From patchwork Fri Jan 29 19:27:41 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Aviraj CJ X-Patchwork-Id: 373682 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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT, USER_IN_DEF_DKIM_WL 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 651C9C433DB for ; Fri, 29 Jan 2021 19:39:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1221C64DE9 for ; Fri, 29 Jan 2021 19:39:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233025AbhA2Tic (ORCPT ); Fri, 29 Jan 2021 14:38:32 -0500 Received: from bgl-iport-4.cisco.com ([72.163.197.28]:7414 "EHLO bgl-iport-4.cisco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232752AbhA2Tia (ORCPT ); Fri, 29 Jan 2021 14:38:30 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cisco.com; i=@cisco.com; l=3911; q=dns/txt; s=iport; t=1611949108; x=1613158708; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=8T6xhh/+97MYL69HOZHijmar/RuLTo27yNHNS+EKjJA=; b=WiGPGAOZKyws+5k6txWJ9KIAlQVxbdK9h/Ci35OBlUxAfwK7Kb9qsd1q vp006ykzO+fwZr22yiUoRXzL+McRMnCq7E2yqYu6Cy5z9WNbwN5IKF/Q5 wSxLXHIhav77V7rVwWGmRaEQojlutGjXALthNIGPGvaUXgj6bRdVIItYv 4=; X-IronPort-AV: E=Sophos;i="5.79,386,1602547200"; d="scan'208";a="175655162" Received: from vla196-nat.cisco.com (HELO bgl-core-4.cisco.com) ([72.163.197.24]) by bgl-iport-4.cisco.com with ESMTP/TLS/DHE-RSA-SEED-SHA; 29 Jan 2021 19:28:13 +0000 Received: from bgl-ads-1848.cisco.com (bgl-ads-1848.cisco.com [173.39.51.250]) by bgl-core-4.cisco.com (8.15.2/8.15.2) with ESMTPS id 10TJSCZL010736 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Fri, 29 Jan 2021 19:28:12 GMT Received: by bgl-ads-1848.cisco.com (Postfix, from userid 838444) id 6A207CC1251; Sat, 30 Jan 2021 00:58:12 +0530 (IST) From: Aviraj CJ To: davem@davemloft.net, kuznet@ms2.inr.ac.ru, yoshfuji@linux-ipv6.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, xe-linux-external@cisco.com, acj@cisco.com Cc: Hangbin Liu , Jakub Kicinski Subject: [Internal review][PATCH stable v5.4 2/2] IPv6: reply ICMP error if the first fragment don't include all headers Date: Sat, 30 Jan 2021 00:57:41 +0530 Message-Id: <20210129192741.117693-2-acj@cisco.com> X-Mailer: git-send-email 2.26.2.Cisco In-Reply-To: <20210129192741.117693-1-acj@cisco.com> References: <20210129192741.117693-1-acj@cisco.com> MIME-Version: 1.0 X-Auto-Response-Suppress: DR, OOF, AutoReply X-Outbound-SMTP-Client: 173.39.51.250, bgl-ads-1848.cisco.com X-Outbound-Node: bgl-core-4.cisco.com Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Hangbin Liu commit 2efdaaaf883a143061296467913c01aa1ff4b3ce upstream. Based on RFC 8200, Section 4.5 Fragment Header: - If the first fragment does not include all headers through an Upper-Layer header, then that fragment should be discarded and an ICMP Parameter Problem, Code 3, message should be sent to the source of the fragment, with the Pointer field set to zero. Checking each packet header in IPv6 fast path will have performance impact, so I put the checking in ipv6_frag_rcv(). As the packet may be any kind of L4 protocol, I only checked some common protocols' header length and handle others by (offset + 1) > skb->len. Also use !(frag_off & htons(IP6_OFFSET)) to catch atomic fragments (fragmented packet with only one fragment). When send ICMP error message, if the 1st truncated fragment is ICMP message, icmp6_send() will break as is_ineligible() return true. So I added a check in is_ineligible() to let fragment packet with nexthdr ICMP but no ICMP header return false. Signed-off-by: Hangbin Liu Signed-off-by: Jakub Kicinski Signed-off-by: Aviraj CJ --- net/ipv6/icmp.c | 8 +++++++- net/ipv6/reassembly.c | 33 ++++++++++++++++++++++++++++++++- 2 files changed, 39 insertions(+), 2 deletions(-) diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c index 7d3a3894f785..e9bb89131e02 100644 --- a/net/ipv6/icmp.c +++ b/net/ipv6/icmp.c @@ -158,7 +158,13 @@ static bool is_ineligible(const struct sk_buff *skb) tp = skb_header_pointer(skb, ptr+offsetof(struct icmp6hdr, icmp6_type), sizeof(_type), &_type); - if (!tp || !(*tp & ICMPV6_INFOMSG_MASK)) + + /* Based on RFC 8200, Section 4.5 Fragment Header, return + * false if this is a fragment packet with no icmp header info. + */ + if (!tp && frag_off != 0) + return false; + else if (!tp || !(*tp & ICMPV6_INFOMSG_MASK)) return true; } return false; diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c index 1f5d4d196dcc..c8cf1bbad74a 100644 --- a/net/ipv6/reassembly.c +++ b/net/ipv6/reassembly.c @@ -42,6 +42,8 @@ #include #include #include +#include +#include #include #include @@ -322,7 +324,9 @@ static int ipv6_frag_rcv(struct sk_buff *skb) struct frag_queue *fq; const struct ipv6hdr *hdr = ipv6_hdr(skb); struct net *net = dev_net(skb_dst(skb)->dev); - int iif; + __be16 frag_off; + int iif, offset; + u8 nexthdr; if (IP6CB(skb)->flags & IP6SKB_FRAGMENTED) goto fail_hdr; @@ -351,6 +355,33 @@ static int ipv6_frag_rcv(struct sk_buff *skb) return 1; } + /* RFC 8200, Section 4.5 Fragment Header: + * If the first fragment does not include all headers through an + * Upper-Layer header, then that fragment should be discarded and + * an ICMP Parameter Problem, Code 3, message should be sent to + * the source of the fragment, with the Pointer field set to zero. + */ + nexthdr = hdr->nexthdr; + offset = ipv6_skip_exthdr(skb, skb_transport_offset(skb), &nexthdr, &frag_off); + if (offset >= 0) { + /* Check some common protocols' header */ + if (nexthdr == IPPROTO_TCP) + offset += sizeof(struct tcphdr); + else if (nexthdr == IPPROTO_UDP) + offset += sizeof(struct udphdr); + else if (nexthdr == IPPROTO_ICMPV6) + offset += sizeof(struct icmp6hdr); + else + offset += 1; + + if (!(frag_off & htons(IP6_OFFSET)) && offset > skb->len) { + __IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev), + IPSTATS_MIB_INHDRERRORS); + icmpv6_param_prob(skb, ICMPV6_HDR_INCOMP, 0); + return -1; + } + } + iif = skb->dev ? skb->dev->ifindex : 0; fq = fq_find(net, fhdr->identification, hdr, iif); if (fq) {