LCFG authorization

The authorization of LCFG component methods (which are called using the om command) is typically done using the LCFG::Authorize module. This is limited to checking usernames and membership of groups managed in LCFG.

In Informatics we have for a long-time used a different module – DICE::Authorize – which extends this to also checking membership of a netgroup. Recently we discovered some problems with our implementation of this functionality which make it very inflexible. We have been connecting directly to the LDAP server and doing the lookup based on hardcoded information in the module. As this really just boils down to checking membership of a netgroup this can clearly be done more simply by calling the innetgr function. This will work via the standard NS framework so will handle LDAP, NIS or whatever is required. The necessary details are then only stored in the standard location and not embedded into the code.

Rather than just rewrite the DICE::Authorize module I took the chance to move the functionality to the LCFG layer, so we now have LCFG::Authorize::NetGroups. This nicely sub-classes the standard module so that if the user is not a member of a netgroup the other checks are then carried out. This is much better code reuse, previously we had two distinct implementations of the basic checks.

Having a new implementation of the authorization module is also handy for dealing with the transition stage. We can keep the old one around so that if a problem is discovered with the new code we can quickly switch back to the old code.

I also took the chance to improve the documentation of the authorization framework so if you’re still running om as root now is a good time to improve things!

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