net/ipv4/ip_options.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   4  *              operating system.  INET is implemented using the  BSD Socket
   5  *              interface as the means of communication with the user level.
   6  *
   7  *              The options processing module for ip.c
   8  *
   9  * Authors:     A.N.Kuznetsov
  10  *
  11  */
  12
  13 #define pr_fmt(fmt) "IPv4: " fmt
  14
  15 #include <linux/capability.h>
  16 #include <linux/module.h>
  17 #include <linux/slab.h>
  18 #include <linux/types.h>
  19 #include <linux/uaccess.h>
  20 #include <asm/unaligned.h>
  21 #include <linux/skbuff.h>
  22 #include <linux/ip.h>
  23 #include <linux/icmp.h>
  24 #include <linux/netdevice.h>
  25 #include <linux/rtnetlink.h>
  26 #include <net/sock.h>
  27 #include <net/ip.h>
  28 #include <net/icmp.h>
  29 #include <net/route.h>
  30 #include <net/cipso_ipv4.h>
  31 #include <net/ip_fib.h>
  32
  33 /*
  34  * Write options to IP header, record destination address to
  35  * source route option, address of outgoing interface
  36  * (we should already know it, so that this  function is allowed be
  37  * called only after routing decision) and timestamp,
  38  * if we originate this datagram.
  39  *
  40  * daddr is real destination address, next hop is recorded in IP header.
  41  * saddr is address of outgoing interface.
  42  */
  43
  44 void ip_options_build(struct sk_buff *skb, struct ip_options *opt,
  45                       __be32 daddr, struct rtable *rt, int is_frag)
  46 {
  47         unsigned char *iph = skb_network_header(skb);
  48
  49         memcpy(&(IPCB(skb)->opt), opt, sizeof(struct ip_options));
  50         memcpy(iph+sizeof(struct iphdr), opt->__data, opt->optlen);
  51         opt = &(IPCB(skb)->opt);
  52
  53         if (opt->srr)
  54                 memcpy(iph+opt->srr+iph[opt->srr+1]-4, &daddr, 4);
  55
  56         if (!is_frag) {
  57                 if (opt->rr_needaddr)
  58                         ip_rt_get_source(iph+opt->rr+iph[opt->rr+2]-5, skb, rt);
  59                 if (opt->ts_needaddr)
  60                         ip_rt_get_source(iph+opt->ts+iph[opt->ts+2]-9, skb, rt);
  61                 if (opt->ts_needtime) {
  62                         __be32 midtime;
  63
  64                         midtime = inet_current_timestamp();
  65                         memcpy(iph+opt->ts+iph[opt->ts+2]-5, &midtime, 4);
  66                 }
  67                 return;
  68         }
  69         if (opt->rr) {
  70                 memset(iph+opt->rr, IPOPT_NOP, iph[opt->rr+1]);
  71                 opt->rr = 0;
  72                 opt->rr_needaddr = 0;
  73         }
  74         if (opt->ts) {
  75                 memset(iph+opt->ts, IPOPT_NOP, iph[opt->ts+1]);
  76                 opt->ts = 0;
  77                 opt->ts_needaddr = opt->ts_needtime = 0;
  78         }
  79 }
  80
  81 /*
  82  * Provided (sopt, skb) points to received options,
  83  * build in dopt compiled option set appropriate for answering.
  84  * i.e. invert SRR option, copy anothers,
  85  * and grab room in RR/TS options.
  86  *
  87  * NOTE: dopt cannot point to skb.
  88  */
  89
  90 int __ip_options_echo(struct net *net, struct ip_options *dopt,
  91                       struct sk_buff *skb, const struct ip_options *sopt)
  92 {
  93         unsigned char *sptr, *dptr;
  94         int soffset, doffset;
  95         int     optlen;
  96
  97         memset(dopt, 0, sizeof(struct ip_options));
  98
  99         if (sopt->optlen == 0)
 100                 return 0;
 101
 102         sptr = skb_network_header(skb);
 103         dptr = dopt->__data;
 104
 105         if (sopt->rr) {
 106                 optlen  = sptr[sopt->rr+1];
 107                 soffset = sptr[sopt->rr+2];
 108                 dopt->rr = dopt->optlen + sizeof(struct iphdr);
 109                 memcpy(dptr, sptr+sopt->rr, optlen);
 110                 if (sopt->rr_needaddr && soffset <= optlen) {
 111                         if (soffset + 3 > optlen)
 112                                 return -EINVAL;
 113                         dptr[2] = soffset + 4;
 114                         dopt->rr_needaddr = 1;
 115                 }
 116                 dptr += optlen;
 117                 dopt->optlen += optlen;
 118         }
 119         if (sopt->ts) {
 120                 optlen = sptr[sopt->ts+1];
 121                 soffset = sptr[sopt->ts+2];
 122                 dopt->ts = dopt->optlen + sizeof(struct iphdr);
 123                 memcpy(dptr, sptr+sopt->ts, optlen);
 124                 if (soffset <= optlen) {
 125                         if (sopt->ts_needaddr) {
 126                                 if (soffset + 3 > optlen)
 127                                         return -EINVAL;
 128                                 dopt->ts_needaddr = 1;
 129                                 soffset += 4;
 130                         }
 131                         if (sopt->ts_needtime) {
 132                                 if (soffset + 3 > optlen)
 133                                         return -EINVAL;
 134                                 if ((dptr[3]&0xF) != IPOPT_TS_PRESPEC) {
 135                                         dopt->ts_needtime = 1;
 136                                         soffset += 4;
 137                                 } else {
 138                                         dopt->ts_needtime = 0;
 139
 140                                         if (soffset + 7 <= optlen) {
 141                                                 __be32 addr;
 142
 143                                                 memcpy(&addr, dptr+soffset-1, 4);
 144                                                 if (inet_addr_type(net, addr) != RTN_UNICAST) {
 145                                                         dopt->ts_needtime = 1;
 146                                                         soffset += 8;
 147                                                 }
 148                                         }
 149                                 }
 150                         }
 151                         dptr[2] = soffset;
 152                 }
 153                 dptr += optlen;
 154                 dopt->optlen += optlen;
 155         }
 156         if (sopt->srr) {
 157                 unsigned char *start = sptr+sopt->srr;
 158                 __be32 faddr;
 159
 160                 optlen  = start[1];
 161                 soffset = start[2];
 162                 doffset = 0;
 163                 if (soffset > optlen)
 164                         soffset = optlen + 1;
 165                 soffset -= 4;
 166                 if (soffset > 3) {
 167                         memcpy(&faddr, &start[soffset-1], 4);
 168                         for (soffset -= 4, doffset = 4; soffset > 3; soffset -= 4, doffset += 4)
 169                                 memcpy(&dptr[doffset-1], &start[soffset-1], 4);
 170                         /*
 171                          * RFC1812 requires to fix illegal source routes.
 172                          */
 173                         if (memcmp(&ip_hdr(skb)->saddr,
 174                                    &start[soffset + 3], 4) == 0)
 175                                 doffset -= 4;
 176                 }
 177                 if (doffset > 3) {
 178                         dopt->faddr = faddr;
 179                         dptr[0] = start[0];
 180                         dptr[1] = doffset+3;
 181                         dptr[2] = 4;
 182                         dptr += doffset+3;
 183                         dopt->srr = dopt->optlen + sizeof(struct iphdr);
 184                         dopt->optlen += doffset+3;
 185                         dopt->is_strictroute = sopt->is_strictroute;
 186                 }
 187         }
 188         if (sopt->cipso) {
 189                 optlen  = sptr[sopt->cipso+1];
 190                 dopt->cipso = dopt->optlen+sizeof(struct iphdr);
 191                 memcpy(dptr, sptr+sopt->cipso, optlen);
 192                 dptr += optlen;
 193                 dopt->optlen += optlen;
 194         }
 195         while (dopt->optlen & 3) {
 196                 *dptr++ = IPOPT_END;
 197                 dopt->optlen++;
 198         }
 199         return 0;
 200 }
 201
 202 /*
 203  *      Options "fragmenting", just fill options not
 204  *      allowed in fragments with NOOPs.
 205  *      Simple and stupid 8), but the most efficient way.
 206  */
 207
 208 void ip_options_fragment(struct sk_buff *skb)
 209 {
 210         unsigned char *optptr = skb_network_header(skb) + sizeof(struct iphdr);
 211         struct ip_options *opt = &(IPCB(skb)->opt);
 212         int  l = opt->optlen;
 213         int  optlen;
 214
 215         while (l > 0) {
 216                 switch (*optptr) {
 217                 case IPOPT_END:
 218                         return;
 219                 case IPOPT_NOOP:
 220                         l--;
 221                         optptr++;
 222                         continue;
 223                 }
 224                 optlen = optptr[1];
 225                 if (optlen < 2 || optlen > l)
 226                   return;
 227                 if (!IPOPT_COPIED(*optptr))
 228                         memset(optptr, IPOPT_NOOP, optlen);
 229                 l -= optlen;
 230                 optptr += optlen;
 231         }
 232         opt->ts = 0;
 233         opt->rr = 0;
 234         opt->rr_needaddr = 0;
 235         opt->ts_needaddr = 0;
 236         opt->ts_needtime = 0;
 237 }
 238
 239 /* helper used by ip_options_compile() to call fib_compute_spec_dst()
 240  * at most one time.
 241  */
 242 static void spec_dst_fill(__be32 *spec_dst, struct sk_buff *skb)
 243 {
 244         if (*spec_dst == htonl(INADDR_ANY))
 245                 *spec_dst = fib_compute_spec_dst(skb);
 246 }
 247
 248 /*
 249  * Verify options and fill pointers in struct options.
 250  * Caller should clear *opt, and set opt->data.
 251  * If opt == NULL, then skb->data should point to IP header.
 252  */
 253
 254 int ip_options_compile(struct net *net,
 255                        struct ip_options *opt, struct sk_buff *skb)
 256 {
 257         __be32 spec_dst = htonl(INADDR_ANY);
 258         unsigned char *pp_ptr = NULL;
 259         struct rtable *rt = NULL;
 260         unsigned char *optptr;
 261         unsigned char *iph;
 262         int optlen, l;
 263
 264         if (skb) {
 265                 rt = skb_rtable(skb);
 266                 optptr = (unsigned char *)&(ip_hdr(skb)[1]);
 267         } else
 268                 optptr = opt->__data;
 269         iph = optptr - sizeof(struct iphdr);
 270
 271         for (l = opt->optlen; l > 0; ) {
 272                 switch (*optptr) {
 273                 case IPOPT_END:
 274                         for (optptr++, l--; l > 0; optptr++, l--) {
 275                                 if (*optptr != IPOPT_END) {
 276                                         *optptr = IPOPT_END;
 277                                         opt->is_changed = 1;
 278                                 }
 279                         }
 280                         goto eol;
 281                 case IPOPT_NOOP:
 282                         l--;
 283                         optptr++;
 284                         continue;
 285                 }
 286                 if (unlikely(l < 2)) {
 287                         pp_ptr = optptr;
 288                         goto error;
 289                 }
 290                 optlen = optptr[1];
 291                 if (optlen < 2 || optlen > l) {
 292                         pp_ptr = optptr;
 293                         goto error;
 294                 }
 295                 switch (*optptr) {
 296                 case IPOPT_SSRR:
 297                 case IPOPT_LSRR:
 298                         if (optlen < 3) {
 299                                 pp_ptr = optptr + 1;
 300                                 goto error;
 301                         }
 302                         if (optptr[2] < 4) {
 303                                 pp_ptr = optptr + 2;
 304                                 goto error;
 305                         }
 306                         /* NB: cf RFC-1812 5.2.4.1 */
 307                         if (opt->srr) {
 308                                 pp_ptr = optptr;
 309                                 goto error;
 310                         }
 311                         if (!skb) {
 312                                 if (optptr[2] != 4 || optlen < 7 || ((optlen-3) & 3)) {
 313                                         pp_ptr = optptr + 1;
 314                                         goto error;
 315                                 }
 316                                 memcpy(&opt->faddr, &optptr[3], 4);
 317                                 if (optlen > 7)
 318                                         memmove(&optptr[3], &optptr[7], optlen-7);
 319                         }
 320                         opt->is_strictroute = (optptr[0] == IPOPT_SSRR);
 321                         opt->srr = optptr - iph;
 322                         break;
 323                 case IPOPT_RR:
 324                         if (opt->rr) {
 325                                 pp_ptr = optptr;
 326                                 goto error;
 327                         }
 328                         if (optlen < 3) {
 329                                 pp_ptr = optptr + 1;
 330                                 goto error;
 331                         }
 332                         if (optptr[2] < 4) {
 333                                 pp_ptr = optptr + 2;
 334                                 goto error;
 335                         }
 336                         if (optptr[2] <= optlen) {
 337                                 if (optptr[2]+3 > optlen) {
 338                                         pp_ptr = optptr + 2;
 339                                         goto error;
 340                                 }
 341                                 if (rt) {
 342                                         spec_dst_fill(&spec_dst, skb);
 343                                         memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
 344                                         opt->is_changed = 1;
 345                                 }
 346                                 optptr[2] += 4;
 347                                 opt->rr_needaddr = 1;
 348                         }
 349                         opt->rr = optptr - iph;
 350                         break;
 351                 case IPOPT_TIMESTAMP:
 352                         if (opt->ts) {
 353                                 pp_ptr = optptr;
 354                                 goto error;
 355                         }
 356                         if (optlen < 4) {
 357                                 pp_ptr = optptr + 1;
 358                                 goto error;
 359                         }
 360                         if (optptr[2] < 5) {
 361                                 pp_ptr = optptr + 2;
 362                                 goto error;
 363                         }
 364                         if (optptr[2] <= optlen) {
 365                                 unsigned char *timeptr = NULL;
 366                                 if (optptr[2]+3 > optlen) {
 367                                         pp_ptr = optptr + 2;
 368                                         goto error;
 369                                 }
 370                                 switch (optptr[3]&0xF) {
 371                                 case IPOPT_TS_TSONLY:
 372                                         if (skb)
 373                                                 timeptr = &optptr[optptr[2]-1];
 374                                         opt->ts_needtime = 1;
 375                                         optptr[2] += 4;
 376                                         break;
 377                                 case IPOPT_TS_TSANDADDR:
 378                                         if (optptr[2]+7 > optlen) {
 379                                                 pp_ptr = optptr + 2;
 380                                                 goto error;
 381                                         }
 382                                         if (rt)  {
 383                                                 spec_dst_fill(&spec_dst, skb);
 384                                                 memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
 385                                                 timeptr = &optptr[optptr[2]+3];
 386                                         }
 387                                         opt->ts_needaddr = 1;
 388                                         opt->ts_needtime = 1;
 389                                         optptr[2] += 8;
 390                                         break;
 391                                 case IPOPT_TS_PRESPEC:
 392                                         if (optptr[2]+7 > optlen) {
 393                                                 pp_ptr = optptr + 2;
 394                                                 goto error;
 395                                         }
 396                                         {
 397                                                 __be32 addr;
 398                                                 memcpy(&addr, &optptr[optptr[2]-1], 4);
 399                                                 if (inet_addr_type(net, addr) == RTN_UNICAST)
 400                                                         break;
 401                                                 if (skb)
 402                                                         timeptr = &optptr[optptr[2]+3];
 403                                         }
 404                                         opt->ts_needtime = 1;
 405                                         optptr[2] += 8;
 406                                         break;
 407                                 default:
 408                                         if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) {
 409                                                 pp_ptr = optptr + 3;
 410                                                 goto error;
 411                                         }
 412                                         break;
 413                                 }
 414                                 if (timeptr) {
 415                                         __be32 midtime;
 416
 417                                         midtime = inet_current_timestamp();
 418                                         memcpy(timeptr, &midtime, 4);
 419                                         opt->is_changed = 1;
 420                                 }
 421                         } else if ((optptr[3]&0xF) != IPOPT_TS_PRESPEC) {
 422                                 unsigned int overflow = optptr[3]>>4;
 423                                 if (overflow == 15) {
 424                                         pp_ptr = optptr + 3;
 425                                         goto error;
 426                                 }
 427                                 if (skb) {
 428                                         optptr[3] = (optptr[3]&0xF)|((overflow+1)<<4);
 429                                         opt->is_changed = 1;
 430                                 }
 431                         }
 432                         opt->ts = optptr - iph;
 433                         break;
 434                 case IPOPT_RA:
 435                         if (optlen < 4) {
 436                                 pp_ptr = optptr + 1;
 437                                 goto error;
 438                         }
 439                         if (optptr[2] == 0 && optptr[3] == 0)
 440                                 opt->router_alert = optptr - iph;
 441                         break;
 442                 case IPOPT_CIPSO:
 443                         if ((!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) || opt->cipso) {
 444                                 pp_ptr = optptr;
 445                                 goto error;
 446                         }
 447                         opt->cipso = optptr - iph;
 448                         if (cipso_v4_validate(skb, &optptr)) {
 449                                 pp_ptr = optptr;
 450                                 goto error;
 451                         }
 452                         break;
 453                 case IPOPT_SEC:
 454                 case IPOPT_SID:
 455                 default:
 456                         if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) {
 457                                 pp_ptr = optptr;
 458                                 goto error;
 459                         }
 460                         break;
 461                 }
 462                 l -= optlen;
 463                 optptr += optlen;
 464         }
 465
 466 eol:
 467         if (!pp_ptr)
 468                 return 0;
 469
 470 error:
 471         if (skb) {
 472                 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((pp_ptr-iph)<<24));
 473         }
 474         return -EINVAL;
 475 }
 476 EXPORT_SYMBOL(ip_options_compile);
 477
 478 /*
 479  *      Undo all the changes done by ip_options_compile().
 480  */
 481
 482 void ip_options_undo(struct ip_options *opt)
 483 {
 484         if (opt->srr) {
 485                 unsigned  char *optptr = opt->__data+opt->srr-sizeof(struct  iphdr);
 486                 memmove(optptr+7, optptr+3, optptr[1]-7);
 487                 memcpy(optptr+3, &opt->faddr, 4);
 488         }
 489         if (opt->rr_needaddr) {
 490                 unsigned  char *optptr = opt->__data+opt->rr-sizeof(struct  iphdr);
 491                 optptr[2] -= 4;
 492                 memset(&optptr[optptr[2]-1], 0, 4);
 493         }
 494         if (opt->ts) {
 495                 unsigned  char *optptr = opt->__data+opt->ts-sizeof(struct  iphdr);
 496                 if (opt->ts_needtime) {
 497                         optptr[2] -= 4;
 498                         memset(&optptr[optptr[2]-1], 0, 4);
 499                         if ((optptr[3]&0xF) == IPOPT_TS_PRESPEC)
 500                                 optptr[2] -= 4;
 501                 }
 502                 if (opt->ts_needaddr) {
 503                         optptr[2] -= 4;
 504                         memset(&optptr[optptr[2]-1], 0, 4);
 505                 }
 506         }
 507 }
 508
 509 static struct ip_options_rcu *ip_options_get_alloc(const int optlen)
 510 {
 511         return kzalloc(sizeof(struct ip_options_rcu) + ((optlen + 3) & ~3),
 512                        GFP_KERNEL);
 513 }
 514
 515 static int ip_options_get_finish(struct net *net, struct ip_options_rcu **optp,
 516                                  struct ip_options_rcu *opt, int optlen)
 517 {
 518         while (optlen & 3)
 519                 opt->opt.__data[optlen++] = IPOPT_END;
 520         opt->opt.optlen = optlen;
 521         if (optlen && ip_options_compile(net, &opt->opt, NULL)) {
 522                 kfree(opt);
 523                 return -EINVAL;
 524         }
 525         kfree(*optp);
 526         *optp = opt;
 527         return 0;
 528 }
 529
 530 int ip_options_get_from_user(struct net *net, struct ip_options_rcu **optp,
 531                              unsigned char __user *data, int optlen)
 532 {
 533         struct ip_options_rcu *opt = ip_options_get_alloc(optlen);
 534
 535         if (!opt)
 536                 return -ENOMEM;
 537         if (optlen && copy_from_user(opt->opt.__data, data, optlen)) {
 538                 kfree(opt);
 539                 return -EFAULT;
 540         }
 541         return ip_options_get_finish(net, optp, opt, optlen);
 542 }
 543
 544 int ip_options_get(struct net *net, struct ip_options_rcu **optp,
 545                    unsigned char *data, int optlen)
 546 {
 547         struct ip_options_rcu *opt = ip_options_get_alloc(optlen);
 548
 549         if (!opt)
 550                 return -ENOMEM;
 551         if (optlen)
 552                 memcpy(opt->opt.__data, data, optlen);
 553         return ip_options_get_finish(net, optp, opt, optlen);
 554 }
 555
 556 void ip_forward_options(struct sk_buff *skb)
 557 {
 558         struct   ip_options *opt        = &(IPCB(skb)->opt);
 559         unsigned char *optptr;
 560         struct rtable *rt = skb_rtable(skb);
 561         unsigned char *raw = skb_network_header(skb);
 562
 563         if (opt->rr_needaddr) {
 564                 optptr = (unsigned char *)raw + opt->rr;
 565                 ip_rt_get_source(&optptr[optptr[2]-5], skb, rt);
 566                 opt->is_changed = 1;
 567         }
 568         if (opt->srr_is_hit) {
 569                 int srrptr, srrspace;
 570
 571                 optptr = raw + opt->srr;
 572
 573                 for ( srrptr = optptr[2], srrspace = optptr[1];
 574                      srrptr <= srrspace;
 575                      srrptr += 4
 576                      ) {
 577                         if (srrptr + 3 > srrspace)
 578                                 break;
 579                         if (memcmp(&opt->nexthop, &optptr[srrptr-1], 4) == 0)
 580                                 break;
 581                 }
 582                 if (srrptr + 3 <= srrspace) {
 583                         opt->is_changed = 1;
 584                         ip_hdr(skb)->daddr = opt->nexthop;
 585                         ip_rt_get_source(&optptr[srrptr-1], skb, rt);
 586                         optptr[2] = srrptr+4;
 587                 } else {
 588                         net_crit_ratelimited("%s(): Argh! Destination lost!\n",
 589                                              __func__);
 590                 }
 591                 if (opt->ts_needaddr) {
 592                         optptr = raw + opt->ts;
 593                         ip_rt_get_source(&optptr[optptr[2]-9], skb, rt);
 594                         opt->is_changed = 1;
 595                 }
 596         }
 597         if (opt->is_changed) {
 598                 opt->is_changed = 0;
 599                 ip_send_check(ip_hdr(skb));
 600         }
 601 }
 602
 603 int ip_options_rcv_srr(struct sk_buff *skb)
 604 {
 605         struct ip_options *opt = &(IPCB(skb)->opt);
 606         int srrspace, srrptr;
 607         __be32 nexthop;
 608         struct iphdr *iph = ip_hdr(skb);
 609         unsigned char *optptr = skb_network_header(skb) + opt->srr;
 610         struct rtable *rt = skb_rtable(skb);
 611         struct rtable *rt2;
 612         unsigned long orefdst;
 613         int err;
 614
 615         if (!rt)
 616                 return 0;
 617
 618         if (skb->pkt_type != PACKET_HOST)
 619                 return -EINVAL;
 620         if (rt->rt_type == RTN_UNICAST) {
 621                 if (!opt->is_strictroute)
 622                         return 0;
 623                 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl(16<<24));
 624                 return -EINVAL;
 625         }
 626         if (rt->rt_type != RTN_LOCAL)
 627                 return -EINVAL;
 628
 629         for (srrptr = optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4) {
 630                 if (srrptr + 3 > srrspace) {
 631                         icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((opt->srr+2)<<24));
 632                         return -EINVAL;
 633                 }
 634                 memcpy(&nexthop, &optptr[srrptr-1], 4);
 635
 636                 orefdst = skb->_skb_refdst;
 637                 skb_dst_set(skb, NULL);
 638                 err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, skb->dev);
 639                 rt2 = skb_rtable(skb);
 640                 if (err || (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) {
 641                         skb_dst_drop(skb);
 642                         skb->_skb_refdst = orefdst;
 643                         return -EINVAL;
 644                 }
 645                 refdst_drop(orefdst);
 646                 if (rt2->rt_type != RTN_LOCAL)
 647                         break;
 648                 /* Superfast 8) loopback forward */
 649                 iph->daddr = nexthop;
 650                 opt->is_changed = 1;
 651         }
 652         if (srrptr <= srrspace) {
 653                 opt->srr_is_hit = 1;
 654                 opt->nexthop = nexthop;
 655                 opt->is_changed = 1;
 656         }
 657         return 0;
 658 }
 659 EXPORT_SYMBOL(ip_options_rcv_srr);