| #!/bin/sh |
| # |
| # SPDX-License-Identifier: GPL-2.0-only |
| # |
| |
| ### BEGIN INIT INFO |
| # Provides: urandom |
| # Required-Start: $local_fs mountvirtfs |
| # Required-Stop: $local_fs |
| # Default-Start: S |
| # Default-Stop: 0 6 |
| # Short-Description: Save and restore the random seed |
| # Description: Save the random seed on shutdown and restore it on boot, |
| # to ensure that the seed isn't predicable on startup |
| # (because the boot process is predictable) |
| ### END INIT INFO |
| |
| test -c /dev/urandom || exit 0 |
| |
| RANDOM_SEED_FILE=/var/lib/urandom/random-seed |
| |
| . /etc/default/rcS |
| [ -f /etc/default/urandom ] && . /etc/default/urandom |
| |
| case "$1" in |
| start|"") |
| test "$VERBOSE" != no && echo "Initializing random number generator..." |
| # Load and then save 512 bytes, which is the size of the entropy |
| # pool. Also load the current date, in case the seed file is |
| # empty. |
| ( date +%s.%N; [ -f "$RANDOM_SEED_FILE" ] && cat "$RANDOM_SEED_FILE" ) \ |
| >/dev/urandom |
| rm -f "$RANDOM_SEED_FILE" |
| umask 077 |
| dd if=/dev/urandom of=$RANDOM_SEED_FILE count=1 \ |
| >/dev/null 2>&1 || echo "urandom start: failed." |
| umask 022 |
| ;; |
| stop) |
| # Carry a random seed from shut-down to start-up; |
| # see documentation in linux/drivers/char/random.c |
| test "$VERBOSE" != no && echo "Saving random seed..." |
| umask 077 |
| dd if=/dev/urandom of=$RANDOM_SEED_FILE count=1 \ |
| >/dev/null 2>&1 || echo "urandom stop: failed." |
| ;; |
| *) |
| echo "Usage: urandom {start|stop}" >&2 |
| exit 1 |
| ;; |
| esac |
| |
| exit 0 |