1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright 2001 Niels Provos <provos@citi.umich.edu> 5 * Copyright 2011-2018 Alexander Bluhm <bluhm@openbsd.org> 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 * $OpenBSD: pf_norm.c,v 1.114 2009/01/29 14:11:45 henning Exp $ 29 */ 30 31 #include <sys/cdefs.h> 32 __FBSDID("$FreeBSD$"); 33 34 #include "opt_inet.h" 35 #include "opt_inet6.h" 36 #include "opt_pf.h" 37 38 #include <sys/param.h> 39 #include <sys/kernel.h> 40 #include <sys/lock.h> 41 #include <sys/mbuf.h> 42 #include <sys/mutex.h> 43 #include <sys/refcount.h> 44 #include <sys/socket.h> 45 46 #include <net/if.h> 47 #include <net/vnet.h> 48 #include <net/pfvar.h> 49 #include <net/if_pflog.h> 50 51 #include <netinet/in.h> 52 #include <netinet/ip.h> 53 #include <netinet/ip_var.h> 54 #include <netinet6/ip6_var.h> 55 #include <netinet6/scope6_var.h> 56 #include <netinet/tcp.h> 57 #include <netinet/tcp_fsm.h> 58 #include <netinet/tcp_seq.h> 59 60 #ifdef INET6 61 #include <netinet/ip6.h> 62 #endif /* INET6 */ 63 64 struct pf_frent { 65 TAILQ_ENTRY(pf_frent) fr_next; 66 struct mbuf *fe_m; 67 uint16_t fe_hdrlen; /* ipv4 header length with ip options 68 ipv6, extension, fragment header */ 69 uint16_t fe_extoff; /* last extension header offset or 0 */ 70 uint16_t fe_len; /* fragment length */ 71 uint16_t fe_off; /* fragment offset */ 72 uint16_t fe_mff; /* more fragment flag */ 73 }; 74 75 struct pf_fragment_cmp { 76 struct pf_addr frc_src; 77 struct pf_addr frc_dst; 78 uint32_t frc_id; 79 sa_family_t frc_af; 80 uint8_t frc_proto; 81 }; 82 83 struct pf_fragment { 84 struct pf_fragment_cmp fr_key; 85 #define fr_src fr_key.frc_src 86 #define fr_dst fr_key.frc_dst 87 #define fr_id fr_key.frc_id 88 #define fr_af fr_key.frc_af 89 #define fr_proto fr_key.frc_proto 90 91 /* pointers to queue element */ 92 struct pf_frent *fr_firstoff[PF_FRAG_ENTRY_POINTS]; 93 /* count entries between pointers */ 94 uint8_t fr_entries[PF_FRAG_ENTRY_POINTS]; 95 RB_ENTRY(pf_fragment) fr_entry; 96 TAILQ_ENTRY(pf_fragment) frag_next; 97 uint32_t fr_timeout; 98 uint16_t fr_maxlen; /* maximum length of single fragment */ 99 u_int16_t fr_holes; /* number of holes in the queue */ 100 TAILQ_HEAD(pf_fragq, pf_frent) fr_queue; 101 }; 102 103 struct pf_fragment_tag { 104 uint16_t ft_hdrlen; /* header length of reassembled pkt */ 105 uint16_t ft_extoff; /* last extension header offset or 0 */ 106 uint16_t ft_maxlen; /* maximum fragment payload length */ 107 uint32_t ft_id; /* fragment id */ 108 }; 109 110 VNET_DEFINE_STATIC(struct mtx, pf_frag_mtx); 111 #define V_pf_frag_mtx VNET(pf_frag_mtx) 112 #define PF_FRAG_LOCK() mtx_lock(&V_pf_frag_mtx) 113 #define PF_FRAG_UNLOCK() mtx_unlock(&V_pf_frag_mtx) 114 #define PF_FRAG_ASSERT() mtx_assert(&V_pf_frag_mtx, MA_OWNED) 115 116 VNET_DEFINE(uma_zone_t, pf_state_scrub_z); /* XXX: shared with pfsync */ 117 118 VNET_DEFINE_STATIC(uma_zone_t, pf_frent_z); 119 #define V_pf_frent_z VNET(pf_frent_z) 120 VNET_DEFINE_STATIC(uma_zone_t, pf_frag_z); 121 #define V_pf_frag_z VNET(pf_frag_z) 122 123 TAILQ_HEAD(pf_fragqueue, pf_fragment); 124 TAILQ_HEAD(pf_cachequeue, pf_fragment); 125 VNET_DEFINE_STATIC(struct pf_fragqueue, pf_fragqueue); 126 #define V_pf_fragqueue VNET(pf_fragqueue) 127 RB_HEAD(pf_frag_tree, pf_fragment); 128 VNET_DEFINE_STATIC(struct pf_frag_tree, pf_frag_tree); 129 #define V_pf_frag_tree VNET(pf_frag_tree) 130 static int pf_frag_compare(struct pf_fragment *, 131 struct pf_fragment *); 132 static RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 133 static RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 134 135 static void pf_flush_fragments(void); 136 static void pf_free_fragment(struct pf_fragment *); 137 static void pf_remove_fragment(struct pf_fragment *); 138 static int pf_normalize_tcpopt(struct pf_krule *, struct mbuf *, 139 struct tcphdr *, int, sa_family_t); 140 static struct pf_frent *pf_create_fragment(u_short *); 141 static int pf_frent_holes(struct pf_frent *frent); 142 static struct pf_fragment *pf_find_fragment(struct pf_fragment_cmp *key, 143 struct pf_frag_tree *tree); 144 static inline int pf_frent_index(struct pf_frent *); 145 static int pf_frent_insert(struct pf_fragment *, 146 struct pf_frent *, struct pf_frent *); 147 void pf_frent_remove(struct pf_fragment *, 148 struct pf_frent *); 149 struct pf_frent *pf_frent_previous(struct pf_fragment *, 150 struct pf_frent *); 151 static struct pf_fragment *pf_fillup_fragment(struct pf_fragment_cmp *, 152 struct pf_frent *, u_short *); 153 static struct mbuf *pf_join_fragment(struct pf_fragment *); 154 #ifdef INET 155 static void pf_scrub_ip(struct mbuf **, uint32_t, uint8_t, uint8_t); 156 static int pf_reassemble(struct mbuf **, struct ip *, int, u_short *); 157 #endif /* INET */ 158 #ifdef INET6 159 static int pf_reassemble6(struct mbuf **, struct ip6_hdr *, 160 struct ip6_frag *, uint16_t, uint16_t, u_short *); 161 static void pf_scrub_ip6(struct mbuf **, uint32_t, uint8_t, uint8_t); 162 #endif /* INET6 */ 163 164 #define DPFPRINTF(x) do { \ 165 if (V_pf_status.debug >= PF_DEBUG_MISC) { \ 166 printf("%s: ", __func__); \ 167 printf x ; \ 168 } \ 169 } while(0) 170 171 #ifdef INET 172 static void 173 pf_ip2key(struct ip *ip, int dir, struct pf_fragment_cmp *key) 174 { 175 176 key->frc_src.v4 = ip->ip_src; 177 key->frc_dst.v4 = ip->ip_dst; 178 key->frc_af = AF_INET; 179 key->frc_proto = ip->ip_p; 180 key->frc_id = ip->ip_id; 181 } 182 #endif /* INET */ 183 184 void 185 pf_normalize_init(void) 186 { 187 188 V_pf_frag_z = uma_zcreate("pf frags", sizeof(struct pf_fragment), 189 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 190 V_pf_frent_z = uma_zcreate("pf frag entries", sizeof(struct pf_frent), 191 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 192 V_pf_state_scrub_z = uma_zcreate("pf state scrubs", 193 sizeof(struct pf_state_scrub), NULL, NULL, NULL, NULL, 194 UMA_ALIGN_PTR, 0); 195 196 mtx_init(&V_pf_frag_mtx, "pf fragments", NULL, MTX_DEF); 197 198 V_pf_limits[PF_LIMIT_FRAGS].zone = V_pf_frent_z; 199 V_pf_limits[PF_LIMIT_FRAGS].limit = PFFRAG_FRENT_HIWAT; 200 uma_zone_set_max(V_pf_frent_z, PFFRAG_FRENT_HIWAT); 201 uma_zone_set_warning(V_pf_frent_z, "PF frag entries limit reached"); 202 203 TAILQ_INIT(&V_pf_fragqueue); 204 } 205 206 void 207 pf_normalize_cleanup(void) 208 { 209 210 uma_zdestroy(V_pf_state_scrub_z); 211 uma_zdestroy(V_pf_frent_z); 212 uma_zdestroy(V_pf_frag_z); 213 214 mtx_destroy(&V_pf_frag_mtx); 215 } 216 217 static int 218 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b) 219 { 220 int diff; 221 222 if ((diff = a->fr_id - b->fr_id) != 0) 223 return (diff); 224 if ((diff = a->fr_proto - b->fr_proto) != 0) 225 return (diff); 226 if ((diff = a->fr_af - b->fr_af) != 0) 227 return (diff); 228 if ((diff = pf_addr_cmp(&a->fr_src, &b->fr_src, a->fr_af)) != 0) 229 return (diff); 230 if ((diff = pf_addr_cmp(&a->fr_dst, &b->fr_dst, a->fr_af)) != 0) 231 return (diff); 232 return (0); 233 } 234 235 void 236 pf_purge_expired_fragments(void) 237 { 238 u_int32_t expire = time_uptime - 239 V_pf_default_rule.timeout[PFTM_FRAG]; 240 241 pf_purge_fragments(expire); 242 } 243 244 void 245 pf_purge_fragments(uint32_t expire) 246 { 247 struct pf_fragment *frag; 248 249 PF_FRAG_LOCK(); 250 while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) { 251 if (frag->fr_timeout > expire) 252 break; 253 254 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); 255 pf_free_fragment(frag); 256 } 257 258 PF_FRAG_UNLOCK(); 259 } 260 261 /* 262 * Try to flush old fragments to make space for new ones 263 */ 264 static void 265 pf_flush_fragments(void) 266 { 267 struct pf_fragment *frag; 268 int goal; 269 270 PF_FRAG_ASSERT(); 271 272 goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10; 273 DPFPRINTF(("trying to free %d frag entriess\n", goal)); 274 while (goal < uma_zone_get_cur(V_pf_frent_z)) { 275 frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue); 276 if (frag) 277 pf_free_fragment(frag); 278 else 279 break; 280 } 281 } 282 283 /* Frees the fragments and all associated entries */ 284 static void 285 pf_free_fragment(struct pf_fragment *frag) 286 { 287 struct pf_frent *frent; 288 289 PF_FRAG_ASSERT(); 290 291 /* Free all fragments */ 292 for (frent = TAILQ_FIRST(&frag->fr_queue); frent; 293 frent = TAILQ_FIRST(&frag->fr_queue)) { 294 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 295 296 m_freem(frent->fe_m); 297 uma_zfree(V_pf_frent_z, frent); 298 } 299 300 pf_remove_fragment(frag); 301 } 302 303 static struct pf_fragment * 304 pf_find_fragment(struct pf_fragment_cmp *key, struct pf_frag_tree *tree) 305 { 306 struct pf_fragment *frag; 307 308 PF_FRAG_ASSERT(); 309 310 frag = RB_FIND(pf_frag_tree, tree, (struct pf_fragment *)key); 311 if (frag != NULL) { 312 /* XXX Are we sure we want to update the timeout? */ 313 frag->fr_timeout = time_uptime; 314 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next); 315 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next); 316 } 317 318 return (frag); 319 } 320 321 /* Removes a fragment from the fragment queue and frees the fragment */ 322 static void 323 pf_remove_fragment(struct pf_fragment *frag) 324 { 325 326 PF_FRAG_ASSERT(); 327 KASSERT(frag, ("frag != NULL")); 328 329 RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag); 330 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next); 331 uma_zfree(V_pf_frag_z, frag); 332 } 333 334 static struct pf_frent * 335 pf_create_fragment(u_short *reason) 336 { 337 struct pf_frent *frent; 338 339 PF_FRAG_ASSERT(); 340 341 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT); 342 if (frent == NULL) { 343 pf_flush_fragments(); 344 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT); 345 if (frent == NULL) { 346 REASON_SET(reason, PFRES_MEMORY); 347 return (NULL); 348 } 349 } 350 351 return (frent); 352 } 353 354 /* 355 * Calculate the additional holes that were created in the fragment 356 * queue by inserting this fragment. A fragment in the middle 357 * creates one more hole by splitting. For each connected side, 358 * it loses one hole. 359 * Fragment entry must be in the queue when calling this function. 360 */ 361 static int 362 pf_frent_holes(struct pf_frent *frent) 363 { 364 struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next); 365 struct pf_frent *next = TAILQ_NEXT(frent, fr_next); 366 int holes = 1; 367 368 if (prev == NULL) { 369 if (frent->fe_off == 0) 370 holes--; 371 } else { 372 KASSERT(frent->fe_off != 0, ("frent->fe_off != 0")); 373 if (frent->fe_off == prev->fe_off + prev->fe_len) 374 holes--; 375 } 376 if (next == NULL) { 377 if (!frent->fe_mff) 378 holes--; 379 } else { 380 KASSERT(frent->fe_mff, ("frent->fe_mff")); 381 if (next->fe_off == frent->fe_off + frent->fe_len) 382 holes--; 383 } 384 return holes; 385 } 386 387 static inline int 388 pf_frent_index(struct pf_frent *frent) 389 { 390 /* 391 * We have an array of 16 entry points to the queue. A full size 392 * 65535 octet IP packet can have 8192 fragments. So the queue 393 * traversal length is at most 512 and at most 16 entry points are 394 * checked. We need 128 additional bytes on a 64 bit architecture. 395 */ 396 CTASSERT(((u_int16_t)0xffff &~ 7) / (0x10000 / PF_FRAG_ENTRY_POINTS) == 397 16 - 1); 398 CTASSERT(((u_int16_t)0xffff >> 3) / PF_FRAG_ENTRY_POINTS == 512 - 1); 399 400 return frent->fe_off / (0x10000 / PF_FRAG_ENTRY_POINTS); 401 } 402 403 static int 404 pf_frent_insert(struct pf_fragment *frag, struct pf_frent *frent, 405 struct pf_frent *prev) 406 { 407 int index; 408 409 CTASSERT(PF_FRAG_ENTRY_LIMIT <= 0xff); 410 411 /* 412 * A packet has at most 65536 octets. With 16 entry points, each one 413 * spawns 4096 octets. We limit these to 64 fragments each, which 414 * means on average every fragment must have at least 64 octets. 415 */ 416 index = pf_frent_index(frent); 417 if (frag->fr_entries[index] >= PF_FRAG_ENTRY_LIMIT) 418 return ENOBUFS; 419 frag->fr_entries[index]++; 420 421 if (prev == NULL) { 422 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next); 423 } else { 424 KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off, 425 ("overlapping fragment")); 426 TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next); 427 } 428 429 if (frag->fr_firstoff[index] == NULL) { 430 KASSERT(prev == NULL || pf_frent_index(prev) < index, 431 ("prev == NULL || pf_frent_index(pref) < index")); 432 frag->fr_firstoff[index] = frent; 433 } else { 434 if (frent->fe_off < frag->fr_firstoff[index]->fe_off) { 435 KASSERT(prev == NULL || pf_frent_index(prev) < index, 436 ("prev == NULL || pf_frent_index(pref) < index")); 437 frag->fr_firstoff[index] = frent; 438 } else { 439 KASSERT(prev != NULL, ("prev != NULL")); 440 KASSERT(pf_frent_index(prev) == index, 441 ("pf_frent_index(prev) == index")); 442 } 443 } 444 445 frag->fr_holes += pf_frent_holes(frent); 446 447 return 0; 448 } 449 450 void 451 pf_frent_remove(struct pf_fragment *frag, struct pf_frent *frent) 452 { 453 #ifdef INVARIANTS 454 struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next); 455 #endif 456 struct pf_frent *next = TAILQ_NEXT(frent, fr_next); 457 int index; 458 459 frag->fr_holes -= pf_frent_holes(frent); 460 461 index = pf_frent_index(frent); 462 KASSERT(frag->fr_firstoff[index] != NULL, ("frent not found")); 463 if (frag->fr_firstoff[index]->fe_off == frent->fe_off) { 464 if (next == NULL) { 465 frag->fr_firstoff[index] = NULL; 466 } else { 467 KASSERT(frent->fe_off + frent->fe_len <= next->fe_off, 468 ("overlapping fragment")); 469 if (pf_frent_index(next) == index) { 470 frag->fr_firstoff[index] = next; 471 } else { 472 frag->fr_firstoff[index] = NULL; 473 } 474 } 475 } else { 476 KASSERT(frag->fr_firstoff[index]->fe_off < frent->fe_off, 477 ("frag->fr_firstoff[index]->fe_off < frent->fe_off")); 478 KASSERT(prev != NULL, ("prev != NULL")); 479 KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off, 480 ("overlapping fragment")); 481 KASSERT(pf_frent_index(prev) == index, 482 ("pf_frent_index(prev) == index")); 483 } 484 485 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 486 487 KASSERT(frag->fr_entries[index] > 0, ("No fragments remaining")); 488 frag->fr_entries[index]--; 489 } 490 491 struct pf_frent * 492 pf_frent_previous(struct pf_fragment *frag, struct pf_frent *frent) 493 { 494 struct pf_frent *prev, *next; 495 int index; 496 497 /* 498 * If there are no fragments after frag, take the final one. Assume 499 * that the global queue is not empty. 500 */ 501 prev = TAILQ_LAST(&frag->fr_queue, pf_fragq); 502 KASSERT(prev != NULL, ("prev != NULL")); 503 if (prev->fe_off <= frent->fe_off) 504 return prev; 505 /* 506 * We want to find a fragment entry that is before frag, but still 507 * close to it. Find the first fragment entry that is in the same 508 * entry point or in the first entry point after that. As we have 509 * already checked that there are entries behind frag, this will 510 * succeed. 511 */ 512 for (index = pf_frent_index(frent); index < PF_FRAG_ENTRY_POINTS; 513 index++) { 514 prev = frag->fr_firstoff[index]; 515 if (prev != NULL) 516 break; 517 } 518 KASSERT(prev != NULL, ("prev != NULL")); 519 /* 520 * In prev we may have a fragment from the same entry point that is 521 * before frent, or one that is just one position behind frent. 522 * In the latter case, we go back one step and have the predecessor. 523 * There may be none if the new fragment will be the first one. 524 */ 525 if (prev->fe_off > frent->fe_off) { 526 prev = TAILQ_PREV(prev, pf_fragq, fr_next); 527 if (prev == NULL) 528 return NULL; 529 KASSERT(prev->fe_off <= frent->fe_off, 530 ("prev->fe_off <= frent->fe_off")); 531 return prev; 532 } 533 /* 534 * In prev is the first fragment of the entry point. The offset 535 * of frag is behind it. Find the closest previous fragment. 536 */ 537 for (next = TAILQ_NEXT(prev, fr_next); next != NULL; 538 next = TAILQ_NEXT(next, fr_next)) { 539 if (next->fe_off > frent->fe_off) 540 break; 541 prev = next; 542 } 543 return prev; 544 } 545 546 static struct pf_fragment * 547 pf_fillup_fragment(struct pf_fragment_cmp *key, struct pf_frent *frent, 548 u_short *reason) 549 { 550 struct pf_frent *after, *next, *prev; 551 struct pf_fragment *frag; 552 uint16_t total; 553 int old_index, new_index; 554 555 PF_FRAG_ASSERT(); 556 557 /* No empty fragments. */ 558 if (frent->fe_len == 0) { 559 DPFPRINTF(("bad fragment: len 0\n")); 560 goto bad_fragment; 561 } 562 563 /* All fragments are 8 byte aligned. */ 564 if (frent->fe_mff && (frent->fe_len & 0x7)) { 565 DPFPRINTF(("bad fragment: mff and len %d\n", frent->fe_len)); 566 goto bad_fragment; 567 } 568 569 /* Respect maximum length, IP_MAXPACKET == IPV6_MAXPACKET. */ 570 if (frent->fe_off + frent->fe_len > IP_MAXPACKET) { 571 DPFPRINTF(("bad fragment: max packet %d\n", 572 frent->fe_off + frent->fe_len)); 573 goto bad_fragment; 574 } 575 576 DPFPRINTF((key->frc_af == AF_INET ? 577 "reass frag %d @ %d-%d\n" : "reass frag %#08x @ %d-%d\n", 578 key->frc_id, frent->fe_off, frent->fe_off + frent->fe_len)); 579 580 /* Fully buffer all of the fragments in this fragment queue. */ 581 frag = pf_find_fragment(key, &V_pf_frag_tree); 582 583 /* Create a new reassembly queue for this packet. */ 584 if (frag == NULL) { 585 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 586 if (frag == NULL) { 587 pf_flush_fragments(); 588 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 589 if (frag == NULL) { 590 REASON_SET(reason, PFRES_MEMORY); 591 goto drop_fragment; 592 } 593 } 594 595 *(struct pf_fragment_cmp *)frag = *key; 596 memset(frag->fr_firstoff, 0, sizeof(frag->fr_firstoff)); 597 memset(frag->fr_entries, 0, sizeof(frag->fr_entries)); 598 frag->fr_timeout = time_uptime; 599 frag->fr_maxlen = frent->fe_len; 600 frag->fr_holes = 1; 601 TAILQ_INIT(&frag->fr_queue); 602 603 RB_INSERT(pf_frag_tree, &V_pf_frag_tree, frag); 604 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next); 605 606 /* We do not have a previous fragment, cannot fail. */ 607 pf_frent_insert(frag, frent, NULL); 608 609 return (frag); 610 } 611 612 KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue")); 613 614 /* Remember maximum fragment len for refragmentation. */ 615 if (frent->fe_len > frag->fr_maxlen) 616 frag->fr_maxlen = frent->fe_len; 617 618 /* Maximum data we have seen already. */ 619 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 620 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 621 622 /* Non terminal fragments must have more fragments flag. */ 623 if (frent->fe_off + frent->fe_len < total && !frent->fe_mff) 624 goto bad_fragment; 625 626 /* Check if we saw the last fragment already. */ 627 if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) { 628 if (frent->fe_off + frent->fe_len > total || 629 (frent->fe_off + frent->fe_len == total && frent->fe_mff)) 630 goto bad_fragment; 631 } else { 632 if (frent->fe_off + frent->fe_len == total && !frent->fe_mff) 633 goto bad_fragment; 634 } 635 636 /* Find neighbors for newly inserted fragment */ 637 prev = pf_frent_previous(frag, frent); 638 if (prev == NULL) { 639 after = TAILQ_FIRST(&frag->fr_queue); 640 KASSERT(after != NULL, ("after != NULL")); 641 } else { 642 after = TAILQ_NEXT(prev, fr_next); 643 } 644 645 if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) { 646 uint16_t precut; 647 648 precut = prev->fe_off + prev->fe_len - frent->fe_off; 649 if (precut >= frent->fe_len) 650 goto bad_fragment; 651 DPFPRINTF(("overlap -%d\n", precut)); 652 m_adj(frent->fe_m, precut); 653 frent->fe_off += precut; 654 frent->fe_len -= precut; 655 } 656 657 for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off; 658 after = next) { 659 uint16_t aftercut; 660 661 aftercut = frent->fe_off + frent->fe_len - after->fe_off; 662 DPFPRINTF(("adjust overlap %d\n", aftercut)); 663 if (aftercut < after->fe_len) { 664 m_adj(after->fe_m, aftercut); 665 old_index = pf_frent_index(after); 666 after->fe_off += aftercut; 667 after->fe_len -= aftercut; 668 new_index = pf_frent_index(after); 669 if (old_index != new_index) { 670 DPFPRINTF(("frag index %d, new %d", 671 old_index, new_index)); 672 /* Fragment switched queue as fe_off changed */ 673 after->fe_off -= aftercut; 674 after->fe_len += aftercut; 675 /* Remove restored fragment from old queue */ 676 pf_frent_remove(frag, after); 677 after->fe_off += aftercut; 678 after->fe_len -= aftercut; 679 /* Insert into correct queue */ 680 if (pf_frent_insert(frag, after, prev)) { 681 DPFPRINTF( 682 ("fragment requeue limit exceeded")); 683 m_freem(after->fe_m); 684 uma_zfree(V_pf_frent_z, after); 685 /* There is not way to recover */ 686 goto bad_fragment; 687 } 688 } 689 break; 690 } 691 692 /* This fragment is completely overlapped, lose it. */ 693 next = TAILQ_NEXT(after, fr_next); 694 pf_frent_remove(frag, after); 695 m_freem(after->fe_m); 696 uma_zfree(V_pf_frent_z, after); 697 } 698 699 /* If part of the queue gets too long, there is not way to recover. */ 700 if (pf_frent_insert(frag, frent, prev)) { 701 DPFPRINTF(("fragment queue limit exceeded\n")); 702 goto bad_fragment; 703 } 704 705 return (frag); 706 707 bad_fragment: 708 REASON_SET(reason, PFRES_FRAG); 709 drop_fragment: 710 uma_zfree(V_pf_frent_z, frent); 711 return (NULL); 712 } 713 714 static struct mbuf * 715 pf_join_fragment(struct pf_fragment *frag) 716 { 717 struct mbuf *m, *m2; 718 struct pf_frent *frent, *next; 719 720 frent = TAILQ_FIRST(&frag->fr_queue); 721 next = TAILQ_NEXT(frent, fr_next); 722 723 m = frent->fe_m; 724 m_adj(m, (frent->fe_hdrlen + frent->fe_len) - m->m_pkthdr.len); 725 uma_zfree(V_pf_frent_z, frent); 726 for (frent = next; frent != NULL; frent = next) { 727 next = TAILQ_NEXT(frent, fr_next); 728 729 m2 = frent->fe_m; 730 /* Strip off ip header. */ 731 m_adj(m2, frent->fe_hdrlen); 732 /* Strip off any trailing bytes. */ 733 m_adj(m2, frent->fe_len - m2->m_pkthdr.len); 734 735 uma_zfree(V_pf_frent_z, frent); 736 m_cat(m, m2); 737 } 738 739 /* Remove from fragment queue. */ 740 pf_remove_fragment(frag); 741 742 return (m); 743 } 744 745 #ifdef INET 746 static int 747 pf_reassemble(struct mbuf **m0, struct ip *ip, int dir, u_short *reason) 748 { 749 struct mbuf *m = *m0; 750 struct pf_frent *frent; 751 struct pf_fragment *frag; 752 struct pf_fragment_cmp key; 753 uint16_t total, hdrlen; 754 755 /* Get an entry for the fragment queue */ 756 if ((frent = pf_create_fragment(reason)) == NULL) 757 return (PF_DROP); 758 759 frent->fe_m = m; 760 frent->fe_hdrlen = ip->ip_hl << 2; 761 frent->fe_extoff = 0; 762 frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2); 763 frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3; 764 frent->fe_mff = ntohs(ip->ip_off) & IP_MF; 765 766 pf_ip2key(ip, dir, &key); 767 768 if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) 769 return (PF_DROP); 770 771 /* The mbuf is part of the fragment entry, no direct free or access */ 772 m = *m0 = NULL; 773 774 if (frag->fr_holes) { 775 DPFPRINTF(("frag %d, holes %d\n", frag->fr_id, frag->fr_holes)); 776 return (PF_PASS); /* drop because *m0 is NULL, no error */ 777 } 778 779 /* We have all the data */ 780 frent = TAILQ_FIRST(&frag->fr_queue); 781 KASSERT(frent != NULL, ("frent != NULL")); 782 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 783 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 784 hdrlen = frent->fe_hdrlen; 785 786 m = *m0 = pf_join_fragment(frag); 787 frag = NULL; 788 789 if (m->m_flags & M_PKTHDR) { 790 int plen = 0; 791 for (m = *m0; m; m = m->m_next) 792 plen += m->m_len; 793 m = *m0; 794 m->m_pkthdr.len = plen; 795 } 796 797 ip = mtod(m, struct ip *); 798 ip->ip_sum = pf_cksum_fixup(ip->ip_sum, ip->ip_len, 799 htons(hdrlen + total), 0); 800 ip->ip_len = htons(hdrlen + total); 801 ip->ip_sum = pf_cksum_fixup(ip->ip_sum, ip->ip_off, 802 ip->ip_off & ~(IP_MF|IP_OFFMASK), 0); 803 ip->ip_off &= ~(IP_MF|IP_OFFMASK); 804 805 if (hdrlen + total > IP_MAXPACKET) { 806 DPFPRINTF(("drop: too big: %d\n", total)); 807 ip->ip_len = 0; 808 REASON_SET(reason, PFRES_SHORT); 809 /* PF_DROP requires a valid mbuf *m0 in pf_test() */ 810 return (PF_DROP); 811 } 812 813 DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len))); 814 return (PF_PASS); 815 } 816 #endif /* INET */ 817 818 #ifdef INET6 819 static int 820 pf_reassemble6(struct mbuf **m0, struct ip6_hdr *ip6, struct ip6_frag *fraghdr, 821 uint16_t hdrlen, uint16_t extoff, u_short *reason) 822 { 823 struct mbuf *m = *m0; 824 struct pf_frent *frent; 825 struct pf_fragment *frag; 826 struct pf_fragment_cmp key; 827 struct m_tag *mtag; 828 struct pf_fragment_tag *ftag; 829 int off; 830 uint32_t frag_id; 831 uint16_t total, maxlen; 832 uint8_t proto; 833 834 PF_FRAG_LOCK(); 835 836 /* Get an entry for the fragment queue. */ 837 if ((frent = pf_create_fragment(reason)) == NULL) { 838 PF_FRAG_UNLOCK(); 839 return (PF_DROP); 840 } 841 842 frent->fe_m = m; 843 frent->fe_hdrlen = hdrlen; 844 frent->fe_extoff = extoff; 845 frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen; 846 frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK); 847 frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG; 848 849 key.frc_src.v6 = ip6->ip6_src; 850 key.frc_dst.v6 = ip6->ip6_dst; 851 key.frc_af = AF_INET6; 852 /* Only the first fragment's protocol is relevant. */ 853 key.frc_proto = 0; 854 key.frc_id = fraghdr->ip6f_ident; 855 856 if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) { 857 PF_FRAG_UNLOCK(); 858 return (PF_DROP); 859 } 860 861 /* The mbuf is part of the fragment entry, no direct free or access. */ 862 m = *m0 = NULL; 863 864 if (frag->fr_holes) { 865 DPFPRINTF(("frag %d, holes %d\n", frag->fr_id, 866 frag->fr_holes)); 867 PF_FRAG_UNLOCK(); 868 return (PF_PASS); /* Drop because *m0 is NULL, no error. */ 869 } 870 871 /* We have all the data. */ 872 frent = TAILQ_FIRST(&frag->fr_queue); 873 KASSERT(frent != NULL, ("frent != NULL")); 874 extoff = frent->fe_extoff; 875 maxlen = frag->fr_maxlen; 876 frag_id = frag->fr_id; 877 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 878 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 879 hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag); 880 881 m = *m0 = pf_join_fragment(frag); 882 frag = NULL; 883 884 PF_FRAG_UNLOCK(); 885 886 /* Take protocol from first fragment header. */ 887 m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off); 888 KASSERT(m, ("%s: short mbuf chain", __func__)); 889 proto = *(mtod(m, caddr_t) + off); 890 m = *m0; 891 892 /* Delete frag6 header */ 893 if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0) 894 goto fail; 895 896 if (m->m_flags & M_PKTHDR) { 897 int plen = 0; 898 for (m = *m0; m; m = m->m_next) 899 plen += m->m_len; 900 m = *m0; 901 m->m_pkthdr.len = plen; 902 } 903 904 if ((mtag = m_tag_get(PF_REASSEMBLED, sizeof(struct pf_fragment_tag), 905 M_NOWAIT)) == NULL) 906 goto fail; 907 ftag = (struct pf_fragment_tag *)(mtag + 1); 908 ftag->ft_hdrlen = hdrlen; 909 ftag->ft_extoff = extoff; 910 ftag->ft_maxlen = maxlen; 911 ftag->ft_id = frag_id; 912 m_tag_prepend(m, mtag); 913 914 ip6 = mtod(m, struct ip6_hdr *); 915 ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total); 916 if (extoff) { 917 /* Write protocol into next field of last extension header. */ 918 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt), 919 &off); 920 KASSERT(m, ("%s: short mbuf chain", __func__)); 921 *(mtod(m, char *) + off) = proto; 922 m = *m0; 923 } else 924 ip6->ip6_nxt = proto; 925 926 if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) { 927 DPFPRINTF(("drop: too big: %d\n", total)); 928 ip6->ip6_plen = 0; 929 REASON_SET(reason, PFRES_SHORT); 930 /* PF_DROP requires a valid mbuf *m0 in pf_test6(). */ 931 return (PF_DROP); 932 } 933 934 DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip6->ip6_plen))); 935 return (PF_PASS); 936 937 fail: 938 REASON_SET(reason, PFRES_MEMORY); 939 /* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */ 940 return (PF_DROP); 941 } 942 #endif /* INET6 */ 943 944 #ifdef INET6 945 int 946 pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag, 947 bool forward) 948 { 949 struct mbuf *m = *m0, *t; 950 struct ip6_hdr *hdr; 951 struct pf_fragment_tag *ftag = (struct pf_fragment_tag *)(mtag + 1); 952 struct pf_pdesc pd; 953 uint32_t frag_id; 954 uint16_t hdrlen, extoff, maxlen; 955 uint8_t proto; 956 int error, action; 957 958 hdrlen = ftag->ft_hdrlen; 959 extoff = ftag->ft_extoff; 960 maxlen = ftag->ft_maxlen; 961 frag_id = ftag->ft_id; 962 m_tag_delete(m, mtag); 963 mtag = NULL; 964 ftag = NULL; 965 966 if (extoff) { 967 int off; 968 969 /* Use protocol from next field of last extension header */ 970 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt), 971 &off); 972 KASSERT((m != NULL), ("pf_refragment6: short mbuf chain")); 973 proto = *(mtod(m, caddr_t) + off); 974 *(mtod(m, char *) + off) = IPPROTO_FRAGMENT; 975 m = *m0; 976 } else { 977 hdr = mtod(m, struct ip6_hdr *); 978 proto = hdr->ip6_nxt; 979 hdr->ip6_nxt = IPPROTO_FRAGMENT; 980 } 981 982 /* In case of link-local traffic we'll need a scope set. */ 983 hdr = mtod(m, struct ip6_hdr *); 984 985 in6_setscope(&hdr->ip6_src, ifp, NULL); 986 in6_setscope(&hdr->ip6_dst, ifp, NULL); 987 988 /* The MTU must be a multiple of 8 bytes, or we risk doing the 989 * fragmentation wrong. */ 990 maxlen = maxlen & ~7; 991 992 /* 993 * Maxlen may be less than 8 if there was only a single 994 * fragment. As it was fragmented before, add a fragment 995 * header also for a single fragment. If total or maxlen 996 * is less than 8, ip6_fragment() will return EMSGSIZE and 997 * we drop the packet. 998 */ 999 error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id); 1000 m = (*m0)->m_nextpkt; 1001 (*m0)->m_nextpkt = NULL; 1002 if (error == 0) { 1003 /* The first mbuf contains the unfragmented packet. */ 1004 m_freem(*m0); 1005 *m0 = NULL; 1006 action = PF_PASS; 1007 } else { 1008 /* Drop expects an mbuf to free. */ 1009 DPFPRINTF(("refragment error %d\n", error)); 1010 action = PF_DROP; 1011 } 1012 for (; m; m = t) { 1013 t = m->m_nextpkt; 1014 m->m_nextpkt = NULL; 1015 m->m_flags |= M_SKIP_FIREWALL; 1016 memset(&pd, 0, sizeof(pd)); 1017 pd.pf_mtag = pf_find_mtag(m); 1018 if (error == 0) 1019 if (forward) { 1020 MPASS(m->m_pkthdr.rcvif != NULL); 1021 ip6_forward(m, 0); 1022 } else { 1023 (void)ip6_output(m, NULL, NULL, 0, NULL, NULL, 1024 NULL); 1025 } 1026 else 1027 m_freem(m); 1028 } 1029 1030 return (action); 1031 } 1032 #endif /* INET6 */ 1033 1034 #ifdef INET 1035 int 1036 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kkif *kif, u_short *reason, 1037 struct pf_pdesc *pd) 1038 { 1039 struct mbuf *m = *m0; 1040 struct pf_krule *r; 1041 struct ip *h = mtod(m, struct ip *); 1042 int mff = (ntohs(h->ip_off) & IP_MF); 1043 int hlen = h->ip_hl << 2; 1044 u_int16_t fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3; 1045 u_int16_t max; 1046 int ip_len; 1047 int tag = -1; 1048 int verdict; 1049 1050 PF_RULES_RASSERT(); 1051 1052 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1053 while (r != NULL) { 1054 pf_counter_u64_add(&r->evaluations, 1); 1055 if (pfi_kkif_match(r->kif, kif) == r->ifnot) 1056 r = r->skip[PF_SKIP_IFP].ptr; 1057 else if (r->direction && r->direction != dir) 1058 r = r->skip[PF_SKIP_DIR].ptr; 1059 else if (r->af && r->af != AF_INET) 1060 r = r->skip[PF_SKIP_AF].ptr; 1061 else if (r->proto && r->proto != h->ip_p) 1062 r = r->skip[PF_SKIP_PROTO].ptr; 1063 else if (PF_MISMATCHAW(&r->src.addr, 1064 (struct pf_addr *)&h->ip_src.s_addr, AF_INET, 1065 r->src.neg, kif, M_GETFIB(m))) 1066 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1067 else if (PF_MISMATCHAW(&r->dst.addr, 1068 (struct pf_addr *)&h->ip_dst.s_addr, AF_INET, 1069 r->dst.neg, NULL, M_GETFIB(m))) 1070 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1071 else if (r->match_tag && !pf_match_tag(m, r, &tag, 1072 pd->pf_mtag ? pd->pf_mtag->tag : 0)) 1073 r = TAILQ_NEXT(r, entries); 1074 else 1075 break; 1076 } 1077 1078 if (r == NULL || r->action == PF_NOSCRUB) 1079 return (PF_PASS); 1080 1081 pf_counter_u64_critical_enter(); 1082 pf_counter_u64_add_protected(&r->packets[dir == PF_OUT], 1); 1083 pf_counter_u64_add_protected(&r->bytes[dir == PF_OUT], pd->tot_len); 1084 pf_counter_u64_critical_exit(); 1085 1086 /* Check for illegal packets */ 1087 if (hlen < (int)sizeof(struct ip)) { 1088 REASON_SET(reason, PFRES_NORM); 1089 goto drop; 1090 } 1091 1092 if (hlen > ntohs(h->ip_len)) { 1093 REASON_SET(reason, PFRES_NORM); 1094 goto drop; 1095 } 1096 1097 /* Clear IP_DF if the rule uses the no-df option */ 1098 if (r->rule_flag & PFRULE_NODF && h->ip_off & htons(IP_DF)) { 1099 u_int16_t ip_off = h->ip_off; 1100 1101 h->ip_off &= htons(~IP_DF); 1102 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1103 } 1104 1105 /* We will need other tests here */ 1106 if (!fragoff && !mff) 1107 goto no_fragment; 1108 1109 /* We're dealing with a fragment now. Don't allow fragments 1110 * with IP_DF to enter the cache. If the flag was cleared by 1111 * no-df above, fine. Otherwise drop it. 1112 */ 1113 if (h->ip_off & htons(IP_DF)) { 1114 DPFPRINTF(("IP_DF\n")); 1115 goto bad; 1116 } 1117 1118 ip_len = ntohs(h->ip_len) - hlen; 1119 1120 /* All fragments are 8 byte aligned */ 1121 if (mff && (ip_len & 0x7)) { 1122 DPFPRINTF(("mff and %d\n", ip_len)); 1123 goto bad; 1124 } 1125 1126 /* Respect maximum length */ 1127 if (fragoff + ip_len > IP_MAXPACKET) { 1128 DPFPRINTF(("max packet %d\n", fragoff + ip_len)); 1129 goto bad; 1130 } 1131 1132 if (! (r->rule_flag & PFRULE_FRAGMENT_NOREASS)) { 1133 max = fragoff + ip_len; 1134 1135 /* Fully buffer all of the fragments 1136 * Might return a completely reassembled mbuf, or NULL */ 1137 PF_FRAG_LOCK(); 1138 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max)); 1139 verdict = pf_reassemble(m0, h, dir, reason); 1140 PF_FRAG_UNLOCK(); 1141 1142 if (verdict != PF_PASS) 1143 return (PF_DROP); 1144 1145 m = *m0; 1146 if (m == NULL) 1147 return (PF_DROP); 1148 1149 h = mtod(m, struct ip *); 1150 1151 no_fragment: 1152 /* At this point, only IP_DF is allowed in ip_off */ 1153 if (h->ip_off & ~htons(IP_DF)) { 1154 u_int16_t ip_off = h->ip_off; 1155 1156 h->ip_off &= htons(IP_DF); 1157 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1158 } 1159 } 1160 1161 pf_scrub_ip(&m, r->rule_flag, r->min_ttl, r->set_tos); 1162 1163 return (PF_PASS); 1164 1165 bad: 1166 DPFPRINTF(("dropping bad fragment\n")); 1167 REASON_SET(reason, PFRES_FRAG); 1168 drop: 1169 if (r != NULL && r->log) 1170 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd, 1171 1); 1172 1173 return (PF_DROP); 1174 } 1175 #endif 1176 1177 #ifdef INET6 1178 int 1179 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kkif *kif, 1180 u_short *reason, struct pf_pdesc *pd) 1181 { 1182 struct mbuf *m = *m0; 1183 struct pf_krule *r; 1184 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1185 int extoff; 1186 int off; 1187 struct ip6_ext ext; 1188 struct ip6_opt opt; 1189 struct ip6_frag frag; 1190 u_int32_t plen; 1191 int optend; 1192 int ooff; 1193 u_int8_t proto; 1194 int terminal; 1195 1196 PF_RULES_RASSERT(); 1197 1198 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1199 while (r != NULL) { 1200 pf_counter_u64_add(&r->evaluations, 1); 1201 if (pfi_kkif_match(r->kif, kif) == r->ifnot) 1202 r = r->skip[PF_SKIP_IFP].ptr; 1203 else if (r->direction && r->direction != dir) 1204 r = r->skip[PF_SKIP_DIR].ptr; 1205 else if (r->af && r->af != AF_INET6) 1206 r = r->skip[PF_SKIP_AF].ptr; 1207 #if 0 /* header chain! */ 1208 else if (r->proto && r->proto != h->ip6_nxt) 1209 r = r->skip[PF_SKIP_PROTO].ptr; 1210 #endif 1211 else if (PF_MISMATCHAW(&r->src.addr, 1212 (struct pf_addr *)&h->ip6_src, AF_INET6, 1213 r->src.neg, kif, M_GETFIB(m))) 1214 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1215 else if (PF_MISMATCHAW(&r->dst.addr, 1216 (struct pf_addr *)&h->ip6_dst, AF_INET6, 1217 r->dst.neg, NULL, M_GETFIB(m))) 1218 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1219 else 1220 break; 1221 } 1222 1223 if (r == NULL || r->action == PF_NOSCRUB) 1224 return (PF_PASS); 1225 1226 pf_counter_u64_critical_enter(); 1227 pf_counter_u64_add_protected(&r->packets[dir == PF_OUT], 1); 1228 pf_counter_u64_add_protected(&r->bytes[dir == PF_OUT], pd->tot_len); 1229 pf_counter_u64_critical_exit(); 1230 1231 /* Check for illegal packets */ 1232 if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len) 1233 goto drop; 1234 1235 plen = ntohs(h->ip6_plen); 1236 /* jumbo payload option not supported */ 1237 if (plen == 0) 1238 goto drop; 1239 1240 extoff = 0; 1241 off = sizeof(struct ip6_hdr); 1242 proto = h->ip6_nxt; 1243 terminal = 0; 1244 do { 1245 switch (proto) { 1246 case IPPROTO_FRAGMENT: 1247 goto fragment; 1248 break; 1249 case IPPROTO_AH: 1250 case IPPROTO_ROUTING: 1251 case IPPROTO_DSTOPTS: 1252 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1253 NULL, AF_INET6)) 1254 goto shortpkt; 1255 extoff = off; 1256 if (proto == IPPROTO_AH) 1257 off += (ext.ip6e_len + 2) * 4; 1258 else 1259 off += (ext.ip6e_len + 1) * 8; 1260 proto = ext.ip6e_nxt; 1261 break; 1262 case IPPROTO_HOPOPTS: 1263 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1264 NULL, AF_INET6)) 1265 goto shortpkt; 1266 extoff = off; 1267 optend = off + (ext.ip6e_len + 1) * 8; 1268 ooff = off + sizeof(ext); 1269 do { 1270 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type, 1271 sizeof(opt.ip6o_type), NULL, NULL, 1272 AF_INET6)) 1273 goto shortpkt; 1274 if (opt.ip6o_type == IP6OPT_PAD1) { 1275 ooff++; 1276 continue; 1277 } 1278 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt), 1279 NULL, NULL, AF_INET6)) 1280 goto shortpkt; 1281 if (ooff + sizeof(opt) + opt.ip6o_len > optend) 1282 goto drop; 1283 if (opt.ip6o_type == IP6OPT_JUMBO) 1284 goto drop; 1285 ooff += sizeof(opt) + opt.ip6o_len; 1286 } while (ooff < optend); 1287 1288 off = optend; 1289 proto = ext.ip6e_nxt; 1290 break; 1291 default: 1292 terminal = 1; 1293 break; 1294 } 1295 } while (!terminal); 1296 1297 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1298 goto shortpkt; 1299 1300 pf_scrub_ip6(&m, r->rule_flag, r->min_ttl, r->set_tos); 1301 1302 return (PF_PASS); 1303 1304 fragment: 1305 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1306 goto shortpkt; 1307 1308 if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6)) 1309 goto shortpkt; 1310 1311 /* Offset now points to data portion. */ 1312 off += sizeof(frag); 1313 1314 /* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */ 1315 if (pf_reassemble6(m0, h, &frag, off, extoff, reason) != PF_PASS) 1316 return (PF_DROP); 1317 m = *m0; 1318 if (m == NULL) 1319 return (PF_DROP); 1320 1321 pd->flags |= PFDESC_IP_REAS; 1322 return (PF_PASS); 1323 1324 shortpkt: 1325 REASON_SET(reason, PFRES_SHORT); 1326 if (r != NULL && r->log) 1327 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd, 1328 1); 1329 return (PF_DROP); 1330 1331 drop: 1332 REASON_SET(reason, PFRES_NORM); 1333 if (r != NULL && r->log) 1334 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd, 1335 1); 1336 return (PF_DROP); 1337 } 1338 #endif /* INET6 */ 1339 1340 int 1341 pf_normalize_tcp(int dir, struct pfi_kkif *kif, struct mbuf *m, int ipoff, 1342 int off, void *h, struct pf_pdesc *pd) 1343 { 1344 struct pf_krule *r, *rm = NULL; 1345 struct tcphdr *th = &pd->hdr.tcp; 1346 int rewrite = 0; 1347 u_short reason; 1348 u_int8_t flags; 1349 sa_family_t af = pd->af; 1350 1351 PF_RULES_RASSERT(); 1352 1353 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1354 while (r != NULL) { 1355 pf_counter_u64_add(&r->evaluations, 1); 1356 if (pfi_kkif_match(r->kif, kif) == r->ifnot) 1357 r = r->skip[PF_SKIP_IFP].ptr; 1358 else if (r->direction && r->direction != dir) 1359 r = r->skip[PF_SKIP_DIR].ptr; 1360 else if (r->af && r->af != af) 1361 r = r->skip[PF_SKIP_AF].ptr; 1362 else if (r->proto && r->proto != pd->proto) 1363 r = r->skip[PF_SKIP_PROTO].ptr; 1364 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, 1365 r->src.neg, kif, M_GETFIB(m))) 1366 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1367 else if (r->src.port_op && !pf_match_port(r->src.port_op, 1368 r->src.port[0], r->src.port[1], th->th_sport)) 1369 r = r->skip[PF_SKIP_SRC_PORT].ptr; 1370 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, 1371 r->dst.neg, NULL, M_GETFIB(m))) 1372 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1373 else if (r->dst.port_op && !pf_match_port(r->dst.port_op, 1374 r->dst.port[0], r->dst.port[1], th->th_dport)) 1375 r = r->skip[PF_SKIP_DST_PORT].ptr; 1376 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match( 1377 pf_osfp_fingerprint(pd, m, off, th), 1378 r->os_fingerprint)) 1379 r = TAILQ_NEXT(r, entries); 1380 else { 1381 rm = r; 1382 break; 1383 } 1384 } 1385 1386 if (rm == NULL || rm->action == PF_NOSCRUB) 1387 return (PF_PASS); 1388 1389 pf_counter_u64_critical_enter(); 1390 pf_counter_u64_add_protected(&r->packets[dir == PF_OUT], 1); 1391 pf_counter_u64_add_protected(&r->bytes[dir == PF_OUT], pd->tot_len); 1392 pf_counter_u64_critical_exit(); 1393 1394 if (rm->rule_flag & PFRULE_REASSEMBLE_TCP) 1395 pd->flags |= PFDESC_TCP_NORM; 1396 1397 flags = th->th_flags; 1398 if (flags & TH_SYN) { 1399 /* Illegal packet */ 1400 if (flags & TH_RST) 1401 goto tcp_drop; 1402 1403 if (flags & TH_FIN) 1404 goto tcp_drop; 1405 } else { 1406 /* Illegal packet */ 1407 if (!(flags & (TH_ACK|TH_RST))) 1408 goto tcp_drop; 1409 } 1410 1411 if (!(flags & TH_ACK)) { 1412 /* These flags are only valid if ACK is set */ 1413 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG)) 1414 goto tcp_drop; 1415 } 1416 1417 /* Check for illegal header length */ 1418 if (th->th_off < (sizeof(struct tcphdr) >> 2)) 1419 goto tcp_drop; 1420 1421 /* If flags changed, or reserved data set, then adjust */ 1422 if (flags != th->th_flags || th->th_x2 != 0) { 1423 u_int16_t ov, nv; 1424 1425 ov = *(u_int16_t *)(&th->th_ack + 1); 1426 th->th_flags = flags; 1427 th->th_x2 = 0; 1428 nv = *(u_int16_t *)(&th->th_ack + 1); 1429 1430 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, ov, nv, 0); 1431 rewrite = 1; 1432 } 1433 1434 /* Remove urgent pointer, if TH_URG is not set */ 1435 if (!(flags & TH_URG) && th->th_urp) { 1436 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, th->th_urp, 1437 0, 0); 1438 th->th_urp = 0; 1439 rewrite = 1; 1440 } 1441 1442 /* Process options */ 1443 if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af)) 1444 rewrite = 1; 1445 1446 /* copy back packet headers if we sanitized */ 1447 if (rewrite) 1448 m_copyback(m, off, sizeof(*th), (caddr_t)th); 1449 1450 return (PF_PASS); 1451 1452 tcp_drop: 1453 REASON_SET(&reason, PFRES_NORM); 1454 if (rm != NULL && r->log) 1455 PFLOG_PACKET(kif, m, AF_INET, dir, reason, r, NULL, NULL, pd, 1456 1); 1457 return (PF_DROP); 1458 } 1459 1460 int 1461 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd, 1462 struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst) 1463 { 1464 u_int32_t tsval, tsecr; 1465 u_int8_t hdr[60]; 1466 u_int8_t *opt; 1467 1468 KASSERT((src->scrub == NULL), 1469 ("pf_normalize_tcp_init: src->scrub != NULL")); 1470 1471 src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT); 1472 if (src->scrub == NULL) 1473 return (1); 1474 1475 switch (pd->af) { 1476 #ifdef INET 1477 case AF_INET: { 1478 struct ip *h = mtod(m, struct ip *); 1479 src->scrub->pfss_ttl = h->ip_ttl; 1480 break; 1481 } 1482 #endif /* INET */ 1483 #ifdef INET6 1484 case AF_INET6: { 1485 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1486 src->scrub->pfss_ttl = h->ip6_hlim; 1487 break; 1488 } 1489 #endif /* INET6 */ 1490 } 1491 1492 /* 1493 * All normalizations below are only begun if we see the start of 1494 * the connections. They must all set an enabled bit in pfss_flags 1495 */ 1496 if ((th->th_flags & TH_SYN) == 0) 1497 return (0); 1498 1499 if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub && 1500 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1501 /* Diddle with TCP options */ 1502 int hlen; 1503 opt = hdr + sizeof(struct tcphdr); 1504 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1505 while (hlen >= TCPOLEN_TIMESTAMP) { 1506 switch (*opt) { 1507 case TCPOPT_EOL: /* FALLTHROUGH */ 1508 case TCPOPT_NOP: 1509 opt++; 1510 hlen--; 1511 break; 1512 case TCPOPT_TIMESTAMP: 1513 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1514 src->scrub->pfss_flags |= 1515 PFSS_TIMESTAMP; 1516 src->scrub->pfss_ts_mod = 1517 htonl(arc4random()); 1518 1519 /* note PFSS_PAWS not set yet */ 1520 memcpy(&tsval, &opt[2], 1521 sizeof(u_int32_t)); 1522 memcpy(&tsecr, &opt[6], 1523 sizeof(u_int32_t)); 1524 src->scrub->pfss_tsval0 = ntohl(tsval); 1525 src->scrub->pfss_tsval = ntohl(tsval); 1526 src->scrub->pfss_tsecr = ntohl(tsecr); 1527 getmicrouptime(&src->scrub->pfss_last); 1528 } 1529 /* FALLTHROUGH */ 1530 default: 1531 hlen -= MAX(opt[1], 2); 1532 opt += MAX(opt[1], 2); 1533 break; 1534 } 1535 } 1536 } 1537 1538 return (0); 1539 } 1540 1541 void 1542 pf_normalize_tcp_cleanup(struct pf_kstate *state) 1543 { 1544 if (state->src.scrub) 1545 uma_zfree(V_pf_state_scrub_z, state->src.scrub); 1546 if (state->dst.scrub) 1547 uma_zfree(V_pf_state_scrub_z, state->dst.scrub); 1548 1549 /* Someday... flush the TCP segment reassembly descriptors. */ 1550 } 1551 1552 int 1553 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd, 1554 u_short *reason, struct tcphdr *th, struct pf_kstate *state, 1555 struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback) 1556 { 1557 struct timeval uptime; 1558 u_int32_t tsval, tsecr; 1559 u_int tsval_from_last; 1560 u_int8_t hdr[60]; 1561 u_int8_t *opt; 1562 int copyback = 0; 1563 int got_ts = 0; 1564 size_t startoff; 1565 1566 KASSERT((src->scrub || dst->scrub), 1567 ("%s: src->scrub && dst->scrub!", __func__)); 1568 1569 /* 1570 * Enforce the minimum TTL seen for this connection. Negate a common 1571 * technique to evade an intrusion detection system and confuse 1572 * firewall state code. 1573 */ 1574 switch (pd->af) { 1575 #ifdef INET 1576 case AF_INET: { 1577 if (src->scrub) { 1578 struct ip *h = mtod(m, struct ip *); 1579 if (h->ip_ttl > src->scrub->pfss_ttl) 1580 src->scrub->pfss_ttl = h->ip_ttl; 1581 h->ip_ttl = src->scrub->pfss_ttl; 1582 } 1583 break; 1584 } 1585 #endif /* INET */ 1586 #ifdef INET6 1587 case AF_INET6: { 1588 if (src->scrub) { 1589 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1590 if (h->ip6_hlim > src->scrub->pfss_ttl) 1591 src->scrub->pfss_ttl = h->ip6_hlim; 1592 h->ip6_hlim = src->scrub->pfss_ttl; 1593 } 1594 break; 1595 } 1596 #endif /* INET6 */ 1597 } 1598 1599 if (th->th_off > (sizeof(struct tcphdr) >> 2) && 1600 ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) || 1601 (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) && 1602 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1603 /* Diddle with TCP options */ 1604 int hlen; 1605 opt = hdr + sizeof(struct tcphdr); 1606 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1607 while (hlen >= TCPOLEN_TIMESTAMP) { 1608 startoff = opt - (hdr + sizeof(struct tcphdr)); 1609 switch (*opt) { 1610 case TCPOPT_EOL: /* FALLTHROUGH */ 1611 case TCPOPT_NOP: 1612 opt++; 1613 hlen--; 1614 break; 1615 case TCPOPT_TIMESTAMP: 1616 /* Modulate the timestamps. Can be used for 1617 * NAT detection, OS uptime determination or 1618 * reboot detection. 1619 */ 1620 1621 if (got_ts) { 1622 /* Huh? Multiple timestamps!? */ 1623 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1624 DPFPRINTF(("multiple TS??\n")); 1625 pf_print_state(state); 1626 printf("\n"); 1627 } 1628 REASON_SET(reason, PFRES_TS); 1629 return (PF_DROP); 1630 } 1631 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1632 memcpy(&tsval, &opt[2], 1633 sizeof(u_int32_t)); 1634 if (tsval && src->scrub && 1635 (src->scrub->pfss_flags & 1636 PFSS_TIMESTAMP)) { 1637 tsval = ntohl(tsval); 1638 pf_patch_32_unaligned(m, 1639 &th->th_sum, 1640 &opt[2], 1641 htonl(tsval + 1642 src->scrub->pfss_ts_mod), 1643 PF_ALGNMNT(startoff), 1644 0); 1645 copyback = 1; 1646 } 1647 1648 /* Modulate TS reply iff valid (!0) */ 1649 memcpy(&tsecr, &opt[6], 1650 sizeof(u_int32_t)); 1651 if (tsecr && dst->scrub && 1652 (dst->scrub->pfss_flags & 1653 PFSS_TIMESTAMP)) { 1654 tsecr = ntohl(tsecr) 1655 - dst->scrub->pfss_ts_mod; 1656 pf_patch_32_unaligned(m, 1657 &th->th_sum, 1658 &opt[6], 1659 htonl(tsecr), 1660 PF_ALGNMNT(startoff), 1661 0); 1662 copyback = 1; 1663 } 1664 got_ts = 1; 1665 } 1666 /* FALLTHROUGH */ 1667 default: 1668 hlen -= MAX(opt[1], 2); 1669 opt += MAX(opt[1], 2); 1670 break; 1671 } 1672 } 1673 if (copyback) { 1674 /* Copyback the options, caller copys back header */ 1675 *writeback = 1; 1676 m_copyback(m, off + sizeof(struct tcphdr), 1677 (th->th_off << 2) - sizeof(struct tcphdr), hdr + 1678 sizeof(struct tcphdr)); 1679 } 1680 } 1681 1682 /* 1683 * Must invalidate PAWS checks on connections idle for too long. 1684 * The fastest allowed timestamp clock is 1ms. That turns out to 1685 * be about 24 days before it wraps. XXX Right now our lowerbound 1686 * TS echo check only works for the first 12 days of a connection 1687 * when the TS has exhausted half its 32bit space 1688 */ 1689 #define TS_MAX_IDLE (24*24*60*60) 1690 #define TS_MAX_CONN (12*24*60*60) /* XXX remove when better tsecr check */ 1691 1692 getmicrouptime(&uptime); 1693 if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) && 1694 (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE || 1695 time_uptime - state->creation > TS_MAX_CONN)) { 1696 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1697 DPFPRINTF(("src idled out of PAWS\n")); 1698 pf_print_state(state); 1699 printf("\n"); 1700 } 1701 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS) 1702 | PFSS_PAWS_IDLED; 1703 } 1704 if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) && 1705 uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) { 1706 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1707 DPFPRINTF(("dst idled out of PAWS\n")); 1708 pf_print_state(state); 1709 printf("\n"); 1710 } 1711 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS) 1712 | PFSS_PAWS_IDLED; 1713 } 1714 1715 if (got_ts && src->scrub && dst->scrub && 1716 (src->scrub->pfss_flags & PFSS_PAWS) && 1717 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1718 /* Validate that the timestamps are "in-window". 1719 * RFC1323 describes TCP Timestamp options that allow 1720 * measurement of RTT (round trip time) and PAWS 1721 * (protection against wrapped sequence numbers). PAWS 1722 * gives us a set of rules for rejecting packets on 1723 * long fat pipes (packets that were somehow delayed 1724 * in transit longer than the time it took to send the 1725 * full TCP sequence space of 4Gb). We can use these 1726 * rules and infer a few others that will let us treat 1727 * the 32bit timestamp and the 32bit echoed timestamp 1728 * as sequence numbers to prevent a blind attacker from 1729 * inserting packets into a connection. 1730 * 1731 * RFC1323 tells us: 1732 * - The timestamp on this packet must be greater than 1733 * or equal to the last value echoed by the other 1734 * endpoint. The RFC says those will be discarded 1735 * since it is a dup that has already been acked. 1736 * This gives us a lowerbound on the timestamp. 1737 * timestamp >= other last echoed timestamp 1738 * - The timestamp will be less than or equal to 1739 * the last timestamp plus the time between the 1740 * last packet and now. The RFC defines the max 1741 * clock rate as 1ms. We will allow clocks to be 1742 * up to 10% fast and will allow a total difference 1743 * or 30 seconds due to a route change. And this 1744 * gives us an upperbound on the timestamp. 1745 * timestamp <= last timestamp + max ticks 1746 * We have to be careful here. Windows will send an 1747 * initial timestamp of zero and then initialize it 1748 * to a random value after the 3whs; presumably to 1749 * avoid a DoS by having to call an expensive RNG 1750 * during a SYN flood. Proof MS has at least one 1751 * good security geek. 1752 * 1753 * - The TCP timestamp option must also echo the other 1754 * endpoints timestamp. The timestamp echoed is the 1755 * one carried on the earliest unacknowledged segment 1756 * on the left edge of the sequence window. The RFC 1757 * states that the host will reject any echoed 1758 * timestamps that were larger than any ever sent. 1759 * This gives us an upperbound on the TS echo. 1760 * tescr <= largest_tsval 1761 * - The lowerbound on the TS echo is a little more 1762 * tricky to determine. The other endpoint's echoed 1763 * values will not decrease. But there may be 1764 * network conditions that re-order packets and 1765 * cause our view of them to decrease. For now the 1766 * only lowerbound we can safely determine is that 1767 * the TS echo will never be less than the original 1768 * TS. XXX There is probably a better lowerbound. 1769 * Remove TS_MAX_CONN with better lowerbound check. 1770 * tescr >= other original TS 1771 * 1772 * It is also important to note that the fastest 1773 * timestamp clock of 1ms will wrap its 32bit space in 1774 * 24 days. So we just disable TS checking after 24 1775 * days of idle time. We actually must use a 12d 1776 * connection limit until we can come up with a better 1777 * lowerbound to the TS echo check. 1778 */ 1779 struct timeval delta_ts; 1780 int ts_fudge; 1781 1782 /* 1783 * PFTM_TS_DIFF is how many seconds of leeway to allow 1784 * a host's timestamp. This can happen if the previous 1785 * packet got delayed in transit for much longer than 1786 * this packet. 1787 */ 1788 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0) 1789 ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF]; 1790 1791 /* Calculate max ticks since the last timestamp */ 1792 #define TS_MAXFREQ 1100 /* RFC max TS freq of 1Khz + 10% skew */ 1793 #define TS_MICROSECS 1000000 /* microseconds per second */ 1794 delta_ts = uptime; 1795 timevalsub(&delta_ts, &src->scrub->pfss_last); 1796 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ; 1797 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ); 1798 1799 if ((src->state >= TCPS_ESTABLISHED && 1800 dst->state >= TCPS_ESTABLISHED) && 1801 (SEQ_LT(tsval, dst->scrub->pfss_tsecr) || 1802 SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) || 1803 (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) || 1804 SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) { 1805 /* Bad RFC1323 implementation or an insertion attack. 1806 * 1807 * - Solaris 2.6 and 2.7 are known to send another ACK 1808 * after the FIN,FIN|ACK,ACK closing that carries 1809 * an old timestamp. 1810 */ 1811 1812 DPFPRINTF(("Timestamp failed %c%c%c%c\n", 1813 SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ', 1814 SEQ_GT(tsval, src->scrub->pfss_tsval + 1815 tsval_from_last) ? '1' : ' ', 1816 SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ', 1817 SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' ')); 1818 DPFPRINTF((" tsval: %u tsecr: %u +ticks: %u " 1819 "idle: %jus %lums\n", 1820 tsval, tsecr, tsval_from_last, 1821 (uintmax_t)delta_ts.tv_sec, 1822 delta_ts.tv_usec / 1000)); 1823 DPFPRINTF((" src->tsval: %u tsecr: %u\n", 1824 src->scrub->pfss_tsval, src->scrub->pfss_tsecr)); 1825 DPFPRINTF((" dst->tsval: %u tsecr: %u tsval0: %u" 1826 "\n", dst->scrub->pfss_tsval, 1827 dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0)); 1828 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1829 pf_print_state(state); 1830 pf_print_flags(th->th_flags); 1831 printf("\n"); 1832 } 1833 REASON_SET(reason, PFRES_TS); 1834 return (PF_DROP); 1835 } 1836 1837 /* XXX I'd really like to require tsecr but it's optional */ 1838 1839 } else if (!got_ts && (th->th_flags & TH_RST) == 0 && 1840 ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED) 1841 || pd->p_len > 0 || (th->th_flags & TH_SYN)) && 1842 src->scrub && dst->scrub && 1843 (src->scrub->pfss_flags & PFSS_PAWS) && 1844 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1845 /* Didn't send a timestamp. Timestamps aren't really useful 1846 * when: 1847 * - connection opening or closing (often not even sent). 1848 * but we must not let an attacker to put a FIN on a 1849 * data packet to sneak it through our ESTABLISHED check. 1850 * - on a TCP reset. RFC suggests not even looking at TS. 1851 * - on an empty ACK. The TS will not be echoed so it will 1852 * probably not help keep the RTT calculation in sync and 1853 * there isn't as much danger when the sequence numbers 1854 * got wrapped. So some stacks don't include TS on empty 1855 * ACKs :-( 1856 * 1857 * To minimize the disruption to mostly RFC1323 conformant 1858 * stacks, we will only require timestamps on data packets. 1859 * 1860 * And what do ya know, we cannot require timestamps on data 1861 * packets. There appear to be devices that do legitimate 1862 * TCP connection hijacking. There are HTTP devices that allow 1863 * a 3whs (with timestamps) and then buffer the HTTP request. 1864 * If the intermediate device has the HTTP response cache, it 1865 * will spoof the response but not bother timestamping its 1866 * packets. So we can look for the presence of a timestamp in 1867 * the first data packet and if there, require it in all future 1868 * packets. 1869 */ 1870 1871 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) { 1872 /* 1873 * Hey! Someone tried to sneak a packet in. Or the 1874 * stack changed its RFC1323 behavior?!?! 1875 */ 1876 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1877 DPFPRINTF(("Did not receive expected RFC1323 " 1878 "timestamp\n")); 1879 pf_print_state(state); 1880 pf_print_flags(th->th_flags); 1881 printf("\n"); 1882 } 1883 REASON_SET(reason, PFRES_TS); 1884 return (PF_DROP); 1885 } 1886 } 1887 1888 /* 1889 * We will note if a host sends his data packets with or without 1890 * timestamps. And require all data packets to contain a timestamp 1891 * if the first does. PAWS implicitly requires that all data packets be 1892 * timestamped. But I think there are middle-man devices that hijack 1893 * TCP streams immediately after the 3whs and don't timestamp their 1894 * packets (seen in a WWW accelerator or cache). 1895 */ 1896 if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags & 1897 (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) { 1898 if (got_ts) 1899 src->scrub->pfss_flags |= PFSS_DATA_TS; 1900 else { 1901 src->scrub->pfss_flags |= PFSS_DATA_NOTS; 1902 if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub && 1903 (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) { 1904 /* Don't warn if other host rejected RFC1323 */ 1905 DPFPRINTF(("Broken RFC1323 stack did not " 1906 "timestamp data packet. Disabled PAWS " 1907 "security.\n")); 1908 pf_print_state(state); 1909 pf_print_flags(th->th_flags); 1910 printf("\n"); 1911 } 1912 } 1913 } 1914 1915 /* 1916 * Update PAWS values 1917 */ 1918 if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags & 1919 (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) { 1920 getmicrouptime(&src->scrub->pfss_last); 1921 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) || 1922 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 1923 src->scrub->pfss_tsval = tsval; 1924 1925 if (tsecr) { 1926 if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) || 1927 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 1928 src->scrub->pfss_tsecr = tsecr; 1929 1930 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 && 1931 (SEQ_LT(tsval, src->scrub->pfss_tsval0) || 1932 src->scrub->pfss_tsval0 == 0)) { 1933 /* tsval0 MUST be the lowest timestamp */ 1934 src->scrub->pfss_tsval0 = tsval; 1935 } 1936 1937 /* Only fully initialized after a TS gets echoed */ 1938 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0) 1939 src->scrub->pfss_flags |= PFSS_PAWS; 1940 } 1941 } 1942 1943 /* I have a dream.... TCP segment reassembly.... */ 1944 return (0); 1945 } 1946 1947 static int 1948 pf_normalize_tcpopt(struct pf_krule *r, struct mbuf *m, struct tcphdr *th, 1949 int off, sa_family_t af) 1950 { 1951 u_int16_t *mss; 1952 int thoff; 1953 int opt, cnt, optlen = 0; 1954 int rewrite = 0; 1955 u_char opts[TCP_MAXOLEN]; 1956 u_char *optp = opts; 1957 size_t startoff; 1958 1959 thoff = th->th_off << 2; 1960 cnt = thoff - sizeof(struct tcphdr); 1961 1962 if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt, 1963 NULL, NULL, af)) 1964 return (rewrite); 1965 1966 for (; cnt > 0; cnt -= optlen, optp += optlen) { 1967 startoff = optp - opts; 1968 opt = optp[0]; 1969 if (opt == TCPOPT_EOL) 1970 break; 1971 if (opt == TCPOPT_NOP) 1972 optlen = 1; 1973 else { 1974 if (cnt < 2) 1975 break; 1976 optlen = optp[1]; 1977 if (optlen < 2 || optlen > cnt) 1978 break; 1979 } 1980 switch (opt) { 1981 case TCPOPT_MAXSEG: 1982 mss = (u_int16_t *)(optp + 2); 1983 if ((ntohs(*mss)) > r->max_mss) { 1984 pf_patch_16_unaligned(m, 1985 &th->th_sum, 1986 mss, htons(r->max_mss), 1987 PF_ALGNMNT(startoff), 1988 0); 1989 rewrite = 1; 1990 } 1991 break; 1992 default: 1993 break; 1994 } 1995 } 1996 1997 if (rewrite) 1998 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts); 1999 2000 return (rewrite); 2001 } 2002 2003 #ifdef INET 2004 static void 2005 pf_scrub_ip(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos) 2006 { 2007 struct mbuf *m = *m0; 2008 struct ip *h = mtod(m, struct ip *); 2009 2010 /* Clear IP_DF if no-df was requested */ 2011 if (flags & PFRULE_NODF && h->ip_off & htons(IP_DF)) { 2012 u_int16_t ip_off = h->ip_off; 2013 2014 h->ip_off &= htons(~IP_DF); 2015 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 2016 } 2017 2018 /* Enforce a minimum ttl, may cause endless packet loops */ 2019 if (min_ttl && h->ip_ttl < min_ttl) { 2020 u_int16_t ip_ttl = h->ip_ttl; 2021 2022 h->ip_ttl = min_ttl; 2023 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0); 2024 } 2025 2026 /* Enforce tos */ 2027 if (flags & PFRULE_SET_TOS) { 2028 u_int16_t ov, nv; 2029 2030 ov = *(u_int16_t *)h; 2031 h->ip_tos = tos | (h->ip_tos & IPTOS_ECN_MASK); 2032 nv = *(u_int16_t *)h; 2033 2034 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0); 2035 } 2036 2037 /* random-id, but not for fragments */ 2038 if (flags & PFRULE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) { 2039 uint16_t ip_id = h->ip_id; 2040 2041 ip_fillid(h); 2042 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0); 2043 } 2044 } 2045 #endif /* INET */ 2046 2047 #ifdef INET6 2048 static void 2049 pf_scrub_ip6(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos) 2050 { 2051 struct mbuf *m = *m0; 2052 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 2053 2054 /* Enforce a minimum ttl, may cause endless packet loops */ 2055 if (min_ttl && h->ip6_hlim < min_ttl) 2056 h->ip6_hlim = min_ttl; 2057 2058 /* Enforce tos. Set traffic class bits */ 2059 if (flags & PFRULE_SET_TOS) { 2060 h->ip6_flow &= IPV6_FLOWLABEL_MASK | IPV6_VERSION_MASK; 2061 h->ip6_flow |= htonl((tos | IPV6_ECN(h)) << 20); 2062 } 2063 } 2064 #endif 2065