/* Copyright (c) 2016 Facebook
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*
* This program shows how to use bpf_xdp_adjust_head() by
* encapsulating the incoming packet in an IPv4/v6 header
* and then XDP_TX it out.
*/
#define KBUILD_MODNAME "foo"
#include <uapi/linux/bpf.h>
#include <linux/in.h>
#include <linux/if_ether.h>
#include <linux/if_packet.h>
#include <linux/if_vlan.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include "bpf_helpers.h"
#include "xdp_tx_iptunnel_common.h"
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
__type(key, __u32);
__type(value, __u64);
__uint(max_entries, 256);
} rxcnt SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__type(key, struct vip);
__type(value, struct iptnl_info);
__uint(max_entries, MAX_IPTNL_ENTRIES);
} vip2tnl SEC(".maps");
static __always_inline void count_tx(u32 protocol)
{
u64 *rxcnt_count;
rxcnt_count = bpf_map_lookup_elem(&rxcnt, &protocol);
if (rxcnt_count)
*rxcnt_count += 1;
}
static __always_inline int get_dport(void *trans_data, void *data_end,
u8 protocol)
{
struct tcphdr *th;
struct udphdr *uh;
switch (protocol) {
case IPPROTO_TCP:
th = (struct tcphdr *)trans_data;
if (th + 1 > data_end)
return -1;
return th->dest;
case IPPROTO_UDP:
uh = (struct udphdr *)trans_data;
if (uh + 1 > data_end)
return -1;
return uh->dest;
default:
return 0;
}
}
static __always_inline void set_ethhdr(struct ethhdr *new_eth,
const struct ethhdr *old_eth,
const struct iptnl_info *tnl,
__be16 h_proto)
{
memcpy(new_eth->h_source, old_eth->h_dest, sizeof(new_eth->h_source));
memcpy(new_eth->h_dest, tnl->dmac, sizeof(new_eth->h_dest));
new_eth->h_proto = h_proto;
}
static __always_inline int handle_ipv4(struct xdp_md *xdp)
{
void *data_end = (void *)(long)xdp->data_end;
void *data = (void *)(long)xdp->data;
struct iptnl_info *tnl;
struct ethhdr *new_eth;
struct ethhdr *old_eth;
struct iphdr *iph = data + sizeof(struct ethhdr);
u16 *next_iph_u16;
u16 payload_len;
struct vip vip = {};
int dport;
u32 csum = 0;
int i;
if (iph + 1 > data_end)
return XDP_DROP;
dport = get_dport(iph + 1, data_end, iph->protocol);
if (dport == -1)
return XDP_DROP;
vip.protocol = iph->protocol;
vip.family = AF_INET;
vip.daddr.v4 = iph->daddr;
vip.dport = dport;
payload_len = ntohs(iph->tot_len);
tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
/* It only does v4-in-v4 */
if (!tnl || tnl->family != AF_INET)
return XDP_PASS;
/* The vip key is found. Add an IP header and send it out */
if (bpf_xdp_adjust_head(xdp, 0 - (int)sizeof(struct iphdr)))
return XDP_DROP;
data = (void *)(long)xdp->data;
data_end = (void *)(long)xdp->data_end;
new_eth = data;
iph = data + sizeof(*new_eth);
old_eth = data + sizeof(*iph);
if (new_eth + 1 > data_end ||
old_eth + 1 > data_end ||
iph + 1 > data_end)
return XDP_DROP;
set_ethhdr(new_eth, old_eth, tnl, htons(ETH_P_IP));
iph->version = 4;
iph->ihl = sizeof(*iph) >> 2;
iph->frag_off = 0;
iph->protocol = IPPROTO_IPIP;
iph->check = 0;
iph->tos = 0;
iph->tot_len = htons(payload_len + sizeof(*iph));
iph->daddr = tnl->daddr.v4;
iph->saddr = tnl->saddr.v4;
iph->ttl = 8;
next_iph_u16 = (u16 *)iph;
#pragma clang loop unroll(full)
for (i = 0; i < sizeof(*iph) >> 1; i++)
csum += *next_iph_u16++;
iph->check = ~((csum & 0xffff) + (csum >> 16));
count_tx(vip.protocol);
return XDP_TX;
}
static __always_inline int handle_ipv6(struct xdp_md *xdp)
{
void *data_end = (void *)(long)xdp->data_end;
void *data = (void *)(long)xdp->data;
struct iptnl_info *tnl;
struct ethhdr *new_eth;
struct ethhdr *old_eth;
struct ipv6hdr *ip6h = data + sizeof(struct ethhdr);
__u16 payload_len;
struct vip vip = {};
int dport;
if (ip6h + 1 > data_end)
return XDP_DROP;
dport = get_dport(ip6h + 1, data_end, ip6h->nexthdr);
if (dport == -1)
return XDP_DROP;
vip.protocol = ip6h->nexthdr;
vip.family = AF_INET6;
memcpy(vip.daddr.v6, ip6h->daddr.s6_addr32, sizeof(vip.daddr));
vip.dport = dport;
payload_len = ip6h->payload_len;
tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
/* It only does v6-in-v6 */
if (!tnl || tnl->family != AF_INET6)
return XDP_PASS;
/* The vip key is found. Add an IP header and send it out */
if (bpf_xdp_adjust_head(xdp, 0 - (int)sizeof(struct ipv6hdr)))
return XDP_DROP;
data = (void *)(long)xdp->data;
data_end = (void *)(long)xdp->data_end;
new_eth = data;
ip6h = data + sizeof(*new_eth);
old_eth = data + sizeof(*ip6h);
if (new_eth + 1 > data_end ||
old_eth + 1 > data_end ||
ip6h + 1 > data_end)
return XDP_DROP;
set_ethhdr(new_eth, old_eth, tnl, htons(ETH_P_IPV6));
ip6h->version = 6;
ip6h->priority = 0;
memset(ip6h->flow_lbl, 0, sizeof(ip6h->flow_lbl));
ip6h->payload_len = htons(ntohs(payload_len) + sizeof(*ip6h));
ip6h->nexthdr = IPPROTO_IPV6;
ip6h->hop_limit = 8;
memcpy(ip6h->saddr.s6_addr32, tnl->saddr.v6, sizeof(tnl->saddr.v6));
memcpy(ip6h->daddr.s6_addr32, tnl->daddr.v6, sizeof(tnl->daddr.v6));
count_tx(vip.protocol);
return XDP_TX;
}
SEC("xdp_tx_iptunnel")
int _xdp_tx_iptunnel(struct xdp_md *xdp)
{
void *data_end = (void *)(long)xdp->data_end;
void *data = (void *)(long)xdp->data;
struct ethhdr *eth = data;
__u16 h_proto;
if (eth + 1 > data_end)
return XDP_DROP;
h_proto = eth->h_proto;
if (h_proto == htons(ETH_P_IP))
return handle_ipv4(xdp);
else if (h_proto == htons(ETH_P_IPV6))
return handle_ipv6(xdp);
else
return XDP_PASS;
}
char _license[] SEC("license") = "GPL";
