enable jwt auth with feature flag

lms/envs/common.py

@@ -2147,6 +2147,14 @@ if FEATURES.get('CLASS_DASHBOARD'):
 ENABLE_CREDIT_ELIGIBILITY = True
 FEATURES['ENABLE_CREDIT_ELIGIBILITY'] = ENABLE_CREDIT_ELIGIBILITY
 
+################ Enable JWT auth ####################
+# When this feature flag is set to False, API endpoints using
+# JSONWebTokenAuthentication will reject requests using JWT to authenticate,
+# even if those tokens are valid. Set this to True only if you need those
+# endpoints, and have configured settings 'JWT_AUTH' to override its default
+# values with secure values.
+FEATURES['ENABLE_JWT_AUTH'] = False
+
 ######################## CAS authentication ###########################
 
 if FEATURES.get('AUTH_USE_CAS'):

openedx/core/lib/api/jwt_decode_handler.py

@@ -7,7 +7,9 @@ doesn't expose settings to enforce this.
 """
 import logging
 
+from django.conf import settings
 import jwt
+from rest_framework import exceptions
 from rest_framework_jwt.settings import api_settings
 
 
@@ -19,6 +21,10 @@ def decode(token):
     Ensure InvalidTokenErrors are logged for diagnostic purposes, before
     failing authentication.
     """
+    if not settings.FEATURES.get('ENABLE_JWT_AUTH', False):
+        msg = 'JWT auth not supported.'
+        log.error(msg)
+        raise exceptions.AuthenticationFailed(msg)
 
     options = {
         'verify_exp': api_settings.JWT_VERIFY_EXPIRATION,

openedx/core/lib/api/tests/mixins.py

+"""
+Mixins for JWT auth tests.
+"""
+from time import time
+
+from django.conf import settings
+import jwt
+
+
+JWT_AUTH = 'JWT_AUTH'
+
+
+class JwtMixin(object):
+    """ Mixin with JWT-related helper functions. """
+
+    JWT_SECRET_KEY = getattr(settings, JWT_AUTH)['JWT_SECRET_KEY'] if hasattr(settings, JWT_AUTH) else ''
+    JWT_ISSUER = getattr(settings, JWT_AUTH)['JWT_ISSUER'] if hasattr(settings, JWT_AUTH) else ''
+    JWT_AUDIENCE = getattr(settings, JWT_AUTH)['JWT_AUDIENCE'] if hasattr(settings, JWT_AUTH) else ''
+
+    def generate_token(self, payload, secret=None):
+        """ Generate a JWT token with the provided payload."""
+        secret = secret or self.JWT_SECRET_KEY
+        token = jwt.encode(payload, secret)
+        return token
+
+    def generate_id_token(self, user, ttl=1, **overrides):
+        """ Generate a JWT id_token that looks like the ones currently
+        returned by the edx oidc provider.
+        """
+        payload = self.default_payload(user=user, ttl=ttl)
+        payload.update(overrides)
+        return self.generate_token(payload)
+
+    def default_payload(self, user, ttl=1):
+        """ Generate a bare payload, in case tests need to manipulate
+        it directly before encoding.
+        """
+        now = int(time())
+
+        return {
+            "iss": self.JWT_ISSUER,
+            "aud": self.JWT_AUDIENCE,
+            "nonce": "dummy-nonce",
+            "exp": now + ttl,
+            "iat": now,
+            "username": user.username,
+            "email": user.email,
+        }

openedx/core/lib/api/tests/test_authentication.py

@@ -10,25 +10,31 @@ import itertools
 import json
 
 import ddt
+from django.conf import settings
 from django.conf.urls import patterns, url, include
 from django.contrib.auth.models import User
 from django.http import HttpResponse
 from django.test import TestCase
 from django.utils import unittest
 from django.utils.http import urlencode
-
+from mock import patch
+from rest_framework import exceptions
 from rest_framework import status
 from rest_framework.permissions import IsAuthenticated
 from rest_framework_oauth import permissions
 from rest_framework_oauth.compat import oauth2_provider, oauth2_provider_scope
 from rest_framework.test import APIRequestFactory, APIClient
 from rest_framework.views import APIView
+from rest_framework_jwt.settings import api_settings
 
-from provider import scope, constants
 from openedx.core.lib.api import authentication
+from openedx.core.lib.api.tests.mixins import JwtMixin
+from provider import constants, scope
+from student.tests.factories import UserFactory
 
 
 factory = APIRequestFactory()  # pylint: disable=invalid-name
+jwt_decode_handler = api_settings.JWT_DECODE_HANDLER    # pylint: disable=invalid-name
 
 
 class MockView(APIView):  # pylint: disable=missing-docstring
@@ -284,3 +290,31 @@ class OAuth2Tests(TestCase):
         self.assertEqual(response.status_code, scope_statuses.read_status)
         response = self.post_with_bearer_token('/oauth2-with-scope-test/', token=self.access_token.token)
         self.assertEqual(response.status_code, scope_statuses.write_status)
+
+
+@ddt.ddt
+@unittest.skipUnless(settings.ROOT_URLCONF == 'lms.urls', 'Test only valid in lms')
+class TestJWTAuthToggle(JwtMixin, TestCase):
+    """ Test JWT authentication toggling with feature flag 'ENABLE_JWT_AUTH'."""
+
+    USERNAME = 'test-username'
+
+    def setUp(self):
+        self.user = UserFactory.create(username=self.USERNAME)
+        self.jwt_token = self.generate_id_token(user=self.user)
+        super(TestJWTAuthToggle, self).setUp()
+
+    @patch.dict('django.conf.settings.FEATURES', {'ENABLE_JWT_AUTH': True})
+    def test_enabled_jwt_auth(self):
+        """ Ensure that the JWT auth works fine when its feature flag
+        'ENABLE_JWT_AUTH' is set.
+        """
+        jwt_decode_handler(self.jwt_token)
+
+    @patch.dict('django.conf.settings.FEATURES', {'ENABLE_JWT_AUTH': False})
+    def test_disabled_jwt_auth(self):
+        """ Ensure that the JWT auth raises exception when its feature flag
+        'ENABLE_JWT_AUTH' is not set.
+        """
+        with self.assertRaises(exceptions.AuthenticationFailed):
+            jwt_decode_handler(self.jwt_token)