Add a system to save entropy from /dev/random periodically so that

it can be used to reseed at boot time. This will greatly increase
the chances that there will be sufficient entropy available at
boot time to prevent long delays.

For /etc/rc, remove the vmstat and iostat runs from the attempt
to provide some cheesy randomness if the files fail, since
those programs are dynamically linked, and ldd seems to want
some randomness to do its magic.

Guidance and parameters for this project were provided by
Mark Murray, based on the requirements of the Yarrow
algorithm. Some helpful suggestions for implementation
(including the tip about iostat and vmstat) were provided
by Sheldon Hearn. All blame for problems or mistakes is
mine of course.

3 files changed, 93 insertions, 0 deletions

diff --git a/libexec/Makefile b/libexec/Makefile
index c051e13..6ee31ed 100644
--- a/libexec/Makefile
+++ b/libexec/Makefile
@@ -22,6 +22,7 @@ SUBDIR=	atrun \
 	rpc.rwalld \
 	rpc.sprayd \
 	rshd \
+	save-entropy \
 	talkd \
 	tftpd \
 	xtend \
diff --git a/libexec/save-entropy/Makefile b/libexec/save-entropy/Makefile
new file mode 100644
index 0000000..c3de2ca
--- /dev/null
+++ b/libexec/save-entropy/Makefile
@@ -0,0 +1,10 @@
+# $FreeBSD$
+
+NOMAN=	noman
+
+beforeinstall:
+	${INSTALL} -c -o operator -g operator -m 500 \
+	    ${.CURDIR}/save-entropy.sh ${DESTDIR}${BINDIR}/save-entropy
+
+.include <bsd.prog.mk>
+
diff --git a/libexec/save-entropy/save-entropy.sh b/libexec/save-entropy/save-entropy.sh
new file mode 100755
index 0000000..4a84fd7
--- /dev/null
+++ b/libexec/save-entropy/save-entropy.sh
@@ -0,0 +1,82 @@
+#!/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.
+
+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:-/.entropy}
+	;;
+esac
+
+entropy_save_sz=${entropy_save_sz:-2048}
+entropy_save_num=${entropy_save_num:-8}
+entropy_save_jot=$(($entropy_save_num - 1))
+
+if [ ! -d "${entropy_dir}" ]; then
+	umask 077
+	mkdir "${entropy_dir}" || {
+	    logger -is 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 "${entropy_dir}"
+fi
+
+rm -f "${entropy_dir}/saved-entropy.${entropy_save_num}"
+
+umask 377
+
+for file_num in `jot ${entropy_save_jot} ${entropy_save_jot} 1`; do
+	if [ -f "${entropy_dir}/saved-entropy.${file_num}" ]; then
+		new_num=$(($file_num + 1))
+		mv "${entropy_dir}/saved-entropy.${file_num}" \
+		    "${entropy_dir}/saved-entropy.${new_num}"
+	fi
+done
+
+dd if=/dev/random of="${entropy_dir}/saved-entropy.1" \
+    bs=2048 count=1 2> /dev/null
+
+exit 0
+