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 extoff = frent->fe_extoff; 840 maxlen = frag->fr_maxlen; 841 frag_id = frag->fr_id; 842 frent = TAILQ_FIRST(&frag->fr_queue); 843 KASSERT(frent != NULL, ("frent != NULL")); 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_opt_jumbo jumbo; 1143 struct ip6_frag frag; 1144 u_int32_t jumbolen = 0, plen; 1145 int optend; 1146 int ooff; 1147 u_int8_t proto; 1148 int terminal; 1149 1150 PF_RULES_RASSERT(); 1151 1152 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1153 while (r != NULL) { 1154 r->evaluations++; 1155 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1156 r = r->skip[PF_SKIP_IFP].ptr; 1157 else if (r->direction && r->direction != dir) 1158 r = r->skip[PF_SKIP_DIR].ptr; 1159 else if (r->af && r->af != AF_INET6) 1160 r = r->skip[PF_SKIP_AF].ptr; 1161 #if 0 /* header chain! */ 1162 else if (r->proto && r->proto != h->ip6_nxt) 1163 r = r->skip[PF_SKIP_PROTO].ptr; 1164 #endif 1165 else if (PF_MISMATCHAW(&r->src.addr, 1166 (struct pf_addr *)&h->ip6_src, AF_INET6, 1167 r->src.neg, kif, M_GETFIB(m))) 1168 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1169 else if (PF_MISMATCHAW(&r->dst.addr, 1170 (struct pf_addr *)&h->ip6_dst, AF_INET6, 1171 r->dst.neg, NULL, M_GETFIB(m))) 1172 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1173 else 1174 break; 1175 } 1176 1177 if (r == NULL || r->action == PF_NOSCRUB) 1178 return (PF_PASS); 1179 else { 1180 r->packets[dir == PF_OUT]++; 1181 r->bytes[dir == PF_OUT] += pd->tot_len; 1182 } 1183 1184 /* Check for illegal packets */ 1185 if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len) 1186 goto drop; 1187 1188 extoff = 0; 1189 off = sizeof(struct ip6_hdr); 1190 proto = h->ip6_nxt; 1191 terminal = 0; 1192 do { 1193 switch (proto) { 1194 case IPPROTO_FRAGMENT: 1195 goto fragment; 1196 break; 1197 case IPPROTO_AH: 1198 case IPPROTO_ROUTING: 1199 case IPPROTO_DSTOPTS: 1200 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1201 NULL, AF_INET6)) 1202 goto shortpkt; 1203 extoff = off; 1204 if (proto == IPPROTO_AH) 1205 off += (ext.ip6e_len + 2) * 4; 1206 else 1207 off += (ext.ip6e_len + 1) * 8; 1208 proto = ext.ip6e_nxt; 1209 break; 1210 case IPPROTO_HOPOPTS: 1211 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1212 NULL, AF_INET6)) 1213 goto shortpkt; 1214 extoff = off; 1215 optend = off + (ext.ip6e_len + 1) * 8; 1216 ooff = off + sizeof(ext); 1217 do { 1218 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type, 1219 sizeof(opt.ip6o_type), NULL, NULL, 1220 AF_INET6)) 1221 goto shortpkt; 1222 if (opt.ip6o_type == IP6OPT_PAD1) { 1223 ooff++; 1224 continue; 1225 } 1226 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt), 1227 NULL, NULL, AF_INET6)) 1228 goto shortpkt; 1229 if (ooff + sizeof(opt) + opt.ip6o_len > optend) 1230 goto drop; 1231 switch (opt.ip6o_type) { 1232 case IP6OPT_JUMBO: 1233 if (h->ip6_plen != 0) 1234 goto drop; 1235 if (!pf_pull_hdr(m, ooff, &jumbo, 1236 sizeof(jumbo), NULL, NULL, 1237 AF_INET6)) 1238 goto shortpkt; 1239 memcpy(&jumbolen, jumbo.ip6oj_jumbo_len, 1240 sizeof(jumbolen)); 1241 jumbolen = ntohl(jumbolen); 1242 if (jumbolen <= IPV6_MAXPACKET) 1243 goto drop; 1244 if (sizeof(struct ip6_hdr) + jumbolen != 1245 m->m_pkthdr.len) 1246 goto drop; 1247 break; 1248 default: 1249 break; 1250 } 1251 ooff += sizeof(opt) + opt.ip6o_len; 1252 } while (ooff < optend); 1253 1254 off = optend; 1255 proto = ext.ip6e_nxt; 1256 break; 1257 default: 1258 terminal = 1; 1259 break; 1260 } 1261 } while (!terminal); 1262 1263 /* jumbo payload option must be present, or plen > 0 */ 1264 if (ntohs(h->ip6_plen) == 0) 1265 plen = jumbolen; 1266 else 1267 plen = ntohs(h->ip6_plen); 1268 if (plen == 0) 1269 goto drop; 1270 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1271 goto shortpkt; 1272 1273 pf_scrub_ip6(&m, r->min_ttl); 1274 1275 return (PF_PASS); 1276 1277 fragment: 1278 /* Jumbo payload packets cannot be fragmented. */ 1279 plen = ntohs(h->ip6_plen); 1280 if (plen == 0 || jumbolen) 1281 goto drop; 1282 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1283 goto shortpkt; 1284 1285 if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6)) 1286 goto shortpkt; 1287 1288 /* Offset now points to data portion. */ 1289 off += sizeof(frag); 1290 1291 /* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */ 1292 if (pf_reassemble6(m0, h, &frag, off, extoff, reason) != PF_PASS) 1293 return (PF_DROP); 1294 m = *m0; 1295 if (m == NULL) 1296 return (PF_DROP); 1297 1298 pd->flags |= PFDESC_IP_REAS; 1299 return (PF_PASS); 1300 1301 shortpkt: 1302 REASON_SET(reason, PFRES_SHORT); 1303 if (r != NULL && r->log) 1304 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd, 1305 1); 1306 return (PF_DROP); 1307 1308 drop: 1309 REASON_SET(reason, PFRES_NORM); 1310 if (r != NULL && r->log) 1311 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd, 1312 1); 1313 return (PF_DROP); 1314 } 1315 #endif /* INET6 */ 1316 1317 int 1318 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff, 1319 int off, void *h, struct pf_pdesc *pd) 1320 { 1321 struct pf_rule *r, *rm = NULL; 1322 struct tcphdr *th = pd->hdr.tcp; 1323 int rewrite = 0; 1324 u_short reason; 1325 u_int8_t flags; 1326 sa_family_t af = pd->af; 1327 1328 PF_RULES_RASSERT(); 1329 1330 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1331 while (r != NULL) { 1332 r->evaluations++; 1333 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1334 r = r->skip[PF_SKIP_IFP].ptr; 1335 else if (r->direction && r->direction != dir) 1336 r = r->skip[PF_SKIP_DIR].ptr; 1337 else if (r->af && r->af != af) 1338 r = r->skip[PF_SKIP_AF].ptr; 1339 else if (r->proto && r->proto != pd->proto) 1340 r = r->skip[PF_SKIP_PROTO].ptr; 1341 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, 1342 r->src.neg, kif, M_GETFIB(m))) 1343 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1344 else if (r->src.port_op && !pf_match_port(r->src.port_op, 1345 r->src.port[0], r->src.port[1], th->th_sport)) 1346 r = r->skip[PF_SKIP_SRC_PORT].ptr; 1347 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, 1348 r->dst.neg, NULL, M_GETFIB(m))) 1349 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1350 else if (r->dst.port_op && !pf_match_port(r->dst.port_op, 1351 r->dst.port[0], r->dst.port[1], th->th_dport)) 1352 r = r->skip[PF_SKIP_DST_PORT].ptr; 1353 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match( 1354 pf_osfp_fingerprint(pd, m, off, th), 1355 r->os_fingerprint)) 1356 r = TAILQ_NEXT(r, entries); 1357 else { 1358 rm = r; 1359 break; 1360 } 1361 } 1362 1363 if (rm == NULL || rm->action == PF_NOSCRUB) 1364 return (PF_PASS); 1365 else { 1366 r->packets[dir == PF_OUT]++; 1367 r->bytes[dir == PF_OUT] += pd->tot_len; 1368 } 1369 1370 if (rm->rule_flag & PFRULE_REASSEMBLE_TCP) 1371 pd->flags |= PFDESC_TCP_NORM; 1372 1373 flags = th->th_flags; 1374 if (flags & TH_SYN) { 1375 /* Illegal packet */ 1376 if (flags & TH_RST) 1377 goto tcp_drop; 1378 1379 if (flags & TH_FIN) 1380 goto tcp_drop; 1381 } else { 1382 /* Illegal packet */ 1383 if (!(flags & (TH_ACK|TH_RST))) 1384 goto tcp_drop; 1385 } 1386 1387 if (!(flags & TH_ACK)) { 1388 /* These flags are only valid if ACK is set */ 1389 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG)) 1390 goto tcp_drop; 1391 } 1392 1393 /* Check for illegal header length */ 1394 if (th->th_off < (sizeof(struct tcphdr) >> 2)) 1395 goto tcp_drop; 1396 1397 /* If flags changed, or reserved data set, then adjust */ 1398 if (flags != th->th_flags || th->th_x2 != 0) { 1399 u_int16_t ov, nv; 1400 1401 ov = *(u_int16_t *)(&th->th_ack + 1); 1402 th->th_flags = flags; 1403 th->th_x2 = 0; 1404 nv = *(u_int16_t *)(&th->th_ack + 1); 1405 1406 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, ov, nv, 0); 1407 rewrite = 1; 1408 } 1409 1410 /* Remove urgent pointer, if TH_URG is not set */ 1411 if (!(flags & TH_URG) && th->th_urp) { 1412 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, th->th_urp, 1413 0, 0); 1414 th->th_urp = 0; 1415 rewrite = 1; 1416 } 1417 1418 /* Process options */ 1419 if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af)) 1420 rewrite = 1; 1421 1422 /* copy back packet headers if we sanitized */ 1423 if (rewrite) 1424 m_copyback(m, off, sizeof(*th), (caddr_t)th); 1425 1426 return (PF_PASS); 1427 1428 tcp_drop: 1429 REASON_SET(&reason, PFRES_NORM); 1430 if (rm != NULL && r->log) 1431 PFLOG_PACKET(kif, m, AF_INET, dir, reason, r, NULL, NULL, pd, 1432 1); 1433 return (PF_DROP); 1434 } 1435 1436 int 1437 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd, 1438 struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst) 1439 { 1440 u_int32_t tsval, tsecr; 1441 u_int8_t hdr[60]; 1442 u_int8_t *opt; 1443 1444 KASSERT((src->scrub == NULL), 1445 ("pf_normalize_tcp_init: src->scrub != NULL")); 1446 1447 src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT); 1448 if (src->scrub == NULL) 1449 return (1); 1450 1451 switch (pd->af) { 1452 #ifdef INET 1453 case AF_INET: { 1454 struct ip *h = mtod(m, struct ip *); 1455 src->scrub->pfss_ttl = h->ip_ttl; 1456 break; 1457 } 1458 #endif /* INET */ 1459 #ifdef INET6 1460 case AF_INET6: { 1461 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1462 src->scrub->pfss_ttl = h->ip6_hlim; 1463 break; 1464 } 1465 #endif /* INET6 */ 1466 } 1467 1468 1469 /* 1470 * All normalizations below are only begun if we see the start of 1471 * the connections. They must all set an enabled bit in pfss_flags 1472 */ 1473 if ((th->th_flags & TH_SYN) == 0) 1474 return (0); 1475 1476 1477 if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub && 1478 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1479 /* Diddle with TCP options */ 1480 int hlen; 1481 opt = hdr + sizeof(struct tcphdr); 1482 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1483 while (hlen >= TCPOLEN_TIMESTAMP) { 1484 switch (*opt) { 1485 case TCPOPT_EOL: /* FALLTHROUGH */ 1486 case TCPOPT_NOP: 1487 opt++; 1488 hlen--; 1489 break; 1490 case TCPOPT_TIMESTAMP: 1491 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1492 src->scrub->pfss_flags |= 1493 PFSS_TIMESTAMP; 1494 src->scrub->pfss_ts_mod = 1495 htonl(arc4random()); 1496 1497 /* note PFSS_PAWS not set yet */ 1498 memcpy(&tsval, &opt[2], 1499 sizeof(u_int32_t)); 1500 memcpy(&tsecr, &opt[6], 1501 sizeof(u_int32_t)); 1502 src->scrub->pfss_tsval0 = ntohl(tsval); 1503 src->scrub->pfss_tsval = ntohl(tsval); 1504 src->scrub->pfss_tsecr = ntohl(tsecr); 1505 getmicrouptime(&src->scrub->pfss_last); 1506 } 1507 /* FALLTHROUGH */ 1508 default: 1509 hlen -= MAX(opt[1], 2); 1510 opt += MAX(opt[1], 2); 1511 break; 1512 } 1513 } 1514 } 1515 1516 return (0); 1517 } 1518 1519 void 1520 pf_normalize_tcp_cleanup(struct pf_state *state) 1521 { 1522 if (state->src.scrub) 1523 uma_zfree(V_pf_state_scrub_z, state->src.scrub); 1524 if (state->dst.scrub) 1525 uma_zfree(V_pf_state_scrub_z, state->dst.scrub); 1526 1527 /* Someday... flush the TCP segment reassembly descriptors. */ 1528 } 1529 1530 int 1531 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd, 1532 u_short *reason, struct tcphdr *th, struct pf_state *state, 1533 struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback) 1534 { 1535 struct timeval uptime; 1536 u_int32_t tsval, tsecr; 1537 u_int tsval_from_last; 1538 u_int8_t hdr[60]; 1539 u_int8_t *opt; 1540 int copyback = 0; 1541 int got_ts = 0; 1542 1543 KASSERT((src->scrub || dst->scrub), 1544 ("%s: src->scrub && dst->scrub!", __func__)); 1545 1546 /* 1547 * Enforce the minimum TTL seen for this connection. Negate a common 1548 * technique to evade an intrusion detection system and confuse 1549 * firewall state code. 1550 */ 1551 switch (pd->af) { 1552 #ifdef INET 1553 case AF_INET: { 1554 if (src->scrub) { 1555 struct ip *h = mtod(m, struct ip *); 1556 if (h->ip_ttl > src->scrub->pfss_ttl) 1557 src->scrub->pfss_ttl = h->ip_ttl; 1558 h->ip_ttl = src->scrub->pfss_ttl; 1559 } 1560 break; 1561 } 1562 #endif /* INET */ 1563 #ifdef INET6 1564 case AF_INET6: { 1565 if (src->scrub) { 1566 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1567 if (h->ip6_hlim > src->scrub->pfss_ttl) 1568 src->scrub->pfss_ttl = h->ip6_hlim; 1569 h->ip6_hlim = src->scrub->pfss_ttl; 1570 } 1571 break; 1572 } 1573 #endif /* INET6 */ 1574 } 1575 1576 if (th->th_off > (sizeof(struct tcphdr) >> 2) && 1577 ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) || 1578 (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) && 1579 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1580 /* Diddle with TCP options */ 1581 int hlen; 1582 opt = hdr + sizeof(struct tcphdr); 1583 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1584 while (hlen >= TCPOLEN_TIMESTAMP) { 1585 switch (*opt) { 1586 case TCPOPT_EOL: /* FALLTHROUGH */ 1587 case TCPOPT_NOP: 1588 opt++; 1589 hlen--; 1590 break; 1591 case TCPOPT_TIMESTAMP: 1592 /* Modulate the timestamps. Can be used for 1593 * NAT detection, OS uptime determination or 1594 * reboot detection. 1595 */ 1596 1597 if (got_ts) { 1598 /* Huh? Multiple timestamps!? */ 1599 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1600 DPFPRINTF(("multiple TS??")); 1601 pf_print_state(state); 1602 printf("\n"); 1603 } 1604 REASON_SET(reason, PFRES_TS); 1605 return (PF_DROP); 1606 } 1607 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1608 memcpy(&tsval, &opt[2], 1609 sizeof(u_int32_t)); 1610 if (tsval && src->scrub && 1611 (src->scrub->pfss_flags & 1612 PFSS_TIMESTAMP)) { 1613 tsval = ntohl(tsval); 1614 pf_change_proto_a(m, &opt[2], 1615 &th->th_sum, 1616 htonl(tsval + 1617 src->scrub->pfss_ts_mod), 1618 0); 1619 copyback = 1; 1620 } 1621 1622 /* Modulate TS reply iff valid (!0) */ 1623 memcpy(&tsecr, &opt[6], 1624 sizeof(u_int32_t)); 1625 if (tsecr && dst->scrub && 1626 (dst->scrub->pfss_flags & 1627 PFSS_TIMESTAMP)) { 1628 tsecr = ntohl(tsecr) 1629 - dst->scrub->pfss_ts_mod; 1630 pf_change_proto_a(m, &opt[6], 1631 &th->th_sum, htonl(tsecr), 1632 0); 1633 copyback = 1; 1634 } 1635 got_ts = 1; 1636 } 1637 /* FALLTHROUGH */ 1638 default: 1639 hlen -= MAX(opt[1], 2); 1640 opt += MAX(opt[1], 2); 1641 break; 1642 } 1643 } 1644 if (copyback) { 1645 /* Copyback the options, caller copys back header */ 1646 *writeback = 1; 1647 m_copyback(m, off + sizeof(struct tcphdr), 1648 (th->th_off << 2) - sizeof(struct tcphdr), hdr + 1649 sizeof(struct tcphdr)); 1650 } 1651 } 1652 1653 1654 /* 1655 * Must invalidate PAWS checks on connections idle for too long. 1656 * The fastest allowed timestamp clock is 1ms. That turns out to 1657 * be about 24 days before it wraps. XXX Right now our lowerbound 1658 * TS echo check only works for the first 12 days of a connection 1659 * when the TS has exhausted half its 32bit space 1660 */ 1661 #define TS_MAX_IDLE (24*24*60*60) 1662 #define TS_MAX_CONN (12*24*60*60) /* XXX remove when better tsecr check */ 1663 1664 getmicrouptime(&uptime); 1665 if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) && 1666 (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE || 1667 time_uptime - state->creation > TS_MAX_CONN)) { 1668 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1669 DPFPRINTF(("src idled out of PAWS\n")); 1670 pf_print_state(state); 1671 printf("\n"); 1672 } 1673 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS) 1674 | PFSS_PAWS_IDLED; 1675 } 1676 if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) && 1677 uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) { 1678 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1679 DPFPRINTF(("dst idled out of PAWS\n")); 1680 pf_print_state(state); 1681 printf("\n"); 1682 } 1683 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS) 1684 | PFSS_PAWS_IDLED; 1685 } 1686 1687 if (got_ts && src->scrub && dst->scrub && 1688 (src->scrub->pfss_flags & PFSS_PAWS) && 1689 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1690 /* Validate that the timestamps are "in-window". 1691 * RFC1323 describes TCP Timestamp options that allow 1692 * measurement of RTT (round trip time) and PAWS 1693 * (protection against wrapped sequence numbers). PAWS 1694 * gives us a set of rules for rejecting packets on 1695 * long fat pipes (packets that were somehow delayed 1696 * in transit longer than the time it took to send the 1697 * full TCP sequence space of 4Gb). We can use these 1698 * rules and infer a few others that will let us treat 1699 * the 32bit timestamp and the 32bit echoed timestamp 1700 * as sequence numbers to prevent a blind attacker from 1701 * inserting packets into a connection. 1702 * 1703 * RFC1323 tells us: 1704 * - The timestamp on this packet must be greater than 1705 * or equal to the last value echoed by the other 1706 * endpoint. The RFC says those will be discarded 1707 * since it is a dup that has already been acked. 1708 * This gives us a lowerbound on the timestamp. 1709 * timestamp >= other last echoed timestamp 1710 * - The timestamp will be less than or equal to 1711 * the last timestamp plus the time between the 1712 * last packet and now. The RFC defines the max 1713 * clock rate as 1ms. We will allow clocks to be 1714 * up to 10% fast and will allow a total difference 1715 * or 30 seconds due to a route change. And this 1716 * gives us an upperbound on the timestamp. 1717 * timestamp <= last timestamp + max ticks 1718 * We have to be careful here. Windows will send an 1719 * initial timestamp of zero and then initialize it 1720 * to a random value after the 3whs; presumably to 1721 * avoid a DoS by having to call an expensive RNG 1722 * during a SYN flood. Proof MS has at least one 1723 * good security geek. 1724 * 1725 * - The TCP timestamp option must also echo the other 1726 * endpoints timestamp. The timestamp echoed is the 1727 * one carried on the earliest unacknowledged segment 1728 * on the left edge of the sequence window. The RFC 1729 * states that the host will reject any echoed 1730 * timestamps that were larger than any ever sent. 1731 * This gives us an upperbound on the TS echo. 1732 * tescr <= largest_tsval 1733 * - The lowerbound on the TS echo is a little more 1734 * tricky to determine. The other endpoint's echoed 1735 * values will not decrease. But there may be 1736 * network conditions that re-order packets and 1737 * cause our view of them to decrease. For now the 1738 * only lowerbound we can safely determine is that 1739 * the TS echo will never be less than the original 1740 * TS. XXX There is probably a better lowerbound. 1741 * Remove TS_MAX_CONN with better lowerbound check. 1742 * tescr >= other original TS 1743 * 1744 * It is also important to note that the fastest 1745 * timestamp clock of 1ms will wrap its 32bit space in 1746 * 24 days. So we just disable TS checking after 24 1747 * days of idle time. We actually must use a 12d 1748 * connection limit until we can come up with a better 1749 * lowerbound to the TS echo check. 1750 */ 1751 struct timeval delta_ts; 1752 int ts_fudge; 1753 1754 1755 /* 1756 * PFTM_TS_DIFF is how many seconds of leeway to allow 1757 * a host's timestamp. This can happen if the previous 1758 * packet got delayed in transit for much longer than 1759 * this packet. 1760 */ 1761 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0) 1762 ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF]; 1763 1764 /* Calculate max ticks since the last timestamp */ 1765 #define TS_MAXFREQ 1100 /* RFC max TS freq of 1Khz + 10% skew */ 1766 #define TS_MICROSECS 1000000 /* microseconds per second */ 1767 delta_ts = uptime; 1768 timevalsub(&delta_ts, &src->scrub->pfss_last); 1769 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ; 1770 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ); 1771 1772 if ((src->state >= TCPS_ESTABLISHED && 1773 dst->state >= TCPS_ESTABLISHED) && 1774 (SEQ_LT(tsval, dst->scrub->pfss_tsecr) || 1775 SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) || 1776 (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) || 1777 SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) { 1778 /* Bad RFC1323 implementation or an insertion attack. 1779 * 1780 * - Solaris 2.6 and 2.7 are known to send another ACK 1781 * after the FIN,FIN|ACK,ACK closing that carries 1782 * an old timestamp. 1783 */ 1784 1785 DPFPRINTF(("Timestamp failed %c%c%c%c\n", 1786 SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ', 1787 SEQ_GT(tsval, src->scrub->pfss_tsval + 1788 tsval_from_last) ? '1' : ' ', 1789 SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ', 1790 SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' ')); 1791 DPFPRINTF((" tsval: %u tsecr: %u +ticks: %u " 1792 "idle: %jus %lums\n", 1793 tsval, tsecr, tsval_from_last, 1794 (uintmax_t)delta_ts.tv_sec, 1795 delta_ts.tv_usec / 1000)); 1796 DPFPRINTF((" src->tsval: %u tsecr: %u\n", 1797 src->scrub->pfss_tsval, src->scrub->pfss_tsecr)); 1798 DPFPRINTF((" dst->tsval: %u tsecr: %u tsval0: %u" 1799 "\n", dst->scrub->pfss_tsval, 1800 dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0)); 1801 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1802 pf_print_state(state); 1803 pf_print_flags(th->th_flags); 1804 printf("\n"); 1805 } 1806 REASON_SET(reason, PFRES_TS); 1807 return (PF_DROP); 1808 } 1809 1810 /* XXX I'd really like to require tsecr but it's optional */ 1811 1812 } else if (!got_ts && (th->th_flags & TH_RST) == 0 && 1813 ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED) 1814 || pd->p_len > 0 || (th->th_flags & TH_SYN)) && 1815 src->scrub && dst->scrub && 1816 (src->scrub->pfss_flags & PFSS_PAWS) && 1817 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1818 /* Didn't send a timestamp. Timestamps aren't really useful 1819 * when: 1820 * - connection opening or closing (often not even sent). 1821 * but we must not let an attacker to put a FIN on a 1822 * data packet to sneak it through our ESTABLISHED check. 1823 * - on a TCP reset. RFC suggests not even looking at TS. 1824 * - on an empty ACK. The TS will not be echoed so it will 1825 * probably not help keep the RTT calculation in sync and 1826 * there isn't as much danger when the sequence numbers 1827 * got wrapped. So some stacks don't include TS on empty 1828 * ACKs :-( 1829 * 1830 * To minimize the disruption to mostly RFC1323 conformant 1831 * stacks, we will only require timestamps on data packets. 1832 * 1833 * And what do ya know, we cannot require timestamps on data 1834 * packets. There appear to be devices that do legitimate 1835 * TCP connection hijacking. There are HTTP devices that allow 1836 * a 3whs (with timestamps) and then buffer the HTTP request. 1837 * If the intermediate device has the HTTP response cache, it 1838 * will spoof the response but not bother timestamping its 1839 * packets. So we can look for the presence of a timestamp in 1840 * the first data packet and if there, require it in all future 1841 * packets. 1842 */ 1843 1844 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) { 1845 /* 1846 * Hey! Someone tried to sneak a packet in. Or the 1847 * stack changed its RFC1323 behavior?!?! 1848 */ 1849 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1850 DPFPRINTF(("Did not receive expected RFC1323 " 1851 "timestamp\n")); 1852 pf_print_state(state); 1853 pf_print_flags(th->th_flags); 1854 printf("\n"); 1855 } 1856 REASON_SET(reason, PFRES_TS); 1857 return (PF_DROP); 1858 } 1859 } 1860 1861 1862 /* 1863 * We will note if a host sends his data packets with or without 1864 * timestamps. And require all data packets to contain a timestamp 1865 * if the first does. PAWS implicitly requires that all data packets be 1866 * timestamped. But I think there are middle-man devices that hijack 1867 * TCP streams immediately after the 3whs and don't timestamp their 1868 * packets (seen in a WWW accelerator or cache). 1869 */ 1870 if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags & 1871 (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) { 1872 if (got_ts) 1873 src->scrub->pfss_flags |= PFSS_DATA_TS; 1874 else { 1875 src->scrub->pfss_flags |= PFSS_DATA_NOTS; 1876 if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub && 1877 (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) { 1878 /* Don't warn if other host rejected RFC1323 */ 1879 DPFPRINTF(("Broken RFC1323 stack did not " 1880 "timestamp data packet. Disabled PAWS " 1881 "security.\n")); 1882 pf_print_state(state); 1883 pf_print_flags(th->th_flags); 1884 printf("\n"); 1885 } 1886 } 1887 } 1888 1889 1890 /* 1891 * Update PAWS values 1892 */ 1893 if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags & 1894 (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) { 1895 getmicrouptime(&src->scrub->pfss_last); 1896 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) || 1897 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 1898 src->scrub->pfss_tsval = tsval; 1899 1900 if (tsecr) { 1901 if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) || 1902 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 1903 src->scrub->pfss_tsecr = tsecr; 1904 1905 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 && 1906 (SEQ_LT(tsval, src->scrub->pfss_tsval0) || 1907 src->scrub->pfss_tsval0 == 0)) { 1908 /* tsval0 MUST be the lowest timestamp */ 1909 src->scrub->pfss_tsval0 = tsval; 1910 } 1911 1912 /* Only fully initialized after a TS gets echoed */ 1913 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0) 1914 src->scrub->pfss_flags |= PFSS_PAWS; 1915 } 1916 } 1917 1918 /* I have a dream.... TCP segment reassembly.... */ 1919 return (0); 1920 } 1921 1922 static int 1923 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th, 1924 int off, sa_family_t af) 1925 { 1926 u_int16_t *mss; 1927 int thoff; 1928 int opt, cnt, optlen = 0; 1929 int rewrite = 0; 1930 u_char opts[TCP_MAXOLEN]; 1931 u_char *optp = opts; 1932 1933 thoff = th->th_off << 2; 1934 cnt = thoff - sizeof(struct tcphdr); 1935 1936 if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt, 1937 NULL, NULL, af)) 1938 return (rewrite); 1939 1940 for (; cnt > 0; cnt -= optlen, optp += optlen) { 1941 opt = optp[0]; 1942 if (opt == TCPOPT_EOL) 1943 break; 1944 if (opt == TCPOPT_NOP) 1945 optlen = 1; 1946 else { 1947 if (cnt < 2) 1948 break; 1949 optlen = optp[1]; 1950 if (optlen < 2 || optlen > cnt) 1951 break; 1952 } 1953 switch (opt) { 1954 case TCPOPT_MAXSEG: 1955 mss = (u_int16_t *)(optp + 2); 1956 if ((ntohs(*mss)) > r->max_mss) { 1957 th->th_sum = pf_proto_cksum_fixup(m, 1958 th->th_sum, *mss, htons(r->max_mss), 0); 1959 *mss = htons(r->max_mss); 1960 rewrite = 1; 1961 } 1962 break; 1963 default: 1964 break; 1965 } 1966 } 1967 1968 if (rewrite) 1969 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts); 1970 1971 return (rewrite); 1972 } 1973 1974 #ifdef INET 1975 static void 1976 pf_scrub_ip(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos) 1977 { 1978 struct mbuf *m = *m0; 1979 struct ip *h = mtod(m, struct ip *); 1980 1981 /* Clear IP_DF if no-df was requested */ 1982 if (flags & PFRULE_NODF && h->ip_off & htons(IP_DF)) { 1983 u_int16_t ip_off = h->ip_off; 1984 1985 h->ip_off &= htons(~IP_DF); 1986 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1987 } 1988 1989 /* Enforce a minimum ttl, may cause endless packet loops */ 1990 if (min_ttl && h->ip_ttl < min_ttl) { 1991 u_int16_t ip_ttl = h->ip_ttl; 1992 1993 h->ip_ttl = min_ttl; 1994 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0); 1995 } 1996 1997 /* Enforce tos */ 1998 if (flags & PFRULE_SET_TOS) { 1999 u_int16_t ov, nv; 2000 2001 ov = *(u_int16_t *)h; 2002 h->ip_tos = tos | (h->ip_tos & IPTOS_ECN_MASK); 2003 nv = *(u_int16_t *)h; 2004 2005 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0); 2006 } 2007 2008 /* random-id, but not for fragments */ 2009 if (flags & PFRULE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) { 2010 uint16_t ip_id = h->ip_id; 2011 2012 ip_fillid(h); 2013 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0); 2014 } 2015 } 2016 #endif /* INET */ 2017 2018 #ifdef INET6 2019 static void 2020 pf_scrub_ip6(struct mbuf **m0, u_int8_t min_ttl) 2021 { 2022 struct mbuf *m = *m0; 2023 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 2024 2025 /* Enforce a minimum ttl, may cause endless packet loops */ 2026 if (min_ttl && h->ip6_hlim < min_ttl) 2027 h->ip6_hlim = min_ttl; 2028 } 2029 #endif 2030