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