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 8F832C282C2 for ; Thu, 7 Feb 2019 11:45:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 542902080F for ; Thu, 7 Feb 2019 11:45:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549539907; bh=eHKBfYoxOgh7HqC6fevUYoC3uJ6dzDnzXQnRQUk2T0A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ZhdHZAi9I7NGNhs8t9IpSRb1625sm7vJL6rwEkHXiKEq98Wbu5erLWi4HGrK6boRe tVnNZFw/nLAAn39hUGJ9P0nNWf8f5zemzytsFAOayGWe9VO0YkhcWUPwrMI382dzZO d0QxAvg+poXsdr66Lou4L7ERq2Ssqs9pDKx8/86U= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727308AbfBGLnG (ORCPT ); Thu, 7 Feb 2019 06:43:06 -0500 Received: from mail.kernel.org ([198.145.29.99]:33210 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727300AbfBGLnF (ORCPT ); Thu, 7 Feb 2019 06:43:05 -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 B3F5B21907; Thu, 7 Feb 2019 11:43:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549539784; bh=eHKBfYoxOgh7HqC6fevUYoC3uJ6dzDnzXQnRQUk2T0A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jrUxvZCcSKX+XlFljsDABt2Akm9O7x4JOBgvmiC2M8xs91aIKMkqPf6HcXzbTlJrJ 0KlXlrGOn5iqlR3NJ9Qb5hIH6RdxY8dJe5GNJZ1QEjj+5GQS+8+pbvByPpCroU6Uh8 hQ1Zd5Big58Ii/1Upao3OIVAhyDxsXtke7w5otrs= 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 , Ben Hutchings Subject: [PATCH 4.4 22/34] ip: discard IPv4 datagrams with overlapping segments. Date: Thu, 7 Feb 2019 12:42:04 +0100 Message-Id: <20190207113026.434645173@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190207113025.552605181@linuxfoundation.org> References: <20190207113025.552605181@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 [bwh: Backported to 4.4: - s/__IP_INC_STATS/IP_INC_STATS_BH/ - Deleted code is slightly different] Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- include/uapi/linux/snmp.h | 1 net/ipv4/ip_fragment.c | 72 ++++++++++++---------------------------------- net/ipv4/proc.c | 1 3 files changed, 22 insertions(+), 52 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 @@ -277,6 +277,7 @@ 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; @@ -357,60 +358,23 @@ 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 = (prev->ip_defrag_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 && next->ip_defrag_offset < end) { - int i = end - next->ip_defrag_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; - next->ip_defrag_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 && + (prev->ip_defrag_offset + prev->len) > offset) + goto discard_qp; + + /* Is there an overlap with the next fragment? */ + if (next && next->ip_defrag_offset < end) + goto discard_qp; /* Note : skb->ip_defrag_offset and skb->dev share the same location */ dev = skb->dev; @@ -458,6 +422,10 @@ found: skb_dst_drop(skb); return -EINPROGRESS; +discard_qp: + inet_frag_kill(&qp->q); + err = -EINVAL; + IP_INC_STATS_BH(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 };