Use seedrng for seeding the random number generator
The RNG can't actually be seeded from a shell script, due to the reliance on ioctls. For this reason, the seedrng project provides a basic script meant to be copy and pasted into projects like OpenRC and tweaked as needed: https://git.zx2c4.com/seedrng/about/ This commit imports it into OpenRC and wires up /etc/init.d/urandom to call it. It shouldn't be called by other things on the system, so it lives in rc_sbindir. Closes #506. Closes #507. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld
William Hubbs
parent
270e5c6828
commit
076c2552ae
1
AUTHORS
1
AUTHORS
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@ -43,6 +43,7 @@ Ian Stakenvicius <axs@gentoo.org>
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Jakob Drexel <jake42@rommel.stw.uni-erlangen.de>
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James Le Cuirot <chewi@aura-online.co.uk>
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Jan Psota <jasiu@belsznica.pl>
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Jason A. Donenfeld <Jason@zx2c4.com>
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Jason Zaman <jason@perfinion.com>
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Joe Harvell <jharvell@dogpad.net>
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Joe M <joe9mail@gmail.com>
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@ -2,4 +2,11 @@
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# (say for crypt swap), so you will need to customize this
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# behavior. If you have /var on a separate partition, then
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# make sure this path lives on your root device somewhere.
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urandom_seed="/var/lib/misc/random-seed"
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seed_dir="/var/lib/seedrng"
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lock_file="/var/run/seedrng.lock"
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# Set this to true if you do not want seed files to actually
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# credit the RNG. Set this if you plan to replicate this
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# file system image and do not have the wherewithal to first
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# delete the contents of /var/lib/seedrng.
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skip_credit="false"
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@ -1,5 +1,5 @@
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#!@SBINDIR@/openrc-run
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# Copyright (c) 2007-2015 The OpenRC Authors.
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# Copyright (c) 2007-2022 The OpenRC Authors.
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# See the Authors file at the top-level directory of this distribution and
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# https://github.com/OpenRC/openrc/blob/HEAD/AUTHORS
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#
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@ -9,7 +9,10 @@
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# This file may not be copied, modified, propagated, or distributed
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# except according to the terms contained in the LICENSE file.
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: ${urandom_seed:=${URANDOM_SEED:-/var/lib/misc/random-seed}}
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export SEEDRNG_SEED_DIR="${seed_dir:-/var/lib/seedrng}"
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export SEEDRNG_LOCK_FILE="${lock_file:-/var/run/seedrng.lock}"
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export SEEDRNG_SKIP_CREDIT="${skip_credit:-false}"
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: ${urandom_seed:=${SEEDRNG_SEED_DIR}/../misc/random-seed}
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description="Initializes the random number generator."
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depend()
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@ -21,33 +24,35 @@ depend()
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save_seed()
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{
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local psz=1
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if [ -e /proc/sys/kernel/random/poolsize ]; then
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: $(( psz = $(cat /proc/sys/kernel/random/poolsize) / 4096 ))
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fi
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( # sub shell to prevent umask pollution
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umask 077
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dd if=/dev/urandom of="$urandom_seed" count=${psz} 2>/dev/null
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dd if=/dev/urandom of="$urandom_seed" count=1 2>/dev/null
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)
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}
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start()
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{
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[ -c /dev/urandom ] || return
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if [ -f "$urandom_seed" ]; then
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ebegin "Initializing random number generator"
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cat "$urandom_seed" > /dev/urandom
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eend $? "Error initializing random number generator"
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if [ "$RC_UNAME" = Linux ]; then
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seedrng
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else
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[ -c /dev/urandom ] || return
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if [ -f "$urandom_seed" ]; then
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ebegin "Initializing random number generator"
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cat "$urandom_seed" > /dev/urandom
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eend $? "Error initializing random number generator"
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fi
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rm -f "$urandom_seed" && save_seed
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fi
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rm -f "$urandom_seed" && save_seed
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return 0
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}
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stop()
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{
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ebegin "Saving random seed"
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save_seed
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eend $? "Failed to save random seed"
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if [ "$RC_UNAME" = Linux ]; then
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seedrng
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else
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ebegin "Saving random seed"
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save_seed
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eend $? "Failed to save random seed"
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fi
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}
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@ -15,7 +15,7 @@ endif
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ifeq (${OS},Linux)
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SRCS+= kill_all.c openrc-init.c openrc-shutdown.c rc-sysvinit.c broadcast.c \
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rc-wtmp.c
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rc-wtmp.c seedrng.c
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endif
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CLEANFILES= version.h rc-selinux.o
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@ -47,6 +47,7 @@ RC_SBINPROGS= mark_service_starting mark_service_started \
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ifeq (${OS},Linux)
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RC_BINPROGS+= kill_all
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RC_SBINPROGS+= seedrng
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SBINPROGS+= openrc-init openrc-shutdown
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endif
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@ -180,3 +181,6 @@ shell_var: shell_var.o
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swclock: swclock.o _usage.o rc-misc.o
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${CC} ${LOCAL_CFLAGS} ${LOCAL_LDFLAGS} ${CFLAGS} ${LDFLAGS} -o $@ $^ ${LDADD}
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seedrng: seedrng.o
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${CC} ${LOCAL_CFLAGS} ${LOCAL_LDFLAGS} ${CFLAGS} ${LDFLAGS} -o $@ $^ ${LDADD}
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@ -268,7 +268,15 @@ if os == 'Linux'
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link_with: [libeinfo,librc],
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install: true,
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install_dir: rc_bindir)
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endif
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executable('seedrng',
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['seedrng.c'],
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c_args : cc_branding_flags,
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include_directories: [incdir, einfo_incdir, rc_incdir],
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link_with: [libeinfo, librc],
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install: true,
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install_dir: rc_sbindir)
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endif
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executable('shell_var',
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['shell_var.c'],
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@ -0,0 +1,453 @@
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/*
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* seedrng.c
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* Seed kernel RNG from seed file, based on code from:
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* https://git.zx2c4.com/seedrng/about/
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*/
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/*
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* Copyright (c) 2022 The OpenRC Authors.
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* See the Authors file at the top-level directory of this distribution and
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* https://github.com/OpenRC/openrc/blob/HEAD/AUTHORS
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*
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* This file is part of OpenRC. It is subject to the license terms in
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* the LICENSE file found in the top-level directory of this
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* distribution and at https://github.com/OpenRC/openrc/blob/HEAD/LICENSE
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* This file may not be copied, modified, propagated, or distributed
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* except according to the terms contained in the LICENSE file.
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*/
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#include <linux/random.h>
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#include <sys/random.h>
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#include <sys/ioctl.h>
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#include <sys/file.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <fcntl.h>
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#include <poll.h>
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#include <unistd.h>
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#include <time.h>
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#include <errno.h>
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#include <endian.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include <string.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "rc.h"
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#include "einfo.h"
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#include "helpers.h"
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#ifndef GRND_INSECURE
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#define GRND_INSECURE 0x0004 /* Apparently some headers don't ship with this yet. */
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#endif
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static const char *SEED_DIR;
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static const char *LOCK_FILE;
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static char *CREDITABLE_SEED;
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static char *NON_CREDITABLE_SEED;
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enum blake2s_lengths {
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BLAKE2S_BLOCK_LEN = 64,
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BLAKE2S_HASH_LEN = 32,
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BLAKE2S_KEY_LEN = 32
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};
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enum seedrng_lengths {
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MAX_SEED_LEN = 512,
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MIN_SEED_LEN = BLAKE2S_HASH_LEN
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};
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struct blake2s_state {
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uint32_t h[8];
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uint32_t t[2];
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uint32_t f[2];
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uint8_t buf[BLAKE2S_BLOCK_LEN];
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unsigned int buflen;
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unsigned int outlen;
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};
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#define le32_to_cpup(a) le32toh(*(a))
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#define cpu_to_le32(a) htole32(a)
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#ifndef ARRAY_SIZE
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#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
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#endif
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#ifndef DIV_ROUND_UP
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#define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
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#endif
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static inline void cpu_to_le32_array(uint32_t *buf, unsigned int words)
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{
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while (words--) {
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*buf = cpu_to_le32(*buf);
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++buf;
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}
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}
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static inline void le32_to_cpu_array(uint32_t *buf, unsigned int words)
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{
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while (words--) {
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*buf = le32_to_cpup(buf);
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++buf;
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}
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}
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static inline uint32_t ror32(uint32_t word, unsigned int shift)
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{
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return (word >> (shift & 31)) | (word << ((-shift) & 31));
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}
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static const uint32_t blake2s_iv[8] = {
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0x6A09E667UL, 0xBB67AE85UL, 0x3C6EF372UL, 0xA54FF53AUL,
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0x510E527FUL, 0x9B05688CUL, 0x1F83D9ABUL, 0x5BE0CD19UL
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};
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static const uint8_t blake2s_sigma[10][16] = {
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{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 },
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{ 14, 10, 4, 8, 9, 15, 13, 6, 1, 12, 0, 2, 11, 7, 5, 3 },
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{ 11, 8, 12, 0, 5, 2, 15, 13, 10, 14, 3, 6, 7, 1, 9, 4 },
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{ 7, 9, 3, 1, 13, 12, 11, 14, 2, 6, 5, 10, 4, 0, 15, 8 },
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{ 9, 0, 5, 7, 2, 4, 10, 15, 14, 1, 11, 12, 6, 8, 3, 13 },
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{ 2, 12, 6, 10, 0, 11, 8, 3, 4, 13, 7, 5, 15, 14, 1, 9 },
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{ 12, 5, 1, 15, 14, 13, 4, 10, 0, 7, 6, 3, 9, 2, 8, 11 },
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{ 13, 11, 7, 14, 12, 1, 3, 9, 5, 0, 15, 4, 8, 6, 2, 10 },
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{ 6, 15, 14, 9, 11, 3, 0, 8, 12, 2, 13, 7, 1, 4, 10, 5 },
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{ 10, 2, 8, 4, 7, 6, 1, 5, 15, 11, 9, 14, 3, 12, 13, 0 },
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};
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static void blake2s_set_lastblock(struct blake2s_state *state)
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{
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state->f[0] = -1;
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}
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static void blake2s_increment_counter(struct blake2s_state *state, const uint32_t inc)
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{
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state->t[0] += inc;
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state->t[1] += (state->t[0] < inc);
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}
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static void blake2s_init_param(struct blake2s_state *state, const uint32_t param)
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{
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int i;
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memset(state, 0, sizeof(*state));
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for (i = 0; i < 8; ++i)
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state->h[i] = blake2s_iv[i];
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state->h[0] ^= param;
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}
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static void blake2s_init(struct blake2s_state *state, const size_t outlen)
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{
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blake2s_init_param(state, 0x01010000 | outlen);
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state->outlen = outlen;
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}
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static void blake2s_compress(struct blake2s_state *state, const uint8_t *block, size_t nblocks, const uint32_t inc)
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{
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uint32_t m[16];
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uint32_t v[16];
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int i;
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while (nblocks > 0) {
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blake2s_increment_counter(state, inc);
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memcpy(m, block, BLAKE2S_BLOCK_LEN);
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le32_to_cpu_array(m, ARRAY_SIZE(m));
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memcpy(v, state->h, 32);
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v[ 8] = blake2s_iv[0];
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v[ 9] = blake2s_iv[1];
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v[10] = blake2s_iv[2];
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v[11] = blake2s_iv[3];
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v[12] = blake2s_iv[4] ^ state->t[0];
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v[13] = blake2s_iv[5] ^ state->t[1];
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v[14] = blake2s_iv[6] ^ state->f[0];
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v[15] = blake2s_iv[7] ^ state->f[1];
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#define G(r, i, a, b, c, d) do { \
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a += b + m[blake2s_sigma[r][2 * i + 0]]; \
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d = ror32(d ^ a, 16); \
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c += d; \
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b = ror32(b ^ c, 12); \
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a += b + m[blake2s_sigma[r][2 * i + 1]]; \
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d = ror32(d ^ a, 8); \
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c += d; \
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b = ror32(b ^ c, 7); \
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} while (0)
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#define ROUND(r) do { \
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G(r, 0, v[0], v[ 4], v[ 8], v[12]); \
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G(r, 1, v[1], v[ 5], v[ 9], v[13]); \
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G(r, 2, v[2], v[ 6], v[10], v[14]); \
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G(r, 3, v[3], v[ 7], v[11], v[15]); \
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G(r, 4, v[0], v[ 5], v[10], v[15]); \
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G(r, 5, v[1], v[ 6], v[11], v[12]); \
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G(r, 6, v[2], v[ 7], v[ 8], v[13]); \
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G(r, 7, v[3], v[ 4], v[ 9], v[14]); \
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} while (0)
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ROUND(0);
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ROUND(1);
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ROUND(2);
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ROUND(3);
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ROUND(4);
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ROUND(5);
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ROUND(6);
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ROUND(7);
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ROUND(8);
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ROUND(9);
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#undef G
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#undef ROUND
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for (i = 0; i < 8; ++i)
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state->h[i] ^= v[i] ^ v[i + 8];
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block += BLAKE2S_BLOCK_LEN;
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--nblocks;
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}
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}
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static void blake2s_update(struct blake2s_state *state, const void *inp, size_t inlen)
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{
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const size_t fill = BLAKE2S_BLOCK_LEN - state->buflen;
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const uint8_t *in = inp;
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if (!inlen)
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return;
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if (inlen > fill) {
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memcpy(state->buf + state->buflen, in, fill);
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blake2s_compress(state, state->buf, 1, BLAKE2S_BLOCK_LEN);
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state->buflen = 0;
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in += fill;
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inlen -= fill;
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}
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if (inlen > BLAKE2S_BLOCK_LEN) {
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const size_t nblocks = DIV_ROUND_UP(inlen, BLAKE2S_BLOCK_LEN);
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blake2s_compress(state, in, nblocks - 1, BLAKE2S_BLOCK_LEN);
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in += BLAKE2S_BLOCK_LEN * (nblocks - 1);
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inlen -= BLAKE2S_BLOCK_LEN * (nblocks - 1);
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}
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memcpy(state->buf + state->buflen, in, inlen);
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state->buflen += inlen;
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}
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static void blake2s_final(struct blake2s_state *state, uint8_t *out)
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{
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blake2s_set_lastblock(state);
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memset(state->buf + state->buflen, 0, BLAKE2S_BLOCK_LEN - state->buflen);
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blake2s_compress(state, state->buf, 1, state->buflen);
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cpu_to_le32_array(state->h, ARRAY_SIZE(state->h));
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memcpy(out, state->h, state->outlen);
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}
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static size_t determine_optimal_seed_len(void)
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{
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size_t ret = 0;
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char poolsize_str[11] = { 0 };
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int fd = open("/proc/sys/kernel/random/poolsize", O_RDONLY);
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if (fd < 0 || read(fd, poolsize_str, sizeof(poolsize_str) - 1) < 0) {
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ewarn("Unable to determine pool size, falling back to %u bits: %s", MIN_SEED_LEN * 8, strerror(errno));
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ret = MIN_SEED_LEN;
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} else
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ret = DIV_ROUND_UP(strtoul(poolsize_str, NULL, 10), 8);
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if (fd >= 0)
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close(fd);
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if (ret < MIN_SEED_LEN)
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ret = MIN_SEED_LEN;
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else if (ret > MAX_SEED_LEN)
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ret = MAX_SEED_LEN;
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return ret;
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}
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static int read_new_seed(uint8_t *seed, size_t len, bool *is_creditable)
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{
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ssize_t ret;
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int urandom_fd;
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*is_creditable = false;
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ret = getrandom(seed, len, GRND_NONBLOCK);
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if (ret == (ssize_t)len) {
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*is_creditable = true;
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return 0;
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}
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if (ret == -1 && errno == ENOSYS) {
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struct pollfd random_fd = {
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.fd = open("/dev/random", O_RDONLY),
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.events = POLLIN
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};
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if (random_fd.fd < 0)
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return -errno;
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*is_creditable = poll(&random_fd, 1, 0) == 1;
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close(random_fd.fd);
|
||||
} else if (getrandom(seed, len, GRND_INSECURE) == (ssize_t)len)
|
||||
return 0;
|
||||
urandom_fd = open("/dev/urandom", O_RDONLY);
|
||||
if (urandom_fd < 0)
|
||||
return -errno;
|
||||
ret = read(urandom_fd, seed, len);
|
||||
if (ret == (ssize_t)len)
|
||||
ret = 0;
|
||||
else
|
||||
ret = -errno ? -errno : -EIO;
|
||||
close(urandom_fd);
|
||||
return ret;
|
||||
}
|
||||
|
||||
static int seed_rng(uint8_t *seed, size_t len, bool credit)
|
||||
{
|
||||
struct {
|
||||
int entropy_count;
|
||||
int buf_size;
|
||||
uint8_t buffer[MAX_SEED_LEN];
|
||||
} req = {
|
||||
.entropy_count = credit ? len * 8 : 0,
|
||||
.buf_size = len
|
||||
};
|
||||
int random_fd, ret;
|
||||
|
||||
if (len > sizeof(req.buffer))
|
||||
return -EFBIG;
|
||||
memcpy(req.buffer, seed, len);
|
||||
|
||||
random_fd = open("/dev/random", O_RDWR);
|
||||
if (random_fd < 0)
|
||||
return -errno;
|
||||
ret = ioctl(random_fd, RNDADDENTROPY, &req);
|
||||
if (ret)
|
||||
ret = -errno ? -errno : -EIO;
|
||||
close(random_fd);
|
||||
return ret;
|
||||
}
|
||||
|
||||
static int seed_from_file_if_exists(const char *filename, bool credit, struct blake2s_state *hash)
|
||||
{
|
||||
uint8_t seed[MAX_SEED_LEN];
|
||||
ssize_t seed_len;
|
||||
int fd, dfd, ret = 0;
|
||||
|
||||
fd = open(filename, O_RDONLY);
|
||||
if (fd < 0 && errno == ENOENT)
|
||||
return 0;
|
||||
else if (fd < 0) {
|
||||
ret = -errno;
|
||||
eerror("Unable to open seed file: %s", strerror(errno));
|
||||
return ret;
|
||||
}
|
||||
dfd = open(SEED_DIR, O_DIRECTORY | O_RDONLY);
|
||||
if (dfd < 0) {
|
||||
ret = -errno;
|
||||
close(fd);
|
||||
eerror("Unable to open seed directory: %s", strerror(errno));
|
||||
return ret;
|
||||
}
|
||||
seed_len = read(fd, seed, sizeof(seed));
|
||||
if (seed_len < 0) {
|
||||
ret = -errno;
|
||||
eerror("Unable to read seed file: %s", strerror(errno));
|
||||
}
|
||||
close(fd);
|
||||
if (ret) {
|
||||
close(dfd);
|
||||
return ret;
|
||||
}
|
||||
if ((unlink(filename) < 0 || fsync(dfd) < 0) && seed_len) {
|
||||
ret = -errno;
|
||||
eerror("Unable to remove seed after reading, so not seeding: %s", strerror(errno));
|
||||
}
|
||||
close(dfd);
|
||||
if (ret)
|
||||
return ret;
|
||||
if (!seed_len)
|
||||
return 0;
|
||||
|
||||
blake2s_update(hash, &seed_len, sizeof(seed_len));
|
||||
blake2s_update(hash, seed, seed_len);
|
||||
|
||||
einfo("Seeding %zd bits %s crediting", seed_len * 8, credit ? "and" : "without");
|
||||
ret = seed_rng(seed, seed_len, credit);
|
||||
if (ret < 0)
|
||||
eerror("Unable to seed: %s", strerror(-ret));
|
||||
return ret;
|
||||
}
|
||||
|
||||
static void populate_global_paths(void)
|
||||
{
|
||||
SEED_DIR = getenv("SEEDRNG_SEED_DIR");
|
||||
if (!SEED_DIR || !*SEED_DIR)
|
||||
SEED_DIR = "/var/lib/seedrng";
|
||||
LOCK_FILE = getenv("SEEDRNG_LOCK_FILE");
|
||||
if (!LOCK_FILE || !*LOCK_FILE)
|
||||
LOCK_FILE = "/var/run/seedrng.lock";
|
||||
xasprintf(&CREDITABLE_SEED, "%s/seed.credit", SEED_DIR);
|
||||
xasprintf(&NON_CREDITABLE_SEED, "%s/seed.no-credit", SEED_DIR);
|
||||
}
|
||||
|
||||
int main(int argc _unused, char *argv[] _unused)
|
||||
{
|
||||
static const char seedrng_prefix[] = "SeedRNG v1 Old+New Prefix";
|
||||
static const char seedrng_failure[] = "SeedRNG v1 No New Seed Failure";
|
||||
int ret, fd, lock, program_ret = 0;
|
||||
uint8_t new_seed[MAX_SEED_LEN];
|
||||
size_t new_seed_len;
|
||||
bool new_seed_creditable;
|
||||
struct timespec realtime = { 0 }, boottime = { 0 };
|
||||
struct blake2s_state hash;
|
||||
|
||||
umask(0077);
|
||||
if (getuid())
|
||||
eerrorx("This rc helper program requires root");
|
||||
|
||||
populate_global_paths();
|
||||
blake2s_init(&hash, BLAKE2S_HASH_LEN);
|
||||
blake2s_update(&hash, seedrng_prefix, strlen(seedrng_prefix));
|
||||
clock_gettime(CLOCK_REALTIME, &realtime);
|
||||
clock_gettime(CLOCK_BOOTTIME, &boottime);
|
||||
blake2s_update(&hash, &realtime, sizeof(realtime));
|
||||
blake2s_update(&hash, &boottime, sizeof(boottime));
|
||||
|
||||
if (mkdir(SEED_DIR, 0700) < 0 && errno != EEXIST)
|
||||
eerrorx("Unable to create \"%s\" directory: %s", SEED_DIR, strerror(errno));
|
||||
|
||||
lock = open(LOCK_FILE, O_WRONLY | O_CREAT, 0000);
|
||||
if (lock < 0 || flock(lock, LOCK_EX) < 0)
|
||||
eerrorx("Unable to open lock file: %s", strerror(errno));
|
||||
|
||||
ret = seed_from_file_if_exists(NON_CREDITABLE_SEED, false, &hash);
|
||||
if (ret < 0)
|
||||
program_ret |= 1 << 1;
|
||||
ret = seed_from_file_if_exists(CREDITABLE_SEED, !rc_yesno(getenv("SEEDRNG_SKIP_CREDIT")), &hash);
|
||||
if (ret < 0)
|
||||
program_ret |= 1 << 2;
|
||||
|
||||
new_seed_len = determine_optimal_seed_len();
|
||||
ret = read_new_seed(new_seed, new_seed_len, &new_seed_creditable);
|
||||
if (ret < 0) {
|
||||
eerror("Unable to read new seed: %s", strerror(-ret));
|
||||
new_seed_len = BLAKE2S_HASH_LEN;
|
||||
strncpy((char *)new_seed, seedrng_failure, new_seed_len);
|
||||
program_ret |= 1 << 3;
|
||||
}
|
||||
blake2s_update(&hash, &new_seed_len, sizeof(new_seed_len));
|
||||
blake2s_update(&hash, new_seed, new_seed_len);
|
||||
blake2s_final(&hash, new_seed + new_seed_len - BLAKE2S_HASH_LEN);
|
||||
|
||||
einfo("Saving %zu bits of %s seed for next boot", new_seed_len * 8, new_seed_creditable ? "creditable" : "non-creditable");
|
||||
fd = open(NON_CREDITABLE_SEED, O_WRONLY | O_CREAT | O_TRUNC, 0400);
|
||||
if (fd < 0) {
|
||||
eerror("Unable to open seed file for writing: %s", strerror(errno));
|
||||
program_ret |= 1 << 4;
|
||||
goto out;
|
||||
}
|
||||
if (write(fd, new_seed, new_seed_len) != (ssize_t)new_seed_len || fsync(fd) < 0) {
|
||||
eerror("Unable to write seed file: %s", strerror(errno));
|
||||
program_ret |= 1 << 5;
|
||||
goto out;
|
||||
}
|
||||
if (new_seed_creditable && rename(NON_CREDITABLE_SEED, CREDITABLE_SEED) < 0) {
|
||||
ewarn("Unable to make new seed creditable: %s", strerror(errno));
|
||||
program_ret |= 1 << 6;
|
||||
}
|
||||
out:
|
||||
close(fd);
|
||||
close(lock);
|
||||
return program_ret;
|
||||
}
|
||||
Loading…
Reference in New Issue