From patchwork Wed Aug 16 14:06:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Przemek Kitszel X-Patchwork-Id: 13355235 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE013C001E0 for ; Wed, 16 Aug 2023 14:10:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245551AbjHPOJz (ORCPT ); Wed, 16 Aug 2023 10:09:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44604 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343517AbjHPOJ1 (ORCPT ); Wed, 16 Aug 2023 10:09:27 -0400 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E5E65210D; Wed, 16 Aug 2023 07:09:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1692194966; x=1723730966; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=YAn+qFaH+cnaD9dMJiaWeGa/bW1pztO7/1R5Eu3mjwI=; b=FGTsxv+0pF1E0WAhLjKLvtUGFbmI0xpoZ52/QdcS49NnENs6sIi01sZT H5aCRKsMREK4dXgNsaokW4QDKWFhl0Vqh+u8CtkrWFO0Mrztq11+PLw1b mNkHEiG7FLnRGXWATuwUdq9ueS6gl0qa1PPacEa9iUiEk6/SPmNdMEmIT ykn/D2Oz9o+aufQH1VRFEEWGYJIHEtn4aO4ZowwAT8tYIP/ViVzR9d0qD K0IQn108sQmWMj15FhItHpc0AyJjJ8bzcdQfaQ6wNCbd3wTQVD6pV/E45 wO8hQD9kMUv4k2dYnsgmXqdGbQbxAgM+lcJ5XkZMsl+5cqj9K7qdOUfaV w==; X-IronPort-AV: E=McAfee;i="6600,9927,10803"; a="375312759" X-IronPort-AV: E=Sophos;i="6.01,177,1684825200"; d="scan'208";a="375312759" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Aug 2023 07:09:24 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10803"; a="980753051" X-IronPort-AV: E=Sophos;i="6.01,177,1684825200"; d="scan'208";a="980753051" Received: from irvmail002.ir.intel.com ([10.43.11.120]) by fmsmga006.fm.intel.com with ESMTP; 16 Aug 2023 07:09:21 -0700 Received: from pelor.igk.intel.com (pelor.igk.intel.com [10.123.220.13]) by irvmail002.ir.intel.com (Postfix) with ESMTP id E171234EE8; Wed, 16 Aug 2023 15:09:20 +0100 (IST) From: Przemek Kitszel To: Kees Cook , netdev@vger.kernel.org Cc: Jacob Keller , intel-wired-lan@lists.osuosl.org, Alexander Lobakin , linux-hardening@vger.kernel.org, Steven Zou , Przemek Kitszel Subject: [PATCH net-next v3 1/7] overflow: add DEFINE_FLEX() for on-stack allocs Date: Wed, 16 Aug 2023 10:06:17 -0400 Message-Id: <20230816140623.452869-2-przemyslaw.kitszel@intel.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230816140623.452869-1-przemyslaw.kitszel@intel.com> References: <20230816140623.452869-1-przemyslaw.kitszel@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org Add DEFINE_FLEX() macro for on-stack allocations of structs with flexible array member. Expose __struct_size() macro outside of fortify-string.h, as it could be used to read size of structs allocated by DEFINE_FLEX(). Move __member_size() alongside it. -Kees Using underlying array for on-stack storage lets us to declare known-at-compile-time structures without kzalloc(). Actual usage for ice driver is in following patches of the series. Missing __has_builtin() workaround is moved up to serve also assembly compilation with m68k-linux-gcc, see [1]. Error was (note the .S file extension): In file included from ../include/linux/linkage.h:5, from ../arch/m68k/fpsp040/skeleton.S:40: ../include/linux/compiler_types.h:331:5: warning: "__has_builtin" is not defined, evaluates to 0 [-Wundef] 331 | #if __has_builtin(__builtin_dynamic_object_size) | ^~~~~~~~~~~~~ ../include/linux/compiler_types.h:331:18: error: missing binary operator before token "(" 331 | #if __has_builtin(__builtin_dynamic_object_size) | ^ [1] https://lore.kernel.org/netdev/202308112122.OuF0YZqL-lkp@intel.com/ Co-developed-by: Kees Cook Signed-off-by: Kees Cook Signed-off-by: Przemek Kitszel Acked-by: Kees Cook --- v3: remove old macro needlessly kept in v2; fix build warning; reword doc comment; v2: Kees: reuse __struct_size() instead of adding new macro (adding Kees as Co-dev here); v1: change macro name; add macro for size read; accept struct type instead of ptr to it; change alignment; --- include/linux/compiler_types.h | 32 +++++++++++++++++++++----------- include/linux/fortify-string.h | 4 ---- include/linux/overflow.h | 20 ++++++++++++++++++++ 3 files changed, 41 insertions(+), 15 deletions(-) diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index 547ea1ff806e..f706691fc5b9 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -2,6 +2,15 @@ #ifndef __LINUX_COMPILER_TYPES_H #define __LINUX_COMPILER_TYPES_H +/* + * __has_builtin is supported on gcc >= 10, clang >= 3 and icc >= 21. + * In the meantime, to support gcc < 10, we implement __has_builtin + * by hand. + */ +#ifndef __has_builtin +#define __has_builtin(x) (0) +#endif + #ifndef __ASSEMBLY__ /* @@ -106,17 +115,6 @@ static inline void __chk_io_ptr(const volatile void __iomem *ptr) { } #define __cold #endif -/* Builtins */ - -/* - * __has_builtin is supported on gcc >= 10, clang >= 3 and icc >= 21. - * In the meantime, to support gcc < 10, we implement __has_builtin - * by hand. - */ -#ifndef __has_builtin -#define __has_builtin(x) (0) -#endif - /* Compiler specific macros. */ #ifdef __clang__ #include @@ -324,6 +322,18 @@ struct ftrace_likely_data { # define __realloc_size(x, ...) #endif +/* + * When the size of an allocated object is needed, use the best available + * mechanism to find it. (For cases where sizeof() cannot be used.) + */ +#if __has_builtin(__builtin_dynamic_object_size) +#define __struct_size(p) __builtin_dynamic_object_size(p, 0) +#define __member_size(p) __builtin_dynamic_object_size(p, 1) +#else +#define __struct_size(p) __builtin_object_size(p, 0) +#define __member_size(p) __builtin_object_size(p, 1) +#endif + #ifndef asm_volatile_goto #define asm_volatile_goto(x...) asm goto(x) #endif diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h index da51a83b2829..1e7711185ec6 100644 --- a/include/linux/fortify-string.h +++ b/include/linux/fortify-string.h @@ -93,13 +93,9 @@ extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) #if __has_builtin(__builtin_dynamic_object_size) #define POS __pass_dynamic_object_size(1) #define POS0 __pass_dynamic_object_size(0) -#define __struct_size(p) __builtin_dynamic_object_size(p, 0) -#define __member_size(p) __builtin_dynamic_object_size(p, 1) #else #define POS __pass_object_size(1) #define POS0 __pass_object_size(0) -#define __struct_size(p) __builtin_object_size(p, 0) -#define __member_size(p) __builtin_object_size(p, 1) #endif #define __compiletime_lessthan(bounds, length) ( \ diff --git a/include/linux/overflow.h b/include/linux/overflow.h index f9b60313eaea..34de97ea9e8e 100644 --- a/include/linux/overflow.h +++ b/include/linux/overflow.h @@ -309,4 +309,24 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend) #define struct_size_t(type, member, count) \ struct_size((type *)NULL, member, count) +/** + * DEFINE_FLEX() - Define an on-stack instance of structure with a trailing + * flexible array member. + * + * @type: structure type name, including "struct" keyword. + * @name: Name for a variable to define. + * @member: Name of the array member. + * @count: Number of elements in the array; must be compile-time const. + * + * Define a zeroed, on-stack, instance of @type structure with a trailing + * flexible array member. + * Use __struct_size(@name) to get compile-time size of it afterwards. + */ +#define DEFINE_FLEX(type, name, member, count) \ + union { \ + u8 bytes[struct_size_t(type, member, count)]; \ + type obj; \ + } name##_u __aligned(_Alignof(type)) = {}; \ + type *name = (type *)&name##_u + #endif /* __LINUX_OVERFLOW_H */