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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
31static 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__))
36extern void *__dso_handle;
37extern 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
43static inline void
44_getentropy_fail(void)
45{
46 raise(SIGKILL);
47}
48
49static volatile sig_atomic_t _rs_forked;
50
51static inline void
52_rs_forkhandler(void)
53{
54 _rs_forked = 1;
55}
56
57static inline 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
72static inline int
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}