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 #include <net/calipso.h>
  47 #if IS_ENABLED(CONFIG_IPV6_MIP6)
  48 #include <net/xfrm.h>
  49 #endif
  50
  51 #include <linux/uaccess.h>
  52
  53 /*
  54  *      Parsing tlv encoded headers.
  55  *
  56  *      Parsing function "func" returns true, if parsing succeed
  57  *      and false, if it failed.
  58  *      It MUST NOT touch skb->h.
  59  */
  60
  61 struct tlvtype_proc {
  62         int     type;
  63         bool    (*func)(struct sk_buff *skb, int offset);
  64 };
  65
  66 /*********************
  67   Generic functions
  68  *********************/
  69
  70 /* An unknown option is detected, decide what to do */
  71
  72 static bool ip6_tlvopt_unknown(struct sk_buff *skb, int optoff)
  73 {
  74         switch ((skb_network_header(skb)[optoff] & 0xC0) >> 6) {
  75         case 0: /* ignore */
  76                 return true;
  77
  78         case 1: /* drop packet */
  79                 break;
  80
  81         case 3: /* Send ICMP if not a multicast address and drop packet */
  82                 /* Actually, it is redundant check. icmp_send
  83                    will recheck in any case.
  84                  */
  85                 if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr))
  86                         break;
  87         case 2: /* send ICMP PARM PROB regardless and drop packet */
  88                 icmpv6_param_prob(skb, ICMPV6_UNK_OPTION, optoff);
  89                 return false;
  90         }
  91
  92         kfree_skb(skb);
  93         return false;
  94 }
  95
  96 /* Parse tlv encoded option header (hop-by-hop or destination) */
  97
  98 static bool ip6_parse_tlv(const struct tlvtype_proc *procs, struct sk_buff *skb)
  99 {
 100         const struct tlvtype_proc *curr;
 101         const unsigned char *nh = skb_network_header(skb);
 102         int off = skb_network_header_len(skb);
 103         int len = (skb_transport_header(skb)[1] + 1) << 3;
 104         int padlen = 0;
 105
 106         if (skb_transport_offset(skb) + len > skb_headlen(skb))
 107                 goto bad;
 108
 109         off += 2;
 110         len -= 2;
 111
 112         while (len > 0) {
 113                 int optlen = nh[off + 1] + 2;
 114                 int i;
 115
 116                 switch (nh[off]) {
 117                 case IPV6_TLV_PAD1:
 118                         optlen = 1;
 119                         padlen++;
 120                         if (padlen > 7)
 121                                 goto bad;
 122                         break;
 123
 124                 case IPV6_TLV_PADN:
 125                         /* RFC 2460 states that the purpose of PadN is
 126                          * to align the containing header to multiples
 127                          * of 8. 7 is therefore the highest valid value.
 128                          * See also RFC 4942, Section 2.1.9.5.
 129                          */
 130                         padlen += optlen;
 131                         if (padlen > 7)
 132                                 goto bad;
 133                         /* RFC 4942 recommends receiving hosts to
 134                          * actively check PadN payload to contain
 135                          * only zeroes.
 136                          */
 137                         for (i = 2; i < optlen; i++) {
 138                                 if (nh[off + i] != 0)
 139                                         goto bad;
 140                         }
 141                         break;
 142
 143                 default: /* Other TLV code so scan list */
 144                         if (optlen > len)
 145                                 goto bad;
 146                         for (curr = procs; curr->type >= 0; curr++) {
 147                                 if (curr->type == nh[off]) {
 148                                         /* type specific length/alignment
 149                                            checks will be performed in the
 150                                            func(). */
 151                                         if (curr->func(skb, off) == false)
 152                                                 return false;
 153                                         break;
 154                                 }
 155                         }
 156                         if (curr->type < 0) {
 157                                 if (ip6_tlvopt_unknown(skb, off) == 0)
 158                                         return false;
 159                         }
 160                         padlen = 0;
 161                         break;
 162                 }
 163                 off += optlen;
 164                 len -= optlen;
 165         }
 166
 167         if (len == 0)
 168                 return true;
 169 bad:
 170         kfree_skb(skb);
 171         return false;
 172 }
 173
 174 /*****************************
 175   Destination options header.
 176  *****************************/
 177
 178 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 179 static bool ipv6_dest_hao(struct sk_buff *skb, int optoff)
 180 {
 181         struct ipv6_destopt_hao *hao;
 182         struct inet6_skb_parm *opt = IP6CB(skb);
 183         struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 184         struct in6_addr tmp_addr;
 185         int ret;
 186
 187         if (opt->dsthao) {
 188                 net_dbg_ratelimited("hao duplicated\n");
 189                 goto discard;
 190         }
 191         opt->dsthao = opt->dst1;
 192         opt->dst1 = 0;
 193
 194         hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) + optoff);
 195
 196         if (hao->length != 16) {
 197                 net_dbg_ratelimited("hao invalid option length = %d\n",
 198                                     hao->length);
 199                 goto discard;
 200         }
 201
 202         if (!(ipv6_addr_type(&hao->addr) & IPV6_ADDR_UNICAST)) {
 203                 net_dbg_ratelimited("hao is not an unicast addr: %pI6\n",
 204                                     &hao->addr);
 205                 goto discard;
 206         }
 207
 208         ret = xfrm6_input_addr(skb, (xfrm_address_t *)&ipv6h->daddr,
 209                                (xfrm_address_t *)&hao->addr, IPPROTO_DSTOPTS);
 210         if (unlikely(ret < 0))
 211                 goto discard;
 212
 213         if (skb_cloned(skb)) {
 214                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 215                         goto discard;
 216
 217                 /* update all variable using below by copied skbuff */
 218                 hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) +
 219                                                   optoff);
 220                 ipv6h = ipv6_hdr(skb);
 221         }
 222
 223         if (skb->ip_summed == CHECKSUM_COMPLETE)
 224                 skb->ip_summed = CHECKSUM_NONE;
 225
 226         tmp_addr = ipv6h->saddr;
 227         ipv6h->saddr = hao->addr;
 228         hao->addr = tmp_addr;
 229
 230         if (skb->tstamp.tv64 == 0)
 231                 __net_timestamp(skb);
 232
 233         return true;
 234
 235  discard:
 236         kfree_skb(skb);
 237         return false;
 238 }
 239 #endif
 240
 241 static const struct tlvtype_proc tlvprocdestopt_lst[] = {
 242 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 243         {
 244                 .type   = IPV6_TLV_HAO,
 245                 .func   = ipv6_dest_hao,
 246         },
 247 #endif
 248         {-1,                    NULL}
 249 };
 250
 251 static int ipv6_destopt_rcv(struct sk_buff *skb)
 252 {
 253         struct inet6_skb_parm *opt = IP6CB(skb);
 254 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 255         __u16 dstbuf;
 256 #endif
 257         struct dst_entry *dst = skb_dst(skb);
 258
 259         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 260             !pskb_may_pull(skb, (skb_transport_offset(skb) +
 261                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 262                 __IP6_INC_STATS(dev_net(dst->dev), ip6_dst_idev(dst),
 263                                 IPSTATS_MIB_INHDRERRORS);
 264                 kfree_skb(skb);
 265                 return -1;
 266         }
 267
 268         opt->lastopt = opt->dst1 = skb_network_header_len(skb);
 269 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 270         dstbuf = opt->dst1;
 271 #endif
 272
 273         if (ip6_parse_tlv(tlvprocdestopt_lst, skb)) {
 274                 skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
 275                 opt = IP6CB(skb);
 276 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 277                 opt->nhoff = dstbuf;
 278 #else
 279                 opt->nhoff = opt->dst1;
 280 #endif
 281                 return 1;
 282         }
 283
 284         __IP6_INC_STATS(dev_net(dst->dev),
 285                         ip6_dst_idev(dst), IPSTATS_MIB_INHDRERRORS);
 286         return -1;
 287 }
 288
 289 /********************************
 290   Routing header.
 291  ********************************/
 292
 293 /* called with rcu_read_lock() */
 294 static int ipv6_rthdr_rcv(struct sk_buff *skb)
 295 {
 296         struct inet6_skb_parm *opt = IP6CB(skb);
 297         struct in6_addr *addr = NULL;
 298         struct in6_addr daddr;
 299         struct inet6_dev *idev;
 300         int n, i;
 301         struct ipv6_rt_hdr *hdr;
 302         struct rt0_hdr *rthdr;
 303         struct net *net = dev_net(skb->dev);
 304         int accept_source_route = net->ipv6.devconf_all->accept_source_route;
 305
 306         idev = __in6_dev_get(skb->dev);
 307         if (idev && accept_source_route > idev->cnf.accept_source_route)
 308                 accept_source_route = idev->cnf.accept_source_route;
 309
 310         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 311             !pskb_may_pull(skb, (skb_transport_offset(skb) +
 312                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 313                 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 314                                 IPSTATS_MIB_INHDRERRORS);
 315                 kfree_skb(skb);
 316                 return -1;
 317         }
 318
 319         hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 320
 321         if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ||
 322             skb->pkt_type != PACKET_HOST) {
 323                 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 324                                 IPSTATS_MIB_INADDRERRORS);
 325                 kfree_skb(skb);
 326                 return -1;
 327         }
 328
 329 looped_back:
 330         if (hdr->segments_left == 0) {
 331                 switch (hdr->type) {
 332 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 333                 case IPV6_SRCRT_TYPE_2:
 334                         /* Silently discard type 2 header unless it was
 335                          * processed by own
 336                          */
 337                         if (!addr) {
 338                                 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 339                                                 IPSTATS_MIB_INADDRERRORS);
 340                                 kfree_skb(skb);
 341                                 return -1;
 342                         }
 343                         break;
 344 #endif
 345                 default:
 346                         break;
 347                 }
 348
 349                 opt->lastopt = opt->srcrt = skb_network_header_len(skb);
 350                 skb->transport_header += (hdr->hdrlen + 1) << 3;
 351                 opt->dst0 = opt->dst1;
 352                 opt->dst1 = 0;
 353                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
 354                 return 1;
 355         }
 356
 357         switch (hdr->type) {
 358 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 359         case IPV6_SRCRT_TYPE_2:
 360                 if (accept_source_route < 0)
 361                         goto unknown_rh;
 362                 /* Silently discard invalid RTH type 2 */
 363                 if (hdr->hdrlen != 2 || hdr->segments_left != 1) {
 364                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 365                                         IPSTATS_MIB_INHDRERRORS);
 366                         kfree_skb(skb);
 367                         return -1;
 368                 }
 369                 break;
 370 #endif
 371         default:
 372                 goto unknown_rh;
 373         }
 374
 375         /*
 376          *      This is the routing header forwarding algorithm from
 377          *      RFC 2460, page 16.
 378          */
 379
 380         n = hdr->hdrlen >> 1;
 381
 382         if (hdr->segments_left > n) {
 383                 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 384                                 IPSTATS_MIB_INHDRERRORS);
 385                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 386                                   ((&hdr->segments_left) -
 387                                    skb_network_header(skb)));
 388                 return -1;
 389         }
 390
 391         /* We are about to mangle packet header. Be careful!
 392            Do not damage packets queued somewhere.
 393          */
 394         if (skb_cloned(skb)) {
 395                 /* the copy is a forwarded packet */
 396                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
 397                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 398                                         IPSTATS_MIB_OUTDISCARDS);
 399                         kfree_skb(skb);
 400                         return -1;
 401                 }
 402                 hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 403         }
 404
 405         if (skb->ip_summed == CHECKSUM_COMPLETE)
 406                 skb->ip_summed = CHECKSUM_NONE;
 407
 408         i = n - --hdr->segments_left;
 409
 410         rthdr = (struct rt0_hdr *) hdr;
 411         addr = rthdr->addr;
 412         addr += i - 1;
 413
 414         switch (hdr->type) {
 415 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 416         case IPV6_SRCRT_TYPE_2:
 417                 if (xfrm6_input_addr(skb, (xfrm_address_t *)addr,
 418                                      (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 419                                      IPPROTO_ROUTING) < 0) {
 420                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 421                                         IPSTATS_MIB_INADDRERRORS);
 422                         kfree_skb(skb);
 423                         return -1;
 424                 }
 425                 if (!ipv6_chk_home_addr(dev_net(skb_dst(skb)->dev), addr)) {
 426                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 427                                         IPSTATS_MIB_INADDRERRORS);
 428                         kfree_skb(skb);
 429                         return -1;
 430                 }
 431                 break;
 432 #endif
 433         default:
 434                 break;
 435         }
 436
 437         if (ipv6_addr_is_multicast(addr)) {
 438                 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 439                                 IPSTATS_MIB_INADDRERRORS);
 440                 kfree_skb(skb);
 441                 return -1;
 442         }
 443
 444         daddr = *addr;
 445         *addr = ipv6_hdr(skb)->daddr;
 446         ipv6_hdr(skb)->daddr = daddr;
 447
 448         skb_dst_drop(skb);
 449         ip6_route_input(skb);
 450         if (skb_dst(skb)->error) {
 451                 skb_push(skb, skb->data - skb_network_header(skb));
 452                 dst_input(skb);
 453                 return -1;
 454         }
 455
 456         if (skb_dst(skb)->dev->flags&IFF_LOOPBACK) {
 457                 if (ipv6_hdr(skb)->hop_limit <= 1) {
 458                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 459                                         IPSTATS_MIB_INHDRERRORS);
 460                         icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
 461                                     0);
 462                         kfree_skb(skb);
 463                         return -1;
 464                 }
 465                 ipv6_hdr(skb)->hop_limit--;
 466                 goto looped_back;
 467         }
 468
 469         skb_push(skb, skb->data - skb_network_header(skb));
 470         dst_input(skb);
 471         return -1;
 472
 473 unknown_rh:
 474         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS);
 475         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 476                           (&hdr->type) - skb_network_header(skb));
 477         return -1;
 478 }
 479
 480 static const struct inet6_protocol rthdr_protocol = {
 481         .handler        =       ipv6_rthdr_rcv,
 482         .flags          =       INET6_PROTO_NOPOLICY,
 483 };
 484
 485 static const struct inet6_protocol destopt_protocol = {
 486         .handler        =       ipv6_destopt_rcv,
 487         .flags          =       INET6_PROTO_NOPOLICY,
 488 };
 489
 490 static const struct inet6_protocol nodata_protocol = {
 491         .handler        =       dst_discard,
 492         .flags          =       INET6_PROTO_NOPOLICY,
 493 };
 494
 495 int __init ipv6_exthdrs_init(void)
 496 {
 497         int ret;
 498
 499         ret = inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 500         if (ret)
 501                 goto out;
 502
 503         ret = inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 504         if (ret)
 505                 goto out_rthdr;
 506
 507         ret = inet6_add_protocol(&nodata_protocol, IPPROTO_NONE);
 508         if (ret)
 509                 goto out_destopt;
 510
 511 out:
 512         return ret;
 513 out_destopt:
 514         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 515 out_rthdr:
 516         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 517         goto out;
 518 };
 519
 520 void ipv6_exthdrs_exit(void)
 521 {
 522         inet6_del_protocol(&nodata_protocol, IPPROTO_NONE);
 523         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 524         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 525 }
 526
 527 /**********************************
 528   Hop-by-hop options.
 529  **********************************/
 530
 531 /*
 532  * Note: we cannot rely on skb_dst(skb) before we assign it in ip6_route_input().
 533  */
 534 static inline struct inet6_dev *ipv6_skb_idev(struct sk_buff *skb)
 535 {
 536         return skb_dst(skb) ? ip6_dst_idev(skb_dst(skb)) : __in6_dev_get(skb->dev);
 537 }
 538
 539 static inline struct net *ipv6_skb_net(struct sk_buff *skb)
 540 {
 541         return skb_dst(skb) ? dev_net(skb_dst(skb)->dev) : dev_net(skb->dev);
 542 }
 543
 544 /* Router Alert as of RFC 2711 */
 545
 546 static bool ipv6_hop_ra(struct sk_buff *skb, int optoff)
 547 {
 548         const unsigned char *nh = skb_network_header(skb);
 549
 550         if (nh[optoff + 1] == 2) {
 551                 IP6CB(skb)->flags |= IP6SKB_ROUTERALERT;
 552                 memcpy(&IP6CB(skb)->ra, nh + optoff + 2, sizeof(IP6CB(skb)->ra));
 553                 return true;
 554         }
 555         net_dbg_ratelimited("ipv6_hop_ra: wrong RA length %d\n",
 556                             nh[optoff + 1]);
 557         kfree_skb(skb);
 558         return false;
 559 }
 560
 561 /* Jumbo payload */
 562
 563 static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
 564 {
 565         const unsigned char *nh = skb_network_header(skb);
 566         struct net *net = ipv6_skb_net(skb);
 567         u32 pkt_len;
 568
 569         if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
 570                 net_dbg_ratelimited("ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
 571                                     nh[optoff+1]);
 572                 __IP6_INC_STATS(net, ipv6_skb_idev(skb),
 573                                 IPSTATS_MIB_INHDRERRORS);
 574                 goto drop;
 575         }
 576
 577         pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
 578         if (pkt_len <= IPV6_MAXPLEN) {
 579                 __IP6_INC_STATS(net, ipv6_skb_idev(skb),
 580                                 IPSTATS_MIB_INHDRERRORS);
 581                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2);
 582                 return false;
 583         }
 584         if (ipv6_hdr(skb)->payload_len) {
 585                 __IP6_INC_STATS(net, ipv6_skb_idev(skb),
 586                                 IPSTATS_MIB_INHDRERRORS);
 587                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff);
 588                 return false;
 589         }
 590
 591         if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
 592                 __IP6_INC_STATS(net, ipv6_skb_idev(skb),
 593                                 IPSTATS_MIB_INTRUNCATEDPKTS);
 594                 goto drop;
 595         }
 596
 597         if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 598                 goto drop;
 599
 600         return true;
 601
 602 drop:
 603         kfree_skb(skb);
 604         return false;
 605 }
 606
 607 /* CALIPSO RFC 5570 */
 608
 609 static bool ipv6_hop_calipso(struct sk_buff *skb, int optoff)
 610 {
 611         const unsigned char *nh = skb_network_header(skb);
 612
 613         if (nh[optoff + 1] < 8)
 614                 goto drop;
 615
 616         if (nh[optoff + 6] * 4 + 8 > nh[optoff + 1])
 617                 goto drop;
 618
 619         if (!calipso_validate(skb, nh + optoff))
 620                 goto drop;
 621
 622         return true;
 623
 624 drop:
 625         kfree_skb(skb);
 626         return false;
 627 }
 628
 629 static const struct tlvtype_proc tlvprochopopt_lst[] = {
 630         {
 631                 .type   = IPV6_TLV_ROUTERALERT,
 632                 .func   = ipv6_hop_ra,
 633         },
 634         {
 635                 .type   = IPV6_TLV_JUMBO,
 636                 .func   = ipv6_hop_jumbo,
 637         },
 638         {
 639                 .type   = IPV6_TLV_CALIPSO,
 640                 .func   = ipv6_hop_calipso,
 641         },
 642         { -1, }
 643 };
 644
 645 int ipv6_parse_hopopts(struct sk_buff *skb)
 646 {
 647         struct inet6_skb_parm *opt = IP6CB(skb);
 648
 649         /*
 650          * skb_network_header(skb) is equal to skb->data, and
 651          * skb_network_header_len(skb) is always equal to
 652          * sizeof(struct ipv6hdr) by definition of
 653          * hop-by-hop options.
 654          */
 655         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
 656             !pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
 657                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 658                 kfree_skb(skb);
 659                 return -1;
 660         }
 661
 662         opt->flags |= IP6SKB_HOPBYHOP;
 663         if (ip6_parse_tlv(tlvprochopopt_lst, skb)) {
 664                 skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
 665                 opt = IP6CB(skb);
 666                 opt->nhoff = sizeof(struct ipv6hdr);
 667                 return 1;
 668         }
 669         return -1;
 670 }
 671
 672 /*
 673  *      Creating outbound headers.
 674  *
 675  *      "build" functions work when skb is filled from head to tail (datagram)
 676  *      "push"  functions work when headers are added from tail to head (tcp)
 677  *
 678  *      In both cases we assume, that caller reserved enough room
 679  *      for headers.
 680  */
 681
 682 static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
 683                             struct ipv6_rt_hdr *opt,
 684                             struct in6_addr **addr_p)
 685 {
 686         struct rt0_hdr *phdr, *ihdr;
 687         int hops;
 688
 689         ihdr = (struct rt0_hdr *) opt;
 690
 691         phdr = (struct rt0_hdr *) skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
 692         memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
 693
 694         hops = ihdr->rt_hdr.hdrlen >> 1;
 695
 696         if (hops > 1)
 697                 memcpy(phdr->addr, ihdr->addr + 1,
 698                        (hops - 1) * sizeof(struct in6_addr));
 699
 700         phdr->addr[hops - 1] = **addr_p;
 701         *addr_p = ihdr->addr;
 702
 703         phdr->rt_hdr.nexthdr = *proto;
 704         *proto = NEXTHDR_ROUTING;
 705 }
 706
 707 static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
 708 {
 709         struct ipv6_opt_hdr *h = (struct ipv6_opt_hdr *)skb_push(skb, ipv6_optlen(opt));
 710
 711         memcpy(h, opt, ipv6_optlen(opt));
 712         h->nexthdr = *proto;
 713         *proto = type;
 714 }
 715
 716 void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
 717                           u8 *proto,
 718                           struct in6_addr **daddr)
 719 {
 720         if (opt->srcrt) {
 721                 ipv6_push_rthdr(skb, proto, opt->srcrt, daddr);
 722                 /*
 723                  * IPV6_RTHDRDSTOPTS is ignored
 724                  * unless IPV6_RTHDR is set (RFC3542).
 725                  */
 726                 if (opt->dst0opt)
 727                         ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
 728         }
 729         if (opt->hopopt)
 730                 ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
 731 }
 732 EXPORT_SYMBOL(ipv6_push_nfrag_opts);
 733
 734 void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
 735 {
 736         if (opt->dst1opt)
 737                 ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
 738 }
 739
 740 struct ipv6_txoptions *
 741 ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
 742 {
 743         struct ipv6_txoptions *opt2;
 744
 745         opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
 746         if (opt2) {
 747                 long dif = (char *)opt2 - (char *)opt;
 748                 memcpy(opt2, opt, opt->tot_len);
 749                 if (opt2->hopopt)
 750                         *((char **)&opt2->hopopt) += dif;
 751                 if (opt2->dst0opt)
 752                         *((char **)&opt2->dst0opt) += dif;
 753                 if (opt2->dst1opt)
 754                         *((char **)&opt2->dst1opt) += dif;
 755                 if (opt2->srcrt)
 756                         *((char **)&opt2->srcrt) += dif;
 757                 atomic_set(&opt2->refcnt, 1);
 758         }
 759         return opt2;
 760 }
 761 EXPORT_SYMBOL_GPL(ipv6_dup_options);
 762
 763 static int ipv6_renew_option(void *ohdr,
 764                              struct ipv6_opt_hdr __user *newopt, int newoptlen,
 765                              int inherit,
 766                              struct ipv6_opt_hdr **hdr,
 767                              char **p)
 768 {
 769         if (inherit) {
 770                 if (ohdr) {
 771                         memcpy(*p, ohdr, ipv6_optlen((struct ipv6_opt_hdr *)ohdr));
 772                         *hdr = (struct ipv6_opt_hdr *)*p;
 773                         *p += CMSG_ALIGN(ipv6_optlen(*hdr));
 774                 }
 775         } else {
 776                 if (newopt) {
 777                         if (copy_from_user(*p, newopt, newoptlen))
 778                                 return -EFAULT;
 779                         *hdr = (struct ipv6_opt_hdr *)*p;
 780                         if (ipv6_optlen(*hdr) > newoptlen)
 781                                 return -EINVAL;
 782                         *p += CMSG_ALIGN(newoptlen);
 783                 }
 784         }
 785         return 0;
 786 }
 787
 788 /**
 789  * ipv6_renew_options - replace a specific ext hdr with a new one.
 790  *
 791  * @sk: sock from which to allocate memory
 792  * @opt: original options
 793  * @newtype: option type to replace in @opt
 794  * @newopt: new option of type @newtype to replace (user-mem)
 795  * @newoptlen: length of @newopt
 796  *
 797  * Returns a new set of options which is a copy of @opt with the
 798  * option type @newtype replaced with @newopt.
 799  *
 800  * @opt may be NULL, in which case a new set of options is returned
 801  * containing just @newopt.
 802  *
 803  * @newopt may be NULL, in which case the specified option type is
 804  * not copied into the new set of options.
 805  *
 806  * The new set of options is allocated from the socket option memory
 807  * buffer of @sk.
 808  */
 809 struct ipv6_txoptions *
 810 ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
 811                    int newtype,
 812                    struct ipv6_opt_hdr __user *newopt, int newoptlen)
 813 {
 814         int tot_len = 0;
 815         char *p;
 816         struct ipv6_txoptions *opt2;
 817         int err;
 818
 819         if (opt) {
 820                 if (newtype != IPV6_HOPOPTS && opt->hopopt)
 821                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
 822                 if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
 823                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
 824                 if (newtype != IPV6_RTHDR && opt->srcrt)
 825                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
 826                 if (newtype != IPV6_DSTOPTS && opt->dst1opt)
 827                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
 828         }
 829
 830         if (newopt && newoptlen)
 831                 tot_len += CMSG_ALIGN(newoptlen);
 832
 833         if (!tot_len)
 834                 return NULL;
 835
 836         tot_len += sizeof(*opt2);
 837         opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
 838         if (!opt2)
 839                 return ERR_PTR(-ENOBUFS);
 840
 841         memset(opt2, 0, tot_len);
 842         atomic_set(&opt2->refcnt, 1);
 843         opt2->tot_len = tot_len;
 844         p = (char *)(opt2 + 1);
 845
 846         err = ipv6_renew_option(opt ? opt->hopopt : NULL, newopt, newoptlen,
 847                                 newtype != IPV6_HOPOPTS,
 848                                 &opt2->hopopt, &p);
 849         if (err)
 850                 goto out;
 851
 852         err = ipv6_renew_option(opt ? opt->dst0opt : NULL, newopt, newoptlen,
 853                                 newtype != IPV6_RTHDRDSTOPTS,
 854                                 &opt2->dst0opt, &p);
 855         if (err)
 856                 goto out;
 857
 858         err = ipv6_renew_option(opt ? opt->srcrt : NULL, newopt, newoptlen,
 859                                 newtype != IPV6_RTHDR,
 860                                 (struct ipv6_opt_hdr **)&opt2->srcrt, &p);
 861         if (err)
 862                 goto out;
 863
 864         err = ipv6_renew_option(opt ? opt->dst1opt : NULL, newopt, newoptlen,
 865                                 newtype != IPV6_DSTOPTS,
 866                                 &opt2->dst1opt, &p);
 867         if (err)
 868                 goto out;
 869
 870         opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
 871                           (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
 872                           (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
 873         opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
 874
 875         return opt2;
 876 out:
 877         sock_kfree_s(sk, opt2, opt2->tot_len);
 878         return ERR_PTR(err);
 879 }
 880
 881 /**
 882  * ipv6_renew_options_kern - replace a specific ext hdr with a new one.
 883  *
 884  * @sk: sock from which to allocate memory
 885  * @opt: original options
 886  * @newtype: option type to replace in @opt
 887  * @newopt: new option of type @newtype to replace (kernel-mem)
 888  * @newoptlen: length of @newopt
 889  *
 890  * See ipv6_renew_options().  The difference is that @newopt is
 891  * kernel memory, rather than user memory.
 892  */
 893 struct ipv6_txoptions *
 894 ipv6_renew_options_kern(struct sock *sk, struct ipv6_txoptions *opt,
 895                         int newtype, struct ipv6_opt_hdr *newopt,
 896                         int newoptlen)
 897 {
 898         struct ipv6_txoptions *ret_val;
 899         const mm_segment_t old_fs = get_fs();
 900
 901         set_fs(KERNEL_DS);
 902         ret_val = ipv6_renew_options(sk, opt, newtype,
 903                                      (struct ipv6_opt_hdr __user *)newopt,
 904                                      newoptlen);
 905         set_fs(old_fs);
 906         return ret_val;
 907 }
 908
 909 struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space,
 910                                           struct ipv6_txoptions *opt)
 911 {
 912         /*
 913          * ignore the dest before srcrt unless srcrt is being included.
 914          * --yoshfuji
 915          */
 916         if (opt && opt->dst0opt && !opt->srcrt) {
 917                 if (opt_space != opt) {
 918                         memcpy(opt_space, opt, sizeof(*opt_space));
 919                         opt = opt_space;
 920                 }
 921                 opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
 922                 opt->dst0opt = NULL;
 923         }
 924
 925         return opt;
 926 }
 927 EXPORT_SYMBOL_GPL(ipv6_fixup_options);
 928
 929 /**
 930  * fl6_update_dst - update flowi destination address with info given
 931  *                  by srcrt option, if any.
 932  *
 933  * @fl6: flowi6 for which daddr is to be updated
 934  * @opt: struct ipv6_txoptions in which to look for srcrt opt
 935  * @orig: copy of original daddr address if modified
 936  *
 937  * Returns NULL if no txoptions or no srcrt, otherwise returns orig
 938  * and initial value of fl6->daddr set in orig
 939  */
 940 struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
 941                                 const struct ipv6_txoptions *opt,
 942                                 struct in6_addr *orig)
 943 {
 944         if (!opt || !opt->srcrt)
 945                 return NULL;
 946
 947         *orig = fl6->daddr;
 948         fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr;
 949         return orig;
 950 }
 951 EXPORT_SYMBOL_GPL(fl6_update_dst);