Commit dbb7ee0e authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by David S. Miller
Browse files

lib: move strncpy_from_unsafe() into mm/maccess.c 



To fix build errors:
kernel/built-in.o: In function `bpf_trace_printk':
bpf_trace.c:(.text+0x11a254): undefined reference to `strncpy_from_unsafe'
kernel/built-in.o: In function `fetch_memory_string':
trace_kprobe.c:(.text+0x11acf8): undefined reference to `strncpy_from_unsafe'

move strncpy_from_unsafe() next to probe_kernel_read/write()
which use the same memory access style.

Reported-by: default avatarFengguang Wu <fengguang.wu@intel.com>
Reported-by: default avatarGuenter Roeck <linux@roeck-us.net>
Fixes: 1a6877b9 ("lib: introduce strncpy_from_unsafe()")
Signed-off-by: default avatarAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9dc30648

lib/strncpy_from_user.c

+0 −41
Original line number Diff line number Diff line
@@ -112,44 +112,3 @@ long strncpy_from_user(char *dst, const char __user *src, long count) 
	return -EFAULT;

}

EXPORT_SYMBOL(strncpy_from_user);
 


/**

 * 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.

 * @src:   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.

 */

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

{

	mm_segment_t old_fs = get_fs();

	const void *src = unsafe_addr;

	long ret;



	if (unlikely(count <= 0))

		return 0;



	set_fs(KERNEL_DS);

	pagefault_disable();



	do {

		ret = __copy_from_user_inatomic(dst++,

						(const void __user __force *)src++, 1);

	} while (dst[-1] && ret == 0 && src - unsafe_addr < count);



	dst[-1] = '\0';

	pagefault_enable();

	set_fs(old_fs);



	return ret < 0 ? ret : src - unsafe_addr;

}

mm/maccess.c

+41 −0
Original line number Diff line number Diff line
@@ -60,3 +60,44 @@ long __probe_kernel_write(void *dst, const void *src, size_t size) 
	return ret ? -EFAULT : 0;

}

EXPORT_SYMBOL_GPL(probe_kernel_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.

 * @src:   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.

 */

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

{

	mm_segment_t old_fs = get_fs();

	const void *src = unsafe_addr;

	long ret;



	if (unlikely(count <= 0))

		return 0;



	set_fs(KERNEL_DS);

	pagefault_disable();



	do {

		ret = __copy_from_user_inatomic(dst++,

						(const void __user __force *)src++, 1);

	} while (dst[-1] && ret == 0 && src - unsafe_addr < count);



	dst[-1] = '\0';

	pagefault_enable();

	set_fs(old_fs);



	return ret < 0 ? ret : src - unsafe_addr;

}

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