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.
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 #if defined(__GLIBC__) && !(defined(__UCLIBC__) && !defined(__ARCH_USE_MMU__))
36 extern void *__dso_handle;
37 extern int __register_atfork(void (*)(void), void(*)(void), void (*)(void), void *);
38 #define _ARC4_ATFORK(f) __register_atfork(NULL, NULL, (f), __dso_handle)
39 #else
40 #define _ARC4_ATFORK(f) pthread_atfork(NULL, NULL, (f))
41 #endif
42
43 static inline void
_getentropy_fail(void)44 _getentropy_fail(void)
45 {
46 raise(SIGKILL);
47 }
48
49 static volatile sig_atomic_t _rs_forked;
50
51 static inline void
_rs_forkhandler(void)52 _rs_forkhandler(void)
53 {
54 _rs_forked = 1;
55 }
56
57 static inline void
_rs_forkdetect(void)58 _rs_forkdetect(void)
59 {
60 static pid_t _rs_pid = 0;
61 pid_t pid = getpid();
62
63 /* XXX unusual calls to clone() can bypass checks */
64 if (_rs_pid == 0 || _rs_pid == 1 || _rs_pid != pid || _rs_forked) {
65 _rs_pid = pid;
66 _rs_forked = 0;
67 if (rs)
68 memset(rs, 0, sizeof(*rs));
69 }
70 }
71
72 static inline int
_rs_allocate(struct _rs ** rsp,struct _rsx ** rsxp)73 _rs_allocate(struct _rs **rsp, struct _rsx **rsxp)
74 {
75 if ((*rsp = mmap(NULL, sizeof(**rsp), PROT_READ|PROT_WRITE,
76 MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED)
77 return (-1);
78
79 if ((*rsxp = mmap(NULL, sizeof(**rsxp), PROT_READ|PROT_WRITE,
80 MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED) {
81 munmap(*rsp, sizeof(**rsp));
82 *rsp = NULL;
83 return (-1);
84 }
85
86 _ARC4_ATFORK(_rs_forkhandler);
87 return (0);
88 }
89