Ubuntu Manpage: pam_systemd - Register user sessions in the systemd login manager

name
synopsis
description
options
module types provided
environment
example
see also

Provided by: libpam-systemd_204-5ubuntu20.31_amd64

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 the 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 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.

class=
Takes a string argument which sets the session class. The XDG_SESSION_CLASS environmental variable
takes precedence.

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 behavior 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