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 };
185
186 static const struct net_protocol ah4_protocol = {
187 .handler = xfrm4_ah_rcv,
188 .err_handler = xfrm4_ah_err,
189 .no_policy = 1,
190 };
191
192 static const struct net_protocol ipcomp4_protocol = {
193 .handler = xfrm4_ipcomp_rcv,
194 .err_handler = xfrm4_ipcomp_err,
195 .no_policy = 1,
196 };
197
198 static const struct xfrm_input_afinfo xfrm4_input_afinfo = {
199 .family = AF_INET,
200 .callback = xfrm4_rcv_cb,
201 };
202
203 static inline const struct net_protocol *netproto(unsigned char protocol)
204 {
205 switch (protocol) {
206 case IPPROTO_ESP:
207 return &esp4_protocol;
208 case IPPROTO_AH:
209 return &ah4_protocol;
210 case IPPROTO_COMP:
211 return &ipcomp4_protocol;
212 }
213
214 return NULL;
215 }
216
217 int xfrm4_protocol_register(struct xfrm4_protocol *handler,
218 unsigned char protocol)
219 {
220 struct xfrm4_protocol __rcu **pprev;
221 struct xfrm4_protocol *t;
222 bool add_netproto = false;
223 int ret = -EEXIST;
224 int priority = handler->priority;
225
226 if (!proto_handlers(protocol) || !netproto(protocol))
227 return -EINVAL;
228
229 mutex_lock(&xfrm4_protocol_mutex);
230
231 if (!rcu_dereference_protected(*proto_handlers(protocol),
232 lockdep_is_held(&xfrm4_protocol_mutex)))
233 add_netproto = true;
234
235 for (pprev = proto_handlers(protocol);
236 (t = rcu_dereference_protected(*pprev,
237 lockdep_is_held(&xfrm4_protocol_mutex))) != NULL;
238 pprev = &t->next) {
239 if (t->priority < priority)
240 break;
241 if (t->priority == priority)
242 goto err;
243 }
244
245 handler->next = *pprev;
246 rcu_assign_pointer(*pprev, handler);
247
248 ret = 0;
249
250 err:
251 mutex_unlock(&xfrm4_protocol_mutex);
252
253 if (add_netproto) {
254 if (inet_add_protocol(netproto(protocol), protocol)) {
255 pr_err("%s: can't add protocol\n", __func__);
256 ret = -EAGAIN;
257 }
258 }
259
260 return ret;
261 }
262 EXPORT_SYMBOL(xfrm4_protocol_register);
263
264 int xfrm4_protocol_deregister(struct xfrm4_protocol *handler,
265 unsigned char protocol)
266 {
267 struct xfrm4_protocol __rcu **pprev;
268 struct xfrm4_protocol *t;
269 int ret = -ENOENT;
270
271 if (!proto_handlers(protocol) || !netproto(protocol))
272 return -EINVAL;
273
274 mutex_lock(&xfrm4_protocol_mutex);
275
276 for (pprev = proto_handlers(protocol);
277 (t = rcu_dereference_protected(*pprev,
278 lockdep_is_held(&xfrm4_protocol_mutex))) != NULL;
279 pprev = &t->next) {
280 if (t == handler) {
281 *pprev = handler->next;
282 ret = 0;
283 break;
284 }
285 }
286
287 if (!rcu_dereference_protected(*proto_handlers(protocol),
288 lockdep_is_held(&xfrm4_protocol_mutex))) {
289 if (inet_del_protocol(netproto(protocol), protocol) < 0) {
290 pr_err("%s: can't remove protocol\n", __func__);
291 ret = -EAGAIN;
292 }
293 }
294
295 mutex_unlock(&xfrm4_protocol_mutex);
296
297 synchronize_net();
298
299 return ret;
300 }
301 EXPORT_SYMBOL(xfrm4_protocol_deregister);
302
303 void __init xfrm4_protocol_init(void)
304 {
305 xfrm_input_register_afinfo(&xfrm4_input_afinfo);
306 }
307
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