NAME

       pam_systemd_loadkey - Read password from kernel keyring and set it as PAM authtok

SYNOPSIS

       pam_systemd_loadkey.so

DESCRIPTION

       pam_systemd_loadkey reads a NUL-separated password list from the kernel keyring, and sets
       the last password in the list as the PAM authtok.

       The password list is supposed to be stored in the "user" keyring of the root user, by an
       earlier call to systemd-ask-password(1) with --keyname=. You can pass the keyname to
       pam_systemd_loadkey via the keyname= option.

OPTIONS

       The following options are understood:

       keyname=
           Takes a string argument which sets the keyname to read. The default is "cryptsetup".
           During boot, systemd-cryptsetup@.service(8) stores a passphrase or PIN in the keyring.
           The LUKS2 volume key can also be used, via the link-volume-key option in crypttab(5).

           Table 1.  Possible values for keyname.
           ┌───────────┬────────────────────────────┐
           │Value      │ Description                │
           ├───────────┼────────────────────────────┤
           │cryptsetup │ Passphrase or recovery key │
           ├───────────┼────────────────────────────┤
           │fido2-pin  │ Security token PIN         │
           ├───────────┼────────────────────────────┤
           │luks2-pin  │ LUKS2 token PIN            │
           ├───────────┼────────────────────────────┤
           │tpm2-pin   │ TPM2 PIN                   │
           └───────────┴────────────────────────────┘
           Added in version 255.

       debug
           The module will log debugging information as it operates.

           Added in version 255.

EXAMPLE

       This module is intended to be used when you use LUKS with a passphrase, enable autologin
       in the display manager, and want to unlock Gnome Keyring / KDE KWallet automatically. So
       in total, you only enter one password during boot.

       You need to set the password of your Gnome Keyring/KWallet to the same as your LUKS
       passphrase. Then add the following lines to your display manager's PAM config under
       /etc/pam.d/ (e.g.  sddm-autologin):

           -auth       optional    pam_systemd_loadkey.so
           -auth       optional    pam_gnome_keyring.so
           -session    optional    pam_gnome_keyring.so auto_start
           -session    optional    pam_kwallet5.so auto_start

       And add the following lines to your display manager's systemd service file, so it can
       access root's keyring:

           [Service]
           KeyringMode=inherit

       In this setup, early during the boot process, systemd-cryptsetup@.service(8) will ask for
       the passphrase and store it in the kernel keyring with the keyname "cryptsetup". Then when
       the display manager does the autologin, pam_systemd_loadkey will read the passphrase from
       the kernel keyring, set it as the PAM authtok, and then pam_gnome_keyring and pam_kwallet5
       will unlock with the same passphrase.