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