-
http://lists.freedesktop.org/archives/polkit-devel/2015-June/000425.html The "cookie" value that Polkit hands out is global to all polkit users. And when `AuthenticationAgentResponse` is invoked, we previously only received the cookie and *target* identity, and attempted to find an agent from that. The problem is that the current cookie is just an integer counter, and if it overflowed, it would be possible for an successful authorization in one session to trigger a response in another session. The overflow and ability to guess the cookie were fixed by the previous patch. This patch is conceptually further hardening on top of that. Polkit currently treats uids as equivalent from a security domain perspective; there is no support for SELinux/AppArmor/etc. differentiation. We can retrieve the uid from `getuid()` in the setuid helper, which allows us to ensure the uid invoking `AuthenticationAgentResponse2` matches that of the agent. Then the authority only looks at authentication sessions matching the cookie that were created by a matching uid, thus removing the ability for different uids to interfere with each other entirely. Several fixes to this patch were contributed by: Miloslav Trmač <mitr@redhat.com> Bug: https://bugs.freedesktop.org/show_bug.cgi?id=90837 CVE: CVE-2015-4625 Reported-by: Tavis Ormandy <taviso@google.com> Reviewed-by: Miloslav Trmač <mitr@redhat.com> Signed-off-by: Colin Walters <walters@redhat.com>
493aa5dc