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 1.7 2006/12/22 23:44:57 swildner 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_cat(m, m2); 499 } 500 501 ip->ip_src = (*frag)->fr_src; 502 ip->ip_dst = (*frag)->fr_dst; 503 504 /* Remove from fragment queue */ 505 pf_remove_fragment(*frag); 506 *frag = NULL; 507 508 hlen = ip->ip_hl << 2; 509 ip->ip_len = off + hlen; 510 m->m_len += hlen; 511 m->m_data -= hlen; 512 513 /* some debugging cruft by sklower, below, will go away soon */ 514 /* XXX this should be done elsewhere */ 515 if (m->m_flags & M_PKTHDR) { 516 int plen = 0; 517 for (m2 = m; m2; m2 = m2->m_next) 518 plen += m2->m_len; 519 m->m_pkthdr.len = plen; 520 } 521 522 DPFPRINTF(("complete: %p(%d)\n", m, ip->ip_len)); 523 return (m); 524 525 drop_fragment: 526 /* Oops - fail safe - drop packet */ 527 pool_put(&pf_frent_pl, frent); 528 pf_nfrents--; 529 m_freem(m); 530 return (NULL); 531 } 532 533 struct mbuf * 534 pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff, 535 int drop, int *nomem) 536 { 537 struct mbuf *m = *m0; 538 struct pf_frcache *frp, *fra, *cur = NULL; 539 int ip_len = h->ip_len - (h->ip_hl << 2); 540 u_int16_t off = h->ip_off << 3; 541 u_int16_t max = ip_len + off; 542 int hosed = 0; 543 544 KASSERT((*frag == NULL || !BUFFER_FRAGMENTS(*frag)), 545 ("!(*frag == NULL || !BUFFER_FRAGMENTS(*frag)): %s", __func__)); 546 547 /* Create a new range queue for this packet */ 548 if (*frag == NULL) { 549 *frag = pool_get(&pf_cache_pl, PR_NOWAIT); 550 if (*frag == NULL) { 551 pf_flush_fragments(); 552 *frag = pool_get(&pf_cache_pl, PR_NOWAIT); 553 if (*frag == NULL) 554 goto no_mem; 555 } 556 557 /* Get an entry for the queue */ 558 cur = pool_get(&pf_cent_pl, PR_NOWAIT); 559 if (cur == NULL) { 560 pool_put(&pf_cache_pl, *frag); 561 *frag = NULL; 562 goto no_mem; 563 } 564 pf_ncache++; 565 566 (*frag)->fr_flags = PFFRAG_NOBUFFER; 567 (*frag)->fr_max = 0; 568 (*frag)->fr_src = h->ip_src; 569 (*frag)->fr_dst = h->ip_dst; 570 (*frag)->fr_p = h->ip_p; 571 (*frag)->fr_id = h->ip_id; 572 (*frag)->fr_timeout = time_second; 573 574 cur->fr_off = off; 575 cur->fr_end = max; 576 LIST_INIT(&(*frag)->fr_cache); 577 LIST_INSERT_HEAD(&(*frag)->fr_cache, cur, fr_next); 578 579 RB_INSERT(pf_frag_tree, &pf_cache_tree, *frag); 580 TAILQ_INSERT_HEAD(&pf_cachequeue, *frag, frag_next); 581 582 DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max)); 583 584 goto pass; 585 } 586 587 /* 588 * Find a fragment after the current one: 589 * - off contains the real shifted offset. 590 */ 591 frp = NULL; 592 LIST_FOREACH(fra, &(*frag)->fr_cache, fr_next) { 593 if (fra->fr_off > off) 594 break; 595 frp = fra; 596 } 597 598 KASSERT((frp != NULL || fra != NULL), 599 ("!(frp != NULL || fra != NULL): %s", __func__)); 600 601 if (frp != NULL) { 602 int precut; 603 604 precut = frp->fr_end - off; 605 if (precut >= ip_len) { 606 /* Fragment is entirely a duplicate */ 607 DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n", 608 h->ip_id, frp->fr_off, frp->fr_end, off, max)); 609 goto drop_fragment; 610 } 611 if (precut == 0) { 612 /* They are adjacent. Fixup cache entry */ 613 DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n", 614 h->ip_id, frp->fr_off, frp->fr_end, off, max)); 615 frp->fr_end = max; 616 } else if (precut > 0) { 617 /* The first part of this payload overlaps with a 618 * fragment that has already been passed. 619 * Need to trim off the first part of the payload. 620 * But to do so easily, we need to create another 621 * mbuf to throw the original header into. 622 */ 623 624 DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n", 625 h->ip_id, precut, frp->fr_off, frp->fr_end, off, 626 max)); 627 628 off += precut; 629 max -= precut; 630 /* Update the previous frag to encompass this one */ 631 frp->fr_end = max; 632 633 if (!drop) { 634 /* XXX Optimization opportunity 635 * This is a very heavy way to trim the payload. 636 * we could do it much faster by diddling mbuf 637 * internals but that would be even less legible 638 * than this mbuf magic. For my next trick, 639 * I'll pull a rabbit out of my laptop. 640 */ 641 *m0 = m_dup(m, MB_DONTWAIT); 642 /* From KAME Project : We have missed this! */ 643 m_adj(*m0, (h->ip_hl << 2) - 644 (*m0)->m_pkthdr.len); 645 if (*m0 == NULL) 646 goto no_mem; 647 KASSERT(((*m0)->m_next == NULL), 648 ("(*m0)->m_next != NULL: %s", 649 __func__)); 650 m_adj(m, precut + (h->ip_hl << 2)); 651 m_cat(*m0, m); 652 m = *m0; 653 if (m->m_flags & M_PKTHDR) { 654 int plen = 0; 655 struct mbuf *t; 656 for (t = m; t; t = t->m_next) 657 plen += t->m_len; 658 m->m_pkthdr.len = plen; 659 } 660 661 662 h = mtod(m, struct ip *); 663 664 KASSERT(((int)m->m_len == 665 h->ip_len - precut), 666 ("m->m_len != h->ip_len - precut: %s", 667 __func__)); 668 h->ip_off = h->ip_off + 669 (precut >> 3); 670 h->ip_len = h->ip_len - precut; 671 } else { 672 hosed++; 673 } 674 } else { 675 /* There is a gap between fragments */ 676 677 DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n", 678 h->ip_id, -precut, frp->fr_off, frp->fr_end, off, 679 max)); 680 681 cur = pool_get(&pf_cent_pl, PR_NOWAIT); 682 if (cur == NULL) 683 goto no_mem; 684 pf_ncache++; 685 686 cur->fr_off = off; 687 cur->fr_end = max; 688 LIST_INSERT_AFTER(frp, cur, fr_next); 689 } 690 } 691 692 if (fra != NULL) { 693 int aftercut; 694 int merge = 0; 695 696 aftercut = max - fra->fr_off; 697 if (aftercut == 0) { 698 /* Adjacent fragments */ 699 DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n", 700 h->ip_id, off, max, fra->fr_off, fra->fr_end)); 701 fra->fr_off = off; 702 merge = 1; 703 } else if (aftercut > 0) { 704 /* Need to chop off the tail of this fragment */ 705 DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n", 706 h->ip_id, aftercut, off, max, fra->fr_off, 707 fra->fr_end)); 708 fra->fr_off = off; 709 max -= aftercut; 710 711 merge = 1; 712 713 if (!drop) { 714 m_adj(m, -aftercut); 715 if (m->m_flags & M_PKTHDR) { 716 int plen = 0; 717 struct mbuf *t; 718 for (t = m; t; t = t->m_next) 719 plen += t->m_len; 720 m->m_pkthdr.len = plen; 721 } 722 h = mtod(m, struct ip *); 723 KASSERT(((int)m->m_len == h->ip_len - aftercut), 724 ("m->m_len != h->ip_len - aftercut: %s", 725 __func__)); 726 h->ip_len = h->ip_len - aftercut; 727 } else { 728 hosed++; 729 } 730 } else if (frp == NULL) { 731 /* There is a gap between fragments */ 732 DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n", 733 h->ip_id, -aftercut, off, max, fra->fr_off, 734 fra->fr_end)); 735 736 cur = pool_get(&pf_cent_pl, PR_NOWAIT); 737 if (cur == NULL) 738 goto no_mem; 739 pf_ncache++; 740 741 cur->fr_off = off; 742 cur->fr_end = max; 743 LIST_INSERT_BEFORE(fra, cur, fr_next); 744 } 745 746 747 /* Need to glue together two separate fragment descriptors */ 748 if (merge) { 749 if (cur && fra->fr_off <= cur->fr_end) { 750 /* Need to merge in a previous 'cur' */ 751 DPFPRINTF(("fragcache[%d]: adjacent(merge " 752 "%d-%d) %d-%d (%d-%d)\n", 753 h->ip_id, cur->fr_off, cur->fr_end, off, 754 max, fra->fr_off, fra->fr_end)); 755 fra->fr_off = cur->fr_off; 756 LIST_REMOVE(cur, fr_next); 757 pool_put(&pf_cent_pl, cur); 758 pf_ncache--; 759 cur = NULL; 760 761 } else if (frp && fra->fr_off <= frp->fr_end) { 762 /* Need to merge in a modified 'frp' */ 763 KASSERT((cur == NULL), ("cur != NULL: %s", 764 __func__)); 765 DPFPRINTF(("fragcache[%d]: adjacent(merge " 766 "%d-%d) %d-%d (%d-%d)\n", 767 h->ip_id, frp->fr_off, frp->fr_end, off, 768 max, fra->fr_off, fra->fr_end)); 769 fra->fr_off = frp->fr_off; 770 LIST_REMOVE(frp, fr_next); 771 pool_put(&pf_cent_pl, frp); 772 pf_ncache--; 773 frp = NULL; 774 775 } 776 } 777 } 778 779 if (hosed) { 780 /* 781 * We must keep tracking the overall fragment even when 782 * we're going to drop it anyway so that we know when to 783 * free the overall descriptor. Thus we drop the frag late. 784 */ 785 goto drop_fragment; 786 } 787 788 789 pass: 790 /* Update maximum data size */ 791 if ((*frag)->fr_max < max) 792 (*frag)->fr_max = max; 793 794 /* This is the last segment */ 795 if (!mff) 796 (*frag)->fr_flags |= PFFRAG_SEENLAST; 797 798 /* Check if we are completely reassembled */ 799 if (((*frag)->fr_flags & PFFRAG_SEENLAST) && 800 LIST_FIRST(&(*frag)->fr_cache)->fr_off == 0 && 801 LIST_FIRST(&(*frag)->fr_cache)->fr_end == (*frag)->fr_max) { 802 /* Remove from fragment queue */ 803 DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id, 804 (*frag)->fr_max)); 805 pf_free_fragment(*frag); 806 *frag = NULL; 807 } 808 809 return (m); 810 811 no_mem: 812 *nomem = 1; 813 814 /* Still need to pay attention to !IP_MF */ 815 if (!mff && *frag != NULL) 816 (*frag)->fr_flags |= PFFRAG_SEENLAST; 817 818 m_freem(m); 819 return (NULL); 820 821 drop_fragment: 822 823 /* Still need to pay attention to !IP_MF */ 824 if (!mff && *frag != NULL) 825 (*frag)->fr_flags |= PFFRAG_SEENLAST; 826 827 if (drop) { 828 /* This fragment has been deemed bad. Don't reass */ 829 if (((*frag)->fr_flags & PFFRAG_DROP) == 0) 830 DPFPRINTF(("fragcache[%d]: dropping overall fragment\n", 831 h->ip_id)); 832 (*frag)->fr_flags |= PFFRAG_DROP; 833 } 834 835 m_freem(m); 836 return (NULL); 837 } 838 839 int 840 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason) 841 { 842 struct mbuf *m = *m0; 843 struct pf_rule *r; 844 struct pf_frent *frent; 845 struct pf_fragment *frag = NULL; 846 struct ip *h = mtod(m, struct ip *); 847 int mff = (h->ip_off & IP_MF); 848 int hlen = h->ip_hl << 2; 849 u_int16_t fragoff = (h->ip_off & IP_OFFMASK) << 3; 850 u_int16_t max; 851 int ip_len; 852 int ip_off; 853 854 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 855 while (r != NULL) { 856 r->evaluations++; 857 if (r->kif != NULL && 858 (r->kif != kif && r->kif != kif->pfik_parent) == !r->ifnot) 859 r = r->skip[PF_SKIP_IFP].ptr; 860 else if (r->direction && r->direction != dir) 861 r = r->skip[PF_SKIP_DIR].ptr; 862 else if (r->af && r->af != AF_INET) 863 r = r->skip[PF_SKIP_AF].ptr; 864 else if (r->proto && r->proto != h->ip_p) 865 r = r->skip[PF_SKIP_PROTO].ptr; 866 else if (PF_MISMATCHAW(&r->src.addr, 867 (struct pf_addr *)&h->ip_src.s_addr, AF_INET, r->src.not)) 868 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 869 else if (PF_MISMATCHAW(&r->dst.addr, 870 (struct pf_addr *)&h->ip_dst.s_addr, AF_INET, r->dst.not)) 871 r = r->skip[PF_SKIP_DST_ADDR].ptr; 872 else 873 break; 874 } 875 876 if (r == NULL) 877 return (PF_PASS); 878 else 879 r->packets++; 880 881 /* Check for illegal packets */ 882 if (hlen < (int)sizeof(struct ip)) 883 goto drop; 884 885 if (hlen > h->ip_len) 886 goto drop; 887 888 /* Clear IP_DF if the rule uses the no-df option */ 889 if (r->rule_flag & PFRULE_NODF) 890 h->ip_off &= ~IP_DF; 891 892 /* We will need other tests here */ 893 if (!fragoff && !mff) 894 goto no_fragment; 895 896 /* We're dealing with a fragment now. Don't allow fragments 897 * with IP_DF to enter the cache. If the flag was cleared by 898 * no-df above, fine. Otherwise drop it. 899 */ 900 if (h->ip_off & IP_DF) { 901 DPFPRINTF(("IP_DF\n")); 902 goto bad; 903 } 904 905 ip_len = h->ip_len - hlen; 906 ip_off = (h->ip_off & IP_OFFMASK) << 3; 907 908 /* All fragments are 8 byte aligned */ 909 if (mff && (ip_len & 0x7)) { 910 DPFPRINTF(("mff and %d\n", ip_len)); 911 goto bad; 912 } 913 914 /* Respect maximum length */ 915 if (fragoff + ip_len > IP_MAXPACKET) { 916 DPFPRINTF(("max packet %d\n", fragoff + ip_len)); 917 goto bad; 918 } 919 max = fragoff + ip_len; 920 921 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) { 922 /* Fully buffer all of the fragments */ 923 924 frag = pf_find_fragment(h, &pf_frag_tree); 925 926 /* Check if we saw the last fragment already */ 927 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 928 max > frag->fr_max) 929 goto bad; 930 931 /* Get an entry for the fragment queue */ 932 frent = pool_get(&pf_frent_pl, PR_NOWAIT); 933 if (frent == NULL) { 934 REASON_SET(reason, PFRES_MEMORY); 935 return (PF_DROP); 936 } 937 pf_nfrents++; 938 frent->fr_ip = h; 939 frent->fr_m = m; 940 941 /* Might return a completely reassembled mbuf, or NULL */ 942 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max)); 943 *m0 = m = pf_reassemble(m0, &frag, frent, mff); 944 945 if (m == NULL) 946 return (PF_DROP); 947 948 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP)) 949 goto drop; 950 951 h = mtod(m, struct ip *); 952 } else { 953 /* non-buffering fragment cache (drops or masks overlaps) */ 954 int nomem = 0; 955 956 if (dir == PF_OUT) { 957 if (m->m_pkthdr.fw_flags & PF_MBUF_FRAGCACHE) { 958 /* Already passed the fragment cache in the 959 * input direction. If we continued, it would 960 * appear to be a dup and would be dropped. 961 */ 962 goto fragment_pass; 963 } 964 } 965 966 frag = pf_find_fragment(h, &pf_cache_tree); 967 968 /* Check if we saw the last fragment already */ 969 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 970 max > frag->fr_max) { 971 if (r->rule_flag & PFRULE_FRAGDROP) 972 frag->fr_flags |= PFFRAG_DROP; 973 goto bad; 974 } 975 976 *m0 = m = pf_fragcache(m0, h, &frag, mff, 977 (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem); 978 if (m == NULL) { 979 if (nomem) 980 goto no_mem; 981 goto drop; 982 } 983 984 if (dir == PF_IN) 985 m->m_pkthdr.fw_flags |= PF_MBUF_FRAGCACHE; 986 987 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP)) 988 goto drop; 989 goto fragment_pass; 990 } 991 992 no_fragment: 993 /* At this point, only IP_DF is allowed in ip_off */ 994 h->ip_off &= IP_DF; 995 996 /* Enforce a minimum ttl, may cause endless packet loops */ 997 if (r->min_ttl && h->ip_ttl < r->min_ttl) 998 h->ip_ttl = r->min_ttl; 999 1000 if (r->rule_flag & PFRULE_RANDOMID) { 1001 #ifdef RANDOM_IP_ID 1002 h->ip_id = ip_randomid(); 1003 #else 1004 h->ip_id = htons(ip_id++); 1005 #endif 1006 } 1007 1008 return (PF_PASS); 1009 1010 fragment_pass: 1011 /* Enforce a minimum ttl, may cause endless packet loops */ 1012 if (r->min_ttl && h->ip_ttl < r->min_ttl) 1013 h->ip_ttl = r->min_ttl; 1014 1015 return (PF_PASS); 1016 1017 no_mem: 1018 REASON_SET(reason, PFRES_MEMORY); 1019 if (r != NULL && r->log) 1020 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL); 1021 return (PF_DROP); 1022 1023 drop: 1024 REASON_SET(reason, PFRES_NORM); 1025 if (r != NULL && r->log) 1026 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL); 1027 return (PF_DROP); 1028 1029 bad: 1030 DPFPRINTF(("dropping bad fragment\n")); 1031 1032 /* Free associated fragments */ 1033 if (frag != NULL) 1034 pf_free_fragment(frag); 1035 1036 REASON_SET(reason, PFRES_FRAG); 1037 if (r != NULL && r->log) 1038 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL); 1039 1040 return (PF_DROP); 1041 } 1042 1043 #ifdef INET6 1044 int 1045 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif, 1046 u_short *reason) 1047 { 1048 struct mbuf *m = *m0; 1049 struct pf_rule *r; 1050 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1051 int off; 1052 struct ip6_ext ext; 1053 struct ip6_opt opt; 1054 struct ip6_opt_jumbo jumbo; 1055 struct ip6_frag frag; 1056 u_int32_t jumbolen = 0, plen; 1057 u_int16_t fragoff = 0; 1058 int optend; 1059 int ooff; 1060 u_int8_t proto; 1061 int terminal; 1062 1063 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1064 while (r != NULL) { 1065 r->evaluations++; 1066 if (r->kif != NULL && 1067 (r->kif != kif && r->kif != kif->pfik_parent) == !r->ifnot) 1068 r = r->skip[PF_SKIP_IFP].ptr; 1069 else if (r->direction && r->direction != dir) 1070 r = r->skip[PF_SKIP_DIR].ptr; 1071 else if (r->af && r->af != AF_INET6) 1072 r = r->skip[PF_SKIP_AF].ptr; 1073 #if 0 /* header chain! */ 1074 else if (r->proto && r->proto != h->ip6_nxt) 1075 r = r->skip[PF_SKIP_PROTO].ptr; 1076 #endif 1077 else if (PF_MISMATCHAW(&r->src.addr, 1078 (struct pf_addr *)&h->ip6_src, AF_INET6, r->src.not)) 1079 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1080 else if (PF_MISMATCHAW(&r->dst.addr, 1081 (struct pf_addr *)&h->ip6_dst, AF_INET6, r->dst.not)) 1082 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1083 else 1084 break; 1085 } 1086 1087 if (r == NULL) 1088 return (PF_PASS); 1089 else 1090 r->packets++; 1091 1092 /* Check for illegal packets */ 1093 if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len) 1094 goto drop; 1095 1096 off = sizeof(struct ip6_hdr); 1097 proto = h->ip6_nxt; 1098 terminal = 0; 1099 do { 1100 switch (proto) { 1101 case IPPROTO_FRAGMENT: 1102 goto fragment; 1103 break; 1104 case IPPROTO_AH: 1105 case IPPROTO_ROUTING: 1106 case IPPROTO_DSTOPTS: 1107 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1108 NULL, AF_INET6)) 1109 goto shortpkt; 1110 if (proto == IPPROTO_AH) 1111 off += (ext.ip6e_len + 2) * 4; 1112 else 1113 off += (ext.ip6e_len + 1) * 8; 1114 proto = ext.ip6e_nxt; 1115 break; 1116 case IPPROTO_HOPOPTS: 1117 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1118 NULL, AF_INET6)) 1119 goto shortpkt; 1120 optend = off + (ext.ip6e_len + 1) * 8; 1121 ooff = off + sizeof(ext); 1122 do { 1123 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type, 1124 sizeof(opt.ip6o_type), NULL, NULL, 1125 AF_INET6)) 1126 goto shortpkt; 1127 if (opt.ip6o_type == IP6OPT_PAD1) { 1128 ooff++; 1129 continue; 1130 } 1131 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt), 1132 NULL, NULL, AF_INET6)) 1133 goto shortpkt; 1134 if (ooff + sizeof(opt) + opt.ip6o_len > optend) 1135 goto drop; 1136 switch (opt.ip6o_type) { 1137 case IP6OPT_JUMBO: 1138 if (h->ip6_plen != 0) 1139 goto drop; 1140 if (!pf_pull_hdr(m, ooff, &jumbo, 1141 sizeof(jumbo), NULL, NULL, 1142 AF_INET6)) 1143 goto shortpkt; 1144 memcpy(&jumbolen, jumbo.ip6oj_jumbo_len, 1145 sizeof(jumbolen)); 1146 jumbolen = ntohl(jumbolen); 1147 if (jumbolen <= IPV6_MAXPACKET) 1148 goto drop; 1149 if (sizeof(struct ip6_hdr) + jumbolen != 1150 m->m_pkthdr.len) 1151 goto drop; 1152 break; 1153 default: 1154 break; 1155 } 1156 ooff += sizeof(opt) + opt.ip6o_len; 1157 } while (ooff < optend); 1158 1159 off = optend; 1160 proto = ext.ip6e_nxt; 1161 break; 1162 default: 1163 terminal = 1; 1164 break; 1165 } 1166 } while (!terminal); 1167 1168 /* jumbo payload option must be present, or plen > 0 */ 1169 if (ntohs(h->ip6_plen) == 0) 1170 plen = jumbolen; 1171 else 1172 plen = ntohs(h->ip6_plen); 1173 if (plen == 0) 1174 goto drop; 1175 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1176 goto shortpkt; 1177 1178 /* Enforce a minimum ttl, may cause endless packet loops */ 1179 if (r->min_ttl && h->ip6_hlim < r->min_ttl) 1180 h->ip6_hlim = r->min_ttl; 1181 1182 return (PF_PASS); 1183 1184 fragment: 1185 if (ntohs(h->ip6_plen) == 0 || jumbolen) 1186 goto drop; 1187 plen = ntohs(h->ip6_plen); 1188 1189 if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6)) 1190 goto shortpkt; 1191 fragoff = ntohs(frag.ip6f_offlg & IP6F_OFF_MASK); 1192 if (fragoff + (plen - off - sizeof(frag)) > IPV6_MAXPACKET) 1193 goto badfrag; 1194 1195 /* do something about it */ 1196 return (PF_PASS); 1197 1198 shortpkt: 1199 REASON_SET(reason, PFRES_SHORT); 1200 if (r != NULL && r->log) 1201 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL); 1202 return (PF_DROP); 1203 1204 drop: 1205 REASON_SET(reason, PFRES_NORM); 1206 if (r != NULL && r->log) 1207 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL); 1208 return (PF_DROP); 1209 1210 badfrag: 1211 REASON_SET(reason, PFRES_FRAG); 1212 if (r != NULL && r->log) 1213 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL); 1214 return (PF_DROP); 1215 } 1216 #endif 1217 1218 int 1219 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff, 1220 int off, void *h, struct pf_pdesc *pd) 1221 { 1222 struct pf_rule *r, *rm = NULL; 1223 struct tcphdr *th = pd->hdr.tcp; 1224 int rewrite = 0; 1225 u_short reason; 1226 u_int8_t flags; 1227 sa_family_t af = pd->af; 1228 1229 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1230 while (r != NULL) { 1231 r->evaluations++; 1232 if (r->kif != NULL && 1233 (r->kif != kif && r->kif != kif->pfik_parent) == !r->ifnot) 1234 r = r->skip[PF_SKIP_IFP].ptr; 1235 else if (r->direction && r->direction != dir) 1236 r = r->skip[PF_SKIP_DIR].ptr; 1237 else if (r->af && r->af != af) 1238 r = r->skip[PF_SKIP_AF].ptr; 1239 else if (r->proto && r->proto != pd->proto) 1240 r = r->skip[PF_SKIP_PROTO].ptr; 1241 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, r->src.not)) 1242 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1243 else if (r->src.port_op && !pf_match_port(r->src.port_op, 1244 r->src.port[0], r->src.port[1], th->th_sport)) 1245 r = r->skip[PF_SKIP_SRC_PORT].ptr; 1246 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, r->dst.not)) 1247 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1248 else if (r->dst.port_op && !pf_match_port(r->dst.port_op, 1249 r->dst.port[0], r->dst.port[1], th->th_dport)) 1250 r = r->skip[PF_SKIP_DST_PORT].ptr; 1251 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match( 1252 pf_osfp_fingerprint(pd, m, off, th), 1253 r->os_fingerprint)) 1254 r = TAILQ_NEXT(r, entries); 1255 else { 1256 rm = r; 1257 break; 1258 } 1259 } 1260 1261 if (rm == NULL) 1262 return (PF_PASS); 1263 else 1264 r->packets++; 1265 1266 if (rm->rule_flag & PFRULE_REASSEMBLE_TCP) 1267 pd->flags |= PFDESC_TCP_NORM; 1268 1269 flags = th->th_flags; 1270 if (flags & TH_SYN) { 1271 /* Illegal packet */ 1272 if (flags & TH_RST) 1273 goto tcp_drop; 1274 1275 if (flags & TH_FIN) 1276 flags &= ~TH_FIN; 1277 } else { 1278 /* Illegal packet */ 1279 if (!(flags & (TH_ACK|TH_RST))) 1280 goto tcp_drop; 1281 } 1282 1283 if (!(flags & TH_ACK)) { 1284 /* These flags are only valid if ACK is set */ 1285 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG)) 1286 goto tcp_drop; 1287 } 1288 1289 /* Check for illegal header length */ 1290 if (th->th_off < (sizeof(struct tcphdr) >> 2)) 1291 goto tcp_drop; 1292 1293 /* If flags changed, or reserved data set, then adjust */ 1294 if (flags != th->th_flags || th->th_x2 != 0) { 1295 u_int16_t ov, nv; 1296 1297 ov = *(u_int16_t *)(&th->th_ack + 1); 1298 th->th_flags = flags; 1299 th->th_x2 = 0; 1300 nv = *(u_int16_t *)(&th->th_ack + 1); 1301 1302 th->th_sum = pf_cksum_fixup(th->th_sum, ov, nv); 1303 rewrite = 1; 1304 } 1305 1306 /* Remove urgent pointer, if TH_URG is not set */ 1307 if (!(flags & TH_URG) && th->th_urp) { 1308 th->th_sum = pf_cksum_fixup(th->th_sum, th->th_urp, 0); 1309 th->th_urp = 0; 1310 rewrite = 1; 1311 } 1312 1313 /* Process options */ 1314 if (r->max_mss && pf_normalize_tcpopt(r, m, th, off)) 1315 rewrite = 1; 1316 1317 /* copy back packet headers if we sanitized */ 1318 if (rewrite) 1319 m_copyback(m, off, sizeof(*th), (caddr_t)th); 1320 1321 return (PF_PASS); 1322 1323 tcp_drop: 1324 REASON_SET(&reason, PFRES_NORM); 1325 if (rm != NULL && r->log) 1326 PFLOG_PACKET(kif, h, m, AF_INET, dir, reason, r, NULL, NULL); 1327 return (PF_DROP); 1328 } 1329 1330 int 1331 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd, 1332 struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst) 1333 { 1334 u_int8_t hdr[60]; 1335 u_int8_t *opt; 1336 1337 KASSERT((src->scrub == NULL), 1338 ("pf_normalize_tcp_init: src->scrub != NULL")); 1339 1340 src->scrub = pool_get(&pf_state_scrub_pl, PR_NOWAIT); 1341 if (src->scrub == NULL) 1342 return (1); 1343 bzero(src->scrub, sizeof(*src->scrub)); 1344 1345 switch (pd->af) { 1346 #ifdef INET 1347 case AF_INET: { 1348 struct ip *h = mtod(m, struct ip *); 1349 src->scrub->pfss_ttl = h->ip_ttl; 1350 break; 1351 } 1352 #endif /* INET */ 1353 #ifdef INET6 1354 case AF_INET6: { 1355 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1356 src->scrub->pfss_ttl = h->ip6_hlim; 1357 break; 1358 } 1359 #endif /* INET6 */ 1360 } 1361 1362 1363 /* 1364 * All normalizations below are only begun if we see the start of 1365 * the connections. They must all set an enabled bit in pfss_flags 1366 */ 1367 if ((th->th_flags & TH_SYN) == 0) 1368 return (0); 1369 1370 1371 if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub && 1372 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1373 /* Diddle with TCP options */ 1374 int hlen; 1375 opt = hdr + sizeof(struct tcphdr); 1376 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1377 while (hlen >= TCPOLEN_TIMESTAMP) { 1378 switch (*opt) { 1379 case TCPOPT_EOL: /* FALLTHROUGH */ 1380 case TCPOPT_NOP: 1381 opt++; 1382 hlen--; 1383 break; 1384 case TCPOPT_TIMESTAMP: 1385 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1386 src->scrub->pfss_flags |= 1387 PFSS_TIMESTAMP; 1388 src->scrub->pfss_ts_mod = karc4random(); 1389 } 1390 /* FALLTHROUGH */ 1391 default: 1392 hlen -= MAX(opt[1], 2); 1393 opt += MAX(opt[1], 2); 1394 break; 1395 } 1396 } 1397 } 1398 1399 return (0); 1400 } 1401 1402 void 1403 pf_normalize_tcp_cleanup(struct pf_state *state) 1404 { 1405 if (state->src.scrub) 1406 pool_put(&pf_state_scrub_pl, state->src.scrub); 1407 if (state->dst.scrub) 1408 pool_put(&pf_state_scrub_pl, state->dst.scrub); 1409 1410 /* Someday... flush the TCP segment reassembly descriptors. */ 1411 } 1412 1413 int 1414 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd, 1415 u_short *reason, struct tcphdr *th, struct pf_state_peer *src, 1416 struct pf_state_peer *dst, int *writeback) 1417 { 1418 u_int8_t hdr[60]; 1419 u_int8_t *opt; 1420 int copyback = 0; 1421 1422 KASSERT((src->scrub || dst->scrub), 1423 ("pf_normalize_tcp_statefull: src->scrub && dst->scrub!")); 1424 1425 /* 1426 * Enforce the minimum TTL seen for this connection. Negate a common 1427 * technique to evade an intrusion detection system and confuse 1428 * firewall state code. 1429 */ 1430 switch (pd->af) { 1431 #ifdef INET 1432 case AF_INET: { 1433 if (src->scrub) { 1434 struct ip *h = mtod(m, struct ip *); 1435 if (h->ip_ttl > src->scrub->pfss_ttl) 1436 src->scrub->pfss_ttl = h->ip_ttl; 1437 h->ip_ttl = src->scrub->pfss_ttl; 1438 } 1439 break; 1440 } 1441 #endif /* INET */ 1442 #ifdef INET6 1443 case AF_INET6: { 1444 if (src->scrub) { 1445 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1446 if (h->ip6_hlim > src->scrub->pfss_ttl) 1447 src->scrub->pfss_ttl = h->ip6_hlim; 1448 h->ip6_hlim = src->scrub->pfss_ttl; 1449 } 1450 break; 1451 } 1452 #endif /* INET6 */ 1453 } 1454 1455 if (th->th_off > (sizeof(struct tcphdr) >> 2) && 1456 ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) || 1457 (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) && 1458 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1459 /* Diddle with TCP options */ 1460 int hlen; 1461 opt = hdr + sizeof(struct tcphdr); 1462 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1463 while (hlen >= TCPOLEN_TIMESTAMP) { 1464 switch (*opt) { 1465 case TCPOPT_EOL: /* FALLTHROUGH */ 1466 case TCPOPT_NOP: 1467 opt++; 1468 hlen--; 1469 break; 1470 case TCPOPT_TIMESTAMP: 1471 /* Modulate the timestamps. Can be used for 1472 * NAT detection, OS uptime determination or 1473 * reboot detection. 1474 */ 1475 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1476 u_int32_t ts_value; 1477 if (src->scrub && 1478 (src->scrub->pfss_flags & 1479 PFSS_TIMESTAMP)) { 1480 memcpy(&ts_value, &opt[2], 1481 sizeof(u_int32_t)); 1482 ts_value = htonl(ntohl(ts_value) 1483 + src->scrub->pfss_ts_mod); 1484 pf_change_a(&opt[2], 1485 &th->th_sum, ts_value, 0); 1486 copyback = 1; 1487 } 1488 1489 /* Modulate TS reply iff valid (!0) */ 1490 memcpy(&ts_value, &opt[6], 1491 sizeof(u_int32_t)); 1492 if (ts_value && dst->scrub && 1493 (dst->scrub->pfss_flags & 1494 PFSS_TIMESTAMP)) { 1495 ts_value = htonl(ntohl(ts_value) 1496 - dst->scrub->pfss_ts_mod); 1497 pf_change_a(&opt[6], 1498 &th->th_sum, ts_value, 0); 1499 copyback = 1; 1500 } 1501 } 1502 /* FALLTHROUGH */ 1503 default: 1504 hlen -= MAX(opt[1], 2); 1505 opt += MAX(opt[1], 2); 1506 break; 1507 } 1508 } 1509 if (copyback) { 1510 /* Copyback the options, caller copys back header */ 1511 *writeback = 1; 1512 m_copyback(m, off + sizeof(struct tcphdr), 1513 (th->th_off << 2) - sizeof(struct tcphdr), hdr + 1514 sizeof(struct tcphdr)); 1515 } 1516 } 1517 1518 1519 /* I have a dream.... TCP segment reassembly.... */ 1520 return (0); 1521 } 1522 1523 int 1524 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th, 1525 int off) 1526 { 1527 u_int16_t *mss; 1528 int thoff; 1529 int opt, cnt, optlen = 0; 1530 int rewrite = 0; 1531 u_char *optp; 1532 1533 thoff = th->th_off << 2; 1534 cnt = thoff - sizeof(struct tcphdr); 1535 optp = mtod(m, caddr_t) + off + sizeof(struct tcphdr); 1536 1537 for (; cnt > 0; cnt -= optlen, optp += optlen) { 1538 opt = optp[0]; 1539 if (opt == TCPOPT_EOL) 1540 break; 1541 if (opt == TCPOPT_NOP) 1542 optlen = 1; 1543 else { 1544 if (cnt < 2) 1545 break; 1546 optlen = optp[1]; 1547 if (optlen < 2 || optlen > cnt) 1548 break; 1549 } 1550 switch (opt) { 1551 case TCPOPT_MAXSEG: 1552 mss = (u_int16_t *)(optp + 2); 1553 if ((ntohs(*mss)) > r->max_mss) { 1554 th->th_sum = pf_cksum_fixup(th->th_sum, 1555 *mss, htons(r->max_mss)); 1556 *mss = htons(r->max_mss); 1557 rewrite = 1; 1558 } 1559 break; 1560 default: 1561 break; 1562 } 1563 } 1564 1565 return (rewrite); 1566 } 1567