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 #include <net/rpl.h>
  52 #include <linux/ioam6.h>
  53 #include <net/ioam6.h>
  54 #include <net/dst_metadata.h>
  55
  56 #include <linux/uaccess.h>
  57
  58 /*********************
  59   Generic functions
  60  *********************/
  61
  62 /* An unknown option is detected, decide what to do */
  63
  64 static bool ip6_tlvopt_unknown(struct sk_buff *skb, int optoff,
  65                                bool disallow_unknowns)
  66 {
  67         if (disallow_unknowns) {
  68                 /* If unknown TLVs are disallowed by configuration
  69                  * then always silently drop packet. Note this also
  70                  * means no ICMP parameter problem is sent which
  71                  * could be a good property to mitigate a reflection DOS
  72                  * attack.
  73                  */
  74
  75                 goto drop;
  76         }
  77
  78         switch ((skb_network_header(skb)[optoff] & 0xC0) >> 6) {
  79         case 0: /* ignore */
  80                 return true;
  81
  82         case 1: /* drop packet */
  83                 break;
  84
  85         case 3: /* Send ICMP if not a multicast address and drop packet */
  86                 /* Actually, it is redundant check. icmp_send
  87                    will recheck in any case.
  88                  */
  89                 if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr))
  90                         break;
  91                 fallthrough;
  92         case 2: /* send ICMP PARM PROB regardless and drop packet */
  93                 icmpv6_param_prob_reason(skb, ICMPV6_UNK_OPTION, optoff,
  94                                          SKB_DROP_REASON_UNHANDLED_PROTO);
  95                 return false;
  96         }
  97
  98 drop:
  99         kfree_skb_reason(skb, SKB_DROP_REASON_UNHANDLED_PROTO);
 100         return false;
 101 }
 102
 103 static bool ipv6_hop_ra(struct sk_buff *skb, int optoff);
 104 static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff);
 105 static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff);
 106 static bool ipv6_hop_calipso(struct sk_buff *skb, int optoff);
 107 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 108 static bool ipv6_dest_hao(struct sk_buff *skb, int optoff);
 109 #endif
 110
 111 /* Parse tlv encoded option header (hop-by-hop or destination) */
 112
 113 static bool ip6_parse_tlv(bool hopbyhop,
 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         bool disallow_unknowns = false;
 121         int tlv_count = 0;
 122         int padlen = 0;
 123
 124         if (unlikely(max_count < 0)) {
 125                 disallow_unknowns = true;
 126                 max_count = -max_count;
 127         }
 128
 129         if (skb_transport_offset(skb) + len > skb_headlen(skb))
 130                 goto bad;
 131
 132         off += 2;
 133         len -= 2;
 134
 135         while (len > 0) {
 136                 int optlen, i;
 137
 138                 if (nh[off] == IPV6_TLV_PAD1) {
 139                         padlen++;
 140                         if (padlen > 7)
 141                                 goto bad;
 142                         off++;
 143                         len--;
 144                         continue;
 145                 }
 146                 if (len < 2)
 147                         goto bad;
 148                 optlen = nh[off + 1] + 2;
 149                 if (optlen > len)
 150                         goto bad;
 151
 152                 if (nh[off] == IPV6_TLV_PADN) {
 153                         /* RFC 2460 states that the purpose of PadN is
 154                          * to align the containing header to multiples
 155                          * of 8. 7 is therefore the highest valid value.
 156                          * See also RFC 4942, Section 2.1.9.5.
 157                          */
 158                         padlen += optlen;
 159                         if (padlen > 7)
 160                                 goto bad;
 161                         /* RFC 4942 recommends receiving hosts to
 162                          * actively check PadN payload to contain
 163                          * only zeroes.
 164                          */
 165                         for (i = 2; i < optlen; i++) {
 166                                 if (nh[off + i] != 0)
 167                                         goto bad;
 168                         }
 169                 } else {
 170                         tlv_count++;
 171                         if (tlv_count > max_count)
 172                                 goto bad;
 173
 174                         if (hopbyhop) {
 175                                 switch (nh[off]) {
 176                                 case IPV6_TLV_ROUTERALERT:
 177                                         if (!ipv6_hop_ra(skb, off))
 178                                                 return false;
 179                                         break;
 180                                 case IPV6_TLV_IOAM:
 181                                         if (!ipv6_hop_ioam(skb, off))
 182                                                 return false;
 183
 184                                         nh = skb_network_header(skb);
 185                                         break;
 186                                 case IPV6_TLV_JUMBO:
 187                                         if (!ipv6_hop_jumbo(skb, off))
 188                                                 return false;
 189                                         break;
 190                                 case IPV6_TLV_CALIPSO:
 191                                         if (!ipv6_hop_calipso(skb, off))
 192                                                 return false;
 193                                         break;
 194                                 default:
 195                                         if (!ip6_tlvopt_unknown(skb, off,
 196                                                                 disallow_unknowns))
 197                                                 return false;
 198                                         break;
 199                                 }
 200                         } else {
 201                                 switch (nh[off]) {
 202 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 203                                 case IPV6_TLV_HAO:
 204                                         if (!ipv6_dest_hao(skb, off))
 205                                                 return false;
 206                                         break;
 207 #endif
 208                                 default:
 209                                         if (!ip6_tlvopt_unknown(skb, off,
 210                                                                 disallow_unknowns))
 211                                                 return false;
 212                                         break;
 213                                 }
 214                         }
 215                         padlen = 0;
 216                 }
 217                 off += optlen;
 218                 len -= optlen;
 219         }
 220
 221         if (len == 0)
 222                 return true;
 223 bad:
 224         kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR);
 225         return false;
 226 }
 227
 228 /*****************************
 229   Destination options header.
 230  *****************************/
 231
 232 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 233 static bool ipv6_dest_hao(struct sk_buff *skb, int optoff)
 234 {
 235         struct ipv6_destopt_hao *hao;
 236         struct inet6_skb_parm *opt = IP6CB(skb);
 237         struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 238         SKB_DR(reason);
 239         int ret;
 240
 241         if (opt->dsthao) {
 242                 net_dbg_ratelimited("hao duplicated\n");
 243                 goto discard;
 244         }
 245         opt->dsthao = opt->dst1;
 246         opt->dst1 = 0;
 247
 248         hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) + optoff);
 249
 250         if (hao->length != 16) {
 251                 net_dbg_ratelimited("hao invalid option length = %d\n",
 252                                     hao->length);
 253                 SKB_DR_SET(reason, IP_INHDR);
 254                 goto discard;
 255         }
 256
 257         if (!(ipv6_addr_type(&hao->addr) & IPV6_ADDR_UNICAST)) {
 258                 net_dbg_ratelimited("hao is not an unicast addr: %pI6\n",
 259                                     &hao->addr);
 260                 SKB_DR_SET(reason, INVALID_PROTO);
 261                 goto discard;
 262         }
 263
 264         ret = xfrm6_input_addr(skb, (xfrm_address_t *)&ipv6h->daddr,
 265                                (xfrm_address_t *)&hao->addr, IPPROTO_DSTOPTS);
 266         if (unlikely(ret < 0)) {
 267                 SKB_DR_SET(reason, XFRM_POLICY);
 268                 goto discard;
 269         }
 270
 271         if (skb_cloned(skb)) {
 272                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 273                         goto discard;
 274
 275                 /* update all variable using below by copied skbuff */
 276                 hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) +
 277                                                   optoff);
 278                 ipv6h = ipv6_hdr(skb);
 279         }
 280
 281         if (skb->ip_summed == CHECKSUM_COMPLETE)
 282                 skb->ip_summed = CHECKSUM_NONE;
 283
 284         swap(ipv6h->saddr, hao->addr);
 285
 286         if (skb->tstamp == 0)
 287                 __net_timestamp(skb);
 288
 289         return true;
 290
 291  discard:
 292         kfree_skb_reason(skb, reason);
 293         return false;
 294 }
 295 #endif
 296
 297 static int ipv6_destopt_rcv(struct sk_buff *skb)
 298 {
 299         struct inet6_dev *idev = __in6_dev_get(skb->dev);
 300         struct inet6_skb_parm *opt = IP6CB(skb);
 301 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 302         __u16 dstbuf;
 303 #endif
 304         struct dst_entry *dst = skb_dst(skb);
 305         struct net *net = dev_net(skb->dev);
 306         int extlen;
 307
 308         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 309             !pskb_may_pull(skb, (skb_transport_offset(skb) +
 310                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 311                 __IP6_INC_STATS(dev_net(dst->dev), idev,
 312                                 IPSTATS_MIB_INHDRERRORS);
 313 fail_and_free:
 314                 kfree_skb(skb);
 315                 return -1;
 316         }
 317
 318         extlen = (skb_transport_header(skb)[1] + 1) << 3;
 319         if (extlen > net->ipv6.sysctl.max_dst_opts_len)
 320                 goto fail_and_free;
 321
 322         opt->lastopt = opt->dst1 = skb_network_header_len(skb);
 323 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 324         dstbuf = opt->dst1;
 325 #endif
 326
 327         if (ip6_parse_tlv(false, skb, net->ipv6.sysctl.max_dst_opts_cnt)) {
 328                 skb->transport_header += extlen;
 329                 opt = IP6CB(skb);
 330 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 331                 opt->nhoff = dstbuf;
 332 #else
 333                 opt->nhoff = opt->dst1;
 334 #endif
 335                 return 1;
 336         }
 337
 338         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 339         return -1;
 340 }
 341
 342 static void seg6_update_csum(struct sk_buff *skb)
 343 {
 344         struct ipv6_sr_hdr *hdr;
 345         struct in6_addr *addr;
 346         __be32 from, to;
 347
 348         /* srh is at transport offset and seg_left is already decremented
 349          * but daddr is not yet updated with next segment
 350          */
 351
 352         hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
 353         addr = hdr->segments + hdr->segments_left;
 354
 355         hdr->segments_left++;
 356         from = *(__be32 *)hdr;
 357
 358         hdr->segments_left--;
 359         to = *(__be32 *)hdr;
 360
 361         /* update skb csum with diff resulting from seg_left decrement */
 362
 363         update_csum_diff4(skb, from, to);
 364
 365         /* compute csum diff between current and next segment and update */
 366
 367         update_csum_diff16(skb, (__be32 *)(&ipv6_hdr(skb)->daddr),
 368                            (__be32 *)addr);
 369 }
 370
 371 static int ipv6_srh_rcv(struct sk_buff *skb)
 372 {
 373         struct inet6_skb_parm *opt = IP6CB(skb);
 374         struct net *net = dev_net(skb->dev);
 375         struct ipv6_sr_hdr *hdr;
 376         struct inet6_dev *idev;
 377         struct in6_addr *addr;
 378         int accept_seg6;
 379
 380         hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
 381
 382         idev = __in6_dev_get(skb->dev);
 383
 384         accept_seg6 = net->ipv6.devconf_all->seg6_enabled;
 385         if (accept_seg6 > idev->cnf.seg6_enabled)
 386                 accept_seg6 = idev->cnf.seg6_enabled;
 387
 388         if (!accept_seg6) {
 389                 kfree_skb(skb);
 390                 return -1;
 391         }
 392
 393 #ifdef CONFIG_IPV6_SEG6_HMAC
 394         if (!seg6_hmac_validate_skb(skb)) {
 395                 kfree_skb(skb);
 396                 return -1;
 397         }
 398 #endif
 399
 400 looped_back:
 401         if (hdr->segments_left == 0) {
 402                 if (hdr->nexthdr == NEXTHDR_IPV6 || hdr->nexthdr == NEXTHDR_IPV4) {
 403                         int offset = (hdr->hdrlen + 1) << 3;
 404
 405                         skb_postpull_rcsum(skb, skb_network_header(skb),
 406                                            skb_network_header_len(skb));
 407
 408                         if (!pskb_pull(skb, offset)) {
 409                                 kfree_skb(skb);
 410                                 return -1;
 411                         }
 412                         skb_postpull_rcsum(skb, skb_transport_header(skb),
 413                                            offset);
 414
 415                         skb_reset_network_header(skb);
 416                         skb_reset_transport_header(skb);
 417                         skb->encapsulation = 0;
 418                         if (hdr->nexthdr == NEXTHDR_IPV4)
 419                                 skb->protocol = htons(ETH_P_IP);
 420                         __skb_tunnel_rx(skb, skb->dev, net);
 421
 422                         netif_rx(skb);
 423                         return -1;
 424                 }
 425
 426                 opt->srcrt = skb_network_header_len(skb);
 427                 opt->lastopt = opt->srcrt;
 428                 skb->transport_header += (hdr->hdrlen + 1) << 3;
 429                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
 430
 431                 return 1;
 432         }
 433
 434         if (hdr->segments_left >= (hdr->hdrlen >> 1)) {
 435                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 436                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 437                                   ((&hdr->segments_left) -
 438                                    skb_network_header(skb)));
 439                 return -1;
 440         }
 441
 442         if (skb_cloned(skb)) {
 443                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
 444                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 445                                         IPSTATS_MIB_OUTDISCARDS);
 446                         kfree_skb(skb);
 447                         return -1;
 448                 }
 449         }
 450
 451         hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
 452
 453         hdr->segments_left--;
 454         addr = hdr->segments + hdr->segments_left;
 455
 456         skb_push(skb, sizeof(struct ipv6hdr));
 457
 458         if (skb->ip_summed == CHECKSUM_COMPLETE)
 459                 seg6_update_csum(skb);
 460
 461         ipv6_hdr(skb)->daddr = *addr;
 462
 463         skb_dst_drop(skb);
 464
 465         ip6_route_input(skb);
 466
 467         if (skb_dst(skb)->error) {
 468                 dst_input(skb);
 469                 return -1;
 470         }
 471
 472         if (skb_dst(skb)->dev->flags & IFF_LOOPBACK) {
 473                 if (ipv6_hdr(skb)->hop_limit <= 1) {
 474                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 475                         icmpv6_send(skb, ICMPV6_TIME_EXCEED,
 476                                     ICMPV6_EXC_HOPLIMIT, 0);
 477                         kfree_skb(skb);
 478                         return -1;
 479                 }
 480                 ipv6_hdr(skb)->hop_limit--;
 481
 482                 skb_pull(skb, sizeof(struct ipv6hdr));
 483                 goto looped_back;
 484         }
 485
 486         dst_input(skb);
 487
 488         return -1;
 489 }
 490
 491 static int ipv6_rpl_srh_rcv(struct sk_buff *skb)
 492 {
 493         struct ipv6_rpl_sr_hdr *hdr, *ohdr, *chdr;
 494         struct inet6_skb_parm *opt = IP6CB(skb);
 495         struct net *net = dev_net(skb->dev);
 496         struct inet6_dev *idev;
 497         struct ipv6hdr *oldhdr;
 498         unsigned char *buf;
 499         int accept_rpl_seg;
 500         int i, err;
 501         u64 n = 0;
 502         u32 r;
 503
 504         idev = __in6_dev_get(skb->dev);
 505
 506         accept_rpl_seg = net->ipv6.devconf_all->rpl_seg_enabled;
 507         if (accept_rpl_seg > idev->cnf.rpl_seg_enabled)
 508                 accept_rpl_seg = idev->cnf.rpl_seg_enabled;
 509
 510         if (!accept_rpl_seg) {
 511                 kfree_skb(skb);
 512                 return -1;
 513         }
 514
 515 looped_back:
 516         hdr = (struct ipv6_rpl_sr_hdr *)skb_transport_header(skb);
 517
 518         if (hdr->segments_left == 0) {
 519                 if (hdr->nexthdr == NEXTHDR_IPV6) {
 520                         int offset = (hdr->hdrlen + 1) << 3;
 521
 522                         skb_postpull_rcsum(skb, skb_network_header(skb),
 523                                            skb_network_header_len(skb));
 524
 525                         if (!pskb_pull(skb, offset)) {
 526                                 kfree_skb(skb);
 527                                 return -1;
 528                         }
 529                         skb_postpull_rcsum(skb, skb_transport_header(skb),
 530                                            offset);
 531
 532                         skb_reset_network_header(skb);
 533                         skb_reset_transport_header(skb);
 534                         skb->encapsulation = 0;
 535
 536                         __skb_tunnel_rx(skb, skb->dev, net);
 537
 538                         netif_rx(skb);
 539                         return -1;
 540                 }
 541
 542                 opt->srcrt = skb_network_header_len(skb);
 543                 opt->lastopt = opt->srcrt;
 544                 skb->transport_header += (hdr->hdrlen + 1) << 3;
 545                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
 546
 547                 return 1;
 548         }
 549
 550         if (!pskb_may_pull(skb, sizeof(*hdr))) {
 551                 kfree_skb(skb);
 552                 return -1;
 553         }
 554
 555         n = (hdr->hdrlen << 3) - hdr->pad - (16 - hdr->cmpre);
 556         r = do_div(n, (16 - hdr->cmpri));
 557         /* checks if calculation was without remainder and n fits into
 558          * unsigned char which is segments_left field. Should not be
 559          * higher than that.
 560          */
 561         if (r || (n + 1) > 255) {
 562                 kfree_skb(skb);
 563                 return -1;
 564         }
 565
 566         if (hdr->segments_left > n + 1) {
 567                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 568                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 569                                   ((&hdr->segments_left) -
 570                                    skb_network_header(skb)));
 571                 return -1;
 572         }
 573
 574         if (!pskb_may_pull(skb, ipv6_rpl_srh_size(n, hdr->cmpri,
 575                                                   hdr->cmpre))) {
 576                 kfree_skb(skb);
 577                 return -1;
 578         }
 579
 580         hdr->segments_left--;
 581         i = n - hdr->segments_left;
 582
 583         buf = kcalloc(struct_size(hdr, segments.addr, n + 2), 2, GFP_ATOMIC);
 584         if (unlikely(!buf)) {
 585                 kfree_skb(skb);
 586                 return -1;
 587         }
 588
 589         ohdr = (struct ipv6_rpl_sr_hdr *)buf;
 590         ipv6_rpl_srh_decompress(ohdr, hdr, &ipv6_hdr(skb)->daddr, n);
 591         chdr = (struct ipv6_rpl_sr_hdr *)(buf + ((ohdr->hdrlen + 1) << 3));
 592
 593         if ((ipv6_addr_type(&ipv6_hdr(skb)->daddr) & IPV6_ADDR_MULTICAST) ||
 594             (ipv6_addr_type(&ohdr->rpl_segaddr[i]) & IPV6_ADDR_MULTICAST)) {
 595                 kfree_skb(skb);
 596                 kfree(buf);
 597                 return -1;
 598         }
 599
 600         err = ipv6_chk_rpl_srh_loop(net, ohdr->rpl_segaddr, n + 1);
 601         if (err) {
 602                 icmpv6_send(skb, ICMPV6_PARAMPROB, 0, 0);
 603                 kfree_skb(skb);
 604                 kfree(buf);
 605                 return -1;
 606         }
 607
 608         swap(ipv6_hdr(skb)->daddr, ohdr->rpl_segaddr[i]);
 609
 610         ipv6_rpl_srh_compress(chdr, ohdr, &ipv6_hdr(skb)->daddr, n);
 611
 612         oldhdr = ipv6_hdr(skb);
 613
 614         skb_pull(skb, ((hdr->hdrlen + 1) << 3));
 615         skb_postpull_rcsum(skb, oldhdr,
 616                            sizeof(struct ipv6hdr) + ((hdr->hdrlen + 1) << 3));
 617         if (unlikely(!hdr->segments_left)) {
 618                 if (pskb_expand_head(skb, sizeof(struct ipv6hdr) + ((chdr->hdrlen + 1) << 3), 0,
 619                                      GFP_ATOMIC)) {
 620                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_OUTDISCARDS);
 621                         kfree_skb(skb);
 622                         kfree(buf);
 623                         return -1;
 624                 }
 625
 626                 oldhdr = ipv6_hdr(skb);
 627         }
 628         skb_push(skb, ((chdr->hdrlen + 1) << 3) + sizeof(struct ipv6hdr));
 629         skb_reset_network_header(skb);
 630         skb_mac_header_rebuild(skb);
 631         skb_set_transport_header(skb, sizeof(struct ipv6hdr));
 632
 633         memmove(ipv6_hdr(skb), oldhdr, sizeof(struct ipv6hdr));
 634         memcpy(skb_transport_header(skb), chdr, (chdr->hdrlen + 1) << 3);
 635
 636         ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 637         skb_postpush_rcsum(skb, ipv6_hdr(skb),
 638                            sizeof(struct ipv6hdr) + ((chdr->hdrlen + 1) << 3));
 639
 640         kfree(buf);
 641
 642         skb_dst_drop(skb);
 643
 644         ip6_route_input(skb);
 645
 646         if (skb_dst(skb)->error) {
 647                 dst_input(skb);
 648                 return -1;
 649         }
 650
 651         if (skb_dst(skb)->dev->flags & IFF_LOOPBACK) {
 652                 if (ipv6_hdr(skb)->hop_limit <= 1) {
 653                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 654                         icmpv6_send(skb, ICMPV6_TIME_EXCEED,
 655                                     ICMPV6_EXC_HOPLIMIT, 0);
 656                         kfree_skb(skb);
 657                         return -1;
 658                 }
 659                 ipv6_hdr(skb)->hop_limit--;
 660
 661                 skb_pull(skb, sizeof(struct ipv6hdr));
 662                 goto looped_back;
 663         }
 664
 665         dst_input(skb);
 666
 667         return -1;
 668 }
 669
 670 /********************************
 671   Routing header.
 672  ********************************/
 673
 674 /* called with rcu_read_lock() */
 675 static int ipv6_rthdr_rcv(struct sk_buff *skb)
 676 {
 677         struct inet6_dev *idev = __in6_dev_get(skb->dev);
 678         struct inet6_skb_parm *opt = IP6CB(skb);
 679         struct in6_addr *addr = NULL;
 680         struct in6_addr daddr;
 681         int n, i;
 682         struct ipv6_rt_hdr *hdr;
 683         struct rt0_hdr *rthdr;
 684         struct net *net = dev_net(skb->dev);
 685         int accept_source_route = net->ipv6.devconf_all->accept_source_route;
 686
 687         if (idev && accept_source_route > idev->cnf.accept_source_route)
 688                 accept_source_route = idev->cnf.accept_source_route;
 689
 690         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 691             !pskb_may_pull(skb, (skb_transport_offset(skb) +
 692                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 693                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 694                 kfree_skb(skb);
 695                 return -1;
 696         }
 697
 698         hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 699
 700         if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ||
 701             skb->pkt_type != PACKET_HOST) {
 702                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 703                 kfree_skb(skb);
 704                 return -1;
 705         }
 706
 707         switch (hdr->type) {
 708         case IPV6_SRCRT_TYPE_4:
 709                 /* segment routing */
 710                 return ipv6_srh_rcv(skb);
 711         case IPV6_SRCRT_TYPE_3:
 712                 /* rpl segment routing */
 713                 return ipv6_rpl_srh_rcv(skb);
 714         default:
 715                 break;
 716         }
 717
 718 looped_back:
 719         if (hdr->segments_left == 0) {
 720                 switch (hdr->type) {
 721 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 722                 case IPV6_SRCRT_TYPE_2:
 723                         /* Silently discard type 2 header unless it was
 724                          * processed by own
 725                          */
 726                         if (!addr) {
 727                                 __IP6_INC_STATS(net, idev,
 728                                                 IPSTATS_MIB_INADDRERRORS);
 729                                 kfree_skb(skb);
 730                                 return -1;
 731                         }
 732                         break;
 733 #endif
 734                 default:
 735                         break;
 736                 }
 737
 738                 opt->lastopt = opt->srcrt = skb_network_header_len(skb);
 739                 skb->transport_header += (hdr->hdrlen + 1) << 3;
 740                 opt->dst0 = opt->dst1;
 741                 opt->dst1 = 0;
 742                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
 743                 return 1;
 744         }
 745
 746         switch (hdr->type) {
 747 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 748         case IPV6_SRCRT_TYPE_2:
 749                 if (accept_source_route < 0)
 750                         goto unknown_rh;
 751                 /* Silently discard invalid RTH type 2 */
 752                 if (hdr->hdrlen != 2 || hdr->segments_left != 1) {
 753                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 754                         kfree_skb(skb);
 755                         return -1;
 756                 }
 757                 break;
 758 #endif
 759         default:
 760                 goto unknown_rh;
 761         }
 762
 763         /*
 764          *      This is the routing header forwarding algorithm from
 765          *      RFC 2460, page 16.
 766          */
 767
 768         n = hdr->hdrlen >> 1;
 769
 770         if (hdr->segments_left > n) {
 771                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 772                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 773                                   ((&hdr->segments_left) -
 774                                    skb_network_header(skb)));
 775                 return -1;
 776         }
 777
 778         /* We are about to mangle packet header. Be careful!
 779            Do not damage packets queued somewhere.
 780          */
 781         if (skb_cloned(skb)) {
 782                 /* the copy is a forwarded packet */
 783                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
 784                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 785                                         IPSTATS_MIB_OUTDISCARDS);
 786                         kfree_skb(skb);
 787                         return -1;
 788                 }
 789                 hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 790         }
 791
 792         if (skb->ip_summed == CHECKSUM_COMPLETE)
 793                 skb->ip_summed = CHECKSUM_NONE;
 794
 795         i = n - --hdr->segments_left;
 796
 797         rthdr = (struct rt0_hdr *) hdr;
 798         addr = rthdr->addr;
 799         addr += i - 1;
 800
 801         switch (hdr->type) {
 802 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 803         case IPV6_SRCRT_TYPE_2:
 804                 if (xfrm6_input_addr(skb, (xfrm_address_t *)addr,
 805                                      (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 806                                      IPPROTO_ROUTING) < 0) {
 807                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 808                         kfree_skb(skb);
 809                         return -1;
 810                 }
 811                 if (!ipv6_chk_home_addr(dev_net(skb_dst(skb)->dev), addr)) {
 812                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 813                         kfree_skb(skb);
 814                         return -1;
 815                 }
 816                 break;
 817 #endif
 818         default:
 819                 break;
 820         }
 821
 822         if (ipv6_addr_is_multicast(addr)) {
 823                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 824                 kfree_skb(skb);
 825                 return -1;
 826         }
 827
 828         daddr = *addr;
 829         *addr = ipv6_hdr(skb)->daddr;
 830         ipv6_hdr(skb)->daddr = daddr;
 831
 832         skb_dst_drop(skb);
 833         ip6_route_input(skb);
 834         if (skb_dst(skb)->error) {
 835                 skb_push(skb, skb->data - skb_network_header(skb));
 836                 dst_input(skb);
 837                 return -1;
 838         }
 839
 840         if (skb_dst(skb)->dev->flags&IFF_LOOPBACK) {
 841                 if (ipv6_hdr(skb)->hop_limit <= 1) {
 842                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 843                         icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
 844                                     0);
 845                         kfree_skb(skb);
 846                         return -1;
 847                 }
 848                 ipv6_hdr(skb)->hop_limit--;
 849                 goto looped_back;
 850         }
 851
 852         skb_push(skb, skb->data - skb_network_header(skb));
 853         dst_input(skb);
 854         return -1;
 855
 856 unknown_rh:
 857         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 858         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 859                           (&hdr->type) - skb_network_header(skb));
 860         return -1;
 861 }
 862
 863 static const struct inet6_protocol rthdr_protocol = {
 864         .handler        =       ipv6_rthdr_rcv,
 865         .flags          =       INET6_PROTO_NOPOLICY,
 866 };
 867
 868 static const struct inet6_protocol destopt_protocol = {
 869         .handler        =       ipv6_destopt_rcv,
 870         .flags          =       INET6_PROTO_NOPOLICY,
 871 };
 872
 873 static const struct inet6_protocol nodata_protocol = {
 874         .handler        =       dst_discard,
 875         .flags          =       INET6_PROTO_NOPOLICY,
 876 };
 877
 878 int __init ipv6_exthdrs_init(void)
 879 {
 880         int ret;
 881
 882         ret = inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 883         if (ret)
 884                 goto out;
 885
 886         ret = inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 887         if (ret)
 888                 goto out_rthdr;
 889
 890         ret = inet6_add_protocol(&nodata_protocol, IPPROTO_NONE);
 891         if (ret)
 892                 goto out_destopt;
 893
 894 out:
 895         return ret;
 896 out_destopt:
 897         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 898 out_rthdr:
 899         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 900         goto out;
 901 };
 902
 903 void ipv6_exthdrs_exit(void)
 904 {
 905         inet6_del_protocol(&nodata_protocol, IPPROTO_NONE);
 906         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 907         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 908 }
 909
 910 /**********************************
 911   Hop-by-hop options.
 912  **********************************/
 913
 914 /*
 915  * Note: we cannot rely on skb_dst(skb) before we assign it in ip6_route_input().
 916  */
 917 static inline struct net *ipv6_skb_net(struct sk_buff *skb)
 918 {
 919         return skb_dst(skb) ? dev_net(skb_dst(skb)->dev) : dev_net(skb->dev);
 920 }
 921
 922 /* Router Alert as of RFC 2711 */
 923
 924 static bool ipv6_hop_ra(struct sk_buff *skb, int optoff)
 925 {
 926         const unsigned char *nh = skb_network_header(skb);
 927
 928         if (nh[optoff + 1] == 2) {
 929                 IP6CB(skb)->flags |= IP6SKB_ROUTERALERT;
 930                 memcpy(&IP6CB(skb)->ra, nh + optoff + 2, sizeof(IP6CB(skb)->ra));
 931                 return true;
 932         }
 933         net_dbg_ratelimited("ipv6_hop_ra: wrong RA length %d\n",
 934                             nh[optoff + 1]);
 935         kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR);
 936         return false;
 937 }
 938
 939 /* IOAM */
 940
 941 static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff)
 942 {
 943         struct ioam6_trace_hdr *trace;
 944         struct ioam6_namespace *ns;
 945         struct ioam6_hdr *hdr;
 946
 947         /* Bad alignment (must be 4n-aligned) */
 948         if (optoff & 3)
 949                 goto drop;
 950
 951         /* Ignore if IOAM is not enabled on ingress */
 952         if (!__in6_dev_get(skb->dev)->cnf.ioam6_enabled)
 953                 goto ignore;
 954
 955         /* Truncated Option header */
 956         hdr = (struct ioam6_hdr *)(skb_network_header(skb) + optoff);
 957         if (hdr->opt_len < 2)
 958                 goto drop;
 959
 960         switch (hdr->type) {
 961         case IOAM6_TYPE_PREALLOC:
 962                 /* Truncated Pre-allocated Trace header */
 963                 if (hdr->opt_len < 2 + sizeof(*trace))
 964                         goto drop;
 965
 966                 /* Malformed Pre-allocated Trace header */
 967                 trace = (struct ioam6_trace_hdr *)((u8 *)hdr + sizeof(*hdr));
 968                 if (hdr->opt_len < 2 + sizeof(*trace) + trace->remlen * 4)
 969                         goto drop;
 970
 971                 /* Ignore if the IOAM namespace is unknown */
 972                 ns = ioam6_namespace(ipv6_skb_net(skb), trace->namespace_id);
 973                 if (!ns)
 974                         goto ignore;
 975
 976                 if (!skb_valid_dst(skb))
 977                         ip6_route_input(skb);
 978
 979                 /* About to mangle packet header */
 980                 if (skb_ensure_writable(skb, optoff + 2 + hdr->opt_len))
 981                         goto drop;
 982
 983                 /* Trace pointer may have changed */
 984                 trace = (struct ioam6_trace_hdr *)(skb_network_header(skb)
 985                                                    + optoff + sizeof(*hdr));
 986
 987                 ioam6_fill_trace_data(skb, ns, trace, true);
 988                 break;
 989         default:
 990                 break;
 991         }
 992
 993 ignore:
 994         return true;
 995
 996 drop:
 997         kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR);
 998         return false;
 999 }
1000
1001 /* Jumbo payload */
1002
1003 static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
1004 {
1005         const unsigned char *nh = skb_network_header(skb);
1006         SKB_DR(reason);
1007         u32 pkt_len;
1008
1009         if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
1010                 net_dbg_ratelimited("ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
1011                                     nh[optoff+1]);
1012                 SKB_DR_SET(reason, IP_INHDR);
1013                 goto drop;
1014         }
1015
1016         pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
1017         if (pkt_len <= IPV6_MAXPLEN) {
1018                 icmpv6_param_prob_reason(skb, ICMPV6_HDR_FIELD, optoff + 2,
1019                                          SKB_DROP_REASON_IP_INHDR);
1020                 return false;
1021         }
1022         if (ipv6_hdr(skb)->payload_len) {
1023                 icmpv6_param_prob_reason(skb, ICMPV6_HDR_FIELD, optoff,
1024                                          SKB_DROP_REASON_IP_INHDR);
1025                 return false;
1026         }
1027
1028         if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
1029                 SKB_DR_SET(reason, PKT_TOO_SMALL);
1030                 goto drop;
1031         }
1032
1033         if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
1034                 goto drop;
1035
1036         IP6CB(skb)->flags |= IP6SKB_JUMBOGRAM;
1037         return true;
1038
1039 drop:
1040         kfree_skb_reason(skb, reason);
1041         return false;
1042 }
1043
1044 /* CALIPSO RFC 5570 */
1045
1046 static bool ipv6_hop_calipso(struct sk_buff *skb, int optoff)
1047 {
1048         const unsigned char *nh = skb_network_header(skb);
1049
1050         if (nh[optoff + 1] < 8)
1051                 goto drop;
1052
1053         if (nh[optoff + 6] * 4 + 8 > nh[optoff + 1])
1054                 goto drop;
1055
1056         if (!calipso_validate(skb, nh + optoff))
1057                 goto drop;
1058
1059         return true;
1060
1061 drop:
1062         kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR);
1063         return false;
1064 }
1065
1066 int ipv6_parse_hopopts(struct sk_buff *skb)
1067 {
1068         struct inet6_skb_parm *opt = IP6CB(skb);
1069         struct net *net = dev_net(skb->dev);
1070         int extlen;
1071
1072         /*
1073          * skb_network_header(skb) is equal to skb->data, and
1074          * skb_network_header_len(skb) is always equal to
1075          * sizeof(struct ipv6hdr) by definition of
1076          * hop-by-hop options.
1077          */
1078         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
1079             !pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
1080                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
1081 fail_and_free:
1082                 kfree_skb(skb);
1083                 return -1;
1084         }
1085
1086         extlen = (skb_transport_header(skb)[1] + 1) << 3;
1087         if (extlen > net->ipv6.sysctl.max_hbh_opts_len)
1088                 goto fail_and_free;
1089
1090         opt->flags |= IP6SKB_HOPBYHOP;
1091         if (ip6_parse_tlv(true, skb, net->ipv6.sysctl.max_hbh_opts_cnt)) {
1092                 skb->transport_header += extlen;
1093                 opt = IP6CB(skb);
1094                 opt->nhoff = sizeof(struct ipv6hdr);
1095                 return 1;
1096         }
1097         return -1;
1098 }
1099
1100 /*
1101  *      Creating outbound headers.
1102  *
1103  *      "build" functions work when skb is filled from head to tail (datagram)
1104  *      "push"  functions work when headers are added from tail to head (tcp)
1105  *
1106  *      In both cases we assume, that caller reserved enough room
1107  *      for headers.
1108  */
1109
1110 static void ipv6_push_rthdr0(struct sk_buff *skb, u8 *proto,
1111                              struct ipv6_rt_hdr *opt,
1112                              struct in6_addr **addr_p, struct in6_addr *saddr)
1113 {
1114         struct rt0_hdr *phdr, *ihdr;
1115         int hops;
1116
1117         ihdr = (struct rt0_hdr *) opt;
1118
1119         phdr = skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
1120         memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
1121
1122         hops = ihdr->rt_hdr.hdrlen >> 1;
1123
1124         if (hops > 1)
1125                 memcpy(phdr->addr, ihdr->addr + 1,
1126                        (hops - 1) * sizeof(struct in6_addr));
1127
1128         phdr->addr[hops - 1] = **addr_p;
1129         *addr_p = ihdr->addr;
1130
1131         phdr->rt_hdr.nexthdr = *proto;
1132         *proto = NEXTHDR_ROUTING;
1133 }
1134
1135 static void ipv6_push_rthdr4(struct sk_buff *skb, u8 *proto,
1136                              struct ipv6_rt_hdr *opt,
1137                              struct in6_addr **addr_p, struct in6_addr *saddr)
1138 {
1139         struct ipv6_sr_hdr *sr_phdr, *sr_ihdr;
1140         int plen, hops;
1141
1142         sr_ihdr = (struct ipv6_sr_hdr *)opt;
1143         plen = (sr_ihdr->hdrlen + 1) << 3;
1144
1145         sr_phdr = skb_push(skb, plen);
1146         memcpy(sr_phdr, sr_ihdr, sizeof(struct ipv6_sr_hdr));
1147
1148         hops = sr_ihdr->first_segment + 1;
1149         memcpy(sr_phdr->segments + 1, sr_ihdr->segments + 1,
1150                (hops - 1) * sizeof(struct in6_addr));
1151
1152         sr_phdr->segments[0] = **addr_p;
1153         *addr_p = &sr_ihdr->segments[sr_ihdr->segments_left];
1154
1155         if (sr_ihdr->hdrlen > hops * 2) {
1156                 int tlvs_offset, tlvs_length;
1157
1158                 tlvs_offset = (1 + hops * 2) << 3;
1159                 tlvs_length = (sr_ihdr->hdrlen - hops * 2) << 3;
1160                 memcpy((char *)sr_phdr + tlvs_offset,
1161                        (char *)sr_ihdr + tlvs_offset, tlvs_length);
1162         }
1163
1164 #ifdef CONFIG_IPV6_SEG6_HMAC
1165         if (sr_has_hmac(sr_phdr)) {
1166                 struct net *net = NULL;
1167
1168                 if (skb->dev)
1169                         net = dev_net(skb->dev);
1170                 else if (skb->sk)
1171                         net = sock_net(skb->sk);
1172
1173                 WARN_ON(!net);
1174
1175                 if (net)
1176                         seg6_push_hmac(net, saddr, sr_phdr);
1177         }
1178 #endif
1179
1180         sr_phdr->nexthdr = *proto;
1181         *proto = NEXTHDR_ROUTING;
1182 }
1183
1184 static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
1185                             struct ipv6_rt_hdr *opt,
1186                             struct in6_addr **addr_p, struct in6_addr *saddr)
1187 {
1188         switch (opt->type) {
1189         case IPV6_SRCRT_TYPE_0:
1190         case IPV6_SRCRT_STRICT:
1191         case IPV6_SRCRT_TYPE_2:
1192                 ipv6_push_rthdr0(skb, proto, opt, addr_p, saddr);
1193                 break;
1194         case IPV6_SRCRT_TYPE_4:
1195                 ipv6_push_rthdr4(skb, proto, opt, addr_p, saddr);
1196                 break;
1197         default:
1198                 break;
1199         }
1200 }
1201
1202 static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
1203 {
1204         struct ipv6_opt_hdr *h = skb_push(skb, ipv6_optlen(opt));
1205
1206         memcpy(h, opt, ipv6_optlen(opt));
1207         h->nexthdr = *proto;
1208         *proto = type;
1209 }
1210
1211 void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
1212                           u8 *proto,
1213                           struct in6_addr **daddr, struct in6_addr *saddr)
1214 {
1215         if (opt->srcrt) {
1216                 ipv6_push_rthdr(skb, proto, opt->srcrt, daddr, saddr);
1217                 /*
1218                  * IPV6_RTHDRDSTOPTS is ignored
1219                  * unless IPV6_RTHDR is set (RFC3542).
1220                  */
1221                 if (opt->dst0opt)
1222                         ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
1223         }
1224         if (opt->hopopt)
1225                 ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
1226 }
1227
1228 void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
1229 {
1230         if (opt->dst1opt)
1231                 ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
1232 }
1233 EXPORT_SYMBOL(ipv6_push_frag_opts);
1234
1235 struct ipv6_txoptions *
1236 ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
1237 {
1238         struct ipv6_txoptions *opt2;
1239
1240         opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
1241         if (opt2) {
1242                 long dif = (char *)opt2 - (char *)opt;
1243                 memcpy(opt2, opt, opt->tot_len);
1244                 if (opt2->hopopt)
1245                         *((char **)&opt2->hopopt) += dif;
1246                 if (opt2->dst0opt)
1247                         *((char **)&opt2->dst0opt) += dif;
1248                 if (opt2->dst1opt)
1249                         *((char **)&opt2->dst1opt) += dif;
1250                 if (opt2->srcrt)
1251                         *((char **)&opt2->srcrt) += dif;
1252                 refcount_set(&opt2->refcnt, 1);
1253         }
1254         return opt2;
1255 }
1256 EXPORT_SYMBOL_GPL(ipv6_dup_options);
1257
1258 static void ipv6_renew_option(int renewtype,
1259                               struct ipv6_opt_hdr **dest,
1260                               struct ipv6_opt_hdr *old,
1261                               struct ipv6_opt_hdr *new,
1262                               int newtype, char **p)
1263 {
1264         struct ipv6_opt_hdr *src;
1265
1266         src = (renewtype == newtype ? new : old);
1267         if (!src)
1268                 return;
1269
1270         memcpy(*p, src, ipv6_optlen(src));
1271         *dest = (struct ipv6_opt_hdr *)*p;
1272         *p += CMSG_ALIGN(ipv6_optlen(*dest));
1273 }
1274
1275 /**
1276  * ipv6_renew_options - replace a specific ext hdr with a new one.
1277  *
1278  * @sk: sock from which to allocate memory
1279  * @opt: original options
1280  * @newtype: option type to replace in @opt
1281  * @newopt: new option of type @newtype to replace (user-mem)
1282  *
1283  * Returns a new set of options which is a copy of @opt with the
1284  * option type @newtype replaced with @newopt.
1285  *
1286  * @opt may be NULL, in which case a new set of options is returned
1287  * containing just @newopt.
1288  *
1289  * @newopt may be NULL, in which case the specified option type is
1290  * not copied into the new set of options.
1291  *
1292  * The new set of options is allocated from the socket option memory
1293  * buffer of @sk.
1294  */
1295 struct ipv6_txoptions *
1296 ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
1297                    int newtype, struct ipv6_opt_hdr *newopt)
1298 {
1299         int tot_len = 0;
1300         char *p;
1301         struct ipv6_txoptions *opt2;
1302
1303         if (opt) {
1304                 if (newtype != IPV6_HOPOPTS && opt->hopopt)
1305                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
1306                 if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
1307                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
1308                 if (newtype != IPV6_RTHDR && opt->srcrt)
1309                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
1310                 if (newtype != IPV6_DSTOPTS && opt->dst1opt)
1311                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
1312         }
1313
1314         if (newopt)
1315                 tot_len += CMSG_ALIGN(ipv6_optlen(newopt));
1316
1317         if (!tot_len)
1318                 return NULL;
1319
1320         tot_len += sizeof(*opt2);
1321         opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
1322         if (!opt2)
1323                 return ERR_PTR(-ENOBUFS);
1324
1325         memset(opt2, 0, tot_len);
1326         refcount_set(&opt2->refcnt, 1);
1327         opt2->tot_len = tot_len;
1328         p = (char *)(opt2 + 1);
1329
1330         ipv6_renew_option(IPV6_HOPOPTS, &opt2->hopopt,
1331                           (opt ? opt->hopopt : NULL),
1332                           newopt, newtype, &p);
1333         ipv6_renew_option(IPV6_RTHDRDSTOPTS, &opt2->dst0opt,
1334                           (opt ? opt->dst0opt : NULL),
1335                           newopt, newtype, &p);
1336         ipv6_renew_option(IPV6_RTHDR,
1337                           (struct ipv6_opt_hdr **)&opt2->srcrt,
1338                           (opt ? (struct ipv6_opt_hdr *)opt->srcrt : NULL),
1339                           newopt, newtype, &p);
1340         ipv6_renew_option(IPV6_DSTOPTS, &opt2->dst1opt,
1341                           (opt ? opt->dst1opt : NULL),
1342                           newopt, newtype, &p);
1343
1344         opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
1345                           (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
1346                           (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
1347         opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
1348
1349         return opt2;
1350 }
1351
1352 struct ipv6_txoptions *__ipv6_fixup_options(struct ipv6_txoptions *opt_space,
1353                                             struct ipv6_txoptions *opt)
1354 {
1355         /*
1356          * ignore the dest before srcrt unless srcrt is being included.
1357          * --yoshfuji
1358          */
1359         if (opt->dst0opt && !opt->srcrt) {
1360                 if (opt_space != opt) {
1361                         memcpy(opt_space, opt, sizeof(*opt_space));
1362                         opt = opt_space;
1363                 }
1364                 opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
1365                 opt->dst0opt = NULL;
1366         }
1367
1368         return opt;
1369 }
1370 EXPORT_SYMBOL_GPL(__ipv6_fixup_options);
1371
1372 /**
1373  * fl6_update_dst - update flowi destination address with info given
1374  *                  by srcrt option, if any.
1375  *
1376  * @fl6: flowi6 for which daddr is to be updated
1377  * @opt: struct ipv6_txoptions in which to look for srcrt opt
1378  * @orig: copy of original daddr address if modified
1379  *
1380  * Returns NULL if no txoptions or no srcrt, otherwise returns orig
1381  * and initial value of fl6->daddr set in orig
1382  */
1383 struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
1384                                 const struct ipv6_txoptions *opt,
1385                                 struct in6_addr *orig)
1386 {
1387         if (!opt || !opt->srcrt)
1388                 return NULL;
1389
1390         *orig = fl6->daddr;
1391
1392         switch (opt->srcrt->type) {
1393         case IPV6_SRCRT_TYPE_0:
1394         case IPV6_SRCRT_STRICT:
1395         case IPV6_SRCRT_TYPE_2:
1396                 fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr;
1397                 break;
1398         case IPV6_SRCRT_TYPE_4:
1399         {
1400                 struct ipv6_sr_hdr *srh = (struct ipv6_sr_hdr *)opt->srcrt;
1401
1402                 fl6->daddr = srh->segments[srh->segments_left];
1403                 break;
1404         }
1405         default:
1406                 return NULL;
1407         }
1408
1409         return orig;
1410 }
1411 EXPORT_SYMBOL_GPL(fl6_update_dst);