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Message-ID: <160200019693.719143.11586734942253038578.stgit@firesoul>
Date: Tue, 06 Oct 2020 18:03:17 +0200
From: Jesper Dangaard Brouer <brouer@...hat.com>
To: bpf@...r.kernel.org
Cc: Jesper Dangaard Brouer <brouer@...hat.com>, netdev@...r.kernel.org,
Daniel Borkmann <borkmann@...earbox.net>,
Alexei Starovoitov <alexei.starovoitov@...il.com>,
maze@...gle.com, lmb@...udflare.com, shaun@...era.io,
Lorenzo Bianconi <lorenzo@...nel.org>, marek@...udflare.com,
John Fastabend <john.fastabend@...il.com>,
Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH bpf-next V1 6/6] bpf: drop MTU check when doing TC-BPF
redirect to ingress
The use-case for dropping the MTU check when TC-BPF ingress redirecting a
packet, 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/
Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
---
include/linux/netdevice.h | 5 +++--
net/core/dev.c | 2 +-
net/core/filter.c | 12 ++++++++++--
3 files changed, 14 insertions(+), 5 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 28cfa53daf72..58fb7b4869ba 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3866,10 +3866,11 @@ bool is_skb_forwardable(const struct net_device *dev,
const struct sk_buff *skb);
static __always_inline int ____dev_forward_skb(struct net_device *dev,
- struct sk_buff *skb)
+ struct sk_buff *skb,
+ const bool mtu_check)
{
if (skb_orphan_frags(skb, GFP_ATOMIC) ||
- unlikely(!is_skb_forwardable(dev, skb))) {
+ (mtu_check && unlikely(!is_skb_forwardable(dev, skb)))) {
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 33529022b30d..154c342bc061 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2209,7 +2209,7 @@ EXPORT_SYMBOL_GPL(is_skb_forwardable);
int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb)
{
- int ret = ____dev_forward_skb(dev, skb);
+ int ret = ____dev_forward_skb(dev, skb, true);
if (likely(!ret)) {
skb->protocol = eth_type_trans(skb, dev);
diff --git a/net/core/filter.c b/net/core/filter.c
index 49ae3b80027b..69cd6de41f64 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;
}
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;
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