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 EXPORT_SYMBOL_GPL(ipv6_invert_rthdr);
 417
 418 /**********************************
 419   Hop-by-hop options.
 420  **********************************/
 421
 422 /* Router Alert as of RFC 2711 */
 423
 424 static int ipv6_hop_ra(struct sk_buff *skb, int optoff)
 425 {
 426         if (skb->nh.raw[optoff+1] == 2) {
 427                 IP6CB(skb)->ra = optoff;
 428                 return 1;
 429         }
 430         LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_ra: wrong RA length %d\n",
 431                        skb->nh.raw[optoff+1]);
 432         kfree_skb(skb);
 433         return 0;
 434 }
 435
 436 /* Jumbo payload */
 437
 438 static int ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
 439 {
 440         u32 pkt_len;
 441
 442         if (skb->nh.raw[optoff+1] != 4 || (optoff&3) != 2) {
 443                 LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
 444                                skb->nh.raw[optoff+1]);
 445                 IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 446                 goto drop;
 447         }
 448
 449         pkt_len = ntohl(*(u32*)(skb->nh.raw+optoff+2));
 450         if (pkt_len <= IPV6_MAXPLEN) {
 451                 IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 452                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2);
 453                 return 0;
 454         }
 455         if (skb->nh.ipv6h->payload_len) {
 456                 IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 457                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff);
 458                 return 0;
 459         }
 460
 461         if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
 462                 IP6_INC_STATS_BH(IPSTATS_MIB_INTRUNCATEDPKTS);
 463                 goto drop;
 464         }
 465
 466         if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 467                 goto drop;
 468
 469         return 1;
 470
 471 drop:
 472         kfree_skb(skb);
 473         return 0;
 474 }
 475
 476 static struct tlvtype_proc tlvprochopopt_lst[] = {
 477         {
 478                 .type   = IPV6_TLV_ROUTERALERT,
 479                 .func   = ipv6_hop_ra,
 480         },
 481         {
 482                 .type   = IPV6_TLV_JUMBO,
 483                 .func   = ipv6_hop_jumbo,
 484         },
 485         { -1, }
 486 };
 487
 488 int ipv6_parse_hopopts(struct sk_buff *skb, int nhoff)
 489 {
 490         IP6CB(skb)->hop = sizeof(struct ipv6hdr);
 491         if (ip6_parse_tlv(tlvprochopopt_lst, skb))
 492                 return sizeof(struct ipv6hdr);
 493         return -1;
 494 }
 495
 496 /*
 497  *      Creating outbound headers.
 498  *
 499  *      "build" functions work when skb is filled from head to tail (datagram)
 500  *      "push"  functions work when headers are added from tail to head (tcp)
 501  *
 502  *      In both cases we assume, that caller reserved enough room
 503  *      for headers.
 504  */
 505
 506 static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
 507                             struct ipv6_rt_hdr *opt,
 508                             struct in6_addr **addr_p)
 509 {
 510         struct rt0_hdr *phdr, *ihdr;
 511         int hops;
 512
 513         ihdr = (struct rt0_hdr *) opt;
 514
 515         phdr = (struct rt0_hdr *) skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
 516         memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
 517
 518         hops = ihdr->rt_hdr.hdrlen >> 1;
 519
 520         if (hops > 1)
 521                 memcpy(phdr->addr, ihdr->addr + 1,
 522                        (hops - 1) * sizeof(struct in6_addr));
 523
 524         ipv6_addr_copy(phdr->addr + (hops - 1), *addr_p);
 525         *addr_p = ihdr->addr;
 526
 527         phdr->rt_hdr.nexthdr = *proto;
 528         *proto = NEXTHDR_ROUTING;
 529 }
 530
 531 static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
 532 {
 533         struct ipv6_opt_hdr *h = (struct ipv6_opt_hdr *)skb_push(skb, ipv6_optlen(opt));
 534
 535         memcpy(h, opt, ipv6_optlen(opt));
 536         h->nexthdr = *proto;
 537         *proto = type;
 538 }
 539
 540 void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
 541                           u8 *proto,
 542                           struct in6_addr **daddr)
 543 {
 544         if (opt->srcrt) {
 545                 ipv6_push_rthdr(skb, proto, opt->srcrt, daddr);
 546                 /*
 547                  * IPV6_RTHDRDSTOPTS is ignored
 548                  * unless IPV6_RTHDR is set (RFC3542).
 549                  */
 550                 if (opt->dst0opt)
 551                         ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
 552         }
 553         if (opt->hopopt)
 554                 ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
 555 }
 556
 557 void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
 558 {
 559         if (opt->dst1opt)
 560                 ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
 561 }
 562
 563 struct ipv6_txoptions *
 564 ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
 565 {
 566         struct ipv6_txoptions *opt2;
 567
 568         opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
 569         if (opt2) {
 570                 long dif = (char*)opt2 - (char*)opt;
 571                 memcpy(opt2, opt, opt->tot_len);
 572                 if (opt2->hopopt)
 573                         *((char**)&opt2->hopopt) += dif;
 574                 if (opt2->dst0opt)
 575                         *((char**)&opt2->dst0opt) += dif;
 576                 if (opt2->dst1opt)
 577                         *((char**)&opt2->dst1opt) += dif;
 578                 if (opt2->srcrt)
 579                         *((char**)&opt2->srcrt) += dif;
 580         }
 581         return opt2;
 582 }
 583
 584 EXPORT_SYMBOL_GPL(ipv6_dup_options);
 585
 586 static int ipv6_renew_option(void *ohdr,
 587                              struct ipv6_opt_hdr __user *newopt, int newoptlen,
 588                              int inherit,
 589                              struct ipv6_opt_hdr **hdr,
 590                              char **p)
 591 {
 592         if (inherit) {
 593                 if (ohdr) {
 594                         memcpy(*p, ohdr, ipv6_optlen((struct ipv6_opt_hdr *)ohdr));
 595                         *hdr = (struct ipv6_opt_hdr *)*p;
 596                         *p += CMSG_ALIGN(ipv6_optlen(*(struct ipv6_opt_hdr **)hdr));
 597                 }
 598         } else {
 599                 if (newopt) {
 600                         if (copy_from_user(*p, newopt, newoptlen))
 601                                 return -EFAULT;
 602                         *hdr = (struct ipv6_opt_hdr *)*p;
 603                         if (ipv6_optlen(*(struct ipv6_opt_hdr **)hdr) > newoptlen)
 604                                 return -EINVAL;
 605                         *p += CMSG_ALIGN(newoptlen);
 606                 }
 607         }
 608         return 0;
 609 }
 610
 611 struct ipv6_txoptions *
 612 ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
 613                    int newtype,
 614                    struct ipv6_opt_hdr __user *newopt, int newoptlen)
 615 {
 616         int tot_len = 0;
 617         char *p;
 618         struct ipv6_txoptions *opt2;
 619         int err;
 620
 621         if (newtype != IPV6_HOPOPTS && opt->hopopt)
 622                 tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
 623         if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
 624                 tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
 625         if (newtype != IPV6_RTHDR && opt->srcrt)
 626                 tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
 627         if (newtype != IPV6_DSTOPTS && opt->dst1opt)
 628                 tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
 629         if (newopt && newoptlen)
 630                 tot_len += CMSG_ALIGN(newoptlen);
 631
 632         if (!tot_len)
 633                 return NULL;
 634
 635         tot_len += sizeof(*opt2);
 636         opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
 637         if (!opt2)
 638                 return ERR_PTR(-ENOBUFS);
 639
 640         memset(opt2, 0, tot_len);
 641
 642         opt2->tot_len = tot_len;
 643         p = (char *)(opt2 + 1);
 644
 645         err = ipv6_renew_option(opt->hopopt, newopt, newoptlen,
 646                                 newtype != IPV6_HOPOPTS,
 647                                 &opt2->hopopt, &p);
 648         if (err)
 649                 goto out;
 650
 651         err = ipv6_renew_option(opt->dst0opt, newopt, newoptlen,
 652                                 newtype != IPV6_RTHDRDSTOPTS,
 653                                 &opt2->dst0opt, &p);
 654         if (err)
 655                 goto out;
 656
 657         err = ipv6_renew_option(opt->srcrt, newopt, newoptlen,
 658                                 newtype != IPV6_RTHDR,
 659                                 (struct ipv6_opt_hdr **)opt2->srcrt, &p);
 660         if (err)
 661                 goto out;
 662
 663         err = ipv6_renew_option(opt->dst1opt, newopt, newoptlen,
 664                                 newtype != IPV6_DSTOPTS,
 665                                 &opt2->dst1opt, &p);
 666         if (err)
 667                 goto out;
 668
 669         opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
 670                           (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
 671                           (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
 672         opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
 673
 674         return opt2;
 675 out:
 676         sock_kfree_s(sk, opt2, opt2->tot_len);
 677         return ERR_PTR(err);
 678 }
 679
 680 struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space,
 681                                           struct ipv6_txoptions *opt)
 682 {
 683         /*
 684          * ignore the dest before srcrt unless srcrt is being included.
 685          * --yoshfuji
 686          */
 687         if (opt && opt->dst0opt && !opt->srcrt) {
 688                 if (opt_space != opt) {
 689                         memcpy(opt_space, opt, sizeof(*opt_space));
 690                         opt = opt_space;
 691                 }
 692                 opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
 693                 opt->dst0opt = NULL;
 694         }
 695
 696         return opt;
 697 }
 698