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65d472fb AS |
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"; |