1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (c) 2022 Meta */
3#include <stddef.h>
4#include <string.h>
5#include <stdbool.h>
6#include <linux/bpf.h>
7#include <linux/if_ether.h>
8#include <linux/if_packet.h>
9#include <linux/ip.h>
10#include <linux/ipv6.h>
11#include <linux/in.h>
12#include <linux/udp.h>
13#include <linux/tcp.h>
14#include <linux/pkt_cls.h>
15#include <sys/socket.h>
16#include <bpf/bpf_helpers.h>
17#include <bpf/bpf_endian.h>
18#include "test_iptunnel_common.h"
19#include "bpf_kfuncs.h"
20
21#define tcphdr_sz sizeof(struct tcphdr)
22#define udphdr_sz sizeof(struct udphdr)
23#define ethhdr_sz sizeof(struct ethhdr)
24#define iphdr_sz sizeof(struct iphdr)
25#define ipv6hdr_sz sizeof(struct ipv6hdr)
26
27struct {
28 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
29 __uint(max_entries, 256);
30 __type(key, __u32);
31 __type(value, __u64);
32} rxcnt SEC(".maps");
33
34struct {
35 __uint(type, BPF_MAP_TYPE_HASH);
36 __uint(max_entries, MAX_IPTNL_ENTRIES);
37 __type(key, struct vip);
38 __type(value, struct iptnl_info);
39} vip2tnl SEC(".maps");
40
41static __always_inline void count_tx(__u32 protocol)
42{
43 __u64 *rxcnt_count;
44
45 rxcnt_count = bpf_map_lookup_elem(&rxcnt, &protocol);
46 if (rxcnt_count)
47 *rxcnt_count += 1;
48}
49
50static __always_inline int get_dport(void *trans_data, __u8 protocol)
51{
52 struct tcphdr *th;
53 struct udphdr *uh;
54
55 switch (protocol) {
56 case IPPROTO_TCP:
57 th = (struct tcphdr *)trans_data;
58 return th->dest;
59 case IPPROTO_UDP:
60 uh = (struct udphdr *)trans_data;
61 return uh->dest;
62 default:
63 return 0;
64 }
65}
66
67static __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
77static __always_inline int handle_ipv4(struct xdp_md *xdp, struct bpf_dynptr *xdp_ptr)
78{
79 __u8 eth_buffer[ethhdr_sz + iphdr_sz + ethhdr_sz];
80 __u8 iph_buffer_tcp[iphdr_sz + tcphdr_sz];
81 __u8 iph_buffer_udp[iphdr_sz + udphdr_sz];
82 struct bpf_dynptr new_xdp_ptr;
83 struct iptnl_info *tnl;
84 struct ethhdr *new_eth;
85 struct ethhdr *old_eth;
86 struct iphdr *iph;
87 __u16 *next_iph;
88 __u16 payload_len;
89 struct vip vip = {};
90 int dport;
91 __u32 csum = 0;
92 int i;
93
94 __builtin_memset(eth_buffer, 0, sizeof(eth_buffer));
95 __builtin_memset(iph_buffer_tcp, 0, sizeof(iph_buffer_tcp));
96 __builtin_memset(iph_buffer_udp, 0, sizeof(iph_buffer_udp));
97
98 if (ethhdr_sz + iphdr_sz + tcphdr_sz > xdp->data_end - xdp->data)
99 iph = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, iph_buffer_udp, sizeof(iph_buffer_udp));
100 else
101 iph = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, iph_buffer_tcp, sizeof(iph_buffer_tcp));
102
103 if (!iph)
104 return XDP_DROP;
105
106 dport = get_dport(trans_data: iph + 1, protocol: iph->protocol);
107 if (dport == -1)
108 return XDP_DROP;
109
110 vip.protocol = iph->protocol;
111 vip.family = AF_INET;
112 vip.daddr.v4 = iph->daddr;
113 vip.dport = dport;
114 payload_len = bpf_ntohs(iph->tot_len);
115
116 tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
117 /* It only does v4-in-v4 */
118 if (!tnl || tnl->family != AF_INET)
119 return XDP_PASS;
120
121 if (bpf_xdp_adjust_head(xdp, 0 - (int)iphdr_sz))
122 return XDP_DROP;
123
124 bpf_dynptr_from_xdp(xdp, 0, &new_xdp_ptr);
125 new_eth = bpf_dynptr_slice_rdwr(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer));
126 if (!new_eth)
127 return XDP_DROP;
128
129 iph = (struct iphdr *)(new_eth + 1);
130 old_eth = (struct ethhdr *)(iph + 1);
131
132 set_ethhdr(new_eth, old_eth, tnl, h_proto: bpf_htons(ETH_P_IP));
133
134 if (new_eth == eth_buffer)
135 bpf_dynptr_write(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer), 0);
136
137 iph->version = 4;
138 iph->ihl = iphdr_sz >> 2;
139 iph->frag_off = 0;
140 iph->protocol = IPPROTO_IPIP;
141 iph->check = 0;
142 iph->tos = 0;
143 iph->tot_len = bpf_htons(payload_len + iphdr_sz);
144 iph->daddr = tnl->daddr.v4;
145 iph->saddr = tnl->saddr.v4;
146 iph->ttl = 8;
147
148 next_iph = (__u16 *)iph;
149 for (i = 0; i < iphdr_sz >> 1; i++)
150 csum += *next_iph++;
151
152 iph->check = ~((csum & 0xffff) + (csum >> 16));
153
154 count_tx(protocol: vip.protocol);
155
156 return XDP_TX;
157}
158
159static __always_inline int handle_ipv6(struct xdp_md *xdp, struct bpf_dynptr *xdp_ptr)
160{
161 __u8 eth_buffer[ethhdr_sz + ipv6hdr_sz + ethhdr_sz];
162 __u8 ip6h_buffer_tcp[ipv6hdr_sz + tcphdr_sz];
163 __u8 ip6h_buffer_udp[ipv6hdr_sz + udphdr_sz];
164 struct bpf_dynptr new_xdp_ptr;
165 struct iptnl_info *tnl;
166 struct ethhdr *new_eth;
167 struct ethhdr *old_eth;
168 struct ipv6hdr *ip6h;
169 __u16 payload_len;
170 struct vip vip = {};
171 int dport;
172
173 __builtin_memset(eth_buffer, 0, sizeof(eth_buffer));
174 __builtin_memset(ip6h_buffer_tcp, 0, sizeof(ip6h_buffer_tcp));
175 __builtin_memset(ip6h_buffer_udp, 0, sizeof(ip6h_buffer_udp));
176
177 if (ethhdr_sz + iphdr_sz + tcphdr_sz > xdp->data_end - xdp->data)
178 ip6h = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, ip6h_buffer_udp, sizeof(ip6h_buffer_udp));
179 else
180 ip6h = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, ip6h_buffer_tcp, sizeof(ip6h_buffer_tcp));
181
182 if (!ip6h)
183 return XDP_DROP;
184
185 dport = get_dport(trans_data: ip6h + 1, protocol: ip6h->nexthdr);
186 if (dport == -1)
187 return XDP_DROP;
188
189 vip.protocol = ip6h->nexthdr;
190 vip.family = AF_INET6;
191 memcpy(vip.daddr.v6, ip6h->daddr.s6_addr32, sizeof(vip.daddr));
192 vip.dport = dport;
193 payload_len = ip6h->payload_len;
194
195 tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
196 /* It only does v6-in-v6 */
197 if (!tnl || tnl->family != AF_INET6)
198 return XDP_PASS;
199
200 if (bpf_xdp_adjust_head(xdp, 0 - (int)ipv6hdr_sz))
201 return XDP_DROP;
202
203 bpf_dynptr_from_xdp(xdp, 0, &new_xdp_ptr);
204 new_eth = bpf_dynptr_slice_rdwr(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer));
205 if (!new_eth)
206 return XDP_DROP;
207
208 ip6h = (struct ipv6hdr *)(new_eth + 1);
209 old_eth = (struct ethhdr *)(ip6h + 1);
210
211 set_ethhdr(new_eth, old_eth, tnl, h_proto: bpf_htons(ETH_P_IPV6));
212
213 if (new_eth == eth_buffer)
214 bpf_dynptr_write(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer), 0);
215
216 ip6h->version = 6;
217 ip6h->priority = 0;
218 memset(ip6h->flow_lbl, 0, sizeof(ip6h->flow_lbl));
219 ip6h->payload_len = bpf_htons(bpf_ntohs(payload_len) + ipv6hdr_sz);
220 ip6h->nexthdr = IPPROTO_IPV6;
221 ip6h->hop_limit = 8;
222 memcpy(ip6h->saddr.s6_addr32, tnl->saddr.v6, sizeof(tnl->saddr.v6));
223 memcpy(ip6h->daddr.s6_addr32, tnl->daddr.v6, sizeof(tnl->daddr.v6));
224
225 count_tx(protocol: vip.protocol);
226
227 return XDP_TX;
228}
229
230SEC("xdp")
231int _xdp_tx_iptunnel(struct xdp_md *xdp)
232{
233 __u8 buffer[ethhdr_sz];
234 struct bpf_dynptr ptr;
235 struct ethhdr *eth;
236 __u16 h_proto;
237
238 __builtin_memset(buffer, 0, sizeof(buffer));
239
240 bpf_dynptr_from_xdp(xdp, 0, &ptr);
241 eth = bpf_dynptr_slice(&ptr, 0, buffer, sizeof(buffer));
242 if (!eth)
243 return XDP_DROP;
244
245 h_proto = eth->h_proto;
246
247 if (h_proto == bpf_htons(ETH_P_IP))
248 return handle_ipv4(xdp, xdp_ptr: &ptr);
249 else if (h_proto == bpf_htons(ETH_P_IPV6))
250
251 return handle_ipv6(xdp, xdp_ptr: &ptr);
252 else
253 return XDP_DROP;
254}
255
256char _license[] SEC("license") = "GPL";
257

source code of linux/tools/testing/selftests/bpf/progs/test_xdp_dynptr.c