net: convert BUG_TRAP to generic WARN_ON
[linux-2.6.git] / net / ipv6 / mip6.c
1 /*
2  * Copyright (C)2003-2006 Helsinki University of Technology
3  * Copyright (C)2003-2006 USAGI/WIDE Project
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License as published by
7  * the Free Software Foundation; either version 2 of the License, or
8  * (at your option) any later version.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  * GNU General Public License for more details.
14  *
15  * You should have received a copy of the GNU General Public License
16  * along with this program; if not, write to the Free Software
17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18  */
19 /*
20  * Authors:
21  *      Noriaki TAKAMIYA @USAGI
22  *      Masahide NAKAMURA @USAGI
23  */
24
25 #include <linux/module.h>
26 #include <linux/skbuff.h>
27 #include <linux/time.h>
28 #include <linux/ipv6.h>
29 #include <linux/icmpv6.h>
30 #include <net/sock.h>
31 #include <net/ipv6.h>
32 #include <net/ip6_checksum.h>
33 #include <net/rawv6.h>
34 #include <net/xfrm.h>
35 #include <net/mip6.h>
36
37 static inline unsigned int calc_padlen(unsigned int len, unsigned int n)
38 {
39         return (n - len + 16) & 0x7;
40 }
41
42 static inline void *mip6_padn(__u8 *data, __u8 padlen)
43 {
44         if (!data)
45                 return NULL;
46         if (padlen == 1) {
47                 data[0] = IPV6_TLV_PAD0;
48         } else if (padlen > 1) {
49                 data[0] = IPV6_TLV_PADN;
50                 data[1] = padlen - 2;
51                 if (padlen > 2)
52                         memset(data+2, 0, data[1]);
53         }
54         return data + padlen;
55 }
56
57 static inline void mip6_param_prob(struct sk_buff *skb, int code, int pos)
58 {
59         icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos, skb->dev);
60 }
61
62 static int mip6_mh_len(int type)
63 {
64         int len = 0;
65
66         switch (type) {
67         case IP6_MH_TYPE_BRR:
68                 len = 0;
69                 break;
70         case IP6_MH_TYPE_HOTI:
71         case IP6_MH_TYPE_COTI:
72         case IP6_MH_TYPE_BU:
73         case IP6_MH_TYPE_BACK:
74                 len = 1;
75                 break;
76         case IP6_MH_TYPE_HOT:
77         case IP6_MH_TYPE_COT:
78         case IP6_MH_TYPE_BERROR:
79                 len = 2;
80                 break;
81         }
82         return len;
83 }
84
85 static int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
86 {
87         struct ip6_mh *mh;
88
89         if (!pskb_may_pull(skb, (skb_transport_offset(skb)) + 8) ||
90             !pskb_may_pull(skb, (skb_transport_offset(skb) +
91                                  ((skb_transport_header(skb)[1] + 1) << 3))))
92                 return -1;
93
94         mh = (struct ip6_mh *)skb_transport_header(skb);
95
96         if (mh->ip6mh_hdrlen < mip6_mh_len(mh->ip6mh_type)) {
97                 LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH message too short: %d vs >=%d\n",
98                                mh->ip6mh_hdrlen, mip6_mh_len(mh->ip6mh_type));
99                 mip6_param_prob(skb, 0, ((&mh->ip6mh_hdrlen) -
100                                          skb_network_header(skb)));
101                 return -1;
102         }
103
104         if (mh->ip6mh_proto != IPPROTO_NONE) {
105                 LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH invalid payload proto = %d\n",
106                                mh->ip6mh_proto);
107                 mip6_param_prob(skb, 0, ((&mh->ip6mh_proto) -
108                                          skb_network_header(skb)));
109                 return -1;
110         }
111
112         return 0;
113 }
114
115 struct mip6_report_rate_limiter {
116         spinlock_t lock;
117         struct timeval stamp;
118         int iif;
119         struct in6_addr src;
120         struct in6_addr dst;
121 };
122
123 static struct mip6_report_rate_limiter mip6_report_rl = {
124         .lock = __SPIN_LOCK_UNLOCKED(mip6_report_rl.lock)
125 };
126
127 static int mip6_destopt_input(struct xfrm_state *x, struct sk_buff *skb)
128 {
129         struct ipv6hdr *iph = ipv6_hdr(skb);
130         struct ipv6_destopt_hdr *destopt = (struct ipv6_destopt_hdr *)skb->data;
131         int err = destopt->nexthdr;
132
133         spin_lock(&x->lock);
134         if (!ipv6_addr_equal(&iph->saddr, (struct in6_addr *)x->coaddr) &&
135             !ipv6_addr_any((struct in6_addr *)x->coaddr))
136                 err = -ENOENT;
137         spin_unlock(&x->lock);
138
139         return err;
140 }
141
142 /* Destination Option Header is inserted.
143  * IP Header's src address is replaced with Home Address Option in
144  * Destination Option Header.
145  */
146 static int mip6_destopt_output(struct xfrm_state *x, struct sk_buff *skb)
147 {
148         struct ipv6hdr *iph;
149         struct ipv6_destopt_hdr *dstopt;
150         struct ipv6_destopt_hao *hao;
151         u8 nexthdr;
152         int len;
153
154         skb_push(skb, -skb_network_offset(skb));
155         iph = ipv6_hdr(skb);
156
157         nexthdr = *skb_mac_header(skb);
158         *skb_mac_header(skb) = IPPROTO_DSTOPTS;
159
160         dstopt = (struct ipv6_destopt_hdr *)skb_transport_header(skb);
161         dstopt->nexthdr = nexthdr;
162
163         hao = mip6_padn((char *)(dstopt + 1),
164                         calc_padlen(sizeof(*dstopt), 6));
165
166         hao->type = IPV6_TLV_HAO;
167         BUILD_BUG_ON(sizeof(*hao) != 18);
168         hao->length = sizeof(*hao) - 2;
169
170         len = ((char *)hao - (char *)dstopt) + sizeof(*hao);
171
172         memcpy(&hao->addr, &iph->saddr, sizeof(hao->addr));
173         spin_lock_bh(&x->lock);
174         memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
175         spin_unlock_bh(&x->lock);
176
177         WARN_ON(len != x->props.header_len);
178         dstopt->hdrlen = (x->props.header_len >> 3) - 1;
179
180         return 0;
181 }
182
183 static inline int mip6_report_rl_allow(struct timeval *stamp,
184                                        struct in6_addr *dst,
185                                        struct in6_addr *src, int iif)
186 {
187         int allow = 0;
188
189         spin_lock_bh(&mip6_report_rl.lock);
190         if (mip6_report_rl.stamp.tv_sec != stamp->tv_sec ||
191             mip6_report_rl.stamp.tv_usec != stamp->tv_usec ||
192             mip6_report_rl.iif != iif ||
193             !ipv6_addr_equal(&mip6_report_rl.src, src) ||
194             !ipv6_addr_equal(&mip6_report_rl.dst, dst)) {
195                 mip6_report_rl.stamp.tv_sec = stamp->tv_sec;
196                 mip6_report_rl.stamp.tv_usec = stamp->tv_usec;
197                 mip6_report_rl.iif = iif;
198                 ipv6_addr_copy(&mip6_report_rl.src, src);
199                 ipv6_addr_copy(&mip6_report_rl.dst, dst);
200                 allow = 1;
201         }
202         spin_unlock_bh(&mip6_report_rl.lock);
203         return allow;
204 }
205
206 static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb, struct flowi *fl)
207 {
208         struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
209         struct ipv6_destopt_hao *hao = NULL;
210         struct xfrm_selector sel;
211         int offset;
212         struct timeval stamp;
213         int err = 0;
214
215         if (unlikely(fl->proto == IPPROTO_MH &&
216                      fl->fl_mh_type <= IP6_MH_TYPE_MAX))
217                 goto out;
218
219         if (likely(opt->dsthao)) {
220                 offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
221                 if (likely(offset >= 0))
222                         hao = (struct ipv6_destopt_hao *)
223                                         (skb_network_header(skb) + offset);
224         }
225
226         skb_get_timestamp(skb, &stamp);
227
228         if (!mip6_report_rl_allow(&stamp, &ipv6_hdr(skb)->daddr,
229                                   hao ? &hao->addr : &ipv6_hdr(skb)->saddr,
230                                   opt->iif))
231                 goto out;
232
233         memset(&sel, 0, sizeof(sel));
234         memcpy(&sel.daddr, (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
235                sizeof(sel.daddr));
236         sel.prefixlen_d = 128;
237         memcpy(&sel.saddr, (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
238                sizeof(sel.saddr));
239         sel.prefixlen_s = 128;
240         sel.family = AF_INET6;
241         sel.proto = fl->proto;
242         sel.dport = xfrm_flowi_dport(fl);
243         if (sel.dport)
244                 sel.dport_mask = htons(~0);
245         sel.sport = xfrm_flowi_sport(fl);
246         if (sel.sport)
247                 sel.sport_mask = htons(~0);
248         sel.ifindex = fl->oif;
249
250         err = km_report(IPPROTO_DSTOPTS, &sel,
251                         (hao ? (xfrm_address_t *)&hao->addr : NULL));
252
253  out:
254         return err;
255 }
256
257 static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
258                                u8 **nexthdr)
259 {
260         u16 offset = sizeof(struct ipv6hdr);
261         struct ipv6_opt_hdr *exthdr =
262                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
263         const unsigned char *nh = skb_network_header(skb);
264         unsigned int packet_len = skb->tail - skb->network_header;
265         int found_rhdr = 0;
266
267         *nexthdr = &ipv6_hdr(skb)->nexthdr;
268
269         while (offset + 1 <= packet_len) {
270
271                 switch (**nexthdr) {
272                 case NEXTHDR_HOP:
273                         break;
274                 case NEXTHDR_ROUTING:
275                         found_rhdr = 1;
276                         break;
277                 case NEXTHDR_DEST:
278                         /*
279                          * HAO MUST NOT appear more than once.
280                          * XXX: It is better to try to find by the end of
281                          * XXX: packet if HAO exists.
282                          */
283                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
284                                 LIMIT_NETDEBUG(KERN_WARNING "mip6: hao exists already, override\n");
285                                 return offset;
286                         }
287
288                         if (found_rhdr)
289                                 return offset;
290
291                         break;
292                 default:
293                         return offset;
294                 }
295
296                 offset += ipv6_optlen(exthdr);
297                 *nexthdr = &exthdr->nexthdr;
298                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
299         }
300
301         return offset;
302 }
303
304 static int mip6_destopt_init_state(struct xfrm_state *x)
305 {
306         if (x->id.spi) {
307                 printk(KERN_INFO "%s: spi is not 0: %u\n", __func__,
308                        x->id.spi);
309                 return -EINVAL;
310         }
311         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
312                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
313                        __func__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
314                 return -EINVAL;
315         }
316
317         x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
318                 calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
319                 sizeof(struct ipv6_destopt_hao);
320         WARN_ON(x->props.header_len != 24);
321
322         return 0;
323 }
324
325 /*
326  * Do nothing about destroying since it has no specific operation for
327  * destination options header unlike IPsec protocols.
328  */
329 static void mip6_destopt_destroy(struct xfrm_state *x)
330 {
331 }
332
333 static const struct xfrm_type mip6_destopt_type =
334 {
335         .description    = "MIP6DESTOPT",
336         .owner          = THIS_MODULE,
337         .proto          = IPPROTO_DSTOPTS,
338         .flags          = XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_LOCAL_COADDR,
339         .init_state     = mip6_destopt_init_state,
340         .destructor     = mip6_destopt_destroy,
341         .input          = mip6_destopt_input,
342         .output         = mip6_destopt_output,
343         .reject         = mip6_destopt_reject,
344         .hdr_offset     = mip6_destopt_offset,
345 };
346
347 static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
348 {
349         struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
350         int err = rt2->rt_hdr.nexthdr;
351
352         spin_lock(&x->lock);
353         if (!ipv6_addr_equal(&rt2->addr, (struct in6_addr *)x->coaddr) &&
354             !ipv6_addr_any((struct in6_addr *)x->coaddr))
355                 err = -ENOENT;
356         spin_unlock(&x->lock);
357
358         return err;
359 }
360
361 /* Routing Header type 2 is inserted.
362  * IP Header's dst address is replaced with Routing Header's Home Address.
363  */
364 static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
365 {
366         struct ipv6hdr *iph;
367         struct rt2_hdr *rt2;
368         u8 nexthdr;
369
370         skb_push(skb, -skb_network_offset(skb));
371         iph = ipv6_hdr(skb);
372
373         nexthdr = *skb_mac_header(skb);
374         *skb_mac_header(skb) = IPPROTO_ROUTING;
375
376         rt2 = (struct rt2_hdr *)skb_transport_header(skb);
377         rt2->rt_hdr.nexthdr = nexthdr;
378         rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
379         rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
380         rt2->rt_hdr.segments_left = 1;
381         memset(&rt2->reserved, 0, sizeof(rt2->reserved));
382
383         WARN_ON(rt2->rt_hdr.hdrlen != 2);
384
385         memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
386         spin_lock_bh(&x->lock);
387         memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
388         spin_unlock_bh(&x->lock);
389
390         return 0;
391 }
392
393 static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
394                              u8 **nexthdr)
395 {
396         u16 offset = sizeof(struct ipv6hdr);
397         struct ipv6_opt_hdr *exthdr =
398                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
399         const unsigned char *nh = skb_network_header(skb);
400         unsigned int packet_len = skb->tail - skb->network_header;
401         int found_rhdr = 0;
402
403         *nexthdr = &ipv6_hdr(skb)->nexthdr;
404
405         while (offset + 1 <= packet_len) {
406
407                 switch (**nexthdr) {
408                 case NEXTHDR_HOP:
409                         break;
410                 case NEXTHDR_ROUTING:
411                         if (offset + 3 <= packet_len) {
412                                 struct ipv6_rt_hdr *rt;
413                                 rt = (struct ipv6_rt_hdr *)(nh + offset);
414                                 if (rt->type != 0)
415                                         return offset;
416                         }
417                         found_rhdr = 1;
418                         break;
419                 case NEXTHDR_DEST:
420                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
421                                 return offset;
422
423                         if (found_rhdr)
424                                 return offset;
425
426                         break;
427                 default:
428                         return offset;
429                 }
430
431                 offset += ipv6_optlen(exthdr);
432                 *nexthdr = &exthdr->nexthdr;
433                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
434         }
435
436         return offset;
437 }
438
439 static int mip6_rthdr_init_state(struct xfrm_state *x)
440 {
441         if (x->id.spi) {
442                 printk(KERN_INFO "%s: spi is not 0: %u\n", __func__,
443                        x->id.spi);
444                 return -EINVAL;
445         }
446         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
447                 printk(KERN_INFO "%s: state's mode is not %u: %u\n",
448                        __func__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
449                 return -EINVAL;
450         }
451
452         x->props.header_len = sizeof(struct rt2_hdr);
453
454         return 0;
455 }
456
457 /*
458  * Do nothing about destroying since it has no specific operation for routing
459  * header type 2 unlike IPsec protocols.
460  */
461 static void mip6_rthdr_destroy(struct xfrm_state *x)
462 {
463 }
464
465 static const struct xfrm_type mip6_rthdr_type =
466 {
467         .description    = "MIP6RT",
468         .owner          = THIS_MODULE,
469         .proto          = IPPROTO_ROUTING,
470         .flags          = XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_REMOTE_COADDR,
471         .init_state     = mip6_rthdr_init_state,
472         .destructor     = mip6_rthdr_destroy,
473         .input          = mip6_rthdr_input,
474         .output         = mip6_rthdr_output,
475         .hdr_offset     = mip6_rthdr_offset,
476 };
477
478 static int __init mip6_init(void)
479 {
480         printk(KERN_INFO "Mobile IPv6\n");
481
482         if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
483                 printk(KERN_INFO "%s: can't add xfrm type(destopt)\n", __func__);
484                 goto mip6_destopt_xfrm_fail;
485         }
486         if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
487                 printk(KERN_INFO "%s: can't add xfrm type(rthdr)\n", __func__);
488                 goto mip6_rthdr_xfrm_fail;
489         }
490         if (rawv6_mh_filter_register(mip6_mh_filter) < 0) {
491                 printk(KERN_INFO "%s: can't add rawv6 mh filter\n", __func__);
492                 goto mip6_rawv6_mh_fail;
493         }
494
495
496         return 0;
497
498  mip6_rawv6_mh_fail:
499         xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
500  mip6_rthdr_xfrm_fail:
501         xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
502  mip6_destopt_xfrm_fail:
503         return -EAGAIN;
504 }
505
506 static void __exit mip6_fini(void)
507 {
508         if (rawv6_mh_filter_unregister(mip6_mh_filter) < 0)
509                 printk(KERN_INFO "%s: can't remove rawv6 mh filter\n", __func__);
510         if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
511                 printk(KERN_INFO "%s: can't remove xfrm type(rthdr)\n", __func__);
512         if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
513                 printk(KERN_INFO "%s: can't remove xfrm type(destopt)\n", __func__);
514 }
515
516 module_init(mip6_init);
517 module_exit(mip6_fini);
518
519 MODULE_LICENSE("GPL");
520 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_DSTOPTS);
521 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ROUTING);