Commit 8366d124 authored by Kees Cook's avatar Kees Cook
Browse files

string: Allow 2-argument strscpy_pad() 



Similar to strscpy(), update strscpy_pad()'s 3rd argument to be
optional when the destination is a compile-time known size array.

Cc: Andy Shevchenko <andy@kernel.org>
Cc:  <linux-hardening@vger.kernel.org>
Reviewed-by: default avatarJustin Stitt <justinstitt@google.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
parent e6584c39

include/linux/string.h

+20 −13
Original line number Diff line number Diff line
@@ -77,6 +77,10 @@ ssize_t sized_strscpy(char *, const char *, size_t); 
	sized_strscpy(dst, src, sizeof(dst) + __must_be_array(dst))

#define __strscpy1(dst, src, size)	sized_strscpy(dst, src, size)



#define __strscpy_pad0(dst, src, ...)	\

	sized_strscpy_pad(dst, src, sizeof(dst) + __must_be_array(dst))

#define __strscpy_pad1(dst, src, size)	sized_strscpy_pad(dst, src, size)



/**

 * strscpy - Copy a C-string into a sized buffer

 * @dst: Where to copy the string to
@@ -102,11 +106,23 @@ ssize_t sized_strscpy(char *, const char *, size_t); 
#define strscpy(dst, src, ...)	\

	CONCATENATE(__strscpy, COUNT_ARGS(__VA_ARGS__))(dst, src, __VA_ARGS__)



#define sized_strscpy_pad(dest, src, count)	({			\

	char *__dst = (dest);						\

	const char *__src = (src);					\

	const size_t __count = (count);					\

	ssize_t __wrote;						\

									\

	__wrote = sized_strscpy(__dst, __src, __count);			\

	if (__wrote >= 0 && __wrote < __count)				\

		memset(__dst + __wrote + 1, 0, __count - __wrote - 1);	\

	__wrote;							\

})



/**

 * strscpy_pad() - Copy a C-string into a sized buffer

 * @dest: Where to copy the string to

 * @dst: Where to copy the string to

 * @src: Where to copy the string from

 * @count: Size of destination buffer

 * @...: Size of destination buffer

 *

 * Copy the string, or as much of it as fits, into the dest buffer. The

 * behavior is undefined if the string buffers overlap. The destination
@@ -122,17 +138,8 @@ ssize_t sized_strscpy(char *, const char *, size_t); 
 * * The number of characters copied (not including the trailing %NULs)

 * * -E2BIG if count is 0 or @src was truncated.

 */

#define strscpy_pad(dest, src, count)	({			\

	char *__dst = (dest);						\

	const char *__src = (src);					\

	const size_t __count = (count);					\

	ssize_t __wrote;						\

									\

	__wrote = strscpy(__dst, __src, __count);			\

	if (__wrote >= 0 && __wrote < __count)				\

		memset(__dst + __wrote + 1, 0, __count - __wrote - 1);	\

	__wrote;							\

})

#define strscpy_pad(dst, src, ...)	\

	CONCATENATE(__strscpy_pad, COUNT_ARGS(__VA_ARGS__))(dst, src, __VA_ARGS__)



#ifndef __HAVE_ARCH_STRCAT

extern char * strcat(char *, const char *);