[PATCH 0/5] lkdtm: add usercopy and rodata, fix atomic

[PATCH 0/5] lkdtm: add usercopy and rodata, fix atomic

[Kees Cook]

This adds several new tests to lkdtm.

To test non-executability of .rodata, lkdtm's build method shifted
around a bit requiring a source file rename. But after some objcopy
magic, there is now an architecture-agnostic way to write functions
into .rodata.

The atomic under/overflow test was split so that each case could be
individually tested.

The biggest addition are the usercopy tests (in preparation for
CONFIG_HARDENED_USERCOPY, based on grsecurity/PaX's PAX_USERCOPY).
This tests both directions (copy_to_from, copy_from_user) of the
three error conditions that are checked for: wrong object size,
wrong stack frame, and wrong object markings.

Unless anyone has blocking comments, I'll send a pull to Greg
for this to land in -next soon.

-Kees

[PATCH 1/5] lkdtm: split build into multiple source files

[Kees Cook]

Kbuild lacks a way to do in-place objcopy or other modifications of
built targets, so in order to move functions into non-text sections
without renaming the kernel module, the build of lkdtm must be split
into separate source files. This renames lkdtm.c to lkdtm_core.c in
preparation for adding the source file for the .rodata section.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/misc/Makefile     |    2 +
 drivers/misc/lkdtm.c      | 1023 ---------------------------------------------
 drivers/misc/lkdtm_core.c | 1023 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 1025 insertions(+), 1023 deletions(-)
 delete mode 100644 drivers/misc/lkdtm.c
 create mode 100644 drivers/misc/lkdtm_core.c

diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index b2fb6dbffcef..c3cb6ad8cc37 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -57,3 +57,5 @@ obj-$(CONFIG_ECHO)		+= echo/
 obj-$(CONFIG_VEXPRESS_SYSCFG)	+= vexpress-syscfg.o
 obj-$(CONFIG_CXL_BASE)		+= cxl/
 obj-$(CONFIG_PANEL)             += panel.o
+
+lkdtm-$(CONFIG_LKDTM)		+= lkdtm_core.o
diff --git a/drivers/misc/lkdtm.c b/drivers/misc/lkdtm.c
deleted file mode 100644
index 0a5cbbe12452..000000000000
--- a/drivers/misc/lkdtm.c
+++ /dev/null
@@ -1,1023 +0,0 @@
-/*
- * Kprobe module for testing crash dumps
- *
- * 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; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program 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.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
- *
- * Copyright (C) IBM Corporation, 2006
- *
- * Author: Ankita Garg <ankita@in.ibm.com>
- *
- * This module induces system failures at predefined crashpoints to
- * evaluate the reliability of crash dumps obtained using different dumping
- * solutions.
- *
- * It is adapted from the Linux Kernel Dump Test Tool by
- * Fernando Luis Vazquez Cao <http://lkdtt.sourceforge.net>
- *
- * Debugfs support added by Simon Kagstrom <simon.kagstrom@netinsight.net>
- *
- * See Documentation/fault-injection/provoke-crashes.txt for instructions
- */
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
-#include <linux/kernel.h>
-#include <linux/fs.h>
-#include <linux/module.h>
-#include <linux/buffer_head.h>
-#include <linux/kprobes.h>
-#include <linux/list.h>
-#include <linux/init.h>
-#include <linux/interrupt.h>
-#include <linux/hrtimer.h>
-#include <linux/slab.h>
-#include <scsi/scsi_cmnd.h>
-#include <linux/debugfs.h>
-#include <linux/vmalloc.h>
-#include <linux/mman.h>
-#include <asm/cacheflush.h>
-
-#ifdef CONFIG_IDE
-#include <linux/ide.h>
-#endif
-
-/*
- * Make sure our attempts to over run the kernel stack doesn't trigger
- * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we
- * recurse past the end of THREAD_SIZE by default.
- */
-#if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0)
-#define REC_STACK_SIZE (CONFIG_FRAME_WARN / 2)
-#else
-#define REC_STACK_SIZE (THREAD_SIZE / 8)
-#endif
-#define REC_NUM_DEFAULT ((THREAD_SIZE / REC_STACK_SIZE) * 2)
-
-#define DEFAULT_COUNT 10
-#define EXEC_SIZE 64
-
-enum cname {
-	CN_INVALID,
-	CN_INT_HARDWARE_ENTRY,
-	CN_INT_HW_IRQ_EN,
-	CN_INT_TASKLET_ENTRY,
-	CN_FS_DEVRW,
-	CN_MEM_SWAPOUT,
-	CN_TIMERADD,
-	CN_SCSI_DISPATCH_CMD,
-	CN_IDE_CORE_CP,
-	CN_DIRECT,
-};
-
-enum ctype {
-	CT_NONE,
-	CT_PANIC,
-	CT_BUG,
-	CT_WARNING,
-	CT_EXCEPTION,
-	CT_LOOP,
-	CT_OVERFLOW,
-	CT_CORRUPT_STACK,
-	CT_UNALIGNED_LOAD_STORE_WRITE,
-	CT_OVERWRITE_ALLOCATION,
-	CT_WRITE_AFTER_FREE,
-	CT_READ_AFTER_FREE,
-	CT_WRITE_BUDDY_AFTER_FREE,
-	CT_READ_BUDDY_AFTER_FREE,
-	CT_SOFTLOCKUP,
-	CT_HARDLOCKUP,
-	CT_SPINLOCKUP,
-	CT_HUNG_TASK,
-	CT_EXEC_DATA,
-	CT_EXEC_STACK,
-	CT_EXEC_KMALLOC,
-	CT_EXEC_VMALLOC,
-	CT_EXEC_USERSPACE,
-	CT_ACCESS_USERSPACE,
-	CT_WRITE_RO,
-	CT_WRITE_RO_AFTER_INIT,
-	CT_WRITE_KERN,
-	CT_WRAP_ATOMIC
-};
-
-static char* cp_name[] = {
-	"INT_HARDWARE_ENTRY",
-	"INT_HW_IRQ_EN",
-	"INT_TASKLET_ENTRY",
-	"FS_DEVRW",
-	"MEM_SWAPOUT",
-	"TIMERADD",
-	"SCSI_DISPATCH_CMD",
-	"IDE_CORE_CP",
-	"DIRECT",
-};
-
-static char* cp_type[] = {
-	"PANIC",
-	"BUG",
-	"WARNING",
-	"EXCEPTION",
-	"LOOP",
-	"OVERFLOW",
-	"CORRUPT_STACK",
-	"UNALIGNED_LOAD_STORE_WRITE",
-	"OVERWRITE_ALLOCATION",
-	"WRITE_AFTER_FREE",
-	"READ_AFTER_FREE",
-	"WRITE_BUDDY_AFTER_FREE",
-	"READ_BUDDY_AFTER_FREE",
-	"SOFTLOCKUP",
-	"HARDLOCKUP",
-	"SPINLOCKUP",
-	"HUNG_TASK",
-	"EXEC_DATA",
-	"EXEC_STACK",
-	"EXEC_KMALLOC",
-	"EXEC_VMALLOC",
-	"EXEC_USERSPACE",
-	"ACCESS_USERSPACE",
-	"WRITE_RO",
-	"WRITE_RO_AFTER_INIT",
-	"WRITE_KERN",
-	"WRAP_ATOMIC"
-};
-
-static struct jprobe lkdtm;
-
-static int lkdtm_parse_commandline(void);
-static void lkdtm_handler(void);
-
-static char* cpoint_name;
-static char* cpoint_type;
-static int cpoint_count = DEFAULT_COUNT;
-static int recur_count = REC_NUM_DEFAULT;
-
-static enum cname cpoint = CN_INVALID;
-static enum ctype cptype = CT_NONE;
-static int count = DEFAULT_COUNT;
-static DEFINE_SPINLOCK(count_lock);
-static DEFINE_SPINLOCK(lock_me_up);
-
-static u8 data_area[EXEC_SIZE];
-
-static const unsigned long rodata = 0xAA55AA55;
-static unsigned long ro_after_init __ro_after_init = 0x55AA5500;
-
-module_param(recur_count, int, 0644);
-MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");
-module_param(cpoint_name, charp, 0444);
-MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
-module_param(cpoint_type, charp, 0444);
-MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\
-				"hitting the crash point");
-module_param(cpoint_count, int, 0644);
-MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\
-				"crash point is to be hit to trigger action");
-
-static unsigned int jp_do_irq(unsigned int irq)
-{
-	lkdtm_handler();
-	jprobe_return();
-	return 0;
-}
-
-static irqreturn_t jp_handle_irq_event(unsigned int irq,
-				       struct irqaction *action)
-{
-	lkdtm_handler();
-	jprobe_return();
-	return 0;
-}
-
-static void jp_tasklet_action(struct softirq_action *a)
-{
-	lkdtm_handler();
-	jprobe_return();
-}
-
-static void jp_ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
-{
-	lkdtm_handler();
-	jprobe_return();
-}
-
-struct scan_control;
-
-static unsigned long jp_shrink_inactive_list(unsigned long max_scan,
-					     struct zone *zone,
-					     struct scan_control *sc)
-{
-	lkdtm_handler();
-	jprobe_return();
-	return 0;
-}
-
-static int jp_hrtimer_start(struct hrtimer *timer, ktime_t tim,
-			    const enum hrtimer_mode mode)
-{
-	lkdtm_handler();
-	jprobe_return();
-	return 0;
-}
-
-static int jp_scsi_dispatch_cmd(struct scsi_cmnd *cmd)
-{
-	lkdtm_handler();
-	jprobe_return();
-	return 0;
-}
-
-#ifdef CONFIG_IDE
-static int jp_generic_ide_ioctl(ide_drive_t *drive, struct file *file,
-			struct block_device *bdev, unsigned int cmd,
-			unsigned long arg)
-{
-	lkdtm_handler();
-	jprobe_return();
-	return 0;
-}
-#endif
-
-/* Return the crashpoint number or NONE if the name is invalid */
-static enum ctype parse_cp_type(const char *what, size_t count)
-{
-	int i;
-
-	for (i = 0; i < ARRAY_SIZE(cp_type); i++) {
-		if (!strcmp(what, cp_type[i]))
-			return i + 1;
-	}
-
-	return CT_NONE;
-}
-
-static const char *cp_type_to_str(enum ctype type)
-{
-	if (type == CT_NONE || type < 0 || type > ARRAY_SIZE(cp_type))
-		return "None";
-
-	return cp_type[type - 1];
-}
-
-static const char *cp_name_to_str(enum cname name)
-{
-	if (name == CN_INVALID || name < 0 || name > ARRAY_SIZE(cp_name))
-		return "INVALID";
-
-	return cp_name[name - 1];
-}
-
-
-static int lkdtm_parse_commandline(void)
-{
-	int i;
-	unsigned long flags;
-
-	if (cpoint_count < 1 || recur_count < 1)
-		return -EINVAL;
-
-	spin_lock_irqsave(&count_lock, flags);
-	count = cpoint_count;
-	spin_unlock_irqrestore(&count_lock, flags);
-
-	/* No special parameters */
-	if (!cpoint_type && !cpoint_name)
-		return 0;
-
-	/* Neither or both of these need to be set */
-	if (!cpoint_type || !cpoint_name)
-		return -EINVAL;
-
-	cptype = parse_cp_type(cpoint_type, strlen(cpoint_type));
-	if (cptype == CT_NONE)
-		return -EINVAL;
-
-	for (i = 0; i < ARRAY_SIZE(cp_name); i++) {
-		if (!strcmp(cpoint_name, cp_name[i])) {
-			cpoint = i + 1;
-			return 0;
-		}
-	}
-
-	/* Could not find a valid crash point */
-	return -EINVAL;
-}
-
-static int recursive_loop(int remaining)
-{
-	char buf[REC_STACK_SIZE];
-
-	/* Make sure compiler does not optimize this away. */
-	memset(buf, (remaining & 0xff) | 0x1, REC_STACK_SIZE);
-	if (!remaining)
-		return 0;
-	else
-		return recursive_loop(remaining - 1);
-}
-
-static void do_nothing(void)
-{
-	return;
-}
-
-/* Must immediately follow do_nothing for size calculuations to work out. */
-static void do_overwritten(void)
-{
-	pr_info("do_overwritten wasn't overwritten!\n");
-	return;
-}
-
-static noinline void corrupt_stack(void)
-{
-	/* Use default char array length that triggers stack protection. */
-	char data[8];
-
-	memset((void *)data, 0, 64);
-}
-
-static void noinline execute_location(void *dst)
-{
-	void (*func)(void) = dst;
-
-	pr_info("attempting ok execution at %p\n", do_nothing);
-	do_nothing();
-
-	memcpy(dst, do_nothing, EXEC_SIZE);
-	flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE);
-	pr_info("attempting bad execution at %p\n", func);
-	func();
-}
-
-static void execute_user_location(void *dst)
-{
-	/* Intentionally crossing kernel/user memory boundary. */
-	void (*func)(void) = dst;
-
-	pr_info("attempting ok execution at %p\n", do_nothing);
-	do_nothing();
-
-	if (copy_to_user((void __user *)dst, do_nothing, EXEC_SIZE))
-		return;
-	flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE);
-	pr_info("attempting bad execution at %p\n", func);
-	func();
-}
-
-static void lkdtm_do_action(enum ctype which)
-{
-	switch (which) {
-	case CT_PANIC:
-		panic("dumptest");
-		break;
-	case CT_BUG:
-		BUG();
-		break;
-	case CT_WARNING:
-		WARN_ON(1);
-		break;
-	case CT_EXCEPTION:
-		*((int *) 0) = 0;
-		break;
-	case CT_LOOP:
-		for (;;)
-			;
-		break;
-	case CT_OVERFLOW:
-		(void) recursive_loop(recur_count);
-		break;
-	case CT_CORRUPT_STACK:
-		corrupt_stack();
-		break;
-	case CT_UNALIGNED_LOAD_STORE_WRITE: {
-		static u8 data[5] __attribute__((aligned(4))) = {1, 2,
-				3, 4, 5};
-		u32 *p;
-		u32 val = 0x12345678;
-
-		p = (u32 *)(data + 1);
-		if (*p == 0)
-			val = 0x87654321;
-		*p = val;
-		 break;
-	}
-	case CT_OVERWRITE_ALLOCATION: {
-		size_t len = 1020;
-		u32 *data = kmalloc(len, GFP_KERNEL);
-
-		data[1024 / sizeof(u32)] = 0x12345678;
-		kfree(data);
-		break;
-	}
-	case CT_WRITE_AFTER_FREE: {
-		int *base, *again;
-		size_t len = 1024;
-		/*
-		 * The slub allocator uses the first word to store the free
-		 * pointer in some configurations. Use the middle of the
-		 * allocation to avoid running into the freelist
-		 */
-		size_t offset = (len / sizeof(*base)) / 2;
-
-		base = kmalloc(len, GFP_KERNEL);
-		pr_info("Allocated memory %p-%p\n", base, &base[offset * 2]);
-		pr_info("Attempting bad write to freed memory at %p\n",
-			&base[offset]);
-		kfree(base);
-		base[offset] = 0x0abcdef0;
-		/* Attempt to notice the overwrite. */
-		again = kmalloc(len, GFP_KERNEL);
-		kfree(again);
-		if (again != base)
-			pr_info("Hmm, didn't get the same memory range.\n");
-
-		break;
-	}
-	case CT_READ_AFTER_FREE: {
-		int *base, *val, saw;
-		size_t len = 1024;
-		/*
-		 * The slub allocator uses the first word to store the free
-		 * pointer in some configurations. Use the middle of the
-		 * allocation to avoid running into the freelist
-		 */
-		size_t offset = (len / sizeof(*base)) / 2;
-
-		base = kmalloc(len, GFP_KERNEL);
-		if (!base)
-			break;
-
-		val = kmalloc(len, GFP_KERNEL);
-		if (!val) {
-			kfree(base);
-			break;
-		}
-
-		*val = 0x12345678;
-		base[offset] = *val;
-		pr_info("Value in memory before free: %x\n", base[offset]);
-
-		kfree(base);
-
-		pr_info("Attempting bad read from freed memory\n");
-		saw = base[offset];
-		if (saw != *val) {
-			/* Good! Poisoning happened, so declare a win. */
-			pr_info("Memory correctly poisoned (%x)\n", saw);
-			BUG();
-		}
-		pr_info("Memory was not poisoned\n");
-
-		kfree(val);
-		break;
-	}
-	case CT_WRITE_BUDDY_AFTER_FREE: {
-		unsigned long p = __get_free_page(GFP_KERNEL);
-		if (!p)
-			break;
-		pr_info("Writing to the buddy page before free\n");
-		memset((void *)p, 0x3, PAGE_SIZE);
-		free_page(p);
-		schedule();
-		pr_info("Attempting bad write to the buddy page after free\n");
-		memset((void *)p, 0x78, PAGE_SIZE);
-		/* Attempt to notice the overwrite. */
-		p = __get_free_page(GFP_KERNEL);
-		free_page(p);
-		schedule();
-
-		break;
-	}
-	case CT_READ_BUDDY_AFTER_FREE: {
-		unsigned long p = __get_free_page(GFP_KERNEL);
-		int saw, *val;
-		int *base;
-
-		if (!p)
-			break;
-
-		val = kmalloc(1024, GFP_KERNEL);
-		if (!val) {
-			free_page(p);
-			break;
-		}
-
-		base = (int *)p;
-
-		*val = 0x12345678;
-		base[0] = *val;
-		pr_info("Value in memory before free: %x\n", base[0]);
-		free_page(p);
-		pr_info("Attempting to read from freed memory\n");
-		saw = base[0];
-		if (saw != *val) {
-			/* Good! Poisoning happened, so declare a win. */
-			pr_info("Memory correctly poisoned (%x)\n", saw);
-			BUG();
-		}
-		pr_info("Buddy page was not poisoned\n");
-
-		kfree(val);
-		break;
-	}
-	case CT_SOFTLOCKUP:
-		preempt_disable();
-		for (;;)
-			cpu_relax();
-		break;
-	case CT_HARDLOCKUP:
-		local_irq_disable();
-		for (;;)
-			cpu_relax();
-		break;
-	case CT_SPINLOCKUP:
-		/* Must be called twice to trigger. */
-		spin_lock(&lock_me_up);
-		/* Let sparse know we intended to exit holding the lock. */
-		__release(&lock_me_up);
-		break;
-	case CT_HUNG_TASK:
-		set_current_state(TASK_UNINTERRUPTIBLE);
-		schedule();
-		break;
-	case CT_EXEC_DATA:
-		execute_location(data_area);
-		break;
-	case CT_EXEC_STACK: {
-		u8 stack_area[EXEC_SIZE];
-		execute_location(stack_area);
-		break;
-	}
-	case CT_EXEC_KMALLOC: {
-		u32 *kmalloc_area = kmalloc(EXEC_SIZE, GFP_KERNEL);
-		execute_location(kmalloc_area);
-		kfree(kmalloc_area);
-		break;
-	}
-	case CT_EXEC_VMALLOC: {
-		u32 *vmalloc_area = vmalloc(EXEC_SIZE);
-		execute_location(vmalloc_area);
-		vfree(vmalloc_area);
-		break;
-	}
-	case CT_EXEC_USERSPACE: {
-		unsigned long user_addr;
-
-		user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
-				    PROT_READ | PROT_WRITE | PROT_EXEC,
-				    MAP_ANONYMOUS | MAP_PRIVATE, 0);
-		if (user_addr >= TASK_SIZE) {
-			pr_warn("Failed to allocate user memory\n");
-			return;
-		}
-		execute_user_location((void *)user_addr);
-		vm_munmap(user_addr, PAGE_SIZE);
-		break;
-	}
-	case CT_ACCESS_USERSPACE: {
-		unsigned long user_addr, tmp = 0;
-		unsigned long *ptr;
-
-		user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
-				    PROT_READ | PROT_WRITE | PROT_EXEC,
-				    MAP_ANONYMOUS | MAP_PRIVATE, 0);
-		if (user_addr >= TASK_SIZE) {
-			pr_warn("Failed to allocate user memory\n");
-			return;
-		}
-
-		if (copy_to_user((void __user *)user_addr, &tmp, sizeof(tmp))) {
-			pr_warn("copy_to_user failed\n");
-			vm_munmap(user_addr, PAGE_SIZE);
-			return;
-		}
-
-		ptr = (unsigned long *)user_addr;
-
-		pr_info("attempting bad read at %p\n", ptr);
-		tmp = *ptr;
-		tmp += 0xc0dec0de;
-
-		pr_info("attempting bad write at %p\n", ptr);
-		*ptr = tmp;
-
-		vm_munmap(user_addr, PAGE_SIZE);
-
-		break;
-	}
-	case CT_WRITE_RO: {
-		/* Explicitly cast away "const" for the test. */
-		unsigned long *ptr = (unsigned long *)&rodata;
-
-		pr_info("attempting bad rodata write at %p\n", ptr);
-		*ptr ^= 0xabcd1234;
-
-		break;
-	}
-	case CT_WRITE_RO_AFTER_INIT: {
-		unsigned long *ptr = &ro_after_init;
-
-		/*
-		 * Verify we were written to during init. Since an Oops
-		 * is considered a "success", a failure is to just skip the
-		 * real test.
-		 */
-		if ((*ptr & 0xAA) != 0xAA) {
-			pr_info("%p was NOT written during init!?\n", ptr);
-			break;
-		}
-
-		pr_info("attempting bad ro_after_init write at %p\n", ptr);
-		*ptr ^= 0xabcd1234;
-
-		break;
-	}
-	case CT_WRITE_KERN: {
-		size_t size;
-		unsigned char *ptr;
-
-		size = (unsigned long)do_overwritten -
-		       (unsigned long)do_nothing;
-		ptr = (unsigned char *)do_overwritten;
-
-		pr_info("attempting bad %zu byte write at %p\n", size, ptr);
-		memcpy(ptr, (unsigned char *)do_nothing, size);
-		flush_icache_range((unsigned long)ptr,
-				   (unsigned long)(ptr + size));
-
-		do_overwritten();
-		break;
-	}
-	case CT_WRAP_ATOMIC: {
-		atomic_t under = ATOMIC_INIT(INT_MIN);
-		atomic_t over = ATOMIC_INIT(INT_MAX);
-
-		pr_info("attempting atomic underflow\n");
-		atomic_dec(&under);
-		pr_info("attempting atomic overflow\n");
-		atomic_inc(&over);
-
-		return;
-	}
-	case CT_NONE:
-	default:
-		break;
-	}
-
-}
-
-static void lkdtm_handler(void)
-{
-	unsigned long flags;
-	bool do_it = false;
-
-	spin_lock_irqsave(&count_lock, flags);
-	count--;
-	pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",
-		cp_name_to_str(cpoint), cp_type_to_str(cptype), count);
-
-	if (count == 0) {
-		do_it = true;
-		count = cpoint_count;
-	}
-	spin_unlock_irqrestore(&count_lock, flags);
-
-	if (do_it)
-		lkdtm_do_action(cptype);
-}
-
-static int lkdtm_register_cpoint(enum cname which)
-{
-	int ret;
-
-	cpoint = CN_INVALID;
-	if (lkdtm.entry != NULL)
-		unregister_jprobe(&lkdtm);
-
-	switch (which) {
-	case CN_DIRECT:
-		lkdtm_do_action(cptype);
-		return 0;
-	case CN_INT_HARDWARE_ENTRY:
-		lkdtm.kp.symbol_name = "do_IRQ";
-		lkdtm.entry = (kprobe_opcode_t*) jp_do_irq;
-		break;
-	case CN_INT_HW_IRQ_EN:
-		lkdtm.kp.symbol_name = "handle_IRQ_event";
-		lkdtm.entry = (kprobe_opcode_t*) jp_handle_irq_event;
-		break;
-	case CN_INT_TASKLET_ENTRY:
-		lkdtm.kp.symbol_name = "tasklet_action";
-		lkdtm.entry = (kprobe_opcode_t*) jp_tasklet_action;
-		break;
-	case CN_FS_DEVRW:
-		lkdtm.kp.symbol_name = "ll_rw_block";
-		lkdtm.entry = (kprobe_opcode_t*) jp_ll_rw_block;
-		break;
-	case CN_MEM_SWAPOUT:
-		lkdtm.kp.symbol_name = "shrink_inactive_list";
-		lkdtm.entry = (kprobe_opcode_t*) jp_shrink_inactive_list;
-		break;
-	case CN_TIMERADD:
-		lkdtm.kp.symbol_name = "hrtimer_start";
-		lkdtm.entry = (kprobe_opcode_t*) jp_hrtimer_start;
-		break;
-	case CN_SCSI_DISPATCH_CMD:
-		lkdtm.kp.symbol_name = "scsi_dispatch_cmd";
-		lkdtm.entry = (kprobe_opcode_t*) jp_scsi_dispatch_cmd;
-		break;
-	case CN_IDE_CORE_CP:
-#ifdef CONFIG_IDE
-		lkdtm.kp.symbol_name = "generic_ide_ioctl";
-		lkdtm.entry = (kprobe_opcode_t*) jp_generic_ide_ioctl;
-#else
-		pr_info("Crash point not available\n");
-		return -EINVAL;
-#endif
-		break;
-	default:
-		pr_info("Invalid Crash Point\n");
-		return -EINVAL;
-	}
-
-	cpoint = which;
-	if ((ret = register_jprobe(&lkdtm)) < 0) {
-		pr_info("Couldn't register jprobe\n");
-		cpoint = CN_INVALID;
-	}
-
-	return ret;
-}
-
-static ssize_t do_register_entry(enum cname which, struct file *f,
-		const char __user *user_buf, size_t count, loff_t *off)
-{
-	char *buf;
-	int err;
-
-	if (count >= PAGE_SIZE)
-		return -EINVAL;
-
-	buf = (char *)__get_free_page(GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
-	if (copy_from_user(buf, user_buf, count)) {
-		free_page((unsigned long) buf);
-		return -EFAULT;
-	}
-	/* NULL-terminate and remove enter */
-	buf[count] = '\0';
-	strim(buf);
-
-	cptype = parse_cp_type(buf, count);
-	free_page((unsigned long) buf);
-
-	if (cptype == CT_NONE)
-		return -EINVAL;
-
-	err = lkdtm_register_cpoint(which);
-	if (err < 0)
-		return err;
-
-	*off += count;
-
-	return count;
-}
-
-/* Generic read callback that just prints out the available crash types */
-static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
-		size_t count, loff_t *off)
-{
-	char *buf;
-	int i, n, out;
-
-	buf = (char *)__get_free_page(GFP_KERNEL);
-	if (buf == NULL)
-		return -ENOMEM;
-
-	n = snprintf(buf, PAGE_SIZE, "Available crash types:\n");
-	for (i = 0; i < ARRAY_SIZE(cp_type); i++)
-		n += snprintf(buf + n, PAGE_SIZE - n, "%s\n", cp_type[i]);
-	buf[n] = '\0';
-
-	out = simple_read_from_buffer(user_buf, count, off,
-				      buf, n);
-	free_page((unsigned long) buf);
-
-	return out;
-}
-
-static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
-{
-	return 0;
-}
-
-
-static ssize_t int_hardware_entry(struct file *f, const char __user *buf,
-		size_t count, loff_t *off)
-{
-	return do_register_entry(CN_INT_HARDWARE_ENTRY, f, buf, count, off);
-}
-
-static ssize_t int_hw_irq_en(struct file *f, const char __user *buf,
-		size_t count, loff_t *off)
-{
-	return do_register_entry(CN_INT_HW_IRQ_EN, f, buf, count, off);
-}
-
-static ssize_t int_tasklet_entry(struct file *f, const char __user *buf,
-		size_t count, loff_t *off)
-{
-	return do_register_entry(CN_INT_TASKLET_ENTRY, f, buf, count, off);
-}
-
-static ssize_t fs_devrw_entry(struct file *f, const char __user *buf,
-		size_t count, loff_t *off)
-{
-	return do_register_entry(CN_FS_DEVRW, f, buf, count, off);
-}
-
-static ssize_t mem_swapout_entry(struct file *f, const char __user *buf,
-		size_t count, loff_t *off)
-{
-	return do_register_entry(CN_MEM_SWAPOUT, f, buf, count, off);
-}
-
-static ssize_t timeradd_entry(struct file *f, const char __user *buf,
-		size_t count, loff_t *off)
-{
-	return do_register_entry(CN_TIMERADD, f, buf, count, off);
-}
-
-static ssize_t scsi_dispatch_cmd_entry(struct file *f,
-		const char __user *buf, size_t count, loff_t *off)
-{
-	return do_register_entry(CN_SCSI_DISPATCH_CMD, f, buf, count, off);
-}
-
-static ssize_t ide_core_cp_entry(struct file *f, const char __user *buf,
-		size_t count, loff_t *off)
-{
-	return do_register_entry(CN_IDE_CORE_CP, f, buf, count, off);
-}
-
-/* Special entry to just crash directly. Available without KPROBEs */
-static ssize_t direct_entry(struct file *f, const char __user *user_buf,
-		size_t count, loff_t *off)
-{
-	enum ctype type;
-	char *buf;
-
-	if (count >= PAGE_SIZE)
-		return -EINVAL;
-	if (count < 1)
-		return -EINVAL;
-
-	buf = (char *)__get_free_page(GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
-	if (copy_from_user(buf, user_buf, count)) {
-		free_page((unsigned long) buf);
-		return -EFAULT;
-	}
-	/* NULL-terminate and remove enter */
-	buf[count] = '\0';
-	strim(buf);
-
-	type = parse_cp_type(buf, count);
-	free_page((unsigned long) buf);
-	if (type == CT_NONE)
-		return -EINVAL;
-
-	pr_info("Performing direct entry %s\n", cp_type_to_str(type));
-	lkdtm_do_action(type);
-	*off += count;
-
-	return count;
-}
-
-struct crash_entry {
-	const char *name;
-	const struct file_operations fops;
-};
-
-static const struct crash_entry crash_entries[] = {
-	{"DIRECT", {.read = lkdtm_debugfs_read,
-			.llseek = generic_file_llseek,
-			.open = lkdtm_debugfs_open,
-			.write = direct_entry} },
-	{"INT_HARDWARE_ENTRY", {.read = lkdtm_debugfs_read,
-			.llseek = generic_file_llseek,
-			.open = lkdtm_debugfs_open,
-			.write = int_hardware_entry} },
-	{"INT_HW_IRQ_EN", {.read = lkdtm_debugfs_read,
-			.llseek = generic_file_llseek,
-			.open = lkdtm_debugfs_open,
-			.write = int_hw_irq_en} },
-	{"INT_TASKLET_ENTRY", {.read = lkdtm_debugfs_read,
-			.llseek = generic_file_llseek,
-			.open = lkdtm_debugfs_open,
-			.write = int_tasklet_entry} },
-	{"FS_DEVRW", {.read = lkdtm_debugfs_read,
-			.llseek = generic_file_llseek,
-			.open = lkdtm_debugfs_open,
-			.write = fs_devrw_entry} },
-	{"MEM_SWAPOUT", {.read = lkdtm_debugfs_read,
-			.llseek = generic_file_llseek,
-			.open = lkdtm_debugfs_open,
-			.write = mem_swapout_entry} },
-	{"TIMERADD", {.read = lkdtm_debugfs_read,
-			.llseek = generic_file_llseek,
-			.open = lkdtm_debugfs_open,
-			.write = timeradd_entry} },
-	{"SCSI_DISPATCH_CMD", {.read = lkdtm_debugfs_read,
-			.llseek = generic_file_llseek,
-			.open = lkdtm_debugfs_open,
-			.write = scsi_dispatch_cmd_entry} },
-	{"IDE_CORE_CP",	{.read = lkdtm_debugfs_read,
-			.llseek = generic_file_llseek,
-			.open = lkdtm_debugfs_open,
-			.write = ide_core_cp_entry} },
-};
-
-static struct dentry *lkdtm_debugfs_root;
-
-static int __init lkdtm_module_init(void)
-{
-	int ret = -EINVAL;
-	int n_debugfs_entries = 1; /* Assume only the direct entry */
-	int i;
-
-	/* Make sure we can write to __ro_after_init values during __init */
-	ro_after_init |= 0xAA;
-
-	/* Register debugfs interface */
-	lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
-	if (!lkdtm_debugfs_root) {
-		pr_err("creating root dir failed\n");
-		return -ENODEV;
-	}
-
-#ifdef CONFIG_KPROBES
-	n_debugfs_entries = ARRAY_SIZE(crash_entries);
-#endif
-
-	for (i = 0; i < n_debugfs_entries; i++) {
-		const struct crash_entry *cur = &crash_entries[i];
-		struct dentry *de;
-
-		de = debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root,
-				NULL, &cur->fops);
-		if (de == NULL) {
-			pr_err("could not create %s\n", cur->name);
-			goto out_err;
-		}
-	}
-
-	if (lkdtm_parse_commandline() == -EINVAL) {
-		pr_info("Invalid command\n");
-		goto out_err;
-	}
-
-	if (cpoint != CN_INVALID && cptype != CT_NONE) {
-		ret = lkdtm_register_cpoint(cpoint);
-		if (ret < 0) {
-			pr_info("Invalid crash point %d\n", cpoint);
-			goto out_err;
-		}
-		pr_info("Crash point %s of type %s registered\n",
-			cpoint_name, cpoint_type);
-	} else {
-		pr_info("No crash points registered, enable through debugfs\n");
-	}
-
-	return 0;
-
-out_err:
-	debugfs_remove_recursive(lkdtm_debugfs_root);
-	return ret;
-}
-
-static void __exit lkdtm_module_exit(void)
-{
-	debugfs_remove_recursive(lkdtm_debugfs_root);
-
-	unregister_jprobe(&lkdtm);
-	pr_info("Crash point unregistered\n");
-}
-
-module_init(lkdtm_module_init);
-module_exit(lkdtm_module_exit);
-
-MODULE_LICENSE("GPL");
-MODULE_DESCRIPTION("Kprobe module for testing crash dumps");
diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
new file mode 100644
index 000000000000..0a5cbbe12452
--- /dev/null
+++ b/drivers/misc/lkdtm_core.c
@@ -0,0 +1,1023 @@
+/*
+ * Kprobe module for testing crash dumps
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2006
+ *
+ * Author: Ankita Garg <ankita@in.ibm.com>
+ *
+ * This module induces system failures at predefined crashpoints to
+ * evaluate the reliability of crash dumps obtained using different dumping
+ * solutions.
+ *
+ * It is adapted from the Linux Kernel Dump Test Tool by
+ * Fernando Luis Vazquez Cao <http://lkdtt.sourceforge.net>
+ *
+ * Debugfs support added by Simon Kagstrom <simon.kagstrom@netinsight.net>
+ *
+ * See Documentation/fault-injection/provoke-crashes.txt for instructions
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/buffer_head.h>
+#include <linux/kprobes.h>
+#include <linux/list.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/hrtimer.h>
+#include <linux/slab.h>
+#include <scsi/scsi_cmnd.h>
+#include <linux/debugfs.h>
+#include <linux/vmalloc.h>
+#include <linux/mman.h>
+#include <asm/cacheflush.h>
+
+#ifdef CONFIG_IDE
+#include <linux/ide.h>
+#endif
+
+/*
+ * Make sure our attempts to over run the kernel stack doesn't trigger
+ * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we
+ * recurse past the end of THREAD_SIZE by default.
+ */
+#if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0)
+#define REC_STACK_SIZE (CONFIG_FRAME_WARN / 2)
+#else
+#define REC_STACK_SIZE (THREAD_SIZE / 8)
+#endif
+#define REC_NUM_DEFAULT ((THREAD_SIZE / REC_STACK_SIZE) * 2)
+
+#define DEFAULT_COUNT 10
+#define EXEC_SIZE 64
+
+enum cname {
+	CN_INVALID,
+	CN_INT_HARDWARE_ENTRY,
+	CN_INT_HW_IRQ_EN,
+	CN_INT_TASKLET_ENTRY,
+	CN_FS_DEVRW,
+	CN_MEM_SWAPOUT,
+	CN_TIMERADD,
+	CN_SCSI_DISPATCH_CMD,
+	CN_IDE_CORE_CP,
+	CN_DIRECT,
+};
+
+enum ctype {
+	CT_NONE,
+	CT_PANIC,
+	CT_BUG,
+	CT_WARNING,
+	CT_EXCEPTION,
+	CT_LOOP,
+	CT_OVERFLOW,
+	CT_CORRUPT_STACK,
+	CT_UNALIGNED_LOAD_STORE_WRITE,
+	CT_OVERWRITE_ALLOCATION,
+	CT_WRITE_AFTER_FREE,
+	CT_READ_AFTER_FREE,
+	CT_WRITE_BUDDY_AFTER_FREE,
+	CT_READ_BUDDY_AFTER_FREE,
+	CT_SOFTLOCKUP,
+	CT_HARDLOCKUP,
+	CT_SPINLOCKUP,
+	CT_HUNG_TASK,
+	CT_EXEC_DATA,
+	CT_EXEC_STACK,
+	CT_EXEC_KMALLOC,
+	CT_EXEC_VMALLOC,
+	CT_EXEC_USERSPACE,
+	CT_ACCESS_USERSPACE,
+	CT_WRITE_RO,
+	CT_WRITE_RO_AFTER_INIT,
+	CT_WRITE_KERN,
+	CT_WRAP_ATOMIC
+};
+
+static char* cp_name[] = {
+	"INT_HARDWARE_ENTRY",
+	"INT_HW_IRQ_EN",
+	"INT_TASKLET_ENTRY",
+	"FS_DEVRW",
+	"MEM_SWAPOUT",
+	"TIMERADD",
+	"SCSI_DISPATCH_CMD",
+	"IDE_CORE_CP",
+	"DIRECT",
+};
+
+static char* cp_type[] = {
+	"PANIC",
+	"BUG",
+	"WARNING",
+	"EXCEPTION",
+	"LOOP",
+	"OVERFLOW",
+	"CORRUPT_STACK",
+	"UNALIGNED_LOAD_STORE_WRITE",
+	"OVERWRITE_ALLOCATION",
+	"WRITE_AFTER_FREE",
+	"READ_AFTER_FREE",
+	"WRITE_BUDDY_AFTER_FREE",
+	"READ_BUDDY_AFTER_FREE",
+	"SOFTLOCKUP",
+	"HARDLOCKUP",
+	"SPINLOCKUP",
+	"HUNG_TASK",
+	"EXEC_DATA",
+	"EXEC_STACK",
+	"EXEC_KMALLOC",
+	"EXEC_VMALLOC",
+	"EXEC_USERSPACE",
+	"ACCESS_USERSPACE",
+	"WRITE_RO",
+	"WRITE_RO_AFTER_INIT",
+	"WRITE_KERN",
+	"WRAP_ATOMIC"
+};
+
+static struct jprobe lkdtm;
+
+static int lkdtm_parse_commandline(void);
+static void lkdtm_handler(void);
+
+static char* cpoint_name;
+static char* cpoint_type;
+static int cpoint_count = DEFAULT_COUNT;
+static int recur_count = REC_NUM_DEFAULT;
+
+static enum cname cpoint = CN_INVALID;
+static enum ctype cptype = CT_NONE;
+static int count = DEFAULT_COUNT;
+static DEFINE_SPINLOCK(count_lock);
+static DEFINE_SPINLOCK(lock_me_up);
+
+static u8 data_area[EXEC_SIZE];
+
+static const unsigned long rodata = 0xAA55AA55;
+static unsigned long ro_after_init __ro_after_init = 0x55AA5500;
+
+module_param(recur_count, int, 0644);
+MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");
+module_param(cpoint_name, charp, 0444);
+MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
+module_param(cpoint_type, charp, 0444);
+MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\
+				"hitting the crash point");
+module_param(cpoint_count, int, 0644);
+MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\
+				"crash point is to be hit to trigger action");
+
+static unsigned int jp_do_irq(unsigned int irq)
+{
+	lkdtm_handler();
+	jprobe_return();
+	return 0;
+}
+
+static irqreturn_t jp_handle_irq_event(unsigned int irq,
+				       struct irqaction *action)
+{
+	lkdtm_handler();
+	jprobe_return();
+	return 0;
+}
+
+static void jp_tasklet_action(struct softirq_action *a)
+{
+	lkdtm_handler();
+	jprobe_return();
+}
+
+static void jp_ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
+{
+	lkdtm_handler();
+	jprobe_return();
+}
+
+struct scan_control;
+
+static unsigned long jp_shrink_inactive_list(unsigned long max_scan,
+					     struct zone *zone,
+					     struct scan_control *sc)
+{
+	lkdtm_handler();
+	jprobe_return();
+	return 0;
+}
+
+static int jp_hrtimer_start(struct hrtimer *timer, ktime_t tim,
+			    const enum hrtimer_mode mode)
+{
+	lkdtm_handler();
+	jprobe_return();
+	return 0;
+}
+
+static int jp_scsi_dispatch_cmd(struct scsi_cmnd *cmd)
+{
+	lkdtm_handler();
+	jprobe_return();
+	return 0;
+}
+
+#ifdef CONFIG_IDE
+static int jp_generic_ide_ioctl(ide_drive_t *drive, struct file *file,
+			struct block_device *bdev, unsigned int cmd,
+			unsigned long arg)
+{
+	lkdtm_handler();
+	jprobe_return();
+	return 0;
+}
+#endif
+
+/* Return the crashpoint number or NONE if the name is invalid */
+static enum ctype parse_cp_type(const char *what, size_t count)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(cp_type); i++) {
+		if (!strcmp(what, cp_type[i]))
+			return i + 1;
+	}
+
+	return CT_NONE;
+}
+
+static const char *cp_type_to_str(enum ctype type)
+{
+	if (type == CT_NONE || type < 0 || type > ARRAY_SIZE(cp_type))
+		return "None";
+
+	return cp_type[type - 1];
+}
+
+static const char *cp_name_to_str(enum cname name)
+{
+	if (name == CN_INVALID || name < 0 || name > ARRAY_SIZE(cp_name))
+		return "INVALID";
+
+	return cp_name[name - 1];
+}
+
+
+static int lkdtm_parse_commandline(void)
+{
+	int i;
+	unsigned long flags;
+
+	if (cpoint_count < 1 || recur_count < 1)
+		return -EINVAL;
+
+	spin_lock_irqsave(&count_lock, flags);
+	count = cpoint_count;
+	spin_unlock_irqrestore(&count_lock, flags);
+
+	/* No special parameters */
+	if (!cpoint_type && !cpoint_name)
+		return 0;
+
+	/* Neither or both of these need to be set */
+	if (!cpoint_type || !cpoint_name)
+		return -EINVAL;
+
+	cptype = parse_cp_type(cpoint_type, strlen(cpoint_type));
+	if (cptype == CT_NONE)
+		return -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(cp_name); i++) {
+		if (!strcmp(cpoint_name, cp_name[i])) {
+			cpoint = i + 1;
+			return 0;
+		}
+	}
+
+	/* Could not find a valid crash point */
+	return -EINVAL;
+}
+
+static int recursive_loop(int remaining)
+{
+	char buf[REC_STACK_SIZE];
+
+	/* Make sure compiler does not optimize this away. */
+	memset(buf, (remaining & 0xff) | 0x1, REC_STACK_SIZE);
+	if (!remaining)
+		return 0;
+	else
+		return recursive_loop(remaining - 1);
+}
+
+static void do_nothing(void)
+{
+	return;
+}
+
+/* Must immediately follow do_nothing for size calculuations to work out. */
+static void do_overwritten(void)
+{
+	pr_info("do_overwritten wasn't overwritten!\n");
+	return;
+}
+
+static noinline void corrupt_stack(void)
+{
+	/* Use default char array length that triggers stack protection. */
+	char data[8];
+
+	memset((void *)data, 0, 64);
+}
+
+static void noinline execute_location(void *dst)
+{
+	void (*func)(void) = dst;
+
+	pr_info("attempting ok execution at %p\n", do_nothing);
+	do_nothing();
+
+	memcpy(dst, do_nothing, EXEC_SIZE);
+	flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE);
+	pr_info("attempting bad execution at %p\n", func);
+	func();
+}
+
+static void execute_user_location(void *dst)
+{
+	/* Intentionally crossing kernel/user memory boundary. */
+	void (*func)(void) = dst;
+
+	pr_info("attempting ok execution at %p\n", do_nothing);
+	do_nothing();
+
+	if (copy_to_user((void __user *)dst, do_nothing, EXEC_SIZE))
+		return;
+	flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE);
+	pr_info("attempting bad execution at %p\n", func);
+	func();
+}
+
+static void lkdtm_do_action(enum ctype which)
+{
+	switch (which) {
+	case CT_PANIC:
+		panic("dumptest");
+		break;
+	case CT_BUG:
+		BUG();
+		break;
+	case CT_WARNING:
+		WARN_ON(1);
+		break;
+	case CT_EXCEPTION:
+		*((int *) 0) = 0;
+		break;
+	case CT_LOOP:
+		for (;;)
+			;
+		break;
+	case CT_OVERFLOW:
+		(void) recursive_loop(recur_count);
+		break;
+	case CT_CORRUPT_STACK:
+		corrupt_stack();
+		break;
+	case CT_UNALIGNED_LOAD_STORE_WRITE: {
+		static u8 data[5] __attribute__((aligned(4))) = {1, 2,
+				3, 4, 5};
+		u32 *p;
+		u32 val = 0x12345678;
+
+		p = (u32 *)(data + 1);
+		if (*p == 0)
+			val = 0x87654321;
+		*p = val;
+		 break;
+	}
+	case CT_OVERWRITE_ALLOCATION: {
+		size_t len = 1020;
+		u32 *data = kmalloc(len, GFP_KERNEL);
+
+		data[1024 / sizeof(u32)] = 0x12345678;
+		kfree(data);
+		break;
+	}
+	case CT_WRITE_AFTER_FREE: {
+		int *base, *again;
+		size_t len = 1024;
+		/*
+		 * The slub allocator uses the first word to store the free
+		 * pointer in some configurations. Use the middle of the
+		 * allocation to avoid running into the freelist
+		 */
+		size_t offset = (len / sizeof(*base)) / 2;
+
+		base = kmalloc(len, GFP_KERNEL);
+		pr_info("Allocated memory %p-%p\n", base, &base[offset * 2]);
+		pr_info("Attempting bad write to freed memory at %p\n",
+			&base[offset]);
+		kfree(base);
+		base[offset] = 0x0abcdef0;
+		/* Attempt to notice the overwrite. */
+		again = kmalloc(len, GFP_KERNEL);
+		kfree(again);
+		if (again != base)
+			pr_info("Hmm, didn't get the same memory range.\n");
+
+		break;
+	}
+	case CT_READ_AFTER_FREE: {
+		int *base, *val, saw;
+		size_t len = 1024;
+		/*
+		 * The slub allocator uses the first word to store the free
+		 * pointer in some configurations. Use the middle of the
+		 * allocation to avoid running into the freelist
+		 */
+		size_t offset = (len / sizeof(*base)) / 2;
+
+		base = kmalloc(len, GFP_KERNEL);
+		if (!base)
+			break;
+
+		val = kmalloc(len, GFP_KERNEL);
+		if (!val) {
+			kfree(base);
+			break;
+		}
+
+		*val = 0x12345678;
+		base[offset] = *val;
+		pr_info("Value in memory before free: %x\n", base[offset]);
+
+		kfree(base);
+
+		pr_info("Attempting bad read from freed memory\n");
+		saw = base[offset];
+		if (saw != *val) {
+			/* Good! Poisoning happened, so declare a win. */
+			pr_info("Memory correctly poisoned (%x)\n", saw);
+			BUG();
+		}
+		pr_info("Memory was not poisoned\n");
+
+		kfree(val);
+		break;
+	}
+	case CT_WRITE_BUDDY_AFTER_FREE: {
+		unsigned long p = __get_free_page(GFP_KERNEL);
+		if (!p)
+			break;
+		pr_info("Writing to the buddy page before free\n");
+		memset((void *)p, 0x3, PAGE_SIZE);
+		free_page(p);
+		schedule();
+		pr_info("Attempting bad write to the buddy page after free\n");
+		memset((void *)p, 0x78, PAGE_SIZE);
+		/* Attempt to notice the overwrite. */
+		p = __get_free_page(GFP_KERNEL);
+		free_page(p);
+		schedule();
+
+		break;
+	}
+	case CT_READ_BUDDY_AFTER_FREE: {
+		unsigned long p = __get_free_page(GFP_KERNEL);
+		int saw, *val;
+		int *base;
+
+		if (!p)
+			break;
+
+		val = kmalloc(1024, GFP_KERNEL);
+		if (!val) {
+			free_page(p);
+			break;
+		}
+
+		base = (int *)p;
+
+		*val = 0x12345678;
+		base[0] = *val;
+		pr_info("Value in memory before free: %x\n", base[0]);
+		free_page(p);
+		pr_info("Attempting to read from freed memory\n");
+		saw = base[0];
+		if (saw != *val) {
+			/* Good! Poisoning happened, so declare a win. */
+			pr_info("Memory correctly poisoned (%x)\n", saw);
+			BUG();
+		}
+		pr_info("Buddy page was not poisoned\n");
+
+		kfree(val);
+		break;
+	}
+	case CT_SOFTLOCKUP:
+		preempt_disable();
+		for (;;)
+			cpu_relax();
+		break;
+	case CT_HARDLOCKUP:
+		local_irq_disable();
+		for (;;)
+			cpu_relax();
+		break;
+	case CT_SPINLOCKUP:
+		/* Must be called twice to trigger. */
+		spin_lock(&lock_me_up);
+		/* Let sparse know we intended to exit holding the lock. */
+		__release(&lock_me_up);
+		break;
+	case CT_HUNG_TASK:
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		schedule();
+		break;
+	case CT_EXEC_DATA:
+		execute_location(data_area);
+		break;
+	case CT_EXEC_STACK: {
+		u8 stack_area[EXEC_SIZE];
+		execute_location(stack_area);
+		break;
+	}
+	case CT_EXEC_KMALLOC: {
+		u32 *kmalloc_area = kmalloc(EXEC_SIZE, GFP_KERNEL);
+		execute_location(kmalloc_area);
+		kfree(kmalloc_area);
+		break;
+	}
+	case CT_EXEC_VMALLOC: {
+		u32 *vmalloc_area = vmalloc(EXEC_SIZE);
+		execute_location(vmalloc_area);
+		vfree(vmalloc_area);
+		break;
+	}
+	case CT_EXEC_USERSPACE: {
+		unsigned long user_addr;
+
+		user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
+				    PROT_READ | PROT_WRITE | PROT_EXEC,
+				    MAP_ANONYMOUS | MAP_PRIVATE, 0);
+		if (user_addr >= TASK_SIZE) {
+			pr_warn("Failed to allocate user memory\n");
+			return;
+		}
+		execute_user_location((void *)user_addr);
+		vm_munmap(user_addr, PAGE_SIZE);
+		break;
+	}
+	case CT_ACCESS_USERSPACE: {
+		unsigned long user_addr, tmp = 0;
+		unsigned long *ptr;
+
+		user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
+				    PROT_READ | PROT_WRITE | PROT_EXEC,
+				    MAP_ANONYMOUS | MAP_PRIVATE, 0);
+		if (user_addr >= TASK_SIZE) {
+			pr_warn("Failed to allocate user memory\n");
+			return;
+		}
+
+		if (copy_to_user((void __user *)user_addr, &tmp, sizeof(tmp))) {
+			pr_warn("copy_to_user failed\n");
+			vm_munmap(user_addr, PAGE_SIZE);
+			return;
+		}
+
+		ptr = (unsigned long *)user_addr;
+
+		pr_info("attempting bad read at %p\n", ptr);
+		tmp = *ptr;
+		tmp += 0xc0dec0de;
+
+		pr_info("attempting bad write at %p\n", ptr);
+		*ptr = tmp;
+
+		vm_munmap(user_addr, PAGE_SIZE);
+
+		break;
+	}
+	case CT_WRITE_RO: {
+		/* Explicitly cast away "const" for the test. */
+		unsigned long *ptr = (unsigned long *)&rodata;
+
+		pr_info("attempting bad rodata write at %p\n", ptr);
+		*ptr ^= 0xabcd1234;
+
+		break;
+	}
+	case CT_WRITE_RO_AFTER_INIT: {
+		unsigned long *ptr = &ro_after_init;
+
+		/*
+		 * Verify we were written to during init. Since an Oops
+		 * is considered a "success", a failure is to just skip the
+		 * real test.
+		 */
+		if ((*ptr & 0xAA) != 0xAA) {
+			pr_info("%p was NOT written during init!?\n", ptr);
+			break;
+		}
+
+		pr_info("attempting bad ro_after_init write at %p\n", ptr);
+		*ptr ^= 0xabcd1234;
+
+		break;
+	}
+	case CT_WRITE_KERN: {
+		size_t size;
+		unsigned char *ptr;
+
+		size = (unsigned long)do_overwritten -
+		       (unsigned long)do_nothing;
+		ptr = (unsigned char *)do_overwritten;
+
+		pr_info("attempting bad %zu byte write at %p\n", size, ptr);
+		memcpy(ptr, (unsigned char *)do_nothing, size);
+		flush_icache_range((unsigned long)ptr,
+				   (unsigned long)(ptr + size));
+
+		do_overwritten();
+		break;
+	}
+	case CT_WRAP_ATOMIC: {
+		atomic_t under = ATOMIC_INIT(INT_MIN);
+		atomic_t over = ATOMIC_INIT(INT_MAX);
+
+		pr_info("attempting atomic underflow\n");
+		atomic_dec(&under);
+		pr_info("attempting atomic overflow\n");
+		atomic_inc(&over);
+
+		return;
+	}
+	case CT_NONE:
+	default:
+		break;
+	}
+
+}
+
+static void lkdtm_handler(void)
+{
+	unsigned long flags;
+	bool do_it = false;
+
+	spin_lock_irqsave(&count_lock, flags);
+	count--;
+	pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",
+		cp_name_to_str(cpoint), cp_type_to_str(cptype), count);
+
+	if (count == 0) {
+		do_it = true;
+		count = cpoint_count;
+	}
+	spin_unlock_irqrestore(&count_lock, flags);
+
+	if (do_it)
+		lkdtm_do_action(cptype);
+}
+
+static int lkdtm_register_cpoint(enum cname which)
+{
+	int ret;
+
+	cpoint = CN_INVALID;
+	if (lkdtm.entry != NULL)
+		unregister_jprobe(&lkdtm);
+
+	switch (which) {
+	case CN_DIRECT:
+		lkdtm_do_action(cptype);
+		return 0;
+	case CN_INT_HARDWARE_ENTRY:
+		lkdtm.kp.symbol_name = "do_IRQ";
+		lkdtm.entry = (kprobe_opcode_t*) jp_do_irq;
+		break;
+	case CN_INT_HW_IRQ_EN:
+		lkdtm.kp.symbol_name = "handle_IRQ_event";
+		lkdtm.entry = (kprobe_opcode_t*) jp_handle_irq_event;
+		break;
+	case CN_INT_TASKLET_ENTRY:
+		lkdtm.kp.symbol_name = "tasklet_action";
+		lkdtm.entry = (kprobe_opcode_t*) jp_tasklet_action;
+		break;
+	case CN_FS_DEVRW:
+		lkdtm.kp.symbol_name = "ll_rw_block";
+		lkdtm.entry = (kprobe_opcode_t*) jp_ll_rw_block;
+		break;
+	case CN_MEM_SWAPOUT:
+		lkdtm.kp.symbol_name = "shrink_inactive_list";
+		lkdtm.entry = (kprobe_opcode_t*) jp_shrink_inactive_list;
+		break;
+	case CN_TIMERADD:
+		lkdtm.kp.symbol_name = "hrtimer_start";
+		lkdtm.entry = (kprobe_opcode_t*) jp_hrtimer_start;
+		break;
+	case CN_SCSI_DISPATCH_CMD:
+		lkdtm.kp.symbol_name = "scsi_dispatch_cmd";
+		lkdtm.entry = (kprobe_opcode_t*) jp_scsi_dispatch_cmd;
+		break;
+	case CN_IDE_CORE_CP:
+#ifdef CONFIG_IDE
+		lkdtm.kp.symbol_name = "generic_ide_ioctl";
+		lkdtm.entry = (kprobe_opcode_t*) jp_generic_ide_ioctl;
+#else
+		pr_info("Crash point not available\n");
+		return -EINVAL;
+#endif
+		break;
+	default:
+		pr_info("Invalid Crash Point\n");
+		return -EINVAL;
+	}
+
+	cpoint = which;
+	if ((ret = register_jprobe(&lkdtm)) < 0) {
+		pr_info("Couldn't register jprobe\n");
+		cpoint = CN_INVALID;
+	}
+
+	return ret;
+}
+
+static ssize_t do_register_entry(enum cname which, struct file *f,
+		const char __user *user_buf, size_t count, loff_t *off)
+{
+	char *buf;
+	int err;
+
+	if (count >= PAGE_SIZE)
+		return -EINVAL;
+
+	buf = (char *)__get_free_page(GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+	if (copy_from_user(buf, user_buf, count)) {
+		free_page((unsigned long) buf);
+		return -EFAULT;
+	}
+	/* NULL-terminate and remove enter */
+	buf[count] = '\0';
+	strim(buf);
+
+	cptype = parse_cp_type(buf, count);
+	free_page((unsigned long) buf);
+
+	if (cptype == CT_NONE)
+		return -EINVAL;
+
+	err = lkdtm_register_cpoint(which);
+	if (err < 0)
+		return err;
+
+	*off += count;
+
+	return count;
+}
+
+/* Generic read callback that just prints out the available crash types */
+static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
+		size_t count, loff_t *off)
+{
+	char *buf;
+	int i, n, out;
+
+	buf = (char *)__get_free_page(GFP_KERNEL);
+	if (buf == NULL)
+		return -ENOMEM;
+
+	n = snprintf(buf, PAGE_SIZE, "Available crash types:\n");
+	for (i = 0; i < ARRAY_SIZE(cp_type); i++)
+		n += snprintf(buf + n, PAGE_SIZE - n, "%s\n", cp_type[i]);
+	buf[n] = '\0';
+
+	out = simple_read_from_buffer(user_buf, count, off,
+				      buf, n);
+	free_page((unsigned long) buf);
+
+	return out;
+}
+
+static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
+{
+	return 0;
+}
+
+
+static ssize_t int_hardware_entry(struct file *f, const char __user *buf,
+		size_t count, loff_t *off)
+{
+	return do_register_entry(CN_INT_HARDWARE_ENTRY, f, buf, count, off);
+}
+
+static ssize_t int_hw_irq_en(struct file *f, const char __user *buf,
+		size_t count, loff_t *off)
+{
+	return do_register_entry(CN_INT_HW_IRQ_EN, f, buf, count, off);
+}
+
+static ssize_t int_tasklet_entry(struct file *f, const char __user *buf,
+		size_t count, loff_t *off)
+{
+	return do_register_entry(CN_INT_TASKLET_ENTRY, f, buf, count, off);
+}
+
+static ssize_t fs_devrw_entry(struct file *f, const char __user *buf,
+		size_t count, loff_t *off)
+{
+	return do_register_entry(CN_FS_DEVRW, f, buf, count, off);
+}
+
+static ssize_t mem_swapout_entry(struct file *f, const char __user *buf,
+		size_t count, loff_t *off)
+{
+	return do_register_entry(CN_MEM_SWAPOUT, f, buf, count, off);
+}
+
+static ssize_t timeradd_entry(struct file *f, const char __user *buf,
+		size_t count, loff_t *off)
+{
+	return do_register_entry(CN_TIMERADD, f, buf, count, off);
+}
+
+static ssize_t scsi_dispatch_cmd_entry(struct file *f,
+		const char __user *buf, size_t count, loff_t *off)
+{
+	return do_register_entry(CN_SCSI_DISPATCH_CMD, f, buf, count, off);
+}
+
+static ssize_t ide_core_cp_entry(struct file *f, const char __user *buf,
+		size_t count, loff_t *off)
+{
+	return do_register_entry(CN_IDE_CORE_CP, f, buf, count, off);
+}
+
+/* Special entry to just crash directly. Available without KPROBEs */
+static ssize_t direct_entry(struct file *f, const char __user *user_buf,
+		size_t count, loff_t *off)
+{
+	enum ctype type;
+	char *buf;
+
+	if (count >= PAGE_SIZE)
+		return -EINVAL;
+	if (count < 1)
+		return -EINVAL;
+
+	buf = (char *)__get_free_page(GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+	if (copy_from_user(buf, user_buf, count)) {
+		free_page((unsigned long) buf);
+		return -EFAULT;
+	}
+	/* NULL-terminate and remove enter */
+	buf[count] = '\0';
+	strim(buf);
+
+	type = parse_cp_type(buf, count);
+	free_page((unsigned long) buf);
+	if (type == CT_NONE)
+		return -EINVAL;
+
+	pr_info("Performing direct entry %s\n", cp_type_to_str(type));
+	lkdtm_do_action(type);
+	*off += count;
+
+	return count;
+}
+
+struct crash_entry {
+	const char *name;
+	const struct file_operations fops;
+};
+
+static const struct crash_entry crash_entries[] = {
+	{"DIRECT", {.read = lkdtm_debugfs_read,
+			.llseek = generic_file_llseek,
+			.open = lkdtm_debugfs_open,
+			.write = direct_entry} },
+	{"INT_HARDWARE_ENTRY", {.read = lkdtm_debugfs_read,
+			.llseek = generic_file_llseek,
+			.open = lkdtm_debugfs_open,
+			.write = int_hardware_entry} },
+	{"INT_HW_IRQ_EN", {.read = lkdtm_debugfs_read,
+			.llseek = generic_file_llseek,
+			.open = lkdtm_debugfs_open,
+			.write = int_hw_irq_en} },
+	{"INT_TASKLET_ENTRY", {.read = lkdtm_debugfs_read,
+			.llseek = generic_file_llseek,
+			.open = lkdtm_debugfs_open,
+			.write = int_tasklet_entry} },
+	{"FS_DEVRW", {.read = lkdtm_debugfs_read,
+			.llseek = generic_file_llseek,
+			.open = lkdtm_debugfs_open,
+			.write = fs_devrw_entry} },
+	{"MEM_SWAPOUT", {.read = lkdtm_debugfs_read,
+			.llseek = generic_file_llseek,
+			.open = lkdtm_debugfs_open,
+			.write = mem_swapout_entry} },
+	{"TIMERADD", {.read = lkdtm_debugfs_read,
+			.llseek = generic_file_llseek,
+			.open = lkdtm_debugfs_open,
+			.write = timeradd_entry} },
+	{"SCSI_DISPATCH_CMD", {.read = lkdtm_debugfs_read,
+			.llseek = generic_file_llseek,
+			.open = lkdtm_debugfs_open,
+			.write = scsi_dispatch_cmd_entry} },
+	{"IDE_CORE_CP",	{.read = lkdtm_debugfs_read,
+			.llseek = generic_file_llseek,
+			.open = lkdtm_debugfs_open,
+			.write = ide_core_cp_entry} },
+};
+
+static struct dentry *lkdtm_debugfs_root;
+
+static int __init lkdtm_module_init(void)
+{
+	int ret = -EINVAL;
+	int n_debugfs_entries = 1; /* Assume only the direct entry */
+	int i;
+
+	/* Make sure we can write to __ro_after_init values during __init */
+	ro_after_init |= 0xAA;
+
+	/* Register debugfs interface */
+	lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
+	if (!lkdtm_debugfs_root) {
+		pr_err("creating root dir failed\n");
+		return -ENODEV;
+	}
+
+#ifdef CONFIG_KPROBES
+	n_debugfs_entries = ARRAY_SIZE(crash_entries);
+#endif
+
+	for (i = 0; i < n_debugfs_entries; i++) {
+		const struct crash_entry *cur = &crash_entries[i];
+		struct dentry *de;
+
+		de = debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root,
+				NULL, &cur->fops);
+		if (de == NULL) {
+			pr_err("could not create %s\n", cur->name);
+			goto out_err;
+		}
+	}
+
+	if (lkdtm_parse_commandline() == -EINVAL) {
+		pr_info("Invalid command\n");
+		goto out_err;
+	}
+
+	if (cpoint != CN_INVALID && cptype != CT_NONE) {
+		ret = lkdtm_register_cpoint(cpoint);
+		if (ret < 0) {
+			pr_info("Invalid crash point %d\n", cpoint);
+			goto out_err;
+		}
+		pr_info("Crash point %s of type %s registered\n",
+			cpoint_name, cpoint_type);
+	} else {
+		pr_info("No crash points registered, enable through debugfs\n");
+	}
+
+	return 0;
+
+out_err:
+	debugfs_remove_recursive(lkdtm_debugfs_root);
+	return ret;
+}
+
+static void __exit lkdtm_module_exit(void)
+{
+	debugfs_remove_recursive(lkdtm_debugfs_root);
+
+	unregister_jprobe(&lkdtm);
+	pr_info("Crash point unregistered\n");
+}
+
+module_init(lkdtm_module_init);
+module_exit(lkdtm_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Kprobe module for testing crash dumps");
-- 
2.7.4

[PATCH 2/5] lkdtm: clean up after rename

[Kees Cook]

This cleans up comments a bit to improve readability, adjusts the
name of the module after the source file renaming, and corrects the
MAINTAINERS for the upcoming lkdtm files.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 MAINTAINERS               |  2 +-
 drivers/misc/lkdtm_core.c | 12 ++++++------
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index ed42cb65a19b..437e291a7b30 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6953,7 +6953,7 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching.git
 LINUX KERNEL DUMP TEST MODULE (LKDTM)
 M:	Kees Cook <keescook@chromium.org>
 S:	Maintained
-F:	drivers/misc/lkdtm.c
+F:	drivers/misc/lkdtm*
 
 LLC (802.2)
 M:	Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
index 0a5cbbe12452..605050c60f10 100644
--- a/drivers/misc/lkdtm_core.c
+++ b/drivers/misc/lkdtm_core.c
@@ -1,5 +1,9 @@
 /*
- * Kprobe module for testing crash dumps
+ * Linux Kernel Dump Test Module for testing kernel crashes conditions:
+ * induces system failures at predefined crashpoints and under predefined
+ * operational conditions in order to evaluate the reliability of kernel
+ * sanity checking and crash dumps obtained using different dumping
+ * solutions.
  *
  * 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
@@ -19,10 +23,6 @@
  *
  * Author: Ankita Garg <ankita@in.ibm.com>
  *
- * This module induces system failures at predefined crashpoints to
- * evaluate the reliability of crash dumps obtained using different dumping
- * solutions.
- *
  * It is adapted from the Linux Kernel Dump Test Tool by
  * Fernando Luis Vazquez Cao <http://lkdtt.sourceforge.net>
  *
@@ -30,7 +30,7 @@
  *
  * See Documentation/fault-injection/provoke-crashes.txt for instructions
  */
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#define pr_fmt(fmt) "lkdtm: " fmt
 
 #include <linux/kernel.h>
 #include <linux/fs.h>
-- 
2.7.4

[PATCH 3/5] lkdtm: add function for testing .rodata section

[Kees Cook]

This adds a function that lives in the .rodata section. The section
flags are corrected using objcopy since there is no way with gcc to
declare section flags in an architecture-agnostic way.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/misc/Makefile       |  7 +++++++
 drivers/misc/lkdtm.h        |  6 ++++++
 drivers/misc/lkdtm_core.c   | 24 +++++++++++++++++-------
 drivers/misc/lkdtm_rodata.c | 10 ++++++++++
 4 files changed, 40 insertions(+), 7 deletions(-)
 create mode 100644 drivers/misc/lkdtm.h
 create mode 100644 drivers/misc/lkdtm_rodata.c

diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index c3cb6ad8cc37..b2d3d68dfa22 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -59,3 +59,10 @@ obj-$(CONFIG_CXL_BASE)		+= cxl/
 obj-$(CONFIG_PANEL)             += panel.o
 
 lkdtm-$(CONFIG_LKDTM)		+= lkdtm_core.o
+lkdtm-$(CONFIG_LKDTM)		+= lkdtm_rodata_objcopy.o
+
+OBJCOPYFLAGS_lkdtm_rodata_objcopy.o := \
+			--set-section-flags .text=alloc,readonly \
+			--rename-section .text=.rodata
+$(obj)/lkdtm_rodata_objcopy.o: $(obj)/lkdtm_rodata.o
+	$(call if_changed,objcopy)
diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h
new file mode 100644
index 000000000000..9531fa3be4c3
--- /dev/null
+++ b/drivers/misc/lkdtm.h
@@ -0,0 +1,6 @@
+#ifndef __LKDTM_H
+#define __LKDTM_H
+
+void lkdtm_rodata_do_nothing(void);
+
+#endif
diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
index 605050c60f10..187cd9b63e9a 100644
--- a/drivers/misc/lkdtm_core.c
+++ b/drivers/misc/lkdtm_core.c
@@ -52,6 +52,8 @@
 #include <linux/ide.h>
 #endif
 
+#include "lkdtm.h"
+
 /*
  * Make sure our attempts to over run the kernel stack doesn't trigger
  * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we
@@ -103,6 +105,7 @@ enum ctype {
 	CT_EXEC_STACK,
 	CT_EXEC_KMALLOC,
 	CT_EXEC_VMALLOC,
+	CT_EXEC_RODATA,
 	CT_EXEC_USERSPACE,
 	CT_ACCESS_USERSPACE,
 	CT_WRITE_RO,
@@ -145,6 +148,7 @@ static char* cp_type[] = {
 	"EXEC_STACK",
 	"EXEC_KMALLOC",
 	"EXEC_VMALLOC",
+	"EXEC_RODATA",
 	"EXEC_USERSPACE",
 	"ACCESS_USERSPACE",
 	"WRITE_RO",
@@ -346,15 +350,18 @@ static noinline void corrupt_stack(void)
 	memset((void *)data, 0, 64);
 }
 
-static void noinline execute_location(void *dst)
+static noinline void execute_location(void *dst, bool write)
 {
 	void (*func)(void) = dst;
 
 	pr_info("attempting ok execution at %p\n", do_nothing);
 	do_nothing();
 
-	memcpy(dst, do_nothing, EXEC_SIZE);
-	flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE);
+	if (write) {
+		memcpy(dst, do_nothing, EXEC_SIZE);
+		flush_icache_range((unsigned long)dst,
+				   (unsigned long)dst + EXEC_SIZE);
+	}
 	pr_info("attempting bad execution at %p\n", func);
 	func();
 }
@@ -551,25 +558,28 @@ static void lkdtm_do_action(enum ctype which)
 		schedule();
 		break;
 	case CT_EXEC_DATA:
-		execute_location(data_area);
+		execute_location(data_area, true);
 		break;
 	case CT_EXEC_STACK: {
 		u8 stack_area[EXEC_SIZE];
-		execute_location(stack_area);
+		execute_location(stack_area, true);
 		break;
 	}
 	case CT_EXEC_KMALLOC: {
 		u32 *kmalloc_area = kmalloc(EXEC_SIZE, GFP_KERNEL);
-		execute_location(kmalloc_area);
+		execute_location(kmalloc_area, true);
 		kfree(kmalloc_area);
 		break;
 	}
 	case CT_EXEC_VMALLOC: {
 		u32 *vmalloc_area = vmalloc(EXEC_SIZE);
-		execute_location(vmalloc_area);
+		execute_location(vmalloc_area, true);
 		vfree(vmalloc_area);
 		break;
 	}
+	case CT_EXEC_RODATA:
+		execute_location(lkdtm_rodata_do_nothing, false);
+		break;
 	case CT_EXEC_USERSPACE: {
 		unsigned long user_addr;
 
diff --git a/drivers/misc/lkdtm_rodata.c b/drivers/misc/lkdtm_rodata.c
new file mode 100644
index 000000000000..4d0d851f02b9
--- /dev/null
+++ b/drivers/misc/lkdtm_rodata.c
@@ -0,0 +1,10 @@
+/*
+ * This includes functions that are meant to live entirely in .rodata
+ * (via objcopy tricks), to validate the non-executability of .rodata.
+ */
+#include <linux/kernel.h>
+
+void lkdtm_rodata_do_nothing(void)
+{
+	/* Does nothing. We just want an architecture agnostic "return". */
+}
-- 
2.7.4

Re: [PATCH 3/5] lkdtm: add function for testing .rodata section

[Laura Abbott]

On 06/07/2016 02:57 PM, Kees Cook wrote:
> This adds a function that lives in the .rodata section. The section
> flags are corrected using objcopy since there is no way with gcc to
> declare section flags in an architecture-agnostic way.
>

Permit me to be the bearer of bad architecture news once again. With
arm64 cross compiler (both Fedora 6.1.1 and Linaro 5.1)

   CC      drivers/misc/lkdtm_rodata.o
   OBJCOPY drivers/misc/lkdtm_rodata_objcopy.o
   LD      drivers/misc/lkdtm.o
drivers/misc/lkdtm_rodata_objcopy.o: file not recognized: File format not recognized
scripts/Makefile.build:423: recipe for target 'drivers/misc/lkdtm.o' failed
make[2]: *** [drivers/misc/lkdtm.o] Error 1
scripts/Makefile.build:440: recipe for target 'drivers/misc' failed
make[1]: *** [drivers/misc] Error 2
Makefile:985: recipe for target 'drivers' failed
make: *** [drivers] Error 2


As far as I can tell this is because arm64 defines OBJCOPYFLAGS and they get
propagated to objcopy

aarch64-linux-gnu-objcopy -O binary -R .note -R .note.gnu.build-id -R .comment
	-S --set-section-flags .text=alloc,readonly
	--rename-section .text=.rodata drivers/misc/lkdtm_rodata.o drivers/misc/lkdtm_rodata_objcopy.o

vs x86

objcopy  --set-section-flags .text=alloc,readonly --rename-section .text=.rodata
	drivers/misc/lkdtm_rodata.o drivers/misc/lkdtm_rodata_objcopy.o


specifically it's the -O binary that seems to break things, the same failure
happens on x86 as well with the the same commands. It works if I clear out
the OBJCOPYFLAGS variable first but I don't think that's the correct way to
fix this.

Thanks,
Laura

> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  drivers/misc/Makefile       |  7 +++++++
>  drivers/misc/lkdtm.h        |  6 ++++++
>  drivers/misc/lkdtm_core.c   | 24 +++++++++++++++++-------
>  drivers/misc/lkdtm_rodata.c | 10 ++++++++++
>  4 files changed, 40 insertions(+), 7 deletions(-)
>  create mode 100644 drivers/misc/lkdtm.h
>  create mode 100644 drivers/misc/lkdtm_rodata.c
>
> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
> index c3cb6ad8cc37..b2d3d68dfa22 100644
> --- a/drivers/misc/Makefile
> +++ b/drivers/misc/Makefile
> @@ -59,3 +59,10 @@ obj-$(CONFIG_CXL_BASE)		+= cxl/
>  obj-$(CONFIG_PANEL)             += panel.o
>
>  lkdtm-$(CONFIG_LKDTM)		+= lkdtm_core.o
> +lkdtm-$(CONFIG_LKDTM)		+= lkdtm_rodata_objcopy.o
> +
> +OBJCOPYFLAGS_lkdtm_rodata_objcopy.o := \
> +			--set-section-flags .text=alloc,readonly \
> +			--rename-section .text=.rodata
> +$(obj)/lkdtm_rodata_objcopy.o: $(obj)/lkdtm_rodata.o
> +	$(call if_changed,objcopy)
> diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h
> new file mode 100644
> index 000000000000..9531fa3be4c3
> --- /dev/null
> +++ b/drivers/misc/lkdtm.h
> @@ -0,0 +1,6 @@
> +#ifndef __LKDTM_H
> +#define __LKDTM_H
> +
> +void lkdtm_rodata_do_nothing(void);
> +
> +#endif
> diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
> index 605050c60f10..187cd9b63e9a 100644
> --- a/drivers/misc/lkdtm_core.c
> +++ b/drivers/misc/lkdtm_core.c
> @@ -52,6 +52,8 @@
>  #include <linux/ide.h>
>  #endif
>
> +#include "lkdtm.h"
> +
>  /*
>   * Make sure our attempts to over run the kernel stack doesn't trigger
>   * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we
> @@ -103,6 +105,7 @@ enum ctype {
>  	CT_EXEC_STACK,
>  	CT_EXEC_KMALLOC,
>  	CT_EXEC_VMALLOC,
> +	CT_EXEC_RODATA,
>  	CT_EXEC_USERSPACE,
>  	CT_ACCESS_USERSPACE,
>  	CT_WRITE_RO,
> @@ -145,6 +148,7 @@ static char* cp_type[] = {
>  	"EXEC_STACK",
>  	"EXEC_KMALLOC",
>  	"EXEC_VMALLOC",
> +	"EXEC_RODATA",
>  	"EXEC_USERSPACE",
>  	"ACCESS_USERSPACE",
>  	"WRITE_RO",
> @@ -346,15 +350,18 @@ static noinline void corrupt_stack(void)
>  	memset((void *)data, 0, 64);
>  }
>
> -static void noinline execute_location(void *dst)
> +static noinline void execute_location(void *dst, bool write)
>  {
>  	void (*func)(void) = dst;
>
>  	pr_info("attempting ok execution at %p\n", do_nothing);
>  	do_nothing();
>
> -	memcpy(dst, do_nothing, EXEC_SIZE);
> -	flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE);
> +	if (write) {
> +		memcpy(dst, do_nothing, EXEC_SIZE);
> +		flush_icache_range((unsigned long)dst,
> +				   (unsigned long)dst + EXEC_SIZE);
> +	}
>  	pr_info("attempting bad execution at %p\n", func);
>  	func();
>  }
> @@ -551,25 +558,28 @@ static void lkdtm_do_action(enum ctype which)
>  		schedule();
>  		break;
>  	case CT_EXEC_DATA:
> -		execute_location(data_area);
> +		execute_location(data_area, true);
>  		break;
>  	case CT_EXEC_STACK: {
>  		u8 stack_area[EXEC_SIZE];
> -		execute_location(stack_area);
> +		execute_location(stack_area, true);
>  		break;
>  	}
>  	case CT_EXEC_KMALLOC: {
>  		u32 *kmalloc_area = kmalloc(EXEC_SIZE, GFP_KERNEL);
> -		execute_location(kmalloc_area);
> +		execute_location(kmalloc_area, true);
>  		kfree(kmalloc_area);
>  		break;
>  	}
>  	case CT_EXEC_VMALLOC: {
>  		u32 *vmalloc_area = vmalloc(EXEC_SIZE);
> -		execute_location(vmalloc_area);
> +		execute_location(vmalloc_area, true);
>  		vfree(vmalloc_area);
>  		break;
>  	}
> +	case CT_EXEC_RODATA:
> +		execute_location(lkdtm_rodata_do_nothing, false);
> +		break;
>  	case CT_EXEC_USERSPACE: {
>  		unsigned long user_addr;
>
> diff --git a/drivers/misc/lkdtm_rodata.c b/drivers/misc/lkdtm_rodata.c
> new file mode 100644
> index 000000000000..4d0d851f02b9
> --- /dev/null
> +++ b/drivers/misc/lkdtm_rodata.c
> @@ -0,0 +1,10 @@
> +/*
> + * This includes functions that are meant to live entirely in .rodata
> + * (via objcopy tricks), to validate the non-executability of .rodata.
> + */
> +#include <linux/kernel.h>
> +
> +void lkdtm_rodata_do_nothing(void)
> +{
> +	/* Does nothing. We just want an architecture agnostic "return". */
> +}
>

Re: [PATCH 3/5] lkdtm: add function for testing .rodata section

[Kees Cook]

On Tue, Jun 7, 2016 at 6:02 PM, Laura Abbott <labbott@redhat.com> wrote:
> On 06/07/2016 02:57 PM, Kees Cook wrote:
>>
>> This adds a function that lives in the .rodata section. The section
>> flags are corrected using objcopy since there is no way with gcc to
>> declare section flags in an architecture-agnostic way.
>>
>
> Permit me to be the bearer of bad architecture news once again. With
> arm64 cross compiler (both Fedora 6.1.1 and Linaro 5.1)
>
>   CC      drivers/misc/lkdtm_rodata.o
>   OBJCOPY drivers/misc/lkdtm_rodata_objcopy.o
>   LD      drivers/misc/lkdtm.o
> drivers/misc/lkdtm_rodata_objcopy.o: file not recognized: File format not
> recognized
> scripts/Makefile.build:423: recipe for target 'drivers/misc/lkdtm.o' failed
> make[2]: *** [drivers/misc/lkdtm.o] Error 1
> scripts/Makefile.build:440: recipe for target 'drivers/misc' failed
> make[1]: *** [drivers/misc] Error 2
> Makefile:985: recipe for target 'drivers' failed
> make: *** [drivers] Error 2
>
>
> As far as I can tell this is because arm64 defines OBJCOPYFLAGS and they get
> propagated to objcopy
>
> aarch64-linux-gnu-objcopy -O binary -R .note -R .note.gnu.build-id -R
> .comment
>         -S --set-section-flags .text=alloc,readonly
>         --rename-section .text=.rodata drivers/misc/lkdtm_rodata.o
> drivers/misc/lkdtm_rodata_objcopy.o
>
> vs x86
>
> objcopy  --set-section-flags .text=alloc,readonly --rename-section
> .text=.rodata
>         drivers/misc/lkdtm_rodata.o drivers/misc/lkdtm_rodata_objcopy.o
>
>
> specifically it's the -O binary that seems to break things, the same failure
> happens on x86 as well with the the same commands. It works if I clear out
> the OBJCOPYFLAGS variable first but I don't think that's the correct way to
> fix this.
>
> Thanks,
> Laura
>
>
>> Signed-off-by: Kees Cook <keescook@chromium.org>
>> ---
>>  drivers/misc/Makefile       |  7 +++++++
>>  drivers/misc/lkdtm.h        |  6 ++++++
>>  drivers/misc/lkdtm_core.c   | 24 +++++++++++++++++-------
>>  drivers/misc/lkdtm_rodata.c | 10 ++++++++++
>>  4 files changed, 40 insertions(+), 7 deletions(-)
>>  create mode 100644 drivers/misc/lkdtm.h
>>  create mode 100644 drivers/misc/lkdtm_rodata.c
>>
>> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
>> index c3cb6ad8cc37..b2d3d68dfa22 100644
>> --- a/drivers/misc/Makefile
>> +++ b/drivers/misc/Makefile
>> @@ -59,3 +59,10 @@ obj-$(CONFIG_CXL_BASE)               += cxl/
>>  obj-$(CONFIG_PANEL)             += panel.o
>>
>>  lkdtm-$(CONFIG_LKDTM)          += lkdtm_core.o
>> +lkdtm-$(CONFIG_LKDTM)          += lkdtm_rodata_objcopy.o
>> +
>> +OBJCOPYFLAGS_lkdtm_rodata_objcopy.o := \
>> +                       --set-section-flags .text=alloc,readonly \
>> +                       --rename-section .text=.rodata
>> +$(obj)/lkdtm_rodata_objcopy.o: $(obj)/lkdtm_rodata.o
>> +       $(call if_changed,objcopy)

Uhhhh... How is arm64 injecting those extra flags? OBJCOPYFLAGS is
being set with := here?

In related news I need to figure out how to get my cross-compiler
builds more well scripted...

-Kees

-- 
Kees Cook
Chrome OS & Brillo Security

Re: [PATCH 3/5] lkdtm: add function for testing .rodata section

[Laura Abbott]

On 06/08/2016 08:46 AM, Kees Cook wrote:
> On Tue, Jun 7, 2016 at 6:02 PM, Laura Abbott <labbott@redhat.com> wrote:
>> On 06/07/2016 02:57 PM, Kees Cook wrote:
>>>
>>> This adds a function that lives in the .rodata section. The section
>>> flags are corrected using objcopy since there is no way with gcc to
>>> declare section flags in an architecture-agnostic way.
>>>
>>
>> Permit me to be the bearer of bad architecture news once again. With
>> arm64 cross compiler (both Fedora 6.1.1 and Linaro 5.1)
>>
>>   CC      drivers/misc/lkdtm_rodata.o
>>   OBJCOPY drivers/misc/lkdtm_rodata_objcopy.o
>>   LD      drivers/misc/lkdtm.o
>> drivers/misc/lkdtm_rodata_objcopy.o: file not recognized: File format not
>> recognized
>> scripts/Makefile.build:423: recipe for target 'drivers/misc/lkdtm.o' failed
>> make[2]: *** [drivers/misc/lkdtm.o] Error 1
>> scripts/Makefile.build:440: recipe for target 'drivers/misc' failed
>> make[1]: *** [drivers/misc] Error 2
>> Makefile:985: recipe for target 'drivers' failed
>> make: *** [drivers] Error 2
>>
>>
>> As far as I can tell this is because arm64 defines OBJCOPYFLAGS and they get
>> propagated to objcopy
>>
>> aarch64-linux-gnu-objcopy -O binary -R .note -R .note.gnu.build-id -R
>> .comment
>>         -S --set-section-flags .text=alloc,readonly
>>         --rename-section .text=.rodata drivers/misc/lkdtm_rodata.o
>> drivers/misc/lkdtm_rodata_objcopy.o
>>
>> vs x86
>>
>> objcopy  --set-section-flags .text=alloc,readonly --rename-section
>> .text=.rodata
>>         drivers/misc/lkdtm_rodata.o drivers/misc/lkdtm_rodata_objcopy.o
>>
>>
>> specifically it's the -O binary that seems to break things, the same failure
>> happens on x86 as well with the the same commands. It works if I clear out
>> the OBJCOPYFLAGS variable first but I don't think that's the correct way to
>> fix this.
>>
>> Thanks,
>> Laura
>>
>>
>>> Signed-off-by: Kees Cook <keescook@chromium.org>
>>> ---
>>>  drivers/misc/Makefile       |  7 +++++++
>>>  drivers/misc/lkdtm.h        |  6 ++++++
>>>  drivers/misc/lkdtm_core.c   | 24 +++++++++++++++++-------
>>>  drivers/misc/lkdtm_rodata.c | 10 ++++++++++
>>>  4 files changed, 40 insertions(+), 7 deletions(-)
>>>  create mode 100644 drivers/misc/lkdtm.h
>>>  create mode 100644 drivers/misc/lkdtm_rodata.c
>>>
>>> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
>>> index c3cb6ad8cc37..b2d3d68dfa22 100644
>>> --- a/drivers/misc/Makefile
>>> +++ b/drivers/misc/Makefile
>>> @@ -59,3 +59,10 @@ obj-$(CONFIG_CXL_BASE)               += cxl/
>>>  obj-$(CONFIG_PANEL)             += panel.o
>>>
>>>  lkdtm-$(CONFIG_LKDTM)          += lkdtm_core.o
>>> +lkdtm-$(CONFIG_LKDTM)          += lkdtm_rodata_objcopy.o
>>> +
>>> +OBJCOPYFLAGS_lkdtm_rodata_objcopy.o := \
>>> +                       --set-section-flags .text=alloc,readonly \
>>> +                       --rename-section .text=.rodata
>>> +$(obj)/lkdtm_rodata_objcopy.o: $(obj)/lkdtm_rodata.o
>>> +       $(call if_changed,objcopy)
>
> Uhhhh... How is arm64 injecting those extra flags? OBJCOPYFLAGS is
> being set with := here?
>

Looks like intended behavior from scripts/Makefile.lib:

# Objcopy
# ---------------------------------------------------------------------------

quiet_cmd_objcopy = OBJCOPY $@
cmd_objcopy = $(OBJCOPY) $(OBJCOPYFLAGS) $(OBJCOPYFLAGS_$(@F)) $< $@

OBJCOPYFLAGS_$@ is separate from OBJCOPYFLAGS which makes sense for the
original intentions although not what we want here. Some Makefile
wizardry is probably needed.

> In related news I need to figure out how to get my cross-compiler
> builds more well scripted...
>
> -Kees
>

Re: [PATCH 3/5] lkdtm: add function for testing .rodata section

[Kees Cook]

On Wed, Jun 8, 2016 at 8:46 AM, Kees Cook <keescook@chromium.org> wrote:
> On Tue, Jun 7, 2016 at 6:02 PM, Laura Abbott <labbott@redhat.com> wrote:
>> On 06/07/2016 02:57 PM, Kees Cook wrote:
>>>
>>> This adds a function that lives in the .rodata section. The section
>>> flags are corrected using objcopy since there is no way with gcc to
>>> declare section flags in an architecture-agnostic way.
>>>
>>
>> Permit me to be the bearer of bad architecture news once again. With
>> arm64 cross compiler (both Fedora 6.1.1 and Linaro 5.1)
>>
>>   CC      drivers/misc/lkdtm_rodata.o
>>   OBJCOPY drivers/misc/lkdtm_rodata_objcopy.o
>>   LD      drivers/misc/lkdtm.o
>> drivers/misc/lkdtm_rodata_objcopy.o: file not recognized: File format not
>> recognized
>> scripts/Makefile.build:423: recipe for target 'drivers/misc/lkdtm.o' failed
>> make[2]: *** [drivers/misc/lkdtm.o] Error 1
>> scripts/Makefile.build:440: recipe for target 'drivers/misc' failed
>> make[1]: *** [drivers/misc] Error 2
>> Makefile:985: recipe for target 'drivers' failed
>> make: *** [drivers] Error 2
>>
>>
>> As far as I can tell this is because arm64 defines OBJCOPYFLAGS and they get
>> propagated to objcopy
>>
>> aarch64-linux-gnu-objcopy -O binary -R .note -R .note.gnu.build-id -R
>> .comment
>>         -S --set-section-flags .text=alloc,readonly
>>         --rename-section .text=.rodata drivers/misc/lkdtm_rodata.o
>> drivers/misc/lkdtm_rodata_objcopy.o
>>
>> vs x86
>>
>> objcopy  --set-section-flags .text=alloc,readonly --rename-section
>> .text=.rodata
>>         drivers/misc/lkdtm_rodata.o drivers/misc/lkdtm_rodata_objcopy.o
>>
>>
>> specifically it's the -O binary that seems to break things, the same failure
>> happens on x86 as well with the the same commands. It works if I clear out
>> the OBJCOPYFLAGS variable first but I don't think that's the correct way to
>> fix this.
>>
>> Thanks,
>> Laura
>>
>>
>>> Signed-off-by: Kees Cook <keescook@chromium.org>
>>> ---
>>>  drivers/misc/Makefile       |  7 +++++++
>>>  drivers/misc/lkdtm.h        |  6 ++++++
>>>  drivers/misc/lkdtm_core.c   | 24 +++++++++++++++++-------
>>>  drivers/misc/lkdtm_rodata.c | 10 ++++++++++
>>>  4 files changed, 40 insertions(+), 7 deletions(-)
>>>  create mode 100644 drivers/misc/lkdtm.h
>>>  create mode 100644 drivers/misc/lkdtm_rodata.c
>>>
>>> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
>>> index c3cb6ad8cc37..b2d3d68dfa22 100644
>>> --- a/drivers/misc/Makefile
>>> +++ b/drivers/misc/Makefile
>>> @@ -59,3 +59,10 @@ obj-$(CONFIG_CXL_BASE)               += cxl/
>>>  obj-$(CONFIG_PANEL)             += panel.o
>>>
>>>  lkdtm-$(CONFIG_LKDTM)          += lkdtm_core.o
>>> +lkdtm-$(CONFIG_LKDTM)          += lkdtm_rodata_objcopy.o
>>> +

If I add:

OBJCOPYFLAGS :=

here, it seems to fix things...

>>> +OBJCOPYFLAGS_lkdtm_rodata_objcopy.o := \
>>> +                       --set-section-flags .text=alloc,readonly \
>>> +                       --rename-section .text=.rodata
>>> +$(obj)/lkdtm_rodata_objcopy.o: $(obj)/lkdtm_rodata.o
>>> +       $(call if_changed,objcopy)
>
> Uhhhh... How is arm64 injecting those extra flags? OBJCOPYFLAGS is
> being set with := here?
>
> In related news I need to figure out how to get my cross-compiler
> builds more well scripted...
>
> -Kees
>
> --
> Kees Cook
> Chrome OS & Brillo Security



-- 
Kees Cook
Chrome OS & Brillo Security

Re: [PATCH 3/5] lkdtm: add function for testing .rodata section

[Laura Abbott]

On 06/08/2016 02:26 PM, Kees Cook wrote:
> On Wed, Jun 8, 2016 at 8:46 AM, Kees Cook <keescook@chromium.org> wrote:
>> On Tue, Jun 7, 2016 at 6:02 PM, Laura Abbott <labbott@redhat.com> wrote:
>>> On 06/07/2016 02:57 PM, Kees Cook wrote:
>>>>
>>>> This adds a function that lives in the .rodata section. The section
>>>> flags are corrected using objcopy since there is no way with gcc to
>>>> declare section flags in an architecture-agnostic way.
>>>>
>>>
>>> Permit me to be the bearer of bad architecture news once again. With
>>> arm64 cross compiler (both Fedora 6.1.1 and Linaro 5.1)
>>>
>>>   CC      drivers/misc/lkdtm_rodata.o
>>>   OBJCOPY drivers/misc/lkdtm_rodata_objcopy.o
>>>   LD      drivers/misc/lkdtm.o
>>> drivers/misc/lkdtm_rodata_objcopy.o: file not recognized: File format not
>>> recognized
>>> scripts/Makefile.build:423: recipe for target 'drivers/misc/lkdtm.o' failed
>>> make[2]: *** [drivers/misc/lkdtm.o] Error 1
>>> scripts/Makefile.build:440: recipe for target 'drivers/misc' failed
>>> make[1]: *** [drivers/misc] Error 2
>>> Makefile:985: recipe for target 'drivers' failed
>>> make: *** [drivers] Error 2
>>>
>>>
>>> As far as I can tell this is because arm64 defines OBJCOPYFLAGS and they get
>>> propagated to objcopy
>>>
>>> aarch64-linux-gnu-objcopy -O binary -R .note -R .note.gnu.build-id -R
>>> .comment
>>>         -S --set-section-flags .text=alloc,readonly
>>>         --rename-section .text=.rodata drivers/misc/lkdtm_rodata.o
>>> drivers/misc/lkdtm_rodata_objcopy.o
>>>
>>> vs x86
>>>
>>> objcopy  --set-section-flags .text=alloc,readonly --rename-section
>>> .text=.rodata
>>>         drivers/misc/lkdtm_rodata.o drivers/misc/lkdtm_rodata_objcopy.o
>>>
>>>
>>> specifically it's the -O binary that seems to break things, the same failure
>>> happens on x86 as well with the the same commands. It works if I clear out
>>> the OBJCOPYFLAGS variable first but I don't think that's the correct way to
>>> fix this.
>>>
>>> Thanks,
>>> Laura
>>>
>>>
>>>> Signed-off-by: Kees Cook <keescook@chromium.org>
>>>> ---
>>>>  drivers/misc/Makefile       |  7 +++++++
>>>>  drivers/misc/lkdtm.h        |  6 ++++++
>>>>  drivers/misc/lkdtm_core.c   | 24 +++++++++++++++++-------
>>>>  drivers/misc/lkdtm_rodata.c | 10 ++++++++++
>>>>  4 files changed, 40 insertions(+), 7 deletions(-)
>>>>  create mode 100644 drivers/misc/lkdtm.h
>>>>  create mode 100644 drivers/misc/lkdtm_rodata.c
>>>>
>>>> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
>>>> index c3cb6ad8cc37..b2d3d68dfa22 100644
>>>> --- a/drivers/misc/Makefile
>>>> +++ b/drivers/misc/Makefile
>>>> @@ -59,3 +59,10 @@ obj-$(CONFIG_CXL_BASE)               += cxl/
>>>>  obj-$(CONFIG_PANEL)             += panel.o
>>>>
>>>>  lkdtm-$(CONFIG_LKDTM)          += lkdtm_core.o
>>>> +lkdtm-$(CONFIG_LKDTM)          += lkdtm_rodata_objcopy.o
>>>> +
>
> If I add:
>
> OBJCOPYFLAGS :=
>
> here, it seems to fix things...
>

I can confirm that this works on arm64

# echo EXEC_RODATA > /sys/kernel/debug/provoke-crash/DIRECT
[   21.725514] lkdtm: Performing direct entry EXEC_RODATA
[   21.725890] lkdtm: attempting ok execution at ffff0000084c0e08
[   21.726030] lkdtm: attempting bad execution at ffff000008880700
[   21.726401] Bad mode in Synchronous Abort handler detected on CPU2, code 0x8400000e -- IABT (current EL)
[   21.726847] CPU: 2 PID: 998 Comm: sh Not tainted 4.7.0-rc2+ #13

I wish the exception was clearer what the actual error was. I might propose a
patch to make it more obvious.

Thanks,
Laura

Re: Linker segfault on powerpc when CONFIG_LKDTM=y (was Re: [kernel-hardening] [PATCH 3/5] lkdtm: add function for testing .rodata section)

[Kees Cook]

On Mon, Aug 1, 2016 at 5:37 AM, Michael Ellerman <mpe@ellerman.id.au> wrote:
> Kees Cook <keescook@chromium.org> writes:
>
>> This adds a function that lives in the .rodata section. The section
>> flags are corrected using objcopy since there is no way with gcc to
>> declare section flags in an architecture-agnostic way.
>>
>> Signed-off-by: Kees Cook <keescook@chromium.org>
>> ---
>>  drivers/misc/Makefile       |  7 +++++++
>>  drivers/misc/lkdtm.h        |  6 ++++++
>>  drivers/misc/lkdtm_core.c   | 24 +++++++++++++++++-------
>>  drivers/misc/lkdtm_rodata.c | 10 ++++++++++
>>  4 files changed, 40 insertions(+), 7 deletions(-)
>>  create mode 100644 drivers/misc/lkdtm.h
>>  create mode 100644 drivers/misc/lkdtm_rodata.c
>
> This is blowing up my linker :(
>
>   scripts/link-vmlinux.sh: line 52: 36260 Segmentation fault      (core dumped) ${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2} -T ${lds} ${KBUILD_VMLINUX_INIT} --start-group ${KBUILD_VMLINUX_MAIN} --end-group ${1}
>
> Haven't had a chance to debug it further.

Argh. Do you want a quick fix for this now? I can add a PPC CONFIG
blacklist for the rodata check, maybe?

Also, what version of gcc? I'll see if I can reproduce this with a
cross compiler...

-Kees

-- 
Kees Cook
Chrome OS & Brillo Security

Re: [kernel-hardening] Re: Linker segfault on powerpc when CONFIG_LKDTM=y (was Re: [kernel-hardening] [PATCH 3/5] lkdtm: add function for testing .rodata section)

[Michael Ellerman]

Kees Cook <keescook@chromium.org> writes:

> On Mon, Aug 1, 2016 at 5:37 AM, Michael Ellerman <mpe@ellerman.id.au> wrote:
>> Kees Cook <keescook@chromium.org> writes:
>>
>>> This adds a function that lives in the .rodata section. The section
>>> flags are corrected using objcopy since there is no way with gcc to
>>> declare section flags in an architecture-agnostic way.
>>>
>>> Signed-off-by: Kees Cook <keescook@chromium.org>
>>> ---
>>>  drivers/misc/Makefile       |  7 +++++++
>>>  drivers/misc/lkdtm.h        |  6 ++++++
>>>  drivers/misc/lkdtm_core.c   | 24 +++++++++++++++++-------
>>>  drivers/misc/lkdtm_rodata.c | 10 ++++++++++
>>>  4 files changed, 40 insertions(+), 7 deletions(-)
>>>  create mode 100644 drivers/misc/lkdtm.h
>>>  create mode 100644 drivers/misc/lkdtm_rodata.c
>>
>> This is blowing up my linker :(
>>
>>   scripts/link-vmlinux.sh: line 52: 36260 Segmentation fault      (core dumped) ${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2} -T ${lds} ${KBUILD_VMLINUX_INIT} --start-group ${KBUILD_VMLINUX_MAIN} --end-group ${1}
>>
>> Haven't had a chance to debug it further.
>
> Argh. Do you want a quick fix for this now? I can add a PPC CONFIG
> blacklist for the rodata check, maybe?

Nah that's OK, none of our defconfigs have it enabled so it's not a real
blocker. It also builds OK as a module - though I haven't tested the
result yet.

> Also, what version of gcc? I'll see if I can reproduce this with a
> cross compiler...

The original hit was with gcc-5.3 (which is actually a x86->ppc cross):

  http://kisskb.ellerman.id.au/kisskb/buildresult/12762730/

But I can also reproduce with 5.4, and 6.1.0.

Interestingly I *can't* reproduce with the Ubuntu x86->ppc cross
(5.4.0-6ubuntu1~16.04.1).

Those toolchains are all using binutils 2.26 AFAIK.

Going back to a really old toolchain (gcc 4.6.3/binutils 2.22) it does
build but I get these warnings:

 powerpc64-linux-ld: drivers/misc/built-in.o: .opd is not a regular array of opd entries
 powerpc64-linux-ld: drivers/built-in.o: .opd is not a regular array of opd entries
 powerpc64-linux-ld: drivers/built-in.o: .opd is not a regular array of opd entries
 powerpc64-linux-ld: drivers/built-in.o: .opd is not a regular array of opd entries
 powerpc64-linux-ld: drivers/built-in.o: .opd is not a regular array of opd entries


So probably don't worry about it and we'll try and work it out on our end.

cheers

Re: [kernel-hardening] Re: Linker segfault on powerpc when CONFIG_LKDTM=y (was Re: [kernel-hardening] [PATCH 3/5] lkdtm: add function for testing .rodata section)

[Kees Cook]

On Mon, Aug 1, 2016 at 8:12 PM, Michael Ellerman <mpe@ellerman.id.au> wrote:
> Kees Cook <keescook@chromium.org> writes:
>
>> On Mon, Aug 1, 2016 at 5:37 AM, Michael Ellerman <mpe@ellerman.id.au> wrote:
>>> Kees Cook <keescook@chromium.org> writes:
>>>
>>>> This adds a function that lives in the .rodata section. The section
>>>> flags are corrected using objcopy since there is no way with gcc to
>>>> declare section flags in an architecture-agnostic way.
>>>>
>>>> Signed-off-by: Kees Cook <keescook@chromium.org>
>>>> ---
>>>>  drivers/misc/Makefile       |  7 +++++++
>>>>  drivers/misc/lkdtm.h        |  6 ++++++
>>>>  drivers/misc/lkdtm_core.c   | 24 +++++++++++++++++-------
>>>>  drivers/misc/lkdtm_rodata.c | 10 ++++++++++
>>>>  4 files changed, 40 insertions(+), 7 deletions(-)
>>>>  create mode 100644 drivers/misc/lkdtm.h
>>>>  create mode 100644 drivers/misc/lkdtm_rodata.c
>>>
>>> This is blowing up my linker :(
>>>
>>>   scripts/link-vmlinux.sh: line 52: 36260 Segmentation fault      (core dumped) ${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2} -T ${lds} ${KBUILD_VMLINUX_INIT} --start-group ${KBUILD_VMLINUX_MAIN} --end-group ${1}
>>>
>>> Haven't had a chance to debug it further.
>>
>> Argh. Do you want a quick fix for this now? I can add a PPC CONFIG
>> blacklist for the rodata check, maybe?
>
> Nah that's OK, none of our defconfigs have it enabled so it's not a real
> blocker. It also builds OK as a module - though I haven't tested the
> result yet.

Okay, I'll leave it as is.

>> Also, what version of gcc? I'll see if I can reproduce this with a
>> cross compiler...
>
> The original hit was with gcc-5.3 (which is actually a x86->ppc cross):
>
>   http://kisskb.ellerman.id.au/kisskb/buildresult/12762730/
>
> But I can also reproduce with 5.4, and 6.1.0.
>
> Interestingly I *can't* reproduce with the Ubuntu x86->ppc cross
> (5.4.0-6ubuntu1~16.04.1).

Oh, weird. Well, that does explains my lack of hitting the problem,
though: that's the cross compiler I was using. :P

> Those toolchains are all using binutils 2.26 AFAIK.

I wonder if this is some gold vs bfd issue, or a specific bug that got
fixed in the Ubuntu tree but hasn't landed in 6.1 or 5.4 (??)

> Going back to a really old toolchain (gcc 4.6.3/binutils 2.22) it does
> build but I get these warnings:
>
>  powerpc64-linux-ld: drivers/misc/built-in.o: .opd is not a regular array of opd entries
>  powerpc64-linux-ld: drivers/built-in.o: .opd is not a regular array of opd entries

How strange. I wonder if there's some corner case of the objcopy that
is wrong...

> So probably don't worry about it and we'll try and work it out on our end.

Okay, sounds good.

-Kees

-- 
Kees Cook
Chrome OS & Brillo Security

Re: [kernel-hardening] Re: Linker segfault on powerpc when CONFIG_LKDTM=y (was Re: [kernel-hardening] [PATCH 3/5] lkdtm: add function for testing .rodata section)

[Michael Ellerman]

Kees Cook <keescook@chromium.org> writes:
> On Mon, Aug 1, 2016 at 8:12 PM, Michael Ellerman <mpe@ellerman.id.au> wrote:
>> Kees Cook <keescook@chromium.org> writes:
>>> On Mon, Aug 1, 2016 at 5:37 AM, Michael Ellerman <mpe@ellerman.id.au> wrote:
>>>>
>>>>   scripts/link-vmlinux.sh: line 52: 36260 Segmentation fault      (core dumped) ${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2} -T ${lds} ${KBUILD_VMLINUX_INIT} --start-group ${KBUILD_VMLINUX_MAIN} --end-group ${1}
>>>>
>>>> Haven't had a chance to debug it further.
...
>> Interestingly I *can't* reproduce with the Ubuntu x86->ppc cross
>> (5.4.0-6ubuntu1~16.04.1).
>
> Oh, weird. Well, that does explains my lack of hitting the problem,
> though: that's the cross compiler I was using. :P

Actually that was a false negative.

The trick is you have to have LKDTM=y *and* FUNCTION_TRACER=y.

It is a linker bug:

  https://sourceware.org/bugzilla/show_bug.cgi?id=20428

Which Alan has already fixed.

But we need to workaround existing linkers that are out there.

We can do that by marking lkdtm_rodata_do_nothing() notrace, which I
think makes sense for all arches actually.

So I'll send you a patch to do that.

cheers

[PATCH 4/5] lkdtm: add usercopy tests

[Kees Cook]

This adds test to detect copy_to_user/copy_from_user problems that are
protected by PAX_USERCOPY (and will be protected by HARDENED_USERCOPY).
Explicitly tests both "to" and "from" directions of heap object size
problems, heap object markings and, stack frame misalignment.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/misc/lkdtm_core.c | 255 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 253 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
index 187cd9b63e9a..f212f865f9c6 100644
--- a/drivers/misc/lkdtm_core.c
+++ b/drivers/misc/lkdtm_core.c
@@ -111,7 +111,13 @@ enum ctype {
 	CT_WRITE_RO,
 	CT_WRITE_RO_AFTER_INIT,
 	CT_WRITE_KERN,
-	CT_WRAP_ATOMIC
+	CT_WRAP_ATOMIC,
+	CT_USERCOPY_HEAP_SIZE_TO,
+	CT_USERCOPY_HEAP_SIZE_FROM,
+	CT_USERCOPY_HEAP_FLAG_TO,
+	CT_USERCOPY_HEAP_FLAG_FROM,
+	CT_USERCOPY_STACK_FRAME_TO,
+	CT_USERCOPY_STACK_FRAME_FROM,
 };
 
 static char* cp_name[] = {
@@ -154,7 +160,13 @@ static char* cp_type[] = {
 	"WRITE_RO",
 	"WRITE_RO_AFTER_INIT",
 	"WRITE_KERN",
-	"WRAP_ATOMIC"
+	"WRAP_ATOMIC",
+	"USERCOPY_HEAP_SIZE_TO",
+	"USERCOPY_HEAP_SIZE_FROM",
+	"USERCOPY_HEAP_FLAG_TO",
+	"USERCOPY_HEAP_FLAG_FROM",
+	"USERCOPY_STACK_FRAME_TO",
+	"USERCOPY_STACK_FRAME_FROM",
 };
 
 static struct jprobe lkdtm;
@@ -166,6 +178,8 @@ static char* cpoint_name;
 static char* cpoint_type;
 static int cpoint_count = DEFAULT_COUNT;
 static int recur_count = REC_NUM_DEFAULT;
+static int alloc_size = 1024;
+static size_t cache_size;
 
 static enum cname cpoint = CN_INVALID;
 static enum ctype cptype = CT_NONE;
@@ -174,7 +188,9 @@ static DEFINE_SPINLOCK(count_lock);
 static DEFINE_SPINLOCK(lock_me_up);
 
 static u8 data_area[EXEC_SIZE];
+static struct kmem_cache *bad_cache;
 
+static const unsigned char test_text[] = "This is a test.\n";
 static const unsigned long rodata = 0xAA55AA55;
 static unsigned long ro_after_init __ro_after_init = 0x55AA5500;
 
@@ -188,6 +204,9 @@ MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\
 module_param(cpoint_count, int, 0644);
 MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\
 				"crash point is to be hit to trigger action");
+module_param(alloc_size, int, 0644);
+MODULE_PARM_DESC(alloc_size, " Size of allocation for user copy tests "\
+			     "(from 1 to PAGE_SIZE)");
 
 static unsigned int jp_do_irq(unsigned int irq)
 {
@@ -381,6 +400,213 @@ static void execute_user_location(void *dst)
 	func();
 }
 
+static noinline unsigned char *do_usercopy_stack_callee(int value)
+{
+	unsigned char buf[32];
+	unsigned char *ptr = NULL;
+	int i;
+
+	/* Exercise stack to avoid everything living in registers. */
+	for (i = 0; i < sizeof(buf); i++) {
+		/*
+		 * Hack to trick gcc into letting us return a reference
+		 * to a local stack frame.
+		 */
+		if (i == 0)
+			ptr = buf;
+		buf[i] = value & 0xff;
+	}
+
+	return ptr;
+}
+
+static noinline void do_usercopy_stack(bool to_user)
+{
+	unsigned long user_addr;
+	unsigned char good_stack[32];
+	unsigned char *bad_stack;
+	int i;
+
+	/* Exercise stack to avoid everything living in registers. */
+	for (i = 0; i < sizeof(good_stack); i++)
+		good_stack[i] = test_text[i % sizeof(test_text)];
+
+	/* This is a pointer to outside our current stack frame. */
+	bad_stack = do_usercopy_stack_callee(alloc_size);
+
+	user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
+			    PROT_READ | PROT_WRITE | PROT_EXEC,
+			    MAP_ANONYMOUS | MAP_PRIVATE, 0);
+	if (user_addr >= TASK_SIZE) {
+		pr_warn("Failed to allocate user memory\n");
+		return;
+	}
+
+	if (to_user) {
+		pr_info("attempting good copy_to_user of local stack\n");
+		if (copy_to_user((void __user *)user_addr, good_stack,
+				 sizeof(good_stack))) {
+			pr_warn("copy_to_user failed unexpectedly?!\n");
+			goto free_user;
+		}
+
+		pr_info("attempting bad copy_to_user of distant stack\n");
+		if (copy_to_user((void __user *)user_addr, bad_stack,
+				 sizeof(good_stack))) {
+			pr_warn("copy_to_user failed, but lacked Oops\n");
+			goto free_user;
+		}
+	} else {
+		pr_info("attempting good copy_from_user of local stack\n");
+		if (copy_from_user(good_stack, (void __user *)user_addr,
+				   sizeof(good_stack))) {
+			pr_warn("copy_from_user failed unexpectedly?!\n");
+			goto free_user;
+		}
+
+		pr_info("attempting bad copy_from_user of distant stack\n");
+		if (copy_from_user(bad_stack, (void __user *)user_addr,
+				   sizeof(good_stack))) {
+			pr_warn("copy_from_user failed, but lacked Oops\n");
+			goto free_user;
+		}
+	}
+
+free_user:
+	vm_munmap(user_addr, PAGE_SIZE);
+}
+
+static void do_usercopy_heap_size(bool to_user)
+{
+	unsigned long user_addr;
+	unsigned char *one, *two;
+	size_t size = clamp_t(int, alloc_size, 1, PAGE_SIZE);
+
+	one = kmalloc(size, GFP_KERNEL);
+	two = kmalloc(size, GFP_KERNEL);
+	if (!one || !two) {
+		pr_warn("Failed to allocate kernel memory\n");
+		goto free_kernel;
+	}
+
+	user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
+			    PROT_READ | PROT_WRITE | PROT_EXEC,
+			    MAP_ANONYMOUS | MAP_PRIVATE, 0);
+	if (user_addr >= TASK_SIZE) {
+		pr_warn("Failed to allocate user memory\n");
+		goto free_kernel;
+	}
+
+	memset(one, 'A', size);
+	memset(two, 'B', size);
+
+	if (to_user) {
+		pr_info("attempting good copy_to_user of correct size\n");
+		if (copy_to_user((void __user *)user_addr, one, size)) {
+			pr_warn("copy_to_user failed unexpectedly?!\n");
+			goto free_user;
+		}
+
+		pr_info("attempting bad copy_to_user of too large size\n");
+		if (copy_to_user((void __user *)user_addr, one, 2 * size)) {
+			pr_warn("copy_to_user failed, but lacked Oops\n");
+			goto free_user;
+		}
+	} else {
+		pr_info("attempting good copy_from_user of correct size\n");
+		if (copy_from_user(one, (void __user *)user_addr,
+				   size)) {
+			pr_warn("copy_from_user failed unexpectedly?!\n");
+			goto free_user;
+		}
+
+		pr_info("attempting bad copy_from_user of too large size\n");
+		if (copy_from_user(one, (void __user *)user_addr, 2 * size)) {
+			pr_warn("copy_from_user failed, but lacked Oops\n");
+			goto free_user;
+		}
+	}
+
+free_user:
+	vm_munmap(user_addr, PAGE_SIZE);
+free_kernel:
+	kfree(one);
+	kfree(two);
+}
+
+static void do_usercopy_heap_flag(bool to_user)
+{
+	unsigned long user_addr;
+	unsigned char *good_buf = NULL;
+	unsigned char *bad_buf = NULL;
+
+	/* Make sure cache was prepared. */
+	if (!bad_cache) {
+		pr_warn("Failed to allocate kernel cache\n");
+		return;
+	}
+
+	/*
+	 * Allocate one buffer from each cache (kmalloc will have the
+	 * SLAB_USERCOPY flag already, but "bad_cache" won't).
+	 */
+	good_buf = kmalloc(cache_size, GFP_KERNEL);
+	bad_buf = kmem_cache_alloc(bad_cache, GFP_KERNEL);
+	if (!good_buf || !bad_buf) {
+		pr_warn("Failed to allocate buffers from caches\n");
+		goto free_alloc;
+	}
+
+	/* Allocate user memory we'll poke at. */
+	user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
+			    PROT_READ | PROT_WRITE | PROT_EXEC,
+			    MAP_ANONYMOUS | MAP_PRIVATE, 0);
+	if (user_addr >= TASK_SIZE) {
+		pr_warn("Failed to allocate user memory\n");
+		goto free_alloc;
+	}
+
+	memset(good_buf, 'A', cache_size);
+	memset(bad_buf, 'B', cache_size);
+
+	if (to_user) {
+		pr_info("attempting good copy_to_user with SLAB_USERCOPY\n");
+		if (copy_to_user((void __user *)user_addr, good_buf,
+				 cache_size)) {
+			pr_warn("copy_to_user failed unexpectedly?!\n");
+			goto free_user;
+		}
+
+		pr_info("attempting bad copy_to_user w/o SLAB_USERCOPY\n");
+		if (copy_to_user((void __user *)user_addr, bad_buf,
+				 cache_size)) {
+			pr_warn("copy_to_user failed, but lacked Oops\n");
+			goto free_user;
+		}
+	} else {
+		pr_info("attempting good copy_from_user with SLAB_USERCOPY\n");
+		if (copy_from_user(good_buf, (void __user *)user_addr,
+				   cache_size)) {
+			pr_warn("copy_from_user failed unexpectedly?!\n");
+			goto free_user;
+		}
+
+		pr_info("attempting bad copy_from_user w/o SLAB_USERCOPY\n");
+		if (copy_from_user(bad_buf, (void __user *)user_addr,
+				   cache_size)) {
+			pr_warn("copy_from_user failed, but lacked Oops\n");
+			goto free_user;
+		}
+	}
+
+free_user:
+	vm_munmap(user_addr, PAGE_SIZE);
+free_alloc:
+	if (bad_buf)
+		kmem_cache_free(bad_cache, bad_buf);
+	kfree(good_buf);
+}
+
 static void lkdtm_do_action(enum ctype which)
 {
 	switch (which) {
@@ -679,6 +905,24 @@ static void lkdtm_do_action(enum ctype which)
 
 		return;
 	}
+	case CT_USERCOPY_HEAP_SIZE_TO:
+		do_usercopy_heap_size(true);
+		break;
+	case CT_USERCOPY_HEAP_SIZE_FROM:
+		do_usercopy_heap_size(false);
+		break;
+	case CT_USERCOPY_HEAP_FLAG_TO:
+		do_usercopy_heap_flag(true);
+		break;
+	case CT_USERCOPY_HEAP_FLAG_FROM:
+		do_usercopy_heap_flag(false);
+		break;
+	case CT_USERCOPY_STACK_FRAME_TO:
+		do_usercopy_stack(true);
+		break;
+	case CT_USERCOPY_STACK_FRAME_FROM:
+		do_usercopy_stack(false);
+		break;
 	case CT_NONE:
 	default:
 		break;
@@ -971,6 +1215,11 @@ static int __init lkdtm_module_init(void)
 	/* Make sure we can write to __ro_after_init values during __init */
 	ro_after_init |= 0xAA;
 
+	/* Prepare cache that lacks SLAB_USERCOPY flag. */
+	cache_size = clamp_t(int, alloc_size, 1, PAGE_SIZE);
+	bad_cache = kmem_cache_create("lkdtm-no-usercopy", cache_size, 0,
+				      0, NULL);
+
 	/* Register debugfs interface */
 	lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
 	if (!lkdtm_debugfs_root) {
@@ -1022,6 +1271,8 @@ static void __exit lkdtm_module_exit(void)
 {
 	debugfs_remove_recursive(lkdtm_debugfs_root);
 
+	kmem_cache_destroy(bad_cache);
+
 	unregister_jprobe(&lkdtm);
 	pr_info("Crash point unregistered\n");
 }
-- 
2.7.4

Re: [PATCH 4/5] lkdtm: add usercopy tests

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1914 bytes --]

Hi,

[auto build test WARNING on char-misc/char-misc-testing]
[also build test WARNING on v4.7-rc2 next-20160607]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Kees-Cook/lkdtm-add-usercopy-and-rodata-fix-atomic/20160608-060444
config: s390-default_defconfig (attached as .config)
compiler: s390x-linux-gnu-gcc (Debian 5.3.1-8) 5.3.1 20160205
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=s390 

All warnings (new ones prefixed by >>):

   drivers/misc/lkdtm_core.c: In function 'do_usercopy_stack_callee.isra.0':
>> drivers/misc/lkdtm_core.c:420:9: warning: function returns address of local variable [-Wreturn-local-addr]
     return ptr;
            ^
   drivers/misc/lkdtm_core.c:405:16: note: declared here
     unsigned char buf[32];
                   ^

vim +420 drivers/misc/lkdtm_core.c

   404	{
   405		unsigned char buf[32];
   406		unsigned char *ptr = NULL;
   407		int i;
   408	
   409		/* Exercise stack to avoid everything living in registers. */
   410		for (i = 0; i < sizeof(buf); i++) {
   411			/*
   412			 * Hack to trick gcc into letting us return a reference
   413			 * to a local stack frame.
   414			 */
   415			if (i == 0)
   416				ptr = buf;
   417			buf[i] = value & 0xff;
   418		}
   419	
 > 420		return ptr;
   421	}
   422	
   423	static noinline void do_usercopy_stack(bool to_user)
   424	{
   425		unsigned long user_addr;
   426		unsigned char good_stack[32];
   427		unsigned char *bad_stack;
   428		int i;

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/octet-stream, Size: 16142 bytes --]

Re: [PATCH 4/5] lkdtm: add usercopy tests

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1751 bytes --]

Hi,

[auto build test WARNING on char-misc/char-misc-testing]
[also build test WARNING on v4.7-rc2 next-20160607]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Kees-Cook/lkdtm-add-usercopy-and-rodata-fix-atomic/20160608-060444
config: x86_64-randconfig-s2-06080621 (attached as .config)
compiler: gcc-6 (Debian 6.1.1-1) 6.1.1 20160430
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All warnings (new ones prefixed by >>):

   drivers/misc/lkdtm_core.c: In function 'do_usercopy_stack_callee':
>> drivers/misc/lkdtm_core.c:420:9: warning: function may return address of local variable [-Wreturn-local-addr]
     return ptr;
            ^~~
   drivers/misc/lkdtm_core.c:405:16: note: declared here
     unsigned char buf[32];
                   ^~~

vim +420 drivers/misc/lkdtm_core.c

   404	{
   405		unsigned char buf[32];
   406		unsigned char *ptr = NULL;
   407		int i;
   408	
   409		/* Exercise stack to avoid everything living in registers. */
   410		for (i = 0; i < sizeof(buf); i++) {
   411			/*
   412			 * Hack to trick gcc into letting us return a reference
   413			 * to a local stack frame.
   414			 */
   415			if (i == 0)
   416				ptr = buf;
   417			buf[i] = value & 0xff;
   418		}
   419	
 > 420		return ptr;
   421	}
   422	
   423	static noinline void do_usercopy_stack(bool to_user)
   424	{
   425		unsigned long user_addr;
   426		unsigned char good_stack[32];
   427		unsigned char *bad_stack;
   428		int i;

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/octet-stream, Size: 26281 bytes --]

[PATCH 5/5] lkdtm: split atomic test into over and underflow

[Kees Cook]

Each direction of the atomic wrapping should be individually testable.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/misc/lkdtm_core.c | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
index f212f865f9c6..b5a544f2b645 100644
--- a/drivers/misc/lkdtm_core.c
+++ b/drivers/misc/lkdtm_core.c
@@ -111,7 +111,8 @@ enum ctype {
 	CT_WRITE_RO,
 	CT_WRITE_RO_AFTER_INIT,
 	CT_WRITE_KERN,
-	CT_WRAP_ATOMIC,
+	CT_ATOMIC_UNDERFLOW,
+	CT_ATOMIC_OVERFLOW,
 	CT_USERCOPY_HEAP_SIZE_TO,
 	CT_USERCOPY_HEAP_SIZE_FROM,
 	CT_USERCOPY_HEAP_FLAG_TO,
@@ -160,7 +161,8 @@ static char* cp_type[] = {
 	"WRITE_RO",
 	"WRITE_RO_AFTER_INIT",
 	"WRITE_KERN",
-	"WRAP_ATOMIC",
+	"ATOMIC_UNDERFLOW",
+	"ATOMIC_OVERFLOW",
 	"USERCOPY_HEAP_SIZE_TO",
 	"USERCOPY_HEAP_SIZE_FROM",
 	"USERCOPY_HEAP_FLAG_TO",
@@ -894,13 +896,25 @@ static void lkdtm_do_action(enum ctype which)
 		do_overwritten();
 		break;
 	}
-	case CT_WRAP_ATOMIC: {
+	case CT_ATOMIC_UNDERFLOW: {
 		atomic_t under = ATOMIC_INIT(INT_MIN);
-		atomic_t over = ATOMIC_INIT(INT_MAX);
 
-		pr_info("attempting atomic underflow\n");
+		pr_info("attempting good atomic increment\n");
+		atomic_inc(&under);
+		atomic_dec(&under);
+
+		pr_info("attempting bad atomic underflow\n");
 		atomic_dec(&under);
-		pr_info("attempting atomic overflow\n");
+		break;
+	}
+	case CT_ATOMIC_OVERFLOW: {
+		atomic_t over = ATOMIC_INIT(INT_MAX);
+
+		pr_info("attempting good atomic decrement\n");
+		atomic_dec(&over);
+		atomic_inc(&over);
+
+		pr_info("attempting bad atomic overflow\n");
 		atomic_inc(&over);
 
 		return;
-- 
2.7.4