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=-15.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 EF83DC4338F for ; Wed, 28 Jul 2021 06:34:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D97E8601FE for ; Wed, 28 Jul 2021 06:34:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234862AbhG1Ge6 (ORCPT ); Wed, 28 Jul 2021 02:34:58 -0400 Received: from gateway23.websitewelcome.com ([192.185.50.129]:43284 "EHLO gateway23.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234836AbhG1Ge5 (ORCPT ); Wed, 28 Jul 2021 02:34:57 -0400 X-Greylist: delayed 367 seconds by postgrey-1.27 at vger.kernel.org; Wed, 28 Jul 2021 02:34:56 EDT Received: from cm13.websitewelcome.com (cm13.websitewelcome.com [100.42.49.6]) by gateway23.websitewelcome.com (Postfix) with ESMTP id ADAEFABAA for ; Wed, 28 Jul 2021 01:12:11 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 8cnbmSHGIrJtZ8cnbmD0TZ; Wed, 28 Jul 2021 01:12:11 -0500 X-Authority-Reason: nr=8 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=embeddedor.com; s=default; h=Content-Transfer-Encoding:Content-Type: In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Subject:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=/gCRywG3p9gdzDsdnfCiyJuRt7hlhcIRTlf1DfYGxQk=; b=VcIfYrm9dG72K/ZQdtfuvuRlxT V3vj8YAhGaZx/cGjli4zOBFYlJLoXo0Vsd02K5fRjcNQP9NIaIESg+YOXV99qTCB2Yo/O/8WHP1ds tXZbD1nJiwP3eEvBBTiZUo+VuIrDMlwm0ktVaXENnRTX4JuI9vlmD7ltgDRPbsHiRknznvoYhhE9n E8MtFRCudEt5DeNW0MrlXGslPCSnGcfJ5OUAGOu7TVmX7V7cwyVfPVrDjuE3onf3wAwUBuIo0NmMx IpJTghBwcX95Gj2Ml9t6eR6MSITfuKehPikhPibC8RrQ3I91RzhVBZtQ0/pRauPtwPnnaJk7AevGt aQE41uZw==; Received: from 187-162-31-110.static.axtel.net ([187.162.31.110]:44814 helo=[192.168.15.8]) by gator4166.hostgator.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1m8cna-003PI6-Vi; Wed, 28 Jul 2021 01:12:11 -0500 Subject: Re: [PATCH 19/64] ip: Use struct_group() for memcpy() regions To: Greg Kroah-Hartman , Kees Cook Cc: linux-hardening@vger.kernel.org, "Gustavo A. R. Silva" , Keith Packard , Andrew Morton , linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-staging@lists.linux.dev, linux-block@vger.kernel.org, linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com References: <20210727205855.411487-1-keescook@chromium.org> <20210727205855.411487-20-keescook@chromium.org> From: "Gustavo A. R. Silva" Message-ID: Date: Wed, 28 Jul 2021 01:14:33 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 187.162.31.110 X-Source-L: No X-Exim-ID: 1m8cna-003PI6-Vi X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: 187-162-31-110.static.axtel.net ([192.168.15.8]) [187.162.31.110]:44814 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 8 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On 7/28/21 00:55, Greg Kroah-Hartman wrote: > On Tue, Jul 27, 2021 at 01:58:10PM -0700, Kees Cook wrote: >> In preparation for FORTIFY_SOURCE performing compile-time and run-time >> field bounds checking for memcpy(), memmove(), and memset(), avoid >> intentionally writing across neighboring fields. >> >> Use struct_group() in struct flowi4, struct ipv4hdr, and struct ipv6hdr >> around members saddr and daddr, so they can be referenced together. This >> will allow memcpy() and sizeof() to more easily reason about sizes, >> improve readability, and avoid future warnings about writing beyond the >> end of saddr. >> >> "pahole" shows no size nor member offset changes to struct flowi4. >> "objdump -d" shows no meaningful object code changes (i.e. only source >> line number induced differences.) >> >> Note that since this is a UAPI header, struct_group() has been open >> coded. >> >> Signed-off-by: Kees Cook >> --- >> include/net/flow.h | 6 ++++-- >> include/uapi/linux/if_ether.h | 12 ++++++++++-- >> include/uapi/linux/ip.h | 12 ++++++++++-- >> include/uapi/linux/ipv6.h | 12 ++++++++++-- >> net/core/flow_dissector.c | 10 ++++++---- >> net/ipv4/ip_output.c | 6 ++---- >> 6 files changed, 42 insertions(+), 16 deletions(-) >> >> diff --git a/include/net/flow.h b/include/net/flow.h >> index 6f5e70240071..f1a3b6c8eae2 100644 >> --- a/include/net/flow.h >> +++ b/include/net/flow.h >> @@ -81,8 +81,10 @@ struct flowi4 { >> #define flowi4_multipath_hash __fl_common.flowic_multipath_hash >> >> /* (saddr,daddr) must be grouped, same order as in IP header */ >> - __be32 saddr; >> - __be32 daddr; >> + struct_group(addrs, >> + __be32 saddr; >> + __be32 daddr; >> + ); >> >> union flowi_uli uli; >> #define fl4_sport uli.ports.sport >> diff --git a/include/uapi/linux/if_ether.h b/include/uapi/linux/if_ether.h >> index a0b637911d3c..8f5667b2ea92 100644 >> --- a/include/uapi/linux/if_ether.h >> +++ b/include/uapi/linux/if_ether.h >> @@ -163,8 +163,16 @@ >> >> #if __UAPI_DEF_ETHHDR >> struct ethhdr { >> - unsigned char h_dest[ETH_ALEN]; /* destination eth addr */ >> - unsigned char h_source[ETH_ALEN]; /* source ether addr */ >> + union { >> + struct { >> + unsigned char h_dest[ETH_ALEN]; /* destination eth addr */ >> + unsigned char h_source[ETH_ALEN]; /* source ether addr */ >> + }; >> + struct { >> + unsigned char h_dest[ETH_ALEN]; /* destination eth addr */ >> + unsigned char h_source[ETH_ALEN]; /* source ether addr */ >> + } addrs; > > A union of the same fields in the same structure in the same way? > > Ah, because struct_group() can not be used here? Still feels odd to see > in a userspace-visible header. > >> + }; >> __be16 h_proto; /* packet type ID field */ >> } __attribute__((packed)); >> #endif >> diff --git a/include/uapi/linux/ip.h b/include/uapi/linux/ip.h >> index e42d13b55cf3..33647a37e56b 100644 >> --- a/include/uapi/linux/ip.h >> +++ b/include/uapi/linux/ip.h >> @@ -100,8 +100,16 @@ struct iphdr { >> __u8 ttl; >> __u8 protocol; >> __sum16 check; >> - __be32 saddr; >> - __be32 daddr; >> + union { >> + struct { >> + __be32 saddr; >> + __be32 daddr; >> + } addrs; >> + struct { >> + __be32 saddr; >> + __be32 daddr; >> + }; > > Same here (except you named the first struct addrs, not the second, > unlike above). > > >> + }; >> /*The options start here. */ >> }; >> >> diff --git a/include/uapi/linux/ipv6.h b/include/uapi/linux/ipv6.h >> index b243a53fa985..1c26d32e733b 100644 >> --- a/include/uapi/linux/ipv6.h >> +++ b/include/uapi/linux/ipv6.h >> @@ -130,8 +130,16 @@ struct ipv6hdr { >> __u8 nexthdr; >> __u8 hop_limit; >> >> - struct in6_addr saddr; >> - struct in6_addr daddr; >> + union { >> + struct { >> + struct in6_addr saddr; >> + struct in6_addr daddr; >> + } addrs; >> + struct { >> + struct in6_addr saddr; >> + struct in6_addr daddr; >> + }; > > addrs first? Consistancy is key :) I think addrs should be second. In general, I think all newly added non-anonymous structures should be second. Thanks -- Gustavo