string: Redefine strscpy_pad() as a macro

In preparation for making strscpy_pad()'s 3rd argument optional, redefine
it as a macro. This also has the benefit of allowing greater FORITFY
introspection, as it couldn't see into the strscpy() nor the memset()
within strscpy_pad().

Cc: Andy Shevchenko <andy@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc:  <linux-hardening@vger.kernel.org>
Reviewed-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>

1 files changed, 0 insertions, 34 deletions

diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index 7713f73e66b0f3..606c3099013fdd 100644
--- a/lib/string_helpers.c
+++ b/lib/string_helpers.c
@@ -826,40 +826,6 @@ char **devm_kasprintf_strarray(struct device *dev, const char *prefix, size_t n)
 EXPORT_SYMBOL_GPL(devm_kasprintf_strarray);
 
 /**
- * strscpy_pad() - Copy a C-string into a sized buffer
- * @dest: Where to copy the string to
- * @src: Where to copy the string from
- * @count: 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
- * buffer is always %NUL terminated, unless it's zero-sized.
- *
- * If the source string is shorter than the destination buffer, zeros
- * the tail of the destination buffer.
- *
- * For full explanation of why you may want to consider using the
- * 'strscpy' functions please see the function docstring for strscpy().
- *
- * Returns:
- * * The number of characters copied (not including the trailing %NUL)
- * * -E2BIG if count is 0 or @src was truncated.
- */
-ssize_t strscpy_pad(char *dest, const char *src, size_t count)
-{
-	ssize_t written;
-
-	written = strscpy(dest, src, count);
-	if (written < 0 || written == count - 1)
-		return written;
-
-	memset(dest + written + 1, 0, count - written - 1);
-
-	return written;
-}
-EXPORT_SYMBOL(strscpy_pad);
-
-/**
  * skip_spaces - Removes leading whitespace from @str.
  * @str: The string to be stripped.
  *