diff options
Diffstat (limited to 'util/libreboot-utils/lib/num.c')
| -rw-r--r-- | util/libreboot-utils/lib/num.c | 324 |
1 files changed, 1 insertions, 323 deletions
diff --git a/util/libreboot-utils/lib/num.c b/util/libreboot-utils/lib/num.c index 0b76e257..41a08f0b 100644 --- a/util/libreboot-utils/lib/num.c +++ b/util/libreboot-utils/lib/num.c @@ -2,6 +2,7 @@ * Copyright (c) 2026 Leah Rowe <leah@libreboot.org> * * Numerical functions. + * NOTE: randomness was moved to rand.c */ /* @@ -12,10 +13,6 @@ TODO: properly handle errno in this file #include <sys/param.h> #endif #include <sys/types.h> -#if defined(FALLBACK_RAND_1989) && \ - (FALLBACK_RAND_1989) > 0 -#include <sys/time.h> -#endif #include <errno.h> #if !((defined(__OpenBSD__) && (OpenBSD) >= 201) || \ @@ -26,10 +23,6 @@ TODO: properly handle errno in this file #include <limits.h> #include <stddef.h> #include <string.h> -#if defined(FALLBACK_RAND_1989) && \ - (FALLBACK_RAND_1989) > 0 -#include <time.h> -#endif #include <unistd.h> #include "../include/common.h" @@ -117,321 +110,6 @@ err_hextonum: /* caller just checks >15. */ } -/* Random numbers - */ - -/* when calling this: save errno - * first, then set errno to zero. - * on error, this function will - * set errno and possibly return - * - * rlong also preserves errno - * and leaves it unchanged on - * success, so if you do it - * right, you can detect error. - * this is because it uses - * /dev/urandom which can err. - * ditto getrandom (EINTR), - * theoretically. - */ - -size_t -rlong(void) -{ -#if !(defined(FALLBACK_RAND_1989) && \ - ((FALLBACK_RAND_1989) > 0)) -#if (defined(__OpenBSD__) && (OpenBSD) >= 201) || \ - defined(__FreeBSD__) || \ - defined(__NetBSD__) || defined(__APPLE__) - - int saved_errno = errno; - size_t rval; - - arc4random_buf(&rval, sizeof(size_t)); - - errno = saved_errno; - return rval; -#else - static int fd = -1; - static ssize_t nr = -1; - static size_t off = 0; -#if defined (BUFSIZ) - static char rbuf[BUFSIZ]; -#else -#ifndef PORTABLE - static char rbuf[4096]; -#elif ((PORTABLE) > 0) - static char rbuf[256]; /* scarce memory on old systems */ -#else - static char rbuf[4096]; /* typical 32-bit BUFSIZ */ -#endif -#endif - size_t rval; - ssize_t new_nr; - - int retries = 0; - int max_retries = 100; - - int saved_errno = errno; - -#if defined(__linux__) -#if defined(HAVE_GETRANDOM) || \ - defined(HAVE_GETRANDOM_SYSCALL) - - /* linux getrandom() - * - * we *can* use arc4random on - * modern linux, but not on - * every libc. better use the - * official linux function - */ - - if (fallback_rand_getrandom(&rval, sizeof(rval)) == 0) { - errno = saved_errno; - return rval; - } - - /* - * now fall back to urandom if getrandom failed: - */ -#endif -#endif - - /* reading from urandom is inherently - * unreliable on old systems, even if - * newer systems make it more reliable - * - * modern linux/bsd make it safe, but - * we have to assume that someone is - * compiling this on linux from 1999 - * - * this logic therefore applies various - * tricks to mitigate possible os bugs - */ - -retry_urandom_read: - - if (++retries > max_retries) - goto err_rlong; - - if (nr < 0 || nr < (ssize_t)sizeof(size_t)) { - - if (fd < 0) { - - fd = open("/dev/urandom", - O_RDONLY | O_BINARY | O_NOFOLLOW | - O_CLOEXEC | O_NOCTTY); - -#ifdef USE_OLD_DEV_RANDOM -#if (USE_OLD_DEV_RANDOM) > 0 - /* WARNING: - * /dev/random may block - * forever and does **NOT** - * guarantee better entropy - * on old systems - * - * only use it if needed - */ - - if (fd < 0) - fd = open("/dev/random", - O_RDONLY | O_BINARY | O_NOFOLLOW | - O_CLOEXEC | O_NOCTTY); -#endif -#endif - - if (fd < 0) - goto retry_urandom_read; - - retries = 0; - } - - new_nr = rw_file_exact(fd, (unsigned char *)rbuf, - sizeof(rbuf), 0, IO_READ, LOOP_EAGAIN, - LOOP_EINTR, MAX_ZERO_RW_RETRY, OFF_ERR); - - if (new_nr < 0 || new_nr < (ssize_t)sizeof(rbuf)) - goto retry_urandom_read; - - /* only reset buffer after successful refill */ - nr = new_nr; - off = 0; - - /* don't re-use same fd, to mitaget - * fd injection */ - close_no_err(&fd); - } - - fd = -1; - retries = 0; - - memcpy(&rval, rbuf + off, sizeof(size_t)); - - nr -= (ssize_t)sizeof(size_t); - off += sizeof(size_t); - - errno = saved_errno; - - return rval; - -err_rlong: - - if (errno == saved_errno) - errno = EIO; - - return 0; - -#endif -#else /* FALLBACK_RAND_1989 */ - /* your computer is from a museum - */ - size_t mix = 0; - int nr = 0; - int saved_errno = errno; - - /* 100 times, for entropy - */ - for (nr = 0; nr < 100; nr++) - mix ^= fallback_rand_1989(); - - errno = saved_errno; - return mix; -#endif -} - -#if !(defined(FALLBACK_RAND_1989) && \ - ((FALLBACK_RAND_1989) > 0)) -#if defined(__linux__) -#if defined(HAVE_GETRANDOM) || \ - defined(HAVE_GETRANDOM_SYSCALL) -int /* yes, linux is a fallback */ -fallback_rand_getrandom(void *buf, size_t len) -{ - size_t off = 0; - ssize_t rval = -1; - int saved_errno = errno; - - if (!len) { - errno = EINVAL; - return -1; - } - - if (buf == NULL) { - errno = EFAULT; - return -1; - } - -#if defined(HAVE_GETRANDOM) || \ - defined(HAVE_GETRANDOM_SYSCALL) - - while (off < len) { - -#if defined(HAVE_GETRANDOM) - rval = (ssize_t)getrandom((char *)buf + off, len - off, 0); -#elif defined(HAVE_GETRANDOM_SYSCALL) - rval = (ssize_t)syscall(SYS_getrandom, - (char *)buf + off, len - off, 0); -#endif - - if (rval < 0) { - if (errno == EINTR || errno == EAGAIN) - continue; - - errno = EIO; - return -1; /* unsupported by kernel */ - } - - if (rval == 0) { - errno = EIO; - return -1; - } - - off += (size_t)rval; - } - - errno = saved_errno; - return 0; - -#else - (void)buf; - (void)len; - - errno = EIO; - return -1; -#endif -} -#endif -#endif -#else -size_t -fallback_rand_1989(void) -{ - static size_t mix = 0; - static size_t counter = 0; - - struct timeval tv; - - /* nobody should use this - * (not crypto-safe) - */ - - gettimeofday(&tv, NULL); - - mix ^= (size_t)tv.tv_sec - ^ (size_t)tv.tv_usec - ^ (size_t)getpid() - ^ (size_t)&mix - ^ counter++ - ^ entropy_jitter(); - - /* - * Stack addresses can vary between - * calls, thus increasing entropy. - */ - mix ^= (size_t)&mix; - mix ^= (size_t)&tv; - mix ^= (size_t)&counter; - - return mix; -} - -size_t -entropy_jitter(void) -{ - size_t mix; - - struct timeval a, b; - ssize_t mix_diff; - - int c; - - mix = 0; - - gettimeofday(&a, NULL); - - for (c = 0; c < 32; c++) { - - getpid(); - gettimeofday(&b, NULL); - - /* - * prevent negative numbers to prevent overflow, - * which would bias rand to large numbers - */ - mix_diff = (ssize_t)(b.tv_usec - a.tv_usec); - if (mix_diff < 0) - mix_diff = -mix_diff; - - mix ^= (size_t)(mix_diff); - - mix ^= (size_t)&mix; - - } - - return mix; -} -#endif - void check_bin(size_t a, const char *a_name) { |