/* * Copyright 1995-2023 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 */ #ifndef _GNU_SOURCE # define _GNU_SOURCE #endif #include "internal/e_os.h" #include #include "internal/cryptlib.h" #include #include #include "crypto/rand_pool.h" #include "crypto/rand.h" #include "internal/dso.h" #include "internal/nelem.h" #include "prov/seeding.h" #ifdef __linux # include # ifdef DEVRANDOM_WAIT # include # include # endif #endif #if (defined(__FreeBSD__) || defined(__NetBSD__)) && !defined(OPENSSL_SYS_UEFI) # include # include # include #endif #if defined(__OpenBSD__) # include #endif #if defined(__DragonFly__) # include # include #endif #if (defined(OPENSSL_SYS_UNIX) && !defined(OPENSSL_SYS_VXWORKS)) \ || defined(__DJGPP__) # include # include # include # include # include static uint64_t get_time_stamp(void); /* Macro to convert two thirty two bit values into a sixty four bit one */ # define TWO32TO64(a, b) ((((uint64_t)(a)) << 32) + (b)) /* * Check for the existence and support of POSIX timers. The standard * says that the _POSIX_TIMERS macro will have a positive value if they * are available. * * However, we want an additional constraint: that the timer support does * not require an extra library dependency. Early versions of glibc * require -lrt to be specified on the link line to access the timers, * so this needs to be checked for. * * It is worse because some libraries define __GLIBC__ but don't * support the version testing macro (e.g. uClibc). This means * an extra check is needed. * * The final condition is: * "have posix timers and either not glibc or glibc without -lrt" * * The nested #if sequences are required to avoid using a parameterised * macro that might be undefined. */ # undef OSSL_POSIX_TIMER_OKAY /* On some systems, _POSIX_TIMERS is defined but empty. * Subtracting by 0 when comparing avoids an error in this case. */ # if defined(_POSIX_TIMERS) && _POSIX_TIMERS -0 > 0 # if defined(__GLIBC__) # if defined(__GLIBC_PREREQ) # if __GLIBC_PREREQ(2, 17) # define OSSL_POSIX_TIMER_OKAY # endif # endif # else # define OSSL_POSIX_TIMER_OKAY # endif # endif #endif /* (defined(OPENSSL_SYS_UNIX) && !defined(OPENSSL_SYS_VXWORKS)) || defined(__DJGPP__) */ #if defined(OPENSSL_RAND_SEED_NONE) /* none means none. this simplifies the following logic */ # undef OPENSSL_RAND_SEED_OS # undef OPENSSL_RAND_SEED_GETRANDOM # undef OPENSSL_RAND_SEED_LIBRANDOM # undef OPENSSL_RAND_SEED_DEVRANDOM # undef OPENSSL_RAND_SEED_RDTSC # undef OPENSSL_RAND_SEED_RDCPU # undef OPENSSL_RAND_SEED_EGD #endif #if defined(OPENSSL_SYS_UEFI) && !defined(OPENSSL_RAND_SEED_NONE) # error "UEFI only supports 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 ossl_pool_acquire_entropy(RAND_POOL *pool) { short int code; 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 bytes_needed = ossl_rand_pool_bytes_needed(pool, 4 /*entropy_factor*/); 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); ossl_rand_pool_add(pool, arg, &v, sizeof(v), 2); } return ossl_rand_pool_entropy_available(pool); } void ossl_rand_pool_cleanup(void) { } void ossl_rand_pool_keep_random_devices_open(int keep) { } # 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_GETRANDOM # define OPENSSL_RAND_SEED_DEVRANDOM # endif # if defined(OPENSSL_RAND_SEED_LIBRANDOM) # error "librandom not (yet) supported" # endif # if (defined(__FreeBSD__) || defined(__NetBSD__)) && defined(KERN_ARND) /* * sysctl_random(): Use sysctl() to read a random number from the kernel * Returns the number of bytes returned in buf on success, -1 on failure. */ static ssize_t sysctl_random(char *buf, size_t buflen) { int mib[2]; size_t done = 0; size_t len; /* * Note: sign conversion between size_t and ssize_t is safe even * without a range check, see comment in syscall_random() */ /* * On FreeBSD old implementations returned longs, newer versions support * variable sizes up to 256 byte. The code below would not work properly * when the sysctl returns long and we want to request something not a * multiple of longs, which should never be the case. */ #if defined(__FreeBSD__) if (!ossl_assert(buflen % sizeof(long) == 0)) { errno = EINVAL; return -1; } #endif /* * On NetBSD before 4.0 KERN_ARND was an alias for KERN_URND, and only * filled in an int, leaving the rest uninitialized. Since NetBSD 4.0 * it returns a variable number of bytes with the current version supporting * up to 256 bytes. * Just return an error on older NetBSD versions. */ #if defined(__NetBSD__) && __NetBSD_Version__ < 400000000 errno = ENOSYS; return -1; #endif mib[0] = CTL_KERN; mib[1] = KERN_ARND; do { len = buflen > 256 ? 256 : buflen; if (sysctl(mib, 2, buf, &len, NULL, 0) == -1) return done > 0 ? done : -1; done += len; buf += len; buflen -= len; } while (buflen > 0); return done; } # endif # if defined(OPENSSL_RAND_SEED_GETRANDOM) # if defined(__linux) && !defined(__NR_getrandom) # if defined(__arm__) # define __NR_getrandom (__NR_SYSCALL_BASE+384) # elif defined(__i386__) # define __NR_getrandom 355 # elif defined(__x86_64__) # if defined(__ILP32__) # define __NR_getrandom (__X32_SYSCALL_BIT + 318) # else # define __NR_getrandom 318 # endif # elif defined(__xtensa__) # define __NR_getrandom 338 # elif defined(__s390__) || defined(__s390x__) # define __NR_getrandom 349 # elif defined(__bfin__) # define __NR_getrandom 389 # elif defined(__powerpc__) # define __NR_getrandom 359 # elif defined(__mips__) || defined(__mips64) # if _MIPS_SIM == _MIPS_SIM_ABI32 # define __NR_getrandom (__NR_Linux + 353) # elif _MIPS_SIM == _MIPS_SIM_ABI64 # define __NR_getrandom (__NR_Linux + 313) # elif _MIPS_SIM == _MIPS_SIM_NABI32 # define __NR_getrandom (__NR_Linux + 317) # endif # elif defined(__hppa__) # define __NR_getrandom (__NR_Linux + 339) # elif defined(__sparc__) # define __NR_getrandom 347 # elif defined(__ia64__) # define __NR_getrandom 1339 # elif defined(__alpha__) # define __NR_getrandom 511 # elif defined(__sh__) # if defined(__SH5__) # define __NR_getrandom 373 # else # define __NR_getrandom 384 # endif # elif defined(__avr32__) # define __NR_getrandom 317 # elif defined(__microblaze__) # define __NR_getrandom 385 # elif defined(__m68k__) # define __NR_getrandom 352 # elif defined(__cris__) # define __NR_getrandom 356 # else /* generic (f.e. aarch64, loongarch, loongarch64) */ # define __NR_getrandom 278 # endif # endif /* * syscall_random(): Try to get random data using a system call * returns the number of bytes returned in buf, or < 0 on error. */ static ssize_t syscall_random(void *buf, size_t buflen) { /* * Note: 'buflen' equals the size of the buffer which is used by the * get_entropy() callback of the RAND_DRBG. It is roughly bounded by * * 2 * RAND_POOL_FACTOR * (RAND_DRBG_STRENGTH / 8) = 2^14 * * which is way below the OSSL_SSIZE_MAX limit. Therefore sign conversion * between size_t and ssize_t is safe even without a range check. */ /* * Do runtime detection to find getentropy(). * * Known OSs that should support this: * - Darwin since 16 (OSX 10.12, IOS 10.0). * - Solaris since 11.3 * - OpenBSD since 5.6 * - Linux since 3.17 with glibc 2.25 * - FreeBSD since 12.0 (1200061) * * Note: Sometimes getentropy() can be provided but not implemented * internally. So we need to check errno for ENOSYS */ # if !defined(__DragonFly__) && !defined(__NetBSD__) # if defined(__GNUC__) && __GNUC__>=2 && defined(__ELF__) && !defined(__hpux) extern int getentropy(void *buffer, size_t length) __attribute__((weak)); if (getentropy != NULL) { if (getentropy(buf, buflen) == 0) return (ssize_t)buflen; if (errno != ENOSYS) return -1; } # elif defined(OPENSSL_APPLE_CRYPTO_RANDOM) if (CCRandomGenerateBytes(buf, buflen) == kCCSuccess) return (ssize_t)buflen; return -1; # else union { void *p; int (*f)(void *buffer, size_t length); } p_getentropy; /* * We could cache the result of the lookup, but we normally don't * call this function often. */ ERR_set_mark(); p_getentropy.p = DSO_global_lookup("getentropy"); ERR_pop_to_mark(); if (p_getentropy.p != NULL) return p_getentropy.f(buf, buflen) == 0 ? (ssize_t)buflen : -1; # endif # endif /* !__DragonFly__ */ /* Linux supports this since version 3.17 */ # if defined(__linux) && defined(__NR_getrandom) return syscall(__NR_getrandom, buf, buflen, 0); # elif (defined(__FreeBSD__) || defined(__NetBSD__)) && defined(KERN_ARND) return sysctl_random(buf, buflen); # elif (defined(__DragonFly__) && __DragonFly_version >= 500700) \ || (defined(__NetBSD__) && __NetBSD_Version >= 1000000000) return getrandom(buf, buflen, 0); # elif defined(__wasi__) if (getentropy(buf, buflen) == 0) return (ssize_t)buflen; return -1; # else errno = ENOSYS; return -1; # endif } # endif /* defined(OPENSSL_RAND_SEED_GETRANDOM) */ # if defined(OPENSSL_RAND_SEED_DEVRANDOM) static const char *random_device_paths[] = { DEVRANDOM }; static struct random_device { int fd; dev_t dev; ino_t ino; mode_t mode; dev_t rdev; } random_devices[OSSL_NELEM(random_device_paths)]; static int keep_random_devices_open = 1; # if defined(__linux) && defined(DEVRANDOM_WAIT) \ && defined(OPENSSL_RAND_SEED_GETRANDOM) static void *shm_addr; static void cleanup_shm(void) { shmdt(shm_addr); } /* * Ensure that the system randomness source has been adequately seeded. * This is done by having the first start of libcrypto, wait until the device * /dev/random becomes able to supply a byte of entropy. Subsequent starts * of the library and later reseedings do not need to do this. */ static int wait_random_seeded(void) { static int seeded = OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID < 0; static const int kernel_version[] = { DEVRANDOM_SAFE_KERNEL }; int kernel[2]; int shm_id, fd, r; char c, *p; struct utsname un; fd_set fds; if (!seeded) { /* See if anything has created the global seeded indication */ if ((shm_id = shmget(OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID, 1, 0)) == -1) { /* * Check the kernel's version and fail if it is too recent. * * Linux kernels from 4.8 onwards do not guarantee that * /dev/urandom is properly seeded when /dev/random becomes * readable. However, such kernels support the getentropy(2) * system call and this should always succeed which renders * this alternative but essentially identical source moot. */ if (uname(&un) == 0) { kernel[0] = atoi(un.release); p = strchr(un.release, '.'); kernel[1] = p == NULL ? 0 : atoi(p + 1); if (kernel[0] > kernel_version[0] || (kernel[0] == kernel_version[0] && kernel[1] >= kernel_version[1])) { return 0; } } /* Open /dev/random and wait for it to be readable */ if ((fd = open(DEVRANDOM_WAIT, O_RDONLY)) != -1) { if (DEVRANDM_WAIT_USE_SELECT && fd < FD_SETSIZE) { FD_ZERO(&fds); FD_SET(fd, &fds); while ((r = select(fd + 1, &fds, NULL, NULL, NULL)) < 0 && errno == EINTR); } else { while ((r = read(fd, &c, 1)) < 0 && errno == EINTR); } close(fd); if (r == 1) { seeded = 1; /* Create the shared memory indicator */ shm_id = shmget(OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID, 1, IPC_CREAT | S_IRUSR | S_IRGRP | S_IROTH); } } } if (shm_id != -1) { seeded = 1; /* * Map the shared memory to prevent its premature destruction. * If this call fails, it isn't a big problem. */ shm_addr = shmat(shm_id, NULL, SHM_RDONLY); if (shm_addr != (void *)-1) OPENSSL_atexit(&cleanup_shm); } } return seeded; } # else /* defined __linux && DEVRANDOM_WAIT && OPENSSL_RAND_SEED_GETRANDOM */ static int wait_random_seeded(void) { return 1; } # endif /* * Verify that the file descriptor associated with the random source is * still valid. The rationale for doing this is the fact that it is not * uncommon for daemons to close all open file handles when daemonizing. * So the handle might have been closed or even reused for opening * another file. */ static int check_random_device(struct random_device *rd) { struct stat st; return rd->fd != -1 && fstat(rd->fd, &st) != -1 && rd->dev == st.st_dev && rd->ino == st.st_ino && ((rd->mode ^ st.st_mode) & ~(S_IRWXU | S_IRWXG | S_IRWXO)) == 0 && rd->rdev == st.st_rdev; } /* * Open a random device if required and return its file descriptor or -1 on error */ static int get_random_device(size_t n) { struct stat st; struct random_device *rd = &random_devices[n]; /* reuse existing file descriptor if it is (still) valid */ if (check_random_device(rd)) return rd->fd; /* open the random device ... */ if ((rd->fd = open(random_device_paths[n], O_RDONLY)) == -1) return rd->fd; /* ... and cache its relevant stat(2) data */ if (fstat(rd->fd, &st) != -1) { rd->dev = st.st_dev; rd->ino = st.st_ino; rd->mode = st.st_mode; rd->rdev = st.st_rdev; } else { close(rd->fd); rd->fd = -1; } return rd->fd; } /* * Close a random device making sure it is a random device */ static void close_random_device(size_t n) { struct random_device *rd = &random_devices[n]; if (check_random_device(rd)) close(rd->fd); rd->fd = -1; } int ossl_rand_pool_init(void) { size_t i; for (i = 0; i < OSSL_NELEM(random_devices); i++) random_devices[i].fd = -1; return 1; } void ossl_rand_pool_cleanup(void) { size_t i; for (i = 0; i < OSSL_NELEM(random_devices); i++) close_random_device(i); } void ossl_rand_pool_keep_random_devices_open(int keep) { if (!keep) ossl_rand_pool_cleanup(); keep_random_devices_open = keep; } # else /* !defined(OPENSSL_RAND_SEED_DEVRANDOM) */ int ossl_rand_pool_init(void) { return 1; } void ossl_rand_pool_cleanup(void) { } void ossl_rand_pool_keep_random_devices_open(int keep) { } # endif /* defined(OPENSSL_RAND_SEED_DEVRANDOM) */ /* * Try the various seeding methods in turn, exit when successful. * * 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 ossl_pool_acquire_entropy(RAND_POOL *pool) { # if defined(OPENSSL_RAND_SEED_NONE) return ossl_rand_pool_entropy_available(pool); # else size_t entropy_available = 0; (void)entropy_available; /* avoid compiler warning */ # if defined(OPENSSL_RAND_SEED_GETRANDOM) { size_t bytes_needed; unsigned char *buffer; ssize_t bytes; /* Maximum allowed number of consecutive unsuccessful attempts */ int attempts = 3; bytes_needed = ossl_rand_pool_bytes_needed(pool, 1 /*entropy_factor*/); while (bytes_needed != 0 && attempts-- > 0) { buffer = ossl_rand_pool_add_begin(pool, bytes_needed); bytes = syscall_random(buffer, bytes_needed); if (bytes > 0) { ossl_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 = ossl_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) if (wait_random_seeded()) { size_t bytes_needed; unsigned char *buffer; size_t i; bytes_needed = ossl_rand_pool_bytes_needed(pool, 1 /*entropy_factor*/); for (i = 0; bytes_needed > 0 && i < OSSL_NELEM(random_device_paths); i++) { ssize_t bytes = 0; /* Maximum 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 = ossl_rand_pool_add_begin(pool, bytes_needed); bytes = read(fd, buffer, bytes_needed); if (bytes > 0) { ossl_rand_pool_add_end(pool, bytes, 8 * bytes); bytes_needed -= bytes; attempts = 3; /* reset counter on successful attempt */ } else if (bytes < 0 && errno != EINTR) { break; } } if (bytes < 0 || !keep_random_devices_open) close_random_device(i); bytes_needed = ossl_rand_pool_bytes_needed(pool, 1); } entropy_available = ossl_rand_pool_entropy_available(pool); if (entropy_available > 0) return entropy_available; } # endif # if defined(OPENSSL_RAND_SEED_RDTSC) entropy_available = ossl_prov_acquire_entropy_from_tsc(pool); if (entropy_available > 0) return entropy_available; # endif # if defined(OPENSSL_RAND_SEED_RDCPU) entropy_available = ossl_prov_acquire_entropy_from_cpu(pool); if (entropy_available > 0) return entropy_available; # endif # if defined(OPENSSL_RAND_SEED_EGD) { static const char *paths[] = { DEVRANDOM_EGD, NULL }; size_t bytes_needed; unsigned char *buffer; int i; bytes_needed = ossl_rand_pool_bytes_needed(pool, 1 /*entropy_factor*/); for (i = 0; bytes_needed > 0 && paths[i] != NULL; i++) { size_t bytes = 0; int num; buffer = ossl_rand_pool_add_begin(pool, bytes_needed); num = RAND_query_egd_bytes(paths[i], buffer, (int)bytes_needed); if (num == (int)bytes_needed) bytes = bytes_needed; ossl_rand_pool_add_end(pool, bytes, 8 * bytes); bytes_needed = ossl_rand_pool_bytes_needed(pool, 1); } entropy_available = ossl_rand_pool_entropy_available(pool); if (entropy_available > 0) return entropy_available; } # endif return ossl_rand_pool_entropy_available(pool); # endif } # endif #endif #if (defined(OPENSSL_SYS_UNIX) && !defined(OPENSSL_SYS_VXWORKS)) \ || defined(__DJGPP__) int ossl_pool_add_nonce_data(RAND_POOL *pool) { struct { pid_t pid; CRYPTO_THREAD_ID tid; uint64_t time; } data; /* Erase the entire structure including any padding */ memset(&data, 0, sizeof(data)); /* * Add process id, thread id, and a high resolution timestamp to * ensure that the nonce is unique with high probability for * different process instances. */ data.pid = getpid(); data.tid = CRYPTO_THREAD_get_current_id(); data.time = get_time_stamp(); return ossl_rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0); } /* * Get the current time with the highest possible resolution * * The time stamp is added to the nonce, so it is optimized for not repeating. * The current time is ideal for this purpose, provided the computer's clock * is synchronized. */ static uint64_t get_time_stamp(void) { # if defined(OSSL_POSIX_TIMER_OKAY) { struct timespec ts; if (clock_gettime(CLOCK_REALTIME, &ts) == 0) return TWO32TO64(ts.tv_sec, ts.tv_nsec); } # endif # if defined(__unix__) \ || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L) { struct timeval tv; if (gettimeofday(&tv, NULL) == 0) return TWO32TO64(tv.tv_sec, tv.tv_usec); } # endif return time(NULL); } #endif /* (defined(OPENSSL_SYS_UNIX) && !defined(OPENSSL_SYS_VXWORKS)) || defined(__DJGPP__) */