> On Fri, Jun 27, 2025 at 02:45:28PM +0200, Lorenzo Bianconi wrote:
> > Introduce SW acceleration for IPIP tunnels in the netfilter flowtable
> > infrastructure.
> > IPIP SW acceleration can be tested running the following scenario where
> > the traffic is forwarded between two NICs (eth0 and eth1) and an IPIP
> > tunnel is used to access a remote site (using eth1 as the underlay device):
> >
> > ETH0 -- TUN0 <==> ETH1 -- [IP network] -- TUN1 (192.168.100.2)
> >
> > $ip addr show
> > 6: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP
> > group default qlen 1000
> > link/ether 00:00:22:33:11:55 brd ff:ff:ff:ff:ff:ff
> > inet 192.168.0.2/24 scope global eth0
> > valid_lft forever preferred_lft forever
> > 7: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP
> > group default qlen 1000
> > link/ether 00:11:22:33:11:55 brd ff:ff:ff:ff:ff:ff
> > inet 192.168.1.1/24 scope global eth1
> > valid_lft forever preferred_lft forever
> > 8: tun0@NONE: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1480 qdisc noqueue state
> > UNKNOWN group default qlen 1000
> > link/ipip 192.168.1.1 peer 192.168.1.2
> > inet 192.168.100.1/24 scope global tun0
> > valid_lft forever preferred_lft forever
> >
> > $ip route show
> > default via 192.168.100.2 dev tun0
> > 192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.2
> > 192.168.1.0/24 dev eth1 proto kernel scope link src 192.168.1.1
> > 192.168.100.0/24 dev tun0 proto kernel scope link src 192.168.100.1
> >
> > $nft list ruleset
> > table inet filter {
> > flowtable ft {
> > hook ingress priority filter
> > devices = { eth0, eth1 }
> > }
> >
> > chain forward {
> > type filter hook forward priority filter; policy accept;
> > meta l4proto { tcp, udp } flow add @ft
> > }
> > }
>
> Is there a proof that this accelerates forwarding?I reproduced the scenario described above using veths (something similar to what is done in nft_flowtable.sh) and I got the following results: - flowtable configured as above between the two router interfaces - TCP stream between client and server going via the IPIP tunnel - TCP stream transmitted into the IPIP tunnel: - net-next: ~41Gbps - net-next + IPIP flowtbale support: ~40Gbps - TCP stream received from the IPIP tunnel: - net-next: ~35Gbps - net-next + IPIP flowtbale support: ~49Gbps > > > Signed-off-by: Lorenzo Bianconi <[email protected]> > > --- > > net/ipv4/ipip.c | 21 +++++++++++++++++++++ > > net/netfilter/nf_flow_table_ip.c | 28 ++++++++++++++++++++++++++-- > > 2 files changed, 47 insertions(+), 2 deletions(-) > > [...] > > static bool nf_flow_skb_encap_protocol(struct sk_buff *skb, __be16 proto, > > u32 *offset) > > { > > struct vlan_ethhdr *veth; > > __be16 inner_proto; > > + u16 size; > > > > switch (skb->protocol) { > > + case htons(ETH_P_IP): > > + if (nf_flow_ip4_encap_proto(skb, &size)) > > + *offset += size; > > This is blindly skipping the outer IP header. Do you mean we are supposed to validate the outer IP header performing the sanity checks done in nf_flow_tuple_ip()? Regards, Lorenzo > > > + return true; > > case htons(ETH_P_8021Q): > > if (!pskb_may_pull(skb, skb_mac_offset(skb) + sizeof(*veth))) > > return false; > > @@ -310,6 +328,7 @@ static void nf_flow_encap_pop(struct sk_buff *skb, > > struct flow_offload_tuple_rhash *tuplehash) > > { > > struct vlan_hdr *vlan_hdr; > > + u16 size; > > int i; > > > > for (i = 0; i < tuplehash->tuple.encap_num; i++) { > > @@ -331,6 +350,12 @@ static void nf_flow_encap_pop(struct sk_buff *skb, > > break; > > } > > } > > + > > + if (skb->protocol == htons(ETH_P_IP) && > > + nf_flow_ip4_encap_proto(skb, &size)) { > > + skb_pull(skb, size); > > + skb_reset_network_header(skb); > > + } > > I have a similar patch from 2023, I think I keep somewhere in my trees. > > > } > > > > static unsigned int nf_flow_queue_xmit(struct net *net, struct sk_buff > > *skb, > > @@ -357,8 +382,7 @@ nf_flow_offload_lookup(struct nf_flowtable_ctx *ctx, > > { > > struct flow_offload_tuple tuple = {}; > > > > - if (skb->protocol != htons(ETH_P_IP) && > > - !nf_flow_skb_encap_protocol(skb, htons(ETH_P_IP), &ctx->offset)) > > + if (!nf_flow_skb_encap_protocol(skb, htons(ETH_P_IP), &ctx->offset)) > > return NULL; > > > > if (nf_flow_tuple_ip(ctx, skb, &tuple) < 0) > > > > -- > > 2.50.0 > > >
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