[PATCH] cifs: eliminate CONFIG_CIFS_WEAK_PW_HASH

Jeff Layton jlayton at redhat.com
Fri Apr 27 09:14:51 MDT 2012


On Fri, 27 Apr 2012 08:58:55 -0500
Steve French <smfrench at gmail.com> wrote:

> On Fri, Apr 27, 2012 at 6:15 AM, Jeff Layton <jlayton at redhat.com> wrote:
> > On Sat, 21 Jan 2012 12:26:43 -0500
> > simo <idra at samba.org> wrote:
> >
> >> On Sat, 2012-01-21 at 07:37 -0500, Jeff Layton wrote:
> >> > On Sat, 21 Jan 2012 15:03:31 +1100
> >> > Andrew Bartlett <abartlet at samba.org> wrote:
> >> >
> >> > > On Fri, 2012-01-20 at 14:45 -0600, Steve French wrote:
> >> > > > My general thinking on this is as follows:
> >> > > >
> >> > > > If the kernel is distributed to all the workstations in an organization
> >> > > > with this Kconfig option disabled, it makes it harder for individual users
> >> > > > to make the mistake of enabling lanman (sec=lanman, or the Kconfig
> >> > > > option) on a public network and thus send weak password hashes
> >> > > > which could be discovered simply.   Most distros make the choice
> >> > > > of enabling broader compatibility with old pre-1997 servers but
> >> > > > it is a very small set of servers who would require lanman support,
> >> > > > and a large number of potential attackers who could benefit if
> >> > > > users enable lanman on a public network.  I suspect that there
> >> > > > are environments where removing code (via Kconfig) is preferred
> >> > > > to trusting all owners of all workstations running that organizations
> >> > > > standard linux to never enable lanman at runtime.
> >> > > >
> >> > > > But ... the opinion of security specialists on this would be welcome.
> >> > >
> >> > > We have been though some of this with the kerberos libs, which now allow
> >> > > (default?) to not even compile with weak crypto.  If the weak crypto is
> >> > > not compiled in, it can therefore be asserted that the weak crypto
> >> > > cannot be used, and this makes it easier to comply with security
> >> > > audits/certification etc.
> >> > >
> >> > > I don't want to make your code more complex than it needs to be, but LM
> >> > > encryption really, really needs to go away.  If it is not a major
> >> > > bother, I would like to make it easier for that to happen if possible.
> >> > >
> >> >
> >> > The only way for it to go away completely is for all servers that
> >> > support only that encryption to go away completely. Unfortunately,
> >> > that's a tall order -- there are still at least some in the field and
> >> > people need to get at data on them.
> >>
> >> Jeff, can you identify them ?
> >>
> >> LM only servers means pre Win 95 machines, I'd be curious to know what
> >> servers are there that really support only LM hashes and not NT hashes.
> >>
> >
> > Sorry for the long delay in responding here. Yes, mostly pre-win95
> > machines. We occasionally get reports from people using OS/2 and I'm
> > pretty sure it's LM-only.
> >
> > Steve, in any case...shall I consider this patch NAK'ed for now? I was
> > carrying it in my tree for 3.5, but it seems like there's resistance to
> > removing this option and I'm not particularly religious on the matter.
> 
> I don't think it is worth changing - I prefer to build with
> WEAK_PS_HASH disabled.
> 

Alrighty then, dropped...

-- 
Jeff Layton <jlayton at redhat.com>


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