1 /*- 2 * Copyright 2001 Niels Provos <provos@citi.umich.edu> 3 * Copyright 2011 Alexander Bluhm <bluhm@openbsd.org> 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 * $OpenBSD: pf_norm.c,v 1.114 2009/01/29 14:11:45 henning Exp $ 27 */ 28 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 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/rwlock.h> 43 #include <sys/socket.h> 44 45 #include <net/if.h> 46 #include <net/vnet.h> 47 #include <net/pfvar.h> 48 #include <net/if_pflog.h> 49 50 #include <netinet/in.h> 51 #include <netinet/ip.h> 52 #include <netinet/ip_var.h> 53 #include <netinet6/ip6_var.h> 54 #include <netinet/tcp.h> 55 #include <netinet/tcp_fsm.h> 56 #include <netinet/tcp_seq.h> 57 58 #ifdef INET6 59 #include <netinet/ip6.h> 60 #endif /* INET6 */ 61 62 struct pf_frent { 63 TAILQ_ENTRY(pf_frent) fr_next; 64 struct mbuf *fe_m; 65 uint16_t fe_hdrlen; /* ipv4 header lenght with ip options 66 ipv6, extension, fragment header */ 67 uint16_t fe_extoff; /* last extension header offset or 0 */ 68 uint16_t fe_len; /* fragment length */ 69 uint16_t fe_off; /* fragment offset */ 70 uint16_t fe_mff; /* more fragment flag */ 71 }; 72 73 struct pf_fragment_cmp { 74 struct pf_addr frc_src; 75 struct pf_addr frc_dst; 76 uint32_t frc_id; 77 sa_family_t frc_af; 78 uint8_t frc_proto; 79 }; 80 81 struct pf_fragment { 82 struct pf_fragment_cmp fr_key; 83 #define fr_src fr_key.frc_src 84 #define fr_dst fr_key.frc_dst 85 #define fr_id fr_key.frc_id 86 #define fr_af fr_key.frc_af 87 #define fr_proto fr_key.frc_proto 88 89 RB_ENTRY(pf_fragment) fr_entry; 90 TAILQ_ENTRY(pf_fragment) frag_next; 91 uint8_t fr_flags; /* status flags */ 92 #define PFFRAG_SEENLAST 0x0001 /* Seen the last fragment for this */ 93 #define PFFRAG_NOBUFFER 0x0002 /* Non-buffering fragment cache */ 94 #define PFFRAG_DROP 0x0004 /* Drop all fragments */ 95 #define BUFFER_FRAGMENTS(fr) (!((fr)->fr_flags & PFFRAG_NOBUFFER)) 96 uint16_t fr_max; /* fragment data max */ 97 uint32_t fr_timeout; 98 uint16_t fr_maxlen; /* maximum length of single fragment */ 99 TAILQ_HEAD(pf_fragq, pf_frent) fr_queue; 100 }; 101 102 struct pf_fragment_tag { 103 uint16_t ft_hdrlen; /* header length of reassembled pkt */ 104 uint16_t ft_extoff; /* last extension header offset or 0 */ 105 uint16_t ft_maxlen; /* maximum fragment payload length */ 106 uint32_t ft_id; /* fragment id */ 107 }; 108 109 static struct mtx pf_frag_mtx; 110 MTX_SYSINIT(pf_frag_mtx, &pf_frag_mtx, "pf fragments", MTX_DEF); 111 #define PF_FRAG_LOCK() mtx_lock(&pf_frag_mtx) 112 #define PF_FRAG_UNLOCK() mtx_unlock(&pf_frag_mtx) 113 #define PF_FRAG_ASSERT() mtx_assert(&pf_frag_mtx, MA_OWNED) 114 115 VNET_DEFINE(uma_zone_t, pf_state_scrub_z); /* XXX: shared with pfsync */ 116 117 static VNET_DEFINE(uma_zone_t, pf_frent_z); 118 #define V_pf_frent_z VNET(pf_frent_z) 119 static VNET_DEFINE(uma_zone_t, pf_frag_z); 120 #define V_pf_frag_z VNET(pf_frag_z) 121 122 TAILQ_HEAD(pf_fragqueue, pf_fragment); 123 TAILQ_HEAD(pf_cachequeue, pf_fragment); 124 static VNET_DEFINE(struct pf_fragqueue, pf_fragqueue); 125 #define V_pf_fragqueue VNET(pf_fragqueue) 126 static VNET_DEFINE(struct pf_cachequeue, pf_cachequeue); 127 #define V_pf_cachequeue VNET(pf_cachequeue) 128 RB_HEAD(pf_frag_tree, pf_fragment); 129 static VNET_DEFINE(struct pf_frag_tree, pf_frag_tree); 130 #define V_pf_frag_tree VNET(pf_frag_tree) 131 static VNET_DEFINE(struct pf_frag_tree, pf_cache_tree); 132 #define V_pf_cache_tree VNET(pf_cache_tree) 133 static int pf_frag_compare(struct pf_fragment *, 134 struct pf_fragment *); 135 static RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 136 static RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 137 138 static void pf_flush_fragments(void); 139 static void pf_free_fragment(struct pf_fragment *); 140 static void pf_remove_fragment(struct pf_fragment *); 141 static int pf_normalize_tcpopt(struct pf_rule *, struct mbuf *, 142 struct tcphdr *, int, sa_family_t); 143 static struct pf_frent *pf_create_fragment(u_short *); 144 static struct pf_fragment *pf_find_fragment(struct pf_fragment_cmp *key, 145 struct pf_frag_tree *tree); 146 static struct pf_fragment *pf_fillup_fragment(struct pf_fragment_cmp *, 147 struct pf_frent *, u_short *); 148 static int pf_isfull_fragment(struct pf_fragment *); 149 static struct mbuf *pf_join_fragment(struct pf_fragment *); 150 #ifdef INET 151 static void pf_scrub_ip(struct mbuf **, uint32_t, uint8_t, uint8_t); 152 static int pf_reassemble(struct mbuf **, struct ip *, int, u_short *); 153 static struct mbuf *pf_fragcache(struct mbuf **, struct ip*, 154 struct pf_fragment **, int, int, int *); 155 #endif /* INET */ 156 #ifdef INET6 157 static int pf_reassemble6(struct mbuf **, struct ip6_hdr *, 158 struct ip6_frag *, uint16_t, uint16_t, u_short *); 159 static void pf_scrub_ip6(struct mbuf **, uint8_t); 160 #endif /* INET6 */ 161 162 #define DPFPRINTF(x) do { \ 163 if (V_pf_status.debug >= PF_DEBUG_MISC) { \ 164 printf("%s: ", __func__); \ 165 printf x ; \ 166 } \ 167 } while(0) 168 169 #ifdef INET 170 static void 171 pf_ip2key(struct ip *ip, int dir, struct pf_fragment_cmp *key) 172 { 173 174 key->frc_src.v4 = ip->ip_src; 175 key->frc_dst.v4 = ip->ip_dst; 176 key->frc_af = AF_INET; 177 key->frc_proto = ip->ip_p; 178 key->frc_id = ip->ip_id; 179 } 180 #endif /* INET */ 181 182 void 183 pf_normalize_init(void) 184 { 185 186 V_pf_frag_z = uma_zcreate("pf frags", sizeof(struct pf_fragment), 187 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 188 V_pf_frent_z = uma_zcreate("pf frag entries", sizeof(struct pf_frent), 189 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 190 V_pf_state_scrub_z = uma_zcreate("pf state scrubs", 191 sizeof(struct pf_state_scrub), NULL, NULL, NULL, NULL, 192 UMA_ALIGN_PTR, 0); 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 TAILQ_INIT(&V_pf_cachequeue); 201 } 202 203 void 204 pf_normalize_cleanup(void) 205 { 206 207 uma_zdestroy(V_pf_state_scrub_z); 208 uma_zdestroy(V_pf_frent_z); 209 uma_zdestroy(V_pf_frag_z); 210 } 211 212 static int 213 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b) 214 { 215 int diff; 216 217 if ((diff = a->fr_id - b->fr_id) != 0) 218 return (diff); 219 if ((diff = a->fr_proto - b->fr_proto) != 0) 220 return (diff); 221 if ((diff = a->fr_af - b->fr_af) != 0) 222 return (diff); 223 if ((diff = pf_addr_cmp(&a->fr_src, &b->fr_src, a->fr_af)) != 0) 224 return (diff); 225 if ((diff = pf_addr_cmp(&a->fr_dst, &b->fr_dst, a->fr_af)) != 0) 226 return (diff); 227 return (0); 228 } 229 230 void 231 pf_purge_expired_fragments(void) 232 { 233 struct pf_fragment *frag; 234 u_int32_t expire = time_uptime - 235 V_pf_default_rule.timeout[PFTM_FRAG]; 236 237 PF_FRAG_LOCK(); 238 while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) { 239 KASSERT((BUFFER_FRAGMENTS(frag)), 240 ("BUFFER_FRAGMENTS(frag) == 0: %s", __FUNCTION__)); 241 if (frag->fr_timeout > expire) 242 break; 243 244 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); 245 pf_free_fragment(frag); 246 } 247 248 while ((frag = TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue)) != NULL) { 249 KASSERT((!BUFFER_FRAGMENTS(frag)), 250 ("BUFFER_FRAGMENTS(frag) != 0: %s", __FUNCTION__)); 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 KASSERT((TAILQ_EMPTY(&V_pf_cachequeue) || 257 TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue) != frag), 258 ("!(TAILQ_EMPTY() || TAILQ_LAST() == farg): %s", 259 __FUNCTION__)); 260 } 261 PF_FRAG_UNLOCK(); 262 } 263 264 /* 265 * Try to flush old fragments to make space for new ones 266 */ 267 static void 268 pf_flush_fragments(void) 269 { 270 struct pf_fragment *frag, *cache; 271 int goal; 272 273 PF_FRAG_ASSERT(); 274 275 goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10; 276 DPFPRINTF(("trying to free %d frag entriess\n", goal)); 277 while (goal < uma_zone_get_cur(V_pf_frent_z)) { 278 frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue); 279 if (frag) 280 pf_free_fragment(frag); 281 cache = TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue); 282 if (cache) 283 pf_free_fragment(cache); 284 if (frag == NULL && cache == NULL) 285 break; 286 } 287 } 288 289 /* Frees the fragments and all associated entries */ 290 static void 291 pf_free_fragment(struct pf_fragment *frag) 292 { 293 struct pf_frent *frent; 294 295 PF_FRAG_ASSERT(); 296 297 /* Free all fragments */ 298 if (BUFFER_FRAGMENTS(frag)) { 299 for (frent = TAILQ_FIRST(&frag->fr_queue); frent; 300 frent = TAILQ_FIRST(&frag->fr_queue)) { 301 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 302 303 m_freem(frent->fe_m); 304 uma_zfree(V_pf_frent_z, frent); 305 } 306 } else { 307 for (frent = TAILQ_FIRST(&frag->fr_queue); frent; 308 frent = TAILQ_FIRST(&frag->fr_queue)) { 309 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 310 311 KASSERT((TAILQ_EMPTY(&frag->fr_queue) || 312 TAILQ_FIRST(&frag->fr_queue)->fe_off > 313 frent->fe_len), 314 ("! (TAILQ_EMPTY() || TAILQ_FIRST()->fe_off >" 315 " frent->fe_len): %s", __func__)); 316 317 uma_zfree(V_pf_frent_z, frent); 318 } 319 } 320 321 pf_remove_fragment(frag); 322 } 323 324 static struct pf_fragment * 325 pf_find_fragment(struct pf_fragment_cmp *key, struct pf_frag_tree *tree) 326 { 327 struct pf_fragment *frag; 328 329 PF_FRAG_ASSERT(); 330 331 frag = RB_FIND(pf_frag_tree, tree, (struct pf_fragment *)key); 332 if (frag != NULL) { 333 /* XXX Are we sure we want to update the timeout? */ 334 frag->fr_timeout = time_uptime; 335 if (BUFFER_FRAGMENTS(frag)) { 336 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next); 337 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next); 338 } else { 339 TAILQ_REMOVE(&V_pf_cachequeue, frag, frag_next); 340 TAILQ_INSERT_HEAD(&V_pf_cachequeue, frag, frag_next); 341 } 342 } 343 344 return (frag); 345 } 346 347 /* Removes a fragment from the fragment queue and frees the fragment */ 348 static void 349 pf_remove_fragment(struct pf_fragment *frag) 350 { 351 352 PF_FRAG_ASSERT(); 353 354 if (BUFFER_FRAGMENTS(frag)) { 355 RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag); 356 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next); 357 uma_zfree(V_pf_frag_z, frag); 358 } else { 359 RB_REMOVE(pf_frag_tree, &V_pf_cache_tree, frag); 360 TAILQ_REMOVE(&V_pf_cachequeue, frag, frag_next); 361 uma_zfree(V_pf_frag_z, frag); 362 } 363 } 364 365 static struct pf_frent * 366 pf_create_fragment(u_short *reason) 367 { 368 struct pf_frent *frent; 369 370 PF_FRAG_ASSERT(); 371 372 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT); 373 if (frent == NULL) { 374 pf_flush_fragments(); 375 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT); 376 if (frent == NULL) { 377 REASON_SET(reason, PFRES_MEMORY); 378 return (NULL); 379 } 380 } 381 382 return (frent); 383 } 384 385 static struct pf_fragment * 386 pf_fillup_fragment(struct pf_fragment_cmp *key, struct pf_frent *frent, 387 u_short *reason) 388 { 389 struct pf_frent *after, *next, *prev; 390 struct pf_fragment *frag; 391 uint16_t total; 392 393 PF_FRAG_ASSERT(); 394 395 /* No empty fragments. */ 396 if (frent->fe_len == 0) { 397 DPFPRINTF(("bad fragment: len 0")); 398 goto bad_fragment; 399 } 400 401 /* All fragments are 8 byte aligned. */ 402 if (frent->fe_mff && (frent->fe_len & 0x7)) { 403 DPFPRINTF(("bad fragment: mff and len %d", frent->fe_len)); 404 goto bad_fragment; 405 } 406 407 /* Respect maximum length, IP_MAXPACKET == IPV6_MAXPACKET. */ 408 if (frent->fe_off + frent->fe_len > IP_MAXPACKET) { 409 DPFPRINTF(("bad fragment: max packet %d", 410 frent->fe_off + frent->fe_len)); 411 goto bad_fragment; 412 } 413 414 DPFPRINTF((key->frc_af == AF_INET ? 415 "reass frag %d @ %d-%d" : "reass frag %#08x @ %d-%d", 416 key->frc_id, frent->fe_off, frent->fe_off + frent->fe_len)); 417 418 /* Fully buffer all of the fragments in this fragment queue. */ 419 frag = pf_find_fragment(key, &V_pf_frag_tree); 420 421 /* Create a new reassembly queue for this packet. */ 422 if (frag == NULL) { 423 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 424 if (frag == NULL) { 425 pf_flush_fragments(); 426 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 427 if (frag == NULL) { 428 REASON_SET(reason, PFRES_MEMORY); 429 goto drop_fragment; 430 } 431 } 432 433 *(struct pf_fragment_cmp *)frag = *key; 434 frag->fr_flags = 0; 435 frag->fr_timeout = time_second; 436 frag->fr_maxlen = frent->fe_len; 437 TAILQ_INIT(&frag->fr_queue); 438 439 RB_INSERT(pf_frag_tree, &V_pf_frag_tree, frag); 440 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next); 441 442 /* We do not have a previous fragment. */ 443 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next); 444 445 return (frag); 446 } 447 448 KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue")); 449 450 /* Remember maximum fragment len for refragmentation. */ 451 if (frent->fe_len > frag->fr_maxlen) 452 frag->fr_maxlen = frent->fe_len; 453 454 /* Maximum data we have seen already. */ 455 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 456 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 457 458 /* Non terminal fragments must have more fragments flag. */ 459 if (frent->fe_off + frent->fe_len < total && !frent->fe_mff) 460 goto bad_fragment; 461 462 /* Check if we saw the last fragment already. */ 463 if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) { 464 if (frent->fe_off + frent->fe_len > total || 465 (frent->fe_off + frent->fe_len == total && frent->fe_mff)) 466 goto bad_fragment; 467 } else { 468 if (frent->fe_off + frent->fe_len == total && !frent->fe_mff) 469 goto bad_fragment; 470 } 471 472 /* Find a fragment after the current one. */ 473 prev = NULL; 474 TAILQ_FOREACH(after, &frag->fr_queue, fr_next) { 475 if (after->fe_off > frent->fe_off) 476 break; 477 prev = after; 478 } 479 480 KASSERT(prev != NULL || after != NULL, 481 ("prev != NULL || after != NULL")); 482 483 if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) { 484 uint16_t precut; 485 486 precut = prev->fe_off + prev->fe_len - frent->fe_off; 487 if (precut >= frent->fe_len) 488 goto bad_fragment; 489 DPFPRINTF(("overlap -%d", precut)); 490 m_adj(frent->fe_m, precut); 491 frent->fe_off += precut; 492 frent->fe_len -= precut; 493 } 494 495 for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off; 496 after = next) { 497 uint16_t aftercut; 498 499 aftercut = frent->fe_off + frent->fe_len - after->fe_off; 500 DPFPRINTF(("adjust overlap %d", aftercut)); 501 if (aftercut < after->fe_len) { 502 m_adj(after->fe_m, aftercut); 503 after->fe_off += aftercut; 504 after->fe_len -= aftercut; 505 break; 506 } 507 508 /* This fragment is completely overlapped, lose it. */ 509 next = TAILQ_NEXT(after, fr_next); 510 m_freem(after->fe_m); 511 TAILQ_REMOVE(&frag->fr_queue, after, fr_next); 512 uma_zfree(V_pf_frent_z, after); 513 } 514 515 if (prev == NULL) 516 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next); 517 else 518 TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next); 519 520 return (frag); 521 522 bad_fragment: 523 REASON_SET(reason, PFRES_FRAG); 524 drop_fragment: 525 uma_zfree(V_pf_frent_z, frent); 526 return (NULL); 527 } 528 529 static int 530 pf_isfull_fragment(struct pf_fragment *frag) 531 { 532 struct pf_frent *frent, *next; 533 uint16_t off, total; 534 535 /* Check if we are completely reassembled */ 536 if (TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) 537 return (0); 538 539 /* Maximum data we have seen already */ 540 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 541 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 542 543 /* Check if we have all the data */ 544 off = 0; 545 for (frent = TAILQ_FIRST(&frag->fr_queue); frent; frent = next) { 546 next = TAILQ_NEXT(frent, fr_next); 547 548 off += frent->fe_len; 549 if (off < total && (next == NULL || next->fe_off != off)) { 550 DPFPRINTF(("missing fragment at %d, next %d, total %d", 551 off, next == NULL ? -1 : next->fe_off, total)); 552 return (0); 553 } 554 } 555 DPFPRINTF(("%d < %d?", off, total)); 556 if (off < total) 557 return (0); 558 KASSERT(off == total, ("off == total")); 559 560 return (1); 561 } 562 563 static struct mbuf * 564 pf_join_fragment(struct pf_fragment *frag) 565 { 566 struct mbuf *m, *m2; 567 struct pf_frent *frent, *next; 568 569 frent = TAILQ_FIRST(&frag->fr_queue); 570 next = TAILQ_NEXT(frent, fr_next); 571 572 m = frent->fe_m; 573 m_adj(m, (frent->fe_hdrlen + frent->fe_len) - m->m_pkthdr.len); 574 uma_zfree(V_pf_frent_z, frent); 575 for (frent = next; frent != NULL; frent = next) { 576 next = TAILQ_NEXT(frent, fr_next); 577 578 m2 = frent->fe_m; 579 /* Strip off ip header. */ 580 m_adj(m2, frent->fe_hdrlen); 581 /* Strip off any trailing bytes. */ 582 m_adj(m2, frent->fe_len - m2->m_pkthdr.len); 583 584 uma_zfree(V_pf_frent_z, frent); 585 m_cat(m, m2); 586 } 587 588 /* Remove from fragment queue. */ 589 pf_remove_fragment(frag); 590 591 return (m); 592 } 593 594 #ifdef INET 595 static int 596 pf_reassemble(struct mbuf **m0, struct ip *ip, int dir, u_short *reason) 597 { 598 struct mbuf *m = *m0; 599 struct pf_frent *frent; 600 struct pf_fragment *frag; 601 struct pf_fragment_cmp key; 602 uint16_t total, hdrlen; 603 604 /* Get an entry for the fragment queue */ 605 if ((frent = pf_create_fragment(reason)) == NULL) 606 return (PF_DROP); 607 608 frent->fe_m = m; 609 frent->fe_hdrlen = ip->ip_hl << 2; 610 frent->fe_extoff = 0; 611 frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2); 612 frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3; 613 frent->fe_mff = ntohs(ip->ip_off) & IP_MF; 614 615 pf_ip2key(ip, dir, &key); 616 617 if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) 618 return (PF_DROP); 619 620 /* The mbuf is part of the fragment entry, no direct free or access */ 621 m = *m0 = NULL; 622 623 if (!pf_isfull_fragment(frag)) 624 return (PF_PASS); /* drop because *m0 is NULL, no error */ 625 626 /* We have all the data */ 627 frent = TAILQ_FIRST(&frag->fr_queue); 628 KASSERT(frent != NULL, ("frent != NULL")); 629 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 630 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 631 hdrlen = frent->fe_hdrlen; 632 633 m = *m0 = pf_join_fragment(frag); 634 frag = NULL; 635 636 if (m->m_flags & M_PKTHDR) { 637 int plen = 0; 638 for (m = *m0; m; m = m->m_next) 639 plen += m->m_len; 640 m = *m0; 641 m->m_pkthdr.len = plen; 642 } 643 644 ip = mtod(m, struct ip *); 645 ip->ip_len = htons(hdrlen + total); 646 ip->ip_off &= ~(IP_MF|IP_OFFMASK); 647 648 if (hdrlen + total > IP_MAXPACKET) { 649 DPFPRINTF(("drop: too big: %d", total)); 650 ip->ip_len = 0; 651 REASON_SET(reason, PFRES_SHORT); 652 /* PF_DROP requires a valid mbuf *m0 in pf_test() */ 653 return (PF_DROP); 654 } 655 656 DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len))); 657 return (PF_PASS); 658 } 659 #endif /* INET */ 660 661 #ifdef INET6 662 static int 663 pf_reassemble6(struct mbuf **m0, struct ip6_hdr *ip6, struct ip6_frag *fraghdr, 664 uint16_t hdrlen, uint16_t extoff, u_short *reason) 665 { 666 struct mbuf *m = *m0; 667 struct pf_frent *frent; 668 struct pf_fragment *frag; 669 struct pf_fragment_cmp key; 670 struct m_tag *mtag; 671 struct pf_fragment_tag *ftag; 672 int off; 673 uint32_t frag_id; 674 uint16_t total, maxlen; 675 uint8_t proto; 676 677 PF_FRAG_LOCK(); 678 679 /* Get an entry for the fragment queue. */ 680 if ((frent = pf_create_fragment(reason)) == NULL) { 681 PF_FRAG_UNLOCK(); 682 return (PF_DROP); 683 } 684 685 frent->fe_m = m; 686 frent->fe_hdrlen = hdrlen; 687 frent->fe_extoff = extoff; 688 frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen; 689 frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK); 690 frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG; 691 692 key.frc_src.v6 = ip6->ip6_src; 693 key.frc_dst.v6 = ip6->ip6_dst; 694 key.frc_af = AF_INET6; 695 /* Only the first fragment's protocol is relevant. */ 696 key.frc_proto = 0; 697 key.frc_id = fraghdr->ip6f_ident; 698 699 if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) { 700 PF_FRAG_UNLOCK(); 701 return (PF_DROP); 702 } 703 704 /* The mbuf is part of the fragment entry, no direct free or access. */ 705 m = *m0 = NULL; 706 707 if (!pf_isfull_fragment(frag)) { 708 PF_FRAG_UNLOCK(); 709 return (PF_PASS); /* Drop because *m0 is NULL, no error. */ 710 } 711 712 /* We have all the data. */ 713 extoff = frent->fe_extoff; 714 maxlen = frag->fr_maxlen; 715 frag_id = frag->fr_id; 716 frent = TAILQ_FIRST(&frag->fr_queue); 717 KASSERT(frent != NULL, ("frent != NULL")); 718 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 719 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 720 hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag); 721 722 m = *m0 = pf_join_fragment(frag); 723 frag = NULL; 724 725 PF_FRAG_UNLOCK(); 726 727 /* Take protocol from first fragment header. */ 728 m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off); 729 KASSERT(m, ("%s: short mbuf chain", __func__)); 730 proto = *(mtod(m, caddr_t) + off); 731 m = *m0; 732 733 /* Delete frag6 header */ 734 if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0) 735 goto fail; 736 737 if (m->m_flags & M_PKTHDR) { 738 int plen = 0; 739 for (m = *m0; m; m = m->m_next) 740 plen += m->m_len; 741 m = *m0; 742 m->m_pkthdr.len = plen; 743 } 744 745 if ((mtag = m_tag_get(PF_REASSEMBLED, sizeof(struct pf_fragment_tag), 746 M_NOWAIT)) == NULL) 747 goto fail; 748 ftag = (struct pf_fragment_tag *)(mtag + 1); 749 ftag->ft_hdrlen = hdrlen; 750 ftag->ft_extoff = extoff; 751 ftag->ft_maxlen = maxlen; 752 ftag->ft_id = frag_id; 753 m_tag_prepend(m, mtag); 754 755 ip6 = mtod(m, struct ip6_hdr *); 756 ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total); 757 if (extoff) { 758 /* Write protocol into next field of last extension header. */ 759 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt), 760 &off); 761 KASSERT(m, ("%s: short mbuf chain", __func__)); 762 *(mtod(m, char *) + off) = proto; 763 m = *m0; 764 } else 765 ip6->ip6_nxt = proto; 766 767 if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) { 768 DPFPRINTF(("drop: too big: %d", total)); 769 ip6->ip6_plen = 0; 770 REASON_SET(reason, PFRES_SHORT); 771 /* PF_DROP requires a valid mbuf *m0 in pf_test6(). */ 772 return (PF_DROP); 773 } 774 775 DPFPRINTF(("complete: %p(%d)", m, ntohs(ip6->ip6_plen))); 776 return (PF_PASS); 777 778 fail: 779 REASON_SET(reason, PFRES_MEMORY); 780 /* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */ 781 return (PF_DROP); 782 } 783 #endif /* INET6 */ 784 785 #ifdef INET 786 static struct mbuf * 787 pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff, 788 int drop, int *nomem) 789 { 790 struct mbuf *m = *m0; 791 struct pf_frent *frp, *fra, *cur = NULL; 792 int ip_len = ntohs(h->ip_len) - (h->ip_hl << 2); 793 u_int16_t off = ntohs(h->ip_off) << 3; 794 u_int16_t max = ip_len + off; 795 int hosed = 0; 796 797 PF_FRAG_ASSERT(); 798 KASSERT((*frag == NULL || !BUFFER_FRAGMENTS(*frag)), 799 ("!(*frag == NULL || !BUFFER_FRAGMENTS(*frag)): %s", __FUNCTION__)); 800 801 /* Create a new range queue for this packet */ 802 if (*frag == NULL) { 803 *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 804 if (*frag == NULL) { 805 pf_flush_fragments(); 806 *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 807 if (*frag == NULL) 808 goto no_mem; 809 } 810 811 /* Get an entry for the queue */ 812 cur = uma_zalloc(V_pf_frent_z, M_NOWAIT); 813 if (cur == NULL) { 814 uma_zfree(V_pf_frag_z, *frag); 815 *frag = NULL; 816 goto no_mem; 817 } 818 819 (*frag)->fr_flags = PFFRAG_NOBUFFER; 820 (*frag)->fr_max = 0; 821 (*frag)->fr_src.v4 = h->ip_src; 822 (*frag)->fr_dst.v4 = h->ip_dst; 823 (*frag)->fr_af = AF_INET; 824 (*frag)->fr_proto = h->ip_p; 825 (*frag)->fr_id = h->ip_id; 826 (*frag)->fr_timeout = time_uptime; 827 828 cur->fe_off = off; 829 cur->fe_len = max; /* TODO: fe_len = max - off ? */ 830 TAILQ_INIT(&(*frag)->fr_queue); 831 TAILQ_INSERT_HEAD(&(*frag)->fr_queue, cur, fr_next); 832 833 RB_INSERT(pf_frag_tree, &V_pf_cache_tree, *frag); 834 TAILQ_INSERT_HEAD(&V_pf_cachequeue, *frag, frag_next); 835 836 DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max)); 837 838 goto pass; 839 } 840 841 /* 842 * Find a fragment after the current one: 843 * - off contains the real shifted offset. 844 */ 845 frp = NULL; 846 TAILQ_FOREACH(fra, &(*frag)->fr_queue, fr_next) { 847 if (fra->fe_off > off) 848 break; 849 frp = fra; 850 } 851 852 KASSERT((frp != NULL || fra != NULL), 853 ("!(frp != NULL || fra != NULL): %s", __FUNCTION__)); 854 855 if (frp != NULL) { 856 int precut; 857 858 precut = frp->fe_len - off; 859 if (precut >= ip_len) { 860 /* Fragment is entirely a duplicate */ 861 DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n", 862 h->ip_id, frp->fe_off, frp->fe_len, off, max)); 863 goto drop_fragment; 864 } 865 if (precut == 0) { 866 /* They are adjacent. Fixup cache entry */ 867 DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n", 868 h->ip_id, frp->fe_off, frp->fe_len, off, max)); 869 frp->fe_len = max; 870 } else if (precut > 0) { 871 /* The first part of this payload overlaps with a 872 * fragment that has already been passed. 873 * Need to trim off the first part of the payload. 874 * But to do so easily, we need to create another 875 * mbuf to throw the original header into. 876 */ 877 878 DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n", 879 h->ip_id, precut, frp->fe_off, frp->fe_len, off, 880 max)); 881 882 off += precut; 883 max -= precut; 884 /* Update the previous frag to encompass this one */ 885 frp->fe_len = max; 886 887 if (!drop) { 888 /* XXX Optimization opportunity 889 * This is a very heavy way to trim the payload. 890 * we could do it much faster by diddling mbuf 891 * internals but that would be even less legible 892 * than this mbuf magic. For my next trick, 893 * I'll pull a rabbit out of my laptop. 894 */ 895 *m0 = m_dup(m, M_NOWAIT); 896 if (*m0 == NULL) 897 goto no_mem; 898 /* From KAME Project : We have missed this! */ 899 m_adj(*m0, (h->ip_hl << 2) - 900 (*m0)->m_pkthdr.len); 901 902 KASSERT(((*m0)->m_next == NULL), 903 ("(*m0)->m_next != NULL: %s", 904 __FUNCTION__)); 905 m_adj(m, precut + (h->ip_hl << 2)); 906 m_cat(*m0, m); 907 m = *m0; 908 if (m->m_flags & M_PKTHDR) { 909 int plen = 0; 910 struct mbuf *t; 911 for (t = m; t; t = t->m_next) 912 plen += t->m_len; 913 m->m_pkthdr.len = plen; 914 } 915 916 917 h = mtod(m, struct ip *); 918 919 KASSERT(((int)m->m_len == 920 ntohs(h->ip_len) - precut), 921 ("m->m_len != ntohs(h->ip_len) - precut: %s", 922 __FUNCTION__)); 923 h->ip_off = htons(ntohs(h->ip_off) + 924 (precut >> 3)); 925 h->ip_len = htons(ntohs(h->ip_len) - precut); 926 } else { 927 hosed++; 928 } 929 } else { 930 /* There is a gap between fragments */ 931 932 DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n", 933 h->ip_id, -precut, frp->fe_off, frp->fe_len, off, 934 max)); 935 936 cur = uma_zalloc(V_pf_frent_z, M_NOWAIT); 937 if (cur == NULL) 938 goto no_mem; 939 940 cur->fe_off = off; 941 cur->fe_len = max; 942 TAILQ_INSERT_AFTER(&(*frag)->fr_queue, frp, cur, fr_next); 943 } 944 } 945 946 if (fra != NULL) { 947 int aftercut; 948 int merge = 0; 949 950 aftercut = max - fra->fe_off; 951 if (aftercut == 0) { 952 /* Adjacent fragments */ 953 DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n", 954 h->ip_id, off, max, fra->fe_off, fra->fe_len)); 955 fra->fe_off = off; 956 merge = 1; 957 } else if (aftercut > 0) { 958 /* Need to chop off the tail of this fragment */ 959 DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n", 960 h->ip_id, aftercut, off, max, fra->fe_off, 961 fra->fe_len)); 962 fra->fe_off = off; 963 max -= aftercut; 964 965 merge = 1; 966 967 if (!drop) { 968 m_adj(m, -aftercut); 969 if (m->m_flags & M_PKTHDR) { 970 int plen = 0; 971 struct mbuf *t; 972 for (t = m; t; t = t->m_next) 973 plen += t->m_len; 974 m->m_pkthdr.len = plen; 975 } 976 h = mtod(m, struct ip *); 977 KASSERT(((int)m->m_len == ntohs(h->ip_len) - aftercut), 978 ("m->m_len != ntohs(h->ip_len) - aftercut: %s", 979 __FUNCTION__)); 980 h->ip_len = htons(ntohs(h->ip_len) - aftercut); 981 } else { 982 hosed++; 983 } 984 } else if (frp == NULL) { 985 /* There is a gap between fragments */ 986 DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n", 987 h->ip_id, -aftercut, off, max, fra->fe_off, 988 fra->fe_len)); 989 990 cur = uma_zalloc(V_pf_frent_z, M_NOWAIT); 991 if (cur == NULL) 992 goto no_mem; 993 994 cur->fe_off = off; 995 cur->fe_len = max; 996 TAILQ_INSERT_HEAD(&(*frag)->fr_queue, cur, fr_next); 997 } 998 999 1000 /* Need to glue together two separate fragment descriptors */ 1001 if (merge) { 1002 if (cur && fra->fe_off <= cur->fe_len) { 1003 /* Need to merge in a previous 'cur' */ 1004 DPFPRINTF(("fragcache[%d]: adjacent(merge " 1005 "%d-%d) %d-%d (%d-%d)\n", 1006 h->ip_id, cur->fe_off, cur->fe_len, off, 1007 max, fra->fe_off, fra->fe_len)); 1008 fra->fe_off = cur->fe_off; 1009 TAILQ_REMOVE(&(*frag)->fr_queue, cur, fr_next); 1010 uma_zfree(V_pf_frent_z, cur); 1011 cur = NULL; 1012 1013 } else if (frp && fra->fe_off <= frp->fe_len) { 1014 /* Need to merge in a modified 'frp' */ 1015 KASSERT((cur == NULL), ("cur != NULL: %s", 1016 __FUNCTION__)); 1017 DPFPRINTF(("fragcache[%d]: adjacent(merge " 1018 "%d-%d) %d-%d (%d-%d)\n", 1019 h->ip_id, frp->fe_off, frp->fe_len, off, 1020 max, fra->fe_off, fra->fe_len)); 1021 fra->fe_off = frp->fe_off; 1022 TAILQ_REMOVE(&(*frag)->fr_queue, frp, fr_next); 1023 uma_zfree(V_pf_frent_z, frp); 1024 frp = NULL; 1025 1026 } 1027 } 1028 } 1029 1030 if (hosed) { 1031 /* 1032 * We must keep tracking the overall fragment even when 1033 * we're going to drop it anyway so that we know when to 1034 * free the overall descriptor. Thus we drop the frag late. 1035 */ 1036 goto drop_fragment; 1037 } 1038 1039 1040 pass: 1041 /* Update maximum data size */ 1042 if ((*frag)->fr_max < max) 1043 (*frag)->fr_max = max; 1044 1045 /* This is the last segment */ 1046 if (!mff) 1047 (*frag)->fr_flags |= PFFRAG_SEENLAST; 1048 1049 /* Check if we are completely reassembled */ 1050 if (((*frag)->fr_flags & PFFRAG_SEENLAST) && 1051 TAILQ_FIRST(&(*frag)->fr_queue)->fe_off == 0 && 1052 TAILQ_FIRST(&(*frag)->fr_queue)->fe_len == (*frag)->fr_max) { 1053 /* Remove from fragment queue */ 1054 DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id, 1055 (*frag)->fr_max)); 1056 pf_free_fragment(*frag); 1057 *frag = NULL; 1058 } 1059 1060 return (m); 1061 1062 no_mem: 1063 *nomem = 1; 1064 1065 /* Still need to pay attention to !IP_MF */ 1066 if (!mff && *frag != NULL) 1067 (*frag)->fr_flags |= PFFRAG_SEENLAST; 1068 1069 m_freem(m); 1070 return (NULL); 1071 1072 drop_fragment: 1073 1074 /* Still need to pay attention to !IP_MF */ 1075 if (!mff && *frag != NULL) 1076 (*frag)->fr_flags |= PFFRAG_SEENLAST; 1077 1078 if (drop) { 1079 /* This fragment has been deemed bad. Don't reass */ 1080 if (((*frag)->fr_flags & PFFRAG_DROP) == 0) 1081 DPFPRINTF(("fragcache[%d]: dropping overall fragment\n", 1082 h->ip_id)); 1083 (*frag)->fr_flags |= PFFRAG_DROP; 1084 } 1085 1086 m_freem(m); 1087 return (NULL); 1088 } 1089 #endif /* INET */ 1090 1091 #ifdef INET6 1092 int 1093 pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag) 1094 { 1095 struct mbuf *m = *m0, *t; 1096 struct pf_fragment_tag *ftag = (struct pf_fragment_tag *)(mtag + 1); 1097 struct pf_pdesc pd; 1098 uint32_t frag_id; 1099 uint16_t hdrlen, extoff, maxlen; 1100 uint8_t proto; 1101 int error, action; 1102 1103 hdrlen = ftag->ft_hdrlen; 1104 extoff = ftag->ft_extoff; 1105 maxlen = ftag->ft_maxlen; 1106 frag_id = ftag->ft_id; 1107 m_tag_delete(m, mtag); 1108 mtag = NULL; 1109 ftag = NULL; 1110 1111 if (extoff) { 1112 int off; 1113 1114 /* Use protocol from next field of last extension header */ 1115 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt), 1116 &off); 1117 KASSERT((m != NULL), ("pf_refragment6: short mbuf chain")); 1118 proto = *(mtod(m, caddr_t) + off); 1119 *(mtod(m, char *) + off) = IPPROTO_FRAGMENT; 1120 m = *m0; 1121 } else { 1122 struct ip6_hdr *hdr; 1123 1124 hdr = mtod(m, struct ip6_hdr *); 1125 proto = hdr->ip6_nxt; 1126 hdr->ip6_nxt = IPPROTO_FRAGMENT; 1127 } 1128 1129 /* 1130 * Maxlen may be less than 8 if there was only a single 1131 * fragment. As it was fragmented before, add a fragment 1132 * header also for a single fragment. If total or maxlen 1133 * is less than 8, ip6_fragment() will return EMSGSIZE and 1134 * we drop the packet. 1135 */ 1136 error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id); 1137 m = (*m0)->m_nextpkt; 1138 (*m0)->m_nextpkt = NULL; 1139 if (error == 0) { 1140 /* The first mbuf contains the unfragmented packet. */ 1141 m_freem(*m0); 1142 *m0 = NULL; 1143 action = PF_PASS; 1144 } else { 1145 /* Drop expects an mbuf to free. */ 1146 DPFPRINTF(("refragment error %d", error)); 1147 action = PF_DROP; 1148 } 1149 for (t = m; m; m = t) { 1150 t = m->m_nextpkt; 1151 m->m_nextpkt = NULL; 1152 m->m_flags |= M_SKIP_FIREWALL; 1153 memset(&pd, 0, sizeof(pd)); 1154 pd.pf_mtag = pf_find_mtag(m); 1155 if (error == 0) 1156 ip6_forward(m, 0); 1157 else 1158 m_freem(m); 1159 } 1160 1161 return (action); 1162 } 1163 #endif /* INET6 */ 1164 1165 #ifdef INET 1166 int 1167 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason, 1168 struct pf_pdesc *pd) 1169 { 1170 struct mbuf *m = *m0; 1171 struct pf_rule *r; 1172 struct pf_fragment *frag = NULL; 1173 struct pf_fragment_cmp key; 1174 struct ip *h = mtod(m, struct ip *); 1175 int mff = (ntohs(h->ip_off) & IP_MF); 1176 int hlen = h->ip_hl << 2; 1177 u_int16_t fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3; 1178 u_int16_t max; 1179 int ip_len; 1180 int ip_off; 1181 int tag = -1; 1182 int verdict; 1183 1184 PF_RULES_RASSERT(); 1185 1186 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1187 while (r != NULL) { 1188 r->evaluations++; 1189 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1190 r = r->skip[PF_SKIP_IFP].ptr; 1191 else if (r->direction && r->direction != dir) 1192 r = r->skip[PF_SKIP_DIR].ptr; 1193 else if (r->af && r->af != AF_INET) 1194 r = r->skip[PF_SKIP_AF].ptr; 1195 else if (r->proto && r->proto != h->ip_p) 1196 r = r->skip[PF_SKIP_PROTO].ptr; 1197 else if (PF_MISMATCHAW(&r->src.addr, 1198 (struct pf_addr *)&h->ip_src.s_addr, AF_INET, 1199 r->src.neg, kif, M_GETFIB(m))) 1200 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1201 else if (PF_MISMATCHAW(&r->dst.addr, 1202 (struct pf_addr *)&h->ip_dst.s_addr, AF_INET, 1203 r->dst.neg, NULL, M_GETFIB(m))) 1204 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1205 else if (r->match_tag && !pf_match_tag(m, r, &tag, 1206 pd->pf_mtag ? pd->pf_mtag->tag : 0)) 1207 r = TAILQ_NEXT(r, entries); 1208 else 1209 break; 1210 } 1211 1212 if (r == NULL || r->action == PF_NOSCRUB) 1213 return (PF_PASS); 1214 else { 1215 r->packets[dir == PF_OUT]++; 1216 r->bytes[dir == PF_OUT] += pd->tot_len; 1217 } 1218 1219 /* Check for illegal packets */ 1220 if (hlen < (int)sizeof(struct ip)) 1221 goto drop; 1222 1223 if (hlen > ntohs(h->ip_len)) 1224 goto drop; 1225 1226 /* Clear IP_DF if the rule uses the no-df option */ 1227 if (r->rule_flag & PFRULE_NODF && h->ip_off & htons(IP_DF)) { 1228 u_int16_t ip_off = h->ip_off; 1229 1230 h->ip_off &= htons(~IP_DF); 1231 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1232 } 1233 1234 /* We will need other tests here */ 1235 if (!fragoff && !mff) 1236 goto no_fragment; 1237 1238 /* We're dealing with a fragment now. Don't allow fragments 1239 * with IP_DF to enter the cache. If the flag was cleared by 1240 * no-df above, fine. Otherwise drop it. 1241 */ 1242 if (h->ip_off & htons(IP_DF)) { 1243 DPFPRINTF(("IP_DF\n")); 1244 goto bad; 1245 } 1246 1247 ip_len = ntohs(h->ip_len) - hlen; 1248 ip_off = (ntohs(h->ip_off) & IP_OFFMASK) << 3; 1249 1250 /* All fragments are 8 byte aligned */ 1251 if (mff && (ip_len & 0x7)) { 1252 DPFPRINTF(("mff and %d\n", ip_len)); 1253 goto bad; 1254 } 1255 1256 /* Respect maximum length */ 1257 if (fragoff + ip_len > IP_MAXPACKET) { 1258 DPFPRINTF(("max packet %d\n", fragoff + ip_len)); 1259 goto bad; 1260 } 1261 max = fragoff + ip_len; 1262 1263 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) { 1264 1265 /* Fully buffer all of the fragments */ 1266 PF_FRAG_LOCK(); 1267 1268 pf_ip2key(h, dir, &key); 1269 frag = pf_find_fragment(&key, &V_pf_frag_tree); 1270 1271 /* Check if we saw the last fragment already */ 1272 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 1273 max > frag->fr_max) 1274 goto bad; 1275 1276 /* Might return a completely reassembled mbuf, or NULL */ 1277 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max)); 1278 verdict = pf_reassemble(m0, h, dir, reason); 1279 PF_FRAG_UNLOCK(); 1280 1281 if (verdict != PF_PASS) 1282 return (PF_DROP); 1283 1284 m = *m0; 1285 if (m == NULL) 1286 return (PF_DROP); 1287 1288 h = mtod(m, struct ip *); 1289 } else { 1290 /* non-buffering fragment cache (drops or masks overlaps) */ 1291 int nomem = 0; 1292 1293 if (dir == PF_OUT && pd->pf_mtag && 1294 pd->pf_mtag->flags & PF_TAG_FRAGCACHE) { 1295 /* 1296 * Already passed the fragment cache in the 1297 * input direction. If we continued, it would 1298 * appear to be a dup and would be dropped. 1299 */ 1300 goto fragment_pass; 1301 } 1302 1303 PF_FRAG_LOCK(); 1304 pf_ip2key(h, dir, &key); 1305 frag = pf_find_fragment(&key, &V_pf_cache_tree); 1306 1307 /* Check if we saw the last fragment already */ 1308 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 1309 max > frag->fr_max) { 1310 if (r->rule_flag & PFRULE_FRAGDROP) 1311 frag->fr_flags |= PFFRAG_DROP; 1312 goto bad; 1313 } 1314 1315 *m0 = m = pf_fragcache(m0, h, &frag, mff, 1316 (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem); 1317 PF_FRAG_UNLOCK(); 1318 if (m == NULL) { 1319 if (nomem) 1320 goto no_mem; 1321 goto drop; 1322 } 1323 1324 if (dir == PF_IN) { 1325 /* Use mtag from copied and trimmed mbuf chain. */ 1326 pd->pf_mtag = pf_get_mtag(m); 1327 if (pd->pf_mtag == NULL) { 1328 m_freem(m); 1329 *m0 = NULL; 1330 goto no_mem; 1331 } 1332 pd->pf_mtag->flags |= PF_TAG_FRAGCACHE; 1333 } 1334 1335 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP)) 1336 goto drop; 1337 goto fragment_pass; 1338 } 1339 1340 no_fragment: 1341 /* At this point, only IP_DF is allowed in ip_off */ 1342 if (h->ip_off & ~htons(IP_DF)) { 1343 u_int16_t ip_off = h->ip_off; 1344 1345 h->ip_off &= htons(IP_DF); 1346 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1347 } 1348 1349 /* not missing a return here */ 1350 1351 fragment_pass: 1352 pf_scrub_ip(&m, r->rule_flag, r->min_ttl, r->set_tos); 1353 1354 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) 1355 pd->flags |= PFDESC_IP_REAS; 1356 return (PF_PASS); 1357 1358 no_mem: 1359 REASON_SET(reason, PFRES_MEMORY); 1360 if (r != NULL && r->log) 1361 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd, 1362 1); 1363 return (PF_DROP); 1364 1365 drop: 1366 REASON_SET(reason, PFRES_NORM); 1367 if (r != NULL && r->log) 1368 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd, 1369 1); 1370 return (PF_DROP); 1371 1372 bad: 1373 DPFPRINTF(("dropping bad fragment\n")); 1374 1375 /* Free associated fragments */ 1376 if (frag != NULL) { 1377 pf_free_fragment(frag); 1378 PF_FRAG_UNLOCK(); 1379 } 1380 1381 REASON_SET(reason, PFRES_FRAG); 1382 if (r != NULL && r->log) 1383 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd, 1384 1); 1385 1386 return (PF_DROP); 1387 } 1388 #endif 1389 1390 #ifdef INET6 1391 int 1392 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif, 1393 u_short *reason, struct pf_pdesc *pd) 1394 { 1395 struct mbuf *m = *m0; 1396 struct pf_rule *r; 1397 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1398 int extoff; 1399 int off; 1400 struct ip6_ext ext; 1401 struct ip6_opt opt; 1402 struct ip6_opt_jumbo jumbo; 1403 struct ip6_frag frag; 1404 u_int32_t jumbolen = 0, plen; 1405 int optend; 1406 int ooff; 1407 u_int8_t proto; 1408 int terminal; 1409 1410 PF_RULES_RASSERT(); 1411 1412 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1413 while (r != NULL) { 1414 r->evaluations++; 1415 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1416 r = r->skip[PF_SKIP_IFP].ptr; 1417 else if (r->direction && r->direction != dir) 1418 r = r->skip[PF_SKIP_DIR].ptr; 1419 else if (r->af && r->af != AF_INET6) 1420 r = r->skip[PF_SKIP_AF].ptr; 1421 #if 0 /* header chain! */ 1422 else if (r->proto && r->proto != h->ip6_nxt) 1423 r = r->skip[PF_SKIP_PROTO].ptr; 1424 #endif 1425 else if (PF_MISMATCHAW(&r->src.addr, 1426 (struct pf_addr *)&h->ip6_src, AF_INET6, 1427 r->src.neg, kif, M_GETFIB(m))) 1428 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1429 else if (PF_MISMATCHAW(&r->dst.addr, 1430 (struct pf_addr *)&h->ip6_dst, AF_INET6, 1431 r->dst.neg, NULL, M_GETFIB(m))) 1432 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1433 else 1434 break; 1435 } 1436 1437 if (r == NULL || r->action == PF_NOSCRUB) 1438 return (PF_PASS); 1439 else { 1440 r->packets[dir == PF_OUT]++; 1441 r->bytes[dir == PF_OUT] += pd->tot_len; 1442 } 1443 1444 /* Check for illegal packets */ 1445 if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len) 1446 goto drop; 1447 1448 extoff = 0; 1449 off = sizeof(struct ip6_hdr); 1450 proto = h->ip6_nxt; 1451 terminal = 0; 1452 do { 1453 switch (proto) { 1454 case IPPROTO_FRAGMENT: 1455 goto fragment; 1456 break; 1457 case IPPROTO_AH: 1458 case IPPROTO_ROUTING: 1459 case IPPROTO_DSTOPTS: 1460 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1461 NULL, AF_INET6)) 1462 goto shortpkt; 1463 extoff = off; 1464 if (proto == IPPROTO_AH) 1465 off += (ext.ip6e_len + 2) * 4; 1466 else 1467 off += (ext.ip6e_len + 1) * 8; 1468 proto = ext.ip6e_nxt; 1469 break; 1470 case IPPROTO_HOPOPTS: 1471 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1472 NULL, AF_INET6)) 1473 goto shortpkt; 1474 extoff = off; 1475 optend = off + (ext.ip6e_len + 1) * 8; 1476 ooff = off + sizeof(ext); 1477 do { 1478 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type, 1479 sizeof(opt.ip6o_type), NULL, NULL, 1480 AF_INET6)) 1481 goto shortpkt; 1482 if (opt.ip6o_type == IP6OPT_PAD1) { 1483 ooff++; 1484 continue; 1485 } 1486 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt), 1487 NULL, NULL, AF_INET6)) 1488 goto shortpkt; 1489 if (ooff + sizeof(opt) + opt.ip6o_len > optend) 1490 goto drop; 1491 switch (opt.ip6o_type) { 1492 case IP6OPT_JUMBO: 1493 if (h->ip6_plen != 0) 1494 goto drop; 1495 if (!pf_pull_hdr(m, ooff, &jumbo, 1496 sizeof(jumbo), NULL, NULL, 1497 AF_INET6)) 1498 goto shortpkt; 1499 memcpy(&jumbolen, jumbo.ip6oj_jumbo_len, 1500 sizeof(jumbolen)); 1501 jumbolen = ntohl(jumbolen); 1502 if (jumbolen <= IPV6_MAXPACKET) 1503 goto drop; 1504 if (sizeof(struct ip6_hdr) + jumbolen != 1505 m->m_pkthdr.len) 1506 goto drop; 1507 break; 1508 default: 1509 break; 1510 } 1511 ooff += sizeof(opt) + opt.ip6o_len; 1512 } while (ooff < optend); 1513 1514 off = optend; 1515 proto = ext.ip6e_nxt; 1516 break; 1517 default: 1518 terminal = 1; 1519 break; 1520 } 1521 } while (!terminal); 1522 1523 /* jumbo payload option must be present, or plen > 0 */ 1524 if (ntohs(h->ip6_plen) == 0) 1525 plen = jumbolen; 1526 else 1527 plen = ntohs(h->ip6_plen); 1528 if (plen == 0) 1529 goto drop; 1530 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1531 goto shortpkt; 1532 1533 pf_scrub_ip6(&m, r->min_ttl); 1534 1535 return (PF_PASS); 1536 1537 fragment: 1538 /* Jumbo payload packets cannot be fragmented. */ 1539 plen = ntohs(h->ip6_plen); 1540 if (plen == 0 || jumbolen) 1541 goto drop; 1542 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1543 goto shortpkt; 1544 1545 if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6)) 1546 goto shortpkt; 1547 1548 /* Offset now points to data portion. */ 1549 off += sizeof(frag); 1550 1551 /* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */ 1552 if (pf_reassemble6(m0, h, &frag, off, extoff, reason) != PF_PASS) 1553 return (PF_DROP); 1554 m = *m0; 1555 if (m == NULL) 1556 return (PF_DROP); 1557 1558 pd->flags |= PFDESC_IP_REAS; 1559 return (PF_PASS); 1560 1561 shortpkt: 1562 REASON_SET(reason, PFRES_SHORT); 1563 if (r != NULL && r->log) 1564 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd, 1565 1); 1566 return (PF_DROP); 1567 1568 drop: 1569 REASON_SET(reason, PFRES_NORM); 1570 if (r != NULL && r->log) 1571 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd, 1572 1); 1573 return (PF_DROP); 1574 } 1575 #endif /* INET6 */ 1576 1577 int 1578 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff, 1579 int off, void *h, struct pf_pdesc *pd) 1580 { 1581 struct pf_rule *r, *rm = NULL; 1582 struct tcphdr *th = pd->hdr.tcp; 1583 int rewrite = 0; 1584 u_short reason; 1585 u_int8_t flags; 1586 sa_family_t af = pd->af; 1587 1588 PF_RULES_RASSERT(); 1589 1590 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1591 while (r != NULL) { 1592 r->evaluations++; 1593 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1594 r = r->skip[PF_SKIP_IFP].ptr; 1595 else if (r->direction && r->direction != dir) 1596 r = r->skip[PF_SKIP_DIR].ptr; 1597 else if (r->af && r->af != af) 1598 r = r->skip[PF_SKIP_AF].ptr; 1599 else if (r->proto && r->proto != pd->proto) 1600 r = r->skip[PF_SKIP_PROTO].ptr; 1601 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, 1602 r->src.neg, kif, M_GETFIB(m))) 1603 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1604 else if (r->src.port_op && !pf_match_port(r->src.port_op, 1605 r->src.port[0], r->src.port[1], th->th_sport)) 1606 r = r->skip[PF_SKIP_SRC_PORT].ptr; 1607 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, 1608 r->dst.neg, NULL, M_GETFIB(m))) 1609 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1610 else if (r->dst.port_op && !pf_match_port(r->dst.port_op, 1611 r->dst.port[0], r->dst.port[1], th->th_dport)) 1612 r = r->skip[PF_SKIP_DST_PORT].ptr; 1613 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match( 1614 pf_osfp_fingerprint(pd, m, off, th), 1615 r->os_fingerprint)) 1616 r = TAILQ_NEXT(r, entries); 1617 else { 1618 rm = r; 1619 break; 1620 } 1621 } 1622 1623 if (rm == NULL || rm->action == PF_NOSCRUB) 1624 return (PF_PASS); 1625 else { 1626 r->packets[dir == PF_OUT]++; 1627 r->bytes[dir == PF_OUT] += pd->tot_len; 1628 } 1629 1630 if (rm->rule_flag & PFRULE_REASSEMBLE_TCP) 1631 pd->flags |= PFDESC_TCP_NORM; 1632 1633 flags = th->th_flags; 1634 if (flags & TH_SYN) { 1635 /* Illegal packet */ 1636 if (flags & TH_RST) 1637 goto tcp_drop; 1638 1639 if (flags & TH_FIN) 1640 goto tcp_drop; 1641 } else { 1642 /* Illegal packet */ 1643 if (!(flags & (TH_ACK|TH_RST))) 1644 goto tcp_drop; 1645 } 1646 1647 if (!(flags & TH_ACK)) { 1648 /* These flags are only valid if ACK is set */ 1649 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG)) 1650 goto tcp_drop; 1651 } 1652 1653 /* Check for illegal header length */ 1654 if (th->th_off < (sizeof(struct tcphdr) >> 2)) 1655 goto tcp_drop; 1656 1657 /* If flags changed, or reserved data set, then adjust */ 1658 if (flags != th->th_flags || th->th_x2 != 0) { 1659 u_int16_t ov, nv; 1660 1661 ov = *(u_int16_t *)(&th->th_ack + 1); 1662 th->th_flags = flags; 1663 th->th_x2 = 0; 1664 nv = *(u_int16_t *)(&th->th_ack + 1); 1665 1666 th->th_sum = pf_cksum_fixup(th->th_sum, ov, nv, 0); 1667 rewrite = 1; 1668 } 1669 1670 /* Remove urgent pointer, if TH_URG is not set */ 1671 if (!(flags & TH_URG) && th->th_urp) { 1672 th->th_sum = pf_cksum_fixup(th->th_sum, th->th_urp, 0, 0); 1673 th->th_urp = 0; 1674 rewrite = 1; 1675 } 1676 1677 /* Process options */ 1678 if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af)) 1679 rewrite = 1; 1680 1681 /* copy back packet headers if we sanitized */ 1682 if (rewrite) 1683 m_copyback(m, off, sizeof(*th), (caddr_t)th); 1684 1685 return (PF_PASS); 1686 1687 tcp_drop: 1688 REASON_SET(&reason, PFRES_NORM); 1689 if (rm != NULL && r->log) 1690 PFLOG_PACKET(kif, m, AF_INET, dir, reason, r, NULL, NULL, pd, 1691 1); 1692 return (PF_DROP); 1693 } 1694 1695 int 1696 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd, 1697 struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst) 1698 { 1699 u_int32_t tsval, tsecr; 1700 u_int8_t hdr[60]; 1701 u_int8_t *opt; 1702 1703 KASSERT((src->scrub == NULL), 1704 ("pf_normalize_tcp_init: src->scrub != NULL")); 1705 1706 src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT); 1707 if (src->scrub == NULL) 1708 return (1); 1709 1710 switch (pd->af) { 1711 #ifdef INET 1712 case AF_INET: { 1713 struct ip *h = mtod(m, struct ip *); 1714 src->scrub->pfss_ttl = h->ip_ttl; 1715 break; 1716 } 1717 #endif /* INET */ 1718 #ifdef INET6 1719 case AF_INET6: { 1720 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1721 src->scrub->pfss_ttl = h->ip6_hlim; 1722 break; 1723 } 1724 #endif /* INET6 */ 1725 } 1726 1727 1728 /* 1729 * All normalizations below are only begun if we see the start of 1730 * the connections. They must all set an enabled bit in pfss_flags 1731 */ 1732 if ((th->th_flags & TH_SYN) == 0) 1733 return (0); 1734 1735 1736 if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub && 1737 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1738 /* Diddle with TCP options */ 1739 int hlen; 1740 opt = hdr + sizeof(struct tcphdr); 1741 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1742 while (hlen >= TCPOLEN_TIMESTAMP) { 1743 switch (*opt) { 1744 case TCPOPT_EOL: /* FALLTHROUGH */ 1745 case TCPOPT_NOP: 1746 opt++; 1747 hlen--; 1748 break; 1749 case TCPOPT_TIMESTAMP: 1750 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1751 src->scrub->pfss_flags |= 1752 PFSS_TIMESTAMP; 1753 src->scrub->pfss_ts_mod = 1754 htonl(arc4random()); 1755 1756 /* note PFSS_PAWS not set yet */ 1757 memcpy(&tsval, &opt[2], 1758 sizeof(u_int32_t)); 1759 memcpy(&tsecr, &opt[6], 1760 sizeof(u_int32_t)); 1761 src->scrub->pfss_tsval0 = ntohl(tsval); 1762 src->scrub->pfss_tsval = ntohl(tsval); 1763 src->scrub->pfss_tsecr = ntohl(tsecr); 1764 getmicrouptime(&src->scrub->pfss_last); 1765 } 1766 /* FALLTHROUGH */ 1767 default: 1768 hlen -= MAX(opt[1], 2); 1769 opt += MAX(opt[1], 2); 1770 break; 1771 } 1772 } 1773 } 1774 1775 return (0); 1776 } 1777 1778 void 1779 pf_normalize_tcp_cleanup(struct pf_state *state) 1780 { 1781 if (state->src.scrub) 1782 uma_zfree(V_pf_state_scrub_z, state->src.scrub); 1783 if (state->dst.scrub) 1784 uma_zfree(V_pf_state_scrub_z, state->dst.scrub); 1785 1786 /* Someday... flush the TCP segment reassembly descriptors. */ 1787 } 1788 1789 int 1790 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd, 1791 u_short *reason, struct tcphdr *th, struct pf_state *state, 1792 struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback) 1793 { 1794 struct timeval uptime; 1795 u_int32_t tsval, tsecr; 1796 u_int tsval_from_last; 1797 u_int8_t hdr[60]; 1798 u_int8_t *opt; 1799 int copyback = 0; 1800 int got_ts = 0; 1801 1802 KASSERT((src->scrub || dst->scrub), 1803 ("%s: src->scrub && dst->scrub!", __func__)); 1804 1805 /* 1806 * Enforce the minimum TTL seen for this connection. Negate a common 1807 * technique to evade an intrusion detection system and confuse 1808 * firewall state code. 1809 */ 1810 switch (pd->af) { 1811 #ifdef INET 1812 case AF_INET: { 1813 if (src->scrub) { 1814 struct ip *h = mtod(m, struct ip *); 1815 if (h->ip_ttl > src->scrub->pfss_ttl) 1816 src->scrub->pfss_ttl = h->ip_ttl; 1817 h->ip_ttl = src->scrub->pfss_ttl; 1818 } 1819 break; 1820 } 1821 #endif /* INET */ 1822 #ifdef INET6 1823 case AF_INET6: { 1824 if (src->scrub) { 1825 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1826 if (h->ip6_hlim > src->scrub->pfss_ttl) 1827 src->scrub->pfss_ttl = h->ip6_hlim; 1828 h->ip6_hlim = src->scrub->pfss_ttl; 1829 } 1830 break; 1831 } 1832 #endif /* INET6 */ 1833 } 1834 1835 if (th->th_off > (sizeof(struct tcphdr) >> 2) && 1836 ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) || 1837 (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) && 1838 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1839 /* Diddle with TCP options */ 1840 int hlen; 1841 opt = hdr + sizeof(struct tcphdr); 1842 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1843 while (hlen >= TCPOLEN_TIMESTAMP) { 1844 switch (*opt) { 1845 case TCPOPT_EOL: /* FALLTHROUGH */ 1846 case TCPOPT_NOP: 1847 opt++; 1848 hlen--; 1849 break; 1850 case TCPOPT_TIMESTAMP: 1851 /* Modulate the timestamps. Can be used for 1852 * NAT detection, OS uptime determination or 1853 * reboot detection. 1854 */ 1855 1856 if (got_ts) { 1857 /* Huh? Multiple timestamps!? */ 1858 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1859 DPFPRINTF(("multiple TS??")); 1860 pf_print_state(state); 1861 printf("\n"); 1862 } 1863 REASON_SET(reason, PFRES_TS); 1864 return (PF_DROP); 1865 } 1866 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1867 memcpy(&tsval, &opt[2], 1868 sizeof(u_int32_t)); 1869 if (tsval && src->scrub && 1870 (src->scrub->pfss_flags & 1871 PFSS_TIMESTAMP)) { 1872 tsval = ntohl(tsval); 1873 pf_change_a(&opt[2], 1874 &th->th_sum, 1875 htonl(tsval + 1876 src->scrub->pfss_ts_mod), 1877 0); 1878 copyback = 1; 1879 } 1880 1881 /* Modulate TS reply iff valid (!0) */ 1882 memcpy(&tsecr, &opt[6], 1883 sizeof(u_int32_t)); 1884 if (tsecr && dst->scrub && 1885 (dst->scrub->pfss_flags & 1886 PFSS_TIMESTAMP)) { 1887 tsecr = ntohl(tsecr) 1888 - dst->scrub->pfss_ts_mod; 1889 pf_change_a(&opt[6], 1890 &th->th_sum, htonl(tsecr), 1891 0); 1892 copyback = 1; 1893 } 1894 got_ts = 1; 1895 } 1896 /* FALLTHROUGH */ 1897 default: 1898 hlen -= MAX(opt[1], 2); 1899 opt += MAX(opt[1], 2); 1900 break; 1901 } 1902 } 1903 if (copyback) { 1904 /* Copyback the options, caller copys back header */ 1905 *writeback = 1; 1906 m_copyback(m, off + sizeof(struct tcphdr), 1907 (th->th_off << 2) - sizeof(struct tcphdr), hdr + 1908 sizeof(struct tcphdr)); 1909 } 1910 } 1911 1912 1913 /* 1914 * Must invalidate PAWS checks on connections idle for too long. 1915 * The fastest allowed timestamp clock is 1ms. That turns out to 1916 * be about 24 days before it wraps. XXX Right now our lowerbound 1917 * TS echo check only works for the first 12 days of a connection 1918 * when the TS has exhausted half its 32bit space 1919 */ 1920 #define TS_MAX_IDLE (24*24*60*60) 1921 #define TS_MAX_CONN (12*24*60*60) /* XXX remove when better tsecr check */ 1922 1923 getmicrouptime(&uptime); 1924 if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) && 1925 (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE || 1926 time_uptime - state->creation > TS_MAX_CONN)) { 1927 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1928 DPFPRINTF(("src idled out of PAWS\n")); 1929 pf_print_state(state); 1930 printf("\n"); 1931 } 1932 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS) 1933 | PFSS_PAWS_IDLED; 1934 } 1935 if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) && 1936 uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) { 1937 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1938 DPFPRINTF(("dst idled out of PAWS\n")); 1939 pf_print_state(state); 1940 printf("\n"); 1941 } 1942 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS) 1943 | PFSS_PAWS_IDLED; 1944 } 1945 1946 if (got_ts && src->scrub && dst->scrub && 1947 (src->scrub->pfss_flags & PFSS_PAWS) && 1948 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1949 /* Validate that the timestamps are "in-window". 1950 * RFC1323 describes TCP Timestamp options that allow 1951 * measurement of RTT (round trip time) and PAWS 1952 * (protection against wrapped sequence numbers). PAWS 1953 * gives us a set of rules for rejecting packets on 1954 * long fat pipes (packets that were somehow delayed 1955 * in transit longer than the time it took to send the 1956 * full TCP sequence space of 4Gb). We can use these 1957 * rules and infer a few others that will let us treat 1958 * the 32bit timestamp and the 32bit echoed timestamp 1959 * as sequence numbers to prevent a blind attacker from 1960 * inserting packets into a connection. 1961 * 1962 * RFC1323 tells us: 1963 * - The timestamp on this packet must be greater than 1964 * or equal to the last value echoed by the other 1965 * endpoint. The RFC says those will be discarded 1966 * since it is a dup that has already been acked. 1967 * This gives us a lowerbound on the timestamp. 1968 * timestamp >= other last echoed timestamp 1969 * - The timestamp will be less than or equal to 1970 * the last timestamp plus the time between the 1971 * last packet and now. The RFC defines the max 1972 * clock rate as 1ms. We will allow clocks to be 1973 * up to 10% fast and will allow a total difference 1974 * or 30 seconds due to a route change. And this 1975 * gives us an upperbound on the timestamp. 1976 * timestamp <= last timestamp + max ticks 1977 * We have to be careful here. Windows will send an 1978 * initial timestamp of zero and then initialize it 1979 * to a random value after the 3whs; presumably to 1980 * avoid a DoS by having to call an expensive RNG 1981 * during a SYN flood. Proof MS has at least one 1982 * good security geek. 1983 * 1984 * - The TCP timestamp option must also echo the other 1985 * endpoints timestamp. The timestamp echoed is the 1986 * one carried on the earliest unacknowledged segment 1987 * on the left edge of the sequence window. The RFC 1988 * states that the host will reject any echoed 1989 * timestamps that were larger than any ever sent. 1990 * This gives us an upperbound on the TS echo. 1991 * tescr <= largest_tsval 1992 * - The lowerbound on the TS echo is a little more 1993 * tricky to determine. The other endpoint's echoed 1994 * values will not decrease. But there may be 1995 * network conditions that re-order packets and 1996 * cause our view of them to decrease. For now the 1997 * only lowerbound we can safely determine is that 1998 * the TS echo will never be less than the original 1999 * TS. XXX There is probably a better lowerbound. 2000 * Remove TS_MAX_CONN with better lowerbound check. 2001 * tescr >= other original TS 2002 * 2003 * It is also important to note that the fastest 2004 * timestamp clock of 1ms will wrap its 32bit space in 2005 * 24 days. So we just disable TS checking after 24 2006 * days of idle time. We actually must use a 12d 2007 * connection limit until we can come up with a better 2008 * lowerbound to the TS echo check. 2009 */ 2010 struct timeval delta_ts; 2011 int ts_fudge; 2012 2013 2014 /* 2015 * PFTM_TS_DIFF is how many seconds of leeway to allow 2016 * a host's timestamp. This can happen if the previous 2017 * packet got delayed in transit for much longer than 2018 * this packet. 2019 */ 2020 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0) 2021 ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF]; 2022 2023 /* Calculate max ticks since the last timestamp */ 2024 #define TS_MAXFREQ 1100 /* RFC max TS freq of 1Khz + 10% skew */ 2025 #define TS_MICROSECS 1000000 /* microseconds per second */ 2026 delta_ts = uptime; 2027 timevalsub(&delta_ts, &src->scrub->pfss_last); 2028 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ; 2029 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ); 2030 2031 if ((src->state >= TCPS_ESTABLISHED && 2032 dst->state >= TCPS_ESTABLISHED) && 2033 (SEQ_LT(tsval, dst->scrub->pfss_tsecr) || 2034 SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) || 2035 (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) || 2036 SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) { 2037 /* Bad RFC1323 implementation or an insertion attack. 2038 * 2039 * - Solaris 2.6 and 2.7 are known to send another ACK 2040 * after the FIN,FIN|ACK,ACK closing that carries 2041 * an old timestamp. 2042 */ 2043 2044 DPFPRINTF(("Timestamp failed %c%c%c%c\n", 2045 SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ', 2046 SEQ_GT(tsval, src->scrub->pfss_tsval + 2047 tsval_from_last) ? '1' : ' ', 2048 SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ', 2049 SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' ')); 2050 DPFPRINTF((" tsval: %u tsecr: %u +ticks: %u " 2051 "idle: %jus %lums\n", 2052 tsval, tsecr, tsval_from_last, 2053 (uintmax_t)delta_ts.tv_sec, 2054 delta_ts.tv_usec / 1000)); 2055 DPFPRINTF((" src->tsval: %u tsecr: %u\n", 2056 src->scrub->pfss_tsval, src->scrub->pfss_tsecr)); 2057 DPFPRINTF((" dst->tsval: %u tsecr: %u tsval0: %u" 2058 "\n", dst->scrub->pfss_tsval, 2059 dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0)); 2060 if (V_pf_status.debug >= PF_DEBUG_MISC) { 2061 pf_print_state(state); 2062 pf_print_flags(th->th_flags); 2063 printf("\n"); 2064 } 2065 REASON_SET(reason, PFRES_TS); 2066 return (PF_DROP); 2067 } 2068 2069 /* XXX I'd really like to require tsecr but it's optional */ 2070 2071 } else if (!got_ts && (th->th_flags & TH_RST) == 0 && 2072 ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED) 2073 || pd->p_len > 0 || (th->th_flags & TH_SYN)) && 2074 src->scrub && dst->scrub && 2075 (src->scrub->pfss_flags & PFSS_PAWS) && 2076 (dst->scrub->pfss_flags & PFSS_PAWS)) { 2077 /* Didn't send a timestamp. Timestamps aren't really useful 2078 * when: 2079 * - connection opening or closing (often not even sent). 2080 * but we must not let an attacker to put a FIN on a 2081 * data packet to sneak it through our ESTABLISHED check. 2082 * - on a TCP reset. RFC suggests not even looking at TS. 2083 * - on an empty ACK. The TS will not be echoed so it will 2084 * probably not help keep the RTT calculation in sync and 2085 * there isn't as much danger when the sequence numbers 2086 * got wrapped. So some stacks don't include TS on empty 2087 * ACKs :-( 2088 * 2089 * To minimize the disruption to mostly RFC1323 conformant 2090 * stacks, we will only require timestamps on data packets. 2091 * 2092 * And what do ya know, we cannot require timestamps on data 2093 * packets. There appear to be devices that do legitimate 2094 * TCP connection hijacking. There are HTTP devices that allow 2095 * a 3whs (with timestamps) and then buffer the HTTP request. 2096 * If the intermediate device has the HTTP response cache, it 2097 * will spoof the response but not bother timestamping its 2098 * packets. So we can look for the presence of a timestamp in 2099 * the first data packet and if there, require it in all future 2100 * packets. 2101 */ 2102 2103 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) { 2104 /* 2105 * Hey! Someone tried to sneak a packet in. Or the 2106 * stack changed its RFC1323 behavior?!?! 2107 */ 2108 if (V_pf_status.debug >= PF_DEBUG_MISC) { 2109 DPFPRINTF(("Did not receive expected RFC1323 " 2110 "timestamp\n")); 2111 pf_print_state(state); 2112 pf_print_flags(th->th_flags); 2113 printf("\n"); 2114 } 2115 REASON_SET(reason, PFRES_TS); 2116 return (PF_DROP); 2117 } 2118 } 2119 2120 2121 /* 2122 * We will note if a host sends his data packets with or without 2123 * timestamps. And require all data packets to contain a timestamp 2124 * if the first does. PAWS implicitly requires that all data packets be 2125 * timestamped. But I think there are middle-man devices that hijack 2126 * TCP streams immediately after the 3whs and don't timestamp their 2127 * packets (seen in a WWW accelerator or cache). 2128 */ 2129 if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags & 2130 (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) { 2131 if (got_ts) 2132 src->scrub->pfss_flags |= PFSS_DATA_TS; 2133 else { 2134 src->scrub->pfss_flags |= PFSS_DATA_NOTS; 2135 if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub && 2136 (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) { 2137 /* Don't warn if other host rejected RFC1323 */ 2138 DPFPRINTF(("Broken RFC1323 stack did not " 2139 "timestamp data packet. Disabled PAWS " 2140 "security.\n")); 2141 pf_print_state(state); 2142 pf_print_flags(th->th_flags); 2143 printf("\n"); 2144 } 2145 } 2146 } 2147 2148 2149 /* 2150 * Update PAWS values 2151 */ 2152 if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags & 2153 (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) { 2154 getmicrouptime(&src->scrub->pfss_last); 2155 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) || 2156 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 2157 src->scrub->pfss_tsval = tsval; 2158 2159 if (tsecr) { 2160 if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) || 2161 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 2162 src->scrub->pfss_tsecr = tsecr; 2163 2164 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 && 2165 (SEQ_LT(tsval, src->scrub->pfss_tsval0) || 2166 src->scrub->pfss_tsval0 == 0)) { 2167 /* tsval0 MUST be the lowest timestamp */ 2168 src->scrub->pfss_tsval0 = tsval; 2169 } 2170 2171 /* Only fully initialized after a TS gets echoed */ 2172 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0) 2173 src->scrub->pfss_flags |= PFSS_PAWS; 2174 } 2175 } 2176 2177 /* I have a dream.... TCP segment reassembly.... */ 2178 return (0); 2179 } 2180 2181 static int 2182 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th, 2183 int off, sa_family_t af) 2184 { 2185 u_int16_t *mss; 2186 int thoff; 2187 int opt, cnt, optlen = 0; 2188 int rewrite = 0; 2189 u_char opts[TCP_MAXOLEN]; 2190 u_char *optp = opts; 2191 2192 thoff = th->th_off << 2; 2193 cnt = thoff - sizeof(struct tcphdr); 2194 2195 if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt, 2196 NULL, NULL, af)) 2197 return (rewrite); 2198 2199 for (; cnt > 0; cnt -= optlen, optp += optlen) { 2200 opt = optp[0]; 2201 if (opt == TCPOPT_EOL) 2202 break; 2203 if (opt == TCPOPT_NOP) 2204 optlen = 1; 2205 else { 2206 if (cnt < 2) 2207 break; 2208 optlen = optp[1]; 2209 if (optlen < 2 || optlen > cnt) 2210 break; 2211 } 2212 switch (opt) { 2213 case TCPOPT_MAXSEG: 2214 mss = (u_int16_t *)(optp + 2); 2215 if ((ntohs(*mss)) > r->max_mss) { 2216 th->th_sum = pf_cksum_fixup(th->th_sum, 2217 *mss, htons(r->max_mss), 0); 2218 *mss = htons(r->max_mss); 2219 rewrite = 1; 2220 } 2221 break; 2222 default: 2223 break; 2224 } 2225 } 2226 2227 if (rewrite) 2228 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts); 2229 2230 return (rewrite); 2231 } 2232 2233 #ifdef INET 2234 static void 2235 pf_scrub_ip(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos) 2236 { 2237 struct mbuf *m = *m0; 2238 struct ip *h = mtod(m, struct ip *); 2239 2240 /* Clear IP_DF if no-df was requested */ 2241 if (flags & PFRULE_NODF && h->ip_off & htons(IP_DF)) { 2242 u_int16_t ip_off = h->ip_off; 2243 2244 h->ip_off &= htons(~IP_DF); 2245 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 2246 } 2247 2248 /* Enforce a minimum ttl, may cause endless packet loops */ 2249 if (min_ttl && h->ip_ttl < min_ttl) { 2250 u_int16_t ip_ttl = h->ip_ttl; 2251 2252 h->ip_ttl = min_ttl; 2253 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0); 2254 } 2255 2256 /* Enforce tos */ 2257 if (flags & PFRULE_SET_TOS) { 2258 u_int16_t ov, nv; 2259 2260 ov = *(u_int16_t *)h; 2261 h->ip_tos = tos; 2262 nv = *(u_int16_t *)h; 2263 2264 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0); 2265 } 2266 2267 /* random-id, but not for fragments */ 2268 if (flags & PFRULE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) { 2269 uint16_t ip_id = h->ip_id; 2270 2271 ip_fillid(h); 2272 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0); 2273 } 2274 } 2275 #endif /* INET */ 2276 2277 #ifdef INET6 2278 static void 2279 pf_scrub_ip6(struct mbuf **m0, u_int8_t min_ttl) 2280 { 2281 struct mbuf *m = *m0; 2282 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 2283 2284 /* Enforce a minimum ttl, may cause endless packet loops */ 2285 if (min_ttl && h->ip6_hlim < min_ttl) 2286 h->ip6_hlim = min_ttl; 2287 } 2288 #endif 2289