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<filename>/lib/mandos/plugins.d</filename>, but this can be
327
403
changed with the <option>--plugin-dir</option> option. The
328
404
plugins are started in parallel, and the first plugin to output
329
a password and exit with a successful exit code will make this
330
plugin-runner output that password, stop any other plugins, and
405
a password <emphasis>and</emphasis> exit with a successful exit
406
code will make this plugin-runner output the password from that
407
plugin, stop any other plugins, and exit.
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<refsect2 id="writing_plugins">
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<title>WRITING PLUGINS</title>
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A plugin is simply a program which prints a password to its
414
standard output and then exits with a successful (zero) exit
415
status. If the exit status is not zero, any output on
416
standard output will be ignored by the plugin runner. Any
417
output on its standard error channel will simply be passed to
418
the standard error of the plugin runner, usually the system
422
If the password is a single-line, manually entered passprase,
423
a final trailing newline character should
424
<emphasis>not</emphasis> be printed.
427
The plugin will run in the initial RAM disk environment, so
428
care must be taken not to depend on any files or running
429
services not available there.
432
The plugin must exit cleanly and free all allocated resources
433
upon getting the TERM signal, since this is what the plugin
434
runner uses to stop all other plugins when one plugin has
435
output a password and exited cleanly.
438
The plugin must not use resources, like for instance reading
439
from the standard input, without knowing that no other plugin
443
It is useful, but not required, for the plugin to take the
444
<option>--debug</option> option.
449
<refsect1 id="fallback">
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450
<title>FALLBACK</title>
452
If no plugins succeed, this program will, as a fallback, ask for
453
a password on the console using <citerefentry><refentrytitle
454
>getpass</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
455
and output it. This is not meant to be the normal mode of
456
operation, as there is a separate plugin for getting a password
340
461
<refsect1 id="exit_status">
341
462
<title>EXIT STATUS</title>
464
Exit status of this program is zero if no errors were
465
encountered, and otherwise not. The fallback (see <xref
466
linkend="fallback"/>) may or may not have succeeded in either
471
<refsect1 id="environment">
472
<title>ENVIRONMENT</title>
474
This program does not use any environment variables itself, it
475
only passes on its environment to all the plugins. The
476
environment passed to plugins can be modified using the
477
<option>--global-env</option> and <option>--env-for</option>
482
<refsect1 id="files">
347
483
<title>FILES</title>
352
<refsect1 id="notes">
488
>/conf/conf.d/mandos/plugin-runner.conf</filename></term>
491
Since this program will be run as a keyscript, there is
492
little to no opportunity to pass command line arguments
493
to it. Therefore, it will <emphasis>also</emphasis>
494
read this file and use its contents as
495
whitespace-separated command line options. Also,
496
everything from a <quote>#</quote> character to the end
497
of a line is ignored.
500
This program is meant to run in the initial RAM disk
501
environment, so that is where this file is assumed to
502
exist. The file does not need to exist in the normal
506
This file will be processed <emphasis>before</emphasis>
507
the normal command line options, so the latter can
508
override the former, if need be.
511
This file name is the default; the file to read for
512
arguments can be changed using the
513
<option>--config-file</option> option.
358
521
<refsect1 id="bugs">
359
522
<title>BUGS</title>
524
The <option>--config-file</option> option is ignored when
525
specified from within a configuration file.
364
529
<refsect1 id="examples">
365
530
<title>EXAMPLE</title>
533
Normal invocation needs no options:
536
<userinput>&COMMANDNAME;</userinput>
541
Run the program, but not the plugins, in debug mode:
545
<!-- do not wrap this line -->
546
<userinput>&COMMANDNAME; --debug</userinput>
552
Run all plugins, but run the <quote>foo</quote> plugin in
557
<!-- do not wrap this line -->
558
<userinput>&COMMANDNAME; --options-for=foo:--debug</userinput>
564
Run all plugins, but not the program, in debug mode:
568
<!-- do not wrap this line -->
569
<userinput>&COMMANDNAME; --global-options=--debug</userinput>
575
Run plugins from a different directory, read a different
576
configuration file, and add two options to the
577
<citerefentry><refentrytitle >mandos-client</refentrytitle>
578
<manvolnum>8mandos</manvolnum></citerefentry> plugin:
582
<!-- do not wrap this line -->
583
<userinput>cd /etc/keys/mandos; &COMMANDNAME; --config-file=/etc/mandos/plugin-runner.conf --plugin-dir /usr/lib/mandos/plugins.d --options-for=mandos-client:--pubkey=pubkey.txt,--seckey=seckey.txt</userinput>
370
588
<refsect1 id="security">
371
589
<title>SECURITY</title>
591
This program will, when starting, try to switch to another user.
592
If it is started as root, it will succeed, and will by default
593
switch to user and group 65534, which are assumed to be
594
non-privileged. This user and group is then what all plugins
595
will be started as. Therefore, the only way to run a plugin as
596
a privileged user is to have the set-user-ID or set-group-ID bit
597
set on the plugin executable file (see <citerefentry>
598
<refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum>
602
If this program is used as a keyscript in <citerefentry
603
><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
604
</citerefentry>, there is a slight risk that if this program
605
fails to work, there might be no way to boot the system except
606
for booting from another media and editing the initial RAM disk
607
image to not run this program. This is, however, unlikely,
608
since the <citerefentry><refentrytitle
609
>password-prompt</refentrytitle><manvolnum>8mandos</manvolnum>
610
</citerefentry> plugin will read a password from the console in
611
case of failure of the other plugins, and this plugin runner
612
will also, in case of catastrophic failure, itself fall back to
613
asking and outputting a password on the console (see <xref
614
linkend="fallback"/>).
376
618
<refsect1 id="see_also">
377
619
<title>SEE ALSO</title>
621
<citerefentry><refentrytitle>intro</refentrytitle>
622
<manvolnum>8mandos</manvolnum></citerefentry>,
379
623
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
380
624
<manvolnum>8</manvolnum></citerefentry>,
625
<citerefentry><refentrytitle>crypttab</refentrytitle>
626
<manvolnum>5</manvolnum></citerefentry>,
627
<citerefentry><refentrytitle>execve</refentrytitle>
628
<manvolnum>2</manvolnum></citerefentry>,
381
629
<citerefentry><refentrytitle>mandos</refentrytitle>
382
630
<manvolnum>8</manvolnum></citerefentry>,
383
631
<citerefentry><refentrytitle>password-prompt</refentrytitle>
384
632
<manvolnum>8mandos</manvolnum></citerefentry>,
385
<citerefentry><refentrytitle>password-request</refentrytitle>
633
<citerefentry><refentrytitle>mandos-client</refentrytitle>
386
634
<manvolnum>8mandos</manvolnum></citerefentry>
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