/* 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_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";