1 <?xml version='1.0'?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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6 This file is part of systemd.
8 Copyright 2010 Lennart Poettering
10 systemd is free software; you can redistribute it and/or modify it
11 under the terms of the GNU General Public License as published by
12 the Free Software Foundation; either version 2 of the License, or
13 (at your option) any later version.
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 General Public License for more details.
20 You should have received a copy of the GNU General Public License
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24 <refentry id="pam_systemd">
27 <title>pam_systemd</title>
28 <productname>systemd</productname>
32 <contrib>Developer</contrib>
33 <firstname>Lennart</firstname>
34 <surname>Poettering</surname>
35 <email>lennart@poettering.net</email>
41 <refentrytitle>pam_systemd</refentrytitle>
42 <manvolnum>8</manvolnum>
46 <refname>pam_systemd</refname>
47 <refpurpose>Register user sessions in the systemd control group hierarchy</refpurpose>
52 <command>pam_systemd.so</command>
57 <title>Description</title>
59 <para><command>pam_systemd</command> registers user
60 sessions in the systemd control group
63 <para>On login, this module ensures the following:</para>
66 <listitem><para>If it does not exist yet, the
67 user runtime directory
68 <filename>/run/user/$USER</filename> is
69 created and its ownership changed to the user
70 that is logging in.</para></listitem>
73 <option>create-session=1</option> is set, the
74 <varname>$XDG_SESSION_ID</varname> environment
75 variable is initialized. If auditing is
77 <command>pam_loginuid.so</command> run before
78 this module (which is highly recommended), the
79 variable is initialized from the auditing
81 (<filename>/proc/self/sessionid</filename>). Otherwise
82 an independent session counter is
83 used.</para></listitem>
86 <option>create-session=1</option> is set, a new
88 <filename>/user/$USER/$XDG_SESSION_ID</filename>
89 is created and the login process moved into
93 <option>create-session=0</option> is set, a new
95 <filename>/user/$USER/user</filename>
96 is created and the login process moved into
101 <para>On logout, this module ensures the following:</para>
105 <varname>$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>
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>
123 <option>kill-user=1</option> is specified, and
124 no other user session control group remains,
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>
132 <option>kill-user=0</option> is specified, and
133 no process remains in the
134 <filename>/user/$USER</filename> hierarchy the
135 control group is removed.</para></listitem>
137 <listitem><para>If the
138 <filename>/user/$USER</filename> control group
140 <varname>$XDG_RUNTIME_DIR</varname> directory
141 and all its contents are
142 removed, too.</para></listitem>
145 <para>If the system was not booted up with systemd as
146 init system, this module does nothing and immediately
147 returns PAM_SUCCESS.</para>
152 <title>Options</title>
154 <para>The following options are understood:</para>
158 <term><option>create-session=</option></term>
160 <listitem><para>Takes a boolean
161 argument. If true, a new session is
163 <varname>$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>
178 <term><option>kill-session=</option></term>
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>
189 <term><option>kill-user=</option></term>
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>
205 <term><option>kill-only-users=</option></term>
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
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>
224 <term><option>kill-exclude-users=</option></term>
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
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
241 setting.</para></listitem>
245 <term><option>controllers=</option></term>
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 omitted, 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
260 started.</para></listitem>
264 <term><option>reset-controllers=</option></term>
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 omitted, 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>
278 <term><option>debug=</option></term>
280 <listitem><para>Takes a boolean
281 argument. If true, logs debugging
282 information.</para></listitem>
286 <para>Note that setting <varname>kill-user=1</varname>
287 or even <varname>kill-session=1</varname> will break
289 <citerefentry><refentrytitle>screen</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
291 <para>If the options are omitted they default to
292 <option>create-session=1</option>,
293 <option>kill-session=0</option>,
294 <option>kill-user=0</option>,
295 <option>reset-controllers=cpu</option>,
296 <option>kill-only-users=</option>,
297 <option>kill-exclude-users=root</option>.</para>
301 <title>Module Types Provided</title>
303 <para>Only <option>session</option> is provided.</para>
307 <title>Environment</title>
309 <para>The following environment variables are set for the processes of the user's session:</para>
313 <term><varname>$XDG_SESSION_ID</varname></term>
315 <listitem><para>A session identifier,
316 suitable to be used in file names. The
317 string itself should be considered
318 opaque, although often it is just the
319 audit session ID as reported by
320 <filename>/proc/self/sessionid</filename>. Each
321 ID will be assigned only once during
322 machine uptime. It may hence be used
323 to uniquely label files or other
325 session.</para></listitem>
329 <term><varname>$XDG_RUNTIME_DIR</varname></term>
331 <listitem><para>Path to a user-private
332 user-writable directory that is bound
333 to the user login time on the
334 machine. It is automatically created
335 the first time a user logs in and
336 removed on his final logout. If a user
337 logs in twice at the same time, both
338 sessions will see the same
339 <varname>$XDG_RUNTIME_DIR</varname>
340 and the same contents. If a user logs
341 in once, then logs out again, and logs
342 in again, the directory contents will
343 have been lost in between, but
344 applications should not rely on this
345 behaviour and must be able to deal with
346 stale files. To store session-private
347 data in this directory the user should
348 include the value of <varname>$XDG_SESSION_ID</varname>
349 in the filename. This directory shall
350 be used for runtime file system
351 objects such as AF_UNIX sockets,
352 FIFOs, PID files and similar. It is
353 guaranteed that this directory is
354 local and offers the greatest possible
355 file system feature set the
357 provides.</para></listitem>
363 <title>Example</title>
365 <programlisting>#%PAM-1.0
366 auth required pam_unix.so
367 auth required pam_nologin.so
368 account required pam_unix.so
369 password required pam_unix.so
370 session required pam_unix.so
371 session required pam_loginuid.so
372 session required pam_systemd.so kill-user=1</programlisting>
376 <title>See Also</title>
378 <citerefentry><refentrytitle>pam.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
379 <citerefentry><refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
380 <citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
381 <citerefentry><refentrytitle>pam_loginuid</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
382 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>