58 lines
1.1 KiB
C
58 lines
1.1 KiB
C
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/* SPDX-License-Identifier: GPL-2.0 */
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// Copyright (c) 2018 Politecnico di Torino
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#include <stddef.h>
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#include <string.h>
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#include <linux/bpf.h>
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#include <linux/if_ether.h>
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#include <linux/ip.h>
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#include <linux/pkt_cls.h>
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#include <bpf/bpf_helpers.h>
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struct {
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__uint(type, MAP_TYPE);
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__uint(max_entries, 32);
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__uint(map_flags, 0);
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__uint(key_size, 0);
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__uint(value_size, sizeof(__u32));
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} map_in SEC(".maps");
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struct {
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__uint(type, MAP_TYPE);
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__uint(max_entries, 32);
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__uint(map_flags, 0);
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__uint(key_size, 0);
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__uint(value_size, sizeof(__u32));
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} map_out SEC(".maps");
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SEC("tc")
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int _test(struct __sk_buff *skb)
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{
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void *data_end = (void *)(long)skb->data_end;
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void *data = (void *)(long)skb->data;
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struct ethhdr *eth = (struct ethhdr *)(data);
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__u32 value;
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int err;
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if (eth + 1 > data_end)
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return TC_ACT_SHOT;
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struct iphdr *iph = (struct iphdr *)(eth + 1);
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if (iph + 1 > data_end)
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return TC_ACT_SHOT;
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err = bpf_map_pop_elem(&map_in, &value);
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if (err)
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return TC_ACT_SHOT;
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iph->daddr = value;
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err = bpf_map_push_elem(&map_out, &iph->saddr, 0);
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if (err)
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return TC_ACT_SHOT;
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return TC_ACT_OK;
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}
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char _license[] SEC("license") = "GPL";
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