1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (c) 2021 Facebook */
3#include <linux/types.h>
4#include <bpf/bpf_helpers.h>
5#include <linux/bpf.h>
6#include <stdint.h>
7
8#define TWFW_MAX_TIERS (64)
9/*
10 * load is successful
11 * #define TWFW_MAX_TIERS (64u)$
12 */
13
14struct twfw_tier_value {
15	unsigned long mask[1];
16};
17
18struct rule {
19	uint8_t seqnum;
20};
21
22struct rules_map {
23	__uint(type, BPF_MAP_TYPE_ARRAY);
24	__type(key, __u32);
25	__type(value, struct rule);
26	__uint(max_entries, 1);
27};
28
29struct tiers_map {
30	__uint(type, BPF_MAP_TYPE_ARRAY);
31	__type(key, __u32);
32	__type(value, struct twfw_tier_value);
33	__uint(max_entries, 1);
34};
35
36struct rules_map rules SEC(".maps");
37struct tiers_map tiers SEC(".maps");
38
39SEC("cgroup_skb/ingress")
40int twfw_verifier(struct __sk_buff* skb)
41{
42	const uint32_t key = 0;
43	const struct twfw_tier_value* tier = bpf_map_lookup_elem(&tiers, &key);
44	if (!tier)
45		return 1;
46
47	struct rule* rule = bpf_map_lookup_elem(&rules, &key);
48	if (!rule)
49		return 1;
50
51	if (rule && rule->seqnum < TWFW_MAX_TIERS) {
52		/* rule->seqnum / 64 should always be 0 */
53		unsigned long mask = tier->mask[rule->seqnum / 64];
54		if (mask)
55			return 0;
56	}
57	return 1;
58}
59