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7998e7dc07
The 'rand_generate' method is not well suited for being used with weak entropy sources in the 'get_entropy' callback, because the caller needs to provide a preallocated buffer without knowing how much bytes are actually needed to collect the required entropy. Instead we use the 'rand_get_seed' and 'rand_clear_seed' methods which were exactly designed for this purpose: it's the callee who allocates and fills the buffer, and finally cleans it up again. The 'rand_get_seed' and 'rand_clear_seed' methods are currently optional for a provided random generator. We could fall back to using 'rand_generate' if those methods are not implemented. However, imo it would be better to simply make them an officially documented requirement for seed sources. Fixes #22332 Reviewed-by: Tomas Mraz <tomas@openssl.org> Reviewed-by: Paul Dale <pauli@openssl.org> Reviewed-by: Richard Levitte <levitte@openssl.org> Reviewed-by: Matt Caswell <matt@openssl.org> (Merged from https://github.com/openssl/openssl/pull/22394)
133 lines
3.9 KiB
C
133 lines
3.9 KiB
C
/*
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* Copyright 2020-2023 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the Apache License 2.0 (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include "rand_local.h"
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#include "crypto/evp.h"
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#include "crypto/rand.h"
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#include "crypto/rand_pool.h"
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#include "internal/core.h"
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#include <openssl/core_dispatch.h>
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#include <openssl/err.h>
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size_t ossl_rand_get_entropy(ossl_unused OSSL_LIB_CTX *ctx,
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unsigned char **pout, int entropy,
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size_t min_len, size_t max_len)
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{
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size_t ret = 0;
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size_t entropy_available;
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RAND_POOL *pool;
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pool = ossl_rand_pool_new(entropy, 1, min_len, max_len);
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if (pool == NULL) {
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ERR_raise(ERR_LIB_RAND, ERR_R_RAND_LIB);
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return 0;
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}
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/* Get entropy by polling system entropy sources. */
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entropy_available = ossl_pool_acquire_entropy(pool);
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if (entropy_available > 0) {
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ret = ossl_rand_pool_length(pool);
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*pout = ossl_rand_pool_detach(pool);
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}
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ossl_rand_pool_free(pool);
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return ret;
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}
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size_t ossl_rand_get_user_entropy(OSSL_LIB_CTX *ctx,
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unsigned char **pout, int entropy,
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size_t min_len, size_t max_len)
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{
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EVP_RAND_CTX *rng = ossl_rand_get0_seed_noncreating(ctx);
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if (rng != NULL && evp_rand_can_seed(rng))
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return evp_rand_get_seed(rng, pout, entropy, min_len, max_len,
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0, NULL, 0);
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else
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return ossl_rand_get_entropy(ctx, pout, entropy, min_len, max_len);
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}
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void ossl_rand_cleanup_entropy(ossl_unused OSSL_LIB_CTX *ctx,
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unsigned char *buf, size_t len)
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{
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OPENSSL_secure_clear_free(buf, len);
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}
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void ossl_rand_cleanup_user_entropy(OSSL_LIB_CTX *ctx,
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unsigned char *buf, size_t len)
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{
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EVP_RAND_CTX *rng = ossl_rand_get0_seed_noncreating(ctx);
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if (rng != NULL && evp_rand_can_seed(rng))
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evp_rand_clear_seed(rng, buf, len);
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else
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OPENSSL_secure_clear_free(buf, len);
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}
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size_t ossl_rand_get_nonce(ossl_unused OSSL_LIB_CTX *ctx,
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unsigned char **pout,
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size_t min_len, ossl_unused size_t max_len,
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const void *salt, size_t salt_len)
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{
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size_t ret = 0;
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RAND_POOL *pool;
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pool = ossl_rand_pool_new(0, 0, min_len, max_len);
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if (pool == NULL) {
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ERR_raise(ERR_LIB_RAND, ERR_R_RAND_LIB);
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return 0;
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}
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if (!ossl_pool_add_nonce_data(pool))
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goto err;
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if (salt != NULL && !ossl_rand_pool_add(pool, salt, salt_len, 0))
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goto err;
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ret = ossl_rand_pool_length(pool);
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*pout = ossl_rand_pool_detach(pool);
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err:
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ossl_rand_pool_free(pool);
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return ret;
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}
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size_t ossl_rand_get_user_nonce(OSSL_LIB_CTX *ctx,
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unsigned char **pout,
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size_t min_len, size_t max_len,
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const void *salt, size_t salt_len)
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{
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unsigned char *buf;
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EVP_RAND_CTX *rng = ossl_rand_get0_seed_noncreating(ctx);
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if (rng == NULL)
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return ossl_rand_get_nonce(ctx, pout, min_len, max_len, salt, salt_len);
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if ((buf = OPENSSL_malloc(min_len)) == NULL)
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return 0;
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if (!EVP_RAND_generate(rng, buf, min_len, 0, 0, salt, salt_len)) {
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OPENSSL_free(buf);
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return 0;
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}
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*pout = buf;
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return min_len;
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}
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void ossl_rand_cleanup_nonce(ossl_unused OSSL_LIB_CTX *ctx,
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unsigned char *buf, size_t len)
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{
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OPENSSL_clear_free(buf, len);
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}
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void ossl_rand_cleanup_user_nonce(ossl_unused OSSL_LIB_CTX *ctx,
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unsigned char *buf, size_t len)
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{
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OPENSSL_clear_free(buf, len);
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}
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