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/param.h> 39 #include <sys/limits.h> 40 41 #ifdef _KERNEL 42 #include <sys/fail.h> 43 #include <sys/kernel.h> 44 #include <sys/lock.h> 45 #include <sys/malloc.h> 46 #include <sys/mutex.h> 47 #include <sys/random.h> 48 #include <sys/sdt.h> 49 #include <sys/sysctl.h> 50 #include <sys/systm.h> 51 52 #include <machine/cpu.h> 53 #else /* !_KERNEL */ 54 #include <inttypes.h> 55 #include <stdbool.h> 56 #include <stdio.h> 57 #include <stdlib.h> 58 #include <string.h> 59 #include <threads.h> 60 61 #include "unit_test.h" 62 #endif /* _KERNEL */ 63 64 #include <crypto/rijndael/rijndael-api-fst.h> 65 #include <crypto/sha2/sha256.h> 66 67 #include <dev/random/hash.h> 68 #include <dev/random/randomdev.h> 69 #ifdef _KERNEL 70 #include <dev/random/random_harvestq.h> 71 #endif 72 #include <dev/random/uint128.h> 73 #include <dev/random/fortuna.h> 74 75 /* Defined in FS&K */ 76 #define RANDOM_FORTUNA_NPOOLS 32 /* The number of accumulation pools */ 77 #define RANDOM_FORTUNA_DEFPOOLSIZE 64 /* The default pool size/length for a (re)seed */ 78 #define RANDOM_FORTUNA_MAX_READ (1 << 20) /* Max bytes in a single read */ 79 80 /* 81 * The allowable range of RANDOM_FORTUNA_DEFPOOLSIZE. The default value is above. 82 * Making RANDOM_FORTUNA_DEFPOOLSIZE too large will mean a long time between reseeds, 83 * and too small may compromise initial security but get faster reseeds. 84 */ 85 #define RANDOM_FORTUNA_MINPOOLSIZE 16 86 #define RANDOM_FORTUNA_MAXPOOLSIZE INT_MAX 87 CTASSERT(RANDOM_FORTUNA_MINPOOLSIZE <= RANDOM_FORTUNA_DEFPOOLSIZE); 88 CTASSERT(RANDOM_FORTUNA_DEFPOOLSIZE <= RANDOM_FORTUNA_MAXPOOLSIZE); 89 90 /* This algorithm (and code) presumes that RANDOM_KEYSIZE is twice as large as RANDOM_BLOCKSIZE */ 91 CTASSERT(RANDOM_BLOCKSIZE == sizeof(uint128_t)); 92 CTASSERT(RANDOM_KEYSIZE == 2*RANDOM_BLOCKSIZE); 93 94 /* Probes for dtrace(1) */ 95 #ifdef _KERNEL 96 SDT_PROVIDER_DECLARE(random); 97 SDT_PROVIDER_DEFINE(random); 98 SDT_PROBE_DEFINE2(random, fortuna, event_processor, debug, "u_int", "struct fs_pool *"); 99 #endif /* _KERNEL */ 100 101 /* 102 * This is the beastie that needs protecting. It contains all of the 103 * state that we are excited about. Exactly one is instantiated. 104 */ 105 static struct fortuna_state { 106 struct fs_pool { /* P_i */ 107 u_int fsp_length; /* Only the first one is used by Fortuna */ 108 struct randomdev_hash fsp_hash; 109 } fs_pool[RANDOM_FORTUNA_NPOOLS]; 110 u_int fs_reseedcount; /* ReseedCnt */ 111 uint128_t fs_counter; /* C */ 112 union randomdev_key fs_key; /* K */ 113 u_int fs_minpoolsize; /* Extras */ 114 /* Extras for the OS */ 115 #ifdef _KERNEL 116 /* For use when 'pacing' the reseeds */ 117 sbintime_t fs_lasttime; 118 #endif 119 /* Reseed lock */ 120 mtx_t fs_mtx; 121 } fortuna_state; 122 123 #ifdef _KERNEL 124 static struct sysctl_ctx_list random_clist; 125 RANDOM_CHECK_UINT(fs_minpoolsize, RANDOM_FORTUNA_MINPOOLSIZE, RANDOM_FORTUNA_MAXPOOLSIZE); 126 #else 127 static uint8_t zero_region[RANDOM_ZERO_BLOCKSIZE]; 128 #endif 129 130 static void random_fortuna_pre_read(void); 131 static void random_fortuna_read(uint8_t *, u_int); 132 static bool random_fortuna_seeded(void); 133 static void random_fortuna_process_event(struct harvest_event *); 134 static void random_fortuna_init_alg(void *); 135 static void random_fortuna_deinit_alg(void *); 136 137 static void random_fortuna_reseed_internal(uint32_t *entropy_data, u_int blockcount); 138 139 struct random_algorithm random_alg_context = { 140 .ra_ident = "Fortuna", 141 .ra_init_alg = random_fortuna_init_alg, 142 .ra_deinit_alg = random_fortuna_deinit_alg, 143 .ra_pre_read = random_fortuna_pre_read, 144 .ra_read = random_fortuna_read, 145 .ra_seeded = random_fortuna_seeded, 146 .ra_event_processor = random_fortuna_process_event, 147 .ra_poolcount = RANDOM_FORTUNA_NPOOLS, 148 }; 149 150 /* ARGSUSED */ 151 static void 152 random_fortuna_init_alg(void *unused __unused) 153 { 154 int i; 155 #ifdef _KERNEL 156 struct sysctl_oid *random_fortuna_o; 157 #endif 158 159 RANDOM_RESEED_INIT_LOCK(); 160 /* 161 * Fortuna parameters. Do not adjust these unless you have 162 * have a very good clue about what they do! 163 */ 164 fortuna_state.fs_minpoolsize = RANDOM_FORTUNA_DEFPOOLSIZE; 165 #ifdef _KERNEL 166 fortuna_state.fs_lasttime = 0; 167 random_fortuna_o = SYSCTL_ADD_NODE(&random_clist, 168 SYSCTL_STATIC_CHILDREN(_kern_random), 169 OID_AUTO, "fortuna", CTLFLAG_RW, 0, 170 "Fortuna Parameters"); 171 SYSCTL_ADD_PROC(&random_clist, 172 SYSCTL_CHILDREN(random_fortuna_o), OID_AUTO, 173 "minpoolsize", CTLTYPE_UINT | CTLFLAG_RWTUN, 174 &fortuna_state.fs_minpoolsize, RANDOM_FORTUNA_DEFPOOLSIZE, 175 random_check_uint_fs_minpoolsize, "IU", 176 "Minimum pool size necessary to cause a reseed"); 177 KASSERT(fortuna_state.fs_minpoolsize > 0, ("random: Fortuna threshold must be > 0 at startup")); 178 #endif 179 180 /*- 181 * FS&K - InitializePRNG() 182 * - P_i = \epsilon 183 * - ReseedCNT = 0 184 */ 185 for (i = 0; i < RANDOM_FORTUNA_NPOOLS; i++) { 186 randomdev_hash_init(&fortuna_state.fs_pool[i].fsp_hash); 187 fortuna_state.fs_pool[i].fsp_length = 0; 188 } 189 fortuna_state.fs_reseedcount = 0; 190 /*- 191 * FS&K - InitializeGenerator() 192 * - C = 0 193 * - K = 0 194 */ 195 fortuna_state.fs_counter = UINT128_ZERO; 196 explicit_bzero(&fortuna_state.fs_key, sizeof(fortuna_state.fs_key)); 197 } 198 199 /* ARGSUSED */ 200 static void 201 random_fortuna_deinit_alg(void *unused __unused) 202 { 203 204 RANDOM_RESEED_DEINIT_LOCK(); 205 explicit_bzero(&fortuna_state, sizeof(fortuna_state)); 206 #ifdef _KERNEL 207 sysctl_ctx_free(&random_clist); 208 #endif 209 } 210 211 /*- 212 * FS&K - AddRandomEvent() 213 * Process a single stochastic event off the harvest queue 214 */ 215 static void 216 random_fortuna_process_event(struct harvest_event *event) 217 { 218 u_int pl; 219 220 RANDOM_RESEED_LOCK(); 221 /*- 222 * FS&K - P_i = P_i|<harvested stuff> 223 * Accumulate the event into the appropriate pool 224 * where each event carries the destination information. 225 * 226 * The hash_init() and hash_finish() calls are done in 227 * random_fortuna_pre_read(). 228 * 229 * We must be locked against pool state modification which can happen 230 * during accumulation/reseeding and reading/regating. 231 */ 232 pl = event->he_destination % RANDOM_FORTUNA_NPOOLS; 233 /* 234 * We ignore low entropy static/counter fields towards the end of the 235 * he_event structure in order to increase measurable entropy when 236 * conducting SP800-90B entropy analysis measurements of seed material 237 * fed into PRNG. 238 * -- wdf 239 */ 240 KASSERT(event->he_size <= sizeof(event->he_entropy), 241 ("%s: event->he_size: %hhu > sizeof(event->he_entropy): %zu\n", 242 __func__, event->he_size, sizeof(event->he_entropy))); 243 randomdev_hash_iterate(&fortuna_state.fs_pool[pl].fsp_hash, 244 &event->he_somecounter, sizeof(event->he_somecounter)); 245 randomdev_hash_iterate(&fortuna_state.fs_pool[pl].fsp_hash, 246 event->he_entropy, event->he_size); 247 248 /*- 249 * Don't wrap the length. This is a "saturating" add. 250 * XXX: FIX!!: We don't actually need lengths for anything but fs_pool[0], 251 * but it's been useful debugging to see them all. 252 */ 253 fortuna_state.fs_pool[pl].fsp_length = MIN(RANDOM_FORTUNA_MAXPOOLSIZE, 254 fortuna_state.fs_pool[pl].fsp_length + 255 sizeof(event->he_somecounter) + event->he_size); 256 explicit_bzero(event, sizeof(*event)); 257 RANDOM_RESEED_UNLOCK(); 258 } 259 260 /*- 261 * FS&K - Reseed() 262 * This introduces new key material into the output generator. 263 * Additionally it increments the output generator's counter 264 * variable C. When C > 0, the output generator is seeded and 265 * will deliver output. 266 * The entropy_data buffer passed is a very specific size; the 267 * product of RANDOM_FORTUNA_NPOOLS and RANDOM_KEYSIZE. 268 */ 269 static void 270 random_fortuna_reseed_internal(uint32_t *entropy_data, u_int blockcount) 271 { 272 struct randomdev_hash context; 273 uint8_t hash[RANDOM_KEYSIZE]; 274 const void *keymaterial; 275 size_t keysz; 276 bool seeded; 277 278 RANDOM_RESEED_ASSERT_LOCK_OWNED(); 279 280 seeded = random_fortuna_seeded(); 281 if (seeded) { 282 randomdev_getkey(&fortuna_state.fs_key, &keymaterial, &keysz); 283 KASSERT(keysz == RANDOM_KEYSIZE, ("%s: key size %zu not %u", 284 __func__, keysz, (unsigned)RANDOM_KEYSIZE)); 285 } 286 287 /*- 288 * FS&K - K = Hd(K|s) where Hd(m) is H(H(0^512|m)) 289 * - C = C + 1 290 */ 291 randomdev_hash_init(&context); 292 randomdev_hash_iterate(&context, zero_region, RANDOM_ZERO_BLOCKSIZE); 293 if (seeded) 294 randomdev_hash_iterate(&context, keymaterial, keysz); 295 randomdev_hash_iterate(&context, entropy_data, RANDOM_KEYSIZE*blockcount); 296 randomdev_hash_finish(&context, hash); 297 randomdev_hash_init(&context); 298 randomdev_hash_iterate(&context, hash, RANDOM_KEYSIZE); 299 randomdev_hash_finish(&context, hash); 300 randomdev_encrypt_init(&fortuna_state.fs_key, hash); 301 explicit_bzero(hash, sizeof(hash)); 302 /* Unblock the device if this is the first time we are reseeding. */ 303 if (uint128_is_zero(fortuna_state.fs_counter)) 304 randomdev_unblock(); 305 uint128_increment(&fortuna_state.fs_counter); 306 } 307 308 /*- 309 * FS&K - GenerateBlocks() 310 * Generate a number of complete blocks of random output. 311 */ 312 static __inline void 313 random_fortuna_genblocks(uint8_t *buf, u_int blockcount) 314 { 315 316 RANDOM_RESEED_ASSERT_LOCK_OWNED(); 317 KASSERT(!uint128_is_zero(fortuna_state.fs_counter), ("FS&K: C != 0")); 318 319 /* 320 * Fills buf with RANDOM_BLOCKSIZE * blockcount bytes of keystream. 321 * Increments fs_counter as it goes. 322 */ 323 randomdev_keystream(&fortuna_state.fs_key, &fortuna_state.fs_counter, 324 buf, blockcount); 325 } 326 327 /*- 328 * FS&K - PseudoRandomData() 329 * This generates no more than 2^20 bytes of data, and cleans up its 330 * internal state when finished. It is assumed that a whole number of 331 * blocks are available for writing; any excess generated will be 332 * ignored. 333 */ 334 static __inline void 335 random_fortuna_genrandom(uint8_t *buf, u_int bytecount) 336 { 337 uint8_t temp[RANDOM_BLOCKSIZE * RANDOM_KEYS_PER_BLOCK]; 338 u_int blockcount; 339 340 RANDOM_RESEED_ASSERT_LOCK_OWNED(); 341 /*- 342 * FS&K - assert(n < 2^20 (== 1 MB) 343 * - r = first-n-bytes(GenerateBlocks(ceil(n/16))) 344 * - K = GenerateBlocks(2) 345 */ 346 KASSERT((bytecount <= RANDOM_FORTUNA_MAX_READ), ("invalid single read request to Fortuna of %d bytes", bytecount)); 347 blockcount = howmany(bytecount, RANDOM_BLOCKSIZE); 348 random_fortuna_genblocks(buf, blockcount); 349 random_fortuna_genblocks(temp, RANDOM_KEYS_PER_BLOCK); 350 randomdev_encrypt_init(&fortuna_state.fs_key, temp); 351 explicit_bzero(temp, sizeof(temp)); 352 } 353 354 /*- 355 * FS&K - RandomData() (Part 1) 356 * Used to return processed entropy from the PRNG. There is a pre_read 357 * required to be present (but it can be a stub) in order to allow 358 * specific actions at the begin of the read. 359 */ 360 void 361 random_fortuna_pre_read(void) 362 { 363 #ifdef _KERNEL 364 sbintime_t now; 365 #endif 366 struct randomdev_hash context; 367 uint32_t s[RANDOM_FORTUNA_NPOOLS*RANDOM_KEYSIZE_WORDS]; 368 uint8_t temp[RANDOM_KEYSIZE]; 369 u_int i; 370 371 KASSERT(fortuna_state.fs_minpoolsize > 0, ("random: Fortuna threshold must be > 0")); 372 RANDOM_RESEED_LOCK(); 373 #ifdef _KERNEL 374 /* FS&K - Use 'getsbinuptime()' to prevent reseed-spamming. */ 375 now = getsbinuptime(); 376 #endif 377 378 if (fortuna_state.fs_pool[0].fsp_length < fortuna_state.fs_minpoolsize 379 #ifdef _KERNEL 380 /* FS&K - Use 'getsbinuptime()' to prevent reseed-spamming. */ 381 || (now - fortuna_state.fs_lasttime <= SBT_1S/10) 382 #endif 383 ) { 384 RANDOM_RESEED_UNLOCK(); 385 return; 386 } 387 388 #ifdef _KERNEL 389 /* 390 * When set, pretend we do not have enough entropy to reseed yet. 391 */ 392 KFAIL_POINT_CODE(DEBUG_FP, random_fortuna_pre_read, { 393 if (RETURN_VALUE != 0) { 394 RANDOM_RESEED_UNLOCK(); 395 return; 396 } 397 }); 398 #endif 399 400 #ifdef _KERNEL 401 fortuna_state.fs_lasttime = now; 402 #endif 403 404 /* FS&K - ReseedCNT = ReseedCNT + 1 */ 405 fortuna_state.fs_reseedcount++; 406 /* s = \epsilon at start */ 407 for (i = 0; i < RANDOM_FORTUNA_NPOOLS; i++) { 408 /* FS&K - if Divides(ReseedCnt, 2^i) ... */ 409 if ((fortuna_state.fs_reseedcount % (1 << i)) == 0) { 410 /*- 411 * FS&K - temp = (P_i) 412 * - P_i = \epsilon 413 * - s = s|H(temp) 414 */ 415 randomdev_hash_finish(&fortuna_state.fs_pool[i].fsp_hash, temp); 416 randomdev_hash_init(&fortuna_state.fs_pool[i].fsp_hash); 417 fortuna_state.fs_pool[i].fsp_length = 0; 418 randomdev_hash_init(&context); 419 randomdev_hash_iterate(&context, temp, RANDOM_KEYSIZE); 420 randomdev_hash_finish(&context, s + i*RANDOM_KEYSIZE_WORDS); 421 } else 422 break; 423 } 424 #ifdef _KERNEL 425 SDT_PROBE2(random, fortuna, event_processor, debug, fortuna_state.fs_reseedcount, fortuna_state.fs_pool); 426 #endif 427 /* FS&K */ 428 random_fortuna_reseed_internal(s, i); 429 RANDOM_RESEED_UNLOCK(); 430 431 /* Clean up and secure */ 432 explicit_bzero(s, sizeof(s)); 433 explicit_bzero(temp, sizeof(temp)); 434 } 435 436 /*- 437 * FS&K - RandomData() (Part 2) 438 * Main read from Fortuna, continued. May be called multiple times after 439 * the random_fortuna_pre_read() above. 440 * The supplied buf MUST be a multiple of RANDOM_BLOCKSIZE in size. 441 * Lots of code presumes this for efficiency, both here and in other 442 * routines. You are NOT allowed to break this! 443 */ 444 void 445 random_fortuna_read(uint8_t *buf, u_int bytecount) 446 { 447 448 KASSERT((bytecount % RANDOM_BLOCKSIZE) == 0, ("%s(): bytecount (= %d) must be a multiple of %d", __func__, bytecount, RANDOM_BLOCKSIZE )); 449 RANDOM_RESEED_LOCK(); 450 random_fortuna_genrandom(buf, bytecount); 451 RANDOM_RESEED_UNLOCK(); 452 } 453 454 #ifdef _KERNEL 455 static bool block_seeded_status = false; 456 SYSCTL_BOOL(_kern_random, OID_AUTO, block_seeded_status, CTLFLAG_RWTUN, 457 &block_seeded_status, 0, 458 "If non-zero, pretend Fortuna is in an unseeded state. By setting " 459 "this as a tunable, boot can be tested as if the random device is " 460 "unavailable."); 461 #endif 462 463 bool 464 random_fortuna_seeded(void) 465 { 466 467 #ifdef _KERNEL 468 if (block_seeded_status) 469 return (false); 470 #endif 471 472 return (!uint128_is_zero(fortuna_state.fs_counter)); 473 } 474