1// SPDX-License-Identifier: GPL-2.0
2#include <linux/bpf.h>
3#include <bpf/bpf_helpers.h>
4#include <bpf/bpf_endian.h>
5
6#include <linux/ip.h>
7#include <linux/in.h>
8#include <linux/if_ether.h>
9#include <linux/pkt_cls.h>
10#include <stdbool.h>
11
12int lookup_status;
13bool test_xdp;
14bool tcp_skc;
15
16#define CUR_NS BPF_F_CURRENT_NETNS
17
18static void socket_lookup(void *ctx, void *data_end, void *data)
19{
20	struct ethhdr *eth = data;
21	struct bpf_sock_tuple *tp;
22	struct bpf_sock *sk;
23	struct iphdr *iph;
24	int tplen;
25
26	if (eth + 1 > data_end)
27		return;
28
29	if (eth->h_proto != bpf_htons(ETH_P_IP))
30		return;
31
32	iph = (struct iphdr *)(eth + 1);
33	if (iph + 1 > data_end)
34		return;
35
36	tp = (struct bpf_sock_tuple *)&iph->saddr;
37	tplen = sizeof(tp->ipv4);
38	if ((void *)tp + tplen > data_end)
39		return;
40
41	switch (iph->protocol) {
42	case IPPROTO_TCP:
43		if (tcp_skc)
44			sk = bpf_skc_lookup_tcp(ctx, tp, tplen, CUR_NS, 0);
45		else
46			sk = bpf_sk_lookup_tcp(ctx, tp, tplen, CUR_NS, 0);
47		break;
48	case IPPROTO_UDP:
49		sk = bpf_sk_lookup_udp(ctx, tp, tplen, CUR_NS, 0);
50		break;
51	default:
52		return;
53	}
54
55	lookup_status = 0;
56
57	if (sk) {
58		bpf_sk_release(sk);
59		lookup_status = 1;
60	}
61}
62
63SEC("tc")
64int tc_socket_lookup(struct __sk_buff *skb)
65{
66	void *data_end = (void *)(long)skb->data_end;
67	void *data = (void *)(long)skb->data;
68
69	if (test_xdp)
70		return TC_ACT_UNSPEC;
71
72	socket_lookup(skb, data_end, data);
73	return TC_ACT_UNSPEC;
74}
75
76SEC("xdp")
77int xdp_socket_lookup(struct xdp_md *xdp)
78{
79	void *data_end = (void *)(long)xdp->data_end;
80	void *data = (void *)(long)xdp->data;
81
82	if (!test_xdp)
83		return XDP_PASS;
84
85	socket_lookup(xdp, data_end, data);
86	return XDP_PASS;
87}
88
89char _license[] SEC("license") = "GPL";
90