/* * Try the various seeding methods in turn, exit when successful. * * TODO(DRBG): If more than one entropy source is available, is it * preferable to stop as soon as enough entropy has been collected * (as favored by @rsalz) or should one rather be defensive and add * more entropy than requested and/or from different sources? * * Currently, the user can select multiple entropy sources in the * configure step, yet in practice only the first available source * will be used. A more flexible solution has been requested, but * currently it is not clear how this can be achieved without * overengineering the problem. There are many parameters which * could be taken into account when selecting the order and amount * of input from the different entropy sources (trust, quality, * possibility of blocking). */ size_t rand_pool_acquire_entropy(RAND_POOL *pool) { # ifdef OPENSSL_RAND_SEED_NONE return rand_pool_entropy_available(pool); # else size_t bytes_needed; size_t entropy_available = 0; unsigned char *buffer; # ifdef OPENSSL_RAND_SEED_GETRANDOM bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/); buffer = rand_pool_add_begin(pool, bytes_needed); if (buffer != NULL) { size_t bytes = 0; if (syscall_random(buffer, bytes_needed) == (int)bytes_needed) bytes = bytes_needed; rand_pool_add_end(pool, bytes, 8 * bytes); entropy_available = rand_pool_entropy_available(pool); } if (entropy_available > 0) return entropy_available; # endif # if defined(OPENSSL_RAND_SEED_LIBRANDOM) { /* Not yet implemented. */ } # endif # ifdef OPENSSL_RAND_SEED_DEVRANDOM bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/); { size_t i; for (i = 0; bytes_needed > 0 && i < OSSL_NELEM(random_device_paths); i++) { const int fd = get_random_device(i); if (fd == -1) continue; buffer = rand_pool_add_begin(pool, bytes_needed); if (buffer != NULL) { const ssize_t n = read(fd, buffer, bytes_needed); if (n <= 0) { close_random_device(i); continue; } rand_pool_add_end(pool, n, 8 * n); } if (!keep_random_devices_open) close_random_device(i); bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/); } entropy_available = rand_pool_entropy_available(pool); if (entropy_available > 0) return entropy_available; } # endif # ifdef OPENSSL_RAND_SEED_RDTSC entropy_available = rand_acquire_entropy_from_tsc(pool); if (entropy_available > 0) return entropy_available; # endif # ifdef OPENSSL_RAND_SEED_RDCPU entropy_available = rand_acquire_entropy_from_cpu(pool); if (entropy_available > 0) return entropy_available; # endif # ifdef OPENSSL_RAND_SEED_EGD bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/); if (bytes_needed > 0) { static const char *paths[] = { DEVRANDOM_EGD, NULL }; int i; for (i = 0; paths[i] != NULL; i++) { buffer = rand_pool_add_begin(pool, bytes_needed); if (buffer != NULL) { size_t bytes = 0; int num = RAND_query_egd_bytes(paths[i], buffer, (int)bytes_needed); if (num == (int)bytes_needed) bytes = bytes_needed; rand_pool_add_end(pool, bytes, 8 * bytes); entropy_available = rand_pool_entropy_available(pool); } if (entropy_available > 0) return entropy_available; } } # endif return rand_pool_entropy_available(pool); # endif }
/* * Try the various seeding methods in turn, exit when successful. * * TODO(DRBG): If more than one entropy source is available, is it * preferable to stop as soon as enough entropy has been collected * (as favored by @rsalz) or should one rather be defensive and add * more entropy than requested and/or from different sources? * * Currently, the user can select multiple entropy sources in the * configure step, yet in practice only the first available source * will be used. A more flexible solution has been requested, but * currently it is not clear how this can be achieved without * overengineering the problem. There are many parameters which * could be taken into account when selecting the order and amount * of input from the different entropy sources (trust, quality, * possibility of blocking). */ size_t rand_pool_acquire_entropy(RAND_POOL *pool) { # if defined(OPENSSL_RAND_SEED_NONE) return rand_pool_entropy_available(pool); # else size_t bytes_needed; size_t entropy_available = 0; unsigned char *buffer; # if defined(OPENSSL_RAND_SEED_GETRANDOM) { ssize_t bytes; /* Maximum allowed number of consecutive unsuccessful attempts */ int attempts = 3; bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/); while (bytes_needed != 0 && attempts-- > 0) { buffer = rand_pool_add_begin(pool, bytes_needed); bytes = syscall_random(buffer, bytes_needed); if (bytes > 0) { rand_pool_add_end(pool, bytes, 8 * bytes); bytes_needed -= bytes; attempts = 3; /* reset counter after successful attempt */ } else if (bytes < 0 && errno != EINTR) { break; } } } entropy_available = rand_pool_entropy_available(pool); if (entropy_available > 0) return entropy_available; # endif # if defined(OPENSSL_RAND_SEED_LIBRANDOM) { /* Not yet implemented. */ } # endif # if defined(OPENSSL_RAND_SEED_DEVRANDOM) bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/); { size_t i; for (i = 0; bytes_needed > 0 && i < OSSL_NELEM(random_device_paths); i++) { ssize_t bytes = 0; /* Maximum allowed number of consecutive unsuccessful attempts */ int attempts = 3; const int fd = get_random_device(i); if (fd == -1) continue; while (bytes_needed != 0 && attempts-- > 0) { buffer = rand_pool_add_begin(pool, bytes_needed); bytes = read(fd, buffer, bytes_needed); if (bytes > 0) { rand_pool_add_end(pool, bytes, 8 * bytes); bytes_needed -= bytes; attempts = 3; /* reset counter after successful attempt */ } else if (bytes < 0 && errno != EINTR) { break; } } if (bytes < 0 || !keep_random_devices_open) close_random_device(i); bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/); } entropy_available = rand_pool_entropy_available(pool); if (entropy_available > 0) return entropy_available; } # endif # if defined(OPENSSL_RAND_SEED_RDTSC) entropy_available = rand_acquire_entropy_from_tsc(pool); if (entropy_available > 0) return entropy_available; # endif # if defined(OPENSSL_RAND_SEED_RDCPU) entropy_available = rand_acquire_entropy_from_cpu(pool); if (entropy_available > 0) return entropy_available; # endif # if defined(OPENSSL_RAND_SEED_EGD) bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/); if (bytes_needed > 0) { static const char *paths[] = { DEVRANDOM_EGD, NULL }; int i; for (i = 0; paths[i] != NULL; i++) { buffer = rand_pool_add_begin(pool, bytes_needed); if (buffer != NULL) { size_t bytes = 0; int num = RAND_query_egd_bytes(paths[i], buffer, (int)bytes_needed); if (num == (int)bytes_needed) bytes = bytes_needed; rand_pool_add_end(pool, bytes, 8 * bytes); entropy_available = rand_pool_entropy_available(pool); } if (entropy_available > 0) return entropy_available; } } # endif return rand_pool_entropy_available(pool); # endif }