1 /* $OpenBSD: arc4random.h,v 1.4 2015/01/15 06:57:18 deraadt Exp $ */
2
3 /*
4 * Copyright (c) 1996, David Mazieres <dm@uun.org>
5 * Copyright (c) 2008, Damien Miller <djm@openbsd.org>
6 * Copyright (c) 2013, Markus Friedl <markus@openbsd.org>
7 * Copyright (c) 2014, Theo de Raadt <deraadt@openbsd.org>
8 *
9 * Permission to use, copy, modify, and distribute this software for any
10 * purpose with or without fee is hereby granted, provided that the above
11 * copyright notice and this permission notice appear in all copies.
12 *
13 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
14 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
15 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
16 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
17 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
18 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
19 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
20 */
21
22 /*
23 * Stub functions for portability.
24 */
25 #ifndef ARC4RANDOM_H
26 #define ARC4RANDOM_H
27
28 #include <sys/mman.h>
29
30 #include <pthread.h>
31 #include <signal.h>
32
33 static pthread_mutex_t arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;
34 #define _ARC4_LOCK() pthread_mutex_lock(&arc4random_mtx)
35 #define _ARC4_UNLOCK() pthread_mutex_unlock(&arc4random_mtx)
36
37 /*
38 * Unfortunately, pthread_atfork() is broken on FreeBSD (at least 9 and 10) if
39 * a program does not link to -lthr. Callbacks registered with pthread_atfork()
40 * appear to fail silently. So, it is not always possible to detect a PID
41 * wraparound.
42 */
43 #define _ARC4_ATFORK(f) pthread_atfork(NULL, NULL, (f))
44
45 static inline void
_getentropy_fail(void)46 _getentropy_fail(void)
47 {
48 raise(SIGKILL);
49 }
50
51 static volatile sig_atomic_t _rs_forked;
52
53 static inline void
_rs_forkhandler(void)54 _rs_forkhandler(void)
55 {
56 _rs_forked = 1;
57 }
58
59 static inline void
_rs_forkdetect(void)60 _rs_forkdetect(void)
61 {
62 static pid_t _rs_pid = 0;
63 pid_t pid = getpid();
64
65 if (_rs_pid == 0 || _rs_pid != pid || _rs_forked) {
66 _rs_pid = pid;
67 _rs_forked = 0;
68 if (rs)
69 memset(rs, 0, sizeof(*rs));
70 }
71 }
72
73 static inline int
_rs_allocate(struct _rs **rsp, struct _rsx **rsxp)74 _rs_allocate(struct _rs **rsp, struct _rsx **rsxp)
75 {
76 if ((*rsp = mmap(NULL, sizeof(**rsp), PROT_READ|PROT_WRITE,
77 MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED)
78 return (-1);
79
80 if ((*rsxp = mmap(NULL, sizeof(**rsxp), PROT_READ|PROT_WRITE,
81 MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED) {
82 munmap(*rsp, sizeof(**rsp));
83 *rsp = NULL;
84 return (-1);
85 }
86
87 _ARC4_ATFORK(_rs_forkhandler);
88 return (0);
89 }
90 #endif