Provided by: mandos-client_1.8.14-1_amd64 
NAME
plugin-runner - Run Mandos plugins, pass data from first to succeed.
SYNOPSIS
plugin-runner [--global-env=ENV=value | -G ENV=value ...]
[--env-for=PLUGIN:ENV=value | -E PLUGIN:ENV=value ...]
[--global-options=OPTIONS | -g OPTIONS ...]
[--options-for=PLUGIN:OPTIONS | -o PLUGIN:OPTIONS ...]
[--disable=PLUGIN | -d PLUGIN ...]
[--enable=PLUGIN | -e PLUGIN ...]
[--groupid=ID]
[--userid=ID]
[--plugin-dir=DIRECTORY]
[--plugin-helper-dir=DIRECTORY]
[--config-file=FILE]
[--debug]
plugin-runner {--help | -?}
plugin-runner --usage
plugin-runner {--version | -V}
DESCRIPTION
plugin-runner is a program which is meant to be specified as a “keyscript” for the root
disk in crypttab(5). The aim of this program is therefore to output a password, which then
cryptsetup(8) will use to unlock the root disk.
This program is not meant to be invoked directly, but can be in order to test it. Note
that any password obtained will simply be output on standard output.
PURPOSE
The purpose of this is to enable remote and unattended rebooting of client host computer
with an encrypted root file system. See the section called “OVERVIEW” for details.
OPTIONS
--global-env ENV=value, -G ENV=value
This option will add an environment variable setting to all plugins. This will
override any inherited environment variable.
--env-for PLUGIN:ENV=value, -E PLUGIN:ENV=value
This option will add an environment variable setting to the PLUGIN plugin. This will
override any inherited environment variables or environment variables specified using
--global-env.
--global-options OPTIONS, -g OPTIONS
Pass some options to all plugins. OPTIONS is a comma separated list of options. This
is not a very useful option, except for specifying the “--debug” option to all
plugins.
--options-for PLUGIN:OPTION, -o PLUGIN:OPTION
Pass some options to a specific plugin. PLUGIN is the name (file basename) of a
plugin, and OPTIONS is a comma separated list of options.
Note that since options are not split on whitespace, the way to pass, to the plugin
“foo”, the option --bar with the option argument “baz” is either
--options-for=foo:--bar=baz or --options-for=foo:--bar,baz. Using
--options-for="foo:--bar baz". will not work.
--disable PLUGIN, -d PLUGIN
Disable the plugin named PLUGIN. The plugin will not be started.
--enable PLUGIN, -e PLUGIN
Re-enable the plugin named PLUGIN. This is only useful to undo a previous --disable
option, maybe from the configuration file.
--groupid ID
Change to group ID ID on startup. The default is 65534. All plugins will be started
using this group ID. Note: This must be a number, not a name.
--userid ID
Change to user ID ID on startup. The default is 65534. All plugins will be started
using this user ID. Note: This must be a number, not a name.
--plugin-dir DIRECTORY
Specify a different plugin directory. The default is /lib/mandos/plugins.d, which will
exist in the initial RAM disk environment.
--plugin-helper-dir DIRECTORY
Specify a different plugin helper directory. The default is
/lib/mandos/plugin-helpers, which will exist in the initial RAM disk environment.
(This will simply be passed to all plugins via the MANDOSPLUGINHELPERDIR environment
variable. See the section called “WRITING PLUGINS”)
--config-file FILE
Specify a different file to read additional options from. See the section called
“FILES”. Other command line options will override options specified in the file.
--debug
Enable debug mode. This will enable a lot of output to standard error about what the
program is doing. The program will still perform all other functions normally. The
default is to not run in debug mode.
The plugins will not be affected by this option. Use --global-options=--debug if
complete debugging eruption is desired.
--help, -?
Gives a help message about options and their meanings.
--usage
Gives a short usage message.
--version, -V
Prints the program version.
OVERVIEW
This is part of the Mandos system for allowing computers to have encrypted root file
systems and at the same time be capable of remote and/or unattended reboots. The computers
run a small client program in the initial RAM disk environment which will communicate with
a server over a network. All network communication is encrypted using TLS. The clients are
identified by the server using a TLS key; each client has one unique to it. The server
sends the clients an encrypted password. The encrypted password is decrypted by the
clients using a separate OpenPGP key, and the password is then used to unlock the root
file system, whereupon the computers can continue booting normally.
This program will run on the client side in the initial RAM disk environment, and is
responsible for getting a password. It does this by running plugins, one of which will
normally be the actual client program communicating with the server.
PLUGINS
This program will get a password by running a number of plugins, which are simply
executable programs in a directory in the initial RAM disk environment. The default
directory is /lib/mandos/plugins.d, but this can be changed with the --plugin-dir option.
The plugins are started in parallel, and the first plugin to output a password and exit
with a successful exit code will make this plugin-runner output the password from that
plugin, stop any other plugins, and exit.
WRITING PLUGINS
A plugin is simply a program which prints a password to its standard output and then exits
with a successful (zero) exit status. If the exit status is not zero, any output on
standard output will be ignored by the plugin runner. Any output on its standard error
channel will simply be passed to the standard error of the plugin runner, usually the
system console.
If the password is a single-line, manually entered passprase, a final trailing newline
character should not be printed.
The plugin will run in the initial RAM disk environment, so care must be taken not to
depend on any files or running services not available there. Any helper executables
required by the plugin (which are not in the PATH) can be placed in the plugin helper
directory, the name of which will be made available to the plugin via the
MANDOSPLUGINHELPERDIR environment variable.
The plugin must exit cleanly and free all allocated resources upon getting the TERM
signal, since this is what the plugin runner uses to stop all other plugins when one
plugin has output a password and exited cleanly.
The plugin must not use resources, like for instance reading from the standard input,
without knowing that no other plugin is also using it.
It is useful, but not required, for the plugin to take the --debug option.
FALLBACK
If no plugins succeed, this program will, as a fallback, ask for a password on the console
using getpass(3), and output it. This is not meant to be the normal mode of operation, as
there is a separate plugin for getting a password from the console.
EXIT STATUS
Exit status of this program is zero if no errors were encountered, and otherwise not. The
fallback (see the section called “FALLBACK”) may or may not have succeeded in either case.
ENVIRONMENT
This program does not use any environment variables itself, it only passes on its
environment to all the plugins. The environment passed to plugins can be modified using
the --global-env and --env-for options. Also, the --plugin-helper-dir option will affect
the environment variable MANDOSPLUGINHELPERDIR for the plugins.
FILES
/conf/conf.d/mandos/plugin-runner.conf
Since this program will be run as a keyscript, there is little to no opportunity to
pass command line arguments to it. Therefore, it will also read this file and use its
contents as whitespace-separated command line options. Also, everything from a “#”
character to the end of a line is ignored.
This program is meant to run in the initial RAM disk environment, so that is where
this file is assumed to exist. The file does not need to exist in the normal file
system.
This file will be processed before the normal command line options, so the latter can
override the former, if need be.
This file name is the default; the file to read for arguments can be changed using the
--config-file option.
/lib/mandos/plugins.d
The default plugin directory; can be changed by the --plugin-dir option.
/lib/mandos/plugin-helpers
The default plugin helper directory; can be changed by the --plugin-helper-dir option.
BUGS
The --config-file option is ignored when specified from within a configuration file.
Please report bugs to the Mandos development mailing list: <mandos-dev@recompile.se>
(subscription required). Note that this list is public. The developers can be reached
privately at <mandos@recompile.se> (OpenPGP key fingerprint 153A 37F1 0BBA 0435 987F 2C4A
7223 2973 CA34 C2C4 for encrypted mail).
EXAMPLE
Normal invocation needs no options:
plugin-runner
Run the program, but not the plugins, in debug mode:
plugin-runner --debug
Run all plugins, but run the “foo” plugin in debug mode:
plugin-runner --options-for=foo:--debug
Run all plugins, but not the program, in debug mode:
plugin-runner --global-options=--debug
Read a different configuration file, run plugins from a different directory, specify an
alternate plugin helper directory and add four options to the mandos-client(8mandos)
plugin:
cd /etc/keys/mandos; plugin-runner --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,
--tls-pubkey=tls-pubkey.pem,--tls-privkey=tls-privkey.pem
SECURITY
This program will, when starting, try to switch to another user. If it is started as root,
it will succeed, and will by default switch to user and group 65534, which are assumed to
be non-privileged. This user and group is then what all plugins will be started as.
Therefore, the only way to run a plugin as a privileged user is to have the set-user-ID or
set-group-ID bit set on the plugin executable file (see execve(2)).
If this program is used as a keyscript in crypttab(5), there is a slight risk that if this
program fails to work, there might be no way to boot the system except for booting from
another media and editing the initial RAM disk image to not run this program. This is,
however, unlikely, since the password-prompt(8mandos) plugin will read a password from the
console in case of failure of the other plugins, and this plugin runner will also, in case
of catastrophic failure, itself fall back to asking and outputting a password on the
console (see the section called “FALLBACK”).
SEE ALSO
intro(8mandos), cryptsetup(8), crypttab(5), execve(2), mandos(8), password-
prompt(8mandos), mandos-client(8mandos)
COPYRIGHT
Copyright © 2008-2019 Teddy Hogeborn, Björn Påhlsson
This manual page is part of Mandos.
Mandos is free software: you can redistribute it and/or modify it under the terms of the
GNU General Public License as published by the Free Software Foundation, either version 3
of the License, or (at your option) any later version.
Mandos is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with Mandos. If
not, see http://www.gnu.org/licenses/.