[linux-2.6-block.git] / drivers / misc / lkdtm_usercopy.c

// SPDX-License-Identifier: GPL-2.0
/*
 * This is for all the tests related to copy_to_user() and copy_from_user()
 * hardening.
 */
#include "lkdtm.h"
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/sched/task_stack.h>
#include <linux/mman.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>

/*
 * Many of the tests here end up using const sizes, but those would
 * normally be ignored by hardened usercopy, so force the compiler
 * into choosing the non-const path to make sure we trigger the
 * hardened usercopy checks by added "unconst" to all the const copies,
 * and making sure "cache_size" isn't optimized into a const.
 */
static volatile size_t unconst = 0;
static volatile size_t cache_size = 1024;
static struct kmem_cache *whitelist_cache;

static const unsigned char test_text[] = "This is a test.\n";

/*
 * Instead of adding -Wno-return-local-addr, just pass the stack address
 * through a function to obfuscate it from the compiler.
 */
static noinline unsigned char *trick_compiler(unsigned char *stack)
{
	return stack + 0;
}

static noinline unsigned char *do_usercopy_stack_callee(int value)
{
	unsigned char buf[32];
	int i;

	/* Exercise stack to avoid everything living in registers. */
	for (i = 0; i < sizeof(buf); i++) {
		buf[i] = value & 0xff;
	}

	return trick_compiler(buf);
}

static noinline void do_usercopy_stack(bool to_user, bool bad_frame)
{
	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. */
	if (bad_frame) {
		bad_stack = do_usercopy_stack_callee((uintptr_t)&bad_stack);
	} else {
		/* Put start address just inside stack. */
		bad_stack = task_stack_page(current) + THREAD_SIZE;
		bad_stack -= sizeof(unsigned long);
	}

	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,
				 unconst + 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,
				 unconst + sizeof(good_stack))) {
			pr_warn("copy_to_user failed, but lacked Oops\n");
			goto free_user;
		}
	} else {
		/*
		 * There isn't a safe way to not be protected by usercopy
		 * if we're going to write to another thread's stack.
		 */
		if (!bad_frame)
			goto free_user;

		pr_info("attempting good copy_from_user of local stack\n");
		if (copy_from_user(good_stack, (void __user *)user_addr,
				   unconst + 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,
				   unconst + sizeof(good_stack))) {
			pr_warn("copy_from_user failed, but lacked Oops\n");
			goto free_user;
		}
	}

free_user:
	vm_munmap(user_addr, PAGE_SIZE);
}

/*
 * This checks for whole-object size validation with hardened usercopy,
 * with or without usercopy whitelisting.
 */
static void do_usercopy_heap_size(bool to_user)
{
	unsigned long user_addr;
	unsigned char *one, *two;
	void __user *test_user_addr;
	void *test_kern_addr;
	size_t size = unconst + 1024;

	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);

	test_user_addr = (void __user *)(user_addr + 16);
	test_kern_addr = one + 16;

	if (to_user) {
		pr_info("attempting good copy_to_user of correct size\n");
		if (copy_to_user(test_user_addr, test_kern_addr, size / 2)) {
			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(test_user_addr, test_kern_addr, 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(test_kern_addr, test_user_addr, size / 2)) {
			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(test_kern_addr, test_user_addr, 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);
}

/*
 * This checks for the specific whitelist window within an object. If this
 * test passes, then do_usercopy_heap_size() tests will pass too.
 */
static void do_usercopy_heap_whitelist(bool to_user)
{
	unsigned long user_alloc;
	unsigned char *buf = NULL;
	unsigned char __user *user_addr;
	size_t offset, size;

	/* Make sure cache was prepared. */
	if (!whitelist_cache) {
		pr_warn("Failed to allocate kernel cache\n");
		return;
	}

	/*
	 * Allocate a buffer with a whitelisted window in the buffer.
	 */
	buf = kmem_cache_alloc(whitelist_cache, GFP_KERNEL);
	if (!buf) {
		pr_warn("Failed to allocate buffer from whitelist cache\n");
		goto free_alloc;
	}

	/* Allocate user memory we'll poke at. */
	user_alloc = vm_mmap(NULL, 0, PAGE_SIZE,
			    PROT_READ | PROT_WRITE | PROT_EXEC,
			    MAP_ANONYMOUS | MAP_PRIVATE, 0);
	if (user_alloc >= TASK_SIZE) {
		pr_warn("Failed to allocate user memory\n");
		goto free_alloc;
	}
	user_addr = (void __user *)user_alloc;

	memset(buf, 'B', cache_size);

	/* Whitelisted window in buffer, from kmem_cache_create_usercopy. */
	offset = (cache_size / 4) + unconst;
	size = (cache_size / 16) + unconst;

	if (to_user) {
		pr_info("attempting good copy_to_user inside whitelist\n");
		if (copy_to_user(user_addr, buf + offset, size)) {
			pr_warn("copy_to_user failed unexpectedly?!\n");
			goto free_user;
		}

		pr_info("attempting bad copy_to_user outside whitelist\n");
		if (copy_to_user(user_addr, buf + offset - 1, size)) {
			pr_warn("copy_to_user failed, but lacked Oops\n");
			goto free_user;
		}
	} else {
		pr_info("attempting good copy_from_user inside whitelist\n");
		if (copy_from_user(buf + offset, user_addr, size)) {
			pr_warn("copy_from_user failed unexpectedly?!\n");
			goto free_user;
		}

		pr_info("attempting bad copy_from_user outside whitelist\n");
		if (copy_from_user(buf + offset - 1, user_addr, size)) {
			pr_warn("copy_from_user failed, but lacked Oops\n");
			goto free_user;
		}
	}

free_user:
	vm_munmap(user_alloc, PAGE_SIZE);
free_alloc:
	if (buf)
		kmem_cache_free(whitelist_cache, buf);
}

/* Callable tests. */
void lkdtm_USERCOPY_HEAP_SIZE_TO(void)
{
	do_usercopy_heap_size(true);
}

void lkdtm_USERCOPY_HEAP_SIZE_FROM(void)
{
	do_usercopy_heap_size(false);
}

void lkdtm_USERCOPY_HEAP_WHITELIST_TO(void)
{
	do_usercopy_heap_whitelist(true);
}

void lkdtm_USERCOPY_HEAP_WHITELIST_FROM(void)
{
	do_usercopy_heap_whitelist(false);
}

void lkdtm_USERCOPY_STACK_FRAME_TO(void)
{
	do_usercopy_stack(true, true);
}

void lkdtm_USERCOPY_STACK_FRAME_FROM(void)
{
	do_usercopy_stack(false, true);
}

void lkdtm_USERCOPY_STACK_BEYOND(void)
{
	do_usercopy_stack(true, false);
}

void lkdtm_USERCOPY_KERNEL(void)
{
	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;
	}

	pr_info("attempting good copy_to_user from kernel rodata\n");
	if (copy_to_user((void __user *)user_addr, test_text,
			 unconst + sizeof(test_text))) {
		pr_warn("copy_to_user failed unexpectedly?!\n");
		goto free_user;
	}

	pr_info("attempting bad copy_to_user from kernel text\n");
	if (copy_to_user((void __user *)user_addr, vm_mmap,
			 unconst + PAGE_SIZE)) {
		pr_warn("copy_to_user failed, but lacked Oops\n");
		goto free_user;
	}

free_user:
	vm_munmap(user_addr, PAGE_SIZE);
}

void __init lkdtm_usercopy_init(void)
{
	/* Prepare cache that lacks SLAB_USERCOPY flag. */
	whitelist_cache =
		kmem_cache_create_usercopy("lkdtm-usercopy", cache_size,
					   0, 0,
					   cache_size / 4,
					   cache_size / 16,
					   NULL);
}

void __exit lkdtm_usercopy_exit(void)
{
	kmem_cache_destroy(whitelist_cache);
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
a3dff71c KC	2	/*
	3	* This is for all the tests related to copy_to_user() and copy_from_user()
	4	* hardening.
	5	*/
6d2e91a6	6	#include "lkdtm.h"
a3dff71c KC	7	#include <linux/slab.h>
a3dff71c KC	8	#include <linux/vmalloc.h>
68db0cf1	9	#include <linux/sched/task_stack.h>
a3dff71c KC	10	#include <linux/mman.h>
	11	#include <linux/uaccess.h>
	12	#include <asm/cacheflush.h>
	13
3c17648c KC	14	/*
	15	* Many of the tests here end up using const sizes, but those would
	16	* normally be ignored by hardened usercopy, so force the compiler
	17	* into choosing the non-const path to make sure we trigger the
	18	* hardened usercopy checks by added "unconst" to all the const copies,
	19	* and making sure "cache_size" isn't optimized into a const.
	20	*/
	21	static volatile size_t unconst = 0;
	22	static volatile size_t cache_size = 1024;
e47e3118	23	static struct kmem_cache *whitelist_cache;
a3dff71c KC	24
	25	static const unsigned char test_text[] = "This is a test.\n";
	26
	27	/*
	28	* Instead of adding -Wno-return-local-addr, just pass the stack address
	29	* through a function to obfuscate it from the compiler.
	30	*/
	31	static noinline unsigned char trick_compiler(unsigned char stack)
	32	{
	33	return stack + 0;
	34	}
	35
	36	static noinline unsigned char *do_usercopy_stack_callee(int value)
	37	{
	38	unsigned char buf[32];
	39	int i;
	40
	41	/* Exercise stack to avoid everything living in registers. */
	42	for (i = 0; i < sizeof(buf); i++) {
	43	buf[i] = value & 0xff;
	44	}
	45
	46	return trick_compiler(buf);
	47	}
	48
	49	static noinline void do_usercopy_stack(bool to_user, bool bad_frame)
	50	{
	51	unsigned long user_addr;
	52	unsigned char good_stack[32];
	53	unsigned char *bad_stack;
	54	int i;
	55
	56	/* Exercise stack to avoid everything living in registers. */
	57	for (i = 0; i < sizeof(good_stack); i++)
	58	good_stack[i] = test_text[i % sizeof(test_text)];
	59
	60	/* This is a pointer to outside our current stack frame. */
	61	if (bad_frame) {
30010874	62	bad_stack = do_usercopy_stack_callee((uintptr_t)&bad_stack);
a3dff71c KC	63	} else {
	64	/* Put start address just inside stack. */
	65	bad_stack = task_stack_page(current) + THREAD_SIZE;
	66	bad_stack -= sizeof(unsigned long);
	67	}
	68
	69	user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
	70	PROT_READ \| PROT_WRITE \| PROT_EXEC,
	71	MAP_ANONYMOUS \| MAP_PRIVATE, 0);
	72	if (user_addr >= TASK_SIZE) {
	73	pr_warn("Failed to allocate user memory\n");
	74	return;
	75	}
	76
	77	if (to_user) {
	78	pr_info("attempting good copy_to_user of local stack\n");
	79	if (copy_to_user((void __user *)user_addr, good_stack,
3c17648c	80	unconst + sizeof(good_stack))) {
a3dff71c KC	81	pr_warn("copy_to_user failed unexpectedly?!\n");
	82	goto free_user;
	83	}
	84
	85	pr_info("attempting bad copy_to_user of distant stack\n");
	86	if (copy_to_user((void __user *)user_addr, bad_stack,
3c17648c	87	unconst + sizeof(good_stack))) {
a3dff71c KC	88	pr_warn("copy_to_user failed, but lacked Oops\n");
	89	goto free_user;
	90	}
	91	} else {
	92	/*
	93	* There isn't a safe way to not be protected by usercopy
	94	* if we're going to write to another thread's stack.
	95	*/
	96	if (!bad_frame)
	97	goto free_user;
	98
	99	pr_info("attempting good copy_from_user of local stack\n");
	100	if (copy_from_user(good_stack, (void __user *)user_addr,
3c17648c	101	unconst + sizeof(good_stack))) {
a3dff71c KC	102	pr_warn("copy_from_user failed unexpectedly?!\n");
	103	goto free_user;
	104	}
	105
	106	pr_info("attempting bad copy_from_user of distant stack\n");
	107	if (copy_from_user(bad_stack, (void __user *)user_addr,
3c17648c	108	unconst + sizeof(good_stack))) {
a3dff71c KC	109	pr_warn("copy_from_user failed, but lacked Oops\n");
	110	goto free_user;
	111	}
	112	}
	113
	114	free_user:
	115	vm_munmap(user_addr, PAGE_SIZE);
	116	}
	117
e47e3118 KC	118	/*
	119	* This checks for whole-object size validation with hardened usercopy,
	120	* with or without usercopy whitelisting.
	121	*/
a3dff71c KC	122	static void do_usercopy_heap_size(bool to_user)
	123	{
	124	unsigned long user_addr;
	125	unsigned char one, two;
c7588686 KC	126	void __user *test_user_addr;
c7588686 KC	127	void *test_kern_addr;
3c17648c	128	size_t size = unconst + 1024;
a3dff71c KC	129
	130	one = kmalloc(size, GFP_KERNEL);
	131	two = kmalloc(size, GFP_KERNEL);
	132	if (!one \|\| !two) {
	133	pr_warn("Failed to allocate kernel memory\n");
	134	goto free_kernel;
	135	}
	136
	137	user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
	138	PROT_READ \| PROT_WRITE \| PROT_EXEC,
	139	MAP_ANONYMOUS \| MAP_PRIVATE, 0);
	140	if (user_addr >= TASK_SIZE) {
	141	pr_warn("Failed to allocate user memory\n");
	142	goto free_kernel;
	143	}
	144
	145	memset(one, 'A', size);
	146	memset(two, 'B', size);
	147
c7588686 KC	148	test_user_addr = (void __user *)(user_addr + 16);
	149	test_kern_addr = one + 16;
	150
a3dff71c KC	151	if (to_user) {
a3dff71c KC	152	pr_info("attempting good copy_to_user of correct size\n");
c7588686	153	if (copy_to_user(test_user_addr, test_kern_addr, size / 2)) {
a3dff71c KC	154	pr_warn("copy_to_user failed unexpectedly?!\n");
	155	goto free_user;
	156	}
	157
	158	pr_info("attempting bad copy_to_user of too large size\n");
c7588686	159	if (copy_to_user(test_user_addr, test_kern_addr, size)) {
a3dff71c KC	160	pr_warn("copy_to_user failed, but lacked Oops\n");
	161	goto free_user;
	162	}
	163	} else {
	164	pr_info("attempting good copy_from_user of correct size\n");
c7588686	165	if (copy_from_user(test_kern_addr, test_user_addr, size / 2)) {
a3dff71c KC	166	pr_warn("copy_from_user failed unexpectedly?!\n");
	167	goto free_user;
	168	}
	169
	170	pr_info("attempting bad copy_from_user of too large size\n");
c7588686	171	if (copy_from_user(test_kern_addr, test_user_addr, size)) {
a3dff71c KC	172	pr_warn("copy_from_user failed, but lacked Oops\n");
	173	goto free_user;
	174	}
	175	}
	176
	177	free_user:
	178	vm_munmap(user_addr, PAGE_SIZE);
	179	free_kernel:
	180	kfree(one);
	181	kfree(two);
	182	}
	183
e47e3118 KC	184	/*
	185	* This checks for the specific whitelist window within an object. If this
	186	* test passes, then do_usercopy_heap_size() tests will pass too.
	187	*/
	188	static void do_usercopy_heap_whitelist(bool to_user)
a3dff71c	189	{
e47e3118 KC	190	unsigned long user_alloc;
	191	unsigned char *buf = NULL;
	192	unsigned char __user *user_addr;
	193	size_t offset, size;
a3dff71c KC	194
a3dff71c KC	195	/* Make sure cache was prepared. */
e47e3118	196	if (!whitelist_cache) {
a3dff71c KC	197	pr_warn("Failed to allocate kernel cache\n");
	198	return;
	199	}
	200
	201	/*
e47e3118	202	* Allocate a buffer with a whitelisted window in the buffer.
a3dff71c	203	*/
e47e3118 KC	204	buf = kmem_cache_alloc(whitelist_cache, GFP_KERNEL);
	205	if (!buf) {
	206	pr_warn("Failed to allocate buffer from whitelist cache\n");
a3dff71c KC	207	goto free_alloc;
	208	}
	209
	210	/* Allocate user memory we'll poke at. */
e47e3118	211	user_alloc = vm_mmap(NULL, 0, PAGE_SIZE,
a3dff71c KC	212	PROT_READ \| PROT_WRITE \| PROT_EXEC,
a3dff71c KC	213	MAP_ANONYMOUS \| MAP_PRIVATE, 0);
e47e3118	214	if (user_alloc >= TASK_SIZE) {
a3dff71c KC	215	pr_warn("Failed to allocate user memory\n");
	216	goto free_alloc;
	217	}
e47e3118	218	user_addr = (void __user *)user_alloc;
a3dff71c	219
e47e3118 KC	220	memset(buf, 'B', cache_size);
	221
	222	/* Whitelisted window in buffer, from kmem_cache_create_usercopy. */
	223	offset = (cache_size / 4) + unconst;
	224	size = (cache_size / 16) + unconst;
a3dff71c KC	225
a3dff71c KC	226	if (to_user) {
e47e3118 KC	227	pr_info("attempting good copy_to_user inside whitelist\n");
e47e3118 KC	228	if (copy_to_user(user_addr, buf + offset, size)) {
a3dff71c KC	229	pr_warn("copy_to_user failed unexpectedly?!\n");
	230	goto free_user;
	231	}
	232
e47e3118 KC	233	pr_info("attempting bad copy_to_user outside whitelist\n");
e47e3118 KC	234	if (copy_to_user(user_addr, buf + offset - 1, size)) {
a3dff71c KC	235	pr_warn("copy_to_user failed, but lacked Oops\n");
	236	goto free_user;
	237	}
	238	} else {
e47e3118 KC	239	pr_info("attempting good copy_from_user inside whitelist\n");
e47e3118 KC	240	if (copy_from_user(buf + offset, user_addr, size)) {
a3dff71c KC	241	pr_warn("copy_from_user failed unexpectedly?!\n");
	242	goto free_user;
	243	}
	244
e47e3118 KC	245	pr_info("attempting bad copy_from_user outside whitelist\n");
e47e3118 KC	246	if (copy_from_user(buf + offset - 1, user_addr, size)) {
a3dff71c KC	247	pr_warn("copy_from_user failed, but lacked Oops\n");
	248	goto free_user;
	249	}
	250	}
	251
	252	free_user:
e47e3118	253	vm_munmap(user_alloc, PAGE_SIZE);
a3dff71c	254	free_alloc:
e47e3118 KC	255	if (buf)
e47e3118 KC	256	kmem_cache_free(whitelist_cache, buf);
a3dff71c KC	257	}
	258
	259	/* Callable tests. */
	260	void lkdtm_USERCOPY_HEAP_SIZE_TO(void)
	261	{
	262	do_usercopy_heap_size(true);
	263	}
	264
	265	void lkdtm_USERCOPY_HEAP_SIZE_FROM(void)
	266	{
	267	do_usercopy_heap_size(false);
	268	}
	269
e47e3118	270	void lkdtm_USERCOPY_HEAP_WHITELIST_TO(void)
a3dff71c	271	{
e47e3118	272	do_usercopy_heap_whitelist(true);
a3dff71c KC	273	}
a3dff71c KC	274
e47e3118	275	void lkdtm_USERCOPY_HEAP_WHITELIST_FROM(void)
a3dff71c	276	{
e47e3118	277	do_usercopy_heap_whitelist(false);
a3dff71c KC	278	}
	279
	280	void lkdtm_USERCOPY_STACK_FRAME_TO(void)
	281	{
	282	do_usercopy_stack(true, true);
	283	}
	284
	285	void lkdtm_USERCOPY_STACK_FRAME_FROM(void)
	286	{
	287	do_usercopy_stack(false, true);
	288	}
	289
	290	void lkdtm_USERCOPY_STACK_BEYOND(void)
	291	{
	292	do_usercopy_stack(true, false);
	293	}
	294
	295	void lkdtm_USERCOPY_KERNEL(void)
	296	{
	297	unsigned long user_addr;
	298
	299	user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
	300	PROT_READ \| PROT_WRITE \| PROT_EXEC,
	301	MAP_ANONYMOUS \| MAP_PRIVATE, 0);
	302	if (user_addr >= TASK_SIZE) {
	303	pr_warn("Failed to allocate user memory\n");
	304	return;
	305	}
	306
	307	pr_info("attempting good copy_to_user from kernel rodata\n");
	308	if (copy_to_user((void __user *)user_addr, test_text,
3c17648c	309	unconst + sizeof(test_text))) {
a3dff71c KC	310	pr_warn("copy_to_user failed unexpectedly?!\n");
	311	goto free_user;
	312	}
	313
	314	pr_info("attempting bad copy_to_user from kernel text\n");
3c17648c KC	315	if (copy_to_user((void __user *)user_addr, vm_mmap,
3c17648c KC	316	unconst + PAGE_SIZE)) {
a3dff71c KC	317	pr_warn("copy_to_user failed, but lacked Oops\n");
	318	goto free_user;
	319	}
	320
	321	free_user:
	322	vm_munmap(user_addr, PAGE_SIZE);
	323	}
	324
	325	void __init lkdtm_usercopy_init(void)
	326	{
	327	/* Prepare cache that lacks SLAB_USERCOPY flag. */
e47e3118 KC	328	whitelist_cache =
	329	kmem_cache_create_usercopy("lkdtm-usercopy", cache_size,
	330	0, 0,
	331	cache_size / 4,
	332	cache_size / 16,
	333	NULL);
a3dff71c KC	334	}
	335
	336	void __exit lkdtm_usercopy_exit(void)
	337	{
e47e3118	338	kmem_cache_destroy(whitelist_cache);
a3dff71c	339	}