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
14 struct twfw_tier_value {
15 unsigned long mask[1];
16 };
17
18 struct rule {
19 uint8_t seqnum;
20 };
21
22 struct 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
29 struct 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
36 struct rules_map rules SEC(".maps");
37 struct tiers_map tiers SEC(".maps");
38
39 SEC("cgroup_skb/ingress")
twfw_verifier(struct __sk_buff * skb)40 int 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