/* * Copyright 1995-2016 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 "e_os.h" #if !(defined(OPENSSL_SYS_WIN32) || defined(OPENSSL_SYS_VXWORKS) || defined(OPENSSL_SYS_DSPBIOS)) # include #endif #if defined(OPENSSL_SYS_VXWORKS) # include #endif #include #include #include #include #include "rand_lcl.h" #include #include #ifdef OPENSSL_FIPS # include #endif #ifdef BN_DEBUG # define PREDICT #endif /* #define PREDICT 1 */ #define STATE_SIZE 1023 static size_t state_num = 0, state_index = 0; static unsigned char state[STATE_SIZE + MD_DIGEST_LENGTH]; static unsigned char md[MD_DIGEST_LENGTH]; static long md_count[2] = { 0, 0 }; static double entropy = 0; static int initialized = 0; static CRYPTO_RWLOCK *rand_lock = NULL; static CRYPTO_RWLOCK *rand_tmp_lock = NULL; static CRYPTO_ONCE rand_lock_init = CRYPTO_ONCE_STATIC_INIT; /* May be set only when a thread holds rand_lock (to prevent double locking) */ static unsigned int crypto_lock_rand = 0; /* access to locking_threadid is synchronized by rand_tmp_lock */ /* valid iff crypto_lock_rand is set */ static CRYPTO_THREAD_ID locking_threadid; #ifdef PREDICT int rand_predictable = 0; #endif static int rand_hw_seed(EVP_MD_CTX *ctx); static void rand_cleanup(void); static int rand_seed(const void *buf, int num); static int rand_add(const void *buf, int num, double add_entropy); static int rand_bytes(unsigned char *buf, int num, int pseudo); static int rand_nopseudo_bytes(unsigned char *buf, int num); #if OPENSSL_API_COMPAT < 0x10100000L static int rand_pseudo_bytes(unsigned char *buf, int num); #endif static int rand_status(void); static RAND_METHOD rand_meth = { rand_seed, rand_nopseudo_bytes, rand_cleanup, rand_add, #if OPENSSL_API_COMPAT < 0x10100000L rand_pseudo_bytes, #else NULL, #endif rand_status }; DEFINE_RUN_ONCE_STATIC(do_rand_lock_init) { OPENSSL_init_crypto(0, NULL); rand_lock = CRYPTO_THREAD_lock_new(); rand_tmp_lock = CRYPTO_THREAD_lock_new(); return rand_lock != NULL && rand_tmp_lock != NULL; } RAND_METHOD *RAND_OpenSSL(void) { return (&rand_meth); } static void rand_cleanup(void) { OPENSSL_cleanse(state, sizeof(state)); state_num = 0; state_index = 0; OPENSSL_cleanse(md, MD_DIGEST_LENGTH); md_count[0] = 0; md_count[1] = 0; entropy = 0; initialized = 0; CRYPTO_THREAD_lock_free(rand_lock); CRYPTO_THREAD_lock_free(rand_tmp_lock); } static int rand_add(const void *buf, int num, double add) { int i, j, k, st_idx; long md_c[2]; unsigned char local_md[MD_DIGEST_LENGTH]; EVP_MD_CTX *m; int do_not_lock; int rv = 0; if (!num) return 1; /* * (Based on the rand(3) manpage) * * The input is chopped up into units of 20 bytes (or less for * the last block). Each of these blocks is run through the hash * function as follows: The data passed to the hash function * is the current 'md', the same number of bytes from the 'state' * (the location determined by in incremented looping index) as * the current 'block', the new key data 'block', and 'count' * (which is incremented after each use). * The result of this is kept in 'md' and also xored into the * 'state' at the same locations that were used as input into the * hash function. */ m = EVP_MD_CTX_new(); if (m == NULL) goto err; if (!RUN_ONCE(&rand_lock_init, do_rand_lock_init)) goto err; /* check if we already have the lock */ if (crypto_lock_rand) { CRYPTO_THREAD_ID cur = CRYPTO_THREAD_get_current_id(); CRYPTO_THREAD_read_lock(rand_tmp_lock); do_not_lock = CRYPTO_THREAD_compare_id(locking_threadid, cur); CRYPTO_THREAD_unlock(rand_tmp_lock); } else do_not_lock = 0; if (!do_not_lock) CRYPTO_THREAD_write_lock(rand_lock); st_idx = state_index; /* * use our own copies of the counters so that even if a concurrent thread * seeds with exactly the same data and uses the same subarray there's * _some_ difference */ md_c[0] = md_count[0]; md_c[1] = md_count[1]; memcpy(local_md, md, sizeof(md)); /* state_index <= state_num <= STATE_SIZE */ state_index += num; if (state_index >= STATE_SIZE) { state_index %= STATE_SIZE; state_num = STATE_SIZE; } else if (state_num < STATE_SIZE) { if (state_index > state_num) state_num = state_index; } /* state_index <= state_num <= STATE_SIZE */ /* * state[st_idx], ..., state[(st_idx + num - 1) % STATE_SIZE] are what we * will use now, but other threads may use them as well */ md_count[1] += (num / MD_DIGEST_LENGTH) + (num % MD_DIGEST_LENGTH > 0); if (!do_not_lock) CRYPTO_THREAD_unlock(rand_lock); for (i = 0; i < num; i += MD_DIGEST_LENGTH) { j = (num - i); j = (j > MD_DIGEST_LENGTH) ? MD_DIGEST_LENGTH : j; if (!MD_Init(m)) goto err; if (!MD_Update(m, local_md, MD_DIGEST_LENGTH)) goto err; k = (st_idx + j) - STATE_SIZE; if (k > 0) { if (!MD_Update(m, &(state[st_idx]), j - k)) goto err; if (!MD_Update(m, &(state[0]), k)) goto err; } else if (!MD_Update(m, &(state[st_idx]), j)) goto err; /* DO NOT REMOVE THE FOLLOWING CALL TO MD_Update()! */ if (!MD_Update(m, buf, j)) goto err; /* * We know that line may cause programs such as purify and valgrind * to complain about use of uninitialized data. The problem is not, * it's with the caller. Removing that line will make sure you get * really bad randomness and thereby other problems such as very * insecure keys. */ if (!MD_Update(m, (unsigned char *)&(md_c[0]), sizeof(md_c))) goto err; if (!MD_Final(m, local_md)) goto err; md_c[1]++; buf = (const char *)buf + j; for (k = 0; k < j; k++) { /* * Parallel threads may interfere with this, but always each byte * of the new state is the XOR of some previous value of its and * local_md (intermediate values may be lost). Alway using locking * could hurt performance more than necessary given that * conflicts occur only when the total seeding is longer than the * random state. */ state[st_idx++] ^= local_md[k]; if (st_idx >= STATE_SIZE) st_idx = 0; } } if (!do_not_lock) CRYPTO_THREAD_write_lock(rand_lock); /* * Don't just copy back local_md into md -- this could mean that other * thread's seeding remains without effect (except for the incremented * counter). By XORing it we keep at least as much entropy as fits into * md. */ for (k = 0; k < (int)sizeof(md); k++) { md[k] ^= local_md[k]; } if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */ entropy += add; if (!do_not_lock) CRYPTO_THREAD_unlock(rand_lock); rv = 1; err: EVP_MD_CTX_free(m); return rv; } static int rand_seed(const void *buf, int num) { return rand_add(buf, num, (double)num); } static int rand_bytes(unsigned char *buf, int num, int pseudo) { static volatile int stirred_pool = 0; int i, j, k; size_t num_ceil, st_idx, st_num; int ok; long md_c[2]; unsigned char local_md[MD_DIGEST_LENGTH]; EVP_MD_CTX *m; #ifndef GETPID_IS_MEANINGLESS pid_t curr_pid = getpid(); #endif time_t curr_time = time(NULL); int do_stir_pool = 0; /* time value for various platforms */ #ifdef OPENSSL_SYS_WIN32 FILETIME tv; # ifdef _WIN32_WCE SYSTEMTIME t; GetSystemTime(&t); SystemTimeToFileTime(&t, &tv); # else GetSystemTimeAsFileTime(&tv); # endif #elif defined(OPENSSL_SYS_VXWORKS) struct timespec tv; clock_gettime(CLOCK_REALTIME, &ts); #elif defined(OPENSSL_SYS_DSPBIOS) unsigned long long tv, OPENSSL_rdtsc(); tv = OPENSSL_rdtsc(); #else struct timeval tv; gettimeofday(&tv, NULL); #endif #ifdef PREDICT if (rand_predictable) { static unsigned char val = 0; for (i = 0; i < num; i++) buf[i] = val++; return (1); } #endif if (num <= 0) return 1; m = EVP_MD_CTX_new(); if (m == NULL) goto err_mem; /* round upwards to multiple of MD_DIGEST_LENGTH/2 */ num_ceil = (1 + (num - 1) / (MD_DIGEST_LENGTH / 2)) * (MD_DIGEST_LENGTH / 2); /* * (Based on the rand(3) manpage:) * * For each group of 10 bytes (or less), we do the following: * * Input into the hash function the local 'md' (which is initialized from * the global 'md' before any bytes are generated), the bytes that are to * be overwritten by the random bytes, and bytes from the 'state' * (incrementing looping index). From this digest output (which is kept * in 'md'), the top (up to) 10 bytes are returned to the caller and the * bottom 10 bytes are xored into the 'state'. * * Finally, after we have finished 'num' random bytes for the * caller, 'count' (which is incremented) and the local and global 'md' * are fed into the hash function and the results are kept in the * global 'md'. */ if (!RUN_ONCE(&rand_lock_init, do_rand_lock_init)) goto err_mem; CRYPTO_THREAD_write_lock(rand_lock); /* * We could end up in an async engine while holding this lock so ensure * we don't pause and cause a deadlock */ ASYNC_block_pause(); /* prevent rand_bytes() from trying to obtain the lock again */ CRYPTO_THREAD_write_lock(rand_tmp_lock); locking_threadid = CRYPTO_THREAD_get_current_id(); CRYPTO_THREAD_unlock(rand_tmp_lock); crypto_lock_rand = 1; if (!initialized) { RAND_poll(); initialized = 1; } if (!stirred_pool) do_stir_pool = 1; ok = (entropy >= ENTROPY_NEEDED); if (!ok) { /* * If the PRNG state is not yet unpredictable, then seeing the PRNG * output may help attackers to determine the new state; thus we have * to decrease the entropy estimate. Once we've had enough initial * seeding we don't bother to adjust the entropy count, though, * because we're not ambitious to provide *information-theoretic* * randomness. NOTE: This approach fails if the program forks before * we have enough entropy. Entropy should be collected in a separate * input pool and be transferred to the output pool only when the * entropy limit has been reached. */ entropy -= num; if (entropy < 0) entropy = 0; } if (do_stir_pool) { /* * In the output function only half of 'md' remains secret, so we * better make sure that the required entropy gets 'evenly * distributed' through 'state', our randomness pool. The input * function (rand_add) chains all of 'md', which makes it more * suitable for this purpose. */ int n = STATE_SIZE; /* so that the complete pool gets accessed */ while (n > 0) { #if MD_DIGEST_LENGTH > 20 # error "Please adjust DUMMY_SEED." #endif #define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */ /* * Note that the seed does not matter, it's just that * rand_add expects to have something to hash. */ rand_add(DUMMY_SEED, MD_DIGEST_LENGTH, 0.0); n -= MD_DIGEST_LENGTH; } if (ok) stirred_pool = 1; } st_idx = state_index; st_num = state_num; md_c[0] = md_count[0]; md_c[1] = md_count[1]; memcpy(local_md, md, sizeof(md)); state_index += num_ceil; if (state_index > state_num) state_index %= state_num; /* * state[st_idx], ..., state[(st_idx + num_ceil - 1) % st_num] are now * ours (but other threads may use them too) */ md_count[0] += 1; /* before unlocking, we must clear 'crypto_lock_rand' */ crypto_lock_rand = 0; ASYNC_unblock_pause(); CRYPTO_THREAD_unlock(rand_lock); while (num > 0) { /* num_ceil -= MD_DIGEST_LENGTH/2 */ j = (num >= MD_DIGEST_LENGTH / 2) ? MD_DIGEST_LENGTH / 2 : num; num -= j; if (!MD_Init(m)) goto err; #ifndef GETPID_IS_MEANINGLESS if (curr_pid) { /* just in the first iteration to save time */ if (!MD_Update(m, (unsigned char *)&curr_pid, sizeof(curr_pid))) goto err; curr_pid = 0; } #endif if (curr_time) { /* just in the first iteration to save time */ if (!MD_Update(m, (unsigned char *)&curr_time, sizeof(curr_time))) goto err; if (!MD_Update(m, (unsigned char *)&tv, sizeof(tv))) goto err; curr_time = 0; if (!rand_hw_seed(m)) goto err; } if (!MD_Update(m, local_md, MD_DIGEST_LENGTH)) goto err; if (!MD_Update(m, (unsigned char *)&(md_c[0]), sizeof(md_c))) goto err; k = (st_idx + MD_DIGEST_LENGTH / 2) - st_num; if (k > 0) { if (!MD_Update(m, &(state[st_idx]), MD_DIGEST_LENGTH / 2 - k)) goto err; if (!MD_Update(m, &(state[0]), k)) goto err; } else if (!MD_Update(m, &(state[st_idx]), MD_DIGEST_LENGTH / 2)) goto err; if (!MD_Final(m, local_md)) goto err; for (i = 0; i < MD_DIGEST_LENGTH / 2; i++) { /* may compete with other threads */ state[st_idx++] ^= local_md[i]; if (st_idx >= st_num) st_idx = 0; if (i < j) *(buf++) = local_md[i + MD_DIGEST_LENGTH / 2]; } } if (!MD_Init(m) || !MD_Update(m, (unsigned char *)&(md_c[0]), sizeof(md_c)) || !MD_Update(m, local_md, MD_DIGEST_LENGTH)) goto err; CRYPTO_THREAD_write_lock(rand_lock); /* * Prevent deadlocks if we end up in an async engine */ ASYNC_block_pause(); if (!MD_Update(m, md, MD_DIGEST_LENGTH) || !MD_Final(m, md)) { ASYNC_unblock_pause(); CRYPTO_THREAD_unlock(rand_lock); goto err; } ASYNC_unblock_pause(); CRYPTO_THREAD_unlock(rand_lock); EVP_MD_CTX_free(m); if (ok) return (1); else if (pseudo) return 0; else { RANDerr(RAND_F_RAND_BYTES, RAND_R_PRNG_NOT_SEEDED); ERR_add_error_data(1, "You need to read the OpenSSL FAQ, " "https://www.openssl.org/docs/faq.html"); return (0); } err: RANDerr(RAND_F_RAND_BYTES, ERR_R_EVP_LIB); EVP_MD_CTX_free(m); return 0; err_mem: RANDerr(RAND_F_RAND_BYTES, ERR_R_MALLOC_FAILURE); EVP_MD_CTX_free(m); return 0; } static int rand_nopseudo_bytes(unsigned char *buf, int num) { return rand_bytes(buf, num, 0); } #if OPENSSL_API_COMPAT < 0x10100000L /* * pseudo-random bytes that are guaranteed to be unique but not unpredictable */ static int rand_pseudo_bytes(unsigned char *buf, int num) { return rand_bytes(buf, num, 1); } #endif static int rand_status(void) { CRYPTO_THREAD_ID cur; int ret; int do_not_lock; if (!RUN_ONCE(&rand_lock_init, do_rand_lock_init)) return 0; cur = CRYPTO_THREAD_get_current_id(); /* * check if we already have the lock (could happen if a RAND_poll() * implementation calls RAND_status()) */ if (crypto_lock_rand) { CRYPTO_THREAD_read_lock(rand_tmp_lock); do_not_lock = CRYPTO_THREAD_compare_id(locking_threadid, cur); CRYPTO_THREAD_unlock(rand_tmp_lock); } else do_not_lock = 0; if (!do_not_lock) { CRYPTO_THREAD_write_lock(rand_lock); /* * Prevent deadlocks in case we end up in an async engine */ ASYNC_block_pause(); /* * prevent rand_bytes() from trying to obtain the lock again */ CRYPTO_THREAD_write_lock(rand_tmp_lock); locking_threadid = cur; CRYPTO_THREAD_unlock(rand_tmp_lock); crypto_lock_rand = 1; } if (!initialized) { RAND_poll(); initialized = 1; } ret = entropy >= ENTROPY_NEEDED; if (!do_not_lock) { /* before unlocking, we must clear 'crypto_lock_rand' */ crypto_lock_rand = 0; ASYNC_unblock_pause(); CRYPTO_THREAD_unlock(rand_lock); } return ret; } /* * rand_hw_seed: get seed data from any available hardware RNG. only * currently supports rdrand. */ /* Adapted from eng_rdrand.c */ #if (defined(__i386) || defined(__i386__) || defined(_M_IX86) || \ defined(__x86_64) || defined(__x86_64__) || \ defined(_M_AMD64) || defined (_M_X64)) && defined(OPENSSL_CPUID_OBJ) \ && !defined(OPENSSL_NO_RDRAND) # define RDRAND_CALLS 4 size_t OPENSSL_ia32_rdrand(void); extern unsigned int OPENSSL_ia32cap_P[]; static int rand_hw_seed(EVP_MD_CTX *ctx) { int i; if (!(OPENSSL_ia32cap_P[1] & (1 << (62 - 32)))) return 1; for (i = 0; i < RDRAND_CALLS; i++) { size_t rnd; rnd = OPENSSL_ia32_rdrand(); if (rnd == 0) return 1; if (!MD_Update(ctx, (unsigned char *)&rnd, sizeof(size_t))) return 0; } return 1; } /* XOR an existing buffer with random data */ void rand_hw_xor(unsigned char *buf, size_t num) { size_t rnd; if (!(OPENSSL_ia32cap_P[1] & (1 << (62 - 32)))) return; while (num >= sizeof(size_t)) { rnd = OPENSSL_ia32_rdrand(); if (rnd == 0) return; *((size_t *)buf) ^= rnd; buf += sizeof(size_t); num -= sizeof(size_t); } if (num) { rnd = OPENSSL_ia32_rdrand(); if (rnd == 0) return; while (num) { *buf ^= rnd & 0xff; rnd >>= 8; buf++; num--; } } } #else static int rand_hw_seed(EVP_MD_CTX *ctx) { return 1; } void rand_hw_xor(unsigned char *buf, size_t num) { return; } #endif