1 /* Copyright (c) 2016,2017 Facebook
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 #include <stddef.h>
8 #include <string.h>
9 #include <linux/bpf.h>
10 #include <linux/if_ether.h>
11 #include <linux/if_packet.h>
12 #include <linux/ip.h>
13 #include <linux/ipv6.h>
14 #include <linux/in.h>
15 #include <linux/udp.h>
16 #include <linux/tcp.h>
17 #include <linux/pkt_cls.h>
18 #include <sys/socket.h>
19 #include <bpf/bpf_helpers.h>
20 #include <bpf/bpf_endian.h>
21 #include "test_iptunnel_common.h"
22 #include "bpf_compiler.h"
23
24 struct {
25 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
26 __uint(max_entries, 256);
27 __type(key, __u32);
28 __type(value, __u64);
29 } rxcnt SEC(".maps");
30
31 struct {
32 __uint(type, BPF_MAP_TYPE_HASH);
33 __uint(max_entries, MAX_IPTNL_ENTRIES);
34 __type(key, struct vip);
35 __type(value, struct iptnl_info);
36 } vip2tnl SEC(".maps");
37
38 static __always_inline void count_tx(__u32 protocol)
39 {
40 __u64 *rxcnt_count;
41
42 rxcnt_count = bpf_map_lookup_elem(&rxcnt, &protocol);
43 if (rxcnt_count)
44 *rxcnt_count += 1;
45 }
46
47 static __always_inline int get_dport(void *trans_data, void *data_end,
48 __u8 protocol)
49 {
50 struct tcphdr *th;
51 struct udphdr *uh;
52
53 switch (protocol) {
54 case IPPROTO_TCP:
55 th = (struct tcphdr *)trans_data;
56 if (th + 1 > data_end)
57 return -1;
58 return th->dest;
59 case IPPROTO_UDP:
60 uh = (struct udphdr *)trans_data;
61 if (uh + 1 > data_end)
62 return -1;
63 return uh->dest;
64 default:
65 return 0;
66 }
67 }
68
69 static __always_inline void set_ethhdr(struct ethhdr *new_eth,
70 const struct ethhdr *old_eth,
71 const struct iptnl_info *tnl,
72 __be16 h_proto)
73 {
74 memcpy(new_eth->h_source, old_eth->h_dest, sizeof(new_eth->h_source));
75 memcpy(new_eth->h_dest, tnl->dmac, sizeof(new_eth->h_dest));
76 new_eth->h_proto = h_proto;
77 }
78
79 static __always_inline int handle_ipv4(struct xdp_md *xdp)
80 {
81 void *data_end = (void *)(long)xdp->data_end;
82 void *data = (void *)(long)xdp->data;
83 struct iptnl_info *tnl;
84 struct ethhdr *new_eth;
85 struct ethhdr *old_eth;
86 struct iphdr *iph = data + sizeof(struct ethhdr);
87 __u16 *next_iph;
88 __u16 payload_len;
89 struct vip vip = {};
90 int dport;
91 __u32 csum = 0;
92 int i;
93
94 if (iph + 1 > data_end)
95 return XDP_DROP;
96
97 dport = get_dport(iph + 1, data_end, iph->protocol);
98 if (dport == -1)
99 return XDP_DROP;
100
101 vip.protocol = iph->protocol;
102 vip.family = AF_INET;
103 vip.daddr.v4 = iph->daddr;
104 vip.dport = dport;
105 payload_len = bpf_ntohs(iph->tot_len);
106
107 tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
108 /* It only does v4-in-v4 */
109 if (!tnl || tnl->family != AF_INET)
110 return XDP_PASS;
111
112 if (bpf_xdp_adjust_head(xdp, 0 - (int)sizeof(struct iphdr)))
113 return XDP_DROP;
114
115 data = (void *)(long)xdp->data;
116 data_end = (void *)(long)xdp->data_end;
117
118 new_eth = data;
119 iph = data + sizeof(*new_eth);
120 old_eth = data + sizeof(*iph);
121
122 if (new_eth + 1 > data_end ||
123 old_eth + 1 > data_end ||
124 iph + 1 > data_end)
125 return XDP_DROP;
126
127 set_ethhdr(new_eth, old_eth, tnl, bpf_htons(ETH_P_IP));
128
129 iph->version = 4;
130 iph->ihl = sizeof(*iph) >> 2;
131 iph->frag_off = 0;
132 iph->protocol = IPPROTO_IPIP;
133 iph->check = 0;
134 iph->tos = 0;
135 iph->tot_len = bpf_htons(payload_len + sizeof(*iph));
136 iph->daddr = tnl->daddr.v4;
137 iph->saddr = tnl->saddr.v4;
138 iph->ttl = 8;
139
140 next_iph = (__u16 *)iph;
141 __pragma_loop_unroll_full
142 for (i = 0; i < sizeof(*iph) >> 1; i++)
143 csum += *next_iph++;
144
145 iph->check = ~((csum & 0xffff) + (csum >> 16));
146
147 count_tx(vip.protocol);
148
149 return XDP_TX;
150 }
151
152 static __always_inline int handle_ipv6(struct xdp_md *xdp)
153 {
154 void *data_end = (void *)(long)xdp->data_end;
155 void *data = (void *)(long)xdp->data;
156 struct iptnl_info *tnl;
157 struct ethhdr *new_eth;
158 struct ethhdr *old_eth;
159 struct ipv6hdr *ip6h = data + sizeof(struct ethhdr);
160 __u16 payload_len;
161 struct vip vip = {};
162 int dport;
163
164 if (ip6h + 1 > data_end)
165 return XDP_DROP;
166
167 dport = get_dport(ip6h + 1, data_end, ip6h->nexthdr);
168 if (dport == -1)
169 return XDP_DROP;
170
171 vip.protocol = ip6h->nexthdr;
172 vip.family = AF_INET6;
173 memcpy(vip.daddr.v6, ip6h->daddr.s6_addr32, sizeof(vip.daddr));
174 vip.dport = dport;
175 payload_len = ip6h->payload_len;
176
177 tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
178 /* It only does v6-in-v6 */
179 if (!tnl || tnl->family != AF_INET6)
180 return XDP_PASS;
181
182 if (bpf_xdp_adjust_head(xdp, 0 - (int)sizeof(struct ipv6hdr)))
183 return XDP_DROP;
184
185 data = (void *)(long)xdp->data;
186 data_end = (void *)(long)xdp->data_end;
187
188 new_eth = data;
189 ip6h = data + sizeof(*new_eth);
190 old_eth = data + sizeof(*ip6h);
191
192 if (new_eth + 1 > data_end || old_eth + 1 > data_end ||
193 ip6h + 1 > data_end)
194 return XDP_DROP;
195
196 set_ethhdr(new_eth, old_eth, tnl, bpf_htons(ETH_P_IPV6));
197
198 ip6h->version = 6;
199 ip6h->priority = 0;
200 memset(ip6h->flow_lbl, 0, sizeof(ip6h->flow_lbl));
201 ip6h->payload_len = bpf_htons(bpf_ntohs(payload_len) + sizeof(*ip6h));
202 ip6h->nexthdr = IPPROTO_IPV6;
203 ip6h->hop_limit = 8;
204 memcpy(ip6h->saddr.s6_addr32, tnl->saddr.v6, sizeof(tnl->saddr.v6));
205 memcpy(ip6h->daddr.s6_addr32, tnl->daddr.v6, sizeof(tnl->daddr.v6));
206
207 count_tx(vip.protocol);
208
209 return XDP_TX;
210 }
211
212 SEC("xdp")
213 int _xdp_tx_iptunnel(struct xdp_md *xdp)
214 {
215 void *data_end = (void *)(long)xdp->data_end;
216 void *data = (void *)(long)xdp->data;
217 struct ethhdr *eth = data;
218 __u16 h_proto;
219
220 if (eth + 1 > data_end)
221 return XDP_DROP;
222
223 h_proto = eth->h_proto;
224
225 if (h_proto == bpf_htons(ETH_P_IP))
226 return handle_ipv4(xdp);
227 else if (h_proto == bpf_htons(ETH_P_IPV6))
228
229 return handle_ipv6(xdp);
230 else
231 return XDP_DROP;
232 }
233
234 char _license[] SEC("license") = "GPL";
235
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