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

[Tomas Babej]

On 01/16/2013 02:47 PM, Simo Sorce wrote:
> On Wed, 2013-01-16 at 12:52 +0100, Tomas Babej wrote:
>> 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.
> This part looks ok but I think you also need to properly set
> krb5_db_entry-> {expiration, pw_expiration, last_success, last_failed}
> in ipadb_parse_ldap_entry()
>
> Perhaps the best way is to introduce a new function
> ipadb_ldap_attr_to_krb5_timestamp() in ipa_kdb_common.c so that you do
> all the overflow checkings once.
>
> Simo.
>
They all use ipadb_ldap_attr_to_time_t() to get their values,
so the following addition to the patch should be sufficient.

Tomas
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