1 /*	$OpenBSD: arc4random_linux.h,v 1.12 2019/07/11 10:37:28 inoguchi 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.  From LibreSSL with some adaptations.
24  */
25 
26 #include <sys/mman.h>
27 
28 #include <signal.h>
29 
30 /* OpenSSH isn't multithreaded */
31 #define _ARC4_LOCK()
32 #define _ARC4_UNLOCK()
33 #define _ARC4_ATFORK(f)
34 
35 static inline void
36 _getentropy_fail(void)
37 {
38 	fatal("getentropy failed");
39 }
40 
41 static volatile sig_atomic_t _rs_forked;
42 
43 static inline void
44 _rs_forkhandler(void)
45 {
46 	_rs_forked = 1;
47 }
48 
49 static inline void
50 _rs_forkdetect(void)
51 {
52 	static pid_t _rs_pid = 0;
53 	pid_t pid = getpid();
54 
55 	if (_rs_pid == 0 || _rs_pid == 1 || _rs_pid != pid || _rs_forked) {
56 		_rs_pid = pid;
57 		_rs_forked = 0;
58 		if (rs)
59 			memset(rs, 0, sizeof(*rs));
60 	}
61 }
62 
63 static inline int
64 _rs_allocate(struct _rs **rsp, struct _rsx **rsxp)
65 {
66 #if defined(MAP_ANON) && defined(MAP_PRIVATE)
67 	if ((*rsp = mmap(NULL, sizeof(**rsp), PROT_READ|PROT_WRITE,
68 	    MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED)
69 		return (-1);
70 
71 	if ((*rsxp = mmap(NULL, sizeof(**rsxp), PROT_READ|PROT_WRITE,
72 	    MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED) {
73 		munmap(*rsp, sizeof(**rsp));
74 		*rsp = NULL;
75 		return (-1);
76 	}
77 #else
78 	if ((*rsp = calloc(1, sizeof(**rsp))) == NULL)
79 		return (-1);
80 	if ((*rsxp = calloc(1, sizeof(**rsxp))) == NULL) {
81 		free(*rsp);
82 		*rsp = NULL;
83 		return (-1);
84 	}
85 #endif
86 
87 	_ARC4_ATFORK(_rs_forkhandler);
88 	return (0);
89 }