1 <?xml version='1.0'?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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>keep-root=</option></term>
207 <listitem><para>Takes a boolean
208 argument. If true, all processes
209 created by the root user (UID 0) during his
210 session and from his session will be
211 kept around after he logged out. This
212 option allows cancelling the effect of
213 <option>kill-session=1</option> and
214 <option>kill-user=1</option> for the
215 root user.</para></listitem>
219 <term><option>controllers=</option></term>
221 <listitem><para>Takes a comma
222 separated list of cgroup controllers
223 in which hierarchies a user/session
224 cgroup will be created by default for
225 each user logging in, in addition to
226 the cgroup in the named 'name=systemd'
227 hierarchy. If ommited, defaults to an
228 empty list. This may be used to move
229 user sessions into their own groups in
230 the 'cpu' hierarchy which ensures that
231 every logged in user gets an equal
232 amount of CPU time regardless how many
234 started.</para></listitem>
238 <term><option>reset-controllers=</option></term>
240 <listitem><para>Takes a comma
241 separated list of cgroup controllers
242 in which hierarchies the logged in
243 processes will be reset to the root
244 cgroup. If ommited, defaults to 'cpu',
245 meaning that a 'cpu' cgroup grouping
246 inherited from the login manager will
247 be reset for the processes of the
248 logged in user.</para></listitem>
252 <para>Note that setting <varname>kill-user=1</varname>
253 or even <varname>kill-session=1</varname> will break
255 <citerefentry><refentrytitle>screen</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
257 <para>If the options are omitted they default to
258 <option>create-session=1</option>,
259 <option>kill-session=0</option>,
260 <option>kill-user=0</option>,
261 <option>keep-root=1</option>,
262 <option>reset-controllers=cpu</option>.</para>
266 <title>Module Types Provided</title>
268 <para>Only <option>session</option> is provided.</para>
272 <title>Environment</title>
274 <para>The following environment variables are set for the processes of the user's session:</para>
278 <term><varname>$XDG_SESSION_ID</varname></term>
280 <listitem><para>A session identifier,
281 suitable to be used in file names. The
282 string itself should be considered
283 opaque, although often it is just the
284 audit session ID as reported by
285 <filename>/proc/self/sessionid</filename>. Each
286 ID will be assigned only once during
287 machine uptime. It may hence be used
288 to uniquely label files or other
290 session.</para></listitem>
294 <term><varname>$XDG_RUNTIME_DIR</varname></term>
296 <listitem><para>Path to a user-private
297 user-writable directory that is bound
298 to the user login time on the
299 machine. It is automatically created
300 the first time a user logs in and
301 removed on his final logout. If a user
302 logs in twice at the same time, both
303 sessions will see the same
304 <varname>$XDG_RUNTIME_DIR</varname>
305 and the same contents. If a user logs
306 in once, then logs out again, and logs
307 in again, the directory contents will
308 have been lost in between, but
309 applications should not rely on this
310 behaviour and must be able to deal with
311 stale files. To store session-private
312 data in this directory the user should
313 include the value of <varname>$XDG_SESSION_ID</varname>
314 in the filename. This directory shall
315 be used for runtime file system
316 objects such as AF_UNIX sockets,
317 FIFOs, PID files and similar. It is
318 guaranteed that this directory is
319 local and offers the greatest possible
320 file system feature set the
322 provides.</para></listitem>
328 <title>Example</title>
330 <programlisting>#%PAM-1.0
331 auth required pam_unix.so
332 auth required pam_nologin.so
333 account required pam_unix.so
334 password required pam_unix.so
335 session required pam_unix.so
336 session required pam_loginuid.so
337 session required pam_systemd.so kill-user=1</programlisting>
341 <title>See Also</title>
343 <citerefentry><refentrytitle>pam.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
344 <citerefentry><refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
345 <citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
346 <citerefentry><refentrytitle>pam_loginuid</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
347 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>