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

[Simo Sorce]

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.

-- 
Simo Sorce * Red Hat, Inc * New York