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freebsd/libexec/save-entropy/save-entropy.sh
Doug Barton 10fe5181ec Move the process of storing entropy from /dev/random and reseeding with
it at boot time closer to the way we want it to be in the final version.

* Move the default directory to /var/db/entropy
* Run the entropy saving cron job every 11 minutes. This seems
  to be a better default, although still bikeshed material.
* Feed /dev/random some cheesy "entropy" from various commands
  and files before the disks are mounted. This gives /dev/random
  a better chance of running without blocking early.
* Move the reseeding with previously stored entropy to the point
  immediately after the disks are mounted.
* Make the harvesting script a little safer in regards to the
  possibility of accidentally overwriting something other
  than a regular file.
2001-01-14 07:18:31 +00:00

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#!/bin/sh
#
# Copyright (c) 2001 The FreeBSD Project
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
# $FreeBSD$
# This script is called by cron to store bits of randomness which are
# then used to seed /dev/random on boot.
# Originally developed by Doug Barton, DougB@FreeBSD.org
PATH=/bin:/usr/bin
# If there is a global system configuration file, suck it in.
#
if [ -r /etc/defaults/rc.conf ]; then
. /etc/defaults/rc.conf
source_rc_confs
elif [ -r /etc/rc.conf ]; then
. /etc/rc.conf
fi
case ${entropy_dir} in
[Nn][Oo])
exit 0
;;
*)
entropy_dir=${entropy_dir:-/var/db/entropy}
;;
esac
entropy_save_sz=${entropy_save_sz:-2048}
entropy_save_num=${entropy_save_num:-8}
if [ ! -d "${entropy_dir}" ]; then
umask 077
mkdir "${entropy_dir}" || {
logger -is -t "$0" The entropy directory "${entropy_dir}" does not \
exist, and cannot be created. Therefore no entropy can be saved. ;
exit 1;}
/usr/sbin/chown operator:operator "${entropy_dir}"
chmod 0700 "${entropy_dir}"
fi
umask 377
for file_num in `jot ${entropy_save_num} ${entropy_save_num} 1`; do
if [ -e "${entropy_dir}/saved-entropy.${file_num}" ]; then
if [ -f "${entropy_dir}/saved-entropy.${file_num}" ]; then
new_num=$(($file_num + 1))
if [ "${new_num}" -gt "${entropy_save_num}" ]; then
rm -f "${entropy_dir}/saved-entropy.${file_num}"
else
mv "${entropy_dir}/saved-entropy.${file_num}" \
"${entropy_dir}/saved-entropy.${new_num}"
fi
else
logger -is -t "$0" \
"${entropy_dir}/saved-entropy.${file_num} is not a regular file, and therefore \
it will not be rotated. Entropy file harvesting is aborted."
exit 1
fi
fi
done
dd if=/dev/random of="${entropy_dir}/saved-entropy.1" \
bs=2048 count=1 2> /dev/null
exit 0