xref: /openbmc/linux/net/ipv6/mip6.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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/xfrm.h>
34 #include <net/mip6.h>
35 
36 static xfrm_address_t *mip6_xfrm_addr(struct xfrm_state *x, xfrm_address_t *addr)
37 {
38 	return x->coaddr;
39 }
40 
41 static inline unsigned int calc_padlen(unsigned int len, unsigned int n)
42 {
43 	return (n - len + 16) & 0x7;
44 }
45 
46 static inline void *mip6_padn(__u8 *data, __u8 padlen)
47 {
48 	if (!data)
49 		return NULL;
50 	if (padlen == 1) {
51 		data[0] = MIP6_OPT_PAD_1;
52 	} else if (padlen > 1) {
53 		data[0] = MIP6_OPT_PAD_N;
54 		data[1] = padlen - 2;
55 		if (padlen > 2)
56 			memset(data+2, 0, data[1]);
57 	}
58 	return data + padlen;
59 }
60 
61 static inline void mip6_param_prob(struct sk_buff *skb, int code, int pos)
62 {
63 	icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos, skb->dev);
64 }
65 
66 static int mip6_mh_len(int type)
67 {
68 	int len = 0;
69 
70 	switch (type) {
71 	case IP6_MH_TYPE_BRR:
72 		len = 0;
73 		break;
74 	case IP6_MH_TYPE_HOTI:
75 	case IP6_MH_TYPE_COTI:
76 	case IP6_MH_TYPE_BU:
77 	case IP6_MH_TYPE_BACK:
78 		len = 1;
79 		break;
80 	case IP6_MH_TYPE_HOT:
81 	case IP6_MH_TYPE_COT:
82 	case IP6_MH_TYPE_BERROR:
83 		len = 2;
84 		break;
85 	}
86 	return len;
87 }
88 
89 int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
90 {
91 	struct ip6_mh *mh;
92 
93 	if (!pskb_may_pull(skb, (skb_transport_offset(skb)) + 8) ||
94 	    !pskb_may_pull(skb, (skb_transport_offset(skb) +
95 				 ((skb_transport_header(skb)[1] + 1) << 3))))
96 		return -1;
97 
98 	mh = (struct ip6_mh *)skb_transport_header(skb);
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, ((&mh->ip6mh_hdrlen) -
104 					 skb_network_header(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, ((&mh->ip6mh_proto) -
112 					 skb_network_header(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 	struct ipv6hdr *iph = ipv6_hdr(skb);
134 	struct ipv6_destopt_hdr *destopt = (struct ipv6_destopt_hdr *)skb->data;
135 
136 	if (!ipv6_addr_equal(&iph->saddr, (struct in6_addr *)x->coaddr) &&
137 	    !ipv6_addr_any((struct in6_addr *)x->coaddr))
138 		return -ENOENT;
139 
140 	return destopt->nexthdr;
141 }
142 
143 /* Destination Option Header is inserted.
144  * IP Header's src address is replaced with Home Address Option in
145  * Destination Option Header.
146  */
147 static int mip6_destopt_output(struct xfrm_state *x, struct sk_buff *skb)
148 {
149 	struct ipv6hdr *iph;
150 	struct ipv6_destopt_hdr *dstopt;
151 	struct ipv6_destopt_hao *hao;
152 	u8 nexthdr;
153 	int len;
154 
155 	iph = (struct ipv6hdr *)skb->data;
156 	iph->payload_len = htons(skb->len - sizeof(*iph));
157 
158 	nexthdr = *skb_network_header(skb);
159 	*skb_network_header(skb) = IPPROTO_DSTOPTS;
160 
161 	dstopt = (struct ipv6_destopt_hdr *)skb_transport_header(skb);
162 	dstopt->nexthdr = nexthdr;
163 
164 	hao = mip6_padn((char *)(dstopt + 1),
165 			calc_padlen(sizeof(*dstopt), 6));
166 
167 	hao->type = IPV6_TLV_HAO;
168 	hao->length = sizeof(*hao) - 2;
169 	BUG_TRAP(hao->length == 16);
170 
171 	len = ((char *)hao - (char *)dstopt) + sizeof(*hao);
172 
173 	memcpy(&hao->addr, &iph->saddr, sizeof(hao->addr));
174 	memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
175 
176 	BUG_TRAP(len == x->props.header_len);
177 	dstopt->hdrlen = (x->props.header_len >> 3) - 1;
178 
179 	return 0;
180 }
181 
182 static inline int mip6_report_rl_allow(struct timeval *stamp,
183 				       struct in6_addr *dst,
184 				       struct in6_addr *src, int iif)
185 {
186 	int allow = 0;
187 
188 	spin_lock_bh(&mip6_report_rl.lock);
189 	if (mip6_report_rl.stamp.tv_sec != stamp->tv_sec ||
190 	    mip6_report_rl.stamp.tv_usec != stamp->tv_usec ||
191 	    mip6_report_rl.iif != iif ||
192 	    !ipv6_addr_equal(&mip6_report_rl.src, src) ||
193 	    !ipv6_addr_equal(&mip6_report_rl.dst, dst)) {
194 		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_copy(&mip6_report_rl.src, src);
198 		ipv6_addr_copy(&mip6_report_rl.dst, dst);
199 		allow = 1;
200 	}
201 	spin_unlock_bh(&mip6_report_rl.lock);
202 	return allow;
203 }
204 
205 static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb, struct flowi *fl)
206 {
207 	struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
208 	struct ipv6_destopt_hao *hao = NULL;
209 	struct xfrm_selector sel;
210 	int offset;
211 	struct timeval stamp;
212 	int err = 0;
213 
214 	if (unlikely(fl->proto == IPPROTO_MH &&
215 		     fl->fl_mh_type <= IP6_MH_TYPE_MAX))
216 		goto out;
217 
218 	if (likely(opt->dsthao)) {
219 		offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
220 		if (likely(offset >= 0))
221 			hao = (struct ipv6_destopt_hao *)
222 					(skb_network_header(skb) + offset);
223 	}
224 
225 	skb_get_timestamp(skb, &stamp);
226 
227 	if (!mip6_report_rl_allow(&stamp, &ipv6_hdr(skb)->daddr,
228 				  hao ? &hao->addr : &ipv6_hdr(skb)->saddr,
229 				  opt->iif))
230 		goto out;
231 
232 	memset(&sel, 0, sizeof(sel));
233 	memcpy(&sel.daddr, (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
234 	       sizeof(sel.daddr));
235 	sel.prefixlen_d = 128;
236 	memcpy(&sel.saddr, (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
237 	       sizeof(sel.saddr));
238 	sel.prefixlen_s = 128;
239 	sel.family = AF_INET6;
240 	sel.proto = fl->proto;
241 	sel.dport = xfrm_flowi_dport(fl);
242 	if (sel.dport)
243 		sel.dport_mask = htons(~0);
244 	sel.sport = xfrm_flowi_sport(fl);
245 	if (sel.sport)
246 		sel.sport_mask = htons(~0);
247 	sel.ifindex = fl->oif;
248 
249 	err = km_report(IPPROTO_DSTOPTS, &sel,
250 			(hao ? (xfrm_address_t *)&hao->addr : NULL));
251 
252  out:
253 	return err;
254 }
255 
256 static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
257 			       u8 **nexthdr)
258 {
259 	u16 offset = sizeof(struct ipv6hdr);
260 	struct ipv6_opt_hdr *exthdr =
261 				   (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
262 	const unsigned char *nh = skb_network_header(skb);
263 	unsigned int packet_len = skb->tail - skb->network_header;
264 	int found_rhdr = 0;
265 
266 	*nexthdr = &ipv6_hdr(skb)->nexthdr;
267 
268 	while (offset + 1 <= packet_len) {
269 
270 		switch (**nexthdr) {
271 		case NEXTHDR_HOP:
272 			break;
273 		case NEXTHDR_ROUTING:
274 			found_rhdr = 1;
275 			break;
276 		case NEXTHDR_DEST:
277 			/*
278 			 * HAO MUST NOT appear more than once.
279 			 * XXX: It is better to try to find by the end of
280 			 * XXX: packet if HAO exists.
281 			 */
282 			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
283 				LIMIT_NETDEBUG(KERN_WARNING "mip6: hao exists already, override\n");
284 				return offset;
285 			}
286 
287 			if (found_rhdr)
288 				return offset;
289 
290 			break;
291 		default:
292 			return offset;
293 		}
294 
295 		offset += ipv6_optlen(exthdr);
296 		*nexthdr = &exthdr->nexthdr;
297 		exthdr = (struct ipv6_opt_hdr *)(nh + offset);
298 	}
299 
300 	return offset;
301 }
302 
303 static int mip6_destopt_init_state(struct xfrm_state *x)
304 {
305 	if (x->id.spi) {
306 		printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
307 		       x->id.spi);
308 		return -EINVAL;
309 	}
310 	if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
311 		printk(KERN_INFO "%s: state's mode is not %u: %u\n",
312 		       __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
313 		return -EINVAL;
314 	}
315 
316 	x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
317 		calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
318 		sizeof(struct ipv6_destopt_hao);
319 	BUG_TRAP(x->props.header_len == 24);
320 
321 	return 0;
322 }
323 
324 /*
325  * Do nothing about destroying since it has no specific operation for
326  * destination options header unlike IPsec protocols.
327  */
328 static void mip6_destopt_destroy(struct xfrm_state *x)
329 {
330 }
331 
332 static struct xfrm_type mip6_destopt_type =
333 {
334 	.description	= "MIP6DESTOPT",
335 	.owner		= THIS_MODULE,
336 	.proto	     	= IPPROTO_DSTOPTS,
337 	.flags		= XFRM_TYPE_NON_FRAGMENT,
338 	.init_state	= mip6_destopt_init_state,
339 	.destructor	= mip6_destopt_destroy,
340 	.input		= mip6_destopt_input,
341 	.output		= mip6_destopt_output,
342 	.reject		= mip6_destopt_reject,
343 	.hdr_offset	= mip6_destopt_offset,
344 	.local_addr	= mip6_xfrm_addr,
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 
351 	if (!ipv6_addr_equal(&rt2->addr, (struct in6_addr *)x->coaddr) &&
352 	    !ipv6_addr_any((struct in6_addr *)x->coaddr))
353 		return -ENOENT;
354 
355 	return rt2->rt_hdr.nexthdr;
356 }
357 
358 /* Routing Header type 2 is inserted.
359  * IP Header's dst address is replaced with Routing Header's Home Address.
360  */
361 static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
362 {
363 	struct ipv6hdr *iph;
364 	struct rt2_hdr *rt2;
365 	u8 nexthdr;
366 
367 	iph = (struct ipv6hdr *)skb->data;
368 	iph->payload_len = htons(skb->len - sizeof(*iph));
369 
370 	nexthdr = *skb_network_header(skb);
371 	*skb_network_header(skb) = IPPROTO_ROUTING;
372 
373 	rt2 = (struct rt2_hdr *)skb_transport_header(skb);
374 	rt2->rt_hdr.nexthdr = nexthdr;
375 	rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
376 	rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
377 	rt2->rt_hdr.segments_left = 1;
378 	memset(&rt2->reserved, 0, sizeof(rt2->reserved));
379 
380 	BUG_TRAP(rt2->rt_hdr.hdrlen == 2);
381 
382 	memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
383 	memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
384 
385 	return 0;
386 }
387 
388 static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
389 			     u8 **nexthdr)
390 {
391 	u16 offset = sizeof(struct ipv6hdr);
392 	struct ipv6_opt_hdr *exthdr =
393 				   (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
394 	const unsigned char *nh = skb_network_header(skb);
395 	unsigned int packet_len = skb->tail - skb->network_header;
396 	int found_rhdr = 0;
397 
398 	*nexthdr = &ipv6_hdr(skb)->nexthdr;
399 
400 	while (offset + 1 <= packet_len) {
401 
402 		switch (**nexthdr) {
403 		case NEXTHDR_HOP:
404 			break;
405 		case NEXTHDR_ROUTING:
406 			if (offset + 3 <= packet_len) {
407 				struct ipv6_rt_hdr *rt;
408 				rt = (struct ipv6_rt_hdr *)(nh + offset);
409 				if (rt->type != 0)
410 					return offset;
411 			}
412 			found_rhdr = 1;
413 			break;
414 		case NEXTHDR_DEST:
415 			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
416 				return offset;
417 
418 			if (found_rhdr)
419 				return offset;
420 
421 			break;
422 		default:
423 			return offset;
424 		}
425 
426 		offset += ipv6_optlen(exthdr);
427 		*nexthdr = &exthdr->nexthdr;
428 		exthdr = (struct ipv6_opt_hdr *)(nh + offset);
429 	}
430 
431 	return offset;
432 }
433 
434 static int mip6_rthdr_init_state(struct xfrm_state *x)
435 {
436 	if (x->id.spi) {
437 		printk(KERN_INFO "%s: spi is not 0: %u\n", __FUNCTION__,
438 		       x->id.spi);
439 		return -EINVAL;
440 	}
441 	if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
442 		printk(KERN_INFO "%s: state's mode is not %u: %u\n",
443 		       __FUNCTION__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
444 		return -EINVAL;
445 	}
446 
447 	x->props.header_len = sizeof(struct rt2_hdr);
448 
449 	return 0;
450 }
451 
452 /*
453  * Do nothing about destroying since it has no specific operation for routing
454  * header type 2 unlike IPsec protocols.
455  */
456 static void mip6_rthdr_destroy(struct xfrm_state *x)
457 {
458 }
459 
460 static struct xfrm_type mip6_rthdr_type =
461 {
462 	.description	= "MIP6RT",
463 	.owner		= THIS_MODULE,
464 	.proto	     	= IPPROTO_ROUTING,
465 	.flags		= XFRM_TYPE_NON_FRAGMENT,
466 	.init_state	= mip6_rthdr_init_state,
467 	.destructor	= mip6_rthdr_destroy,
468 	.input		= mip6_rthdr_input,
469 	.output		= mip6_rthdr_output,
470 	.hdr_offset	= mip6_rthdr_offset,
471 	.remote_addr	= mip6_xfrm_addr,
472 };
473 
474 int __init mip6_init(void)
475 {
476 	printk(KERN_INFO "Mobile IPv6\n");
477 
478 	if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
479 		printk(KERN_INFO "%s: can't add xfrm type(destopt)\n", __FUNCTION__);
480 		goto mip6_destopt_xfrm_fail;
481 	}
482 	if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
483 		printk(KERN_INFO "%s: can't add xfrm type(rthdr)\n", __FUNCTION__);
484 		goto mip6_rthdr_xfrm_fail;
485 	}
486 	return 0;
487 
488  mip6_rthdr_xfrm_fail:
489 	xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
490  mip6_destopt_xfrm_fail:
491 	return -EAGAIN;
492 }
493 
494 void __exit mip6_fini(void)
495 {
496 	if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
497 		printk(KERN_INFO "%s: can't remove xfrm type(rthdr)\n", __FUNCTION__);
498 	if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
499 		printk(KERN_INFO "%s: can't remove xfrm type(destopt)\n", __FUNCTION__);
500 }
501