freebsd-dev/libexec/rc/rc.d/random
Conrad Meyer 26c4978843 save-entropy(8), rc.d/random: Set nodump flag
Tag saved entropy files as "nodump," to signal that the files should not be
backed up by dump(8) or other automated backup software that honors the file
flag.

Do not produce an error if the target file resides on a filesystem that does
not support file flags (e.g., msdos /boot).

Reviewed by:	delphij
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D20358
2019-05-22 21:47:17 +00:00

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#!/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()
{
oumask=`umask`
umask 077
for f ; do
debug "saving entropy to $f"
dd if=/dev/random of="$f" bs=4096 count=1 status=none &&
( chflags nodump "$f" 2>/dev/null || : ) &&
chmod 600 "$f" &&
fsync "$f" "$(dirname "$f")"
done
umask ${oumask}
}
feed_dev_random()
{
for f ; do
if [ -f "$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 ${entropy_file_confirmed} in
'')
warn 'write failed (read-only fs?)'
;;
*)
save_dev_random "${entropy_file_confirmed}"
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 ${entropy_boot_file_confirmed} in
'')
warn 'write failed (read-only fs?)'
;;
*)
save_dev_random "${entropy_boot_file_confirmed}"
echo '.'
;;
esac
umask ${oumask}
;;
esac
}
load_rc_config $name
run_rc_command "$1"