1 /*	$OpenBSD: arc4random_freebsd.h,v 1.4 2016/06/30 12:19:51 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  * 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 
26 #include <sys/mman.h>
27 
28 #include <pthread.h>
29 #include <signal.h>
30 
31 static pthread_mutex_t arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;
32 #define _ARC4_LOCK()   pthread_mutex_lock(&arc4random_mtx)
33 #define _ARC4_UNLOCK() pthread_mutex_unlock(&arc4random_mtx)
34 
35 /*
36  * Unfortunately, pthread_atfork() is broken on FreeBSD (at least 9 and 10) if
37  * a program does not link to -lthr. Callbacks registered with pthread_atfork()
38  * appear to fail silently. So, it is not always possible to detect a PID
39  * wraparound.
40  */
41 #define _ARC4_ATFORK(f) pthread_atfork(NULL, NULL, (f))
42 
43 static inline void
44 _getentropy_fail(void)
45 {
46 	raise(SIGKILL);
47 }
48 
49 static volatile sig_atomic_t _rs_forked;
50 
51 static inline void
52 _rs_forkhandler(void)
53 {
54 	_rs_forked = 1;
55 }
56 
57 static inline void
58 _rs_forkdetect(void)
59 {
60 	static pid_t _rs_pid = 0;
61 	pid_t pid = getpid();
62 
63 	if (_rs_pid == 0 || _rs_pid != pid || _rs_forked) {
64 		_rs_pid = pid;
65 		_rs_forked = 0;
66 		if (rs)
67 			memset(rs, 0, sizeof(*rs));
68 	}
69 }
70 
71 static inline int
72 _rs_allocate(struct _rs **rsp, struct _rsx **rsxp)
73 {
74 	if ((*rsp = mmap(NULL, sizeof(**rsp), PROT_READ|PROT_WRITE,
75 	    MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED)
76 		return (-1);
77 
78 	if ((*rsxp = mmap(NULL, sizeof(**rsxp), PROT_READ|PROT_WRITE,
79 	    MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED) {
80 		munmap(*rsp, sizeof(**rsp));
81 		*rsp = NULL;
82 		return (-1);
83 	}
84 
85 	_ARC4_ATFORK(_rs_forkhandler);
86 	return (0);
87 }
88