Add an option to have authentication enabled for all endpoints by default

jupyter_server/auth/decorator.py

@@ -85,3 +85,58 @@ async def inner(self, *args, **kwargs):
         return cast(FuncT, wrapper(method))
 
     return cast(FuncT, wrapper)
+
+
+def allow_unauthenticated(method: FuncT) -> FuncT:
+    """A decorator for tornado.web.RequestHandler methods
+    that allows any user to make the following request.
+
+    Selectively disables the 'authentication' layer of REST API which
+    is active when `ServerApp.allow_unauthenticated_access = False`.
+
+    To be used exclusively on endpoints which may be considered public,
+    for example the login page handler.
+
+    .. versionadded:: 2.13
+
+    Parameters
+    ----------
+    method : bound callable
+        the endpoint method to remove authentication from.
+    """
+
+    @wraps(method)
+    def wrapper(self, *args, **kwargs):
+        return method(self, *args, **kwargs)
+
+    setattr(wrapper, "__allow_unauthenticated", True)
+
+    return cast(FuncT, wrapper)
+
+
+def ws_authenticated(method: FuncT) -> FuncT:
+    """A decorator for websockets derived from `WebSocketHandler`
+    that authenticates user before allowing to proceed.
+
+    Differently from tornado.web.authenticated, does not redirect
+    to the login page, which would be meaningless for websockets.
+
+    .. versionadded:: 2.13
+
+    Parameters
+    ----------
+    method : bound callable
+        the endpoint method to add authentication for.
+    """
+
+    @wraps(method)
+    def wrapper(self, *args, **kwargs):
+        user = self.current_user
+        if user is None:
+            self.log.warning("Couldn't authenticate WebSocket connection")
+            raise HTTPError(403)
+        return method(self, *args, **kwargs)
+
+    setattr(wrapper, "__allow_unauthenticated", False)
+
+    return cast(FuncT, wrapper)

jupyter_server/auth/login.py

@@ -9,6 +9,7 @@
 from tornado.escape import url_escape
 
 from ..base.handlers import JupyterHandler
+from .decorator import allow_unauthenticated
 from .security import passwd_check, set_password
 
 
@@ -73,6 +74,7 @@ def _redirect_safe(self, url, default=None):
                 url = default
         self.redirect(url)
 
+    @allow_unauthenticated
     def get(self):
         """Get the login form."""
         if self.current_user:
@@ -81,6 +83,7 @@ def get(self):
         else:
             self._render()
 
+    @allow_unauthenticated
     def post(self):
         """Post a login."""
         user = self.current_user = self.identity_provider.process_login_form(self)
@@ -110,6 +113,7 @@ def passwd_check(self, a, b):
         """Check a passwd."""
         return passwd_check(a, b)
 
+    @allow_unauthenticated
     def post(self):
         """Post a login form."""
         typed_password = self.get_argument("password", default="")

jupyter_server/auth/logout.py

@@ -3,11 +3,13 @@
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
 from ..base.handlers import JupyterHandler
+from .decorator import allow_unauthenticated
 
 
 class LogoutHandler(JupyterHandler):
     """An auth logout handler."""
 
+    @allow_unauthenticated
     def get(self):
         """Handle a logout."""
         self.identity_provider.clear_login_cookie(self)

jupyter_server/base/handlers.py

@@ -14,7 +14,7 @@
 import warnings
 from http.client import responses
 from logging import Logger
-from typing import TYPE_CHECKING, Any, Awaitable, Sequence, cast
+from typing import TYPE_CHECKING, Any, Awaitable, Coroutine, Sequence, cast
 from urllib.parse import urlparse
 
 import prometheus_client
@@ -29,7 +29,7 @@
 from jupyter_server import CallContext
 from jupyter_server._sysinfo import get_sys_info
 from jupyter_server._tz import utcnow
-from jupyter_server.auth.decorator import authorized
+from jupyter_server.auth.decorator import allow_unauthenticated, authorized
 from jupyter_server.auth.identity import User
 from jupyter_server.i18n import combine_translations
 from jupyter_server.services.security import csp_report_uri
@@ -630,6 +630,16 @@ async def prepare(self) -> Awaitable[None] | None:  # type:ignore[override]
         self.set_cors_headers()
         if self.request.method not in {"GET", "HEAD", "OPTIONS"}:
             self.check_xsrf_cookie()
+
+        if not self.settings.get("allow_unauthenticated_access", False):
+            if not self.request.method:
+                raise HTTPError(403)
+            method = getattr(self, self.request.method.lower())
+            if not getattr(method, "__allow_unauthenticated", False):
+                # reuse `web.authenticated` logic, which redirects to the login
+                # page on GET and HEAD and otherwise raises 403
+                return web.authenticated(lambda _method: None)(self)
+
         return super().prepare()
 
     # ---------------------------------------------------------------
@@ -794,6 +804,7 @@ def finish(self, *args: Any, **kwargs: Any) -> Future[Any]:
         self.set_header("Content-Type", set_content_type)
         return super().finish(*args, **kwargs)
 
+    @allow_unauthenticated
     def options(self, *args: Any, **kwargs: Any) -> None:
         """Get the options."""
         if "Access-Control-Allow-Headers" in self.settings.get("headers", {}):
@@ -1002,6 +1013,18 @@ def compute_etag(self) -> str | None:
         """Compute the etag."""
         return None
 
+    # access is allowed as this class is used to serve static assets on login page
+    # TODO: create an allow-list of files used on login page and remove this decorator
+    @allow_unauthenticated
+    def get(self, path: str, include_body: bool = True) -> Coroutine[Any, Any, None]:
+        return super().get(path, include_body)
+
+    # access is allowed as this class is used to serve static assets on login page
+    # TODO: create an allow-list of files used on login page and remove this decorator
+    @allow_unauthenticated
+    def head(self, path: str) -> Awaitable[None]:
+        return super().head(path)
+
     @classmethod
     def get_absolute_path(cls, roots: Sequence[str], path: str) -> str:
         """locate a file to serve on our static file search path"""
@@ -1036,6 +1059,7 @@ class APIVersionHandler(APIHandler):
 
     _track_activity = False
 
+    @allow_unauthenticated
     def get(self) -> None:
         """Get the server version info."""
         # not authenticated, so give as few info as possible
@@ -1048,6 +1072,7 @@ class TrailingSlashHandler(web.RequestHandler):
     This should be the first, highest priority handler.
     """
 
+    @allow_unauthenticated
     def get(self) -> None:
         """Handle trailing slashes in a get."""
         assert self.request.uri is not None
@@ -1064,6 +1089,7 @@ def get(self) -> None:
 class MainHandler(JupyterHandler):
     """Simple handler for base_url."""
 
+    @allow_unauthenticated
     def get(self) -> None:
         """Get the main template."""
         html = self.render_template("main.html")
@@ -1104,18 +1130,20 @@ async def redirect_to_files(self: Any, path: str) -> None:
         self.log.debug("Redirecting %s to %s", self.request.path, url)
         self.redirect(url)
 
+    @allow_unauthenticated
     async def get(self, path: str = "") -> None:
         return await self.redirect_to_files(self, path)
 
 
 class RedirectWithParams(web.RequestHandler):
-    """Sam as web.RedirectHandler, but preserves URL parameters"""
+    """Same as web.RedirectHandler, but preserves URL parameters"""
 
     def initialize(self, url: str, permanent: bool = True) -> None:
         """Initialize a redirect handler."""
         self._url = url
         self._permanent = permanent
 
+    @allow_unauthenticated
     def get(self) -> None:
         """Get a redirect."""
         sep = "&" if "?" in self._url else "?"
@@ -1128,6 +1156,7 @@ class PrometheusMetricsHandler(JupyterHandler):
     Return prometheus metrics for this server
     """
 
+    @allow_unauthenticated
     def get(self) -> None:
         """Get prometheus metrics."""
         if self.settings["authenticate_prometheus"] and not self.logged_in:
@@ -1137,6 +1166,18 @@ def get(self) -> None:
         self.write(prometheus_client.generate_latest(prometheus_client.REGISTRY))
 
 
+class PublicStaticFileHandler(web.StaticFileHandler):
+    """Same as web.StaticFileHandler, but decorated to acknowledge that auth is not required."""
+
+    @allow_unauthenticated
+    def head(self, path: str) -> Awaitable[None]:
+        return super().head(path)
+
+    @allow_unauthenticated
+    def get(self, path: str, include_body: bool = True) -> Coroutine[Any, Any, None]:
+        return super().get(path, include_body)
+
+
 # -----------------------------------------------------------------------------
 # URL pattern fragments for reuse
 # -----------------------------------------------------------------------------
@@ -1152,6 +1193,6 @@ def get(self) -> None:
 default_handlers = [
     (r".*/", TrailingSlashHandler),
     (r"api", APIVersionHandler),
-    (r"/(robots\.txt|favicon\.ico)", web.StaticFileHandler),
+    (r"/(robots\.txt|favicon\.ico)", PublicStaticFileHandler),
     (r"/metrics", PrometheusMetricsHandler),
 ]

jupyter_server/base/websocket.py

@@ -3,7 +3,7 @@
 from typing import Optional, no_type_check
 from urllib.parse import urlparse
 
-from tornado import ioloop
+from tornado import ioloop, web
 from tornado.iostream import IOStream
 
 # ping interval for keeping websockets alive (30 seconds)
@@ -82,6 +82,27 @@ def check_origin(self, origin: Optional[str] = None) -> bool:
     def clear_cookie(self, *args, **kwargs):
         """meaningless for websockets"""
 
+    @no_type_check
+    def _maybe_auth(self):
+        """Verify authentication if required"""
+        if not self.settings.get("allow_unauthenticated_access", False):
+            if not self.request.method:
+                raise web.HTTPError(403)
+            method = getattr(self, self.request.method.lower())
+            if not getattr(method, "__allow_unauthenticated", False):
+                # rather than re-using `web.authenticated` which also redirects
+                # to login page on GET, just raise 403 if user is not known
+                user = self.current_user
+                if user is None:
+                    self.log.warning("Couldn't authenticate WebSocket connection")
+                    raise web.HTTPError(403)
+
+    @no_type_check
+    def prepare(self, *args, **kwargs):
+        """Handle a get request."""
+        self._maybe_auth()
+        return super().prepare(*args, **kwargs)
+
     @no_type_check
     def open(self, *args, **kwargs):
         """Open the websocket."""

jupyter_server/extension/application.py

@@ -358,7 +358,7 @@ def _prepare_handlers(self):
             )
             new_handlers.append(handler)
 
-        webapp.add_handlers(".*$", new_handlers)  # type:ignore[arg-type]
+        webapp.add_handlers(".*$", new_handlers)
 
     def _prepare_templates(self):
         """Add templates to web app settings if extension has templates."""