sysdeps/mach/hurd/dl-execstack.c

   1 /* Stack executability handling for GNU dynamic linker.  Hurd version.
   2    Copyright (C) 2004 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <ldsodefs.h>
  21 #include <hurdstartup.h>
  22 #include <errno.h>
  23
  24 extern struct hurd_startup_data *_dl_hurd_data attribute_hidden;
  25
  26 /* There is no portable way to know the bounds of the initial thread's stack
  27    so as to mprotect it.  */
  28
  29 int
  30 internal_function
  31 _dl_make_stack_executable (void **stack_endp)
  32 {
  33   /* Challenge the caller.  */
  34   if (__builtin_expect (*stack_endp != __libc_stack_end, 0))
  35     return EPERM;
  36   *stack_endp = NULL;
  37
  38 #ifdef IS_IN_rtld
  39   if (__mprotect ((void *)_dl_hurd_data->stack_base, _dl_hurd_data->stack_size,
  40                   PROT_READ|PROT_WRITE|PROT_EXEC) != 0)
  41     return errno;
  42
  43   /* Remember that we changed the permission.  */
  44   GL(dl_stack_flags) |= PF_X;
  45
  46   return 0;
  47 #else
  48   /* We don't bother to implement this for static linking.  */
  49   return ENOSYS;
  50 #endif
  51 }
  52 rtld_hidden_def (_dl_make_stack_executable)