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.
   7
   8   Copyright 2010 Lennart Poettering
   9
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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>/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>kill-only-users=</option></term>
 206
 207                                 <listitem><para>Takes a comma
 208                                 separated list of user names or
 209                                 numeric user ids as argument. If this
 210                                 option is used the effect of the
 211                                 <option>kill-session=</option> and
 212                                 <option>kill-user=</option> options
 213                                 will apply only to the listed
 214                                 users. If this option is not used the
 215                                 option applies to all local
 216                                 users. Note that
 217                                 <option>kill-exclude-users=</option>
 218                                 takes precedence over this list and is
 219                                 hence subtracted from the list
 220                                 specified here.</para></listitem>
 221                         </varlistentry>
 222
 223                         <varlistentry>
 224                                 <term><option>kill-exclude-users=</option></term>
 225
 226                                 <listitem><para>Takes a comma
 227                                 separated list of user names or
 228                                 numeric user ids as argument. Users
 229                                 listed in this argument will not be
 230                                 subject to the effect of
 231                                 <option>kill-session=</option> or
 232                                 <option>kill-user=</option>.  Note
 233                                 that that this option takes precedence
 234                                 over
 235                                 <option>kill-only-users=</option>, and
 236                                 hence whatever is listed for
 237                                 <option>kill-exclude-users=</option>
 238                                 is guaranteed to never be killed by
 239                                 this PAM module, independent of any
 240                                 other configuration
 241                                 setting.</para></listitem>
 242                         </varlistentry>
 243
 244                         <varlistentry>
 245                                 <term><option>controllers=</option></term>
 246
 247                                 <listitem><para>Takes a comma
 248                                 separated list of cgroup controllers
 249                                 in which hierarchies a user/session
 250                                 cgroup will be created by default for
 251                                 each user logging in, in addition to
 252                                 the cgroup in the named 'name=systemd'
 253                                 hierarchy. If ommited, defaults to an
 254                                 empty list. This may be used to move
 255                                 user sessions into their own groups in
 256                                 the 'cpu' hierarchy which ensures that
 257                                 every logged in user gets an equal
 258                                 amount of CPU time regardless how many
 259                                 processes he has
 260                                 started.</para></listitem>
 261                         </varlistentry>
 262
 263                         <varlistentry>
 264                                 <term><option>reset-controllers=</option></term>
 265
 266                                 <listitem><para>Takes a comma
 267                                 separated list of cgroup controllers
 268                                 in which hierarchies the logged in
 269                                 processes will be reset to the root
 270                                 cgroup. If ommited, defaults to 'cpu',
 271                                 meaning that a 'cpu' cgroup grouping
 272                                 inherited from the login manager will
 273                                 be reset for the processes of the
 274                                 logged in user.</para></listitem>
 275                         </varlistentry>
 276                 </variablelist>
 277
 278                 <para>Note that setting <varname>kill-user=1</varname>
 279                 or even <varname>kill-session=1</varname> will break
 280                 tools like
 281                 <citerefentry><refentrytitle>screen</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
 282
 283                 <para>If the options are omitted they default to
 284                 <option>create-session=1</option>,
 285                 <option>kill-session=0</option>,
 286                 <option>kill-user=0</option>,
 287                 <option>reset-controllers=cpu</option>,
 288                 <option>kill-only-users=</option>,
 289                 <option>kill-exclude-users=root</option>.</para>
 290         </refsect1>
 291
 292         <refsect1>
 293                 <title>Module Types Provided</title>
 294
 295                 <para>Only <option>session</option> is provided.</para>
 296         </refsect1>
 297
 298         <refsect1>
 299                 <title>Environment</title>
 300
 301                 <para>The following environment variables are set for the processes of the user's session:</para>
 302
 303                 <variablelist>
 304                         <varlistentry>
 305                                 <term><varname>$XDG_SESSION_ID</varname></term>
 306
 307                                 <listitem><para>A session identifier,
 308                                 suitable to be used in file names. The
 309                                 string itself should be considered
 310                                 opaque, although often it is just the
 311                                 audit session ID as reported by
 312                                 <filename>/proc/self/sessionid</filename>. Each
 313                                 ID will be assigned only once during
 314                                 machine uptime. It may hence be used
 315                                 to uniquely label files or other
 316                                 resources of this
 317                                 session.</para></listitem>
 318                         </varlistentry>
 319
 320                         <varlistentry>
 321                                 <term><varname>$XDG_RUNTIME_DIR</varname></term>
 322
 323                                 <listitem><para>Path to a user-private
 324                                 user-writable directory that is bound
 325                                 to the user login time on the
 326                                 machine. It is automatically created
 327                                 the first time a user logs in and
 328                                 removed on his final logout. If a user
 329                                 logs in twice at the same time, both
 330                                 sessions will see the same
 331                                 <varname>$XDG_RUNTIME_DIR</varname>
 332                                 and the same contents. If a user logs
 333                                 in once, then logs out again, and logs
 334                                 in again, the directory contents will
 335                                 have been lost in between, but
 336                                 applications should not rely on this
 337                                 behaviour and must be able to deal with
 338                                 stale files. To store session-private
 339                                 data in this directory the user should
 340                                 include the value of <varname>$XDG_SESSION_ID</varname>
 341                                 in the filename. This directory shall
 342                                 be used for runtime file system
 343                                 objects such as AF_UNIX sockets,
 344                                 FIFOs, PID files and similar. It is
 345                                 guaranteed that this directory is
 346                                 local and offers the greatest possible
 347                                 file system feature set the
 348                                 operating system
 349                                 provides.</para></listitem>
 350                         </varlistentry>
 351                 </variablelist>
 352         </refsect1>
 353
 354         <refsect1>
 355                 <title>Example</title>
 356
 357                 <programlisting>#%PAM-1.0
 358 auth       required     pam_unix.so
 359 auth       required     pam_nologin.so
 360 account    required     pam_unix.so
 361 password   required     pam_unix.so
 362 session    required     pam_unix.so
 363 session    required     pam_loginuid.so
 364 session    required     pam_systemd.so kill-user=1</programlisting>
 365         </refsect1>
 366
 367         <refsect1>
 368                 <title>See Also</title>
 369                 <para>
 370                         <citerefentry><refentrytitle>pam.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 371                         <citerefentry><refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 372                         <citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 373                         <citerefentry><refentrytitle>pam_loginuid</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 374                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 375                 </para>
 376         </refsect1>
 377
 378 </refentry>