sysdeps/unix/sysv/linux/dl-execstack.c

   1 /* Stack executability handling for GNU dynamic linker.  Linux version.
   2    Copyright (C) 2003-2025 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, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <ldsodefs.h>
  20
  21 int
  22 _dl_make_stack_executable (const void *stack_endp)
  23 {
  24   /* This gives us the highest/lowest page that needs to be changed.  */
  25   uintptr_t page = ((uintptr_t) stack_endp
  26                     & -(intptr_t) GLRO(dl_pagesize));
  27
  28   if (__mprotect ((void *) page, GLRO(dl_pagesize),
  29                   PROT_READ | PROT_WRITE | PROT_EXEC
  30 #if _STACK_GROWS_DOWN
  31                   | PROT_GROWSDOWN
  32 #elif _STACK_GROWS_UP
  33                   | PROT_GROWSUP
  34 #endif
  35                   ) != 0)
  36     return errno;
  37
  38   /* Remember that we changed the permission.  */
  39   GL(dl_stack_flags) |= PF_X;
  40
  41   return 0;
  42 }