nptl/tst-stackguard1.c

   1 /* Copyright (C) 2005 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Jakub Jelinek <jakub@redhat.com>, 2005.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <pthread.h>
  21 #include <stdbool.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/wait.h>
  26 #include <elf/stackguard-macros.h>
  27 #include <unistd.h>
  28
  29 static const char *command;
  30 static bool child;
  31 static uintptr_t stack_chk_guard_copy;
  32 static bool stack_chk_guard_copy_set;
  33 static int fds[2];
  34
  35 static void __attribute__ ((constructor))
  36 con (void)
  37 {
  38   stack_chk_guard_copy = STACK_CHK_GUARD;
  39   stack_chk_guard_copy_set = true;
  40 }
  41
  42 static int
  43 uintptr_t_cmp (const void *a, const void *b)
  44 {
  45   if (*(uintptr_t *) a < *(uintptr_t *) b)
  46     return 1;
  47   if (*(uintptr_t *) a > *(uintptr_t *) b)
  48     return -1;
  49   return 0;
  50 }
  51
  52 static void *
  53 tf (void *arg)
  54 {
  55   if (stack_chk_guard_copy != STACK_CHK_GUARD)
  56     {
  57       puts ("STACK_CHK_GUARD changed in thread");
  58       return (void *) 1L;
  59     }
  60   return NULL;
  61 }
  62
  63 static int
  64 do_test (void)
  65 {
  66   if (!stack_chk_guard_copy_set)
  67     {
  68       puts ("constructor has not been run");
  69       return 1;
  70     }
  71
  72   if (stack_chk_guard_copy != STACK_CHK_GUARD)
  73     {
  74       puts ("STACK_CHK_GUARD changed between constructor and do_test");
  75       return 1;
  76     }
  77
  78   if (child)
  79     {
  80       int i;
  81       pthread_t th[4];
  82       void *ret;
  83       for (i = 0; i < 4; ++i)
  84         if (pthread_create (&th[i], NULL, tf, NULL))
  85           {
  86             puts ("thread creation failed");
  87             return 1;
  88           }
  89       for (i = 0; i < 4; ++i)
  90         if (pthread_join (th[i], &ret))
  91           {
  92             puts ("thread join failed");
  93             return 1;
  94           }
  95         else if (ret != NULL)
  96           return 1;
  97
  98       write (2, &stack_chk_guard_copy, sizeof (stack_chk_guard_copy));
  99       return 0;
 100     }
 101
 102   if (command == NULL)
 103     {
 104       puts ("missing --command or --child argument");
 105       return 1;
 106     }
 107
 108 #define N 16
 109   uintptr_t child_stack_chk_guards[N + 1];
 110   child_stack_chk_guards[N] = stack_chk_guard_copy;
 111   int i;
 112   for (i = 0; i < N; ++i)
 113     {
 114       if (pipe (fds) < 0)
 115         {
 116           printf ("couldn't create pipe: %m\n");
 117           return 1;
 118         }
 119
 120       pid_t pid = fork ();
 121       if (pid < 0)
 122         {
 123           printf ("fork failed: %m\n");
 124           return 1;
 125         }
 126
 127       if (!pid)
 128         {
 129           if (stack_chk_guard_copy != STACK_CHK_GUARD)
 130             {
 131               puts ("STACK_CHK_GUARD changed after fork");
 132               exit (1);
 133             }
 134
 135           close (fds[0]);
 136           close (2);
 137           dup2 (fds[1], 2);
 138           close (fds[1]);
 139
 140           system (command);
 141           exit (0);
 142         }
 143
 144       close (fds[1]);
 145
 146       if (TEMP_FAILURE_RETRY (read (fds[0], &child_stack_chk_guards[i],
 147                                     sizeof (uintptr_t))) != sizeof (uintptr_t))
 148         {
 149           puts ("could not read stack_chk_guard value from child");
 150           return 1;
 151         }
 152
 153       close (fds[0]);
 154
 155       pid_t termpid;
 156       int status;
 157       termpid = TEMP_FAILURE_RETRY (waitpid (pid, &status, 0));
 158       if (termpid == -1)
 159         {
 160           printf ("waitpid failed: %m\n");
 161           return 1;
 162         }
 163       else if (termpid != pid)
 164         {
 165           printf ("waitpid returned %ld != %ld\n",
 166                   (long int) termpid, (long int) pid);
 167           return 1;
 168         }
 169       else if (!WIFEXITED (status) || WEXITSTATUS (status))
 170         {
 171           puts ("child hasn't exited with exit status 0");
 172           return 1;
 173         }
 174     }
 175
 176   qsort (child_stack_chk_guards, N + 1, sizeof (uintptr_t), uintptr_t_cmp);
 177
 178   uintptr_t default_guard = 0;
 179   unsigned char *p = (unsigned char *) &default_guard;
 180   p[sizeof (uintptr_t) - 1] = 255;
 181   p[sizeof (uintptr_t) - 2] = '\n';
 182   p[0] = 0;
 183
 184   /* Test if the stack guard canaries are either randomized,
 185      or equal to the default stack guard canary value.
 186      Even with randomized stack guards it might happen
 187      that the random number generator generates the same
 188      values, but if that happens in more than half from
 189      the 16 runs, something is very wrong.  */
 190   int ndifferences = 0;
 191   int ndefaults = 0;
 192   for (i = 0; i < N; ++i)
 193     {
 194       if (child_stack_chk_guards[i] != child_stack_chk_guards[i+1])
 195         ndifferences++;
 196       else if (child_stack_chk_guards[i] == default_guard)
 197         ndefaults++;
 198     }
 199
 200   printf ("differences %d defaults %d\n", ndifferences, ndefaults);
 201
 202   if (ndifferences < N / 2 && ndefaults < N / 2)
 203     {
 204       puts ("stack guard canaries are not randomized enough");
 205       puts ("nor equal to the default canary value");
 206       return 1;
 207     }
 208
 209   return 0;
 210 }
 211
 212 #define OPT_COMMAND     10000
 213 #define OPT_CHILD       10001
 214 #define CMDLINE_OPTIONS \
 215   { "command", required_argument, NULL, OPT_COMMAND },  \
 216   { "child", no_argument, NULL, OPT_CHILD },
 217 #define CMDLINE_PROCESS \
 218   case OPT_COMMAND:     \
 219     command = optarg;   \
 220     break;              \
 221   case OPT_CHILD:       \
 222     child = true;       \
 223     break;
 224 #define TEST_FUNCTION do_test ()
 225 #include "../test-skeleton.c"