1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2022 Intel */
3 
4 #include <linux/bpf.h>
5 #include <bpf/bpf_helpers.h>
6 #include "xsk_xdp_metadata.h"
7 
8 struct {
9 	__uint(type, BPF_MAP_TYPE_XSKMAP);
10 	__uint(max_entries, 1);
11 	__uint(key_size, sizeof(int));
12 	__uint(value_size, sizeof(int));
13 } xsk SEC(".maps");
14 
15 static unsigned int idx;
16 int count = 0;
17 
18 SEC("xdp") int xsk_def_prog(struct xdp_md *xdp)
19 {
20 	return bpf_redirect_map(&xsk, 0, XDP_DROP);
21 }
22 
23 SEC("xdp") int xsk_xdp_drop(struct xdp_md *xdp)
24 {
25 	/* Drop every other packet */
26 	if (idx++ % 2)
27 		return XDP_DROP;
28 
29 	return bpf_redirect_map(&xsk, 0, XDP_DROP);
30 }
31 
32 SEC("xdp") int xsk_xdp_populate_metadata(struct xdp_md *xdp)
33 {
34 	void *data, *data_meta;
35 	struct xdp_info *meta;
36 	int err;
37 
38 	/* Reserve enough for all custom metadata. */
39 	err = bpf_xdp_adjust_meta(xdp, -(int)sizeof(struct xdp_info));
40 	if (err)
41 		return XDP_DROP;
42 
43 	data = (void *)(long)xdp->data;
44 	data_meta = (void *)(long)xdp->data_meta;
45 
46 	if (data_meta + sizeof(struct xdp_info) > data)
47 		return XDP_DROP;
48 
49 	meta = data_meta;
50 	meta->count = count++;
51 
52 	return bpf_redirect_map(&xsk, 0, XDP_DROP);
53 }
54 
55 char _license[] SEC("license") = "GPL";
56