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 #include <linux/slab.h>
  33 #include <linux/export.h>
  34
  35 #include <net/dst.h>
  36 #include <net/sock.h>
  37 #include <net/snmp.h>
  38
  39 #include <net/ipv6.h>
  40 #include <net/protocol.h>
  41 #include <net/transp_v6.h>
  42 #include <net/rawv6.h>
  43 #include <net/ndisc.h>
  44 #include <net/ip6_route.h>
  45 #include <net/addrconf.h>
  46 #if IS_ENABLED(CONFIG_IPV6_MIP6)
  47 #include <net/xfrm.h>
  48 #endif
  49
  50 #include <linux/uaccess.h>
  51
  52 /*
  53  *      Parsing tlv encoded headers.
  54  *
  55  *      Parsing function "func" returns true, if parsing succeed
  56  *      and false, if it failed.
  57  *      It MUST NOT touch skb->h.
  58  */
  59
  60 struct tlvtype_proc {
  61         int     type;
  62         bool    (*func)(struct sk_buff *skb, int offset);
  63 };
  64
  65 /*********************
  66   Generic functions
  67  *********************/
  68
  69 /* An unknown option is detected, decide what to do */
  70
  71 static bool ip6_tlvopt_unknown(struct sk_buff *skb, int optoff)
  72 {
  73         switch ((skb_network_header(skb)[optoff] & 0xC0) >> 6) {
  74         case 0: /* ignore */
  75                 return true;
  76
  77         case 1: /* drop packet */
  78                 break;
  79
  80         case 3: /* Send ICMP if not a multicast address and drop packet */
  81                 /* Actually, it is redundant check. icmp_send
  82                    will recheck in any case.
  83                  */
  84                 if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr))
  85                         break;
  86         case 2: /* send ICMP PARM PROB regardless and drop packet */
  87                 icmpv6_param_prob(skb, ICMPV6_UNK_OPTION, optoff);
  88                 return false;
  89         }
  90
  91         kfree_skb(skb);
  92         return false;
  93 }
  94
  95 /* Parse tlv encoded option header (hop-by-hop or destination) */
  96
  97 static bool ip6_parse_tlv(const struct tlvtype_proc *procs, struct sk_buff *skb)
  98 {
  99         const struct tlvtype_proc *curr;
 100         const unsigned char *nh = skb_network_header(skb);
 101         int off = skb_network_header_len(skb);
 102         int len = (skb_transport_header(skb)[1] + 1) << 3;
 103         int padlen = 0;
 104
 105         if (skb_transport_offset(skb) + len > skb_headlen(skb))
 106                 goto bad;
 107
 108         off += 2;
 109         len -= 2;
 110
 111         while (len > 0) {
 112                 int optlen = nh[off + 1] + 2;
 113                 int i;
 114
 115                 switch (nh[off]) {
 116                 case IPV6_TLV_PAD1:
 117                         optlen = 1;
 118                         padlen++;
 119                         if (padlen > 7)
 120                                 goto bad;
 121                         break;
 122
 123                 case IPV6_TLV_PADN:
 124                         /* RFC 2460 states that the purpose of PadN is
 125                          * to align the containing header to multiples
 126                          * of 8. 7 is therefore the highest valid value.
 127                          * See also RFC 4942, Section 2.1.9.5.
 128                          */
 129                         padlen += optlen;
 130                         if (padlen > 7)
 131                                 goto bad;
 132                         /* RFC 4942 recommends receiving hosts to
 133                          * actively check PadN payload to contain
 134                          * only zeroes.
 135                          */
 136                         for (i = 2; i < optlen; i++) {
 137                                 if (nh[off + i] != 0)
 138                                         goto bad;
 139                         }
 140                         break;
 141
 142                 default: /* Other TLV code so scan list */
 143                         if (optlen > len)
 144                                 goto bad;
 145                         for (curr = procs; curr->type >= 0; curr++) {
 146                                 if (curr->type == nh[off]) {
 147                                         /* type specific length/alignment
 148                                            checks will be performed in the
 149                                            func(). */
 150                                         if (curr->func(skb, off) == false)
 151                                                 return false;
 152                                         break;
 153                                 }
 154                         }
 155                         if (curr->type < 0) {
 156                                 if (ip6_tlvopt_unknown(skb, off) == 0)
 157                                         return false;
 158                         }
 159                         padlen = 0;
 160                         break;
 161                 }
 162                 off += optlen;
 163                 len -= optlen;
 164         }
 165
 166         if (len == 0)
 167                 return true;
 168 bad:
 169         kfree_skb(skb);
 170         return false;
 171 }
 172
 173 /*****************************
 174   Destination options header.
 175  *****************************/
 176
 177 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 178 static bool ipv6_dest_hao(struct sk_buff *skb, int optoff)
 179 {
 180         struct ipv6_destopt_hao *hao;
 181         struct inet6_skb_parm *opt = IP6CB(skb);
 182         struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 183         struct in6_addr tmp_addr;
 184         int ret;
 185
 186         if (opt->dsthao) {
 187                 net_dbg_ratelimited("hao duplicated\n");
 188                 goto discard;
 189         }
 190         opt->dsthao = opt->dst1;
 191         opt->dst1 = 0;
 192
 193         hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) + optoff);
 194
 195         if (hao->length != 16) {
 196                 net_dbg_ratelimited("hao invalid option length = %d\n",
 197                                     hao->length);
 198                 goto discard;
 199         }
 200
 201         if (!(ipv6_addr_type(&hao->addr) & IPV6_ADDR_UNICAST)) {
 202                 net_dbg_ratelimited("hao is not an unicast addr: %pI6\n",
 203                                     &hao->addr);
 204                 goto discard;
 205         }
 206
 207         ret = xfrm6_input_addr(skb, (xfrm_address_t *)&ipv6h->daddr,
 208                                (xfrm_address_t *)&hao->addr, IPPROTO_DSTOPTS);
 209         if (unlikely(ret < 0))
 210                 goto discard;
 211
 212         if (skb_cloned(skb)) {
 213                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 214                         goto discard;
 215
 216                 /* update all variable using below by copied skbuff */
 217                 hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) +
 218                                                   optoff);
 219                 ipv6h = ipv6_hdr(skb);
 220         }
 221
 222         if (skb->ip_summed == CHECKSUM_COMPLETE)
 223                 skb->ip_summed = CHECKSUM_NONE;
 224
 225         tmp_addr = ipv6h->saddr;
 226         ipv6h->saddr = hao->addr;
 227         hao->addr = tmp_addr;
 228
 229         if (skb->tstamp.tv64 == 0)
 230                 __net_timestamp(skb);
 231
 232         return true;
 233
 234  discard:
 235         kfree_skb(skb);
 236         return false;
 237 }
 238 #endif
 239
 240 static const struct tlvtype_proc tlvprocdestopt_lst[] = {
 241 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 242         {
 243                 .type   = IPV6_TLV_HAO,
 244                 .func   = ipv6_dest_hao,
 245         },
 246 #endif
 247         {-1,                    NULL}
 248 };
 249
 250 static int ipv6_destopt_rcv(struct sk_buff *skb)
 251 {
 252         struct inet6_skb_parm *opt = IP6CB(skb);
 253 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 254         __u16 dstbuf;
 255 #endif
 256         struct dst_entry *dst = skb_dst(skb);
 257
 258         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 259             !pskb_may_pull(skb, (skb_transport_offset(skb) +
 260                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 261                 IP6_INC_STATS_BH(dev_net(dst->dev), ip6_dst_idev(dst),
 262                                  IPSTATS_MIB_INHDRERRORS);
 263                 kfree_skb(skb);
 264                 return -1;
 265         }
 266
 267         opt->lastopt = opt->dst1 = skb_network_header_len(skb);
 268 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 269         dstbuf = opt->dst1;
 270 #endif
 271
 272         if (ip6_parse_tlv(tlvprocdestopt_lst, skb)) {
 273                 skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
 274                 opt = IP6CB(skb);
 275 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 276                 opt->nhoff = dstbuf;
 277 #else
 278                 opt->nhoff = opt->dst1;
 279 #endif
 280                 return 1;
 281         }
 282
 283         IP6_INC_STATS_BH(dev_net(dst->dev),
 284                          ip6_dst_idev(dst), IPSTATS_MIB_INHDRERRORS);
 285         return -1;
 286 }
 287
 288 /********************************
 289   Routing header.
 290  ********************************/
 291
 292 /* called with rcu_read_lock() */
 293 static int ipv6_rthdr_rcv(struct sk_buff *skb)
 294 {
 295         struct inet6_skb_parm *opt = IP6CB(skb);
 296         struct in6_addr *addr = NULL;
 297         struct in6_addr daddr;
 298         struct inet6_dev *idev;
 299         int n, i;
 300         struct ipv6_rt_hdr *hdr;
 301         struct rt0_hdr *rthdr;
 302         struct net *net = dev_net(skb->dev);
 303         int accept_source_route = net->ipv6.devconf_all->accept_source_route;
 304
 305         idev = __in6_dev_get(skb->dev);
 306         if (idev && accept_source_route > idev->cnf.accept_source_route)
 307                 accept_source_route = idev->cnf.accept_source_route;
 308
 309         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 310             !pskb_may_pull(skb, (skb_transport_offset(skb) +
 311                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 312                 IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 313                                  IPSTATS_MIB_INHDRERRORS);
 314                 kfree_skb(skb);
 315                 return -1;
 316         }
 317
 318         hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 319
 320         if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ||
 321             skb->pkt_type != PACKET_HOST) {
 322                 IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 323                                  IPSTATS_MIB_INADDRERRORS);
 324                 kfree_skb(skb);
 325                 return -1;
 326         }
 327
 328 looped_back:
 329         if (hdr->segments_left == 0) {
 330                 switch (hdr->type) {
 331 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 332                 case IPV6_SRCRT_TYPE_2:
 333                         /* Silently discard type 2 header unless it was
 334                          * processed by own
 335                          */
 336                         if (!addr) {
 337                                 IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 338                                                  IPSTATS_MIB_INADDRERRORS);
 339                                 kfree_skb(skb);
 340                                 return -1;
 341                         }
 342                         break;
 343 #endif
 344                 default:
 345                         break;
 346                 }
 347
 348                 opt->lastopt = opt->srcrt = skb_network_header_len(skb);
 349                 skb->transport_header += (hdr->hdrlen + 1) << 3;
 350                 opt->dst0 = opt->dst1;
 351                 opt->dst1 = 0;
 352                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
 353                 return 1;
 354         }
 355
 356         switch (hdr->type) {
 357 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 358         case IPV6_SRCRT_TYPE_2:
 359                 if (accept_source_route < 0)
 360                         goto unknown_rh;
 361                 /* Silently discard invalid RTH type 2 */
 362                 if (hdr->hdrlen != 2 || hdr->segments_left != 1) {
 363                         IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 364                                          IPSTATS_MIB_INHDRERRORS);
 365                         kfree_skb(skb);
 366                         return -1;
 367                 }
 368                 break;
 369 #endif
 370         default:
 371                 goto unknown_rh;
 372         }
 373
 374         /*
 375          *      This is the routing header forwarding algorithm from
 376          *      RFC 2460, page 16.
 377          */
 378
 379         n = hdr->hdrlen >> 1;
 380
 381         if (hdr->segments_left > n) {
 382                 IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 383                                  IPSTATS_MIB_INHDRERRORS);
 384                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 385                                   ((&hdr->segments_left) -
 386                                    skb_network_header(skb)));
 387                 return -1;
 388         }
 389
 390         /* We are about to mangle packet header. Be careful!
 391            Do not damage packets queued somewhere.
 392          */
 393         if (skb_cloned(skb)) {
 394                 /* the copy is a forwarded packet */
 395                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
 396                         IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 397                                          IPSTATS_MIB_OUTDISCARDS);
 398                         kfree_skb(skb);
 399                         return -1;
 400                 }
 401                 hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 402         }
 403
 404         if (skb->ip_summed == CHECKSUM_COMPLETE)
 405                 skb->ip_summed = CHECKSUM_NONE;
 406
 407         i = n - --hdr->segments_left;
 408
 409         rthdr = (struct rt0_hdr *) hdr;
 410         addr = rthdr->addr;
 411         addr += i - 1;
 412
 413         switch (hdr->type) {
 414 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 415         case IPV6_SRCRT_TYPE_2:
 416                 if (xfrm6_input_addr(skb, (xfrm_address_t *)addr,
 417                                      (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 418                                      IPPROTO_ROUTING) < 0) {
 419                         IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 420                                          IPSTATS_MIB_INADDRERRORS);
 421                         kfree_skb(skb);
 422                         return -1;
 423                 }
 424                 if (!ipv6_chk_home_addr(dev_net(skb_dst(skb)->dev), addr)) {
 425                         IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 426                                          IPSTATS_MIB_INADDRERRORS);
 427                         kfree_skb(skb);
 428                         return -1;
 429                 }
 430                 break;
 431 #endif
 432         default:
 433                 break;
 434         }
 435
 436         if (ipv6_addr_is_multicast(addr)) {
 437                 IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 438                                  IPSTATS_MIB_INADDRERRORS);
 439                 kfree_skb(skb);
 440                 return -1;
 441         }
 442
 443         daddr = *addr;
 444         *addr = ipv6_hdr(skb)->daddr;
 445         ipv6_hdr(skb)->daddr = daddr;
 446
 447         skb_dst_drop(skb);
 448         ip6_route_input(skb);
 449         if (skb_dst(skb)->error) {
 450                 skb_push(skb, skb->data - skb_network_header(skb));
 451                 dst_input(skb);
 452                 return -1;
 453         }
 454
 455         if (skb_dst(skb)->dev->flags&IFF_LOOPBACK) {
 456                 if (ipv6_hdr(skb)->hop_limit <= 1) {
 457                         IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 458                                          IPSTATS_MIB_INHDRERRORS);
 459                         icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
 460                                     0);
 461                         kfree_skb(skb);
 462                         return -1;
 463                 }
 464                 ipv6_hdr(skb)->hop_limit--;
 465                 goto looped_back;
 466         }
 467
 468         skb_push(skb, skb->data - skb_network_header(skb));
 469         dst_input(skb);
 470         return -1;
 471
 472 unknown_rh:
 473         IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS);
 474         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 475                           (&hdr->type) - skb_network_header(skb));
 476         return -1;
 477 }
 478
 479 static const struct inet6_protocol rthdr_protocol = {
 480         .handler        =       ipv6_rthdr_rcv,
 481         .flags          =       INET6_PROTO_NOPOLICY,
 482 };
 483
 484 static const struct inet6_protocol destopt_protocol = {
 485         .handler        =       ipv6_destopt_rcv,
 486         .flags          =       INET6_PROTO_NOPOLICY,
 487 };
 488
 489 static const struct inet6_protocol nodata_protocol = {
 490         .handler        =       dst_discard,
 491         .flags          =       INET6_PROTO_NOPOLICY,
 492 };
 493
 494 int __init ipv6_exthdrs_init(void)
 495 {
 496         int ret;
 497
 498         ret = inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 499         if (ret)
 500                 goto out;
 501
 502         ret = inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 503         if (ret)
 504                 goto out_rthdr;
 505
 506         ret = inet6_add_protocol(&nodata_protocol, IPPROTO_NONE);
 507         if (ret)
 508                 goto out_destopt;
 509
 510 out:
 511         return ret;
 512 out_destopt:
 513         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 514 out_rthdr:
 515         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 516         goto out;
 517 };
 518
 519 void ipv6_exthdrs_exit(void)
 520 {
 521         inet6_del_protocol(&nodata_protocol, IPPROTO_NONE);
 522         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 523         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 524 }
 525
 526 /**********************************
 527   Hop-by-hop options.
 528  **********************************/
 529
 530 /*
 531  * Note: we cannot rely on skb_dst(skb) before we assign it in ip6_route_input().
 532  */
 533 static inline struct inet6_dev *ipv6_skb_idev(struct sk_buff *skb)
 534 {
 535         return skb_dst(skb) ? ip6_dst_idev(skb_dst(skb)) : __in6_dev_get(skb->dev);
 536 }
 537
 538 static inline struct net *ipv6_skb_net(struct sk_buff *skb)
 539 {
 540         return skb_dst(skb) ? dev_net(skb_dst(skb)->dev) : dev_net(skb->dev);
 541 }
 542
 543 /* Router Alert as of RFC 2711 */
 544
 545 static bool ipv6_hop_ra(struct sk_buff *skb, int optoff)
 546 {
 547         const unsigned char *nh = skb_network_header(skb);
 548
 549         if (nh[optoff + 1] == 2) {
 550                 IP6CB(skb)->flags |= IP6SKB_ROUTERALERT;
 551                 memcpy(&IP6CB(skb)->ra, nh + optoff + 2, sizeof(IP6CB(skb)->ra));
 552                 return true;
 553         }
 554         net_dbg_ratelimited("ipv6_hop_ra: wrong RA length %d\n",
 555                             nh[optoff + 1]);
 556         kfree_skb(skb);
 557         return false;
 558 }
 559
 560 /* Jumbo payload */
 561
 562 static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
 563 {
 564         const unsigned char *nh = skb_network_header(skb);
 565         struct net *net = ipv6_skb_net(skb);
 566         u32 pkt_len;
 567
 568         if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
 569                 net_dbg_ratelimited("ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
 570                                     nh[optoff+1]);
 571                 IP6_INC_STATS_BH(net, ipv6_skb_idev(skb),
 572                                  IPSTATS_MIB_INHDRERRORS);
 573                 goto drop;
 574         }
 575
 576         pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
 577         if (pkt_len <= IPV6_MAXPLEN) {
 578                 IP6_INC_STATS_BH(net, ipv6_skb_idev(skb),
 579                                  IPSTATS_MIB_INHDRERRORS);
 580                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2);
 581                 return false;
 582         }
 583         if (ipv6_hdr(skb)->payload_len) {
 584                 IP6_INC_STATS_BH(net, ipv6_skb_idev(skb),
 585                                  IPSTATS_MIB_INHDRERRORS);
 586                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff);
 587                 return false;
 588         }
 589
 590         if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
 591                 IP6_INC_STATS_BH(net, ipv6_skb_idev(skb),
 592                                  IPSTATS_MIB_INTRUNCATEDPKTS);
 593                 goto drop;
 594         }
 595
 596         if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 597                 goto drop;
 598
 599         return true;
 600
 601 drop:
 602         kfree_skb(skb);
 603         return false;
 604 }
 605
 606 static const struct tlvtype_proc tlvprochopopt_lst[] = {
 607         {
 608                 .type   = IPV6_TLV_ROUTERALERT,
 609                 .func   = ipv6_hop_ra,
 610         },
 611         {
 612                 .type   = IPV6_TLV_JUMBO,
 613                 .func   = ipv6_hop_jumbo,
 614         },
 615         { -1, }
 616 };
 617
 618 int ipv6_parse_hopopts(struct sk_buff *skb)
 619 {
 620         struct inet6_skb_parm *opt = IP6CB(skb);
 621
 622         /*
 623          * skb_network_header(skb) is equal to skb->data, and
 624          * skb_network_header_len(skb) is always equal to
 625          * sizeof(struct ipv6hdr) by definition of
 626          * hop-by-hop options.
 627          */
 628         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
 629             !pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
 630                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 631                 kfree_skb(skb);
 632                 return -1;
 633         }
 634
 635         opt->hop = sizeof(struct ipv6hdr);
 636         if (ip6_parse_tlv(tlvprochopopt_lst, skb)) {
 637                 skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
 638                 opt = IP6CB(skb);
 639                 opt->nhoff = sizeof(struct ipv6hdr);
 640                 return 1;
 641         }
 642         return -1;
 643 }
 644
 645 /*
 646  *      Creating outbound headers.
 647  *
 648  *      "build" functions work when skb is filled from head to tail (datagram)
 649  *      "push"  functions work when headers are added from tail to head (tcp)
 650  *
 651  *      In both cases we assume, that caller reserved enough room
 652  *      for headers.
 653  */
 654
 655 static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
 656                             struct ipv6_rt_hdr *opt,
 657                             struct in6_addr **addr_p)
 658 {
 659         struct rt0_hdr *phdr, *ihdr;
 660         int hops;
 661
 662         ihdr = (struct rt0_hdr *) opt;
 663
 664         phdr = (struct rt0_hdr *) skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
 665         memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
 666
 667         hops = ihdr->rt_hdr.hdrlen >> 1;
 668
 669         if (hops > 1)
 670                 memcpy(phdr->addr, ihdr->addr + 1,
 671                        (hops - 1) * sizeof(struct in6_addr));
 672
 673         phdr->addr[hops - 1] = **addr_p;
 674         *addr_p = ihdr->addr;
 675
 676         phdr->rt_hdr.nexthdr = *proto;
 677         *proto = NEXTHDR_ROUTING;
 678 }
 679
 680 static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
 681 {
 682         struct ipv6_opt_hdr *h = (struct ipv6_opt_hdr *)skb_push(skb, ipv6_optlen(opt));
 683
 684         memcpy(h, opt, ipv6_optlen(opt));
 685         h->nexthdr = *proto;
 686         *proto = type;
 687 }
 688
 689 void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
 690                           u8 *proto,
 691                           struct in6_addr **daddr)
 692 {
 693         if (opt->srcrt) {
 694                 ipv6_push_rthdr(skb, proto, opt->srcrt, daddr);
 695                 /*
 696                  * IPV6_RTHDRDSTOPTS is ignored
 697                  * unless IPV6_RTHDR is set (RFC3542).
 698                  */
 699                 if (opt->dst0opt)
 700                         ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
 701         }
 702         if (opt->hopopt)
 703                 ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
 704 }
 705 EXPORT_SYMBOL(ipv6_push_nfrag_opts);
 706
 707 void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
 708 {
 709         if (opt->dst1opt)
 710                 ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
 711 }
 712
 713 struct ipv6_txoptions *
 714 ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
 715 {
 716         struct ipv6_txoptions *opt2;
 717
 718         opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
 719         if (opt2) {
 720                 long dif = (char *)opt2 - (char *)opt;
 721                 memcpy(opt2, opt, opt->tot_len);
 722                 if (opt2->hopopt)
 723                         *((char **)&opt2->hopopt) += dif;
 724                 if (opt2->dst0opt)
 725                         *((char **)&opt2->dst0opt) += dif;
 726                 if (opt2->dst1opt)
 727                         *((char **)&opt2->dst1opt) += dif;
 728                 if (opt2->srcrt)
 729                         *((char **)&opt2->srcrt) += dif;
 730         }
 731         return opt2;
 732 }
 733 EXPORT_SYMBOL_GPL(ipv6_dup_options);
 734
 735 static int ipv6_renew_option(void *ohdr,
 736                              struct ipv6_opt_hdr __user *newopt, int newoptlen,
 737                              int inherit,
 738                              struct ipv6_opt_hdr **hdr,
 739                              char **p)
 740 {
 741         if (inherit) {
 742                 if (ohdr) {
 743                         memcpy(*p, ohdr, ipv6_optlen((struct ipv6_opt_hdr *)ohdr));
 744                         *hdr = (struct ipv6_opt_hdr *)*p;
 745                         *p += CMSG_ALIGN(ipv6_optlen(*hdr));
 746                 }
 747         } else {
 748                 if (newopt) {
 749                         if (copy_from_user(*p, newopt, newoptlen))
 750                                 return -EFAULT;
 751                         *hdr = (struct ipv6_opt_hdr *)*p;
 752                         if (ipv6_optlen(*hdr) > newoptlen)
 753                                 return -EINVAL;
 754                         *p += CMSG_ALIGN(newoptlen);
 755                 }
 756         }
 757         return 0;
 758 }
 759
 760 struct ipv6_txoptions *
 761 ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
 762                    int newtype,
 763                    struct ipv6_opt_hdr __user *newopt, int newoptlen)
 764 {
 765         int tot_len = 0;
 766         char *p;
 767         struct ipv6_txoptions *opt2;
 768         int err;
 769
 770         if (opt) {
 771                 if (newtype != IPV6_HOPOPTS && opt->hopopt)
 772                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
 773                 if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
 774                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
 775                 if (newtype != IPV6_RTHDR && opt->srcrt)
 776                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
 777                 if (newtype != IPV6_DSTOPTS && opt->dst1opt)
 778                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
 779         }
 780
 781         if (newopt && newoptlen)
 782                 tot_len += CMSG_ALIGN(newoptlen);
 783
 784         if (!tot_len)
 785                 return NULL;
 786
 787         tot_len += sizeof(*opt2);
 788         opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
 789         if (!opt2)
 790                 return ERR_PTR(-ENOBUFS);
 791
 792         memset(opt2, 0, tot_len);
 793
 794         opt2->tot_len = tot_len;
 795         p = (char *)(opt2 + 1);
 796
 797         err = ipv6_renew_option(opt ? opt->hopopt : NULL, newopt, newoptlen,
 798                                 newtype != IPV6_HOPOPTS,
 799                                 &opt2->hopopt, &p);
 800         if (err)
 801                 goto out;
 802
 803         err = ipv6_renew_option(opt ? opt->dst0opt : NULL, newopt, newoptlen,
 804                                 newtype != IPV6_RTHDRDSTOPTS,
 805                                 &opt2->dst0opt, &p);
 806         if (err)
 807                 goto out;
 808
 809         err = ipv6_renew_option(opt ? opt->srcrt : NULL, newopt, newoptlen,
 810                                 newtype != IPV6_RTHDR,
 811                                 (struct ipv6_opt_hdr **)&opt2->srcrt, &p);
 812         if (err)
 813                 goto out;
 814
 815         err = ipv6_renew_option(opt ? opt->dst1opt : NULL, newopt, newoptlen,
 816                                 newtype != IPV6_DSTOPTS,
 817                                 &opt2->dst1opt, &p);
 818         if (err)
 819                 goto out;
 820
 821         opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
 822                           (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
 823                           (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
 824         opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
 825
 826         return opt2;
 827 out:
 828         sock_kfree_s(sk, opt2, opt2->tot_len);
 829         return ERR_PTR(err);
 830 }
 831
 832 struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space,
 833                                           struct ipv6_txoptions *opt)
 834 {
 835         /*
 836          * ignore the dest before srcrt unless srcrt is being included.
 837          * --yoshfuji
 838          */
 839         if (opt && opt->dst0opt && !opt->srcrt) {
 840                 if (opt_space != opt) {
 841                         memcpy(opt_space, opt, sizeof(*opt_space));
 842                         opt = opt_space;
 843                 }
 844                 opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
 845                 opt->dst0opt = NULL;
 846         }
 847
 848         return opt;
 849 }
 850 EXPORT_SYMBOL_GPL(ipv6_fixup_options);
 851
 852 /**
 853  * fl6_update_dst - update flowi destination address with info given
 854  *                  by srcrt option, if any.
 855  *
 856  * @fl6: flowi6 for which daddr is to be updated
 857  * @opt: struct ipv6_txoptions in which to look for srcrt opt
 858  * @orig: copy of original daddr address if modified
 859  *
 860  * Returns NULL if no txoptions or no srcrt, otherwise returns orig
 861  * and initial value of fl6->daddr set in orig
 862  */
 863 struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
 864                                 const struct ipv6_txoptions *opt,
 865                                 struct in6_addr *orig)
 866 {
 867         if (!opt || !opt->srcrt)
 868                 return NULL;
 869
 870         *orig = fl6->daddr;
 871         fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr;
 872         return orig;
 873 }
 874 EXPORT_SYMBOL_GPL(fl6_update_dst);