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         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                                         break;
 184                                 case IPV6_TLV_JUMBO:
 185                                         if (!ipv6_hop_jumbo(skb, off))
 186                                                 return false;
 187                                         break;
 188                                 case IPV6_TLV_CALIPSO:
 189                                         if (!ipv6_hop_calipso(skb, off))
 190                                                 return false;
 191                                         break;
 192                                 default:
 193                                         if (!ip6_tlvopt_unknown(skb, off,
 194                                                                 disallow_unknowns))
 195                                                 return false;
 196                                         break;
 197                                 }
 198                         } else {
 199                                 switch (nh[off]) {
 200 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 201                                 case IPV6_TLV_HAO:
 202                                         if (!ipv6_dest_hao(skb, off))
 203                                                 return false;
 204                                         break;
 205 #endif
 206                                 default:
 207                                         if (!ip6_tlvopt_unknown(skb, off,
 208                                                                 disallow_unknowns))
 209                                                 return false;
 210                                         break;
 211                                 }
 212                         }
 213                         padlen = 0;
 214                 }
 215                 off += optlen;
 216                 len -= optlen;
 217         }
 218
 219         if (len == 0)
 220                 return true;
 221 bad:
 222         kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR);
 223         return false;
 224 }
 225
 226 /*****************************
 227   Destination options header.
 228  *****************************/
 229
 230 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 231 static bool ipv6_dest_hao(struct sk_buff *skb, int optoff)
 232 {
 233         struct ipv6_destopt_hao *hao;
 234         struct inet6_skb_parm *opt = IP6CB(skb);
 235         struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 236         SKB_DR(reason);
 237         int ret;
 238
 239         if (opt->dsthao) {
 240                 net_dbg_ratelimited("hao duplicated\n");
 241                 goto discard;
 242         }
 243         opt->dsthao = opt->dst1;
 244         opt->dst1 = 0;
 245
 246         hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) + optoff);
 247
 248         if (hao->length != 16) {
 249                 net_dbg_ratelimited("hao invalid option length = %d\n",
 250                                     hao->length);
 251                 SKB_DR_SET(reason, IP_INHDR);
 252                 goto discard;
 253         }
 254
 255         if (!(ipv6_addr_type(&hao->addr) & IPV6_ADDR_UNICAST)) {
 256                 net_dbg_ratelimited("hao is not an unicast addr: %pI6\n",
 257                                     &hao->addr);
 258                 SKB_DR_SET(reason, INVALID_PROTO);
 259                 goto discard;
 260         }
 261
 262         ret = xfrm6_input_addr(skb, (xfrm_address_t *)&ipv6h->daddr,
 263                                (xfrm_address_t *)&hao->addr, IPPROTO_DSTOPTS);
 264         if (unlikely(ret < 0)) {
 265                 SKB_DR_SET(reason, XFRM_POLICY);
 266                 goto discard;
 267         }
 268
 269         if (skb_cloned(skb)) {
 270                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 271                         goto discard;
 272
 273                 /* update all variable using below by copied skbuff */
 274                 hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) +
 275                                                   optoff);
 276                 ipv6h = ipv6_hdr(skb);
 277         }
 278
 279         if (skb->ip_summed == CHECKSUM_COMPLETE)
 280                 skb->ip_summed = CHECKSUM_NONE;
 281
 282         swap(ipv6h->saddr, hao->addr);
 283
 284         if (skb->tstamp == 0)
 285                 __net_timestamp(skb);
 286
 287         return true;
 288
 289  discard:
 290         kfree_skb_reason(skb, reason);
 291         return false;
 292 }
 293 #endif
 294
 295 static int ipv6_destopt_rcv(struct sk_buff *skb)
 296 {
 297         struct inet6_dev *idev = __in6_dev_get(skb->dev);
 298         struct inet6_skb_parm *opt = IP6CB(skb);
 299 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 300         __u16 dstbuf;
 301 #endif
 302         struct dst_entry *dst = skb_dst(skb);
 303         struct net *net = dev_net(skb->dev);
 304         int extlen;
 305
 306         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 307             !pskb_may_pull(skb, (skb_transport_offset(skb) +
 308                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 309                 __IP6_INC_STATS(dev_net(dst->dev), idev,
 310                                 IPSTATS_MIB_INHDRERRORS);
 311 fail_and_free:
 312                 kfree_skb(skb);
 313                 return -1;
 314         }
 315
 316         extlen = (skb_transport_header(skb)[1] + 1) << 3;
 317         if (extlen > net->ipv6.sysctl.max_dst_opts_len)
 318                 goto fail_and_free;
 319
 320         opt->lastopt = opt->dst1 = skb_network_header_len(skb);
 321 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 322         dstbuf = opt->dst1;
 323 #endif
 324
 325         if (ip6_parse_tlv(false, skb, net->ipv6.sysctl.max_dst_opts_cnt)) {
 326                 skb->transport_header += extlen;
 327                 opt = IP6CB(skb);
 328 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 329                 opt->nhoff = dstbuf;
 330 #else
 331                 opt->nhoff = opt->dst1;
 332 #endif
 333                 return 1;
 334         }
 335
 336         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 337         return -1;
 338 }
 339
 340 static void seg6_update_csum(struct sk_buff *skb)
 341 {
 342         struct ipv6_sr_hdr *hdr;
 343         struct in6_addr *addr;
 344         __be32 from, to;
 345
 346         /* srh is at transport offset and seg_left is already decremented
 347          * but daddr is not yet updated with next segment
 348          */
 349
 350         hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
 351         addr = hdr->segments + hdr->segments_left;
 352
 353         hdr->segments_left++;
 354         from = *(__be32 *)hdr;
 355
 356         hdr->segments_left--;
 357         to = *(__be32 *)hdr;
 358
 359         /* update skb csum with diff resulting from seg_left decrement */
 360
 361         update_csum_diff4(skb, from, to);
 362
 363         /* compute csum diff between current and next segment and update */
 364
 365         update_csum_diff16(skb, (__be32 *)(&ipv6_hdr(skb)->daddr),
 366                            (__be32 *)addr);
 367 }
 368
 369 static int ipv6_srh_rcv(struct sk_buff *skb)
 370 {
 371         struct inet6_skb_parm *opt = IP6CB(skb);
 372         struct net *net = dev_net(skb->dev);
 373         struct ipv6_sr_hdr *hdr;
 374         struct inet6_dev *idev;
 375         struct in6_addr *addr;
 376         int accept_seg6;
 377
 378         hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
 379
 380         idev = __in6_dev_get(skb->dev);
 381
 382         accept_seg6 = net->ipv6.devconf_all->seg6_enabled;
 383         if (accept_seg6 > idev->cnf.seg6_enabled)
 384                 accept_seg6 = idev->cnf.seg6_enabled;
 385
 386         if (!accept_seg6) {
 387                 kfree_skb(skb);
 388                 return -1;
 389         }
 390
 391 #ifdef CONFIG_IPV6_SEG6_HMAC
 392         if (!seg6_hmac_validate_skb(skb)) {
 393                 kfree_skb(skb);
 394                 return -1;
 395         }
 396 #endif
 397
 398 looped_back:
 399         if (hdr->segments_left == 0) {
 400                 if (hdr->nexthdr == NEXTHDR_IPV6 || hdr->nexthdr == NEXTHDR_IPV4) {
 401                         int offset = (hdr->hdrlen + 1) << 3;
 402
 403                         skb_postpull_rcsum(skb, skb_network_header(skb),
 404                                            skb_network_header_len(skb));
 405
 406                         if (!pskb_pull(skb, offset)) {
 407                                 kfree_skb(skb);
 408                                 return -1;
 409                         }
 410                         skb_postpull_rcsum(skb, skb_transport_header(skb),
 411                                            offset);
 412
 413                         skb_reset_network_header(skb);
 414                         skb_reset_transport_header(skb);
 415                         skb->encapsulation = 0;
 416                         if (hdr->nexthdr == NEXTHDR_IPV4)
 417                                 skb->protocol = htons(ETH_P_IP);
 418                         __skb_tunnel_rx(skb, skb->dev, net);
 419
 420                         netif_rx(skb);
 421                         return -1;
 422                 }
 423
 424                 opt->srcrt = skb_network_header_len(skb);
 425                 opt->lastopt = opt->srcrt;
 426                 skb->transport_header += (hdr->hdrlen + 1) << 3;
 427                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
 428
 429                 return 1;
 430         }
 431
 432         if (hdr->segments_left >= (hdr->hdrlen >> 1)) {
 433                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 434                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 435                                   ((&hdr->segments_left) -
 436                                    skb_network_header(skb)));
 437                 return -1;
 438         }
 439
 440         if (skb_cloned(skb)) {
 441                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
 442                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 443                                         IPSTATS_MIB_OUTDISCARDS);
 444                         kfree_skb(skb);
 445                         return -1;
 446                 }
 447         }
 448
 449         hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
 450
 451         hdr->segments_left--;
 452         addr = hdr->segments + hdr->segments_left;
 453
 454         skb_push(skb, sizeof(struct ipv6hdr));
 455
 456         if (skb->ip_summed == CHECKSUM_COMPLETE)
 457                 seg6_update_csum(skb);
 458
 459         ipv6_hdr(skb)->daddr = *addr;
 460
 461         skb_dst_drop(skb);
 462
 463         ip6_route_input(skb);
 464
 465         if (skb_dst(skb)->error) {
 466                 dst_input(skb);
 467                 return -1;
 468         }
 469
 470         if (skb_dst(skb)->dev->flags & IFF_LOOPBACK) {
 471                 if (ipv6_hdr(skb)->hop_limit <= 1) {
 472                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 473                         icmpv6_send(skb, ICMPV6_TIME_EXCEED,
 474                                     ICMPV6_EXC_HOPLIMIT, 0);
 475                         kfree_skb(skb);
 476                         return -1;
 477                 }
 478                 ipv6_hdr(skb)->hop_limit--;
 479
 480                 skb_pull(skb, sizeof(struct ipv6hdr));
 481                 goto looped_back;
 482         }
 483
 484         dst_input(skb);
 485
 486         return -1;
 487 }
 488
 489 static int ipv6_rpl_srh_rcv(struct sk_buff *skb)
 490 {
 491         struct ipv6_rpl_sr_hdr *hdr, *ohdr, *chdr;
 492         struct inet6_skb_parm *opt = IP6CB(skb);
 493         struct net *net = dev_net(skb->dev);
 494         struct inet6_dev *idev;
 495         struct ipv6hdr *oldhdr;
 496         unsigned char *buf;
 497         int accept_rpl_seg;
 498         int i, err;
 499         u64 n = 0;
 500         u32 r;
 501
 502         idev = __in6_dev_get(skb->dev);
 503
 504         accept_rpl_seg = net->ipv6.devconf_all->rpl_seg_enabled;
 505         if (accept_rpl_seg > idev->cnf.rpl_seg_enabled)
 506                 accept_rpl_seg = idev->cnf.rpl_seg_enabled;
 507
 508         if (!accept_rpl_seg) {
 509                 kfree_skb(skb);
 510                 return -1;
 511         }
 512
 513 looped_back:
 514         hdr = (struct ipv6_rpl_sr_hdr *)skb_transport_header(skb);
 515
 516         if (hdr->segments_left == 0) {
 517                 if (hdr->nexthdr == NEXTHDR_IPV6) {
 518                         int offset = (hdr->hdrlen + 1) << 3;
 519
 520                         skb_postpull_rcsum(skb, skb_network_header(skb),
 521                                            skb_network_header_len(skb));
 522
 523                         if (!pskb_pull(skb, offset)) {
 524                                 kfree_skb(skb);
 525                                 return -1;
 526                         }
 527                         skb_postpull_rcsum(skb, skb_transport_header(skb),
 528                                            offset);
 529
 530                         skb_reset_network_header(skb);
 531                         skb_reset_transport_header(skb);
 532                         skb->encapsulation = 0;
 533
 534                         __skb_tunnel_rx(skb, skb->dev, net);
 535
 536                         netif_rx(skb);
 537                         return -1;
 538                 }
 539
 540                 opt->srcrt = skb_network_header_len(skb);
 541                 opt->lastopt = opt->srcrt;
 542                 skb->transport_header += (hdr->hdrlen + 1) << 3;
 543                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
 544
 545                 return 1;
 546         }
 547
 548         if (!pskb_may_pull(skb, sizeof(*hdr))) {
 549                 kfree_skb(skb);
 550                 return -1;
 551         }
 552
 553         n = (hdr->hdrlen << 3) - hdr->pad - (16 - hdr->cmpre);
 554         r = do_div(n, (16 - hdr->cmpri));
 555         /* checks if calculation was without remainder and n fits into
 556          * unsigned char which is segments_left field. Should not be
 557          * higher than that.
 558          */
 559         if (r || (n + 1) > 255) {
 560                 kfree_skb(skb);
 561                 return -1;
 562         }
 563
 564         if (hdr->segments_left > n + 1) {
 565                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 566                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 567                                   ((&hdr->segments_left) -
 568                                    skb_network_header(skb)));
 569                 return -1;
 570         }
 571
 572         if (skb_cloned(skb)) {
 573                 if (pskb_expand_head(skb, IPV6_RPL_SRH_WORST_SWAP_SIZE, 0,
 574                                      GFP_ATOMIC)) {
 575                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 576                                         IPSTATS_MIB_OUTDISCARDS);
 577                         kfree_skb(skb);
 578                         return -1;
 579                 }
 580         } else {
 581                 err = skb_cow_head(skb, IPV6_RPL_SRH_WORST_SWAP_SIZE);
 582                 if (unlikely(err)) {
 583                         kfree_skb(skb);
 584                         return -1;
 585                 }
 586         }
 587
 588         hdr = (struct ipv6_rpl_sr_hdr *)skb_transport_header(skb);
 589
 590         if (!pskb_may_pull(skb, ipv6_rpl_srh_size(n, hdr->cmpri,
 591                                                   hdr->cmpre))) {
 592                 kfree_skb(skb);
 593                 return -1;
 594         }
 595
 596         hdr->segments_left--;
 597         i = n - hdr->segments_left;
 598
 599         buf = kcalloc(struct_size(hdr, segments.addr, n + 2), 2, GFP_ATOMIC);
 600         if (unlikely(!buf)) {
 601                 kfree_skb(skb);
 602                 return -1;
 603         }
 604
 605         ohdr = (struct ipv6_rpl_sr_hdr *)buf;
 606         ipv6_rpl_srh_decompress(ohdr, hdr, &ipv6_hdr(skb)->daddr, n);
 607         chdr = (struct ipv6_rpl_sr_hdr *)(buf + ((ohdr->hdrlen + 1) << 3));
 608
 609         if ((ipv6_addr_type(&ipv6_hdr(skb)->daddr) & IPV6_ADDR_MULTICAST) ||
 610             (ipv6_addr_type(&ohdr->rpl_segaddr[i]) & IPV6_ADDR_MULTICAST)) {
 611                 kfree_skb(skb);
 612                 kfree(buf);
 613                 return -1;
 614         }
 615
 616         err = ipv6_chk_rpl_srh_loop(net, ohdr->rpl_segaddr, n + 1);
 617         if (err) {
 618                 icmpv6_send(skb, ICMPV6_PARAMPROB, 0, 0);
 619                 kfree_skb(skb);
 620                 kfree(buf);
 621                 return -1;
 622         }
 623
 624         swap(ipv6_hdr(skb)->daddr, ohdr->rpl_segaddr[i]);
 625
 626         ipv6_rpl_srh_compress(chdr, ohdr, &ipv6_hdr(skb)->daddr, n);
 627
 628         oldhdr = ipv6_hdr(skb);
 629
 630         skb_pull(skb, ((hdr->hdrlen + 1) << 3));
 631         skb_postpull_rcsum(skb, oldhdr,
 632                            sizeof(struct ipv6hdr) + ((hdr->hdrlen + 1) << 3));
 633         skb_push(skb, ((chdr->hdrlen + 1) << 3) + sizeof(struct ipv6hdr));
 634         skb_reset_network_header(skb);
 635         skb_mac_header_rebuild(skb);
 636         skb_set_transport_header(skb, sizeof(struct ipv6hdr));
 637
 638         memmove(ipv6_hdr(skb), oldhdr, sizeof(struct ipv6hdr));
 639         memcpy(skb_transport_header(skb), chdr, (chdr->hdrlen + 1) << 3);
 640
 641         ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 642         skb_postpush_rcsum(skb, ipv6_hdr(skb),
 643                            sizeof(struct ipv6hdr) + ((chdr->hdrlen + 1) << 3));
 644
 645         kfree(buf);
 646
 647         skb_dst_drop(skb);
 648
 649         ip6_route_input(skb);
 650
 651         if (skb_dst(skb)->error) {
 652                 dst_input(skb);
 653                 return -1;
 654         }
 655
 656         if (skb_dst(skb)->dev->flags & IFF_LOOPBACK) {
 657                 if (ipv6_hdr(skb)->hop_limit <= 1) {
 658                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 659                         icmpv6_send(skb, ICMPV6_TIME_EXCEED,
 660                                     ICMPV6_EXC_HOPLIMIT, 0);
 661                         kfree_skb(skb);
 662                         return -1;
 663                 }
 664                 ipv6_hdr(skb)->hop_limit--;
 665
 666                 skb_pull(skb, sizeof(struct ipv6hdr));
 667                 goto looped_back;
 668         }
 669
 670         dst_input(skb);
 671
 672         return -1;
 673 }
 674
 675 /********************************
 676   Routing header.
 677  ********************************/
 678
 679 /* called with rcu_read_lock() */
 680 static int ipv6_rthdr_rcv(struct sk_buff *skb)
 681 {
 682         struct inet6_dev *idev = __in6_dev_get(skb->dev);
 683         struct inet6_skb_parm *opt = IP6CB(skb);
 684         struct in6_addr *addr = NULL;
 685         struct in6_addr daddr;
 686         int n, i;
 687         struct ipv6_rt_hdr *hdr;
 688         struct rt0_hdr *rthdr;
 689         struct net *net = dev_net(skb->dev);
 690         int accept_source_route = net->ipv6.devconf_all->accept_source_route;
 691
 692         if (idev && accept_source_route > idev->cnf.accept_source_route)
 693                 accept_source_route = idev->cnf.accept_source_route;
 694
 695         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 696             !pskb_may_pull(skb, (skb_transport_offset(skb) +
 697                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 698                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 699                 kfree_skb(skb);
 700                 return -1;
 701         }
 702
 703         hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 704
 705         if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ||
 706             skb->pkt_type != PACKET_HOST) {
 707                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 708                 kfree_skb(skb);
 709                 return -1;
 710         }
 711
 712         switch (hdr->type) {
 713         case IPV6_SRCRT_TYPE_4:
 714                 /* segment routing */
 715                 return ipv6_srh_rcv(skb);
 716         case IPV6_SRCRT_TYPE_3:
 717                 /* rpl segment routing */
 718                 return ipv6_rpl_srh_rcv(skb);
 719         default:
 720                 break;
 721         }
 722
 723 looped_back:
 724         if (hdr->segments_left == 0) {
 725                 switch (hdr->type) {
 726 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 727                 case IPV6_SRCRT_TYPE_2:
 728                         /* Silently discard type 2 header unless it was
 729                          * processed by own
 730                          */
 731                         if (!addr) {
 732                                 __IP6_INC_STATS(net, idev,
 733                                                 IPSTATS_MIB_INADDRERRORS);
 734                                 kfree_skb(skb);
 735                                 return -1;
 736                         }
 737                         break;
 738 #endif
 739                 default:
 740                         break;
 741                 }
 742
 743                 opt->lastopt = opt->srcrt = skb_network_header_len(skb);
 744                 skb->transport_header += (hdr->hdrlen + 1) << 3;
 745                 opt->dst0 = opt->dst1;
 746                 opt->dst1 = 0;
 747                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
 748                 return 1;
 749         }
 750
 751         switch (hdr->type) {
 752 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 753         case IPV6_SRCRT_TYPE_2:
 754                 if (accept_source_route < 0)
 755                         goto unknown_rh;
 756                 /* Silently discard invalid RTH type 2 */
 757                 if (hdr->hdrlen != 2 || hdr->segments_left != 1) {
 758                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 759                         kfree_skb(skb);
 760                         return -1;
 761                 }
 762                 break;
 763 #endif
 764         default:
 765                 goto unknown_rh;
 766         }
 767
 768         /*
 769          *      This is the routing header forwarding algorithm from
 770          *      RFC 2460, page 16.
 771          */
 772
 773         n = hdr->hdrlen >> 1;
 774
 775         if (hdr->segments_left > n) {
 776                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 777                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 778                                   ((&hdr->segments_left) -
 779                                    skb_network_header(skb)));
 780                 return -1;
 781         }
 782
 783         /* We are about to mangle packet header. Be careful!
 784            Do not damage packets queued somewhere.
 785          */
 786         if (skb_cloned(skb)) {
 787                 /* the copy is a forwarded packet */
 788                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
 789                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 790                                         IPSTATS_MIB_OUTDISCARDS);
 791                         kfree_skb(skb);
 792                         return -1;
 793                 }
 794                 hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 795         }
 796
 797         if (skb->ip_summed == CHECKSUM_COMPLETE)
 798                 skb->ip_summed = CHECKSUM_NONE;
 799
 800         i = n - --hdr->segments_left;
 801
 802         rthdr = (struct rt0_hdr *) hdr;
 803         addr = rthdr->addr;
 804         addr += i - 1;
 805
 806         switch (hdr->type) {
 807 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 808         case IPV6_SRCRT_TYPE_2:
 809                 if (xfrm6_input_addr(skb, (xfrm_address_t *)addr,
 810                                      (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 811                                      IPPROTO_ROUTING) < 0) {
 812                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 813                         kfree_skb(skb);
 814                         return -1;
 815                 }
 816                 if (!ipv6_chk_home_addr(dev_net(skb_dst(skb)->dev), addr)) {
 817                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 818                         kfree_skb(skb);
 819                         return -1;
 820                 }
 821                 break;
 822 #endif
 823         default:
 824                 break;
 825         }
 826
 827         if (ipv6_addr_is_multicast(addr)) {
 828                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 829                 kfree_skb(skb);
 830                 return -1;
 831         }
 832
 833         daddr = *addr;
 834         *addr = ipv6_hdr(skb)->daddr;
 835         ipv6_hdr(skb)->daddr = daddr;
 836
 837         skb_dst_drop(skb);
 838         ip6_route_input(skb);
 839         if (skb_dst(skb)->error) {
 840                 skb_push(skb, skb->data - skb_network_header(skb));
 841                 dst_input(skb);
 842                 return -1;
 843         }
 844
 845         if (skb_dst(skb)->dev->flags&IFF_LOOPBACK) {
 846                 if (ipv6_hdr(skb)->hop_limit <= 1) {
 847                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 848                         icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
 849                                     0);
 850                         kfree_skb(skb);
 851                         return -1;
 852                 }
 853                 ipv6_hdr(skb)->hop_limit--;
 854                 goto looped_back;
 855         }
 856
 857         skb_push(skb, skb->data - skb_network_header(skb));
 858         dst_input(skb);
 859         return -1;
 860
 861 unknown_rh:
 862         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 863         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 864                           (&hdr->type) - skb_network_header(skb));
 865         return -1;
 866 }
 867
 868 static const struct inet6_protocol rthdr_protocol = {
 869         .handler        =       ipv6_rthdr_rcv,
 870         .flags          =       INET6_PROTO_NOPOLICY,
 871 };
 872
 873 static const struct inet6_protocol destopt_protocol = {
 874         .handler        =       ipv6_destopt_rcv,
 875         .flags          =       INET6_PROTO_NOPOLICY,
 876 };
 877
 878 static const struct inet6_protocol nodata_protocol = {
 879         .handler        =       dst_discard,
 880         .flags          =       INET6_PROTO_NOPOLICY,
 881 };
 882
 883 int __init ipv6_exthdrs_init(void)
 884 {
 885         int ret;
 886
 887         ret = inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 888         if (ret)
 889                 goto out;
 890
 891         ret = inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 892         if (ret)
 893                 goto out_rthdr;
 894
 895         ret = inet6_add_protocol(&nodata_protocol, IPPROTO_NONE);
 896         if (ret)
 897                 goto out_destopt;
 898
 899 out:
 900         return ret;
 901 out_destopt:
 902         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 903 out_rthdr:
 904         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 905         goto out;
 906 };
 907
 908 void ipv6_exthdrs_exit(void)
 909 {
 910         inet6_del_protocol(&nodata_protocol, IPPROTO_NONE);
 911         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 912         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 913 }
 914
 915 /**********************************
 916   Hop-by-hop options.
 917  **********************************/
 918
 919 /*
 920  * Note: we cannot rely on skb_dst(skb) before we assign it in ip6_route_input().
 921  */
 922 static inline struct net *ipv6_skb_net(struct sk_buff *skb)
 923 {
 924         return skb_dst(skb) ? dev_net(skb_dst(skb)->dev) : dev_net(skb->dev);
 925 }
 926
 927 /* Router Alert as of RFC 2711 */
 928
 929 static bool ipv6_hop_ra(struct sk_buff *skb, int optoff)
 930 {
 931         const unsigned char *nh = skb_network_header(skb);
 932
 933         if (nh[optoff + 1] == 2) {
 934                 IP6CB(skb)->flags |= IP6SKB_ROUTERALERT;
 935                 memcpy(&IP6CB(skb)->ra, nh + optoff + 2, sizeof(IP6CB(skb)->ra));
 936                 return true;
 937         }
 938         net_dbg_ratelimited("ipv6_hop_ra: wrong RA length %d\n",
 939                             nh[optoff + 1]);
 940         kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR);
 941         return false;
 942 }
 943
 944 /* IOAM */
 945
 946 static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff)
 947 {
 948         struct ioam6_trace_hdr *trace;
 949         struct ioam6_namespace *ns;
 950         struct ioam6_hdr *hdr;
 951
 952         /* Bad alignment (must be 4n-aligned) */
 953         if (optoff & 3)
 954                 goto drop;
 955
 956         /* Ignore if IOAM is not enabled on ingress */
 957         if (!__in6_dev_get(skb->dev)->cnf.ioam6_enabled)
 958                 goto ignore;
 959
 960         /* Truncated Option header */
 961         hdr = (struct ioam6_hdr *)(skb_network_header(skb) + optoff);
 962         if (hdr->opt_len < 2)
 963                 goto drop;
 964
 965         switch (hdr->type) {
 966         case IOAM6_TYPE_PREALLOC:
 967                 /* Truncated Pre-allocated Trace header */
 968                 if (hdr->opt_len < 2 + sizeof(*trace))
 969                         goto drop;
 970
 971                 /* Malformed Pre-allocated Trace header */
 972                 trace = (struct ioam6_trace_hdr *)((u8 *)hdr + sizeof(*hdr));
 973                 if (hdr->opt_len < 2 + sizeof(*trace) + trace->remlen * 4)
 974                         goto drop;
 975
 976                 /* Ignore if the IOAM namespace is unknown */
 977                 ns = ioam6_namespace(ipv6_skb_net(skb), trace->namespace_id);
 978                 if (!ns)
 979                         goto ignore;
 980
 981                 if (!skb_valid_dst(skb))
 982                         ip6_route_input(skb);
 983
 984                 ioam6_fill_trace_data(skb, ns, trace, true);
 985                 break;
 986         default:
 987                 break;
 988         }
 989
 990 ignore:
 991         return true;
 992
 993 drop:
 994         kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR);
 995         return false;
 996 }
 997
 998 /* Jumbo payload */
 999
1000 static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
1001 {
1002         const unsigned char *nh = skb_network_header(skb);
1003         SKB_DR(reason);
1004         u32 pkt_len;
1005
1006         if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
1007                 net_dbg_ratelimited("ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
1008                                     nh[optoff+1]);
1009                 SKB_DR_SET(reason, IP_INHDR);
1010                 goto drop;
1011         }
1012
1013         pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
1014         if (pkt_len <= IPV6_MAXPLEN) {
1015                 icmpv6_param_prob_reason(skb, ICMPV6_HDR_FIELD, optoff + 2,
1016                                          SKB_DROP_REASON_IP_INHDR);
1017                 return false;
1018         }
1019         if (ipv6_hdr(skb)->payload_len) {
1020                 icmpv6_param_prob_reason(skb, ICMPV6_HDR_FIELD, optoff,
1021                                          SKB_DROP_REASON_IP_INHDR);
1022                 return false;
1023         }
1024
1025         if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
1026                 SKB_DR_SET(reason, PKT_TOO_SMALL);
1027                 goto drop;
1028         }
1029
1030         if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
1031                 goto drop;
1032
1033         IP6CB(skb)->flags |= IP6SKB_JUMBOGRAM;
1034         return true;
1035
1036 drop:
1037         kfree_skb_reason(skb, reason);
1038         return false;
1039 }
1040
1041 /* CALIPSO RFC 5570 */
1042
1043 static bool ipv6_hop_calipso(struct sk_buff *skb, int optoff)
1044 {
1045         const unsigned char *nh = skb_network_header(skb);
1046
1047         if (nh[optoff + 1] < 8)
1048                 goto drop;
1049
1050         if (nh[optoff + 6] * 4 + 8 > nh[optoff + 1])
1051                 goto drop;
1052
1053         if (!calipso_validate(skb, nh + optoff))
1054                 goto drop;
1055
1056         return true;
1057
1058 drop:
1059         kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR);
1060         return false;
1061 }
1062
1063 int ipv6_parse_hopopts(struct sk_buff *skb)
1064 {
1065         struct inet6_skb_parm *opt = IP6CB(skb);
1066         struct net *net = dev_net(skb->dev);
1067         int extlen;
1068
1069         /*
1070          * skb_network_header(skb) is equal to skb->data, and
1071          * skb_network_header_len(skb) is always equal to
1072          * sizeof(struct ipv6hdr) by definition of
1073          * hop-by-hop options.
1074          */
1075         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
1076             !pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
1077                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
1078 fail_and_free:
1079                 kfree_skb(skb);
1080                 return -1;
1081         }
1082
1083         extlen = (skb_transport_header(skb)[1] + 1) << 3;
1084         if (extlen > net->ipv6.sysctl.max_hbh_opts_len)
1085                 goto fail_and_free;
1086
1087         opt->flags |= IP6SKB_HOPBYHOP;
1088         if (ip6_parse_tlv(true, skb, net->ipv6.sysctl.max_hbh_opts_cnt)) {
1089                 skb->transport_header += extlen;
1090                 opt = IP6CB(skb);
1091                 opt->nhoff = sizeof(struct ipv6hdr);
1092                 return 1;
1093         }
1094         return -1;
1095 }
1096
1097 /*
1098  *      Creating outbound headers.
1099  *
1100  *      "build" functions work when skb is filled from head to tail (datagram)
1101  *      "push"  functions work when headers are added from tail to head (tcp)
1102  *
1103  *      In both cases we assume, that caller reserved enough room
1104  *      for headers.
1105  */
1106
1107 static void ipv6_push_rthdr0(struct sk_buff *skb, u8 *proto,
1108                              struct ipv6_rt_hdr *opt,
1109                              struct in6_addr **addr_p, struct in6_addr *saddr)
1110 {
1111         struct rt0_hdr *phdr, *ihdr;
1112         int hops;
1113
1114         ihdr = (struct rt0_hdr *) opt;
1115
1116         phdr = skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
1117         memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
1118
1119         hops = ihdr->rt_hdr.hdrlen >> 1;
1120
1121         if (hops > 1)
1122                 memcpy(phdr->addr, ihdr->addr + 1,
1123                        (hops - 1) * sizeof(struct in6_addr));
1124
1125         phdr->addr[hops - 1] = **addr_p;
1126         *addr_p = ihdr->addr;
1127
1128         phdr->rt_hdr.nexthdr = *proto;
1129         *proto = NEXTHDR_ROUTING;
1130 }
1131
1132 static void ipv6_push_rthdr4(struct sk_buff *skb, u8 *proto,
1133                              struct ipv6_rt_hdr *opt,
1134                              struct in6_addr **addr_p, struct in6_addr *saddr)
1135 {
1136         struct ipv6_sr_hdr *sr_phdr, *sr_ihdr;
1137         int plen, hops;
1138
1139         sr_ihdr = (struct ipv6_sr_hdr *)opt;
1140         plen = (sr_ihdr->hdrlen + 1) << 3;
1141
1142         sr_phdr = skb_push(skb, plen);
1143         memcpy(sr_phdr, sr_ihdr, sizeof(struct ipv6_sr_hdr));
1144
1145         hops = sr_ihdr->first_segment + 1;
1146         memcpy(sr_phdr->segments + 1, sr_ihdr->segments + 1,
1147                (hops - 1) * sizeof(struct in6_addr));
1148
1149         sr_phdr->segments[0] = **addr_p;
1150         *addr_p = &sr_ihdr->segments[sr_ihdr->segments_left];
1151
1152         if (sr_ihdr->hdrlen > hops * 2) {
1153                 int tlvs_offset, tlvs_length;
1154
1155                 tlvs_offset = (1 + hops * 2) << 3;
1156                 tlvs_length = (sr_ihdr->hdrlen - hops * 2) << 3;
1157                 memcpy((char *)sr_phdr + tlvs_offset,
1158                        (char *)sr_ihdr + tlvs_offset, tlvs_length);
1159         }
1160
1161 #ifdef CONFIG_IPV6_SEG6_HMAC
1162         if (sr_has_hmac(sr_phdr)) {
1163                 struct net *net = NULL;
1164
1165                 if (skb->dev)
1166                         net = dev_net(skb->dev);
1167                 else if (skb->sk)
1168                         net = sock_net(skb->sk);
1169
1170                 WARN_ON(!net);
1171
1172                 if (net)
1173                         seg6_push_hmac(net, saddr, sr_phdr);
1174         }
1175 #endif
1176
1177         sr_phdr->nexthdr = *proto;
1178         *proto = NEXTHDR_ROUTING;
1179 }
1180
1181 static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
1182                             struct ipv6_rt_hdr *opt,
1183                             struct in6_addr **addr_p, struct in6_addr *saddr)
1184 {
1185         switch (opt->type) {
1186         case IPV6_SRCRT_TYPE_0:
1187         case IPV6_SRCRT_STRICT:
1188         case IPV6_SRCRT_TYPE_2:
1189                 ipv6_push_rthdr0(skb, proto, opt, addr_p, saddr);
1190                 break;
1191         case IPV6_SRCRT_TYPE_4:
1192                 ipv6_push_rthdr4(skb, proto, opt, addr_p, saddr);
1193                 break;
1194         default:
1195                 break;
1196         }
1197 }
1198
1199 static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
1200 {
1201         struct ipv6_opt_hdr *h = skb_push(skb, ipv6_optlen(opt));
1202
1203         memcpy(h, opt, ipv6_optlen(opt));
1204         h->nexthdr = *proto;
1205         *proto = type;
1206 }
1207
1208 void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
1209                           u8 *proto,
1210                           struct in6_addr **daddr, struct in6_addr *saddr)
1211 {
1212         if (opt->srcrt) {
1213                 ipv6_push_rthdr(skb, proto, opt->srcrt, daddr, saddr);
1214                 /*
1215                  * IPV6_RTHDRDSTOPTS is ignored
1216                  * unless IPV6_RTHDR is set (RFC3542).
1217                  */
1218                 if (opt->dst0opt)
1219                         ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
1220         }
1221         if (opt->hopopt)
1222                 ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
1223 }
1224
1225 void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
1226 {
1227         if (opt->dst1opt)
1228                 ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
1229 }
1230 EXPORT_SYMBOL(ipv6_push_frag_opts);
1231
1232 struct ipv6_txoptions *
1233 ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
1234 {
1235         struct ipv6_txoptions *opt2;
1236
1237         opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
1238         if (opt2) {
1239                 long dif = (char *)opt2 - (char *)opt;
1240                 memcpy(opt2, opt, opt->tot_len);
1241                 if (opt2->hopopt)
1242                         *((char **)&opt2->hopopt) += dif;
1243                 if (opt2->dst0opt)
1244                         *((char **)&opt2->dst0opt) += dif;
1245                 if (opt2->dst1opt)
1246                         *((char **)&opt2->dst1opt) += dif;
1247                 if (opt2->srcrt)
1248                         *((char **)&opt2->srcrt) += dif;
1249                 refcount_set(&opt2->refcnt, 1);
1250         }
1251         return opt2;
1252 }
1253 EXPORT_SYMBOL_GPL(ipv6_dup_options);
1254
1255 static void ipv6_renew_option(int renewtype,
1256                               struct ipv6_opt_hdr **dest,
1257                               struct ipv6_opt_hdr *old,
1258                               struct ipv6_opt_hdr *new,
1259                               int newtype, char **p)
1260 {
1261         struct ipv6_opt_hdr *src;
1262
1263         src = (renewtype == newtype ? new : old);
1264         if (!src)
1265                 return;
1266
1267         memcpy(*p, src, ipv6_optlen(src));
1268         *dest = (struct ipv6_opt_hdr *)*p;
1269         *p += CMSG_ALIGN(ipv6_optlen(*dest));
1270 }
1271
1272 /**
1273  * ipv6_renew_options - replace a specific ext hdr with a new one.
1274  *
1275  * @sk: sock from which to allocate memory
1276  * @opt: original options
1277  * @newtype: option type to replace in @opt
1278  * @newopt: new option of type @newtype to replace (user-mem)
1279  *
1280  * Returns a new set of options which is a copy of @opt with the
1281  * option type @newtype replaced with @newopt.
1282  *
1283  * @opt may be NULL, in which case a new set of options is returned
1284  * containing just @newopt.
1285  *
1286  * @newopt may be NULL, in which case the specified option type is
1287  * not copied into the new set of options.
1288  *
1289  * The new set of options is allocated from the socket option memory
1290  * buffer of @sk.
1291  */
1292 struct ipv6_txoptions *
1293 ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
1294                    int newtype, struct ipv6_opt_hdr *newopt)
1295 {
1296         int tot_len = 0;
1297         char *p;
1298         struct ipv6_txoptions *opt2;
1299
1300         if (opt) {
1301                 if (newtype != IPV6_HOPOPTS && opt->hopopt)
1302                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
1303                 if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
1304                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
1305                 if (newtype != IPV6_RTHDR && opt->srcrt)
1306                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
1307                 if (newtype != IPV6_DSTOPTS && opt->dst1opt)
1308                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
1309         }
1310
1311         if (newopt)
1312                 tot_len += CMSG_ALIGN(ipv6_optlen(newopt));
1313
1314         if (!tot_len)
1315                 return NULL;
1316
1317         tot_len += sizeof(*opt2);
1318         opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
1319         if (!opt2)
1320                 return ERR_PTR(-ENOBUFS);
1321
1322         memset(opt2, 0, tot_len);
1323         refcount_set(&opt2->refcnt, 1);
1324         opt2->tot_len = tot_len;
1325         p = (char *)(opt2 + 1);
1326
1327         ipv6_renew_option(IPV6_HOPOPTS, &opt2->hopopt,
1328                           (opt ? opt->hopopt : NULL),
1329                           newopt, newtype, &p);
1330         ipv6_renew_option(IPV6_RTHDRDSTOPTS, &opt2->dst0opt,
1331                           (opt ? opt->dst0opt : NULL),
1332                           newopt, newtype, &p);
1333         ipv6_renew_option(IPV6_RTHDR,
1334                           (struct ipv6_opt_hdr **)&opt2->srcrt,
1335                           (opt ? (struct ipv6_opt_hdr *)opt->srcrt : NULL),
1336                           newopt, newtype, &p);
1337         ipv6_renew_option(IPV6_DSTOPTS, &opt2->dst1opt,
1338                           (opt ? opt->dst1opt : NULL),
1339                           newopt, newtype, &p);
1340
1341         opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
1342                           (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
1343                           (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
1344         opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
1345
1346         return opt2;
1347 }
1348
1349 struct ipv6_txoptions *__ipv6_fixup_options(struct ipv6_txoptions *opt_space,
1350                                             struct ipv6_txoptions *opt)
1351 {
1352         /*
1353          * ignore the dest before srcrt unless srcrt is being included.
1354          * --yoshfuji
1355          */
1356         if (opt->dst0opt && !opt->srcrt) {
1357                 if (opt_space != opt) {
1358                         memcpy(opt_space, opt, sizeof(*opt_space));
1359                         opt = opt_space;
1360                 }
1361                 opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
1362                 opt->dst0opt = NULL;
1363         }
1364
1365         return opt;
1366 }
1367 EXPORT_SYMBOL_GPL(__ipv6_fixup_options);
1368
1369 /**
1370  * fl6_update_dst - update flowi destination address with info given
1371  *                  by srcrt option, if any.
1372  *
1373  * @fl6: flowi6 for which daddr is to be updated
1374  * @opt: struct ipv6_txoptions in which to look for srcrt opt
1375  * @orig: copy of original daddr address if modified
1376  *
1377  * Returns NULL if no txoptions or no srcrt, otherwise returns orig
1378  * and initial value of fl6->daddr set in orig
1379  */
1380 struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
1381                                 const struct ipv6_txoptions *opt,
1382                                 struct in6_addr *orig)
1383 {
1384         if (!opt || !opt->srcrt)
1385                 return NULL;
1386
1387         *orig = fl6->daddr;
1388
1389         switch (opt->srcrt->type) {
1390         case IPV6_SRCRT_TYPE_0:
1391         case IPV6_SRCRT_STRICT:
1392         case IPV6_SRCRT_TYPE_2:
1393                 fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr;
1394                 break;
1395         case IPV6_SRCRT_TYPE_4:
1396         {
1397                 struct ipv6_sr_hdr *srh = (struct ipv6_sr_hdr *)opt->srcrt;
1398
1399                 fl6->daddr = srh->segments[srh->segments_left];
1400                 break;
1401         }
1402         default:
1403                 return NULL;
1404         }
1405
1406         return orig;
1407 }
1408 EXPORT_SYMBOL_GPL(fl6_update_dst);