elf/tst-stackguard1.c

   1 /* Copyright (C) 2005-2017 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 <getopt.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 int
  54 do_test (void)
  55 {
  56   if (!stack_chk_guard_copy_set)
  57     {
  58       puts ("constructor has not been run");
  59       return 1;
  60     }
  61
  62   if (stack_chk_guard_copy != STACK_CHK_GUARD)
  63     {
  64       puts ("STACK_CHK_GUARD changed between constructor and do_test");
  65       return 1;
  66     }
  67
  68   if (child)
  69     {
  70       write (2, &stack_chk_guard_copy, sizeof (stack_chk_guard_copy));
  71       return 0;
  72     }
  73
  74   if (command == NULL)
  75     {
  76       puts ("missing --command or --child argument");
  77       return 1;
  78     }
  79
  80 #define N 16
  81   uintptr_t child_stack_chk_guards[N + 1];
  82   child_stack_chk_guards[N] = stack_chk_guard_copy;
  83   int i;
  84   for (i = 0; i < N; ++i)
  85     {
  86       if (pipe (fds) < 0)
  87         {
  88           printf ("couldn't create pipe: %m\n");
  89           return 1;
  90         }
  91
  92       pid_t pid = fork ();
  93       if (pid < 0)
  94         {
  95           printf ("fork failed: %m\n");
  96           return 1;
  97         }
  98
  99       if (!pid)
 100         {
 101           if (stack_chk_guard_copy != STACK_CHK_GUARD)
 102             {
 103               puts ("STACK_CHK_GUARD changed after fork");
 104               exit (1);
 105             }
 106
 107           close (fds[0]);
 108           close (2);
 109           dup2 (fds[1], 2);
 110           close (fds[1]);
 111
 112           system (command);
 113           exit (0);
 114         }
 115
 116       close (fds[1]);
 117
 118       if (TEMP_FAILURE_RETRY (read (fds[0], &child_stack_chk_guards[i],
 119                                     sizeof (uintptr_t))) != sizeof (uintptr_t))
 120         {
 121           puts ("could not read stack_chk_guard value from child");
 122           return 1;
 123         }
 124
 125       close (fds[0]);
 126
 127       pid_t termpid;
 128       int status;
 129       termpid = TEMP_FAILURE_RETRY (waitpid (pid, &status, 0));
 130       if (termpid == -1)
 131         {
 132           printf ("waitpid failed: %m\n");
 133           return 1;
 134         }
 135       else if (termpid != pid)
 136         {
 137           printf ("waitpid returned %ld != %ld\n",
 138                   (long int) termpid, (long int) pid);
 139           return 1;
 140         }
 141       else if (!WIFEXITED (status) || WEXITSTATUS (status))
 142         {
 143           puts ("child hasn't exited with exit status 0");
 144           return 1;
 145         }
 146     }
 147
 148   qsort (child_stack_chk_guards, N + 1, sizeof (uintptr_t), uintptr_t_cmp);
 149
 150   uintptr_t default_guard = 0;
 151   unsigned char *p = (unsigned char *) &default_guard;
 152   p[sizeof (uintptr_t) - 1] = 255;
 153   p[sizeof (uintptr_t) - 2] = '\n';
 154   p[0] = 0;
 155
 156   /* Test if the stack guard canaries are either randomized,
 157      or equal to the default stack guard canary value.
 158      Even with randomized stack guards it might happen
 159      that the random number generator generates the same
 160      values, but if that happens in more than half from
 161      the 16 runs, something is very wrong.  */
 162   int ndifferences = 0;
 163   int ndefaults = 0;
 164   for (i = 0; i < N; ++i)
 165     {
 166       if (child_stack_chk_guards[i] != child_stack_chk_guards[i+1])
 167         ndifferences++;
 168       else if (child_stack_chk_guards[i] == default_guard)
 169         ndefaults++;
 170     }
 171
 172   printf ("differences %d defaults %d\n", ndifferences, ndefaults);
 173
 174   if (ndifferences < N / 2 && ndefaults < N / 2)
 175     {
 176       puts ("stack guard canaries are not randomized enough");
 177       puts ("nor equal to the default canary value");
 178       return 1;
 179     }
 180
 181   return 0;
 182 }
 183
 184 #define OPT_COMMAND     10000
 185 #define OPT_CHILD       10001
 186 #define CMDLINE_OPTIONS \
 187   { "command", required_argument, NULL, OPT_COMMAND },  \
 188   { "child", no_argument, NULL, OPT_CHILD },
 189
 190 static void __attribute__((used))
 191 cmdline_process_function (int c)
 192 {
 193   switch (c)
 194     {
 195       case OPT_COMMAND:
 196         command = optarg;
 197         break;
 198       case OPT_CHILD:
 199         child = true;
 200         break;
 201     }
 202 }
 203 #define CMDLINE_PROCESS cmdline_process_function
 204
 205 #include <support/test-driver.c>