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  *      $Id: exthdrs.c,v 1.13 2001/06/19 15:58:56 davem Exp $
  11  *
  12  *      This program is free software; you can redistribute it and/or
  13  *      modify it under the terms of the GNU General Public License
  14  *      as published by the Free Software Foundation; either version
  15  *      2 of the License, or (at your option) any later version.
  16  */
  17
  18 /* Changes:
  19  *      yoshfuji                : ensure not to overrun while parsing
  20  *                                tlv options.
  21  *      Mitsuru KANDA @USAGI and: Remove ipv6_parse_exthdrs().
  22  *      YOSHIFUJI Hideaki @USAGI  Register inbound extension header
  23  *                                handlers as inet6_protocol{}.
  24  */
  25
  26 #include <linux/errno.h>
  27 #include <linux/types.h>
  28 #include <linux/socket.h>
  29 #include <linux/sockios.h>
  30 #include <linux/net.h>
  31 #include <linux/netdevice.h>
  32 #include <linux/in6.h>
  33 #include <linux/icmpv6.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 defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
  47 #include <net/xfrm.h>
  48 #endif
  49
  50 #include <asm/uaccess.h>
  51
  52 int ipv6_find_tlv(struct sk_buff *skb, int offset, int type)
  53 {
  54         const unsigned char *nh = skb_network_header(skb);
  55         int packet_len = skb->tail - skb->network_header;
  56         struct ipv6_opt_hdr *hdr;
  57         int len;
  58
  59         if (offset + 2 > packet_len)
  60                 goto bad;
  61         hdr = (struct ipv6_opt_hdr *)(nh + offset);
  62         len = ((hdr->hdrlen + 1) << 3);
  63
  64         if (offset + len > packet_len)
  65                 goto bad;
  66
  67         offset += 2;
  68         len -= 2;
  69
  70         while (len > 0) {
  71                 int opttype = nh[offset];
  72                 int optlen;
  73
  74                 if (opttype == type)
  75                         return offset;
  76
  77                 switch (opttype) {
  78                 case IPV6_TLV_PAD0:
  79                         optlen = 1;
  80                         break;
  81                 default:
  82                         optlen = nh[offset + 1] + 2;
  83                         if (optlen > len)
  84                                 goto bad;
  85                         break;
  86                 }
  87                 offset += optlen;
  88                 len -= optlen;
  89         }
  90         /* not_found */
  91  bad:
  92         return -1;
  93 }
  94 EXPORT_SYMBOL_GPL(ipv6_find_tlv);
  95
  96 /*
  97  *      Parsing tlv encoded headers.
  98  *
  99  *      Parsing function "func" returns 1, if parsing succeed
 100  *      and 0, if it failed.
 101  *      It MUST NOT touch skb->h.
 102  */
 103
 104 struct tlvtype_proc {
 105         int     type;
 106         int     (*func)(struct sk_buff *skb, int offset);
 107 };
 108
 109 /*********************
 110   Generic functions
 111  *********************/
 112
 113 /* An unknown option is detected, decide what to do */
 114
 115 static int ip6_tlvopt_unknown(struct sk_buff *skb, int optoff)
 116 {
 117         switch ((skb_network_header(skb)[optoff] & 0xC0) >> 6) {
 118         case 0: /* ignore */
 119                 return 1;
 120
 121         case 1: /* drop packet */
 122                 break;
 123
 124         case 3: /* Send ICMP if not a multicast address and drop packet */
 125                 /* Actually, it is redundant check. icmp_send
 126                    will recheck in any case.
 127                  */
 128                 if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr))
 129                         break;
 130         case 2: /* send ICMP PARM PROB regardless and drop packet */
 131                 icmpv6_param_prob(skb, ICMPV6_UNK_OPTION, optoff);
 132                 return 0;
 133         }
 134
 135         kfree_skb(skb);
 136         return 0;
 137 }
 138
 139 /* Parse tlv encoded option header (hop-by-hop or destination) */
 140
 141 static int ip6_parse_tlv(struct tlvtype_proc *procs, struct sk_buff *skb)
 142 {
 143         struct tlvtype_proc *curr;
 144         const unsigned char *nh = skb_network_header(skb);
 145         int off = skb_network_header_len(skb);
 146         int len = (skb_transport_header(skb)[1] + 1) << 3;
 147
 148         if (skb_transport_offset(skb) + len > skb_headlen(skb))
 149                 goto bad;
 150
 151         off += 2;
 152         len -= 2;
 153
 154         while (len > 0) {
 155                 int optlen = nh[off + 1] + 2;
 156
 157                 switch (nh[off]) {
 158                 case IPV6_TLV_PAD0:
 159                         optlen = 1;
 160                         break;
 161
 162                 case IPV6_TLV_PADN:
 163                         break;
 164
 165                 default: /* Other TLV code so scan list */
 166                         if (optlen > len)
 167                                 goto bad;
 168                         for (curr=procs; curr->type >= 0; curr++) {
 169                                 if (curr->type == nh[off]) {
 170                                         /* type specific length/alignment
 171                                            checks will be performed in the
 172                                            func(). */
 173                                         if (curr->func(skb, off) == 0)
 174                                                 return 0;
 175                                         break;
 176                                 }
 177                         }
 178                         if (curr->type < 0) {
 179                                 if (ip6_tlvopt_unknown(skb, off) == 0)
 180                                         return 0;
 181                         }
 182                         break;
 183                 }
 184                 off += optlen;
 185                 len -= optlen;
 186         }
 187         if (len == 0)
 188                 return 1;
 189 bad:
 190         kfree_skb(skb);
 191         return 0;
 192 }
 193
 194 /*****************************
 195   Destination options header.
 196  *****************************/
 197
 198 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 199 static int ipv6_dest_hao(struct sk_buff *skb, int optoff)
 200 {
 201         struct ipv6_destopt_hao *hao;
 202         struct inet6_skb_parm *opt = IP6CB(skb);
 203         struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 204         struct in6_addr tmp_addr;
 205         int ret;
 206
 207         if (opt->dsthao) {
 208                 LIMIT_NETDEBUG(KERN_DEBUG "hao duplicated\n");
 209                 goto discard;
 210         }
 211         opt->dsthao = opt->dst1;
 212         opt->dst1 = 0;
 213
 214         hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) + optoff);
 215
 216         if (hao->length != 16) {
 217                 LIMIT_NETDEBUG(
 218                         KERN_DEBUG "hao invalid option length = %d\n", hao->length);
 219                 goto discard;
 220         }
 221
 222         if (!(ipv6_addr_type(&hao->addr) & IPV6_ADDR_UNICAST)) {
 223                 LIMIT_NETDEBUG(
 224                         KERN_DEBUG "hao is not an unicast addr: " NIP6_FMT "\n", NIP6(hao->addr));
 225                 goto discard;
 226         }
 227
 228         ret = xfrm6_input_addr(skb, (xfrm_address_t *)&ipv6h->daddr,
 229                                (xfrm_address_t *)&hao->addr, IPPROTO_DSTOPTS);
 230         if (unlikely(ret < 0))
 231                 goto discard;
 232
 233         if (skb_cloned(skb)) {
 234                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 235                         goto discard;
 236
 237                 /* update all variable using below by copied skbuff */
 238                 hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) +
 239                                                   optoff);
 240                 ipv6h = ipv6_hdr(skb);
 241         }
 242
 243         if (skb->ip_summed == CHECKSUM_COMPLETE)
 244                 skb->ip_summed = CHECKSUM_NONE;
 245
 246         ipv6_addr_copy(&tmp_addr, &ipv6h->saddr);
 247         ipv6_addr_copy(&ipv6h->saddr, &hao->addr);
 248         ipv6_addr_copy(&hao->addr, &tmp_addr);
 249
 250         if (skb->tstamp.tv64 == 0)
 251                 __net_timestamp(skb);
 252
 253         return 1;
 254
 255  discard:
 256         kfree_skb(skb);
 257         return 0;
 258 }
 259 #endif
 260
 261 static struct tlvtype_proc tlvprocdestopt_lst[] = {
 262 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 263         {
 264                 .type   = IPV6_TLV_HAO,
 265                 .func   = ipv6_dest_hao,
 266         },
 267 #endif
 268         {-1,                    NULL}
 269 };
 270
 271 static int ipv6_destopt_rcv(struct sk_buff *skb)
 272 {
 273         struct inet6_skb_parm *opt = IP6CB(skb);
 274 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 275         __u16 dstbuf;
 276 #endif
 277         struct dst_entry *dst;
 278
 279         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 280             !pskb_may_pull(skb, (skb_transport_offset(skb) +
 281                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 282                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 283                                  IPSTATS_MIB_INHDRERRORS);
 284                 kfree_skb(skb);
 285                 return -1;
 286         }
 287
 288         opt->lastopt = opt->dst1 = skb_network_header_len(skb);
 289 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 290         dstbuf = opt->dst1;
 291 #endif
 292
 293         dst = dst_clone(skb->dst);
 294         if (ip6_parse_tlv(tlvprocdestopt_lst, skb)) {
 295                 dst_release(dst);
 296                 skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
 297                 opt = IP6CB(skb);
 298 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 299                 opt->nhoff = dstbuf;
 300 #else
 301                 opt->nhoff = opt->dst1;
 302 #endif
 303                 return 1;
 304         }
 305
 306         IP6_INC_STATS_BH(ip6_dst_idev(dst), IPSTATS_MIB_INHDRERRORS);
 307         dst_release(dst);
 308         return -1;
 309 }
 310
 311 /********************************
 312   Routing header.
 313  ********************************/
 314
 315 static int ipv6_rthdr_rcv(struct sk_buff *skb)
 316 {
 317         struct inet6_skb_parm *opt = IP6CB(skb);
 318         struct in6_addr *addr = NULL;
 319         struct in6_addr daddr;
 320         struct inet6_dev *idev;
 321         int n, i;
 322         struct ipv6_rt_hdr *hdr;
 323         struct rt0_hdr *rthdr;
 324         int accept_source_route = ipv6_devconf.accept_source_route;
 325
 326         idev = in6_dev_get(skb->dev);
 327         if (idev) {
 328                 if (accept_source_route > idev->cnf.accept_source_route)
 329                         accept_source_route = idev->cnf.accept_source_route;
 330                 in6_dev_put(idev);
 331         }
 332
 333         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 334             !pskb_may_pull(skb, (skb_transport_offset(skb) +
 335                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 336                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 337                                  IPSTATS_MIB_INHDRERRORS);
 338                 kfree_skb(skb);
 339                 return -1;
 340         }
 341
 342         hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 343
 344         if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ||
 345             skb->pkt_type != PACKET_HOST) {
 346                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 347                                  IPSTATS_MIB_INADDRERRORS);
 348                 kfree_skb(skb);
 349                 return -1;
 350         }
 351
 352 looped_back:
 353         if (hdr->segments_left == 0) {
 354                 switch (hdr->type) {
 355 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 356                 case IPV6_SRCRT_TYPE_2:
 357                         /* Silently discard type 2 header unless it was
 358                          * processed by own
 359                          */
 360                         if (!addr) {
 361                                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 362                                                  IPSTATS_MIB_INADDRERRORS);
 363                                 kfree_skb(skb);
 364                                 return -1;
 365                         }
 366                         break;
 367 #endif
 368                 default:
 369                         break;
 370                 }
 371
 372                 opt->lastopt = opt->srcrt = skb_network_header_len(skb);
 373                 skb->transport_header += (hdr->hdrlen + 1) << 3;
 374                 opt->dst0 = opt->dst1;
 375                 opt->dst1 = 0;
 376                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
 377                 return 1;
 378         }
 379
 380         switch (hdr->type) {
 381 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 382         case IPV6_SRCRT_TYPE_2:
 383                 if (accept_source_route < 0)
 384                         goto unknown_rh;
 385                 /* Silently discard invalid RTH type 2 */
 386                 if (hdr->hdrlen != 2 || hdr->segments_left != 1) {
 387                         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 388                                          IPSTATS_MIB_INHDRERRORS);
 389                         kfree_skb(skb);
 390                         return -1;
 391                 }
 392                 break;
 393 #endif
 394         default:
 395                 goto unknown_rh;
 396         }
 397
 398         /*
 399          *      This is the routing header forwarding algorithm from
 400          *      RFC 2460, page 16.
 401          */
 402
 403         n = hdr->hdrlen >> 1;
 404
 405         if (hdr->segments_left > n) {
 406                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 407                                  IPSTATS_MIB_INHDRERRORS);
 408                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 409                                   ((&hdr->segments_left) -
 410                                    skb_network_header(skb)));
 411                 return -1;
 412         }
 413
 414         /* We are about to mangle packet header. Be careful!
 415            Do not damage packets queued somewhere.
 416          */
 417         if (skb_cloned(skb)) {
 418                 /* the copy is a forwarded packet */
 419                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
 420                         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 421                                          IPSTATS_MIB_OUTDISCARDS);
 422                         kfree_skb(skb);
 423                         return -1;
 424                 }
 425                 hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 426         }
 427
 428         if (skb->ip_summed == CHECKSUM_COMPLETE)
 429                 skb->ip_summed = CHECKSUM_NONE;
 430
 431         i = n - --hdr->segments_left;
 432
 433         rthdr = (struct rt0_hdr *) hdr;
 434         addr = rthdr->addr;
 435         addr += i - 1;
 436
 437         switch (hdr->type) {
 438 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 439         case IPV6_SRCRT_TYPE_2:
 440                 if (xfrm6_input_addr(skb, (xfrm_address_t *)addr,
 441                                      (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 442                                      IPPROTO_ROUTING) < 0) {
 443                         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 444                                          IPSTATS_MIB_INADDRERRORS);
 445                         kfree_skb(skb);
 446                         return -1;
 447                 }
 448                 if (!ipv6_chk_home_addr(&init_net, addr)) {
 449                         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 450                                          IPSTATS_MIB_INADDRERRORS);
 451                         kfree_skb(skb);
 452                         return -1;
 453                 }
 454                 break;
 455 #endif
 456         default:
 457                 break;
 458         }
 459
 460         if (ipv6_addr_is_multicast(addr)) {
 461                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 462                                  IPSTATS_MIB_INADDRERRORS);
 463                 kfree_skb(skb);
 464                 return -1;
 465         }
 466
 467         ipv6_addr_copy(&daddr, addr);
 468         ipv6_addr_copy(addr, &ipv6_hdr(skb)->daddr);
 469         ipv6_addr_copy(&ipv6_hdr(skb)->daddr, &daddr);
 470
 471         dst_release(xchg(&skb->dst, NULL));
 472         ip6_route_input(skb);
 473         if (skb->dst->error) {
 474                 skb_push(skb, skb->data - skb_network_header(skb));
 475                 dst_input(skb);
 476                 return -1;
 477         }
 478
 479         if (skb->dst->dev->flags&IFF_LOOPBACK) {
 480                 if (ipv6_hdr(skb)->hop_limit <= 1) {
 481                         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
 482                                          IPSTATS_MIB_INHDRERRORS);
 483                         icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
 484                                     0, skb->dev);
 485                         kfree_skb(skb);
 486                         return -1;
 487                 }
 488                 ipv6_hdr(skb)->hop_limit--;
 489                 goto looped_back;
 490         }
 491
 492         skb_push(skb, skb->data - skb_network_header(skb));
 493         dst_input(skb);
 494         return -1;
 495
 496 unknown_rh:
 497         IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_INHDRERRORS);
 498         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 499                           (&hdr->type) - skb_network_header(skb));
 500         return -1;
 501 }
 502
 503 static struct inet6_protocol rthdr_protocol = {
 504         .handler        =       ipv6_rthdr_rcv,
 505         .flags          =       INET6_PROTO_NOPOLICY | INET6_PROTO_GSO_EXTHDR,
 506 };
 507
 508 static struct inet6_protocol destopt_protocol = {
 509         .handler        =       ipv6_destopt_rcv,
 510         .flags          =       INET6_PROTO_NOPOLICY | INET6_PROTO_GSO_EXTHDR,
 511 };
 512
 513 static struct inet6_protocol nodata_protocol = {
 514         .handler        =       dst_discard,
 515         .flags          =       INET6_PROTO_NOPOLICY,
 516 };
 517
 518 int __init ipv6_exthdrs_init(void)
 519 {
 520         int ret;
 521
 522         ret = inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 523         if (ret)
 524                 goto out;
 525
 526         ret = inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 527         if (ret)
 528                 goto out_rthdr;
 529
 530         ret = inet6_add_protocol(&nodata_protocol, IPPROTO_NONE);
 531         if (ret)
 532                 goto out_destopt;
 533
 534 out:
 535         return ret;
 536 out_rthdr:
 537         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 538 out_destopt:
 539         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 540         goto out;
 541 };
 542
 543 void ipv6_exthdrs_exit(void)
 544 {
 545         inet6_del_protocol(&nodata_protocol, IPPROTO_NONE);
 546         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 547         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 548 }
 549
 550 /**********************************
 551   Hop-by-hop options.
 552  **********************************/
 553
 554 /*
 555  * Note: we cannot rely on skb->dst before we assign it in ip6_route_input().
 556  */
 557 static inline struct inet6_dev *ipv6_skb_idev(struct sk_buff *skb)
 558 {
 559         return skb->dst ? ip6_dst_idev(skb->dst) : __in6_dev_get(skb->dev);
 560 }
 561
 562 /* Router Alert as of RFC 2711 */
 563
 564 static int ipv6_hop_ra(struct sk_buff *skb, int optoff)
 565 {
 566         const unsigned char *nh = skb_network_header(skb);
 567
 568         if (nh[optoff + 1] == 2) {
 569                 IP6CB(skb)->ra = optoff;
 570                 return 1;
 571         }
 572         LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_ra: wrong RA length %d\n",
 573                        nh[optoff + 1]);
 574         kfree_skb(skb);
 575         return 0;
 576 }
 577
 578 /* Jumbo payload */
 579
 580 static int ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
 581 {
 582         const unsigned char *nh = skb_network_header(skb);
 583         u32 pkt_len;
 584
 585         if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
 586                 LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
 587                                nh[optoff+1]);
 588                 IP6_INC_STATS_BH(ipv6_skb_idev(skb),
 589                                  IPSTATS_MIB_INHDRERRORS);
 590                 goto drop;
 591         }
 592
 593         pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
 594         if (pkt_len <= IPV6_MAXPLEN) {
 595                 IP6_INC_STATS_BH(ipv6_skb_idev(skb), IPSTATS_MIB_INHDRERRORS);
 596                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2);
 597                 return 0;
 598         }
 599         if (ipv6_hdr(skb)->payload_len) {
 600                 IP6_INC_STATS_BH(ipv6_skb_idev(skb), IPSTATS_MIB_INHDRERRORS);
 601                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff);
 602                 return 0;
 603         }
 604
 605         if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
 606                 IP6_INC_STATS_BH(ipv6_skb_idev(skb), IPSTATS_MIB_INTRUNCATEDPKTS);
 607                 goto drop;
 608         }
 609
 610         if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 611                 goto drop;
 612
 613         return 1;
 614
 615 drop:
 616         kfree_skb(skb);
 617         return 0;
 618 }
 619
 620 static struct tlvtype_proc tlvprochopopt_lst[] = {
 621         {
 622                 .type   = IPV6_TLV_ROUTERALERT,
 623                 .func   = ipv6_hop_ra,
 624         },
 625         {
 626                 .type   = IPV6_TLV_JUMBO,
 627                 .func   = ipv6_hop_jumbo,
 628         },
 629         { -1, }
 630 };
 631
 632 int ipv6_parse_hopopts(struct sk_buff *skb)
 633 {
 634         struct inet6_skb_parm *opt = IP6CB(skb);
 635
 636         /*
 637          * skb_network_header(skb) is equal to skb->data, and
 638          * skb_network_header_len(skb) is always equal to
 639          * sizeof(struct ipv6hdr) by definition of
 640          * hop-by-hop options.
 641          */
 642         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
 643             !pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
 644                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 645                 kfree_skb(skb);
 646                 return -1;
 647         }
 648
 649         opt->hop = sizeof(struct ipv6hdr);
 650         if (ip6_parse_tlv(tlvprochopopt_lst, skb)) {
 651                 skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
 652                 opt = IP6CB(skb);
 653                 opt->nhoff = sizeof(struct ipv6hdr);
 654                 return 1;
 655         }
 656         return -1;
 657 }
 658
 659 /*
 660  *      Creating outbound headers.
 661  *
 662  *      "build" functions work when skb is filled from head to tail (datagram)
 663  *      "push"  functions work when headers are added from tail to head (tcp)
 664  *
 665  *      In both cases we assume, that caller reserved enough room
 666  *      for headers.
 667  */
 668
 669 static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
 670                             struct ipv6_rt_hdr *opt,
 671                             struct in6_addr **addr_p)
 672 {
 673         struct rt0_hdr *phdr, *ihdr;
 674         int hops;
 675
 676         ihdr = (struct rt0_hdr *) opt;
 677
 678         phdr = (struct rt0_hdr *) skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
 679         memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
 680
 681         hops = ihdr->rt_hdr.hdrlen >> 1;
 682
 683         if (hops > 1)
 684                 memcpy(phdr->addr, ihdr->addr + 1,
 685                        (hops - 1) * sizeof(struct in6_addr));
 686
 687         ipv6_addr_copy(phdr->addr + (hops - 1), *addr_p);
 688         *addr_p = ihdr->addr;
 689
 690         phdr->rt_hdr.nexthdr = *proto;
 691         *proto = NEXTHDR_ROUTING;
 692 }
 693
 694 static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
 695 {
 696         struct ipv6_opt_hdr *h = (struct ipv6_opt_hdr *)skb_push(skb, ipv6_optlen(opt));
 697
 698         memcpy(h, opt, ipv6_optlen(opt));
 699         h->nexthdr = *proto;
 700         *proto = type;
 701 }
 702
 703 void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
 704                           u8 *proto,
 705                           struct in6_addr **daddr)
 706 {
 707         if (opt->srcrt) {
 708                 ipv6_push_rthdr(skb, proto, opt->srcrt, daddr);
 709                 /*
 710                  * IPV6_RTHDRDSTOPTS is ignored
 711                  * unless IPV6_RTHDR is set (RFC3542).
 712                  */
 713                 if (opt->dst0opt)
 714                         ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
 715         }
 716         if (opt->hopopt)
 717                 ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
 718 }
 719
 720 EXPORT_SYMBOL(ipv6_push_nfrag_opts);
 721
 722 void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
 723 {
 724         if (opt->dst1opt)
 725                 ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
 726 }
 727
 728 struct ipv6_txoptions *
 729 ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
 730 {
 731         struct ipv6_txoptions *opt2;
 732
 733         opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
 734         if (opt2) {
 735                 long dif = (char*)opt2 - (char*)opt;
 736                 memcpy(opt2, opt, opt->tot_len);
 737                 if (opt2->hopopt)
 738                         *((char**)&opt2->hopopt) += dif;
 739                 if (opt2->dst0opt)
 740                         *((char**)&opt2->dst0opt) += dif;
 741                 if (opt2->dst1opt)
 742                         *((char**)&opt2->dst1opt) += dif;
 743                 if (opt2->srcrt)
 744                         *((char**)&opt2->srcrt) += dif;
 745         }
 746         return opt2;
 747 }
 748
 749 EXPORT_SYMBOL_GPL(ipv6_dup_options);
 750
 751 static int ipv6_renew_option(void *ohdr,
 752                              struct ipv6_opt_hdr __user *newopt, int newoptlen,
 753                              int inherit,
 754                              struct ipv6_opt_hdr **hdr,
 755                              char **p)
 756 {
 757         if (inherit) {
 758                 if (ohdr) {
 759                         memcpy(*p, ohdr, ipv6_optlen((struct ipv6_opt_hdr *)ohdr));
 760                         *hdr = (struct ipv6_opt_hdr *)*p;
 761                         *p += CMSG_ALIGN(ipv6_optlen(*(struct ipv6_opt_hdr **)hdr));
 762                 }
 763         } else {
 764                 if (newopt) {
 765                         if (copy_from_user(*p, newopt, newoptlen))
 766                                 return -EFAULT;
 767                         *hdr = (struct ipv6_opt_hdr *)*p;
 768                         if (ipv6_optlen(*(struct ipv6_opt_hdr **)hdr) > newoptlen)
 769                                 return -EINVAL;
 770                         *p += CMSG_ALIGN(newoptlen);
 771                 }
 772         }
 773         return 0;
 774 }
 775
 776 struct ipv6_txoptions *
 777 ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
 778                    int newtype,
 779                    struct ipv6_opt_hdr __user *newopt, int newoptlen)
 780 {
 781         int tot_len = 0;
 782         char *p;
 783         struct ipv6_txoptions *opt2;
 784         int err;
 785
 786         if (opt) {
 787                 if (newtype != IPV6_HOPOPTS && opt->hopopt)
 788                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
 789                 if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
 790                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
 791                 if (newtype != IPV6_RTHDR && opt->srcrt)
 792                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
 793                 if (newtype != IPV6_DSTOPTS && opt->dst1opt)
 794                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
 795         }
 796
 797         if (newopt && newoptlen)
 798                 tot_len += CMSG_ALIGN(newoptlen);
 799
 800         if (!tot_len)
 801                 return NULL;
 802
 803         tot_len += sizeof(*opt2);
 804         opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
 805         if (!opt2)
 806                 return ERR_PTR(-ENOBUFS);
 807
 808         memset(opt2, 0, tot_len);
 809
 810         opt2->tot_len = tot_len;
 811         p = (char *)(opt2 + 1);
 812
 813         err = ipv6_renew_option(opt ? opt->hopopt : NULL, newopt, newoptlen,
 814                                 newtype != IPV6_HOPOPTS,
 815                                 &opt2->hopopt, &p);
 816         if (err)
 817                 goto out;
 818
 819         err = ipv6_renew_option(opt ? opt->dst0opt : NULL, newopt, newoptlen,
 820                                 newtype != IPV6_RTHDRDSTOPTS,
 821                                 &opt2->dst0opt, &p);
 822         if (err)
 823                 goto out;
 824
 825         err = ipv6_renew_option(opt ? opt->srcrt : NULL, newopt, newoptlen,
 826                                 newtype != IPV6_RTHDR,
 827                                 (struct ipv6_opt_hdr **)&opt2->srcrt, &p);
 828         if (err)
 829                 goto out;
 830
 831         err = ipv6_renew_option(opt ? opt->dst1opt : NULL, newopt, newoptlen,
 832                                 newtype != IPV6_DSTOPTS,
 833                                 &opt2->dst1opt, &p);
 834         if (err)
 835                 goto out;
 836
 837         opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
 838                           (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
 839                           (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
 840         opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
 841
 842         return opt2;
 843 out:
 844         sock_kfree_s(sk, opt2, opt2->tot_len);
 845         return ERR_PTR(err);
 846 }
 847
 848 struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space,
 849                                           struct ipv6_txoptions *opt)
 850 {
 851         /*
 852          * ignore the dest before srcrt unless srcrt is being included.
 853          * --yoshfuji
 854          */
 855         if (opt && opt->dst0opt && !opt->srcrt) {
 856                 if (opt_space != opt) {
 857                         memcpy(opt_space, opt, sizeof(*opt_space));
 858                         opt = opt_space;
 859                 }
 860                 opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
 861                 opt->dst0opt = NULL;
 862         }
 863
 864         return opt;
 865 }
 866