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 
19 static struct xfrm_tunnel __rcu *tunnel4_handlers __read_mostly;
20 static struct xfrm_tunnel __rcu *tunnel64_handlers __read_mostly;
21 static struct xfrm_tunnel __rcu *tunnelmpls4_handlers __read_mostly;
22 static DEFINE_MUTEX(tunnel4_mutex);
23 
fam_handlers(unsigned short family)24 static 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 
xfrm4_tunnel_register(struct xfrm_tunnel * handler,unsigned short family)31 int 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(&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 
56 err:
57 	mutex_unlock(&tunnel4_mutex);
58 
59 	return ret;
60 }
61 EXPORT_SYMBOL(xfrm4_tunnel_register);
62 
xfrm4_tunnel_deregister(struct xfrm_tunnel * handler,unsigned short family)63 int 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(&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(&tunnel4_mutex);
83 
84 	synchronize_net();
85 
86 	return ret;
87 }
88 EXPORT_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 
tunnel4_rcv(struct sk_buff * skb)95 static int tunnel4_rcv(struct sk_buff *skb)
96 {
97 	struct xfrm_tunnel *handler;
98 
99 	if (!pskb_may_pull(skb, 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, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
107 
108 drop:
109 	kfree_skb(skb);
110 	return 0;
111 }
112 
113 #if IS_ENABLED(CONFIG_INET_XFRM_TUNNEL)
tunnel4_rcv_cb(struct sk_buff * skb,u8 proto,int err)114 static 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 
133 static 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)
tunnel64_rcv(struct sk_buff * skb)141 static int tunnel64_rcv(struct sk_buff *skb)
142 {
143 	struct xfrm_tunnel *handler;
144 
145 	if (!pskb_may_pull(skb, 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, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
153 
154 drop:
155 	kfree_skb(skb);
156 	return 0;
157 }
158 #endif
159 
160 #if IS_ENABLED(CONFIG_MPLS)
tunnelmpls4_rcv(struct sk_buff * skb)161 static 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 
174 drop:
175 	kfree_skb(skb);
176 	return 0;
177 }
178 #endif
179 
tunnel4_err(struct sk_buff * skb,u32 info)180 static 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)
tunnel64_err(struct sk_buff * skb,u32 info)192 static 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)
tunnelmpls4_err(struct sk_buff * skb,u32 info)205 static 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 
217 static 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)
224 static 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)
232 static const struct net_protocol tunnelmpls4_protocol = {
233 	.handler	=	tunnelmpls4_rcv,
234 	.err_handler	=	tunnelmpls4_err,
235 	.no_policy	=	1,
236 };
237 #endif
238 
tunnel4_init(void)239 static int __init tunnel4_init(void)
240 {
241 	if (inet_add_protocol(&tunnel4_protocol, IPPROTO_IPIP))
242 		goto err;
243 #if IS_ENABLED(CONFIG_IPV6)
244 	if (inet_add_protocol(&tunnel64_protocol, IPPROTO_IPV6)) {
245 		inet_del_protocol(&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 
272 err:
273 	pr_err("%s: can't add protocol\n", __func__);
274 	return -EAGAIN;
275 }
276 
tunnel4_fini(void)277 static 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(&tunnel64_protocol, IPPROTO_IPV6))
289 		pr_err("tunnel64 close: can't remove protocol\n");
290 #endif
291 	if (inet_del_protocol(&tunnel4_protocol, IPPROTO_IPIP))
292 		pr_err("tunnel4 close: can't remove protocol\n");
293 }
294 
295 module_init(tunnel4_init);
296 module_exit(tunnel4_fini);
297 MODULE_LICENSE("GPL");
298