| Alexei Starovoitov | 65d472f | 2016-05-05 19:49:14 -0700 | [diff] [blame] | 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"; |