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 | ||
d0a7ebbc | 71 | skb_reset_transport_header(skb); |
752f36da PS |
72 | greh = (struct gre_base_hdr *)skb->data; |
73 | greh->flags = tnl_flags_to_gre_flags(tpi->flags); | |
74 | greh->protocol = tpi->proto; | |
75 | ||
76 | if (tpi->flags&(TUNNEL_KEY|TUNNEL_CSUM|TUNNEL_SEQ)) { | |
77 | __be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4); | |
78 | ||
79 | if (tpi->flags&TUNNEL_SEQ) { | |
80 | *ptr = tpi->seq; | |
81 | ptr--; | |
82 | } | |
83 | if (tpi->flags&TUNNEL_KEY) { | |
84 | *ptr = tpi->key; | |
85 | ptr--; | |
86 | } | |
87 | if (tpi->flags&TUNNEL_CSUM && | |
4749c09c TH |
88 | !(skb_shinfo(skb)->gso_type & |
89 | (SKB_GSO_GRE|SKB_GSO_GRE_CSUM))) { | |
752f36da PS |
90 | *ptr = 0; |
91 | *(__sum16 *)ptr = csum_fold(skb_checksum(skb, 0, | |
92 | skb->len, 0)); | |
93 | } | |
94 | } | |
95 | } | |
96 | EXPORT_SYMBOL_GPL(gre_build_header); | |
97 | ||
bda7bb46 PS |
98 | static int parse_gre_header(struct sk_buff *skb, struct tnl_ptk_info *tpi, |
99 | bool *csum_err) | |
100 | { | |
101 | unsigned int ip_hlen = ip_hdrlen(skb); | |
102 | const struct gre_base_hdr *greh; | |
103 | __be32 *options; | |
104 | int hdr_len; | |
105 | ||
106 | if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr)))) | |
107 | return -EINVAL; | |
108 | ||
109 | greh = (struct gre_base_hdr *)(skb_network_header(skb) + ip_hlen); | |
110 | if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING))) | |
111 | return -EINVAL; | |
112 | ||
113 | tpi->flags = gre_flags_to_tnl_flags(greh->flags); | |
114 | hdr_len = ip_gre_calc_hlen(tpi->flags); | |
115 | ||
116 | if (!pskb_may_pull(skb, hdr_len)) | |
117 | return -EINVAL; | |
118 | ||
119 | greh = (struct gre_base_hdr *)(skb_network_header(skb) + ip_hlen); | |
120 | tpi->proto = greh->protocol; | |
121 | ||
122 | options = (__be32 *)(greh + 1); | |
123 | if (greh->flags & GRE_CSUM) { | |
b1036c6a | 124 | if (skb_checksum_simple_validate(skb)) { |
bda7bb46 PS |
125 | *csum_err = true; |
126 | return -EINVAL; | |
127 | } | |
128 | options++; | |
129 | } | |
130 | ||
131 | if (greh->flags & GRE_KEY) { | |
132 | tpi->key = *options; | |
133 | options++; | |
134 | } else | |
135 | tpi->key = 0; | |
136 | ||
137 | if (unlikely(greh->flags & GRE_SEQ)) { | |
138 | tpi->seq = *options; | |
139 | options++; | |
140 | } else | |
141 | tpi->seq = 0; | |
142 | ||
143 | /* WCCP version 1 and 2 protocol decoding. | |
144 | * - Change protocol to IP | |
145 | * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header | |
146 | */ | |
147 | if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) { | |
148 | tpi->proto = htons(ETH_P_IP); | |
149 | if ((*(u8 *)options & 0xF0) != 0x40) { | |
150 | hdr_len += 4; | |
151 | if (!pskb_may_pull(skb, hdr_len)) | |
152 | return -EINVAL; | |
153 | } | |
154 | } | |
3d7b46cd PS |
155 | |
156 | return iptunnel_pull_header(skb, hdr_len, tpi->proto); | |
bda7bb46 PS |
157 | } |
158 | ||
159 | static int gre_cisco_rcv(struct sk_buff *skb) | |
160 | { | |
161 | struct tnl_ptk_info tpi; | |
162 | int i; | |
163 | bool csum_err = false; | |
164 | ||
fbd02dd4 PS |
165 | #ifdef CONFIG_NET_IPGRE_BROADCAST |
166 | if (ipv4_is_multicast(ip_hdr(skb)->daddr)) { | |
167 | /* Looped back packet, drop it! */ | |
168 | if (rt_is_output_route(skb_rtable(skb))) | |
169 | goto drop; | |
170 | } | |
171 | #endif | |
172 | ||
bda7bb46 PS |
173 | if (parse_gre_header(skb, &tpi, &csum_err) < 0) |
174 | goto drop; | |
175 | ||
176 | rcu_read_lock(); | |
177 | for (i = 0; i < GRE_IP_PROTO_MAX; i++) { | |
178 | struct gre_cisco_protocol *proto; | |
179 | int ret; | |
180 | ||
181 | proto = rcu_dereference(gre_cisco_proto_list[i]); | |
182 | if (!proto) | |
183 | continue; | |
184 | ret = proto->handler(skb, &tpi); | |
185 | if (ret == PACKET_RCVD) { | |
186 | rcu_read_unlock(); | |
187 | return 0; | |
188 | } | |
189 | } | |
190 | rcu_read_unlock(); | |
191 | ||
192 | icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0); | |
193 | drop: | |
194 | kfree_skb(skb); | |
195 | return 0; | |
196 | } | |
197 | ||
198 | static void gre_cisco_err(struct sk_buff *skb, u32 info) | |
199 | { | |
200 | /* All the routers (except for Linux) return only | |
201 | * 8 bytes of packet payload. It means, that precise relaying of | |
202 | * ICMP in the real Internet is absolutely infeasible. | |
203 | * | |
204 | * Moreover, Cisco "wise men" put GRE key to the third word | |
205 | * in GRE header. It makes impossible maintaining even soft | |
206 | * state for keyed | |
207 | * GRE tunnels with enabled checksum. Tell them "thank you". | |
208 | * | |
209 | * Well, I wonder, rfc1812 was written by Cisco employee, | |
210 | * what the hell these idiots break standards established | |
211 | * by themselves??? | |
212 | */ | |
213 | ||
214 | const int type = icmp_hdr(skb)->type; | |
215 | const int code = icmp_hdr(skb)->code; | |
216 | struct tnl_ptk_info tpi; | |
217 | bool csum_err = false; | |
218 | int i; | |
219 | ||
220 | if (parse_gre_header(skb, &tpi, &csum_err)) { | |
221 | if (!csum_err) /* ignore csum errors. */ | |
222 | return; | |
223 | } | |
224 | ||
225 | if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) { | |
226 | ipv4_update_pmtu(skb, dev_net(skb->dev), info, | |
227 | skb->dev->ifindex, 0, IPPROTO_GRE, 0); | |
228 | return; | |
229 | } | |
230 | if (type == ICMP_REDIRECT) { | |
231 | ipv4_redirect(skb, dev_net(skb->dev), skb->dev->ifindex, 0, | |
232 | IPPROTO_GRE, 0); | |
233 | return; | |
234 | } | |
235 | ||
236 | rcu_read_lock(); | |
237 | for (i = 0; i < GRE_IP_PROTO_MAX; i++) { | |
238 | struct gre_cisco_protocol *proto; | |
239 | ||
240 | proto = rcu_dereference(gre_cisco_proto_list[i]); | |
241 | if (!proto) | |
242 | continue; | |
243 | ||
244 | if (proto->err_handler(skb, info, &tpi) == PACKET_RCVD) | |
245 | goto out; | |
246 | ||
247 | } | |
248 | out: | |
249 | rcu_read_unlock(); | |
250 | } | |
251 | ||
00959ade DK |
252 | static int gre_rcv(struct sk_buff *skb) |
253 | { | |
254 | const struct gre_protocol *proto; | |
255 | u8 ver; | |
256 | int ret; | |
257 | ||
258 | if (!pskb_may_pull(skb, 12)) | |
259 | goto drop; | |
260 | ||
261 | ver = skb->data[1]&0x7f; | |
262 | if (ver >= GREPROTO_MAX) | |
263 | goto drop; | |
264 | ||
265 | rcu_read_lock(); | |
266 | proto = rcu_dereference(gre_proto[ver]); | |
267 | if (!proto || !proto->handler) | |
268 | goto drop_unlock; | |
269 | ret = proto->handler(skb); | |
270 | rcu_read_unlock(); | |
271 | return ret; | |
272 | ||
273 | drop_unlock: | |
274 | rcu_read_unlock(); | |
275 | drop: | |
276 | kfree_skb(skb); | |
277 | return NET_RX_DROP; | |
278 | } | |
279 | ||
280 | static void gre_err(struct sk_buff *skb, u32 info) | |
281 | { | |
282 | const struct gre_protocol *proto; | |
559fafb9 | 283 | const struct iphdr *iph = (const struct iphdr *)skb->data; |
284 | u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f; | |
00959ade | 285 | |
00959ade | 286 | if (ver >= GREPROTO_MAX) |
559fafb9 | 287 | return; |
00959ade DK |
288 | |
289 | rcu_read_lock(); | |
290 | proto = rcu_dereference(gre_proto[ver]); | |
559fafb9 | 291 | if (proto && proto->err_handler) |
292 | proto->err_handler(skb, info); | |
00959ade | 293 | rcu_read_unlock(); |
00959ade DK |
294 | } |
295 | ||
296 | static const struct net_protocol net_gre_protocol = { | |
297 | .handler = gre_rcv, | |
298 | .err_handler = gre_err, | |
299 | .netns_ok = 1, | |
300 | }; | |
301 | ||
bda7bb46 PS |
302 | static const struct gre_protocol ipgre_protocol = { |
303 | .handler = gre_cisco_rcv, | |
304 | .err_handler = gre_cisco_err, | |
305 | }; | |
306 | ||
307 | int gre_cisco_register(struct gre_cisco_protocol *newp) | |
308 | { | |
309 | struct gre_cisco_protocol **proto = (struct gre_cisco_protocol **) | |
310 | &gre_cisco_proto_list[newp->priority]; | |
311 | ||
312 | return (cmpxchg(proto, NULL, newp) == NULL) ? 0 : -EBUSY; | |
313 | } | |
314 | EXPORT_SYMBOL_GPL(gre_cisco_register); | |
315 | ||
316 | int gre_cisco_unregister(struct gre_cisco_protocol *del_proto) | |
317 | { | |
318 | struct gre_cisco_protocol **proto = (struct gre_cisco_protocol **) | |
319 | &gre_cisco_proto_list[del_proto->priority]; | |
320 | int ret; | |
321 | ||
322 | ret = (cmpxchg(proto, del_proto, NULL) == del_proto) ? 0 : -EINVAL; | |
323 | ||
324 | if (ret) | |
325 | return ret; | |
326 | ||
327 | synchronize_net(); | |
328 | return 0; | |
329 | } | |
330 | EXPORT_SYMBOL_GPL(gre_cisco_unregister); | |
331 | ||
00959ade DK |
332 | static int __init gre_init(void) |
333 | { | |
afd46503 | 334 | pr_info("GRE over IPv4 demultiplexor driver\n"); |
00959ade DK |
335 | |
336 | if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) { | |
afd46503 | 337 | pr_err("can't add protocol\n"); |
bda7bb46 PS |
338 | goto err; |
339 | } | |
340 | ||
341 | if (gre_add_protocol(&ipgre_protocol, GREPROTO_CISCO) < 0) { | |
342 | pr_info("%s: can't add ipgre handler\n", __func__); | |
343 | goto err_gre; | |
00959ade DK |
344 | } |
345 | ||
346 | return 0; | |
bda7bb46 PS |
347 | err_gre: |
348 | inet_del_protocol(&net_gre_protocol, IPPROTO_GRE); | |
349 | err: | |
350 | return -EAGAIN; | |
00959ade DK |
351 | } |
352 | ||
353 | static void __exit gre_exit(void) | |
354 | { | |
bda7bb46 | 355 | gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO); |
00959ade DK |
356 | inet_del_protocol(&net_gre_protocol, IPPROTO_GRE); |
357 | } | |
358 | ||
359 | module_init(gre_init); | |
360 | module_exit(gre_exit); | |
361 | ||
362 | MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver"); | |
363 | MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)"); | |
364 | MODULE_LICENSE("GPL"); |