1 /*
2 * Copyright (c) 1996, David Mazieres <dm@uun.org>
3 * Copyright (c) 2008, Damien Miller <djm@openbsd.org>
4 * Copyright (c) 2013, Markus Friedl <markus@openbsd.org>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19 #include "includes.h"
20
21 #ifndef SSH_RANDOM_DEV
22 # define SSH_RANDOM_DEV "/dev/urandom"
23 #endif /* SSH_RANDOM_DEV */
24
25 #include <sys/types.h>
26 #ifdef HAVE_SYS_RANDOM_H
27 # include <sys/random.h>
28 #endif
29
30 #include <fcntl.h>
31 #include <stdlib.h>
32 #include <string.h>
33 #include <unistd.h>
34 #ifdef WITH_OPENSSL
35 #include <openssl/rand.h>
36 #include <openssl/err.h>
37 #endif
38
39 #include "log.h"
40
41 int
_ssh_compat_getentropy(void * s,size_t len)42 _ssh_compat_getentropy(void *s, size_t len)
43 {
44 #if defined(WITH_OPENSSL) && defined(OPENSSL_PRNG_ONLY)
45 if (RAND_bytes(s, len) <= 0)
46 fatal("Couldn't obtain random bytes (error 0x%lx)",
47 (unsigned long)ERR_get_error());
48 #else
49 int fd, save_errno;
50 ssize_t r;
51 size_t o = 0;
52
53 #ifdef WITH_OPENSSL
54 if (RAND_bytes(s, len) == 1)
55 return 0;
56 #endif
57 #ifdef HAVE_GETENTROPY
58 if ((r = getentropy(s, len)) == 0)
59 return 0;
60 #endif /* HAVE_GETENTROPY */
61 #ifdef HAVE_GETRANDOM
62 if ((r = getrandom(s, len, 0)) > 0 && (size_t)r == len)
63 return 0;
64 #endif /* HAVE_GETRANDOM */
65
66 if ((fd = open(SSH_RANDOM_DEV, O_RDONLY)) == -1) {
67 save_errno = errno;
68 /* Try egd/prngd before giving up. */
69 if (seed_from_prngd(s, len) == 0)
70 return 0;
71 fatal("Couldn't open %s: %s", SSH_RANDOM_DEV,
72 strerror(save_errno));
73 }
74 while (o < len) {
75 r = read(fd, (u_char *)s + o, len - o);
76 if (r < 0) {
77 if (errno == EAGAIN || errno == EINTR ||
78 errno == EWOULDBLOCK)
79 continue;
80 fatal("read %s: %s", SSH_RANDOM_DEV, strerror(errno));
81 }
82 o += r;
83 }
84 close(fd);
85 #endif /* WITH_OPENSSL */
86 return 0;
87 }
88