1 /* Copyright (c) 2016 Facebook 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 #include <linux/ip.h> 8 #include <linux/ipv6.h> 9 #include <linux/in.h> 10 #include <linux/tcp.h> 11 #include <linux/udp.h> 12 #include <uapi/linux/bpf.h> 13 #include <net/ip.h> 14 #include "bpf_helpers.h" 15 16 #define DEFAULT_PKTGEN_UDP_PORT 9 17 18 /* copy of 'struct ethhdr' without __packed */ 19 struct eth_hdr { 20 unsigned char h_dest[ETH_ALEN]; 21 unsigned char h_source[ETH_ALEN]; 22 unsigned short h_proto; 23 }; 24 25 SEC("simple") 26 int handle_ingress(struct __sk_buff *skb) 27 { 28 void *data = (void *)(long)skb->data; 29 struct eth_hdr *eth = data; 30 struct iphdr *iph = data + sizeof(*eth); 31 struct udphdr *udp = data + sizeof(*eth) + sizeof(*iph); 32 void *data_end = (void *)(long)skb->data_end; 33 34 /* single length check */ 35 if (data + sizeof(*eth) + sizeof(*iph) + sizeof(*udp) > data_end) 36 return 0; 37 38 if (eth->h_proto != htons(ETH_P_IP)) 39 return 0; 40 if (iph->protocol != IPPROTO_UDP || iph->ihl != 5) 41 return 0; 42 if (ip_is_fragment(iph)) 43 return 0; 44 if (udp->dest == htons(DEFAULT_PKTGEN_UDP_PORT)) 45 return TC_ACT_SHOT; 46 return 0; 47 } 48 char _license[] SEC("license") = "GPL"; 49