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 | ||
45f2e997 PS |
96 | struct sk_buff *gre_handle_offloads(struct sk_buff *skb, bool gre_csum) |
97 | { | |
98 | int err; | |
99 | ||
100 | if (likely(!skb->encapsulation)) { | |
101 | skb_reset_inner_headers(skb); | |
102 | skb->encapsulation = 1; | |
103 | } | |
104 | ||
105 | if (skb_is_gso(skb)) { | |
106 | err = skb_unclone(skb, GFP_ATOMIC); | |
107 | if (unlikely(err)) | |
108 | goto error; | |
109 | skb_shinfo(skb)->gso_type |= SKB_GSO_GRE; | |
110 | return skb; | |
111 | } else if (skb->ip_summed == CHECKSUM_PARTIAL && gre_csum) { | |
112 | err = skb_checksum_help(skb); | |
113 | if (unlikely(err)) | |
114 | goto error; | |
115 | } else if (skb->ip_summed != CHECKSUM_PARTIAL) | |
116 | skb->ip_summed = CHECKSUM_NONE; | |
117 | ||
118 | return skb; | |
119 | error: | |
120 | kfree_skb(skb); | |
121 | return ERR_PTR(err); | |
122 | } | |
123 | EXPORT_SYMBOL_GPL(gre_handle_offloads); | |
124 | ||
bda7bb46 PS |
125 | static __sum16 check_checksum(struct sk_buff *skb) |
126 | { | |
127 | __sum16 csum = 0; | |
128 | ||
129 | switch (skb->ip_summed) { | |
130 | case CHECKSUM_COMPLETE: | |
131 | csum = csum_fold(skb->csum); | |
132 | ||
133 | if (!csum) | |
134 | break; | |
135 | /* Fall through. */ | |
136 | ||
137 | case CHECKSUM_NONE: | |
138 | skb->csum = 0; | |
139 | csum = __skb_checksum_complete(skb); | |
140 | skb->ip_summed = CHECKSUM_COMPLETE; | |
141 | break; | |
142 | } | |
143 | ||
144 | return csum; | |
145 | } | |
146 | ||
147 | static int parse_gre_header(struct sk_buff *skb, struct tnl_ptk_info *tpi, | |
148 | bool *csum_err) | |
149 | { | |
150 | unsigned int ip_hlen = ip_hdrlen(skb); | |
151 | const struct gre_base_hdr *greh; | |
152 | __be32 *options; | |
153 | int hdr_len; | |
154 | ||
155 | if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr)))) | |
156 | return -EINVAL; | |
157 | ||
158 | greh = (struct gre_base_hdr *)(skb_network_header(skb) + ip_hlen); | |
159 | if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING))) | |
160 | return -EINVAL; | |
161 | ||
162 | tpi->flags = gre_flags_to_tnl_flags(greh->flags); | |
163 | hdr_len = ip_gre_calc_hlen(tpi->flags); | |
164 | ||
165 | if (!pskb_may_pull(skb, hdr_len)) | |
166 | return -EINVAL; | |
167 | ||
168 | greh = (struct gre_base_hdr *)(skb_network_header(skb) + ip_hlen); | |
169 | tpi->proto = greh->protocol; | |
170 | ||
171 | options = (__be32 *)(greh + 1); | |
172 | if (greh->flags & GRE_CSUM) { | |
173 | if (check_checksum(skb)) { | |
174 | *csum_err = true; | |
175 | return -EINVAL; | |
176 | } | |
177 | options++; | |
178 | } | |
179 | ||
180 | if (greh->flags & GRE_KEY) { | |
181 | tpi->key = *options; | |
182 | options++; | |
183 | } else | |
184 | tpi->key = 0; | |
185 | ||
186 | if (unlikely(greh->flags & GRE_SEQ)) { | |
187 | tpi->seq = *options; | |
188 | options++; | |
189 | } else | |
190 | tpi->seq = 0; | |
191 | ||
192 | /* WCCP version 1 and 2 protocol decoding. | |
193 | * - Change protocol to IP | |
194 | * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header | |
195 | */ | |
196 | if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) { | |
197 | tpi->proto = htons(ETH_P_IP); | |
198 | if ((*(u8 *)options & 0xF0) != 0x40) { | |
199 | hdr_len += 4; | |
200 | if (!pskb_may_pull(skb, hdr_len)) | |
201 | return -EINVAL; | |
202 | } | |
203 | } | |
3d7b46cd PS |
204 | |
205 | return iptunnel_pull_header(skb, hdr_len, tpi->proto); | |
bda7bb46 PS |
206 | } |
207 | ||
208 | static int gre_cisco_rcv(struct sk_buff *skb) | |
209 | { | |
210 | struct tnl_ptk_info tpi; | |
211 | int i; | |
212 | bool csum_err = false; | |
213 | ||
214 | if (parse_gre_header(skb, &tpi, &csum_err) < 0) | |
215 | goto drop; | |
216 | ||
217 | rcu_read_lock(); | |
218 | for (i = 0; i < GRE_IP_PROTO_MAX; i++) { | |
219 | struct gre_cisco_protocol *proto; | |
220 | int ret; | |
221 | ||
222 | proto = rcu_dereference(gre_cisco_proto_list[i]); | |
223 | if (!proto) | |
224 | continue; | |
225 | ret = proto->handler(skb, &tpi); | |
226 | if (ret == PACKET_RCVD) { | |
227 | rcu_read_unlock(); | |
228 | return 0; | |
229 | } | |
230 | } | |
231 | rcu_read_unlock(); | |
232 | ||
233 | icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0); | |
234 | drop: | |
235 | kfree_skb(skb); | |
236 | return 0; | |
237 | } | |
238 | ||
239 | static void gre_cisco_err(struct sk_buff *skb, u32 info) | |
240 | { | |
241 | /* All the routers (except for Linux) return only | |
242 | * 8 bytes of packet payload. It means, that precise relaying of | |
243 | * ICMP in the real Internet is absolutely infeasible. | |
244 | * | |
245 | * Moreover, Cisco "wise men" put GRE key to the third word | |
246 | * in GRE header. It makes impossible maintaining even soft | |
247 | * state for keyed | |
248 | * GRE tunnels with enabled checksum. Tell them "thank you". | |
249 | * | |
250 | * Well, I wonder, rfc1812 was written by Cisco employee, | |
251 | * what the hell these idiots break standards established | |
252 | * by themselves??? | |
253 | */ | |
254 | ||
255 | const int type = icmp_hdr(skb)->type; | |
256 | const int code = icmp_hdr(skb)->code; | |
257 | struct tnl_ptk_info tpi; | |
258 | bool csum_err = false; | |
259 | int i; | |
260 | ||
261 | if (parse_gre_header(skb, &tpi, &csum_err)) { | |
262 | if (!csum_err) /* ignore csum errors. */ | |
263 | return; | |
264 | } | |
265 | ||
266 | if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) { | |
267 | ipv4_update_pmtu(skb, dev_net(skb->dev), info, | |
268 | skb->dev->ifindex, 0, IPPROTO_GRE, 0); | |
269 | return; | |
270 | } | |
271 | if (type == ICMP_REDIRECT) { | |
272 | ipv4_redirect(skb, dev_net(skb->dev), skb->dev->ifindex, 0, | |
273 | IPPROTO_GRE, 0); | |
274 | return; | |
275 | } | |
276 | ||
277 | rcu_read_lock(); | |
278 | for (i = 0; i < GRE_IP_PROTO_MAX; i++) { | |
279 | struct gre_cisco_protocol *proto; | |
280 | ||
281 | proto = rcu_dereference(gre_cisco_proto_list[i]); | |
282 | if (!proto) | |
283 | continue; | |
284 | ||
285 | if (proto->err_handler(skb, info, &tpi) == PACKET_RCVD) | |
286 | goto out; | |
287 | ||
288 | } | |
289 | out: | |
290 | rcu_read_unlock(); | |
291 | } | |
292 | ||
00959ade DK |
293 | static int gre_rcv(struct sk_buff *skb) |
294 | { | |
295 | const struct gre_protocol *proto; | |
296 | u8 ver; | |
297 | int ret; | |
298 | ||
299 | if (!pskb_may_pull(skb, 12)) | |
300 | goto drop; | |
301 | ||
302 | ver = skb->data[1]&0x7f; | |
303 | if (ver >= GREPROTO_MAX) | |
304 | goto drop; | |
305 | ||
306 | rcu_read_lock(); | |
307 | proto = rcu_dereference(gre_proto[ver]); | |
308 | if (!proto || !proto->handler) | |
309 | goto drop_unlock; | |
310 | ret = proto->handler(skb); | |
311 | rcu_read_unlock(); | |
312 | return ret; | |
313 | ||
314 | drop_unlock: | |
315 | rcu_read_unlock(); | |
316 | drop: | |
317 | kfree_skb(skb); | |
318 | return NET_RX_DROP; | |
319 | } | |
320 | ||
321 | static void gre_err(struct sk_buff *skb, u32 info) | |
322 | { | |
323 | const struct gre_protocol *proto; | |
559fafb9 | 324 | const struct iphdr *iph = (const struct iphdr *)skb->data; |
325 | u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f; | |
00959ade | 326 | |
00959ade | 327 | if (ver >= GREPROTO_MAX) |
559fafb9 | 328 | return; |
00959ade DK |
329 | |
330 | rcu_read_lock(); | |
331 | proto = rcu_dereference(gre_proto[ver]); | |
559fafb9 | 332 | if (proto && proto->err_handler) |
333 | proto->err_handler(skb, info); | |
00959ade | 334 | rcu_read_unlock(); |
00959ade DK |
335 | } |
336 | ||
337 | static const struct net_protocol net_gre_protocol = { | |
338 | .handler = gre_rcv, | |
339 | .err_handler = gre_err, | |
340 | .netns_ok = 1, | |
341 | }; | |
342 | ||
bda7bb46 PS |
343 | static const struct gre_protocol ipgre_protocol = { |
344 | .handler = gre_cisco_rcv, | |
345 | .err_handler = gre_cisco_err, | |
346 | }; | |
347 | ||
348 | int gre_cisco_register(struct gre_cisco_protocol *newp) | |
349 | { | |
350 | struct gre_cisco_protocol **proto = (struct gre_cisco_protocol **) | |
351 | &gre_cisco_proto_list[newp->priority]; | |
352 | ||
353 | return (cmpxchg(proto, NULL, newp) == NULL) ? 0 : -EBUSY; | |
354 | } | |
355 | EXPORT_SYMBOL_GPL(gre_cisco_register); | |
356 | ||
357 | int gre_cisco_unregister(struct gre_cisco_protocol *del_proto) | |
358 | { | |
359 | struct gre_cisco_protocol **proto = (struct gre_cisco_protocol **) | |
360 | &gre_cisco_proto_list[del_proto->priority]; | |
361 | int ret; | |
362 | ||
363 | ret = (cmpxchg(proto, del_proto, NULL) == del_proto) ? 0 : -EINVAL; | |
364 | ||
365 | if (ret) | |
366 | return ret; | |
367 | ||
368 | synchronize_net(); | |
369 | return 0; | |
370 | } | |
371 | EXPORT_SYMBOL_GPL(gre_cisco_unregister); | |
372 | ||
00959ade DK |
373 | static int __init gre_init(void) |
374 | { | |
afd46503 | 375 | pr_info("GRE over IPv4 demultiplexor driver\n"); |
00959ade DK |
376 | |
377 | if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) { | |
afd46503 | 378 | pr_err("can't add protocol\n"); |
bda7bb46 PS |
379 | goto err; |
380 | } | |
381 | ||
382 | if (gre_add_protocol(&ipgre_protocol, GREPROTO_CISCO) < 0) { | |
383 | pr_info("%s: can't add ipgre handler\n", __func__); | |
384 | goto err_gre; | |
00959ade DK |
385 | } |
386 | ||
c50cd357 | 387 | if (gre_offload_init()) { |
68c33163 | 388 | pr_err("can't add protocol offload\n"); |
bda7bb46 | 389 | goto err_gso; |
68c33163 PS |
390 | } |
391 | ||
00959ade | 392 | return 0; |
bda7bb46 PS |
393 | err_gso: |
394 | gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO); | |
395 | err_gre: | |
396 | inet_del_protocol(&net_gre_protocol, IPPROTO_GRE); | |
397 | err: | |
398 | return -EAGAIN; | |
00959ade DK |
399 | } |
400 | ||
401 | static void __exit gre_exit(void) | |
402 | { | |
c50cd357 DB |
403 | gre_offload_exit(); |
404 | ||
bda7bb46 | 405 | gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO); |
00959ade DK |
406 | inet_del_protocol(&net_gre_protocol, IPPROTO_GRE); |
407 | } | |
408 | ||
409 | module_init(gre_init); | |
410 | module_exit(gre_exit); | |
411 | ||
412 | MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver"); | |
413 | MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)"); | |
414 | MODULE_LICENSE("GPL"); |