Bug 1226218

Since upgrade from Leap 15.5 to 15.6 I'm no longer able to login with GDM when my Yubikey is inserted.
The system is configured to log in using pam_u2f.so requiring me to touch the Yubikey device to log in.

However since newest version, I get a username-field and a non functional 'back' button. Whenever I enter a username, it just refreshes and requests the username again. No password is asked, neither is asked to touch the Yubikey.

In the logging I find: 
---
gdm-smartcard][2964]: PAM unable to dlopen(/lib64/security/pam_pkcs11.so): /lib64/security/pam_pkcs11.so: kan gedeeld objectbestand niet openen: Bestand of map bestaat niet
gdm-smartcard][2964]: PAM adding faulty module: /lib64/security/pam_pkcs11.so
---

So I installed pam_pkcs11
Now when I enter the username in GDM it tells me to start smartcard authentication, and the light on the Yubikey lights up. When I touch it, it flickers once and then stays on again. Never proceeding login.
In the logging I now find:
---
gdm-smartcard][31888]: argument card_only is not supported by this module
gdm-smartcard][31888]: Failed to initialize crypto
gdm-smartcard][31888]: pam_pkcs11(gdm-smartcard:auth): Failed to initialize crypto
---

I also found this upstream bug: https://gitlab.gnome.org/GNOME/gdm/-/issues/877

It seems the yubikey is now detected as a smartcard despite it not been configured as a smartcard.
I also don't find understandable documentation describing how to configure Pam / GDM to accept the certificate on the Yubikey for a specific user.
Currently I can no longer log in using my Yubikey