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Viewing changes to mandos-clients.conf.xml

  • Committer: Teddy Hogeborn
  • Date: 2015-05-23 20:18:34 UTC
  • mto: (237.7.304 trunk)
  • mto: This revision was merged to the branch mainline in revision 325.
  • Revision ID: teddy@recompile.se-20150523201834-e89ex4ito93yni8x
mandos: Use multiprocessing module to run checkers.

For a long time, the Mandos server has occasionally logged the message
"ERROR: Child process vanished".  This was never a fatal error, but it
has been annoying and slightly worrying, since a definite cause was
not found.  One potential cause could be the "multiprocessing" and
"subprocess" modules conflicting w.r.t. SIGCHLD.  To avoid this,
change the running of checkers from using subprocess.Popen
asynchronously to instead first create a multiprocessing.Process()
(which is asynchronous) calling a function, and have that function
then call subprocess.call() (which is synchronous).  In this way, the
only thing using any asynchronous subprocesses is the multiprocessing
module.

This makes it necessary to change one small thing in the D-Bus API,
since the subprocesses.call() function does not expose the raw wait(2)
status value.

DBUS-API (CheckerCompleted): Change the second value provided by this
                             D-Bus signal from the raw wait(2) status
                             to the actual terminating signal number.
mandos (subprocess_call_pipe): New function to be called by
                               multiprocessing.Process (starting a
                               separate process).
(Client.last_checker signal): New attribute for signal which
                              terminated last checker.  Like
                              last_checker_status, only not accessible
                              via D-Bus.
(Client.checker_callback): Take new "connection" argument and use it
                           to get returncode; set last_checker_signal.
                           Return False so gobject does not call this
                           callback again.
(Client.start_checker): Start checker using a multiprocessing.Process
                        instead of a subprocess.Popen.
(ClientDBus.checker_callback): Take new "connection" argument.        Call
                               Client.checker_callback early to have
                               it set last_checker_status and
                               last_checker_signal; use those.  Change
                               second value provided to D-Bus signal
                               CheckerCompleted to use
                               last_checker_signal if checker was
                               terminated by signal.
mandos-monitor: Update to reflect DBus API change.
(MandosClientWidget.checker_completed): Take "signal" instead of
                                        "condition" argument.  Use it
                                        accordingly.  Remove dead code
                                        (os.WCOREDUMP case).

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        "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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<!ENTITY CONFNAME "mandos-clients.conf">
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<!ENTITY CONFPATH "<filename>/etc/mandos/clients.conf</filename>">
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<!ENTITY TIMESTAMP "2011-10-10">
 
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<!ENTITY TIMESTAMP "2014-06-22">
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<!ENTITY % common SYSTEM "common.ent">
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%common;
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]>
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      <year>2009</year>
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      <year>2010</year>
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      <year>2011</year>
 
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      <year>2012</year>
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      <holder>Teddy Hogeborn</holder>
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      <holder>Björn Påhlsson</holder>
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    </copyright>
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      ><refentrytitle>mandos</refentrytitle>
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      <manvolnum>8</manvolnum></citerefentry>, read by it at startup.
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      The file needs to list all clients that should be able to use
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      the service.  All clients listed will be regarded as enabled,
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      even if a client was disabled in a previous run of the server.
 
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      the service.  The settings in this file can be overridden by
 
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      runtime changes to the server, which it saves across restarts.
 
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      (See the section called <quote>PERSISTENT STATE</quote> in
 
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      <citerefentry><refentrytitle>mandos</refentrytitle><manvolnum
 
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      >8</manvolnum></citerefentry>.)  However, any <emphasis
 
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      >changes</emphasis> to this file (including adding and removing
 
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      clients) will, at startup, override changes done during runtime.
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    </para>
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    <para>
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      The format starts with a <literal>[<replaceable>section
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          <para>
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            How long to wait for external approval before resorting to
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            use the <option>approved_by_default</option> value.  The
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            default is <quote>0s</quote>, i.e. not to wait.
 
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            default is <quote>PT0S</quote>, i.e. not to wait.
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          </para>
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          <para>
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            The format of <replaceable>TIME</replaceable> is the same
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            This option is <emphasis>optional</emphasis>.
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          </para>
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          <para>
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            This option allows you to override the default shell
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            command that the server will use to check if the client is
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            still up.  Any output of the command will be ignored, only
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            the exit code is checked:  If the exit code of the command
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            is zero, the client is considered up.  The command will be
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            run using <quote><command><filename>/bin/sh</filename>
 
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            This option overrides the default shell command that the
 
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            server will use to check if the client is still up.  Any
 
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            output of the command will be ignored, only the exit code
 
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            is checked:  If the exit code of the command is zero, the
 
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            client is considered up.  The command will be run using
 
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            <quote><command><filename>/bin/sh</filename>
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            <option>-c</option></command></quote>, so
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            <varname>PATH</varname> will be searched.  The default
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            value for the checker command is <quote><literal
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            ><command>fping</command> <option>-q</option> <option
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            >--</option> %%(host)s</literal></quote>.
 
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            >--</option> %%(host)s</literal></quote>.  Note that
 
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            <command>mandos-keygen</command>, when generating output
 
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            to be inserted into this file, normally looks for an SSH
 
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            server on the Mandos client, and, if it find one, outputs
 
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            a <option>checker</option> option to check for the
 
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            client’s key fingerprint – this is more secure against
 
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            spoofing.
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          </para>
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          <para>
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            In addition to normal start time expansion, this option
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            <option>extended_timeout</option> option.
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          </para>
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          <para>
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            The <replaceable>TIME</replaceable> is specified as a
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            space-separated number of values, each of which is a
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            number and a one-character suffix.  The suffix must be one
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            of <quote>d</quote>, <quote>s</quote>, <quote>m</quote>,
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            <quote>h</quote>, and <quote>w</quote> for days, seconds,
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            minutes, hours, and weeks, respectively.  The values are
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            added together to give the total time value, so all of
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            <quote><literal>330s</literal></quote>,
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            <quote><literal>110s 110s 110s</literal></quote>, and
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            <quote><literal>5m 30s</literal></quote> will give a value
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            of five minutes and thirty seconds.
 
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            The <replaceable>TIME</replaceable> is specified as an RFC
 
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            3339 duration; for example
 
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            <quote><literal>P1Y2M3DT4H5M6S</literal></quote> meaning
 
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            one year, two months, three days, four hours, five
 
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            minutes, and six seconds.  Some values can be omitted, see
 
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            RFC 3339 Appendix A for details.
 
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          </para>
 
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        </listitem>
 
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      </varlistentry>
 
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      <varlistentry>
 
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        <term><option>enabled<literal> = </literal>{ <literal
 
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        >1</literal> | <literal>yes</literal> | <literal>true</literal
 
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        > | <literal >on</literal> | <literal>0</literal> | <literal
 
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        >no</literal> | <literal>false</literal> | <literal
 
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        >off</literal> }</option></term>
 
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        <listitem>
 
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          <para>
 
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            Whether this client should be enabled by default.  The
 
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            default is <quote>true</quote>.
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          </para>
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        </listitem>
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      </varlistentry>
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        <quote><literal>approval_duration</literal></quote>,
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        <quote><literal>created</literal></quote>,
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        <quote><literal>enabled</literal></quote>,
 
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        <quote><literal>expires</literal></quote>,
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        <quote><literal>fingerprint</literal></quote>,
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        <quote><literal>host</literal></quote>,
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        <quote><literal>interval</literal></quote>,
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    <informalexample>
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      <programlisting>
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[DEFAULT]
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timeout = 5m
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interval = 2m
 
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timeout = PT5M
 
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interval = PT2M
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checker = fping -q -- %%(host)s
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# Client "foo"
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        4T2zw4dxS5NswXWU0sVEXxjs6PYxuIiCTL7vdpx8QjBkrPWDrAbcMyBr2O
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        QlnHIvPzEArRQLo=
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host = foo.example.org
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interval = 1m
 
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interval = PT1M
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# Client "bar"
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[bar]
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fingerprint = 3e393aeaefb84c7e89e2f547b3a107558fca3a27
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secfile = /etc/mandos/bar-secret
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timeout = 15m
 
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timeout = PT15M
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approved_by_default = False
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approval_delay = 30s
 
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approval_delay = PT30S
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      </programlisting>
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    </informalexample>
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  </refsect1>
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      <citerefentry><refentrytitle>mandos.conf</refentrytitle>
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      <manvolnum>5</manvolnum></citerefentry>,
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      <citerefentry><refentrytitle>mandos</refentrytitle>
 
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      <manvolnum>8</manvolnum></citerefentry>,
 
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      <citerefentry><refentrytitle>fping</refentrytitle>
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      <manvolnum>8</manvolnum></citerefentry>
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    </para>
 
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    <variablelist>
 
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      <varlistentry>
 
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        <term>
 
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          RFC 3339: <citetitle>Date and Time on the Internet:
 
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          Timestamps</citetitle>
 
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        </term>
 
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      <listitem>
 
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        <para>
 
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          The time intervals are in the "duration" format, as
 
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          specified in ABNF in Appendix A of RFC 3339.
 
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        </para>
 
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      </listitem>
 
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      </varlistentry>
 
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    </variablelist>
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  </refsect1>
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</refentry>
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