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=-16.0 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 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 9A612C433DB for ; Thu, 14 Jan 2021 16:16:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6FC6C23B2A for ; Thu, 14 Jan 2021 16:16:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725918AbhANQQL (ORCPT ); Thu, 14 Jan 2021 11:16:11 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:28123 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726108AbhANQQL (ORCPT ); Thu, 14 Jan 2021 11:16:11 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1610640884; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Qee0DcZxR0fVVmjSULZKOay9OvqVZKocCovyVyOW/28=; b=Kujf5xEk8Wk1Raqtgwh7efGZt85bGhfvtGHFRlOivXhoFPrkYvqUaabXDwR2dD085O5kCb +NTOK/5DZT7r/t73F01LeGXWyaVEGQcgOzlfyFsKDCTF+1ShdqYNTMKNmDu6c+H8eqnlPo jbRjN6MQdVqyTcyTtMP+WS7v/RHhgow= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-503-8_NQ3No7MeuV4G2PYUeSRw-1; Thu, 14 Jan 2021 11:14:39 -0500 X-MC-Unique: 8_NQ3No7MeuV4G2PYUeSRw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 87AA1100C664; Thu, 14 Jan 2021 16:14:37 +0000 (UTC) Received: from carbon (unknown [10.36.110.51]) by smtp.corp.redhat.com (Postfix) with ESMTP id 61BB65C1A3; Thu, 14 Jan 2021 16:14:31 +0000 (UTC) Date: Thu, 14 Jan 2021 17:14:29 +0100 From: Jesper Dangaard Brouer To: John Fastabend Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, Daniel Borkmann , Alexei Starovoitov , maze@google.com, lmb@cloudflare.com, shaun@tigera.io, Lorenzo Bianconi , marek@cloudflare.com, Jakub Kicinski , eyal.birger@gmail.com, colrack@gmail.com, brouer@redhat.com Subject: Re: [PATCH bpf-next V11 5/7] bpf: drop MTU check when doing TC-BPF redirect to ingress Message-ID: <20210114171429.1402ca3d@carbon> In-Reply-To: <600008e5e2e80_1eeef20852@john-XPS-13-9370.notmuch> References: <161047346644.4003084.2653117664787086168.stgit@firesoul> <161047352593.4003084.6778762780747210369.stgit@firesoul> <600008e5e2e80_1eeef20852@john-XPS-13-9370.notmuch> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Thu, 14 Jan 2021 01:03:33 -0800 John Fastabend wrote: > Jesper Dangaard Brouer wrote: > > The use-case for dropping the MTU check when TC-BPF does redirect to > > ingress, is described by Eyal Birger in email[0]. The summary is the > > ability to increase packet size (e.g. with IPv6 headers for NAT64) and > > ingress redirect packet and let normal netstack fragment packet as needed. > > > > [0] https://lore.kernel.org/netdev/CAHsH6Gug-hsLGHQ6N0wtixdOa85LDZ3HNRHVd0opR=19Qo4W4Q@mail.gmail.com/ > > > > V9: > > - Make net_device "up" (IFF_UP) check explicit in skb_do_redirect > > > > V4: > > - Keep net_device "up" (IFF_UP) check. > > - Adjustment to handle bpf_redirect_peer() helper > > > > Signed-off-by: Jesper Dangaard Brouer > > --- > > include/linux/netdevice.h | 31 +++++++++++++++++++++++++++++-- > > net/core/dev.c | 19 ++----------------- > > net/core/filter.c | 14 +++++++++++--- > > 3 files changed, 42 insertions(+), 22 deletions(-) > > > > [...] > > > diff --git a/net/core/filter.c b/net/core/filter.c > > index 3f2e593244ca..1908800b671c 100644 > > --- a/net/core/filter.c > > +++ b/net/core/filter.c > > @@ -2083,13 +2083,21 @@ static const struct bpf_func_proto bpf_csum_level_proto = { > > > > static inline int __bpf_rx_skb(struct net_device *dev, struct sk_buff *skb) > > { > > - return dev_forward_skb(dev, skb); > > > + int ret = ____dev_forward_skb(dev, skb, false); > > + > > + if (likely(!ret)) { > > + skb->protocol = eth_type_trans(skb, dev); > > + skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN); > > + ret = netif_rx(skb); > > + } > > + > > + return ret; > > How about putting above block into a dev.c routine call it > > dev_forward_skb_nomtu(...) > > or something like that. Then we keep this code next to its pair > with mtu check, dev_forward_skb(). > > dev_forward_skb() also uses netif_rx_internal() looks like maybe we should > just do the same here? I love the idea. I'm coding it up and it looks much nicer. And yes we obviously can use netif_rx_internal() once the code in core/dev.c -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer