lightdm assumes pam-kwallet to be always installed

[Saverio Miroddi]

During boot, I see this error:

> Feb 02 10:50:05 myhost lightdm[3224]: PAM unable to dlopen(pam_kwallet.so): /lib/security/pam_kwallet.so: cannot open shared object file: No such file or directory
> Feb 02 10:50:05 myhost lightdm[3224]: PAM adding faulty module: pam_kwallet.so
> Feb 02 10:50:05 myhost lightdm[3224]: PAM unable to dlopen(pam_kwallet5.so): /lib/security/pam_kwallet5.so: cannot open shared object file: No such file or directory
> Feb 02 10:50:05 myhost lightdm[3224]: PAM adding faulty module: pam_kwallet5.so

which I guess it's caused by this:

> # grep kwallet /etc/pam.d/lightd*
> /etc/pam.d/lightdm:auth optional pam_kwallet.so
> /etc/pam.d/lightdm:auth optional pam_kwallet5.so
> /etc/pam.d/lightdm:session optional pam_kwallet.so auto_start
> /etc/pam.d/lightdm:session optional pam_kwallet5.so auto_start
> /etc/pam.d/lightdm-greeter:auth optional pam_kwallet.so
> /etc/pam.d/lightdm-greeter:auth optional pam_kwallet5.so
> /etc/pam.d/lightdm-greeter:session optional pam_kwallet.so auto_start
> /etc/pam.d/lightdm-greeter:session optional pam_kwallet5.so auto_start

kwallet is a KDE program, which is not installed on MATE (and I think it shouldn't be), so I guess that such modules should not be [attempted to be] loaded.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: lightdm 1.26.0-0ubuntu1
ProcVersionSignature: Ubuntu 5.3.0-28.30~18.04.1-generic 5.3.13
Uname: Linux 5.3.0-28-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.9-0ubuntu7.9
Architecture: amd64
Date: Sun Feb 2 11:03:53 2020
InstallationDate: Installed on 2020-01-20 (12 days ago)
InstallationMedia: Ubuntu-MATE 18.04.3 LTS "Bionic Beaver" - Release amd64 (20190805)
SourcePackage: lightdm
UpgradeStatus: No upgrade log present (probably fresh install)

[Mélodie (meets)]

The following other bugs reports say the same thing: #1768488 and #1830079

I also find the same bug in Xubuntu 20.04 and in my own custom 20.04 Ubuntu.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.