From patchwork Wed Mar 9 13:08:35 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steffen Klassert X-Patchwork-Id: 12775052 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4048BC433EF for ; Wed, 9 Mar 2022 13:08:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232973AbiCINJx (ORCPT ); Wed, 9 Mar 2022 08:09:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44774 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232473AbiCINJt (ORCPT ); Wed, 9 Mar 2022 08:09:49 -0500 Received: from a.mx.secunet.com (a.mx.secunet.com [62.96.220.36]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4793CC8FA0 for ; Wed, 9 Mar 2022 05:08:50 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by a.mx.secunet.com (Postfix) with ESMTP id F384C2019D; Wed, 9 Mar 2022 14:08:48 +0100 (CET) X-Virus-Scanned: by secunet Received: from a.mx.secunet.com ([127.0.0.1]) by localhost (a.mx.secunet.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id DRINu8tKeVQc; Wed, 9 Mar 2022 14:08:42 +0100 (CET) Received: from mailout2.secunet.com (mailout2.secunet.com [62.96.220.49]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by a.mx.secunet.com (Postfix) with ESMTPS id 965332009B; Wed, 9 Mar 2022 14:08:42 +0100 (CET) Received: from cas-essen-02.secunet.de (unknown [10.53.40.202]) by mailout2.secunet.com (Postfix) with ESMTP id 8F0E480004A; Wed, 9 Mar 2022 14:08:42 +0100 (CET) Received: from mbx-essen-01.secunet.de (10.53.40.197) by cas-essen-02.secunet.de (10.53.40.202) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.18; Wed, 9 Mar 2022 14:08:42 +0100 Received: from gauss2.secunet.de (10.182.7.193) by mbx-essen-01.secunet.de (10.53.40.197) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.18; Wed, 9 Mar 2022 14:08:41 +0100 Received: by gauss2.secunet.de (Postfix, from userid 1000) id 9DADA3180625; Wed, 9 Mar 2022 14:08:41 +0100 (CET) From: Steffen Klassert To: David Miller , Jakub Kicinski CC: Herbert Xu , Steffen Klassert , Subject: [PATCH 1/5] xfrm: fix tunnel model fragmentation behavior Date: Wed, 9 Mar 2022 14:08:35 +0100 Message-ID: <20220309130839.3263912-2-steffen.klassert@secunet.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220309130839.3263912-1-steffen.klassert@secunet.com> References: <20220309130839.3263912-1-steffen.klassert@secunet.com> MIME-Version: 1.0 X-ClientProxiedBy: cas-essen-02.secunet.de (10.53.40.202) To mbx-essen-01.secunet.de (10.53.40.197) X-EXCLAIMER-MD-CONFIG: 2c86f778-e09b-4440-8b15-867914633a10 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org From: Lina Wang in tunnel mode, if outer interface(ipv4) is less, it is easily to let inner IPV6 mtu be less than 1280. If so, a Packet Too Big ICMPV6 message is received. When send again, packets are fragmentized with 1280, they are still rejected with ICMPV6(Packet Too Big) by xfrmi_xmit2(). According to RFC4213 Section3.2.2: if (IPv4 path MTU - 20) is less than 1280 if packet is larger than 1280 bytes Send ICMPv6 "packet too big" with MTU=1280 Drop packet else Encapsulate but do not set the Don't Fragment flag in the IPv4 header. The resulting IPv4 packet might be fragmented by the IPv4 layer on the encapsulator or by some router along the IPv4 path. endif else if packet is larger than (IPv4 path MTU - 20) Send ICMPv6 "packet too big" with MTU = (IPv4 path MTU - 20). Drop packet. else Encapsulate and set the Don't Fragment flag in the IPv4 header. endif endif Packets should be fragmentized with ipv4 outer interface, so change it. After it is fragemtized with ipv4, there will be double fragmenation. No.48 & No.51 are ipv6 fragment packets, No.48 is double fragmentized, then tunneled with IPv4(No.49& No.50), which obey spec. And received peer cannot decrypt it rightly. 48 2002::10 2002::11 1296(length) IPv6 fragment (off=0 more=y ident=0xa20da5bc nxt=50) 49 0x0000 (0) 2002::10 2002::11 1304 IPv6 fragment (off=0 more=y ident=0x7448042c nxt=44) 50 0x0000 (0) 2002::10 2002::11 200 ESP (SPI=0x00035000) 51 2002::10 2002::11 180 Echo (ping) request 52 0x56dc 2002::10 2002::11 248 IPv6 fragment (off=1232 more=n ident=0xa20da5bc nxt=50) xfrm6_noneed_fragment has fixed above issues. Finally, it acted like below: 1 0x6206 192.168.1.138 192.168.1.1 1316 Fragmented IP protocol (proto=Encap Security Payload 50, off=0, ID=6206) [Reassembled in #2] 2 0x6206 2002::10 2002::11 88 IPv6 fragment (off=0 more=y ident=0x1f440778 nxt=50) 3 0x0000 2002::10 2002::11 248 ICMPv6 Echo (ping) request Signed-off-by: Lina Wang Signed-off-by: Steffen Klassert --- net/ipv6/xfrm6_output.c | 16 ++++++++++++++++ net/xfrm/xfrm_interface.c | 5 ++++- 2 files changed, 20 insertions(+), 1 deletion(-) diff --git a/net/ipv6/xfrm6_output.c b/net/ipv6/xfrm6_output.c index d0d280077721..ad07904642ca 100644 --- a/net/ipv6/xfrm6_output.c +++ b/net/ipv6/xfrm6_output.c @@ -45,6 +45,19 @@ static int __xfrm6_output_finish(struct net *net, struct sock *sk, struct sk_buf return xfrm_output(sk, skb); } +static int xfrm6_noneed_fragment(struct sk_buff *skb) +{ + struct frag_hdr *fh; + u8 prevhdr = ipv6_hdr(skb)->nexthdr; + + if (prevhdr != NEXTHDR_FRAGMENT) + return 0; + fh = (struct frag_hdr *)(skb->data + sizeof(struct ipv6hdr)); + if (fh->nexthdr == NEXTHDR_ESP || fh->nexthdr == NEXTHDR_AUTH) + return 1; + return 0; +} + static int __xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb) { struct dst_entry *dst = skb_dst(skb); @@ -73,6 +86,9 @@ static int __xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb) xfrm6_local_rxpmtu(skb, mtu); kfree_skb(skb); return -EMSGSIZE; + } else if (toobig && xfrm6_noneed_fragment(skb)) { + skb->ignore_df = 1; + goto skip_frag; } else if (!skb->ignore_df && toobig && skb->sk) { xfrm_local_error(skb, mtu); kfree_skb(skb); diff --git a/net/xfrm/xfrm_interface.c b/net/xfrm/xfrm_interface.c index 4e3c62d1ad9e..1e8b26eecb3f 100644 --- a/net/xfrm/xfrm_interface.c +++ b/net/xfrm/xfrm_interface.c @@ -304,7 +304,10 @@ xfrmi_xmit2(struct sk_buff *skb, struct net_device *dev, struct flowi *fl) if (mtu < IPV6_MIN_MTU) mtu = IPV6_MIN_MTU; - icmpv6_ndo_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu); + if (skb->len > 1280) + icmpv6_ndo_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu); + else + goto xmit; } else { if (!(ip_hdr(skb)->frag_off & htons(IP_DF))) goto xmit;