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/* Copyright (c) 2016 PLUMgrid
*
* 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.
*/
#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/bpf_helpers.h>
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
__type(key, u32);
__type(value, long);
__uint(max_entries, 256);
} rxcnt SEC(".maps");
static void swap_src_dst_mac(void *data)
{
unsigned short *p = data;
unsigned short dst[3];
dst[0] = p[0];
dst[1] = p[1];
dst[2] = p[2];
p[0] = p[3];
p[1] = p[4];
p[2] = p[5];
p[3] = dst[0];
p[4] = dst[1];
p[5] = dst[2];
}
static int parse_ipv4(void *data, u64 nh_off, void *data_end)
{
struct iphdr *iph = data + nh_off;
if (iph + 1 > data_end)
return 0;
return iph->protocol;
}
static int parse_ipv6(void *data, u64 nh_off, void *data_end)
{
struct ipv6hdr *ip6h = data + nh_off;
if (ip6h + 1 > data_end)
return 0;
return ip6h->nexthdr;
}
#define XDPBUFSIZE 60
SEC("xdp.frags")
int xdp_prog1(struct xdp_md *ctx)
{
__u8 pkt[XDPBUFSIZE] = {};
void *data_end = &pkt[XDPBUFSIZE-1];
void *data = pkt;
struct ethhdr *eth = data;
int rc = XDP_DROP;
long *value;
u16 h_proto;
u64 nh_off;
u32 ipproto;
if (bpf_xdp_load_bytes(ctx, 0, pkt, sizeof(pkt)))
return rc;
nh_off = sizeof(*eth);
if (data + nh_off > data_end)
return rc;
h_proto = eth->h_proto;
/* Handle VLAN tagged packet */
if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
struct vlan_hdr *vhdr;
vhdr = data + nh_off;
nh_off += sizeof(struct vlan_hdr);
if (data + nh_off > data_end)
return rc;
h_proto = vhdr->h_vlan_encapsulated_proto;
}
/* Handle double VLAN tagged packet */
if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
struct vlan_hdr *vhdr;
vhdr = data + nh_off;
nh_off += sizeof(struct vlan_hdr);
if (data + nh_off > data_end)
return rc;
h_proto = vhdr->h_vlan_encapsulated_proto;
}
if (h_proto == htons(ETH_P_IP))
ipproto = parse_ipv4(data, nh_off, data_end);
else if (h_proto == htons(ETH_P_IPV6))
ipproto = parse_ipv6(data, nh_off, data_end);
else
ipproto = 0;
value = bpf_map_lookup_elem(&rxcnt, &ipproto);
if (value)
*value += 1;
if (ipproto == IPPROTO_UDP) {
swap_src_dst_mac(data);
if (bpf_xdp_store_bytes(ctx, 0, pkt, sizeof(pkt)))
return rc;
rc = XDP_TX;
}
return rc;
}
char _license[] SEC("license") = "GPL";
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