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TOMOYO Linux Cross Reference
Linux/net/ipv6/mip6.c

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  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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 26 
 27 #include <linux/module.h>
 28 #include <linux/skbuff.h>
 29 #include <linux/time.h>
 30 #include <linux/ipv6.h>
 31 #include <linux/icmpv6.h>
 32 #include <net/sock.h>
 33 #include <net/ipv6.h>
 34 #include <net/ip6_checksum.h>
 35 #include <net/rawv6.h>
 36 #include <net/xfrm.h>
 37 #include <net/mip6.h>
 38 
 39 static inline unsigned int calc_padlen(unsigned int len, unsigned int n)
 40 {
 41         return (n - len + 16) & 0x7;
 42 }
 43 
 44 static inline void *mip6_padn(__u8 *data, __u8 padlen)
 45 {
 46         if (!data)
 47                 return NULL;
 48         if (padlen == 1) {
 49                 data[0] = IPV6_TLV_PAD1;
 50         } else if (padlen > 1) {
 51                 data[0] = IPV6_TLV_PADN;
 52                 data[1] = padlen - 2;
 53                 if (padlen > 2)
 54                         memset(data+2, 0, data[1]);
 55         }
 56         return data + padlen;
 57 }
 58 
 59 static inline void mip6_param_prob(struct sk_buff *skb, u8 code, int pos)
 60 {
 61         icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos);
 62 }
 63 
 64 static int mip6_mh_len(int type)
 65 {
 66         int len = 0;
 67 
 68         switch (type) {
 69         case IP6_MH_TYPE_BRR:
 70                 len = 0;
 71                 break;
 72         case IP6_MH_TYPE_HOTI:
 73         case IP6_MH_TYPE_COTI:
 74         case IP6_MH_TYPE_BU:
 75         case IP6_MH_TYPE_BACK:
 76                 len = 1;
 77                 break;
 78         case IP6_MH_TYPE_HOT:
 79         case IP6_MH_TYPE_COT:
 80         case IP6_MH_TYPE_BERROR:
 81                 len = 2;
 82                 break;
 83         }
 84         return len;
 85 }
 86 
 87 static int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
 88 {
 89         struct ip6_mh _hdr;
 90         const struct ip6_mh *mh;
 91 
 92         mh = skb_header_pointer(skb, skb_transport_offset(skb),
 93                                 sizeof(_hdr), &_hdr);
 94         if (!mh)
 95                 return -1;
 96 
 97         if (((mh->ip6mh_hdrlen + 1) << 3) > skb->len)
 98                 return -1;
 99 
100         if (mh->ip6mh_hdrlen < mip6_mh_len(mh->ip6mh_type)) {
101                 LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH message too short: %d vs >=%d\n",
102                                mh->ip6mh_hdrlen, mip6_mh_len(mh->ip6mh_type));
103                 mip6_param_prob(skb, 0, offsetof(struct ip6_mh, ip6mh_hdrlen) +
104                                 skb_network_header_len(skb));
105                 return -1;
106         }
107 
108         if (mh->ip6mh_proto != IPPROTO_NONE) {
109                 LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH invalid payload proto = %d\n",
110                                mh->ip6mh_proto);
111                 mip6_param_prob(skb, 0, offsetof(struct ip6_mh, ip6mh_proto) +
112                                 skb_network_header_len(skb));
113                 return -1;
114         }
115 
116         return 0;
117 }
118 
119 struct mip6_report_rate_limiter {
120         spinlock_t lock;
121         struct timeval stamp;
122         int iif;
123         struct in6_addr src;
124         struct in6_addr dst;
125 };
126 
127 static struct mip6_report_rate_limiter mip6_report_rl = {
128         .lock = __SPIN_LOCK_UNLOCKED(mip6_report_rl.lock)
129 };
130 
131 static int mip6_destopt_input(struct xfrm_state *x, struct sk_buff *skb)
132 {
133         const struct ipv6hdr *iph = ipv6_hdr(skb);
134         struct ipv6_destopt_hdr *destopt = (struct ipv6_destopt_hdr *)skb->data;
135         int err = destopt->nexthdr;
136 
137         spin_lock(&x->lock);
138         if (!ipv6_addr_equal(&iph->saddr, (struct in6_addr *)x->coaddr) &&
139             !ipv6_addr_any((struct in6_addr *)x->coaddr))
140                 err = -ENOENT;
141         spin_unlock(&x->lock);
142 
143         return err;
144 }
145 
146 /* Destination Option Header is inserted.
147  * IP Header's src address is replaced with Home Address Option in
148  * Destination Option Header.
149  */
150 static int mip6_destopt_output(struct xfrm_state *x, struct sk_buff *skb)
151 {
152         struct ipv6hdr *iph;
153         struct ipv6_destopt_hdr *dstopt;
154         struct ipv6_destopt_hao *hao;
155         u8 nexthdr;
156         int len;
157 
158         skb_push(skb, -skb_network_offset(skb));
159         iph = ipv6_hdr(skb);
160 
161         nexthdr = *skb_mac_header(skb);
162         *skb_mac_header(skb) = IPPROTO_DSTOPTS;
163 
164         dstopt = (struct ipv6_destopt_hdr *)skb_transport_header(skb);
165         dstopt->nexthdr = nexthdr;
166 
167         hao = mip6_padn((char *)(dstopt + 1),
168                         calc_padlen(sizeof(*dstopt), 6));
169 
170         hao->type = IPV6_TLV_HAO;
171         BUILD_BUG_ON(sizeof(*hao) != 18);
172         hao->length = sizeof(*hao) - 2;
173 
174         len = ((char *)hao - (char *)dstopt) + sizeof(*hao);
175 
176         memcpy(&hao->addr, &iph->saddr, sizeof(hao->addr));
177         spin_lock_bh(&x->lock);
178         memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
179         spin_unlock_bh(&x->lock);
180 
181         WARN_ON(len != x->props.header_len);
182         dstopt->hdrlen = (x->props.header_len >> 3) - 1;
183 
184         return 0;
185 }
186 
187 static inline int mip6_report_rl_allow(struct timeval *stamp,
188                                        const struct in6_addr *dst,
189                                        const struct in6_addr *src, int iif)
190 {
191         int allow = 0;
192 
193         spin_lock_bh(&mip6_report_rl.lock);
194         if (mip6_report_rl.stamp.tv_sec != stamp->tv_sec ||
195             mip6_report_rl.stamp.tv_usec != stamp->tv_usec ||
196             mip6_report_rl.iif != iif ||
197             !ipv6_addr_equal(&mip6_report_rl.src, src) ||
198             !ipv6_addr_equal(&mip6_report_rl.dst, dst)) {
199                 mip6_report_rl.stamp.tv_sec = stamp->tv_sec;
200                 mip6_report_rl.stamp.tv_usec = stamp->tv_usec;
201                 mip6_report_rl.iif = iif;
202                 mip6_report_rl.src = *src;
203                 mip6_report_rl.dst = *dst;
204                 allow = 1;
205         }
206         spin_unlock_bh(&mip6_report_rl.lock);
207         return allow;
208 }
209 
210 static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb,
211                                const struct flowi *fl)
212 {
213         struct net *net = xs_net(x);
214         struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
215         const struct flowi6 *fl6 = &fl->u.ip6;
216         struct ipv6_destopt_hao *hao = NULL;
217         struct xfrm_selector sel;
218         int offset;
219         struct timeval stamp;
220         int err = 0;
221 
222         if (unlikely(fl6->flowi6_proto == IPPROTO_MH &&
223                      fl6->fl6_mh_type <= IP6_MH_TYPE_MAX))
224                 goto out;
225 
226         if (likely(opt->dsthao)) {
227                 offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
228                 if (likely(offset >= 0))
229                         hao = (struct ipv6_destopt_hao *)
230                                         (skb_network_header(skb) + offset);
231         }
232 
233         skb_get_timestamp(skb, &stamp);
234 
235         if (!mip6_report_rl_allow(&stamp, &ipv6_hdr(skb)->daddr,
236                                   hao ? &hao->addr : &ipv6_hdr(skb)->saddr,
237                                   opt->iif))
238                 goto out;
239 
240         memset(&sel, 0, sizeof(sel));
241         memcpy(&sel.daddr, (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
242                sizeof(sel.daddr));
243         sel.prefixlen_d = 128;
244         memcpy(&sel.saddr, (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
245                sizeof(sel.saddr));
246         sel.prefixlen_s = 128;
247         sel.family = AF_INET6;
248         sel.proto = fl6->flowi6_proto;
249         sel.dport = xfrm_flowi_dport(fl, &fl6->uli);
250         if (sel.dport)
251                 sel.dport_mask = htons(~0);
252         sel.sport = xfrm_flowi_sport(fl, &fl6->uli);
253         if (sel.sport)
254                 sel.sport_mask = htons(~0);
255         sel.ifindex = fl6->flowi6_oif;
256 
257         err = km_report(net, IPPROTO_DSTOPTS, &sel,
258                         (hao ? (xfrm_address_t *)&hao->addr : NULL));
259 
260  out:
261         return err;
262 }
263 
264 static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
265                                u8 **nexthdr)
266 {
267         u16 offset = sizeof(struct ipv6hdr);
268         struct ipv6_opt_hdr *exthdr =
269                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
270         const unsigned char *nh = skb_network_header(skb);
271         unsigned int packet_len = skb_tail_pointer(skb) -
272                 skb_network_header(skb);
273         int found_rhdr = 0;
274 
275         *nexthdr = &ipv6_hdr(skb)->nexthdr;
276 
277         while (offset + 1 <= packet_len) {
278 
279                 switch (**nexthdr) {
280                 case NEXTHDR_HOP:
281                         break;
282                 case NEXTHDR_ROUTING:
283                         found_rhdr = 1;
284                         break;
285                 case NEXTHDR_DEST:
286                         /*
287                          * HAO MUST NOT appear more than once.
288                          * XXX: It is better to try to find by the end of
289                          * XXX: packet if HAO exists.
290                          */
291                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
292                                 LIMIT_NETDEBUG(KERN_WARNING "mip6: hao exists already, override\n");
293                                 return offset;
294                         }
295 
296                         if (found_rhdr)
297                                 return offset;
298 
299                         break;
300                 default:
301                         return offset;
302                 }
303 
304                 offset += ipv6_optlen(exthdr);
305                 *nexthdr = &exthdr->nexthdr;
306                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
307         }
308 
309         return offset;
310 }
311 
312 static int mip6_destopt_init_state(struct xfrm_state *x)
313 {
314         if (x->id.spi) {
315                 pr_info("%s: spi is not 0: %u\n", __func__, x->id.spi);
316                 return -EINVAL;
317         }
318         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
319                 pr_info("%s: state's mode is not %u: %u\n",
320                         __func__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
321                 return -EINVAL;
322         }
323 
324         x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
325                 calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
326                 sizeof(struct ipv6_destopt_hao);
327         WARN_ON(x->props.header_len != 24);
328 
329         return 0;
330 }
331 
332 /*
333  * Do nothing about destroying since it has no specific operation for
334  * destination options header unlike IPsec protocols.
335  */
336 static void mip6_destopt_destroy(struct xfrm_state *x)
337 {
338 }
339 
340 static const struct xfrm_type mip6_destopt_type =
341 {
342         .description    = "MIP6DESTOPT",
343         .owner          = THIS_MODULE,
344         .proto          = IPPROTO_DSTOPTS,
345         .flags          = XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_LOCAL_COADDR,
346         .init_state     = mip6_destopt_init_state,
347         .destructor     = mip6_destopt_destroy,
348         .input          = mip6_destopt_input,
349         .output         = mip6_destopt_output,
350         .reject         = mip6_destopt_reject,
351         .hdr_offset     = mip6_destopt_offset,
352 };
353 
354 static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
355 {
356         const struct ipv6hdr *iph = ipv6_hdr(skb);
357         struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
358         int err = rt2->rt_hdr.nexthdr;
359 
360         spin_lock(&x->lock);
361         if (!ipv6_addr_equal(&iph->daddr, (struct in6_addr *)x->coaddr) &&
362             !ipv6_addr_any((struct in6_addr *)x->coaddr))
363                 err = -ENOENT;
364         spin_unlock(&x->lock);
365 
366         return err;
367 }
368 
369 /* Routing Header type 2 is inserted.
370  * IP Header's dst address is replaced with Routing Header's Home Address.
371  */
372 static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
373 {
374         struct ipv6hdr *iph;
375         struct rt2_hdr *rt2;
376         u8 nexthdr;
377 
378         skb_push(skb, -skb_network_offset(skb));
379         iph = ipv6_hdr(skb);
380 
381         nexthdr = *skb_mac_header(skb);
382         *skb_mac_header(skb) = IPPROTO_ROUTING;
383 
384         rt2 = (struct rt2_hdr *)skb_transport_header(skb);
385         rt2->rt_hdr.nexthdr = nexthdr;
386         rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
387         rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
388         rt2->rt_hdr.segments_left = 1;
389         memset(&rt2->reserved, 0, sizeof(rt2->reserved));
390 
391         WARN_ON(rt2->rt_hdr.hdrlen != 2);
392 
393         memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
394         spin_lock_bh(&x->lock);
395         memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
396         spin_unlock_bh(&x->lock);
397 
398         return 0;
399 }
400 
401 static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
402                              u8 **nexthdr)
403 {
404         u16 offset = sizeof(struct ipv6hdr);
405         struct ipv6_opt_hdr *exthdr =
406                                    (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
407         const unsigned char *nh = skb_network_header(skb);
408         unsigned int packet_len = skb_tail_pointer(skb) -
409                 skb_network_header(skb);
410         int found_rhdr = 0;
411 
412         *nexthdr = &ipv6_hdr(skb)->nexthdr;
413 
414         while (offset + 1 <= packet_len) {
415 
416                 switch (**nexthdr) {
417                 case NEXTHDR_HOP:
418                         break;
419                 case NEXTHDR_ROUTING:
420                         if (offset + 3 <= packet_len) {
421                                 struct ipv6_rt_hdr *rt;
422                                 rt = (struct ipv6_rt_hdr *)(nh + offset);
423                                 if (rt->type != 0)
424                                         return offset;
425                         }
426                         found_rhdr = 1;
427                         break;
428                 case NEXTHDR_DEST:
429                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
430                                 return offset;
431 
432                         if (found_rhdr)
433                                 return offset;
434 
435                         break;
436                 default:
437                         return offset;
438                 }
439 
440                 offset += ipv6_optlen(exthdr);
441                 *nexthdr = &exthdr->nexthdr;
442                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
443         }
444 
445         return offset;
446 }
447 
448 static int mip6_rthdr_init_state(struct xfrm_state *x)
449 {
450         if (x->id.spi) {
451                 pr_info("%s: spi is not 0: %u\n", __func__, x->id.spi);
452                 return -EINVAL;
453         }
454         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
455                 pr_info("%s: state's mode is not %u: %u\n",
456                         __func__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
457                 return -EINVAL;
458         }
459 
460         x->props.header_len = sizeof(struct rt2_hdr);
461 
462         return 0;
463 }
464 
465 /*
466  * Do nothing about destroying since it has no specific operation for routing
467  * header type 2 unlike IPsec protocols.
468  */
469 static void mip6_rthdr_destroy(struct xfrm_state *x)
470 {
471 }
472 
473 static const struct xfrm_type mip6_rthdr_type =
474 {
475         .description    = "MIP6RT",
476         .owner          = THIS_MODULE,
477         .proto          = IPPROTO_ROUTING,
478         .flags          = XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_REMOTE_COADDR,
479         .init_state     = mip6_rthdr_init_state,
480         .destructor     = mip6_rthdr_destroy,
481         .input          = mip6_rthdr_input,
482         .output         = mip6_rthdr_output,
483         .hdr_offset     = mip6_rthdr_offset,
484 };
485 
486 static int __init mip6_init(void)
487 {
488         pr_info("Mobile IPv6\n");
489 
490         if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
491                 pr_info("%s: can't add xfrm type(destopt)\n", __func__);
492                 goto mip6_destopt_xfrm_fail;
493         }
494         if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
495                 pr_info("%s: can't add xfrm type(rthdr)\n", __func__);
496                 goto mip6_rthdr_xfrm_fail;
497         }
498         if (rawv6_mh_filter_register(mip6_mh_filter) < 0) {
499                 pr_info("%s: can't add rawv6 mh filter\n", __func__);
500                 goto mip6_rawv6_mh_fail;
501         }
502 
503 
504         return 0;
505 
506  mip6_rawv6_mh_fail:
507         xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
508  mip6_rthdr_xfrm_fail:
509         xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
510  mip6_destopt_xfrm_fail:
511         return -EAGAIN;
512 }
513 
514 static void __exit mip6_fini(void)
515 {
516         if (rawv6_mh_filter_unregister(mip6_mh_filter) < 0)
517                 pr_info("%s: can't remove rawv6 mh filter\n", __func__);
518         if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
519                 pr_info("%s: can't remove xfrm type(rthdr)\n", __func__);
520         if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
521                 pr_info("%s: can't remove xfrm type(destopt)\n", __func__);
522 }
523 
524 module_init(mip6_init);
525 module_exit(mip6_fini);
526 
527 MODULE_LICENSE("GPL");
528 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_DSTOPTS);
529 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ROUTING);
530 

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