PLYMOUTH(8mandos) Mandos Manual PLYMOUTH(8mandos)
NAME
plymouth - Mandos plugin to use plymouth to get a password.
SYNOPSIS
plymouth
DESCRIPTION
This program prompts for a password using plymouth(8) and outputs any given password to standard output. If no plymouth(8) process can be
found, this program will immediately exit with an exit code indicating failure.
This program is not very useful on its own. This program is really meant to run as a plugin in the Mandos client-side system, where it is
used as a fallback and alternative to retrieving passwords from a Mandos server.
If this program is killed (presumably by plugin-runner(8mandos) because some other plugin provided the password), it cannot tell
plymouth(8) to abort requesting a password, because plymouth(8) does not support this. Therefore, this program will then kill the running
plymouth(8) process and start a new one using the same command line arguments as the old one was using.
OPTIONS
This program takes no options.
EXIT STATUS
If exit status is 0, the output from the program is the password as it was read. Otherwise, if exit status is other than 0, the program was
interrupted or encountered an error, and any output so far could be corrupt and/or truncated, and should therefore be ignored.
ENVIRONMENT
cryptsource, crypttarget
If set, these environment variables will be assumed to contain the source device name and the target device mapper name, respectively,
and will be shown as part of the prompt.
These variables will normally be inherited from plugin-runner(8mandos), which will normally have inherited them from
/scripts/local-top/cryptroot in the initial RAM disk environment, which will have set them from parsing kernel arguments and
/conf/conf.d/cryptroot (also in the initial RAM disk environment), which in turn will have been created when the initial RAM disk image
was created by /usr/share/initramfs-tools/hooks/cryptroot, by extracting the information of the root file system from /etc/crypttab.
This behavior is meant to exactly mirror the behavior of askpass, the default password prompter.
FILES
/bin/plymouth
This is the command run to retrieve a password from plymouth(8).
/proc
To find the running plymouth(8), this directory will be searched for numeric entries which will be assumed to be directories. In all
those directories, the exe and cmdline entries will be used to determine the name of the running binary, effective user and group ID,
and the command line arguments. See proc(5).
/sbin/plymouthd
This is the name of the binary which will be searched for in the process list. See plymouth(8).
BUGS
Killing the plymouth(8) daemon and starting a new one is ugly, but necessary as long as it does not support aborting a password request.
EXAMPLE
Note that normally, this program will not be invoked directly, but instead started by the Mandos plugin-runner(8mandos).
This program takes no options.
plymouth
SECURITY
If this program is killed by a signal, it will kill the process ID which at the start of this program was determined to run plymouth(8) as
root (see also the section called "FILES"). There is a very slight risk that, in the time between those events, that process ID was freed
and then taken up by another process; the wrong process would then be killed. Now, this program can only be killed by the user who started
it; see plugin-runner(8mandos). This program should therefore be started by a completely separate non-privileged user, and no other
programs should be allowed to run as that special user. This means that it is not recommended to use the user "nobody" to start this
program, as other possibly less trusted programs could be running as "nobody", and they would then be able to kill this program, triggering
the killing of the process ID which may or may not be plymouth(8).
The only other thing that could be considered worthy of note is this: This program is meant to be run by plugin-runner(8mandos), and will,
when run standalone, outside, in a normal environment, immediately output on its standard output any presumably secret password it just
received. Therefore, when running this program standalone (which should never normally be done), take care not to type in any real secret
password by force of habit, since it would then immediately be shown as output.
SEE ALSO
intro(8mandos), crypttab(5), plugin-runner(8mandos), proc(5), plymouth(8)
COPYRIGHT
Copyright (C) 2010-2012 Teddy Hogeborn, Bjorn Pahlsson
This manual page 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.
This manual page 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 this program. If not, see http://www.gnu.org/licenses/.
Mandos 1.5.5 2012-01-01 PLYMOUTH(8mandos)