/* * Copyright 1995-2018 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 "e_os.h" #include #include "internal/cryptlib.h" #include #include "rand_lcl.h" #include "internal/rand_int.h" #include #if (defined(OPENSSL_SYS_VXWORKS) || defined(OPENSSL_SYS_UEFI)) && \ !defined(OPENSSL_RAND_SEED_NONE) # error "UEFI and VXWorks only support seeding NONE" #endif #if !(defined(OPENSSL_SYS_WINDOWS) || defined(OPENSSL_SYS_WIN32) \ || defined(OPENSSL_SYS_VMS) || defined(OPENSSL_SYS_VXWORKS) \ || defined(OPENSSL_SYS_UEFI)) # if defined(OPENSSL_SYS_VOS) # ifndef OPENSSL_RAND_SEED_OS # error "Unsupported seeding method configured; must be os" # endif # if defined(OPENSSL_SYS_VOS_HPPA) && defined(OPENSSL_SYS_VOS_IA32) # error "Unsupported HP-PA and IA32 at the same time." # endif # if !defined(OPENSSL_SYS_VOS_HPPA) && !defined(OPENSSL_SYS_VOS_IA32) # error "Must have one of HP-PA or IA32" # endif /* * The following algorithm repeatedly samples the real-time clock (RTC) to * generate a sequence of unpredictable data. The algorithm relies upon the * uneven execution speed of the code (due to factors such as cache misses, * interrupts, bus activity, and scheduling) and upon the rather large * relative difference between the speed of the clock and the rate at which * it can be read. If it is ported to an environment where execution speed * is more constant or where the RTC ticks at a much slower rate, or the * clock can be read with fewer instructions, it is likely that the results * would be far more predictable. This should only be used for legacy * platforms. * * As a precaution, we assume only 2 bits of entropy per byte. */ size_t rand_pool_acquire_entropy(RAND_POOL *pool) { short int code; gid_t curr_gid; pid_t curr_pid; uid_t curr_uid; int i, k; size_t bytes_needed; struct timespec ts; unsigned char v; # ifdef OPENSSL_SYS_VOS_HPPA long duration; extern void s$sleep(long *_duration, short int *_code); # else long long duration; extern void s$sleep2(long long *_duration, short int *_code); # endif /* * Seed with the gid, pid, and uid, to ensure *some* variation between * different processes. */ curr_gid = getgid(); rand_pool_add(pool, &curr_gid, sizeof(curr_gid), 0); curr_pid = getpid(); rand_pool_add(pool, &curr_pid, sizeof(curr_pid), 0); curr_uid = getuid(); rand_pool_add(pool, &curr_uid, sizeof(curr_uid), 0); bytes_needed = rand_pool_bytes_needed(pool, 2 /*entropy_per_byte*/); for (i = 0; i < bytes_needed; i++) { /* * burn some cpu; hope for interrupts, cache collisions, bus * interference, etc. */ for (k = 0; k < 99; k++) ts.tv_nsec = random(); # ifdef OPENSSL_SYS_VOS_HPPA /* sleep for 1/1024 of a second (976 us). */ duration = 1; s$sleep(&duration, &code); # else /* sleep for 1/65536 of a second (15 us). */ duration = 1; s$sleep2(&duration, &code); # endif /* Get wall clock time, take 8 bits. */ clock_gettime(CLOCK_REALTIME, &ts); v = (unsigned char)(ts.tv_nsec & 0xFF); rand_pool_add(pool, arg, &v, sizeof(v) , 2); } return rand_pool_entropy_available(pool); } # else # if defined(OPENSSL_RAND_SEED_EGD) && \ (defined(OPENSSL_NO_EGD) || !defined(DEVRANDOM_EGD)) # error "Seeding uses EGD but EGD is turned off or no device given" # endif # if defined(OPENSSL_RAND_SEED_DEVRANDOM) && !defined(DEVRANDOM) # error "Seeding uses urandom but DEVRANDOM is not configured" # endif # if defined(OPENSSL_RAND_SEED_OS) # if !defined(DEVRANDOM) # error "OS seeding requires DEVRANDOM to be configured" # endif # define OPENSSL_RAND_SEED_DEVRANDOM # if defined(__GLIBC__) && defined(__GLIBC_PREREQ) # if __GLIBC_PREREQ(2, 25) # define OPENSSL_RAND_SEED_GETRANDOM # endif # endif # endif # ifdef OPENSSL_RAND_SEED_GETRANDOM # include # endif # if defined(OPENSSL_RAND_SEED_LIBRANDOM) # error "librandom not (yet) supported" # 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) { # 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, 8 /*entropy_per_byte*/); buffer = rand_pool_add_begin(pool, bytes_needed); if (buffer != NULL) { size_t bytes = 0; if (getrandom(buffer, bytes_needed, 0) == (int)bytes_needed) bytes = bytes_needed; entropy_available = rand_pool_add_end(pool, bytes, 8 * bytes); } 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, 8 /*entropy_per_byte*/); if (bytes_needed > 0) { static const char *paths[] = { DEVRANDOM, NULL }; FILE *fp; int i; for (i = 0; paths[i] != NULL; i++) { if ((fp = fopen(paths[i], "rb")) == NULL) continue; setbuf(fp, NULL); buffer = rand_pool_add_begin(pool, bytes_needed); if (buffer != NULL) { size_t bytes = 0; if (fread(buffer, 1, bytes_needed, fp) == bytes_needed) bytes = bytes_needed; entropy_available = rand_pool_add_end(pool, bytes, 8 * bytes); } fclose(fp); if (entropy_available > 0) return entropy_available; bytes_needed = rand_pool_bytes_needed(pool, 8 /*entropy_per_byte*/); } } # 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, 8 /*entropy_per_byte*/); 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; entropy_available = rand_pool_add_end(pool, bytes, 8 * bytes); } if (entropy_available > 0) return entropy_available; } } # endif return rand_pool_entropy_available(pool); # endif } # endif #endif