Since we merged cd2348e9ae more than a
month ago and haven't seen any noticable regresions as a result, it's
reasonable at this point to do a corresponding decrease in our
documented RAM requirements for the Zulip development environment.
Like the recent change blocking JSON endpoints for deactivated users
and users in deactivated realms, this change is a hardening
improvement. Those users should be unable to get an active session
anyway, but if somehow one is leaked, this means they won't be able to
access any user data.
Previously, api_fetch_api_key would not give clear error messages if
password auth was disabled or the user's realm had been deactivated;
additionally, the account disabled error stopped triggering when we
moved the active account check into the auth decorators.
While in theory users should be unable to get a valid session in order
to access these endpoints in the first place, this provides an extra
layer of hardering to prevent a deactivated user with a session from
accessing data via the old-style JSON API.
The security model for deactivated users (and users in deactivated
realms) being unable to access the service is intended to work via two
mechanisms:
* All active user sessions are deleted, and all login code paths
(where a user could get a new session) check whether the user (or
realm) is inactive before authorizing the request, preventing the
user from accessing the website and AJAX endpoints.
* All API code paths (which don't require a session) check whether the
user (and realm) are active.
However, this security model was not implemented correctly. In
particular, the check for whether a user has an active account in the
login process was done inside the login form's validators, which meant
that authentication mechanisms that did not use the login form
(e.g. Google and REMOTE_USER auth) could succeed in granting a session
even with an inactive account. The Zulip homepage would still fail to
load because the code for / includes an API call to Tornado authorized
by the user's token that would fail, but this mechanism could allow an
inactive user to access realm data or users to access data in a
deactivated realm.
This fixes the issue by adding explicit checks for inactive users and
inactive realms in all authentication backends (even those that were
already protected by the login form validator).
Mirror dummy users are already inactive, so we can remove the explicit
code around mirror dummy users.
The following commits add a complete set of tests for Zulip's inactive
user and realm security model.
In a deactivated realm, webhooks would still successfully send
messages, since there was no check for whether the realm was active in
api_key_only_webhook_view.
Tomasz Kolek
Eklavya Sharma
Sumana Harihareswara
Tim Abbott
Umair Khan
Tom
Bert Muthalaly