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- /*-
- * Copyright (c) 2017 The FreeBSD Foundation
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer
- * in this position and unchanged.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
- * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
- * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
- * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
- #include <sys/cdefs.h>
- __FBSDID("$FreeBSD$");
- #include <sys/types.h>
- #include <sys/param.h>
- #include <sys/kernel.h>
- #include <sys/libkern.h>
- #include <sys/linker.h>
- #include <sys/lock.h>
- #include <sys/malloc.h>
- #include <sys/mutex.h>
- #include <sys/random.h>
- #include <sys/smp.h>
- #include <sys/time.h>
- #include <machine/cpu.h>
- #include <crypto/chacha20/chacha.h>
- #include <crypto/sha2/sha256.h>
- #include <dev/random/randomdev.h>
- #ifdef RANDOM_FENESTRASX
- #include <dev/random/fenestrasX/fx_pub.h>
- #endif
- #define CHACHA20_RESEED_BYTES 65536
- #define CHACHA20_RESEED_SECONDS 300
- #define CHACHA20_KEYBYTES 32
- #define CHACHA20_BUFFER_SIZE 64
- CTASSERT(CHACHA20_KEYBYTES*8 >= CHACHA_MINKEYLEN);
- #ifndef RANDOM_FENESTRASX
- int arc4rand_iniseed_state = ARC4_ENTR_NONE;
- #endif
- MALLOC_DEFINE(M_CHACHA20RANDOM, "chacha20random", "chacha20random structures");
- struct chacha20_s {
- struct mtx mtx;
- int numbytes;
- time_t t_reseed;
- u_int8_t m_buffer[CHACHA20_BUFFER_SIZE];
- struct chacha_ctx ctx;
- #ifdef RANDOM_FENESTRASX
- uint64_t seed_version;
- #endif
- } __aligned(CACHE_LINE_SIZE);
- static struct chacha20_s *chacha20inst = NULL;
- #define CHACHA20_FOREACH(_chacha20) \
- for (_chacha20 = &chacha20inst[0]; \
- _chacha20 <= &chacha20inst[mp_maxid]; \
- _chacha20++)
- /*
- * Mix up the current context.
- */
- static void
- chacha20_randomstir(struct chacha20_s *chacha20)
- {
- struct timeval tv_now;
- u_int8_t key[CHACHA20_KEYBYTES];
- #ifdef RANDOM_FENESTRASX
- uint64_t seed_version;
- #else
- if (__predict_false(random_bypass_before_seeding && !is_random_seeded())) {
- SHA256_CTX ctx;
- uint64_t cc;
- uint32_t fver;
- if (!arc4random_bypassed_before_seeding) {
- arc4random_bypassed_before_seeding = true;
- if (!random_bypass_disable_warnings)
- printf("arc4random: WARNING: initial seeding "
- "bypassed the cryptographic random device "
- "because it was not yet seeded and the "
- "knob 'bypass_before_seeding' was "
- "enabled.\n");
- }
- /* Last ditch effort to inject something in a bad condition. */
- cc = get_cyclecount();
- SHA256_Init(&ctx);
- SHA256_Update(&ctx, key, sizeof(key));
- SHA256_Update(&ctx, &cc, sizeof(cc));
- fver = __FreeBSD_version;
- SHA256_Update(&ctx, &fver, sizeof(fver));
- _Static_assert(sizeof(key) == SHA256_DIGEST_LENGTH,
- "make sure 256 bits is still 256 bits");
- SHA256_Final(key, &ctx);
- } else {
- #endif
- #ifdef RANDOM_FENESTRASX
- read_random_key(key, CHACHA20_KEYBYTES, &seed_version);
- #else
- /*
- * If the loader(8) did not have an entropy stash from the
- * previous shutdown to load, then we will block. The answer is
- * to make sure there is an entropy stash at shutdown time.
- *
- * On the other hand, if the random_bypass_before_seeding knob
- * was set and we landed in this branch, we know this won't
- * block because we know the random device is seeded.
- */
- read_random(key, CHACHA20_KEYBYTES);
- }
- #endif
- getmicrouptime(&tv_now);
- mtx_lock(&chacha20->mtx);
- chacha_keysetup(&chacha20->ctx, key, CHACHA20_KEYBYTES*8);
- chacha_ivsetup(&chacha20->ctx, (u_char *)&tv_now.tv_sec, (u_char *)&tv_now.tv_usec);
- /* Reset for next reseed cycle. */
- chacha20->t_reseed = tv_now.tv_sec + CHACHA20_RESEED_SECONDS;
- chacha20->numbytes = 0;
- #ifdef RANDOM_FENESTRASX
- chacha20->seed_version = seed_version;
- #endif
- mtx_unlock(&chacha20->mtx);
- }
- /*
- * Initialize the contexts.
- */
- static void
- chacha20_init(void)
- {
- struct chacha20_s *chacha20;
- chacha20inst = malloc((mp_maxid + 1) * sizeof(struct chacha20_s),
- M_CHACHA20RANDOM, M_NOWAIT | M_ZERO);
- KASSERT(chacha20inst != NULL, ("chacha20_init: memory allocation error"));
- CHACHA20_FOREACH(chacha20) {
- mtx_init(&chacha20->mtx, "chacha20_mtx", NULL, MTX_DEF);
- chacha20->t_reseed = -1;
- chacha20->numbytes = 0;
- explicit_bzero(chacha20->m_buffer, CHACHA20_BUFFER_SIZE);
- explicit_bzero(&chacha20->ctx, sizeof(chacha20->ctx));
- }
- }
- SYSINIT(chacha20, SI_SUB_LOCK, SI_ORDER_ANY, chacha20_init, NULL);
- static void
- chacha20_uninit(void)
- {
- struct chacha20_s *chacha20;
- CHACHA20_FOREACH(chacha20)
- mtx_destroy(&chacha20->mtx);
- free(chacha20inst, M_CHACHA20RANDOM);
- }
- SYSUNINIT(chacha20, SI_SUB_LOCK, SI_ORDER_ANY, chacha20_uninit, NULL);
- /*
- * MPSAFE
- */
- void
- arc4rand(void *ptr, u_int len, int reseed)
- {
- struct chacha20_s *chacha20;
- struct timeval tv;
- u_int length;
- u_int8_t *p;
- #ifdef RANDOM_FENESTRASX
- if (__predict_false(reseed))
- #else
- if (__predict_false(reseed ||
- (arc4rand_iniseed_state == ARC4_ENTR_HAVE &&
- atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_HAVE, ARC4_ENTR_SEED))))
- #endif
- CHACHA20_FOREACH(chacha20)
- chacha20_randomstir(chacha20);
- getmicrouptime(&tv);
- chacha20 = &chacha20inst[curcpu];
- /* We may get unlucky and be migrated off this CPU, but that is expected to be infrequent */
- if ((chacha20->numbytes > CHACHA20_RESEED_BYTES) || (tv.tv_sec > chacha20->t_reseed))
- chacha20_randomstir(chacha20);
- mtx_lock(&chacha20->mtx);
- #ifdef RANDOM_FENESTRASX
- if (__predict_false(
- atomic_load_acq_64(&fxrng_root_generation) != chacha20->seed_version
- )) {
- mtx_unlock(&chacha20->mtx);
- chacha20_randomstir(chacha20);
- mtx_lock(&chacha20->mtx);
- }
- #endif
- p = ptr;
- while (len) {
- length = MIN(CHACHA20_BUFFER_SIZE, len);
- chacha_encrypt_bytes(&chacha20->ctx, chacha20->m_buffer, p, length);
- p += length;
- len -= length;
- chacha20->numbytes += length;
- if (chacha20->numbytes > CHACHA20_RESEED_BYTES) {
- mtx_unlock(&chacha20->mtx);
- chacha20_randomstir(chacha20);
- mtx_lock(&chacha20->mtx);
- }
- }
- mtx_unlock(&chacha20->mtx);
- }
- uint32_t
- arc4random(void)
- {
- uint32_t ret;
- arc4rand(&ret, sizeof(ret), 0);
- return ret;
- }
- void
- arc4random_buf(void *ptr, size_t len)
- {
- arc4rand(ptr, len, 0);
- }
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