1 /* $FreeBSD: src/sys/contrib/pf/net/pf_norm.c,v 1.10 2004/08/14 15:32:40 dwmalone Exp $ */ 2 /* $OpenBSD: pf_norm.c,v 1.80.2.1 2004/04/30 21:46:33 brad Exp $ */ 3 /* add $OpenBSD: pf_norm.c,v 1.87 2004/05/11 07:34:11 dhartmei Exp $ */ 4 /* $DragonFly: src/sys/net/pf/pf_norm.c,v 1.9 2007/08/11 18:53:31 dillon Exp $ */ 5 6 /* 7 * Copyright (c) 2004 The DragonFly Project. All rights reserved. 8 * 9 * Copyright 2001 Niels Provos <provos@citi.umich.edu> 10 * All rights reserved. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 #include "opt_inet.h" 34 #include "opt_inet6.h" 35 36 #include <sys/param.h> 37 #include <sys/systm.h> 38 #include <sys/mbuf.h> 39 #include <sys/filio.h> 40 #include <sys/fcntl.h> 41 #include <sys/socket.h> 42 #include <sys/kernel.h> 43 #include <sys/time.h> 44 #include <vm/vm_zone.h> 45 46 #include <net/if.h> 47 #include <net/if_types.h> 48 #include <net/bpf.h> 49 #include <net/route.h> 50 #include <net/pf/if_pflog.h> 51 52 #include <netinet/in.h> 53 #include <netinet/in_var.h> 54 #include <netinet/in_systm.h> 55 #include <netinet/ip.h> 56 #include <netinet/ip_var.h> 57 #include <netinet/tcp.h> 58 #include <netinet/tcp_seq.h> 59 #include <netinet/udp.h> 60 #include <netinet/ip_icmp.h> 61 62 #ifdef INET6 63 #include <netinet/ip6.h> 64 #endif /* INET6 */ 65 66 #include <net/pf/pfvar.h> 67 68 #ifdef INET6 69 /* 70 * XXX: This should go to netinet/ip6.h (KAME) 71 */ 72 /* IPv6 options: common part */ 73 struct ip6_opt { 74 u_int8_t ip6o_type; 75 u_int8_t ip6o_len; 76 } __packed; 77 78 /* Jumbo Payload Option */ 79 struct ip6_opt_jumbo { 80 u_int8_t ip6oj_type; 81 u_int8_t ip6oj_len; 82 u_int8_t ip6oj_jumbo_len[4]; 83 } __packed; 84 85 /* NSAP Address Option */ 86 struct ip6_opt_nsap { 87 u_int8_t ip6on_type; 88 u_int8_t ip6on_len; 89 u_int8_t ip6on_src_nsap_len; 90 u_int8_t ip6on_dst_nsap_len; 91 /* followed by source NSAP */ 92 /* followed by destination NSAP */ 93 } __packed; 94 95 /* Tunnel Limit Option */ 96 struct ip6_opt_tunnel { 97 u_int8_t ip6ot_type; 98 u_int8_t ip6ot_len; 99 u_int8_t ip6ot_encap_limit; 100 } __packed; 101 102 /* Router Alert Option */ 103 struct ip6_opt_router { 104 u_int8_t ip6or_type; 105 u_int8_t ip6or_len; 106 u_int8_t ip6or_value[2]; 107 } __packed; 108 #endif /* INET6 */ 109 110 #define PFFRAG_SEENLAST 0x0001 /* Seen the last fragment for this */ 111 #define PFFRAG_NOBUFFER 0x0002 /* Non-buffering fragment cache */ 112 #define PFFRAG_DROP 0x0004 /* Drop all fragments */ 113 #define BUFFER_FRAGMENTS(fr) (!((fr)->fr_flags & PFFRAG_NOBUFFER)) 114 115 116 TAILQ_HEAD(pf_fragqueue, pf_fragment) pf_fragqueue; 117 TAILQ_HEAD(pf_cachequeue, pf_fragment) pf_cachequeue; 118 119 static int pf_frag_compare(struct pf_fragment *, 120 struct pf_fragment *); 121 RB_HEAD(pf_frag_tree, pf_fragment) pf_frag_tree, pf_cache_tree; 122 RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 123 RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 124 125 /* Private prototypes */ 126 void pf_ip2key(struct pf_fragment *, struct ip *); 127 void pf_remove_fragment(struct pf_fragment *); 128 void pf_flush_fragments(void); 129 void pf_free_fragment(struct pf_fragment *); 130 struct pf_fragment *pf_find_fragment(struct ip *, struct pf_frag_tree *); 131 struct mbuf *pf_reassemble(struct mbuf **, struct pf_fragment **, 132 struct pf_frent *, int); 133 struct mbuf *pf_fragcache(struct mbuf **, struct ip*, 134 struct pf_fragment **, int, int, int *); 135 u_int16_t pf_cksum_fixup(u_int16_t, u_int16_t, u_int16_t); 136 int pf_normalize_tcpopt(struct pf_rule *, struct mbuf *, 137 struct tcphdr *, int); 138 139 #define DPFPRINTF(x) if (pf_status.debug >= PF_DEBUG_MISC) \ 140 { kprintf("%s: ", __func__); kprintf x ;} 141 142 /* Globals */ 143 vm_zone_t pf_frent_pl, pf_frag_pl, pf_cache_pl, pf_cent_pl; 144 vm_zone_t pf_state_scrub_pl; 145 int pf_nfrents, pf_ncache; 146 147 void 148 pf_normalize_init(void) 149 { 150 /* XXX 151 pool_sethiwat(&pf_frag_pl, PFFRAG_FRAG_HIWAT); 152 pool_sethardlimit(&pf_frent_pl, PFFRAG_FRENT_HIWAT, NULL, 0); 153 pool_sethardlimit(&pf_cache_pl, PFFRAG_FRCACHE_HIWAT, NULL, 0); 154 pool_sethardlimit(&pf_cent_pl, PFFRAG_FRCENT_HIWAT, NULL, 0); 155 */ 156 157 TAILQ_INIT(&pf_fragqueue); 158 TAILQ_INIT(&pf_cachequeue); 159 } 160 161 static int 162 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b) 163 { 164 int diff; 165 166 if ((diff = a->fr_id - b->fr_id)) 167 return (diff); 168 else if ((diff = a->fr_p - b->fr_p)) 169 return (diff); 170 else if (a->fr_src.s_addr < b->fr_src.s_addr) 171 return (-1); 172 else if (a->fr_src.s_addr > b->fr_src.s_addr) 173 return (1); 174 else if (a->fr_dst.s_addr < b->fr_dst.s_addr) 175 return (-1); 176 else if (a->fr_dst.s_addr > b->fr_dst.s_addr) 177 return (1); 178 return (0); 179 } 180 181 void 182 pf_purge_expired_fragments(void) 183 { 184 struct pf_fragment *frag; 185 u_int32_t expire = time_second - 186 pf_default_rule.timeout[PFTM_FRAG]; 187 188 while ((frag = TAILQ_LAST(&pf_fragqueue, pf_fragqueue)) != NULL) { 189 KASSERT((BUFFER_FRAGMENTS(frag)), 190 ("BUFFER_FRAGMENTS(frag) == 0: %s", __func__)); 191 if (frag->fr_timeout > expire) 192 break; 193 194 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); 195 pf_free_fragment(frag); 196 } 197 198 while ((frag = TAILQ_LAST(&pf_cachequeue, pf_cachequeue)) != NULL) { 199 KASSERT((!BUFFER_FRAGMENTS(frag)), 200 ("BUFFER_FRAGMENTS(frag) != 0: %s", __func__)); 201 if (frag->fr_timeout > expire) 202 break; 203 204 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); 205 pf_free_fragment(frag); 206 KASSERT((TAILQ_EMPTY(&pf_cachequeue) || 207 TAILQ_LAST(&pf_cachequeue, pf_cachequeue) != frag), 208 ("!(TAILQ_EMPTY() || TAILQ_LAST() == farg): %s", 209 __func__)); 210 } 211 } 212 213 /* 214 * Try to flush old fragments to make space for new ones 215 */ 216 217 void 218 pf_flush_fragments(void) 219 { 220 struct pf_fragment *frag; 221 int goal; 222 223 goal = pf_nfrents * 9 / 10; 224 DPFPRINTF(("trying to free > %d frents\n", 225 pf_nfrents - goal)); 226 while (goal < pf_nfrents) { 227 frag = TAILQ_LAST(&pf_fragqueue, pf_fragqueue); 228 if (frag == NULL) 229 break; 230 pf_free_fragment(frag); 231 } 232 233 234 goal = pf_ncache * 9 / 10; 235 DPFPRINTF(("trying to free > %d cache entries\n", 236 pf_ncache - goal)); 237 while (goal < pf_ncache) { 238 frag = TAILQ_LAST(&pf_cachequeue, pf_cachequeue); 239 if (frag == NULL) 240 break; 241 pf_free_fragment(frag); 242 } 243 } 244 245 /* Frees the fragments and all associated entries */ 246 247 void 248 pf_free_fragment(struct pf_fragment *frag) 249 { 250 struct pf_frent *frent; 251 struct pf_frcache *frcache; 252 253 /* Free all fragments */ 254 if (BUFFER_FRAGMENTS(frag)) { 255 for (frent = LIST_FIRST(&frag->fr_queue); frent; 256 frent = LIST_FIRST(&frag->fr_queue)) { 257 LIST_REMOVE(frent, fr_next); 258 259 m_freem(frent->fr_m); 260 pool_put(&pf_frent_pl, frent); 261 pf_nfrents--; 262 } 263 } else { 264 for (frcache = LIST_FIRST(&frag->fr_cache); frcache; 265 frcache = LIST_FIRST(&frag->fr_cache)) { 266 LIST_REMOVE(frcache, fr_next); 267 268 KASSERT((LIST_EMPTY(&frag->fr_cache) || 269 LIST_FIRST(&frag->fr_cache)->fr_off > 270 frcache->fr_end), 271 ("! (LIST_EMPTY() || LIST_FIRST()->fr_off >" 272 " frcache->fr_end): %s", __func__)); 273 274 pool_put(&pf_cent_pl, frcache); 275 pf_ncache--; 276 } 277 } 278 279 pf_remove_fragment(frag); 280 } 281 282 void 283 pf_ip2key(struct pf_fragment *key, struct ip *ip) 284 { 285 key->fr_p = ip->ip_p; 286 key->fr_id = ip->ip_id; 287 key->fr_src.s_addr = ip->ip_src.s_addr; 288 key->fr_dst.s_addr = ip->ip_dst.s_addr; 289 } 290 291 struct pf_fragment * 292 pf_find_fragment(struct ip *ip, struct pf_frag_tree *tree) 293 { 294 struct pf_fragment key; 295 struct pf_fragment *frag; 296 297 pf_ip2key(&key, ip); 298 299 frag = RB_FIND(pf_frag_tree, tree, &key); 300 if (frag != NULL) { 301 /* XXX Are we sure we want to update the timeout? */ 302 frag->fr_timeout = time_second; 303 if (BUFFER_FRAGMENTS(frag)) { 304 TAILQ_REMOVE(&pf_fragqueue, frag, frag_next); 305 TAILQ_INSERT_HEAD(&pf_fragqueue, frag, frag_next); 306 } else { 307 TAILQ_REMOVE(&pf_cachequeue, frag, frag_next); 308 TAILQ_INSERT_HEAD(&pf_cachequeue, frag, frag_next); 309 } 310 } 311 312 return (frag); 313 } 314 315 /* Removes a fragment from the fragment queue and frees the fragment */ 316 317 void 318 pf_remove_fragment(struct pf_fragment *frag) 319 { 320 if (BUFFER_FRAGMENTS(frag)) { 321 RB_REMOVE(pf_frag_tree, &pf_frag_tree, frag); 322 TAILQ_REMOVE(&pf_fragqueue, frag, frag_next); 323 pool_put(&pf_frag_pl, frag); 324 } else { 325 RB_REMOVE(pf_frag_tree, &pf_cache_tree, frag); 326 TAILQ_REMOVE(&pf_cachequeue, frag, frag_next); 327 pool_put(&pf_cache_pl, frag); 328 } 329 } 330 331 #define FR_IP_OFF(fr) (((fr)->fr_ip->ip_off & IP_OFFMASK) << 3) 332 struct mbuf * 333 pf_reassemble(struct mbuf **m0, struct pf_fragment **frag, 334 struct pf_frent *frent, int mff) 335 { 336 struct mbuf *m = *m0, *m2; 337 struct pf_frent *frea, *next; 338 struct pf_frent *frep = NULL; 339 struct ip *ip = frent->fr_ip; 340 int hlen = ip->ip_hl << 2; 341 u_int16_t off = (ip->ip_off & IP_OFFMASK) << 3; 342 u_int16_t ip_len = ip->ip_len - ip->ip_hl * 4; 343 u_int16_t max = ip_len + off; 344 345 KASSERT((*frag == NULL || BUFFER_FRAGMENTS(*frag)), 346 ("! (*frag == NULL || BUFFER_FRAGMENTS(*frag)): %s", __func__)); 347 348 /* Strip off ip header */ 349 m->m_data += hlen; 350 m->m_len -= hlen; 351 352 /* Create a new reassembly queue for this packet */ 353 if (*frag == NULL) { 354 *frag = pool_get(&pf_frag_pl, PR_NOWAIT); 355 if (*frag == NULL) { 356 pf_flush_fragments(); 357 *frag = pool_get(&pf_frag_pl, PR_NOWAIT); 358 if (*frag == NULL) 359 goto drop_fragment; 360 } 361 362 (*frag)->fr_flags = 0; 363 (*frag)->fr_max = 0; 364 (*frag)->fr_src = frent->fr_ip->ip_src; 365 (*frag)->fr_dst = frent->fr_ip->ip_dst; 366 (*frag)->fr_p = frent->fr_ip->ip_p; 367 (*frag)->fr_id = frent->fr_ip->ip_id; 368 (*frag)->fr_timeout = time_second; 369 LIST_INIT(&(*frag)->fr_queue); 370 371 RB_INSERT(pf_frag_tree, &pf_frag_tree, *frag); 372 TAILQ_INSERT_HEAD(&pf_fragqueue, *frag, frag_next); 373 374 /* We do not have a previous fragment */ 375 frep = NULL; 376 goto insert; 377 } 378 379 /* 380 * Find a fragment after the current one: 381 * - off contains the real shifted offset. 382 */ 383 LIST_FOREACH(frea, &(*frag)->fr_queue, fr_next) { 384 if (FR_IP_OFF(frea) > off) 385 break; 386 frep = frea; 387 } 388 389 KASSERT((frep != NULL || frea != NULL), 390 ("!(frep != NULL || frea != NULL): %s", __func__)); 391 392 if (frep != NULL && 393 FR_IP_OFF(frep) + frep->fr_ip->ip_len - frep->fr_ip->ip_hl * 394 4 > off) 395 { 396 u_int16_t precut; 397 398 precut = FR_IP_OFF(frep) + frep->fr_ip->ip_len - 399 frep->fr_ip->ip_hl * 4 - off; 400 if (precut >= ip_len) 401 goto drop_fragment; 402 m_adj(frent->fr_m, precut); 403 DPFPRINTF(("overlap -%d\n", precut)); 404 /* Enforce 8 byte boundaries */ 405 ip->ip_off = ip->ip_off + (precut >> 3); 406 off = (ip->ip_off & IP_OFFMASK) << 3; 407 ip_len -= precut; 408 ip->ip_len = ip_len; 409 } 410 411 for (; frea != NULL && ip_len + off > FR_IP_OFF(frea); 412 frea = next) 413 { 414 u_int16_t aftercut; 415 416 aftercut = ip_len + off - FR_IP_OFF(frea); 417 DPFPRINTF(("adjust overlap %d\n", aftercut)); 418 if (aftercut < frea->fr_ip->ip_len - frea->fr_ip->ip_hl 419 * 4) 420 { 421 frea->fr_ip->ip_len = 422 frea->fr_ip->ip_len - aftercut; 423 frea->fr_ip->ip_off = frea->fr_ip->ip_off + 424 (aftercut >> 3); 425 m_adj(frea->fr_m, aftercut); 426 break; 427 } 428 429 /* This fragment is completely overlapped, loose it */ 430 next = LIST_NEXT(frea, fr_next); 431 m_freem(frea->fr_m); 432 LIST_REMOVE(frea, fr_next); 433 pool_put(&pf_frent_pl, frea); 434 pf_nfrents--; 435 } 436 437 insert: 438 /* Update maximum data size */ 439 if ((*frag)->fr_max < max) 440 (*frag)->fr_max = max; 441 /* This is the last segment */ 442 if (!mff) 443 (*frag)->fr_flags |= PFFRAG_SEENLAST; 444 445 if (frep == NULL) 446 LIST_INSERT_HEAD(&(*frag)->fr_queue, frent, fr_next); 447 else 448 LIST_INSERT_AFTER(frep, frent, fr_next); 449 450 /* Check if we are completely reassembled */ 451 if (!((*frag)->fr_flags & PFFRAG_SEENLAST)) 452 return (NULL); 453 454 /* Check if we have all the data */ 455 off = 0; 456 for (frep = LIST_FIRST(&(*frag)->fr_queue); frep; frep = next) { 457 next = LIST_NEXT(frep, fr_next); 458 459 off += frep->fr_ip->ip_len - frep->fr_ip->ip_hl * 4; 460 if (off < (*frag)->fr_max && 461 (next == NULL || FR_IP_OFF(next) != off)) 462 { 463 DPFPRINTF(("missing fragment at %d, next %d, max %d\n", 464 off, next == NULL ? -1 : FR_IP_OFF(next), 465 (*frag)->fr_max)); 466 return (NULL); 467 } 468 } 469 DPFPRINTF(("%d < %d?\n", off, (*frag)->fr_max)); 470 if (off < (*frag)->fr_max) 471 return (NULL); 472 473 /* We have all the data */ 474 frent = LIST_FIRST(&(*frag)->fr_queue); 475 KASSERT((frent != NULL), ("frent == NULL: %s", __func__)); 476 if ((frent->fr_ip->ip_hl << 2) + off > IP_MAXPACKET) { 477 DPFPRINTF(("drop: too big: %d\n", off)); 478 pf_free_fragment(*frag); 479 *frag = NULL; 480 return (NULL); 481 } 482 next = LIST_NEXT(frent, fr_next); 483 484 /* Magic from ip_input */ 485 ip = frent->fr_ip; 486 m = frent->fr_m; 487 m2 = m->m_next; 488 m->m_next = NULL; 489 m_cat(m, m2); 490 pool_put(&pf_frent_pl, frent); 491 pf_nfrents--; 492 for (frent = next; frent != NULL; frent = next) { 493 next = LIST_NEXT(frent, fr_next); 494 495 m2 = frent->fr_m; 496 pool_put(&pf_frent_pl, frent); 497 pf_nfrents--; 498 m->m_pkthdr.csum_flags &= m2->m_pkthdr.csum_flags; 499 m->m_pkthdr.csum_data += m2->m_pkthdr.csum_data; 500 m_cat(m, m2); 501 } 502 503 /* 504 * Note: this 1's complement optimization with <= 65535 fragments. 505 * 506 * Handle 1's complement carry for the 16 bit result. This can 507 * result in another carry which must also be handled. 508 */ 509 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) + 510 (m->m_pkthdr.csum_data >> 16); 511 if (m->m_pkthdr.csum_data > 0xFFFF) 512 m->m_pkthdr.csum_data -= 0xFFFF; 513 514 515 ip->ip_src = (*frag)->fr_src; 516 ip->ip_dst = (*frag)->fr_dst; 517 518 /* Remove from fragment queue */ 519 pf_remove_fragment(*frag); 520 *frag = NULL; 521 522 hlen = ip->ip_hl << 2; 523 ip->ip_len = off + hlen; 524 m->m_len += hlen; 525 m->m_data -= hlen; 526 527 /* some debugging cruft by sklower, below, will go away soon */ 528 /* XXX this should be done elsewhere */ 529 if (m->m_flags & M_PKTHDR) { 530 int plen = 0; 531 for (m2 = m; m2; m2 = m2->m_next) 532 plen += m2->m_len; 533 m->m_pkthdr.len = plen; 534 } 535 536 DPFPRINTF(("complete: %p(%d)\n", m, ip->ip_len)); 537 return (m); 538 539 drop_fragment: 540 /* Oops - fail safe - drop packet */ 541 pool_put(&pf_frent_pl, frent); 542 pf_nfrents--; 543 m_freem(m); 544 return (NULL); 545 } 546 547 struct mbuf * 548 pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff, 549 int drop, int *nomem) 550 { 551 struct mbuf *m = *m0; 552 struct pf_frcache *frp, *fra, *cur = NULL; 553 int ip_len = h->ip_len - (h->ip_hl << 2); 554 u_int16_t off = h->ip_off << 3; 555 u_int16_t max = ip_len + off; 556 int hosed = 0; 557 558 KASSERT((*frag == NULL || !BUFFER_FRAGMENTS(*frag)), 559 ("!(*frag == NULL || !BUFFER_FRAGMENTS(*frag)): %s", __func__)); 560 561 /* Create a new range queue for this packet */ 562 if (*frag == NULL) { 563 *frag = pool_get(&pf_cache_pl, PR_NOWAIT); 564 if (*frag == NULL) { 565 pf_flush_fragments(); 566 *frag = pool_get(&pf_cache_pl, PR_NOWAIT); 567 if (*frag == NULL) 568 goto no_mem; 569 } 570 571 /* Get an entry for the queue */ 572 cur = pool_get(&pf_cent_pl, PR_NOWAIT); 573 if (cur == NULL) { 574 pool_put(&pf_cache_pl, *frag); 575 *frag = NULL; 576 goto no_mem; 577 } 578 pf_ncache++; 579 580 (*frag)->fr_flags = PFFRAG_NOBUFFER; 581 (*frag)->fr_max = 0; 582 (*frag)->fr_src = h->ip_src; 583 (*frag)->fr_dst = h->ip_dst; 584 (*frag)->fr_p = h->ip_p; 585 (*frag)->fr_id = h->ip_id; 586 (*frag)->fr_timeout = time_second; 587 588 cur->fr_off = off; 589 cur->fr_end = max; 590 LIST_INIT(&(*frag)->fr_cache); 591 LIST_INSERT_HEAD(&(*frag)->fr_cache, cur, fr_next); 592 593 RB_INSERT(pf_frag_tree, &pf_cache_tree, *frag); 594 TAILQ_INSERT_HEAD(&pf_cachequeue, *frag, frag_next); 595 596 DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max)); 597 598 goto pass; 599 } 600 601 /* 602 * Find a fragment after the current one: 603 * - off contains the real shifted offset. 604 */ 605 frp = NULL; 606 LIST_FOREACH(fra, &(*frag)->fr_cache, fr_next) { 607 if (fra->fr_off > off) 608 break; 609 frp = fra; 610 } 611 612 KASSERT((frp != NULL || fra != NULL), 613 ("!(frp != NULL || fra != NULL): %s", __func__)); 614 615 if (frp != NULL) { 616 int precut; 617 618 precut = frp->fr_end - off; 619 if (precut >= ip_len) { 620 /* Fragment is entirely a duplicate */ 621 DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n", 622 h->ip_id, frp->fr_off, frp->fr_end, off, max)); 623 goto drop_fragment; 624 } 625 if (precut == 0) { 626 /* They are adjacent. Fixup cache entry */ 627 DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n", 628 h->ip_id, frp->fr_off, frp->fr_end, off, max)); 629 frp->fr_end = max; 630 } else if (precut > 0) { 631 /* The first part of this payload overlaps with a 632 * fragment that has already been passed. 633 * Need to trim off the first part of the payload. 634 * But to do so easily, we need to create another 635 * mbuf to throw the original header into. 636 */ 637 638 DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n", 639 h->ip_id, precut, frp->fr_off, frp->fr_end, off, 640 max)); 641 642 off += precut; 643 max -= precut; 644 /* Update the previous frag to encompass this one */ 645 frp->fr_end = max; 646 647 if (!drop) { 648 /* XXX Optimization opportunity 649 * This is a very heavy way to trim the payload. 650 * we could do it much faster by diddling mbuf 651 * internals but that would be even less legible 652 * than this mbuf magic. For my next trick, 653 * I'll pull a rabbit out of my laptop. 654 */ 655 *m0 = m_dup(m, MB_DONTWAIT); 656 /* From KAME Project : We have missed this! */ 657 m_adj(*m0, (h->ip_hl << 2) - 658 (*m0)->m_pkthdr.len); 659 if (*m0 == NULL) 660 goto no_mem; 661 KASSERT(((*m0)->m_next == NULL), 662 ("(*m0)->m_next != NULL: %s", 663 __func__)); 664 m_adj(m, precut + (h->ip_hl << 2)); 665 m_cat(*m0, m); 666 m = *m0; 667 if (m->m_flags & M_PKTHDR) { 668 int plen = 0; 669 struct mbuf *t; 670 for (t = m; t; t = t->m_next) 671 plen += t->m_len; 672 m->m_pkthdr.len = plen; 673 } 674 675 676 h = mtod(m, struct ip *); 677 678 KASSERT(((int)m->m_len == 679 h->ip_len - precut), 680 ("m->m_len != h->ip_len - precut: %s", 681 __func__)); 682 h->ip_off = h->ip_off + 683 (precut >> 3); 684 h->ip_len = h->ip_len - precut; 685 } else { 686 hosed++; 687 } 688 } else { 689 /* There is a gap between fragments */ 690 691 DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n", 692 h->ip_id, -precut, frp->fr_off, frp->fr_end, off, 693 max)); 694 695 cur = pool_get(&pf_cent_pl, PR_NOWAIT); 696 if (cur == NULL) 697 goto no_mem; 698 pf_ncache++; 699 700 cur->fr_off = off; 701 cur->fr_end = max; 702 LIST_INSERT_AFTER(frp, cur, fr_next); 703 } 704 } 705 706 if (fra != NULL) { 707 int aftercut; 708 int merge = 0; 709 710 aftercut = max - fra->fr_off; 711 if (aftercut == 0) { 712 /* Adjacent fragments */ 713 DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n", 714 h->ip_id, off, max, fra->fr_off, fra->fr_end)); 715 fra->fr_off = off; 716 merge = 1; 717 } else if (aftercut > 0) { 718 /* Need to chop off the tail of this fragment */ 719 DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n", 720 h->ip_id, aftercut, off, max, fra->fr_off, 721 fra->fr_end)); 722 fra->fr_off = off; 723 max -= aftercut; 724 725 merge = 1; 726 727 if (!drop) { 728 m_adj(m, -aftercut); 729 if (m->m_flags & M_PKTHDR) { 730 int plen = 0; 731 struct mbuf *t; 732 for (t = m; t; t = t->m_next) 733 plen += t->m_len; 734 m->m_pkthdr.len = plen; 735 } 736 h = mtod(m, struct ip *); 737 KASSERT(((int)m->m_len == h->ip_len - aftercut), 738 ("m->m_len != h->ip_len - aftercut: %s", 739 __func__)); 740 h->ip_len = h->ip_len - aftercut; 741 } else { 742 hosed++; 743 } 744 } else if (frp == NULL) { 745 /* There is a gap between fragments */ 746 DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n", 747 h->ip_id, -aftercut, off, max, fra->fr_off, 748 fra->fr_end)); 749 750 cur = pool_get(&pf_cent_pl, PR_NOWAIT); 751 if (cur == NULL) 752 goto no_mem; 753 pf_ncache++; 754 755 cur->fr_off = off; 756 cur->fr_end = max; 757 LIST_INSERT_BEFORE(fra, cur, fr_next); 758 } 759 760 761 /* Need to glue together two separate fragment descriptors */ 762 if (merge) { 763 if (cur && fra->fr_off <= cur->fr_end) { 764 /* Need to merge in a previous 'cur' */ 765 DPFPRINTF(("fragcache[%d]: adjacent(merge " 766 "%d-%d) %d-%d (%d-%d)\n", 767 h->ip_id, cur->fr_off, cur->fr_end, off, 768 max, fra->fr_off, fra->fr_end)); 769 fra->fr_off = cur->fr_off; 770 LIST_REMOVE(cur, fr_next); 771 pool_put(&pf_cent_pl, cur); 772 pf_ncache--; 773 cur = NULL; 774 775 } else if (frp && fra->fr_off <= frp->fr_end) { 776 /* Need to merge in a modified 'frp' */ 777 KASSERT((cur == NULL), ("cur != NULL: %s", 778 __func__)); 779 DPFPRINTF(("fragcache[%d]: adjacent(merge " 780 "%d-%d) %d-%d (%d-%d)\n", 781 h->ip_id, frp->fr_off, frp->fr_end, off, 782 max, fra->fr_off, fra->fr_end)); 783 fra->fr_off = frp->fr_off; 784 LIST_REMOVE(frp, fr_next); 785 pool_put(&pf_cent_pl, frp); 786 pf_ncache--; 787 frp = NULL; 788 789 } 790 } 791 } 792 793 if (hosed) { 794 /* 795 * We must keep tracking the overall fragment even when 796 * we're going to drop it anyway so that we know when to 797 * free the overall descriptor. Thus we drop the frag late. 798 */ 799 goto drop_fragment; 800 } 801 802 803 pass: 804 /* Update maximum data size */ 805 if ((*frag)->fr_max < max) 806 (*frag)->fr_max = max; 807 808 /* This is the last segment */ 809 if (!mff) 810 (*frag)->fr_flags |= PFFRAG_SEENLAST; 811 812 /* Check if we are completely reassembled */ 813 if (((*frag)->fr_flags & PFFRAG_SEENLAST) && 814 LIST_FIRST(&(*frag)->fr_cache)->fr_off == 0 && 815 LIST_FIRST(&(*frag)->fr_cache)->fr_end == (*frag)->fr_max) { 816 /* Remove from fragment queue */ 817 DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id, 818 (*frag)->fr_max)); 819 pf_free_fragment(*frag); 820 *frag = NULL; 821 } 822 823 return (m); 824 825 no_mem: 826 *nomem = 1; 827 828 /* Still need to pay attention to !IP_MF */ 829 if (!mff && *frag != NULL) 830 (*frag)->fr_flags |= PFFRAG_SEENLAST; 831 832 m_freem(m); 833 return (NULL); 834 835 drop_fragment: 836 837 /* Still need to pay attention to !IP_MF */ 838 if (!mff && *frag != NULL) 839 (*frag)->fr_flags |= PFFRAG_SEENLAST; 840 841 if (drop) { 842 /* This fragment has been deemed bad. Don't reass */ 843 if (((*frag)->fr_flags & PFFRAG_DROP) == 0) 844 DPFPRINTF(("fragcache[%d]: dropping overall fragment\n", 845 h->ip_id)); 846 (*frag)->fr_flags |= PFFRAG_DROP; 847 } 848 849 m_freem(m); 850 return (NULL); 851 } 852 853 int 854 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason) 855 { 856 struct mbuf *m = *m0; 857 struct pf_rule *r; 858 struct pf_frent *frent; 859 struct pf_fragment *frag = NULL; 860 struct ip *h = mtod(m, struct ip *); 861 int mff = (h->ip_off & IP_MF); 862 int hlen = h->ip_hl << 2; 863 u_int16_t fragoff = (h->ip_off & IP_OFFMASK) << 3; 864 u_int16_t max; 865 int ip_len; 866 int ip_off; 867 868 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 869 while (r != NULL) { 870 r->evaluations++; 871 if (r->kif != NULL && 872 (r->kif != kif && r->kif != kif->pfik_parent) == !r->ifnot) 873 r = r->skip[PF_SKIP_IFP].ptr; 874 else if (r->direction && r->direction != dir) 875 r = r->skip[PF_SKIP_DIR].ptr; 876 else if (r->af && r->af != AF_INET) 877 r = r->skip[PF_SKIP_AF].ptr; 878 else if (r->proto && r->proto != h->ip_p) 879 r = r->skip[PF_SKIP_PROTO].ptr; 880 else if (PF_MISMATCHAW(&r->src.addr, 881 (struct pf_addr *)&h->ip_src.s_addr, AF_INET, r->src.not)) 882 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 883 else if (PF_MISMATCHAW(&r->dst.addr, 884 (struct pf_addr *)&h->ip_dst.s_addr, AF_INET, r->dst.not)) 885 r = r->skip[PF_SKIP_DST_ADDR].ptr; 886 else 887 break; 888 } 889 890 if (r == NULL) 891 return (PF_PASS); 892 else 893 r->packets++; 894 895 /* Check for illegal packets */ 896 if (hlen < (int)sizeof(struct ip)) 897 goto drop; 898 899 if (hlen > h->ip_len) 900 goto drop; 901 902 /* Clear IP_DF if the rule uses the no-df option */ 903 if (r->rule_flag & PFRULE_NODF) 904 h->ip_off &= ~IP_DF; 905 906 /* We will need other tests here */ 907 if (!fragoff && !mff) 908 goto no_fragment; 909 910 /* We're dealing with a fragment now. Don't allow fragments 911 * with IP_DF to enter the cache. If the flag was cleared by 912 * no-df above, fine. Otherwise drop it. 913 */ 914 if (h->ip_off & IP_DF) { 915 DPFPRINTF(("IP_DF\n")); 916 goto bad; 917 } 918 919 ip_len = h->ip_len - hlen; 920 ip_off = (h->ip_off & IP_OFFMASK) << 3; 921 922 /* All fragments are 8 byte aligned */ 923 if (mff && (ip_len & 0x7)) { 924 DPFPRINTF(("mff and %d\n", ip_len)); 925 goto bad; 926 } 927 928 /* Respect maximum length */ 929 if (fragoff + ip_len > IP_MAXPACKET) { 930 DPFPRINTF(("max packet %d\n", fragoff + ip_len)); 931 goto bad; 932 } 933 max = fragoff + ip_len; 934 935 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) { 936 /* Fully buffer all of the fragments */ 937 938 frag = pf_find_fragment(h, &pf_frag_tree); 939 940 /* Check if we saw the last fragment already */ 941 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 942 max > frag->fr_max) 943 goto bad; 944 945 /* Get an entry for the fragment queue */ 946 frent = pool_get(&pf_frent_pl, PR_NOWAIT); 947 if (frent == NULL) { 948 REASON_SET(reason, PFRES_MEMORY); 949 return (PF_DROP); 950 } 951 pf_nfrents++; 952 frent->fr_ip = h; 953 frent->fr_m = m; 954 955 /* Might return a completely reassembled mbuf, or NULL */ 956 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max)); 957 *m0 = m = pf_reassemble(m0, &frag, frent, mff); 958 959 if (m == NULL) 960 return (PF_DROP); 961 962 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP)) 963 goto drop; 964 965 h = mtod(m, struct ip *); 966 } else { 967 /* non-buffering fragment cache (drops or masks overlaps) */ 968 int nomem = 0; 969 970 if (dir == PF_OUT) { 971 if (m->m_pkthdr.fw_flags & PF_MBUF_FRAGCACHE) { 972 /* Already passed the fragment cache in the 973 * input direction. If we continued, it would 974 * appear to be a dup and would be dropped. 975 */ 976 goto fragment_pass; 977 } 978 } 979 980 frag = pf_find_fragment(h, &pf_cache_tree); 981 982 /* Check if we saw the last fragment already */ 983 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 984 max > frag->fr_max) { 985 if (r->rule_flag & PFRULE_FRAGDROP) 986 frag->fr_flags |= PFFRAG_DROP; 987 goto bad; 988 } 989 990 *m0 = m = pf_fragcache(m0, h, &frag, mff, 991 (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem); 992 if (m == NULL) { 993 if (nomem) 994 goto no_mem; 995 goto drop; 996 } 997 998 if (dir == PF_IN) 999 m->m_pkthdr.fw_flags |= PF_MBUF_FRAGCACHE; 1000 1001 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP)) 1002 goto drop; 1003 goto fragment_pass; 1004 } 1005 1006 no_fragment: 1007 /* At this point, only IP_DF is allowed in ip_off */ 1008 h->ip_off &= IP_DF; 1009 1010 /* Enforce a minimum ttl, may cause endless packet loops */ 1011 if (r->min_ttl && h->ip_ttl < r->min_ttl) 1012 h->ip_ttl = r->min_ttl; 1013 1014 if (r->rule_flag & PFRULE_RANDOMID) { 1015 #ifdef RANDOM_IP_ID 1016 h->ip_id = ip_randomid(); 1017 #else 1018 h->ip_id = htons(ip_id++); 1019 #endif 1020 } 1021 1022 return (PF_PASS); 1023 1024 fragment_pass: 1025 /* Enforce a minimum ttl, may cause endless packet loops */ 1026 if (r->min_ttl && h->ip_ttl < r->min_ttl) 1027 h->ip_ttl = r->min_ttl; 1028 1029 return (PF_PASS); 1030 1031 no_mem: 1032 REASON_SET(reason, PFRES_MEMORY); 1033 if (r != NULL && r->log) 1034 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL); 1035 return (PF_DROP); 1036 1037 drop: 1038 REASON_SET(reason, PFRES_NORM); 1039 if (r != NULL && r->log) 1040 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL); 1041 return (PF_DROP); 1042 1043 bad: 1044 DPFPRINTF(("dropping bad fragment\n")); 1045 1046 /* Free associated fragments */ 1047 if (frag != NULL) 1048 pf_free_fragment(frag); 1049 1050 REASON_SET(reason, PFRES_FRAG); 1051 if (r != NULL && r->log) 1052 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL); 1053 1054 return (PF_DROP); 1055 } 1056 1057 #ifdef INET6 1058 int 1059 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif, 1060 u_short *reason) 1061 { 1062 struct mbuf *m = *m0; 1063 struct pf_rule *r; 1064 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1065 int off; 1066 struct ip6_ext ext; 1067 struct ip6_opt opt; 1068 struct ip6_opt_jumbo jumbo; 1069 struct ip6_frag frag; 1070 u_int32_t jumbolen = 0, plen; 1071 u_int16_t fragoff = 0; 1072 int optend; 1073 int ooff; 1074 u_int8_t proto; 1075 int terminal; 1076 1077 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1078 while (r != NULL) { 1079 r->evaluations++; 1080 if (r->kif != NULL && 1081 (r->kif != kif && r->kif != kif->pfik_parent) == !r->ifnot) 1082 r = r->skip[PF_SKIP_IFP].ptr; 1083 else if (r->direction && r->direction != dir) 1084 r = r->skip[PF_SKIP_DIR].ptr; 1085 else if (r->af && r->af != AF_INET6) 1086 r = r->skip[PF_SKIP_AF].ptr; 1087 #if 0 /* header chain! */ 1088 else if (r->proto && r->proto != h->ip6_nxt) 1089 r = r->skip[PF_SKIP_PROTO].ptr; 1090 #endif 1091 else if (PF_MISMATCHAW(&r->src.addr, 1092 (struct pf_addr *)&h->ip6_src, AF_INET6, r->src.not)) 1093 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1094 else if (PF_MISMATCHAW(&r->dst.addr, 1095 (struct pf_addr *)&h->ip6_dst, AF_INET6, r->dst.not)) 1096 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1097 else 1098 break; 1099 } 1100 1101 if (r == NULL) 1102 return (PF_PASS); 1103 else 1104 r->packets++; 1105 1106 /* Check for illegal packets */ 1107 if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len) 1108 goto drop; 1109 1110 off = sizeof(struct ip6_hdr); 1111 proto = h->ip6_nxt; 1112 terminal = 0; 1113 do { 1114 switch (proto) { 1115 case IPPROTO_FRAGMENT: 1116 goto fragment; 1117 break; 1118 case IPPROTO_AH: 1119 case IPPROTO_ROUTING: 1120 case IPPROTO_DSTOPTS: 1121 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1122 NULL, AF_INET6)) 1123 goto shortpkt; 1124 if (proto == IPPROTO_AH) 1125 off += (ext.ip6e_len + 2) * 4; 1126 else 1127 off += (ext.ip6e_len + 1) * 8; 1128 proto = ext.ip6e_nxt; 1129 break; 1130 case IPPROTO_HOPOPTS: 1131 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1132 NULL, AF_INET6)) 1133 goto shortpkt; 1134 optend = off + (ext.ip6e_len + 1) * 8; 1135 ooff = off + sizeof(ext); 1136 do { 1137 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type, 1138 sizeof(opt.ip6o_type), NULL, NULL, 1139 AF_INET6)) 1140 goto shortpkt; 1141 if (opt.ip6o_type == IP6OPT_PAD1) { 1142 ooff++; 1143 continue; 1144 } 1145 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt), 1146 NULL, NULL, AF_INET6)) 1147 goto shortpkt; 1148 if (ooff + sizeof(opt) + opt.ip6o_len > optend) 1149 goto drop; 1150 switch (opt.ip6o_type) { 1151 case IP6OPT_JUMBO: 1152 if (h->ip6_plen != 0) 1153 goto drop; 1154 if (!pf_pull_hdr(m, ooff, &jumbo, 1155 sizeof(jumbo), NULL, NULL, 1156 AF_INET6)) 1157 goto shortpkt; 1158 memcpy(&jumbolen, jumbo.ip6oj_jumbo_len, 1159 sizeof(jumbolen)); 1160 jumbolen = ntohl(jumbolen); 1161 if (jumbolen <= IPV6_MAXPACKET) 1162 goto drop; 1163 if (sizeof(struct ip6_hdr) + jumbolen != 1164 m->m_pkthdr.len) 1165 goto drop; 1166 break; 1167 default: 1168 break; 1169 } 1170 ooff += sizeof(opt) + opt.ip6o_len; 1171 } while (ooff < optend); 1172 1173 off = optend; 1174 proto = ext.ip6e_nxt; 1175 break; 1176 default: 1177 terminal = 1; 1178 break; 1179 } 1180 } while (!terminal); 1181 1182 /* jumbo payload option must be present, or plen > 0 */ 1183 if (ntohs(h->ip6_plen) == 0) 1184 plen = jumbolen; 1185 else 1186 plen = ntohs(h->ip6_plen); 1187 if (plen == 0) 1188 goto drop; 1189 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1190 goto shortpkt; 1191 1192 /* Enforce a minimum ttl, may cause endless packet loops */ 1193 if (r->min_ttl && h->ip6_hlim < r->min_ttl) 1194 h->ip6_hlim = r->min_ttl; 1195 1196 return (PF_PASS); 1197 1198 fragment: 1199 if (ntohs(h->ip6_plen) == 0 || jumbolen) 1200 goto drop; 1201 plen = ntohs(h->ip6_plen); 1202 1203 if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6)) 1204 goto shortpkt; 1205 fragoff = ntohs(frag.ip6f_offlg & IP6F_OFF_MASK); 1206 if (fragoff + (plen - off - sizeof(frag)) > IPV6_MAXPACKET) 1207 goto badfrag; 1208 1209 /* do something about it */ 1210 return (PF_PASS); 1211 1212 shortpkt: 1213 REASON_SET(reason, PFRES_SHORT); 1214 if (r != NULL && r->log) 1215 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL); 1216 return (PF_DROP); 1217 1218 drop: 1219 REASON_SET(reason, PFRES_NORM); 1220 if (r != NULL && r->log) 1221 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL); 1222 return (PF_DROP); 1223 1224 badfrag: 1225 REASON_SET(reason, PFRES_FRAG); 1226 if (r != NULL && r->log) 1227 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL); 1228 return (PF_DROP); 1229 } 1230 #endif 1231 1232 int 1233 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff, 1234 int off, void *h, struct pf_pdesc *pd) 1235 { 1236 struct pf_rule *r, *rm = NULL; 1237 struct tcphdr *th = pd->hdr.tcp; 1238 int rewrite = 0; 1239 u_short reason; 1240 u_int8_t flags; 1241 sa_family_t af = pd->af; 1242 1243 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1244 while (r != NULL) { 1245 r->evaluations++; 1246 if (r->kif != NULL && 1247 (r->kif != kif && r->kif != kif->pfik_parent) == !r->ifnot) 1248 r = r->skip[PF_SKIP_IFP].ptr; 1249 else if (r->direction && r->direction != dir) 1250 r = r->skip[PF_SKIP_DIR].ptr; 1251 else if (r->af && r->af != af) 1252 r = r->skip[PF_SKIP_AF].ptr; 1253 else if (r->proto && r->proto != pd->proto) 1254 r = r->skip[PF_SKIP_PROTO].ptr; 1255 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, r->src.not)) 1256 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1257 else if (r->src.port_op && !pf_match_port(r->src.port_op, 1258 r->src.port[0], r->src.port[1], th->th_sport)) 1259 r = r->skip[PF_SKIP_SRC_PORT].ptr; 1260 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, r->dst.not)) 1261 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1262 else if (r->dst.port_op && !pf_match_port(r->dst.port_op, 1263 r->dst.port[0], r->dst.port[1], th->th_dport)) 1264 r = r->skip[PF_SKIP_DST_PORT].ptr; 1265 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match( 1266 pf_osfp_fingerprint(pd, m, off, th), 1267 r->os_fingerprint)) 1268 r = TAILQ_NEXT(r, entries); 1269 else { 1270 rm = r; 1271 break; 1272 } 1273 } 1274 1275 if (rm == NULL) 1276 return (PF_PASS); 1277 else 1278 r->packets++; 1279 1280 if (rm->rule_flag & PFRULE_REASSEMBLE_TCP) 1281 pd->flags |= PFDESC_TCP_NORM; 1282 1283 flags = th->th_flags; 1284 if (flags & TH_SYN) { 1285 /* Illegal packet */ 1286 if (flags & TH_RST) 1287 goto tcp_drop; 1288 1289 if (flags & TH_FIN) 1290 flags &= ~TH_FIN; 1291 } else { 1292 /* Illegal packet */ 1293 if (!(flags & (TH_ACK|TH_RST))) 1294 goto tcp_drop; 1295 } 1296 1297 if (!(flags & TH_ACK)) { 1298 /* These flags are only valid if ACK is set */ 1299 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG)) 1300 goto tcp_drop; 1301 } 1302 1303 /* Check for illegal header length */ 1304 if (th->th_off < (sizeof(struct tcphdr) >> 2)) 1305 goto tcp_drop; 1306 1307 /* If flags changed, or reserved data set, then adjust */ 1308 if (flags != th->th_flags || th->th_x2 != 0) { 1309 u_int16_t ov, nv; 1310 1311 ov = *(u_int16_t *)(&th->th_ack + 1); 1312 th->th_flags = flags; 1313 th->th_x2 = 0; 1314 nv = *(u_int16_t *)(&th->th_ack + 1); 1315 1316 th->th_sum = pf_cksum_fixup(th->th_sum, ov, nv); 1317 rewrite = 1; 1318 } 1319 1320 /* Remove urgent pointer, if TH_URG is not set */ 1321 if (!(flags & TH_URG) && th->th_urp) { 1322 th->th_sum = pf_cksum_fixup(th->th_sum, th->th_urp, 0); 1323 th->th_urp = 0; 1324 rewrite = 1; 1325 } 1326 1327 /* Process options */ 1328 if (r->max_mss && pf_normalize_tcpopt(r, m, th, off)) 1329 rewrite = 1; 1330 1331 /* copy back packet headers if we sanitized */ 1332 if (rewrite) 1333 m_copyback(m, off, sizeof(*th), (caddr_t)th); 1334 1335 return (PF_PASS); 1336 1337 tcp_drop: 1338 REASON_SET(&reason, PFRES_NORM); 1339 if (rm != NULL && r->log) 1340 PFLOG_PACKET(kif, h, m, AF_INET, dir, reason, r, NULL, NULL); 1341 return (PF_DROP); 1342 } 1343 1344 int 1345 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd, 1346 struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst) 1347 { 1348 u_int8_t hdr[60]; 1349 u_int8_t *opt; 1350 1351 KASSERT((src->scrub == NULL), 1352 ("pf_normalize_tcp_init: src->scrub != NULL")); 1353 1354 src->scrub = pool_get(&pf_state_scrub_pl, PR_NOWAIT); 1355 if (src->scrub == NULL) 1356 return (1); 1357 bzero(src->scrub, sizeof(*src->scrub)); 1358 1359 switch (pd->af) { 1360 #ifdef INET 1361 case AF_INET: { 1362 struct ip *h = mtod(m, struct ip *); 1363 src->scrub->pfss_ttl = h->ip_ttl; 1364 break; 1365 } 1366 #endif /* INET */ 1367 #ifdef INET6 1368 case AF_INET6: { 1369 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1370 src->scrub->pfss_ttl = h->ip6_hlim; 1371 break; 1372 } 1373 #endif /* INET6 */ 1374 } 1375 1376 1377 /* 1378 * All normalizations below are only begun if we see the start of 1379 * the connections. They must all set an enabled bit in pfss_flags 1380 */ 1381 if ((th->th_flags & TH_SYN) == 0) 1382 return (0); 1383 1384 1385 if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub && 1386 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1387 /* Diddle with TCP options */ 1388 int hlen; 1389 opt = hdr + sizeof(struct tcphdr); 1390 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1391 while (hlen >= TCPOLEN_TIMESTAMP) { 1392 switch (*opt) { 1393 case TCPOPT_EOL: /* FALLTHROUGH */ 1394 case TCPOPT_NOP: 1395 opt++; 1396 hlen--; 1397 break; 1398 case TCPOPT_TIMESTAMP: 1399 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1400 src->scrub->pfss_flags |= 1401 PFSS_TIMESTAMP; 1402 src->scrub->pfss_ts_mod = karc4random(); 1403 } 1404 /* FALLTHROUGH */ 1405 default: 1406 hlen -= MAX(opt[1], 2); 1407 opt += MAX(opt[1], 2); 1408 break; 1409 } 1410 } 1411 } 1412 1413 return (0); 1414 } 1415 1416 void 1417 pf_normalize_tcp_cleanup(struct pf_state *state) 1418 { 1419 if (state->src.scrub) 1420 pool_put(&pf_state_scrub_pl, state->src.scrub); 1421 if (state->dst.scrub) 1422 pool_put(&pf_state_scrub_pl, state->dst.scrub); 1423 1424 /* Someday... flush the TCP segment reassembly descriptors. */ 1425 } 1426 1427 int 1428 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd, 1429 u_short *reason, struct tcphdr *th, struct pf_state_peer *src, 1430 struct pf_state_peer *dst, int *writeback) 1431 { 1432 u_int8_t hdr[60]; 1433 u_int8_t *opt; 1434 int copyback = 0; 1435 1436 KASSERT((src->scrub || dst->scrub), 1437 ("pf_normalize_tcp_statefull: src->scrub && dst->scrub!")); 1438 1439 /* 1440 * Enforce the minimum TTL seen for this connection. Negate a common 1441 * technique to evade an intrusion detection system and confuse 1442 * firewall state code. 1443 */ 1444 switch (pd->af) { 1445 #ifdef INET 1446 case AF_INET: { 1447 if (src->scrub) { 1448 struct ip *h = mtod(m, struct ip *); 1449 if (h->ip_ttl > src->scrub->pfss_ttl) 1450 src->scrub->pfss_ttl = h->ip_ttl; 1451 h->ip_ttl = src->scrub->pfss_ttl; 1452 } 1453 break; 1454 } 1455 #endif /* INET */ 1456 #ifdef INET6 1457 case AF_INET6: { 1458 if (src->scrub) { 1459 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1460 if (h->ip6_hlim > src->scrub->pfss_ttl) 1461 src->scrub->pfss_ttl = h->ip6_hlim; 1462 h->ip6_hlim = src->scrub->pfss_ttl; 1463 } 1464 break; 1465 } 1466 #endif /* INET6 */ 1467 } 1468 1469 if (th->th_off > (sizeof(struct tcphdr) >> 2) && 1470 ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) || 1471 (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) && 1472 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1473 /* Diddle with TCP options */ 1474 int hlen; 1475 opt = hdr + sizeof(struct tcphdr); 1476 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1477 while (hlen >= TCPOLEN_TIMESTAMP) { 1478 switch (*opt) { 1479 case TCPOPT_EOL: /* FALLTHROUGH */ 1480 case TCPOPT_NOP: 1481 opt++; 1482 hlen--; 1483 break; 1484 case TCPOPT_TIMESTAMP: 1485 /* Modulate the timestamps. Can be used for 1486 * NAT detection, OS uptime determination or 1487 * reboot detection. 1488 */ 1489 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1490 u_int32_t ts_value; 1491 if (src->scrub && 1492 (src->scrub->pfss_flags & 1493 PFSS_TIMESTAMP)) { 1494 memcpy(&ts_value, &opt[2], 1495 sizeof(u_int32_t)); 1496 ts_value = htonl(ntohl(ts_value) 1497 + src->scrub->pfss_ts_mod); 1498 pf_change_a(&opt[2], 1499 &th->th_sum, ts_value, 0); 1500 copyback = 1; 1501 } 1502 1503 /* Modulate TS reply iff valid (!0) */ 1504 memcpy(&ts_value, &opt[6], 1505 sizeof(u_int32_t)); 1506 if (ts_value && dst->scrub && 1507 (dst->scrub->pfss_flags & 1508 PFSS_TIMESTAMP)) { 1509 ts_value = htonl(ntohl(ts_value) 1510 - dst->scrub->pfss_ts_mod); 1511 pf_change_a(&opt[6], 1512 &th->th_sum, ts_value, 0); 1513 copyback = 1; 1514 } 1515 } 1516 /* FALLTHROUGH */ 1517 default: 1518 hlen -= MAX(opt[1], 2); 1519 opt += MAX(opt[1], 2); 1520 break; 1521 } 1522 } 1523 if (copyback) { 1524 /* Copyback the options, caller copys back header */ 1525 *writeback = 1; 1526 m_copyback(m, off + sizeof(struct tcphdr), 1527 (th->th_off << 2) - sizeof(struct tcphdr), hdr + 1528 sizeof(struct tcphdr)); 1529 } 1530 } 1531 1532 1533 /* I have a dream.... TCP segment reassembly.... */ 1534 return (0); 1535 } 1536 1537 int 1538 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th, 1539 int off) 1540 { 1541 u_int16_t *mss; 1542 int thoff; 1543 int opt, cnt, optlen = 0; 1544 int rewrite = 0; 1545 u_char *optp; 1546 1547 thoff = th->th_off << 2; 1548 cnt = thoff - sizeof(struct tcphdr); 1549 optp = mtod(m, caddr_t) + off + sizeof(struct tcphdr); 1550 1551 for (; cnt > 0; cnt -= optlen, optp += optlen) { 1552 opt = optp[0]; 1553 if (opt == TCPOPT_EOL) 1554 break; 1555 if (opt == TCPOPT_NOP) 1556 optlen = 1; 1557 else { 1558 if (cnt < 2) 1559 break; 1560 optlen = optp[1]; 1561 if (optlen < 2 || optlen > cnt) 1562 break; 1563 } 1564 switch (opt) { 1565 case TCPOPT_MAXSEG: 1566 mss = (u_int16_t *)(optp + 2); 1567 if ((ntohs(*mss)) > r->max_mss) { 1568 th->th_sum = pf_cksum_fixup(th->th_sum, 1569 *mss, htons(r->max_mss)); 1570 *mss = htons(r->max_mss); 1571 rewrite = 1; 1572 } 1573 break; 1574 default: 1575 break; 1576 } 1577 } 1578 1579 return (rewrite); 1580 } 1581