1 /* Copyright (c) 2016 PLUMgrid
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 <uapi/linux/bpf.h>
9 #include <linux/in.h>
10 #include <linux/if_ether.h>
11 #include <linux/if_packet.h>
12 #include <linux/if_vlan.h>
13 #include <linux/ip.h>
14 #include <linux/ipv6.h>
15 #include <bpf/bpf_helpers.h>
16
17 struct {
18 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
19 __type(key, u32);
20 __type(value, long);
21 __uint(max_entries, 256);
22 } rxcnt SEC(".maps");
23
swap_src_dst_mac(void * data)24 static void swap_src_dst_mac(void *data)
25 {
26 unsigned short *p = data;
27 unsigned short dst[3];
28
29 dst[0] = p[0];
30 dst[1] = p[1];
31 dst[2] = p[2];
32 p[0] = p[3];
33 p[1] = p[4];
34 p[2] = p[5];
35 p[3] = dst[0];
36 p[4] = dst[1];
37 p[5] = dst[2];
38 }
39
parse_ipv4(void * data,u64 nh_off,void * data_end)40 static int parse_ipv4(void *data, u64 nh_off, void *data_end)
41 {
42 struct iphdr *iph = data + nh_off;
43
44 if (iph + 1 > data_end)
45 return 0;
46 return iph->protocol;
47 }
48
parse_ipv6(void * data,u64 nh_off,void * data_end)49 static int parse_ipv6(void *data, u64 nh_off, void *data_end)
50 {
51 struct ipv6hdr *ip6h = data + nh_off;
52
53 if (ip6h + 1 > data_end)
54 return 0;
55 return ip6h->nexthdr;
56 }
57
58 #define XDPBUFSIZE 64
59 SEC("xdp.frags")
xdp_prog1(struct xdp_md * ctx)60 int xdp_prog1(struct xdp_md *ctx)
61 {
62 __u8 pkt[XDPBUFSIZE] = {};
63 void *data_end = &pkt[XDPBUFSIZE-1];
64 void *data = pkt;
65 struct ethhdr *eth = data;
66 int rc = XDP_DROP;
67 long *value;
68 u16 h_proto;
69 u64 nh_off;
70 u32 ipproto;
71
72 if (bpf_xdp_load_bytes(ctx, 0, pkt, sizeof(pkt)))
73 return rc;
74
75 nh_off = sizeof(*eth);
76 if (data + nh_off > data_end)
77 return rc;
78
79 h_proto = eth->h_proto;
80
81 /* Handle VLAN tagged packet */
82 if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
83 struct vlan_hdr *vhdr;
84
85 vhdr = data + nh_off;
86 nh_off += sizeof(struct vlan_hdr);
87 if (data + nh_off > data_end)
88 return rc;
89 h_proto = vhdr->h_vlan_encapsulated_proto;
90 }
91 /* Handle double VLAN tagged packet */
92 if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
93 struct vlan_hdr *vhdr;
94
95 vhdr = data + nh_off;
96 nh_off += sizeof(struct vlan_hdr);
97 if (data + nh_off > data_end)
98 return rc;
99 h_proto = vhdr->h_vlan_encapsulated_proto;
100 }
101
102 if (h_proto == htons(ETH_P_IP))
103 ipproto = parse_ipv4(data, nh_off, data_end);
104 else if (h_proto == htons(ETH_P_IPV6))
105 ipproto = parse_ipv6(data, nh_off, data_end);
106 else
107 ipproto = 0;
108
109 value = bpf_map_lookup_elem(&rxcnt, &ipproto);
110 if (value)
111 *value += 1;
112
113 if (ipproto == IPPROTO_UDP) {
114 swap_src_dst_mac(data);
115
116 if (bpf_xdp_store_bytes(ctx, 0, pkt, sizeof(pkt)))
117 return rc;
118
119 rc = XDP_TX;
120 }
121
122 return rc;
123 }
124
125 char _license[] SEC("license") = "GPL";
126