xref: /openbmc/linux/net/ipv6/mip6.c (revision e23feb16) 
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