1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 /* 22 * Copyright 2009 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 /* 27 * Software based random number provider for the Kernel Cryptographic 28 * Framework (KCF). This provider periodically collects unpredictable input 29 * from external sources and processes it into a pool of entropy (randomness) 30 * in order to satisfy requests for random bits from kCF. It implements 31 * software-based mixing, extraction, and generation algorithms. 32 * 33 * A history note: The software-based algorithms in this file used to be 34 * part of the /dev/random driver. 35 */ 36 37 #include <sys/types.h> 38 #include <sys/errno.h> 39 #include <sys/debug.h> 40 #include <vm/seg_kmem.h> 41 #include <vm/hat.h> 42 #include <sys/systm.h> 43 #include <sys/memlist.h> 44 #include <sys/cmn_err.h> 45 #include <sys/ksynch.h> 46 #include <sys/random.h> 47 #include <sys/ddi.h> 48 #include <sys/mman.h> 49 #include <sys/sysmacros.h> 50 #include <sys/mem_config.h> 51 #include <sys/time.h> 52 #include <sys/crypto/spi.h> 53 #include <sys/sha1.h> 54 #include <sys/sunddi.h> 55 #include <sys/modctl.h> 56 #include <sys/hold_page.h> 57 #include <rng/fips_random.h> 58 59 #define RNDPOOLSIZE 1024 /* Pool size in bytes */ 60 #define HASHBUFSIZE 64 /* Buffer size used for pool mixing */ 61 #define MAXMEMBLOCKS 16384 /* Number of memory blocks to scan */ 62 #define MEMBLOCKSIZE 4096 /* Size of memory block to read */ 63 #define MINEXTRACTBITS 160 /* Min entropy level for extraction */ 64 #define TIMEOUT_INTERVAL 5 /* Periodic mixing interval in secs */ 65 66 /* Hash-algo generic definitions. For now, they are SHA1's. */ 67 #define HASHSIZE 20 68 #define HASH_CTX SHA1_CTX 69 #define HashInit(ctx) SHA1Init((ctx)) 70 #define HashUpdate(ctx, p, s) SHA1Update((ctx), (p), (s)) 71 #define HashFinal(d, ctx) SHA1Final((d), (ctx)) 72 73 /* Physical memory entropy source */ 74 typedef struct physmem_entsrc_s { 75 uint8_t *parity; /* parity bit vector */ 76 caddr_t pmbuf; /* buffer for memory block */ 77 uint32_t nblocks; /* number of memory blocks */ 78 int entperblock; /* entropy bits per block read */ 79 hrtime_t last_diff; /* previous time to process a block */ 80 hrtime_t last_delta; /* previous time delta */ 81 hrtime_t last_delta2; /* previous 2nd order time delta */ 82 } physmem_entsrc_t; 83 84 static uint32_t srndpool[RNDPOOLSIZE/4]; /* Pool of random bits */ 85 static uint32_t buffer[RNDPOOLSIZE/4]; /* entropy mixed in later */ 86 static int buffer_bytes; /* bytes written to buffer */ 87 static uint32_t entropy_bits; /* pool's current amount of entropy */ 88 static kmutex_t srndpool_lock; /* protects r/w accesses to the pool, */ 89 /* and the global variables */ 90 static kmutex_t buffer_lock; /* protects r/w accesses to buffer */ 91 static kcondvar_t srndpool_read_cv; /* serializes poll/read syscalls */ 92 static int pindex; /* Global index for adding/extracting */ 93 /* from the pool */ 94 static int bstart, bindex; /* Global vars for adding/extracting */ 95 /* from the buffer */ 96 static uint8_t leftover[HASHSIZE]; /* leftover output */ 97 static uint32_t swrand_XKEY[6]; /* one extra word for getentropy */ 98 static int leftover_bytes; /* leftover length */ 99 static uint32_t previous_bytes[HASHSIZE/BYTES_IN_WORD]; /* prev random bytes */ 100 101 static physmem_entsrc_t entsrc; /* Physical mem as an entropy source */ 102 static timeout_id_t rnd_timeout_id; 103 static int snum_waiters; 104 static crypto_kcf_provider_handle_t swrand_prov_handle = NULL; 105 swrand_stats_t swrand_stats; 106 107 static int physmem_ent_init(physmem_entsrc_t *); 108 static void physmem_ent_fini(physmem_entsrc_t *); 109 static void physmem_ent_gen(physmem_entsrc_t *); 110 static int physmem_parity_update(uint8_t *, uint32_t, int); 111 static void physmem_count_blocks(); 112 static void rnd_dr_callback_post_add(void *, pgcnt_t); 113 static int rnd_dr_callback_pre_del(void *, pgcnt_t); 114 static void rnd_dr_callback_post_del(void *, pgcnt_t, int); 115 static void rnd_handler(void *arg); 116 static void swrand_init(); 117 static void swrand_schedule_timeout(void); 118 static int swrand_get_entropy(uint8_t *ptr, size_t len, boolean_t); 119 static void swrand_add_entropy(uint8_t *ptr, size_t len, uint16_t entropy_est); 120 static void swrand_add_entropy_later(uint8_t *ptr, size_t len); 121 122 /* Dynamic Reconfiguration related declarations */ 123 kphysm_setup_vector_t rnd_dr_callback_vec = { 124 KPHYSM_SETUP_VECTOR_VERSION, 125 rnd_dr_callback_post_add, 126 rnd_dr_callback_pre_del, 127 rnd_dr_callback_post_del 128 }; 129 130 extern struct mod_ops mod_cryptoops; 131 132 /* 133 * Module linkage information for the kernel. 134 */ 135 static struct modlcrypto modlcrypto = { 136 &mod_cryptoops, 137 "Kernel Random number Provider" 138 }; 139 140 static struct modlinkage modlinkage = { 141 MODREV_1, 142 (void *)&modlcrypto, 143 NULL 144 }; 145 146 /* 147 * CSPI information (entry points, provider info, etc.) 148 */ 149 static void swrand_provider_status(crypto_provider_handle_t, uint_t *); 150 151 static crypto_control_ops_t swrand_control_ops = { 152 swrand_provider_status 153 }; 154 155 static int swrand_seed_random(crypto_provider_handle_t, crypto_session_id_t, 156 uchar_t *, size_t, uint_t, uint32_t, crypto_req_handle_t); 157 static int swrand_generate_random(crypto_provider_handle_t, 158 crypto_session_id_t, uchar_t *, size_t, crypto_req_handle_t); 159 160 static crypto_random_number_ops_t swrand_random_number_ops = { 161 swrand_seed_random, 162 swrand_generate_random 163 }; 164 165 static crypto_ops_t swrand_crypto_ops = { 166 &swrand_control_ops, 167 NULL, 168 NULL, 169 NULL, 170 NULL, 171 NULL, 172 NULL, 173 NULL, 174 &swrand_random_number_ops, 175 NULL, 176 NULL, 177 NULL, 178 NULL, 179 NULL 180 }; 181 182 static crypto_provider_info_t swrand_prov_info = { 183 CRYPTO_SPI_VERSION_1, 184 "Kernel Random Number Provider", 185 CRYPTO_SW_PROVIDER, 186 {&modlinkage}, 187 NULL, 188 &swrand_crypto_ops, 189 0, 190 NULL 191 }; 192 193 int 194 _init(void) 195 { 196 int ret; 197 hrtime_t ts; 198 time_t now; 199 200 /* 201 * Register with KCF. If the registration fails, return error. 202 */ 203 if ((ret = crypto_register_provider(&swrand_prov_info, 204 &swrand_prov_handle)) != CRYPTO_SUCCESS) { 205 cmn_err(CE_WARN, "swrand : Kernel Random Number Provider " 206 "disabled for /dev/random use"); 207 return (EACCES); 208 } 209 210 mutex_init(&srndpool_lock, NULL, MUTEX_DEFAULT, NULL); 211 mutex_init(&buffer_lock, NULL, MUTEX_DEFAULT, NULL); 212 cv_init(&srndpool_read_cv, NULL, CV_DEFAULT, NULL); 213 entropy_bits = 0; 214 pindex = 0; 215 bindex = 0; 216 bstart = 0; 217 snum_waiters = 0; 218 leftover_bytes = 0; 219 buffer_bytes = 0; 220 221 /* 222 * Initialize the pool using 223 * . 2 unpredictable times: high resolution time since the boot-time, 224 * and the current time-of-the day. 225 * . The initial physical memory state. 226 */ 227 ts = gethrtime(); 228 swrand_add_entropy((uint8_t *)&ts, sizeof (ts), 0); 229 230 (void) drv_getparm(TIME, &now); 231 swrand_add_entropy((uint8_t *)&now, sizeof (now), 0); 232 233 ret = kphysm_setup_func_register(&rnd_dr_callback_vec, NULL); 234 ASSERT(ret == 0); 235 236 if (physmem_ent_init(&entsrc) != 0) { 237 mutex_destroy(&srndpool_lock); 238 mutex_destroy(&buffer_lock); 239 cv_destroy(&srndpool_read_cv); 240 (void) crypto_unregister_provider(swrand_prov_handle); 241 return (ENOMEM); 242 } 243 244 if ((ret = mod_install(&modlinkage)) != 0) { 245 mutex_destroy(&srndpool_lock); 246 mutex_destroy(&buffer_lock); 247 cv_destroy(&srndpool_read_cv); 248 physmem_ent_fini(&entsrc); 249 (void) crypto_unregister_provider(swrand_prov_handle); 250 return (ret); 251 } 252 253 /* Schedule periodic mixing of the pool. */ 254 mutex_enter(&srndpool_lock); 255 swrand_schedule_timeout(); 256 mutex_exit(&srndpool_lock); 257 (void) swrand_get_entropy((uint8_t *)swrand_XKEY, HASHSIZE, B_TRUE); 258 bcopy(swrand_XKEY, previous_bytes, HASHSIZE); 259 260 return (0); 261 } 262 263 int 264 _info(struct modinfo *modinfop) 265 { 266 return (mod_info(&modlinkage, modinfop)); 267 } 268 269 /* 270 * Control entry points. 271 */ 272 /* ARGSUSED */ 273 static void 274 swrand_provider_status(crypto_provider_handle_t provider, uint_t *status) 275 { 276 *status = CRYPTO_PROVIDER_READY; 277 } 278 279 /* 280 * Random number entry points. 281 */ 282 /* ARGSUSED */ 283 static int 284 swrand_seed_random(crypto_provider_handle_t provider, crypto_session_id_t sid, 285 uchar_t *buf, size_t len, uint_t entropy_est, uint32_t flags, 286 crypto_req_handle_t req) 287 { 288 /* The entropy estimate is always 0 in this path */ 289 if (flags & CRYPTO_SEED_NOW) 290 swrand_add_entropy(buf, len, 0); 291 else 292 swrand_add_entropy_later(buf, len); 293 return (CRYPTO_SUCCESS); 294 } 295 296 /* ARGSUSED */ 297 static int 298 swrand_generate_random(crypto_provider_handle_t provider, 299 crypto_session_id_t sid, uchar_t *buf, size_t len, crypto_req_handle_t req) 300 { 301 if (crypto_kmflag(req) == KM_NOSLEEP) 302 (void) swrand_get_entropy(buf, len, B_TRUE); 303 else 304 (void) swrand_get_entropy(buf, len, B_FALSE); 305 306 return (CRYPTO_SUCCESS); 307 } 308 309 /* 310 * Extraction of entropy from the pool. 311 * 312 * Returns "len" random bytes in *ptr. 313 * Try to gather some more entropy by calling physmem_ent_gen() when less than 314 * MINEXTRACTBITS are present in the pool. 315 * Will block if not enough entropy was available and the call is blocking. 316 */ 317 static int 318 swrand_get_entropy(uint8_t *ptr, size_t len, boolean_t nonblock) 319 { 320 int i, bytes; 321 HASH_CTX hashctx; 322 uint8_t digest[HASHSIZE], *pool; 323 uint32_t tempout[HASHSIZE/BYTES_IN_WORD]; 324 int size; 325 326 mutex_enter(&srndpool_lock); 327 if (leftover_bytes > 0) { 328 bytes = min(len, leftover_bytes); 329 bcopy(leftover, ptr, bytes); 330 len -= bytes; 331 ptr += bytes; 332 leftover_bytes -= bytes; 333 if (leftover_bytes > 0) 334 ovbcopy(leftover+bytes, leftover, leftover_bytes); 335 } 336 337 while (len > 0) { 338 339 /* Check if there is enough entropy */ 340 while (entropy_bits < MINEXTRACTBITS) { 341 342 physmem_ent_gen(&entsrc); 343 344 if (entropy_bits < MINEXTRACTBITS && 345 nonblock == B_TRUE) { 346 mutex_exit(&srndpool_lock); 347 return (EAGAIN); 348 } 349 350 if (entropy_bits < MINEXTRACTBITS) { 351 ASSERT(nonblock == B_FALSE); 352 snum_waiters++; 353 if (cv_wait_sig(&srndpool_read_cv, 354 &srndpool_lock) == 0) { 355 snum_waiters--; 356 mutex_exit(&srndpool_lock); 357 return (EINTR); 358 } 359 snum_waiters--; 360 } 361 } 362 363 /* Figure out how many bytes to extract */ 364 bytes = min(HASHSIZE, len); 365 bytes = min(bytes, entropy_bits/8); 366 entropy_bits -= bytes * 8; 367 BUMP_SWRAND_STATS(ss_entOut, bytes * 8); 368 swrand_stats.ss_entEst = entropy_bits; 369 370 /* Extract entropy by hashing pool content */ 371 HashInit(&hashctx); 372 HashUpdate(&hashctx, (uint8_t *)srndpool, RNDPOOLSIZE); 373 HashFinal(digest, &hashctx); 374 375 /* 376 * Feed the digest back into the pool so next 377 * extraction produces different result 378 */ 379 pool = (uint8_t *)srndpool; 380 for (i = 0; i < HASHSIZE; i++) { 381 pool[pindex++] ^= digest[i]; 382 /* pindex modulo RNDPOOLSIZE */ 383 pindex &= (RNDPOOLSIZE - 1); 384 } 385 386 /* LINTED E_BAD_PTR_CAST_ALIGN */ 387 fips_random_inner(swrand_XKEY, tempout, (uint32_t *)digest); 388 389 if (len >= HASHSIZE) { 390 size = HASHSIZE; 391 } else { 392 size = min(bytes, HASHSIZE); 393 } 394 395 /* 396 * FIPS 140-2: Continuous RNG test - each generation 397 * of an n-bit block shall be compared with the previously 398 * generated block. Test shall fail if any two compared 399 * n-bit blocks are equal. 400 */ 401 for (i = 0; i < HASHSIZE/BYTES_IN_WORD; i++) { 402 if (tempout[i] != previous_bytes[i]) 403 break; 404 } 405 if (i == HASHSIZE/BYTES_IN_WORD) 406 cmn_err(CE_WARN, "swrand: The value of 160-bit block " 407 "random bytes are same as the previous one.\n"); 408 409 bcopy(tempout, previous_bytes, HASHSIZE); 410 411 bcopy(tempout, ptr, size); 412 if (len < HASHSIZE) { 413 leftover_bytes = HASHSIZE - bytes; 414 bcopy(tempout + bytes, leftover, leftover_bytes); 415 } 416 417 ptr += size; 418 len -= size; 419 BUMP_SWRAND_STATS(ss_bytesOut, size); 420 } 421 422 /* Zero out sensitive information */ 423 bzero(digest, HASHSIZE); 424 bzero(tempout, HASHSIZE); 425 mutex_exit(&srndpool_lock); 426 return (0); 427 } 428 429 #define SWRAND_ADD_BYTES(ptr, len, i, pool) \ 430 ASSERT((ptr) != NULL && (len) > 0); \ 431 BUMP_SWRAND_STATS(ss_bytesIn, (len)); \ 432 while ((len)--) { \ 433 (pool)[(i)++] ^= *(ptr); \ 434 (ptr)++; \ 435 (i) &= (RNDPOOLSIZE - 1); \ 436 } 437 438 /* Write some more user-provided entropy to the pool */ 439 static void 440 swrand_add_bytes(uint8_t *ptr, size_t len) 441 { 442 uint8_t *pool = (uint8_t *)srndpool; 443 444 ASSERT(MUTEX_HELD(&srndpool_lock)); 445 SWRAND_ADD_BYTES(ptr, len, pindex, pool); 446 } 447 448 /* 449 * Add bytes to buffer. Adding the buffer to the random pool 450 * is deferred until the random pool is mixed. 451 */ 452 static void 453 swrand_add_bytes_later(uint8_t *ptr, size_t len) 454 { 455 uint8_t *pool = (uint8_t *)buffer; 456 457 ASSERT(MUTEX_HELD(&buffer_lock)); 458 SWRAND_ADD_BYTES(ptr, len, bindex, pool); 459 buffer_bytes += len; 460 } 461 462 #undef SWRAND_ADD_BYTES 463 464 /* Mix the pool */ 465 static void 466 swrand_mix_pool(uint16_t entropy_est) 467 { 468 int i, j, k, start; 469 HASH_CTX hashctx; 470 uint8_t digest[HASHSIZE]; 471 uint8_t *pool = (uint8_t *)srndpool; 472 uint8_t *bp = (uint8_t *)buffer; 473 474 ASSERT(MUTEX_HELD(&srndpool_lock)); 475 476 /* add deferred bytes */ 477 mutex_enter(&buffer_lock); 478 if (buffer_bytes > 0) { 479 if (buffer_bytes >= RNDPOOLSIZE) { 480 for (i = 0; i < RNDPOOLSIZE/4; i++) { 481 srndpool[i] ^= buffer[i]; 482 buffer[i] = 0; 483 } 484 bstart = bindex = 0; 485 } else { 486 for (i = 0; i < buffer_bytes; i++) { 487 pool[pindex++] ^= bp[bstart]; 488 bp[bstart++] = 0; 489 pindex &= (RNDPOOLSIZE - 1); 490 bstart &= (RNDPOOLSIZE - 1); 491 } 492 ASSERT(bstart == bindex); 493 } 494 buffer_bytes = 0; 495 } 496 mutex_exit(&buffer_lock); 497 498 start = 0; 499 for (i = 0; i < RNDPOOLSIZE/HASHSIZE + 1; i++) { 500 HashInit(&hashctx); 501 502 /* Hash a buffer centered on a block in the pool */ 503 if (start + HASHBUFSIZE <= RNDPOOLSIZE) 504 HashUpdate(&hashctx, &pool[start], HASHBUFSIZE); 505 else { 506 HashUpdate(&hashctx, &pool[start], 507 RNDPOOLSIZE - start); 508 HashUpdate(&hashctx, pool, 509 HASHBUFSIZE - RNDPOOLSIZE + start); 510 } 511 HashFinal(digest, &hashctx); 512 513 /* XOR the hash result back into the block */ 514 k = (start + HASHSIZE) & (RNDPOOLSIZE - 1); 515 for (j = 0; j < HASHSIZE; j++) { 516 pool[k++] ^= digest[j]; 517 k &= (RNDPOOLSIZE - 1); 518 } 519 520 /* Slide the hash buffer and repeat with next block */ 521 start = (start + HASHSIZE) & (RNDPOOLSIZE - 1); 522 } 523 524 entropy_bits += entropy_est; 525 if (entropy_bits > RNDPOOLSIZE * 8) 526 entropy_bits = RNDPOOLSIZE * 8; 527 528 swrand_stats.ss_entEst = entropy_bits; 529 BUMP_SWRAND_STATS(ss_entIn, entropy_est); 530 } 531 532 static void 533 swrand_add_entropy_later(uint8_t *ptr, size_t len) 534 { 535 mutex_enter(&buffer_lock); 536 swrand_add_bytes_later(ptr, len); 537 mutex_exit(&buffer_lock); 538 } 539 540 static void 541 swrand_add_entropy(uint8_t *ptr, size_t len, uint16_t entropy_est) 542 { 543 mutex_enter(&srndpool_lock); 544 swrand_add_bytes(ptr, len); 545 swrand_mix_pool(entropy_est); 546 mutex_exit(&srndpool_lock); 547 } 548 549 /* 550 * The physmem_* routines below generate entropy by reading blocks of 551 * physical memory. Entropy is gathered in a couple of ways: 552 * 553 * - By reading blocks of physical memory and detecting if changes 554 * occurred in the blocks read. 555 * 556 * - By measuring the time it takes to load and hash a block of memory 557 * and computing the differences in the measured time. 558 * 559 * The first method was used in the CryptoRand implementation. Physical 560 * memory is divided into blocks of fixed size. A block of memory is 561 * chosen from the possible blocks and hashed to produce a digest. This 562 * digest is then mixed into the pool. A single bit from the digest is 563 * used as a parity bit or "checksum" and compared against the previous 564 * "checksum" computed for the block. If the single-bit checksum has not 565 * changed, no entropy is credited to the pool. If there is a change, 566 * then the assumption is that at least one bit in the block has changed. 567 * The possible locations within the memory block of where the bit change 568 * occurred is used as a measure of entropy. For example, if a block 569 * size of 4096 bytes is used, about log_2(4096*8)=15 bits worth of 570 * entropy is available. Because the single-bit checksum will miss half 571 * of the changes, the amount of entropy credited to the pool is doubled 572 * when a change is detected. With a 4096 byte block size, a block 573 * change will add a total of 30 bits of entropy to the pool. 574 * 575 * The second method measures the amount of time it takes to read and 576 * hash a physical memory block (as described above). The time measured 577 * can vary depending on system load, scheduling and other factors. 578 * Differences between consecutive measurements are computed to come up 579 * with an entropy estimate. The first, second, and third order delta is 580 * calculated to determine the minimum delta value. The number of bits 581 * present in this minimum delta value is the entropy estimate. This 582 * entropy estimation technique using time deltas is similar to that used 583 * in /dev/random implementations from Linux/BSD. 584 */ 585 586 static int 587 physmem_ent_init(physmem_entsrc_t *entsrc) 588 { 589 uint8_t *ptr; 590 int i; 591 592 bzero(entsrc, sizeof (*entsrc)); 593 594 /* 595 * The maximum entropy amount in bits per block of memory read is 596 * log_2(MEMBLOCKSIZE * 8); 597 */ 598 i = MEMBLOCKSIZE << 3; 599 while (i >>= 1) 600 entsrc->entperblock++; 601 602 /* Initialize entsrc->nblocks */ 603 physmem_count_blocks(); 604 605 if (entsrc->nblocks == 0) { 606 cmn_err(CE_WARN, "no memory blocks to scan!"); 607 return (-1); 608 } 609 610 /* Allocate space for the parity vector and memory page */ 611 entsrc->parity = kmem_alloc(howmany(entsrc->nblocks, 8), 612 KM_SLEEP); 613 entsrc->pmbuf = vmem_alloc(heap_arena, PAGESIZE, VM_SLEEP); 614 615 616 /* Initialize parity vector with bits from the pool */ 617 i = howmany(entsrc->nblocks, 8); 618 ptr = entsrc->parity; 619 while (i > 0) { 620 if (i > RNDPOOLSIZE) { 621 bcopy(srndpool, ptr, RNDPOOLSIZE); 622 mutex_enter(&srndpool_lock); 623 swrand_mix_pool(0); 624 mutex_exit(&srndpool_lock); 625 ptr += RNDPOOLSIZE; 626 i -= RNDPOOLSIZE; 627 } else { 628 bcopy(srndpool, ptr, i); 629 break; 630 } 631 } 632 633 /* Generate some entropy to further initialize the pool */ 634 mutex_enter(&srndpool_lock); 635 physmem_ent_gen(entsrc); 636 entropy_bits = 0; 637 mutex_exit(&srndpool_lock); 638 639 return (0); 640 } 641 642 static void 643 physmem_ent_fini(physmem_entsrc_t *entsrc) 644 { 645 if (entsrc->pmbuf != NULL) 646 vmem_free(heap_arena, entsrc->pmbuf, PAGESIZE); 647 if (entsrc->parity != NULL) 648 kmem_free(entsrc->parity, howmany(entsrc->nblocks, 8)); 649 bzero(entsrc, sizeof (*entsrc)); 650 } 651 652 static void 653 physmem_ent_gen(physmem_entsrc_t *entsrc) 654 { 655 struct memlist *pmem; 656 offset_t offset, poffset; 657 pfn_t pfn; 658 int i, nbytes, len, ent = 0; 659 uint32_t block, oblock; 660 hrtime_t ts1, ts2, diff, delta, delta2, delta3; 661 uint8_t digest[HASHSIZE]; 662 HASH_CTX ctx; 663 page_t *pp; 664 665 /* 666 * Use each 32-bit quantity in the pool to pick a memory 667 * block to read. 668 */ 669 for (i = 0; i < RNDPOOLSIZE/4; i++) { 670 671 /* If the pool is "full", stop after one block */ 672 if (entropy_bits + ent >= RNDPOOLSIZE * 8) { 673 if (i > 0) 674 break; 675 } 676 677 /* 678 * This lock protects reading of phys_install. 679 * Any changes to this list, by DR, are done while 680 * holding this lock. So, holding this lock is sufficient 681 * to handle DR also. 682 */ 683 memlist_read_lock(); 684 685 /* We're left with less than 4K of memory after DR */ 686 ASSERT(entsrc->nblocks > 0); 687 688 /* Pick a memory block to read */ 689 block = oblock = srndpool[i] % entsrc->nblocks; 690 691 for (pmem = phys_install; pmem != NULL; pmem = pmem->next) { 692 if (block < pmem->size / MEMBLOCKSIZE) 693 break; 694 block -= pmem->size / MEMBLOCKSIZE; 695 } 696 697 ASSERT(pmem != NULL); 698 699 offset = pmem->address + block * MEMBLOCKSIZE; 700 701 if (!address_in_memlist(phys_install, offset, MEMBLOCKSIZE)) { 702 memlist_read_unlock(); 703 continue; 704 } 705 706 /* 707 * Do an initial check to see if the address is safe 708 */ 709 if (plat_hold_page(offset >> PAGESHIFT, PLAT_HOLD_NO_LOCK, NULL) 710 == PLAT_HOLD_FAIL) { 711 memlist_read_unlock(); 712 continue; 713 } 714 715 /* 716 * Figure out which page to load to read the 717 * memory block. Load the page and compute the 718 * hash of the memory block. 719 */ 720 len = MEMBLOCKSIZE; 721 ts1 = gethrtime(); 722 HashInit(&ctx); 723 while (len) { 724 pfn = offset >> PAGESHIFT; 725 poffset = offset & PAGEOFFSET; 726 nbytes = PAGESIZE - poffset < len ? 727 PAGESIZE - poffset : len; 728 729 /* 730 * Re-check the offset, and lock the frame. If the 731 * page was given away after the above check, we'll 732 * just bail out. 733 */ 734 if (plat_hold_page(pfn, PLAT_HOLD_LOCK, &pp) == 735 PLAT_HOLD_FAIL) 736 break; 737 738 hat_devload(kas.a_hat, entsrc->pmbuf, 739 PAGESIZE, pfn, PROT_READ, 740 HAT_LOAD_NOCONSIST | HAT_LOAD_LOCK); 741 742 HashUpdate(&ctx, (uint8_t *)entsrc->pmbuf + poffset, 743 nbytes); 744 745 hat_unload(kas.a_hat, entsrc->pmbuf, PAGESIZE, 746 HAT_UNLOAD_UNLOCK); 747 748 plat_release_page(pp); 749 750 len -= nbytes; 751 offset += nbytes; 752 } 753 /* We got our pages. Let the DR roll */ 754 memlist_read_unlock(); 755 756 /* See if we had to bail out due to a page being given away */ 757 if (len) 758 continue; 759 760 HashFinal(digest, &ctx); 761 ts2 = gethrtime(); 762 763 /* 764 * Compute the time it took to load and hash the 765 * block and compare it against the previous 766 * measurement. The delta of the time values 767 * provides a small amount of entropy. The 768 * minimum of the first, second, and third order 769 * delta is used to estimate how much entropy 770 * is present. 771 */ 772 diff = ts2 - ts1; 773 delta = diff - entsrc->last_diff; 774 if (delta < 0) 775 delta = -delta; 776 delta2 = delta - entsrc->last_delta; 777 if (delta2 < 0) 778 delta2 = -delta2; 779 delta3 = delta2 - entsrc->last_delta2; 780 if (delta3 < 0) 781 delta3 = -delta3; 782 entsrc->last_diff = diff; 783 entsrc->last_delta = delta; 784 entsrc->last_delta2 = delta2; 785 786 if (delta > delta2) 787 delta = delta2; 788 if (delta > delta3) 789 delta = delta3; 790 delta2 = 0; 791 while (delta >>= 1) 792 delta2++; 793 ent += delta2; 794 795 /* 796 * If the memory block has changed, credit the pool with 797 * the entropy estimate. The entropy estimate is doubled 798 * because the single-bit checksum misses half the change 799 * on average. 800 */ 801 if (physmem_parity_update(entsrc->parity, oblock, 802 digest[0] & 1)) 803 ent += 2 * entsrc->entperblock; 804 805 /* Add the entropy bytes to the pool */ 806 swrand_add_bytes(digest, HASHSIZE); 807 swrand_add_bytes((uint8_t *)&ts1, sizeof (ts1)); 808 swrand_add_bytes((uint8_t *)&ts2, sizeof (ts2)); 809 } 810 811 swrand_mix_pool(ent); 812 } 813 814 static int 815 physmem_parity_update(uint8_t *parity_vec, uint32_t block, int parity) 816 { 817 /* Test and set the parity bit, return 1 if changed */ 818 if (parity == ((parity_vec[block >> 3] >> (block & 7)) & 1)) 819 return (0); 820 parity_vec[block >> 3] ^= 1 << (block & 7); 821 return (1); 822 } 823 824 /* Compute number of memory blocks available to scan */ 825 static void 826 physmem_count_blocks() 827 { 828 struct memlist *pmem; 829 830 memlist_read_lock(); 831 entsrc.nblocks = 0; 832 for (pmem = phys_install; pmem != NULL; pmem = pmem->next) { 833 entsrc.nblocks += pmem->size / MEMBLOCKSIZE; 834 if (entsrc.nblocks > MAXMEMBLOCKS) { 835 entsrc.nblocks = MAXMEMBLOCKS; 836 break; 837 } 838 } 839 memlist_read_unlock(); 840 } 841 842 /* 843 * Dynamic Reconfiguration call-back functions 844 */ 845 846 /* ARGSUSED */ 847 static void 848 rnd_dr_callback_post_add(void *arg, pgcnt_t delta) 849 { 850 /* More memory is available now, so update entsrc->nblocks. */ 851 physmem_count_blocks(); 852 } 853 854 /* Call-back routine invoked before the DR starts a memory removal. */ 855 /* ARGSUSED */ 856 static int 857 rnd_dr_callback_pre_del(void *arg, pgcnt_t delta) 858 { 859 return (0); 860 } 861 862 /* Call-back routine invoked after the DR starts a memory removal. */ 863 /* ARGSUSED */ 864 static void 865 rnd_dr_callback_post_del(void *arg, pgcnt_t delta, int cancelled) 866 { 867 /* Memory has shrunk, so update entsrc->nblocks. */ 868 physmem_count_blocks(); 869 } 870 871 /* Timeout handling to gather entropy from physmem events */ 872 static void 873 swrand_schedule_timeout(void) 874 { 875 clock_t ut; /* time in microseconds */ 876 877 ASSERT(MUTEX_HELD(&srndpool_lock)); 878 /* 879 * The new timeout value is taken from the pool of random bits. 880 * We're merely reading the first 32 bits from the pool here, not 881 * consuming any entropy. 882 * This routine is usually called right after stirring the pool, so 883 * srndpool[0] will have a *fresh* random value each time. 884 * The timeout multiplier value is a random value between 0.7 sec and 885 * 1.748575 sec (0.7 sec + 0xFFFFF microseconds). 886 * The new timeout is TIMEOUT_INTERVAL times that multiplier. 887 */ 888 ut = 700000 + (clock_t)(srndpool[0] & 0xFFFFF); 889 rnd_timeout_id = timeout(rnd_handler, NULL, 890 TIMEOUT_INTERVAL * drv_usectohz(ut)); 891 } 892 893 /*ARGSUSED*/ 894 static void 895 rnd_handler(void *arg) 896 { 897 mutex_enter(&srndpool_lock); 898 899 physmem_ent_gen(&entsrc); 900 if (snum_waiters > 0) 901 cv_broadcast(&srndpool_read_cv); 902 swrand_schedule_timeout(); 903 904 mutex_exit(&srndpool_lock); 905 } 906