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nk/hwrng: Use libc wrapper for getrandom by default.

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Nicholas J. Kain 2022-03-08 13:45:52 -05:00
parent 0b53d93648
commit b21edf205a
1 changed files with 21 additions and 12 deletions
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33
nk/hwrng.c
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@ -1,4 +1,4 @@
// Copyright 2013-2018 Nicholas J. Kain <njkain at gmail dot com> // Copyright 2013-2022 Nicholas J. Kain <njkain at gmail dot com>
// SPDX-License-Identifier: MIT // SPDX-License-Identifier: MIT
#include <stdint.h> #include <stdint.h>
#include <string.h> #include <string.h>
@ -13,22 +13,36 @@
#include "nk/log.h" #include "nk/log.h"
#include "nk/io.h" #include "nk/io.h"
#ifdef NK_USE_GETRANDOM_SYSCALL #ifdef NK_NO_GETRANDOM_SYSCALL
static bool nk_getrandom(char *seed, size_t len)
{
(void)seed;
(void)len;
return false;
}
#else
#ifdef NK_NO_GETRANDOM_LIBC
#include <sys/syscall.h> #include <sys/syscall.h>
#include <linux/random.h> #include <linux/random.h>
#define NK_GETRANDOM_CALL(A,B,C) syscall(SYS_getrandom, (A), (B), (C))
#else
#include <sys/random.h>
#define NK_GETRANDOM_CALL(A,B,C) getrandom((A), (B), (C))
#endif
static bool nk_getrandom(char *seed, size_t len) static bool nk_getrandom(char *seed, size_t len)
{ {
size_t fetched = 0; size_t fetched = 0;
while (fetched < len) { while (fetched < len) {
int r = syscall(SYS_getrandom, seed + fetched, len - fetched, 0); int r = NK_GETRANDOM_CALL(seed + fetched, len - fetched, 0);
if (r <= 0) { if (r <= 0) {
if (r == 0) { if (r == 0) {
// Failsafe to guard against infinite loops. // Failsafe to guard against infinite loops.
log_line("%s: getrandom() returned no entropy", __func__); log_line("%s: getrandom() returned no entropy", __func__);
return false; return false;
} }
if (errno == EINTR) if (errno == EINTR) continue;
continue; if (errno == ENOSYS) return false; // Kernel doesn't support syscall
log_line("%s: getrandom() failed: %s", __func__, strerror(errno)); log_line("%s: getrandom() failed: %s", __func__, strerror(errno));
return false; return false;
} }
@ -36,14 +50,9 @@ static bool nk_getrandom(char *seed, size_t len)
} }
return true; return true;
} }
#else
static bool nk_getrandom(char *seed, size_t len)
{
(void)seed;
(void)len;
return false;
}
#endif #endif
#undef NK_GETRANDOM_CALL
static bool nk_get_rnd_clk(char *seed, size_t len) static bool nk_get_rnd_clk(char *seed, size_t len)
{ {
struct timespec ts; struct timespec ts;