/* * Copyright 2011-2017 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 #include #include "rand_lcl.h" #include "internal/thread_once.h" #include "internal/rand_int.h" static RAND_DRBG rand_drbg; /* The default global DRBG. */ static RAND_DRBG priv_drbg; /* The global private-key DRBG. */ /* NIST SP 800-90A DRBG recommends the use of a personalization string. */ static const char ossl_pers_string[] = "OpenSSL NIST SP 800-90A DRBG"; /* * Support framework for NIST SP 800-90A DRBG, AES-CTR mode. * The RAND_DRBG is OpenSSL's pointer to an instance of the DRBG. * * The OpenSSL model is to have new and free functions, and that new * does all initialization. That is not the NIST model, which has * instantiation and un-instantiate, and re-use within a new/free * lifecycle. (No doubt this comes from the desire to support hardware * DRBG, where allocation of resources on something like an HSM is * a much bigger deal than just re-setting an allocated resource.) */ static CRYPTO_ONCE rand_drbg_init = CRYPTO_ONCE_STATIC_INIT; static int drbg_setup(RAND_DRBG *drbg, const char *name); /* * Set/initialize |drbg| to be of type |nid|, with optional |flags|. * Return -2 if the type is not supported, 1 on success and -1 on * failure. */ int RAND_DRBG_set(RAND_DRBG *drbg, int nid, unsigned int flags) { int ret = 1; drbg->state = DRBG_UNINITIALISED; drbg->flags = flags; drbg->nid = nid; switch (nid) { default: RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_UNSUPPORTED_DRBG_TYPE); return -2; case 0: /* Uninitialized; that's okay. */ return 1; case NID_aes_128_ctr: case NID_aes_192_ctr: case NID_aes_256_ctr: ret = ctr_init(drbg); break; } if (ret < 0) RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_ERROR_INITIALISING_DRBG); return ret; } /* * Allocate memory and initialize a new DRBG. The |parent|, if not * NULL, will be used to auto-seed this RAND_DRBG as needed. */ RAND_DRBG *RAND_DRBG_new(int type, unsigned int flags, RAND_DRBG *parent) { RAND_DRBG *drbg = OPENSSL_zalloc(sizeof(*drbg)); if (drbg == NULL) { RANDerr(RAND_F_RAND_DRBG_NEW, ERR_R_MALLOC_FAILURE); goto err; } drbg->fork_count = rand_fork_count; drbg->parent = parent; if (RAND_DRBG_set(drbg, type, flags) < 0) goto err; if (parent != NULL) { if (!RAND_DRBG_set_callbacks(drbg, rand_drbg_get_entropy, rand_drbg_cleanup_entropy, NULL, NULL)) goto err; } return drbg; err: OPENSSL_free(drbg); return NULL; } /* * Uninstantiate |drbg| and free all memory. */ void RAND_DRBG_free(RAND_DRBG *drbg) { if (drbg == NULL) return; ctr_uninstantiate(drbg); CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DRBG, drbg, &drbg->ex_data); OPENSSL_clear_free(drbg, sizeof(*drbg)); } /* * Instantiate |drbg|, after it has been initialized. Use |pers| and * |perslen| as prediction-resistance input. * * Requires that drbg->lock is already locked for write, if non-null. */ int RAND_DRBG_instantiate(RAND_DRBG *drbg, const unsigned char *pers, size_t perslen) { unsigned char *nonce = NULL, *entropy = NULL; size_t noncelen = 0, entropylen = 0; if (perslen > drbg->max_perslen) { RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_PERSONALISATION_STRING_TOO_LONG); goto end; } if (drbg->state != DRBG_UNINITIALISED) { RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, drbg->state == DRBG_ERROR ? RAND_R_IN_ERROR_STATE : RAND_R_ALREADY_INSTANTIATED); goto end; } drbg->state = DRBG_ERROR; if (drbg->get_entropy != NULL) entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength, drbg->min_entropylen, drbg->max_entropylen); if (entropylen < drbg->min_entropylen || entropylen > drbg->max_entropylen) { RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_ENTROPY); goto end; } if (drbg->max_noncelen > 0 && drbg->get_nonce != NULL) { noncelen = drbg->get_nonce(drbg, &nonce, drbg->strength / 2, drbg->min_noncelen, drbg->max_noncelen); if (noncelen < drbg->min_noncelen || noncelen > drbg->max_noncelen) { RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_NONCE); goto end; } } if (!ctr_instantiate(drbg, entropy, entropylen, nonce, noncelen, pers, perslen)) { RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_INSTANTIATING_DRBG); goto end; } drbg->state = DRBG_READY; drbg->reseed_counter = 1; end: if (entropy != NULL && drbg->cleanup_entropy != NULL) drbg->cleanup_entropy(drbg, entropy, entropylen); if (nonce != NULL && drbg->cleanup_nonce!= NULL ) drbg->cleanup_nonce(drbg, nonce, noncelen); if (drbg->pool != NULL) { if (drbg->state == DRBG_READY) { RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_ENTROPY_POOL_WAS_IGNORED); drbg->state = DRBG_ERROR; } RAND_POOL_free(drbg->pool); drbg->pool = NULL; } if (drbg->state == DRBG_READY) return 1; return 0; } /* * Uninstantiate |drbg|. Must be instantiated before it can be used. * * Requires that drbg->lock is already locked for write, if non-null. */ int RAND_DRBG_uninstantiate(RAND_DRBG *drbg) { int ret = ctr_uninstantiate(drbg); OPENSSL_cleanse(&drbg->ctr, sizeof(drbg->ctr)); drbg->state = DRBG_UNINITIALISED; return ret; } /* * Reseed |drbg|, mixing in the specified data * * Requires that drbg->lock is already locked for write, if non-null. */ int RAND_DRBG_reseed(RAND_DRBG *drbg, const unsigned char *adin, size_t adinlen) { unsigned char *entropy = NULL; size_t entropylen = 0; if (drbg->state == DRBG_ERROR) { RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_IN_ERROR_STATE); return 0; } if (drbg->state == DRBG_UNINITIALISED) { RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_NOT_INSTANTIATED); return 0; } if (adin == NULL) adinlen = 0; else if (adinlen > drbg->max_adinlen) { RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ADDITIONAL_INPUT_TOO_LONG); return 0; } drbg->state = DRBG_ERROR; if (drbg->get_entropy != NULL) entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength, drbg->min_entropylen, drbg->max_entropylen); if (entropylen < drbg->min_entropylen || entropylen > drbg->max_entropylen) { RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ERROR_RETRIEVING_ENTROPY); goto end; } if (!ctr_reseed(drbg, entropy, entropylen, adin, adinlen)) goto end; drbg->state = DRBG_READY; drbg->reseed_counter = 1; end: if (entropy != NULL && drbg->cleanup_entropy != NULL) drbg->cleanup_entropy(drbg, entropy, entropylen); if (drbg->state == DRBG_READY) return 1; return 0; } /* * Restart |drbg|, using the specified entropy or additional input * * Tries its best to get the drbg instantiated by all means, * regardless of its current state. * * Optionally, a |buffer| of |len| random bytes can be passed, * which is assumed to contain at least |entropy| bits of entropy. * * If |entropy| > 0, the buffer content is used as entropy input. * * If |entropy| == 0, the buffer content is used as additional input * * Returns 1 on success, 0 on failure. * * This function is used internally only. */ int rand_drbg_restart(RAND_DRBG *drbg, const unsigned char *buffer, size_t len, size_t entropy) { int reseeded = 0; const unsigned char *adin = NULL; size_t adinlen = 0; if (drbg->pool != NULL) { RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR); RAND_POOL_free(drbg->pool); drbg->pool = NULL; } if (buffer != NULL) { if (entropy > 0) { if (drbg->max_entropylen < len) { RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_ENTROPY_INPUT_TOO_LONG); return 0; } if (entropy > 8 * len) { RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_ENTROPY_OUT_OF_RANGE); return 0; } /* will be picked up by the rand_drbg_get_entropy() callback */ drbg->pool = RAND_POOL_new(entropy, len, len); if (drbg->pool == NULL) return 0; RAND_POOL_add(drbg->pool, buffer, len, entropy); } else { if (drbg->max_adinlen < len) { RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_ADDITIONAL_INPUT_TOO_LONG); return 0; } adin = buffer; adinlen = len; } } /* repair error state */ if (drbg->state == DRBG_ERROR) RAND_DRBG_uninstantiate(drbg); /* repair uninitialized state */ if (drbg->state == DRBG_UNINITIALISED) { drbg_setup(drbg, NULL); /* already reseeded. prevent second reseeding below */ reseeded = (drbg->state == DRBG_READY); } /* refresh current state if entropy or additional input has been provided */ if (drbg->state == DRBG_READY) { if (adin != NULL) { /* * mix in additional input without reseeding * * Similar to RAND_DRBG_reseed(), but the provided additional * data |adin| is mixed into the current state without pulling * entropy from the trusted entropy source using get_entropy(). * This is not a reseeding in the strict sense of NIST SP 800-90A. */ ctr_reseed(drbg, adin, adinlen, NULL, 0); } else if (reseeded == 0) { /* do a full reseeding if it has not been done yet above */ RAND_DRBG_reseed(drbg, NULL, 0); } } /* check whether a given entropy pool was cleared properly during reseed */ if (drbg->pool != NULL) { drbg->state = DRBG_ERROR; RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR); RAND_POOL_free(drbg->pool); drbg->pool = NULL; return 0; } return drbg->state == DRBG_READY; } /* * Generate |outlen| bytes into the buffer at |out|. Reseed if we need * to or if |prediction_resistance| is set. Additional input can be * sent in |adin| and |adinlen|. * * Requires that drbg->lock is already locked for write, if non-null. * * Returns 1 on success, 0 on failure. * */ int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen, int prediction_resistance, const unsigned char *adin, size_t adinlen) { int reseed_required = 0; if (drbg->state != DRBG_READY) { /* try to recover from previous errors */ rand_drbg_restart(drbg, NULL, 0, 0); if (drbg->state == DRBG_ERROR) { RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_IN_ERROR_STATE); return 0; } if (drbg->state == DRBG_UNINITIALISED) { RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_NOT_INSTANTIATED); return 0; } } if (outlen > drbg->max_request) { RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_REQUEST_TOO_LARGE_FOR_DRBG); return 0; } if (adinlen > drbg->max_adinlen) { RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_ADDITIONAL_INPUT_TOO_LONG); return 0; } if (drbg->fork_count != rand_fork_count) { drbg->fork_count = rand_fork_count; reseed_required = 1; } if (drbg->reseed_counter >= drbg->reseed_interval) reseed_required = 1; if (reseed_required || prediction_resistance) { if (!RAND_DRBG_reseed(drbg, adin, adinlen)) { RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_RESEED_ERROR); return 0; } adin = NULL; adinlen = 0; } if (!ctr_generate(drbg, out, outlen, adin, adinlen)) { drbg->state = DRBG_ERROR; RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_GENERATE_ERROR); return 0; } drbg->reseed_counter++; return 1; } /* * Set the RAND_DRBG callbacks for obtaining entropy and nonce. * * In the following, the signature and the semantics of the * get_entropy() and cleanup_entropy() callbacks are explained. * * GET_ENTROPY * * size_t get_entropy(RAND_DRBG *ctx, * unsigned char **pout, * int entropy, * size_t min_len, size_t max_len); * * This is a request to allocate and fill a buffer of size * |min_len| <= size <= |max_len| (in bytes) which contains * at least |entropy| bits of randomness. The buffer's address is * to be returned in |*pout| and the number of collected * randomness bytes (which may be less than the allocated size * of the buffer) as return value. * * If the callback fails to acquire at least |entropy| bits of * randomness, it shall return a buffer length of 0. * * CLEANUP_ENTROPY * * void cleanup_entropy(RAND_DRBG *ctx, * unsigned char *out, size_t outlen); * * A request to clear and free the buffer allocated by get_entropy(). * The values |out| and |outlen| are expected to be the random buffer's * address and length, as returned by the get_entropy() callback. * * GET_NONCE, CLEANUP_NONCE * * Signature and semantics of the get_nonce() and cleanup_nonce() * callbacks are analogous to get_entropy() and cleanup_entropy(). * Currently, the nonce is used only for the known answer tests. */ int RAND_DRBG_set_callbacks(RAND_DRBG *drbg, RAND_DRBG_get_entropy_fn get_entropy, RAND_DRBG_cleanup_entropy_fn cleanup_entropy, RAND_DRBG_get_nonce_fn get_nonce, RAND_DRBG_cleanup_nonce_fn cleanup_nonce) { if (drbg->state != DRBG_UNINITIALISED) return 0; drbg->get_entropy = get_entropy; drbg->cleanup_entropy = cleanup_entropy; drbg->get_nonce = get_nonce; drbg->cleanup_nonce = cleanup_nonce; return 1; } /* * Set the reseed interval. */ int RAND_DRBG_set_reseed_interval(RAND_DRBG *drbg, int interval) { if (interval < 0 || interval > MAX_RESEED) return 0; drbg->reseed_interval = interval; return 1; } /* * Get and set the EXDATA */ int RAND_DRBG_set_ex_data(RAND_DRBG *drbg, int idx, void *arg) { return CRYPTO_set_ex_data(&drbg->ex_data, idx, arg); } void *RAND_DRBG_get_ex_data(const RAND_DRBG *drbg, int idx) { return CRYPTO_get_ex_data(&drbg->ex_data, idx); } /* * The following functions provide a RAND_METHOD that works on the * global DRBG. They lock. */ /* * Initializes the DRBG with default settings. * For global DRBGs a global lock is created with the given name * Returns 1 on success, 0 on failure */ static int drbg_setup(RAND_DRBG *drbg, const char *name) { int ret = 1; if (name != NULL) { if (drbg->lock != NULL) { RANDerr(RAND_F_DRBG_SETUP, ERR_R_INTERNAL_ERROR); return 0; } drbg->lock = CRYPTO_THREAD_glock_new(name); if (drbg->lock == NULL) { RANDerr(RAND_F_DRBG_SETUP, RAND_R_FAILED_TO_CREATE_LOCK); return 0; } } ret &= RAND_DRBG_set(drbg, RAND_DRBG_NID, RAND_DRBG_FLAG_CTR_USE_DF) == 1; ret &= RAND_DRBG_set_callbacks(drbg, rand_drbg_get_entropy, rand_drbg_cleanup_entropy, NULL, NULL) == 1; /* * Ignore instantiation error so support just-in-time instantiation. * * The state of the drbg will be checked in RAND_DRBG_generate() and * an automatic recovery is attempted. */ RAND_DRBG_instantiate(drbg, (const unsigned char *) ossl_pers_string, sizeof(ossl_pers_string) - 1); return ret; } /* * Initialize the global DRBGs on first use. * Returns 1 on success, 0 on failure. */ DEFINE_RUN_ONCE_STATIC(do_rand_drbg_init) { int ret = 1; ret &= drbg_setup(&rand_drbg, "rand_drbg"); ret &= drbg_setup(&priv_drbg, "priv_drbg"); return ret; } /* Cleans up the given global DRBG */ static void drbg_cleanup(RAND_DRBG *drbg) { CRYPTO_THREAD_lock_free(drbg->lock); RAND_DRBG_uninstantiate(drbg); } /* Clean up the global DRBGs before exit */ void rand_drbg_cleanup_int(void) { drbg_cleanup(&rand_drbg); drbg_cleanup(&priv_drbg); } /* Implements the default OpenSSL RAND_bytes() method */ static int drbg_bytes(unsigned char *out, int count) { int ret = 0; size_t chunk; RAND_DRBG *drbg = RAND_DRBG_get0_global(); if (drbg == NULL) return 0; CRYPTO_THREAD_write_lock(drbg->lock); if (drbg->state == DRBG_UNINITIALISED) goto err; for ( ; count > 0; count -= chunk, out += chunk) { chunk = count; if (chunk > drbg->max_request) chunk = drbg->max_request; ret = RAND_DRBG_generate(drbg, out, chunk, 0, NULL, 0); if (!ret) goto err; } ret = 1; err: CRYPTO_THREAD_unlock(drbg->lock); return ret; } /* Implements the default OpenSSL RAND_add() method */ static int drbg_add(const void *buf, int num, double randomness) { int ret = 0; RAND_DRBG *drbg = RAND_DRBG_get0_global(); if (drbg == NULL) return 0; if (num < 0 || randomness < 0.0) return 0; if (randomness > (double)drbg->max_entropylen) { /* * The purpose of this check is to bound |randomness| by a * relatively small value in order to prevent an integer * overflow when multiplying by 8 in the rand_drbg_restart() * call below. */ return 0; } CRYPTO_THREAD_write_lock(drbg->lock); ret = rand_drbg_restart(drbg, buf, (size_t)(unsigned int)num, (size_t)(8*randomness)); CRYPTO_THREAD_unlock(drbg->lock); return ret; } /* Implements the default OpenSSL RAND_seed() method */ static int drbg_seed(const void *buf, int num) { return drbg_add(buf, num, num); } /* Implements the default OpenSSL RAND_status() method */ static int drbg_status(void) { int ret; RAND_DRBG *drbg = RAND_DRBG_get0_global(); if (drbg == NULL) return 0; CRYPTO_THREAD_write_lock(drbg->lock); ret = drbg->state == DRBG_READY ? 1 : 0; CRYPTO_THREAD_unlock(drbg->lock); return ret; } /* * Get the global public DRBG. * Returns pointer to the DRBG on success, NULL on failure. */ RAND_DRBG *RAND_DRBG_get0_global(void) { if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init)) return NULL; return &rand_drbg; } /* * Get the global private DRBG. * Returns pointer to the DRBG on success, NULL on failure. */ RAND_DRBG *RAND_DRBG_get0_priv_global(void) { if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init)) return NULL; return &priv_drbg; } RAND_METHOD rand_meth = { drbg_seed, drbg_bytes, NULL, drbg_add, drbg_bytes, drbg_status }; RAND_METHOD *RAND_OpenSSL(void) { return &rand_meth; }