| 0,0 → 1,79 |
|---|
| /* Implement __enable_execute_stack using mprotect(2). |
| Copyright (C) 2011-2015 Free Software Foundation, Inc. |
| |
| This file is part of GCC. |
| |
| GCC is free software; you can redistribute it and/or modify it under |
| the terms of the GNU General Public License as published by the Free |
| Software Foundation; either version 3, or (at your option) any later |
| version. |
| |
| GCC is distributed in the hope that it will be useful, but WITHOUT ANY |
| WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| for more details. |
| |
| Under Section 7 of GPL version 3, you are granted additional |
| permissions described in the GCC Runtime Library Exception, version |
| 3.1, as published by the Free Software Foundation. |
| |
| You should have received a copy of the GNU General Public License and |
| a copy of the GCC Runtime Library Exception along with this program; |
| see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <sys/mman.h> |
| #include <unistd.h> |
| #include <stdlib.h> |
| |
| #define STACK_PROT_RWX (PROT_READ | PROT_WRITE | PROT_EXEC) |
| |
| static int need_enable_exec_stack; |
| |
| static void check_enabling (void) __attribute__ ((unused)); |
| extern void __enable_execute_stack (void *); |
| |
| #if defined __sun__ && defined __svr4__ |
| static void __attribute__ ((constructor)) |
| check_enabling (void) |
| { |
| int prot = (int) sysconf (_SC_STACK_PROT); |
| |
| if (prot != STACK_PROT_RWX) |
| need_enable_exec_stack = 1; |
| } |
| #else |
| /* There is no way to query the execute permission of the stack, so |
| we always issue the mprotect() call. */ |
| |
| static int need_enable_exec_stack = 1; |
| #endif |
| |
| /* Attempt to turn on access permissions for the stack. Unfortunately it |
| is not possible to make this namespace-clean.*/ |
| |
| void |
| __enable_execute_stack (void *addr) |
| { |
| if (!need_enable_exec_stack) |
| return; |
| else |
| { |
| static long size, mask; |
| |
| if (size == 0) { |
| size = getpagesize (); |
| mask = ~(size - 1); |
| } |
| |
| char *page = (char *) (((long) addr) & mask); |
| char *end = (char *) |
| ((((long) (addr + __LIBGCC_TRAMPOLINE_SIZE__)) & mask) + size); |
| |
| if (mprotect (page, end - page, STACK_PROT_RWX) < 0) |
| /* Note that no errors should be emitted by this code; it is |
| considered dangerous for library calls to send messages to |
| stdout/stderr. */ |
| abort (); |
| } |
| } |