From: Jesper Dangaard Brouer <brouer@redhat.com>
To: bpf@vger.kernel.org
Cc: Jesper Dangaard Brouer <brouer@redhat.com>,
netdev@vger.kernel.org, Daniel Borkmann <borkmann@iogearbox.net>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
maze@google.com, lmb@cloudflare.com, shaun@tigera.io,
Lorenzo Bianconi <lorenzo@kernel.org>,
marek@cloudflare.com, John Fastabend <john.fastabend@gmail.com>,
Jakub Kicinski <kuba@kernel.org>,
eyal.birger@gmail.com
Subject: [PATCH bpf-next V3 5/6] bpf: drop MTU check when doing TC-BPF redirect to ingress
Date: Thu, 08 Oct 2020 16:09:22 +0200 [thread overview]
Message-ID: <160216616276.882446.17894852306425732310.stgit@firesoul> (raw)
In-Reply-To: <160216609656.882446.16642490462568561112.stgit@firesoul>
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/
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.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 b433098896b2..96b455f15872 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 5986156e700e..a8e24092e4f5 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;
next prev parent reply other threads:[~2020-10-08 14:09 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-08 14:08 [PATCH bpf-next V3 0/6] bpf: New approach for BPF MTU handling Jesper Dangaard Brouer
2020-10-08 14:09 ` [PATCH bpf-next V3 1/6] bpf: Remove MTU check in __bpf_skb_max_len Jesper Dangaard Brouer
2020-10-09 16:12 ` Daniel Borkmann
2020-10-09 18:26 ` Maciej Żenczykowski
2020-10-10 10:25 ` Jesper Dangaard Brouer
2020-10-08 14:09 ` [PATCH bpf-next V3 2/6] bpf: bpf_fib_lookup return MTU value as output when looked up Jesper Dangaard Brouer
2020-10-09 4:05 ` David Ahern
2020-10-08 14:09 ` [PATCH bpf-next V3 3/6] bpf: add BPF-helper for MTU checking Jesper Dangaard Brouer
2020-10-09 23:29 ` Maciej Żenczykowski
2020-10-21 11:32 ` Jesper Dangaard Brouer
2020-10-12 15:54 ` Lorenz Bauer
2020-10-08 14:09 ` [PATCH bpf-next V3 4/6] bpf: make it possible to identify BPF redirected SKBs Jesper Dangaard Brouer
2020-10-09 16:47 ` Daniel Borkmann
2020-10-09 18:33 ` Maciej Żenczykowski
2020-10-10 11:09 ` Jesper Dangaard Brouer
2020-10-12 21:04 ` Maciej Żenczykowski
2020-10-08 14:09 ` Jesper Dangaard Brouer [this message]
2020-10-09 23:17 ` [PATCH bpf-next V3 5/6] bpf: drop MTU check when doing TC-BPF redirect to ingress Maciej Żenczykowski
2020-10-08 14:09 ` [PATCH bpf-next V3 6/6] net: inline and splitup is_skb_forwardable Jesper Dangaard Brouer
2020-10-09 16:33 ` [PATCH bpf-next V3 0/6] bpf: New approach for BPF MTU handling Jakub Kicinski
2020-10-09 20:49 ` John Fastabend
2020-10-09 21:07 ` Alexei Starovoitov
2020-10-09 21:57 ` Maciej Żenczykowski
2020-10-09 23:00 ` Jakub Kicinski
2020-10-10 10:44 ` Jesper Dangaard Brouer
2020-10-10 16:32 ` Jakub Kicinski
2020-10-10 23:52 ` John Fastabend
2020-10-11 23:30 ` Jakub Kicinski
2020-10-13 20:40 ` Jesper Dangaard Brouer
2020-10-13 23:07 ` Jakub Kicinski
2020-10-13 23:37 ` Alexei Starovoitov
2020-10-13 23:54 ` Maciej Żenczykowski
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