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1 | /* |
2 | * Access kernel memory without faulting. |
3 | */ |
4 | #include <linux/uaccess.h> |
5 | #include <linux/module.h> |
6 | #include <linux/mm.h> |
7 | |
8 | /** |
9 | * probe_kernel_read(): safely attempt to read from a location |
10 | * @dst: pointer to the buffer that shall take the data |
11 | * @src: address to read from |
12 | * @size: size of the data chunk |
13 | * |
14 | * Safely read from address @src to the buffer at @dst. If a kernel fault |
15 | * happens, handle that and return -EFAULT. |
16 | */ |
17 | |
18 | long __weak probe_kernel_read(void *dst, void *src, size_t size) |
19 | __attribute__((alias("__probe_kernel_read"))); |
20 | |
21 | long __probe_kernel_read(void *dst, void *src, size_t size) |
22 | { |
23 | long ret; |
24 | mm_segment_t old_fs = get_fs(); |
25 | |
26 | set_fs(KERNEL_DS); |
27 | pagefault_disable(); |
28 | ret = __copy_from_user_inatomic(dst, |
29 | (__force const void __user *)src, size); |
30 | pagefault_enable(); |
31 | set_fs(old_fs); |
32 | |
33 | return ret ? -EFAULT : 0; |
34 | } |
35 | EXPORT_SYMBOL_GPL(probe_kernel_read); |
36 | |
37 | /** |
38 | * probe_kernel_write(): safely attempt to write to a location |
39 | * @dst: address to write to |
40 | * @src: pointer to the data that shall be written |
41 | * @size: size of the data chunk |
42 | * |
43 | * Safely write to address @dst from the buffer at @src. If a kernel fault |
44 | * happens, handle that and return -EFAULT. |
45 | */ |
46 | long __weak probe_kernel_write(void *dst, void *src, size_t size) |
47 | __attribute__((alias("__probe_kernel_write"))); |
48 | |
49 | long __probe_kernel_write(void *dst, void *src, size_t size) |
50 | { |
51 | long ret; |
52 | mm_segment_t old_fs = get_fs(); |
53 | |
54 | set_fs(KERNEL_DS); |
55 | pagefault_disable(); |
56 | ret = __copy_to_user_inatomic((__force void __user *)dst, src, size); |
57 | pagefault_enable(); |
58 | set_fs(old_fs); |
59 | |
60 | return ret ? -EFAULT : 0; |
61 | } |
62 | EXPORT_SYMBOL_GPL(probe_kernel_write); |
63 |
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v2.6.34-rc5
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