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=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 89B36C282CB for ; Mon, 4 Feb 2019 11:08:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 559C82075C for ; Mon, 4 Feb 2019 11:08:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549278502; bh=1m1pk6iEgsqfDS0+izzv0cgkAkrpYbzWhPUTFrxsmPk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=hhbUTYlD679r33S00gHVXnODTUK5mw7egLyIhx1+FtWfj/VhsUt7hTV4/UQ0771Ed PWgZz3SgvW2rtDCAdKtHTd0iqNYbdlUymWClBK28bvOTA7BSVwA/VNj8mJAIecKhOA r1h0KcPHZenNh4EoXyvN/JSqZhS/noiQFXcTuqgM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730408AbfBDKlz (ORCPT ); Mon, 4 Feb 2019 05:41:55 -0500 Received: from mail.kernel.org ([198.145.29.99]:39802 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730391AbfBDKlv (ORCPT ); Mon, 4 Feb 2019 05:41:51 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 81F7B217D6; Mon, 4 Feb 2019 10:41:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549276911; bh=1m1pk6iEgsqfDS0+izzv0cgkAkrpYbzWhPUTFrxsmPk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qB0senRVD6WbJz1atJBd1RYzbCC6HQVk89xh4jmCTsXvogxLtR5LHjdRv28mR73lp SLCgAoHSlg3E9jkc+IiUrgX4UywIq3PEdR1oQVEcHXq7Sw+PLLBymnvaye+VfymlC5 kFXyAuOcgzOvqsoRYypS9MT6NYMDwL7mZuApEMbY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "David S. Miller" , Peter Oskolkov , Eric Dumazet , Florian Westphal , Stephen Hemminger , Mao Wenan Subject: [PATCH 4.4 56/65] ip: discard IPv4 datagrams with overlapping segments. Date: Mon, 4 Feb 2019 11:36:49 +0100 Message-Id: <20190204103619.834813196@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190204103610.583715954@linuxfoundation.org> References: <20190204103610.583715954@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peter Oskolkov commit 7969e5c40dfd04799d4341f1b7cd266b6e47f227 upstream. This behavior is required in IPv6, and there is little need to tolerate overlapping fragments in IPv4. This change simplifies the code and eliminates potential DDoS attack vectors. Tested: ran ip_defrag selftest (not yet available uptream). Suggested-by: David S. Miller Signed-off-by: Peter Oskolkov Signed-off-by: Eric Dumazet Cc: Florian Westphal Acked-by: Stephen Hemminger Signed-off-by: David S. Miller Signed-off-by: Mao Wenan Signed-off-by: Greg Kroah-Hartman --- include/uapi/linux/snmp.h | 1 net/ipv4/ip_fragment.c | 73 ++++++++++++---------------------------------- net/ipv4/proc.c | 1 3 files changed, 22 insertions(+), 53 deletions(-) --- a/include/uapi/linux/snmp.h +++ b/include/uapi/linux/snmp.h @@ -55,6 +55,7 @@ enum IPSTATS_MIB_ECT1PKTS, /* InECT1Pkts */ IPSTATS_MIB_ECT0PKTS, /* InECT0Pkts */ IPSTATS_MIB_CEPKTS, /* InCEPkts */ + IPSTATS_MIB_REASM_OVERLAPS, /* ReasmOverlaps */ __IPSTATS_MIB_MAX }; --- a/net/ipv4/ip_fragment.c +++ b/net/ipv4/ip_fragment.c @@ -342,6 +342,7 @@ static int ip_frag_reinit(struct ipq *qp /* Add new segment to existing queue. */ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) { + struct net *net = container_of(qp->q.net, struct net, ipv4.frags); struct sk_buff *prev, *next; struct net_device *dev; unsigned int fragsize; @@ -422,60 +423,22 @@ static int ip_frag_queue(struct ipq *qp, } found: - /* We found where to put this one. Check for overlap with - * preceding fragment, and, if needed, align things so that - * any overlaps are eliminated. + /* RFC5722, Section 4, amended by Errata ID : 3089 + * When reassembling an IPv6 datagram, if + * one or more its constituent fragments is determined to be an + * overlapping fragment, the entire datagram (and any constituent + * fragments) MUST be silently discarded. + * + * We do the same here for IPv4. */ - if (prev) { - int i = (FRAG_CB(prev)->offset + prev->len) - offset; - - if (i > 0) { - offset += i; - err = -EINVAL; - if (end <= offset) - goto err; - err = -ENOMEM; - if (!pskb_pull(skb, i)) - goto err; - if (skb->ip_summed != CHECKSUM_UNNECESSARY) - skb->ip_summed = CHECKSUM_NONE; - } - } - - err = -ENOMEM; - - while (next && FRAG_CB(next)->offset < end) { - int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */ - - if (i < next->len) { - /* Eat head of the next overlapped fragment - * and leave the loop. The next ones cannot overlap. - */ - if (!pskb_pull(next, i)) - goto err; - FRAG_CB(next)->offset += i; - qp->q.meat -= i; - if (next->ip_summed != CHECKSUM_UNNECESSARY) - next->ip_summed = CHECKSUM_NONE; - break; - } else { - struct sk_buff *free_it = next; - - /* Old fragment is completely overridden with - * new one drop it. - */ - next = next->next; - - if (prev) - prev->next = next; - else - qp->q.fragments = next; - - qp->q.meat -= free_it->len; - sub_frag_mem_limit(qp->q.net, free_it->truesize); - kfree_skb(free_it); - } - } + /* Is there an overlap with the previous fragment? */ + if (prev && + (FRAG_CB(prev)->offset + prev->len) > offset) + goto discard_qp; + + /* Is there an overlap with the next fragment? */ + if (next && FRAG_CB(next)->offset < end) + goto discard_qp; FRAG_CB(skb)->offset = offset; @@ -522,6 +485,10 @@ found: skb_dst_drop(skb); return -EINPROGRESS; +discard_qp: + ipq_kill(qp); + err = -EINVAL; + IP_INC_STATS(net, IPSTATS_MIB_REASM_OVERLAPS); err: kfree_skb(skb); return err; --- a/net/ipv4/proc.c +++ b/net/ipv4/proc.c @@ -132,6 +132,7 @@ static const struct snmp_mib snmp4_ipext SNMP_MIB_ITEM("InECT1Pkts", IPSTATS_MIB_ECT1PKTS), SNMP_MIB_ITEM("InECT0Pkts", IPSTATS_MIB_ECT0PKTS), SNMP_MIB_ITEM("InCEPkts", IPSTATS_MIB_CEPKTS), + SNMP_MIB_ITEM("ReasmOverlaps", IPSTATS_MIB_REASM_OVERLAPS), SNMP_MIB_SENTINEL };