5a37560e44
No functional change. Reviewed by: imp, emaste Differential Revision: https://reviews.freebsd.org/D33637
262 lines
7.2 KiB
C
262 lines
7.2 KiB
C
/*-
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* Copyright (c) 2017 The FreeBSD Foundation
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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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* in this position and unchanged.
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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 ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/types.h>
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/libkern.h>
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#include <sys/linker.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/msan.h>
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#include <sys/mutex.h>
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#include <sys/random.h>
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#include <sys/smp.h>
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#include <sys/time.h>
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#include <machine/cpu.h>
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#include <crypto/chacha20/chacha.h>
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#include <crypto/sha2/sha256.h>
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#include <dev/random/randomdev.h>
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#ifdef RANDOM_FENESTRASX
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#include <dev/random/fenestrasX/fx_pub.h>
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#endif
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#define CHACHA20_RESEED_BYTES 65536
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#define CHACHA20_RESEED_SECONDS 300
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#define CHACHA20_KEYBYTES 32
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#define CHACHA20_BUFFER_SIZE 64
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CTASSERT(CHACHA20_KEYBYTES*8 >= CHACHA_MINKEYLEN);
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#ifndef RANDOM_FENESTRASX
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int arc4rand_iniseed_state = ARC4_ENTR_NONE;
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#endif
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MALLOC_DEFINE(M_CHACHA20RANDOM, "chacha20random", "chacha20random structures");
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struct chacha20_s {
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struct mtx mtx;
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int numbytes;
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time_t t_reseed;
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uint8_t m_buffer[CHACHA20_BUFFER_SIZE];
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struct chacha_ctx ctx;
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#ifdef RANDOM_FENESTRASX
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uint64_t seed_version;
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#endif
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} __aligned(CACHE_LINE_SIZE);
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static struct chacha20_s *chacha20inst = NULL;
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#define CHACHA20_FOREACH(_chacha20) \
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for (_chacha20 = &chacha20inst[0]; \
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_chacha20 <= &chacha20inst[mp_maxid]; \
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_chacha20++)
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/*
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* Mix up the current context.
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*/
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static void
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chacha20_randomstir(struct chacha20_s *chacha20)
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{
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struct timeval tv_now;
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uint8_t key[CHACHA20_KEYBYTES];
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#ifdef RANDOM_FENESTRASX
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uint64_t seed_version;
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#else
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if (__predict_false(random_bypass_before_seeding && !is_random_seeded())) {
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SHA256_CTX ctx;
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uint64_t cc;
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uint32_t fver;
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if (!arc4random_bypassed_before_seeding) {
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arc4random_bypassed_before_seeding = true;
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if (!random_bypass_disable_warnings)
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printf("arc4random: WARNING: initial seeding "
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"bypassed the cryptographic random device "
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"because it was not yet seeded and the "
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"knob 'bypass_before_seeding' was "
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"enabled.\n");
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}
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/*
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* "key" is intentionally left uninitialized here, so with KMSAN
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* enabled the arc4random() return value may be marked
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* uninitialized, leading to spurious reports. Lie to KMSAN to
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* avoid this situation.
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*/
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kmsan_mark(key, sizeof(key), KMSAN_STATE_INITED);
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/* Last ditch effort to inject something in a bad condition. */
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cc = get_cyclecount();
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SHA256_Init(&ctx);
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SHA256_Update(&ctx, key, sizeof(key));
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SHA256_Update(&ctx, &cc, sizeof(cc));
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fver = __FreeBSD_version;
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SHA256_Update(&ctx, &fver, sizeof(fver));
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_Static_assert(sizeof(key) == SHA256_DIGEST_LENGTH,
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"make sure 256 bits is still 256 bits");
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SHA256_Final(key, &ctx);
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} else {
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#endif
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#ifdef RANDOM_FENESTRASX
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read_random_key(key, CHACHA20_KEYBYTES, &seed_version);
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#else
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/*
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* If the loader(8) did not have an entropy stash from the
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* previous shutdown to load, then we will block. The answer is
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* to make sure there is an entropy stash at shutdown time.
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*
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* On the other hand, if the random_bypass_before_seeding knob
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* was set and we landed in this branch, we know this won't
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* block because we know the random device is seeded.
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*/
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read_random(key, CHACHA20_KEYBYTES);
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}
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#endif
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getmicrouptime(&tv_now);
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mtx_lock(&chacha20->mtx);
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chacha_keysetup(&chacha20->ctx, key, CHACHA20_KEYBYTES*8);
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chacha_ivsetup(&chacha20->ctx, (u_char *)&tv_now.tv_sec, (u_char *)&tv_now.tv_usec);
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/* Reset for next reseed cycle. */
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chacha20->t_reseed = tv_now.tv_sec + CHACHA20_RESEED_SECONDS;
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chacha20->numbytes = 0;
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#ifdef RANDOM_FENESTRASX
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chacha20->seed_version = seed_version;
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#endif
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mtx_unlock(&chacha20->mtx);
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}
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/*
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* Initialize the contexts.
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*/
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static void
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chacha20_init(void)
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{
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struct chacha20_s *chacha20;
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chacha20inst = malloc((mp_maxid + 1) * sizeof(struct chacha20_s),
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M_CHACHA20RANDOM, M_NOWAIT | M_ZERO);
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KASSERT(chacha20inst != NULL, ("chacha20_init: memory allocation error"));
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CHACHA20_FOREACH(chacha20) {
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mtx_init(&chacha20->mtx, "chacha20_mtx", NULL, MTX_DEF);
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chacha20->t_reseed = -1;
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chacha20->numbytes = 0;
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explicit_bzero(chacha20->m_buffer, CHACHA20_BUFFER_SIZE);
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explicit_bzero(&chacha20->ctx, sizeof(chacha20->ctx));
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}
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}
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SYSINIT(chacha20, SI_SUB_LOCK, SI_ORDER_ANY, chacha20_init, NULL);
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static void
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chacha20_uninit(void)
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{
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struct chacha20_s *chacha20;
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CHACHA20_FOREACH(chacha20)
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mtx_destroy(&chacha20->mtx);
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free(chacha20inst, M_CHACHA20RANDOM);
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}
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SYSUNINIT(chacha20, SI_SUB_LOCK, SI_ORDER_ANY, chacha20_uninit, NULL);
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/*
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* MPSAFE
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*/
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void
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arc4rand(void *ptr, u_int len, int reseed)
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{
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struct chacha20_s *chacha20;
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struct timeval tv;
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u_int length;
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uint8_t *p;
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#ifdef RANDOM_FENESTRASX
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if (__predict_false(reseed))
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#else
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if (__predict_false(reseed ||
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(arc4rand_iniseed_state == ARC4_ENTR_HAVE &&
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atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_HAVE, ARC4_ENTR_SEED))))
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#endif
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CHACHA20_FOREACH(chacha20)
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chacha20_randomstir(chacha20);
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getmicrouptime(&tv);
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chacha20 = &chacha20inst[curcpu];
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/* We may get unlucky and be migrated off this CPU, but that is expected to be infrequent */
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if ((chacha20->numbytes > CHACHA20_RESEED_BYTES) || (tv.tv_sec > chacha20->t_reseed))
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chacha20_randomstir(chacha20);
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mtx_lock(&chacha20->mtx);
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#ifdef RANDOM_FENESTRASX
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if (__predict_false(
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atomic_load_acq_64(&fxrng_root_generation) != chacha20->seed_version
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)) {
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mtx_unlock(&chacha20->mtx);
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chacha20_randomstir(chacha20);
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mtx_lock(&chacha20->mtx);
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}
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#endif
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p = ptr;
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while (len) {
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length = MIN(CHACHA20_BUFFER_SIZE, len);
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chacha_encrypt_bytes(&chacha20->ctx, chacha20->m_buffer, p, length);
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p += length;
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len -= length;
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chacha20->numbytes += length;
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if (chacha20->numbytes > CHACHA20_RESEED_BYTES) {
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mtx_unlock(&chacha20->mtx);
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chacha20_randomstir(chacha20);
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mtx_lock(&chacha20->mtx);
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}
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}
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mtx_unlock(&chacha20->mtx);
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}
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uint32_t
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arc4random(void)
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{
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uint32_t ret;
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arc4rand(&ret, sizeof(ret), 0);
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return ret;
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}
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void
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arc4random_buf(void *ptr, size_t len)
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{
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arc4rand(ptr, len, 0);
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}
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