// SPDX-License-Identifier: GPL-2.0 #include <linux/bpf.h> #include <bpf/bpf_helpers.h> struct { __uint(type, BPF_MAP_TYPE_CGROUP_STORAGE); __type(key, struct bpf_cgroup_storage_key); __type(value, __u64); } cgroup_storage SEC(".maps"); SEC("cgroup_skb/egress") int bpf_prog(struct __sk_buff *skb) { __u64 *counter; counter = bpf_get_local_storage(&cgroup_storage, 0); __sync_fetch_and_add(counter, 1); /* Drop one out of every two packets */ return (*counter & 1); } char _license[] SEC("license") = "GPL";