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/$USER/no-session</filename>
96 is created and the login process moved into
101 <para>On logout, this module ensures the following:</para>
105 <varname>$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/no-session</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/$USER/no-session</filename>,
127 all remaining processes in the
128 <filename>/user/$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 <para>Note that setting <varname>kill-user=1</varname>
206 or even <varname>kill-session=1</varname> will break
208 <citerefentry><refentrytitle>screen</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
210 <para>If the options are omitted they default to
211 <option>create-session=1</option>,
212 <option>kill-session=0</option>,
213 <option>kill-user=0</option>.</para>
217 <title>Module Types Provided</title>
219 <para>Only <option>session</option> is provided.</para>
223 <title>Environment</title>
225 <para>The following environment variables are set for the processes of the user's session:</para>
229 <term><varname>$XDG_SESSION_ID</varname></term>
231 <listitem><para>A session identifier,
232 suitable to be used in file names. The
233 string itself should be considered
234 opaque, although often it is just the
235 audit session ID as reported by
236 <filename>/proc/self/sessionid</filename>. Each
237 ID will be assigned only once during
238 machine uptime. It may hence be used
239 to uniquely label files or other
241 session.</para></listitem>
245 <term><varname>$XDG_RUNTIME_DIR</varname></term>
247 <listitem><para>Path to a user-private
248 user-writable directory that is bound
249 to the user login time on the
250 machine. It is automatically created
251 the first time a user logs in and
252 removed on his final logout. If a user
253 logs in twice at the same time, both
254 sessions will see the same
255 <varname>$XDG_RUNTIME_DIR</varname>
256 and the same contents. If a user logs
257 in once, then logs out again, and logs
258 in again, the directory contents will
259 have been lost in between, but
260 applications should not rely on this
261 behaviour and must be able to deal with
262 stale files. To store session-private
263 data in this directory the user should
264 include the value of <varname>$XDG_SESSION_ID</varname>
265 in the filename. This directory shall
266 be used for runtime file system
267 objects such as AF_UNIX sockets,
268 FIFOs, PID files and similar. It is
269 guaranteed that this directory is
270 local and offers the greatest possible
271 file system feature set the
273 provides.</para></listitem>
279 <title>Example</title>
281 <programlisting>#%PAM-1.0
282 auth required pam_unix.so
283 auth required pam_nologin.so
284 account required pam_unix.so
285 password required pam_unix.so
286 session required pam_unix.so
287 session required pam_loginuid.so
288 session required pam_systemd.so kill-user=1</programlisting>
292 <title>See Also</title>
294 <citerefentry><refentrytitle>pam.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
295 <citerefentry><refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
296 <citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
297 <citerefentry><refentrytitle>pam_loginuid</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
298 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>