[Bug 2012143] Re: cifs.upcall does not use the kerberos default credential cache file, so many features fail

[Karl O. Pinc]

This bug, and the "see also" bugs mentioned above, have existed since at
least Ubuntu 18.

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https://bugs.launchpad.net/bugs/2012143

Title:
  cifs.upcall does not use the kerberos default credential cache file,
  so many features fail

Status in cifs-utils package in Ubuntu:
  New

Bug description:
  cifs.upcall does not use the default kerberos credential cache file
  name.  Attempting to make smb3 mounts in /etc/fstab with
  username=...,cruid=...,domain=...,sec=krb5,multiuser,_netdev,x-systemd.automount
  fail, with messages in the journalctl logs like:

  ...krb5_child[4725]: No credentials cache found (filename:
  /tmp/krb5cc_127408622_wH2NwY

  This can be worked-around by adding:

  [libdefaults]
  # Use the same cache path as cifs.upcall
  # Supposedly the value we set is the default, but there seems to be
  # an additional underscore and then a 4 character hash unless
  # this is set.  The result, unless we set this param, is that
  # cifs.upcall cannot get the kerberos ticket-granting-ticket.
  # This is only visible in the journalctrl logs.
  	default_ccache_name = FILE:/tmp/krb5cc_%{euid}

  to /etc/krb5.conf.  I believe a reboot is required.

  This is with user accounts authenticated against MS Active Directory.  (Which
  uses kerberos).

  Without the workaround the user accounts do not authenticate, so per-
  user mounts are not possible.

  See also Ubuntu bug #2012140
  https://bugs.launchpad.net/ubuntu/+source/krb5/+bug/2012140

  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 17:43:19 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)

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