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1/* Copyright (c) 2016 Facebook2 *3 * This program is free software; you can redistribute it and/or4 * modify it under the terms of version 2 of the GNU General Public5 * License as published by the Free Software Foundation.6 */7#define KBUILD_MODNAME "foo"8#include <linux/ip.h>9#include <linux/ipv6.h>10#include <linux/in.h>11#include <linux/tcp.h>12#include <linux/udp.h>13#include <uapi/linux/bpf.h>14#include <net/ip.h>15#include <bpf/bpf_helpers.h>16 17#define DEFAULT_PKTGEN_UDP_PORT 918 19/* copy of 'struct ethhdr' without __packed */20struct eth_hdr {21 unsigned char h_dest[ETH_ALEN];22 unsigned char h_source[ETH_ALEN];23 unsigned short h_proto;24};25 26SEC("simple")27int handle_ingress(struct __sk_buff *skb)28{29 void *data = (void *)(long)skb->data;30 struct eth_hdr *eth = data;31 struct iphdr *iph = data + sizeof(*eth);32 struct udphdr *udp = data + sizeof(*eth) + sizeof(*iph);33 void *data_end = (void *)(long)skb->data_end;34 35 /* single length check */36 if (data + sizeof(*eth) + sizeof(*iph) + sizeof(*udp) > data_end)37 return 0;38 39 if (eth->h_proto != htons(ETH_P_IP))40 return 0;41 if (iph->protocol != IPPROTO_UDP || iph->ihl != 5)42 return 0;43 if (ip_is_fragment(iph))44 return 0;45 if (udp->dest == htons(DEFAULT_PKTGEN_UDP_PORT))46 return TC_ACT_SHOT;47 return 0;48}49char _license[] SEC("license") = "GPL";50