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 struct timespec tv; 62 __be32 midtime; 63 getnstimeofday(&tv); 64 midtime = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + tv.tv_nsec / NSEC_PER_MSEC); 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 ip_options *dopt, struct sk_buff *skb) 91 { 92 const struct ip_options *sopt; 93 unsigned char *sptr, *dptr; 94 int soffset, doffset; 95 int optlen; 96 97 memset(dopt, 0, sizeof(struct ip_options)); 98 99 sopt = &(IPCB(skb)->opt); 100 101 if (sopt->optlen == 0) 102 return 0; 103 104 sptr = skb_network_header(skb); 105 dptr = dopt->__data; 106 107 if (sopt->rr) { 108 optlen = sptr[sopt->rr+1]; 109 soffset = sptr[sopt->rr+2]; 110 dopt->rr = dopt->optlen + sizeof(struct iphdr); 111 memcpy(dptr, sptr+sopt->rr, optlen); 112 if (sopt->rr_needaddr && soffset <= optlen) { 113 if (soffset + 3 > optlen) 114 return -EINVAL; 115 dptr[2] = soffset + 4; 116 dopt->rr_needaddr = 1; 117 } 118 dptr += optlen; 119 dopt->optlen += optlen; 120 } 121 if (sopt->ts) { 122 optlen = sptr[sopt->ts+1]; 123 soffset = sptr[sopt->ts+2]; 124 dopt->ts = dopt->optlen + sizeof(struct iphdr); 125 memcpy(dptr, sptr+sopt->ts, optlen); 126 if (soffset <= optlen) { 127 if (sopt->ts_needaddr) { 128 if (soffset + 3 > optlen) 129 return -EINVAL; 130 dopt->ts_needaddr = 1; 131 soffset += 4; 132 } 133 if (sopt->ts_needtime) { 134 if (soffset + 3 > optlen) 135 return -EINVAL; 136 if ((dptr[3]&0xF) != IPOPT_TS_PRESPEC) { 137 dopt->ts_needtime = 1; 138 soffset += 4; 139 } else { 140 dopt->ts_needtime = 0; 141 142 if (soffset + 7 <= optlen) { 143 __be32 addr; 144 145 memcpy(&addr, dptr+soffset-1, 4); 146 if (inet_addr_type(dev_net(skb_dst(skb)->dev), addr) != RTN_UNICAST) { 147 dopt->ts_needtime = 1; 148 soffset += 8; 149 } 150 } 151 } 152 } 153 dptr[2] = soffset; 154 } 155 dptr += optlen; 156 dopt->optlen += optlen; 157 } 158 if (sopt->srr) { 159 unsigned char *start = sptr+sopt->srr; 160 __be32 faddr; 161 162 optlen = start[1]; 163 soffset = start[2]; 164 doffset = 0; 165 if (soffset > optlen) 166 soffset = optlen + 1; 167 soffset -= 4; 168 if (soffset > 3) { 169 memcpy(&faddr, &start[soffset-1], 4); 170 for (soffset -= 4, doffset = 4; soffset > 3; soffset -= 4, doffset += 4) 171 memcpy(&dptr[doffset-1], &start[soffset-1], 4); 172 /* 173 * RFC1812 requires to fix illegal source routes. 174 */ 175 if (memcmp(&ip_hdr(skb)->saddr, 176 &start[soffset + 3], 4) == 0) 177 doffset -= 4; 178 } 179 if (doffset > 3) { 180 __be32 daddr = fib_compute_spec_dst(skb); 181 182 memcpy(&start[doffset-1], &daddr, 4); 183 dopt->faddr = faddr; 184 dptr[0] = start[0]; 185 dptr[1] = doffset+3; 186 dptr[2] = 4; 187 dptr += doffset+3; 188 dopt->srr = dopt->optlen + sizeof(struct iphdr); 189 dopt->optlen += doffset+3; 190 dopt->is_strictroute = sopt->is_strictroute; 191 } 192 } 193 if (sopt->cipso) { 194 optlen = sptr[sopt->cipso+1]; 195 dopt->cipso = dopt->optlen+sizeof(struct iphdr); 196 memcpy(dptr, sptr+sopt->cipso, optlen); 197 dptr += optlen; 198 dopt->optlen += optlen; 199 } 200 while (dopt->optlen & 3) { 201 *dptr++ = IPOPT_END; 202 dopt->optlen++; 203 } 204 return 0; 205 } 206 207 /* 208 * Options "fragmenting", just fill options not 209 * allowed in fragments with NOOPs. 210 * Simple and stupid 8), but the most efficient way. 211 */ 212 213 void ip_options_fragment(struct sk_buff *skb) 214 { 215 unsigned char *optptr = skb_network_header(skb) + sizeof(struct iphdr); 216 struct ip_options *opt = &(IPCB(skb)->opt); 217 int l = opt->optlen; 218 int optlen; 219 220 while (l > 0) { 221 switch (*optptr) { 222 case IPOPT_END: 223 return; 224 case IPOPT_NOOP: 225 l--; 226 optptr++; 227 continue; 228 } 229 optlen = optptr[1]; 230 if (optlen < 2 || optlen > l) 231 return; 232 if (!IPOPT_COPIED(*optptr)) 233 memset(optptr, IPOPT_NOOP, optlen); 234 l -= optlen; 235 optptr += optlen; 236 } 237 opt->ts = 0; 238 opt->rr = 0; 239 opt->rr_needaddr = 0; 240 opt->ts_needaddr = 0; 241 opt->ts_needtime = 0; 242 } 243 244 /* helper used by ip_options_compile() to call fib_compute_spec_dst() 245 * at most one time. 246 */ 247 static void spec_dst_fill(__be32 *spec_dst, struct sk_buff *skb) 248 { 249 if (*spec_dst == htonl(INADDR_ANY)) 250 *spec_dst = fib_compute_spec_dst(skb); 251 } 252 253 /* 254 * Verify options and fill pointers in struct options. 255 * Caller should clear *opt, and set opt->data. 256 * If opt == NULL, then skb->data should point to IP header. 257 */ 258 259 int ip_options_compile(struct net *net, 260 struct ip_options *opt, struct sk_buff *skb) 261 { 262 __be32 spec_dst = htonl(INADDR_ANY); 263 unsigned char *pp_ptr = NULL; 264 struct rtable *rt = NULL; 265 unsigned char *optptr; 266 unsigned char *iph; 267 int optlen, l; 268 269 if (skb != NULL) { 270 rt = skb_rtable(skb); 271 optptr = (unsigned char *)&(ip_hdr(skb)[1]); 272 } else 273 optptr = opt->__data; 274 iph = optptr - sizeof(struct iphdr); 275 276 for (l = opt->optlen; l > 0; ) { 277 switch (*optptr) { 278 case IPOPT_END: 279 for (optptr++, l--; l > 0; optptr++, l--) { 280 if (*optptr != IPOPT_END) { 281 *optptr = IPOPT_END; 282 opt->is_changed = 1; 283 } 284 } 285 goto eol; 286 case IPOPT_NOOP: 287 l--; 288 optptr++; 289 continue; 290 } 291 optlen = optptr[1]; 292 if (optlen < 2 || optlen > l) { 293 pp_ptr = optptr; 294 goto error; 295 } 296 switch (*optptr) { 297 case IPOPT_SSRR: 298 case IPOPT_LSRR: 299 if (optlen < 3) { 300 pp_ptr = optptr + 1; 301 goto error; 302 } 303 if (optptr[2] < 4) { 304 pp_ptr = optptr + 2; 305 goto error; 306 } 307 /* NB: cf RFC-1812 5.2.4.1 */ 308 if (opt->srr) { 309 pp_ptr = optptr; 310 goto error; 311 } 312 if (!skb) { 313 if (optptr[2] != 4 || optlen < 7 || ((optlen-3) & 3)) { 314 pp_ptr = optptr + 1; 315 goto error; 316 } 317 memcpy(&opt->faddr, &optptr[3], 4); 318 if (optlen > 7) 319 memmove(&optptr[3], &optptr[7], optlen-7); 320 } 321 opt->is_strictroute = (optptr[0] == IPOPT_SSRR); 322 opt->srr = optptr - iph; 323 break; 324 case IPOPT_RR: 325 if (opt->rr) { 326 pp_ptr = optptr; 327 goto error; 328 } 329 if (optlen < 3) { 330 pp_ptr = optptr + 1; 331 goto error; 332 } 333 if (optptr[2] < 4) { 334 pp_ptr = optptr + 2; 335 goto error; 336 } 337 if (optptr[2] <= optlen) { 338 if (optptr[2]+3 > optlen) { 339 pp_ptr = optptr + 2; 340 goto error; 341 } 342 if (rt) { 343 spec_dst_fill(&spec_dst, skb); 344 memcpy(&optptr[optptr[2]-1], &spec_dst, 4); 345 opt->is_changed = 1; 346 } 347 optptr[2] += 4; 348 opt->rr_needaddr = 1; 349 } 350 opt->rr = optptr - iph; 351 break; 352 case IPOPT_TIMESTAMP: 353 if (opt->ts) { 354 pp_ptr = optptr; 355 goto error; 356 } 357 if (optlen < 4) { 358 pp_ptr = optptr + 1; 359 goto error; 360 } 361 if (optptr[2] < 5) { 362 pp_ptr = optptr + 2; 363 goto error; 364 } 365 if (optptr[2] <= optlen) { 366 unsigned char *timeptr = NULL; 367 if (optptr[2]+3 > optptr[1]) { 368 pp_ptr = optptr + 2; 369 goto error; 370 } 371 switch (optptr[3]&0xF) { 372 case IPOPT_TS_TSONLY: 373 if (skb) 374 timeptr = &optptr[optptr[2]-1]; 375 opt->ts_needtime = 1; 376 optptr[2] += 4; 377 break; 378 case IPOPT_TS_TSANDADDR: 379 if (optptr[2]+7 > optptr[1]) { 380 pp_ptr = optptr + 2; 381 goto error; 382 } 383 if (rt) { 384 spec_dst_fill(&spec_dst, skb); 385 memcpy(&optptr[optptr[2]-1], &spec_dst, 4); 386 timeptr = &optptr[optptr[2]+3]; 387 } 388 opt->ts_needaddr = 1; 389 opt->ts_needtime = 1; 390 optptr[2] += 8; 391 break; 392 case IPOPT_TS_PRESPEC: 393 if (optptr[2]+7 > optptr[1]) { 394 pp_ptr = optptr + 2; 395 goto error; 396 } 397 { 398 __be32 addr; 399 memcpy(&addr, &optptr[optptr[2]-1], 4); 400 if (inet_addr_type(net, addr) == RTN_UNICAST) 401 break; 402 if (skb) 403 timeptr = &optptr[optptr[2]+3]; 404 } 405 opt->ts_needtime = 1; 406 optptr[2] += 8; 407 break; 408 default: 409 if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) { 410 pp_ptr = optptr + 3; 411 goto error; 412 } 413 break; 414 } 415 if (timeptr) { 416 struct timespec tv; 417 u32 midtime; 418 getnstimeofday(&tv); 419 midtime = (tv.tv_sec % 86400) * MSEC_PER_SEC + tv.tv_nsec / NSEC_PER_MSEC; 420 put_unaligned_be32(midtime, timeptr); 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