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 <linux/uaccess.h>
  51
  52/*
  53 *      Parsing tlv encoded headers.
  54 *
  55 *      Parsing function "func" returns true, if parsing succeed
  56 *      and false, if it failed.
  57 *      It MUST NOT touch skb->h.
  58 */
  59
  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
 166        if (len == 0)
 167                return true;
 168bad:
 169        kfree_skb(skb);
 170        return false;
 171}
 172
 173/*****************************
 174  Destination options header.
 175 *****************************/
 176
 177#if IS_ENABLED(CONFIG_IPV6_MIP6)
 178static bool ipv6_dest_hao(struct sk_buff *skb, int optoff)
 179{
 180        struct ipv6_destopt_hao *hao;
 181        struct inet6_skb_parm *opt = IP6CB(skb);
 182        struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 183        struct in6_addr tmp_addr;
 184        int ret;
 185
 186        if (opt->dsthao) {
 187                net_dbg_ratelimited("hao duplicated\n");
 188                goto discard;
 189        }
 190        opt->dsthao = opt->dst1;
 191        opt->dst1 = 0;
 192
 193        hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) + optoff);
 194
 195        if (hao->length != 16) {
 196                net_dbg_ratelimited("hao invalid option length = %d\n",
 197                                    hao->length);
 198                goto discard;
 199        }
 200
 201        if (!(ipv6_addr_type(&hao->addr) & IPV6_ADDR_UNICAST)) {
 202                net_dbg_ratelimited("hao is not an unicast addr: %pI6\n",
 203                                    &hao->addr);
 204                goto discard;
 205        }
 206
 207        ret = xfrm6_input_addr(skb, (xfrm_address_t *)&ipv6h->daddr,
 208                               (xfrm_address_t *)&hao->addr, IPPROTO_DSTOPTS);
 209        if (unlikely(ret < 0))
 210                goto discard;
 211
 212        if (skb_cloned(skb)) {
 213                if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 214                        goto discard;
 215
 216                /* update all variable using below by copied skbuff */
 217                hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) +
 218                                                  optoff);
 219                ipv6h = ipv6_hdr(skb);
 220        }
 221
 222        if (skb->ip_summed == CHECKSUM_COMPLETE)
 223                skb->ip_summed = CHECKSUM_NONE;
 224
 225        tmp_addr = ipv6h->saddr;
 226        ipv6h->saddr = hao->addr;
 227        hao->addr = tmp_addr;
 228
 229        if (skb->tstamp.tv64 == 0)
 230                __net_timestamp(skb);
 231
 232        return true;
 233
 234 discard:
 235        kfree_skb(skb);
 236        return false;
 237}
 238#endif
 239
 240static const struct tlvtype_proc tlvprocdestopt_lst[] = {
 241#if IS_ENABLED(CONFIG_IPV6_MIP6)
 242        {
 243                .type   = IPV6_TLV_HAO,
 244                .func   = ipv6_dest_hao,
 245        },
 246#endif
 247        {-1,                    NULL}
 248};
 249
 250static int ipv6_destopt_rcv(struct sk_buff *skb)
 251{
 252        struct inet6_skb_parm *opt = IP6CB(skb);
 253#if IS_ENABLED(CONFIG_IPV6_MIP6)
 254        __u16 dstbuf;
 255#endif
 256        struct dst_entry *dst = skb_dst(skb);
 257
 258        if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 259            !pskb_may_pull(skb, (skb_transport_offset(skb) +
 260                                 ((skb_transport_header(skb)[1] + 1) << 3)))) {
 261                IP6_INC_STATS_BH(dev_net(dst->dev), ip6_dst_idev(dst),
 262                                 IPSTATS_MIB_INHDRERRORS);
 263                kfree_skb(skb);
 264                return -1;
 265        }
 266
 267        opt->lastopt = opt->dst1 = skb_network_header_len(skb);
 268#if IS_ENABLED(CONFIG_IPV6_MIP6)
 269        dstbuf = opt->dst1;
 270#endif
 271
 272        if (ip6_parse_tlv(tlvprocdestopt_lst, skb)) {
 273                skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
 274                opt = IP6CB(skb);
 275#if IS_ENABLED(CONFIG_IPV6_MIP6)
 276                opt->nhoff = dstbuf;
 277#else
 278                opt->nhoff = opt->dst1;
 279#endif
 280                return 1;
 281        }
 282
 283        IP6_INC_STATS_BH(dev_net(dst->dev),
 284                         ip6_dst_idev(dst), IPSTATS_MIB_INHDRERRORS);
 285        return -1;
 286}
 287
 288/********************************
 289  Routing header.
 290 ********************************/
 291
 292/* called with rcu_read_lock() */
 293static int ipv6_rthdr_rcv(struct sk_buff *skb)
 294{
 295        struct inet6_skb_parm *opt = IP6CB(skb);
 296        struct in6_addr *addr = NULL;
 297        struct in6_addr daddr;
 298        struct inet6_dev *idev;
 299        int n, i;
 300        struct ipv6_rt_hdr *hdr;
 301        struct rt0_hdr *rthdr;
 302        struct net *net = dev_net(skb->dev);
 303        int accept_source_route = net->ipv6.devconf_all->accept_source_route;
 304
 305        idev = __in6_dev_get(skb->dev);
 306        if (idev && accept_source_route > idev->cnf.accept_source_route)
 307                accept_source_route = idev->cnf.accept_source_route;
 308
 309        if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 310            !pskb_may_pull(skb, (skb_transport_offset(skb) +
 311                                 ((skb_transport_header(skb)[1] + 1) << 3)))) {
 312                IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 313                                 IPSTATS_MIB_INHDRERRORS);
 314                kfree_skb(skb);
 315                return -1;
 316        }
 317
 318        hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 319
 320        if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ||
 321            skb->pkt_type != PACKET_HOST) {
 322                IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 323                                 IPSTATS_MIB_INADDRERRORS);
 324                kfree_skb(skb);
 325                return -1;
 326        }
 327
 328looped_back:
 329        if (hdr->segments_left == 0) {
 330                switch (hdr->type) {
 331#if IS_ENABLED(CONFIG_IPV6_MIP6)
 332                case IPV6_SRCRT_TYPE_2:
 333                        /* Silently discard type 2 header unless it was
 334                         * processed by own
 335                         */
 336                        if (!addr) {
 337                                IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 338                                                 IPSTATS_MIB_INADDRERRORS);
 339                                kfree_skb(skb);
 340                                return -1;
 341                        }
 342                        break;
 343#endif
 344                default:
 345                        break;
 346                }
 347
 348                opt->lastopt = opt->srcrt = skb_network_header_len(skb);
 349                skb->transport_header += (hdr->hdrlen + 1) << 3;
 350                opt->dst0 = opt->dst1;
 351                opt->dst1 = 0;
 352                opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
 353                return 1;
 354        }
 355
 356        switch (hdr->type) {
 357#if IS_ENABLED(CONFIG_IPV6_MIP6)
 358        case IPV6_SRCRT_TYPE_2:
 359                if (accept_source_route < 0)
 360                        goto unknown_rh;
 361                /* Silently discard invalid RTH type 2 */
 362                if (hdr->hdrlen != 2 || hdr->segments_left != 1) {
 363                        IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 364                                         IPSTATS_MIB_INHDRERRORS);
 365                        kfree_skb(skb);
 366                        return -1;
 367                }
 368                break;
 369#endif
 370        default:
 371                goto unknown_rh;
 372        }
 373
 374        /*
 375         *      This is the routing header forwarding algorithm from
 376         *      RFC 2460, page 16.
 377         */
 378
 379        n = hdr->hdrlen >> 1;
 380
 381        if (hdr->segments_left > n) {
 382                IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 383                                 IPSTATS_MIB_INHDRERRORS);
 384                icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 385                                  ((&hdr->segments_left) -
 386                                   skb_network_header(skb)));
 387                return -1;
 388        }
 389
 390        /* We are about to mangle packet header. Be careful!
 391           Do not damage packets queued somewhere.
 392         */
 393        if (skb_cloned(skb)) {
 394                /* the copy is a forwarded packet */
 395                if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
 396                        IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 397                                         IPSTATS_MIB_OUTDISCARDS);
 398                        kfree_skb(skb);
 399                        return -1;
 400                }
 401                hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 402        }
 403
 404        if (skb->ip_summed == CHECKSUM_COMPLETE)
 405                skb->ip_summed = CHECKSUM_NONE;
 406
 407        i = n - --hdr->segments_left;
 408
 409        rthdr = (struct rt0_hdr *) hdr;
 410        addr = rthdr->addr;
 411        addr += i - 1;
 412
 413        switch (hdr->type) {
 414#if IS_ENABLED(CONFIG_IPV6_MIP6)
 415        case IPV6_SRCRT_TYPE_2:
 416                if (xfrm6_input_addr(skb, (xfrm_address_t *)addr,
 417                                     (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 418                                     IPPROTO_ROUTING) < 0) {
 419                        IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 420                                         IPSTATS_MIB_INADDRERRORS);
 421                        kfree_skb(skb);
 422                        return -1;
 423                }
 424                if (!ipv6_chk_home_addr(dev_net(skb_dst(skb)->dev), addr)) {
 425                        IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 426                                         IPSTATS_MIB_INADDRERRORS);
 427                        kfree_skb(skb);
 428                        return -1;
 429                }
 430                break;
 431#endif
 432        default:
 433                break;
 434        }
 435
 436        if (ipv6_addr_is_multicast(addr)) {
 437                IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 438                                 IPSTATS_MIB_INADDRERRORS);
 439                kfree_skb(skb);
 440                return -1;
 441        }
 442
 443        daddr = *addr;
 444        *addr = ipv6_hdr(skb)->daddr;
 445        ipv6_hdr(skb)->daddr = daddr;
 446
 447        skb_dst_drop(skb);
 448        ip6_route_input(skb);
 449        if (skb_dst(skb)->error) {
 450                skb_push(skb, skb->data - skb_network_header(skb));
 451                dst_input(skb);
 452                return -1;
 453        }
 454
 455        if (skb_dst(skb)->dev->flags&IFF_LOOPBACK) {
 456                if (ipv6_hdr(skb)->hop_limit <= 1) {
 457                        IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 458                                         IPSTATS_MIB_INHDRERRORS);
 459                        icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
 460                                    0);
 461                        kfree_skb(skb);
 462                        return -1;
 463                }
 464                ipv6_hdr(skb)->hop_limit--;
 465                goto looped_back;
 466        }
 467
 468        skb_push(skb, skb->data - skb_network_header(skb));
 469        dst_input(skb);
 470        return -1;
 471
 472unknown_rh:
 473        IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS);
 474        icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 475                          (&hdr->type) - skb_network_header(skb));
 476        return -1;
 477}
 478
 479static const struct inet6_protocol rthdr_protocol = {
 480        .handler        =       ipv6_rthdr_rcv,
 481        .flags          =       INET6_PROTO_NOPOLICY,
 482};
 483
 484static const struct inet6_protocol destopt_protocol = {
 485        .handler        =       ipv6_destopt_rcv,
 486        .flags          =       INET6_PROTO_NOPOLICY,
 487};
 488
 489static const struct inet6_protocol nodata_protocol = {
 490        .handler        =       dst_discard,
 491        .flags          =       INET6_PROTO_NOPOLICY,
 492};
 493
 494int __init ipv6_exthdrs_init(void)
 495{
 496        int ret;
 497
 498        ret = inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 499        if (ret)
 500                goto out;
 501
 502        ret = inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 503        if (ret)
 504                goto out_rthdr;
 505
 506        ret = inet6_add_protocol(&nodata_protocol, IPPROTO_NONE);
 507        if (ret)
 508                goto out_destopt;
 509
 510out:
 511        return ret;
 512out_destopt:
 513        inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 514out_rthdr:
 515        inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 516        goto out;
 517};
 518
 519void ipv6_exthdrs_exit(void)
 520{
 521        inet6_del_protocol(&nodata_protocol, IPPROTO_NONE);
 522        inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 523        inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 524}
 525
 526/**********************************
 527  Hop-by-hop options.
 528 **********************************/
 529
 530/*
 531 * Note: we cannot rely on skb_dst(skb) before we assign it in ip6_route_input().
 532 */
 533static inline struct inet6_dev *ipv6_skb_idev(struct sk_buff *skb)
 534{
 535        return skb_dst(skb) ? ip6_dst_idev(skb_dst(skb)) : __in6_dev_get(skb->dev);
 536}
 537
 538static inline struct net *ipv6_skb_net(struct sk_buff *skb)
 539{
 540        return skb_dst(skb) ? dev_net(skb_dst(skb)->dev) : dev_net(skb->dev);
 541}
 542
 543/* Router Alert as of RFC 2711 */
 544
 545static bool ipv6_hop_ra(struct sk_buff *skb, int optoff)
 546{
 547        const unsigned char *nh = skb_network_header(skb);
 548
 549        if (nh[optoff + 1] == 2) {
 550                IP6CB(skb)->flags |= IP6SKB_ROUTERALERT;
 551                memcpy(&IP6CB(skb)->ra, nh + optoff + 2, sizeof(IP6CB(skb)->ra));
 552                return true;
 553        }
 554        net_dbg_ratelimited("ipv6_hop_ra: wrong RA length %d\n",
 555                            nh[optoff + 1]);
 556        kfree_skb(skb);
 557        return false;
 558}
 559
 560/* Jumbo payload */
 561
 562static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
 563{
 564        const unsigned char *nh = skb_network_header(skb);
 565        struct net *net = ipv6_skb_net(skb);
 566        u32 pkt_len;
 567
 568        if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
 569                net_dbg_ratelimited("ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
 570                                    nh[optoff+1]);
 571                IP6_INC_STATS_BH(net, ipv6_skb_idev(skb),
 572                                 IPSTATS_MIB_INHDRERRORS);
 573                goto drop;
 574        }
 575
 576        pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
 577        if (pkt_len <= IPV6_MAXPLEN) {
 578                IP6_INC_STATS_BH(net, ipv6_skb_idev(skb),
 579                                 IPSTATS_MIB_INHDRERRORS);
 580                icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2);
 581                return false;
 582        }
 583        if (ipv6_hdr(skb)->payload_len) {
 584                IP6_INC_STATS_BH(net, ipv6_skb_idev(skb),
 585                                 IPSTATS_MIB_INHDRERRORS);
 586                icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff);
 587                return false;
 588        }
 589
 590        if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
 591                IP6_INC_STATS_BH(net, ipv6_skb_idev(skb),
 592                                 IPSTATS_MIB_INTRUNCATEDPKTS);
 593                goto drop;
 594        }
 595
 596        if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 597                goto drop;
 598
 599        return true;
 600
 601drop:
 602        kfree_skb(skb);
 603        return false;
 604}
 605
 606static const struct tlvtype_proc tlvprochopopt_lst[] = {
 607        {
 608                .type   = IPV6_TLV_ROUTERALERT,
 609                .func   = ipv6_hop_ra,
 610        },
 611        {
 612                .type   = IPV6_TLV_JUMBO,
 613                .func   = ipv6_hop_jumbo,
 614        },
 615        { -1, }
 616};
 617
 618int ipv6_parse_hopopts(struct sk_buff *skb)
 619{
 620        struct inet6_skb_parm *opt = IP6CB(skb);
 621
 622        /*
 623         * skb_network_header(skb) is equal to skb->data, and
 624         * skb_network_header_len(skb) is always equal to
 625         * sizeof(struct ipv6hdr) by definition of
 626         * hop-by-hop options.
 627         */
 628        if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
 629            !pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
 630                                 ((skb_transport_header(skb)[1] + 1) << 3)))) {
 631                kfree_skb(skb);
 632                return -1;
 633        }
 634
 635        opt->hop = sizeof(struct ipv6hdr);
 636        if (ip6_parse_tlv(tlvprochopopt_lst, skb)) {
 637                skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3;
 638                opt = IP6CB(skb);
 639                opt->nhoff = sizeof(struct ipv6hdr);
 640                return 1;
 641        }
 642        return -1;
 643}
 644
 645/*
 646 *      Creating outbound headers.
 647 *
 648 *      "build" functions work when skb is filled from head to tail (datagram)
 649 *      "push"  functions work when headers are added from tail to head (tcp)
 650 *
 651 *      In both cases we assume, that caller reserved enough room
 652 *      for headers.
 653 */
 654
 655static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
 656                            struct ipv6_rt_hdr *opt,
 657                            struct in6_addr **addr_p)
 658{
 659        struct rt0_hdr *phdr, *ihdr;
 660        int hops;
 661
 662        ihdr = (struct rt0_hdr *) opt;
 663
 664        phdr = (struct rt0_hdr *) skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
 665        memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
 666
 667        hops = ihdr->rt_hdr.hdrlen >> 1;
 668
 669        if (hops > 1)
 670                memcpy(phdr->addr, ihdr->addr + 1,
 671                       (hops - 1) * sizeof(struct in6_addr));
 672
 673        phdr->addr[hops - 1] = **addr_p;
 674        *addr_p = ihdr->addr;
 675
 676        phdr->rt_hdr.nexthdr = *proto;
 677        *proto = NEXTHDR_ROUTING;
 678}
 679
 680static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
 681{
 682        struct ipv6_opt_hdr *h = (struct ipv6_opt_hdr *)skb_push(skb, ipv6_optlen(opt));
 683
 684        memcpy(h, opt, ipv6_optlen(opt));
 685        h->nexthdr = *proto;
 686        *proto = type;
 687}
 688
 689void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
 690                          u8 *proto,
 691                          struct in6_addr **daddr)
 692{
 693        if (opt->srcrt) {
 694                ipv6_push_rthdr(skb, proto, opt->srcrt, daddr);
 695                /*
 696                 * IPV6_RTHDRDSTOPTS is ignored
 697                 * unless IPV6_RTHDR is set (RFC3542).
 698                 */
 699                if (opt->dst0opt)
 700                        ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
 701        }
 702        if (opt->hopopt)
 703                ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
 704}
 705EXPORT_SYMBOL(ipv6_push_nfrag_opts);
 706
 707void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
 708{
 709        if (opt->dst1opt)
 710                ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
 711}
 712
 713struct ipv6_txoptions *
 714ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
 715{
 716        struct ipv6_txoptions *opt2;
 717
 718        opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
 719        if (opt2) {
 720                long dif = (char *)opt2 - (char *)opt;
 721                memcpy(opt2, opt, opt->tot_len);
 722                if (opt2->hopopt)
 723                        *((char **)&opt2->hopopt) += dif;
 724                if (opt2->dst0opt)
 725                        *((char **)&opt2->dst0opt) += dif;
 726                if (opt2->dst1opt)
 727                        *((char **)&opt2->dst1opt) += dif;
 728                if (opt2->srcrt)
 729                        *((char **)&opt2->srcrt) += dif;
 730        }
 731        return opt2;
 732}
 733EXPORT_SYMBOL_GPL(ipv6_dup_options);
 734
 735static int ipv6_renew_option(void *ohdr,
 736                             struct ipv6_opt_hdr __user *newopt, int newoptlen,
 737                             int inherit,
 738                             struct ipv6_opt_hdr **hdr,
 739                             char **p)
 740{
 741        if (inherit) {
 742                if (ohdr) {
 743                        memcpy(*p, ohdr, ipv6_optlen((struct ipv6_opt_hdr *)ohdr));
 744                        *hdr = (struct ipv6_opt_hdr *)*p;
 745                        *p += CMSG_ALIGN(ipv6_optlen(*hdr));
 746                }
 747        } else {
 748                if (newopt) {
 749                        if (copy_from_user(*p, newopt, newoptlen))
 750                                return -EFAULT;
 751                        *hdr = (struct ipv6_opt_hdr *)*p;
 752                        if (ipv6_optlen(*hdr) > newoptlen)
 753                                return -EINVAL;
 754                        *p += CMSG_ALIGN(newoptlen);
 755                }
 756        }
 757        return 0;
 758}
 759
 760struct ipv6_txoptions *
 761ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
 762                   int newtype,
 763                   struct ipv6_opt_hdr __user *newopt, int newoptlen)
 764{
 765        int tot_len = 0;
 766        char *p;
 767        struct ipv6_txoptions *opt2;
 768        int err;
 769
 770        if (opt) {
 771                if (newtype != IPV6_HOPOPTS && opt->hopopt)
 772                        tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
 773                if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
 774                        tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
 775                if (newtype != IPV6_RTHDR && opt->srcrt)
 776                        tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
 777                if (newtype != IPV6_DSTOPTS && opt->dst1opt)
 778                        tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
 779        }
 780
 781        if (newopt && newoptlen)
 782                tot_len += CMSG_ALIGN(newoptlen);
 783
 784        if (!tot_len)
 785                return NULL;
 786
 787        tot_len += sizeof(*opt2);
 788        opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
 789        if (!opt2)
 790                return ERR_PTR(-ENOBUFS);
 791
 792        memset(opt2, 0, tot_len);
 793
 794        opt2->tot_len = tot_len;
 795        p = (char *)(opt2 + 1);
 796
 797        err = ipv6_renew_option(opt ? opt->hopopt : NULL, newopt, newoptlen,
 798                                newtype != IPV6_HOPOPTS,
 799                                &opt2->hopopt, &p);
 800        if (err)
 801                goto out;
 802
 803        err = ipv6_renew_option(opt ? opt->dst0opt : NULL, newopt, newoptlen,
 804                                newtype != IPV6_RTHDRDSTOPTS,
 805                                &opt2->dst0opt, &p);
 806        if (err)
 807                goto out;
 808
 809        err = ipv6_renew_option(opt ? opt->srcrt : NULL, newopt, newoptlen,
 810                                newtype != IPV6_RTHDR,
 811                                (struct ipv6_opt_hdr **)&opt2->srcrt, &p);
 812        if (err)
 813                goto out;
 814
 815        err = ipv6_renew_option(opt ? opt->dst1opt : NULL, newopt, newoptlen,
 816                                newtype != IPV6_DSTOPTS,
 817                                &opt2->dst1opt, &p);
 818        if (err)
 819                goto out;
 820
 821        opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
 822                          (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
 823                          (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
 824        opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
 825
 826        return opt2;
 827out:
 828        sock_kfree_s(sk, opt2, opt2->tot_len);
 829        return ERR_PTR(err);
 830}
 831
 832struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space,
 833                                          struct ipv6_txoptions *opt)
 834{
 835        /*
 836         * ignore the dest before srcrt unless srcrt is being included.
 837         * --yoshfuji
 838         */
 839        if (opt && opt->dst0opt && !opt->srcrt) {
 840                if (opt_space != opt) {
 841                        memcpy(opt_space, opt, sizeof(*opt_space));
 842                        opt = opt_space;
 843                }
 844                opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
 845                opt->dst0opt = NULL;
 846        }
 847
 848        return opt;
 849}
 850EXPORT_SYMBOL_GPL(ipv6_fixup_options);
 851
 852/**
 853 * fl6_update_dst - update flowi destination address with info given
 854 *                  by srcrt option, if any.
 855 *
 856 * @fl6: flowi6 for which daddr is to be updated
 857 * @opt: struct ipv6_txoptions in which to look for srcrt opt
 858 * @orig: copy of original daddr address if modified
 859 *
 860 * Returns NULL if no txoptions or no srcrt, otherwise returns orig
 861 * and initial value of fl6->daddr set in orig
 862 */
 863struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
 864                                const struct ipv6_txoptions *opt,
 865                                struct in6_addr *orig)
 866{
 867        if (!opt || !opt->srcrt)
 868                return NULL;
 869
 870        *orig = fl6->daddr;
 871        fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr;
 872        return orig;
 873}
 874EXPORT_SYMBOL_GPL(fl6_update_dst);
 875