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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.
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
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18 General Public License for more details.
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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>/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. If ommited,
226 defaults to 'cpu', meaning that in
227 addition to creating per-user and
228 per-session cgroups in systemd's own
229 hierarchy, groups are created in the
230 'cpu' hierarchy, on order to ensure
231 that every use and every sessions gets
232 an equal amount of CPU time,
233 regardless how many processes a user
235 own.</para></listitem>
239 <para>Note that setting <varname>kill-user=1</varname>
240 or even <varname>kill-session=1</varname> will break
242 <citerefentry><refentrytitle>screen</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
244 <para>If the options are omitted they default to
245 <option>create-session=1</option>,
246 <option>kill-session=0</option>,
247 <option>kill-user=0</option>,
248 <option>keep-root=1</option>.</para>
252 <title>Module Types Provided</title>
254 <para>Only <option>session</option> is provided.</para>
258 <title>Environment</title>
260 <para>The following environment variables are set for the processes of the user's session:</para>
264 <term><varname>$XDG_SESSION_ID</varname></term>
266 <listitem><para>A session identifier,
267 suitable to be used in file names. The
268 string itself should be considered
269 opaque, although often it is just the
270 audit session ID as reported by
271 <filename>/proc/self/sessionid</filename>. Each
272 ID will be assigned only once during
273 machine uptime. It may hence be used
274 to uniquely label files or other
276 session.</para></listitem>
280 <term><varname>$XDG_RUNTIME_DIR</varname></term>
282 <listitem><para>Path to a user-private
283 user-writable directory that is bound
284 to the user login time on the
285 machine. It is automatically created
286 the first time a user logs in and
287 removed on his final logout. If a user
288 logs in twice at the same time, both
289 sessions will see the same
290 <varname>$XDG_RUNTIME_DIR</varname>
291 and the same contents. If a user logs
292 in once, then logs out again, and logs
293 in again, the directory contents will
294 have been lost in between, but
295 applications should not rely on this
296 behaviour and must be able to deal with
297 stale files. To store session-private
298 data in this directory the user should
299 include the value of <varname>$XDG_SESSION_ID</varname>
300 in the filename. This directory shall
301 be used for runtime file system
302 objects such as AF_UNIX sockets,
303 FIFOs, PID files and similar. It is
304 guaranteed that this directory is
305 local and offers the greatest possible
306 file system feature set the
308 provides.</para></listitem>
314 <title>Example</title>
316 <programlisting>#%PAM-1.0
317 auth required pam_unix.so
318 auth required pam_nologin.so
319 account required pam_unix.so
320 password required pam_unix.so
321 session required pam_unix.so
322 session required pam_loginuid.so
323 session required pam_systemd.so kill-user=1</programlisting>
327 <title>See Also</title>
329 <citerefentry><refentrytitle>pam.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
330 <citerefentry><refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
331 <citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
332 <citerefentry><refentrytitle>pam_loginuid</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
333 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>