save-entropy.sh revision 70922 
1#!/bin/sh
2#
3# Copyright (c) 2001  The FreeBSD Project
4# All rights reserved.
5#
6# Redistribution and use in source and binary forms, with or without
7# modification, are permitted provided that the following conditions
8# are met:
9# 1. Redistributions of source code must retain the above copyright
10#    notice, this list of conditions and the following disclaimer.
11# 2. Redistributions in binary form must reproduce the above copyright
12#    notice, this list of conditions and the following disclaimer in the
13#    documentation and/or other materials provided with the distribution.
14#
15# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25# SUCH DAMAGE.
26#
27# $FreeBSD: head/libexec/save-entropy/save-entropy.sh 70922 2001-01-11 13:01:20Z dougb $
28
29# This script is called by cron to store bits of randomness which are
30# then used to seed /dev/random on boot.
31
32PATH=/bin:/usr/bin
33
34# If there is a global system configuration file, suck it in.
35#
36if [ -r /etc/defaults/rc.conf ]; then
37	. /etc/defaults/rc.conf
38	source_rc_confs
39elif [ -r /etc/rc.conf ]; then
40	. /etc/rc.conf
41fi
42
43case ${entropy_dir} in
44[Nn][Oo])
45	exit 0
46	;;
47*)
48	entropy_dir=${entropy_dir:-/.entropy}
49	;;
50esac
51
52entropy_save_sz=${entropy_save_sz:-2048}
53entropy_save_num=${entropy_save_num:-8}
54entropy_save_jot=$(($entropy_save_num - 1))
55
56if [ ! -d "${entropy_dir}" ]; then
57	umask 077
58	mkdir "${entropy_dir}" || {
59	    logger -is The entropy directory "${entropy_dir}" does not \
60exist, and cannot be created.  Therefore no entropy can be saved. ;
61	    exit 1;}
62	/usr/sbin/chown operator:operator "${entropy_dir}"
63	chmod 0700 "${entropy_dir}"
64fi
65
66rm -f "${entropy_dir}/saved-entropy.${entropy_save_num}"
67
68umask 377
69
70for file_num in `jot ${entropy_save_jot} ${entropy_save_jot} 1`; do
71	if [ -f "${entropy_dir}/saved-entropy.${file_num}" ]; then
72		new_num=$(($file_num + 1))
73		mv "${entropy_dir}/saved-entropy.${file_num}" \
74		    "${entropy_dir}/saved-entropy.${new_num}"
75	fi
76done
77
78dd if=/dev/random of="${entropy_dir}/saved-entropy.1" \
79    bs=2048 count=1 2> /dev/null
80
81exit 0
82
83