1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright 2001 Niels Provos <provos@citi.umich.edu> 5 * Copyright 2011-2018 Alexander Bluhm <bluhm@openbsd.org> 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 * $OpenBSD: pf_norm.c,v 1.114 2009/01/29 14:11:45 henning Exp $ 29 */ 30 31 #include <sys/cdefs.h> 32 __FBSDID("$FreeBSD$"); 33 34 #include "opt_inet.h" 35 #include "opt_inet6.h" 36 #include "opt_pf.h" 37 38 #include <sys/param.h> 39 #include <sys/kernel.h> 40 #include <sys/lock.h> 41 #include <sys/mbuf.h> 42 #include <sys/mutex.h> 43 #include <sys/refcount.h> 44 #include <sys/socket.h> 45 46 #include <net/if.h> 47 #include <net/vnet.h> 48 #include <net/pfvar.h> 49 #include <net/if_pflog.h> 50 51 #include <netinet/in.h> 52 #include <netinet/ip.h> 53 #include <netinet/ip_var.h> 54 #include <netinet6/ip6_var.h> 55 #include <netinet/tcp.h> 56 #include <netinet/tcp_fsm.h> 57 #include <netinet/tcp_seq.h> 58 59 #ifdef INET6 60 #include <netinet/ip6.h> 61 #endif /* INET6 */ 62 63 struct pf_frent { 64 TAILQ_ENTRY(pf_frent) fr_next; 65 struct mbuf *fe_m; 66 uint16_t fe_hdrlen; /* ipv4 header length with ip options 67 ipv6, extension, fragment header */ 68 uint16_t fe_extoff; /* last extension header offset or 0 */ 69 uint16_t fe_len; /* fragment length */ 70 uint16_t fe_off; /* fragment offset */ 71 uint16_t fe_mff; /* more fragment flag */ 72 }; 73 74 struct pf_fragment_cmp { 75 struct pf_addr frc_src; 76 struct pf_addr frc_dst; 77 uint32_t frc_id; 78 sa_family_t frc_af; 79 uint8_t frc_proto; 80 }; 81 82 struct pf_fragment { 83 struct pf_fragment_cmp fr_key; 84 #define fr_src fr_key.frc_src 85 #define fr_dst fr_key.frc_dst 86 #define fr_id fr_key.frc_id 87 #define fr_af fr_key.frc_af 88 #define fr_proto fr_key.frc_proto 89 90 /* pointers to queue element */ 91 struct pf_frent *fr_firstoff[PF_FRAG_ENTRY_POINTS]; 92 /* count entries between pointers */ 93 uint8_t fr_entries[PF_FRAG_ENTRY_POINTS]; 94 RB_ENTRY(pf_fragment) fr_entry; 95 TAILQ_ENTRY(pf_fragment) frag_next; 96 uint32_t fr_timeout; 97 uint16_t fr_maxlen; /* maximum length of single fragment */ 98 u_int16_t fr_holes; /* number of holes in the queue */ 99 TAILQ_HEAD(pf_fragq, pf_frent) fr_queue; 100 }; 101 102 struct pf_fragment_tag { 103 uint16_t ft_hdrlen; /* header length of reassembled pkt */ 104 uint16_t ft_extoff; /* last extension header offset or 0 */ 105 uint16_t ft_maxlen; /* maximum fragment payload length */ 106 uint32_t ft_id; /* fragment id */ 107 }; 108 109 static struct mtx pf_frag_mtx; 110 MTX_SYSINIT(pf_frag_mtx, &pf_frag_mtx, "pf fragments", MTX_DEF); 111 #define PF_FRAG_LOCK() mtx_lock(&pf_frag_mtx) 112 #define PF_FRAG_UNLOCK() mtx_unlock(&pf_frag_mtx) 113 #define PF_FRAG_ASSERT() mtx_assert(&pf_frag_mtx, MA_OWNED) 114 115 VNET_DEFINE(uma_zone_t, pf_state_scrub_z); /* XXX: shared with pfsync */ 116 117 VNET_DEFINE_STATIC(uma_zone_t, pf_frent_z); 118 #define V_pf_frent_z VNET(pf_frent_z) 119 VNET_DEFINE_STATIC(uma_zone_t, pf_frag_z); 120 #define V_pf_frag_z VNET(pf_frag_z) 121 122 TAILQ_HEAD(pf_fragqueue, pf_fragment); 123 TAILQ_HEAD(pf_cachequeue, pf_fragment); 124 VNET_DEFINE_STATIC(struct pf_fragqueue, pf_fragqueue); 125 #define V_pf_fragqueue VNET(pf_fragqueue) 126 RB_HEAD(pf_frag_tree, pf_fragment); 127 VNET_DEFINE_STATIC(struct pf_frag_tree, pf_frag_tree); 128 #define V_pf_frag_tree VNET(pf_frag_tree) 129 static int pf_frag_compare(struct pf_fragment *, 130 struct pf_fragment *); 131 static RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 132 static RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 133 134 static void pf_flush_fragments(void); 135 static void pf_free_fragment(struct pf_fragment *); 136 static void pf_remove_fragment(struct pf_fragment *); 137 static int pf_normalize_tcpopt(struct pf_rule *, struct mbuf *, 138 struct tcphdr *, int, sa_family_t); 139 static struct pf_frent *pf_create_fragment(u_short *); 140 static int pf_frent_holes(struct pf_frent *frent); 141 static struct pf_fragment *pf_find_fragment(struct pf_fragment_cmp *key, 142 struct pf_frag_tree *tree); 143 static inline int pf_frent_index(struct pf_frent *); 144 static int pf_frent_insert(struct pf_fragment *, 145 struct pf_frent *, struct pf_frent *); 146 void pf_frent_remove(struct pf_fragment *, 147 struct pf_frent *); 148 struct pf_frent *pf_frent_previous(struct pf_fragment *, 149 struct pf_frent *); 150 static struct pf_fragment *pf_fillup_fragment(struct pf_fragment_cmp *, 151 struct pf_frent *, u_short *); 152 static struct mbuf *pf_join_fragment(struct pf_fragment *); 153 #ifdef INET 154 static void pf_scrub_ip(struct mbuf **, uint32_t, uint8_t, uint8_t); 155 static int pf_reassemble(struct mbuf **, struct ip *, int, u_short *); 156 #endif /* INET */ 157 #ifdef INET6 158 static int pf_reassemble6(struct mbuf **, struct ip6_hdr *, 159 struct ip6_frag *, uint16_t, uint16_t, u_short *); 160 static void pf_scrub_ip6(struct mbuf **, uint8_t); 161 #endif /* INET6 */ 162 163 #define DPFPRINTF(x) do { \ 164 if (V_pf_status.debug >= PF_DEBUG_MISC) { \ 165 printf("%s: ", __func__); \ 166 printf x ; \ 167 } \ 168 } while(0) 169 170 #ifdef INET 171 static void 172 pf_ip2key(struct ip *ip, int dir, struct pf_fragment_cmp *key) 173 { 174 175 key->frc_src.v4 = ip->ip_src; 176 key->frc_dst.v4 = ip->ip_dst; 177 key->frc_af = AF_INET; 178 key->frc_proto = ip->ip_p; 179 key->frc_id = ip->ip_id; 180 } 181 #endif /* INET */ 182 183 void 184 pf_normalize_init(void) 185 { 186 187 V_pf_frag_z = uma_zcreate("pf frags", sizeof(struct pf_fragment), 188 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 189 V_pf_frent_z = uma_zcreate("pf frag entries", sizeof(struct pf_frent), 190 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 191 V_pf_state_scrub_z = uma_zcreate("pf state scrubs", 192 sizeof(struct pf_state_scrub), NULL, NULL, NULL, NULL, 193 UMA_ALIGN_PTR, 0); 194 195 V_pf_limits[PF_LIMIT_FRAGS].zone = V_pf_frent_z; 196 V_pf_limits[PF_LIMIT_FRAGS].limit = PFFRAG_FRENT_HIWAT; 197 uma_zone_set_max(V_pf_frent_z, PFFRAG_FRENT_HIWAT); 198 uma_zone_set_warning(V_pf_frent_z, "PF frag entries limit reached"); 199 200 TAILQ_INIT(&V_pf_fragqueue); 201 } 202 203 void 204 pf_normalize_cleanup(void) 205 { 206 207 uma_zdestroy(V_pf_state_scrub_z); 208 uma_zdestroy(V_pf_frent_z); 209 uma_zdestroy(V_pf_frag_z); 210 } 211 212 static int 213 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b) 214 { 215 int diff; 216 217 if ((diff = a->fr_id - b->fr_id) != 0) 218 return (diff); 219 if ((diff = a->fr_proto - b->fr_proto) != 0) 220 return (diff); 221 if ((diff = a->fr_af - b->fr_af) != 0) 222 return (diff); 223 if ((diff = pf_addr_cmp(&a->fr_src, &b->fr_src, a->fr_af)) != 0) 224 return (diff); 225 if ((diff = pf_addr_cmp(&a->fr_dst, &b->fr_dst, a->fr_af)) != 0) 226 return (diff); 227 return (0); 228 } 229 230 void 231 pf_purge_expired_fragments(void) 232 { 233 u_int32_t expire = time_uptime - 234 V_pf_default_rule.timeout[PFTM_FRAG]; 235 236 pf_purge_fragments(expire); 237 } 238 239 void 240 pf_purge_fragments(uint32_t expire) 241 { 242 struct pf_fragment *frag; 243 244 PF_FRAG_LOCK(); 245 while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) { 246 if (frag->fr_timeout > expire) 247 break; 248 249 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); 250 pf_free_fragment(frag); 251 } 252 253 PF_FRAG_UNLOCK(); 254 } 255 256 /* 257 * Try to flush old fragments to make space for new ones 258 */ 259 static void 260 pf_flush_fragments(void) 261 { 262 struct pf_fragment *frag; 263 int goal; 264 265 PF_FRAG_ASSERT(); 266 267 goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10; 268 DPFPRINTF(("trying to free %d frag entriess\n", goal)); 269 while (goal < uma_zone_get_cur(V_pf_frent_z)) { 270 frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue); 271 if (frag) 272 pf_free_fragment(frag); 273 else 274 break; 275 } 276 } 277 278 /* Frees the fragments and all associated entries */ 279 static void 280 pf_free_fragment(struct pf_fragment *frag) 281 { 282 struct pf_frent *frent; 283 284 PF_FRAG_ASSERT(); 285 286 /* Free all fragments */ 287 for (frent = TAILQ_FIRST(&frag->fr_queue); frent; 288 frent = TAILQ_FIRST(&frag->fr_queue)) { 289 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 290 291 m_freem(frent->fe_m); 292 uma_zfree(V_pf_frent_z, frent); 293 } 294 295 pf_remove_fragment(frag); 296 } 297 298 static struct pf_fragment * 299 pf_find_fragment(struct pf_fragment_cmp *key, struct pf_frag_tree *tree) 300 { 301 struct pf_fragment *frag; 302 303 PF_FRAG_ASSERT(); 304 305 frag = RB_FIND(pf_frag_tree, tree, (struct pf_fragment *)key); 306 if (frag != NULL) { 307 /* XXX Are we sure we want to update the timeout? */ 308 frag->fr_timeout = time_uptime; 309 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next); 310 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next); 311 } 312 313 return (frag); 314 } 315 316 /* Removes a fragment from the fragment queue and frees the fragment */ 317 static void 318 pf_remove_fragment(struct pf_fragment *frag) 319 { 320 321 PF_FRAG_ASSERT(); 322 KASSERT(frag, ("frag != NULL")); 323 324 RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag); 325 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next); 326 uma_zfree(V_pf_frag_z, frag); 327 } 328 329 static struct pf_frent * 330 pf_create_fragment(u_short *reason) 331 { 332 struct pf_frent *frent; 333 334 PF_FRAG_ASSERT(); 335 336 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT); 337 if (frent == NULL) { 338 pf_flush_fragments(); 339 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT); 340 if (frent == NULL) { 341 REASON_SET(reason, PFRES_MEMORY); 342 return (NULL); 343 } 344 } 345 346 return (frent); 347 } 348 349 /* 350 * Calculate the additional holes that were created in the fragment 351 * queue by inserting this fragment. A fragment in the middle 352 * creates one more hole by splitting. For each connected side, 353 * it loses one hole. 354 * Fragment entry must be in the queue when calling this function. 355 */ 356 static int 357 pf_frent_holes(struct pf_frent *frent) 358 { 359 struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next); 360 struct pf_frent *next = TAILQ_NEXT(frent, fr_next); 361 int holes = 1; 362 363 if (prev == NULL) { 364 if (frent->fe_off == 0) 365 holes--; 366 } else { 367 KASSERT(frent->fe_off != 0, ("frent->fe_off != 0")); 368 if (frent->fe_off == prev->fe_off + prev->fe_len) 369 holes--; 370 } 371 if (next == NULL) { 372 if (!frent->fe_mff) 373 holes--; 374 } else { 375 KASSERT(frent->fe_mff, ("frent->fe_mff")); 376 if (next->fe_off == frent->fe_off + frent->fe_len) 377 holes--; 378 } 379 return holes; 380 } 381 382 static inline int 383 pf_frent_index(struct pf_frent *frent) 384 { 385 /* 386 * We have an array of 16 entry points to the queue. A full size 387 * 65535 octet IP packet can have 8192 fragments. So the queue 388 * traversal length is at most 512 and at most 16 entry points are 389 * checked. We need 128 additional bytes on a 64 bit architecture. 390 */ 391 CTASSERT(((u_int16_t)0xffff &~ 7) / (0x10000 / PF_FRAG_ENTRY_POINTS) == 392 16 - 1); 393 CTASSERT(((u_int16_t)0xffff >> 3) / PF_FRAG_ENTRY_POINTS == 512 - 1); 394 395 return frent->fe_off / (0x10000 / PF_FRAG_ENTRY_POINTS); 396 } 397 398 static int 399 pf_frent_insert(struct pf_fragment *frag, struct pf_frent *frent, 400 struct pf_frent *prev) 401 { 402 int index; 403 404 CTASSERT(PF_FRAG_ENTRY_LIMIT <= 0xff); 405 406 /* 407 * A packet has at most 65536 octets. With 16 entry points, each one 408 * spawns 4096 octets. We limit these to 64 fragments each, which 409 * means on average every fragment must have at least 64 octets. 410 */ 411 index = pf_frent_index(frent); 412 if (frag->fr_entries[index] >= PF_FRAG_ENTRY_LIMIT) 413 return ENOBUFS; 414 frag->fr_entries[index]++; 415 416 if (prev == NULL) { 417 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next); 418 } else { 419 KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off, 420 ("overlapping fragment")); 421 TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next); 422 } 423 424 if (frag->fr_firstoff[index] == NULL) { 425 KASSERT(prev == NULL || pf_frent_index(prev) < index, 426 ("prev == NULL || pf_frent_index(pref) < index")); 427 frag->fr_firstoff[index] = frent; 428 } else { 429 if (frent->fe_off < frag->fr_firstoff[index]->fe_off) { 430 KASSERT(prev == NULL || pf_frent_index(prev) < index, 431 ("prev == NULL || pf_frent_index(pref) < index")); 432 frag->fr_firstoff[index] = frent; 433 } else { 434 KASSERT(prev != NULL, ("prev != NULL")); 435 KASSERT(pf_frent_index(prev) == index, 436 ("pf_frent_index(prev) == index")); 437 } 438 } 439 440 frag->fr_holes += pf_frent_holes(frent); 441 442 return 0; 443 } 444 445 void 446 pf_frent_remove(struct pf_fragment *frag, struct pf_frent *frent) 447 { 448 #ifdef INVARIANTS 449 struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next); 450 #endif 451 struct pf_frent *next = TAILQ_NEXT(frent, fr_next); 452 int index; 453 454 frag->fr_holes -= pf_frent_holes(frent); 455 456 index = pf_frent_index(frent); 457 KASSERT(frag->fr_firstoff[index] != NULL, ("frent not found")); 458 if (frag->fr_firstoff[index]->fe_off == frent->fe_off) { 459 if (next == NULL) { 460 frag->fr_firstoff[index] = NULL; 461 } else { 462 KASSERT(frent->fe_off + frent->fe_len <= next->fe_off, 463 ("overlapping fragment")); 464 if (pf_frent_index(next) == index) { 465 frag->fr_firstoff[index] = next; 466 } else { 467 frag->fr_firstoff[index] = NULL; 468 } 469 } 470 } else { 471 KASSERT(frag->fr_firstoff[index]->fe_off < frent->fe_off, 472 ("frag->fr_firstoff[index]->fe_off < frent->fe_off")); 473 KASSERT(prev != NULL, ("prev != NULL")); 474 KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off, 475 ("overlapping fragment")); 476 KASSERT(pf_frent_index(prev) == index, 477 ("pf_frent_index(prev) == index")); 478 } 479 480 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 481 482 KASSERT(frag->fr_entries[index] > 0, ("No fragments remaining")); 483 frag->fr_entries[index]--; 484 } 485 486 struct pf_frent * 487 pf_frent_previous(struct pf_fragment *frag, struct pf_frent *frent) 488 { 489 struct pf_frent *prev, *next; 490 int index; 491 492 /* 493 * If there are no fragments after frag, take the final one. Assume 494 * that the global queue is not empty. 495 */ 496 prev = TAILQ_LAST(&frag->fr_queue, pf_fragq); 497 KASSERT(prev != NULL, ("prev != NULL")); 498 if (prev->fe_off <= frent->fe_off) 499 return prev; 500 /* 501 * We want to find a fragment entry that is before frag, but still 502 * close to it. Find the first fragment entry that is in the same 503 * entry point or in the first entry point after that. As we have 504 * already checked that there are entries behind frag, this will 505 * succeed. 506 */ 507 for (index = pf_frent_index(frent); index < PF_FRAG_ENTRY_POINTS; 508 index++) { 509 prev = frag->fr_firstoff[index]; 510 if (prev != NULL) 511 break; 512 } 513 KASSERT(prev != NULL, ("prev != NULL")); 514 /* 515 * In prev we may have a fragment from the same entry point that is 516 * before frent, or one that is just one position behind frent. 517 * In the latter case, we go back one step and have the predecessor. 518 * There may be none if the new fragment will be the first one. 519 */ 520 if (prev->fe_off > frent->fe_off) { 521 prev = TAILQ_PREV(prev, pf_fragq, fr_next); 522 if (prev == NULL) 523 return NULL; 524 KASSERT(prev->fe_off <= frent->fe_off, 525 ("prev->fe_off <= frent->fe_off")); 526 return prev; 527 } 528 /* 529 * In prev is the first fragment of the entry point. The offset 530 * of frag is behind it. Find the closest previous fragment. 531 */ 532 for (next = TAILQ_NEXT(prev, fr_next); next != NULL; 533 next = TAILQ_NEXT(next, fr_next)) { 534 if (next->fe_off > frent->fe_off) 535 break; 536 prev = next; 537 } 538 return prev; 539 } 540 541 static struct pf_fragment * 542 pf_fillup_fragment(struct pf_fragment_cmp *key, struct pf_frent *frent, 543 u_short *reason) 544 { 545 struct pf_frent *after, *next, *prev; 546 struct pf_fragment *frag; 547 uint16_t total; 548 549 PF_FRAG_ASSERT(); 550 551 /* No empty fragments. */ 552 if (frent->fe_len == 0) { 553 DPFPRINTF(("bad fragment: len 0")); 554 goto bad_fragment; 555 } 556 557 /* All fragments are 8 byte aligned. */ 558 if (frent->fe_mff && (frent->fe_len & 0x7)) { 559 DPFPRINTF(("bad fragment: mff and len %d", frent->fe_len)); 560 goto bad_fragment; 561 } 562 563 /* Respect maximum length, IP_MAXPACKET == IPV6_MAXPACKET. */ 564 if (frent->fe_off + frent->fe_len > IP_MAXPACKET) { 565 DPFPRINTF(("bad fragment: max packet %d", 566 frent->fe_off + frent->fe_len)); 567 goto bad_fragment; 568 } 569 570 DPFPRINTF((key->frc_af == AF_INET ? 571 "reass frag %d @ %d-%d" : "reass frag %#08x @ %d-%d", 572 key->frc_id, frent->fe_off, frent->fe_off + frent->fe_len)); 573 574 /* Fully buffer all of the fragments in this fragment queue. */ 575 frag = pf_find_fragment(key, &V_pf_frag_tree); 576 577 /* Create a new reassembly queue for this packet. */ 578 if (frag == NULL) { 579 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 580 if (frag == NULL) { 581 pf_flush_fragments(); 582 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 583 if (frag == NULL) { 584 REASON_SET(reason, PFRES_MEMORY); 585 goto drop_fragment; 586 } 587 } 588 589 *(struct pf_fragment_cmp *)frag = *key; 590 memset(frag->fr_firstoff, 0, sizeof(frag->fr_firstoff)); 591 memset(frag->fr_entries, 0, sizeof(frag->fr_entries)); 592 frag->fr_timeout = time_uptime; 593 frag->fr_maxlen = frent->fe_len; 594 frag->fr_holes = 1; 595 TAILQ_INIT(&frag->fr_queue); 596 597 RB_INSERT(pf_frag_tree, &V_pf_frag_tree, frag); 598 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next); 599 600 /* We do not have a previous fragment, cannot fail. */ 601 pf_frent_insert(frag, frent, NULL); 602 603 return (frag); 604 } 605 606 KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue")); 607 608 /* Remember maximum fragment len for refragmentation. */ 609 if (frent->fe_len > frag->fr_maxlen) 610 frag->fr_maxlen = frent->fe_len; 611 612 /* Maximum data we have seen already. */ 613 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 614 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 615 616 /* Non terminal fragments must have more fragments flag. */ 617 if (frent->fe_off + frent->fe_len < total && !frent->fe_mff) 618 goto bad_fragment; 619 620 /* Check if we saw the last fragment already. */ 621 if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) { 622 if (frent->fe_off + frent->fe_len > total || 623 (frent->fe_off + frent->fe_len == total && frent->fe_mff)) 624 goto bad_fragment; 625 } else { 626 if (frent->fe_off + frent->fe_len == total && !frent->fe_mff) 627 goto bad_fragment; 628 } 629 630 /* Find neighbors for newly inserted fragment */ 631 prev = pf_frent_previous(frag, frent); 632 if (prev == NULL) { 633 after = TAILQ_FIRST(&frag->fr_queue); 634 KASSERT(after != NULL, ("after != NULL")); 635 } else { 636 after = TAILQ_NEXT(prev, fr_next); 637 } 638 639 if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) { 640 uint16_t precut; 641 642 precut = prev->fe_off + prev->fe_len - frent->fe_off; 643 if (precut >= frent->fe_len) 644 goto bad_fragment; 645 DPFPRINTF(("overlap -%d", precut)); 646 m_adj(frent->fe_m, precut); 647 frent->fe_off += precut; 648 frent->fe_len -= precut; 649 } 650 651 for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off; 652 after = next) { 653 uint16_t aftercut; 654 655 aftercut = frent->fe_off + frent->fe_len - after->fe_off; 656 DPFPRINTF(("adjust overlap %d", aftercut)); 657 if (aftercut < after->fe_len) { 658 m_adj(after->fe_m, aftercut); 659 after->fe_off += aftercut; 660 after->fe_len -= aftercut; 661 break; 662 } 663 664 /* This fragment is completely overlapped, lose it. */ 665 next = TAILQ_NEXT(after, fr_next); 666 pf_frent_remove(frag, after); 667 m_freem(after->fe_m); 668 uma_zfree(V_pf_frent_z, after); 669 } 670 671 /* If part of the queue gets too long, there is not way to recover. */ 672 if (pf_frent_insert(frag, frent, prev)) { 673 DPFPRINTF(("fragment queue limit exceeded")); 674 goto bad_fragment; 675 } 676 677 return (frag); 678 679 bad_fragment: 680 REASON_SET(reason, PFRES_FRAG); 681 drop_fragment: 682 uma_zfree(V_pf_frent_z, frent); 683 return (NULL); 684 } 685 686 static struct mbuf * 687 pf_join_fragment(struct pf_fragment *frag) 688 { 689 struct mbuf *m, *m2; 690 struct pf_frent *frent, *next; 691 692 frent = TAILQ_FIRST(&frag->fr_queue); 693 next = TAILQ_NEXT(frent, fr_next); 694 695 m = frent->fe_m; 696 m_adj(m, (frent->fe_hdrlen + frent->fe_len) - m->m_pkthdr.len); 697 uma_zfree(V_pf_frent_z, frent); 698 for (frent = next; frent != NULL; frent = next) { 699 next = TAILQ_NEXT(frent, fr_next); 700 701 m2 = frent->fe_m; 702 /* Strip off ip header. */ 703 m_adj(m2, frent->fe_hdrlen); 704 /* Strip off any trailing bytes. */ 705 m_adj(m2, frent->fe_len - m2->m_pkthdr.len); 706 707 uma_zfree(V_pf_frent_z, frent); 708 m_cat(m, m2); 709 } 710 711 /* Remove from fragment queue. */ 712 pf_remove_fragment(frag); 713 714 return (m); 715 } 716 717 #ifdef INET 718 static int 719 pf_reassemble(struct mbuf **m0, struct ip *ip, int dir, u_short *reason) 720 { 721 struct mbuf *m = *m0; 722 struct pf_frent *frent; 723 struct pf_fragment *frag; 724 struct pf_fragment_cmp key; 725 uint16_t total, hdrlen; 726 727 /* Get an entry for the fragment queue */ 728 if ((frent = pf_create_fragment(reason)) == NULL) 729 return (PF_DROP); 730 731 frent->fe_m = m; 732 frent->fe_hdrlen = ip->ip_hl << 2; 733 frent->fe_extoff = 0; 734 frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2); 735 frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3; 736 frent->fe_mff = ntohs(ip->ip_off) & IP_MF; 737 738 pf_ip2key(ip, dir, &key); 739 740 if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) 741 return (PF_DROP); 742 743 /* The mbuf is part of the fragment entry, no direct free or access */ 744 m = *m0 = NULL; 745 746 if (frag->fr_holes) { 747 DPFPRINTF(("frag %d, holes %d", frag->fr_id, frag->fr_holes)); 748 return (PF_PASS); /* drop because *m0 is NULL, no error */ 749 } 750 751 /* We have all the data */ 752 frent = TAILQ_FIRST(&frag->fr_queue); 753 KASSERT(frent != NULL, ("frent != NULL")); 754 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 755 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 756 hdrlen = frent->fe_hdrlen; 757 758 m = *m0 = pf_join_fragment(frag); 759 frag = NULL; 760 761 if (m->m_flags & M_PKTHDR) { 762 int plen = 0; 763 for (m = *m0; m; m = m->m_next) 764 plen += m->m_len; 765 m = *m0; 766 m->m_pkthdr.len = plen; 767 } 768 769 ip = mtod(m, struct ip *); 770 ip->ip_len = htons(hdrlen + total); 771 ip->ip_off &= ~(IP_MF|IP_OFFMASK); 772 773 if (hdrlen + total > IP_MAXPACKET) { 774 DPFPRINTF(("drop: too big: %d", total)); 775 ip->ip_len = 0; 776 REASON_SET(reason, PFRES_SHORT); 777 /* PF_DROP requires a valid mbuf *m0 in pf_test() */ 778 return (PF_DROP); 779 } 780 781 DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len))); 782 return (PF_PASS); 783 } 784 #endif /* INET */ 785 786 #ifdef INET6 787 static int 788 pf_reassemble6(struct mbuf **m0, struct ip6_hdr *ip6, struct ip6_frag *fraghdr, 789 uint16_t hdrlen, uint16_t extoff, u_short *reason) 790 { 791 struct mbuf *m = *m0; 792 struct pf_frent *frent; 793 struct pf_fragment *frag; 794 struct pf_fragment_cmp key; 795 struct m_tag *mtag; 796 struct pf_fragment_tag *ftag; 797 int off; 798 uint32_t frag_id; 799 uint16_t total, maxlen; 800 uint8_t proto; 801 802 PF_FRAG_LOCK(); 803 804 /* Get an entry for the fragment queue. */ 805 if ((frent = pf_create_fragment(reason)) == NULL) { 806 PF_FRAG_UNLOCK(); 807 return (PF_DROP); 808 } 809 810 frent->fe_m = m; 811 frent->fe_hdrlen = hdrlen; 812 frent->fe_extoff = extoff; 813 frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen; 814 frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK); 815 frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG; 816 817 key.frc_src.v6 = ip6->ip6_src; 818 key.frc_dst.v6 = ip6->ip6_dst; 819 key.frc_af = AF_INET6; 820 /* Only the first fragment's protocol is relevant. */ 821 key.frc_proto = 0; 822 key.frc_id = fraghdr->ip6f_ident; 823 824 if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) { 825 PF_FRAG_UNLOCK(); 826 return (PF_DROP); 827 } 828 829 /* The mbuf is part of the fragment entry, no direct free or access. */ 830 m = *m0 = NULL; 831 832 if (frag->fr_holes) { 833 DPFPRINTF(("frag %d, holes %d", frag->fr_id, frag->fr_holes)); 834 PF_FRAG_UNLOCK(); 835 return (PF_PASS); /* Drop because *m0 is NULL, no error. */ 836 } 837 838 /* We have all the data. */ 839 frent = TAILQ_FIRST(&frag->fr_queue); 840 KASSERT(frent != NULL, ("frent != NULL")); 841 extoff = frent->fe_extoff; 842 maxlen = frag->fr_maxlen; 843 frag_id = frag->fr_id; 844 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 845 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 846 hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag); 847 848 m = *m0 = pf_join_fragment(frag); 849 frag = NULL; 850 851 PF_FRAG_UNLOCK(); 852 853 /* Take protocol from first fragment header. */ 854 m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off); 855 KASSERT(m, ("%s: short mbuf chain", __func__)); 856 proto = *(mtod(m, caddr_t) + off); 857 m = *m0; 858 859 /* Delete frag6 header */ 860 if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0) 861 goto fail; 862 863 if (m->m_flags & M_PKTHDR) { 864 int plen = 0; 865 for (m = *m0; m; m = m->m_next) 866 plen += m->m_len; 867 m = *m0; 868 m->m_pkthdr.len = plen; 869 } 870 871 if ((mtag = m_tag_get(PF_REASSEMBLED, sizeof(struct pf_fragment_tag), 872 M_NOWAIT)) == NULL) 873 goto fail; 874 ftag = (struct pf_fragment_tag *)(mtag + 1); 875 ftag->ft_hdrlen = hdrlen; 876 ftag->ft_extoff = extoff; 877 ftag->ft_maxlen = maxlen; 878 ftag->ft_id = frag_id; 879 m_tag_prepend(m, mtag); 880 881 ip6 = mtod(m, struct ip6_hdr *); 882 ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total); 883 if (extoff) { 884 /* Write protocol into next field of last extension header. */ 885 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt), 886 &off); 887 KASSERT(m, ("%s: short mbuf chain", __func__)); 888 *(mtod(m, char *) + off) = proto; 889 m = *m0; 890 } else 891 ip6->ip6_nxt = proto; 892 893 if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) { 894 DPFPRINTF(("drop: too big: %d", total)); 895 ip6->ip6_plen = 0; 896 REASON_SET(reason, PFRES_SHORT); 897 /* PF_DROP requires a valid mbuf *m0 in pf_test6(). */ 898 return (PF_DROP); 899 } 900 901 DPFPRINTF(("complete: %p(%d)", m, ntohs(ip6->ip6_plen))); 902 return (PF_PASS); 903 904 fail: 905 REASON_SET(reason, PFRES_MEMORY); 906 /* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */ 907 return (PF_DROP); 908 } 909 #endif /* INET6 */ 910 911 #ifdef INET6 912 int 913 pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag) 914 { 915 struct mbuf *m = *m0, *t; 916 struct pf_fragment_tag *ftag = (struct pf_fragment_tag *)(mtag + 1); 917 struct pf_pdesc pd; 918 uint32_t frag_id; 919 uint16_t hdrlen, extoff, maxlen; 920 uint8_t proto; 921 int error, action; 922 923 hdrlen = ftag->ft_hdrlen; 924 extoff = ftag->ft_extoff; 925 maxlen = ftag->ft_maxlen; 926 frag_id = ftag->ft_id; 927 m_tag_delete(m, mtag); 928 mtag = NULL; 929 ftag = NULL; 930 931 if (extoff) { 932 int off; 933 934 /* Use protocol from next field of last extension header */ 935 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt), 936 &off); 937 KASSERT((m != NULL), ("pf_refragment6: short mbuf chain")); 938 proto = *(mtod(m, caddr_t) + off); 939 *(mtod(m, char *) + off) = IPPROTO_FRAGMENT; 940 m = *m0; 941 } else { 942 struct ip6_hdr *hdr; 943 944 hdr = mtod(m, struct ip6_hdr *); 945 proto = hdr->ip6_nxt; 946 hdr->ip6_nxt = IPPROTO_FRAGMENT; 947 } 948 949 /* The MTU must be a multiple of 8 bytes, or we risk doing the 950 * fragmentation wrong. */ 951 maxlen = maxlen & ~7; 952 953 /* 954 * Maxlen may be less than 8 if there was only a single 955 * fragment. As it was fragmented before, add a fragment 956 * header also for a single fragment. If total or maxlen 957 * is less than 8, ip6_fragment() will return EMSGSIZE and 958 * we drop the packet. 959 */ 960 error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id); 961 m = (*m0)->m_nextpkt; 962 (*m0)->m_nextpkt = NULL; 963 if (error == 0) { 964 /* The first mbuf contains the unfragmented packet. */ 965 m_freem(*m0); 966 *m0 = NULL; 967 action = PF_PASS; 968 } else { 969 /* Drop expects an mbuf to free. */ 970 DPFPRINTF(("refragment error %d", error)); 971 action = PF_DROP; 972 } 973 for (t = m; m; m = t) { 974 t = m->m_nextpkt; 975 m->m_nextpkt = NULL; 976 m->m_flags |= M_SKIP_FIREWALL; 977 memset(&pd, 0, sizeof(pd)); 978 pd.pf_mtag = pf_find_mtag(m); 979 if (error == 0) 980 ip6_forward(m, 0); 981 else 982 m_freem(m); 983 } 984 985 return (action); 986 } 987 #endif /* INET6 */ 988 989 #ifdef INET 990 int 991 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason, 992 struct pf_pdesc *pd) 993 { 994 struct mbuf *m = *m0; 995 struct pf_rule *r; 996 struct ip *h = mtod(m, struct ip *); 997 int mff = (ntohs(h->ip_off) & IP_MF); 998 int hlen = h->ip_hl << 2; 999 u_int16_t fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3; 1000 u_int16_t max; 1001 int ip_len; 1002 int ip_off; 1003 int tag = -1; 1004 int verdict; 1005 1006 PF_RULES_RASSERT(); 1007 1008 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1009 while (r != NULL) { 1010 r->evaluations++; 1011 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1012 r = r->skip[PF_SKIP_IFP].ptr; 1013 else if (r->direction && r->direction != dir) 1014 r = r->skip[PF_SKIP_DIR].ptr; 1015 else if (r->af && r->af != AF_INET) 1016 r = r->skip[PF_SKIP_AF].ptr; 1017 else if (r->proto && r->proto != h->ip_p) 1018 r = r->skip[PF_SKIP_PROTO].ptr; 1019 else if (PF_MISMATCHAW(&r->src.addr, 1020 (struct pf_addr *)&h->ip_src.s_addr, AF_INET, 1021 r->src.neg, kif, M_GETFIB(m))) 1022 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1023 else if (PF_MISMATCHAW(&r->dst.addr, 1024 (struct pf_addr *)&h->ip_dst.s_addr, AF_INET, 1025 r->dst.neg, NULL, M_GETFIB(m))) 1026 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1027 else if (r->match_tag && !pf_match_tag(m, r, &tag, 1028 pd->pf_mtag ? pd->pf_mtag->tag : 0)) 1029 r = TAILQ_NEXT(r, entries); 1030 else 1031 break; 1032 } 1033 1034 if (r == NULL || r->action == PF_NOSCRUB) 1035 return (PF_PASS); 1036 else { 1037 r->packets[dir == PF_OUT]++; 1038 r->bytes[dir == PF_OUT] += pd->tot_len; 1039 } 1040 1041 /* Check for illegal packets */ 1042 if (hlen < (int)sizeof(struct ip)) { 1043 REASON_SET(reason, PFRES_NORM); 1044 goto drop; 1045 } 1046 1047 if (hlen > ntohs(h->ip_len)) { 1048 REASON_SET(reason, PFRES_NORM); 1049 goto drop; 1050 } 1051 1052 /* Clear IP_DF if the rule uses the no-df option */ 1053 if (r->rule_flag & PFRULE_NODF && h->ip_off & htons(IP_DF)) { 1054 u_int16_t ip_off = h->ip_off; 1055 1056 h->ip_off &= htons(~IP_DF); 1057 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1058 } 1059 1060 /* We will need other tests here */ 1061 if (!fragoff && !mff) 1062 goto no_fragment; 1063 1064 /* We're dealing with a fragment now. Don't allow fragments 1065 * with IP_DF to enter the cache. If the flag was cleared by 1066 * no-df above, fine. Otherwise drop it. 1067 */ 1068 if (h->ip_off & htons(IP_DF)) { 1069 DPFPRINTF(("IP_DF\n")); 1070 goto bad; 1071 } 1072 1073 ip_len = ntohs(h->ip_len) - hlen; 1074 ip_off = (ntohs(h->ip_off) & IP_OFFMASK) << 3; 1075 1076 /* All fragments are 8 byte aligned */ 1077 if (mff && (ip_len & 0x7)) { 1078 DPFPRINTF(("mff and %d\n", ip_len)); 1079 goto bad; 1080 } 1081 1082 /* Respect maximum length */ 1083 if (fragoff + ip_len > IP_MAXPACKET) { 1084 DPFPRINTF(("max packet %d\n", fragoff + ip_len)); 1085 goto bad; 1086 } 1087 max = fragoff + ip_len; 1088 1089 /* Fully buffer all of the fragments 1090 * Might return a completely reassembled mbuf, or NULL */ 1091 PF_FRAG_LOCK(); 1092 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max)); 1093 verdict = pf_reassemble(m0, h, dir, reason); 1094 PF_FRAG_UNLOCK(); 1095 1096 if (verdict != PF_PASS) 1097 return (PF_DROP); 1098 1099 m = *m0; 1100 if (m == NULL) 1101 return (PF_DROP); 1102 1103 h = mtod(m, struct ip *); 1104 1105 no_fragment: 1106 /* At this point, only IP_DF is allowed in ip_off */ 1107 if (h->ip_off & ~htons(IP_DF)) { 1108 u_int16_t ip_off = h->ip_off; 1109 1110 h->ip_off &= htons(IP_DF); 1111 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1112 } 1113 1114 pf_scrub_ip(&m, r->rule_flag, r->min_ttl, r->set_tos); 1115 1116 return (PF_PASS); 1117 1118 bad: 1119 DPFPRINTF(("dropping bad fragment\n")); 1120 REASON_SET(reason, PFRES_FRAG); 1121 drop: 1122 if (r != NULL && r->log) 1123 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd, 1124 1); 1125 1126 return (PF_DROP); 1127 } 1128 #endif 1129 1130 #ifdef INET6 1131 int 1132 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif, 1133 u_short *reason, struct pf_pdesc *pd) 1134 { 1135 struct mbuf *m = *m0; 1136 struct pf_rule *r; 1137 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1138 int extoff; 1139 int off; 1140 struct ip6_ext ext; 1141 struct ip6_opt opt; 1142 struct ip6_frag frag; 1143 u_int32_t plen; 1144 int optend; 1145 int ooff; 1146 u_int8_t proto; 1147 int terminal; 1148 1149 PF_RULES_RASSERT(); 1150 1151 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1152 while (r != NULL) { 1153 r->evaluations++; 1154 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1155 r = r->skip[PF_SKIP_IFP].ptr; 1156 else if (r->direction && r->direction != dir) 1157 r = r->skip[PF_SKIP_DIR].ptr; 1158 else if (r->af && r->af != AF_INET6) 1159 r = r->skip[PF_SKIP_AF].ptr; 1160 #if 0 /* header chain! */ 1161 else if (r->proto && r->proto != h->ip6_nxt) 1162 r = r->skip[PF_SKIP_PROTO].ptr; 1163 #endif 1164 else if (PF_MISMATCHAW(&r->src.addr, 1165 (struct pf_addr *)&h->ip6_src, AF_INET6, 1166 r->src.neg, kif, M_GETFIB(m))) 1167 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1168 else if (PF_MISMATCHAW(&r->dst.addr, 1169 (struct pf_addr *)&h->ip6_dst, AF_INET6, 1170 r->dst.neg, NULL, M_GETFIB(m))) 1171 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1172 else 1173 break; 1174 } 1175 1176 if (r == NULL || r->action == PF_NOSCRUB) 1177 return (PF_PASS); 1178 else { 1179 r->packets[dir == PF_OUT]++; 1180 r->bytes[dir == PF_OUT] += pd->tot_len; 1181 } 1182 1183 /* Check for illegal packets */ 1184 if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len) 1185 goto drop; 1186 1187 plen = ntohs(h->ip6_plen); 1188 /* jumbo payload option not supported */ 1189 if (plen == 0) 1190 goto drop; 1191 1192 extoff = 0; 1193 off = sizeof(struct ip6_hdr); 1194 proto = h->ip6_nxt; 1195 terminal = 0; 1196 do { 1197 switch (proto) { 1198 case IPPROTO_FRAGMENT: 1199 goto fragment; 1200 break; 1201 case IPPROTO_AH: 1202 case IPPROTO_ROUTING: 1203 case IPPROTO_DSTOPTS: 1204 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1205 NULL, AF_INET6)) 1206 goto shortpkt; 1207 extoff = off; 1208 if (proto == IPPROTO_AH) 1209 off += (ext.ip6e_len + 2) * 4; 1210 else 1211 off += (ext.ip6e_len + 1) * 8; 1212 proto = ext.ip6e_nxt; 1213 break; 1214 case IPPROTO_HOPOPTS: 1215 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1216 NULL, AF_INET6)) 1217 goto shortpkt; 1218 extoff = off; 1219 optend = off + (ext.ip6e_len + 1) * 8; 1220 ooff = off + sizeof(ext); 1221 do { 1222 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type, 1223 sizeof(opt.ip6o_type), NULL, NULL, 1224 AF_INET6)) 1225 goto shortpkt; 1226 if (opt.ip6o_type == IP6OPT_PAD1) { 1227 ooff++; 1228 continue; 1229 } 1230 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt), 1231 NULL, NULL, AF_INET6)) 1232 goto shortpkt; 1233 if (ooff + sizeof(opt) + opt.ip6o_len > optend) 1234 goto drop; 1235 if (opt.ip6o_type == IP6OPT_JUMBO) 1236 goto drop; 1237 ooff += sizeof(opt) + opt.ip6o_len; 1238 } while (ooff < optend); 1239 1240 off = optend; 1241 proto = ext.ip6e_nxt; 1242 break; 1243 default: 1244 terminal = 1; 1245 break; 1246 } 1247 } while (!terminal); 1248 1249 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1250 goto shortpkt; 1251 1252 pf_scrub_ip6(&m, r->min_ttl); 1253 1254 return (PF_PASS); 1255 1256 fragment: 1257 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1258 goto shortpkt; 1259 1260 if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6)) 1261 goto shortpkt; 1262 1263 /* Offset now points to data portion. */ 1264 off += sizeof(frag); 1265 1266 /* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */ 1267 if (pf_reassemble6(m0, h, &frag, off, extoff, reason) != PF_PASS) 1268 return (PF_DROP); 1269 m = *m0; 1270 if (m == NULL) 1271 return (PF_DROP); 1272 1273 pd->flags |= PFDESC_IP_REAS; 1274 return (PF_PASS); 1275 1276 shortpkt: 1277 REASON_SET(reason, PFRES_SHORT); 1278 if (r != NULL && r->log) 1279 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd, 1280 1); 1281 return (PF_DROP); 1282 1283 drop: 1284 REASON_SET(reason, PFRES_NORM); 1285 if (r != NULL && r->log) 1286 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd, 1287 1); 1288 return (PF_DROP); 1289 } 1290 #endif /* INET6 */ 1291 1292 int 1293 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff, 1294 int off, void *h, struct pf_pdesc *pd) 1295 { 1296 struct pf_rule *r, *rm = NULL; 1297 struct tcphdr *th = pd->hdr.tcp; 1298 int rewrite = 0; 1299 u_short reason; 1300 u_int8_t flags; 1301 sa_family_t af = pd->af; 1302 1303 PF_RULES_RASSERT(); 1304 1305 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1306 while (r != NULL) { 1307 r->evaluations++; 1308 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1309 r = r->skip[PF_SKIP_IFP].ptr; 1310 else if (r->direction && r->direction != dir) 1311 r = r->skip[PF_SKIP_DIR].ptr; 1312 else if (r->af && r->af != af) 1313 r = r->skip[PF_SKIP_AF].ptr; 1314 else if (r->proto && r->proto != pd->proto) 1315 r = r->skip[PF_SKIP_PROTO].ptr; 1316 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, 1317 r->src.neg, kif, M_GETFIB(m))) 1318 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1319 else if (r->src.port_op && !pf_match_port(r->src.port_op, 1320 r->src.port[0], r->src.port[1], th->th_sport)) 1321 r = r->skip[PF_SKIP_SRC_PORT].ptr; 1322 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, 1323 r->dst.neg, NULL, M_GETFIB(m))) 1324 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1325 else if (r->dst.port_op && !pf_match_port(r->dst.port_op, 1326 r->dst.port[0], r->dst.port[1], th->th_dport)) 1327 r = r->skip[PF_SKIP_DST_PORT].ptr; 1328 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match( 1329 pf_osfp_fingerprint(pd, m, off, th), 1330 r->os_fingerprint)) 1331 r = TAILQ_NEXT(r, entries); 1332 else { 1333 rm = r; 1334 break; 1335 } 1336 } 1337 1338 if (rm == NULL || rm->action == PF_NOSCRUB) 1339 return (PF_PASS); 1340 else { 1341 r->packets[dir == PF_OUT]++; 1342 r->bytes[dir == PF_OUT] += pd->tot_len; 1343 } 1344 1345 if (rm->rule_flag & PFRULE_REASSEMBLE_TCP) 1346 pd->flags |= PFDESC_TCP_NORM; 1347 1348 flags = th->th_flags; 1349 if (flags & TH_SYN) { 1350 /* Illegal packet */ 1351 if (flags & TH_RST) 1352 goto tcp_drop; 1353 1354 if (flags & TH_FIN) 1355 goto tcp_drop; 1356 } else { 1357 /* Illegal packet */ 1358 if (!(flags & (TH_ACK|TH_RST))) 1359 goto tcp_drop; 1360 } 1361 1362 if (!(flags & TH_ACK)) { 1363 /* These flags are only valid if ACK is set */ 1364 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG)) 1365 goto tcp_drop; 1366 } 1367 1368 /* Check for illegal header length */ 1369 if (th->th_off < (sizeof(struct tcphdr) >> 2)) 1370 goto tcp_drop; 1371 1372 /* If flags changed, or reserved data set, then adjust */ 1373 if (flags != th->th_flags || th->th_x2 != 0) { 1374 u_int16_t ov, nv; 1375 1376 ov = *(u_int16_t *)(&th->th_ack + 1); 1377 th->th_flags = flags; 1378 th->th_x2 = 0; 1379 nv = *(u_int16_t *)(&th->th_ack + 1); 1380 1381 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, ov, nv, 0); 1382 rewrite = 1; 1383 } 1384 1385 /* Remove urgent pointer, if TH_URG is not set */ 1386 if (!(flags & TH_URG) && th->th_urp) { 1387 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, th->th_urp, 1388 0, 0); 1389 th->th_urp = 0; 1390 rewrite = 1; 1391 } 1392 1393 /* Process options */ 1394 if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af)) 1395 rewrite = 1; 1396 1397 /* copy back packet headers if we sanitized */ 1398 if (rewrite) 1399 m_copyback(m, off, sizeof(*th), (caddr_t)th); 1400 1401 return (PF_PASS); 1402 1403 tcp_drop: 1404 REASON_SET(&reason, PFRES_NORM); 1405 if (rm != NULL && r->log) 1406 PFLOG_PACKET(kif, m, AF_INET, dir, reason, r, NULL, NULL, pd, 1407 1); 1408 return (PF_DROP); 1409 } 1410 1411 int 1412 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd, 1413 struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst) 1414 { 1415 u_int32_t tsval, tsecr; 1416 u_int8_t hdr[60]; 1417 u_int8_t *opt; 1418 1419 KASSERT((src->scrub == NULL), 1420 ("pf_normalize_tcp_init: src->scrub != NULL")); 1421 1422 src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT); 1423 if (src->scrub == NULL) 1424 return (1); 1425 1426 switch (pd->af) { 1427 #ifdef INET 1428 case AF_INET: { 1429 struct ip *h = mtod(m, struct ip *); 1430 src->scrub->pfss_ttl = h->ip_ttl; 1431 break; 1432 } 1433 #endif /* INET */ 1434 #ifdef INET6 1435 case AF_INET6: { 1436 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1437 src->scrub->pfss_ttl = h->ip6_hlim; 1438 break; 1439 } 1440 #endif /* INET6 */ 1441 } 1442 1443 1444 /* 1445 * All normalizations below are only begun if we see the start of 1446 * the connections. They must all set an enabled bit in pfss_flags 1447 */ 1448 if ((th->th_flags & TH_SYN) == 0) 1449 return (0); 1450 1451 1452 if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub && 1453 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1454 /* Diddle with TCP options */ 1455 int hlen; 1456 opt = hdr + sizeof(struct tcphdr); 1457 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1458 while (hlen >= TCPOLEN_TIMESTAMP) { 1459 switch (*opt) { 1460 case TCPOPT_EOL: /* FALLTHROUGH */ 1461 case TCPOPT_NOP: 1462 opt++; 1463 hlen--; 1464 break; 1465 case TCPOPT_TIMESTAMP: 1466 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1467 src->scrub->pfss_flags |= 1468 PFSS_TIMESTAMP; 1469 src->scrub->pfss_ts_mod = 1470 htonl(arc4random()); 1471 1472 /* note PFSS_PAWS not set yet */ 1473 memcpy(&tsval, &opt[2], 1474 sizeof(u_int32_t)); 1475 memcpy(&tsecr, &opt[6], 1476 sizeof(u_int32_t)); 1477 src->scrub->pfss_tsval0 = ntohl(tsval); 1478 src->scrub->pfss_tsval = ntohl(tsval); 1479 src->scrub->pfss_tsecr = ntohl(tsecr); 1480 getmicrouptime(&src->scrub->pfss_last); 1481 } 1482 /* FALLTHROUGH */ 1483 default: 1484 hlen -= MAX(opt[1], 2); 1485 opt += MAX(opt[1], 2); 1486 break; 1487 } 1488 } 1489 } 1490 1491 return (0); 1492 } 1493 1494 void 1495 pf_normalize_tcp_cleanup(struct pf_state *state) 1496 { 1497 if (state->src.scrub) 1498 uma_zfree(V_pf_state_scrub_z, state->src.scrub); 1499 if (state->dst.scrub) 1500 uma_zfree(V_pf_state_scrub_z, state->dst.scrub); 1501 1502 /* Someday... flush the TCP segment reassembly descriptors. */ 1503 } 1504 1505 int 1506 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd, 1507 u_short *reason, struct tcphdr *th, struct pf_state *state, 1508 struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback) 1509 { 1510 struct timeval uptime; 1511 u_int32_t tsval, tsecr; 1512 u_int tsval_from_last; 1513 u_int8_t hdr[60]; 1514 u_int8_t *opt; 1515 int copyback = 0; 1516 int got_ts = 0; 1517 1518 KASSERT((src->scrub || dst->scrub), 1519 ("%s: src->scrub && dst->scrub!", __func__)); 1520 1521 /* 1522 * Enforce the minimum TTL seen for this connection. Negate a common 1523 * technique to evade an intrusion detection system and confuse 1524 * firewall state code. 1525 */ 1526 switch (pd->af) { 1527 #ifdef INET 1528 case AF_INET: { 1529 if (src->scrub) { 1530 struct ip *h = mtod(m, struct ip *); 1531 if (h->ip_ttl > src->scrub->pfss_ttl) 1532 src->scrub->pfss_ttl = h->ip_ttl; 1533 h->ip_ttl = src->scrub->pfss_ttl; 1534 } 1535 break; 1536 } 1537 #endif /* INET */ 1538 #ifdef INET6 1539 case AF_INET6: { 1540 if (src->scrub) { 1541 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1542 if (h->ip6_hlim > src->scrub->pfss_ttl) 1543 src->scrub->pfss_ttl = h->ip6_hlim; 1544 h->ip6_hlim = src->scrub->pfss_ttl; 1545 } 1546 break; 1547 } 1548 #endif /* INET6 */ 1549 } 1550 1551 if (th->th_off > (sizeof(struct tcphdr) >> 2) && 1552 ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) || 1553 (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) && 1554 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1555 /* Diddle with TCP options */ 1556 int hlen; 1557 opt = hdr + sizeof(struct tcphdr); 1558 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1559 while (hlen >= TCPOLEN_TIMESTAMP) { 1560 switch (*opt) { 1561 case TCPOPT_EOL: /* FALLTHROUGH */ 1562 case TCPOPT_NOP: 1563 opt++; 1564 hlen--; 1565 break; 1566 case TCPOPT_TIMESTAMP: 1567 /* Modulate the timestamps. Can be used for 1568 * NAT detection, OS uptime determination or 1569 * reboot detection. 1570 */ 1571 1572 if (got_ts) { 1573 /* Huh? Multiple timestamps!? */ 1574 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1575 DPFPRINTF(("multiple TS??")); 1576 pf_print_state(state); 1577 printf("\n"); 1578 } 1579 REASON_SET(reason, PFRES_TS); 1580 return (PF_DROP); 1581 } 1582 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1583 memcpy(&tsval, &opt[2], 1584 sizeof(u_int32_t)); 1585 if (tsval && src->scrub && 1586 (src->scrub->pfss_flags & 1587 PFSS_TIMESTAMP)) { 1588 tsval = ntohl(tsval); 1589 pf_change_proto_a(m, &opt[2], 1590 &th->th_sum, 1591 htonl(tsval + 1592 src->scrub->pfss_ts_mod), 1593 0); 1594 copyback = 1; 1595 } 1596 1597 /* Modulate TS reply iff valid (!0) */ 1598 memcpy(&tsecr, &opt[6], 1599 sizeof(u_int32_t)); 1600 if (tsecr && dst->scrub && 1601 (dst->scrub->pfss_flags & 1602 PFSS_TIMESTAMP)) { 1603 tsecr = ntohl(tsecr) 1604 - dst->scrub->pfss_ts_mod; 1605 pf_change_proto_a(m, &opt[6], 1606 &th->th_sum, htonl(tsecr), 1607 0); 1608 copyback = 1; 1609 } 1610 got_ts = 1; 1611 } 1612 /* FALLTHROUGH */ 1613 default: 1614 hlen -= MAX(opt[1], 2); 1615 opt += MAX(opt[1], 2); 1616 break; 1617 } 1618 } 1619 if (copyback) { 1620 /* Copyback the options, caller copys back header */ 1621 *writeback = 1; 1622 m_copyback(m, off + sizeof(struct tcphdr), 1623 (th->th_off << 2) - sizeof(struct tcphdr), hdr + 1624 sizeof(struct tcphdr)); 1625 } 1626 } 1627 1628 1629 /* 1630 * Must invalidate PAWS checks on connections idle for too long. 1631 * The fastest allowed timestamp clock is 1ms. That turns out to 1632 * be about 24 days before it wraps. XXX Right now our lowerbound 1633 * TS echo check only works for the first 12 days of a connection 1634 * when the TS has exhausted half its 32bit space 1635 */ 1636 #define TS_MAX_IDLE (24*24*60*60) 1637 #define TS_MAX_CONN (12*24*60*60) /* XXX remove when better tsecr check */ 1638 1639 getmicrouptime(&uptime); 1640 if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) && 1641 (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE || 1642 time_uptime - state->creation > TS_MAX_CONN)) { 1643 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1644 DPFPRINTF(("src idled out of PAWS\n")); 1645 pf_print_state(state); 1646 printf("\n"); 1647 } 1648 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS) 1649 | PFSS_PAWS_IDLED; 1650 } 1651 if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) && 1652 uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) { 1653 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1654 DPFPRINTF(("dst idled out of PAWS\n")); 1655 pf_print_state(state); 1656 printf("\n"); 1657 } 1658 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS) 1659 | PFSS_PAWS_IDLED; 1660 } 1661 1662 if (got_ts && src->scrub && dst->scrub && 1663 (src->scrub->pfss_flags & PFSS_PAWS) && 1664 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1665 /* Validate that the timestamps are "in-window". 1666 * RFC1323 describes TCP Timestamp options that allow 1667 * measurement of RTT (round trip time) and PAWS 1668 * (protection against wrapped sequence numbers). PAWS 1669 * gives us a set of rules for rejecting packets on 1670 * long fat pipes (packets that were somehow delayed 1671 * in transit longer than the time it took to send the 1672 * full TCP sequence space of 4Gb). We can use these 1673 * rules and infer a few others that will let us treat 1674 * the 32bit timestamp and the 32bit echoed timestamp 1675 * as sequence numbers to prevent a blind attacker from 1676 * inserting packets into a connection. 1677 * 1678 * RFC1323 tells us: 1679 * - The timestamp on this packet must be greater than 1680 * or equal to the last value echoed by the other 1681 * endpoint. The RFC says those will be discarded 1682 * since it is a dup that has already been acked. 1683 * This gives us a lowerbound on the timestamp. 1684 * timestamp >= other last echoed timestamp 1685 * - The timestamp will be less than or equal to 1686 * the last timestamp plus the time between the 1687 * last packet and now. The RFC defines the max 1688 * clock rate as 1ms. We will allow clocks to be 1689 * up to 10% fast and will allow a total difference 1690 * or 30 seconds due to a route change. And this 1691 * gives us an upperbound on the timestamp. 1692 * timestamp <= last timestamp + max ticks 1693 * We have to be careful here. Windows will send an 1694 * initial timestamp of zero and then initialize it 1695 * to a random value after the 3whs; presumably to 1696 * avoid a DoS by having to call an expensive RNG 1697 * during a SYN flood. Proof MS has at least one 1698 * good security geek. 1699 * 1700 * - The TCP timestamp option must also echo the other 1701 * endpoints timestamp. The timestamp echoed is the 1702 * one carried on the earliest unacknowledged segment 1703 * on the left edge of the sequence window. The RFC 1704 * states that the host will reject any echoed 1705 * timestamps that were larger than any ever sent. 1706 * This gives us an upperbound on the TS echo. 1707 * tescr <= largest_tsval 1708 * - The lowerbound on the TS echo is a little more 1709 * tricky to determine. The other endpoint's echoed 1710 * values will not decrease. But there may be 1711 * network conditions that re-order packets and 1712 * cause our view of them to decrease. For now the 1713 * only lowerbound we can safely determine is that 1714 * the TS echo will never be less than the original 1715 * TS. XXX There is probably a better lowerbound. 1716 * Remove TS_MAX_CONN with better lowerbound check. 1717 * tescr >= other original TS 1718 * 1719 * It is also important to note that the fastest 1720 * timestamp clock of 1ms will wrap its 32bit space in 1721 * 24 days. So we just disable TS checking after 24 1722 * days of idle time. We actually must use a 12d 1723 * connection limit until we can come up with a better 1724 * lowerbound to the TS echo check. 1725 */ 1726 struct timeval delta_ts; 1727 int ts_fudge; 1728 1729 1730 /* 1731 * PFTM_TS_DIFF is how many seconds of leeway to allow 1732 * a host's timestamp. This can happen if the previous 1733 * packet got delayed in transit for much longer than 1734 * this packet. 1735 */ 1736 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0) 1737 ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF]; 1738 1739 /* Calculate max ticks since the last timestamp */ 1740 #define TS_MAXFREQ 1100 /* RFC max TS freq of 1Khz + 10% skew */ 1741 #define TS_MICROSECS 1000000 /* microseconds per second */ 1742 delta_ts = uptime; 1743 timevalsub(&delta_ts, &src->scrub->pfss_last); 1744 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ; 1745 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ); 1746 1747 if ((src->state >= TCPS_ESTABLISHED && 1748 dst->state >= TCPS_ESTABLISHED) && 1749 (SEQ_LT(tsval, dst->scrub->pfss_tsecr) || 1750 SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) || 1751 (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) || 1752 SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) { 1753 /* Bad RFC1323 implementation or an insertion attack. 1754 * 1755 * - Solaris 2.6 and 2.7 are known to send another ACK 1756 * after the FIN,FIN|ACK,ACK closing that carries 1757 * an old timestamp. 1758 */ 1759 1760 DPFPRINTF(("Timestamp failed %c%c%c%c\n", 1761 SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ', 1762 SEQ_GT(tsval, src->scrub->pfss_tsval + 1763 tsval_from_last) ? '1' : ' ', 1764 SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ', 1765 SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' ')); 1766 DPFPRINTF((" tsval: %u tsecr: %u +ticks: %u " 1767 "idle: %jus %lums\n", 1768 tsval, tsecr, tsval_from_last, 1769 (uintmax_t)delta_ts.tv_sec, 1770 delta_ts.tv_usec / 1000)); 1771 DPFPRINTF((" src->tsval: %u tsecr: %u\n", 1772 src->scrub->pfss_tsval, src->scrub->pfss_tsecr)); 1773 DPFPRINTF((" dst->tsval: %u tsecr: %u tsval0: %u" 1774 "\n", dst->scrub->pfss_tsval, 1775 dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0)); 1776 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1777 pf_print_state(state); 1778 pf_print_flags(th->th_flags); 1779 printf("\n"); 1780 } 1781 REASON_SET(reason, PFRES_TS); 1782 return (PF_DROP); 1783 } 1784 1785 /* XXX I'd really like to require tsecr but it's optional */ 1786 1787 } else if (!got_ts && (th->th_flags & TH_RST) == 0 && 1788 ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED) 1789 || pd->p_len > 0 || (th->th_flags & TH_SYN)) && 1790 src->scrub && dst->scrub && 1791 (src->scrub->pfss_flags & PFSS_PAWS) && 1792 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1793 /* Didn't send a timestamp. Timestamps aren't really useful 1794 * when: 1795 * - connection opening or closing (often not even sent). 1796 * but we must not let an attacker to put a FIN on a 1797 * data packet to sneak it through our ESTABLISHED check. 1798 * - on a TCP reset. RFC suggests not even looking at TS. 1799 * - on an empty ACK. The TS will not be echoed so it will 1800 * probably not help keep the RTT calculation in sync and 1801 * there isn't as much danger when the sequence numbers 1802 * got wrapped. So some stacks don't include TS on empty 1803 * ACKs :-( 1804 * 1805 * To minimize the disruption to mostly RFC1323 conformant 1806 * stacks, we will only require timestamps on data packets. 1807 * 1808 * And what do ya know, we cannot require timestamps on data 1809 * packets. There appear to be devices that do legitimate 1810 * TCP connection hijacking. There are HTTP devices that allow 1811 * a 3whs (with timestamps) and then buffer the HTTP request. 1812 * If the intermediate device has the HTTP response cache, it 1813 * will spoof the response but not bother timestamping its 1814 * packets. So we can look for the presence of a timestamp in 1815 * the first data packet and if there, require it in all future 1816 * packets. 1817 */ 1818 1819 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) { 1820 /* 1821 * Hey! Someone tried to sneak a packet in. Or the 1822 * stack changed its RFC1323 behavior?!?! 1823 */ 1824 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1825 DPFPRINTF(("Did not receive expected RFC1323 " 1826 "timestamp\n")); 1827 pf_print_state(state); 1828 pf_print_flags(th->th_flags); 1829 printf("\n"); 1830 } 1831 REASON_SET(reason, PFRES_TS); 1832 return (PF_DROP); 1833 } 1834 } 1835 1836 1837 /* 1838 * We will note if a host sends his data packets with or without 1839 * timestamps. And require all data packets to contain a timestamp 1840 * if the first does. PAWS implicitly requires that all data packets be 1841 * timestamped. But I think there are middle-man devices that hijack 1842 * TCP streams immediately after the 3whs and don't timestamp their 1843 * packets (seen in a WWW accelerator or cache). 1844 */ 1845 if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags & 1846 (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) { 1847 if (got_ts) 1848 src->scrub->pfss_flags |= PFSS_DATA_TS; 1849 else { 1850 src->scrub->pfss_flags |= PFSS_DATA_NOTS; 1851 if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub && 1852 (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) { 1853 /* Don't warn if other host rejected RFC1323 */ 1854 DPFPRINTF(("Broken RFC1323 stack did not " 1855 "timestamp data packet. Disabled PAWS " 1856 "security.\n")); 1857 pf_print_state(state); 1858 pf_print_flags(th->th_flags); 1859 printf("\n"); 1860 } 1861 } 1862 } 1863 1864 1865 /* 1866 * Update PAWS values 1867 */ 1868 if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags & 1869 (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) { 1870 getmicrouptime(&src->scrub->pfss_last); 1871 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) || 1872 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 1873 src->scrub->pfss_tsval = tsval; 1874 1875 if (tsecr) { 1876 if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) || 1877 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 1878 src->scrub->pfss_tsecr = tsecr; 1879 1880 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 && 1881 (SEQ_LT(tsval, src->scrub->pfss_tsval0) || 1882 src->scrub->pfss_tsval0 == 0)) { 1883 /* tsval0 MUST be the lowest timestamp */ 1884 src->scrub->pfss_tsval0 = tsval; 1885 } 1886 1887 /* Only fully initialized after a TS gets echoed */ 1888 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0) 1889 src->scrub->pfss_flags |= PFSS_PAWS; 1890 } 1891 } 1892 1893 /* I have a dream.... TCP segment reassembly.... */ 1894 return (0); 1895 } 1896 1897 static int 1898 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th, 1899 int off, sa_family_t af) 1900 { 1901 u_int16_t *mss; 1902 int thoff; 1903 int opt, cnt, optlen = 0; 1904 int rewrite = 0; 1905 u_char opts[TCP_MAXOLEN]; 1906 u_char *optp = opts; 1907 1908 thoff = th->th_off << 2; 1909 cnt = thoff - sizeof(struct tcphdr); 1910 1911 if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt, 1912 NULL, NULL, af)) 1913 return (rewrite); 1914 1915 for (; cnt > 0; cnt -= optlen, optp += optlen) { 1916 opt = optp[0]; 1917 if (opt == TCPOPT_EOL) 1918 break; 1919 if (opt == TCPOPT_NOP) 1920 optlen = 1; 1921 else { 1922 if (cnt < 2) 1923 break; 1924 optlen = optp[1]; 1925 if (optlen < 2 || optlen > cnt) 1926 break; 1927 } 1928 switch (opt) { 1929 case TCPOPT_MAXSEG: 1930 mss = (u_int16_t *)(optp + 2); 1931 if ((ntohs(*mss)) > r->max_mss) { 1932 th->th_sum = pf_proto_cksum_fixup(m, 1933 th->th_sum, *mss, htons(r->max_mss), 0); 1934 *mss = htons(r->max_mss); 1935 rewrite = 1; 1936 } 1937 break; 1938 default: 1939 break; 1940 } 1941 } 1942 1943 if (rewrite) 1944 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts); 1945 1946 return (rewrite); 1947 } 1948 1949 #ifdef INET 1950 static void 1951 pf_scrub_ip(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos) 1952 { 1953 struct mbuf *m = *m0; 1954 struct ip *h = mtod(m, struct ip *); 1955 1956 /* Clear IP_DF if no-df was requested */ 1957 if (flags & PFRULE_NODF && h->ip_off & htons(IP_DF)) { 1958 u_int16_t ip_off = h->ip_off; 1959 1960 h->ip_off &= htons(~IP_DF); 1961 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1962 } 1963 1964 /* Enforce a minimum ttl, may cause endless packet loops */ 1965 if (min_ttl && h->ip_ttl < min_ttl) { 1966 u_int16_t ip_ttl = h->ip_ttl; 1967 1968 h->ip_ttl = min_ttl; 1969 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0); 1970 } 1971 1972 /* Enforce tos */ 1973 if (flags & PFRULE_SET_TOS) { 1974 u_int16_t ov, nv; 1975 1976 ov = *(u_int16_t *)h; 1977 h->ip_tos = tos | (h->ip_tos & IPTOS_ECN_MASK); 1978 nv = *(u_int16_t *)h; 1979 1980 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0); 1981 } 1982 1983 /* random-id, but not for fragments */ 1984 if (flags & PFRULE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) { 1985 uint16_t ip_id = h->ip_id; 1986 1987 ip_fillid(h); 1988 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0); 1989 } 1990 } 1991 #endif /* INET */ 1992 1993 #ifdef INET6 1994 static void 1995 pf_scrub_ip6(struct mbuf **m0, u_int8_t min_ttl) 1996 { 1997 struct mbuf *m = *m0; 1998 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1999 2000 /* Enforce a minimum ttl, may cause endless packet loops */ 2001 if (min_ttl && h->ip6_hlim < min_ttl) 2002 h->ip6_hlim = min_ttl; 2003 } 2004 #endif 2005