PAM_SYSTEMD(8)

NAME
pam_systemd - Register user sessions in the systemd login manager

SYNOPSIS

pam_systemd.so

DESCRIPTION

pam_systemd registers user sessions in the systemd login manager systemd-logind.service(8), and hence the systemd control group hierarchy.

On login, this module ensures the following:

    1. If it does not exist yet, the user runtime directory /run/user/$USER is created and its ownership changed to the user that is logging in.

    2. The $XDG_SESSION_ID environment variable is initialized. If auditing is available and pam_loginuid.so run before this module (which is highly recommended), the variable is initialized from the auditing session id (/proc/self/sessionid). Otherwise an independent session counter is used.

    3. A new control group /user/$USER/$XDG_SESSION_ID is created and the login process moved into it.

On logout, this module ensures the following:

    1. If $XDG_SESSION_ID is set and kill-session-processes=1 specified, all remaining processes in the /user/$USER/$XDG_SESSION_ID control group are killed and the control group is removed.

    2. If last subgroup of the /user/$USER control group was removed the $XDG_RUNTIME_DIR directory and all its contents are removed, too.

If the system was not booted up with systemd as init system, this module does nothing and immediately returns PAM_SUCCESS.

OPTIONS

The following options are understood:

kill-session-processes=
    Takes a boolean argument. If true, all processes created by the user during his session and from his session will be terminated when he logs out from his session.

kill-only-users=
    Takes a comma separated list of user names or numeric user ids as argument. If this option is used the effect of the kill-session-processes= options will apply only to the listed users. If this option is not used the option applies to all local users. Note that kill-exclude-users= takes precedence over this list and is hence subtracted from the list specified here.

kill-exclude-users=
    Takes a comma separated list of user names or numeric user ids as argument. Users listed in this argument will not be subject to the effect of kill-session-processes=. Note that that this option takes precedence over kill-only-users=, and hence whatever is listed for kill-exclude-users= is guaranteed to never be killed by this PAM module, independent of any other configuration setting.

controllers=
    Takes a comma separated list of control group controllers in which hierarchies a user/session control group will be created by default for each user logging in, in addition to the control group in the named 'name=systemd' hierarchy. If omitted, defaults to an empty list.

reset-controllers=
    Takes a comma separated list of control group controllers in which hierarchies the logged in processes will be reset to the root control group.

debug=
    Takes a boolean argument. If yes, the module will log debugging information as it operates.

Note that setting kill-session-processes=1 will break tools like screen(1).

Note that kill-session-processes=1 is a stricter version of KillUserProcesses=1 which may be configured system-wide in logind.conf(5). The former kills processes of a session as soon as it ends, the latter kills processes as soon as the last session of the user ends.

If the options are omitted they default to kill-session-processes=0, kill-only-users=, kill-exclude-users=, controllers=, reset-controllers=, debug=no.

MODULE TYPES PROVIDED

Only session is provided.

ENVIRONMENT

The following environment variables are set for the processes of the user's session:

$XDG_SESSION_ID
    A session identifier, suitable to be used in file names. The string itself should be considered opaque, although often it is just the audit session ID as reported by /proc/self/sessionid. Each ID will be assigned only once during machine uptime. It may hence be used to uniquely label files or other resources of this session.

$XDG_RUNTIME_DIR
    Path to a user-private user-writable directory that is bound to the user login time on the machine. It is automatically created the first time a user logs in and removed on his final logout. If a user logs in twice at the same time, both sessions will see the same $XDG_RUNTIME_DIR and the same contents. If a user logs in once, then logs out again, and logs in again, the directory contents will have been lost in between, but applications should not rely on this behaviour and must be able to deal with stale files. To store session-private data in this directory the user should include the value of $XDG_SESSION_ID in the filename. This directory shall be used for runtime file system objects such as AF_UNIX sockets, FIFOs, PID files and similar. It is guaranteed that this directory is local and offers the greatest possible file system feature set the operating system provides.

EXAMPLE

    #%PAM-1.0
    auth       required     pam_unix.so
    auth       required     pam_nologin.so
    account    required     pam_unix.so
    password   required     pam_unix.so
    session    required     pam_unix.so
    session    required     pam_loginuid.so
    session    required     pam_systemd.so kill-session-processes=1

SEE ALSO

systemd(1), systemd-logind.service(8), logind.conf(5), loginctl(1), pam.conf(5), pam.d(5), pam(8), pam_loginuid(8)

AUTHOR

Lennart Poettering <lennart@poettering.net>
    Developer