adding csrf check form functionality

Author: colevscode

docs/options.rst

@@ -157,6 +157,14 @@ These are only applicable if ``JWT_TOKEN_LOCATION`` is set to use cookies and
                                   Only applicable if ``JWT_CSRF_IN_COOKIES`` is ``True``
 ``JWT_REFRESH_CSRF_COOKIE_PATH``  Path of the CSRF refresh cookie. Defaults to ``'/'``.
                                   Only applicable if ``JWT_CSRF_IN_COOKIES`` is ``True``
+``JWT_CSRF_CHECK_FORM``           When no CSRF token can be found in the header, check the form data. Defaults to
+                                  ``False``.
+``JWT_ACCESS_CSRF_FIELD_NAME``    Name of the form field that should contain the CSRF double submit value for access
+                                  tokens when no header is present. Only applicable if ``JWT_CSRF_CHECK_FORM`` is
+                                  ``True``. Defaults to ``'csrf_token'``.
+``JWT_REFRESH_CSRF_FIELD_NAME``   Name of the form field that should contain the CSRF double submit value for refresh
+                                  tokens when no header is present. Only applicable if ``JWT_CSRF_CHECK_FORM`` is
+                                  ``True``. Defaults to ``'csrf_token'``.
 ================================= =========================================
 
 

docs/tokens_in_cookies.rst

@@ -78,3 +78,37 @@ to the caller, like such:
       set_access_cookies(resp, access_token)
       set_refresh_cookies(resp, refresh_token)
       return resp, 200
+
+
+Typically JWT is used with API servers using JSON payloads, often via AJAX. However you may have an endpoint that
+receives POST requests directly from an HTML form. Without AJAX, you can't set the CSRF headers to pass your token to
+the server. In this scenario you can send the token in a hidden form field. To accomplish this, first configure JWT to
+check the form for CSRF tokens:
+
+.. code-block:: python
+
+  app.config['JWT_CSRF_IN_COOKIES'] = True
+  app.config['JWT_CSRF_CHECK_FORM'] = True
+
+
+Then extract the CSRF token from the cookie and pass it to the server via a hidden form input.
+
+.. code-block:: html
+
+  <form id="my_form" method="POST">
+    ...
+    <input id="csrf_input" name="csrf_token" type="hidden">
+    <button>Submit</button>
+  </form>
+
+  <script>
+    function get_csrf_token() {
+      var cookie_name = "csrf_access_token";
+      var value = document.cookie.match('(^|;) ?' + cookie_name + '=([^;]*)(;|$)');
+      return value ? value[2] : null;
+    }
+    document.getElementById("my_form").addEventListener('submit', function() {
+      document.getElementById("csrf_input").value = get_csrf_token();
+    });
+  </script>
+

flask_jwt_extended/config.py

@@ -184,6 +184,18 @@ def refresh_csrf_header_name(self):
         return self._get_depreciated_csrf_header_name() or \
                current_app.config['JWT_REFRESH_CSRF_HEADER_NAME']
 
+    @property
+    def csrf_check_form(self):
+        return current_app.config['JWT_CSRF_CHECK_FORM']
+
+    @property
+    def access_csrf_field_name(self):
+        return current_app.config['JWT_ACCESS_CSRF_FIELD_NAME']
+
+    @property
+    def refresh_csrf_field_name(self):
+        return current_app.config['JWT_REFRESH_CSRF_FIELD_NAME']
+
     @property
     def access_expires(self):
         delta = current_app.config['JWT_ACCESS_TOKEN_EXPIRES']

flask_jwt_extended/jwt_manager.py

@@ -196,6 +196,9 @@ def _set_default_configuration_options(app):
         app.config.setdefault('JWT_REFRESH_CSRF_COOKIE_NAME', 'csrf_refresh_token')
         app.config.setdefault('JWT_ACCESS_CSRF_COOKIE_PATH', '/')
         app.config.setdefault('JWT_REFRESH_CSRF_COOKIE_PATH', '/')
+        app.config.setdefault('JWT_CSRF_CHECK_FORM', False)
+        app.config.setdefault('JWT_ACCESS_CSRF_FIELD_NAME', 'csrf_token')
+        app.config.setdefault('JWT_REFRESH_CSRF_FIELD_NAME', 'csrf_token')
 
         # How long an a token will live before they expire.
         app.config.setdefault('JWT_ACCESS_TOKEN_EXPIRES', datetime.timedelta(minutes=15))

flask_jwt_extended/view_decorators.py

@@ -198,18 +198,22 @@ def _decode_jwt_from_cookies(request_type):
     if request_type == 'access':
         cookie_key = config.access_cookie_name
         csrf_header_key = config.access_csrf_header_name
+        csrf_field_key = config.access_csrf_field_name
     else:
         cookie_key = config.refresh_cookie_name
         csrf_header_key = config.refresh_csrf_header_name
+        csrf_field_key = config.refresh_csrf_field_name
 
     encoded_token = request.cookies.get(cookie_key)
     if not encoded_token:
         raise NoAuthorizationError('Missing cookie "{}"'.format(cookie_key))
 
     if config.csrf_protect and request.method in config.csrf_request_methods:
         csrf_value = request.headers.get(csrf_header_key, None)
+        if not csrf_value and config.csrf_check_form:
+            csrf_value = request.form.get(csrf_field_key, None)
         if not csrf_value:
-            raise CSRFError("Missing CSRF token in headers")
+            raise CSRFError("Missing CSRF token")
     else:
         csrf_value = None
 

tests/test_cookies.py

@@ -139,7 +139,7 @@ def test_default_access_csrf_protection(app, options):
     # Test you cannot post without the additional csrf protection
     response = test_client.post(post_url)
     assert response.status_code == 401
-    assert response.get_json() == {'msg': 'Missing CSRF token in headers'}
+    assert response.get_json() == {'msg': 'Missing CSRF token'}
 
     # Test that you can post with the csrf double submit value
     csrf_headers = {'X-CSRF-TOKEN': csrf_token}
@@ -201,6 +201,48 @@ def test_csrf_with_custom_header_names(app, options):
     assert response.get_json() == {'foo': 'bar'}
 
 
+@pytest.mark.parametrize("options", [
+    ('/refresh_token', 'csrf_refresh_token', '/post_refresh_protected'),
+    ('/access_token', 'csrf_access_token', '/post_protected')
+])
+def test_csrf_with_default_form_field(app, options):
+    app.config['JWT_CSRF_CHECK_FORM'] = True
+    test_client = app.test_client()
+    auth_url, csrf_cookie_name, post_url = options
+
+    # Get the jwt cookies and csrf double submit tokens
+    response = test_client.get(auth_url)
+    csrf_token = _get_cookie_from_response(response, csrf_cookie_name)[csrf_cookie_name]
+
+    # Test that you can post with the csrf double submit value
+    csrf_data = {'csrf_token': csrf_token}
+    response = test_client.post(post_url, data=csrf_data)
+    assert response.status_code == 200
+    assert response.get_json() == {'foo': 'bar'}
+
+
+@pytest.mark.parametrize("options", [
+    ('/refresh_token', 'csrf_refresh_token', '/post_refresh_protected'),
+    ('/access_token', 'csrf_access_token', '/post_protected')
+])
+def test_csrf_with_custom_form_field(app, options):
+    app.config['JWT_CSRF_CHECK_FORM'] = True
+    app.config['JWT_ACCESS_CSRF_FIELD_NAME'] = 'FOO'
+    app.config['JWT_REFRESH_CSRF_FIELD_NAME'] = 'FOO'
+    test_client = app.test_client()
+    auth_url, csrf_cookie_name, post_url = options
+
+    # Get the jwt cookies and csrf double submit tokens
+    response = test_client.get(auth_url)
+    csrf_token = _get_cookie_from_response(response, csrf_cookie_name)[csrf_cookie_name]
+
+    # Test that you can post with the csrf double submit value
+    csrf_data = {'FOO': csrf_token}
+    response = test_client.post(post_url, data=csrf_data)
+    assert response.status_code == 200
+    assert response.get_json() == {'foo': 'bar'}
+
+
 @pytest.mark.parametrize("options", [
     ('/refresh_token', 'csrf_refresh_token', '/refresh_protected', '/post_refresh_protected'),  # nopep8
     ('/access_token', 'csrf_access_token', '/protected', '/post_protected')
@@ -222,7 +264,7 @@ def test_custom_csrf_methods(app, options):
     # Insure GET requests now fail without csrf
     response = test_client.get(get_url)
     assert response.status_code == 401
-    assert response.get_json() == {'msg': 'Missing CSRF token in headers'}
+    assert response.get_json() == {'msg': 'Missing CSRF token'}
 
     # Insure GET requests now succeed with csrf
     csrf_headers = {'X-CSRF-TOKEN': csrf_token}
@@ -430,4 +472,4 @@ def test_jwt_optional_with_csrf_enabled(app):
     csrf_token = csrf_cookie['csrf_access_token']
     response = test_client.post('/optional_post_protected')
     assert response.status_code == 401
-    assert response.get_json() == {'msg': 'Missing CSRF token in headers'}
+    assert response.get_json() == {'msg': 'Missing CSRF token'}