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| 1 | /* |
| 2 | * Access kernel memory without faulting. |
| 3 | */ |
| 4 | #include <linux/export.h> |
| 5 | #include <linux/mm.h> |
| 6 | #include <linux/uaccess.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, const void *src, size_t size) |
| 19 | __attribute__((alias("__probe_kernel_read"))); |
| 20 | |
| 21 | long __probe_kernel_read(void *dst, const 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, const void *src, size_t size) |
| 47 | __attribute__((alias("__probe_kernel_write"))); |
| 48 | |
| 49 | long __probe_kernel_write(void *dst, const 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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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
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v3.9
