/etc/apparmor.d/abstractions/authentication is in apparmor 2.7.102-0ubuntu3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 | # ------------------------------------------------------------------
#
#    Copyright (C) 2002-2009 Novell/SUSE
#    Copyright (C) 2009-2012 Canonical Ltd
#
#    This program is free software; you can redistribute it and/or
#    modify it under the terms of version 2 of the GNU General Public
#    License published by the Free Software Foundation.
#
# ------------------------------------------------------------------
  # Some services need to perform authentication of users
  # Such authentication almost certainly needs access to the local users
  # databases containing passwords, PAM configuration files, PAM libraries
  /etc/nologin                r,
  /etc/pam.d/*                r,
  /etc/securetty              r,
  /etc/security/*             r,
  /etc/shadow                 r,
  /etc/gshadow                r,
  /etc/pwdb.conf              r,
  /lib{,32,64}/security/pam_filter/*  mr,
  /lib{,32,64}/security/pam_*.so      mr,
  /lib{,32,64}/security/              r,
  /lib/@{multiarch}/security/pam_filter/*  mr,
  /lib/@{multiarch}/security/pam_*.so      mr,
  /lib/@{multiarch}/security/              r,
  # kerberos
  #include <abstractions/kerberosclient>
  # SuSE's pwdutils are different:
  /etc/default/passwd         r,
  /etc/login.defs             r,
  # nis
  #include <abstractions/nis>
  # winbind
  #include <abstractions/winbind>
  # likewise
  #include <abstractions/likewise>
  # smbpass
  #include <abstractions/smbpass>
  # p11-kit (PKCS#11 modules configuration)
  #include <abstractions/p11-kit>
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