66 lines
2.5 KiB
C
66 lines
2.5 KiB
C
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/* $NetBSD: exec_prot_support.c,v 1.1 2011/07/18 23:16:09 jym Exp $ */
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/*-
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* Copyright (c) 2011 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Jean-Yves Migeon.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__RCSID("$NetBSD: exec_prot_support.c,v 1.1 2011/07/18 23:16:09 jym Exp $");
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#include <stdlib.h>
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#include <sys/sysctl.h>
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#include "../../common/exec_prot.h"
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/*
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* Support for executable space protection has always been erratic under i386.
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* Originally IA-32 can't do per-page execute permission, so it is
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* implemented using different executable segments for %cs (code segment).
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* This only allows coarse grained protection, especially when memory starts
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* being fragmented.
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* Later, PAE was introduced together with a NX/XD bit in the page table
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* entry to offer per-page permission.
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*/
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int
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exec_prot_support(void)
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{
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int pae;
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size_t pae_len = sizeof(pae);
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if (sysctlbyname("machdep.pae", &pae, &pae_len, NULL, 0) == -1)
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return PARTIAL_XP;
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if (pae == 1) {
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if (system("cpuctl identify 0 | grep -q NOX") == 0 ||
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system("cpuctl identify 0 | grep -q XD") == 0)
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return PERPAGE_XP;
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}
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return PARTIAL_XP;
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}
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