1// SPDX-License-Identifier: GPL-2.0-only
2/* tunnel4.c: Generic IP tunnel transformer.
3 *
4 * Copyright (C) 2003 David S. Miller (davem@redhat.com)
5 */
6
7#include <linux/init.h>
8#include <linux/module.h>
9#include <linux/mutex.h>
10#include <linux/mpls.h>
11#include <linux/netdevice.h>
12#include <linux/skbuff.h>
13#include <linux/slab.h>
14#include <net/icmp.h>
15#include <net/ip.h>
16#include <net/protocol.h>
17#include <net/xfrm.h>
18
19static struct xfrm_tunnel __rcu *tunnel4_handlers __read_mostly;
20static struct xfrm_tunnel __rcu *tunnel64_handlers __read_mostly;
21static struct xfrm_tunnel __rcu *tunnelmpls4_handlers __read_mostly;
22static DEFINE_MUTEX(tunnel4_mutex);
23
24static inline struct xfrm_tunnel __rcu **fam_handlers(unsigned short family)
25{
26 return (family == AF_INET) ? &tunnel4_handlers :
27 (family == AF_INET6) ? &tunnel64_handlers :
28 &tunnelmpls4_handlers;
29}
30
31int xfrm4_tunnel_register(struct xfrm_tunnel *handler, unsigned short family)
32{
33 struct xfrm_tunnel __rcu **pprev;
34 struct xfrm_tunnel *t;
35
36 int ret = -EEXIST;
37 int priority = handler->priority;
38
39 mutex_lock(lock: &tunnel4_mutex);
40
41 for (pprev = fam_handlers(family);
42 (t = rcu_dereference_protected(*pprev,
43 lockdep_is_held(&tunnel4_mutex))) != NULL;
44 pprev = &t->next) {
45 if (t->priority > priority)
46 break;
47 if (t->priority == priority)
48 goto err;
49 }
50
51 handler->next = *pprev;
52 rcu_assign_pointer(*pprev, handler);
53
54 ret = 0;
55
56err:
57 mutex_unlock(lock: &tunnel4_mutex);
58
59 return ret;
60}
61EXPORT_SYMBOL(xfrm4_tunnel_register);
62
63int xfrm4_tunnel_deregister(struct xfrm_tunnel *handler, unsigned short family)
64{
65 struct xfrm_tunnel __rcu **pprev;
66 struct xfrm_tunnel *t;
67 int ret = -ENOENT;
68
69 mutex_lock(lock: &tunnel4_mutex);
70
71 for (pprev = fam_handlers(family);
72 (t = rcu_dereference_protected(*pprev,
73 lockdep_is_held(&tunnel4_mutex))) != NULL;
74 pprev = &t->next) {
75 if (t == handler) {
76 *pprev = handler->next;
77 ret = 0;
78 break;
79 }
80 }
81
82 mutex_unlock(lock: &tunnel4_mutex);
83
84 synchronize_net();
85
86 return ret;
87}
88EXPORT_SYMBOL(xfrm4_tunnel_deregister);
89
90#define for_each_tunnel_rcu(head, handler) \
91 for (handler = rcu_dereference(head); \
92 handler != NULL; \
93 handler = rcu_dereference(handler->next)) \
94
95static int tunnel4_rcv(struct sk_buff *skb)
96{
97 struct xfrm_tunnel *handler;
98
99 if (!pskb_may_pull(skb, len: sizeof(struct iphdr)))
100 goto drop;
101
102 for_each_tunnel_rcu(tunnel4_handlers, handler)
103 if (!handler->handler(skb))
104 return 0;
105
106 icmp_send(skb_in: skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, info: 0);
107
108drop:
109 kfree_skb(skb);
110 return 0;
111}
112
113#if IS_ENABLED(CONFIG_INET_XFRM_TUNNEL)
114static int tunnel4_rcv_cb(struct sk_buff *skb, u8 proto, int err)
115{
116 struct xfrm_tunnel __rcu *head;
117 struct xfrm_tunnel *handler;
118 int ret;
119
120 head = (proto == IPPROTO_IPIP) ? tunnel4_handlers : tunnel64_handlers;
121
122 for_each_tunnel_rcu(head, handler) {
123 if (handler->cb_handler) {
124 ret = handler->cb_handler(skb, err);
125 if (ret <= 0)
126 return ret;
127 }
128 }
129
130 return 0;
131}
132
133static const struct xfrm_input_afinfo tunnel4_input_afinfo = {
134 .family = AF_INET,
135 .is_ipip = true,
136 .callback = tunnel4_rcv_cb,
137};
138#endif
139
140#if IS_ENABLED(CONFIG_IPV6)
141static int tunnel64_rcv(struct sk_buff *skb)
142{
143 struct xfrm_tunnel *handler;
144
145 if (!pskb_may_pull(skb, len: sizeof(struct ipv6hdr)))
146 goto drop;
147
148 for_each_tunnel_rcu(tunnel64_handlers, handler)
149 if (!handler->handler(skb))
150 return 0;
151
152 icmp_send(skb_in: skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, info: 0);
153
154drop:
155 kfree_skb(skb);
156 return 0;
157}
158#endif
159
160#if IS_ENABLED(CONFIG_MPLS)
161static int tunnelmpls4_rcv(struct sk_buff *skb)
162{
163 struct xfrm_tunnel *handler;
164
165 if (!pskb_may_pull(skb, sizeof(struct mpls_label)))
166 goto drop;
167
168 for_each_tunnel_rcu(tunnelmpls4_handlers, handler)
169 if (!handler->handler(skb))
170 return 0;
171
172 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
173
174drop:
175 kfree_skb(skb);
176 return 0;
177}
178#endif
179
180static int tunnel4_err(struct sk_buff *skb, u32 info)
181{
182 struct xfrm_tunnel *handler;
183
184 for_each_tunnel_rcu(tunnel4_handlers, handler)
185 if (!handler->err_handler(skb, info))
186 return 0;
187
188 return -ENOENT;
189}
190
191#if IS_ENABLED(CONFIG_IPV6)
192static int tunnel64_err(struct sk_buff *skb, u32 info)
193{
194 struct xfrm_tunnel *handler;
195
196 for_each_tunnel_rcu(tunnel64_handlers, handler)
197 if (!handler->err_handler(skb, info))
198 return 0;
199
200 return -ENOENT;
201}
202#endif
203
204#if IS_ENABLED(CONFIG_MPLS)
205static int tunnelmpls4_err(struct sk_buff *skb, u32 info)
206{
207 struct xfrm_tunnel *handler;
208
209 for_each_tunnel_rcu(tunnelmpls4_handlers, handler)
210 if (!handler->err_handler(skb, info))
211 return 0;
212
213 return -ENOENT;
214}
215#endif
216
217static const struct net_protocol tunnel4_protocol = {
218 .handler = tunnel4_rcv,
219 .err_handler = tunnel4_err,
220 .no_policy = 1,
221};
222
223#if IS_ENABLED(CONFIG_IPV6)
224static const struct net_protocol tunnel64_protocol = {
225 .handler = tunnel64_rcv,
226 .err_handler = tunnel64_err,
227 .no_policy = 1,
228};
229#endif
230
231#if IS_ENABLED(CONFIG_MPLS)
232static const struct net_protocol tunnelmpls4_protocol = {
233 .handler = tunnelmpls4_rcv,
234 .err_handler = tunnelmpls4_err,
235 .no_policy = 1,
236};
237#endif
238
239static int __init tunnel4_init(void)
240{
241 if (inet_add_protocol(prot: &tunnel4_protocol, IPPROTO_IPIP))
242 goto err;
243#if IS_ENABLED(CONFIG_IPV6)
244 if (inet_add_protocol(prot: &tunnel64_protocol, IPPROTO_IPV6)) {
245 inet_del_protocol(prot: &tunnel4_protocol, IPPROTO_IPIP);
246 goto err;
247 }
248#endif
249#if IS_ENABLED(CONFIG_MPLS)
250 if (inet_add_protocol(&tunnelmpls4_protocol, IPPROTO_MPLS)) {
251 inet_del_protocol(&tunnel4_protocol, IPPROTO_IPIP);
252#if IS_ENABLED(CONFIG_IPV6)
253 inet_del_protocol(&tunnel64_protocol, IPPROTO_IPV6);
254#endif
255 goto err;
256 }
257#endif
258#if IS_ENABLED(CONFIG_INET_XFRM_TUNNEL)
259 if (xfrm_input_register_afinfo(&tunnel4_input_afinfo)) {
260 inet_del_protocol(&tunnel4_protocol, IPPROTO_IPIP);
261#if IS_ENABLED(CONFIG_IPV6)
262 inet_del_protocol(&tunnel64_protocol, IPPROTO_IPV6);
263#endif
264#if IS_ENABLED(CONFIG_MPLS)
265 inet_del_protocol(&tunnelmpls4_protocol, IPPROTO_MPLS);
266#endif
267 goto err;
268 }
269#endif
270 return 0;
271
272err:
273 pr_err("%s: can't add protocol\n", __func__);
274 return -EAGAIN;
275}
276
277static void __exit tunnel4_fini(void)
278{
279#if IS_ENABLED(CONFIG_INET_XFRM_TUNNEL)
280 if (xfrm_input_unregister_afinfo(&tunnel4_input_afinfo))
281 pr_err("tunnel4 close: can't remove input afinfo\n");
282#endif
283#if IS_ENABLED(CONFIG_MPLS)
284 if (inet_del_protocol(&tunnelmpls4_protocol, IPPROTO_MPLS))
285 pr_err("tunnelmpls4 close: can't remove protocol\n");
286#endif
287#if IS_ENABLED(CONFIG_IPV6)
288 if (inet_del_protocol(prot: &tunnel64_protocol, IPPROTO_IPV6))
289 pr_err("tunnel64 close: can't remove protocol\n");
290#endif
291 if (inet_del_protocol(prot: &tunnel4_protocol, IPPROTO_IPIP))
292 pr_err("tunnel4 close: can't remove protocol\n");
293}
294
295module_init(tunnel4_init);
296module_exit(tunnel4_fini);
297MODULE_DESCRIPTION("IPv4 XFRM tunnel library");
298MODULE_LICENSE("GPL");
299