openssh/openbsd-compat/bsd-getentropy.c
Darren Tucker da6038bd5c
Always use compat getentropy.
Have it call native getentropy and fall back as required.  Should fix
issues of platforms where libc has getentropy but it is not implemented
in the kernel.  Based on github PR#354 from simsergey.
2022-11-02 12:20:50 +11:00

84 lines
2.2 KiB
C

/*
* Copyright (c) 1996, David Mazieres <dm@uun.org>
* Copyright (c) 2008, Damien Miller <djm@openbsd.org>
* Copyright (c) 2013, Markus Friedl <markus@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "includes.h"
#ifndef SSH_RANDOM_DEV
# define SSH_RANDOM_DEV "/dev/urandom"
#endif /* SSH_RANDOM_DEV */
#include <sys/types.h>
#ifdef HAVE_SYS_RANDOM_H
# include <sys/random.h>
#endif
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifdef WITH_OPENSSL
#include <openssl/rand.h>
#include <openssl/err.h>
#endif
#include "log.h"
int
_ssh_compat_getentropy(void *s, size_t len)
{
#ifdef WITH_OPENSSL
if (RAND_bytes(s, len) <= 0)
fatal("Couldn't obtain random bytes (error 0x%lx)",
(unsigned long)ERR_get_error());
#else
int fd, save_errno;
ssize_t r;
size_t o = 0;
#ifdef HAVE_GETENTROPY
if (r = getentropy(s, len) == 0)
return 0;
#endif /* HAVE_GETENTROPY */
#ifdef HAVE_GETRANDOM
if ((r = getrandom(s, len, 0)) > 0 && (size_t)r == len)
return 0;
#endif /* HAVE_GETRANDOM */
if ((fd = open(SSH_RANDOM_DEV, O_RDONLY)) == -1) {
save_errno = errno;
/* Try egd/prngd before giving up. */
if (seed_from_prngd(s, len) == 0)
return 0;
fatal("Couldn't open %s: %s", SSH_RANDOM_DEV,
strerror(save_errno));
}
while (o < len) {
r = read(fd, (u_char *)s + o, len - o);
if (r < 0) {
if (errno == EAGAIN || errno == EINTR ||
errno == EWOULDBLOCK)
continue;
fatal("read %s: %s", SSH_RANDOM_DEV, strerror(errno));
}
o += r;
}
close(fd);
#endif /* WITH_OPENSSL */
return 0;
}