man/pam_systemd.xml

   1 <?xml version='1.0'?> <!--*-nxml-*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3         "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   This file is part of systemd.
   7
   8   Copyright 2010 Lennart Poettering
   9
  10   systemd is free software; you can redistribute it and/or modify it
  11   under the terms of the GNU Lesser General Public License as published by
  12   the Free Software Foundation; either version 2.1 of the License, or
  13   (at your option) any later version.
  14
  15   systemd is distributed in the hope that it will be useful, but
  16   WITHOUT ANY WARRANTY; without even the implied warranty of
  17   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18   Lesser General Public License for more details.
  19
  20   You should have received a copy of the GNU Lesser General Public License
  21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  22 -->
  23
  24 <refentry id="pam_systemd" conditional='HAVE_PAM'>
  25
  26         <refentryinfo>
  27                 <title>pam_systemd</title>
  28                 <productname>systemd</productname>
  29
  30                 <authorgroup>
  31                         <author>
  32                                 <contrib>Developer</contrib>
  33                                 <firstname>Lennart</firstname>
  34                                 <surname>Poettering</surname>
  35                                 <email>lennart@poettering.net</email>
  36                         </author>
  37                 </authorgroup>
  38         </refentryinfo>
  39
  40         <refmeta>
  41                 <refentrytitle>pam_systemd</refentrytitle>
  42                 <manvolnum>8</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>pam_systemd</refname>
  47                 <refpurpose>Register user sessions in the systemd login manager</refpurpose>
  48         </refnamediv>
  49
  50         <refsynopsisdiv>
  51                 <para><filename>pam_systemd.so</filename></para>
  52         </refsynopsisdiv>
  53
  54         <refsect1>
  55                 <title>Description</title>
  56
  57                 <para><command>pam_systemd</command> registers user
  58                 sessions with the systemd login manager
  59                 <citerefentry><refentrytitle>systemd-logind.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
  60                 and hence the systemd control group hierarchy.</para>
  61
  62                 <para>On login, this module ensures the following:</para>
  63
  64                 <orderedlist>
  65                         <listitem><para>If it does not exist yet, the
  66                         user runtime directory
  67                         <filename>/run/user/$USER</filename> is
  68                         created and its ownership changed to the user
  69                         that is logging in.</para></listitem>
  70
  71                         <listitem><para>The
  72                         <varname>$XDG_SESSION_ID</varname> environment
  73                         variable is initialized. If auditing is
  74                         available and
  75                         <command>pam_loginuid.so</command> run before
  76                         this module (which is highly recommended), the
  77                         variable is initialized from the auditing
  78                         session id
  79                         (<filename>/proc/self/sessionid</filename>). Otherwise
  80                         an independent session counter is
  81                         used.</para></listitem>
  82
  83                         <listitem><para>A new systemd scope unit is
  84                         created for the session. If this is the first
  85                         concurrent session of the user, an implicit
  86                         slice below <filename>user.slice</filename> is
  87                         automatically created and the scope placed in
  88                         it. In instance of the system service
  89                         <filename>user@.service</filename> which runs
  90                         the systemd user manager
  91                         instance.</para></listitem>
  92                 </orderedlist>
  93
  94                 <para>On logout, this module ensures the following:</para>
  95
  96                 <orderedlist>
  97                         <listitem><para>If this is enabled, all
  98                         processes of the session are terminated. If
  99                         the last concurrent session of a user ends, his
 100                         user systemd instance will be terminated too,
 101                         and so will the user's slice
 102                         unit.</para></listitem>
 103
 104                         <listitem><para>If the last concurrent session
 105                         of a user ends, the
 106                         <varname>$XDG_RUNTIME_DIR</varname> directory
 107                         and all its contents are removed,
 108                         too.</para></listitem>
 109                 </orderedlist>
 110
 111                 <para>If the system was not booted up with systemd as
 112                 init system, this module does nothing and immediately
 113                 returns PAM_SUCCESS.</para>
 114
 115         </refsect1>
 116
 117         <refsect1>
 118                 <title>Options</title>
 119
 120                 <para>The following options are understood:</para>
 121
 122                 <variablelist class='pam-directives'>
 123
 124                         <varlistentry>
 125                                 <term><option>class=</option></term>
 126
 127                                 <listitem><para>Takes a string
 128                                 argument which sets the session class.
 129                                 The XDG_SESSION_CLASS environmental variable
 130                                 takes precedence.</para></listitem>
 131                         </varlistentry>
 132
 133                         <varlistentry>
 134                                 <term><option>debug<optional>=</optional></option></term>
 135
 136                                 <listitem><para>Takes an optional
 137                                 boolean argument. If yes or without
 138                                 the argument, the module will log
 139                                 debugging information as it
 140                                 operates.</para></listitem>
 141                         </varlistentry>
 142                 </variablelist>
 143         </refsect1>
 144
 145         <refsect1>
 146                 <title>Module Types Provided</title>
 147
 148                 <para>Only <option>session</option> is provided.</para>
 149         </refsect1>
 150
 151         <refsect1>
 152                 <title>Environment</title>
 153
 154                 <para>The following environment variables are set for the processes of the user's session:</para>
 155
 156                 <variablelist class='environment-variables'>
 157                         <varlistentry>
 158                                 <term><varname>$XDG_SESSION_ID</varname></term>
 159
 160                                 <listitem><para>A session identifier,
 161                                 suitable to be used in filenames. The
 162                                 string itself should be considered
 163                                 opaque, although often it is just the
 164                                 audit session ID as reported by
 165                                 <filename>/proc/self/sessionid</filename>. Each
 166                                 ID will be assigned only once during
 167                                 machine uptime. It may hence be used
 168                                 to uniquely label files or other
 169                                 resources of this
 170                                 session.</para></listitem>
 171                         </varlistentry>
 172
 173                         <varlistentry>
 174                                 <term><varname>$XDG_RUNTIME_DIR</varname></term>
 175
 176                                 <listitem><para>Path to a user-private
 177                                 user-writable directory that is bound
 178                                 to the user login time on the
 179                                 machine. It is automatically created
 180                                 the first time a user logs in and
 181                                 removed on his final logout. If a user
 182                                 logs in twice at the same time, both
 183                                 sessions will see the same
 184                                 <varname>$XDG_RUNTIME_DIR</varname>
 185                                 and the same contents. If a user logs
 186                                 in once, then logs out again, and logs
 187                                 in again, the directory contents will
 188                                 have been lost in between, but
 189                                 applications should not rely on this
 190                                 behavior and must be able to deal with
 191                                 stale files. To store session-private
 192                                 data in this directory, the user should
 193                                 include the value of <varname>$XDG_SESSION_ID</varname>
 194                                 in the filename. This directory shall
 195                                 be used for runtime file system
 196                                 objects such as <constant>AF_UNIX</constant> sockets,
 197                                 FIFOs, PID files and similar. It is
 198                                 guaranteed that this directory is
 199                                 local and offers the greatest possible
 200                                 file system feature set the
 201                                 operating system
 202                                 provides.</para></listitem>
 203                         </varlistentry>
 204                 </variablelist>
 205         </refsect1>
 206
 207         <refsect1>
 208                 <title>Example</title>
 209
 210                 <programlisting>#%PAM-1.0
 211 auth       required     pam_unix.so
 212 auth       required     pam_nologin.so
 213 account    required     pam_unix.so
 214 password   required     pam_unix.so
 215 session    required     pam_unix.so
 216 session    required     pam_loginuid.so
 217 session    required     pam_systemd.so</programlisting>
 218         </refsect1>
 219
 220         <refsect1>
 221                 <title>See Also</title>
 222                 <para>
 223                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 224                         <citerefentry><refentrytitle>systemd-logind.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 225                         <citerefentry><refentrytitle>logind.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 226                         <citerefentry><refentrytitle>loginctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 227                         <citerefentry><refentrytitle>pam.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 228                         <citerefentry><refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 229                         <citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 230                         <citerefentry><refentrytitle>pam_loginuid</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 231                         <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 232                         <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 233                         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 234                 </para>
 235         </refsect1>
 236
 237 </refentry>