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 #include "private/libc_logging.h"
32
33 // Android gets these from "thread_private.h".
34 #include "thread_private.h"
35 //static pthread_mutex_t arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;
36 //#define _ARC4_LOCK() pthread_mutex_lock(&arc4random_mtx)
37 //#define _ARC4_UNLOCK() pthread_mutex_unlock(&arc4random_mtx)
38
39 #ifdef __GLIBC__
40 extern void *__dso_handle;
41 extern int __register_atfork(void (*)(void), void(*)(void), void (*)(void), void *);
42 #define _ARC4_ATFORK(f) __register_atfork(NULL, NULL, (f), __dso_handle)
43 #else
44 #define _ARC4_ATFORK(f) pthread_atfork(NULL, NULL, (f))
45 #endif
46
47 static inline void
_getentropy_fail(void)48 _getentropy_fail(void)
49 {
50 __libc_fatal("getentropy failed");
51 }
52
53 volatile sig_atomic_t _rs_forked;
54
55 static inline void
_rs_forkdetect(void)56 _rs_forkdetect(void)
57 {
58 static pid_t _rs_pid = 0;
59 pid_t pid = getpid();
60
61 if (_rs_pid == 0 || _rs_pid != pid || _rs_forked) {
62 _rs_pid = pid;
63 _rs_forked = 0;
64 if (rs)
65 memset(rs, 0, sizeof(*rs));
66 }
67 }
68
69 static inline int
_rs_allocate(struct _rs ** rsp,struct _rsx ** rsxp)70 _rs_allocate(struct _rs **rsp, struct _rsx **rsxp)
71 {
72 // OpenBSD's arc4random_linux.h allocates two separate mappings, but for
73 // themselves they just allocate both structs into one mapping like this.
74 struct {
75 struct _rs rs;
76 struct _rsx rsx;
77 } *p;
78
79 if ((p = mmap(NULL, sizeof(*p), PROT_READ|PROT_WRITE,
80 MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED)
81 return (-1);
82
83 prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, p, sizeof(*p), "arc4random data");
84
85 *rsp = &p->rs;
86 *rsxp = &p->rsx;
87
88 return (0);
89 }
90