// 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 <[email protected]>
*/
#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 <[email protected]>");
MODULE_DESCRIPTION("Kernel module for testing copy_to/from_user infrastructure");
MODULE_LICENSE("GPL");
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