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> was 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 into
  88                         it. An instance of the system service
  89                         <filename>user@.service</filename>, which runs
  90                         the systemd user manager instance, is started.
  91                         </para></listitem>
  92                 </orderedlist>
  93
  94                 <para>On logout, this module ensures the following:</para>
  95
  96                 <orderedlist>
  97                         <listitem><para>If enabled in
  98                         <citerefentry><refentrytitle>logind.conf</refentrytitle>
  99                         <manvolnum>5</manvolnum></citerefentry>, all
 100                         processes of the session are terminated. If
 101                         the last concurrent session of a user ends,
 102                         ther user's systemd instance will be
 103                         terminated too, and so will the user's slice
 104                         unit.</para></listitem>
 105
 106                         <listitem><para>If the last concurrent session
 107                         of a user ends, the
 108                         <varname>$XDG_RUNTIME_DIR</varname> directory
 109                         and all its contents are removed,
 110                         too.</para></listitem>
 111                 </orderedlist>
 112
 113                 <para>If the system was not booted up with systemd as
 114                 init system, this module does nothing and immediately
 115                 returns PAM_SUCCESS.</para>
 116
 117         </refsect1>
 118
 119         <refsect1>
 120                 <title>Options</title>
 121
 122                 <para>The following options are understood:</para>
 123
 124                 <variablelist class='pam-directives'>
 125
 126                         <varlistentry>
 127                                 <term><option>class=</option></term>
 128
 129                                 <listitem><para>Takes a string
 130                                 argument which sets the session class.
 131                                 The XDG_SESSION_CLASS environmental variable
 132                                 takes precedence. One of
 133                                 <literal>user</literal>,
 134                                 <literal>greeter</literal>,
 135                                 <literal>lock-screen</literal> or
 136                                 <literal>background</literal>. See
 137                                 <citerefentry><refentrytitle>sd_session_get_class</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 138                                 for details about the session class.</para></listitem>
 139                         </varlistentry>
 140
 141                         <varlistentry>
 142                                 <term><option>type=</option></term>
 143
 144                                 <listitem><para>Takes a string
 145                                 argument which sets the session type.
 146                                 The XDG_SESSION_TYPE environmental
 147                                 variable takes precedence. One of
 148                                 <literal>unspecified</literal>,
 149                                 <literal>tty</literal>,
 150                                 <literal>x11</literal>,
 151                                 <literal>wayland</literal> or
 152                                 <literal>mir</literal>. See
 153                                 <citerefentry><refentrytitle>sd_session_get_type</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 154                                 for details about the session type.</para></listitem>
 155                         </varlistentry>
 156
 157                         <varlistentry>
 158                                 <term><option>debug<optional>=</optional></option></term>
 159
 160                                 <listitem><para>Takes an optional
 161                                 boolean argument. If yes or without
 162                                 the argument, the module will log
 163                                 debugging information as it
 164                                 operates.</para></listitem>
 165                         </varlistentry>
 166                 </variablelist>
 167         </refsect1>
 168
 169         <refsect1>
 170                 <title>Module Types Provided</title>
 171
 172                 <para>Only <option>session</option> is provided.</para>
 173         </refsect1>
 174
 175         <refsect1>
 176                 <title>Environment</title>
 177
 178                 <para>The following environment variables are set for the processes of the user's session:</para>
 179
 180                 <variablelist class='environment-variables'>
 181                         <varlistentry>
 182                                 <term><varname>$XDG_SESSION_ID</varname></term>
 183
 184                                 <listitem><para>A session identifier,
 185                                 suitable to be used in filenames. The
 186                                 string itself should be considered
 187                                 opaque, although often it is just the
 188                                 audit session ID as reported by
 189                                 <filename>/proc/self/sessionid</filename>. Each
 190                                 ID will be assigned only once during
 191                                 machine uptime. It may hence be used
 192                                 to uniquely label files or other
 193                                 resources of this
 194                                 session.</para></listitem>
 195                         </varlistentry>
 196
 197                         <varlistentry>
 198                                 <term><varname>$XDG_RUNTIME_DIR</varname></term>
 199
 200                                 <listitem><para>Path to a user-private
 201                                 user-writable directory that is bound
 202                                 to the user login time on the
 203                                 machine. It is automatically created
 204                                 the first time a user logs in and
 205                                 removed on the user's final logout. If
 206                                 a user logs in twice at the same time,
 207                                 both sessions will see the same
 208                                 <varname>$XDG_RUNTIME_DIR</varname>
 209                                 and the same contents. If a user logs
 210                                 in once, then logs out again, and logs
 211                                 in again, the directory contents will
 212                                 have been lost in between, but
 213                                 applications should not rely on this
 214                                 behavior and must be able to deal with
 215                                 stale files. To store session-private
 216                                 data in this directory, the user should
 217                                 include the value of <varname>$XDG_SESSION_ID</varname>
 218                                 in the filename. This directory shall
 219                                 be used for runtime file system
 220                                 objects such as <constant>AF_UNIX</constant> sockets,
 221                                 FIFOs, PID files and similar. It is
 222                                 guaranteed that this directory is
 223                                 local and offers the greatest possible
 224                                 file system feature set the
 225                                 operating system
 226                                 provides.</para></listitem>
 227                         </varlistentry>
 228
 229                 </variablelist>
 230
 231                 <para>The following environment variables are read by
 232                 the module and may be used by the PAM service to pass
 233                 metadata to the module:</para>
 234
 235                 <variablelist class='environment-variables'>
 236                         <varlistentry>
 237                                 <term><varname>$XDG_SESSION_TYPE</varname></term>
 238
 239                                 <listitem><para>The session type. This
 240                                 may be used instead of
 241                                 <option>session=</option> on the
 242                                 module parameter line, and is usually
 243                                 preferred.</para></listitem>
 244                         </varlistentry>
 245
 246                         <varlistentry>
 247                                 <term><varname>$XDG_SESSION_CLASS</varname></term>
 248
 249                                 <listitem><para>The session class. This
 250                                 may be used instead of
 251                                 <option>class=</option> on the
 252                                 module parameter line, and is usually
 253                                 preferred.</para></listitem>
 254                         </varlistentry>
 255
 256                         <varlistentry>
 257                                 <term><varname>$XDG_SESSION_DESKTOP</varname></term>
 258
 259                                 <listitem><para>A single, short
 260                                 identifier string for the desktop
 261                                 environment. This may be used to
 262                                 indicate the session desktop used,
 263                                 where this applies and if this
 264                                 information is available. For example:
 265                                 <literal>GNOME</literal>, or
 266                                 <literal>KDE</literal>. It is
 267                                 recommended to use the same
 268                                 identifiers and capitalization as for
 269                                 <varname>$XDG_CURRENT_DESKTOP</varname>,
 270                                 as defined by the <ulink
 271                                 url="http://standards.freedesktop.org/desktop-entry-spec/latest/">Desktop
 272                                 Entry
 273                                 Specification</ulink>. See
 274                                 <citerefentry><refentrytitle>sd_session_get_desktop</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 275                                 for more details.</para></listitem>
 276                         </varlistentry>
 277
 278                         <varlistentry>
 279                                 <term><varname>$XDG_SEAT</varname></term>
 280
 281                                 <listitem><para>The seat name the session
 282                                 shall be registered for, if
 283                                 any.</para></listitem>
 284                         </varlistentry>
 285
 286                         <varlistentry>
 287                                 <term><varname>$XDG_VTNR</varname></term>
 288
 289                                 <listitem><para>The VT number the
 290                                 session shall be registered for, if
 291                                 any. (Only applies to seats with a VT
 292                                 available, such as
 293                                 <literal>seat0</literal>)</para></listitem>
 294                         </varlistentry>
 295
 296                 </variablelist>
 297         </refsect1>
 298
 299         <refsect1>
 300                 <title>Example</title>
 301
 302                 <programlisting>#%PAM-1.0
 303 auth       required     pam_unix.so
 304 auth       required     pam_nologin.so
 305 account    required     pam_unix.so
 306 password   required     pam_unix.so
 307 session    required     pam_unix.so
 308 session    required     pam_loginuid.so
 309 session    required     pam_systemd.so</programlisting>
 310         </refsect1>
 311
 312         <refsect1>
 313                 <title>See Also</title>
 314                 <para>
 315                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 316                         <citerefentry><refentrytitle>systemd-logind.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 317                         <citerefentry><refentrytitle>logind.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 318                         <citerefentry><refentrytitle>loginctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 319                         <citerefentry project='man-pages'><refentrytitle>pam.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 320                         <citerefentry project='man-pages'><refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 321                         <citerefentry project='man-pages'><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 322                         <citerefentry project='man-pages'><refentrytitle>pam_loginuid</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 323                         <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 324                         <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 325                         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 326                 </para>
 327         </refsect1>
 328
 329 </refentry>