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_helpers.h"
10
11 #define NUM_CGROUP_LEVELS 4
12
13 struct bpf_map_def SEC("maps") cgroup_ids = {
14 .type = BPF_MAP_TYPE_ARRAY,
15 .key_size = sizeof(__u32),
16 .value_size = sizeof(__u64),
17 .max_entries = NUM_CGROUP_LEVELS,
18 };
19
log_nth_level(struct __sk_buff * skb,__u32 level)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")
log_cgroup_id(struct __sk_buff * skb)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 int _version SEC("version") = 1;
46
47 char _license[] SEC("license") = "GPL";
48