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<filename>/lib/mandos/plugins.d</filename>, but this can be
426
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changed with the <option>--plugin-dir</option> option. The
427
328
plugins are started in parallel, and the first plugin to output
428
a password <emphasis>and</emphasis> exit with a successful exit
429
code will make this plugin-runner output the password from that
430
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
433
<refsect2 id="writing_plugins">
434
<title>WRITING PLUGINS</title>
436
A plugin is simply a program which prints a password to its
437
standard output and then exits with a successful (zero) exit
438
status. If the exit status is not zero, any output on
439
standard output will be ignored by the plugin runner. Any
440
output on its standard error channel will simply be passed to
441
the standard error of the plugin runner, usually the system
445
If the password is a single-line, manually entered passprase,
446
a final trailing newline character should
447
<emphasis>not</emphasis> be printed.
450
The plugin will run in the initial RAM disk environment, so
451
care must be taken not to depend on any files or running
452
services not available there. Any helper executables required
453
by the plugin (which are not in the <envar>PATH</envar>) can
454
be placed in the plugin helper directory, the name of which
455
will be made available to the plugin via the
456
<envar>MANDOSPLUGINHELPERDIR</envar> environment variable.
459
The plugin must exit cleanly and free all allocated resources
460
upon getting the TERM signal, since this is what the plugin
461
runner uses to stop all other plugins when one plugin has
462
output a password and exited cleanly.
465
The plugin must not use resources, like for instance reading
466
from the standard input, without knowing that no other plugin
470
It is useful, but not required, for the plugin to take the
471
<option>--debug</option> option.
476
<refsect1 id="fallback">
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336
<title>FALLBACK</title>
479
If no plugins succeed, this program will, as a fallback, ask for
480
a password on the console using <citerefentry><refentrytitle
481
>getpass</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
482
and output it. This is not meant to be the normal mode of
483
operation, as there is a separate plugin for getting a password
488
340
<refsect1 id="exit_status">
489
341
<title>EXIT STATUS</title>
491
Exit status of this program is zero if no errors were
492
encountered, and otherwise not. The fallback (see <xref
493
linkend="fallback"/>) may or may not have succeeded in either
498
<refsect1 id="environment">
499
<title>ENVIRONMENT</title>
501
This program does not use any environment variables itself, it
502
only passes on its environment to all the plugins. The
503
environment passed to plugins can be modified using the
504
<option>--global-env</option> and <option>--env-for</option>
505
options. Also, the <option>--plugin-helper-dir</option> option
506
will affect the environment variable
507
<envar>MANDOSPLUGINHELPERDIR</envar> for the plugins.
511
<refsect1 id="files">
512
347
<title>FILES</title>
517
>/conf/conf.d/mandos/plugin-runner.conf</filename></term>
520
Since this program will be run as a keyscript, there is
521
little to no opportunity to pass command line arguments
522
to it. Therefore, it will <emphasis>also</emphasis>
523
read this file and use its contents as
524
whitespace-separated command line options. Also,
525
everything from a <quote>#</quote> character to the end
526
of a line is ignored.
529
This program is meant to run in the initial RAM disk
530
environment, so that is where this file is assumed to
531
exist. The file does not need to exist in the normal
535
This file will be processed <emphasis>before</emphasis>
536
the normal command line options, so the latter can
537
override the former, if need be.
540
This file name is the default; the file to read for
541
arguments can be changed using the
542
<option>--config-file</option> option.
352
<refsect1 id="notes">
550
358
<refsect1 id="bugs">
551
359
<title>BUGS</title>
553
The <option>--config-file</option> option is ignored when
554
specified from within a configuration file.
558
364
<refsect1 id="examples">
559
365
<title>EXAMPLE</title>
562
Normal invocation needs no options:
565
<userinput>&COMMANDNAME;</userinput>
570
Run the program, but not the plugins, in debug mode:
574
<!-- do not wrap this line -->
575
<userinput>&COMMANDNAME; --debug</userinput>
581
Run all plugins, but run the <quote>foo</quote> plugin in
586
<!-- do not wrap this line -->
587
<userinput>&COMMANDNAME; --options-for=foo:--debug</userinput>
593
Run all plugins, but not the program, in debug mode:
597
<!-- do not wrap this line -->
598
<userinput>&COMMANDNAME; --global-options=--debug</userinput>
604
Read a different configuration file, run plugins from a
605
different directory, specify an alternate plugin helper
606
directory and add two options to the
607
<citerefentry><refentrytitle >mandos-client</refentrytitle>
608
<manvolnum>8mandos</manvolnum></citerefentry> plugin:
612
<!-- do not wrap this line -->
613
<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>
618
370
<refsect1 id="security">
619
371
<title>SECURITY</title>
621
This program will, when starting, try to switch to another user.
622
If it is started as root, it will succeed, and will by default
623
switch to user and group 65534, which are assumed to be
624
non-privileged. This user and group is then what all plugins
625
will be started as. Therefore, the only way to run a plugin as
626
a privileged user is to have the set-user-ID or set-group-ID bit
627
set on the plugin executable file (see <citerefentry>
628
<refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum>
632
If this program is used as a keyscript in <citerefentry
633
><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
634
</citerefentry>, there is a slight risk that if this program
635
fails to work, there might be no way to boot the system except
636
for booting from another media and editing the initial RAM disk
637
image to not run this program. This is, however, unlikely,
638
since the <citerefentry><refentrytitle
639
>password-prompt</refentrytitle><manvolnum>8mandos</manvolnum>
640
</citerefentry> plugin will read a password from the console in
641
case of failure of the other plugins, and this plugin runner
642
will also, in case of catastrophic failure, itself fall back to
643
asking and outputting a password on the console (see <xref
644
linkend="fallback"/>).
648
376
<refsect1 id="see_also">
649
377
<title>SEE ALSO</title>
651
<citerefentry><refentrytitle>intro</refentrytitle>
652
<manvolnum>8mandos</manvolnum></citerefentry>,
653
379
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
654
380
<manvolnum>8</manvolnum></citerefentry>,
655
<citerefentry><refentrytitle>crypttab</refentrytitle>
656
<manvolnum>5</manvolnum></citerefentry>,
657
<citerefentry><refentrytitle>execve</refentrytitle>
658
<manvolnum>2</manvolnum></citerefentry>,
659
381
<citerefentry><refentrytitle>mandos</refentrytitle>
660
382
<manvolnum>8</manvolnum></citerefentry>,
661
383
<citerefentry><refentrytitle>password-prompt</refentrytitle>
662
384
<manvolnum>8mandos</manvolnum></citerefentry>,
663
<citerefentry><refentrytitle>mandos-client</refentrytitle>
385
<citerefentry><refentrytitle>password-request</refentrytitle>
664
386
<manvolnum>8mandos</manvolnum></citerefentry>
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