:
     double_puppet_allow_discovery: false
     # Servers to allow double puppeting from, even if double_puppet_allow_discovery is false.
     double_puppet_server_map:
-        example.com: https://example.com
+        {{ env "HOMESERVER_DOMAIN" }}: {{ env "HOMESERVER_URL" }}
     # Shared secret for https://github.com/devture/matrix-synapse-shared-secret-auth
     #
     # If set, custom puppets will be enabled automatically for local users
@@ -154,7 +154,7 @@ bridge:
     # If using this for other servers than the bridge's server,
     # you must also set the URL in the double_puppet_server_map.
     login_shared_secret_map:
-        example.com: foo
+        {{ env "HOMESERVER_DOMAIN" }}: {{ secret "shared_secret_auth" }}
     # Whether or not created rooms should have federation enabled.
     # If false, created portal rooms will never be federated.
     federate_rooms: true

telegram_bridge.yaml.tmpl

@@ -189,7 +189,7 @@ bridge:
     sync_direct_chat_list: false
     # Servers to always allow double puppeting from
     double_puppet_server_map:
-        example.com: https://example.com
+        {{ env "HOMESERVER_DOMAIN" }}: {{ env "HOMESERVER_URL" }}
     # Allow using double puppeting from any server with a valid client .well-known file.
     double_puppet_allow_discovery: false
     # Shared secrets for https://github.com/devture/matrix-synapse-shared-secret-auth
@@ -200,7 +200,7 @@ bridge:
     # If using this for other servers than the bridge's server,
     # you must also set the URL in the double_puppet_server_map.
     login_shared_secret_map:
-        example.com: foobar
+        {{ env "HOMESERVER_DOMAIN" }}: {{ secret "shared_secret_auth" }}
     # Set to false to disable link previews in messages sent to Telegram.
     telegram_link_preview: true
     # Whether or not the !tg join command should do a HTTP request