1 /*- 2 * Copyright (c) 2017 W. Dean Freeman 3 * Copyright (c) 2013-2015 Mark R V Murray 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer 11 * in this position and unchanged. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * 27 */ 28 29 /* 30 * This implementation of Fortuna is based on the descriptions found in 31 * ISBN 978-0-470-47424-2 "Cryptography Engineering" by Ferguson, Schneier 32 * and Kohno ("FS&K"). 33 */ 34 35 #include <sys/cdefs.h> 36 __FBSDID("$FreeBSD$"); 37 38 #include <sys/limits.h> 39 40 #ifdef _KERNEL 41 #include <sys/param.h> 42 #include <sys/kernel.h> 43 #include <sys/lock.h> 44 #include <sys/malloc.h> 45 #include <sys/mutex.h> 46 #include <sys/random.h> 47 #include <sys/sdt.h> 48 #include <sys/sysctl.h> 49 #include <sys/systm.h> 50 51 #include <machine/cpu.h> 52 53 #include <crypto/rijndael/rijndael-api-fst.h> 54 #include <crypto/sha2/sha256.h> 55 56 #include <dev/random/hash.h> 57 #include <dev/random/randomdev.h> 58 #include <dev/random/random_harvestq.h> 59 #include <dev/random/uint128.h> 60 #include <dev/random/fortuna.h> 61 #else /* !_KERNEL */ 62 #include <inttypes.h> 63 #include <stdbool.h> 64 #include <stdio.h> 65 #include <stdlib.h> 66 #include <string.h> 67 #include <threads.h> 68 69 #include "unit_test.h" 70 71 #include <crypto/rijndael/rijndael-api-fst.h> 72 #include <crypto/sha2/sha256.h> 73 74 #include <dev/random/hash.h> 75 #include <dev/random/randomdev.h> 76 #include <dev/random/uint128.h> 77 #include <dev/random/fortuna.h> 78 #endif /* _KERNEL */ 79 80 /* Defined in FS&K */ 81 #define RANDOM_FORTUNA_NPOOLS 32 /* The number of accumulation pools */ 82 #define RANDOM_FORTUNA_DEFPOOLSIZE 64 /* The default pool size/length for a (re)seed */ 83 #define RANDOM_FORTUNA_MAX_READ (1 << 20) /* Max bytes in a single read */ 84 85 /* 86 * The allowable range of RANDOM_FORTUNA_DEFPOOLSIZE. The default value is above. 87 * Making RANDOM_FORTUNA_DEFPOOLSIZE too large will mean a long time between reseeds, 88 * and too small may compromise initial security but get faster reseeds. 89 */ 90 #define RANDOM_FORTUNA_MINPOOLSIZE 16 91 #define RANDOM_FORTUNA_MAXPOOLSIZE INT_MAX 92 CTASSERT(RANDOM_FORTUNA_MINPOOLSIZE <= RANDOM_FORTUNA_DEFPOOLSIZE); 93 CTASSERT(RANDOM_FORTUNA_DEFPOOLSIZE <= RANDOM_FORTUNA_MAXPOOLSIZE); 94 95 /* This algorithm (and code) presumes that RANDOM_KEYSIZE is twice as large as RANDOM_BLOCKSIZE */ 96 CTASSERT(RANDOM_BLOCKSIZE == sizeof(uint128_t)); 97 CTASSERT(RANDOM_KEYSIZE == 2*RANDOM_BLOCKSIZE); 98 99 /* Probes for dtrace(1) */ 100 SDT_PROVIDER_DECLARE(random); 101 SDT_PROVIDER_DEFINE(random); 102 SDT_PROBE_DEFINE2(random, fortuna, event_processor, debug, "u_int", "struct fs_pool *"); 103 104 /* 105 * This is the beastie that needs protecting. It contains all of the 106 * state that we are excited about. Exactly one is instantiated. 107 */ 108 static struct fortuna_state { 109 struct fs_pool { /* P_i */ 110 u_int fsp_length; /* Only the first one is used by Fortuna */ 111 struct randomdev_hash fsp_hash; 112 } fs_pool[RANDOM_FORTUNA_NPOOLS]; 113 u_int fs_reseedcount; /* ReseedCnt */ 114 uint128_t fs_counter; /* C */ 115 struct randomdev_key fs_key; /* K */ 116 u_int fs_minpoolsize; /* Extras */ 117 /* Extras for the OS */ 118 #ifdef _KERNEL 119 /* For use when 'pacing' the reseeds */ 120 sbintime_t fs_lasttime; 121 #endif 122 /* Reseed lock */ 123 mtx_t fs_mtx; 124 } fortuna_state; 125 126 #ifdef _KERNEL 127 static struct sysctl_ctx_list random_clist; 128 RANDOM_CHECK_UINT(fs_minpoolsize, RANDOM_FORTUNA_MINPOOLSIZE, RANDOM_FORTUNA_MAXPOOLSIZE); 129 #else 130 static uint8_t zero_region[RANDOM_ZERO_BLOCKSIZE]; 131 #endif 132 133 static void random_fortuna_pre_read(void); 134 static void random_fortuna_read(uint8_t *, u_int); 135 static bool random_fortuna_seeded(void); 136 static void random_fortuna_process_event(struct harvest_event *); 137 static void random_fortuna_init_alg(void *); 138 static void random_fortuna_deinit_alg(void *); 139 140 static void random_fortuna_reseed_internal(uint32_t *entropy_data, u_int blockcount); 141 142 struct random_algorithm random_alg_context = { 143 .ra_ident = "Fortuna", 144 .ra_init_alg = random_fortuna_init_alg, 145 .ra_deinit_alg = random_fortuna_deinit_alg, 146 .ra_pre_read = random_fortuna_pre_read, 147 .ra_read = random_fortuna_read, 148 .ra_seeded = random_fortuna_seeded, 149 .ra_event_processor = random_fortuna_process_event, 150 .ra_poolcount = RANDOM_FORTUNA_NPOOLS, 151 }; 152 153 /* ARGSUSED */ 154 static void 155 random_fortuna_init_alg(void *unused __unused) 156 { 157 int i; 158 #ifdef _KERNEL 159 struct sysctl_oid *random_fortuna_o; 160 #endif 161 162 RANDOM_RESEED_INIT_LOCK(); 163 /* 164 * Fortuna parameters. Do not adjust these unless you have 165 * have a very good clue about what they do! 166 */ 167 fortuna_state.fs_minpoolsize = RANDOM_FORTUNA_DEFPOOLSIZE; 168 #ifdef _KERNEL 169 fortuna_state.fs_lasttime = 0; 170 random_fortuna_o = SYSCTL_ADD_NODE(&random_clist, 171 SYSCTL_STATIC_CHILDREN(_kern_random), 172 OID_AUTO, "fortuna", CTLFLAG_RW, 0, 173 "Fortuna Parameters"); 174 SYSCTL_ADD_PROC(&random_clist, 175 SYSCTL_CHILDREN(random_fortuna_o), OID_AUTO, 176 "minpoolsize", CTLTYPE_UINT | CTLFLAG_RWTUN, 177 &fortuna_state.fs_minpoolsize, RANDOM_FORTUNA_DEFPOOLSIZE, 178 random_check_uint_fs_minpoolsize, "IU", 179 "Minimum pool size necessary to cause a reseed"); 180 KASSERT(fortuna_state.fs_minpoolsize > 0, ("random: Fortuna threshold must be > 0 at startup")); 181 #endif 182 183 /*- 184 * FS&K - InitializePRNG() 185 * - P_i = \epsilon 186 * - ReseedCNT = 0 187 */ 188 for (i = 0; i < RANDOM_FORTUNA_NPOOLS; i++) { 189 randomdev_hash_init(&fortuna_state.fs_pool[i].fsp_hash); 190 fortuna_state.fs_pool[i].fsp_length = 0; 191 } 192 fortuna_state.fs_reseedcount = 0; 193 /*- 194 * FS&K - InitializeGenerator() 195 * - C = 0 196 * - K = 0 197 */ 198 fortuna_state.fs_counter = UINT128_ZERO; 199 explicit_bzero(&fortuna_state.fs_key, sizeof(fortuna_state.fs_key)); 200 } 201 202 /* ARGSUSED */ 203 static void 204 random_fortuna_deinit_alg(void *unused __unused) 205 { 206 207 RANDOM_RESEED_DEINIT_LOCK(); 208 explicit_bzero(&fortuna_state, sizeof(fortuna_state)); 209 #ifdef _KERNEL 210 sysctl_ctx_free(&random_clist); 211 #endif 212 } 213 214 /*- 215 * FS&K - AddRandomEvent() 216 * Process a single stochastic event off the harvest queue 217 */ 218 static void 219 random_fortuna_process_event(struct harvest_event *event) 220 { 221 u_int pl; 222 223 RANDOM_RESEED_LOCK(); 224 /*- 225 * FS&K - P_i = P_i|<harvested stuff> 226 * Accumulate the event into the appropriate pool 227 * where each event carries the destination information. 228 * 229 * The hash_init() and hash_finish() calls are done in 230 * random_fortuna_pre_read(). 231 * 232 * We must be locked against pool state modification which can happen 233 * during accumulation/reseeding and reading/regating. 234 */ 235 pl = event->he_destination % RANDOM_FORTUNA_NPOOLS; 236 /* 237 * We ignore low entropy static/counter fields towards the end of the 238 * he_event structure in order to increase measurable entropy when 239 * conducting SP800-90B entropy analysis measurements of seed material 240 * fed into PRNG. 241 * -- wdf 242 */ 243 KASSERT(event->he_size <= sizeof(event->he_entropy), 244 ("%s: event->he_size: %hhu > sizeof(event->he_entropy): %zu\n", 245 __func__, event->he_size, sizeof(event->he_entropy))); 246 randomdev_hash_iterate(&fortuna_state.fs_pool[pl].fsp_hash, 247 &event->he_somecounter, sizeof(event->he_somecounter)); 248 randomdev_hash_iterate(&fortuna_state.fs_pool[pl].fsp_hash, 249 event->he_entropy, event->he_size); 250 251 /*- 252 * Don't wrap the length. This is a "saturating" add. 253 * XXX: FIX!!: We don't actually need lengths for anything but fs_pool[0], 254 * but it's been useful debugging to see them all. 255 */ 256 fortuna_state.fs_pool[pl].fsp_length = MIN(RANDOM_FORTUNA_MAXPOOLSIZE, 257 fortuna_state.fs_pool[pl].fsp_length + 258 sizeof(event->he_somecounter) + event->he_size); 259 explicit_bzero(event, sizeof(*event)); 260 RANDOM_RESEED_UNLOCK(); 261 } 262 263 /*- 264 * FS&K - Reseed() 265 * This introduces new key material into the output generator. 266 * Additionally it increments the output generator's counter 267 * variable C. When C > 0, the output generator is seeded and 268 * will deliver output. 269 * The entropy_data buffer passed is a very specific size; the 270 * product of RANDOM_FORTUNA_NPOOLS and RANDOM_KEYSIZE. 271 */ 272 static void 273 random_fortuna_reseed_internal(uint32_t *entropy_data, u_int blockcount) 274 { 275 struct randomdev_hash context; 276 uint8_t hash[RANDOM_KEYSIZE]; 277 278 RANDOM_RESEED_ASSERT_LOCK_OWNED(); 279 /*- 280 * FS&K - K = Hd(K|s) where Hd(m) is H(H(0^512|m)) 281 * - C = C + 1 282 */ 283 randomdev_hash_init(&context); 284 randomdev_hash_iterate(&context, zero_region, RANDOM_ZERO_BLOCKSIZE); 285 randomdev_hash_iterate(&context, &fortuna_state.fs_key, sizeof(fortuna_state.fs_key)); 286 randomdev_hash_iterate(&context, entropy_data, RANDOM_KEYSIZE*blockcount); 287 randomdev_hash_finish(&context, hash); 288 randomdev_hash_init(&context); 289 randomdev_hash_iterate(&context, hash, RANDOM_KEYSIZE); 290 randomdev_hash_finish(&context, hash); 291 randomdev_encrypt_init(&fortuna_state.fs_key, hash); 292 explicit_bzero(hash, sizeof(hash)); 293 /* Unblock the device if this is the first time we are reseeding. */ 294 if (uint128_is_zero(fortuna_state.fs_counter)) 295 randomdev_unblock(); 296 uint128_increment(&fortuna_state.fs_counter); 297 } 298 299 /*- 300 * FS&K - GenerateBlocks() 301 * Generate a number of complete blocks of random output. 302 */ 303 static __inline void 304 random_fortuna_genblocks(uint8_t *buf, u_int blockcount) 305 { 306 u_int i; 307 308 RANDOM_RESEED_ASSERT_LOCK_OWNED(); 309 for (i = 0; i < blockcount; i++) { 310 /*- 311 * FS&K - r = r|E(K,C) 312 * - C = C + 1 313 */ 314 randomdev_encrypt(&fortuna_state.fs_key, &fortuna_state.fs_counter, buf, RANDOM_BLOCKSIZE); 315 buf += RANDOM_BLOCKSIZE; 316 uint128_increment(&fortuna_state.fs_counter); 317 } 318 } 319 320 /*- 321 * FS&K - PseudoRandomData() 322 * This generates no more than 2^20 bytes of data, and cleans up its 323 * internal state when finished. It is assumed that a whole number of 324 * blocks are available for writing; any excess generated will be 325 * ignored. 326 */ 327 static __inline void 328 random_fortuna_genrandom(uint8_t *buf, u_int bytecount) 329 { 330 static uint8_t temp[RANDOM_BLOCKSIZE*(RANDOM_KEYS_PER_BLOCK)]; 331 u_int blockcount; 332 333 RANDOM_RESEED_ASSERT_LOCK_OWNED(); 334 /*- 335 * FS&K - assert(n < 2^20 (== 1 MB) 336 * - r = first-n-bytes(GenerateBlocks(ceil(n/16))) 337 * - K = GenerateBlocks(2) 338 */ 339 KASSERT((bytecount <= RANDOM_FORTUNA_MAX_READ), ("invalid single read request to Fortuna of %d bytes", bytecount)); 340 blockcount = howmany(bytecount, RANDOM_BLOCKSIZE); 341 random_fortuna_genblocks(buf, blockcount); 342 random_fortuna_genblocks(temp, RANDOM_KEYS_PER_BLOCK); 343 randomdev_encrypt_init(&fortuna_state.fs_key, temp); 344 explicit_bzero(temp, sizeof(temp)); 345 } 346 347 /*- 348 * FS&K - RandomData() (Part 1) 349 * Used to return processed entropy from the PRNG. There is a pre_read 350 * required to be present (but it can be a stub) in order to allow 351 * specific actions at the begin of the read. 352 */ 353 void 354 random_fortuna_pre_read(void) 355 { 356 #ifdef _KERNEL 357 sbintime_t now; 358 #endif 359 struct randomdev_hash context; 360 uint32_t s[RANDOM_FORTUNA_NPOOLS*RANDOM_KEYSIZE_WORDS]; 361 uint8_t temp[RANDOM_KEYSIZE]; 362 u_int i; 363 364 KASSERT(fortuna_state.fs_minpoolsize > 0, ("random: Fortuna threshold must be > 0")); 365 #ifdef _KERNEL 366 /* FS&K - Use 'getsbinuptime()' to prevent reseed-spamming. */ 367 now = getsbinuptime(); 368 #endif 369 RANDOM_RESEED_LOCK(); 370 371 if (fortuna_state.fs_pool[0].fsp_length >= fortuna_state.fs_minpoolsize 372 #ifdef _KERNEL 373 /* FS&K - Use 'getsbinuptime()' to prevent reseed-spamming. */ 374 && (now - fortuna_state.fs_lasttime > hz/10) 375 #endif 376 ) { 377 #ifdef _KERNEL 378 fortuna_state.fs_lasttime = now; 379 #endif 380 381 /* FS&K - ReseedCNT = ReseedCNT + 1 */ 382 fortuna_state.fs_reseedcount++; 383 /* s = \epsilon at start */ 384 for (i = 0; i < RANDOM_FORTUNA_NPOOLS; i++) { 385 /* FS&K - if Divides(ReseedCnt, 2^i) ... */ 386 if ((fortuna_state.fs_reseedcount % (1 << i)) == 0) { 387 /*- 388 * FS&K - temp = (P_i) 389 * - P_i = \epsilon 390 * - s = s|H(temp) 391 */ 392 randomdev_hash_finish(&fortuna_state.fs_pool[i].fsp_hash, temp); 393 randomdev_hash_init(&fortuna_state.fs_pool[i].fsp_hash); 394 fortuna_state.fs_pool[i].fsp_length = 0; 395 randomdev_hash_init(&context); 396 randomdev_hash_iterate(&context, temp, RANDOM_KEYSIZE); 397 randomdev_hash_finish(&context, s + i*RANDOM_KEYSIZE_WORDS); 398 } else 399 break; 400 } 401 SDT_PROBE2(random, fortuna, event_processor, debug, fortuna_state.fs_reseedcount, fortuna_state.fs_pool); 402 /* FS&K */ 403 random_fortuna_reseed_internal(s, i < RANDOM_FORTUNA_NPOOLS ? i + 1 : RANDOM_FORTUNA_NPOOLS); 404 /* Clean up and secure */ 405 explicit_bzero(s, sizeof(s)); 406 explicit_bzero(temp, sizeof(temp)); 407 explicit_bzero(&context, sizeof(context)); 408 } 409 RANDOM_RESEED_UNLOCK(); 410 } 411 412 /*- 413 * FS&K - RandomData() (Part 2) 414 * Main read from Fortuna, continued. May be called multiple times after 415 * the random_fortuna_pre_read() above. 416 * The supplied buf MUST be a multiple of RANDOM_BLOCKSIZE in size. 417 * Lots of code presumes this for efficiency, both here and in other 418 * routines. You are NOT allowed to break this! 419 */ 420 void 421 random_fortuna_read(uint8_t *buf, u_int bytecount) 422 { 423 424 KASSERT((bytecount % RANDOM_BLOCKSIZE) == 0, ("%s(): bytecount (= %d) must be a multiple of %d", __func__, bytecount, RANDOM_BLOCKSIZE )); 425 RANDOM_RESEED_LOCK(); 426 random_fortuna_genrandom(buf, bytecount); 427 RANDOM_RESEED_UNLOCK(); 428 } 429 430 bool 431 random_fortuna_seeded(void) 432 { 433 434 return (!uint128_is_zero(fortuna_state.fs_counter)); 435 } 436