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source: vbox/trunk/src/libs/openssl-1.1.1f/crypto/rand/rand_lib.c@ 83531

Last change on this file since 83531 was 83531, checked in by vboxsync, 5 years ago

setting svn:sync-process=export for openssl-1.1.1f, all files except tests

File size: 26.4 KB
Line 
1/*
2 * Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the OpenSSL license (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10#include <stdio.h>
11#include <time.h>
12#include "internal/cryptlib.h"
13#include <openssl/opensslconf.h>
14#include "crypto/rand.h"
15#include <openssl/engine.h>
16#include "internal/thread_once.h"
17#include "rand_local.h"
18#include "e_os.h"
19
20#ifndef OPENSSL_NO_ENGINE
21/* non-NULL if default_RAND_meth is ENGINE-provided */
22static ENGINE *funct_ref;
23static CRYPTO_RWLOCK *rand_engine_lock;
24#endif
25static CRYPTO_RWLOCK *rand_meth_lock;
26static const RAND_METHOD *default_RAND_meth;
27static CRYPTO_ONCE rand_init = CRYPTO_ONCE_STATIC_INIT;
28
29static CRYPTO_RWLOCK *rand_nonce_lock;
30static int rand_nonce_count;
31
32static int rand_inited = 0;
33
34#ifdef OPENSSL_RAND_SEED_RDTSC
35/*
36 * IMPORTANT NOTE: It is not currently possible to use this code
37 * because we are not sure about the amount of randomness it provides.
38 * Some SP900 tests have been run, but there is internal skepticism.
39 * So for now this code is not used.
40 */
41# error "RDTSC enabled? Should not be possible!"
42
43/*
44 * Acquire entropy from high-speed clock
45 *
46 * Since we get some randomness from the low-order bits of the
47 * high-speed clock, it can help.
48 *
49 * Returns the total entropy count, if it exceeds the requested
50 * entropy count. Otherwise, returns an entropy count of 0.
51 */
52size_t rand_acquire_entropy_from_tsc(RAND_POOL *pool)
53{
54 unsigned char c;
55 int i;
56
57 if ((OPENSSL_ia32cap_P[0] & (1 << 4)) != 0) {
58 for (i = 0; i < TSC_READ_COUNT; i++) {
59 c = (unsigned char)(OPENSSL_rdtsc() & 0xFF);
60 rand_pool_add(pool, &c, 1, 4);
61 }
62 }
63 return rand_pool_entropy_available(pool);
64}
65#endif
66
67#ifdef OPENSSL_RAND_SEED_RDCPU
68size_t OPENSSL_ia32_rdseed_bytes(unsigned char *buf, size_t len);
69size_t OPENSSL_ia32_rdrand_bytes(unsigned char *buf, size_t len);
70
71extern unsigned int OPENSSL_ia32cap_P[];
72
73/*
74 * Acquire entropy using Intel-specific cpu instructions
75 *
76 * Uses the RDSEED instruction if available, otherwise uses
77 * RDRAND if available.
78 *
79 * For the differences between RDSEED and RDRAND, and why RDSEED
80 * is the preferred choice, see https://goo.gl/oK3KcN
81 *
82 * Returns the total entropy count, if it exceeds the requested
83 * entropy count. Otherwise, returns an entropy count of 0.
84 */
85size_t rand_acquire_entropy_from_cpu(RAND_POOL *pool)
86{
87 size_t bytes_needed;
88 unsigned char *buffer;
89
90 bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
91 if (bytes_needed > 0) {
92 buffer = rand_pool_add_begin(pool, bytes_needed);
93
94 if (buffer != NULL) {
95 /* Whichever comes first, use RDSEED, RDRAND or nothing */
96 if ((OPENSSL_ia32cap_P[2] & (1 << 18)) != 0) {
97 if (OPENSSL_ia32_rdseed_bytes(buffer, bytes_needed)
98 == bytes_needed) {
99 rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed);
100 }
101 } else if ((OPENSSL_ia32cap_P[1] & (1 << (62 - 32))) != 0) {
102 if (OPENSSL_ia32_rdrand_bytes(buffer, bytes_needed)
103 == bytes_needed) {
104 rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed);
105 }
106 } else {
107 rand_pool_add_end(pool, 0, 0);
108 }
109 }
110 }
111
112 return rand_pool_entropy_available(pool);
113}
114#endif
115
116
117/*
118 * Implements the get_entropy() callback (see RAND_DRBG_set_callbacks())
119 *
120 * If the DRBG has a parent, then the required amount of entropy input
121 * is fetched using the parent's RAND_DRBG_generate().
122 *
123 * Otherwise, the entropy is polled from the system entropy sources
124 * using rand_pool_acquire_entropy().
125 *
126 * If a random pool has been added to the DRBG using RAND_add(), then
127 * its entropy will be used up first.
128 */
129size_t rand_drbg_get_entropy(RAND_DRBG *drbg,
130 unsigned char **pout,
131 int entropy, size_t min_len, size_t max_len,
132 int prediction_resistance)
133{
134 size_t ret = 0;
135 size_t entropy_available = 0;
136 RAND_POOL *pool;
137
138 if (drbg->parent != NULL && drbg->strength > drbg->parent->strength) {
139 /*
140 * We currently don't support the algorithm from NIST SP 800-90C
141 * 10.1.2 to use a weaker DRBG as source
142 */
143 RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY, RAND_R_PARENT_STRENGTH_TOO_WEAK);
144 return 0;
145 }
146
147 if (drbg->seed_pool != NULL) {
148 pool = drbg->seed_pool;
149 pool->entropy_requested = entropy;
150 } else {
151 pool = rand_pool_new(entropy, drbg->secure, min_len, max_len);
152 if (pool == NULL)
153 return 0;
154 }
155
156 if (drbg->parent != NULL) {
157 size_t bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
158 unsigned char *buffer = rand_pool_add_begin(pool, bytes_needed);
159
160 if (buffer != NULL) {
161 size_t bytes = 0;
162
163 /*
164 * Get random data from parent. Include our address as additional input,
165 * in order to provide some additional distinction between different
166 * DRBG child instances.
167 * Our lock is already held, but we need to lock our parent before
168 * generating bits from it. (Note: taking the lock will be a no-op
169 * if locking if drbg->parent->lock == NULL.)
170 */
171 rand_drbg_lock(drbg->parent);
172 if (RAND_DRBG_generate(drbg->parent,
173 buffer, bytes_needed,
174 prediction_resistance,
175 (unsigned char *)&drbg, sizeof(drbg)) != 0)
176 bytes = bytes_needed;
177 drbg->reseed_next_counter
178 = tsan_load(&drbg->parent->reseed_prop_counter);
179 rand_drbg_unlock(drbg->parent);
180
181 rand_pool_add_end(pool, bytes, 8 * bytes);
182 entropy_available = rand_pool_entropy_available(pool);
183 }
184
185 } else {
186 if (prediction_resistance) {
187 /*
188 * We don't have any entropy sources that comply with the NIST
189 * standard to provide prediction resistance (see NIST SP 800-90C,
190 * Section 5.4).
191 */
192 RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY,
193 RAND_R_PREDICTION_RESISTANCE_NOT_SUPPORTED);
194 goto err;
195 }
196
197 /* Get entropy by polling system entropy sources. */
198 entropy_available = rand_pool_acquire_entropy(pool);
199 }
200
201 if (entropy_available > 0) {
202 ret = rand_pool_length(pool);
203 *pout = rand_pool_detach(pool);
204 }
205
206 err:
207 if (drbg->seed_pool == NULL)
208 rand_pool_free(pool);
209 return ret;
210}
211
212/*
213 * Implements the cleanup_entropy() callback (see RAND_DRBG_set_callbacks())
214 *
215 */
216void rand_drbg_cleanup_entropy(RAND_DRBG *drbg,
217 unsigned char *out, size_t outlen)
218{
219 if (drbg->seed_pool == NULL) {
220 if (drbg->secure)
221 OPENSSL_secure_clear_free(out, outlen);
222 else
223 OPENSSL_clear_free(out, outlen);
224 }
225}
226
227
228/*
229 * Implements the get_nonce() callback (see RAND_DRBG_set_callbacks())
230 *
231 */
232size_t rand_drbg_get_nonce(RAND_DRBG *drbg,
233 unsigned char **pout,
234 int entropy, size_t min_len, size_t max_len)
235{
236 size_t ret = 0;
237 RAND_POOL *pool;
238
239 struct {
240 void * instance;
241 int count;
242 } data;
243
244 memset(&data, 0, sizeof(data));
245 pool = rand_pool_new(0, 0, min_len, max_len);
246 if (pool == NULL)
247 return 0;
248
249 if (rand_pool_add_nonce_data(pool) == 0)
250 goto err;
251
252 data.instance = drbg;
253 CRYPTO_atomic_add(&rand_nonce_count, 1, &data.count, rand_nonce_lock);
254
255 if (rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0) == 0)
256 goto err;
257
258 ret = rand_pool_length(pool);
259 *pout = rand_pool_detach(pool);
260
261 err:
262 rand_pool_free(pool);
263
264 return ret;
265}
266
267/*
268 * Implements the cleanup_nonce() callback (see RAND_DRBG_set_callbacks())
269 *
270 */
271void rand_drbg_cleanup_nonce(RAND_DRBG *drbg,
272 unsigned char *out, size_t outlen)
273{
274 OPENSSL_clear_free(out, outlen);
275}
276
277/*
278 * Generate additional data that can be used for the drbg. The data does
279 * not need to contain entropy, but it's useful if it contains at least
280 * some bits that are unpredictable.
281 *
282 * Returns 0 on failure.
283 *
284 * On success it allocates a buffer at |*pout| and returns the length of
285 * the data. The buffer should get freed using OPENSSL_secure_clear_free().
286 */
287size_t rand_drbg_get_additional_data(RAND_POOL *pool, unsigned char **pout)
288{
289 size_t ret = 0;
290
291 if (rand_pool_add_additional_data(pool) == 0)
292 goto err;
293
294 ret = rand_pool_length(pool);
295 *pout = rand_pool_detach(pool);
296
297 err:
298 return ret;
299}
300
301void rand_drbg_cleanup_additional_data(RAND_POOL *pool, unsigned char *out)
302{
303 rand_pool_reattach(pool, out);
304}
305
306DEFINE_RUN_ONCE_STATIC(do_rand_init)
307{
308#ifndef OPENSSL_NO_ENGINE
309 rand_engine_lock = CRYPTO_THREAD_lock_new();
310 if (rand_engine_lock == NULL)
311 return 0;
312#endif
313
314 rand_meth_lock = CRYPTO_THREAD_lock_new();
315 if (rand_meth_lock == NULL)
316 goto err1;
317
318 rand_nonce_lock = CRYPTO_THREAD_lock_new();
319 if (rand_nonce_lock == NULL)
320 goto err2;
321
322 if (!rand_pool_init())
323 goto err3;
324
325 rand_inited = 1;
326 return 1;
327
328err3:
329 CRYPTO_THREAD_lock_free(rand_nonce_lock);
330 rand_nonce_lock = NULL;
331err2:
332 CRYPTO_THREAD_lock_free(rand_meth_lock);
333 rand_meth_lock = NULL;
334err1:
335#ifndef OPENSSL_NO_ENGINE
336 CRYPTO_THREAD_lock_free(rand_engine_lock);
337 rand_engine_lock = NULL;
338#endif
339 return 0;
340}
341
342void rand_cleanup_int(void)
343{
344 const RAND_METHOD *meth = default_RAND_meth;
345
346 if (!rand_inited)
347 return;
348
349 if (meth != NULL && meth->cleanup != NULL)
350 meth->cleanup();
351 RAND_set_rand_method(NULL);
352 rand_pool_cleanup();
353#ifndef OPENSSL_NO_ENGINE
354 CRYPTO_THREAD_lock_free(rand_engine_lock);
355 rand_engine_lock = NULL;
356#endif
357 CRYPTO_THREAD_lock_free(rand_meth_lock);
358 rand_meth_lock = NULL;
359 CRYPTO_THREAD_lock_free(rand_nonce_lock);
360 rand_nonce_lock = NULL;
361 rand_inited = 0;
362}
363
364/*
365 * RAND_close_seed_files() ensures that any seed file descriptors are
366 * closed after use.
367 */
368void RAND_keep_random_devices_open(int keep)
369{
370 if (RUN_ONCE(&rand_init, do_rand_init))
371 rand_pool_keep_random_devices_open(keep);
372}
373
374/*
375 * RAND_poll() reseeds the default RNG using random input
376 *
377 * The random input is obtained from polling various entropy
378 * sources which depend on the operating system and are
379 * configurable via the --with-rand-seed configure option.
380 */
381int RAND_poll(void)
382{
383 int ret = 0;
384
385 RAND_POOL *pool = NULL;
386
387 const RAND_METHOD *meth = RAND_get_rand_method();
388
389 if (meth == NULL)
390 return 0;
391
392 if (meth == RAND_OpenSSL()) {
393 /* fill random pool and seed the master DRBG */
394 RAND_DRBG *drbg = RAND_DRBG_get0_master();
395
396 if (drbg == NULL)
397 return 0;
398
399 rand_drbg_lock(drbg);
400 ret = rand_drbg_restart(drbg, NULL, 0, 0);
401 rand_drbg_unlock(drbg);
402
403 return ret;
404
405 } else {
406 /* fill random pool and seed the current legacy RNG */
407 pool = rand_pool_new(RAND_DRBG_STRENGTH, 1,
408 (RAND_DRBG_STRENGTH + 7) / 8,
409 RAND_POOL_MAX_LENGTH);
410 if (pool == NULL)
411 return 0;
412
413 if (rand_pool_acquire_entropy(pool) == 0)
414 goto err;
415
416 if (meth->add == NULL
417 || meth->add(rand_pool_buffer(pool),
418 rand_pool_length(pool),
419 (rand_pool_entropy(pool) / 8.0)) == 0)
420 goto err;
421
422 ret = 1;
423 }
424
425err:
426 rand_pool_free(pool);
427 return ret;
428}
429
430/*
431 * Allocate memory and initialize a new random pool
432 */
433
434RAND_POOL *rand_pool_new(int entropy_requested, int secure,
435 size_t min_len, size_t max_len)
436{
437 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
438 size_t min_alloc_size = RAND_POOL_MIN_ALLOCATION(secure);
439
440 if (pool == NULL) {
441 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
442 return NULL;
443 }
444
445 pool->min_len = min_len;
446 pool->max_len = (max_len > RAND_POOL_MAX_LENGTH) ?
447 RAND_POOL_MAX_LENGTH : max_len;
448 pool->alloc_len = min_len < min_alloc_size ? min_alloc_size : min_len;
449 if (pool->alloc_len > pool->max_len)
450 pool->alloc_len = pool->max_len;
451
452 if (secure)
453 pool->buffer = OPENSSL_secure_zalloc(pool->alloc_len);
454 else
455 pool->buffer = OPENSSL_zalloc(pool->alloc_len);
456
457 if (pool->buffer == NULL) {
458 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
459 goto err;
460 }
461
462 pool->entropy_requested = entropy_requested;
463 pool->secure = secure;
464
465 return pool;
466
467err:
468 OPENSSL_free(pool);
469 return NULL;
470}
471
472/*
473 * Attach new random pool to the given buffer
474 *
475 * This function is intended to be used only for feeding random data
476 * provided by RAND_add() and RAND_seed() into the <master> DRBG.
477 */
478RAND_POOL *rand_pool_attach(const unsigned char *buffer, size_t len,
479 size_t entropy)
480{
481 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
482
483 if (pool == NULL) {
484 RANDerr(RAND_F_RAND_POOL_ATTACH, ERR_R_MALLOC_FAILURE);
485 return NULL;
486 }
487
488 /*
489 * The const needs to be cast away, but attached buffers will not be
490 * modified (in contrary to allocated buffers which are zeroed and
491 * freed in the end).
492 */
493 pool->buffer = (unsigned char *) buffer;
494 pool->len = len;
495
496 pool->attached = 1;
497
498 pool->min_len = pool->max_len = pool->alloc_len = pool->len;
499 pool->entropy = entropy;
500
501 return pool;
502}
503
504/*
505 * Free |pool|, securely erasing its buffer.
506 */
507void rand_pool_free(RAND_POOL *pool)
508{
509 if (pool == NULL)
510 return;
511
512 /*
513 * Although it would be advisable from a cryptographical viewpoint,
514 * we are not allowed to clear attached buffers, since they are passed
515 * to rand_pool_attach() as `const unsigned char*`.
516 * (see corresponding comment in rand_pool_attach()).
517 */
518 if (!pool->attached) {
519 if (pool->secure)
520 OPENSSL_secure_clear_free(pool->buffer, pool->alloc_len);
521 else
522 OPENSSL_clear_free(pool->buffer, pool->alloc_len);
523 }
524
525 OPENSSL_free(pool);
526}
527
528/*
529 * Return the |pool|'s buffer to the caller (readonly).
530 */
531const unsigned char *rand_pool_buffer(RAND_POOL *pool)
532{
533 return pool->buffer;
534}
535
536/*
537 * Return the |pool|'s entropy to the caller.
538 */
539size_t rand_pool_entropy(RAND_POOL *pool)
540{
541 return pool->entropy;
542}
543
544/*
545 * Return the |pool|'s buffer length to the caller.
546 */
547size_t rand_pool_length(RAND_POOL *pool)
548{
549 return pool->len;
550}
551
552/*
553 * Detach the |pool| buffer and return it to the caller.
554 * It's the responsibility of the caller to free the buffer
555 * using OPENSSL_secure_clear_free() or to re-attach it
556 * again to the pool using rand_pool_reattach().
557 */
558unsigned char *rand_pool_detach(RAND_POOL *pool)
559{
560 unsigned char *ret = pool->buffer;
561 pool->buffer = NULL;
562 pool->entropy = 0;
563 return ret;
564}
565
566/*
567 * Re-attach the |pool| buffer. It is only allowed to pass
568 * the |buffer| which was previously detached from the same pool.
569 */
570void rand_pool_reattach(RAND_POOL *pool, unsigned char *buffer)
571{
572 pool->buffer = buffer;
573 OPENSSL_cleanse(pool->buffer, pool->len);
574 pool->len = 0;
575}
576
577/*
578 * If |entropy_factor| bits contain 1 bit of entropy, how many bytes does one
579 * need to obtain at least |bits| bits of entropy?
580 */
581#define ENTROPY_TO_BYTES(bits, entropy_factor) \
582 (((bits) * (entropy_factor) + 7) / 8)
583
584
585/*
586 * Checks whether the |pool|'s entropy is available to the caller.
587 * This is the case when entropy count and buffer length are high enough.
588 * Returns
589 *
590 * |entropy| if the entropy count and buffer size is large enough
591 * 0 otherwise
592 */
593size_t rand_pool_entropy_available(RAND_POOL *pool)
594{
595 if (pool->entropy < pool->entropy_requested)
596 return 0;
597
598 if (pool->len < pool->min_len)
599 return 0;
600
601 return pool->entropy;
602}
603
604/*
605 * Returns the (remaining) amount of entropy needed to fill
606 * the random pool.
607 */
608
609size_t rand_pool_entropy_needed(RAND_POOL *pool)
610{
611 if (pool->entropy < pool->entropy_requested)
612 return pool->entropy_requested - pool->entropy;
613
614 return 0;
615}
616
617/* Increase the allocation size -- not usable for an attached pool */
618static int rand_pool_grow(RAND_POOL *pool, size_t len)
619{
620 if (len > pool->alloc_len - pool->len) {
621 unsigned char *p;
622 const size_t limit = pool->max_len / 2;
623 size_t newlen = pool->alloc_len;
624
625 if (pool->attached || len > pool->max_len - pool->len) {
626 RANDerr(RAND_F_RAND_POOL_GROW, ERR_R_INTERNAL_ERROR);
627 return 0;
628 }
629
630 do
631 newlen = newlen < limit ? newlen * 2 : pool->max_len;
632 while (len > newlen - pool->len);
633
634 if (pool->secure)
635 p = OPENSSL_secure_zalloc(newlen);
636 else
637 p = OPENSSL_zalloc(newlen);
638 if (p == NULL) {
639 RANDerr(RAND_F_RAND_POOL_GROW, ERR_R_MALLOC_FAILURE);
640 return 0;
641 }
642 memcpy(p, pool->buffer, pool->len);
643 if (pool->secure)
644 OPENSSL_secure_clear_free(pool->buffer, pool->alloc_len);
645 else
646 OPENSSL_clear_free(pool->buffer, pool->alloc_len);
647 pool->buffer = p;
648 pool->alloc_len = newlen;
649 }
650 return 1;
651}
652
653/*
654 * Returns the number of bytes needed to fill the pool, assuming
655 * the input has 1 / |entropy_factor| entropy bits per data bit.
656 * In case of an error, 0 is returned.
657 */
658
659size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_factor)
660{
661 size_t bytes_needed;
662 size_t entropy_needed = rand_pool_entropy_needed(pool);
663
664 if (entropy_factor < 1) {
665 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_ARGUMENT_OUT_OF_RANGE);
666 return 0;
667 }
668
669 bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_factor);
670
671 if (bytes_needed > pool->max_len - pool->len) {
672 /* not enough space left */
673 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_RANDOM_POOL_OVERFLOW);
674 return 0;
675 }
676
677 if (pool->len < pool->min_len &&
678 bytes_needed < pool->min_len - pool->len)
679 /* to meet the min_len requirement */
680 bytes_needed = pool->min_len - pool->len;
681
682 /*
683 * Make sure the buffer is large enough for the requested amount
684 * of data. This guarantees that existing code patterns where
685 * rand_pool_add_begin, rand_pool_add_end or rand_pool_add
686 * are used to collect entropy data without any error handling
687 * whatsoever, continue to be valid.
688 * Furthermore if the allocation here fails once, make sure that
689 * we don't fall back to a less secure or even blocking random source,
690 * as that could happen by the existing code patterns.
691 * This is not a concern for additional data, therefore that
692 * is not needed if rand_pool_grow fails in other places.
693 */
694 if (!rand_pool_grow(pool, bytes_needed)) {
695 /* persistent error for this pool */
696 pool->max_len = pool->len = 0;
697 return 0;
698 }
699
700 return bytes_needed;
701}
702
703/* Returns the remaining number of bytes available */
704size_t rand_pool_bytes_remaining(RAND_POOL *pool)
705{
706 return pool->max_len - pool->len;
707}
708
709/*
710 * Add random bytes to the random pool.
711 *
712 * It is expected that the |buffer| contains |len| bytes of
713 * random input which contains at least |entropy| bits of
714 * randomness.
715 *
716 * Returns 1 if the added amount is adequate, otherwise 0
717 */
718int rand_pool_add(RAND_POOL *pool,
719 const unsigned char *buffer, size_t len, size_t entropy)
720{
721 if (len > pool->max_len - pool->len) {
722 RANDerr(RAND_F_RAND_POOL_ADD, RAND_R_ENTROPY_INPUT_TOO_LONG);
723 return 0;
724 }
725
726 if (pool->buffer == NULL) {
727 RANDerr(RAND_F_RAND_POOL_ADD, ERR_R_INTERNAL_ERROR);
728 return 0;
729 }
730
731 if (len > 0) {
732 /*
733 * This is to protect us from accidentally passing the buffer
734 * returned from rand_pool_add_begin.
735 * The check for alloc_len makes sure we do not compare the
736 * address of the end of the allocated memory to something
737 * different, since that comparison would have an
738 * indeterminate result.
739 */
740 if (pool->alloc_len > pool->len && pool->buffer + pool->len == buffer) {
741 RANDerr(RAND_F_RAND_POOL_ADD, ERR_R_INTERNAL_ERROR);
742 return 0;
743 }
744 /*
745 * We have that only for cases when a pool is used to collect
746 * additional data.
747 * For entropy data, as long as the allocation request stays within
748 * the limits given by rand_pool_bytes_needed this rand_pool_grow
749 * below is guaranteed to succeed, thus no allocation happens.
750 */
751 if (!rand_pool_grow(pool, len))
752 return 0;
753 memcpy(pool->buffer + pool->len, buffer, len);
754 pool->len += len;
755 pool->entropy += entropy;
756 }
757
758 return 1;
759}
760
761/*
762 * Start to add random bytes to the random pool in-place.
763 *
764 * Reserves the next |len| bytes for adding random bytes in-place
765 * and returns a pointer to the buffer.
766 * The caller is allowed to copy up to |len| bytes into the buffer.
767 * If |len| == 0 this is considered a no-op and a NULL pointer
768 * is returned without producing an error message.
769 *
770 * After updating the buffer, rand_pool_add_end() needs to be called
771 * to finish the update operation (see next comment).
772 */
773unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len)
774{
775 if (len == 0)
776 return NULL;
777
778 if (len > pool->max_len - pool->len) {
779 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, RAND_R_RANDOM_POOL_OVERFLOW);
780 return NULL;
781 }
782
783 if (pool->buffer == NULL) {
784 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, ERR_R_INTERNAL_ERROR);
785 return NULL;
786 }
787
788 /*
789 * As long as the allocation request stays within the limits given
790 * by rand_pool_bytes_needed this rand_pool_grow below is guaranteed
791 * to succeed, thus no allocation happens.
792 * We have that only for cases when a pool is used to collect
793 * additional data. Then the buffer might need to grow here,
794 * and of course the caller is responsible to check the return
795 * value of this function.
796 */
797 if (!rand_pool_grow(pool, len))
798 return NULL;
799
800 return pool->buffer + pool->len;
801}
802
803/*
804 * Finish to add random bytes to the random pool in-place.
805 *
806 * Finishes an in-place update of the random pool started by
807 * rand_pool_add_begin() (see previous comment).
808 * It is expected that |len| bytes of random input have been added
809 * to the buffer which contain at least |entropy| bits of randomness.
810 * It is allowed to add less bytes than originally reserved.
811 */
812int rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy)
813{
814 if (len > pool->alloc_len - pool->len) {
815 RANDerr(RAND_F_RAND_POOL_ADD_END, RAND_R_RANDOM_POOL_OVERFLOW);
816 return 0;
817 }
818
819 if (len > 0) {
820 pool->len += len;
821 pool->entropy += entropy;
822 }
823
824 return 1;
825}
826
827int RAND_set_rand_method(const RAND_METHOD *meth)
828{
829 if (!RUN_ONCE(&rand_init, do_rand_init))
830 return 0;
831
832 CRYPTO_THREAD_write_lock(rand_meth_lock);
833#ifndef OPENSSL_NO_ENGINE
834 ENGINE_finish(funct_ref);
835 funct_ref = NULL;
836#endif
837 default_RAND_meth = meth;
838 CRYPTO_THREAD_unlock(rand_meth_lock);
839 return 1;
840}
841
842const RAND_METHOD *RAND_get_rand_method(void)
843{
844 const RAND_METHOD *tmp_meth = NULL;
845
846 if (!RUN_ONCE(&rand_init, do_rand_init))
847 return NULL;
848
849 CRYPTO_THREAD_write_lock(rand_meth_lock);
850 if (default_RAND_meth == NULL) {
851#ifndef OPENSSL_NO_ENGINE
852 ENGINE *e;
853
854 /* If we have an engine that can do RAND, use it. */
855 if ((e = ENGINE_get_default_RAND()) != NULL
856 && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
857 funct_ref = e;
858 default_RAND_meth = tmp_meth;
859 } else {
860 ENGINE_finish(e);
861 default_RAND_meth = &rand_meth;
862 }
863#else
864 default_RAND_meth = &rand_meth;
865#endif
866 }
867 tmp_meth = default_RAND_meth;
868 CRYPTO_THREAD_unlock(rand_meth_lock);
869 return tmp_meth;
870}
871
872#ifndef OPENSSL_NO_ENGINE
873int RAND_set_rand_engine(ENGINE *engine)
874{
875 const RAND_METHOD *tmp_meth = NULL;
876
877 if (!RUN_ONCE(&rand_init, do_rand_init))
878 return 0;
879
880 if (engine != NULL) {
881 if (!ENGINE_init(engine))
882 return 0;
883 tmp_meth = ENGINE_get_RAND(engine);
884 if (tmp_meth == NULL) {
885 ENGINE_finish(engine);
886 return 0;
887 }
888 }
889 CRYPTO_THREAD_write_lock(rand_engine_lock);
890 /* This function releases any prior ENGINE so call it first */
891 RAND_set_rand_method(tmp_meth);
892 funct_ref = engine;
893 CRYPTO_THREAD_unlock(rand_engine_lock);
894 return 1;
895}
896#endif
897
898void RAND_seed(const void *buf, int num)
899{
900 const RAND_METHOD *meth = RAND_get_rand_method();
901
902 if (meth != NULL && meth->seed != NULL)
903 meth->seed(buf, num);
904}
905
906void RAND_add(const void *buf, int num, double randomness)
907{
908 const RAND_METHOD *meth = RAND_get_rand_method();
909
910 if (meth != NULL && meth->add != NULL)
911 meth->add(buf, num, randomness);
912}
913
914/*
915 * This function is not part of RAND_METHOD, so if we're not using
916 * the default method, then just call RAND_bytes(). Otherwise make
917 * sure we're instantiated and use the private DRBG.
918 */
919int RAND_priv_bytes(unsigned char *buf, int num)
920{
921 const RAND_METHOD *meth = RAND_get_rand_method();
922 RAND_DRBG *drbg;
923
924 if (meth != NULL && meth != RAND_OpenSSL())
925 return RAND_bytes(buf, num);
926
927 drbg = RAND_DRBG_get0_private();
928 if (drbg != NULL)
929 return RAND_DRBG_bytes(drbg, buf, num);
930
931 return 0;
932}
933
934int RAND_bytes(unsigned char *buf, int num)
935{
936 const RAND_METHOD *meth = RAND_get_rand_method();
937
938 if (meth != NULL && meth->bytes != NULL)
939 return meth->bytes(buf, num);
940 RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
941 return -1;
942}
943
944#if OPENSSL_API_COMPAT < 0x10100000L
945int RAND_pseudo_bytes(unsigned char *buf, int num)
946{
947 const RAND_METHOD *meth = RAND_get_rand_method();
948
949 if (meth != NULL && meth->pseudorand != NULL)
950 return meth->pseudorand(buf, num);
951 RANDerr(RAND_F_RAND_PSEUDO_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
952 return -1;
953}
954#endif
955
956int RAND_status(void)
957{
958 const RAND_METHOD *meth = RAND_get_rand_method();
959
960 if (meth != NULL && meth->status != NULL)
961 return meth->status();
962 return 0;
963}
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