From patchwork Tue Feb 2 13:37:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 375278 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=-18.7 required=3.0 tests=BAYES_00,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 autolearn=ham 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 2AF11C433DB for ; Tue, 2 Feb 2021 14:01:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E3ABB64E7B for ; Tue, 2 Feb 2021 14:01:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233424AbhBBOBY (ORCPT ); Tue, 2 Feb 2021 09:01:24 -0500 Received: from mail.kernel.org ([198.145.29.99]:46314 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233544AbhBBN7V (ORCPT ); Tue, 2 Feb 2021 08:59:21 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 230B264FEF; Tue, 2 Feb 2021 13:46:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1612273573; bh=V+qjLziZGt2v9LS4/iEvp3So9Gqd5wEfy7zca1lFNVo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CB3kFQCS0PKT4cvT7aygoA6vQKy9vz4U4h5c6wAlQxmvdwwRlH/mT5GBhMIcAPJvq E1HlX+BxvtQf8iZnlc55cvq7A4N2TmBpCNtrwQunZRrZuuftd7Ijjt3ZutcBriprNG OCiHIWTYPgUf/Zs+b9yi/PxefzpEny9m7YCxM/GE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hangbin Liu , Jakub Kicinski , Aviraj CJ Subject: [PATCH 5.4 02/61] IPv6: reply ICMP error if the first fragment dont include all headers Date: Tue, 2 Feb 2021 14:37:40 +0100 Message-Id: <20210202132946.588647725@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210202132946.480479453@linuxfoundation.org> References: <20210202132946.480479453@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@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 Signed-off-by: Greg Kroah-Hartman --- net/ipv6/icmp.c | 8 +++++++- net/ipv6/reassembly.c | 33 ++++++++++++++++++++++++++++++++- 2 files changed, 39 insertions(+), 2 deletions(-) --- a/net/ipv6/icmp.c +++ b/net/ipv6/icmp.c @@ -158,7 +158,13 @@ static bool is_ineligible(const struct s 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; --- 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 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 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) {