exec_prot_support.c revision 296373
1/* $NetBSD: exec_prot_support.c,v 1.1 2011/07/18 23:16:09 jym Exp $ */ 2 3/*- 4 * Copyright (c) 2011 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jean-Yves Migeon. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32#include <sys/cdefs.h> 33__RCSID("$NetBSD: exec_prot_support.c,v 1.1 2011/07/18 23:16:09 jym Exp $"); 34 35#include <stdlib.h> 36#include <sys/sysctl.h> 37 38#include "../../common/exec_prot.h" 39 40/* 41 * Support for executable space protection has always been erratic under i386. 42 * Originally IA-32 can't do per-page execute permission, so it is 43 * implemented using different executable segments for %cs (code segment). 44 * This only allows coarse grained protection, especially when memory starts 45 * being fragmented. 46 * Later, PAE was introduced together with a NX/XD bit in the page table 47 * entry to offer per-page permission. 48 */ 49int 50exec_prot_support(void) 51{ 52 int pae; 53 size_t pae_len = sizeof(pae); 54 55 if (sysctlbyname("machdep.pae", &pae, &pae_len, NULL, 0) == -1) 56 return PARTIAL_XP; 57 58 if (pae == 1) { 59 if (system("cpuctl identify 0 | grep -q NOX") == 0 || 60 system("cpuctl identify 0 | grep -q XD") == 0) 61 return PERPAGE_XP; 62 } 63 64 return PARTIAL_XP; 65} 66