[OpenAFS] OpenAFS 1.6.5/1.6.10 - server segfaults during migration to rxkad-k5

[Benjamin Kaduk]

On Fri, 7 Nov 2014, Benjamin Kaduk wrote:

> On Fri, 7 Nov 2014, Volkmar Glauche wrote:
>
> > mit-krb5# ktutil
> > ktutil:  rkt /etc/openafs/server/rxkad.keytab
> > ktutil:  l
> > slot KVNO Principal
> > ---- ----
> > ---------------------------------------------------------------------
> >    1    0 afs/cell@REALM
> >    2    0 afs/cell@REALM
> >    3    0 afs/cell@REALM
>
> kvno 0 is special in some ways; I would suggest trying with a different
> kvno.
> (That may not be the actual problem, but is the first thing I would try.)

Having looked more closely, I do believe it will fix the problem.

The NULL krb5_principal is passed to krb5_kt_get_entry() from
pick_enctype_and_principal(), which should already have picked a principal
by then, in pick_principal():

% pick_principal(krb5_context context, krb5_keytab kt,
%                krb5_principal *service_principal)
% {
%     krb5_error_code code;
%     krb5_kvno vno = 0;

initialized to zero

%     krb5_kt_cursor c;
%     krb5_keytab_entry n_entry;
%
%     /* Nothing to do */
%     if (*service_principal != NULL)
%         return 0;
%
%     memset(&n_entry, 0, sizeof(n_entry));
%
%     code = krb5_kt_start_seq_get(context, kt, &c);
%     if (code != 0)
%         goto cleanup;
%     while (code == 0 && krb5_kt_next_entry(context, kt, &n_entry, &c) == 0) {
%         if (n_entry.vno > vno) {

This check never succeeds.

%             vno = n_entry.vno;
%             (void)krb5_free_principal(context, *service_principal);
%             code = krb5_copy_principal(context, n_entry.principal,
%                                        service_principal);
%         }
%         (void)krb5_free_keytab_entry_contents(context, &n_entry);
%     }
%     if (code != 0) {
%         (void)krb5_kt_end_seq_get(context, kt, &c);
%         goto cleanup;
%     }
%     code = krb5_kt_end_seq_get(context, kt, &c);
%
% cleanup:

This should probably return an error if service_principal is not set here.

%     return code;
% }

-Ben