1 /*- 2 * Copyright (c) 2017 The FreeBSD Foundation 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer 10 * in this position and unchanged. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 */ 27 28 #include <sys/cdefs.h> 29 __FBSDID("$FreeBSD$"); 30 31 #include <sys/types.h> 32 #include <sys/param.h> 33 #include <sys/kernel.h> 34 #include <sys/libkern.h> 35 #include <sys/linker.h> 36 #include <sys/lock.h> 37 #include <sys/malloc.h> 38 #include <sys/mutex.h> 39 #include <sys/random.h> 40 #include <sys/smp.h> 41 #include <sys/time.h> 42 43 #include <machine/cpu.h> 44 45 #include <crypto/chacha20/chacha.h> 46 #include <crypto/sha2/sha256.h> 47 #include <dev/random/randomdev.h> 48 #ifdef RANDOM_FENESTRASX 49 #include <dev/random/fenestrasX/fx_pub.h> 50 #endif 51 52 #define CHACHA20_RESEED_BYTES 65536 53 #define CHACHA20_RESEED_SECONDS 300 54 #define CHACHA20_KEYBYTES 32 55 #define CHACHA20_BUFFER_SIZE 64 56 57 CTASSERT(CHACHA20_KEYBYTES*8 >= CHACHA_MINKEYLEN); 58 59 #ifndef RANDOM_FENESTRASX 60 int arc4rand_iniseed_state = ARC4_ENTR_NONE; 61 #endif 62 63 MALLOC_DEFINE(M_CHACHA20RANDOM, "chacha20random", "chacha20random structures"); 64 65 struct chacha20_s { 66 struct mtx mtx; 67 int numbytes; 68 time_t t_reseed; 69 u_int8_t m_buffer[CHACHA20_BUFFER_SIZE]; 70 struct chacha_ctx ctx; 71 #ifdef RANDOM_FENESTRASX 72 uint64_t seed_version; 73 #endif 74 } __aligned(CACHE_LINE_SIZE); 75 76 static struct chacha20_s *chacha20inst = NULL; 77 78 #define CHACHA20_FOREACH(_chacha20) \ 79 for (_chacha20 = &chacha20inst[0]; \ 80 _chacha20 <= &chacha20inst[mp_maxid]; \ 81 _chacha20++) 82 83 /* 84 * Mix up the current context. 85 */ 86 static void 87 chacha20_randomstir(struct chacha20_s *chacha20) 88 { 89 struct timeval tv_now; 90 u_int8_t key[CHACHA20_KEYBYTES]; 91 #ifdef RANDOM_FENESTRASX 92 uint64_t seed_version; 93 94 #else 95 if (__predict_false(random_bypass_before_seeding && !is_random_seeded())) { 96 SHA256_CTX ctx; 97 uint64_t cc; 98 uint32_t fver; 99 100 if (!arc4random_bypassed_before_seeding) { 101 arc4random_bypassed_before_seeding = true; 102 if (!random_bypass_disable_warnings) 103 printf("arc4random: WARNING: initial seeding " 104 "bypassed the cryptographic random device " 105 "because it was not yet seeded and the " 106 "knob 'bypass_before_seeding' was " 107 "enabled.\n"); 108 } 109 110 /* Last ditch effort to inject something in a bad condition. */ 111 cc = get_cyclecount(); 112 SHA256_Init(&ctx); 113 SHA256_Update(&ctx, key, sizeof(key)); 114 SHA256_Update(&ctx, &cc, sizeof(cc)); 115 fver = __FreeBSD_version; 116 SHA256_Update(&ctx, &fver, sizeof(fver)); 117 _Static_assert(sizeof(key) == SHA256_DIGEST_LENGTH, 118 "make sure 256 bits is still 256 bits"); 119 SHA256_Final(key, &ctx); 120 } else { 121 #endif 122 #ifdef RANDOM_FENESTRASX 123 read_random_key(key, CHACHA20_KEYBYTES, &seed_version); 124 #else 125 /* 126 * If the loader(8) did not have an entropy stash from the 127 * previous shutdown to load, then we will block. The answer is 128 * to make sure there is an entropy stash at shutdown time. 129 * 130 * On the other hand, if the random_bypass_before_seeding knob 131 * was set and we landed in this branch, we know this won't 132 * block because we know the random device is seeded. 133 */ 134 read_random(key, CHACHA20_KEYBYTES); 135 } 136 #endif 137 getmicrouptime(&tv_now); 138 mtx_lock(&chacha20->mtx); 139 chacha_keysetup(&chacha20->ctx, key, CHACHA20_KEYBYTES*8); 140 chacha_ivsetup(&chacha20->ctx, (u_char *)&tv_now.tv_sec, (u_char *)&tv_now.tv_usec); 141 /* Reset for next reseed cycle. */ 142 chacha20->t_reseed = tv_now.tv_sec + CHACHA20_RESEED_SECONDS; 143 chacha20->numbytes = 0; 144 #ifdef RANDOM_FENESTRASX 145 chacha20->seed_version = seed_version; 146 #endif 147 mtx_unlock(&chacha20->mtx); 148 } 149 150 /* 151 * Initialize the contexts. 152 */ 153 static void 154 chacha20_init(void) 155 { 156 struct chacha20_s *chacha20; 157 158 chacha20inst = malloc((mp_maxid + 1) * sizeof(struct chacha20_s), 159 M_CHACHA20RANDOM, M_NOWAIT | M_ZERO); 160 KASSERT(chacha20inst != NULL, ("chacha20_init: memory allocation error")); 161 162 CHACHA20_FOREACH(chacha20) { 163 mtx_init(&chacha20->mtx, "chacha20_mtx", NULL, MTX_DEF); 164 chacha20->t_reseed = -1; 165 chacha20->numbytes = 0; 166 explicit_bzero(chacha20->m_buffer, CHACHA20_BUFFER_SIZE); 167 explicit_bzero(&chacha20->ctx, sizeof(chacha20->ctx)); 168 } 169 } 170 SYSINIT(chacha20, SI_SUB_LOCK, SI_ORDER_ANY, chacha20_init, NULL); 171 172 173 static void 174 chacha20_uninit(void) 175 { 176 struct chacha20_s *chacha20; 177 178 CHACHA20_FOREACH(chacha20) 179 mtx_destroy(&chacha20->mtx); 180 free(chacha20inst, M_CHACHA20RANDOM); 181 } 182 SYSUNINIT(chacha20, SI_SUB_LOCK, SI_ORDER_ANY, chacha20_uninit, NULL); 183 184 185 /* 186 * MPSAFE 187 */ 188 void 189 arc4rand(void *ptr, u_int len, int reseed) 190 { 191 struct chacha20_s *chacha20; 192 struct timeval tv; 193 u_int length; 194 u_int8_t *p; 195 196 #ifdef RANDOM_FENESTRASX 197 if (__predict_false(reseed)) 198 #else 199 if (__predict_false(reseed || 200 (arc4rand_iniseed_state == ARC4_ENTR_HAVE && 201 atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_HAVE, ARC4_ENTR_SEED)))) 202 #endif 203 CHACHA20_FOREACH(chacha20) 204 chacha20_randomstir(chacha20); 205 206 getmicrouptime(&tv); 207 chacha20 = &chacha20inst[curcpu]; 208 /* We may get unlucky and be migrated off this CPU, but that is expected to be infrequent */ 209 if ((chacha20->numbytes > CHACHA20_RESEED_BYTES) || (tv.tv_sec > chacha20->t_reseed)) 210 chacha20_randomstir(chacha20); 211 212 mtx_lock(&chacha20->mtx); 213 #ifdef RANDOM_FENESTRASX 214 if (__predict_false( 215 atomic_load_acq_64(&fxrng_root_generation) != chacha20->seed_version 216 )) { 217 mtx_unlock(&chacha20->mtx); 218 chacha20_randomstir(chacha20); 219 mtx_lock(&chacha20->mtx); 220 } 221 #endif 222 223 p = ptr; 224 while (len) { 225 length = MIN(CHACHA20_BUFFER_SIZE, len); 226 chacha_encrypt_bytes(&chacha20->ctx, chacha20->m_buffer, p, length); 227 p += length; 228 len -= length; 229 chacha20->numbytes += length; 230 if (chacha20->numbytes > CHACHA20_RESEED_BYTES) { 231 mtx_unlock(&chacha20->mtx); 232 chacha20_randomstir(chacha20); 233 mtx_lock(&chacha20->mtx); 234 } 235 } 236 mtx_unlock(&chacha20->mtx); 237 } 238 239 uint32_t 240 arc4random(void) 241 { 242 uint32_t ret; 243 244 arc4rand(&ret, sizeof(ret), 0); 245 return ret; 246 } 247 248 void 249 arc4random_buf(void *ptr, size_t len) 250 { 251 252 arc4rand(ptr, len, 0); 253 } 254