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<filename>/lib/mandos/plugins.d</filename>, but this can be
427
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changed with the <option>--plugin-dir</option> option. The
428
328
plugins are started in parallel, and the first plugin to output
429
a password <emphasis>and</emphasis> exit with a successful exit
430
code will make this plugin-runner output the password from that
431
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
434
<refsect2 id="writing_plugins">
435
<title>WRITING PLUGINS</title>
437
A plugin is simply a program which prints a password to its
438
standard output and then exits with a successful (zero) exit
439
status. If the exit status is not zero, any output on
440
standard output will be ignored by the plugin runner. Any
441
output on its standard error channel will simply be passed to
442
the standard error of the plugin runner, usually the system
446
If the password is a single-line, manually entered passprase,
447
a final trailing newline character should
448
<emphasis>not</emphasis> be printed.
451
The plugin will run in the initial RAM disk environment, so
452
care must be taken not to depend on any files or running
453
services not available there. Any helper executables required
454
by the plugin (which are not in the <envar>PATH</envar>) can
455
be placed in the plugin helper directory, the name of which
456
will be made available to the plugin via the
457
<envar>MANDOSPLUGINHELPERDIR</envar> environment variable.
460
The plugin must exit cleanly and free all allocated resources
461
upon getting the TERM signal, since this is what the plugin
462
runner uses to stop all other plugins when one plugin has
463
output a password and exited cleanly.
466
The plugin must not use resources, like for instance reading
467
from the standard input, without knowing that no other plugin
471
It is useful, but not required, for the plugin to take the
472
<option>--debug</option> option.
477
<refsect1 id="fallback">
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336
<title>FALLBACK</title>
480
If no plugins succeed, this program will, as a fallback, ask for
481
a password on the console using <citerefentry><refentrytitle
482
>getpass</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
483
and output it. This is not meant to be the normal mode of
484
operation, as there is a separate plugin for getting a password
489
340
<refsect1 id="exit_status">
490
341
<title>EXIT STATUS</title>
492
Exit status of this program is zero if no errors were
493
encountered, and otherwise not. The fallback (see <xref
494
linkend="fallback"/>) may or may not have succeeded in either
499
<refsect1 id="environment">
500
<title>ENVIRONMENT</title>
502
This program does not use any environment variables itself, it
503
only passes on its environment to all the plugins. The
504
environment passed to plugins can be modified using the
505
<option>--global-env</option> and <option>--env-for</option>
506
options. Also, the <option>--plugin-helper-dir</option> option
507
will affect the environment variable
508
<envar>MANDOSPLUGINHELPERDIR</envar> for the plugins.
512
<refsect1 id="files">
513
347
<title>FILES</title>
518
>/conf/conf.d/mandos/plugin-runner.conf</filename></term>
521
Since this program will be run as a keyscript, there is
522
little to no opportunity to pass command line arguments
523
to it. Therefore, it will <emphasis>also</emphasis>
524
read this file and use its contents as
525
whitespace-separated command line options. Also,
526
everything from a <quote>#</quote> character to the end
527
of a line is ignored.
530
This program is meant to run in the initial RAM disk
531
environment, so that is where this file is assumed to
532
exist. The file does not need to exist in the normal
536
This file will be processed <emphasis>before</emphasis>
537
the normal command line options, so the latter can
538
override the former, if need be.
541
This file name is the default; the file to read for
542
arguments can be changed using the
543
<option>--config-file</option> option.
548
<term><filename class="directory"
549
>/lib/mandos/plugins.d</filename></term>
552
The default plugin directory; can be changed by the
553
<option>--plugin-dir</option> option.
558
<term><filename class="directory"
559
>/lib/mandos/plugin-helpers</filename></term>
562
The default plugin helper directory; can be changed by
563
the <option>--plugin-helper-dir</option> option.
352
<refsect1 id="notes">
571
358
<refsect1 id="bugs">
572
359
<title>BUGS</title>
574
The <option>--config-file</option> option is ignored when
575
specified from within a configuration file.
577
<xi:include href="bugs.xml"/>
580
364
<refsect1 id="examples">
581
365
<title>EXAMPLE</title>
584
Normal invocation needs no options:
587
<userinput>&COMMANDNAME;</userinput>
592
Run the program, but not the plugins, in debug mode:
596
<!-- do not wrap this line -->
597
<userinput>&COMMANDNAME; --debug</userinput>
603
Run all plugins, but run the <quote>foo</quote> plugin in
608
<!-- do not wrap this line -->
609
<userinput>&COMMANDNAME; --options-for=foo:--debug</userinput>
615
Run all plugins, but not the program, in debug mode:
619
<!-- do not wrap this line -->
620
<userinput>&COMMANDNAME; --global-options=--debug</userinput>
626
Read a different configuration file, run plugins from a
627
different directory, specify an alternate plugin helper
628
directory and add two options to the
629
<citerefentry><refentrytitle >mandos-client</refentrytitle>
630
<manvolnum>8mandos</manvolnum></citerefentry> plugin:
634
<!-- do not wrap this line -->
635
<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>
640
370
<refsect1 id="security">
641
371
<title>SECURITY</title>
643
This program will, when starting, try to switch to another user.
644
If it is started as root, it will succeed, and will by default
645
switch to user and group 65534, which are assumed to be
646
non-privileged. This user and group is then what all plugins
647
will be started as. Therefore, the only way to run a plugin as
648
a privileged user is to have the set-user-ID or set-group-ID bit
649
set on the plugin executable file (see <citerefentry>
650
<refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum>
654
If this program is used as a keyscript in <citerefentry
655
><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
656
</citerefentry>, there is a slight risk that if this program
657
fails to work, there might be no way to boot the system except
658
for booting from another media and editing the initial RAM disk
659
image to not run this program. This is, however, unlikely,
660
since the <citerefentry><refentrytitle
661
>password-prompt</refentrytitle><manvolnum>8mandos</manvolnum>
662
</citerefentry> plugin will read a password from the console in
663
case of failure of the other plugins, and this plugin runner
664
will also, in case of catastrophic failure, itself fall back to
665
asking and outputting a password on the console (see <xref
666
linkend="fallback"/>).
670
376
<refsect1 id="see_also">
671
377
<title>SEE ALSO</title>
673
<citerefentry><refentrytitle>intro</refentrytitle>
674
<manvolnum>8mandos</manvolnum></citerefentry>,
675
379
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
676
380
<manvolnum>8</manvolnum></citerefentry>,
677
<citerefentry><refentrytitle>crypttab</refentrytitle>
678
<manvolnum>5</manvolnum></citerefentry>,
679
<citerefentry><refentrytitle>execve</refentrytitle>
680
<manvolnum>2</manvolnum></citerefentry>,
681
381
<citerefentry><refentrytitle>mandos</refentrytitle>
682
382
<manvolnum>8</manvolnum></citerefentry>,
683
383
<citerefentry><refentrytitle>password-prompt</refentrytitle>
684
384
<manvolnum>8mandos</manvolnum></citerefentry>,
685
<citerefentry><refentrytitle>mandos-client</refentrytitle>
385
<citerefentry><refentrytitle>password-request</refentrytitle>
686
386
<manvolnum>8mandos</manvolnum></citerefentry>
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