1 /* $NetBSD: pf_norm.c,v 1.17 2007/12/11 11:08:21 lukem Exp $ */ 2 /* $OpenBSD: pf_norm.c,v 1.97 2004/09/21 16:59:12 aaron Exp $ */ 3 4 /* 5 * Copyright 2001 Niels Provos <provos@citi.umich.edu> 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __KERNEL_RCSID(0, "$NetBSD: pf_norm.c,v 1.17 2007/12/11 11:08:21 lukem Exp $"); 31 32 #ifdef _KERNEL_OPT 33 #include "opt_inet.h" 34 #endif 35 36 #include "pflog.h" 37 38 #include <sys/param.h> 39 #include <sys/systm.h> 40 #include <sys/mbuf.h> 41 #include <sys/filio.h> 42 #include <sys/fcntl.h> 43 #include <sys/socket.h> 44 #include <sys/kernel.h> 45 #include <sys/time.h> 46 #include <sys/pool.h> 47 48 #ifdef __OpenBSD__ 49 #include <dev/rndvar.h> 50 #else 51 #include <sys/rnd.h> 52 #endif 53 #include <net/if.h> 54 #include <net/if_types.h> 55 #include <net/bpf.h> 56 #include <net/route.h> 57 #include <net/if_pflog.h> 58 59 #include <netinet/in.h> 60 #include <netinet/in_var.h> 61 #include <netinet/in_systm.h> 62 #include <netinet/ip.h> 63 #include <netinet/ip_var.h> 64 #include <netinet/tcp.h> 65 #include <netinet/tcp_seq.h> 66 #include <netinet/udp.h> 67 #include <netinet/ip_icmp.h> 68 69 #ifdef INET6 70 #include <netinet/ip6.h> 71 #endif /* INET6 */ 72 73 #include <net/pfvar.h> 74 75 struct pf_frent { 76 LIST_ENTRY(pf_frent) fr_next; 77 struct ip *fr_ip; 78 struct mbuf *fr_m; 79 }; 80 81 struct pf_frcache { 82 LIST_ENTRY(pf_frcache) fr_next; 83 uint16_t fr_off; 84 uint16_t fr_end; 85 }; 86 87 #define PFFRAG_SEENLAST 0x0001 /* Seen the last fragment for this */ 88 #define PFFRAG_NOBUFFER 0x0002 /* Non-buffering fragment cache */ 89 #define PFFRAG_DROP 0x0004 /* Drop all fragments */ 90 #define BUFFER_FRAGMENTS(fr) (!((fr)->fr_flags & PFFRAG_NOBUFFER)) 91 92 struct pf_fragment { 93 RB_ENTRY(pf_fragment) fr_entry; 94 TAILQ_ENTRY(pf_fragment) frag_next; 95 struct in_addr fr_src; 96 struct in_addr fr_dst; 97 u_int8_t fr_p; /* protocol of this fragment */ 98 u_int8_t fr_flags; /* status flags */ 99 u_int16_t fr_id; /* fragment id for reassemble */ 100 u_int16_t fr_max; /* fragment data max */ 101 u_int32_t fr_timeout; 102 #define fr_queue fr_u.fru_queue 103 #define fr_cache fr_u.fru_cache 104 union { 105 LIST_HEAD(pf_fragq, pf_frent) fru_queue; /* buffering */ 106 LIST_HEAD(pf_cacheq, pf_frcache) fru_cache; /* non-buf */ 107 } fr_u; 108 }; 109 110 TAILQ_HEAD(pf_fragqueue, pf_fragment) pf_fragqueue; 111 TAILQ_HEAD(pf_cachequeue, pf_fragment) pf_cachequeue; 112 113 static __inline int pf_frag_compare(struct pf_fragment *, 114 struct pf_fragment *); 115 RB_HEAD(pf_frag_tree, pf_fragment) pf_frag_tree, pf_cache_tree; 116 RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 117 RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 118 119 /* Private prototypes */ 120 void pf_ip2key(struct pf_fragment *, struct ip *); 121 void pf_remove_fragment(struct pf_fragment *); 122 void pf_flush_fragments(void); 123 void pf_free_fragment(struct pf_fragment *); 124 struct pf_fragment *pf_find_fragment(struct ip *, struct pf_frag_tree *); 125 struct mbuf *pf_reassemble(struct mbuf **, struct pf_fragment **, 126 struct pf_frent *, int); 127 struct mbuf *pf_fragcache(struct mbuf **, struct ip*, 128 struct pf_fragment **, int, int, int *); 129 int pf_normalize_tcpopt(struct pf_rule *, struct mbuf *, 130 struct tcphdr *, int); 131 132 #define DPFPRINTF(x) do { \ 133 if (pf_status.debug >= PF_DEBUG_MISC) { \ 134 printf("%s: ", __func__); \ 135 printf x ; \ 136 } \ 137 } while(0) 138 139 /* Globals */ 140 struct pool pf_frent_pl, pf_frag_pl, pf_cache_pl, pf_cent_pl; 141 struct pool pf_state_scrub_pl; 142 int pf_nfrents, pf_ncache; 143 144 void 145 pf_normalize_init(void) 146 { 147 #ifdef __NetBSD__ 148 pool_init(&pf_frent_pl, sizeof(struct pf_frent), 0, 0, 0, "pffrent", 149 NULL, IPL_SOFTNET); 150 pool_init(&pf_frag_pl, sizeof(struct pf_fragment), 0, 0, 0, "pffrag", 151 NULL, IPL_SOFTNET); 152 pool_init(&pf_cache_pl, sizeof(struct pf_fragment), 0, 0, 0, 153 "pffrcache", NULL, IPL_SOFTNET); 154 pool_init(&pf_cent_pl, sizeof(struct pf_frcache), 0, 0, 0, "pffrcent", 155 NULL, IPL_SOFTNET); 156 pool_init(&pf_state_scrub_pl, sizeof(struct pf_state_scrub), 0, 0, 0, 157 "pfstscr", NULL, IPL_SOFTNET); 158 #else 159 pool_init(&pf_frent_pl, sizeof(struct pf_frent), 0, 0, 0, "pffrent", 160 NULL); 161 pool_init(&pf_frag_pl, sizeof(struct pf_fragment), 0, 0, 0, "pffrag", 162 NULL); 163 pool_init(&pf_cache_pl, sizeof(struct pf_fragment), 0, 0, 0, 164 "pffrcache", NULL); 165 pool_init(&pf_cent_pl, sizeof(struct pf_frcache), 0, 0, 0, "pffrcent", 166 NULL); 167 pool_init(&pf_state_scrub_pl, sizeof(struct pf_state_scrub), 0, 0, 0, 168 "pfstscr", NULL); 169 #endif 170 171 pool_sethiwat(&pf_frag_pl, PFFRAG_FRAG_HIWAT); 172 pool_sethardlimit(&pf_frent_pl, PFFRAG_FRENT_HIWAT, NULL, 0); 173 pool_sethardlimit(&pf_cache_pl, PFFRAG_FRCACHE_HIWAT, NULL, 0); 174 pool_sethardlimit(&pf_cent_pl, PFFRAG_FRCENT_HIWAT, NULL, 0); 175 176 TAILQ_INIT(&pf_fragqueue); 177 TAILQ_INIT(&pf_cachequeue); 178 } 179 180 #ifdef _LKM 181 void 182 pf_normalize_destroy(void) 183 { 184 pool_destroy(&pf_state_scrub_pl); 185 pool_destroy(&pf_cent_pl); 186 pool_destroy(&pf_cache_pl); 187 pool_destroy(&pf_frag_pl); 188 pool_destroy(&pf_frent_pl); 189 } 190 #endif 191 192 static __inline int 193 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b) 194 { 195 int diff; 196 197 if ((diff = a->fr_id - b->fr_id)) 198 return (diff); 199 else if ((diff = a->fr_p - b->fr_p)) 200 return (diff); 201 else if (a->fr_src.s_addr < b->fr_src.s_addr) 202 return (-1); 203 else if (a->fr_src.s_addr > b->fr_src.s_addr) 204 return (1); 205 else if (a->fr_dst.s_addr < b->fr_dst.s_addr) 206 return (-1); 207 else if (a->fr_dst.s_addr > b->fr_dst.s_addr) 208 return (1); 209 return (0); 210 } 211 212 void 213 pf_purge_expired_fragments(void) 214 { 215 struct pf_fragment *frag; 216 u_int32_t expire = time_second - 217 pf_default_rule.timeout[PFTM_FRAG]; 218 219 while ((frag = TAILQ_LAST(&pf_fragqueue, pf_fragqueue)) != NULL) { 220 KASSERT(BUFFER_FRAGMENTS(frag)); 221 if (frag->fr_timeout > expire) 222 break; 223 224 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); 225 pf_free_fragment(frag); 226 } 227 228 while ((frag = TAILQ_LAST(&pf_cachequeue, pf_cachequeue)) != NULL) { 229 KASSERT(!BUFFER_FRAGMENTS(frag)); 230 if (frag->fr_timeout > expire) 231 break; 232 233 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); 234 pf_free_fragment(frag); 235 KASSERT(TAILQ_EMPTY(&pf_cachequeue) || 236 TAILQ_LAST(&pf_cachequeue, pf_cachequeue) != frag); 237 } 238 } 239 240 /* 241 * Try to flush old fragments to make space for new ones 242 */ 243 244 void 245 pf_flush_fragments(void) 246 { 247 struct pf_fragment *frag; 248 int goal; 249 250 goal = pf_nfrents * 9 / 10; 251 DPFPRINTF(("trying to free > %d frents\n", 252 pf_nfrents - goal)); 253 while (goal < pf_nfrents) { 254 frag = TAILQ_LAST(&pf_fragqueue, pf_fragqueue); 255 if (frag == NULL) 256 break; 257 pf_free_fragment(frag); 258 } 259 260 261 goal = pf_ncache * 9 / 10; 262 DPFPRINTF(("trying to free > %d cache entries\n", 263 pf_ncache - goal)); 264 while (goal < pf_ncache) { 265 frag = TAILQ_LAST(&pf_cachequeue, pf_cachequeue); 266 if (frag == NULL) 267 break; 268 pf_free_fragment(frag); 269 } 270 } 271 272 /* Frees the fragments and all associated entries */ 273 274 void 275 pf_free_fragment(struct pf_fragment *frag) 276 { 277 struct pf_frent *frent; 278 struct pf_frcache *frcache; 279 280 /* Free all fragments */ 281 if (BUFFER_FRAGMENTS(frag)) { 282 for (frent = LIST_FIRST(&frag->fr_queue); frent; 283 frent = LIST_FIRST(&frag->fr_queue)) { 284 LIST_REMOVE(frent, fr_next); 285 286 m_freem(frent->fr_m); 287 pool_put(&pf_frent_pl, frent); 288 pf_nfrents--; 289 } 290 } else { 291 for (frcache = LIST_FIRST(&frag->fr_cache); frcache; 292 frcache = LIST_FIRST(&frag->fr_cache)) { 293 LIST_REMOVE(frcache, fr_next); 294 295 KASSERT(LIST_EMPTY(&frag->fr_cache) || 296 LIST_FIRST(&frag->fr_cache)->fr_off > 297 frcache->fr_end); 298 299 pool_put(&pf_cent_pl, frcache); 300 pf_ncache--; 301 } 302 } 303 304 pf_remove_fragment(frag); 305 } 306 307 void 308 pf_ip2key(struct pf_fragment *key, struct ip *ip) 309 { 310 key->fr_p = ip->ip_p; 311 key->fr_id = ip->ip_id; 312 key->fr_src.s_addr = ip->ip_src.s_addr; 313 key->fr_dst.s_addr = ip->ip_dst.s_addr; 314 } 315 316 struct pf_fragment * 317 pf_find_fragment(struct ip *ip, struct pf_frag_tree *tree) 318 { 319 struct pf_fragment key; 320 struct pf_fragment *frag; 321 322 pf_ip2key(&key, ip); 323 324 frag = RB_FIND(pf_frag_tree, tree, &key); 325 if (frag != NULL) { 326 /* XXX Are we sure we want to update the timeout? */ 327 frag->fr_timeout = time_second; 328 if (BUFFER_FRAGMENTS(frag)) { 329 TAILQ_REMOVE(&pf_fragqueue, frag, frag_next); 330 TAILQ_INSERT_HEAD(&pf_fragqueue, frag, frag_next); 331 } else { 332 TAILQ_REMOVE(&pf_cachequeue, frag, frag_next); 333 TAILQ_INSERT_HEAD(&pf_cachequeue, frag, frag_next); 334 } 335 } 336 337 return (frag); 338 } 339 340 /* Removes a fragment from the fragment queue and frees the fragment */ 341 342 void 343 pf_remove_fragment(struct pf_fragment *frag) 344 { 345 if (BUFFER_FRAGMENTS(frag)) { 346 RB_REMOVE(pf_frag_tree, &pf_frag_tree, frag); 347 TAILQ_REMOVE(&pf_fragqueue, frag, frag_next); 348 pool_put(&pf_frag_pl, frag); 349 } else { 350 RB_REMOVE(pf_frag_tree, &pf_cache_tree, frag); 351 TAILQ_REMOVE(&pf_cachequeue, frag, frag_next); 352 pool_put(&pf_cache_pl, frag); 353 } 354 } 355 356 #define FR_IP_OFF(fr) ((ntohs((fr)->fr_ip->ip_off) & IP_OFFMASK) << 3) 357 struct mbuf * 358 pf_reassemble(struct mbuf **m0, struct pf_fragment **frag, 359 struct pf_frent *frent, int mff) 360 { 361 struct mbuf *m = *m0, *m2; 362 struct pf_frent *frea, *next; 363 struct pf_frent *frep = NULL; 364 struct ip *ip = frent->fr_ip; 365 int hlen = ip->ip_hl << 2; 366 u_int16_t off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3; 367 u_int16_t ip_len = ntohs(ip->ip_len) - ip->ip_hl * 4; 368 u_int16_t max = ip_len + off; 369 370 KASSERT(*frag == NULL || BUFFER_FRAGMENTS(*frag)); 371 372 /* Strip off ip header */ 373 m->m_data += hlen; 374 m->m_len -= hlen; 375 376 /* Create a new reassembly queue for this packet */ 377 if (*frag == NULL) { 378 *frag = pool_get(&pf_frag_pl, PR_NOWAIT); 379 if (*frag == NULL) { 380 pf_flush_fragments(); 381 *frag = pool_get(&pf_frag_pl, PR_NOWAIT); 382 if (*frag == NULL) 383 goto drop_fragment; 384 } 385 386 (*frag)->fr_flags = 0; 387 (*frag)->fr_max = 0; 388 (*frag)->fr_src = frent->fr_ip->ip_src; 389 (*frag)->fr_dst = frent->fr_ip->ip_dst; 390 (*frag)->fr_p = frent->fr_ip->ip_p; 391 (*frag)->fr_id = frent->fr_ip->ip_id; 392 (*frag)->fr_timeout = time_second; 393 LIST_INIT(&(*frag)->fr_queue); 394 395 RB_INSERT(pf_frag_tree, &pf_frag_tree, *frag); 396 TAILQ_INSERT_HEAD(&pf_fragqueue, *frag, frag_next); 397 398 /* We do not have a previous fragment */ 399 frep = NULL; 400 goto insert; 401 } 402 403 /* 404 * Find a fragment after the current one: 405 * - off contains the real shifted offset. 406 */ 407 LIST_FOREACH(frea, &(*frag)->fr_queue, fr_next) { 408 if (FR_IP_OFF(frea) > off) 409 break; 410 frep = frea; 411 } 412 413 KASSERT(frep != NULL || frea != NULL); 414 415 if (frep != NULL && 416 FR_IP_OFF(frep) + ntohs(frep->fr_ip->ip_len) - frep->fr_ip->ip_hl * 417 4 > off) 418 { 419 u_int16_t precut; 420 421 precut = FR_IP_OFF(frep) + ntohs(frep->fr_ip->ip_len) - 422 frep->fr_ip->ip_hl * 4 - off; 423 if (precut >= ip_len) 424 goto drop_fragment; 425 m_adj(frent->fr_m, precut); 426 DPFPRINTF(("overlap -%d\n", precut)); 427 /* Enforce 8 byte boundaries */ 428 ip->ip_off = htons(ntohs(ip->ip_off) + (precut >> 3)); 429 off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3; 430 ip_len -= precut; 431 ip->ip_len = htons(ip_len); 432 } 433 434 for (; frea != NULL && ip_len + off > FR_IP_OFF(frea); 435 frea = next) 436 { 437 u_int16_t aftercut; 438 439 aftercut = ip_len + off - FR_IP_OFF(frea); 440 DPFPRINTF(("adjust overlap %d\n", aftercut)); 441 if (aftercut < ntohs(frea->fr_ip->ip_len) - frea->fr_ip->ip_hl 442 * 4) 443 { 444 frea->fr_ip->ip_len = 445 htons(ntohs(frea->fr_ip->ip_len) - aftercut); 446 frea->fr_ip->ip_off = htons(ntohs(frea->fr_ip->ip_off) + 447 (aftercut >> 3)); 448 m_adj(frea->fr_m, aftercut); 449 break; 450 } 451 452 /* This fragment is completely overlapped, loose it */ 453 next = LIST_NEXT(frea, fr_next); 454 m_freem(frea->fr_m); 455 LIST_REMOVE(frea, fr_next); 456 pool_put(&pf_frent_pl, frea); 457 pf_nfrents--; 458 } 459 460 insert: 461 /* Update maximum data size */ 462 if ((*frag)->fr_max < max) 463 (*frag)->fr_max = max; 464 /* This is the last segment */ 465 if (!mff) 466 (*frag)->fr_flags |= PFFRAG_SEENLAST; 467 468 if (frep == NULL) 469 LIST_INSERT_HEAD(&(*frag)->fr_queue, frent, fr_next); 470 else 471 LIST_INSERT_AFTER(frep, frent, fr_next); 472 473 /* Check if we are completely reassembled */ 474 if (!((*frag)->fr_flags & PFFRAG_SEENLAST)) 475 return (NULL); 476 477 /* Check if we have all the data */ 478 off = 0; 479 for (frep = LIST_FIRST(&(*frag)->fr_queue); frep; frep = next) { 480 next = LIST_NEXT(frep, fr_next); 481 482 off += ntohs(frep->fr_ip->ip_len) - frep->fr_ip->ip_hl * 4; 483 if (off < (*frag)->fr_max && 484 (next == NULL || FR_IP_OFF(next) != off)) 485 { 486 DPFPRINTF(("missing fragment at %d, next %d, max %d\n", 487 off, next == NULL ? -1 : FR_IP_OFF(next), 488 (*frag)->fr_max)); 489 return (NULL); 490 } 491 } 492 DPFPRINTF(("%d < %d?\n", off, (*frag)->fr_max)); 493 if (off < (*frag)->fr_max) 494 return (NULL); 495 496 /* We have all the data */ 497 frent = LIST_FIRST(&(*frag)->fr_queue); 498 KASSERT(frent != NULL); 499 if ((frent->fr_ip->ip_hl << 2) + off > IP_MAXPACKET) { 500 DPFPRINTF(("drop: too big: %d\n", off)); 501 pf_free_fragment(*frag); 502 *frag = NULL; 503 return (NULL); 504 } 505 next = LIST_NEXT(frent, fr_next); 506 507 /* Magic from ip_input */ 508 ip = frent->fr_ip; 509 m = frent->fr_m; 510 m2 = m->m_next; 511 m->m_next = NULL; 512 m_cat(m, m2); 513 pool_put(&pf_frent_pl, frent); 514 pf_nfrents--; 515 for (frent = next; frent != NULL; frent = next) { 516 next = LIST_NEXT(frent, fr_next); 517 518 m2 = frent->fr_m; 519 pool_put(&pf_frent_pl, frent); 520 pf_nfrents--; 521 m_cat(m, m2); 522 } 523 524 ip->ip_src = (*frag)->fr_src; 525 ip->ip_dst = (*frag)->fr_dst; 526 527 /* Remove from fragment queue */ 528 pf_remove_fragment(*frag); 529 *frag = NULL; 530 531 hlen = ip->ip_hl << 2; 532 ip->ip_len = htons(off + hlen); 533 m->m_len += hlen; 534 m->m_data -= hlen; 535 536 /* some debugging cruft by sklower, below, will go away soon */ 537 /* XXX this should be done elsewhere */ 538 if (m->m_flags & M_PKTHDR) { 539 int plen = 0; 540 for (m2 = m; m2; m2 = m2->m_next) 541 plen += m2->m_len; 542 m->m_pkthdr.len = plen; 543 #if defined(__NetBSD__) 544 m->m_pkthdr.csum_flags = 0; 545 #endif /* defined(__NetBSD__) */ 546 } 547 548 DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len))); 549 return (m); 550 551 drop_fragment: 552 /* Oops - fail safe - drop packet */ 553 pool_put(&pf_frent_pl, frent); 554 pf_nfrents--; 555 m_freem(m); 556 return (NULL); 557 } 558 559 struct mbuf * 560 pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff, 561 int drop, int *nomem) 562 { 563 struct mbuf *m = *m0; 564 struct pf_frcache *frp, *fra, *cur = NULL; 565 int ip_len = ntohs(h->ip_len) - (h->ip_hl << 2); 566 u_int16_t off = ntohs(h->ip_off) << 3; 567 u_int16_t max = ip_len + off; 568 int hosed = 0; 569 570 KASSERT(*frag == NULL || !BUFFER_FRAGMENTS(*frag)); 571 572 /* Create a new range queue for this packet */ 573 if (*frag == NULL) { 574 *frag = pool_get(&pf_cache_pl, PR_NOWAIT); 575 if (*frag == NULL) { 576 pf_flush_fragments(); 577 *frag = pool_get(&pf_cache_pl, PR_NOWAIT); 578 if (*frag == NULL) 579 goto no_mem; 580 } 581 582 /* Get an entry for the queue */ 583 cur = pool_get(&pf_cent_pl, PR_NOWAIT); 584 if (cur == NULL) { 585 pool_put(&pf_cache_pl, *frag); 586 *frag = NULL; 587 goto no_mem; 588 } 589 pf_ncache++; 590 591 (*frag)->fr_flags = PFFRAG_NOBUFFER; 592 (*frag)->fr_max = 0; 593 (*frag)->fr_src = h->ip_src; 594 (*frag)->fr_dst = h->ip_dst; 595 (*frag)->fr_p = h->ip_p; 596 (*frag)->fr_id = h->ip_id; 597 (*frag)->fr_timeout = time_second; 598 599 cur->fr_off = off; 600 cur->fr_end = max; 601 LIST_INIT(&(*frag)->fr_cache); 602 LIST_INSERT_HEAD(&(*frag)->fr_cache, cur, fr_next); 603 604 RB_INSERT(pf_frag_tree, &pf_cache_tree, *frag); 605 TAILQ_INSERT_HEAD(&pf_cachequeue, *frag, frag_next); 606 607 DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max)); 608 609 goto pass; 610 } 611 612 /* 613 * Find a fragment after the current one: 614 * - off contains the real shifted offset. 615 */ 616 frp = NULL; 617 LIST_FOREACH(fra, &(*frag)->fr_cache, fr_next) { 618 if (fra->fr_off > off) 619 break; 620 frp = fra; 621 } 622 623 KASSERT(frp != NULL || fra != NULL); 624 625 if (frp != NULL) { 626 int precut; 627 628 precut = frp->fr_end - off; 629 if (precut >= ip_len) { 630 /* Fragment is entirely a duplicate */ 631 DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n", 632 h->ip_id, frp->fr_off, frp->fr_end, off, max)); 633 goto drop_fragment; 634 } 635 if (precut == 0) { 636 /* They are adjacent. Fixup cache entry */ 637 DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n", 638 h->ip_id, frp->fr_off, frp->fr_end, off, max)); 639 frp->fr_end = max; 640 } else if (precut > 0) { 641 /* The first part of this payload overlaps with a 642 * fragment that has already been passed. 643 * Need to trim off the first part of the payload. 644 * But to do so easily, we need to create another 645 * mbuf to throw the original header into. 646 */ 647 648 DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n", 649 h->ip_id, precut, frp->fr_off, frp->fr_end, off, 650 max)); 651 652 off += precut; 653 max -= precut; 654 /* Update the previous frag to encompass this one */ 655 frp->fr_end = max; 656 657 if (!drop) { 658 /* XXX Optimization opportunity 659 * This is a very heavy way to trim the payload. 660 * we could do it much faster by diddling mbuf 661 * internals but that would be even less legible 662 * than this mbuf magic. For my next trick, 663 * I'll pull a rabbit out of my laptop. 664 */ 665 *m0 = m_copym2(m, 0, h->ip_hl << 2, M_NOWAIT); 666 if (*m0 == NULL) 667 goto no_mem; 668 KASSERT((*m0)->m_next == NULL); 669 m_adj(m, precut + (h->ip_hl << 2)); 670 m_cat(*m0, m); 671 m = *m0; 672 if (m->m_flags & M_PKTHDR) { 673 int plen = 0; 674 struct mbuf *t; 675 for (t = m; t; t = t->m_next) 676 plen += t->m_len; 677 m->m_pkthdr.len = plen; 678 } 679 680 681 h = mtod(m, struct ip *); 682 683 684 KASSERT((int)m->m_len == 685 ntohs(h->ip_len) - precut); 686 h->ip_off = htons(ntohs(h->ip_off) + 687 (precut >> 3)); 688 h->ip_len = htons(ntohs(h->ip_len) - precut); 689 } else { 690 hosed++; 691 } 692 } else { 693 /* There is a gap between fragments */ 694 695 DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n", 696 h->ip_id, -precut, frp->fr_off, frp->fr_end, off, 697 max)); 698 699 cur = pool_get(&pf_cent_pl, PR_NOWAIT); 700 if (cur == NULL) 701 goto no_mem; 702 pf_ncache++; 703 704 cur->fr_off = off; 705 cur->fr_end = max; 706 LIST_INSERT_AFTER(frp, cur, fr_next); 707 } 708 } 709 710 if (fra != NULL) { 711 int aftercut; 712 int merge = 0; 713 714 aftercut = max - fra->fr_off; 715 if (aftercut == 0) { 716 /* Adjacent fragments */ 717 DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n", 718 h->ip_id, off, max, fra->fr_off, fra->fr_end)); 719 fra->fr_off = off; 720 merge = 1; 721 } else if (aftercut > 0) { 722 /* Need to chop off the tail of this fragment */ 723 DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n", 724 h->ip_id, aftercut, off, max, fra->fr_off, 725 fra->fr_end)); 726 fra->fr_off = off; 727 max -= aftercut; 728 729 merge = 1; 730 731 if (!drop) { 732 m_adj(m, -aftercut); 733 if (m->m_flags & M_PKTHDR) { 734 int plen = 0; 735 struct mbuf *t; 736 for (t = m; t; t = t->m_next) 737 plen += t->m_len; 738 m->m_pkthdr.len = plen; 739 } 740 h = mtod(m, struct ip *); 741 KASSERT((int)m->m_len == 742 ntohs(h->ip_len) - aftercut); 743 h->ip_len = htons(ntohs(h->ip_len) - aftercut); 744 } else { 745 hosed++; 746 } 747 } else if (frp == NULL) { 748 /* There is a gap between fragments */ 749 DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n", 750 h->ip_id, -aftercut, off, max, fra->fr_off, 751 fra->fr_end)); 752 753 cur = pool_get(&pf_cent_pl, PR_NOWAIT); 754 if (cur == NULL) 755 goto no_mem; 756 pf_ncache++; 757 758 cur->fr_off = off; 759 cur->fr_end = max; 760 LIST_INSERT_BEFORE(fra, cur, fr_next); 761 } 762 763 764 /* Need to glue together two separate fragment descriptors */ 765 if (merge) { 766 if (cur && fra->fr_off <= cur->fr_end) { 767 /* Need to merge in a previous 'cur' */ 768 DPFPRINTF(("fragcache[%d]: adjacent(merge " 769 "%d-%d) %d-%d (%d-%d)\n", 770 h->ip_id, cur->fr_off, cur->fr_end, off, 771 max, fra->fr_off, fra->fr_end)); 772 fra->fr_off = cur->fr_off; 773 LIST_REMOVE(cur, fr_next); 774 pool_put(&pf_cent_pl, cur); 775 pf_ncache--; 776 cur = NULL; 777 778 } else if (frp && fra->fr_off <= frp->fr_end) { 779 /* Need to merge in a modified 'frp' */ 780 KASSERT(cur == NULL); 781 DPFPRINTF(("fragcache[%d]: adjacent(merge " 782 "%d-%d) %d-%d (%d-%d)\n", 783 h->ip_id, frp->fr_off, frp->fr_end, off, 784 max, fra->fr_off, fra->fr_end)); 785 fra->fr_off = frp->fr_off; 786 LIST_REMOVE(frp, fr_next); 787 pool_put(&pf_cent_pl, frp); 788 pf_ncache--; 789 frp = NULL; 790 791 } 792 } 793 } 794 795 if (hosed) { 796 /* 797 * We must keep tracking the overall fragment even when 798 * we're going to drop it anyway so that we know when to 799 * free the overall descriptor. Thus we drop the frag late. 800 */ 801 goto drop_fragment; 802 } 803 804 805 pass: 806 /* Update maximum data size */ 807 if ((*frag)->fr_max < max) 808 (*frag)->fr_max = max; 809 810 /* This is the last segment */ 811 if (!mff) 812 (*frag)->fr_flags |= PFFRAG_SEENLAST; 813 814 /* Check if we are completely reassembled */ 815 if (((*frag)->fr_flags & PFFRAG_SEENLAST) && 816 LIST_FIRST(&(*frag)->fr_cache)->fr_off == 0 && 817 LIST_FIRST(&(*frag)->fr_cache)->fr_end == (*frag)->fr_max) { 818 /* Remove from fragment queue */ 819 DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id, 820 (*frag)->fr_max)); 821 pf_free_fragment(*frag); 822 *frag = NULL; 823 } 824 825 return (m); 826 827 no_mem: 828 *nomem = 1; 829 830 /* Still need to pay attention to !IP_MF */ 831 if (!mff && *frag != NULL) 832 (*frag)->fr_flags |= PFFRAG_SEENLAST; 833 834 m_freem(m); 835 return (NULL); 836 837 drop_fragment: 838 839 /* Still need to pay attention to !IP_MF */ 840 if (!mff && *frag != NULL) 841 (*frag)->fr_flags |= PFFRAG_SEENLAST; 842 843 if (drop) { 844 /* This fragment has been deemed bad. Don't reass */ 845 if (((*frag)->fr_flags & PFFRAG_DROP) == 0) 846 DPFPRINTF(("fragcache[%d]: dropping overall fragment\n", 847 h->ip_id)); 848 (*frag)->fr_flags |= PFFRAG_DROP; 849 } 850 851 m_freem(m); 852 return (NULL); 853 } 854 855 int 856 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason, 857 struct pf_pdesc *pd) 858 { 859 struct mbuf *m = *m0; 860 struct pf_rule *r; 861 struct pf_frent *frent; 862 struct pf_fragment *frag = NULL; 863 struct ip *h = mtod(m, struct ip *); 864 int mff = (ntohs(h->ip_off) & IP_MF); 865 int hlen = h->ip_hl << 2; 866 u_int16_t fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3; 867 u_int16_t max; 868 int ip_len; 869 int ip_off; 870 871 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 872 while (r != NULL) { 873 r->evaluations++; 874 if (r->kif != NULL && 875 (r->kif != kif && r->kif != kif->pfik_parent) == !r->ifnot) 876 r = r->skip[PF_SKIP_IFP].ptr; 877 else if (r->direction && r->direction != dir) 878 r = r->skip[PF_SKIP_DIR].ptr; 879 else if (r->af && r->af != AF_INET) 880 r = r->skip[PF_SKIP_AF].ptr; 881 else if (r->proto && r->proto != h->ip_p) 882 r = r->skip[PF_SKIP_PROTO].ptr; 883 else if (PF_MISMATCHAW(&r->src.addr, 884 (struct pf_addr *)&h->ip_src.s_addr, AF_INET, r->src.neg)) 885 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 886 else if (PF_MISMATCHAW(&r->dst.addr, 887 (struct pf_addr *)&h->ip_dst.s_addr, AF_INET, r->dst.neg)) 888 r = r->skip[PF_SKIP_DST_ADDR].ptr; 889 else 890 break; 891 } 892 893 if (r == NULL) 894 return (PF_PASS); 895 else 896 r->packets++; 897 898 /* Check for illegal packets */ 899 if (hlen < (int)sizeof(struct ip)) 900 goto drop; 901 902 if (hlen > ntohs(h->ip_len)) 903 goto drop; 904 905 /* Clear IP_DF if the rule uses the no-df option */ 906 if (r->rule_flag & PFRULE_NODF) 907 h->ip_off &= htons(~IP_DF); 908 909 /* We will need other tests here */ 910 if (!fragoff && !mff) 911 goto no_fragment; 912 913 /* We're dealing with a fragment now. Don't allow fragments 914 * with IP_DF to enter the cache. If the flag was cleared by 915 * no-df above, fine. Otherwise drop it. 916 */ 917 if (h->ip_off & htons(IP_DF)) { 918 DPFPRINTF(("IP_DF\n")); 919 goto bad; 920 } 921 922 ip_len = ntohs(h->ip_len) - hlen; 923 ip_off = (ntohs(h->ip_off) & IP_OFFMASK) << 3; 924 925 /* All fragments are 8 byte aligned */ 926 if (mff && (ip_len & 0x7)) { 927 DPFPRINTF(("mff and %d\n", ip_len)); 928 goto bad; 929 } 930 931 /* Respect maximum length */ 932 if (fragoff + ip_len > IP_MAXPACKET) { 933 DPFPRINTF(("max packet %d\n", fragoff + ip_len)); 934 goto bad; 935 } 936 max = fragoff + ip_len; 937 938 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) { 939 /* Fully buffer all of the fragments */ 940 941 frag = pf_find_fragment(h, &pf_frag_tree); 942 943 /* Check if we saw the last fragment already */ 944 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 945 max > frag->fr_max) 946 goto bad; 947 948 /* Get an entry for the fragment queue */ 949 frent = pool_get(&pf_frent_pl, PR_NOWAIT); 950 if (frent == NULL) { 951 REASON_SET(reason, PFRES_MEMORY); 952 return (PF_DROP); 953 } 954 pf_nfrents++; 955 frent->fr_ip = h; 956 frent->fr_m = m; 957 958 /* Might return a completely reassembled mbuf, or NULL */ 959 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max)); 960 *m0 = m = pf_reassemble(m0, &frag, frent, mff); 961 962 if (m == NULL) 963 return (PF_DROP); 964 965 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP)) 966 goto drop; 967 968 h = mtod(m, struct ip *); 969 } else { 970 /* non-buffering fragment cache (drops or masks overlaps) */ 971 int nomem = 0; 972 973 if (dir == PF_OUT) { 974 if (m_tag_find(m, PACKET_TAG_PF_FRAGCACHE, NULL) != 975 NULL) { 976 /* Already passed the fragment cache in the 977 * input direction. If we continued, it would 978 * appear to be a dup and would be dropped. 979 */ 980 goto fragment_pass; 981 } 982 } 983 984 frag = pf_find_fragment(h, &pf_cache_tree); 985 986 /* Check if we saw the last fragment already */ 987 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 988 max > frag->fr_max) { 989 if (r->rule_flag & PFRULE_FRAGDROP) 990 frag->fr_flags |= PFFRAG_DROP; 991 goto bad; 992 } 993 994 *m0 = m = pf_fragcache(m0, h, &frag, mff, 995 (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem); 996 if (m == NULL) { 997 if (nomem) 998 goto no_mem; 999 goto drop; 1000 } 1001 1002 if (dir == PF_IN) { 1003 struct m_tag *mtag; 1004 1005 mtag = m_tag_get(PACKET_TAG_PF_FRAGCACHE, 0, M_NOWAIT); 1006 if (mtag == NULL) 1007 goto no_mem; 1008 m_tag_prepend(m, mtag); 1009 } 1010 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP)) 1011 goto drop; 1012 goto fragment_pass; 1013 } 1014 1015 no_fragment: 1016 /* At this point, only IP_DF is allowed in ip_off */ 1017 h->ip_off &= htons(IP_DF); 1018 1019 /* Enforce a minimum ttl, may cause endless packet loops */ 1020 if (r->min_ttl && h->ip_ttl < r->min_ttl) 1021 h->ip_ttl = r->min_ttl; 1022 1023 if (r->rule_flag & PFRULE_RANDOMID) { 1024 u_int16_t ip_id = h->ip_id; 1025 1026 h->ip_id = ip_randomid(); 1027 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0); 1028 } 1029 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) 1030 pd->flags |= PFDESC_IP_REAS; 1031 1032 return (PF_PASS); 1033 1034 fragment_pass: 1035 /* Enforce a minimum ttl, may cause endless packet loops */ 1036 if (r->min_ttl && h->ip_ttl < r->min_ttl) 1037 h->ip_ttl = r->min_ttl; 1038 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) 1039 pd->flags |= PFDESC_IP_REAS; 1040 return (PF_PASS); 1041 1042 no_mem: 1043 REASON_SET(reason, PFRES_MEMORY); 1044 if (r != NULL && r->log) 1045 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL); 1046 return (PF_DROP); 1047 1048 drop: 1049 REASON_SET(reason, PFRES_NORM); 1050 if (r != NULL && r->log) 1051 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL); 1052 return (PF_DROP); 1053 1054 bad: 1055 DPFPRINTF(("dropping bad fragment\n")); 1056 1057 /* Free associated fragments */ 1058 if (frag != NULL) 1059 pf_free_fragment(frag); 1060 1061 REASON_SET(reason, PFRES_FRAG); 1062 if (r != NULL && r->log) 1063 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL); 1064 1065 return (PF_DROP); 1066 } 1067 1068 #ifdef INET6 1069 int 1070 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif, 1071 u_short *reason, struct pf_pdesc *pd) 1072 { 1073 struct mbuf *m = *m0; 1074 struct pf_rule *r; 1075 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1076 int off; 1077 struct ip6_ext ext; 1078 struct ip6_opt opt; 1079 struct ip6_opt_jumbo jumbo; 1080 struct ip6_frag frag; 1081 u_int32_t jumbolen = 0, plen; 1082 u_int16_t fragoff = 0; 1083 int optend; 1084 int ooff; 1085 u_int8_t proto; 1086 int terminal; 1087 1088 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1089 while (r != NULL) { 1090 r->evaluations++; 1091 if (r->kif != NULL && 1092 (r->kif != kif && r->kif != kif->pfik_parent) == !r->ifnot) 1093 r = r->skip[PF_SKIP_IFP].ptr; 1094 else if (r->direction && r->direction != dir) 1095 r = r->skip[PF_SKIP_DIR].ptr; 1096 else if (r->af && r->af != AF_INET6) 1097 r = r->skip[PF_SKIP_AF].ptr; 1098 #if 0 /* header chain! */ 1099 else if (r->proto && r->proto != h->ip6_nxt) 1100 r = r->skip[PF_SKIP_PROTO].ptr; 1101 #endif 1102 else if (PF_MISMATCHAW(&r->src.addr, 1103 (struct pf_addr *)&h->ip6_src, AF_INET6, r->src.neg)) 1104 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1105 else if (PF_MISMATCHAW(&r->dst.addr, 1106 (struct pf_addr *)&h->ip6_dst, AF_INET6, r->dst.neg)) 1107 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1108 else 1109 break; 1110 } 1111 1112 if (r == NULL) 1113 return (PF_PASS); 1114 else 1115 r->packets++; 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); 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); 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); 1240 return (PF_DROP); 1241 } 1242 #endif /* INET6 */ 1243 1244 int 1245 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, 1246 int ipoff, 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 (r->kif != NULL && 1259 (r->kif != kif && r->kif != kif->pfik_parent) == !r->ifnot) 1260 r = r->skip[PF_SKIP_IFP].ptr; 1261 else if (r->direction && r->direction != dir) 1262 r = r->skip[PF_SKIP_DIR].ptr; 1263 else if (r->af && r->af != af) 1264 r = r->skip[PF_SKIP_AF].ptr; 1265 else if (r->proto && r->proto != pd->proto) 1266 r = r->skip[PF_SKIP_PROTO].ptr; 1267 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, r->src.neg)) 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, r->dst.neg)) 1273 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1274 else if (r->dst.port_op && !pf_match_port(r->dst.port_op, 1275 r->dst.port[0], r->dst.port[1], th->th_dport)) 1276 r = r->skip[PF_SKIP_DST_PORT].ptr; 1277 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match( 1278 pf_osfp_fingerprint(pd, m, off, th), 1279 r->os_fingerprint)) 1280 r = TAILQ_NEXT(r, entries); 1281 else { 1282 rm = r; 1283 break; 1284 } 1285 } 1286 1287 if (rm == NULL || rm->action == PF_NOSCRUB) 1288 return (PF_PASS); 1289 else 1290 r->packets++; 1291 1292 if (rm->rule_flag & PFRULE_REASSEMBLE_TCP) 1293 pd->flags |= PFDESC_TCP_NORM; 1294 1295 flags = th->th_flags; 1296 if (flags & TH_SYN) { 1297 /* Illegal packet */ 1298 if (flags & TH_RST) 1299 goto tcp_drop; 1300 1301 if (flags & TH_FIN) 1302 flags &= ~TH_FIN; 1303 } else { 1304 /* Illegal packet */ 1305 if (!(flags & (TH_ACK|TH_RST))) 1306 goto tcp_drop; 1307 } 1308 1309 if (!(flags & TH_ACK)) { 1310 /* These flags are only valid if ACK is set */ 1311 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG)) 1312 goto tcp_drop; 1313 } 1314 1315 /* Check for illegal header length */ 1316 if (th->th_off < (sizeof(struct tcphdr) >> 2)) 1317 goto tcp_drop; 1318 1319 /* If flags changed, or reserved data set, then adjust */ 1320 if (flags != th->th_flags || th->th_x2 != 0) { 1321 u_int16_t ov, nv; 1322 1323 ov = *(u_int16_t *)(&th->th_ack + 1); 1324 th->th_flags = flags; 1325 th->th_x2 = 0; 1326 nv = *(u_int16_t *)(&th->th_ack + 1); 1327 1328 th->th_sum = pf_cksum_fixup(th->th_sum, ov, nv, 0); 1329 rewrite = 1; 1330 } 1331 1332 /* Remove urgent pointer, if TH_URG is not set */ 1333 if (!(flags & TH_URG) && th->th_urp) { 1334 th->th_sum = pf_cksum_fixup(th->th_sum, th->th_urp, 0, 0); 1335 th->th_urp = 0; 1336 rewrite = 1; 1337 } 1338 1339 /* Process options */ 1340 if (r->max_mss && pf_normalize_tcpopt(r, m, th, off)) 1341 rewrite = 1; 1342 1343 /* copy back packet headers if we sanitized */ 1344 if (rewrite) 1345 m_copyback(m, off, sizeof(*th), th); 1346 1347 return (PF_PASS); 1348 1349 tcp_drop: 1350 REASON_SET(&reason, PFRES_NORM); 1351 if (rm != NULL && r->log) 1352 PFLOG_PACKET(kif, h, m, AF_INET, dir, reason, r, NULL, NULL); 1353 return (PF_DROP); 1354 } 1355 1356 int 1357 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd, 1358 struct tcphdr *th, struct pf_state_peer *src, 1359 struct pf_state_peer *dst) 1360 { 1361 u_int32_t tsval, tsecr; 1362 u_int8_t hdr[60]; 1363 u_int8_t *opt; 1364 1365 KASSERT(src->scrub == NULL); 1366 1367 src->scrub = pool_get(&pf_state_scrub_pl, PR_NOWAIT); 1368 if (src->scrub == NULL) 1369 return (1); 1370 bzero(src->scrub, sizeof(*src->scrub)); 1371 1372 switch (pd->af) { 1373 #ifdef INET 1374 case AF_INET: { 1375 struct ip *h = mtod(m, struct ip *); 1376 src->scrub->pfss_ttl = h->ip_ttl; 1377 break; 1378 } 1379 #endif /* INET */ 1380 #ifdef INET6 1381 case AF_INET6: { 1382 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1383 src->scrub->pfss_ttl = h->ip6_hlim; 1384 break; 1385 } 1386 #endif /* INET6 */ 1387 } 1388 1389 1390 /* 1391 * All normalizations below are only begun if we see the start of 1392 * the connections. They must all set an enabled bit in pfss_flags 1393 */ 1394 if ((th->th_flags & TH_SYN) == 0) 1395 return (0); 1396 1397 1398 if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub && 1399 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1400 /* Diddle with TCP options */ 1401 int hlen; 1402 opt = hdr + sizeof(struct tcphdr); 1403 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1404 while (hlen >= TCPOLEN_TIMESTAMP) { 1405 switch (*opt) { 1406 case TCPOPT_EOL: /* FALLTHROUGH */ 1407 case TCPOPT_NOP: 1408 opt++; 1409 hlen--; 1410 break; 1411 case TCPOPT_TIMESTAMP: 1412 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1413 src->scrub->pfss_flags |= 1414 PFSS_TIMESTAMP; 1415 src->scrub->pfss_ts_mod = 1416 htonl(arc4random()); 1417 1418 /* note PFSS_PAWS not set yet */ 1419 memcpy(&tsval, &opt[2], 1420 sizeof(u_int32_t)); 1421 memcpy(&tsecr, &opt[6], 1422 sizeof(u_int32_t)); 1423 src->scrub->pfss_tsval0 = ntohl(tsval); 1424 src->scrub->pfss_tsval = ntohl(tsval); 1425 src->scrub->pfss_tsecr = ntohl(tsecr); 1426 getmicrouptime(&src->scrub->pfss_last); 1427 } 1428 /* FALLTHROUGH */ 1429 default: 1430 hlen -= MAX(opt[1], 2); 1431 opt += MAX(opt[1], 2); 1432 break; 1433 } 1434 } 1435 } 1436 1437 return (0); 1438 } 1439 1440 void 1441 pf_normalize_tcp_cleanup(struct pf_state *state) 1442 { 1443 if (state->src.scrub) 1444 pool_put(&pf_state_scrub_pl, state->src.scrub); 1445 if (state->dst.scrub) 1446 pool_put(&pf_state_scrub_pl, state->dst.scrub); 1447 1448 /* Someday... flush the TCP segment reassembly descriptors. */ 1449 } 1450 1451 int 1452 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd, 1453 u_short *reason, struct tcphdr *th, struct pf_state *state, 1454 struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback) 1455 { 1456 struct timeval uptime; 1457 u_int32_t tsval, tsecr; 1458 u_int tsval_from_last; 1459 u_int8_t hdr[60]; 1460 u_int8_t *opt; 1461 int copyback = 0; 1462 int got_ts = 0; 1463 1464 KASSERT(src->scrub || dst->scrub); 1465 1466 /* 1467 * Enforce the minimum TTL seen for this connection. Negate a common 1468 * technique to evade an intrusion detection system and confuse 1469 * firewall state code. 1470 */ 1471 switch (pd->af) { 1472 #ifdef INET 1473 case AF_INET: { 1474 if (src->scrub) { 1475 struct ip *h = mtod(m, struct ip *); 1476 if (h->ip_ttl > src->scrub->pfss_ttl) 1477 src->scrub->pfss_ttl = h->ip_ttl; 1478 h->ip_ttl = src->scrub->pfss_ttl; 1479 } 1480 break; 1481 } 1482 #endif /* INET */ 1483 #ifdef INET6 1484 case AF_INET6: { 1485 if (src->scrub) { 1486 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1487 if (h->ip6_hlim > src->scrub->pfss_ttl) 1488 src->scrub->pfss_ttl = h->ip6_hlim; 1489 h->ip6_hlim = src->scrub->pfss_ttl; 1490 } 1491 break; 1492 } 1493 #endif /* INET6 */ 1494 } 1495 1496 if (th->th_off > (sizeof(struct tcphdr) >> 2) && 1497 ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) || 1498 (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) && 1499 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1500 /* Diddle with TCP options */ 1501 int hlen; 1502 opt = hdr + sizeof(struct tcphdr); 1503 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1504 while (hlen >= TCPOLEN_TIMESTAMP) { 1505 switch (*opt) { 1506 case TCPOPT_EOL: /* FALLTHROUGH */ 1507 case TCPOPT_NOP: 1508 opt++; 1509 hlen--; 1510 break; 1511 case TCPOPT_TIMESTAMP: 1512 /* Modulate the timestamps. Can be used for 1513 * NAT detection, OS uptime determination or 1514 * reboot detection. 1515 */ 1516 1517 if (got_ts) { 1518 /* Huh? Multiple timestamps!? */ 1519 if (pf_status.debug >= PF_DEBUG_MISC) { 1520 DPFPRINTF(("multiple TS??")); 1521 pf_print_state(state); 1522 printf("\n"); 1523 } 1524 REASON_SET(reason, PFRES_TS); 1525 return (PF_DROP); 1526 } 1527 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1528 memcpy(&tsval, &opt[2], 1529 sizeof(u_int32_t)); 1530 if (tsval && src->scrub && 1531 (src->scrub->pfss_flags & 1532 PFSS_TIMESTAMP)) { 1533 tsval = ntohl(tsval); 1534 pf_change_a(&opt[2], 1535 &th->th_sum, 1536 htonl(tsval + 1537 src->scrub->pfss_ts_mod), 1538 0); 1539 copyback = 1; 1540 } 1541 1542 /* Modulate TS reply iff valid (!0) */ 1543 memcpy(&tsecr, &opt[6], 1544 sizeof(u_int32_t)); 1545 if (tsecr && dst->scrub && 1546 (dst->scrub->pfss_flags & 1547 PFSS_TIMESTAMP)) { 1548 tsecr = ntohl(tsecr) 1549 - dst->scrub->pfss_ts_mod; 1550 pf_change_a(&opt[6], 1551 &th->th_sum, htonl(tsecr), 1552 0); 1553 copyback = 1; 1554 } 1555 got_ts = 1; 1556 } 1557 /* FALLTHROUGH */ 1558 default: 1559 hlen -= MAX(opt[1], 2); 1560 opt += MAX(opt[1], 2); 1561 break; 1562 } 1563 } 1564 if (copyback) { 1565 /* Copyback the options, caller copys back header */ 1566 *writeback = 1; 1567 m_copyback(m, off + sizeof(struct tcphdr), 1568 (th->th_off << 2) - sizeof(struct tcphdr), hdr + 1569 sizeof(struct tcphdr)); 1570 } 1571 } 1572 1573 1574 /* 1575 * Must invalidate PAWS checks on connections idle for too long. 1576 * The fastest allowed timestamp clock is 1ms. That turns out to 1577 * be about 24 days before it wraps. XXX Right now our lowerbound 1578 * TS echo check only works for the first 12 days of a connection 1579 * when the TS has exhausted half its 32bit space 1580 */ 1581 #define TS_MAX_IDLE (24*24*60*60) 1582 #define TS_MAX_CONN (12*24*60*60) /* XXX remove when better tsecr check */ 1583 1584 getmicrouptime(&uptime); 1585 if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) && 1586 (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE || 1587 time_second - state->creation > TS_MAX_CONN)) { 1588 if (pf_status.debug >= PF_DEBUG_MISC) { 1589 DPFPRINTF(("src idled out of PAWS\n")); 1590 pf_print_state(state); 1591 printf("\n"); 1592 } 1593 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS) 1594 | PFSS_PAWS_IDLED; 1595 } 1596 if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) && 1597 uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) { 1598 if (pf_status.debug >= PF_DEBUG_MISC) { 1599 DPFPRINTF(("dst idled out of PAWS\n")); 1600 pf_print_state(state); 1601 printf("\n"); 1602 } 1603 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS) 1604 | PFSS_PAWS_IDLED; 1605 } 1606 1607 if (got_ts && src->scrub && dst->scrub && 1608 (src->scrub->pfss_flags & PFSS_PAWS) && 1609 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1610 /* Validate that the timestamps are "in-window". 1611 * RFC1323 describes TCP Timestamp options that allow 1612 * measurement of RTT (round trip time) and PAWS 1613 * (protection against wrapped sequence numbers). PAWS 1614 * gives us a set of rules for rejecting packets on 1615 * long fat pipes (packets that were somehow delayed 1616 * in transit longer than the time it took to send the 1617 * full TCP sequence space of 4Gb). We can use these 1618 * rules and infer a few others that will let us treat 1619 * the 32bit timestamp and the 32bit echoed timestamp 1620 * as sequence numbers to prevent a blind attacker from 1621 * inserting packets into a connection. 1622 * 1623 * RFC1323 tells us: 1624 * - The timestamp on this packet must be greater than 1625 * or equal to the last value echoed by the other 1626 * endpoint. The RFC says those will be discarded 1627 * since it is a dup that has already been acked. 1628 * This gives us a lowerbound on the timestamp. 1629 * timestamp >= other last echoed timestamp 1630 * - The timestamp will be less than or equal to 1631 * the last timestamp plus the time between the 1632 * last packet and now. The RFC defines the max 1633 * clock rate as 1ms. We will allow clocks to be 1634 * up to 10% fast and will allow a total difference 1635 * or 30 seconds due to a route change. And this 1636 * gives us an upperbound on the timestamp. 1637 * timestamp <= last timestamp + max ticks 1638 * We have to be careful here. Windows will send an 1639 * initial timestamp of zero and then initialize it 1640 * to a random value after the 3whs; presumably to 1641 * avoid a DoS by having to call an expensive RNG 1642 * during a SYN flood. Proof MS has at least one 1643 * good security geek. 1644 * 1645 * - The TCP timestamp option must also echo the other 1646 * endpoints timestamp. The timestamp echoed is the 1647 * one carried on the earliest unacknowledged segment 1648 * on the left edge of the sequence window. The RFC 1649 * states that the host will reject any echoed 1650 * timestamps that were larger than any ever sent. 1651 * This gives us an upperbound on the TS echo. 1652 * tescr <= largest_tsval 1653 * - The lowerbound on the TS echo is a little more 1654 * tricky to determine. The other endpoint's echoed 1655 * values will not decrease. But there may be 1656 * network conditions that re-order packets and 1657 * cause our view of them to decrease. For now the 1658 * only lowerbound we can safely determine is that 1659 * the TS echo will never be less than the orginal 1660 * TS. XXX There is probably a better lowerbound. 1661 * Remove TS_MAX_CONN with better lowerbound check. 1662 * tescr >= other original TS 1663 * 1664 * It is also important to note that the fastest 1665 * timestamp clock of 1ms will wrap its 32bit space in 1666 * 24 days. So we just disable TS checking after 24 1667 * days of idle time. We actually must use a 12d 1668 * connection limit until we can come up with a better 1669 * lowerbound to the TS echo check. 1670 */ 1671 struct timeval delta_ts; 1672 int ts_fudge; 1673 1674 1675 /* 1676 * PFTM_TS_DIFF is how many seconds of leeway to allow 1677 * a host's timestamp. This can happen if the previous 1678 * packet got delayed in transit for much longer than 1679 * this packet. 1680 */ 1681 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0) 1682 ts_fudge = pf_default_rule.timeout[PFTM_TS_DIFF]; 1683 1684 1685 /* Calculate max ticks since the last timestamp */ 1686 #define TS_MAXFREQ 1100 /* RFC max TS freq of 1 kHz + 10% skew */ 1687 #define TS_MICROSECS 1000000 /* microseconds per second */ 1688 timersub(&uptime, &src->scrub->pfss_last, &delta_ts); 1689 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ; 1690 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ); 1691 1692 1693 if ((src->state >= TCPS_ESTABLISHED && 1694 dst->state >= TCPS_ESTABLISHED) && 1695 (SEQ_LT(tsval, dst->scrub->pfss_tsecr) || 1696 SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) || 1697 (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) || 1698 SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) { 1699 /* Bad RFC1323 implementation or an insertion attack. 1700 * 1701 * - Solaris 2.6 and 2.7 are known to send another ACK 1702 * after the FIN,FIN|ACK,ACK closing that carries 1703 * an old timestamp. 1704 */ 1705 1706 DPFPRINTF(("Timestamp failed %c%c%c%c\n", 1707 SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ', 1708 SEQ_GT(tsval, src->scrub->pfss_tsval + 1709 tsval_from_last) ? '1' : ' ', 1710 SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ', 1711 SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' ')); 1712 DPFPRINTF((" tsval: %" PRIu32 " tsecr: %" PRIu32 1713 " +ticks: %" PRIu32 " idle: %lus %lums\n", 1714 tsval, tsecr, tsval_from_last, delta_ts.tv_sec, 1715 delta_ts.tv_usec / 1000)); 1716 DPFPRINTF((" src->tsval: %" PRIu32 " tsecr: %" PRIu32 1717 "\n", 1718 src->scrub->pfss_tsval, src->scrub->pfss_tsecr)); 1719 DPFPRINTF((" dst->tsval: %" PRIu32 " tsecr: %" PRIu32 1720 " tsval0: %" PRIu32 "\n", 1721 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 immedietly 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) 1847 { 1848 u_int16_t *mss; 1849 int thoff; 1850 int opt, cnt, optlen = 0; 1851 int rewrite = 0; 1852 u_char *optp; 1853 1854 thoff = th->th_off << 2; 1855 cnt = thoff - sizeof(struct tcphdr); 1856 optp = mtod(m, u_char *) + off + sizeof(struct tcphdr); 1857 1858 for (; cnt > 0; cnt -= optlen, optp += optlen) { 1859 opt = optp[0]; 1860 if (opt == TCPOPT_EOL) 1861 break; 1862 if (opt == TCPOPT_NOP) 1863 optlen = 1; 1864 else { 1865 if (cnt < 2) 1866 break; 1867 optlen = optp[1]; 1868 if (optlen < 2 || optlen > cnt) 1869 break; 1870 } 1871 switch (opt) { 1872 case TCPOPT_MAXSEG: 1873 mss = (u_int16_t *)(optp + 2); 1874 if ((ntohs(*mss)) > r->max_mss) { 1875 th->th_sum = pf_cksum_fixup(th->th_sum, 1876 *mss, htons(r->max_mss), 0); 1877 *mss = htons(r->max_mss); 1878 rewrite = 1; 1879 } 1880 break; 1881 default: 1882 break; 1883 } 1884 } 1885 1886 return (rewrite); 1887 } 1888