Merge pull request #2940 from kinow/add-more-docs-for-cookies

[doc] Add more docs about Cookies used for authentication in JupyterHub

docs/source/getting-started/security-basics.rst

@@ -80,6 +80,49 @@ To achieve this, simply omit the configuration settings
 ``c.JupyterHub.ssl_key`` and ``c.JupyterHub.ssl_cert``
 (setting them to ``None`` does not have the same effect, and is an error).
 
+.. _authentication-token:
+
+Proxy authentication token
+--------------------------
+
+The Hub authenticates its requests to the Proxy using a secret token that
+the Hub and Proxy agree upon. Note that this applies to the default
+``ConfigurableHTTPProxy`` implementation. Not all proxy implementations
+use an auth token.
+
+The value of this token should be a random string (for example, generated by
+``openssl rand -hex 32``). You can store it in the configuration file or an
+environment variable
+
+Generating and storing token in the configuration file
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+You can set the value in the configuration file, ``jupyterhub_config.py``:
+
+.. code-block:: python
+
+    c.ConfigurableHTTPProxy.api_token = 'abc123...' # any random string
+
+Generating and storing as an environment variable
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+You can pass this value of the proxy authentication token to the Hub and Proxy
+using the ``CONFIGPROXY_AUTH_TOKEN`` environment variable:
+
+.. code-block:: bash
+
+    export CONFIGPROXY_AUTH_TOKEN=$(openssl rand -hex 32)
+
+This environment variable needs to be visible to the Hub and Proxy.
+
+Default if token is not set
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If you don't set the Proxy authentication token, the Hub will generate a random
+key itself, which means that any time you restart the Hub you **must also
+restart the Proxy**. If the proxy is a subprocess of the Hub, this should happen
+automatically (this is the default configuration).
+
 .. _cookie-secret:
 
 Cookie secret
@@ -146,41 +189,73 @@ itself, ``jupyterhub_config.py``, as a binary string:
    If the cookie secret value changes for the Hub, all single-user notebook
    servers must also be restarted.
 
+.. _cookies:
 
-.. _authentication-token:
+Cookies used by JupyterHub authentication
+-----------------------------------------
 
-Proxy authentication token
---------------------------
+The following cookies are used by the Hub for handling user authentication.
 
-The Hub authenticates its requests to the Proxy using a secret token that
-the Hub and Proxy agree upon. The value of this string should be a random
-string (for example, generated by ``openssl rand -hex 32``).
+This section was created based on this post_ from Discourse.
 
-Generating and storing token in the configuration file
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+.. _post: https://discourse.jupyter.org/t/how-to-force-re-login-for-users/1998/6
 
-Or you can set the value in the configuration file, ``jupyterhub_config.py``:
+jupyterhub-hub-login
+~~~~~~~~~~~~~~~~~~~~
 
-.. code-block:: python
+This is the login token used when visiting Hub-served pages that are
+protected by authentication such as the main home, the spawn form, etc.
+If this cookie is set, then the user is logged in.
 
-    c.JupyterHub.proxy_auth_token = '0bc02bede919e99a26de1e2a7a5aadfaf6228de836ec39a05a6c6942831d8fe5'
+Resetting the Hub cookie secret effectively revokes this cookie.
 
-Generating and storing as an environment variable
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+This cookie is restricted to the path ``/hub/``.
 
-You can pass this value of the proxy authentication token to the Hub and Proxy
-using the ``CONFIGPROXY_AUTH_TOKEN`` environment variable:
+jupyterhub-user-<username>
+~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-.. code-block:: bash
+This is the cookie used for authenticating with a single-user server.
+It is set by the single-user server after OAuth with the Hub.
 
-    export CONFIGPROXY_AUTH_TOKEN=$(openssl rand -hex 32)
+Effectively the same as ``jupyterhub-hub-login``, but for the
+single-user server instead of the Hub. It contains an OAuth access token,
+which is checked with the Hub to authenticate the browser.
 
-This environment variable needs to be visible to the Hub and Proxy.
+Each OAuth access token is associated with a session id (see ``jupyterhub-session-id`` section
+below).
 
-Default if token is not set
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
+To avoid hitting the Hub on every request, the authentication response
+is cached. And to avoid a stale cache the cache key is comprised of both
+the token and session id.
 
-If you don't set the Proxy authentication token, the Hub will generate a random
-key itself, which means that any time you restart the Hub you **must also
-restart the Proxy**. If the proxy is a subprocess of the Hub, this should happen
-automatically (this is the default configuration).
+Resetting the Hub cookie secret effectively revokes this cookie.
+
+This cookie is restricted to the path ``/user/<username>``, so that
+only the user’s server receives it.
+
+jupyterhub-session-id
+~~~~~~~~~~~~~~~~~~~~~
+
+This is a random string, meaningless in itself, and the only cookie
+shared by the Hub and single-user servers.
+
+Its sole purpose is to to coordinate logout of the multiple OAuth cookies.
+
+This cookie is set to ``/`` so all endpoints can receive it, or clear it, etc.
+
+jupyterhub-user-<username>-oauth-state
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A short-lived cookie, used solely to store and validate OAuth state.
+It is only set while OAuth between the single-user server and the Hub
+is processing.
+
+If you use your browser development tools, you should see this cookie
+for a very brief moment before your are logged in,
+with an expiration date shorter than ``jupyterhub-hub-login`` or
+``jupyterhub-user-<username>``.
+
+This cookie should not exist after you have successfully logged in.
+
+This cookie is restricted to the path ``/user/<username>``, so that only
+the user’s server receives it.