freebsd-dev/etc/rc.d/random

#!/bin/sh
#
# $FreeBSD$
#

# PROVIDE: random
# REQUIRE: FILESYSTEMS
# BEFORE: netif
# KEYWORD: nojail shutdown

. /etc/rc.subr

name="random"
desc="Harvest and save entropy for random device"
start_cmd="random_start"
stop_cmd="random_stop"

extra_commands="saveseed"
saveseed_cmd="${name}_stop"

save_dev_random()
{
	for f ; do
		if :>>"$f" ; then
			debug "saving entropy to $f"
			dd if=/dev/random of="$f" bs=4096 count=1 2>/dev/null
		fi
	done
}

feed_dev_random()
{
	for f ; do
		if [ -f "$f" -a -r "$f" -a -s "$f" ] ; then
			if dd if="$f" of=/dev/random bs=4096 2>/dev/null ; then
				debug "entropy read from $f"
				rm -f "$f"
			fi
		fi
	done
}

random_start()
{

	if [ ${harvest_mask} -gt 0 ]; then
		echo -n 'Setting up harvesting: '
		${SYSCTL} kern.random.harvest.mask=${harvest_mask} > /dev/null
		${SYSCTL_N} kern.random.harvest.mask_symbolic
	fi

	echo -n 'Feeding entropy: '

	if [ ! -w /dev/random ] ; then
		warn "/dev/random is not writeable"
		return 1
	fi

	# Reseed /dev/random with previously stored entropy.
	case ${entropy_dir:=/var/db/entropy} in
	[Nn][Oo])
		;;
	*)
		if [ -d "${entropy_dir}" ] ; then
			feed_dev_random "${entropy_dir}"/*
		fi
		;;
	esac

	case ${entropy_file:=/entropy} in
	[Nn][Oo])
		;;
	*)
		feed_dev_random "${entropy_file}" /var/db/entropy-file
		save_dev_random "${entropy_file}"
		;;
	esac

	case ${entropy_boot_file:=/boot/entropy} in
	[Nn][Oo])
		;;
	*)
		save_dev_random "${entropy_boot_file}"
		;;
	esac

	echo '.'
}

random_stop()
{
	# Write some entropy so when the machine reboots /dev/random
	# can be reseeded
	#
	case ${entropy_file:=/entropy} in
	[Nn][Oo])
		;;
	*)
		echo -n 'Writing entropy file:'
		rm -f ${entropy_file} 2> /dev/null
		oumask=`umask`
		umask 077
		if touch ${entropy_file} 2> /dev/null; then
			entropy_file_confirmed="${entropy_file}"
		else
			# Try this as a reasonable alternative for read-only
			# roots, diskless workstations, etc.
			rm -f /var/db/entropy-file 2> /dev/null
			if touch /var/db/entropy-file 2> /dev/null; then
				entropy_file_confirmed=/var/db/entropy-file
			fi
		fi
		case ${entropy_file_confirmed} in
		'')
			warn 'write failed (read-only fs?)'
			;;
		*)
			dd if=/dev/random of=${entropy_file_confirmed} \
			    bs=4096 count=1 2> /dev/null ||
			    warn 'write failed (unwriteable file or full fs?)'
			echo '.'
			;;
		esac
		umask ${oumask}
		;;
	esac
	case ${entropy_boot_file:=/boot/entropy} in
	[Nn][Oo])
		;;
	*)
		echo -n 'Writing early boot entropy file:'
		rm -f ${entropy_boot_file} 2> /dev/null
		oumask=`umask`
		umask 077
		if touch ${entropy_boot_file} 2> /dev/null; then
			entropy_boot_file_confirmed="${entropy_boot_file}"
		fi
		case ${entropy_boot_file_confirmed} in
		'')
			warn 'write failed (read-only fs?)'
			;;
		*)
			dd if=/dev/random of=${entropy_boot_file_confirmed} \
			    bs=4096 count=1 2> /dev/null ||
			    warn 'write failed (unwriteable file or full fs?)'
			echo '.'
			;;
		esac
		umask ${oumask}
		;;
	esac
}

load_rc_config $name
run_rc_command "$1"