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