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<filename>/lib/mandos/plugins.d</filename>, but this can be
428
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changed with the <option>--plugin-dir</option> option. The
429
328
plugins are started in parallel, and the first plugin to output
430
a password <emphasis>and</emphasis> exit with a successful exit
431
code will make this plugin-runner output the password from that
432
plugin, stop any other plugins, and exit.
329
a password and exit with a successful exit code will make this
330
plugin-runner output that password, stop any other plugins, and
435
<refsect2 id="writing_plugins">
436
<title>WRITING PLUGINS</title>
438
A plugin is simply a program which prints a password to its
439
standard output and then exits with a successful (zero) exit
440
status. If the exit status is not zero, any output on
441
standard output will be ignored by the plugin runner. Any
442
output on its standard error channel will simply be passed to
443
the standard error of the plugin runner, usually the system
447
If the password is a single-line, manually entered passprase,
448
a final trailing newline character should
449
<emphasis>not</emphasis> be printed.
452
The plugin will run in the initial RAM disk environment, so
453
care must be taken not to depend on any files or running
454
services not available there. Any helper executables required
455
by the plugin (which are not in the <envar>PATH</envar>) can
456
be placed in the plugin helper directory, the name of which
457
will be made available to the plugin via the
458
<envar>MANDOSPLUGINHELPERDIR</envar> environment variable.
461
The plugin must exit cleanly and free all allocated resources
462
upon getting the TERM signal, since this is what the plugin
463
runner uses to stop all other plugins when one plugin has
464
output a password and exited cleanly.
467
The plugin must not use resources, like for instance reading
468
from the standard input, without knowing that no other plugin
472
It is useful, but not required, for the plugin to take the
473
<option>--debug</option> option.
478
<refsect1 id="fallback">
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336
<title>FALLBACK</title>
481
If no plugins succeed, this program will, as a fallback, ask for
482
a password on the console using <citerefentry><refentrytitle
483
>getpass</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
484
and output it. This is not meant to be the normal mode of
485
operation, as there is a separate plugin for getting a password
490
340
<refsect1 id="exit_status">
491
341
<title>EXIT STATUS</title>
493
Exit status of this program is zero if no errors were
494
encountered, and otherwise not. The fallback (see <xref
495
linkend="fallback"/>) may or may not have succeeded in either
500
<refsect1 id="environment">
501
<title>ENVIRONMENT</title>
503
This program does not use any environment variables itself, it
504
only passes on its environment to all the plugins. The
505
environment passed to plugins can be modified using the
506
<option>--global-env</option> and <option>--env-for</option>
507
options. Also, the <option>--plugin-helper-dir</option> option
508
will affect the environment variable
509
<envar>MANDOSPLUGINHELPERDIR</envar> for the plugins.
513
<refsect1 id="files">
514
347
<title>FILES</title>
519
>/conf/conf.d/mandos/plugin-runner.conf</filename></term>
522
Since this program will be run as a keyscript, there is
523
little to no opportunity to pass command line arguments
524
to it. Therefore, it will <emphasis>also</emphasis>
525
read this file and use its contents as
526
whitespace-separated command line options. Also,
527
everything from a <quote>#</quote> character to the end
528
of a line is ignored.
531
This program is meant to run in the initial RAM disk
532
environment, so that is where this file is assumed to
533
exist. The file does not need to exist in the normal
537
This file will be processed <emphasis>before</emphasis>
538
the normal command line options, so the latter can
539
override the former, if need be.
542
This file name is the default; the file to read for
543
arguments can be changed using the
544
<option>--config-file</option> option.
549
<term><filename class="directory"
550
>/lib/mandos/plugins.d</filename></term>
553
The default plugin directory; can be changed by the
554
<option>--plugin-dir</option> option.
559
<term><filename class="directory"
560
>/lib/mandos/plugin-helpers</filename></term>
563
The default plugin helper directory; can be changed by
564
the <option>--plugin-helper-dir</option> option.
352
<refsect1 id="notes">
572
358
<refsect1 id="bugs">
573
359
<title>BUGS</title>
575
The <option>--config-file</option> option is ignored when
576
specified from within a configuration file.
578
<xi:include href="bugs.xml"/>
581
364
<refsect1 id="examples">
582
365
<title>EXAMPLE</title>
585
Normal invocation needs no options:
588
<userinput>&COMMANDNAME;</userinput>
593
Run the program, but not the plugins, in debug mode:
597
<!-- do not wrap this line -->
598
<userinput>&COMMANDNAME; --debug</userinput>
604
Run all plugins, but run the <quote>foo</quote> plugin in
609
<!-- do not wrap this line -->
610
<userinput>&COMMANDNAME; --options-for=foo:--debug</userinput>
616
Run all plugins, but not the program, in debug mode:
620
<!-- do not wrap this line -->
621
<userinput>&COMMANDNAME; --global-options=--debug</userinput>
627
Read a different configuration file, run plugins from a
628
different directory, specify an alternate plugin helper
629
directory and add two options to the
630
<citerefentry><refentrytitle >mandos-client</refentrytitle>
631
<manvolnum>8mandos</manvolnum></citerefentry> plugin:
635
<!-- do not wrap this line -->
636
<userinput>cd /etc/keys/mandos; &COMMANDNAME; --config-file=/etc/mandos/plugin-runner.conf --plugin-dir /usr/lib/x86_64-linux-gnu/mandos/plugins.d --plugin-helper-dir /usr/lib/x86_64-linux-gnu/mandos/plugin-helpers --options-for=mandos-client:--pubkey=pubkey.txt,--seckey=seckey.txt</userinput>
641
370
<refsect1 id="security">
642
371
<title>SECURITY</title>
644
This program will, when starting, try to switch to another user.
645
If it is started as root, it will succeed, and will by default
646
switch to user and group 65534, which are assumed to be
647
non-privileged. This user and group is then what all plugins
648
will be started as. Therefore, the only way to run a plugin as
649
a privileged user is to have the set-user-ID or set-group-ID bit
650
set on the plugin executable file (see <citerefentry>
651
<refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum>
655
If this program is used as a keyscript in <citerefentry
656
><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
657
</citerefentry>, there is a slight risk that if this program
658
fails to work, there might be no way to boot the system except
659
for booting from another media and editing the initial RAM disk
660
image to not run this program. This is, however, unlikely,
661
since the <citerefentry><refentrytitle
662
>password-prompt</refentrytitle><manvolnum>8mandos</manvolnum>
663
</citerefentry> plugin will read a password from the console in
664
case of failure of the other plugins, and this plugin runner
665
will also, in case of catastrophic failure, itself fall back to
666
asking and outputting a password on the console (see <xref
667
linkend="fallback"/>).
671
376
<refsect1 id="see_also">
672
377
<title>SEE ALSO</title>
674
<citerefentry><refentrytitle>intro</refentrytitle>
675
<manvolnum>8mandos</manvolnum></citerefentry>,
676
379
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
677
380
<manvolnum>8</manvolnum></citerefentry>,
678
<citerefentry><refentrytitle>crypttab</refentrytitle>
679
<manvolnum>5</manvolnum></citerefentry>,
680
<citerefentry><refentrytitle>execve</refentrytitle>
681
<manvolnum>2</manvolnum></citerefentry>,
682
381
<citerefentry><refentrytitle>mandos</refentrytitle>
683
382
<manvolnum>8</manvolnum></citerefentry>,
684
383
<citerefentry><refentrytitle>password-prompt</refentrytitle>
685
384
<manvolnum>8mandos</manvolnum></citerefentry>,
686
<citerefentry><refentrytitle>mandos-client</refentrytitle>
385
<citerefentry><refentrytitle>password-request</refentrytitle>
687
386
<manvolnum>8mandos</manvolnum></citerefentry>
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