sys/netpfil/pf/pf_norm.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause
   3  *
   4  * Copyright 2001 Niels Provos <provos@citi.umich.edu>
   5  * Copyright 2011-2018 Alexander Bluhm <bluhm@openbsd.org>
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  *
  28  *      $OpenBSD: pf_norm.c,v 1.114 2009/01/29 14:11:45 henning Exp $
  29  */
  30
  31 #include <sys/cdefs.h>
  32 __FBSDID("$FreeBSD$");
  33
  34 #include "opt_inet.h"
  35 #include "opt_inet6.h"
  36 #include "opt_pf.h"
  37
  38 #include <sys/param.h>
  39 #include <sys/kernel.h>
  40 #include <sys/lock.h>
  41 #include <sys/mbuf.h>
  42 #include <sys/mutex.h>
  43 #include <sys/refcount.h>
  44 #include <sys/socket.h>
  45
  46 #include <net/if.h>
  47 #include <net/vnet.h>
  48 #include <net/pfvar.h>
  49 #include <net/if_pflog.h>
  50
  51 #include <netinet/in.h>
  52 #include <netinet/ip.h>
  53 #include <netinet/ip_var.h>
  54 #include <netinet6/ip6_var.h>
  55 #include <netinet6/scope6_var.h>
  56 #include <netinet/tcp.h>
  57 #include <netinet/tcp_fsm.h>
  58 #include <netinet/tcp_seq.h>
  59 #include <netinet/sctp_constants.h>
  60 #include <netinet/sctp_header.h>
  61
  62 #ifdef INET6
  63 #include <netinet/ip6.h>
  64 #endif /* INET6 */
  65
  66 struct pf_frent {
  67         TAILQ_ENTRY(pf_frent)   fr_next;
  68         struct mbuf     *fe_m;
  69         uint16_t        fe_hdrlen;      /* ipv4 header length with ip options
  70                                            ipv6, extension, fragment header */
  71         uint16_t        fe_extoff;      /* last extension header offset or 0 */
  72         uint16_t        fe_len;         /* fragment length */
  73         uint16_t        fe_off;         /* fragment offset */
  74         uint16_t        fe_mff;         /* more fragment flag */
  75 };
  76
  77 struct pf_fragment_cmp {
  78         struct pf_addr  frc_src;
  79         struct pf_addr  frc_dst;
  80         uint32_t        frc_id;
  81         sa_family_t     frc_af;
  82         uint8_t         frc_proto;
  83 };
  84
  85 struct pf_fragment {
  86         struct pf_fragment_cmp  fr_key;
  87 #define fr_src  fr_key.frc_src
  88 #define fr_dst  fr_key.frc_dst
  89 #define fr_id   fr_key.frc_id
  90 #define fr_af   fr_key.frc_af
  91 #define fr_proto        fr_key.frc_proto
  92
  93         /* pointers to queue element */
  94         struct pf_frent *fr_firstoff[PF_FRAG_ENTRY_POINTS];
  95         /* count entries between pointers */
  96         uint8_t fr_entries[PF_FRAG_ENTRY_POINTS];
  97         RB_ENTRY(pf_fragment) fr_entry;
  98         TAILQ_ENTRY(pf_fragment) frag_next;
  99         uint32_t        fr_timeout;
 100         uint16_t        fr_maxlen;      /* maximum length of single fragment */
 101         u_int16_t       fr_holes;       /* number of holes in the queue */
 102         TAILQ_HEAD(pf_fragq, pf_frent) fr_queue;
 103 };
 104
 105 struct pf_fragment_tag {
 106         uint16_t        ft_hdrlen;      /* header length of reassembled pkt */
 107         uint16_t        ft_extoff;      /* last extension header offset or 0 */
 108         uint16_t        ft_maxlen;      /* maximum fragment payload length */
 109         uint32_t        ft_id;          /* fragment id */
 110 };
 111
 112 VNET_DEFINE_STATIC(struct mtx, pf_frag_mtx);
 113 #define V_pf_frag_mtx           VNET(pf_frag_mtx)
 114 #define PF_FRAG_LOCK()          mtx_lock(&V_pf_frag_mtx)
 115 #define PF_FRAG_UNLOCK()        mtx_unlock(&V_pf_frag_mtx)
 116 #define PF_FRAG_ASSERT()        mtx_assert(&V_pf_frag_mtx, MA_OWNED)
 117
 118 VNET_DEFINE(uma_zone_t, pf_state_scrub_z);      /* XXX: shared with pfsync */
 119
 120 VNET_DEFINE_STATIC(uma_zone_t, pf_frent_z);
 121 #define V_pf_frent_z    VNET(pf_frent_z)
 122 VNET_DEFINE_STATIC(uma_zone_t, pf_frag_z);
 123 #define V_pf_frag_z     VNET(pf_frag_z)
 124
 125 TAILQ_HEAD(pf_fragqueue, pf_fragment);
 126 TAILQ_HEAD(pf_cachequeue, pf_fragment);
 127 VNET_DEFINE_STATIC(struct pf_fragqueue, pf_fragqueue);
 128 #define V_pf_fragqueue                  VNET(pf_fragqueue)
 129 RB_HEAD(pf_frag_tree, pf_fragment);
 130 VNET_DEFINE_STATIC(struct pf_frag_tree, pf_frag_tree);
 131 #define V_pf_frag_tree                  VNET(pf_frag_tree)
 132 static int               pf_frag_compare(struct pf_fragment *,
 133                             struct pf_fragment *);
 134 static RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 135 static RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 136
 137 static void     pf_flush_fragments(void);
 138 static void     pf_free_fragment(struct pf_fragment *);
 139 static void     pf_remove_fragment(struct pf_fragment *);
 140
 141 static struct pf_frent *pf_create_fragment(u_short *);
 142 static int      pf_frent_holes(struct pf_frent *frent);
 143 static struct pf_fragment *pf_find_fragment(struct pf_fragment_cmp *key,
 144                     struct pf_frag_tree *tree);
 145 static inline int       pf_frent_index(struct pf_frent *);
 146 static int      pf_frent_insert(struct pf_fragment *,
 147                             struct pf_frent *, struct pf_frent *);
 148 void                    pf_frent_remove(struct pf_fragment *,
 149                             struct pf_frent *);
 150 struct pf_frent         *pf_frent_previous(struct pf_fragment *,
 151                             struct pf_frent *);
 152 static struct pf_fragment *pf_fillup_fragment(struct pf_fragment_cmp *,
 153                     struct pf_frent *, u_short *);
 154 static struct mbuf *pf_join_fragment(struct pf_fragment *);
 155 #ifdef INET
 156 static int      pf_reassemble(struct mbuf **, struct ip *, int, u_short *);
 157 #endif  /* INET */
 158 #ifdef INET6
 159 static int      pf_reassemble6(struct mbuf **, struct ip6_hdr *,
 160                     struct ip6_frag *, uint16_t, uint16_t, u_short *);
 161 #endif  /* INET6 */
 162
 163 #define DPFPRINTF(x) do {                               \
 164         if (V_pf_status.debug >= PF_DEBUG_MISC) {       \
 165                 printf("%s: ", __func__);               \
 166                 printf x ;                              \
 167         }                                               \
 168 } while(0)
 169
 170 #ifdef INET
 171 static void
 172 pf_ip2key(struct ip *ip, int dir, struct pf_fragment_cmp *key)
 173 {
 174
 175         key->frc_src.v4 = ip->ip_src;
 176         key->frc_dst.v4 = ip->ip_dst;
 177         key->frc_af = AF_INET;
 178         key->frc_proto = ip->ip_p;
 179         key->frc_id = ip->ip_id;
 180 }
 181 #endif  /* INET */
 182
 183 void
 184 pf_normalize_init(void)
 185 {
 186
 187         V_pf_frag_z = uma_zcreate("pf frags", sizeof(struct pf_fragment),
 188             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 189         V_pf_frent_z = uma_zcreate("pf frag entries", sizeof(struct pf_frent),
 190             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 191         V_pf_state_scrub_z = uma_zcreate("pf state scrubs",
 192             sizeof(struct pf_state_scrub),  NULL, NULL, NULL, NULL,
 193             UMA_ALIGN_PTR, 0);
 194
 195         mtx_init(&V_pf_frag_mtx, "pf fragments", NULL, MTX_DEF);
 196
 197         V_pf_limits[PF_LIMIT_FRAGS].zone = V_pf_frent_z;
 198         V_pf_limits[PF_LIMIT_FRAGS].limit = PFFRAG_FRENT_HIWAT;
 199         uma_zone_set_max(V_pf_frent_z, PFFRAG_FRENT_HIWAT);
 200         uma_zone_set_warning(V_pf_frent_z, "PF frag entries limit reached");
 201
 202         TAILQ_INIT(&V_pf_fragqueue);
 203 }
 204
 205 void
 206 pf_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(&V_pf_frag_mtx);
 214 }
 215
 216 static int
 217 pf_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
 234 void
 235 pf_purge_expired_fragments(void)
 236 {
 237         u_int32_t       expire = time_uptime -
 238                             V_pf_default_rule.timeout[PFTM_FRAG];
 239
 240         pf_purge_fragments(expire);
 241 }
 242
 243 void
 244 pf_purge_fragments(uint32_t expire)
 245 {
 246         struct pf_fragment      *frag;
 247
 248         PF_FRAG_LOCK();
 249         while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) {
 250                 if (frag->fr_timeout > expire)
 251                         break;
 252
 253                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 254                 pf_free_fragment(frag);
 255         }
 256
 257         PF_FRAG_UNLOCK();
 258 }
 259
 260 /*
 261  * Try to flush old fragments to make space for new ones
 262  */
 263 static void
 264 pf_flush_fragments(void)
 265 {
 266         struct pf_fragment      *frag;
 267         int                      goal;
 268
 269         PF_FRAG_ASSERT();
 270
 271         goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10;
 272         DPFPRINTF(("trying to free %d frag entriess\n", goal));
 273         while (goal < uma_zone_get_cur(V_pf_frent_z)) {
 274                 frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue);
 275                 if (frag)
 276                         pf_free_fragment(frag);
 277                 else
 278                         break;
 279         }
 280 }
 281
 282 /* Frees the fragments and all associated entries */
 283 static void
 284 pf_free_fragment(struct pf_fragment *frag)
 285 {
 286         struct pf_frent         *frent;
 287
 288         PF_FRAG_ASSERT();
 289
 290         /* Free all fragments */
 291         for (frent = TAILQ_FIRST(&frag->fr_queue); frent;
 292             frent = TAILQ_FIRST(&frag->fr_queue)) {
 293                 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
 294
 295                 m_freem(frent->fe_m);
 296                 uma_zfree(V_pf_frent_z, frent);
 297         }
 298
 299         pf_remove_fragment(frag);
 300 }
 301
 302 static struct pf_fragment *
 303 pf_find_fragment(struct pf_fragment_cmp *key, struct pf_frag_tree *tree)
 304 {
 305         struct pf_fragment      *frag;
 306
 307         PF_FRAG_ASSERT();
 308
 309         frag = RB_FIND(pf_frag_tree, tree, (struct pf_fragment *)key);
 310         if (frag != NULL) {
 311                 /* XXX Are we sure we want to update the timeout? */
 312                 frag->fr_timeout = time_uptime;
 313                 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 314                 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
 315         }
 316
 317         return (frag);
 318 }
 319
 320 /* Removes a fragment from the fragment queue and frees the fragment */
 321 static void
 322 pf_remove_fragment(struct pf_fragment *frag)
 323 {
 324
 325         PF_FRAG_ASSERT();
 326         KASSERT(frag, ("frag != NULL"));
 327
 328         RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag);
 329         TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 330         uma_zfree(V_pf_frag_z, frag);
 331 }
 332
 333 static struct pf_frent *
 334 pf_create_fragment(u_short *reason)
 335 {
 336         struct pf_frent *frent;
 337
 338         PF_FRAG_ASSERT();
 339
 340         frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 341         if (frent == NULL) {
 342                 pf_flush_fragments();
 343                 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 344                 if (frent == NULL) {
 345                         REASON_SET(reason, PFRES_MEMORY);
 346                         return (NULL);
 347                 }
 348         }
 349
 350         return (frent);
 351 }
 352
 353 /*
 354  * Calculate the additional holes that were created in the fragment
 355  * queue by inserting this fragment.  A fragment in the middle
 356  * creates one more hole by splitting.  For each connected side,
 357  * it loses one hole.
 358  * Fragment entry must be in the queue when calling this function.
 359  */
 360 static int
 361 pf_frent_holes(struct pf_frent *frent)
 362 {
 363         struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next);
 364         struct pf_frent *next = TAILQ_NEXT(frent, fr_next);
 365         int holes = 1;
 366
 367         if (prev == NULL) {
 368                 if (frent->fe_off == 0)
 369                         holes--;
 370         } else {
 371                 KASSERT(frent->fe_off != 0, ("frent->fe_off != 0"));
 372                 if (frent->fe_off == prev->fe_off + prev->fe_len)
 373                         holes--;
 374         }
 375         if (next == NULL) {
 376                 if (!frent->fe_mff)
 377                         holes--;
 378         } else {
 379                 KASSERT(frent->fe_mff, ("frent->fe_mff"));
 380                 if (next->fe_off == frent->fe_off + frent->fe_len)
 381                         holes--;
 382         }
 383         return holes;
 384 }
 385
 386 static inline int
 387 pf_frent_index(struct pf_frent *frent)
 388 {
 389         /*
 390          * We have an array of 16 entry points to the queue.  A full size
 391          * 65535 octet IP packet can have 8192 fragments.  So the queue
 392          * traversal length is at most 512 and at most 16 entry points are
 393          * checked.  We need 128 additional bytes on a 64 bit architecture.
 394          */
 395         CTASSERT(((u_int16_t)0xffff &~ 7) / (0x10000 / PF_FRAG_ENTRY_POINTS) ==
 396             16 - 1);
 397         CTASSERT(((u_int16_t)0xffff >> 3) / PF_FRAG_ENTRY_POINTS == 512 - 1);
 398
 399         return frent->fe_off / (0x10000 / PF_FRAG_ENTRY_POINTS);
 400 }
 401
 402 static int
 403 pf_frent_insert(struct pf_fragment *frag, struct pf_frent *frent,
 404     struct pf_frent *prev)
 405 {
 406         int index;
 407
 408         CTASSERT(PF_FRAG_ENTRY_LIMIT <= 0xff);
 409
 410         /*
 411          * A packet has at most 65536 octets.  With 16 entry points, each one
 412          * spawns 4096 octets.  We limit these to 64 fragments each, which
 413          * means on average every fragment must have at least 64 octets.
 414          */
 415         index = pf_frent_index(frent);
 416         if (frag->fr_entries[index] >= PF_FRAG_ENTRY_LIMIT)
 417                 return ENOBUFS;
 418         frag->fr_entries[index]++;
 419
 420         if (prev == NULL) {
 421                 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next);
 422         } else {
 423                 KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off,
 424                     ("overlapping fragment"));
 425                 TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next);
 426         }
 427
 428         if (frag->fr_firstoff[index] == NULL) {
 429                 KASSERT(prev == NULL || pf_frent_index(prev) < index,
 430                     ("prev == NULL || pf_frent_index(pref) < index"));
 431                 frag->fr_firstoff[index] = frent;
 432         } else {
 433                 if (frent->fe_off < frag->fr_firstoff[index]->fe_off) {
 434                         KASSERT(prev == NULL || pf_frent_index(prev) < index,
 435                             ("prev == NULL || pf_frent_index(pref) < index"));
 436                         frag->fr_firstoff[index] = frent;
 437                 } else {
 438                         KASSERT(prev != NULL, ("prev != NULL"));
 439                         KASSERT(pf_frent_index(prev) == index,
 440                             ("pf_frent_index(prev) == index"));
 441                 }
 442         }
 443
 444         frag->fr_holes += pf_frent_holes(frent);
 445
 446         return 0;
 447 }
 448
 449 void
 450 pf_frent_remove(struct pf_fragment *frag, struct pf_frent *frent)
 451 {
 452 #ifdef INVARIANTS
 453         struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next);
 454 #endif
 455         struct pf_frent *next = TAILQ_NEXT(frent, fr_next);
 456         int index;
 457
 458         frag->fr_holes -= pf_frent_holes(frent);
 459
 460         index = pf_frent_index(frent);
 461         KASSERT(frag->fr_firstoff[index] != NULL, ("frent not found"));
 462         if (frag->fr_firstoff[index]->fe_off == frent->fe_off) {
 463                 if (next == NULL) {
 464                         frag->fr_firstoff[index] = NULL;
 465                 } else {
 466                         KASSERT(frent->fe_off + frent->fe_len <= next->fe_off,
 467                             ("overlapping fragment"));
 468                         if (pf_frent_index(next) == index) {
 469                                 frag->fr_firstoff[index] = next;
 470                         } else {
 471                                 frag->fr_firstoff[index] = NULL;
 472                         }
 473                 }
 474         } else {
 475                 KASSERT(frag->fr_firstoff[index]->fe_off < frent->fe_off,
 476                     ("frag->fr_firstoff[index]->fe_off < frent->fe_off"));
 477                 KASSERT(prev != NULL, ("prev != NULL"));
 478                 KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off,
 479                     ("overlapping fragment"));
 480                 KASSERT(pf_frent_index(prev) == index,
 481                     ("pf_frent_index(prev) == index"));
 482         }
 483
 484         TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
 485
 486         KASSERT(frag->fr_entries[index] > 0, ("No fragments remaining"));
 487         frag->fr_entries[index]--;
 488 }
 489
 490 struct pf_frent *
 491 pf_frent_previous(struct pf_fragment *frag, struct pf_frent *frent)
 492 {
 493         struct pf_frent *prev, *next;
 494         int index;
 495
 496         /*
 497          * If there are no fragments after frag, take the final one.  Assume
 498          * that the global queue is not empty.
 499          */
 500         prev = TAILQ_LAST(&frag->fr_queue, pf_fragq);
 501         KASSERT(prev != NULL, ("prev != NULL"));
 502         if (prev->fe_off <= frent->fe_off)
 503                 return prev;
 504         /*
 505          * We want to find a fragment entry that is before frag, but still
 506          * close to it.  Find the first fragment entry that is in the same
 507          * entry point or in the first entry point after that.  As we have
 508          * already checked that there are entries behind frag, this will
 509          * succeed.
 510          */
 511         for (index = pf_frent_index(frent); index < PF_FRAG_ENTRY_POINTS;
 512             index++) {
 513                 prev = frag->fr_firstoff[index];
 514                 if (prev != NULL)
 515                         break;
 516         }
 517         KASSERT(prev != NULL, ("prev != NULL"));
 518         /*
 519          * In prev we may have a fragment from the same entry point that is
 520          * before frent, or one that is just one position behind frent.
 521          * In the latter case, we go back one step and have the predecessor.
 522          * There may be none if the new fragment will be the first one.
 523          */
 524         if (prev->fe_off > frent->fe_off) {
 525                 prev = TAILQ_PREV(prev, pf_fragq, fr_next);
 526                 if (prev == NULL)
 527                         return NULL;
 528                 KASSERT(prev->fe_off <= frent->fe_off,
 529                     ("prev->fe_off <= frent->fe_off"));
 530                 return prev;
 531         }
 532         /*
 533          * In prev is the first fragment of the entry point.  The offset
 534          * of frag is behind it.  Find the closest previous fragment.
 535          */
 536         for (next = TAILQ_NEXT(prev, fr_next); next != NULL;
 537             next = TAILQ_NEXT(next, fr_next)) {
 538                 if (next->fe_off > frent->fe_off)
 539                         break;
 540                 prev = next;
 541         }
 542         return prev;
 543 }
 544
 545 static struct pf_fragment *
 546 pf_fillup_fragment(struct pf_fragment_cmp *key, struct pf_frent *frent,
 547     u_short *reason)
 548 {
 549         struct pf_frent         *after, *next, *prev;
 550         struct pf_fragment      *frag;
 551         uint16_t                total;
 552         int                     old_index, new_index;
 553
 554         PF_FRAG_ASSERT();
 555
 556         /* No empty fragments. */
 557         if (frent->fe_len == 0) {
 558                 DPFPRINTF(("bad fragment: len 0\n"));
 559                 goto bad_fragment;
 560         }
 561
 562         /* All fragments are 8 byte aligned. */
 563         if (frent->fe_mff && (frent->fe_len & 0x7)) {
 564                 DPFPRINTF(("bad fragment: mff and len %d\n", frent->fe_len));
 565                 goto bad_fragment;
 566         }
 567
 568         /* Respect maximum length, IP_MAXPACKET == IPV6_MAXPACKET. */
 569         if (frent->fe_off + frent->fe_len > IP_MAXPACKET) {
 570                 DPFPRINTF(("bad fragment: max packet %d\n",
 571                     frent->fe_off + frent->fe_len));
 572                 goto bad_fragment;
 573         }
 574
 575         DPFPRINTF((key->frc_af == AF_INET ?
 576             "reass frag %d @ %d-%d\n" : "reass frag %#08x @ %d-%d\n",
 577             key->frc_id, frent->fe_off, frent->fe_off + frent->fe_len));
 578
 579         /* Fully buffer all of the fragments in this fragment queue. */
 580         frag = pf_find_fragment(key, &V_pf_frag_tree);
 581
 582         /* Create a new reassembly queue for this packet. */
 583         if (frag == NULL) {
 584                 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 585                 if (frag == NULL) {
 586                         pf_flush_fragments();
 587                         frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 588                         if (frag == NULL) {
 589                                 REASON_SET(reason, PFRES_MEMORY);
 590                                 goto drop_fragment;
 591                         }
 592                 }
 593
 594                 *(struct pf_fragment_cmp *)frag = *key;
 595                 memset(frag->fr_firstoff, 0, sizeof(frag->fr_firstoff));
 596                 memset(frag->fr_entries, 0, sizeof(frag->fr_entries));
 597                 frag->fr_timeout = time_uptime;
 598                 frag->fr_maxlen = frent->fe_len;
 599                 frag->fr_holes = 1;
 600                 TAILQ_INIT(&frag->fr_queue);
 601
 602                 RB_INSERT(pf_frag_tree, &V_pf_frag_tree, frag);
 603                 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
 604
 605                 /* We do not have a previous fragment, cannot fail. */
 606                 pf_frent_insert(frag, frent, NULL);
 607
 608                 return (frag);
 609         }
 610
 611         KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue"));
 612
 613         /* Remember maximum fragment len for refragmentation. */
 614         if (frent->fe_len > frag->fr_maxlen)
 615                 frag->fr_maxlen = frent->fe_len;
 616
 617         /* Maximum data we have seen already. */
 618         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 619                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 620
 621         /* Non terminal fragments must have more fragments flag. */
 622         if (frent->fe_off + frent->fe_len < total && !frent->fe_mff)
 623                 goto bad_fragment;
 624
 625         /* Check if we saw the last fragment already. */
 626         if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) {
 627                 if (frent->fe_off + frent->fe_len > total ||
 628                     (frent->fe_off + frent->fe_len == total && frent->fe_mff))
 629                         goto bad_fragment;
 630         } else {
 631                 if (frent->fe_off + frent->fe_len == total && !frent->fe_mff)
 632                         goto bad_fragment;
 633         }
 634
 635         /* Find neighbors for newly inserted fragment */
 636         prev = pf_frent_previous(frag, frent);
 637         if (prev == NULL) {
 638                 after = TAILQ_FIRST(&frag->fr_queue);
 639                 KASSERT(after != NULL, ("after != NULL"));
 640         } else {
 641                 after = TAILQ_NEXT(prev, fr_next);
 642         }
 643
 644         if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) {
 645                 uint16_t precut;
 646
 647                 precut = prev->fe_off + prev->fe_len - frent->fe_off;
 648                 if (precut >= frent->fe_len)
 649                         goto bad_fragment;
 650                 DPFPRINTF(("overlap -%d\n", precut));
 651                 m_adj(frent->fe_m, precut);
 652                 frent->fe_off += precut;
 653                 frent->fe_len -= precut;
 654         }
 655
 656         for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off;
 657             after = next) {
 658                 uint16_t aftercut;
 659
 660                 aftercut = frent->fe_off + frent->fe_len - after->fe_off;
 661                 DPFPRINTF(("adjust overlap %d\n", aftercut));
 662                 if (aftercut < after->fe_len) {
 663                         m_adj(after->fe_m, aftercut);
 664                         old_index = pf_frent_index(after);
 665                         after->fe_off += aftercut;
 666                         after->fe_len -= aftercut;
 667                         new_index = pf_frent_index(after);
 668                         if (old_index != new_index) {
 669                                 DPFPRINTF(("frag index %d, new %d",
 670                                     old_index, new_index));
 671                                 /* Fragment switched queue as fe_off changed */
 672                                 after->fe_off -= aftercut;
 673                                 after->fe_len += aftercut;
 674                                 /* Remove restored fragment from old queue */
 675                                 pf_frent_remove(frag, after);
 676                                 after->fe_off += aftercut;
 677                                 after->fe_len -= aftercut;
 678                                 /* Insert into correct queue */
 679                                 if (pf_frent_insert(frag, after, prev)) {
 680                                         DPFPRINTF(
 681                                             ("fragment requeue limit exceeded"));
 682                                         m_freem(after->fe_m);
 683                                         uma_zfree(V_pf_frent_z, after);
 684                                         /* There is not way to recover */
 685                                         goto bad_fragment;
 686                                 }
 687                         }
 688                         break;
 689                 }
 690
 691                 /* This fragment is completely overlapped, lose it. */
 692                 next = TAILQ_NEXT(after, fr_next);
 693                 pf_frent_remove(frag, after);
 694                 m_freem(after->fe_m);
 695                 uma_zfree(V_pf_frent_z, after);
 696         }
 697
 698         /* If part of the queue gets too long, there is not way to recover. */
 699         if (pf_frent_insert(frag, frent, prev)) {
 700                 DPFPRINTF(("fragment queue limit exceeded\n"));
 701                 goto bad_fragment;
 702         }
 703
 704         return (frag);
 705
 706 bad_fragment:
 707         REASON_SET(reason, PFRES_FRAG);
 708 drop_fragment:
 709         uma_zfree(V_pf_frent_z, frent);
 710         return (NULL);
 711 }
 712
 713 static struct mbuf *
 714 pf_join_fragment(struct pf_fragment *frag)
 715 {
 716         struct mbuf *m, *m2;
 717         struct pf_frent *frent, *next;
 718
 719         frent = TAILQ_FIRST(&frag->fr_queue);
 720         next = TAILQ_NEXT(frent, fr_next);
 721
 722         m = frent->fe_m;
 723         m_adj(m, (frent->fe_hdrlen + frent->fe_len) - m->m_pkthdr.len);
 724         uma_zfree(V_pf_frent_z, frent);
 725         for (frent = next; frent != NULL; frent = next) {
 726                 next = TAILQ_NEXT(frent, fr_next);
 727
 728                 m2 = frent->fe_m;
 729                 /* Strip off ip header. */
 730                 m_adj(m2, frent->fe_hdrlen);
 731                 /* Strip off any trailing bytes. */
 732                 m_adj(m2, frent->fe_len - m2->m_pkthdr.len);
 733
 734                 uma_zfree(V_pf_frent_z, frent);
 735                 m_cat(m, m2);
 736         }
 737
 738         /* Remove from fragment queue. */
 739         pf_remove_fragment(frag);
 740
 741         return (m);
 742 }
 743
 744 #ifdef INET
 745 static int
 746 pf_reassemble(struct mbuf **m0, struct ip *ip, int dir, u_short *reason)
 747 {
 748         struct mbuf             *m = *m0;
 749         struct pf_frent         *frent;
 750         struct pf_fragment      *frag;
 751         struct pf_fragment_cmp  key;
 752         uint16_t                total, hdrlen;
 753
 754         /* Get an entry for the fragment queue */
 755         if ((frent = pf_create_fragment(reason)) == NULL)
 756                 return (PF_DROP);
 757
 758         frent->fe_m = m;
 759         frent->fe_hdrlen = ip->ip_hl << 2;
 760         frent->fe_extoff = 0;
 761         frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2);
 762         frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3;
 763         frent->fe_mff = ntohs(ip->ip_off) & IP_MF;
 764
 765         pf_ip2key(ip, dir, &key);
 766
 767         if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL)
 768                 return (PF_DROP);
 769
 770         /* The mbuf is part of the fragment entry, no direct free or access */
 771         m = *m0 = NULL;
 772
 773         if (frag->fr_holes) {
 774                 DPFPRINTF(("frag %d, holes %d\n", frag->fr_id, frag->fr_holes));
 775                 return (PF_PASS);  /* drop because *m0 is NULL, no error */
 776         }
 777
 778         /* We have all the data */
 779         frent = TAILQ_FIRST(&frag->fr_queue);
 780         KASSERT(frent != NULL, ("frent != NULL"));
 781         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 782                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 783         hdrlen = frent->fe_hdrlen;
 784
 785         m = *m0 = pf_join_fragment(frag);
 786         frag = NULL;
 787
 788         if (m->m_flags & M_PKTHDR) {
 789                 int plen = 0;
 790                 for (m = *m0; m; m = m->m_next)
 791                         plen += m->m_len;
 792                 m = *m0;
 793                 m->m_pkthdr.len = plen;
 794         }
 795
 796         ip = mtod(m, struct ip *);
 797         ip->ip_sum = pf_cksum_fixup(ip->ip_sum, ip->ip_len,
 798             htons(hdrlen + total), 0);
 799         ip->ip_len = htons(hdrlen + total);
 800         ip->ip_sum = pf_cksum_fixup(ip->ip_sum, ip->ip_off,
 801             ip->ip_off & ~(IP_MF|IP_OFFMASK), 0);
 802         ip->ip_off &= ~(IP_MF|IP_OFFMASK);
 803
 804         if (hdrlen + total > IP_MAXPACKET) {
 805                 DPFPRINTF(("drop: too big: %d\n", total));
 806                 ip->ip_len = 0;
 807                 REASON_SET(reason, PFRES_SHORT);
 808                 /* PF_DROP requires a valid mbuf *m0 in pf_test() */
 809                 return (PF_DROP);
 810         }
 811
 812         DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len)));
 813         return (PF_PASS);
 814 }
 815 #endif  /* INET */
 816
 817 #ifdef INET6
 818 static int
 819 pf_reassemble6(struct mbuf **m0, struct ip6_hdr *ip6, struct ip6_frag *fraghdr,
 820     uint16_t hdrlen, uint16_t extoff, u_short *reason)
 821 {
 822         struct mbuf             *m = *m0;
 823         struct pf_frent         *frent;
 824         struct pf_fragment      *frag;
 825         struct pf_fragment_cmp   key;
 826         struct m_tag            *mtag;
 827         struct pf_fragment_tag  *ftag;
 828         int                      off;
 829         uint32_t                 frag_id;
 830         uint16_t                 total, maxlen;
 831         uint8_t                  proto;
 832
 833         PF_FRAG_LOCK();
 834
 835         /* Get an entry for the fragment queue. */
 836         if ((frent = pf_create_fragment(reason)) == NULL) {
 837                 PF_FRAG_UNLOCK();
 838                 return (PF_DROP);
 839         }
 840
 841         frent->fe_m = m;
 842         frent->fe_hdrlen = hdrlen;
 843         frent->fe_extoff = extoff;
 844         frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen;
 845         frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK);
 846         frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG;
 847
 848         key.frc_src.v6 = ip6->ip6_src;
 849         key.frc_dst.v6 = ip6->ip6_dst;
 850         key.frc_af = AF_INET6;
 851         /* Only the first fragment's protocol is relevant. */
 852         key.frc_proto = 0;
 853         key.frc_id = fraghdr->ip6f_ident;
 854
 855         if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) {
 856                 PF_FRAG_UNLOCK();
 857                 return (PF_DROP);
 858         }
 859
 860         /* The mbuf is part of the fragment entry, no direct free or access. */
 861         m = *m0 = NULL;
 862
 863         if (frag->fr_holes) {
 864                 DPFPRINTF(("frag %d, holes %d\n", frag->fr_id,
 865                     frag->fr_holes));
 866                 PF_FRAG_UNLOCK();
 867                 return (PF_PASS);  /* Drop because *m0 is NULL, no error. */
 868         }
 869
 870         /* We have all the data. */
 871         frent = TAILQ_FIRST(&frag->fr_queue);
 872         KASSERT(frent != NULL, ("frent != NULL"));
 873         extoff = frent->fe_extoff;
 874         maxlen = frag->fr_maxlen;
 875         frag_id = frag->fr_id;
 876         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 877                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 878         hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag);
 879
 880         m = *m0 = pf_join_fragment(frag);
 881         frag = NULL;
 882
 883         PF_FRAG_UNLOCK();
 884
 885         /* Take protocol from first fragment header. */
 886         m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off);
 887         KASSERT(m, ("%s: short mbuf chain", __func__));
 888         proto = *(mtod(m, uint8_t *) + off);
 889         m = *m0;
 890
 891         /* Delete frag6 header */
 892         if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0)
 893                 goto fail;
 894
 895         if (m->m_flags & M_PKTHDR) {
 896                 int plen = 0;
 897                 for (m = *m0; m; m = m->m_next)
 898                         plen += m->m_len;
 899                 m = *m0;
 900                 m->m_pkthdr.len = plen;
 901         }
 902
 903         if ((mtag = m_tag_get(PACKET_TAG_PF_REASSEMBLED,
 904             sizeof(struct pf_fragment_tag), M_NOWAIT)) == NULL)
 905                 goto fail;
 906         ftag = (struct pf_fragment_tag *)(mtag + 1);
 907         ftag->ft_hdrlen = hdrlen;
 908         ftag->ft_extoff = extoff;
 909         ftag->ft_maxlen = maxlen;
 910         ftag->ft_id = frag_id;
 911         m_tag_prepend(m, mtag);
 912
 913         ip6 = mtod(m, struct ip6_hdr *);
 914         ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total);
 915         if (extoff) {
 916                 /* Write protocol into next field of last extension header. */
 917                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
 918                     &off);
 919                 KASSERT(m, ("%s: short mbuf chain", __func__));
 920                 *(mtod(m, char *) + off) = proto;
 921                 m = *m0;
 922         } else
 923                 ip6->ip6_nxt = proto;
 924
 925         if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) {
 926                 DPFPRINTF(("drop: too big: %d\n", total));
 927                 ip6->ip6_plen = 0;
 928                 REASON_SET(reason, PFRES_SHORT);
 929                 /* PF_DROP requires a valid mbuf *m0 in pf_test6(). */
 930                 return (PF_DROP);
 931         }
 932
 933         DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip6->ip6_plen)));
 934         return (PF_PASS);
 935
 936 fail:
 937         REASON_SET(reason, PFRES_MEMORY);
 938         /* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */
 939         return (PF_DROP);
 940 }
 941 #endif  /* INET6 */
 942
 943 #ifdef INET6
 944 int
 945 pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag,
 946     bool forward)
 947 {
 948         struct mbuf             *m = *m0, *t;
 949         struct ip6_hdr          *hdr;
 950         struct pf_fragment_tag  *ftag = (struct pf_fragment_tag *)(mtag + 1);
 951         struct pf_pdesc          pd;
 952         uint32_t                 frag_id;
 953         uint16_t                 hdrlen, extoff, maxlen;
 954         uint8_t                  proto;
 955         int                      error, action;
 956
 957         hdrlen = ftag->ft_hdrlen;
 958         extoff = ftag->ft_extoff;
 959         maxlen = ftag->ft_maxlen;
 960         frag_id = ftag->ft_id;
 961         m_tag_delete(m, mtag);
 962         mtag = NULL;
 963         ftag = NULL;
 964
 965         if (extoff) {
 966                 int off;
 967
 968                 /* Use protocol from next field of last extension header */
 969                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
 970                     &off);
 971                 KASSERT((m != NULL), ("pf_refragment6: short mbuf chain"));
 972                 proto = *(mtod(m, uint8_t *) + off);
 973                 *(mtod(m, char *) + off) = IPPROTO_FRAGMENT;
 974                 m = *m0;
 975         } else {
 976                 hdr = mtod(m, struct ip6_hdr *);
 977                 proto = hdr->ip6_nxt;
 978                 hdr->ip6_nxt = IPPROTO_FRAGMENT;
 979         }
 980
 981         /* In case of link-local traffic we'll need a scope set. */
 982         hdr = mtod(m, struct ip6_hdr *);
 983
 984         in6_setscope(&hdr->ip6_src, ifp, NULL);
 985         in6_setscope(&hdr->ip6_dst, ifp, NULL);
 986
 987         /* The MTU must be a multiple of 8 bytes, or we risk doing the
 988          * fragmentation wrong. */
 989         maxlen = maxlen & ~7;
 990
 991         /*
 992          * Maxlen may be less than 8 if there was only a single
 993          * fragment.  As it was fragmented before, add a fragment
 994          * header also for a single fragment.  If total or maxlen
 995          * is less than 8, ip6_fragment() will return EMSGSIZE and
 996          * we drop the packet.
 997          */
 998         error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id);
 999         m = (*m0)->m_nextpkt;
1000         (*m0)->m_nextpkt = NULL;
1001         if (error == 0) {
1002                 /* The first mbuf contains the unfragmented packet. */
1003                 m_freem(*m0);
1004                 *m0 = NULL;
1005                 action = PF_PASS;
1006         } else {
1007                 /* Drop expects an mbuf to free. */
1008                 DPFPRINTF(("refragment error %d\n", error));
1009                 action = PF_DROP;
1010         }
1011         for (; m; m = t) {
1012                 t = m->m_nextpkt;
1013                 m->m_nextpkt = NULL;
1014                 m->m_flags |= M_SKIP_FIREWALL;
1015                 memset(&pd, 0, sizeof(pd));
1016                 pd.pf_mtag = pf_find_mtag(m);
1017                 if (error == 0)
1018                         if (forward) {
1019                                 MPASS(m->m_pkthdr.rcvif != NULL);
1020                                 ip6_forward(m, 0);
1021                         } else {
1022                                 (void)ip6_output(m, NULL, NULL, 0, NULL, NULL,
1023                                     NULL);
1024                         }
1025                 else
1026                         m_freem(m);
1027         }
1028
1029         return (action);
1030 }
1031 #endif /* INET6 */
1032
1033 #ifdef INET
1034 int
1035 pf_normalize_ip(struct mbuf **m0, struct pfi_kkif *kif, u_short *reason,
1036     struct pf_pdesc *pd)
1037 {
1038         struct mbuf             *m = *m0;
1039         struct pf_krule         *r;
1040         struct ip               *h = mtod(m, struct ip *);
1041         int                      mff = (ntohs(h->ip_off) & IP_MF);
1042         int                      hlen = h->ip_hl << 2;
1043         u_int16_t                fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
1044         u_int16_t                max;
1045         int                      ip_len;
1046         int                      tag = -1;
1047         int                      verdict;
1048         int                      srs;
1049
1050         PF_RULES_RASSERT();
1051
1052         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1053         /* Check if there any scrub rules. Lack of scrub rules means enforced
1054          * packet normalization operation just like in OpenBSD. */
1055         srs = (r != NULL);
1056         while (r != NULL) {
1057                 pf_counter_u64_add(&r->evaluations, 1);
1058                 if (pfi_kkif_match(r->kif, kif) == r->ifnot)
1059                         r = r->skip[PF_SKIP_IFP].ptr;
1060                 else if (r->direction && r->direction != pd->dir)
1061                         r = r->skip[PF_SKIP_DIR].ptr;
1062                 else if (r->af && r->af != AF_INET)
1063                         r = r->skip[PF_SKIP_AF].ptr;
1064                 else if (r->proto && r->proto != h->ip_p)
1065                         r = r->skip[PF_SKIP_PROTO].ptr;
1066                 else if (PF_MISMATCHAW(&r->src.addr,
1067                     (struct pf_addr *)&h->ip_src.s_addr, AF_INET,
1068                     r->src.neg, kif, M_GETFIB(m)))
1069                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1070                 else if (PF_MISMATCHAW(&r->dst.addr,
1071                     (struct pf_addr *)&h->ip_dst.s_addr, AF_INET,
1072                     r->dst.neg, NULL, M_GETFIB(m)))
1073                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1074                 else if (r->match_tag && !pf_match_tag(m, r, &tag,
1075                     pd->pf_mtag ? pd->pf_mtag->tag : 0))
1076                         r = TAILQ_NEXT(r, entries);
1077                 else
1078                         break;
1079         }
1080
1081         if (srs) {
1082                 /* With scrub rules present IPv4 normalization happens only
1083                  * if one of rules has matched and it's not a "no scrub" rule */
1084                 if (r == NULL || r->action == PF_NOSCRUB)
1085                         return (PF_PASS);
1086
1087                 pf_counter_u64_critical_enter();
1088                 pf_counter_u64_add_protected(&r->packets[pd->dir == PF_OUT], 1);
1089                 pf_counter_u64_add_protected(&r->bytes[pd->dir == PF_OUT], pd->tot_len);
1090                 pf_counter_u64_critical_exit();
1091                 pf_rule_to_actions(r, &pd->act);
1092         } else if ((!V_pf_status.reass && (h->ip_off & htons(IP_MF | IP_OFFMASK)))) {
1093                 /* With no scrub rules IPv4 fragment reassembly depends on the
1094                  * global switch. Fragments can be dropped early if reassembly
1095                  * is disabled. */
1096                 REASON_SET(reason, PFRES_NORM);
1097                 goto drop;
1098         }
1099
1100         /* Check for illegal packets */
1101         if (hlen < (int)sizeof(struct ip)) {
1102                 REASON_SET(reason, PFRES_NORM);
1103                 goto drop;
1104         }
1105
1106         if (hlen > ntohs(h->ip_len)) {
1107                 REASON_SET(reason, PFRES_NORM);
1108                 goto drop;
1109         }
1110
1111         /* Clear IP_DF if the rule uses the no-df option or we're in no-df mode */
1112         if ((((r && r->rule_flag & PFRULE_NODF) ||
1113             (V_pf_status.reass & PF_REASS_NODF)) && h->ip_off & htons(IP_DF)
1114         )) {
1115                 u_int16_t ip_off = h->ip_off;
1116
1117                 h->ip_off &= htons(~IP_DF);
1118                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1119         }
1120
1121         /* We will need other tests here */
1122         if (!fragoff && !mff)
1123                 goto no_fragment;
1124
1125         /* We're dealing with a fragment now. Don't allow fragments
1126          * with IP_DF to enter the cache. If the flag was cleared by
1127          * no-df above, fine. Otherwise drop it.
1128          */
1129         if (h->ip_off & htons(IP_DF)) {
1130                 DPFPRINTF(("IP_DF\n"));
1131                 goto bad;
1132         }
1133
1134         ip_len = ntohs(h->ip_len) - hlen;
1135
1136         /* All fragments are 8 byte aligned */
1137         if (mff && (ip_len & 0x7)) {
1138                 DPFPRINTF(("mff and %d\n", ip_len));
1139                 goto bad;
1140         }
1141
1142         /* Respect maximum length */
1143         if (fragoff + ip_len > IP_MAXPACKET) {
1144                 DPFPRINTF(("max packet %d\n", fragoff + ip_len));
1145                 goto bad;
1146         }
1147
1148         if (r==NULL || !(r->rule_flag & PFRULE_FRAGMENT_NOREASS)) {
1149                 max = fragoff + ip_len;
1150
1151                 /* Fully buffer all of the fragments
1152                  * Might return a completely reassembled mbuf, or NULL */
1153                 PF_FRAG_LOCK();
1154                 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
1155                 verdict = pf_reassemble(m0, h, pd->dir, reason);
1156                 PF_FRAG_UNLOCK();
1157
1158                 if (verdict != PF_PASS)
1159                         return (PF_DROP);
1160
1161                 m = *m0;
1162                 if (m == NULL)
1163                         return (PF_DROP);
1164
1165                 h = mtod(m, struct ip *);
1166
1167  no_fragment:
1168                 /* At this point, only IP_DF is allowed in ip_off */
1169                 if (h->ip_off & ~htons(IP_DF)) {
1170                         u_int16_t ip_off = h->ip_off;
1171
1172                         h->ip_off &= htons(IP_DF);
1173                         h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1174                 }
1175         }
1176
1177         return (PF_PASS);
1178
1179  bad:
1180         DPFPRINTF(("dropping bad fragment\n"));
1181         REASON_SET(reason, PFRES_FRAG);
1182  drop:
1183         if (r != NULL && r->log)
1184                 PFLOG_PACKET(kif, m, AF_INET, *reason, r, NULL, NULL, pd, 1);
1185
1186         return (PF_DROP);
1187 }
1188 #endif
1189
1190 #ifdef INET6
1191 int
1192 pf_normalize_ip6(struct mbuf **m0, struct pfi_kkif *kif,
1193     u_short *reason, struct pf_pdesc *pd)
1194 {
1195         struct mbuf             *m = *m0;
1196         struct pf_krule         *r;
1197         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
1198         int                      extoff;
1199         int                      off;
1200         struct ip6_ext           ext;
1201         struct ip6_opt           opt;
1202         struct ip6_frag          frag;
1203         u_int32_t                plen;
1204         int                      optend;
1205         int                      ooff;
1206         u_int8_t                 proto;
1207         int                      terminal;
1208         int                      srs;
1209
1210         PF_RULES_RASSERT();
1211
1212         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1213         /* Check if there any scrub rules. Lack of scrub rules means enforced
1214          * packet normalization operation just like in OpenBSD. */
1215         srs = (r != NULL);
1216         while (r != NULL) {
1217                 pf_counter_u64_add(&r->evaluations, 1);
1218                 if (pfi_kkif_match(r->kif, kif) == r->ifnot)
1219                         r = r->skip[PF_SKIP_IFP].ptr;
1220                 else if (r->direction && r->direction != pd->dir)
1221                         r = r->skip[PF_SKIP_DIR].ptr;
1222                 else if (r->af && r->af != AF_INET6)
1223                         r = r->skip[PF_SKIP_AF].ptr;
1224 #if 0 /* header chain! */
1225                 else if (r->proto && r->proto != h->ip6_nxt)
1226                         r = r->skip[PF_SKIP_PROTO].ptr;
1227 #endif
1228                 else if (PF_MISMATCHAW(&r->src.addr,
1229                     (struct pf_addr *)&h->ip6_src, AF_INET6,
1230                     r->src.neg, kif, M_GETFIB(m)))
1231                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1232                 else if (PF_MISMATCHAW(&r->dst.addr,
1233                     (struct pf_addr *)&h->ip6_dst, AF_INET6,
1234                     r->dst.neg, NULL, M_GETFIB(m)))
1235                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1236                 else
1237                         break;
1238         }
1239
1240         if (srs) {
1241                 /* With scrub rules present IPv6 normalization happens only
1242                  * if one of rules has matched and it's not a "no scrub" rule */
1243                 if (r == NULL || r->action == PF_NOSCRUB)
1244                         return (PF_PASS);
1245
1246                 pf_counter_u64_critical_enter();
1247                 pf_counter_u64_add_protected(&r->packets[pd->dir == PF_OUT], 1);
1248                 pf_counter_u64_add_protected(&r->bytes[pd->dir == PF_OUT], pd->tot_len);
1249                 pf_counter_u64_critical_exit();
1250                 pf_rule_to_actions(r, &pd->act);
1251         }
1252
1253         /* Check for illegal packets */
1254         if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len)
1255                 goto drop;
1256
1257 again:
1258         h = mtod(m, struct ip6_hdr *);
1259         plen = ntohs(h->ip6_plen);
1260         /* jumbo payload option not supported */
1261         if (plen == 0)
1262                 goto drop;
1263
1264         extoff = 0;
1265         off = sizeof(struct ip6_hdr);
1266         proto = h->ip6_nxt;
1267         terminal = 0;
1268         do {
1269                 switch (proto) {
1270                 case IPPROTO_FRAGMENT:
1271                         goto fragment;
1272                         break;
1273                 case IPPROTO_AH:
1274                 case IPPROTO_ROUTING:
1275                 case IPPROTO_DSTOPTS:
1276                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1277                             NULL, AF_INET6))
1278                                 goto shortpkt;
1279                         extoff = off;
1280                         if (proto == IPPROTO_AH)
1281                                 off += (ext.ip6e_len + 2) * 4;
1282                         else
1283                                 off += (ext.ip6e_len + 1) * 8;
1284                         proto = ext.ip6e_nxt;
1285                         break;
1286                 case IPPROTO_HOPOPTS:
1287                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1288                             NULL, AF_INET6))
1289                                 goto shortpkt;
1290                         extoff = off;
1291                         optend = off + (ext.ip6e_len + 1) * 8;
1292                         ooff = off + sizeof(ext);
1293                         do {
1294                                 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type,
1295                                     sizeof(opt.ip6o_type), NULL, NULL,
1296                                     AF_INET6))
1297                                         goto shortpkt;
1298                                 if (opt.ip6o_type == IP6OPT_PAD1) {
1299                                         ooff++;
1300                                         continue;
1301                                 }
1302                                 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt),
1303                                     NULL, NULL, AF_INET6))
1304                                         goto shortpkt;
1305                                 if (ooff + sizeof(opt) + opt.ip6o_len > optend)
1306                                         goto drop;
1307                                 if (opt.ip6o_type == IP6OPT_JUMBO)
1308                                         goto drop;
1309                                 ooff += sizeof(opt) + opt.ip6o_len;
1310                         } while (ooff < optend);
1311
1312                         off = optend;
1313                         proto = ext.ip6e_nxt;
1314                         break;
1315                 default:
1316                         terminal = 1;
1317                         break;
1318                 }
1319         } while (!terminal);
1320
1321         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1322                 goto shortpkt;
1323
1324         return (PF_PASS);
1325
1326  fragment:
1327         if (pd->flags & PFDESC_IP_REAS)
1328                 return (PF_DROP);
1329         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1330                 goto shortpkt;
1331
1332         if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6))
1333                 goto shortpkt;
1334
1335         /* Offset now points to data portion. */
1336         off += sizeof(frag);
1337
1338         /* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */
1339         if (pf_reassemble6(m0, h, &frag, off, extoff, reason) != PF_PASS)
1340                 return (PF_DROP);
1341         m = *m0;
1342         if (m == NULL)
1343                 return (PF_DROP);
1344
1345         pd->flags |= PFDESC_IP_REAS;
1346         goto again;
1347
1348  shortpkt:
1349         REASON_SET(reason, PFRES_SHORT);
1350         if (r != NULL && r->log)
1351                 PFLOG_PACKET(kif, m, AF_INET6, *reason, r, NULL, NULL, pd, 1);
1352         return (PF_DROP);
1353
1354  drop:
1355         REASON_SET(reason, PFRES_NORM);
1356         if (r != NULL && r->log)
1357                 PFLOG_PACKET(kif, m, AF_INET6, *reason, r, NULL, NULL, pd, 1);
1358         return (PF_DROP);
1359 }
1360 #endif /* INET6 */
1361
1362 int
1363 pf_normalize_tcp(struct pfi_kkif *kif, struct mbuf *m, int ipoff,
1364     int off, void *h, struct pf_pdesc *pd)
1365 {
1366         struct pf_krule *r, *rm = NULL;
1367         struct tcphdr   *th = &pd->hdr.tcp;
1368         int              rewrite = 0;
1369         u_short          reason;
1370         u_int8_t         flags;
1371         sa_family_t      af = pd->af;
1372         int              srs;
1373
1374         PF_RULES_RASSERT();
1375
1376         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1377         /* Check if there any scrub rules. Lack of scrub rules means enforced
1378          * packet normalization operation just like in OpenBSD. */
1379         srs = (r != NULL);
1380         while (r != NULL) {
1381                 pf_counter_u64_add(&r->evaluations, 1);
1382                 if (pfi_kkif_match(r->kif, kif) == r->ifnot)
1383                         r = r->skip[PF_SKIP_IFP].ptr;
1384                 else if (r->direction && r->direction != pd->dir)
1385                         r = r->skip[PF_SKIP_DIR].ptr;
1386                 else if (r->af && r->af != af)
1387                         r = r->skip[PF_SKIP_AF].ptr;
1388                 else if (r->proto && r->proto != pd->proto)
1389                         r = r->skip[PF_SKIP_PROTO].ptr;
1390                 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af,
1391                     r->src.neg, kif, M_GETFIB(m)))
1392                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1393                 else if (r->src.port_op && !pf_match_port(r->src.port_op,
1394                             r->src.port[0], r->src.port[1], th->th_sport))
1395                         r = r->skip[PF_SKIP_SRC_PORT].ptr;
1396                 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af,
1397                     r->dst.neg, NULL, M_GETFIB(m)))
1398                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1399                 else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
1400                             r->dst.port[0], r->dst.port[1], th->th_dport))
1401                         r = r->skip[PF_SKIP_DST_PORT].ptr;
1402                 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match(
1403                             pf_osfp_fingerprint(pd, m, off, th),
1404                             r->os_fingerprint))
1405                         r = TAILQ_NEXT(r, entries);
1406                 else {
1407                         rm = r;
1408                         break;
1409                 }
1410         }
1411
1412         if (srs) {
1413                 /* With scrub rules present TCP normalization happens only
1414                  * if one of rules has matched and it's not a "no scrub" rule */
1415                 if (rm == NULL || rm->action == PF_NOSCRUB)
1416                         return (PF_PASS);
1417
1418                 pf_counter_u64_critical_enter();
1419                 pf_counter_u64_add_protected(&r->packets[pd->dir == PF_OUT], 1);
1420                 pf_counter_u64_add_protected(&r->bytes[pd->dir == PF_OUT], pd->tot_len);
1421                 pf_counter_u64_critical_exit();
1422                 pf_rule_to_actions(rm, &pd->act);
1423         }
1424
1425         if (rm && rm->rule_flag & PFRULE_REASSEMBLE_TCP)
1426                 pd->flags |= PFDESC_TCP_NORM;
1427
1428         flags = th->th_flags;
1429         if (flags & TH_SYN) {
1430                 /* Illegal packet */
1431                 if (flags & TH_RST)
1432                         goto tcp_drop;
1433
1434                 if (flags & TH_FIN)
1435                         goto tcp_drop;
1436         } else {
1437                 /* Illegal packet */
1438                 if (!(flags & (TH_ACK|TH_RST)))
1439                         goto tcp_drop;
1440         }
1441
1442         if (!(flags & TH_ACK)) {
1443                 /* These flags are only valid if ACK is set */
1444                 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG))
1445                         goto tcp_drop;
1446         }
1447
1448         /* Check for illegal header length */
1449         if (th->th_off < (sizeof(struct tcphdr) >> 2))
1450                 goto tcp_drop;
1451
1452         /* If flags changed, or reserved data set, then adjust */
1453         if (flags != th->th_flags || th->th_x2 != 0) {
1454                 u_int16_t       ov, nv;
1455
1456                 ov = *(u_int16_t *)(&th->th_ack + 1);
1457                 th->th_flags = flags;
1458                 th->th_x2 = 0;
1459                 nv = *(u_int16_t *)(&th->th_ack + 1);
1460
1461                 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, ov, nv, 0);
1462                 rewrite = 1;
1463         }
1464
1465         /* Remove urgent pointer, if TH_URG is not set */
1466         if (!(flags & TH_URG) && th->th_urp) {
1467                 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, th->th_urp,
1468                     0, 0);
1469                 th->th_urp = 0;
1470                 rewrite = 1;
1471         }
1472
1473         /* copy back packet headers if we sanitized */
1474         if (rewrite)
1475                 m_copyback(m, off, sizeof(*th), (caddr_t)th);
1476
1477         return (PF_PASS);
1478
1479  tcp_drop:
1480         REASON_SET(&reason, PFRES_NORM);
1481         if (rm != NULL && r->log)
1482                 PFLOG_PACKET(kif, m, AF_INET, reason, r, NULL, NULL, pd, 1);
1483         return (PF_DROP);
1484 }
1485
1486 int
1487 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd,
1488     struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst)
1489 {
1490         u_int32_t tsval, tsecr;
1491         u_int8_t hdr[60];
1492         u_int8_t *opt;
1493
1494         KASSERT((src->scrub == NULL),
1495             ("pf_normalize_tcp_init: src->scrub != NULL"));
1496
1497         src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT);
1498         if (src->scrub == NULL)
1499                 return (1);
1500
1501         switch (pd->af) {
1502 #ifdef INET
1503         case AF_INET: {
1504                 struct ip *h = mtod(m, struct ip *);
1505                 src->scrub->pfss_ttl = h->ip_ttl;
1506                 break;
1507         }
1508 #endif /* INET */
1509 #ifdef INET6
1510         case AF_INET6: {
1511                 struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1512                 src->scrub->pfss_ttl = h->ip6_hlim;
1513                 break;
1514         }
1515 #endif /* INET6 */
1516         }
1517
1518         /*
1519          * All normalizations below are only begun if we see the start of
1520          * the connections.  They must all set an enabled bit in pfss_flags
1521          */
1522         if ((th->th_flags & TH_SYN) == 0)
1523                 return (0);
1524
1525         if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub &&
1526             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1527                 /* Diddle with TCP options */
1528                 int hlen;
1529                 opt = hdr + sizeof(struct tcphdr);
1530                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1531                 while (hlen >= TCPOLEN_TIMESTAMP) {
1532                         switch (*opt) {
1533                         case TCPOPT_EOL:        /* FALLTHROUGH */
1534                         case TCPOPT_NOP:
1535                                 opt++;
1536                                 hlen--;
1537                                 break;
1538                         case TCPOPT_TIMESTAMP:
1539                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1540                                         src->scrub->pfss_flags |=
1541                                             PFSS_TIMESTAMP;
1542                                         src->scrub->pfss_ts_mod =
1543                                             htonl(arc4random());
1544
1545                                         /* note PFSS_PAWS not set yet */
1546                                         memcpy(&tsval, &opt[2],
1547                                             sizeof(u_int32_t));
1548                                         memcpy(&tsecr, &opt[6],
1549                                             sizeof(u_int32_t));
1550                                         src->scrub->pfss_tsval0 = ntohl(tsval);
1551                                         src->scrub->pfss_tsval = ntohl(tsval);
1552                                         src->scrub->pfss_tsecr = ntohl(tsecr);
1553                                         getmicrouptime(&src->scrub->pfss_last);
1554                                 }
1555                                 /* FALLTHROUGH */
1556                         default:
1557                                 hlen -= MAX(opt[1], 2);
1558                                 opt += MAX(opt[1], 2);
1559                                 break;
1560                         }
1561                 }
1562         }
1563
1564         return (0);
1565 }
1566
1567 void
1568 pf_normalize_tcp_cleanup(struct pf_kstate *state)
1569 {
1570         uma_zfree(V_pf_state_scrub_z, state->src.scrub);
1571         uma_zfree(V_pf_state_scrub_z, state->dst.scrub);
1572
1573         /* Someday... flush the TCP segment reassembly descriptors. */
1574 }
1575
1576 int
1577 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd,
1578     u_short *reason, struct tcphdr *th, struct pf_kstate *state,
1579     struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback)
1580 {
1581         struct timeval uptime;
1582         u_int32_t tsval, tsecr;
1583         u_int tsval_from_last;
1584         u_int8_t hdr[60];
1585         u_int8_t *opt;
1586         int copyback = 0;
1587         int got_ts = 0;
1588         size_t startoff;
1589
1590         KASSERT((src->scrub || dst->scrub),
1591             ("%s: src->scrub && dst->scrub!", __func__));
1592
1593         /*
1594          * Enforce the minimum TTL seen for this connection.  Negate a common
1595          * technique to evade an intrusion detection system and confuse
1596          * firewall state code.
1597          */
1598         switch (pd->af) {
1599 #ifdef INET
1600         case AF_INET: {
1601                 if (src->scrub) {
1602                         struct ip *h = mtod(m, struct ip *);
1603                         if (h->ip_ttl > src->scrub->pfss_ttl)
1604                                 src->scrub->pfss_ttl = h->ip_ttl;
1605                         h->ip_ttl = src->scrub->pfss_ttl;
1606                 }
1607                 break;
1608         }
1609 #endif /* INET */
1610 #ifdef INET6
1611         case AF_INET6: {
1612                 if (src->scrub) {
1613                         struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1614                         if (h->ip6_hlim > src->scrub->pfss_ttl)
1615                                 src->scrub->pfss_ttl = h->ip6_hlim;
1616                         h->ip6_hlim = src->scrub->pfss_ttl;
1617                 }
1618                 break;
1619         }
1620 #endif /* INET6 */
1621         }
1622
1623         if (th->th_off > (sizeof(struct tcphdr) >> 2) &&
1624             ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) ||
1625             (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) &&
1626             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1627                 /* Diddle with TCP options */
1628                 int hlen;
1629                 opt = hdr + sizeof(struct tcphdr);
1630                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1631                 while (hlen >= TCPOLEN_TIMESTAMP) {
1632                         startoff = opt - (hdr + sizeof(struct tcphdr));
1633                         switch (*opt) {
1634                         case TCPOPT_EOL:        /* FALLTHROUGH */
1635                         case TCPOPT_NOP:
1636                                 opt++;
1637                                 hlen--;
1638                                 break;
1639                         case TCPOPT_TIMESTAMP:
1640                                 /* Modulate the timestamps.  Can be used for
1641                                  * NAT detection, OS uptime determination or
1642                                  * reboot detection.
1643                                  */
1644
1645                                 if (got_ts) {
1646                                         /* Huh?  Multiple timestamps!? */
1647                                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1648                                                 DPFPRINTF(("multiple TS??\n"));
1649                                                 pf_print_state(state);
1650                                                 printf("\n");
1651                                         }
1652                                         REASON_SET(reason, PFRES_TS);
1653                                         return (PF_DROP);
1654                                 }
1655                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1656                                         memcpy(&tsval, &opt[2],
1657                                             sizeof(u_int32_t));
1658                                         if (tsval && src->scrub &&
1659                                             (src->scrub->pfss_flags &
1660                                             PFSS_TIMESTAMP)) {
1661                                                 tsval = ntohl(tsval);
1662                                                 pf_patch_32_unaligned(m,
1663                                                     &th->th_sum,
1664                                                     &opt[2],
1665                                                     htonl(tsval +
1666                                                     src->scrub->pfss_ts_mod),
1667                                                     PF_ALGNMNT(startoff),
1668                                                     0);
1669                                                 copyback = 1;
1670                                         }
1671
1672                                         /* Modulate TS reply iff valid (!0) */
1673                                         memcpy(&tsecr, &opt[6],
1674                                             sizeof(u_int32_t));
1675                                         if (tsecr && dst->scrub &&
1676                                             (dst->scrub->pfss_flags &
1677                                             PFSS_TIMESTAMP)) {
1678                                                 tsecr = ntohl(tsecr)
1679                                                     - dst->scrub->pfss_ts_mod;
1680                                                 pf_patch_32_unaligned(m,
1681                                                     &th->th_sum,
1682                                                     &opt[6],
1683                                                     htonl(tsecr),
1684                                                     PF_ALGNMNT(startoff),
1685                                                     0);
1686                                                 copyback = 1;
1687                                         }
1688                                         got_ts = 1;
1689                                 }
1690                                 /* FALLTHROUGH */
1691                         default:
1692                                 hlen -= MAX(opt[1], 2);
1693                                 opt += MAX(opt[1], 2);
1694                                 break;
1695                         }
1696                 }
1697                 if (copyback) {
1698                         /* Copyback the options, caller copys back header */
1699                         *writeback = 1;
1700                         m_copyback(m, off + sizeof(struct tcphdr),
1701                             (th->th_off << 2) - sizeof(struct tcphdr), hdr +
1702                             sizeof(struct tcphdr));
1703                 }
1704         }
1705
1706         /*
1707          * Must invalidate PAWS checks on connections idle for too long.
1708          * The fastest allowed timestamp clock is 1ms.  That turns out to
1709          * be about 24 days before it wraps.  XXX Right now our lowerbound
1710          * TS echo check only works for the first 12 days of a connection
1711          * when the TS has exhausted half its 32bit space
1712          */
1713 #define TS_MAX_IDLE     (24*24*60*60)
1714 #define TS_MAX_CONN     (12*24*60*60)   /* XXX remove when better tsecr check */
1715
1716         getmicrouptime(&uptime);
1717         if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) &&
1718             (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE ||
1719             time_uptime - state->creation > TS_MAX_CONN))  {
1720                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1721                         DPFPRINTF(("src idled out of PAWS\n"));
1722                         pf_print_state(state);
1723                         printf("\n");
1724                 }
1725                 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS)
1726                     | PFSS_PAWS_IDLED;
1727         }
1728         if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) &&
1729             uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) {
1730                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1731                         DPFPRINTF(("dst idled out of PAWS\n"));
1732                         pf_print_state(state);
1733                         printf("\n");
1734                 }
1735                 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS)
1736                     | PFSS_PAWS_IDLED;
1737         }
1738
1739         if (got_ts && src->scrub && dst->scrub &&
1740             (src->scrub->pfss_flags & PFSS_PAWS) &&
1741             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1742                 /* Validate that the timestamps are "in-window".
1743                  * RFC1323 describes TCP Timestamp options that allow
1744                  * measurement of RTT (round trip time) and PAWS
1745                  * (protection against wrapped sequence numbers).  PAWS
1746                  * gives us a set of rules for rejecting packets on
1747                  * long fat pipes (packets that were somehow delayed
1748                  * in transit longer than the time it took to send the
1749                  * full TCP sequence space of 4Gb).  We can use these
1750                  * rules and infer a few others that will let us treat
1751                  * the 32bit timestamp and the 32bit echoed timestamp
1752                  * as sequence numbers to prevent a blind attacker from
1753                  * inserting packets into a connection.
1754                  *
1755                  * RFC1323 tells us:
1756                  *  - The timestamp on this packet must be greater than
1757                  *    or equal to the last value echoed by the other
1758                  *    endpoint.  The RFC says those will be discarded
1759                  *    since it is a dup that has already been acked.
1760                  *    This gives us a lowerbound on the timestamp.
1761                  *        timestamp >= other last echoed timestamp
1762                  *  - The timestamp will be less than or equal to
1763                  *    the last timestamp plus the time between the
1764                  *    last packet and now.  The RFC defines the max
1765                  *    clock rate as 1ms.  We will allow clocks to be
1766                  *    up to 10% fast and will allow a total difference
1767                  *    or 30 seconds due to a route change.  And this
1768                  *    gives us an upperbound on the timestamp.
1769                  *        timestamp <= last timestamp + max ticks
1770                  *    We have to be careful here.  Windows will send an
1771                  *    initial timestamp of zero and then initialize it
1772                  *    to a random value after the 3whs; presumably to
1773                  *    avoid a DoS by having to call an expensive RNG
1774                  *    during a SYN flood.  Proof MS has at least one
1775                  *    good security geek.
1776                  *
1777                  *  - The TCP timestamp option must also echo the other
1778                  *    endpoints timestamp.  The timestamp echoed is the
1779                  *    one carried on the earliest unacknowledged segment
1780                  *    on the left edge of the sequence window.  The RFC
1781                  *    states that the host will reject any echoed
1782                  *    timestamps that were larger than any ever sent.
1783                  *    This gives us an upperbound on the TS echo.
1784                  *        tescr <= largest_tsval
1785                  *  - The lowerbound on the TS echo is a little more
1786                  *    tricky to determine.  The other endpoint's echoed
1787                  *    values will not decrease.  But there may be
1788                  *    network conditions that re-order packets and
1789                  *    cause our view of them to decrease.  For now the
1790                  *    only lowerbound we can safely determine is that
1791                  *    the TS echo will never be less than the original
1792                  *    TS.  XXX There is probably a better lowerbound.
1793                  *    Remove TS_MAX_CONN with better lowerbound check.
1794                  *        tescr >= other original TS
1795                  *
1796                  * It is also important to note that the fastest
1797                  * timestamp clock of 1ms will wrap its 32bit space in
1798                  * 24 days.  So we just disable TS checking after 24
1799                  * days of idle time.  We actually must use a 12d
1800                  * connection limit until we can come up with a better
1801                  * lowerbound to the TS echo check.
1802                  */
1803                 struct timeval delta_ts;
1804                 int ts_fudge;
1805
1806                 /*
1807                  * PFTM_TS_DIFF is how many seconds of leeway to allow
1808                  * a host's timestamp.  This can happen if the previous
1809                  * packet got delayed in transit for much longer than
1810                  * this packet.
1811                  */
1812                 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0)
1813                         ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF];
1814
1815                 /* Calculate max ticks since the last timestamp */
1816 #define TS_MAXFREQ      1100            /* RFC max TS freq of 1Khz + 10% skew */
1817 #define TS_MICROSECS    1000000         /* microseconds per second */
1818                 delta_ts = uptime;
1819                 timevalsub(&delta_ts, &src->scrub->pfss_last);
1820                 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ;
1821                 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ);
1822
1823                 if ((src->state >= TCPS_ESTABLISHED &&
1824                     dst->state >= TCPS_ESTABLISHED) &&
1825                     (SEQ_LT(tsval, dst->scrub->pfss_tsecr) ||
1826                     SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) ||
1827                     (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) ||
1828                     SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) {
1829                         /* Bad RFC1323 implementation or an insertion attack.
1830                          *
1831                          * - Solaris 2.6 and 2.7 are known to send another ACK
1832                          *   after the FIN,FIN|ACK,ACK closing that carries
1833                          *   an old timestamp.
1834                          */
1835
1836                         DPFPRINTF(("Timestamp failed %c%c%c%c\n",
1837                             SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ',
1838                             SEQ_GT(tsval, src->scrub->pfss_tsval +
1839                             tsval_from_last) ? '1' : ' ',
1840                             SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ',
1841                             SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' '));
1842                         DPFPRINTF((" tsval: %u  tsecr: %u  +ticks: %u  "
1843                             "idle: %jus %lums\n",
1844                             tsval, tsecr, tsval_from_last,
1845                             (uintmax_t)delta_ts.tv_sec,
1846                             delta_ts.tv_usec / 1000));
1847                         DPFPRINTF((" src->tsval: %u  tsecr: %u\n",
1848                             src->scrub->pfss_tsval, src->scrub->pfss_tsecr));
1849                         DPFPRINTF((" dst->tsval: %u  tsecr: %u  tsval0: %u"
1850                             "\n", dst->scrub->pfss_tsval,
1851                             dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0));
1852                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1853                                 pf_print_state(state);
1854                                 pf_print_flags(th->th_flags);
1855                                 printf("\n");
1856                         }
1857                         REASON_SET(reason, PFRES_TS);
1858                         return (PF_DROP);
1859                 }
1860
1861                 /* XXX I'd really like to require tsecr but it's optional */
1862
1863         } else if (!got_ts && (th->th_flags & TH_RST) == 0 &&
1864             ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED)
1865             || pd->p_len > 0 || (th->th_flags & TH_SYN)) &&
1866             src->scrub && dst->scrub &&
1867             (src->scrub->pfss_flags & PFSS_PAWS) &&
1868             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1869                 /* Didn't send a timestamp.  Timestamps aren't really useful
1870                  * when:
1871                  *  - connection opening or closing (often not even sent).
1872                  *    but we must not let an attacker to put a FIN on a
1873                  *    data packet to sneak it through our ESTABLISHED check.
1874                  *  - on a TCP reset.  RFC suggests not even looking at TS.
1875                  *  - on an empty ACK.  The TS will not be echoed so it will
1876                  *    probably not help keep the RTT calculation in sync and
1877                  *    there isn't as much danger when the sequence numbers
1878                  *    got wrapped.  So some stacks don't include TS on empty
1879                  *    ACKs :-(
1880                  *
1881                  * To minimize the disruption to mostly RFC1323 conformant
1882                  * stacks, we will only require timestamps on data packets.
1883                  *
1884                  * And what do ya know, we cannot require timestamps on data
1885                  * packets.  There appear to be devices that do legitimate
1886                  * TCP connection hijacking.  There are HTTP devices that allow
1887                  * a 3whs (with timestamps) and then buffer the HTTP request.
1888                  * If the intermediate device has the HTTP response cache, it
1889                  * will spoof the response but not bother timestamping its
1890                  * packets.  So we can look for the presence of a timestamp in
1891                  * the first data packet and if there, require it in all future
1892                  * packets.
1893                  */
1894
1895                 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) {
1896                         /*
1897                          * Hey!  Someone tried to sneak a packet in.  Or the
1898                          * stack changed its RFC1323 behavior?!?!
1899                          */
1900                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1901                                 DPFPRINTF(("Did not receive expected RFC1323 "
1902                                     "timestamp\n"));
1903                                 pf_print_state(state);
1904                                 pf_print_flags(th->th_flags);
1905                                 printf("\n");
1906                         }
1907                         REASON_SET(reason, PFRES_TS);
1908                         return (PF_DROP);
1909                 }
1910         }
1911
1912         /*
1913          * We will note if a host sends his data packets with or without
1914          * timestamps.  And require all data packets to contain a timestamp
1915          * if the first does.  PAWS implicitly requires that all data packets be
1916          * timestamped.  But I think there are middle-man devices that hijack
1917          * TCP streams immediately after the 3whs and don't timestamp their
1918          * packets (seen in a WWW accelerator or cache).
1919          */
1920         if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags &
1921             (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) {
1922                 if (got_ts)
1923                         src->scrub->pfss_flags |= PFSS_DATA_TS;
1924                 else {
1925                         src->scrub->pfss_flags |= PFSS_DATA_NOTS;
1926                         if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub &&
1927                             (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) {
1928                                 /* Don't warn if other host rejected RFC1323 */
1929                                 DPFPRINTF(("Broken RFC1323 stack did not "
1930                                     "timestamp data packet. Disabled PAWS "
1931                                     "security.\n"));
1932                                 pf_print_state(state);
1933                                 pf_print_flags(th->th_flags);
1934                                 printf("\n");
1935                         }
1936                 }
1937         }
1938
1939         /*
1940          * Update PAWS values
1941          */
1942         if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags &
1943             (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) {
1944                 getmicrouptime(&src->scrub->pfss_last);
1945                 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) ||
1946                     (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1947                         src->scrub->pfss_tsval = tsval;
1948
1949                 if (tsecr) {
1950                         if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) ||
1951                             (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1952                                 src->scrub->pfss_tsecr = tsecr;
1953
1954                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 &&
1955                             (SEQ_LT(tsval, src->scrub->pfss_tsval0) ||
1956                             src->scrub->pfss_tsval0 == 0)) {
1957                                 /* tsval0 MUST be the lowest timestamp */
1958                                 src->scrub->pfss_tsval0 = tsval;
1959                         }
1960
1961                         /* Only fully initialized after a TS gets echoed */
1962                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0)
1963                                 src->scrub->pfss_flags |= PFSS_PAWS;
1964                 }
1965         }
1966
1967         /* I have a dream....  TCP segment reassembly.... */
1968         return (0);
1969 }
1970
1971 int
1972 pf_normalize_mss(struct mbuf *m, int off, struct pf_pdesc *pd)
1973 {
1974         struct tcphdr   *th = &pd->hdr.tcp;
1975         u_int16_t       *mss;
1976         int              thoff;
1977         int              opt, cnt, optlen = 0;
1978         u_char           opts[TCP_MAXOLEN];
1979         u_char          *optp = opts;
1980         size_t           startoff;
1981
1982         thoff = th->th_off << 2;
1983         cnt = thoff - sizeof(struct tcphdr);
1984
1985         if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt,
1986             NULL, NULL, pd->af))
1987                 return (0);
1988
1989         for (; cnt > 0; cnt -= optlen, optp += optlen) {
1990                 startoff = optp - opts;
1991                 opt = optp[0];
1992                 if (opt == TCPOPT_EOL)
1993                         break;
1994                 if (opt == TCPOPT_NOP)
1995                         optlen = 1;
1996                 else {
1997                         if (cnt < 2)
1998                                 break;
1999                         optlen = optp[1];
2000                         if (optlen < 2 || optlen > cnt)
2001                                 break;
2002                 }
2003                 switch (opt) {
2004                 case TCPOPT_MAXSEG:
2005                         mss = (u_int16_t *)(optp + 2);
2006                         if ((ntohs(*mss)) > pd->act.max_mss) {
2007                                 pf_patch_16_unaligned(m,
2008                                     &th->th_sum,
2009                                     mss, htons(pd->act.max_mss),
2010                                     PF_ALGNMNT(startoff),
2011                                     0);
2012                                 m_copyback(m, off + sizeof(*th),
2013                                     thoff - sizeof(*th), opts);
2014                                 m_copyback(m, off, sizeof(*th), (caddr_t)th);
2015                         }
2016                         break;
2017                 default:
2018                         break;
2019                 }
2020         }
2021
2022         return (0);
2023 }
2024
2025 static int
2026 pf_scan_sctp(struct mbuf *m, int ipoff, int off, struct pf_pdesc *pd)
2027 {
2028         struct sctp_chunkhdr ch = { };
2029         int chunk_off = sizeof(struct sctphdr);
2030         int chunk_start;
2031
2032         while (off + chunk_off < pd->tot_len) {
2033                 if (!pf_pull_hdr(m, off + chunk_off, &ch, sizeof(ch), NULL,
2034                     NULL, pd->af))
2035                         return (PF_DROP);
2036
2037                 /* Length includes the header, this must be at least 4. */
2038                 if (ntohs(ch.chunk_length) < 4)
2039                         return (PF_DROP);
2040
2041                 chunk_start = chunk_off;
2042                 chunk_off += roundup(ntohs(ch.chunk_length), 4);
2043
2044                 switch (ch.chunk_type) {
2045                 case SCTP_INITIATION: {
2046                         struct sctp_init_chunk init;
2047
2048                         if (!pf_pull_hdr(m, off + chunk_start, &init,
2049                             sizeof(init), NULL, NULL, pd->af))
2050                                 return (PF_DROP);
2051
2052                         /*
2053                          * RFC 9620, Section 3.3.2, "The Initiate Tag is allowed to have
2054                          * any value except 0."
2055                          */
2056                         if (init.init.initiate_tag == 0)
2057                                 return (PF_DROP);
2058                         if (init.init.num_inbound_streams == 0)
2059                                 return (PF_DROP);
2060                         if (init.init.num_outbound_streams == 0)
2061                                 return (PF_DROP);
2062                         if (ntohl(init.init.a_rwnd) < SCTP_MIN_RWND)
2063                                 return (PF_DROP);
2064
2065                         /*
2066                          * RFC 9260, Section 3.1, INIT chunks MUST have zero
2067                          * verification tag.
2068                          */
2069                         if (pd->hdr.sctp.v_tag != 0)
2070                                 return (PF_DROP);
2071
2072                         pd->sctp_initiate_tag = init.init.initiate_tag;
2073
2074                         pd->sctp_flags |= PFDESC_SCTP_INIT;
2075                         break;
2076                 }
2077                 case SCTP_INITIATION_ACK:
2078                         pd->sctp_flags |= PFDESC_SCTP_INIT_ACK;
2079                         break;
2080                 case SCTP_ABORT_ASSOCIATION:
2081                         pd->sctp_flags |= PFDESC_SCTP_ABORT;
2082                         break;
2083                 case SCTP_SHUTDOWN:
2084                 case SCTP_SHUTDOWN_ACK:
2085                         pd->sctp_flags |= PFDESC_SCTP_SHUTDOWN;
2086                         break;
2087                 case SCTP_SHUTDOWN_COMPLETE:
2088                         pd->sctp_flags |= PFDESC_SCTP_SHUTDOWN_COMPLETE;
2089                         break;
2090                 case SCTP_COOKIE_ECHO:
2091                 case SCTP_COOKIE_ACK:
2092                         pd->sctp_flags |= PFDESC_SCTP_COOKIE;
2093                         break;
2094                 case SCTP_DATA:
2095                         pd->sctp_flags |= PFDESC_SCTP_DATA;
2096                         break;
2097                 default:
2098                         pd->sctp_flags |= PFDESC_SCTP_OTHER;
2099                         break;
2100                 }
2101         }
2102
2103         /* Validate chunk lengths vs. packet length. */
2104         if (off + chunk_off != pd->tot_len)
2105                 return (PF_DROP);
2106
2107         /*
2108          * INIT, INIT_ACK or SHUTDOWN_COMPLETE chunks must always be the only
2109          * one in a packet.
2110          */
2111         if ((pd->sctp_flags & PFDESC_SCTP_INIT) &&
2112             (pd->sctp_flags & ~PFDESC_SCTP_INIT))
2113                 return (PF_DROP);
2114         if ((pd->sctp_flags & PFDESC_SCTP_INIT_ACK) &&
2115             (pd->sctp_flags & ~PFDESC_SCTP_INIT_ACK))
2116                 return (PF_DROP);
2117         if ((pd->sctp_flags & PFDESC_SCTP_SHUTDOWN_COMPLETE) &&
2118             (pd->sctp_flags & ~PFDESC_SCTP_SHUTDOWN_COMPLETE))
2119                 return (PF_DROP);
2120
2121         return (PF_PASS);
2122 }
2123
2124 int
2125 pf_normalize_sctp(int dir, struct pfi_kkif *kif, struct mbuf *m, int ipoff,
2126     int off, void *h, struct pf_pdesc *pd)
2127 {
2128         struct pf_krule *r, *rm = NULL;
2129         struct sctphdr  *sh = &pd->hdr.sctp;
2130         u_short          reason;
2131         sa_family_t      af = pd->af;
2132         int              srs;
2133
2134         PF_RULES_RASSERT();
2135
2136         /* Unconditionally scan the SCTP packet, because we need to look for
2137          * things like shutdown and asconf chunks. */
2138         if (pf_scan_sctp(m, ipoff, off, pd) != PF_PASS)
2139                 goto sctp_drop;
2140
2141         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
2142         /* Check if there any scrub rules. Lack of scrub rules means enforced
2143          * packet normalization operation just like in OpenBSD. */
2144         srs = (r != NULL);
2145         while (r != NULL) {
2146                 pf_counter_u64_add(&r->evaluations, 1);
2147                 if (pfi_kkif_match(r->kif, kif) == r->ifnot)
2148                         r = r->skip[PF_SKIP_IFP].ptr;
2149                 else if (r->direction && r->direction != dir)
2150                         r = r->skip[PF_SKIP_DIR].ptr;
2151                 else if (r->af && r->af != af)
2152                         r = r->skip[PF_SKIP_AF].ptr;
2153                 else if (r->proto && r->proto != pd->proto)
2154                         r = r->skip[PF_SKIP_PROTO].ptr;
2155                 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af,
2156                     r->src.neg, kif, M_GETFIB(m)))
2157                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
2158                 else if (r->src.port_op && !pf_match_port(r->src.port_op,
2159                             r->src.port[0], r->src.port[1], sh->src_port))
2160                         r = r->skip[PF_SKIP_SRC_PORT].ptr;
2161                 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af,
2162                     r->dst.neg, NULL, M_GETFIB(m)))
2163                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
2164                 else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
2165                             r->dst.port[0], r->dst.port[1], sh->dest_port))
2166                         r = r->skip[PF_SKIP_DST_PORT].ptr;
2167                 else {
2168                         rm = r;
2169                         break;
2170                 }
2171         }
2172
2173         if (srs) {
2174                 /* With scrub rules present SCTP normalization happens only
2175                  * if one of rules has matched and it's not a "no scrub" rule */
2176                 if (rm == NULL || rm->action == PF_NOSCRUB)
2177                         return (PF_PASS);
2178
2179                 pf_counter_u64_critical_enter();
2180                 pf_counter_u64_add_protected(&r->packets[dir == PF_OUT], 1);
2181                 pf_counter_u64_add_protected(&r->bytes[dir == PF_OUT], pd->tot_len);
2182                 pf_counter_u64_critical_exit();
2183         }
2184
2185         /* Verify we're a multiple of 4 bytes long */
2186         if ((pd->tot_len - off - sizeof(struct sctphdr)) % 4)
2187                 goto sctp_drop;
2188
2189         /* INIT chunk needs to be the only chunk */
2190         if (pd->sctp_flags & PFDESC_SCTP_INIT)
2191                 if (pd->sctp_flags & ~PFDESC_SCTP_INIT)
2192                         goto sctp_drop;
2193
2194         return (PF_PASS);
2195
2196 sctp_drop:
2197         REASON_SET(&reason, PFRES_NORM);
2198         if (rm != NULL && r->log)
2199                 PFLOG_PACKET(kif, m, AF_INET, reason, r, NULL, NULL, pd,
2200                     1);
2201
2202         return (PF_DROP);
2203 }
2204
2205 #ifdef INET
2206 void
2207 pf_scrub_ip(struct mbuf **m0, struct pf_pdesc *pd)
2208 {
2209         struct mbuf             *m = *m0;
2210         struct ip               *h = mtod(m, struct ip *);
2211
2212         /* Clear IP_DF if no-df was requested */
2213         if (pd->act.flags & PFSTATE_NODF && h->ip_off & htons(IP_DF)) {
2214                 u_int16_t ip_off = h->ip_off;
2215
2216                 h->ip_off &= htons(~IP_DF);
2217                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
2218         }
2219
2220         /* Enforce a minimum ttl, may cause endless packet loops */
2221         if (pd->act.min_ttl && h->ip_ttl < pd->act.min_ttl) {
2222                 u_int16_t ip_ttl = h->ip_ttl;
2223
2224                 h->ip_ttl = pd->act.min_ttl;
2225                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
2226         }
2227
2228         /* Enforce tos */
2229         if (pd->act.flags & PFSTATE_SETTOS) {
2230                 u_int16_t       ov, nv;
2231
2232                 ov = *(u_int16_t *)h;
2233                 h->ip_tos = pd->act.set_tos | (h->ip_tos & IPTOS_ECN_MASK);
2234                 nv = *(u_int16_t *)h;
2235
2236                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0);
2237         }
2238
2239         /* random-id, but not for fragments */
2240         if (pd->act.flags & PFSTATE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) {
2241                 uint16_t ip_id = h->ip_id;
2242
2243                 ip_fillid(h);
2244                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0);
2245         }
2246 }
2247 #endif /* INET */
2248
2249 #ifdef INET6
2250 void
2251 pf_scrub_ip6(struct mbuf **m0, struct pf_pdesc *pd)
2252 {
2253         struct mbuf             *m = *m0;
2254         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
2255
2256         /* Enforce a minimum ttl, may cause endless packet loops */
2257         if (pd->act.min_ttl && h->ip6_hlim < pd->act.min_ttl)
2258                 h->ip6_hlim = pd->act.min_ttl;
2259
2260         /* Enforce tos. Set traffic class bits */
2261         if (pd->act.flags & PFSTATE_SETTOS) {
2262                 h->ip6_flow &= IPV6_FLOWLABEL_MASK | IPV6_VERSION_MASK;
2263                 h->ip6_flow |= htonl((pd->act.set_tos | IPV6_ECN(h)) << 20);
2264         }
2265 }
2266 #endif