[Freeipa-devel] [PATCH 0026] Prevent integer overflow when setting krbPasswordExpiration

[Tomas Babej]

On 01/15/2013 11:55 PM, Simo Sorce wrote:
> On Tue, 2013-01-15 at 17:36 -0500, Dmitri Pal wrote:
>> On 01/15/2013 03:59 PM, Simo Sorce wrote:
>>> On Tue, 2013-01-15 at 15:53 -0500, Rob Crittenden wrote:
>>>> Dmitri Pal wrote:
>>>>> On 01/15/2013 08:48 AM, Simo Sorce wrote:
>>>>>> On Mon, 2013-01-14 at 16:46 +0100, Tomas Babej wrote:
>>>>>>> Hi,
>>>>>>>
>>>>>>> Since in Kerberos V5 are used 32-bit unix timestamps, setting
>>>>>>> maxlife in pwpolicy to values such as 9999 days would cause
>>>>>>> integer overflow in krbPasswordExpiration attribute.
>>>>>>>
>>>>>>> This would result into unpredictable behaviour such as users
>>>>>>> not being able to log in after password expiration if password
>>>>>>> policy was changed (#3114) or new users not being able to log
>>>>>>> in at all (#3312).
>>>>>>>
>>>>>>> https://fedorahosted.org/freeipa/ticket/3312
>>>>>>> https://fedorahosted.org/freeipa/ticket/3114
>>>>>> Given that we control the KDC LDAP driver I think we should not limit
>>>>>> the time in LDAP but rather 'fix-it-up' for the KDC in the DAL driver.
>>>>> Fix how? Truncate to max in the driver itself if it was entered beyond max?
>>>>> Shouldn't we also prevent entering the invalid value into the attribute?
>>>>>
>>>> I've been mulling the same question for a while. Why would we want to
>>>> let bad data get into the directory?
>>> It is not bad data and the attribute holds a Generalize time date.
>>>
>>> The data is valid it's the MIT code that has a limitation in parsing it.
>>>
>>> Greg tells me he plans supporting additional time by using the
>>> 'negative' part of the integer to represent the years beyond 2038.
>>>
>>> So we should represent data in the directory correctly, which means
>>> whtever date in the future and only chop it when feeding MIT libraries
>>> until they support the additional range at which time we will change and
>>> chop further in the future (around 2067 or so).
>>>
>>> If we chopped early in the directory we'd not be able to properly
>>> represent/change rapresentation later when MIT libs gain additional
>>> range capabilities.
>>>
>>> Simo.
>>>
>> We would have to change our code either way and the amount of change
>> will be similar so does it really matter?
> Yes it really matters IMO.
>
> Simo.
>
Updated patch attached.

Tomas
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