pam_systemd_home(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | HOME AREA SUPPORT | MODULE TYPES PROVIDED | ENVIRONMENT | EXAMPLE | SEE ALSO | NOTES | COLOPHON

PAM_SYSTEMD_HOME(8)          pam_systemd_home         PAM_SYSTEMD_HOME(8)

NAME         top

       pam_systemd_home - Authenticate users and mount home directories
       via systemd-homed.service

SYNOPSIS         top

       pam_systemd_home.so

DESCRIPTION         top

       pam_systemd_home ensures that home directories managed by
       systemd-homed.service(8) are automatically activated (mounted) on
       user login, and are deactivated (unmounted) when the last session
       of the user ends. For such users, it also provides authentication
       (when per-user disk encryption is used, the disk encryption key is
       derived from the authentication credential supplied at login
       time), account management (the JSON user record[1] embedded in the
       home store contains account details), and implements the updating
       of the encryption password (which is also used for user
       authentication).

OPTIONS         top

       The following options are understood:

       suspend=
           Takes a boolean argument. If true, the home directory of the
           user will be suspended automatically during system suspend; if
           false it will remain active. Automatic suspending of the home
           directory improves security substantially as secret key
           material is automatically removed from memory before the
           system is put to sleep and must be re-acquired (through user
           re-authentication) when coming back from suspend. It is
           recommended to set this parameter for all PAM applications
           that have support for automatically re-authenticating via PAM
           on system resume. If multiple sessions of the same user are
           open in parallel the user's home directory will be left
           unsuspended on system suspend as long as at least one of the
           sessions does not set this parameter to on. Defaults to off.

           Note that TTY logins generally do not support
           re-authentication on system resume. Re-authentication on
           system resume is primarily a concept implementable in
           graphical environments, in the form of lock screens brought up
           automatically when the system goes to sleep. This means that
           if a user concurrently uses graphical login sessions that
           implement the required re-authentication mechanism and console
           logins that do not, the home directory is not locked during
           suspend, due to the logic explained above. That said, it is
           possible to set this field for TTY logins too, ignoring the
           fact that TTY logins actually do not support the
           re-authentication mechanism. In that case the TTY sessions
           will appear hung until the user logs in on another virtual
           terminal (regardless of whether via another TTY session or
           graphically) which will resume the home directory and unblock
           the original TTY session. (Do note that lack of screen locking
           on TTY sessions means even though the TTY session appears
           hung, keypresses can still be queued into it, and the existing
           screen contents be read without re-authentication; this
           limitation is unrelated to the home directory management
           pam_systemd_home and systemd-homed.service implement.)

           Turning this option on by default is highly recommended for
           all sessions, but only if the service managing these sessions
           correctly implements the aforementioned re-authentication.
           Note that the re-authentication must take place from a
           component running outside of the user's context, so that it
           does not require access to the user's home directory for
           operation. Traditionally, most desktop environments do not
           implement screen locking this way, and need to be updated
           accordingly.

           This setting may also be controlled via the
           $SYSTEMD_HOME_SUSPEND environment variable (see below), which
           pam_systemd_home reads during initialization and sets for
           sessions. If both the environment variable is set and the
           module parameter specified the latter takes precedence.

           Added in version 245.

       debug[=]
           Takes an optional boolean argument. If yes or without the
           argument, the module will log debugging information as it
           operates.

           Added in version 245.

HOME AREA SUPPORT         top

       Home directories managed by systemd-homed.service(8) support
       multiple home "areas", which are additional secondary home
       directories of the user within the primary home directory. An
       example: at login time if a user "lennart" with a home directory
       of /home/lennart specifies "lennart%versuch1" as account name
       during login, then pam_systemd_home will execute a login into
       "lennart" but ensure that the $HOME variable is set to
       /home/lennart/Areas/versuch1 instead of the usual /home/lennart.

       This is particularly useful when sharing the same home directory
       between multiple systems (for example between a host and a VM),
       with the desire to share the home directory to a large degree, but
       still have separate session configuration in place.

       Note that the default area to log into can also be encoded in the
       user record, and it can be specified among pam_systemd(8)
       configuration parameters. However, an explicit area specified at
       login time (via the "%" described above) overrides any such
       default. Also note that simply suffixing an account with "%" at
       login time (i.e. specifying an empty area name) has the effect of
       ensuring a login into the primary home directory, overriding any
       default area configuration via the user record or PAM.

       Note that not all login mechanisms are compatible with the "%"
       syntax at login time. Most notably ssh(8) is not.

       Note that the area directory to log into must exist for the area
       specification to be respected. If an area is specified during
       login via the "%" logic (or the other mentioned mechanisms) and it
       does not actually exist the request will be ignored, and the user
       will log into the primary home directory instead.

       Typically, in order to make use of the mechanism set up an area
       first, like this:

           lennart@zeta$ mkdir -p ~/Areas
           lennart@zeta$ cp -av /etc/skel ~/Areas/versuch1

       This should be enough to log into the newly created area, either
       via a regular terminal (using "lennart%versuch1" when prompted for
       a user name), or via run0(1):

           lennart@zeta$ run0 --area=versuch1

MODULE TYPES PROVIDED         top

       The module implements all four PAM operations: auth (to allow
       authentication using the encrypted data), account (because users
       with systemd-homed.service user accounts are described in a JSON
       user record[1] and may be configured in more detail than in the
       traditional Linux user database), session (because user sessions
       must be tracked in order to implement automatic release when the
       last session of the user is gone), password (to change the
       encryption password — also used for user authentication — through
       PAM).

ENVIRONMENT         top

       The following environment variables are initialized by the module
       and available to the processes of the user's session:

       $SYSTEMD_HOME=1
           Indicates that the user's home directory is managed by
           systemd-homed.service.

           Added in version 245.

       $SYSTEMD_HOME_SUSPEND=
           Indicates whether the session has been registered with the
           suspend mechanism enabled or disabled (see above). The
           variable's value is either "0" or "1". Note that the module
           both reads the variable when initializing, and sets it for
           sessions.

           Added in version 246.

EXAMPLE         top

       Here's an example PAM configuration fragment that permits users
       managed by systemd-homed.service to log in:

           #%PAM-1.0
               -auth     [success=done authtok_err=bad perm_denied=bad maxtries=bad default=ignore] pam_systemd_home.so
           auth      sufficient pam_unix.so
           auth      required   pam_deny.so

           account   required   pam_nologin.so
           -account  [success=done authtok_expired=bad new_authtok_reqd=bad maxtries=bad acct_expired=bad default=ignore] pam_systemd_home.so
           account   required   pam_unix.so

           -password sufficient pam_systemd_home.so
           password  sufficient pam_unix.so sha512 shadow try_first_pass
           password  required   pam_deny.so

           -session  optional   pam_keyinit.so revoke
           -session  optional   pam_loginuid.so
           -session  optional   pam_systemd_home.so
           -session  optional   pam_systemd.so
           session   required   pam_unix.so

SEE ALSO         top

       systemd(1), systemd-homed.service(8), homed.conf(5), homectl(1),
       pam_systemd(8), pam.conf(5), pam.d(5), pam(8)

NOTES         top

        1. JSON user record
           https://systemd.io/USER_RECORD/

COLOPHON         top

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have a
       bug report for this manual page, see
       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
       This page was obtained from the project's upstream Git repository
       ⟨https://github.com/systemd/systemd.git⟩ on 2025-08-11.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2025-08-11.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there is
       a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

systemd 258~rc2                                       PAM_SYSTEMD_HOME(8)

Pages that refer to this page: homectl(1)run0(1)systemd.directives(7)systemd.index(7)pam_systemd(8)systemd-homed.service(8)