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<filename>/lib/mandos/plugins.d</filename>, but this can be
402
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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
404
a password <emphasis>and</emphasis> exit with a successful exit
405
code will make this plugin-runner output the password from that
406
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>
412
A plugin is simply a program which prints a password to its
413
standard output and then exits with a successful (zero) exit
414
status. If the exit status is not zero, any output on
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standard output will be ignored by the plugin runner. Any
416
output on its standard error channel will simply be passed to
417
the standard error of the plugin runner, usually the system
421
If the password is a single-line, manually entered passprase,
422
a final trailing newline character should
423
<emphasis>not</emphasis> be printed.
426
The plugin will run in the initial RAM disk environment, so
427
care must be taken not to depend on any files or running
428
services not available there.
431
The plugin must exit cleanly and free all allocated resources
432
upon getting the TERM signal, since this is what the plugin
433
runner uses to stop all other plugins when one plugin has
434
output a password and exited cleanly.
437
The plugin must not use resources, like for instance reading
438
from the standard input, without knowing that no other plugin
442
It is useful, but not required, for the plugin to take the
443
<option>--debug</option> option.
448
<refsect1 id="fallback">
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336
<title>FALLBACK</title>
451
If no plugins succeed, this program will, as a fallback, ask for
452
a password on the console using <citerefentry><refentrytitle
453
>getpass</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
454
and output it. This is not meant to be the normal mode of
455
operation, as there is a separate plugin for getting a password
460
340
<refsect1 id="exit_status">
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<title>EXIT STATUS</title>
463
Exit status of this program is zero if no errors were
464
encountered, and otherwise not. The fallback (see <xref
465
linkend="fallback"/>) may or may not have succeeded in either
470
<refsect1 id="environment">
471
<title>ENVIRONMENT</title>
473
This program does not use any environment variables itself, it
474
only passes on its environment to all the plugins. The
475
environment passed to plugins can be modified using the
476
<option>--global-env</option> and <option>--env-for</option>
481
<refsect1 id="files">
482
347
<title>FILES</title>
487
>/conf/conf.d/mandos/plugin-runner.conf</filename></term>
490
Since this program will be run as a keyscript, there is
491
little to no opportunity to pass command line arguments
492
to it. Therefore, it will <emphasis>also</emphasis>
493
read this file and use its contents as
494
whitespace-separated command line options. Also,
495
everything from a <quote>#</quote> character to the end
496
of a line is ignored.
499
This program is meant to run in the initial RAM disk
500
environment, so that is where this file is assumed to
501
exist. The file does not need to exist in the normal
505
This file will be processed <emphasis>before</emphasis>
506
the normal command line options, so the latter can
507
override the former, if need be.
510
This file name is the default; the file to read for
511
arguments can be changed using the
512
<option>--config-file</option> option.
352
<refsect1 id="notes">
520
358
<refsect1 id="bugs">
521
359
<title>BUGS</title>
523
The <option>--config-file</option> option is ignored when
524
specified from within a configuration file.
528
364
<refsect1 id="examples">
529
365
<title>EXAMPLE</title>
532
Normal invocation needs no options:
535
<userinput>&COMMANDNAME;</userinput>
540
Run the program, but not the plugins, in debug mode:
544
<!-- do not wrap this line -->
545
<userinput>&COMMANDNAME; --debug</userinput>
551
Run all plugins, but run the <quote>foo</quote> plugin in
556
<!-- do not wrap this line -->
557
<userinput>&COMMANDNAME; --options-for=foo:--debug</userinput>
563
Run all plugins, but not the program, in debug mode:
567
<!-- do not wrap this line -->
568
<userinput>&COMMANDNAME; --global-options=--debug</userinput>
574
Run plugins from a different directory, read a different
575
configuration file, and add two options to the
576
<citerefentry><refentrytitle >mandos-client</refentrytitle>
577
<manvolnum>8mandos</manvolnum></citerefentry> plugin:
581
<!-- do not wrap this line -->
582
<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>
587
370
<refsect1 id="security">
588
371
<title>SECURITY</title>
590
This program will, when starting, try to switch to another user.
591
If it is started as root, it will succeed, and will by default
592
switch to user and group 65534, which are assumed to be
593
non-privileged. This user and group is then what all plugins
594
will be started as. Therefore, the only way to run a plugin as
595
a privileged user is to have the set-user-ID or set-group-ID bit
596
set on the plugin executable file (see <citerefentry>
597
<refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum>
601
If this program is used as a keyscript in <citerefentry
602
><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
603
</citerefentry>, there is a slight risk that if this program
604
fails to work, there might be no way to boot the system except
605
for booting from another media and editing the initial RAM disk
606
image to not run this program. This is, however, unlikely,
607
since the <citerefentry><refentrytitle
608
>password-prompt</refentrytitle><manvolnum>8mandos</manvolnum>
609
</citerefentry> plugin will read a password from the console in
610
case of failure of the other plugins, and this plugin runner
611
will also, in case of catastrophic failure, itself fall back to
612
asking and outputting a password on the console (see <xref
613
linkend="fallback"/>).
617
376
<refsect1 id="see_also">
618
377
<title>SEE ALSO</title>
620
379
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
621
380
<manvolnum>8</manvolnum></citerefentry>,
622
<citerefentry><refentrytitle>crypttab</refentrytitle>
623
<manvolnum>5</manvolnum></citerefentry>,
624
<citerefentry><refentrytitle>execve</refentrytitle>
625
<manvolnum>2</manvolnum></citerefentry>,
626
381
<citerefentry><refentrytitle>mandos</refentrytitle>
627
382
<manvolnum>8</manvolnum></citerefentry>,
628
383
<citerefentry><refentrytitle>password-prompt</refentrytitle>
629
384
<manvolnum>8mandos</manvolnum></citerefentry>,
630
<citerefentry><refentrytitle>mandos-client</refentrytitle>
385
<citerefentry><refentrytitle>password-request</refentrytitle>
631
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<manvolnum>8mandos</manvolnum></citerefentry>
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