[Samba] cifs-utils: regression in (mulituser?) mounting 'CIFS VFS: Send error in SessSetup = -126'

[Chad William Seys]

Hi Jeff,
Could you look at the following mailing list posting?

https://lists.samba.org/archive/samba/2017-February/206468.html

It looks like cifs.upcall has changed its behavior.  As described in 
that post, I can mount with root / kerberos, but then cannot access with 
another user who has credentials.

The logs indicate that cifs.upcall cannot find the kerberos ticket for 
the non-root user.

This problem does not exist in cifs-utils 6.5 and does exist in 6.6 .

My best guess ATM is that the below commit caused the problem.

Thanks for your time!
Chad.

commit 9be6e885c3bd63aa6ae9e6351e1b33a4b15d9183
Author: Jeff Layton <jlayton at samba.org>
Date:   Sun Aug 21 09:42:59 2016 -0400

     cifs.upcall: use krb5 routines to get default ccname
     Currently we end up groveling around in /tmp, trying to guess what 
the credcache will be. Instead, just get the default ccname for the 
user, and then see if it has a valid tgt. If it doesn't then we try to 
use the keytab to init the credcache before proceeding.