The documentation is insufficient to use cifs.upcall

[Karl O. Pinc]

It is not clear how to get k4b5 credential cache file name information to cifs.upcall.

The documentation says that cifs.upcall can get the ccname from the $KRB5CCNAME environment variable. But it is not at all clear how to set this environment variable to the correct value, particularly when systemd.automount(5) is used to mount.

Further, as of this writing, in order to use many cifs.upcall features the default krb5 ccname must be changed. This is not documented.

(And I don't know if this is the right place to report this, but the current krb5 DEFCCNAME seems to end with an _ followed by some sort of hash. There does not seem to be a documented krb5 parameter that expands to such a hash. Wouldn't such a thing be necessary in order to properly generate the right ccname?)

See also: bug #2012140 bug #2012143 bug #2012145

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: cifs-utils 2:6.14-1ubuntu0.1
ProcVersionSignature: Ubuntu 5.15.0-67.74-generic 5.15.85
Uname: Linux 5.15.0-67-generic x86_64
ApportVersion: 2.20.11-0ubuntu82.3
Architecture: amd64
CasperMD5CheckResult: pass
Date: Sat Mar 18 18:14:52 2023
InstallationDate: Installed on 2023-03-09 (9 days ago)
InstallationMedia: Ubuntu-Server 22.04.2 LTS "Jammy Jellyfish" - Release amd64 (20230217.1)
ProcEnviron:
 SHELL=/bin/bash
 LANG=en_US.UTF-8
 TERM=xterm-256color
 PATH=(custom, no user)
SourcePackage: cifs-utils
UpgradeStatus: No upgrade log present (probably fresh install)