1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (c) 2018 Facebook 3 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 4 9 10 __u64 cgroup_ids[NUM_CGROUP_LEVELS]; 11 __u16 dport; 12 13 static __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's 16 * incompatible with loop unroll. 17 */ 18 cgroup_ids[level] = bpf_skb_ancestor_cgroup_id(skb, level); 19 } 20 21 SEC("tc") 22 int 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 40 char _license[] SEC("license") = "GPL"; 41