1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | |
3 | /* |
4 | * Copyright 2020 Google LLC. |
5 | */ |
6 | |
7 | #include <errno.h> |
8 | #include <linux/bpf.h> |
9 | #include <linux/if_ether.h> |
10 | #include <linux/ip.h> |
11 | #include <bpf/bpf_helpers.h> |
12 | |
13 | struct { |
14 | __uint(type, BPF_MAP_TYPE_ARRAY); |
15 | __uint(max_entries, 1); |
16 | __type(key, __u32); |
17 | __type(value, __u32); |
18 | } test_result SEC(".maps" ); |
19 | |
20 | SEC("cgroup_skb/egress" ) |
21 | int load_bytes_relative(struct __sk_buff *skb) |
22 | { |
23 | struct ethhdr eth; |
24 | struct iphdr iph; |
25 | |
26 | __u32 map_key = 0; |
27 | __u32 test_passed = 0; |
28 | |
29 | /* MAC header is not set by the time cgroup_skb/egress triggers */ |
30 | if (bpf_skb_load_bytes_relative(skb, 0, ð, sizeof(eth), |
31 | BPF_HDR_START_MAC) != -EFAULT) |
32 | goto fail; |
33 | |
34 | if (bpf_skb_load_bytes_relative(skb, 0, &iph, sizeof(iph), |
35 | BPF_HDR_START_NET)) |
36 | goto fail; |
37 | |
38 | if (bpf_skb_load_bytes_relative(skb, 0xffff, &iph, sizeof(iph), |
39 | BPF_HDR_START_NET) != -EFAULT) |
40 | goto fail; |
41 | |
42 | test_passed = 1; |
43 | |
44 | fail: |
45 | bpf_map_update_elem(&test_result, &map_key, &test_passed, BPF_ANY); |
46 | |
47 | return 1; |
48 | } |
49 | |