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 5A8FAC7618B for ; Tue, 23 Jul 2019 13:51:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 307FA227B9 for ; Tue, 23 Jul 2019 13:51:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390425AbfGWNvs (ORCPT ); Tue, 23 Jul 2019 09:51:48 -0400 Received: from smtprelay0024.hostedemail.com ([216.40.44.24]:45255 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726527AbfGWNvp (ORCPT ); Tue, 23 Jul 2019 09:51:45 -0400 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay04.hostedemail.com (Postfix) with ESMTP id 320E7180A814E; Tue, 23 Jul 2019 13:51:44 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: silk37_83499df992928 X-Filterd-Recvd-Size: 3970 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 omf12.hostedemail.com (Postfix) with ESMTPA; Tue, 23 Jul 2019 13:51:42 +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 V2 1/2] string: Add stracpy and stracpy_pad mechanisms Date: Tue, 23 Jul 2019 06:51:36 -0700 Message-Id: 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 (dest) and uses sizeof(dest) as the count of bytes to copy. These mechanisms verify that the dest argument is an array of char or other compatible types like u8 or s8 or equivalent. A BUILD_BUG is emitted when the type of dest is not compatible. Signed-off-by: Joe Perches --- V2: Use __same_type testing char[], signed char[], and unsigned char[] Rename to, from, and size, dest, src and count Correct return of -E2BIG descriptions include/linux/string.h | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/include/linux/string.h b/include/linux/string.h index 4deb11f7976b..7572cd78cf9f 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -35,6 +35,51 @@ 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/u8/s8 or equivalent + * @dest: Where to copy the string, must be an array of char and not a pointer + * @src: String to copy, may be a pointer or const char array + * + * Helper for strscpy(). + * Copies a maximum of sizeof(@dest) bytes of @src with %NUL termination. + * + * Returns: + * * The number of characters copied (not including the trailing %NUL) + * * -E2BIG if @dest is a zero size array or @src was truncated. + */ +#define stracpy(dest, src) \ +({ \ + size_t count = ARRAY_SIZE(dest); \ + BUILD_BUG_ON(!(__same_type(dest, char[]) || \ + __same_type(dest, unsigned char[]) || \ + __same_type(dest, signed char[]))); \ + \ + strscpy(dest, src, count); \ +}) + +/** + * stracpy_pad - Copy a C-string into an array of char/u8/s8 with %NUL padding + * @dest: Where to copy the string, must be an array of char and not a pointer + * @src: String to copy, may be a pointer or const char array + * + * Helper for strscpy_pad(). + * Copies a maximum of sizeof(@dest) bytes of @src with %NUL termination + * and zero-pads the remaining size of @dest + * + * Returns: + * * The number of characters copied (not including the trailing %NUL) + * * -E2BIG if @dest is a zero size array or @src was truncated. + */ +#define stracpy_pad(dest, src) \ +({ \ + size_t count = ARRAY_SIZE(dest); \ + BUILD_BUG_ON(!(__same_type(dest, char[]) || \ + __same_type(dest, unsigned char[]) || \ + __same_type(dest, signed char[]))); \ + \ + strscpy_pad(dest, src, count); \ +}) + #ifndef __HAVE_ARCH_STRCAT extern char * strcat(char *, const char *); #endif -- 2.15.0