1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (c) 2018 Facebook 3 4 #include <linux/bpf.h> 5 #include <linux/pkt_cls.h> 6 7 #include <string.h> 8 9 #include <bpf/bpf_helpers.h> 10 11 #define NUM_CGROUP_LEVELS 4 12 13 struct { 14 __uint(type, BPF_MAP_TYPE_ARRAY); 15 __type(key, __u32); 16 __type(value, __u64); 17 __uint(max_entries, NUM_CGROUP_LEVELS); 18 } cgroup_ids SEC(".maps"); 19 20 static __always_inline void log_nth_level(struct __sk_buff *skb, __u32 level) 21 { 22 __u64 id; 23 24 /* [1] &level passed to external function that may change it, it's 25 * incompatible with loop unroll. 26 */ 27 id = bpf_skb_ancestor_cgroup_id(skb, level); 28 bpf_map_update_elem(&cgroup_ids, &level, &id, 0); 29 } 30 31 SEC("cgroup_id_logger") 32 int log_cgroup_id(struct __sk_buff *skb) 33 { 34 /* Loop unroll can't be used here due to [1]. Unrolling manually. 35 * Number of calls should be in sync with NUM_CGROUP_LEVELS. 36 */ 37 log_nth_level(skb, 0); 38 log_nth_level(skb, 1); 39 log_nth_level(skb, 2); 40 log_nth_level(skb, 3); 41 42 return TC_ACT_OK; 43 } 44 45 char _license[] SEC("license") = "GPL"; 46