nptl/tst-stackguard1.c

   1 /* Copyright (C) 2005-2016 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 <stackguard-macros.h>
  27 #include <tls.h>
  28 #include <unistd.h>
  29
  30 static const char *command;
  31 static bool child;
  32 static uintptr_t stack_chk_guard_copy;
  33 static bool stack_chk_guard_copy_set;
  34 static int fds[2];
  35
  36 static void __attribute__ ((constructor))
  37 con (void)
  38 {
  39   stack_chk_guard_copy = STACK_CHK_GUARD;
  40   stack_chk_guard_copy_set = true;
  41 }
  42
  43 static int
  44 uintptr_t_cmp (const void *a, const void *b)
  45 {
  46   if (*(uintptr_t *) a < *(uintptr_t *) b)
  47     return 1;
  48   if (*(uintptr_t *) a > *(uintptr_t *) b)
  49     return -1;
  50   return 0;
  51 }
  52
  53 static void *
  54 tf (void *arg)
  55 {
  56   if (stack_chk_guard_copy != STACK_CHK_GUARD)
  57     {
  58       puts ("STACK_CHK_GUARD changed in thread");
  59       return (void *) 1L;
  60     }
  61   return NULL;
  62 }
  63
  64 static int
  65 do_test (void)
  66 {
  67   if (!stack_chk_guard_copy_set)
  68     {
  69       puts ("constructor has not been run");
  70       return 1;
  71     }
  72
  73   if (stack_chk_guard_copy != STACK_CHK_GUARD)
  74     {
  75       puts ("STACK_CHK_GUARD changed between constructor and do_test");
  76       return 1;
  77     }
  78
  79   if (child)
  80     {
  81       int i;
  82       pthread_t th[4];
  83       void *ret;
  84       for (i = 0; i < 4; ++i)
  85         if (pthread_create (&th[i], NULL, tf, NULL))
  86           {
  87             puts ("thread creation failed");
  88             return 1;
  89           }
  90       for (i = 0; i < 4; ++i)
  91         if (pthread_join (th[i], &ret))
  92           {
  93             puts ("thread join failed");
  94             return 1;
  95           }
  96         else if (ret != NULL)
  97           return 1;
  98
  99       write (2, &stack_chk_guard_copy, sizeof (stack_chk_guard_copy));
 100       return 0;
 101     }
 102
 103   if (command == NULL)
 104     {
 105       puts ("missing --command or --child argument");
 106       return 1;
 107     }
 108
 109 #define N 16
 110   uintptr_t child_stack_chk_guards[N + 1];
 111   child_stack_chk_guards[N] = stack_chk_guard_copy;
 112   int i;
 113   for (i = 0; i < N; ++i)
 114     {
 115       if (pipe (fds) < 0)
 116         {
 117           printf ("couldn't create pipe: %m\n");
 118           return 1;
 119         }
 120
 121       pid_t pid = fork ();
 122       if (pid < 0)
 123         {
 124           printf ("fork failed: %m\n");
 125           return 1;
 126         }
 127
 128       if (!pid)
 129         {
 130           if (stack_chk_guard_copy != STACK_CHK_GUARD)
 131             {
 132               puts ("STACK_CHK_GUARD changed after fork");
 133               exit (1);
 134             }
 135
 136           close (fds[0]);
 137           close (2);
 138           dup2 (fds[1], 2);
 139           close (fds[1]);
 140
 141           system (command);
 142           exit (0);
 143         }
 144
 145       close (fds[1]);
 146
 147       if (TEMP_FAILURE_RETRY (read (fds[0], &child_stack_chk_guards[i],
 148                                     sizeof (uintptr_t))) != sizeof (uintptr_t))
 149         {
 150           puts ("could not read stack_chk_guard value from child");
 151           return 1;
 152         }
 153
 154       close (fds[0]);
 155
 156       pid_t termpid;
 157       int status;
 158       termpid = TEMP_FAILURE_RETRY (waitpid (pid, &status, 0));
 159       if (termpid == -1)
 160         {
 161           printf ("waitpid failed: %m\n");
 162           return 1;
 163         }
 164       else if (termpid != pid)
 165         {
 166           printf ("waitpid returned %ld != %ld\n",
 167                   (long int) termpid, (long int) pid);
 168           return 1;
 169         }
 170       else if (!WIFEXITED (status) || WEXITSTATUS (status))
 171         {
 172           puts ("child hasn't exited with exit status 0");
 173           return 1;
 174         }
 175     }
 176
 177   qsort (child_stack_chk_guards, N + 1, sizeof (uintptr_t), uintptr_t_cmp);
 178
 179   uintptr_t default_guard = 0;
 180   unsigned char *p = (unsigned char *) &default_guard;
 181   p[sizeof (uintptr_t) - 1] = 255;
 182   p[sizeof (uintptr_t) - 2] = '\n';
 183   p[0] = 0;
 184
 185   /* Test if the stack guard canaries are either randomized,
 186      or equal to the default stack guard canary value.
 187      Even with randomized stack guards it might happen
 188      that the random number generator generates the same
 189      values, but if that happens in more than half from
 190      the 16 runs, something is very wrong.  */
 191   int ndifferences = 0;
 192   int ndefaults = 0;
 193   for (i = 0; i < N; ++i)
 194     {
 195       if (child_stack_chk_guards[i] != child_stack_chk_guards[i+1])
 196         ndifferences++;
 197       else if (child_stack_chk_guards[i] == default_guard)
 198         ndefaults++;
 199     }
 200
 201   printf ("differences %d defaults %d\n", ndifferences, ndefaults);
 202
 203   if (ndifferences < N / 2 && ndefaults < N / 2)
 204     {
 205       puts ("stack guard canaries are not randomized enough");
 206       puts ("nor equal to the default canary value");
 207       return 1;
 208     }
 209
 210   return 0;
 211 }
 212
 213 #define OPT_COMMAND     10000
 214 #define OPT_CHILD       10001
 215 #define CMDLINE_OPTIONS \
 216   { "command", required_argument, NULL, OPT_COMMAND },  \
 217   { "child", no_argument, NULL, OPT_CHILD },
 218 #define CMDLINE_PROCESS \
 219   case OPT_COMMAND:     \
 220     command = optarg;   \
 221     break;              \
 222   case OPT_CHILD:       \
 223     child = true;       \
 224     break;
 225 #define TEST_FUNCTION do_test ()
 226 #include "../test-skeleton.c"