Subject: Re: [ldapext] draft-behera-ldap-password-policy - operational attrs

From: Howard Chu <[email-masked]>
Date: Tue, 26 Apr 2005 07:41:49 -0700

I kept meaning to raise this question, but it seems to have fallen thru 
the cracks. For the OpenLDAP implementation, I needed to change these 
operational attributes to NO-USER-MODIFICATION:
	pwdChangedTime, pwdGraceUseTime, and pwdHistory

We have a problem because of the way we process a password change - if a 
user is changing their own password, that Modify request is performed 
using the user's identity. To do bookkeeping on the above operational 
attributes, we internally append some modify operations to the user's 
Modify request, and then the augmented request is passed down to the 
usual Modify processing. One other factor in our implementation is that 
user-modifiable attributes are subject to ACL checks, non-modifiable 
attributes are not. So, userPassword is user-modifiable, and typically 
users are given permission to write their own password. But they 
shouldn't have permission to write the above three attributes, because 
then they can just bypass a lot of the policies that rely on those 
attributes.

So with the default definitions, we have a problem because the user may 
have permission to update the userPassword attr, but no permissions to 
the other attrs.

Alternatively we can break things up into two separate Modify 
operations, doing the user's original request and then using system 
privileges to handle the bookkeeping, but I'm not keen on that approach. 
It introduces some lag in a replication scenario, where the password 
change itself will get replicated separately from the bookkeeping update.

Fundamentally I believe NO-USER-MODIFICATION is appropriate for these 
attributes. Issues with our implementation can be worked around, but I'd 
rather clear this up regardless.

-- 
   -- Howard Chu
   Chief Architect, Symas Corp.       Director, Highland Sun
   http://www.symas.com               http://highlandsun.com/hyc
   Symas: Premier OpenSource Development and Support

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