nptl/tst-stackguard1.c

   1 /* Copyright (C) 2005-2024 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <pthread.h>
  20 #include <stdbool.h>
  21 #include <stddef.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 #include <support/xunistd.h>
  31 #include <support/xstdlib.h>
  32
  33 static const char *command;
  34 static bool child;
  35 static uintptr_t stack_chk_guard_copy;
  36 static bool stack_chk_guard_copy_set;
  37 static int fds[2];
  38
  39 static void __attribute__ ((constructor))
  40 con (void)
  41 {
  42   stack_chk_guard_copy = STACK_CHK_GUARD;
  43   stack_chk_guard_copy_set = true;
  44 }
  45
  46 static int
  47 uintptr_t_cmp (const void *a, const void *b)
  48 {
  49   if (*(uintptr_t *) a < *(uintptr_t *) b)
  50     return 1;
  51   if (*(uintptr_t *) a > *(uintptr_t *) b)
  52     return -1;
  53   return 0;
  54 }
  55
  56 static void *
  57 tf (void *arg)
  58 {
  59   if (stack_chk_guard_copy != STACK_CHK_GUARD)
  60     {
  61       puts ("STACK_CHK_GUARD changed in thread");
  62       return (void *) 1L;
  63     }
  64   return NULL;
  65 }
  66
  67 static int
  68 do_test (void)
  69 {
  70   if (!stack_chk_guard_copy_set)
  71     {
  72       puts ("constructor has not been run");
  73       return 1;
  74     }
  75
  76   if (stack_chk_guard_copy != STACK_CHK_GUARD)
  77     {
  78       puts ("STACK_CHK_GUARD changed between constructor and do_test");
  79       return 1;
  80     }
  81
  82   if (child)
  83     {
  84       int i;
  85       pthread_t th[4];
  86       void *ret;
  87       for (i = 0; i < 4; ++i)
  88         if (pthread_create (&th[i], NULL, tf, NULL))
  89           {
  90             puts ("thread creation failed");
  91             return 1;
  92           }
  93       for (i = 0; i < 4; ++i)
  94         if (pthread_join (th[i], &ret))
  95           {
  96             puts ("thread join failed");
  97             return 1;
  98           }
  99         else if (ret != NULL)
 100           return 1;
 101
 102       xwrite (2, &stack_chk_guard_copy, sizeof (stack_chk_guard_copy));
 103       return 0;
 104     }
 105
 106   if (command == NULL)
 107     {
 108       puts ("missing --command or --child argument");
 109       return 1;
 110     }
 111
 112 #define N 16
 113   uintptr_t child_stack_chk_guards[N + 1];
 114   child_stack_chk_guards[N] = stack_chk_guard_copy;
 115   int i;
 116   for (i = 0; i < N; ++i)
 117     {
 118       if (pipe (fds) < 0)
 119         {
 120           printf ("couldn't create pipe: %m\n");
 121           return 1;
 122         }
 123
 124       pid_t pid = fork ();
 125       if (pid < 0)
 126         {
 127           printf ("fork failed: %m\n");
 128           return 1;
 129         }
 130
 131       if (!pid)
 132         {
 133           if (stack_chk_guard_copy != STACK_CHK_GUARD)
 134             {
 135               puts ("STACK_CHK_GUARD changed after fork");
 136               exit (1);
 137             }
 138
 139           close (fds[0]);
 140           close (2);
 141           dup2 (fds[1], 2);
 142           close (fds[1]);
 143
 144           xsystem (command);
 145
 146           exit (0);
 147         }
 148
 149       close (fds[1]);
 150
 151       if (TEMP_FAILURE_RETRY (read (fds[0], &child_stack_chk_guards[i],
 152                                     sizeof (uintptr_t))) != sizeof (uintptr_t))
 153         {
 154           puts ("could not read stack_chk_guard value from child");
 155           return 1;
 156         }
 157
 158       close (fds[0]);
 159
 160       pid_t termpid;
 161       int status;
 162       termpid = TEMP_FAILURE_RETRY (waitpid (pid, &status, 0));
 163       if (termpid == -1)
 164         {
 165           printf ("waitpid failed: %m\n");
 166           return 1;
 167         }
 168       else if (termpid != pid)
 169         {
 170           printf ("waitpid returned %ld != %ld\n",
 171                   (long int) termpid, (long int) pid);
 172           return 1;
 173         }
 174       else if (!WIFEXITED (status) || WEXITSTATUS (status))
 175         {
 176           puts ("child hasn't exited with exit status 0");
 177           return 1;
 178         }
 179     }
 180
 181   qsort (child_stack_chk_guards, N + 1, sizeof (uintptr_t), uintptr_t_cmp);
 182
 183   uintptr_t default_guard = 0;
 184   unsigned char *p = (unsigned char *) &default_guard;
 185   p[sizeof (uintptr_t) - 1] = 255;
 186   p[sizeof (uintptr_t) - 2] = '\n';
 187   p[0] = 0;
 188
 189   /* Test if the stack guard canaries are either randomized,
 190      or equal to the default stack guard canary value.
 191      Even with randomized stack guards it might happen
 192      that the random number generator generates the same
 193      values, but if that happens in more than half from
 194      the 16 runs, something is very wrong.  */
 195   int ndifferences = 0;
 196   int ndefaults = 0;
 197   for (i = 0; i < N; ++i)
 198     {
 199       if (child_stack_chk_guards[i] != child_stack_chk_guards[i+1])
 200         ndifferences++;
 201       else if (child_stack_chk_guards[i] == default_guard)
 202         ndefaults++;
 203     }
 204
 205   printf ("differences %d defaults %d\n", ndifferences, ndefaults);
 206
 207   if (ndifferences < N / 2 && ndefaults < N / 2)
 208     {
 209       puts ("stack guard canaries are not randomized enough");
 210       puts ("nor equal to the default canary value");
 211       return 1;
 212     }
 213
 214   return 0;
 215 }
 216
 217 #define OPT_COMMAND     10000
 218 #define OPT_CHILD       10001
 219 #define CMDLINE_OPTIONS \
 220   { "command", required_argument, NULL, OPT_COMMAND },  \
 221   { "child", no_argument, NULL, OPT_CHILD },
 222 #define CMDLINE_PROCESS \
 223   case OPT_COMMAND:     \
 224     command = optarg;   \
 225     break;              \
 226   case OPT_CHILD:       \
 227     child = true;       \
 228     break;
 229 #define TEST_FUNCTION do_test ()
 230 #include "../test-skeleton.c"