xref: /titanic_41/usr/src/uts/common/crypto/io/swrand.c (revision 6ea3c0609e50782557505b88bb391b786bca32c9)
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 	&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 	NULL,
181 	NULL,
182 	NULL,
183 };
184 
185 static crypto_provider_info_t swrand_prov_info = {
186 	CRYPTO_SPI_VERSION_4,
187 	"Kernel Random Number Provider",
188 	CRYPTO_SW_PROVIDER,
189 	{&modlinkage},
190 	NULL,
191 	&swrand_crypto_ops,
192 	0,
193 	NULL
194 };
195 
196 int
_init(void)197 _init(void)
198 {
199 	int ret;
200 	hrtime_t ts;
201 	time_t now;
202 
203 	mutex_init(&srndpool_lock, NULL, MUTEX_DEFAULT, NULL);
204 	mutex_init(&buffer_lock, NULL, MUTEX_DEFAULT, NULL);
205 	cv_init(&srndpool_read_cv, NULL, CV_DEFAULT, NULL);
206 	entropy_bits = 0;
207 	pindex = 0;
208 	bindex = 0;
209 	bstart = 0;
210 	snum_waiters = 0;
211 	leftover_bytes = 0;
212 	buffer_bytes = 0;
213 
214 	/*
215 	 * Initialize the pool using
216 	 * . 2 unpredictable times: high resolution time since the boot-time,
217 	 *   and the current time-of-the day.
218 	 * . The initial physical memory state.
219 	 */
220 	ts = gethrtime();
221 	swrand_add_entropy((uint8_t *)&ts, sizeof (ts), 0);
222 
223 	(void) drv_getparm(TIME, &now);
224 	swrand_add_entropy((uint8_t *)&now, sizeof (now), 0);
225 
226 	ret = kphysm_setup_func_register(&rnd_dr_callback_vec, NULL);
227 	ASSERT(ret == 0);
228 
229 	if (physmem_ent_init(&entsrc) != 0) {
230 		ret = ENOMEM;
231 		goto exit1;
232 	}
233 
234 	if ((ret = mod_install(&modlinkage)) != 0)
235 		goto exit2;
236 
237 	/* Schedule periodic mixing of the pool. */
238 	mutex_enter(&srndpool_lock);
239 	swrand_schedule_timeout();
240 	mutex_exit(&srndpool_lock);
241 	(void) swrand_get_entropy((uint8_t *)swrand_XKEY, HASHSIZE, B_TRUE);
242 	bcopy(swrand_XKEY, previous_bytes, HASHSIZE);
243 
244 	/* Register with KCF. If the registration fails, return error. */
245 	if (crypto_register_provider(&swrand_prov_info, &swrand_prov_handle)) {
246 		(void) mod_remove(&modlinkage);
247 		ret = EACCES;
248 		goto exit2;
249 	}
250 
251 	return (0);
252 
253 exit2:
254 	physmem_ent_fini(&entsrc);
255 exit1:
256 	mutex_destroy(&srndpool_lock);
257 	mutex_destroy(&buffer_lock);
258 	cv_destroy(&srndpool_read_cv);
259 	return (ret);
260 }
261 
262 int
_info(struct modinfo * modinfop)263 _info(struct modinfo *modinfop)
264 {
265 	return (mod_info(&modlinkage, modinfop));
266 }
267 
268 /*
269  * Control entry points.
270  */
271 /* ARGSUSED */
272 static void
swrand_provider_status(crypto_provider_handle_t provider,uint_t * status)273 swrand_provider_status(crypto_provider_handle_t provider, uint_t *status)
274 {
275 	*status = CRYPTO_PROVIDER_READY;
276 }
277 
278 /*
279  * Random number entry points.
280  */
281 /* ARGSUSED */
282 static int
swrand_seed_random(crypto_provider_handle_t provider,crypto_session_id_t sid,uchar_t * buf,size_t len,uint_t entropy_est,uint32_t flags,crypto_req_handle_t req)283 swrand_seed_random(crypto_provider_handle_t provider, crypto_session_id_t sid,
284     uchar_t *buf, size_t len, uint_t entropy_est, uint32_t flags,
285     crypto_req_handle_t req)
286 {
287 	/* The entropy estimate is always 0 in this path */
288 	if (flags & CRYPTO_SEED_NOW)
289 		swrand_add_entropy(buf, len, 0);
290 	else
291 		swrand_add_entropy_later(buf, len);
292 	return (CRYPTO_SUCCESS);
293 }
294 
295 /* ARGSUSED */
296 static int
swrand_generate_random(crypto_provider_handle_t provider,crypto_session_id_t sid,uchar_t * buf,size_t len,crypto_req_handle_t req)297 swrand_generate_random(crypto_provider_handle_t provider,
298     crypto_session_id_t sid, uchar_t *buf, size_t len, crypto_req_handle_t req)
299 {
300 	if (crypto_kmflag(req) == KM_NOSLEEP)
301 		(void) swrand_get_entropy(buf, len, B_TRUE);
302 	else
303 		(void) swrand_get_entropy(buf, len, B_FALSE);
304 
305 	return (CRYPTO_SUCCESS);
306 }
307 
308 /*
309  * Extraction of entropy from the pool.
310  *
311  * Returns "len" random bytes in *ptr.
312  * Try to gather some more entropy by calling physmem_ent_gen() when less than
313  * MINEXTRACTBITS are present in the pool.
314  * Will block if not enough entropy was available and the call is blocking.
315  */
316 static int
swrand_get_entropy(uint8_t * ptr,size_t len,boolean_t nonblock)317 swrand_get_entropy(uint8_t *ptr, size_t len, boolean_t nonblock)
318 {
319 	int i, bytes;
320 	HASH_CTX hashctx;
321 	uint8_t digest[HASHSIZE], *pool;
322 	uint32_t tempout[HASHSIZE/BYTES_IN_WORD];
323 	int size;
324 
325 	mutex_enter(&srndpool_lock);
326 	if (leftover_bytes > 0) {
327 		bytes = min(len, leftover_bytes);
328 		bcopy(leftover, ptr, bytes);
329 		len -= bytes;
330 		ptr += bytes;
331 		leftover_bytes -= bytes;
332 		if (leftover_bytes > 0)
333 			ovbcopy(leftover+bytes, leftover, leftover_bytes);
334 	}
335 
336 	while (len > 0) {
337 		/* Check if there is enough entropy */
338 		while (entropy_bits < MINEXTRACTBITS) {
339 
340 			physmem_ent_gen(&entsrc);
341 
342 			if (entropy_bits < MINEXTRACTBITS &&
343 			    nonblock == B_TRUE) {
344 				mutex_exit(&srndpool_lock);
345 				return (EAGAIN);
346 			}
347 
348 			if (entropy_bits < MINEXTRACTBITS) {
349 				ASSERT(nonblock == B_FALSE);
350 				snum_waiters++;
351 				if (cv_wait_sig(&srndpool_read_cv,
352 				    &srndpool_lock) == 0) {
353 					snum_waiters--;
354 					mutex_exit(&srndpool_lock);
355 					return (EINTR);
356 				}
357 				snum_waiters--;
358 			}
359 		}
360 
361 		/* Figure out how many bytes to extract */
362 		bytes = min(HASHSIZE, len);
363 		bytes = min(bytes, CRYPTO_BITS2BYTES(entropy_bits));
364 		entropy_bits -= CRYPTO_BYTES2BITS(bytes);
365 		BUMP_SWRAND_STATS(ss_entOut, CRYPTO_BYTES2BITS(bytes));
366 		swrand_stats.ss_entEst = entropy_bits;
367 
368 		/* Extract entropy by hashing pool content */
369 		HashInit(&hashctx);
370 		HashUpdate(&hashctx, (uint8_t *)srndpool, RNDPOOLSIZE);
371 		HashFinal(digest, &hashctx);
372 
373 		/*
374 		 * Feed the digest back into the pool so next
375 		 * extraction produces different result
376 		 */
377 		pool = (uint8_t *)srndpool;
378 		for (i = 0; i < HASHSIZE; i++) {
379 			pool[pindex++] ^= digest[i];
380 			/* pindex modulo RNDPOOLSIZE */
381 			pindex &= (RNDPOOLSIZE - 1);
382 		}
383 
384 		/* LINTED E_BAD_PTR_CAST_ALIGN */
385 		fips_random_inner(swrand_XKEY, tempout, (uint32_t *)digest);
386 
387 		if (len >= HASHSIZE) {
388 			size = HASHSIZE;
389 		} else {
390 			size = min(bytes, HASHSIZE);
391 		}
392 
393 		/*
394 		 * FIPS 140-2: Continuous RNG test - each generation
395 		 * of an n-bit block shall be compared with the previously
396 		 * generated block. Test shall fail if any two compared
397 		 * n-bit blocks are equal.
398 		 */
399 		for (i = 0; i < HASHSIZE/BYTES_IN_WORD; i++) {
400 			if (tempout[i] != previous_bytes[i])
401 				break;
402 		}
403 
404 		if (i == HASHSIZE/BYTES_IN_WORD) {
405 			cmn_err(CE_WARN, "swrand: The value of 160-bit block "
406 			    "random bytes are same as the previous one.\n");
407 			/* discard random bytes and return error */
408 			return (EIO);
409 		}
410 
411 		bcopy(tempout, previous_bytes, HASHSIZE);
412 
413 		bcopy(tempout, ptr, size);
414 		if (len < HASHSIZE) {
415 			leftover_bytes = HASHSIZE - bytes;
416 			bcopy((uint8_t *)tempout + bytes, leftover,
417 			    leftover_bytes);
418 		}
419 
420 		ptr += size;
421 		len -= size;
422 		BUMP_SWRAND_STATS(ss_bytesOut, size);
423 	}
424 
425 	/* Zero out sensitive information */
426 	bzero(digest, HASHSIZE);
427 	bzero(tempout, HASHSIZE);
428 	mutex_exit(&srndpool_lock);
429 	return (0);
430 }
431 
432 #define	SWRAND_ADD_BYTES(ptr, len, i, pool)		\
433 	ASSERT((ptr) != NULL && (len) > 0);		\
434 	BUMP_SWRAND_STATS(ss_bytesIn, (len));		\
435 	while ((len)--) {				\
436 		(pool)[(i)++] ^= *(ptr);		\
437 		(ptr)++;				\
438 		(i) &= (RNDPOOLSIZE - 1);		\
439 	}
440 
441 /* Write some more user-provided entropy to the pool */
442 static void
swrand_add_bytes(uint8_t * ptr,size_t len)443 swrand_add_bytes(uint8_t *ptr, size_t len)
444 {
445 	uint8_t *pool = (uint8_t *)srndpool;
446 
447 	ASSERT(MUTEX_HELD(&srndpool_lock));
448 	SWRAND_ADD_BYTES(ptr, len, pindex, pool);
449 }
450 
451 /*
452  * Add bytes to buffer. Adding the buffer to the random pool
453  * is deferred until the random pool is mixed.
454  */
455 static void
swrand_add_bytes_later(uint8_t * ptr,size_t len)456 swrand_add_bytes_later(uint8_t *ptr, size_t len)
457 {
458 	uint8_t *pool = (uint8_t *)buffer;
459 
460 	ASSERT(MUTEX_HELD(&buffer_lock));
461 	SWRAND_ADD_BYTES(ptr, len, bindex, pool);
462 	buffer_bytes += len;
463 }
464 
465 #undef SWRAND_ADD_BYTES
466 
467 /* Mix the pool */
468 static void
swrand_mix_pool(uint16_t entropy_est)469 swrand_mix_pool(uint16_t entropy_est)
470 {
471 	int i, j, k, start;
472 	HASH_CTX hashctx;
473 	uint8_t digest[HASHSIZE];
474 	uint8_t *pool = (uint8_t *)srndpool;
475 	uint8_t *bp = (uint8_t *)buffer;
476 
477 	ASSERT(MUTEX_HELD(&srndpool_lock));
478 
479 	/* add deferred bytes */
480 	mutex_enter(&buffer_lock);
481 	if (buffer_bytes > 0) {
482 		if (buffer_bytes >= RNDPOOLSIZE) {
483 			for (i = 0; i < RNDPOOLSIZE/4; i++) {
484 				srndpool[i] ^= buffer[i];
485 				buffer[i] = 0;
486 			}
487 			bstart = bindex = 0;
488 		} else {
489 			for (i = 0; i < buffer_bytes; i++) {
490 				pool[pindex++] ^= bp[bstart];
491 				bp[bstart++] = 0;
492 				pindex &= (RNDPOOLSIZE - 1);
493 				bstart &= (RNDPOOLSIZE - 1);
494 			}
495 			ASSERT(bstart == bindex);
496 		}
497 		buffer_bytes = 0;
498 	}
499 	mutex_exit(&buffer_lock);
500 
501 	start = 0;
502 	for (i = 0; i < RNDPOOLSIZE/HASHSIZE + 1; i++) {
503 		HashInit(&hashctx);
504 
505 		/* Hash a buffer centered on a block in the pool */
506 		if (start + HASHBUFSIZE <= RNDPOOLSIZE)
507 			HashUpdate(&hashctx, &pool[start], HASHBUFSIZE);
508 		else {
509 			HashUpdate(&hashctx, &pool[start],
510 			    RNDPOOLSIZE - start);
511 			HashUpdate(&hashctx, pool,
512 			    HASHBUFSIZE - RNDPOOLSIZE + start);
513 		}
514 		HashFinal(digest, &hashctx);
515 
516 		/* XOR the hash result back into the block */
517 		k = (start + HASHSIZE) & (RNDPOOLSIZE - 1);
518 		for (j = 0; j < HASHSIZE; j++) {
519 			pool[k++] ^= digest[j];
520 			k &= (RNDPOOLSIZE - 1);
521 		}
522 
523 		/* Slide the hash buffer and repeat with next block */
524 		start = (start + HASHSIZE) & (RNDPOOLSIZE - 1);
525 	}
526 
527 	entropy_bits += entropy_est;
528 	if (entropy_bits > CRYPTO_BYTES2BITS(RNDPOOLSIZE))
529 		entropy_bits = CRYPTO_BYTES2BITS(RNDPOOLSIZE);
530 
531 	swrand_stats.ss_entEst = entropy_bits;
532 	BUMP_SWRAND_STATS(ss_entIn, entropy_est);
533 }
534 
535 static void
swrand_add_entropy_later(uint8_t * ptr,size_t len)536 swrand_add_entropy_later(uint8_t *ptr, size_t len)
537 {
538 	mutex_enter(&buffer_lock);
539 	swrand_add_bytes_later(ptr, len);
540 	mutex_exit(&buffer_lock);
541 }
542 
543 static void
swrand_add_entropy(uint8_t * ptr,size_t len,uint16_t entropy_est)544 swrand_add_entropy(uint8_t *ptr, size_t len, uint16_t entropy_est)
545 {
546 	mutex_enter(&srndpool_lock);
547 	swrand_add_bytes(ptr, len);
548 	swrand_mix_pool(entropy_est);
549 	mutex_exit(&srndpool_lock);
550 }
551 
552 /*
553  * The physmem_* routines below generate entropy by reading blocks of
554  * physical memory.  Entropy is gathered in a couple of ways:
555  *
556  *  - By reading blocks of physical memory and detecting if changes
557  *    occurred in the blocks read.
558  *
559  *  - By measuring the time it takes to load and hash a block of memory
560  *    and computing the differences in the measured time.
561  *
562  * The first method was used in the CryptoRand implementation.  Physical
563  * memory is divided into blocks of fixed size.  A block of memory is
564  * chosen from the possible blocks and hashed to produce a digest.  This
565  * digest is then mixed into the pool.  A single bit from the digest is
566  * used as a parity bit or "checksum" and compared against the previous
567  * "checksum" computed for the block.  If the single-bit checksum has not
568  * changed, no entropy is credited to the pool.  If there is a change,
569  * then the assumption is that at least one bit in the block has changed.
570  * The possible locations within the memory block of where the bit change
571  * occurred is used as a measure of entropy.  For example, if a block
572  * size of 4096 bytes is used, about log_2(4096*8)=15 bits worth of
573  * entropy is available.  Because the single-bit checksum will miss half
574  * of the changes, the amount of entropy credited to the pool is doubled
575  * when a change is detected.  With a 4096 byte block size, a block
576  * change will add a total of 30 bits of entropy to the pool.
577  *
578  * The second method measures the amount of time it takes to read and
579  * hash a physical memory block (as described above).  The time measured
580  * can vary depending on system load, scheduling and other factors.
581  * Differences between consecutive measurements are computed to come up
582  * with an entropy estimate.  The first, second, and third order delta is
583  * calculated to determine the minimum delta value.  The number of bits
584  * present in this minimum delta value is the entropy estimate.  This
585  * entropy estimation technique using time deltas is similar to that used
586  * in /dev/random implementations from Linux/BSD.
587  */
588 
589 static int
physmem_ent_init(physmem_entsrc_t * entsrc)590 physmem_ent_init(physmem_entsrc_t *entsrc)
591 {
592 	uint8_t *ptr;
593 	int i;
594 
595 	bzero(entsrc, sizeof (*entsrc));
596 
597 	/*
598 	 * The maximum entropy amount in bits per block of memory read is
599 	 * log_2(MEMBLOCKSIZE * 8);
600 	 */
601 	i = CRYPTO_BYTES2BITS(MEMBLOCKSIZE);
602 	while (i >>= 1)
603 		entsrc->entperblock++;
604 
605 	/* Initialize entsrc->nblocks */
606 	physmem_count_blocks();
607 
608 	if (entsrc->nblocks == 0) {
609 		cmn_err(CE_WARN, "no memory blocks to scan!");
610 		return (-1);
611 	}
612 
613 	/* Allocate space for the parity vector and memory page */
614 	entsrc->parity = kmem_alloc(howmany(entsrc->nblocks, 8),
615 	    KM_SLEEP);
616 	entsrc->pmbuf = vmem_alloc(heap_arena, PAGESIZE, VM_SLEEP);
617 
618 
619 	/* Initialize parity vector with bits from the pool */
620 	i = howmany(entsrc->nblocks, 8);
621 	ptr = entsrc->parity;
622 	while (i > 0) {
623 		if (i > RNDPOOLSIZE) {
624 			bcopy(srndpool, ptr, RNDPOOLSIZE);
625 			mutex_enter(&srndpool_lock);
626 			swrand_mix_pool(0);
627 			mutex_exit(&srndpool_lock);
628 			ptr += RNDPOOLSIZE;
629 			i -= RNDPOOLSIZE;
630 		} else {
631 			bcopy(srndpool, ptr, i);
632 			break;
633 		}
634 	}
635 
636 	/* Generate some entropy to further initialize the pool */
637 	mutex_enter(&srndpool_lock);
638 	physmem_ent_gen(entsrc);
639 	entropy_bits = 0;
640 	mutex_exit(&srndpool_lock);
641 
642 	return (0);
643 }
644 
645 static void
physmem_ent_fini(physmem_entsrc_t * entsrc)646 physmem_ent_fini(physmem_entsrc_t *entsrc)
647 {
648 	if (entsrc->pmbuf != NULL)
649 		vmem_free(heap_arena, entsrc->pmbuf, PAGESIZE);
650 	if (entsrc->parity != NULL)
651 		kmem_free(entsrc->parity, howmany(entsrc->nblocks, 8));
652 	bzero(entsrc, sizeof (*entsrc));
653 }
654 
655 static void
physmem_ent_gen(physmem_entsrc_t * entsrc)656 physmem_ent_gen(physmem_entsrc_t *entsrc)
657 {
658 	struct memlist *pmem;
659 	offset_t offset, poffset;
660 	pfn_t pfn;
661 	int i, nbytes, len, ent = 0;
662 	uint32_t block, oblock;
663 	hrtime_t ts1, ts2, diff, delta, delta2, delta3;
664 	uint8_t digest[HASHSIZE];
665 	HASH_CTX ctx;
666 	page_t *pp;
667 
668 	/*
669 	 * Use each 32-bit quantity in the pool to pick a memory
670 	 * block to read.
671 	 */
672 	for (i = 0; i < RNDPOOLSIZE/4; i++) {
673 
674 		/* If the pool is "full", stop after one block */
675 		if (entropy_bits + ent >= CRYPTO_BYTES2BITS(RNDPOOLSIZE)) {
676 			if (i > 0)
677 				break;
678 		}
679 
680 		/*
681 		 * This lock protects reading of phys_install.
682 		 * Any changes to this list, by DR, are done while
683 		 * holding this lock. So, holding this lock is sufficient
684 		 * to handle DR also.
685 		 */
686 		memlist_read_lock();
687 
688 		/* We're left with less than 4K of memory after DR */
689 		ASSERT(entsrc->nblocks > 0);
690 
691 		/* Pick a memory block to read */
692 		block = oblock = srndpool[i] % entsrc->nblocks;
693 
694 		for (pmem = phys_install; pmem != NULL; pmem = pmem->ml_next) {
695 			if (block < pmem->ml_size / MEMBLOCKSIZE)
696 				break;
697 			block -= pmem->ml_size / MEMBLOCKSIZE;
698 		}
699 
700 		ASSERT(pmem != NULL);
701 
702 		offset = pmem->ml_address + block * MEMBLOCKSIZE;
703 
704 		if (!address_in_memlist(phys_install, offset, MEMBLOCKSIZE)) {
705 			memlist_read_unlock();
706 			continue;
707 		}
708 
709 		/*
710 		 * Do an initial check to see if the address is safe
711 		 */
712 		if (plat_hold_page(offset >> PAGESHIFT, PLAT_HOLD_NO_LOCK, NULL)
713 		    == PLAT_HOLD_FAIL) {
714 			memlist_read_unlock();
715 			continue;
716 		}
717 
718 		/*
719 		 * Figure out which page to load to read the
720 		 * memory block.  Load the page and compute the
721 		 * hash of the memory block.
722 		 */
723 		len = MEMBLOCKSIZE;
724 		ts1 = gethrtime();
725 		HashInit(&ctx);
726 		while (len) {
727 			pfn = offset >> PAGESHIFT;
728 			poffset = offset & PAGEOFFSET;
729 			nbytes = PAGESIZE - poffset < len ?
730 			    PAGESIZE - poffset : len;
731 
732 			/*
733 			 * Re-check the offset, and lock the frame.  If the
734 			 * page was given away after the above check, we'll
735 			 * just bail out.
736 			 */
737 			if (plat_hold_page(pfn, PLAT_HOLD_LOCK, &pp) ==
738 			    PLAT_HOLD_FAIL)
739 				break;
740 
741 			hat_devload(kas.a_hat, entsrc->pmbuf,
742 			    PAGESIZE, pfn, PROT_READ,
743 			    HAT_LOAD_NOCONSIST | HAT_LOAD_LOCK);
744 
745 			HashUpdate(&ctx, (uint8_t *)entsrc->pmbuf + poffset,
746 			    nbytes);
747 
748 			hat_unload(kas.a_hat, entsrc->pmbuf, PAGESIZE,
749 			    HAT_UNLOAD_UNLOCK);
750 
751 			plat_release_page(pp);
752 
753 			len -= nbytes;
754 			offset += nbytes;
755 		}
756 		/* We got our pages. Let the DR roll */
757 		memlist_read_unlock();
758 
759 		/* See if we had to bail out due to a page being given away */
760 		if (len)
761 			continue;
762 
763 		HashFinal(digest, &ctx);
764 		ts2 = gethrtime();
765 
766 		/*
767 		 * Compute the time it took to load and hash the
768 		 * block and compare it against the previous
769 		 * measurement. The delta of the time values
770 		 * provides a small amount of entropy.  The
771 		 * minimum of the first, second, and third order
772 		 * delta is used to estimate how much entropy
773 		 * is present.
774 		 */
775 		diff = ts2 - ts1;
776 		delta = diff - entsrc->last_diff;
777 		if (delta < 0)
778 			delta = -delta;
779 		delta2 = delta - entsrc->last_delta;
780 		if (delta2 < 0)
781 			delta2 = -delta2;
782 		delta3 = delta2 - entsrc->last_delta2;
783 		if (delta3 < 0)
784 			delta3 = -delta3;
785 		entsrc->last_diff = diff;
786 		entsrc->last_delta = delta;
787 		entsrc->last_delta2 = delta2;
788 
789 		if (delta > delta2)
790 			delta = delta2;
791 		if (delta > delta3)
792 			delta = delta3;
793 		delta2 = 0;
794 		while (delta >>= 1)
795 			delta2++;
796 		ent += delta2;
797 
798 		/*
799 		 * If the memory block has changed, credit the pool with
800 		 * the entropy estimate.  The entropy estimate is doubled
801 		 * because the single-bit checksum misses half the change
802 		 * on average.
803 		 */
804 		if (physmem_parity_update(entsrc->parity, oblock,
805 		    digest[0] & 1))
806 			ent += 2 * entsrc->entperblock;
807 
808 		/* Add the entropy bytes to the pool */
809 		swrand_add_bytes(digest, HASHSIZE);
810 		swrand_add_bytes((uint8_t *)&ts1, sizeof (ts1));
811 		swrand_add_bytes((uint8_t *)&ts2, sizeof (ts2));
812 	}
813 
814 	swrand_mix_pool(ent);
815 }
816 
817 static int
physmem_parity_update(uint8_t * parity_vec,uint32_t block,int parity)818 physmem_parity_update(uint8_t *parity_vec, uint32_t block, int parity)
819 {
820 	/* Test and set the parity bit, return 1 if changed */
821 	if (parity == ((parity_vec[block >> 3] >> (block & 7)) & 1))
822 		return (0);
823 	parity_vec[block >> 3] ^= 1 << (block & 7);
824 	return (1);
825 }
826 
827 /* Compute number of memory blocks available to scan */
828 static void
physmem_count_blocks()829 physmem_count_blocks()
830 {
831 	struct memlist *pmem;
832 
833 	memlist_read_lock();
834 	entsrc.nblocks = 0;
835 	for (pmem = phys_install; pmem != NULL; pmem = pmem->ml_next) {
836 		entsrc.nblocks += pmem->ml_size / MEMBLOCKSIZE;
837 		if (entsrc.nblocks > MAXMEMBLOCKS) {
838 			entsrc.nblocks = MAXMEMBLOCKS;
839 			break;
840 		}
841 	}
842 	memlist_read_unlock();
843 }
844 
845 /*
846  * Dynamic Reconfiguration call-back functions
847  */
848 
849 /* ARGSUSED */
850 static void
rnd_dr_callback_post_add(void * arg,pgcnt_t delta)851 rnd_dr_callback_post_add(void *arg, pgcnt_t delta)
852 {
853 	/* More memory is available now, so update entsrc->nblocks. */
854 	physmem_count_blocks();
855 }
856 
857 /* Call-back routine invoked before the DR starts a memory removal. */
858 /* ARGSUSED */
859 static int
rnd_dr_callback_pre_del(void * arg,pgcnt_t delta)860 rnd_dr_callback_pre_del(void *arg, pgcnt_t delta)
861 {
862 	return (0);
863 }
864 
865 /* Call-back routine invoked after the DR starts a memory removal. */
866 /* ARGSUSED */
867 static void
rnd_dr_callback_post_del(void * arg,pgcnt_t delta,int cancelled)868 rnd_dr_callback_post_del(void *arg, pgcnt_t delta, int cancelled)
869 {
870 	/* Memory has shrunk, so update entsrc->nblocks. */
871 	physmem_count_blocks();
872 }
873 
874 /* Timeout handling to gather entropy from physmem events */
875 static void
swrand_schedule_timeout(void)876 swrand_schedule_timeout(void)
877 {
878 	clock_t ut;	/* time in microseconds */
879 
880 	ASSERT(MUTEX_HELD(&srndpool_lock));
881 	/*
882 	 * The new timeout value is taken from the pool of random bits.
883 	 * We're merely reading the first 32 bits from the pool here, not
884 	 * consuming any entropy.
885 	 * This routine is usually called right after stirring the pool, so
886 	 * srndpool[0] will have a *fresh* random value each time.
887 	 * The timeout multiplier value is a random value between 0.7 sec and
888 	 * 1.748575 sec (0.7 sec + 0xFFFFF microseconds).
889 	 * The new timeout is TIMEOUT_INTERVAL times that multiplier.
890 	 */
891 	ut = 700000 + (clock_t)(srndpool[0] & 0xFFFFF);
892 	rnd_timeout_id = timeout(rnd_handler, NULL,
893 	    TIMEOUT_INTERVAL * drv_usectohz(ut));
894 }
895 
896 /*ARGSUSED*/
897 static void
rnd_handler(void * arg)898 rnd_handler(void *arg)
899 {
900 	mutex_enter(&srndpool_lock);
901 
902 	physmem_ent_gen(&entsrc);
903 	if (snum_waiters > 0)
904 		cv_broadcast(&srndpool_read_cv);
905 	swrand_schedule_timeout();
906 
907 	mutex_exit(&srndpool_lock);
908 }
909