linux/net/ipv6/exthdrs.c
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   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
  60struct 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
  71static 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
  97static 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;
 174bad:
 175        kfree_skb(skb);
 176        return false;
 177}
 178
 179/*****************************
 180  Destination options header.
 181 *****************************/
 182
 183#if IS_ENABLED(CONFIG_IPV6_MIP6)
 184static 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
 246static 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
 256static 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() */
 299static 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
 334looped_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
 478unknown_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
 485static const struct inet6_protocol rthdr_protocol = {
 486        .handler        =       ipv6_rthdr_rcv,
 487        .flags          =       INET6_PROTO_NOPOLICY,
 488};
 489
 490static const struct inet6_protocol destopt_protocol = {
 491        .handler        =       ipv6_destopt_rcv,
 492        .flags          =       INET6_PROTO_NOPOLICY,
 493};
 494
 495static const struct inet6_protocol nodata_protocol = {
 496        .handler        =       dst_discard,
 497        .flags          =       INET6_PROTO_NOPOLICY,
 498};
 499
 500int __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
 516out:
 517        return ret;
 518out_destopt:
 519        inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 520out_rthdr:
 521        inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 522        goto out;
 523};
 524
 525void 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 */
 539static 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
 544static 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
 551static 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)->flags |= IP6SKB_ROUTERALERT;
 557                memcpy(&IP6CB(skb)->ra, nh + optoff + 2, sizeof(IP6CB(skb)->ra));
 558                return true;
 559        }
 560        LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_ra: wrong RA length %d\n",
 561                       nh[optoff + 1]);
 562        kfree_skb(skb);
 563        return false;
 564}
 565
 566/* Jumbo payload */
 567
 568static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
 569{
 570        const unsigned char *nh = skb_network_header(skb);
 571        struct net *net = ipv6_skb_net(skb);
 572        u32 pkt_len;
 573
 574        if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
 575                LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
 576                               nh[optoff+1]);
 577                IP6_INC_STATS_BH(net, ipv6_skb_idev(skb),
 578                                 IPSTATS_MIB_INHDRERRORS);
 579                goto drop;
 580        }
 581
 582        pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
 583        if (pkt_len <= IPV6_MAXPLEN) {
 584                IP6_INC_STATS_BH(net, ipv6_skb_idev(skb),
 585                                 IPSTATS_MIB_INHDRERRORS);
 586                icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2);
 587                return false;
 588        }
 589        if (ipv6_hdr(skb)->payload_len) {
 590                IP6_INC_STATS_BH(net, ipv6_skb_idev(skb),
 591                                 IPSTATS_MIB_INHDRERRORS);
 592                icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff);
 593                return false;
 594        }
 595
 596        if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
 597                IP6_INC_STATS_BH(net, ipv6_skb_idev(skb),
 598                                 IPSTATS_MIB_INTRUNCATEDPKTS);
 599                goto drop;
 600        }
 601
 602        if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 603                goto drop;
 604
 605        return true;
 606
 607drop:
 608        kfree_skb(skb);
 609        return false;
 610}
 611
 612static const struct tlvtype_proc tlvprochopopt_lst[] = {
 613        {
 614                .type   = IPV6_TLV_ROUTERALERT,
 615                .func   = ipv6_hop_ra,
 616        },
 617        {
 618                .type   = IPV6_TLV_JUMBO,
 619                .func   = ipv6_hop_jumbo,
 620        },
 621        { -1, }
 622};
 623
 624int ipv6_parse_hopopts(struct sk_buff *skb)
 625{
 626        struct inet6_skb_parm *opt = IP6CB(skb);
 627
 628        /*
 629         * skb_network_header(skb) is equal to skb->data, and
 630         * skb_network_header_len(skb) is always equal to
 631         * sizeof(struct ipv6hdr) by definition of
 632         * hop-by-hop options.
 633         */
 634        if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
 635            !pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
 636                                 ((skb_transport_header(skb)[1] + 1) << 3)))) {
 637                kfree_skb(skb);
 638                return -1;
 639        }
 640
 641        opt->hop = sizeof(struct ipv6hdr);
 642        if (ip6_parse_tlv(tlvprochopopt_lst, skb)) {
 643                skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
 644                opt = IP6CB(skb);
 645                opt->nhoff = sizeof(struct ipv6hdr);
 646                return 1;
 647        }
 648        return -1;
 649}
 650
 651/*
 652 *      Creating outbound headers.
 653 *
 654 *      "build" functions work when skb is filled from head to tail (datagram)
 655 *      "push"  functions work when headers are added from tail to head (tcp)
 656 *
 657 *      In both cases we assume, that caller reserved enough room
 658 *      for headers.
 659 */
 660
 661static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
 662                            struct ipv6_rt_hdr *opt,
 663                            struct in6_addr **addr_p)
 664{
 665        struct rt0_hdr *phdr, *ihdr;
 666        int hops;
 667
 668        ihdr = (struct rt0_hdr *) opt;
 669
 670        phdr = (struct rt0_hdr *) skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
 671        memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
 672
 673        hops = ihdr->rt_hdr.hdrlen >> 1;
 674
 675        if (hops > 1)
 676                memcpy(phdr->addr, ihdr->addr + 1,
 677                       (hops - 1) * sizeof(struct in6_addr));
 678
 679        phdr->addr[hops - 1] = **addr_p;
 680        *addr_p = ihdr->addr;
 681
 682        phdr->rt_hdr.nexthdr = *proto;
 683        *proto = NEXTHDR_ROUTING;
 684}
 685
 686static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
 687{
 688        struct ipv6_opt_hdr *h = (struct ipv6_opt_hdr *)skb_push(skb, ipv6_optlen(opt));
 689
 690        memcpy(h, opt, ipv6_optlen(opt));
 691        h->nexthdr = *proto;
 692        *proto = type;
 693}
 694
 695void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
 696                          u8 *proto,
 697                          struct in6_addr **daddr)
 698{
 699        if (opt->srcrt) {
 700                ipv6_push_rthdr(skb, proto, opt->srcrt, daddr);
 701                /*
 702                 * IPV6_RTHDRDSTOPTS is ignored
 703                 * unless IPV6_RTHDR is set (RFC3542).
 704                 */
 705                if (opt->dst0opt)
 706                        ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
 707        }
 708        if (opt->hopopt)
 709                ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
 710}
 711EXPORT_SYMBOL(ipv6_push_nfrag_opts);
 712
 713void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
 714{
 715        if (opt->dst1opt)
 716                ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
 717}
 718
 719struct ipv6_txoptions *
 720ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
 721{
 722        struct ipv6_txoptions *opt2;
 723
 724        opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
 725        if (opt2) {
 726                long dif = (char *)opt2 - (char *)opt;
 727                memcpy(opt2, opt, opt->tot_len);
 728                if (opt2->hopopt)
 729                        *((char **)&opt2->hopopt) += dif;
 730                if (opt2->dst0opt)
 731                        *((char **)&opt2->dst0opt) += dif;
 732                if (opt2->dst1opt)
 733                        *((char **)&opt2->dst1opt) += dif;
 734                if (opt2->srcrt)
 735                        *((char **)&opt2->srcrt) += dif;
 736        }
 737        return opt2;
 738}
 739EXPORT_SYMBOL_GPL(ipv6_dup_options);
 740
 741static int ipv6_renew_option(void *ohdr,
 742                             struct ipv6_opt_hdr __user *newopt, int newoptlen,
 743                             int inherit,
 744                             struct ipv6_opt_hdr **hdr,
 745                             char **p)
 746{
 747        if (inherit) {
 748                if (ohdr) {
 749                        memcpy(*p, ohdr, ipv6_optlen((struct ipv6_opt_hdr *)ohdr));
 750                        *hdr = (struct ipv6_opt_hdr *)*p;
 751                        *p += CMSG_ALIGN(ipv6_optlen(*hdr));
 752                }
 753        } else {
 754                if (newopt) {
 755                        if (copy_from_user(*p, newopt, newoptlen))
 756                                return -EFAULT;
 757                        *hdr = (struct ipv6_opt_hdr *)*p;
 758                        if (ipv6_optlen(*hdr) > newoptlen)
 759                                return -EINVAL;
 760                        *p += CMSG_ALIGN(newoptlen);
 761                }
 762        }
 763        return 0;
 764}
 765
 766struct ipv6_txoptions *
 767ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
 768                   int newtype,
 769                   struct ipv6_opt_hdr __user *newopt, int newoptlen)
 770{
 771        int tot_len = 0;
 772        char *p;
 773        struct ipv6_txoptions *opt2;
 774        int err;
 775
 776        if (opt) {
 777                if (newtype != IPV6_HOPOPTS && opt->hopopt)
 778                        tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
 779                if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
 780                        tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
 781                if (newtype != IPV6_RTHDR && opt->srcrt)
 782                        tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
 783                if (newtype != IPV6_DSTOPTS && opt->dst1opt)
 784                        tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
 785        }
 786
 787        if (newopt && newoptlen)
 788                tot_len += CMSG_ALIGN(newoptlen);
 789
 790        if (!tot_len)
 791                return NULL;
 792
 793        tot_len += sizeof(*opt2);
 794        opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
 795        if (!opt2)
 796                return ERR_PTR(-ENOBUFS);
 797
 798        memset(opt2, 0, tot_len);
 799
 800        opt2->tot_len = tot_len;
 801        p = (char *)(opt2 + 1);
 802
 803        err = ipv6_renew_option(opt ? opt->hopopt : NULL, newopt, newoptlen,
 804                                newtype != IPV6_HOPOPTS,
 805                                &opt2->hopopt, &p);
 806        if (err)
 807                goto out;
 808
 809        err = ipv6_renew_option(opt ? opt->dst0opt : NULL, newopt, newoptlen,
 810                                newtype != IPV6_RTHDRDSTOPTS,
 811                                &opt2->dst0opt, &p);
 812        if (err)
 813                goto out;
 814
 815        err = ipv6_renew_option(opt ? opt->srcrt : NULL, newopt, newoptlen,
 816                                newtype != IPV6_RTHDR,
 817                                (struct ipv6_opt_hdr **)&opt2->srcrt, &p);
 818        if (err)
 819                goto out;
 820
 821        err = ipv6_renew_option(opt ? opt->dst1opt : NULL, newopt, newoptlen,
 822                                newtype != IPV6_DSTOPTS,
 823                                &opt2->dst1opt, &p);
 824        if (err)
 825                goto out;
 826
 827        opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
 828                          (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
 829                          (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
 830        opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
 831
 832        return opt2;
 833out:
 834        sock_kfree_s(sk, opt2, opt2->tot_len);
 835        return ERR_PTR(err);
 836}
 837
 838struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space,
 839                                          struct ipv6_txoptions *opt)
 840{
 841        /*
 842         * ignore the dest before srcrt unless srcrt is being included.
 843         * --yoshfuji
 844         */
 845        if (opt && opt->dst0opt && !opt->srcrt) {
 846                if (opt_space != opt) {
 847                        memcpy(opt_space, opt, sizeof(*opt_space));
 848                        opt = opt_space;
 849                }
 850                opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
 851                opt->dst0opt = NULL;
 852        }
 853
 854        return opt;
 855}
 856EXPORT_SYMBOL_GPL(ipv6_fixup_options);
 857
 858/**
 859 * fl6_update_dst - update flowi destination address with info given
 860 *                  by srcrt option, if any.
 861 *
 862 * @fl6: flowi6 for which daddr is to be updated
 863 * @opt: struct ipv6_txoptions in which to look for srcrt opt
 864 * @orig: copy of original daddr address if modified
 865 *
 866 * Returns NULL if no txoptions or no srcrt, otherwise returns orig
 867 * and initial value of fl6->daddr set in orig
 868 */
 869struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
 870                                const struct ipv6_txoptions *opt,
 871                                struct in6_addr *orig)
 872{
 873        if (!opt || !opt->srcrt)
 874                return NULL;
 875
 876        *orig = fl6->daddr;
 877        fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr;
 878        return orig;
 879}
 880EXPORT_SYMBOL_GPL(fl6_update_dst);
 881