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/msan.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 /* 111 * "key" is intentionally left uninitialized here, so with KMSAN 112 * enabled the arc4random() return value may be marked 113 * uninitialized, leading to spurious reports. Lie to KMSAN to 114 * avoid this situation. 115 */ 116 kmsan_mark(key, sizeof(key), KMSAN_STATE_INITED); 117 118 /* Last ditch effort to inject something in a bad condition. */ 119 cc = get_cyclecount(); 120 SHA256_Init(&ctx); 121 SHA256_Update(&ctx, key, sizeof(key)); 122 SHA256_Update(&ctx, &cc, sizeof(cc)); 123 fver = __FreeBSD_version; 124 SHA256_Update(&ctx, &fver, sizeof(fver)); 125 _Static_assert(sizeof(key) == SHA256_DIGEST_LENGTH, 126 "make sure 256 bits is still 256 bits"); 127 SHA256_Final(key, &ctx); 128 } else { 129 #endif 130 #ifdef RANDOM_FENESTRASX 131 read_random_key(key, CHACHA20_KEYBYTES, &seed_version); 132 #else 133 /* 134 * If the loader(8) did not have an entropy stash from the 135 * previous shutdown to load, then we will block. The answer is 136 * to make sure there is an entropy stash at shutdown time. 137 * 138 * On the other hand, if the random_bypass_before_seeding knob 139 * was set and we landed in this branch, we know this won't 140 * block because we know the random device is seeded. 141 */ 142 read_random(key, CHACHA20_KEYBYTES); 143 } 144 #endif 145 getmicrouptime(&tv_now); 146 mtx_lock(&chacha20->mtx); 147 chacha_keysetup(&chacha20->ctx, key, CHACHA20_KEYBYTES*8); 148 chacha_ivsetup(&chacha20->ctx, (u_char *)&tv_now.tv_sec, (u_char *)&tv_now.tv_usec); 149 /* Reset for next reseed cycle. */ 150 chacha20->t_reseed = tv_now.tv_sec + CHACHA20_RESEED_SECONDS; 151 chacha20->numbytes = 0; 152 #ifdef RANDOM_FENESTRASX 153 chacha20->seed_version = seed_version; 154 #endif 155 mtx_unlock(&chacha20->mtx); 156 } 157 158 /* 159 * Initialize the contexts. 160 */ 161 static void 162 chacha20_init(void) 163 { 164 struct chacha20_s *chacha20; 165 166 chacha20inst = malloc((mp_maxid + 1) * sizeof(struct chacha20_s), 167 M_CHACHA20RANDOM, M_NOWAIT | M_ZERO); 168 KASSERT(chacha20inst != NULL, ("chacha20_init: memory allocation error")); 169 170 CHACHA20_FOREACH(chacha20) { 171 mtx_init(&chacha20->mtx, "chacha20_mtx", NULL, MTX_DEF); 172 chacha20->t_reseed = -1; 173 chacha20->numbytes = 0; 174 explicit_bzero(chacha20->m_buffer, CHACHA20_BUFFER_SIZE); 175 explicit_bzero(&chacha20->ctx, sizeof(chacha20->ctx)); 176 } 177 } 178 SYSINIT(chacha20, SI_SUB_LOCK, SI_ORDER_ANY, chacha20_init, NULL); 179 180 181 static void 182 chacha20_uninit(void) 183 { 184 struct chacha20_s *chacha20; 185 186 CHACHA20_FOREACH(chacha20) 187 mtx_destroy(&chacha20->mtx); 188 free(chacha20inst, M_CHACHA20RANDOM); 189 } 190 SYSUNINIT(chacha20, SI_SUB_LOCK, SI_ORDER_ANY, chacha20_uninit, NULL); 191 192 193 /* 194 * MPSAFE 195 */ 196 void 197 arc4rand(void *ptr, u_int len, int reseed) 198 { 199 struct chacha20_s *chacha20; 200 struct timeval tv; 201 u_int length; 202 u_int8_t *p; 203 204 #ifdef RANDOM_FENESTRASX 205 if (__predict_false(reseed)) 206 #else 207 if (__predict_false(reseed || 208 (arc4rand_iniseed_state == ARC4_ENTR_HAVE && 209 atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_HAVE, ARC4_ENTR_SEED)))) 210 #endif 211 CHACHA20_FOREACH(chacha20) 212 chacha20_randomstir(chacha20); 213 214 getmicrouptime(&tv); 215 chacha20 = &chacha20inst[curcpu]; 216 /* We may get unlucky and be migrated off this CPU, but that is expected to be infrequent */ 217 if ((chacha20->numbytes > CHACHA20_RESEED_BYTES) || (tv.tv_sec > chacha20->t_reseed)) 218 chacha20_randomstir(chacha20); 219 220 mtx_lock(&chacha20->mtx); 221 #ifdef RANDOM_FENESTRASX 222 if (__predict_false( 223 atomic_load_acq_64(&fxrng_root_generation) != chacha20->seed_version 224 )) { 225 mtx_unlock(&chacha20->mtx); 226 chacha20_randomstir(chacha20); 227 mtx_lock(&chacha20->mtx); 228 } 229 #endif 230 231 p = ptr; 232 while (len) { 233 length = MIN(CHACHA20_BUFFER_SIZE, len); 234 chacha_encrypt_bytes(&chacha20->ctx, chacha20->m_buffer, p, length); 235 p += length; 236 len -= length; 237 chacha20->numbytes += length; 238 if (chacha20->numbytes > CHACHA20_RESEED_BYTES) { 239 mtx_unlock(&chacha20->mtx); 240 chacha20_randomstir(chacha20); 241 mtx_lock(&chacha20->mtx); 242 } 243 } 244 mtx_unlock(&chacha20->mtx); 245 } 246 247 uint32_t 248 arc4random(void) 249 { 250 uint32_t ret; 251 252 arc4rand(&ret, sizeof(ret), 0); 253 return ret; 254 } 255 256 void 257 arc4random_buf(void *ptr, size_t len) 258 { 259 260 arc4rand(ptr, len, 0); 261 } 262