pf_norm.c revision 284572
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 284572 2015-06-18 20:40:36Z 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 uint8_t frc_direction; 79}; 80 81struct 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#define fr_direction fr_key.frc_direction 89 90 RB_ENTRY(pf_fragment) fr_entry; 91 TAILQ_ENTRY(pf_fragment) frag_next; 92 uint8_t fr_flags; /* status flags */ 93#define PFFRAG_SEENLAST 0x0001 /* Seen the last fragment for this */ 94#define PFFRAG_NOBUFFER 0x0002 /* Non-buffering fragment cache */ 95#define PFFRAG_DROP 0x0004 /* Drop all fragments */ 96#define BUFFER_FRAGMENTS(fr) (!((fr)->fr_flags & PFFRAG_NOBUFFER)) 97 uint16_t fr_max; /* fragment data max */ 98 uint32_t fr_timeout; 99 uint16_t fr_maxlen; /* maximum length of single fragment */ 100 TAILQ_HEAD(pf_fragq, pf_frent) fr_queue; 101}; 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); 137 138/* Private prototypes */ 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); 143#ifdef INET 144static void pf_scrub_ip(struct mbuf **, u_int32_t, u_int8_t, 145 u_int8_t); 146static void pf_flush_fragments(void); 147static struct pf_fragment *pf_find_fragment(struct pf_fragment_cmp *key, 148 struct pf_frag_tree *tree); 149struct pf_frent *pf_create_fragment(u_short *); 150static int pf_reassemble(struct mbuf **, struct ip *, int, 151 u_short *); 152int pf_reassemble6(struct mbuf **, struct ip6_hdr *, 153 struct ip6_frag *, uint16_t, uint16_t, int, 154 u_short *); 155static struct mbuf *pf_fragcache(struct mbuf **, struct ip*, 156 struct pf_fragment **, int, int, int *); 157static struct pf_fragment *pf_fillup_fragment(struct pf_fragment_cmp *, 158 struct pf_frent *, u_short *); 159int pf_isfull_fragment(struct pf_fragment *); 160struct mbuf *pf_join_fragment(struct pf_fragment *); 161 162 163#endif /* INET */ 164#ifdef INET6 165static void pf_scrub_ip6(struct mbuf **, u_int8_t); 166#endif 167#define DPFPRINTF(x) do { \ 168 if (V_pf_status.debug >= PF_DEBUG_MISC) { \ 169 printf("%s: ", __func__); \ 170 printf x ; \ 171 } \ 172} while(0) 173 174static void 175pf_ip2key(struct ip *ip, int dir, struct pf_fragment_cmp *key) 176{ 177 178 key->frc_src.v4 = ip->ip_src; 179 key->frc_dst.v4 = ip->ip_dst; 180 key->frc_af = AF_INET; 181 key->frc_proto = ip->ip_p; 182 key->frc_id = ip->ip_id; 183 key->frc_direction = dir; 184} 185 186void 187pf_normalize_init(void) 188{ 189 190 V_pf_frag_z = uma_zcreate("pf frags", sizeof(struct pf_fragment), 191 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 192 V_pf_frent_z = uma_zcreate("pf frag entries", sizeof(struct pf_frent), 193 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 194 V_pf_state_scrub_z = uma_zcreate("pf state scrubs", 195 sizeof(struct pf_state_scrub), NULL, NULL, NULL, NULL, 196 UMA_ALIGN_PTR, 0); 197 198 V_pf_limits[PF_LIMIT_FRAGS].zone = V_pf_frent_z; 199 V_pf_limits[PF_LIMIT_FRAGS].limit = PFFRAG_FRENT_HIWAT; 200 uma_zone_set_max(V_pf_frent_z, PFFRAG_FRENT_HIWAT); 201 uma_zone_set_warning(V_pf_frent_z, "PF frag entries limit reached"); 202 203 mtx_init(&pf_frag_mtx, "pf fragments", NULL, MTX_DEF); 204 205 TAILQ_INIT(&V_pf_fragqueue); 206 TAILQ_INIT(&V_pf_cachequeue); 207} 208 209void 210pf_normalize_cleanup(void) 211{ 212 213 uma_zdestroy(V_pf_state_scrub_z); 214 uma_zdestroy(V_pf_frent_z); 215 uma_zdestroy(V_pf_frag_z); 216 217 mtx_destroy(&pf_frag_mtx); 218} 219 220static int 221pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b) 222{ 223 int diff; 224 225 if ((diff = a->fr_id - b->fr_id) != 0) 226 return (diff); 227 if ((diff = a->fr_proto - b->fr_proto) != 0) 228 return (diff); 229 if ((diff = a->fr_af - b->fr_af) != 0) 230 return (diff); 231 if ((diff = pf_addr_cmp(&a->fr_src, &b->fr_src, a->fr_af)) != 0) 232 return (diff); 233 if ((diff = pf_addr_cmp(&a->fr_dst, &b->fr_dst, a->fr_af)) != 0) 234 return (diff); 235 return (0); 236} 237 238void 239pf_purge_expired_fragments(void) 240{ 241 struct pf_fragment *frag; 242 u_int32_t expire = time_uptime - 243 V_pf_default_rule.timeout[PFTM_FRAG]; 244 245 PF_FRAG_LOCK(); 246 while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) { 247 KASSERT((BUFFER_FRAGMENTS(frag)), 248 ("BUFFER_FRAGMENTS(frag) == 0: %s", __FUNCTION__)); 249 if (frag->fr_timeout > expire) 250 break; 251 252 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); 253 pf_free_fragment(frag); 254 } 255 256 while ((frag = TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue)) != NULL) { 257 KASSERT((!BUFFER_FRAGMENTS(frag)), 258 ("BUFFER_FRAGMENTS(frag) != 0: %s", __FUNCTION__)); 259 if (frag->fr_timeout > expire) 260 break; 261 262 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag)); 263 pf_free_fragment(frag); 264 KASSERT((TAILQ_EMPTY(&V_pf_cachequeue) || 265 TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue) != frag), 266 ("!(TAILQ_EMPTY() || TAILQ_LAST() == farg): %s", 267 __FUNCTION__)); 268 } 269 PF_FRAG_UNLOCK(); 270} 271 272#ifdef INET 273/* 274 * Try to flush old fragments to make space for new ones 275 */ 276static void 277pf_flush_fragments(void) 278{ 279 struct pf_fragment *frag, *cache; 280 int goal; 281 282 PF_FRAG_ASSERT(); 283 284 goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10; 285 DPFPRINTF(("trying to free %d frag entriess\n", goal)); 286 while (goal < uma_zone_get_cur(V_pf_frent_z)) { 287 frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue); 288 if (frag) 289 pf_free_fragment(frag); 290 cache = TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue); 291 if (cache) 292 pf_free_fragment(cache); 293 if (frag == NULL && cache == NULL) 294 break; 295 } 296} 297#endif /* INET */ 298 299/* Frees the fragments and all associated entries */ 300static void 301pf_free_fragment(struct pf_fragment *frag) 302{ 303 struct pf_frent *frent; 304 305 PF_FRAG_ASSERT(); 306 307 /* Free all fragments */ 308 if (BUFFER_FRAGMENTS(frag)) { 309 for (frent = TAILQ_FIRST(&frag->fr_queue); frent; 310 frent = TAILQ_FIRST(&frag->fr_queue)) { 311 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 312 313 m_freem(frent->fe_m); 314 uma_zfree(V_pf_frent_z, frent); 315 } 316 } else { 317 for (frent = TAILQ_FIRST(&frag->fr_queue); frent; 318 frent = TAILQ_FIRST(&frag->fr_queue)) { 319 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next); 320 321 KASSERT((TAILQ_EMPTY(&frag->fr_queue) || 322 TAILQ_FIRST(&frag->fr_queue)->fe_off > 323 frent->fe_len), 324 ("! (TAILQ_EMPTY() || TAILQ_FIRST()->fe_off >" 325 " frent->fe_len): %s", __func__)); 326 327 uma_zfree(V_pf_frent_z, frent); 328 } 329 } 330 331 pf_remove_fragment(frag); 332} 333 334#ifdef INET 335static struct pf_fragment * 336pf_find_fragment(struct pf_fragment_cmp *key, struct pf_frag_tree *tree) 337{ 338 struct pf_fragment *frag; 339 340 PF_FRAG_ASSERT(); 341 342 frag = RB_FIND(pf_frag_tree, tree, (struct pf_fragment *)key); 343 if (frag != NULL) { 344 /* XXX Are we sure we want to update the timeout? */ 345 frag->fr_timeout = time_uptime; 346 if (BUFFER_FRAGMENTS(frag)) { 347 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next); 348 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next); 349 } else { 350 TAILQ_REMOVE(&V_pf_cachequeue, frag, frag_next); 351 TAILQ_INSERT_HEAD(&V_pf_cachequeue, frag, frag_next); 352 } 353 } 354 355 return (frag); 356} 357#endif /* INET */ 358 359/* Removes a fragment from the fragment queue and frees the fragment */ 360 361static void 362pf_remove_fragment(struct pf_fragment *frag) 363{ 364 365 PF_FRAG_ASSERT(); 366 367 if (BUFFER_FRAGMENTS(frag)) { 368 RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag); 369 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next); 370 uma_zfree(V_pf_frag_z, frag); 371 } else { 372 RB_REMOVE(pf_frag_tree, &V_pf_cache_tree, frag); 373 TAILQ_REMOVE(&V_pf_cachequeue, frag, frag_next); 374 uma_zfree(V_pf_frag_z, frag); 375 } 376} 377 378#ifdef INET 379struct pf_frent * 380pf_create_fragment(u_short *reason) 381{ 382 struct pf_frent *frent; 383 384 PF_FRAG_ASSERT(); 385 386 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT); 387 if (frent == NULL) { 388 pf_flush_fragments(); 389 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT); 390 if (frent == NULL) { 391 REASON_SET(reason, PFRES_MEMORY); 392 return (NULL); 393 } 394 } 395 396 return (frent); 397} 398 399struct pf_fragment * 400pf_fillup_fragment(struct pf_fragment_cmp *key, struct pf_frent *frent, 401 u_short *reason) 402{ 403 struct pf_frent *after, *next, *prev; 404 struct pf_fragment *frag; 405 uint16_t total; 406 407 PF_FRAG_ASSERT(); 408 409 /* No empty fragments. */ 410 if (frent->fe_len == 0) { 411 DPFPRINTF(("bad fragment: len 0")); 412 goto bad_fragment; 413 } 414 415 /* All fragments are 8 byte aligned. */ 416 if (frent->fe_mff && (frent->fe_len & 0x7)) { 417 DPFPRINTF(("bad fragment: mff and len %d", frent->fe_len)); 418 goto bad_fragment; 419 } 420 421 /* Respect maximum length, IP_MAXPACKET == IPV6_MAXPACKET. */ 422 if (frent->fe_off + frent->fe_len > IP_MAXPACKET) { 423 DPFPRINTF(("bad fragment: max packet %d", 424 frent->fe_off + frent->fe_len)); 425 goto bad_fragment; 426 } 427 428 DPFPRINTF((key->frc_af == AF_INET ? 429 "reass frag %d @ %d-%d" : "reass frag %#08x @ %d-%d", 430 key->frc_id, frent->fe_off, frent->fe_off + frent->fe_len)); 431 432 /* Fully buffer all of the fragments in this fragment queue. */ 433 frag = pf_find_fragment(key, &V_pf_frag_tree); 434 435 /* Create a new reassembly queue for this packet. */ 436 if (frag == NULL) { 437 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 438 if (frag == NULL) { 439 pf_flush_fragments(); 440 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 441 if (frag == NULL) { 442 REASON_SET(reason, PFRES_MEMORY); 443 goto drop_fragment; 444 } 445 } 446 447 *(struct pf_fragment_cmp *)frag = *key; 448 frag->fr_timeout = time_second; 449 frag->fr_maxlen = frent->fe_len; 450 TAILQ_INIT(&frag->fr_queue); 451 452 RB_INSERT(pf_frag_tree, &V_pf_frag_tree, frag); 453 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next); 454 455 /* We do not have a previous fragment. */ 456 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next); 457 458 return (frag); 459 } 460 461 KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue")); 462 463 /* Remember maximum fragment len for refragmentation. */ 464 if (frent->fe_len > frag->fr_maxlen) 465 frag->fr_maxlen = frent->fe_len; 466 467 /* Maximum data we have seen already. */ 468 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 469 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 470 471 /* Non terminal fragments must have more fragments flag. */ 472 if (frent->fe_off + frent->fe_len < total && !frent->fe_mff) 473 goto bad_fragment; 474 475 /* Check if we saw the last fragment already. */ 476 if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) { 477 if (frent->fe_off + frent->fe_len > total || 478 (frent->fe_off + frent->fe_len == total && frent->fe_mff)) 479 goto bad_fragment; 480 } else { 481 if (frent->fe_off + frent->fe_len == total && !frent->fe_mff) 482 goto bad_fragment; 483 } 484 485 /* Find a fragment after the current one. */ 486 prev = NULL; 487 TAILQ_FOREACH(after, &frag->fr_queue, fr_next) { 488 if (after->fe_off > frent->fe_off) 489 break; 490 prev = after; 491 } 492 493 KASSERT(prev != NULL || after != NULL, 494 ("prev != NULL || after != NULL")); 495 496 if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) { 497 uint16_t precut; 498 499 precut = prev->fe_off + prev->fe_len - frent->fe_off; 500 if (precut >= frent->fe_len) 501 goto bad_fragment; 502 DPFPRINTF(("overlap -%d", precut)); 503 m_adj(frent->fe_m, precut); 504 frent->fe_off += precut; 505 frent->fe_len -= precut; 506 } 507 508 for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off; 509 after = next) { 510 uint16_t aftercut; 511 512 aftercut = frent->fe_off + frent->fe_len - after->fe_off; 513 DPFPRINTF(("adjust overlap %d", aftercut)); 514 if (aftercut < after->fe_len) { 515 m_adj(after->fe_m, aftercut); 516 after->fe_off += aftercut; 517 after->fe_len -= aftercut; 518 break; 519 } 520 521 /* This fragment is completely overlapped, lose it. */ 522 next = TAILQ_NEXT(after, fr_next); 523 m_freem(after->fe_m); 524 TAILQ_REMOVE(&frag->fr_queue, after, fr_next); 525 uma_zfree(V_pf_frent_z, after); 526 } 527 528 if (prev == NULL) 529 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next); 530 else 531 TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next); 532 533 return (frag); 534 535bad_fragment: 536 REASON_SET(reason, PFRES_FRAG); 537drop_fragment: 538 uma_zfree(V_pf_frent_z, frent); 539 return (NULL); 540} 541 542int 543pf_isfull_fragment(struct pf_fragment *frag) 544{ 545 struct pf_frent *frent, *next; 546 uint16_t off, total; 547 548 /* Check if we are completely reassembled */ 549 if (TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) 550 return (0); 551 552 /* Maximum data we have seen already */ 553 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 554 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 555 556 /* Check if we have all the data */ 557 off = 0; 558 for (frent = TAILQ_FIRST(&frag->fr_queue); frent; frent = next) { 559 next = TAILQ_NEXT(frent, fr_next); 560 561 off += frent->fe_len; 562 if (off < total && (next == NULL || next->fe_off != off)) { 563 DPFPRINTF(("missing fragment at %d, next %d, total %d", 564 off, next == NULL ? -1 : next->fe_off, total)); 565 return (0); 566 } 567 } 568 DPFPRINTF(("%d < %d?", off, total)); 569 if (off < total) 570 return (0); 571 KASSERT(off == total, ("off == total")); 572 573 return (1); 574} 575 576struct mbuf * 577pf_join_fragment(struct pf_fragment *frag) 578{ 579 struct mbuf *m, *m2; 580 struct pf_frent *frent, *next; 581 582 frent = TAILQ_FIRST(&frag->fr_queue); 583 next = TAILQ_NEXT(frent, fr_next); 584 585 /* Magic from ip_input. */ 586 m = frent->fe_m; 587 m2 = m->m_next; 588 m->m_next = NULL; 589 m_cat(m, m2); 590 uma_zfree(V_pf_frent_z, frent); 591 for (frent = next; frent != NULL; frent = next) { 592 next = TAILQ_NEXT(frent, fr_next); 593 594 m2 = frent->fe_m; 595 /* Strip off ip header. */ 596 m_adj(m2, frent->fe_hdrlen); 597 uma_zfree(V_pf_frent_z, frent); 598 m_cat(m, m2); 599 } 600 601 /* Remove from fragment queue. */ 602 pf_remove_fragment(frag); 603 604 return (m); 605} 606 607#define FR_IP_OFF(fr) ((ntohs((fr)->fr_ip->ip_off) & IP_OFFMASK) << 3) 608static int 609pf_reassemble(struct mbuf **m0, struct ip *ip, int dir, u_short *reason) 610{ 611 struct mbuf *m = *m0; 612 struct pf_frent *frent; 613 struct pf_fragment *frag; 614 struct pf_fragment_cmp key; 615 uint16_t total, hdrlen; 616 617 /* Get an entry for the fragment queue */ 618 if ((frent = pf_create_fragment(reason)) == NULL) 619 return (PF_DROP); 620 621 frent->fe_m = m; 622 frent->fe_hdrlen = ip->ip_hl << 2; 623 frent->fe_extoff = 0; 624 frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2); 625 frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3; 626 frent->fe_mff = ntohs(ip->ip_off) & IP_MF; 627 628 pf_ip2key(ip, dir, &key); 629 630 if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) 631 return (PF_DROP); 632 633 /* The mbuf is part of the fragment entry, no direct free or access */ 634 m = *m0 = NULL; 635 636 if (!pf_isfull_fragment(frag)) 637 return (PF_PASS); /* drop because *m0 is NULL, no error */ 638 639 /* We have all the data */ 640 frent = TAILQ_FIRST(&frag->fr_queue); 641 KASSERT(frent != NULL, ("frent != NULL")); 642 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 643 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 644 hdrlen = frent->fe_hdrlen; 645 646 m = *m0 = pf_join_fragment(frag); 647 frag = NULL; 648 649 if (m->m_flags & M_PKTHDR) { 650 int plen = 0; 651 for (m = *m0; m; m = m->m_next) 652 plen += m->m_len; 653 m = *m0; 654 m->m_pkthdr.len = plen; 655 } 656 657 ip = mtod(m, struct ip *); 658 ip->ip_len = htons(hdrlen + total); 659 ip->ip_off &= ~(IP_MF|IP_OFFMASK); 660 661 if (hdrlen + total > IP_MAXPACKET) { 662 DPFPRINTF(("drop: too big: %d", total)); 663 ip->ip_len = 0; 664 REASON_SET(reason, PFRES_SHORT); 665 /* PF_DROP requires a valid mbuf *m0 in pf_test() */ 666 return (PF_DROP); 667 } 668 669 DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len))); 670 return (PF_PASS); 671} 672 673#ifdef INET6 674int 675pf_reassemble6(struct mbuf **m0, struct ip6_hdr *ip6, struct ip6_frag *fraghdr, 676 uint16_t hdrlen, uint16_t extoff, int dir, u_short *reason) 677{ 678 struct mbuf *m = *m0; 679 struct pf_frent *frent; 680 struct pf_fragment *frag; 681 struct pf_fragment_cmp key; 682 struct m_tag *mtag; 683 struct pf_fragment_tag *ftag; 684 int off; 685 uint32_t frag_id; 686 uint16_t total, maxlen; 687 uint8_t proto; 688 689 PF_FRAG_LOCK(); 690 691 /* Get an entry for the fragment queue. */ 692 if ((frent = pf_create_fragment(reason)) == NULL) { 693 PF_FRAG_UNLOCK(); 694 return (PF_DROP); 695 } 696 697 frent->fe_m = m; 698 frent->fe_hdrlen = hdrlen; 699 frent->fe_extoff = extoff; 700 frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen; 701 frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK); 702 frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG; 703 704 key.frc_src.v6 = ip6->ip6_src; 705 key.frc_dst.v6 = ip6->ip6_dst; 706 key.frc_af = AF_INET6; 707 /* Only the first fragment's protocol is relevant. */ 708 key.frc_proto = 0; 709 key.frc_id = fraghdr->ip6f_ident; 710 key.frc_direction = dir; 711 712 if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) { 713 PF_FRAG_UNLOCK(); 714 return (PF_DROP); 715 } 716 717 /* The mbuf is part of the fragment entry, no direct free or access. */ 718 m = *m0 = NULL; 719 720 if (!pf_isfull_fragment(frag)) { 721 PF_FRAG_UNLOCK(); 722 return (PF_PASS); /* Drop because *m0 is NULL, no error. */ 723 } 724 725 /* We have all the data. */ 726 extoff = frent->fe_extoff; 727 maxlen = frag->fr_maxlen; 728 frag_id = frag->fr_id; 729 frent = TAILQ_FIRST(&frag->fr_queue); 730 KASSERT(frent != NULL, ("frent != NULL")); 731 total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + 732 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; 733 hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag); 734 735 m = *m0 = pf_join_fragment(frag); 736 frag = NULL; 737 738 PF_FRAG_UNLOCK(); 739 740 /* Take protocol from first fragment header. */ 741 m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off); 742 KASSERT(m, ("%s: short mbuf chain", __func__)); 743 proto = *(mtod(m, caddr_t) + off); 744 m = *m0; 745 746 /* Delete frag6 header */ 747 if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0) 748 goto fail; 749 750 if (m->m_flags & M_PKTHDR) { 751 int plen = 0; 752 for (m = *m0; m; m = m->m_next) 753 plen += m->m_len; 754 m = *m0; 755 m->m_pkthdr.len = plen; 756 } 757 758 if ((mtag = m_tag_get(PF_REASSEMBLED, sizeof(struct pf_fragment_tag), 759 M_NOWAIT)) == NULL) 760 goto fail; 761 ftag = (struct pf_fragment_tag *)(mtag + 1); 762 ftag->ft_hdrlen = hdrlen; 763 ftag->ft_extoff = extoff; 764 ftag->ft_maxlen = maxlen; 765 ftag->ft_id = frag_id; 766 m_tag_prepend(m, mtag); 767 768 ip6 = mtod(m, struct ip6_hdr *); 769 ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total); 770 if (extoff) { 771 /* Write protocol into next field of last extension header. */ 772 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt), 773 &off); 774 KASSERT(m, ("%s: short mbuf chain", __func__)); 775 *(mtod(m, char *) + off) = proto; 776 m = *m0; 777 } else 778 ip6->ip6_nxt = proto; 779 780 if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) { 781 DPFPRINTF(("drop: too big: %d", total)); 782 ip6->ip6_plen = 0; 783 REASON_SET(reason, PFRES_SHORT); 784 /* PF_DROP requires a valid mbuf *m0 in pf_test6(). */ 785 return (PF_DROP); 786 } 787 788 DPFPRINTF(("complete: %p(%d)", m, ntohs(ip6->ip6_plen))); 789 return (PF_PASS); 790 791fail: 792 REASON_SET(reason, PFRES_MEMORY); 793 /* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */ 794 return (PF_DROP); 795} 796 797#endif 798 799static struct mbuf * 800pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff, 801 int drop, int *nomem) 802{ 803 struct mbuf *m = *m0; 804 struct pf_frent *frp, *fra, *cur = NULL; 805 int ip_len = ntohs(h->ip_len) - (h->ip_hl << 2); 806 u_int16_t off = ntohs(h->ip_off) << 3; 807 u_int16_t max = ip_len + off; 808 int hosed = 0; 809 810 PF_FRAG_ASSERT(); 811 KASSERT((*frag == NULL || !BUFFER_FRAGMENTS(*frag)), 812 ("!(*frag == NULL || !BUFFER_FRAGMENTS(*frag)): %s", __FUNCTION__)); 813 814 /* Create a new range queue for this packet */ 815 if (*frag == NULL) { 816 *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 817 if (*frag == NULL) { 818 pf_flush_fragments(); 819 *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT); 820 if (*frag == NULL) 821 goto no_mem; 822 } 823 824 /* Get an entry for the queue */ 825 cur = uma_zalloc(V_pf_frent_z, M_NOWAIT); 826 if (cur == NULL) { 827 uma_zfree(V_pf_frag_z, *frag); 828 *frag = NULL; 829 goto no_mem; 830 } 831 832 (*frag)->fr_flags = PFFRAG_NOBUFFER; 833 (*frag)->fr_max = 0; 834 (*frag)->fr_src.v4 = h->ip_src; 835 (*frag)->fr_dst.v4 = h->ip_dst; 836 (*frag)->fr_id = h->ip_id; 837 (*frag)->fr_timeout = time_uptime; 838 839 cur->fe_off = off; 840 cur->fe_len = max; /* TODO: fe_len = max - off ? */ 841 TAILQ_INIT(&(*frag)->fr_queue); 842 TAILQ_INSERT_HEAD(&(*frag)->fr_queue, cur, fr_next); 843 844 RB_INSERT(pf_frag_tree, &V_pf_cache_tree, *frag); 845 TAILQ_INSERT_HEAD(&V_pf_cachequeue, *frag, frag_next); 846 847 DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max)); 848 849 goto pass; 850 } 851 852 /* 853 * Find a fragment after the current one: 854 * - off contains the real shifted offset. 855 */ 856 frp = NULL; 857 TAILQ_FOREACH(fra, &(*frag)->fr_queue, fr_next) { 858 if (fra->fe_off > off) 859 break; 860 frp = fra; 861 } 862 863 KASSERT((frp != NULL || fra != NULL), 864 ("!(frp != NULL || fra != NULL): %s", __FUNCTION__)); 865 866 if (frp != NULL) { 867 int precut; 868 869 precut = frp->fe_len - off; 870 if (precut >= ip_len) { 871 /* Fragment is entirely a duplicate */ 872 DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n", 873 h->ip_id, frp->fe_off, frp->fe_len, off, max)); 874 goto drop_fragment; 875 } 876 if (precut == 0) { 877 /* They are adjacent. Fixup cache entry */ 878 DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n", 879 h->ip_id, frp->fe_off, frp->fe_len, off, max)); 880 frp->fe_len = max; 881 } else if (precut > 0) { 882 /* The first part of this payload overlaps with a 883 * fragment that has already been passed. 884 * Need to trim off the first part of the payload. 885 * But to do so easily, we need to create another 886 * mbuf to throw the original header into. 887 */ 888 889 DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n", 890 h->ip_id, precut, frp->fe_off, frp->fe_len, off, 891 max)); 892 893 off += precut; 894 max -= precut; 895 /* Update the previous frag to encompass this one */ 896 frp->fe_len = max; 897 898 if (!drop) { 899 /* XXX Optimization opportunity 900 * This is a very heavy way to trim the payload. 901 * we could do it much faster by diddling mbuf 902 * internals but that would be even less legible 903 * than this mbuf magic. For my next trick, 904 * I'll pull a rabbit out of my laptop. 905 */ 906 *m0 = m_dup(m, M_NOWAIT); 907 if (*m0 == NULL) 908 goto no_mem; 909 /* From KAME Project : We have missed this! */ 910 m_adj(*m0, (h->ip_hl << 2) - 911 (*m0)->m_pkthdr.len); 912 913 KASSERT(((*m0)->m_next == NULL), 914 ("(*m0)->m_next != NULL: %s", 915 __FUNCTION__)); 916 m_adj(m, precut + (h->ip_hl << 2)); 917 m_cat(*m0, m); 918 m = *m0; 919 if (m->m_flags & M_PKTHDR) { 920 int plen = 0; 921 struct mbuf *t; 922 for (t = m; t; t = t->m_next) 923 plen += t->m_len; 924 m->m_pkthdr.len = plen; 925 } 926 927 928 h = mtod(m, struct ip *); 929 930 KASSERT(((int)m->m_len == 931 ntohs(h->ip_len) - precut), 932 ("m->m_len != ntohs(h->ip_len) - precut: %s", 933 __FUNCTION__)); 934 h->ip_off = htons(ntohs(h->ip_off) + 935 (precut >> 3)); 936 h->ip_len = htons(ntohs(h->ip_len) - precut); 937 } else { 938 hosed++; 939 } 940 } else { 941 /* There is a gap between fragments */ 942 943 DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n", 944 h->ip_id, -precut, frp->fe_off, frp->fe_len, off, 945 max)); 946 947 cur = uma_zalloc(V_pf_frent_z, M_NOWAIT); 948 if (cur == NULL) 949 goto no_mem; 950 951 cur->fe_off = off; 952 cur->fe_len = max; 953 TAILQ_INSERT_AFTER(&(*frag)->fr_queue, frp, cur, fr_next); 954 } 955 } 956 957 if (fra != NULL) { 958 int aftercut; 959 int merge = 0; 960 961 aftercut = max - fra->fe_off; 962 if (aftercut == 0) { 963 /* Adjacent fragments */ 964 DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n", 965 h->ip_id, off, max, fra->fe_off, fra->fe_len)); 966 fra->fe_off = off; 967 merge = 1; 968 } else if (aftercut > 0) { 969 /* Need to chop off the tail of this fragment */ 970 DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n", 971 h->ip_id, aftercut, off, max, fra->fe_off, 972 fra->fe_len)); 973 fra->fe_off = off; 974 max -= aftercut; 975 976 merge = 1; 977 978 if (!drop) { 979 m_adj(m, -aftercut); 980 if (m->m_flags & M_PKTHDR) { 981 int plen = 0; 982 struct mbuf *t; 983 for (t = m; t; t = t->m_next) 984 plen += t->m_len; 985 m->m_pkthdr.len = plen; 986 } 987 h = mtod(m, struct ip *); 988 KASSERT(((int)m->m_len == ntohs(h->ip_len) - aftercut), 989 ("m->m_len != ntohs(h->ip_len) - aftercut: %s", 990 __FUNCTION__)); 991 h->ip_len = htons(ntohs(h->ip_len) - aftercut); 992 } else { 993 hosed++; 994 } 995 } else if (frp == NULL) { 996 /* There is a gap between fragments */ 997 DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n", 998 h->ip_id, -aftercut, off, max, fra->fe_off, 999 fra->fe_len)); 1000 1001 cur = uma_zalloc(V_pf_frent_z, M_NOWAIT); 1002 if (cur == NULL) 1003 goto no_mem; 1004 1005 cur->fe_off = off; 1006 cur->fe_len = max; 1007 TAILQ_INSERT_HEAD(&(*frag)->fr_queue, cur, fr_next); 1008 } 1009 1010 1011 /* Need to glue together two separate fragment descriptors */ 1012 if (merge) { 1013 if (cur && fra->fe_off <= cur->fe_len) { 1014 /* Need to merge in a previous 'cur' */ 1015 DPFPRINTF(("fragcache[%d]: adjacent(merge " 1016 "%d-%d) %d-%d (%d-%d)\n", 1017 h->ip_id, cur->fe_off, cur->fe_len, off, 1018 max, fra->fe_off, fra->fe_len)); 1019 fra->fe_off = cur->fe_off; 1020 TAILQ_REMOVE(&(*frag)->fr_queue, cur, fr_next); 1021 uma_zfree(V_pf_frent_z, cur); 1022 cur = NULL; 1023 1024 } else if (frp && fra->fe_off <= frp->fe_len) { 1025 /* Need to merge in a modified 'frp' */ 1026 KASSERT((cur == NULL), ("cur != NULL: %s", 1027 __FUNCTION__)); 1028 DPFPRINTF(("fragcache[%d]: adjacent(merge " 1029 "%d-%d) %d-%d (%d-%d)\n", 1030 h->ip_id, frp->fe_off, frp->fe_len, off, 1031 max, fra->fe_off, fra->fe_len)); 1032 fra->fe_off = frp->fe_off; 1033 TAILQ_REMOVE(&(*frag)->fr_queue, frp, fr_next); 1034 uma_zfree(V_pf_frent_z, frp); 1035 frp = NULL; 1036 1037 } 1038 } 1039 } 1040 1041 if (hosed) { 1042 /* 1043 * We must keep tracking the overall fragment even when 1044 * we're going to drop it anyway so that we know when to 1045 * free the overall descriptor. Thus we drop the frag late. 1046 */ 1047 goto drop_fragment; 1048 } 1049 1050 1051 pass: 1052 /* Update maximum data size */ 1053 if ((*frag)->fr_max < max) 1054 (*frag)->fr_max = max; 1055 1056 /* This is the last segment */ 1057 if (!mff) 1058 (*frag)->fr_flags |= PFFRAG_SEENLAST; 1059 1060 /* Check if we are completely reassembled */ 1061 if (((*frag)->fr_flags & PFFRAG_SEENLAST) && 1062 TAILQ_FIRST(&(*frag)->fr_queue)->fe_off == 0 && 1063 TAILQ_FIRST(&(*frag)->fr_queue)->fe_len == (*frag)->fr_max) { 1064 /* Remove from fragment queue */ 1065 DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id, 1066 (*frag)->fr_max)); 1067 pf_free_fragment(*frag); 1068 *frag = NULL; 1069 } 1070 1071 return (m); 1072 1073 no_mem: 1074 *nomem = 1; 1075 1076 /* Still need to pay attention to !IP_MF */ 1077 if (!mff && *frag != NULL) 1078 (*frag)->fr_flags |= PFFRAG_SEENLAST; 1079 1080 m_freem(m); 1081 return (NULL); 1082 1083 drop_fragment: 1084 1085 /* Still need to pay attention to !IP_MF */ 1086 if (!mff && *frag != NULL) 1087 (*frag)->fr_flags |= PFFRAG_SEENLAST; 1088 1089 if (drop) { 1090 /* This fragment has been deemed bad. Don't reass */ 1091 if (((*frag)->fr_flags & PFFRAG_DROP) == 0) 1092 DPFPRINTF(("fragcache[%d]: dropping overall fragment\n", 1093 h->ip_id)); 1094 (*frag)->fr_flags |= PFFRAG_DROP; 1095 } 1096 1097 m_freem(m); 1098 return (NULL); 1099} 1100 1101int 1102pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag) 1103{ 1104 struct mbuf *m = *m0, *t; 1105 struct pf_fragment_tag *ftag = (struct pf_fragment_tag *)(mtag + 1); 1106 struct pf_pdesc pd; 1107 uint32_t frag_id; 1108 uint16_t hdrlen, extoff, maxlen; 1109 uint8_t proto; 1110 int error, action; 1111 1112 hdrlen = ftag->ft_hdrlen; 1113 extoff = ftag->ft_extoff; 1114 maxlen = ftag->ft_maxlen; 1115 frag_id = ftag->ft_id; 1116 m_tag_delete(m, mtag); 1117 mtag = NULL; 1118 ftag = NULL; 1119 1120 if (extoff) { 1121 int off; 1122 1123 /* Use protocol from next field of last extension header */ 1124 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt), 1125 &off); 1126 KASSERT((m != NULL), ("pf_refragment6: short mbuf chain")); 1127 proto = *(mtod(m, caddr_t) + off); 1128 *(mtod(m, char *) + off) = IPPROTO_FRAGMENT; 1129 m = *m0; 1130 } else { 1131 struct ip6_hdr *hdr; 1132 1133 hdr = mtod(m, struct ip6_hdr *); 1134 proto = hdr->ip6_nxt; 1135 hdr->ip6_nxt = IPPROTO_FRAGMENT; 1136 } 1137 1138 /* 1139 * Maxlen may be less than 8 if there was only a single 1140 * fragment. As it was fragmented before, add a fragment 1141 * header also for a single fragment. If total or maxlen 1142 * is less than 8, ip6_fragment() will return EMSGSIZE and 1143 * we drop the packet. 1144 */ 1145 error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id); 1146 m = (*m0)->m_nextpkt; 1147 (*m0)->m_nextpkt = NULL; 1148 if (error == 0) { 1149 /* The first mbuf contains the unfragmented packet. */ 1150 m_freem(*m0); 1151 *m0 = NULL; 1152 action = PF_PASS; 1153 } else { 1154 /* Drop expects an mbuf to free. */ 1155 DPFPRINTF(("refragment error %d", error)); 1156 action = PF_DROP; 1157 } 1158 for (t = m; m; m = t) { 1159 t = m->m_nextpkt; 1160 m->m_nextpkt = NULL; 1161 memset(&pd, 0, sizeof(pd)); 1162 pd.pf_mtag = pf_find_mtag(m); 1163 if (error == 0) 1164 ip6_forward(m, 0); 1165 else 1166 m_freem(m); 1167 } 1168 1169 return (action); 1170} 1171 1172int 1173pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason, 1174 struct pf_pdesc *pd) 1175{ 1176 struct mbuf *m = *m0; 1177 struct pf_rule *r; 1178 struct pf_fragment *frag = NULL; 1179 struct pf_fragment_cmp key; 1180 struct ip *h = mtod(m, struct ip *); 1181 int mff = (ntohs(h->ip_off) & IP_MF); 1182 int hlen = h->ip_hl << 2; 1183 u_int16_t fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3; 1184 u_int16_t max; 1185 int ip_len; 1186 int ip_off; 1187 int tag = -1; 1188 int verdict; 1189 1190 PF_RULES_RASSERT(); 1191 1192 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1193 while (r != NULL) { 1194 r->evaluations++; 1195 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1196 r = r->skip[PF_SKIP_IFP].ptr; 1197 else if (r->direction && r->direction != dir) 1198 r = r->skip[PF_SKIP_DIR].ptr; 1199 else if (r->af && r->af != AF_INET) 1200 r = r->skip[PF_SKIP_AF].ptr; 1201 else if (r->proto && r->proto != h->ip_p) 1202 r = r->skip[PF_SKIP_PROTO].ptr; 1203 else if (PF_MISMATCHAW(&r->src.addr, 1204 (struct pf_addr *)&h->ip_src.s_addr, AF_INET, 1205 r->src.neg, kif, M_GETFIB(m))) 1206 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1207 else if (PF_MISMATCHAW(&r->dst.addr, 1208 (struct pf_addr *)&h->ip_dst.s_addr, AF_INET, 1209 r->dst.neg, NULL, M_GETFIB(m))) 1210 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1211 else if (r->match_tag && !pf_match_tag(m, r, &tag, 1212 pd->pf_mtag ? pd->pf_mtag->tag : 0)) 1213 r = TAILQ_NEXT(r, entries); 1214 else 1215 break; 1216 } 1217 1218 if (r == NULL || r->action == PF_NOSCRUB) 1219 return (PF_PASS); 1220 else { 1221 r->packets[dir == PF_OUT]++; 1222 r->bytes[dir == PF_OUT] += pd->tot_len; 1223 } 1224 1225 /* Check for illegal packets */ 1226 if (hlen < (int)sizeof(struct ip)) 1227 goto drop; 1228 1229 if (hlen > ntohs(h->ip_len)) 1230 goto drop; 1231 1232 /* Clear IP_DF if the rule uses the no-df option */ 1233 if (r->rule_flag & PFRULE_NODF && h->ip_off & htons(IP_DF)) { 1234 u_int16_t ip_off = h->ip_off; 1235 1236 h->ip_off &= htons(~IP_DF); 1237 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1238 } 1239 1240 /* We will need other tests here */ 1241 if (!fragoff && !mff) 1242 goto no_fragment; 1243 1244 /* We're dealing with a fragment now. Don't allow fragments 1245 * with IP_DF to enter the cache. If the flag was cleared by 1246 * no-df above, fine. Otherwise drop it. 1247 */ 1248 if (h->ip_off & htons(IP_DF)) { 1249 DPFPRINTF(("IP_DF\n")); 1250 goto bad; 1251 } 1252 1253 ip_len = ntohs(h->ip_len) - hlen; 1254 ip_off = (ntohs(h->ip_off) & IP_OFFMASK) << 3; 1255 1256 /* All fragments are 8 byte aligned */ 1257 if (mff && (ip_len & 0x7)) { 1258 DPFPRINTF(("mff and %d\n", ip_len)); 1259 goto bad; 1260 } 1261 1262 /* Respect maximum length */ 1263 if (fragoff + ip_len > IP_MAXPACKET) { 1264 DPFPRINTF(("max packet %d\n", fragoff + ip_len)); 1265 goto bad; 1266 } 1267 max = fragoff + ip_len; 1268 1269 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) { 1270 1271 /* Fully buffer all of the fragments */ 1272 PF_FRAG_LOCK(); 1273 1274 pf_ip2key(h, dir, &key); 1275 frag = pf_find_fragment(&key, &V_pf_frag_tree); 1276 1277 /* Check if we saw the last fragment already */ 1278 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 1279 max > frag->fr_max) 1280 goto bad; 1281 1282 /* Might return a completely reassembled mbuf, or NULL */ 1283 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max)); 1284 verdict = pf_reassemble(m0, h, dir, reason); 1285 PF_FRAG_UNLOCK(); 1286 1287 if (verdict != PF_PASS) 1288 return (PF_DROP); 1289 1290 m = *m0; 1291 if (m == NULL) 1292 return (PF_DROP); 1293 1294 /* use mtag from concatenated mbuf chain */ 1295 pd->pf_mtag = pf_find_mtag(m); 1296#ifdef DIAGNOSTIC 1297 if (pd->pf_mtag == NULL) { 1298 printf("%s: pf_find_mtag returned NULL(1)\n", __func__); 1299 if ((pd->pf_mtag = pf_get_mtag(m)) == NULL) { 1300 m_freem(m); 1301 *m0 = NULL; 1302 goto no_mem; 1303 } 1304 } 1305#endif 1306 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP)) 1307 goto drop; 1308 1309 h = mtod(m, struct ip *); 1310 } else { 1311 /* non-buffering fragment cache (drops or masks overlaps) */ 1312 int nomem = 0; 1313 1314 if (dir == PF_OUT && pd->pf_mtag->flags & PF_TAG_FRAGCACHE) { 1315 /* 1316 * Already passed the fragment cache in the 1317 * input direction. If we continued, it would 1318 * appear to be a dup and would be dropped. 1319 */ 1320 goto fragment_pass; 1321 } 1322 1323 PF_FRAG_LOCK(); 1324 pf_ip2key(h, dir, &key); 1325 frag = pf_find_fragment(&key, &V_pf_cache_tree); 1326 1327 /* Check if we saw the last fragment already */ 1328 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) && 1329 max > frag->fr_max) { 1330 if (r->rule_flag & PFRULE_FRAGDROP) 1331 frag->fr_flags |= PFFRAG_DROP; 1332 goto bad; 1333 } 1334 1335 *m0 = m = pf_fragcache(m0, h, &frag, mff, 1336 (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem); 1337 PF_FRAG_UNLOCK(); 1338 if (m == NULL) { 1339 if (nomem) 1340 goto no_mem; 1341 goto drop; 1342 } 1343 1344 /* use mtag from copied and trimmed mbuf chain */ 1345 pd->pf_mtag = pf_find_mtag(m); 1346#ifdef DIAGNOSTIC 1347 if (pd->pf_mtag == NULL) { 1348 printf("%s: pf_find_mtag returned NULL(2)\n", __func__); 1349 if ((pd->pf_mtag = pf_get_mtag(m)) == NULL) { 1350 m_freem(m); 1351 *m0 = NULL; 1352 goto no_mem; 1353 } 1354 } 1355#endif 1356 if (dir == PF_IN) 1357 pd->pf_mtag->flags |= PF_TAG_FRAGCACHE; 1358 1359 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP)) 1360 goto drop; 1361 goto fragment_pass; 1362 } 1363 1364 no_fragment: 1365 /* At this point, only IP_DF is allowed in ip_off */ 1366 if (h->ip_off & ~htons(IP_DF)) { 1367 u_int16_t ip_off = h->ip_off; 1368 1369 h->ip_off &= htons(IP_DF); 1370 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 1371 } 1372 1373 /* not missing a return here */ 1374 1375 fragment_pass: 1376 pf_scrub_ip(&m, r->rule_flag, r->min_ttl, r->set_tos); 1377 1378 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) 1379 pd->flags |= PFDESC_IP_REAS; 1380 return (PF_PASS); 1381 1382 no_mem: 1383 REASON_SET(reason, PFRES_MEMORY); 1384 if (r != NULL && r->log) 1385 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd, 1386 1); 1387 return (PF_DROP); 1388 1389 drop: 1390 REASON_SET(reason, PFRES_NORM); 1391 if (r != NULL && r->log) 1392 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd, 1393 1); 1394 return (PF_DROP); 1395 1396 bad: 1397 DPFPRINTF(("dropping bad fragment\n")); 1398 1399 /* Free associated fragments */ 1400 if (frag != NULL) { 1401 pf_free_fragment(frag); 1402 PF_FRAG_UNLOCK(); 1403 } 1404 1405 REASON_SET(reason, PFRES_FRAG); 1406 if (r != NULL && r->log) 1407 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd, 1408 1); 1409 1410 return (PF_DROP); 1411} 1412#endif 1413 1414#ifdef INET6 1415int 1416pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif, 1417 u_short *reason, struct pf_pdesc *pd) 1418{ 1419 struct mbuf *m = *m0; 1420 struct pf_rule *r; 1421 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1422 int extoff; 1423 int off; 1424 struct ip6_ext ext; 1425 struct ip6_opt opt; 1426 struct ip6_opt_jumbo jumbo; 1427 struct ip6_frag frag; 1428 u_int32_t jumbolen = 0, plen; 1429 int optend; 1430 int ooff; 1431 u_int8_t proto; 1432 int terminal; 1433 1434 PF_RULES_RASSERT(); 1435 1436 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1437 while (r != NULL) { 1438 r->evaluations++; 1439 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1440 r = r->skip[PF_SKIP_IFP].ptr; 1441 else if (r->direction && r->direction != dir) 1442 r = r->skip[PF_SKIP_DIR].ptr; 1443 else if (r->af && r->af != AF_INET6) 1444 r = r->skip[PF_SKIP_AF].ptr; 1445#if 0 /* header chain! */ 1446 else if (r->proto && r->proto != h->ip6_nxt) 1447 r = r->skip[PF_SKIP_PROTO].ptr; 1448#endif 1449 else if (PF_MISMATCHAW(&r->src.addr, 1450 (struct pf_addr *)&h->ip6_src, AF_INET6, 1451 r->src.neg, kif, M_GETFIB(m))) 1452 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1453 else if (PF_MISMATCHAW(&r->dst.addr, 1454 (struct pf_addr *)&h->ip6_dst, AF_INET6, 1455 r->dst.neg, NULL, M_GETFIB(m))) 1456 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1457 else 1458 break; 1459 } 1460 1461 if (r == NULL || r->action == PF_NOSCRUB) 1462 return (PF_PASS); 1463 else { 1464 r->packets[dir == PF_OUT]++; 1465 r->bytes[dir == PF_OUT] += pd->tot_len; 1466 } 1467 1468 /* Check for illegal packets */ 1469 if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len) 1470 goto drop; 1471 1472 extoff = 0; 1473 off = sizeof(struct ip6_hdr); 1474 proto = h->ip6_nxt; 1475 terminal = 0; 1476 do { 1477 switch (proto) { 1478 case IPPROTO_FRAGMENT: 1479 goto fragment; 1480 break; 1481 case IPPROTO_AH: 1482 case IPPROTO_ROUTING: 1483 case IPPROTO_DSTOPTS: 1484 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1485 NULL, AF_INET6)) 1486 goto shortpkt; 1487 extoff = off; 1488 if (proto == IPPROTO_AH) 1489 off += (ext.ip6e_len + 2) * 4; 1490 else 1491 off += (ext.ip6e_len + 1) * 8; 1492 proto = ext.ip6e_nxt; 1493 break; 1494 case IPPROTO_HOPOPTS: 1495 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL, 1496 NULL, AF_INET6)) 1497 goto shortpkt; 1498 extoff = off; 1499 optend = off + (ext.ip6e_len + 1) * 8; 1500 ooff = off + sizeof(ext); 1501 do { 1502 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type, 1503 sizeof(opt.ip6o_type), NULL, NULL, 1504 AF_INET6)) 1505 goto shortpkt; 1506 if (opt.ip6o_type == IP6OPT_PAD1) { 1507 ooff++; 1508 continue; 1509 } 1510 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt), 1511 NULL, NULL, AF_INET6)) 1512 goto shortpkt; 1513 if (ooff + sizeof(opt) + opt.ip6o_len > optend) 1514 goto drop; 1515 switch (opt.ip6o_type) { 1516 case IP6OPT_JUMBO: 1517 if (h->ip6_plen != 0) 1518 goto drop; 1519 if (!pf_pull_hdr(m, ooff, &jumbo, 1520 sizeof(jumbo), NULL, NULL, 1521 AF_INET6)) 1522 goto shortpkt; 1523 memcpy(&jumbolen, jumbo.ip6oj_jumbo_len, 1524 sizeof(jumbolen)); 1525 jumbolen = ntohl(jumbolen); 1526 if (jumbolen <= IPV6_MAXPACKET) 1527 goto drop; 1528 if (sizeof(struct ip6_hdr) + jumbolen != 1529 m->m_pkthdr.len) 1530 goto drop; 1531 break; 1532 default: 1533 break; 1534 } 1535 ooff += sizeof(opt) + opt.ip6o_len; 1536 } while (ooff < optend); 1537 1538 off = optend; 1539 proto = ext.ip6e_nxt; 1540 break; 1541 default: 1542 terminal = 1; 1543 break; 1544 } 1545 } while (!terminal); 1546 1547 /* jumbo payload option must be present, or plen > 0 */ 1548 if (ntohs(h->ip6_plen) == 0) 1549 plen = jumbolen; 1550 else 1551 plen = ntohs(h->ip6_plen); 1552 if (plen == 0) 1553 goto drop; 1554 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1555 goto shortpkt; 1556 1557 pf_scrub_ip6(&m, r->min_ttl); 1558 1559 return (PF_PASS); 1560 1561 fragment: 1562 /* Jumbo payload packets cannot be fragmented. */ 1563 plen = ntohs(h->ip6_plen); 1564 if (plen == 0 || jumbolen) 1565 goto drop; 1566 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) 1567 goto shortpkt; 1568 1569 if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6)) 1570 goto shortpkt; 1571 1572 /* Offset now points to data portion. */ 1573 off += sizeof(frag); 1574 1575 /* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */ 1576 if (pf_reassemble6(m0, h, &frag, off, extoff, dir, reason) != PF_PASS) 1577 return (PF_DROP); 1578 m = *m0; 1579 if (m == NULL) 1580 return (PF_DROP); 1581 1582 pd->flags |= PFDESC_IP_REAS; 1583 return (PF_PASS); 1584 1585 shortpkt: 1586 REASON_SET(reason, PFRES_SHORT); 1587 if (r != NULL && r->log) 1588 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd, 1589 1); 1590 return (PF_DROP); 1591 1592 drop: 1593 REASON_SET(reason, PFRES_NORM); 1594 if (r != NULL && r->log) 1595 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd, 1596 1); 1597 return (PF_DROP); 1598} 1599#endif /* INET6 */ 1600 1601int 1602pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff, 1603 int off, void *h, struct pf_pdesc *pd) 1604{ 1605 struct pf_rule *r, *rm = NULL; 1606 struct tcphdr *th = pd->hdr.tcp; 1607 int rewrite = 0; 1608 u_short reason; 1609 u_int8_t flags; 1610 sa_family_t af = pd->af; 1611 1612 PF_RULES_RASSERT(); 1613 1614 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr); 1615 while (r != NULL) { 1616 r->evaluations++; 1617 if (pfi_kif_match(r->kif, kif) == r->ifnot) 1618 r = r->skip[PF_SKIP_IFP].ptr; 1619 else if (r->direction && r->direction != dir) 1620 r = r->skip[PF_SKIP_DIR].ptr; 1621 else if (r->af && r->af != af) 1622 r = r->skip[PF_SKIP_AF].ptr; 1623 else if (r->proto && r->proto != pd->proto) 1624 r = r->skip[PF_SKIP_PROTO].ptr; 1625 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, 1626 r->src.neg, kif, M_GETFIB(m))) 1627 r = r->skip[PF_SKIP_SRC_ADDR].ptr; 1628 else if (r->src.port_op && !pf_match_port(r->src.port_op, 1629 r->src.port[0], r->src.port[1], th->th_sport)) 1630 r = r->skip[PF_SKIP_SRC_PORT].ptr; 1631 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, 1632 r->dst.neg, NULL, M_GETFIB(m))) 1633 r = r->skip[PF_SKIP_DST_ADDR].ptr; 1634 else if (r->dst.port_op && !pf_match_port(r->dst.port_op, 1635 r->dst.port[0], r->dst.port[1], th->th_dport)) 1636 r = r->skip[PF_SKIP_DST_PORT].ptr; 1637 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match( 1638 pf_osfp_fingerprint(pd, m, off, th), 1639 r->os_fingerprint)) 1640 r = TAILQ_NEXT(r, entries); 1641 else { 1642 rm = r; 1643 break; 1644 } 1645 } 1646 1647 if (rm == NULL || rm->action == PF_NOSCRUB) 1648 return (PF_PASS); 1649 else { 1650 r->packets[dir == PF_OUT]++; 1651 r->bytes[dir == PF_OUT] += pd->tot_len; 1652 } 1653 1654 if (rm->rule_flag & PFRULE_REASSEMBLE_TCP) 1655 pd->flags |= PFDESC_TCP_NORM; 1656 1657 flags = th->th_flags; 1658 if (flags & TH_SYN) { 1659 /* Illegal packet */ 1660 if (flags & TH_RST) 1661 goto tcp_drop; 1662 1663 if (flags & TH_FIN) 1664 goto tcp_drop; 1665 } else { 1666 /* Illegal packet */ 1667 if (!(flags & (TH_ACK|TH_RST))) 1668 goto tcp_drop; 1669 } 1670 1671 if (!(flags & TH_ACK)) { 1672 /* These flags are only valid if ACK is set */ 1673 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG)) 1674 goto tcp_drop; 1675 } 1676 1677 /* Check for illegal header length */ 1678 if (th->th_off < (sizeof(struct tcphdr) >> 2)) 1679 goto tcp_drop; 1680 1681 /* If flags changed, or reserved data set, then adjust */ 1682 if (flags != th->th_flags || th->th_x2 != 0) { 1683 u_int16_t ov, nv; 1684 1685 ov = *(u_int16_t *)(&th->th_ack + 1); 1686 th->th_flags = flags; 1687 th->th_x2 = 0; 1688 nv = *(u_int16_t *)(&th->th_ack + 1); 1689 1690 th->th_sum = pf_cksum_fixup(th->th_sum, ov, nv, 0); 1691 rewrite = 1; 1692 } 1693 1694 /* Remove urgent pointer, if TH_URG is not set */ 1695 if (!(flags & TH_URG) && th->th_urp) { 1696 th->th_sum = pf_cksum_fixup(th->th_sum, th->th_urp, 0, 0); 1697 th->th_urp = 0; 1698 rewrite = 1; 1699 } 1700 1701 /* Process options */ 1702 if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af)) 1703 rewrite = 1; 1704 1705 /* copy back packet headers if we sanitized */ 1706 if (rewrite) 1707 m_copyback(m, off, sizeof(*th), (caddr_t)th); 1708 1709 return (PF_PASS); 1710 1711 tcp_drop: 1712 REASON_SET(&reason, PFRES_NORM); 1713 if (rm != NULL && r->log) 1714 PFLOG_PACKET(kif, m, AF_INET, dir, reason, r, NULL, NULL, pd, 1715 1); 1716 return (PF_DROP); 1717} 1718 1719int 1720pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd, 1721 struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst) 1722{ 1723 u_int32_t tsval, tsecr; 1724 u_int8_t hdr[60]; 1725 u_int8_t *opt; 1726 1727 KASSERT((src->scrub == NULL), 1728 ("pf_normalize_tcp_init: src->scrub != NULL")); 1729 1730 src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT); 1731 if (src->scrub == NULL) 1732 return (1); 1733 1734 switch (pd->af) { 1735#ifdef INET 1736 case AF_INET: { 1737 struct ip *h = mtod(m, struct ip *); 1738 src->scrub->pfss_ttl = h->ip_ttl; 1739 break; 1740 } 1741#endif /* INET */ 1742#ifdef INET6 1743 case AF_INET6: { 1744 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1745 src->scrub->pfss_ttl = h->ip6_hlim; 1746 break; 1747 } 1748#endif /* INET6 */ 1749 } 1750 1751 1752 /* 1753 * All normalizations below are only begun if we see the start of 1754 * the connections. They must all set an enabled bit in pfss_flags 1755 */ 1756 if ((th->th_flags & TH_SYN) == 0) 1757 return (0); 1758 1759 1760 if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub && 1761 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1762 /* Diddle with TCP options */ 1763 int hlen; 1764 opt = hdr + sizeof(struct tcphdr); 1765 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1766 while (hlen >= TCPOLEN_TIMESTAMP) { 1767 switch (*opt) { 1768 case TCPOPT_EOL: /* FALLTHROUGH */ 1769 case TCPOPT_NOP: 1770 opt++; 1771 hlen--; 1772 break; 1773 case TCPOPT_TIMESTAMP: 1774 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1775 src->scrub->pfss_flags |= 1776 PFSS_TIMESTAMP; 1777 src->scrub->pfss_ts_mod = 1778 htonl(arc4random()); 1779 1780 /* note PFSS_PAWS not set yet */ 1781 memcpy(&tsval, &opt[2], 1782 sizeof(u_int32_t)); 1783 memcpy(&tsecr, &opt[6], 1784 sizeof(u_int32_t)); 1785 src->scrub->pfss_tsval0 = ntohl(tsval); 1786 src->scrub->pfss_tsval = ntohl(tsval); 1787 src->scrub->pfss_tsecr = ntohl(tsecr); 1788 getmicrouptime(&src->scrub->pfss_last); 1789 } 1790 /* FALLTHROUGH */ 1791 default: 1792 hlen -= MAX(opt[1], 2); 1793 opt += MAX(opt[1], 2); 1794 break; 1795 } 1796 } 1797 } 1798 1799 return (0); 1800} 1801 1802void 1803pf_normalize_tcp_cleanup(struct pf_state *state) 1804{ 1805 if (state->src.scrub) 1806 uma_zfree(V_pf_state_scrub_z, state->src.scrub); 1807 if (state->dst.scrub) 1808 uma_zfree(V_pf_state_scrub_z, state->dst.scrub); 1809 1810 /* Someday... flush the TCP segment reassembly descriptors. */ 1811} 1812 1813int 1814pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd, 1815 u_short *reason, struct tcphdr *th, struct pf_state *state, 1816 struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback) 1817{ 1818 struct timeval uptime; 1819 u_int32_t tsval, tsecr; 1820 u_int tsval_from_last; 1821 u_int8_t hdr[60]; 1822 u_int8_t *opt; 1823 int copyback = 0; 1824 int got_ts = 0; 1825 1826 KASSERT((src->scrub || dst->scrub), 1827 ("%s: src->scrub && dst->scrub!", __func__)); 1828 1829 /* 1830 * Enforce the minimum TTL seen for this connection. Negate a common 1831 * technique to evade an intrusion detection system and confuse 1832 * firewall state code. 1833 */ 1834 switch (pd->af) { 1835#ifdef INET 1836 case AF_INET: { 1837 if (src->scrub) { 1838 struct ip *h = mtod(m, struct ip *); 1839 if (h->ip_ttl > src->scrub->pfss_ttl) 1840 src->scrub->pfss_ttl = h->ip_ttl; 1841 h->ip_ttl = src->scrub->pfss_ttl; 1842 } 1843 break; 1844 } 1845#endif /* INET */ 1846#ifdef INET6 1847 case AF_INET6: { 1848 if (src->scrub) { 1849 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 1850 if (h->ip6_hlim > src->scrub->pfss_ttl) 1851 src->scrub->pfss_ttl = h->ip6_hlim; 1852 h->ip6_hlim = src->scrub->pfss_ttl; 1853 } 1854 break; 1855 } 1856#endif /* INET6 */ 1857 } 1858 1859 if (th->th_off > (sizeof(struct tcphdr) >> 2) && 1860 ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) || 1861 (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) && 1862 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) { 1863 /* Diddle with TCP options */ 1864 int hlen; 1865 opt = hdr + sizeof(struct tcphdr); 1866 hlen = (th->th_off << 2) - sizeof(struct tcphdr); 1867 while (hlen >= TCPOLEN_TIMESTAMP) { 1868 switch (*opt) { 1869 case TCPOPT_EOL: /* FALLTHROUGH */ 1870 case TCPOPT_NOP: 1871 opt++; 1872 hlen--; 1873 break; 1874 case TCPOPT_TIMESTAMP: 1875 /* Modulate the timestamps. Can be used for 1876 * NAT detection, OS uptime determination or 1877 * reboot detection. 1878 */ 1879 1880 if (got_ts) { 1881 /* Huh? Multiple timestamps!? */ 1882 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1883 DPFPRINTF(("multiple TS??")); 1884 pf_print_state(state); 1885 printf("\n"); 1886 } 1887 REASON_SET(reason, PFRES_TS); 1888 return (PF_DROP); 1889 } 1890 if (opt[1] >= TCPOLEN_TIMESTAMP) { 1891 memcpy(&tsval, &opt[2], 1892 sizeof(u_int32_t)); 1893 if (tsval && src->scrub && 1894 (src->scrub->pfss_flags & 1895 PFSS_TIMESTAMP)) { 1896 tsval = ntohl(tsval); 1897 pf_change_a(&opt[2], 1898 &th->th_sum, 1899 htonl(tsval + 1900 src->scrub->pfss_ts_mod), 1901 0); 1902 copyback = 1; 1903 } 1904 1905 /* Modulate TS reply iff valid (!0) */ 1906 memcpy(&tsecr, &opt[6], 1907 sizeof(u_int32_t)); 1908 if (tsecr && dst->scrub && 1909 (dst->scrub->pfss_flags & 1910 PFSS_TIMESTAMP)) { 1911 tsecr = ntohl(tsecr) 1912 - dst->scrub->pfss_ts_mod; 1913 pf_change_a(&opt[6], 1914 &th->th_sum, htonl(tsecr), 1915 0); 1916 copyback = 1; 1917 } 1918 got_ts = 1; 1919 } 1920 /* FALLTHROUGH */ 1921 default: 1922 hlen -= MAX(opt[1], 2); 1923 opt += MAX(opt[1], 2); 1924 break; 1925 } 1926 } 1927 if (copyback) { 1928 /* Copyback the options, caller copys back header */ 1929 *writeback = 1; 1930 m_copyback(m, off + sizeof(struct tcphdr), 1931 (th->th_off << 2) - sizeof(struct tcphdr), hdr + 1932 sizeof(struct tcphdr)); 1933 } 1934 } 1935 1936 1937 /* 1938 * Must invalidate PAWS checks on connections idle for too long. 1939 * The fastest allowed timestamp clock is 1ms. That turns out to 1940 * be about 24 days before it wraps. XXX Right now our lowerbound 1941 * TS echo check only works for the first 12 days of a connection 1942 * when the TS has exhausted half its 32bit space 1943 */ 1944#define TS_MAX_IDLE (24*24*60*60) 1945#define TS_MAX_CONN (12*24*60*60) /* XXX remove when better tsecr check */ 1946 1947 getmicrouptime(&uptime); 1948 if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) && 1949 (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE || 1950 time_uptime - state->creation > TS_MAX_CONN)) { 1951 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1952 DPFPRINTF(("src idled out of PAWS\n")); 1953 pf_print_state(state); 1954 printf("\n"); 1955 } 1956 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS) 1957 | PFSS_PAWS_IDLED; 1958 } 1959 if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) && 1960 uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) { 1961 if (V_pf_status.debug >= PF_DEBUG_MISC) { 1962 DPFPRINTF(("dst idled out of PAWS\n")); 1963 pf_print_state(state); 1964 printf("\n"); 1965 } 1966 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS) 1967 | PFSS_PAWS_IDLED; 1968 } 1969 1970 if (got_ts && src->scrub && dst->scrub && 1971 (src->scrub->pfss_flags & PFSS_PAWS) && 1972 (dst->scrub->pfss_flags & PFSS_PAWS)) { 1973 /* Validate that the timestamps are "in-window". 1974 * RFC1323 describes TCP Timestamp options that allow 1975 * measurement of RTT (round trip time) and PAWS 1976 * (protection against wrapped sequence numbers). PAWS 1977 * gives us a set of rules for rejecting packets on 1978 * long fat pipes (packets that were somehow delayed 1979 * in transit longer than the time it took to send the 1980 * full TCP sequence space of 4Gb). We can use these 1981 * rules and infer a few others that will let us treat 1982 * the 32bit timestamp and the 32bit echoed timestamp 1983 * as sequence numbers to prevent a blind attacker from 1984 * inserting packets into a connection. 1985 * 1986 * RFC1323 tells us: 1987 * - The timestamp on this packet must be greater than 1988 * or equal to the last value echoed by the other 1989 * endpoint. The RFC says those will be discarded 1990 * since it is a dup that has already been acked. 1991 * This gives us a lowerbound on the timestamp. 1992 * timestamp >= other last echoed timestamp 1993 * - The timestamp will be less than or equal to 1994 * the last timestamp plus the time between the 1995 * last packet and now. The RFC defines the max 1996 * clock rate as 1ms. We will allow clocks to be 1997 * up to 10% fast and will allow a total difference 1998 * or 30 seconds due to a route change. And this 1999 * gives us an upperbound on the timestamp. 2000 * timestamp <= last timestamp + max ticks 2001 * We have to be careful here. Windows will send an 2002 * initial timestamp of zero and then initialize it 2003 * to a random value after the 3whs; presumably to 2004 * avoid a DoS by having to call an expensive RNG 2005 * during a SYN flood. Proof MS has at least one 2006 * good security geek. 2007 * 2008 * - The TCP timestamp option must also echo the other 2009 * endpoints timestamp. The timestamp echoed is the 2010 * one carried on the earliest unacknowledged segment 2011 * on the left edge of the sequence window. The RFC 2012 * states that the host will reject any echoed 2013 * timestamps that were larger than any ever sent. 2014 * This gives us an upperbound on the TS echo. 2015 * tescr <= largest_tsval 2016 * - The lowerbound on the TS echo is a little more 2017 * tricky to determine. The other endpoint's echoed 2018 * values will not decrease. But there may be 2019 * network conditions that re-order packets and 2020 * cause our view of them to decrease. For now the 2021 * only lowerbound we can safely determine is that 2022 * the TS echo will never be less than the original 2023 * TS. XXX There is probably a better lowerbound. 2024 * Remove TS_MAX_CONN with better lowerbound check. 2025 * tescr >= other original TS 2026 * 2027 * It is also important to note that the fastest 2028 * timestamp clock of 1ms will wrap its 32bit space in 2029 * 24 days. So we just disable TS checking after 24 2030 * days of idle time. We actually must use a 12d 2031 * connection limit until we can come up with a better 2032 * lowerbound to the TS echo check. 2033 */ 2034 struct timeval delta_ts; 2035 int ts_fudge; 2036 2037 2038 /* 2039 * PFTM_TS_DIFF is how many seconds of leeway to allow 2040 * a host's timestamp. This can happen if the previous 2041 * packet got delayed in transit for much longer than 2042 * this packet. 2043 */ 2044 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0) 2045 ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF]; 2046 2047 /* Calculate max ticks since the last timestamp */ 2048#define TS_MAXFREQ 1100 /* RFC max TS freq of 1Khz + 10% skew */ 2049#define TS_MICROSECS 1000000 /* microseconds per second */ 2050 delta_ts = uptime; 2051 timevalsub(&delta_ts, &src->scrub->pfss_last); 2052 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ; 2053 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ); 2054 2055 if ((src->state >= TCPS_ESTABLISHED && 2056 dst->state >= TCPS_ESTABLISHED) && 2057 (SEQ_LT(tsval, dst->scrub->pfss_tsecr) || 2058 SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) || 2059 (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) || 2060 SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) { 2061 /* Bad RFC1323 implementation or an insertion attack. 2062 * 2063 * - Solaris 2.6 and 2.7 are known to send another ACK 2064 * after the FIN,FIN|ACK,ACK closing that carries 2065 * an old timestamp. 2066 */ 2067 2068 DPFPRINTF(("Timestamp failed %c%c%c%c\n", 2069 SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ', 2070 SEQ_GT(tsval, src->scrub->pfss_tsval + 2071 tsval_from_last) ? '1' : ' ', 2072 SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ', 2073 SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' ')); 2074 DPFPRINTF((" tsval: %u tsecr: %u +ticks: %u " 2075 "idle: %jus %lums\n", 2076 tsval, tsecr, tsval_from_last, 2077 (uintmax_t)delta_ts.tv_sec, 2078 delta_ts.tv_usec / 1000)); 2079 DPFPRINTF((" src->tsval: %u tsecr: %u\n", 2080 src->scrub->pfss_tsval, src->scrub->pfss_tsecr)); 2081 DPFPRINTF((" dst->tsval: %u tsecr: %u tsval0: %u" 2082 "\n", dst->scrub->pfss_tsval, 2083 dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0)); 2084 if (V_pf_status.debug >= PF_DEBUG_MISC) { 2085 pf_print_state(state); 2086 pf_print_flags(th->th_flags); 2087 printf("\n"); 2088 } 2089 REASON_SET(reason, PFRES_TS); 2090 return (PF_DROP); 2091 } 2092 2093 /* XXX I'd really like to require tsecr but it's optional */ 2094 2095 } else if (!got_ts && (th->th_flags & TH_RST) == 0 && 2096 ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED) 2097 || pd->p_len > 0 || (th->th_flags & TH_SYN)) && 2098 src->scrub && dst->scrub && 2099 (src->scrub->pfss_flags & PFSS_PAWS) && 2100 (dst->scrub->pfss_flags & PFSS_PAWS)) { 2101 /* Didn't send a timestamp. Timestamps aren't really useful 2102 * when: 2103 * - connection opening or closing (often not even sent). 2104 * but we must not let an attacker to put a FIN on a 2105 * data packet to sneak it through our ESTABLISHED check. 2106 * - on a TCP reset. RFC suggests not even looking at TS. 2107 * - on an empty ACK. The TS will not be echoed so it will 2108 * probably not help keep the RTT calculation in sync and 2109 * there isn't as much danger when the sequence numbers 2110 * got wrapped. So some stacks don't include TS on empty 2111 * ACKs :-( 2112 * 2113 * To minimize the disruption to mostly RFC1323 conformant 2114 * stacks, we will only require timestamps on data packets. 2115 * 2116 * And what do ya know, we cannot require timestamps on data 2117 * packets. There appear to be devices that do legitimate 2118 * TCP connection hijacking. There are HTTP devices that allow 2119 * a 3whs (with timestamps) and then buffer the HTTP request. 2120 * If the intermediate device has the HTTP response cache, it 2121 * will spoof the response but not bother timestamping its 2122 * packets. So we can look for the presence of a timestamp in 2123 * the first data packet and if there, require it in all future 2124 * packets. 2125 */ 2126 2127 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) { 2128 /* 2129 * Hey! Someone tried to sneak a packet in. Or the 2130 * stack changed its RFC1323 behavior?!?! 2131 */ 2132 if (V_pf_status.debug >= PF_DEBUG_MISC) { 2133 DPFPRINTF(("Did not receive expected RFC1323 " 2134 "timestamp\n")); 2135 pf_print_state(state); 2136 pf_print_flags(th->th_flags); 2137 printf("\n"); 2138 } 2139 REASON_SET(reason, PFRES_TS); 2140 return (PF_DROP); 2141 } 2142 } 2143 2144 2145 /* 2146 * We will note if a host sends his data packets with or without 2147 * timestamps. And require all data packets to contain a timestamp 2148 * if the first does. PAWS implicitly requires that all data packets be 2149 * timestamped. But I think there are middle-man devices that hijack 2150 * TCP streams immediately after the 3whs and don't timestamp their 2151 * packets (seen in a WWW accelerator or cache). 2152 */ 2153 if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags & 2154 (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) { 2155 if (got_ts) 2156 src->scrub->pfss_flags |= PFSS_DATA_TS; 2157 else { 2158 src->scrub->pfss_flags |= PFSS_DATA_NOTS; 2159 if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub && 2160 (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) { 2161 /* Don't warn if other host rejected RFC1323 */ 2162 DPFPRINTF(("Broken RFC1323 stack did not " 2163 "timestamp data packet. Disabled PAWS " 2164 "security.\n")); 2165 pf_print_state(state); 2166 pf_print_flags(th->th_flags); 2167 printf("\n"); 2168 } 2169 } 2170 } 2171 2172 2173 /* 2174 * Update PAWS values 2175 */ 2176 if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags & 2177 (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) { 2178 getmicrouptime(&src->scrub->pfss_last); 2179 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) || 2180 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 2181 src->scrub->pfss_tsval = tsval; 2182 2183 if (tsecr) { 2184 if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) || 2185 (src->scrub->pfss_flags & PFSS_PAWS) == 0) 2186 src->scrub->pfss_tsecr = tsecr; 2187 2188 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 && 2189 (SEQ_LT(tsval, src->scrub->pfss_tsval0) || 2190 src->scrub->pfss_tsval0 == 0)) { 2191 /* tsval0 MUST be the lowest timestamp */ 2192 src->scrub->pfss_tsval0 = tsval; 2193 } 2194 2195 /* Only fully initialized after a TS gets echoed */ 2196 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0) 2197 src->scrub->pfss_flags |= PFSS_PAWS; 2198 } 2199 } 2200 2201 /* I have a dream.... TCP segment reassembly.... */ 2202 return (0); 2203} 2204 2205static int 2206pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th, 2207 int off, sa_family_t af) 2208{ 2209 u_int16_t *mss; 2210 int thoff; 2211 int opt, cnt, optlen = 0; 2212 int rewrite = 0; 2213 u_char opts[TCP_MAXOLEN]; 2214 u_char *optp = opts; 2215 2216 thoff = th->th_off << 2; 2217 cnt = thoff - sizeof(struct tcphdr); 2218 2219 if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt, 2220 NULL, NULL, af)) 2221 return (rewrite); 2222 2223 for (; cnt > 0; cnt -= optlen, optp += optlen) { 2224 opt = optp[0]; 2225 if (opt == TCPOPT_EOL) 2226 break; 2227 if (opt == TCPOPT_NOP) 2228 optlen = 1; 2229 else { 2230 if (cnt < 2) 2231 break; 2232 optlen = optp[1]; 2233 if (optlen < 2 || optlen > cnt) 2234 break; 2235 } 2236 switch (opt) { 2237 case TCPOPT_MAXSEG: 2238 mss = (u_int16_t *)(optp + 2); 2239 if ((ntohs(*mss)) > r->max_mss) { 2240 th->th_sum = pf_cksum_fixup(th->th_sum, 2241 *mss, htons(r->max_mss), 0); 2242 *mss = htons(r->max_mss); 2243 rewrite = 1; 2244 } 2245 break; 2246 default: 2247 break; 2248 } 2249 } 2250 2251 if (rewrite) 2252 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts); 2253 2254 return (rewrite); 2255} 2256 2257#ifdef INET 2258static void 2259pf_scrub_ip(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos) 2260{ 2261 struct mbuf *m = *m0; 2262 struct ip *h = mtod(m, struct ip *); 2263 2264 /* Clear IP_DF if no-df was requested */ 2265 if (flags & PFRULE_NODF && h->ip_off & htons(IP_DF)) { 2266 u_int16_t ip_off = h->ip_off; 2267 2268 h->ip_off &= htons(~IP_DF); 2269 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0); 2270 } 2271 2272 /* Enforce a minimum ttl, may cause endless packet loops */ 2273 if (min_ttl && h->ip_ttl < min_ttl) { 2274 u_int16_t ip_ttl = h->ip_ttl; 2275 2276 h->ip_ttl = min_ttl; 2277 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0); 2278 } 2279 2280 /* Enforce tos */ 2281 if (flags & PFRULE_SET_TOS) { 2282 u_int16_t ov, nv; 2283 2284 ov = *(u_int16_t *)h; 2285 h->ip_tos = tos; 2286 nv = *(u_int16_t *)h; 2287 2288 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0); 2289 } 2290 2291 /* random-id, but not for fragments */ 2292 if (flags & PFRULE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) { 2293 u_int16_t ip_id = h->ip_id; 2294 2295 h->ip_id = ip_randomid(); 2296 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0); 2297 } 2298} 2299#endif /* INET */ 2300 2301#ifdef INET6 2302static void 2303pf_scrub_ip6(struct mbuf **m0, u_int8_t min_ttl) 2304{ 2305 struct mbuf *m = *m0; 2306 struct ip6_hdr *h = mtod(m, struct ip6_hdr *); 2307 2308 /* Enforce a minimum ttl, may cause endless packet loops */ 2309 if (min_ttl && h->ip6_hlim < min_ttl) 2310 h->ip6_hlim = min_ttl; 2311} 2312#endif 2313