[Pkg-samba-maint] Bug#1100776: cifs.upcall program in the cifs-utils package fails to use a valid service ticket from the credential cache if the TGT is expired or not exist

[Bharath SM]

Package: cifs-utils
Version: 7.1


Issue: cifs.upcall program in the cifs-utils package fails to use a
valid service ticket from the credential cache if the TGT is expired
or not exist

Description:
When mounting an SMB file share on Linux using the kernel client with
Kerberos authentication, the Linux kernel's cifs.ko module makes an
upcall to user space during the session setup phase to retrieve the
Kerberos service ticket from the credential cache. However, the
current cifs.upcall fails to retrieve the service ticket even if it is
valid, but instead it makes a check to TGT to see if its valid and
then retrieve the service ticket, but if we already have valid service
ticket we shouldn't need to check for TGT.
i.e In cases where the kernel handles upcalls for SMB session setup
requests with Kerberos authentication, if the credential cache already
contains a valid service ticket, it should be used directly without
needing to check the TGT again.

Fixed commit: https://git.samba.org/?p=cifs-utils.git;a=commit;h=af76bf2a11a060afdfd97104617a701d19d5890d

Please review and help backporting this commit to existing debian
distro cifs-utils.