net/ipv6/mip6.c

   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
  26 static inline unsigned int calc_padlen(unsigned int len, unsigned int n)
  27 {
  28         return (n - len + 16) & 0x7;
  29 }
  30
  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
  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
  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
  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
 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  */
 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
 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
 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
 250 static int mip6_destopt_init_state(struct xfrm_state *x)
 251 {
 252         if (x->id.spi) {
 253                 pr_info("%s: spi is not 0: %u\n", __func__, x->id.spi);
 254                 return -EINVAL;
 255         }
 256         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 257                 pr_info("%s: state's mode is not %u: %u\n",
 258                         __func__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 259                 return -EINVAL;
 260         }
 261
 262         x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
 263                 calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
 264                 sizeof(struct ipv6_destopt_hao);
 265         WARN_ON(x->props.header_len != 24);
 266
 267         return 0;
 268 }
 269
 270 /*
 271  * Do nothing about destroying since it has no specific operation for
 272  * destination options header unlike IPsec protocols.
 273  */
 274 static void mip6_destopt_destroy(struct xfrm_state *x)
 275 {
 276 }
 277
 278 static const struct xfrm_type mip6_destopt_type = {
 279         .owner          = THIS_MODULE,
 280         .proto          = IPPROTO_DSTOPTS,
 281         .flags          = XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_LOCAL_COADDR,
 282         .init_state     = mip6_destopt_init_state,
 283         .destructor     = mip6_destopt_destroy,
 284         .input          = mip6_destopt_input,
 285         .output         = mip6_destopt_output,
 286         .reject         = mip6_destopt_reject,
 287 };
 288
 289 static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
 290 {
 291         const struct ipv6hdr *iph = ipv6_hdr(skb);
 292         struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
 293         int err = rt2->rt_hdr.nexthdr;
 294
 295         spin_lock(&x->lock);
 296         if (!ipv6_addr_equal(&iph->daddr, (struct in6_addr *)x->coaddr) &&
 297             !ipv6_addr_any((struct in6_addr *)x->coaddr))
 298                 err = -ENOENT;
 299         spin_unlock(&x->lock);
 300
 301         return err;
 302 }
 303
 304 /* Routing Header type 2 is inserted.
 305  * IP Header's dst address is replaced with Routing Header's Home Address.
 306  */
 307 static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
 308 {
 309         struct ipv6hdr *iph;
 310         struct rt2_hdr *rt2;
 311         u8 nexthdr;
 312
 313         skb_push(skb, -skb_network_offset(skb));
 314         iph = ipv6_hdr(skb);
 315
 316         nexthdr = *skb_mac_header(skb);
 317         *skb_mac_header(skb) = IPPROTO_ROUTING;
 318
 319         rt2 = (struct rt2_hdr *)skb_transport_header(skb);
 320         rt2->rt_hdr.nexthdr = nexthdr;
 321         rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
 322         rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
 323         rt2->rt_hdr.segments_left = 1;
 324         memset(&rt2->reserved, 0, sizeof(rt2->reserved));
 325
 326         WARN_ON(rt2->rt_hdr.hdrlen != 2);
 327
 328         memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
 329         spin_lock_bh(&x->lock);
 330         memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
 331         spin_unlock_bh(&x->lock);
 332
 333         return 0;
 334 }
 335
 336 static int mip6_rthdr_init_state(struct xfrm_state *x)
 337 {
 338         if (x->id.spi) {
 339                 pr_info("%s: spi is not 0: %u\n", __func__, x->id.spi);
 340                 return -EINVAL;
 341         }
 342         if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 343                 pr_info("%s: state's mode is not %u: %u\n",
 344                         __func__, XFRM_MODE_ROUTEOPTIMIZATION, x->props.mode);
 345                 return -EINVAL;
 346         }
 347
 348         x->props.header_len = sizeof(struct rt2_hdr);
 349
 350         return 0;
 351 }
 352
 353 /*
 354  * Do nothing about destroying since it has no specific operation for routing
 355  * header type 2 unlike IPsec protocols.
 356  */
 357 static void mip6_rthdr_destroy(struct xfrm_state *x)
 358 {
 359 }
 360
 361 static const struct xfrm_type mip6_rthdr_type = {
 362         .owner          = THIS_MODULE,
 363         .proto          = IPPROTO_ROUTING,
 364         .flags          = XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_REMOTE_COADDR,
 365         .init_state     = mip6_rthdr_init_state,
 366         .destructor     = mip6_rthdr_destroy,
 367         .input          = mip6_rthdr_input,
 368         .output         = mip6_rthdr_output,
 369 };
 370
 371 static int __init mip6_init(void)
 372 {
 373         pr_info("Mobile IPv6\n");
 374
 375         if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
 376                 pr_info("%s: can't add xfrm type(destopt)\n", __func__);
 377                 goto mip6_destopt_xfrm_fail;
 378         }
 379         if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
 380                 pr_info("%s: can't add xfrm type(rthdr)\n", __func__);
 381                 goto mip6_rthdr_xfrm_fail;
 382         }
 383         if (rawv6_mh_filter_register(mip6_mh_filter) < 0) {
 384                 pr_info("%s: can't add rawv6 mh filter\n", __func__);
 385                 goto mip6_rawv6_mh_fail;
 386         }
 387
 388
 389         return 0;
 390
 391  mip6_rawv6_mh_fail:
 392         xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
 393  mip6_rthdr_xfrm_fail:
 394         xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
 395  mip6_destopt_xfrm_fail:
 396         return -EAGAIN;
 397 }
 398
 399 static void __exit mip6_fini(void)
 400 {
 401         if (rawv6_mh_filter_unregister(mip6_mh_filter) < 0)
 402                 pr_info("%s: can't remove rawv6 mh filter\n", __func__);
 403         xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
 404         xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
 405 }
 406
 407 module_init(mip6_init);
 408 module_exit(mip6_fini);
 409
 410 MODULE_LICENSE("GPL");
 411 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_DSTOPTS);
 412 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ROUTING);