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
26static inline unsigned int calc_padlen(unsigned int len, unsigned int n)
27{
28 return (n - len + 16) & 0x7;
29}
30
31static 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
46static inline void mip6_param_prob(struct sk_buff *skb, u8 code, int pos)
47{
48 icmpv6_send(skb, ICMPV6_PARAMPROB, code, info: pos);
49}
50
51static 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
74static 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, offset: skb_transport_offset(skb),
80 len: sizeof(_hdr), buffer: &_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(type: 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, code: 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, code: 0, offsetof(struct ip6_mh, ip6mh_proto) +
100 skb_network_header_len(skb));
101 return -1;
102 }
103
104 return 0;
105}
106
107struct 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
115static struct mip6_report_rate_limiter mip6_report_rl = {
116 .lock = __SPIN_LOCK_UNLOCKED(mip6_report_rl.lock)
117};
118
119static 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(lock: &x->lock);
126 if (!ipv6_addr_equal(a1: &iph->saddr, a2: (struct in6_addr *)x->coaddr) &&
127 !ipv6_addr_any(a: (struct in6_addr *)x->coaddr))
128 err = -ENOENT;
129 spin_unlock(lock: &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 */
138static 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, len: -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(data: (char *)(dstopt + 1),
156 padlen: calc_padlen(len: sizeof(*dstopt), n: 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(lock: &x->lock);
166 memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
167 spin_unlock_bh(lock: &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
175static 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(lock: &mip6_report_rl.lock);
182 if (mip6_report_rl.stamp != stamp ||
183 mip6_report_rl.iif != iif ||
184 !ipv6_addr_equal(a1: &mip6_report_rl.src, a2: src) ||
185 !ipv6_addr_equal(a1: &mip6_report_rl.dst, a2: 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(lock: &mip6_report_rl.lock);
193 return allow;
194}
195
196static 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, offset: 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, dst: &ipv6_hdr(skb)->daddr,
222 src: hao ? &hao->addr : &ipv6_hdr(skb)->saddr,
223 iif: 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, uli: &fl6->uli);
236 if (sel.dport)
237 sel.dport_mask = htons(~0);
238 sel.sport = xfrm_flowi_sport(fl, uli: &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: &sel,
244 addr: (hao ? (xfrm_address_t *)&hao->addr : NULL));
245
246 out:
247 return err;
248}
249
250static 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(len: sizeof(struct ipv6_destopt_hdr), n: 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 */
273static void mip6_destopt_destroy(struct xfrm_state *x)
274{
275}
276
277static 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
288static 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(lock: &x->lock);
295 if (!ipv6_addr_equal(a1: &iph->daddr, a2: (struct in6_addr *)x->coaddr) &&
296 !ipv6_addr_any(a: (struct in6_addr *)x->coaddr))
297 err = -ENOENT;
298 spin_unlock(lock: &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 */
306static 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, len: -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(lock: &x->lock);
329 memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
330 spin_unlock_bh(lock: &x->lock);
331
332 return 0;
333}
334
335static 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 */
355static void mip6_rthdr_destroy(struct xfrm_state *x)
356{
357}
358
359static 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
369static int __init mip6_init(void)
370{
371 pr_info("Mobile IPv6\n");
372
373 if (xfrm_register_type(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(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(filter: 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(type: &mip6_rthdr_type, AF_INET6);
391 mip6_rthdr_xfrm_fail:
392 xfrm_unregister_type(type: &mip6_destopt_type, AF_INET6);
393 mip6_destopt_xfrm_fail:
394 return -EAGAIN;
395}
396
397static void __exit mip6_fini(void)
398{
399 if (rawv6_mh_filter_unregister(filter: mip6_mh_filter) < 0)
400 pr_info("%s: can't remove rawv6 mh filter\n", __func__);
401 xfrm_unregister_type(type: &mip6_rthdr_type, AF_INET6);
402 xfrm_unregister_type(type: &mip6_destopt_type, AF_INET6);
403}
404
405module_init(mip6_init);
406module_exit(mip6_fini);
407
408MODULE_LICENSE("GPL");
409MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_DSTOPTS);
410MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ROUTING);
411

source code of linux/net/ipv6/mip6.c