Add support for Referrer-Policy

README.md

@@ -119,6 +119,11 @@ or minimum configuration.
 <td><b>DEPRECATED: </b>Will be removed in future releases.<br/>Adds the HTTP header attribute specifying compact P3P policy.
 <td>Required.
 
+<tr>
+<td><a href="http://django-security.readthedocs.org/en/latest/#security.middleware.ReferrerPolicyMiddleware">ReferrerPolicyMiddleware</a>
+<td>Specify when the browser will set a `Referer` header.
+<td>Optional.
+
 <tr>
 <td><a href="http://django-security.readthedocs.org/en/latest/#security.middleware.SessionExpiryPolicyMiddleware">SessionExpiryPolicyMiddleware</a>
 <td>Expire sessions on browser close, and on expiry times stored in the cookie itself.

security/middleware.py

@@ -17,7 +17,7 @@
 from django.utils.deprecation import MiddlewareMixin
 import django.views.static
 
-from ua_parser.user_agent_parser import ParseUserAgent
+from ua_parser import user_agent_parser
 
 
 logger = logging.getLogger(__name__)
@@ -901,7 +901,7 @@ def process_response(self, request, response):
         # choose headers based enforcement mode
         is_ie = False
         if 'HTTP_USER_AGENT' in request.META:
-            parsed_ua = ParseUserAgent(request.META['HTTP_USER_AGENT'])
+            parsed_ua = user_agent_parser.ParseUserAgent(request.META['HTTP_USER_AGENT'])
             is_ie = parsed_ua['family'] == 'IE'
 
         csp_header = 'Content-Security-Policy'
@@ -1315,3 +1315,56 @@ def process_request(self, request):
             login_url = login_url + '?next=' + next_url
 
         return HttpResponseRedirect(login_url)
+
+class ReferrerPolicyMiddleware(BaseMiddleware):
+    """
+    Sends Referrer-Policy HTTP header that controls when the browser will set
+    the `Referer` header. Use REFERRER_POLICY option in settings file
+    with the following values:
+
+      - ``no-referrer``
+      - ``no-referrer-when-downgrade``
+      - ``origin``
+      - ``origin-when-cross-origin``
+      - ``same-origin`` (*default*)
+      - ``strict-origin``
+      - ``strict-origin-when-cross-origin``
+      - ``unsafe-url``
+      - ``off``
+
+    Reference:
+    - `Referrer-Policy from Mozilla Developer Network
+      <https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Referrer-Policy>`
+    """
+
+    OPTIONAL_SETTINGS = ("REFERRER_POLICY",)
+
+    OPTIONS = [ 'no-referrer', 'no-referrer-when-downgrade', 'origin',
+    'origin-when-cross-origin', 'same-origin', 'strict-origin',
+    'strict-origin-when-cross-origin', 'unsafe-url', 'off' ]
+
+    DEFAULT = 'same-origin'
+
+    def load_setting(self, setting, value):
+        if not value:
+            self.option = self.DEFAULT
+            return
+
+        value = value.lower()
+
+        if value in self.OPTIONS:
+            self.option = value
+            return
+
+        raise ImproperlyConfigured(
+            self.__class__.__name__ + " invalid option for REFERRER_POLICY."
+        )
+
+    def process_response(self, request, response):
+        """
+        Add Referrer-Policy to the reponse header.
+        """
+        if self.option != 'off':
+            header = self.option
+            response['Referrer-Policy'] = header
+        return response

setup.py

@@ -6,7 +6,7 @@
 from distutils.core import Command
 from setuptools import setup
 
-with open(os.path.join(os.path.dirname(__file__), 'README.md')) as f:
+with open(os.path.join(os.path.dirname(__file__), "README.md")) as f:
     readme = f.read()
 
 
@@ -20,37 +20,44 @@ def finalize_options(self):
         pass
 
     def run(self):
-        errno = subprocess.call([sys.executable, 'testing/manage.py', 'test'])
+        errno = subprocess.call([sys.executable, "testing/manage.py", "test"])
         raise SystemExit(errno)
 
-setup(name="django-security",
-      description='A collection of tools to help secure a Django project.',
-      long_description=readme,
-      long_description_content_type='text/markdown',
-      maintainer="SD Elements",
-      maintainer_email="[email protected]",
-      version="0.13.2",
-      packages=["security", "security.south_migrations",
-                "security.migrations", "security.auth_throttling"],
-      url='https://github.com/sdelements/django-security',
-      classifiers=[
-          'Framework :: Django',
-          'Framework :: Django :: 1.11',
-          'Framework :: Django :: 2.2',
-          'Framework :: Django :: 3.0',
-          'Environment :: Web Environment',
-          'Programming Language :: Python',
-          'Programming Language :: Python :: 3',
-          'Programming Language :: Python :: 3.6',
-          'Intended Audience :: Developers',
-          'Operating System :: OS Independent',
-          'License :: OSI Approved :: BSD License',
-          'Topic :: Software Development :: Libraries :: Python Modules',
-          'Topic :: Security',
-      ],
-      install_requires=[
-          'django>=1.11',
-          'ua_parser>=0.7.1',
-          'python-dateutil==2.8.1',
-      ],
-      cmdclass={'test': Test})
+
+setup(
+    name="django-security",
+    description="A collection of tools to help secure a Django project.",
+    long_description=readme,
+    long_description_content_type="text/markdown",
+    maintainer="SD Elements",
+    maintainer_email="[email protected]",
+    version="0.13.2",
+    packages=[
+        "security",
+        "security.south_migrations",
+        "security.migrations",
+        "security.auth_throttling",
+    ],
+    url="https://github.com/sdelements/django-security",
+    classifiers=[
+        "Framework :: Django",
+        "Framework :: Django :: 1.11",
+        "Framework :: Django :: 2.2",
+        "Framework :: Django :: 3.0",
+        "Environment :: Web Environment",
+        "Programming Language :: Python",
+        "Programming Language :: Python :: 3",
+        "Programming Language :: Python :: 3.6",
+        "Intended Audience :: Developers",
+        "Operating System :: OS Independent",
+        "License :: OSI Approved :: BSD License",
+        "Topic :: Software Development :: Libraries :: Python Modules",
+        "Topic :: Security",
+    ],
+    install_requires=[
+        "django>=1.11",
+        "ua_parser>=0.7.1",
+        "python-dateutil==2.8.1",
+    ],
+    cmdclass={"test": Test},
+)

testing/settings.py

@@ -50,6 +50,7 @@
     'security.middleware.MandatoryPasswordChangeMiddleware',
     'security.middleware.NoConfidentialCachingMiddleware',
     'security.auth_throttling.Middleware',
+    'security.middleware.ReferrerPolicyMiddleware',
 )
 
 ROOT_URLCONF = 'testing.urls'

testing/tests/tests.py

@@ -24,7 +24,7 @@
 from security.middleware import (
     BaseMiddleware, ContentSecurityPolicyMiddleware, DoNotTrackMiddleware,
     SessionExpiryPolicyMiddleware, MandatoryPasswordChangeMiddleware,
-    XssProtectMiddleware, XFrameOptionsMiddleware,
+    XssProtectMiddleware, XFrameOptionsMiddleware, ReferrerPolicyMiddleware
 )
 from security.models import PasswordExpiry
 from security.password_expiry import never_expire_password
@@ -1064,24 +1064,70 @@ def test_DNT_echo_default(self):
         self.dnt.process_response(self.request, self.response)
         self.assertNotIn('DNT', self.response)
 
+class ReferrerPolicyTests(TestCase):
 
-@override_settings(MIDDLEWARE=(
-    'security.middleware.ClearSiteDataMiddleware',
-))
-class ClearSiteDataMiddlewareTests(TestCase):
-    def test_request_that_matches_the_whitelist_with_default_directives(self):
-        response = self.client.get('/home/')
-        self.assertEqual(response['Clear-Site-Data'], '"cookies", "storage"')
+    def test_option_set(self):
+        """
+        Verify the HTTP Referrer-Policy Header is set.
+        """
+        response = self.client.get('/accounts/login/')
+        self.assertNotEqual(response['Referrer-Policy'], None)
 
-    def test_request_that_misses_the_whitelist(self):
-        response = self.client.get('/test1/')
-        self.assertNotIn("Clear-Site-Data", response)
+    def test_default_setting(self):
+        with self.settings(REFERRER_POLICY=None):
+            response = self.client.get('/accounts/login/')
+            self.assertEqual(response['Referrer-Policy'], 'same-origin')
 
-    @override_settings(CLEAR_SITE_DATA_DIRECTIVES=(
-        'cache', 'cookies', 'executionContexts', '*'
-    ))
-    def test_request_that_matches_the_whitelist_with_custom_directives(self):
-        response = self.client.get('/home/')
-        self.assertEqual(
-            response['Clear-Site-Data'],
-            '"cache", "cookies", "executionContexts", "*"')
+    def test_no_referrer_setting(self):
+        with self.settings(REFERRER_POLICY='no-referrer'):
+            response = self.client.get('/accounts/login/')
+            self.assertEqual(response['Referrer-Policy'], 'no-referrer')
+
+    def test_no_referrer_when_downgrade_setting(self):
+        with self.settings(REFERRER_POLICY='no-referrer-when-downgrade'):
+            response = self.client.get('/accounts/login/')
+            self.assertEqual(response['Referrer-Policy'], 'no-referrer-when-downgrade')
+
+    def test_origin_setting(self):
+        with self.settings(REFERRER_POLICY='origin'):
+            response = self.client.get('/accounts/login/')
+            self.assertEqual(response['Referrer-Policy'], 'origin')
+
+    def test_origin_when_cross_origin_setting(self):
+        with self.settings(REFERRER_POLICY='origin-when-cross-origin'):
+            response = self.client.get('/accounts/login/')
+            self.assertEqual(response['Referrer-Policy'], 'origin-when-cross-origin')
+
+    def test_same_origin_setting(self):
+        with self.settings(REFERRER_POLICY='same-origin'):
+            response = self.client.get('/accounts/login/')
+            self.assertEqual(response['Referrer-Policy'], 'same-origin')
+
+    def test_strict_origin_setting(self):
+        with self.settings(REFERRER_POLICY='strict-origin'):
+            response = self.client.get('/accounts/login/')
+            self.assertEqual(response['Referrer-Policy'], 'strict-origin')
+
+    def test_strict_origin_when_cross_origin_setting(self):
+        with self.settings(REFERRER_POLICY='strict-origin-when-cross-origin'):
+            response = self.client.get('/accounts/login/')
+            self.assertEqual(response['Referrer-Policy'], 'strict-origin-when-cross-origin')
+
+    def test_unsafe_url_setting(self):
+        with self.settings(REFERRER_POLICY='unsafe-url'):
+            response = self.client.get('/accounts/login/')
+            self.assertEqual(response['Referrer-Policy'], 'unsafe-url')
+
+    def test_off_setting(self):
+        with self.settings(REFERRER_POLICY='off'):
+            response = self.client.get('/accounts/login/')
+            self.assertEqual('Referrer-Policy' in response, False)
+
+    def test_improper_configuration_raises(self):
+        referer_policy_middleware = ReferrerPolicyMiddleware()
+        self.assertRaises(
+            ImproperlyConfigured,
+            referer_policy_middleware.load_setting,
+            'REFERRER_POLICY',
+            'invalid',
+        )