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37 lines
969 B
C
37 lines
969 B
C
// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
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/* Copyright (c) 2022 Hengqi Chen */
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#include <vmlinux.h>
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#include <bpf/bpf_endian.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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#define TC_ACT_OK 0
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#define ETH_P_IP 0x0800 /* Internet Protocol packet */
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/// @tchook {"ifindex":1, "attach_point":"BPF_TC_INGRESS"}
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/// @tcopts {"handle":1, "priority":1}
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SEC("tc")
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int tc_ingress(struct __sk_buff *ctx)
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{
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void *data_end = (void *)(__u64)ctx->data_end;
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void *data = (void *)(__u64)ctx->data;
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struct ethhdr *l2;
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struct iphdr *l3;
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if (ctx->protocol != bpf_htons(ETH_P_IP))
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return TC_ACT_OK;
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l2 = data;
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if ((void *)(l2 + 1) > data_end)
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return TC_ACT_OK;
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l3 = (struct iphdr *)(l2 + 1);
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if ((void *)(l3 + 1) > data_end)
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return TC_ACT_OK;
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bpf_printk("Got IP packet: tot_len: %d, ttl: %d", bpf_ntohs(l3->tot_len), l3->ttl);
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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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