1 /*	$OpenBSD: arc4random_freebsd.h,v 1.1 2014/11/03 06:23:30 bcook 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  *
8  * Permission to use, copy, modify, and distribute this software for any
9  * purpose with or without fee is hereby granted, provided that the above
10  * copyright notice and this permission notice appear in all copies.
11  *
12  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
13  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
14  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
15  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
16  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
17  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
18  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
19  */
20 
21 /*
22  * Stub functions for portability.
23  */
24 
25 #include <sys/mman.h>
26 
27 #include <pthread.h>
28 #include <signal.h>
29 
30 static pthread_mutex_t arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;
31 #define _ARC4_LOCK()   pthread_mutex_lock(&arc4random_mtx)
32 #define _ARC4_UNLOCK() pthread_mutex_unlock(&arc4random_mtx)
33 
34 /*
35  * Unfortunately, pthread_atfork() is broken on FreeBSD (at least 9 and 10) if
36  * a program does not link to -lthr. Callbacks registered with pthread_atfork()
37  * appear to fail silently. So, it is not always possible to detect a PID
38  * wraparound.
39  */
40 #define _ARC4_ATFORK(f) pthread_atfork(NULL, NULL, (f))
41 
42 static inline void
43 _getentropy_fail(void)
44 {
45 	raise(SIGKILL);
46 }
47 
48 static volatile sig_atomic_t _rs_forked;
49 
50 static inline void
51 _rs_forkhandler(void)
52 {
53 	_rs_forked = 1;
54 }
55 
56 static inline void
57 _rs_forkdetect(void)
58 {
59 	static pid_t _rs_pid = 0;
60 	pid_t pid = getpid();
61 
62 	if (_rs_pid == 0 || _rs_pid != pid || _rs_forked) {
63 		_rs_pid = pid;
64 		_rs_forked = 0;
65 		if (rs)
66 			memset(rs, 0, sizeof(*rs));
67 	}
68 }
69 
70 static inline int
71 _rs_allocate(struct _rs **rsp, struct _rsx **rsxp)
72 {
73 	if ((*rsp = mmap(NULL, sizeof(**rsp), PROT_READ|PROT_WRITE,
74 	    MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED)
75 		return -1;
76 
77 	if ((*rsxp = mmap(NULL, sizeof(**rsxp), PROT_READ|PROT_WRITE,
78 	    MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED) {
79 		munmap(*rsp, sizeof(**rsp));
80 		return -1;
81 	}
82 
83 	_ARC4_ATFORK(_rs_forkhandler);
84 	return 0;
85 }
86