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
If the password is a single-line, manually entered passprase,
420
a final trailing newline character should
421
<emphasis>not</emphasis> be printed.
424
The plugin will run in the initial RAM disk environment, so
425
care must be taken not to depend on any files or running
426
services not available there.
429
The plugin must exit cleanly and free all allocated resources
430
upon getting the TERM signal, since this is what the plugin
431
runner uses to stop all other plugins when one plugin has
432
output a password and exited cleanly.
435
The plugin must not use resources, like for instance reading
436
from the standard input, without knowing that no other plugin
440
It is useful, but not required, for the plugin to take the
441
<option>--debug</option> option.
446
<refsect1 id="fallback">
447
336
<title>FALLBACK</title>
449
If no plugins succeed, this program will, as a fallback, ask for
450
a password on the console using <citerefentry><refentrytitle
451
>getpass</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
452
and output it. This is not meant to be the normal mode of
453
operation, as there is a separate plugin for getting a password
458
340
<refsect1 id="exit_status">
459
341
<title>EXIT STATUS</title>
461
Exit status of this program is zero if no errors were
462
encountered, and otherwise not. The fallback (see <xref
463
linkend="fallback"/>) may or may not have succeeded in either
468
<refsect1 id="environment">
469
<title>ENVIRONMENT</title>
471
This program does not use any environment variables itself, it
472
only passes on its environment to all the plugins. The
473
environment passed to plugins can be modified using the
474
<option>--global-env</option> and <option>--env-for</option>
479
<refsect1 id="files">
480
347
<title>FILES</title>
485
>/conf/conf.d/mandos/plugin-runner.conf</filename></term>
488
Since this program will be run as a keyscript, there is
489
little to no opportunity to pass command line arguments
490
to it. Therefore, it will <emphasis>also</emphasis>
491
read this file and use its contents as
492
whitespace-separated command line options. Also,
493
everything from a <quote>#</quote> character to the end
494
of a line is ignored.
497
This program is meant to run in the initial RAM disk
498
environment, so that is where this file is assumed to
499
exist. The file does not need to exist in the normal
503
This file will be processed <emphasis>before</emphasis>
504
the normal command line options, so the latter can
505
override the former, if need be.
508
This file name is the default; the file to read for
509
arguments can be changed using the
510
<option>--config-file</option> option.
352
<refsect1 id="notes">
518
358
<refsect1 id="bugs">
519
359
<title>BUGS</title>
521
The <option>--config-file</option> option is ignored when
522
specified from within a configuration file.
526
364
<refsect1 id="examples">
527
365
<title>EXAMPLE</title>
530
Normal invocation needs no options:
533
<userinput>&COMMANDNAME;</userinput>
538
Run the program, but not the plugins, in debug mode:
542
<!-- do not wrap this line -->
543
<userinput>&COMMANDNAME; --debug</userinput>
549
Run all plugins, but run the <quote>foo</quote> plugin in
554
<!-- do not wrap this line -->
555
<userinput>&COMMANDNAME; --options-for=foo:--debug</userinput>
561
Run all plugins, but not the program, in debug mode:
565
<!-- do not wrap this line -->
566
<userinput>&COMMANDNAME; --global-options=--debug</userinput>
572
Run plugins from a different directory, read a different
573
configuration file, and add two options to the
574
<citerefentry><refentrytitle >mandos-client</refentrytitle>
575
<manvolnum>8mandos</manvolnum></citerefentry> plugin:
579
<!-- do not wrap this line -->
580
<userinput>&COMMANDNAME; --config-file=/etc/mandos/plugin-runner.conf --plugin-dir /usr/lib/mandos/plugins.d --options-for=mandos-client:--pubkey=/etc/keys/mandos/pubkey.txt,--seckey=/etc/keys/mandos/seckey.txt</userinput>
585
370
<refsect1 id="security">
586
371
<title>SECURITY</title>
588
This program will, when starting, try to switch to another user.
589
If it is started as root, it will succeed, and will by default
590
switch to user and group 65534, which are assumed to be
591
non-privileged. This user and group is then what all plugins
592
will be started as. Therefore, the only way to run a plugin as
593
a privileged user is to have the set-user-ID or set-group-ID bit
594
set on the plugin executable file (see <citerefentry>
595
<refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum>
599
If this program is used as a keyscript in <citerefentry
600
><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
601
</citerefentry>, there is a slight risk that if this program
602
fails to work, there might be no way to boot the system except
603
for booting from another media and editing the initial RAM disk
604
image to not run this program. This is, however, unlikely,
605
since the <citerefentry><refentrytitle
606
>password-prompt</refentrytitle><manvolnum>8mandos</manvolnum>
607
</citerefentry> plugin will read a password from the console in
608
case of failure of the other plugins, and this plugin runner
609
will also, in case of catastrophic failure, itself fall back to
610
asking and outputting a password on the console (see <xref
611
linkend="fallback"/>).
615
376
<refsect1 id="see_also">
616
377
<title>SEE ALSO</title>
618
379
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
619
380
<manvolnum>8</manvolnum></citerefentry>,
620
<citerefentry><refentrytitle>crypttab</refentrytitle>
621
<manvolnum>5</manvolnum></citerefentry>,
622
<citerefentry><refentrytitle>execve</refentrytitle>
623
<manvolnum>2</manvolnum></citerefentry>,
624
381
<citerefentry><refentrytitle>mandos</refentrytitle>
625
382
<manvolnum>8</manvolnum></citerefentry>,
626
383
<citerefentry><refentrytitle>password-prompt</refentrytitle>
627
384
<manvolnum>8mandos</manvolnum></citerefentry>,
628
<citerefentry><refentrytitle>mandos-client</refentrytitle>
385
<citerefentry><refentrytitle>password-request</refentrytitle>
629
386
<manvolnum>8mandos</manvolnum></citerefentry>
634
391
<!-- Local Variables: -->
635
392
<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->