[Bug 2060676] Re: [SRU] login: remove pam_lastlog.so from config

Fri Nov 29 17:41:16 UTC 2024

Hello Alfonso, or anyone else affected,

Accepted shadow into noble-proposed. The package will build now and be
available at
https://launchpad.net/ubuntu/+source/shadow/1:4.13+dfsg1-4ubuntu3.3 in a
few hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested, what testing has been
performed on the package and change the tag from verification-needed-
noble to verification-done-noble. If it does not fix the bug for you,
please add a comment stating that, and change the tag to verification-
failed-noble. In either case, without details of your testing we will
not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: shadow (Ubuntu Noble)
       Status: In Progress => Fix Committed

** Tags added: verification-needed verification-needed-noble

-- 
You received this bug notification because you are a member of Ubuntu
Sponsors, which is subscribed to the bug report.
https://bugs.launchpad.net/bugs/2060676

Title:
  [SRU] login: remove pam_lastlog.so from config

Status in shadow package in Ubuntu:
  Fix Released
Status in shadow source package in Noble:
  Fix Committed
Status in shadow source package in Oracular:
  Fix Released
Status in shadow package in Debian:
  Fix Released

Bug description:
  [ Impact ]

   * The following line has been found in users logs when trying to log in to their systems:
     login[2449]: PAM unable to dlopen(pam_lastlog.so): /usr/lib/security/pam_lastlog.so: cannot open shared object file: No such file or directory
     This is the only known occurrence of the log. It occurs when users log in to their systems using a tty, or rather referred to as the 'login' method in shadow/pam etc. This log error message is not present when logging in via ssh, gdm, xdm, or other login methods, as they do not depend on the lastlog binary.

   * The upload fixes the issue by dropping pam_lastlog.so from all
  config, as well as not installing the lastlog binary.

  [ Test Plan ]

  ```
  wget https://releases.ubuntu.com/noble/ubuntu-24.04.1-desktop-amd64.iso
  qemu-system-x86_64 -boot d -cdrom /path/to/ubuntu-24.04.1-desktop-amd64.iso -m 8192M -smp 2 -hda /tmp/yarf-vm.qcow2 -enable-kvm -device qxl
  # install the system, and reboot
  # at the login screen post-reboot, press ctrl+alt+f2
  # login via tty
  journalctl -b 0 --no-pager | grep pam_lastlog.so
  # and you will see the error message
  sudo sed '/session    optional     pam_lastlog.so/d' /etc/pam.d/login
  # logout
  # log back in via tty
  journalctl  # check the logs since you logged in, you will not see any mention of pam_lastlog.so
  ```

   * In order to test this after the fix lands in noble proposed, do the
  same as above, except instead of manuall removing the entry from
  /etc/pam.d/login, install the version of shadow from proposed, and
  assert that the log messages are no longer present.

  [ Where problems could occur ]

   * It seems extremely improbable anyone would configure login.pam to
  explicitly *require* pam_lastlog.so, I also can't imagine anyone would
  create any functionality that'd explicitly *depend* on pam_lastlog.so
  being *required*.

  [ Other Info ]

   * the pam_lastlog.so binary was dropped in shadow/1:4.13+dfsg1-5.
  Included in this change also is dropping pam_lastlog.so from
  debian/login.pam.

   * The version of shadow in oracular is 1:4.15.3-3ubuntu2, and thus
  this error message isn't present in oracular onwards.

   * We absolutely *cannot* re-introduce pam_lastlog.so as it was
  dropped as part of the time_t transition, see commit:
  https://github.com/linux-pam/linux-
  pam/commit/357a4ddbe9b4b10ebd805d2af3e32f3ead5b8816

   * pam_lastlog2 is depended upon in util-linux after version 2.40-7.
  We can make changes in shadow going forward that depends on
  pam_lastlog2 rather than pam_lastlog. But that's not really relevant
  to the SRU I guess. These changes are planned to be implemented
  upstream https://bugs.debian.org/cgi-
  bin/bugreport.cgi?att=0;bug=1068229;msg=39, so likely from Ubuntu's
  side, we can just wait for the changes.

   * However, upstream, shadow still doesn't have any mention of
  lastlog2 in debian/login.pam. So we can't SRU a change to depend on
  this new lastlog binary, as it's not in devel yet.

   * We could, however, SRU a change wherein we revert the dropping of
  pam_lastlog.so in shadow, but this is more involved and would likely
  be a separate SRU, wherein either that SRU or this one lands.

  [Original description]

  Imported from Debian bug http://bugs.debian.org/1068229:

  Package: libpam-modules
  Version: 1.5.3-6
  Severity: normal

  I noticed the following line in my logs:

  login[2449]: PAM unable to dlopen(pam_lastlog.so):
  /usr/lib/security/pam_lastlog.so: cannot open shared object file: No
  such file or directory

  I looked in the deb files from snapshot.debian.org, and noticed the last version
  that had it was 1.5.2-9.1 - starting from 1.5.3-1 it disappeared.

  Maybe it's fallout from the time_t transition and you're already aware of it, in
  which case feel free to close.

  Thanks,

  -- M

  -- System Information:
  Debian Release: trixie/sid
    APT prefers unstable
    APT policy: (500, 'unstable'), (1, 'experimental')
  Architecture: amd64 (x86_64)
  Foreign Architectures: i386, arm64

  Kernel: Linux 6.7.9-amd64 (SMP w/4 CPU threads; PREEMPT)
  Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE
  Locale: LANG=C.UTF-8, LC_CTYPE=C.UTF-8 (charmap=UTF-8), LANGUAGE not set
  Shell: /bin/sh linked to /usr/bin/dash
  Init: systemd (via /run/systemd/system)

  Versions of packages libpam-modules depends on:
  ii  debconf [debconf-2.0]  1.5.86
  ii  libaudit1              1:3.1.2-2.1
  ii  libc6                  2.37-15.1
  ii  libcrypt1              1:4.4.36-4
  ii  libpam-modules-bin     1.5.3-6
  ii  libpam0g               1.5.3-6
  ii  libselinux1            3.5-2
  ii  libsystemd0            255.4-1+b1

  libpam-modules recommends no packages.

  libpam-modules suggests no packages.

  -- debconf information excluded

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/shadow/+bug/2060676/+subscriptions