1/* Copyright (c) 2017 Covalent IO, Inc. http://covalent.io
 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 * This program is distributed in the hope that it will be useful, but
 8 * WITHOUT ANY WARRANTY; without even the implied warranty of
 9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
10 * General Public License for more details.
11 */
12#define KBUILD_MODNAME "foo"
13#include <uapi/linux/bpf.h>
14#include <linux/in.h>
15#include <linux/if_ether.h>
16#include <linux/if_packet.h>
17#include <linux/if_vlan.h>
18#include <linux/ip.h>
19#include <linux/ipv6.h>
20#include "bpf_helpers.h"
21
22struct bpf_map_def SEC("maps") tx_port = {
23	.type = BPF_MAP_TYPE_DEVMAP,
24	.key_size = sizeof(int),
25	.value_size = sizeof(int),
26	.max_entries = 100,
27};
28
29/* Count RX packets, as XDP bpf_prog doesn't get direct TX-success
30 * feedback.  Redirect TX errors can be caught via a tracepoint.
31 */
32struct bpf_map_def SEC("maps") rxcnt = {
33	.type = BPF_MAP_TYPE_PERCPU_ARRAY,
34	.key_size = sizeof(u32),
35	.value_size = sizeof(long),
36	.max_entries = 1,
37};
38
39static void swap_src_dst_mac(void *data)
40{
41	unsigned short *p = data;
42	unsigned short dst[3];
43
44	dst[0] = p[0];
45	dst[1] = p[1];
46	dst[2] = p[2];
47	p[0] = p[3];
48	p[1] = p[4];
49	p[2] = p[5];
50	p[3] = dst[0];
51	p[4] = dst[1];
52	p[5] = dst[2];
53}
54
55SEC("xdp_redirect_map")
56int xdp_redirect_map_prog(struct xdp_md *ctx)
57{
58	void *data_end = (void *)(long)ctx->data_end;
59	void *data = (void *)(long)ctx->data;
60	struct ethhdr *eth = data;
61	int rc = XDP_DROP;
62	int vport, port = 0, m = 0;
63	long *value;
64	u32 key = 0;
65	u64 nh_off;
66
67	nh_off = sizeof(*eth);
68	if (data + nh_off > data_end)
69		return rc;
70
71	/* constant virtual port */
72	vport = 0;
73
74	/* count packet in global counter */
75	value = bpf_map_lookup_elem(&rxcnt, &key);
76	if (value)
77		*value += 1;
78
79	swap_src_dst_mac(data);
80
81	/* send packet out physical port */
82	return bpf_redirect_map(&tx_port, vport, 0);
83}
84
85/* Redirect require an XDP bpf_prog loaded on the TX device */
86SEC("xdp_redirect_dummy")
87int xdp_redirect_dummy_prog(struct xdp_md *ctx)
88{
89	return XDP_PASS;
90}
91
92char _license[] SEC("license") = "GPL";