From d75bf80d063e880984d0ac30ef9ac63ed7ee21bb Mon Sep 17 00:00:00 2001
From: Gonzalo Gasca Meza <gogasca@google.com>
Date: Fri, 25 Oct 2024 10:38:06 -0700
Subject: [PATCH] CORS is not checked when browsing files. check origin now
 https://github.com/jupyter-server/jupyter_server/issues/1459

---
 jupyter_server/base/handlers.py |   2 +
 tests/base/test_handlers.py     | 107 ++++++++++++++++++++++++++++++++
 2 files changed, 109 insertions(+)

diff --git a/jupyter_server/base/handlers.py b/jupyter_server/base/handlers.py
index 770fff1866..9a47b2f68c 100644
--- a/jupyter_server/base/handlers.py
+++ b/jupyter_server/base/handlers.py
@@ -534,6 +534,8 @@ def check_xsrf_cookie(self) -> None:
             # Servers without authentication are vulnerable to XSRF
             return None
         try:
+            if not self.check_origin():
+                raise web.HTTPError(404)
             return super().check_xsrf_cookie()
         except web.HTTPError as e:
             if self.request.method in {"GET", "HEAD"}:
diff --git a/tests/base/test_handlers.py b/tests/base/test_handlers.py
index 6d8dce90da..2b5490e90f 100644
--- a/tests/base/test_handlers.py
+++ b/tests/base/test_handlers.py
@@ -8,6 +8,7 @@
 from tornado.httpclient import HTTPClientError
 from tornado.httpserver import HTTPRequest
 from tornado.httputil import HTTPHeaders
+from tornado.web import HTTPError
 
 from jupyter_server.auth import AllowAllAuthorizer, IdentityProvider, User
 from jupyter_server.auth.decorator import allow_unauthenticated
@@ -137,6 +138,112 @@ async def test_jupyter_handler_auth_required(jp_serverapp, jp_fetch):
     assert exception.value.code == 403
 
 
+@pytest.mark.parametrize(
+    "token_authenticated, disable_check_xsrf, method, check_origin, expected_result",
+    [
+        (True, False, "POST", True, None),  # Token-authenticated requests bypass XSRF check
+        (False, True, "POST", True, None),  # XSRF check disabled
+        (False, False, "GET", True, None),  # GET requests don't require XSRF check
+        (False, False, "POST", True, HTTPError),  # Non-authenticated POST should raise HTTPError
+        (False, False, "POST", False, HTTPError),  # Failed origin check should raise HTTPError
+    ],
+)
+async def test_check_xsrf_cookie(
+    jp_serverapp, token_authenticated, disable_check_xsrf, method, check_origin, expected_result
+):
+    class MockHandler(JupyterHandler):
+        def __init__(self, *args, **kwargs):
+            super().__init__(*args, **kwargs)
+            self._token_authenticated = token_authenticated
+            self.request.method = method
+            self.settings["disable_check_xsrf"] = disable_check_xsrf
+            self.settings["xsrf_cookies"] = True
+            self._current_user = True
+
+            # Initialize headers if not present
+            if not hasattr(self.request, "headers"):
+                self.request.headers = {}
+
+            # For POST requests that should fail XSRF check
+            if method == "POST" and not token_authenticated and not disable_check_xsrf:
+                # Explicitly set mismatched tokens for failing case
+                self._xsrf_token = "server_token"
+                self.request.headers["_xsrf"] = "different_token"
+                self._cookies = {"_xsrf": MagicMock(value="server_token")}
+            else:
+                # For passing cases, set matching tokens
+                self._xsrf_token = "mock_xsrf_token"
+                self.request.headers["_xsrf"] = "mock_xsrf_token"
+                self._cookies = {"_xsrf": MagicMock(value="mock_xsrf_token")}
+
+            # Add referer header for GET requests
+            if method == "GET":
+                self.request.headers["Referer"] = "http://localhost"
+
+        @property
+        def token_authenticated(self):
+            return self._token_authenticated
+
+        @property
+        def current_user(self):
+            return self._current_user
+
+        def check_origin(self):
+            return check_origin
+
+        def check_referer(self):
+            return True
+
+        def get_cookie(self, name, default=None):
+            if hasattr(self, "_cookies") and name in self._cookies:
+                return self._cookies[name].value
+            return default
+
+        def check_xsrf_cookie(self):
+            if self.token_authenticated or self.settings.get("disable_check_xsrf", False):
+                return None
+
+            if not self.check_origin():
+                raise HTTPError(404)
+
+            if (
+                self.request.method not in {"GET", "HEAD", "OPTIONS"}
+                and not self.token_authenticated
+            ):
+                # Get the cookie
+                cookie_token = self.get_cookie("_xsrf")
+                # Get the token from header
+                header_token = self.request.headers.get("_xsrf")
+
+                if not cookie_token:
+                    raise HTTPError(403, "'_xsrf' cookie not present")
+                if not header_token:
+                    raise HTTPError(403, "'_xsrf' argument missing")
+                if cookie_token != header_token:
+                    raise HTTPError(403, "XSRF cookie does not match")
+
+            return None
+
+    # Set up the request
+    request = HTTPRequest(method)
+    request.connection = MagicMock()
+    request.headers = {}
+
+    # Set up the application
+    app = jp_serverapp
+    app.web_app.settings["xsrf_cookies"] = True
+
+    # Create and initialize the handler
+    handler = MockHandler(app.web_app, request)
+
+    if expected_result is None:
+        # Should not raise an exception
+        handler.check_xsrf_cookie()
+    else:
+        with pytest.raises(expected_result):
+            handler.check_xsrf_cookie()
+
+
 @pytest.mark.parametrize(
     "jp_server_config", [{"ServerApp": {"allow_unauthenticated_access": False}}]
 )