1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (c) 2019 Facebook
3 #include <stddef.h>
4 #include <string.h>
5 #include <linux/bpf.h>
6 #include <linux/if_ether.h>
7 #include <linux/if_packet.h>
8 #include <linux/ip.h>
9 #include <linux/ipv6.h>
10 #include <linux/in.h>
11 #include <linux/udp.h>
12 #include <linux/tcp.h>
13 #include <linux/pkt_cls.h>
14 #include <sys/socket.h>
15 #include <bpf/bpf_helpers.h>
16 #include <bpf/bpf_endian.h>
17 #include "test_iptunnel_common.h"
18
19 struct {
20 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
21 __uint(max_entries, 256);
22 __type(key, __u32);
23 __type(value, __u64);
24 } rxcnt SEC(".maps");
25
26 struct {
27 __uint(type, BPF_MAP_TYPE_HASH);
28 __uint(max_entries, MAX_IPTNL_ENTRIES);
29 __type(key, struct vip);
30 __type(value, struct iptnl_info);
31 } vip2tnl SEC(".maps");
32
count_tx(__u32 protocol)33 static __always_inline void count_tx(__u32 protocol)
34 {
35 __u64 *rxcnt_count;
36
37 rxcnt_count = bpf_map_lookup_elem(&rxcnt, &protocol);
38 if (rxcnt_count)
39 *rxcnt_count += 1;
40 }
41
get_dport(void * trans_data,void * data_end,__u8 protocol)42 static __always_inline int get_dport(void *trans_data, void *data_end,
43 __u8 protocol)
44 {
45 struct tcphdr *th;
46 struct udphdr *uh;
47
48 switch (protocol) {
49 case IPPROTO_TCP:
50 th = (struct tcphdr *)trans_data;
51 if (th + 1 > data_end)
52 return -1;
53 return th->dest;
54 case IPPROTO_UDP:
55 uh = (struct udphdr *)trans_data;
56 if (uh + 1 > data_end)
57 return -1;
58 return uh->dest;
59 default:
60 return 0;
61 }
62 }
63
set_ethhdr(struct ethhdr * new_eth,const struct ethhdr * old_eth,const struct iptnl_info * tnl,__be16 h_proto)64 static __always_inline void set_ethhdr(struct ethhdr *new_eth,
65 const struct ethhdr *old_eth,
66 const struct iptnl_info *tnl,
67 __be16 h_proto)
68 {
69 memcpy(new_eth->h_source, old_eth->h_dest, sizeof(new_eth->h_source));
70 memcpy(new_eth->h_dest, tnl->dmac, sizeof(new_eth->h_dest));
71 new_eth->h_proto = h_proto;
72 }
73
handle_ipv4(struct xdp_md * xdp)74 static __always_inline int handle_ipv4(struct xdp_md *xdp)
75 {
76 void *data_end = (void *)(long)xdp->data_end;
77 void *data = (void *)(long)xdp->data;
78 struct iptnl_info *tnl;
79 struct ethhdr *new_eth;
80 struct ethhdr *old_eth;
81 struct iphdr *iph = data + sizeof(struct ethhdr);
82 __u16 *next_iph;
83 __u16 payload_len;
84 struct vip vip = {};
85 int dport;
86 __u32 csum = 0;
87 int i;
88
89 if (iph + 1 > data_end)
90 return XDP_DROP;
91
92 dport = get_dport(iph + 1, data_end, iph->protocol);
93 if (dport == -1)
94 return XDP_DROP;
95
96 vip.protocol = iph->protocol;
97 vip.family = AF_INET;
98 vip.daddr.v4 = iph->daddr;
99 vip.dport = dport;
100 payload_len = bpf_ntohs(iph->tot_len);
101
102 tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
103 /* It only does v4-in-v4 */
104 if (!tnl || tnl->family != AF_INET)
105 return XDP_PASS;
106
107 if (bpf_xdp_adjust_head(xdp, 0 - (int)sizeof(struct iphdr)))
108 return XDP_DROP;
109
110 data = (void *)(long)xdp->data;
111 data_end = (void *)(long)xdp->data_end;
112
113 new_eth = data;
114 iph = data + sizeof(*new_eth);
115 old_eth = data + sizeof(*iph);
116
117 if (new_eth + 1 > data_end ||
118 old_eth + 1 > data_end ||
119 iph + 1 > data_end)
120 return XDP_DROP;
121
122 set_ethhdr(new_eth, old_eth, tnl, bpf_htons(ETH_P_IP));
123
124 iph->version = 4;
125 iph->ihl = sizeof(*iph) >> 2;
126 iph->frag_off = 0;
127 iph->protocol = IPPROTO_IPIP;
128 iph->check = 0;
129 iph->tos = 0;
130 iph->tot_len = bpf_htons(payload_len + sizeof(*iph));
131 iph->daddr = tnl->daddr.v4;
132 iph->saddr = tnl->saddr.v4;
133 iph->ttl = 8;
134
135 next_iph = (__u16 *)iph;
136 #pragma clang loop unroll(disable)
137 for (i = 0; i < sizeof(*iph) >> 1; i++)
138 csum += *next_iph++;
139
140 iph->check = ~((csum & 0xffff) + (csum >> 16));
141
142 count_tx(vip.protocol);
143
144 return XDP_TX;
145 }
146
handle_ipv6(struct xdp_md * xdp)147 static __always_inline int handle_ipv6(struct xdp_md *xdp)
148 {
149 void *data_end = (void *)(long)xdp->data_end;
150 void *data = (void *)(long)xdp->data;
151 struct iptnl_info *tnl;
152 struct ethhdr *new_eth;
153 struct ethhdr *old_eth;
154 struct ipv6hdr *ip6h = data + sizeof(struct ethhdr);
155 __u16 payload_len;
156 struct vip vip = {};
157 int dport;
158
159 if (ip6h + 1 > data_end)
160 return XDP_DROP;
161
162 dport = get_dport(ip6h + 1, data_end, ip6h->nexthdr);
163 if (dport == -1)
164 return XDP_DROP;
165
166 vip.protocol = ip6h->nexthdr;
167 vip.family = AF_INET6;
168 memcpy(vip.daddr.v6, ip6h->daddr.s6_addr32, sizeof(vip.daddr));
169 vip.dport = dport;
170 payload_len = ip6h->payload_len;
171
172 tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
173 /* It only does v6-in-v6 */
174 if (!tnl || tnl->family != AF_INET6)
175 return XDP_PASS;
176
177 if (bpf_xdp_adjust_head(xdp, 0 - (int)sizeof(struct ipv6hdr)))
178 return XDP_DROP;
179
180 data = (void *)(long)xdp->data;
181 data_end = (void *)(long)xdp->data_end;
182
183 new_eth = data;
184 ip6h = data + sizeof(*new_eth);
185 old_eth = data + sizeof(*ip6h);
186
187 if (new_eth + 1 > data_end || old_eth + 1 > data_end ||
188 ip6h + 1 > data_end)
189 return XDP_DROP;
190
191 set_ethhdr(new_eth, old_eth, tnl, bpf_htons(ETH_P_IPV6));
192
193 ip6h->version = 6;
194 ip6h->priority = 0;
195 memset(ip6h->flow_lbl, 0, sizeof(ip6h->flow_lbl));
196 ip6h->payload_len = bpf_htons(bpf_ntohs(payload_len) + sizeof(*ip6h));
197 ip6h->nexthdr = IPPROTO_IPV6;
198 ip6h->hop_limit = 8;
199 memcpy(ip6h->saddr.s6_addr32, tnl->saddr.v6, sizeof(tnl->saddr.v6));
200 memcpy(ip6h->daddr.s6_addr32, tnl->daddr.v6, sizeof(tnl->daddr.v6));
201
202 count_tx(vip.protocol);
203
204 return XDP_TX;
205 }
206
207 SEC("xdp")
_xdp_tx_iptunnel(struct xdp_md * xdp)208 int _xdp_tx_iptunnel(struct xdp_md *xdp)
209 {
210 void *data_end = (void *)(long)xdp->data_end;
211 void *data = (void *)(long)xdp->data;
212 struct ethhdr *eth = data;
213 __u16 h_proto;
214
215 if (eth + 1 > data_end)
216 return XDP_DROP;
217
218 h_proto = eth->h_proto;
219
220 if (h_proto == bpf_htons(ETH_P_IP))
221 return handle_ipv4(xdp);
222 else if (h_proto == bpf_htons(ETH_P_IPV6))
223
224 return handle_ipv6(xdp);
225 else
226 return XDP_DROP;
227 }
228
229 char _license[] SEC("license") = "GPL";
230