1  /* Verify that child of the vfork-calling function can't return when
       2     shadow stack is in use.
       3     Copyright (C) 2020-2023 Free Software Foundation, Inc.
       4     This file is part of the GNU C Library.
       5  
       6     The GNU C Library is free software; you can redistribute it and/or
       7     modify it under the terms of the GNU Lesser General Public
       8     License as published by the Free Software Foundation; either
       9     version 2.1 of the License, or (at your option) any later version.
      10  
      11     The GNU C Library is distributed in the hope that it will be useful,
      12     but WITHOUT ANY WARRANTY; without even the implied warranty of
      13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      14     Lesser General Public License for more details.
      15  
      16     You should have received a copy of the GNU Lesser General Public
      17     License along with the GNU C Library; if not, see
      18     <https://www.gnu.org/licenses/>.  */
      19  
      20  #include <stdio.h>
      21  #include <stdlib.h>
      22  #include <unistd.h>
      23  #include <errno.h>
      24  #include <sys/types.h>
      25  #include <sys/wait.h>
      26  #include <x86intrin.h>
      27  #include <support/test-driver.h>
      28  #include <support/xsignal.h>
      29  #include <support/xunistd.h>
      30  
      31  __attribute__ ((noclone, noinline))
      32  static void
      33  do_test_1 (void)
      34  {
      35    pid_t p1;
      36    int fd[2];
      37  
      38    if (pipe (fd) == -1)
      39      {
      40        puts ("pipe failed");
      41        _exit (EXIT_FAILURE);
      42      }
      43  
      44    if ((p1 = vfork ()) == 0)
      45      {
      46        pid_t p = getpid ();
      47        TEMP_FAILURE_RETRY (write (fd[1], &p, sizeof (p)));
      48        /* Child return should trigger SIGSEGV.  */
      49        return;
      50      }
      51    else if (p1 == -1)
      52      {
      53        puts ("vfork failed");
      54        _exit (EXIT_FAILURE);
      55      }
      56  
      57    pid_t p2 = 0;
      58    if (TEMP_FAILURE_RETRY (read (fd[0], &p2, sizeof (pid_t)))
      59        != sizeof (pid_t))
      60      puts ("pipd read failed");
      61    else
      62      {
      63        int r;
      64        if (TEMP_FAILURE_RETRY (waitpid (p1, &r, 0)) != p1)
      65  	puts ("waitpid failed");
      66        else if (r != 0)
      67  	puts ("pip write in child failed");
      68      }
      69  
      70    /* Parent exits immediately so that parent returns without triggering
      71       SIGSEGV when shadow stack isn't in use.  */
      72    _exit (EXIT_FAILURE);
      73  }
      74  
      75  static int
      76  do_test (void)
      77  {
      78    /* NB: This test should trigger SIGSEGV with shadow stack enabled.  */
      79    if (_get_ssp () == 0)
      80      return EXIT_UNSUPPORTED;
      81    do_test_1 ();
      82    /* Child exits immediately so that child returns without triggering
      83       SIGSEGV when shadow stack isn't in use.  */
      84    _exit (EXIT_FAILURE);
      85  }
      86  
      87  #define EXPECTED_SIGNAL (_get_ssp () == 0 ? 0 : SIGSEGV)
      88  #include <support/test-driver.c>