Re: heimdal -> MIT kdc migration

On Fri, Aug 29, 2025 at 7:43 AM Rick Macklem <rick.macklem@gmail.com> wrote:
>
> On Wed, Aug 27, 2025 at 8:39 PM Rick Macklem <rick.macklem@gmail.com> wrote:
> >
> > On Wed, Aug 27, 2025 at 7:43 PM Rick Macklem <rick.macklem@gmail.com> wrote:
> > >
> > > On Tue, Aug 26, 2025 at 9:35 AM Gleb Smirnoff <glebius@freebsd.org> wrote:
> > > >
> > > > On Tue, Aug 26, 2025 at 08:31:13AM -0700, Gleb Smirnoff wrote:
> > > > T> On Tue, Aug 26, 2025 at 08:13:26AM -0700, Rick Macklem wrote:
> > > > T> R> Ok. If you install FreeBSD-13.5 and then "pkg install heimdal", you get a
> > > > T> R> working Heimdal-7.8 in ports.
> > > > T> R>
> > > > T> R> Now, I have another challenge. Fixing the master passwords.
> > > > T> R> I'll work on it later to-day.
> > > > T>
> > > > T> I have applied two commits from Heimdal from 2012 that add 'kadmin dump -f MIT'
> > > > T> feature to our base heimdal and polished them to compile.  So far it doesn't
> > > > T> work yet, either create an empty dump or create a core dump, instead of
> > > > T> database dump :) I'll see how difficult it is going to further resolve that to
> > > > T> a working condition. If I succeed, then having 'dump -f MIT' in base without
> > > > T> any ports would be the best solution.  Can also be merged to FreeBSD 14.4.
> > > >
> > > > Good news.  In the above paragraph I was testing my change incorrectly - threw
> > > > the new binary on a system running unpatched libraries.  When run correctly,
> > > > it successfully produced something that looks like a correct dump in MIT format.
> > > > I haven't yet tried to load it into MIT kdc yet, though.
> > Oh, and one more thing...
> > - If there are keys for old encryption types like des.. or arcfour..
> > in the MIT dump,
> >   those will screw up the load. (You can check and delete them in the
> > Heimdal-1.5.2
> >   kdc system via..
> >   # kadmin -l
> >   get <principal>
> >   - if old keys are listed in Keytypes:
> >   del_enctype <principal> <enctypes>
> >  exit
> >
> >  Ideally the conversion code would skip over these and not put them in the dump.
> >
> > rick
> > ps: If you don't do this, when you "get_principal" in kadmin.local on
> > the MIT KDC
> >       system, it will give you a "Database record is incomplete or corrupted..".
> >
> > > >
> > > > I will finalize the branch promptly and share it.  The above experience also
> > > > indicated that I need to do a library version bump.
> > > I don't know if you are enthusiastic about pursuing this, but hopefully this
> > > works and gets the principals in (although I doubt the passwords will
> > > work without changing them).
> > >
> > > To get the passwords to work, I think the following *might* do it:
> > > - If you look in the Heimdal sources, when "--decrypt" is specified,
> > >   I think it finds its way down into a function called hdb_unseal_key_mkey()
> > >   which decrypts the key using the master key by calling _hdb_mkey_decrypt().
> > >   To get the passwords to work, I think the call to _hdb_mkey_decrypt() would
> > >   need to be followed by a call to _hdb_mkey_encrypt() with the "key"
> > >   argument being the master key for the MIT database. (It it a keytab
> > >   entry called /var/db/krb5kdc/.k5.YOUR.REALM created when you do a
> > >   "kdb5_util create -s" on the system that will be the MIT KDC.)
> > >   - Just to make it even more fun, there is a flag called HDB_KU_MKEY
> > >     which is set to the Heimdal way and not for the MIT way (whatever
> > >     that really means?).
> > >   - There is also some stuff about padding in hdb_unseal_key_mkey(),
> > >     but hopefully that won't be a problem?
> > >
> > > I think hdb_read_master_key() can be used to read in the MIT master
> > > key from the file you provide as an argument to it.
> > >
> > > This all is just a hunch, based on what I've seen so far.
> > >
> > > I'll admit since the hardware I have takes forever to "make buildworld"
> > > and I don't know a quick way to build/test these changes, I'm not
> > > inspired to try it.
> Although not inspired, I have taken a stab at it.
> I am still trying to figure out how to build/test it, but I have forked
> glebius@'s github and added some code to...
> - Not dump the weak encryption keys (they just cause MIT's kadmin.local
>   to complain that the principal's database entry is corrupted.
> - If the argument to "kadmin -l dump" is "-f <mit-master-key-file>" instead
>   of "-f MIT" it re-encrypts the keys in MIT's master key. (I hope that will
>   make the passwords work.
>   (Basically, someone will "kdb5_util create -s" on the MIT KDC system
>    and then copy the /var/db/krbkdc/.k5.YOUR.REALM file over to the
>    Heimdal KDC system and do "kadmin -l dump -f <.k5-filename> mit.dump"
>    then copy "mit.dump" over to the MIT KDC system and
>    "kdb5_util load -update mit.dump". Then, hopefully, the principals will
>    work??)
>
> Anyhow, it is currently sitting here:
> github.com/rmacklem/FreeBSD in the kadmin-dump-MIT branch.
> (I'm as unconversant with git and github as anyone, so if you have
> trouble finding it, just let me know.)
Actually, it hasn't made it there yet. For some reason (I think it is
glebius@s large # of branches) it takes a very long time to "git push"
a patch involving 4 files. It failed after over an hour with an unexpected
TCP disconnect. I am running it again.

I will stick the patch here, in case the push fails again.
(It needs to be applied on top of glebius@'s kadmin-dump-MIT branch.
https://people.freebsd.org/~rmacklem/kadmin.patch

Meanwhile I've given up trying to build it on a universe system and
an now trying the "make buildworld" locally. This will take days,
so I guess I'll go do something else.;-)

rick

>
> I'll keep updating this github fork as I get to test it, but if others
> know how to build it, feel free to test, rick
>
> > >
> > > rick
> > >
> > > >
> > > > --
> > > > Gleb Smirnoff