Commit d2627006 authored by Kees Cook's avatar Kees Cook
Browse files

string: Remove strlcpy() 

With all the users of strlcpy() removed[1] from the kernel, remove the
API, self-tests, and other references. Leave mentions in Documentation
(about its deprecation), and in checkpatch.pl (to help migrate host-only
tools/ usage). Long live strscpy().

Link: https://github.com/KSPP/linux/issues/89

 [1]
Cc: Azeem Shaikh <azeemshaikh38@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Joe Perches <joe@perches.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: linux-hardening@vger.kernel.org
Reviewed-by: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
parent e28b0359

include/linux/fortify-string.h

+0 −51
Original line number Diff line number Diff line
@@ -214,51 +214,6 @@ __kernel_size_t __fortify_strlen(const char * const POS p) 
	return ret;

}



/* Defined after fortified strlen() to reuse it. */

extern size_t __real_strlcpy(char *, const char *, size_t) __RENAME(strlcpy);

/**

 * strlcpy - Copy a string into another string buffer

 *

 * @p: pointer to destination of copy

 * @q: pointer to NUL-terminated source string to copy

 * @size: maximum number of bytes to write at @p

 *

 * If strlen(@q) >= @size, the copy of @q will be truncated at

 * @size - 1 bytes. @p will always be NUL-terminated.

 *

 * Do not use this function. While FORTIFY_SOURCE tries to avoid

 * over-reads when calculating strlen(@q), it is still possible.

 * Prefer strscpy(), though note its different return values for

 * detecting truncation.

 *

 * Returns total number of bytes written to @p, including terminating NUL.

 *

 */

__FORTIFY_INLINE size_t strlcpy(char * const POS p, const char * const POS q, size_t size)

{

	const size_t p_size = __member_size(p);

	const size_t q_size = __member_size(q);

	size_t q_len;	/* Full count of source string length. */

	size_t len;	/* Count of characters going into destination. */



	if (p_size == SIZE_MAX && q_size == SIZE_MAX)

		return __real_strlcpy(p, q, size);

	q_len = strlen(q);

	len = (q_len >= size) ? size - 1 : q_len;

	if (__builtin_constant_p(size) && __builtin_constant_p(q_len) && size) {

		/* Write size is always larger than destination. */

		if (len >= p_size)

			__write_overflow();

	}

	if (size) {

		if (len >= p_size)

			fortify_panic(__func__);

		__underlying_memcpy(p, q, len);

		p[len] = '\0';

	}

	return q_len;

}



/* Defined after fortified strnlen() to reuse it. */

extern ssize_t __real_strscpy(char *, const char *, size_t) __RENAME(strscpy);

/**
@@ -272,12 +227,6 @@ extern ssize_t __real_strscpy(char *, const char *, size_t) __RENAME(strscpy); 
 * @p buffer. The behavior is undefined if the string buffers overlap. The

 * destination @p buffer is always NUL terminated, unless it's zero-sized.

 *

 * Preferred to strlcpy() since the API doesn't require reading memory

 * from the source @q string beyond the specified @size bytes, and since

 * the return value is easier to error-check than strlcpy()'s.

 * In addition, the implementation is robust to the string changing out

 * from underneath it, unlike the current strlcpy() implementation.

 *

 * Preferred to strncpy() since it always returns a valid string, and

 * doesn't unnecessarily force the tail of the destination buffer to be

 * zero padded. If padding is desired please use strscpy_pad().

include/linux/string.h

+0 −3
Original line number Diff line number Diff line
@@ -66,9 +66,6 @@ extern char * strcpy(char *,const char *); 
#ifndef __HAVE_ARCH_STRNCPY

extern char * strncpy(char *,const char *, __kernel_size_t);

#endif

#ifndef __HAVE_ARCH_STRLCPY

size_t strlcpy(char *, const char *, size_t);

#endif

#ifndef __HAVE_ARCH_STRSCPY

ssize_t strscpy(char *, const char *, size_t);

#endif

lib/nlattr.c

+1 −1
Original line number Diff line number Diff line
@@ -758,7 +758,7 @@ EXPORT_SYMBOL(nla_find); 
 * @dstsize: Size of destination buffer.

 *

 * Copies at most dstsize - 1 bytes into the destination buffer.

 * Unlike strlcpy the destination buffer is always padded out.

 * Unlike strscpy() the destination buffer is always padded out.

 *

 * Return:

 * * srclen - Returns @nla length (not including the trailing %NUL).

lib/string.c

+0 −15
Original line number Diff line number Diff line
@@ -103,21 +103,6 @@ char *strncpy(char *dest, const char *src, size_t count) 
EXPORT_SYMBOL(strncpy);

#endif



#ifndef __HAVE_ARCH_STRLCPY

size_t strlcpy(char *dest, const char *src, size_t size)

{

	size_t ret = strlen(src);



	if (size) {

		size_t len = (ret >= size) ? size - 1 : ret;

		__builtin_memcpy(dest, src, len);

		dest[len] = '\0';

	}

	return ret;

}

EXPORT_SYMBOL(strlcpy);

#endif



#ifndef __HAVE_ARCH_STRSCPY

ssize_t strscpy(char *dest, const char *src, size_t count)

{

lib/test_fortify/write_overflow-strlcpy-src.c

deleted100644 → 0
+0 −5
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

#define TEST	\

	strlcpy(small, large_src, sizeof(small) + 1)



#include "test_fortify.h"