[linux-2.6-block.git] / lib / test_user_copy.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Kernel module for testing copy_to/from_user infrastructure.
 *
 * Copyright 2013 Google Inc. All Rights Reserved
 *
 * Authors:
 *      Kees Cook       <keescook@chromium.org>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/mman.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/vmalloc.h>

/*
 * Several 32-bit architectures support 64-bit {get,put}_user() calls.
 * As there doesn't appear to be anything that can safely determine
 * their capability at compile-time, we just have to opt-out certain archs.
 */
#if BITS_PER_LONG == 64 || (!(defined(CONFIG_ARM) && !defined(MMU)) && \
			    !defined(CONFIG_M68K) &&		\
			    !defined(CONFIG_MICROBLAZE) &&	\
			    !defined(CONFIG_NIOS2) &&		\
			    !defined(CONFIG_PPC32) &&		\
			    !defined(CONFIG_SUPERH))
# define TEST_U64
#endif

#define test(condition, msg, ...)					\
({									\
	int cond = (condition);						\
	if (cond)							\
		pr_warn("[%d] " msg "\n", __LINE__, ##__VA_ARGS__);	\
	cond;								\
})

static bool is_zeroed(void *from, size_t size)
{
	return memchr_inv(from, 0x0, size) == NULL;
}

static int test_check_nonzero_user(char *kmem, char __user *umem, size_t size)
{
	int ret = 0;
	size_t start, end, i;
	size_t zero_start = size / 4;
	size_t zero_end = size - zero_start;

	/*
	 * We conduct a series of check_nonzero_user() tests on a block of memory
	 * with the following byte-pattern (trying every possible [start,end]
	 * pair):
	 *
	 *   [ 00 ff 00 ff ... 00 00 00 00 ... ff 00 ff 00 ]
	 *
	 * And we verify that check_nonzero_user() acts identically to memchr_inv().
	 */

	memset(kmem, 0x0, size);
	for (i = 1; i < zero_start; i += 2)
		kmem[i] = 0xff;
	for (i = zero_end; i < size; i += 2)
		kmem[i] = 0xff;

	ret |= test(copy_to_user(umem, kmem, size),
		    "legitimate copy_to_user failed");

	for (start = 0; start <= size; start++) {
		for (end = start; end <= size; end++) {
			size_t len = end - start;
			int retval = check_zeroed_user(umem + start, len);
			int expected = is_zeroed(kmem + start, len);

			ret |= test(retval != expected,
				    "check_nonzero_user(=%d) != memchr_inv(=%d) mismatch (start=%zu, end=%zu)",
				    retval, expected, start, end);
		}
	}

	return ret;
}

static int test_copy_struct_from_user(char *kmem, char __user *umem,
				      size_t size)
{
	int ret = 0;
	char *umem_src = NULL, *expected = NULL;
	size_t ksize, usize;

	umem_src = kmalloc(size, GFP_KERNEL);
	if ((ret |= test(umem_src == NULL, "kmalloc failed")))
		goto out_free;

	expected = kmalloc(size, GFP_KERNEL);
	if ((ret |= test(expected == NULL, "kmalloc failed")))
		goto out_free;

	/* Fill umem with a fixed byte pattern. */
	memset(umem_src, 0x3e, size);
	ret |= test(copy_to_user(umem, umem_src, size),
		    "legitimate copy_to_user failed");

	/* Check basic case -- (usize == ksize). */
	ksize = size;
	usize = size;

	memcpy(expected, umem_src, ksize);

	memset(kmem, 0x0, size);
	ret |= test(copy_struct_from_user(kmem, ksize, umem, usize),
		    "copy_struct_from_user(usize == ksize) failed");
	ret |= test(memcmp(kmem, expected, ksize),
		    "copy_struct_from_user(usize == ksize) gives unexpected copy");

	/* Old userspace case -- (usize < ksize). */
	ksize = size;
	usize = size / 2;

	memcpy(expected, umem_src, usize);
	memset(expected + usize, 0x0, ksize - usize);

	memset(kmem, 0x0, size);
	ret |= test(copy_struct_from_user(kmem, ksize, umem, usize),
		    "copy_struct_from_user(usize < ksize) failed");
	ret |= test(memcmp(kmem, expected, ksize),
		    "copy_struct_from_user(usize < ksize) gives unexpected copy");

	/* New userspace (-E2BIG) case -- (usize > ksize). */
	ksize = size / 2;
	usize = size;

	memset(kmem, 0x0, size);
	ret |= test(copy_struct_from_user(kmem, ksize, umem, usize) != -E2BIG,
		    "copy_struct_from_user(usize > ksize) didn't give E2BIG");

	/* New userspace (success) case -- (usize > ksize). */
	ksize = size / 2;
	usize = size;

	memcpy(expected, umem_src, ksize);
	ret |= test(clear_user(umem + ksize, usize - ksize),
		    "legitimate clear_user failed");

	memset(kmem, 0x0, size);
	ret |= test(copy_struct_from_user(kmem, ksize, umem, usize),
		    "copy_struct_from_user(usize > ksize) failed");
	ret |= test(memcmp(kmem, expected, ksize),
		    "copy_struct_from_user(usize > ksize) gives unexpected copy");

out_free:
	kfree(expected);
	kfree(umem_src);
	return ret;
}

static int __init test_user_copy_init(void)
{
	int ret = 0;
	char *kmem;
	char __user *usermem;
	char *bad_usermem;
	unsigned long user_addr;
	u8 val_u8;
	u16 val_u16;
	u32 val_u32;
#ifdef TEST_U64
	u64 val_u64;
#endif

	kmem = kmalloc(PAGE_SIZE * 2, GFP_KERNEL);
	if (!kmem)
		return -ENOMEM;

	user_addr = vm_mmap(NULL, 0, PAGE_SIZE * 2,
			    PROT_READ | PROT_WRITE | PROT_EXEC,
			    MAP_ANONYMOUS | MAP_PRIVATE, 0);
	if (user_addr >= (unsigned long)(TASK_SIZE)) {
		pr_warn("Failed to allocate user memory\n");
		kfree(kmem);
		return -ENOMEM;
	}

	usermem = (char __user *)user_addr;
	bad_usermem = (char *)user_addr;

	/*
	 * Legitimate usage: none of these copies should fail.
	 */
	memset(kmem, 0x3a, PAGE_SIZE * 2);
	ret |= test(copy_to_user(usermem, kmem, PAGE_SIZE),
		    "legitimate copy_to_user failed");
	memset(kmem, 0x0, PAGE_SIZE);
	ret |= test(copy_from_user(kmem, usermem, PAGE_SIZE),
		    "legitimate copy_from_user failed");
	ret |= test(memcmp(kmem, kmem + PAGE_SIZE, PAGE_SIZE),
		    "legitimate usercopy failed to copy data");

#define test_legit(size, check)						  \
	do {								  \
		val_##size = check;					  \
		ret |= test(put_user(val_##size, (size __user *)usermem), \
		    "legitimate put_user (" #size ") failed");		  \
		val_##size = 0;						  \
		ret |= test(get_user(val_##size, (size __user *)usermem), \
		    "legitimate get_user (" #size ") failed");		  \
		ret |= test(val_##size != check,			  \
		    "legitimate get_user (" #size ") failed to do copy"); \
		if (val_##size != check) {				  \
			pr_info("0x%llx != 0x%llx\n",			  \
				(unsigned long long)val_##size,		  \
				(unsigned long long)check);		  \
		}							  \
	} while (0)

	test_legit(u8,  0x5a);
	test_legit(u16, 0x5a5b);
	test_legit(u32, 0x5a5b5c5d);
#ifdef TEST_U64
	test_legit(u64, 0x5a5b5c5d6a6b6c6d);
#endif
#undef test_legit

	/* Test usage of check_nonzero_user(). */
	ret |= test_check_nonzero_user(kmem, usermem, 2 * PAGE_SIZE);
	/* Test usage of copy_struct_from_user(). */
	ret |= test_copy_struct_from_user(kmem, usermem, 2 * PAGE_SIZE);

	/*
	 * Invalid usage: none of these copies should succeed.
	 */

	/* Prepare kernel memory with check values. */
	memset(kmem, 0x5a, PAGE_SIZE);
	memset(kmem + PAGE_SIZE, 0, PAGE_SIZE);

	/* Reject kernel-to-kernel copies through copy_from_user(). */
	ret |= test(!copy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE),
				    PAGE_SIZE),
		    "illegal all-kernel copy_from_user passed");

	/* Destination half of buffer should have been zeroed. */
	ret |= test(memcmp(kmem + PAGE_SIZE, kmem, PAGE_SIZE),
		    "zeroing failure for illegal all-kernel copy_from_user");

#if 0
	/*
	 * When running with SMAP/PAN/etc, this will Oops the kernel
	 * due to the zeroing of userspace memory on failure. This needs
	 * to be tested in LKDTM instead, since this test module does not
	 * expect to explode.
	 */
	ret |= test(!copy_from_user(bad_usermem, (char __user *)kmem,
				    PAGE_SIZE),
		    "illegal reversed copy_from_user passed");
#endif
	ret |= test(!copy_to_user((char __user *)kmem, kmem + PAGE_SIZE,
				  PAGE_SIZE),
		    "illegal all-kernel copy_to_user passed");
	ret |= test(!copy_to_user((char __user *)kmem, bad_usermem,
				  PAGE_SIZE),
		    "illegal reversed copy_to_user passed");

#define test_illegal(size, check)					    \
	do {								    \
		val_##size = (check);					    \
		ret |= test(!get_user(val_##size, (size __user *)kmem),	    \
		    "illegal get_user (" #size ") passed");		    \
		ret |= test(val_##size != (size)0,			    \
		    "zeroing failure for illegal get_user (" #size ")");    \
		if (val_##size != (size)0) {				    \
			pr_info("0x%llx != 0\n",			    \
				(unsigned long long)val_##size);	    \
		}							    \
		ret |= test(!put_user(val_##size, (size __user *)kmem),	    \
		    "illegal put_user (" #size ") passed");		    \
	} while (0)

	test_illegal(u8,  0x5a);
	test_illegal(u16, 0x5a5b);
	test_illegal(u32, 0x5a5b5c5d);
#ifdef TEST_U64
	test_illegal(u64, 0x5a5b5c5d6a6b6c6d);
#endif
#undef test_illegal

	vm_munmap(user_addr, PAGE_SIZE * 2);
	kfree(kmem);

	if (ret == 0) {
		pr_info("tests passed.\n");
		return 0;
	}

	return -EINVAL;
}

module_init(test_user_copy_init);

static void __exit test_user_copy_exit(void)
{
	pr_info("unloaded.\n");
}

module_exit(test_user_copy_exit);

MODULE_AUTHOR("Kees Cook <keescook@chromium.org>");
MODULE_LICENSE("GPL");
Commit	Line	Data
9c92ab61	1	// SPDX-License-Identifier: GPL-2.0-only
3e2a4c18 KC	2	/*
	3	* Kernel module for testing copy_to/from_user infrastructure.
	4	*
	5	* Copyright 2013 Google Inc. All Rights Reserved
	6	*
	7	* Authors:
	8	* Kees Cook <keescook@chromium.org>
3e2a4c18 KC	9	*/
	10
	11	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	12
	13	#include <linux/mman.h>
	14	#include <linux/module.h>
	15	#include <linux/sched.h>
	16	#include <linux/slab.h>
	17	#include <linux/uaccess.h>
	18	#include <linux/vmalloc.h>
	19
4c5d7bc6 KC	20	/*
	21	* Several 32-bit architectures support 64-bit {get,put}_user() calls.
	22	* As there doesn't appear to be anything that can safely determine
	23	* their capability at compile-time, we just have to opt-out certain archs.
	24	*/
4deaa6fd	25	#if BITS_PER_LONG == 64 \|\| (!(defined(CONFIG_ARM) && !defined(MMU)) && \
4c5d7bc6 KC	26	!defined(CONFIG_M68K) && \
4c5d7bc6 KC	27	!defined(CONFIG_MICROBLAZE) && \
4c5d7bc6 KC	28	!defined(CONFIG_NIOS2) && \
	29	!defined(CONFIG_PPC32) && \
	30	!defined(CONFIG_SUPERH))
	31	# define TEST_U64
	32	#endif
	33
f5a1a536 AS	34	#define test(condition, msg, ...) \
	35	({ \
	36	int cond = (condition); \
	37	if (cond) \
	38	pr_warn("[%d] " msg "\n", __LINE__, ##__VA_ARGS__); \
	39	cond; \
3e2a4c18 KC	40	})
3e2a4c18 KC	41
f5a1a536 AS	42	static bool is_zeroed(void *from, size_t size)
	43	{
	44	return memchr_inv(from, 0x0, size) == NULL;
	45	}
	46
	47	static int test_check_nonzero_user(char kmem, char __user umem, size_t size)
	48	{
	49	int ret = 0;
	50	size_t start, end, i;
	51	size_t zero_start = size / 4;
	52	size_t zero_end = size - zero_start;
	53
	54	/*
	55	* We conduct a series of check_nonzero_user() tests on a block of memory
	56	* with the following byte-pattern (trying every possible [start,end]
	57	* pair):
	58	*
	59	* [ 00 ff 00 ff ... 00 00 00 00 ... ff 00 ff 00 ]
	60	*
	61	* And we verify that check_nonzero_user() acts identically to memchr_inv().
	62	*/
	63
	64	memset(kmem, 0x0, size);
	65	for (i = 1; i < zero_start; i += 2)
	66	kmem[i] = 0xff;
	67	for (i = zero_end; i < size; i += 2)
	68	kmem[i] = 0xff;
	69
	70	ret \|= test(copy_to_user(umem, kmem, size),
	71	"legitimate copy_to_user failed");
	72
	73	for (start = 0; start <= size; start++) {
	74	for (end = start; end <= size; end++) {
	75	size_t len = end - start;
	76	int retval = check_zeroed_user(umem + start, len);
	77	int expected = is_zeroed(kmem + start, len);
	78
	79	ret \|= test(retval != expected,
	80	"check_nonzero_user(=%d) != memchr_inv(=%d) mismatch (start=%zu, end=%zu)",
	81	retval, expected, start, end);
	82	}
	83	}
	84
	85	return ret;
	86	}
	87
	88	static int test_copy_struct_from_user(char kmem, char __user umem,
	89	size_t size)
	90	{
	91	int ret = 0;
	92	char umem_src = NULL, expected = NULL;
	93	size_t ksize, usize;
	94
	95	umem_src = kmalloc(size, GFP_KERNEL);
34111582	96	if ((ret \|= test(umem_src == NULL, "kmalloc failed")))
f5a1a536 AS	97	goto out_free;
	98
	99	expected = kmalloc(size, GFP_KERNEL);
34111582	100	if ((ret \|= test(expected == NULL, "kmalloc failed")))
f5a1a536 AS	101	goto out_free;
	102
	103	/* Fill umem with a fixed byte pattern. */
	104	memset(umem_src, 0x3e, size);
	105	ret \|= test(copy_to_user(umem, umem_src, size),
	106	"legitimate copy_to_user failed");
	107
	108	/* Check basic case -- (usize == ksize). */
	109	ksize = size;
	110	usize = size;
	111
	112	memcpy(expected, umem_src, ksize);
	113
	114	memset(kmem, 0x0, size);
	115	ret \|= test(copy_struct_from_user(kmem, ksize, umem, usize),
	116	"copy_struct_from_user(usize == ksize) failed");
	117	ret \|= test(memcmp(kmem, expected, ksize),
	118	"copy_struct_from_user(usize == ksize) gives unexpected copy");
	119
	120	/* Old userspace case -- (usize < ksize). */
	121	ksize = size;
	122	usize = size / 2;
	123
	124	memcpy(expected, umem_src, usize);
	125	memset(expected + usize, 0x0, ksize - usize);
	126
	127	memset(kmem, 0x0, size);
	128	ret \|= test(copy_struct_from_user(kmem, ksize, umem, usize),
	129	"copy_struct_from_user(usize < ksize) failed");
	130	ret \|= test(memcmp(kmem, expected, ksize),
	131	"copy_struct_from_user(usize < ksize) gives unexpected copy");
	132
	133	/* New userspace (-E2BIG) case -- (usize > ksize). */
	134	ksize = size / 2;
	135	usize = size;
	136
	137	memset(kmem, 0x0, size);
	138	ret \|= test(copy_struct_from_user(kmem, ksize, umem, usize) != -E2BIG,
	139	"copy_struct_from_user(usize > ksize) didn't give E2BIG");
	140
	141	/* New userspace (success) case -- (usize > ksize). */
	142	ksize = size / 2;
	143	usize = size;
	144
	145	memcpy(expected, umem_src, ksize);
	146	ret \|= test(clear_user(umem + ksize, usize - ksize),
	147	"legitimate clear_user failed");
	148
	149	memset(kmem, 0x0, size);
	150	ret \|= test(copy_struct_from_user(kmem, ksize, umem, usize),
	151	"copy_struct_from_user(usize > ksize) failed");
	152	ret \|= test(memcmp(kmem, expected, ksize),
	153	"copy_struct_from_user(usize > ksize) gives unexpected copy");
	154
	155	out_free:
	156	kfree(expected);
	157	kfree(umem_src);
	158	return ret;
	159	}
	160
3e2a4c18 KC	161	static int __init test_user_copy_init(void)
	162	{
	163	int ret = 0;
	164	char *kmem;
	165	char __user *usermem;
	166	char *bad_usermem;
	167	unsigned long user_addr;
4c5d7bc6 KC	168	u8 val_u8;
	169	u16 val_u16;
	170	u32 val_u32;
	171	#ifdef TEST_U64
	172	u64 val_u64;
	173	#endif
3e2a4c18 KC	174
	175	kmem = kmalloc(PAGE_SIZE * 2, GFP_KERNEL);
	176	if (!kmem)
	177	return -ENOMEM;
	178
	179	user_addr = vm_mmap(NULL, 0, PAGE_SIZE * 2,
	180	PROT_READ \| PROT_WRITE \| PROT_EXEC,
	181	MAP_ANONYMOUS \| MAP_PRIVATE, 0);
	182	if (user_addr >= (unsigned long)(TASK_SIZE)) {
	183	pr_warn("Failed to allocate user memory\n");
	184	kfree(kmem);
	185	return -ENOMEM;
	186	}
	187
	188	usermem = (char __user *)user_addr;
	189	bad_usermem = (char *)user_addr;
	190
f5f893c5 KC	191	/*
	192	* Legitimate usage: none of these copies should fail.
	193	*/
4c5d7bc6	194	memset(kmem, 0x3a, PAGE_SIZE * 2);
3e2a4c18 KC	195	ret \|= test(copy_to_user(usermem, kmem, PAGE_SIZE),
3e2a4c18 KC	196	"legitimate copy_to_user failed");
4c5d7bc6 KC	197	memset(kmem, 0x0, PAGE_SIZE);
	198	ret \|= test(copy_from_user(kmem, usermem, PAGE_SIZE),
	199	"legitimate copy_from_user failed");
	200	ret \|= test(memcmp(kmem, kmem + PAGE_SIZE, PAGE_SIZE),
	201	"legitimate usercopy failed to copy data");
	202
	203	#define test_legit(size, check) \
	204	do { \
	205	val_##size = check; \
	206	ret \|= test(put_user(val_##size, (size __user *)usermem), \
	207	"legitimate put_user (" #size ") failed"); \
	208	val_##size = 0; \
	209	ret \|= test(get_user(val_##size, (size __user *)usermem), \
	210	"legitimate get_user (" #size ") failed"); \
	211	ret \|= test(val_##size != check, \
	212	"legitimate get_user (" #size ") failed to do copy"); \
	213	if (val_##size != check) { \
	214	pr_info("0x%llx != 0x%llx\n", \
	215	(unsigned long long)val_##size, \
	216	(unsigned long long)check); \
	217	} \
	218	} while (0)
	219
	220	test_legit(u8, 0x5a);
	221	test_legit(u16, 0x5a5b);
	222	test_legit(u32, 0x5a5b5c5d);
	223	#ifdef TEST_U64
	224	test_legit(u64, 0x5a5b5c5d6a6b6c6d);
	225	#endif
	226	#undef test_legit
3e2a4c18	227
f5a1a536 AS	228	/* Test usage of check_nonzero_user(). */
	229	ret \|= test_check_nonzero_user(kmem, usermem, 2 * PAGE_SIZE);
	230	/* Test usage of copy_struct_from_user(). */
	231	ret \|= test_copy_struct_from_user(kmem, usermem, 2 * PAGE_SIZE);
	232
f5f893c5 KC	233	/*
	234	* Invalid usage: none of these copies should succeed.
	235	*/
	236
	237	/* Prepare kernel memory with check values. */
4fbfeb8b HR	238	memset(kmem, 0x5a, PAGE_SIZE);
4fbfeb8b HR	239	memset(kmem + PAGE_SIZE, 0, PAGE_SIZE);
f5f893c5 KC	240
f5f893c5 KC	241	/* Reject kernel-to-kernel copies through copy_from_user(). */
3e2a4c18 KC	242	ret \|= test(!copy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE),
	243	PAGE_SIZE),
	244	"illegal all-kernel copy_from_user passed");
f5f893c5 KC	245
f5f893c5 KC	246	/* Destination half of buffer should have been zeroed. */
4fbfeb8b HR	247	ret \|= test(memcmp(kmem + PAGE_SIZE, kmem, PAGE_SIZE),
4fbfeb8b HR	248	"zeroing failure for illegal all-kernel copy_from_user");
f5f893c5 KC	249
	250	#if 0
	251	/*
	252	* When running with SMAP/PAN/etc, this will Oops the kernel
	253	* due to the zeroing of userspace memory on failure. This needs
	254	* to be tested in LKDTM instead, since this test module does not
	255	* expect to explode.
	256	*/
3e2a4c18 KC	257	ret \|= test(!copy_from_user(bad_usermem, (char __user *)kmem,
	258	PAGE_SIZE),
	259	"illegal reversed copy_from_user passed");
f5f893c5	260	#endif
3e2a4c18 KC	261	ret \|= test(!copy_to_user((char __user *)kmem, kmem + PAGE_SIZE,
	262	PAGE_SIZE),
	263	"illegal all-kernel copy_to_user passed");
	264	ret \|= test(!copy_to_user((char __user *)kmem, bad_usermem,
	265	PAGE_SIZE),
	266	"illegal reversed copy_to_user passed");
f5f893c5	267
4c5d7bc6 KC	268	#define test_illegal(size, check) \
	269	do { \
	270	val_##size = (check); \
	271	ret \|= test(!get_user(val_##size, (size __user *)kmem), \
	272	"illegal get_user (" #size ") passed"); \
	273	ret \|= test(val_##size != (size)0, \
	274	"zeroing failure for illegal get_user (" #size ")"); \
	275	if (val_##size != (size)0) { \
	276	pr_info("0x%llx != 0\n", \
	277	(unsigned long long)val_##size); \
	278	} \
	279	ret \|= test(!put_user(val_##size, (size __user *)kmem), \
	280	"illegal put_user (" #size ") passed"); \
	281	} while (0)
	282
	283	test_illegal(u8, 0x5a);
	284	test_illegal(u16, 0x5a5b);
	285	test_illegal(u32, 0x5a5b5c5d);
	286	#ifdef TEST_U64
	287	test_illegal(u64, 0x5a5b5c5d6a6b6c6d);
	288	#endif
	289	#undef test_illegal
3e2a4c18 KC	290
	291	vm_munmap(user_addr, PAGE_SIZE * 2);
	292	kfree(kmem);
	293
	294	if (ret == 0) {
	295	pr_info("tests passed.\n");
	296	return 0;
	297	}
	298
	299	return -EINVAL;
	300	}
	301
	302	module_init(test_user_copy_init);
	303
	304	static void __exit test_user_copy_exit(void)
	305	{
	306	pr_info("unloaded.\n");
	307	}
	308
	309	module_exit(test_user_copy_exit);
	310
	311	MODULE_AUTHOR("Kees Cook <keescook@chromium.org>");
	312	MODULE_LICENSE("GPL");