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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 BDC5BC43387 for ; Wed, 16 Jan 2019 13:05:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 83572206C2 for ; Wed, 16 Jan 2019 13:05:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392968AbfAPNFZ (ORCPT ); Wed, 16 Jan 2019 08:05:25 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:2241 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2390247AbfAPNFZ (ORCPT ); Wed, 16 Jan 2019 08:05:25 -0500 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 4B482F6285499BE31433; Wed, 16 Jan 2019 21:05:22 +0800 (CST) Received: from localhost (10.177.24.66) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.408.0; Wed, 16 Jan 2019 21:05:12 +0800 From: wangyunjian To: CC: , Yunjian Wang , , Nkolay Aleksandrov , Roopa Prabhu Subject: [PATCH net v3] net: bridge: Fix ethernet header pointer before check skb forwardable Date: Wed, 16 Jan 2019 21:04:21 +0800 Message-ID: <1547643861-15340-1-git-send-email-wangyunjian@huawei.com> X-Mailer: git-send-email 1.9.5.msysgit.1 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.177.24.66] X-CFilter-Loop: Reflected Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Yunjian Wang The skb header should be set to ethernet header before using is_skb_forwardable. Because the ethernet header length has been considered in is_skb_forwardable(including dev->hard_header_len length). To reproduce the issue: 1, add 2 ports on linux bridge br using following commands: $ brctl addbr br $ brctl addif br eth0 $ brctl addif br eth1 2, the MTU of eth0 and eth1 is 1500 3, send a packet(Data 1480, UDP 8, IP 20, Ethernet 14, VLAN 4) from eth0 to eth1 So the expect result is packet larger than 1500 cannot pass through eth0 and eth1. But currently, the packet passes through success, it means eth1's MTU limit doesn't take effect. Fixes: f6367b4660dd ("bridge: use is_skb_forwardable in forward path") Cc: bridge@lists.linux-foundation.org Cc: Nkolay Aleksandrov Cc: Roopa Prabhu Signed-off-by: Yunjian Wang --- v2: -fix commit log and cc the bridge maintainers with fixes tags v3: -add detailed description of packet len and construction --- net/bridge/br_forward.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c index 5372e20..74b688b 100644 --- a/net/bridge/br_forward.c +++ b/net/bridge/br_forward.c @@ -36,10 +36,10 @@ static inline int should_deliver(const struct net_bridge_port *p, int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb) { + skb_push(skb, ETH_HLEN); if (!is_skb_forwardable(skb->dev, skb)) goto drop; - skb_push(skb, ETH_HLEN); br_drop_fake_rtable(skb); if (skb->ip_summed == CHECKSUM_PARTIAL && @@ -97,10 +97,10 @@ static void __br_forward(const struct net_bridge_port *to, net = dev_net(indev); } else { if (unlikely(netpoll_tx_running(to->br->dev))) { + skb_push(skb, ETH_HLEN); if (!is_skb_forwardable(skb->dev, skb)) { kfree_skb(skb); } else { - skb_push(skb, ETH_HLEN); br_netpoll_send_skb(to, skb); } return; -- 1.8.3.1