1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * INET An implementation of the TCP/IP protocol suite for the LINUX 4 * operating system. INET is implemented using the BSD Socket 5 * interface as the means of communication with the user level. 6 * 7 * The options processing module for ip.c 8 * 9 * Authors: A.N.Kuznetsov 10 * 11 */ 12 13 #define pr_fmt(fmt) "IPv4: " fmt 14 15 #include <linux/capability.h> 16 #include <linux/module.h> 17 #include <linux/slab.h> 18 #include <linux/types.h> 19 #include <linux/uaccess.h> 20 #include <asm/unaligned.h> 21 #include <linux/skbuff.h> 22 #include <linux/ip.h> 23 #include <linux/icmp.h> 24 #include <linux/netdevice.h> 25 #include <linux/rtnetlink.h> 26 #include <net/sock.h> 27 #include <net/ip.h> 28 #include <net/icmp.h> 29 #include <net/route.h> 30 #include <net/cipso_ipv4.h> 31 #include <net/ip_fib.h> 32 33 /* 34 * Write options to IP header, record destination address to 35 * source route option, address of outgoing interface 36 * (we should already know it, so that this function is allowed be 37 * called only after routing decision) and timestamp, 38 * if we originate this datagram. 39 * 40 * daddr is real destination address, next hop is recorded in IP header. 41 * saddr is address of outgoing interface. 42 */ 43 44 void ip_options_build(struct sk_buff *skb, struct ip_options *opt, 45 __be32 daddr, struct rtable *rt) 46 { 47 unsigned char *iph = skb_network_header(skb); 48 49 memcpy(&(IPCB(skb)->opt), opt, sizeof(struct ip_options)); 50 memcpy(iph + sizeof(struct iphdr), opt->__data, opt->optlen); 51 opt = &(IPCB(skb)->opt); 52 53 if (opt->srr) 54 memcpy(iph + opt->srr + iph[opt->srr + 1] - 4, &daddr, 4); 55 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 } 67 68 /* 69 * Provided (sopt, skb) points to received options, 70 * build in dopt compiled option set appropriate for answering. 71 * i.e. invert SRR option, copy anothers, 72 * and grab room in RR/TS options. 73 * 74 * NOTE: dopt cannot point to skb. 75 */ 76 77 int __ip_options_echo(struct net *net, struct ip_options *dopt, 78 struct sk_buff *skb, const struct ip_options *sopt) 79 { 80 unsigned char *sptr, *dptr; 81 int soffset, doffset; 82 int optlen; 83 84 memset(dopt, 0, sizeof(struct ip_options)); 85 86 if (sopt->optlen == 0) 87 return 0; 88 89 sptr = skb_network_header(skb); 90 dptr = dopt->__data; 91 92 if (sopt->rr) { 93 optlen = sptr[sopt->rr+1]; 94 soffset = sptr[sopt->rr+2]; 95 dopt->rr = dopt->optlen + sizeof(struct iphdr); 96 memcpy(dptr, sptr+sopt->rr, optlen); 97 if (sopt->rr_needaddr && soffset <= optlen) { 98 if (soffset + 3 > optlen) 99 return -EINVAL; 100 dptr[2] = soffset + 4; 101 dopt->rr_needaddr = 1; 102 } 103 dptr += optlen; 104 dopt->optlen += optlen; 105 } 106 if (sopt->ts) { 107 optlen = sptr[sopt->ts+1]; 108 soffset = sptr[sopt->ts+2]; 109 dopt->ts = dopt->optlen + sizeof(struct iphdr); 110 memcpy(dptr, sptr+sopt->ts, optlen); 111 if (soffset <= optlen) { 112 if (sopt->ts_needaddr) { 113 if (soffset + 3 > optlen) 114 return -EINVAL; 115 dopt->ts_needaddr = 1; 116 soffset += 4; 117 } 118 if (sopt->ts_needtime) { 119 if (soffset + 3 > optlen) 120 return -EINVAL; 121 if ((dptr[3]&0xF) != IPOPT_TS_PRESPEC) { 122 dopt->ts_needtime = 1; 123 soffset += 4; 124 } else { 125 dopt->ts_needtime = 0; 126 127 if (soffset + 7 <= optlen) { 128 __be32 addr; 129 130 memcpy(&addr, dptr+soffset-1, 4); 131 if (inet_addr_type(net, addr) != RTN_UNICAST) { 132 dopt->ts_needtime = 1; 133 soffset += 8; 134 } 135 } 136 } 137 } 138 dptr[2] = soffset; 139 } 140 dptr += optlen; 141 dopt->optlen += optlen; 142 } 143 if (sopt->srr) { 144 unsigned char *start = sptr+sopt->srr; 145 __be32 faddr; 146 147 optlen = start[1]; 148 soffset = start[2]; 149 doffset = 0; 150 if (soffset > optlen) 151 soffset = optlen + 1; 152 soffset -= 4; 153 if (soffset > 3) { 154 memcpy(&faddr, &start[soffset-1], 4); 155 for (soffset -= 4, doffset = 4; soffset > 3; soffset -= 4, doffset += 4) 156 memcpy(&dptr[doffset-1], &start[soffset-1], 4); 157 /* 158 * RFC1812 requires to fix illegal source routes. 159 */ 160 if (memcmp(&ip_hdr(skb)->saddr, 161 &start[soffset + 3], 4) == 0) 162 doffset -= 4; 163 } 164 if (doffset > 3) { 165 dopt->faddr = faddr; 166 dptr[0] = start[0]; 167 dptr[1] = doffset+3; 168 dptr[2] = 4; 169 dptr += doffset+3; 170 dopt->srr = dopt->optlen + sizeof(struct iphdr); 171 dopt->optlen += doffset+3; 172 dopt->is_strictroute = sopt->is_strictroute; 173 } 174 } 175 if (sopt->cipso) { 176 optlen = sptr[sopt->cipso+1]; 177 dopt->cipso = dopt->optlen+sizeof(struct iphdr); 178 memcpy(dptr, sptr+sopt->cipso, optlen); 179 dptr += optlen; 180 dopt->optlen += optlen; 181 } 182 while (dopt->optlen & 3) { 183 *dptr++ = IPOPT_END; 184 dopt->optlen++; 185 } 186 return 0; 187 } 188 189 /* 190 * Options "fragmenting", just fill options not 191 * allowed in fragments with NOOPs. 192 * Simple and stupid 8), but the most efficient way. 193 */ 194 195 void ip_options_fragment(struct sk_buff *skb) 196 { 197 unsigned char *optptr = skb_network_header(skb) + sizeof(struct iphdr); 198 struct ip_options *opt = &(IPCB(skb)->opt); 199 int l = opt->optlen; 200 int optlen; 201 202 while (l > 0) { 203 switch (*optptr) { 204 case IPOPT_END: 205 return; 206 case IPOPT_NOOP: 207 l--; 208 optptr++; 209 continue; 210 } 211 optlen = optptr[1]; 212 if (optlen < 2 || optlen > l) 213 return; 214 if (!IPOPT_COPIED(*optptr)) 215 memset(optptr, IPOPT_NOOP, optlen); 216 l -= optlen; 217 optptr += optlen; 218 } 219 opt->ts = 0; 220 opt->rr = 0; 221 opt->rr_needaddr = 0; 222 opt->ts_needaddr = 0; 223 opt->ts_needtime = 0; 224 } 225 226 /* helper used by ip_options_compile() to call fib_compute_spec_dst() 227 * at most one time. 228 */ 229 static void spec_dst_fill(__be32 *spec_dst, struct sk_buff *skb) 230 { 231 if (*spec_dst == htonl(INADDR_ANY)) 232 *spec_dst = fib_compute_spec_dst(skb); 233 } 234 235 /* 236 * Verify options and fill pointers in struct options. 237 * Caller should clear *opt, and set opt->data. 238 * If opt == NULL, then skb->data should point to IP header. 239 */ 240 241 int __ip_options_compile(struct net *net, 242 struct ip_options *opt, struct sk_buff *skb, 243 __be32 *info) 244 { 245 __be32 spec_dst = htonl(INADDR_ANY); 246 unsigned char *pp_ptr = NULL; 247 struct rtable *rt = NULL; 248 unsigned char *optptr; 249 unsigned char *iph; 250 int optlen, l; 251 252 if (skb) { 253 rt = skb_rtable(skb); 254 optptr = (unsigned char *)&(ip_hdr(skb)[1]); 255 } else 256 optptr = opt->__data; 257 iph = optptr - sizeof(struct iphdr); 258 259 for (l = opt->optlen; l > 0; ) { 260 switch (*optptr) { 261 case IPOPT_END: 262 for (optptr++, l--; l > 0; optptr++, l--) { 263 if (*optptr != IPOPT_END) { 264 *optptr = IPOPT_END; 265 opt->is_changed = 1; 266 } 267 } 268 goto eol; 269 case IPOPT_NOOP: 270 l--; 271 optptr++; 272 continue; 273 } 274 if (unlikely(l < 2)) { 275 pp_ptr = optptr; 276 goto error; 277 } 278 optlen = optptr[1]; 279 if (optlen < 2 || optlen > l) { 280 pp_ptr = optptr; 281 goto error; 282 } 283 switch (*optptr) { 284 case IPOPT_SSRR: 285 case IPOPT_LSRR: 286 if (optlen < 3) { 287 pp_ptr = optptr + 1; 288 goto error; 289 } 290 if (optptr[2] < 4) { 291 pp_ptr = optptr + 2; 292 goto error; 293 } 294 /* NB: cf RFC-1812 5.2.4.1 */ 295 if (opt->srr) { 296 pp_ptr = optptr; 297 goto error; 298 } 299 if (!skb) { 300 if (optptr[2] != 4 || optlen < 7 || ((optlen-3) & 3)) { 301 pp_ptr = optptr + 1; 302 goto error; 303 } 304 memcpy(&opt->faddr, &optptr[3], 4); 305 if (optlen > 7) 306 memmove(&optptr[3], &optptr[7], optlen-7); 307 } 308 opt->is_strictroute = (optptr[0] == IPOPT_SSRR); 309 opt->srr = optptr - iph; 310 break; 311 case IPOPT_RR: 312 if (opt->rr) { 313 pp_ptr = optptr; 314 goto error; 315 } 316 if (optlen < 3) { 317 pp_ptr = optptr + 1; 318 goto error; 319 } 320 if (optptr[2] < 4) { 321 pp_ptr = optptr + 2; 322 goto error; 323 } 324 if (optptr[2] <= optlen) { 325 if (optptr[2]+3 > optlen) { 326 pp_ptr = optptr + 2; 327 goto error; 328 } 329 if (rt) { 330 spec_dst_fill(&spec_dst, skb); 331 memcpy(&optptr[optptr[2]-1], &spec_dst, 4); 332 opt->is_changed = 1; 333 } 334 optptr[2] += 4; 335 opt->rr_needaddr = 1; 336 } 337 opt->rr = optptr - iph; 338 break; 339 case IPOPT_TIMESTAMP: 340 if (opt->ts) { 341 pp_ptr = optptr; 342 goto error; 343 } 344 if (optlen < 4) { 345 pp_ptr = optptr + 1; 346 goto error; 347 } 348 if (optptr[2] < 5) { 349 pp_ptr = optptr + 2; 350 goto error; 351 } 352 if (optptr[2] <= optlen) { 353 unsigned char *timeptr = NULL; 354 if (optptr[2]+3 > optlen) { 355 pp_ptr = optptr + 2; 356 goto error; 357 } 358 switch (optptr[3]&0xF) { 359 case IPOPT_TS_TSONLY: 360 if (skb) 361 timeptr = &optptr[optptr[2]-1]; 362 opt->ts_needtime = 1; 363 optptr[2] += 4; 364 break; 365 case IPOPT_TS_TSANDADDR: 366 if (optptr[2]+7 > optlen) { 367 pp_ptr = optptr + 2; 368 goto error; 369 } 370 if (rt) { 371 spec_dst_fill(&spec_dst, skb); 372 memcpy(&optptr[optptr[2]-1], &spec_dst, 4); 373 timeptr = &optptr[optptr[2]+3]; 374 } 375 opt->ts_needaddr = 1; 376 opt->ts_needtime = 1; 377 optptr[2] += 8; 378 break; 379 case IPOPT_TS_PRESPEC: 380 if (optptr[2]+7 > optlen) { 381 pp_ptr = optptr + 2; 382 goto error; 383 } 384 { 385 __be32 addr; 386 memcpy(&addr, &optptr[optptr[2]-1], 4); 387 if (inet_addr_type(net, addr) == RTN_UNICAST) 388 break; 389 if (skb) 390 timeptr = &optptr[optptr[2]+3]; 391 } 392 opt->ts_needtime = 1; 393 optptr[2] += 8; 394 break; 395 default: 396 if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) { 397 pp_ptr = optptr + 3; 398 goto error; 399 } 400 break; 401 } 402 if (timeptr) { 403 __be32 midtime; 404 405 midtime = inet_current_timestamp(); 406 memcpy(timeptr, &midtime, 4); 407 opt->is_changed = 1; 408 } 409 } else if ((optptr[3]&0xF) != IPOPT_TS_PRESPEC) { 410 unsigned int overflow = optptr[3]>>4; 411 if (overflow == 15) { 412 pp_ptr = optptr + 3; 413 goto error; 414 } 415 if (skb) { 416 optptr[3] = (optptr[3]&0xF)|((overflow+1)<<4); 417 opt->is_changed = 1; 418 } 419 } 420 opt->ts = optptr - iph; 421 break; 422 case IPOPT_RA: 423 if (optlen < 4) { 424 pp_ptr = optptr + 1; 425 goto error; 426 } 427 if (optptr[2] == 0 && optptr[3] == 0) 428 opt->router_alert = optptr - iph; 429 break; 430 case IPOPT_CIPSO: 431 if ((!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) || opt->cipso) { 432 pp_ptr = optptr; 433 goto error; 434 } 435 opt->cipso = optptr - iph; 436 if (cipso_v4_validate(skb, &optptr)) { 437 pp_ptr = optptr; 438 goto error; 439 } 440 break; 441 case IPOPT_SEC: 442 case IPOPT_SID: 443 default: 444 if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) { 445 pp_ptr = optptr; 446 goto error; 447 } 448 break; 449 } 450 l -= optlen; 451 optptr += optlen; 452 } 453 454 eol: 455 if (!pp_ptr) 456 return 0; 457 458 error: 459 if (info) 460 *info = htonl((pp_ptr-iph)<<24); 461 return -EINVAL; 462 } 463 EXPORT_SYMBOL(__ip_options_compile); 464 465 int ip_options_compile(struct net *net, 466 struct ip_options *opt, struct sk_buff *skb) 467 { 468 int ret; 469 __be32 info; 470 471 ret = __ip_options_compile(net, opt, skb, &info); 472 if (ret != 0 && skb) 473 icmp_send(skb, ICMP_PARAMETERPROB, 0, info); 474 return ret; 475 } 476 EXPORT_SYMBOL(ip_options_compile); 477 478 /* 479 * Undo all the changes done by ip_options_compile(). 480 */ 481 482 void ip_options_undo(struct ip_options *opt) 483 { 484 if (opt->srr) { 485 unsigned char *optptr = opt->__data + opt->srr - sizeof(struct iphdr); 486 487 memmove(optptr + 7, optptr + 3, optptr[1] - 7); 488 memcpy(optptr + 3, &opt->faddr, 4); 489 } 490 if (opt->rr_needaddr) { 491 unsigned char *optptr = opt->__data + opt->rr - sizeof(struct iphdr); 492 493 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); 498 499 if (opt->ts_needtime) { 500 optptr[2] -= 4; 501 memset(&optptr[optptr[2] - 1], 0, 4); 502 if ((optptr[3] & 0xF) == IPOPT_TS_PRESPEC) 503 optptr[2] -= 4; 504 } 505 if (opt->ts_needaddr) { 506 optptr[2] -= 4; 507 memset(&optptr[optptr[2] - 1], 0, 4); 508 } 509 } 510 } 511 512 int ip_options_get(struct net *net, struct ip_options_rcu **optp, 513 sockptr_t data, int optlen) 514 { 515 struct ip_options_rcu *opt; 516 517 opt = kzalloc(sizeof(struct ip_options_rcu) + ((optlen + 3) & ~3), 518 GFP_KERNEL); 519 if (!opt) 520 return -ENOMEM; 521 if (optlen && copy_from_sockptr(opt->opt.__data, data, optlen)) { 522 kfree(opt); 523 return -EFAULT; 524 } 525 526 while (optlen & 3) 527 opt->opt.__data[optlen++] = IPOPT_END; 528 opt->opt.optlen = optlen; 529 if (optlen && ip_options_compile(net, &opt->opt, NULL)) { 530 kfree(opt); 531 return -EINVAL; 532 } 533 kfree(*optp); 534 *optp = opt; 535 return 0; 536 } 537 538 void ip_forward_options(struct sk_buff *skb) 539 { 540 struct ip_options *opt = &(IPCB(skb)->opt); 541 unsigned char *optptr; 542 struct rtable *rt = skb_rtable(skb); 543 unsigned char *raw = skb_network_header(skb); 544 545 if (opt->rr_needaddr) { 546 optptr = (unsigned char *)raw + opt->rr; 547 ip_rt_get_source(&optptr[optptr[2]-5], skb, rt); 548 opt->is_changed = 1; 549 } 550 if (opt->srr_is_hit) { 551 int srrptr, srrspace; 552 553 optptr = raw + opt->srr; 554 555 for ( srrptr = optptr[2], srrspace = optptr[1]; 556 srrptr <= srrspace; 557 srrptr += 4 558 ) { 559 if (srrptr + 3 > srrspace) 560 break; 561 if (memcmp(&opt->nexthop, &optptr[srrptr-1], 4) == 0) 562 break; 563 } 564 if (srrptr + 3 <= srrspace) { 565 opt->is_changed = 1; 566 ip_hdr(skb)->daddr = opt->nexthop; 567 ip_rt_get_source(&optptr[srrptr-1], skb, rt); 568 optptr[2] = srrptr+4; 569 } else { 570 net_crit_ratelimited("%s(): Argh! Destination lost!\n", 571 __func__); 572 } 573 if (opt->ts_needaddr) { 574 optptr = raw + opt->ts; 575 ip_rt_get_source(&optptr[optptr[2]-9], skb, rt); 576 opt->is_changed = 1; 577 } 578 } 579 if (opt->is_changed) { 580 opt->is_changed = 0; 581 ip_send_check(ip_hdr(skb)); 582 } 583 } 584 585 int ip_options_rcv_srr(struct sk_buff *skb, struct net_device *dev) 586 { 587 struct ip_options *opt = &(IPCB(skb)->opt); 588 int srrspace, srrptr; 589 __be32 nexthop; 590 struct iphdr *iph = ip_hdr(skb); 591 unsigned char *optptr = skb_network_header(skb) + opt->srr; 592 struct rtable *rt = skb_rtable(skb); 593 struct rtable *rt2; 594 unsigned long orefdst; 595 int err; 596 597 if (!rt) 598 return 0; 599 600 if (skb->pkt_type != PACKET_HOST) 601 return -EINVAL; 602 if (rt->rt_type == RTN_UNICAST) { 603 if (!opt->is_strictroute) 604 return 0; 605 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl(16<<24)); 606 return -EINVAL; 607 } 608 if (rt->rt_type != RTN_LOCAL) 609 return -EINVAL; 610 611 for (srrptr = optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4) { 612 if (srrptr + 3 > srrspace) { 613 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((opt->srr+2)<<24)); 614 return -EINVAL; 615 } 616 memcpy(&nexthop, &optptr[srrptr-1], 4); 617 618 orefdst = skb->_skb_refdst; 619 skb_dst_set(skb, NULL); 620 err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, dev); 621 rt2 = skb_rtable(skb); 622 if (err || (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) { 623 skb_dst_drop(skb); 624 skb->_skb_refdst = orefdst; 625 return -EINVAL; 626 } 627 refdst_drop(orefdst); 628 if (rt2->rt_type != RTN_LOCAL) 629 break; 630 /* Superfast 8) loopback forward */ 631 iph->daddr = nexthop; 632 opt->is_changed = 1; 633 } 634 if (srrptr <= srrspace) { 635 opt->srr_is_hit = 1; 636 opt->nexthop = nexthop; 637 opt->is_changed = 1; 638 } 639 return 0; 640 } 641 EXPORT_SYMBOL(ip_options_rcv_srr); 642