net/ipv4/ip_options.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              The options processing module for ip.c
   7  *
   8  * Version:     $Id: ip_options.c,v 1.21 2001/09/01 00:31:50 davem Exp $
   9  *
  10  * Authors:     A.N.Kuznetsov
  11  *
  12  */
  13
  14 #include <linux/capability.h>
  15 #include <linux/module.h>
  16 #include <linux/types.h>
  17 #include <asm/uaccess.h>
  18 #include <linux/skbuff.h>
  19 #include <linux/ip.h>
  20 #include <linux/icmp.h>
  21 #include <linux/netdevice.h>
  22 #include <linux/rtnetlink.h>
  23 #include <net/sock.h>
  24 #include <net/ip.h>
  25 #include <net/icmp.h>
  26 #include <net/route.h>
  27 #include <net/cipso_ipv4.h>
  28
  29 /*
  30  * Write options to IP header, record destination address to
  31  * source route option, address of outgoing interface
  32  * (we should already know it, so that this  function is allowed be
  33  * called only after routing decision) and timestamp,
  34  * if we originate this datagram.
  35  *
  36  * daddr is real destination address, next hop is recorded in IP header.
  37  * saddr is address of outgoing interface.
  38  */
  39
  40 void ip_options_build(struct sk_buff * skb, struct ip_options * opt,
  41                             __be32 daddr, struct rtable *rt, int is_frag)
  42 {
  43         unsigned char *iph = skb_network_header(skb);
  44
  45         memcpy(&(IPCB(skb)->opt), opt, sizeof(struct ip_options));
  46         memcpy(iph+sizeof(struct iphdr), opt->__data, opt->optlen);
  47         opt = &(IPCB(skb)->opt);
  48         opt->is_data = 0;
  49
  50         if (opt->srr)
  51                 memcpy(iph+opt->srr+iph[opt->srr+1]-4, &daddr, 4);
  52
  53         if (!is_frag) {
  54                 if (opt->rr_needaddr)
  55                         ip_rt_get_source(iph+opt->rr+iph[opt->rr+2]-5, rt);
  56                 if (opt->ts_needaddr)
  57                         ip_rt_get_source(iph+opt->ts+iph[opt->ts+2]-9, rt);
  58                 if (opt->ts_needtime) {
  59                         struct timeval tv;
  60                         __be32 midtime;
  61                         do_gettimeofday(&tv);
  62                         midtime = htonl((tv.tv_sec % 86400) * 1000 + tv.tv_usec / 1000);
  63                         memcpy(iph+opt->ts+iph[opt->ts+2]-5, &midtime, 4);
  64                 }
  65                 return;
  66         }
  67         if (opt->rr) {
  68                 memset(iph+opt->rr, IPOPT_NOP, iph[opt->rr+1]);
  69                 opt->rr = 0;
  70                 opt->rr_needaddr = 0;
  71         }
  72         if (opt->ts) {
  73                 memset(iph+opt->ts, IPOPT_NOP, iph[opt->ts+1]);
  74                 opt->ts = 0;
  75                 opt->ts_needaddr = opt->ts_needtime = 0;
  76         }
  77 }
  78
  79 /*
  80  * Provided (sopt, skb) points to received options,
  81  * build in dopt compiled option set appropriate for answering.
  82  * i.e. invert SRR option, copy anothers,
  83  * and grab room in RR/TS options.
  84  *
  85  * NOTE: dopt cannot point to skb.
  86  */
  87
  88 int ip_options_echo(struct ip_options * dopt, struct sk_buff * skb)
  89 {
  90         struct ip_options *sopt;
  91         unsigned char *sptr, *dptr;
  92         int soffset, doffset;
  93         int     optlen;
  94         __be32  daddr;
  95
  96         memset(dopt, 0, sizeof(struct ip_options));
  97
  98         dopt->is_data = 1;
  99
 100         sopt = &(IPCB(skb)->opt);
 101
 102         if (sopt->optlen == 0) {
 103                 dopt->optlen = 0;
 104                 return 0;
 105         }
 106
 107         sptr = skb_network_header(skb);
 108         dptr = dopt->__data;
 109
 110         if (skb->dst)
 111                 daddr = ((struct rtable*)skb->dst)->rt_spec_dst;
 112         else
 113                 daddr = ip_hdr(skb)->daddr;
 114
 115         if (sopt->rr) {
 116                 optlen  = sptr[sopt->rr+1];
 117                 soffset = sptr[sopt->rr+2];
 118                 dopt->rr = dopt->optlen + sizeof(struct iphdr);
 119                 memcpy(dptr, sptr+sopt->rr, optlen);
 120                 if (sopt->rr_needaddr && soffset <= optlen) {
 121                         if (soffset + 3 > optlen)
 122                                 return -EINVAL;
 123                         dptr[2] = soffset + 4;
 124                         dopt->rr_needaddr = 1;
 125                 }
 126                 dptr += optlen;
 127                 dopt->optlen += optlen;
 128         }
 129         if (sopt->ts) {
 130                 optlen = sptr[sopt->ts+1];
 131                 soffset = sptr[sopt->ts+2];
 132                 dopt->ts = dopt->optlen + sizeof(struct iphdr);
 133                 memcpy(dptr, sptr+sopt->ts, optlen);
 134                 if (soffset <= optlen) {
 135                         if (sopt->ts_needaddr) {
 136                                 if (soffset + 3 > optlen)
 137                                         return -EINVAL;
 138                                 dopt->ts_needaddr = 1;
 139                                 soffset += 4;
 140                         }
 141                         if (sopt->ts_needtime) {
 142                                 if (soffset + 3 > optlen)
 143                                         return -EINVAL;
 144                                 if ((dptr[3]&0xF) != IPOPT_TS_PRESPEC) {
 145                                         dopt->ts_needtime = 1;
 146                                         soffset += 4;
 147                                 } else {
 148                                         dopt->ts_needtime = 0;
 149
 150                                         if (soffset + 8 <= optlen) {
 151                                                 __be32 addr;
 152
 153                                                 memcpy(&addr, sptr+soffset-1, 4);
 154                                                 if (inet_addr_type(addr) != RTN_LOCAL) {
 155                                                         dopt->ts_needtime = 1;
 156                                                         soffset += 8;
 157                                                 }
 158                                         }
 159                                 }
 160                         }
 161                         dptr[2] = soffset;
 162                 }
 163                 dptr += optlen;
 164                 dopt->optlen += optlen;
 165         }
 166         if (sopt->srr) {
 167                 unsigned char * start = sptr+sopt->srr;
 168                 __be32 faddr;
 169
 170                 optlen  = start[1];
 171                 soffset = start[2];
 172                 doffset = 0;
 173                 if (soffset > optlen)
 174                         soffset = optlen + 1;
 175                 soffset -= 4;
 176                 if (soffset > 3) {
 177                         memcpy(&faddr, &start[soffset-1], 4);
 178                         for (soffset-=4, doffset=4; soffset > 3; soffset-=4, doffset+=4)
 179                                 memcpy(&dptr[doffset-1], &start[soffset-1], 4);
 180                         /*
 181                          * RFC1812 requires to fix illegal source routes.
 182                          */
 183                         if (memcmp(&ip_hdr(skb)->saddr,
 184                                    &start[soffset + 3], 4) == 0)
 185                                 doffset -= 4;
 186                 }
 187                 if (doffset > 3) {
 188                         memcpy(&start[doffset-1], &daddr, 4);
 189                         dopt->faddr = faddr;
 190                         dptr[0] = start[0];
 191                         dptr[1] = doffset+3;
 192                         dptr[2] = 4;
 193                         dptr += doffset+3;
 194                         dopt->srr = dopt->optlen + sizeof(struct iphdr);
 195                         dopt->optlen += doffset+3;
 196                         dopt->is_strictroute = sopt->is_strictroute;
 197                 }
 198         }
 199         if (sopt->cipso) {
 200                 optlen  = sptr[sopt->cipso+1];
 201                 dopt->cipso = dopt->optlen+sizeof(struct iphdr);
 202                 memcpy(dptr, sptr+sopt->cipso, optlen);
 203                 dptr += optlen;
 204                 dopt->optlen += optlen;
 205         }
 206         while (dopt->optlen & 3) {
 207                 *dptr++ = IPOPT_END;
 208                 dopt->optlen++;
 209         }
 210         return 0;
 211 }
 212
 213 /*
 214  *      Options "fragmenting", just fill options not
 215  *      allowed in fragments with NOOPs.
 216  *      Simple and stupid 8), but the most efficient way.
 217  */
 218
 219 void ip_options_fragment(struct sk_buff * skb)
 220 {
 221         unsigned char *optptr = skb_network_header(skb) + sizeof(struct iphdr);
 222         struct ip_options * opt = &(IPCB(skb)->opt);
 223         int  l = opt->optlen;
 224         int  optlen;
 225
 226         while (l > 0) {
 227                 switch (*optptr) {
 228                 case IPOPT_END:
 229                         return;
 230                 case IPOPT_NOOP:
 231                         l--;
 232                         optptr++;
 233                         continue;
 234                 }
 235                 optlen = optptr[1];
 236                 if (optlen<2 || optlen>l)
 237                   return;
 238                 if (!IPOPT_COPIED(*optptr))
 239                         memset(optptr, IPOPT_NOOP, optlen);
 240                 l -= optlen;
 241                 optptr += optlen;
 242         }
 243         opt->ts = 0;
 244         opt->rr = 0;
 245         opt->rr_needaddr = 0;
 246         opt->ts_needaddr = 0;
 247         opt->ts_needtime = 0;
 248         return;
 249 }
 250
 251 /*
 252  * Verify options and fill pointers in struct options.
 253  * Caller should clear *opt, and set opt->data.
 254  * If opt == NULL, then skb->data should point to IP header.
 255  */
 256
 257 int ip_options_compile(struct ip_options * opt, struct sk_buff * skb)
 258 {
 259         int l;
 260         unsigned char * iph;
 261         unsigned char * optptr;
 262         int optlen;
 263         unsigned char * pp_ptr = NULL;
 264         struct rtable *rt = skb ? (struct rtable*)skb->dst : NULL;
 265
 266         if (!opt) {
 267                 opt = &(IPCB(skb)->opt);
 268                 iph = skb_network_header(skb);
 269                 opt->optlen = ((struct iphdr *)iph)->ihl*4 - sizeof(struct iphdr);
 270                 optptr = iph + sizeof(struct iphdr);
 271                 opt->is_data = 0;
 272         } else {
 273                 optptr = opt->is_data ? opt->__data :
 274                                         (unsigned char *)&(ip_hdr(skb)[1]);
 275                 iph = optptr - sizeof(struct iphdr);
 276         }
 277
 278         for (l = opt->optlen; l > 0; ) {
 279                 switch (*optptr) {
 280                       case IPOPT_END:
 281                         for (optptr++, l--; l>0; optptr++, l--) {
 282                                 if (*optptr != IPOPT_END) {
 283                                         *optptr = IPOPT_END;
 284                                         opt->is_changed = 1;
 285                                 }
 286                         }
 287                         goto eol;
 288                       case IPOPT_NOOP:
 289                         l--;
 290                         optptr++;
 291                         continue;
 292                 }
 293                 optlen = optptr[1];
 294                 if (optlen<2 || optlen>l) {
 295                         pp_ptr = optptr;
 296                         goto error;
 297                 }
 298                 switch (*optptr) {
 299                       case IPOPT_SSRR:
 300                       case IPOPT_LSRR:
 301                         if (optlen < 3) {
 302                                 pp_ptr = optptr + 1;
 303                                 goto error;
 304                         }
 305                         if (optptr[2] < 4) {
 306                                 pp_ptr = optptr + 2;
 307                                 goto error;
 308                         }
 309                         /* NB: cf RFC-1812 5.2.4.1 */
 310                         if (opt->srr) {
 311                                 pp_ptr = optptr;
 312                                 goto error;
 313                         }
 314                         if (!skb) {
 315                                 if (optptr[2] != 4 || optlen < 7 || ((optlen-3) & 3)) {
 316                                         pp_ptr = optptr + 1;
 317                                         goto error;
 318                                 }
 319                                 memcpy(&opt->faddr, &optptr[3], 4);
 320                                 if (optlen > 7)
 321                                         memmove(&optptr[3], &optptr[7], optlen-7);
 322                         }
 323                         opt->is_strictroute = (optptr[0] == IPOPT_SSRR);
 324                         opt->srr = optptr - iph;
 325                         break;
 326                       case IPOPT_RR:
 327                         if (opt->rr) {
 328                                 pp_ptr = optptr;
 329                                 goto error;
 330                         }
 331                         if (optlen < 3) {
 332                                 pp_ptr = optptr + 1;
 333                                 goto error;
 334                         }
 335                         if (optptr[2] < 4) {
 336                                 pp_ptr = optptr + 2;
 337                                 goto error;
 338                         }
 339                         if (optptr[2] <= optlen) {
 340                                 if (optptr[2]+3 > optlen) {
 341                                         pp_ptr = optptr + 2;
 342                                         goto error;
 343                                 }
 344                                 if (skb) {
 345                                         memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
 346                                         opt->is_changed = 1;
 347                                 }
 348                                 optptr[2] += 4;
 349                                 opt->rr_needaddr = 1;
 350                         }
 351                         opt->rr = optptr - iph;
 352                         break;
 353                       case IPOPT_TIMESTAMP:
 354                         if (opt->ts) {
 355                                 pp_ptr = optptr;
 356                                 goto error;
 357                         }
 358                         if (optlen < 4) {
 359                                 pp_ptr = optptr + 1;
 360                                 goto error;
 361                         }
 362                         if (optptr[2] < 5) {
 363                                 pp_ptr = optptr + 2;
 364                                 goto error;
 365                         }
 366                         if (optptr[2] <= optlen) {
 367                                 __be32 *timeptr = NULL;
 368                                 if (optptr[2]+3 > optptr[1]) {
 369                                         pp_ptr = optptr + 2;
 370                                         goto error;
 371                                 }
 372                                 switch (optptr[3]&0xF) {
 373                                       case IPOPT_TS_TSONLY:
 374                                         opt->ts = optptr - iph;
 375                                         if (skb)
 376                                                 timeptr = (__be32*)&optptr[optptr[2]-1];
 377                                         opt->ts_needtime = 1;
 378                                         optptr[2] += 4;
 379                                         break;
 380                                       case IPOPT_TS_TSANDADDR:
 381                                         if (optptr[2]+7 > optptr[1]) {
 382                                                 pp_ptr = optptr + 2;
 383                                                 goto error;
 384                                         }
 385                                         opt->ts = optptr - iph;
 386                                         if (skb) {
 387                                                 memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
 388                                                 timeptr = (__be32*)&optptr[optptr[2]+3];
 389                                         }
 390                                         opt->ts_needaddr = 1;
 391                                         opt->ts_needtime = 1;
 392                                         optptr[2] += 8;
 393                                         break;
 394                                       case IPOPT_TS_PRESPEC:
 395                                         if (optptr[2]+7 > optptr[1]) {
 396                                                 pp_ptr = optptr + 2;
 397                                                 goto error;
 398                                         }
 399                                         opt->ts = optptr - iph;
 400                                         {
 401                                                 __be32 addr;
 402                                                 memcpy(&addr, &optptr[optptr[2]-1], 4);
 403                                                 if (inet_addr_type(addr) == RTN_UNICAST)
 404                                                         break;
 405                                                 if (skb)
 406                                                         timeptr = (__be32*)&optptr[optptr[2]+3];
 407                                         }
 408                                         opt->ts_needtime = 1;
 409                                         optptr[2] += 8;
 410                                         break;
 411                                       default:
 412                                         if (!skb && !capable(CAP_NET_RAW)) {
 413                                                 pp_ptr = optptr + 3;
 414                                                 goto error;
 415                                         }
 416                                         break;
 417                                 }
 418                                 if (timeptr) {
 419                                         struct timeval tv;
 420                                         __be32  midtime;
 421                                         do_gettimeofday(&tv);
 422                                         midtime = htonl((tv.tv_sec % 86400) * 1000 + tv.tv_usec / 1000);
 423                                         memcpy(timeptr, &midtime, sizeof(__be32));
 424                                         opt->is_changed = 1;
 425                                 }
 426                         } else {
 427                                 unsigned overflow = optptr[3]>>4;
 428                                 if (overflow == 15) {
 429                                         pp_ptr = optptr + 3;
 430                                         goto error;
 431                                 }
 432                                 opt->ts = optptr - iph;
 433                                 if (skb) {
 434                                         optptr[3] = (optptr[3]&0xF)|((overflow+1)<<4);
 435                                         opt->is_changed = 1;
 436                                 }
 437                         }
 438                         break;
 439                       case IPOPT_RA:
 440                         if (optlen < 4) {
 441                                 pp_ptr = optptr + 1;
 442                                 goto error;
 443                         }
 444                         if (optptr[2] == 0 && optptr[3] == 0)
 445                                 opt->router_alert = optptr - iph;
 446                         break;
 447                       case IPOPT_CIPSO:
 448                         if ((!skb && !capable(CAP_NET_RAW)) || opt->cipso) {
 449                                 pp_ptr = optptr;
 450                                 goto error;
 451                         }
 452                         opt->cipso = optptr - iph;
 453                         if (cipso_v4_validate(&optptr)) {
 454                                 pp_ptr = optptr;
 455                                 goto error;
 456                         }
 457                         break;
 458                       case IPOPT_SEC:
 459                       case IPOPT_SID:
 460                       default:
 461                         if (!skb && !capable(CAP_NET_RAW)) {
 462                                 pp_ptr = optptr;
 463                                 goto error;
 464                         }
 465                         break;
 466                 }
 467                 l -= optlen;
 468                 optptr += optlen;
 469         }
 470
 471 eol:
 472         if (!pp_ptr)
 473                 return 0;
 474
 475 error:
 476         if (skb) {
 477                 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((pp_ptr-iph)<<24));
 478         }
 479         return -EINVAL;
 480 }
 481
 482
 483 /*
 484  *      Undo all the changes done by ip_options_compile().
 485  */
 486
 487 void ip_options_undo(struct ip_options * opt)
 488 {
 489         if (opt->srr) {
 490                 unsigned  char * optptr = opt->__data+opt->srr-sizeof(struct  iphdr);
 491                 memmove(optptr+7, optptr+3, optptr[1]-7);
 492                 memcpy(optptr+3, &opt->faddr, 4);
 493         }
 494         if (opt->rr_needaddr) {
 495                 unsigned  char * optptr = opt->__data+opt->rr-sizeof(struct  iphdr);
 496                 optptr[2] -= 4;
 497                 memset(&optptr[optptr[2]-1], 0, 4);
 498         }
 499         if (opt->ts) {
 500                 unsigned  char * optptr = opt->__data+opt->ts-sizeof(struct  iphdr);
 501                 if (opt->ts_needtime) {
 502                         optptr[2] -= 4;
 503                         memset(&optptr[optptr[2]-1], 0, 4);
 504                         if ((optptr[3]&0xF) == IPOPT_TS_PRESPEC)
 505                                 optptr[2] -= 4;
 506                 }
 507                 if (opt->ts_needaddr) {
 508                         optptr[2] -= 4;
 509                         memset(&optptr[optptr[2]-1], 0, 4);
 510                 }
 511         }
 512 }
 513
 514 static struct ip_options *ip_options_get_alloc(const int optlen)
 515 {
 516         return kzalloc(sizeof(struct ip_options) + ((optlen + 3) & ~3),
 517                        GFP_KERNEL);
 518 }
 519
 520 static int ip_options_get_finish(struct ip_options **optp,
 521                                  struct ip_options *opt, int optlen)
 522 {
 523         while (optlen & 3)
 524                 opt->__data[optlen++] = IPOPT_END;
 525         opt->optlen = optlen;
 526         opt->is_data = 1;
 527         if (optlen && ip_options_compile(opt, NULL)) {
 528                 kfree(opt);
 529                 return -EINVAL;
 530         }
 531         kfree(*optp);
 532         *optp = opt;
 533         return 0;
 534 }
 535
 536 int ip_options_get_from_user(struct ip_options **optp, unsigned char __user *data, int optlen)
 537 {
 538         struct ip_options *opt = ip_options_get_alloc(optlen);
 539
 540         if (!opt)
 541                 return -ENOMEM;
 542         if (optlen && copy_from_user(opt->__data, data, optlen)) {
 543                 kfree(opt);
 544                 return -EFAULT;
 545         }
 546         return ip_options_get_finish(optp, opt, optlen);
 547 }
 548
 549 int ip_options_get(struct ip_options **optp, unsigned char *data, int optlen)
 550 {
 551         struct ip_options *opt = ip_options_get_alloc(optlen);
 552
 553         if (!opt)
 554                 return -ENOMEM;
 555         if (optlen)
 556                 memcpy(opt->__data, data, optlen);
 557         return ip_options_get_finish(optp, opt, optlen);
 558 }
 559
 560 void ip_forward_options(struct sk_buff *skb)
 561 {
 562         struct   ip_options * opt       = &(IPCB(skb)->opt);
 563         unsigned char * optptr;
 564         struct rtable *rt = (struct rtable*)skb->dst;
 565         unsigned char *raw = skb_network_header(skb);
 566
 567         if (opt->rr_needaddr) {
 568                 optptr = (unsigned char *)raw + opt->rr;
 569                 ip_rt_get_source(&optptr[optptr[2]-5], rt);
 570                 opt->is_changed = 1;
 571         }
 572         if (opt->srr_is_hit) {
 573                 int srrptr, srrspace;
 574
 575                 optptr = raw + opt->srr;
 576
 577                 for ( srrptr=optptr[2], srrspace = optptr[1];
 578                      srrptr <= srrspace;
 579                      srrptr += 4
 580                      ) {
 581                         if (srrptr + 3 > srrspace)
 582                                 break;
 583                         if (memcmp(&rt->rt_dst, &optptr[srrptr-1], 4) == 0)
 584                                 break;
 585                 }
 586                 if (srrptr + 3 <= srrspace) {
 587                         opt->is_changed = 1;
 588                         ip_rt_get_source(&optptr[srrptr-1], rt);
 589                         ip_hdr(skb)->daddr = rt->rt_dst;
 590                         optptr[2] = srrptr+4;
 591                 } else if (net_ratelimit())
 592                         printk(KERN_CRIT "ip_forward(): Argh! Destination lost!\n");
 593                 if (opt->ts_needaddr) {
 594                         optptr = raw + opt->ts;
 595                         ip_rt_get_source(&optptr[optptr[2]-9], rt);
 596                         opt->is_changed = 1;
 597                 }
 598         }
 599         if (opt->is_changed) {
 600                 opt->is_changed = 0;
 601                 ip_send_check(ip_hdr(skb));
 602         }
 603 }
 604
 605 int ip_options_rcv_srr(struct sk_buff *skb)
 606 {
 607         struct ip_options *opt = &(IPCB(skb)->opt);
 608         int srrspace, srrptr;
 609         __be32 nexthop;
 610         struct iphdr *iph = ip_hdr(skb);
 611         unsigned char *optptr = skb_network_header(skb) + opt->srr;
 612         struct rtable *rt = (struct rtable*)skb->dst;
 613         struct rtable *rt2;
 614         int err;
 615
 616         if (!opt->srr)
 617                 return 0;
 618
 619         if (skb->pkt_type != PACKET_HOST)
 620                 return -EINVAL;
 621         if (rt->rt_type == RTN_UNICAST) {
 622                 if (!opt->is_strictroute)
 623                         return 0;
 624                 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl(16<<24));
 625                 return -EINVAL;
 626         }
 627         if (rt->rt_type != RTN_LOCAL)
 628                 return -EINVAL;
 629
 630         for (srrptr=optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4) {
 631                 if (srrptr + 3 > srrspace) {
 632                         icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((opt->srr+2)<<24));
 633                         return -EINVAL;
 634                 }
 635                 memcpy(&nexthop, &optptr[srrptr-1], 4);
 636
 637                 rt = (struct rtable*)skb->dst;
 638                 skb->dst = NULL;
 639                 err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, skb->dev);
 640                 rt2 = (struct rtable*)skb->dst;
 641                 if (err || (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) {
 642                         ip_rt_put(rt2);
 643                         skb->dst = &rt->u.dst;
 644                         return -EINVAL;
 645                 }
 646                 ip_rt_put(rt);
 647                 if (rt2->rt_type != RTN_LOCAL)
 648                         break;
 649                 /* Superfast 8) loopback forward */
 650                 memcpy(&iph->daddr, &optptr[srrptr-1], 4);
 651                 opt->is_changed = 1;
 652         }
 653         if (srrptr <= srrspace) {
 654                 opt->srr_is_hit = 1;
 655                 opt->is_changed = 1;
 656         }
 657         return 0;
 658 }