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) {
134 /* If RDSEED is available, use that. */
135 if ((OPENSSL_ia32cap_P[2] & (1 << 18)) != 0) {
136 if (OPENSSL_ia32_rdseed_bytes(buffer, bytes_needed)
138 return rand_pool_add_end(pool,
143 /* Second choice is RDRAND. */
144 if ((OPENSSL_ia32cap_P[1] & (1 << (62 - 32))) != 0) {
145 if (OPENSSL_ia32_rdrand_bytes(buffer, bytes_needed)
147 return rand_pool_add_end(pool,
152 return rand_pool_add_end(pool, 0, 0);
156 return rand_pool_entropy_available(pool);
162 * Implements the get_entropy() callback (see RAND_DRBG_set_callbacks())
164 * If the DRBG has a parent, then the required amount of entropy input
165 * is fetched using the parent's RAND_DRBG_generate().
167 * Otherwise, the entropy is polled from the system entropy sources
168 * using rand_pool_acquire_entropy().
170 * If a random pool has been added to the DRBG using RAND_add(), then
171 * its entropy will be used up first.
173 size_t rand_drbg_get_entropy(RAND_DRBG *drbg,
174 unsigned char **pout,
175 int entropy, size_t min_len, size_t max_len,
176 int prediction_resistance)
179 size_t entropy_available = 0;
182 if (drbg->parent && drbg->strength > drbg->parent->strength) {
184 * We currently don't support the algorithm from NIST SP 800-90C
185 * 10.1.2 to use a weaker DRBG as source
187 RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY, RAND_R_PARENT_STRENGTH_TOO_WEAK);
191 pool = rand_pool_new(entropy, min_len, max_len);
197 rand_pool_buffer(drbg->pool),
198 rand_pool_length(drbg->pool),
199 rand_pool_entropy(drbg->pool));
200 rand_pool_free(drbg->pool);
205 size_t bytes_needed = rand_pool_bytes_needed(pool, 8);
206 unsigned char *buffer = rand_pool_add_begin(pool, bytes_needed);
208 if (buffer != NULL) {
212 * Get random from parent, include our state as additional input.
213 * Our lock is already held, but we need to lock our parent before
214 * generating bits from it. (Note: taking the lock will be a no-op
215 * if locking if drbg->parent->lock == NULL.)
217 rand_drbg_lock(drbg->parent);
218 if (RAND_DRBG_generate(drbg->parent,
219 buffer, bytes_needed,
221 (unsigned char *)drbg, sizeof(*drbg)) != 0)
222 bytes = bytes_needed;
223 rand_drbg_unlock(drbg->parent);
225 entropy_available = rand_pool_add_end(pool, bytes, 8 * bytes);
229 /* Get entropy by polling system entropy sources. */
230 entropy_available = rand_pool_acquire_entropy(pool);
233 if (entropy_available > 0) {
234 ret = rand_pool_length(pool);
235 *pout = rand_pool_detach(pool);
238 rand_pool_free(pool);
243 * Find a suitable source of time. Start with the highest resolution source
244 * and work down to the slower ones. This is added as additional data and
245 * isn't counted as randomness, so any result is acceptable.
247 * Returns 0 when we weren't able to find any time source
249 static uint64_t get_timer_bits(void)
251 uint64_t res = OPENSSL_rdtsc();
260 if (QueryPerformanceCounter(&t) != 0)
262 GetSystemTimeAsFileTime(&ft);
263 return TWO32TO64(ft.dwHighDateTime, ft.dwLowDateTime);
265 #elif defined(__sun) || defined(__hpux)
271 read_wall_time(&t, TIMEBASE_SZ);
272 return TWO32TO64(t.tb_high, t.tb_low);
276 # if defined(OSSL_POSIX_TIMER_OKAY)
281 # ifdef CLOCK_BOOTTIME
282 cid = CLOCK_BOOTTIME;
283 # elif defined(_POSIX_MONOTONIC_CLOCK)
284 cid = CLOCK_MONOTONIC;
286 cid = CLOCK_REALTIME;
289 if (clock_gettime(cid, &ts) == 0)
290 return TWO32TO64(ts.tv_sec, ts.tv_nsec);
293 # if defined(__unix__) \
294 || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
298 if (gettimeofday(&tv, NULL) == 0)
299 return TWO32TO64(tv.tv_sec, tv.tv_usec);
303 time_t t = time(NULL);
312 * Generate additional data that can be used for the drbg. The data does
313 * not need to contain entropy, but it's useful if it contains at least
314 * some bits that are unpredictable.
316 * Returns 0 on failure.
318 * On success it allocates a buffer at |*pout| and returns the length of
319 * the data. The buffer should get freed using OPENSSL_secure_clear_free().
321 size_t rand_drbg_get_additional_data(unsigned char **pout, size_t max_len)
324 CRYPTO_THREAD_ID thread_id;
326 #ifdef OPENSSL_SYS_UNIX
328 #elif defined(OPENSSL_SYS_WIN32)
333 pool = rand_pool_new(0, 0, max_len);
337 #ifdef OPENSSL_SYS_UNIX
339 rand_pool_add(pool, (unsigned char *)&pid, sizeof(pid), 0);
340 #elif defined(OPENSSL_SYS_WIN32)
341 pid = GetCurrentProcessId();
342 rand_pool_add(pool, (unsigned char *)&pid, sizeof(pid), 0);
345 thread_id = CRYPTO_THREAD_get_current_id();
347 rand_pool_add(pool, (unsigned char *)&thread_id, sizeof(thread_id), 0);
349 tbits = get_timer_bits();
351 rand_pool_add(pool, (unsigned char *)&tbits, sizeof(tbits), 0);
353 /* TODO: Use RDSEED? */
355 len = rand_pool_length(pool);
357 *pout = rand_pool_detach(pool);
358 rand_pool_free(pool);
364 * Implements the cleanup_entropy() callback (see RAND_DRBG_set_callbacks())
367 void rand_drbg_cleanup_entropy(RAND_DRBG *drbg,
368 unsigned char *out, size_t outlen)
370 OPENSSL_secure_clear_free(out, outlen);
378 DEFINE_RUN_ONCE_STATIC(do_rand_init)
382 #ifndef OPENSSL_NO_ENGINE
383 rand_engine_lock = CRYPTO_THREAD_lock_new();
384 ret &= rand_engine_lock != NULL;
386 rand_meth_lock = CRYPTO_THREAD_lock_new();
387 ret &= rand_meth_lock != NULL;
392 void rand_cleanup_int(void)
394 const RAND_METHOD *meth = default_RAND_meth;
396 if (meth != NULL && meth->cleanup != NULL)
398 RAND_set_rand_method(NULL);
399 #ifndef OPENSSL_NO_ENGINE
400 CRYPTO_THREAD_lock_free(rand_engine_lock);
402 CRYPTO_THREAD_lock_free(rand_meth_lock);
406 * RAND_poll() reseeds the default RNG using random input
408 * The random input is obtained from polling various entropy
409 * sources which depend on the operating system and are
410 * configurable via the --with-rand-seed configure option.
416 RAND_POOL *pool = NULL;
418 const RAND_METHOD *meth = RAND_get_rand_method();
420 if (meth == RAND_OpenSSL()) {
421 /* fill random pool and seed the master DRBG */
422 RAND_DRBG *drbg = RAND_DRBG_get0_master();
427 rand_drbg_lock(drbg);
428 ret = rand_drbg_restart(drbg, NULL, 0, 0);
429 rand_drbg_unlock(drbg);
434 /* fill random pool and seed the current legacy RNG */
435 pool = rand_pool_new(RAND_DRBG_STRENGTH,
436 RAND_DRBG_STRENGTH / 8,
437 DRBG_MINMAX_FACTOR * (RAND_DRBG_STRENGTH / 8));
441 if (rand_pool_acquire_entropy(pool) == 0)
444 if (meth->add == NULL
445 || meth->add(rand_pool_buffer(pool),
446 rand_pool_length(pool),
447 (rand_pool_entropy(pool) / 8.0)) == 0)
454 rand_pool_free(pool);
459 * The 'random pool' acts as a dumb container for collecting random
460 * input from various entropy sources. The pool has no knowledge about
461 * whether its randomness is fed into a legacy RAND_METHOD via RAND_add()
462 * or into a new style RAND_DRBG. It is the callers duty to 1) initialize the
463 * random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and
464 * 4) cleanup the random pool again.
466 * The random pool contains no locking mechanism because its scope and
467 * lifetime is intended to be restricted to a single stack frame.
469 struct rand_pool_st {
470 unsigned char *buffer; /* points to the beginning of the random pool */
471 size_t len; /* current number of random bytes contained in the pool */
473 size_t min_len; /* minimum number of random bytes requested */
474 size_t max_len; /* maximum number of random bytes (allocated buffer size) */
475 size_t entropy; /* current entropy count in bits */
476 size_t requested_entropy; /* requested entropy count in bits */
480 * Allocate memory and initialize a new random pool
483 RAND_POOL *rand_pool_new(int entropy, size_t min_len, size_t max_len)
485 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
488 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
492 pool->min_len = min_len;
493 pool->max_len = max_len;
495 pool->buffer = OPENSSL_secure_zalloc(pool->max_len);
496 if (pool->buffer == NULL) {
497 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
501 pool->requested_entropy = entropy;
511 * Free |pool|, securely erasing its buffer.
513 void rand_pool_free(RAND_POOL *pool)
518 OPENSSL_secure_clear_free(pool->buffer, pool->max_len);
523 * Return the |pool|'s buffer to the caller (readonly).
525 const unsigned char *rand_pool_buffer(RAND_POOL *pool)
531 * Return the |pool|'s entropy to the caller.
533 size_t rand_pool_entropy(RAND_POOL *pool)
535 return pool->entropy;
539 * Return the |pool|'s buffer length to the caller.
541 size_t rand_pool_length(RAND_POOL *pool)
547 * Detach the |pool| buffer and return it to the caller.
548 * It's the responsibility of the caller to free the buffer
549 * using OPENSSL_secure_clear_free().
551 unsigned char *rand_pool_detach(RAND_POOL *pool)
553 unsigned char *ret = pool->buffer;
560 * If every byte of the input contains |entropy_per_bytes| bits of entropy,
561 * how many bytes does one need to obtain at least |bits| bits of entropy?
563 #define ENTROPY_TO_BYTES(bits, entropy_per_bytes) \
564 (((bits) + ((entropy_per_bytes) - 1))/(entropy_per_bytes))
568 * Checks whether the |pool|'s entropy is available to the caller.
569 * This is the case when entropy count and buffer length are high enough.
572 * |entropy| if the entropy count and buffer size is large enough
575 size_t rand_pool_entropy_available(RAND_POOL *pool)
577 if (pool->entropy < pool->requested_entropy)
580 if (pool->len < pool->min_len)
583 return pool->entropy;
587 * Returns the (remaining) amount of entropy needed to fill
591 size_t rand_pool_entropy_needed(RAND_POOL *pool)
593 if (pool->entropy < pool->requested_entropy)
594 return pool->requested_entropy - pool->entropy;
600 * Returns the number of bytes needed to fill the pool, assuming
601 * the input has 'entropy_per_byte' entropy bits per byte.
602 * In case of an error, 0 is returned.
605 size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_per_byte)
608 size_t entropy_needed = rand_pool_entropy_needed(pool);
610 if (entropy_per_byte < 1 || entropy_per_byte > 8) {
611 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_ARGUMENT_OUT_OF_RANGE);
615 bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_per_byte);
617 if (bytes_needed > pool->max_len - pool->len) {
618 /* not enough space left */
619 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_RANDOM_POOL_OVERFLOW);
623 if (pool->len < pool->min_len &&
624 bytes_needed < pool->min_len - pool->len)
625 /* to meet the min_len requirement */
626 bytes_needed = pool->min_len - pool->len;
631 /* Returns the remaining number of bytes available */
632 size_t rand_pool_bytes_remaining(RAND_POOL *pool)
634 return pool->max_len - pool->len;
638 * Add random bytes to the random pool.
640 * It is expected that the |buffer| contains |len| bytes of
641 * random input which contains at least |entropy| bits of
644 * Return available amount of entropy after this operation.
645 * (see rand_pool_entropy_available(pool))
647 size_t rand_pool_add(RAND_POOL *pool,
648 const unsigned char *buffer, size_t len, size_t entropy)
650 if (len > pool->max_len - pool->len) {
651 RANDerr(RAND_F_RAND_POOL_ADD, RAND_R_ENTROPY_INPUT_TOO_LONG);
656 memcpy(pool->buffer + pool->len, buffer, len);
658 pool->entropy += entropy;
661 return rand_pool_entropy_available(pool);
665 * Start to add random bytes to the random pool in-place.
667 * Reserves the next |len| bytes for adding random bytes in-place
668 * and returns a pointer to the buffer.
669 * The caller is allowed to copy up to |len| bytes into the buffer.
670 * If |len| == 0 this is considered a no-op and a NULL pointer
671 * is returned without producing an error message.
673 * After updating the buffer, rand_pool_add_end() needs to be called
674 * to finish the udpate operation (see next comment).
676 unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len)
681 if (len > pool->max_len - pool->len) {
682 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, RAND_R_RANDOM_POOL_OVERFLOW);
686 return pool->buffer + pool->len;
690 * Finish to add random bytes to the random pool in-place.
692 * Finishes an in-place update of the random pool started by
693 * rand_pool_add_begin() (see previous comment).
694 * It is expected that |len| bytes of random input have been added
695 * to the buffer which contain at least |entropy| bits of randomness.
696 * It is allowed to add less bytes than originally reserved.
698 size_t rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy)
700 if (len > pool->max_len - pool->len) {
701 RANDerr(RAND_F_RAND_POOL_ADD_END, RAND_R_RANDOM_POOL_OVERFLOW);
707 pool->entropy += entropy;
710 return rand_pool_entropy_available(pool);
713 int RAND_set_rand_method(const RAND_METHOD *meth)
715 if (!RUN_ONCE(&rand_init, do_rand_init))
718 CRYPTO_THREAD_write_lock(rand_meth_lock);
719 #ifndef OPENSSL_NO_ENGINE
720 ENGINE_finish(funct_ref);
723 default_RAND_meth = meth;
724 CRYPTO_THREAD_unlock(rand_meth_lock);
728 const RAND_METHOD *RAND_get_rand_method(void)
730 const RAND_METHOD *tmp_meth = NULL;
732 if (!RUN_ONCE(&rand_init, do_rand_init))
735 CRYPTO_THREAD_write_lock(rand_meth_lock);
736 if (default_RAND_meth == NULL) {
737 #ifndef OPENSSL_NO_ENGINE
740 /* If we have an engine that can do RAND, use it. */
741 if ((e = ENGINE_get_default_RAND()) != NULL
742 && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
744 default_RAND_meth = tmp_meth;
747 default_RAND_meth = &rand_meth;
750 default_RAND_meth = &rand_meth;
753 tmp_meth = default_RAND_meth;
754 CRYPTO_THREAD_unlock(rand_meth_lock);
758 #ifndef OPENSSL_NO_ENGINE
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(unsigned char *buf, int num)
807 const RAND_METHOD *meth = RAND_get_rand_method();
811 if (meth != RAND_OpenSSL())
812 return RAND_bytes(buf, num);
814 drbg = RAND_DRBG_get0_private();
818 /* We have to lock the DRBG before generating bits from it. */
819 rand_drbg_lock(drbg);
820 ret = RAND_DRBG_bytes(drbg, buf, num);
821 rand_drbg_unlock(drbg);
825 int RAND_bytes(unsigned char *buf, int num)
827 const RAND_METHOD *meth = RAND_get_rand_method();
829 if (meth->bytes != NULL)
830 return meth->bytes(buf, num);
831 RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
835 #if OPENSSL_API_COMPAT < 0x10100000L
836 int RAND_pseudo_bytes(unsigned char *buf, int num)
838 const RAND_METHOD *meth = RAND_get_rand_method();
840 if (meth->pseudorand != NULL)
841 return meth->pseudorand(buf, num);
846 int RAND_status(void)
848 const RAND_METHOD *meth = RAND_get_rand_method();
850 if (meth->status != NULL)
851 return meth->status();