399
326
<filename>/lib/mandos/plugins.d</filename>, but this can be
400
327
changed with the <option>--plugin-dir</option> option. The
401
328
plugins are started in parallel, and the first plugin to output
402
a password <emphasis>and</emphasis> exit with a successful exit
403
code will make this plugin-runner output the password from that
404
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
407
<refsect2 id="writing_plugins">
408
<title>WRITING PLUGINS</title>
410
A plugin is simply a program which prints a password to its
411
standard output and then exits with a successful (zero) exit
412
status. If the exit status is not zero, any output on
413
standard output will be ignored by the plugin runner. Any
414
output on its standard error channel will simply be passed to
415
the standard error of the plugin runner, usually the system
419
The plugin will run in the initial RAM disk environment, so
420
care must be taken not to depend on any files or running
421
services not available there.
424
The plugin must exit cleanly and free all allocated resources
425
upon getting the TERM signal, since this is what the plugin
426
runner uses to stop all other plugins when one plugin has
427
output a password and exited cleanly.
430
The plugin must not use resources, like for instance reading
431
from the standard input, without knowing that no other plugin
435
It is useful, but not required, for the plugin to take the
436
<option>--debug</option> option.
441
<refsect1 id="fallback">
442
336
<title>FALLBACK</title>
444
If no plugins succeed, this program will, as a fallback, ask for
445
a password on the console using <citerefentry><refentrytitle
446
>getpass</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
447
and output it. This is not meant to be the normal mode of
448
operation, as there is a separate plugin for getting a password
453
340
<refsect1 id="exit_status">
454
341
<title>EXIT STATUS</title>
456
Exit status of this program is zero if no errors were
457
encountered, and otherwise not. The fallback (see <xref
458
linkend="fallback"/>) may or may not have succeeded in either
463
<refsect1 id="environment">
464
<title>ENVIRONMENT</title>
466
This program does not use any environment variables itself, it
467
only passes on its environment to all the plugins. The
468
environment passed to plugins can be modified using the
469
<option>--global-env</option> and <option>--env-for</option>
474
<refsect1 id="files">
475
347
<title>FILES</title>
480
>/conf/conf.d/mandos/plugin-runner.conf</filename></term>
483
Since this program will be run as a keyscript, there is
484
little to no opportunity to pass command line arguments
485
to it. Therefore, it will <emphasis>also</emphasis>
486
read this file and use its contents as
487
whitespace-separated command line options. Also,
488
everything from a <quote>#</quote> character to the end
489
of a line is ignored.
492
This program is meant to run in the initial RAM disk
493
environment, so that is where this file is assumed to
494
exist. The file does not need to exist in the normal
498
This file will be processed <emphasis>before</emphasis>
499
the normal command line options, so the latter can
500
override the former, if need be.
503
This file name is the default; the file to read for
504
arguments can be changed using the
505
<option>--config-file</option> option.
352
<refsect1 id="notes">
513
358
<refsect1 id="bugs">
514
359
<title>BUGS</title>
516
The <option>--config-file</option> option is ignored when
517
specified from within a configuration file.
521
364
<refsect1 id="examples">
522
365
<title>EXAMPLE</title>
525
Normal invocation needs no options:
528
<userinput>&COMMANDNAME;</userinput>
533
Run the program, but not the plugins, in debug mode:
537
<!-- do not wrap this line -->
538
<userinput>&COMMANDNAME; --debug</userinput>
544
Run all plugins, but run the <quote>foo</quote> plugin in
549
<!-- do not wrap this line -->
550
<userinput>&COMMANDNAME; --options-for=foo:--debug</userinput>
556
Run all plugins, but not the program, in debug mode:
560
<!-- do not wrap this line -->
561
<userinput>&COMMANDNAME; --global-options=--debug</userinput>
567
Run plugins from a different directory and add two
568
options to the <citerefentry><refentrytitle
569
>password-request</refentrytitle>
570
<manvolnum>8mandos</manvolnum></citerefentry> plugin:
574
<!-- do not wrap this line -->
575
<userinput>&COMMANDNAME; --plugin-dir=plugins.d --options-for=password-request:--pubkey=keydir/pubkey.txt,--seckey=keydir/seckey.txt</userinput>
580
370
<refsect1 id="security">
581
371
<title>SECURITY</title>
583
This program will, when starting, try to switch to another user.
584
If it is started as root, it will succeed, and will by default
585
switch to user and group 65534, which are assumed to be
586
non-privileged. This user and group is then what all plugins
587
will be started as. Therefore, the only way to run a plugin as
588
a privileged user is to have the set-user-ID or set-group-ID bit
589
set on the plugin executable files (see <citerefentry>
590
<refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum>
594
If this program is used as a keyscript in <citerefentry
595
><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
596
</citerefentry>, there is a slight risk that if this program
597
fails to work, there might be no way to boot the system except
598
for booting from another media and editing the initial RAM disk
599
image to not run this program. This is, however, unlikely,
600
since the <citerefentry><refentrytitle
601
>password-prompt</refentrytitle><manvolnum>8mandos</manvolnum>
602
</citerefentry> plugin will read a password from the console in
603
case of failure of the other plugins, and this plugin runner
604
will also, in case of catastrophic failure, itself fall back to
605
asking and outputting a password on the console (see <xref
606
linkend="fallback"/>).
610
376
<refsect1 id="see_also">
611
377
<title>SEE ALSO</title>
613
379
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
614
380
<manvolnum>8</manvolnum></citerefentry>,
615
<citerefentry><refentrytitle>crypttab</refentrytitle>
616
<manvolnum>5</manvolnum></citerefentry>,
617
<citerefentry><refentrytitle>execve</refentrytitle>
618
<manvolnum>2</manvolnum></citerefentry>,
619
381
<citerefentry><refentrytitle>mandos</refentrytitle>
620
382
<manvolnum>8</manvolnum></citerefentry>,
621
383
<citerefentry><refentrytitle>password-prompt</refentrytitle>