man/pam_systemd.xml

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  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=</option></term>
 135
 136                                 <listitem><para>Takes a boolean
 137                                 argument. If yes, the module will log
 138                                 debugging information as it
 139                                 operates.</para></listitem>
 140                         </varlistentry>
 141                 </variablelist>
 142         </refsect1>
 143
 144         <refsect1>
 145                 <title>Module Types Provided</title>
 146
 147                 <para>Only <option>session</option> is provided.</para>
 148         </refsect1>
 149
 150         <refsect1>
 151                 <title>Environment</title>
 152
 153                 <para>The following environment variables are set for the processes of the user's session:</para>
 154
 155                 <variablelist class='environment-variables'>
 156                         <varlistentry>
 157                                 <term><varname>$XDG_SESSION_ID</varname></term>
 158
 159                                 <listitem><para>A session identifier,
 160                                 suitable to be used in filenames. The
 161                                 string itself should be considered
 162                                 opaque, although often it is just the
 163                                 audit session ID as reported by
 164                                 <filename>/proc/self/sessionid</filename>. Each
 165                                 ID will be assigned only once during
 166                                 machine uptime. It may hence be used
 167                                 to uniquely label files or other
 168                                 resources of this
 169                                 session.</para></listitem>
 170                         </varlistentry>
 171
 172                         <varlistentry>
 173                                 <term><varname>$XDG_RUNTIME_DIR</varname></term>
 174
 175                                 <listitem><para>Path to a user-private
 176                                 user-writable directory that is bound
 177                                 to the user login time on the
 178                                 machine. It is automatically created
 179                                 the first time a user logs in and
 180                                 removed on his final logout. If a user
 181                                 logs in twice at the same time, both
 182                                 sessions will see the same
 183                                 <varname>$XDG_RUNTIME_DIR</varname>
 184                                 and the same contents. If a user logs
 185                                 in once, then logs out again, and logs
 186                                 in again, the directory contents will
 187                                 have been lost in between, but
 188                                 applications should not rely on this
 189                                 behavior and must be able to deal with
 190                                 stale files. To store session-private
 191                                 data in this directory, the user should
 192                                 include the value of <varname>$XDG_SESSION_ID</varname>
 193                                 in the filename. This directory shall
 194                                 be used for runtime file system
 195                                 objects such as <constant>AF_UNIX</constant> sockets,
 196                                 FIFOs, PID files and similar. It is
 197                                 guaranteed that this directory is
 198                                 local and offers the greatest possible
 199                                 file system feature set the
 200                                 operating system
 201                                 provides.</para></listitem>
 202                         </varlistentry>
 203                 </variablelist>
 204         </refsect1>
 205
 206         <refsect1>
 207                 <title>Example</title>
 208
 209                 <programlisting>#%PAM-1.0
 210 auth       required     pam_unix.so
 211 auth       required     pam_nologin.so
 212 account    required     pam_unix.so
 213 password   required     pam_unix.so
 214 session    required     pam_unix.so
 215 session    required     pam_loginuid.so
 216 session    required     pam_systemd.so</programlisting>
 217         </refsect1>
 218
 219         <refsect1>
 220                 <title>See Also</title>
 221                 <para>
 222                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 223                         <citerefentry><refentrytitle>systemd-logind.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 224                         <citerefentry><refentrytitle>logind.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 225                         <citerefentry><refentrytitle>loginctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 226                         <citerefentry><refentrytitle>pam.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 227                         <citerefentry><refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 228                         <citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 229                         <citerefentry><refentrytitle>pam_loginuid</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 230                         <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 231                         <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 232                         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 233                 </para>
 234         </refsect1>
 235
 236 </refentry>