2 * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the Apache License 2.0 (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
12 #include "internal/cryptlib.h"
13 #include <openssl/opensslconf.h>
14 #include "internal/rand_int.h"
15 #include <openssl/engine.h>
16 #include "internal/thread_once.h"
21 # ifndef OPENSSL_NO_ENGINE
22 /* non-NULL if default_RAND_meth is ENGINE-provided */
23 static ENGINE *funct_ref;
24 static CRYPTO_RWLOCK *rand_engine_lock;
26 static CRYPTO_RWLOCK *rand_meth_lock;
27 static const RAND_METHOD *default_RAND_meth;
28 static CRYPTO_ONCE rand_init = CRYPTO_ONCE_STATIC_INIT;
30 static int rand_inited = 0;
31 #endif /* FIPS_MODE */
35 #ifdef OPENSSL_RAND_SEED_RDTSC
37 * IMPORTANT NOTE: It is not currently possible to use this code
38 * because we are not sure about the amount of randomness it provides.
39 * Some SP900 tests have been run, but there is internal skepticism.
40 * So for now this code is not used.
42 # error "RDTSC enabled? Should not be possible!"
45 * Acquire entropy from high-speed clock
47 * Since we get some randomness from the low-order bits of the
48 * high-speed clock, it can help.
50 * Returns the total entropy count, if it exceeds the requested
51 * entropy count. Otherwise, returns an entropy count of 0.
53 size_t rand_acquire_entropy_from_tsc(RAND_POOL *pool)
58 if ((OPENSSL_ia32cap_P[0] & (1 << 4)) != 0) {
59 for (i = 0; i < TSC_READ_COUNT; i++) {
60 c = (unsigned char)(OPENSSL_rdtsc() & 0xFF);
61 rand_pool_add(pool, &c, 1, 4);
64 return rand_pool_entropy_available(pool);
68 #ifdef OPENSSL_RAND_SEED_RDCPU
69 size_t OPENSSL_ia32_rdseed_bytes(unsigned char *buf, size_t len);
70 size_t OPENSSL_ia32_rdrand_bytes(unsigned char *buf, size_t len);
72 extern unsigned int OPENSSL_ia32cap_P[];
75 * Acquire entropy using Intel-specific cpu instructions
77 * Uses the RDSEED instruction if available, otherwise uses
78 * RDRAND if available.
80 * For the differences between RDSEED and RDRAND, and why RDSEED
81 * is the preferred choice, see https://goo.gl/oK3KcN
83 * Returns the total entropy count, if it exceeds the requested
84 * entropy count. Otherwise, returns an entropy count of 0.
86 size_t rand_acquire_entropy_from_cpu(RAND_POOL *pool)
89 unsigned char *buffer;
91 bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
92 if (bytes_needed > 0) {
93 buffer = rand_pool_add_begin(pool, bytes_needed);
96 /* Whichever comes first, use RDSEED, RDRAND or nothing */
97 if ((OPENSSL_ia32cap_P[2] & (1 << 18)) != 0) {
98 if (OPENSSL_ia32_rdseed_bytes(buffer, bytes_needed)
100 rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed);
102 } else if ((OPENSSL_ia32cap_P[1] & (1 << (62 - 32))) != 0) {
103 if (OPENSSL_ia32_rdrand_bytes(buffer, bytes_needed)
105 rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed);
108 rand_pool_add_end(pool, 0, 0);
113 return rand_pool_entropy_available(pool);
119 * Implements the get_entropy() callback (see RAND_DRBG_set_callbacks())
121 * If the DRBG has a parent, then the required amount of entropy input
122 * is fetched using the parent's RAND_DRBG_generate().
124 * Otherwise, the entropy is polled from the system entropy sources
125 * using rand_pool_acquire_entropy().
127 * If a random pool has been added to the DRBG using RAND_add(), then
128 * its entropy will be used up first.
130 size_t rand_drbg_get_entropy(RAND_DRBG *drbg,
131 unsigned char **pout,
132 int entropy, size_t min_len, size_t max_len,
133 int prediction_resistance)
136 size_t entropy_available = 0;
139 if (drbg->parent != NULL && drbg->strength > drbg->parent->strength) {
141 * We currently don't support the algorithm from NIST SP 800-90C
142 * 10.1.2 to use a weaker DRBG as source
144 RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY, RAND_R_PARENT_STRENGTH_TOO_WEAK);
148 if (drbg->seed_pool != NULL) {
149 pool = drbg->seed_pool;
150 pool->entropy_requested = entropy;
152 pool = rand_pool_new(entropy, drbg->secure, min_len, max_len);
157 if (drbg->parent != NULL) {
158 size_t bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
159 unsigned char *buffer = rand_pool_add_begin(pool, bytes_needed);
161 if (buffer != NULL) {
165 * Get random from parent, include our state as additional input.
166 * Our lock is already held, but we need to lock our parent before
167 * generating bits from it. (Note: taking the lock will be a no-op
168 * if locking if drbg->parent->lock == NULL.)
170 rand_drbg_lock(drbg->parent);
171 if (RAND_DRBG_generate(drbg->parent,
172 buffer, bytes_needed,
173 prediction_resistance,
175 bytes = bytes_needed;
176 drbg->reseed_next_counter
177 = tsan_load(&drbg->parent->reseed_prop_counter);
178 rand_drbg_unlock(drbg->parent);
180 rand_pool_add_end(pool, bytes, 8 * bytes);
181 entropy_available = rand_pool_entropy_available(pool);
185 /* Get entropy by polling system entropy sources. */
186 entropy_available = rand_pool_acquire_entropy(pool);
189 if (entropy_available > 0) {
190 ret = rand_pool_length(pool);
191 *pout = rand_pool_detach(pool);
194 if (drbg->seed_pool == NULL)
195 rand_pool_free(pool);
200 * Implements the cleanup_entropy() callback (see RAND_DRBG_set_callbacks())
203 void rand_drbg_cleanup_entropy(RAND_DRBG *drbg,
204 unsigned char *out, size_t outlen)
206 if (drbg->seed_pool == NULL) {
208 OPENSSL_secure_clear_free(out, outlen);
210 OPENSSL_clear_free(out, outlen);
215 * Generate additional data that can be used for the drbg. The data does
216 * not need to contain entropy, but it's useful if it contains at least
217 * some bits that are unpredictable.
219 * Returns 0 on failure.
221 * On success it allocates a buffer at |*pout| and returns the length of
222 * the data. The buffer should get freed using OPENSSL_secure_clear_free().
224 size_t rand_drbg_get_additional_data(RAND_POOL *pool, unsigned char **pout)
228 if (rand_pool_add_additional_data(pool) == 0)
231 ret = rand_pool_length(pool);
232 *pout = rand_pool_detach(pool);
238 void rand_drbg_cleanup_additional_data(RAND_POOL *pool, unsigned char *out)
240 rand_pool_reattach(pool, out);
249 DEFINE_RUN_ONCE_STATIC(do_rand_init)
251 # ifndef OPENSSL_NO_ENGINE
252 rand_engine_lock = CRYPTO_THREAD_lock_new();
253 if (rand_engine_lock == NULL)
257 rand_meth_lock = CRYPTO_THREAD_lock_new();
258 if (rand_meth_lock == NULL)
261 if (!rand_pool_init())
268 CRYPTO_THREAD_lock_free(rand_meth_lock);
269 rand_meth_lock = NULL;
270 # ifndef OPENSSL_NO_ENGINE
271 CRYPTO_THREAD_lock_free(rand_engine_lock);
272 rand_engine_lock = NULL;
277 void rand_cleanup_int(void)
279 const RAND_METHOD *meth = default_RAND_meth;
284 if (meth != NULL && meth->cleanup != NULL)
286 RAND_set_rand_method(NULL);
288 # ifndef OPENSSL_NO_ENGINE
289 CRYPTO_THREAD_lock_free(rand_engine_lock);
290 rand_engine_lock = NULL;
292 CRYPTO_THREAD_lock_free(rand_meth_lock);
293 rand_meth_lock = NULL;
297 /* TODO(3.0): Do we need to handle this somehow in the FIPS module? */
299 * RAND_close_seed_files() ensures that any seed file descriptors are
302 void RAND_keep_random_devices_open(int keep)
304 if (RUN_ONCE(&rand_init, do_rand_init))
305 rand_pool_keep_random_devices_open(keep);
309 * RAND_poll() reseeds the default RNG using random input
311 * The random input is obtained from polling various entropy
312 * sources which depend on the operating system and are
313 * configurable via the --with-rand-seed configure option.
319 const RAND_METHOD *meth = RAND_get_rand_method();
321 if (meth == RAND_OpenSSL()) {
322 /* fill random pool and seed the master DRBG */
323 RAND_DRBG *drbg = RAND_DRBG_get0_master();
328 rand_drbg_lock(drbg);
329 ret = rand_drbg_restart(drbg, NULL, 0, 0);
330 rand_drbg_unlock(drbg);
335 RAND_POOL *pool = NULL;
337 /* fill random pool and seed the current legacy RNG */
338 pool = rand_pool_new(RAND_DRBG_STRENGTH, 1,
339 (RAND_DRBG_STRENGTH + 7) / 8,
340 RAND_POOL_MAX_LENGTH);
344 if (rand_pool_acquire_entropy(pool) == 0)
347 if (meth->add == NULL
348 || meth->add(rand_pool_buffer(pool),
349 rand_pool_length(pool),
350 (rand_pool_entropy(pool) / 8.0)) == 0)
356 rand_pool_free(pool);
361 #endif /* FIPS_MODE */
364 * Allocate memory and initialize a new random pool
367 RAND_POOL *rand_pool_new(int entropy_requested, int secure,
368 size_t min_len, size_t max_len)
370 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
371 size_t min_alloc_size = RAND_POOL_MIN_ALLOCATION(secure);
374 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
378 pool->min_len = min_len;
379 pool->max_len = (max_len > RAND_POOL_MAX_LENGTH) ?
380 RAND_POOL_MAX_LENGTH : max_len;
381 pool->alloc_len = min_len < min_alloc_size ? min_alloc_size : min_len;
382 if (pool->alloc_len > pool->max_len)
383 pool->alloc_len = pool->max_len;
386 pool->buffer = OPENSSL_secure_zalloc(pool->alloc_len);
388 pool->buffer = OPENSSL_zalloc(pool->alloc_len);
390 if (pool->buffer == NULL) {
391 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
395 pool->entropy_requested = entropy_requested;
396 pool->secure = secure;
406 * Attach new random pool to the given buffer
408 * This function is intended to be used only for feeding random data
409 * provided by RAND_add() and RAND_seed() into the <master> DRBG.
411 RAND_POOL *rand_pool_attach(const unsigned char *buffer, size_t len,
414 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
417 RANDerr(RAND_F_RAND_POOL_ATTACH, ERR_R_MALLOC_FAILURE);
422 * The const needs to be cast away, but attached buffers will not be
423 * modified (in contrary to allocated buffers which are zeroed and
426 pool->buffer = (unsigned char *) buffer;
431 pool->min_len = pool->max_len = pool->alloc_len = pool->len;
432 pool->entropy = entropy;
438 * Free |pool|, securely erasing its buffer.
440 void rand_pool_free(RAND_POOL *pool)
446 * Although it would be advisable from a cryptographical viewpoint,
447 * we are not allowed to clear attached buffers, since they are passed
448 * to rand_pool_attach() as `const unsigned char*`.
449 * (see corresponding comment in rand_pool_attach()).
451 if (!pool->attached) {
453 OPENSSL_secure_clear_free(pool->buffer, pool->alloc_len);
455 OPENSSL_clear_free(pool->buffer, pool->alloc_len);
462 * Return the |pool|'s buffer to the caller (readonly).
464 const unsigned char *rand_pool_buffer(RAND_POOL *pool)
470 * Return the |pool|'s entropy to the caller.
472 size_t rand_pool_entropy(RAND_POOL *pool)
474 return pool->entropy;
478 * Return the |pool|'s buffer length to the caller.
480 size_t rand_pool_length(RAND_POOL *pool)
486 * Detach the |pool| buffer and return it to the caller.
487 * It's the responsibility of the caller to free the buffer
488 * using OPENSSL_secure_clear_free() or to re-attach it
489 * again to the pool using rand_pool_reattach().
491 unsigned char *rand_pool_detach(RAND_POOL *pool)
493 unsigned char *ret = pool->buffer;
500 * Re-attach the |pool| buffer. It is only allowed to pass
501 * the |buffer| which was previously detached from the same pool.
503 void rand_pool_reattach(RAND_POOL *pool, unsigned char *buffer)
505 pool->buffer = buffer;
506 OPENSSL_cleanse(pool->buffer, pool->len);
511 * If |entropy_factor| bits contain 1 bit of entropy, how many bytes does one
512 * need to obtain at least |bits| bits of entropy?
514 #define ENTROPY_TO_BYTES(bits, entropy_factor) \
515 (((bits) * (entropy_factor) + 7) / 8)
519 * Checks whether the |pool|'s entropy is available to the caller.
520 * This is the case when entropy count and buffer length are high enough.
523 * |entropy| if the entropy count and buffer size is large enough
526 size_t rand_pool_entropy_available(RAND_POOL *pool)
528 if (pool->entropy < pool->entropy_requested)
531 if (pool->len < pool->min_len)
534 return pool->entropy;
538 * Returns the (remaining) amount of entropy needed to fill
542 size_t rand_pool_entropy_needed(RAND_POOL *pool)
544 if (pool->entropy < pool->entropy_requested)
545 return pool->entropy_requested - pool->entropy;
551 * Returns the number of bytes needed to fill the pool, assuming
552 * the input has 1 / |entropy_factor| entropy bits per data bit.
553 * In case of an error, 0 is returned.
556 size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_factor)
559 size_t entropy_needed = rand_pool_entropy_needed(pool);
561 if (entropy_factor < 1) {
562 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_ARGUMENT_OUT_OF_RANGE);
566 bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_factor);
568 if (bytes_needed > pool->max_len - pool->len) {
569 /* not enough space left */
570 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_RANDOM_POOL_OVERFLOW);
574 if (pool->len < pool->min_len &&
575 bytes_needed < pool->min_len - pool->len)
576 /* to meet the min_len requirement */
577 bytes_needed = pool->min_len - pool->len;
582 /* Returns the remaining number of bytes available */
583 size_t rand_pool_bytes_remaining(RAND_POOL *pool)
585 return pool->max_len - pool->len;
588 static int rand_pool_grow(RAND_POOL *pool, size_t len)
590 if (len > pool->alloc_len - pool->len) {
592 const size_t limit = pool->max_len / 2;
593 size_t newlen = pool->alloc_len;
596 newlen = newlen < limit ? newlen * 2 : pool->max_len;
597 while (len > newlen - pool->len);
600 p = OPENSSL_secure_zalloc(newlen);
602 p = OPENSSL_zalloc(newlen);
604 RANDerr(RAND_F_RAND_POOL_GROW, ERR_R_MALLOC_FAILURE);
607 memcpy(p, pool->buffer, pool->len);
609 OPENSSL_secure_clear_free(pool->buffer, pool->alloc_len);
611 OPENSSL_clear_free(pool->buffer, pool->alloc_len);
613 pool->alloc_len = newlen;
619 * Add random bytes to the random pool.
621 * It is expected that the |buffer| contains |len| bytes of
622 * random input which contains at least |entropy| bits of
625 * Returns 1 if the added amount is adequate, otherwise 0
627 int rand_pool_add(RAND_POOL *pool,
628 const unsigned char *buffer, size_t len, size_t entropy)
630 if (len > pool->max_len - pool->len) {
631 RANDerr(RAND_F_RAND_POOL_ADD, RAND_R_ENTROPY_INPUT_TOO_LONG);
635 if (pool->buffer == NULL) {
636 RANDerr(RAND_F_RAND_POOL_ADD, ERR_R_INTERNAL_ERROR);
641 if (!rand_pool_grow(pool, len))
643 memcpy(pool->buffer + pool->len, buffer, len);
645 pool->entropy += entropy;
652 * Start to add random bytes to the random pool in-place.
654 * Reserves the next |len| bytes for adding random bytes in-place
655 * and returns a pointer to the buffer.
656 * The caller is allowed to copy up to |len| bytes into the buffer.
657 * If |len| == 0 this is considered a no-op and a NULL pointer
658 * is returned without producing an error message.
660 * After updating the buffer, rand_pool_add_end() needs to be called
661 * to finish the udpate operation (see next comment).
663 unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len)
668 if (len > pool->max_len - pool->len) {
669 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, RAND_R_RANDOM_POOL_OVERFLOW);
673 if (pool->buffer == NULL) {
674 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, ERR_R_INTERNAL_ERROR);
678 if (!rand_pool_grow(pool, len))
680 return pool->buffer + pool->len;
684 * Finish to add random bytes to the random pool in-place.
686 * Finishes an in-place update of the random pool started by
687 * rand_pool_add_begin() (see previous comment).
688 * It is expected that |len| bytes of random input have been added
689 * to the buffer which contain at least |entropy| bits of randomness.
690 * It is allowed to add less bytes than originally reserved.
692 int rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy)
694 if (len > pool->max_len - pool->len) {
695 RANDerr(RAND_F_RAND_POOL_ADD_END, RAND_R_RANDOM_POOL_OVERFLOW);
701 pool->entropy += entropy;
708 int RAND_set_rand_method(const RAND_METHOD *meth)
710 if (!RUN_ONCE(&rand_init, do_rand_init))
713 CRYPTO_THREAD_write_lock(rand_meth_lock);
714 # ifndef OPENSSL_NO_ENGINE
715 ENGINE_finish(funct_ref);
718 default_RAND_meth = meth;
719 CRYPTO_THREAD_unlock(rand_meth_lock);
724 const RAND_METHOD *RAND_get_rand_method(void)
729 const RAND_METHOD *tmp_meth = NULL;
731 if (!RUN_ONCE(&rand_init, do_rand_init))
734 CRYPTO_THREAD_write_lock(rand_meth_lock);
735 if (default_RAND_meth == NULL) {
736 # ifndef OPENSSL_NO_ENGINE
739 /* If we have an engine that can do RAND, use it. */
740 if ((e = ENGINE_get_default_RAND()) != NULL
741 && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
743 default_RAND_meth = tmp_meth;
746 default_RAND_meth = &rand_meth;
749 default_RAND_meth = &rand_meth;
752 tmp_meth = default_RAND_meth;
753 CRYPTO_THREAD_unlock(rand_meth_lock);
758 #if !defined(OPENSSL_NO_ENGINE) && !defined(FIPS_MODE)
759 int RAND_set_rand_engine(ENGINE *engine)
761 const RAND_METHOD *tmp_meth = NULL;
763 if (!RUN_ONCE(&rand_init, do_rand_init))
766 if (engine != NULL) {
767 if (!ENGINE_init(engine))
769 tmp_meth = ENGINE_get_RAND(engine);
770 if (tmp_meth == NULL) {
771 ENGINE_finish(engine);
775 CRYPTO_THREAD_write_lock(rand_engine_lock);
776 /* This function releases any prior ENGINE so call it first */
777 RAND_set_rand_method(tmp_meth);
779 CRYPTO_THREAD_unlock(rand_engine_lock);
784 void RAND_seed(const void *buf, int num)
786 const RAND_METHOD *meth = RAND_get_rand_method();
788 if (meth->seed != NULL)
789 meth->seed(buf, num);
792 void RAND_add(const void *buf, int num, double randomness)
794 const RAND_METHOD *meth = RAND_get_rand_method();
796 if (meth->add != NULL)
797 meth->add(buf, num, randomness);
801 * This function is not part of RAND_METHOD, so if we're not using
802 * the default method, then just call RAND_bytes(). Otherwise make
803 * sure we're instantiated and use the private DRBG.
805 int rand_priv_bytes_ex(OPENSSL_CTX *ctx, unsigned char *buf, int num)
809 const RAND_METHOD *meth = RAND_get_rand_method();
811 if (meth != RAND_OpenSSL())
812 return meth->bytes(buf, num);
814 drbg = OPENSSL_CTX_get0_private_drbg(ctx);
818 ret = RAND_DRBG_bytes(drbg, buf, num);
822 int RAND_priv_bytes(unsigned char *buf, int num)
824 return rand_priv_bytes_ex(NULL, buf, num);
827 int rand_bytes_ex(OPENSSL_CTX *ctx, unsigned char *buf, int num)
831 const RAND_METHOD *meth = RAND_get_rand_method();
833 if (meth != RAND_OpenSSL()) {
834 if (meth->bytes != NULL)
835 return meth->bytes(buf, num);
836 RANDerr(RAND_F_RAND_BYTES_EX, RAND_R_FUNC_NOT_IMPLEMENTED);
840 drbg = OPENSSL_CTX_get0_public_drbg(ctx);
844 ret = RAND_DRBG_bytes(drbg, buf, num);
848 int RAND_bytes(unsigned char *buf, int num)
850 return rand_bytes_ex(NULL, buf, num);
853 #if !OPENSSL_API_1_1_0 && !defined(FIPS_MODE)
854 int RAND_pseudo_bytes(unsigned char *buf, int num)
856 const RAND_METHOD *meth = RAND_get_rand_method();
858 if (meth->pseudorand != NULL)
859 return meth->pseudorand(buf, num);
864 int RAND_status(void)
866 const RAND_METHOD *meth = RAND_get_rand_method();
868 if (meth->status != NULL)
869 return meth->status();