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systemd/man/pam_systemd.xml
Lennart Poettering bb29785e0d general: replace a few uses of /var/run by /run
2011-04-01 15:25:46 +02:00

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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
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Copyright 2010 Lennart Poettering
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<refentry id="pam_systemd">
<refentryinfo>
<title>pam_systemd</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>pam_systemd</refentrytitle>
<manvolnum>8</manvolnum>
</refmeta>
<refnamediv>
<refname>pam_systemd</refname>
<refpurpose>Register user sessions in the systemd control group hierarchy</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>pam_systemd.so</command>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><command>pam_systemd</command> registers user
sessions in the systemd control group
hierarchy.</para>
<para>On login, this module ensures the following:</para>
<orderedlist>
<listitem><para>If it does not exist yet, the
user runtime directory
<filename>/run/user/$USER</filename> is
created and its ownership changed to the user
that is logging in.</para></listitem>
<listitem><para>If
<option>create-session=1</option> is set, the
<varname>$XDG_SESSION_ID</varname> environment
variable is initialized. If auditing is
available and
<command>pam_loginuid.so</command> run before
this module (which is highly recommended), the
variable is initialized from the auditing
session id
(<filename>/proc/self/sessionid</filename>). Otherwise
an independent session counter is
used.</para></listitem>
<listitem><para>If
<option>create-session=1</option> is set, a new
control group
<filename>/user/$USER/$XDG_SESSION_ID</filename>
is created and the login process moved into
it.</para></listitem>
<listitem><para>If
<option>create-session=0</option> is set, a new
control group
<filename>/user/$USER/user</filename>
is created and the login process moved into
it.</para></listitem>
</orderedlist>
<para>On logout, this module ensures the following:</para>
<orderedlist>
<listitem><para>If
<varname>$XDG_SESSION_ID</varname> is set and
<option>kill-session=1</option> specified, all
remaining processes in the
<filename>/user/$USER/$XDG_SESSION_ID</filename>
control group are killed and the control group
is removed.</para></listitem>
<listitem><para>If
<varname>$XDG_SESSION_ID</varname> is set and
<option>kill-session=0</option> specified, all
remaining processes in the
<filename>/user/$USER/$XDG_SESSION_ID</filename>
control group are migrated to
<filename>/user/$USER/user</filename> and
the original control group is
removed.</para></listitem>
<listitem><para>If
<option>kill-user=1</option> is specified, and
no other user session control group remains,
except
<filename>/user/$USER/user</filename>,
all remaining processes in the
<filename>/user/$USER</filename> hierarchy
are killed and the control group is removed.</para></listitem>
<listitem><para>If
<option>kill-user=0</option> is specified, and
no process remains in the
<filename>/user/$USER</filename> hierarchy the
control group is removed.</para></listitem>
<listitem><para>If the
<filename>/user/$USER</filename> control group
was removed the
<varname>$XDG_RUNTIME_DIR</varname> directory
and all its contents are
removed, too.</para></listitem>
</orderedlist>
<para>If the system was not booted up with systemd as
init system, this module does nothing and immediately
returns PAM_SUCCESS.</para>
</refsect1>
<refsect1>
<title>Options</title>
<para>The following options are understood:</para>
<variablelist>
<varlistentry>
<term><option>create-session=</option></term>
<listitem><para>Takes a boolean
argument. If true, a new session is
created: the
<varname>$XDG_SESSION_ID</varname>
environment variable is set and the
login process moved to the
<filename>/user/$USER/$XDG_SESSION_ID</filename>
control group. It is recommended that
all services which are directly created
on the user's behalf set this
option. Only for services that shall
automatically be terminated when the
user logs out completely, otherwise
<varname>create-session=0</varname>
should be set.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>kill-session=</option></term>
<listitem><para>Takes a boolean
argument. If true, all processes
created by the user during his session
and from his session will be
terminated when he logs out from his
session.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>kill-user=</option></term>
<listitem><para>Takes a boolean
argument. If true, all processes
created by the user during his session
and from his session will be
terminated after he logged out
completely. This is a weaker version
of <option>kill-session=1</option> and is
more friendly for users logged in more
than once, as their processes are
terminated only on their complete
logout.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>kill-only-users=</option></term>
<listitem><para>Takes a comma
separated list of user names or
numeric user ids as argument. If this
option is used the effect of the
<option>kill-session=</option> and
<option>kill-user=</option> options
will apply only to the listed
users. If this option is not used the
option applies to all local
users. Note that
<option>kill-exclude-users=</option>
takes precedence over this list and is
hence subtracted from the list
specified here.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>kill-exclude-users=</option></term>
<listitem><para>Takes a comma
separated list of user names or
numeric user ids as argument. Users
listed in this argument will not be
subject to the effect of
<option>kill-session=</option> or
<option>kill-user=</option>. Note
that that this option takes precedence
over
<option>kill-only-users=</option>, and
hence whatever is listed for
<option>kill-exclude-users=</option>
is guaranteed to never be killed by
this PAM module, independent of any
other configuration
setting.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>controllers=</option></term>
<listitem><para>Takes a comma
separated list of cgroup controllers
in which hierarchies a user/session
cgroup will be created by default for
each user logging in, in addition to
the cgroup in the named 'name=systemd'
hierarchy. If ommited, defaults to an
empty list. This may be used to move
user sessions into their own groups in
the 'cpu' hierarchy which ensures that
every logged in user gets an equal
amount of CPU time regardless how many
processes he has
started.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>reset-controllers=</option></term>
<listitem><para>Takes a comma
separated list of cgroup controllers
in which hierarchies the logged in
processes will be reset to the root
cgroup. If ommited, defaults to 'cpu',
meaning that a 'cpu' cgroup grouping
inherited from the login manager will
be reset for the processes of the
logged in user.</para></listitem>
</varlistentry>
</variablelist>
<para>Note that setting <varname>kill-user=1</varname>
or even <varname>kill-session=1</varname> will break
tools like
<citerefentry><refentrytitle>screen</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
<para>If the options are omitted they default to
<option>create-session=1</option>,
<option>kill-session=0</option>,
<option>kill-user=0</option>,
<option>reset-controllers=cpu</option>,
<option>kill-only-users=</option>,
<option>kill-exclude-users=root</option>.</para>
</refsect1>
<refsect1>
<title>Module Types Provided</title>
<para>Only <option>session</option> is provided.</para>
</refsect1>
<refsect1>
<title>Environment</title>
<para>The following environment variables are set for the processes of the user's session:</para>
<variablelist>
<varlistentry>
<term><varname>$XDG_SESSION_ID</varname></term>
<listitem><para>A session identifier,
suitable to be used in file names. The
string itself should be considered
opaque, although often it is just the
audit session ID as reported by
<filename>/proc/self/sessionid</filename>. Each
ID will be assigned only once during
machine uptime. It may hence be used
to uniquely label files or other
resources of this
session.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>$XDG_RUNTIME_DIR</varname></term>
<listitem><para>Path to a user-private
user-writable directory that is bound
to the user login time on the
machine. It is automatically created
the first time a user logs in and
removed on his final logout. If a user
logs in twice at the same time, both
sessions will see the same
<varname>$XDG_RUNTIME_DIR</varname>
and the same contents. If a user logs
in once, then logs out again, and logs
in again, the directory contents will
have been lost in between, but
applications should not rely on this
behaviour and must be able to deal with
stale files. To store session-private
data in this directory the user should
include the value of <varname>$XDG_SESSION_ID</varname>
in the filename. This directory shall
be used for runtime file system
objects such as AF_UNIX sockets,
FIFOs, PID files and similar. It is
guaranteed that this directory is
local and offers the greatest possible
file system feature set the
operating system
provides.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Example</title>
<programlisting>#%PAM-1.0
auth required pam_unix.so
auth required pam_nologin.so
account required pam_unix.so
password required pam_unix.so
session required pam_unix.so
session required pam_loginuid.so
session required pam_systemd.so kill-user=1</programlisting>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>pam.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>pam_loginuid</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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