Bug#1031389: gdm3: installing fprintd, but not libpam-fprintd makes login via gdm impossible

[Ansgar]

Package: gdm3
Version: 43.0-3
Severity: important
Tags: upstream

I wanted to try out the fingerprint reader in my laptop and installed
fprintd (but not libpam-fprintd yet). I also did not yet configure any
fingerprints.

However after a reboot I could no longer login (I could still unlock
the screen before the reboot). The system journal says:

+---
| Feb 16 09:35:34 gdm-fingerprint][1708]: PAM unable to dlopen(pam_fprintd.so): /lib/security/pam_fprintd.so: cannot open shared object file: No such file or directory
| Feb 16 09:35:34 gdm-fingerprint][1708]: PAM adding faulty module: pam_fprintd.so
| Feb 16 09:35:34 gdm-fingerprint][1708]: gkr-pam: no password is available for user
| Feb 16 09:35:34 gdm-fingerprint][1716]: PAM unable to dlopen(pam_fprintd.so): /lib/security/pam_fprintd.so: cannot open shared object file: No such file or directory
| Feb 16 09:35:34 gdm-fingerprint][1716]: PAM adding faulty module: pam_fprintd.so
| Feb 16 09:35:34 gdm-fingerprint][1716]: gkr-pam: no password is available for user
+---

There was no prompt for the password at all: I chose my user and was
returned back to the user selection.

I logged in via getty and installed libpam-fprintd and could login again.

GDM should not make login impossible when fprintd is installed and
libpam-fprintd is not. Login via password should still be possible in
this case.

I also noticed that for some reason there is a "]" after
"gdm-fingerprint" and before the PID in the log. That might also be a
minor bug.

Ansgar

-- System Information:
Debian Release: bookworm/sid
  APT prefers testing
  APT policy: (500, 'testing'), (300, 'buildd-unstable'), (300, 'unstable'), (1, 'buildd-experimental'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 6.1.0-4-amd64 (SMP w/16 CPU threads; PREEMPT)
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)
LSM: AppArmor: enabled

Versions of packages gdm3 depends on:
ii  accountsservice                       22.08.8-5
ii  adduser                               3.131
ii  dbus [default-dbus-system-bus]        1.14.6-1
ii  dbus-bin                              1.14.6-1
ii  dbus-daemon                           1.14.6-1
ii  dconf-cli                             0.40.0-4
ii  dconf-gsettings-backend               0.40.0-4
ii  debconf [debconf-2.0]                 1.5.82
ii  gir1.2-gdm-1.0                        43.0-3
ii  gnome-session [x-session-manager]     43.0-1
ii  gnome-session-bin                     43.0-1
ii  gnome-session-common                  43.0-1
ii  gnome-settings-daemon                 43.0-4
ii  gnome-shell                           43.2-2
ii  gnome-terminal [x-terminal-emulator]  3.46.7-1
ii  gsettings-desktop-schemas             43.0-1
ii  libaccountsservice0                   22.08.8-5
ii  libaudit1                             1:3.0.7-1.1+b3
ii  libc6                                 2.36-8
ii  libcanberra-gtk3-0                    0.30-10
ii  libcanberra0                          0.30-10
ii  libgdk-pixbuf-2.0-0                   2.42.10+dfsg-1+b1
ii  libgdm1                               43.0-3
ii  libglib2.0-0                          2.74.5-1
ii  libglib2.0-bin                        2.74.5-1
ii  libgtk-3-0                            3.24.36-3
ii  libgudev-1.0-0                        237-2
ii  libkeyutils1                          1.6.3-2
ii  libpam-modules                        1.5.2-6
ii  libpam-runtime                        1.5.2-6
ii  libpam-systemd [logind]               252.5-2
ii  libpam0g                              1.5.2-6
ii  librsvg2-common                       2.54.5+dfsg-1
ii  libselinux1                           3.4-1+b5
ii  libsystemd0                           252.5-2
ii  libx11-6                              2:1.8.3-3
ii  libxau6                               1:1.0.9-1
ii  libxcb1                               1.15-1
ii  libxdmcp6                             1:1.1.2-3
ii  polkitd                               122-3
ii  procps                                2:4.0.2-3
ii  systemd-sysv                          252.5-2
ii  ucf                                   3.0043+nmu1
ii  x11-common                            1:7.7+23
ii  x11-xserver-utils                     7.7+9+b1

Versions of packages gdm3 recommends:
ii  at-spi2-core                       2.46.0-5
ii  desktop-base                       12.0.2
ii  gnome-session [x-session-manager]  43.0-1
ii  x11-xkb-utils                      7.7+7
pn  xserver-xephyr                     <none>
pn  xserver-xorg                       <none>
ii  zenity                             3.44.0-1

Versions of packages gdm3 suggests:
ii  libpam-fprintd        1.94.2-2
ii  libpam-gnome-keyring  42.1-1+b1
pn  libpam-pkcs11         <none>
pn  libpam-sss            <none>
ii  orca                  43.1-1

-- Configuration Files:
/etc/pam.d/gdm-password changed [not included]

-- debconf information excluded