1/*
2 * Kernel module for testing copy_to/from_user infrastructure.
3 *
4 * Copyright 2013 Google Inc. All Rights Reserved
5 *
6 * Authors:
7 *      Kees Cook       <keescook@chromium.org>
8 *
9 * This software is licensed under the terms of the GNU General Public
10 * License version 2, as published by the Free Software Foundation, and
11 * may be copied, distributed, and modified under those terms.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16 * GNU General Public License for more details.
17 */
18
19#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21#include <linux/mman.h>
22#include <linux/module.h>
23#include <linux/sched.h>
24#include <linux/slab.h>
25#include <linux/uaccess.h>
26#include <linux/vmalloc.h>
27
28#define test(condition, msg)		\
29({					\
30	int cond = (condition);		\
31	if (cond)			\
32		pr_warn("%s\n", msg);	\
33	cond;				\
34})
35
36static int __init test_user_copy_init(void)
37{
38	int ret = 0;
39	char *kmem;
40	char __user *usermem;
41	char *bad_usermem;
42	unsigned long user_addr;
43	unsigned long value = 0x5A;
44
45	kmem = kmalloc(PAGE_SIZE * 2, GFP_KERNEL);
46	if (!kmem)
47		return -ENOMEM;
48
49	user_addr = vm_mmap(NULL, 0, PAGE_SIZE * 2,
50			    PROT_READ | PROT_WRITE | PROT_EXEC,
51			    MAP_ANONYMOUS | MAP_PRIVATE, 0);
52	if (user_addr >= (unsigned long)(TASK_SIZE)) {
53		pr_warn("Failed to allocate user memory\n");
54		kfree(kmem);
55		return -ENOMEM;
56	}
57
58	usermem = (char __user *)user_addr;
59	bad_usermem = (char *)user_addr;
60
61	/* Legitimate usage: none of these should fail. */
62	ret |= test(copy_from_user(kmem, usermem, PAGE_SIZE),
63		    "legitimate copy_from_user failed");
64	ret |= test(copy_to_user(usermem, kmem, PAGE_SIZE),
65		    "legitimate copy_to_user failed");
66	ret |= test(get_user(value, (unsigned long __user *)usermem),
67		    "legitimate get_user failed");
68	ret |= test(put_user(value, (unsigned long __user *)usermem),
69		    "legitimate put_user failed");
70
71	/* Invalid usage: none of these should succeed. */
72	ret |= test(!copy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE),
73				    PAGE_SIZE),
74		    "illegal all-kernel copy_from_user passed");
75	ret |= test(!copy_from_user(bad_usermem, (char __user *)kmem,
76				    PAGE_SIZE),
77		    "illegal reversed copy_from_user passed");
78	ret |= test(!copy_to_user((char __user *)kmem, kmem + PAGE_SIZE,
79				  PAGE_SIZE),
80		    "illegal all-kernel copy_to_user passed");
81	ret |= test(!copy_to_user((char __user *)kmem, bad_usermem,
82				  PAGE_SIZE),
83		    "illegal reversed copy_to_user passed");
84	ret |= test(!get_user(value, (unsigned long __user *)kmem),
85		    "illegal get_user passed");
86	ret |= test(!put_user(value, (unsigned long __user *)kmem),
87		    "illegal put_user passed");
88
89	vm_munmap(user_addr, PAGE_SIZE * 2);
90	kfree(kmem);
91
92	if (ret == 0) {
93		pr_info("tests passed.\n");
94		return 0;
95	}
96
97	return -EINVAL;
98}
99
100module_init(test_user_copy_init);
101
102static void __exit test_user_copy_exit(void)
103{
104	pr_info("unloaded.\n");
105}
106
107module_exit(test_user_copy_exit);
108
109MODULE_AUTHOR("Kees Cook <keescook@chromium.org>");
110MODULE_LICENSE("GPL");
111