/* 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";