Dear Maintainer,

On a fresh Debian 13 (Trixie) installation with KDE Plasma 6 (x11),
the screen locker (kscreenlocker_greet) periodically fails to unlock
when the pam_sss.so module is missing.

Each time the session locks, the journal shows:

    PAM unable to dlopen(pam_sss.so): /usr/lib/security/pam_sss.so: cannot open shared object file: No such file or directory
    PAM adding faulty module: pam_sss.so

Sometimes the lock screen remains frozen or completely unresponsive
to password input.

Installing `libpam-sss` (not preinstalled by default) seems to fixe the issue.
--- Steps to Reproduce ---
1. Install Debian 13 (Trixie) with KDE Plasma (no libpam-sss installed)
2. Boot normally and log into a Plasma session (x11)
3. Lock the screen
4. Attempt to unlock — the greeter accepts input but does not respond or remains frozen.

--- Expected Behavior ---
The lock screen should always unlock normally with password entry

--- Actual Behavior ---
The greeter sometimes becomes unresponsive and fails to unlock.

--- Workaround ---
Installing `libpam-sss` resolves the problem:

    sudo apt install libpam-sss

--- System Information ---
- Plasma: 6.x (from Debian Trixie)
- Session: X11
- GPU: NVIDIA proprietary driver
- Kernel: 6.12.48+deb13-amd64

Dear Maintainer,

Operating System: Debian GNU/Linux 13
KDE Plasma Version: 6.3.6
KDE Frameworks Version: 6.13.0
Qt Version: 6.8.2
Kernel Version: 6.12.107+deb13-amd64 (64-bit)
Graphics Platform: Wayland
Processors: 12 × AMD Ryzen 5 1600 Six-Core Processor
Memory: 16 GiB of RAM (15.6 GiB usable)
Graphics Processor: NVIDIA GeForce RTX 3060/PCIe/SSE2
Manufacturer: MSI
Product Name: MS-7A37
System Version: 1.0
Nvidia driver:
NVIDIA-SMI 610.57.04
KMD Version: 610.57.04
CUDA UMD Version: 13.3

Output from journalctl:
Sep 05 17:24:33 charmander kscreenlocker_greet[30848]: PAM unable to
dlopen(pam_sss.so): /usr/lib/security/pam_sss.so: cannot open shared object
file: No such file or directory
Sep 05 17:24:33 charmander kscreenlocker_greet[30848]: PAM adding faulty
module: pam_sss.so

I had a failed sleep/wakeup around the time of the systemd error. Possibly
related?

Thanks!

Hey,

I cannot reproduce this issue. I don't have libpam-sss installed and I also
see the messages, but do not have the problem that the screen lock fails to
unlock. So the sss messages may be unrelated. I mark this to be fixed in KDE
Plasma 6.7, it would be great if you are able to test Debian testing or
unstable if this bug is gone for you too.

Regards,

hefee

journal messages:

PAM unable to dlopen(pam_sss.so): /usr/lib/security/pam_sss.so: cannot open
shared object file: No such file or directory
PAM adding faulty module: pam_sss.so
PAM unable to dlopen(pam_fprintd.so): /usr/lib/security/pam_fprintd.so: cannot
open shared object file: No such file or directory
PAM adding faulty module: pam_fprintd.so
pam_kwallet5(kde-smartcard:auth): pam_kwallet5: pam_sm_authenticate
pam_kwallet5(kde-smartcard:auth): pam_kwallet5: we were already executed
pam_kwallet5(kde-fingerprint:auth): pam_kwallet5: pam_sm_authenticate
pam_kwallet5(kde-fingerprint:auth): pam_kwallet5: we were already executed