50 lines
1.3 KiB
C
50 lines
1.3 KiB
C
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/* 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_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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