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 2010 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 .co_control_ops = &swrand_control_ops,
167 .co_random_ops = &swrand_random_number_ops
168 };
169
170 static crypto_provider_info_t swrand_prov_info = {{{{
171 CRYPTO_SPI_VERSION_4,
172 "Kernel Random Number Provider",
173 CRYPTO_SW_PROVIDER,
174 {&modlinkage},
175 NULL,
176 &swrand_crypto_ops,
177 0,
178 NULL
179 }}}};
180
181 int
182 _init(void)
183 {
184 int ret;
185 hrtime_t ts;
186 time_t now;
187
188 mutex_init(&srndpool_lock, NULL, MUTEX_DEFAULT, NULL);
189 mutex_init(&buffer_lock, NULL, MUTEX_DEFAULT, NULL);
190 cv_init(&srndpool_read_cv, NULL, CV_DEFAULT, NULL);
191 entropy_bits = 0;
192 pindex = 0;
193 bindex = 0;
194 bstart = 0;
195 snum_waiters = 0;
196 leftover_bytes = 0;
197 buffer_bytes = 0;
198
199 /*
200 * Initialize the pool using
201 * . 2 unpredictable times: high resolution time since the boot-time,
202 * and the current time-of-the day.
203 * . The initial physical memory state.
204 */
205 ts = gethrtime();
206 swrand_add_entropy((uint8_t *)&ts, sizeof (ts), 0);
207
208 (void) drv_getparm(TIME, &now);
209 swrand_add_entropy((uint8_t *)&now, sizeof (now), 0);
210
211 ret = kphysm_setup_func_register(&rnd_dr_callback_vec, NULL);
212 ASSERT(ret == 0);
213
214 if (physmem_ent_init(&entsrc) != 0) {
215 ret = ENOMEM;
216 goto exit1;
217 }
218
219 if ((ret = mod_install(&modlinkage)) != 0)
220 goto exit2;
221
222 /* Schedule periodic mixing of the pool. */
223 mutex_enter(&srndpool_lock);
224 swrand_schedule_timeout();
225 mutex_exit(&srndpool_lock);
226 (void) swrand_get_entropy((uint8_t *)swrand_XKEY, HASHSIZE, B_TRUE);
227 bcopy(swrand_XKEY, previous_bytes, HASHSIZE);
228
229 /* Register with KCF. If the registration fails, return error. */
230 if (crypto_register_provider(&swrand_prov_info, &swrand_prov_handle)) {
231 (void) mod_remove(&modlinkage);
232 ret = EACCES;
233 goto exit2;
234 }
235
236 return (0);
237
238 exit2:
239 physmem_ent_fini(&entsrc);
240 exit1:
241 mutex_destroy(&srndpool_lock);
242 mutex_destroy(&buffer_lock);
243 cv_destroy(&srndpool_read_cv);
244 return (ret);
245 }
246
247 int
248 _info(struct modinfo *modinfop)
249 {
250 return (mod_info(&modlinkage, modinfop));
251 }
252
253 /*
254 * Control entry points.
255 */
256 /* ARGSUSED */
257 static void
258 swrand_provider_status(crypto_provider_handle_t provider, uint_t *status)
259 {
260 *status = CRYPTO_PROVIDER_READY;
261 }
262
263 /*
264 * Random number entry points.
265 */
266 /* ARGSUSED */
267 static int
268 swrand_seed_random(crypto_provider_handle_t provider, crypto_session_id_t sid,
269 uchar_t *buf, size_t len, uint_t entropy_est, uint32_t flags,
270 crypto_req_handle_t req)
271 {
272 /* The entropy estimate is always 0 in this path */
273 if (flags & CRYPTO_SEED_NOW)
274 swrand_add_entropy(buf, len, 0);
275 else
276 swrand_add_entropy_later(buf, len);
277 return (CRYPTO_SUCCESS);
278 }
279
280 /* ARGSUSED */
281 static int
282 swrand_generate_random(crypto_provider_handle_t provider,
283 crypto_session_id_t sid, uchar_t *buf, size_t len, crypto_req_handle_t req)
284 {
285 if (crypto_kmflag(req) == KM_NOSLEEP)
286 (void) swrand_get_entropy(buf, len, B_TRUE);
287 else
288 (void) swrand_get_entropy(buf, len, B_FALSE);
289
290 return (CRYPTO_SUCCESS);
291 }
292
293 /*
294 * Extraction of entropy from the pool.
295 *
296 * Returns "len" random bytes in *ptr.
297 * Try to gather some more entropy by calling physmem_ent_gen() when less than
298 * MINEXTRACTBITS are present in the pool.
299 * Will block if not enough entropy was available and the call is blocking.
300 */
301 static int
302 swrand_get_entropy(uint8_t *ptr, size_t len, boolean_t nonblock)
303 {
304 int i, bytes;
305 HASH_CTX hashctx;
306 uint8_t digest[HASHSIZE], *pool;
307 uint32_t tempout[HASHSIZE/BYTES_IN_WORD];
308 int size;
309
310 mutex_enter(&srndpool_lock);
311 if (leftover_bytes > 0) {
312 bytes = min(len, leftover_bytes);
313 bcopy(leftover, ptr, bytes);
314 len -= bytes;
315 ptr += bytes;
316 leftover_bytes -= bytes;
317 if (leftover_bytes > 0)
318 ovbcopy(leftover+bytes, leftover, leftover_bytes);
319 }
320
321 while (len > 0) {
322 /* Check if there is enough entropy */
323 while (entropy_bits < MINEXTRACTBITS) {
324
325 physmem_ent_gen(&entsrc);
326
327 if (entropy_bits < MINEXTRACTBITS &&
328 nonblock == B_TRUE) {
329 mutex_exit(&srndpool_lock);
330 return (EAGAIN);
331 }
332
333 if (entropy_bits < MINEXTRACTBITS) {
334 ASSERT(nonblock == B_FALSE);
335 snum_waiters++;
336 if (cv_wait_sig(&srndpool_read_cv,
337 &srndpool_lock) == 0) {
338 snum_waiters--;
339 mutex_exit(&srndpool_lock);
340 return (EINTR);
341 }
342 snum_waiters--;
343 }
344 }
345
346 /* Figure out how many bytes to extract */
347 bytes = min(HASHSIZE, len);
348 bytes = min(bytes, CRYPTO_BITS2BYTES(entropy_bits));
349 entropy_bits -= CRYPTO_BYTES2BITS(bytes);
350 BUMP_SWRAND_STATS(ss_entOut, CRYPTO_BYTES2BITS(bytes));
351 swrand_stats.ss_entEst = entropy_bits;
352
353 /* Extract entropy by hashing pool content */
354 HashInit(&hashctx);
355 HashUpdate(&hashctx, (uint8_t *)srndpool, RNDPOOLSIZE);
356 HashFinal(digest, &hashctx);
357
358 /*
359 * Feed the digest back into the pool so next
360 * extraction produces different result
361 */
362 pool = (uint8_t *)srndpool;
363 for (i = 0; i < HASHSIZE; i++) {
364 pool[pindex++] ^= digest[i];
365 /* pindex modulo RNDPOOLSIZE */
366 pindex &= (RNDPOOLSIZE - 1);
367 }
368
369 /* LINTED E_BAD_PTR_CAST_ALIGN */
370 fips_random_inner(swrand_XKEY, tempout, (uint32_t *)digest);
371
372 if (len >= HASHSIZE) {
373 size = HASHSIZE;
374 } else {
375 size = min(bytes, HASHSIZE);
376 }
377
378 /*
379 * FIPS 140-2: Continuous RNG test - each generation
380 * of an n-bit block shall be compared with the previously
381 * generated block. Test shall fail if any two compared
382 * n-bit blocks are equal.
383 */
384 for (i = 0; i < HASHSIZE/BYTES_IN_WORD; i++) {
385 if (tempout[i] != previous_bytes[i])
386 break;
387 }
388
389 if (i == HASHSIZE/BYTES_IN_WORD) {
390 cmn_err(CE_WARN, "swrand: The value of 160-bit block "
391 "random bytes are same as the previous one.\n");
392 /* discard random bytes and return error */
393 return (EIO);
394 }
395
396 bcopy(tempout, previous_bytes, HASHSIZE);
397
398 bcopy(tempout, ptr, size);
399 if (len < HASHSIZE) {
400 leftover_bytes = HASHSIZE - bytes;
401 bcopy((uint8_t *)tempout + bytes, leftover,
402 leftover_bytes);
403 }
404
405 ptr += size;
406 len -= size;
407 BUMP_SWRAND_STATS(ss_bytesOut, size);
408 }
409
410 /* Zero out sensitive information */
411 bzero(digest, HASHSIZE);
412 bzero(tempout, HASHSIZE);
413 mutex_exit(&srndpool_lock);
414 return (0);
415 }
416
417 #define SWRAND_ADD_BYTES(ptr, len, i, pool) \
418 ASSERT((ptr) != NULL && (len) > 0); \
419 BUMP_SWRAND_STATS(ss_bytesIn, (len)); \
420 while ((len)--) { \
421 (pool)[(i)++] ^= *(ptr); \
422 (ptr)++; \
423 (i) &= (RNDPOOLSIZE - 1); \
424 }
425
426 /* Write some more user-provided entropy to the pool */
427 static void
428 swrand_add_bytes(uint8_t *ptr, size_t len)
429 {
430 uint8_t *pool = (uint8_t *)srndpool;
431
432 ASSERT(MUTEX_HELD(&srndpool_lock));
433 SWRAND_ADD_BYTES(ptr, len, pindex, pool);
434 }
435
436 /*
437 * Add bytes to buffer. Adding the buffer to the random pool
438 * is deferred until the random pool is mixed.
439 */
440 static void
441 swrand_add_bytes_later(uint8_t *ptr, size_t len)
442 {
443 uint8_t *pool = (uint8_t *)buffer;
444
445 ASSERT(MUTEX_HELD(&buffer_lock));
446 SWRAND_ADD_BYTES(ptr, len, bindex, pool);
447 buffer_bytes += len;
448 }
449
450 #undef SWRAND_ADD_BYTES
451
452 /* Mix the pool */
453 static void
454 swrand_mix_pool(uint16_t entropy_est)
455 {
456 int i, j, k, start;
457 HASH_CTX hashctx;
458 uint8_t digest[HASHSIZE];
459 uint8_t *pool = (uint8_t *)srndpool;
460 uint8_t *bp = (uint8_t *)buffer;
461
462 ASSERT(MUTEX_HELD(&srndpool_lock));
463
464 /* add deferred bytes */
465 mutex_enter(&buffer_lock);
466 if (buffer_bytes > 0) {
467 if (buffer_bytes >= RNDPOOLSIZE) {
468 for (i = 0; i < RNDPOOLSIZE/4; i++) {
469 srndpool[i] ^= buffer[i];
470 buffer[i] = 0;
471 }
472 bstart = bindex = 0;
473 } else {
474 for (i = 0; i < buffer_bytes; i++) {
475 pool[pindex++] ^= bp[bstart];
476 bp[bstart++] = 0;
477 pindex &= (RNDPOOLSIZE - 1);
478 bstart &= (RNDPOOLSIZE - 1);
479 }
480 ASSERT(bstart == bindex);
481 }
482 buffer_bytes = 0;
483 }
484 mutex_exit(&buffer_lock);
485
486 start = 0;
487 for (i = 0; i < RNDPOOLSIZE/HASHSIZE + 1; i++) {
488 HashInit(&hashctx);
489
490 /* Hash a buffer centered on a block in the pool */
491 if (start + HASHBUFSIZE <= RNDPOOLSIZE)
492 HashUpdate(&hashctx, &pool[start], HASHBUFSIZE);
493 else {
494 HashUpdate(&hashctx, &pool[start],
495 RNDPOOLSIZE - start);
496 HashUpdate(&hashctx, pool,
497 HASHBUFSIZE - RNDPOOLSIZE + start);
498 }
499 HashFinal(digest, &hashctx);
500
501 /* XOR the hash result back into the block */
502 k = (start + HASHSIZE) & (RNDPOOLSIZE - 1);
503 for (j = 0; j < HASHSIZE; j++) {
504 pool[k++] ^= digest[j];
505 k &= (RNDPOOLSIZE - 1);
506 }
507
508 /* Slide the hash buffer and repeat with next block */
509 start = (start + HASHSIZE) & (RNDPOOLSIZE - 1);
510 }
511
512 entropy_bits += entropy_est;
513 if (entropy_bits > CRYPTO_BYTES2BITS(RNDPOOLSIZE))
514 entropy_bits = CRYPTO_BYTES2BITS(RNDPOOLSIZE);
515
516 swrand_stats.ss_entEst = entropy_bits;
517 BUMP_SWRAND_STATS(ss_entIn, entropy_est);
518 }
519
520 static void
521 swrand_add_entropy_later(uint8_t *ptr, size_t len)
522 {
523 mutex_enter(&buffer_lock);
524 swrand_add_bytes_later(ptr, len);
525 mutex_exit(&buffer_lock);
526 }
527
528 static void
529 swrand_add_entropy(uint8_t *ptr, size_t len, uint16_t entropy_est)
530 {
531 mutex_enter(&srndpool_lock);
532 swrand_add_bytes(ptr, len);
533 swrand_mix_pool(entropy_est);
534 mutex_exit(&srndpool_lock);
535 }
536
537 /*
538 * The physmem_* routines below generate entropy by reading blocks of
539 * physical memory. Entropy is gathered in a couple of ways:
540 *
541 * - By reading blocks of physical memory and detecting if changes
542 * occurred in the blocks read.
543 *
544 * - By measuring the time it takes to load and hash a block of memory
545 * and computing the differences in the measured time.
546 *
547 * The first method was used in the CryptoRand implementation. Physical
548 * memory is divided into blocks of fixed size. A block of memory is
549 * chosen from the possible blocks and hashed to produce a digest. This
550 * digest is then mixed into the pool. A single bit from the digest is
551 * used as a parity bit or "checksum" and compared against the previous
552 * "checksum" computed for the block. If the single-bit checksum has not
553 * changed, no entropy is credited to the pool. If there is a change,
554 * then the assumption is that at least one bit in the block has changed.
555 * The possible locations within the memory block of where the bit change
556 * occurred is used as a measure of entropy. For example, if a block
557 * size of 4096 bytes is used, about log_2(4096*8)=15 bits worth of
558 * entropy is available. Because the single-bit checksum will miss half
559 * of the changes, the amount of entropy credited to the pool is doubled
560 * when a change is detected. With a 4096 byte block size, a block
561 * change will add a total of 30 bits of entropy to the pool.
562 *
563 * The second method measures the amount of time it takes to read and
564 * hash a physical memory block (as described above). The time measured
565 * can vary depending on system load, scheduling and other factors.
566 * Differences between consecutive measurements are computed to come up
567 * with an entropy estimate. The first, second, and third order delta is
568 * calculated to determine the minimum delta value. The number of bits
569 * present in this minimum delta value is the entropy estimate. This
570 * entropy estimation technique using time deltas is similar to that used
571 * in /dev/random implementations from Linux/BSD.
572 */
573
574 static int
575 physmem_ent_init(physmem_entsrc_t *entsrc)
576 {
577 uint8_t *ptr;
578 int i;
579
580 bzero(entsrc, sizeof (*entsrc));
581
582 /*
583 * The maximum entropy amount in bits per block of memory read is
584 * log_2(MEMBLOCKSIZE * 8);
585 */
586 i = CRYPTO_BYTES2BITS(MEMBLOCKSIZE);
587 while (i >>= 1)
588 entsrc->entperblock++;
589
590 /* Initialize entsrc->nblocks */
591 physmem_count_blocks();
592
593 if (entsrc->nblocks == 0) {
594 cmn_err(CE_WARN, "no memory blocks to scan!");
595 return (-1);
596 }
597
598 /* Allocate space for the parity vector and memory page */
599 entsrc->parity = kmem_alloc(howmany(entsrc->nblocks, 8),
600 KM_SLEEP);
601 entsrc->pmbuf = vmem_alloc(heap_arena, PAGESIZE, VM_SLEEP);
602
603
604 /* Initialize parity vector with bits from the pool */
605 i = howmany(entsrc->nblocks, 8);
606 ptr = entsrc->parity;
607 while (i > 0) {
608 if (i > RNDPOOLSIZE) {
609 bcopy(srndpool, ptr, RNDPOOLSIZE);
610 mutex_enter(&srndpool_lock);
611 swrand_mix_pool(0);
612 mutex_exit(&srndpool_lock);
613 ptr += RNDPOOLSIZE;
614 i -= RNDPOOLSIZE;
615 } else {
616 bcopy(srndpool, ptr, i);
617 break;
618 }
619 }
620
621 /* Generate some entropy to further initialize the pool */
622 mutex_enter(&srndpool_lock);
623 physmem_ent_gen(entsrc);
624 entropy_bits = 0;
625 mutex_exit(&srndpool_lock);
626
627 return (0);
628 }
629
630 static void
631 physmem_ent_fini(physmem_entsrc_t *entsrc)
632 {
633 if (entsrc->pmbuf != NULL)
634 vmem_free(heap_arena, entsrc->pmbuf, PAGESIZE);
635 if (entsrc->parity != NULL)
636 kmem_free(entsrc->parity, howmany(entsrc->nblocks, 8));
637 bzero(entsrc, sizeof (*entsrc));
638 }
639
640 static void
641 physmem_ent_gen(physmem_entsrc_t *entsrc)
642 {
643 struct memlist *pmem;
644 offset_t offset, poffset;
645 pfn_t pfn;
646 int i, nbytes, len, ent = 0;
647 uint32_t block, oblock;
648 hrtime_t ts1, ts2, diff, delta, delta2, delta3;
649 uint8_t digest[HASHSIZE];
650 HASH_CTX ctx;
651 page_t *pp;
652
653 /*
654 * Use each 32-bit quantity in the pool to pick a memory
655 * block to read.
656 */
657 for (i = 0; i < RNDPOOLSIZE/4; i++) {
658
659 /* If the pool is "full", stop after one block */
660 if (entropy_bits + ent >= CRYPTO_BYTES2BITS(RNDPOOLSIZE)) {
661 if (i > 0)
662 break;
663 }
664
665 /*
666 * This lock protects reading of phys_install.
667 * Any changes to this list, by DR, are done while
668 * holding this lock. So, holding this lock is sufficient
669 * to handle DR also.
670 */
671 memlist_read_lock();
672
673 /* We're left with less than 4K of memory after DR */
674 ASSERT(entsrc->nblocks > 0);
675
676 /* Pick a memory block to read */
677 block = oblock = srndpool[i] % entsrc->nblocks;
678
679 for (pmem = phys_install; pmem != NULL; pmem = pmem->ml_next) {
680 if (block < pmem->ml_size / MEMBLOCKSIZE)
681 break;
682 block -= pmem->ml_size / MEMBLOCKSIZE;
683 }
684
685 ASSERT(pmem != NULL);
686
687 offset = pmem->ml_address + block * MEMBLOCKSIZE;
688
689 if (!address_in_memlist(phys_install, offset, MEMBLOCKSIZE)) {
690 memlist_read_unlock();
691 continue;
692 }
693
694 /*
695 * Do an initial check to see if the address is safe
696 */
697 if (plat_hold_page(offset >> PAGESHIFT, PLAT_HOLD_NO_LOCK, NULL)
698 == PLAT_HOLD_FAIL) {
699 memlist_read_unlock();
700 continue;
701 }
702
703 /*
704 * Figure out which page to load to read the
705 * memory block. Load the page and compute the
706 * hash of the memory block.
707 */
708 len = MEMBLOCKSIZE;
709 ts1 = gethrtime();
710 HashInit(&ctx);
711 while (len) {
712 pfn = offset >> PAGESHIFT;
713 poffset = offset & PAGEOFFSET;
714 nbytes = PAGESIZE - poffset < len ?
715 PAGESIZE - poffset : len;
716
717 /*
718 * Re-check the offset, and lock the frame. If the
719 * page was given away after the above check, we'll
720 * just bail out.
721 */
722 if (plat_hold_page(pfn, PLAT_HOLD_LOCK, &pp) ==
723 PLAT_HOLD_FAIL)
724 break;
725
726 hat_devload(kas.a_hat, entsrc->pmbuf,
727 PAGESIZE, pfn, PROT_READ,
728 HAT_LOAD_NOCONSIST | HAT_LOAD_LOCK);
729
730 HashUpdate(&ctx, (uint8_t *)entsrc->pmbuf + poffset,
731 nbytes);
732
733 hat_unload(kas.a_hat, entsrc->pmbuf, PAGESIZE,
734 HAT_UNLOAD_UNLOCK);
735
736 plat_release_page(pp);
737
738 len -= nbytes;
739 offset += nbytes;
740 }
741 /* We got our pages. Let the DR roll */
742 memlist_read_unlock();
743
744 /* See if we had to bail out due to a page being given away */
745 if (len)
746 continue;
747
748 HashFinal(digest, &ctx);
749 ts2 = gethrtime();
750
751 /*
752 * Compute the time it took to load and hash the
753 * block and compare it against the previous
754 * measurement. The delta of the time values
755 * provides a small amount of entropy. The
756 * minimum of the first, second, and third order
757 * delta is used to estimate how much entropy
758 * is present.
759 */
760 diff = ts2 - ts1;
761 delta = diff - entsrc->last_diff;
762 if (delta < 0)
763 delta = -delta;
764 delta2 = delta - entsrc->last_delta;
765 if (delta2 < 0)
766 delta2 = -delta2;
767 delta3 = delta2 - entsrc->last_delta2;
768 if (delta3 < 0)
769 delta3 = -delta3;
770 entsrc->last_diff = diff;
771 entsrc->last_delta = delta;
772 entsrc->last_delta2 = delta2;
773
774 if (delta > delta2)
775 delta = delta2;
776 if (delta > delta3)
777 delta = delta3;
778 delta2 = 0;
779 while (delta >>= 1)
780 delta2++;
781 ent += delta2;
782
783 /*
784 * If the memory block has changed, credit the pool with
785 * the entropy estimate. The entropy estimate is doubled
786 * because the single-bit checksum misses half the change
787 * on average.
788 */
789 if (physmem_parity_update(entsrc->parity, oblock,
790 digest[0] & 1))
791 ent += 2 * entsrc->entperblock;
792
793 /* Add the entropy bytes to the pool */
794 swrand_add_bytes(digest, HASHSIZE);
795 swrand_add_bytes((uint8_t *)&ts1, sizeof (ts1));
796 swrand_add_bytes((uint8_t *)&ts2, sizeof (ts2));
797 }
798
799 swrand_mix_pool(ent);
800 }
801
802 static int
803 physmem_parity_update(uint8_t *parity_vec, uint32_t block, int parity)
804 {
805 /* Test and set the parity bit, return 1 if changed */
806 if (parity == ((parity_vec[block >> 3] >> (block & 7)) & 1))
807 return (0);
808 parity_vec[block >> 3] ^= 1 << (block & 7);
809 return (1);
810 }
811
812 /* Compute number of memory blocks available to scan */
813 static void
814 physmem_count_blocks()
815 {
816 struct memlist *pmem;
817
818 memlist_read_lock();
819 entsrc.nblocks = 0;
820 for (pmem = phys_install; pmem != NULL; pmem = pmem->ml_next) {
821 entsrc.nblocks += pmem->ml_size / MEMBLOCKSIZE;
822 if (entsrc.nblocks > MAXMEMBLOCKS) {
823 entsrc.nblocks = MAXMEMBLOCKS;
824 break;
825 }
826 }
827 memlist_read_unlock();
828 }
829
830 /*
831 * Dynamic Reconfiguration call-back functions
832 */
833
834 /* ARGSUSED */
835 static void
836 rnd_dr_callback_post_add(void *arg, pgcnt_t delta)
837 {
838 /* More memory is available now, so update entsrc->nblocks. */
839 physmem_count_blocks();
840 }
841
842 /* Call-back routine invoked before the DR starts a memory removal. */
843 /* ARGSUSED */
844 static int
845 rnd_dr_callback_pre_del(void *arg, pgcnt_t delta)
846 {
847 return (0);
848 }
849
850 /* Call-back routine invoked after the DR starts a memory removal. */
851 /* ARGSUSED */
852 static void
853 rnd_dr_callback_post_del(void *arg, pgcnt_t delta, int cancelled)
854 {
855 /* Memory has shrunk, so update entsrc->nblocks. */
856 physmem_count_blocks();
857 }
858
859 /* Timeout handling to gather entropy from physmem events */
860 static void
861 swrand_schedule_timeout(void)
862 {
863 clock_t ut; /* time in microseconds */
864
865 ASSERT(MUTEX_HELD(&srndpool_lock));
866 /*
867 * The new timeout value is taken from the pool of random bits.
868 * We're merely reading the first 32 bits from the pool here, not
869 * consuming any entropy.
870 * This routine is usually called right after stirring the pool, so
871 * srndpool[0] will have a *fresh* random value each time.
872 * The timeout multiplier value is a random value between 0.7 sec and
873 * 1.748575 sec (0.7 sec + 0xFFFFF microseconds).
874 * The new timeout is TIMEOUT_INTERVAL times that multiplier.
875 */
876 ut = 700000 + (clock_t)(srndpool[0] & 0xFFFFF);
877 rnd_timeout_id = timeout(rnd_handler, NULL,
878 TIMEOUT_INTERVAL * drv_usectohz(ut));
879 }
880
881 /*ARGSUSED*/
882 static void
883 rnd_handler(void *arg)
884 {
885 mutex_enter(&srndpool_lock);
886
887 physmem_ent_gen(&entsrc);
888 if (snum_waiters > 0)
889 cv_broadcast(&srndpool_read_cv);
890 swrand_schedule_timeout();
891
892 mutex_exit(&srndpool_lock);
893 }