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, see <http://www.gnu.org/licenses/>.
17 */
18/*
19 * Authors:
20 *	Noriaki TAKAMIYA @USAGI
21 *	Masahide NAKAMURA @USAGI
22 */
23
24#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
25
26#include <linux/module.h>
27#include <linux/skbuff.h>
28#include <linux/time.h>
29#include <linux/ipv6.h>
30#include <linux/icmpv6.h>
31#include <net/sock.h>
32#include <net/ipv6.h>
33#include <net/ip6_checksum.h>
34#include <net/rawv6.h>
35#include <net/xfrm.h>
36#include <net/mip6.h>
37
38static inline unsigned int calc_padlen(unsigned int len, unsigned int n)
39{
40	return (n - len + 16) & 0x7;
41}
42
43static inline void *mip6_padn(__u8 *data, __u8 padlen)
44{
45	if (!data)
46		return NULL;
47	if (padlen == 1) {
48		data[0] = IPV6_TLV_PAD1;
49	} else if (padlen > 1) {
50		data[0] = IPV6_TLV_PADN;
51		data[1] = padlen - 2;
52		if (padlen > 2)
53			memset(data+2, 0, data[1]);
54	}
55	return data + padlen;
56}
57
58static inline void mip6_param_prob(struct sk_buff *skb, u8 code, int pos)
59{
60	icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos);
61}
62
63static int mip6_mh_len(int type)
64{
65	int len = 0;
66
67	switch (type) {
68	case IP6_MH_TYPE_BRR:
69		len = 0;
70		break;
71	case IP6_MH_TYPE_HOTI:
72	case IP6_MH_TYPE_COTI:
73	case IP6_MH_TYPE_BU:
74	case IP6_MH_TYPE_BACK:
75		len = 1;
76		break;
77	case IP6_MH_TYPE_HOT:
78	case IP6_MH_TYPE_COT:
79	case IP6_MH_TYPE_BERROR:
80		len = 2;
81		break;
82	}
83	return len;
84}
85
86static int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
87{
88	struct ip6_mh _hdr;
89	const struct ip6_mh *mh;
90
91	mh = skb_header_pointer(skb, skb_transport_offset(skb),
92				sizeof(_hdr), &_hdr);
93	if (!mh)
94		return -1;
95
96	if (((mh->ip6mh_hdrlen + 1) << 3) > skb->len)
97		return -1;
98
99	if (mh->ip6mh_hdrlen < mip6_mh_len(mh->ip6mh_type)) {
100		net_dbg_ratelimited("mip6: MH message too short: %d vs >=%d\n",
101				    mh->ip6mh_hdrlen,
102				    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		net_dbg_ratelimited("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
119struct 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
127static struct mip6_report_rate_limiter mip6_report_rl = {
128	.lock = __SPIN_LOCK_UNLOCKED(mip6_report_rl.lock)
129};
130
131static 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 */
150static 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
187static 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
210static 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
264static 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				net_dbg_ratelimited("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
312static 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 */
336static void mip6_destopt_destroy(struct xfrm_state *x)
337{
338}
339
340static const struct xfrm_type mip6_destopt_type = {
341	.description	= "MIP6DESTOPT",
342	.owner		= THIS_MODULE,
343	.proto		= IPPROTO_DSTOPTS,
344	.flags		= XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_LOCAL_COADDR,
345	.init_state	= mip6_destopt_init_state,
346	.destructor	= mip6_destopt_destroy,
347	.input		= mip6_destopt_input,
348	.output		= mip6_destopt_output,
349	.reject		= mip6_destopt_reject,
350	.hdr_offset	= mip6_destopt_offset,
351};
352
353static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
354{
355	const struct ipv6hdr *iph = ipv6_hdr(skb);
356	struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
357	int err = rt2->rt_hdr.nexthdr;
358
359	spin_lock(&x->lock);
360	if (!ipv6_addr_equal(&iph->daddr, (struct in6_addr *)x->coaddr) &&
361	    !ipv6_addr_any((struct in6_addr *)x->coaddr))
362		err = -ENOENT;
363	spin_unlock(&x->lock);
364
365	return err;
366}
367
368/* Routing Header type 2 is inserted.
369 * IP Header's dst address is replaced with Routing Header's Home Address.
370 */
371static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
372{
373	struct ipv6hdr *iph;
374	struct rt2_hdr *rt2;
375	u8 nexthdr;
376
377	skb_push(skb, -skb_network_offset(skb));
378	iph = ipv6_hdr(skb);
379
380	nexthdr = *skb_mac_header(skb);
381	*skb_mac_header(skb) = IPPROTO_ROUTING;
382
383	rt2 = (struct rt2_hdr *)skb_transport_header(skb);
384	rt2->rt_hdr.nexthdr = nexthdr;
385	rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
386	rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
387	rt2->rt_hdr.segments_left = 1;
388	memset(&rt2->reserved, 0, sizeof(rt2->reserved));
389
390	WARN_ON(rt2->rt_hdr.hdrlen != 2);
391
392	memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
393	spin_lock_bh(&x->lock);
394	memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
395	spin_unlock_bh(&x->lock);
396
397	return 0;
398}
399
400static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
401			     u8 **nexthdr)
402{
403	u16 offset = sizeof(struct ipv6hdr);
404	struct ipv6_opt_hdr *exthdr =
405				   (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
406	const unsigned char *nh = skb_network_header(skb);
407	unsigned int packet_len = skb_tail_pointer(skb) -
408		skb_network_header(skb);
409	int found_rhdr = 0;
410
411	*nexthdr = &ipv6_hdr(skb)->nexthdr;
412
413	while (offset + 1 <= packet_len) {
414
415		switch (**nexthdr) {
416		case NEXTHDR_HOP:
417			break;
418		case NEXTHDR_ROUTING:
419			if (offset + 3 <= packet_len) {
420				struct ipv6_rt_hdr *rt;
421				rt = (struct ipv6_rt_hdr *)(nh + offset);
422				if (rt->type != 0)
423					return offset;
424			}
425			found_rhdr = 1;
426			break;
427		case NEXTHDR_DEST:
428			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
429				return offset;
430
431			if (found_rhdr)
432				return offset;
433
434			break;
435		default:
436			return offset;
437		}
438
439		offset += ipv6_optlen(exthdr);
440		*nexthdr = &exthdr->nexthdr;
441		exthdr = (struct ipv6_opt_hdr *)(nh + offset);
442	}
443
444	return offset;
445}
446
447static int mip6_rthdr_init_state(struct xfrm_state *x)
448{
449	if (x->id.spi) {
450		pr_info("%s: spi is not 0: %u\n", __func__, x->id.spi);
451		return -EINVAL;
452	}
453	if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
454		pr_info("%s: state's mode is not %u: %u\n",
455			__func__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
456		return -EINVAL;
457	}
458
459	x->props.header_len = sizeof(struct rt2_hdr);
460
461	return 0;
462}
463
464/*
465 * Do nothing about destroying since it has no specific operation for routing
466 * header type 2 unlike IPsec protocols.
467 */
468static void mip6_rthdr_destroy(struct xfrm_state *x)
469{
470}
471
472static const struct xfrm_type mip6_rthdr_type = {
473	.description	= "MIP6RT",
474	.owner		= THIS_MODULE,
475	.proto		= IPPROTO_ROUTING,
476	.flags		= XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_REMOTE_COADDR,
477	.init_state	= mip6_rthdr_init_state,
478	.destructor	= mip6_rthdr_destroy,
479	.input		= mip6_rthdr_input,
480	.output		= mip6_rthdr_output,
481	.hdr_offset	= mip6_rthdr_offset,
482};
483
484static int __init mip6_init(void)
485{
486	pr_info("Mobile IPv6\n");
487
488	if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
489		pr_info("%s: can't add xfrm type(destopt)\n", __func__);
490		goto mip6_destopt_xfrm_fail;
491	}
492	if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
493		pr_info("%s: can't add xfrm type(rthdr)\n", __func__);
494		goto mip6_rthdr_xfrm_fail;
495	}
496	if (rawv6_mh_filter_register(mip6_mh_filter) < 0) {
497		pr_info("%s: can't add rawv6 mh filter\n", __func__);
498		goto mip6_rawv6_mh_fail;
499	}
500
501
502	return 0;
503
504 mip6_rawv6_mh_fail:
505	xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
506 mip6_rthdr_xfrm_fail:
507	xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
508 mip6_destopt_xfrm_fail:
509	return -EAGAIN;
510}
511
512static void __exit mip6_fini(void)
513{
514	if (rawv6_mh_filter_unregister(mip6_mh_filter) < 0)
515		pr_info("%s: can't remove rawv6 mh filter\n", __func__);
516	if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
517		pr_info("%s: can't remove xfrm type(rthdr)\n", __func__);
518	if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
519		pr_info("%s: can't remove xfrm type(destopt)\n", __func__);
520}
521
522module_init(mip6_init);
523module_exit(mip6_fini);
524
525MODULE_LICENSE("GPL");
526MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_DSTOPTS);
527MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ROUTING);
528