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 * Version: $Id: ip_options.c,v 1.21 2001/09/01 00:31:50 davem Exp $ 9 * 10 * Authors: A.N.Kuznetsov 11 * 12 */ 13 14 #include <linux/capability.h> 15 #include <linux/module.h> 16 #include <linux/types.h> 17 #include <asm/uaccess.h> 18 #include <linux/skbuff.h> 19 #include <linux/ip.h> 20 #include <linux/icmp.h> 21 #include <linux/netdevice.h> 22 #include <linux/rtnetlink.h> 23 #include <net/sock.h> 24 #include <net/ip.h> 25 #include <net/icmp.h> 26 #include <net/route.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 u32 daddr, struct rtable *rt, int is_frag) 41 { 42 unsigned char * iph = skb->nh.raw; 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 opt->is_data = 0; 48 49 if (opt->srr) 50 memcpy(iph+opt->srr+iph[opt->srr+1]-4, &daddr, 4); 51 52 if (!is_frag) { 53 if (opt->rr_needaddr) 54 ip_rt_get_source(iph+opt->rr+iph[opt->rr+2]-5, rt); 55 if (opt->ts_needaddr) 56 ip_rt_get_source(iph+opt->ts+iph[opt->ts+2]-9, rt); 57 if (opt->ts_needtime) { 58 struct timeval tv; 59 __u32 midtime; 60 do_gettimeofday(&tv); 61 midtime = htonl((tv.tv_sec % 86400) * 1000 + tv.tv_usec / 1000); 62 memcpy(iph+opt->ts+iph[opt->ts+2]-5, &midtime, 4); 63 } 64 return; 65 } 66 if (opt->rr) { 67 memset(iph+opt->rr, IPOPT_NOP, iph[opt->rr+1]); 68 opt->rr = 0; 69 opt->rr_needaddr = 0; 70 } 71 if (opt->ts) { 72 memset(iph+opt->ts, IPOPT_NOP, iph[opt->ts+1]); 73 opt->ts = 0; 74 opt->ts_needaddr = opt->ts_needtime = 0; 75 } 76 } 77 78 /* 79 * Provided (sopt, skb) points to received options, 80 * build in dopt compiled option set appropriate for answering. 81 * i.e. invert SRR option, copy anothers, 82 * and grab room in RR/TS options. 83 * 84 * NOTE: dopt cannot point to skb. 85 */ 86 87 int ip_options_echo(struct ip_options * dopt, struct sk_buff * skb) 88 { 89 struct ip_options *sopt; 90 unsigned char *sptr, *dptr; 91 int soffset, doffset; 92 int optlen; 93 u32 daddr; 94 95 memset(dopt, 0, sizeof(struct ip_options)); 96 97 dopt->is_data = 1; 98 99 sopt = &(IPCB(skb)->opt); 100 101 if (sopt->optlen == 0) { 102 dopt->optlen = 0; 103 return 0; 104 } 105 106 sptr = skb->nh.raw; 107 dptr = dopt->__data; 108 109 if (skb->dst) 110 daddr = ((struct rtable*)skb->dst)->rt_spec_dst; 111 else 112 daddr = skb->nh.iph->daddr; 113 114 if (sopt->rr) { 115 optlen = sptr[sopt->rr+1]; 116 soffset = sptr[sopt->rr+2]; 117 dopt->rr = dopt->optlen + sizeof(struct iphdr); 118 memcpy(dptr, sptr+sopt->rr, optlen); 119 if (sopt->rr_needaddr && soffset <= optlen) { 120 if (soffset + 3 > optlen) 121 return -EINVAL; 122 dptr[2] = soffset + 4; 123 dopt->rr_needaddr = 1; 124 } 125 dptr += optlen; 126 dopt->optlen += optlen; 127 } 128 if (sopt->ts) { 129 optlen = sptr[sopt->ts+1]; 130 soffset = sptr[sopt->ts+2]; 131 dopt->ts = dopt->optlen + sizeof(struct iphdr); 132 memcpy(dptr, sptr+sopt->ts, optlen); 133 if (soffset <= optlen) { 134 if (sopt->ts_needaddr) { 135 if (soffset + 3 > optlen) 136 return -EINVAL; 137 dopt->ts_needaddr = 1; 138 soffset += 4; 139 } 140 if (sopt->ts_needtime) { 141 if (soffset + 3 > optlen) 142 return -EINVAL; 143 if ((dptr[3]&0xF) != IPOPT_TS_PRESPEC) { 144 dopt->ts_needtime = 1; 145 soffset += 4; 146 } else { 147 dopt->ts_needtime = 0; 148 149 if (soffset + 8 <= optlen) { 150 __u32 addr; 151 152 memcpy(&addr, sptr+soffset-1, 4); 153 if (inet_addr_type(addr) != RTN_LOCAL) { 154 dopt->ts_needtime = 1; 155 soffset += 8; 156 } 157 } 158 } 159 } 160 dptr[2] = soffset; 161 } 162 dptr += optlen; 163 dopt->optlen += optlen; 164 } 165 if (sopt->srr) { 166 unsigned char * start = sptr+sopt->srr; 167 u32 faddr; 168 169 optlen = start[1]; 170 soffset = start[2]; 171 doffset = 0; 172 if (soffset > optlen) 173 soffset = optlen + 1; 174 soffset -= 4; 175 if (soffset > 3) { 176 memcpy(&faddr, &start[soffset-1], 4); 177 for (soffset-=4, doffset=4; soffset > 3; soffset-=4, doffset+=4) 178 memcpy(&dptr[doffset-1], &start[soffset-1], 4); 179 /* 180 * RFC1812 requires to fix illegal source routes. 181 */ 182 if (memcmp(&skb->nh.iph->saddr, &start[soffset+3], 4) == 0) 183 doffset -= 4; 184 } 185 if (doffset > 3) { 186 memcpy(&start[doffset-1], &daddr, 4); 187 dopt->faddr = faddr; 188 dptr[0] = start[0]; 189 dptr[1] = doffset+3; 190 dptr[2] = 4; 191 dptr += doffset+3; 192 dopt->srr = dopt->optlen + sizeof(struct iphdr); 193 dopt->optlen += doffset+3; 194 dopt->is_strictroute = sopt->is_strictroute; 195 } 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->nh.raw + 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 return; 240 } 241 242 /* 243 * Verify options and fill pointers in struct options. 244 * Caller should clear *opt, and set opt->data. 245 * If opt == NULL, then skb->data should point to IP header. 246 */ 247 248 int ip_options_compile(struct ip_options * opt, struct sk_buff * skb) 249 { 250 int l; 251 unsigned char * iph; 252 unsigned char * optptr; 253 int optlen; 254 unsigned char * pp_ptr = NULL; 255 struct rtable *rt = skb ? (struct rtable*)skb->dst : NULL; 256 257 if (!opt) { 258 opt = &(IPCB(skb)->opt); 259 memset(opt, 0, sizeof(struct ip_options)); 260 iph = skb->nh.raw; 261 opt->optlen = ((struct iphdr *)iph)->ihl*4 - sizeof(struct iphdr); 262 optptr = iph + sizeof(struct iphdr); 263 opt->is_data = 0; 264 } else { 265 optptr = opt->is_data ? opt->__data : (unsigned char*)&(skb->nh.iph[1]); 266 iph = optptr - sizeof(struct iphdr); 267 } 268 269 for (l = opt->optlen; l > 0; ) { 270 switch (*optptr) { 271 case IPOPT_END: 272 for (optptr++, l--; l>0; optptr++, l--) { 273 if (*optptr != IPOPT_END) { 274 *optptr = IPOPT_END; 275 opt->is_changed = 1; 276 } 277 } 278 goto eol; 279 case IPOPT_NOOP: 280 l--; 281 optptr++; 282 continue; 283 } 284 optlen = optptr[1]; 285 if (optlen<2 || optlen>l) { 286 pp_ptr = optptr; 287 goto error; 288 } 289 switch (*optptr) { 290 case IPOPT_SSRR: 291 case IPOPT_LSRR: 292 if (optlen < 3) { 293 pp_ptr = optptr + 1; 294 goto error; 295 } 296 if (optptr[2] < 4) { 297 pp_ptr = optptr + 2; 298 goto error; 299 } 300 /* NB: cf RFC-1812 5.2.4.1 */ 301 if (opt->srr) { 302 pp_ptr = optptr; 303 goto error; 304 } 305 if (!skb) { 306 if (optptr[2] != 4 || optlen < 7 || ((optlen-3) & 3)) { 307 pp_ptr = optptr + 1; 308 goto error; 309 } 310 memcpy(&opt->faddr, &optptr[3], 4); 311 if (optlen > 7) 312 memmove(&optptr[3], &optptr[7], optlen-7); 313 } 314 opt->is_strictroute = (optptr[0] == IPOPT_SSRR); 315 opt->srr = optptr - iph; 316 break; 317 case IPOPT_RR: 318 if (opt->rr) { 319 pp_ptr = optptr; 320 goto error; 321 } 322 if (optlen < 3) { 323 pp_ptr = optptr + 1; 324 goto error; 325 } 326 if (optptr[2] < 4) { 327 pp_ptr = optptr + 2; 328 goto error; 329 } 330 if (optptr[2] <= optlen) { 331 if (optptr[2]+3 > optlen) { 332 pp_ptr = optptr + 2; 333 goto error; 334 } 335 if (skb) { 336 memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4); 337 opt->is_changed = 1; 338 } 339 optptr[2] += 4; 340 opt->rr_needaddr = 1; 341 } 342 opt->rr = optptr - iph; 343 break; 344 case IPOPT_TIMESTAMP: 345 if (opt->ts) { 346 pp_ptr = optptr; 347 goto error; 348 } 349 if (optlen < 4) { 350 pp_ptr = optptr + 1; 351 goto error; 352 } 353 if (optptr[2] < 5) { 354 pp_ptr = optptr + 2; 355 goto error; 356 } 357 if (optptr[2] <= optlen) { 358 __u32 * timeptr = NULL; 359 if (optptr[2]+3 > optptr[1]) { 360 pp_ptr = optptr + 2; 361 goto error; 362 } 363 switch (optptr[3]&0xF) { 364 case IPOPT_TS_TSONLY: 365 opt->ts = optptr - iph; 366 if (skb) 367 timeptr = (__u32*)&optptr[optptr[2]-1]; 368 opt->ts_needtime = 1; 369 optptr[2] += 4; 370 break; 371 case IPOPT_TS_TSANDADDR: 372 if (optptr[2]+7 > optptr[1]) { 373 pp_ptr = optptr + 2; 374 goto error; 375 } 376 opt->ts = optptr - iph; 377 if (skb) { 378 memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4); 379 timeptr = (__u32*)&optptr[optptr[2]+3]; 380 } 381 opt->ts_needaddr = 1; 382 opt->ts_needtime = 1; 383 optptr[2] += 8; 384 break; 385 case IPOPT_TS_PRESPEC: 386 if (optptr[2]+7 > optptr[1]) { 387 pp_ptr = optptr + 2; 388 goto error; 389 } 390 opt->ts = optptr - iph; 391 { 392 u32 addr; 393 memcpy(&addr, &optptr[optptr[2]-1], 4); 394 if (inet_addr_type(addr) == RTN_UNICAST) 395 break; 396 if (skb) 397 timeptr = (__u32*)&optptr[optptr[2]+3]; 398 } 399 opt->ts_needtime = 1; 400 optptr[2] += 8; 401 break; 402 default: 403 if (!skb && !capable(CAP_NET_RAW)) { 404 pp_ptr = optptr + 3; 405 goto error; 406 } 407 break; 408 } 409 if (timeptr) { 410 struct timeval tv; 411 __u32 midtime; 412 do_gettimeofday(&tv); 413 midtime = htonl((tv.tv_sec % 86400) * 1000 + tv.tv_usec / 1000); 414 memcpy(timeptr, &midtime, sizeof(__u32)); 415 opt->is_changed = 1; 416 } 417 } else { 418 unsigned overflow = optptr[3]>>4; 419 if (overflow == 15) { 420 pp_ptr = optptr + 3; 421 goto error; 422 } 423 opt->ts = optptr - iph; 424 if (skb) { 425 optptr[3] = (optptr[3]&0xF)|((overflow+1)<<4); 426 opt->is_changed = 1; 427 } 428 } 429 break; 430 case IPOPT_RA: 431 if (optlen < 4) { 432 pp_ptr = optptr + 1; 433 goto error; 434 } 435 if (optptr[2] == 0 && optptr[3] == 0) 436 opt->router_alert = optptr - iph; 437 break; 438 case IPOPT_SEC: 439 case IPOPT_SID: 440 default: 441 if (!skb && !capable(CAP_NET_RAW)) { 442 pp_ptr = optptr; 443 goto error; 444 } 445 break; 446 } 447 l -= optlen; 448 optptr += optlen; 449 } 450 451 eol: 452 if (!pp_ptr) 453 return 0; 454 455 error: 456 if (skb) { 457 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((pp_ptr-iph)<<24)); 458 } 459 return -EINVAL; 460 } 461 462 463 /* 464 * Undo all the changes done by ip_options_compile(). 465 */ 466 467 void ip_options_undo(struct ip_options * opt) 468 { 469 if (opt->srr) { 470 unsigned char * optptr = opt->__data+opt->srr-sizeof(struct iphdr); 471 memmove(optptr+7, optptr+3, optptr[1]-7); 472 memcpy(optptr+3, &opt->faddr, 4); 473 } 474 if (opt->rr_needaddr) { 475 unsigned char * optptr = opt->__data+opt->rr-sizeof(struct iphdr); 476 optptr[2] -= 4; 477 memset(&optptr[optptr[2]-1], 0, 4); 478 } 479 if (opt->ts) { 480 unsigned char * optptr = opt->__data+opt->ts-sizeof(struct iphdr); 481 if (opt->ts_needtime) { 482 optptr[2] -= 4; 483 memset(&optptr[optptr[2]-1], 0, 4); 484 if ((optptr[3]&0xF) == IPOPT_TS_PRESPEC) 485 optptr[2] -= 4; 486 } 487 if (opt->ts_needaddr) { 488 optptr[2] -= 4; 489 memset(&optptr[optptr[2]-1], 0, 4); 490 } 491 } 492 } 493 494 static struct ip_options *ip_options_get_alloc(const int optlen) 495 { 496 struct ip_options *opt = kmalloc(sizeof(*opt) + ((optlen + 3) & ~3), 497 GFP_KERNEL); 498 if (opt) 499 memset(opt, 0, sizeof(*opt)); 500 return opt; 501 } 502 503 static int ip_options_get_finish(struct ip_options **optp, 504 struct ip_options *opt, int optlen) 505 { 506 while (optlen & 3) 507 opt->__data[optlen++] = IPOPT_END; 508 opt->optlen = optlen; 509 opt->is_data = 1; 510 opt->is_setbyuser = 1; 511 if (optlen && ip_options_compile(opt, NULL)) { 512 kfree(opt); 513 return -EINVAL; 514 } 515 kfree(*optp); 516 *optp = opt; 517 return 0; 518 } 519 520 int ip_options_get_from_user(struct ip_options **optp, unsigned char __user *data, int optlen) 521 { 522 struct ip_options *opt = ip_options_get_alloc(optlen); 523 524 if (!opt) 525 return -ENOMEM; 526 if (optlen && copy_from_user(opt->__data, data, optlen)) { 527 kfree(opt); 528 return -EFAULT; 529 } 530 return ip_options_get_finish(optp, opt, optlen); 531 } 532 533 int ip_options_get(struct ip_options **optp, unsigned char *data, int optlen) 534 { 535 struct ip_options *opt = ip_options_get_alloc(optlen); 536 537 if (!opt) 538 return -ENOMEM; 539 if (optlen) 540 memcpy(opt->__data, data, optlen); 541 return ip_options_get_finish(optp, opt, optlen); 542 } 543 544 void ip_forward_options(struct sk_buff *skb) 545 { 546 struct ip_options * opt = &(IPCB(skb)->opt); 547 unsigned char * optptr; 548 struct rtable *rt = (struct rtable*)skb->dst; 549 unsigned char *raw = skb->nh.raw; 550 551 if (opt->rr_needaddr) { 552 optptr = (unsigned char *)raw + opt->rr; 553 ip_rt_get_source(&optptr[optptr[2]-5], rt); 554 opt->is_changed = 1; 555 } 556 if (opt->srr_is_hit) { 557 int srrptr, srrspace; 558 559 optptr = raw + opt->srr; 560 561 for ( srrptr=optptr[2], srrspace = optptr[1]; 562 srrptr <= srrspace; 563 srrptr += 4 564 ) { 565 if (srrptr + 3 > srrspace) 566 break; 567 if (memcmp(&rt->rt_dst, &optptr[srrptr-1], 4) == 0) 568 break; 569 } 570 if (srrptr + 3 <= srrspace) { 571 opt->is_changed = 1; 572 ip_rt_get_source(&optptr[srrptr-1], rt); 573 skb->nh.iph->daddr = rt->rt_dst; 574 optptr[2] = srrptr+4; 575 } else if (net_ratelimit()) 576 printk(KERN_CRIT "ip_forward(): Argh! Destination lost!\n"); 577 if (opt->ts_needaddr) { 578 optptr = raw + opt->ts; 579 ip_rt_get_source(&optptr[optptr[2]-9], rt); 580 opt->is_changed = 1; 581 } 582 } 583 if (opt->is_changed) { 584 opt->is_changed = 0; 585 ip_send_check(skb->nh.iph); 586 } 587 } 588 589 int ip_options_rcv_srr(struct sk_buff *skb) 590 { 591 struct ip_options *opt = &(IPCB(skb)->opt); 592 int srrspace, srrptr; 593 u32 nexthop; 594 struct iphdr *iph = skb->nh.iph; 595 unsigned char * optptr = skb->nh.raw + opt->srr; 596 struct rtable *rt = (struct rtable*)skb->dst; 597 struct rtable *rt2; 598 int err; 599 600 if (!opt->srr) 601 return 0; 602 603 if (skb->pkt_type != PACKET_HOST) 604 return -EINVAL; 605 if (rt->rt_type == RTN_UNICAST) { 606 if (!opt->is_strictroute) 607 return 0; 608 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl(16<<24)); 609 return -EINVAL; 610 } 611 if (rt->rt_type != RTN_LOCAL) 612 return -EINVAL; 613 614 for (srrptr=optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4) { 615 if (srrptr + 3 > srrspace) { 616 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((opt->srr+2)<<24)); 617 return -EINVAL; 618 } 619 memcpy(&nexthop, &optptr[srrptr-1], 4); 620 621 rt = (struct rtable*)skb->dst; 622 skb->dst = NULL; 623 err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, skb->dev); 624 rt2 = (struct rtable*)skb->dst; 625 if (err || (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) { 626 ip_rt_put(rt2); 627 skb->dst = &rt->u.dst; 628 return -EINVAL; 629 } 630 ip_rt_put(rt); 631 if (rt2->rt_type != RTN_LOCAL) 632 break; 633 /* Superfast 8) loopback forward */ 634 memcpy(&iph->daddr, &optptr[srrptr-1], 4); 635 opt->is_changed = 1; 636 } 637 if (srrptr <= srrspace) { 638 opt->srr_is_hit = 1; 639 opt->is_changed = 1; 640 } 641 return 0; 642 } 643