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 <asm/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 ip_options *dopt, struct sk_buff *skb, 90 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(dev_net(skb_dst(skb)->dev), 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 __be32 daddr = fib_compute_spec_dst(skb); 178 179 memcpy(&start[doffset-1], &daddr, 4); 180 dopt->faddr = faddr; 181 dptr[0] = start[0]; 182 dptr[1] = doffset+3; 183 dptr[2] = 4; 184 dptr += doffset+3; 185 dopt->srr = dopt->optlen + sizeof(struct iphdr); 186 dopt->optlen += doffset+3; 187 dopt->is_strictroute = sopt->is_strictroute; 188 } 189 } 190 if (sopt->cipso) { 191 optlen = sptr[sopt->cipso+1]; 192 dopt->cipso = dopt->optlen+sizeof(struct iphdr); 193 memcpy(dptr, sptr+sopt->cipso, optlen); 194 dptr += optlen; 195 dopt->optlen += optlen; 196 } 197 while (dopt->optlen & 3) { 198 *dptr++ = IPOPT_END; 199 dopt->optlen++; 200 } 201 return 0; 202 } 203 204 /* 205 * Options "fragmenting", just fill options not 206 * allowed in fragments with NOOPs. 207 * Simple and stupid 8), but the most efficient way. 208 */ 209 210 void ip_options_fragment(struct sk_buff *skb) 211 { 212 unsigned char *optptr = skb_network_header(skb) + sizeof(struct iphdr); 213 struct ip_options *opt = &(IPCB(skb)->opt); 214 int l = opt->optlen; 215 int optlen; 216 217 while (l > 0) { 218 switch (*optptr) { 219 case IPOPT_END: 220 return; 221 case IPOPT_NOOP: 222 l--; 223 optptr++; 224 continue; 225 } 226 optlen = optptr[1]; 227 if (optlen < 2 || optlen > l) 228 return; 229 if (!IPOPT_COPIED(*optptr)) 230 memset(optptr, IPOPT_NOOP, optlen); 231 l -= optlen; 232 optptr += optlen; 233 } 234 opt->ts = 0; 235 opt->rr = 0; 236 opt->rr_needaddr = 0; 237 opt->ts_needaddr = 0; 238 opt->ts_needtime = 0; 239 } 240 241 /* helper used by ip_options_compile() to call fib_compute_spec_dst() 242 * at most one time. 243 */ 244 static void spec_dst_fill(__be32 *spec_dst, struct sk_buff *skb) 245 { 246 if (*spec_dst == htonl(INADDR_ANY)) 247 *spec_dst = fib_compute_spec_dst(skb); 248 } 249 250 /* 251 * Verify options and fill pointers in struct options. 252 * Caller should clear *opt, and set opt->data. 253 * If opt == NULL, then skb->data should point to IP header. 254 */ 255 256 int ip_options_compile(struct net *net, 257 struct ip_options *opt, struct sk_buff *skb) 258 { 259 __be32 spec_dst = htonl(INADDR_ANY); 260 unsigned char *pp_ptr = NULL; 261 struct rtable *rt = NULL; 262 unsigned char *optptr; 263 unsigned char *iph; 264 int optlen, l; 265 266 if (skb) { 267 rt = skb_rtable(skb); 268 optptr = (unsigned char *)&(ip_hdr(skb)[1]); 269 } else 270 optptr = opt->__data; 271 iph = optptr - sizeof(struct iphdr); 272 273 for (l = opt->optlen; l > 0; ) { 274 switch (*optptr) { 275 case IPOPT_END: 276 for (optptr++, l--; l > 0; optptr++, l--) { 277 if (*optptr != IPOPT_END) { 278 *optptr = IPOPT_END; 279 opt->is_changed = 1; 280 } 281 } 282 goto eol; 283 case IPOPT_NOOP: 284 l--; 285 optptr++; 286 continue; 287 } 288 if (unlikely(l < 2)) { 289 pp_ptr = optptr; 290 goto error; 291 } 292 optlen = optptr[1]; 293 if (optlen < 2 || optlen > l) { 294 pp_ptr = optptr; 295 goto error; 296 } 297 switch (*optptr) { 298 case IPOPT_SSRR: 299 case IPOPT_LSRR: 300 if (optlen < 3) { 301 pp_ptr = optptr + 1; 302 goto error; 303 } 304 if (optptr[2] < 4) { 305 pp_ptr = optptr + 2; 306 goto error; 307 } 308 /* NB: cf RFC-1812 5.2.4.1 */ 309 if (opt->srr) { 310 pp_ptr = optptr; 311 goto error; 312 } 313 if (!skb) { 314 if (optptr[2] != 4 || optlen < 7 || ((optlen-3) & 3)) { 315 pp_ptr = optptr + 1; 316 goto error; 317 } 318 memcpy(&opt->faddr, &optptr[3], 4); 319 if (optlen > 7) 320 memmove(&optptr[3], &optptr[7], optlen-7); 321 } 322 opt->is_strictroute = (optptr[0] == IPOPT_SSRR); 323 opt->srr = optptr - iph; 324 break; 325 case IPOPT_RR: 326 if (opt->rr) { 327 pp_ptr = optptr; 328 goto error; 329 } 330 if (optlen < 3) { 331 pp_ptr = optptr + 1; 332 goto error; 333 } 334 if (optptr[2] < 4) { 335 pp_ptr = optptr + 2; 336 goto error; 337 } 338 if (optptr[2] <= optlen) { 339 if (optptr[2]+3 > optlen) { 340 pp_ptr = optptr + 2; 341 goto error; 342 } 343 if (rt) { 344 spec_dst_fill(&spec_dst, skb); 345 memcpy(&optptr[optptr[2]-1], &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 unsigned char *timeptr = NULL; 368 if (optptr[2]+3 > optlen) { 369 pp_ptr = optptr + 2; 370 goto error; 371 } 372 switch (optptr[3]&0xF) { 373 case IPOPT_TS_TSONLY: 374 if (skb) 375 timeptr = &optptr[optptr[2]-1]; 376 opt->ts_needtime = 1; 377 optptr[2] += 4; 378 break; 379 case IPOPT_TS_TSANDADDR: 380 if (optptr[2]+7 > optlen) { 381 pp_ptr = optptr + 2; 382 goto error; 383 } 384 if (rt) { 385 spec_dst_fill(&spec_dst, skb); 386 memcpy(&optptr[optptr[2]-1], &spec_dst, 4); 387 timeptr = &optptr[optptr[2]+3]; 388 } 389 opt->ts_needaddr = 1; 390 opt->ts_needtime = 1; 391 optptr[2] += 8; 392 break; 393 case IPOPT_TS_PRESPEC: 394 if (optptr[2]+7 > optlen) { 395 pp_ptr = optptr + 2; 396 goto error; 397 } 398 { 399 __be32 addr; 400 memcpy(&addr, &optptr[optptr[2]-1], 4); 401 if (inet_addr_type(net, addr) == RTN_UNICAST) 402 break; 403 if (skb) 404 timeptr = &optptr[optptr[2]+3]; 405 } 406 opt->ts_needtime = 1; 407 optptr[2] += 8; 408 break; 409 default: 410 if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) { 411 pp_ptr = optptr + 3; 412 goto error; 413 } 414 break; 415 } 416 if (timeptr) { 417 __be32 midtime; 418 419 midtime = inet_current_timestamp(); 420 memcpy(timeptr, &midtime, 4); 421 opt->is_changed = 1; 422 } 423 } else if ((optptr[3]&0xF) != IPOPT_TS_PRESPEC) { 424 unsigned int overflow = optptr[3]>>4; 425 if (overflow == 15) { 426 pp_ptr = optptr + 3; 427 goto error; 428 } 429 if (skb) { 430 optptr[3] = (optptr[3]&0xF)|((overflow+1)<<4); 431 opt->is_changed = 1; 432 } 433 } 434 opt->ts = optptr - iph; 435 break; 436 case IPOPT_RA: 437 if (optlen < 4) { 438 pp_ptr = optptr + 1; 439 goto error; 440 } 441 if (optptr[2] == 0 && optptr[3] == 0) 442 opt->router_alert = optptr - iph; 443 break; 444 case IPOPT_CIPSO: 445 if ((!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) || opt->cipso) { 446 pp_ptr = optptr; 447 goto error; 448 } 449 opt->cipso = optptr - iph; 450 if (cipso_v4_validate(skb, &optptr)) { 451 pp_ptr = optptr; 452 goto error; 453 } 454 break; 455 case IPOPT_SEC: 456 case IPOPT_SID: 457 default: 458 if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) { 459 pp_ptr = optptr; 460 goto error; 461 } 462 break; 463 } 464 l -= optlen; 465 optptr += optlen; 466 } 467 468 eol: 469 if (!pp_ptr) 470 return 0; 471 472 error: 473 if (skb) { 474 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((pp_ptr-iph)<<24)); 475 } 476 return -EINVAL; 477 } 478 EXPORT_SYMBOL(ip_options_compile); 479 480 /* 481 * Undo all the changes done by ip_options_compile(). 482 */ 483 484 void ip_options_undo(struct ip_options *opt) 485 { 486 if (opt->srr) { 487 unsigned char *optptr = opt->__data+opt->srr-sizeof(struct iphdr); 488 memmove(optptr+7, optptr+3, optptr[1]-7); 489 memcpy(optptr+3, &opt->faddr, 4); 490 } 491 if (opt->rr_needaddr) { 492 unsigned char *optptr = opt->__data+opt->rr-sizeof(struct iphdr); 493 optptr[2] -= 4; 494 memset(&optptr[optptr[2]-1], 0, 4); 495 } 496 if (opt->ts) { 497 unsigned char *optptr = opt->__data+opt->ts-sizeof(struct iphdr); 498 if (opt->ts_needtime) { 499 optptr[2] -= 4; 500 memset(&optptr[optptr[2]-1], 0, 4); 501 if ((optptr[3]&0xF) == IPOPT_TS_PRESPEC) 502 optptr[2] -= 4; 503 } 504 if (opt->ts_needaddr) { 505 optptr[2] -= 4; 506 memset(&optptr[optptr[2]-1], 0, 4); 507 } 508 } 509 } 510 511 static struct ip_options_rcu *ip_options_get_alloc(const int optlen) 512 { 513 return kzalloc(sizeof(struct ip_options_rcu) + ((optlen + 3) & ~3), 514 GFP_KERNEL); 515 } 516 517 static int ip_options_get_finish(struct net *net, struct ip_options_rcu **optp, 518 struct ip_options_rcu *opt, int optlen) 519 { 520 while (optlen & 3) 521 opt->opt.__data[optlen++] = IPOPT_END; 522 opt->opt.optlen = optlen; 523 if (optlen && ip_options_compile(net, &opt->opt, NULL)) { 524 kfree(opt); 525 return -EINVAL; 526 } 527 kfree(*optp); 528 *optp = opt; 529 return 0; 530 } 531 532 int ip_options_get_from_user(struct net *net, struct ip_options_rcu **optp, 533 unsigned char __user *data, int optlen) 534 { 535 struct ip_options_rcu *opt = ip_options_get_alloc(optlen); 536 537 if (!opt) 538 return -ENOMEM; 539 if (optlen && copy_from_user(opt->opt.__data, data, optlen)) { 540 kfree(opt); 541 return -EFAULT; 542 } 543 return ip_options_get_finish(net, optp, opt, optlen); 544 } 545 546 int ip_options_get(struct net *net, struct ip_options_rcu **optp, 547 unsigned char *data, int optlen) 548 { 549 struct ip_options_rcu *opt = ip_options_get_alloc(optlen); 550 551 if (!opt) 552 return -ENOMEM; 553 if (optlen) 554 memcpy(opt->opt.__data, data, optlen); 555 return ip_options_get_finish(net, optp, opt, optlen); 556 } 557 558 void ip_forward_options(struct sk_buff *skb) 559 { 560 struct ip_options *opt = &(IPCB(skb)->opt); 561 unsigned char *optptr; 562 struct rtable *rt = skb_rtable(skb); 563 unsigned char *raw = skb_network_header(skb); 564 565 if (opt->rr_needaddr) { 566 optptr = (unsigned char *)raw + opt->rr; 567 ip_rt_get_source(&optptr[optptr[2]-5], skb, rt); 568 opt->is_changed = 1; 569 } 570 if (opt->srr_is_hit) { 571 int srrptr, srrspace; 572 573 optptr = raw + opt->srr; 574 575 for ( srrptr = optptr[2], srrspace = optptr[1]; 576 srrptr <= srrspace; 577 srrptr += 4 578 ) { 579 if (srrptr + 3 > srrspace) 580 break; 581 if (memcmp(&opt->nexthop, &optptr[srrptr-1], 4) == 0) 582 break; 583 } 584 if (srrptr + 3 <= srrspace) { 585 opt->is_changed = 1; 586 ip_hdr(skb)->daddr = opt->nexthop; 587 ip_rt_get_source(&optptr[srrptr-1], skb, rt); 588 optptr[2] = srrptr+4; 589 } else { 590 net_crit_ratelimited("%s(): Argh! Destination lost!\n", 591 __func__); 592 } 593 if (opt->ts_needaddr) { 594 optptr = raw + opt->ts; 595 ip_rt_get_source(&optptr[optptr[2]-9], skb, 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 = skb_rtable(skb); 613 struct rtable *rt2; 614 unsigned long orefdst; 615 int err; 616 617 if (!rt) 618 return 0; 619 620 if (skb->pkt_type != PACKET_HOST) 621 return -EINVAL; 622 if (rt->rt_type == RTN_UNICAST) { 623 if (!opt->is_strictroute) 624 return 0; 625 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl(16<<24)); 626 return -EINVAL; 627 } 628 if (rt->rt_type != RTN_LOCAL) 629 return -EINVAL; 630 631 for (srrptr = optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4) { 632 if (srrptr + 3 > srrspace) { 633 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((opt->srr+2)<<24)); 634 return -EINVAL; 635 } 636 memcpy(&nexthop, &optptr[srrptr-1], 4); 637 638 orefdst = skb->_skb_refdst; 639 skb_dst_set(skb, NULL); 640 err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, skb->dev); 641 rt2 = skb_rtable(skb); 642 if (err || (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) { 643 skb_dst_drop(skb); 644 skb->_skb_refdst = orefdst; 645 return -EINVAL; 646 } 647 refdst_drop(orefdst); 648 if (rt2->rt_type != RTN_LOCAL) 649 break; 650 /* Superfast 8) loopback forward */ 651 iph->daddr = nexthop; 652 opt->is_changed = 1; 653 } 654 if (srrptr <= srrspace) { 655 opt->srr_is_hit = 1; 656 opt->nexthop = nexthop; 657 opt->is_changed = 1; 658 } 659 return 0; 660 } 661 EXPORT_SYMBOL(ip_options_rcv_srr); 662