-// 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_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");