1 /* Copyright (C) 2017 Cavium, Inc.
2 *
3 * This program is free software; you can redistribute it and/or modify it
4 * under the terms of version 2 of the GNU General Public License
5 * 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 #include <linux/slab.h>
17 #include <net/ip_fib.h>
18
19 struct trie_value {
20 __u8 prefix[4];
21 __be64 value;
22 int ifindex;
23 int metric;
24 __be32 gw;
25 };
26
27 /* Key for lpm_trie*/
28 union key_4 {
29 u32 b32[2];
30 u8 b8[8];
31 };
32
33 struct arp_entry {
34 __be64 mac;
35 __be32 dst;
36 };
37
38 struct direct_map {
39 struct arp_entry arp;
40 int ifindex;
41 __be64 mac;
42 };
43
44 /* Map for trie implementation*/
45 struct {
46 __uint(type, BPF_MAP_TYPE_LPM_TRIE);
47 __uint(key_size, 8);
48 __uint(value_size, sizeof(struct trie_value));
49 __uint(max_entries, 50);
50 __uint(map_flags, BPF_F_NO_PREALLOC);
51 } lpm_map SEC(".maps");
52
53 /* Map for counter*/
54 struct {
55 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
56 __type(key, u32);
57 __type(value, u64);
58 __uint(max_entries, 256);
59 } rxcnt SEC(".maps");
60
61 /* Map for ARP table*/
62 struct {
63 __uint(type, BPF_MAP_TYPE_HASH);
64 __type(key, __be32);
65 __type(value, __be64);
66 __uint(max_entries, 50);
67 } arp_table SEC(".maps");
68
69 /* Map to keep the exact match entries in the route table*/
70 struct {
71 __uint(type, BPF_MAP_TYPE_HASH);
72 __type(key, __be32);
73 __type(value, struct direct_map);
74 __uint(max_entries, 50);
75 } exact_match SEC(".maps");
76
77 struct {
78 __uint(type, BPF_MAP_TYPE_DEVMAP);
79 __uint(key_size, sizeof(int));
80 __uint(value_size, sizeof(int));
81 __uint(max_entries, 100);
82 } tx_port SEC(".maps");
83
84 /* Function to set source and destination mac of the packet */
set_src_dst_mac(void * data,void * src,void * dst)85 static inline void set_src_dst_mac(void *data, void *src, void *dst)
86 {
87 unsigned short *source = src;
88 unsigned short *dest = dst;
89 unsigned short *p = data;
90
91 __builtin_memcpy(p, dest, 6);
92 __builtin_memcpy(p + 3, source, 6);
93 }
94
95 /* Parse IPV4 packet to get SRC, DST IP and protocol */
parse_ipv4(void * data,u64 nh_off,void * data_end,__be32 * src,__be32 * dest)96 static inline int parse_ipv4(void *data, u64 nh_off, void *data_end,
97 __be32 *src, __be32 *dest)
98 {
99 struct iphdr *iph = data + nh_off;
100
101 if (iph + 1 > data_end)
102 return 0;
103 *src = iph->saddr;
104 *dest = iph->daddr;
105 return iph->protocol;
106 }
107
108 SEC("xdp_router_ipv4")
xdp_router_ipv4_prog(struct xdp_md * ctx)109 int xdp_router_ipv4_prog(struct xdp_md *ctx)
110 {
111 void *data_end = (void *)(long)ctx->data_end;
112 __be64 *dest_mac = NULL, *src_mac = NULL;
113 void *data = (void *)(long)ctx->data;
114 struct trie_value *prefix_value;
115 int rc = XDP_DROP, forward_to;
116 struct ethhdr *eth = data;
117 union key_4 key4;
118 long *value;
119 u16 h_proto;
120 u32 ipproto;
121 u64 nh_off;
122
123 nh_off = sizeof(*eth);
124 if (data + nh_off > data_end)
125 return rc;
126
127 h_proto = eth->h_proto;
128
129 if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
130 struct vlan_hdr *vhdr;
131
132 vhdr = data + nh_off;
133 nh_off += sizeof(struct vlan_hdr);
134 if (data + nh_off > data_end)
135 return rc;
136 h_proto = vhdr->h_vlan_encapsulated_proto;
137 }
138 if (h_proto == htons(ETH_P_ARP)) {
139 return XDP_PASS;
140 } else if (h_proto == htons(ETH_P_IP)) {
141 struct direct_map *direct_entry;
142 __be32 src_ip = 0, dest_ip = 0;
143
144 ipproto = parse_ipv4(data, nh_off, data_end, &src_ip, &dest_ip);
145 direct_entry = bpf_map_lookup_elem(&exact_match, &dest_ip);
146 /* Check for exact match, this would give a faster lookup*/
147 if (direct_entry && direct_entry->mac && direct_entry->arp.mac) {
148 src_mac = &direct_entry->mac;
149 dest_mac = &direct_entry->arp.mac;
150 forward_to = direct_entry->ifindex;
151 } else {
152 /* Look up in the trie for lpm*/
153 key4.b32[0] = 32;
154 key4.b8[4] = dest_ip & 0xff;
155 key4.b8[5] = (dest_ip >> 8) & 0xff;
156 key4.b8[6] = (dest_ip >> 16) & 0xff;
157 key4.b8[7] = (dest_ip >> 24) & 0xff;
158 prefix_value = bpf_map_lookup_elem(&lpm_map, &key4);
159 if (!prefix_value)
160 return XDP_DROP;
161 src_mac = &prefix_value->value;
162 if (!src_mac)
163 return XDP_DROP;
164 dest_mac = bpf_map_lookup_elem(&arp_table, &dest_ip);
165 if (!dest_mac) {
166 if (!prefix_value->gw)
167 return XDP_DROP;
168 dest_ip = prefix_value->gw;
169 dest_mac = bpf_map_lookup_elem(&arp_table, &dest_ip);
170 }
171 forward_to = prefix_value->ifindex;
172 }
173 } else {
174 ipproto = 0;
175 }
176 if (src_mac && dest_mac) {
177 set_src_dst_mac(data, src_mac, dest_mac);
178 value = bpf_map_lookup_elem(&rxcnt, &ipproto);
179 if (value)
180 *value += 1;
181 return bpf_redirect_map(&tx_port, forward_to, 0);
182 }
183 return rc;
184 }
185
186 char _license[] SEC("license") = "GPL";
187