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: stable/10/sys/netpfil/pf/pf_norm.c 338106 2018-08-20 15:43:08Z kp $"); 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/lock.h> 38#include <sys/mbuf.h> 39#include <sys/mutex.h> 40#include <sys/refcount.h> 41#include <sys/rwlock.h> 42#include <sys/socket.h> 43 44#include <net/if.h> 45#include <net/vnet.h> 46#include <net/pfvar.h> 47#include <net/if_pflog.h> 48 49#include <netinet/in.h> 50#include <netinet/ip.h> 51#include <netinet/ip_var.h> 52#include <netinet6/ip6_var.h> 53#include <netinet/tcp.h> 54#include <netinet/tcp_fsm.h> 55#include <netinet/tcp_seq.h> 56 57#ifdef INET6 58#include <netinet/ip6.h> 59#endif /* INET6 */ 60 61struct pf_frent { 62 TAILQ_ENTRY(pf_frent) fr_next; 63 struct mbuf *fe_m; 64 uint16_t fe_hdrlen; /* ipv4 header lenght with ip options 65 ipv6, extension, fragment header */ 66 uint16_t fe_extoff; /* last extension header offset or 0 */ 67 uint16_t fe_len; /* fragment length */ 68 uint16_t fe_off; /* fragment offset */ 69 uint16_t fe_mff; /* more fragment flag */ 70}; 71 72struct pf_fragment_cmp { 73 struct pf_addr frc_src; 74 struct pf_addr frc_dst; 75 uint32_t frc_id; 76 sa_family_t frc_af; 77 uint8_t frc_proto; 78}; 79 80struct pf_fragment { 81 struct pf_fragment_cmp fr_key; 82#define fr_src fr_key.frc_src 83#define fr_dst fr_key.frc_dst 84#define fr_id fr_key.frc_id 85#define fr_af fr_key.frc_af 86#define fr_proto fr_key.frc_proto 87 88 RB_ENTRY(pf_fragment) fr_entry; 89 TAILQ_ENTRY(pf_fragment) frag_next; 90 uint8_t fr_flags; /* status flags */ 91#define PFFRAG_SEENLAST 0x0001 /* Seen the last fragment for this */ 92#define PFFRAG_NOBUFFER 0x0002 /* Non-buffering fragment cache */ 93#define PFFRAG_DROP 0x0004 /* Drop all fragments */ 94#define BUFFER_FRAGMENTS(fr) (!((fr)->fr_flags & PFFRAG_NOBUFFER)) 95 uint16_t fr_max; /* fragment data max */ 96 uint32_t fr_timeout; 97 uint16_t fr_maxlen; /* maximum length of single fragment */ 98 uint16_t fr_entries; /* Total number of pf_fragment entries */ 99 TAILQ_HEAD(pf_fragq, pf_frent) fr_queue; 100}; 101#define PF_MAX_FRENT_PER_FRAGMENT 64 102 103struct pf_fragment_tag { 104 uint16_t ft_hdrlen; /* header length of reassembled pkt */ 105 uint16_t ft_extoff; /* last extension header offset or 0 */ 106 uint16_t ft_maxlen; /* maximum fragment payload length */ 107 uint32_t ft_id; /* fragment id */ 108}; 109 110static struct mtx pf_frag_mtx; 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 115VNET_DEFINE(uma_zone_t, pf_state_scrub_z); /* XXX: shared with pfsync */ 116 117static VNET_DEFINE(uma_zone_t, pf_frent_z); 118#define V_pf_frent_z VNET(pf_frent_z) 119static VNET_DEFINE(uma_zone_t, pf_frag_z); 120#define V_pf_frag_z VNET(pf_frag_z) 121 122TAILQ_HEAD(pf_fragqueue, pf_fragment); 123TAILQ_HEAD(pf_cachequeue, pf_fragment); 124static VNET_DEFINE(struct pf_fragqueue, pf_fragqueue); 125#define V_pf_fragqueue VNET(pf_fragqueue) 126static VNET_DEFINE(struct pf_cachequeue, pf_cachequeue); 127#define V_pf_cachequeue VNET(pf_cachequeue) 128RB_HEAD(pf_frag_tree, pf_fragment); 129static VNET_DEFINE(struct pf_frag_tree, pf_frag_tree); 130#define V_pf_frag_tree VNET(pf_frag_tree) 131static VNET_DEFINE(struct pf_frag_tree, pf_cache_tree); 132#define V_pf_cache_tree VNET(pf_cache_tree) 133static int pf_frag_compare(struct pf_fragment *, 134 struct pf_fragment *); 135static RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 136static RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare); 137 138static void pf_flush_fragments(void); 139static void pf_free_fragment(struct pf_fragment *); 140static void pf_remove_fragment(struct pf_fragment *); 141static int pf_normalize_tcpopt(struct pf_rule *, struct mbuf *, 142 struct tcphdr *, int, sa_family_t); 143static struct pf_frent *pf_create_fragment(u_short *); 144static struct pf_fragment *pf_find_fragment(struct pf_fragment_cmp *key, 145 struct pf_frag_tree *tree); 146static struct pf_fragment *pf_fillup_fragment(struct pf_fragment_cmp *, 147 struct pf_frent *, u_short *); 148static int pf_isfull_fragment(struct pf_fragment *); 149static struct mbuf *pf_join_fragment(struct pf_fragment *); 150#ifdef INET 151static void pf_scrub_ip(struct mbuf **, uint32_t, uint8_t, uint8_t); 152static int pf_reassemble(struct mbuf **, struct ip *, int, u_short *); 153static struct mbuf *pf_fragcache(struct mbuf **, struct ip*, 154 struct pf_fragment **, int, int, int *); 155#endif /* INET */ 156#ifdef INET6 157static int pf_reassemble6(struct mbuf **, struct ip6_hdr *, 158 struct ip6_frag *, uint16_t, uint16_t, u_short *); 159static 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 170static void 171pf_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 182void 183pf_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 mtx_init(&pf_frag_mtx, "pf fragments", NULL, MTX_DEF); 200 201 TAILQ_INIT(&V_pf_fragqueue); 202 TAILQ_INIT(&V_pf_cachequeue); 203} 204 205void 206pf_normalize_cleanup(void) 207{ 208 209 uma_zdestroy(V_pf_state_scrub_z); 210 uma_zdestroy(V_pf_frent_z); 211 uma_zdestroy(V_pf_frag_z); 212 213 mtx_destroy(&pf_frag_mtx); 214} 215 216static int 217pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b) 218{ 219 int diff; 220 221 if ((diff = a->fr_id - b->fr_id) != 0) 222 return (diff); 223 if ((diff = a->fr_proto - b->fr_proto) != 0) 224 return (diff); 225 if ((diff = a->fr_af - b->fr_af) != 0) 226 return (diff); 227 if ((diff = pf_addr_cmp(&a->fr_src, &b->fr_src, a->fr_af)) != 0) 228 return (diff); 229 if ((diff = pf_addr_cmp(&a->fr_dst, &b->fr_dst, a->fr_af)) != 0) 230 return (diff); 231 return (0); 232} 233 234void 235pf_purge_expired_fragments(void) 236{ 237 struct pf_fragment *frag; 238 u_int32_t expire = time_uptime - 239 V_pf_default_rule.timeout[PFTM_FRAG]; 240 241 PF_FRAG_LOCK(); 242 while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) { 243 KASSERT((BUFFER_FRAGMENTS(frag)), 244 ("BUFFER_FRAGMENTS(frag) == 0: %s", __FUNCTION__)); 245 if (frag->fr_timeout > expire) 246 break; 247 248 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); 249 pf_free_fragment(frag); 250 } 251 252 while ((frag = TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue)) != NULL) { 253 KASSERT((!BUFFER_FRAGMENTS(frag)), 254 ("BUFFER_FRAGMENTS(frag) != 0: %s", __FUNCTION__)); 255 if (frag->fr_timeout > expire) 256 break; 257 258 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); 259 pf_free_fragment(frag); 260 KASSERT((TAILQ_EMPTY(&V_pf_cachequeue) || 261 TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue) != frag), 262 ("!(TAILQ_EMPTY() || TAILQ_LAST() == farg): %s", 263 __FUNCTION__)); 264 } 265 PF_FRAG_UNLOCK(); 266} 267 268/* 269 * Try to flush old fragments to make space for new ones 270 */ 271static void 272pf_flush_fragments(void) 273{ 274 struct pf_fragment *frag, *cache; 275 int goal; 276 277 PF_FRAG_ASSERT(); 278 279 goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10; 280 DPFPRINTF(("trying to free %d frag entriess\n", goal)); 281 while (goal < uma_zone_get_cur(V_pf_frent_z)) { 282 frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue); 283 if (frag) 284 pf_free_fragment(frag); 285 cache = TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue); 286 if (cache) 287 pf_free_fragment(cache); 288 if (frag == NULL && cache == NULL) 289 break; 290 } 291} 292 293/* Frees the fragments and all associated entries */ 294static void 295pf_free_fragment(struct pf_fragment *frag) 296{ 297 struct pf_frent *frent; 298 299 PF_FRAG_ASSERT(); 300 301 /* Free all fragments */ 302 if (BUFFER_FRAGMENTS(frag)) { 303 for (frent = TAILQ_FIRST(&frag->fr_queue); frent; 304 frent = TAILQ_FIRST(&frag->fr_queue)) { 305 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 306 307 m_freem(frent->fe_m); 308 uma_zfree(V_pf_frent_z, frent); 309 } 310 } else { 311 for (frent = TAILQ_FIRST(&frag->fr_queue); frent; 312 frent = TAILQ_FIRST(&frag->fr_queue)) { 313 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 314 315 KASSERT((TAILQ_EMPTY(&frag->fr_queue) || 316 TAILQ_FIRST(&frag->fr_queue)->fe_off > 317 frent->fe_len), 318 ("! (TAILQ_EMPTY() || TAILQ_FIRST()->fe_off >" 319 " frent->fe_len): %s", __func__)); 320 321 uma_zfree(V_pf_frent_z, frent); 322 } 323 } 324 325 pf_remove_fragment(frag); 326} 327 328static struct pf_fragment * 329pf_find_fragment(struct pf_fragment_cmp *key, struct pf_frag_tree *tree) 330{ 331 struct pf_fragment *frag; 332 333 PF_FRAG_ASSERT(); 334 335 frag = RB_FIND(pf_frag_tree, tree, (struct pf_fragment *)key); 336 if (frag != NULL) { 337 /* XXX Are we sure we want to update the timeout? */ 338 frag->fr_timeout = time_uptime; 339 if (BUFFER_FRAGMENTS(frag)) { 340 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next); 341 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next); 342 } else { 343 TAILQ_REMOVE(&V_pf_cachequeue, frag, frag_next); 344 TAILQ_INSERT_HEAD(&V_pf_cachequeue, frag, frag_next); 345 } 346 } 347 348 return (frag); 349} 350 351/* Removes a fragment from the fragment queue and frees the fragment */ 352static void 353pf_remove_fragment(struct pf_fragment *frag) 354{ 355 356 PF_FRAG_ASSERT(); 357 358 if (BUFFER_FRAGMENTS(frag)) { 359 RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag); 360 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next); 361 uma_zfree(V_pf_frag_z, frag); 362 } else { 363 RB_REMOVE(pf_frag_tree, &V_pf_cache_tree, frag); 364 TAILQ_REMOVE(&V_pf_cachequeue, frag, frag_next); 365 uma_zfree(V_pf_frag_z, frag); 366 } 367} 368 369static struct pf_frent * 370pf_create_fragment(u_short *reason) 371{ 372 struct pf_frent *frent; 373 374 PF_FRAG_ASSERT(); 375 376 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT); 377 if (frent == NULL) { 378 pf_flush_fragments(); 379 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT); 380 if (frent == NULL) { 381 REASON_SET(reason, PFRES_MEMORY); 382 return (NULL); 383 } 384 } 385 386 return (frent); 387} 388 389struct pf_fragment * 390pf_fillup_fragment(struct pf_fragment_cmp *key, struct pf_frent *frent, 391 u_short *reason) 392{ 393 struct pf_frent *after, *next, *prev; 394 struct pf_fragment *frag; 395 uint16_t total; 396 397 PF_FRAG_ASSERT(); 398 399 /* No empty fragments. */ 400 if (frent->fe_len == 0) { 401 DPFPRINTF(("bad fragment: len 0")); 402 goto bad_fragment; 403 } 404 405 /* All fragments are 8 byte aligned. */ 406 if (frent->fe_mff && (frent->fe_len & 0x7)) { 407 DPFPRINTF(("bad fragment: mff and len %d", frent->fe_len)); 408 goto bad_fragment; 409 } 410 411 /* Respect maximum length, IP_MAXPACKET == IPV6_MAXPACKET. */ 412 if (frent->fe_off + frent->fe_len > IP_MAXPACKET) { 413 DPFPRINTF(("bad fragment: max packet %d", 414 frent->fe_off + frent->fe_len)); 415 goto bad_fragment; 416 } 417 418 DPFPRINTF((key->frc_af == AF_INET ? 419 "reass frag %d @ %d-%d" : "reass frag %#08x @ %d-%d", 420 key->frc_id, frent->fe_off, frent->fe_off + frent->fe_len)); 421 422 /* Fully buffer all of the fragments in this fragment queue. */ 423 frag = pf_find_fragment(key, &V_pf_frag_tree); 424 425 /* Create a new reassembly queue for this packet. */ 426 if (frag == NULL) { 427 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 428 if (frag == NULL) { 429 pf_flush_fragments(); 430 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 431 if (frag == NULL) { 432 REASON_SET(reason, PFRES_MEMORY); 433 goto drop_fragment; 434 } 435 } 436 437 *(struct pf_fragment_cmp *)frag = *key; 438 frag->fr_flags = 0; 439 frag->fr_timeout = time_uptime; 440 frag->fr_maxlen = frent->fe_len; 441 frag->fr_entries = 0; 442 TAILQ_INIT(&frag->fr_queue); 443 444 RB_INSERT(pf_frag_tree, &V_pf_frag_tree, frag); 445 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next); 446 447 /* We do not have a previous fragment. */ 448 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next); 449 450 return (frag); 451 } 452 453 if (frag->fr_entries >= PF_MAX_FRENT_PER_FRAGMENT) 454 goto bad_fragment; 455 456 KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue")); 457 458 /* Remember maximum fragment len for refragmentation. */ 459 if (frent->fe_len > frag->fr_maxlen) 460 frag->fr_maxlen = frent->fe_len; 461 462 /* Maximum data we have seen already. */ 463 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 464 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 465 466 /* Non terminal fragments must have more fragments flag. */ 467 if (frent->fe_off + frent->fe_len < total && !frent->fe_mff) 468 goto bad_fragment; 469 470 /* Check if we saw the last fragment already. */ 471 if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) { 472 if (frent->fe_off + frent->fe_len > total || 473 (frent->fe_off + frent->fe_len == total && frent->fe_mff)) 474 goto bad_fragment; 475 } else { 476 if (frent->fe_off + frent->fe_len == total && !frent->fe_mff) 477 goto bad_fragment; 478 } 479 480 /* Find a fragment after the current one. */ 481 prev = NULL; 482 TAILQ_FOREACH(after, &frag->fr_queue, fr_next) { 483 if (after->fe_off > frent->fe_off) 484 break; 485 prev = after; 486 } 487 488 KASSERT(prev != NULL || after != NULL, 489 ("prev != NULL || after != NULL")); 490 491 if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) { 492 uint16_t precut; 493 494 precut = prev->fe_off + prev->fe_len - frent->fe_off; 495 if (precut >= frent->fe_len) 496 goto bad_fragment; 497 DPFPRINTF(("overlap -%d", precut)); 498 m_adj(frent->fe_m, precut); 499 frent->fe_off += precut; 500 frent->fe_len -= precut; 501 } 502 503 for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off; 504 after = next) { 505 uint16_t aftercut; 506 507 aftercut = frent->fe_off + frent->fe_len - after->fe_off; 508 DPFPRINTF(("adjust overlap %d", aftercut)); 509 if (aftercut < after->fe_len) { 510 m_adj(after->fe_m, aftercut); 511 after->fe_off += aftercut; 512 after->fe_len -= aftercut; 513 break; 514 } 515 516 /* This fragment is completely overlapped, lose it. */ 517 next = TAILQ_NEXT(after, fr_next); 518 m_freem(after->fe_m); 519 TAILQ_REMOVE(&frag->fr_queue, after, fr_next); 520 uma_zfree(V_pf_frent_z, after); 521 } 522 523 if (prev == NULL) 524 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next); 525 else 526 TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next); 527 528 frag->fr_entries++; 529 530 return (frag); 531 532bad_fragment: 533 REASON_SET(reason, PFRES_FRAG); 534drop_fragment: 535 uma_zfree(V_pf_frent_z, frent); 536 return (NULL); 537} 538 539static int 540pf_isfull_fragment(struct pf_fragment *frag) 541{ 542 struct pf_frent *frent, *next; 543 uint16_t off, total; 544 545 /* Check if we are completely reassembled */ 546 if (TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) 547 return (0); 548 549 /* Maximum data we have seen already */ 550 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 551 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 552 553 /* Check if we have all the data */ 554 off = 0; 555 for (frent = TAILQ_FIRST(&frag->fr_queue); frent; frent = next) { 556 next = TAILQ_NEXT(frent, fr_next); 557 558 off += frent->fe_len; 559 if (off < total && (next == NULL || next->fe_off != off)) { 560 DPFPRINTF(("missing fragment at %d, next %d, total %d", 561 off, next == NULL ? -1 : next->fe_off, total)); 562 return (0); 563 } 564 } 565 DPFPRINTF(("%d < %d?", off, total)); 566 if (off < total) 567 return (0); 568 KASSERT(off == total, ("off == total")); 569 570 return (1); 571} 572 573static struct mbuf * 574pf_join_fragment(struct pf_fragment *frag) 575{ 576 struct mbuf *m, *m2; 577 struct pf_frent *frent, *next; 578 579 frent = TAILQ_FIRST(&frag->fr_queue); 580 next = TAILQ_NEXT(frent, fr_next); 581 582 m = frent->fe_m; 583 m_adj(m, (frent->fe_hdrlen + frent->fe_len) - m->m_pkthdr.len); 584 uma_zfree(V_pf_frent_z, frent); 585 for (frent = next; frent != NULL; frent = next) { 586 next = TAILQ_NEXT(frent, fr_next); 587 588 m2 = frent->fe_m; 589 /* Strip off ip header. */ 590 m_adj(m2, frent->fe_hdrlen); 591 /* Strip off any trailing bytes. */ 592 m_adj(m2, frent->fe_len - m2->m_pkthdr.len); 593 594 uma_zfree(V_pf_frent_z, frent); 595 m_cat(m, m2); 596 } 597 598 /* Remove from fragment queue. */ 599 pf_remove_fragment(frag); 600 601 return (m); 602} 603 604#ifdef INET 605static int 606pf_reassemble(struct mbuf **m0, struct ip *ip, int dir, u_short *reason) 607{ 608 struct mbuf *m = *m0; 609 struct pf_frent *frent; 610 struct pf_fragment *frag; 611 struct pf_fragment_cmp key; 612 uint16_t total, hdrlen; 613 614 /* Get an entry for the fragment queue */ 615 if ((frent = pf_create_fragment(reason)) == NULL) 616 return (PF_DROP); 617 618 frent->fe_m = m; 619 frent->fe_hdrlen = ip->ip_hl << 2; 620 frent->fe_extoff = 0; 621 frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2); 622 frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3; 623 frent->fe_mff = ntohs(ip->ip_off) & IP_MF; 624 625 pf_ip2key(ip, dir, &key); 626 627 if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) 628 return (PF_DROP); 629 630 /* The mbuf is part of the fragment entry, no direct free or access */ 631 m = *m0 = NULL; 632 633 if (!pf_isfull_fragment(frag)) 634 return (PF_PASS); /* drop because *m0 is NULL, no error */ 635 636 /* We have all the data */ 637 frent = TAILQ_FIRST(&frag->fr_queue); 638 KASSERT(frent != NULL, ("frent != NULL")); 639 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 640 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 641 hdrlen = frent->fe_hdrlen; 642 643 m = *m0 = pf_join_fragment(frag); 644 frag = NULL; 645 646 if (m->m_flags & M_PKTHDR) { 647 int plen = 0; 648 for (m = *m0; m; m = m->m_next) 649 plen += m->m_len; 650 m = *m0; 651 m->m_pkthdr.len = plen; 652 } 653 654 ip = mtod(m, struct ip *); 655 ip->ip_len = htons(hdrlen + total); 656 ip->ip_off &= ~(IP_MF|IP_OFFMASK); 657 658 if (hdrlen + total > IP_MAXPACKET) { 659 DPFPRINTF(("drop: too big: %d", total)); 660 ip->ip_len = 0; 661 REASON_SET(reason, PFRES_SHORT); 662 /* PF_DROP requires a valid mbuf *m0 in pf_test() */ 663 return (PF_DROP); 664 } 665 666 DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len))); 667 return (PF_PASS); 668} 669#endif /* INET */ 670 671#ifdef INET6 672static int 673pf_reassemble6(struct mbuf **m0, struct ip6_hdr *ip6, struct ip6_frag *fraghdr, 674 uint16_t hdrlen, uint16_t extoff, u_short *reason) 675{ 676 struct mbuf *m = *m0; 677 struct pf_frent *frent; 678 struct pf_fragment *frag; 679 struct pf_fragment_cmp key; 680 struct m_tag *mtag; 681 struct pf_fragment_tag *ftag; 682 int off; 683 uint32_t frag_id; 684 uint16_t total, maxlen; 685 uint8_t proto; 686 687 PF_FRAG_LOCK(); 688 689 /* Get an entry for the fragment queue. */ 690 if ((frent = pf_create_fragment(reason)) == NULL) { 691 PF_FRAG_UNLOCK(); 692 return (PF_DROP); 693 } 694 695 frent->fe_m = m; 696 frent->fe_hdrlen = hdrlen; 697 frent->fe_extoff = extoff; 698 frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen; 699 frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK); 700 frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG; 701 702 key.frc_src.v6 = ip6->ip6_src; 703 key.frc_dst.v6 = ip6->ip6_dst; 704 key.frc_af = AF_INET6; 705 /* Only the first fragment's protocol is relevant. */ 706 key.frc_proto = 0; 707 key.frc_id = fraghdr->ip6f_ident; 708 709 if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) { 710 PF_FRAG_UNLOCK(); 711 return (PF_DROP); 712 } 713 714 /* The mbuf is part of the fragment entry, no direct free or access. */ 715 m = *m0 = NULL; 716 717 if (!pf_isfull_fragment(frag)) { 718 PF_FRAG_UNLOCK(); 719 return (PF_PASS); /* Drop because *m0 is NULL, no error. */ 720 } 721 722 /* We have all the data. */ 723 extoff = frent->fe_extoff; 724 maxlen = frag->fr_maxlen; 725 frag_id = frag->fr_id; 726 frent = TAILQ_FIRST(&frag->fr_queue); 727 KASSERT(frent != NULL, ("frent != NULL")); 728 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 729 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 730 hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag); 731 732 m = *m0 = pf_join_fragment(frag); 733 frag = NULL; 734 735 PF_FRAG_UNLOCK(); 736 737 /* Take protocol from first fragment header. */ 738 m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off); 739 KASSERT(m, ("%s: short mbuf chain", __func__)); 740 proto = *(mtod(m, caddr_t) + off); 741 m = *m0; 742 743 /* Delete frag6 header */ 744 if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0) 745 goto fail; 746 747 if (m->m_flags & M_PKTHDR) { 748 int plen = 0; 749 for (m = *m0; m; m = m->m_next) 750 plen += m->m_len; 751 m = *m0; 752 m->m_pkthdr.len = plen; 753 } 754 755 if ((mtag = m_tag_get(PF_REASSEMBLED, sizeof(struct pf_fragment_tag), 756 M_NOWAIT)) == NULL) 757 goto fail; 758 ftag = (struct pf_fragment_tag *)(mtag + 1); 759 ftag->ft_hdrlen = hdrlen; 760 ftag->ft_extoff = extoff; 761 ftag->ft_maxlen = maxlen; 762 ftag->ft_id = frag_id; 763 m_tag_prepend(m, mtag); 764 765 ip6 = mtod(m, struct ip6_hdr *); 766 ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total); 767 if (extoff) { 768 /* Write protocol into next field of last extension header. */ 769 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt), 770 &off); 771 KASSERT(m, ("%s: short mbuf chain", __func__)); 772 *(mtod(m, char *) + off) = proto; 773 m = *m0; 774 } else 775 ip6->ip6_nxt = proto; 776 777 if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) { 778 DPFPRINTF(("drop: too big: %d", total)); 779 ip6->ip6_plen = 0; 780 REASON_SET(reason, PFRES_SHORT); 781 /* PF_DROP requires a valid mbuf *m0 in pf_test6(). */ 782 return (PF_DROP); 783 } 784 785 DPFPRINTF(("complete: %p(%d)", m, ntohs(ip6->ip6_plen))); 786 return (PF_PASS); 787 788fail: 789 REASON_SET(reason, PFRES_MEMORY); 790 /* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */ 791 return (PF_DROP); 792} 793#endif /* INET6 */ 794 795#ifdef INET 796static struct mbuf * 797pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff, 798 int drop, int *nomem) 799{ 800 struct mbuf *m = *m0; 801 struct pf_frent *frp, *fra, *cur = NULL; 802 int ip_len = ntohs(h->ip_len) - (h->ip_hl << 2); 803 u_int16_t off = ntohs(h->ip_off) << 3; 804 u_int16_t max = ip_len + off; 805 int hosed = 0; 806 807 PF_FRAG_ASSERT(); 808 KASSERT((*frag == NULL || !BUFFER_FRAGMENTS(*frag)), 809 ("!(*frag == NULL || !BUFFER_FRAGMENTS(*frag)): %s", __FUNCTION__)); 810 811 /* Create a new range queue for this packet */ 812 if (*frag == NULL) { 813 *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 814 if (*frag == NULL) { 815 pf_flush_fragments(); 816 *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 817 if (*frag == NULL) 818 goto no_mem; 819 } 820 821 /* Get an entry for the queue */ 822 cur = uma_zalloc(V_pf_frent_z, M_NOWAIT); 823 if (cur == NULL) { 824 uma_zfree(V_pf_frag_z, *frag); 825 *frag = NULL; 826 goto no_mem; 827 } 828 829 (*frag)->fr_flags = PFFRAG_NOBUFFER; 830 (*frag)->fr_max = 0; 831 (*frag)->fr_src.v4 = h->ip_src; 832 (*frag)->fr_dst.v4 = h->ip_dst; 833 (*frag)->fr_af = AF_INET; 834 (*frag)->fr_proto = h->ip_p; 835 (*frag)->fr_id = h->ip_id; 836 (*frag)->fr_timeout = time_uptime; 837 838 cur->fe_off = off; 839 cur->fe_len = max; /* TODO: fe_len = max - off ? */ 840 TAILQ_INIT(&(*frag)->fr_queue); 841 TAILQ_INSERT_HEAD(&(*frag)->fr_queue, cur, fr_next); 842 843 RB_INSERT(pf_frag_tree, &V_pf_cache_tree, *frag); 844 TAILQ_INSERT_HEAD(&V_pf_cachequeue, *frag, frag_next); 845 846 DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max)); 847 848 goto pass; 849 } 850 851 /* 852 * Find a fragment after the current one: 853 * - off contains the real shifted offset. 854 */ 855 frp = NULL; 856 TAILQ_FOREACH(fra, &(*frag)->fr_queue, fr_next) { 857 if (fra->fe_off > off) 858 break; 859 frp = fra; 860 } 861 862 KASSERT((frp != NULL || fra != NULL), 863 ("!(frp != NULL || fra != NULL): %s", __FUNCTION__)); 864 865 if (frp != NULL) { 866 int precut; 867 868 precut = frp->fe_len - off; 869 if (precut >= ip_len) { 870 /* Fragment is entirely a duplicate */ 871 DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n", 872 h->ip_id, frp->fe_off, frp->fe_len, off, max)); 873 goto drop_fragment; 874 } 875 if (precut == 0) { 876 /* They are adjacent. Fixup cache entry */ 877 DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n", 878 h->ip_id, frp->fe_off, frp->fe_len, off, max)); 879 frp->fe_len = max; 880 } else if (precut > 0) { 881 /* The first part of this payload overlaps with a 882 * fragment that has already been passed. 883 * Need to trim off the first part of the payload. 884 * But to do so easily, we need to create another 885 * mbuf to throw the original header into. 886 */ 887 888 DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n", 889 h->ip_id, precut, frp->fe_off, frp->fe_len, off, 890 max)); 891 892 off += precut; 893 max -= precut; 894 /* Update the previous frag to encompass this one */ 895 frp->fe_len = max; 896 897 if (!drop) { 898 /* XXX Optimization opportunity 899 * This is a very heavy way to trim the payload. 900 * we could do it much faster by diddling mbuf 901 * internals but that would be even less legible 902 * than this mbuf magic. For my next trick, 903 * I'll pull a rabbit out of my laptop. 904 */ 905 *m0 = m_dup(m, M_NOWAIT); 906 if (*m0 == NULL) 907 goto no_mem; 908 /* From KAME Project : We have missed this! */ 909 m_adj(*m0, (h->ip_hl << 2) - 910 (*m0)->m_pkthdr.len); 911 912 KASSERT(((*m0)->m_next == NULL), 913 ("(*m0)->m_next != NULL: %s", 914 __FUNCTION__)); 915 m_adj(m, precut + (h->ip_hl << 2)); 916 m_cat(*m0, m); 917 m = *m0; 918 if (m->m_flags & M_PKTHDR) { 919 int plen = 0; 920 struct mbuf *t; 921 for (t = m; t; t = t->m_next) 922 plen += t->m_len; 923 m->m_pkthdr.len = plen; 924 } 925 926 927 h = mtod(m, struct ip *); 928 929 KASSERT(((int)m->m_len == 930 ntohs(h->ip_len) - precut), 931 ("m->m_len != ntohs(h->ip_len) - precut: %s", 932 __FUNCTION__)); 933 h->ip_off = htons(ntohs(h->ip_off) + 934 (precut >> 3)); 935 h->ip_len = htons(ntohs(h->ip_len) - precut); 936 } else { 937 hosed++; 938 } 939 } else { 940 /* There is a gap between fragments */ 941 942 DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n", 943 h->ip_id, -precut, frp->fe_off, frp->fe_len, off, 944 max)); 945 946 cur = uma_zalloc(V_pf_frent_z, M_NOWAIT); 947 if (cur == NULL) 948 goto no_mem; 949 950 cur->fe_off = off; 951 cur->fe_len = max; 952 TAILQ_INSERT_AFTER(&(*frag)->fr_queue, frp, cur, fr_next); 953 } 954 } 955 956 if (fra != NULL) { 957 int aftercut; 958 int merge = 0; 959 960 aftercut = max - fra->fe_off; 961 if (aftercut == 0) { 962 /* Adjacent fragments */ 963 DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n", 964 h->ip_id, off, max, fra->fe_off, fra->fe_len)); 965 fra->fe_off = off; 966 merge = 1; 967 } else if (aftercut > 0) { 968 /* Need to chop off the tail of this fragment */ 969 DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n", 970 h->ip_id, aftercut, off, max, fra->fe_off, 971 fra->fe_len)); 972 fra->fe_off = off; 973 max -= aftercut; 974 975 merge = 1; 976 977 if (!drop) { 978 m_adj(m, -aftercut); 979 if (m->m_flags & M_PKTHDR) { 980 int plen = 0; 981 struct mbuf *t; 982 for (t = m; t; t = t->m_next) 983 plen += t->m_len; 984 m->m_pkthdr.len = plen; 985 } 986 h = mtod(m, struct ip *); 987 KASSERT(((int)m->m_len == ntohs(h->ip_len) - aftercut), 988 ("m->m_len != ntohs(h->ip_len) - aftercut: %s", 989 __FUNCTION__)); 990 h->ip_len = htons(ntohs(h->ip_len) - aftercut); 991 } else { 992 hosed++; 993 } 994 } else if (frp == NULL) { 995 /* There is a gap between fragments */ 996 DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n", 997 h->ip_id, -aftercut, off, max, fra->fe_off, 998 fra->fe_len)); 999 1000 cur = uma_zalloc(V_pf_frent_z, M_NOWAIT); 1001 if (cur == NULL) 1002 goto no_mem; 1003 1004 cur->fe_off = off; 1005 cur->fe_len = max; 1006 TAILQ_INSERT_HEAD(&(*frag)->fr_queue, cur, fr_next); 1007 } 1008 1009 1010 /* Need to glue together two separate fragment descriptors */ 1011 if (merge) { 1012 if (cur && fra->fe_off <= cur->fe_len) { 1013 /* Need to merge in a previous 'cur' */ 1014 DPFPRINTF(("fragcache[%d]: adjacent(merge " 1015 "%d-%d) %d-%d (%d-%d)\n", 1016 h->ip_id, cur->fe_off, cur->fe_len, off, 1017 max, fra->fe_off, fra->fe_len)); 1018 fra->fe_off = cur->fe_off; 1019 TAILQ_REMOVE(&(*frag)->fr_queue, cur, fr_next); 1020 uma_zfree(V_pf_frent_z, cur); 1021 cur = NULL; 1022 1023 } else if (frp && fra->fe_off <= frp->fe_len) { 1024 /* Need to merge in a modified 'frp' */ 1025 KASSERT((cur == NULL), ("cur != NULL: %s", 1026 __FUNCTION__)); 1027 DPFPRINTF(("fragcache[%d]: adjacent(merge " 1028 "%d-%d) %d-%d (%d-%d)\n", 1029 h->ip_id, frp->fe_off, frp->fe_len, off, 1030 max, fra->fe_off, fra->fe_len)); 1031 fra->fe_off = frp->fe_off; 1032 TAILQ_REMOVE(&(*frag)->fr_queue, frp, fr_next); 1033 uma_zfree(V_pf_frent_z, frp); 1034 frp = NULL; 1035 1036 } 1037 } 1038 } 1039 1040 if (hosed) { 1041 /* 1042 * We must keep tracking the overall fragment even when 1043 * we're going to drop it anyway so that we know when to 1044 * free the overall descriptor. Thus we drop the frag late. 1045 */ 1046 goto drop_fragment; 1047 } 1048 1049 1050 pass: 1051 /* Update maximum data size */ 1052 if ((*frag)->fr_max < max) 1053 (*frag)->fr_max = max; 1054 1055 /* This is the last segment */ 1056 if (!mff) 1057 (*frag)->fr_flags |= PFFRAG_SEENLAST; 1058 1059 /* Check if we are completely reassembled */ 1060 if (((*frag)->fr_flags & PFFRAG_SEENLAST) && 1061 TAILQ_FIRST(&(*frag)->fr_queue)->fe_off == 0 && 1062 TAILQ_FIRST(&(*frag)->fr_queue)->fe_len == (*frag)->fr_max) { 1063 /* Remove from fragment queue */ 1064 DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id, 1065 (*frag)->fr_max)); 1066 pf_free_fragment(*frag); 1067 *frag = NULL; 1068 } 1069 1070 return (m); 1071 1072 no_mem: 1073 *nomem = 1; 1074 1075 /* Still need to pay attention to !IP_MF */ 1076 if (!mff && *frag != NULL) 1077 (*frag)->fr_flags |= PFFRAG_SEENLAST; 1078 1079 m_freem(m); 1080 return (NULL); 1081 1082 drop_fragment: 1083 1084 /* Still need to pay attention to !IP_MF */ 1085 if (!mff && *frag != NULL) 1086 (*frag)->fr_flags |= PFFRAG_SEENLAST; 1087 1088 if (drop) { 1089 /* This fragment has been deemed bad. Don't reass */ 1090 if (((*frag)->fr_flags & PFFRAG_DROP) == 0) 1091 DPFPRINTF(("fragcache[%d]: dropping overall fragment\n", 1092 h->ip_id)); 1093 (*frag)->fr_flags |= PFFRAG_DROP; 1094 } 1095 1096 m_freem(m); 1097 return (NULL); 1098} 1099#endif /* INET */ 1100 1101#ifdef INET6 1102int 1103pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag) 1104{ 1105 struct mbuf *m = *m0, *t; 1106 struct pf_fragment_tag *ftag = (struct pf_fragment_tag *)(mtag + 1); 1107 struct pf_pdesc pd; 1108 uint32_t frag_id; 1109 uint16_t hdrlen, extoff, maxlen; 1110 uint8_t proto; 1111 int error, action; 1112 1113 hdrlen = ftag->ft_hdrlen; 1114 extoff = ftag->ft_extoff; 1115 maxlen = ftag->ft_maxlen; 1116 frag_id = ftag->ft_id; 1117 m_tag_delete(m, mtag); 1118 mtag = NULL; 1119 ftag = NULL; 1120 1121 if (extoff) { 1122 int off; 1123 1124 /* Use protocol from next field of last extension header */ 1125 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt), 1126 &off); 1127 KASSERT((m != NULL), ("pf_refragment6: short mbuf chain")); 1128 proto = *(mtod(m, caddr_t) + off); 1129 *(mtod(m, char *) + off) = IPPROTO_FRAGMENT; 1130 m = *m0; 1131 } else { 1132 struct ip6_hdr *hdr; 1133 1134 hdr = mtod(m, struct ip6_hdr *); 1135 proto = hdr->ip6_nxt; 1136 hdr->ip6_nxt = IPPROTO_FRAGMENT; 1137 } 1138 1139 /* The MTU must be a multiple of 8 bytes, or we risk doing the 1140 * fragmentation wrong. */ 1141 maxlen = maxlen & ~7; 1142 1143 /* 1144 * Maxlen may be less than 8 if there was only a single 1145 * fragment. As it was fragmented before, add a fragment 1146 * header also for a single fragment. If total or maxlen 1147 * is less than 8, ip6_fragment() will return EMSGSIZE and 1148 * we drop the packet. 1149 */ 1150 error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id); 1151 m = (*m0)->m_nextpkt; 1152 (*m0)->m_nextpkt = NULL; 1153 if (error == 0) { 1154 /* The first mbuf contains the unfragmented packet. */ 1155 m_freem(*m0); 1156 *m0 = NULL; 1157 action = PF_PASS; 1158 } else { 1159 /* Drop expects an mbuf to free. */ 1160 DPFPRINTF(("refragment error %d", error)); 1161 action = PF_DROP; 1162 } 1163 for (t = m; m; m = t) { 1164 t = m->m_nextpkt; 1165 m->m_nextpkt = NULL; 1166 m->m_flags |= M_SKIP_FIREWALL; 1167 memset(&pd, 0, sizeof(pd)); 1168 pd.pf_mtag = pf_find_mtag(m); 1169 if (error == 0) 1170 ip6_forward(m, 0); 1171 else 1172 m_freem(m); 1173 } 1174 1175 return (action); 1176} 1177#endif /* INET6 */ 1178 1179#ifdef INET 1180int 1181pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason, 1182 struct pf_pdesc *pd) 1183{ 1184 struct mbuf *m = *m0; 1185 struct pf_rule *r; 1186 struct pf_fragment *frag = NULL; 1187 struct pf_fragment_cmp key; 1188 struct ip *h = mtod(m, struct ip *); 1189 int mff = (ntohs(h->ip_off) & IP_MF); 1190 int hlen = h->ip_hl << 2; 1191 u_int16_t fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3; 1192 u_int16_t max; 1193 int ip_len; 1194 int ip_off; 1195 int tag = -1; 1196 int verdict; 1197 1198 PF_RULES_RASSERT(); 1199 1200 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1201 while (r != NULL) { 1202 r->evaluations++; 1203 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1204 r = r->skip[PF_SKIP_IFP].ptr; 1205 else if (r->direction && r->direction != dir) 1206 r = r->skip[PF_SKIP_DIR].ptr; 1207 else if (r->af && r->af != AF_INET) 1208 r = r->skip[PF_SKIP_AF].ptr; 1209 else if (r->proto && r->proto != h->ip_p) 1210 r = r->skip[PF_SKIP_PROTO].ptr; 1211 else if (PF_MISMATCHAW(&r->src.addr, 1212 (struct pf_addr *)&h->ip_src.s_addr, AF_INET, 1213 r->src.neg, kif, M_GETFIB(m))) 1214 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1215 else if (PF_MISMATCHAW(&r->dst.addr, 1216 (struct pf_addr *)&h->ip_dst.s_addr, AF_INET, 1217 r->dst.neg, NULL, M_GETFIB(m))) 1218 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1219 else if (r->match_tag && !pf_match_tag(m, r, &tag, 1220 pd->pf_mtag ? pd->pf_mtag->tag : 0)) 1221 r = TAILQ_NEXT(r, entries); 1222 else 1223 break; 1224 } 1225 1226 if (r == NULL || r->action == PF_NOSCRUB) 1227 return (PF_PASS); 1228 else { 1229 r->packets[dir == PF_OUT]++; 1230 r->bytes[dir == PF_OUT] += pd->tot_len; 1231 } 1232 1233 /* Check for illegal packets */ 1234 if (hlen < (int)sizeof(struct ip)) 1235 goto drop; 1236 1237 if (hlen > ntohs(h->ip_len)) 1238 goto drop; 1239 1240 /* Clear IP_DF if the rule uses the no-df option */ 1241 if (r->rule_flag & PFRULE_NODF && h->ip_off & htons(IP_DF)) { 1242 u_int16_t ip_off = h->ip_off; 1243 1244 h->ip_off &= htons(~IP_DF); 1245 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1246 } 1247 1248 /* We will need other tests here */ 1249 if (!fragoff && !mff) 1250 goto no_fragment; 1251 1252 /* We're dealing with a fragment now. Don't allow fragments 1253 * with IP_DF to enter the cache. If the flag was cleared by 1254 * no-df above, fine. Otherwise drop it. 1255 */ 1256 if (h->ip_off & htons(IP_DF)) { 1257 DPFPRINTF(("IP_DF\n")); 1258 goto bad; 1259 } 1260 1261 ip_len = ntohs(h->ip_len) - hlen; 1262 ip_off = (ntohs(h->ip_off) & IP_OFFMASK) << 3; 1263 1264 /* All fragments are 8 byte aligned */ 1265 if (mff && (ip_len & 0x7)) { 1266 DPFPRINTF(("mff and %d\n", ip_len)); 1267 goto bad; 1268 } 1269 1270 /* Respect maximum length */ 1271 if (fragoff + ip_len > IP_MAXPACKET) { 1272 DPFPRINTF(("max packet %d\n", fragoff + ip_len)); 1273 goto bad; 1274 } 1275 max = fragoff + ip_len; 1276 1277 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) { 1278 1279 /* Fully buffer all of the fragments */ 1280 PF_FRAG_LOCK(); 1281 1282 pf_ip2key(h, dir, &key); 1283 frag = pf_find_fragment(&key, &V_pf_frag_tree); 1284 1285 /* Check if we saw the last fragment already */ 1286 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 1287 max > frag->fr_max) 1288 goto bad; 1289 1290 /* Might return a completely reassembled mbuf, or NULL */ 1291 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max)); 1292 verdict = pf_reassemble(m0, h, dir, reason); 1293 PF_FRAG_UNLOCK(); 1294 1295 if (verdict != PF_PASS) 1296 return (PF_DROP); 1297 1298 m = *m0; 1299 if (m == NULL) 1300 return (PF_DROP); 1301 1302 /* use mtag from concatenated mbuf chain */ 1303 pd->pf_mtag = pf_find_mtag(m); 1304#ifdef DIAGNOSTIC 1305 if (pd->pf_mtag == NULL) { 1306 printf("%s: pf_find_mtag returned NULL(1)\n", __func__); 1307 if ((pd->pf_mtag = pf_get_mtag(m)) == NULL) { 1308 m_freem(m); 1309 *m0 = NULL; 1310 goto no_mem; 1311 } 1312 } 1313#endif 1314 h = mtod(m, struct ip *); 1315 } else { 1316 /* non-buffering fragment cache (drops or masks overlaps) */ 1317 int nomem = 0; 1318 1319 if (dir == PF_OUT && pd->pf_mtag->flags & PF_TAG_FRAGCACHE) { 1320 /* 1321 * Already passed the fragment cache in the 1322 * input direction. If we continued, it would 1323 * appear to be a dup and would be dropped. 1324 */ 1325 goto fragment_pass; 1326 } 1327 1328 PF_FRAG_LOCK(); 1329 pf_ip2key(h, dir, &key); 1330 frag = pf_find_fragment(&key, &V_pf_cache_tree); 1331 1332 /* Check if we saw the last fragment already */ 1333 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 1334 max > frag->fr_max) { 1335 if (r->rule_flag & PFRULE_FRAGDROP) 1336 frag->fr_flags |= PFFRAG_DROP; 1337 goto bad; 1338 } 1339 1340 *m0 = m = pf_fragcache(m0, h, &frag, mff, 1341 (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem); 1342 PF_FRAG_UNLOCK(); 1343 if (m == NULL) { 1344 if (nomem) 1345 goto no_mem; 1346 goto drop; 1347 } 1348 1349 /* use mtag from copied and trimmed mbuf chain */ 1350 pd->pf_mtag = pf_find_mtag(m); 1351#ifdef DIAGNOSTIC 1352 if (pd->pf_mtag == NULL) { 1353 printf("%s: pf_find_mtag returned NULL(2)\n", __func__); 1354 if ((pd->pf_mtag = pf_get_mtag(m)) == NULL) { 1355 m_freem(m); 1356 *m0 = NULL; 1357 goto no_mem; 1358 } 1359 } 1360#endif 1361 if (dir == PF_IN) 1362 pd->pf_mtag->flags |= PF_TAG_FRAGCACHE; 1363 1364 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP)) 1365 goto drop; 1366 goto fragment_pass; 1367 } 1368 1369 no_fragment: 1370 /* At this point, only IP_DF is allowed in ip_off */ 1371 if (h->ip_off & ~htons(IP_DF)) { 1372 u_int16_t ip_off = h->ip_off; 1373 1374 h->ip_off &= htons(IP_DF); 1375 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1376 } 1377 1378 /* not missing a return here */ 1379 1380 fragment_pass: 1381 pf_scrub_ip(&m, r->rule_flag, r->min_ttl, r->set_tos); 1382 1383 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) 1384 pd->flags |= PFDESC_IP_REAS; 1385 return (PF_PASS); 1386 1387 no_mem: 1388 REASON_SET(reason, PFRES_MEMORY); 1389 if (r != NULL && r->log) 1390 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd, 1391 1); 1392 return (PF_DROP); 1393 1394 drop: 1395 REASON_SET(reason, PFRES_NORM); 1396 if (r != NULL && r->log) 1397 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd, 1398 1); 1399 return (PF_DROP); 1400 1401 bad: 1402 DPFPRINTF(("dropping bad fragment\n")); 1403 1404 /* Free associated fragments */ 1405 if (frag != NULL) { 1406 pf_free_fragment(frag); 1407 PF_FRAG_UNLOCK(); 1408 } 1409 1410 REASON_SET(reason, PFRES_FRAG); 1411 if (r != NULL && r->log) 1412 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd, 1413 1); 1414 1415 return (PF_DROP); 1416} 1417#endif 1418 1419#ifdef INET6 1420int 1421pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif, 1422 u_short *reason, struct pf_pdesc *pd) 1423{ 1424 struct mbuf *m = *m0; 1425 struct pf_rule *r; 1426 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1427 int extoff; 1428 int off; 1429 struct ip6_ext ext; 1430 struct ip6_opt opt; 1431 struct ip6_opt_jumbo jumbo; 1432 struct ip6_frag frag; 1433 u_int32_t jumbolen = 0, plen; 1434 int optend; 1435 int ooff; 1436 u_int8_t proto; 1437 int terminal; 1438 1439 PF_RULES_RASSERT(); 1440 1441 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1442 while (r != NULL) { 1443 r->evaluations++; 1444 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1445 r = r->skip[PF_SKIP_IFP].ptr; 1446 else if (r->direction && r->direction != dir) 1447 r = r->skip[PF_SKIP_DIR].ptr; 1448 else if (r->af && r->af != AF_INET6) 1449 r = r->skip[PF_SKIP_AF].ptr; 1450#if 0 /* header chain! */ 1451 else if (r->proto && r->proto != h->ip6_nxt) 1452 r = r->skip[PF_SKIP_PROTO].ptr; 1453#endif 1454 else if (PF_MISMATCHAW(&r->src.addr, 1455 (struct pf_addr *)&h->ip6_src, AF_INET6, 1456 r->src.neg, kif, M_GETFIB(m))) 1457 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1458 else if (PF_MISMATCHAW(&r->dst.addr, 1459 (struct pf_addr *)&h->ip6_dst, AF_INET6, 1460 r->dst.neg, NULL, M_GETFIB(m))) 1461 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1462 else 1463 break; 1464 } 1465 1466 if (r == NULL || r->action == PF_NOSCRUB) 1467 return (PF_PASS); 1468 else { 1469 r->packets[dir == PF_OUT]++; 1470 r->bytes[dir == PF_OUT] += pd->tot_len; 1471 } 1472 1473 /* Check for illegal packets */ 1474 if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len) 1475 goto drop; 1476 1477 extoff = 0; 1478 off = sizeof(struct ip6_hdr); 1479 proto = h->ip6_nxt; 1480 terminal = 0; 1481 do { 1482 switch (proto) { 1483 case IPPROTO_FRAGMENT: 1484 goto fragment; 1485 break; 1486 case IPPROTO_AH: 1487 case IPPROTO_ROUTING: 1488 case IPPROTO_DSTOPTS: 1489 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1490 NULL, AF_INET6)) 1491 goto shortpkt; 1492 extoff = off; 1493 if (proto == IPPROTO_AH) 1494 off += (ext.ip6e_len + 2) * 4; 1495 else 1496 off += (ext.ip6e_len + 1) * 8; 1497 proto = ext.ip6e_nxt; 1498 break; 1499 case IPPROTO_HOPOPTS: 1500 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1501 NULL, AF_INET6)) 1502 goto shortpkt; 1503 extoff = off; 1504 optend = off + (ext.ip6e_len + 1) * 8; 1505 ooff = off + sizeof(ext); 1506 do { 1507 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type, 1508 sizeof(opt.ip6o_type), NULL, NULL, 1509 AF_INET6)) 1510 goto shortpkt; 1511 if (opt.ip6o_type == IP6OPT_PAD1) { 1512 ooff++; 1513 continue; 1514 } 1515 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt), 1516 NULL, NULL, AF_INET6)) 1517 goto shortpkt; 1518 if (ooff + sizeof(opt) + opt.ip6o_len > optend) 1519 goto drop; 1520 switch (opt.ip6o_type) { 1521 case IP6OPT_JUMBO: 1522 if (h->ip6_plen != 0) 1523 goto drop; 1524 if (!pf_pull_hdr(m, ooff, &jumbo, 1525 sizeof(jumbo), NULL, NULL, 1526 AF_INET6)) 1527 goto shortpkt; 1528 memcpy(&jumbolen, jumbo.ip6oj_jumbo_len, 1529 sizeof(jumbolen)); 1530 jumbolen = ntohl(jumbolen); 1531 if (jumbolen <= IPV6_MAXPACKET) 1532 goto drop; 1533 if (sizeof(struct ip6_hdr) + jumbolen != 1534 m->m_pkthdr.len) 1535 goto drop; 1536 break; 1537 default: 1538 break; 1539 } 1540 ooff += sizeof(opt) + opt.ip6o_len; 1541 } while (ooff < optend); 1542 1543 off = optend; 1544 proto = ext.ip6e_nxt; 1545 break; 1546 default: 1547 terminal = 1; 1548 break; 1549 } 1550 } while (!terminal); 1551 1552 /* jumbo payload option must be present, or plen > 0 */ 1553 if (ntohs(h->ip6_plen) == 0) 1554 plen = jumbolen; 1555 else 1556 plen = ntohs(h->ip6_plen); 1557 if (plen == 0) 1558 goto drop; 1559 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1560 goto shortpkt; 1561 1562 pf_scrub_ip6(&m, r->min_ttl); 1563 1564 return (PF_PASS); 1565 1566 fragment: 1567 /* Jumbo payload packets cannot be fragmented. */ 1568 plen = ntohs(h->ip6_plen); 1569 if (plen == 0 || jumbolen) 1570 goto drop; 1571 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1572 goto shortpkt; 1573 1574 if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6)) 1575 goto shortpkt; 1576 1577 /* Offset now points to data portion. */ 1578 off += sizeof(frag); 1579 1580 /* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */ 1581 if (pf_reassemble6(m0, h, &frag, off, extoff, reason) != PF_PASS) 1582 return (PF_DROP); 1583 m = *m0; 1584 if (m == NULL) 1585 return (PF_DROP); 1586 1587 pd->flags |= PFDESC_IP_REAS; 1588 return (PF_PASS); 1589 1590 shortpkt: 1591 REASON_SET(reason, PFRES_SHORT); 1592 if (r != NULL && r->log) 1593 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd, 1594 1); 1595 return (PF_DROP); 1596 1597 drop: 1598 REASON_SET(reason, PFRES_NORM); 1599 if (r != NULL && r->log) 1600 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd, 1601 1); 1602 return (PF_DROP); 1603} 1604#endif /* INET6 */ 1605 1606int 1607pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff, 1608 int off, void *h, struct pf_pdesc *pd) 1609{ 1610 struct pf_rule *r, *rm = NULL; 1611 struct tcphdr *th = pd->hdr.tcp; 1612 int rewrite = 0; 1613 u_short reason; 1614 u_int8_t flags; 1615 sa_family_t af = pd->af; 1616 1617 PF_RULES_RASSERT(); 1618 1619 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1620 while (r != NULL) { 1621 r->evaluations++; 1622 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1623 r = r->skip[PF_SKIP_IFP].ptr; 1624 else if (r->direction && r->direction != dir) 1625 r = r->skip[PF_SKIP_DIR].ptr; 1626 else if (r->af && r->af != af) 1627 r = r->skip[PF_SKIP_AF].ptr; 1628 else if (r->proto && r->proto != pd->proto) 1629 r = r->skip[PF_SKIP_PROTO].ptr; 1630 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, 1631 r->src.neg, kif, M_GETFIB(m))) 1632 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1633 else if (r->src.port_op && !pf_match_port(r->src.port_op, 1634 r->src.port[0], r->src.port[1], th->th_sport)) 1635 r = r->skip[PF_SKIP_SRC_PORT].ptr; 1636 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, 1637 r->dst.neg, NULL, M_GETFIB(m))) 1638 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1639 else if (r->dst.port_op && !pf_match_port(r->dst.port_op, 1640 r->dst.port[0], r->dst.port[1], th->th_dport)) 1641 r = r->skip[PF_SKIP_DST_PORT].ptr; 1642 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match( 1643 pf_osfp_fingerprint(pd, m, off, th), 1644 r->os_fingerprint)) 1645 r = TAILQ_NEXT(r, entries); 1646 else { 1647 rm = r; 1648 break; 1649 } 1650 } 1651 1652 if (rm == NULL || rm->action == PF_NOSCRUB) 1653 return (PF_PASS); 1654 else { 1655 r->packets[dir == PF_OUT]++; 1656 r->bytes[dir == PF_OUT] += pd->tot_len; 1657 } 1658 1659 if (rm->rule_flag & PFRULE_REASSEMBLE_TCP) 1660 pd->flags |= PFDESC_TCP_NORM; 1661 1662 flags = th->th_flags; 1663 if (flags & TH_SYN) { 1664 /* Illegal packet */ 1665 if (flags & TH_RST) 1666 goto tcp_drop; 1667 1668 if (flags & TH_FIN) 1669 goto tcp_drop; 1670 } else { 1671 /* Illegal packet */ 1672 if (!(flags & (TH_ACK|TH_RST))) 1673 goto tcp_drop; 1674 } 1675 1676 if (!(flags & TH_ACK)) { 1677 /* These flags are only valid if ACK is set */ 1678 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG)) 1679 goto tcp_drop; 1680 } 1681 1682 /* Check for illegal header length */ 1683 if (th->th_off < (sizeof(struct tcphdr) >> 2)) 1684 goto tcp_drop; 1685 1686 /* If flags changed, or reserved data set, then adjust */ 1687 if (flags != th->th_flags || th->th_x2 != 0) { 1688 u_int16_t ov, nv; 1689 1690 ov = *(u_int16_t *)(&th->th_ack + 1); 1691 th->th_flags = flags; 1692 th->th_x2 = 0; 1693 nv = *(u_int16_t *)(&th->th_ack + 1); 1694 1695 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, ov, nv, 0); 1696 rewrite = 1; 1697 } 1698 1699 /* Remove urgent pointer, if TH_URG is not set */ 1700 if (!(flags & TH_URG) && th->th_urp) { 1701 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, th->th_urp, 1702 0, 0); 1703 th->th_urp = 0; 1704 rewrite = 1; 1705 } 1706 1707 /* Process options */ 1708 if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af)) 1709 rewrite = 1; 1710 1711 /* copy back packet headers if we sanitized */ 1712 if (rewrite) 1713 m_copyback(m, off, sizeof(*th), (caddr_t)th); 1714 1715 return (PF_PASS); 1716 1717 tcp_drop: 1718 REASON_SET(&reason, PFRES_NORM); 1719 if (rm != NULL && r->log) 1720 PFLOG_PACKET(kif, m, AF_INET, dir, reason, r, NULL, NULL, pd, 1721 1); 1722 return (PF_DROP); 1723} 1724 1725int 1726pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd, 1727 struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst) 1728{ 1729 u_int32_t tsval, tsecr; 1730 u_int8_t hdr[60]; 1731 u_int8_t *opt; 1732 1733 KASSERT((src->scrub == NULL), 1734 ("pf_normalize_tcp_init: src->scrub != NULL")); 1735 1736 src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT); 1737 if (src->scrub == NULL) 1738 return (1); 1739 1740 switch (pd->af) { 1741#ifdef INET 1742 case AF_INET: { 1743 struct ip *h = mtod(m, struct ip *); 1744 src->scrub->pfss_ttl = h->ip_ttl; 1745 break; 1746 } 1747#endif /* INET */ 1748#ifdef INET6 1749 case AF_INET6: { 1750 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1751 src->scrub->pfss_ttl = h->ip6_hlim; 1752 break; 1753 } 1754#endif /* INET6 */ 1755 } 1756 1757 1758 /* 1759 * All normalizations below are only begun if we see the start of 1760 * the connections. They must all set an enabled bit in pfss_flags 1761 */ 1762 if ((th->th_flags & TH_SYN) == 0) 1763 return (0); 1764 1765 1766 if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub && 1767 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1768 /* Diddle with TCP options */ 1769 int hlen; 1770 opt = hdr + sizeof(struct tcphdr); 1771 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1772 while (hlen >= TCPOLEN_TIMESTAMP) { 1773 switch (*opt) { 1774 case TCPOPT_EOL: /* FALLTHROUGH */ 1775 case TCPOPT_NOP: 1776 opt++; 1777 hlen--; 1778 break; 1779 case TCPOPT_TIMESTAMP: 1780 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1781 src->scrub->pfss_flags |= 1782 PFSS_TIMESTAMP; 1783 src->scrub->pfss_ts_mod = 1784 htonl(arc4random()); 1785 1786 /* note PFSS_PAWS not set yet */ 1787 memcpy(&tsval, &opt[2], 1788 sizeof(u_int32_t)); 1789 memcpy(&tsecr, &opt[6], 1790 sizeof(u_int32_t)); 1791 src->scrub->pfss_tsval0 = ntohl(tsval); 1792 src->scrub->pfss_tsval = ntohl(tsval); 1793 src->scrub->pfss_tsecr = ntohl(tsecr); 1794 getmicrouptime(&src->scrub->pfss_last); 1795 } 1796 /* FALLTHROUGH */ 1797 default: 1798 hlen -= MAX(opt[1], 2); 1799 opt += MAX(opt[1], 2); 1800 break; 1801 } 1802 } 1803 } 1804 1805 return (0); 1806} 1807 1808void 1809pf_normalize_tcp_cleanup(struct pf_state *state) 1810{ 1811 if (state->src.scrub) 1812 uma_zfree(V_pf_state_scrub_z, state->src.scrub); 1813 if (state->dst.scrub) 1814 uma_zfree(V_pf_state_scrub_z, state->dst.scrub); 1815 1816 /* Someday... flush the TCP segment reassembly descriptors. */ 1817} 1818 1819int 1820pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd, 1821 u_short *reason, struct tcphdr *th, struct pf_state *state, 1822 struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback) 1823{ 1824 struct timeval uptime; 1825 u_int32_t tsval, tsecr; 1826 u_int tsval_from_last; 1827 u_int8_t hdr[60]; 1828 u_int8_t *opt; 1829 int copyback = 0; 1830 int got_ts = 0; 1831 1832 KASSERT((src->scrub || dst->scrub), 1833 ("%s: src->scrub && dst->scrub!", __func__)); 1834 1835 /* 1836 * Enforce the minimum TTL seen for this connection. Negate a common 1837 * technique to evade an intrusion detection system and confuse 1838 * firewall state code. 1839 */ 1840 switch (pd->af) { 1841#ifdef INET 1842 case AF_INET: { 1843 if (src->scrub) { 1844 struct ip *h = mtod(m, struct ip *); 1845 if (h->ip_ttl > src->scrub->pfss_ttl) 1846 src->scrub->pfss_ttl = h->ip_ttl; 1847 h->ip_ttl = src->scrub->pfss_ttl; 1848 } 1849 break; 1850 } 1851#endif /* INET */ 1852#ifdef INET6 1853 case AF_INET6: { 1854 if (src->scrub) { 1855 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1856 if (h->ip6_hlim > src->scrub->pfss_ttl) 1857 src->scrub->pfss_ttl = h->ip6_hlim; 1858 h->ip6_hlim = src->scrub->pfss_ttl; 1859 } 1860 break; 1861 } 1862#endif /* INET6 */ 1863 } 1864 1865 if (th->th_off > (sizeof(struct tcphdr) >> 2) && 1866 ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) || 1867 (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) && 1868 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1869 /* Diddle with TCP options */ 1870 int hlen; 1871 opt = hdr + sizeof(struct tcphdr); 1872 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1873 while (hlen >= TCPOLEN_TIMESTAMP) { 1874 switch (*opt) { 1875 case TCPOPT_EOL: /* FALLTHROUGH */ 1876 case TCPOPT_NOP: 1877 opt++; 1878 hlen--; 1879 break; 1880 case TCPOPT_TIMESTAMP: 1881 /* Modulate the timestamps. Can be used for 1882 * NAT detection, OS uptime determination or 1883 * reboot detection. 1884 */ 1885 1886 if (got_ts) { 1887 /* Huh? Multiple timestamps!? */ 1888 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1889 DPFPRINTF(("multiple TS??")); 1890 pf_print_state(state); 1891 printf("\n"); 1892 } 1893 REASON_SET(reason, PFRES_TS); 1894 return (PF_DROP); 1895 } 1896 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1897 memcpy(&tsval, &opt[2], 1898 sizeof(u_int32_t)); 1899 if (tsval && src->scrub && 1900 (src->scrub->pfss_flags & 1901 PFSS_TIMESTAMP)) { 1902 tsval = ntohl(tsval); 1903 pf_change_proto_a(m, &opt[2], 1904 &th->th_sum, 1905 htonl(tsval + 1906 src->scrub->pfss_ts_mod), 1907 0); 1908 copyback = 1; 1909 } 1910 1911 /* Modulate TS reply iff valid (!0) */ 1912 memcpy(&tsecr, &opt[6], 1913 sizeof(u_int32_t)); 1914 if (tsecr && dst->scrub && 1915 (dst->scrub->pfss_flags & 1916 PFSS_TIMESTAMP)) { 1917 tsecr = ntohl(tsecr) 1918 - dst->scrub->pfss_ts_mod; 1919 pf_change_proto_a(m, &opt[6], 1920 &th->th_sum, htonl(tsecr), 1921 0); 1922 copyback = 1; 1923 } 1924 got_ts = 1; 1925 } 1926 /* FALLTHROUGH */ 1927 default: 1928 hlen -= MAX(opt[1], 2); 1929 opt += MAX(opt[1], 2); 1930 break; 1931 } 1932 } 1933 if (copyback) { 1934 /* Copyback the options, caller copys back header */ 1935 *writeback = 1; 1936 m_copyback(m, off + sizeof(struct tcphdr), 1937 (th->th_off << 2) - sizeof(struct tcphdr), hdr + 1938 sizeof(struct tcphdr)); 1939 } 1940 } 1941 1942 1943 /* 1944 * Must invalidate PAWS checks on connections idle for too long. 1945 * The fastest allowed timestamp clock is 1ms. That turns out to 1946 * be about 24 days before it wraps. XXX Right now our lowerbound 1947 * TS echo check only works for the first 12 days of a connection 1948 * when the TS has exhausted half its 32bit space 1949 */ 1950#define TS_MAX_IDLE (24*24*60*60) 1951#define TS_MAX_CONN (12*24*60*60) /* XXX remove when better tsecr check */ 1952 1953 getmicrouptime(&uptime); 1954 if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) && 1955 (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE || 1956 time_uptime - state->creation > TS_MAX_CONN)) { 1957 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1958 DPFPRINTF(("src idled out of PAWS\n")); 1959 pf_print_state(state); 1960 printf("\n"); 1961 } 1962 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS) 1963 | PFSS_PAWS_IDLED; 1964 } 1965 if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) && 1966 uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) { 1967 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1968 DPFPRINTF(("dst idled out of PAWS\n")); 1969 pf_print_state(state); 1970 printf("\n"); 1971 } 1972 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS) 1973 | PFSS_PAWS_IDLED; 1974 } 1975 1976 if (got_ts && src->scrub && dst->scrub && 1977 (src->scrub->pfss_flags & PFSS_PAWS) && 1978 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1979 /* Validate that the timestamps are "in-window". 1980 * RFC1323 describes TCP Timestamp options that allow 1981 * measurement of RTT (round trip time) and PAWS 1982 * (protection against wrapped sequence numbers). PAWS 1983 * gives us a set of rules for rejecting packets on 1984 * long fat pipes (packets that were somehow delayed 1985 * in transit longer than the time it took to send the 1986 * full TCP sequence space of 4Gb). We can use these 1987 * rules and infer a few others that will let us treat 1988 * the 32bit timestamp and the 32bit echoed timestamp 1989 * as sequence numbers to prevent a blind attacker from 1990 * inserting packets into a connection. 1991 * 1992 * RFC1323 tells us: 1993 * - The timestamp on this packet must be greater than 1994 * or equal to the last value echoed by the other 1995 * endpoint. The RFC says those will be discarded 1996 * since it is a dup that has already been acked. 1997 * This gives us a lowerbound on the timestamp. 1998 * timestamp >= other last echoed timestamp 1999 * - The timestamp will be less than or equal to 2000 * the last timestamp plus the time between the 2001 * last packet and now. The RFC defines the max 2002 * clock rate as 1ms. We will allow clocks to be 2003 * up to 10% fast and will allow a total difference 2004 * or 30 seconds due to a route change. And this 2005 * gives us an upperbound on the timestamp. 2006 * timestamp <= last timestamp + max ticks 2007 * We have to be careful here. Windows will send an 2008 * initial timestamp of zero and then initialize it 2009 * to a random value after the 3whs; presumably to 2010 * avoid a DoS by having to call an expensive RNG 2011 * during a SYN flood. Proof MS has at least one 2012 * good security geek. 2013 * 2014 * - The TCP timestamp option must also echo the other 2015 * endpoints timestamp. The timestamp echoed is the 2016 * one carried on the earliest unacknowledged segment 2017 * on the left edge of the sequence window. The RFC 2018 * states that the host will reject any echoed 2019 * timestamps that were larger than any ever sent. 2020 * This gives us an upperbound on the TS echo. 2021 * tescr <= largest_tsval 2022 * - The lowerbound on the TS echo is a little more 2023 * tricky to determine. The other endpoint's echoed 2024 * values will not decrease. But there may be 2025 * network conditions that re-order packets and 2026 * cause our view of them to decrease. For now the 2027 * only lowerbound we can safely determine is that 2028 * the TS echo will never be less than the original 2029 * TS. XXX There is probably a better lowerbound. 2030 * Remove TS_MAX_CONN with better lowerbound check. 2031 * tescr >= other original TS 2032 * 2033 * It is also important to note that the fastest 2034 * timestamp clock of 1ms will wrap its 32bit space in 2035 * 24 days. So we just disable TS checking after 24 2036 * days of idle time. We actually must use a 12d 2037 * connection limit until we can come up with a better 2038 * lowerbound to the TS echo check. 2039 */ 2040 struct timeval delta_ts; 2041 int ts_fudge; 2042 2043 2044 /* 2045 * PFTM_TS_DIFF is how many seconds of leeway to allow 2046 * a host's timestamp. This can happen if the previous 2047 * packet got delayed in transit for much longer than 2048 * this packet. 2049 */ 2050 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0) 2051 ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF]; 2052 2053 /* Calculate max ticks since the last timestamp */ 2054#define TS_MAXFREQ 1100 /* RFC max TS freq of 1Khz + 10% skew */ 2055#define TS_MICROSECS 1000000 /* microseconds per second */ 2056 delta_ts = uptime; 2057 timevalsub(&delta_ts, &src->scrub->pfss_last); 2058 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ; 2059 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ); 2060 2061 if ((src->state >= TCPS_ESTABLISHED && 2062 dst->state >= TCPS_ESTABLISHED) && 2063 (SEQ_LT(tsval, dst->scrub->pfss_tsecr) || 2064 SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) || 2065 (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) || 2066 SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) { 2067 /* Bad RFC1323 implementation or an insertion attack. 2068 * 2069 * - Solaris 2.6 and 2.7 are known to send another ACK 2070 * after the FIN,FIN|ACK,ACK closing that carries 2071 * an old timestamp. 2072 */ 2073 2074 DPFPRINTF(("Timestamp failed %c%c%c%c\n", 2075 SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ', 2076 SEQ_GT(tsval, src->scrub->pfss_tsval + 2077 tsval_from_last) ? '1' : ' ', 2078 SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ', 2079 SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' ')); 2080 DPFPRINTF((" tsval: %u tsecr: %u +ticks: %u " 2081 "idle: %jus %lums\n", 2082 tsval, tsecr, tsval_from_last, 2083 (uintmax_t)delta_ts.tv_sec, 2084 delta_ts.tv_usec / 1000)); 2085 DPFPRINTF((" src->tsval: %u tsecr: %u\n", 2086 src->scrub->pfss_tsval, src->scrub->pfss_tsecr)); 2087 DPFPRINTF((" dst->tsval: %u tsecr: %u tsval0: %u" 2088 "\n", dst->scrub->pfss_tsval, 2089 dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0)); 2090 if (V_pf_status.debug >= PF_DEBUG_MISC) { 2091 pf_print_state(state); 2092 pf_print_flags(th->th_flags); 2093 printf("\n"); 2094 } 2095 REASON_SET(reason, PFRES_TS); 2096 return (PF_DROP); 2097 } 2098 2099 /* XXX I'd really like to require tsecr but it's optional */ 2100 2101 } else if (!got_ts && (th->th_flags & TH_RST) == 0 && 2102 ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED) 2103 || pd->p_len > 0 || (th->th_flags & TH_SYN)) && 2104 src->scrub && dst->scrub && 2105 (src->scrub->pfss_flags & PFSS_PAWS) && 2106 (dst->scrub->pfss_flags & PFSS_PAWS)) { 2107 /* Didn't send a timestamp. Timestamps aren't really useful 2108 * when: 2109 * - connection opening or closing (often not even sent). 2110 * but we must not let an attacker to put a FIN on a 2111 * data packet to sneak it through our ESTABLISHED check. 2112 * - on a TCP reset. RFC suggests not even looking at TS. 2113 * - on an empty ACK. The TS will not be echoed so it will 2114 * probably not help keep the RTT calculation in sync and 2115 * there isn't as much danger when the sequence numbers 2116 * got wrapped. So some stacks don't include TS on empty 2117 * ACKs :-( 2118 * 2119 * To minimize the disruption to mostly RFC1323 conformant 2120 * stacks, we will only require timestamps on data packets. 2121 * 2122 * And what do ya know, we cannot require timestamps on data 2123 * packets. There appear to be devices that do legitimate 2124 * TCP connection hijacking. There are HTTP devices that allow 2125 * a 3whs (with timestamps) and then buffer the HTTP request. 2126 * If the intermediate device has the HTTP response cache, it 2127 * will spoof the response but not bother timestamping its 2128 * packets. So we can look for the presence of a timestamp in 2129 * the first data packet and if there, require it in all future 2130 * packets. 2131 */ 2132 2133 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) { 2134 /* 2135 * Hey! Someone tried to sneak a packet in. Or the 2136 * stack changed its RFC1323 behavior?!?! 2137 */ 2138 if (V_pf_status.debug >= PF_DEBUG_MISC) { 2139 DPFPRINTF(("Did not receive expected RFC1323 " 2140 "timestamp\n")); 2141 pf_print_state(state); 2142 pf_print_flags(th->th_flags); 2143 printf("\n"); 2144 } 2145 REASON_SET(reason, PFRES_TS); 2146 return (PF_DROP); 2147 } 2148 } 2149 2150 2151 /* 2152 * We will note if a host sends his data packets with or without 2153 * timestamps. And require all data packets to contain a timestamp 2154 * if the first does. PAWS implicitly requires that all data packets be 2155 * timestamped. But I think there are middle-man devices that hijack 2156 * TCP streams immediately after the 3whs and don't timestamp their 2157 * packets (seen in a WWW accelerator or cache). 2158 */ 2159 if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags & 2160 (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) { 2161 if (got_ts) 2162 src->scrub->pfss_flags |= PFSS_DATA_TS; 2163 else { 2164 src->scrub->pfss_flags |= PFSS_DATA_NOTS; 2165 if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub && 2166 (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) { 2167 /* Don't warn if other host rejected RFC1323 */ 2168 DPFPRINTF(("Broken RFC1323 stack did not " 2169 "timestamp data packet. Disabled PAWS " 2170 "security.\n")); 2171 pf_print_state(state); 2172 pf_print_flags(th->th_flags); 2173 printf("\n"); 2174 } 2175 } 2176 } 2177 2178 2179 /* 2180 * Update PAWS values 2181 */ 2182 if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags & 2183 (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) { 2184 getmicrouptime(&src->scrub->pfss_last); 2185 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) || 2186 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 2187 src->scrub->pfss_tsval = tsval; 2188 2189 if (tsecr) { 2190 if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) || 2191 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 2192 src->scrub->pfss_tsecr = tsecr; 2193 2194 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 && 2195 (SEQ_LT(tsval, src->scrub->pfss_tsval0) || 2196 src->scrub->pfss_tsval0 == 0)) { 2197 /* tsval0 MUST be the lowest timestamp */ 2198 src->scrub->pfss_tsval0 = tsval; 2199 } 2200 2201 /* Only fully initialized after a TS gets echoed */ 2202 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0) 2203 src->scrub->pfss_flags |= PFSS_PAWS; 2204 } 2205 } 2206 2207 /* I have a dream.... TCP segment reassembly.... */ 2208 return (0); 2209} 2210 2211static int 2212pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th, 2213 int off, sa_family_t af) 2214{ 2215 u_int16_t *mss; 2216 int thoff; 2217 int opt, cnt, optlen = 0; 2218 int rewrite = 0; 2219 u_char opts[TCP_MAXOLEN]; 2220 u_char *optp = opts; 2221 2222 thoff = th->th_off << 2; 2223 cnt = thoff - sizeof(struct tcphdr); 2224 2225 if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt, 2226 NULL, NULL, af)) 2227 return (rewrite); 2228 2229 for (; cnt > 0; cnt -= optlen, optp += optlen) { 2230 opt = optp[0]; 2231 if (opt == TCPOPT_EOL) 2232 break; 2233 if (opt == TCPOPT_NOP) 2234 optlen = 1; 2235 else { 2236 if (cnt < 2) 2237 break; 2238 optlen = optp[1]; 2239 if (optlen < 2 || optlen > cnt) 2240 break; 2241 } 2242 switch (opt) { 2243 case TCPOPT_MAXSEG: 2244 mss = (u_int16_t *)(optp + 2); 2245 if ((ntohs(*mss)) > r->max_mss) { 2246 th->th_sum = pf_proto_cksum_fixup(m, 2247 th->th_sum, *mss, htons(r->max_mss), 0); 2248 *mss = htons(r->max_mss); 2249 rewrite = 1; 2250 } 2251 break; 2252 default: 2253 break; 2254 } 2255 } 2256 2257 if (rewrite) 2258 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts); 2259 2260 return (rewrite); 2261} 2262 2263#ifdef INET 2264static void 2265pf_scrub_ip(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos) 2266{ 2267 struct mbuf *m = *m0; 2268 struct ip *h = mtod(m, struct ip *); 2269 2270 /* Clear IP_DF if no-df was requested */ 2271 if (flags & PFRULE_NODF && h->ip_off & htons(IP_DF)) { 2272 u_int16_t ip_off = h->ip_off; 2273 2274 h->ip_off &= htons(~IP_DF); 2275 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 2276 } 2277 2278 /* Enforce a minimum ttl, may cause endless packet loops */ 2279 if (min_ttl && h->ip_ttl < min_ttl) { 2280 u_int16_t ip_ttl = h->ip_ttl; 2281 2282 h->ip_ttl = min_ttl; 2283 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0); 2284 } 2285 2286 /* Enforce tos */ 2287 if (flags & PFRULE_SET_TOS) { 2288 u_int16_t ov, nv; 2289 2290 ov = *(u_int16_t *)h; 2291 h->ip_tos = tos; 2292 nv = *(u_int16_t *)h; 2293 2294 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0); 2295 } 2296 2297 /* random-id, but not for fragments */ 2298 if (flags & PFRULE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) { 2299 u_int16_t ip_id = h->ip_id; 2300 2301 h->ip_id = ip_randomid(); 2302 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0); 2303 } 2304} 2305#endif /* INET */ 2306 2307#ifdef INET6 2308static void 2309pf_scrub_ip6(struct mbuf **m0, u_int8_t min_ttl) 2310{ 2311 struct mbuf *m = *m0; 2312 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 2313 2314 /* Enforce a minimum ttl, may cause endless packet loops */ 2315 if (min_ttl && h->ip6_hlim < min_ttl) 2316 h->ip6_hlim = min_ttl; 2317} 2318#endif 2319