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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
        "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<!--
  This file is part of systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->

<refentry id="pam_systemd">

        <refentryinfo>
                <title>pam_systemd</title>
                <productname>systemd</productname>

                <authorgroup>
                        <author>
                                <contrib>Developer</contrib>
                                <firstname>Lennart</firstname>
                                <surname>Poettering</surname>
                                <email>lennart@poettering.net</email>
                        </author>
                </authorgroup>
        </refentryinfo>

        <refmeta>
                <refentrytitle>pam_systemd</refentrytitle>
                <manvolnum>8</manvolnum>
        </refmeta>

        <refnamediv>
                <refname>pam_systemd</refname>
                <refpurpose>Register user sessions in the systemd control group hierarchy</refpurpose>
        </refnamediv>

        <refsynopsisdiv>
                <cmdsynopsis>
                        <command>pam_systemd.so</command>
                </cmdsynopsis>
        </refsynopsisdiv>

        <refsect1>
                <title>Description</title>

                <para><command>pam_systemd</command> registers user
                sessions in the systemd control group
                hierarchy.</para>

                <para>On login, this module ensures the following:</para>

                <orderedlist>
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                        <listitem><para>If it does not exist yet, the
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                        user runtime directory
                        <filename>/var/run/user/$USER</filename> is
                        created and its ownership changed to the user
                        that is logging in.</para></listitem>

                        <listitem><para>If
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                        <option>create-session=1</option> is set, the
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                        <varname>$XDG_SESSION_ID</varname> environment
                        variable is initialized. If auditing is
                        available and
                        <command>pam_loginuid.so</command> run before
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                        this module (which is highly recommended), the
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                        variable is initialized from the auditing
                        session id
                        (<filename>/proc/self/sessionid</filename>). Otherwise
                        an independent session counter is
                        used.</para></listitem>

                        <listitem><para>If
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                        <option>create-session=1</option> is set, a new
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                        control group
                        <filename>/user/$USER/$XDG_SESSION_ID</filename>
                        is created and the login process moved into
                        it.</para></listitem>

                        <listitem><para>If
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                        <option>create-session=0</option> is set, a new
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                        control group
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                        <filename>/user/$USER/user</filename>
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                        is created and the login process moved into
                        it.</para></listitem>

                </orderedlist>

                <para>On logout, this module ensures the following:</para>

                <orderedlist>
                        <listitem><para>If
                        <varname>$XDG_SESSION_ID</varname> is set and
                        <option>kill-session=1</option> specified, all
                        remaining processes in the
                        <filename>/user/$USER/$XDG_SESSION_ID</filename>
                        control group are killed and the control group
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                        is removed.</para></listitem>
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                        <listitem><para>If
                        <varname>$XDG_SESSION_ID</varname> is set and
                        <option>kill-session=0</option> specified, all
                        remaining processes in the
                        <filename>/user/$USER/$XDG_SESSION_ID</filename>
                        control group are migrated to
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                        <filename>/user/$USER/user</filename> and
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                        the original control group is
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                        removed.</para></listitem>

                        <listitem><para>If
                        <option>kill-user=1</option> is specified, and
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                        no other user session control group remains,
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                        except
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                        <filename>/user/$USER/user</filename>,
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                        all remaining processes in the
                        <filename>/user/$USER</filename> hierarchy
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                        are killed and the control group is removed.</para></listitem>
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                        <listitem><para>If
                        <option>kill-user=0</option> is specified, and
                        no process remains in the
                        <filename>/user/$USER</filename> hierarchy the
                        control group is removed.</para></listitem>

                        <listitem><para>If the
                        <filename>/user/$USER</filename> control group
                        was removed the
                        <varname>$XDG_RUNTIME_DIR</varname> directory
                        and all its contents are
                        removed, too.</para></listitem>
                </orderedlist>

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

        </refsect1>

        <refsect1>
                <title>Options</title>

                <para>The following options are understood:</para>

                <variablelist>
                        <varlistentry>
                                <term><option>create-session=</option></term>

                                <listitem><para>Takes a boolean
                                argument. If true, a new session is
                                created: the
                                <varname>$XDG_SESSION_ID</varname>
                                environment variable is set and the
                                login process moved to the
                                <filename>/user/$USER/$XDG_SESSION_ID</filename>
                                control group. It is recommended that
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                                all services which are directly created
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                                on the user's behalf set this
                                option. Only for services that shall
                                automatically be terminated when the
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                                user logs out completely, otherwise
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                                <varname>create-session=0</varname>
                                should be set.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>kill-session=</option></term>

                                <listitem><para>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.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>kill-user=</option></term>

                                <listitem><para>Takes a boolean
                                argument. If true, all processes
                                created by the user during his session
                                and from his session will be
                                terminated after he logged out
                                completely. This is a weaker version
                                of <option>kill-session=1</option> and is
                                more friendly for users logged in more
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                                than once, as their processes are
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                                terminated only on their complete
                                logout.</para></listitem>
                        </varlistentry>
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                        <varlistentry>
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                                <term><option>kill-only-users=</option></term>
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                                <listitem><para>Takes a comma
                                separated list of user names or
                                numeric user ids as argument. If this
                                option is used the effect of the
                                <option>kill-session=</option> and
                                <option>kill-user=</option> options
                                will apply only to the listed
                                users. If this option is not used the
                                option applies to all local
                                users. Note that
                                <option>kill-exclude-users=</option>
                                takes precedence over this list and is
                                hence subtracted from the list
                                specified here.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>kill-exclude-users=</option></term>

                                <listitem><para>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
                                <option>kill-session=</option> or
                                <option>kill-user=</option>.  Note
                                that that this option takes precedence
                                over
                                <option>kill-only-users=</option>, and
                                hence whatever is listed for
                                <option>kill-exclude-users=</option>
                                is guaranteed to never be killed by
                                this PAM module, independent of any
                                other configuration
                                setting.</para></listitem>
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                        </varlistentry>

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                        <varlistentry>
                                <term><option>controllers=</option></term>

                                <listitem><para>Takes a comma
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                                separated list of cgroup controllers
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                                in which hierarchies a user/session
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                                cgroup will be created by default for
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                                each user logging in, in addition to
                                the cgroup in the named 'name=systemd'
                                hierarchy. If ommited, defaults to an
                                empty list. This may be used to move
                                user sessions into their own groups in
                                the 'cpu' hierarchy which ensures that
                                every logged in user gets an equal
                                amount of CPU time regardless how many
                                processes he has
                                started.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>reset-controllers=</option></term>

                                <listitem><para>Takes a comma
                                separated list of cgroup controllers
                                in which hierarchies the logged in
                                processes will be reset to the root
                                cgroup. If ommited, defaults to 'cpu',
                                meaning that a 'cpu' cgroup grouping
                                inherited from the login manager will
                                be reset for the processes of the
                                logged in user.</para></listitem>
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                        </varlistentry>
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                </variablelist>

                <para>Note that setting <varname>kill-user=1</varname>
                or even <varname>kill-session=1</varname> will break
                tools like
                <citerefentry><refentrytitle>screen</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>

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                <para>If the options are omitted they default to
                <option>create-session=1</option>,
                <option>kill-session=0</option>,
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                <option>kill-user=0</option>,
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                <option>reset-controllers=cpu</option>,
                <option>kill-only-users=</option>,
                <option>kill-exclude-users=root</option>.</para>
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        </refsect1>

        <refsect1>
                <title>Module Types Provided</title>

                <para>Only <option>session</option> is provided.</para>
        </refsect1>

        <refsect1>
                <title>Environment</title>

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                <para>The following environment variables are set for the processes of the user's session:</para>

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                <variablelist>
                        <varlistentry>
                                <term><varname>$XDG_SESSION_ID</varname></term>

                                <listitem><para>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
                                <filename>/proc/self/sessionid</filename>. 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.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>$XDG_RUNTIME_DIR</varname></term>

                                <listitem><para>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
                                <varname>$XDG_RUNTIME_DIR</varname>
                                and the same contents. If a user logs
                                in once, then logs out again, and logs
                                in again, the directory contents will
                                have been lost in between, but
                                applications should not rely on this
                                behaviour and must be able to deal with
                                stale files. To store session-private
                                data in this directory the user should
                                include the value of <varname>$XDG_SESSION_ID</varname>
                                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.</para></listitem>
                        </varlistentry>
                </variablelist>
        </refsect1>

        <refsect1>
                <title>Example</title>

                <programlisting>#%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
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session    required     pam_systemd.so kill-user=1</programlisting>
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        </refsect1>

        <refsect1>
                <title>See Also</title>
                <para>
                        <citerefentry><refentrytitle>pam.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>pam_loginuid</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
                </para>
        </refsect1>

</refentry>