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49 lines
1.3 KiB
49 lines
1.3 KiB
/* Copyright (c) 2016 Facebook |
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* |
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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of version 2 of the GNU General Public |
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* License as published by the Free Software Foundation. |
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*/ |
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#define KBUILD_MODNAME "foo" |
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#include <linux/ip.h> |
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#include <linux/ipv6.h> |
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#include <linux/in.h> |
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#include <linux/tcp.h> |
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#include <linux/udp.h> |
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#include <uapi/linux/bpf.h> |
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#include <net/ip.h> |
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#include <bpf/bpf_helpers.h> |
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#define DEFAULT_PKTGEN_UDP_PORT 9 |
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/* copy of 'struct ethhdr' without __packed */ |
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struct eth_hdr { |
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unsigned char h_dest[ETH_ALEN]; |
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unsigned char h_source[ETH_ALEN]; |
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unsigned short h_proto; |
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}; |
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SEC("simple") |
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int handle_ingress(struct __sk_buff *skb) |
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{ |
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void *data = (void *)(long)skb->data; |
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struct eth_hdr *eth = data; |
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struct iphdr *iph = data + sizeof(*eth); |
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struct udphdr *udp = data + sizeof(*eth) + sizeof(*iph); |
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void *data_end = (void *)(long)skb->data_end; |
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/* single length check */ |
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if (data + sizeof(*eth) + sizeof(*iph) + sizeof(*udp) > data_end) |
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return 0; |
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if (eth->h_proto != htons(ETH_P_IP)) |
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return 0; |
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if (iph->protocol != IPPROTO_UDP || iph->ihl != 5) |
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return 0; |
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if (ip_is_fragment(iph)) |
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return 0; |
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if (udp->dest == htons(DEFAULT_PKTGEN_UDP_PORT)) |
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return TC_ACT_SHOT; |
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return 0; |
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} |
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char _license[] SEC("license") = "GPL";
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