Provided by: libpam-systemd_239-7ubuntu10_amd64 bug

NAME

       pam_systemd - Register user sessions in the systemd login manager

SYNOPSIS

       pam_systemd.so

DESCRIPTION

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

       On login, this module — in conjunction with systemd-logind.service — ensures the
       following:

        1. If it does not exist yet, the user runtime directory /run/user/$UID is either created
           or mounted as new "tmpfs" file system with quota applied, 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 was 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 systemd scope unit is created for the session. If this is the first concurrent
           session of the user, an implicit per-user slice unit below user.slice is automatically
           created and the scope placed into it. An instance of the system service user@.service,
           which runs the systemd user manager instance, is started.

       On logout, this module ensures the following:

        1. If enabled in logind.conf(5) (KillUserProcesses=), all processes of the session are
           terminated. If the last concurrent session of a user ends, the user's systemd instance
           will be terminated too, and so will the user's slice unit.

        2. If the last concurrent session of a user ends, the user runtime directory
           /run/user/$UID 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:

       class=
           Takes a string argument which sets the session class. The XDG_SESSION_CLASS
           environmental variable takes precedence. One of "user", "greeter", "lock-screen" or
           "background". See sd_session_get_class(3) for details about the session class.

       type=
           Takes a string argument which sets the session type. The XDG_SESSION_TYPE
           environmental variable takes precedence. One of "unspecified", "tty", "x11", "wayland"
           or "mir". See sd_session_get_type(3) for details about the session type.

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

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 filenames. 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
           the user's 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. For further details, see the XDG Base
           Directory Specification[1].  $XDG_RUNTIME_DIR is not set if the current user is not
           the original user of the session.

       The following environment variables are read by the module and may be used by the PAM
       service to pass metadata to the module:

       $XDG_SESSION_TYPE
           The session type. This may be used instead of session= on the module parameter line,
           and is usually preferred.

       $XDG_SESSION_CLASS
           The session class. This may be used instead of class= on the module parameter line,
           and is usually preferred.

       $XDG_SESSION_DESKTOP
           A single, short identifier string for the desktop environment. This may be used to
           indicate the session desktop used, where this applies and if this information is
           available. For example: "GNOME", or "KDE". It is recommended to use the same
           identifiers and capitalization as for $XDG_CURRENT_DESKTOP, as defined by the Desktop
           Entry Specification[2]. (However, note that $XDG_SESSION_DESKTOP only takes a single
           item, and not a colon-separated list like $XDG_CURRENT_DESKTOP.) See
           sd_session_get_desktop(3) for more details.

       $XDG_SEAT
           The seat name the session shall be registered for, if any.

       $XDG_VTNR
           The VT number the session shall be registered for, if any. (Only applies to seats with
           a VT available, such as "seat0")

       If not set, pam_systemd will determine the values for $XDG_SEAT and $XDG_VTNR based on the
       $DISPLAY variable.

SESSION LIMITS

       PAM modules earlier in the stack, that is those that come before pam_systemd.so, can set
       session scope limits using the PAM context objects. The data for these objects is provided
       as NUL-terminated C strings and maps directly to the respective unit resource control
       directives. Note that these limits apply to individual sessions of the user, they do not
       apply to all user processes as a combined whole. In particular, the per-user user@.service
       unit instance, which runs the systemd --user manager process and its children, and is
       tracked outside of any session, being shared by all the user's sessions, is not covered by
       these limits.

       See systemd.resource-control(5) for more information about the resources. Also, see
       pam_set_data(3) for additional information about how to set the context objects.

       systemd.memory_max
           Sets unit MemoryMax=.

       systemd.tasks_max
           Sets unit TasksMax=.

       systemd.cpu_weight
           Sets unit CPUWeight=.

       systemd.io_weight
           Sets unit IOWeight=.

       Example data as can be provided from an another PAM module:

           pam_set_data(handle, "systemd.memory_max", (void *)"200M", cleanup);
           pam_set_data(handle, "systemd.tasks_max",  (void *)"50",   cleanup);
           pam_set_data(handle, "systemd.cpu_weight", (void *)"100",  cleanup);
           pam_set_data(handle, "systemd.io_weight",  (void *)"340",  cleanup);

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

SEE ALSO

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

NOTES

        1. XDG Base Directory Specification
           http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html

        2. Desktop Entry Specification
           http://standards.freedesktop.org/desktop-entry-spec/latest/