[Freeipa-devel] Patch for #1539

[Martin Kosek]

On 06/06/2014 05:47 PM, Nathaniel McCallum wrote:
> On Fri, 2014-06-06 at 11:43 -0400, Simo Sorce wrote:
>> On Fri, 2014-06-06 at 11:06 -0400, Nathaniel McCallum wrote:
>>> On Fri, 2014-06-06 at 08:00 -0400, Simo Sorce wrote:
>>>> On Fri, 2014-06-06 at 10:30 +0200, Martin Kosek wrote:
>>>>> On 05/31/2014 03:27 AM, Simo Sorce wrote:
>>>>>> I have rebased theold patch attached to the ticket, unfortunately I
>>>>>> haven't had time to test it yet, but didn't want to lose it in some
>>>>>> branch.
>>>>>>
>>>>>> Simo.
>>>>>
>>>>> I tested the patch and it worked fine, code also reads OK. Thus, I am willing
>>>>> to ACK it.
>>>>>
>>>>> I am just wondering if there is any scenario we could have missed, but I did
>>>>> not find any. In there is no push back against the patch I may just push it.
>>>
>>>> The only thing I would draw attention to is the fact that now I am
>>>> sending back the error directly once we have a negative return from the
>>>> function in which expiration is checked (ipapwd_authenticate).
>>>>
>>>> I could not see why we did, in fact, not do that before and I meant
>>>> asking Nathaniel if he had an explicit reason why we do not, as he is
>>>> the last one that did some significant refactoring in the bind preop
>>>> plugin.
>>>
>>> In the current design, if ipapwd_authenticate() fails, we defer to 389ds
>>> for the actual response to the client. The purpose for this is so that
>>> verification of the first factor always behaves the same, regardless of
>>> what is in pre-bind.
>>>
>>> So ipapwd_authenticate() is not actually the "final" authentication. It
>>> is a preliminary authentication to determine if the user should be able
>>> to write kerberos keys and perform OTP sync. So checking expiration in
>>> pre-bind only protects these two operations.
>>>
>>> I presume that 389ds also checks password expiration. If this assumption
>>> is true, ipapwd_authenticate() SHOULD NOT return any response to the
>>> client. It should simply fail key-write/otp-sync silently and let dirsrv
>>> return the error to the client.
>>
>> 389ds would check it if we were using 389ds native password policies but
>> we are not. So we need to check on our own, which is what this patch
>> implements.
>>
>>> The important point here is that so long as 389ds is verifying password
>>> expiration, using a correct-but-expired password will should not result
>>> in a bind in the current code. It will result in kerberos key writing
>>> and OTP sync. Do we actually care about protecting kerberos key writing
>>> and OTP sync from correct-but-expired passwords?
>>
>> No, but that's not the point.
>>
>>> If 389ds does not check password expiration, then we probably need to
>>> patch upstream 389ds or, at the very least, return an error to the
>>> client.
>>
>> It is not a 389ds bug, it is just an integration issue due to the fact
>> IPA uses a different schema for password policies (for compatibility
>> with the Kerberos schema).
>>
>>> Otherwise, if we don't care about protecting kerberos key writing and
>>> OTP sync from correct-but-expired passwords, this patch is entirely
>>> unnecessary.
>>>
>>> Otherwise, the patch is necessary, but should skip kerberos key writing
>>> and OTP sync and fall through silently to 389ds.
>>
>> If we fall through to 389ds then authentication will succeed.
>>
>> So from this discussion it seem to me we achieve the goal of the patch
>> and returning an error directly is ok.
>>
>> Unless Nathaniel has something *against* returning an error in this
>> place I think we are good to go.
> 
> Looks good to me. ACK.
> 
> Nathaniel
> 

Ok, thanks for discussion and double checking!

Pushed to master: bfdbd3b6ad7c437e7dd293d2488b2d53f4ea7ba6

Martin