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5ebaf571 PS |
1 | /* |
2 | * Copyright (c) 2007-2013 Nicira, Inc. | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of version 2 of the GNU General Public | |
6 | * License as published by the Free Software Foundation. | |
7 | * | |
8 | * This program is distributed in the hope that it will be useful, but | |
9 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
11 | * General Public License for more details. | |
12 | * | |
13 | * You should have received a copy of the GNU General Public License | |
14 | * along with this program; if not, write to the Free Software | |
15 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA | |
16 | * 02110-1301, USA | |
17 | */ | |
18 | ||
19 | #include <linux/module.h> | |
20 | #include <linux/if.h> | |
21 | #include <linux/if_tunnel.h> | |
22 | #include <linux/icmp.h> | |
23 | #include <linux/in.h> | |
24 | #include <linux/ip.h> | |
25 | #include <linux/kernel.h> | |
26 | #include <linux/kmod.h> | |
27 | #include <linux/netdevice.h> | |
28 | #include <linux/skbuff.h> | |
29 | #include <linux/spinlock.h> | |
30 | ||
31 | #include <net/gre.h> | |
32 | #include <net/icmp.h> | |
33 | #include <net/protocol.h> | |
34 | #include <net/route.h> | |
35 | #include <net/xfrm.h> | |
36 | ||
37 | #include "gso.h" | |
38 | ||
39 | static struct gre_cisco_protocol __rcu *gre_cisco_proto; | |
40 | ||
41 | static void gre_csum_fix(struct sk_buff *skb) | |
42 | { | |
43 | struct gre_base_hdr *greh; | |
44 | __be32 *options; | |
45 | int gre_offset = skb_transport_offset(skb); | |
46 | ||
47 | greh = (struct gre_base_hdr *)skb_transport_header(skb); | |
48 | options = ((__be32 *)greh + 1); | |
49 | ||
50 | *options = 0; | |
51 | *(__sum16 *)options = csum_fold(skb_checksum(skb, gre_offset, | |
52 | skb->len - gre_offset, 0)); | |
53 | } | |
54 | ||
55 | struct sk_buff *gre_handle_offloads(struct sk_buff *skb, bool gre_csum) | |
56 | { | |
57 | int err; | |
58 | ||
59 | skb_reset_inner_headers(skb); | |
60 | ||
61 | if (skb_is_gso(skb)) { | |
62 | if (gre_csum) | |
63 | OVS_GSO_CB(skb)->fix_segment = gre_csum_fix; | |
64 | } else { | |
65 | if (skb->ip_summed == CHECKSUM_PARTIAL && gre_csum) { | |
66 | err = skb_checksum_help(skb); | |
67 | if (err) | |
68 | goto error; | |
69 | ||
70 | } else if (skb->ip_summed != CHECKSUM_PARTIAL) | |
71 | skb->ip_summed = CHECKSUM_NONE; | |
72 | } | |
73 | return skb; | |
74 | error: | |
75 | kfree_skb(skb); | |
76 | return ERR_PTR(err); | |
77 | } | |
78 | ||
79 | static bool is_gre_gso(struct sk_buff *skb) | |
80 | { | |
81 | return skb_is_gso(skb); | |
82 | } | |
83 | ||
84 | void gre_build_header(struct sk_buff *skb, const struct tnl_ptk_info *tpi, | |
85 | int hdr_len) | |
86 | { | |
87 | struct gre_base_hdr *greh; | |
88 | ||
89 | __skb_push(skb, hdr_len); | |
90 | ||
91 | greh = (struct gre_base_hdr *)skb->data; | |
92 | greh->flags = tnl_flags_to_gre_flags(tpi->flags); | |
93 | greh->protocol = tpi->proto; | |
94 | ||
95 | if (tpi->flags & (TUNNEL_KEY | TUNNEL_CSUM | TUNNEL_SEQ)) { | |
96 | __be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4); | |
97 | ||
98 | if (tpi->flags & TUNNEL_SEQ) { | |
99 | *ptr = tpi->seq; | |
100 | ptr--; | |
101 | } | |
102 | if (tpi->flags & TUNNEL_KEY) { | |
103 | *ptr = tpi->key; | |
104 | ptr--; | |
105 | } | |
106 | if (tpi->flags & TUNNEL_CSUM && !is_gre_gso(skb)) { | |
107 | *ptr = 0; | |
108 | *(__sum16 *)ptr = csum_fold(skb_checksum(skb, 0, | |
109 | skb->len, 0)); | |
110 | } | |
111 | } | |
112 | } | |
113 | ||
114 | static __sum16 check_checksum(struct sk_buff *skb) | |
115 | { | |
116 | __sum16 csum = 0; | |
117 | ||
118 | switch (skb->ip_summed) { | |
119 | case CHECKSUM_COMPLETE: | |
120 | csum = csum_fold(skb->csum); | |
121 | ||
122 | if (!csum) | |
123 | break; | |
124 | /* Fall through. */ | |
125 | ||
126 | case CHECKSUM_NONE: | |
127 | skb->csum = 0; | |
128 | csum = __skb_checksum_complete(skb); | |
129 | skb->ip_summed = CHECKSUM_COMPLETE; | |
130 | break; | |
131 | } | |
132 | ||
133 | return csum; | |
134 | } | |
135 | ||
136 | static int parse_gre_header(struct sk_buff *skb, struct tnl_ptk_info *tpi, | |
137 | bool *csum_err) | |
138 | { | |
139 | unsigned int ip_hlen = ip_hdrlen(skb); | |
140 | struct gre_base_hdr *greh; | |
141 | __be32 *options; | |
142 | int hdr_len; | |
143 | ||
144 | if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr)))) | |
145 | return -EINVAL; | |
146 | ||
147 | greh = (struct gre_base_hdr *)(skb_network_header(skb) + ip_hlen); | |
148 | if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING))) | |
149 | return -EINVAL; | |
150 | ||
151 | tpi->flags = gre_flags_to_tnl_flags(greh->flags); | |
152 | hdr_len = ip_gre_calc_hlen(tpi->flags); | |
153 | ||
154 | if (!pskb_may_pull(skb, hdr_len)) | |
155 | return -EINVAL; | |
156 | ||
157 | greh = (struct gre_base_hdr *)(skb_network_header(skb) + ip_hlen); | |
158 | tpi->proto = greh->protocol; | |
159 | ||
160 | options = (__be32 *)(greh + 1); | |
161 | if (greh->flags & GRE_CSUM) { | |
162 | if (check_checksum(skb)) { | |
163 | *csum_err = true; | |
164 | return -EINVAL; | |
165 | } | |
166 | options++; | |
167 | } | |
168 | ||
169 | if (greh->flags & GRE_KEY) { | |
170 | tpi->key = *options; | |
171 | options++; | |
172 | } else | |
173 | tpi->key = 0; | |
174 | ||
175 | if (unlikely(greh->flags & GRE_SEQ)) { | |
176 | tpi->seq = *options; | |
177 | options++; | |
178 | } else | |
179 | tpi->seq = 0; | |
180 | ||
181 | /* WCCP version 1 and 2 protocol decoding. | |
182 | * - Change protocol to IP | |
183 | * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header | |
184 | */ | |
185 | if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) { | |
186 | tpi->proto = htons(ETH_P_IP); | |
187 | if ((*(u8 *)options & 0xF0) != 0x40) { | |
188 | hdr_len += 4; | |
189 | if (!pskb_may_pull(skb, hdr_len)) | |
190 | return -EINVAL; | |
191 | } | |
192 | } | |
193 | ||
194 | return iptunnel_pull_header(skb, hdr_len, tpi->proto); | |
195 | } | |
196 | ||
197 | static int gre_cisco_rcv(struct sk_buff *skb) | |
198 | { | |
199 | struct tnl_ptk_info tpi; | |
200 | bool csum_err = false; | |
201 | struct gre_cisco_protocol *proto; | |
202 | ||
203 | rcu_read_lock(); | |
204 | proto = rcu_dereference(gre_cisco_proto); | |
205 | if (!proto) | |
206 | goto drop; | |
207 | ||
208 | if (parse_gre_header(skb, &tpi, &csum_err) < 0) | |
209 | goto drop; | |
210 | proto->handler(skb, &tpi); | |
211 | rcu_read_unlock(); | |
212 | return 0; | |
213 | ||
214 | drop: | |
215 | rcu_read_unlock(); | |
216 | kfree_skb(skb); | |
217 | return 0; | |
218 | } | |
219 | ||
220 | static const struct gre_protocol ipgre_protocol = { | |
221 | .handler = gre_cisco_rcv, | |
222 | }; | |
223 | ||
224 | #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,37) | |
225 | static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly; | |
226 | ||
227 | int gre_add_protocol(const struct gre_protocol *proto, u8 version) | |
228 | { | |
229 | if (version >= GREPROTO_MAX) | |
230 | return -EINVAL; | |
231 | ||
232 | return (cmpxchg((const struct gre_protocol **)&gre_proto[version], NULL, proto) == NULL) ? | |
233 | 0 : -EBUSY; | |
234 | } | |
235 | ||
236 | int gre_del_protocol(const struct gre_protocol *proto, u8 version) | |
237 | { | |
238 | int ret; | |
239 | ||
240 | if (version >= GREPROTO_MAX) | |
241 | return -EINVAL; | |
242 | ||
243 | ret = (cmpxchg((const struct gre_protocol **)&gre_proto[version], proto, NULL) == proto) ? | |
244 | 0 : -EBUSY; | |
245 | ||
246 | if (ret) | |
247 | return ret; | |
248 | ||
249 | synchronize_net(); | |
250 | return 0; | |
251 | } | |
252 | ||
253 | static int gre_rcv(struct sk_buff *skb) | |
254 | { | |
255 | const struct gre_protocol *proto; | |
256 | u8 ver; | |
257 | int ret; | |
258 | ||
259 | if (!pskb_may_pull(skb, 12)) | |
260 | goto drop; | |
261 | ||
262 | ver = skb->data[1] & 0x7f; | |
263 | if (ver >= GREPROTO_MAX) | |
264 | goto drop; | |
265 | ||
266 | rcu_read_lock(); | |
267 | proto = rcu_dereference(gre_proto[ver]); | |
268 | if (!proto || !proto->handler) | |
269 | goto drop_unlock; | |
270 | ret = proto->handler(skb); | |
271 | rcu_read_unlock(); | |
272 | return ret; | |
273 | ||
274 | drop_unlock: | |
275 | rcu_read_unlock(); | |
276 | drop: | |
277 | kfree_skb(skb); | |
278 | return NET_RX_DROP; | |
279 | } | |
280 | ||
281 | static const struct net_protocol net_gre_protocol = { | |
282 | .handler = gre_rcv, | |
283 | #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,32) | |
284 | .netns_ok = 1, | |
285 | #endif | |
286 | }; | |
287 | #endif | |
288 | ||
289 | static int gre_compat_init(void) | |
290 | { | |
291 | int err; | |
292 | ||
293 | #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,37) | |
294 | if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) { | |
295 | pr_err("%s: cannot register gre protocol handler\n", __func__); | |
296 | return -EAGAIN; | |
297 | } | |
298 | #endif | |
299 | err = gre_add_protocol(&ipgre_protocol, GREPROTO_CISCO); | |
300 | if (err) { | |
301 | pr_warn("%s: cannot register gre_cisco protocol handler\n", __func__); | |
302 | ||
303 | #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,37) | |
304 | inet_del_protocol(&net_gre_protocol, IPPROTO_GRE); | |
305 | #endif | |
306 | } | |
307 | ||
308 | return err; | |
309 | } | |
310 | ||
311 | static int gre_compat_exit(void) | |
312 | { | |
313 | int ret; | |
314 | ||
315 | ret = gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO); | |
316 | if (ret) | |
317 | return ret; | |
318 | ||
319 | #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,37) | |
320 | ret = inet_del_protocol(&net_gre_protocol, IPPROTO_GRE); | |
321 | if (ret) | |
322 | return ret; | |
323 | #endif | |
324 | return 0; | |
325 | } | |
326 | ||
327 | int gre_cisco_register(struct gre_cisco_protocol *newp) | |
328 | { | |
329 | int err; | |
330 | ||
331 | err = gre_compat_init(); | |
332 | if (err) | |
333 | return err; | |
334 | ||
335 | return (cmpxchg((struct gre_cisco_protocol **)&gre_cisco_proto, NULL, newp) == NULL) ? | |
336 | 0 : -EBUSY; | |
337 | } | |
338 | ||
339 | int gre_cisco_unregister(struct gre_cisco_protocol *proto) | |
340 | { | |
341 | int ret; | |
342 | ||
343 | ret = (cmpxchg((struct gre_cisco_protocol **)&gre_cisco_proto, proto, NULL) == proto) ? | |
344 | 0 : -EINVAL; | |
345 | ||
346 | if (ret) | |
347 | return ret; | |
348 | ||
349 | synchronize_net(); | |
350 | ret = gre_compat_exit(); | |
351 | return ret; | |
352 | } |