net/ipv6/exthdrs.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      Extension Header handling for IPv6
   4  *      Linux INET6 implementation
   5  *
   6  *      Authors:
   7  *      Pedro Roque             <roque@di.fc.ul.pt>
   8  *      Andi Kleen              <ak@muc.de>
   9  *      Alexey Kuznetsov        <kuznet@ms2.inr.ac.ru>
  10  */
  11
  12 /* Changes:
  13  *      yoshfuji                : ensure not to overrun while parsing
  14  *                                tlv options.
  15  *      Mitsuru KANDA @USAGI and: Remove ipv6_parse_exthdrs().
  16  *      YOSHIFUJI Hideaki @USAGI  Register inbound extension header
  17  *                                handlers as inet6_protocol{}.
  18  */
  19
  20 #include <linux/errno.h>
  21 #include <linux/types.h>
  22 #include <linux/socket.h>
  23 #include <linux/sockios.h>
  24 #include <linux/net.h>
  25 #include <linux/netdevice.h>
  26 #include <linux/in6.h>
  27 #include <linux/icmpv6.h>
  28 #include <linux/slab.h>
  29 #include <linux/export.h>
  30
  31 #include <net/dst.h>
  32 #include <net/sock.h>
  33 #include <net/snmp.h>
  34
  35 #include <net/ipv6.h>
  36 #include <net/protocol.h>
  37 #include <net/transp_v6.h>
  38 #include <net/rawv6.h>
  39 #include <net/ndisc.h>
  40 #include <net/ip6_route.h>
  41 #include <net/addrconf.h>
  42 #include <net/calipso.h>
  43 #if IS_ENABLED(CONFIG_IPV6_MIP6)
  44 #include <net/xfrm.h>
  45 #endif
  46 #include <linux/seg6.h>
  47 #include <net/seg6.h>
  48 #ifdef CONFIG_IPV6_SEG6_HMAC
  49 #include <net/seg6_hmac.h>
  50 #endif
  51
  52 #include <linux/uaccess.h>
  53
  54 /*
  55  *      Parsing tlv encoded headers.
  56  *
  57  *      Parsing function "func" returns true, if parsing succeed
  58  *      and false, if it failed.
  59  *      It MUST NOT touch skb->h.
  60  */
  61
  62 struct tlvtype_proc {
  63         int     type;
  64         bool    (*func)(struct sk_buff *skb, int offset);
  65 };
  66
  67 /*********************
  68   Generic functions
  69  *********************/
  70
  71 /* An unknown option is detected, decide what to do */
  72
  73 static bool ip6_tlvopt_unknown(struct sk_buff *skb, int optoff,
  74                                bool disallow_unknowns)
  75 {
  76         if (disallow_unknowns) {
  77                 /* If unknown TLVs are disallowed by configuration
  78                  * then always silently drop packet. Note this also
  79                  * means no ICMP parameter problem is sent which
  80                  * could be a good property to mitigate a reflection DOS
  81                  * attack.
  82                  */
  83
  84                 goto drop;
  85         }
  86
  87         switch ((skb_network_header(skb)[optoff] & 0xC0) >> 6) {
  88         case 0: /* ignore */
  89                 return true;
  90
  91         case 1: /* drop packet */
  92                 break;
  93
  94         case 3: /* Send ICMP if not a multicast address and drop packet */
  95                 /* Actually, it is redundant check. icmp_send
  96                    will recheck in any case.
  97                  */
  98                 if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr))
  99                         break;
 100                 /* fall through */
 101         case 2: /* send ICMP PARM PROB regardless and drop packet */
 102                 icmpv6_param_prob(skb, ICMPV6_UNK_OPTION, optoff);
 103                 return false;
 104         }
 105
 106 drop:
 107         kfree_skb(skb);
 108         return false;
 109 }
 110
 111 /* Parse tlv encoded option header (hop-by-hop or destination) */
 112
 113 static bool ip6_parse_tlv(const struct tlvtype_proc *procs,
 114                           struct sk_buff *skb,
 115                           int max_count)
 116 {
 117         int len = (skb_transport_header(skb)[1] + 1) << 3;
 118         const unsigned char *nh = skb_network_header(skb);
 119         int off = skb_network_header_len(skb);
 120         const struct tlvtype_proc *curr;
 121         bool disallow_unknowns = false;
 122         int tlv_count = 0;
 123         int padlen = 0;
 124
 125         if (unlikely(max_count < 0)) {
 126                 disallow_unknowns = true;
 127                 max_count = -max_count;
 128         }
 129
 130         if (skb_transport_offset(skb) + len > skb_headlen(skb))
 131                 goto bad;
 132
 133         off += 2;
 134         len -= 2;
 135
 136         while (len > 0) {
 137                 int optlen = nh[off + 1] + 2;
 138                 int i;
 139
 140                 switch (nh[off]) {
 141                 case IPV6_TLV_PAD1:
 142                         optlen = 1;
 143                         padlen++;
 144                         if (padlen > 7)
 145                                 goto bad;
 146                         break;
 147
 148                 case IPV6_TLV_PADN:
 149                         /* RFC 2460 states that the purpose of PadN is
 150                          * to align the containing header to multiples
 151                          * of 8. 7 is therefore the highest valid value.
 152                          * See also RFC 4942, Section 2.1.9.5.
 153                          */
 154                         padlen += optlen;
 155                         if (padlen > 7)
 156                                 goto bad;
 157                         /* RFC 4942 recommends receiving hosts to
 158                          * actively check PadN payload to contain
 159                          * only zeroes.
 160                          */
 161                         for (i = 2; i < optlen; i++) {
 162                                 if (nh[off + i] != 0)
 163                                         goto bad;
 164                         }
 165                         break;
 166
 167                 default: /* Other TLV code so scan list */
 168                         if (optlen > len)
 169                                 goto bad;
 170
 171                         tlv_count++;
 172                         if (tlv_count > max_count)
 173                                 goto bad;
 174
 175                         for (curr = procs; curr->type >= 0; curr++) {
 176                                 if (curr->type == nh[off]) {
 177                                         /* type specific length/alignment
 178                                            checks will be performed in the
 179                                            func(). */
 180                                         if (curr->func(skb, off) == false)
 181                                                 return false;
 182                                         break;
 183                                 }
 184                         }
 185                         if (curr->type < 0 &&
 186                             !ip6_tlvopt_unknown(skb, off, disallow_unknowns))
 187                                 return false;
 188
 189                         padlen = 0;
 190                         break;
 191                 }
 192                 off += optlen;
 193                 len -= optlen;
 194         }
 195
 196         if (len == 0)
 197                 return true;
 198 bad:
 199         kfree_skb(skb);
 200         return false;
 201 }
 202
 203 /*****************************
 204   Destination options header.
 205  *****************************/
 206
 207 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 208 static bool ipv6_dest_hao(struct sk_buff *skb, int optoff)
 209 {
 210         struct ipv6_destopt_hao *hao;
 211         struct inet6_skb_parm *opt = IP6CB(skb);
 212         struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 213         int ret;
 214
 215         if (opt->dsthao) {
 216                 net_dbg_ratelimited("hao duplicated\n");
 217                 goto discard;
 218         }
 219         opt->dsthao = opt->dst1;
 220         opt->dst1 = 0;
 221
 222         hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) + optoff);
 223
 224         if (hao->length != 16) {
 225                 net_dbg_ratelimited("hao invalid option length = %d\n",
 226                                     hao->length);
 227                 goto discard;
 228         }
 229
 230         if (!(ipv6_addr_type(&hao->addr) & IPV6_ADDR_UNICAST)) {
 231                 net_dbg_ratelimited("hao is not an unicast addr: %pI6\n",
 232                                     &hao->addr);
 233                 goto discard;
 234         }
 235
 236         ret = xfrm6_input_addr(skb, (xfrm_address_t *)&ipv6h->daddr,
 237                                (xfrm_address_t *)&hao->addr, IPPROTO_DSTOPTS);
 238         if (unlikely(ret < 0))
 239                 goto discard;
 240
 241         if (skb_cloned(skb)) {
 242                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 243                         goto discard;
 244
 245                 /* update all variable using below by copied skbuff */
 246                 hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) +
 247                                                   optoff);
 248                 ipv6h = ipv6_hdr(skb);
 249         }
 250
 251         if (skb->ip_summed == CHECKSUM_COMPLETE)
 252                 skb->ip_summed = CHECKSUM_NONE;
 253
 254         swap(ipv6h->saddr, hao->addr);
 255
 256         if (skb->tstamp == 0)
 257                 __net_timestamp(skb);
 258
 259         return true;
 260
 261  discard:
 262         kfree_skb(skb);
 263         return false;
 264 }
 265 #endif
 266
 267 static const struct tlvtype_proc tlvprocdestopt_lst[] = {
 268 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 269         {
 270                 .type   = IPV6_TLV_HAO,
 271                 .func   = ipv6_dest_hao,
 272         },
 273 #endif
 274         {-1,                    NULL}
 275 };
 276
 277 static int ipv6_destopt_rcv(struct sk_buff *skb)
 278 {
 279         struct inet6_dev *idev = __in6_dev_get(skb->dev);
 280         struct inet6_skb_parm *opt = IP6CB(skb);
 281 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 282         __u16 dstbuf;
 283 #endif
 284         struct dst_entry *dst = skb_dst(skb);
 285         struct net *net = dev_net(skb->dev);
 286         int extlen;
 287
 288         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 289             !pskb_may_pull(skb, (skb_transport_offset(skb) +
 290                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 291                 __IP6_INC_STATS(dev_net(dst->dev), idev,
 292                                 IPSTATS_MIB_INHDRERRORS);
 293 fail_and_free:
 294                 kfree_skb(skb);
 295                 return -1;
 296         }
 297
 298         extlen = (skb_transport_header(skb)[1] + 1) << 3;
 299         if (extlen > net->ipv6.sysctl.max_dst_opts_len)
 300                 goto fail_and_free;
 301
 302         opt->lastopt = opt->dst1 = skb_network_header_len(skb);
 303 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 304         dstbuf = opt->dst1;
 305 #endif
 306
 307         if (ip6_parse_tlv(tlvprocdestopt_lst, skb,
 308                           init_net.ipv6.sysctl.max_dst_opts_cnt)) {
 309                 skb->transport_header += extlen;
 310                 opt = IP6CB(skb);
 311 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 312                 opt->nhoff = dstbuf;
 313 #else
 314                 opt->nhoff = opt->dst1;
 315 #endif
 316                 return 1;
 317         }
 318
 319         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 320         return -1;
 321 }
 322
 323 static void seg6_update_csum(struct sk_buff *skb)
 324 {
 325         struct ipv6_sr_hdr *hdr;
 326         struct in6_addr *addr;
 327         __be32 from, to;
 328
 329         /* srh is at transport offset and seg_left is already decremented
 330          * but daddr is not yet updated with next segment
 331          */
 332
 333         hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
 334         addr = hdr->segments + hdr->segments_left;
 335
 336         hdr->segments_left++;
 337         from = *(__be32 *)hdr;
 338
 339         hdr->segments_left--;
 340         to = *(__be32 *)hdr;
 341
 342         /* update skb csum with diff resulting from seg_left decrement */
 343
 344         update_csum_diff4(skb, from, to);
 345
 346         /* compute csum diff between current and next segment and update */
 347
 348         update_csum_diff16(skb, (__be32 *)(&ipv6_hdr(skb)->daddr),
 349                            (__be32 *)addr);
 350 }
 351
 352 static int ipv6_srh_rcv(struct sk_buff *skb)
 353 {
 354         struct inet6_skb_parm *opt = IP6CB(skb);
 355         struct net *net = dev_net(skb->dev);
 356         struct ipv6_sr_hdr *hdr;
 357         struct inet6_dev *idev;
 358         struct in6_addr *addr;
 359         int accept_seg6;
 360
 361         hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
 362
 363         idev = __in6_dev_get(skb->dev);
 364
 365         accept_seg6 = net->ipv6.devconf_all->seg6_enabled;
 366         if (accept_seg6 > idev->cnf.seg6_enabled)
 367                 accept_seg6 = idev->cnf.seg6_enabled;
 368
 369         if (!accept_seg6) {
 370                 kfree_skb(skb);
 371                 return -1;
 372         }
 373
 374 #ifdef CONFIG_IPV6_SEG6_HMAC
 375         if (!seg6_hmac_validate_skb(skb)) {
 376                 kfree_skb(skb);
 377                 return -1;
 378         }
 379 #endif
 380
 381 looped_back:
 382         if (hdr->segments_left == 0) {
 383                 if (hdr->nexthdr == NEXTHDR_IPV6) {
 384                         int offset = (hdr->hdrlen + 1) << 3;
 385
 386                         skb_postpull_rcsum(skb, skb_network_header(skb),
 387                                            skb_network_header_len(skb));
 388
 389                         if (!pskb_pull(skb, offset)) {
 390                                 kfree_skb(skb);
 391                                 return -1;
 392                         }
 393                         skb_postpull_rcsum(skb, skb_transport_header(skb),
 394                                            offset);
 395
 396                         skb_reset_network_header(skb);
 397                         skb_reset_transport_header(skb);
 398                         skb->encapsulation = 0;
 399
 400                         __skb_tunnel_rx(skb, skb->dev, net);
 401
 402                         netif_rx(skb);
 403                         return -1;
 404                 }
 405
 406                 opt->srcrt = skb_network_header_len(skb);
 407                 opt->lastopt = opt->srcrt;
 408                 skb->transport_header += (hdr->hdrlen + 1) << 3;
 409                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
 410
 411                 return 1;
 412         }
 413
 414         if (hdr->segments_left >= (hdr->hdrlen >> 1)) {
 415                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 416                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 417                                   ((&hdr->segments_left) -
 418                                    skb_network_header(skb)));
 419                 return -1;
 420         }
 421
 422         if (skb_cloned(skb)) {
 423                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
 424                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 425                                         IPSTATS_MIB_OUTDISCARDS);
 426                         kfree_skb(skb);
 427                         return -1;
 428                 }
 429         }
 430
 431         hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
 432
 433         hdr->segments_left--;
 434         addr = hdr->segments + hdr->segments_left;
 435
 436         skb_push(skb, sizeof(struct ipv6hdr));
 437
 438         if (skb->ip_summed == CHECKSUM_COMPLETE)
 439                 seg6_update_csum(skb);
 440
 441         ipv6_hdr(skb)->daddr = *addr;
 442
 443         skb_dst_drop(skb);
 444
 445         ip6_route_input(skb);
 446
 447         if (skb_dst(skb)->error) {
 448                 dst_input(skb);
 449                 return -1;
 450         }
 451
 452         if (skb_dst(skb)->dev->flags & IFF_LOOPBACK) {
 453                 if (ipv6_hdr(skb)->hop_limit <= 1) {
 454                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 455                         icmpv6_send(skb, ICMPV6_TIME_EXCEED,
 456                                     ICMPV6_EXC_HOPLIMIT, 0);
 457                         kfree_skb(skb);
 458                         return -1;
 459                 }
 460                 ipv6_hdr(skb)->hop_limit--;
 461
 462                 skb_pull(skb, sizeof(struct ipv6hdr));
 463                 goto looped_back;
 464         }
 465
 466         dst_input(skb);
 467
 468         return -1;
 469 }
 470
 471 /********************************
 472   Routing header.
 473  ********************************/
 474
 475 /* called with rcu_read_lock() */
 476 static int ipv6_rthdr_rcv(struct sk_buff *skb)
 477 {
 478         struct inet6_dev *idev = __in6_dev_get(skb->dev);
 479         struct inet6_skb_parm *opt = IP6CB(skb);
 480         struct in6_addr *addr = NULL;
 481         struct in6_addr daddr;
 482         int n, i;
 483         struct ipv6_rt_hdr *hdr;
 484         struct rt0_hdr *rthdr;
 485         struct net *net = dev_net(skb->dev);
 486         int accept_source_route = net->ipv6.devconf_all->accept_source_route;
 487
 488         idev = __in6_dev_get(skb->dev);
 489         if (idev && accept_source_route > idev->cnf.accept_source_route)
 490                 accept_source_route = idev->cnf.accept_source_route;
 491
 492         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 493             !pskb_may_pull(skb, (skb_transport_offset(skb) +
 494                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 495                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 496                 kfree_skb(skb);
 497                 return -1;
 498         }
 499
 500         hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 501
 502         if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ||
 503             skb->pkt_type != PACKET_HOST) {
 504                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 505                 kfree_skb(skb);
 506                 return -1;
 507         }
 508
 509         /* segment routing */
 510         if (hdr->type == IPV6_SRCRT_TYPE_4)
 511                 return ipv6_srh_rcv(skb);
 512
 513 looped_back:
 514         if (hdr->segments_left == 0) {
 515                 switch (hdr->type) {
 516 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 517                 case IPV6_SRCRT_TYPE_2:
 518                         /* Silently discard type 2 header unless it was
 519                          * processed by own
 520                          */
 521                         if (!addr) {
 522                                 __IP6_INC_STATS(net, idev,
 523                                                 IPSTATS_MIB_INADDRERRORS);
 524                                 kfree_skb(skb);
 525                                 return -1;
 526                         }
 527                         break;
 528 #endif
 529                 default:
 530                         break;
 531                 }
 532
 533                 opt->lastopt = opt->srcrt = skb_network_header_len(skb);
 534                 skb->transport_header += (hdr->hdrlen + 1) << 3;
 535                 opt->dst0 = opt->dst1;
 536                 opt->dst1 = 0;
 537                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
 538                 return 1;
 539         }
 540
 541         switch (hdr->type) {
 542 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 543         case IPV6_SRCRT_TYPE_2:
 544                 if (accept_source_route < 0)
 545                         goto unknown_rh;
 546                 /* Silently discard invalid RTH type 2 */
 547                 if (hdr->hdrlen != 2 || hdr->segments_left != 1) {
 548                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 549                         kfree_skb(skb);
 550                         return -1;
 551                 }
 552                 break;
 553 #endif
 554         default:
 555                 goto unknown_rh;
 556         }
 557
 558         /*
 559          *      This is the routing header forwarding algorithm from
 560          *      RFC 2460, page 16.
 561          */
 562
 563         n = hdr->hdrlen >> 1;
 564
 565         if (hdr->segments_left > n) {
 566                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 567                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 568                                   ((&hdr->segments_left) -
 569                                    skb_network_header(skb)));
 570                 return -1;
 571         }
 572
 573         /* We are about to mangle packet header. Be careful!
 574            Do not damage packets queued somewhere.
 575          */
 576         if (skb_cloned(skb)) {
 577                 /* the copy is a forwarded packet */
 578                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
 579                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 580                                         IPSTATS_MIB_OUTDISCARDS);
 581                         kfree_skb(skb);
 582                         return -1;
 583                 }
 584                 hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 585         }
 586
 587         if (skb->ip_summed == CHECKSUM_COMPLETE)
 588                 skb->ip_summed = CHECKSUM_NONE;
 589
 590         i = n - --hdr->segments_left;
 591
 592         rthdr = (struct rt0_hdr *) hdr;
 593         addr = rthdr->addr;
 594         addr += i - 1;
 595
 596         switch (hdr->type) {
 597 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 598         case IPV6_SRCRT_TYPE_2:
 599                 if (xfrm6_input_addr(skb, (xfrm_address_t *)addr,
 600                                      (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 601                                      IPPROTO_ROUTING) < 0) {
 602                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 603                         kfree_skb(skb);
 604                         return -1;
 605                 }
 606                 if (!ipv6_chk_home_addr(dev_net(skb_dst(skb)->dev), addr)) {
 607                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 608                         kfree_skb(skb);
 609                         return -1;
 610                 }
 611                 break;
 612 #endif
 613         default:
 614                 break;
 615         }
 616
 617         if (ipv6_addr_is_multicast(addr)) {
 618                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 619                 kfree_skb(skb);
 620                 return -1;
 621         }
 622
 623         daddr = *addr;
 624         *addr = ipv6_hdr(skb)->daddr;
 625         ipv6_hdr(skb)->daddr = daddr;
 626
 627         skb_dst_drop(skb);
 628         ip6_route_input(skb);
 629         if (skb_dst(skb)->error) {
 630                 skb_push(skb, skb->data - skb_network_header(skb));
 631                 dst_input(skb);
 632                 return -1;
 633         }
 634
 635         if (skb_dst(skb)->dev->flags&IFF_LOOPBACK) {
 636                 if (ipv6_hdr(skb)->hop_limit <= 1) {
 637                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 638                         icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
 639                                     0);
 640                         kfree_skb(skb);
 641                         return -1;
 642                 }
 643                 ipv6_hdr(skb)->hop_limit--;
 644                 goto looped_back;
 645         }
 646
 647         skb_push(skb, skb->data - skb_network_header(skb));
 648         dst_input(skb);
 649         return -1;
 650
 651 unknown_rh:
 652         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 653         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 654                           (&hdr->type) - skb_network_header(skb));
 655         return -1;
 656 }
 657
 658 static const struct inet6_protocol rthdr_protocol = {
 659         .handler        =       ipv6_rthdr_rcv,
 660         .flags          =       INET6_PROTO_NOPOLICY,
 661 };
 662
 663 static const struct inet6_protocol destopt_protocol = {
 664         .handler        =       ipv6_destopt_rcv,
 665         .flags          =       INET6_PROTO_NOPOLICY,
 666 };
 667
 668 static const struct inet6_protocol nodata_protocol = {
 669         .handler        =       dst_discard,
 670         .flags          =       INET6_PROTO_NOPOLICY,
 671 };
 672
 673 int __init ipv6_exthdrs_init(void)
 674 {
 675         int ret;
 676
 677         ret = inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 678         if (ret)
 679                 goto out;
 680
 681         ret = inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 682         if (ret)
 683                 goto out_rthdr;
 684
 685         ret = inet6_add_protocol(&nodata_protocol, IPPROTO_NONE);
 686         if (ret)
 687                 goto out_destopt;
 688
 689 out:
 690         return ret;
 691 out_destopt:
 692         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 693 out_rthdr:
 694         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 695         goto out;
 696 };
 697
 698 void ipv6_exthdrs_exit(void)
 699 {
 700         inet6_del_protocol(&nodata_protocol, IPPROTO_NONE);
 701         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 702         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 703 }
 704
 705 /**********************************
 706   Hop-by-hop options.
 707  **********************************/
 708
 709 /*
 710  * Note: we cannot rely on skb_dst(skb) before we assign it in ip6_route_input().
 711  */
 712 static inline struct inet6_dev *ipv6_skb_idev(struct sk_buff *skb)
 713 {
 714         return skb_dst(skb) ? ip6_dst_idev(skb_dst(skb)) : __in6_dev_get(skb->dev);
 715 }
 716
 717 static inline struct net *ipv6_skb_net(struct sk_buff *skb)
 718 {
 719         return skb_dst(skb) ? dev_net(skb_dst(skb)->dev) : dev_net(skb->dev);
 720 }
 721
 722 /* Router Alert as of RFC 2711 */
 723
 724 static bool ipv6_hop_ra(struct sk_buff *skb, int optoff)
 725 {
 726         const unsigned char *nh = skb_network_header(skb);
 727
 728         if (nh[optoff + 1] == 2) {
 729                 IP6CB(skb)->flags |= IP6SKB_ROUTERALERT;
 730                 memcpy(&IP6CB(skb)->ra, nh + optoff + 2, sizeof(IP6CB(skb)->ra));
 731                 return true;
 732         }
 733         net_dbg_ratelimited("ipv6_hop_ra: wrong RA length %d\n",
 734                             nh[optoff + 1]);
 735         kfree_skb(skb);
 736         return false;
 737 }
 738
 739 /* Jumbo payload */
 740
 741 static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
 742 {
 743         const unsigned char *nh = skb_network_header(skb);
 744         struct inet6_dev *idev = __in6_dev_get_safely(skb->dev);
 745         struct net *net = ipv6_skb_net(skb);
 746         u32 pkt_len;
 747
 748         if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
 749                 net_dbg_ratelimited("ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
 750                                     nh[optoff+1]);
 751                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 752                 goto drop;
 753         }
 754
 755         pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
 756         if (pkt_len <= IPV6_MAXPLEN) {
 757                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 758                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2);
 759                 return false;
 760         }
 761         if (ipv6_hdr(skb)->payload_len) {
 762                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 763                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff);
 764                 return false;
 765         }
 766
 767         if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
 768                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INTRUNCATEDPKTS);
 769                 goto drop;
 770         }
 771
 772         if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 773                 goto drop;
 774
 775         IP6CB(skb)->flags |= IP6SKB_JUMBOGRAM;
 776         return true;
 777
 778 drop:
 779         kfree_skb(skb);
 780         return false;
 781 }
 782
 783 /* CALIPSO RFC 5570 */
 784
 785 static bool ipv6_hop_calipso(struct sk_buff *skb, int optoff)
 786 {
 787         const unsigned char *nh = skb_network_header(skb);
 788
 789         if (nh[optoff + 1] < 8)
 790                 goto drop;
 791
 792         if (nh[optoff + 6] * 4 + 8 > nh[optoff + 1])
 793                 goto drop;
 794
 795         if (!calipso_validate(skb, nh + optoff))
 796                 goto drop;
 797
 798         return true;
 799
 800 drop:
 801         kfree_skb(skb);
 802         return false;
 803 }
 804
 805 static const struct tlvtype_proc tlvprochopopt_lst[] = {
 806         {
 807                 .type   = IPV6_TLV_ROUTERALERT,
 808                 .func   = ipv6_hop_ra,
 809         },
 810         {
 811                 .type   = IPV6_TLV_JUMBO,
 812                 .func   = ipv6_hop_jumbo,
 813         },
 814         {
 815                 .type   = IPV6_TLV_CALIPSO,
 816                 .func   = ipv6_hop_calipso,
 817         },
 818         { -1, }
 819 };
 820
 821 int ipv6_parse_hopopts(struct sk_buff *skb)
 822 {
 823         struct inet6_skb_parm *opt = IP6CB(skb);
 824         struct net *net = dev_net(skb->dev);
 825         int extlen;
 826
 827         /*
 828          * skb_network_header(skb) is equal to skb->data, and
 829          * skb_network_header_len(skb) is always equal to
 830          * sizeof(struct ipv6hdr) by definition of
 831          * hop-by-hop options.
 832          */
 833         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
 834             !pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
 835                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 836 fail_and_free:
 837                 kfree_skb(skb);
 838                 return -1;
 839         }
 840
 841         extlen = (skb_transport_header(skb)[1] + 1) << 3;
 842         if (extlen > net->ipv6.sysctl.max_hbh_opts_len)
 843                 goto fail_and_free;
 844
 845         opt->flags |= IP6SKB_HOPBYHOP;
 846         if (ip6_parse_tlv(tlvprochopopt_lst, skb,
 847                           init_net.ipv6.sysctl.max_hbh_opts_cnt)) {
 848                 skb->transport_header += extlen;
 849                 opt = IP6CB(skb);
 850                 opt->nhoff = sizeof(struct ipv6hdr);
 851                 return 1;
 852         }
 853         return -1;
 854 }
 855
 856 /*
 857  *      Creating outbound headers.
 858  *
 859  *      "build" functions work when skb is filled from head to tail (datagram)
 860  *      "push"  functions work when headers are added from tail to head (tcp)
 861  *
 862  *      In both cases we assume, that caller reserved enough room
 863  *      for headers.
 864  */
 865
 866 static void ipv6_push_rthdr0(struct sk_buff *skb, u8 *proto,
 867                              struct ipv6_rt_hdr *opt,
 868                              struct in6_addr **addr_p, struct in6_addr *saddr)
 869 {
 870         struct rt0_hdr *phdr, *ihdr;
 871         int hops;
 872
 873         ihdr = (struct rt0_hdr *) opt;
 874
 875         phdr = skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
 876         memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
 877
 878         hops = ihdr->rt_hdr.hdrlen >> 1;
 879
 880         if (hops > 1)
 881                 memcpy(phdr->addr, ihdr->addr + 1,
 882                        (hops - 1) * sizeof(struct in6_addr));
 883
 884         phdr->addr[hops - 1] = **addr_p;
 885         *addr_p = ihdr->addr;
 886
 887         phdr->rt_hdr.nexthdr = *proto;
 888         *proto = NEXTHDR_ROUTING;
 889 }
 890
 891 static void ipv6_push_rthdr4(struct sk_buff *skb, u8 *proto,
 892                              struct ipv6_rt_hdr *opt,
 893                              struct in6_addr **addr_p, struct in6_addr *saddr)
 894 {
 895         struct ipv6_sr_hdr *sr_phdr, *sr_ihdr;
 896         int plen, hops;
 897
 898         sr_ihdr = (struct ipv6_sr_hdr *)opt;
 899         plen = (sr_ihdr->hdrlen + 1) << 3;
 900
 901         sr_phdr = skb_push(skb, plen);
 902         memcpy(sr_phdr, sr_ihdr, sizeof(struct ipv6_sr_hdr));
 903
 904         hops = sr_ihdr->first_segment + 1;
 905         memcpy(sr_phdr->segments + 1, sr_ihdr->segments + 1,
 906                (hops - 1) * sizeof(struct in6_addr));
 907
 908         sr_phdr->segments[0] = **addr_p;
 909         *addr_p = &sr_ihdr->segments[sr_ihdr->segments_left];
 910
 911         if (sr_ihdr->hdrlen > hops * 2) {
 912                 int tlvs_offset, tlvs_length;
 913
 914                 tlvs_offset = (1 + hops * 2) << 3;
 915                 tlvs_length = (sr_ihdr->hdrlen - hops * 2) << 3;
 916                 memcpy((char *)sr_phdr + tlvs_offset,
 917                        (char *)sr_ihdr + tlvs_offset, tlvs_length);
 918         }
 919
 920 #ifdef CONFIG_IPV6_SEG6_HMAC
 921         if (sr_has_hmac(sr_phdr)) {
 922                 struct net *net = NULL;
 923
 924                 if (skb->dev)
 925                         net = dev_net(skb->dev);
 926                 else if (skb->sk)
 927                         net = sock_net(skb->sk);
 928
 929                 WARN_ON(!net);
 930
 931                 if (net)
 932                         seg6_push_hmac(net, saddr, sr_phdr);
 933         }
 934 #endif
 935
 936         sr_phdr->nexthdr = *proto;
 937         *proto = NEXTHDR_ROUTING;
 938 }
 939
 940 static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
 941                             struct ipv6_rt_hdr *opt,
 942                             struct in6_addr **addr_p, struct in6_addr *saddr)
 943 {
 944         switch (opt->type) {
 945         case IPV6_SRCRT_TYPE_0:
 946         case IPV6_SRCRT_STRICT:
 947         case IPV6_SRCRT_TYPE_2:
 948                 ipv6_push_rthdr0(skb, proto, opt, addr_p, saddr);
 949                 break;
 950         case IPV6_SRCRT_TYPE_4:
 951                 ipv6_push_rthdr4(skb, proto, opt, addr_p, saddr);
 952                 break;
 953         default:
 954                 break;
 955         }
 956 }
 957
 958 static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
 959 {
 960         struct ipv6_opt_hdr *h = skb_push(skb, ipv6_optlen(opt));
 961
 962         memcpy(h, opt, ipv6_optlen(opt));
 963         h->nexthdr = *proto;
 964         *proto = type;
 965 }
 966
 967 void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
 968                           u8 *proto,
 969                           struct in6_addr **daddr, struct in6_addr *saddr)
 970 {
 971         if (opt->srcrt) {
 972                 ipv6_push_rthdr(skb, proto, opt->srcrt, daddr, saddr);
 973                 /*
 974                  * IPV6_RTHDRDSTOPTS is ignored
 975                  * unless IPV6_RTHDR is set (RFC3542).
 976                  */
 977                 if (opt->dst0opt)
 978                         ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
 979         }
 980         if (opt->hopopt)
 981                 ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
 982 }
 983
 984 void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
 985 {
 986         if (opt->dst1opt)
 987                 ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
 988 }
 989 EXPORT_SYMBOL(ipv6_push_frag_opts);
 990
 991 struct ipv6_txoptions *
 992 ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
 993 {
 994         struct ipv6_txoptions *opt2;
 995
 996         opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
 997         if (opt2) {
 998                 long dif = (char *)opt2 - (char *)opt;
 999                 memcpy(opt2, opt, opt->tot_len);
1000                 if (opt2->hopopt)
1001                         *((char **)&opt2->hopopt) += dif;
1002                 if (opt2->dst0opt)
1003                         *((char **)&opt2->dst0opt) += dif;
1004                 if (opt2->dst1opt)
1005                         *((char **)&opt2->dst1opt) += dif;
1006                 if (opt2->srcrt)
1007                         *((char **)&opt2->srcrt) += dif;
1008                 refcount_set(&opt2->refcnt, 1);
1009         }
1010         return opt2;
1011 }
1012 EXPORT_SYMBOL_GPL(ipv6_dup_options);
1013
1014 static void ipv6_renew_option(int renewtype,
1015                               struct ipv6_opt_hdr **dest,
1016                               struct ipv6_opt_hdr *old,
1017                               struct ipv6_opt_hdr *new,
1018                               int newtype, char **p)
1019 {
1020         struct ipv6_opt_hdr *src;
1021
1022         src = (renewtype == newtype ? new : old);
1023         if (!src)
1024                 return;
1025
1026         memcpy(*p, src, ipv6_optlen(src));
1027         *dest = (struct ipv6_opt_hdr *)*p;
1028         *p += CMSG_ALIGN(ipv6_optlen(*dest));
1029 }
1030
1031 /**
1032  * ipv6_renew_options - replace a specific ext hdr with a new one.
1033  *
1034  * @sk: sock from which to allocate memory
1035  * @opt: original options
1036  * @newtype: option type to replace in @opt
1037  * @newopt: new option of type @newtype to replace (user-mem)
1038  * @newoptlen: length of @newopt
1039  *
1040  * Returns a new set of options which is a copy of @opt with the
1041  * option type @newtype replaced with @newopt.
1042  *
1043  * @opt may be NULL, in which case a new set of options is returned
1044  * containing just @newopt.
1045  *
1046  * @newopt may be NULL, in which case the specified option type is
1047  * not copied into the new set of options.
1048  *
1049  * The new set of options is allocated from the socket option memory
1050  * buffer of @sk.
1051  */
1052 struct ipv6_txoptions *
1053 ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
1054                    int newtype, struct ipv6_opt_hdr *newopt)
1055 {
1056         int tot_len = 0;
1057         char *p;
1058         struct ipv6_txoptions *opt2;
1059
1060         if (opt) {
1061                 if (newtype != IPV6_HOPOPTS && opt->hopopt)
1062                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
1063                 if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
1064                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
1065                 if (newtype != IPV6_RTHDR && opt->srcrt)
1066                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
1067                 if (newtype != IPV6_DSTOPTS && opt->dst1opt)
1068                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
1069         }
1070
1071         if (newopt)
1072                 tot_len += CMSG_ALIGN(ipv6_optlen(newopt));
1073
1074         if (!tot_len)
1075                 return NULL;
1076
1077         tot_len += sizeof(*opt2);
1078         opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
1079         if (!opt2)
1080                 return ERR_PTR(-ENOBUFS);
1081
1082         memset(opt2, 0, tot_len);
1083         refcount_set(&opt2->refcnt, 1);
1084         opt2->tot_len = tot_len;
1085         p = (char *)(opt2 + 1);
1086
1087         ipv6_renew_option(IPV6_HOPOPTS, &opt2->hopopt,
1088                           (opt ? opt->hopopt : NULL),
1089                           newopt, newtype, &p);
1090         ipv6_renew_option(IPV6_RTHDRDSTOPTS, &opt2->dst0opt,
1091                           (opt ? opt->dst0opt : NULL),
1092                           newopt, newtype, &p);
1093         ipv6_renew_option(IPV6_RTHDR,
1094                           (struct ipv6_opt_hdr **)&opt2->srcrt,
1095                           (opt ? (struct ipv6_opt_hdr *)opt->srcrt : NULL),
1096                           newopt, newtype, &p);
1097         ipv6_renew_option(IPV6_DSTOPTS, &opt2->dst1opt,
1098                           (opt ? opt->dst1opt : NULL),
1099                           newopt, newtype, &p);
1100
1101         opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
1102                           (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
1103                           (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
1104         opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
1105
1106         return opt2;
1107 }
1108
1109 struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space,
1110                                           struct ipv6_txoptions *opt)
1111 {
1112         /*
1113          * ignore the dest before srcrt unless srcrt is being included.
1114          * --yoshfuji
1115          */
1116         if (opt && opt->dst0opt && !opt->srcrt) {
1117                 if (opt_space != opt) {
1118                         memcpy(opt_space, opt, sizeof(*opt_space));
1119                         opt = opt_space;
1120                 }
1121                 opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
1122                 opt->dst0opt = NULL;
1123         }
1124
1125         return opt;
1126 }
1127 EXPORT_SYMBOL_GPL(ipv6_fixup_options);
1128
1129 /**
1130  * fl6_update_dst - update flowi destination address with info given
1131  *                  by srcrt option, if any.
1132  *
1133  * @fl6: flowi6 for which daddr is to be updated
1134  * @opt: struct ipv6_txoptions in which to look for srcrt opt
1135  * @orig: copy of original daddr address if modified
1136  *
1137  * Returns NULL if no txoptions or no srcrt, otherwise returns orig
1138  * and initial value of fl6->daddr set in orig
1139  */
1140 struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
1141                                 const struct ipv6_txoptions *opt,
1142                                 struct in6_addr *orig)
1143 {
1144         if (!opt || !opt->srcrt)
1145                 return NULL;
1146
1147         *orig = fl6->daddr;
1148
1149         switch (opt->srcrt->type) {
1150         case IPV6_SRCRT_TYPE_0:
1151         case IPV6_SRCRT_STRICT:
1152         case IPV6_SRCRT_TYPE_2:
1153                 fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr;
1154                 break;
1155         case IPV6_SRCRT_TYPE_4:
1156         {
1157                 struct ipv6_sr_hdr *srh = (struct ipv6_sr_hdr *)opt->srcrt;
1158
1159                 fl6->daddr = srh->segments[srh->segments_left];
1160                 break;
1161         }
1162         default:
1163                 return NULL;
1164         }
1165
1166         return orig;
1167 }
1168 EXPORT_SYMBOL_GPL(fl6_update_dst);