net/ipv6/exthdrs.c

   1 /*
   2  *      Extension Header handling for IPv6
   3  *      Linux INET6 implementation
   4  *
   5  *      Authors:
   6  *      Pedro Roque             <roque@di.fc.ul.pt>
   7  *      Andi Kleen              <ak@muc.de>
   8  *      Alexey Kuznetsov        <kuznet@ms2.inr.ac.ru>
   9  *
  10  *      $Id: exthdrs.c,v 1.13 2001/06/19 15:58:56 davem Exp $
  11  *
  12  *      This program is free software; you can redistribute it and/or
  13  *      modify it under the terms of the GNU General Public License
  14  *      as published by the Free Software Foundation; either version
  15  *      2 of the License, or (at your option) any later version.
  16  */
  17
  18 /* Changes:
  19  *      yoshfuji                : ensure not to overrun while parsing
  20  *                                tlv options.
  21  *      Mitsuru KANDA @USAGI and: Remove ipv6_parse_exthdrs().
  22  *      YOSHIFUJI Hideaki @USAGI  Register inbound extension header
  23  *                                handlers as inet6_protocol{}.
  24  */
  25
  26 #include <linux/errno.h>
  27 #include <linux/types.h>
  28 #include <linux/socket.h>
  29 #include <linux/sockios.h>
  30 #include <linux/sched.h>
  31 #include <linux/net.h>
  32 #include <linux/netdevice.h>
  33 #include <linux/in6.h>
  34 #include <linux/icmpv6.h>
  35
  36 #include <net/sock.h>
  37 #include <net/snmp.h>
  38
  39 #include <net/ipv6.h>
  40 #include <net/protocol.h>
  41 #include <net/transp_v6.h>
  42 #include <net/rawv6.h>
  43 #include <net/ndisc.h>
  44 #include <net/ip6_route.h>
  45 #include <net/addrconf.h>
  46
  47 #include <asm/uaccess.h>
  48
  49 /*
  50  *      Parsing tlv encoded headers.
  51  *
  52  *      Parsing function "func" returns 1, if parsing succeed
  53  *      and 0, if it failed.
  54  *      It MUST NOT touch skb->h.
  55  */
  56
  57 struct tlvtype_proc {
  58         int     type;
  59         int     (*func)(struct sk_buff *skb, int offset);
  60 };
  61
  62 /*********************
  63   Generic functions
  64  *********************/
  65
  66 /* An unknown option is detected, decide what to do */
  67
  68 static int ip6_tlvopt_unknown(struct sk_buff *skb, int optoff)
  69 {
  70         switch ((skb->nh.raw[optoff] & 0xC0) >> 6) {
  71         case 0: /* ignore */
  72                 return 1;
  73
  74         case 1: /* drop packet */
  75                 break;
  76
  77         case 3: /* Send ICMP if not a multicast address and drop packet */
  78                 /* Actually, it is redundant check. icmp_send
  79                    will recheck in any case.
  80                  */
  81                 if (ipv6_addr_is_multicast(&skb->nh.ipv6h->daddr))
  82                         break;
  83         case 2: /* send ICMP PARM PROB regardless and drop packet */
  84                 icmpv6_param_prob(skb, ICMPV6_UNK_OPTION, optoff);
  85                 return 0;
  86         };
  87
  88         kfree_skb(skb);
  89         return 0;
  90 }
  91
  92 /* Parse tlv encoded option header (hop-by-hop or destination) */
  93
  94 static int ip6_parse_tlv(struct tlvtype_proc *procs, struct sk_buff *skb)
  95 {
  96         struct tlvtype_proc *curr;
  97         int off = skb->h.raw - skb->nh.raw;
  98         int len = ((skb->h.raw[1]+1)<<3);
  99
 100         if ((skb->h.raw + len) - skb->data > skb_headlen(skb))
 101                 goto bad;
 102
 103         off += 2;
 104         len -= 2;
 105
 106         while (len > 0) {
 107                 int optlen = skb->nh.raw[off+1]+2;
 108
 109                 switch (skb->nh.raw[off]) {
 110                 case IPV6_TLV_PAD0:
 111                         optlen = 1;
 112                         break;
 113
 114                 case IPV6_TLV_PADN:
 115                         break;
 116
 117                 default: /* Other TLV code so scan list */
 118                         if (optlen > len)
 119                                 goto bad;
 120                         for (curr=procs; curr->type >= 0; curr++) {
 121                                 if (curr->type == skb->nh.raw[off]) {
 122                                         /* type specific length/alignment
 123                                            checks will be performed in the
 124                                            func(). */
 125                                         if (curr->func(skb, off) == 0)
 126                                                 return 0;
 127                                         break;
 128                                 }
 129                         }
 130                         if (curr->type < 0) {
 131                                 if (ip6_tlvopt_unknown(skb, off) == 0)
 132                                         return 0;
 133                         }
 134                         break;
 135                 }
 136                 off += optlen;
 137                 len -= optlen;
 138         }
 139         if (len == 0)
 140                 return 1;
 141 bad:
 142         kfree_skb(skb);
 143         return 0;
 144 }
 145
 146 /*****************************
 147   Destination options header.
 148  *****************************/
 149
 150 static struct tlvtype_proc tlvprocdestopt_lst[] = {
 151         /* No destination options are defined now */
 152         {-1,                    NULL}
 153 };
 154
 155 static int ipv6_destopt_rcv(struct sk_buff **skbp, unsigned int *nhoffp)
 156 {
 157         struct sk_buff *skb = *skbp;
 158         struct inet6_skb_parm *opt = IP6CB(skb);
 159
 160         if (!pskb_may_pull(skb, (skb->h.raw-skb->data)+8) ||
 161             !pskb_may_pull(skb, (skb->h.raw-skb->data)+((skb->h.raw[1]+1)<<3))) {
 162                 IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 163                 kfree_skb(skb);
 164                 return -1;
 165         }
 166
 167         opt->lastopt = skb->h.raw - skb->nh.raw;
 168         opt->dst1 = skb->h.raw - skb->nh.raw;
 169
 170         if (ip6_parse_tlv(tlvprocdestopt_lst, skb)) {
 171                 skb->h.raw += ((skb->h.raw[1]+1)<<3);
 172                 *nhoffp = opt->dst1;
 173                 return 1;
 174         }
 175
 176         IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 177         return -1;
 178 }
 179
 180 static struct inet6_protocol destopt_protocol = {
 181         .handler        =       ipv6_destopt_rcv,
 182         .flags          =       INET6_PROTO_NOPOLICY,
 183 };
 184
 185 void __init ipv6_destopt_init(void)
 186 {
 187         if (inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS) < 0)
 188                 printk(KERN_ERR "ipv6_destopt_init: Could not register protocol\n");
 189 }
 190
 191 /********************************
 192   NONE header. No data in packet.
 193  ********************************/
 194
 195 static int ipv6_nodata_rcv(struct sk_buff **skbp, unsigned int *nhoffp)
 196 {
 197         struct sk_buff *skb = *skbp;
 198
 199         kfree_skb(skb);
 200         return 0;
 201 }
 202
 203 static struct inet6_protocol nodata_protocol = {
 204         .handler        =       ipv6_nodata_rcv,
 205         .flags          =       INET6_PROTO_NOPOLICY,
 206 };
 207
 208 void __init ipv6_nodata_init(void)
 209 {
 210         if (inet6_add_protocol(&nodata_protocol, IPPROTO_NONE) < 0)
 211                 printk(KERN_ERR "ipv6_nodata_init: Could not register protocol\n");
 212 }
 213
 214 /********************************
 215   Routing header.
 216  ********************************/
 217
 218 static int ipv6_rthdr_rcv(struct sk_buff **skbp, unsigned int *nhoffp)
 219 {
 220         struct sk_buff *skb = *skbp;
 221         struct inet6_skb_parm *opt = IP6CB(skb);
 222         struct in6_addr *addr;
 223         struct in6_addr daddr;
 224         int n, i;
 225
 226         struct ipv6_rt_hdr *hdr;
 227         struct rt0_hdr *rthdr;
 228
 229         if (!pskb_may_pull(skb, (skb->h.raw-skb->data)+8) ||
 230             !pskb_may_pull(skb, (skb->h.raw-skb->data)+((skb->h.raw[1]+1)<<3))) {
 231                 IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 232                 kfree_skb(skb);
 233                 return -1;
 234         }
 235
 236         hdr = (struct ipv6_rt_hdr *) skb->h.raw;
 237
 238         if (ipv6_addr_is_multicast(&skb->nh.ipv6h->daddr) ||
 239             skb->pkt_type != PACKET_HOST) {
 240                 IP6_INC_STATS_BH(IPSTATS_MIB_INADDRERRORS);
 241                 kfree_skb(skb);
 242                 return -1;
 243         }
 244
 245 looped_back:
 246         if (hdr->segments_left == 0) {
 247                 opt->lastopt = skb->h.raw - skb->nh.raw;
 248                 opt->srcrt = skb->h.raw - skb->nh.raw;
 249                 skb->h.raw += (hdr->hdrlen + 1) << 3;
 250                 opt->dst0 = opt->dst1;
 251                 opt->dst1 = 0;
 252                 *nhoffp = (&hdr->nexthdr) - skb->nh.raw;
 253                 return 1;
 254         }
 255
 256         if (hdr->type != IPV6_SRCRT_TYPE_0) {
 257                 IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 258                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, (&hdr->type) - skb->nh.raw);
 259                 return -1;
 260         }
 261
 262         if (hdr->hdrlen & 0x01) {
 263                 IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 264                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, (&hdr->hdrlen) - skb->nh.raw);
 265                 return -1;
 266         }
 267
 268         /*
 269          *      This is the routing header forwarding algorithm from
 270          *      RFC 2460, page 16.
 271          */
 272
 273         n = hdr->hdrlen >> 1;
 274
 275         if (hdr->segments_left > n) {
 276                 IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 277                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, (&hdr->segments_left) - skb->nh.raw);
 278                 return -1;
 279         }
 280
 281         /* We are about to mangle packet header. Be careful!
 282            Do not damage packets queued somewhere.
 283          */
 284         if (skb_cloned(skb)) {
 285                 struct sk_buff *skb2 = skb_copy(skb, GFP_ATOMIC);
 286                 kfree_skb(skb);
 287                 /* the copy is a forwarded packet */
 288                 if (skb2 == NULL) {
 289                         IP6_INC_STATS_BH(IPSTATS_MIB_OUTDISCARDS);
 290                         return -1;
 291                 }
 292                 *skbp = skb = skb2;
 293                 opt = IP6CB(skb2);
 294                 hdr = (struct ipv6_rt_hdr *) skb2->h.raw;
 295         }
 296
 297         if (skb->ip_summed == CHECKSUM_HW)
 298                 skb->ip_summed = CHECKSUM_NONE;
 299
 300         i = n - --hdr->segments_left;
 301
 302         rthdr = (struct rt0_hdr *) hdr;
 303         addr = rthdr->addr;
 304         addr += i - 1;
 305
 306         if (ipv6_addr_is_multicast(addr)) {
 307                 IP6_INC_STATS_BH(IPSTATS_MIB_INADDRERRORS);
 308                 kfree_skb(skb);
 309                 return -1;
 310         }
 311
 312         ipv6_addr_copy(&daddr, addr);
 313         ipv6_addr_copy(addr, &skb->nh.ipv6h->daddr);
 314         ipv6_addr_copy(&skb->nh.ipv6h->daddr, &daddr);
 315
 316         dst_release(xchg(&skb->dst, NULL));
 317         ip6_route_input(skb);
 318         if (skb->dst->error) {
 319                 skb_push(skb, skb->data - skb->nh.raw);
 320                 dst_input(skb);
 321                 return -1;
 322         }
 323
 324         if (skb->dst->dev->flags&IFF_LOOPBACK) {
 325                 if (skb->nh.ipv6h->hop_limit <= 1) {
 326                         IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 327                         icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
 328                                     0, skb->dev);
 329                         kfree_skb(skb);
 330                         return -1;
 331                 }
 332                 skb->nh.ipv6h->hop_limit--;
 333                 goto looped_back;
 334         }
 335
 336         skb_push(skb, skb->data - skb->nh.raw);
 337         dst_input(skb);
 338         return -1;
 339 }
 340
 341 static struct inet6_protocol rthdr_protocol = {
 342         .handler        =       ipv6_rthdr_rcv,
 343         .flags          =       INET6_PROTO_NOPOLICY,
 344 };
 345
 346 void __init ipv6_rthdr_init(void)
 347 {
 348         if (inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING) < 0)
 349                 printk(KERN_ERR "ipv6_rthdr_init: Could not register protocol\n");
 350 };
 351
 352 /*
 353    This function inverts received rthdr.
 354    NOTE: specs allow to make it automatically only if
 355    packet authenticated.
 356
 357    I will not discuss it here (though, I am really pissed off at
 358    this stupid requirement making rthdr idea useless)
 359
 360    Actually, it creates severe problems  for us.
 361    Embryonic requests has no associated sockets,
 362    so that user have no control over it and
 363    cannot not only to set reply options, but
 364    even to know, that someone wants to connect
 365    without success. :-(
 366
 367    For now we need to test the engine, so that I created
 368    temporary (or permanent) backdoor.
 369    If listening socket set IPV6_RTHDR to 2, then we invert header.
 370                                                    --ANK (980729)
 371  */
 372
 373 struct ipv6_txoptions *
 374 ipv6_invert_rthdr(struct sock *sk, struct ipv6_rt_hdr *hdr)
 375 {
 376         /* Received rthdr:
 377
 378            [ H1 -> H2 -> ... H_prev ]  daddr=ME
 379
 380            Inverted result:
 381            [ H_prev -> ... -> H1 ] daddr =sender
 382
 383            Note, that IP output engine will rewrite this rthdr
 384            by rotating it left by one addr.
 385          */
 386
 387         int n, i;
 388         struct rt0_hdr *rthdr = (struct rt0_hdr*)hdr;
 389         struct rt0_hdr *irthdr;
 390         struct ipv6_txoptions *opt;
 391         int hdrlen = ipv6_optlen(hdr);
 392
 393         if (hdr->segments_left ||
 394             hdr->type != IPV6_SRCRT_TYPE_0 ||
 395             hdr->hdrlen & 0x01)
 396                 return NULL;
 397
 398         n = hdr->hdrlen >> 1;
 399         opt = sock_kmalloc(sk, sizeof(*opt) + hdrlen, GFP_ATOMIC);
 400         if (opt == NULL)
 401                 return NULL;
 402         memset(opt, 0, sizeof(*opt));
 403         opt->tot_len = sizeof(*opt) + hdrlen;
 404         opt->srcrt = (void*)(opt+1);
 405         opt->opt_nflen = hdrlen;
 406
 407         memcpy(opt->srcrt, hdr, sizeof(*hdr));
 408         irthdr = (struct rt0_hdr*)opt->srcrt;
 409         irthdr->reserved = 0;
 410         opt->srcrt->segments_left = n;
 411         for (i=0; i<n; i++)
 412                 memcpy(irthdr->addr+i, rthdr->addr+(n-1-i), 16);
 413         return opt;
 414 }
 415
 416 /**********************************
 417   Hop-by-hop options.
 418  **********************************/
 419
 420 /* Router Alert as of RFC 2711 */
 421
 422 static int ipv6_hop_ra(struct sk_buff *skb, int optoff)
 423 {
 424         if (skb->nh.raw[optoff+1] == 2) {
 425                 IP6CB(skb)->ra = optoff;
 426                 return 1;
 427         }
 428         LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_ra: wrong RA length %d\n",
 429                        skb->nh.raw[optoff+1]);
 430         kfree_skb(skb);
 431         return 0;
 432 }
 433
 434 /* Jumbo payload */
 435
 436 static int ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
 437 {
 438         u32 pkt_len;
 439
 440         if (skb->nh.raw[optoff+1] != 4 || (optoff&3) != 2) {
 441                 LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
 442                                skb->nh.raw[optoff+1]);
 443                 IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 444                 goto drop;
 445         }
 446
 447         pkt_len = ntohl(*(u32*)(skb->nh.raw+optoff+2));
 448         if (pkt_len <= IPV6_MAXPLEN) {
 449                 IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 450                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2);
 451                 return 0;
 452         }
 453         if (skb->nh.ipv6h->payload_len) {
 454                 IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 455                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff);
 456                 return 0;
 457         }
 458
 459         if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
 460                 IP6_INC_STATS_BH(IPSTATS_MIB_INTRUNCATEDPKTS);
 461                 goto drop;
 462         }
 463
 464         if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 465                 goto drop;
 466
 467         return 1;
 468
 469 drop:
 470         kfree_skb(skb);
 471         return 0;
 472 }
 473
 474 static struct tlvtype_proc tlvprochopopt_lst[] = {
 475         {
 476                 .type   = IPV6_TLV_ROUTERALERT,
 477                 .func   = ipv6_hop_ra,
 478         },
 479         {
 480                 .type   = IPV6_TLV_JUMBO,
 481                 .func   = ipv6_hop_jumbo,
 482         },
 483         { -1, }
 484 };
 485
 486 int ipv6_parse_hopopts(struct sk_buff *skb, int nhoff)
 487 {
 488         IP6CB(skb)->hop = sizeof(struct ipv6hdr);
 489         if (ip6_parse_tlv(tlvprochopopt_lst, skb))
 490                 return sizeof(struct ipv6hdr);
 491         return -1;
 492 }
 493
 494 /*
 495  *      Creating outbound headers.
 496  *
 497  *      "build" functions work when skb is filled from head to tail (datagram)
 498  *      "push"  functions work when headers are added from tail to head (tcp)
 499  *
 500  *      In both cases we assume, that caller reserved enough room
 501  *      for headers.
 502  */
 503
 504 static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
 505                             struct ipv6_rt_hdr *opt,
 506                             struct in6_addr **addr_p)
 507 {
 508         struct rt0_hdr *phdr, *ihdr;
 509         int hops;
 510
 511         ihdr = (struct rt0_hdr *) opt;
 512
 513         phdr = (struct rt0_hdr *) skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
 514         memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
 515
 516         hops = ihdr->rt_hdr.hdrlen >> 1;
 517
 518         if (hops > 1)
 519                 memcpy(phdr->addr, ihdr->addr + 1,
 520                        (hops - 1) * sizeof(struct in6_addr));
 521
 522         ipv6_addr_copy(phdr->addr + (hops - 1), *addr_p);
 523         *addr_p = ihdr->addr;
 524
 525         phdr->rt_hdr.nexthdr = *proto;
 526         *proto = NEXTHDR_ROUTING;
 527 }
 528
 529 static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
 530 {
 531         struct ipv6_opt_hdr *h = (struct ipv6_opt_hdr *)skb_push(skb, ipv6_optlen(opt));
 532
 533         memcpy(h, opt, ipv6_optlen(opt));
 534         h->nexthdr = *proto;
 535         *proto = type;
 536 }
 537
 538 void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
 539                           u8 *proto,
 540                           struct in6_addr **daddr)
 541 {
 542         if (opt->srcrt) {
 543                 ipv6_push_rthdr(skb, proto, opt->srcrt, daddr);
 544                 /*
 545                  * IPV6_RTHDRDSTOPTS is ignored
 546                  * unless IPV6_RTHDR is set (RFC3542).
 547                  */
 548                 if (opt->dst0opt)
 549                         ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
 550         }
 551         if (opt->hopopt)
 552                 ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
 553 }
 554
 555 void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
 556 {
 557         if (opt->dst1opt)
 558                 ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
 559 }
 560
 561 struct ipv6_txoptions *
 562 ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
 563 {
 564         struct ipv6_txoptions *opt2;
 565
 566         opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
 567         if (opt2) {
 568                 long dif = (char*)opt2 - (char*)opt;
 569                 memcpy(opt2, opt, opt->tot_len);
 570                 if (opt2->hopopt)
 571                         *((char**)&opt2->hopopt) += dif;
 572                 if (opt2->dst0opt)
 573                         *((char**)&opt2->dst0opt) += dif;
 574                 if (opt2->dst1opt)
 575                         *((char**)&opt2->dst1opt) += dif;
 576                 if (opt2->srcrt)
 577                         *((char**)&opt2->srcrt) += dif;
 578         }
 579         return opt2;
 580 }
 581
 582 static int ipv6_renew_option(void *ohdr,
 583                              struct ipv6_opt_hdr __user *newopt, int newoptlen,
 584                              int inherit,
 585                              struct ipv6_opt_hdr **hdr,
 586                              char **p)
 587 {
 588         if (inherit) {
 589                 if (ohdr) {
 590                         memcpy(*p, ohdr, ipv6_optlen((struct ipv6_opt_hdr *)ohdr));
 591                         *hdr = (struct ipv6_opt_hdr *)*p;
 592                         *p += CMSG_ALIGN(ipv6_optlen(*(struct ipv6_opt_hdr **)hdr));
 593                 }
 594         } else {
 595                 if (newopt) {
 596                         if (copy_from_user(*p, newopt, newoptlen))
 597                                 return -EFAULT;
 598                         *hdr = (struct ipv6_opt_hdr *)*p;
 599                         if (ipv6_optlen(*(struct ipv6_opt_hdr **)hdr) > newoptlen)
 600                                 return -EINVAL;
 601                         *p += CMSG_ALIGN(newoptlen);
 602                 }
 603         }
 604         return 0;
 605 }
 606
 607 struct ipv6_txoptions *
 608 ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
 609                    int newtype,
 610                    struct ipv6_opt_hdr __user *newopt, int newoptlen)
 611 {
 612         int tot_len = 0;
 613         char *p;
 614         struct ipv6_txoptions *opt2;
 615         int err;
 616
 617         if (newtype != IPV6_HOPOPTS && opt->hopopt)
 618                 tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
 619         if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
 620                 tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
 621         if (newtype != IPV6_RTHDR && opt->srcrt)
 622                 tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
 623         if (newtype != IPV6_DSTOPTS && opt->dst1opt)
 624                 tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
 625         if (newopt && newoptlen)
 626                 tot_len += CMSG_ALIGN(newoptlen);
 627
 628         if (!tot_len)
 629                 return NULL;
 630
 631         opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
 632         if (!opt2)
 633                 return ERR_PTR(-ENOBUFS);
 634
 635         memset(opt2, 0, tot_len);
 636
 637         opt2->tot_len = tot_len;
 638         p = (char *)(opt2 + 1);
 639
 640         err = ipv6_renew_option(opt->hopopt, newopt, newoptlen,
 641                                 newtype != IPV6_HOPOPTS,
 642                                 &opt2->hopopt, &p);
 643         if (err)
 644                 goto out;
 645
 646         err = ipv6_renew_option(opt->dst0opt, newopt, newoptlen,
 647                                 newtype != IPV6_RTHDRDSTOPTS,
 648                                 &opt2->dst0opt, &p);
 649         if (err)
 650                 goto out;
 651
 652         err = ipv6_renew_option(opt->srcrt, newopt, newoptlen,
 653                                 newtype != IPV6_RTHDR,
 654                                 (struct ipv6_opt_hdr **)opt2->srcrt, &p);
 655         if (err)
 656                 goto out;
 657
 658         err = ipv6_renew_option(opt->dst1opt, newopt, newoptlen,
 659                                 newtype != IPV6_DSTOPTS,
 660                                 &opt2->dst1opt, &p);
 661         if (err)
 662                 goto out;
 663
 664         opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
 665                           (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
 666                           (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
 667         opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
 668
 669         return opt2;
 670 out:
 671         sock_kfree_s(sk, p, tot_len);
 672         return ERR_PTR(err);
 673 }
 674