** Description changed: [ 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 ] * Any production systems that use lastlog in a `required` manner may be broken by this change, if they are not already in a broken state. This SRU doesn't remove the lastlog binary, just the requirement for tty login. I believe the impact would be minimal. [ 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
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2060676 Title: [SRU] login: remove pam_lastlog.so from config To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/shadow/+bug/2060676/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
