root/tools/testing/selftests/bpf/progs/test_skb_cgroup_id_kern.c

DEFINITIONS

1. log_nth_level
2. SEC

   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 
  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 int _version SEC("version") = 1;
  46 
  47 char _license[] SEC("license") = "GPL";