Consolidate logic to check for deactivated users.

changelog.d/15634.bugfix

@@ -0,0 +1 @@
+Fix a long-standing bug where deactivated users were able to login in uncommon situations.

docs/modules/password_auth_provider_callbacks.md

@@ -46,6 +46,9 @@ instead.
 
 If the authentication is unsuccessful, the module must return `None`.
 
+Note that the user is not automatically registered, the `register_user(..)` method of
+the [module API](writing_a_module.html) can be used to lazily create users.
+
 If multiple modules register an auth checker for the same login type but with different
 fields, Synapse will refuse to start.
 

synapse/appservice/__init__.py

@@ -86,6 +86,7 @@ def __init__(
             url.rstrip("/") if isinstance(url, str) else None
         )  # url must not end with a slash
         self.hs_token = hs_token
+        # The full Matrix ID for this application service's sender.
         self.sender = sender
         self.namespaces = self._check_namespaces(namespaces)
         self.id = id
@@ -212,7 +213,7 @@ def is_interested_in_user(
             True if the application service is interested in the user, False if not.
         """
         return (
-            # User is the appservice's sender_localpart user
+            # User is the appservice's configured sender_localpart user
             user_id == self.sender
             # User is in the appservice's user namespace
             or self.is_user_in_namespace(user_id)

synapse/handlers/auth.py

@@ -52,7 +52,6 @@
     NotFoundError,
     StoreError,
     SynapseError,
-    UserDeactivatedError,
 )
 from synapse.api.ratelimiting import Ratelimiter
 from synapse.handlers.ui_auth import (
@@ -1419,12 +1418,6 @@ async def _check_local_password(self, user_id: str, password: str) -> Optional[s
             return None
         (user_id, password_hash) = lookupres
 
-        # If the password hash is None, the account has likely been deactivated
-        if not password_hash:
-            deactivated = await self.store.get_user_deactivated_status(user_id)
-            if deactivated:
-                raise UserDeactivatedError("This account has been deactivated")
-
         result = await self.validate_hash(password, password_hash)
         if not result:
             logger.warning("Failed password login for user %s", user_id)
@@ -1749,8 +1742,11 @@ async def complete_sso_login(
                 registered.
             auth_provider_session_id: The session ID from the SSO IdP received during login.
         """
-        # If the account has been deactivated, do not proceed with the login
-        # flow.
+        # If the account has been deactivated, do not proceed with the login.
+        #
+        # This gets checked again when the token is submitted but this lets us
+        # provide an HTML error page to the user (instead of issuing a token and
+        # having it error later).
         deactivated = await self.store.get_user_deactivated_status(registered_user_id)
         if deactivated:
             respond_with_html(request, 403, self._sso_account_deactivated_template)

synapse/handlers/jwt.py

@@ -16,7 +16,7 @@
 from authlib.jose import JsonWebToken, JWTClaims
 from authlib.jose.errors import BadSignatureError, InvalidClaimError, JoseError
 
-from synapse.api.errors import Codes, LoginError, StoreError, UserDeactivatedError
+from synapse.api.errors import Codes, LoginError
 from synapse.types import JsonDict, UserID
 
 if TYPE_CHECKING:
@@ -26,15 +26,14 @@
 class JwtHandler:
     def __init__(self, hs: "HomeServer"):
         self.hs = hs
-        self._main_store = hs.get_datastores().main
 
         self.jwt_secret = hs.config.jwt.jwt_secret
         self.jwt_subject_claim = hs.config.jwt.jwt_subject_claim
         self.jwt_algorithm = hs.config.jwt.jwt_algorithm
         self.jwt_issuer = hs.config.jwt.jwt_issuer
         self.jwt_audiences = hs.config.jwt.jwt_audiences
 
-    async def validate_login(self, login_submission: JsonDict) -> str:
+    def validate_login(self, login_submission: JsonDict) -> str:
         """
         Authenticates the user for the /login API
 
@@ -103,16 +102,4 @@ async def validate_login(self, login_submission: JsonDict) -> str:
         if user is None:
             raise LoginError(403, "Invalid JWT", errcode=Codes.FORBIDDEN)
 
-        user_id = UserID(user, self.hs.hostname).to_string()
-
-        # If the account has been deactivated, do not proceed with the login
-        # flow.
-        try:
-            deactivated = await self._main_store.get_user_deactivated_status(user_id)
-        except StoreError:
-            # JWT lazily creates users, so they may not exist in the database yet.
-            deactivated = False
-        if deactivated:
-            raise UserDeactivatedError("This account has been deactivated")
-
-        return user_id
+        return UserID(user, self.hs.hostname).to_string()

synapse/rest/client/login.py

@@ -35,6 +35,7 @@
     LoginError,
     NotApprovedError,
     SynapseError,
+    UserDeactivatedError,
 )
 from synapse.api.ratelimiting import Ratelimiter
 from synapse.api.urls import CLIENT_API_PREFIX
@@ -84,6 +85,7 @@ class LoginRestServlet(RestServlet):
     def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.hs = hs
+        self._main_store = hs.get_datastores().main
 
         # JWT configuration variables.
         self.jwt_enabled = hs.config.jwt.jwt_enabled
@@ -112,13 +114,13 @@ def __init__(self, hs: "HomeServer"):
 
         self._well_known_builder = WellKnownBuilder(hs)
         self._address_ratelimiter = Ratelimiter(
-            store=hs.get_datastores().main,
+            store=self._main_store,
             clock=hs.get_clock(),
             rate_hz=self.hs.config.ratelimiting.rc_login_address.per_second,
             burst_count=self.hs.config.ratelimiting.rc_login_address.burst_count,
         )
         self._account_ratelimiter = Ratelimiter(
-            store=hs.get_datastores().main,
+            store=self._main_store,
             clock=hs.get_clock(),
             rate_hz=self.hs.config.ratelimiting.rc_login_account.per_second,
             burst_count=self.hs.config.ratelimiting.rc_login_account.burst_count,
@@ -280,6 +282,9 @@ async def _do_appservice_login(
             login_submission,
             ratelimit=appservice.is_rate_limited(),
             should_issue_refresh_token=should_issue_refresh_token,
+            # The user represented by an appservice's configured sender_localpart
+            # is not actually created in Synapse.
+            should_check_deactivated=qualified_user_id != appservice.sender,
         )
 
     async def _do_other_login(
@@ -326,6 +331,7 @@ async def _complete_login(
         auth_provider_id: Optional[str] = None,
         should_issue_refresh_token: bool = False,
         auth_provider_session_id: Optional[str] = None,
+        should_check_deactivated: bool = True,
     ) -> LoginResponse:
         """Called when we've successfully authed the user and now need to
         actually login them in (e.g. create devices). This gets called on
@@ -345,6 +351,11 @@ async def _complete_login(
             should_issue_refresh_token: True if this login should issue
                 a refresh token alongside the access token.
             auth_provider_session_id: The session ID got during login from the SSO IdP.
+            should_check_deactivated: True if the user should be checked for
+                deactivation status before logging in.
+
+                This exists purely for appservice's configured sender_localpart
+                which doesn't have an associated user in the database.
 
         Returns:
             Dictionary of account information after successful login.
@@ -364,6 +375,12 @@ async def _complete_login(
                 )
             user_id = canonical_uid
 
+        # If the account has been deactivated, do not proceed with the login.
+        if should_check_deactivated:
+            deactivated = await self._main_store.get_user_deactivated_status(user_id)
+            if deactivated:
+                raise UserDeactivatedError("This account has been deactivated")
+
         device_id = login_submission.get("device_id")
 
         # If device_id is present, check that device_id is not longer than a reasonable 512 characters
@@ -458,7 +475,7 @@ async def _do_jwt_login(
         Returns:
             The body of the JSON response.
         """
-        user_id = await self.hs.get_jwt_handler().validate_login(login_submission)
+        user_id = self.hs.get_jwt_handler().validate_login(login_submission)
         return await self._complete_login(
             user_id,
             login_submission,

tests/handlers/test_password_providers.py

@@ -18,13 +18,17 @@
 from typing import Any, Dict, List, Optional, Type, Union
 from unittest.mock import Mock
 
+from twisted.test.proto_helpers import MemoryReactor
+
 import synapse
 from synapse.api.constants import LoginType
 from synapse.api.errors import Codes
 from synapse.handlers.account import AccountHandler
 from synapse.module_api import ModuleApi
 from synapse.rest.client import account, devices, login, logout, register
+from synapse.server import HomeServer
 from synapse.types import JsonDict, UserID
+from synapse.util import Clock
 
 from tests import unittest
 from tests.server import FakeChannel
@@ -162,10 +166,16 @@ class PasswordAuthProviderTests(unittest.HomeserverTestCase):
     CALLBACK_USERNAME = "get_username_for_registration"
     CALLBACK_DISPLAYNAME = "get_displayname_for_registration"
 
-    def setUp(self) -> None:
+    def prepare(
+        self, reactor: MemoryReactor, clock: Clock, homeserver: HomeServer
+    ) -> None:
         # we use a global mock device, so make sure we are starting with a clean slate
         mock_password_provider.reset_mock()
-        super().setUp()
+
+        # The mock password provider doesn't register the users, so ensure they
+        # are registered first.
+        self.register_user("u", "not-the-tested-password")
+        self.register_user("user", "not-the-tested-password")
 
     @override_config(legacy_providers_config(LegacyPasswordOnlyAuthProvider))
     def test_password_only_auth_progiver_login_legacy(self) -> None:
@@ -185,33 +195,19 @@ def password_only_auth_provider_login_test_body(self) -> None:
         mock_password_provider.reset_mock()
 
         # login with mxid should work too
-        channel = self._send_password_login("@u:bz", "p")
+        channel = self._send_password_login("@u:test", "p")
         self.assertEqual(channel.code, HTTPStatus.OK, channel.result)
-        self.assertEqual("@u:bz", channel.json_body["user_id"])
-        mock_password_provider.check_password.assert_called_once_with("@u:bz", "p")
+        self.assertEqual("@u:test", channel.json_body["user_id"])
+        mock_password_provider.check_password.assert_called_once_with("@u:test", "p")
         mock_password_provider.reset_mock()
 
-        # try a weird username / pass. Honestly it's unclear what we *expect* to happen
-        # in these cases, but at least we can guard against the API changing
-        # unexpectedly
-        channel = self._send_password_login(" USER🙂NAME ", " pASS\U0001F622word ")
-        self.assertEqual(channel.code, HTTPStatus.OK, channel.result)
-        self.assertEqual("@ USER🙂NAME :test", channel.json_body["user_id"])
-        mock_password_provider.check_password.assert_called_once_with(
-            "@ USER🙂NAME :test", " pASS😢word "
-        )
-
     @override_config(legacy_providers_config(LegacyPasswordOnlyAuthProvider))
     def test_password_only_auth_provider_ui_auth_legacy(self) -> None:
         self.password_only_auth_provider_ui_auth_test_body()
 
     def password_only_auth_provider_ui_auth_test_body(self) -> None:
         """UI Auth should delegate correctly to the password provider"""
 
-        # create the user, otherwise access doesn't work
-        module_api = self.hs.get_module_api()
-        self.get_success(module_api.register_user("u"))
-
         # log in twice, to get two devices
         mock_password_provider.check_password.return_value = make_awaitable(True)
         tok1 = self.login("u", "p")
@@ -401,29 +397,16 @@ def custom_auth_provider_login_test_body(self) -> None:
         mock_password_provider.check_auth.assert_not_called()
 
         mock_password_provider.check_auth.return_value = make_awaitable(
-            ("@user:bz", None)
+            ("@user:test", None)
         )
         channel = self._send_login("test.login_type", "u", test_field="y")
         self.assertEqual(channel.code, HTTPStatus.OK, channel.result)
-        self.assertEqual("@user:bz", channel.json_body["user_id"])
+        self.assertEqual("@user:test", channel.json_body["user_id"])
         mock_password_provider.check_auth.assert_called_once_with(
             "u", "test.login_type", {"test_field": "y"}
         )
         mock_password_provider.reset_mock()
 
-        # try a weird username. Again, it's unclear what we *expect* to happen
-        # in these cases, but at least we can guard against the API changing
-        # unexpectedly
-        mock_password_provider.check_auth.return_value = make_awaitable(
-            ("@ MALFORMED! :bz", None)
-        )
-        channel = self._send_login("test.login_type", " USER🙂NAME ", test_field=" abc ")
-        self.assertEqual(channel.code, HTTPStatus.OK, channel.result)
-        self.assertEqual("@ MALFORMED! :bz", channel.json_body["user_id"])
-        mock_password_provider.check_auth.assert_called_once_with(
-            " USER🙂NAME ", "test.login_type", {"test_field": " abc "}
-        )
-
     @override_config(legacy_providers_config(LegacyCustomAuthProvider))
     def test_custom_auth_provider_ui_auth_legacy(self) -> None:
         self.custom_auth_provider_ui_auth_test_body()
@@ -465,7 +448,7 @@ def custom_auth_provider_ui_auth_test_body(self) -> None:
 
         # right params, but authing as the wrong user
         mock_password_provider.check_auth.return_value = make_awaitable(
-            ("@user:bz", None)
+            ("@user:test", None)
         )
         body["auth"]["test_field"] = "foo"
         channel = self._delete_device(tok1, "dev2", body)
@@ -498,11 +481,11 @@ def custom_auth_provider_callback_test_body(self) -> None:
         callback = Mock(return_value=make_awaitable(None))
 
         mock_password_provider.check_auth.return_value = make_awaitable(
-            ("@user:bz", callback)
+            ("@user:test", callback)
         )
         channel = self._send_login("test.login_type", "u", test_field="y")
         self.assertEqual(channel.code, HTTPStatus.OK, channel.result)
-        self.assertEqual("@user:bz", channel.json_body["user_id"])
+        self.assertEqual("@user:test", channel.json_body["user_id"])
         mock_password_provider.check_auth.assert_called_once_with(
             "u", "test.login_type", {"test_field": "y"}
         )
@@ -512,7 +495,7 @@ def custom_auth_provider_callback_test_body(self) -> None:
         call_args, call_kwargs = callback.call_args
         # should be one positional arg
         self.assertEqual(len(call_args), 1)
-        self.assertEqual(call_args[0]["user_id"], "@user:bz")
+        self.assertEqual(call_args[0]["user_id"], "@user:test")
         for p in ["user_id", "access_token", "device_id", "home_server"]:
             self.assertIn(p, call_args[0])