hostap/wpa_supplicant/doc/docbook/wpa_priv.sgml

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<refentry>
  <refmeta>
    <refentrytitle>wpa_priv</refentrytitle>
    <manvolnum>8</manvolnum>
  </refmeta>
  <refnamediv>
    <refname>wpa_priv</refname>

    <refpurpose>wpa_supplicant privilege separation helper</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>wpa_priv</command>
      <arg>-c <replaceable>ctrl path</replaceable></arg>
      <arg>-Bdd</arg>
      <arg>-P <replaceable>pid file</replaceable></arg>
      <arg>driver:ifname <replaceable>[driver:ifname ...]</replaceable></arg>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Overview</title>

    <para><command>wpa_priv</command> is a privilege separation helper that
    minimizes the size of <command>wpa_supplicant</command> code that needs
    to be run with root privileges.</para>

    <para>If enabled, privileged operations are done in the wpa_priv process
    while leaving rest of the code (e.g., EAP authentication and WPA
    handshakes) to operate in an unprivileged process (wpa_supplicant) that
    can be run as non-root user. Privilege separation restricts the effects
    of potential software errors by containing the majority of the code in an
    unprivileged process to avoid the possibility of a full system
    compromise.</para>

    <para><command>wpa_priv</command> needs to be run with network admin
    privileges (usually, root user). It opens a UNIX domain socket for each
    interface that is included on the command line; any other interface will
    be off limits for <command>wpa_supplicant</command> in this kind of
    configuration. After this, <command>wpa_supplicant</command> can be run as
    a non-root user (e.g., all standard users on a laptop or as a special
    non-privileged user account created just for this purpose to limit access
    to user files even further).</para>
  </refsect1>
  <refsect1>
    <title>Example configuration</title>

    <para>The following steps are an example of how to configure
    <command>wpa_priv</command> to allow users in the
    <emphasis>wpapriv</emphasis> group to communicate with
    <command>wpa_supplicant</command> with privilege separation:</para>

    <para>Create user group (e.g., wpapriv) and assign users that
    should be able to use wpa_supplicant into that group.</para>

    <para>Create /var/run/wpa_priv directory for UNIX domain sockets and
    control user access by setting it accessible only for the wpapriv
    group:</para>

<blockquote><programlisting>
mkdir /var/run/wpa_priv
chown root:wpapriv /var/run/wpa_priv
chmod 0750 /var/run/wpa_priv
</programlisting></blockquote>

    <para>Start <command>wpa_priv</command> as root (e.g., from system
    startup scripts) with the enabled interfaces configured on the
    command line:</para>

<blockquote><programlisting>
wpa_priv -B -c /var/run/wpa_priv -P /var/run/wpa_priv.pid wext:wlan0
</programlisting></blockquote>

    <para>Run <command>wpa_supplicant</command> as non-root with a user
    that is in the wpapriv group:</para>

<blockquote><programlisting>
wpa_supplicant -i ath0 -c wpa_supplicant.conf
</programlisting></blockquote>

  </refsect1>
  <refsect1>
    <title>Command Arguments</title>
    <variablelist>
      <varlistentry>
	<term>-c ctrl path</term>

	<listitem><para>Specify the path to wpa_priv control directory
	(Default: /var/run/wpa_priv/).</para></listitem>
      </varlistentry>

      <varlistentry>
	<term>-B</term>
	<listitem><para>Run as a daemon in the background.</para></listitem>
      </varlistentry>

      <varlistentry>
	<term>-P file</term>

	<listitem><para>Set the location of the PID
	file.</para></listitem>
      </varlistentry>

      <varlistentry>
	<term>driver:ifname [driver:ifname ...]</term>

	<listitem><para>The &lt;driver&gt; string dictates which of the
	supported <command>wpa_supplicant</command> driver backends is to be
	used. To get a list of supported driver types see wpa_supplicant help
	(e.g, wpa_supplicant -h). The driver backend supported by most good
	drivers is <emphasis>wext</emphasis>.</para>

	<para>The &lt;ifname&gt; string specifies which network
	interface is to be managed by <command>wpa_supplicant</command>
	(e.g., wlan0 or ath0).</para>

	<para><command>wpa_priv</command> does not use the network interface
	before <command>wpa_supplicant</command> is started, so it is fine to
	include network interfaces that are not available at the time wpa_priv
	is started. wpa_priv can control multiple interfaces with one process,
	but it is also possible to run multiple <command>wpa_priv</command>
	processes at the same time, if desired.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>
  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry>
	<refentrytitle>wpa_supplicant</refentrytitle>
	<manvolnum>8</manvolnum>
      </citerefentry>
    </para>
  </refsect1>
  <refsect1>
    <title>Legal</title>
    <para>wpa_supplicant is copyright (c) 2003-2012,
    Jouni Malinen <email>j@w1.fi</email> and
    contributors.
    All Rights Reserved.</para>

    <para>This program is licensed under the BSD license (the one with
    advertisement clause removed).</para>
  </refsect1>
</refentry>