net/ipv6/exthdrs.c

   1 /*
   2  *      Extension Header handling for IPv6
   3  *      Linux INET6 implementation
   4  *
   5  *      Authors:
   6  *      Pedro Roque             <roque@di.fc.ul.pt>
   7  *      Andi Kleen              <ak@muc.de>
   8  *      Alexey Kuznetsov        <kuznet@ms2.inr.ac.ru>
   9  *
  10  *      This program is free software; you can redistribute it and/or
  11  *      modify it under the terms of the GNU General Public License
  12  *      as published by the Free Software Foundation; either version
  13  *      2 of the License, or (at your option) any later version.
  14  */
  15
  16 /* Changes:
  17  *      yoshfuji                : ensure not to overrun while parsing
  18  *                                tlv options.
  19  *      Mitsuru KANDA @USAGI and: Remove ipv6_parse_exthdrs().
  20  *      YOSHIFUJI Hideaki @USAGI  Register inbound extension header
  21  *                                handlers as inet6_protocol{}.
  22  */
  23
  24 #include <linux/errno.h>
  25 #include <linux/types.h>
  26 #include <linux/socket.h>
  27 #include <linux/sockios.h>
  28 #include <linux/net.h>
  29 #include <linux/netdevice.h>
  30 #include <linux/in6.h>
  31 #include <linux/icmpv6.h>
  32
  33 #include <net/dst.h>
  34 #include <net/sock.h>
  35 #include <net/snmp.h>
  36
  37 #include <net/ipv6.h>
  38 #include <net/protocol.h>
  39 #include <net/transp_v6.h>
  40 #include <net/rawv6.h>
  41 #include <net/ndisc.h>
  42 #include <net/ip6_route.h>
  43 #include <net/addrconf.h>
  44 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
  45 #include <net/xfrm.h>
  46 #endif
  47
  48 #include <asm/uaccess.h>
  49
  50 int ipv6_find_tlv(struct sk_buff *skb, int offset, int type)
  51 {
  52         const unsigned char *nh = skb_network_header(skb);
  53         int packet_len = skb->tail - skb->network_header;
  54         struct ipv6_opt_hdr *hdr;
  55         int len;
  56
  57         if (offset + 2 > packet_len)
  58                 goto bad;
  59         hdr = (struct ipv6_opt_hdr *)(nh + offset);
  60         len = ((hdr->hdrlen + 1) << 3);
  61
  62         if (offset + len > packet_len)
  63                 goto bad;
  64
  65         offset += 2;
  66         len -= 2;
  67
  68         while (len > 0) {
  69                 int opttype = nh[offset];
  70                 int optlen;
  71
  72                 if (opttype == type)
  73                         return offset;
  74
  75                 switch (opttype) {
  76                 case IPV6_TLV_PAD0:
  77                         optlen = 1;
  78                         break;
  79                 default:
  80                         optlen = nh[offset + 1] + 2;
  81                         if (optlen > len)
  82                                 goto bad;
  83                         break;
  84                 }
  85                 offset += optlen;
  86                 len -= optlen;
  87         }
  88         /* not_found */
  89  bad:
  90         return -1;
  91 }
  92 EXPORT_SYMBOL_GPL(ipv6_find_tlv);
  93
  94 /*
  95  *      Parsing tlv encoded headers.
  96  *
  97  *      Parsing function "func" returns 1, if parsing succeed
  98  *      and 0, if it failed.
  99  *      It MUST NOT touch skb->h.
 100  */
 101
 102 struct tlvtype_proc {
 103         int     type;
 104         int     (*func)(struct sk_buff *skb, int offset);
 105 };
 106
 107 /*********************
 108   Generic functions
 109  *********************/
 110
 111 /* An unknown option is detected, decide what to do */
 112
 113 static int ip6_tlvopt_unknown(struct sk_buff *skb, int optoff)
 114 {
 115         switch ((skb_network_header(skb)[optoff] & 0xC0) >> 6) {
 116         case 0: /* ignore */
 117                 return 1;
 118
 119         case 1: /* drop packet */
 120                 break;
 121
 122         case 3: /* Send ICMP if not a multicast address and drop packet */
 123                 /* Actually, it is redundant check. icmp_send
 124                    will recheck in any case.
 125                  */
 126                 if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr))
 127                         break;
 128         case 2: /* send ICMP PARM PROB regardless and drop packet */
 129                 icmpv6_param_prob(skb, ICMPV6_UNK_OPTION, optoff);
 130                 return 0;
 131         }
 132
 133         kfree_skb(skb);
 134         return 0;
 135 }
 136
 137 /* Parse tlv encoded option header (hop-by-hop or destination) */
 138
 139 static int ip6_parse_tlv(struct tlvtype_proc *procs, struct sk_buff *skb)
 140 {
 141         struct tlvtype_proc *curr;
 142         const unsigned char *nh = skb_network_header(skb);
 143         int off = skb_network_header_len(skb);
 144         int len = (skb_transport_header(skb)[1] + 1) << 3;
 145
 146         if (skb_transport_offset(skb) + len > skb_headlen(skb))
 147                 goto bad;
 148
 149         off += 2;
 150         len -= 2;
 151
 152         while (len > 0) {
 153                 int optlen = nh[off + 1] + 2;
 154
 155                 switch (nh[off]) {
 156                 case IPV6_TLV_PAD0:
 157                         optlen = 1;
 158                         break;
 159
 160                 case IPV6_TLV_PADN:
 161                         break;
 162
 163                 default: /* Other TLV code so scan list */
 164                         if (optlen > len)
 165                                 goto bad;
 166                         for (curr=procs; curr->type >= 0; curr++) {
 167                                 if (curr->type == nh[off]) {
 168                                         /* type specific length/alignment
 169                                            checks will be performed in the
 170                                            func(). */
 171                                         if (curr->func(skb, off) == 0)
 172                                                 return 0;
 173                                         break;
 174                                 }
 175                         }
 176                         if (curr->type < 0) {
 177                                 if (ip6_tlvopt_unknown(skb, off) == 0)
 178                                         return 0;
 179                         }
 180                         break;
 181                 }
 182                 off += optlen;
 183                 len -= optlen;
 184         }
 185         if (len == 0)
 186                 return 1;
 187 bad:
 188         kfree_skb(skb);
 189         return 0;
 190 }
 191
 192 /*****************************
 193   Destination options header.
 194  *****************************/
 195
 196 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 197 static int ipv6_dest_hao(struct sk_buff *skb, int optoff)
 198 {
 199         struct ipv6_destopt_hao *hao;
 200         struct inet6_skb_parm *opt = IP6CB(skb);
 201         struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 202         struct in6_addr tmp_addr;
 203         int ret;
 204
 205         if (opt->dsthao) {
 206                 LIMIT_NETDEBUG(KERN_DEBUG "hao duplicated\n");
 207                 goto discard;
 208         }
 209         opt->dsthao = opt->dst1;
 210         opt->dst1 = 0;
 211
 212         hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) + optoff);
 213
 214         if (hao->length != 16) {
 215                 LIMIT_NETDEBUG(
 216                         KERN_DEBUG "hao invalid option length = %d\n", hao->length);
 217                 goto discard;
 218         }
 219
 220         if (!(ipv6_addr_type(&hao->addr) & IPV6_ADDR_UNICAST)) {
 221                 LIMIT_NETDEBUG(
 222                         KERN_DEBUG "hao is not an unicast addr: " NIP6_FMT "\n", NIP6(hao->addr));
 223                 goto discard;
 224         }
 225
 226         ret = xfrm6_input_addr(skb, (xfrm_address_t *)&ipv6h->daddr,
 227                                (xfrm_address_t *)&hao->addr, IPPROTO_DSTOPTS);
 228         if (unlikely(ret < 0))
 229                 goto discard;
 230
 231         if (skb_cloned(skb)) {
 232                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 233                         goto discard;
 234
 235                 /* update all variable using below by copied skbuff */
 236                 hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) +
 237                                                   optoff);
 238                 ipv6h = ipv6_hdr(skb);
 239         }
 240
 241         if (skb->ip_summed == CHECKSUM_COMPLETE)
 242                 skb->ip_summed = CHECKSUM_NONE;
 243
 244         ipv6_addr_copy(&tmp_addr, &ipv6h->saddr);
 245         ipv6_addr_copy(&ipv6h->saddr, &hao->addr);
 246         ipv6_addr_copy(&hao->addr, &tmp_addr);
 247
 248         if (skb->tstamp.tv64 == 0)
 249                 __net_timestamp(skb);
 250
 251         return 1;
 252
 253  discard:
 254         kfree_skb(skb);
 255         return 0;
 256 }
 257 #endif
 258
 259 static struct tlvtype_proc tlvprocdestopt_lst[] = {
 260 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 261         {
 262                 .type   = IPV6_TLV_HAO,
 263                 .func   = ipv6_dest_hao,
 264         },
 265 #endif
 266         {-1,                    NULL}
 267 };
 268
 269 static int ipv6_destopt_rcv(struct sk_buff *skb)
 270 {
 271         struct inet6_skb_parm *opt = IP6CB(skb);
 272 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 273         __u16 dstbuf;
 274 #endif
 275         struct dst_entry *dst;
 276
 277         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 278             !pskb_may_pull(skb, (skb_transport_offset(skb) +
 279                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 280                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 281                                  IPSTATS_MIB_INHDRERRORS);
 282                 kfree_skb(skb);
 283                 return -1;
 284         }
 285
 286         opt->lastopt = opt->dst1 = skb_network_header_len(skb);
 287 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 288         dstbuf = opt->dst1;
 289 #endif
 290
 291         dst = dst_clone(skb->dst);
 292         if (ip6_parse_tlv(tlvprocdestopt_lst, skb)) {
 293                 dst_release(dst);
 294                 skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
 295                 opt = IP6CB(skb);
 296 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 297                 opt->nhoff = dstbuf;
 298 #else
 299                 opt->nhoff = opt->dst1;
 300 #endif
 301                 return 1;
 302         }
 303
 304         IP6_INC_STATS_BH(ip6_dst_idev(dst), IPSTATS_MIB_INHDRERRORS);
 305         dst_release(dst);
 306         return -1;
 307 }
 308
 309 /********************************
 310   Routing header.
 311  ********************************/
 312
 313 static int ipv6_rthdr_rcv(struct sk_buff *skb)
 314 {
 315         struct inet6_skb_parm *opt = IP6CB(skb);
 316         struct in6_addr *addr = NULL;
 317         struct in6_addr daddr;
 318         struct inet6_dev *idev;
 319         int n, i;
 320         struct ipv6_rt_hdr *hdr;
 321         struct rt0_hdr *rthdr;
 322         int accept_source_route = ipv6_devconf.accept_source_route;
 323
 324         idev = in6_dev_get(skb->dev);
 325         if (idev) {
 326                 if (accept_source_route > idev->cnf.accept_source_route)
 327                         accept_source_route = idev->cnf.accept_source_route;
 328                 in6_dev_put(idev);
 329         }
 330
 331         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 332             !pskb_may_pull(skb, (skb_transport_offset(skb) +
 333                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 334                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 335                                  IPSTATS_MIB_INHDRERRORS);
 336                 kfree_skb(skb);
 337                 return -1;
 338         }
 339
 340         hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 341
 342         if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ||
 343             skb->pkt_type != PACKET_HOST) {
 344                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 345                                  IPSTATS_MIB_INADDRERRORS);
 346                 kfree_skb(skb);
 347                 return -1;
 348         }
 349
 350 looped_back:
 351         if (hdr->segments_left == 0) {
 352                 switch (hdr->type) {
 353 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 354                 case IPV6_SRCRT_TYPE_2:
 355                         /* Silently discard type 2 header unless it was
 356                          * processed by own
 357                          */
 358                         if (!addr) {
 359                                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 360                                                  IPSTATS_MIB_INADDRERRORS);
 361                                 kfree_skb(skb);
 362                                 return -1;
 363                         }
 364                         break;
 365 #endif
 366                 default:
 367                         break;
 368                 }
 369
 370                 opt->lastopt = opt->srcrt = skb_network_header_len(skb);
 371                 skb->transport_header += (hdr->hdrlen + 1) << 3;
 372                 opt->dst0 = opt->dst1;
 373                 opt->dst1 = 0;
 374                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
 375                 return 1;
 376         }
 377
 378         switch (hdr->type) {
 379 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 380         case IPV6_SRCRT_TYPE_2:
 381                 if (accept_source_route < 0)
 382                         goto unknown_rh;
 383                 /* Silently discard invalid RTH type 2 */
 384                 if (hdr->hdrlen != 2 || hdr->segments_left != 1) {
 385                         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 386                                          IPSTATS_MIB_INHDRERRORS);
 387                         kfree_skb(skb);
 388                         return -1;
 389                 }
 390                 break;
 391 #endif
 392         default:
 393                 goto unknown_rh;
 394         }
 395
 396         /*
 397          *      This is the routing header forwarding algorithm from
 398          *      RFC 2460, page 16.
 399          */
 400
 401         n = hdr->hdrlen >> 1;
 402
 403         if (hdr->segments_left > n) {
 404                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 405                                  IPSTATS_MIB_INHDRERRORS);
 406                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 407                                   ((&hdr->segments_left) -
 408                                    skb_network_header(skb)));
 409                 return -1;
 410         }
 411
 412         /* We are about to mangle packet header. Be careful!
 413            Do not damage packets queued somewhere.
 414          */
 415         if (skb_cloned(skb)) {
 416                 /* the copy is a forwarded packet */
 417                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
 418                         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 419                                          IPSTATS_MIB_OUTDISCARDS);
 420                         kfree_skb(skb);
 421                         return -1;
 422                 }
 423                 hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 424         }
 425
 426         if (skb->ip_summed == CHECKSUM_COMPLETE)
 427                 skb->ip_summed = CHECKSUM_NONE;
 428
 429         i = n - --hdr->segments_left;
 430
 431         rthdr = (struct rt0_hdr *) hdr;
 432         addr = rthdr->addr;
 433         addr += i - 1;
 434
 435         switch (hdr->type) {
 436 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 437         case IPV6_SRCRT_TYPE_2:
 438                 if (xfrm6_input_addr(skb, (xfrm_address_t *)addr,
 439                                      (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 440                                      IPPROTO_ROUTING) < 0) {
 441                         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 442                                          IPSTATS_MIB_INADDRERRORS);
 443                         kfree_skb(skb);
 444                         return -1;
 445                 }
 446                 if (!ipv6_chk_home_addr(dev_net(skb->dst->dev), addr)) {
 447                         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 448                                          IPSTATS_MIB_INADDRERRORS);
 449                         kfree_skb(skb);
 450                         return -1;
 451                 }
 452                 break;
 453 #endif
 454         default:
 455                 break;
 456         }
 457
 458         if (ipv6_addr_is_multicast(addr)) {
 459                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 460                                  IPSTATS_MIB_INADDRERRORS);
 461                 kfree_skb(skb);
 462                 return -1;
 463         }
 464
 465         ipv6_addr_copy(&daddr, addr);
 466         ipv6_addr_copy(addr, &ipv6_hdr(skb)->daddr);
 467         ipv6_addr_copy(&ipv6_hdr(skb)->daddr, &daddr);
 468
 469         dst_release(xchg(&skb->dst, NULL));
 470         ip6_route_input(skb);
 471         if (skb->dst->error) {
 472                 skb_push(skb, skb->data - skb_network_header(skb));
 473                 dst_input(skb);
 474                 return -1;
 475         }
 476
 477         if (skb->dst->dev->flags&IFF_LOOPBACK) {
 478                 if (ipv6_hdr(skb)->hop_limit <= 1) {
 479                         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 480                                          IPSTATS_MIB_INHDRERRORS);
 481                         icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
 482                                     0, skb->dev);
 483                         kfree_skb(skb);
 484                         return -1;
 485                 }
 486                 ipv6_hdr(skb)->hop_limit--;
 487                 goto looped_back;
 488         }
 489
 490         skb_push(skb, skb->data - skb_network_header(skb));
 491         dst_input(skb);
 492         return -1;
 493
 494 unknown_rh:
 495         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_INHDRERRORS);
 496         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 497                           (&hdr->type) - skb_network_header(skb));
 498         return -1;
 499 }
 500
 501 static struct inet6_protocol rthdr_protocol = {
 502         .handler        =       ipv6_rthdr_rcv,
 503         .flags          =       INET6_PROTO_NOPOLICY | INET6_PROTO_GSO_EXTHDR,
 504 };
 505
 506 static struct inet6_protocol destopt_protocol = {
 507         .handler        =       ipv6_destopt_rcv,
 508         .flags          =       INET6_PROTO_NOPOLICY | INET6_PROTO_GSO_EXTHDR,
 509 };
 510
 511 static struct inet6_protocol nodata_protocol = {
 512         .handler        =       dst_discard,
 513         .flags          =       INET6_PROTO_NOPOLICY,
 514 };
 515
 516 int __init ipv6_exthdrs_init(void)
 517 {
 518         int ret;
 519
 520         ret = inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 521         if (ret)
 522                 goto out;
 523
 524         ret = inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 525         if (ret)
 526                 goto out_rthdr;
 527
 528         ret = inet6_add_protocol(&nodata_protocol, IPPROTO_NONE);
 529         if (ret)
 530                 goto out_destopt;
 531
 532 out:
 533         return ret;
 534 out_rthdr:
 535         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 536 out_destopt:
 537         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 538         goto out;
 539 };
 540
 541 void ipv6_exthdrs_exit(void)
 542 {
 543         inet6_del_protocol(&nodata_protocol, IPPROTO_NONE);
 544         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 545         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 546 }
 547
 548 /**********************************
 549   Hop-by-hop options.
 550  **********************************/
 551
 552 /*
 553  * Note: we cannot rely on skb->dst before we assign it in ip6_route_input().
 554  */
 555 static inline struct inet6_dev *ipv6_skb_idev(struct sk_buff *skb)
 556 {
 557         return skb->dst ? ip6_dst_idev(skb->dst) : __in6_dev_get(skb->dev);
 558 }
 559
 560 /* Router Alert as of RFC 2711 */
 561
 562 static int ipv6_hop_ra(struct sk_buff *skb, int optoff)
 563 {
 564         const unsigned char *nh = skb_network_header(skb);
 565
 566         if (nh[optoff + 1] == 2) {
 567                 IP6CB(skb)->ra = optoff;
 568                 return 1;
 569         }
 570         LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_ra: wrong RA length %d\n",
 571                        nh[optoff + 1]);
 572         kfree_skb(skb);
 573         return 0;
 574 }
 575
 576 /* Jumbo payload */
 577
 578 static int ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
 579 {
 580         const unsigned char *nh = skb_network_header(skb);
 581         u32 pkt_len;
 582
 583         if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
 584                 LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
 585                                nh[optoff+1]);
 586                 IP6_INC_STATS_BH(ipv6_skb_idev(skb),
 587                                  IPSTATS_MIB_INHDRERRORS);
 588                 goto drop;
 589         }
 590
 591         pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
 592         if (pkt_len <= IPV6_MAXPLEN) {
 593                 IP6_INC_STATS_BH(ipv6_skb_idev(skb), IPSTATS_MIB_INHDRERRORS);
 594                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2);
 595                 return 0;
 596         }
 597         if (ipv6_hdr(skb)->payload_len) {
 598                 IP6_INC_STATS_BH(ipv6_skb_idev(skb), IPSTATS_MIB_INHDRERRORS);
 599                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff);
 600                 return 0;
 601         }
 602
 603         if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
 604                 IP6_INC_STATS_BH(ipv6_skb_idev(skb), IPSTATS_MIB_INTRUNCATEDPKTS);
 605                 goto drop;
 606         }
 607
 608         if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 609                 goto drop;
 610
 611         return 1;
 612
 613 drop:
 614         kfree_skb(skb);
 615         return 0;
 616 }
 617
 618 static struct tlvtype_proc tlvprochopopt_lst[] = {
 619         {
 620                 .type   = IPV6_TLV_ROUTERALERT,
 621                 .func   = ipv6_hop_ra,
 622         },
 623         {
 624                 .type   = IPV6_TLV_JUMBO,
 625                 .func   = ipv6_hop_jumbo,
 626         },
 627         { -1, }
 628 };
 629
 630 int ipv6_parse_hopopts(struct sk_buff *skb)
 631 {
 632         struct inet6_skb_parm *opt = IP6CB(skb);
 633
 634         /*
 635          * skb_network_header(skb) is equal to skb->data, and
 636          * skb_network_header_len(skb) is always equal to
 637          * sizeof(struct ipv6hdr) by definition of
 638          * hop-by-hop options.
 639          */
 640         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
 641             !pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
 642                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 643                 kfree_skb(skb);
 644                 return -1;
 645         }
 646
 647         opt->hop = sizeof(struct ipv6hdr);
 648         if (ip6_parse_tlv(tlvprochopopt_lst, skb)) {
 649                 skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
 650                 opt = IP6CB(skb);
 651                 opt->nhoff = sizeof(struct ipv6hdr);
 652                 return 1;
 653         }
 654         return -1;
 655 }
 656
 657 /*
 658  *      Creating outbound headers.
 659  *
 660  *      "build" functions work when skb is filled from head to tail (datagram)
 661  *      "push"  functions work when headers are added from tail to head (tcp)
 662  *
 663  *      In both cases we assume, that caller reserved enough room
 664  *      for headers.
 665  */
 666
 667 static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
 668                             struct ipv6_rt_hdr *opt,
 669                             struct in6_addr **addr_p)
 670 {
 671         struct rt0_hdr *phdr, *ihdr;
 672         int hops;
 673
 674         ihdr = (struct rt0_hdr *) opt;
 675
 676         phdr = (struct rt0_hdr *) skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
 677         memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
 678
 679         hops = ihdr->rt_hdr.hdrlen >> 1;
 680
 681         if (hops > 1)
 682                 memcpy(phdr->addr, ihdr->addr + 1,
 683                        (hops - 1) * sizeof(struct in6_addr));
 684
 685         ipv6_addr_copy(phdr->addr + (hops - 1), *addr_p);
 686         *addr_p = ihdr->addr;
 687
 688         phdr->rt_hdr.nexthdr = *proto;
 689         *proto = NEXTHDR_ROUTING;
 690 }
 691
 692 static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
 693 {
 694         struct ipv6_opt_hdr *h = (struct ipv6_opt_hdr *)skb_push(skb, ipv6_optlen(opt));
 695
 696         memcpy(h, opt, ipv6_optlen(opt));
 697         h->nexthdr = *proto;
 698         *proto = type;
 699 }
 700
 701 void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
 702                           u8 *proto,
 703                           struct in6_addr **daddr)
 704 {
 705         if (opt->srcrt) {
 706                 ipv6_push_rthdr(skb, proto, opt->srcrt, daddr);
 707                 /*
 708                  * IPV6_RTHDRDSTOPTS is ignored
 709                  * unless IPV6_RTHDR is set (RFC3542).
 710                  */
 711                 if (opt->dst0opt)
 712                         ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
 713         }
 714         if (opt->hopopt)
 715                 ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
 716 }
 717
 718 EXPORT_SYMBOL(ipv6_push_nfrag_opts);
 719
 720 void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
 721 {
 722         if (opt->dst1opt)
 723                 ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
 724 }
 725
 726 struct ipv6_txoptions *
 727 ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
 728 {
 729         struct ipv6_txoptions *opt2;
 730
 731         opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
 732         if (opt2) {
 733                 long dif = (char*)opt2 - (char*)opt;
 734                 memcpy(opt2, opt, opt->tot_len);
 735                 if (opt2->hopopt)
 736                         *((char**)&opt2->hopopt) += dif;
 737                 if (opt2->dst0opt)
 738                         *((char**)&opt2->dst0opt) += dif;
 739                 if (opt2->dst1opt)
 740                         *((char**)&opt2->dst1opt) += dif;
 741                 if (opt2->srcrt)
 742                         *((char**)&opt2->srcrt) += dif;
 743         }
 744         return opt2;
 745 }
 746
 747 EXPORT_SYMBOL_GPL(ipv6_dup_options);
 748
 749 static int ipv6_renew_option(void *ohdr,
 750                              struct ipv6_opt_hdr __user *newopt, int newoptlen,
 751                              int inherit,
 752                              struct ipv6_opt_hdr **hdr,
 753                              char **p)
 754 {
 755         if (inherit) {
 756                 if (ohdr) {
 757                         memcpy(*p, ohdr, ipv6_optlen((struct ipv6_opt_hdr *)ohdr));
 758                         *hdr = (struct ipv6_opt_hdr *)*p;
 759                         *p += CMSG_ALIGN(ipv6_optlen(*(struct ipv6_opt_hdr **)hdr));
 760                 }
 761         } else {
 762                 if (newopt) {
 763                         if (copy_from_user(*p, newopt, newoptlen))
 764                                 return -EFAULT;
 765                         *hdr = (struct ipv6_opt_hdr *)*p;
 766                         if (ipv6_optlen(*(struct ipv6_opt_hdr **)hdr) > newoptlen)
 767                                 return -EINVAL;
 768                         *p += CMSG_ALIGN(newoptlen);
 769                 }
 770         }
 771         return 0;
 772 }
 773
 774 struct ipv6_txoptions *
 775 ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
 776                    int newtype,
 777                    struct ipv6_opt_hdr __user *newopt, int newoptlen)
 778 {
 779         int tot_len = 0;
 780         char *p;
 781         struct ipv6_txoptions *opt2;
 782         int err;
 783
 784         if (opt) {
 785                 if (newtype != IPV6_HOPOPTS && opt->hopopt)
 786                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
 787                 if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
 788                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
 789                 if (newtype != IPV6_RTHDR && opt->srcrt)
 790                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
 791                 if (newtype != IPV6_DSTOPTS && opt->dst1opt)
 792                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
 793         }
 794
 795         if (newopt && newoptlen)
 796                 tot_len += CMSG_ALIGN(newoptlen);
 797
 798         if (!tot_len)
 799                 return NULL;
 800
 801         tot_len += sizeof(*opt2);
 802         opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
 803         if (!opt2)
 804                 return ERR_PTR(-ENOBUFS);
 805
 806         memset(opt2, 0, tot_len);
 807
 808         opt2->tot_len = tot_len;
 809         p = (char *)(opt2 + 1);
 810
 811         err = ipv6_renew_option(opt ? opt->hopopt : NULL, newopt, newoptlen,
 812                                 newtype != IPV6_HOPOPTS,
 813                                 &opt2->hopopt, &p);
 814         if (err)
 815                 goto out;
 816
 817         err = ipv6_renew_option(opt ? opt->dst0opt : NULL, newopt, newoptlen,
 818                                 newtype != IPV6_RTHDRDSTOPTS,
 819                                 &opt2->dst0opt, &p);
 820         if (err)
 821                 goto out;
 822
 823         err = ipv6_renew_option(opt ? opt->srcrt : NULL, newopt, newoptlen,
 824                                 newtype != IPV6_RTHDR,
 825                                 (struct ipv6_opt_hdr **)&opt2->srcrt, &p);
 826         if (err)
 827                 goto out;
 828
 829         err = ipv6_renew_option(opt ? opt->dst1opt : NULL, newopt, newoptlen,
 830                                 newtype != IPV6_DSTOPTS,
 831                                 &opt2->dst1opt, &p);
 832         if (err)
 833                 goto out;
 834
 835         opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
 836                           (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
 837                           (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
 838         opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
 839
 840         return opt2;
 841 out:
 842         sock_kfree_s(sk, opt2, opt2->tot_len);
 843         return ERR_PTR(err);
 844 }
 845
 846 struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space,
 847                                           struct ipv6_txoptions *opt)
 848 {
 849         /*
 850          * ignore the dest before srcrt unless srcrt is being included.
 851          * --yoshfuji
 852          */
 853         if (opt && opt->dst0opt && !opt->srcrt) {
 854                 if (opt_space != opt) {
 855                         memcpy(opt_space, opt, sizeof(*opt_space));
 856                         opt = opt_space;
 857                 }
 858                 opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
 859                 opt->dst0opt = NULL;
 860         }
 861
 862         return opt;
 863 }
 864