save-entropy.sh revision 269220 
1#!/bin/sh
2#
3# Copyright (c) 2001-2006,2012 Douglas Barton, dougb@FreeBSD.org
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: stable/10/libexec/save-entropy/save-entropy.sh 269220 2014-07-29 06:00:16Z delphij $
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
32# Originally developed by Doug Barton, dougb@FreeBSD.org
33
34PATH=/bin:/usr/bin
35
36# If there is a global system configuration file, suck it in.
37#
38if [ -r /etc/defaults/rc.conf ]; then
39	. /etc/defaults/rc.conf
40	source_rc_confs 2>/dev/null
41elif [ -r /etc/rc.conf ]; then
42	. /etc/rc.conf 2>/dev/null
43fi
44
45[ $(/sbin/sysctl -n security.jail.jailed) = 0 ] || exit 0
46
47case ${entropy_dir} in
48[Nn][Oo])
49	exit 0
50	;;
51*)
52	entropy_dir=${entropy_dir:-/var/db/entropy}
53	;;
54esac
55
56entropy_save_sz=${entropy_save_sz:-2048}
57entropy_save_num=${entropy_save_num:-8}
58
59if [ ! -d "${entropy_dir}" ]; then
60	install -d -o operator -g operator -m 0700 "${entropy_dir}" || {
61		logger -is -t "$0" The entropy directory "${entropy_dir}" does \
62		    not exist, and cannot be created. Therefore no entropy can \
63		    be saved.; exit 1; }
64fi
65
66cd "${entropy_dir}" || {
67	logger -is -t "$0" Cannot cd to the entropy directory: "${entropy_dir}". \
68	    Entropy file rotation is aborted.; exit 1; }
69
70for f in saved-entropy.*; do
71	case "${f}" in saved-entropy.\*) continue ;; esac	# No files match
72	[ ${f#saved-entropy\.} -ge ${entropy_save_num} ] && unlink ${f}
73done
74
75umask 377
76
77n=$(( ${entropy_save_num} - 1 ))
78while [ ${n} -ge 1 ]; do
79	if [ -f "saved-entropy.${n}" ]; then
80		mv "saved-entropy.${n}" "saved-entropy.$(( ${n} + 1 ))"
81	elif [ -e "saved-entropy.${n}" -o -L "saved-entropy.${n}" ]; then
82		logger -is -t "$0" \
83	"${entropy_dir}/saved-entropy.${n}" is not a regular file, and so \
84	    it will not be rotated. Entropy file rotation is aborted.
85		exit 1
86	fi
87	n=$(( ${n} - 1 ))
88done
89
90dd if=/dev/random of=saved-entropy.1 bs=${entropy_save_sz} count=1 2>/dev/null
91
92exit 0
93