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(&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(&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(&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}
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, 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
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, 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
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(&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
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(&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
295module_init(tunnel4_init);
296module_exit(tunnel4_fini);
297MODULE_DESCRIPTION("IPv4 XFRM tunnel library");
298MODULE_LICENSE("GPL");
299