fce6747f55
This code has had an extensive rewrite and a good series of reviews, both by the author and other parties. This means a lot of code has been simplified. Pluggable structures for high-rate entropy generators are available, and it is most definitely not the case that /dev/random can be driven by only a hardware souce any more. This has been designed out of the device. Hardware sources are stirred into the CSPRNG (Yarrow, Fortuna) like any other entropy source. Pluggable modules may be written by third parties for additional sources. The harvesting structures and consequently the locking have been simplified. Entropy harvesting is done in a more general way (the documentation for this will follow). There is some GREAT entropy to be had in the UMA allocator, but it is disabled for now as messing with that is likely to annoy many people. The venerable (but effective) Yarrow algorithm, which is no longer supported by its authors now has an alternative, Fortuna. For now, Yarrow is retained as the default algorithm, but this may be changed using a kernel option. It is intended to make Fortuna the default algorithm for 11.0. Interested parties are encouraged to read ISBN 978-0-470-47424-2 "Cryptography Engineering" By Ferguson, Schneier and Kohno for Fortuna's gory details. Heck, read it anyway. Many thanks to Arthur Mesh who did early grunt work, and who got caught in the crossfire rather more than he deserved to. My thanks also to folks who helped me thresh this out on whiteboards and in the odd "Hallway track", or otherwise. My Nomex pants are on. Let the feedback commence! Reviewed by: trasz,des(partial),imp(partial?),rwatson(partial?) Approved by: so(des)
93 lines
3.1 KiB
Bash
Executable File
93 lines
3.1 KiB
Bash
Executable File
#!/bin/sh
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#
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# Copyright (c) 2001-2006,2012 Douglas Barton, dougb@FreeBSD.org
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions
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# are met:
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# 1. Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# 2. Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in the
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# documentation and/or other materials provided with the distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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# SUCH DAMAGE.
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#
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# $FreeBSD$
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# This script is called by cron to store bits of randomness which are
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# then used to seed /dev/random on boot.
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# Originally developed by Doug Barton, dougb@FreeBSD.org
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PATH=/bin:/usr/bin
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# If there is a global system configuration file, suck it in.
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#
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if [ -r /etc/defaults/rc.conf ]; then
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. /etc/defaults/rc.conf
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source_rc_confs 2>/dev/null
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elif [ -r /etc/rc.conf ]; then
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. /etc/rc.conf 2>/dev/null
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fi
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[ $(/sbin/sysctl -n security.jail.jailed) = 0 ] || exit 0
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case ${entropy_dir} in
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[Nn][Oo])
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exit 0
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;;
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*)
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entropy_dir=${entropy_dir:-/var/db/entropy}
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;;
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esac
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entropy_save_sz=${entropy_save_sz:-4096}
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entropy_save_num=${entropy_save_num:-8}
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if [ ! -d "${entropy_dir}" ]; then
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install -d -o operator -g operator -m 0700 "${entropy_dir}" || {
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logger -is -t "$0" The entropy directory "${entropy_dir}" does \
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not exist, and cannot be created. Therefore no entropy can \
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be saved.; exit 1; }
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fi
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cd "${entropy_dir}" || {
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logger -is -t "$0" Cannot cd to the entropy directory: "${entropy_dir}". \
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Entropy file rotation is aborted.; exit 1; }
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for f in saved-entropy.*; do
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case "${f}" in saved-entropy.\*) continue ;; esac # No files match
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[ ${f#saved-entropy\.} -ge ${entropy_save_num} ] && unlink ${f}
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done
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umask 377
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n=$(( ${entropy_save_num} - 1 ))
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while [ ${n} -ge 1 ]; do
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if [ -f "saved-entropy.${n}" ]; then
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mv "saved-entropy.${n}" "saved-entropy.$(( ${n} + 1 ))"
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elif [ -e "saved-entropy.${n}" -o -L "saved-entropy.${n}" ]; then
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logger -is -t "$0" \
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"${entropy_dir}/saved-entropy.${n}" is not a regular file, and so \
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it will not be rotated. Entropy file rotation is aborted.
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exit 1
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fi
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n=$(( ${n} - 1 ))
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done
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dd if=/dev/random of=saved-entropy.1 bs=${entropy_save_sz} count=1 2>/dev/null
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exit 0
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