From patchwork Tue Jul 23 00:38:15 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joe Perches X-Patchwork-Id: 11053697 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4F82C112C for ; Tue, 23 Jul 2019 00:38:42 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3D9EC2845C for ; Tue, 23 Jul 2019 00:38:42 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 319BE2847E; Tue, 23 Jul 2019 00:38:42 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 9435E2845C for ; Tue, 23 Jul 2019 00:38:40 +0000 (UTC) Received: (qmail 23670 invoked by uid 550); 23 Jul 2019 00:38:36 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 22513 invoked from network); 23 Jul 2019 00:38:35 -0000 X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: wheel67_2bd70514adf25 X-Filterd-Recvd-Size: 3459 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: X-Virus-Scanned: ClamAV using ClamSMTP 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 Reviewed-by: Kees Cook --- 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 From patchwork Tue Jul 23 00:38:16 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joe Perches X-Patchwork-Id: 11053699 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B59E6112C for ; Tue, 23 Jul 2019 00:38:47 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A25522845C for ; Tue, 23 Jul 2019 00:38:47 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 955CA284FF; Tue, 23 Jul 2019 00:38:47 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id B9C042845C for ; Tue, 23 Jul 2019 00:38:46 +0000 (UTC) Received: (qmail 24003 invoked by uid 550); 23 Jul 2019 00:38:38 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 23885 invoked from network); 23 Jul 2019 00:38:38 -0000 X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: brake82_2c3d0225c592a X-Filterd-Recvd-Size: 3890 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 , linux-doc@vger.kernel.org Subject: [PATCH 2/2] kernel-doc: core-api: Include string.h into core-api Date: Mon, 22 Jul 2019 17:38:16 -0700 Message-Id: <224a6ebf39955f4107c0c376d66155d970e46733.1563841972.git.joe@perches.com> X-Mailer: git-send-email 2.15.0 In-Reply-To: References: X-Virus-Scanned: ClamAV using ClamSMTP core-api should show all the various string functions including the newly added stracpy and stracpy_pad. Miscellanea: o Update the Returns: value for strscpy o fix a defect with %NUL) Signed-off-by: Joe Perches Reviewed-by: Kees Cook --- Documentation/core-api/kernel-api.rst | 3 +++ include/linux/string.h | 5 +++-- lib/string.c | 10 ++++++---- 3 files changed, 12 insertions(+), 6 deletions(-) diff --git a/Documentation/core-api/kernel-api.rst b/Documentation/core-api/kernel-api.rst index 08af5caf036d..f77de49b1d51 100644 --- a/Documentation/core-api/kernel-api.rst +++ b/Documentation/core-api/kernel-api.rst @@ -42,6 +42,9 @@ String Manipulation .. kernel-doc:: lib/string.c :export: +.. kernel-doc:: include/linux/string.h + :internal: + .. kernel-doc:: mm/util.c :functions: kstrdup kstrdup_const kstrndup kmemdup kmemdup_nul memdup_user vmemdup_user strndup_user memdup_user_nul diff --git a/include/linux/string.h b/include/linux/string.h index f80b0973f0e5..329188fffc11 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -515,8 +515,9 @@ static inline void memcpy_and_pad(void *dest, size_t dest_len, * But this can lead to bugs due to typos, or if prefix is a pointer * and not a constant. Instead use str_has_prefix(). * - * Returns: 0 if @str does not start with @prefix - strlen(@prefix) if @str does start with @prefix + * Returns: + * * strlen(@prefix) if @str starts with @prefix + * * 0 if @str does not start with @prefix */ static __always_inline size_t str_has_prefix(const char *str, const char *prefix) { diff --git a/lib/string.c b/lib/string.c index 461fb620f85f..53582b6dce2a 100644 --- a/lib/string.c +++ b/lib/string.c @@ -173,8 +173,9 @@ EXPORT_SYMBOL(strlcpy); * doesn't unnecessarily force the tail of the destination buffer to be * zeroed. If zeroing is desired please use strscpy_pad(). * - * Return: The number of characters copied (not including the trailing - * %NUL) or -E2BIG if the destination buffer wasn't big enough. + * Returns: + * * The number of characters copied (not including the trailing %NUL) + * * -E2BIG if count is 0. */ ssize_t strscpy(char *dest, const char *src, size_t count) { @@ -253,8 +254,9 @@ EXPORT_SYMBOL(strscpy); * For full explanation of why you may want to consider using the * 'strscpy' functions please see the function docstring for strscpy(). * - * Return: The number of characters copied (not including the trailing - * %NUL) or -E2BIG if the destination buffer wasn't big enough. + * Returns: + * * The number of characters copied (not including the trailing %NUL) + * * -E2BIG if count is 0. */ ssize_t strscpy_pad(char *dest, const char *src, size_t count) {