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"));
 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", 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",
 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" : "reass frag %#08x @ %d-%d",
 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", 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", 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"));
 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", 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", 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", frag->fr_id, frag->fr_holes));
 834                 PF_FRAG_UNLOCK();
 835                 return (PF_PASS);  /* Drop because *m0 is NULL, no error. */
 836         }
 837
 838         /* We have all the data. */
 839         frent = TAILQ_FIRST(&frag->fr_queue);
 840         KASSERT(frent != NULL, ("frent != NULL"));
 841         extoff = frent->fe_extoff;
 842         maxlen = frag->fr_maxlen;
 843         frag_id = frag->fr_id;
 844         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 845                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 846         hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag);
 847
 848         m = *m0 = pf_join_fragment(frag);
 849         frag = NULL;
 850
 851         PF_FRAG_UNLOCK();
 852
 853         /* Take protocol from first fragment header. */
 854         m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off);
 855         KASSERT(m, ("%s: short mbuf chain", __func__));
 856         proto = *(mtod(m, caddr_t) + off);
 857         m = *m0;
 858
 859         /* Delete frag6 header */
 860         if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0)
 861                 goto fail;
 862
 863         if (m->m_flags & M_PKTHDR) {
 864                 int plen = 0;
 865                 for (m = *m0; m; m = m->m_next)
 866                         plen += m->m_len;
 867                 m = *m0;
 868                 m->m_pkthdr.len = plen;
 869         }
 870
 871         if ((mtag = m_tag_get(PF_REASSEMBLED, sizeof(struct pf_fragment_tag),
 872             M_NOWAIT)) == NULL)
 873                 goto fail;
 874         ftag = (struct pf_fragment_tag *)(mtag + 1);
 875         ftag->ft_hdrlen = hdrlen;
 876         ftag->ft_extoff = extoff;
 877         ftag->ft_maxlen = maxlen;
 878         ftag->ft_id = frag_id;
 879         m_tag_prepend(m, mtag);
 880
 881         ip6 = mtod(m, struct ip6_hdr *);
 882         ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total);
 883         if (extoff) {
 884                 /* Write protocol into next field of last extension header. */
 885                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
 886                     &off);
 887                 KASSERT(m, ("%s: short mbuf chain", __func__));
 888                 *(mtod(m, char *) + off) = proto;
 889                 m = *m0;
 890         } else
 891                 ip6->ip6_nxt = proto;
 892
 893         if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) {
 894                 DPFPRINTF(("drop: too big: %d", total));
 895                 ip6->ip6_plen = 0;
 896                 REASON_SET(reason, PFRES_SHORT);
 897                 /* PF_DROP requires a valid mbuf *m0 in pf_test6(). */
 898                 return (PF_DROP);
 899         }
 900
 901         DPFPRINTF(("complete: %p(%d)", m, ntohs(ip6->ip6_plen)));
 902         return (PF_PASS);
 903
 904 fail:
 905         REASON_SET(reason, PFRES_MEMORY);
 906         /* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */
 907         return (PF_DROP);
 908 }
 909 #endif  /* INET6 */
 910
 911 #ifdef INET6
 912 int
 913 pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag)
 914 {
 915         struct mbuf             *m = *m0, *t;
 916         struct pf_fragment_tag  *ftag = (struct pf_fragment_tag *)(mtag + 1);
 917         struct pf_pdesc          pd;
 918         uint32_t                 frag_id;
 919         uint16_t                 hdrlen, extoff, maxlen;
 920         uint8_t                  proto;
 921         int                      error, action;
 922
 923         hdrlen = ftag->ft_hdrlen;
 924         extoff = ftag->ft_extoff;
 925         maxlen = ftag->ft_maxlen;
 926         frag_id = ftag->ft_id;
 927         m_tag_delete(m, mtag);
 928         mtag = NULL;
 929         ftag = NULL;
 930
 931         if (extoff) {
 932                 int off;
 933
 934                 /* Use protocol from next field of last extension header */
 935                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
 936                     &off);
 937                 KASSERT((m != NULL), ("pf_refragment6: short mbuf chain"));
 938                 proto = *(mtod(m, caddr_t) + off);
 939                 *(mtod(m, char *) + off) = IPPROTO_FRAGMENT;
 940                 m = *m0;
 941         } else {
 942                 struct ip6_hdr *hdr;
 943
 944                 hdr = mtod(m, struct ip6_hdr *);
 945                 proto = hdr->ip6_nxt;
 946                 hdr->ip6_nxt = IPPROTO_FRAGMENT;
 947         }
 948
 949         /* The MTU must be a multiple of 8 bytes, or we risk doing the
 950          * fragmentation wrong. */
 951         maxlen = maxlen & ~7;
 952
 953         /*
 954          * Maxlen may be less than 8 if there was only a single
 955          * fragment.  As it was fragmented before, add a fragment
 956          * header also for a single fragment.  If total or maxlen
 957          * is less than 8, ip6_fragment() will return EMSGSIZE and
 958          * we drop the packet.
 959          */
 960         error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id);
 961         m = (*m0)->m_nextpkt;
 962         (*m0)->m_nextpkt = NULL;
 963         if (error == 0) {
 964                 /* The first mbuf contains the unfragmented packet. */
 965                 m_freem(*m0);
 966                 *m0 = NULL;
 967                 action = PF_PASS;
 968         } else {
 969                 /* Drop expects an mbuf to free. */
 970                 DPFPRINTF(("refragment error %d", error));
 971                 action = PF_DROP;
 972         }
 973         for (t = m; m; m = t) {
 974                 t = m->m_nextpkt;
 975                 m->m_nextpkt = NULL;
 976                 m->m_flags |= M_SKIP_FIREWALL;
 977                 memset(&pd, 0, sizeof(pd));
 978                 pd.pf_mtag = pf_find_mtag(m);
 979                 if (error == 0)
 980                         ip6_forward(m, 0);
 981                 else
 982                         m_freem(m);
 983         }
 984
 985         return (action);
 986 }
 987 #endif /* INET6 */
 988
 989 #ifdef INET
 990 int
 991 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason,
 992     struct pf_pdesc *pd)
 993 {
 994         struct mbuf             *m = *m0;
 995         struct pf_rule          *r;
 996         struct ip               *h = mtod(m, struct ip *);
 997         int                      mff = (ntohs(h->ip_off) & IP_MF);
 998         int                      hlen = h->ip_hl << 2;
 999         u_int16_t                fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
1000         u_int16_t                max;
1001         int                      ip_len;
1002         int                      ip_off;
1003         int                      tag = -1;
1004         int                      verdict;
1005
1006         PF_RULES_RASSERT();
1007
1008         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1009         while (r != NULL) {
1010                 r->evaluations++;
1011                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1012                         r = r->skip[PF_SKIP_IFP].ptr;
1013                 else if (r->direction && r->direction != dir)
1014                         r = r->skip[PF_SKIP_DIR].ptr;
1015                 else if (r->af && r->af != AF_INET)
1016                         r = r->skip[PF_SKIP_AF].ptr;
1017                 else if (r->proto && r->proto != h->ip_p)
1018                         r = r->skip[PF_SKIP_PROTO].ptr;
1019                 else if (PF_MISMATCHAW(&r->src.addr,
1020                     (struct pf_addr *)&h->ip_src.s_addr, AF_INET,
1021                     r->src.neg, kif, M_GETFIB(m)))
1022                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1023                 else if (PF_MISMATCHAW(&r->dst.addr,
1024                     (struct pf_addr *)&h->ip_dst.s_addr, AF_INET,
1025                     r->dst.neg, NULL, M_GETFIB(m)))
1026                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1027                 else if (r->match_tag && !pf_match_tag(m, r, &tag,
1028                     pd->pf_mtag ? pd->pf_mtag->tag : 0))
1029                         r = TAILQ_NEXT(r, entries);
1030                 else
1031                         break;
1032         }
1033
1034         if (r == NULL || r->action == PF_NOSCRUB)
1035                 return (PF_PASS);
1036         else {
1037                 r->packets[dir == PF_OUT]++;
1038                 r->bytes[dir == PF_OUT] += pd->tot_len;
1039         }
1040
1041         /* Check for illegal packets */
1042         if (hlen < (int)sizeof(struct ip)) {
1043                 REASON_SET(reason, PFRES_NORM);
1044                 goto drop;
1045         }
1046
1047         if (hlen > ntohs(h->ip_len)) {
1048                 REASON_SET(reason, PFRES_NORM);
1049                 goto drop;
1050         }
1051
1052         /* Clear IP_DF if the rule uses the no-df option */
1053         if (r->rule_flag & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
1054                 u_int16_t ip_off = h->ip_off;
1055
1056                 h->ip_off &= htons(~IP_DF);
1057                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1058         }
1059
1060         /* We will need other tests here */
1061         if (!fragoff && !mff)
1062                 goto no_fragment;
1063
1064         /* We're dealing with a fragment now. Don't allow fragments
1065          * with IP_DF to enter the cache. If the flag was cleared by
1066          * no-df above, fine. Otherwise drop it.
1067          */
1068         if (h->ip_off & htons(IP_DF)) {
1069                 DPFPRINTF(("IP_DF\n"));
1070                 goto bad;
1071         }
1072
1073         ip_len = ntohs(h->ip_len) - hlen;
1074         ip_off = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
1075
1076         /* All fragments are 8 byte aligned */
1077         if (mff && (ip_len & 0x7)) {
1078                 DPFPRINTF(("mff and %d\n", ip_len));
1079                 goto bad;
1080         }
1081
1082         /* Respect maximum length */
1083         if (fragoff + ip_len > IP_MAXPACKET) {
1084                 DPFPRINTF(("max packet %d\n", fragoff + ip_len));
1085                 goto bad;
1086         }
1087         max = fragoff + ip_len;
1088
1089         /* Fully buffer all of the fragments
1090          * Might return a completely reassembled mbuf, or NULL */
1091         PF_FRAG_LOCK();
1092         DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
1093         verdict = pf_reassemble(m0, h, dir, reason);
1094         PF_FRAG_UNLOCK();
1095
1096         if (verdict != PF_PASS)
1097                 return (PF_DROP);
1098
1099         m = *m0;
1100         if (m == NULL)
1101                 return (PF_DROP);
1102
1103         h = mtod(m, struct ip *);
1104
1105  no_fragment:
1106         /* At this point, only IP_DF is allowed in ip_off */
1107         if (h->ip_off & ~htons(IP_DF)) {
1108                 u_int16_t ip_off = h->ip_off;
1109
1110                 h->ip_off &= htons(IP_DF);
1111                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1112         }
1113
1114         pf_scrub_ip(&m, r->rule_flag, r->min_ttl, r->set_tos);
1115
1116         return (PF_PASS);
1117
1118  bad:
1119         DPFPRINTF(("dropping bad fragment\n"));
1120         REASON_SET(reason, PFRES_FRAG);
1121  drop:
1122         if (r != NULL && r->log)
1123                 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
1124                     1);
1125
1126         return (PF_DROP);
1127 }
1128 #endif
1129
1130 #ifdef INET6
1131 int
1132 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif,
1133     u_short *reason, struct pf_pdesc *pd)
1134 {
1135         struct mbuf             *m = *m0;
1136         struct pf_rule          *r;
1137         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
1138         int                      extoff;
1139         int                      off;
1140         struct ip6_ext           ext;
1141         struct ip6_opt           opt;
1142         struct ip6_opt_jumbo     jumbo;
1143         struct ip6_frag          frag;
1144         u_int32_t                jumbolen = 0, 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         extoff = 0;
1189         off = sizeof(struct ip6_hdr);
1190         proto = h->ip6_nxt;
1191         terminal = 0;
1192         do {
1193                 switch (proto) {
1194                 case IPPROTO_FRAGMENT:
1195                         goto fragment;
1196                         break;
1197                 case IPPROTO_AH:
1198                 case IPPROTO_ROUTING:
1199                 case IPPROTO_DSTOPTS:
1200                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1201                             NULL, AF_INET6))
1202                                 goto shortpkt;
1203                         extoff = off;
1204                         if (proto == IPPROTO_AH)
1205                                 off += (ext.ip6e_len + 2) * 4;
1206                         else
1207                                 off += (ext.ip6e_len + 1) * 8;
1208                         proto = ext.ip6e_nxt;
1209                         break;
1210                 case IPPROTO_HOPOPTS:
1211                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1212                             NULL, AF_INET6))
1213                                 goto shortpkt;
1214                         extoff = off;
1215                         optend = off + (ext.ip6e_len + 1) * 8;
1216                         ooff = off + sizeof(ext);
1217                         do {
1218                                 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type,
1219                                     sizeof(opt.ip6o_type), NULL, NULL,
1220                                     AF_INET6))
1221                                         goto shortpkt;
1222                                 if (opt.ip6o_type == IP6OPT_PAD1) {
1223                                         ooff++;
1224                                         continue;
1225                                 }
1226                                 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt),
1227                                     NULL, NULL, AF_INET6))
1228                                         goto shortpkt;
1229                                 if (ooff + sizeof(opt) + opt.ip6o_len > optend)
1230                                         goto drop;
1231                                 switch (opt.ip6o_type) {
1232                                 case IP6OPT_JUMBO:
1233                                         if (h->ip6_plen != 0)
1234                                                 goto drop;
1235                                         if (!pf_pull_hdr(m, ooff, &jumbo,
1236                                             sizeof(jumbo), NULL, NULL,
1237                                             AF_INET6))
1238                                                 goto shortpkt;
1239                                         memcpy(&jumbolen, jumbo.ip6oj_jumbo_len,
1240                                             sizeof(jumbolen));
1241                                         jumbolen = ntohl(jumbolen);
1242                                         if (jumbolen <= IPV6_MAXPACKET)
1243                                                 goto drop;
1244                                         if (sizeof(struct ip6_hdr) + jumbolen !=
1245                                             m->m_pkthdr.len)
1246                                                 goto drop;
1247                                         break;
1248                                 default:
1249                                         break;
1250                                 }
1251                                 ooff += sizeof(opt) + opt.ip6o_len;
1252                         } while (ooff < optend);
1253
1254                         off = optend;
1255                         proto = ext.ip6e_nxt;
1256                         break;
1257                 default:
1258                         terminal = 1;
1259                         break;
1260                 }
1261         } while (!terminal);
1262
1263         /* jumbo payload option must be present, or plen > 0 */
1264         if (ntohs(h->ip6_plen) == 0)
1265                 plen = jumbolen;
1266         else
1267                 plen = ntohs(h->ip6_plen);
1268         if (plen == 0)
1269                 goto drop;
1270         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1271                 goto shortpkt;
1272
1273         pf_scrub_ip6(&m, r->min_ttl);
1274
1275         return (PF_PASS);
1276
1277  fragment:
1278         /* Jumbo payload packets cannot be fragmented. */
1279         plen = ntohs(h->ip6_plen);
1280         if (plen == 0 || jumbolen)
1281                 goto drop;
1282         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1283                 goto shortpkt;
1284
1285         if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6))
1286                 goto shortpkt;
1287
1288         /* Offset now points to data portion. */
1289         off += sizeof(frag);
1290
1291         /* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */
1292         if (pf_reassemble6(m0, h, &frag, off, extoff, reason) != PF_PASS)
1293                 return (PF_DROP);
1294         m = *m0;
1295         if (m == NULL)
1296                 return (PF_DROP);
1297
1298         pd->flags |= PFDESC_IP_REAS;
1299         return (PF_PASS);
1300
1301  shortpkt:
1302         REASON_SET(reason, PFRES_SHORT);
1303         if (r != NULL && r->log)
1304                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1305                     1);
1306         return (PF_DROP);
1307
1308  drop:
1309         REASON_SET(reason, PFRES_NORM);
1310         if (r != NULL && r->log)
1311                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1312                     1);
1313         return (PF_DROP);
1314 }
1315 #endif /* INET6 */
1316
1317 int
1318 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff,
1319     int off, void *h, struct pf_pdesc *pd)
1320 {
1321         struct pf_rule  *r, *rm = NULL;
1322         struct tcphdr   *th = pd->hdr.tcp;
1323         int              rewrite = 0;
1324         u_short          reason;
1325         u_int8_t         flags;
1326         sa_family_t      af = pd->af;
1327
1328         PF_RULES_RASSERT();
1329
1330         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1331         while (r != NULL) {
1332                 r->evaluations++;
1333                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1334                         r = r->skip[PF_SKIP_IFP].ptr;
1335                 else if (r->direction && r->direction != dir)
1336                         r = r->skip[PF_SKIP_DIR].ptr;
1337                 else if (r->af && r->af != af)
1338                         r = r->skip[PF_SKIP_AF].ptr;
1339                 else if (r->proto && r->proto != pd->proto)
1340                         r = r->skip[PF_SKIP_PROTO].ptr;
1341                 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af,
1342                     r->src.neg, kif, M_GETFIB(m)))
1343                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1344                 else if (r->src.port_op && !pf_match_port(r->src.port_op,
1345                             r->src.port[0], r->src.port[1], th->th_sport))
1346                         r = r->skip[PF_SKIP_SRC_PORT].ptr;
1347                 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af,
1348                     r->dst.neg, NULL, M_GETFIB(m)))
1349                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1350                 else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
1351                             r->dst.port[0], r->dst.port[1], th->th_dport))
1352                         r = r->skip[PF_SKIP_DST_PORT].ptr;
1353                 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match(
1354                             pf_osfp_fingerprint(pd, m, off, th),
1355                             r->os_fingerprint))
1356                         r = TAILQ_NEXT(r, entries);
1357                 else {
1358                         rm = r;
1359                         break;
1360                 }
1361         }
1362
1363         if (rm == NULL || rm->action == PF_NOSCRUB)
1364                 return (PF_PASS);
1365         else {
1366                 r->packets[dir == PF_OUT]++;
1367                 r->bytes[dir == PF_OUT] += pd->tot_len;
1368         }
1369
1370         if (rm->rule_flag & PFRULE_REASSEMBLE_TCP)
1371                 pd->flags |= PFDESC_TCP_NORM;
1372
1373         flags = th->th_flags;
1374         if (flags & TH_SYN) {
1375                 /* Illegal packet */
1376                 if (flags & TH_RST)
1377                         goto tcp_drop;
1378
1379                 if (flags & TH_FIN)
1380                         goto tcp_drop;
1381         } else {
1382                 /* Illegal packet */
1383                 if (!(flags & (TH_ACK|TH_RST)))
1384                         goto tcp_drop;
1385         }
1386
1387         if (!(flags & TH_ACK)) {
1388                 /* These flags are only valid if ACK is set */
1389                 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG))
1390                         goto tcp_drop;
1391         }
1392
1393         /* Check for illegal header length */
1394         if (th->th_off < (sizeof(struct tcphdr) >> 2))
1395                 goto tcp_drop;
1396
1397         /* If flags changed, or reserved data set, then adjust */
1398         if (flags != th->th_flags || th->th_x2 != 0) {
1399                 u_int16_t       ov, nv;
1400
1401                 ov = *(u_int16_t *)(&th->th_ack + 1);
1402                 th->th_flags = flags;
1403                 th->th_x2 = 0;
1404                 nv = *(u_int16_t *)(&th->th_ack + 1);
1405
1406                 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, ov, nv, 0);
1407                 rewrite = 1;
1408         }
1409
1410         /* Remove urgent pointer, if TH_URG is not set */
1411         if (!(flags & TH_URG) && th->th_urp) {
1412                 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, th->th_urp,
1413                     0, 0);
1414                 th->th_urp = 0;
1415                 rewrite = 1;
1416         }
1417
1418         /* Process options */
1419         if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af))
1420                 rewrite = 1;
1421
1422         /* copy back packet headers if we sanitized */
1423         if (rewrite)
1424                 m_copyback(m, off, sizeof(*th), (caddr_t)th);
1425
1426         return (PF_PASS);
1427
1428  tcp_drop:
1429         REASON_SET(&reason, PFRES_NORM);
1430         if (rm != NULL && r->log)
1431                 PFLOG_PACKET(kif, m, AF_INET, dir, reason, r, NULL, NULL, pd,
1432                     1);
1433         return (PF_DROP);
1434 }
1435
1436 int
1437 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd,
1438     struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst)
1439 {
1440         u_int32_t tsval, tsecr;
1441         u_int8_t hdr[60];
1442         u_int8_t *opt;
1443
1444         KASSERT((src->scrub == NULL),
1445             ("pf_normalize_tcp_init: src->scrub != NULL"));
1446
1447         src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT);
1448         if (src->scrub == NULL)
1449                 return (1);
1450
1451         switch (pd->af) {
1452 #ifdef INET
1453         case AF_INET: {
1454                 struct ip *h = mtod(m, struct ip *);
1455                 src->scrub->pfss_ttl = h->ip_ttl;
1456                 break;
1457         }
1458 #endif /* INET */
1459 #ifdef INET6
1460         case AF_INET6: {
1461                 struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1462                 src->scrub->pfss_ttl = h->ip6_hlim;
1463                 break;
1464         }
1465 #endif /* INET6 */
1466         }
1467
1468
1469         /*
1470          * All normalizations below are only begun if we see the start of
1471          * the connections.  They must all set an enabled bit in pfss_flags
1472          */
1473         if ((th->th_flags & TH_SYN) == 0)
1474                 return (0);
1475
1476
1477         if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub &&
1478             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1479                 /* Diddle with TCP options */
1480                 int hlen;
1481                 opt = hdr + sizeof(struct tcphdr);
1482                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1483                 while (hlen >= TCPOLEN_TIMESTAMP) {
1484                         switch (*opt) {
1485                         case TCPOPT_EOL:        /* FALLTHROUGH */
1486                         case TCPOPT_NOP:
1487                                 opt++;
1488                                 hlen--;
1489                                 break;
1490                         case TCPOPT_TIMESTAMP:
1491                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1492                                         src->scrub->pfss_flags |=
1493                                             PFSS_TIMESTAMP;
1494                                         src->scrub->pfss_ts_mod =
1495                                             htonl(arc4random());
1496
1497                                         /* note PFSS_PAWS not set yet */
1498                                         memcpy(&tsval, &opt[2],
1499                                             sizeof(u_int32_t));
1500                                         memcpy(&tsecr, &opt[6],
1501                                             sizeof(u_int32_t));
1502                                         src->scrub->pfss_tsval0 = ntohl(tsval);
1503                                         src->scrub->pfss_tsval = ntohl(tsval);
1504                                         src->scrub->pfss_tsecr = ntohl(tsecr);
1505                                         getmicrouptime(&src->scrub->pfss_last);
1506                                 }
1507                                 /* FALLTHROUGH */
1508                         default:
1509                                 hlen -= MAX(opt[1], 2);
1510                                 opt += MAX(opt[1], 2);
1511                                 break;
1512                         }
1513                 }
1514         }
1515
1516         return (0);
1517 }
1518
1519 void
1520 pf_normalize_tcp_cleanup(struct pf_state *state)
1521 {
1522         if (state->src.scrub)
1523                 uma_zfree(V_pf_state_scrub_z, state->src.scrub);
1524         if (state->dst.scrub)
1525                 uma_zfree(V_pf_state_scrub_z, state->dst.scrub);
1526
1527         /* Someday... flush the TCP segment reassembly descriptors. */
1528 }
1529
1530 int
1531 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd,
1532     u_short *reason, struct tcphdr *th, struct pf_state *state,
1533     struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback)
1534 {
1535         struct timeval uptime;
1536         u_int32_t tsval, tsecr;
1537         u_int tsval_from_last;
1538         u_int8_t hdr[60];
1539         u_int8_t *opt;
1540         int copyback = 0;
1541         int got_ts = 0;
1542
1543         KASSERT((src->scrub || dst->scrub),
1544             ("%s: src->scrub && dst->scrub!", __func__));
1545
1546         /*
1547          * Enforce the minimum TTL seen for this connection.  Negate a common
1548          * technique to evade an intrusion detection system and confuse
1549          * firewall state code.
1550          */
1551         switch (pd->af) {
1552 #ifdef INET
1553         case AF_INET: {
1554                 if (src->scrub) {
1555                         struct ip *h = mtod(m, struct ip *);
1556                         if (h->ip_ttl > src->scrub->pfss_ttl)
1557                                 src->scrub->pfss_ttl = h->ip_ttl;
1558                         h->ip_ttl = src->scrub->pfss_ttl;
1559                 }
1560                 break;
1561         }
1562 #endif /* INET */
1563 #ifdef INET6
1564         case AF_INET6: {
1565                 if (src->scrub) {
1566                         struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1567                         if (h->ip6_hlim > src->scrub->pfss_ttl)
1568                                 src->scrub->pfss_ttl = h->ip6_hlim;
1569                         h->ip6_hlim = src->scrub->pfss_ttl;
1570                 }
1571                 break;
1572         }
1573 #endif /* INET6 */
1574         }
1575
1576         if (th->th_off > (sizeof(struct tcphdr) >> 2) &&
1577             ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) ||
1578             (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) &&
1579             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1580                 /* Diddle with TCP options */
1581                 int hlen;
1582                 opt = hdr + sizeof(struct tcphdr);
1583                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1584                 while (hlen >= TCPOLEN_TIMESTAMP) {
1585                         switch (*opt) {
1586                         case TCPOPT_EOL:        /* FALLTHROUGH */
1587                         case TCPOPT_NOP:
1588                                 opt++;
1589                                 hlen--;
1590                                 break;
1591                         case TCPOPT_TIMESTAMP:
1592                                 /* Modulate the timestamps.  Can be used for
1593                                  * NAT detection, OS uptime determination or
1594                                  * reboot detection.
1595                                  */
1596
1597                                 if (got_ts) {
1598                                         /* Huh?  Multiple timestamps!? */
1599                                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1600                                                 DPFPRINTF(("multiple TS??"));
1601                                                 pf_print_state(state);
1602                                                 printf("\n");
1603                                         }
1604                                         REASON_SET(reason, PFRES_TS);
1605                                         return (PF_DROP);
1606                                 }
1607                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1608                                         memcpy(&tsval, &opt[2],
1609                                             sizeof(u_int32_t));
1610                                         if (tsval && src->scrub &&
1611                                             (src->scrub->pfss_flags &
1612                                             PFSS_TIMESTAMP)) {
1613                                                 tsval = ntohl(tsval);
1614                                                 pf_change_proto_a(m, &opt[2],
1615                                                     &th->th_sum,
1616                                                     htonl(tsval +
1617                                                     src->scrub->pfss_ts_mod),
1618                                                     0);
1619                                                 copyback = 1;
1620                                         }
1621
1622                                         /* Modulate TS reply iff valid (!0) */
1623                                         memcpy(&tsecr, &opt[6],
1624                                             sizeof(u_int32_t));
1625                                         if (tsecr && dst->scrub &&
1626                                             (dst->scrub->pfss_flags &
1627                                             PFSS_TIMESTAMP)) {
1628                                                 tsecr = ntohl(tsecr)
1629                                                     - dst->scrub->pfss_ts_mod;
1630                                                 pf_change_proto_a(m, &opt[6],
1631                                                     &th->th_sum, htonl(tsecr),
1632                                                     0);
1633                                                 copyback = 1;
1634                                         }
1635                                         got_ts = 1;
1636                                 }
1637                                 /* FALLTHROUGH */
1638                         default:
1639                                 hlen -= MAX(opt[1], 2);
1640                                 opt += MAX(opt[1], 2);
1641                                 break;
1642                         }
1643                 }
1644                 if (copyback) {
1645                         /* Copyback the options, caller copys back header */
1646                         *writeback = 1;
1647                         m_copyback(m, off + sizeof(struct tcphdr),
1648                             (th->th_off << 2) - sizeof(struct tcphdr), hdr +
1649                             sizeof(struct tcphdr));
1650                 }
1651         }
1652
1653
1654         /*
1655          * Must invalidate PAWS checks on connections idle for too long.
1656          * The fastest allowed timestamp clock is 1ms.  That turns out to
1657          * be about 24 days before it wraps.  XXX Right now our lowerbound
1658          * TS echo check only works for the first 12 days of a connection
1659          * when the TS has exhausted half its 32bit space
1660          */
1661 #define TS_MAX_IDLE     (24*24*60*60)
1662 #define TS_MAX_CONN     (12*24*60*60)   /* XXX remove when better tsecr check */
1663
1664         getmicrouptime(&uptime);
1665         if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) &&
1666             (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE ||
1667             time_uptime - state->creation > TS_MAX_CONN))  {
1668                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1669                         DPFPRINTF(("src idled out of PAWS\n"));
1670                         pf_print_state(state);
1671                         printf("\n");
1672                 }
1673                 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS)
1674                     | PFSS_PAWS_IDLED;
1675         }
1676         if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) &&
1677             uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) {
1678                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1679                         DPFPRINTF(("dst idled out of PAWS\n"));
1680                         pf_print_state(state);
1681                         printf("\n");
1682                 }
1683                 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS)
1684                     | PFSS_PAWS_IDLED;
1685         }
1686
1687         if (got_ts && src->scrub && dst->scrub &&
1688             (src->scrub->pfss_flags & PFSS_PAWS) &&
1689             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1690                 /* Validate that the timestamps are "in-window".
1691                  * RFC1323 describes TCP Timestamp options that allow
1692                  * measurement of RTT (round trip time) and PAWS
1693                  * (protection against wrapped sequence numbers).  PAWS
1694                  * gives us a set of rules for rejecting packets on
1695                  * long fat pipes (packets that were somehow delayed
1696                  * in transit longer than the time it took to send the
1697                  * full TCP sequence space of 4Gb).  We can use these
1698                  * rules and infer a few others that will let us treat
1699                  * the 32bit timestamp and the 32bit echoed timestamp
1700                  * as sequence numbers to prevent a blind attacker from
1701                  * inserting packets into a connection.
1702                  *
1703                  * RFC1323 tells us:
1704                  *  - The timestamp on this packet must be greater than
1705                  *    or equal to the last value echoed by the other
1706                  *    endpoint.  The RFC says those will be discarded
1707                  *    since it is a dup that has already been acked.
1708                  *    This gives us a lowerbound on the timestamp.
1709                  *        timestamp >= other last echoed timestamp
1710                  *  - The timestamp will be less than or equal to
1711                  *    the last timestamp plus the time between the
1712                  *    last packet and now.  The RFC defines the max
1713                  *    clock rate as 1ms.  We will allow clocks to be
1714                  *    up to 10% fast and will allow a total difference
1715                  *    or 30 seconds due to a route change.  And this
1716                  *    gives us an upperbound on the timestamp.
1717                  *        timestamp <= last timestamp + max ticks
1718                  *    We have to be careful here.  Windows will send an
1719                  *    initial timestamp of zero and then initialize it
1720                  *    to a random value after the 3whs; presumably to
1721                  *    avoid a DoS by having to call an expensive RNG
1722                  *    during a SYN flood.  Proof MS has at least one
1723                  *    good security geek.
1724                  *
1725                  *  - The TCP timestamp option must also echo the other
1726                  *    endpoints timestamp.  The timestamp echoed is the
1727                  *    one carried on the earliest unacknowledged segment
1728                  *    on the left edge of the sequence window.  The RFC
1729                  *    states that the host will reject any echoed
1730                  *    timestamps that were larger than any ever sent.
1731                  *    This gives us an upperbound on the TS echo.
1732                  *        tescr <= largest_tsval
1733                  *  - The lowerbound on the TS echo is a little more
1734                  *    tricky to determine.  The other endpoint's echoed
1735                  *    values will not decrease.  But there may be
1736                  *    network conditions that re-order packets and
1737                  *    cause our view of them to decrease.  For now the
1738                  *    only lowerbound we can safely determine is that
1739                  *    the TS echo will never be less than the original
1740                  *    TS.  XXX There is probably a better lowerbound.
1741                  *    Remove TS_MAX_CONN with better lowerbound check.
1742                  *        tescr >= other original TS
1743                  *
1744                  * It is also important to note that the fastest
1745                  * timestamp clock of 1ms will wrap its 32bit space in
1746                  * 24 days.  So we just disable TS checking after 24
1747                  * days of idle time.  We actually must use a 12d
1748                  * connection limit until we can come up with a better
1749                  * lowerbound to the TS echo check.
1750                  */
1751                 struct timeval delta_ts;
1752                 int ts_fudge;
1753
1754
1755                 /*
1756                  * PFTM_TS_DIFF is how many seconds of leeway to allow
1757                  * a host's timestamp.  This can happen if the previous
1758                  * packet got delayed in transit for much longer than
1759                  * this packet.
1760                  */
1761                 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0)
1762                         ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF];
1763
1764                 /* Calculate max ticks since the last timestamp */
1765 #define TS_MAXFREQ      1100            /* RFC max TS freq of 1Khz + 10% skew */
1766 #define TS_MICROSECS    1000000         /* microseconds per second */
1767                 delta_ts = uptime;
1768                 timevalsub(&delta_ts, &src->scrub->pfss_last);
1769                 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ;
1770                 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ);
1771
1772                 if ((src->state >= TCPS_ESTABLISHED &&
1773                     dst->state >= TCPS_ESTABLISHED) &&
1774                     (SEQ_LT(tsval, dst->scrub->pfss_tsecr) ||
1775                     SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) ||
1776                     (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) ||
1777                     SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) {
1778                         /* Bad RFC1323 implementation or an insertion attack.
1779                          *
1780                          * - Solaris 2.6 and 2.7 are known to send another ACK
1781                          *   after the FIN,FIN|ACK,ACK closing that carries
1782                          *   an old timestamp.
1783                          */
1784
1785                         DPFPRINTF(("Timestamp failed %c%c%c%c\n",
1786                             SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ',
1787                             SEQ_GT(tsval, src->scrub->pfss_tsval +
1788                             tsval_from_last) ? '1' : ' ',
1789                             SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ',
1790                             SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' '));
1791                         DPFPRINTF((" tsval: %u  tsecr: %u  +ticks: %u  "
1792                             "idle: %jus %lums\n",
1793                             tsval, tsecr, tsval_from_last,
1794                             (uintmax_t)delta_ts.tv_sec,
1795                             delta_ts.tv_usec / 1000));
1796                         DPFPRINTF((" src->tsval: %u  tsecr: %u\n",
1797                             src->scrub->pfss_tsval, src->scrub->pfss_tsecr));
1798                         DPFPRINTF((" dst->tsval: %u  tsecr: %u  tsval0: %u"
1799                             "\n", dst->scrub->pfss_tsval,
1800                             dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0));
1801                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1802                                 pf_print_state(state);
1803                                 pf_print_flags(th->th_flags);
1804                                 printf("\n");
1805                         }
1806                         REASON_SET(reason, PFRES_TS);
1807                         return (PF_DROP);
1808                 }
1809
1810                 /* XXX I'd really like to require tsecr but it's optional */
1811
1812         } else if (!got_ts && (th->th_flags & TH_RST) == 0 &&
1813             ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED)
1814             || pd->p_len > 0 || (th->th_flags & TH_SYN)) &&
1815             src->scrub && dst->scrub &&
1816             (src->scrub->pfss_flags & PFSS_PAWS) &&
1817             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1818                 /* Didn't send a timestamp.  Timestamps aren't really useful
1819                  * when:
1820                  *  - connection opening or closing (often not even sent).
1821                  *    but we must not let an attacker to put a FIN on a
1822                  *    data packet to sneak it through our ESTABLISHED check.
1823                  *  - on a TCP reset.  RFC suggests not even looking at TS.
1824                  *  - on an empty ACK.  The TS will not be echoed so it will
1825                  *    probably not help keep the RTT calculation in sync and
1826                  *    there isn't as much danger when the sequence numbers
1827                  *    got wrapped.  So some stacks don't include TS on empty
1828                  *    ACKs :-(
1829                  *
1830                  * To minimize the disruption to mostly RFC1323 conformant
1831                  * stacks, we will only require timestamps on data packets.
1832                  *
1833                  * And what do ya know, we cannot require timestamps on data
1834                  * packets.  There appear to be devices that do legitimate
1835                  * TCP connection hijacking.  There are HTTP devices that allow
1836                  * a 3whs (with timestamps) and then buffer the HTTP request.
1837                  * If the intermediate device has the HTTP response cache, it
1838                  * will spoof the response but not bother timestamping its
1839                  * packets.  So we can look for the presence of a timestamp in
1840                  * the first data packet and if there, require it in all future
1841                  * packets.
1842                  */
1843
1844                 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) {
1845                         /*
1846                          * Hey!  Someone tried to sneak a packet in.  Or the
1847                          * stack changed its RFC1323 behavior?!?!
1848                          */
1849                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1850                                 DPFPRINTF(("Did not receive expected RFC1323 "
1851                                     "timestamp\n"));
1852                                 pf_print_state(state);
1853                                 pf_print_flags(th->th_flags);
1854                                 printf("\n");
1855                         }
1856                         REASON_SET(reason, PFRES_TS);
1857                         return (PF_DROP);
1858                 }
1859         }
1860
1861
1862         /*
1863          * We will note if a host sends his data packets with or without
1864          * timestamps.  And require all data packets to contain a timestamp
1865          * if the first does.  PAWS implicitly requires that all data packets be
1866          * timestamped.  But I think there are middle-man devices that hijack
1867          * TCP streams immediately after the 3whs and don't timestamp their
1868          * packets (seen in a WWW accelerator or cache).
1869          */
1870         if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags &
1871             (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) {
1872                 if (got_ts)
1873                         src->scrub->pfss_flags |= PFSS_DATA_TS;
1874                 else {
1875                         src->scrub->pfss_flags |= PFSS_DATA_NOTS;
1876                         if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub &&
1877                             (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) {
1878                                 /* Don't warn if other host rejected RFC1323 */
1879                                 DPFPRINTF(("Broken RFC1323 stack did not "
1880                                     "timestamp data packet. Disabled PAWS "
1881                                     "security.\n"));
1882                                 pf_print_state(state);
1883                                 pf_print_flags(th->th_flags);
1884                                 printf("\n");
1885                         }
1886                 }
1887         }
1888
1889
1890         /*
1891          * Update PAWS values
1892          */
1893         if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags &
1894             (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) {
1895                 getmicrouptime(&src->scrub->pfss_last);
1896                 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) ||
1897                     (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1898                         src->scrub->pfss_tsval = tsval;
1899
1900                 if (tsecr) {
1901                         if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) ||
1902                             (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1903                                 src->scrub->pfss_tsecr = tsecr;
1904
1905                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 &&
1906                             (SEQ_LT(tsval, src->scrub->pfss_tsval0) ||
1907                             src->scrub->pfss_tsval0 == 0)) {
1908                                 /* tsval0 MUST be the lowest timestamp */
1909                                 src->scrub->pfss_tsval0 = tsval;
1910                         }
1911
1912                         /* Only fully initialized after a TS gets echoed */
1913                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0)
1914                                 src->scrub->pfss_flags |= PFSS_PAWS;
1915                 }
1916         }
1917
1918         /* I have a dream....  TCP segment reassembly.... */
1919         return (0);
1920 }
1921
1922 static int
1923 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th,
1924     int off, sa_family_t af)
1925 {
1926         u_int16_t       *mss;
1927         int              thoff;
1928         int              opt, cnt, optlen = 0;
1929         int              rewrite = 0;
1930         u_char           opts[TCP_MAXOLEN];
1931         u_char          *optp = opts;
1932
1933         thoff = th->th_off << 2;
1934         cnt = thoff - sizeof(struct tcphdr);
1935
1936         if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt,
1937             NULL, NULL, af))
1938                 return (rewrite);
1939
1940         for (; cnt > 0; cnt -= optlen, optp += optlen) {
1941                 opt = optp[0];
1942                 if (opt == TCPOPT_EOL)
1943                         break;
1944                 if (opt == TCPOPT_NOP)
1945                         optlen = 1;
1946                 else {
1947                         if (cnt < 2)
1948                                 break;
1949                         optlen = optp[1];
1950                         if (optlen < 2 || optlen > cnt)
1951                                 break;
1952                 }
1953                 switch (opt) {
1954                 case TCPOPT_MAXSEG:
1955                         mss = (u_int16_t *)(optp + 2);
1956                         if ((ntohs(*mss)) > r->max_mss) {
1957                                 th->th_sum = pf_proto_cksum_fixup(m,
1958                                     th->th_sum, *mss, htons(r->max_mss), 0);
1959                                 *mss = htons(r->max_mss);
1960                                 rewrite = 1;
1961                         }
1962                         break;
1963                 default:
1964                         break;
1965                 }
1966         }
1967
1968         if (rewrite)
1969                 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts);
1970
1971         return (rewrite);
1972 }
1973
1974 #ifdef INET
1975 static void
1976 pf_scrub_ip(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos)
1977 {
1978         struct mbuf             *m = *m0;
1979         struct ip               *h = mtod(m, struct ip *);
1980
1981         /* Clear IP_DF if no-df was requested */
1982         if (flags & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
1983                 u_int16_t ip_off = h->ip_off;
1984
1985                 h->ip_off &= htons(~IP_DF);
1986                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1987         }
1988
1989         /* Enforce a minimum ttl, may cause endless packet loops */
1990         if (min_ttl && h->ip_ttl < min_ttl) {
1991                 u_int16_t ip_ttl = h->ip_ttl;
1992
1993                 h->ip_ttl = min_ttl;
1994                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
1995         }
1996
1997         /* Enforce tos */
1998         if (flags & PFRULE_SET_TOS) {
1999                 u_int16_t       ov, nv;
2000
2001                 ov = *(u_int16_t *)h;
2002                 h->ip_tos = tos | (h->ip_tos & IPTOS_ECN_MASK);
2003                 nv = *(u_int16_t *)h;
2004
2005                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0);
2006         }
2007
2008         /* random-id, but not for fragments */
2009         if (flags & PFRULE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) {
2010                 uint16_t ip_id = h->ip_id;
2011
2012                 ip_fillid(h);
2013                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0);
2014         }
2015 }
2016 #endif /* INET */
2017
2018 #ifdef INET6
2019 static void
2020 pf_scrub_ip6(struct mbuf **m0, u_int8_t min_ttl)
2021 {
2022         struct mbuf             *m = *m0;
2023         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
2024
2025         /* Enforce a minimum ttl, may cause endless packet loops */
2026         if (min_ttl && h->ip6_hlim < min_ttl)
2027                 h->ip6_hlim = min_ttl;
2028 }
2029 #endif