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62 lines
1.6 KiB
62 lines
1.6 KiB
/* |
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* Access kernel memory without faulting. |
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*/ |
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#include <linux/export.h> |
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#include <linux/mm.h> |
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#include <linux/uaccess.h> |
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/** |
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* probe_kernel_read(): safely attempt to read from a location |
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* @dst: pointer to the buffer that shall take the data |
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* @src: address to read from |
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* @size: size of the data chunk |
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* |
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* Safely read from address @src to the buffer at @dst. If a kernel fault |
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* happens, handle that and return -EFAULT. |
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*/ |
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long __weak probe_kernel_read(void *dst, const void *src, size_t size) |
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__attribute__((alias("__probe_kernel_read"))); |
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long __probe_kernel_read(void *dst, const void *src, size_t size) |
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{ |
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long ret; |
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mm_segment_t old_fs = get_fs(); |
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set_fs(KERNEL_DS); |
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pagefault_disable(); |
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ret = __copy_from_user_inatomic(dst, |
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(__force const void __user *)src, size); |
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pagefault_enable(); |
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set_fs(old_fs); |
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return ret ? -EFAULT : 0; |
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} |
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EXPORT_SYMBOL_GPL(probe_kernel_read); |
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/** |
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* probe_kernel_write(): safely attempt to write to a location |
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* @dst: address to write to |
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* @src: pointer to the data that shall be written |
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* @size: size of the data chunk |
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* |
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* Safely write to address @dst from the buffer at @src. If a kernel fault |
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* happens, handle that and return -EFAULT. |
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*/ |
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long __weak probe_kernel_write(void *dst, const void *src, size_t size) |
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__attribute__((alias("__probe_kernel_write"))); |
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long __probe_kernel_write(void *dst, const void *src, size_t size) |
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{ |
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long ret; |
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mm_segment_t old_fs = get_fs(); |
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set_fs(KERNEL_DS); |
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pagefault_disable(); |
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ret = __copy_to_user_inatomic((__force void __user *)dst, src, size); |
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pagefault_enable(); |
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set_fs(old_fs); |
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return ret ? -EFAULT : 0; |
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} |
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EXPORT_SYMBOL_GPL(probe_kernel_write);
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