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 RB_HEAD(pf_frag_tree, pf_fragment); 80 struct pf_frnode { 81 struct pf_addr fn_src; /* ip source address */ 82 struct pf_addr fn_dst; /* ip destination address */ 83 sa_family_t fn_af; /* address family */ 84 u_int8_t fn_proto; /* protocol for fragments in fn_tree */ 85 u_int32_t fn_fragments; /* number of entries in fn_tree */ 86 87 RB_ENTRY(pf_frnode) fn_entry; 88 struct pf_frag_tree fn_tree; /* matching fragments, lookup by id */ 89 }; 90 91 struct pf_fragment { 92 uint32_t fr_id; /* fragment id for reassemble */ 93 94 /* pointers to queue element */ 95 struct pf_frent *fr_firstoff[PF_FRAG_ENTRY_POINTS]; 96 /* count entries between pointers */ 97 uint8_t fr_entries[PF_FRAG_ENTRY_POINTS]; 98 RB_ENTRY(pf_fragment) fr_entry; 99 TAILQ_ENTRY(pf_fragment) frag_next; 100 uint32_t fr_timeout; 101 TAILQ_HEAD(pf_fragq, pf_frent) fr_queue; 102 uint16_t fr_maxlen; /* maximum length of single fragment */ 103 u_int16_t fr_holes; /* number of holes in the queue */ 104 struct pf_frnode *fr_node; /* ip src/dst/proto/af for fragments */ 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_frnode_z); 118 #define V_pf_frnode_z VNET(pf_frnode_z) 119 VNET_DEFINE_STATIC(uma_zone_t, pf_frag_z); 120 #define V_pf_frag_z VNET(pf_frag_z) 121 VNET_DEFINE(uma_zone_t, pf_anchor_z); 122 VNET_DEFINE(uma_zone_t, pf_eth_anchor_z); 123 124 TAILQ_HEAD(pf_fragqueue, pf_fragment); 125 TAILQ_HEAD(pf_cachequeue, pf_fragment); 126 RB_HEAD(pf_frnode_tree, pf_frnode); 127 VNET_DEFINE_STATIC(struct pf_fragqueue, pf_fragqueue); 128 #define V_pf_fragqueue VNET(pf_fragqueue) 129 static __inline int pf_frnode_compare(struct pf_frnode *, 130 struct pf_frnode *); 131 VNET_DEFINE_STATIC(struct pf_frnode_tree, pf_frnode_tree); 132 #define V_pf_frnode_tree VNET(pf_frnode_tree) 133 RB_PROTOTYPE(pf_frnode_tree, pf_frnode, fn_entry, pf_frnode_compare); 134 RB_GENERATE(pf_frnode_tree, pf_frnode, fn_entry, pf_frnode_compare); 135 136 static int pf_frag_compare(struct pf_fragment *, 137 struct pf_fragment *); 138 static RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 139 static RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 140 141 static void pf_flush_fragments(void); 142 static void pf_free_fragment(struct pf_fragment *); 143 144 static struct pf_frent *pf_create_fragment(u_short *); 145 static int pf_frent_holes(struct pf_frent *frent); 146 static struct pf_fragment *pf_find_fragment(struct pf_frnode *, u_int32_t); 147 static inline int pf_frent_index(struct pf_frent *); 148 static int pf_frent_insert(struct pf_fragment *, 149 struct pf_frent *, struct pf_frent *); 150 void pf_frent_remove(struct pf_fragment *, 151 struct pf_frent *); 152 struct pf_frent *pf_frent_previous(struct pf_fragment *, 153 struct pf_frent *); 154 static struct pf_fragment *pf_fillup_fragment(struct pf_frnode *, u_int32_t, 155 struct pf_frent *, u_short *); 156 static struct mbuf *pf_join_fragment(struct pf_fragment *); 157 #ifdef INET 158 static int pf_reassemble(struct mbuf **, u_short *); 159 #endif /* INET */ 160 #ifdef INET6 161 static int pf_reassemble6(struct mbuf **, 162 struct ip6_frag *, uint16_t, uint16_t, u_short *); 163 #endif /* INET6 */ 164 165 #ifdef INET 166 static void 167 pf_ip2key(struct ip *ip, struct pf_frnode *key) 168 { 169 170 key->fn_src.v4 = ip->ip_src; 171 key->fn_dst.v4 = ip->ip_dst; 172 key->fn_af = AF_INET; 173 key->fn_proto = ip->ip_p; 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_frnode_z = uma_zcreate("pf fragment node", 184 sizeof(struct pf_frnode), NULL, NULL, NULL, NULL, 185 UMA_ALIGN_PTR, 0); 186 V_pf_frent_z = uma_zcreate("pf frag entries", sizeof(struct pf_frent), 187 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 188 V_pf_state_scrub_z = uma_zcreate("pf state scrubs", 189 sizeof(struct pf_state_scrub), NULL, NULL, NULL, NULL, 190 UMA_ALIGN_PTR, 0); 191 192 mtx_init(&V_pf_frag_mtx, "pf fragments", NULL, MTX_DEF); 193 194 V_pf_limits[PF_LIMIT_FRAGS].zone = V_pf_frent_z; 195 V_pf_limits[PF_LIMIT_FRAGS].limit = PFFRAG_FRENT_HIWAT; 196 uma_zone_set_max(V_pf_frent_z, PFFRAG_FRENT_HIWAT); 197 uma_zone_set_warning(V_pf_frent_z, "PF frag entries limit reached"); 198 199 TAILQ_INIT(&V_pf_fragqueue); 200 } 201 202 void 203 pf_normalize_cleanup(void) 204 { 205 206 uma_zdestroy(V_pf_state_scrub_z); 207 uma_zdestroy(V_pf_frent_z); 208 uma_zdestroy(V_pf_frnode_z); 209 uma_zdestroy(V_pf_frag_z); 210 211 mtx_destroy(&V_pf_frag_mtx); 212 } 213 214 static int 215 pf_frnode_compare(struct pf_frnode *a, struct pf_frnode *b) 216 { 217 int diff; 218 219 if ((diff = a->fn_proto - b->fn_proto) != 0) 220 return (diff); 221 if ((diff = a->fn_af - b->fn_af) != 0) 222 return (diff); 223 if ((diff = pf_addr_cmp(&a->fn_src, &b->fn_src, a->fn_af)) != 0) 224 return (diff); 225 if ((diff = pf_addr_cmp(&a->fn_dst, &b->fn_dst, a->fn_af)) != 0) 226 return (diff); 227 return (0); 228 } 229 230 static __inline int 231 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b) 232 { 233 int diff; 234 235 if ((diff = a->fr_id - b->fr_id) != 0) 236 return (diff); 237 238 return (0); 239 } 240 241 void 242 pf_purge_expired_fragments(void) 243 { 244 u_int32_t expire = time_uptime - 245 V_pf_default_rule.timeout[PFTM_FRAG]; 246 247 pf_purge_fragments(expire); 248 } 249 250 void 251 pf_purge_fragments(uint32_t expire) 252 { 253 struct pf_fragment *frag; 254 255 PF_FRAG_LOCK(); 256 while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) { 257 if (frag->fr_timeout > expire) 258 break; 259 260 DPFPRINTF(PF_DEBUG_MISC, "expiring %d(%p)", 261 frag->fr_id, frag); 262 pf_free_fragment(frag); 263 } 264 265 PF_FRAG_UNLOCK(); 266 } 267 268 /* 269 * Try to flush old fragments to make space for new ones 270 */ 271 static void 272 pf_flush_fragments(void) 273 { 274 struct pf_fragment *frag; 275 int goal; 276 277 PF_FRAG_ASSERT(); 278 279 goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10; 280 DPFPRINTF(PF_DEBUG_MISC, "trying to free %d frag entriess", goal); 281 while (goal < uma_zone_get_cur(V_pf_frent_z)) { 282 frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue); 283 if (frag) 284 pf_free_fragment(frag); 285 else 286 break; 287 } 288 } 289 290 /* 291 * Remove a fragment from the fragment queue, free its fragment entries, 292 * and free the fragment itself. 293 */ 294 static void 295 pf_free_fragment(struct pf_fragment *frag) 296 { 297 struct pf_frent *frent; 298 struct pf_frnode *frnode; 299 300 PF_FRAG_ASSERT(); 301 302 frnode = frag->fr_node; 303 RB_REMOVE(pf_frag_tree, &frnode->fn_tree, frag); 304 MPASS(frnode->fn_fragments >= 1); 305 frnode->fn_fragments--; 306 if (frnode->fn_fragments == 0) { 307 MPASS(RB_EMPTY(&frnode->fn_tree)); 308 RB_REMOVE(pf_frnode_tree, &V_pf_frnode_tree, frnode); 309 uma_zfree(V_pf_frnode_z, frnode); 310 } 311 312 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next); 313 314 /* Free all fragment entries */ 315 while ((frent = TAILQ_FIRST(&frag->fr_queue)) != NULL) { 316 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 317 318 m_freem(frent->fe_m); 319 uma_zfree(V_pf_frent_z, frent); 320 } 321 322 uma_zfree(V_pf_frag_z, frag); 323 } 324 325 static struct pf_fragment * 326 pf_find_fragment(struct pf_frnode *key, uint32_t id) 327 { 328 struct pf_fragment *frag, idkey; 329 struct pf_frnode *frnode; 330 331 PF_FRAG_ASSERT(); 332 333 frnode = RB_FIND(pf_frnode_tree, &V_pf_frnode_tree, key); 334 if (frnode == NULL) 335 return (NULL); 336 MPASS(frnode->fn_fragments >= 1); 337 idkey.fr_id = id; 338 frag = RB_FIND(pf_frag_tree, &frnode->fn_tree, &idkey); 339 if (frag == NULL) 340 return (NULL); 341 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next); 342 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next); 343 344 return (frag); 345 } 346 347 static struct pf_frent * 348 pf_create_fragment(u_short *reason) 349 { 350 struct pf_frent *frent; 351 352 PF_FRAG_ASSERT(); 353 354 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT); 355 if (frent == NULL) { 356 pf_flush_fragments(); 357 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT); 358 if (frent == NULL) { 359 REASON_SET(reason, PFRES_MEMORY); 360 return (NULL); 361 } 362 } 363 364 return (frent); 365 } 366 367 /* 368 * Calculate the additional holes that were created in the fragment 369 * queue by inserting this fragment. A fragment in the middle 370 * creates one more hole by splitting. For each connected side, 371 * it loses one hole. 372 * Fragment entry must be in the queue when calling this function. 373 */ 374 static int 375 pf_frent_holes(struct pf_frent *frent) 376 { 377 struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next); 378 struct pf_frent *next = TAILQ_NEXT(frent, fr_next); 379 int holes = 1; 380 381 if (prev == NULL) { 382 if (frent->fe_off == 0) 383 holes--; 384 } else { 385 KASSERT(frent->fe_off != 0, ("frent->fe_off != 0")); 386 if (frent->fe_off == prev->fe_off + prev->fe_len) 387 holes--; 388 } 389 if (next == NULL) { 390 if (!frent->fe_mff) 391 holes--; 392 } else { 393 KASSERT(frent->fe_mff, ("frent->fe_mff")); 394 if (next->fe_off == frent->fe_off + frent->fe_len) 395 holes--; 396 } 397 return holes; 398 } 399 400 static inline int 401 pf_frent_index(struct pf_frent *frent) 402 { 403 /* 404 * We have an array of 16 entry points to the queue. A full size 405 * 65535 octet IP packet can have 8192 fragments. So the queue 406 * traversal length is at most 512 and at most 16 entry points are 407 * checked. We need 128 additional bytes on a 64 bit architecture. 408 */ 409 CTASSERT(((u_int16_t)0xffff &~ 7) / (0x10000 / PF_FRAG_ENTRY_POINTS) == 410 16 - 1); 411 CTASSERT(((u_int16_t)0xffff >> 3) / PF_FRAG_ENTRY_POINTS == 512 - 1); 412 413 return frent->fe_off / (0x10000 / PF_FRAG_ENTRY_POINTS); 414 } 415 416 static int 417 pf_frent_insert(struct pf_fragment *frag, struct pf_frent *frent, 418 struct pf_frent *prev) 419 { 420 int index; 421 422 CTASSERT(PF_FRAG_ENTRY_LIMIT <= 0xff); 423 424 /* 425 * A packet has at most 65536 octets. With 16 entry points, each one 426 * spawns 4096 octets. We limit these to 64 fragments each, which 427 * means on average every fragment must have at least 64 octets. 428 */ 429 index = pf_frent_index(frent); 430 if (frag->fr_entries[index] >= PF_FRAG_ENTRY_LIMIT) 431 return ENOBUFS; 432 frag->fr_entries[index]++; 433 434 if (prev == NULL) { 435 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next); 436 } else { 437 KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off, 438 ("overlapping fragment")); 439 TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next); 440 } 441 442 if (frag->fr_firstoff[index] == NULL) { 443 KASSERT(prev == NULL || pf_frent_index(prev) < index, 444 ("prev == NULL || pf_frent_index(pref) < index")); 445 frag->fr_firstoff[index] = frent; 446 } else { 447 if (frent->fe_off < frag->fr_firstoff[index]->fe_off) { 448 KASSERT(prev == NULL || pf_frent_index(prev) < index, 449 ("prev == NULL || pf_frent_index(pref) < index")); 450 frag->fr_firstoff[index] = frent; 451 } else { 452 KASSERT(prev != NULL, ("prev != NULL")); 453 KASSERT(pf_frent_index(prev) == index, 454 ("pf_frent_index(prev) == index")); 455 } 456 } 457 458 frag->fr_holes += pf_frent_holes(frent); 459 460 return 0; 461 } 462 463 void 464 pf_frent_remove(struct pf_fragment *frag, struct pf_frent *frent) 465 { 466 #ifdef INVARIANTS 467 struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next); 468 #endif /* INVARIANTS */ 469 struct pf_frent *next = TAILQ_NEXT(frent, fr_next); 470 int index; 471 472 frag->fr_holes -= pf_frent_holes(frent); 473 474 index = pf_frent_index(frent); 475 KASSERT(frag->fr_firstoff[index] != NULL, ("frent not found")); 476 if (frag->fr_firstoff[index]->fe_off == frent->fe_off) { 477 if (next == NULL) { 478 frag->fr_firstoff[index] = NULL; 479 } else { 480 KASSERT(frent->fe_off + frent->fe_len <= next->fe_off, 481 ("overlapping fragment")); 482 if (pf_frent_index(next) == index) { 483 frag->fr_firstoff[index] = next; 484 } else { 485 frag->fr_firstoff[index] = NULL; 486 } 487 } 488 } else { 489 KASSERT(frag->fr_firstoff[index]->fe_off < frent->fe_off, 490 ("frag->fr_firstoff[index]->fe_off < frent->fe_off")); 491 KASSERT(prev != NULL, ("prev != NULL")); 492 KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off, 493 ("overlapping fragment")); 494 KASSERT(pf_frent_index(prev) == index, 495 ("pf_frent_index(prev) == index")); 496 } 497 498 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 499 500 KASSERT(frag->fr_entries[index] > 0, ("No fragments remaining")); 501 frag->fr_entries[index]--; 502 } 503 504 struct pf_frent * 505 pf_frent_previous(struct pf_fragment *frag, struct pf_frent *frent) 506 { 507 struct pf_frent *prev, *next; 508 int index; 509 510 /* 511 * If there are no fragments after frag, take the final one. Assume 512 * that the global queue is not empty. 513 */ 514 prev = TAILQ_LAST(&frag->fr_queue, pf_fragq); 515 KASSERT(prev != NULL, ("prev != NULL")); 516 if (prev->fe_off <= frent->fe_off) 517 return prev; 518 /* 519 * We want to find a fragment entry that is before frag, but still 520 * close to it. Find the first fragment entry that is in the same 521 * entry point or in the first entry point after that. As we have 522 * already checked that there are entries behind frag, this will 523 * succeed. 524 */ 525 for (index = pf_frent_index(frent); index < PF_FRAG_ENTRY_POINTS; 526 index++) { 527 prev = frag->fr_firstoff[index]; 528 if (prev != NULL) 529 break; 530 } 531 KASSERT(prev != NULL, ("prev != NULL")); 532 /* 533 * In prev we may have a fragment from the same entry point that is 534 * before frent, or one that is just one position behind frent. 535 * In the latter case, we go back one step and have the predecessor. 536 * There may be none if the new fragment will be the first one. 537 */ 538 if (prev->fe_off > frent->fe_off) { 539 prev = TAILQ_PREV(prev, pf_fragq, fr_next); 540 if (prev == NULL) 541 return NULL; 542 KASSERT(prev->fe_off <= frent->fe_off, 543 ("prev->fe_off <= frent->fe_off")); 544 return prev; 545 } 546 /* 547 * In prev is the first fragment of the entry point. The offset 548 * of frag is behind it. Find the closest previous fragment. 549 */ 550 for (next = TAILQ_NEXT(prev, fr_next); next != NULL; 551 next = TAILQ_NEXT(next, fr_next)) { 552 if (next->fe_off > frent->fe_off) 553 break; 554 prev = next; 555 } 556 return prev; 557 } 558 559 static struct pf_fragment * 560 pf_fillup_fragment(struct pf_frnode *key, uint32_t id, 561 struct pf_frent *frent, u_short *reason) 562 { 563 struct pf_frent *after, *next, *prev; 564 struct pf_fragment *frag; 565 struct pf_frnode *frnode; 566 uint16_t total; 567 568 PF_FRAG_ASSERT(); 569 570 /* No empty fragments. */ 571 if (frent->fe_len == 0) { 572 DPFPRINTF(PF_DEBUG_MISC, "bad fragment: len 0"); 573 goto bad_fragment; 574 } 575 576 /* All fragments are 8 byte aligned. */ 577 if (frent->fe_mff && (frent->fe_len & 0x7)) { 578 DPFPRINTF(PF_DEBUG_MISC, "bad fragment: mff and len %d", 579 frent->fe_len); 580 goto bad_fragment; 581 } 582 583 /* Respect maximum length, IP_MAXPACKET == IPV6_MAXPACKET. */ 584 if (frent->fe_off + frent->fe_len > IP_MAXPACKET) { 585 DPFPRINTF(PF_DEBUG_MISC, "bad fragment: max packet %d", 586 frent->fe_off + frent->fe_len); 587 goto bad_fragment; 588 } 589 590 if (key->fn_af == AF_INET) 591 DPFPRINTF(PF_DEBUG_MISC, "reass frag %d @ %d-%d\n", 592 id, frent->fe_off, frent->fe_off + frent->fe_len); 593 else 594 DPFPRINTF(PF_DEBUG_MISC, "reass frag %#08x @ %d-%d", 595 id, frent->fe_off, frent->fe_off + frent->fe_len); 596 597 /* Fully buffer all of the fragments in this fragment queue. */ 598 frag = pf_find_fragment(key, id); 599 600 /* Create a new reassembly queue for this packet. */ 601 if (frag == NULL) { 602 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 603 if (frag == NULL) { 604 pf_flush_fragments(); 605 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 606 if (frag == NULL) { 607 REASON_SET(reason, PFRES_MEMORY); 608 goto drop_fragment; 609 } 610 } 611 612 frnode = RB_FIND(pf_frnode_tree, &V_pf_frnode_tree, key); 613 if (frnode == NULL) { 614 frnode = uma_zalloc(V_pf_frnode_z, M_NOWAIT); 615 if (frnode == NULL) { 616 pf_flush_fragments(); 617 frnode = uma_zalloc(V_pf_frnode_z, M_NOWAIT); 618 if (frnode == NULL) { 619 REASON_SET(reason, PFRES_MEMORY); 620 uma_zfree(V_pf_frag_z, frag); 621 goto drop_fragment; 622 } 623 } 624 *frnode = *key; 625 RB_INIT(&frnode->fn_tree); 626 frnode->fn_fragments = 0; 627 } 628 memset(frag->fr_firstoff, 0, sizeof(frag->fr_firstoff)); 629 memset(frag->fr_entries, 0, sizeof(frag->fr_entries)); 630 frag->fr_timeout = time_uptime; 631 TAILQ_INIT(&frag->fr_queue); 632 frag->fr_maxlen = frent->fe_len; 633 frag->fr_holes = 1; 634 635 frag->fr_id = id; 636 frag->fr_node = frnode; 637 /* RB_INSERT cannot fail as pf_find_fragment() found nothing */ 638 RB_INSERT(pf_frag_tree, &frnode->fn_tree, frag); 639 frnode->fn_fragments++; 640 if (frnode->fn_fragments == 1) 641 RB_INSERT(pf_frnode_tree, &V_pf_frnode_tree, frnode); 642 643 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next); 644 645 /* We do not have a previous fragment, cannot fail. */ 646 pf_frent_insert(frag, frent, NULL); 647 648 return (frag); 649 } 650 651 KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue")); 652 MPASS(frag->fr_node); 653 654 /* Remember maximum fragment len for refragmentation. */ 655 if (frent->fe_len > frag->fr_maxlen) 656 frag->fr_maxlen = frent->fe_len; 657 658 /* Maximum data we have seen already. */ 659 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 660 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 661 662 /* Non terminal fragments must have more fragments flag. */ 663 if (frent->fe_off + frent->fe_len < total && !frent->fe_mff) 664 goto free_ipv6_fragment; 665 666 /* Check if we saw the last fragment already. */ 667 if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) { 668 if (frent->fe_off + frent->fe_len > total || 669 (frent->fe_off + frent->fe_len == total && frent->fe_mff)) 670 goto free_ipv6_fragment; 671 } else { 672 if (frent->fe_off + frent->fe_len == total && !frent->fe_mff) 673 goto free_ipv6_fragment; 674 } 675 676 /* Find neighbors for newly inserted fragment */ 677 prev = pf_frent_previous(frag, frent); 678 if (prev == NULL) { 679 after = TAILQ_FIRST(&frag->fr_queue); 680 KASSERT(after != NULL, ("after != NULL")); 681 } else { 682 after = TAILQ_NEXT(prev, fr_next); 683 } 684 685 if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) { 686 uint16_t precut; 687 688 if (frag->fr_node->fn_af == AF_INET6) 689 goto free_fragment; 690 691 precut = prev->fe_off + prev->fe_len - frent->fe_off; 692 if (precut >= frent->fe_len) { 693 DPFPRINTF(PF_DEBUG_MISC, "new frag overlapped"); 694 goto drop_fragment; 695 } 696 DPFPRINTF(PF_DEBUG_MISC, "frag head overlap %d", precut); 697 m_adj(frent->fe_m, precut); 698 frent->fe_off += precut; 699 frent->fe_len -= precut; 700 } 701 702 for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off; 703 after = next) { 704 uint16_t aftercut; 705 706 aftercut = frent->fe_off + frent->fe_len - after->fe_off; 707 if (aftercut < after->fe_len) { 708 DPFPRINTF(PF_DEBUG_MISC, "frag tail overlap %d", 709 aftercut); 710 m_adj(after->fe_m, aftercut); 711 /* Fragment may switch queue as fe_off changes */ 712 pf_frent_remove(frag, after); 713 after->fe_off += aftercut; 714 after->fe_len -= aftercut; 715 /* Insert into correct queue */ 716 if (pf_frent_insert(frag, after, prev)) { 717 DPFPRINTF(PF_DEBUG_MISC, 718 "fragment requeue limit exceeded"); 719 m_freem(after->fe_m); 720 uma_zfree(V_pf_frent_z, after); 721 /* There is not way to recover */ 722 goto free_fragment; 723 } 724 break; 725 } 726 727 /* This fragment is completely overlapped, lose it. */ 728 DPFPRINTF(PF_DEBUG_MISC, "old frag overlapped"); 729 next = TAILQ_NEXT(after, fr_next); 730 pf_frent_remove(frag, after); 731 m_freem(after->fe_m); 732 uma_zfree(V_pf_frent_z, after); 733 } 734 735 /* If part of the queue gets too long, there is not way to recover. */ 736 if (pf_frent_insert(frag, frent, prev)) { 737 DPFPRINTF(PF_DEBUG_MISC, "fragment queue limit exceeded"); 738 goto bad_fragment; 739 } 740 741 return (frag); 742 743 free_ipv6_fragment: 744 if (frag->fr_node->fn_af == AF_INET) 745 goto bad_fragment; 746 free_fragment: 747 /* 748 * RFC 5722, Errata 3089: When reassembling an IPv6 datagram, if one 749 * or more its constituent fragments is determined to be an overlapping 750 * fragment, the entire datagram (and any constituent fragments) MUST 751 * be silently discarded. 752 */ 753 DPFPRINTF(PF_DEBUG_MISC, "flush overlapping fragments"); 754 pf_free_fragment(frag); 755 756 bad_fragment: 757 REASON_SET(reason, PFRES_FRAG); 758 drop_fragment: 759 uma_zfree(V_pf_frent_z, frent); 760 return (NULL); 761 } 762 763 static struct mbuf * 764 pf_join_fragment(struct pf_fragment *frag) 765 { 766 struct mbuf *m, *m2; 767 struct pf_frent *frent; 768 769 frent = TAILQ_FIRST(&frag->fr_queue); 770 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 771 772 m = frent->fe_m; 773 if ((frent->fe_hdrlen + frent->fe_len) < m->m_pkthdr.len) 774 m_adj(m, (frent->fe_hdrlen + frent->fe_len) - m->m_pkthdr.len); 775 uma_zfree(V_pf_frent_z, frent); 776 while ((frent = TAILQ_FIRST(&frag->fr_queue)) != NULL) { 777 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 778 779 m2 = frent->fe_m; 780 /* Strip off ip header. */ 781 m_adj(m2, frent->fe_hdrlen); 782 /* Strip off any trailing bytes. */ 783 if (frent->fe_len < m2->m_pkthdr.len) 784 m_adj(m2, frent->fe_len - m2->m_pkthdr.len); 785 786 uma_zfree(V_pf_frent_z, frent); 787 m_cat(m, m2); 788 } 789 790 /* Remove from fragment queue. */ 791 pf_free_fragment(frag); 792 793 return (m); 794 } 795 796 #ifdef INET 797 static int 798 pf_reassemble(struct mbuf **m0, u_short *reason) 799 { 800 struct mbuf *m = *m0; 801 struct ip *ip = mtod(m, struct ip *); 802 struct pf_frent *frent; 803 struct pf_fragment *frag; 804 struct m_tag *mtag; 805 struct pf_fragment_tag *ftag; 806 struct pf_frnode key; 807 uint16_t total, hdrlen; 808 uint32_t frag_id; 809 uint16_t maxlen; 810 811 /* Get an entry for the fragment queue */ 812 if ((frent = pf_create_fragment(reason)) == NULL) 813 return (PF_DROP); 814 815 frent->fe_m = m; 816 frent->fe_hdrlen = ip->ip_hl << 2; 817 frent->fe_extoff = 0; 818 frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2); 819 frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3; 820 frent->fe_mff = ntohs(ip->ip_off) & IP_MF; 821 822 pf_ip2key(ip, &key); 823 824 if ((frag = pf_fillup_fragment(&key, ip->ip_id, frent, reason)) == NULL) 825 return (PF_DROP); 826 827 /* The mbuf is part of the fragment entry, no direct free or access */ 828 m = *m0 = NULL; 829 830 if (frag->fr_holes) { 831 DPFPRINTF(PF_DEBUG_MISC, "frag %d, holes %d", 832 frag->fr_id, frag->fr_holes); 833 return (PF_PASS); /* drop because *m0 is NULL, no error */ 834 } 835 836 /* We have all the data */ 837 frent = TAILQ_FIRST(&frag->fr_queue); 838 KASSERT(frent != NULL, ("frent != NULL")); 839 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 840 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 841 hdrlen = frent->fe_hdrlen; 842 843 maxlen = frag->fr_maxlen; 844 frag_id = frag->fr_id; 845 m = *m0 = pf_join_fragment(frag); 846 frag = NULL; 847 848 if (m->m_flags & M_PKTHDR) { 849 int plen = 0; 850 for (m = *m0; m; m = m->m_next) 851 plen += m->m_len; 852 m = *m0; 853 m->m_pkthdr.len = plen; 854 } 855 856 if ((mtag = m_tag_get(PACKET_TAG_PF_REASSEMBLED, 857 sizeof(struct pf_fragment_tag), M_NOWAIT)) == NULL) { 858 REASON_SET(reason, PFRES_SHORT); 859 /* PF_DROP requires a valid mbuf *m0 in pf_test() */ 860 return (PF_DROP); 861 } 862 ftag = (struct pf_fragment_tag *)(mtag + 1); 863 ftag->ft_hdrlen = hdrlen; 864 ftag->ft_extoff = 0; 865 ftag->ft_maxlen = maxlen; 866 ftag->ft_id = frag_id; 867 m_tag_prepend(m, mtag); 868 869 ip = mtod(m, struct ip *); 870 ip->ip_sum = pf_cksum_fixup(ip->ip_sum, ip->ip_len, 871 htons(hdrlen + total), 0); 872 ip->ip_len = htons(hdrlen + total); 873 ip->ip_sum = pf_cksum_fixup(ip->ip_sum, ip->ip_off, 874 ip->ip_off & ~(IP_MF|IP_OFFMASK), 0); 875 ip->ip_off &= ~(IP_MF|IP_OFFMASK); 876 877 if (hdrlen + total > IP_MAXPACKET) { 878 DPFPRINTF(PF_DEBUG_MISC, "drop: too big: %d", total); 879 ip->ip_len = 0; 880 REASON_SET(reason, PFRES_SHORT); 881 /* PF_DROP requires a valid mbuf *m0 in pf_test() */ 882 return (PF_DROP); 883 } 884 885 DPFPRINTF(PF_DEBUG_MISC, "complete: %p(%d)", m, ntohs(ip->ip_len)); 886 return (PF_PASS); 887 } 888 #endif /* INET */ 889 890 #ifdef INET6 891 static int 892 pf_reassemble6(struct mbuf **m0, struct ip6_frag *fraghdr, 893 uint16_t hdrlen, uint16_t extoff, u_short *reason) 894 { 895 struct mbuf *m = *m0; 896 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 897 struct pf_frent *frent; 898 struct pf_fragment *frag; 899 struct pf_frnode key; 900 struct m_tag *mtag; 901 struct pf_fragment_tag *ftag; 902 int off; 903 uint32_t frag_id; 904 uint16_t total, maxlen; 905 uint8_t proto; 906 907 PF_FRAG_LOCK(); 908 909 /* Get an entry for the fragment queue. */ 910 if ((frent = pf_create_fragment(reason)) == NULL) { 911 PF_FRAG_UNLOCK(); 912 return (PF_DROP); 913 } 914 915 frent->fe_m = m; 916 frent->fe_hdrlen = hdrlen; 917 frent->fe_extoff = extoff; 918 frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen; 919 frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK); 920 frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG; 921 922 key.fn_src.v6 = ip6->ip6_src; 923 key.fn_dst.v6 = ip6->ip6_dst; 924 key.fn_af = AF_INET6; 925 /* Only the first fragment's protocol is relevant. */ 926 key.fn_proto = 0; 927 928 if ((frag = pf_fillup_fragment(&key, fraghdr->ip6f_ident, frent, reason)) == NULL) { 929 PF_FRAG_UNLOCK(); 930 return (PF_DROP); 931 } 932 933 /* The mbuf is part of the fragment entry, no direct free or access. */ 934 m = *m0 = NULL; 935 936 if (frag->fr_holes) { 937 DPFPRINTF(PF_DEBUG_MISC, "frag %d, holes %d", frag->fr_id, 938 frag->fr_holes); 939 PF_FRAG_UNLOCK(); 940 return (PF_PASS); /* Drop because *m0 is NULL, no error. */ 941 } 942 943 /* We have all the data. */ 944 frent = TAILQ_FIRST(&frag->fr_queue); 945 KASSERT(frent != NULL, ("frent != NULL")); 946 extoff = frent->fe_extoff; 947 maxlen = frag->fr_maxlen; 948 frag_id = frag->fr_id; 949 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 950 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 951 hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag); 952 953 m = *m0 = pf_join_fragment(frag); 954 frag = NULL; 955 956 PF_FRAG_UNLOCK(); 957 958 /* Take protocol from first fragment header. */ 959 m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off); 960 KASSERT(m, ("%s: short mbuf chain", __func__)); 961 proto = *(mtod(m, uint8_t *) + off); 962 m = *m0; 963 964 /* Delete frag6 header */ 965 if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0) 966 goto fail; 967 968 if (m->m_flags & M_PKTHDR) { 969 int plen = 0; 970 for (m = *m0; m; m = m->m_next) 971 plen += m->m_len; 972 m = *m0; 973 m->m_pkthdr.len = plen; 974 } 975 976 if ((mtag = m_tag_get(PACKET_TAG_PF_REASSEMBLED, 977 sizeof(struct pf_fragment_tag), M_NOWAIT)) == NULL) 978 goto fail; 979 ftag = (struct pf_fragment_tag *)(mtag + 1); 980 ftag->ft_hdrlen = hdrlen; 981 ftag->ft_extoff = extoff; 982 ftag->ft_maxlen = maxlen; 983 ftag->ft_id = frag_id; 984 m_tag_prepend(m, mtag); 985 986 ip6 = mtod(m, struct ip6_hdr *); 987 ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total); 988 if (extoff) { 989 /* Write protocol into next field of last extension header. */ 990 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt), 991 &off); 992 KASSERT(m, ("%s: short mbuf chain", __func__)); 993 *(mtod(m, char *) + off) = proto; 994 m = *m0; 995 } else 996 ip6->ip6_nxt = proto; 997 998 if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) { 999 DPFPRINTF(PF_DEBUG_MISC, "drop: too big: %d", total); 1000 ip6->ip6_plen = 0; 1001 REASON_SET(reason, PFRES_SHORT); 1002 /* PF_DROP requires a valid mbuf *m0 in pf_test6(). */ 1003 return (PF_DROP); 1004 } 1005 1006 DPFPRINTF(PF_DEBUG_MISC, "complete: %p(%d)", m, 1007 ntohs(ip6->ip6_plen)); 1008 return (PF_PASS); 1009 1010 fail: 1011 REASON_SET(reason, PFRES_MEMORY); 1012 /* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */ 1013 return (PF_DROP); 1014 } 1015 #endif /* INET6 */ 1016 1017 #ifdef INET6 1018 int 1019 pf_max_frag_size(struct mbuf *m) 1020 { 1021 struct m_tag *tag; 1022 struct pf_fragment_tag *ftag; 1023 1024 tag = m_tag_find(m, PACKET_TAG_PF_REASSEMBLED, NULL); 1025 if (tag == NULL) 1026 return (m->m_pkthdr.len); 1027 1028 ftag = (struct pf_fragment_tag *)(tag + 1); 1029 1030 return (ftag->ft_maxlen); 1031 } 1032 1033 int 1034 pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag, 1035 struct ifnet *rt, bool forward) 1036 { 1037 struct mbuf *m = *m0, *t; 1038 struct ip6_hdr *hdr; 1039 struct pf_fragment_tag *ftag = (struct pf_fragment_tag *)(mtag + 1); 1040 struct pf_pdesc pd; 1041 uint32_t frag_id; 1042 uint16_t hdrlen, extoff, maxlen; 1043 uint8_t proto; 1044 int error, action; 1045 1046 hdrlen = ftag->ft_hdrlen; 1047 extoff = ftag->ft_extoff; 1048 maxlen = ftag->ft_maxlen; 1049 frag_id = ftag->ft_id; 1050 m_tag_delete(m, mtag); 1051 mtag = NULL; 1052 ftag = NULL; 1053 1054 if (extoff) { 1055 int off; 1056 1057 /* Use protocol from next field of last extension header */ 1058 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt), 1059 &off); 1060 KASSERT((m != NULL), ("pf_refragment6: short mbuf chain")); 1061 proto = *(mtod(m, uint8_t *) + off); 1062 *(mtod(m, char *) + off) = IPPROTO_FRAGMENT; 1063 m = *m0; 1064 } else { 1065 hdr = mtod(m, struct ip6_hdr *); 1066 proto = hdr->ip6_nxt; 1067 hdr->ip6_nxt = IPPROTO_FRAGMENT; 1068 } 1069 1070 /* In case of link-local traffic we'll need a scope set. */ 1071 hdr = mtod(m, struct ip6_hdr *); 1072 1073 in6_setscope(&hdr->ip6_src, ifp, NULL); 1074 in6_setscope(&hdr->ip6_dst, ifp, NULL); 1075 1076 /* The MTU must be a multiple of 8 bytes, or we risk doing the 1077 * fragmentation wrong. */ 1078 maxlen = maxlen & ~7; 1079 1080 /* 1081 * Maxlen may be less than 8 if there was only a single 1082 * fragment. As it was fragmented before, add a fragment 1083 * header also for a single fragment. If total or maxlen 1084 * is less than 8, ip6_fragment() will return EMSGSIZE and 1085 * we drop the packet. 1086 */ 1087 error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id); 1088 m = (*m0)->m_nextpkt; 1089 (*m0)->m_nextpkt = NULL; 1090 if (error == 0) { 1091 /* The first mbuf contains the unfragmented packet. */ 1092 m_freem(*m0); 1093 *m0 = NULL; 1094 action = PF_PASS; 1095 } else { 1096 /* Drop expects an mbuf to free. */ 1097 DPFPRINTF(PF_DEBUG_MISC, "refragment error %d", error); 1098 action = PF_DROP; 1099 } 1100 for (; m; m = t) { 1101 t = m->m_nextpkt; 1102 m->m_nextpkt = NULL; 1103 m->m_flags |= M_SKIP_FIREWALL; 1104 memset(&pd, 0, sizeof(pd)); 1105 pd.pf_mtag = pf_find_mtag(m); 1106 if (error != 0) { 1107 m_freem(m); 1108 continue; 1109 } 1110 if (rt != NULL) { 1111 struct sockaddr_in6 dst; 1112 hdr = mtod(m, struct ip6_hdr *); 1113 1114 bzero(&dst, sizeof(dst)); 1115 dst.sin6_family = AF_INET6; 1116 dst.sin6_len = sizeof(dst); 1117 dst.sin6_addr = hdr->ip6_dst; 1118 1119 if (m->m_pkthdr.len <= if_getmtu(ifp)) { 1120 nd6_output_ifp(rt, rt, m, &dst, NULL); 1121 } else { 1122 in6_ifstat_inc(ifp, ifs6_in_toobig); 1123 icmp6_error(m, ICMP6_PACKET_TOO_BIG, 0, 1124 if_getmtu(ifp)); 1125 } 1126 } else if (forward) { 1127 MPASS(m->m_pkthdr.rcvif != NULL); 1128 ip6_forward(m, 0); 1129 } else { 1130 (void)ip6_output(m, NULL, NULL, 0, NULL, NULL, 1131 NULL); 1132 } 1133 } 1134 1135 return (action); 1136 } 1137 #endif /* INET6 */ 1138 1139 #ifdef INET 1140 int 1141 pf_normalize_ip(u_short *reason, struct pf_pdesc *pd) 1142 { 1143 struct pf_krule *r; 1144 struct ip *h = mtod(pd->m, struct ip *); 1145 int mff = (ntohs(h->ip_off) & IP_MF); 1146 int hlen = h->ip_hl << 2; 1147 u_int16_t fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3; 1148 u_int16_t max; 1149 int ip_len; 1150 int tag = -1; 1151 int verdict; 1152 bool scrub_compat; 1153 1154 PF_RULES_RASSERT(); 1155 1156 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1157 /* 1158 * Check if there are any scrub rules, matching or not. 1159 * Lack of scrub rules means: 1160 * - enforced packet normalization operation just like in OpenBSD 1161 * - fragment reassembly depends on V_pf_status.reass 1162 * With scrub rules: 1163 * - packet normalization is performed if there is a matching scrub rule 1164 * - fragment reassembly is performed if the matching rule has no 1165 * PFRULE_FRAGMENT_NOREASS flag 1166 */ 1167 scrub_compat = (r != NULL); 1168 while (r != NULL) { 1169 pf_counter_u64_add(&r->evaluations, 1); 1170 if (pfi_kkif_match(r->kif, pd->kif) == r->ifnot) 1171 r = r->skip[PF_SKIP_IFP]; 1172 else if (r->direction && r->direction != pd->dir) 1173 r = r->skip[PF_SKIP_DIR]; 1174 else if (r->af && r->af != AF_INET) 1175 r = r->skip[PF_SKIP_AF]; 1176 else if (r->proto && r->proto != h->ip_p) 1177 r = r->skip[PF_SKIP_PROTO]; 1178 else if (PF_MISMATCHAW(&r->src.addr, 1179 (struct pf_addr *)&h->ip_src.s_addr, AF_INET, 1180 r->src.neg, pd->kif, M_GETFIB(pd->m))) 1181 r = r->skip[PF_SKIP_SRC_ADDR]; 1182 else if (PF_MISMATCHAW(&r->dst.addr, 1183 (struct pf_addr *)&h->ip_dst.s_addr, AF_INET, 1184 r->dst.neg, NULL, M_GETFIB(pd->m))) 1185 r = r->skip[PF_SKIP_DST_ADDR]; 1186 else if (r->match_tag && !pf_match_tag(pd->m, r, &tag, 1187 pd->pf_mtag ? pd->pf_mtag->tag : 0)) 1188 r = TAILQ_NEXT(r, entries); 1189 else 1190 break; 1191 } 1192 1193 if (scrub_compat) { 1194 /* With scrub rules present IPv4 normalization happens only 1195 * if one of rules has matched and it's not a "no scrub" rule */ 1196 if (r == NULL || r->action == PF_NOSCRUB) 1197 return (PF_PASS); 1198 1199 pf_counter_u64_critical_enter(); 1200 pf_counter_u64_add_protected(&r->packets[pd->dir == PF_OUT], 1); 1201 pf_counter_u64_add_protected(&r->bytes[pd->dir == PF_OUT], pd->tot_len); 1202 pf_counter_u64_critical_exit(); 1203 pf_rule_to_actions(r, &pd->act); 1204 } 1205 1206 /* Check for illegal packets */ 1207 if (hlen < (int)sizeof(struct ip)) { 1208 REASON_SET(reason, PFRES_NORM); 1209 goto drop; 1210 } 1211 1212 if (hlen > ntohs(h->ip_len)) { 1213 REASON_SET(reason, PFRES_NORM); 1214 goto drop; 1215 } 1216 1217 /* Clear IP_DF if the rule uses the no-df option or we're in no-df mode */ 1218 if (((!scrub_compat && V_pf_status.reass & PF_REASS_NODF) || 1219 (r != NULL && r->rule_flag & PFRULE_NODF)) && 1220 (h->ip_off & htons(IP_DF)) 1221 ) { 1222 u_int16_t ip_off = h->ip_off; 1223 1224 h->ip_off &= htons(~IP_DF); 1225 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1226 } 1227 1228 /* We will need other tests here */ 1229 if (!fragoff && !mff) 1230 goto no_fragment; 1231 1232 /* We're dealing with a fragment now. Don't allow fragments 1233 * with IP_DF to enter the cache. If the flag was cleared by 1234 * no-df above, fine. Otherwise drop it. 1235 */ 1236 if (h->ip_off & htons(IP_DF)) { 1237 DPFPRINTF(PF_DEBUG_MISC, "IP_DF"); 1238 goto bad; 1239 } 1240 1241 ip_len = ntohs(h->ip_len) - hlen; 1242 1243 /* All fragments are 8 byte aligned */ 1244 if (mff && (ip_len & 0x7)) { 1245 DPFPRINTF(PF_DEBUG_MISC, "mff and %d", ip_len); 1246 goto bad; 1247 } 1248 1249 /* Respect maximum length */ 1250 if (fragoff + ip_len > IP_MAXPACKET) { 1251 DPFPRINTF(PF_DEBUG_MISC, "max packet %d", fragoff + ip_len); 1252 goto bad; 1253 } 1254 1255 if ((!scrub_compat && V_pf_status.reass) || 1256 (r != NULL && !(r->rule_flag & PFRULE_FRAGMENT_NOREASS)) 1257 ) { 1258 max = fragoff + ip_len; 1259 1260 /* Fully buffer all of the fragments 1261 * Might return a completely reassembled mbuf, or NULL */ 1262 PF_FRAG_LOCK(); 1263 DPFPRINTF(PF_DEBUG_MISC, "reass frag %d @ %d-%d", 1264 h->ip_id, fragoff, max); 1265 verdict = pf_reassemble(&pd->m, reason); 1266 PF_FRAG_UNLOCK(); 1267 1268 if (verdict != PF_PASS) 1269 return (PF_DROP); 1270 1271 if (pd->m == NULL) 1272 return (PF_DROP); 1273 1274 h = mtod(pd->m, struct ip *); 1275 pd->tot_len = htons(h->ip_len); 1276 1277 no_fragment: 1278 /* At this point, only IP_DF is allowed in ip_off */ 1279 if (h->ip_off & ~htons(IP_DF)) { 1280 u_int16_t ip_off = h->ip_off; 1281 1282 h->ip_off &= htons(IP_DF); 1283 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1284 } 1285 } 1286 1287 return (PF_PASS); 1288 1289 bad: 1290 DPFPRINTF(PF_DEBUG_MISC, "dropping bad fragment"); 1291 REASON_SET(reason, PFRES_FRAG); 1292 drop: 1293 if (r != NULL && r->log) 1294 PFLOG_PACKET(PF_DROP, *reason, r, NULL, NULL, pd, 1, NULL); 1295 1296 return (PF_DROP); 1297 } 1298 #endif 1299 1300 #ifdef INET6 1301 int 1302 pf_normalize_ip6(int off, u_short *reason, 1303 struct pf_pdesc *pd) 1304 { 1305 struct pf_krule *r; 1306 struct ip6_hdr *h; 1307 struct ip6_frag frag; 1308 bool scrub_compat; 1309 1310 PF_RULES_RASSERT(); 1311 1312 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1313 /* 1314 * Check if there are any scrub rules, matching or not. 1315 * Lack of scrub rules means: 1316 * - enforced packet normalization operation just like in OpenBSD 1317 * With scrub rules: 1318 * - packet normalization is performed if there is a matching scrub rule 1319 * XXX: Fragment reassembly always performed for IPv6! 1320 */ 1321 scrub_compat = (r != NULL); 1322 while (r != NULL) { 1323 pf_counter_u64_add(&r->evaluations, 1); 1324 if (pfi_kkif_match(r->kif, pd->kif) == r->ifnot) 1325 r = r->skip[PF_SKIP_IFP]; 1326 else if (r->direction && r->direction != pd->dir) 1327 r = r->skip[PF_SKIP_DIR]; 1328 else if (r->af && r->af != AF_INET6) 1329 r = r->skip[PF_SKIP_AF]; 1330 else if (r->proto && r->proto != pd->proto) 1331 r = r->skip[PF_SKIP_PROTO]; 1332 else if (PF_MISMATCHAW(&r->src.addr, 1333 (struct pf_addr *)&pd->src, AF_INET6, 1334 r->src.neg, pd->kif, M_GETFIB(pd->m))) 1335 r = r->skip[PF_SKIP_SRC_ADDR]; 1336 else if (PF_MISMATCHAW(&r->dst.addr, 1337 (struct pf_addr *)&pd->dst, AF_INET6, 1338 r->dst.neg, NULL, M_GETFIB(pd->m))) 1339 r = r->skip[PF_SKIP_DST_ADDR]; 1340 else 1341 break; 1342 } 1343 1344 if (scrub_compat) { 1345 /* With scrub rules present IPv6 normalization happens only 1346 * if one of rules has matched and it's not a "no scrub" rule */ 1347 if (r == NULL || r->action == PF_NOSCRUB) 1348 return (PF_PASS); 1349 1350 pf_counter_u64_critical_enter(); 1351 pf_counter_u64_add_protected(&r->packets[pd->dir == PF_OUT], 1); 1352 pf_counter_u64_add_protected(&r->bytes[pd->dir == PF_OUT], pd->tot_len); 1353 pf_counter_u64_critical_exit(); 1354 pf_rule_to_actions(r, &pd->act); 1355 } 1356 1357 if (!pf_pull_hdr(pd->m, off, &frag, sizeof(frag), NULL, reason, AF_INET6)) 1358 return (PF_DROP); 1359 1360 /* Offset now points to data portion. */ 1361 off += sizeof(frag); 1362 1363 if (pd->virtual_proto == PF_VPROTO_FRAGMENT) { 1364 /* Returns PF_DROP or *m0 is NULL or completely reassembled 1365 * mbuf. */ 1366 if (pf_reassemble6(&pd->m, &frag, off, pd->extoff, reason) != PF_PASS) 1367 return (PF_DROP); 1368 if (pd->m == NULL) 1369 return (PF_DROP); 1370 h = mtod(pd->m, struct ip6_hdr *); 1371 pd->tot_len = ntohs(h->ip6_plen) + sizeof(struct ip6_hdr); 1372 } 1373 1374 return (PF_PASS); 1375 } 1376 #endif /* INET6 */ 1377 1378 int 1379 pf_normalize_tcp(struct pf_pdesc *pd) 1380 { 1381 struct pf_krule *r, *rm = NULL; 1382 struct tcphdr *th = &pd->hdr.tcp; 1383 int rewrite = 0; 1384 u_short reason; 1385 u_int16_t flags; 1386 sa_family_t af = pd->af; 1387 int srs; 1388 1389 PF_RULES_RASSERT(); 1390 1391 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1392 /* Check if there any scrub rules. Lack of scrub rules means enforced 1393 * packet normalization operation just like in OpenBSD. */ 1394 srs = (r != NULL); 1395 while (r != NULL) { 1396 pf_counter_u64_add(&r->evaluations, 1); 1397 if (pfi_kkif_match(r->kif, pd->kif) == r->ifnot) 1398 r = r->skip[PF_SKIP_IFP]; 1399 else if (r->direction && r->direction != pd->dir) 1400 r = r->skip[PF_SKIP_DIR]; 1401 else if (r->af && r->af != af) 1402 r = r->skip[PF_SKIP_AF]; 1403 else if (r->proto && r->proto != pd->proto) 1404 r = r->skip[PF_SKIP_PROTO]; 1405 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, 1406 r->src.neg, pd->kif, M_GETFIB(pd->m))) 1407 r = r->skip[PF_SKIP_SRC_ADDR]; 1408 else if (r->src.port_op && !pf_match_port(r->src.port_op, 1409 r->src.port[0], r->src.port[1], th->th_sport)) 1410 r = r->skip[PF_SKIP_SRC_PORT]; 1411 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, 1412 r->dst.neg, NULL, M_GETFIB(pd->m))) 1413 r = r->skip[PF_SKIP_DST_ADDR]; 1414 else if (r->dst.port_op && !pf_match_port(r->dst.port_op, 1415 r->dst.port[0], r->dst.port[1], th->th_dport)) 1416 r = r->skip[PF_SKIP_DST_PORT]; 1417 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match( 1418 pf_osfp_fingerprint(pd, th), 1419 r->os_fingerprint)) 1420 r = TAILQ_NEXT(r, entries); 1421 else { 1422 rm = r; 1423 break; 1424 } 1425 } 1426 1427 if (srs) { 1428 /* With scrub rules present TCP normalization happens only 1429 * if one of rules has matched and it's not a "no scrub" rule */ 1430 if (rm == NULL || rm->action == PF_NOSCRUB) 1431 return (PF_PASS); 1432 1433 pf_counter_u64_critical_enter(); 1434 pf_counter_u64_add_protected(&r->packets[pd->dir == PF_OUT], 1); 1435 pf_counter_u64_add_protected(&r->bytes[pd->dir == PF_OUT], pd->tot_len); 1436 pf_counter_u64_critical_exit(); 1437 pf_rule_to_actions(rm, &pd->act); 1438 } 1439 1440 if (rm && rm->rule_flag & PFRULE_REASSEMBLE_TCP) 1441 pd->flags |= PFDESC_TCP_NORM; 1442 1443 flags = tcp_get_flags(th); 1444 if (flags & TH_SYN) { 1445 /* Illegal packet */ 1446 if (flags & TH_RST) 1447 goto tcp_drop; 1448 1449 if (flags & TH_FIN) 1450 goto tcp_drop; 1451 } else { 1452 /* Illegal packet */ 1453 if (!(flags & (TH_ACK|TH_RST))) 1454 goto tcp_drop; 1455 } 1456 1457 if (!(flags & TH_ACK)) { 1458 /* These flags are only valid if ACK is set */ 1459 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG)) 1460 goto tcp_drop; 1461 } 1462 1463 /* Check for illegal header length */ 1464 if (th->th_off < (sizeof(struct tcphdr) >> 2)) 1465 goto tcp_drop; 1466 1467 /* If flags changed, or reserved data set, then adjust */ 1468 if (flags != tcp_get_flags(th) || 1469 (tcp_get_flags(th) & (TH_RES1|TH_RES2|TH_RES2)) != 0) { 1470 u_int16_t ov, nv; 1471 1472 ov = *(u_int16_t *)(&th->th_ack + 1); 1473 flags &= ~(TH_RES1 | TH_RES2 | TH_RES3); 1474 tcp_set_flags(th, flags); 1475 nv = *(u_int16_t *)(&th->th_ack + 1); 1476 1477 th->th_sum = pf_proto_cksum_fixup(pd->m, th->th_sum, ov, nv, 0); 1478 rewrite = 1; 1479 } 1480 1481 /* Remove urgent pointer, if TH_URG is not set */ 1482 if (!(flags & TH_URG) && th->th_urp) { 1483 th->th_sum = pf_proto_cksum_fixup(pd->m, th->th_sum, th->th_urp, 1484 0, 0); 1485 th->th_urp = 0; 1486 rewrite = 1; 1487 } 1488 1489 /* copy back packet headers if we sanitized */ 1490 if (rewrite) 1491 m_copyback(pd->m, pd->off, sizeof(*th), (caddr_t)th); 1492 1493 return (PF_PASS); 1494 1495 tcp_drop: 1496 REASON_SET(&reason, PFRES_NORM); 1497 if (rm != NULL && r->log) 1498 PFLOG_PACKET(PF_DROP, reason, r, NULL, NULL, pd, 1, NULL); 1499 return (PF_DROP); 1500 } 1501 1502 int 1503 pf_normalize_tcp_init(struct pf_pdesc *pd, struct tcphdr *th, 1504 struct pf_state_peer *src) 1505 { 1506 u_int32_t tsval, tsecr; 1507 int olen; 1508 uint8_t opts[MAX_TCPOPTLEN], *opt; 1509 1510 KASSERT((src->scrub == NULL), 1511 ("pf_normalize_tcp_init: src->scrub != NULL")); 1512 1513 src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT); 1514 if (src->scrub == NULL) 1515 return (1); 1516 1517 switch (pd->af) { 1518 #ifdef INET 1519 case AF_INET: { 1520 struct ip *h = mtod(pd->m, struct ip *); 1521 src->scrub->pfss_ttl = h->ip_ttl; 1522 break; 1523 } 1524 #endif /* INET */ 1525 #ifdef INET6 1526 case AF_INET6: { 1527 struct ip6_hdr *h = mtod(pd->m, struct ip6_hdr *); 1528 src->scrub->pfss_ttl = h->ip6_hlim; 1529 break; 1530 } 1531 #endif /* INET6 */ 1532 default: 1533 unhandled_af(pd->af); 1534 } 1535 1536 /* 1537 * All normalizations below are only begun if we see the start of 1538 * the connections. They must all set an enabled bit in pfss_flags 1539 */ 1540 if ((tcp_get_flags(th) & TH_SYN) == 0) 1541 return (0); 1542 1543 olen = (th->th_off << 2) - sizeof(*th); 1544 if (olen < TCPOLEN_TIMESTAMP || !pf_pull_hdr(pd->m, 1545 pd->off + sizeof(*th), opts, olen, NULL, NULL, pd->af)) 1546 return (0); 1547 1548 opt = opts; 1549 while ((opt = pf_find_tcpopt(opt, opts, olen, 1550 TCPOPT_TIMESTAMP, TCPOLEN_TIMESTAMP)) != NULL) { 1551 src->scrub->pfss_flags |= PFSS_TIMESTAMP; 1552 src->scrub->pfss_ts_mod = arc4random(); 1553 /* note PFSS_PAWS not set yet */ 1554 memcpy(&tsval, &opt[2], sizeof(u_int32_t)); 1555 memcpy(&tsecr, &opt[6], sizeof(u_int32_t)); 1556 src->scrub->pfss_tsval0 = ntohl(tsval); 1557 src->scrub->pfss_tsval = ntohl(tsval); 1558 src->scrub->pfss_tsecr = ntohl(tsecr); 1559 getmicrouptime(&src->scrub->pfss_last); 1560 1561 opt += opt[1]; 1562 } 1563 1564 return (0); 1565 } 1566 1567 void 1568 pf_normalize_tcp_cleanup(struct pf_kstate *state) 1569 { 1570 /* XXX Note: this also cleans up SCTP. */ 1571 uma_zfree(V_pf_state_scrub_z, state->src.scrub); 1572 uma_zfree(V_pf_state_scrub_z, state->dst.scrub); 1573 1574 /* Someday... flush the TCP segment reassembly descriptors. */ 1575 } 1576 int 1577 pf_normalize_sctp_init(struct pf_pdesc *pd, struct pf_state_peer *src, 1578 struct pf_state_peer *dst) 1579 { 1580 src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT); 1581 if (src->scrub == NULL) 1582 return (1); 1583 1584 dst->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT); 1585 if (dst->scrub == NULL) { 1586 uma_zfree(V_pf_state_scrub_z, src); 1587 return (1); 1588 } 1589 1590 dst->scrub->pfss_v_tag = pd->sctp_initiate_tag; 1591 1592 return (0); 1593 } 1594 1595 int 1596 pf_normalize_tcp_stateful(struct pf_pdesc *pd, 1597 u_short *reason, struct tcphdr *th, struct pf_kstate *state, 1598 struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback) 1599 { 1600 struct timeval uptime; 1601 u_int tsval_from_last; 1602 uint32_t tsval, tsecr; 1603 int copyback = 0; 1604 int got_ts = 0; 1605 int olen; 1606 uint8_t opts[MAX_TCPOPTLEN], *opt; 1607 1608 KASSERT((src->scrub || dst->scrub), 1609 ("%s: src->scrub && dst->scrub!", __func__)); 1610 1611 /* 1612 * Enforce the minimum TTL seen for this connection. Negate a common 1613 * technique to evade an intrusion detection system and confuse 1614 * firewall state code. 1615 */ 1616 switch (pd->af) { 1617 #ifdef INET 1618 case AF_INET: { 1619 if (src->scrub) { 1620 struct ip *h = mtod(pd->m, struct ip *); 1621 if (h->ip_ttl > src->scrub->pfss_ttl) 1622 src->scrub->pfss_ttl = h->ip_ttl; 1623 h->ip_ttl = src->scrub->pfss_ttl; 1624 } 1625 break; 1626 } 1627 #endif /* INET */ 1628 #ifdef INET6 1629 case AF_INET6: { 1630 if (src->scrub) { 1631 struct ip6_hdr *h = mtod(pd->m, struct ip6_hdr *); 1632 if (h->ip6_hlim > src->scrub->pfss_ttl) 1633 src->scrub->pfss_ttl = h->ip6_hlim; 1634 h->ip6_hlim = src->scrub->pfss_ttl; 1635 } 1636 break; 1637 } 1638 #endif /* INET6 */ 1639 default: 1640 unhandled_af(pd->af); 1641 } 1642 1643 olen = (th->th_off << 2) - sizeof(*th); 1644 1645 if (olen >= TCPOLEN_TIMESTAMP && 1646 ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) || 1647 (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) && 1648 pf_pull_hdr(pd->m, pd->off + sizeof(*th), opts, olen, NULL, NULL, pd->af)) { 1649 /* Modulate the timestamps. Can be used for NAT detection, OS 1650 * uptime determination or reboot detection. 1651 */ 1652 opt = opts; 1653 while ((opt = pf_find_tcpopt(opt, opts, olen, 1654 TCPOPT_TIMESTAMP, TCPOLEN_TIMESTAMP)) != NULL) { 1655 uint8_t *ts = opt + 2; 1656 uint8_t *tsr = opt + 6; 1657 1658 if (got_ts) { 1659 /* Huh? Multiple timestamps!? */ 1660 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1661 printf("pf: %s: multiple TS??", __func__); 1662 pf_print_state(state); 1663 printf("\n"); 1664 } 1665 REASON_SET(reason, PFRES_TS); 1666 return (PF_DROP); 1667 } 1668 1669 memcpy(&tsval, ts, sizeof(u_int32_t)); 1670 memcpy(&tsecr, tsr, sizeof(u_int32_t)); 1671 1672 /* modulate TS */ 1673 if (tsval && src->scrub && 1674 (src->scrub->pfss_flags & PFSS_TIMESTAMP)) { 1675 /* tsval used further on */ 1676 tsval = ntohl(tsval); 1677 pf_patch_32(pd, 1678 ts, htonl(tsval + src->scrub->pfss_ts_mod), 1679 PF_ALGNMNT(ts - opts)); 1680 copyback = 1; 1681 } 1682 1683 /* modulate TS reply if any (!0) */ 1684 if (tsecr && dst->scrub && 1685 (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) { 1686 /* tsecr used further on */ 1687 tsecr = ntohl(tsecr) - dst->scrub->pfss_ts_mod; 1688 pf_patch_32(pd, tsr, htonl(tsecr), 1689 PF_ALGNMNT(tsr - opts)); 1690 copyback = 1; 1691 } 1692 1693 got_ts = 1; 1694 opt += opt[1]; 1695 } 1696 1697 if (copyback) { 1698 /* Copyback the options, caller copys back header */ 1699 *writeback = 1; 1700 m_copyback(pd->m, pd->off + sizeof(*th), olen, opts); 1701 } 1702 } 1703 1704 /* 1705 * Must invalidate PAWS checks on connections idle for too long. 1706 * The fastest allowed timestamp clock is 1ms. That turns out to 1707 * be about 24 days before it wraps. XXX Right now our lowerbound 1708 * TS echo check only works for the first 12 days of a connection 1709 * when the TS has exhausted half its 32bit space 1710 */ 1711 #define TS_MAX_IDLE (24*24*60*60) 1712 #define TS_MAX_CONN (12*24*60*60) /* XXX remove when better tsecr check */ 1713 1714 getmicrouptime(&uptime); 1715 if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) && 1716 (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE || 1717 time_uptime - (state->creation / 1000) > TS_MAX_CONN)) { 1718 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1719 DPFPRINTF(PF_DEBUG_MISC, "src idled out of PAWS"); 1720 pf_print_state(state); 1721 printf("\n"); 1722 } 1723 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS) 1724 | PFSS_PAWS_IDLED; 1725 } 1726 if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) && 1727 uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) { 1728 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1729 DPFPRINTF(PF_DEBUG_MISC, "dst idled out of PAWS"); 1730 pf_print_state(state); 1731 printf("\n"); 1732 } 1733 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS) 1734 | PFSS_PAWS_IDLED; 1735 } 1736 1737 if (got_ts && src->scrub && dst->scrub && 1738 (src->scrub->pfss_flags & PFSS_PAWS) && 1739 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1740 /* Validate that the timestamps are "in-window". 1741 * RFC1323 describes TCP Timestamp options that allow 1742 * measurement of RTT (round trip time) and PAWS 1743 * (protection against wrapped sequence numbers). PAWS 1744 * gives us a set of rules for rejecting packets on 1745 * long fat pipes (packets that were somehow delayed 1746 * in transit longer than the time it took to send the 1747 * full TCP sequence space of 4Gb). We can use these 1748 * rules and infer a few others that will let us treat 1749 * the 32bit timestamp and the 32bit echoed timestamp 1750 * as sequence numbers to prevent a blind attacker from 1751 * inserting packets into a connection. 1752 * 1753 * RFC1323 tells us: 1754 * - The timestamp on this packet must be greater than 1755 * or equal to the last value echoed by the other 1756 * endpoint. The RFC says those will be discarded 1757 * since it is a dup that has already been acked. 1758 * This gives us a lowerbound on the timestamp. 1759 * timestamp >= other last echoed timestamp 1760 * - The timestamp will be less than or equal to 1761 * the last timestamp plus the time between the 1762 * last packet and now. The RFC defines the max 1763 * clock rate as 1ms. We will allow clocks to be 1764 * up to 10% fast and will allow a total difference 1765 * or 30 seconds due to a route change. And this 1766 * gives us an upperbound on the timestamp. 1767 * timestamp <= last timestamp + max ticks 1768 * We have to be careful here. Windows will send an 1769 * initial timestamp of zero and then initialize it 1770 * to a random value after the 3whs; presumably to 1771 * avoid a DoS by having to call an expensive RNG 1772 * during a SYN flood. Proof MS has at least one 1773 * good security geek. 1774 * 1775 * - The TCP timestamp option must also echo the other 1776 * endpoints timestamp. The timestamp echoed is the 1777 * one carried on the earliest unacknowledged segment 1778 * on the left edge of the sequence window. The RFC 1779 * states that the host will reject any echoed 1780 * timestamps that were larger than any ever sent. 1781 * This gives us an upperbound on the TS echo. 1782 * tescr <= largest_tsval 1783 * - The lowerbound on the TS echo is a little more 1784 * tricky to determine. The other endpoint's echoed 1785 * values will not decrease. But there may be 1786 * network conditions that re-order packets and 1787 * cause our view of them to decrease. For now the 1788 * only lowerbound we can safely determine is that 1789 * the TS echo will never be less than the original 1790 * TS. XXX There is probably a better lowerbound. 1791 * Remove TS_MAX_CONN with better lowerbound check. 1792 * tescr >= other original TS 1793 * 1794 * It is also important to note that the fastest 1795 * timestamp clock of 1ms will wrap its 32bit space in 1796 * 24 days. So we just disable TS checking after 24 1797 * days of idle time. We actually must use a 12d 1798 * connection limit until we can come up with a better 1799 * lowerbound to the TS echo check. 1800 */ 1801 struct timeval delta_ts; 1802 int ts_fudge; 1803 1804 /* 1805 * PFTM_TS_DIFF is how many seconds of leeway to allow 1806 * a host's timestamp. This can happen if the previous 1807 * packet got delayed in transit for much longer than 1808 * this packet. 1809 */ 1810 if ((ts_fudge = state->rule->timeout[PFTM_TS_DIFF]) == 0) 1811 ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF]; 1812 1813 /* Calculate max ticks since the last timestamp */ 1814 #define TS_MAXFREQ 1100 /* RFC max TS freq of 1Khz + 10% skew */ 1815 #define TS_MICROSECS 1000000 /* microseconds per second */ 1816 delta_ts = uptime; 1817 timevalsub(&delta_ts, &src->scrub->pfss_last); 1818 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ; 1819 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ); 1820 1821 if ((src->state >= TCPS_ESTABLISHED && 1822 dst->state >= TCPS_ESTABLISHED) && 1823 (SEQ_LT(tsval, dst->scrub->pfss_tsecr) || 1824 SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) || 1825 (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) || 1826 SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) { 1827 /* Bad RFC1323 implementation or an insertion attack. 1828 * 1829 * - Solaris 2.6 and 2.7 are known to send another ACK 1830 * after the FIN,FIN|ACK,ACK closing that carries 1831 * an old timestamp. 1832 */ 1833 1834 DPFPRINTF(PF_DEBUG_MISC, "Timestamp failed %c%c%c%c", 1835 SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ', 1836 SEQ_GT(tsval, src->scrub->pfss_tsval + 1837 tsval_from_last) ? '1' : ' ', 1838 SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ', 1839 SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' '); 1840 DPFPRINTF(PF_DEBUG_MISC, " tsval: %u tsecr: %u +ticks: " 1841 "%u idle: %jus %lums", 1842 tsval, tsecr, tsval_from_last, 1843 (uintmax_t)delta_ts.tv_sec, 1844 delta_ts.tv_usec / 1000); 1845 DPFPRINTF(PF_DEBUG_MISC, " src->tsval: %u tsecr: %u", 1846 src->scrub->pfss_tsval, src->scrub->pfss_tsecr); 1847 DPFPRINTF(PF_DEBUG_MISC, " dst->tsval: %u tsecr: %u " 1848 "tsval0: %u", dst->scrub->pfss_tsval, 1849 dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0); 1850 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1851 pf_print_state(state); 1852 pf_print_flags(tcp_get_flags(th)); 1853 printf("\n"); 1854 } 1855 REASON_SET(reason, PFRES_TS); 1856 return (PF_DROP); 1857 } 1858 1859 /* XXX I'd really like to require tsecr but it's optional */ 1860 1861 } else if (!got_ts && (tcp_get_flags(th) & TH_RST) == 0 && 1862 ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED) 1863 || pd->p_len > 0 || (tcp_get_flags(th) & TH_SYN)) && 1864 src->scrub && dst->scrub && 1865 (src->scrub->pfss_flags & PFSS_PAWS) && 1866 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1867 /* Didn't send a timestamp. Timestamps aren't really useful 1868 * when: 1869 * - connection opening or closing (often not even sent). 1870 * but we must not let an attacker to put a FIN on a 1871 * data packet to sneak it through our ESTABLISHED check. 1872 * - on a TCP reset. RFC suggests not even looking at TS. 1873 * - on an empty ACK. The TS will not be echoed so it will 1874 * probably not help keep the RTT calculation in sync and 1875 * there isn't as much danger when the sequence numbers 1876 * got wrapped. So some stacks don't include TS on empty 1877 * ACKs :-( 1878 * 1879 * To minimize the disruption to mostly RFC1323 conformant 1880 * stacks, we will only require timestamps on data packets. 1881 * 1882 * And what do ya know, we cannot require timestamps on data 1883 * packets. There appear to be devices that do legitimate 1884 * TCP connection hijacking. There are HTTP devices that allow 1885 * a 3whs (with timestamps) and then buffer the HTTP request. 1886 * If the intermediate device has the HTTP response cache, it 1887 * will spoof the response but not bother timestamping its 1888 * packets. So we can look for the presence of a timestamp in 1889 * the first data packet and if there, require it in all future 1890 * packets. 1891 */ 1892 1893 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) { 1894 /* 1895 * Hey! Someone tried to sneak a packet in. Or the 1896 * stack changed its RFC1323 behavior?!?! 1897 */ 1898 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1899 DPFPRINTF(PF_DEBUG_MISC, "Did not receive expected " 1900 "RFC1323 timestamp"); 1901 pf_print_state(state); 1902 pf_print_flags(tcp_get_flags(th)); 1903 printf("\n"); 1904 } 1905 REASON_SET(reason, PFRES_TS); 1906 return (PF_DROP); 1907 } 1908 } 1909 1910 /* 1911 * We will note if a host sends his data packets with or without 1912 * timestamps. And require all data packets to contain a timestamp 1913 * if the first does. PAWS implicitly requires that all data packets be 1914 * timestamped. But I think there are middle-man devices that hijack 1915 * TCP streams immediately after the 3whs and don't timestamp their 1916 * packets (seen in a WWW accelerator or cache). 1917 */ 1918 if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags & 1919 (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) { 1920 if (got_ts) 1921 src->scrub->pfss_flags |= PFSS_DATA_TS; 1922 else { 1923 src->scrub->pfss_flags |= PFSS_DATA_NOTS; 1924 if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub && 1925 (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) { 1926 /* Don't warn if other host rejected RFC1323 */ 1927 DPFPRINTF(PF_DEBUG_MISC, "Broken RFC1323 stack did " 1928 "not timestamp data packet. Disabled PAWS " 1929 "security."); 1930 pf_print_state(state); 1931 pf_print_flags(tcp_get_flags(th)); 1932 printf("\n"); 1933 } 1934 } 1935 } 1936 1937 /* 1938 * Update PAWS values 1939 */ 1940 if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags & 1941 (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) { 1942 getmicrouptime(&src->scrub->pfss_last); 1943 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) || 1944 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 1945 src->scrub->pfss_tsval = tsval; 1946 1947 if (tsecr) { 1948 if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) || 1949 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 1950 src->scrub->pfss_tsecr = tsecr; 1951 1952 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 && 1953 (SEQ_LT(tsval, src->scrub->pfss_tsval0) || 1954 src->scrub->pfss_tsval0 == 0)) { 1955 /* tsval0 MUST be the lowest timestamp */ 1956 src->scrub->pfss_tsval0 = tsval; 1957 } 1958 1959 /* Only fully initialized after a TS gets echoed */ 1960 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0) 1961 src->scrub->pfss_flags |= PFSS_PAWS; 1962 } 1963 } 1964 1965 /* I have a dream.... TCP segment reassembly.... */ 1966 return (0); 1967 } 1968 1969 int 1970 pf_normalize_mss(struct pf_pdesc *pd) 1971 { 1972 int olen, optsoff; 1973 uint8_t opts[MAX_TCPOPTLEN], *opt; 1974 1975 olen = (pd->hdr.tcp.th_off << 2) - sizeof(struct tcphdr); 1976 optsoff = pd->off + sizeof(struct tcphdr); 1977 if (olen < TCPOLEN_MAXSEG || 1978 !pf_pull_hdr(pd->m, optsoff, opts, olen, NULL, NULL, pd->af)) 1979 return (0); 1980 1981 opt = opts; 1982 while ((opt = pf_find_tcpopt(opt, opts, olen, 1983 TCPOPT_MAXSEG, TCPOLEN_MAXSEG)) != NULL) { 1984 uint16_t mss; 1985 uint8_t *mssp = opt + 2; 1986 memcpy(&mss, mssp, sizeof(mss)); 1987 if (ntohs(mss) > pd->act.max_mss) { 1988 size_t mssoffopts = mssp - opts; 1989 pf_patch_16(pd, &mss, 1990 htons(pd->act.max_mss), PF_ALGNMNT(mssoffopts)); 1991 m_copyback(pd->m, optsoff + mssoffopts, 1992 sizeof(mss), (caddr_t)&mss); 1993 m_copyback(pd->m, pd->off, 1994 sizeof(struct tcphdr), (caddr_t)&pd->hdr.tcp); 1995 } 1996 1997 opt += opt[1]; 1998 } 1999 2000 return (0); 2001 } 2002 2003 int 2004 pf_scan_sctp(struct pf_pdesc *pd) 2005 { 2006 struct sctp_chunkhdr ch = { }; 2007 int chunk_off = sizeof(struct sctphdr); 2008 int chunk_start; 2009 int ret; 2010 2011 while (pd->off + chunk_off < pd->tot_len) { 2012 if (!pf_pull_hdr(pd->m, pd->off + chunk_off, &ch, sizeof(ch), NULL, 2013 NULL, pd->af)) 2014 return (PF_DROP); 2015 2016 /* Length includes the header, this must be at least 4. */ 2017 if (ntohs(ch.chunk_length) < 4) 2018 return (PF_DROP); 2019 2020 chunk_start = chunk_off; 2021 chunk_off += roundup(ntohs(ch.chunk_length), 4); 2022 2023 switch (ch.chunk_type) { 2024 case SCTP_INITIATION: 2025 case SCTP_INITIATION_ACK: { 2026 struct sctp_init_chunk init; 2027 2028 if (!pf_pull_hdr(pd->m, pd->off + chunk_start, &init, 2029 sizeof(init), NULL, NULL, pd->af)) 2030 return (PF_DROP); 2031 2032 /* 2033 * RFC 9620, Section 3.3.2, "The Initiate Tag is allowed to have 2034 * any value except 0." 2035 */ 2036 if (init.init.initiate_tag == 0) 2037 return (PF_DROP); 2038 if (init.init.num_inbound_streams == 0) 2039 return (PF_DROP); 2040 if (init.init.num_outbound_streams == 0) 2041 return (PF_DROP); 2042 if (ntohl(init.init.a_rwnd) < SCTP_MIN_RWND) 2043 return (PF_DROP); 2044 2045 /* 2046 * RFC 9260, Section 3.1, INIT chunks MUST have zero 2047 * verification tag. 2048 */ 2049 if (ch.chunk_type == SCTP_INITIATION && 2050 pd->hdr.sctp.v_tag != 0) 2051 return (PF_DROP); 2052 2053 pd->sctp_initiate_tag = init.init.initiate_tag; 2054 2055 if (ch.chunk_type == SCTP_INITIATION) 2056 pd->sctp_flags |= PFDESC_SCTP_INIT; 2057 else 2058 pd->sctp_flags |= PFDESC_SCTP_INIT_ACK; 2059 2060 ret = pf_multihome_scan_init(pd->off + chunk_start, 2061 ntohs(init.ch.chunk_length), pd); 2062 if (ret != PF_PASS) 2063 return (ret); 2064 2065 break; 2066 } 2067 case SCTP_ABORT_ASSOCIATION: 2068 pd->sctp_flags |= PFDESC_SCTP_ABORT; 2069 break; 2070 case SCTP_SHUTDOWN: 2071 case SCTP_SHUTDOWN_ACK: 2072 pd->sctp_flags |= PFDESC_SCTP_SHUTDOWN; 2073 break; 2074 case SCTP_SHUTDOWN_COMPLETE: 2075 pd->sctp_flags |= PFDESC_SCTP_SHUTDOWN_COMPLETE; 2076 break; 2077 case SCTP_COOKIE_ECHO: 2078 pd->sctp_flags |= PFDESC_SCTP_COOKIE; 2079 break; 2080 case SCTP_COOKIE_ACK: 2081 pd->sctp_flags |= PFDESC_SCTP_COOKIE_ACK; 2082 break; 2083 case SCTP_DATA: 2084 pd->sctp_flags |= PFDESC_SCTP_DATA; 2085 break; 2086 case SCTP_HEARTBEAT_REQUEST: 2087 pd->sctp_flags |= PFDESC_SCTP_HEARTBEAT; 2088 break; 2089 case SCTP_HEARTBEAT_ACK: 2090 pd->sctp_flags |= PFDESC_SCTP_HEARTBEAT_ACK; 2091 break; 2092 case SCTP_ASCONF: 2093 pd->sctp_flags |= PFDESC_SCTP_ASCONF; 2094 2095 ret = pf_multihome_scan_asconf(pd->off + chunk_start, 2096 ntohs(ch.chunk_length), pd); 2097 if (ret != PF_PASS) 2098 return (ret); 2099 break; 2100 default: 2101 pd->sctp_flags |= PFDESC_SCTP_OTHER; 2102 break; 2103 } 2104 } 2105 2106 /* Validate chunk lengths vs. packet length. */ 2107 if (pd->off + chunk_off != pd->tot_len) 2108 return (PF_DROP); 2109 2110 /* 2111 * INIT, INIT_ACK or SHUTDOWN_COMPLETE chunks must always be the only 2112 * one in a packet. 2113 */ 2114 if ((pd->sctp_flags & PFDESC_SCTP_INIT) && 2115 (pd->sctp_flags & ~PFDESC_SCTP_INIT)) 2116 return (PF_DROP); 2117 if ((pd->sctp_flags & PFDESC_SCTP_INIT_ACK) && 2118 (pd->sctp_flags & ~PFDESC_SCTP_INIT_ACK)) 2119 return (PF_DROP); 2120 if ((pd->sctp_flags & PFDESC_SCTP_SHUTDOWN_COMPLETE) && 2121 (pd->sctp_flags & ~PFDESC_SCTP_SHUTDOWN_COMPLETE)) 2122 return (PF_DROP); 2123 if ((pd->sctp_flags & PFDESC_SCTP_ABORT) && 2124 (pd->sctp_flags & PFDESC_SCTP_DATA)) { 2125 /* 2126 * RFC4960 3.3.7: DATA chunks MUST NOT be 2127 * bundled with ABORT. 2128 */ 2129 return (PF_DROP); 2130 } 2131 2132 return (PF_PASS); 2133 } 2134 2135 int 2136 pf_normalize_sctp(struct pf_pdesc *pd) 2137 { 2138 struct pf_krule *r, *rm = NULL; 2139 struct sctphdr *sh = &pd->hdr.sctp; 2140 u_short reason; 2141 sa_family_t af = pd->af; 2142 int srs; 2143 2144 PF_RULES_RASSERT(); 2145 2146 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 2147 /* Check if there any scrub rules. Lack of scrub rules means enforced 2148 * packet normalization operation just like in OpenBSD. */ 2149 srs = (r != NULL); 2150 while (r != NULL) { 2151 pf_counter_u64_add(&r->evaluations, 1); 2152 if (pfi_kkif_match(r->kif, pd->kif) == r->ifnot) 2153 r = r->skip[PF_SKIP_IFP]; 2154 else if (r->direction && r->direction != pd->dir) 2155 r = r->skip[PF_SKIP_DIR]; 2156 else if (r->af && r->af != af) 2157 r = r->skip[PF_SKIP_AF]; 2158 else if (r->proto && r->proto != pd->proto) 2159 r = r->skip[PF_SKIP_PROTO]; 2160 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, 2161 r->src.neg, pd->kif, M_GETFIB(pd->m))) 2162 r = r->skip[PF_SKIP_SRC_ADDR]; 2163 else if (r->src.port_op && !pf_match_port(r->src.port_op, 2164 r->src.port[0], r->src.port[1], sh->src_port)) 2165 r = r->skip[PF_SKIP_SRC_PORT]; 2166 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, 2167 r->dst.neg, NULL, M_GETFIB(pd->m))) 2168 r = r->skip[PF_SKIP_DST_ADDR]; 2169 else if (r->dst.port_op && !pf_match_port(r->dst.port_op, 2170 r->dst.port[0], r->dst.port[1], sh->dest_port)) 2171 r = r->skip[PF_SKIP_DST_PORT]; 2172 else { 2173 rm = r; 2174 break; 2175 } 2176 } 2177 2178 if (srs) { 2179 /* With scrub rules present SCTP normalization happens only 2180 * if one of rules has matched and it's not a "no scrub" rule */ 2181 if (rm == NULL || rm->action == PF_NOSCRUB) 2182 return (PF_PASS); 2183 2184 pf_counter_u64_critical_enter(); 2185 pf_counter_u64_add_protected(&r->packets[pd->dir == PF_OUT], 1); 2186 pf_counter_u64_add_protected(&r->bytes[pd->dir == PF_OUT], pd->tot_len); 2187 pf_counter_u64_critical_exit(); 2188 } 2189 2190 /* Verify we're a multiple of 4 bytes long */ 2191 if ((pd->tot_len - pd->off - sizeof(struct sctphdr)) % 4) 2192 goto sctp_drop; 2193 2194 /* INIT chunk needs to be the only chunk */ 2195 if (pd->sctp_flags & PFDESC_SCTP_INIT) 2196 if (pd->sctp_flags & ~PFDESC_SCTP_INIT) 2197 goto sctp_drop; 2198 2199 return (PF_PASS); 2200 2201 sctp_drop: 2202 REASON_SET(&reason, PFRES_NORM); 2203 if (rm != NULL && r->log) 2204 PFLOG_PACKET(PF_DROP, reason, r, NULL, NULL, pd, 2205 1, NULL); 2206 2207 return (PF_DROP); 2208 } 2209 2210 #if defined(INET) || defined(INET6) 2211 void 2212 pf_scrub(struct pf_pdesc *pd) 2213 { 2214 2215 struct ip *h = mtod(pd->m, struct ip *); 2216 #ifdef INET6 2217 struct ip6_hdr *h6 = mtod(pd->m, struct ip6_hdr *); 2218 #endif /* INET6 */ 2219 2220 /* Clear IP_DF if no-df was requested */ 2221 if (pd->af == AF_INET && pd->act.flags & PFSTATE_NODF && 2222 h->ip_off & htons(IP_DF)) 2223 { 2224 u_int16_t ip_off = h->ip_off; 2225 2226 h->ip_off &= htons(~IP_DF); 2227 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 2228 } 2229 2230 /* Enforce a minimum ttl, may cause endless packet loops */ 2231 if (pd->af == AF_INET && pd->act.min_ttl && 2232 h->ip_ttl < pd->act.min_ttl) { 2233 u_int16_t ip_ttl = h->ip_ttl; 2234 2235 h->ip_ttl = pd->act.min_ttl; 2236 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0); 2237 } 2238 #ifdef INET6 2239 /* Enforce a minimum ttl, may cause endless packet loops */ 2240 if (pd->af == AF_INET6 && pd->act.min_ttl && 2241 h6->ip6_hlim < pd->act.min_ttl) 2242 h6->ip6_hlim = pd->act.min_ttl; 2243 #endif /* INET6 */ 2244 /* Enforce tos */ 2245 if (pd->act.flags & PFSTATE_SETTOS) { 2246 switch (pd->af) { 2247 case AF_INET: { 2248 u_int16_t ov, nv; 2249 2250 ov = *(u_int16_t *)h; 2251 h->ip_tos = pd->act.set_tos | (h->ip_tos & IPTOS_ECN_MASK); 2252 nv = *(u_int16_t *)h; 2253 2254 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0); 2255 break; 2256 } 2257 #ifdef INET6 2258 case AF_INET6: 2259 h6->ip6_flow &= IPV6_FLOWLABEL_MASK | IPV6_VERSION_MASK; 2260 h6->ip6_flow |= htonl((pd->act.set_tos | IPV6_ECN(h6)) << 20); 2261 break; 2262 #endif /* INET6 */ 2263 } 2264 } 2265 2266 /* random-id, but not for fragments */ 2267 #ifdef INET 2268 if (pd->af == AF_INET && 2269 pd->act.flags & PFSTATE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) { 2270 uint16_t ip_id = h->ip_id; 2271 2272 ip_fillid(h, V_ip_random_id); 2273 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0); 2274 } 2275 #endif /* INET */ 2276 } 2277 #endif /* INET || INET6 */ 2278