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 <linux/ioam6_genl.h>
  54 #include <net/ioam6.h>
  55 #include <net/dst_metadata.h>
  56
  57 #include <linux/uaccess.h>
  58
  59 /*********************
  60   Generic functions
  61  *********************/
  62
  63 /* An unknown option is detected, decide what to do */
  64
  65 static bool ip6_tlvopt_unknown(struct sk_buff *skb, int optoff,
  66                                bool disallow_unknowns)
  67 {
  68         if (disallow_unknowns) {
  69                 /* If unknown TLVs are disallowed by configuration
  70                  * then always silently drop packet. Note this also
  71                  * means no ICMP parameter problem is sent which
  72                  * could be a good property to mitigate a reflection DOS
  73                  * attack.
  74                  */
  75
  76                 goto drop;
  77         }
  78
  79         switch ((skb_network_header(skb)[optoff] & 0xC0) >> 6) {
  80         case 0: /* ignore */
  81                 return true;
  82
  83         case 1: /* drop packet */
  84                 break;
  85
  86         case 3: /* Send ICMP if not a multicast address and drop packet */
  87                 /* Actually, it is redundant check. icmp_send
  88                    will recheck in any case.
  89                  */
  90                 if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr))
  91                         break;
  92                 fallthrough;
  93         case 2: /* send ICMP PARM PROB regardless and drop packet */
  94                 icmpv6_param_prob_reason(skb, ICMPV6_UNK_OPTION, optoff,
  95                                          SKB_DROP_REASON_UNHANDLED_PROTO);
  96                 return false;
  97         }
  98
  99 drop:
 100         kfree_skb_reason(skb, SKB_DROP_REASON_UNHANDLED_PROTO);
 101         return false;
 102 }
 103
 104 static bool ipv6_hop_ra(struct sk_buff *skb, int optoff);
 105 static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff);
 106 static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff);
 107 static bool ipv6_hop_calipso(struct sk_buff *skb, int optoff);
 108 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 109 static bool ipv6_dest_hao(struct sk_buff *skb, int optoff);
 110 #endif
 111
 112 /* Parse tlv encoded option header (hop-by-hop or destination) */
 113
 114 static bool ip6_parse_tlv(bool hopbyhop,
 115                           struct sk_buff *skb,
 116                           int max_count)
 117 {
 118         int len = (skb_transport_header(skb)[1] + 1) << 3;
 119         const unsigned char *nh = skb_network_header(skb);
 120         int off = skb_network_header_len(skb);
 121         bool disallow_unknowns = false;
 122         int tlv_count = 0;
 123         int padlen = 0;
 124
 125         if (unlikely(max_count < 0)) {
 126                 disallow_unknowns = true;
 127                 max_count = -max_count;
 128         }
 129
 130         off += 2;
 131         len -= 2;
 132
 133         while (len > 0) {
 134                 int optlen, i;
 135
 136                 if (nh[off] == IPV6_TLV_PAD1) {
 137                         padlen++;
 138                         if (padlen > 7)
 139                                 goto bad;
 140                         off++;
 141                         len--;
 142                         continue;
 143                 }
 144                 if (len < 2)
 145                         goto bad;
 146                 optlen = nh[off + 1] + 2;
 147                 if (optlen > len)
 148                         goto bad;
 149
 150                 if (nh[off] == IPV6_TLV_PADN) {
 151                         /* RFC 2460 states that the purpose of PadN is
 152                          * to align the containing header to multiples
 153                          * of 8. 7 is therefore the highest valid value.
 154                          * See also RFC 4942, Section 2.1.9.5.
 155                          */
 156                         padlen += optlen;
 157                         if (padlen > 7)
 158                                 goto bad;
 159                         /* RFC 4942 recommends receiving hosts to
 160                          * actively check PadN payload to contain
 161                          * only zeroes.
 162                          */
 163                         for (i = 2; i < optlen; i++) {
 164                                 if (nh[off + i] != 0)
 165                                         goto bad;
 166                         }
 167                 } else {
 168                         tlv_count++;
 169                         if (tlv_count > max_count)
 170                                 goto bad;
 171
 172                         if (hopbyhop) {
 173                                 switch (nh[off]) {
 174                                 case IPV6_TLV_ROUTERALERT:
 175                                         if (!ipv6_hop_ra(skb, off))
 176                                                 return false;
 177                                         break;
 178                                 case IPV6_TLV_IOAM:
 179                                         if (!ipv6_hop_ioam(skb, off))
 180                                                 return false;
 181
 182                                         nh = skb_network_header(skb);
 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 = min(READ_ONCE(net->ipv6.devconf_all->seg6_enabled),
 383                           READ_ONCE(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;
 658
 659         accept_source_route = READ_ONCE(net->ipv6.devconf_all->accept_source_route);
 660
 661         if (idev)
 662                 accept_source_route = min(accept_source_route,
 663                                           READ_ONCE(idev->cnf.accept_source_route));
 664
 665         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 666             !pskb_may_pull(skb, (skb_transport_offset(skb) +
 667                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
 668                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 669                 kfree_skb(skb);
 670                 return -1;
 671         }
 672
 673         hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 674
 675         if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ||
 676             skb->pkt_type != PACKET_HOST) {
 677                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 678                 kfree_skb(skb);
 679                 return -1;
 680         }
 681
 682         switch (hdr->type) {
 683         case IPV6_SRCRT_TYPE_4:
 684                 /* segment routing */
 685                 return ipv6_srh_rcv(skb);
 686         case IPV6_SRCRT_TYPE_3:
 687                 /* rpl segment routing */
 688                 return ipv6_rpl_srh_rcv(skb);
 689         default:
 690                 break;
 691         }
 692
 693 looped_back:
 694         if (hdr->segments_left == 0) {
 695                 switch (hdr->type) {
 696 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 697                 case IPV6_SRCRT_TYPE_2:
 698                         /* Silently discard type 2 header unless it was
 699                          * processed by own
 700                          */
 701                         if (!addr) {
 702                                 __IP6_INC_STATS(net, idev,
 703                                                 IPSTATS_MIB_INADDRERRORS);
 704                                 kfree_skb(skb);
 705                                 return -1;
 706                         }
 707                         break;
 708 #endif
 709                 default:
 710                         break;
 711                 }
 712
 713                 opt->lastopt = opt->srcrt = skb_network_header_len(skb);
 714                 skb->transport_header += (hdr->hdrlen + 1) << 3;
 715                 opt->dst0 = opt->dst1;
 716                 opt->dst1 = 0;
 717                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
 718                 return 1;
 719         }
 720
 721         switch (hdr->type) {
 722 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 723         case IPV6_SRCRT_TYPE_2:
 724                 if (accept_source_route < 0)
 725                         goto unknown_rh;
 726                 /* Silently discard invalid RTH type 2 */
 727                 if (hdr->hdrlen != 2 || hdr->segments_left != 1) {
 728                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 729                         kfree_skb(skb);
 730                         return -1;
 731                 }
 732                 break;
 733 #endif
 734         default:
 735                 goto unknown_rh;
 736         }
 737
 738         /*
 739          *      This is the routing header forwarding algorithm from
 740          *      RFC 2460, page 16.
 741          */
 742
 743         n = hdr->hdrlen >> 1;
 744
 745         if (hdr->segments_left > n) {
 746                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 747                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 748                                   ((&hdr->segments_left) -
 749                                    skb_network_header(skb)));
 750                 return -1;
 751         }
 752
 753         /* We are about to mangle packet header. Be careful!
 754            Do not damage packets queued somewhere.
 755          */
 756         if (skb_cloned(skb)) {
 757                 /* the copy is a forwarded packet */
 758                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
 759                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 760                                         IPSTATS_MIB_OUTDISCARDS);
 761                         kfree_skb(skb);
 762                         return -1;
 763                 }
 764                 hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
 765         }
 766
 767         if (skb->ip_summed == CHECKSUM_COMPLETE)
 768                 skb->ip_summed = CHECKSUM_NONE;
 769
 770         i = n - --hdr->segments_left;
 771
 772         rthdr = (struct rt0_hdr *) hdr;
 773         addr = rthdr->addr;
 774         addr += i - 1;
 775
 776         switch (hdr->type) {
 777 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 778         case IPV6_SRCRT_TYPE_2:
 779                 if (xfrm6_input_addr(skb, (xfrm_address_t *)addr,
 780                                      (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 781                                      IPPROTO_ROUTING) < 0) {
 782                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 783                         kfree_skb(skb);
 784                         return -1;
 785                 }
 786                 if (!ipv6_chk_home_addr(dev_net(skb_dst(skb)->dev), addr)) {
 787                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 788                         kfree_skb(skb);
 789                         return -1;
 790                 }
 791                 break;
 792 #endif
 793         default:
 794                 break;
 795         }
 796
 797         if (ipv6_addr_is_multicast(addr)) {
 798                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 799                 kfree_skb(skb);
 800                 return -1;
 801         }
 802
 803         swap(*addr, ipv6_hdr(skb)->daddr);
 804
 805         ip6_route_input(skb);
 806         if (skb_dst(skb)->error) {
 807                 skb_push(skb, -skb_network_offset(skb));
 808                 dst_input(skb);
 809                 return -1;
 810         }
 811
 812         if (skb_dst(skb)->dev->flags&IFF_LOOPBACK) {
 813                 if (ipv6_hdr(skb)->hop_limit <= 1) {
 814                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 815                         icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
 816                                     0);
 817                         kfree_skb(skb);
 818                         return -1;
 819                 }
 820                 ipv6_hdr(skb)->hop_limit--;
 821                 goto looped_back;
 822         }
 823
 824         skb_push(skb, -skb_network_offset(skb));
 825         dst_input(skb);
 826         return -1;
 827
 828 unknown_rh:
 829         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 830         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 831                           (&hdr->type) - skb_network_header(skb));
 832         return -1;
 833 }
 834
 835 static const struct inet6_protocol rthdr_protocol = {
 836         .handler        =       ipv6_rthdr_rcv,
 837         .flags          =       INET6_PROTO_NOPOLICY,
 838 };
 839
 840 static const struct inet6_protocol destopt_protocol = {
 841         .handler        =       ipv6_destopt_rcv,
 842         .flags          =       INET6_PROTO_NOPOLICY,
 843 };
 844
 845 static const struct inet6_protocol nodata_protocol = {
 846         .handler        =       dst_discard,
 847         .flags          =       INET6_PROTO_NOPOLICY,
 848 };
 849
 850 int __init ipv6_exthdrs_init(void)
 851 {
 852         int ret;
 853
 854         ret = inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 855         if (ret)
 856                 goto out;
 857
 858         ret = inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 859         if (ret)
 860                 goto out_rthdr;
 861
 862         ret = inet6_add_protocol(&nodata_protocol, IPPROTO_NONE);
 863         if (ret)
 864                 goto out_destopt;
 865
 866 out:
 867         return ret;
 868 out_destopt:
 869         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 870 out_rthdr:
 871         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 872         goto out;
 873 };
 874
 875 void ipv6_exthdrs_exit(void)
 876 {
 877         inet6_del_protocol(&nodata_protocol, IPPROTO_NONE);
 878         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
 879         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
 880 }
 881
 882 /**********************************
 883   Hop-by-hop options.
 884  **********************************/
 885
 886 /* Router Alert as of RFC 2711 */
 887
 888 static bool ipv6_hop_ra(struct sk_buff *skb, int optoff)
 889 {
 890         const unsigned char *nh = skb_network_header(skb);
 891
 892         if (nh[optoff + 1] == 2) {
 893                 IP6CB(skb)->flags |= IP6SKB_ROUTERALERT;
 894                 memcpy(&IP6CB(skb)->ra, nh + optoff + 2, sizeof(IP6CB(skb)->ra));
 895                 return true;
 896         }
 897         net_dbg_ratelimited("ipv6_hop_ra: wrong RA length %d\n",
 898                             nh[optoff + 1]);
 899         kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR);
 900         return false;
 901 }
 902
 903 /* IOAM */
 904
 905 static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff)
 906 {
 907         struct ioam6_trace_hdr *trace;
 908         struct ioam6_namespace *ns;
 909         struct ioam6_hdr *hdr;
 910
 911         /* Bad alignment (must be 4n-aligned) */
 912         if (optoff & 3)
 913                 goto drop;
 914
 915         /* Ignore if IOAM is not enabled on ingress */
 916         if (!READ_ONCE(__in6_dev_get(skb->dev)->cnf.ioam6_enabled))
 917                 goto ignore;
 918
 919         /* Truncated Option header */
 920         hdr = (struct ioam6_hdr *)(skb_network_header(skb) + optoff);
 921         if (hdr->opt_len < 2)
 922                 goto drop;
 923
 924         switch (hdr->type) {
 925         case IOAM6_TYPE_PREALLOC:
 926                 /* Truncated Pre-allocated Trace header */
 927                 if (hdr->opt_len < 2 + sizeof(*trace))
 928                         goto drop;
 929
 930                 /* Malformed Pre-allocated Trace header */
 931                 trace = (struct ioam6_trace_hdr *)((u8 *)hdr + sizeof(*hdr));
 932                 if (hdr->opt_len < 2 + sizeof(*trace) + trace->remlen * 4)
 933                         goto drop;
 934
 935                 /* Ignore if the IOAM namespace is unknown */
 936                 ns = ioam6_namespace(dev_net(skb->dev), trace->namespace_id);
 937                 if (!ns)
 938                         goto ignore;
 939
 940                 if (!skb_valid_dst(skb))
 941                         ip6_route_input(skb);
 942
 943                 /* About to mangle packet header */
 944                 if (skb_ensure_writable(skb, optoff + 2 + hdr->opt_len))
 945                         goto drop;
 946
 947                 /* Trace pointer may have changed */
 948                 trace = (struct ioam6_trace_hdr *)(skb_network_header(skb)
 949                                                    + optoff + sizeof(*hdr));
 950
 951                 ioam6_fill_trace_data(skb, ns, trace, true);
 952
 953                 ioam6_event(IOAM6_EVENT_TRACE, dev_net(skb->dev),
 954                             GFP_ATOMIC, (void *)trace, hdr->opt_len - 2);
 955                 break;
 956         default:
 957                 break;
 958         }
 959
 960 ignore:
 961         return true;
 962
 963 drop:
 964         kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR);
 965         return false;
 966 }
 967
 968 /* Jumbo payload */
 969
 970 static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
 971 {
 972         const unsigned char *nh = skb_network_header(skb);
 973         SKB_DR(reason);
 974         u32 pkt_len;
 975
 976         if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
 977                 net_dbg_ratelimited("ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
 978                                     nh[optoff+1]);
 979                 SKB_DR_SET(reason, IP_INHDR);
 980                 goto drop;
 981         }
 982
 983         pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
 984         if (pkt_len <= IPV6_MAXPLEN) {
 985                 icmpv6_param_prob_reason(skb, ICMPV6_HDR_FIELD, optoff + 2,
 986                                          SKB_DROP_REASON_IP_INHDR);
 987                 return false;
 988         }
 989         if (ipv6_hdr(skb)->payload_len) {
 990                 icmpv6_param_prob_reason(skb, ICMPV6_HDR_FIELD, optoff,
 991                                          SKB_DROP_REASON_IP_INHDR);
 992                 return false;
 993         }
 994
 995         if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
 996                 SKB_DR_SET(reason, PKT_TOO_SMALL);
 997                 goto drop;
 998         }
 999
1000         if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
1001                 goto drop;
1002
1003         IP6CB(skb)->flags |= IP6SKB_JUMBOGRAM;
1004         return true;
1005
1006 drop:
1007         kfree_skb_reason(skb, reason);
1008         return false;
1009 }
1010
1011 /* CALIPSO RFC 5570 */
1012
1013 static bool ipv6_hop_calipso(struct sk_buff *skb, int optoff)
1014 {
1015         const unsigned char *nh = skb_network_header(skb);
1016
1017         if (nh[optoff + 1] < 8)
1018                 goto drop;
1019
1020         if (nh[optoff + 6] * 4 + 8 > nh[optoff + 1])
1021                 goto drop;
1022
1023         if (!calipso_validate(skb, nh + optoff))
1024                 goto drop;
1025
1026         return true;
1027
1028 drop:
1029         kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR);
1030         return false;
1031 }
1032
1033 int ipv6_parse_hopopts(struct sk_buff *skb)
1034 {
1035         struct inet6_skb_parm *opt = IP6CB(skb);
1036         struct net *net = dev_net(skb->dev);
1037         int extlen;
1038
1039         /*
1040          * skb_network_header(skb) is equal to skb->data, and
1041          * skb_network_header_len(skb) is always equal to
1042          * sizeof(struct ipv6hdr) by definition of
1043          * hop-by-hop options.
1044          */
1045         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
1046             !pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
1047                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
1048 fail_and_free:
1049                 kfree_skb(skb);
1050                 return -1;
1051         }
1052
1053         extlen = (skb_transport_header(skb)[1] + 1) << 3;
1054         if (extlen > net->ipv6.sysctl.max_hbh_opts_len)
1055                 goto fail_and_free;
1056
1057         opt->flags |= IP6SKB_HOPBYHOP;
1058         if (ip6_parse_tlv(true, skb, net->ipv6.sysctl.max_hbh_opts_cnt)) {
1059                 skb->transport_header += extlen;
1060                 opt = IP6CB(skb);
1061                 opt->nhoff = sizeof(struct ipv6hdr);
1062                 return 1;
1063         }
1064         return -1;
1065 }
1066
1067 /*
1068  *      Creating outbound headers.
1069  *
1070  *      "build" functions work when skb is filled from head to tail (datagram)
1071  *      "push"  functions work when headers are added from tail to head (tcp)
1072  *
1073  *      In both cases we assume, that caller reserved enough room
1074  *      for headers.
1075  */
1076
1077 static void ipv6_push_rthdr0(struct sk_buff *skb, u8 *proto,
1078                              struct ipv6_rt_hdr *opt,
1079                              struct in6_addr **addr_p, struct in6_addr *saddr)
1080 {
1081         struct rt0_hdr *phdr, *ihdr;
1082         int hops;
1083
1084         ihdr = (struct rt0_hdr *) opt;
1085
1086         phdr = skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
1087         memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
1088
1089         hops = ihdr->rt_hdr.hdrlen >> 1;
1090
1091         if (hops > 1)
1092                 memcpy(phdr->addr, ihdr->addr + 1,
1093                        (hops - 1) * sizeof(struct in6_addr));
1094
1095         phdr->addr[hops - 1] = **addr_p;
1096         *addr_p = ihdr->addr;
1097
1098         phdr->rt_hdr.nexthdr = *proto;
1099         *proto = NEXTHDR_ROUTING;
1100 }
1101
1102 static void ipv6_push_rthdr4(struct sk_buff *skb, u8 *proto,
1103                              struct ipv6_rt_hdr *opt,
1104                              struct in6_addr **addr_p, struct in6_addr *saddr)
1105 {
1106         struct ipv6_sr_hdr *sr_phdr, *sr_ihdr;
1107         int plen, hops;
1108
1109         sr_ihdr = (struct ipv6_sr_hdr *)opt;
1110         plen = (sr_ihdr->hdrlen + 1) << 3;
1111
1112         sr_phdr = skb_push(skb, plen);
1113         memcpy(sr_phdr, sr_ihdr, sizeof(struct ipv6_sr_hdr));
1114
1115         hops = sr_ihdr->first_segment + 1;
1116         memcpy(sr_phdr->segments + 1, sr_ihdr->segments + 1,
1117                (hops - 1) * sizeof(struct in6_addr));
1118
1119         sr_phdr->segments[0] = **addr_p;
1120         *addr_p = &sr_ihdr->segments[sr_ihdr->segments_left];
1121
1122         if (sr_ihdr->hdrlen > hops * 2) {
1123                 int tlvs_offset, tlvs_length;
1124
1125                 tlvs_offset = (1 + hops * 2) << 3;
1126                 tlvs_length = (sr_ihdr->hdrlen - hops * 2) << 3;
1127                 memcpy((char *)sr_phdr + tlvs_offset,
1128                        (char *)sr_ihdr + tlvs_offset, tlvs_length);
1129         }
1130
1131 #ifdef CONFIG_IPV6_SEG6_HMAC
1132         if (sr_has_hmac(sr_phdr)) {
1133                 struct net *net = NULL;
1134
1135                 if (skb->dev)
1136                         net = dev_net(skb->dev);
1137                 else if (skb->sk)
1138                         net = sock_net(skb->sk);
1139
1140                 WARN_ON(!net);
1141
1142                 if (net)
1143                         seg6_push_hmac(net, saddr, sr_phdr);
1144         }
1145 #endif
1146
1147         sr_phdr->nexthdr = *proto;
1148         *proto = NEXTHDR_ROUTING;
1149 }
1150
1151 static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
1152                             struct ipv6_rt_hdr *opt,
1153                             struct in6_addr **addr_p, struct in6_addr *saddr)
1154 {
1155         switch (opt->type) {
1156         case IPV6_SRCRT_TYPE_0:
1157         case IPV6_SRCRT_STRICT:
1158         case IPV6_SRCRT_TYPE_2:
1159                 ipv6_push_rthdr0(skb, proto, opt, addr_p, saddr);
1160                 break;
1161         case IPV6_SRCRT_TYPE_4:
1162                 ipv6_push_rthdr4(skb, proto, opt, addr_p, saddr);
1163                 break;
1164         default:
1165                 break;
1166         }
1167 }
1168
1169 static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
1170 {
1171         struct ipv6_opt_hdr *h = skb_push(skb, ipv6_optlen(opt));
1172
1173         memcpy(h, opt, ipv6_optlen(opt));
1174         h->nexthdr = *proto;
1175         *proto = type;
1176 }
1177
1178 void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
1179                           u8 *proto,
1180                           struct in6_addr **daddr, struct in6_addr *saddr)
1181 {
1182         if (opt->srcrt) {
1183                 ipv6_push_rthdr(skb, proto, opt->srcrt, daddr, saddr);
1184                 /*
1185                  * IPV6_RTHDRDSTOPTS is ignored
1186                  * unless IPV6_RTHDR is set (RFC3542).
1187                  */
1188                 if (opt->dst0opt)
1189                         ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
1190         }
1191         if (opt->hopopt)
1192                 ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
1193 }
1194
1195 void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
1196 {
1197         if (opt->dst1opt)
1198                 ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
1199 }
1200 EXPORT_SYMBOL(ipv6_push_frag_opts);
1201
1202 struct ipv6_txoptions *
1203 ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
1204 {
1205         struct ipv6_txoptions *opt2;
1206
1207         opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
1208         if (opt2) {
1209                 long dif = (char *)opt2 - (char *)opt;
1210                 memcpy(opt2, opt, opt->tot_len);
1211                 if (opt2->hopopt)
1212                         *((char **)&opt2->hopopt) += dif;
1213                 if (opt2->dst0opt)
1214                         *((char **)&opt2->dst0opt) += dif;
1215                 if (opt2->dst1opt)
1216                         *((char **)&opt2->dst1opt) += dif;
1217                 if (opt2->srcrt)
1218                         *((char **)&opt2->srcrt) += dif;
1219                 refcount_set(&opt2->refcnt, 1);
1220         }
1221         return opt2;
1222 }
1223 EXPORT_SYMBOL_GPL(ipv6_dup_options);
1224
1225 static void ipv6_renew_option(int renewtype,
1226                               struct ipv6_opt_hdr **dest,
1227                               struct ipv6_opt_hdr *old,
1228                               struct ipv6_opt_hdr *new,
1229                               int newtype, char **p)
1230 {
1231         struct ipv6_opt_hdr *src;
1232
1233         src = (renewtype == newtype ? new : old);
1234         if (!src)
1235                 return;
1236
1237         memcpy(*p, src, ipv6_optlen(src));
1238         *dest = (struct ipv6_opt_hdr *)*p;
1239         *p += CMSG_ALIGN(ipv6_optlen(*dest));
1240 }
1241
1242 /**
1243  * ipv6_renew_options - replace a specific ext hdr with a new one.
1244  *
1245  * @sk: sock from which to allocate memory
1246  * @opt: original options
1247  * @newtype: option type to replace in @opt
1248  * @newopt: new option of type @newtype to replace (user-mem)
1249  *
1250  * Returns a new set of options which is a copy of @opt with the
1251  * option type @newtype replaced with @newopt.
1252  *
1253  * @opt may be NULL, in which case a new set of options is returned
1254  * containing just @newopt.
1255  *
1256  * @newopt may be NULL, in which case the specified option type is
1257  * not copied into the new set of options.
1258  *
1259  * The new set of options is allocated from the socket option memory
1260  * buffer of @sk.
1261  */
1262 struct ipv6_txoptions *
1263 ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
1264                    int newtype, struct ipv6_opt_hdr *newopt)
1265 {
1266         int tot_len = 0;
1267         char *p;
1268         struct ipv6_txoptions *opt2;
1269
1270         if (opt) {
1271                 if (newtype != IPV6_HOPOPTS && opt->hopopt)
1272                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
1273                 if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
1274                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
1275                 if (newtype != IPV6_RTHDR && opt->srcrt)
1276                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
1277                 if (newtype != IPV6_DSTOPTS && opt->dst1opt)
1278                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
1279         }
1280
1281         if (newopt)
1282                 tot_len += CMSG_ALIGN(ipv6_optlen(newopt));
1283
1284         if (!tot_len)
1285                 return NULL;
1286
1287         tot_len += sizeof(*opt2);
1288         opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
1289         if (!opt2)
1290                 return ERR_PTR(-ENOBUFS);
1291
1292         memset(opt2, 0, tot_len);
1293         refcount_set(&opt2->refcnt, 1);
1294         opt2->tot_len = tot_len;
1295         p = (char *)(opt2 + 1);
1296
1297         ipv6_renew_option(IPV6_HOPOPTS, &opt2->hopopt,
1298                           (opt ? opt->hopopt : NULL),
1299                           newopt, newtype, &p);
1300         ipv6_renew_option(IPV6_RTHDRDSTOPTS, &opt2->dst0opt,
1301                           (opt ? opt->dst0opt : NULL),
1302                           newopt, newtype, &p);
1303         ipv6_renew_option(IPV6_RTHDR,
1304                           (struct ipv6_opt_hdr **)&opt2->srcrt,
1305                           (opt ? (struct ipv6_opt_hdr *)opt->srcrt : NULL),
1306                           newopt, newtype, &p);
1307         ipv6_renew_option(IPV6_DSTOPTS, &opt2->dst1opt,
1308                           (opt ? opt->dst1opt : NULL),
1309                           newopt, newtype, &p);
1310
1311         opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
1312                           (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
1313                           (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
1314         opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
1315
1316         return opt2;
1317 }
1318
1319 struct ipv6_txoptions *__ipv6_fixup_options(struct ipv6_txoptions *opt_space,
1320                                             struct ipv6_txoptions *opt)
1321 {
1322         /*
1323          * ignore the dest before srcrt unless srcrt is being included.
1324          * --yoshfuji
1325          */
1326         if (opt->dst0opt && !opt->srcrt) {
1327                 if (opt_space != opt) {
1328                         memcpy(opt_space, opt, sizeof(*opt_space));
1329                         opt = opt_space;
1330                 }
1331                 opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
1332                 opt->dst0opt = NULL;
1333         }
1334
1335         return opt;
1336 }
1337 EXPORT_SYMBOL_GPL(__ipv6_fixup_options);
1338
1339 /**
1340  * fl6_update_dst - update flowi destination address with info given
1341  *                  by srcrt option, if any.
1342  *
1343  * @fl6: flowi6 for which daddr is to be updated
1344  * @opt: struct ipv6_txoptions in which to look for srcrt opt
1345  * @orig: copy of original daddr address if modified
1346  *
1347  * Returns NULL if no txoptions or no srcrt, otherwise returns orig
1348  * and initial value of fl6->daddr set in orig
1349  */
1350 struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
1351                                 const struct ipv6_txoptions *opt,
1352                                 struct in6_addr *orig)
1353 {
1354         if (!opt || !opt->srcrt)
1355                 return NULL;
1356
1357         *orig = fl6->daddr;
1358
1359         switch (opt->srcrt->type) {
1360         case IPV6_SRCRT_TYPE_0:
1361         case IPV6_SRCRT_STRICT:
1362         case IPV6_SRCRT_TYPE_2:
1363                 fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr;
1364                 break;
1365         case IPV6_SRCRT_TYPE_4:
1366         {
1367                 struct ipv6_sr_hdr *srh = (struct ipv6_sr_hdr *)opt->srcrt;
1368
1369                 fl6->daddr = srh->segments[srh->segments_left];
1370                 break;
1371         }
1372         default:
1373                 return NULL;
1374         }
1375
1376         return orig;
1377 }
1378 EXPORT_SYMBOL_GPL(fl6_update_dst);