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<filename>/lib/mandos/plugins.d</filename>, but this can be
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changed with the <option>--plugin-dir</option> option. The
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plugins are started in parallel, and the first plugin to output
329
a password and exit with a successful exit code will make this
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plugin-runner output that password, stop any other plugins, and
403
a password <emphasis>and</emphasis> exit with a successful exit
404
code will make this plugin-runner output the password from that
405
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
412
standard output and then exits with a successful (zero) exit
413
status. If the exit status is not zero, any output on
414
standard output will be ignored by the plugin runner. Any
415
output on its standard error channel will simply be passed to
416
the standard error of the plugin runner, usually the system
420
If the password is a single-line, manually entered passprase,
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a final trailing newline character should
422
<emphasis>not</emphasis> be printed.
425
The plugin will run in the initial RAM disk environment, so
426
care must be taken not to depend on any files or running
427
services not available there.
430
The plugin must exit cleanly and free all allocated resources
431
upon getting the TERM signal, since this is what the plugin
432
runner uses to stop all other plugins when one plugin has
433
output a password and exited cleanly.
436
The plugin must not use resources, like for instance reading
437
from the standard input, without knowing that no other plugin
441
It is useful, but not required, for the plugin to take the
442
<option>--debug</option> option.
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<refsect1 id="fallback">
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<title>FALLBACK</title>
450
If no plugins succeed, this program will, as a fallback, ask for
451
a password on the console using <citerefentry><refentrytitle
452
>getpass</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
453
and output it. This is not meant to be the normal mode of
454
operation, as there is a separate plugin for getting a password
340
459
<refsect1 id="exit_status">
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<title>EXIT STATUS</title>
462
Exit status of this program is zero if no errors were
463
encountered, and otherwise not. The fallback (see <xref
464
linkend="fallback"/>) may or may not have succeeded in either
469
<refsect1 id="environment">
470
<title>ENVIRONMENT</title>
472
This program does not use any environment variables itself, it
473
only passes on its environment to all the plugins. The
474
environment passed to plugins can be modified using the
475
<option>--global-env</option> and <option>--env-for</option>
480
<refsect1 id="files">
347
481
<title>FILES</title>
352
<refsect1 id="notes">
486
>/conf/conf.d/mandos/plugin-runner.conf</filename></term>
489
Since this program will be run as a keyscript, there is
490
little to no opportunity to pass command line arguments
491
to it. Therefore, it will <emphasis>also</emphasis>
492
read this file and use its contents as
493
whitespace-separated command line options. Also,
494
everything from a <quote>#</quote> character to the end
495
of a line is ignored.
498
This program is meant to run in the initial RAM disk
499
environment, so that is where this file is assumed to
500
exist. The file does not need to exist in the normal
504
This file will be processed <emphasis>before</emphasis>
505
the normal command line options, so the latter can
506
override the former, if need be.
509
This file name is the default; the file to read for
510
arguments can be changed using the
511
<option>--config-file</option> option.
358
519
<refsect1 id="bugs">
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<title>BUGS</title>
522
The <option>--config-file</option> option is ignored when
523
specified from within a configuration file.
364
527
<refsect1 id="examples">
365
528
<title>EXAMPLE</title>
531
Normal invocation needs no options:
534
<userinput>&COMMANDNAME;</userinput>
539
Run the program, but not the plugins, in debug mode:
543
<!-- do not wrap this line -->
544
<userinput>&COMMANDNAME; --debug</userinput>
550
Run all plugins, but run the <quote>foo</quote> plugin in
555
<!-- do not wrap this line -->
556
<userinput>&COMMANDNAME; --options-for=foo:--debug</userinput>
562
Run all plugins, but not the program, in debug mode:
566
<!-- do not wrap this line -->
567
<userinput>&COMMANDNAME; --global-options=--debug</userinput>
573
Run plugins from a different directory, read a different
574
configuration file, and add two options to the
575
<citerefentry><refentrytitle >mandos-client</refentrytitle>
576
<manvolnum>8mandos</manvolnum></citerefentry> plugin:
580
<!-- do not wrap this line -->
581
<userinput>&COMMANDNAME; --config-file=/etc/mandos/plugin-runner.conf --plugin-dir /usr/lib/mandos/plugins.d --options-for=mandos-client:--pubkey=/etc/keys/mandos/pubkey.txt,--seckey=/etc/keys/mandos/seckey.txt</userinput>
370
586
<refsect1 id="security">
371
587
<title>SECURITY</title>
589
This program will, when starting, try to switch to another user.
590
If it is started as root, it will succeed, and will by default
591
switch to user and group 65534, which are assumed to be
592
non-privileged. This user and group is then what all plugins
593
will be started as. Therefore, the only way to run a plugin as
594
a privileged user is to have the set-user-ID or set-group-ID bit
595
set on the plugin executable file (see <citerefentry>
596
<refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum>
600
If this program is used as a keyscript in <citerefentry
601
><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
602
</citerefentry>, there is a slight risk that if this program
603
fails to work, there might be no way to boot the system except
604
for booting from another media and editing the initial RAM disk
605
image to not run this program. This is, however, unlikely,
606
since the <citerefentry><refentrytitle
607
>password-prompt</refentrytitle><manvolnum>8mandos</manvolnum>
608
</citerefentry> plugin will read a password from the console in
609
case of failure of the other plugins, and this plugin runner
610
will also, in case of catastrophic failure, itself fall back to
611
asking and outputting a password on the console (see <xref
612
linkend="fallback"/>).
376
616
<refsect1 id="see_also">
377
617
<title>SEE ALSO</title>
379
619
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
380
620
<manvolnum>8</manvolnum></citerefentry>,
621
<citerefentry><refentrytitle>crypttab</refentrytitle>
622
<manvolnum>5</manvolnum></citerefentry>,
623
<citerefentry><refentrytitle>execve</refentrytitle>
624
<manvolnum>2</manvolnum></citerefentry>,
381
625
<citerefentry><refentrytitle>mandos</refentrytitle>
382
626
<manvolnum>8</manvolnum></citerefentry>,
383
627
<citerefentry><refentrytitle>password-prompt</refentrytitle>
384
628
<manvolnum>8mandos</manvolnum></citerefentry>,
385
<citerefentry><refentrytitle>password-request</refentrytitle>
629
<citerefentry><refentrytitle>mandos-client</refentrytitle>
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630
<manvolnum>8mandos</manvolnum></citerefentry>
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