lua-arc4random

Cryptographically secure PRNG for Lua
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arc4random_freebsd.h (2386B)

      1 /*	$OpenBSD: arc4random_freebsd.h,v 1.1 2014/07/20 20:51:13 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 }