mit-krb5 and heimdal binaries

[Rowland Penny]

On 19/03/2023 07:29, Alexander Bokovoy via samba-technical wrote:
> Hi,
> 
> On su, 19 maalis 2023, Michael Tokarev via samba-technical wrote:
>> Hi!
>>
>> I already asked a similar question before, but it keeps popping up in different
>> contexts and forms, and the more I use samba myself, the more often it comes to
>> me too, especially in context of using various security tokens for auth.  And the
>> more I think about all this, the more sane it looks to me.
>>
>> The thing is: mit-krb5 has much better user-level support than heimdal. But samba
>> does not fully support mit-krb5 as an active directory domain controller.  The
>> AD-DC thing is server-side.
>>
>> I can think of providing two builds of samba for a distribution (eg debian/ubuntu), -
>> one implementing whole ad-dc, as a complete thing, using their own set of libs,
>> linked with heimdal. And a usual set of more client-side packages, with their own
>> libraries, built against mit-krb5.  Or maybe some other combination also has its
>> right to be, - for example, smbclient built with mit-krb5, the rest is heimdal.
>>
>> An essential part of this is that the two sets (built against mit-krb5 and heimdal)
>> do not share any internal libraries, each has its own libraries. This way, there's
>> no "mix" of differently built samba, each build uses only its own libs, so there's
>> no clash here.  They share the same smb.conf though.
>>
>> So far, I've seen requests to build two versions of the server (again, with mit-krb5
>> and with heimdal), - and I faced the same issues too.  This is because a regular AD
>> member server is also good to have mit-krb5 support to integrate nicely into the auth
>> infrastructure. While for ad-dc, it is less often used as "end-user" server.
>>
>> So I can think of a separate samba-ad-dc binary package providing whole samba suite
>> built against heimdal (maybe without smbclient and some other minor things), and
>> samba "file server" binary package providing regular server not suitable to use as
>> an ad-dc, but conflicting with samba-ad-dc, so it is not possible to install one
>> together with another.
>>
>> This approach also has another good side effect, to discourage usage of samba-ad-dc
>> as a regular file server.
>>
>> Or maybe the whole thing is moot now, and we just can provide regular samba built
>> against mit-krb5 to work as a good AD-DC?  That would be the best solution IMHO.
> 
> I would be against a blended build against both MIT Kerberos and Heimdal
> Kerberos in a distribution. It is not going to bring you anything good,
> support wise.
> 
> Andreas and I have submitted a talk to SambaXP about MIT
> Kerberos/Heimdal Kerberos-based Samba AD DC configurations, where they
> stand against each other and what are perspectives. In short, both have
> unique features that do not exist in the other variant and both are
> close to being production-ready. We want to change the status for MIT
> Kerberos-based build from experimental to production. Effectively,
> actual decision for a version shipped in a particular distribution would
> need to be made by that distribution, of course.

I do not think this is a good idea, Samba should use one or the other, 
not both. If you do use both, to a certain extent you will nearly double 
the support required.

> 
> Distributions need to take into account security releases, as Rowland
> has pointed out as well. However, from my Fedora and RHEL experience,
> this is not a problem with MIT Kerberos -- certainly not more than with
> Heimdal. It is pretty much a coordination question and I believe we have
> very good coordination on that front with MIT Kerberos and distribution
> maintainers.

That is strange, from what Andrew wrote, he appears to think the opposite.

> 
> If I was in Samba AD support for production deployments, I'd probably
> go with deploying DCs in a containerized image way to isolate completely
> from the rest of the OS. There are few images already that provide this
> setup: [1] was presented at SambaXP by Michael Adam and other folks now
> from IBM Storage, [2] is older and also active one.
> 
> [1] https://github.com/samba-in-kubernetes/samba-container
> [2] https://github.com/instantlinux/docker-tools/tree/main/images/samba-dc
> 

I personally have no axe to grind over the matter, I do not care which 
kdc is used, just as long as it is only one, if only from the support 
point of view.
I also only say that using MIT is experimental because other wiser (at 
least I hope they are wiser than me) people say it is, if this changes 
then so be it.

I still do not think it is a good idea for a distro to provide two 
versions of Samba, one using Heimdal and the other using MIT.

Rowland