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 <netinet/tcp.h>
  56 #include <netinet/tcp_fsm.h>
  57 #include <netinet/tcp_seq.h>
  58
  59 #ifdef INET6
  60 #include <netinet/ip6.h>
  61 #endif /* INET6 */
  62
  63 struct pf_frent {
  64         TAILQ_ENTRY(pf_frent)   fr_next;
  65         struct mbuf     *fe_m;
  66         uint16_t        fe_hdrlen;      /* ipv4 header length with ip options
  67                                            ipv6, extension, fragment header */
  68         uint16_t        fe_extoff;      /* last extension header offset or 0 */
  69         uint16_t        fe_len;         /* fragment length */
  70         uint16_t        fe_off;         /* fragment offset */
  71         uint16_t        fe_mff;         /* more fragment flag */
  72 };
  73
  74 struct pf_fragment_cmp {
  75         struct pf_addr  frc_src;
  76         struct pf_addr  frc_dst;
  77         uint32_t        frc_id;
  78         sa_family_t     frc_af;
  79         uint8_t         frc_proto;
  80 };
  81
  82 struct pf_fragment {
  83         struct pf_fragment_cmp  fr_key;
  84 #define fr_src  fr_key.frc_src
  85 #define fr_dst  fr_key.frc_dst
  86 #define fr_id   fr_key.frc_id
  87 #define fr_af   fr_key.frc_af
  88 #define fr_proto        fr_key.frc_proto
  89
  90         /* pointers to queue element */
  91         struct pf_frent *fr_firstoff[PF_FRAG_ENTRY_POINTS];
  92         /* count entries between pointers */
  93         uint8_t fr_entries[PF_FRAG_ENTRY_POINTS];
  94         RB_ENTRY(pf_fragment) fr_entry;
  95         TAILQ_ENTRY(pf_fragment) frag_next;
  96         uint32_t        fr_timeout;
  97         uint16_t        fr_maxlen;      /* maximum length of single fragment */
  98         u_int16_t       fr_holes;       /* number of holes in the queue */
  99         TAILQ_HEAD(pf_fragq, pf_frent) fr_queue;
 100 };
 101
 102 struct pf_fragment_tag {
 103         uint16_t        ft_hdrlen;      /* header length of reassembled pkt */
 104         uint16_t        ft_extoff;      /* last extension header offset or 0 */
 105         uint16_t        ft_maxlen;      /* maximum fragment payload length */
 106         uint32_t        ft_id;          /* fragment id */
 107 };
 108
 109 static struct mtx pf_frag_mtx;
 110 MTX_SYSINIT(pf_frag_mtx, &pf_frag_mtx, "pf fragments", MTX_DEF);
 111 #define PF_FRAG_LOCK()          mtx_lock(&pf_frag_mtx)
 112 #define PF_FRAG_UNLOCK()        mtx_unlock(&pf_frag_mtx)
 113 #define PF_FRAG_ASSERT()        mtx_assert(&pf_frag_mtx, MA_OWNED)
 114
 115 VNET_DEFINE(uma_zone_t, pf_state_scrub_z);      /* XXX: shared with pfsync */
 116
 117 VNET_DEFINE_STATIC(uma_zone_t, pf_frent_z);
 118 #define V_pf_frent_z    VNET(pf_frent_z)
 119 VNET_DEFINE_STATIC(uma_zone_t, pf_frag_z);
 120 #define V_pf_frag_z     VNET(pf_frag_z)
 121
 122 TAILQ_HEAD(pf_fragqueue, pf_fragment);
 123 TAILQ_HEAD(pf_cachequeue, pf_fragment);
 124 VNET_DEFINE_STATIC(struct pf_fragqueue, pf_fragqueue);
 125 #define V_pf_fragqueue                  VNET(pf_fragqueue)
 126 RB_HEAD(pf_frag_tree, pf_fragment);
 127 VNET_DEFINE_STATIC(struct pf_frag_tree, pf_frag_tree);
 128 #define V_pf_frag_tree                  VNET(pf_frag_tree)
 129 static int               pf_frag_compare(struct pf_fragment *,
 130                             struct pf_fragment *);
 131 static RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 132 static RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 133
 134 static void     pf_flush_fragments(void);
 135 static void     pf_free_fragment(struct pf_fragment *);
 136 static void     pf_remove_fragment(struct pf_fragment *);
 137 static int      pf_normalize_tcpopt(struct pf_rule *, struct mbuf *,
 138                     struct tcphdr *, int, sa_family_t);
 139 static struct pf_frent *pf_create_fragment(u_short *);
 140 static int      pf_frent_holes(struct pf_frent *frent);
 141 static struct pf_fragment *pf_find_fragment(struct pf_fragment_cmp *key,
 142                     struct pf_frag_tree *tree);
 143 static inline int       pf_frent_index(struct pf_frent *);
 144 static int      pf_frent_insert(struct pf_fragment *,
 145                             struct pf_frent *, struct pf_frent *);
 146 void                    pf_frent_remove(struct pf_fragment *,
 147                             struct pf_frent *);
 148 struct pf_frent         *pf_frent_previous(struct pf_fragment *,
 149                             struct pf_frent *);
 150 static struct pf_fragment *pf_fillup_fragment(struct pf_fragment_cmp *,
 151                     struct pf_frent *, u_short *);
 152 static struct mbuf *pf_join_fragment(struct pf_fragment *);
 153 #ifdef INET
 154 static void     pf_scrub_ip(struct mbuf **, uint32_t, uint8_t, uint8_t);
 155 static int      pf_reassemble(struct mbuf **, struct ip *, int, u_short *);
 156 #endif  /* INET */
 157 #ifdef INET6
 158 static int      pf_reassemble6(struct mbuf **, struct ip6_hdr *,
 159                     struct ip6_frag *, uint16_t, uint16_t, u_short *);
 160 static void     pf_scrub_ip6(struct mbuf **, uint8_t);
 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         V_pf_limits[PF_LIMIT_FRAGS].zone = V_pf_frent_z;
 196         V_pf_limits[PF_LIMIT_FRAGS].limit = PFFRAG_FRENT_HIWAT;
 197         uma_zone_set_max(V_pf_frent_z, PFFRAG_FRENT_HIWAT);
 198         uma_zone_set_warning(V_pf_frent_z, "PF frag entries limit reached");
 199
 200         TAILQ_INIT(&V_pf_fragqueue);
 201 }
 202
 203 void
 204 pf_normalize_cleanup(void)
 205 {
 206
 207         uma_zdestroy(V_pf_state_scrub_z);
 208         uma_zdestroy(V_pf_frent_z);
 209         uma_zdestroy(V_pf_frag_z);
 210 }
 211
 212 static int
 213 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b)
 214 {
 215         int     diff;
 216
 217         if ((diff = a->fr_id - b->fr_id) != 0)
 218                 return (diff);
 219         if ((diff = a->fr_proto - b->fr_proto) != 0)
 220                 return (diff);
 221         if ((diff = a->fr_af - b->fr_af) != 0)
 222                 return (diff);
 223         if ((diff = pf_addr_cmp(&a->fr_src, &b->fr_src, a->fr_af)) != 0)
 224                 return (diff);
 225         if ((diff = pf_addr_cmp(&a->fr_dst, &b->fr_dst, a->fr_af)) != 0)
 226                 return (diff);
 227         return (0);
 228 }
 229
 230 void
 231 pf_purge_expired_fragments(void)
 232 {
 233         u_int32_t       expire = time_uptime -
 234                             V_pf_default_rule.timeout[PFTM_FRAG];
 235
 236         pf_purge_fragments(expire);
 237 }
 238
 239 void
 240 pf_purge_fragments(uint32_t expire)
 241 {
 242         struct pf_fragment      *frag;
 243
 244         PF_FRAG_LOCK();
 245         while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) {
 246                 if (frag->fr_timeout > expire)
 247                         break;
 248
 249                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 250                 pf_free_fragment(frag);
 251         }
 252
 253         PF_FRAG_UNLOCK();
 254 }
 255
 256 /*
 257  * Try to flush old fragments to make space for new ones
 258  */
 259 static void
 260 pf_flush_fragments(void)
 261 {
 262         struct pf_fragment      *frag;
 263         int                      goal;
 264
 265         PF_FRAG_ASSERT();
 266
 267         goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10;
 268         DPFPRINTF(("trying to free %d frag entriess\n", goal));
 269         while (goal < uma_zone_get_cur(V_pf_frent_z)) {
 270                 frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue);
 271                 if (frag)
 272                         pf_free_fragment(frag);
 273                 else
 274                         break;
 275         }
 276 }
 277
 278 /* Frees the fragments and all associated entries */
 279 static void
 280 pf_free_fragment(struct pf_fragment *frag)
 281 {
 282         struct pf_frent         *frent;
 283
 284         PF_FRAG_ASSERT();
 285
 286         /* Free all fragments */
 287         for (frent = TAILQ_FIRST(&frag->fr_queue); frent;
 288             frent = TAILQ_FIRST(&frag->fr_queue)) {
 289                 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
 290
 291                 m_freem(frent->fe_m);
 292                 uma_zfree(V_pf_frent_z, frent);
 293         }
 294
 295         pf_remove_fragment(frag);
 296 }
 297
 298 static struct pf_fragment *
 299 pf_find_fragment(struct pf_fragment_cmp *key, struct pf_frag_tree *tree)
 300 {
 301         struct pf_fragment      *frag;
 302
 303         PF_FRAG_ASSERT();
 304
 305         frag = RB_FIND(pf_frag_tree, tree, (struct pf_fragment *)key);
 306         if (frag != NULL) {
 307                 /* XXX Are we sure we want to update the timeout? */
 308                 frag->fr_timeout = time_uptime;
 309                 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 310                 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
 311         }
 312
 313         return (frag);
 314 }
 315
 316 /* Removes a fragment from the fragment queue and frees the fragment */
 317 static void
 318 pf_remove_fragment(struct pf_fragment *frag)
 319 {
 320
 321         PF_FRAG_ASSERT();
 322         KASSERT(frag, ("frag != NULL"));
 323
 324         RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag);
 325         TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 326         uma_zfree(V_pf_frag_z, frag);
 327 }
 328
 329 static struct pf_frent *
 330 pf_create_fragment(u_short *reason)
 331 {
 332         struct pf_frent *frent;
 333
 334         PF_FRAG_ASSERT();
 335
 336         frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 337         if (frent == NULL) {
 338                 pf_flush_fragments();
 339                 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 340                 if (frent == NULL) {
 341                         REASON_SET(reason, PFRES_MEMORY);
 342                         return (NULL);
 343                 }
 344         }
 345
 346         return (frent);
 347 }
 348
 349 /*
 350  * Calculate the additional holes that were created in the fragment
 351  * queue by inserting this fragment.  A fragment in the middle
 352  * creates one more hole by splitting.  For each connected side,
 353  * it loses one hole.
 354  * Fragment entry must be in the queue when calling this function.
 355  */
 356 static int
 357 pf_frent_holes(struct pf_frent *frent)
 358 {
 359         struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next);
 360         struct pf_frent *next = TAILQ_NEXT(frent, fr_next);
 361         int holes = 1;
 362
 363         if (prev == NULL) {
 364                 if (frent->fe_off == 0)
 365                         holes--;
 366         } else {
 367                 KASSERT(frent->fe_off != 0, ("frent->fe_off != 0"));
 368                 if (frent->fe_off == prev->fe_off + prev->fe_len)
 369                         holes--;
 370         }
 371         if (next == NULL) {
 372                 if (!frent->fe_mff)
 373                         holes--;
 374         } else {
 375                 KASSERT(frent->fe_mff, ("frent->fe_mff"));
 376                 if (next->fe_off == frent->fe_off + frent->fe_len)
 377                         holes--;
 378         }
 379         return holes;
 380 }
 381
 382 static inline int
 383 pf_frent_index(struct pf_frent *frent)
 384 {
 385         /*
 386          * We have an array of 16 entry points to the queue.  A full size
 387          * 65535 octet IP packet can have 8192 fragments.  So the queue
 388          * traversal length is at most 512 and at most 16 entry points are
 389          * checked.  We need 128 additional bytes on a 64 bit architecture.
 390          */
 391         CTASSERT(((u_int16_t)0xffff &~ 7) / (0x10000 / PF_FRAG_ENTRY_POINTS) ==
 392             16 - 1);
 393         CTASSERT(((u_int16_t)0xffff >> 3) / PF_FRAG_ENTRY_POINTS == 512 - 1);
 394
 395         return frent->fe_off / (0x10000 / PF_FRAG_ENTRY_POINTS);
 396 }
 397
 398 static int
 399 pf_frent_insert(struct pf_fragment *frag, struct pf_frent *frent,
 400     struct pf_frent *prev)
 401 {
 402         int index;
 403
 404         CTASSERT(PF_FRAG_ENTRY_LIMIT <= 0xff);
 405
 406         /*
 407          * A packet has at most 65536 octets.  With 16 entry points, each one
 408          * spawns 4096 octets.  We limit these to 64 fragments each, which
 409          * means on average every fragment must have at least 64 octets.
 410          */
 411         index = pf_frent_index(frent);
 412         if (frag->fr_entries[index] >= PF_FRAG_ENTRY_LIMIT)
 413                 return ENOBUFS;
 414         frag->fr_entries[index]++;
 415
 416         if (prev == NULL) {
 417                 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next);
 418         } else {
 419                 KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off,
 420                     ("overlapping fragment"));
 421                 TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next);
 422         }
 423
 424         if (frag->fr_firstoff[index] == NULL) {
 425                 KASSERT(prev == NULL || pf_frent_index(prev) < index,
 426                     ("prev == NULL || pf_frent_index(pref) < index"));
 427                 frag->fr_firstoff[index] = frent;
 428         } else {
 429                 if (frent->fe_off < frag->fr_firstoff[index]->fe_off) {
 430                         KASSERT(prev == NULL || pf_frent_index(prev) < index,
 431                             ("prev == NULL || pf_frent_index(pref) < index"));
 432                         frag->fr_firstoff[index] = frent;
 433                 } else {
 434                         KASSERT(prev != NULL, ("prev != NULL"));
 435                         KASSERT(pf_frent_index(prev) == index,
 436                             ("pf_frent_index(prev) == index"));
 437                 }
 438         }
 439
 440         frag->fr_holes += pf_frent_holes(frent);
 441
 442         return 0;
 443 }
 444
 445 void
 446 pf_frent_remove(struct pf_fragment *frag, struct pf_frent *frent)
 447 {
 448 #ifdef INVARIANTS
 449         struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next);
 450 #endif
 451         struct pf_frent *next = TAILQ_NEXT(frent, fr_next);
 452         int index;
 453
 454         frag->fr_holes -= pf_frent_holes(frent);
 455
 456         index = pf_frent_index(frent);
 457         KASSERT(frag->fr_firstoff[index] != NULL, ("frent not found"));
 458         if (frag->fr_firstoff[index]->fe_off == frent->fe_off) {
 459                 if (next == NULL) {
 460                         frag->fr_firstoff[index] = NULL;
 461                 } else {
 462                         KASSERT(frent->fe_off + frent->fe_len <= next->fe_off,
 463                             ("overlapping fragment"));
 464                         if (pf_frent_index(next) == index) {
 465                                 frag->fr_firstoff[index] = next;
 466                         } else {
 467                                 frag->fr_firstoff[index] = NULL;
 468                         }
 469                 }
 470         } else {
 471                 KASSERT(frag->fr_firstoff[index]->fe_off < frent->fe_off,
 472                     ("frag->fr_firstoff[index]->fe_off < frent->fe_off"));
 473                 KASSERT(prev != NULL, ("prev != NULL"));
 474                 KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off,
 475                     ("overlapping fragment"));
 476                 KASSERT(pf_frent_index(prev) == index,
 477                     ("pf_frent_index(prev) == index"));
 478         }
 479
 480         TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
 481
 482         KASSERT(frag->fr_entries[index] > 0, ("No fragments remaining"));
 483         frag->fr_entries[index]--;
 484 }
 485
 486 struct pf_frent *
 487 pf_frent_previous(struct pf_fragment *frag, struct pf_frent *frent)
 488 {
 489         struct pf_frent *prev, *next;
 490         int index;
 491
 492         /*
 493          * If there are no fragments after frag, take the final one.  Assume
 494          * that the global queue is not empty.
 495          */
 496         prev = TAILQ_LAST(&frag->fr_queue, pf_fragq);
 497         KASSERT(prev != NULL, ("prev != NULL"));
 498         if (prev->fe_off <= frent->fe_off)
 499                 return prev;
 500         /*
 501          * We want to find a fragment entry that is before frag, but still
 502          * close to it.  Find the first fragment entry that is in the same
 503          * entry point or in the first entry point after that.  As we have
 504          * already checked that there are entries behind frag, this will
 505          * succeed.
 506          */
 507         for (index = pf_frent_index(frent); index < PF_FRAG_ENTRY_POINTS;
 508             index++) {
 509                 prev = frag->fr_firstoff[index];
 510                 if (prev != NULL)
 511                         break;
 512         }
 513         KASSERT(prev != NULL, ("prev != NULL"));
 514         /*
 515          * In prev we may have a fragment from the same entry point that is
 516          * before frent, or one that is just one position behind frent.
 517          * In the latter case, we go back one step and have the predecessor.
 518          * There may be none if the new fragment will be the first one.
 519          */
 520         if (prev->fe_off > frent->fe_off) {
 521                 prev = TAILQ_PREV(prev, pf_fragq, fr_next);
 522                 if (prev == NULL)
 523                         return NULL;
 524                 KASSERT(prev->fe_off <= frent->fe_off,
 525                     ("prev->fe_off <= frent->fe_off"));
 526                 return prev;
 527         }
 528         /*
 529          * In prev is the first fragment of the entry point.  The offset
 530          * of frag is behind it.  Find the closest previous fragment.
 531          */
 532         for (next = TAILQ_NEXT(prev, fr_next); next != NULL;
 533             next = TAILQ_NEXT(next, fr_next)) {
 534                 if (next->fe_off > frent->fe_off)
 535                         break;
 536                 prev = next;
 537         }
 538         return prev;
 539 }
 540
 541 static struct pf_fragment *
 542 pf_fillup_fragment(struct pf_fragment_cmp *key, struct pf_frent *frent,
 543     u_short *reason)
 544 {
 545         struct pf_frent         *after, *next, *prev;
 546         struct pf_fragment      *frag;
 547         uint16_t                total;
 548
 549         PF_FRAG_ASSERT();
 550
 551         /* No empty fragments. */
 552         if (frent->fe_len == 0) {
 553                 DPFPRINTF(("bad fragment: len 0\n"));
 554                 goto bad_fragment;
 555         }
 556
 557         /* All fragments are 8 byte aligned. */
 558         if (frent->fe_mff && (frent->fe_len & 0x7)) {
 559                 DPFPRINTF(("bad fragment: mff and len %d\n", frent->fe_len));
 560                 goto bad_fragment;
 561         }
 562
 563         /* Respect maximum length, IP_MAXPACKET == IPV6_MAXPACKET. */
 564         if (frent->fe_off + frent->fe_len > IP_MAXPACKET) {
 565                 DPFPRINTF(("bad fragment: max packet %d\n",
 566                     frent->fe_off + frent->fe_len));
 567                 goto bad_fragment;
 568         }
 569
 570         DPFPRINTF((key->frc_af == AF_INET ?
 571             "reass frag %d @ %d-%d\n" : "reass frag %#08x @ %d-%d\n",
 572             key->frc_id, frent->fe_off, frent->fe_off + frent->fe_len));
 573
 574         /* Fully buffer all of the fragments in this fragment queue. */
 575         frag = pf_find_fragment(key, &V_pf_frag_tree);
 576
 577         /* Create a new reassembly queue for this packet. */
 578         if (frag == NULL) {
 579                 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 580                 if (frag == NULL) {
 581                         pf_flush_fragments();
 582                         frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 583                         if (frag == NULL) {
 584                                 REASON_SET(reason, PFRES_MEMORY);
 585                                 goto drop_fragment;
 586                         }
 587                 }
 588
 589                 *(struct pf_fragment_cmp *)frag = *key;
 590                 memset(frag->fr_firstoff, 0, sizeof(frag->fr_firstoff));
 591                 memset(frag->fr_entries, 0, sizeof(frag->fr_entries));
 592                 frag->fr_timeout = time_uptime;
 593                 frag->fr_maxlen = frent->fe_len;
 594                 frag->fr_holes = 1;
 595                 TAILQ_INIT(&frag->fr_queue);
 596
 597                 RB_INSERT(pf_frag_tree, &V_pf_frag_tree, frag);
 598                 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
 599
 600                 /* We do not have a previous fragment, cannot fail. */
 601                 pf_frent_insert(frag, frent, NULL);
 602
 603                 return (frag);
 604         }
 605
 606         KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue"));
 607
 608         /* Remember maximum fragment len for refragmentation. */
 609         if (frent->fe_len > frag->fr_maxlen)
 610                 frag->fr_maxlen = frent->fe_len;
 611
 612         /* Maximum data we have seen already. */
 613         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 614                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 615
 616         /* Non terminal fragments must have more fragments flag. */
 617         if (frent->fe_off + frent->fe_len < total && !frent->fe_mff)
 618                 goto bad_fragment;
 619
 620         /* Check if we saw the last fragment already. */
 621         if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) {
 622                 if (frent->fe_off + frent->fe_len > total ||
 623                     (frent->fe_off + frent->fe_len == total && frent->fe_mff))
 624                         goto bad_fragment;
 625         } else {
 626                 if (frent->fe_off + frent->fe_len == total && !frent->fe_mff)
 627                         goto bad_fragment;
 628         }
 629
 630         /* Find neighbors for newly inserted fragment */
 631         prev = pf_frent_previous(frag, frent);
 632         if (prev == NULL) {
 633                 after = TAILQ_FIRST(&frag->fr_queue);
 634                 KASSERT(after != NULL, ("after != NULL"));
 635         } else {
 636                 after = TAILQ_NEXT(prev, fr_next);
 637         }
 638
 639         if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) {
 640                 uint16_t precut;
 641
 642                 precut = prev->fe_off + prev->fe_len - frent->fe_off;
 643                 if (precut >= frent->fe_len)
 644                         goto bad_fragment;
 645                 DPFPRINTF(("overlap -%d\n", precut));
 646                 m_adj(frent->fe_m, precut);
 647                 frent->fe_off += precut;
 648                 frent->fe_len -= precut;
 649         }
 650
 651         for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off;
 652             after = next) {
 653                 uint16_t aftercut;
 654
 655                 aftercut = frent->fe_off + frent->fe_len - after->fe_off;
 656                 DPFPRINTF(("adjust overlap %d\n", aftercut));
 657                 if (aftercut < after->fe_len) {
 658                         m_adj(after->fe_m, aftercut);
 659                         after->fe_off += aftercut;
 660                         after->fe_len -= aftercut;
 661                         break;
 662                 }
 663
 664                 /* This fragment is completely overlapped, lose it. */
 665                 next = TAILQ_NEXT(after, fr_next);
 666                 pf_frent_remove(frag, after);
 667                 m_freem(after->fe_m);
 668                 uma_zfree(V_pf_frent_z, after);
 669         }
 670
 671         /* If part of the queue gets too long, there is not way to recover. */
 672         if (pf_frent_insert(frag, frent, prev)) {
 673                 DPFPRINTF(("fragment queue limit exceeded\n"));
 674                 goto bad_fragment;
 675         }
 676
 677         return (frag);
 678
 679 bad_fragment:
 680         REASON_SET(reason, PFRES_FRAG);
 681 drop_fragment:
 682         uma_zfree(V_pf_frent_z, frent);
 683         return (NULL);
 684 }
 685
 686 static struct mbuf *
 687 pf_join_fragment(struct pf_fragment *frag)
 688 {
 689         struct mbuf *m, *m2;
 690         struct pf_frent *frent, *next;
 691
 692         frent = TAILQ_FIRST(&frag->fr_queue);
 693         next = TAILQ_NEXT(frent, fr_next);
 694
 695         m = frent->fe_m;
 696         m_adj(m, (frent->fe_hdrlen + frent->fe_len) - m->m_pkthdr.len);
 697         uma_zfree(V_pf_frent_z, frent);
 698         for (frent = next; frent != NULL; frent = next) {
 699                 next = TAILQ_NEXT(frent, fr_next);
 700
 701                 m2 = frent->fe_m;
 702                 /* Strip off ip header. */
 703                 m_adj(m2, frent->fe_hdrlen);
 704                 /* Strip off any trailing bytes. */
 705                 m_adj(m2, frent->fe_len - m2->m_pkthdr.len);
 706
 707                 uma_zfree(V_pf_frent_z, frent);
 708                 m_cat(m, m2);
 709         }
 710
 711         /* Remove from fragment queue. */
 712         pf_remove_fragment(frag);
 713
 714         return (m);
 715 }
 716
 717 #ifdef INET
 718 static int
 719 pf_reassemble(struct mbuf **m0, struct ip *ip, int dir, u_short *reason)
 720 {
 721         struct mbuf             *m = *m0;
 722         struct pf_frent         *frent;
 723         struct pf_fragment      *frag;
 724         struct pf_fragment_cmp  key;
 725         uint16_t                total, hdrlen;
 726
 727         /* Get an entry for the fragment queue */
 728         if ((frent = pf_create_fragment(reason)) == NULL)
 729                 return (PF_DROP);
 730
 731         frent->fe_m = m;
 732         frent->fe_hdrlen = ip->ip_hl << 2;
 733         frent->fe_extoff = 0;
 734         frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2);
 735         frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3;
 736         frent->fe_mff = ntohs(ip->ip_off) & IP_MF;
 737
 738         pf_ip2key(ip, dir, &key);
 739
 740         if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL)
 741                 return (PF_DROP);
 742
 743         /* The mbuf is part of the fragment entry, no direct free or access */
 744         m = *m0 = NULL;
 745
 746         if (frag->fr_holes) {
 747                 DPFPRINTF(("frag %d, holes %d\n", frag->fr_id, frag->fr_holes));
 748                 return (PF_PASS);  /* drop because *m0 is NULL, no error */
 749         }
 750
 751         /* We have all the data */
 752         frent = TAILQ_FIRST(&frag->fr_queue);
 753         KASSERT(frent != NULL, ("frent != NULL"));
 754         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 755                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 756         hdrlen = frent->fe_hdrlen;
 757
 758         m = *m0 = pf_join_fragment(frag);
 759         frag = NULL;
 760
 761         if (m->m_flags & M_PKTHDR) {
 762                 int plen = 0;
 763                 for (m = *m0; m; m = m->m_next)
 764                         plen += m->m_len;
 765                 m = *m0;
 766                 m->m_pkthdr.len = plen;
 767         }
 768
 769         ip = mtod(m, struct ip *);
 770         ip->ip_len = htons(hdrlen + total);
 771         ip->ip_off &= ~(IP_MF|IP_OFFMASK);
 772
 773         if (hdrlen + total > IP_MAXPACKET) {
 774                 DPFPRINTF(("drop: too big: %d\n", total));
 775                 ip->ip_len = 0;
 776                 REASON_SET(reason, PFRES_SHORT);
 777                 /* PF_DROP requires a valid mbuf *m0 in pf_test() */
 778                 return (PF_DROP);
 779         }
 780
 781         DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len)));
 782         return (PF_PASS);
 783 }
 784 #endif  /* INET */
 785
 786 #ifdef INET6
 787 static int
 788 pf_reassemble6(struct mbuf **m0, struct ip6_hdr *ip6, struct ip6_frag *fraghdr,
 789     uint16_t hdrlen, uint16_t extoff, u_short *reason)
 790 {
 791         struct mbuf             *m = *m0;
 792         struct pf_frent         *frent;
 793         struct pf_fragment      *frag;
 794         struct pf_fragment_cmp   key;
 795         struct m_tag            *mtag;
 796         struct pf_fragment_tag  *ftag;
 797         int                      off;
 798         uint32_t                 frag_id;
 799         uint16_t                 total, maxlen;
 800         uint8_t                  proto;
 801
 802         PF_FRAG_LOCK();
 803
 804         /* Get an entry for the fragment queue. */
 805         if ((frent = pf_create_fragment(reason)) == NULL) {
 806                 PF_FRAG_UNLOCK();
 807                 return (PF_DROP);
 808         }
 809
 810         frent->fe_m = m;
 811         frent->fe_hdrlen = hdrlen;
 812         frent->fe_extoff = extoff;
 813         frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen;
 814         frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK);
 815         frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG;
 816
 817         key.frc_src.v6 = ip6->ip6_src;
 818         key.frc_dst.v6 = ip6->ip6_dst;
 819         key.frc_af = AF_INET6;
 820         /* Only the first fragment's protocol is relevant. */
 821         key.frc_proto = 0;
 822         key.frc_id = fraghdr->ip6f_ident;
 823
 824         if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) {
 825                 PF_FRAG_UNLOCK();
 826                 return (PF_DROP);
 827         }
 828
 829         /* The mbuf is part of the fragment entry, no direct free or access. */
 830         m = *m0 = NULL;
 831
 832         if (frag->fr_holes) {
 833                 DPFPRINTF(("frag %d, holes %d\n", frag->fr_id,
 834                     frag->fr_holes));
 835                 PF_FRAG_UNLOCK();
 836                 return (PF_PASS);  /* Drop because *m0 is NULL, no error. */
 837         }
 838
 839         /* We have all the data. */
 840         frent = TAILQ_FIRST(&frag->fr_queue);
 841         KASSERT(frent != NULL, ("frent != NULL"));
 842         extoff = frent->fe_extoff;
 843         maxlen = frag->fr_maxlen;
 844         frag_id = frag->fr_id;
 845         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 846                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 847         hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag);
 848
 849         m = *m0 = pf_join_fragment(frag);
 850         frag = NULL;
 851
 852         PF_FRAG_UNLOCK();
 853
 854         /* Take protocol from first fragment header. */
 855         m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off);
 856         KASSERT(m, ("%s: short mbuf chain", __func__));
 857         proto = *(mtod(m, caddr_t) + off);
 858         m = *m0;
 859
 860         /* Delete frag6 header */
 861         if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0)
 862                 goto fail;
 863
 864         if (m->m_flags & M_PKTHDR) {
 865                 int plen = 0;
 866                 for (m = *m0; m; m = m->m_next)
 867                         plen += m->m_len;
 868                 m = *m0;
 869                 m->m_pkthdr.len = plen;
 870         }
 871
 872         if ((mtag = m_tag_get(PF_REASSEMBLED, sizeof(struct pf_fragment_tag),
 873             M_NOWAIT)) == NULL)
 874                 goto fail;
 875         ftag = (struct pf_fragment_tag *)(mtag + 1);
 876         ftag->ft_hdrlen = hdrlen;
 877         ftag->ft_extoff = extoff;
 878         ftag->ft_maxlen = maxlen;
 879         ftag->ft_id = frag_id;
 880         m_tag_prepend(m, mtag);
 881
 882         ip6 = mtod(m, struct ip6_hdr *);
 883         ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total);
 884         if (extoff) {
 885                 /* Write protocol into next field of last extension header. */
 886                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
 887                     &off);
 888                 KASSERT(m, ("%s: short mbuf chain", __func__));
 889                 *(mtod(m, char *) + off) = proto;
 890                 m = *m0;
 891         } else
 892                 ip6->ip6_nxt = proto;
 893
 894         if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) {
 895                 DPFPRINTF(("drop: too big: %d\n", total));
 896                 ip6->ip6_plen = 0;
 897                 REASON_SET(reason, PFRES_SHORT);
 898                 /* PF_DROP requires a valid mbuf *m0 in pf_test6(). */
 899                 return (PF_DROP);
 900         }
 901
 902         DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip6->ip6_plen)));
 903         return (PF_PASS);
 904
 905 fail:
 906         REASON_SET(reason, PFRES_MEMORY);
 907         /* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */
 908         return (PF_DROP);
 909 }
 910 #endif  /* INET6 */
 911
 912 #ifdef INET6
 913 int
 914 pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag)
 915 {
 916         struct mbuf             *m = *m0, *t;
 917         struct pf_fragment_tag  *ftag = (struct pf_fragment_tag *)(mtag + 1);
 918         struct pf_pdesc          pd;
 919         uint32_t                 frag_id;
 920         uint16_t                 hdrlen, extoff, maxlen;
 921         uint8_t                  proto;
 922         int                      error, action;
 923
 924         hdrlen = ftag->ft_hdrlen;
 925         extoff = ftag->ft_extoff;
 926         maxlen = ftag->ft_maxlen;
 927         frag_id = ftag->ft_id;
 928         m_tag_delete(m, mtag);
 929         mtag = NULL;
 930         ftag = NULL;
 931
 932         if (extoff) {
 933                 int off;
 934
 935                 /* Use protocol from next field of last extension header */
 936                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
 937                     &off);
 938                 KASSERT((m != NULL), ("pf_refragment6: short mbuf chain"));
 939                 proto = *(mtod(m, caddr_t) + off);
 940                 *(mtod(m, char *) + off) = IPPROTO_FRAGMENT;
 941                 m = *m0;
 942         } else {
 943                 struct ip6_hdr *hdr;
 944
 945                 hdr = mtod(m, struct ip6_hdr *);
 946                 proto = hdr->ip6_nxt;
 947                 hdr->ip6_nxt = IPPROTO_FRAGMENT;
 948         }
 949
 950         /* The MTU must be a multiple of 8 bytes, or we risk doing the
 951          * fragmentation wrong. */
 952         maxlen = maxlen & ~7;
 953
 954         /*
 955          * Maxlen may be less than 8 if there was only a single
 956          * fragment.  As it was fragmented before, add a fragment
 957          * header also for a single fragment.  If total or maxlen
 958          * is less than 8, ip6_fragment() will return EMSGSIZE and
 959          * we drop the packet.
 960          */
 961         error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id);
 962         m = (*m0)->m_nextpkt;
 963         (*m0)->m_nextpkt = NULL;
 964         if (error == 0) {
 965                 /* The first mbuf contains the unfragmented packet. */
 966                 m_freem(*m0);
 967                 *m0 = NULL;
 968                 action = PF_PASS;
 969         } else {
 970                 /* Drop expects an mbuf to free. */
 971                 DPFPRINTF(("refragment error %d\n", error));
 972                 action = PF_DROP;
 973         }
 974         for (t = m; m; m = t) {
 975                 t = m->m_nextpkt;
 976                 m->m_nextpkt = NULL;
 977                 m->m_flags |= M_SKIP_FIREWALL;
 978                 memset(&pd, 0, sizeof(pd));
 979                 pd.pf_mtag = pf_find_mtag(m);
 980                 if (error == 0)
 981                         ip6_forward(m, 0);
 982                 else
 983                         m_freem(m);
 984         }
 985
 986         return (action);
 987 }
 988 #endif /* INET6 */
 989
 990 #ifdef INET
 991 int
 992 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason,
 993     struct pf_pdesc *pd)
 994 {
 995         struct mbuf             *m = *m0;
 996         struct pf_rule          *r;
 997         struct ip               *h = mtod(m, struct ip *);
 998         int                      mff = (ntohs(h->ip_off) & IP_MF);
 999         int                      hlen = h->ip_hl << 2;
1000         u_int16_t                fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
1001         u_int16_t                max;
1002         int                      ip_len;
1003         int                      ip_off;
1004         int                      tag = -1;
1005         int                      verdict;
1006
1007         PF_RULES_RASSERT();
1008
1009         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1010         while (r != NULL) {
1011                 r->evaluations++;
1012                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1013                         r = r->skip[PF_SKIP_IFP].ptr;
1014                 else if (r->direction && r->direction != dir)
1015                         r = r->skip[PF_SKIP_DIR].ptr;
1016                 else if (r->af && r->af != AF_INET)
1017                         r = r->skip[PF_SKIP_AF].ptr;
1018                 else if (r->proto && r->proto != h->ip_p)
1019                         r = r->skip[PF_SKIP_PROTO].ptr;
1020                 else if (PF_MISMATCHAW(&r->src.addr,
1021                     (struct pf_addr *)&h->ip_src.s_addr, AF_INET,
1022                     r->src.neg, kif, M_GETFIB(m)))
1023                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1024                 else if (PF_MISMATCHAW(&r->dst.addr,
1025                     (struct pf_addr *)&h->ip_dst.s_addr, AF_INET,
1026                     r->dst.neg, NULL, M_GETFIB(m)))
1027                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1028                 else if (r->match_tag && !pf_match_tag(m, r, &tag,
1029                     pd->pf_mtag ? pd->pf_mtag->tag : 0))
1030                         r = TAILQ_NEXT(r, entries);
1031                 else
1032                         break;
1033         }
1034
1035         if (r == NULL || r->action == PF_NOSCRUB)
1036                 return (PF_PASS);
1037         else {
1038                 r->packets[dir == PF_OUT]++;
1039                 r->bytes[dir == PF_OUT] += pd->tot_len;
1040         }
1041
1042         /* Check for illegal packets */
1043         if (hlen < (int)sizeof(struct ip)) {
1044                 REASON_SET(reason, PFRES_NORM);
1045                 goto drop;
1046         }
1047
1048         if (hlen > ntohs(h->ip_len)) {
1049                 REASON_SET(reason, PFRES_NORM);
1050                 goto drop;
1051         }
1052
1053         /* Clear IP_DF if the rule uses the no-df option */
1054         if (r->rule_flag & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
1055                 u_int16_t ip_off = h->ip_off;
1056
1057                 h->ip_off &= htons(~IP_DF);
1058                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1059         }
1060
1061         /* We will need other tests here */
1062         if (!fragoff && !mff)
1063                 goto no_fragment;
1064
1065         /* We're dealing with a fragment now. Don't allow fragments
1066          * with IP_DF to enter the cache. If the flag was cleared by
1067          * no-df above, fine. Otherwise drop it.
1068          */
1069         if (h->ip_off & htons(IP_DF)) {
1070                 DPFPRINTF(("IP_DF\n"));
1071                 goto bad;
1072         }
1073
1074         ip_len = ntohs(h->ip_len) - hlen;
1075         ip_off = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
1076
1077         /* All fragments are 8 byte aligned */
1078         if (mff && (ip_len & 0x7)) {
1079                 DPFPRINTF(("mff and %d\n", ip_len));
1080                 goto bad;
1081         }
1082
1083         /* Respect maximum length */
1084         if (fragoff + ip_len > IP_MAXPACKET) {
1085                 DPFPRINTF(("max packet %d\n", fragoff + ip_len));
1086                 goto bad;
1087         }
1088         max = fragoff + ip_len;
1089
1090         /* Fully buffer all of the fragments
1091          * Might return a completely reassembled mbuf, or NULL */
1092         PF_FRAG_LOCK();
1093         DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
1094         verdict = pf_reassemble(m0, h, dir, reason);
1095         PF_FRAG_UNLOCK();
1096
1097         if (verdict != PF_PASS)
1098                 return (PF_DROP);
1099
1100         m = *m0;
1101         if (m == NULL)
1102                 return (PF_DROP);
1103
1104         h = mtod(m, struct ip *);
1105
1106  no_fragment:
1107         /* At this point, only IP_DF is allowed in ip_off */
1108         if (h->ip_off & ~htons(IP_DF)) {
1109                 u_int16_t ip_off = h->ip_off;
1110
1111                 h->ip_off &= htons(IP_DF);
1112                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1113         }
1114
1115         pf_scrub_ip(&m, r->rule_flag, r->min_ttl, r->set_tos);
1116
1117         return (PF_PASS);
1118
1119  bad:
1120         DPFPRINTF(("dropping bad fragment\n"));
1121         REASON_SET(reason, PFRES_FRAG);
1122  drop:
1123         if (r != NULL && r->log)
1124                 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
1125                     1);
1126
1127         return (PF_DROP);
1128 }
1129 #endif
1130
1131 #ifdef INET6
1132 int
1133 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif,
1134     u_short *reason, struct pf_pdesc *pd)
1135 {
1136         struct mbuf             *m = *m0;
1137         struct pf_rule          *r;
1138         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
1139         int                      extoff;
1140         int                      off;
1141         struct ip6_ext           ext;
1142         struct ip6_opt           opt;
1143         struct ip6_frag          frag;
1144         u_int32_t                plen;
1145         int                      optend;
1146         int                      ooff;
1147         u_int8_t                 proto;
1148         int                      terminal;
1149
1150         PF_RULES_RASSERT();
1151
1152         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1153         while (r != NULL) {
1154                 r->evaluations++;
1155                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1156                         r = r->skip[PF_SKIP_IFP].ptr;
1157                 else if (r->direction && r->direction != dir)
1158                         r = r->skip[PF_SKIP_DIR].ptr;
1159                 else if (r->af && r->af != AF_INET6)
1160                         r = r->skip[PF_SKIP_AF].ptr;
1161 #if 0 /* header chain! */
1162                 else if (r->proto && r->proto != h->ip6_nxt)
1163                         r = r->skip[PF_SKIP_PROTO].ptr;
1164 #endif
1165                 else if (PF_MISMATCHAW(&r->src.addr,
1166                     (struct pf_addr *)&h->ip6_src, AF_INET6,
1167                     r->src.neg, kif, M_GETFIB(m)))
1168                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1169                 else if (PF_MISMATCHAW(&r->dst.addr,
1170                     (struct pf_addr *)&h->ip6_dst, AF_INET6,
1171                     r->dst.neg, NULL, M_GETFIB(m)))
1172                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1173                 else
1174                         break;
1175         }
1176
1177         if (r == NULL || r->action == PF_NOSCRUB)
1178                 return (PF_PASS);
1179         else {
1180                 r->packets[dir == PF_OUT]++;
1181                 r->bytes[dir == PF_OUT] += pd->tot_len;
1182         }
1183
1184         /* Check for illegal packets */
1185         if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len)
1186                 goto drop;
1187
1188         plen = ntohs(h->ip6_plen);
1189         /* jumbo payload option not supported */
1190         if (plen == 0)
1191                 goto drop;
1192
1193         extoff = 0;
1194         off = sizeof(struct ip6_hdr);
1195         proto = h->ip6_nxt;
1196         terminal = 0;
1197         do {
1198                 switch (proto) {
1199                 case IPPROTO_FRAGMENT:
1200                         goto fragment;
1201                         break;
1202                 case IPPROTO_AH:
1203                 case IPPROTO_ROUTING:
1204                 case IPPROTO_DSTOPTS:
1205                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1206                             NULL, AF_INET6))
1207                                 goto shortpkt;
1208                         extoff = off;
1209                         if (proto == IPPROTO_AH)
1210                                 off += (ext.ip6e_len + 2) * 4;
1211                         else
1212                                 off += (ext.ip6e_len + 1) * 8;
1213                         proto = ext.ip6e_nxt;
1214                         break;
1215                 case IPPROTO_HOPOPTS:
1216                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1217                             NULL, AF_INET6))
1218                                 goto shortpkt;
1219                         extoff = off;
1220                         optend = off + (ext.ip6e_len + 1) * 8;
1221                         ooff = off + sizeof(ext);
1222                         do {
1223                                 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type,
1224                                     sizeof(opt.ip6o_type), NULL, NULL,
1225                                     AF_INET6))
1226                                         goto shortpkt;
1227                                 if (opt.ip6o_type == IP6OPT_PAD1) {
1228                                         ooff++;
1229                                         continue;
1230                                 }
1231                                 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt),
1232                                     NULL, NULL, AF_INET6))
1233                                         goto shortpkt;
1234                                 if (ooff + sizeof(opt) + opt.ip6o_len > optend)
1235                                         goto drop;
1236                                 if (opt.ip6o_type == IP6OPT_JUMBO)
1237                                         goto drop;
1238                                 ooff += sizeof(opt) + opt.ip6o_len;
1239                         } while (ooff < optend);
1240
1241                         off = optend;
1242                         proto = ext.ip6e_nxt;
1243                         break;
1244                 default:
1245                         terminal = 1;
1246                         break;
1247                 }
1248         } while (!terminal);
1249
1250         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1251                 goto shortpkt;
1252
1253         pf_scrub_ip6(&m, r->min_ttl);
1254
1255         return (PF_PASS);
1256
1257  fragment:
1258         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1259                 goto shortpkt;
1260
1261         if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6))
1262                 goto shortpkt;
1263
1264         /* Offset now points to data portion. */
1265         off += sizeof(frag);
1266
1267         /* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */
1268         if (pf_reassemble6(m0, h, &frag, off, extoff, reason) != PF_PASS)
1269                 return (PF_DROP);
1270         m = *m0;
1271         if (m == NULL)
1272                 return (PF_DROP);
1273
1274         pd->flags |= PFDESC_IP_REAS;
1275         return (PF_PASS);
1276
1277  shortpkt:
1278         REASON_SET(reason, PFRES_SHORT);
1279         if (r != NULL && r->log)
1280                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1281                     1);
1282         return (PF_DROP);
1283
1284  drop:
1285         REASON_SET(reason, PFRES_NORM);
1286         if (r != NULL && r->log)
1287                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1288                     1);
1289         return (PF_DROP);
1290 }
1291 #endif /* INET6 */
1292
1293 int
1294 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff,
1295     int off, void *h, struct pf_pdesc *pd)
1296 {
1297         struct pf_rule  *r, *rm = NULL;
1298         struct tcphdr   *th = pd->hdr.tcp;
1299         int              rewrite = 0;
1300         u_short          reason;
1301         u_int8_t         flags;
1302         sa_family_t      af = pd->af;
1303
1304         PF_RULES_RASSERT();
1305
1306         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1307         while (r != NULL) {
1308                 r->evaluations++;
1309                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1310                         r = r->skip[PF_SKIP_IFP].ptr;
1311                 else if (r->direction && r->direction != dir)
1312                         r = r->skip[PF_SKIP_DIR].ptr;
1313                 else if (r->af && r->af != af)
1314                         r = r->skip[PF_SKIP_AF].ptr;
1315                 else if (r->proto && r->proto != pd->proto)
1316                         r = r->skip[PF_SKIP_PROTO].ptr;
1317                 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af,
1318                     r->src.neg, kif, M_GETFIB(m)))
1319                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1320                 else if (r->src.port_op && !pf_match_port(r->src.port_op,
1321                             r->src.port[0], r->src.port[1], th->th_sport))
1322                         r = r->skip[PF_SKIP_SRC_PORT].ptr;
1323                 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af,
1324                     r->dst.neg, NULL, M_GETFIB(m)))
1325                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1326                 else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
1327                             r->dst.port[0], r->dst.port[1], th->th_dport))
1328                         r = r->skip[PF_SKIP_DST_PORT].ptr;
1329                 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match(
1330                             pf_osfp_fingerprint(pd, m, off, th),
1331                             r->os_fingerprint))
1332                         r = TAILQ_NEXT(r, entries);
1333                 else {
1334                         rm = r;
1335                         break;
1336                 }
1337         }
1338
1339         if (rm == NULL || rm->action == PF_NOSCRUB)
1340                 return (PF_PASS);
1341         else {
1342                 r->packets[dir == PF_OUT]++;
1343                 r->bytes[dir == PF_OUT] += pd->tot_len;
1344         }
1345
1346         if (rm->rule_flag & PFRULE_REASSEMBLE_TCP)
1347                 pd->flags |= PFDESC_TCP_NORM;
1348
1349         flags = th->th_flags;
1350         if (flags & TH_SYN) {
1351                 /* Illegal packet */
1352                 if (flags & TH_RST)
1353                         goto tcp_drop;
1354
1355                 if (flags & TH_FIN)
1356                         goto tcp_drop;
1357         } else {
1358                 /* Illegal packet */
1359                 if (!(flags & (TH_ACK|TH_RST)))
1360                         goto tcp_drop;
1361         }
1362
1363         if (!(flags & TH_ACK)) {
1364                 /* These flags are only valid if ACK is set */
1365                 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG))
1366                         goto tcp_drop;
1367         }
1368
1369         /* Check for illegal header length */
1370         if (th->th_off < (sizeof(struct tcphdr) >> 2))
1371                 goto tcp_drop;
1372
1373         /* If flags changed, or reserved data set, then adjust */
1374         if (flags != th->th_flags || th->th_x2 != 0) {
1375                 u_int16_t       ov, nv;
1376
1377                 ov = *(u_int16_t *)(&th->th_ack + 1);
1378                 th->th_flags = flags;
1379                 th->th_x2 = 0;
1380                 nv = *(u_int16_t *)(&th->th_ack + 1);
1381
1382                 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, ov, nv, 0);
1383                 rewrite = 1;
1384         }
1385
1386         /* Remove urgent pointer, if TH_URG is not set */
1387         if (!(flags & TH_URG) && th->th_urp) {
1388                 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, th->th_urp,
1389                     0, 0);
1390                 th->th_urp = 0;
1391                 rewrite = 1;
1392         }
1393
1394         /* Process options */
1395         if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af))
1396                 rewrite = 1;
1397
1398         /* copy back packet headers if we sanitized */
1399         if (rewrite)
1400                 m_copyback(m, off, sizeof(*th), (caddr_t)th);
1401
1402         return (PF_PASS);
1403
1404  tcp_drop:
1405         REASON_SET(&reason, PFRES_NORM);
1406         if (rm != NULL && r->log)
1407                 PFLOG_PACKET(kif, m, AF_INET, dir, reason, r, NULL, NULL, pd,
1408                     1);
1409         return (PF_DROP);
1410 }
1411
1412 int
1413 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd,
1414     struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst)
1415 {
1416         u_int32_t tsval, tsecr;
1417         u_int8_t hdr[60];
1418         u_int8_t *opt;
1419
1420         KASSERT((src->scrub == NULL),
1421             ("pf_normalize_tcp_init: src->scrub != NULL"));
1422
1423         src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT);
1424         if (src->scrub == NULL)
1425                 return (1);
1426
1427         switch (pd->af) {
1428 #ifdef INET
1429         case AF_INET: {
1430                 struct ip *h = mtod(m, struct ip *);
1431                 src->scrub->pfss_ttl = h->ip_ttl;
1432                 break;
1433         }
1434 #endif /* INET */
1435 #ifdef INET6
1436         case AF_INET6: {
1437                 struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1438                 src->scrub->pfss_ttl = h->ip6_hlim;
1439                 break;
1440         }
1441 #endif /* INET6 */
1442         }
1443
1444
1445         /*
1446          * All normalizations below are only begun if we see the start of
1447          * the connections.  They must all set an enabled bit in pfss_flags
1448          */
1449         if ((th->th_flags & TH_SYN) == 0)
1450                 return (0);
1451
1452
1453         if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub &&
1454             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1455                 /* Diddle with TCP options */
1456                 int hlen;
1457                 opt = hdr + sizeof(struct tcphdr);
1458                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1459                 while (hlen >= TCPOLEN_TIMESTAMP) {
1460                         switch (*opt) {
1461                         case TCPOPT_EOL:        /* FALLTHROUGH */
1462                         case TCPOPT_NOP:
1463                                 opt++;
1464                                 hlen--;
1465                                 break;
1466                         case TCPOPT_TIMESTAMP:
1467                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1468                                         src->scrub->pfss_flags |=
1469                                             PFSS_TIMESTAMP;
1470                                         src->scrub->pfss_ts_mod =
1471                                             htonl(arc4random());
1472
1473                                         /* note PFSS_PAWS not set yet */
1474                                         memcpy(&tsval, &opt[2],
1475                                             sizeof(u_int32_t));
1476                                         memcpy(&tsecr, &opt[6],
1477                                             sizeof(u_int32_t));
1478                                         src->scrub->pfss_tsval0 = ntohl(tsval);
1479                                         src->scrub->pfss_tsval = ntohl(tsval);
1480                                         src->scrub->pfss_tsecr = ntohl(tsecr);
1481                                         getmicrouptime(&src->scrub->pfss_last);
1482                                 }
1483                                 /* FALLTHROUGH */
1484                         default:
1485                                 hlen -= MAX(opt[1], 2);
1486                                 opt += MAX(opt[1], 2);
1487                                 break;
1488                         }
1489                 }
1490         }
1491
1492         return (0);
1493 }
1494
1495 void
1496 pf_normalize_tcp_cleanup(struct pf_state *state)
1497 {
1498         if (state->src.scrub)
1499                 uma_zfree(V_pf_state_scrub_z, state->src.scrub);
1500         if (state->dst.scrub)
1501                 uma_zfree(V_pf_state_scrub_z, state->dst.scrub);
1502
1503         /* Someday... flush the TCP segment reassembly descriptors. */
1504 }
1505
1506 int
1507 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd,
1508     u_short *reason, struct tcphdr *th, struct pf_state *state,
1509     struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback)
1510 {
1511         struct timeval uptime;
1512         u_int32_t tsval, tsecr;
1513         u_int tsval_from_last;
1514         u_int8_t hdr[60];
1515         u_int8_t *opt;
1516         int copyback = 0;
1517         int got_ts = 0;
1518
1519         KASSERT((src->scrub || dst->scrub),
1520             ("%s: src->scrub && dst->scrub!", __func__));
1521
1522         /*
1523          * Enforce the minimum TTL seen for this connection.  Negate a common
1524          * technique to evade an intrusion detection system and confuse
1525          * firewall state code.
1526          */
1527         switch (pd->af) {
1528 #ifdef INET
1529         case AF_INET: {
1530                 if (src->scrub) {
1531                         struct ip *h = mtod(m, struct ip *);
1532                         if (h->ip_ttl > src->scrub->pfss_ttl)
1533                                 src->scrub->pfss_ttl = h->ip_ttl;
1534                         h->ip_ttl = src->scrub->pfss_ttl;
1535                 }
1536                 break;
1537         }
1538 #endif /* INET */
1539 #ifdef INET6
1540         case AF_INET6: {
1541                 if (src->scrub) {
1542                         struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1543                         if (h->ip6_hlim > src->scrub->pfss_ttl)
1544                                 src->scrub->pfss_ttl = h->ip6_hlim;
1545                         h->ip6_hlim = src->scrub->pfss_ttl;
1546                 }
1547                 break;
1548         }
1549 #endif /* INET6 */
1550         }
1551
1552         if (th->th_off > (sizeof(struct tcphdr) >> 2) &&
1553             ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) ||
1554             (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) &&
1555             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1556                 /* Diddle with TCP options */
1557                 int hlen;
1558                 opt = hdr + sizeof(struct tcphdr);
1559                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1560                 while (hlen >= TCPOLEN_TIMESTAMP) {
1561                         switch (*opt) {
1562                         case TCPOPT_EOL:        /* FALLTHROUGH */
1563                         case TCPOPT_NOP:
1564                                 opt++;
1565                                 hlen--;
1566                                 break;
1567                         case TCPOPT_TIMESTAMP:
1568                                 /* Modulate the timestamps.  Can be used for
1569                                  * NAT detection, OS uptime determination or
1570                                  * reboot detection.
1571                                  */
1572
1573                                 if (got_ts) {
1574                                         /* Huh?  Multiple timestamps!? */
1575                                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1576                                                 DPFPRINTF(("multiple TS??\n"));
1577                                                 pf_print_state(state);
1578                                                 printf("\n");
1579                                         }
1580                                         REASON_SET(reason, PFRES_TS);
1581                                         return (PF_DROP);
1582                                 }
1583                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1584                                         memcpy(&tsval, &opt[2],
1585                                             sizeof(u_int32_t));
1586                                         if (tsval && src->scrub &&
1587                                             (src->scrub->pfss_flags &
1588                                             PFSS_TIMESTAMP)) {
1589                                                 tsval = ntohl(tsval);
1590                                                 pf_change_proto_a(m, &opt[2],
1591                                                     &th->th_sum,
1592                                                     htonl(tsval +
1593                                                     src->scrub->pfss_ts_mod),
1594                                                     0);
1595                                                 copyback = 1;
1596                                         }
1597
1598                                         /* Modulate TS reply iff valid (!0) */
1599                                         memcpy(&tsecr, &opt[6],
1600                                             sizeof(u_int32_t));
1601                                         if (tsecr && dst->scrub &&
1602                                             (dst->scrub->pfss_flags &
1603                                             PFSS_TIMESTAMP)) {
1604                                                 tsecr = ntohl(tsecr)
1605                                                     - dst->scrub->pfss_ts_mod;
1606                                                 pf_change_proto_a(m, &opt[6],
1607                                                     &th->th_sum, htonl(tsecr),
1608                                                     0);
1609                                                 copyback = 1;
1610                                         }
1611                                         got_ts = 1;
1612                                 }
1613                                 /* FALLTHROUGH */
1614                         default:
1615                                 hlen -= MAX(opt[1], 2);
1616                                 opt += MAX(opt[1], 2);
1617                                 break;
1618                         }
1619                 }
1620                 if (copyback) {
1621                         /* Copyback the options, caller copys back header */
1622                         *writeback = 1;
1623                         m_copyback(m, off + sizeof(struct tcphdr),
1624                             (th->th_off << 2) - sizeof(struct tcphdr), hdr +
1625                             sizeof(struct tcphdr));
1626                 }
1627         }
1628
1629
1630         /*
1631          * Must invalidate PAWS checks on connections idle for too long.
1632          * The fastest allowed timestamp clock is 1ms.  That turns out to
1633          * be about 24 days before it wraps.  XXX Right now our lowerbound
1634          * TS echo check only works for the first 12 days of a connection
1635          * when the TS has exhausted half its 32bit space
1636          */
1637 #define TS_MAX_IDLE     (24*24*60*60)
1638 #define TS_MAX_CONN     (12*24*60*60)   /* XXX remove when better tsecr check */
1639
1640         getmicrouptime(&uptime);
1641         if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) &&
1642             (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE ||
1643             time_uptime - state->creation > TS_MAX_CONN))  {
1644                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1645                         DPFPRINTF(("src idled out of PAWS\n"));
1646                         pf_print_state(state);
1647                         printf("\n");
1648                 }
1649                 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS)
1650                     | PFSS_PAWS_IDLED;
1651         }
1652         if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) &&
1653             uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) {
1654                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1655                         DPFPRINTF(("dst idled out of PAWS\n"));
1656                         pf_print_state(state);
1657                         printf("\n");
1658                 }
1659                 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS)
1660                     | PFSS_PAWS_IDLED;
1661         }
1662
1663         if (got_ts && src->scrub && dst->scrub &&
1664             (src->scrub->pfss_flags & PFSS_PAWS) &&
1665             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1666                 /* Validate that the timestamps are "in-window".
1667                  * RFC1323 describes TCP Timestamp options that allow
1668                  * measurement of RTT (round trip time) and PAWS
1669                  * (protection against wrapped sequence numbers).  PAWS
1670                  * gives us a set of rules for rejecting packets on
1671                  * long fat pipes (packets that were somehow delayed
1672                  * in transit longer than the time it took to send the
1673                  * full TCP sequence space of 4Gb).  We can use these
1674                  * rules and infer a few others that will let us treat
1675                  * the 32bit timestamp and the 32bit echoed timestamp
1676                  * as sequence numbers to prevent a blind attacker from
1677                  * inserting packets into a connection.
1678                  *
1679                  * RFC1323 tells us:
1680                  *  - The timestamp on this packet must be greater than
1681                  *    or equal to the last value echoed by the other
1682                  *    endpoint.  The RFC says those will be discarded
1683                  *    since it is a dup that has already been acked.
1684                  *    This gives us a lowerbound on the timestamp.
1685                  *        timestamp >= other last echoed timestamp
1686                  *  - The timestamp will be less than or equal to
1687                  *    the last timestamp plus the time between the
1688                  *    last packet and now.  The RFC defines the max
1689                  *    clock rate as 1ms.  We will allow clocks to be
1690                  *    up to 10% fast and will allow a total difference
1691                  *    or 30 seconds due to a route change.  And this
1692                  *    gives us an upperbound on the timestamp.
1693                  *        timestamp <= last timestamp + max ticks
1694                  *    We have to be careful here.  Windows will send an
1695                  *    initial timestamp of zero and then initialize it
1696                  *    to a random value after the 3whs; presumably to
1697                  *    avoid a DoS by having to call an expensive RNG
1698                  *    during a SYN flood.  Proof MS has at least one
1699                  *    good security geek.
1700                  *
1701                  *  - The TCP timestamp option must also echo the other
1702                  *    endpoints timestamp.  The timestamp echoed is the
1703                  *    one carried on the earliest unacknowledged segment
1704                  *    on the left edge of the sequence window.  The RFC
1705                  *    states that the host will reject any echoed
1706                  *    timestamps that were larger than any ever sent.
1707                  *    This gives us an upperbound on the TS echo.
1708                  *        tescr <= largest_tsval
1709                  *  - The lowerbound on the TS echo is a little more
1710                  *    tricky to determine.  The other endpoint's echoed
1711                  *    values will not decrease.  But there may be
1712                  *    network conditions that re-order packets and
1713                  *    cause our view of them to decrease.  For now the
1714                  *    only lowerbound we can safely determine is that
1715                  *    the TS echo will never be less than the original
1716                  *    TS.  XXX There is probably a better lowerbound.
1717                  *    Remove TS_MAX_CONN with better lowerbound check.
1718                  *        tescr >= other original TS
1719                  *
1720                  * It is also important to note that the fastest
1721                  * timestamp clock of 1ms will wrap its 32bit space in
1722                  * 24 days.  So we just disable TS checking after 24
1723                  * days of idle time.  We actually must use a 12d
1724                  * connection limit until we can come up with a better
1725                  * lowerbound to the TS echo check.
1726                  */
1727                 struct timeval delta_ts;
1728                 int ts_fudge;
1729
1730
1731                 /*
1732                  * PFTM_TS_DIFF is how many seconds of leeway to allow
1733                  * a host's timestamp.  This can happen if the previous
1734                  * packet got delayed in transit for much longer than
1735                  * this packet.
1736                  */
1737                 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0)
1738                         ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF];
1739
1740                 /* Calculate max ticks since the last timestamp */
1741 #define TS_MAXFREQ      1100            /* RFC max TS freq of 1Khz + 10% skew */
1742 #define TS_MICROSECS    1000000         /* microseconds per second */
1743                 delta_ts = uptime;
1744                 timevalsub(&delta_ts, &src->scrub->pfss_last);
1745                 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ;
1746                 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ);
1747
1748                 if ((src->state >= TCPS_ESTABLISHED &&
1749                     dst->state >= TCPS_ESTABLISHED) &&
1750                     (SEQ_LT(tsval, dst->scrub->pfss_tsecr) ||
1751                     SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) ||
1752                     (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) ||
1753                     SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) {
1754                         /* Bad RFC1323 implementation or an insertion attack.
1755                          *
1756                          * - Solaris 2.6 and 2.7 are known to send another ACK
1757                          *   after the FIN,FIN|ACK,ACK closing that carries
1758                          *   an old timestamp.
1759                          */
1760
1761                         DPFPRINTF(("Timestamp failed %c%c%c%c\n",
1762                             SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ',
1763                             SEQ_GT(tsval, src->scrub->pfss_tsval +
1764                             tsval_from_last) ? '1' : ' ',
1765                             SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ',
1766                             SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' '));
1767                         DPFPRINTF((" tsval: %u  tsecr: %u  +ticks: %u  "
1768                             "idle: %jus %lums\n",
1769                             tsval, tsecr, tsval_from_last,
1770                             (uintmax_t)delta_ts.tv_sec,
1771                             delta_ts.tv_usec / 1000));
1772                         DPFPRINTF((" src->tsval: %u  tsecr: %u\n",
1773                             src->scrub->pfss_tsval, src->scrub->pfss_tsecr));
1774                         DPFPRINTF((" dst->tsval: %u  tsecr: %u  tsval0: %u"
1775                             "\n", dst->scrub->pfss_tsval,
1776                             dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0));
1777                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1778                                 pf_print_state(state);
1779                                 pf_print_flags(th->th_flags);
1780                                 printf("\n");
1781                         }
1782                         REASON_SET(reason, PFRES_TS);
1783                         return (PF_DROP);
1784                 }
1785
1786                 /* XXX I'd really like to require tsecr but it's optional */
1787
1788         } else if (!got_ts && (th->th_flags & TH_RST) == 0 &&
1789             ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED)
1790             || pd->p_len > 0 || (th->th_flags & TH_SYN)) &&
1791             src->scrub && dst->scrub &&
1792             (src->scrub->pfss_flags & PFSS_PAWS) &&
1793             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1794                 /* Didn't send a timestamp.  Timestamps aren't really useful
1795                  * when:
1796                  *  - connection opening or closing (often not even sent).
1797                  *    but we must not let an attacker to put a FIN on a
1798                  *    data packet to sneak it through our ESTABLISHED check.
1799                  *  - on a TCP reset.  RFC suggests not even looking at TS.
1800                  *  - on an empty ACK.  The TS will not be echoed so it will
1801                  *    probably not help keep the RTT calculation in sync and
1802                  *    there isn't as much danger when the sequence numbers
1803                  *    got wrapped.  So some stacks don't include TS on empty
1804                  *    ACKs :-(
1805                  *
1806                  * To minimize the disruption to mostly RFC1323 conformant
1807                  * stacks, we will only require timestamps on data packets.
1808                  *
1809                  * And what do ya know, we cannot require timestamps on data
1810                  * packets.  There appear to be devices that do legitimate
1811                  * TCP connection hijacking.  There are HTTP devices that allow
1812                  * a 3whs (with timestamps) and then buffer the HTTP request.
1813                  * If the intermediate device has the HTTP response cache, it
1814                  * will spoof the response but not bother timestamping its
1815                  * packets.  So we can look for the presence of a timestamp in
1816                  * the first data packet and if there, require it in all future
1817                  * packets.
1818                  */
1819
1820                 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) {
1821                         /*
1822                          * Hey!  Someone tried to sneak a packet in.  Or the
1823                          * stack changed its RFC1323 behavior?!?!
1824                          */
1825                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1826                                 DPFPRINTF(("Did not receive expected RFC1323 "
1827                                     "timestamp\n"));
1828                                 pf_print_state(state);
1829                                 pf_print_flags(th->th_flags);
1830                                 printf("\n");
1831                         }
1832                         REASON_SET(reason, PFRES_TS);
1833                         return (PF_DROP);
1834                 }
1835         }
1836
1837
1838         /*
1839          * We will note if a host sends his data packets with or without
1840          * timestamps.  And require all data packets to contain a timestamp
1841          * if the first does.  PAWS implicitly requires that all data packets be
1842          * timestamped.  But I think there are middle-man devices that hijack
1843          * TCP streams immediately after the 3whs and don't timestamp their
1844          * packets (seen in a WWW accelerator or cache).
1845          */
1846         if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags &
1847             (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) {
1848                 if (got_ts)
1849                         src->scrub->pfss_flags |= PFSS_DATA_TS;
1850                 else {
1851                         src->scrub->pfss_flags |= PFSS_DATA_NOTS;
1852                         if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub &&
1853                             (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) {
1854                                 /* Don't warn if other host rejected RFC1323 */
1855                                 DPFPRINTF(("Broken RFC1323 stack did not "
1856                                     "timestamp data packet. Disabled PAWS "
1857                                     "security.\n"));
1858                                 pf_print_state(state);
1859                                 pf_print_flags(th->th_flags);
1860                                 printf("\n");
1861                         }
1862                 }
1863         }
1864
1865
1866         /*
1867          * Update PAWS values
1868          */
1869         if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags &
1870             (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) {
1871                 getmicrouptime(&src->scrub->pfss_last);
1872                 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) ||
1873                     (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1874                         src->scrub->pfss_tsval = tsval;
1875
1876                 if (tsecr) {
1877                         if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) ||
1878                             (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1879                                 src->scrub->pfss_tsecr = tsecr;
1880
1881                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 &&
1882                             (SEQ_LT(tsval, src->scrub->pfss_tsval0) ||
1883                             src->scrub->pfss_tsval0 == 0)) {
1884                                 /* tsval0 MUST be the lowest timestamp */
1885                                 src->scrub->pfss_tsval0 = tsval;
1886                         }
1887
1888                         /* Only fully initialized after a TS gets echoed */
1889                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0)
1890                                 src->scrub->pfss_flags |= PFSS_PAWS;
1891                 }
1892         }
1893
1894         /* I have a dream....  TCP segment reassembly.... */
1895         return (0);
1896 }
1897
1898 static int
1899 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th,
1900     int off, sa_family_t af)
1901 {
1902         u_int16_t       *mss;
1903         int              thoff;
1904         int              opt, cnt, optlen = 0;
1905         int              rewrite = 0;
1906         u_char           opts[TCP_MAXOLEN];
1907         u_char          *optp = opts;
1908
1909         thoff = th->th_off << 2;
1910         cnt = thoff - sizeof(struct tcphdr);
1911
1912         if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt,
1913             NULL, NULL, af))
1914                 return (rewrite);
1915
1916         for (; cnt > 0; cnt -= optlen, optp += optlen) {
1917                 opt = optp[0];
1918                 if (opt == TCPOPT_EOL)
1919                         break;
1920                 if (opt == TCPOPT_NOP)
1921                         optlen = 1;
1922                 else {
1923                         if (cnt < 2)
1924                                 break;
1925                         optlen = optp[1];
1926                         if (optlen < 2 || optlen > cnt)
1927                                 break;
1928                 }
1929                 switch (opt) {
1930                 case TCPOPT_MAXSEG:
1931                         mss = (u_int16_t *)(optp + 2);
1932                         if ((ntohs(*mss)) > r->max_mss) {
1933                                 th->th_sum = pf_proto_cksum_fixup(m,
1934                                     th->th_sum, *mss, htons(r->max_mss), 0);
1935                                 *mss = htons(r->max_mss);
1936                                 rewrite = 1;
1937                         }
1938                         break;
1939                 default:
1940                         break;
1941                 }
1942         }
1943
1944         if (rewrite)
1945                 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts);
1946
1947         return (rewrite);
1948 }
1949
1950 #ifdef INET
1951 static void
1952 pf_scrub_ip(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos)
1953 {
1954         struct mbuf             *m = *m0;
1955         struct ip               *h = mtod(m, struct ip *);
1956
1957         /* Clear IP_DF if no-df was requested */
1958         if (flags & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
1959                 u_int16_t ip_off = h->ip_off;
1960
1961                 h->ip_off &= htons(~IP_DF);
1962                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1963         }
1964
1965         /* Enforce a minimum ttl, may cause endless packet loops */
1966         if (min_ttl && h->ip_ttl < min_ttl) {
1967                 u_int16_t ip_ttl = h->ip_ttl;
1968
1969                 h->ip_ttl = min_ttl;
1970                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
1971         }
1972
1973         /* Enforce tos */
1974         if (flags & PFRULE_SET_TOS) {
1975                 u_int16_t       ov, nv;
1976
1977                 ov = *(u_int16_t *)h;
1978                 h->ip_tos = tos | (h->ip_tos & IPTOS_ECN_MASK);
1979                 nv = *(u_int16_t *)h;
1980
1981                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0);
1982         }
1983
1984         /* random-id, but not for fragments */
1985         if (flags & PFRULE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) {
1986                 uint16_t ip_id = h->ip_id;
1987
1988                 ip_fillid(h);
1989                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0);
1990         }
1991 }
1992 #endif /* INET */
1993
1994 #ifdef INET6
1995 static void
1996 pf_scrub_ip6(struct mbuf **m0, u_int8_t min_ttl)
1997 {
1998         struct mbuf             *m = *m0;
1999         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
2000
2001         /* Enforce a minimum ttl, may cause endless packet loops */
2002         if (min_ttl && h->ip6_hlim < min_ttl)
2003                 h->ip6_hlim = min_ttl;
2004 }
2005 #endif