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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, 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=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 424B7C11F66 for ; Mon, 12 Jul 2021 08:52:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3022F60FF1 for ; Mon, 12 Jul 2021 08:52:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1380350AbhGLIvc (ORCPT ); Mon, 12 Jul 2021 04:51:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:44678 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348844AbhGLH4M (ORCPT ); Mon, 12 Jul 2021 03:56:12 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 24F2F61364; Mon, 12 Jul 2021 07:52:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626076330; bh=Fw05bfOcbeB/ybrzfS9W6cn9jZP8sO8CxhgD6UzLo+4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=csBmp+DdoMhaYrON92e1+dKNoCzRe5aMgO6AH/vJtfYnojfH4ZJbIDKiRvhWycye1 Kgg8ps1MynaVrOEdVryk7PcYz01hJkjz9dsRvduWKJJ1LNiekWh5Pko7jk3jB+a1W2 vi/TZhLAMhlKZOmSvdWE0cM7UCGZ3eMdUaKVIrqg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, David Ahern , Vadim Fedorenko , David Ahern , "David S. Miller" , Sasha Levin Subject: [PATCH 5.13 596/800] net: lwtunnel: handle MTU calculation in forwading Date: Mon, 12 Jul 2021 08:10:19 +0200 Message-Id: <20210712061030.725042613@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210712060912.995381202@linuxfoundation.org> References: <20210712060912.995381202@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Vadim Fedorenko [ Upstream commit fade56410c22cacafb1be9f911a0afd3701d8366 ] Commit 14972cbd34ff ("net: lwtunnel: Handle fragmentation") moved fragmentation logic away from lwtunnel by carry encap headroom and use it in output MTU calculation. But the forwarding part was not covered and created difference in MTU for output and forwarding and further to silent drops on ipv4 forwarding path. Fix it by taking into account lwtunnel encap headroom. The same commit also introduced difference in how to treat RTAX_MTU in IPv4 and IPv6 where latter explicitly removes lwtunnel encap headroom from route MTU. Make IPv4 version do the same. Fixes: 14972cbd34ff ("net: lwtunnel: Handle fragmentation") Suggested-by: David Ahern Signed-off-by: Vadim Fedorenko Reviewed-by: David Ahern Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- include/net/ip.h | 12 ++++++++---- include/net/ip6_route.h | 16 ++++++++++++---- net/ipv4/route.c | 3 ++- 3 files changed, 22 insertions(+), 9 deletions(-) diff --git a/include/net/ip.h b/include/net/ip.h index e20874059f82..d9683bef8684 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -31,6 +31,7 @@ #include #include #include +#include #define IPV4_MAX_PMTU 65535U /* RFC 2675, Section 5.1 */ #define IPV4_MIN_MTU 68 /* RFC 791 */ @@ -445,22 +446,25 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst, /* 'forwarding = true' case should always honour route mtu */ mtu = dst_metric_raw(dst, RTAX_MTU); - if (mtu) - return mtu; + if (!mtu) + mtu = min(READ_ONCE(dst->dev->mtu), IP_MAX_MTU); - return min(READ_ONCE(dst->dev->mtu), IP_MAX_MTU); + return mtu - lwtunnel_headroom(dst->lwtstate, mtu); } static inline unsigned int ip_skb_dst_mtu(struct sock *sk, const struct sk_buff *skb) { + unsigned int mtu; + if (!sk || !sk_fullsock(sk) || ip_sk_use_pmtu(sk)) { bool forwarding = IPCB(skb)->flags & IPSKB_FORWARDED; return ip_dst_mtu_maybe_forward(skb_dst(skb), forwarding); } - return min(READ_ONCE(skb_dst(skb)->dev->mtu), IP_MAX_MTU); + mtu = min(READ_ONCE(skb_dst(skb)->dev->mtu), IP_MAX_MTU); + return mtu - lwtunnel_headroom(skb_dst(skb)->lwtstate, mtu); } struct dst_metrics *ip_fib_metrics_init(struct net *net, struct nlattr *fc_mx, diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h index f51a118bfce8..f14149df5a65 100644 --- a/include/net/ip6_route.h +++ b/include/net/ip6_route.h @@ -265,11 +265,18 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, static inline int ip6_skb_dst_mtu(struct sk_buff *skb) { + int mtu; + struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ? inet6_sk(skb->sk) : NULL; - return (np && np->pmtudisc >= IPV6_PMTUDISC_PROBE) ? - skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb)); + if (np && np->pmtudisc >= IPV6_PMTUDISC_PROBE) { + mtu = READ_ONCE(skb_dst(skb)->dev->mtu); + mtu -= lwtunnel_headroom(skb_dst(skb)->lwtstate, mtu); + } else + mtu = dst_mtu(skb_dst(skb)); + + return mtu; } static inline bool ip6_sk_accept_pmtu(const struct sock *sk) @@ -317,7 +324,7 @@ static inline unsigned int ip6_dst_mtu_forward(const struct dst_entry *dst) if (dst_metric_locked(dst, RTAX_MTU)) { mtu = dst_metric_raw(dst, RTAX_MTU); if (mtu) - return mtu; + goto out; } mtu = IPV6_MIN_MTU; @@ -327,7 +334,8 @@ static inline unsigned int ip6_dst_mtu_forward(const struct dst_entry *dst) mtu = idev->cnf.mtu6; rcu_read_unlock(); - return mtu; +out: + return mtu - lwtunnel_headroom(dst->lwtstate, mtu); } u32 ip6_mtu_from_fib6(const struct fib6_result *res, diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 6a36ac98476f..78d1e5afc452 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1306,7 +1306,7 @@ INDIRECT_CALLABLE_SCOPE unsigned int ipv4_mtu(const struct dst_entry *dst) mtu = dst_metric_raw(dst, RTAX_MTU); if (mtu) - return mtu; + goto out; mtu = READ_ONCE(dst->dev->mtu); @@ -1315,6 +1315,7 @@ INDIRECT_CALLABLE_SCOPE unsigned int ipv4_mtu(const struct dst_entry *dst) mtu = 576; } +out: mtu = min_t(unsigned int, mtu, IP_MAX_MTU); return mtu - lwtunnel_headroom(dst->lwtstate, mtu); -- 2.30.2