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 <asm/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         /* This case will not be caught by above check since its padding
 166          * length is smaller than 7:
 167          * 1 byte NH + 1 byte Length + 6 bytes Padding
 168          */
 169         if ((padlen == 6) && ((off - skb_network_header_len(skb)) == 8))
 170                 goto bad;
 171
 172         if (len == 0)
 173                 return true;
 174 bad:
 175         kfree_skb(skb);
 176         return false;
 177 }
 178
 179 /*****************************
 180   Destination options header.
 181  *****************************/
 182
 183 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 184 static bool ipv6_dest_hao(struct sk_buff *skb, int optoff)
 185 {
 186         struct ipv6_destopt_hao *hao;
 187         struct inet6_skb_parm *opt = IP6CB(skb);
 188         struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 189         struct in6_addr tmp_addr;
 190         int ret;
 191
 192         if (opt->dsthao) {
 193                 LIMIT_NETDEBUG(KERN_DEBUG "hao duplicated\n");
 194                 goto discard;
 195         }
 196         opt->dsthao = opt->dst1;
 197         opt->dst1 = 0;
 198
 199         hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) + optoff);
 200
 201         if (hao->length != 16) {
 202                 LIMIT_NETDEBUG(
 203                         KERN_DEBUG "hao invalid option length = %d\n", hao->length);
 204                 goto discard;
 205         }
 206
 207         if (!(ipv6_addr_type(&hao->addr) & IPV6_ADDR_UNICAST)) {
 208                 LIMIT_NETDEBUG(
 209                         KERN_DEBUG "hao is not an unicast addr: %pI6\n", &hao->addr);
 210                 goto discard;
 211         }
 212
 213         ret = xfrm6_input_addr(skb, (xfrm_address_t *)&ipv6h->daddr,
 214                                (xfrm_address_t *)&hao->addr, IPPROTO_DSTOPTS);
 215         if (unlikely(ret < 0))
 216                 goto discard;
 217
 218         if (skb_cloned(skb)) {
 219                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 220                         goto discard;
 221
 222                 /* update all variable using below by copied skbuff */
 223                 hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) +
 224                                                   optoff);
 225                 ipv6h = ipv6_hdr(skb);
 226         }
 227
 228         if (skb->ip_summed == CHECKSUM_COMPLETE)
 229                 skb->ip_summed = CHECKSUM_NONE;
 230
 231         tmp_addr = ipv6h->saddr;
 232         ipv6h->saddr = hao->addr;
 233         hao->addr = tmp_addr;
 234
 235         if (skb->tstamp.tv64 == 0)
 236                 __net_timestamp(skb);
 237
 238         return true;
 239
 240  discard:
 241         kfree_skb(skb);
 242         return false;
 243 }
 244 #endif
 245
 246 static const struct tlvtype_proc tlvprocdestopt_lst[] = {
 247 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 248         {
 249                 .type   = IPV6_TLV_HAO,
 250                 .func   = ipv6_dest_hao,
 251         },
 252 #endif
 253         {-1,                    NULL}
 254 };
 255
 256 static int ipv6_destopt_rcv(struct sk_buff *skb)
 257 {
 258         struct inet6_skb_parm *opt = IP6CB(skb);
 259 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 260         __u16 dstbuf;
 261 #endif
 262         struct dst_entry *dst = skb_dst(skb);
 263
 264         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 265             !pskb_may_pull(skb, (skb_transport_offset(skb) +
 266                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 267                 IP6_INC_STATS_BH(dev_net(dst->dev), ip6_dst_idev(dst),
 268                                  IPSTATS_MIB_INHDRERRORS);
 269                 kfree_skb(skb);
 270                 return -1;
 271         }
 272
 273         opt->lastopt = opt->dst1 = skb_network_header_len(skb);
 274 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 275         dstbuf = opt->dst1;
 276 #endif
 277
 278         if (ip6_parse_tlv(tlvprocdestopt_lst, skb)) {
 279                 skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
 280                 opt = IP6CB(skb);
 281 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 282                 opt->nhoff = dstbuf;
 283 #else
 284                 opt->nhoff = opt->dst1;
 285 #endif
 286                 return 1;
 287         }
 288
 289         IP6_INC_STATS_BH(dev_net(dst->dev),
 290                          ip6_dst_idev(dst), IPSTATS_MIB_INHDRERRORS);
 291         return -1;
 292 }
 293
 294 /********************************
 295   Routing header.
 296  ********************************/
 297
 298 /* called with rcu_read_lock() */
 299 static int ipv6_rthdr_rcv(struct sk_buff *skb)
 300 {
 301         struct inet6_skb_parm *opt = IP6CB(skb);
 302         struct in6_addr *addr = NULL;
 303         struct in6_addr daddr;
 304         struct inet6_dev *idev;
 305         int n, i;
 306         struct ipv6_rt_hdr *hdr;
 307         struct rt0_hdr *rthdr;
 308         struct net *net = dev_net(skb->dev);
 309         int accept_source_route = net->ipv6.devconf_all->accept_source_route;
 310
 311         idev = __in6_dev_get(skb->dev);
 312         if (idev && accept_source_route > idev->cnf.accept_source_route)
 313                 accept_source_route = idev->cnf.accept_source_route;
 314
 315         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 316             !pskb_may_pull(skb, (skb_transport_offset(skb) +
 317                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 318                 IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 319                                  IPSTATS_MIB_INHDRERRORS);
 320                 kfree_skb(skb);
 321                 return -1;
 322         }
 323
 324         hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 325
 326         if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ||
 327             skb->pkt_type != PACKET_HOST) {
 328                 IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 329                                  IPSTATS_MIB_INADDRERRORS);
 330                 kfree_skb(skb);
 331                 return -1;
 332         }
 333
 334 looped_back:
 335         if (hdr->segments_left == 0) {
 336                 switch (hdr->type) {
 337 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 338                 case IPV6_SRCRT_TYPE_2:
 339                         /* Silently discard type 2 header unless it was
 340                          * processed by own
 341                          */
 342                         if (!addr) {
 343                                 IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 344                                                  IPSTATS_MIB_INADDRERRORS);
 345                                 kfree_skb(skb);
 346                                 return -1;
 347                         }
 348                         break;
 349 #endif
 350                 default:
 351                         break;
 352                 }
 353
 354                 opt->lastopt = opt->srcrt = skb_network_header_len(skb);
 355                 skb->transport_header += (hdr->hdrlen + 1) << 3;
 356                 opt->dst0 = opt->dst1;
 357                 opt->dst1 = 0;
 358                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
 359                 return 1;
 360         }
 361
 362         switch (hdr->type) {
 363 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 364         case IPV6_SRCRT_TYPE_2:
 365                 if (accept_source_route < 0)
 366                         goto unknown_rh;
 367                 /* Silently discard invalid RTH type 2 */
 368                 if (hdr->hdrlen != 2 || hdr->segments_left != 1) {
 369                         IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 370                                          IPSTATS_MIB_INHDRERRORS);
 371                         kfree_skb(skb);
 372                         return -1;
 373                 }
 374                 break;
 375 #endif
 376         default:
 377                 goto unknown_rh;
 378         }
 379
 380         /*
 381          *      This is the routing header forwarding algorithm from
 382          *      RFC 2460, page 16.
 383          */
 384
 385         n = hdr->hdrlen >> 1;
 386
 387         if (hdr->segments_left > n) {
 388                 IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 389                                  IPSTATS_MIB_INHDRERRORS);
 390                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 391                                   ((&hdr->segments_left) -
 392                                    skb_network_header(skb)));
 393                 return -1;
 394         }
 395
 396         /* We are about to mangle packet header. Be careful!
 397            Do not damage packets queued somewhere.
 398          */
 399         if (skb_cloned(skb)) {
 400                 /* the copy is a forwarded packet */
 401                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
 402                         IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 403                                          IPSTATS_MIB_OUTDISCARDS);
 404                         kfree_skb(skb);
 405                         return -1;
 406                 }
 407                 hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 408         }
 409
 410         if (skb->ip_summed == CHECKSUM_COMPLETE)
 411                 skb->ip_summed = CHECKSUM_NONE;
 412
 413         i = n - --hdr->segments_left;
 414
 415         rthdr = (struct rt0_hdr *) hdr;
 416         addr = rthdr->addr;
 417         addr += i - 1;
 418
 419         switch (hdr->type) {
 420 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 421         case IPV6_SRCRT_TYPE_2:
 422                 if (xfrm6_input_addr(skb, (xfrm_address_t *)addr,
 423                                      (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 424                                      IPPROTO_ROUTING) < 0) {
 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                 if (!ipv6_chk_home_addr(dev_net(skb_dst(skb)->dev), addr)) {
 431                         IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 432                                          IPSTATS_MIB_INADDRERRORS);
 433                         kfree_skb(skb);
 434                         return -1;
 435                 }
 436                 break;
 437 #endif
 438         default:
 439                 break;
 440         }
 441
 442         if (ipv6_addr_is_multicast(addr)) {
 443                 IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 444                                  IPSTATS_MIB_INADDRERRORS);
 445                 kfree_skb(skb);
 446                 return -1;
 447         }
 448
 449         daddr = *addr;
 450         *addr = ipv6_hdr(skb)->daddr;
 451         ipv6_hdr(skb)->daddr = daddr;
 452
 453         skb_dst_drop(skb);
 454         ip6_route_input(skb);
 455         if (skb_dst(skb)->error) {
 456                 skb_push(skb, skb->data - skb_network_header(skb));
 457                 dst_input(skb);
 458                 return -1;
 459         }
 460
 461         if (skb_dst(skb)->dev->flags&IFF_LOOPBACK) {
 462                 if (ipv6_hdr(skb)->hop_limit <= 1) {
 463                         IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 464                                          IPSTATS_MIB_INHDRERRORS);
 465                         icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
 466                                     0);
 467                         kfree_skb(skb);
 468                         return -1;
 469                 }
 470                 ipv6_hdr(skb)->hop_limit--;
 471                 goto looped_back;
 472         }
 473
 474         skb_push(skb, skb->data - skb_network_header(skb));
 475         dst_input(skb);
 476         return -1;
 477
 478 unknown_rh:
 479         IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS);
 480         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 481                           (&hdr->type) - skb_network_header(skb));
 482         return -1;
 483 }
 484
 485 static const struct inet6_protocol rthdr_protocol = {
 486         .handler        =       ipv6_rthdr_rcv,
 487         .flags          =       INET6_PROTO_NOPOLICY,
 488 };
 489
 490 static const struct inet6_protocol destopt_protocol = {
 491         .handler        =       ipv6_destopt_rcv,
 492         .flags          =       INET6_PROTO_NOPOLICY,
 493 };
 494
 495 static const struct inet6_protocol nodata_protocol = {
 496         .handler        =       dst_discard,
 497         .flags          =       INET6_PROTO_NOPOLICY,
 498 };
 499
 500 int __init ipv6_exthdrs_init(void)
 501 {
 502         int ret;
 503
 504         ret = inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 505         if (ret)
 506                 goto out;
 507
 508         ret = inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 509         if (ret)
 510                 goto out_rthdr;
 511
 512         ret = inet6_add_protocol(&nodata_protocol, IPPROTO_NONE);
 513         if (ret)
 514                 goto out_destopt;
 515
 516 out:
 517         return ret;
 518 out_destopt:
 519         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 520 out_rthdr:
 521         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 522         goto out;
 523 };
 524
 525 void ipv6_exthdrs_exit(void)
 526 {
 527         inet6_del_protocol(&nodata_protocol, IPPROTO_NONE);
 528         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 529         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 530 }
 531
 532 /**********************************
 533   Hop-by-hop options.
 534  **********************************/
 535
 536 /*
 537  * Note: we cannot rely on skb_dst(skb) before we assign it in ip6_route_input().
 538  */
 539 static inline struct inet6_dev *ipv6_skb_idev(struct sk_buff *skb)
 540 {
 541         return skb_dst(skb) ? ip6_dst_idev(skb_dst(skb)) : __in6_dev_get(skb->dev);
 542 }
 543
 544 static inline struct net *ipv6_skb_net(struct sk_buff *skb)
 545 {
 546         return skb_dst(skb) ? dev_net(skb_dst(skb)->dev) : dev_net(skb->dev);
 547 }
 548
 549 /* Router Alert as of RFC 2711 */
 550
 551 static bool ipv6_hop_ra(struct sk_buff *skb, int optoff)
 552 {
 553         const unsigned char *nh = skb_network_header(skb);
 554
 555         if (nh[optoff + 1] == 2) {
 556                 IP6CB(skb)->ra = optoff;
 557                 return true;
 558         }
 559         LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_ra: wrong RA length %d\n",
 560                        nh[optoff + 1]);
 561         kfree_skb(skb);
 562         return false;
 563 }
 564
 565 /* Jumbo payload */
 566
 567 static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
 568 {
 569         const unsigned char *nh = skb_network_header(skb);
 570         struct net *net = ipv6_skb_net(skb);
 571         u32 pkt_len;
 572
 573         if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
 574                 LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
 575                                nh[optoff+1]);
 576                 IP6_INC_STATS_BH(net, ipv6_skb_idev(skb),
 577                                  IPSTATS_MIB_INHDRERRORS);
 578                 goto drop;
 579         }
 580
 581         pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
 582         if (pkt_len <= IPV6_MAXPLEN) {
 583                 IP6_INC_STATS_BH(net, ipv6_skb_idev(skb),
 584                                  IPSTATS_MIB_INHDRERRORS);
 585                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2);
 586                 return false;
 587         }
 588         if (ipv6_hdr(skb)->payload_len) {
 589                 IP6_INC_STATS_BH(net, ipv6_skb_idev(skb),
 590                                  IPSTATS_MIB_INHDRERRORS);
 591                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff);
 592                 return false;
 593         }
 594
 595         if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
 596                 IP6_INC_STATS_BH(net, ipv6_skb_idev(skb),
 597                                  IPSTATS_MIB_INTRUNCATEDPKTS);
 598                 goto drop;
 599         }
 600
 601         if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 602                 goto drop;
 603
 604         return true;
 605
 606 drop:
 607         kfree_skb(skb);
 608         return false;
 609 }
 610
 611 static const struct tlvtype_proc tlvprochopopt_lst[] = {
 612         {
 613                 .type   = IPV6_TLV_ROUTERALERT,
 614                 .func   = ipv6_hop_ra,
 615         },
 616         {
 617                 .type   = IPV6_TLV_JUMBO,
 618                 .func   = ipv6_hop_jumbo,
 619         },
 620         { -1, }
 621 };
 622
 623 int ipv6_parse_hopopts(struct sk_buff *skb)
 624 {
 625         struct inet6_skb_parm *opt = IP6CB(skb);
 626
 627         /*
 628          * skb_network_header(skb) is equal to skb->data, and
 629          * skb_network_header_len(skb) is always equal to
 630          * sizeof(struct ipv6hdr) by definition of
 631          * hop-by-hop options.
 632          */
 633         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
 634             !pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
 635                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 636                 kfree_skb(skb);
 637                 return -1;
 638         }
 639
 640         opt->hop = sizeof(struct ipv6hdr);
 641         if (ip6_parse_tlv(tlvprochopopt_lst, skb)) {
 642                 skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
 643                 opt = IP6CB(skb);
 644                 opt->nhoff = sizeof(struct ipv6hdr);
 645                 return 1;
 646         }
 647         return -1;
 648 }
 649
 650 /*
 651  *      Creating outbound headers.
 652  *
 653  *      "build" functions work when skb is filled from head to tail (datagram)
 654  *      "push"  functions work when headers are added from tail to head (tcp)
 655  *
 656  *      In both cases we assume, that caller reserved enough room
 657  *      for headers.
 658  */
 659
 660 static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
 661                             struct ipv6_rt_hdr *opt,
 662                             struct in6_addr **addr_p)
 663 {
 664         struct rt0_hdr *phdr, *ihdr;
 665         int hops;
 666
 667         ihdr = (struct rt0_hdr *) opt;
 668
 669         phdr = (struct rt0_hdr *) skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
 670         memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
 671
 672         hops = ihdr->rt_hdr.hdrlen >> 1;
 673
 674         if (hops > 1)
 675                 memcpy(phdr->addr, ihdr->addr + 1,
 676                        (hops - 1) * sizeof(struct in6_addr));
 677
 678         phdr->addr[hops - 1] = **addr_p;
 679         *addr_p = ihdr->addr;
 680
 681         phdr->rt_hdr.nexthdr = *proto;
 682         *proto = NEXTHDR_ROUTING;
 683 }
 684
 685 static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
 686 {
 687         struct ipv6_opt_hdr *h = (struct ipv6_opt_hdr *)skb_push(skb, ipv6_optlen(opt));
 688
 689         memcpy(h, opt, ipv6_optlen(opt));
 690         h->nexthdr = *proto;
 691         *proto = type;
 692 }
 693
 694 void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
 695                           u8 *proto,
 696                           struct in6_addr **daddr)
 697 {
 698         if (opt->srcrt) {
 699                 ipv6_push_rthdr(skb, proto, opt->srcrt, daddr);
 700                 /*
 701                  * IPV6_RTHDRDSTOPTS is ignored
 702                  * unless IPV6_RTHDR is set (RFC3542).
 703                  */
 704                 if (opt->dst0opt)
 705                         ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
 706         }
 707         if (opt->hopopt)
 708                 ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
 709 }
 710 EXPORT_SYMBOL(ipv6_push_nfrag_opts);
 711
 712 void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
 713 {
 714         if (opt->dst1opt)
 715                 ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
 716 }
 717
 718 struct ipv6_txoptions *
 719 ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
 720 {
 721         struct ipv6_txoptions *opt2;
 722
 723         opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
 724         if (opt2) {
 725                 long dif = (char *)opt2 - (char *)opt;
 726                 memcpy(opt2, opt, opt->tot_len);
 727                 if (opt2->hopopt)
 728                         *((char **)&opt2->hopopt) += dif;
 729                 if (opt2->dst0opt)
 730                         *((char **)&opt2->dst0opt) += dif;
 731                 if (opt2->dst1opt)
 732                         *((char **)&opt2->dst1opt) += dif;
 733                 if (opt2->srcrt)
 734                         *((char **)&opt2->srcrt) += dif;
 735         }
 736         return opt2;
 737 }
 738 EXPORT_SYMBOL_GPL(ipv6_dup_options);
 739
 740 static int ipv6_renew_option(void *ohdr,
 741                              struct ipv6_opt_hdr __user *newopt, int newoptlen,
 742                              int inherit,
 743                              struct ipv6_opt_hdr **hdr,
 744                              char **p)
 745 {
 746         if (inherit) {
 747                 if (ohdr) {
 748                         memcpy(*p, ohdr, ipv6_optlen((struct ipv6_opt_hdr *)ohdr));
 749                         *hdr = (struct ipv6_opt_hdr *)*p;
 750                         *p += CMSG_ALIGN(ipv6_optlen(*hdr));
 751                 }
 752         } else {
 753                 if (newopt) {
 754                         if (copy_from_user(*p, newopt, newoptlen))
 755                                 return -EFAULT;
 756                         *hdr = (struct ipv6_opt_hdr *)*p;
 757                         if (ipv6_optlen(*hdr) > newoptlen)
 758                                 return -EINVAL;
 759                         *p += CMSG_ALIGN(newoptlen);
 760                 }
 761         }
 762         return 0;
 763 }
 764
 765 struct ipv6_txoptions *
 766 ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
 767                    int newtype,
 768                    struct ipv6_opt_hdr __user *newopt, int newoptlen)
 769 {
 770         int tot_len = 0;
 771         char *p;
 772         struct ipv6_txoptions *opt2;
 773         int err;
 774
 775         if (opt) {
 776                 if (newtype != IPV6_HOPOPTS && opt->hopopt)
 777                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
 778                 if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
 779                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
 780                 if (newtype != IPV6_RTHDR && opt->srcrt)
 781                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
 782                 if (newtype != IPV6_DSTOPTS && opt->dst1opt)
 783                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
 784         }
 785
 786         if (newopt && newoptlen)
 787                 tot_len += CMSG_ALIGN(newoptlen);
 788
 789         if (!tot_len)
 790                 return NULL;
 791
 792         tot_len += sizeof(*opt2);
 793         opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
 794         if (!opt2)
 795                 return ERR_PTR(-ENOBUFS);
 796
 797         memset(opt2, 0, tot_len);
 798
 799         opt2->tot_len = tot_len;
 800         p = (char *)(opt2 + 1);
 801
 802         err = ipv6_renew_option(opt ? opt->hopopt : NULL, newopt, newoptlen,
 803                                 newtype != IPV6_HOPOPTS,
 804                                 &opt2->hopopt, &p);
 805         if (err)
 806                 goto out;
 807
 808         err = ipv6_renew_option(opt ? opt->dst0opt : NULL, newopt, newoptlen,
 809                                 newtype != IPV6_RTHDRDSTOPTS,
 810                                 &opt2->dst0opt, &p);
 811         if (err)
 812                 goto out;
 813
 814         err = ipv6_renew_option(opt ? opt->srcrt : NULL, newopt, newoptlen,
 815                                 newtype != IPV6_RTHDR,
 816                                 (struct ipv6_opt_hdr **)&opt2->srcrt, &p);
 817         if (err)
 818                 goto out;
 819
 820         err = ipv6_renew_option(opt ? opt->dst1opt : NULL, newopt, newoptlen,
 821                                 newtype != IPV6_DSTOPTS,
 822                                 &opt2->dst1opt, &p);
 823         if (err)
 824                 goto out;
 825
 826         opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
 827                           (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
 828                           (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
 829         opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
 830
 831         return opt2;
 832 out:
 833         sock_kfree_s(sk, opt2, opt2->tot_len);
 834         return ERR_PTR(err);
 835 }
 836
 837 struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space,
 838                                           struct ipv6_txoptions *opt)
 839 {
 840         /*
 841          * ignore the dest before srcrt unless srcrt is being included.
 842          * --yoshfuji
 843          */
 844         if (opt && opt->dst0opt && !opt->srcrt) {
 845                 if (opt_space != opt) {
 846                         memcpy(opt_space, opt, sizeof(*opt_space));
 847                         opt = opt_space;
 848                 }
 849                 opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
 850                 opt->dst0opt = NULL;
 851         }
 852
 853         return opt;
 854 }
 855 EXPORT_SYMBOL_GPL(ipv6_fixup_options);
 856
 857 /**
 858  * fl6_update_dst - update flowi destination address with info given
 859  *                  by srcrt option, if any.
 860  *
 861  * @fl6: flowi6 for which daddr is to be updated
 862  * @opt: struct ipv6_txoptions in which to look for srcrt opt
 863  * @orig: copy of original daddr address if modified
 864  *
 865  * Returns NULL if no txoptions or no srcrt, otherwise returns orig
 866  * and initial value of fl6->daddr set in orig
 867  */
 868 struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
 869                                 const struct ipv6_txoptions *opt,
 870                                 struct in6_addr *orig)
 871 {
 872         if (!opt || !opt->srcrt)
 873                 return NULL;
 874
 875         *orig = fl6->daddr;
 876         fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr;
 877         return orig;
 878 }
 879 EXPORT_SYMBOL_GPL(fl6_update_dst);