From patchwork Tue Feb 9 13:38:29 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Dangaard Brouer X-Patchwork-Id: 12078171 X-Patchwork-Delegate: bpf@iogearbox.net 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=-16.3 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=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 B10E3C433E6 for ; Tue, 9 Feb 2021 13:41:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7026364ECB for ; Tue, 9 Feb 2021 13:41:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231674AbhBINll (ORCPT ); Tue, 9 Feb 2021 08:41:41 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:44307 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230357AbhBINkI (ORCPT ); Tue, 9 Feb 2021 08:40:08 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612877920; 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=o44qZTf3caDj80NiJSuYB7msdHW2H7XuWQWXTjF7DKk=; b=FGwb1S0tPahdHFkppEK5Zwlc+vghlj5W+5NsdBpeIRnuFVFIF7MvaKHLsn0A2oy2r5OgnQ Lk0t9Ir35qKLCIXZ9Imrb/+HUuhbzdqosiXQC2zY/gWyYWyUP62aFRyXG4JC13BGkhKtjd WbU6m2yXyE0jop3qxGLi1pGLV7nbEvg= 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-494-AGVPuBZDNYmAYTuI8cV7Qw-1; Tue, 09 Feb 2021 08:38:37 -0500 X-MC-Unique: AGVPuBZDNYmAYTuI8cV7Qw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 41F0D83DCC7; Tue, 9 Feb 2021 13:38:35 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id C7DC45D9C0; Tue, 9 Feb 2021 13:38:30 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id C4D1E30736C73; Tue, 9 Feb 2021 14:38:29 +0100 (CET) Subject: [PATCH bpf-next V16 5/7] bpf: drop MTU check when doing TC-BPF redirect to ingress From: Jesper Dangaard Brouer To: bpf@vger.kernel.org Cc: Jesper Dangaard Brouer , netdev@vger.kernel.org, Daniel Borkmann , Alexei Starovoitov , maze@google.com, lmb@cloudflare.com, shaun@tigera.io, Lorenzo Bianconi , marek@cloudflare.com, John Fastabend , Jakub Kicinski , eyal.birger@gmail.com, colrack@gmail.com Date: Tue, 09 Feb 2021 14:38:29 +0100 Message-ID: <161287790971.790810.11785274340154740591.stgit@firesoul> In-Reply-To: <161287779408.790810.15631860742170694244.stgit@firesoul> References: <161287779408.790810.15631860742170694244.stgit@firesoul> User-Agent: StGit/0.19 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net 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/ V15: - missing static for function declaration 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 Acked-by: John Fastabend --- include/linux/netdevice.h | 32 ++++++++++++++++++++++++++++++-- net/core/dev.c | 32 ++++++++++++++------------------ net/core/filter.c | 6 +++--- 3 files changed, 47 insertions(+), 23 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index ef517254367d..b9bcbfde7849 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -3931,14 +3931,42 @@ int xdp_umem_query(struct net_device *dev, u16 queue_id); int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb); int dev_forward_skb(struct net_device *dev, struct sk_buff *skb); +int dev_forward_skb_nomtu(struct net_device *dev, struct sk_buff *skb); bool is_skb_forwardable(const struct net_device *dev, const struct sk_buff *skb); +static __always_inline bool __is_skb_forwardable(const struct net_device *dev, + const struct sk_buff *skb, + const bool check_mtu) +{ + const u32 vlan_hdr_len = 4; /* VLAN_HLEN */ + unsigned int len; + + if (!(dev->flags & IFF_UP)) + return false; + + if (!check_mtu) + return true; + + len = dev->mtu + dev->hard_header_len + vlan_hdr_len; + if (skb->len <= len) + return true; + + /* if TSO is enabled, we don't care about the length as the packet + * could be forwarded without being segmented before + */ + if (skb_is_gso(skb)) + return true; + + return false; +} + static __always_inline int ____dev_forward_skb(struct net_device *dev, - struct sk_buff *skb) + struct sk_buff *skb, + const bool check_mtu) { if (skb_orphan_frags(skb, GFP_ATOMIC) || - unlikely(!is_skb_forwardable(dev, skb))) { + unlikely(!__is_skb_forwardable(dev, skb, check_mtu))) { atomic_long_inc(&dev->rx_dropped); kfree_skb(skb); return NET_RX_DROP; diff --git a/net/core/dev.c b/net/core/dev.c index 07a0347c33fb..8c820fe0eff3 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2194,28 +2194,14 @@ static inline void net_timestamp_set(struct sk_buff *skb) bool is_skb_forwardable(const struct net_device *dev, const struct sk_buff *skb) { - unsigned int len; - - if (!(dev->flags & IFF_UP)) - return false; - - len = dev->mtu + dev->hard_header_len + VLAN_HLEN; - if (skb->len <= len) - return true; - - /* if TSO is enabled, we don't care about the length as the packet - * could be forwarded without being segmented before - */ - if (skb_is_gso(skb)) - return true; - - return false; + return __is_skb_forwardable(dev, skb, true); } EXPORT_SYMBOL_GPL(is_skb_forwardable); -int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb) +static int __dev_forward_skb2(struct net_device *dev, struct sk_buff *skb, + bool check_mtu) { - int ret = ____dev_forward_skb(dev, skb); + int ret = ____dev_forward_skb(dev, skb, check_mtu); if (likely(!ret)) { skb->protocol = eth_type_trans(skb, dev); @@ -2224,6 +2210,11 @@ int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb) return ret; } + +int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb) +{ + return __dev_forward_skb2(dev, skb, true); +} EXPORT_SYMBOL_GPL(__dev_forward_skb); /** @@ -2250,6 +2241,11 @@ int dev_forward_skb(struct net_device *dev, struct sk_buff *skb) } EXPORT_SYMBOL_GPL(dev_forward_skb); +int dev_forward_skb_nomtu(struct net_device *dev, struct sk_buff *skb) +{ + return __dev_forward_skb2(dev, skb, false) ?: netif_rx_internal(skb); +} + static inline int deliver_skb(struct sk_buff *skb, struct packet_type *pt_prev, struct net_device *orig_dev) diff --git a/net/core/filter.c b/net/core/filter.c index 18beaf82b8b8..0c1819b37fdf 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2083,13 +2083,13 @@ 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); + return dev_forward_skb_nomtu(dev, skb); } static inline int __bpf_rx_skb_no_mac(struct net_device *dev, struct sk_buff *skb) { - int ret = ____dev_forward_skb(dev, skb); + int ret = ____dev_forward_skb(dev, skb, false); if (likely(!ret)) { skb->dev = dev; @@ -2480,7 +2480,7 @@ int skb_do_redirect(struct sk_buff *skb) goto out_drop; dev = ops->ndo_get_peer_dev(dev); if (unlikely(!dev || - !is_skb_forwardable(dev, skb) || + !(dev->flags & IFF_UP) || net_eq(net, dev_net(dev)))) goto out_drop; skb->dev = dev;