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

[Aurélien Aptel]

Chad William Seys via samba <samba at lists.samba.org> writes:
>    But when cifs-utils 6.4-1 is installed (from jessie) the different
> user can access as expect.  AFAIK there are no other differences besides
> the cifs-utils version.

Not counting any distro-specific patches it seems cifs.upcall only had 5
commits affecting it between these 2 releases:

  $ git log  --pretty=oneline cifs-utils-6.6...cifs-utils-6.4 cifs.upcall.c
  7852bec cifs.upcall: stop passing around ccache name strings
  39dbb7b cifs.upcall: make get_tgt_time take a ccache arg
  3db6b3a cifs.upcall: remove KRB5_TC_OPENCLOSE
  a3743af cifs.upcall: make the krb5_context a static global variable
  9be6e88 cifs.upcall: use krb5 routines to get default ccname

It seems the way cached credentials are searched changed, which your logs
show if you diff them:

  uid=0
  creduid=0
  user=smbadmin at PHYSICS.WISC.EDU
 -pid=27600
 -find_krb5_cc: scandir error on directory '/run/user/0': No such file or directory
 -find_krb5_cc: considering /tmp/krb5cc_0
 -find_krb5_cc: FILE:/tmp/krb5cc_0 is valid ccache
 -find_krb5_cc: considering /tmp/krb5cc_1494_sM11PG
 -find_krb5_cc: /tmp/krb5cc_1494_sM11PG is owned by 1494, not 0
 +pid=26578
 +get_tgt_time: unable to get principal
  handle_krb5_mech: getting service ticket for smb.physics.wisc.edu
  handle_krb5_mech: obtained service ticket
  Exit status 0

That "get_tgt_time: unable to get principal" message looks like it could
be related to "39dbb7b cifs.upcall: make get_tgt_time take a ccache
arg". Since you can easily reproduce the problem, if I were you I would
try to find the bad commits between those 5.

-- 
Aurélien Aptel / SUSE Labs Samba Team
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