xref: /linux/net/ipv4/xfrm4_protocol.c (revision f86fd32d) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* xfrm4_protocol.c - Generic xfrm protocol multiplexer.
3  *
4  * Copyright (C) 2013 secunet Security Networks AG
5  *
6  * Author:
7  * Steffen Klassert <steffen.klassert@secunet.com>
8  *
9  * Based on:
10  * net/ipv4/tunnel4.c
11  */
12 
13 #include <linux/init.h>
14 #include <linux/mutex.h>
15 #include <linux/skbuff.h>
16 #include <net/icmp.h>
17 #include <net/ip.h>
18 #include <net/protocol.h>
19 #include <net/xfrm.h>
20 
21 static struct xfrm4_protocol __rcu *esp4_handlers __read_mostly;
22 static struct xfrm4_protocol __rcu *ah4_handlers __read_mostly;
23 static struct xfrm4_protocol __rcu *ipcomp4_handlers __read_mostly;
24 static DEFINE_MUTEX(xfrm4_protocol_mutex);
25 
26 static inline struct xfrm4_protocol __rcu **proto_handlers(u8 protocol)
27 {
28 	switch (protocol) {
29 	case IPPROTO_ESP:
30 		return &esp4_handlers;
31 	case IPPROTO_AH:
32 		return &ah4_handlers;
33 	case IPPROTO_COMP:
34 		return &ipcomp4_handlers;
35 	}
36 
37 	return NULL;
38 }
39 
40 #define for_each_protocol_rcu(head, handler)		\
41 	for (handler = rcu_dereference(head);		\
42 	     handler != NULL;				\
43 	     handler = rcu_dereference(handler->next))	\
44 
45 static int xfrm4_rcv_cb(struct sk_buff *skb, u8 protocol, int err)
46 {
47 	int ret;
48 	struct xfrm4_protocol *handler;
49 	struct xfrm4_protocol __rcu **head = proto_handlers(protocol);
50 
51 	if (!head)
52 		return 0;
53 
54 	for_each_protocol_rcu(*head, handler)
55 		if ((ret = handler->cb_handler(skb, err)) <= 0)
56 			return ret;
57 
58 	return 0;
59 }
60 
61 int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
62 		    int encap_type)
63 {
64 	int ret;
65 	struct xfrm4_protocol *handler;
66 	struct xfrm4_protocol __rcu **head = proto_handlers(nexthdr);
67 
68 	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
69 	XFRM_SPI_SKB_CB(skb)->family = AF_INET;
70 	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
71 
72 	if (!head)
73 		goto out;
74 
75 	if (!skb_dst(skb)) {
76 		const struct iphdr *iph = ip_hdr(skb);
77 
78 		if (ip_route_input_noref(skb, iph->daddr, iph->saddr,
79 					 iph->tos, skb->dev))
80 			goto drop;
81 	}
82 
83 	for_each_protocol_rcu(*head, handler)
84 		if ((ret = handler->input_handler(skb, nexthdr, spi, encap_type)) != -EINVAL)
85 			return ret;
86 
87 out:
88 	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
89 
90 drop:
91 	kfree_skb(skb);
92 	return 0;
93 }
94 EXPORT_SYMBOL(xfrm4_rcv_encap);
95 
96 static int xfrm4_esp_rcv(struct sk_buff *skb)
97 {
98 	int ret;
99 	struct xfrm4_protocol *handler;
100 
101 	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
102 
103 	for_each_protocol_rcu(esp4_handlers, handler)
104 		if ((ret = handler->handler(skb)) != -EINVAL)
105 			return ret;
106 
107 	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
108 
109 	kfree_skb(skb);
110 	return 0;
111 }
112 
113 static int xfrm4_esp_err(struct sk_buff *skb, u32 info)
114 {
115 	struct xfrm4_protocol *handler;
116 
117 	for_each_protocol_rcu(esp4_handlers, handler)
118 		if (!handler->err_handler(skb, info))
119 			return 0;
120 
121 	return -ENOENT;
122 }
123 
124 static int xfrm4_ah_rcv(struct sk_buff *skb)
125 {
126 	int ret;
127 	struct xfrm4_protocol *handler;
128 
129 	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
130 
131 	for_each_protocol_rcu(ah4_handlers, handler)
132 		if ((ret = handler->handler(skb)) != -EINVAL)
133 			return ret;
134 
135 	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
136 
137 	kfree_skb(skb);
138 	return 0;
139 }
140 
141 static int xfrm4_ah_err(struct sk_buff *skb, u32 info)
142 {
143 	struct xfrm4_protocol *handler;
144 
145 	for_each_protocol_rcu(ah4_handlers, handler)
146 		if (!handler->err_handler(skb, info))
147 			return 0;
148 
149 	return -ENOENT;
150 }
151 
152 static int xfrm4_ipcomp_rcv(struct sk_buff *skb)
153 {
154 	int ret;
155 	struct xfrm4_protocol *handler;
156 
157 	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
158 
159 	for_each_protocol_rcu(ipcomp4_handlers, handler)
160 		if ((ret = handler->handler(skb)) != -EINVAL)
161 			return ret;
162 
163 	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
164 
165 	kfree_skb(skb);
166 	return 0;
167 }
168 
169 static int xfrm4_ipcomp_err(struct sk_buff *skb, u32 info)
170 {
171 	struct xfrm4_protocol *handler;
172 
173 	for_each_protocol_rcu(ipcomp4_handlers, handler)
174 		if (!handler->err_handler(skb, info))
175 			return 0;
176 
177 	return -ENOENT;
178 }
179 
180 static const struct net_protocol esp4_protocol = {
181 	.handler	=	xfrm4_esp_rcv,
182 	.err_handler	=	xfrm4_esp_err,
183 	.no_policy	=	1,
184 	.netns_ok	=	1,
185 };
186 
187 static const struct net_protocol ah4_protocol = {
188 	.handler	=	xfrm4_ah_rcv,
189 	.err_handler	=	xfrm4_ah_err,
190 	.no_policy	=	1,
191 	.netns_ok	=	1,
192 };
193 
194 static const struct net_protocol ipcomp4_protocol = {
195 	.handler	=	xfrm4_ipcomp_rcv,
196 	.err_handler	=	xfrm4_ipcomp_err,
197 	.no_policy	=	1,
198 	.netns_ok	=	1,
199 };
200 
201 static const struct xfrm_input_afinfo xfrm4_input_afinfo = {
202 	.family		=	AF_INET,
203 	.callback	=	xfrm4_rcv_cb,
204 };
205 
206 static inline const struct net_protocol *netproto(unsigned char protocol)
207 {
208 	switch (protocol) {
209 	case IPPROTO_ESP:
210 		return &esp4_protocol;
211 	case IPPROTO_AH:
212 		return &ah4_protocol;
213 	case IPPROTO_COMP:
214 		return &ipcomp4_protocol;
215 	}
216 
217 	return NULL;
218 }
219 
220 int xfrm4_protocol_register(struct xfrm4_protocol *handler,
221 			    unsigned char protocol)
222 {
223 	struct xfrm4_protocol __rcu **pprev;
224 	struct xfrm4_protocol *t;
225 	bool add_netproto = false;
226 	int ret = -EEXIST;
227 	int priority = handler->priority;
228 
229 	if (!proto_handlers(protocol) || !netproto(protocol))
230 		return -EINVAL;
231 
232 	mutex_lock(&xfrm4_protocol_mutex);
233 
234 	if (!rcu_dereference_protected(*proto_handlers(protocol),
235 				       lockdep_is_held(&xfrm4_protocol_mutex)))
236 		add_netproto = true;
237 
238 	for (pprev = proto_handlers(protocol);
239 	     (t = rcu_dereference_protected(*pprev,
240 			lockdep_is_held(&xfrm4_protocol_mutex))) != NULL;
241 	     pprev = &t->next) {
242 		if (t->priority < priority)
243 			break;
244 		if (t->priority == priority)
245 			goto err;
246 	}
247 
248 	handler->next = *pprev;
249 	rcu_assign_pointer(*pprev, handler);
250 
251 	ret = 0;
252 
253 err:
254 	mutex_unlock(&xfrm4_protocol_mutex);
255 
256 	if (add_netproto) {
257 		if (inet_add_protocol(netproto(protocol), protocol)) {
258 			pr_err("%s: can't add protocol\n", __func__);
259 			ret = -EAGAIN;
260 		}
261 	}
262 
263 	return ret;
264 }
265 EXPORT_SYMBOL(xfrm4_protocol_register);
266 
267 int xfrm4_protocol_deregister(struct xfrm4_protocol *handler,
268 			      unsigned char protocol)
269 {
270 	struct xfrm4_protocol __rcu **pprev;
271 	struct xfrm4_protocol *t;
272 	int ret = -ENOENT;
273 
274 	if (!proto_handlers(protocol) || !netproto(protocol))
275 		return -EINVAL;
276 
277 	mutex_lock(&xfrm4_protocol_mutex);
278 
279 	for (pprev = proto_handlers(protocol);
280 	     (t = rcu_dereference_protected(*pprev,
281 			lockdep_is_held(&xfrm4_protocol_mutex))) != NULL;
282 	     pprev = &t->next) {
283 		if (t == handler) {
284 			*pprev = handler->next;
285 			ret = 0;
286 			break;
287 		}
288 	}
289 
290 	if (!rcu_dereference_protected(*proto_handlers(protocol),
291 				       lockdep_is_held(&xfrm4_protocol_mutex))) {
292 		if (inet_del_protocol(netproto(protocol), protocol) < 0) {
293 			pr_err("%s: can't remove protocol\n", __func__);
294 			ret = -EAGAIN;
295 		}
296 	}
297 
298 	mutex_unlock(&xfrm4_protocol_mutex);
299 
300 	synchronize_net();
301 
302 	return ret;
303 }
304 EXPORT_SYMBOL(xfrm4_protocol_deregister);
305 
306 void __init xfrm4_protocol_init(void)
307 {
308 	xfrm_input_register_afinfo(&xfrm4_input_afinfo);
309 }
310 EXPORT_SYMBOL(xfrm4_protocol_init);
311