Viewing file: enable-execute-stack-mprotect.c (2.36 KB) -rw-r--r-- Select action/file-type: (+) | (+) | (+) | Code (+) | Session (+) | (+) | SDB (+) | (+) | (+) | (+) | (+) | (+) |
/* Implement __enable_execute_stack using mprotect(2). Copyright (C) 2011-2022 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 (); } }
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