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c16de9d832
Reseeding is handled very differently by the classic RAND_METHOD API and the new RAND_DRBG api. These differences led to some problems when the new RAND_DRBG was made the default OpenSSL RNG. In particular, RAND_add() did not work as expected anymore. These issues are discussed on the thread '[openssl-dev] Plea for a new public OpenSSL RNG API' and in Pull Request #4328. This commit fixes the mentioned issues, introducing the following changes: - Replace the fixed size RAND_BYTES_BUFFER by a new RAND_POOL API which facilitates collecting entropy by the get_entropy() callback. - Don't use RAND_poll()/RAND_add() for collecting entropy from the get_entropy() callback anymore. Instead, replace RAND_poll() by RAND_POOL_acquire_entropy(). - Add a new function rand_drbg_restart() which tries to get the DRBG in an instantiated state by all means, regardless of the current state (uninstantiated, error, ...) the DRBG is in. If the caller provides entropy or additional input, it will be used for reseeding. - Restore the original documented behaviour of RAND_add() and RAND_poll() (namely to reseed the DRBG immediately) by a new implementation based on rand_drbg_restart(). - Add automatic error recovery from temporary failures of the entropy source to RAND_DRBG_generate() using the rand_drbg_restart() function. Reviewed-by: Paul Dale <paul.dale@oracle.com> Reviewed-by: Kurt Roeckx <kurt@roeckx.be> Reviewed-by: Rich Salz <rsalz@openssl.org> Reviewed-by: Ben Kaduk <kaduk@mit.edu> (Merged from https://github.com/openssl/openssl/pull/4328)
131 lines
3.8 KiB
C
131 lines
3.8 KiB
C
/*
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* Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (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 "internal/cryptlib.h"
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#include <openssl/rand.h>
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#include "rand_lcl.h"
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#if defined(OPENSSL_SYS_WINDOWS) || defined(OPENSSL_SYS_WIN32)
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# ifndef OPENSSL_RAND_SEED_OS
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# error "Unsupported seeding method configured; must be os"
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# endif
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# include <windows.h>
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/* On Windows 7 or higher use BCrypt instead of the legacy CryptoAPI */
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# if defined(_MSC_VER) && defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x0601
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# define USE_BCRYPTGENRANDOM
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# endif
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# ifdef USE_BCRYPTGENRANDOM
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# include <bcrypt.h>
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# pragma comment(lib, "bcrypt.lib")
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# ifndef STATUS_SUCCESS
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# define STATUS_SUCCESS ((NTSTATUS)0x00000000L)
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# endif
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# else
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# include <wincrypt.h>
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/*
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* Intel hardware RNG CSP -- available from
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* http://developer.intel.com/design/security/rng/redist_license.htm
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*/
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# define PROV_INTEL_SEC 22
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# define INTEL_DEF_PROV L"Intel Hardware Cryptographic Service Provider"
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# endif
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size_t RAND_POOL_acquire_entropy(RAND_POOL *pool)
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{
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# ifndef USE_BCRYPTGENRANDOM
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HCRYPTPROV hProvider;
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# endif
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unsigned char *buffer;
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size_t bytes_needed;
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size_t entropy_available = 0;
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# ifdef OPENSSL_RAND_SEED_RDTSC
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entropy_available = rand_acquire_entropy_from_tsc(pool);
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if (entropy_available > 0)
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return entropy_available;
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# endif
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# ifdef OPENSSL_RAND_SEED_RDCPU
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entropy_available = rand_acquire_entropy_from_cpu(pool);
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if (entropy_available > 0)
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return entropy_available;
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# endif
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# ifdef USE_BCRYPTGENRANDOM
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bytes_needed = RAND_POOL_bytes_needed(pool, 8 /*entropy_per_byte*/);
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buffer = RAND_POOL_add_begin(pool, bytes_needed);
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if (buffer != NULL) {
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size_t bytes = 0;
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if (BCryptGenRandom(NULL, buffer, bytes_needed,
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BCRYPT_USE_SYSTEM_PREFERRED_RNG) == STATUS_SUCCESS)
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bytes = bytes_needed;
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entropy_available = RAND_POOL_add_end(pool, bytes, 8 * bytes);
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}
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if (entropy_available > 0)
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return entropy_available;
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# else
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bytes_needed = RAND_POOL_bytes_needed(pool, 8 /*entropy_per_byte*/);
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buffer = RAND_POOL_add_begin(pool, bytes_needed);
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if (buffer != NULL) {
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size_t bytes = 0;
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/* poll the CryptoAPI PRNG */
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if (CryptAcquireContextW(&hProvider, NULL, NULL, PROV_RSA_FULL,
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CRYPT_VERIFYCONTEXT | CRYPT_SILENT) != 0) {
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if (CryptGenRandom(hProvider, bytes_needed, buffer) != 0)
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bytes = bytes_needed;
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CryptReleaseContext(hProvider, 0);
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}
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entropy_available = RAND_POOL_add_end(pool, bytes, 8 * bytes);
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}
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if (entropy_available > 0)
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return entropy_available;
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bytes_needed = RAND_POOL_bytes_needed(pool, 8 /*entropy_per_byte*/);
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buffer = RAND_POOL_add_begin(pool, bytes_needed);
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if (buffer != NULL) {
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size_t bytes = 0;
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/* poll the Pentium PRG with CryptoAPI */
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if (CryptAcquireContextW(&hProvider, NULL,
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INTEL_DEF_PROV, PROV_INTEL_SEC,
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CRYPT_VERIFYCONTEXT | CRYPT_SILENT) != 0) {
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if (CryptGenRandom(hProvider, bytes_needed, buffer) != 0)
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bytes = bytes_needed;
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CryptReleaseContext(hProvider, 0);
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}
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entropy_available = RAND_POOL_add_end(pool, bytes, 8 * bytes);
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}
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if (entropy_available > 0)
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return entropy_available;
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# endif
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return RAND_POOL_entropy_available(pool);
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}
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# if OPENSSL_API_COMPAT < 0x10100000L
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int RAND_event(UINT iMsg, WPARAM wParam, LPARAM lParam)
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{
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RAND_poll();
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return RAND_status();
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}
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void RAND_screen(void)
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{
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RAND_poll();
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}
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# endif
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#endif
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