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
21 along with systemd; If not, see <http://www.gnu.org/licenses/>.
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>/var/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 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
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 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>
278 <para>Note that setting <varname>kill-user=1</varname>
279 or even <varname>kill-session=1</varname> will break
281 <citerefentry><refentrytitle>screen</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
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>keep-root=1</option>,
288 <option>reset-controllers=cpu</option>,
289 <option>kill-only-users=</option>,
290 <option>kill-exclude-users=root</option>.</para>
294 <title>Module Types Provided</title>
296 <para>Only <option>session</option> is provided.</para>
300 <title>Environment</title>
302 <para>The following environment variables are set for the processes of the user's session:</para>
306 <term><varname>$XDG_SESSION_ID</varname></term>
308 <listitem><para>A session identifier,
309 suitable to be used in file names. The
310 string itself should be considered
311 opaque, although often it is just the
312 audit session ID as reported by
313 <filename>/proc/self/sessionid</filename>. Each
314 ID will be assigned only once during
315 machine uptime. It may hence be used
316 to uniquely label files or other
318 session.</para></listitem>
322 <term><varname>$XDG_RUNTIME_DIR</varname></term>
324 <listitem><para>Path to a user-private
325 user-writable directory that is bound
326 to the user login time on the
327 machine. It is automatically created
328 the first time a user logs in and
329 removed on his final logout. If a user
330 logs in twice at the same time, both
331 sessions will see the same
332 <varname>$XDG_RUNTIME_DIR</varname>
333 and the same contents. If a user logs
334 in once, then logs out again, and logs
335 in again, the directory contents will
336 have been lost in between, but
337 applications should not rely on this
338 behaviour and must be able to deal with
339 stale files. To store session-private
340 data in this directory the user should
341 include the value of <varname>$XDG_SESSION_ID</varname>
342 in the filename. This directory shall
343 be used for runtime file system
344 objects such as AF_UNIX sockets,
345 FIFOs, PID files and similar. It is
346 guaranteed that this directory is
347 local and offers the greatest possible
348 file system feature set the
350 provides.</para></listitem>
356 <title>Example</title>
358 <programlisting>#%PAM-1.0
359 auth required pam_unix.so
360 auth required pam_nologin.so
361 account required pam_unix.so
362 password required pam_unix.so
363 session required pam_unix.so
364 session required pam_loginuid.so
365 session required pam_systemd.so kill-user=1</programlisting>
369 <title>See Also</title>
371 <citerefentry><refentrytitle>pam.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
372 <citerefentry><refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
373 <citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
374 <citerefentry><refentrytitle>pam_loginuid</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
375 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>