Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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
19static 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
25SEC("ldabs")
26int 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}
41char _license[] SEC("license") = "GPL";