1 /* $OpenBSD: pf_norm.c,v 1.113 2008/05/07 07:07:29 markus Exp $ */ 2 3 /* 4 * Copyright (c) 2010 The DragonFly Project. All rights reserved. 5 * 6 * Copyright 2001 Niels Provos <provos@citi.umich.edu> 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 */ 29 30 #include "opt_inet.h" 31 #include "opt_inet6.h" 32 33 #include <sys/param.h> 34 #include <sys/systm.h> 35 #include <sys/mbuf.h> 36 #include <sys/filio.h> 37 #include <sys/fcntl.h> 38 #include <sys/socket.h> 39 #include <sys/kernel.h> 40 #include <sys/time.h> 41 42 #include <net/if.h> 43 #include <net/if_var.h> 44 #include <net/if_types.h> 45 #include <net/bpf.h> 46 #include <net/route.h> 47 #include <net/pf/if_pflog.h> 48 49 #include <netinet/in.h> 50 #include <netinet/in_var.h> 51 #include <netinet/in_systm.h> 52 #include <netinet/ip.h> 53 #include <netinet/ip_var.h> 54 #include <netinet/tcp.h> 55 #include <netinet/tcp_seq.h> 56 #include <netinet/udp.h> 57 #include <netinet/ip_icmp.h> 58 59 #ifdef INET6 60 #include <netinet/ip6.h> 61 #endif /* INET6 */ 62 63 #include <net/pf/pfvar.h> 64 65 #define PFFRAG_SEENLAST 0x0001 /* Seen the last fragment for this */ 66 #define PFFRAG_NOBUFFER 0x0002 /* Non-buffering fragment cache */ 67 #define PFFRAG_DROP 0x0004 /* Drop all fragments */ 68 #define BUFFER_FRAGMENTS(fr) (!((fr)->fr_flags & PFFRAG_NOBUFFER)) 69 70 71 TAILQ_HEAD(pf_fragqueue, pf_fragment) pf_fragqueue[MAXCPU]; 72 TAILQ_HEAD(pf_cachequeue, pf_fragment) pf_cachequeue[MAXCPU]; 73 74 static __inline int pf_frag_compare(struct pf_fragment *, 75 struct pf_fragment *); 76 RB_HEAD(pf_frag_tree, pf_fragment) pf_frag_tree[MAXCPU], 77 pf_cache_tree[MAXCPU]; 78 RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 79 RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 80 81 /* Private prototypes */ 82 void pf_ip2key(struct pf_fragment *, struct ip *); 83 void pf_remove_fragment(struct pf_fragment *); 84 void pf_flush_fragments(void); 85 void pf_free_fragment(struct pf_fragment *); 86 struct pf_fragment *pf_find_fragment(struct ip *, struct pf_frag_tree *); 87 struct mbuf *pf_reassemble(struct mbuf **, struct pf_fragment **, 88 struct pf_frent *, int); 89 struct mbuf *pf_fragcache(struct mbuf **, struct ip*, 90 struct pf_fragment **, int, int, int *); 91 int pf_normalize_tcpopt(struct pf_rule *, struct mbuf *, 92 struct tcphdr *, int, sa_family_t); 93 94 #define DPFPRINTF(x) do { \ 95 if (pf_status.debug >= PF_DEBUG_MISC) { \ 96 kprintf("%s: ", __func__); \ 97 kprintf x ; \ 98 } \ 99 } while(0) 100 101 static MALLOC_DEFINE(M_PFFRAGPL, "pffrag", "pf fragment pool list"); 102 static MALLOC_DEFINE(M_PFCACHEPL, "pffrcache", "pf fragment cache pool list"); 103 static MALLOC_DEFINE(M_PFFRENTPL, "pffrent", "pf frent pool list"); 104 static MALLOC_DEFINE(M_PFCENTPL, "pffrcent", "pf fragment cent pool list"); 105 static MALLOC_DEFINE(M_PFSTATESCRUBPL, "pfstatescrub", "pf state scrub pool list"); 106 107 /* Globals */ 108 struct malloc_type *pf_frent_pl, *pf_frag_pl, *pf_cache_pl, *pf_cent_pl; 109 struct malloc_type *pf_state_scrub_pl; 110 int pf_nfrents, pf_ncache; 111 112 void 113 pf_normalize_init(void) 114 { 115 int n; 116 117 /* XXX 118 pool_sethiwat(&pf_frag_pl, PFFRAG_FRAG_HIWAT); 119 pool_sethardlimit(&pf_frent_pl, PFFRAG_FRENT_HIWAT, NULL, 0); 120 pool_sethardlimit(&pf_cache_pl, PFFRAG_FRCACHE_HIWAT, NULL, 0); 121 pool_sethardlimit(&pf_cent_pl, PFFRAG_FRCENT_HIWAT, NULL, 0); 122 */ 123 124 for (n = 0; n < MAXCPU; ++n) { 125 TAILQ_INIT(&pf_fragqueue[n]); 126 TAILQ_INIT(&pf_cachequeue[n]); 127 RB_INIT(&pf_frag_tree[n]); 128 RB_INIT(&pf_cache_tree[n]); 129 } 130 } 131 132 static __inline int 133 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b) 134 { 135 int diff; 136 137 if ((diff = a->fr_id - b->fr_id)) 138 return (diff); 139 else if ((diff = a->fr_p - b->fr_p)) 140 return (diff); 141 else if (a->fr_src.s_addr < b->fr_src.s_addr) 142 return (-1); 143 else if (a->fr_src.s_addr > b->fr_src.s_addr) 144 return (1); 145 else if (a->fr_dst.s_addr < b->fr_dst.s_addr) 146 return (-1); 147 else if (a->fr_dst.s_addr > b->fr_dst.s_addr) 148 return (1); 149 return (0); 150 } 151 152 void 153 pf_purge_expired_fragments(void) 154 { 155 struct pf_fragment *frag; 156 u_int32_t expire; 157 int cpu = mycpu->gd_cpuid; 158 159 expire = time_second - pf_default_rule.timeout[PFTM_FRAG]; 160 161 while ((frag = TAILQ_LAST(&pf_fragqueue[cpu], pf_fragqueue)) != NULL) { 162 KASSERT((BUFFER_FRAGMENTS(frag)), 163 ("BUFFER_FRAGMENTS(frag) == 0: %s", __func__)); 164 if (frag->fr_timeout > expire) 165 break; 166 167 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); 168 pf_free_fragment(frag); 169 } 170 171 while ((frag = TAILQ_LAST(&pf_cachequeue[cpu], pf_cachequeue)) != NULL) { 172 KASSERT((!BUFFER_FRAGMENTS(frag)), 173 ("BUFFER_FRAGMENTS(frag) != 0: %s", __func__)); 174 if (frag->fr_timeout > expire) 175 break; 176 177 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); 178 pf_free_fragment(frag); 179 KASSERT((TAILQ_EMPTY(&pf_cachequeue[cpu]) || 180 TAILQ_LAST(&pf_cachequeue[cpu], pf_cachequeue) != frag), 181 ("!(TAILQ_EMPTY() || TAILQ_LAST() == farg): %s", 182 __func__)); 183 } 184 } 185 186 /* 187 * Try to flush old fragments to make space for new ones 188 */ 189 190 void 191 pf_flush_fragments(void) 192 { 193 struct pf_fragment *frag; 194 int goal; 195 int cpu = mycpu->gd_cpuid; 196 197 goal = pf_nfrents * 9 / 10; 198 DPFPRINTF(("trying to free > %d frents\n", 199 pf_nfrents - goal)); 200 while (goal < pf_nfrents) { 201 frag = TAILQ_LAST(&pf_fragqueue[cpu], pf_fragqueue); 202 if (frag == NULL) 203 break; 204 pf_free_fragment(frag); 205 } 206 207 208 goal = pf_ncache * 9 / 10; 209 DPFPRINTF(("trying to free > %d cache entries\n", 210 pf_ncache - goal)); 211 while (goal < pf_ncache) { 212 frag = TAILQ_LAST(&pf_cachequeue[cpu], pf_cachequeue); 213 if (frag == NULL) 214 break; 215 pf_free_fragment(frag); 216 } 217 } 218 219 /* Frees the fragments and all associated entries */ 220 221 void 222 pf_free_fragment(struct pf_fragment *frag) 223 { 224 struct pf_frent *frent; 225 struct pf_frcache *frcache; 226 227 /* Free all fragments */ 228 if (BUFFER_FRAGMENTS(frag)) { 229 for (frent = LIST_FIRST(&frag->fr_queue); frent; 230 frent = LIST_FIRST(&frag->fr_queue)) { 231 LIST_REMOVE(frent, fr_next); 232 233 m_freem(frent->fr_m); 234 kfree(frent, M_PFFRENTPL); 235 pf_nfrents--; 236 } 237 } else { 238 for (frcache = LIST_FIRST(&frag->fr_cache); frcache; 239 frcache = LIST_FIRST(&frag->fr_cache)) { 240 LIST_REMOVE(frcache, fr_next); 241 242 KASSERT((LIST_EMPTY(&frag->fr_cache) || 243 LIST_FIRST(&frag->fr_cache)->fr_off > 244 frcache->fr_end), 245 ("! (LIST_EMPTY() || LIST_FIRST()->fr_off >" 246 " frcache->fr_end): %s", __func__)); 247 248 kfree(frcache, M_PFCENTPL); 249 pf_ncache--; 250 } 251 } 252 253 pf_remove_fragment(frag); 254 } 255 256 void 257 pf_ip2key(struct pf_fragment *key, struct ip *ip) 258 { 259 key->fr_p = ip->ip_p; 260 key->fr_id = ip->ip_id; 261 key->fr_src.s_addr = ip->ip_src.s_addr; 262 key->fr_dst.s_addr = ip->ip_dst.s_addr; 263 } 264 265 struct pf_fragment * 266 pf_find_fragment(struct ip *ip, struct pf_frag_tree *tree) 267 { 268 struct pf_fragment key; 269 struct pf_fragment *frag; 270 int cpu = mycpu->gd_cpuid; 271 272 pf_ip2key(&key, ip); 273 274 frag = RB_FIND(pf_frag_tree, tree, &key); 275 if (frag != NULL) { 276 /* XXX Are we sure we want to update the timeout? */ 277 frag->fr_timeout = time_second; 278 if (BUFFER_FRAGMENTS(frag)) { 279 TAILQ_REMOVE(&pf_fragqueue[cpu], frag, frag_next); 280 TAILQ_INSERT_HEAD(&pf_fragqueue[cpu], frag, frag_next); 281 } else { 282 TAILQ_REMOVE(&pf_cachequeue[cpu], frag, frag_next); 283 TAILQ_INSERT_HEAD(&pf_cachequeue[cpu], frag, frag_next); 284 } 285 } 286 287 return (frag); 288 } 289 290 /* Removes a fragment from the fragment queue and frees the fragment */ 291 292 void 293 pf_remove_fragment(struct pf_fragment *frag) 294 { 295 int cpu = mycpu->gd_cpuid; 296 297 if (BUFFER_FRAGMENTS(frag)) { 298 RB_REMOVE(pf_frag_tree, &pf_frag_tree[cpu], frag); 299 TAILQ_REMOVE(&pf_fragqueue[cpu], frag, frag_next); 300 kfree(frag, M_PFFRAGPL); 301 } else { 302 RB_REMOVE(pf_frag_tree, &pf_cache_tree[cpu], frag); 303 TAILQ_REMOVE(&pf_cachequeue[cpu], frag, frag_next); 304 kfree(frag, M_PFCACHEPL); 305 } 306 } 307 308 #define FR_IP_OFF(fr) (((fr)->fr_ip->ip_off & IP_OFFMASK) << 3) 309 struct mbuf * 310 pf_reassemble(struct mbuf **m0, struct pf_fragment **frag, 311 struct pf_frent *frent, int mff) 312 { 313 struct mbuf *m = *m0, *m2; 314 struct pf_frent *frea, *next; 315 struct pf_frent *frep = NULL; 316 struct ip *ip = frent->fr_ip; 317 int hlen = ip->ip_hl << 2; 318 u_int16_t off = (ip->ip_off & IP_OFFMASK) << 3; 319 u_int16_t ip_len = ip->ip_len - ip->ip_hl * 4; 320 u_int16_t max = ip_len + off; 321 int cpu = mycpu->gd_cpuid; 322 323 KASSERT((*frag == NULL || BUFFER_FRAGMENTS(*frag)), 324 ("! (*frag == NULL || BUFFER_FRAGMENTS(*frag)): %s", __func__)); 325 326 /* Strip off ip header */ 327 m->m_data += hlen; 328 m->m_len -= hlen; 329 330 /* Create a new reassembly queue for this packet */ 331 if (*frag == NULL) { 332 *frag = kmalloc(sizeof(struct pf_fragment), M_PFFRAGPL, M_NOWAIT); 333 if (*frag == NULL) { 334 pf_flush_fragments(); 335 *frag = kmalloc(sizeof(struct pf_fragment), M_PFFRAGPL, M_NOWAIT); 336 if (*frag == NULL) 337 goto drop_fragment; 338 } 339 340 (*frag)->fr_flags = 0; 341 (*frag)->fr_max = 0; 342 (*frag)->fr_src = frent->fr_ip->ip_src; 343 (*frag)->fr_dst = frent->fr_ip->ip_dst; 344 (*frag)->fr_p = frent->fr_ip->ip_p; 345 (*frag)->fr_id = frent->fr_ip->ip_id; 346 (*frag)->fr_timeout = time_second; 347 LIST_INIT(&(*frag)->fr_queue); 348 349 RB_INSERT(pf_frag_tree, &pf_frag_tree[cpu], *frag); 350 TAILQ_INSERT_HEAD(&pf_fragqueue[cpu], *frag, frag_next); 351 352 /* We do not have a previous fragment */ 353 frep = NULL; 354 goto insert; 355 } 356 357 /* 358 * Find a fragment after the current one: 359 * - off contains the real shifted offset. 360 */ 361 LIST_FOREACH(frea, &(*frag)->fr_queue, fr_next) { 362 if (FR_IP_OFF(frea) > off) 363 break; 364 frep = frea; 365 } 366 367 KASSERT((frep != NULL || frea != NULL), 368 ("!(frep != NULL || frea != NULL): %s", __func__)); 369 370 if (frep != NULL && 371 FR_IP_OFF(frep) + frep->fr_ip->ip_len - frep->fr_ip->ip_hl * 372 4 > off) 373 { 374 u_int16_t precut; 375 376 precut = FR_IP_OFF(frep) + frep->fr_ip->ip_len - 377 frep->fr_ip->ip_hl * 4 - off; 378 if (precut >= ip_len) 379 goto drop_fragment; 380 m_adj(frent->fr_m, precut); 381 DPFPRINTF(("overlap -%d\n", precut)); 382 /* Enforce 8 byte boundaries */ 383 ip->ip_off = ip->ip_off + (precut >> 3); 384 off = (ip->ip_off & IP_OFFMASK) << 3; 385 ip_len -= precut; 386 ip->ip_len = ip_len; 387 } 388 389 for (; frea != NULL && ip_len + off > FR_IP_OFF(frea); 390 frea = next) 391 { 392 u_int16_t aftercut; 393 394 aftercut = ip_len + off - FR_IP_OFF(frea); 395 DPFPRINTF(("adjust overlap %d\n", aftercut)); 396 if (aftercut < frea->fr_ip->ip_len - frea->fr_ip->ip_hl 397 * 4) 398 { 399 frea->fr_ip->ip_len = 400 frea->fr_ip->ip_len - aftercut; 401 frea->fr_ip->ip_off = frea->fr_ip->ip_off + 402 (aftercut >> 3); 403 m_adj(frea->fr_m, aftercut); 404 break; 405 } 406 407 /* This fragment is completely overlapped, lose it */ 408 next = LIST_NEXT(frea, fr_next); 409 m_freem(frea->fr_m); 410 LIST_REMOVE(frea, fr_next); 411 kfree(frea, M_PFFRENTPL); 412 pf_nfrents--; 413 } 414 415 insert: 416 /* Update maximum data size */ 417 if ((*frag)->fr_max < max) 418 (*frag)->fr_max = max; 419 /* This is the last segment */ 420 if (!mff) 421 (*frag)->fr_flags |= PFFRAG_SEENLAST; 422 423 if (frep == NULL) 424 LIST_INSERT_HEAD(&(*frag)->fr_queue, frent, fr_next); 425 else 426 LIST_INSERT_AFTER(frep, frent, fr_next); 427 428 /* Check if we are completely reassembled */ 429 if (!((*frag)->fr_flags & PFFRAG_SEENLAST)) 430 return (NULL); 431 432 /* Check if we have all the data */ 433 off = 0; 434 for (frep = LIST_FIRST(&(*frag)->fr_queue); frep; frep = next) { 435 next = LIST_NEXT(frep, fr_next); 436 437 off += frep->fr_ip->ip_len - frep->fr_ip->ip_hl * 4; 438 if (off < (*frag)->fr_max && 439 (next == NULL || FR_IP_OFF(next) != off)) 440 { 441 DPFPRINTF(("missing fragment at %d, next %d, max %d\n", 442 off, next == NULL ? -1 : FR_IP_OFF(next), 443 (*frag)->fr_max)); 444 return (NULL); 445 } 446 } 447 DPFPRINTF(("%d < %d?\n", off, (*frag)->fr_max)); 448 if (off < (*frag)->fr_max) 449 return (NULL); 450 451 /* We have all the data */ 452 frent = LIST_FIRST(&(*frag)->fr_queue); 453 KASSERT((frent != NULL), ("frent == NULL: %s", __func__)); 454 if ((frent->fr_ip->ip_hl << 2) + off > IP_MAXPACKET) { 455 DPFPRINTF(("drop: too big: %d\n", off)); 456 pf_free_fragment(*frag); 457 *frag = NULL; 458 return (NULL); 459 } 460 next = LIST_NEXT(frent, fr_next); 461 462 /* Magic from ip_input */ 463 ip = frent->fr_ip; 464 m = frent->fr_m; 465 m2 = m->m_next; 466 m->m_next = NULL; 467 m_cat(m, m2); 468 kfree(frent, M_PFFRENTPL); 469 pf_nfrents--; 470 for (frent = next; frent != NULL; frent = next) { 471 next = LIST_NEXT(frent, fr_next); 472 473 m2 = frent->fr_m; 474 kfree(frent, M_PFFRENTPL); 475 pf_nfrents--; 476 m_cat(m, m2); 477 } 478 479 ip->ip_src = (*frag)->fr_src; 480 ip->ip_dst = (*frag)->fr_dst; 481 482 /* Remove from fragment queue */ 483 pf_remove_fragment(*frag); 484 *frag = NULL; 485 486 hlen = ip->ip_hl << 2; 487 ip->ip_len = off + hlen; 488 m->m_len += hlen; 489 m->m_data -= hlen; 490 491 /* some debugging cruft by sklower, below, will go away soon */ 492 /* XXX this should be done elsewhere */ 493 if (m->m_flags & M_PKTHDR) { 494 int plen = 0; 495 for (m2 = m; m2; m2 = m2->m_next) 496 plen += m2->m_len; 497 m->m_pkthdr.len = plen; 498 } 499 500 DPFPRINTF(("complete: %p(%d)\n", m, ip->ip_len)); 501 return (m); 502 503 drop_fragment: 504 /* Oops - fail safe - drop packet */ 505 kfree(frent, M_PFFRENTPL); 506 pf_nfrents--; 507 m_freem(m); 508 return (NULL); 509 } 510 511 struct mbuf * 512 pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff, 513 int drop, int *nomem) 514 { 515 struct mbuf *m = *m0; 516 struct pf_frcache *frp, *fra, *cur = NULL; 517 int ip_len = h->ip_len - (h->ip_hl << 2); 518 u_int16_t off = h->ip_off << 3; 519 u_int16_t max = ip_len + off; 520 int hosed = 0; 521 int cpu = mycpu->gd_cpuid; 522 523 KASSERT((*frag == NULL || !BUFFER_FRAGMENTS(*frag)), 524 ("!(*frag == NULL || !BUFFER_FRAGMENTS(*frag)): %s", __func__)); 525 526 /* Create a new range queue for this packet */ 527 if (*frag == NULL) { 528 *frag = kmalloc(sizeof(struct pf_fragment), M_PFCACHEPL, M_NOWAIT); 529 if (*frag == NULL) { 530 pf_flush_fragments(); 531 *frag = kmalloc(sizeof(struct pf_fragment), M_PFCACHEPL, M_NOWAIT); 532 if (*frag == NULL) 533 goto no_mem; 534 } 535 536 /* Get an entry for the queue */ 537 cur = kmalloc(sizeof(struct pf_frcache), M_PFCENTPL, M_NOWAIT); 538 if (cur == NULL) { 539 kfree(*frag, M_PFCACHEPL); 540 *frag = NULL; 541 goto no_mem; 542 } 543 pf_ncache++; 544 545 (*frag)->fr_flags = PFFRAG_NOBUFFER; 546 (*frag)->fr_max = 0; 547 (*frag)->fr_src = h->ip_src; 548 (*frag)->fr_dst = h->ip_dst; 549 (*frag)->fr_p = h->ip_p; 550 (*frag)->fr_id = h->ip_id; 551 (*frag)->fr_timeout = time_second; 552 553 cur->fr_off = off; 554 cur->fr_end = max; 555 LIST_INIT(&(*frag)->fr_cache); 556 LIST_INSERT_HEAD(&(*frag)->fr_cache, cur, fr_next); 557 558 RB_INSERT(pf_frag_tree, &pf_cache_tree[cpu], *frag); 559 TAILQ_INSERT_HEAD(&pf_cachequeue[cpu], *frag, frag_next); 560 561 DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max)); 562 563 goto pass; 564 } 565 566 /* 567 * Find a fragment after the current one: 568 * - off contains the real shifted offset. 569 */ 570 frp = NULL; 571 LIST_FOREACH(fra, &(*frag)->fr_cache, fr_next) { 572 if (fra->fr_off > off) 573 break; 574 frp = fra; 575 } 576 577 KASSERT((frp != NULL || fra != NULL), 578 ("!(frp != NULL || fra != NULL): %s", __func__)); 579 580 if (frp != NULL) { 581 int precut; 582 583 precut = frp->fr_end - off; 584 if (precut >= ip_len) { 585 /* Fragment is entirely a duplicate */ 586 DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n", 587 h->ip_id, frp->fr_off, frp->fr_end, off, max)); 588 goto drop_fragment; 589 } 590 if (precut == 0) { 591 /* They are adjacent. Fixup cache entry */ 592 DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n", 593 h->ip_id, frp->fr_off, frp->fr_end, off, max)); 594 frp->fr_end = max; 595 } else if (precut > 0) { 596 /* The first part of this payload overlaps with a 597 * fragment that has already been passed. 598 * Need to trim off the first part of the payload. 599 * But to do so easily, we need to create another 600 * mbuf to throw the original header into. 601 */ 602 603 DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n", 604 h->ip_id, precut, frp->fr_off, frp->fr_end, off, 605 max)); 606 607 off += precut; 608 max -= precut; 609 /* Update the previous frag to encompass this one */ 610 frp->fr_end = max; 611 612 if (!drop) { 613 /* XXX Optimization opportunity 614 * This is a very heavy way to trim the payload. 615 * we could do it much faster by diddling mbuf 616 * internals but that would be even less legible 617 * than this mbuf magic. For my next trick, 618 * I'll pull a rabbit out of my laptop. 619 */ 620 *m0 = m_dup(m, M_NOWAIT); 621 /* From KAME Project : We have missed this! */ 622 m_adj(*m0, (h->ip_hl << 2) - 623 (*m0)->m_pkthdr.len); 624 if (*m0 == NULL) 625 goto no_mem; 626 KASSERT(((*m0)->m_next == NULL), 627 ("(*m0)->m_next != NULL: %s", 628 __func__)); 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 KASSERT(((int)m->m_len == 644 h->ip_len - precut), 645 ("m->m_len != h->ip_len - precut: %s", 646 __func__)); 647 h->ip_off = h->ip_off + 648 (precut >> 3); 649 h->ip_len = h->ip_len - precut; 650 } else { 651 hosed++; 652 } 653 } else { 654 /* There is a gap between fragments */ 655 656 DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n", 657 h->ip_id, -precut, frp->fr_off, frp->fr_end, off, 658 max)); 659 660 cur = kmalloc(sizeof(struct pf_frcache), M_PFCENTPL, M_NOWAIT); 661 if (cur == NULL) 662 goto no_mem; 663 pf_ncache++; 664 665 cur->fr_off = off; 666 cur->fr_end = max; 667 LIST_INSERT_AFTER(frp, cur, fr_next); 668 } 669 } 670 671 if (fra != NULL) { 672 int aftercut; 673 int merge = 0; 674 675 aftercut = max - fra->fr_off; 676 if (aftercut == 0) { 677 /* Adjacent fragments */ 678 DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n", 679 h->ip_id, off, max, fra->fr_off, fra->fr_end)); 680 fra->fr_off = off; 681 merge = 1; 682 } else if (aftercut > 0) { 683 /* Need to chop off the tail of this fragment */ 684 DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n", 685 h->ip_id, aftercut, off, max, fra->fr_off, 686 fra->fr_end)); 687 fra->fr_off = off; 688 max -= aftercut; 689 690 merge = 1; 691 692 if (!drop) { 693 m_adj(m, -aftercut); 694 if (m->m_flags & M_PKTHDR) { 695 int plen = 0; 696 struct mbuf *t; 697 for (t = m; t; t = t->m_next) 698 plen += t->m_len; 699 m->m_pkthdr.len = plen; 700 } 701 h = mtod(m, struct ip *); 702 KASSERT(((int)m->m_len == h->ip_len - aftercut), 703 ("m->m_len != h->ip_len - aftercut: %s", 704 __func__)); 705 h->ip_len = h->ip_len - aftercut; 706 } else { 707 hosed++; 708 } 709 } else if (frp == NULL) { 710 /* There is a gap between fragments */ 711 DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n", 712 h->ip_id, -aftercut, off, max, fra->fr_off, 713 fra->fr_end)); 714 715 cur = kmalloc(sizeof(struct pf_frcache), M_PFCENTPL, M_NOWAIT); 716 if (cur == NULL) 717 goto no_mem; 718 pf_ncache++; 719 720 cur->fr_off = off; 721 cur->fr_end = max; 722 LIST_INSERT_BEFORE(fra, cur, fr_next); 723 } 724 725 726 /* Need to glue together two separate fragment descriptors */ 727 if (merge) { 728 if (cur && fra->fr_off <= cur->fr_end) { 729 /* Need to merge in a previous 'cur' */ 730 DPFPRINTF(("fragcache[%d]: adjacent(merge " 731 "%d-%d) %d-%d (%d-%d)\n", 732 h->ip_id, cur->fr_off, cur->fr_end, off, 733 max, fra->fr_off, fra->fr_end)); 734 fra->fr_off = cur->fr_off; 735 LIST_REMOVE(cur, fr_next); 736 kfree(cur, M_PFCENTPL); 737 pf_ncache--; 738 cur = NULL; 739 740 } else if (frp && fra->fr_off <= frp->fr_end) { 741 /* Need to merge in a modified 'frp' */ 742 KASSERT((cur == NULL), ("cur != NULL: %s", 743 __func__)); 744 DPFPRINTF(("fragcache[%d]: adjacent(merge " 745 "%d-%d) %d-%d (%d-%d)\n", 746 h->ip_id, frp->fr_off, frp->fr_end, off, 747 max, fra->fr_off, fra->fr_end)); 748 fra->fr_off = frp->fr_off; 749 LIST_REMOVE(frp, fr_next); 750 kfree(frp, M_PFCENTPL); 751 pf_ncache--; 752 frp = NULL; 753 754 } 755 } 756 } 757 758 if (hosed) { 759 /* 760 * We must keep tracking the overall fragment even when 761 * we're going to drop it anyway so that we know when to 762 * free the overall descriptor. Thus we drop the frag late. 763 */ 764 goto drop_fragment; 765 } 766 767 768 pass: 769 /* Update maximum data size */ 770 if ((*frag)->fr_max < max) 771 (*frag)->fr_max = max; 772 773 /* This is the last segment */ 774 if (!mff) 775 (*frag)->fr_flags |= PFFRAG_SEENLAST; 776 777 /* Check if we are completely reassembled */ 778 if (((*frag)->fr_flags & PFFRAG_SEENLAST) && 779 LIST_FIRST(&(*frag)->fr_cache)->fr_off == 0 && 780 LIST_FIRST(&(*frag)->fr_cache)->fr_end == (*frag)->fr_max) { 781 /* Remove from fragment queue */ 782 DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id, 783 (*frag)->fr_max)); 784 pf_free_fragment(*frag); 785 *frag = NULL; 786 } 787 788 return (m); 789 790 no_mem: 791 *nomem = 1; 792 793 /* Still need to pay attention to !IP_MF */ 794 if (!mff && *frag != NULL) 795 (*frag)->fr_flags |= PFFRAG_SEENLAST; 796 797 m_freem(m); 798 return (NULL); 799 800 drop_fragment: 801 802 /* Still need to pay attention to !IP_MF */ 803 if (!mff && *frag != NULL) 804 (*frag)->fr_flags |= PFFRAG_SEENLAST; 805 806 if (drop) { 807 /* This fragment has been deemed bad. Don't reass */ 808 if (((*frag)->fr_flags & PFFRAG_DROP) == 0) 809 DPFPRINTF(("fragcache[%d]: dropping overall fragment\n", 810 h->ip_id)); 811 (*frag)->fr_flags |= PFFRAG_DROP; 812 } 813 814 m_freem(m); 815 return (NULL); 816 } 817 818 int 819 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason, 820 struct pf_pdesc *pd) 821 { 822 struct mbuf *m = *m0; 823 struct pf_rule *r; 824 struct pf_frent *frent; 825 struct pf_fragment *frag = NULL; 826 struct ip *h = mtod(m, struct ip *); 827 int mff = (h->ip_off & IP_MF); 828 int hlen = h->ip_hl << 2; 829 u_int16_t fragoff = (h->ip_off & IP_OFFMASK) << 3; 830 u_int16_t max; 831 int ip_len; 832 int tag = -1; 833 int cpu = mycpu->gd_cpuid; 834 835 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 836 while (r != NULL) { 837 r->evaluations++; 838 if (pfi_kif_match(r->kif, kif) == r->ifnot) 839 r = r->skip[PF_SKIP_IFP].ptr; 840 else if (r->direction && r->direction != dir) 841 r = r->skip[PF_SKIP_DIR].ptr; 842 else if (r->af && r->af != AF_INET) 843 r = r->skip[PF_SKIP_AF].ptr; 844 else if (r->proto && r->proto != h->ip_p) 845 r = r->skip[PF_SKIP_PROTO].ptr; 846 else if (PF_MISMATCHAW(&r->src.addr, 847 (struct pf_addr *)&h->ip_src.s_addr, AF_INET, 848 r->src.neg, kif)) 849 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 850 else if (PF_MISMATCHAW(&r->dst.addr, 851 (struct pf_addr *)&h->ip_dst.s_addr, AF_INET, 852 r->dst.neg, NULL)) 853 r = r->skip[PF_SKIP_DST_ADDR].ptr; 854 else if (r->match_tag && !pf_match_tag(m, r, &tag)) 855 r = TAILQ_NEXT(r, entries); 856 else 857 break; 858 } 859 860 if (r == NULL || r->action == PF_NOSCRUB) 861 return (PF_PASS); 862 else { 863 r->packets[dir == PF_OUT]++; 864 r->bytes[dir == PF_OUT] += pd->tot_len; 865 } 866 867 /* Check for illegal packets */ 868 if (hlen < (int)sizeof(struct ip)) 869 goto drop; 870 871 if (hlen > h->ip_len) 872 goto drop; 873 874 /* Clear IP_DF if the rule uses the no-df option */ 875 if (r->rule_flag & PFRULE_NODF && h->ip_off & IP_DF) { 876 u_int16_t ip_off = h->ip_off; 877 878 h->ip_off &= ~IP_DF; 879 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 880 } 881 882 /* We will need other tests here */ 883 if (!fragoff && !mff) 884 goto no_fragment; 885 886 /* A fragment; rehash required. */ 887 m->m_flags &= ~M_HASH; 888 889 /* We're dealing with a fragment now. Don't allow fragments 890 * with IP_DF to enter the cache. If the flag was cleared by 891 * no-df above, fine. Otherwise drop it. 892 */ 893 if (h->ip_off & IP_DF) { 894 DPFPRINTF(("IP_DF\n")); 895 goto bad; 896 } 897 898 ip_len = h->ip_len - hlen; 899 900 /* All fragments are 8 byte aligned */ 901 if (mff && (ip_len & 0x7)) { 902 DPFPRINTF(("mff and %d\n", ip_len)); 903 goto bad; 904 } 905 906 /* Respect maximum length */ 907 if (fragoff + ip_len > IP_MAXPACKET) { 908 DPFPRINTF(("max packet %d\n", fragoff + ip_len)); 909 goto bad; 910 } 911 max = fragoff + ip_len; 912 913 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) { 914 /* Fully buffer all of the fragments */ 915 916 frag = pf_find_fragment(h, &pf_frag_tree[cpu]); 917 918 /* Check if we saw the last fragment already */ 919 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 920 max > frag->fr_max) 921 goto bad; 922 923 /* Get an entry for the fragment queue */ 924 frent = kmalloc(sizeof(struct pf_frent), M_PFFRENTPL, M_NOWAIT); 925 if (frent == NULL) { 926 REASON_SET(reason, PFRES_MEMORY); 927 return (PF_DROP); 928 } 929 pf_nfrents++; 930 frent->fr_ip = h; 931 frent->fr_m = m; 932 933 /* Might return a completely reassembled mbuf, or NULL */ 934 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max)); 935 *m0 = m = pf_reassemble(m0, &frag, frent, mff); 936 937 if (m == NULL) 938 return (PF_DROP); 939 940 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP)) 941 goto drop; 942 943 h = mtod(m, struct ip *); 944 } else { 945 /* non-buffering fragment cache (drops or masks overlaps) */ 946 int nomem = 0; 947 948 if (dir == PF_OUT && m->m_pkthdr.pf.flags & PF_TAG_FRAGCACHE) { 949 /* 950 * Already passed the fragment cache in the 951 * input direction. If we continued, it would 952 * appear to be a dup and would be dropped. 953 */ 954 goto fragment_pass; 955 } 956 957 frag = pf_find_fragment(h, &pf_cache_tree[cpu]); 958 959 /* Check if we saw the last fragment already */ 960 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 961 max > frag->fr_max) { 962 if (r->rule_flag & PFRULE_FRAGDROP) 963 frag->fr_flags |= PFFRAG_DROP; 964 goto bad; 965 } 966 967 *m0 = m = pf_fragcache(m0, h, &frag, mff, 968 (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem); 969 if (m == NULL) { 970 if (nomem) 971 goto no_mem; 972 goto drop; 973 } 974 975 if (dir == PF_IN) 976 m->m_pkthdr.pf.flags |= PF_TAG_FRAGCACHE; 977 978 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP)) 979 goto drop; 980 goto fragment_pass; 981 } 982 983 no_fragment: 984 /* At this point, only IP_DF is allowed in ip_off */ 985 if (h->ip_off & ~IP_DF) { 986 u_int16_t ip_off = h->ip_off; 987 988 h->ip_off &= IP_DF; 989 h->ip_sum = pf_cksum_fixup(h->ip_sum, htons(ip_off), htons(h->ip_off), 0); 990 } 991 992 /* Enforce a minimum ttl, may cause endless packet loops */ 993 if (r->min_ttl && h->ip_ttl < r->min_ttl) { 994 u_int16_t ip_ttl = h->ip_ttl; 995 996 h->ip_ttl = r->min_ttl; 997 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0); 998 } 999 1000 /* Enforce tos */ 1001 if (r->rule_flag & PFRULE_SET_TOS) { 1002 u_int16_t ov, nv; 1003 1004 ov = *(u_int16_t *)h; 1005 h->ip_tos = r->set_tos; 1006 nv = *(u_int16_t *)h; 1007 1008 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0); 1009 } 1010 1011 if (r->rule_flag & PFRULE_RANDOMID) { 1012 u_int16_t ip_id = h->ip_id; 1013 1014 h->ip_id = ip_randomid(); 1015 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0); 1016 } 1017 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) 1018 pd->flags |= PFDESC_IP_REAS; 1019 1020 return (PF_PASS); 1021 1022 fragment_pass: 1023 /* Enforce a minimum ttl, may cause endless packet loops */ 1024 if (r->min_ttl && h->ip_ttl < r->min_ttl) { 1025 u_int16_t ip_ttl = h->ip_ttl; 1026 1027 h->ip_ttl = r->min_ttl; 1028 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0); 1029 } 1030 /* Enforce tos */ 1031 if (r->rule_flag & PFRULE_SET_TOS) { 1032 u_int16_t ov, nv; 1033 1034 ov = *(u_int16_t *)h; 1035 h->ip_tos = r->set_tos; 1036 nv = *(u_int16_t *)h; 1037 1038 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0); 1039 } 1040 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) 1041 pd->flags |= PFDESC_IP_REAS; 1042 return (PF_PASS); 1043 1044 no_mem: 1045 REASON_SET(reason, PFRES_MEMORY); 1046 if (r != NULL && r->log) 1047 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL, pd); 1048 return (PF_DROP); 1049 1050 drop: 1051 REASON_SET(reason, PFRES_NORM); 1052 if (r != NULL && r->log) 1053 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL, pd); 1054 return (PF_DROP); 1055 1056 bad: 1057 DPFPRINTF(("dropping bad fragment\n")); 1058 1059 /* Free associated fragments */ 1060 if (frag != NULL) 1061 pf_free_fragment(frag); 1062 1063 REASON_SET(reason, PFRES_FRAG); 1064 if (r != NULL && r->log) 1065 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL, pd); 1066 1067 return (PF_DROP); 1068 } 1069 1070 #ifdef INET6 1071 int 1072 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif, 1073 u_short *reason, struct pf_pdesc *pd) 1074 { 1075 struct mbuf *m = *m0; 1076 struct pf_rule *r; 1077 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1078 int off; 1079 struct ip6_ext ext; 1080 struct ip6_opt opt; 1081 struct ip6_opt_jumbo jumbo; 1082 struct ip6_frag frag; 1083 u_int32_t jumbolen = 0, plen; 1084 u_int16_t fragoff = 0; 1085 int optend; 1086 int ooff; 1087 u_int8_t proto; 1088 int terminal; 1089 1090 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1091 while (r != NULL) { 1092 r->evaluations++; 1093 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1094 r = r->skip[PF_SKIP_IFP].ptr; 1095 else if (r->direction && r->direction != dir) 1096 r = r->skip[PF_SKIP_DIR].ptr; 1097 else if (r->af && r->af != AF_INET6) 1098 r = r->skip[PF_SKIP_AF].ptr; 1099 #if 0 /* header chain! */ 1100 else if (r->proto && r->proto != h->ip6_nxt) 1101 r = r->skip[PF_SKIP_PROTO].ptr; 1102 #endif 1103 else if (PF_MISMATCHAW(&r->src.addr, 1104 (struct pf_addr *)&h->ip6_src, AF_INET6, 1105 r->src.neg, kif)) 1106 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1107 else if (PF_MISMATCHAW(&r->dst.addr, 1108 (struct pf_addr *)&h->ip6_dst, AF_INET6, 1109 r->dst.neg, NULL)) 1110 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1111 else 1112 break; 1113 } 1114 1115 if (r == NULL || r->action == PF_NOSCRUB) 1116 return (PF_PASS); 1117 else { 1118 r->packets[dir == PF_OUT]++; 1119 r->bytes[dir == PF_OUT] += pd->tot_len; 1120 } 1121 1122 /* Check for illegal packets */ 1123 if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len) 1124 goto drop; 1125 1126 off = sizeof(struct ip6_hdr); 1127 proto = h->ip6_nxt; 1128 terminal = 0; 1129 do { 1130 switch (proto) { 1131 case IPPROTO_FRAGMENT: 1132 goto fragment; 1133 break; 1134 case IPPROTO_AH: 1135 case IPPROTO_ROUTING: 1136 case IPPROTO_DSTOPTS: 1137 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1138 NULL, AF_INET6)) 1139 goto shortpkt; 1140 if (proto == IPPROTO_AH) 1141 off += (ext.ip6e_len + 2) * 4; 1142 else 1143 off += (ext.ip6e_len + 1) * 8; 1144 proto = ext.ip6e_nxt; 1145 break; 1146 case IPPROTO_HOPOPTS: 1147 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1148 NULL, AF_INET6)) 1149 goto shortpkt; 1150 optend = off + (ext.ip6e_len + 1) * 8; 1151 ooff = off + sizeof(ext); 1152 do { 1153 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type, 1154 sizeof(opt.ip6o_type), NULL, NULL, 1155 AF_INET6)) 1156 goto shortpkt; 1157 if (opt.ip6o_type == IP6OPT_PAD1) { 1158 ooff++; 1159 continue; 1160 } 1161 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt), 1162 NULL, NULL, AF_INET6)) 1163 goto shortpkt; 1164 if (ooff + sizeof(opt) + opt.ip6o_len > optend) 1165 goto drop; 1166 switch (opt.ip6o_type) { 1167 case IP6OPT_JUMBO: 1168 if (h->ip6_plen != 0) 1169 goto drop; 1170 if (!pf_pull_hdr(m, ooff, &jumbo, 1171 sizeof(jumbo), NULL, NULL, 1172 AF_INET6)) 1173 goto shortpkt; 1174 memcpy(&jumbolen, jumbo.ip6oj_jumbo_len, 1175 sizeof(jumbolen)); 1176 jumbolen = ntohl(jumbolen); 1177 if (jumbolen <= IPV6_MAXPACKET) 1178 goto drop; 1179 if (sizeof(struct ip6_hdr) + jumbolen != 1180 m->m_pkthdr.len) 1181 goto drop; 1182 break; 1183 default: 1184 break; 1185 } 1186 ooff += sizeof(opt) + opt.ip6o_len; 1187 } while (ooff < optend); 1188 1189 off = optend; 1190 proto = ext.ip6e_nxt; 1191 break; 1192 default: 1193 terminal = 1; 1194 break; 1195 } 1196 } while (!terminal); 1197 1198 /* jumbo payload option must be present, or plen > 0 */ 1199 if (ntohs(h->ip6_plen) == 0) 1200 plen = jumbolen; 1201 else 1202 plen = ntohs(h->ip6_plen); 1203 if (plen == 0) 1204 goto drop; 1205 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1206 goto shortpkt; 1207 1208 /* Enforce a minimum ttl, may cause endless packet loops */ 1209 if (r->min_ttl && h->ip6_hlim < r->min_ttl) 1210 h->ip6_hlim = r->min_ttl; 1211 1212 return (PF_PASS); 1213 1214 fragment: 1215 if (ntohs(h->ip6_plen) == 0 || jumbolen) 1216 goto drop; 1217 plen = ntohs(h->ip6_plen); 1218 1219 if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6)) 1220 goto shortpkt; 1221 fragoff = ntohs(frag.ip6f_offlg & IP6F_OFF_MASK); 1222 if (fragoff + (plen - off - sizeof(frag)) > IPV6_MAXPACKET) 1223 goto badfrag; 1224 1225 /* do something about it */ 1226 /* remember to set pd->flags |= PFDESC_IP_REAS */ 1227 return (PF_PASS); 1228 1229 shortpkt: 1230 REASON_SET(reason, PFRES_SHORT); 1231 if (r != NULL && r->log) 1232 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL, pd); 1233 return (PF_DROP); 1234 1235 drop: 1236 REASON_SET(reason, PFRES_NORM); 1237 if (r != NULL && r->log) 1238 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL, pd); 1239 return (PF_DROP); 1240 1241 badfrag: 1242 REASON_SET(reason, PFRES_FRAG); 1243 if (r != NULL && r->log) 1244 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL, pd); 1245 return (PF_DROP); 1246 } 1247 #endif /* INET6 */ 1248 1249 int 1250 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff, 1251 int off, void *h, struct pf_pdesc *pd) 1252 { 1253 struct pf_rule *r, *rm = NULL; 1254 struct tcphdr *th = pd->hdr.tcp; 1255 int rewrite = 0; 1256 u_short reason; 1257 u_int8_t flags; 1258 sa_family_t af = pd->af; 1259 1260 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1261 while (r != NULL) { 1262 r->evaluations++; 1263 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1264 r = r->skip[PF_SKIP_IFP].ptr; 1265 else if (r->direction && r->direction != dir) 1266 r = r->skip[PF_SKIP_DIR].ptr; 1267 else if (r->af && r->af != af) 1268 r = r->skip[PF_SKIP_AF].ptr; 1269 else if (r->proto && r->proto != pd->proto) 1270 r = r->skip[PF_SKIP_PROTO].ptr; 1271 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, 1272 r->src.neg, kif)) 1273 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1274 else if (r->src.port_op && !pf_match_port(r->src.port_op, 1275 r->src.port[0], r->src.port[1], th->th_sport)) 1276 r = r->skip[PF_SKIP_SRC_PORT].ptr; 1277 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, 1278 r->dst.neg, NULL)) 1279 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1280 else if (r->dst.port_op && !pf_match_port(r->dst.port_op, 1281 r->dst.port[0], r->dst.port[1], th->th_dport)) 1282 r = r->skip[PF_SKIP_DST_PORT].ptr; 1283 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match( 1284 pf_osfp_fingerprint(pd, m, off, th), 1285 r->os_fingerprint)) 1286 r = TAILQ_NEXT(r, entries); 1287 else { 1288 rm = r; 1289 break; 1290 } 1291 } 1292 1293 if (rm == NULL || rm->action == PF_NOSCRUB) 1294 return (PF_PASS); 1295 else { 1296 r->packets[dir == PF_OUT]++; 1297 r->bytes[dir == PF_OUT] += pd->tot_len; 1298 } 1299 1300 if (rm->rule_flag & PFRULE_REASSEMBLE_TCP) 1301 pd->flags |= PFDESC_TCP_NORM; 1302 1303 flags = th->th_flags; 1304 if (flags & TH_SYN) { 1305 /* Illegal packet */ 1306 if (flags & TH_RST) 1307 goto tcp_drop; 1308 1309 if (flags & TH_FIN) 1310 flags &= ~TH_FIN; 1311 } else { 1312 /* Illegal packet */ 1313 if (!(flags & (TH_ACK|TH_RST))) 1314 goto tcp_drop; 1315 } 1316 1317 if (!(flags & TH_ACK)) { 1318 /* These flags are only valid if ACK is set */ 1319 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG)) 1320 goto tcp_drop; 1321 } 1322 1323 /* Check for illegal header length */ 1324 if (th->th_off < (sizeof(struct tcphdr) >> 2)) 1325 goto tcp_drop; 1326 1327 /* If flags changed, or reserved data set, then adjust */ 1328 if (flags != th->th_flags || th->th_x2 != 0) { 1329 u_int16_t ov, nv; 1330 1331 ov = *(u_int16_t *)(&th->th_ack + 1); 1332 th->th_flags = flags; 1333 th->th_x2 = 0; 1334 nv = *(u_int16_t *)(&th->th_ack + 1); 1335 1336 th->th_sum = pf_cksum_fixup(th->th_sum, ov, nv, 0); 1337 rewrite = 1; 1338 } 1339 1340 /* Remove urgent pointer, if TH_URG is not set */ 1341 if (!(flags & TH_URG) && th->th_urp) { 1342 th->th_sum = pf_cksum_fixup(th->th_sum, th->th_urp, 0, 0); 1343 th->th_urp = 0; 1344 rewrite = 1; 1345 } 1346 1347 /* Process options */ 1348 if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af)) 1349 rewrite = 1; 1350 1351 /* copy back packet headers if we sanitized */ 1352 if (rewrite) 1353 m_copyback(m, off, sizeof(*th), (caddr_t)th); 1354 1355 return (PF_PASS); 1356 1357 tcp_drop: 1358 REASON_SET(&reason, PFRES_NORM); 1359 if (rm != NULL && r->log) 1360 PFLOG_PACKET(kif, h, m, AF_INET, dir, reason, r, NULL, NULL, pd); 1361 return (PF_DROP); 1362 } 1363 1364 int 1365 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd, 1366 struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst) 1367 { 1368 u_int32_t tsval, tsecr; 1369 u_int8_t hdr[60]; 1370 u_int8_t *opt; 1371 1372 KASSERT((src->scrub == NULL), 1373 ("pf_normalize_tcp_init: src->scrub != NULL")); 1374 1375 src->scrub = kmalloc(sizeof(struct pf_state_scrub), M_PFSTATESCRUBPL, 1376 M_NOWAIT | M_ZERO); 1377 if (src->scrub == NULL) 1378 return (1); 1379 1380 switch (pd->af) { 1381 #ifdef INET 1382 case AF_INET: { 1383 struct ip *h = mtod(m, struct ip *); 1384 src->scrub->pfss_ttl = h->ip_ttl; 1385 break; 1386 } 1387 #endif /* INET */ 1388 #ifdef INET6 1389 case AF_INET6: { 1390 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1391 src->scrub->pfss_ttl = h->ip6_hlim; 1392 break; 1393 } 1394 #endif /* INET6 */ 1395 } 1396 1397 1398 /* 1399 * All normalizations below are only begun if we see the start of 1400 * the connections. They must all set an enabled bit in pfss_flags 1401 */ 1402 if ((th->th_flags & TH_SYN) == 0) 1403 return (0); 1404 1405 1406 if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub && 1407 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1408 /* Diddle with TCP options */ 1409 int hlen; 1410 opt = hdr + sizeof(struct tcphdr); 1411 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1412 while (hlen >= TCPOLEN_TIMESTAMP) { 1413 switch (*opt) { 1414 case TCPOPT_EOL: /* FALLTHROUGH */ 1415 case TCPOPT_NOP: 1416 opt++; 1417 hlen--; 1418 break; 1419 case TCPOPT_TIMESTAMP: 1420 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1421 src->scrub->pfss_flags |= 1422 PFSS_TIMESTAMP; 1423 src->scrub->pfss_ts_mod = karc4random(); 1424 1425 /* note PFSS_PAWS not set yet */ 1426 memcpy(&tsval, &opt[2], 1427 sizeof(u_int32_t)); 1428 memcpy(&tsecr, &opt[6], 1429 sizeof(u_int32_t)); 1430 src->scrub->pfss_tsval0 = ntohl(tsval); 1431 src->scrub->pfss_tsval = ntohl(tsval); 1432 src->scrub->pfss_tsecr = ntohl(tsecr); 1433 getmicrouptime(&src->scrub->pfss_last); 1434 } 1435 /* FALLTHROUGH */ 1436 default: 1437 hlen -= MAX(opt[1], 2); 1438 opt += MAX(opt[1], 2); 1439 break; 1440 } 1441 } 1442 } 1443 1444 return (0); 1445 } 1446 1447 void 1448 pf_normalize_tcp_cleanup(struct pf_state *state) 1449 { 1450 if (state->src.scrub) 1451 kfree(state->src.scrub, M_PFSTATESCRUBPL); 1452 if (state->dst.scrub) 1453 kfree(state->dst.scrub, M_PFSTATESCRUBPL); 1454 1455 /* Someday... flush the TCP segment reassembly descriptors. */ 1456 } 1457 1458 int 1459 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd, 1460 u_short *reason, struct tcphdr *th, struct pf_state *state, 1461 struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback) 1462 { 1463 struct timeval uptime; 1464 u_int32_t tsval, tsecr; 1465 u_int tsval_from_last; 1466 u_int8_t hdr[60]; 1467 u_int8_t *opt; 1468 int copyback = 0; 1469 int got_ts = 0; 1470 1471 KASSERT((src->scrub || dst->scrub), 1472 ("pf_normalize_tcp_statefull: src->scrub && dst->scrub!")); 1473 1474 tsval = 0; /* avoid gcc complaint */ 1475 tsecr = 0; /* avoid gcc complaint */ 1476 1477 /* 1478 * Enforce the minimum TTL seen for this connection. Negate a common 1479 * technique to evade an intrusion detection system and confuse 1480 * firewall state code. 1481 */ 1482 switch (pd->af) { 1483 #ifdef INET 1484 case AF_INET: { 1485 if (src->scrub) { 1486 struct ip *h = mtod(m, struct ip *); 1487 if (h->ip_ttl > src->scrub->pfss_ttl) 1488 src->scrub->pfss_ttl = h->ip_ttl; 1489 h->ip_ttl = src->scrub->pfss_ttl; 1490 } 1491 break; 1492 } 1493 #endif /* INET */ 1494 #ifdef INET6 1495 case AF_INET6: { 1496 if (src->scrub) { 1497 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1498 if (h->ip6_hlim > src->scrub->pfss_ttl) 1499 src->scrub->pfss_ttl = h->ip6_hlim; 1500 h->ip6_hlim = src->scrub->pfss_ttl; 1501 } 1502 break; 1503 } 1504 #endif /* INET6 */ 1505 } 1506 1507 if (th->th_off > (sizeof(struct tcphdr) >> 2) && 1508 ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) || 1509 (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) && 1510 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1511 /* Diddle with TCP options */ 1512 int hlen; 1513 opt = hdr + sizeof(struct tcphdr); 1514 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1515 while (hlen >= TCPOLEN_TIMESTAMP) { 1516 switch (*opt) { 1517 case TCPOPT_EOL: /* FALLTHROUGH */ 1518 case TCPOPT_NOP: 1519 opt++; 1520 hlen--; 1521 break; 1522 case TCPOPT_TIMESTAMP: 1523 /* Modulate the timestamps. Can be used for 1524 * NAT detection, OS uptime determination or 1525 * reboot detection. 1526 */ 1527 1528 if (got_ts) { 1529 /* Huh? Multiple timestamps!? */ 1530 if (pf_status.debug >= PF_DEBUG_MISC) { 1531 DPFPRINTF(("multiple TS??")); 1532 pf_print_state(state); 1533 kprintf("\n"); 1534 } 1535 REASON_SET(reason, PFRES_TS); 1536 return (PF_DROP); 1537 } 1538 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1539 memcpy(&tsval, &opt[2], 1540 sizeof(u_int32_t)); 1541 if (tsval && src->scrub && 1542 (src->scrub->pfss_flags & 1543 PFSS_TIMESTAMP)) { 1544 tsval = ntohl(tsval); 1545 pf_change_a(&opt[2], 1546 &th->th_sum, 1547 htonl(tsval + 1548 src->scrub->pfss_ts_mod), 1549 0); 1550 copyback = 1; 1551 } 1552 1553 /* Modulate TS reply iff valid (!0) */ 1554 memcpy(&tsecr, &opt[6], 1555 sizeof(u_int32_t)); 1556 if (tsecr && dst->scrub && 1557 (dst->scrub->pfss_flags & 1558 PFSS_TIMESTAMP)) { 1559 tsecr = ntohl(tsecr) 1560 - dst->scrub->pfss_ts_mod; 1561 pf_change_a(&opt[6], 1562 &th->th_sum, htonl(tsecr), 1563 0); 1564 copyback = 1; 1565 } 1566 got_ts = 1; 1567 } 1568 /* FALLTHROUGH */ 1569 default: 1570 hlen -= MAX(opt[1], 2); 1571 opt += MAX(opt[1], 2); 1572 break; 1573 } 1574 } 1575 if (copyback) { 1576 /* Copyback the options, caller copys back header */ 1577 *writeback = 1; 1578 m_copyback(m, off + sizeof(struct tcphdr), 1579 (th->th_off << 2) - sizeof(struct tcphdr), hdr + 1580 sizeof(struct tcphdr)); 1581 } 1582 } 1583 1584 1585 /* 1586 * Must invalidate PAWS checks on connections idle for too long. 1587 * The fastest allowed timestamp clock is 1ms. That turns out to 1588 * be about 24 days before it wraps. XXX Right now our lowerbound 1589 * TS echo check only works for the first 12 days of a connection 1590 * when the TS has exhausted half its 32bit space 1591 */ 1592 #define TS_MAX_IDLE (24*24*60*60) 1593 #define TS_MAX_CONN (12*24*60*60) /* XXX remove when better tsecr check */ 1594 1595 getmicrouptime(&uptime); 1596 if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) && 1597 (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE || 1598 time_second - state->creation > TS_MAX_CONN)) { 1599 if (pf_status.debug >= PF_DEBUG_MISC) { 1600 DPFPRINTF(("src idled out of PAWS\n")); 1601 pf_print_state(state); 1602 kprintf("\n"); 1603 } 1604 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS) 1605 | PFSS_PAWS_IDLED; 1606 } 1607 if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) && 1608 uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) { 1609 if (pf_status.debug >= PF_DEBUG_MISC) { 1610 DPFPRINTF(("dst idled out of PAWS\n")); 1611 pf_print_state(state); 1612 kprintf("\n"); 1613 } 1614 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS) 1615 | PFSS_PAWS_IDLED; 1616 } 1617 1618 if (got_ts && src->scrub && dst->scrub && 1619 (src->scrub->pfss_flags & PFSS_PAWS) && 1620 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1621 /* Validate that the timestamps are "in-window". 1622 * RFC1323 describes TCP Timestamp options that allow 1623 * measurement of RTT (round trip time) and PAWS 1624 * (protection against wrapped sequence numbers). PAWS 1625 * gives us a set of rules for rejecting packets on 1626 * long fat pipes (packets that were somehow delayed 1627 * in transit longer than the time it took to send the 1628 * full TCP sequence space of 4Gb). We can use these 1629 * rules and infer a few others that will let us treat 1630 * the 32bit timestamp and the 32bit echoed timestamp 1631 * as sequence numbers to prevent a blind attacker from 1632 * inserting packets into a connection. 1633 * 1634 * RFC1323 tells us: 1635 * - The timestamp on this packet must be greater than 1636 * or equal to the last value echoed by the other 1637 * endpoint. The RFC says those will be discarded 1638 * since it is a dup that has already been acked. 1639 * This gives us a lowerbound on the timestamp. 1640 * timestamp >= other last echoed timestamp 1641 * - The timestamp will be less than or equal to 1642 * the last timestamp plus the time between the 1643 * last packet and now. The RFC defines the max 1644 * clock rate as 1ms. We will allow clocks to be 1645 * up to 10% fast and will allow a total difference 1646 * or 30 seconds due to a route change. And this 1647 * gives us an upperbound on the timestamp. 1648 * timestamp <= last timestamp + max ticks 1649 * We have to be careful here. Windows will send an 1650 * initial timestamp of zero and then initialize it 1651 * to a random value after the 3whs; presumably to 1652 * avoid a DoS by having to call an expensive RNG 1653 * during a SYN flood. Proof MS has at least one 1654 * good security geek. 1655 * 1656 * - The TCP timestamp option must also echo the other 1657 * endpoints timestamp. The timestamp echoed is the 1658 * one carried on the earliest unacknowledged segment 1659 * on the left edge of the sequence window. The RFC 1660 * states that the host will reject any echoed 1661 * timestamps that were larger than any ever sent. 1662 * This gives us an upperbound on the TS echo. 1663 * tescr <= largest_tsval 1664 * - The lowerbound on the TS echo is a little more 1665 * tricky to determine. The other endpoint's echoed 1666 * values will not decrease. But there may be 1667 * network conditions that re-order packets and 1668 * cause our view of them to decrease. For now the 1669 * only lowerbound we can safely determine is that 1670 * the TS echo will never be less than the original 1671 * TS. XXX There is probably a better lowerbound. 1672 * Remove TS_MAX_CONN with better lowerbound check. 1673 * tescr >= other original TS 1674 * 1675 * It is also important to note that the fastest 1676 * timestamp clock of 1ms will wrap its 32bit space in 1677 * 24 days. So we just disable TS checking after 24 1678 * days of idle time. We actually must use a 12d 1679 * connection limit until we can come up with a better 1680 * lowerbound to the TS echo check. 1681 */ 1682 struct timeval delta_ts; 1683 int ts_fudge; 1684 1685 1686 /* 1687 * PFTM_TS_DIFF is how many seconds of leeway to allow 1688 * a host's timestamp. This can happen if the previous 1689 * packet got delayed in transit for much longer than 1690 * this packet. 1691 */ 1692 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0) 1693 ts_fudge = pf_default_rule.timeout[PFTM_TS_DIFF]; 1694 1695 1696 /* Calculate max ticks since the last timestamp */ 1697 #define TS_MAXFREQ 1100 /* RFC max TS freq of 1Khz + 10% skew */ 1698 #define TS_MICROSECS 1000000 /* microseconds per second */ 1699 #ifndef timersub 1700 #define timersub(tvp, uvp, vvp) \ 1701 do { \ 1702 (vvp)->tv_sec = (tvp)->tv_sec - (uvp)->tv_sec; \ 1703 (vvp)->tv_usec = (tvp)->tv_usec - (uvp)->tv_usec; \ 1704 if ((vvp)->tv_usec < 0) { \ 1705 (vvp)->tv_sec--; \ 1706 (vvp)->tv_usec += 1000000; \ 1707 } \ 1708 } while (0) 1709 #endif 1710 1711 timersub(&uptime, &src->scrub->pfss_last, &delta_ts); 1712 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ; 1713 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ); 1714 1715 1716 if ((src->state >= TCPS_ESTABLISHED && 1717 dst->state >= TCPS_ESTABLISHED) && 1718 (SEQ_LT(tsval, dst->scrub->pfss_tsecr) || 1719 SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) || 1720 (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) || 1721 SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) { 1722 /* Bad RFC1323 implementation or an insertion attack. 1723 * 1724 * - Solaris 2.6 and 2.7 are known to send another ACK 1725 * after the FIN,FIN|ACK,ACK closing that carries 1726 * an old timestamp. 1727 */ 1728 1729 DPFPRINTF(("Timestamp failed %c%c%c%c\n", 1730 SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ', 1731 SEQ_GT(tsval, src->scrub->pfss_tsval + 1732 tsval_from_last) ? '1' : ' ', 1733 SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ', 1734 SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' ')); 1735 DPFPRINTF((" tsval: %u tsecr: %u +ticks: %u " 1736 "idle: %lus %lums\n", 1737 tsval, tsecr, tsval_from_last, delta_ts.tv_sec, 1738 delta_ts.tv_usec / 1000)); 1739 DPFPRINTF((" src->tsval: %u tsecr: %u\n", 1740 src->scrub->pfss_tsval, src->scrub->pfss_tsecr)); 1741 DPFPRINTF((" dst->tsval: %u tsecr: %u tsval0: %u" 1742 "\n", dst->scrub->pfss_tsval, 1743 dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0)); 1744 if (pf_status.debug >= PF_DEBUG_MISC) { 1745 pf_print_state(state); 1746 pf_print_flags(th->th_flags); 1747 kprintf("\n"); 1748 } 1749 REASON_SET(reason, PFRES_TS); 1750 return (PF_DROP); 1751 } 1752 1753 /* XXX I'd really like to require tsecr but it's optional */ 1754 1755 } else if (!got_ts && (th->th_flags & TH_RST) == 0 && 1756 ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED) 1757 || pd->p_len > 0 || (th->th_flags & TH_SYN)) && 1758 src->scrub && dst->scrub && 1759 (src->scrub->pfss_flags & PFSS_PAWS) && 1760 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1761 /* Didn't send a timestamp. Timestamps aren't really useful 1762 * when: 1763 * - connection opening or closing (often not even sent). 1764 * but we must not let an attacker to put a FIN on a 1765 * data packet to sneak it through our ESTABLISHED check. 1766 * - on a TCP reset. RFC suggests not even looking at TS. 1767 * - on an empty ACK. The TS will not be echoed so it will 1768 * probably not help keep the RTT calculation in sync and 1769 * there isn't as much danger when the sequence numbers 1770 * got wrapped. So some stacks don't include TS on empty 1771 * ACKs :-( 1772 * 1773 * To minimize the disruption to mostly RFC1323 conformant 1774 * stacks, we will only require timestamps on data packets. 1775 * 1776 * And what do ya know, we cannot require timestamps on data 1777 * packets. There appear to be devices that do legitimate 1778 * TCP connection hijacking. There are HTTP devices that allow 1779 * a 3whs (with timestamps) and then buffer the HTTP request. 1780 * If the intermediate device has the HTTP response cache, it 1781 * will spoof the response but not bother timestamping its 1782 * packets. So we can look for the presence of a timestamp in 1783 * the first data packet and if there, require it in all future 1784 * packets. 1785 */ 1786 1787 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) { 1788 /* 1789 * Hey! Someone tried to sneak a packet in. Or the 1790 * stack changed its RFC1323 behavior?!?! 1791 */ 1792 if (pf_status.debug >= PF_DEBUG_MISC) { 1793 DPFPRINTF(("Did not receive expected RFC1323 " 1794 "timestamp\n")); 1795 pf_print_state(state); 1796 pf_print_flags(th->th_flags); 1797 kprintf("\n"); 1798 } 1799 REASON_SET(reason, PFRES_TS); 1800 return (PF_DROP); 1801 } 1802 } 1803 1804 1805 /* 1806 * We will note if a host sends his data packets with or without 1807 * timestamps. And require all data packets to contain a timestamp 1808 * if the first does. PAWS implicitly requires that all data packets be 1809 * timestamped. But I think there are middle-man devices that hijack 1810 * TCP streams immediately after the 3whs and don't timestamp their 1811 * packets (seen in a WWW accelerator or cache). 1812 */ 1813 if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags & 1814 (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) { 1815 if (got_ts) 1816 src->scrub->pfss_flags |= PFSS_DATA_TS; 1817 else { 1818 src->scrub->pfss_flags |= PFSS_DATA_NOTS; 1819 if (pf_status.debug >= PF_DEBUG_MISC && dst->scrub && 1820 (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) { 1821 /* Don't warn if other host rejected RFC1323 */ 1822 DPFPRINTF(("Broken RFC1323 stack did not " 1823 "timestamp data packet. Disabled PAWS " 1824 "security.\n")); 1825 pf_print_state(state); 1826 pf_print_flags(th->th_flags); 1827 kprintf("\n"); 1828 } 1829 } 1830 } 1831 1832 1833 /* 1834 * Update PAWS values 1835 */ 1836 if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags & 1837 (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) { 1838 getmicrouptime(&src->scrub->pfss_last); 1839 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) || 1840 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 1841 src->scrub->pfss_tsval = tsval; 1842 1843 if (tsecr) { 1844 if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) || 1845 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 1846 src->scrub->pfss_tsecr = tsecr; 1847 1848 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 && 1849 (SEQ_LT(tsval, src->scrub->pfss_tsval0) || 1850 src->scrub->pfss_tsval0 == 0)) { 1851 /* tsval0 MUST be the lowest timestamp */ 1852 src->scrub->pfss_tsval0 = tsval; 1853 } 1854 1855 /* Only fully initialized after a TS gets echoed */ 1856 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0) 1857 src->scrub->pfss_flags |= PFSS_PAWS; 1858 } 1859 } 1860 1861 /* I have a dream.... TCP segment reassembly.... */ 1862 return (0); 1863 } 1864 1865 int 1866 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th, 1867 int off, sa_family_t af) 1868 { 1869 u_int16_t *mss; 1870 int thoff; 1871 int opt, cnt, optlen = 0; 1872 int rewrite = 0; 1873 u_char opts[TCP_MAXOLEN]; 1874 u_char *optp = opts; 1875 1876 thoff = th->th_off << 2; 1877 cnt = thoff - sizeof(struct tcphdr); 1878 1879 if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt, 1880 NULL, NULL, af)) 1881 return (rewrite); 1882 1883 for (; cnt > 0; cnt -= optlen, optp += optlen) { 1884 opt = optp[0]; 1885 if (opt == TCPOPT_EOL) 1886 break; 1887 if (opt == TCPOPT_NOP) 1888 optlen = 1; 1889 else { 1890 if (cnt < 2) 1891 break; 1892 optlen = optp[1]; 1893 if (optlen < 2 || optlen > cnt) 1894 break; 1895 } 1896 switch (opt) { 1897 case TCPOPT_MAXSEG: 1898 mss = (u_int16_t *)(optp + 2); 1899 if ((ntohs(*mss)) > r->max_mss) { 1900 th->th_sum = pf_cksum_fixup(th->th_sum, 1901 *mss, htons(r->max_mss), 0); 1902 *mss = htons(r->max_mss); 1903 rewrite = 1; 1904 } 1905 break; 1906 default: 1907 break; 1908 } 1909 } 1910 1911 if (rewrite) 1912 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts); 1913 1914 return (rewrite); 1915 } 1916