326
420
<filename>/lib/mandos/plugins.d</filename>, but this can be
327
421
changed with the <option>--plugin-dir</option> option. The
328
422
plugins are started in parallel, and the first plugin to output
329
a password and exit with a successful exit code will make this
330
plugin-runner output that password, stop any other plugins, and
423
a password <emphasis>and</emphasis> exit with a successful exit
424
code will make this plugin-runner output the password from that
425
plugin, stop any other plugins, and exit.
428
<refsect2 id="writing_plugins">
429
<title>WRITING PLUGINS</title>
431
A plugin is simply a program which prints a password to its
432
standard output and then exits with a successful (zero) exit
433
status. If the exit status is not zero, any output on
434
standard output will be ignored by the plugin runner. Any
435
output on its standard error channel will simply be passed to
436
the standard error of the plugin runner, usually the system
440
If the password is a single-line, manually entered passprase,
441
a final trailing newline character should
442
<emphasis>not</emphasis> be printed.
445
The plugin will run in the initial RAM disk environment, so
446
care must be taken not to depend on any files or running
447
services not available there. Any helper executables required
448
by the plugin (which are not in the <envar>PATH</envar>) can
449
be placed in the plugin helper directory, the name of which
450
will be made available to the plugin via the
451
<envar>MANDOSPLUGINHELPERDIR</envar> environment variable.
454
The plugin must exit cleanly and free all allocated resources
455
upon getting the TERM signal, since this is what the plugin
456
runner uses to stop all other plugins when one plugin has
457
output a password and exited cleanly.
460
The plugin must not use resources, like for instance reading
461
from the standard input, without knowing that no other plugin
465
It is useful, but not required, for the plugin to take the
466
<option>--debug</option> option.
471
<refsect1 id="fallback">
336
472
<title>FALLBACK</title>
474
If no plugins succeed, this program will, as a fallback, ask for
475
a password on the console using <citerefentry><refentrytitle
476
>getpass</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
477
and output it. This is not meant to be the normal mode of
478
operation, as there is a separate plugin for getting a password
340
483
<refsect1 id="exit_status">
341
484
<title>EXIT STATUS</title>
486
Exit status of this program is zero if no errors were
487
encountered, and otherwise not. The fallback (see <xref
488
linkend="fallback"/>) may or may not have succeeded in either
493
<refsect1 id="environment">
494
<title>ENVIRONMENT</title>
496
This program does not use any environment variables itself, it
497
only passes on its environment to all the plugins. The
498
environment passed to plugins can be modified using the
499
<option>--global-env</option> and <option>--env-for</option>
500
options. Also, the <option>--plugin-helper-dir</option> option
501
will affect the environment variable
502
<envar>MANDOSPLUGINHELPERDIR</envar> for the plugins.
506
<refsect1 id="files">
347
507
<title>FILES</title>
352
<refsect1 id="notes">
512
>/conf/conf.d/mandos/plugin-runner.conf</filename></term>
515
Since this program will be run as a keyscript, there is
516
little to no opportunity to pass command line arguments
517
to it. Therefore, it will <emphasis>also</emphasis>
518
read this file and use its contents as
519
whitespace-separated command line options. Also,
520
everything from a <quote>#</quote> character to the end
521
of a line is ignored.
524
This program is meant to run in the initial RAM disk
525
environment, so that is where this file is assumed to
526
exist. The file does not need to exist in the normal
530
This file will be processed <emphasis>before</emphasis>
531
the normal command line options, so the latter can
532
override the former, if need be.
535
This file name is the default; the file to read for
536
arguments can be changed using the
537
<option>--config-file</option> option.
358
545
<refsect1 id="bugs">
359
546
<title>BUGS</title>
548
The <option>--config-file</option> option is ignored when
549
specified from within a configuration file.
364
553
<refsect1 id="examples">
365
554
<title>EXAMPLE</title>
557
Normal invocation needs no options:
560
<userinput>&COMMANDNAME;</userinput>
565
Run the program, but not the plugins, in debug mode:
569
<!-- do not wrap this line -->
570
<userinput>&COMMANDNAME; --debug</userinput>
576
Run all plugins, but run the <quote>foo</quote> plugin in
581
<!-- do not wrap this line -->
582
<userinput>&COMMANDNAME; --options-for=foo:--debug</userinput>
588
Run all plugins, but not the program, in debug mode:
592
<!-- do not wrap this line -->
593
<userinput>&COMMANDNAME; --global-options=--debug</userinput>
599
Read a different configuration file, run plugins from a
600
different directory, specify an alternate plugin helper
601
directory and add two options to the
602
<citerefentry><refentrytitle >mandos-client</refentrytitle>
603
<manvolnum>8mandos</manvolnum></citerefentry> plugin:
607
<!-- do not wrap this line -->
608
<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>
370
613
<refsect1 id="security">
371
614
<title>SECURITY</title>
616
This program will, when starting, try to switch to another user.
617
If it is started as root, it will succeed, and will by default
618
switch to user and group 65534, which are assumed to be
619
non-privileged. This user and group is then what all plugins
620
will be started as. Therefore, the only way to run a plugin as
621
a privileged user is to have the set-user-ID or set-group-ID bit
622
set on the plugin executable file (see <citerefentry>
623
<refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum>
627
If this program is used as a keyscript in <citerefentry
628
><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
629
</citerefentry>, there is a slight risk that if this program
630
fails to work, there might be no way to boot the system except
631
for booting from another media and editing the initial RAM disk
632
image to not run this program. This is, however, unlikely,
633
since the <citerefentry><refentrytitle
634
>password-prompt</refentrytitle><manvolnum>8mandos</manvolnum>
635
</citerefentry> plugin will read a password from the console in
636
case of failure of the other plugins, and this plugin runner
637
will also, in case of catastrophic failure, itself fall back to
638
asking and outputting a password on the console (see <xref
639
linkend="fallback"/>).
376
643
<refsect1 id="see_also">
377
644
<title>SEE ALSO</title>
646
<citerefentry><refentrytitle>intro</refentrytitle>
647
<manvolnum>8mandos</manvolnum></citerefentry>,
379
648
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
380
649
<manvolnum>8</manvolnum></citerefentry>,
650
<citerefentry><refentrytitle>crypttab</refentrytitle>
651
<manvolnum>5</manvolnum></citerefentry>,
652
<citerefentry><refentrytitle>execve</refentrytitle>
653
<manvolnum>2</manvolnum></citerefentry>,
381
654
<citerefentry><refentrytitle>mandos</refentrytitle>
382
655
<manvolnum>8</manvolnum></citerefentry>,
383
656
<citerefentry><refentrytitle>password-prompt</refentrytitle>
384
657
<manvolnum>8mandos</manvolnum></citerefentry>,
385
<citerefentry><refentrytitle>password-request</refentrytitle>
658
<citerefentry><refentrytitle>mandos-client</refentrytitle>
386
659
<manvolnum>8mandos</manvolnum></citerefentry>
391
664
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