1 /* $OpenBSD: pf_norm.c,v 1.113 2008/05/07 07:07:29 markus Exp $ */ 2 3 /* 4 * Copyright 2001 Niels Provos <provos@citi.umich.edu> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include "pflog.h" 29 30 #include <sys/param.h> 31 #include <sys/systm.h> 32 #include <sys/mbuf.h> 33 #include <sys/filio.h> 34 #include <sys/fcntl.h> 35 #include <sys/socket.h> 36 #include <sys/kernel.h> 37 #include <sys/time.h> 38 #include <sys/pool.h> 39 40 #include <dev/rndvar.h> 41 #include <net/if.h> 42 #include <net/if_types.h> 43 #include <net/bpf.h> 44 #include <net/route.h> 45 #include <net/if_pflog.h> 46 47 #include <netinet/in.h> 48 #include <netinet/in_var.h> 49 #include <netinet/in_systm.h> 50 #include <netinet/ip.h> 51 #include <netinet/ip_var.h> 52 #include <netinet/tcp.h> 53 #include <netinet/tcp_seq.h> 54 #include <netinet/udp.h> 55 #include <netinet/ip_icmp.h> 56 57 #ifdef INET6 58 #include <netinet/ip6.h> 59 #endif /* INET6 */ 60 61 #include <net/pfvar.h> 62 63 struct pf_frent { 64 LIST_ENTRY(pf_frent) fr_next; 65 struct ip *fr_ip; 66 struct mbuf *fr_m; 67 }; 68 69 struct pf_frcache { 70 LIST_ENTRY(pf_frcache) fr_next; 71 uint16_t fr_off; 72 uint16_t fr_end; 73 }; 74 75 #define PFFRAG_SEENLAST 0x0001 /* Seen the last fragment for this */ 76 #define PFFRAG_NOBUFFER 0x0002 /* Non-buffering fragment cache */ 77 #define PFFRAG_DROP 0x0004 /* Drop all fragments */ 78 #define BUFFER_FRAGMENTS(fr) (!((fr)->fr_flags & PFFRAG_NOBUFFER)) 79 80 struct pf_fragment { 81 RB_ENTRY(pf_fragment) fr_entry; 82 TAILQ_ENTRY(pf_fragment) frag_next; 83 struct in_addr fr_src; 84 struct in_addr fr_dst; 85 u_int8_t fr_p; /* protocol of this fragment */ 86 u_int8_t fr_flags; /* status flags */ 87 u_int16_t fr_id; /* fragment id for reassemble */ 88 u_int16_t fr_max; /* fragment data max */ 89 u_int32_t fr_timeout; 90 #define fr_queue fr_u.fru_queue 91 #define fr_cache fr_u.fru_cache 92 union { 93 LIST_HEAD(pf_fragq, pf_frent) fru_queue; /* buffering */ 94 LIST_HEAD(pf_cacheq, pf_frcache) fru_cache; /* non-buf */ 95 } fr_u; 96 }; 97 98 TAILQ_HEAD(pf_fragqueue, pf_fragment) pf_fragqueue; 99 TAILQ_HEAD(pf_cachequeue, pf_fragment) pf_cachequeue; 100 101 static __inline int pf_frag_compare(struct pf_fragment *, 102 struct pf_fragment *); 103 RB_HEAD(pf_frag_tree, pf_fragment) pf_frag_tree, pf_cache_tree; 104 RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 105 RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 106 107 /* Private prototypes */ 108 void pf_ip2key(struct pf_fragment *, struct ip *); 109 void pf_remove_fragment(struct pf_fragment *); 110 void pf_flush_fragments(void); 111 void pf_free_fragment(struct pf_fragment *); 112 struct pf_fragment *pf_find_fragment(struct ip *, struct pf_frag_tree *); 113 struct mbuf *pf_reassemble(struct mbuf **, struct pf_fragment **, 114 struct pf_frent *, int); 115 struct mbuf *pf_fragcache(struct mbuf **, struct ip*, 116 struct pf_fragment **, int, int, int *); 117 int pf_normalize_tcpopt(struct pf_rule *, struct mbuf *, 118 struct tcphdr *, int, sa_family_t); 119 120 #define DPFPRINTF(x) do { \ 121 if (pf_status.debug >= PF_DEBUG_MISC) { \ 122 printf("%s: ", __func__); \ 123 printf x ; \ 124 } \ 125 } while(0) 126 127 /* Globals */ 128 struct pool pf_frent_pl, pf_frag_pl, pf_cache_pl, pf_cent_pl; 129 struct pool pf_state_scrub_pl; 130 int pf_nfrents, pf_ncache; 131 132 void 133 pf_normalize_init(void) 134 { 135 pool_init(&pf_frent_pl, sizeof(struct pf_frent), 0, 0, 0, "pffrent", 136 NULL); 137 pool_init(&pf_frag_pl, sizeof(struct pf_fragment), 0, 0, 0, "pffrag", 138 NULL); 139 pool_init(&pf_cache_pl, sizeof(struct pf_fragment), 0, 0, 0, 140 "pffrcache", NULL); 141 pool_init(&pf_cent_pl, sizeof(struct pf_frcache), 0, 0, 0, "pffrcent", 142 NULL); 143 pool_init(&pf_state_scrub_pl, sizeof(struct pf_state_scrub), 0, 0, 0, 144 "pfstscr", NULL); 145 146 pool_sethiwat(&pf_frag_pl, PFFRAG_FRAG_HIWAT); 147 pool_sethardlimit(&pf_frent_pl, PFFRAG_FRENT_HIWAT, NULL, 0); 148 pool_sethardlimit(&pf_cache_pl, PFFRAG_FRCACHE_HIWAT, NULL, 0); 149 pool_sethardlimit(&pf_cent_pl, PFFRAG_FRCENT_HIWAT, NULL, 0); 150 151 TAILQ_INIT(&pf_fragqueue); 152 TAILQ_INIT(&pf_cachequeue); 153 } 154 155 static __inline int 156 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b) 157 { 158 int diff; 159 160 if ((diff = a->fr_id - b->fr_id)) 161 return (diff); 162 else if ((diff = a->fr_p - b->fr_p)) 163 return (diff); 164 else if (a->fr_src.s_addr < b->fr_src.s_addr) 165 return (-1); 166 else if (a->fr_src.s_addr > b->fr_src.s_addr) 167 return (1); 168 else if (a->fr_dst.s_addr < b->fr_dst.s_addr) 169 return (-1); 170 else if (a->fr_dst.s_addr > b->fr_dst.s_addr) 171 return (1); 172 return (0); 173 } 174 175 void 176 pf_purge_expired_fragments(void) 177 { 178 struct pf_fragment *frag; 179 u_int32_t expire = time_second - 180 pf_default_rule.timeout[PFTM_FRAG]; 181 182 while ((frag = TAILQ_LAST(&pf_fragqueue, pf_fragqueue)) != NULL) { 183 KASSERT(BUFFER_FRAGMENTS(frag)); 184 if (frag->fr_timeout > expire) 185 break; 186 187 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); 188 pf_free_fragment(frag); 189 } 190 191 while ((frag = TAILQ_LAST(&pf_cachequeue, pf_cachequeue)) != NULL) { 192 KASSERT(!BUFFER_FRAGMENTS(frag)); 193 if (frag->fr_timeout > expire) 194 break; 195 196 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); 197 pf_free_fragment(frag); 198 KASSERT(TAILQ_EMPTY(&pf_cachequeue) || 199 TAILQ_LAST(&pf_cachequeue, pf_cachequeue) != frag); 200 } 201 } 202 203 /* 204 * Try to flush old fragments to make space for new ones 205 */ 206 207 void 208 pf_flush_fragments(void) 209 { 210 struct pf_fragment *frag; 211 int goal; 212 213 goal = pf_nfrents * 9 / 10; 214 DPFPRINTF(("trying to free > %d frents\n", 215 pf_nfrents - goal)); 216 while (goal < pf_nfrents) { 217 frag = TAILQ_LAST(&pf_fragqueue, pf_fragqueue); 218 if (frag == NULL) 219 break; 220 pf_free_fragment(frag); 221 } 222 223 224 goal = pf_ncache * 9 / 10; 225 DPFPRINTF(("trying to free > %d cache entries\n", 226 pf_ncache - goal)); 227 while (goal < pf_ncache) { 228 frag = TAILQ_LAST(&pf_cachequeue, pf_cachequeue); 229 if (frag == NULL) 230 break; 231 pf_free_fragment(frag); 232 } 233 } 234 235 /* Frees the fragments and all associated entries */ 236 237 void 238 pf_free_fragment(struct pf_fragment *frag) 239 { 240 struct pf_frent *frent; 241 struct pf_frcache *frcache; 242 243 /* Free all fragments */ 244 if (BUFFER_FRAGMENTS(frag)) { 245 for (frent = LIST_FIRST(&frag->fr_queue); frent; 246 frent = LIST_FIRST(&frag->fr_queue)) { 247 LIST_REMOVE(frent, fr_next); 248 249 m_freem(frent->fr_m); 250 pool_put(&pf_frent_pl, frent); 251 pf_nfrents--; 252 } 253 } else { 254 for (frcache = LIST_FIRST(&frag->fr_cache); frcache; 255 frcache = LIST_FIRST(&frag->fr_cache)) { 256 LIST_REMOVE(frcache, fr_next); 257 258 KASSERT(LIST_EMPTY(&frag->fr_cache) || 259 LIST_FIRST(&frag->fr_cache)->fr_off > 260 frcache->fr_end); 261 262 pool_put(&pf_cent_pl, frcache); 263 pf_ncache--; 264 } 265 } 266 267 pf_remove_fragment(frag); 268 } 269 270 void 271 pf_ip2key(struct pf_fragment *key, struct ip *ip) 272 { 273 key->fr_p = ip->ip_p; 274 key->fr_id = ip->ip_id; 275 key->fr_src.s_addr = ip->ip_src.s_addr; 276 key->fr_dst.s_addr = ip->ip_dst.s_addr; 277 } 278 279 struct pf_fragment * 280 pf_find_fragment(struct ip *ip, struct pf_frag_tree *tree) 281 { 282 struct pf_fragment key; 283 struct pf_fragment *frag; 284 285 pf_ip2key(&key, ip); 286 287 frag = RB_FIND(pf_frag_tree, tree, &key); 288 if (frag != NULL) { 289 /* XXX Are we sure we want to update the timeout? */ 290 frag->fr_timeout = time_second; 291 if (BUFFER_FRAGMENTS(frag)) { 292 TAILQ_REMOVE(&pf_fragqueue, frag, frag_next); 293 TAILQ_INSERT_HEAD(&pf_fragqueue, frag, frag_next); 294 } else { 295 TAILQ_REMOVE(&pf_cachequeue, frag, frag_next); 296 TAILQ_INSERT_HEAD(&pf_cachequeue, frag, frag_next); 297 } 298 } 299 300 return (frag); 301 } 302 303 /* Removes a fragment from the fragment queue and frees the fragment */ 304 305 void 306 pf_remove_fragment(struct pf_fragment *frag) 307 { 308 if (BUFFER_FRAGMENTS(frag)) { 309 RB_REMOVE(pf_frag_tree, &pf_frag_tree, frag); 310 TAILQ_REMOVE(&pf_fragqueue, frag, frag_next); 311 pool_put(&pf_frag_pl, frag); 312 } else { 313 RB_REMOVE(pf_frag_tree, &pf_cache_tree, frag); 314 TAILQ_REMOVE(&pf_cachequeue, frag, frag_next); 315 pool_put(&pf_cache_pl, frag); 316 } 317 } 318 319 #define FR_IP_OFF(fr) ((ntohs((fr)->fr_ip->ip_off) & IP_OFFMASK) << 3) 320 struct mbuf * 321 pf_reassemble(struct mbuf **m0, struct pf_fragment **frag, 322 struct pf_frent *frent, int mff) 323 { 324 struct mbuf *m = *m0, *m2; 325 struct pf_frent *frea, *next; 326 struct pf_frent *frep = NULL; 327 struct ip *ip = frent->fr_ip; 328 int hlen = ip->ip_hl << 2; 329 u_int16_t off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3; 330 u_int16_t ip_len = ntohs(ip->ip_len) - ip->ip_hl * 4; 331 u_int16_t max = ip_len + off; 332 333 KASSERT(*frag == NULL || BUFFER_FRAGMENTS(*frag)); 334 335 /* Strip off ip header */ 336 m->m_data += hlen; 337 m->m_len -= hlen; 338 339 /* Create a new reassembly queue for this packet */ 340 if (*frag == NULL) { 341 *frag = pool_get(&pf_frag_pl, PR_NOWAIT); 342 if (*frag == NULL) { 343 pf_flush_fragments(); 344 *frag = pool_get(&pf_frag_pl, PR_NOWAIT); 345 if (*frag == NULL) 346 goto drop_fragment; 347 } 348 349 (*frag)->fr_flags = 0; 350 (*frag)->fr_max = 0; 351 (*frag)->fr_src = frent->fr_ip->ip_src; 352 (*frag)->fr_dst = frent->fr_ip->ip_dst; 353 (*frag)->fr_p = frent->fr_ip->ip_p; 354 (*frag)->fr_id = frent->fr_ip->ip_id; 355 (*frag)->fr_timeout = time_second; 356 LIST_INIT(&(*frag)->fr_queue); 357 358 RB_INSERT(pf_frag_tree, &pf_frag_tree, *frag); 359 TAILQ_INSERT_HEAD(&pf_fragqueue, *frag, frag_next); 360 361 /* We do not have a previous fragment */ 362 frep = NULL; 363 goto insert; 364 } 365 366 /* 367 * Find a fragment after the current one: 368 * - off contains the real shifted offset. 369 */ 370 LIST_FOREACH(frea, &(*frag)->fr_queue, fr_next) { 371 if (FR_IP_OFF(frea) > off) 372 break; 373 frep = frea; 374 } 375 376 KASSERT(frep != NULL || frea != NULL); 377 378 if (frep != NULL && 379 FR_IP_OFF(frep) + ntohs(frep->fr_ip->ip_len) - frep->fr_ip->ip_hl * 380 4 > off) 381 { 382 u_int16_t precut; 383 384 precut = FR_IP_OFF(frep) + ntohs(frep->fr_ip->ip_len) - 385 frep->fr_ip->ip_hl * 4 - off; 386 if (precut >= ip_len) 387 goto drop_fragment; 388 m_adj(frent->fr_m, precut); 389 DPFPRINTF(("overlap -%d\n", precut)); 390 /* Enforce 8 byte boundaries */ 391 ip->ip_off = htons(ntohs(ip->ip_off) + (precut >> 3)); 392 off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3; 393 ip_len -= precut; 394 ip->ip_len = htons(ip_len); 395 } 396 397 for (; frea != NULL && ip_len + off > FR_IP_OFF(frea); 398 frea = next) 399 { 400 u_int16_t aftercut; 401 402 aftercut = ip_len + off - FR_IP_OFF(frea); 403 DPFPRINTF(("adjust overlap %d\n", aftercut)); 404 if (aftercut < ntohs(frea->fr_ip->ip_len) - frea->fr_ip->ip_hl 405 * 4) 406 { 407 frea->fr_ip->ip_len = 408 htons(ntohs(frea->fr_ip->ip_len) - aftercut); 409 frea->fr_ip->ip_off = htons(ntohs(frea->fr_ip->ip_off) + 410 (aftercut >> 3)); 411 m_adj(frea->fr_m, aftercut); 412 break; 413 } 414 415 /* This fragment is completely overlapped, lose it */ 416 next = LIST_NEXT(frea, fr_next); 417 m_freem(frea->fr_m); 418 LIST_REMOVE(frea, fr_next); 419 pool_put(&pf_frent_pl, frea); 420 pf_nfrents--; 421 } 422 423 insert: 424 /* Update maximum data size */ 425 if ((*frag)->fr_max < max) 426 (*frag)->fr_max = max; 427 /* This is the last segment */ 428 if (!mff) 429 (*frag)->fr_flags |= PFFRAG_SEENLAST; 430 431 if (frep == NULL) 432 LIST_INSERT_HEAD(&(*frag)->fr_queue, frent, fr_next); 433 else 434 LIST_INSERT_AFTER(frep, frent, fr_next); 435 436 /* Check if we are completely reassembled */ 437 if (!((*frag)->fr_flags & PFFRAG_SEENLAST)) 438 return (NULL); 439 440 /* Check if we have all the data */ 441 off = 0; 442 for (frep = LIST_FIRST(&(*frag)->fr_queue); frep; frep = next) { 443 next = LIST_NEXT(frep, fr_next); 444 445 off += ntohs(frep->fr_ip->ip_len) - frep->fr_ip->ip_hl * 4; 446 if (off < (*frag)->fr_max && 447 (next == NULL || FR_IP_OFF(next) != off)) 448 { 449 DPFPRINTF(("missing fragment at %d, next %d, max %d\n", 450 off, next == NULL ? -1 : FR_IP_OFF(next), 451 (*frag)->fr_max)); 452 return (NULL); 453 } 454 } 455 DPFPRINTF(("%d < %d?\n", off, (*frag)->fr_max)); 456 if (off < (*frag)->fr_max) 457 return (NULL); 458 459 /* We have all the data */ 460 frent = LIST_FIRST(&(*frag)->fr_queue); 461 KASSERT(frent != NULL); 462 if ((frent->fr_ip->ip_hl << 2) + off > IP_MAXPACKET) { 463 DPFPRINTF(("drop: too big: %d\n", off)); 464 pf_free_fragment(*frag); 465 *frag = NULL; 466 return (NULL); 467 } 468 next = LIST_NEXT(frent, fr_next); 469 470 /* Magic from ip_input */ 471 ip = frent->fr_ip; 472 m = frent->fr_m; 473 m2 = m->m_next; 474 m->m_next = NULL; 475 m_cat(m, m2); 476 pool_put(&pf_frent_pl, frent); 477 pf_nfrents--; 478 for (frent = next; frent != NULL; frent = next) { 479 next = LIST_NEXT(frent, fr_next); 480 481 m2 = frent->fr_m; 482 pool_put(&pf_frent_pl, frent); 483 pf_nfrents--; 484 m_cat(m, m2); 485 } 486 487 ip->ip_src = (*frag)->fr_src; 488 ip->ip_dst = (*frag)->fr_dst; 489 490 /* Remove from fragment queue */ 491 pf_remove_fragment(*frag); 492 *frag = NULL; 493 494 hlen = ip->ip_hl << 2; 495 ip->ip_len = htons(off + hlen); 496 m->m_len += hlen; 497 m->m_data -= hlen; 498 499 /* some debugging cruft by sklower, below, will go away soon */ 500 /* XXX this should be done elsewhere */ 501 if (m->m_flags & M_PKTHDR) { 502 int plen = 0; 503 for (m2 = m; m2; m2 = m2->m_next) 504 plen += m2->m_len; 505 m->m_pkthdr.len = plen; 506 } 507 508 DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len))); 509 return (m); 510 511 drop_fragment: 512 /* Oops - fail safe - drop packet */ 513 pool_put(&pf_frent_pl, frent); 514 pf_nfrents--; 515 m_freem(m); 516 return (NULL); 517 } 518 519 struct mbuf * 520 pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff, 521 int drop, int *nomem) 522 { 523 struct mbuf *m = *m0; 524 struct pf_frcache *frp, *fra, *cur = NULL; 525 int ip_len = ntohs(h->ip_len) - (h->ip_hl << 2); 526 u_int16_t off = ntohs(h->ip_off) << 3; 527 u_int16_t max = ip_len + off; 528 int hosed = 0; 529 530 KASSERT(*frag == NULL || !BUFFER_FRAGMENTS(*frag)); 531 532 /* Create a new range queue for this packet */ 533 if (*frag == NULL) { 534 *frag = pool_get(&pf_cache_pl, PR_NOWAIT); 535 if (*frag == NULL) { 536 pf_flush_fragments(); 537 *frag = pool_get(&pf_cache_pl, PR_NOWAIT); 538 if (*frag == NULL) 539 goto no_mem; 540 } 541 542 /* Get an entry for the queue */ 543 cur = pool_get(&pf_cent_pl, PR_NOWAIT); 544 if (cur == NULL) { 545 pool_put(&pf_cache_pl, *frag); 546 *frag = NULL; 547 goto no_mem; 548 } 549 pf_ncache++; 550 551 (*frag)->fr_flags = PFFRAG_NOBUFFER; 552 (*frag)->fr_max = 0; 553 (*frag)->fr_src = h->ip_src; 554 (*frag)->fr_dst = h->ip_dst; 555 (*frag)->fr_p = h->ip_p; 556 (*frag)->fr_id = h->ip_id; 557 (*frag)->fr_timeout = time_second; 558 559 cur->fr_off = off; 560 cur->fr_end = max; 561 LIST_INIT(&(*frag)->fr_cache); 562 LIST_INSERT_HEAD(&(*frag)->fr_cache, cur, fr_next); 563 564 RB_INSERT(pf_frag_tree, &pf_cache_tree, *frag); 565 TAILQ_INSERT_HEAD(&pf_cachequeue, *frag, frag_next); 566 567 DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max)); 568 569 goto pass; 570 } 571 572 /* 573 * Find a fragment after the current one: 574 * - off contains the real shifted offset. 575 */ 576 frp = NULL; 577 LIST_FOREACH(fra, &(*frag)->fr_cache, fr_next) { 578 if (fra->fr_off > off) 579 break; 580 frp = fra; 581 } 582 583 KASSERT(frp != NULL || fra != NULL); 584 585 if (frp != NULL) { 586 int precut; 587 588 precut = frp->fr_end - off; 589 if (precut >= ip_len) { 590 /* Fragment is entirely a duplicate */ 591 DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n", 592 h->ip_id, frp->fr_off, frp->fr_end, off, max)); 593 goto drop_fragment; 594 } 595 if (precut == 0) { 596 /* They are adjacent. Fixup cache entry */ 597 DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n", 598 h->ip_id, frp->fr_off, frp->fr_end, off, max)); 599 frp->fr_end = max; 600 } else if (precut > 0) { 601 /* The first part of this payload overlaps with a 602 * fragment that has already been passed. 603 * Need to trim off the first part of the payload. 604 * But to do so easily, we need to create another 605 * mbuf to throw the original header into. 606 */ 607 608 DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n", 609 h->ip_id, precut, frp->fr_off, frp->fr_end, off, 610 max)); 611 612 off += precut; 613 max -= precut; 614 /* Update the previous frag to encompass this one */ 615 frp->fr_end = max; 616 617 if (!drop) { 618 /* XXX Optimization opportunity 619 * This is a very heavy way to trim the payload. 620 * we could do it much faster by diddling mbuf 621 * internals but that would be even less legible 622 * than this mbuf magic. For my next trick, 623 * I'll pull a rabbit out of my laptop. 624 */ 625 *m0 = m_copym2(m, 0, h->ip_hl << 2, M_NOWAIT); 626 if (*m0 == NULL) 627 goto no_mem; 628 KASSERT((*m0)->m_next == NULL); 629 m_adj(m, precut + (h->ip_hl << 2)); 630 m_cat(*m0, m); 631 m = *m0; 632 if (m->m_flags & M_PKTHDR) { 633 int plen = 0; 634 struct mbuf *t; 635 for (t = m; t; t = t->m_next) 636 plen += t->m_len; 637 m->m_pkthdr.len = plen; 638 } 639 640 641 h = mtod(m, struct ip *); 642 643 644 KASSERT((int)m->m_len == 645 ntohs(h->ip_len) - precut); 646 h->ip_off = htons(ntohs(h->ip_off) + 647 (precut >> 3)); 648 h->ip_len = htons(ntohs(h->ip_len) - precut); 649 } else { 650 hosed++; 651 } 652 } else { 653 /* There is a gap between fragments */ 654 655 DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n", 656 h->ip_id, -precut, frp->fr_off, frp->fr_end, off, 657 max)); 658 659 cur = pool_get(&pf_cent_pl, PR_NOWAIT); 660 if (cur == NULL) 661 goto no_mem; 662 pf_ncache++; 663 664 cur->fr_off = off; 665 cur->fr_end = max; 666 LIST_INSERT_AFTER(frp, cur, fr_next); 667 } 668 } 669 670 if (fra != NULL) { 671 int aftercut; 672 int merge = 0; 673 674 aftercut = max - fra->fr_off; 675 if (aftercut == 0) { 676 /* Adjacent fragments */ 677 DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n", 678 h->ip_id, off, max, fra->fr_off, fra->fr_end)); 679 fra->fr_off = off; 680 merge = 1; 681 } else if (aftercut > 0) { 682 /* Need to chop off the tail of this fragment */ 683 DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n", 684 h->ip_id, aftercut, off, max, fra->fr_off, 685 fra->fr_end)); 686 fra->fr_off = off; 687 max -= aftercut; 688 689 merge = 1; 690 691 if (!drop) { 692 m_adj(m, -aftercut); 693 if (m->m_flags & M_PKTHDR) { 694 int plen = 0; 695 struct mbuf *t; 696 for (t = m; t; t = t->m_next) 697 plen += t->m_len; 698 m->m_pkthdr.len = plen; 699 } 700 h = mtod(m, struct ip *); 701 KASSERT((int)m->m_len == 702 ntohs(h->ip_len) - aftercut); 703 h->ip_len = htons(ntohs(h->ip_len) - aftercut); 704 } else { 705 hosed++; 706 } 707 } else if (frp == NULL) { 708 /* There is a gap between fragments */ 709 DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n", 710 h->ip_id, -aftercut, off, max, fra->fr_off, 711 fra->fr_end)); 712 713 cur = pool_get(&pf_cent_pl, PR_NOWAIT); 714 if (cur == NULL) 715 goto no_mem; 716 pf_ncache++; 717 718 cur->fr_off = off; 719 cur->fr_end = max; 720 LIST_INSERT_BEFORE(fra, cur, fr_next); 721 } 722 723 724 /* Need to glue together two separate fragment descriptors */ 725 if (merge) { 726 if (cur && fra->fr_off <= cur->fr_end) { 727 /* Need to merge in a previous 'cur' */ 728 DPFPRINTF(("fragcache[%d]: adjacent(merge " 729 "%d-%d) %d-%d (%d-%d)\n", 730 h->ip_id, cur->fr_off, cur->fr_end, off, 731 max, fra->fr_off, fra->fr_end)); 732 fra->fr_off = cur->fr_off; 733 LIST_REMOVE(cur, fr_next); 734 pool_put(&pf_cent_pl, cur); 735 pf_ncache--; 736 cur = NULL; 737 738 } else if (frp && fra->fr_off <= frp->fr_end) { 739 /* Need to merge in a modified 'frp' */ 740 KASSERT(cur == NULL); 741 DPFPRINTF(("fragcache[%d]: adjacent(merge " 742 "%d-%d) %d-%d (%d-%d)\n", 743 h->ip_id, frp->fr_off, frp->fr_end, off, 744 max, fra->fr_off, fra->fr_end)); 745 fra->fr_off = frp->fr_off; 746 LIST_REMOVE(frp, fr_next); 747 pool_put(&pf_cent_pl, frp); 748 pf_ncache--; 749 frp = NULL; 750 751 } 752 } 753 } 754 755 if (hosed) { 756 /* 757 * We must keep tracking the overall fragment even when 758 * we're going to drop it anyway so that we know when to 759 * free the overall descriptor. Thus we drop the frag late. 760 */ 761 goto drop_fragment; 762 } 763 764 765 pass: 766 /* Update maximum data size */ 767 if ((*frag)->fr_max < max) 768 (*frag)->fr_max = max; 769 770 /* This is the last segment */ 771 if (!mff) 772 (*frag)->fr_flags |= PFFRAG_SEENLAST; 773 774 /* Check if we are completely reassembled */ 775 if (((*frag)->fr_flags & PFFRAG_SEENLAST) && 776 LIST_FIRST(&(*frag)->fr_cache)->fr_off == 0 && 777 LIST_FIRST(&(*frag)->fr_cache)->fr_end == (*frag)->fr_max) { 778 /* Remove from fragment queue */ 779 DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id, 780 (*frag)->fr_max)); 781 pf_free_fragment(*frag); 782 *frag = NULL; 783 } 784 785 return (m); 786 787 no_mem: 788 *nomem = 1; 789 790 /* Still need to pay attention to !IP_MF */ 791 if (!mff && *frag != NULL) 792 (*frag)->fr_flags |= PFFRAG_SEENLAST; 793 794 m_freem(m); 795 return (NULL); 796 797 drop_fragment: 798 799 /* Still need to pay attention to !IP_MF */ 800 if (!mff && *frag != NULL) 801 (*frag)->fr_flags |= PFFRAG_SEENLAST; 802 803 if (drop) { 804 /* This fragment has been deemed bad. Don't reass */ 805 if (((*frag)->fr_flags & PFFRAG_DROP) == 0) 806 DPFPRINTF(("fragcache[%d]: dropping overall fragment\n", 807 h->ip_id)); 808 (*frag)->fr_flags |= PFFRAG_DROP; 809 } 810 811 m_freem(m); 812 return (NULL); 813 } 814 815 int 816 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason, 817 struct pf_pdesc *pd) 818 { 819 struct mbuf *m = *m0; 820 struct pf_rule *r; 821 struct pf_frent *frent; 822 struct pf_fragment *frag = NULL; 823 struct ip *h = mtod(m, struct ip *); 824 int mff = (ntohs(h->ip_off) & IP_MF); 825 int hlen = h->ip_hl << 2; 826 u_int16_t fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3; 827 u_int16_t max; 828 int ip_len; 829 int ip_off; 830 int tag = -1; 831 832 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 833 while (r != NULL) { 834 r->evaluations++; 835 if (pfi_kif_match(r->kif, kif) == r->ifnot) 836 r = r->skip[PF_SKIP_IFP].ptr; 837 else if (r->direction && r->direction != dir) 838 r = r->skip[PF_SKIP_DIR].ptr; 839 else if (r->af && r->af != AF_INET) 840 r = r->skip[PF_SKIP_AF].ptr; 841 else if (r->proto && r->proto != h->ip_p) 842 r = r->skip[PF_SKIP_PROTO].ptr; 843 else if (PF_MISMATCHAW(&r->src.addr, 844 (struct pf_addr *)&h->ip_src.s_addr, AF_INET, 845 r->src.neg, kif)) 846 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 847 else if (PF_MISMATCHAW(&r->dst.addr, 848 (struct pf_addr *)&h->ip_dst.s_addr, AF_INET, 849 r->dst.neg, NULL)) 850 r = r->skip[PF_SKIP_DST_ADDR].ptr; 851 else if (r->match_tag && !pf_match_tag(m, r, &tag)) 852 r = TAILQ_NEXT(r, entries); 853 else 854 break; 855 } 856 857 if (r == NULL || r->action == PF_NOSCRUB) 858 return (PF_PASS); 859 else { 860 r->packets[dir == PF_OUT]++; 861 r->bytes[dir == PF_OUT] += pd->tot_len; 862 } 863 864 /* Check for illegal packets */ 865 if (hlen < (int)sizeof(struct ip)) 866 goto drop; 867 868 if (hlen > ntohs(h->ip_len)) 869 goto drop; 870 871 /* Clear IP_DF if the rule uses the no-df option */ 872 if (r->rule_flag & PFRULE_NODF && h->ip_off & htons(IP_DF)) { 873 u_int16_t ip_off = h->ip_off; 874 875 h->ip_off &= htons(~IP_DF); 876 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 877 } 878 879 /* We will need other tests here */ 880 if (!fragoff && !mff) 881 goto no_fragment; 882 883 /* We're dealing with a fragment now. Don't allow fragments 884 * with IP_DF to enter the cache. If the flag was cleared by 885 * no-df above, fine. Otherwise drop it. 886 */ 887 if (h->ip_off & htons(IP_DF)) { 888 DPFPRINTF(("IP_DF\n")); 889 goto bad; 890 } 891 892 ip_len = ntohs(h->ip_len) - hlen; 893 ip_off = (ntohs(h->ip_off) & IP_OFFMASK) << 3; 894 895 /* All fragments are 8 byte aligned */ 896 if (mff && (ip_len & 0x7)) { 897 DPFPRINTF(("mff and %d\n", ip_len)); 898 goto bad; 899 } 900 901 /* Respect maximum length */ 902 if (fragoff + ip_len > IP_MAXPACKET) { 903 DPFPRINTF(("max packet %d\n", fragoff + ip_len)); 904 goto bad; 905 } 906 max = fragoff + ip_len; 907 908 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) { 909 /* Fully buffer all of the fragments */ 910 911 frag = pf_find_fragment(h, &pf_frag_tree); 912 913 /* Check if we saw the last fragment already */ 914 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 915 max > frag->fr_max) 916 goto bad; 917 918 /* Get an entry for the fragment queue */ 919 frent = pool_get(&pf_frent_pl, PR_NOWAIT); 920 if (frent == NULL) { 921 REASON_SET(reason, PFRES_MEMORY); 922 return (PF_DROP); 923 } 924 pf_nfrents++; 925 frent->fr_ip = h; 926 frent->fr_m = m; 927 928 /* Might return a completely reassembled mbuf, or NULL */ 929 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max)); 930 *m0 = m = pf_reassemble(m0, &frag, frent, mff); 931 932 if (m == NULL) 933 return (PF_DROP); 934 935 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP)) 936 goto drop; 937 938 h = mtod(m, struct ip *); 939 } else { 940 /* non-buffering fragment cache (drops or masks overlaps) */ 941 int nomem = 0; 942 943 if (dir == PF_OUT && m->m_pkthdr.pf.flags & PF_TAG_FRAGCACHE) { 944 /* 945 * Already passed the fragment cache in the 946 * input direction. If we continued, it would 947 * appear to be a dup and would be dropped. 948 */ 949 goto fragment_pass; 950 } 951 952 frag = pf_find_fragment(h, &pf_cache_tree); 953 954 /* Check if we saw the last fragment already */ 955 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 956 max > frag->fr_max) { 957 if (r->rule_flag & PFRULE_FRAGDROP) 958 frag->fr_flags |= PFFRAG_DROP; 959 goto bad; 960 } 961 962 *m0 = m = pf_fragcache(m0, h, &frag, mff, 963 (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem); 964 if (m == NULL) { 965 if (nomem) 966 goto no_mem; 967 goto drop; 968 } 969 970 if (dir == PF_IN) 971 m->m_pkthdr.pf.flags |= PF_TAG_FRAGCACHE; 972 973 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP)) 974 goto drop; 975 goto fragment_pass; 976 } 977 978 no_fragment: 979 /* At this point, only IP_DF is allowed in ip_off */ 980 if (h->ip_off & ~htons(IP_DF)) { 981 u_int16_t ip_off = h->ip_off; 982 983 h->ip_off &= htons(IP_DF); 984 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 985 } 986 987 /* Enforce a minimum ttl, may cause endless packet loops */ 988 if (r->min_ttl && h->ip_ttl < r->min_ttl) { 989 u_int16_t ip_ttl = h->ip_ttl; 990 991 h->ip_ttl = r->min_ttl; 992 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0); 993 } 994 995 /* Enforce tos */ 996 if (r->rule_flag & PFRULE_SET_TOS) { 997 u_int16_t ov, nv; 998 999 ov = *(u_int16_t *)h; 1000 h->ip_tos = r->set_tos; 1001 nv = *(u_int16_t *)h; 1002 1003 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0); 1004 } 1005 1006 if (r->rule_flag & PFRULE_RANDOMID) { 1007 u_int16_t ip_id = h->ip_id; 1008 1009 h->ip_id = ip_randomid(); 1010 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0); 1011 } 1012 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) 1013 pd->flags |= PFDESC_IP_REAS; 1014 1015 return (PF_PASS); 1016 1017 fragment_pass: 1018 /* Enforce a minimum ttl, may cause endless packet loops */ 1019 if (r->min_ttl && h->ip_ttl < r->min_ttl) { 1020 u_int16_t ip_ttl = h->ip_ttl; 1021 1022 h->ip_ttl = r->min_ttl; 1023 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0); 1024 } 1025 /* Enforce tos */ 1026 if (r->rule_flag & PFRULE_SET_TOS) { 1027 u_int16_t ov, nv; 1028 1029 ov = *(u_int16_t *)h; 1030 h->ip_tos = r->set_tos; 1031 nv = *(u_int16_t *)h; 1032 1033 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0); 1034 } 1035 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) 1036 pd->flags |= PFDESC_IP_REAS; 1037 return (PF_PASS); 1038 1039 no_mem: 1040 REASON_SET(reason, PFRES_MEMORY); 1041 if (r != NULL && r->log) 1042 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL, pd); 1043 return (PF_DROP); 1044 1045 drop: 1046 REASON_SET(reason, PFRES_NORM); 1047 if (r != NULL && r->log) 1048 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL, pd); 1049 return (PF_DROP); 1050 1051 bad: 1052 DPFPRINTF(("dropping bad fragment\n")); 1053 1054 /* Free associated fragments */ 1055 if (frag != NULL) 1056 pf_free_fragment(frag); 1057 1058 REASON_SET(reason, PFRES_FRAG); 1059 if (r != NULL && r->log) 1060 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL, pd); 1061 1062 return (PF_DROP); 1063 } 1064 1065 #ifdef INET6 1066 int 1067 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif, 1068 u_short *reason, struct pf_pdesc *pd) 1069 { 1070 struct mbuf *m = *m0; 1071 struct pf_rule *r; 1072 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1073 int off; 1074 struct ip6_ext ext; 1075 struct ip6_opt opt; 1076 struct ip6_opt_jumbo jumbo; 1077 struct ip6_frag frag; 1078 u_int32_t jumbolen = 0, plen; 1079 u_int16_t fragoff = 0; 1080 int optend; 1081 int ooff; 1082 u_int8_t proto; 1083 int terminal; 1084 1085 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1086 while (r != NULL) { 1087 r->evaluations++; 1088 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1089 r = r->skip[PF_SKIP_IFP].ptr; 1090 else if (r->direction && r->direction != dir) 1091 r = r->skip[PF_SKIP_DIR].ptr; 1092 else if (r->af && r->af != AF_INET6) 1093 r = r->skip[PF_SKIP_AF].ptr; 1094 #if 0 /* header chain! */ 1095 else if (r->proto && r->proto != h->ip6_nxt) 1096 r = r->skip[PF_SKIP_PROTO].ptr; 1097 #endif 1098 else if (PF_MISMATCHAW(&r->src.addr, 1099 (struct pf_addr *)&h->ip6_src, AF_INET6, 1100 r->src.neg, kif)) 1101 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1102 else if (PF_MISMATCHAW(&r->dst.addr, 1103 (struct pf_addr *)&h->ip6_dst, AF_INET6, 1104 r->dst.neg, NULL)) 1105 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1106 else 1107 break; 1108 } 1109 1110 if (r == NULL || r->action == PF_NOSCRUB) 1111 return (PF_PASS); 1112 else { 1113 r->packets[dir == PF_OUT]++; 1114 r->bytes[dir == PF_OUT] += pd->tot_len; 1115 } 1116 1117 /* Check for illegal packets */ 1118 if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len) 1119 goto drop; 1120 1121 off = sizeof(struct ip6_hdr); 1122 proto = h->ip6_nxt; 1123 terminal = 0; 1124 do { 1125 switch (proto) { 1126 case IPPROTO_FRAGMENT: 1127 goto fragment; 1128 break; 1129 case IPPROTO_AH: 1130 case IPPROTO_ROUTING: 1131 case IPPROTO_DSTOPTS: 1132 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1133 NULL, AF_INET6)) 1134 goto shortpkt; 1135 if (proto == IPPROTO_AH) 1136 off += (ext.ip6e_len + 2) * 4; 1137 else 1138 off += (ext.ip6e_len + 1) * 8; 1139 proto = ext.ip6e_nxt; 1140 break; 1141 case IPPROTO_HOPOPTS: 1142 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1143 NULL, AF_INET6)) 1144 goto shortpkt; 1145 optend = off + (ext.ip6e_len + 1) * 8; 1146 ooff = off + sizeof(ext); 1147 do { 1148 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type, 1149 sizeof(opt.ip6o_type), NULL, NULL, 1150 AF_INET6)) 1151 goto shortpkt; 1152 if (opt.ip6o_type == IP6OPT_PAD1) { 1153 ooff++; 1154 continue; 1155 } 1156 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt), 1157 NULL, NULL, AF_INET6)) 1158 goto shortpkt; 1159 if (ooff + sizeof(opt) + opt.ip6o_len > optend) 1160 goto drop; 1161 switch (opt.ip6o_type) { 1162 case IP6OPT_JUMBO: 1163 if (h->ip6_plen != 0) 1164 goto drop; 1165 if (!pf_pull_hdr(m, ooff, &jumbo, 1166 sizeof(jumbo), NULL, NULL, 1167 AF_INET6)) 1168 goto shortpkt; 1169 memcpy(&jumbolen, jumbo.ip6oj_jumbo_len, 1170 sizeof(jumbolen)); 1171 jumbolen = ntohl(jumbolen); 1172 if (jumbolen <= IPV6_MAXPACKET) 1173 goto drop; 1174 if (sizeof(struct ip6_hdr) + jumbolen != 1175 m->m_pkthdr.len) 1176 goto drop; 1177 break; 1178 default: 1179 break; 1180 } 1181 ooff += sizeof(opt) + opt.ip6o_len; 1182 } while (ooff < optend); 1183 1184 off = optend; 1185 proto = ext.ip6e_nxt; 1186 break; 1187 default: 1188 terminal = 1; 1189 break; 1190 } 1191 } while (!terminal); 1192 1193 /* jumbo payload option must be present, or plen > 0 */ 1194 if (ntohs(h->ip6_plen) == 0) 1195 plen = jumbolen; 1196 else 1197 plen = ntohs(h->ip6_plen); 1198 if (plen == 0) 1199 goto drop; 1200 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1201 goto shortpkt; 1202 1203 /* Enforce a minimum ttl, may cause endless packet loops */ 1204 if (r->min_ttl && h->ip6_hlim < r->min_ttl) 1205 h->ip6_hlim = r->min_ttl; 1206 1207 return (PF_PASS); 1208 1209 fragment: 1210 if (ntohs(h->ip6_plen) == 0 || jumbolen) 1211 goto drop; 1212 plen = ntohs(h->ip6_plen); 1213 1214 if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6)) 1215 goto shortpkt; 1216 fragoff = ntohs(frag.ip6f_offlg & IP6F_OFF_MASK); 1217 if (fragoff + (plen - off - sizeof(frag)) > IPV6_MAXPACKET) 1218 goto badfrag; 1219 1220 /* do something about it */ 1221 /* remember to set pd->flags |= PFDESC_IP_REAS */ 1222 return (PF_PASS); 1223 1224 shortpkt: 1225 REASON_SET(reason, PFRES_SHORT); 1226 if (r != NULL && r->log) 1227 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL, pd); 1228 return (PF_DROP); 1229 1230 drop: 1231 REASON_SET(reason, PFRES_NORM); 1232 if (r != NULL && r->log) 1233 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL, pd); 1234 return (PF_DROP); 1235 1236 badfrag: 1237 REASON_SET(reason, PFRES_FRAG); 1238 if (r != NULL && r->log) 1239 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL, pd); 1240 return (PF_DROP); 1241 } 1242 #endif /* INET6 */ 1243 1244 int 1245 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff, 1246 int off, void *h, struct pf_pdesc *pd) 1247 { 1248 struct pf_rule *r, *rm = NULL; 1249 struct tcphdr *th = pd->hdr.tcp; 1250 int rewrite = 0; 1251 u_short reason; 1252 u_int8_t flags; 1253 sa_family_t af = pd->af; 1254 1255 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1256 while (r != NULL) { 1257 r->evaluations++; 1258 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1259 r = r->skip[PF_SKIP_IFP].ptr; 1260 else if (r->direction && r->direction != dir) 1261 r = r->skip[PF_SKIP_DIR].ptr; 1262 else if (r->af && r->af != af) 1263 r = r->skip[PF_SKIP_AF].ptr; 1264 else if (r->proto && r->proto != pd->proto) 1265 r = r->skip[PF_SKIP_PROTO].ptr; 1266 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, 1267 r->src.neg, kif)) 1268 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1269 else if (r->src.port_op && !pf_match_port(r->src.port_op, 1270 r->src.port[0], r->src.port[1], th->th_sport)) 1271 r = r->skip[PF_SKIP_SRC_PORT].ptr; 1272 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, 1273 r->dst.neg, NULL)) 1274 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1275 else if (r->dst.port_op && !pf_match_port(r->dst.port_op, 1276 r->dst.port[0], r->dst.port[1], th->th_dport)) 1277 r = r->skip[PF_SKIP_DST_PORT].ptr; 1278 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match( 1279 pf_osfp_fingerprint(pd, m, off, th), 1280 r->os_fingerprint)) 1281 r = TAILQ_NEXT(r, entries); 1282 else { 1283 rm = r; 1284 break; 1285 } 1286 } 1287 1288 if (rm == NULL || rm->action == PF_NOSCRUB) 1289 return (PF_PASS); 1290 else { 1291 r->packets[dir == PF_OUT]++; 1292 r->bytes[dir == PF_OUT] += pd->tot_len; 1293 } 1294 1295 if (rm->rule_flag & PFRULE_REASSEMBLE_TCP) 1296 pd->flags |= PFDESC_TCP_NORM; 1297 1298 flags = th->th_flags; 1299 if (flags & TH_SYN) { 1300 /* Illegal packet */ 1301 if (flags & TH_RST) 1302 goto tcp_drop; 1303 1304 if (flags & TH_FIN) 1305 flags &= ~TH_FIN; 1306 } else { 1307 /* Illegal packet */ 1308 if (!(flags & (TH_ACK|TH_RST))) 1309 goto tcp_drop; 1310 } 1311 1312 if (!(flags & TH_ACK)) { 1313 /* These flags are only valid if ACK is set */ 1314 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG)) 1315 goto tcp_drop; 1316 } 1317 1318 /* Check for illegal header length */ 1319 if (th->th_off < (sizeof(struct tcphdr) >> 2)) 1320 goto tcp_drop; 1321 1322 /* If flags changed, or reserved data set, then adjust */ 1323 if (flags != th->th_flags || th->th_x2 != 0) { 1324 u_int16_t ov, nv; 1325 1326 ov = *(u_int16_t *)(&th->th_ack + 1); 1327 th->th_flags = flags; 1328 th->th_x2 = 0; 1329 nv = *(u_int16_t *)(&th->th_ack + 1); 1330 1331 th->th_sum = pf_cksum_fixup(th->th_sum, ov, nv, 0); 1332 rewrite = 1; 1333 } 1334 1335 /* Remove urgent pointer, if TH_URG is not set */ 1336 if (!(flags & TH_URG) && th->th_urp) { 1337 th->th_sum = pf_cksum_fixup(th->th_sum, th->th_urp, 0, 0); 1338 th->th_urp = 0; 1339 rewrite = 1; 1340 } 1341 1342 /* Process options */ 1343 if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af)) 1344 rewrite = 1; 1345 1346 /* copy back packet headers if we sanitized */ 1347 if (rewrite) 1348 m_copyback(m, off, sizeof(*th), th); 1349 1350 return (PF_PASS); 1351 1352 tcp_drop: 1353 REASON_SET(&reason, PFRES_NORM); 1354 if (rm != NULL && r->log) 1355 PFLOG_PACKET(kif, h, m, AF_INET, dir, reason, r, NULL, NULL, pd); 1356 return (PF_DROP); 1357 } 1358 1359 int 1360 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd, 1361 struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst) 1362 { 1363 u_int32_t tsval, tsecr; 1364 u_int8_t hdr[60]; 1365 u_int8_t *opt; 1366 1367 KASSERT(src->scrub == NULL); 1368 1369 src->scrub = pool_get(&pf_state_scrub_pl, PR_NOWAIT); 1370 if (src->scrub == NULL) 1371 return (1); 1372 bzero(src->scrub, sizeof(*src->scrub)); 1373 1374 switch (pd->af) { 1375 #ifdef INET 1376 case AF_INET: { 1377 struct ip *h = mtod(m, struct ip *); 1378 src->scrub->pfss_ttl = h->ip_ttl; 1379 break; 1380 } 1381 #endif /* INET */ 1382 #ifdef INET6 1383 case AF_INET6: { 1384 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1385 src->scrub->pfss_ttl = h->ip6_hlim; 1386 break; 1387 } 1388 #endif /* INET6 */ 1389 } 1390 1391 1392 /* 1393 * All normalizations below are only begun if we see the start of 1394 * the connections. They must all set an enabled bit in pfss_flags 1395 */ 1396 if ((th->th_flags & TH_SYN) == 0) 1397 return (0); 1398 1399 1400 if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub && 1401 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1402 /* Diddle with TCP options */ 1403 int hlen; 1404 opt = hdr + sizeof(struct tcphdr); 1405 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1406 while (hlen >= TCPOLEN_TIMESTAMP) { 1407 switch (*opt) { 1408 case TCPOPT_EOL: /* FALLTHROUGH */ 1409 case TCPOPT_NOP: 1410 opt++; 1411 hlen--; 1412 break; 1413 case TCPOPT_TIMESTAMP: 1414 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1415 src->scrub->pfss_flags |= 1416 PFSS_TIMESTAMP; 1417 src->scrub->pfss_ts_mod = 1418 htonl(arc4random()); 1419 1420 /* note PFSS_PAWS not set yet */ 1421 memcpy(&tsval, &opt[2], 1422 sizeof(u_int32_t)); 1423 memcpy(&tsecr, &opt[6], 1424 sizeof(u_int32_t)); 1425 src->scrub->pfss_tsval0 = ntohl(tsval); 1426 src->scrub->pfss_tsval = ntohl(tsval); 1427 src->scrub->pfss_tsecr = ntohl(tsecr); 1428 getmicrouptime(&src->scrub->pfss_last); 1429 } 1430 /* FALLTHROUGH */ 1431 default: 1432 hlen -= MAX(opt[1], 2); 1433 opt += MAX(opt[1], 2); 1434 break; 1435 } 1436 } 1437 } 1438 1439 return (0); 1440 } 1441 1442 void 1443 pf_normalize_tcp_cleanup(struct pf_state *state) 1444 { 1445 if (state->src.scrub) 1446 pool_put(&pf_state_scrub_pl, state->src.scrub); 1447 if (state->dst.scrub) 1448 pool_put(&pf_state_scrub_pl, state->dst.scrub); 1449 1450 /* Someday... flush the TCP segment reassembly descriptors. */ 1451 } 1452 1453 int 1454 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd, 1455 u_short *reason, struct tcphdr *th, struct pf_state *state, 1456 struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback) 1457 { 1458 struct timeval uptime; 1459 u_int32_t tsval, tsecr; 1460 u_int tsval_from_last; 1461 u_int8_t hdr[60]; 1462 u_int8_t *opt; 1463 int copyback = 0; 1464 int got_ts = 0; 1465 1466 KASSERT(src->scrub || dst->scrub); 1467 1468 /* 1469 * Enforce the minimum TTL seen for this connection. Negate a common 1470 * technique to evade an intrusion detection system and confuse 1471 * firewall state code. 1472 */ 1473 switch (pd->af) { 1474 #ifdef INET 1475 case AF_INET: { 1476 if (src->scrub) { 1477 struct ip *h = mtod(m, struct ip *); 1478 if (h->ip_ttl > src->scrub->pfss_ttl) 1479 src->scrub->pfss_ttl = h->ip_ttl; 1480 h->ip_ttl = src->scrub->pfss_ttl; 1481 } 1482 break; 1483 } 1484 #endif /* INET */ 1485 #ifdef INET6 1486 case AF_INET6: { 1487 if (src->scrub) { 1488 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1489 if (h->ip6_hlim > src->scrub->pfss_ttl) 1490 src->scrub->pfss_ttl = h->ip6_hlim; 1491 h->ip6_hlim = src->scrub->pfss_ttl; 1492 } 1493 break; 1494 } 1495 #endif /* INET6 */ 1496 } 1497 1498 if (th->th_off > (sizeof(struct tcphdr) >> 2) && 1499 ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) || 1500 (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) && 1501 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1502 /* Diddle with TCP options */ 1503 int hlen; 1504 opt = hdr + sizeof(struct tcphdr); 1505 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1506 while (hlen >= TCPOLEN_TIMESTAMP) { 1507 switch (*opt) { 1508 case TCPOPT_EOL: /* FALLTHROUGH */ 1509 case TCPOPT_NOP: 1510 opt++; 1511 hlen--; 1512 break; 1513 case TCPOPT_TIMESTAMP: 1514 /* Modulate the timestamps. Can be used for 1515 * NAT detection, OS uptime determination or 1516 * reboot detection. 1517 */ 1518 1519 if (got_ts) { 1520 /* Huh? Multiple timestamps!? */ 1521 if (pf_status.debug >= PF_DEBUG_MISC) { 1522 DPFPRINTF(("multiple TS??")); 1523 pf_print_state(state); 1524 printf("\n"); 1525 } 1526 REASON_SET(reason, PFRES_TS); 1527 return (PF_DROP); 1528 } 1529 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1530 memcpy(&tsval, &opt[2], 1531 sizeof(u_int32_t)); 1532 if (tsval && src->scrub && 1533 (src->scrub->pfss_flags & 1534 PFSS_TIMESTAMP)) { 1535 tsval = ntohl(tsval); 1536 pf_change_a(&opt[2], 1537 &th->th_sum, 1538 htonl(tsval + 1539 src->scrub->pfss_ts_mod), 1540 0); 1541 copyback = 1; 1542 } 1543 1544 /* Modulate TS reply iff valid (!0) */ 1545 memcpy(&tsecr, &opt[6], 1546 sizeof(u_int32_t)); 1547 if (tsecr && dst->scrub && 1548 (dst->scrub->pfss_flags & 1549 PFSS_TIMESTAMP)) { 1550 tsecr = ntohl(tsecr) 1551 - dst->scrub->pfss_ts_mod; 1552 pf_change_a(&opt[6], 1553 &th->th_sum, htonl(tsecr), 1554 0); 1555 copyback = 1; 1556 } 1557 got_ts = 1; 1558 } 1559 /* FALLTHROUGH */ 1560 default: 1561 hlen -= MAX(opt[1], 2); 1562 opt += MAX(opt[1], 2); 1563 break; 1564 } 1565 } 1566 if (copyback) { 1567 /* Copyback the options, caller copys back header */ 1568 *writeback = 1; 1569 m_copyback(m, off + sizeof(struct tcphdr), 1570 (th->th_off << 2) - sizeof(struct tcphdr), hdr + 1571 sizeof(struct tcphdr)); 1572 } 1573 } 1574 1575 1576 /* 1577 * Must invalidate PAWS checks on connections idle for too long. 1578 * The fastest allowed timestamp clock is 1ms. That turns out to 1579 * be about 24 days before it wraps. XXX Right now our lowerbound 1580 * TS echo check only works for the first 12 days of a connection 1581 * when the TS has exhausted half its 32bit space 1582 */ 1583 #define TS_MAX_IDLE (24*24*60*60) 1584 #define TS_MAX_CONN (12*24*60*60) /* XXX remove when better tsecr check */ 1585 1586 getmicrouptime(&uptime); 1587 if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) && 1588 (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE || 1589 time_second - state->creation > TS_MAX_CONN)) { 1590 if (pf_status.debug >= PF_DEBUG_MISC) { 1591 DPFPRINTF(("src idled out of PAWS\n")); 1592 pf_print_state(state); 1593 printf("\n"); 1594 } 1595 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS) 1596 | PFSS_PAWS_IDLED; 1597 } 1598 if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) && 1599 uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) { 1600 if (pf_status.debug >= PF_DEBUG_MISC) { 1601 DPFPRINTF(("dst idled out of PAWS\n")); 1602 pf_print_state(state); 1603 printf("\n"); 1604 } 1605 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS) 1606 | PFSS_PAWS_IDLED; 1607 } 1608 1609 if (got_ts && src->scrub && dst->scrub && 1610 (src->scrub->pfss_flags & PFSS_PAWS) && 1611 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1612 /* Validate that the timestamps are "in-window". 1613 * RFC1323 describes TCP Timestamp options that allow 1614 * measurement of RTT (round trip time) and PAWS 1615 * (protection against wrapped sequence numbers). PAWS 1616 * gives us a set of rules for rejecting packets on 1617 * long fat pipes (packets that were somehow delayed 1618 * in transit longer than the time it took to send the 1619 * full TCP sequence space of 4Gb). We can use these 1620 * rules and infer a few others that will let us treat 1621 * the 32bit timestamp and the 32bit echoed timestamp 1622 * as sequence numbers to prevent a blind attacker from 1623 * inserting packets into a connection. 1624 * 1625 * RFC1323 tells us: 1626 * - The timestamp on this packet must be greater than 1627 * or equal to the last value echoed by the other 1628 * endpoint. The RFC says those will be discarded 1629 * since it is a dup that has already been acked. 1630 * This gives us a lowerbound on the timestamp. 1631 * timestamp >= other last echoed timestamp 1632 * - The timestamp will be less than or equal to 1633 * the last timestamp plus the time between the 1634 * last packet and now. The RFC defines the max 1635 * clock rate as 1ms. We will allow clocks to be 1636 * up to 10% fast and will allow a total difference 1637 * or 30 seconds due to a route change. And this 1638 * gives us an upperbound on the timestamp. 1639 * timestamp <= last timestamp + max ticks 1640 * We have to be careful here. Windows will send an 1641 * initial timestamp of zero and then initialize it 1642 * to a random value after the 3whs; presumably to 1643 * avoid a DoS by having to call an expensive RNG 1644 * during a SYN flood. Proof MS has at least one 1645 * good security geek. 1646 * 1647 * - The TCP timestamp option must also echo the other 1648 * endpoints timestamp. The timestamp echoed is the 1649 * one carried on the earliest unacknowledged segment 1650 * on the left edge of the sequence window. The RFC 1651 * states that the host will reject any echoed 1652 * timestamps that were larger than any ever sent. 1653 * This gives us an upperbound on the TS echo. 1654 * tescr <= largest_tsval 1655 * - The lowerbound on the TS echo is a little more 1656 * tricky to determine. The other endpoint's echoed 1657 * values will not decrease. But there may be 1658 * network conditions that re-order packets and 1659 * cause our view of them to decrease. For now the 1660 * only lowerbound we can safely determine is that 1661 * the TS echo will never be less than the original 1662 * TS. XXX There is probably a better lowerbound. 1663 * Remove TS_MAX_CONN with better lowerbound check. 1664 * tescr >= other original TS 1665 * 1666 * It is also important to note that the fastest 1667 * timestamp clock of 1ms will wrap its 32bit space in 1668 * 24 days. So we just disable TS checking after 24 1669 * days of idle time. We actually must use a 12d 1670 * connection limit until we can come up with a better 1671 * lowerbound to the TS echo check. 1672 */ 1673 struct timeval delta_ts; 1674 int ts_fudge; 1675 1676 1677 /* 1678 * PFTM_TS_DIFF is how many seconds of leeway to allow 1679 * a host's timestamp. This can happen if the previous 1680 * packet got delayed in transit for much longer than 1681 * this packet. 1682 */ 1683 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0) 1684 ts_fudge = pf_default_rule.timeout[PFTM_TS_DIFF]; 1685 1686 1687 /* Calculate max ticks since the last timestamp */ 1688 #define TS_MAXFREQ 1100 /* RFC max TS freq of 1Khz + 10% skew */ 1689 #define TS_MICROSECS 1000000 /* microseconds per second */ 1690 timersub(&uptime, &src->scrub->pfss_last, &delta_ts); 1691 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ; 1692 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ); 1693 1694 1695 if ((src->state >= TCPS_ESTABLISHED && 1696 dst->state >= TCPS_ESTABLISHED) && 1697 (SEQ_LT(tsval, dst->scrub->pfss_tsecr) || 1698 SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) || 1699 (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) || 1700 SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) { 1701 /* Bad RFC1323 implementation or an insertion attack. 1702 * 1703 * - Solaris 2.6 and 2.7 are known to send another ACK 1704 * after the FIN,FIN|ACK,ACK closing that carries 1705 * an old timestamp. 1706 */ 1707 1708 DPFPRINTF(("Timestamp failed %c%c%c%c\n", 1709 SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ', 1710 SEQ_GT(tsval, src->scrub->pfss_tsval + 1711 tsval_from_last) ? '1' : ' ', 1712 SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ', 1713 SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' ')); 1714 DPFPRINTF((" tsval: %lu tsecr: %lu +ticks: %lu " 1715 "idle: %lus %lums\n", 1716 tsval, tsecr, tsval_from_last, delta_ts.tv_sec, 1717 delta_ts.tv_usec / 1000)); 1718 DPFPRINTF((" src->tsval: %lu tsecr: %lu\n", 1719 src->scrub->pfss_tsval, src->scrub->pfss_tsecr)); 1720 DPFPRINTF((" dst->tsval: %lu tsecr: %lu tsval0: %lu" 1721 "\n", dst->scrub->pfss_tsval, 1722 dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0)); 1723 if (pf_status.debug >= PF_DEBUG_MISC) { 1724 pf_print_state(state); 1725 pf_print_flags(th->th_flags); 1726 printf("\n"); 1727 } 1728 REASON_SET(reason, PFRES_TS); 1729 return (PF_DROP); 1730 } 1731 1732 /* XXX I'd really like to require tsecr but it's optional */ 1733 1734 } else if (!got_ts && (th->th_flags & TH_RST) == 0 && 1735 ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED) 1736 || pd->p_len > 0 || (th->th_flags & TH_SYN)) && 1737 src->scrub && dst->scrub && 1738 (src->scrub->pfss_flags & PFSS_PAWS) && 1739 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1740 /* Didn't send a timestamp. Timestamps aren't really useful 1741 * when: 1742 * - connection opening or closing (often not even sent). 1743 * but we must not let an attacker to put a FIN on a 1744 * data packet to sneak it through our ESTABLISHED check. 1745 * - on a TCP reset. RFC suggests not even looking at TS. 1746 * - on an empty ACK. The TS will not be echoed so it will 1747 * probably not help keep the RTT calculation in sync and 1748 * there isn't as much danger when the sequence numbers 1749 * got wrapped. So some stacks don't include TS on empty 1750 * ACKs :-( 1751 * 1752 * To minimize the disruption to mostly RFC1323 conformant 1753 * stacks, we will only require timestamps on data packets. 1754 * 1755 * And what do ya know, we cannot require timestamps on data 1756 * packets. There appear to be devices that do legitimate 1757 * TCP connection hijacking. There are HTTP devices that allow 1758 * a 3whs (with timestamps) and then buffer the HTTP request. 1759 * If the intermediate device has the HTTP response cache, it 1760 * will spoof the response but not bother timestamping its 1761 * packets. So we can look for the presence of a timestamp in 1762 * the first data packet and if there, require it in all future 1763 * packets. 1764 */ 1765 1766 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) { 1767 /* 1768 * Hey! Someone tried to sneak a packet in. Or the 1769 * stack changed its RFC1323 behavior?!?! 1770 */ 1771 if (pf_status.debug >= PF_DEBUG_MISC) { 1772 DPFPRINTF(("Did not receive expected RFC1323 " 1773 "timestamp\n")); 1774 pf_print_state(state); 1775 pf_print_flags(th->th_flags); 1776 printf("\n"); 1777 } 1778 REASON_SET(reason, PFRES_TS); 1779 return (PF_DROP); 1780 } 1781 } 1782 1783 1784 /* 1785 * We will note if a host sends his data packets with or without 1786 * timestamps. And require all data packets to contain a timestamp 1787 * if the first does. PAWS implicitly requires that all data packets be 1788 * timestamped. But I think there are middle-man devices that hijack 1789 * TCP streams immediately after the 3whs and don't timestamp their 1790 * packets (seen in a WWW accelerator or cache). 1791 */ 1792 if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags & 1793 (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) { 1794 if (got_ts) 1795 src->scrub->pfss_flags |= PFSS_DATA_TS; 1796 else { 1797 src->scrub->pfss_flags |= PFSS_DATA_NOTS; 1798 if (pf_status.debug >= PF_DEBUG_MISC && dst->scrub && 1799 (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) { 1800 /* Don't warn if other host rejected RFC1323 */ 1801 DPFPRINTF(("Broken RFC1323 stack did not " 1802 "timestamp data packet. Disabled PAWS " 1803 "security.\n")); 1804 pf_print_state(state); 1805 pf_print_flags(th->th_flags); 1806 printf("\n"); 1807 } 1808 } 1809 } 1810 1811 1812 /* 1813 * Update PAWS values 1814 */ 1815 if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags & 1816 (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) { 1817 getmicrouptime(&src->scrub->pfss_last); 1818 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) || 1819 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 1820 src->scrub->pfss_tsval = tsval; 1821 1822 if (tsecr) { 1823 if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) || 1824 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 1825 src->scrub->pfss_tsecr = tsecr; 1826 1827 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 && 1828 (SEQ_LT(tsval, src->scrub->pfss_tsval0) || 1829 src->scrub->pfss_tsval0 == 0)) { 1830 /* tsval0 MUST be the lowest timestamp */ 1831 src->scrub->pfss_tsval0 = tsval; 1832 } 1833 1834 /* Only fully initialized after a TS gets echoed */ 1835 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0) 1836 src->scrub->pfss_flags |= PFSS_PAWS; 1837 } 1838 } 1839 1840 /* I have a dream.... TCP segment reassembly.... */ 1841 return (0); 1842 } 1843 1844 int 1845 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th, 1846 int off, sa_family_t af) 1847 { 1848 u_int16_t *mss; 1849 int thoff; 1850 int opt, cnt, optlen = 0; 1851 int rewrite = 0; 1852 u_char opts[MAX_TCPOPTLEN]; 1853 u_char *optp = opts; 1854 1855 thoff = th->th_off << 2; 1856 cnt = thoff - sizeof(struct tcphdr); 1857 1858 if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt, 1859 NULL, NULL, af)) 1860 return (rewrite); 1861 1862 for (; cnt > 0; cnt -= optlen, optp += optlen) { 1863 opt = optp[0]; 1864 if (opt == TCPOPT_EOL) 1865 break; 1866 if (opt == TCPOPT_NOP) 1867 optlen = 1; 1868 else { 1869 if (cnt < 2) 1870 break; 1871 optlen = optp[1]; 1872 if (optlen < 2 || optlen > cnt) 1873 break; 1874 } 1875 switch (opt) { 1876 case TCPOPT_MAXSEG: 1877 mss = (u_int16_t *)(optp + 2); 1878 if ((ntohs(*mss)) > r->max_mss) { 1879 th->th_sum = pf_cksum_fixup(th->th_sum, 1880 *mss, htons(r->max_mss), 0); 1881 *mss = htons(r->max_mss); 1882 rewrite = 1; 1883 } 1884 break; 1885 default: 1886 break; 1887 } 1888 } 1889 1890 if (rewrite) 1891 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts); 1892 1893 return (rewrite); 1894 } 1895