1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
|
/*
* Kernel module for testing copy_to/from_user infrastructure.
*
* Copyright 2013 Google Inc. All Rights Reserved
*
* Authors:
* Kees Cook <keescook@chromium.org>
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#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_AVR32) && \
!defined(CONFIG_BLACKFIN) && \
!defined(CONFIG_M32R) && \
!defined(CONFIG_M68K) && \
!defined(CONFIG_MICROBLAZE) && \
!defined(CONFIG_MN10300) && \
!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");
|
