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/* 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.
*/
#define KBUILD_MODNAME "foo"
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/in.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <uapi/linux/bpf.h>
#include <net/ip.h>
#include <bpf/bpf_helpers.h>
#define DEFAULT_PKTGEN_UDP_PORT 9
/* copy of 'struct ethhdr' without __packed */
struct eth_hdr {
unsigned char h_dest[ETH_ALEN];
unsigned char h_source[ETH_ALEN];
unsigned short h_proto;
};
SEC("simple")
int handle_ingress(struct __sk_buff *skb)
{
void *data = (void *)(long)skb->data;
struct eth_hdr *eth = data;
struct iphdr *iph = data + sizeof(*eth);
struct udphdr *udp = data + sizeof(*eth) + sizeof(*iph);
void *data_end = (void *)(long)skb->data_end;
/* single length check */
if (data + sizeof(*eth) + sizeof(*iph) + sizeof(*udp) > data_end)
return 0;
if (eth->h_proto != htons(ETH_P_IP))
return 0;
if (iph->protocol != IPPROTO_UDP || iph->ihl != 5)
return 0;
if (ip_is_fragment(iph))
return 0;
if (udp->dest == htons(DEFAULT_PKTGEN_UDP_PORT))
return TC_ACT_SHOT;
return 0;
}
char _license[] SEC("license") = "GPL";
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