| 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 "bpf_helpers.h" |
| 14 | |
| 15 | #define DEFAULT_PKTGEN_UDP_PORT 9 |
| 16 | #define IP_MF 0x2000 |
| 17 | #define IP_OFFSET 0x1FFF |
| 18 | |
| 19 | static inline int ip_is_fragment(struct __sk_buff *ctx, __u64 nhoff) |
| 20 | { |
| 21 | return load_half(ctx, nhoff + offsetof(struct iphdr, frag_off)) |
| 22 | & (IP_MF | IP_OFFSET); |
| 23 | } |
| 24 | |
| 25 | SEC("ldabs") |
| 26 | int handle_ingress(struct __sk_buff *skb) |
| 27 | { |
| 28 | __u64 troff = ETH_HLEN + sizeof(struct iphdr); |
| 29 | |
| 30 | if (load_half(skb, offsetof(struct ethhdr, h_proto)) != ETH_P_IP) |
| 31 | return 0; |
| 32 | if (load_byte(skb, ETH_HLEN + offsetof(struct iphdr, protocol)) != IPPROTO_UDP || |
| 33 | load_byte(skb, ETH_HLEN) != 0x45) |
| 34 | return 0; |
| 35 | if (ip_is_fragment(skb, ETH_HLEN)) |
| 36 | return 0; |
| 37 | if (load_half(skb, troff + offsetof(struct udphdr, dest)) == DEFAULT_PKTGEN_UDP_PORT) |
| 38 | return TC_ACT_SHOT; |
| 39 | return 0; |
| 40 | } |
| 41 | char _license[] SEC("license") = "GPL"; |