USPLASH(8mandos)						   Mandos Manual						  USPLASH(8mandos)

NAME

       usplash - Mandos plugin to use usplash to get a password.

SYNOPSIS

       usplash

DESCRIPTION

       This program prompts for a password using usplash(8) and outputs any given password to standard output. If no usplash(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 usplash(8)
       to abort requesting a password, because usplash(8) does not support this. Therefore, this program will then kill the running usplash(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

       /dev/.initramfs/usplash_fifo
	   This is the FIFO to where this program will write the commands for usplash(8). See fifo(7).

       /dev/.initramfs/usplash_outfifo
	   This is the FIFO where this program will read the password from usplash(8). See fifo(7).

       /proc
	   To find the running usplash(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/usplash
	   This is the name of the binary which will be searched for in the process list. See usplash(8).

BUGS

       Killing usplash(8) 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.

       usplash

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 usplash(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 usplash(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), fifo(7), plugin-runner(8mandos), proc(5), usplash(8)

COPYRIGHT

       Copyright (C) 2008-2009, 2011-2012 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							  USPLASH(8mandos)