usr/src/test/libc-tests/tests/random/arc4random_forkall.c

   1 /*
   2  * This file and its contents are supplied under the terms of the
   3  * Common Development and Distribution License ("CDDL"), version 1.0.
   4  * You may only use this file in accordance with the terms of version
   5  * 1.0 of the CDDL.
   6  *
   7  * A full copy of the text of the CDDL should have accompanied this
   8  * source.  A copy of the CDDL is also available via the Internet at
   9  * http://www.illumos.org/license/CDDL.
  10  */
  11
  12 /*
  13  * Copyright (c) 2015, Joyent, Inc.
  14  */
  15
  16 /*
  17  * Tests to make sure that a parent and child do not get the same arc4random
  18  * state across a forkall. This source file is used to make two tests. One which
  19  * initializes the data in advance, one of which does not.
  20  */
  21
  22 #include <stdlib.h>
  23 #include <sys/mman.h>
  24 #include <assert.h>
  25 #include <errno.h>
  26 #include <sys/types.h>
  27 #include <unistd.h>
  28 #include <sys/wait.h>
  29
  30 typedef struct arc4_fork {
  31         uint32_t        af_parent;
  32         uint32_t        af_child;
  33         uint8_t         af_pbuf[4096];
  34         uint8_t         af_cbuf[4096];
  35 } arc4_fork_t;
  36
  37 arc4_fork_t *fork_data;
  38
  39 int
  40 main(void)
  41 {
  42         int e, i;
  43         pid_t p, child;
  44
  45 #ifdef  ARC4_PREINIT
  46         (void) arc4random();
  47 #endif
  48
  49         fork_data = (arc4_fork_t *)mmap(NULL, sizeof (arc4_fork_t),
  50             PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);
  51         assert(fork_data != MAP_FAILED);
  52
  53         p = forkall();
  54         assert(p != -1);
  55         if (p == 0) {
  56                 fork_data->af_child = arc4random();
  57                 arc4random_buf(fork_data->af_cbuf, sizeof (fork_data->af_cbuf));
  58                 exit(0);
  59         }
  60
  61         fork_data->af_parent = arc4random();
  62         arc4random_buf(fork_data->af_pbuf, sizeof (fork_data->af_pbuf));
  63         do {
  64                 child = wait(&e);
  65         } while (child == -1 && errno == EINTR);
  66         assert(child == p);
  67
  68         /* Now verify our data doesn't match */
  69         assert(fork_data->af_parent != fork_data->af_child);
  70
  71         /*
  72          * For the buffer here, we're mostly concerned that they aren't somehow
  73          * getting the same stream.
  74          */
  75         for (i = 0; i < sizeof (fork_data->af_pbuf); i++) {
  76                 if (fork_data->af_pbuf[i] != fork_data->af_cbuf[i])
  77                         break;
  78         }
  79         assert(i != sizeof (fork_data->af_pbuf));
  80
  81         return (0);
  82 }