On Mon, 2019-09-23 at 22:53 +0200, Lukas Slebodnik wrote: > On (23/09/19 15:55), Simo Sorce wrote: > > On Mon, 2019-09-23 at 14:39 -0500, Spike White wrote: > > > All, > > > > > > Our cybersecurity team doesn’t allow Linux sysadmins to directly log in as > > > root. (violates accountability, auditability and traceability). We log > > > in > > > with an ADM account, which is then eligible to become root via ‘sudo su > > > –‘. > > > > > > That is, all members of a particular group are allowed to sudo to root. > > > > > > This is preferred because with modern sudo versions all sudo sessions are > > > session-logged. > > > > > > Anyway, if I log in with my ADM account and someone shuts down sssd, it no > > > longer knows what groups I’m in. That is, the session is still there – > > > but > > > it cannot look up the group names. > > > > > > [admspike_white@zzzdmsdev06 ~]$ id > > > > > > uid=2025431 gid=1002 groups=1002,2284295 > > > > > > > > > > > > Because the sudo privs are based on group name, it doesn’t allow Linux > > > sysadmins to become root and thus start sssd. > > > > > > > > > > > > Is there a way to cache those group names and memberships? Say with nscd? > > > So that if sssd is (temporarily) shut down, we can become root and start > > > up? > > > > sssd already caches user and group tables for fast lookup, but those > > caches are not very big, so if you have very many groups you may need > > to increase the size. > > > > Also these caches have somewhat strict timeouts, I forget if they stop > > returning anything at all if the timeout is expired. > > > > > > The behaviour of fast mmap cache is to fall back to daemon in case of > expired entry. Which is by default just 5 minutes. > And if sssd is not running then it will not return anything. > > > > Obviously, we can go look up the root password for the particular server – > > > but that’s a painful portal. It’d be better if we could cache group names > > > and memberships, if sssd is temporarily down or offline. > > > > Perhaps an RFE to return whatever was in cachi, even if expired, if > > sssd daemons are unresponsive may be opened, should that be the > > behavior when caches timed out. > > > > > > I do not see a reason why sssd should be temporarily down. > If there is a crash then it should be restarted by systemd. > If sssd is running but in offline mode then it should return even > expired entries from the cache. > > I would say the biggest problem in the description is > "someone shuts down sssd". And just somebody with root privileges can do that. > But if sb has root(sudo) access then it can break anything there (even sshd) > And thus nobody can connect there. What would you do in such situation?
Not sure what would you do with a rouge admin, but there can definitely be cases where sssd will refuse to start, for example if an admin fat- fingers the config file, in that case allowing the fast cache to be used would save the day. So I think that regardless of how sssd can end up in a state where it is not running it may be useful to allow to return whatever information we have so that the system is more recoverable, after all the information there may be stale, but it is not incorrect. That said if sudo rules are served via SSSD there may be issues there too, but that is another story. Simo. -- Simo Sorce RHEL Crypto Team Red Hat, Inc _______________________________________________ sssd-users mailing list -- sssd-users@lists.fedorahosted.org To unsubscribe send an email to sssd-users-le...@lists.fedorahosted.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedorahosted.org/archives/list/sssd-users@lists.fedorahosted.org
