Commit | Line | Data |
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00959ade DK |
1 | /* |
2 | * GRE over IPv4 demultiplexer driver | |
3 | * | |
4 | * Authors: Dmitry Kozlov (xeb@mail.ru) | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | * | |
11 | */ | |
12 | ||
afd46503 JP |
13 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
14 | ||
00959ade | 15 | #include <linux/module.h> |
bda7bb46 PS |
16 | #include <linux/if.h> |
17 | #include <linux/icmp.h> | |
00959ade DK |
18 | #include <linux/kernel.h> |
19 | #include <linux/kmod.h> | |
20 | #include <linux/skbuff.h> | |
21 | #include <linux/in.h> | |
559fafb9 | 22 | #include <linux/ip.h> |
00959ade | 23 | #include <linux/netdevice.h> |
68c33163 | 24 | #include <linux/if_tunnel.h> |
00959ade DK |
25 | #include <linux/spinlock.h> |
26 | #include <net/protocol.h> | |
27 | #include <net/gre.h> | |
28 | ||
bda7bb46 PS |
29 | #include <net/icmp.h> |
30 | #include <net/route.h> | |
31 | #include <net/xfrm.h> | |
00959ade | 32 | |
6f0bcf15 | 33 | static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly; |
bda7bb46 | 34 | static struct gre_cisco_protocol __rcu *gre_cisco_proto_list[GRE_IP_PROTO_MAX]; |
00959ade DK |
35 | |
36 | int gre_add_protocol(const struct gre_protocol *proto, u8 version) | |
37 | { | |
38 | if (version >= GREPROTO_MAX) | |
20fd4d1f | 39 | return -EINVAL; |
00959ade | 40 | |
20fd4d1f PS |
41 | return (cmpxchg((const struct gre_protocol **)&gre_proto[version], NULL, proto) == NULL) ? |
42 | 0 : -EBUSY; | |
00959ade DK |
43 | } |
44 | EXPORT_SYMBOL_GPL(gre_add_protocol); | |
45 | ||
46 | int gre_del_protocol(const struct gre_protocol *proto, u8 version) | |
47 | { | |
20fd4d1f PS |
48 | int ret; |
49 | ||
00959ade | 50 | if (version >= GREPROTO_MAX) |
20fd4d1f PS |
51 | return -EINVAL; |
52 | ||
53 | ret = (cmpxchg((const struct gre_protocol **)&gre_proto[version], proto, NULL) == proto) ? | |
54 | 0 : -EBUSY; | |
55 | ||
56 | if (ret) | |
57 | return ret; | |
58 | ||
00959ade DK |
59 | synchronize_rcu(); |
60 | return 0; | |
00959ade DK |
61 | } |
62 | EXPORT_SYMBOL_GPL(gre_del_protocol); | |
63 | ||
752f36da PS |
64 | void gre_build_header(struct sk_buff *skb, const struct tnl_ptk_info *tpi, |
65 | int hdr_len) | |
66 | { | |
67 | struct gre_base_hdr *greh; | |
68 | ||
69 | skb_push(skb, hdr_len); | |
70 | ||
71 | greh = (struct gre_base_hdr *)skb->data; | |
72 | greh->flags = tnl_flags_to_gre_flags(tpi->flags); | |
73 | greh->protocol = tpi->proto; | |
74 | ||
75 | if (tpi->flags&(TUNNEL_KEY|TUNNEL_CSUM|TUNNEL_SEQ)) { | |
76 | __be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4); | |
77 | ||
78 | if (tpi->flags&TUNNEL_SEQ) { | |
79 | *ptr = tpi->seq; | |
80 | ptr--; | |
81 | } | |
82 | if (tpi->flags&TUNNEL_KEY) { | |
83 | *ptr = tpi->key; | |
84 | ptr--; | |
85 | } | |
86 | if (tpi->flags&TUNNEL_CSUM && | |
87 | !(skb_shinfo(skb)->gso_type & SKB_GSO_GRE)) { | |
88 | *ptr = 0; | |
89 | *(__sum16 *)ptr = csum_fold(skb_checksum(skb, 0, | |
90 | skb->len, 0)); | |
91 | } | |
92 | } | |
93 | } | |
94 | EXPORT_SYMBOL_GPL(gre_build_header); | |
95 | ||
bda7bb46 PS |
96 | static __sum16 check_checksum(struct sk_buff *skb) |
97 | { | |
98 | __sum16 csum = 0; | |
99 | ||
100 | switch (skb->ip_summed) { | |
101 | case CHECKSUM_COMPLETE: | |
102 | csum = csum_fold(skb->csum); | |
103 | ||
104 | if (!csum) | |
105 | break; | |
106 | /* Fall through. */ | |
107 | ||
108 | case CHECKSUM_NONE: | |
109 | skb->csum = 0; | |
110 | csum = __skb_checksum_complete(skb); | |
111 | skb->ip_summed = CHECKSUM_COMPLETE; | |
112 | break; | |
113 | } | |
114 | ||
115 | return csum; | |
116 | } | |
117 | ||
118 | static int parse_gre_header(struct sk_buff *skb, struct tnl_ptk_info *tpi, | |
119 | bool *csum_err) | |
120 | { | |
121 | unsigned int ip_hlen = ip_hdrlen(skb); | |
122 | const struct gre_base_hdr *greh; | |
123 | __be32 *options; | |
124 | int hdr_len; | |
125 | ||
126 | if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr)))) | |
127 | return -EINVAL; | |
128 | ||
129 | greh = (struct gre_base_hdr *)(skb_network_header(skb) + ip_hlen); | |
130 | if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING))) | |
131 | return -EINVAL; | |
132 | ||
133 | tpi->flags = gre_flags_to_tnl_flags(greh->flags); | |
134 | hdr_len = ip_gre_calc_hlen(tpi->flags); | |
135 | ||
136 | if (!pskb_may_pull(skb, hdr_len)) | |
137 | return -EINVAL; | |
138 | ||
139 | greh = (struct gre_base_hdr *)(skb_network_header(skb) + ip_hlen); | |
140 | tpi->proto = greh->protocol; | |
141 | ||
142 | options = (__be32 *)(greh + 1); | |
143 | if (greh->flags & GRE_CSUM) { | |
144 | if (check_checksum(skb)) { | |
145 | *csum_err = true; | |
146 | return -EINVAL; | |
147 | } | |
148 | options++; | |
149 | } | |
150 | ||
151 | if (greh->flags & GRE_KEY) { | |
152 | tpi->key = *options; | |
153 | options++; | |
154 | } else | |
155 | tpi->key = 0; | |
156 | ||
157 | if (unlikely(greh->flags & GRE_SEQ)) { | |
158 | tpi->seq = *options; | |
159 | options++; | |
160 | } else | |
161 | tpi->seq = 0; | |
162 | ||
163 | /* WCCP version 1 and 2 protocol decoding. | |
164 | * - Change protocol to IP | |
165 | * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header | |
166 | */ | |
167 | if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) { | |
168 | tpi->proto = htons(ETH_P_IP); | |
169 | if ((*(u8 *)options & 0xF0) != 0x40) { | |
170 | hdr_len += 4; | |
171 | if (!pskb_may_pull(skb, hdr_len)) | |
172 | return -EINVAL; | |
173 | } | |
174 | } | |
3d7b46cd PS |
175 | |
176 | return iptunnel_pull_header(skb, hdr_len, tpi->proto); | |
bda7bb46 PS |
177 | } |
178 | ||
179 | static int gre_cisco_rcv(struct sk_buff *skb) | |
180 | { | |
181 | struct tnl_ptk_info tpi; | |
182 | int i; | |
183 | bool csum_err = false; | |
184 | ||
fbd02dd4 PS |
185 | #ifdef CONFIG_NET_IPGRE_BROADCAST |
186 | if (ipv4_is_multicast(ip_hdr(skb)->daddr)) { | |
187 | /* Looped back packet, drop it! */ | |
188 | if (rt_is_output_route(skb_rtable(skb))) | |
189 | goto drop; | |
190 | } | |
191 | #endif | |
192 | ||
bda7bb46 PS |
193 | if (parse_gre_header(skb, &tpi, &csum_err) < 0) |
194 | goto drop; | |
195 | ||
196 | rcu_read_lock(); | |
197 | for (i = 0; i < GRE_IP_PROTO_MAX; i++) { | |
198 | struct gre_cisco_protocol *proto; | |
199 | int ret; | |
200 | ||
201 | proto = rcu_dereference(gre_cisco_proto_list[i]); | |
202 | if (!proto) | |
203 | continue; | |
204 | ret = proto->handler(skb, &tpi); | |
205 | if (ret == PACKET_RCVD) { | |
206 | rcu_read_unlock(); | |
207 | return 0; | |
208 | } | |
209 | } | |
210 | rcu_read_unlock(); | |
211 | ||
212 | icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0); | |
213 | drop: | |
214 | kfree_skb(skb); | |
215 | return 0; | |
216 | } | |
217 | ||
218 | static void gre_cisco_err(struct sk_buff *skb, u32 info) | |
219 | { | |
220 | /* All the routers (except for Linux) return only | |
221 | * 8 bytes of packet payload. It means, that precise relaying of | |
222 | * ICMP in the real Internet is absolutely infeasible. | |
223 | * | |
224 | * Moreover, Cisco "wise men" put GRE key to the third word | |
225 | * in GRE header. It makes impossible maintaining even soft | |
226 | * state for keyed | |
227 | * GRE tunnels with enabled checksum. Tell them "thank you". | |
228 | * | |
229 | * Well, I wonder, rfc1812 was written by Cisco employee, | |
230 | * what the hell these idiots break standards established | |
231 | * by themselves??? | |
232 | */ | |
233 | ||
234 | const int type = icmp_hdr(skb)->type; | |
235 | const int code = icmp_hdr(skb)->code; | |
236 | struct tnl_ptk_info tpi; | |
237 | bool csum_err = false; | |
238 | int i; | |
239 | ||
240 | if (parse_gre_header(skb, &tpi, &csum_err)) { | |
241 | if (!csum_err) /* ignore csum errors. */ | |
242 | return; | |
243 | } | |
244 | ||
245 | if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) { | |
246 | ipv4_update_pmtu(skb, dev_net(skb->dev), info, | |
247 | skb->dev->ifindex, 0, IPPROTO_GRE, 0); | |
248 | return; | |
249 | } | |
250 | if (type == ICMP_REDIRECT) { | |
251 | ipv4_redirect(skb, dev_net(skb->dev), skb->dev->ifindex, 0, | |
252 | IPPROTO_GRE, 0); | |
253 | return; | |
254 | } | |
255 | ||
256 | rcu_read_lock(); | |
257 | for (i = 0; i < GRE_IP_PROTO_MAX; i++) { | |
258 | struct gre_cisco_protocol *proto; | |
259 | ||
260 | proto = rcu_dereference(gre_cisco_proto_list[i]); | |
261 | if (!proto) | |
262 | continue; | |
263 | ||
264 | if (proto->err_handler(skb, info, &tpi) == PACKET_RCVD) | |
265 | goto out; | |
266 | ||
267 | } | |
268 | out: | |
269 | rcu_read_unlock(); | |
270 | } | |
271 | ||
00959ade DK |
272 | static int gre_rcv(struct sk_buff *skb) |
273 | { | |
274 | const struct gre_protocol *proto; | |
275 | u8 ver; | |
276 | int ret; | |
277 | ||
278 | if (!pskb_may_pull(skb, 12)) | |
279 | goto drop; | |
280 | ||
281 | ver = skb->data[1]&0x7f; | |
282 | if (ver >= GREPROTO_MAX) | |
283 | goto drop; | |
284 | ||
285 | rcu_read_lock(); | |
286 | proto = rcu_dereference(gre_proto[ver]); | |
287 | if (!proto || !proto->handler) | |
288 | goto drop_unlock; | |
289 | ret = proto->handler(skb); | |
290 | rcu_read_unlock(); | |
291 | return ret; | |
292 | ||
293 | drop_unlock: | |
294 | rcu_read_unlock(); | |
295 | drop: | |
296 | kfree_skb(skb); | |
297 | return NET_RX_DROP; | |
298 | } | |
299 | ||
300 | static void gre_err(struct sk_buff *skb, u32 info) | |
301 | { | |
302 | const struct gre_protocol *proto; | |
559fafb9 | 303 | const struct iphdr *iph = (const struct iphdr *)skb->data; |
304 | u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f; | |
00959ade | 305 | |
00959ade | 306 | if (ver >= GREPROTO_MAX) |
559fafb9 | 307 | return; |
00959ade DK |
308 | |
309 | rcu_read_lock(); | |
310 | proto = rcu_dereference(gre_proto[ver]); | |
559fafb9 | 311 | if (proto && proto->err_handler) |
312 | proto->err_handler(skb, info); | |
00959ade | 313 | rcu_read_unlock(); |
00959ade DK |
314 | } |
315 | ||
316 | static const struct net_protocol net_gre_protocol = { | |
317 | .handler = gre_rcv, | |
318 | .err_handler = gre_err, | |
319 | .netns_ok = 1, | |
320 | }; | |
321 | ||
bda7bb46 PS |
322 | static const struct gre_protocol ipgre_protocol = { |
323 | .handler = gre_cisco_rcv, | |
324 | .err_handler = gre_cisco_err, | |
325 | }; | |
326 | ||
327 | int gre_cisco_register(struct gre_cisco_protocol *newp) | |
328 | { | |
329 | struct gre_cisco_protocol **proto = (struct gre_cisco_protocol **) | |
330 | &gre_cisco_proto_list[newp->priority]; | |
331 | ||
332 | return (cmpxchg(proto, NULL, newp) == NULL) ? 0 : -EBUSY; | |
333 | } | |
334 | EXPORT_SYMBOL_GPL(gre_cisco_register); | |
335 | ||
336 | int gre_cisco_unregister(struct gre_cisco_protocol *del_proto) | |
337 | { | |
338 | struct gre_cisco_protocol **proto = (struct gre_cisco_protocol **) | |
339 | &gre_cisco_proto_list[del_proto->priority]; | |
340 | int ret; | |
341 | ||
342 | ret = (cmpxchg(proto, del_proto, NULL) == del_proto) ? 0 : -EINVAL; | |
343 | ||
344 | if (ret) | |
345 | return ret; | |
346 | ||
347 | synchronize_net(); | |
348 | return 0; | |
349 | } | |
350 | EXPORT_SYMBOL_GPL(gre_cisco_unregister); | |
351 | ||
00959ade DK |
352 | static int __init gre_init(void) |
353 | { | |
afd46503 | 354 | pr_info("GRE over IPv4 demultiplexor driver\n"); |
00959ade DK |
355 | |
356 | if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) { | |
afd46503 | 357 | pr_err("can't add protocol\n"); |
bda7bb46 PS |
358 | goto err; |
359 | } | |
360 | ||
361 | if (gre_add_protocol(&ipgre_protocol, GREPROTO_CISCO) < 0) { | |
362 | pr_info("%s: can't add ipgre handler\n", __func__); | |
363 | goto err_gre; | |
00959ade DK |
364 | } |
365 | ||
366 | return 0; | |
bda7bb46 PS |
367 | err_gre: |
368 | inet_del_protocol(&net_gre_protocol, IPPROTO_GRE); | |
369 | err: | |
370 | return -EAGAIN; | |
00959ade DK |
371 | } |
372 | ||
373 | static void __exit gre_exit(void) | |
374 | { | |
bda7bb46 | 375 | gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO); |
00959ade DK |
376 | inet_del_protocol(&net_gre_protocol, IPPROTO_GRE); |
377 | } | |
378 | ||
379 | module_init(gre_init); | |
380 | module_exit(gre_exit); | |
381 | ||
382 | MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver"); | |
383 | MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)"); | |
384 | MODULE_LICENSE("GPL"); |