// 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 <kunit/test.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_SPARC32) &&		\			    !defined(CONFIG_SUPERH))# define TEST_U64#endif struct usercopy_test_priv {	char *kmem;	char __user *umem;	size_t size;}; static bool is_zeroed(void *from, size_t size){	return memchr_inv(from, 0x0, size) == NULL;} /* Test usage of check_nonzero_user(). */static void usercopy_test_check_nonzero_user(struct kunit *test){	size_t start, end, i, zero_start, zero_end;	struct usercopy_test_priv *priv = test->priv;	char __user *umem = priv->umem;	char *kmem = priv->kmem;	size_t size = priv->size; 	KUNIT_ASSERT_GE_MSG(test, size, 2 * PAGE_SIZE, "buffer too small"); 	/*	 * We want to cross a page boundary to exercise the code more	 * effectively. We also don't want to make the size we scan too large,	 * otherwise the test can take a long time and cause soft lockups. So	 * scan a 1024 byte region across the page boundary.	 */	size = 1024;	start = PAGE_SIZE - (size / 2); 	kmem += start;	umem += start; 	zero_start = size / 4;	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; 	KUNIT_EXPECT_EQ_MSG(test, copy_to_user(umem, kmem, size), 0,		"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); 			KUNIT_ASSERT_EQ_MSG(test, retval, expected,				"check_nonzero_user(=%d) != memchr_inv(=%d) mismatch (start=%zu, end=%zu)",				retval, expected, start, end);		}	}} /* Test usage of copy_struct_from_user(). */static void usercopy_test_copy_struct_from_user(struct kunit *test){	char *umem_src = NULL, *expected = NULL;	struct usercopy_test_priv *priv = test->priv;	char __user *umem = priv->umem;	char *kmem = priv->kmem;	size_t size = priv->size;	size_t ksize, usize; 	umem_src = kunit_kmalloc(test, size, GFP_KERNEL);	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, umem_src); 	expected = kunit_kmalloc(test, size, GFP_KERNEL);	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, expected); 	/* Fill umem with a fixed byte pattern. */	memset(umem_src, 0x3e, size);	KUNIT_ASSERT_EQ_MSG(test, copy_to_user(umem, umem_src, size), 0,		    "legitimate copy_to_user failed"); 	/* Check basic case -- (usize == ksize). */	ksize = size;	usize = size; 	memcpy(expected, umem_src, ksize); 	memset(kmem, 0x0, size);	KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0,		    "copy_struct_from_user(usize == ksize) failed");	KUNIT_EXPECT_MEMEQ_MSG(test, 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);	KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0,		    "copy_struct_from_user(usize < ksize) failed");	KUNIT_EXPECT_MEMEQ_MSG(test, 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);	KUNIT_EXPECT_EQ_MSG(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);	KUNIT_EXPECT_EQ_MSG(test, clear_user(umem + ksize, usize - ksize), 0,		    "legitimate clear_user failed"); 	memset(kmem, 0x0, size);	KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0,		    "copy_struct_from_user(usize > ksize) failed");	KUNIT_EXPECT_MEMEQ_MSG(test, kmem, expected, ksize,		    "copy_struct_from_user(usize > ksize) gives unexpected copy");} /* * Legitimate usage: none of these copies should fail. */static void usercopy_test_valid(struct kunit *test){	struct usercopy_test_priv *priv = test->priv;	char __user *usermem = priv->umem;	char *kmem = priv->kmem; 	memset(kmem, 0x3a, PAGE_SIZE * 2);	KUNIT_EXPECT_EQ_MSG(test, 0, copy_to_user(usermem, kmem, PAGE_SIZE),	     "legitimate copy_to_user failed");	memset(kmem, 0x0, PAGE_SIZE);	KUNIT_EXPECT_EQ_MSG(test, 0, copy_from_user(kmem, usermem, PAGE_SIZE),	     "legitimate copy_from_user failed");	KUNIT_EXPECT_MEMEQ_MSG(test, kmem, kmem + PAGE_SIZE, PAGE_SIZE,	     "legitimate usercopy failed to copy data"); #define test_legit(size, check)						\	do {								\		size val_##size = (check);				\		KUNIT_EXPECT_EQ_MSG(test, 0,				\			put_user(val_##size, (size __user *)usermem),	\			"legitimate put_user (" #size ") failed");	\		val_##size = 0;						\		KUNIT_EXPECT_EQ_MSG(test, 0,				\			get_user(val_##size, (size __user *)usermem),	\			"legitimate get_user (" #size ") failed");	\		KUNIT_EXPECT_EQ_MSG(test, val_##size, check,		\			"legitimate get_user (" #size ") failed to do copy"); \	} 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} /* * Invalid usage: none of these copies should succeed. */static void usercopy_test_invalid(struct kunit *test){	struct usercopy_test_priv *priv = test->priv;	char __user *usermem = priv->umem;	char *bad_usermem = (char *)usermem;	char *kmem = priv->kmem;	u64 *kmem_u64 = (u64 *)kmem; 	if (IS_ENABLED(CONFIG_ALTERNATE_USER_ADDRESS_SPACE) ||	    !IS_ENABLED(CONFIG_MMU)) {		kunit_skip(test, "Testing for kernel/userspace address confusion is only sensible on architectures with a shared address space");		return;	} 	/* 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(). */	KUNIT_EXPECT_NE_MSG(test, copy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE),						 PAGE_SIZE), 0,		    "illegal all-kernel copy_from_user passed"); 	/* Destination half of buffer should have been zeroed. */	KUNIT_EXPECT_MEMEQ_MSG(test, 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.	 */	KUNIT_EXPECT_NE_MSG(test, copy_from_user(bad_usermem, (char __user *)kmem,						 PAGE_SIZE), 0,		    "illegal reversed copy_from_user passed");#endif	KUNIT_EXPECT_NE_MSG(test, copy_to_user((char __user *)kmem, kmem + PAGE_SIZE,					       PAGE_SIZE), 0,		    "illegal all-kernel copy_to_user passed"); 	KUNIT_EXPECT_NE_MSG(test, copy_to_user((char __user *)kmem, bad_usermem,					       PAGE_SIZE), 0,		    "illegal reversed copy_to_user passed"); #define test_illegal(size, check)							\	do {										\		size val_##size = (check);						\		/* get_user() */							\		KUNIT_EXPECT_NE_MSG(test, get_user(val_##size, (size __user *)kmem), 0,	\		    "illegal get_user (" #size ") passed");				\		KUNIT_EXPECT_EQ_MSG(test, val_##size, 0,				\		    "zeroing failure for illegal get_user (" #size ")");		\		/* put_user() */							\		*kmem_u64 = 0xF09FA4AFF09FA4AF;						\		KUNIT_EXPECT_NE_MSG(test, put_user(val_##size, (size __user *)kmem), 0,	\		    "illegal put_user (" #size ") passed");				\		KUNIT_EXPECT_EQ_MSG(test, *kmem_u64, 0xF09FA4AFF09FA4AF,		\		    "illegal put_user (" #size ") wrote to kernel memory!");		\	} 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} static int usercopy_test_init(struct kunit *test){	struct usercopy_test_priv *priv;	unsigned long user_addr; 	if (!IS_ENABLED(CONFIG_MMU)) {		kunit_skip(test, "Userspace allocation testing not available on non-MMU systems");		return 0;	} 	priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv);	test->priv = priv;	priv->size = PAGE_SIZE * 2; 	priv->kmem = kunit_kmalloc(test, priv->size, GFP_KERNEL);	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv->kmem); 	user_addr = kunit_vm_mmap(test, NULL, 0, priv->size,			    PROT_READ | PROT_WRITE | PROT_EXEC,			    MAP_ANONYMOUS | MAP_PRIVATE, 0);	KUNIT_ASSERT_NE_MSG(test, user_addr, 0,		"Could not create userspace mm");	KUNIT_ASSERT_LT_MSG(test, user_addr, (unsigned long)TASK_SIZE,		"Failed to allocate user memory");	priv->umem = (char __user *)user_addr; 	return 0;} static struct kunit_case usercopy_test_cases[] = {	KUNIT_CASE(usercopy_test_valid),	KUNIT_CASE(usercopy_test_invalid),	KUNIT_CASE(usercopy_test_check_nonzero_user),	KUNIT_CASE(usercopy_test_copy_struct_from_user),	{}}; static struct kunit_suite usercopy_test_suite = {	.name = "usercopy",	.init = usercopy_test_init,	.test_cases = usercopy_test_cases,}; kunit_test_suites(&usercopy_test_suite);MODULE_AUTHOR("Kees Cook <kees@kernel.org>");MODULE_DESCRIPTION("Kernel module for testing copy_to/from_user infrastructure");MODULE_LICENSE("GPL");