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glibc  2.9
dl-execstack.c
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00001 /* Stack executability handling for GNU dynamic linker.  Hurd version.
00002    Copyright (C) 2004 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <ldsodefs.h>
00021 #include <hurdstartup.h>
00022 #include <errno.h>
00023 
00024 extern struct hurd_startup_data *_dl_hurd_data attribute_hidden;
00025 
00026 /* There is no portable way to know the bounds of the initial thread's stack
00027    so as to mprotect it.  */
00028 
00029 int
00030 internal_function
00031 _dl_make_stack_executable (void **stack_endp)
00032 {
00033   /* Challenge the caller.  */
00034   if (__builtin_expect (*stack_endp != __libc_stack_end, 0))
00035     return EPERM;
00036   *stack_endp = NULL;
00037 
00038 #ifdef IS_IN_rtld
00039   if (__mprotect ((void *)_dl_hurd_data->stack_base, _dl_hurd_data->stack_size,
00040                 PROT_READ|PROT_WRITE|PROT_EXEC) != 0)
00041     return errno;
00042 
00043   /* Remember that we changed the permission.  */
00044   GL(dl_stack_flags) |= PF_X;
00045 
00046   return 0;
00047 #else
00048   /* We don't bother to implement this for static linking.  */
00049   return ENOSYS;
00050 #endif
00051 }
00052 rtld_hidden_def (_dl_make_stack_executable)