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=-20.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,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 E896AC4338F for ; Wed, 28 Jul 2021 06:53:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BF7A460C3F for ; Wed, 28 Jul 2021 06:53:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229560AbhG1Gxn (ORCPT ); Wed, 28 Jul 2021 02:53:43 -0400 Received: from gateway24.websitewelcome.com ([192.185.50.84]:30656 "EHLO gateway24.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234919AbhG1Gxm (ORCPT ); Wed, 28 Jul 2021 02:53:42 -0400 Received: from cm17.websitewelcome.com (cm17.websitewelcome.com [100.42.49.20]) by gateway24.websitewelcome.com (Postfix) with ESMTP id C019B5CC2 for ; Wed, 28 Jul 2021 01:28:47 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 8d3fmtFcgMGeE8d3fmFjix; Wed, 28 Jul 2021 01:28:47 -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=PByFd2qeq/2ftWrrzQXYKD+9AqEh75xYa8NQ7nHf9Jg=; b=xWCSVCo5rpt31TLlsry/YUFajz 3jA2mTLH4KNhe9tI4XkYLKH0Xy21oqpA5P6w/Hwo/OcuoqKAXGFZf2G6+6KKiYg2U+aWtrrV9w+ML ApF9qrFmxonjwBRtuuEVSY7bc0Jokt/psPrr/ZHtbnAqHtnjZKzLZthWhSuUihdf2niFgsXWm2HSF Unvkjsr3dhsaSdMUrDx/7+A3BJKmlMCmHl+LGrHCrUnwaU5QVdXc9IqcmgBcb+kOsNp8bVhSDimG8 6bMVBYBFra3XQQn5NT/BaDR1PfSNheKjyXXpQf0+fPK2zlnoWClN40rqV6WLCNHkAbgUOHdGDkF0W bUURrNIA==; Received: from 187-162-31-110.static.axtel.net ([187.162.31.110]:44898 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 1m8d3e-003ign-Vl; Wed, 28 Jul 2021 01:28:47 -0500 Subject: Re: [PATCH 19/64] ip: Use struct_group() for memcpy() regions To: Greg Kroah-Hartman Cc: Kees Cook , 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 01:31:16 -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: 1m8d3e-003ign-Vl 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]:44898 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 22 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On 7/28/21 01:19, Greg Kroah-Hartman wrote: > On Wed, Jul 28, 2021 at 01:14:33AM -0500, Gustavo A. R. Silva wrote: >> >> >> 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. > > Why not use a local version of the macro like was done in the DRM header > file, to make it always work the same and more obvious what is > happening? If I were a userspace developer and saw the above, I would > think that the kernel developers have lost it :) Then don't take a look at this[1]. :p -- Gustavo [1] https://git.kernel.org/linus/c0a744dcaa29e9537e8607ae9c965ad936124a4d