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((uint8_t *)tempout + bytes, leftover, 415 leftover_bytes); 416 } 417 418 ptr += size; 419 len -= size; 420 BUMP_SWRAND_STATS(ss_bytesOut, size); 421 } 422 423 /* Zero out sensitive information */ 424 bzero(digest, HASHSIZE); 425 bzero(tempout, HASHSIZE); 426 mutex_exit(&srndpool_lock); 427 return (0); 428 } 429 430 #define SWRAND_ADD_BYTES(ptr, len, i, pool) \ 431 ASSERT((ptr) != NULL && (len) > 0); \ 432 BUMP_SWRAND_STATS(ss_bytesIn, (len)); \ 433 while ((len)--) { \ 434 (pool)[(i)++] ^= *(ptr); \ 435 (ptr)++; \ 436 (i) &= (RNDPOOLSIZE - 1); \ 437 } 438 439 /* Write some more user-provided entropy to the pool */ 440 static void 441 swrand_add_bytes(uint8_t *ptr, size_t len) 442 { 443 uint8_t *pool = (uint8_t *)srndpool; 444 445 ASSERT(MUTEX_HELD(&srndpool_lock)); 446 SWRAND_ADD_BYTES(ptr, len, pindex, pool); 447 } 448 449 /* 450 * Add bytes to buffer. Adding the buffer to the random pool 451 * is deferred until the random pool is mixed. 452 */ 453 static void 454 swrand_add_bytes_later(uint8_t *ptr, size_t len) 455 { 456 uint8_t *pool = (uint8_t *)buffer; 457 458 ASSERT(MUTEX_HELD(&buffer_lock)); 459 SWRAND_ADD_BYTES(ptr, len, bindex, pool); 460 buffer_bytes += len; 461 } 462 463 #undef SWRAND_ADD_BYTES 464 465 /* Mix the pool */ 466 static void 467 swrand_mix_pool(uint16_t entropy_est) 468 { 469 int i, j, k, start; 470 HASH_CTX hashctx; 471 uint8_t digest[HASHSIZE]; 472 uint8_t *pool = (uint8_t *)srndpool; 473 uint8_t *bp = (uint8_t *)buffer; 474 475 ASSERT(MUTEX_HELD(&srndpool_lock)); 476 477 /* add deferred bytes */ 478 mutex_enter(&buffer_lock); 479 if (buffer_bytes > 0) { 480 if (buffer_bytes >= RNDPOOLSIZE) { 481 for (i = 0; i < RNDPOOLSIZE/4; i++) { 482 srndpool[i] ^= buffer[i]; 483 buffer[i] = 0; 484 } 485 bstart = bindex = 0; 486 } else { 487 for (i = 0; i < buffer_bytes; i++) { 488 pool[pindex++] ^= bp[bstart]; 489 bp[bstart++] = 0; 490 pindex &= (RNDPOOLSIZE - 1); 491 bstart &= (RNDPOOLSIZE - 1); 492 } 493 ASSERT(bstart == bindex); 494 } 495 buffer_bytes = 0; 496 } 497 mutex_exit(&buffer_lock); 498 499 start = 0; 500 for (i = 0; i < RNDPOOLSIZE/HASHSIZE + 1; i++) { 501 HashInit(&hashctx); 502 503 /* Hash a buffer centered on a block in the pool */ 504 if (start + HASHBUFSIZE <= RNDPOOLSIZE) 505 HashUpdate(&hashctx, &pool[start], HASHBUFSIZE); 506 else { 507 HashUpdate(&hashctx, &pool[start], 508 RNDPOOLSIZE - start); 509 HashUpdate(&hashctx, pool, 510 HASHBUFSIZE - RNDPOOLSIZE + start); 511 } 512 HashFinal(digest, &hashctx); 513 514 /* XOR the hash result back into the block */ 515 k = (start + HASHSIZE) & (RNDPOOLSIZE - 1); 516 for (j = 0; j < HASHSIZE; j++) { 517 pool[k++] ^= digest[j]; 518 k &= (RNDPOOLSIZE - 1); 519 } 520 521 /* Slide the hash buffer and repeat with next block */ 522 start = (start + HASHSIZE) & (RNDPOOLSIZE - 1); 523 } 524 525 entropy_bits += entropy_est; 526 if (entropy_bits > RNDPOOLSIZE * 8) 527 entropy_bits = RNDPOOLSIZE * 8; 528 529 swrand_stats.ss_entEst = entropy_bits; 530 BUMP_SWRAND_STATS(ss_entIn, entropy_est); 531 } 532 533 static void 534 swrand_add_entropy_later(uint8_t *ptr, size_t len) 535 { 536 mutex_enter(&buffer_lock); 537 swrand_add_bytes_later(ptr, len); 538 mutex_exit(&buffer_lock); 539 } 540 541 static void 542 swrand_add_entropy(uint8_t *ptr, size_t len, uint16_t entropy_est) 543 { 544 mutex_enter(&srndpool_lock); 545 swrand_add_bytes(ptr, len); 546 swrand_mix_pool(entropy_est); 547 mutex_exit(&srndpool_lock); 548 } 549 550 /* 551 * The physmem_* routines below generate entropy by reading blocks of 552 * physical memory. Entropy is gathered in a couple of ways: 553 * 554 * - By reading blocks of physical memory and detecting if changes 555 * occurred in the blocks read. 556 * 557 * - By measuring the time it takes to load and hash a block of memory 558 * and computing the differences in the measured time. 559 * 560 * The first method was used in the CryptoRand implementation. Physical 561 * memory is divided into blocks of fixed size. A block of memory is 562 * chosen from the possible blocks and hashed to produce a digest. This 563 * digest is then mixed into the pool. A single bit from the digest is 564 * used as a parity bit or "checksum" and compared against the previous 565 * "checksum" computed for the block. If the single-bit checksum has not 566 * changed, no entropy is credited to the pool. If there is a change, 567 * then the assumption is that at least one bit in the block has changed. 568 * The possible locations within the memory block of where the bit change 569 * occurred is used as a measure of entropy. For example, if a block 570 * size of 4096 bytes is used, about log_2(4096*8)=15 bits worth of 571 * entropy is available. Because the single-bit checksum will miss half 572 * of the changes, the amount of entropy credited to the pool is doubled 573 * when a change is detected. With a 4096 byte block size, a block 574 * change will add a total of 30 bits of entropy to the pool. 575 * 576 * The second method measures the amount of time it takes to read and 577 * hash a physical memory block (as described above). The time measured 578 * can vary depending on system load, scheduling and other factors. 579 * Differences between consecutive measurements are computed to come up 580 * with an entropy estimate. The first, second, and third order delta is 581 * calculated to determine the minimum delta value. The number of bits 582 * present in this minimum delta value is the entropy estimate. This 583 * entropy estimation technique using time deltas is similar to that used 584 * in /dev/random implementations from Linux/BSD. 585 */ 586 587 static int 588 physmem_ent_init(physmem_entsrc_t *entsrc) 589 { 590 uint8_t *ptr; 591 int i; 592 593 bzero(entsrc, sizeof (*entsrc)); 594 595 /* 596 * The maximum entropy amount in bits per block of memory read is 597 * log_2(MEMBLOCKSIZE * 8); 598 */ 599 i = MEMBLOCKSIZE << 3; 600 while (i >>= 1) 601 entsrc->entperblock++; 602 603 /* Initialize entsrc->nblocks */ 604 physmem_count_blocks(); 605 606 if (entsrc->nblocks == 0) { 607 cmn_err(CE_WARN, "no memory blocks to scan!"); 608 return (-1); 609 } 610 611 /* Allocate space for the parity vector and memory page */ 612 entsrc->parity = kmem_alloc(howmany(entsrc->nblocks, 8), 613 KM_SLEEP); 614 entsrc->pmbuf = vmem_alloc(heap_arena, PAGESIZE, VM_SLEEP); 615 616 617 /* Initialize parity vector with bits from the pool */ 618 i = howmany(entsrc->nblocks, 8); 619 ptr = entsrc->parity; 620 while (i > 0) { 621 if (i > RNDPOOLSIZE) { 622 bcopy(srndpool, ptr, RNDPOOLSIZE); 623 mutex_enter(&srndpool_lock); 624 swrand_mix_pool(0); 625 mutex_exit(&srndpool_lock); 626 ptr += RNDPOOLSIZE; 627 i -= RNDPOOLSIZE; 628 } else { 629 bcopy(srndpool, ptr, i); 630 break; 631 } 632 } 633 634 /* Generate some entropy to further initialize the pool */ 635 mutex_enter(&srndpool_lock); 636 physmem_ent_gen(entsrc); 637 entropy_bits = 0; 638 mutex_exit(&srndpool_lock); 639 640 return (0); 641 } 642 643 static void 644 physmem_ent_fini(physmem_entsrc_t *entsrc) 645 { 646 if (entsrc->pmbuf != NULL) 647 vmem_free(heap_arena, entsrc->pmbuf, PAGESIZE); 648 if (entsrc->parity != NULL) 649 kmem_free(entsrc->parity, howmany(entsrc->nblocks, 8)); 650 bzero(entsrc, sizeof (*entsrc)); 651 } 652 653 static void 654 physmem_ent_gen(physmem_entsrc_t *entsrc) 655 { 656 struct memlist *pmem; 657 offset_t offset, poffset; 658 pfn_t pfn; 659 int i, nbytes, len, ent = 0; 660 uint32_t block, oblock; 661 hrtime_t ts1, ts2, diff, delta, delta2, delta3; 662 uint8_t digest[HASHSIZE]; 663 HASH_CTX ctx; 664 page_t *pp; 665 666 /* 667 * Use each 32-bit quantity in the pool to pick a memory 668 * block to read. 669 */ 670 for (i = 0; i < RNDPOOLSIZE/4; i++) { 671 672 /* If the pool is "full", stop after one block */ 673 if (entropy_bits + ent >= RNDPOOLSIZE * 8) { 674 if (i > 0) 675 break; 676 } 677 678 /* 679 * This lock protects reading of phys_install. 680 * Any changes to this list, by DR, are done while 681 * holding this lock. So, holding this lock is sufficient 682 * to handle DR also. 683 */ 684 memlist_read_lock(); 685 686 /* We're left with less than 4K of memory after DR */ 687 ASSERT(entsrc->nblocks > 0); 688 689 /* Pick a memory block to read */ 690 block = oblock = srndpool[i] % entsrc->nblocks; 691 692 for (pmem = phys_install; pmem != NULL; pmem = pmem->next) { 693 if (block < pmem->size / MEMBLOCKSIZE) 694 break; 695 block -= pmem->size / MEMBLOCKSIZE; 696 } 697 698 ASSERT(pmem != NULL); 699 700 offset = pmem->address + block * MEMBLOCKSIZE; 701 702 if (!address_in_memlist(phys_install, offset, MEMBLOCKSIZE)) { 703 memlist_read_unlock(); 704 continue; 705 } 706 707 /* 708 * Do an initial check to see if the address is safe 709 */ 710 if (plat_hold_page(offset >> PAGESHIFT, PLAT_HOLD_NO_LOCK, NULL) 711 == PLAT_HOLD_FAIL) { 712 memlist_read_unlock(); 713 continue; 714 } 715 716 /* 717 * Figure out which page to load to read the 718 * memory block. Load the page and compute the 719 * hash of the memory block. 720 */ 721 len = MEMBLOCKSIZE; 722 ts1 = gethrtime(); 723 HashInit(&ctx); 724 while (len) { 725 pfn = offset >> PAGESHIFT; 726 poffset = offset & PAGEOFFSET; 727 nbytes = PAGESIZE - poffset < len ? 728 PAGESIZE - poffset : len; 729 730 /* 731 * Re-check the offset, and lock the frame. If the 732 * page was given away after the above check, we'll 733 * just bail out. 734 */ 735 if (plat_hold_page(pfn, PLAT_HOLD_LOCK, &pp) == 736 PLAT_HOLD_FAIL) 737 break; 738 739 hat_devload(kas.a_hat, entsrc->pmbuf, 740 PAGESIZE, pfn, PROT_READ, 741 HAT_LOAD_NOCONSIST | HAT_LOAD_LOCK); 742 743 HashUpdate(&ctx, (uint8_t *)entsrc->pmbuf + poffset, 744 nbytes); 745 746 hat_unload(kas.a_hat, entsrc->pmbuf, PAGESIZE, 747 HAT_UNLOAD_UNLOCK); 748 749 plat_release_page(pp); 750 751 len -= nbytes; 752 offset += nbytes; 753 } 754 /* We got our pages. Let the DR roll */ 755 memlist_read_unlock(); 756 757 /* See if we had to bail out due to a page being given away */ 758 if (len) 759 continue; 760 761 HashFinal(digest, &ctx); 762 ts2 = gethrtime(); 763 764 /* 765 * Compute the time it took to load and hash the 766 * block and compare it against the previous 767 * measurement. The delta of the time values 768 * provides a small amount of entropy. The 769 * minimum of the first, second, and third order 770 * delta is used to estimate how much entropy 771 * is present. 772 */ 773 diff = ts2 - ts1; 774 delta = diff - entsrc->last_diff; 775 if (delta < 0) 776 delta = -delta; 777 delta2 = delta - entsrc->last_delta; 778 if (delta2 < 0) 779 delta2 = -delta2; 780 delta3 = delta2 - entsrc->last_delta2; 781 if (delta3 < 0) 782 delta3 = -delta3; 783 entsrc->last_diff = diff; 784 entsrc->last_delta = delta; 785 entsrc->last_delta2 = delta2; 786 787 if (delta > delta2) 788 delta = delta2; 789 if (delta > delta3) 790 delta = delta3; 791 delta2 = 0; 792 while (delta >>= 1) 793 delta2++; 794 ent += delta2; 795 796 /* 797 * If the memory block has changed, credit the pool with 798 * the entropy estimate. The entropy estimate is doubled 799 * because the single-bit checksum misses half the change 800 * on average. 801 */ 802 if (physmem_parity_update(entsrc->parity, oblock, 803 digest[0] & 1)) 804 ent += 2 * entsrc->entperblock; 805 806 /* Add the entropy bytes to the pool */ 807 swrand_add_bytes(digest, HASHSIZE); 808 swrand_add_bytes((uint8_t *)&ts1, sizeof (ts1)); 809 swrand_add_bytes((uint8_t *)&ts2, sizeof (ts2)); 810 } 811 812 swrand_mix_pool(ent); 813 } 814 815 static int 816 physmem_parity_update(uint8_t *parity_vec, uint32_t block, int parity) 817 { 818 /* Test and set the parity bit, return 1 if changed */ 819 if (parity == ((parity_vec[block >> 3] >> (block & 7)) & 1)) 820 return (0); 821 parity_vec[block >> 3] ^= 1 << (block & 7); 822 return (1); 823 } 824 825 /* Compute number of memory blocks available to scan */ 826 static void 827 physmem_count_blocks() 828 { 829 struct memlist *pmem; 830 831 memlist_read_lock(); 832 entsrc.nblocks = 0; 833 for (pmem = phys_install; pmem != NULL; pmem = pmem->next) { 834 entsrc.nblocks += pmem->size / MEMBLOCKSIZE; 835 if (entsrc.nblocks > MAXMEMBLOCKS) { 836 entsrc.nblocks = MAXMEMBLOCKS; 837 break; 838 } 839 } 840 memlist_read_unlock(); 841 } 842 843 /* 844 * Dynamic Reconfiguration call-back functions 845 */ 846 847 /* ARGSUSED */ 848 static void 849 rnd_dr_callback_post_add(void *arg, pgcnt_t delta) 850 { 851 /* More memory is available now, so update entsrc->nblocks. */ 852 physmem_count_blocks(); 853 } 854 855 /* Call-back routine invoked before the DR starts a memory removal. */ 856 /* ARGSUSED */ 857 static int 858 rnd_dr_callback_pre_del(void *arg, pgcnt_t delta) 859 { 860 return (0); 861 } 862 863 /* Call-back routine invoked after the DR starts a memory removal. */ 864 /* ARGSUSED */ 865 static void 866 rnd_dr_callback_post_del(void *arg, pgcnt_t delta, int cancelled) 867 { 868 /* Memory has shrunk, so update entsrc->nblocks. */ 869 physmem_count_blocks(); 870 } 871 872 /* Timeout handling to gather entropy from physmem events */ 873 static void 874 swrand_schedule_timeout(void) 875 { 876 clock_t ut; /* time in microseconds */ 877 878 ASSERT(MUTEX_HELD(&srndpool_lock)); 879 /* 880 * The new timeout value is taken from the pool of random bits. 881 * We're merely reading the first 32 bits from the pool here, not 882 * consuming any entropy. 883 * This routine is usually called right after stirring the pool, so 884 * srndpool[0] will have a *fresh* random value each time. 885 * The timeout multiplier value is a random value between 0.7 sec and 886 * 1.748575 sec (0.7 sec + 0xFFFFF microseconds). 887 * The new timeout is TIMEOUT_INTERVAL times that multiplier. 888 */ 889 ut = 700000 + (clock_t)(srndpool[0] & 0xFFFFF); 890 rnd_timeout_id = timeout(rnd_handler, NULL, 891 TIMEOUT_INTERVAL * drv_usectohz(ut)); 892 } 893 894 /*ARGSUSED*/ 895 static void 896 rnd_handler(void *arg) 897 { 898 mutex_enter(&srndpool_lock); 899 900 physmem_ent_gen(&entsrc); 901 if (snum_waiters > 0) 902 cv_broadcast(&srndpool_read_cv); 903 swrand_schedule_timeout(); 904 905 mutex_exit(&srndpool_lock); 906 } 907