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From Ludovic Poitou <>
Subject Re: Fwd: Re: PasswordPolicy handling
Date Thu, 12 Mar 2015 09:27:59 GMT

more comments inline below…


Ludovic Poitou

From: Emmanuel Lécharny <>
Reply: Apache Directory Developers List <>>
Date: 12 Mar 2015 at 09:18:16
To: Apache Directory Developers List <>>
Subject:  Fwd: Re: PasswordPolicy handling  

Sorry, I posted my answer on the wrong mailing list. Here it is.  

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Le 11/03/15 11:43, Ludovic Poitou a écrit :  
> --  
> Ludovic Poitou  
> From: Emmanuel Lécharny <>  
> Reply: Apache Directory Developers List <>>  
> Date: 10 Mar 2015 at 09:23:04  
> To: Apache Directory Developers List <>>  
> Subject: PasswordPolicy handling  
> Hi guys,  
> this morning, we have had a quick discussion with Kiran that I will  
> retranscript here. Let me give you a bit of feedback first.  
> Yesterday, I was working on Studio, and more specifically on the  
> ApacheDS configuration PasswordPolicy page. I just wanted to add some  
> missing elements (a couple, pwdMinDelay and pwdMaxDelay). At some point,  
> I wondered how we could possibly associate a PP to an entry, assuming we  
> may define more than one PP, beside the default one.  
> Then I read the thread on the user list, where someone is having trouvle  
> defining a specific PP, and leverage it. The answer was to add a  
> pwdPolicySubEntry DN in each entry that has to use this added PP. Here  
> is an exemple :  
> dn: uid=jsmith,ou=users,ou=int,o=company  
> uid: jsmith  
> cn: jsmith  
> ...  
> pwdPolicySubEntry: ads-pwdId=internalUsers,ou=passwordPolicies,ads-interceptorId=authenticationInterceptor,ou=interceptors,adsdirectoryServiceId=default,ou=config
> The pwdPolicySubEntry attribute should be read-only, and thus should not be set by administrators.
> It should be set by the server to indicate which PP is enforced for a specific user.

This is my thought too. Sadly, this is not what we enforce atm.  
> No need to say that it's extremelly heavy when you have thousands of users.  
> I’ve yet to see a customer who wants to define a different password policy for each

That's not the use case. Our use case is different : sets of users using  
a different PP. As we only suport the automatic enforcement of the  
default PP, if one define a different PP, then each user's entry has to  
be updated to have the new PP's DN. Insane...  

I don’t think our use case is different.
We have customers that have different sets of users and want to enforce different password
policies for each set.
Typically is regular users, vs administrators vs application specific accounts.
I haven’t talked with any customer that wanted to push the limits to one user, one password
policy. This would be insane to manage (and stupid since there will be duplicated policies
In OpenDJ, the pwdPolicySubEntry attribute is an operational attribute that is computed and
points to the Policy that is enforced for the user. 

> Now, let me relate what we discussed with Kiran : 
> The RFC draft states that PP must be define in subentry : 
> "A password policy is defined for a particular subtree of the DIT by adding to an LDAP
subentry whose immediate superior is the root of the subtree" 
> By all means, it's equivalent to what we have for Collective Attributes, Subschema Subentries,
Access Control, Triggers. The DIT area impacted by such a subentry would be defined by the
subentry SubtreeSpecification, and each entry below the subentry's parent would be evaluated
accordingly to the SubtreeSpecification. The pwdPolicySubEntry attribute would be added on
the fly when the entry is requested, not added into the entry itself. 
> Exactly. 
> This would be a huge chenge is the way we currently handle PP, as we do it through the
cn=config partition. 
> My perception is that PP should not be stored in the configuration at all, but Kiran
perception is that would make it quite complicated to administrate the server, especially
when most of the users would have only one PP. 
> I agree with Kiran on this point. 
> Now, what are the possible path for a better handling of PPs ? Here are a few suggestions
> - the default PP should remain in the configuration. It will be associated with the rootDSE,
and apply to the whole DIT 
> - thid default PP could be disabled, if needed 
> - regarding new PP, we have two options : 
> - we keep declaring them in the confing, but they are translated to a subentry at startup
(we have to add a DN to the PP in config) 
> - we remove the PP declaration in the config 
> (I personally find the first approach more appealing, as it allows users to administrate
the config globally, although it makes it more complex from the code pov, as we have to update
teh config when we add a new PP as a subentry. That means the config generates a subentry,
and updating the subentry update the config. Not exactly simple...). 
> - we most certainly have to define a new administrative role for PP, and handle subentries
and teh way they are applied. That means we most certainly have to create a new interceptor 
> Lot of works, for sure. 
> Thoughts ? 
> OpenDJ supports both global PP that are defined as part of the configuration, and custom
password policies that are defined in the DIT as SubEntries, and assigned to specific users
directly, or through CollectiveAttributes. 
The option of mixing both model (ie, config + subentries) is available. 
I tend to think that a pure model (either every PP as subentries, or all 
of them in config) is probably easier to manage. 

Regarding CollectivAttributes, what the point using them to manage PPs ? 
The subentry mechanism applies to both class of roles, I'm not sure 
using CA to implement PP makes a lot of sense... In fact, that would 
introduce an indirection, where you will need to fetch the CA, and then 
fetch the associated PP to enforce the PP for each entry, instead of 
directly fetching the PP. Did I missed a step ? 

Collective attributes are allowing us to assign the global password policies, because we do
not translate them to a proper subentry with a global scope.

It also allows to have different sub-scopes pointing to a same policy. (think about an ISP
that has 20 organizations, and in each, different sets of users that must have the same “Administrators”
password policy. With just the subentry mechanism, adding a new organisation means that you
must update the subEntry and impact all users.

With a collectiveAttribute, it can be defined in the new organisation and have no impact on
the other ones.

> We have a specific operational attribute that one can set to assign a password policy
to a user (ds-pwp-password-policy-dn). 

This somehow contradict what you wrote upper (the attribute is read 
only, administrators should not be able to change the attribute) ? Or is 
it for each user to define its own PP (which I find to be a security 
breah, somehow). 
It does not contradict. It complements. We have 2 separate attributes. One to assign if needed
(i.e. overwrite the global policy), which can be done with CollectiveAttributes, or directly
in the user entry, and one that is read only and points to the enforced policy.

This attribute is protected by ACI, and it doesn’t define the Password Policy, it refer
to an existing policy. No security concern here.

> The advantage of the custom password policies part of the DIT is that they are replicated
and thus are guaranteed to be identical on all servers. 
The config is very likely to be replicated too. Having the PP definition 
in the config does not impede the replication to be done, even if the 
config is not replicated : it's just a matter to be careful in the way 
we replicate subentries. 

We do not replicate the config.

> In general, most customers define 1 or 2 policies. 
> For your proposal, I think it makes sense to translate the PP defined in the config into
a subEntry, that is read-only. 

Which will probably what we are going to do, except that the subentry 
will not hold the full config, but just a copy of it. 

Thanks Ludo ! 

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