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1// SPDX-License-Identifier: GPL-2.02// Copyright (c) 2018 Facebook3 4#include <vmlinux.h>5#include <bpf/bpf_helpers.h>6#include <bpf/bpf_core_read.h>7#include "bpf_tracing_net.h"8#define NUM_CGROUP_LEVELS 49 10__u64 cgroup_ids[NUM_CGROUP_LEVELS];11__u16 dport;12 13static __always_inline void log_nth_level(struct __sk_buff *skb, __u32 level)14{15 /* [1] &level passed to external function that may change it, it's16 * incompatible with loop unroll.17 */18 cgroup_ids[level] = bpf_skb_ancestor_cgroup_id(skb, level);19}20 21SEC("tc")22int log_cgroup_id(struct __sk_buff *skb)23{24 struct sock *sk = (void *)skb->sk;25 26 if (!sk)27 return TC_ACT_OK;28 29 sk = bpf_core_cast(sk, struct sock);30 if (sk->sk_protocol == IPPROTO_UDP && sk->sk_dport == dport) {31 log_nth_level(skb, 0);32 log_nth_level(skb, 1);33 log_nth_level(skb, 2);34 log_nth_level(skb, 3);35 }36 37 return TC_ACT_OK;38}39 40char _license[] SEC("license") = "GPL";41