| /* 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 "bpf_helpers.h" |
| |
| #define DEFAULT_PKTGEN_UDP_PORT 9 |
| #define IP_MF 0x2000 |
| #define IP_OFFSET 0x1FFF |
| |
| static inline int ip_is_fragment(struct __sk_buff *ctx, __u64 nhoff) |
| { |
| return load_half(ctx, nhoff + offsetof(struct iphdr, frag_off)) |
| & (IP_MF | IP_OFFSET); |
| } |
| |
| SEC("ldabs") |
| int handle_ingress(struct __sk_buff *skb) |
| { |
| __u64 troff = ETH_HLEN + sizeof(struct iphdr); |
| |
| if (load_half(skb, offsetof(struct ethhdr, h_proto)) != ETH_P_IP) |
| return 0; |
| if (load_byte(skb, ETH_HLEN + offsetof(struct iphdr, protocol)) != IPPROTO_UDP || |
| load_byte(skb, ETH_HLEN) != 0x45) |
| return 0; |
| if (ip_is_fragment(skb, ETH_HLEN)) |
| return 0; |
| if (load_half(skb, troff + offsetof(struct udphdr, dest)) == DEFAULT_PKTGEN_UDP_PORT) |
| return TC_ACT_SHOT; |
| return 0; |
| } |
| char _license[] SEC("license") = "GPL"; |