NetCube-Systems-Austria/kumquat-buildroot
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

package/initscripts: refactor S20urandom

Browse Source 
Adapt the format to the current template, used in other init scripts,
but do not use start/stop functions due to peculiarities.

Treat RNG initialization and random seed backup as separate operations.

Read /proc/sys/kernel/random/poolsize to calculate the pool size, as
suggestred by the urandom manual page.

Ensure that the random seed file has the correct size to prevent dumping
an empty file to /dev/urandom on the first boot.

Save the seed at /var/lib/random-seed as other non-systemd distributions
do (e.g.  RHEL6), since /etc can be in a red-only rootfs. The Filesystem
Hierarchy Standard defines that /var/lib holds persistent data modified
by programs as they run.

Users willing to use a different path just need to redefine URANDOM_SEED
in /etc/default/urandom instead of rewriting the init script.

[Peter: save/restore umask]
Signed-off-by: Carlos Santos <unixmania@gmail.com>
Tested-by: Matthew Weber <matthew.weber@rockwellcollins.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
This commit is contained in:
Carlos Santos 2019-10-24 11:01:51 -03:00 committed by Peter Korsgaard
parent 43372c21b7
commit d9e5c2b627
1 changed files with 63 additions and 40 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

103
package/initscripts/init.d/S20urandom
View File

@ -1,51 +1,74 @@
#! /bin/sh
#
# urandom This script saves the random seed between reboots.
# It is called from the boot, halt and reboot scripts.
#
# Version: @(#)urandom 1.33 22-Jun-1998 miquels@cistron.nl
# Preserve the random seed between reboots. See urandom(4).
#
# Quietly do nothing if /dev/urandom does not exist
[ -c /dev/urandom ] || exit 0
#. /etc/default/rcS
URANDOM_SEED="/var/lib/random-seed"
# shellcheck source=/dev/null
[ -r "/etc/default/urandom" ] && . "/etc/default/urandom"
if pool_bits=$(cat /proc/sys/kernel/random/poolsize 2> /dev/null); then
pool_size=$((pool_bits/8))
else
pool_size=512
fi
check_file_size() {
[ -f "$URANDOM_SEED" ] || return 1
# Try to read two blocks but exactly one will be read if the file has
# the correct size.
size=$(dd if="$URANDOM_SEED" bs="$pool_size" count=2 2> /dev/null | wc -c)
test "$size" -eq "$pool_size"
}
init_rng() {
if check_file_size; then
printf 'Initializing random number generator: '
dd if="$URANDOM_SEED" bs="$pool_size" of=/dev/urandom count=1 2> /dev/null
status=$?
if [ "$status" -eq 0 ]; then
echo "OK"
else
echo "FAIL"
fi
return "$status"
fi
}
save_random_seed() {
printf 'Saving random seed: '
if touch "$URANDOM_SEED" 2> /dev/null; then
old_umask=$(umask)
umask 077
dd if=/dev/urandom of="$URANDOM_SEED" bs="$pool_size" count=1 2> /dev/null
status=$?
umask "$old_umask"
if [ "$status" -eq 0 ]; then
echo "OK"
else
echo "FAIL"
fi
else
status=$?
echo "SKIP (read-only file system detected)"
fi
return "$status"
}
case "$1" in
start|"")
# check for read only file system
if ! touch /etc/random-seed 2>/dev/null
then
echo "read-only file system detected...done"
exit
fi
if [ "$VERBOSE" != no ]
then
printf "Initializing random number generator... "
fi
# Load and then save 512 bytes,
# which is the size of the entropy pool
cat /etc/random-seed >/dev/urandom
rm -f /etc/random-seed
umask 077
dd if=/dev/urandom of=/etc/random-seed count=1 \
>/dev/null 2>&1 || echo "urandom start: failed."
umask 022
[ "$VERBOSE" != no ] && echo "done."
;;
start|restart|reload)
# Carry a random seed from start-up to start-up
# Load and then save the whole entropy pool
init_rng && save_random_seed;;
stop)
if ! touch /etc/random-seed 2>/dev/null
then
exit
fi
# Carry a random seed from shut-down to start-up;
# see documentation in linux/drivers/char/random.c
[ "$VERBOSE" != no ] && printf "Saving random seed... "
umask 077
dd if=/dev/urandom of=/etc/random-seed count=1 \
>/dev/null 2>&1 || echo "urandom stop: failed."
[ "$VERBOSE" != no ] && echo "done."
;;
# Carry a random seed from shut-down to start-up
# Save the whole entropy pool
save_random_seed;;
*)
echo "Usage: urandom {start|stop}" >&2
echo "Usage: $0 {start|stop|restart|reload}"
exit 1
;;
esac