From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AC613C76190 for ; Tue, 23 Jul 2019 00:38:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8EA6C218BE for ; Tue, 23 Jul 2019 00:38:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733149AbfGWAi0 (ORCPT ); Mon, 22 Jul 2019 20:38:26 -0400 Received: from smtprelay0192.hostedemail.com ([216.40.44.192]:50395 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728573AbfGWAiY (ORCPT ); Mon, 22 Jul 2019 20:38:24 -0400 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay03.hostedemail.com (Postfix) with ESMTP id 33C9A83777ED; Tue, 23 Jul 2019 00:38:23 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: wheel67_2bd70514adf25 X-Filterd-Recvd-Size: 3459 Received: from joe-laptop.perches.com (cpe-23-242-196-136.socal.res.rr.com [23.242.196.136]) (Authenticated sender: joe@perches.com) by omf13.hostedemail.com (Postfix) with ESMTPA; Tue, 23 Jul 2019 00:38:21 +0000 (UTC) From: Joe Perches To: Linus Torvalds , linux-kernel@vger.kernel.org Cc: Jonathan Corbet , Stephen Kitt , Kees Cook , Nitin Gote , jannh@google.com, kernel-hardening@lists.openwall.com, Rasmus Villemoes , Andrew Morton Subject: [PATCH 1/2] string: Add stracpy and stracpy_pad mechanisms Date: Mon, 22 Jul 2019 17:38:15 -0700 Message-Id: <7ab8957eaf9b0931a59eff6e2bd8c5169f2f6c41.1563841972.git.joe@perches.com> X-Mailer: git-send-email 2.15.0 In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Several uses of strlcpy and strscpy have had defects because the last argument of each function is misused or typoed. Add macro mechanisms to avoid this defect. stracpy (copy a string to a string array) must have a string array as the first argument (to) and uses sizeof(to) as the size. These mechanisms verify that the to argument is an array of char or other compatible types like u8 or unsigned char. A BUILD_BUG is emitted when the type of to is not compatible. Signed-off-by: Joe Perches --- include/linux/string.h | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/include/linux/string.h b/include/linux/string.h index 4deb11f7976b..f80b0973f0e5 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -35,6 +35,47 @@ ssize_t strscpy(char *, const char *, size_t); /* Wraps calls to strscpy()/memset(), no arch specific code required */ ssize_t strscpy_pad(char *dest, const char *src, size_t count); +/** + * stracpy - Copy a C-string into an array of char + * @to: Where to copy the string, must be an array of char and not a pointer + * @from: String to copy, may be a pointer or const char array + * + * Helper for strscpy. + * Copies a maximum of sizeof(@to) bytes of @from with %NUL termination. + * + * Returns: + * * The number of characters copied (not including the trailing %NUL) + * * -E2BIG if @to is a zero size array. + */ +#define stracpy(to, from) \ +({ \ + size_t size = ARRAY_SIZE(to); \ + BUILD_BUG_ON(!__same_type(typeof(*to), char)); \ + \ + strscpy(to, from, size); \ +}) + +/** + * stracpy_pad - Copy a C-string into an array of char with %NUL padding + * @to: Where to copy the string, must be an array of char and not a pointer + * @from: String to copy, may be a pointer or const char array + * + * Helper for strscpy_pad. + * Copies a maximum of sizeof(@to) bytes of @from with %NUL termination + * and zero-pads the remaining size of @to + * + * Returns: + * * The number of characters copied (not including the trailing %NUL) + * * -E2BIG if @to is a zero size array. + */ +#define stracpy_pad(to, from) \ +({ \ + size_t size = ARRAY_SIZE(to); \ + BUILD_BUG_ON(!__same_type(typeof(*to), char)); \ + \ + strscpy_pad(to, from, size); \ +}) + #ifndef __HAVE_ARCH_STRCAT extern char * strcat(char *, const char *); #endif -- 2.15.0