nptl/tst-stackguard1.c

   1 /* Copyright (C) 2005-2020 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    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <pthread.h>
  21 #include <stdbool.h>
  22 #include <stddef.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <sys/wait.h>
  27 #include <stackguard-macros.h>
  28 #include <tls.h>
  29 #include <unistd.h>
  30
  31 static const char *command;
  32 static bool child;
  33 static uintptr_t stack_chk_guard_copy;
  34 static bool stack_chk_guard_copy_set;
  35 static int fds[2];
  36
  37 static void __attribute__ ((constructor))
  38 con (void)
  39 {
  40   stack_chk_guard_copy = STACK_CHK_GUARD;
  41   stack_chk_guard_copy_set = true;
  42 }
  43
  44 static int
  45 uintptr_t_cmp (const void *a, const void *b)
  46 {
  47   if (*(uintptr_t *) a < *(uintptr_t *) b)
  48     return 1;
  49   if (*(uintptr_t *) a > *(uintptr_t *) b)
  50     return -1;
  51   return 0;
  52 }
  53
  54 static void *
  55 tf (void *arg)
  56 {
  57   if (stack_chk_guard_copy != STACK_CHK_GUARD)
  58     {
  59       puts ("STACK_CHK_GUARD changed in thread");
  60       return (void *) 1L;
  61     }
  62   return NULL;
  63 }
  64
  65 static int
  66 do_test (void)
  67 {
  68   if (!stack_chk_guard_copy_set)
  69     {
  70       puts ("constructor has not been run");
  71       return 1;
  72     }
  73
  74   if (stack_chk_guard_copy != STACK_CHK_GUARD)
  75     {
  76       puts ("STACK_CHK_GUARD changed between constructor and do_test");
  77       return 1;
  78     }
  79
  80   if (child)
  81     {
  82       int i;
  83       pthread_t th[4];
  84       void *ret;
  85       for (i = 0; i < 4; ++i)
  86         if (pthread_create (&th[i], NULL, tf, NULL))
  87           {
  88             puts ("thread creation failed");
  89             return 1;
  90           }
  91       for (i = 0; i < 4; ++i)
  92         if (pthread_join (th[i], &ret))
  93           {
  94             puts ("thread join failed");
  95             return 1;
  96           }
  97         else if (ret != NULL)
  98           return 1;
  99
 100       write (2, &stack_chk_guard_copy, sizeof (stack_chk_guard_copy));
 101       return 0;
 102     }
 103
 104   if (command == NULL)
 105     {
 106       puts ("missing --command or --child argument");
 107       return 1;
 108     }
 109
 110 #define N 16
 111   uintptr_t child_stack_chk_guards[N + 1];
 112   child_stack_chk_guards[N] = stack_chk_guard_copy;
 113   int i;
 114   for (i = 0; i < N; ++i)
 115     {
 116       if (pipe (fds) < 0)
 117         {
 118           printf ("couldn't create pipe: %m\n");
 119           return 1;
 120         }
 121
 122       pid_t pid = fork ();
 123       if (pid < 0)
 124         {
 125           printf ("fork failed: %m\n");
 126           return 1;
 127         }
 128
 129       if (!pid)
 130         {
 131           if (stack_chk_guard_copy != STACK_CHK_GUARD)
 132             {
 133               puts ("STACK_CHK_GUARD changed after fork");
 134               exit (1);
 135             }
 136
 137           close (fds[0]);
 138           close (2);
 139           dup2 (fds[1], 2);
 140           close (fds[1]);
 141
 142           system (command);
 143           exit (0);
 144         }
 145
 146       close (fds[1]);
 147
 148       if (TEMP_FAILURE_RETRY (read (fds[0], &child_stack_chk_guards[i],
 149                                     sizeof (uintptr_t))) != sizeof (uintptr_t))
 150         {
 151           puts ("could not read stack_chk_guard value from child");
 152           return 1;
 153         }
 154
 155       close (fds[0]);
 156
 157       pid_t termpid;
 158       int status;
 159       termpid = TEMP_FAILURE_RETRY (waitpid (pid, &status, 0));
 160       if (termpid == -1)
 161         {
 162           printf ("waitpid failed: %m\n");
 163           return 1;
 164         }
 165       else if (termpid != pid)
 166         {
 167           printf ("waitpid returned %ld != %ld\n",
 168                   (long int) termpid, (long int) pid);
 169           return 1;
 170         }
 171       else if (!WIFEXITED (status) || WEXITSTATUS (status))
 172         {
 173           puts ("child hasn't exited with exit status 0");
 174           return 1;
 175         }
 176     }
 177
 178   qsort (child_stack_chk_guards, N + 1, sizeof (uintptr_t), uintptr_t_cmp);
 179
 180   uintptr_t default_guard = 0;
 181   unsigned char *p = (unsigned char *) &default_guard;
 182   p[sizeof (uintptr_t) - 1] = 255;
 183   p[sizeof (uintptr_t) - 2] = '\n';
 184   p[0] = 0;
 185
 186   /* Test if the stack guard canaries are either randomized,
 187      or equal to the default stack guard canary value.
 188      Even with randomized stack guards it might happen
 189      that the random number generator generates the same
 190      values, but if that happens in more than half from
 191      the 16 runs, something is very wrong.  */
 192   int ndifferences = 0;
 193   int ndefaults = 0;
 194   for (i = 0; i < N; ++i)
 195     {
 196       if (child_stack_chk_guards[i] != child_stack_chk_guards[i+1])
 197         ndifferences++;
 198       else if (child_stack_chk_guards[i] == default_guard)
 199         ndefaults++;
 200     }
 201
 202   printf ("differences %d defaults %d\n", ndifferences, ndefaults);
 203
 204   if (ndifferences < N / 2 && ndefaults < N / 2)
 205     {
 206       puts ("stack guard canaries are not randomized enough");
 207       puts ("nor equal to the default canary value");
 208       return 1;
 209     }
 210
 211   return 0;
 212 }
 213
 214 #define OPT_COMMAND     10000
 215 #define OPT_CHILD       10001
 216 #define CMDLINE_OPTIONS \
 217   { "command", required_argument, NULL, OPT_COMMAND },  \
 218   { "child", no_argument, NULL, OPT_CHILD },
 219 #define CMDLINE_PROCESS \
 220   case OPT_COMMAND:     \
 221     command = optarg;   \
 222     break;              \
 223   case OPT_CHILD:       \
 224     child = true;       \
 225     break;
 226 #define TEST_FUNCTION do_test ()
 227 #include "../test-skeleton.c"