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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
428
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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
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<refsect2 id="writing_plugins">
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<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
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be placed in the plugin helper directory, the name of which
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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
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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
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<option>--debug</option> option.
477
<refsect1 id="fallback">
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<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">
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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.
352
<refsect1 id="notes">
551
358
<refsect1 id="bugs">
552
359
<title>BUGS</title>
554
The <option>--config-file</option> option is ignored when
555
specified from within a configuration file.
557
<xi:include href="bugs.xml"/>
560
364
<refsect1 id="examples">
561
365
<title>EXAMPLE</title>
564
Normal invocation needs no options:
567
<userinput>&COMMANDNAME;</userinput>
572
Run the program, but not the plugins, in debug mode:
576
<!-- do not wrap this line -->
577
<userinput>&COMMANDNAME; --debug</userinput>
583
Run all plugins, but run the <quote>foo</quote> plugin in
588
<!-- do not wrap this line -->
589
<userinput>&COMMANDNAME; --options-for=foo:--debug</userinput>
595
Run all plugins, but not the program, in debug mode:
599
<!-- do not wrap this line -->
600
<userinput>&COMMANDNAME; --global-options=--debug</userinput>
606
Read a different configuration file, run plugins from a
607
different directory, specify an alternate plugin helper
608
directory and add two options to the
609
<citerefentry><refentrytitle >mandos-client</refentrytitle>
610
<manvolnum>8mandos</manvolnum></citerefentry> plugin:
614
<!-- do not wrap this line -->
615
<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>
620
370
<refsect1 id="security">
621
371
<title>SECURITY</title>
623
This program will, when starting, try to switch to another user.
624
If it is started as root, it will succeed, and will by default
625
switch to user and group 65534, which are assumed to be
626
non-privileged. This user and group is then what all plugins
627
will be started as. Therefore, the only way to run a plugin as
628
a privileged user is to have the set-user-ID or set-group-ID bit
629
set on the plugin executable file (see <citerefentry>
630
<refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum>
634
If this program is used as a keyscript in <citerefentry
635
><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
636
</citerefentry>, there is a slight risk that if this program
637
fails to work, there might be no way to boot the system except
638
for booting from another media and editing the initial RAM disk
639
image to not run this program. This is, however, unlikely,
640
since the <citerefentry><refentrytitle
641
>password-prompt</refentrytitle><manvolnum>8mandos</manvolnum>
642
</citerefentry> plugin will read a password from the console in
643
case of failure of the other plugins, and this plugin runner
644
will also, in case of catastrophic failure, itself fall back to
645
asking and outputting a password on the console (see <xref
646
linkend="fallback"/>).
650
376
<refsect1 id="see_also">
651
377
<title>SEE ALSO</title>
653
<citerefentry><refentrytitle>intro</refentrytitle>
654
<manvolnum>8mandos</manvolnum></citerefentry>,
655
379
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
656
380
<manvolnum>8</manvolnum></citerefentry>,
657
<citerefentry><refentrytitle>crypttab</refentrytitle>
658
<manvolnum>5</manvolnum></citerefentry>,
659
<citerefentry><refentrytitle>execve</refentrytitle>
660
<manvolnum>2</manvolnum></citerefentry>,
661
381
<citerefentry><refentrytitle>mandos</refentrytitle>
662
382
<manvolnum>8</manvolnum></citerefentry>,
663
383
<citerefentry><refentrytitle>password-prompt</refentrytitle>
664
384
<manvolnum>8mandos</manvolnum></citerefentry>,
665
<citerefentry><refentrytitle>mandos-client</refentrytitle>
385
<citerefentry><refentrytitle>password-request</refentrytitle>
666
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<manvolnum>8mandos</manvolnum></citerefentry>
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