man/pam_systemd.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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   6   This file is part of systemd.
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   8   Copyright 2010 Lennart Poettering
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  23
  24 <refentry id="pam_systemd">
  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 control group hierarchy</refpurpose>
  48         </refnamediv>
  49
  50         <refsynopsisdiv>
  51                 <cmdsynopsis>
  52                         <command>pam_systemd.so</command>
  53                 </cmdsynopsis>
  54         </refsynopsisdiv>
  55
  56         <refsect1>
  57                 <title>Description</title>
  58
  59                 <para><command>pam_systemd</command> registers user
  60                 sessions in the systemd control group
  61                 hierarchy.</para>
  62
  63                 <para>On login, this module ensures the following:</para>
  64
  65                 <orderedlist>
  66                         <listitem><para>If it does not exist yet, the
  67                         user runtime directory
  68                         <filename>/var/run/user/$USER</filename> is
  69                         created and its ownership changed to the user
  70                         that is logging in.</para></listitem>
  71
  72                         <listitem><para>If
  73                         <option>create-session=1</option> is set, the
  74                         <varname>$XDG_SESSION_ID</varname> environment
  75                         variable is initialized. If auditing is
  76                         available and
  77                         <command>pam_loginuid.so</command> run before
  78                         this module (which is highly recommended), the
  79                         variable is initialized from the auditing
  80                         session id
  81                         (<filename>/proc/self/sessionid</filename>). Otherwise
  82                         an independent session counter is
  83                         used.</para></listitem>
  84
  85                         <listitem><para>If
  86                         <option>create-session=1</option> is set, a new
  87                         control group
  88                         <filename>/user/$USER/$XDG_SESSION_ID</filename>
  89                         is created and the login process moved into
  90                         it.</para></listitem>
  91
  92                         <listitem><para>If
  93                         <option>create-session=0</option> is set, a new
  94                         control group
  95                         <filename>/user/$USER/user</filename>
  96                         is created and the login process moved into
  97                         it.</para></listitem>
  98
  99                 </orderedlist>
 100
 101                 <para>On logout, this module ensures the following:</para>
 102
 103                 <orderedlist>
 104                         <listitem><para>If
 105                         <varname>$XDG_SESSION_ID</varname> is set and
 106                         <option>kill-session=1</option> specified, all
 107                         remaining processes in the
 108                         <filename>/user/$USER/$XDG_SESSION_ID</filename>
 109                         control group are killed and the control group
 110                         is removed.</para></listitem>
 111
 112                         <listitem><para>If
 113                         <varname>$XDG_SESSION_ID</varname> is set and
 114                         <option>kill-session=0</option> specified, all
 115                         remaining processes in the
 116                         <filename>/user/$USER/$XDG_SESSION_ID</filename>
 117                         control group are migrated to
 118                         <filename>/user/$USER/user</filename> and
 119                         the original control group is
 120                         removed.</para></listitem>
 121
 122                         <listitem><para>If
 123                         <option>kill-user=1</option> is specified, and
 124                         no other user session control group remains,
 125                         except
 126                         <filename>/user/$USER/user</filename>,
 127                         all remaining processes in the
 128                         <filename>/user/$USER</filename> hierarchy
 129                         are killed and the control group is removed.</para></listitem>
 130
 131                         <listitem><para>If
 132                         <option>kill-user=0</option> is specified, and
 133                         no process remains in the
 134                         <filename>/user/$USER</filename> hierarchy the
 135                         control group is removed.</para></listitem>
 136
 137                         <listitem><para>If the
 138                         <filename>/user/$USER</filename> control group
 139                         was removed the
 140                         <varname>$XDG_RUNTIME_DIR</varname> directory
 141                         and all its contents are
 142                         removed, too.</para></listitem>
 143                 </orderedlist>
 144
 145                 <para>If the system was not booted up with systemd as
 146                 init system, this module does nothing and immediately
 147                 returns PAM_SUCCESS.</para>
 148
 149         </refsect1>
 150
 151         <refsect1>
 152                 <title>Options</title>
 153
 154                 <para>The following options are understood:</para>
 155
 156                 <variablelist>
 157                         <varlistentry>
 158                                 <term><option>create-session=</option></term>
 159
 160                                 <listitem><para>Takes a boolean
 161                                 argument. If true, a new session is
 162                                 created: the
 163                                 <varname>$XDG_SESSION_ID</varname>
 164                                 environment variable is set and the
 165                                 login process moved to the
 166                                 <filename>/user/$USER/$XDG_SESSION_ID</filename>
 167                                 control group. It is recommended that
 168                                 all services which are directly created
 169                                 on the user's behalf set this
 170                                 option. Only for services that shall
 171                                 automatically be terminated when the
 172                                 user logs out completely, otherwise
 173                                 <varname>create-session=0</varname>
 174                                 should be set.</para></listitem>
 175                         </varlistentry>
 176
 177                         <varlistentry>
 178                                 <term><option>kill-session=</option></term>
 179
 180                                 <listitem><para>Takes a boolean
 181                                 argument. If true, all processes
 182                                 created by the user during his session
 183                                 and from his session will be
 184                                 terminated when he logs out from his
 185                                 session.</para></listitem>
 186                         </varlistentry>
 187
 188                         <varlistentry>
 189                                 <term><option>kill-user=</option></term>
 190
 191                                 <listitem><para>Takes a boolean
 192                                 argument. If true, all processes
 193                                 created by the user during his session
 194                                 and from his session will be
 195                                 terminated after he logged out
 196                                 completely. This is a weaker version
 197                                 of <option>kill-session=1</option> and is
 198                                 more friendly for users logged in more
 199                                 than once, as their processes are
 200                                 terminated only on their complete
 201                                 logout.</para></listitem>
 202                         </varlistentry>
 203
 204                         <varlistentry>
 205                                 <term><option>controllers=</option></term>
 206
 207                                 <listitem><para>Takes a comma
 208                                 seperated list of cgroup controllers
 209                                 in which hierarchies a user/session
 210                                 cgroup will be created by defautl for
 211                                 each user logging in. If ommited,
 212                                 defaults to 'cpu', meaning that in
 213                                 addition to creating per-user and
 214                                 per-session cgroups in systemd's own
 215                                 hierarchy, groups are created in the
 216                                 'cpu' hierarchy, on order to ensure
 217                                 that every use and every sessions gets
 218                                 an equal amount of CPU time,
 219                                 regardless how many processes a user
 220                                 or session might
 221                                 own.</para></listitem>
 222                         </varlistentry>
 223                 </variablelist>
 224
 225                 <para>Note that setting <varname>kill-user=1</varname>
 226                 or even <varname>kill-session=1</varname> will break
 227                 tools like
 228                 <citerefentry><refentrytitle>screen</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
 229
 230                 <para>If the options are omitted they default to
 231                 <option>create-session=1</option>,
 232                 <option>kill-session=0</option>,
 233                 <option>kill-user=0</option>.</para>
 234         </refsect1>
 235
 236         <refsect1>
 237                 <title>Module Types Provided</title>
 238
 239                 <para>Only <option>session</option> is provided.</para>
 240         </refsect1>
 241
 242         <refsect1>
 243                 <title>Environment</title>
 244
 245                 <para>The following environment variables are set for the processes of the user's session:</para>
 246
 247                 <variablelist>
 248                         <varlistentry>
 249                                 <term><varname>$XDG_SESSION_ID</varname></term>
 250
 251                                 <listitem><para>A session identifier,
 252                                 suitable to be used in file names. The
 253                                 string itself should be considered
 254                                 opaque, although often it is just the
 255                                 audit session ID as reported by
 256                                 <filename>/proc/self/sessionid</filename>. Each
 257                                 ID will be assigned only once during
 258                                 machine uptime. It may hence be used
 259                                 to uniquely label files or other
 260                                 resources of this
 261                                 session.</para></listitem>
 262                         </varlistentry>
 263
 264                         <varlistentry>
 265                                 <term><varname>$XDG_RUNTIME_DIR</varname></term>
 266
 267                                 <listitem><para>Path to a user-private
 268                                 user-writable directory that is bound
 269                                 to the user login time on the
 270                                 machine. It is automatically created
 271                                 the first time a user logs in and
 272                                 removed on his final logout. If a user
 273                                 logs in twice at the same time, both
 274                                 sessions will see the same
 275                                 <varname>$XDG_RUNTIME_DIR</varname>
 276                                 and the same contents. If a user logs
 277                                 in once, then logs out again, and logs
 278                                 in again, the directory contents will
 279                                 have been lost in between, but
 280                                 applications should not rely on this
 281                                 behaviour and must be able to deal with
 282                                 stale files. To store session-private
 283                                 data in this directory the user should
 284                                 include the value of <varname>$XDG_SESSION_ID</varname>
 285                                 in the filename. This directory shall
 286                                 be used for runtime file system
 287                                 objects such as AF_UNIX sockets,
 288                                 FIFOs, PID files and similar. It is
 289                                 guaranteed that this directory is
 290                                 local and offers the greatest possible
 291                                 file system feature set the
 292                                 operating system
 293                                 provides.</para></listitem>
 294                         </varlistentry>
 295                 </variablelist>
 296         </refsect1>
 297
 298         <refsect1>
 299                 <title>Example</title>
 300
 301                 <programlisting>#%PAM-1.0
 302 auth       required     pam_unix.so
 303 auth       required     pam_nologin.so
 304 account    required     pam_unix.so
 305 password   required     pam_unix.so
 306 session    required     pam_unix.so
 307 session    required     pam_loginuid.so
 308 session    required     pam_systemd.so kill-user=1</programlisting>
 309         </refsect1>
 310
 311         <refsect1>
 312                 <title>See Also</title>
 313                 <para>
 314                         <citerefentry><refentrytitle>pam.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 315                         <citerefentry><refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 316                         <citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 317                         <citerefentry><refentrytitle>pam_loginuid</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 318                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 319                 </para>
 320         </refsect1>
 321
 322 </refentry>