| /* |
| * Copyright 1995-2021 The OpenSSL Project Authors. All Rights Reserved. |
| * |
| * Licensed under the Apache License 2.0 (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 <stdio.h> |
| #include <time.h> |
| #include "internal/cryptlib.h" |
| #include <openssl/opensslconf.h> |
| #include "crypto/rand.h" |
| #include <openssl/engine.h> |
| #include "internal/thread_once.h" |
| #include "crypto/rand_pool.h" |
| |
| /* |
| * Allocate memory and initialize a new random pool |
| */ |
| RAND_POOL *ossl_rand_pool_new(int entropy_requested, int secure, |
| size_t min_len, size_t max_len) |
| { |
| RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool)); |
| size_t min_alloc_size = RAND_POOL_MIN_ALLOCATION(secure); |
| |
| if (pool == NULL) { |
| ERR_raise(ERR_LIB_RAND, 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->alloc_len = min_len < min_alloc_size ? min_alloc_size : min_len; |
| if (pool->alloc_len > pool->max_len) |
| pool->alloc_len = pool->max_len; |
| |
| if (secure) |
| pool->buffer = OPENSSL_secure_zalloc(pool->alloc_len); |
| else |
| pool->buffer = OPENSSL_zalloc(pool->alloc_len); |
| |
| if (pool->buffer == NULL) { |
| ERR_raise(ERR_LIB_RAND, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| |
| pool->entropy_requested = entropy_requested; |
| pool->secure = secure; |
| 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 <master> DRBG. |
| */ |
| RAND_POOL *ossl_rand_pool_attach(const unsigned char *buffer, size_t len, |
| size_t entropy) |
| { |
| RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool)); |
| |
| if (pool == NULL) { |
| ERR_raise(ERR_LIB_RAND, 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->alloc_len = pool->len; |
| pool->entropy = entropy; |
| |
| return pool; |
| } |
| |
| /* |
| * Free |pool|, securely erasing its buffer. |
| */ |
| void ossl_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 ossl_rand_pool_attach() as `const unsigned char*`. |
| * (see corresponding comment in ossl_rand_pool_attach()). |
| */ |
| if (!pool->attached) { |
| if (pool->secure) |
| OPENSSL_secure_clear_free(pool->buffer, pool->alloc_len); |
| else |
| OPENSSL_clear_free(pool->buffer, pool->alloc_len); |
| } |
| |
| OPENSSL_free(pool); |
| } |
| |
| /* |
| * Return the |pool|'s buffer to the caller (readonly). |
| */ |
| const unsigned char *ossl_rand_pool_buffer(RAND_POOL *pool) |
| { |
| return pool->buffer; |
| } |
| |
| /* |
| * Return the |pool|'s entropy to the caller. |
| */ |
| size_t ossl_rand_pool_entropy(RAND_POOL *pool) |
| { |
| return pool->entropy; |
| } |
| |
| /* |
| * Return the |pool|'s buffer length to the caller. |
| */ |
| size_t ossl_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() or to re-attach it |
| * again to the pool using ossl_rand_pool_reattach(). |
| */ |
| unsigned char *ossl_rand_pool_detach(RAND_POOL *pool) |
| { |
| unsigned char *ret = pool->buffer; |
| pool->buffer = NULL; |
| pool->entropy = 0; |
| return ret; |
| } |
| |
| /* |
| * Re-attach the |pool| buffer. It is only allowed to pass |
| * the |buffer| which was previously detached from the same pool. |
| */ |
| void ossl_rand_pool_reattach(RAND_POOL *pool, unsigned char *buffer) |
| { |
| pool->buffer = buffer; |
| OPENSSL_cleanse(pool->buffer, pool->len); |
| pool->len = 0; |
| } |
| |
| /* |
| * 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 ossl_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 ossl_rand_pool_entropy_needed(RAND_POOL *pool) |
| { |
| if (pool->entropy < pool->entropy_requested) |
| return pool->entropy_requested - pool->entropy; |
| |
| return 0; |
| } |
| |
| /* Increase the allocation size -- not usable for an attached pool */ |
| static int rand_pool_grow(RAND_POOL *pool, size_t len) |
| { |
| if (len > pool->alloc_len - pool->len) { |
| unsigned char *p; |
| const size_t limit = pool->max_len / 2; |
| size_t newlen = pool->alloc_len; |
| |
| if (pool->attached || len > pool->max_len - pool->len) { |
| ERR_raise(ERR_LIB_RAND, ERR_R_INTERNAL_ERROR); |
| return 0; |
| } |
| |
| do |
| newlen = newlen < limit ? newlen * 2 : pool->max_len; |
| while (len > newlen - pool->len); |
| |
| if (pool->secure) |
| p = OPENSSL_secure_zalloc(newlen); |
| else |
| p = OPENSSL_zalloc(newlen); |
| if (p == NULL) { |
| ERR_raise(ERR_LIB_RAND, ERR_R_MALLOC_FAILURE); |
| return 0; |
| } |
| memcpy(p, pool->buffer, pool->len); |
| if (pool->secure) |
| OPENSSL_secure_clear_free(pool->buffer, pool->alloc_len); |
| else |
| OPENSSL_clear_free(pool->buffer, pool->alloc_len); |
| pool->buffer = p; |
| pool->alloc_len = newlen; |
| } |
| return 1; |
| } |
| |
| /* |
| * 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 ossl_rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_factor) |
| { |
| size_t bytes_needed; |
| size_t entropy_needed = ossl_rand_pool_entropy_needed(pool); |
| |
| if (entropy_factor < 1) { |
| ERR_raise(ERR_LIB_RAND, 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 */ |
| ERR_raise(ERR_LIB_RAND, 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; |
| |
| /* |
| * Make sure the buffer is large enough for the requested amount |
| * of data. This guarantees that existing code patterns where |
| * ossl_rand_pool_add_begin, ossl_rand_pool_add_end or ossl_rand_pool_add |
| * are used to collect entropy data without any error handling |
| * whatsoever, continue to be valid. |
| * Furthermore if the allocation here fails once, make sure that |
| * we don't fall back to a less secure or even blocking random source, |
| * as that could happen by the existing code patterns. |
| * This is not a concern for additional data, therefore that |
| * is not needed if rand_pool_grow fails in other places. |
| */ |
| if (!rand_pool_grow(pool, bytes_needed)) { |
| /* persistent error for this pool */ |
| pool->max_len = pool->len = 0; |
| return 0; |
| } |
| |
| return bytes_needed; |
| } |
| |
| /* Returns the remaining number of bytes available */ |
| size_t ossl_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 ossl_rand_pool_add(RAND_POOL *pool, |
| const unsigned char *buffer, size_t len, size_t entropy) |
| { |
| if (len > pool->max_len - pool->len) { |
| ERR_raise(ERR_LIB_RAND, RAND_R_ENTROPY_INPUT_TOO_LONG); |
| return 0; |
| } |
| |
| if (pool->buffer == NULL) { |
| ERR_raise(ERR_LIB_RAND, ERR_R_INTERNAL_ERROR); |
| return 0; |
| } |
| |
| if (len > 0) { |
| /* |
| * This is to protect us from accidentally passing the buffer |
| * returned from ossl_rand_pool_add_begin. |
| * The check for alloc_len makes sure we do not compare the |
| * address of the end of the allocated memory to something |
| * different, since that comparison would have an |
| * indeterminate result. |
| */ |
| if (pool->alloc_len > pool->len && pool->buffer + pool->len == buffer) { |
| ERR_raise(ERR_LIB_RAND, ERR_R_INTERNAL_ERROR); |
| return 0; |
| } |
| /* |
| * We have that only for cases when a pool is used to collect |
| * additional data. |
| * For entropy data, as long as the allocation request stays within |
| * the limits given by ossl_rand_pool_bytes_needed this rand_pool_grow |
| * below is guaranteed to succeed, thus no allocation happens. |
| */ |
| if (!rand_pool_grow(pool, len)) |
| return 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, ossl_rand_pool_add_end() needs to be called |
| * to finish the update operation (see next comment). |
| */ |
| unsigned char *ossl_rand_pool_add_begin(RAND_POOL *pool, size_t len) |
| { |
| if (len == 0) |
| return NULL; |
| |
| if (len > pool->max_len - pool->len) { |
| ERR_raise(ERR_LIB_RAND, RAND_R_RANDOM_POOL_OVERFLOW); |
| return NULL; |
| } |
| |
| if (pool->buffer == NULL) { |
| ERR_raise(ERR_LIB_RAND, ERR_R_INTERNAL_ERROR); |
| return NULL; |
| } |
| |
| /* |
| * As long as the allocation request stays within the limits given |
| * by ossl_rand_pool_bytes_needed this rand_pool_grow below is guaranteed |
| * to succeed, thus no allocation happens. |
| * We have that only for cases when a pool is used to collect |
| * additional data. Then the buffer might need to grow here, |
| * and of course the caller is responsible to check the return |
| * value of this function. |
| */ |
| if (!rand_pool_grow(pool, len)) |
| 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 |
| * ossl_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 ossl_rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy) |
| { |
| if (len > pool->alloc_len - pool->len) { |
| ERR_raise(ERR_LIB_RAND, RAND_R_RANDOM_POOL_OVERFLOW); |
| return 0; |
| } |
| |
| if (len > 0) { |
| pool->len += len; |
| pool->entropy += entropy; |
| } |
| |
| return 1; |
| } |