/* * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the OpenSSL license (the "License"). You may not use * this file except in compliance with the License. You can obtain a copy * in the file LICENSE in the source distribution or at * https://www.openssl.org/source/license.html */ #include #include #include "internal/cryptlib.h" #include #include "internal/rand_int.h" #include #include "internal/thread_once.h" #include "rand_lcl.h" #include "e_os.h" #ifndef OPENSSL_NO_ENGINE /* non-NULL if default_RAND_meth is ENGINE-provided */ static ENGINE *funct_ref; static CRYPTO_RWLOCK *rand_engine_lock; #endif static CRYPTO_RWLOCK *rand_meth_lock; static const RAND_METHOD *default_RAND_meth; static CRYPTO_ONCE rand_init = CRYPTO_ONCE_STATIC_INIT; int rand_fork_count; static CRYPTO_RWLOCK *rand_nonce_lock; static int rand_nonce_count; static int rand_cleaning_up = 0; #ifdef OPENSSL_RAND_SEED_RDTSC /* * IMPORTANT NOTE: It is not currently possible to use this code * because we are not sure about the amount of randomness it provides. * Some SP900 tests have been run, but there is internal skepticism. * So for now this code is not used. */ # error "RDTSC enabled? Should not be possible!" /* * Acquire entropy from high-speed clock * * Since we get some randomness from the low-order bits of the * high-speed clock, it can help. * * Returns the total entropy count, if it exceeds the requested * entropy count. Otherwise, returns an entropy count of 0. */ size_t rand_acquire_entropy_from_tsc(RAND_POOL *pool) { unsigned char c; int i; if ((OPENSSL_ia32cap_P[0] & (1 << 4)) != 0) { for (i = 0; i < TSC_READ_COUNT; i++) { c = (unsigned char)(OPENSSL_rdtsc() & 0xFF); rand_pool_add(pool, &c, 1, 4); } } return rand_pool_entropy_available(pool); } #endif #ifdef OPENSSL_RAND_SEED_RDCPU size_t OPENSSL_ia32_rdseed_bytes(unsigned char *buf, size_t len); size_t OPENSSL_ia32_rdrand_bytes(unsigned char *buf, size_t len); extern unsigned int OPENSSL_ia32cap_P[]; /* * Acquire entropy using Intel-specific cpu instructions * * Uses the RDSEED instruction if available, otherwise uses * RDRAND if available. * * For the differences between RDSEED and RDRAND, and why RDSEED * is the preferred choice, see https://goo.gl/oK3KcN * * Returns the total entropy count, if it exceeds the requested * entropy count. Otherwise, returns an entropy count of 0. */ size_t rand_acquire_entropy_from_cpu(RAND_POOL *pool) { size_t bytes_needed; unsigned char *buffer; bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/); if (bytes_needed > 0) { buffer = rand_pool_add_begin(pool, bytes_needed); if (buffer != NULL) { /* Whichever comes first, use RDSEED, RDRAND or nothing */ if ((OPENSSL_ia32cap_P[2] & (1 << 18)) != 0) { if (OPENSSL_ia32_rdseed_bytes(buffer, bytes_needed) == bytes_needed) { rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed); } } else if ((OPENSSL_ia32cap_P[1] & (1 << (62 - 32))) != 0) { if (OPENSSL_ia32_rdrand_bytes(buffer, bytes_needed) == bytes_needed) { rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed); } } else { rand_pool_add_end(pool, 0, 0); } } } return rand_pool_entropy_available(pool); } #endif /* * Implements the get_entropy() callback (see RAND_DRBG_set_callbacks()) * * If the DRBG has a parent, then the required amount of entropy input * is fetched using the parent's RAND_DRBG_generate(). * * Otherwise, the entropy is polled from the system entropy sources * using rand_pool_acquire_entropy(). * * If a random pool has been added to the DRBG using RAND_add(), then * its entropy will be used up first. */ size_t rand_drbg_get_entropy(RAND_DRBG *drbg, unsigned char **pout, int entropy, size_t min_len, size_t max_len, int prediction_resistance) { size_t ret = 0; size_t entropy_available = 0; RAND_POOL *pool; if (drbg->parent && drbg->strength > drbg->parent->strength) { /* * We currently don't support the algorithm from NIST SP 800-90C * 10.1.2 to use a weaker DRBG as source */ RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY, RAND_R_PARENT_STRENGTH_TOO_WEAK); return 0; } if (drbg->pool != NULL) { pool = drbg->pool; pool->entropy_requested = entropy; } else { pool = rand_pool_new(entropy, min_len, max_len); if (pool == NULL) return 0; } if (drbg->parent) { size_t bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/); unsigned char *buffer = rand_pool_add_begin(pool, bytes_needed); if (buffer != NULL) { size_t bytes = 0; /* * Get random from parent, include our state as additional input. * Our lock is already held, but we need to lock our parent before * generating bits from it. (Note: taking the lock will be a no-op * if locking if drbg->parent->lock == NULL.) */ rand_drbg_lock(drbg->parent); if (RAND_DRBG_generate(drbg->parent, buffer, bytes_needed, prediction_resistance, NULL, 0) != 0) bytes = bytes_needed; drbg->reseed_next_counter = tsan_load(&drbg->parent->reseed_prop_counter); rand_drbg_unlock(drbg->parent); rand_pool_add_end(pool, bytes, 8 * bytes); entropy_available = rand_pool_entropy_available(pool); } } else { if (prediction_resistance) { /* * We don't have any entropy sources that comply with the NIST * standard to provide prediction resistance (see NIST SP 800-90C, * Section 5.4). */ RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY, RAND_R_PREDICTION_RESISTANCE_NOT_SUPPORTED); goto err; } /* Get entropy by polling system entropy sources. */ entropy_available = rand_pool_acquire_entropy(pool); } if (entropy_available > 0) { ret = rand_pool_length(pool); *pout = rand_pool_detach(pool); } err: if (drbg->pool == NULL) rand_pool_free(pool); return ret; } /* * Implements the cleanup_entropy() callback (see RAND_DRBG_set_callbacks()) * */ void rand_drbg_cleanup_entropy(RAND_DRBG *drbg, unsigned char *out, size_t outlen) { if (drbg->pool == NULL) OPENSSL_secure_clear_free(out, outlen); } /* * Implements the get_nonce() callback (see RAND_DRBG_set_callbacks()) * */ size_t rand_drbg_get_nonce(RAND_DRBG *drbg, unsigned char **pout, int entropy, size_t min_len, size_t max_len) { size_t ret = 0; RAND_POOL *pool; struct { void * instance; int count; } data = { 0 }; pool = rand_pool_new(0, min_len, max_len); if (pool == NULL) return 0; if (rand_pool_add_nonce_data(pool) == 0) goto err; data.instance = drbg; CRYPTO_atomic_add(&rand_nonce_count, 1, &data.count, rand_nonce_lock); if (rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0) == 0) goto err; ret = rand_pool_length(pool); *pout = rand_pool_detach(pool); err: rand_pool_free(pool); return ret; } /* * Implements the cleanup_nonce() callback (see RAND_DRBG_set_callbacks()) * */ void rand_drbg_cleanup_nonce(RAND_DRBG *drbg, unsigned char *out, size_t outlen) { OPENSSL_secure_clear_free(out, outlen); } /* * Generate additional data that can be used for the drbg. The data does * not need to contain entropy, but it's useful if it contains at least * some bits that are unpredictable. * * Returns 0 on failure. * * On success it allocates a buffer at |*pout| and returns the length of * the data. The buffer should get freed using OPENSSL_secure_clear_free(). */ size_t rand_drbg_get_additional_data(unsigned char **pout, size_t max_len) { size_t ret = 0; RAND_POOL *pool; pool = rand_pool_new(0, 0, max_len); if (pool == NULL) return 0; if (rand_pool_add_additional_data(pool) == 0) goto err; ret = rand_pool_length(pool); *pout = rand_pool_detach(pool); err: rand_pool_free(pool); return ret; } void rand_drbg_cleanup_additional_data(unsigned char *out, size_t outlen) { OPENSSL_secure_clear_free(out, outlen); } void rand_fork(void) { rand_fork_count++; } DEFINE_RUN_ONCE_STATIC(do_rand_init) { #ifndef OPENSSL_NO_ENGINE rand_engine_lock = CRYPTO_THREAD_lock_new(); if (rand_engine_lock == NULL) return 0; #endif rand_meth_lock = CRYPTO_THREAD_lock_new(); if (rand_meth_lock == NULL) goto err1; rand_nonce_lock = CRYPTO_THREAD_lock_new(); if (rand_nonce_lock == NULL) goto err2; if (!rand_cleaning_up && !rand_pool_init()) goto err3; return 1; err3: rand_pool_cleanup(); err2: CRYPTO_THREAD_lock_free(rand_meth_lock); rand_meth_lock = NULL; err1: #ifndef OPENSSL_NO_ENGINE CRYPTO_THREAD_lock_free(rand_engine_lock); rand_engine_lock = NULL; #endif return 0; } void rand_cleanup_int(void) { const RAND_METHOD *meth = default_RAND_meth; rand_cleaning_up = 1; if (meth != NULL && meth->cleanup != NULL) meth->cleanup(); RAND_set_rand_method(NULL); rand_pool_cleanup(); #ifndef OPENSSL_NO_ENGINE CRYPTO_THREAD_lock_free(rand_engine_lock); rand_engine_lock = NULL; #endif CRYPTO_THREAD_lock_free(rand_meth_lock); rand_meth_lock = NULL; CRYPTO_THREAD_lock_free(rand_nonce_lock); rand_nonce_lock = NULL; } /* * RAND_close_seed_files() ensures that any seed file decriptors are * closed after use. */ void RAND_keep_random_devices_open(int keep) { rand_pool_keep_random_devices_open(keep); } /* * RAND_poll() reseeds the default RNG using random input * * The random input is obtained from polling various entropy * sources which depend on the operating system and are * configurable via the --with-rand-seed configure option. */ int RAND_poll(void) { int ret = 0; RAND_POOL *pool = NULL; const RAND_METHOD *meth = RAND_get_rand_method(); if (meth == RAND_OpenSSL()) { /* fill random pool and seed the master DRBG */ RAND_DRBG *drbg = RAND_DRBG_get0_master(); if (drbg == NULL) return 0; rand_drbg_lock(drbg); ret = rand_drbg_restart(drbg, NULL, 0, 0); rand_drbg_unlock(drbg); return ret; } else { /* fill random pool and seed the current legacy RNG */ pool = rand_pool_new(RAND_DRBG_STRENGTH, RAND_DRBG_STRENGTH / 8, RAND_POOL_MAX_LENGTH); if (pool == NULL) return 0; if (rand_pool_acquire_entropy(pool) == 0) goto err; if (meth->add == NULL || meth->add(rand_pool_buffer(pool), rand_pool_length(pool), (rand_pool_entropy(pool) / 8.0)) == 0) goto err; ret = 1; } err: rand_pool_free(pool); return ret; } /* * Allocate memory and initialize a new random pool */ RAND_POOL *rand_pool_new(int entropy_requested, size_t min_len, size_t max_len) { RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool)); if (pool == NULL) { RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE); return NULL; } pool->min_len = min_len; pool->max_len = (max_len > RAND_POOL_MAX_LENGTH) ? RAND_POOL_MAX_LENGTH : max_len; pool->buffer = OPENSSL_secure_zalloc(pool->max_len); if (pool->buffer == NULL) { RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE); goto err; } pool->entropy_requested = entropy_requested; return pool; err: OPENSSL_free(pool); return NULL; } /* * Attach new random pool to the given buffer * * This function is intended to be used only for feeding random data * provided by RAND_add() and RAND_seed() into the DRBG. */ RAND_POOL *rand_pool_attach(const unsigned char *buffer, size_t len, size_t entropy) { RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool)); if (pool == NULL) { RANDerr(RAND_F_RAND_POOL_ATTACH, ERR_R_MALLOC_FAILURE); return NULL; } /* * The const needs to be cast away, but attached buffers will not be * modified (in contrary to allocated buffers which are zeroed and * freed in the end). */ pool->buffer = (unsigned char *) buffer; pool->len = len; pool->attached = 1; pool->min_len = pool->max_len = pool->len; pool->entropy = entropy; return pool; } /* * Free |pool|, securely erasing its buffer. */ void rand_pool_free(RAND_POOL *pool) { if (pool == NULL) return; /* * Although it would be advisable from a cryptographical viewpoint, * we are not allowed to clear attached buffers, since they are passed * to rand_pool_attach() as `const unsigned char*`. * (see corresponding comment in rand_pool_attach()). */ if (!pool->attached) OPENSSL_secure_clear_free(pool->buffer, pool->max_len); OPENSSL_free(pool); } /* * Return the |pool|'s buffer to the caller (readonly). */ const unsigned char *rand_pool_buffer(RAND_POOL *pool) { return pool->buffer; } /* * Return the |pool|'s entropy to the caller. */ size_t rand_pool_entropy(RAND_POOL *pool) { return pool->entropy; } /* * Return the |pool|'s buffer length to the caller. */ size_t rand_pool_length(RAND_POOL *pool) { return pool->len; } /* * Detach the |pool| buffer and return it to the caller. * It's the responsibility of the caller to free the buffer * using OPENSSL_secure_clear_free(). */ unsigned char *rand_pool_detach(RAND_POOL *pool) { unsigned char *ret = pool->buffer; pool->buffer = NULL; pool->len = 0; pool->entropy = 0; return ret; } /* * If |entropy_factor| bits contain 1 bit of entropy, how many bytes does one * need to obtain at least |bits| bits of entropy? */ #define ENTROPY_TO_BYTES(bits, entropy_factor) \ (((bits) * (entropy_factor) + 7) / 8) /* * Checks whether the |pool|'s entropy is available to the caller. * This is the case when entropy count and buffer length are high enough. * Returns * * |entropy| if the entropy count and buffer size is large enough * 0 otherwise */ size_t rand_pool_entropy_available(RAND_POOL *pool) { if (pool->entropy < pool->entropy_requested) return 0; if (pool->len < pool->min_len) return 0; return pool->entropy; } /* * Returns the (remaining) amount of entropy needed to fill * the random pool. */ size_t rand_pool_entropy_needed(RAND_POOL *pool) { if (pool->entropy < pool->entropy_requested) return pool->entropy_requested - pool->entropy; return 0; } /* * Returns the number of bytes needed to fill the pool, assuming * the input has 1 / |entropy_factor| entropy bits per data bit. * In case of an error, 0 is returned. */ size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_factor) { size_t bytes_needed; size_t entropy_needed = rand_pool_entropy_needed(pool); if (entropy_factor < 1) { RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_ARGUMENT_OUT_OF_RANGE); return 0; } bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_factor); if (bytes_needed > pool->max_len - pool->len) { /* not enough space left */ RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_RANDOM_POOL_OVERFLOW); return 0; } if (pool->len < pool->min_len && bytes_needed < pool->min_len - pool->len) /* to meet the min_len requirement */ bytes_needed = pool->min_len - pool->len; return bytes_needed; } /* Returns the remaining number of bytes available */ size_t rand_pool_bytes_remaining(RAND_POOL *pool) { return pool->max_len - pool->len; } /* * Add random bytes to the random pool. * * It is expected that the |buffer| contains |len| bytes of * random input which contains at least |entropy| bits of * randomness. * * Returns 1 if the added amount is adequate, otherwise 0 */ int rand_pool_add(RAND_POOL *pool, const unsigned char *buffer, size_t len, size_t entropy) { if (len > pool->max_len - pool->len) { RANDerr(RAND_F_RAND_POOL_ADD, RAND_R_ENTROPY_INPUT_TOO_LONG); return 0; } if (len > 0) { memcpy(pool->buffer + pool->len, buffer, len); pool->len += len; pool->entropy += entropy; } return 1; } /* * Start to add random bytes to the random pool in-place. * * Reserves the next |len| bytes for adding random bytes in-place * and returns a pointer to the buffer. * The caller is allowed to copy up to |len| bytes into the buffer. * If |len| == 0 this is considered a no-op and a NULL pointer * is returned without producing an error message. * * After updating the buffer, rand_pool_add_end() needs to be called * to finish the udpate operation (see next comment). */ unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len) { if (len == 0) return NULL; if (len > pool->max_len - pool->len) { RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, RAND_R_RANDOM_POOL_OVERFLOW); return NULL; } return pool->buffer + pool->len; } /* * Finish to add random bytes to the random pool in-place. * * Finishes an in-place update of the random pool started by * rand_pool_add_begin() (see previous comment). * It is expected that |len| bytes of random input have been added * to the buffer which contain at least |entropy| bits of randomness. * It is allowed to add less bytes than originally reserved. */ int rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy) { if (len > pool->max_len - pool->len) { RANDerr(RAND_F_RAND_POOL_ADD_END, RAND_R_RANDOM_POOL_OVERFLOW); return 0; } if (len > 0) { pool->len += len; pool->entropy += entropy; } return 1; } int RAND_set_rand_method(const RAND_METHOD *meth) { if (!RUN_ONCE(&rand_init, do_rand_init)) return 0; CRYPTO_THREAD_write_lock(rand_meth_lock); #ifndef OPENSSL_NO_ENGINE ENGINE_finish(funct_ref); funct_ref = NULL; #endif default_RAND_meth = meth; CRYPTO_THREAD_unlock(rand_meth_lock); return 1; } const RAND_METHOD *RAND_get_rand_method(void) { const RAND_METHOD *tmp_meth = NULL; if (!RUN_ONCE(&rand_init, do_rand_init)) return NULL; CRYPTO_THREAD_write_lock(rand_meth_lock); if (default_RAND_meth == NULL) { #ifndef OPENSSL_NO_ENGINE ENGINE *e; /* If we have an engine that can do RAND, use it. */ if ((e = ENGINE_get_default_RAND()) != NULL && (tmp_meth = ENGINE_get_RAND(e)) != NULL) { funct_ref = e; default_RAND_meth = tmp_meth; } else { ENGINE_finish(e); default_RAND_meth = &rand_meth; } #else default_RAND_meth = &rand_meth; #endif } tmp_meth = default_RAND_meth; CRYPTO_THREAD_unlock(rand_meth_lock); return tmp_meth; } #ifndef OPENSSL_NO_ENGINE int RAND_set_rand_engine(ENGINE *engine) { const RAND_METHOD *tmp_meth = NULL; if (!RUN_ONCE(&rand_init, do_rand_init)) return 0; if (engine != NULL) { if (!ENGINE_init(engine)) return 0; tmp_meth = ENGINE_get_RAND(engine); if (tmp_meth == NULL) { ENGINE_finish(engine); return 0; } } CRYPTO_THREAD_write_lock(rand_engine_lock); /* This function releases any prior ENGINE so call it first */ RAND_set_rand_method(tmp_meth); funct_ref = engine; CRYPTO_THREAD_unlock(rand_engine_lock); return 1; } #endif void RAND_seed(const void *buf, int num) { const RAND_METHOD *meth = RAND_get_rand_method(); if (meth->seed != NULL) meth->seed(buf, num); } void RAND_add(const void *buf, int num, double randomness) { const RAND_METHOD *meth = RAND_get_rand_method(); if (meth->add != NULL) meth->add(buf, num, randomness); } /* * This function is not part of RAND_METHOD, so if we're not using * the default method, then just call RAND_bytes(). Otherwise make * sure we're instantiated and use the private DRBG. */ int RAND_priv_bytes(unsigned char *buf, int num) { const RAND_METHOD *meth = RAND_get_rand_method(); RAND_DRBG *drbg; int ret; if (meth != RAND_OpenSSL()) return RAND_bytes(buf, num); drbg = RAND_DRBG_get0_private(); if (drbg == NULL) return 0; ret = RAND_DRBG_bytes(drbg, buf, num); return ret; } int RAND_bytes(unsigned char *buf, int num) { const RAND_METHOD *meth = RAND_get_rand_method(); if (meth->bytes != NULL) return meth->bytes(buf, num); RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED); return -1; } #if OPENSSL_API_COMPAT < 0x10100000L int RAND_pseudo_bytes(unsigned char *buf, int num) { const RAND_METHOD *meth = RAND_get_rand_method(); if (meth->pseudorand != NULL) return meth->pseudorand(buf, num); return -1; } #endif int RAND_status(void) { const RAND_METHOD *meth = RAND_get_rand_method(); if (meth->status != NULL) return meth->status(); return 0; }