x86/mm: Remove CONFIG_DEBUG_NX_TEST (3ad38ceb) · Commits · 戴 / test

arch/x86/Kconfig.debug

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		@@ -120,14 +120,6 @@ config DEBUG_SET_MODULE_RONX
		against certain classes of kernel exploits.
		If in doubt, say "N".

		config DEBUG_NX_TEST
		tristate "Testcase for the NX non-executable stack feature"
		depends on DEBUG_KERNEL && m
		---help---
		This option enables a testcase for the CPU NX capability
		and the software setup of this feature.
		If in doubt, say "N"

		config DOUBLEFAULT
		default y
		bool "Enable doublefault exception handler" if EXPERT

arch/x86/kernel/Makefile

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Original line number	Diff line number	Diff line
		@@ -101,7 +101,6 @@ obj-$(CONFIG_APB_TIMER) += apb_timer.o

		obj-$(CONFIG_AMD_NB) += amd_nb.o
		obj-$(CONFIG_DEBUG_RODATA_TEST) += test_rodata.o
		obj-$(CONFIG_DEBUG_NX_TEST) += test_nx.o
		obj-$(CONFIG_DEBUG_NMI_SELFTEST) += nmi_selftest.o

		obj-$(CONFIG_KVM_GUEST) += kvm.o kvmclock.o

arch/x86/kernel/test_nx.c

deleted100644 → 0

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Original line number	Diff line number	Diff line
		/*
		* test_nx.c: functional test for NX functionality
		*
		* (C) Copyright 2008 Intel Corporation
		* Author: Arjan van de Ven <arjan@linux.intel.com>
		*
		* This program 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; version 2
		* of the License.
		*/
		#include <linux/module.h>
		#include <linux/sort.h>
		#include <linux/slab.h>

		#include <linux/uaccess.h>
		#include <asm/asm.h>

		extern int rodata_test_data;

		/*
		* This file checks 4 things:
		* 1) Check if the stack is not executable
		* 2) Check if kmalloc memory is not executable
		* 3) Check if the .rodata section is not executable
		* 4) Check if the .data section of a module is not executable
		*
		* To do this, the test code tries to execute memory in stack/kmalloc/etc,
		* and then checks if the expected trap happens.
		*
		* Sadly, this implies having a dynamic exception handling table entry.
		* ... which can be done (and will make Rusty cry)... but it can only
		* be done in a stand-alone module with only 1 entry total.
		* (otherwise we'd have to sort and that's just too messy)
		*/



		/*
		* We want to set up an exception handling point on our stack,
		* which means a variable value. This function is rather dirty
		* and walks the exception table of the module, looking for a magic
		* marker and replaces it with a specific function.
		*/
		static void fudze_exception_table(void marker, void new)
		{
		struct module *mod = THIS_MODULE;
		struct exception_table_entry *extable;

		/*
		* Note: This module has only 1 exception table entry,
		* so searching and sorting is not needed. If that changes,
		* this would be the place to search and re-sort the exception
		* table.
		*/
		if (mod->num_exentries > 1) {
		printk(KERN_ERR "test_nx: too many exception table entries!\n");
		printk(KERN_ERR "test_nx: test results are not reliable.\n");
		return;
		}
		extable = (struct exception_table_entry *)mod->extable;
		extable[0].insn = (unsigned long)new;
		}


		/*
		* exception tables get their symbols translated so we need
		* to use a fake function to put in there, which we can then
		* replace at runtime.
		*/
		void foo_label(void);

		/*
		* returns 0 for not-executable, negative for executable
		*
		* Note: we cannot allow this function to be inlined, because
		* that would give us more than 1 exception table entry.
		* This in turn would break the assumptions above.
		*/
		static noinline int test_address(void *address)
		{
		unsigned long result;

		/* Set up an exception table entry for our address */
		fudze_exception_table(&foo_label, address);
		result = 1;
		asm volatile(
		"foo_label:\n"
		"0: call *%[fake_code]\n"
		"1:\n"
		".section .fixup,\"ax\"\n"
		"2: mov %[zero], %[rslt]\n"
		" ret\n"
		".previous\n"
		_ASM_EXTABLE(0b,2b)
		: [rslt] "=r" (result)
		: [fake_code] "r" (address), [zero] "r" (0UL), "0" (result)
		);
		/* change the exception table back for the next round */
		fudze_exception_table(address, &foo_label);

		if (result)
		return -ENODEV;
		return 0;
		}

		static unsigned char test_data = 0xC3; /* 0xC3 is the opcode for "ret" */

		static int test_NX(void)
		{
		int ret = 0;
		/* 0xC3 is the opcode for "ret" */
		char stackcode[] = {0xC3, 0x90, 0 };
		char *heap;

		test_data = 0xC3;

		printk(KERN_INFO "Testing NX protection\n");

		/* Test 1: check if the stack is not executable */
		if (test_address(&stackcode)) {
		printk(KERN_ERR "test_nx: stack was executable\n");
		ret = -ENODEV;
		}


		/* Test 2: Check if the heap is executable */
		heap = kmalloc(64, GFP_KERNEL);
		if (!heap)
		return -ENOMEM;
		heap[0] = 0xC3; /* opcode for "ret" */

		if (test_address(heap)) {
		printk(KERN_ERR "test_nx: heap was executable\n");
		ret = -ENODEV;
		}
		kfree(heap);

		/*
		* The following 2 tests currently fail, this needs to get fixed
		* Until then, don't run them to avoid too many people getting scared
		* by the error message
		*/

		/* Test 3: Check if the .rodata section is executable */
		if (rodata_test_data != 0xC3) {
		printk(KERN_ERR "test_nx: .rodata marker has invalid value\n");
		ret = -ENODEV;
		} else if (test_address(&rodata_test_data)) {
		printk(KERN_ERR "test_nx: .rodata section is executable\n");
		ret = -ENODEV;
		}

		#if 0
		/* Test 4: Check if the .data section of a module is executable */
		if (test_address(&test_data)) {
		printk(KERN_ERR "test_nx: .data section is executable\n");
		ret = -ENODEV;
		}

		#endif
		return ret;
		}

		static void test_exit(void)
		{
		}

		module_init(test_NX);
		module_exit(test_exit);
		MODULE_LICENSE("GPL");
		MODULE_DESCRIPTION("Testcase for the NX infrastructure");
		MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>");

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