1 /* Copyright (c) 2016 Facebook
2 *
3 * This program is free software; you can redistribute it and/or
4 * modify it under the terms of version 2 of the GNU General Public
5 * License as published by the Free Software Foundation.
6 */
7 #define KBUILD_MODNAME "foo"
8 #include "vmlinux.h"
9 #include "net_shared.h"
10 #include <bpf/bpf_helpers.h>
11
12 /* copy of 'struct ethhdr' without __packed */
13 struct eth_hdr {
14 unsigned char h_dest[ETH_ALEN];
15 unsigned char h_source[ETH_ALEN];
16 unsigned short h_proto;
17 };
18
19 struct {
20 __uint(type, BPF_MAP_TYPE_CGROUP_ARRAY);
21 __type(key, u32);
22 __type(value, u32);
23 __uint(pinning, LIBBPF_PIN_BY_NAME);
24 __uint(max_entries, 1);
25 } test_cgrp2_array_pin SEC(".maps");
26
27 SEC("filter")
28 int handle_egress(struct __sk_buff *skb)
29 {
30 void *data = (void *)(long)skb->data;
31 struct eth_hdr *eth = data;
32 struct ipv6hdr *ip6h = data + sizeof(*eth);
33 void *data_end = (void *)(long)skb->data_end;
34 char dont_care_msg[] = "dont care %04x %d\n";
35 char pass_msg[] = "pass\n";
36 char reject_msg[] = "reject\n";
37
38 /* single length check */
39 if (data + sizeof(*eth) + sizeof(*ip6h) > data_end)
40 return TC_ACT_OK;
41
42 if (eth->h_proto != bpf_htons(ETH_P_IPV6) ||
43 ip6h->nexthdr != IPPROTO_ICMPV6) {
44 bpf_trace_printk(dont_care_msg, sizeof(dont_care_msg),
45 eth->h_proto, ip6h->nexthdr);
46 return TC_ACT_OK;
47 } else if (bpf_skb_under_cgroup(skb, &test_cgrp2_array_pin, 0) != 1) {
48 bpf_trace_printk(pass_msg, sizeof(pass_msg));
49 return TC_ACT_OK;
50 } else {
51 bpf_trace_printk(reject_msg, sizeof(reject_msg));
52 return TC_ACT_SHOT;
53 }
54 }
55
56 char _license[] SEC("license") = "GPL";
57
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