63 lines
1.6 KiB
C
63 lines
1.6 KiB
C
/*
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* Access kernel memory without faulting.
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*/
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#include <linux/uaccess.h>
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#include <linux/module.h>
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#include <linux/mm.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, void *src, size_t size)
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__attribute__((alias("__probe_kernel_read")));
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long __probe_kernel_read(void *dst, 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, void *src, size_t size)
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__attribute__((alias("__probe_kernel_write")));
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long __probe_kernel_write(void *dst, 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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