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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_helpers.h"
16#include <linux/slab.h>
17#include <net/ip_fib.h>
18
19struct trie_value {
20 __u8 prefix[4];
21 __be64 value;
22 int ifindex;
23 int metric;
24 __be32 gw;
25};
26
27
28union key_4 {
29 u32 b32[2];
30 u8 b8[8];
31};
32
33struct arp_entry {
34 __be64 mac;
35 __be32 dst;
36};
37
38struct direct_map {
39 struct arp_entry arp;
40 int ifindex;
41 __be64 mac;
42};
43
44
45struct bpf_map_def SEC("maps") lpm_map = {
46 .type = BPF_MAP_TYPE_LPM_TRIE,
47 .key_size = 8,
48 .value_size = sizeof(struct trie_value),
49 .max_entries = 50,
50 .map_flags = BPF_F_NO_PREALLOC,
51};
52
53
54struct bpf_map_def SEC("maps") rxcnt = {
55 .type = BPF_MAP_TYPE_PERCPU_ARRAY,
56 .key_size = sizeof(u32),
57 .value_size = sizeof(u64),
58 .max_entries = 256,
59};
60
61
62struct bpf_map_def SEC("maps") arp_table = {
63 .type = BPF_MAP_TYPE_HASH,
64 .key_size = sizeof(__be32),
65 .value_size = sizeof(__be64),
66 .max_entries = 50,
67};
68
69
70struct bpf_map_def SEC("maps") exact_match = {
71 .type = BPF_MAP_TYPE_HASH,
72 .key_size = sizeof(__be32),
73 .value_size = sizeof(struct direct_map),
74 .max_entries = 50,
75};
76
77struct bpf_map_def SEC("maps") tx_port = {
78 .type = BPF_MAP_TYPE_DEVMAP,
79 .key_size = sizeof(int),
80 .value_size = sizeof(int),
81 .max_entries = 100,
82};
83
84
85static 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
96static 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
108SEC("xdp_router_ipv4")
109int 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
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
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
186char _license[] SEC("license") = "GPL";
187
