tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
13struct 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
20static __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
31SEC("cgroup_id_logger")
32int 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
45int _version SEC("version") = 1;
46
47char _license[] SEC("license") = "GPL";