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 #include "opt_inet.h" 33 #include "opt_inet6.h" 34 #include "opt_pf.h" 35 36 #include <sys/param.h> 37 #include <sys/kernel.h> 38 #include <sys/lock.h> 39 #include <sys/mbuf.h> 40 #include <sys/mutex.h> 41 #include <sys/refcount.h> 42 #include <sys/socket.h> 43 44 #include <net/if.h> 45 #include <net/if_var.h> 46 #include <net/if_private.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/in6_var.h> 55 #include <netinet6/nd6.h> 56 #include <netinet6/ip6_var.h> 57 #include <netinet6/scope6_var.h> 58 #include <netinet/tcp.h> 59 #include <netinet/tcp_fsm.h> 60 #include <netinet/tcp_seq.h> 61 #include <netinet/sctp_constants.h> 62 #include <netinet/sctp_header.h> 63 64 #ifdef INET6 65 #include <netinet/ip6.h> 66 #endif /* INET6 */ 67 68 struct pf_frent { 69 TAILQ_ENTRY(pf_frent) fr_next; 70 struct mbuf *fe_m; 71 uint16_t fe_hdrlen; /* ipv4 header length with ip options 72 ipv6, extension, fragment header */ 73 uint16_t fe_extoff; /* last extension header offset or 0 */ 74 uint16_t fe_len; /* fragment length */ 75 uint16_t fe_off; /* fragment offset */ 76 uint16_t fe_mff; /* more fragment flag */ 77 }; 78 79 struct pf_fragment_cmp { 80 struct pf_addr frc_src; 81 struct pf_addr frc_dst; 82 uint32_t frc_id; 83 sa_family_t frc_af; 84 uint8_t frc_proto; 85 }; 86 87 struct pf_fragment { 88 struct pf_fragment_cmp fr_key; 89 #define fr_src fr_key.frc_src 90 #define fr_dst fr_key.frc_dst 91 #define fr_id fr_key.frc_id 92 #define fr_af fr_key.frc_af 93 #define fr_proto fr_key.frc_proto 94 95 /* pointers to queue element */ 96 struct pf_frent *fr_firstoff[PF_FRAG_ENTRY_POINTS]; 97 /* count entries between pointers */ 98 uint8_t fr_entries[PF_FRAG_ENTRY_POINTS]; 99 RB_ENTRY(pf_fragment) fr_entry; 100 TAILQ_ENTRY(pf_fragment) frag_next; 101 uint32_t fr_timeout; 102 TAILQ_HEAD(pf_fragq, pf_frent) fr_queue; 103 uint16_t fr_maxlen; /* maximum length of single fragment */ 104 u_int16_t fr_holes; /* number of holes in the queue */ 105 }; 106 107 VNET_DEFINE_STATIC(struct mtx, pf_frag_mtx); 108 #define V_pf_frag_mtx VNET(pf_frag_mtx) 109 #define PF_FRAG_LOCK() mtx_lock(&V_pf_frag_mtx) 110 #define PF_FRAG_UNLOCK() mtx_unlock(&V_pf_frag_mtx) 111 #define PF_FRAG_ASSERT() mtx_assert(&V_pf_frag_mtx, MA_OWNED) 112 113 VNET_DEFINE(uma_zone_t, pf_state_scrub_z); /* XXX: shared with pfsync */ 114 115 VNET_DEFINE_STATIC(uma_zone_t, pf_frent_z); 116 #define V_pf_frent_z VNET(pf_frent_z) 117 VNET_DEFINE_STATIC(uma_zone_t, pf_frag_z); 118 #define V_pf_frag_z VNET(pf_frag_z) 119 120 TAILQ_HEAD(pf_fragqueue, pf_fragment); 121 TAILQ_HEAD(pf_cachequeue, pf_fragment); 122 VNET_DEFINE_STATIC(struct pf_fragqueue, pf_fragqueue); 123 #define V_pf_fragqueue VNET(pf_fragqueue) 124 RB_HEAD(pf_frag_tree, pf_fragment); 125 VNET_DEFINE_STATIC(struct pf_frag_tree, pf_frag_tree); 126 #define V_pf_frag_tree VNET(pf_frag_tree) 127 static int pf_frag_compare(struct pf_fragment *, 128 struct pf_fragment *); 129 static RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 130 static RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 131 132 static void pf_flush_fragments(void); 133 static void pf_free_fragment(struct pf_fragment *); 134 135 static struct pf_frent *pf_create_fragment(u_short *); 136 static int pf_frent_holes(struct pf_frent *frent); 137 static struct pf_fragment *pf_find_fragment(struct pf_fragment_cmp *key, 138 struct pf_frag_tree *tree); 139 static inline int pf_frent_index(struct pf_frent *); 140 static int pf_frent_insert(struct pf_fragment *, 141 struct pf_frent *, struct pf_frent *); 142 void pf_frent_remove(struct pf_fragment *, 143 struct pf_frent *); 144 struct pf_frent *pf_frent_previous(struct pf_fragment *, 145 struct pf_frent *); 146 static struct pf_fragment *pf_fillup_fragment(struct pf_fragment_cmp *, 147 struct pf_frent *, u_short *); 148 static struct mbuf *pf_join_fragment(struct pf_fragment *); 149 #ifdef INET 150 static int pf_reassemble(struct mbuf **, int, u_short *); 151 #endif /* INET */ 152 #ifdef INET6 153 static int pf_reassemble6(struct mbuf **, 154 struct ip6_frag *, uint16_t, uint16_t, u_short *); 155 #endif /* INET6 */ 156 157 #define DPFPRINTF(x) do { \ 158 if (V_pf_status.debug >= PF_DEBUG_MISC) { \ 159 printf("%s: ", __func__); \ 160 printf x ; \ 161 } \ 162 } while(0) 163 164 #ifdef INET 165 static void 166 pf_ip2key(struct ip *ip, int dir, struct pf_fragment_cmp *key) 167 { 168 169 key->frc_src.v4 = ip->ip_src; 170 key->frc_dst.v4 = ip->ip_dst; 171 key->frc_af = AF_INET; 172 key->frc_proto = ip->ip_p; 173 key->frc_id = ip->ip_id; 174 } 175 #endif /* INET */ 176 177 void 178 pf_normalize_init(void) 179 { 180 181 V_pf_frag_z = uma_zcreate("pf frags", sizeof(struct pf_fragment), 182 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 183 V_pf_frent_z = uma_zcreate("pf frag entries", sizeof(struct pf_frent), 184 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 185 V_pf_state_scrub_z = uma_zcreate("pf state scrubs", 186 sizeof(struct pf_state_scrub), NULL, NULL, NULL, NULL, 187 UMA_ALIGN_PTR, 0); 188 189 mtx_init(&V_pf_frag_mtx, "pf fragments", NULL, MTX_DEF); 190 191 V_pf_limits[PF_LIMIT_FRAGS].zone = V_pf_frent_z; 192 V_pf_limits[PF_LIMIT_FRAGS].limit = PFFRAG_FRENT_HIWAT; 193 uma_zone_set_max(V_pf_frent_z, PFFRAG_FRENT_HIWAT); 194 uma_zone_set_warning(V_pf_frent_z, "PF frag entries limit reached"); 195 196 TAILQ_INIT(&V_pf_fragqueue); 197 } 198 199 void 200 pf_normalize_cleanup(void) 201 { 202 203 uma_zdestroy(V_pf_state_scrub_z); 204 uma_zdestroy(V_pf_frent_z); 205 uma_zdestroy(V_pf_frag_z); 206 207 mtx_destroy(&V_pf_frag_mtx); 208 } 209 210 static int 211 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b) 212 { 213 int diff; 214 215 if ((diff = a->fr_id - b->fr_id) != 0) 216 return (diff); 217 if ((diff = a->fr_proto - b->fr_proto) != 0) 218 return (diff); 219 if ((diff = a->fr_af - b->fr_af) != 0) 220 return (diff); 221 if ((diff = pf_addr_cmp(&a->fr_src, &b->fr_src, a->fr_af)) != 0) 222 return (diff); 223 if ((diff = pf_addr_cmp(&a->fr_dst, &b->fr_dst, a->fr_af)) != 0) 224 return (diff); 225 return (0); 226 } 227 228 void 229 pf_purge_expired_fragments(void) 230 { 231 u_int32_t expire = time_uptime - 232 V_pf_default_rule.timeout[PFTM_FRAG]; 233 234 pf_purge_fragments(expire); 235 } 236 237 void 238 pf_purge_fragments(uint32_t expire) 239 { 240 struct pf_fragment *frag; 241 242 PF_FRAG_LOCK(); 243 while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) { 244 if (frag->fr_timeout > expire) 245 break; 246 247 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); 248 pf_free_fragment(frag); 249 } 250 251 PF_FRAG_UNLOCK(); 252 } 253 254 /* 255 * Try to flush old fragments to make space for new ones 256 */ 257 static void 258 pf_flush_fragments(void) 259 { 260 struct pf_fragment *frag; 261 int goal; 262 263 PF_FRAG_ASSERT(); 264 265 goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10; 266 DPFPRINTF(("trying to free %d frag entriess\n", goal)); 267 while (goal < uma_zone_get_cur(V_pf_frent_z)) { 268 frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue); 269 if (frag) 270 pf_free_fragment(frag); 271 else 272 break; 273 } 274 } 275 276 /* 277 * Remove a fragment from the fragment queue, free its fragment entries, 278 * and free the fragment itself. 279 */ 280 static void 281 pf_free_fragment(struct pf_fragment *frag) 282 { 283 struct pf_frent *frent; 284 285 PF_FRAG_ASSERT(); 286 287 RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag); 288 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next); 289 290 /* Free all fragment entries */ 291 while ((frent = TAILQ_FIRST(&frag->fr_queue)) != NULL) { 292 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 293 294 m_freem(frent->fe_m); 295 uma_zfree(V_pf_frent_z, frent); 296 } 297 298 uma_zfree(V_pf_frag_z, frag); 299 } 300 301 static struct pf_fragment * 302 pf_find_fragment(struct pf_fragment_cmp *key, struct pf_frag_tree *tree) 303 { 304 struct pf_fragment *frag; 305 306 PF_FRAG_ASSERT(); 307 308 frag = RB_FIND(pf_frag_tree, tree, (struct pf_fragment *)key); 309 if (frag != NULL) { 310 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next); 311 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next); 312 } 313 314 return (frag); 315 } 316 317 static struct pf_frent * 318 pf_create_fragment(u_short *reason) 319 { 320 struct pf_frent *frent; 321 322 PF_FRAG_ASSERT(); 323 324 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT); 325 if (frent == NULL) { 326 pf_flush_fragments(); 327 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT); 328 if (frent == NULL) { 329 REASON_SET(reason, PFRES_MEMORY); 330 return (NULL); 331 } 332 } 333 334 return (frent); 335 } 336 337 /* 338 * Calculate the additional holes that were created in the fragment 339 * queue by inserting this fragment. A fragment in the middle 340 * creates one more hole by splitting. For each connected side, 341 * it loses one hole. 342 * Fragment entry must be in the queue when calling this function. 343 */ 344 static int 345 pf_frent_holes(struct pf_frent *frent) 346 { 347 struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next); 348 struct pf_frent *next = TAILQ_NEXT(frent, fr_next); 349 int holes = 1; 350 351 if (prev == NULL) { 352 if (frent->fe_off == 0) 353 holes--; 354 } else { 355 KASSERT(frent->fe_off != 0, ("frent->fe_off != 0")); 356 if (frent->fe_off == prev->fe_off + prev->fe_len) 357 holes--; 358 } 359 if (next == NULL) { 360 if (!frent->fe_mff) 361 holes--; 362 } else { 363 KASSERT(frent->fe_mff, ("frent->fe_mff")); 364 if (next->fe_off == frent->fe_off + frent->fe_len) 365 holes--; 366 } 367 return holes; 368 } 369 370 static inline int 371 pf_frent_index(struct pf_frent *frent) 372 { 373 /* 374 * We have an array of 16 entry points to the queue. A full size 375 * 65535 octet IP packet can have 8192 fragments. So the queue 376 * traversal length is at most 512 and at most 16 entry points are 377 * checked. We need 128 additional bytes on a 64 bit architecture. 378 */ 379 CTASSERT(((u_int16_t)0xffff &~ 7) / (0x10000 / PF_FRAG_ENTRY_POINTS) == 380 16 - 1); 381 CTASSERT(((u_int16_t)0xffff >> 3) / PF_FRAG_ENTRY_POINTS == 512 - 1); 382 383 return frent->fe_off / (0x10000 / PF_FRAG_ENTRY_POINTS); 384 } 385 386 static int 387 pf_frent_insert(struct pf_fragment *frag, struct pf_frent *frent, 388 struct pf_frent *prev) 389 { 390 int index; 391 392 CTASSERT(PF_FRAG_ENTRY_LIMIT <= 0xff); 393 394 /* 395 * A packet has at most 65536 octets. With 16 entry points, each one 396 * spawns 4096 octets. We limit these to 64 fragments each, which 397 * means on average every fragment must have at least 64 octets. 398 */ 399 index = pf_frent_index(frent); 400 if (frag->fr_entries[index] >= PF_FRAG_ENTRY_LIMIT) 401 return ENOBUFS; 402 frag->fr_entries[index]++; 403 404 if (prev == NULL) { 405 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next); 406 } else { 407 KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off, 408 ("overlapping fragment")); 409 TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next); 410 } 411 412 if (frag->fr_firstoff[index] == NULL) { 413 KASSERT(prev == NULL || pf_frent_index(prev) < index, 414 ("prev == NULL || pf_frent_index(pref) < index")); 415 frag->fr_firstoff[index] = frent; 416 } else { 417 if (frent->fe_off < frag->fr_firstoff[index]->fe_off) { 418 KASSERT(prev == NULL || pf_frent_index(prev) < index, 419 ("prev == NULL || pf_frent_index(pref) < index")); 420 frag->fr_firstoff[index] = frent; 421 } else { 422 KASSERT(prev != NULL, ("prev != NULL")); 423 KASSERT(pf_frent_index(prev) == index, 424 ("pf_frent_index(prev) == index")); 425 } 426 } 427 428 frag->fr_holes += pf_frent_holes(frent); 429 430 return 0; 431 } 432 433 void 434 pf_frent_remove(struct pf_fragment *frag, struct pf_frent *frent) 435 { 436 #ifdef INVARIANTS 437 struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next); 438 #endif /* INVARIANTS */ 439 struct pf_frent *next = TAILQ_NEXT(frent, fr_next); 440 int index; 441 442 frag->fr_holes -= pf_frent_holes(frent); 443 444 index = pf_frent_index(frent); 445 KASSERT(frag->fr_firstoff[index] != NULL, ("frent not found")); 446 if (frag->fr_firstoff[index]->fe_off == frent->fe_off) { 447 if (next == NULL) { 448 frag->fr_firstoff[index] = NULL; 449 } else { 450 KASSERT(frent->fe_off + frent->fe_len <= next->fe_off, 451 ("overlapping fragment")); 452 if (pf_frent_index(next) == index) { 453 frag->fr_firstoff[index] = next; 454 } else { 455 frag->fr_firstoff[index] = NULL; 456 } 457 } 458 } else { 459 KASSERT(frag->fr_firstoff[index]->fe_off < frent->fe_off, 460 ("frag->fr_firstoff[index]->fe_off < frent->fe_off")); 461 KASSERT(prev != NULL, ("prev != NULL")); 462 KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off, 463 ("overlapping fragment")); 464 KASSERT(pf_frent_index(prev) == index, 465 ("pf_frent_index(prev) == index")); 466 } 467 468 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 469 470 KASSERT(frag->fr_entries[index] > 0, ("No fragments remaining")); 471 frag->fr_entries[index]--; 472 } 473 474 struct pf_frent * 475 pf_frent_previous(struct pf_fragment *frag, struct pf_frent *frent) 476 { 477 struct pf_frent *prev, *next; 478 int index; 479 480 /* 481 * If there are no fragments after frag, take the final one. Assume 482 * that the global queue is not empty. 483 */ 484 prev = TAILQ_LAST(&frag->fr_queue, pf_fragq); 485 KASSERT(prev != NULL, ("prev != NULL")); 486 if (prev->fe_off <= frent->fe_off) 487 return prev; 488 /* 489 * We want to find a fragment entry that is before frag, but still 490 * close to it. Find the first fragment entry that is in the same 491 * entry point or in the first entry point after that. As we have 492 * already checked that there are entries behind frag, this will 493 * succeed. 494 */ 495 for (index = pf_frent_index(frent); index < PF_FRAG_ENTRY_POINTS; 496 index++) { 497 prev = frag->fr_firstoff[index]; 498 if (prev != NULL) 499 break; 500 } 501 KASSERT(prev != NULL, ("prev != NULL")); 502 /* 503 * In prev we may have a fragment from the same entry point that is 504 * before frent, or one that is just one position behind frent. 505 * In the latter case, we go back one step and have the predecessor. 506 * There may be none if the new fragment will be the first one. 507 */ 508 if (prev->fe_off > frent->fe_off) { 509 prev = TAILQ_PREV(prev, pf_fragq, fr_next); 510 if (prev == NULL) 511 return NULL; 512 KASSERT(prev->fe_off <= frent->fe_off, 513 ("prev->fe_off <= frent->fe_off")); 514 return prev; 515 } 516 /* 517 * In prev is the first fragment of the entry point. The offset 518 * of frag is behind it. Find the closest previous fragment. 519 */ 520 for (next = TAILQ_NEXT(prev, fr_next); next != NULL; 521 next = TAILQ_NEXT(next, fr_next)) { 522 if (next->fe_off > frent->fe_off) 523 break; 524 prev = next; 525 } 526 return prev; 527 } 528 529 static struct pf_fragment * 530 pf_fillup_fragment(struct pf_fragment_cmp *key, struct pf_frent *frent, 531 u_short *reason) 532 { 533 struct pf_frent *after, *next, *prev; 534 struct pf_fragment *frag; 535 uint16_t total; 536 537 PF_FRAG_ASSERT(); 538 539 /* No empty fragments. */ 540 if (frent->fe_len == 0) { 541 DPFPRINTF(("bad fragment: len 0\n")); 542 goto bad_fragment; 543 } 544 545 /* All fragments are 8 byte aligned. */ 546 if (frent->fe_mff && (frent->fe_len & 0x7)) { 547 DPFPRINTF(("bad fragment: mff and len %d\n", frent->fe_len)); 548 goto bad_fragment; 549 } 550 551 /* Respect maximum length, IP_MAXPACKET == IPV6_MAXPACKET. */ 552 if (frent->fe_off + frent->fe_len > IP_MAXPACKET) { 553 DPFPRINTF(("bad fragment: max packet %d\n", 554 frent->fe_off + frent->fe_len)); 555 goto bad_fragment; 556 } 557 558 DPFPRINTF((key->frc_af == AF_INET ? 559 "reass frag %d @ %d-%d\n" : "reass frag %#08x @ %d-%d\n", 560 key->frc_id, frent->fe_off, frent->fe_off + frent->fe_len)); 561 562 /* Fully buffer all of the fragments in this fragment queue. */ 563 frag = pf_find_fragment(key, &V_pf_frag_tree); 564 565 /* Create a new reassembly queue for this packet. */ 566 if (frag == NULL) { 567 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 568 if (frag == NULL) { 569 pf_flush_fragments(); 570 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 571 if (frag == NULL) { 572 REASON_SET(reason, PFRES_MEMORY); 573 goto drop_fragment; 574 } 575 } 576 577 *(struct pf_fragment_cmp *)frag = *key; 578 memset(frag->fr_firstoff, 0, sizeof(frag->fr_firstoff)); 579 memset(frag->fr_entries, 0, sizeof(frag->fr_entries)); 580 frag->fr_timeout = time_uptime; 581 TAILQ_INIT(&frag->fr_queue); 582 frag->fr_maxlen = frent->fe_len; 583 frag->fr_holes = 1; 584 585 RB_INSERT(pf_frag_tree, &V_pf_frag_tree, frag); 586 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next); 587 588 /* We do not have a previous fragment, cannot fail. */ 589 pf_frent_insert(frag, frent, NULL); 590 591 return (frag); 592 } 593 594 KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue")); 595 596 /* Remember maximum fragment len for refragmentation. */ 597 if (frent->fe_len > frag->fr_maxlen) 598 frag->fr_maxlen = frent->fe_len; 599 600 /* Maximum data we have seen already. */ 601 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 602 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 603 604 /* Non terminal fragments must have more fragments flag. */ 605 if (frent->fe_off + frent->fe_len < total && !frent->fe_mff) 606 goto bad_fragment; 607 608 /* Check if we saw the last fragment already. */ 609 if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) { 610 if (frent->fe_off + frent->fe_len > total || 611 (frent->fe_off + frent->fe_len == total && frent->fe_mff)) 612 goto bad_fragment; 613 } else { 614 if (frent->fe_off + frent->fe_len == total && !frent->fe_mff) 615 goto bad_fragment; 616 } 617 618 /* Find neighbors for newly inserted fragment */ 619 prev = pf_frent_previous(frag, frent); 620 if (prev == NULL) { 621 after = TAILQ_FIRST(&frag->fr_queue); 622 KASSERT(after != NULL, ("after != NULL")); 623 } else { 624 after = TAILQ_NEXT(prev, fr_next); 625 } 626 627 if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) { 628 uint16_t precut; 629 630 if (frag->fr_af == AF_INET6) 631 goto free_fragment; 632 633 precut = prev->fe_off + prev->fe_len - frent->fe_off; 634 if (precut >= frent->fe_len) { 635 DPFPRINTF(("new frag overlapped\n")); 636 goto drop_fragment; 637 } 638 DPFPRINTF(("frag head overlap %d\n", precut)); 639 m_adj(frent->fe_m, precut); 640 frent->fe_off += precut; 641 frent->fe_len -= precut; 642 } 643 644 for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off; 645 after = next) { 646 uint16_t aftercut; 647 648 aftercut = frent->fe_off + frent->fe_len - after->fe_off; 649 if (aftercut < after->fe_len) { 650 DPFPRINTF(("frag tail overlap %d", aftercut)); 651 m_adj(after->fe_m, aftercut); 652 /* Fragment may switch queue as fe_off changes */ 653 pf_frent_remove(frag, after); 654 after->fe_off += aftercut; 655 after->fe_len -= aftercut; 656 /* Insert into correct queue */ 657 if (pf_frent_insert(frag, after, prev)) { 658 DPFPRINTF(("fragment requeue limit exceeded")); 659 m_freem(after->fe_m); 660 uma_zfree(V_pf_frent_z, after); 661 /* There is not way to recover */ 662 goto free_fragment; 663 } 664 break; 665 } 666 667 /* This fragment is completely overlapped, lose it. */ 668 DPFPRINTF(("old frag overlapped\n")); 669 next = TAILQ_NEXT(after, fr_next); 670 pf_frent_remove(frag, after); 671 m_freem(after->fe_m); 672 uma_zfree(V_pf_frent_z, after); 673 } 674 675 /* If part of the queue gets too long, there is not way to recover. */ 676 if (pf_frent_insert(frag, frent, prev)) { 677 DPFPRINTF(("fragment queue limit exceeded\n")); 678 goto bad_fragment; 679 } 680 681 return (frag); 682 683 free_fragment: 684 /* 685 * RFC 5722, Errata 3089: When reassembling an IPv6 datagram, if one 686 * or more its constituent fragments is determined to be an overlapping 687 * fragment, the entire datagram (and any constituent fragments) MUST 688 * be silently discarded. 689 */ 690 DPFPRINTF(("flush overlapping fragments\n")); 691 pf_free_fragment(frag); 692 693 bad_fragment: 694 REASON_SET(reason, PFRES_FRAG); 695 drop_fragment: 696 uma_zfree(V_pf_frent_z, frent); 697 return (NULL); 698 } 699 700 static struct mbuf * 701 pf_join_fragment(struct pf_fragment *frag) 702 { 703 struct mbuf *m, *m2; 704 struct pf_frent *frent; 705 706 frent = TAILQ_FIRST(&frag->fr_queue); 707 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 708 709 m = frent->fe_m; 710 if ((frent->fe_hdrlen + frent->fe_len) < m->m_pkthdr.len) 711 m_adj(m, (frent->fe_hdrlen + frent->fe_len) - m->m_pkthdr.len); 712 uma_zfree(V_pf_frent_z, frent); 713 while ((frent = TAILQ_FIRST(&frag->fr_queue)) != NULL) { 714 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 715 716 m2 = frent->fe_m; 717 /* Strip off ip header. */ 718 m_adj(m2, frent->fe_hdrlen); 719 /* Strip off any trailing bytes. */ 720 if (frent->fe_len < m2->m_pkthdr.len) 721 m_adj(m2, frent->fe_len - m2->m_pkthdr.len); 722 723 uma_zfree(V_pf_frent_z, frent); 724 m_cat(m, m2); 725 } 726 727 /* Remove from fragment queue. */ 728 pf_free_fragment(frag); 729 730 return (m); 731 } 732 733 #ifdef INET 734 static int 735 pf_reassemble(struct mbuf **m0, int dir, u_short *reason) 736 { 737 struct mbuf *m = *m0; 738 struct ip *ip = mtod(m, struct ip *); 739 struct pf_frent *frent; 740 struct pf_fragment *frag; 741 struct m_tag *mtag; 742 struct pf_fragment_tag *ftag; 743 struct pf_fragment_cmp key; 744 uint16_t total, hdrlen; 745 uint32_t frag_id; 746 uint16_t maxlen; 747 748 /* Get an entry for the fragment queue */ 749 if ((frent = pf_create_fragment(reason)) == NULL) 750 return (PF_DROP); 751 752 frent->fe_m = m; 753 frent->fe_hdrlen = ip->ip_hl << 2; 754 frent->fe_extoff = 0; 755 frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2); 756 frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3; 757 frent->fe_mff = ntohs(ip->ip_off) & IP_MF; 758 759 pf_ip2key(ip, dir, &key); 760 761 if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) 762 return (PF_DROP); 763 764 /* The mbuf is part of the fragment entry, no direct free or access */ 765 m = *m0 = NULL; 766 767 if (frag->fr_holes) { 768 DPFPRINTF(("frag %d, holes %d\n", frag->fr_id, frag->fr_holes)); 769 return (PF_PASS); /* drop because *m0 is NULL, no error */ 770 } 771 772 /* We have all the data */ 773 frent = TAILQ_FIRST(&frag->fr_queue); 774 KASSERT(frent != NULL, ("frent != NULL")); 775 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 776 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 777 hdrlen = frent->fe_hdrlen; 778 779 maxlen = frag->fr_maxlen; 780 frag_id = frag->fr_id; 781 m = *m0 = pf_join_fragment(frag); 782 frag = NULL; 783 784 if (m->m_flags & M_PKTHDR) { 785 int plen = 0; 786 for (m = *m0; m; m = m->m_next) 787 plen += m->m_len; 788 m = *m0; 789 m->m_pkthdr.len = plen; 790 } 791 792 if ((mtag = m_tag_get(PACKET_TAG_PF_REASSEMBLED, 793 sizeof(struct pf_fragment_tag), M_NOWAIT)) == NULL) { 794 REASON_SET(reason, PFRES_SHORT); 795 /* PF_DROP requires a valid mbuf *m0 in pf_test() */ 796 return (PF_DROP); 797 } 798 ftag = (struct pf_fragment_tag *)(mtag + 1); 799 ftag->ft_hdrlen = hdrlen; 800 ftag->ft_extoff = 0; 801 ftag->ft_maxlen = maxlen; 802 ftag->ft_id = frag_id; 803 m_tag_prepend(m, mtag); 804 805 ip = mtod(m, struct ip *); 806 ip->ip_sum = pf_cksum_fixup(ip->ip_sum, ip->ip_len, 807 htons(hdrlen + total), 0); 808 ip->ip_len = htons(hdrlen + total); 809 ip->ip_sum = pf_cksum_fixup(ip->ip_sum, ip->ip_off, 810 ip->ip_off & ~(IP_MF|IP_OFFMASK), 0); 811 ip->ip_off &= ~(IP_MF|IP_OFFMASK); 812 813 if (hdrlen + total > IP_MAXPACKET) { 814 DPFPRINTF(("drop: too big: %d\n", total)); 815 ip->ip_len = 0; 816 REASON_SET(reason, PFRES_SHORT); 817 /* PF_DROP requires a valid mbuf *m0 in pf_test() */ 818 return (PF_DROP); 819 } 820 821 DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len))); 822 return (PF_PASS); 823 } 824 #endif /* INET */ 825 826 #ifdef INET6 827 static int 828 pf_reassemble6(struct mbuf **m0, struct ip6_frag *fraghdr, 829 uint16_t hdrlen, uint16_t extoff, u_short *reason) 830 { 831 struct mbuf *m = *m0; 832 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 833 struct pf_frent *frent; 834 struct pf_fragment *frag; 835 struct pf_fragment_cmp key; 836 struct m_tag *mtag; 837 struct pf_fragment_tag *ftag; 838 int off; 839 uint32_t frag_id; 840 uint16_t total, maxlen; 841 uint8_t proto; 842 843 PF_FRAG_LOCK(); 844 845 /* Get an entry for the fragment queue. */ 846 if ((frent = pf_create_fragment(reason)) == NULL) { 847 PF_FRAG_UNLOCK(); 848 return (PF_DROP); 849 } 850 851 frent->fe_m = m; 852 frent->fe_hdrlen = hdrlen; 853 frent->fe_extoff = extoff; 854 frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen; 855 frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK); 856 frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG; 857 858 key.frc_src.v6 = ip6->ip6_src; 859 key.frc_dst.v6 = ip6->ip6_dst; 860 key.frc_af = AF_INET6; 861 /* Only the first fragment's protocol is relevant. */ 862 key.frc_proto = 0; 863 key.frc_id = fraghdr->ip6f_ident; 864 865 if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) { 866 PF_FRAG_UNLOCK(); 867 return (PF_DROP); 868 } 869 870 /* The mbuf is part of the fragment entry, no direct free or access. */ 871 m = *m0 = NULL; 872 873 if (frag->fr_holes) { 874 DPFPRINTF(("frag %d, holes %d\n", frag->fr_id, 875 frag->fr_holes)); 876 PF_FRAG_UNLOCK(); 877 return (PF_PASS); /* Drop because *m0 is NULL, no error. */ 878 } 879 880 /* We have all the data. */ 881 frent = TAILQ_FIRST(&frag->fr_queue); 882 KASSERT(frent != NULL, ("frent != NULL")); 883 extoff = frent->fe_extoff; 884 maxlen = frag->fr_maxlen; 885 frag_id = frag->fr_id; 886 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 887 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 888 hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag); 889 890 m = *m0 = pf_join_fragment(frag); 891 frag = NULL; 892 893 PF_FRAG_UNLOCK(); 894 895 /* Take protocol from first fragment header. */ 896 m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off); 897 KASSERT(m, ("%s: short mbuf chain", __func__)); 898 proto = *(mtod(m, uint8_t *) + off); 899 m = *m0; 900 901 /* Delete frag6 header */ 902 if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0) 903 goto fail; 904 905 if (m->m_flags & M_PKTHDR) { 906 int plen = 0; 907 for (m = *m0; m; m = m->m_next) 908 plen += m->m_len; 909 m = *m0; 910 m->m_pkthdr.len = plen; 911 } 912 913 if ((mtag = m_tag_get(PACKET_TAG_PF_REASSEMBLED, 914 sizeof(struct pf_fragment_tag), M_NOWAIT)) == NULL) 915 goto fail; 916 ftag = (struct pf_fragment_tag *)(mtag + 1); 917 ftag->ft_hdrlen = hdrlen; 918 ftag->ft_extoff = extoff; 919 ftag->ft_maxlen = maxlen; 920 ftag->ft_id = frag_id; 921 m_tag_prepend(m, mtag); 922 923 ip6 = mtod(m, struct ip6_hdr *); 924 ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total); 925 if (extoff) { 926 /* Write protocol into next field of last extension header. */ 927 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt), 928 &off); 929 KASSERT(m, ("%s: short mbuf chain", __func__)); 930 *(mtod(m, char *) + off) = proto; 931 m = *m0; 932 } else 933 ip6->ip6_nxt = proto; 934 935 if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) { 936 DPFPRINTF(("drop: too big: %d\n", total)); 937 ip6->ip6_plen = 0; 938 REASON_SET(reason, PFRES_SHORT); 939 /* PF_DROP requires a valid mbuf *m0 in pf_test6(). */ 940 return (PF_DROP); 941 } 942 943 DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip6->ip6_plen))); 944 return (PF_PASS); 945 946 fail: 947 REASON_SET(reason, PFRES_MEMORY); 948 /* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */ 949 return (PF_DROP); 950 } 951 #endif /* INET6 */ 952 953 #ifdef INET6 954 int 955 pf_max_frag_size(struct mbuf *m) 956 { 957 struct m_tag *tag; 958 struct pf_fragment_tag *ftag; 959 960 tag = m_tag_find(m, PACKET_TAG_PF_REASSEMBLED, NULL); 961 if (tag == NULL) 962 return (m->m_pkthdr.len); 963 964 ftag = (struct pf_fragment_tag *)(tag + 1); 965 966 return (ftag->ft_maxlen); 967 } 968 969 int 970 pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag, 971 struct ifnet *rt, bool forward) 972 { 973 struct mbuf *m = *m0, *t; 974 struct ip6_hdr *hdr; 975 struct pf_fragment_tag *ftag = (struct pf_fragment_tag *)(mtag + 1); 976 struct pf_pdesc pd; 977 uint32_t frag_id; 978 uint16_t hdrlen, extoff, maxlen; 979 uint8_t proto; 980 int error, action; 981 982 hdrlen = ftag->ft_hdrlen; 983 extoff = ftag->ft_extoff; 984 maxlen = ftag->ft_maxlen; 985 frag_id = ftag->ft_id; 986 m_tag_delete(m, mtag); 987 mtag = NULL; 988 ftag = NULL; 989 990 if (extoff) { 991 int off; 992 993 /* Use protocol from next field of last extension header */ 994 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt), 995 &off); 996 KASSERT((m != NULL), ("pf_refragment6: short mbuf chain")); 997 proto = *(mtod(m, uint8_t *) + off); 998 *(mtod(m, char *) + off) = IPPROTO_FRAGMENT; 999 m = *m0; 1000 } else { 1001 hdr = mtod(m, struct ip6_hdr *); 1002 proto = hdr->ip6_nxt; 1003 hdr->ip6_nxt = IPPROTO_FRAGMENT; 1004 } 1005 1006 /* In case of link-local traffic we'll need a scope set. */ 1007 hdr = mtod(m, struct ip6_hdr *); 1008 1009 in6_setscope(&hdr->ip6_src, ifp, NULL); 1010 in6_setscope(&hdr->ip6_dst, ifp, NULL); 1011 1012 /* The MTU must be a multiple of 8 bytes, or we risk doing the 1013 * fragmentation wrong. */ 1014 maxlen = maxlen & ~7; 1015 1016 /* 1017 * Maxlen may be less than 8 if there was only a single 1018 * fragment. As it was fragmented before, add a fragment 1019 * header also for a single fragment. If total or maxlen 1020 * is less than 8, ip6_fragment() will return EMSGSIZE and 1021 * we drop the packet. 1022 */ 1023 error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id); 1024 m = (*m0)->m_nextpkt; 1025 (*m0)->m_nextpkt = NULL; 1026 if (error == 0) { 1027 /* The first mbuf contains the unfragmented packet. */ 1028 m_freem(*m0); 1029 *m0 = NULL; 1030 action = PF_PASS; 1031 } else { 1032 /* Drop expects an mbuf to free. */ 1033 DPFPRINTF(("refragment error %d\n", error)); 1034 action = PF_DROP; 1035 } 1036 for (; m; m = t) { 1037 t = m->m_nextpkt; 1038 m->m_nextpkt = NULL; 1039 m->m_flags |= M_SKIP_FIREWALL; 1040 memset(&pd, 0, sizeof(pd)); 1041 pd.pf_mtag = pf_find_mtag(m); 1042 if (error != 0) { 1043 m_freem(m); 1044 continue; 1045 } 1046 if (rt != NULL) { 1047 struct sockaddr_in6 dst; 1048 hdr = mtod(m, struct ip6_hdr *); 1049 1050 bzero(&dst, sizeof(dst)); 1051 dst.sin6_family = AF_INET6; 1052 dst.sin6_len = sizeof(dst); 1053 dst.sin6_addr = hdr->ip6_dst; 1054 1055 if (m->m_pkthdr.len <= if_getmtu(ifp)) { 1056 nd6_output_ifp(rt, rt, m, &dst, NULL); 1057 } else { 1058 in6_ifstat_inc(ifp, ifs6_in_toobig); 1059 icmp6_error(m, ICMP6_PACKET_TOO_BIG, 0, 1060 if_getmtu(ifp)); 1061 } 1062 } else if (forward) { 1063 MPASS(m->m_pkthdr.rcvif != NULL); 1064 ip6_forward(m, 0); 1065 } else { 1066 (void)ip6_output(m, NULL, NULL, 0, NULL, NULL, 1067 NULL); 1068 } 1069 } 1070 1071 return (action); 1072 } 1073 #endif /* INET6 */ 1074 1075 #ifdef INET 1076 int 1077 pf_normalize_ip(u_short *reason, struct pf_pdesc *pd) 1078 { 1079 struct pf_krule *r; 1080 struct ip *h = mtod(pd->m, struct ip *); 1081 int mff = (ntohs(h->ip_off) & IP_MF); 1082 int hlen = h->ip_hl << 2; 1083 u_int16_t fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3; 1084 u_int16_t max; 1085 int ip_len; 1086 int tag = -1; 1087 int verdict; 1088 bool scrub_compat; 1089 1090 PF_RULES_RASSERT(); 1091 1092 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1093 /* 1094 * Check if there are any scrub rules, matching or not. 1095 * Lack of scrub rules means: 1096 * - enforced packet normalization operation just like in OpenBSD 1097 * - fragment reassembly depends on V_pf_status.reass 1098 * With scrub rules: 1099 * - packet normalization is performed if there is a matching scrub rule 1100 * - fragment reassembly is performed if the matching rule has no 1101 * PFRULE_FRAGMENT_NOREASS flag 1102 */ 1103 scrub_compat = (r != NULL); 1104 while (r != NULL) { 1105 pf_counter_u64_add(&r->evaluations, 1); 1106 if (pfi_kkif_match(r->kif, pd->kif) == r->ifnot) 1107 r = r->skip[PF_SKIP_IFP]; 1108 else if (r->direction && r->direction != pd->dir) 1109 r = r->skip[PF_SKIP_DIR]; 1110 else if (r->af && r->af != AF_INET) 1111 r = r->skip[PF_SKIP_AF]; 1112 else if (r->proto && r->proto != h->ip_p) 1113 r = r->skip[PF_SKIP_PROTO]; 1114 else if (PF_MISMATCHAW(&r->src.addr, 1115 (struct pf_addr *)&h->ip_src.s_addr, AF_INET, 1116 r->src.neg, pd->kif, M_GETFIB(pd->m))) 1117 r = r->skip[PF_SKIP_SRC_ADDR]; 1118 else if (PF_MISMATCHAW(&r->dst.addr, 1119 (struct pf_addr *)&h->ip_dst.s_addr, AF_INET, 1120 r->dst.neg, NULL, M_GETFIB(pd->m))) 1121 r = r->skip[PF_SKIP_DST_ADDR]; 1122 else if (r->match_tag && !pf_match_tag(pd->m, r, &tag, 1123 pd->pf_mtag ? pd->pf_mtag->tag : 0)) 1124 r = TAILQ_NEXT(r, entries); 1125 else 1126 break; 1127 } 1128 1129 if (scrub_compat) { 1130 /* With scrub rules present IPv4 normalization happens only 1131 * if one of rules has matched and it's not a "no scrub" rule */ 1132 if (r == NULL || r->action == PF_NOSCRUB) 1133 return (PF_PASS); 1134 1135 pf_counter_u64_critical_enter(); 1136 pf_counter_u64_add_protected(&r->packets[pd->dir == PF_OUT], 1); 1137 pf_counter_u64_add_protected(&r->bytes[pd->dir == PF_OUT], pd->tot_len); 1138 pf_counter_u64_critical_exit(); 1139 pf_rule_to_actions(r, &pd->act); 1140 } 1141 1142 /* Check for illegal packets */ 1143 if (hlen < (int)sizeof(struct ip)) { 1144 REASON_SET(reason, PFRES_NORM); 1145 goto drop; 1146 } 1147 1148 if (hlen > ntohs(h->ip_len)) { 1149 REASON_SET(reason, PFRES_NORM); 1150 goto drop; 1151 } 1152 1153 /* Clear IP_DF if the rule uses the no-df option or we're in no-df mode */ 1154 if (((!scrub_compat && V_pf_status.reass & PF_REASS_NODF) || 1155 (r != NULL && r->rule_flag & PFRULE_NODF)) && 1156 (h->ip_off & htons(IP_DF)) 1157 ) { 1158 u_int16_t ip_off = h->ip_off; 1159 1160 h->ip_off &= htons(~IP_DF); 1161 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1162 } 1163 1164 /* We will need other tests here */ 1165 if (!fragoff && !mff) 1166 goto no_fragment; 1167 1168 /* We're dealing with a fragment now. Don't allow fragments 1169 * with IP_DF to enter the cache. If the flag was cleared by 1170 * no-df above, fine. Otherwise drop it. 1171 */ 1172 if (h->ip_off & htons(IP_DF)) { 1173 DPFPRINTF(("IP_DF\n")); 1174 goto bad; 1175 } 1176 1177 ip_len = ntohs(h->ip_len) - hlen; 1178 1179 /* All fragments are 8 byte aligned */ 1180 if (mff && (ip_len & 0x7)) { 1181 DPFPRINTF(("mff and %d\n", ip_len)); 1182 goto bad; 1183 } 1184 1185 /* Respect maximum length */ 1186 if (fragoff + ip_len > IP_MAXPACKET) { 1187 DPFPRINTF(("max packet %d\n", fragoff + ip_len)); 1188 goto bad; 1189 } 1190 1191 if ((!scrub_compat && V_pf_status.reass) || 1192 (r != NULL && !(r->rule_flag & PFRULE_FRAGMENT_NOREASS)) 1193 ) { 1194 max = fragoff + ip_len; 1195 1196 /* Fully buffer all of the fragments 1197 * Might return a completely reassembled mbuf, or NULL */ 1198 PF_FRAG_LOCK(); 1199 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max)); 1200 verdict = pf_reassemble(&pd->m, pd->dir, reason); 1201 PF_FRAG_UNLOCK(); 1202 1203 if (verdict != PF_PASS) 1204 return (PF_DROP); 1205 1206 if (pd->m == NULL) 1207 return (PF_DROP); 1208 1209 h = mtod(pd->m, struct ip *); 1210 pd->tot_len = htons(h->ip_len); 1211 1212 no_fragment: 1213 /* At this point, only IP_DF is allowed in ip_off */ 1214 if (h->ip_off & ~htons(IP_DF)) { 1215 u_int16_t ip_off = h->ip_off; 1216 1217 h->ip_off &= htons(IP_DF); 1218 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1219 } 1220 } 1221 1222 return (PF_PASS); 1223 1224 bad: 1225 DPFPRINTF(("dropping bad fragment\n")); 1226 REASON_SET(reason, PFRES_FRAG); 1227 drop: 1228 if (r != NULL && r->log) 1229 PFLOG_PACKET(PF_DROP, *reason, r, NULL, NULL, pd, 1, NULL); 1230 1231 return (PF_DROP); 1232 } 1233 #endif 1234 1235 #ifdef INET6 1236 int 1237 pf_normalize_ip6(int off, u_short *reason, 1238 struct pf_pdesc *pd) 1239 { 1240 struct pf_krule *r; 1241 struct ip6_hdr *h; 1242 struct ip6_frag frag; 1243 bool scrub_compat; 1244 1245 PF_RULES_RASSERT(); 1246 1247 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1248 /* 1249 * Check if there are any scrub rules, matching or not. 1250 * Lack of scrub rules means: 1251 * - enforced packet normalization operation just like in OpenBSD 1252 * With scrub rules: 1253 * - packet normalization is performed if there is a matching scrub rule 1254 * XXX: Fragment reassembly always performed for IPv6! 1255 */ 1256 scrub_compat = (r != NULL); 1257 while (r != NULL) { 1258 pf_counter_u64_add(&r->evaluations, 1); 1259 if (pfi_kkif_match(r->kif, pd->kif) == r->ifnot) 1260 r = r->skip[PF_SKIP_IFP]; 1261 else if (r->direction && r->direction != pd->dir) 1262 r = r->skip[PF_SKIP_DIR]; 1263 else if (r->af && r->af != AF_INET6) 1264 r = r->skip[PF_SKIP_AF]; 1265 else if (r->proto && r->proto != pd->proto) 1266 r = r->skip[PF_SKIP_PROTO]; 1267 else if (PF_MISMATCHAW(&r->src.addr, 1268 (struct pf_addr *)&pd->src, AF_INET6, 1269 r->src.neg, pd->kif, M_GETFIB(pd->m))) 1270 r = r->skip[PF_SKIP_SRC_ADDR]; 1271 else if (PF_MISMATCHAW(&r->dst.addr, 1272 (struct pf_addr *)&pd->dst, AF_INET6, 1273 r->dst.neg, NULL, M_GETFIB(pd->m))) 1274 r = r->skip[PF_SKIP_DST_ADDR]; 1275 else 1276 break; 1277 } 1278 1279 if (scrub_compat) { 1280 /* With scrub rules present IPv6 normalization happens only 1281 * if one of rules has matched and it's not a "no scrub" rule */ 1282 if (r == NULL || r->action == PF_NOSCRUB) 1283 return (PF_PASS); 1284 1285 pf_counter_u64_critical_enter(); 1286 pf_counter_u64_add_protected(&r->packets[pd->dir == PF_OUT], 1); 1287 pf_counter_u64_add_protected(&r->bytes[pd->dir == PF_OUT], pd->tot_len); 1288 pf_counter_u64_critical_exit(); 1289 pf_rule_to_actions(r, &pd->act); 1290 } 1291 1292 if (!pf_pull_hdr(pd->m, off, &frag, sizeof(frag), NULL, reason, AF_INET6)) 1293 return (PF_DROP); 1294 1295 /* Offset now points to data portion. */ 1296 off += sizeof(frag); 1297 1298 if (pd->virtual_proto == PF_VPROTO_FRAGMENT) { 1299 /* Returns PF_DROP or *m0 is NULL or completely reassembled 1300 * mbuf. */ 1301 if (pf_reassemble6(&pd->m, &frag, off, pd->extoff, reason) != PF_PASS) 1302 return (PF_DROP); 1303 if (pd->m == NULL) 1304 return (PF_DROP); 1305 h = mtod(pd->m, struct ip6_hdr *); 1306 pd->tot_len = ntohs(h->ip6_plen) + sizeof(struct ip6_hdr); 1307 } 1308 1309 return (PF_PASS); 1310 } 1311 #endif /* INET6 */ 1312 1313 int 1314 pf_normalize_tcp(struct pf_pdesc *pd) 1315 { 1316 struct pf_krule *r, *rm = NULL; 1317 struct tcphdr *th = &pd->hdr.tcp; 1318 int rewrite = 0; 1319 u_short reason; 1320 u_int16_t flags; 1321 sa_family_t af = pd->af; 1322 int srs; 1323 1324 PF_RULES_RASSERT(); 1325 1326 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1327 /* Check if there any scrub rules. Lack of scrub rules means enforced 1328 * packet normalization operation just like in OpenBSD. */ 1329 srs = (r != NULL); 1330 while (r != NULL) { 1331 pf_counter_u64_add(&r->evaluations, 1); 1332 if (pfi_kkif_match(r->kif, pd->kif) == r->ifnot) 1333 r = r->skip[PF_SKIP_IFP]; 1334 else if (r->direction && r->direction != pd->dir) 1335 r = r->skip[PF_SKIP_DIR]; 1336 else if (r->af && r->af != af) 1337 r = r->skip[PF_SKIP_AF]; 1338 else if (r->proto && r->proto != pd->proto) 1339 r = r->skip[PF_SKIP_PROTO]; 1340 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, 1341 r->src.neg, pd->kif, M_GETFIB(pd->m))) 1342 r = r->skip[PF_SKIP_SRC_ADDR]; 1343 else if (r->src.port_op && !pf_match_port(r->src.port_op, 1344 r->src.port[0], r->src.port[1], th->th_sport)) 1345 r = r->skip[PF_SKIP_SRC_PORT]; 1346 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, 1347 r->dst.neg, NULL, M_GETFIB(pd->m))) 1348 r = r->skip[PF_SKIP_DST_ADDR]; 1349 else if (r->dst.port_op && !pf_match_port(r->dst.port_op, 1350 r->dst.port[0], r->dst.port[1], th->th_dport)) 1351 r = r->skip[PF_SKIP_DST_PORT]; 1352 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match( 1353 pf_osfp_fingerprint(pd, th), 1354 r->os_fingerprint)) 1355 r = TAILQ_NEXT(r, entries); 1356 else { 1357 rm = r; 1358 break; 1359 } 1360 } 1361 1362 if (srs) { 1363 /* With scrub rules present TCP normalization happens only 1364 * if one of rules has matched and it's not a "no scrub" rule */ 1365 if (rm == NULL || rm->action == PF_NOSCRUB) 1366 return (PF_PASS); 1367 1368 pf_counter_u64_critical_enter(); 1369 pf_counter_u64_add_protected(&r->packets[pd->dir == PF_OUT], 1); 1370 pf_counter_u64_add_protected(&r->bytes[pd->dir == PF_OUT], pd->tot_len); 1371 pf_counter_u64_critical_exit(); 1372 pf_rule_to_actions(rm, &pd->act); 1373 } 1374 1375 if (rm && rm->rule_flag & PFRULE_REASSEMBLE_TCP) 1376 pd->flags |= PFDESC_TCP_NORM; 1377 1378 flags = tcp_get_flags(th); 1379 if (flags & TH_SYN) { 1380 /* Illegal packet */ 1381 if (flags & TH_RST) 1382 goto tcp_drop; 1383 1384 if (flags & TH_FIN) 1385 goto tcp_drop; 1386 } else { 1387 /* Illegal packet */ 1388 if (!(flags & (TH_ACK|TH_RST))) 1389 goto tcp_drop; 1390 } 1391 1392 if (!(flags & TH_ACK)) { 1393 /* These flags are only valid if ACK is set */ 1394 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG)) 1395 goto tcp_drop; 1396 } 1397 1398 /* Check for illegal header length */ 1399 if (th->th_off < (sizeof(struct tcphdr) >> 2)) 1400 goto tcp_drop; 1401 1402 /* If flags changed, or reserved data set, then adjust */ 1403 if (flags != tcp_get_flags(th) || 1404 (tcp_get_flags(th) & (TH_RES1|TH_RES2|TH_RES2)) != 0) { 1405 u_int16_t ov, nv; 1406 1407 ov = *(u_int16_t *)(&th->th_ack + 1); 1408 flags &= ~(TH_RES1 | TH_RES2 | TH_RES3); 1409 tcp_set_flags(th, flags); 1410 nv = *(u_int16_t *)(&th->th_ack + 1); 1411 1412 th->th_sum = pf_proto_cksum_fixup(pd->m, th->th_sum, ov, nv, 0); 1413 rewrite = 1; 1414 } 1415 1416 /* Remove urgent pointer, if TH_URG is not set */ 1417 if (!(flags & TH_URG) && th->th_urp) { 1418 th->th_sum = pf_proto_cksum_fixup(pd->m, th->th_sum, th->th_urp, 1419 0, 0); 1420 th->th_urp = 0; 1421 rewrite = 1; 1422 } 1423 1424 /* copy back packet headers if we sanitized */ 1425 if (rewrite) 1426 m_copyback(pd->m, pd->off, sizeof(*th), (caddr_t)th); 1427 1428 return (PF_PASS); 1429 1430 tcp_drop: 1431 REASON_SET(&reason, PFRES_NORM); 1432 if (rm != NULL && r->log) 1433 PFLOG_PACKET(PF_DROP, reason, r, NULL, NULL, pd, 1, NULL); 1434 return (PF_DROP); 1435 } 1436 1437 int 1438 pf_normalize_tcp_init(struct pf_pdesc *pd, struct tcphdr *th, 1439 struct pf_state_peer *src) 1440 { 1441 u_int32_t tsval, tsecr; 1442 u_int8_t hdr[60]; 1443 u_int8_t *opt; 1444 1445 KASSERT((src->scrub == NULL), 1446 ("pf_normalize_tcp_init: src->scrub != NULL")); 1447 1448 src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT); 1449 if (src->scrub == NULL) 1450 return (1); 1451 1452 switch (pd->af) { 1453 #ifdef INET 1454 case AF_INET: { 1455 struct ip *h = mtod(pd->m, struct ip *); 1456 src->scrub->pfss_ttl = h->ip_ttl; 1457 break; 1458 } 1459 #endif /* INET */ 1460 #ifdef INET6 1461 case AF_INET6: { 1462 struct ip6_hdr *h = mtod(pd->m, struct ip6_hdr *); 1463 src->scrub->pfss_ttl = h->ip6_hlim; 1464 break; 1465 } 1466 #endif /* INET6 */ 1467 default: 1468 unhandled_af(pd->af); 1469 } 1470 1471 /* 1472 * All normalizations below are only begun if we see the start of 1473 * the connections. They must all set an enabled bit in pfss_flags 1474 */ 1475 if ((tcp_get_flags(th) & TH_SYN) == 0) 1476 return (0); 1477 1478 if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub && 1479 pf_pull_hdr(pd->m, pd->off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1480 /* Diddle with TCP options */ 1481 int hlen; 1482 opt = hdr + sizeof(struct tcphdr); 1483 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1484 while (hlen >= TCPOLEN_TIMESTAMP) { 1485 switch (*opt) { 1486 case TCPOPT_EOL: /* FALLTHROUGH */ 1487 case TCPOPT_NOP: 1488 opt++; 1489 hlen--; 1490 break; 1491 case TCPOPT_TIMESTAMP: 1492 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1493 src->scrub->pfss_flags |= 1494 PFSS_TIMESTAMP; 1495 src->scrub->pfss_ts_mod = 1496 arc4random(); 1497 1498 /* note PFSS_PAWS not set yet */ 1499 memcpy(&tsval, &opt[2], 1500 sizeof(u_int32_t)); 1501 memcpy(&tsecr, &opt[6], 1502 sizeof(u_int32_t)); 1503 src->scrub->pfss_tsval0 = ntohl(tsval); 1504 src->scrub->pfss_tsval = ntohl(tsval); 1505 src->scrub->pfss_tsecr = ntohl(tsecr); 1506 getmicrouptime(&src->scrub->pfss_last); 1507 } 1508 /* FALLTHROUGH */ 1509 default: 1510 hlen -= MAX(opt[1], 2); 1511 opt += MAX(opt[1], 2); 1512 break; 1513 } 1514 } 1515 } 1516 1517 return (0); 1518 } 1519 1520 void 1521 pf_normalize_tcp_cleanup(struct pf_kstate *state) 1522 { 1523 /* XXX Note: this also cleans up SCTP. */ 1524 uma_zfree(V_pf_state_scrub_z, state->src.scrub); 1525 uma_zfree(V_pf_state_scrub_z, state->dst.scrub); 1526 1527 /* Someday... flush the TCP segment reassembly descriptors. */ 1528 } 1529 int 1530 pf_normalize_sctp_init(struct pf_pdesc *pd, struct pf_state_peer *src, 1531 struct pf_state_peer *dst) 1532 { 1533 src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT); 1534 if (src->scrub == NULL) 1535 return (1); 1536 1537 dst->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT); 1538 if (dst->scrub == NULL) { 1539 uma_zfree(V_pf_state_scrub_z, src); 1540 return (1); 1541 } 1542 1543 dst->scrub->pfss_v_tag = pd->sctp_initiate_tag; 1544 1545 return (0); 1546 } 1547 1548 int 1549 pf_normalize_tcp_stateful(struct pf_pdesc *pd, 1550 u_short *reason, struct tcphdr *th, struct pf_kstate *state, 1551 struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback) 1552 { 1553 struct timeval uptime; 1554 u_int32_t tsval, tsecr; 1555 u_int tsval_from_last; 1556 u_int8_t hdr[60]; 1557 u_int8_t *opt; 1558 int copyback = 0; 1559 int got_ts = 0; 1560 size_t startoff; 1561 1562 KASSERT((src->scrub || dst->scrub), 1563 ("%s: src->scrub && dst->scrub!", __func__)); 1564 1565 /* 1566 * Enforce the minimum TTL seen for this connection. Negate a common 1567 * technique to evade an intrusion detection system and confuse 1568 * firewall state code. 1569 */ 1570 switch (pd->af) { 1571 #ifdef INET 1572 case AF_INET: { 1573 if (src->scrub) { 1574 struct ip *h = mtod(pd->m, struct ip *); 1575 if (h->ip_ttl > src->scrub->pfss_ttl) 1576 src->scrub->pfss_ttl = h->ip_ttl; 1577 h->ip_ttl = src->scrub->pfss_ttl; 1578 } 1579 break; 1580 } 1581 #endif /* INET */ 1582 #ifdef INET6 1583 case AF_INET6: { 1584 if (src->scrub) { 1585 struct ip6_hdr *h = mtod(pd->m, struct ip6_hdr *); 1586 if (h->ip6_hlim > src->scrub->pfss_ttl) 1587 src->scrub->pfss_ttl = h->ip6_hlim; 1588 h->ip6_hlim = src->scrub->pfss_ttl; 1589 } 1590 break; 1591 } 1592 #endif /* INET6 */ 1593 default: 1594 unhandled_af(pd->af); 1595 } 1596 1597 if (th->th_off > (sizeof(struct tcphdr) >> 2) && 1598 ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) || 1599 (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) && 1600 pf_pull_hdr(pd->m, pd->off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1601 /* Diddle with TCP options */ 1602 int hlen; 1603 opt = hdr + sizeof(struct tcphdr); 1604 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1605 while (hlen >= TCPOLEN_TIMESTAMP) { 1606 startoff = opt - (hdr + sizeof(struct tcphdr)); 1607 switch (*opt) { 1608 case TCPOPT_EOL: /* FALLTHROUGH */ 1609 case TCPOPT_NOP: 1610 opt++; 1611 hlen--; 1612 break; 1613 case TCPOPT_TIMESTAMP: 1614 /* Modulate the timestamps. Can be used for 1615 * NAT detection, OS uptime determination or 1616 * reboot detection. 1617 */ 1618 1619 if (got_ts) { 1620 /* Huh? Multiple timestamps!? */ 1621 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1622 DPFPRINTF(("multiple TS??\n")); 1623 pf_print_state(state); 1624 printf("\n"); 1625 } 1626 REASON_SET(reason, PFRES_TS); 1627 return (PF_DROP); 1628 } 1629 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1630 memcpy(&tsval, &opt[2], 1631 sizeof(u_int32_t)); 1632 if (tsval && src->scrub && 1633 (src->scrub->pfss_flags & 1634 PFSS_TIMESTAMP)) { 1635 tsval = ntohl(tsval); 1636 pf_patch_32(pd, 1637 &opt[2], 1638 htonl(tsval + 1639 src->scrub->pfss_ts_mod), 1640 PF_ALGNMNT(startoff)); 1641 copyback = 1; 1642 } 1643 1644 /* Modulate TS reply iff valid (!0) */ 1645 memcpy(&tsecr, &opt[6], 1646 sizeof(u_int32_t)); 1647 if (tsecr && dst->scrub && 1648 (dst->scrub->pfss_flags & 1649 PFSS_TIMESTAMP)) { 1650 tsecr = ntohl(tsecr) 1651 - dst->scrub->pfss_ts_mod; 1652 pf_patch_32(pd, 1653 &opt[6], 1654 htonl(tsecr), 1655 PF_ALGNMNT(startoff)); 1656 copyback = 1; 1657 } 1658 got_ts = 1; 1659 } 1660 /* FALLTHROUGH */ 1661 default: 1662 hlen -= MAX(opt[1], 2); 1663 opt += MAX(opt[1], 2); 1664 break; 1665 } 1666 } 1667 if (copyback) { 1668 /* Copyback the options, caller copys back header */ 1669 *writeback = 1; 1670 m_copyback(pd->m, pd->off + sizeof(struct tcphdr), 1671 (th->th_off << 2) - sizeof(struct tcphdr), hdr + 1672 sizeof(struct tcphdr)); 1673 } 1674 } 1675 1676 /* 1677 * Must invalidate PAWS checks on connections idle for too long. 1678 * The fastest allowed timestamp clock is 1ms. That turns out to 1679 * be about 24 days before it wraps. XXX Right now our lowerbound 1680 * TS echo check only works for the first 12 days of a connection 1681 * when the TS has exhausted half its 32bit space 1682 */ 1683 #define TS_MAX_IDLE (24*24*60*60) 1684 #define TS_MAX_CONN (12*24*60*60) /* XXX remove when better tsecr check */ 1685 1686 getmicrouptime(&uptime); 1687 if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) && 1688 (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE || 1689 time_uptime - (state->creation / 1000) > TS_MAX_CONN)) { 1690 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1691 DPFPRINTF(("src idled out of PAWS\n")); 1692 pf_print_state(state); 1693 printf("\n"); 1694 } 1695 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS) 1696 | PFSS_PAWS_IDLED; 1697 } 1698 if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) && 1699 uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) { 1700 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1701 DPFPRINTF(("dst idled out of PAWS\n")); 1702 pf_print_state(state); 1703 printf("\n"); 1704 } 1705 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS) 1706 | PFSS_PAWS_IDLED; 1707 } 1708 1709 if (got_ts && src->scrub && dst->scrub && 1710 (src->scrub->pfss_flags & PFSS_PAWS) && 1711 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1712 /* Validate that the timestamps are "in-window". 1713 * RFC1323 describes TCP Timestamp options that allow 1714 * measurement of RTT (round trip time) and PAWS 1715 * (protection against wrapped sequence numbers). PAWS 1716 * gives us a set of rules for rejecting packets on 1717 * long fat pipes (packets that were somehow delayed 1718 * in transit longer than the time it took to send the 1719 * full TCP sequence space of 4Gb). We can use these 1720 * rules and infer a few others that will let us treat 1721 * the 32bit timestamp and the 32bit echoed timestamp 1722 * as sequence numbers to prevent a blind attacker from 1723 * inserting packets into a connection. 1724 * 1725 * RFC1323 tells us: 1726 * - The timestamp on this packet must be greater than 1727 * or equal to the last value echoed by the other 1728 * endpoint. The RFC says those will be discarded 1729 * since it is a dup that has already been acked. 1730 * This gives us a lowerbound on the timestamp. 1731 * timestamp >= other last echoed timestamp 1732 * - The timestamp will be less than or equal to 1733 * the last timestamp plus the time between the 1734 * last packet and now. The RFC defines the max 1735 * clock rate as 1ms. We will allow clocks to be 1736 * up to 10% fast and will allow a total difference 1737 * or 30 seconds due to a route change. And this 1738 * gives us an upperbound on the timestamp. 1739 * timestamp <= last timestamp + max ticks 1740 * We have to be careful here. Windows will send an 1741 * initial timestamp of zero and then initialize it 1742 * to a random value after the 3whs; presumably to 1743 * avoid a DoS by having to call an expensive RNG 1744 * during a SYN flood. Proof MS has at least one 1745 * good security geek. 1746 * 1747 * - The TCP timestamp option must also echo the other 1748 * endpoints timestamp. The timestamp echoed is the 1749 * one carried on the earliest unacknowledged segment 1750 * on the left edge of the sequence window. The RFC 1751 * states that the host will reject any echoed 1752 * timestamps that were larger than any ever sent. 1753 * This gives us an upperbound on the TS echo. 1754 * tescr <= largest_tsval 1755 * - The lowerbound on the TS echo is a little more 1756 * tricky to determine. The other endpoint's echoed 1757 * values will not decrease. But there may be 1758 * network conditions that re-order packets and 1759 * cause our view of them to decrease. For now the 1760 * only lowerbound we can safely determine is that 1761 * the TS echo will never be less than the original 1762 * TS. XXX There is probably a better lowerbound. 1763 * Remove TS_MAX_CONN with better lowerbound check. 1764 * tescr >= other original TS 1765 * 1766 * It is also important to note that the fastest 1767 * timestamp clock of 1ms will wrap its 32bit space in 1768 * 24 days. So we just disable TS checking after 24 1769 * days of idle time. We actually must use a 12d 1770 * connection limit until we can come up with a better 1771 * lowerbound to the TS echo check. 1772 */ 1773 struct timeval delta_ts; 1774 int ts_fudge; 1775 1776 /* 1777 * PFTM_TS_DIFF is how many seconds of leeway to allow 1778 * a host's timestamp. This can happen if the previous 1779 * packet got delayed in transit for much longer than 1780 * this packet. 1781 */ 1782 if ((ts_fudge = state->rule->timeout[PFTM_TS_DIFF]) == 0) 1783 ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF]; 1784 1785 /* Calculate max ticks since the last timestamp */ 1786 #define TS_MAXFREQ 1100 /* RFC max TS freq of 1Khz + 10% skew */ 1787 #define TS_MICROSECS 1000000 /* microseconds per second */ 1788 delta_ts = uptime; 1789 timevalsub(&delta_ts, &src->scrub->pfss_last); 1790 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ; 1791 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ); 1792 1793 if ((src->state >= TCPS_ESTABLISHED && 1794 dst->state >= TCPS_ESTABLISHED) && 1795 (SEQ_LT(tsval, dst->scrub->pfss_tsecr) || 1796 SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) || 1797 (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) || 1798 SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) { 1799 /* Bad RFC1323 implementation or an insertion attack. 1800 * 1801 * - Solaris 2.6 and 2.7 are known to send another ACK 1802 * after the FIN,FIN|ACK,ACK closing that carries 1803 * an old timestamp. 1804 */ 1805 1806 DPFPRINTF(("Timestamp failed %c%c%c%c\n", 1807 SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ', 1808 SEQ_GT(tsval, src->scrub->pfss_tsval + 1809 tsval_from_last) ? '1' : ' ', 1810 SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ', 1811 SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' ')); 1812 DPFPRINTF((" tsval: %u tsecr: %u +ticks: %u " 1813 "idle: %jus %lums\n", 1814 tsval, tsecr, tsval_from_last, 1815 (uintmax_t)delta_ts.tv_sec, 1816 delta_ts.tv_usec / 1000)); 1817 DPFPRINTF((" src->tsval: %u tsecr: %u\n", 1818 src->scrub->pfss_tsval, src->scrub->pfss_tsecr)); 1819 DPFPRINTF((" dst->tsval: %u tsecr: %u tsval0: %u" 1820 "\n", dst->scrub->pfss_tsval, 1821 dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0)); 1822 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1823 pf_print_state(state); 1824 pf_print_flags(tcp_get_flags(th)); 1825 printf("\n"); 1826 } 1827 REASON_SET(reason, PFRES_TS); 1828 return (PF_DROP); 1829 } 1830 1831 /* XXX I'd really like to require tsecr but it's optional */ 1832 1833 } else if (!got_ts && (tcp_get_flags(th) & TH_RST) == 0 && 1834 ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED) 1835 || pd->p_len > 0 || (tcp_get_flags(th) & TH_SYN)) && 1836 src->scrub && dst->scrub && 1837 (src->scrub->pfss_flags & PFSS_PAWS) && 1838 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1839 /* Didn't send a timestamp. Timestamps aren't really useful 1840 * when: 1841 * - connection opening or closing (often not even sent). 1842 * but we must not let an attacker to put a FIN on a 1843 * data packet to sneak it through our ESTABLISHED check. 1844 * - on a TCP reset. RFC suggests not even looking at TS. 1845 * - on an empty ACK. The TS will not be echoed so it will 1846 * probably not help keep the RTT calculation in sync and 1847 * there isn't as much danger when the sequence numbers 1848 * got wrapped. So some stacks don't include TS on empty 1849 * ACKs :-( 1850 * 1851 * To minimize the disruption to mostly RFC1323 conformant 1852 * stacks, we will only require timestamps on data packets. 1853 * 1854 * And what do ya know, we cannot require timestamps on data 1855 * packets. There appear to be devices that do legitimate 1856 * TCP connection hijacking. There are HTTP devices that allow 1857 * a 3whs (with timestamps) and then buffer the HTTP request. 1858 * If the intermediate device has the HTTP response cache, it 1859 * will spoof the response but not bother timestamping its 1860 * packets. So we can look for the presence of a timestamp in 1861 * the first data packet and if there, require it in all future 1862 * packets. 1863 */ 1864 1865 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) { 1866 /* 1867 * Hey! Someone tried to sneak a packet in. Or the 1868 * stack changed its RFC1323 behavior?!?! 1869 */ 1870 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1871 DPFPRINTF(("Did not receive expected RFC1323 " 1872 "timestamp\n")); 1873 pf_print_state(state); 1874 pf_print_flags(tcp_get_flags(th)); 1875 printf("\n"); 1876 } 1877 REASON_SET(reason, PFRES_TS); 1878 return (PF_DROP); 1879 } 1880 } 1881 1882 /* 1883 * We will note if a host sends his data packets with or without 1884 * timestamps. And require all data packets to contain a timestamp 1885 * if the first does. PAWS implicitly requires that all data packets be 1886 * timestamped. But I think there are middle-man devices that hijack 1887 * TCP streams immediately after the 3whs and don't timestamp their 1888 * packets (seen in a WWW accelerator or cache). 1889 */ 1890 if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags & 1891 (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) { 1892 if (got_ts) 1893 src->scrub->pfss_flags |= PFSS_DATA_TS; 1894 else { 1895 src->scrub->pfss_flags |= PFSS_DATA_NOTS; 1896 if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub && 1897 (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) { 1898 /* Don't warn if other host rejected RFC1323 */ 1899 DPFPRINTF(("Broken RFC1323 stack did not " 1900 "timestamp data packet. Disabled PAWS " 1901 "security.\n")); 1902 pf_print_state(state); 1903 pf_print_flags(tcp_get_flags(th)); 1904 printf("\n"); 1905 } 1906 } 1907 } 1908 1909 /* 1910 * Update PAWS values 1911 */ 1912 if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags & 1913 (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) { 1914 getmicrouptime(&src->scrub->pfss_last); 1915 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) || 1916 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 1917 src->scrub->pfss_tsval = tsval; 1918 1919 if (tsecr) { 1920 if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) || 1921 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 1922 src->scrub->pfss_tsecr = tsecr; 1923 1924 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 && 1925 (SEQ_LT(tsval, src->scrub->pfss_tsval0) || 1926 src->scrub->pfss_tsval0 == 0)) { 1927 /* tsval0 MUST be the lowest timestamp */ 1928 src->scrub->pfss_tsval0 = tsval; 1929 } 1930 1931 /* Only fully initialized after a TS gets echoed */ 1932 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0) 1933 src->scrub->pfss_flags |= PFSS_PAWS; 1934 } 1935 } 1936 1937 /* I have a dream.... TCP segment reassembly.... */ 1938 return (0); 1939 } 1940 1941 int 1942 pf_normalize_mss(struct pf_pdesc *pd) 1943 { 1944 struct tcphdr *th = &pd->hdr.tcp; 1945 u_int16_t *mss; 1946 int thoff; 1947 int opt, cnt, optlen = 0; 1948 u_char opts[TCP_MAXOLEN]; 1949 u_char *optp = opts; 1950 size_t startoff; 1951 1952 thoff = th->th_off << 2; 1953 cnt = thoff - sizeof(struct tcphdr); 1954 1955 if (cnt <= 0 || cnt > MAX_TCPOPTLEN || !pf_pull_hdr(pd->m, 1956 pd->off + sizeof(*th), opts, cnt, NULL, NULL, pd->af)) 1957 return (0); 1958 1959 for (; cnt > 0; cnt -= optlen, optp += optlen) { 1960 startoff = optp - opts; 1961 opt = optp[0]; 1962 if (opt == TCPOPT_EOL) 1963 break; 1964 if (opt == TCPOPT_NOP) 1965 optlen = 1; 1966 else { 1967 if (cnt < 2) 1968 break; 1969 optlen = optp[1]; 1970 if (optlen < 2 || optlen > cnt) 1971 break; 1972 } 1973 switch (opt) { 1974 case TCPOPT_MAXSEG: 1975 mss = (u_int16_t *)(optp + 2); 1976 if ((ntohs(*mss)) > pd->act.max_mss) { 1977 pf_patch_16(pd, 1978 mss, htons(pd->act.max_mss), 1979 PF_ALGNMNT(startoff)); 1980 m_copyback(pd->m, pd->off + sizeof(*th), 1981 thoff - sizeof(*th), opts); 1982 m_copyback(pd->m, pd->off, sizeof(*th), (caddr_t)th); 1983 } 1984 break; 1985 default: 1986 break; 1987 } 1988 } 1989 1990 return (0); 1991 } 1992 1993 int 1994 pf_scan_sctp(struct pf_pdesc *pd) 1995 { 1996 struct sctp_chunkhdr ch = { }; 1997 int chunk_off = sizeof(struct sctphdr); 1998 int chunk_start; 1999 int ret; 2000 2001 while (pd->off + chunk_off < pd->tot_len) { 2002 if (!pf_pull_hdr(pd->m, pd->off + chunk_off, &ch, sizeof(ch), NULL, 2003 NULL, pd->af)) 2004 return (PF_DROP); 2005 2006 /* Length includes the header, this must be at least 4. */ 2007 if (ntohs(ch.chunk_length) < 4) 2008 return (PF_DROP); 2009 2010 chunk_start = chunk_off; 2011 chunk_off += roundup(ntohs(ch.chunk_length), 4); 2012 2013 switch (ch.chunk_type) { 2014 case SCTP_INITIATION: 2015 case SCTP_INITIATION_ACK: { 2016 struct sctp_init_chunk init; 2017 2018 if (!pf_pull_hdr(pd->m, pd->off + chunk_start, &init, 2019 sizeof(init), NULL, NULL, pd->af)) 2020 return (PF_DROP); 2021 2022 /* 2023 * RFC 9620, Section 3.3.2, "The Initiate Tag is allowed to have 2024 * any value except 0." 2025 */ 2026 if (init.init.initiate_tag == 0) 2027 return (PF_DROP); 2028 if (init.init.num_inbound_streams == 0) 2029 return (PF_DROP); 2030 if (init.init.num_outbound_streams == 0) 2031 return (PF_DROP); 2032 if (ntohl(init.init.a_rwnd) < SCTP_MIN_RWND) 2033 return (PF_DROP); 2034 2035 /* 2036 * RFC 9260, Section 3.1, INIT chunks MUST have zero 2037 * verification tag. 2038 */ 2039 if (ch.chunk_type == SCTP_INITIATION && 2040 pd->hdr.sctp.v_tag != 0) 2041 return (PF_DROP); 2042 2043 pd->sctp_initiate_tag = init.init.initiate_tag; 2044 2045 if (ch.chunk_type == SCTP_INITIATION) 2046 pd->sctp_flags |= PFDESC_SCTP_INIT; 2047 else 2048 pd->sctp_flags |= PFDESC_SCTP_INIT_ACK; 2049 2050 ret = pf_multihome_scan_init(pd->off + chunk_start, 2051 ntohs(init.ch.chunk_length), pd); 2052 if (ret != PF_PASS) 2053 return (ret); 2054 2055 break; 2056 } 2057 case SCTP_ABORT_ASSOCIATION: 2058 pd->sctp_flags |= PFDESC_SCTP_ABORT; 2059 break; 2060 case SCTP_SHUTDOWN: 2061 case SCTP_SHUTDOWN_ACK: 2062 pd->sctp_flags |= PFDESC_SCTP_SHUTDOWN; 2063 break; 2064 case SCTP_SHUTDOWN_COMPLETE: 2065 pd->sctp_flags |= PFDESC_SCTP_SHUTDOWN_COMPLETE; 2066 break; 2067 case SCTP_COOKIE_ECHO: 2068 pd->sctp_flags |= PFDESC_SCTP_COOKIE; 2069 break; 2070 case SCTP_COOKIE_ACK: 2071 pd->sctp_flags |= PFDESC_SCTP_COOKIE_ACK; 2072 break; 2073 case SCTP_DATA: 2074 pd->sctp_flags |= PFDESC_SCTP_DATA; 2075 break; 2076 case SCTP_HEARTBEAT_REQUEST: 2077 pd->sctp_flags |= PFDESC_SCTP_HEARTBEAT; 2078 break; 2079 case SCTP_HEARTBEAT_ACK: 2080 pd->sctp_flags |= PFDESC_SCTP_HEARTBEAT_ACK; 2081 break; 2082 case SCTP_ASCONF: 2083 pd->sctp_flags |= PFDESC_SCTP_ASCONF; 2084 2085 ret = pf_multihome_scan_asconf(pd->off + chunk_start, 2086 ntohs(ch.chunk_length), pd); 2087 if (ret != PF_PASS) 2088 return (ret); 2089 break; 2090 default: 2091 pd->sctp_flags |= PFDESC_SCTP_OTHER; 2092 break; 2093 } 2094 } 2095 2096 /* Validate chunk lengths vs. packet length. */ 2097 if (pd->off + chunk_off != pd->tot_len) 2098 return (PF_DROP); 2099 2100 /* 2101 * INIT, INIT_ACK or SHUTDOWN_COMPLETE chunks must always be the only 2102 * one in a packet. 2103 */ 2104 if ((pd->sctp_flags & PFDESC_SCTP_INIT) && 2105 (pd->sctp_flags & ~PFDESC_SCTP_INIT)) 2106 return (PF_DROP); 2107 if ((pd->sctp_flags & PFDESC_SCTP_INIT_ACK) && 2108 (pd->sctp_flags & ~PFDESC_SCTP_INIT_ACK)) 2109 return (PF_DROP); 2110 if ((pd->sctp_flags & PFDESC_SCTP_SHUTDOWN_COMPLETE) && 2111 (pd->sctp_flags & ~PFDESC_SCTP_SHUTDOWN_COMPLETE)) 2112 return (PF_DROP); 2113 if ((pd->sctp_flags & PFDESC_SCTP_ABORT) && 2114 (pd->sctp_flags & PFDESC_SCTP_DATA)) { 2115 /* 2116 * RFC4960 3.3.7: DATA chunks MUST NOT be 2117 * bundled with ABORT. 2118 */ 2119 return (PF_DROP); 2120 } 2121 2122 return (PF_PASS); 2123 } 2124 2125 int 2126 pf_normalize_sctp(struct pf_pdesc *pd) 2127 { 2128 struct pf_krule *r, *rm = NULL; 2129 struct sctphdr *sh = &pd->hdr.sctp; 2130 u_short reason; 2131 sa_family_t af = pd->af; 2132 int srs; 2133 2134 PF_RULES_RASSERT(); 2135 2136 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 2137 /* Check if there any scrub rules. Lack of scrub rules means enforced 2138 * packet normalization operation just like in OpenBSD. */ 2139 srs = (r != NULL); 2140 while (r != NULL) { 2141 pf_counter_u64_add(&r->evaluations, 1); 2142 if (pfi_kkif_match(r->kif, pd->kif) == r->ifnot) 2143 r = r->skip[PF_SKIP_IFP]; 2144 else if (r->direction && r->direction != pd->dir) 2145 r = r->skip[PF_SKIP_DIR]; 2146 else if (r->af && r->af != af) 2147 r = r->skip[PF_SKIP_AF]; 2148 else if (r->proto && r->proto != pd->proto) 2149 r = r->skip[PF_SKIP_PROTO]; 2150 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, 2151 r->src.neg, pd->kif, M_GETFIB(pd->m))) 2152 r = r->skip[PF_SKIP_SRC_ADDR]; 2153 else if (r->src.port_op && !pf_match_port(r->src.port_op, 2154 r->src.port[0], r->src.port[1], sh->src_port)) 2155 r = r->skip[PF_SKIP_SRC_PORT]; 2156 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, 2157 r->dst.neg, NULL, M_GETFIB(pd->m))) 2158 r = r->skip[PF_SKIP_DST_ADDR]; 2159 else if (r->dst.port_op && !pf_match_port(r->dst.port_op, 2160 r->dst.port[0], r->dst.port[1], sh->dest_port)) 2161 r = r->skip[PF_SKIP_DST_PORT]; 2162 else { 2163 rm = r; 2164 break; 2165 } 2166 } 2167 2168 if (srs) { 2169 /* With scrub rules present SCTP normalization happens only 2170 * if one of rules has matched and it's not a "no scrub" rule */ 2171 if (rm == NULL || rm->action == PF_NOSCRUB) 2172 return (PF_PASS); 2173 2174 pf_counter_u64_critical_enter(); 2175 pf_counter_u64_add_protected(&r->packets[pd->dir == PF_OUT], 1); 2176 pf_counter_u64_add_protected(&r->bytes[pd->dir == PF_OUT], pd->tot_len); 2177 pf_counter_u64_critical_exit(); 2178 } 2179 2180 /* Verify we're a multiple of 4 bytes long */ 2181 if ((pd->tot_len - pd->off - sizeof(struct sctphdr)) % 4) 2182 goto sctp_drop; 2183 2184 /* INIT chunk needs to be the only chunk */ 2185 if (pd->sctp_flags & PFDESC_SCTP_INIT) 2186 if (pd->sctp_flags & ~PFDESC_SCTP_INIT) 2187 goto sctp_drop; 2188 2189 return (PF_PASS); 2190 2191 sctp_drop: 2192 REASON_SET(&reason, PFRES_NORM); 2193 if (rm != NULL && r->log) 2194 PFLOG_PACKET(PF_DROP, reason, r, NULL, NULL, pd, 2195 1, NULL); 2196 2197 return (PF_DROP); 2198 } 2199 2200 #if defined(INET) || defined(INET6) 2201 void 2202 pf_scrub(struct pf_pdesc *pd) 2203 { 2204 2205 struct ip *h = mtod(pd->m, struct ip *); 2206 #ifdef INET6 2207 struct ip6_hdr *h6 = mtod(pd->m, struct ip6_hdr *); 2208 #endif /* INET6 */ 2209 2210 /* Clear IP_DF if no-df was requested */ 2211 if (pd->af == AF_INET && pd->act.flags & PFSTATE_NODF && 2212 h->ip_off & htons(IP_DF)) 2213 { 2214 u_int16_t ip_off = h->ip_off; 2215 2216 h->ip_off &= htons(~IP_DF); 2217 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 2218 } 2219 2220 /* Enforce a minimum ttl, may cause endless packet loops */ 2221 if (pd->af == AF_INET && pd->act.min_ttl && 2222 h->ip_ttl < pd->act.min_ttl) { 2223 u_int16_t ip_ttl = h->ip_ttl; 2224 2225 h->ip_ttl = pd->act.min_ttl; 2226 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0); 2227 } 2228 #ifdef INET6 2229 /* Enforce a minimum ttl, may cause endless packet loops */ 2230 if (pd->af == AF_INET6 && pd->act.min_ttl && 2231 h6->ip6_hlim < pd->act.min_ttl) 2232 h6->ip6_hlim = pd->act.min_ttl; 2233 #endif /* INET6 */ 2234 /* Enforce tos */ 2235 if (pd->act.flags & PFSTATE_SETTOS) { 2236 switch (pd->af) { 2237 case AF_INET: { 2238 u_int16_t ov, nv; 2239 2240 ov = *(u_int16_t *)h; 2241 h->ip_tos = pd->act.set_tos | (h->ip_tos & IPTOS_ECN_MASK); 2242 nv = *(u_int16_t *)h; 2243 2244 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0); 2245 break; 2246 } 2247 #ifdef INET6 2248 case AF_INET6: 2249 h6->ip6_flow &= IPV6_FLOWLABEL_MASK | IPV6_VERSION_MASK; 2250 h6->ip6_flow |= htonl((pd->act.set_tos | IPV6_ECN(h6)) << 20); 2251 break; 2252 #endif /* INET6 */ 2253 } 2254 } 2255 2256 /* random-id, but not for fragments */ 2257 #ifdef INET 2258 if (pd->af == AF_INET && 2259 pd->act.flags & PFSTATE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) { 2260 uint16_t ip_id = h->ip_id; 2261 2262 ip_fillid(h, V_ip_random_id); 2263 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0); 2264 } 2265 #endif /* INET */ 2266 } 2267 #endif /* INET || INET6 */ 2268