xref: /openbmc/linux/net/ipv6/mip6.c (revision 28b5dbd5)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright (C)2003-2006 Helsinki University of Technology
4  * Copyright (C)2003-2006 USAGI/WIDE Project
5  */
6 /*
7  * Authors:
8  *	Noriaki TAKAMIYA @USAGI
9  *	Masahide NAKAMURA @USAGI
10  */
11 
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 
14 #include <linux/module.h>
15 #include <linux/skbuff.h>
16 #include <linux/time.h>
17 #include <linux/ipv6.h>
18 #include <linux/icmpv6.h>
19 #include <net/sock.h>
20 #include <net/ipv6.h>
21 #include <net/ip6_checksum.h>
22 #include <net/rawv6.h>
23 #include <net/xfrm.h>
24 #include <net/mip6.h>
25 
calc_padlen(unsigned int len,unsigned int n)26 static inline unsigned int calc_padlen(unsigned int len, unsigned int n)
27 {
28 	return (n - len + 16) & 0x7;
29 }
30 
mip6_padn(__u8 * data,__u8 padlen)31 static inline void *mip6_padn(__u8 *data, __u8 padlen)
32 {
33 	if (!data)
34 		return NULL;
35 	if (padlen == 1) {
36 		data[0] = IPV6_TLV_PAD1;
37 	} else if (padlen > 1) {
38 		data[0] = IPV6_TLV_PADN;
39 		data[1] = padlen - 2;
40 		if (padlen > 2)
41 			memset(data+2, 0, data[1]);
42 	}
43 	return data + padlen;
44 }
45 
mip6_param_prob(struct sk_buff * skb,u8 code,int pos)46 static inline void mip6_param_prob(struct sk_buff *skb, u8 code, int pos)
47 {
48 	icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos);
49 }
50 
mip6_mh_len(int type)51 static int mip6_mh_len(int type)
52 {
53 	int len = 0;
54 
55 	switch (type) {
56 	case IP6_MH_TYPE_BRR:
57 		len = 0;
58 		break;
59 	case IP6_MH_TYPE_HOTI:
60 	case IP6_MH_TYPE_COTI:
61 	case IP6_MH_TYPE_BU:
62 	case IP6_MH_TYPE_BACK:
63 		len = 1;
64 		break;
65 	case IP6_MH_TYPE_HOT:
66 	case IP6_MH_TYPE_COT:
67 	case IP6_MH_TYPE_BERROR:
68 		len = 2;
69 		break;
70 	}
71 	return len;
72 }
73 
mip6_mh_filter(struct sock * sk,struct sk_buff * skb)74 static int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
75 {
76 	struct ip6_mh _hdr;
77 	const struct ip6_mh *mh;
78 
79 	mh = skb_header_pointer(skb, skb_transport_offset(skb),
80 				sizeof(_hdr), &_hdr);
81 	if (!mh)
82 		return -1;
83 
84 	if (((mh->ip6mh_hdrlen + 1) << 3) > skb->len)
85 		return -1;
86 
87 	if (mh->ip6mh_hdrlen < mip6_mh_len(mh->ip6mh_type)) {
88 		net_dbg_ratelimited("mip6: MH message too short: %d vs >=%d\n",
89 				    mh->ip6mh_hdrlen,
90 				    mip6_mh_len(mh->ip6mh_type));
91 		mip6_param_prob(skb, 0, offsetof(struct ip6_mh, ip6mh_hdrlen) +
92 				skb_network_header_len(skb));
93 		return -1;
94 	}
95 
96 	if (mh->ip6mh_proto != IPPROTO_NONE) {
97 		net_dbg_ratelimited("mip6: MH invalid payload proto = %d\n",
98 				    mh->ip6mh_proto);
99 		mip6_param_prob(skb, 0, offsetof(struct ip6_mh, ip6mh_proto) +
100 				skb_network_header_len(skb));
101 		return -1;
102 	}
103 
104 	return 0;
105 }
106 
107 struct mip6_report_rate_limiter {
108 	spinlock_t lock;
109 	ktime_t stamp;
110 	int iif;
111 	struct in6_addr src;
112 	struct in6_addr dst;
113 };
114 
115 static struct mip6_report_rate_limiter mip6_report_rl = {
116 	.lock = __SPIN_LOCK_UNLOCKED(mip6_report_rl.lock)
117 };
118 
mip6_destopt_input(struct xfrm_state * x,struct sk_buff * skb)119 static int mip6_destopt_input(struct xfrm_state *x, struct sk_buff *skb)
120 {
121 	const struct ipv6hdr *iph = ipv6_hdr(skb);
122 	struct ipv6_destopt_hdr *destopt = (struct ipv6_destopt_hdr *)skb->data;
123 	int err = destopt->nexthdr;
124 
125 	spin_lock(&x->lock);
126 	if (!ipv6_addr_equal(&iph->saddr, (struct in6_addr *)x->coaddr) &&
127 	    !ipv6_addr_any((struct in6_addr *)x->coaddr))
128 		err = -ENOENT;
129 	spin_unlock(&x->lock);
130 
131 	return err;
132 }
133 
134 /* Destination Option Header is inserted.
135  * IP Header's src address is replaced with Home Address Option in
136  * Destination Option Header.
137  */
mip6_destopt_output(struct xfrm_state * x,struct sk_buff * skb)138 static int mip6_destopt_output(struct xfrm_state *x, struct sk_buff *skb)
139 {
140 	struct ipv6hdr *iph;
141 	struct ipv6_destopt_hdr *dstopt;
142 	struct ipv6_destopt_hao *hao;
143 	u8 nexthdr;
144 	int len;
145 
146 	skb_push(skb, -skb_network_offset(skb));
147 	iph = ipv6_hdr(skb);
148 
149 	nexthdr = *skb_mac_header(skb);
150 	*skb_mac_header(skb) = IPPROTO_DSTOPTS;
151 
152 	dstopt = (struct ipv6_destopt_hdr *)skb_transport_header(skb);
153 	dstopt->nexthdr = nexthdr;
154 
155 	hao = mip6_padn((char *)(dstopt + 1),
156 			calc_padlen(sizeof(*dstopt), 6));
157 
158 	hao->type = IPV6_TLV_HAO;
159 	BUILD_BUG_ON(sizeof(*hao) != 18);
160 	hao->length = sizeof(*hao) - 2;
161 
162 	len = ((char *)hao - (char *)dstopt) + sizeof(*hao);
163 
164 	memcpy(&hao->addr, &iph->saddr, sizeof(hao->addr));
165 	spin_lock_bh(&x->lock);
166 	memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
167 	spin_unlock_bh(&x->lock);
168 
169 	WARN_ON(len != x->props.header_len);
170 	dstopt->hdrlen = (x->props.header_len >> 3) - 1;
171 
172 	return 0;
173 }
174 
mip6_report_rl_allow(ktime_t stamp,const struct in6_addr * dst,const struct in6_addr * src,int iif)175 static inline int mip6_report_rl_allow(ktime_t stamp,
176 				       const struct in6_addr *dst,
177 				       const struct in6_addr *src, int iif)
178 {
179 	int allow = 0;
180 
181 	spin_lock_bh(&mip6_report_rl.lock);
182 	if (mip6_report_rl.stamp != stamp ||
183 	    mip6_report_rl.iif != iif ||
184 	    !ipv6_addr_equal(&mip6_report_rl.src, src) ||
185 	    !ipv6_addr_equal(&mip6_report_rl.dst, dst)) {
186 		mip6_report_rl.stamp = stamp;
187 		mip6_report_rl.iif = iif;
188 		mip6_report_rl.src = *src;
189 		mip6_report_rl.dst = *dst;
190 		allow = 1;
191 	}
192 	spin_unlock_bh(&mip6_report_rl.lock);
193 	return allow;
194 }
195 
mip6_destopt_reject(struct xfrm_state * x,struct sk_buff * skb,const struct flowi * fl)196 static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb,
197 			       const struct flowi *fl)
198 {
199 	struct net *net = xs_net(x);
200 	struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
201 	const struct flowi6 *fl6 = &fl->u.ip6;
202 	struct ipv6_destopt_hao *hao = NULL;
203 	struct xfrm_selector sel;
204 	int offset;
205 	ktime_t stamp;
206 	int err = 0;
207 
208 	if (unlikely(fl6->flowi6_proto == IPPROTO_MH &&
209 		     fl6->fl6_mh_type <= IP6_MH_TYPE_MAX))
210 		goto out;
211 
212 	if (likely(opt->dsthao)) {
213 		offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
214 		if (likely(offset >= 0))
215 			hao = (struct ipv6_destopt_hao *)
216 					(skb_network_header(skb) + offset);
217 	}
218 
219 	stamp = skb_get_ktime(skb);
220 
221 	if (!mip6_report_rl_allow(stamp, &ipv6_hdr(skb)->daddr,
222 				  hao ? &hao->addr : &ipv6_hdr(skb)->saddr,
223 				  opt->iif))
224 		goto out;
225 
226 	memset(&sel, 0, sizeof(sel));
227 	memcpy(&sel.daddr, (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
228 	       sizeof(sel.daddr));
229 	sel.prefixlen_d = 128;
230 	memcpy(&sel.saddr, (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
231 	       sizeof(sel.saddr));
232 	sel.prefixlen_s = 128;
233 	sel.family = AF_INET6;
234 	sel.proto = fl6->flowi6_proto;
235 	sel.dport = xfrm_flowi_dport(fl, &fl6->uli);
236 	if (sel.dport)
237 		sel.dport_mask = htons(~0);
238 	sel.sport = xfrm_flowi_sport(fl, &fl6->uli);
239 	if (sel.sport)
240 		sel.sport_mask = htons(~0);
241 	sel.ifindex = fl6->flowi6_oif;
242 
243 	err = km_report(net, IPPROTO_DSTOPTS, &sel,
244 			(hao ? (xfrm_address_t *)&hao->addr : NULL));
245 
246  out:
247 	return err;
248 }
249 
mip6_destopt_init_state(struct xfrm_state * x,struct netlink_ext_ack * extack)250 static int mip6_destopt_init_state(struct xfrm_state *x, struct netlink_ext_ack *extack)
251 {
252 	if (x->id.spi) {
253 		NL_SET_ERR_MSG(extack, "SPI must be 0");
254 		return -EINVAL;
255 	}
256 	if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
257 		NL_SET_ERR_MSG(extack, "XFRM mode must be XFRM_MODE_ROUTEOPTIMIZATION");
258 		return -EINVAL;
259 	}
260 
261 	x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
262 		calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
263 		sizeof(struct ipv6_destopt_hao);
264 	WARN_ON(x->props.header_len != 24);
265 
266 	return 0;
267 }
268 
269 /*
270  * Do nothing about destroying since it has no specific operation for
271  * destination options header unlike IPsec protocols.
272  */
mip6_destopt_destroy(struct xfrm_state * x)273 static void mip6_destopt_destroy(struct xfrm_state *x)
274 {
275 }
276 
277 static const struct xfrm_type mip6_destopt_type = {
278 	.owner		= THIS_MODULE,
279 	.proto		= IPPROTO_DSTOPTS,
280 	.flags		= XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_LOCAL_COADDR,
281 	.init_state	= mip6_destopt_init_state,
282 	.destructor	= mip6_destopt_destroy,
283 	.input		= mip6_destopt_input,
284 	.output		= mip6_destopt_output,
285 	.reject		= mip6_destopt_reject,
286 };
287 
mip6_rthdr_input(struct xfrm_state * x,struct sk_buff * skb)288 static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
289 {
290 	const struct ipv6hdr *iph = ipv6_hdr(skb);
291 	struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
292 	int err = rt2->rt_hdr.nexthdr;
293 
294 	spin_lock(&x->lock);
295 	if (!ipv6_addr_equal(&iph->daddr, (struct in6_addr *)x->coaddr) &&
296 	    !ipv6_addr_any((struct in6_addr *)x->coaddr))
297 		err = -ENOENT;
298 	spin_unlock(&x->lock);
299 
300 	return err;
301 }
302 
303 /* Routing Header type 2 is inserted.
304  * IP Header's dst address is replaced with Routing Header's Home Address.
305  */
mip6_rthdr_output(struct xfrm_state * x,struct sk_buff * skb)306 static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
307 {
308 	struct ipv6hdr *iph;
309 	struct rt2_hdr *rt2;
310 	u8 nexthdr;
311 
312 	skb_push(skb, -skb_network_offset(skb));
313 	iph = ipv6_hdr(skb);
314 
315 	nexthdr = *skb_mac_header(skb);
316 	*skb_mac_header(skb) = IPPROTO_ROUTING;
317 
318 	rt2 = (struct rt2_hdr *)skb_transport_header(skb);
319 	rt2->rt_hdr.nexthdr = nexthdr;
320 	rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
321 	rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
322 	rt2->rt_hdr.segments_left = 1;
323 	memset(&rt2->reserved, 0, sizeof(rt2->reserved));
324 
325 	WARN_ON(rt2->rt_hdr.hdrlen != 2);
326 
327 	memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
328 	spin_lock_bh(&x->lock);
329 	memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
330 	spin_unlock_bh(&x->lock);
331 
332 	return 0;
333 }
334 
mip6_rthdr_init_state(struct xfrm_state * x,struct netlink_ext_ack * extack)335 static int mip6_rthdr_init_state(struct xfrm_state *x, struct netlink_ext_ack *extack)
336 {
337 	if (x->id.spi) {
338 		NL_SET_ERR_MSG(extack, "SPI must be 0");
339 		return -EINVAL;
340 	}
341 	if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
342 		NL_SET_ERR_MSG(extack, "XFRM mode must be XFRM_MODE_ROUTEOPTIMIZATION");
343 		return -EINVAL;
344 	}
345 
346 	x->props.header_len = sizeof(struct rt2_hdr);
347 
348 	return 0;
349 }
350 
351 /*
352  * Do nothing about destroying since it has no specific operation for routing
353  * header type 2 unlike IPsec protocols.
354  */
mip6_rthdr_destroy(struct xfrm_state * x)355 static void mip6_rthdr_destroy(struct xfrm_state *x)
356 {
357 }
358 
359 static const struct xfrm_type mip6_rthdr_type = {
360 	.owner		= THIS_MODULE,
361 	.proto		= IPPROTO_ROUTING,
362 	.flags		= XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_REMOTE_COADDR,
363 	.init_state	= mip6_rthdr_init_state,
364 	.destructor	= mip6_rthdr_destroy,
365 	.input		= mip6_rthdr_input,
366 	.output		= mip6_rthdr_output,
367 };
368 
mip6_init(void)369 static int __init mip6_init(void)
370 {
371 	pr_info("Mobile IPv6\n");
372 
373 	if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
374 		pr_info("%s: can't add xfrm type(destopt)\n", __func__);
375 		goto mip6_destopt_xfrm_fail;
376 	}
377 	if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
378 		pr_info("%s: can't add xfrm type(rthdr)\n", __func__);
379 		goto mip6_rthdr_xfrm_fail;
380 	}
381 	if (rawv6_mh_filter_register(mip6_mh_filter) < 0) {
382 		pr_info("%s: can't add rawv6 mh filter\n", __func__);
383 		goto mip6_rawv6_mh_fail;
384 	}
385 
386 
387 	return 0;
388 
389  mip6_rawv6_mh_fail:
390 	xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
391  mip6_rthdr_xfrm_fail:
392 	xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
393  mip6_destopt_xfrm_fail:
394 	return -EAGAIN;
395 }
396 
mip6_fini(void)397 static void __exit mip6_fini(void)
398 {
399 	if (rawv6_mh_filter_unregister(mip6_mh_filter) < 0)
400 		pr_info("%s: can't remove rawv6 mh filter\n", __func__);
401 	xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
402 	xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
403 }
404 
405 module_init(mip6_init);
406 module_exit(mip6_fini);
407 
408 MODULE_LICENSE("GPL");
409 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_DSTOPTS);
410 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ROUTING);
411