2 * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
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
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"
18 #ifdef OPENSSL_SYS_UNIX
19 # include <sys/types.h>
21 # include <sys/time.h>
25 /* Macro to convert two thirty two bit values into a sixty four bit one */
26 #define TWO32TO64(a, b) ((((uint64_t)(a)) << 32) + (b))
29 * Check for the existence and support of POSIX timers. The standard
30 * says that the _POSIX_TIMERS macro will have a positive value if they
33 * However, we want an additional constraint: that the timer support does
34 * not require an extra library dependency. Early versions of glibc
35 * require -lrt to be specified on the link line to access the timers,
36 * so this needs to be checked for.
38 * It is worse because some libraries define __GLIBC__ but don't
39 * support the version testing macro (e.g. uClibc). This means
40 * an extra check is needed.
42 * The final condition is:
43 * "have posix timers and either not glibc or glibc without -lrt"
45 * The nested #if sequences are required to avoid using a parameterised
46 * macro that might be undefined.
48 #undef OSSL_POSIX_TIMER_OKAY
49 #if defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0
50 # if defined(__GLIBC__)
51 # if defined(__GLIBC_PREREQ)
52 # if __GLIBC_PREREQ(2, 17)
53 # define OSSL_POSIX_TIMER_OKAY
57 # define OSSL_POSIX_TIMER_OKAY
61 #ifndef OPENSSL_NO_ENGINE
62 /* non-NULL if default_RAND_meth is ENGINE-provided */
63 static ENGINE *funct_ref;
64 static CRYPTO_RWLOCK *rand_engine_lock;
66 static CRYPTO_RWLOCK *rand_meth_lock;
67 static const RAND_METHOD *default_RAND_meth;
68 static CRYPTO_ONCE rand_init = CRYPTO_ONCE_STATIC_INIT;
72 #ifdef OPENSSL_RAND_SEED_RDTSC
74 * IMPORTANT NOTE: It is not currently possible to use this code
75 * because we are not sure about the amount of randomness it provides.
76 * Some SP900 tests have been run, but there is internal skepticism.
77 * So for now this code is not used.
79 # error "RDTSC enabled? Should not be possible!"
82 * Acquire entropy from high-speed clock
84 * Since we get some randomness from the low-order bits of the
85 * high-speed clock, it can help.
87 * Returns the total entropy count, if it exceeds the requested
88 * entropy count. Otherwise, returns an entropy count of 0.
90 size_t rand_acquire_entropy_from_tsc(RAND_POOL *pool)
95 if ((OPENSSL_ia32cap_P[0] & (1 << 4)) != 0) {
96 for (i = 0; i < TSC_READ_COUNT; i++) {
97 c = (unsigned char)(OPENSSL_rdtsc() & 0xFF);
98 rand_pool_add(pool, &c, 1, 4);
101 return rand_pool_entropy_available(pool);
105 #ifdef OPENSSL_RAND_SEED_RDCPU
106 size_t OPENSSL_ia32_rdseed_bytes(unsigned char *buf, size_t len);
107 size_t OPENSSL_ia32_rdrand_bytes(unsigned char *buf, size_t len);
109 extern unsigned int OPENSSL_ia32cap_P[];
112 * Acquire entropy using Intel-specific cpu instructions
114 * Uses the RDSEED instruction if available, otherwise uses
115 * RDRAND if available.
117 * For the differences between RDSEED and RDRAND, and why RDSEED
118 * is the preferred choice, see https://goo.gl/oK3KcN
120 * Returns the total entropy count, if it exceeds the requested
121 * entropy count. Otherwise, returns an entropy count of 0.
123 size_t rand_acquire_entropy_from_cpu(RAND_POOL *pool)
126 unsigned char *buffer;
128 bytes_needed = rand_pool_bytes_needed(pool, 8 /*entropy_per_byte*/);
129 if (bytes_needed > 0) {
130 buffer = rand_pool_add_begin(pool, bytes_needed);
132 if (buffer != NULL) {
133 /* Whichever comes first, use RDSEED, RDRAND or nothing */
134 if ((OPENSSL_ia32cap_P[2] & (1 << 18)) != 0) {
135 if (OPENSSL_ia32_rdseed_bytes(buffer, bytes_needed)
137 rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed);
139 } else if ((OPENSSL_ia32cap_P[1] & (1 << (62 - 32))) != 0) {
140 if (OPENSSL_ia32_rdrand_bytes(buffer, bytes_needed)
142 rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed);
145 rand_pool_add_end(pool, 0, 0);
150 return rand_pool_entropy_available(pool);
156 * Implements the get_entropy() callback (see RAND_DRBG_set_callbacks())
158 * If the DRBG has a parent, then the required amount of entropy input
159 * is fetched using the parent's RAND_DRBG_generate().
161 * Otherwise, the entropy is polled from the system entropy sources
162 * using rand_pool_acquire_entropy().
164 * If a random pool has been added to the DRBG using RAND_add(), then
165 * its entropy will be used up first.
167 size_t rand_drbg_get_entropy(RAND_DRBG *drbg,
168 unsigned char **pout,
169 int entropy, size_t min_len, size_t max_len,
170 int prediction_resistance)
173 size_t entropy_available = 0;
176 if (drbg->parent && drbg->strength > drbg->parent->strength) {
178 * We currently don't support the algorithm from NIST SP 800-90C
179 * 10.1.2 to use a weaker DRBG as source
181 RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY, RAND_R_PARENT_STRENGTH_TOO_WEAK);
185 pool = rand_pool_new(entropy, min_len, max_len);
191 rand_pool_buffer(drbg->pool),
192 rand_pool_length(drbg->pool),
193 rand_pool_entropy(drbg->pool));
194 rand_pool_free(drbg->pool);
199 size_t bytes_needed = rand_pool_bytes_needed(pool, 8);
200 unsigned char *buffer = rand_pool_add_begin(pool, bytes_needed);
202 if (buffer != NULL) {
206 * Get random from parent, include our state as additional input.
207 * Our lock is already held, but we need to lock our parent before
208 * generating bits from it. (Note: taking the lock will be a no-op
209 * if locking if drbg->parent->lock == NULL.)
211 rand_drbg_lock(drbg->parent);
212 if (RAND_DRBG_generate(drbg->parent,
213 buffer, bytes_needed,
214 prediction_resistance,
215 (unsigned char *)drbg, sizeof(*drbg)) != 0)
216 bytes = bytes_needed;
217 rand_drbg_unlock(drbg->parent);
219 rand_pool_add_end(pool, bytes, 8 * bytes);
220 entropy_available = rand_pool_entropy_available(pool);
224 if (prediction_resistance) {
226 * We don't have any entropy sources that comply with the NIST
227 * standard to provide prediction resistance (see NIST SP 800-90C,
230 RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY,
231 RAND_R_PREDICTION_RESISTANCE_NOT_SUPPORTED);
235 /* Get entropy by polling system entropy sources. */
236 entropy_available = rand_pool_acquire_entropy(pool);
239 if (entropy_available > 0) {
240 ret = rand_pool_length(pool);
241 *pout = rand_pool_detach(pool);
245 rand_pool_free(pool);
250 * Find a suitable source of time. Start with the highest resolution source
251 * and work down to the slower ones. This is added as additional data and
252 * isn't counted as randomness, so any result is acceptable.
254 * Returns 0 when we weren't able to find any time source
256 static uint64_t get_timer_bits(void)
258 uint64_t res = OPENSSL_rdtsc();
267 if (QueryPerformanceCounter(&t) != 0)
269 GetSystemTimeAsFileTime(&ft);
270 return TWO32TO64(ft.dwHighDateTime, ft.dwLowDateTime);
272 #elif defined(__sun) || defined(__hpux)
278 read_wall_time(&t, TIMEBASE_SZ);
279 return TWO32TO64(t.tb_high, t.tb_low);
283 # if defined(OSSL_POSIX_TIMER_OKAY)
288 # ifdef CLOCK_BOOTTIME
289 cid = CLOCK_BOOTTIME;
290 # elif defined(_POSIX_MONOTONIC_CLOCK)
291 cid = CLOCK_MONOTONIC;
293 cid = CLOCK_REALTIME;
296 if (clock_gettime(cid, &ts) == 0)
297 return TWO32TO64(ts.tv_sec, ts.tv_nsec);
300 # if defined(__unix__) \
301 || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
305 if (gettimeofday(&tv, NULL) == 0)
306 return TWO32TO64(tv.tv_sec, tv.tv_usec);
310 time_t t = time(NULL);
319 * Generate additional data that can be used for the drbg. The data does
320 * not need to contain entropy, but it's useful if it contains at least
321 * some bits that are unpredictable.
323 * Returns 0 on failure.
325 * On success it allocates a buffer at |*pout| and returns the length of
326 * the data. The buffer should get freed using OPENSSL_secure_clear_free().
328 size_t rand_drbg_get_additional_data(unsigned char **pout, size_t max_len)
331 CRYPTO_THREAD_ID thread_id;
333 #ifdef OPENSSL_SYS_UNIX
335 #elif defined(OPENSSL_SYS_WIN32)
340 pool = rand_pool_new(0, 0, max_len);
344 #ifdef OPENSSL_SYS_UNIX
346 rand_pool_add(pool, (unsigned char *)&pid, sizeof(pid), 0);
347 #elif defined(OPENSSL_SYS_WIN32)
348 pid = GetCurrentProcessId();
349 rand_pool_add(pool, (unsigned char *)&pid, sizeof(pid), 0);
352 thread_id = CRYPTO_THREAD_get_current_id();
354 rand_pool_add(pool, (unsigned char *)&thread_id, sizeof(thread_id), 0);
356 tbits = get_timer_bits();
358 rand_pool_add(pool, (unsigned char *)&tbits, sizeof(tbits), 0);
360 /* TODO: Use RDSEED? */
362 len = rand_pool_length(pool);
364 *pout = rand_pool_detach(pool);
365 rand_pool_free(pool);
371 * Implements the cleanup_entropy() callback (see RAND_DRBG_set_callbacks())
374 void rand_drbg_cleanup_entropy(RAND_DRBG *drbg,
375 unsigned char *out, size_t outlen)
377 OPENSSL_secure_clear_free(out, outlen);
385 DEFINE_RUN_ONCE_STATIC(do_rand_init)
389 #ifndef OPENSSL_NO_ENGINE
390 rand_engine_lock = CRYPTO_THREAD_lock_new();
391 ret &= rand_engine_lock != NULL;
393 rand_meth_lock = CRYPTO_THREAD_lock_new();
394 ret &= rand_meth_lock != NULL;
399 void rand_cleanup_int(void)
401 const RAND_METHOD *meth = default_RAND_meth;
403 if (meth != NULL && meth->cleanup != NULL)
405 RAND_set_rand_method(NULL);
406 #ifndef OPENSSL_NO_ENGINE
407 CRYPTO_THREAD_lock_free(rand_engine_lock);
409 CRYPTO_THREAD_lock_free(rand_meth_lock);
413 * RAND_poll() reseeds the default RNG using random input
415 * The random input is obtained from polling various entropy
416 * sources which depend on the operating system and are
417 * configurable via the --with-rand-seed configure option.
423 RAND_POOL *pool = NULL;
425 const RAND_METHOD *meth = RAND_get_rand_method();
427 if (meth == RAND_OpenSSL()) {
428 /* fill random pool and seed the master DRBG */
429 RAND_DRBG *drbg = RAND_DRBG_get0_master();
434 rand_drbg_lock(drbg);
435 ret = rand_drbg_restart(drbg, NULL, 0, 0);
436 rand_drbg_unlock(drbg);
441 /* fill random pool and seed the current legacy RNG */
442 pool = rand_pool_new(RAND_DRBG_STRENGTH,
443 RAND_DRBG_STRENGTH / 8,
444 DRBG_MINMAX_FACTOR * (RAND_DRBG_STRENGTH / 8));
448 if (rand_pool_acquire_entropy(pool) == 0)
451 if (meth->add == NULL
452 || meth->add(rand_pool_buffer(pool),
453 rand_pool_length(pool),
454 (rand_pool_entropy(pool) / 8.0)) == 0)
461 rand_pool_free(pool);
466 * Allocate memory and initialize a new random pool
469 RAND_POOL *rand_pool_new(int entropy, size_t min_len, size_t max_len)
471 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
474 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
478 pool->min_len = min_len;
479 pool->max_len = max_len;
481 pool->buffer = OPENSSL_secure_zalloc(pool->max_len);
482 if (pool->buffer == NULL) {
483 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
487 pool->requested_entropy = entropy;
497 * Free |pool|, securely erasing its buffer.
499 void rand_pool_free(RAND_POOL *pool)
504 OPENSSL_secure_clear_free(pool->buffer, pool->max_len);
509 * Return the |pool|'s buffer to the caller (readonly).
511 const unsigned char *rand_pool_buffer(RAND_POOL *pool)
517 * Return the |pool|'s entropy to the caller.
519 size_t rand_pool_entropy(RAND_POOL *pool)
521 return pool->entropy;
525 * Return the |pool|'s buffer length to the caller.
527 size_t rand_pool_length(RAND_POOL *pool)
533 * Detach the |pool| buffer and return it to the caller.
534 * It's the responsibility of the caller to free the buffer
535 * using OPENSSL_secure_clear_free().
537 unsigned char *rand_pool_detach(RAND_POOL *pool)
539 unsigned char *ret = pool->buffer;
546 * If every byte of the input contains |entropy_per_bytes| bits of entropy,
547 * how many bytes does one need to obtain at least |bits| bits of entropy?
549 #define ENTROPY_TO_BYTES(bits, entropy_per_bytes) \
550 (((bits) + ((entropy_per_bytes) - 1))/(entropy_per_bytes))
554 * Checks whether the |pool|'s entropy is available to the caller.
555 * This is the case when entropy count and buffer length are high enough.
558 * |entropy| if the entropy count and buffer size is large enough
561 size_t rand_pool_entropy_available(RAND_POOL *pool)
563 if (pool->entropy < pool->requested_entropy)
566 if (pool->len < pool->min_len)
569 return pool->entropy;
573 * Returns the (remaining) amount of entropy needed to fill
577 size_t rand_pool_entropy_needed(RAND_POOL *pool)
579 if (pool->entropy < pool->requested_entropy)
580 return pool->requested_entropy - pool->entropy;
586 * Returns the number of bytes needed to fill the pool, assuming
587 * the input has 'entropy_per_byte' entropy bits per byte.
588 * In case of an error, 0 is returned.
591 size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_per_byte)
594 size_t entropy_needed = rand_pool_entropy_needed(pool);
596 if (entropy_per_byte < 1 || entropy_per_byte > 8) {
597 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_ARGUMENT_OUT_OF_RANGE);
601 bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_per_byte);
603 if (bytes_needed > pool->max_len - pool->len) {
604 /* not enough space left */
605 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_RANDOM_POOL_OVERFLOW);
609 if (pool->len < pool->min_len &&
610 bytes_needed < pool->min_len - pool->len)
611 /* to meet the min_len requirement */
612 bytes_needed = pool->min_len - pool->len;
617 /* Returns the remaining number of bytes available */
618 size_t rand_pool_bytes_remaining(RAND_POOL *pool)
620 return pool->max_len - pool->len;
624 * Add random bytes to the random pool.
626 * It is expected that the |buffer| contains |len| bytes of
627 * random input which contains at least |entropy| bits of
630 * Returns 1 if the added amount is adequate, otherwise 0
632 int rand_pool_add(RAND_POOL *pool,
633 const unsigned char *buffer, size_t len, size_t entropy)
635 if (len > pool->max_len - pool->len) {
636 RANDerr(RAND_F_RAND_POOL_ADD, RAND_R_ENTROPY_INPUT_TOO_LONG);
641 memcpy(pool->buffer + pool->len, buffer, len);
643 pool->entropy += entropy;
650 * Start to add random bytes to the random pool in-place.
652 * Reserves the next |len| bytes for adding random bytes in-place
653 * and returns a pointer to the buffer.
654 * The caller is allowed to copy up to |len| bytes into the buffer.
655 * If |len| == 0 this is considered a no-op and a NULL pointer
656 * is returned without producing an error message.
658 * After updating the buffer, rand_pool_add_end() needs to be called
659 * to finish the udpate operation (see next comment).
661 unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len)
666 if (len > pool->max_len - pool->len) {
667 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, RAND_R_RANDOM_POOL_OVERFLOW);
671 return pool->buffer + pool->len;
675 * Finish to add random bytes to the random pool in-place.
677 * Finishes an in-place update of the random pool started by
678 * rand_pool_add_begin() (see previous comment).
679 * It is expected that |len| bytes of random input have been added
680 * to the buffer which contain at least |entropy| bits of randomness.
681 * It is allowed to add less bytes than originally reserved.
683 int rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy)
685 if (len > pool->max_len - pool->len) {
686 RANDerr(RAND_F_RAND_POOL_ADD_END, RAND_R_RANDOM_POOL_OVERFLOW);
692 pool->entropy += entropy;
698 int RAND_set_rand_method(const RAND_METHOD *meth)
700 if (!RUN_ONCE(&rand_init, do_rand_init))
703 CRYPTO_THREAD_write_lock(rand_meth_lock);
704 #ifndef OPENSSL_NO_ENGINE
705 ENGINE_finish(funct_ref);
708 default_RAND_meth = meth;
709 CRYPTO_THREAD_unlock(rand_meth_lock);
713 const RAND_METHOD *RAND_get_rand_method(void)
715 const RAND_METHOD *tmp_meth = NULL;
717 if (!RUN_ONCE(&rand_init, do_rand_init))
720 CRYPTO_THREAD_write_lock(rand_meth_lock);
721 if (default_RAND_meth == NULL) {
722 #ifndef OPENSSL_NO_ENGINE
725 /* If we have an engine that can do RAND, use it. */
726 if ((e = ENGINE_get_default_RAND()) != NULL
727 && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
729 default_RAND_meth = tmp_meth;
732 default_RAND_meth = &rand_meth;
735 default_RAND_meth = &rand_meth;
738 tmp_meth = default_RAND_meth;
739 CRYPTO_THREAD_unlock(rand_meth_lock);
743 #ifndef OPENSSL_NO_ENGINE
744 int RAND_set_rand_engine(ENGINE *engine)
746 const RAND_METHOD *tmp_meth = NULL;
748 if (!RUN_ONCE(&rand_init, do_rand_init))
751 if (engine != NULL) {
752 if (!ENGINE_init(engine))
754 tmp_meth = ENGINE_get_RAND(engine);
755 if (tmp_meth == NULL) {
756 ENGINE_finish(engine);
760 CRYPTO_THREAD_write_lock(rand_engine_lock);
761 /* This function releases any prior ENGINE so call it first */
762 RAND_set_rand_method(tmp_meth);
764 CRYPTO_THREAD_unlock(rand_engine_lock);
769 void RAND_seed(const void *buf, int num)
771 const RAND_METHOD *meth = RAND_get_rand_method();
773 if (meth->seed != NULL)
774 meth->seed(buf, num);
777 void RAND_add(const void *buf, int num, double randomness)
779 const RAND_METHOD *meth = RAND_get_rand_method();
781 if (meth->add != NULL)
782 meth->add(buf, num, randomness);
786 * This function is not part of RAND_METHOD, so if we're not using
787 * the default method, then just call RAND_bytes(). Otherwise make
788 * sure we're instantiated and use the private DRBG.
790 int RAND_priv_bytes(unsigned char *buf, int num)
792 const RAND_METHOD *meth = RAND_get_rand_method();
796 if (meth != RAND_OpenSSL())
797 return RAND_bytes(buf, num);
799 drbg = RAND_DRBG_get0_private();
803 ret = RAND_DRBG_bytes(drbg, buf, num);
807 int RAND_bytes(unsigned char *buf, int num)
809 const RAND_METHOD *meth = RAND_get_rand_method();
811 if (meth->bytes != NULL)
812 return meth->bytes(buf, num);
813 RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
817 #if OPENSSL_API_COMPAT < 0x10100000L
818 int RAND_pseudo_bytes(unsigned char *buf, int num)
820 const RAND_METHOD *meth = RAND_get_rand_method();
822 if (meth->pseudorand != NULL)
823 return meth->pseudorand(buf, num);
828 int RAND_status(void)
830 const RAND_METHOD *meth = RAND_get_rand_method();
832 if (meth->status != NULL)
833 return meth->status();