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