/*- * 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 __FBSDID("$FreeBSD$"); #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #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); int arc4rand_iniseed_state = ARC4_ENTR_NONE; 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; } __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]; 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 { /* * 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); } 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; 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; if (reseed || atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_HAVE, ARC4_ENTR_SEED)) CHACHA20_FOREACH(chacha20) chacha20_randomstir(chacha20); chacha20 = &chacha20inst[curcpu]; getmicrouptime(&tv); /* 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); 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); }