/mandos/trunk

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
	"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
<!ENTITY COMMANDNAME "password-agent">
<!ENTITY TIMESTAMP "2019-07-24">
<!ENTITY % common SYSTEM "../common.ent">
%common;
]>

<refentry xmlns:xi="http://www.w3.org/2001/XInclude">
  <refentryinfo>
    <title>Mandos Manual</title>
    <!-- Nwalsh’s docbook scripts use this to generate the footer: -->
    <productname>Mandos</productname>
    <productnumber>&version;</productnumber>
    <date>&TIMESTAMP;</date>
    <authorgroup>
      <author>
	<firstname>Björn</firstname>
	<surname>Påhlsson</surname>
	<address>
	  <email>belorn@recompile.se</email>
	</address>
      </author>
      <author>
	<firstname>Teddy</firstname>
	<surname>Hogeborn</surname>
	<address>
	  <email>teddy@recompile.se</email>
	</address>
      </author>
    </authorgroup>
    <copyright>
      <year>2019</year>
      <holder>Teddy Hogeborn</holder>
      <holder>Björn Påhlsson</holder>
    </copyright>
    <xi:include href="../legalnotice.xml"/>
  </refentryinfo>

  <refmeta>
    <refentrytitle>&COMMANDNAME;</refentrytitle>
    <manvolnum>8mandos</manvolnum>
  </refmeta>

  <refnamediv>
    <refname><command>&COMMANDNAME;</command></refname>
    <refpurpose>
      Run Mandos client as a systemd password agent.
    </refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>&COMMANDNAME;</command>
      <arg><option>--agent-directory=<replaceable
      >DIRECTORY</replaceable></option></arg>
      <sbr/>
      <arg><option>--helper-directory=<replaceable
      >DIRECTORY</replaceable></option></arg>
      <sbr/>
      <!-- <arg><option>-\-plugin-helper-dir=<replaceable -->
      <!-- >DIRECTORY</replaceable></option></arg> -->
      <!-- <sbr/> -->
      <arg><option>--user=<replaceable
      >USERID</replaceable></option></arg>
      <sbr/>
      <!-- <arg><option>-\-userid=<replaceable -->
      <!-- >ID</replaceable></option></arg> -->
      <!-- <sbr/> -->
      <arg><option>--group=<replaceable
      >GROUPID</replaceable></option></arg>
      <sbr/>
      <!-- <arg><option>-\-groupid=<replaceable -->
      <!-- >ID</replaceable></option></arg> -->
      <!-- <sbr/> -->
      <arg>--</arg>
      <arg>
	<replaceable>MANDOS_CLIENT</replaceable>
	<group rep="repeat">
	  <arg choice="plain"><replaceable>OPTIONS</replaceable></arg>
	</group>
      </arg>
    </cmdsynopsis>
    <cmdsynopsis>
      <command>&COMMANDNAME;</command>
      <arg choice="plain"><option>--test</option></arg>
    </cmdsynopsis>
    <cmdsynopsis>
      <command>&COMMANDNAME;</command>
      <group choice="req">
	<arg choice="plain"><option>--help</option></arg>
	<arg choice="plain"><option>-?</option></arg>
      </group>
    </cmdsynopsis>
    <cmdsynopsis>
      <command>&COMMANDNAME;</command>
      <arg choice="plain"><option>--usage</option></arg>
    </cmdsynopsis>
    <cmdsynopsis>
      <command>&COMMANDNAME;</command>
      <group choice="req">
	<arg choice="plain"><option>--version</option></arg>
	<arg choice="plain"><option>-V</option></arg>
      </group>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1 id="description">
    <title>DESCRIPTION</title>
    <para>
      <command>&COMMANDNAME;</command> is a program which is meant to
      be a <citerefentry><refentrytitle>systemd</refentrytitle>
      <manvolnum>1</manvolnum></citerefentry> <quote>Password
      Agent</quote> (See <ulink
      url="https://www.freedesktop.org/wiki/Software/systemd/PasswordAgents/"
      >Password Agents</ulink>).  The aim of this program is therefore
      to acquire and then send a password to some other program which
      will use the password to unlock the encrypted root disk.
    </para>
    <para>
      This program is not meant to be invoked directly, but can be in
      order to test it.
    </para>
  </refsect1>

  <refsect1 id="purpose">
    <title>PURPOSE</title>
    <para>
      The purpose of this is to enable <emphasis>remote and unattended
      rebooting</emphasis> of client host computer with an
      <emphasis>encrypted root file system</emphasis>.  See <xref
      linkend="overview"/> for details.
    </para>
  </refsect1>

  <refsect1>
    <title>OPTIONS</title>
    <variablelist>

      <varlistentry>
	<term><option>--agent-directory
	<replaceable>DIRECTORY</replaceable></option></term>
	<listitem>
	  <para>
	    Specify a different agent directory.  The default is
	    <quote><filename class="directory"
	    >/run/systemd/ask-password</filename ></quote> as per the
	    <ulink
	    url="https://www.freedesktop.org/wiki/Software/systemd/PasswordAgents/"
	    >Password Agents</ulink> specification.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term><option>--helper-directory
	<replaceable>DIRECTORY</replaceable></option></term>
	<listitem>
	  <para>
	    Specify a different helper directory.  The default is
	    <quote><filename class="directory"
			     >/lib/mandos/plugin-helpers</filename
			     ></quote>, which
	    will exist in the initial <acronym>RAM</acronym> disk
	    environment.  (This will simply be passed to the
	    <replaceable>MANDOS_CLIENT</replaceable> program via the
	    <envar>MANDOSPLUGINHELPERDIR</envar> environment variable.
	    See
	    <citerefentry><refentrytitle>mandos-client</refentrytitle
	    ><manvolnum>8mandos</manvolnum></citerefentry>.)
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term><option>--user
	<replaceable>USERID</replaceable></option></term>
	<listitem>
	  <para>
	    Change real user ID to <replaceable>USERID</replaceable>
	    when running <replaceable>MANDOS_CLIENT</replaceable>.
	    The default is 65534.  <emphasis>Note:</emphasis> This
	    must be a number, not a name.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term><option>--group
	<replaceable>GROUPID</replaceable></option></term>
	<listitem>
	  <para>
	    Change real group ID to <replaceable>GROUPID</replaceable>
	    when running <replaceable>MANDOS_CLIENT</replaceable>.
	    The default is 65534.  <emphasis>Note:</emphasis> This
	    must be a number, not a name.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term><replaceable>MANDOS_CLIENT</replaceable></term>
	<listitem>
	  <para>
	    This specifies the file name for
	    <citerefentry><refentrytitle>mandos-client</refentrytitle
	    ><manvolnum>8mandos</manvolnum></citerefentry>.  If the
	    <quote><option>--</option></quote> option is given, any
	    following options are passed to the <replaceable
	    >MANDOS_CLIENT</replaceable> program.  The default is
	    <quote><filename
	    >/lib/mandos/plugins.d/mandos-client</filename ></quote>
	    (which is the correct location for the initial
	    <acronym>RAM</acronym> disk environment) without any
	    options.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term><option>--help</option></term>
	<term><option>-?</option></term>
	<listitem>
	  <para>
	    Gives a help message about options and their meanings.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term><option>--test</option></term>
	<listitem>
	  <para>
	    Ignore normal operation; instead only run self-tests.
	    Adding the <option>--help</option> option may show more
	    options possible in combination with
	    <option>--test</option>.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term><option>--usage</option></term>
	<listitem>
	  <para>
	    Gives a short usage message.
	  </para>
	</listitem>
      </varlistentry>

      <varlistentry>
	<term><option>--version</option></term>
	<term><option>-V</option></term>
	<listitem>
	  <para>
	    Prints the program version.
	  </para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1 id="overview">
    <title>OVERVIEW</title>
    <xi:include href="../overview.xml"/>
    <para>
      This program, &COMMANDNAME;, will run on the client side in the
      initial <acronym>RAM</acronym> disk environment, and is
      responsible for getting a password from the Mandos client
      program itself, and to send that password to whatever is
      currently asking for a password using the systemd <ulink
      url="https://www.freedesktop.org/wiki/Software/systemd/PasswordAgents/"
      >Password Agents</ulink> mechanism.
    </para>
    <para>To accomplish this, &COMMANDNAME; runs the
    <command>mandos-client</command> program (which is the actual
    client program communicating with the Mandos server) or,
    alternatively, any executable file specified as
    <replaceable>MANDOS_CLIENT</replaceable>, and, as soon as a
    password is acquired from the
    <replaceable>MANDOS_CLIENT</replaceable> program, sends that
    password (as per the <ulink
    url="https://www.freedesktop.org/wiki/Software/systemd/PasswordAgents/"
    >Password Agents</ulink> specification) to all currently
    unanswered password questions.
    </para>
    <para>
      This program should be started (normally as a systemd service,
      which in turn is normally started by a <citerefentry
      ><refentrytitle>systemd.path</refentrytitle>
      <manvolnum>5</manvolnum></citerefentry> file) as a reaction to
      files named <quote><filename>ask.<replaceable>xxxx</replaceable
      ></filename></quote> appearing in the agent directory
      <quote><filename
      class="directory">/run/systemd/ask-password</filename></quote>
      (or the directory specified by
      <option>--agent-directory</option>).
    </para>
  </refsect1>

  <refsect1 id="exit_status">
    <title>EXIT STATUS</title>
    <para>
      Exit status of this program is zero if no errors were
      encountered, and otherwise not.
    </para>
  </refsect1>

  <refsect1 id="environment">
    <title>ENVIRONMENT</title>
    <para>
      This program does not use any environment variables itself, it
      only passes on its environment to
      <replaceable>MANDOS_CLIENT</replaceable>.  Also, the
      <option>--helper-directory</option> option will affect the
      environment variable <envar>MANDOSPLUGINHELPERDIR</envar> for
      <replaceable>MANDOS_CLIENT</replaceable>.
    </para>
  </refsect1>

  <refsect1 id="files">
    <title>FILES</title>
    <para>
      <variablelist>
	<varlistentry>
	  <term><filename class="directory"
			  >/run/systemd/ask-password</filename></term>
	  <listitem>
	    <para>
	      The default directory to watch for password questions as
	      per the <ulink
	      url="https://www.freedesktop.org/wiki/Software/systemd/PasswordAgents/"
	      >Password Agents</ulink> specification; can be changed
	      by the <option>--agent-directory</option> option.
	    </para>
	  </listitem>
	</varlistentry>
	<varlistentry>
	  <term><filename class="directory"
			  >/lib/mandos/plugin-helpers</filename
			  ></term>
	  <listitem>
	    <para>
	      The helper directory as supplied to
	      <replaceable>MANDOS_CLIENT</replaceable> via the
	      <envar>MANDOSPLUGINHELPERDIR</envar> environment
	      variable; can be changed by the
	      <option>--helper-directory</option> option.
	    </para>
	  </listitem>
	</varlistentry>
      </variablelist>
    </para>
  </refsect1>

  <refsect1 id="bugs">
    <title>BUGS</title>
    <xi:include href="../bugs.xml"/>
  </refsect1>

  <refsect1 id="examples">
    <title>EXAMPLE</title>
    <informalexample>
      <para>
	Normal invocation needs no options:
      </para>
      <para>
	<userinput>&COMMANDNAME;</userinput>
      </para>
    </informalexample>
    <informalexample>
      <para>
	Run an alternative <replaceable>MANDOS_CLIENT</replaceable>
	program::
      </para>
      <para>
	<userinput>&COMMANDNAME; /usr/local/sbin/alternate</userinput>
      </para>
    </informalexample>
    <informalexample>
      <para>
	Use alternative locations for the helper directory and the
	Mandos client, and add extra options suitable for running in
	the normal file system:
      </para>
      <para>
	
	<!-- do not wrap this line -->
	<userinput>&COMMANDNAME; --helper-directory=/usr/lib/x86_64-linux-gnu/mandos/plugin-helpers -- /usr/lib/x86_64-linux-gnu/mandos/plugins.d/mandos-client --pubkey=/etc/keys/mandos/pubkey.txt --seckey=/etc/keys/mandos/seckey.txt --tls-pubkey=/etc/keys/mandos/tls-pubkey.pem --tls-privkey=/etc/keys/mandos/tls-privkey.pem</userinput>
	
      </para>
    </informalexample>
    <informalexample>
      <para>
	Use the default location for
	<citerefentry><refentrytitle>mandos-client</refentrytitle>
	<manvolnum>8mandos</manvolnum></citerefentry>, but add many
	options to it:
      </para>
      <para>

<!-- do not wrap this line -->
<userinput>&COMMANDNAME; -- /lib/mandos/mandos-client --pubkey=/etc/mandos/keys/pubkey.txt --seckey=/etc/mandos/keys/seckey.txt --tls-pubkey=/etc/mandos/keys/tls-pubkey.pem --tls-privkey=/etc/mandos/keys/tls-privkey.pem</userinput>

      </para>
    </informalexample>
    <informalexample>
      <para>
	Only run the self-tests:
      </para>
      <para>
	<userinput>&COMMANDNAME; --test</userinput>
      </para>
    </informalexample>
  </refsect1>
  <refsect1 id="security">
    <title>SECURITY</title>
    <para>
      This program will need to run as the root user in order to read
      the agent directory and the <quote><filename
      >ask.<replaceable>xxxx</replaceable></filename></quote> files
      there, and will, when starting the Mandos client program,
      require the ability to set the <quote>real</quote> user and
      group ids to another user, by default user and group 65534,
      which are assumed to be non-privileged.  This is done in order
      to match the expectations of <citerefentry><refentrytitle
      >mandos-client</refentrytitle><manvolnum>8mandos</manvolnum
      ></citerefentry>, which assumes that its executable file is
      owned by the root user and also has the set-user-ID bit set (see
      <citerefentry><refentrytitle>execve</refentrytitle><manvolnum
      >2</manvolnum></citerefentry>).
    </para>
  </refsect1>

  <refsect1 id="see_also">
    <title>SEE ALSO</title>
    <para>
      <citerefentry><refentrytitle>intro</refentrytitle>
      <manvolnum>8mandos</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>mandos-client</refentrytitle>
      <manvolnum>8mandos</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd</refentrytitle>
      <manvolnum>1</manvolnum></citerefentry>,
    </para>
    <variablelist>
      <varlistentry>
	<term>
	  <ulink
	      url="https://www.freedesktop.org/wiki/Software/systemd/PasswordAgents/"
	      >Password Agents</ulink>
	</term>
	<listitem>
	  <para>
	    The specification for systemd <quote>Password
	    Agent</quote> programs, which
	    <command>&COMMANDNAME;</command> follows.
	  </para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

</refentry>
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