1/*	$OpenBSD: arc4random_linux.h,v 1.7 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#include "private/bionic_prctl.h"
31
32// Android gets these from "thread_private.h".
33#include "thread_private.h"
34//static pthread_mutex_t arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;
35//#define _ARC4_LOCK()   pthread_mutex_lock(&arc4random_mtx)
36//#define _ARC4_UNLOCK() pthread_mutex_unlock(&arc4random_mtx)
37
38#ifdef __GLIBC__
39extern void *__dso_handle;
40extern int __register_atfork(void (*)(void), void(*)(void), void (*)(void), void *);
41#define _ARC4_ATFORK(f) __register_atfork(NULL, NULL, (f), __dso_handle)
42#else
43#define _ARC4_ATFORK(f) pthread_atfork(NULL, NULL, (f))
44#endif
45
46static inline void
47_getentropy_fail(void)
48{
49	raise(SIGKILL);
50}
51
52static volatile sig_atomic_t _rs_forked;
53
54static inline void
55_rs_forkhandler(void)
56{
57	_rs_forked = 1;
58}
59
60static inline void
61_rs_forkdetect(void)
62{
63	static pid_t _rs_pid = 0;
64	pid_t pid = getpid();
65
66	if (_rs_pid == 0 || _rs_pid != pid || _rs_forked) {
67		_rs_pid = pid;
68		_rs_forked = 0;
69		if (rs)
70			memset(rs, 0, sizeof(*rs));
71	}
72}
73
74static inline int
75_rs_allocate(struct _rs **rsp, struct _rsx **rsxp)
76{
77	if ((*rsp = mmap(NULL, sizeof(**rsp), PROT_READ|PROT_WRITE,
78	    MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED)
79		return (-1);
80
81	prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, *rsp, sizeof(**rsp),
82	    "arc4random _rs structure");
83
84	if ((*rsxp = mmap(NULL, sizeof(**rsxp), PROT_READ|PROT_WRITE,
85	    MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED) {
86		munmap(*rsxp, sizeof(**rsxp));
87		return (-1);
88	}
89
90	prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, *rsxp, sizeof(**rsxp),
91	    "arc4random _rsx structure");
92
93	_ARC4_ATFORK(_rs_forkhandler);
94	return (0);
95}
96