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_timeout = time_second; 435 frag->fr_maxlen = frent->fe_len; 436 TAILQ_INIT(&frag->fr_queue); 437 438 RB_INSERT(pf_frag_tree, &V_pf_frag_tree, frag); 439 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next); 440 441 /* We do not have a previous fragment. */ 442 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next); 443 444 return (frag); 445 } 446 447 KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue")); 448 449 /* Remember maximum fragment len for refragmentation. */ 450 if (frent->fe_len > frag->fr_maxlen) 451 frag->fr_maxlen = frent->fe_len; 452 453 /* Maximum data we have seen already. */ 454 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 455 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 456 457 /* Non terminal fragments must have more fragments flag. */ 458 if (frent->fe_off + frent->fe_len < total && !frent->fe_mff) 459 goto bad_fragment; 460 461 /* Check if we saw the last fragment already. */ 462 if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) { 463 if (frent->fe_off + frent->fe_len > total || 464 (frent->fe_off + frent->fe_len == total && frent->fe_mff)) 465 goto bad_fragment; 466 } else { 467 if (frent->fe_off + frent->fe_len == total && !frent->fe_mff) 468 goto bad_fragment; 469 } 470 471 /* Find a fragment after the current one. */ 472 prev = NULL; 473 TAILQ_FOREACH(after, &frag->fr_queue, fr_next) { 474 if (after->fe_off > frent->fe_off) 475 break; 476 prev = after; 477 } 478 479 KASSERT(prev != NULL || after != NULL, 480 ("prev != NULL || after != NULL")); 481 482 if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) { 483 uint16_t precut; 484 485 precut = prev->fe_off + prev->fe_len - frent->fe_off; 486 if (precut >= frent->fe_len) 487 goto bad_fragment; 488 DPFPRINTF(("overlap -%d", precut)); 489 m_adj(frent->fe_m, precut); 490 frent->fe_off += precut; 491 frent->fe_len -= precut; 492 } 493 494 for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off; 495 after = next) { 496 uint16_t aftercut; 497 498 aftercut = frent->fe_off + frent->fe_len - after->fe_off; 499 DPFPRINTF(("adjust overlap %d", aftercut)); 500 if (aftercut < after->fe_len) { 501 m_adj(after->fe_m, aftercut); 502 after->fe_off += aftercut; 503 after->fe_len -= aftercut; 504 break; 505 } 506 507 /* This fragment is completely overlapped, lose it. */ 508 next = TAILQ_NEXT(after, fr_next); 509 m_freem(after->fe_m); 510 TAILQ_REMOVE(&frag->fr_queue, after, fr_next); 511 uma_zfree(V_pf_frent_z, after); 512 } 513 514 if (prev == NULL) 515 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next); 516 else 517 TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next); 518 519 return (frag); 520 521 bad_fragment: 522 REASON_SET(reason, PFRES_FRAG); 523 drop_fragment: 524 uma_zfree(V_pf_frent_z, frent); 525 return (NULL); 526 } 527 528 static int 529 pf_isfull_fragment(struct pf_fragment *frag) 530 { 531 struct pf_frent *frent, *next; 532 uint16_t off, total; 533 534 /* Check if we are completely reassembled */ 535 if (TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) 536 return (0); 537 538 /* Maximum data we have seen already */ 539 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 540 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 541 542 /* Check if we have all the data */ 543 off = 0; 544 for (frent = TAILQ_FIRST(&frag->fr_queue); frent; frent = next) { 545 next = TAILQ_NEXT(frent, fr_next); 546 547 off += frent->fe_len; 548 if (off < total && (next == NULL || next->fe_off != off)) { 549 DPFPRINTF(("missing fragment at %d, next %d, total %d", 550 off, next == NULL ? -1 : next->fe_off, total)); 551 return (0); 552 } 553 } 554 DPFPRINTF(("%d < %d?", off, total)); 555 if (off < total) 556 return (0); 557 KASSERT(off == total, ("off == total")); 558 559 return (1); 560 } 561 562 static struct mbuf * 563 pf_join_fragment(struct pf_fragment *frag) 564 { 565 struct mbuf *m, *m2; 566 struct pf_frent *frent, *next; 567 568 frent = TAILQ_FIRST(&frag->fr_queue); 569 next = TAILQ_NEXT(frent, fr_next); 570 571 m = frent->fe_m; 572 m_adj(m, (frent->fe_hdrlen + frent->fe_len) - m->m_pkthdr.len); 573 uma_zfree(V_pf_frent_z, frent); 574 for (frent = next; frent != NULL; frent = next) { 575 next = TAILQ_NEXT(frent, fr_next); 576 577 m2 = frent->fe_m; 578 /* Strip off ip header. */ 579 m_adj(m2, frent->fe_hdrlen); 580 /* Strip off any trailing bytes. */ 581 m_adj(m2, frent->fe_len - m2->m_pkthdr.len); 582 583 uma_zfree(V_pf_frent_z, frent); 584 m_cat(m, m2); 585 } 586 587 /* Remove from fragment queue. */ 588 pf_remove_fragment(frag); 589 590 return (m); 591 } 592 593 #ifdef INET 594 static int 595 pf_reassemble(struct mbuf **m0, struct ip *ip, int dir, u_short *reason) 596 { 597 struct mbuf *m = *m0; 598 struct pf_frent *frent; 599 struct pf_fragment *frag; 600 struct pf_fragment_cmp key; 601 uint16_t total, hdrlen; 602 603 /* Get an entry for the fragment queue */ 604 if ((frent = pf_create_fragment(reason)) == NULL) 605 return (PF_DROP); 606 607 frent->fe_m = m; 608 frent->fe_hdrlen = ip->ip_hl << 2; 609 frent->fe_extoff = 0; 610 frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2); 611 frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3; 612 frent->fe_mff = ntohs(ip->ip_off) & IP_MF; 613 614 pf_ip2key(ip, dir, &key); 615 616 if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) 617 return (PF_DROP); 618 619 /* The mbuf is part of the fragment entry, no direct free or access */ 620 m = *m0 = NULL; 621 622 if (!pf_isfull_fragment(frag)) 623 return (PF_PASS); /* drop because *m0 is NULL, no error */ 624 625 /* We have all the data */ 626 frent = TAILQ_FIRST(&frag->fr_queue); 627 KASSERT(frent != NULL, ("frent != NULL")); 628 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 629 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 630 hdrlen = frent->fe_hdrlen; 631 632 m = *m0 = pf_join_fragment(frag); 633 frag = NULL; 634 635 if (m->m_flags & M_PKTHDR) { 636 int plen = 0; 637 for (m = *m0; m; m = m->m_next) 638 plen += m->m_len; 639 m = *m0; 640 m->m_pkthdr.len = plen; 641 } 642 643 ip = mtod(m, struct ip *); 644 ip->ip_len = htons(hdrlen + total); 645 ip->ip_off &= ~(IP_MF|IP_OFFMASK); 646 647 if (hdrlen + total > IP_MAXPACKET) { 648 DPFPRINTF(("drop: too big: %d", total)); 649 ip->ip_len = 0; 650 REASON_SET(reason, PFRES_SHORT); 651 /* PF_DROP requires a valid mbuf *m0 in pf_test() */ 652 return (PF_DROP); 653 } 654 655 DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len))); 656 return (PF_PASS); 657 } 658 #endif /* INET */ 659 660 #ifdef INET6 661 static int 662 pf_reassemble6(struct mbuf **m0, struct ip6_hdr *ip6, struct ip6_frag *fraghdr, 663 uint16_t hdrlen, uint16_t extoff, u_short *reason) 664 { 665 struct mbuf *m = *m0; 666 struct pf_frent *frent; 667 struct pf_fragment *frag; 668 struct pf_fragment_cmp key; 669 struct m_tag *mtag; 670 struct pf_fragment_tag *ftag; 671 int off; 672 uint32_t frag_id; 673 uint16_t total, maxlen; 674 uint8_t proto; 675 676 PF_FRAG_LOCK(); 677 678 /* Get an entry for the fragment queue. */ 679 if ((frent = pf_create_fragment(reason)) == NULL) { 680 PF_FRAG_UNLOCK(); 681 return (PF_DROP); 682 } 683 684 frent->fe_m = m; 685 frent->fe_hdrlen = hdrlen; 686 frent->fe_extoff = extoff; 687 frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen; 688 frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK); 689 frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG; 690 691 key.frc_src.v6 = ip6->ip6_src; 692 key.frc_dst.v6 = ip6->ip6_dst; 693 key.frc_af = AF_INET6; 694 /* Only the first fragment's protocol is relevant. */ 695 key.frc_proto = 0; 696 key.frc_id = fraghdr->ip6f_ident; 697 698 if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) { 699 PF_FRAG_UNLOCK(); 700 return (PF_DROP); 701 } 702 703 /* The mbuf is part of the fragment entry, no direct free or access. */ 704 m = *m0 = NULL; 705 706 if (!pf_isfull_fragment(frag)) { 707 PF_FRAG_UNLOCK(); 708 return (PF_PASS); /* Drop because *m0 is NULL, no error. */ 709 } 710 711 /* We have all the data. */ 712 extoff = frent->fe_extoff; 713 maxlen = frag->fr_maxlen; 714 frag_id = frag->fr_id; 715 frent = TAILQ_FIRST(&frag->fr_queue); 716 KASSERT(frent != NULL, ("frent != NULL")); 717 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 718 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 719 hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag); 720 721 m = *m0 = pf_join_fragment(frag); 722 frag = NULL; 723 724 PF_FRAG_UNLOCK(); 725 726 /* Take protocol from first fragment header. */ 727 m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off); 728 KASSERT(m, ("%s: short mbuf chain", __func__)); 729 proto = *(mtod(m, caddr_t) + off); 730 m = *m0; 731 732 /* Delete frag6 header */ 733 if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0) 734 goto fail; 735 736 if (m->m_flags & M_PKTHDR) { 737 int plen = 0; 738 for (m = *m0; m; m = m->m_next) 739 plen += m->m_len; 740 m = *m0; 741 m->m_pkthdr.len = plen; 742 } 743 744 if ((mtag = m_tag_get(PF_REASSEMBLED, sizeof(struct pf_fragment_tag), 745 M_NOWAIT)) == NULL) 746 goto fail; 747 ftag = (struct pf_fragment_tag *)(mtag + 1); 748 ftag->ft_hdrlen = hdrlen; 749 ftag->ft_extoff = extoff; 750 ftag->ft_maxlen = maxlen; 751 ftag->ft_id = frag_id; 752 m_tag_prepend(m, mtag); 753 754 ip6 = mtod(m, struct ip6_hdr *); 755 ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total); 756 if (extoff) { 757 /* Write protocol into next field of last extension header. */ 758 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt), 759 &off); 760 KASSERT(m, ("%s: short mbuf chain", __func__)); 761 *(mtod(m, char *) + off) = proto; 762 m = *m0; 763 } else 764 ip6->ip6_nxt = proto; 765 766 if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) { 767 DPFPRINTF(("drop: too big: %d", total)); 768 ip6->ip6_plen = 0; 769 REASON_SET(reason, PFRES_SHORT); 770 /* PF_DROP requires a valid mbuf *m0 in pf_test6(). */ 771 return (PF_DROP); 772 } 773 774 DPFPRINTF(("complete: %p(%d)", m, ntohs(ip6->ip6_plen))); 775 return (PF_PASS); 776 777 fail: 778 REASON_SET(reason, PFRES_MEMORY); 779 /* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */ 780 return (PF_DROP); 781 } 782 #endif /* INET6 */ 783 784 #ifdef INET 785 static struct mbuf * 786 pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff, 787 int drop, int *nomem) 788 { 789 struct mbuf *m = *m0; 790 struct pf_frent *frp, *fra, *cur = NULL; 791 int ip_len = ntohs(h->ip_len) - (h->ip_hl << 2); 792 u_int16_t off = ntohs(h->ip_off) << 3; 793 u_int16_t max = ip_len + off; 794 int hosed = 0; 795 796 PF_FRAG_ASSERT(); 797 KASSERT((*frag == NULL || !BUFFER_FRAGMENTS(*frag)), 798 ("!(*frag == NULL || !BUFFER_FRAGMENTS(*frag)): %s", __FUNCTION__)); 799 800 /* Create a new range queue for this packet */ 801 if (*frag == NULL) { 802 *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 803 if (*frag == NULL) { 804 pf_flush_fragments(); 805 *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 806 if (*frag == NULL) 807 goto no_mem; 808 } 809 810 /* Get an entry for the queue */ 811 cur = uma_zalloc(V_pf_frent_z, M_NOWAIT); 812 if (cur == NULL) { 813 uma_zfree(V_pf_frag_z, *frag); 814 *frag = NULL; 815 goto no_mem; 816 } 817 818 (*frag)->fr_flags = PFFRAG_NOBUFFER; 819 (*frag)->fr_max = 0; 820 (*frag)->fr_src.v4 = h->ip_src; 821 (*frag)->fr_dst.v4 = h->ip_dst; 822 (*frag)->fr_af = AF_INET; 823 (*frag)->fr_proto = h->ip_p; 824 (*frag)->fr_id = h->ip_id; 825 (*frag)->fr_timeout = time_uptime; 826 827 cur->fe_off = off; 828 cur->fe_len = max; /* TODO: fe_len = max - off ? */ 829 TAILQ_INIT(&(*frag)->fr_queue); 830 TAILQ_INSERT_HEAD(&(*frag)->fr_queue, cur, fr_next); 831 832 RB_INSERT(pf_frag_tree, &V_pf_cache_tree, *frag); 833 TAILQ_INSERT_HEAD(&V_pf_cachequeue, *frag, frag_next); 834 835 DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max)); 836 837 goto pass; 838 } 839 840 /* 841 * Find a fragment after the current one: 842 * - off contains the real shifted offset. 843 */ 844 frp = NULL; 845 TAILQ_FOREACH(fra, &(*frag)->fr_queue, fr_next) { 846 if (fra->fe_off > off) 847 break; 848 frp = fra; 849 } 850 851 KASSERT((frp != NULL || fra != NULL), 852 ("!(frp != NULL || fra != NULL): %s", __FUNCTION__)); 853 854 if (frp != NULL) { 855 int precut; 856 857 precut = frp->fe_len - off; 858 if (precut >= ip_len) { 859 /* Fragment is entirely a duplicate */ 860 DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n", 861 h->ip_id, frp->fe_off, frp->fe_len, off, max)); 862 goto drop_fragment; 863 } 864 if (precut == 0) { 865 /* They are adjacent. Fixup cache entry */ 866 DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n", 867 h->ip_id, frp->fe_off, frp->fe_len, off, max)); 868 frp->fe_len = max; 869 } else if (precut > 0) { 870 /* The first part of this payload overlaps with a 871 * fragment that has already been passed. 872 * Need to trim off the first part of the payload. 873 * But to do so easily, we need to create another 874 * mbuf to throw the original header into. 875 */ 876 877 DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n", 878 h->ip_id, precut, frp->fe_off, frp->fe_len, off, 879 max)); 880 881 off += precut; 882 max -= precut; 883 /* Update the previous frag to encompass this one */ 884 frp->fe_len = max; 885 886 if (!drop) { 887 /* XXX Optimization opportunity 888 * This is a very heavy way to trim the payload. 889 * we could do it much faster by diddling mbuf 890 * internals but that would be even less legible 891 * than this mbuf magic. For my next trick, 892 * I'll pull a rabbit out of my laptop. 893 */ 894 *m0 = m_dup(m, M_NOWAIT); 895 if (*m0 == NULL) 896 goto no_mem; 897 /* From KAME Project : We have missed this! */ 898 m_adj(*m0, (h->ip_hl << 2) - 899 (*m0)->m_pkthdr.len); 900 901 KASSERT(((*m0)->m_next == NULL), 902 ("(*m0)->m_next != NULL: %s", 903 __FUNCTION__)); 904 m_adj(m, precut + (h->ip_hl << 2)); 905 m_cat(*m0, m); 906 m = *m0; 907 if (m->m_flags & M_PKTHDR) { 908 int plen = 0; 909 struct mbuf *t; 910 for (t = m; t; t = t->m_next) 911 plen += t->m_len; 912 m->m_pkthdr.len = plen; 913 } 914 915 916 h = mtod(m, struct ip *); 917 918 KASSERT(((int)m->m_len == 919 ntohs(h->ip_len) - precut), 920 ("m->m_len != ntohs(h->ip_len) - precut: %s", 921 __FUNCTION__)); 922 h->ip_off = htons(ntohs(h->ip_off) + 923 (precut >> 3)); 924 h->ip_len = htons(ntohs(h->ip_len) - precut); 925 } else { 926 hosed++; 927 } 928 } else { 929 /* There is a gap between fragments */ 930 931 DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n", 932 h->ip_id, -precut, frp->fe_off, frp->fe_len, off, 933 max)); 934 935 cur = uma_zalloc(V_pf_frent_z, M_NOWAIT); 936 if (cur == NULL) 937 goto no_mem; 938 939 cur->fe_off = off; 940 cur->fe_len = max; 941 TAILQ_INSERT_AFTER(&(*frag)->fr_queue, frp, cur, fr_next); 942 } 943 } 944 945 if (fra != NULL) { 946 int aftercut; 947 int merge = 0; 948 949 aftercut = max - fra->fe_off; 950 if (aftercut == 0) { 951 /* Adjacent fragments */ 952 DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n", 953 h->ip_id, off, max, fra->fe_off, fra->fe_len)); 954 fra->fe_off = off; 955 merge = 1; 956 } else if (aftercut > 0) { 957 /* Need to chop off the tail of this fragment */ 958 DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n", 959 h->ip_id, aftercut, off, max, fra->fe_off, 960 fra->fe_len)); 961 fra->fe_off = off; 962 max -= aftercut; 963 964 merge = 1; 965 966 if (!drop) { 967 m_adj(m, -aftercut); 968 if (m->m_flags & M_PKTHDR) { 969 int plen = 0; 970 struct mbuf *t; 971 for (t = m; t; t = t->m_next) 972 plen += t->m_len; 973 m->m_pkthdr.len = plen; 974 } 975 h = mtod(m, struct ip *); 976 KASSERT(((int)m->m_len == ntohs(h->ip_len) - aftercut), 977 ("m->m_len != ntohs(h->ip_len) - aftercut: %s", 978 __FUNCTION__)); 979 h->ip_len = htons(ntohs(h->ip_len) - aftercut); 980 } else { 981 hosed++; 982 } 983 } else if (frp == NULL) { 984 /* There is a gap between fragments */ 985 DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n", 986 h->ip_id, -aftercut, off, max, fra->fe_off, 987 fra->fe_len)); 988 989 cur = uma_zalloc(V_pf_frent_z, M_NOWAIT); 990 if (cur == NULL) 991 goto no_mem; 992 993 cur->fe_off = off; 994 cur->fe_len = max; 995 TAILQ_INSERT_HEAD(&(*frag)->fr_queue, cur, fr_next); 996 } 997 998 999 /* Need to glue together two separate fragment descriptors */ 1000 if (merge) { 1001 if (cur && fra->fe_off <= cur->fe_len) { 1002 /* Need to merge in a previous 'cur' */ 1003 DPFPRINTF(("fragcache[%d]: adjacent(merge " 1004 "%d-%d) %d-%d (%d-%d)\n", 1005 h->ip_id, cur->fe_off, cur->fe_len, off, 1006 max, fra->fe_off, fra->fe_len)); 1007 fra->fe_off = cur->fe_off; 1008 TAILQ_REMOVE(&(*frag)->fr_queue, cur, fr_next); 1009 uma_zfree(V_pf_frent_z, cur); 1010 cur = NULL; 1011 1012 } else if (frp && fra->fe_off <= frp->fe_len) { 1013 /* Need to merge in a modified 'frp' */ 1014 KASSERT((cur == NULL), ("cur != NULL: %s", 1015 __FUNCTION__)); 1016 DPFPRINTF(("fragcache[%d]: adjacent(merge " 1017 "%d-%d) %d-%d (%d-%d)\n", 1018 h->ip_id, frp->fe_off, frp->fe_len, off, 1019 max, fra->fe_off, fra->fe_len)); 1020 fra->fe_off = frp->fe_off; 1021 TAILQ_REMOVE(&(*frag)->fr_queue, frp, fr_next); 1022 uma_zfree(V_pf_frent_z, frp); 1023 frp = NULL; 1024 1025 } 1026 } 1027 } 1028 1029 if (hosed) { 1030 /* 1031 * We must keep tracking the overall fragment even when 1032 * we're going to drop it anyway so that we know when to 1033 * free the overall descriptor. Thus we drop the frag late. 1034 */ 1035 goto drop_fragment; 1036 } 1037 1038 1039 pass: 1040 /* Update maximum data size */ 1041 if ((*frag)->fr_max < max) 1042 (*frag)->fr_max = max; 1043 1044 /* This is the last segment */ 1045 if (!mff) 1046 (*frag)->fr_flags |= PFFRAG_SEENLAST; 1047 1048 /* Check if we are completely reassembled */ 1049 if (((*frag)->fr_flags & PFFRAG_SEENLAST) && 1050 TAILQ_FIRST(&(*frag)->fr_queue)->fe_off == 0 && 1051 TAILQ_FIRST(&(*frag)->fr_queue)->fe_len == (*frag)->fr_max) { 1052 /* Remove from fragment queue */ 1053 DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id, 1054 (*frag)->fr_max)); 1055 pf_free_fragment(*frag); 1056 *frag = NULL; 1057 } 1058 1059 return (m); 1060 1061 no_mem: 1062 *nomem = 1; 1063 1064 /* Still need to pay attention to !IP_MF */ 1065 if (!mff && *frag != NULL) 1066 (*frag)->fr_flags |= PFFRAG_SEENLAST; 1067 1068 m_freem(m); 1069 return (NULL); 1070 1071 drop_fragment: 1072 1073 /* Still need to pay attention to !IP_MF */ 1074 if (!mff && *frag != NULL) 1075 (*frag)->fr_flags |= PFFRAG_SEENLAST; 1076 1077 if (drop) { 1078 /* This fragment has been deemed bad. Don't reass */ 1079 if (((*frag)->fr_flags & PFFRAG_DROP) == 0) 1080 DPFPRINTF(("fragcache[%d]: dropping overall fragment\n", 1081 h->ip_id)); 1082 (*frag)->fr_flags |= PFFRAG_DROP; 1083 } 1084 1085 m_freem(m); 1086 return (NULL); 1087 } 1088 #endif /* INET */ 1089 1090 #ifdef INET6 1091 int 1092 pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag) 1093 { 1094 struct mbuf *m = *m0, *t; 1095 struct pf_fragment_tag *ftag = (struct pf_fragment_tag *)(mtag + 1); 1096 struct pf_pdesc pd; 1097 uint32_t frag_id; 1098 uint16_t hdrlen, extoff, maxlen; 1099 uint8_t proto; 1100 int error, action; 1101 1102 hdrlen = ftag->ft_hdrlen; 1103 extoff = ftag->ft_extoff; 1104 maxlen = ftag->ft_maxlen; 1105 frag_id = ftag->ft_id; 1106 m_tag_delete(m, mtag); 1107 mtag = NULL; 1108 ftag = NULL; 1109 1110 if (extoff) { 1111 int off; 1112 1113 /* Use protocol from next field of last extension header */ 1114 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt), 1115 &off); 1116 KASSERT((m != NULL), ("pf_refragment6: short mbuf chain")); 1117 proto = *(mtod(m, caddr_t) + off); 1118 *(mtod(m, char *) + off) = IPPROTO_FRAGMENT; 1119 m = *m0; 1120 } else { 1121 struct ip6_hdr *hdr; 1122 1123 hdr = mtod(m, struct ip6_hdr *); 1124 proto = hdr->ip6_nxt; 1125 hdr->ip6_nxt = IPPROTO_FRAGMENT; 1126 } 1127 1128 /* 1129 * Maxlen may be less than 8 if there was only a single 1130 * fragment. As it was fragmented before, add a fragment 1131 * header also for a single fragment. If total or maxlen 1132 * is less than 8, ip6_fragment() will return EMSGSIZE and 1133 * we drop the packet. 1134 */ 1135 error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id); 1136 m = (*m0)->m_nextpkt; 1137 (*m0)->m_nextpkt = NULL; 1138 if (error == 0) { 1139 /* The first mbuf contains the unfragmented packet. */ 1140 m_freem(*m0); 1141 *m0 = NULL; 1142 action = PF_PASS; 1143 } else { 1144 /* Drop expects an mbuf to free. */ 1145 DPFPRINTF(("refragment error %d", error)); 1146 action = PF_DROP; 1147 } 1148 for (t = m; m; m = t) { 1149 t = m->m_nextpkt; 1150 m->m_nextpkt = NULL; 1151 m->m_flags |= M_SKIP_FIREWALL; 1152 memset(&pd, 0, sizeof(pd)); 1153 pd.pf_mtag = pf_find_mtag(m); 1154 if (error == 0) 1155 ip6_forward(m, 0); 1156 else 1157 m_freem(m); 1158 } 1159 1160 return (action); 1161 } 1162 #endif /* INET6 */ 1163 1164 #ifdef INET 1165 int 1166 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason, 1167 struct pf_pdesc *pd) 1168 { 1169 struct mbuf *m = *m0; 1170 struct pf_rule *r; 1171 struct pf_fragment *frag = NULL; 1172 struct pf_fragment_cmp key; 1173 struct ip *h = mtod(m, struct ip *); 1174 int mff = (ntohs(h->ip_off) & IP_MF); 1175 int hlen = h->ip_hl << 2; 1176 u_int16_t fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3; 1177 u_int16_t max; 1178 int ip_len; 1179 int ip_off; 1180 int tag = -1; 1181 int verdict; 1182 1183 PF_RULES_RASSERT(); 1184 1185 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1186 while (r != NULL) { 1187 r->evaluations++; 1188 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1189 r = r->skip[PF_SKIP_IFP].ptr; 1190 else if (r->direction && r->direction != dir) 1191 r = r->skip[PF_SKIP_DIR].ptr; 1192 else if (r->af && r->af != AF_INET) 1193 r = r->skip[PF_SKIP_AF].ptr; 1194 else if (r->proto && r->proto != h->ip_p) 1195 r = r->skip[PF_SKIP_PROTO].ptr; 1196 else if (PF_MISMATCHAW(&r->src.addr, 1197 (struct pf_addr *)&h->ip_src.s_addr, AF_INET, 1198 r->src.neg, kif, M_GETFIB(m))) 1199 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1200 else if (PF_MISMATCHAW(&r->dst.addr, 1201 (struct pf_addr *)&h->ip_dst.s_addr, AF_INET, 1202 r->dst.neg, NULL, M_GETFIB(m))) 1203 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1204 else if (r->match_tag && !pf_match_tag(m, r, &tag, 1205 pd->pf_mtag ? pd->pf_mtag->tag : 0)) 1206 r = TAILQ_NEXT(r, entries); 1207 else 1208 break; 1209 } 1210 1211 if (r == NULL || r->action == PF_NOSCRUB) 1212 return (PF_PASS); 1213 else { 1214 r->packets[dir == PF_OUT]++; 1215 r->bytes[dir == PF_OUT] += pd->tot_len; 1216 } 1217 1218 /* Check for illegal packets */ 1219 if (hlen < (int)sizeof(struct ip)) 1220 goto drop; 1221 1222 if (hlen > ntohs(h->ip_len)) 1223 goto drop; 1224 1225 /* Clear IP_DF if the rule uses the no-df option */ 1226 if (r->rule_flag & PFRULE_NODF && h->ip_off & htons(IP_DF)) { 1227 u_int16_t ip_off = h->ip_off; 1228 1229 h->ip_off &= htons(~IP_DF); 1230 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1231 } 1232 1233 /* We will need other tests here */ 1234 if (!fragoff && !mff) 1235 goto no_fragment; 1236 1237 /* We're dealing with a fragment now. Don't allow fragments 1238 * with IP_DF to enter the cache. If the flag was cleared by 1239 * no-df above, fine. Otherwise drop it. 1240 */ 1241 if (h->ip_off & htons(IP_DF)) { 1242 DPFPRINTF(("IP_DF\n")); 1243 goto bad; 1244 } 1245 1246 ip_len = ntohs(h->ip_len) - hlen; 1247 ip_off = (ntohs(h->ip_off) & IP_OFFMASK) << 3; 1248 1249 /* All fragments are 8 byte aligned */ 1250 if (mff && (ip_len & 0x7)) { 1251 DPFPRINTF(("mff and %d\n", ip_len)); 1252 goto bad; 1253 } 1254 1255 /* Respect maximum length */ 1256 if (fragoff + ip_len > IP_MAXPACKET) { 1257 DPFPRINTF(("max packet %d\n", fragoff + ip_len)); 1258 goto bad; 1259 } 1260 max = fragoff + ip_len; 1261 1262 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) { 1263 1264 /* Fully buffer all of the fragments */ 1265 PF_FRAG_LOCK(); 1266 1267 pf_ip2key(h, dir, &key); 1268 frag = pf_find_fragment(&key, &V_pf_frag_tree); 1269 1270 /* Check if we saw the last fragment already */ 1271 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 1272 max > frag->fr_max) 1273 goto bad; 1274 1275 /* Might return a completely reassembled mbuf, or NULL */ 1276 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max)); 1277 verdict = pf_reassemble(m0, h, dir, reason); 1278 PF_FRAG_UNLOCK(); 1279 1280 if (verdict != PF_PASS) 1281 return (PF_DROP); 1282 1283 m = *m0; 1284 if (m == NULL) 1285 return (PF_DROP); 1286 1287 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP)) 1288 goto drop; 1289 1290 h = mtod(m, struct ip *); 1291 } else { 1292 /* non-buffering fragment cache (drops or masks overlaps) */ 1293 int nomem = 0; 1294 1295 if (dir == PF_OUT && pd->pf_mtag && 1296 pd->pf_mtag->flags & PF_TAG_FRAGCACHE) { 1297 /* 1298 * Already passed the fragment cache in the 1299 * input direction. If we continued, it would 1300 * appear to be a dup and would be dropped. 1301 */ 1302 goto fragment_pass; 1303 } 1304 1305 PF_FRAG_LOCK(); 1306 pf_ip2key(h, dir, &key); 1307 frag = pf_find_fragment(&key, &V_pf_cache_tree); 1308 1309 /* Check if we saw the last fragment already */ 1310 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 1311 max > frag->fr_max) { 1312 if (r->rule_flag & PFRULE_FRAGDROP) 1313 frag->fr_flags |= PFFRAG_DROP; 1314 goto bad; 1315 } 1316 1317 *m0 = m = pf_fragcache(m0, h, &frag, mff, 1318 (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem); 1319 PF_FRAG_UNLOCK(); 1320 if (m == NULL) { 1321 if (nomem) 1322 goto no_mem; 1323 goto drop; 1324 } 1325 1326 if (dir == PF_IN) { 1327 /* Use mtag from copied and trimmed mbuf chain. */ 1328 pd->pf_mtag = pf_get_mtag(m); 1329 if (pd->pf_mtag == NULL) { 1330 m_freem(m); 1331 *m0 = NULL; 1332 goto no_mem; 1333 } 1334 pd->pf_mtag->flags |= PF_TAG_FRAGCACHE; 1335 } 1336 1337 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP)) 1338 goto drop; 1339 goto fragment_pass; 1340 } 1341 1342 no_fragment: 1343 /* At this point, only IP_DF is allowed in ip_off */ 1344 if (h->ip_off & ~htons(IP_DF)) { 1345 u_int16_t ip_off = h->ip_off; 1346 1347 h->ip_off &= htons(IP_DF); 1348 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1349 } 1350 1351 /* not missing a return here */ 1352 1353 fragment_pass: 1354 pf_scrub_ip(&m, r->rule_flag, r->min_ttl, r->set_tos); 1355 1356 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) 1357 pd->flags |= PFDESC_IP_REAS; 1358 return (PF_PASS); 1359 1360 no_mem: 1361 REASON_SET(reason, PFRES_MEMORY); 1362 if (r != NULL && r->log) 1363 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd, 1364 1); 1365 return (PF_DROP); 1366 1367 drop: 1368 REASON_SET(reason, PFRES_NORM); 1369 if (r != NULL && r->log) 1370 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd, 1371 1); 1372 return (PF_DROP); 1373 1374 bad: 1375 DPFPRINTF(("dropping bad fragment\n")); 1376 1377 /* Free associated fragments */ 1378 if (frag != NULL) { 1379 pf_free_fragment(frag); 1380 PF_FRAG_UNLOCK(); 1381 } 1382 1383 REASON_SET(reason, PFRES_FRAG); 1384 if (r != NULL && r->log) 1385 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd, 1386 1); 1387 1388 return (PF_DROP); 1389 } 1390 #endif 1391 1392 #ifdef INET6 1393 int 1394 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif, 1395 u_short *reason, struct pf_pdesc *pd) 1396 { 1397 struct mbuf *m = *m0; 1398 struct pf_rule *r; 1399 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1400 int extoff; 1401 int off; 1402 struct ip6_ext ext; 1403 struct ip6_opt opt; 1404 struct ip6_opt_jumbo jumbo; 1405 struct ip6_frag frag; 1406 u_int32_t jumbolen = 0, plen; 1407 int optend; 1408 int ooff; 1409 u_int8_t proto; 1410 int terminal; 1411 1412 PF_RULES_RASSERT(); 1413 1414 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1415 while (r != NULL) { 1416 r->evaluations++; 1417 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1418 r = r->skip[PF_SKIP_IFP].ptr; 1419 else if (r->direction && r->direction != dir) 1420 r = r->skip[PF_SKIP_DIR].ptr; 1421 else if (r->af && r->af != AF_INET6) 1422 r = r->skip[PF_SKIP_AF].ptr; 1423 #if 0 /* header chain! */ 1424 else if (r->proto && r->proto != h->ip6_nxt) 1425 r = r->skip[PF_SKIP_PROTO].ptr; 1426 #endif 1427 else if (PF_MISMATCHAW(&r->src.addr, 1428 (struct pf_addr *)&h->ip6_src, AF_INET6, 1429 r->src.neg, kif, M_GETFIB(m))) 1430 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1431 else if (PF_MISMATCHAW(&r->dst.addr, 1432 (struct pf_addr *)&h->ip6_dst, AF_INET6, 1433 r->dst.neg, NULL, M_GETFIB(m))) 1434 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1435 else 1436 break; 1437 } 1438 1439 if (r == NULL || r->action == PF_NOSCRUB) 1440 return (PF_PASS); 1441 else { 1442 r->packets[dir == PF_OUT]++; 1443 r->bytes[dir == PF_OUT] += pd->tot_len; 1444 } 1445 1446 /* Check for illegal packets */ 1447 if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len) 1448 goto drop; 1449 1450 extoff = 0; 1451 off = sizeof(struct ip6_hdr); 1452 proto = h->ip6_nxt; 1453 terminal = 0; 1454 do { 1455 switch (proto) { 1456 case IPPROTO_FRAGMENT: 1457 goto fragment; 1458 break; 1459 case IPPROTO_AH: 1460 case IPPROTO_ROUTING: 1461 case IPPROTO_DSTOPTS: 1462 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1463 NULL, AF_INET6)) 1464 goto shortpkt; 1465 extoff = off; 1466 if (proto == IPPROTO_AH) 1467 off += (ext.ip6e_len + 2) * 4; 1468 else 1469 off += (ext.ip6e_len + 1) * 8; 1470 proto = ext.ip6e_nxt; 1471 break; 1472 case IPPROTO_HOPOPTS: 1473 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1474 NULL, AF_INET6)) 1475 goto shortpkt; 1476 extoff = off; 1477 optend = off + (ext.ip6e_len + 1) * 8; 1478 ooff = off + sizeof(ext); 1479 do { 1480 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type, 1481 sizeof(opt.ip6o_type), NULL, NULL, 1482 AF_INET6)) 1483 goto shortpkt; 1484 if (opt.ip6o_type == IP6OPT_PAD1) { 1485 ooff++; 1486 continue; 1487 } 1488 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt), 1489 NULL, NULL, AF_INET6)) 1490 goto shortpkt; 1491 if (ooff + sizeof(opt) + opt.ip6o_len > optend) 1492 goto drop; 1493 switch (opt.ip6o_type) { 1494 case IP6OPT_JUMBO: 1495 if (h->ip6_plen != 0) 1496 goto drop; 1497 if (!pf_pull_hdr(m, ooff, &jumbo, 1498 sizeof(jumbo), NULL, NULL, 1499 AF_INET6)) 1500 goto shortpkt; 1501 memcpy(&jumbolen, jumbo.ip6oj_jumbo_len, 1502 sizeof(jumbolen)); 1503 jumbolen = ntohl(jumbolen); 1504 if (jumbolen <= IPV6_MAXPACKET) 1505 goto drop; 1506 if (sizeof(struct ip6_hdr) + jumbolen != 1507 m->m_pkthdr.len) 1508 goto drop; 1509 break; 1510 default: 1511 break; 1512 } 1513 ooff += sizeof(opt) + opt.ip6o_len; 1514 } while (ooff < optend); 1515 1516 off = optend; 1517 proto = ext.ip6e_nxt; 1518 break; 1519 default: 1520 terminal = 1; 1521 break; 1522 } 1523 } while (!terminal); 1524 1525 /* jumbo payload option must be present, or plen > 0 */ 1526 if (ntohs(h->ip6_plen) == 0) 1527 plen = jumbolen; 1528 else 1529 plen = ntohs(h->ip6_plen); 1530 if (plen == 0) 1531 goto drop; 1532 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1533 goto shortpkt; 1534 1535 pf_scrub_ip6(&m, r->min_ttl); 1536 1537 return (PF_PASS); 1538 1539 fragment: 1540 /* Jumbo payload packets cannot be fragmented. */ 1541 plen = ntohs(h->ip6_plen); 1542 if (plen == 0 || jumbolen) 1543 goto drop; 1544 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1545 goto shortpkt; 1546 1547 if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6)) 1548 goto shortpkt; 1549 1550 /* Offset now points to data portion. */ 1551 off += sizeof(frag); 1552 1553 /* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */ 1554 if (pf_reassemble6(m0, h, &frag, off, extoff, reason) != PF_PASS) 1555 return (PF_DROP); 1556 m = *m0; 1557 if (m == NULL) 1558 return (PF_DROP); 1559 1560 pd->flags |= PFDESC_IP_REAS; 1561 return (PF_PASS); 1562 1563 shortpkt: 1564 REASON_SET(reason, PFRES_SHORT); 1565 if (r != NULL && r->log) 1566 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd, 1567 1); 1568 return (PF_DROP); 1569 1570 drop: 1571 REASON_SET(reason, PFRES_NORM); 1572 if (r != NULL && r->log) 1573 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd, 1574 1); 1575 return (PF_DROP); 1576 } 1577 #endif /* INET6 */ 1578 1579 int 1580 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff, 1581 int off, void *h, struct pf_pdesc *pd) 1582 { 1583 struct pf_rule *r, *rm = NULL; 1584 struct tcphdr *th = pd->hdr.tcp; 1585 int rewrite = 0; 1586 u_short reason; 1587 u_int8_t flags; 1588 sa_family_t af = pd->af; 1589 1590 PF_RULES_RASSERT(); 1591 1592 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1593 while (r != NULL) { 1594 r->evaluations++; 1595 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1596 r = r->skip[PF_SKIP_IFP].ptr; 1597 else if (r->direction && r->direction != dir) 1598 r = r->skip[PF_SKIP_DIR].ptr; 1599 else if (r->af && r->af != af) 1600 r = r->skip[PF_SKIP_AF].ptr; 1601 else if (r->proto && r->proto != pd->proto) 1602 r = r->skip[PF_SKIP_PROTO].ptr; 1603 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, 1604 r->src.neg, kif, M_GETFIB(m))) 1605 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1606 else if (r->src.port_op && !pf_match_port(r->src.port_op, 1607 r->src.port[0], r->src.port[1], th->th_sport)) 1608 r = r->skip[PF_SKIP_SRC_PORT].ptr; 1609 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, 1610 r->dst.neg, NULL, M_GETFIB(m))) 1611 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1612 else if (r->dst.port_op && !pf_match_port(r->dst.port_op, 1613 r->dst.port[0], r->dst.port[1], th->th_dport)) 1614 r = r->skip[PF_SKIP_DST_PORT].ptr; 1615 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match( 1616 pf_osfp_fingerprint(pd, m, off, th), 1617 r->os_fingerprint)) 1618 r = TAILQ_NEXT(r, entries); 1619 else { 1620 rm = r; 1621 break; 1622 } 1623 } 1624 1625 if (rm == NULL || rm->action == PF_NOSCRUB) 1626 return (PF_PASS); 1627 else { 1628 r->packets[dir == PF_OUT]++; 1629 r->bytes[dir == PF_OUT] += pd->tot_len; 1630 } 1631 1632 if (rm->rule_flag & PFRULE_REASSEMBLE_TCP) 1633 pd->flags |= PFDESC_TCP_NORM; 1634 1635 flags = th->th_flags; 1636 if (flags & TH_SYN) { 1637 /* Illegal packet */ 1638 if (flags & TH_RST) 1639 goto tcp_drop; 1640 1641 if (flags & TH_FIN) 1642 goto tcp_drop; 1643 } else { 1644 /* Illegal packet */ 1645 if (!(flags & (TH_ACK|TH_RST))) 1646 goto tcp_drop; 1647 } 1648 1649 if (!(flags & TH_ACK)) { 1650 /* These flags are only valid if ACK is set */ 1651 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG)) 1652 goto tcp_drop; 1653 } 1654 1655 /* Check for illegal header length */ 1656 if (th->th_off < (sizeof(struct tcphdr) >> 2)) 1657 goto tcp_drop; 1658 1659 /* If flags changed, or reserved data set, then adjust */ 1660 if (flags != th->th_flags || th->th_x2 != 0) { 1661 u_int16_t ov, nv; 1662 1663 ov = *(u_int16_t *)(&th->th_ack + 1); 1664 th->th_flags = flags; 1665 th->th_x2 = 0; 1666 nv = *(u_int16_t *)(&th->th_ack + 1); 1667 1668 th->th_sum = pf_cksum_fixup(th->th_sum, ov, nv, 0); 1669 rewrite = 1; 1670 } 1671 1672 /* Remove urgent pointer, if TH_URG is not set */ 1673 if (!(flags & TH_URG) && th->th_urp) { 1674 th->th_sum = pf_cksum_fixup(th->th_sum, th->th_urp, 0, 0); 1675 th->th_urp = 0; 1676 rewrite = 1; 1677 } 1678 1679 /* Process options */ 1680 if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af)) 1681 rewrite = 1; 1682 1683 /* copy back packet headers if we sanitized */ 1684 if (rewrite) 1685 m_copyback(m, off, sizeof(*th), (caddr_t)th); 1686 1687 return (PF_PASS); 1688 1689 tcp_drop: 1690 REASON_SET(&reason, PFRES_NORM); 1691 if (rm != NULL && r->log) 1692 PFLOG_PACKET(kif, m, AF_INET, dir, reason, r, NULL, NULL, pd, 1693 1); 1694 return (PF_DROP); 1695 } 1696 1697 int 1698 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd, 1699 struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst) 1700 { 1701 u_int32_t tsval, tsecr; 1702 u_int8_t hdr[60]; 1703 u_int8_t *opt; 1704 1705 KASSERT((src->scrub == NULL), 1706 ("pf_normalize_tcp_init: src->scrub != NULL")); 1707 1708 src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT); 1709 if (src->scrub == NULL) 1710 return (1); 1711 1712 switch (pd->af) { 1713 #ifdef INET 1714 case AF_INET: { 1715 struct ip *h = mtod(m, struct ip *); 1716 src->scrub->pfss_ttl = h->ip_ttl; 1717 break; 1718 } 1719 #endif /* INET */ 1720 #ifdef INET6 1721 case AF_INET6: { 1722 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1723 src->scrub->pfss_ttl = h->ip6_hlim; 1724 break; 1725 } 1726 #endif /* INET6 */ 1727 } 1728 1729 1730 /* 1731 * All normalizations below are only begun if we see the start of 1732 * the connections. They must all set an enabled bit in pfss_flags 1733 */ 1734 if ((th->th_flags & TH_SYN) == 0) 1735 return (0); 1736 1737 1738 if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub && 1739 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1740 /* Diddle with TCP options */ 1741 int hlen; 1742 opt = hdr + sizeof(struct tcphdr); 1743 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1744 while (hlen >= TCPOLEN_TIMESTAMP) { 1745 switch (*opt) { 1746 case TCPOPT_EOL: /* FALLTHROUGH */ 1747 case TCPOPT_NOP: 1748 opt++; 1749 hlen--; 1750 break; 1751 case TCPOPT_TIMESTAMP: 1752 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1753 src->scrub->pfss_flags |= 1754 PFSS_TIMESTAMP; 1755 src->scrub->pfss_ts_mod = 1756 htonl(arc4random()); 1757 1758 /* note PFSS_PAWS not set yet */ 1759 memcpy(&tsval, &opt[2], 1760 sizeof(u_int32_t)); 1761 memcpy(&tsecr, &opt[6], 1762 sizeof(u_int32_t)); 1763 src->scrub->pfss_tsval0 = ntohl(tsval); 1764 src->scrub->pfss_tsval = ntohl(tsval); 1765 src->scrub->pfss_tsecr = ntohl(tsecr); 1766 getmicrouptime(&src->scrub->pfss_last); 1767 } 1768 /* FALLTHROUGH */ 1769 default: 1770 hlen -= MAX(opt[1], 2); 1771 opt += MAX(opt[1], 2); 1772 break; 1773 } 1774 } 1775 } 1776 1777 return (0); 1778 } 1779 1780 void 1781 pf_normalize_tcp_cleanup(struct pf_state *state) 1782 { 1783 if (state->src.scrub) 1784 uma_zfree(V_pf_state_scrub_z, state->src.scrub); 1785 if (state->dst.scrub) 1786 uma_zfree(V_pf_state_scrub_z, state->dst.scrub); 1787 1788 /* Someday... flush the TCP segment reassembly descriptors. */ 1789 } 1790 1791 int 1792 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd, 1793 u_short *reason, struct tcphdr *th, struct pf_state *state, 1794 struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback) 1795 { 1796 struct timeval uptime; 1797 u_int32_t tsval, tsecr; 1798 u_int tsval_from_last; 1799 u_int8_t hdr[60]; 1800 u_int8_t *opt; 1801 int copyback = 0; 1802 int got_ts = 0; 1803 1804 KASSERT((src->scrub || dst->scrub), 1805 ("%s: src->scrub && dst->scrub!", __func__)); 1806 1807 /* 1808 * Enforce the minimum TTL seen for this connection. Negate a common 1809 * technique to evade an intrusion detection system and confuse 1810 * firewall state code. 1811 */ 1812 switch (pd->af) { 1813 #ifdef INET 1814 case AF_INET: { 1815 if (src->scrub) { 1816 struct ip *h = mtod(m, struct ip *); 1817 if (h->ip_ttl > src->scrub->pfss_ttl) 1818 src->scrub->pfss_ttl = h->ip_ttl; 1819 h->ip_ttl = src->scrub->pfss_ttl; 1820 } 1821 break; 1822 } 1823 #endif /* INET */ 1824 #ifdef INET6 1825 case AF_INET6: { 1826 if (src->scrub) { 1827 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1828 if (h->ip6_hlim > src->scrub->pfss_ttl) 1829 src->scrub->pfss_ttl = h->ip6_hlim; 1830 h->ip6_hlim = src->scrub->pfss_ttl; 1831 } 1832 break; 1833 } 1834 #endif /* INET6 */ 1835 } 1836 1837 if (th->th_off > (sizeof(struct tcphdr) >> 2) && 1838 ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) || 1839 (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) && 1840 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1841 /* Diddle with TCP options */ 1842 int hlen; 1843 opt = hdr + sizeof(struct tcphdr); 1844 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1845 while (hlen >= TCPOLEN_TIMESTAMP) { 1846 switch (*opt) { 1847 case TCPOPT_EOL: /* FALLTHROUGH */ 1848 case TCPOPT_NOP: 1849 opt++; 1850 hlen--; 1851 break; 1852 case TCPOPT_TIMESTAMP: 1853 /* Modulate the timestamps. Can be used for 1854 * NAT detection, OS uptime determination or 1855 * reboot detection. 1856 */ 1857 1858 if (got_ts) { 1859 /* Huh? Multiple timestamps!? */ 1860 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1861 DPFPRINTF(("multiple TS??")); 1862 pf_print_state(state); 1863 printf("\n"); 1864 } 1865 REASON_SET(reason, PFRES_TS); 1866 return (PF_DROP); 1867 } 1868 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1869 memcpy(&tsval, &opt[2], 1870 sizeof(u_int32_t)); 1871 if (tsval && src->scrub && 1872 (src->scrub->pfss_flags & 1873 PFSS_TIMESTAMP)) { 1874 tsval = ntohl(tsval); 1875 pf_change_a(&opt[2], 1876 &th->th_sum, 1877 htonl(tsval + 1878 src->scrub->pfss_ts_mod), 1879 0); 1880 copyback = 1; 1881 } 1882 1883 /* Modulate TS reply iff valid (!0) */ 1884 memcpy(&tsecr, &opt[6], 1885 sizeof(u_int32_t)); 1886 if (tsecr && dst->scrub && 1887 (dst->scrub->pfss_flags & 1888 PFSS_TIMESTAMP)) { 1889 tsecr = ntohl(tsecr) 1890 - dst->scrub->pfss_ts_mod; 1891 pf_change_a(&opt[6], 1892 &th->th_sum, htonl(tsecr), 1893 0); 1894 copyback = 1; 1895 } 1896 got_ts = 1; 1897 } 1898 /* FALLTHROUGH */ 1899 default: 1900 hlen -= MAX(opt[1], 2); 1901 opt += MAX(opt[1], 2); 1902 break; 1903 } 1904 } 1905 if (copyback) { 1906 /* Copyback the options, caller copys back header */ 1907 *writeback = 1; 1908 m_copyback(m, off + sizeof(struct tcphdr), 1909 (th->th_off << 2) - sizeof(struct tcphdr), hdr + 1910 sizeof(struct tcphdr)); 1911 } 1912 } 1913 1914 1915 /* 1916 * Must invalidate PAWS checks on connections idle for too long. 1917 * The fastest allowed timestamp clock is 1ms. That turns out to 1918 * be about 24 days before it wraps. XXX Right now our lowerbound 1919 * TS echo check only works for the first 12 days of a connection 1920 * when the TS has exhausted half its 32bit space 1921 */ 1922 #define TS_MAX_IDLE (24*24*60*60) 1923 #define TS_MAX_CONN (12*24*60*60) /* XXX remove when better tsecr check */ 1924 1925 getmicrouptime(&uptime); 1926 if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) && 1927 (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE || 1928 time_uptime - state->creation > TS_MAX_CONN)) { 1929 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1930 DPFPRINTF(("src idled out of PAWS\n")); 1931 pf_print_state(state); 1932 printf("\n"); 1933 } 1934 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS) 1935 | PFSS_PAWS_IDLED; 1936 } 1937 if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) && 1938 uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) { 1939 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1940 DPFPRINTF(("dst idled out of PAWS\n")); 1941 pf_print_state(state); 1942 printf("\n"); 1943 } 1944 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS) 1945 | PFSS_PAWS_IDLED; 1946 } 1947 1948 if (got_ts && src->scrub && dst->scrub && 1949 (src->scrub->pfss_flags & PFSS_PAWS) && 1950 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1951 /* Validate that the timestamps are "in-window". 1952 * RFC1323 describes TCP Timestamp options that allow 1953 * measurement of RTT (round trip time) and PAWS 1954 * (protection against wrapped sequence numbers). PAWS 1955 * gives us a set of rules for rejecting packets on 1956 * long fat pipes (packets that were somehow delayed 1957 * in transit longer than the time it took to send the 1958 * full TCP sequence space of 4Gb). We can use these 1959 * rules and infer a few others that will let us treat 1960 * the 32bit timestamp and the 32bit echoed timestamp 1961 * as sequence numbers to prevent a blind attacker from 1962 * inserting packets into a connection. 1963 * 1964 * RFC1323 tells us: 1965 * - The timestamp on this packet must be greater than 1966 * or equal to the last value echoed by the other 1967 * endpoint. The RFC says those will be discarded 1968 * since it is a dup that has already been acked. 1969 * This gives us a lowerbound on the timestamp. 1970 * timestamp >= other last echoed timestamp 1971 * - The timestamp will be less than or equal to 1972 * the last timestamp plus the time between the 1973 * last packet and now. The RFC defines the max 1974 * clock rate as 1ms. We will allow clocks to be 1975 * up to 10% fast and will allow a total difference 1976 * or 30 seconds due to a route change. And this 1977 * gives us an upperbound on the timestamp. 1978 * timestamp <= last timestamp + max ticks 1979 * We have to be careful here. Windows will send an 1980 * initial timestamp of zero and then initialize it 1981 * to a random value after the 3whs; presumably to 1982 * avoid a DoS by having to call an expensive RNG 1983 * during a SYN flood. Proof MS has at least one 1984 * good security geek. 1985 * 1986 * - The TCP timestamp option must also echo the other 1987 * endpoints timestamp. The timestamp echoed is the 1988 * one carried on the earliest unacknowledged segment 1989 * on the left edge of the sequence window. The RFC 1990 * states that the host will reject any echoed 1991 * timestamps that were larger than any ever sent. 1992 * This gives us an upperbound on the TS echo. 1993 * tescr <= largest_tsval 1994 * - The lowerbound on the TS echo is a little more 1995 * tricky to determine. The other endpoint's echoed 1996 * values will not decrease. But there may be 1997 * network conditions that re-order packets and 1998 * cause our view of them to decrease. For now the 1999 * only lowerbound we can safely determine is that 2000 * the TS echo will never be less than the original 2001 * TS. XXX There is probably a better lowerbound. 2002 * Remove TS_MAX_CONN with better lowerbound check. 2003 * tescr >= other original TS 2004 * 2005 * It is also important to note that the fastest 2006 * timestamp clock of 1ms will wrap its 32bit space in 2007 * 24 days. So we just disable TS checking after 24 2008 * days of idle time. We actually must use a 12d 2009 * connection limit until we can come up with a better 2010 * lowerbound to the TS echo check. 2011 */ 2012 struct timeval delta_ts; 2013 int ts_fudge; 2014 2015 2016 /* 2017 * PFTM_TS_DIFF is how many seconds of leeway to allow 2018 * a host's timestamp. This can happen if the previous 2019 * packet got delayed in transit for much longer than 2020 * this packet. 2021 */ 2022 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0) 2023 ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF]; 2024 2025 /* Calculate max ticks since the last timestamp */ 2026 #define TS_MAXFREQ 1100 /* RFC max TS freq of 1Khz + 10% skew */ 2027 #define TS_MICROSECS 1000000 /* microseconds per second */ 2028 delta_ts = uptime; 2029 timevalsub(&delta_ts, &src->scrub->pfss_last); 2030 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ; 2031 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ); 2032 2033 if ((src->state >= TCPS_ESTABLISHED && 2034 dst->state >= TCPS_ESTABLISHED) && 2035 (SEQ_LT(tsval, dst->scrub->pfss_tsecr) || 2036 SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) || 2037 (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) || 2038 SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) { 2039 /* Bad RFC1323 implementation or an insertion attack. 2040 * 2041 * - Solaris 2.6 and 2.7 are known to send another ACK 2042 * after the FIN,FIN|ACK,ACK closing that carries 2043 * an old timestamp. 2044 */ 2045 2046 DPFPRINTF(("Timestamp failed %c%c%c%c\n", 2047 SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ', 2048 SEQ_GT(tsval, src->scrub->pfss_tsval + 2049 tsval_from_last) ? '1' : ' ', 2050 SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ', 2051 SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' ')); 2052 DPFPRINTF((" tsval: %u tsecr: %u +ticks: %u " 2053 "idle: %jus %lums\n", 2054 tsval, tsecr, tsval_from_last, 2055 (uintmax_t)delta_ts.tv_sec, 2056 delta_ts.tv_usec / 1000)); 2057 DPFPRINTF((" src->tsval: %u tsecr: %u\n", 2058 src->scrub->pfss_tsval, src->scrub->pfss_tsecr)); 2059 DPFPRINTF((" dst->tsval: %u tsecr: %u tsval0: %u" 2060 "\n", dst->scrub->pfss_tsval, 2061 dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0)); 2062 if (V_pf_status.debug >= PF_DEBUG_MISC) { 2063 pf_print_state(state); 2064 pf_print_flags(th->th_flags); 2065 printf("\n"); 2066 } 2067 REASON_SET(reason, PFRES_TS); 2068 return (PF_DROP); 2069 } 2070 2071 /* XXX I'd really like to require tsecr but it's optional */ 2072 2073 } else if (!got_ts && (th->th_flags & TH_RST) == 0 && 2074 ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED) 2075 || pd->p_len > 0 || (th->th_flags & TH_SYN)) && 2076 src->scrub && dst->scrub && 2077 (src->scrub->pfss_flags & PFSS_PAWS) && 2078 (dst->scrub->pfss_flags & PFSS_PAWS)) { 2079 /* Didn't send a timestamp. Timestamps aren't really useful 2080 * when: 2081 * - connection opening or closing (often not even sent). 2082 * but we must not let an attacker to put a FIN on a 2083 * data packet to sneak it through our ESTABLISHED check. 2084 * - on a TCP reset. RFC suggests not even looking at TS. 2085 * - on an empty ACK. The TS will not be echoed so it will 2086 * probably not help keep the RTT calculation in sync and 2087 * there isn't as much danger when the sequence numbers 2088 * got wrapped. So some stacks don't include TS on empty 2089 * ACKs :-( 2090 * 2091 * To minimize the disruption to mostly RFC1323 conformant 2092 * stacks, we will only require timestamps on data packets. 2093 * 2094 * And what do ya know, we cannot require timestamps on data 2095 * packets. There appear to be devices that do legitimate 2096 * TCP connection hijacking. There are HTTP devices that allow 2097 * a 3whs (with timestamps) and then buffer the HTTP request. 2098 * If the intermediate device has the HTTP response cache, it 2099 * will spoof the response but not bother timestamping its 2100 * packets. So we can look for the presence of a timestamp in 2101 * the first data packet and if there, require it in all future 2102 * packets. 2103 */ 2104 2105 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) { 2106 /* 2107 * Hey! Someone tried to sneak a packet in. Or the 2108 * stack changed its RFC1323 behavior?!?! 2109 */ 2110 if (V_pf_status.debug >= PF_DEBUG_MISC) { 2111 DPFPRINTF(("Did not receive expected RFC1323 " 2112 "timestamp\n")); 2113 pf_print_state(state); 2114 pf_print_flags(th->th_flags); 2115 printf("\n"); 2116 } 2117 REASON_SET(reason, PFRES_TS); 2118 return (PF_DROP); 2119 } 2120 } 2121 2122 2123 /* 2124 * We will note if a host sends his data packets with or without 2125 * timestamps. And require all data packets to contain a timestamp 2126 * if the first does. PAWS implicitly requires that all data packets be 2127 * timestamped. But I think there are middle-man devices that hijack 2128 * TCP streams immediately after the 3whs and don't timestamp their 2129 * packets (seen in a WWW accelerator or cache). 2130 */ 2131 if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags & 2132 (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) { 2133 if (got_ts) 2134 src->scrub->pfss_flags |= PFSS_DATA_TS; 2135 else { 2136 src->scrub->pfss_flags |= PFSS_DATA_NOTS; 2137 if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub && 2138 (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) { 2139 /* Don't warn if other host rejected RFC1323 */ 2140 DPFPRINTF(("Broken RFC1323 stack did not " 2141 "timestamp data packet. Disabled PAWS " 2142 "security.\n")); 2143 pf_print_state(state); 2144 pf_print_flags(th->th_flags); 2145 printf("\n"); 2146 } 2147 } 2148 } 2149 2150 2151 /* 2152 * Update PAWS values 2153 */ 2154 if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags & 2155 (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) { 2156 getmicrouptime(&src->scrub->pfss_last); 2157 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) || 2158 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 2159 src->scrub->pfss_tsval = tsval; 2160 2161 if (tsecr) { 2162 if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) || 2163 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 2164 src->scrub->pfss_tsecr = tsecr; 2165 2166 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 && 2167 (SEQ_LT(tsval, src->scrub->pfss_tsval0) || 2168 src->scrub->pfss_tsval0 == 0)) { 2169 /* tsval0 MUST be the lowest timestamp */ 2170 src->scrub->pfss_tsval0 = tsval; 2171 } 2172 2173 /* Only fully initialized after a TS gets echoed */ 2174 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0) 2175 src->scrub->pfss_flags |= PFSS_PAWS; 2176 } 2177 } 2178 2179 /* I have a dream.... TCP segment reassembly.... */ 2180 return (0); 2181 } 2182 2183 static int 2184 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th, 2185 int off, sa_family_t af) 2186 { 2187 u_int16_t *mss; 2188 int thoff; 2189 int opt, cnt, optlen = 0; 2190 int rewrite = 0; 2191 u_char opts[TCP_MAXOLEN]; 2192 u_char *optp = opts; 2193 2194 thoff = th->th_off << 2; 2195 cnt = thoff - sizeof(struct tcphdr); 2196 2197 if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt, 2198 NULL, NULL, af)) 2199 return (rewrite); 2200 2201 for (; cnt > 0; cnt -= optlen, optp += optlen) { 2202 opt = optp[0]; 2203 if (opt == TCPOPT_EOL) 2204 break; 2205 if (opt == TCPOPT_NOP) 2206 optlen = 1; 2207 else { 2208 if (cnt < 2) 2209 break; 2210 optlen = optp[1]; 2211 if (optlen < 2 || optlen > cnt) 2212 break; 2213 } 2214 switch (opt) { 2215 case TCPOPT_MAXSEG: 2216 mss = (u_int16_t *)(optp + 2); 2217 if ((ntohs(*mss)) > r->max_mss) { 2218 th->th_sum = pf_cksum_fixup(th->th_sum, 2219 *mss, htons(r->max_mss), 0); 2220 *mss = htons(r->max_mss); 2221 rewrite = 1; 2222 } 2223 break; 2224 default: 2225 break; 2226 } 2227 } 2228 2229 if (rewrite) 2230 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts); 2231 2232 return (rewrite); 2233 } 2234 2235 #ifdef INET 2236 static void 2237 pf_scrub_ip(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos) 2238 { 2239 struct mbuf *m = *m0; 2240 struct ip *h = mtod(m, struct ip *); 2241 2242 /* Clear IP_DF if no-df was requested */ 2243 if (flags & PFRULE_NODF && h->ip_off & htons(IP_DF)) { 2244 u_int16_t ip_off = h->ip_off; 2245 2246 h->ip_off &= htons(~IP_DF); 2247 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 2248 } 2249 2250 /* Enforce a minimum ttl, may cause endless packet loops */ 2251 if (min_ttl && h->ip_ttl < min_ttl) { 2252 u_int16_t ip_ttl = h->ip_ttl; 2253 2254 h->ip_ttl = min_ttl; 2255 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0); 2256 } 2257 2258 /* Enforce tos */ 2259 if (flags & PFRULE_SET_TOS) { 2260 u_int16_t ov, nv; 2261 2262 ov = *(u_int16_t *)h; 2263 h->ip_tos = tos; 2264 nv = *(u_int16_t *)h; 2265 2266 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0); 2267 } 2268 2269 /* random-id, but not for fragments */ 2270 if (flags & PFRULE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) { 2271 uint16_t ip_id = h->ip_id; 2272 2273 ip_fillid(h); 2274 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0); 2275 } 2276 } 2277 #endif /* INET */ 2278 2279 #ifdef INET6 2280 static void 2281 pf_scrub_ip6(struct mbuf **m0, u_int8_t min_ttl) 2282 { 2283 struct mbuf *m = *m0; 2284 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 2285 2286 /* Enforce a minimum ttl, may cause endless packet loops */ 2287 if (min_ttl && h->ip6_hlim < min_ttl) 2288 h->ip6_hlim = min_ttl; 2289 } 2290 #endif 2291