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__
39 extern void *__dso_handle;
40 extern 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
46 static inline void
_getentropy_fail(void)47 _getentropy_fail(void)
48 {
49 raise(SIGKILL);
50 }
51
52 static volatile sig_atomic_t _rs_forked;
53
54 static inline void
_rs_forkhandler(void)55 _rs_forkhandler(void)
56 {
57 _rs_forked = 1;
58 }
59
60 static inline void
_rs_forkdetect(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
74 static inline int
_rs_allocate(struct _rs ** rsp,struct _rsx ** rsxp)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