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	ktime_t 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(ktime_t 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 (!ktime_equal(mip6_report_rl.stamp, stamp) ||
195	    mip6_report_rl.iif != iif ||
196	    !ipv6_addr_equal(&mip6_report_rl.src, src) ||
197	    !ipv6_addr_equal(&mip6_report_rl.dst, dst)) {
198		mip6_report_rl.stamp = stamp;
199		mip6_report_rl.iif = iif;
200		mip6_report_rl.src = *src;
201		mip6_report_rl.dst = *dst;
202		allow = 1;
203	}
204	spin_unlock_bh(&mip6_report_rl.lock);
205	return allow;
206}
207
208static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb,
209			       const struct flowi *fl)
210{
211	struct net *net = xs_net(x);
212	struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
213	const struct flowi6 *fl6 = &fl->u.ip6;
214	struct ipv6_destopt_hao *hao = NULL;
215	struct xfrm_selector sel;
216	int offset;
217	ktime_t stamp;
218	int err = 0;
219
220	if (unlikely(fl6->flowi6_proto == IPPROTO_MH &&
221		     fl6->fl6_mh_type <= IP6_MH_TYPE_MAX))
222		goto out;
223
224	if (likely(opt->dsthao)) {
225		offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
226		if (likely(offset >= 0))
227			hao = (struct ipv6_destopt_hao *)
228					(skb_network_header(skb) + offset);
229	}
230
231	stamp = skb_get_ktime(skb);
232
233	if (!mip6_report_rl_allow(stamp, &ipv6_hdr(skb)->daddr,
234				  hao ? &hao->addr : &ipv6_hdr(skb)->saddr,
235				  opt->iif))
236		goto out;
237
238	memset(&sel, 0, sizeof(sel));
239	memcpy(&sel.daddr, (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
240	       sizeof(sel.daddr));
241	sel.prefixlen_d = 128;
242	memcpy(&sel.saddr, (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
243	       sizeof(sel.saddr));
244	sel.prefixlen_s = 128;
245	sel.family = AF_INET6;
246	sel.proto = fl6->flowi6_proto;
247	sel.dport = xfrm_flowi_dport(fl, &fl6->uli);
248	if (sel.dport)
249		sel.dport_mask = htons(~0);
250	sel.sport = xfrm_flowi_sport(fl, &fl6->uli);
251	if (sel.sport)
252		sel.sport_mask = htons(~0);
253	sel.ifindex = fl6->flowi6_oif;
254
255	err = km_report(net, IPPROTO_DSTOPTS, &sel,
256			(hao ? (xfrm_address_t *)&hao->addr : NULL));
257
258 out:
259	return err;
260}
261
262static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
263			       u8 **nexthdr)
264{
265	u16 offset = sizeof(struct ipv6hdr);
266	struct ipv6_opt_hdr *exthdr =
267				   (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
268	const unsigned char *nh = skb_network_header(skb);
269	unsigned int packet_len = skb_tail_pointer(skb) -
270		skb_network_header(skb);
271	int found_rhdr = 0;
272
273	*nexthdr = &ipv6_hdr(skb)->nexthdr;
274
275	while (offset + 1 <= packet_len) {
276
277		switch (**nexthdr) {
278		case NEXTHDR_HOP:
279			break;
280		case NEXTHDR_ROUTING:
281			found_rhdr = 1;
282			break;
283		case NEXTHDR_DEST:
284			/*
285			 * HAO MUST NOT appear more than once.
286			 * XXX: It is better to try to find by the end of
287			 * XXX: packet if HAO exists.
288			 */
289			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
290				net_dbg_ratelimited("mip6: hao exists already, override\n");
291				return offset;
292			}
293
294			if (found_rhdr)
295				return offset;
296
297			break;
298		default:
299			return offset;
300		}
301
302		offset += ipv6_optlen(exthdr);
303		*nexthdr = &exthdr->nexthdr;
304		exthdr = (struct ipv6_opt_hdr *)(nh + offset);
305	}
306
307	return offset;
308}
309
310static int mip6_destopt_init_state(struct xfrm_state *x)
311{
312	if (x->id.spi) {
313		pr_info("%s: spi is not 0: %u\n", __func__, x->id.spi);
314		return -EINVAL;
315	}
316	if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
317		pr_info("%s: state's mode is not %u: %u\n",
318			__func__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
319		return -EINVAL;
320	}
321
322	x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
323		calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
324		sizeof(struct ipv6_destopt_hao);
325	WARN_ON(x->props.header_len != 24);
326
327	return 0;
328}
329
330/*
331 * Do nothing about destroying since it has no specific operation for
332 * destination options header unlike IPsec protocols.
333 */
334static void mip6_destopt_destroy(struct xfrm_state *x)
335{
336}
337
338static const struct xfrm_type mip6_destopt_type = {
339	.description	= "MIP6DESTOPT",
340	.owner		= THIS_MODULE,
341	.proto		= IPPROTO_DSTOPTS,
342	.flags		= XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_LOCAL_COADDR,
343	.init_state	= mip6_destopt_init_state,
344	.destructor	= mip6_destopt_destroy,
345	.input		= mip6_destopt_input,
346	.output		= mip6_destopt_output,
347	.reject		= mip6_destopt_reject,
348	.hdr_offset	= mip6_destopt_offset,
349};
350
351static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
352{
353	const struct ipv6hdr *iph = ipv6_hdr(skb);
354	struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
355	int err = rt2->rt_hdr.nexthdr;
356
357	spin_lock(&x->lock);
358	if (!ipv6_addr_equal(&iph->daddr, (struct in6_addr *)x->coaddr) &&
359	    !ipv6_addr_any((struct in6_addr *)x->coaddr))
360		err = -ENOENT;
361	spin_unlock(&x->lock);
362
363	return err;
364}
365
366/* Routing Header type 2 is inserted.
367 * IP Header's dst address is replaced with Routing Header's Home Address.
368 */
369static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
370{
371	struct ipv6hdr *iph;
372	struct rt2_hdr *rt2;
373	u8 nexthdr;
374
375	skb_push(skb, -skb_network_offset(skb));
376	iph = ipv6_hdr(skb);
377
378	nexthdr = *skb_mac_header(skb);
379	*skb_mac_header(skb) = IPPROTO_ROUTING;
380
381	rt2 = (struct rt2_hdr *)skb_transport_header(skb);
382	rt2->rt_hdr.nexthdr = nexthdr;
383	rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
384	rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
385	rt2->rt_hdr.segments_left = 1;
386	memset(&rt2->reserved, 0, sizeof(rt2->reserved));
387
388	WARN_ON(rt2->rt_hdr.hdrlen != 2);
389
390	memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
391	spin_lock_bh(&x->lock);
392	memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
393	spin_unlock_bh(&x->lock);
394
395	return 0;
396}
397
398static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
399			     u8 **nexthdr)
400{
401	u16 offset = sizeof(struct ipv6hdr);
402	struct ipv6_opt_hdr *exthdr =
403				   (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
404	const unsigned char *nh = skb_network_header(skb);
405	unsigned int packet_len = skb_tail_pointer(skb) -
406		skb_network_header(skb);
407	int found_rhdr = 0;
408
409	*nexthdr = &ipv6_hdr(skb)->nexthdr;
410
411	while (offset + 1 <= packet_len) {
412
413		switch (**nexthdr) {
414		case NEXTHDR_HOP:
415			break;
416		case NEXTHDR_ROUTING:
417			if (offset + 3 <= packet_len) {
418				struct ipv6_rt_hdr *rt;
419				rt = (struct ipv6_rt_hdr *)(nh + offset);
420				if (rt->type != 0)
421					return offset;
422			}
423			found_rhdr = 1;
424			break;
425		case NEXTHDR_DEST:
426			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
427				return offset;
428
429			if (found_rhdr)
430				return offset;
431
432			break;
433		default:
434			return offset;
435		}
436
437		offset += ipv6_optlen(exthdr);
438		*nexthdr = &exthdr->nexthdr;
439		exthdr = (struct ipv6_opt_hdr *)(nh + offset);
440	}
441
442	return offset;
443}
444
445static int mip6_rthdr_init_state(struct xfrm_state *x)
446{
447	if (x->id.spi) {
448		pr_info("%s: spi is not 0: %u\n", __func__, x->id.spi);
449		return -EINVAL;
450	}
451	if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
452		pr_info("%s: state's mode is not %u: %u\n",
453			__func__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
454		return -EINVAL;
455	}
456
457	x->props.header_len = sizeof(struct rt2_hdr);
458
459	return 0;
460}
461
462/*
463 * Do nothing about destroying since it has no specific operation for routing
464 * header type 2 unlike IPsec protocols.
465 */
466static void mip6_rthdr_destroy(struct xfrm_state *x)
467{
468}
469
470static const struct xfrm_type mip6_rthdr_type = {
471	.description	= "MIP6RT",
472	.owner		= THIS_MODULE,
473	.proto		= IPPROTO_ROUTING,
474	.flags		= XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_REMOTE_COADDR,
475	.init_state	= mip6_rthdr_init_state,
476	.destructor	= mip6_rthdr_destroy,
477	.input		= mip6_rthdr_input,
478	.output		= mip6_rthdr_output,
479	.hdr_offset	= mip6_rthdr_offset,
480};
481
482static int __init mip6_init(void)
483{
484	pr_info("Mobile IPv6\n");
485
486	if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
487		pr_info("%s: can't add xfrm type(destopt)\n", __func__);
488		goto mip6_destopt_xfrm_fail;
489	}
490	if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
491		pr_info("%s: can't add xfrm type(rthdr)\n", __func__);
492		goto mip6_rthdr_xfrm_fail;
493	}
494	if (rawv6_mh_filter_register(mip6_mh_filter) < 0) {
495		pr_info("%s: can't add rawv6 mh filter\n", __func__);
496		goto mip6_rawv6_mh_fail;
497	}
498
499
500	return 0;
501
502 mip6_rawv6_mh_fail:
503	xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
504 mip6_rthdr_xfrm_fail:
505	xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
506 mip6_destopt_xfrm_fail:
507	return -EAGAIN;
508}
509
510static void __exit mip6_fini(void)
511{
512	if (rawv6_mh_filter_unregister(mip6_mh_filter) < 0)
513		pr_info("%s: can't remove rawv6 mh filter\n", __func__);
514	if (xfrm_unregister_type(&mip6_rthdr_type, AF_INET6) < 0)
515		pr_info("%s: can't remove xfrm type(rthdr)\n", __func__);
516	if (xfrm_unregister_type(&mip6_destopt_type, AF_INET6) < 0)
517		pr_info("%s: can't remove xfrm type(destopt)\n", __func__);
518}
519
520module_init(mip6_init);
521module_exit(mip6_fini);
522
523MODULE_LICENSE("GPL");
524MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_DSTOPTS);
525MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ROUTING);
526