1 | /* Copyright (c) 2016 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 | * This program shows how to use bpf_xdp_adjust_head() by |
8 | * encapsulating the incoming packet in an IPv4/v6 header |
9 | * and then XDP_TX it out. |
10 | */ |
11 | #define KBUILD_MODNAME "foo" |
12 | #include <uapi/linux/bpf.h> |
13 | #include <linux/in.h> |
14 | #include <linux/if_ether.h> |
15 | #include <linux/if_packet.h> |
16 | #include <linux/if_vlan.h> |
17 | #include <linux/ip.h> |
18 | #include <linux/ipv6.h> |
19 | #include <bpf/bpf_helpers.h> |
20 | #include "xdp_tx_iptunnel_common.h" |
21 | |
22 | struct { |
23 | __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); |
24 | __type(key, __u32); |
25 | __type(value, __u64); |
26 | __uint(max_entries, 256); |
27 | } rxcnt SEC(".maps" ); |
28 | |
29 | struct { |
30 | __uint(type, BPF_MAP_TYPE_HASH); |
31 | __type(key, struct vip); |
32 | __type(value, struct iptnl_info); |
33 | __uint(max_entries, MAX_IPTNL_ENTRIES); |
34 | } vip2tnl SEC(".maps" ); |
35 | |
36 | static __always_inline void count_tx(u32 protocol) |
37 | { |
38 | u64 *rxcnt_count; |
39 | |
40 | rxcnt_count = bpf_map_lookup_elem(&rxcnt, &protocol); |
41 | if (rxcnt_count) |
42 | *rxcnt_count += 1; |
43 | } |
44 | |
45 | static __always_inline int get_dport(void *trans_data, void *data_end, |
46 | u8 protocol) |
47 | { |
48 | struct tcphdr *th; |
49 | struct udphdr *uh; |
50 | |
51 | switch (protocol) { |
52 | case IPPROTO_TCP: |
53 | th = (struct tcphdr *)trans_data; |
54 | if (th + 1 > data_end) |
55 | return -1; |
56 | return th->dest; |
57 | case IPPROTO_UDP: |
58 | uh = (struct udphdr *)trans_data; |
59 | if (uh + 1 > data_end) |
60 | return -1; |
61 | return uh->dest; |
62 | default: |
63 | return 0; |
64 | } |
65 | } |
66 | |
67 | static __always_inline void set_ethhdr(struct ethhdr *new_eth, |
68 | const struct ethhdr *old_eth, |
69 | const struct iptnl_info *tnl, |
70 | __be16 h_proto) |
71 | { |
72 | memcpy(new_eth->h_source, old_eth->h_dest, sizeof(new_eth->h_source)); |
73 | memcpy(new_eth->h_dest, tnl->dmac, sizeof(new_eth->h_dest)); |
74 | new_eth->h_proto = h_proto; |
75 | } |
76 | |
77 | static __always_inline int handle_ipv4(struct xdp_md *xdp) |
78 | { |
79 | void *data_end = (void *)(long)xdp->data_end; |
80 | void *data = (void *)(long)xdp->data; |
81 | struct iptnl_info *tnl; |
82 | struct ethhdr *new_eth; |
83 | struct ethhdr *old_eth; |
84 | struct iphdr *iph = data + sizeof(struct ethhdr); |
85 | u16 *next_iph_u16; |
86 | u16 payload_len; |
87 | struct vip vip = {}; |
88 | int dport; |
89 | u32 csum = 0; |
90 | int i; |
91 | |
92 | if (iph + 1 > data_end) |
93 | return XDP_DROP; |
94 | |
95 | dport = get_dport(iph + 1, data_end, iph->protocol); |
96 | if (dport == -1) |
97 | return XDP_DROP; |
98 | |
99 | vip.protocol = iph->protocol; |
100 | vip.family = AF_INET; |
101 | vip.daddr.v4 = iph->daddr; |
102 | vip.dport = dport; |
103 | payload_len = ntohs(iph->tot_len); |
104 | |
105 | tnl = bpf_map_lookup_elem(&vip2tnl, &vip); |
106 | /* It only does v4-in-v4 */ |
107 | if (!tnl || tnl->family != AF_INET) |
108 | return XDP_PASS; |
109 | |
110 | /* The vip key is found. Add an IP header and send it out */ |
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, h_proto: 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 = 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 = (u16 *)iph; |
141 | #pragma clang loop unroll(full) |
142 | for (i = 0; i < sizeof(*iph) >> 1; i++) |
143 | csum += *next_iph_u16++; |
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 | /* The vip key is found. Add an IP header and send it out */ |
183 | |
184 | if (bpf_xdp_adjust_head(xdp, 0 - (int)sizeof(struct ipv6hdr))) |
185 | return XDP_DROP; |
186 | |
187 | data = (void *)(long)xdp->data; |
188 | data_end = (void *)(long)xdp->data_end; |
189 | |
190 | new_eth = data; |
191 | ip6h = data + sizeof(*new_eth); |
192 | old_eth = data + sizeof(*ip6h); |
193 | |
194 | if (new_eth + 1 > data_end || |
195 | old_eth + 1 > data_end || |
196 | ip6h + 1 > data_end) |
197 | return XDP_DROP; |
198 | |
199 | set_ethhdr(new_eth, old_eth, tnl, h_proto: htons(ETH_P_IPV6)); |
200 | |
201 | ip6h->version = 6; |
202 | ip6h->priority = 0; |
203 | memset(ip6h->flow_lbl, 0, sizeof(ip6h->flow_lbl)); |
204 | ip6h->payload_len = htons(ntohs(payload_len) + sizeof(*ip6h)); |
205 | ip6h->nexthdr = IPPROTO_IPV6; |
206 | ip6h->hop_limit = 8; |
207 | memcpy(ip6h->saddr.s6_addr32, tnl->saddr.v6, sizeof(tnl->saddr.v6)); |
208 | memcpy(ip6h->daddr.s6_addr32, tnl->daddr.v6, sizeof(tnl->daddr.v6)); |
209 | |
210 | count_tx(vip.protocol); |
211 | |
212 | return XDP_TX; |
213 | } |
214 | |
215 | SEC("xdp.frags" ) |
216 | int _xdp_tx_iptunnel(struct xdp_md *xdp) |
217 | { |
218 | void *data_end = (void *)(long)xdp->data_end; |
219 | void *data = (void *)(long)xdp->data; |
220 | struct ethhdr *eth = data; |
221 | __u16 h_proto; |
222 | |
223 | if (eth + 1 > data_end) |
224 | return XDP_DROP; |
225 | |
226 | h_proto = eth->h_proto; |
227 | |
228 | if (h_proto == htons(ETH_P_IP)) |
229 | return handle_ipv4(xdp); |
230 | else if (h_proto == htons(ETH_P_IPV6)) |
231 | |
232 | return handle_ipv6(xdp); |
233 | else |
234 | return XDP_PASS; |
235 | } |
236 | |
237 | char _license[] SEC("license" ) = "GPL" ; |
238 | |