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// 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("%s\n", msg); \
cond; \
})
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
/*
* 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");
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