maccess: remove strncpy_from_unsafe

extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);

extern long notrace probe_user_write(void __user *dst, const void *src, size_t size);

extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);

long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr,

		long count);

static long __probe_kernel_read(void *dst, const void *src, size_t size,

		bool strict);

static long __strncpy_from_unsafe(char *dst, const void *unsafe_addr,

		long count, bool strict);

bool __weak probe_kernel_read_allowed(const void *unsafe_src, size_t size,

		bool strict)

}

EXPORT_SYMBOL_GPL(probe_user_write);

/**

 * strncpy_from_unsafe: - Copy a NUL terminated string from unsafe address.

 * @dst:   Destination address, in kernel space.  This buffer must be at

 *         least @count bytes long.

 * @unsafe_addr: Unsafe address.

 * @count: Maximum number of bytes to copy, including the trailing NUL.

 *

 * Copies a NUL-terminated string from unsafe address to kernel buffer.

 *

 * On success, returns the length of the string INCLUDING the trailing NUL.

 *

 * If access fails, returns -EFAULT (some data may have been copied

 * and the trailing NUL added).

 *

 * If @count is smaller than the length of the string, copies @count-1 bytes,

 * sets the last byte of @dst buffer to NUL and returns @count.

 *

 * Same as strncpy_from_kernel_nofault() except that for architectures with

 * not fully separated user and kernel address spaces this function also works

 * for user address tanges.

 *

 * DO NOT USE THIS FUNCTION - it is broken on architectures with entirely

 * separate kernel and user address spaces, and also a bad idea otherwise.

 */

long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)

{

	return __strncpy_from_unsafe(dst, unsafe_addr, count, false);

}

/**

 * strncpy_from_kernel_nofault: - Copy a NUL terminated string from unsafe

 *				 address.

 * sets the last byte of @dst buffer to NUL and returns @count.

 */

long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)

{

	return __strncpy_from_unsafe(dst, unsafe_addr, count, true);

}

static long __strncpy_from_unsafe(char *dst, const void *unsafe_addr,

		long count, bool strict)

{

	mm_segment_t old_fs = get_fs();

	const void *src = unsafe_addr;

	if (unlikely(count <= 0))

		return 0;

	if (!probe_kernel_read_allowed(unsafe_addr, count, strict))

	if (!probe_kernel_read_allowed(unsafe_addr, count, true))

		return -EFAULT;

	set_fs(KERNEL_DS);