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 return; 242 } 243 244 /* 245 * Verify options and fill pointers in struct options. 246 * Caller should clear *opt, and set opt->data. 247 * If opt == NULL, then skb->data should point to IP header. 248 */ 249 250 int ip_options_compile(struct net *net, 251 struct ip_options * opt, struct sk_buff * skb) 252 { 253 int l; 254 unsigned char * iph; 255 unsigned char * optptr; 256 int optlen; 257 unsigned char * pp_ptr = NULL; 258 struct rtable *rt = NULL; 259 260 if (skb != NULL) { 261 rt = skb_rtable(skb); 262 optptr = (unsigned char *)&(ip_hdr(skb)[1]); 263 } else 264 optptr = opt->__data; 265 iph = optptr - sizeof(struct iphdr); 266 267 for (l = opt->optlen; l > 0; ) { 268 switch (*optptr) { 269 case IPOPT_END: 270 for (optptr++, l--; l>0; optptr++, l--) { 271 if (*optptr != IPOPT_END) { 272 *optptr = IPOPT_END; 273 opt->is_changed = 1; 274 } 275 } 276 goto eol; 277 case IPOPT_NOOP: 278 l--; 279 optptr++; 280 continue; 281 } 282 optlen = optptr[1]; 283 if (optlen<2 || optlen>l) { 284 pp_ptr = optptr; 285 goto error; 286 } 287 switch (*optptr) { 288 case IPOPT_SSRR: 289 case IPOPT_LSRR: 290 if (optlen < 3) { 291 pp_ptr = optptr + 1; 292 goto error; 293 } 294 if (optptr[2] < 4) { 295 pp_ptr = optptr + 2; 296 goto error; 297 } 298 /* NB: cf RFC-1812 5.2.4.1 */ 299 if (opt->srr) { 300 pp_ptr = optptr; 301 goto error; 302 } 303 if (!skb) { 304 if (optptr[2] != 4 || optlen < 7 || ((optlen-3) & 3)) { 305 pp_ptr = optptr + 1; 306 goto error; 307 } 308 memcpy(&opt->faddr, &optptr[3], 4); 309 if (optlen > 7) 310 memmove(&optptr[3], &optptr[7], optlen-7); 311 } 312 opt->is_strictroute = (optptr[0] == IPOPT_SSRR); 313 opt->srr = optptr - iph; 314 break; 315 case IPOPT_RR: 316 if (opt->rr) { 317 pp_ptr = optptr; 318 goto error; 319 } 320 if (optlen < 3) { 321 pp_ptr = optptr + 1; 322 goto error; 323 } 324 if (optptr[2] < 4) { 325 pp_ptr = optptr + 2; 326 goto error; 327 } 328 if (optptr[2] <= optlen) { 329 if (optptr[2]+3 > optlen) { 330 pp_ptr = optptr + 2; 331 goto error; 332 } 333 if (skb) { 334 memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4); 335 opt->is_changed = 1; 336 } 337 optptr[2] += 4; 338 opt->rr_needaddr = 1; 339 } 340 opt->rr = optptr - iph; 341 break; 342 case IPOPT_TIMESTAMP: 343 if (opt->ts) { 344 pp_ptr = optptr; 345 goto error; 346 } 347 if (optlen < 4) { 348 pp_ptr = optptr + 1; 349 goto error; 350 } 351 if (optptr[2] < 5) { 352 pp_ptr = optptr + 2; 353 goto error; 354 } 355 if (optptr[2] <= optlen) { 356 __be32 *timeptr = NULL; 357 if (optptr[2]+3 > optptr[1]) { 358 pp_ptr = optptr + 2; 359 goto error; 360 } 361 switch (optptr[3]&0xF) { 362 case IPOPT_TS_TSONLY: 363 opt->ts = optptr - iph; 364 if (skb) 365 timeptr = (__be32*)&optptr[optptr[2]-1]; 366 opt->ts_needtime = 1; 367 optptr[2] += 4; 368 break; 369 case IPOPT_TS_TSANDADDR: 370 if (optptr[2]+7 > optptr[1]) { 371 pp_ptr = optptr + 2; 372 goto error; 373 } 374 opt->ts = optptr - iph; 375 if (skb) { 376 memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4); 377 timeptr = (__be32*)&optptr[optptr[2]+3]; 378 } 379 opt->ts_needaddr = 1; 380 opt->ts_needtime = 1; 381 optptr[2] += 8; 382 break; 383 case IPOPT_TS_PRESPEC: 384 if (optptr[2]+7 > optptr[1]) { 385 pp_ptr = optptr + 2; 386 goto error; 387 } 388 opt->ts = optptr - iph; 389 { 390 __be32 addr; 391 memcpy(&addr, &optptr[optptr[2]-1], 4); 392 if (inet_addr_type(net, addr) == RTN_UNICAST) 393 break; 394 if (skb) 395 timeptr = (__be32*)&optptr[optptr[2]+3]; 396 } 397 opt->ts_needtime = 1; 398 optptr[2] += 8; 399 break; 400 default: 401 if (!skb && !capable(CAP_NET_RAW)) { 402 pp_ptr = optptr + 3; 403 goto error; 404 } 405 break; 406 } 407 if (timeptr) { 408 struct timespec tv; 409 __be32 midtime; 410 getnstimeofday(&tv); 411 midtime = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + tv.tv_nsec / NSEC_PER_MSEC); 412 memcpy(timeptr, &midtime, sizeof(__be32)); 413 opt->is_changed = 1; 414 } 415 } else { 416 unsigned overflow = optptr[3]>>4; 417 if (overflow == 15) { 418 pp_ptr = optptr + 3; 419 goto error; 420 } 421 opt->ts = optptr - iph; 422 if (skb) { 423 optptr[3] = (optptr[3]&0xF)|((overflow+1)<<4); 424 opt->is_changed = 1; 425 } 426 } 427 break; 428 case IPOPT_RA: 429 if (optlen < 4) { 430 pp_ptr = optptr + 1; 431 goto error; 432 } 433 if (optptr[2] == 0 && optptr[3] == 0) 434 opt->router_alert = optptr - iph; 435 break; 436 case IPOPT_CIPSO: 437 if ((!skb && !capable(CAP_NET_RAW)) || opt->cipso) { 438 pp_ptr = optptr; 439 goto error; 440 } 441 opt->cipso = optptr - iph; 442 if (cipso_v4_validate(skb, &optptr)) { 443 pp_ptr = optptr; 444 goto error; 445 } 446 break; 447 case IPOPT_SEC: 448 case IPOPT_SID: 449 default: 450 if (!skb && !capable(CAP_NET_RAW)) { 451 pp_ptr = optptr; 452 goto error; 453 } 454 break; 455 } 456 l -= optlen; 457 optptr += optlen; 458 } 459 460 eol: 461 if (!pp_ptr) 462 return 0; 463 464 error: 465 if (skb) { 466 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((pp_ptr-iph)<<24)); 467 } 468 return -EINVAL; 469 } 470 471 472 /* 473 * Undo all the changes done by ip_options_compile(). 474 */ 475 476 void ip_options_undo(struct ip_options * opt) 477 { 478 if (opt->srr) { 479 unsigned char * optptr = opt->__data+opt->srr-sizeof(struct iphdr); 480 memmove(optptr+7, optptr+3, optptr[1]-7); 481 memcpy(optptr+3, &opt->faddr, 4); 482 } 483 if (opt->rr_needaddr) { 484 unsigned char * optptr = opt->__data+opt->rr-sizeof(struct iphdr); 485 optptr[2] -= 4; 486 memset(&optptr[optptr[2]-1], 0, 4); 487 } 488 if (opt->ts) { 489 unsigned char * optptr = opt->__data+opt->ts-sizeof(struct iphdr); 490 if (opt->ts_needtime) { 491 optptr[2] -= 4; 492 memset(&optptr[optptr[2]-1], 0, 4); 493 if ((optptr[3]&0xF) == IPOPT_TS_PRESPEC) 494 optptr[2] -= 4; 495 } 496 if (opt->ts_needaddr) { 497 optptr[2] -= 4; 498 memset(&optptr[optptr[2]-1], 0, 4); 499 } 500 } 501 } 502 503 static struct ip_options *ip_options_get_alloc(const int optlen) 504 { 505 return kzalloc(sizeof(struct ip_options) + ((optlen + 3) & ~3), 506 GFP_KERNEL); 507 } 508 509 static int ip_options_get_finish(struct net *net, struct ip_options **optp, 510 struct ip_options *opt, int optlen) 511 { 512 while (optlen & 3) 513 opt->__data[optlen++] = IPOPT_END; 514 opt->optlen = optlen; 515 if (optlen && ip_options_compile(net, opt, NULL)) { 516 kfree(opt); 517 return -EINVAL; 518 } 519 kfree(*optp); 520 *optp = opt; 521 return 0; 522 } 523 524 int ip_options_get_from_user(struct net *net, struct ip_options **optp, 525 unsigned char __user *data, int optlen) 526 { 527 struct ip_options *opt = ip_options_get_alloc(optlen); 528 529 if (!opt) 530 return -ENOMEM; 531 if (optlen && copy_from_user(opt->__data, data, optlen)) { 532 kfree(opt); 533 return -EFAULT; 534 } 535 return ip_options_get_finish(net, optp, opt, optlen); 536 } 537 538 int ip_options_get(struct net *net, struct ip_options **optp, 539 unsigned char *data, int optlen) 540 { 541 struct ip_options *opt = ip_options_get_alloc(optlen); 542 543 if (!opt) 544 return -ENOMEM; 545 if (optlen) 546 memcpy(opt->__data, data, optlen); 547 return ip_options_get_finish(net, optp, opt, optlen); 548 } 549 550 void ip_forward_options(struct sk_buff *skb) 551 { 552 struct ip_options * opt = &(IPCB(skb)->opt); 553 unsigned char * optptr; 554 struct rtable *rt = skb_rtable(skb); 555 unsigned char *raw = skb_network_header(skb); 556 557 if (opt->rr_needaddr) { 558 optptr = (unsigned char *)raw + opt->rr; 559 ip_rt_get_source(&optptr[optptr[2]-5], rt); 560 opt->is_changed = 1; 561 } 562 if (opt->srr_is_hit) { 563 int srrptr, srrspace; 564 565 optptr = raw + opt->srr; 566 567 for ( srrptr=optptr[2], srrspace = optptr[1]; 568 srrptr <= srrspace; 569 srrptr += 4 570 ) { 571 if (srrptr + 3 > srrspace) 572 break; 573 if (memcmp(&rt->rt_dst, &optptr[srrptr-1], 4) == 0) 574 break; 575 } 576 if (srrptr + 3 <= srrspace) { 577 opt->is_changed = 1; 578 ip_rt_get_source(&optptr[srrptr-1], rt); 579 ip_hdr(skb)->daddr = rt->rt_dst; 580 optptr[2] = srrptr+4; 581 } else if (net_ratelimit()) 582 printk(KERN_CRIT "ip_forward(): Argh! Destination lost!\n"); 583 if (opt->ts_needaddr) { 584 optptr = raw + opt->ts; 585 ip_rt_get_source(&optptr[optptr[2]-9], rt); 586 opt->is_changed = 1; 587 } 588 } 589 if (opt->is_changed) { 590 opt->is_changed = 0; 591 ip_send_check(ip_hdr(skb)); 592 } 593 } 594 595 int ip_options_rcv_srr(struct sk_buff *skb) 596 { 597 struct ip_options *opt = &(IPCB(skb)->opt); 598 int srrspace, srrptr; 599 __be32 nexthop; 600 struct iphdr *iph = ip_hdr(skb); 601 unsigned char *optptr = skb_network_header(skb) + opt->srr; 602 struct rtable *rt = skb_rtable(skb); 603 struct rtable *rt2; 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 rt = skb_rtable(skb); 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 ip_rt_put(rt2); 633 skb_dst_set(skb, &rt->u.dst); 634 return -EINVAL; 635 } 636 ip_rt_put(rt); 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