PasswordState, Active Directory and Sudo: oh my!

2018-01-10 20:14:00

Recently I've gone over a number of options of connecting a Linux environment in an existing Active Directory domain. I won't go into the customer's specifics, but after considering Winbind, SSSD, old school LDAP and commercial offerings like PBIS we went with the modern-yet-free SSSD-based solution. The upside of this approach is that integration is quick and easy. Not much manual labor needed at all. 

What's even cooler, is that SSSD supports sudoers rulesets by default!

With a few tiny adjustments to your configuration and after loading the relevant schema into AD, you're set to go! Jakub Hrozek wrote instructions a while back; they couldn't be simpler!

So now we have AD-based user logins and Sudo rules! That's pretty neat, because not only is our user management centralized, so is the full administration of Sudo! No need to manage /etc/sudoers and /etc/sudoers.d on all your boxen! Config management tools like Puppet or Ansible might make that easier, but one central repo is even nicer! :D

 


 

Now, I've been working with the PasswordState password management platform for a few weeks and so far I love it. Before getting the logins+Sudo centralized, getting the right privileged accounts on the Linux boxen was a bit of a headache. Well, not anymore! What's even cooler, is that using Sudo+LDAP improves upon a design limitation of PasswordState!

Due to the way their plugins are built, Click Studios say you need -two- privileged accounts to manage Linux passwords (source, chapter 14). One that has Defaults:privuser rootpw in sudoers and one that doesn't. All because of how the root password gets validated with the heartbeat script. With Sudoers residing in LDAP this problem goes away! I quote (from the sudoers.ldap man-page):

It is possible to specify per-entry options that override the global default options. /etc/sudoers only supports default options and limited options associated with user/host/commands/aliases. The syntax is complicated and can be difficult for users to understand. Placing the options directly in the entry is more natural.

Would you look at that! :) That means that, per the current build of PasswordState, the privileged user for Linux account management needs the following three sudoers entries in AD / LDAP. 

CN=pstate-ECHO,OU=sudoers,OU=domain,OU=local:
sudoHost = ALL
sudoCommand = /usr/bin/echo
sudoOption = rootpw
sudoUser = pstate

CN=pstate-PASSWDROOT,OU=sudoers,OU=domain,OU=local:
sudoHost = ALL
sudoCommand = /usr/bin/passwd root
sudoOption = rootpw
sudoOrder = 10
sudoUser = pstate

CN=pstate-PASSWD,OU=sudoers,OU=domain,OU=local:
sudoHost = ALL
sudoCommand = /usr/bin/passwd *
sudoUser = pstate

The "sudo echo" is used to validate the root password (because the rootpw option is applied). I only applied the rootpw option to "sudo passwd root" to maintain compatibility with the default script included with PasswordState


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