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