1/* Copyright (c) 2016 PLUMgrid
  2 *
  3 * This program is free software; you can redistribute it and/or
  4 * modify it under the terms of version 2 of the GNU General Public
  5 * License as published by the Free Software Foundation.
  6 */
  7#define KBUILD_MODNAME "foo"
  8#include <uapi/linux/bpf.h>
  9#include <linux/in.h>
 10#include <linux/if_ether.h>
 11#include <linux/if_packet.h>
 12#include <linux/if_vlan.h>
 13#include <linux/ip.h>
 14#include <linux/ipv6.h>
 15#include "bpf_helpers.h"
 16
 17struct bpf_map_def SEC("maps") rxcnt = {
 18	.type = BPF_MAP_TYPE_PERCPU_ARRAY,
 19	.key_size = sizeof(u32),
 20	.value_size = sizeof(long),
 21	.max_entries = 256,
 22};
 23
 24static void swap_src_dst_mac(void *data)
 25{
 26	unsigned short *p = data;
 27	unsigned short dst[3];
 28
 29	dst[0] = p[0];
 30	dst[1] = p[1];
 31	dst[2] = p[2];
 32	p[0] = p[3];
 33	p[1] = p[4];
 34	p[2] = p[5];
 35	p[3] = dst[0];
 36	p[4] = dst[1];
 37	p[5] = dst[2];
 38}
 39
 40static int parse_ipv4(void *data, u64 nh_off, void *data_end)
 41{
 42	struct iphdr *iph = data + nh_off;
 43
 44	if (iph + 1 > data_end)
 45		return 0;
 46	return iph->protocol;
 47}
 48
 49static int parse_ipv6(void *data, u64 nh_off, void *data_end)
 50{
 51	struct ipv6hdr *ip6h = data + nh_off;
 52
 53	if (ip6h + 1 > data_end)
 54		return 0;
 55	return ip6h->nexthdr;
 56}
 57
 58SEC("xdp1")
 59int xdp_prog1(struct xdp_md *ctx)
 60{
 61	void *data_end = (void *)(long)ctx->data_end;
 62	void *data = (void *)(long)ctx->data;
 63	struct ethhdr *eth = data;
 64	int rc = XDP_DROP;
 65	long *value;
 66	u16 h_proto;
 67	u64 nh_off;
 68	u32 ipproto;
 69
 70	nh_off = sizeof(*eth);
 71	if (data + nh_off > data_end)
 72		return rc;
 73
 74	h_proto = eth->h_proto;
 75
 76	if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
 77		struct vlan_hdr *vhdr;
 78
 79		vhdr = data + nh_off;
 80		nh_off += sizeof(struct vlan_hdr);
 81		if (data + nh_off > data_end)
 82			return rc;
 83		h_proto = vhdr->h_vlan_encapsulated_proto;
 84	}
 85	if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
 86		struct vlan_hdr *vhdr;
 87
 88		vhdr = data + nh_off;
 89		nh_off += sizeof(struct vlan_hdr);
 90		if (data + nh_off > data_end)
 91			return rc;
 92		h_proto = vhdr->h_vlan_encapsulated_proto;
 93	}
 94
 95	if (h_proto == htons(ETH_P_IP))
 96		ipproto = parse_ipv4(data, nh_off, data_end);
 97	else if (h_proto == htons(ETH_P_IPV6))
 98		ipproto = parse_ipv6(data, nh_off, data_end);
 99	else
100		ipproto = 0;
101
102	value = bpf_map_lookup_elem(&rxcnt, &ipproto);
103	if (value)
104		*value += 1;
105
106	if (ipproto == IPPROTO_UDP) {
107		swap_src_dst_mac(data);
108		rc = XDP_TX;
109	}
110
111	return rc;
112}
113
114char _license[] SEC("license") = "GPL";