lib/libcrypto/arc4random/arc4random_linux.h

   1 /*      $OpenBSD: arc4random_linux.h,v 1.11 2016/06/30 12:19:51 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  * 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 #ifdef __GLIBC__
  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
  44 _getentropy_fail(void)
  45 {
  46         raise(SIGKILL);
  47 }
  48
  49 static volatile sig_atomic_t _rs_forked;
  50
  51 static inline void
  52 _rs_forkhandler(void)
  53 {
  54         _rs_forked = 1;
  55 }
  56
  57 static 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
  72 static 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 }