sys/netpfil/pf/pf_norm.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause
   3  *
   4  * Copyright 2001 Niels Provos <provos@citi.umich.edu>
   5  * Copyright 2011-2018 Alexander Bluhm <bluhm@openbsd.org>
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  *
  28  *      $OpenBSD: pf_norm.c,v 1.114 2009/01/29 14:11:45 henning Exp $
  29  */
  30
  31 #include <sys/cdefs.h>
  32 __FBSDID("$FreeBSD$");
  33
  34 #include "opt_inet.h"
  35 #include "opt_inet6.h"
  36 #include "opt_pf.h"
  37
  38 #include <sys/param.h>
  39 #include <sys/kernel.h>
  40 #include <sys/lock.h>
  41 #include <sys/mbuf.h>
  42 #include <sys/mutex.h>
  43 #include <sys/refcount.h>
  44 #include <sys/socket.h>
  45
  46 #include <net/if.h>
  47 #include <net/vnet.h>
  48 #include <net/pfvar.h>
  49 #include <net/if_pflog.h>
  50
  51 #include <netinet/in.h>
  52 #include <netinet/ip.h>
  53 #include <netinet/ip_var.h>
  54 #include <netinet6/ip6_var.h>
  55 #include <netinet6/scope6_var.h>
  56 #include <netinet/tcp.h>
  57 #include <netinet/tcp_fsm.h>
  58 #include <netinet/tcp_seq.h>
  59
  60 #ifdef INET6
  61 #include <netinet/ip6.h>
  62 #endif /* INET6 */
  63
  64 struct pf_frent {
  65         TAILQ_ENTRY(pf_frent)   fr_next;
  66         struct mbuf     *fe_m;
  67         uint16_t        fe_hdrlen;      /* ipv4 header length with ip options
  68                                            ipv6, extension, fragment header */
  69         uint16_t        fe_extoff;      /* last extension header offset or 0 */
  70         uint16_t        fe_len;         /* fragment length */
  71         uint16_t        fe_off;         /* fragment offset */
  72         uint16_t        fe_mff;         /* more fragment flag */
  73 };
  74
  75 struct pf_fragment_cmp {
  76         struct pf_addr  frc_src;
  77         struct pf_addr  frc_dst;
  78         uint32_t        frc_id;
  79         sa_family_t     frc_af;
  80         uint8_t         frc_proto;
  81 };
  82
  83 struct pf_fragment {
  84         struct pf_fragment_cmp  fr_key;
  85 #define fr_src  fr_key.frc_src
  86 #define fr_dst  fr_key.frc_dst
  87 #define fr_id   fr_key.frc_id
  88 #define fr_af   fr_key.frc_af
  89 #define fr_proto        fr_key.frc_proto
  90
  91         /* pointers to queue element */
  92         struct pf_frent *fr_firstoff[PF_FRAG_ENTRY_POINTS];
  93         /* count entries between pointers */
  94         uint8_t fr_entries[PF_FRAG_ENTRY_POINTS];
  95         RB_ENTRY(pf_fragment) fr_entry;
  96         TAILQ_ENTRY(pf_fragment) frag_next;
  97         uint32_t        fr_timeout;
  98         uint16_t        fr_maxlen;      /* maximum length of single fragment */
  99         u_int16_t       fr_holes;       /* number of holes in the queue */
 100         TAILQ_HEAD(pf_fragq, pf_frent) fr_queue;
 101 };
 102
 103 struct pf_fragment_tag {
 104         uint16_t        ft_hdrlen;      /* header length of reassembled pkt */
 105         uint16_t        ft_extoff;      /* last extension header offset or 0 */
 106         uint16_t        ft_maxlen;      /* maximum fragment payload length */
 107         uint32_t        ft_id;          /* fragment id */
 108 };
 109
 110 VNET_DEFINE_STATIC(struct mtx, pf_frag_mtx);
 111 #define V_pf_frag_mtx           VNET(pf_frag_mtx)
 112 #define PF_FRAG_LOCK()          mtx_lock(&V_pf_frag_mtx)
 113 #define PF_FRAG_UNLOCK()        mtx_unlock(&V_pf_frag_mtx)
 114 #define PF_FRAG_ASSERT()        mtx_assert(&V_pf_frag_mtx, MA_OWNED)
 115
 116 VNET_DEFINE(uma_zone_t, pf_state_scrub_z);      /* XXX: shared with pfsync */
 117
 118 VNET_DEFINE_STATIC(uma_zone_t, pf_frent_z);
 119 #define V_pf_frent_z    VNET(pf_frent_z)
 120 VNET_DEFINE_STATIC(uma_zone_t, pf_frag_z);
 121 #define V_pf_frag_z     VNET(pf_frag_z)
 122
 123 TAILQ_HEAD(pf_fragqueue, pf_fragment);
 124 TAILQ_HEAD(pf_cachequeue, pf_fragment);
 125 VNET_DEFINE_STATIC(struct pf_fragqueue, pf_fragqueue);
 126 #define V_pf_fragqueue                  VNET(pf_fragqueue)
 127 RB_HEAD(pf_frag_tree, pf_fragment);
 128 VNET_DEFINE_STATIC(struct pf_frag_tree, pf_frag_tree);
 129 #define V_pf_frag_tree                  VNET(pf_frag_tree)
 130 static int               pf_frag_compare(struct pf_fragment *,
 131                             struct pf_fragment *);
 132 static RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 133 static RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 134
 135 static void     pf_flush_fragments(void);
 136 static void     pf_free_fragment(struct pf_fragment *);
 137 static void     pf_remove_fragment(struct pf_fragment *);
 138
 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 int      pf_reassemble(struct mbuf **, struct ip *, int, u_short *);
 155 #endif  /* INET */
 156 #ifdef INET6
 157 static int      pf_reassemble6(struct mbuf **, struct ip6_hdr *,
 158                     struct ip6_frag *, uint16_t, uint16_t, u_short *);
 159 #endif  /* INET6 */
 160
 161 #define DPFPRINTF(x) do {                               \
 162         if (V_pf_status.debug >= PF_DEBUG_MISC) {       \
 163                 printf("%s: ", __func__);               \
 164                 printf x ;                              \
 165         }                                               \
 166 } while(0)
 167
 168 #ifdef INET
 169 static void
 170 pf_ip2key(struct ip *ip, int dir, struct pf_fragment_cmp *key)
 171 {
 172
 173         key->frc_src.v4 = ip->ip_src;
 174         key->frc_dst.v4 = ip->ip_dst;
 175         key->frc_af = AF_INET;
 176         key->frc_proto = ip->ip_p;
 177         key->frc_id = ip->ip_id;
 178 }
 179 #endif  /* INET */
 180
 181 void
 182 pf_normalize_init(void)
 183 {
 184
 185         V_pf_frag_z = uma_zcreate("pf frags", sizeof(struct pf_fragment),
 186             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 187         V_pf_frent_z = uma_zcreate("pf frag entries", sizeof(struct pf_frent),
 188             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 189         V_pf_state_scrub_z = uma_zcreate("pf state scrubs",
 190             sizeof(struct pf_state_scrub),  NULL, NULL, NULL, NULL,
 191             UMA_ALIGN_PTR, 0);
 192
 193         mtx_init(&V_pf_frag_mtx, "pf fragments", NULL, MTX_DEF);
 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         mtx_destroy(&V_pf_frag_mtx);
 212 }
 213
 214 static int
 215 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b)
 216 {
 217         int     diff;
 218
 219         if ((diff = a->fr_id - b->fr_id) != 0)
 220                 return (diff);
 221         if ((diff = a->fr_proto - b->fr_proto) != 0)
 222                 return (diff);
 223         if ((diff = a->fr_af - b->fr_af) != 0)
 224                 return (diff);
 225         if ((diff = pf_addr_cmp(&a->fr_src, &b->fr_src, a->fr_af)) != 0)
 226                 return (diff);
 227         if ((diff = pf_addr_cmp(&a->fr_dst, &b->fr_dst, a->fr_af)) != 0)
 228                 return (diff);
 229         return (0);
 230 }
 231
 232 void
 233 pf_purge_expired_fragments(void)
 234 {
 235         u_int32_t       expire = time_uptime -
 236                             V_pf_default_rule.timeout[PFTM_FRAG];
 237
 238         pf_purge_fragments(expire);
 239 }
 240
 241 void
 242 pf_purge_fragments(uint32_t expire)
 243 {
 244         struct pf_fragment      *frag;
 245
 246         PF_FRAG_LOCK();
 247         while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) {
 248                 if (frag->fr_timeout > expire)
 249                         break;
 250
 251                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 252                 pf_free_fragment(frag);
 253         }
 254
 255         PF_FRAG_UNLOCK();
 256 }
 257
 258 /*
 259  * Try to flush old fragments to make space for new ones
 260  */
 261 static void
 262 pf_flush_fragments(void)
 263 {
 264         struct pf_fragment      *frag;
 265         int                      goal;
 266
 267         PF_FRAG_ASSERT();
 268
 269         goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10;
 270         DPFPRINTF(("trying to free %d frag entriess\n", goal));
 271         while (goal < uma_zone_get_cur(V_pf_frent_z)) {
 272                 frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue);
 273                 if (frag)
 274                         pf_free_fragment(frag);
 275                 else
 276                         break;
 277         }
 278 }
 279
 280 /* Frees the fragments and all associated entries */
 281 static void
 282 pf_free_fragment(struct pf_fragment *frag)
 283 {
 284         struct pf_frent         *frent;
 285
 286         PF_FRAG_ASSERT();
 287
 288         /* Free all fragments */
 289         for (frent = TAILQ_FIRST(&frag->fr_queue); frent;
 290             frent = TAILQ_FIRST(&frag->fr_queue)) {
 291                 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
 292
 293                 m_freem(frent->fe_m);
 294                 uma_zfree(V_pf_frent_z, frent);
 295         }
 296
 297         pf_remove_fragment(frag);
 298 }
 299
 300 static struct pf_fragment *
 301 pf_find_fragment(struct pf_fragment_cmp *key, struct pf_frag_tree *tree)
 302 {
 303         struct pf_fragment      *frag;
 304
 305         PF_FRAG_ASSERT();
 306
 307         frag = RB_FIND(pf_frag_tree, tree, (struct pf_fragment *)key);
 308         if (frag != NULL) {
 309                 /* XXX Are we sure we want to update the timeout? */
 310                 frag->fr_timeout = time_uptime;
 311                 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 312                 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
 313         }
 314
 315         return (frag);
 316 }
 317
 318 /* Removes a fragment from the fragment queue and frees the fragment */
 319 static void
 320 pf_remove_fragment(struct pf_fragment *frag)
 321 {
 322
 323         PF_FRAG_ASSERT();
 324         KASSERT(frag, ("frag != NULL"));
 325
 326         RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag);
 327         TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 328         uma_zfree(V_pf_frag_z, frag);
 329 }
 330
 331 static struct pf_frent *
 332 pf_create_fragment(u_short *reason)
 333 {
 334         struct pf_frent *frent;
 335
 336         PF_FRAG_ASSERT();
 337
 338         frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 339         if (frent == NULL) {
 340                 pf_flush_fragments();
 341                 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 342                 if (frent == NULL) {
 343                         REASON_SET(reason, PFRES_MEMORY);
 344                         return (NULL);
 345                 }
 346         }
 347
 348         return (frent);
 349 }
 350
 351 /*
 352  * Calculate the additional holes that were created in the fragment
 353  * queue by inserting this fragment.  A fragment in the middle
 354  * creates one more hole by splitting.  For each connected side,
 355  * it loses one hole.
 356  * Fragment entry must be in the queue when calling this function.
 357  */
 358 static int
 359 pf_frent_holes(struct pf_frent *frent)
 360 {
 361         struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next);
 362         struct pf_frent *next = TAILQ_NEXT(frent, fr_next);
 363         int holes = 1;
 364
 365         if (prev == NULL) {
 366                 if (frent->fe_off == 0)
 367                         holes--;
 368         } else {
 369                 KASSERT(frent->fe_off != 0, ("frent->fe_off != 0"));
 370                 if (frent->fe_off == prev->fe_off + prev->fe_len)
 371                         holes--;
 372         }
 373         if (next == NULL) {
 374                 if (!frent->fe_mff)
 375                         holes--;
 376         } else {
 377                 KASSERT(frent->fe_mff, ("frent->fe_mff"));
 378                 if (next->fe_off == frent->fe_off + frent->fe_len)
 379                         holes--;
 380         }
 381         return holes;
 382 }
 383
 384 static inline int
 385 pf_frent_index(struct pf_frent *frent)
 386 {
 387         /*
 388          * We have an array of 16 entry points to the queue.  A full size
 389          * 65535 octet IP packet can have 8192 fragments.  So the queue
 390          * traversal length is at most 512 and at most 16 entry points are
 391          * checked.  We need 128 additional bytes on a 64 bit architecture.
 392          */
 393         CTASSERT(((u_int16_t)0xffff &~ 7) / (0x10000 / PF_FRAG_ENTRY_POINTS) ==
 394             16 - 1);
 395         CTASSERT(((u_int16_t)0xffff >> 3) / PF_FRAG_ENTRY_POINTS == 512 - 1);
 396
 397         return frent->fe_off / (0x10000 / PF_FRAG_ENTRY_POINTS);
 398 }
 399
 400 static int
 401 pf_frent_insert(struct pf_fragment *frag, struct pf_frent *frent,
 402     struct pf_frent *prev)
 403 {
 404         int index;
 405
 406         CTASSERT(PF_FRAG_ENTRY_LIMIT <= 0xff);
 407
 408         /*
 409          * A packet has at most 65536 octets.  With 16 entry points, each one
 410          * spawns 4096 octets.  We limit these to 64 fragments each, which
 411          * means on average every fragment must have at least 64 octets.
 412          */
 413         index = pf_frent_index(frent);
 414         if (frag->fr_entries[index] >= PF_FRAG_ENTRY_LIMIT)
 415                 return ENOBUFS;
 416         frag->fr_entries[index]++;
 417
 418         if (prev == NULL) {
 419                 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next);
 420         } else {
 421                 KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off,
 422                     ("overlapping fragment"));
 423                 TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next);
 424         }
 425
 426         if (frag->fr_firstoff[index] == NULL) {
 427                 KASSERT(prev == NULL || pf_frent_index(prev) < index,
 428                     ("prev == NULL || pf_frent_index(pref) < index"));
 429                 frag->fr_firstoff[index] = frent;
 430         } else {
 431                 if (frent->fe_off < frag->fr_firstoff[index]->fe_off) {
 432                         KASSERT(prev == NULL || pf_frent_index(prev) < index,
 433                             ("prev == NULL || pf_frent_index(pref) < index"));
 434                         frag->fr_firstoff[index] = frent;
 435                 } else {
 436                         KASSERT(prev != NULL, ("prev != NULL"));
 437                         KASSERT(pf_frent_index(prev) == index,
 438                             ("pf_frent_index(prev) == index"));
 439                 }
 440         }
 441
 442         frag->fr_holes += pf_frent_holes(frent);
 443
 444         return 0;
 445 }
 446
 447 void
 448 pf_frent_remove(struct pf_fragment *frag, struct pf_frent *frent)
 449 {
 450 #ifdef INVARIANTS
 451         struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next);
 452 #endif
 453         struct pf_frent *next = TAILQ_NEXT(frent, fr_next);
 454         int index;
 455
 456         frag->fr_holes -= pf_frent_holes(frent);
 457
 458         index = pf_frent_index(frent);
 459         KASSERT(frag->fr_firstoff[index] != NULL, ("frent not found"));
 460         if (frag->fr_firstoff[index]->fe_off == frent->fe_off) {
 461                 if (next == NULL) {
 462                         frag->fr_firstoff[index] = NULL;
 463                 } else {
 464                         KASSERT(frent->fe_off + frent->fe_len <= next->fe_off,
 465                             ("overlapping fragment"));
 466                         if (pf_frent_index(next) == index) {
 467                                 frag->fr_firstoff[index] = next;
 468                         } else {
 469                                 frag->fr_firstoff[index] = NULL;
 470                         }
 471                 }
 472         } else {
 473                 KASSERT(frag->fr_firstoff[index]->fe_off < frent->fe_off,
 474                     ("frag->fr_firstoff[index]->fe_off < frent->fe_off"));
 475                 KASSERT(prev != NULL, ("prev != NULL"));
 476                 KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off,
 477                     ("overlapping fragment"));
 478                 KASSERT(pf_frent_index(prev) == index,
 479                     ("pf_frent_index(prev) == index"));
 480         }
 481
 482         TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
 483
 484         KASSERT(frag->fr_entries[index] > 0, ("No fragments remaining"));
 485         frag->fr_entries[index]--;
 486 }
 487
 488 struct pf_frent *
 489 pf_frent_previous(struct pf_fragment *frag, struct pf_frent *frent)
 490 {
 491         struct pf_frent *prev, *next;
 492         int index;
 493
 494         /*
 495          * If there are no fragments after frag, take the final one.  Assume
 496          * that the global queue is not empty.
 497          */
 498         prev = TAILQ_LAST(&frag->fr_queue, pf_fragq);
 499         KASSERT(prev != NULL, ("prev != NULL"));
 500         if (prev->fe_off <= frent->fe_off)
 501                 return prev;
 502         /*
 503          * We want to find a fragment entry that is before frag, but still
 504          * close to it.  Find the first fragment entry that is in the same
 505          * entry point or in the first entry point after that.  As we have
 506          * already checked that there are entries behind frag, this will
 507          * succeed.
 508          */
 509         for (index = pf_frent_index(frent); index < PF_FRAG_ENTRY_POINTS;
 510             index++) {
 511                 prev = frag->fr_firstoff[index];
 512                 if (prev != NULL)
 513                         break;
 514         }
 515         KASSERT(prev != NULL, ("prev != NULL"));
 516         /*
 517          * In prev we may have a fragment from the same entry point that is
 518          * before frent, or one that is just one position behind frent.
 519          * In the latter case, we go back one step and have the predecessor.
 520          * There may be none if the new fragment will be the first one.
 521          */
 522         if (prev->fe_off > frent->fe_off) {
 523                 prev = TAILQ_PREV(prev, pf_fragq, fr_next);
 524                 if (prev == NULL)
 525                         return NULL;
 526                 KASSERT(prev->fe_off <= frent->fe_off,
 527                     ("prev->fe_off <= frent->fe_off"));
 528                 return prev;
 529         }
 530         /*
 531          * In prev is the first fragment of the entry point.  The offset
 532          * of frag is behind it.  Find the closest previous fragment.
 533          */
 534         for (next = TAILQ_NEXT(prev, fr_next); next != NULL;
 535             next = TAILQ_NEXT(next, fr_next)) {
 536                 if (next->fe_off > frent->fe_off)
 537                         break;
 538                 prev = next;
 539         }
 540         return prev;
 541 }
 542
 543 static struct pf_fragment *
 544 pf_fillup_fragment(struct pf_fragment_cmp *key, struct pf_frent *frent,
 545     u_short *reason)
 546 {
 547         struct pf_frent         *after, *next, *prev;
 548         struct pf_fragment      *frag;
 549         uint16_t                total;
 550         int                     old_index, new_index;
 551
 552         PF_FRAG_ASSERT();
 553
 554         /* No empty fragments. */
 555         if (frent->fe_len == 0) {
 556                 DPFPRINTF(("bad fragment: len 0\n"));
 557                 goto bad_fragment;
 558         }
 559
 560         /* All fragments are 8 byte aligned. */
 561         if (frent->fe_mff && (frent->fe_len & 0x7)) {
 562                 DPFPRINTF(("bad fragment: mff and len %d\n", frent->fe_len));
 563                 goto bad_fragment;
 564         }
 565
 566         /* Respect maximum length, IP_MAXPACKET == IPV6_MAXPACKET. */
 567         if (frent->fe_off + frent->fe_len > IP_MAXPACKET) {
 568                 DPFPRINTF(("bad fragment: max packet %d\n",
 569                     frent->fe_off + frent->fe_len));
 570                 goto bad_fragment;
 571         }
 572
 573         DPFPRINTF((key->frc_af == AF_INET ?
 574             "reass frag %d @ %d-%d\n" : "reass frag %#08x @ %d-%d\n",
 575             key->frc_id, frent->fe_off, frent->fe_off + frent->fe_len));
 576
 577         /* Fully buffer all of the fragments in this fragment queue. */
 578         frag = pf_find_fragment(key, &V_pf_frag_tree);
 579
 580         /* Create a new reassembly queue for this packet. */
 581         if (frag == NULL) {
 582                 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 583                 if (frag == NULL) {
 584                         pf_flush_fragments();
 585                         frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 586                         if (frag == NULL) {
 587                                 REASON_SET(reason, PFRES_MEMORY);
 588                                 goto drop_fragment;
 589                         }
 590                 }
 591
 592                 *(struct pf_fragment_cmp *)frag = *key;
 593                 memset(frag->fr_firstoff, 0, sizeof(frag->fr_firstoff));
 594                 memset(frag->fr_entries, 0, sizeof(frag->fr_entries));
 595                 frag->fr_timeout = time_uptime;
 596                 frag->fr_maxlen = frent->fe_len;
 597                 frag->fr_holes = 1;
 598                 TAILQ_INIT(&frag->fr_queue);
 599
 600                 RB_INSERT(pf_frag_tree, &V_pf_frag_tree, frag);
 601                 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
 602
 603                 /* We do not have a previous fragment, cannot fail. */
 604                 pf_frent_insert(frag, frent, NULL);
 605
 606                 return (frag);
 607         }
 608
 609         KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue"));
 610
 611         /* Remember maximum fragment len for refragmentation. */
 612         if (frent->fe_len > frag->fr_maxlen)
 613                 frag->fr_maxlen = frent->fe_len;
 614
 615         /* Maximum data we have seen already. */
 616         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 617                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 618
 619         /* Non terminal fragments must have more fragments flag. */
 620         if (frent->fe_off + frent->fe_len < total && !frent->fe_mff)
 621                 goto bad_fragment;
 622
 623         /* Check if we saw the last fragment already. */
 624         if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) {
 625                 if (frent->fe_off + frent->fe_len > total ||
 626                     (frent->fe_off + frent->fe_len == total && frent->fe_mff))
 627                         goto bad_fragment;
 628         } else {
 629                 if (frent->fe_off + frent->fe_len == total && !frent->fe_mff)
 630                         goto bad_fragment;
 631         }
 632
 633         /* Find neighbors for newly inserted fragment */
 634         prev = pf_frent_previous(frag, frent);
 635         if (prev == NULL) {
 636                 after = TAILQ_FIRST(&frag->fr_queue);
 637                 KASSERT(after != NULL, ("after != NULL"));
 638         } else {
 639                 after = TAILQ_NEXT(prev, fr_next);
 640         }
 641
 642         if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) {
 643                 uint16_t precut;
 644
 645                 precut = prev->fe_off + prev->fe_len - frent->fe_off;
 646                 if (precut >= frent->fe_len)
 647                         goto bad_fragment;
 648                 DPFPRINTF(("overlap -%d\n", precut));
 649                 m_adj(frent->fe_m, precut);
 650                 frent->fe_off += precut;
 651                 frent->fe_len -= precut;
 652         }
 653
 654         for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off;
 655             after = next) {
 656                 uint16_t aftercut;
 657
 658                 aftercut = frent->fe_off + frent->fe_len - after->fe_off;
 659                 DPFPRINTF(("adjust overlap %d\n", aftercut));
 660                 if (aftercut < after->fe_len) {
 661                         m_adj(after->fe_m, aftercut);
 662                         old_index = pf_frent_index(after);
 663                         after->fe_off += aftercut;
 664                         after->fe_len -= aftercut;
 665                         new_index = pf_frent_index(after);
 666                         if (old_index != new_index) {
 667                                 DPFPRINTF(("frag index %d, new %d",
 668                                     old_index, new_index));
 669                                 /* Fragment switched queue as fe_off changed */
 670                                 after->fe_off -= aftercut;
 671                                 after->fe_len += aftercut;
 672                                 /* Remove restored fragment from old queue */
 673                                 pf_frent_remove(frag, after);
 674                                 after->fe_off += aftercut;
 675                                 after->fe_len -= aftercut;
 676                                 /* Insert into correct queue */
 677                                 if (pf_frent_insert(frag, after, prev)) {
 678                                         DPFPRINTF(
 679                                             ("fragment requeue limit exceeded"));
 680                                         m_freem(after->fe_m);
 681                                         uma_zfree(V_pf_frent_z, after);
 682                                         /* There is not way to recover */
 683                                         goto bad_fragment;
 684                                 }
 685                         }
 686                         break;
 687                 }
 688
 689                 /* This fragment is completely overlapped, lose it. */
 690                 next = TAILQ_NEXT(after, fr_next);
 691                 pf_frent_remove(frag, after);
 692                 m_freem(after->fe_m);
 693                 uma_zfree(V_pf_frent_z, after);
 694         }
 695
 696         /* If part of the queue gets too long, there is not way to recover. */
 697         if (pf_frent_insert(frag, frent, prev)) {
 698                 DPFPRINTF(("fragment queue limit exceeded\n"));
 699                 goto bad_fragment;
 700         }
 701
 702         return (frag);
 703
 704 bad_fragment:
 705         REASON_SET(reason, PFRES_FRAG);
 706 drop_fragment:
 707         uma_zfree(V_pf_frent_z, frent);
 708         return (NULL);
 709 }
 710
 711 static struct mbuf *
 712 pf_join_fragment(struct pf_fragment *frag)
 713 {
 714         struct mbuf *m, *m2;
 715         struct pf_frent *frent, *next;
 716
 717         frent = TAILQ_FIRST(&frag->fr_queue);
 718         next = TAILQ_NEXT(frent, fr_next);
 719
 720         m = frent->fe_m;
 721         m_adj(m, (frent->fe_hdrlen + frent->fe_len) - m->m_pkthdr.len);
 722         uma_zfree(V_pf_frent_z, frent);
 723         for (frent = next; frent != NULL; frent = next) {
 724                 next = TAILQ_NEXT(frent, fr_next);
 725
 726                 m2 = frent->fe_m;
 727                 /* Strip off ip header. */
 728                 m_adj(m2, frent->fe_hdrlen);
 729                 /* Strip off any trailing bytes. */
 730                 m_adj(m2, frent->fe_len - m2->m_pkthdr.len);
 731
 732                 uma_zfree(V_pf_frent_z, frent);
 733                 m_cat(m, m2);
 734         }
 735
 736         /* Remove from fragment queue. */
 737         pf_remove_fragment(frag);
 738
 739         return (m);
 740 }
 741
 742 #ifdef INET
 743 static int
 744 pf_reassemble(struct mbuf **m0, struct ip *ip, int dir, u_short *reason)
 745 {
 746         struct mbuf             *m = *m0;
 747         struct pf_frent         *frent;
 748         struct pf_fragment      *frag;
 749         struct pf_fragment_cmp  key;
 750         uint16_t                total, hdrlen;
 751
 752         /* Get an entry for the fragment queue */
 753         if ((frent = pf_create_fragment(reason)) == NULL)
 754                 return (PF_DROP);
 755
 756         frent->fe_m = m;
 757         frent->fe_hdrlen = ip->ip_hl << 2;
 758         frent->fe_extoff = 0;
 759         frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2);
 760         frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3;
 761         frent->fe_mff = ntohs(ip->ip_off) & IP_MF;
 762
 763         pf_ip2key(ip, dir, &key);
 764
 765         if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL)
 766                 return (PF_DROP);
 767
 768         /* The mbuf is part of the fragment entry, no direct free or access */
 769         m = *m0 = NULL;
 770
 771         if (frag->fr_holes) {
 772                 DPFPRINTF(("frag %d, holes %d\n", frag->fr_id, frag->fr_holes));
 773                 return (PF_PASS);  /* drop because *m0 is NULL, no error */
 774         }
 775
 776         /* We have all the data */
 777         frent = TAILQ_FIRST(&frag->fr_queue);
 778         KASSERT(frent != NULL, ("frent != NULL"));
 779         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 780                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 781         hdrlen = frent->fe_hdrlen;
 782
 783         m = *m0 = pf_join_fragment(frag);
 784         frag = NULL;
 785
 786         if (m->m_flags & M_PKTHDR) {
 787                 int plen = 0;
 788                 for (m = *m0; m; m = m->m_next)
 789                         plen += m->m_len;
 790                 m = *m0;
 791                 m->m_pkthdr.len = plen;
 792         }
 793
 794         ip = mtod(m, struct ip *);
 795         ip->ip_sum = pf_cksum_fixup(ip->ip_sum, ip->ip_len,
 796             htons(hdrlen + total), 0);
 797         ip->ip_len = htons(hdrlen + total);
 798         ip->ip_sum = pf_cksum_fixup(ip->ip_sum, ip->ip_off,
 799             ip->ip_off & ~(IP_MF|IP_OFFMASK), 0);
 800         ip->ip_off &= ~(IP_MF|IP_OFFMASK);
 801
 802         if (hdrlen + total > IP_MAXPACKET) {
 803                 DPFPRINTF(("drop: too big: %d\n", total));
 804                 ip->ip_len = 0;
 805                 REASON_SET(reason, PFRES_SHORT);
 806                 /* PF_DROP requires a valid mbuf *m0 in pf_test() */
 807                 return (PF_DROP);
 808         }
 809
 810         DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len)));
 811         return (PF_PASS);
 812 }
 813 #endif  /* INET */
 814
 815 #ifdef INET6
 816 static int
 817 pf_reassemble6(struct mbuf **m0, struct ip6_hdr *ip6, struct ip6_frag *fraghdr,
 818     uint16_t hdrlen, uint16_t extoff, u_short *reason)
 819 {
 820         struct mbuf             *m = *m0;
 821         struct pf_frent         *frent;
 822         struct pf_fragment      *frag;
 823         struct pf_fragment_cmp   key;
 824         struct m_tag            *mtag;
 825         struct pf_fragment_tag  *ftag;
 826         int                      off;
 827         uint32_t                 frag_id;
 828         uint16_t                 total, maxlen;
 829         uint8_t                  proto;
 830
 831         PF_FRAG_LOCK();
 832
 833         /* Get an entry for the fragment queue. */
 834         if ((frent = pf_create_fragment(reason)) == NULL) {
 835                 PF_FRAG_UNLOCK();
 836                 return (PF_DROP);
 837         }
 838
 839         frent->fe_m = m;
 840         frent->fe_hdrlen = hdrlen;
 841         frent->fe_extoff = extoff;
 842         frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen;
 843         frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK);
 844         frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG;
 845
 846         key.frc_src.v6 = ip6->ip6_src;
 847         key.frc_dst.v6 = ip6->ip6_dst;
 848         key.frc_af = AF_INET6;
 849         /* Only the first fragment's protocol is relevant. */
 850         key.frc_proto = 0;
 851         key.frc_id = fraghdr->ip6f_ident;
 852
 853         if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) {
 854                 PF_FRAG_UNLOCK();
 855                 return (PF_DROP);
 856         }
 857
 858         /* The mbuf is part of the fragment entry, no direct free or access. */
 859         m = *m0 = NULL;
 860
 861         if (frag->fr_holes) {
 862                 DPFPRINTF(("frag %d, holes %d\n", frag->fr_id,
 863                     frag->fr_holes));
 864                 PF_FRAG_UNLOCK();
 865                 return (PF_PASS);  /* Drop because *m0 is NULL, no error. */
 866         }
 867
 868         /* We have all the data. */
 869         frent = TAILQ_FIRST(&frag->fr_queue);
 870         KASSERT(frent != NULL, ("frent != NULL"));
 871         extoff = frent->fe_extoff;
 872         maxlen = frag->fr_maxlen;
 873         frag_id = frag->fr_id;
 874         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 875                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 876         hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag);
 877
 878         m = *m0 = pf_join_fragment(frag);
 879         frag = NULL;
 880
 881         PF_FRAG_UNLOCK();
 882
 883         /* Take protocol from first fragment header. */
 884         m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off);
 885         KASSERT(m, ("%s: short mbuf chain", __func__));
 886         proto = *(mtod(m, uint8_t *) + off);
 887         m = *m0;
 888
 889         /* Delete frag6 header */
 890         if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0)
 891                 goto fail;
 892
 893         if (m->m_flags & M_PKTHDR) {
 894                 int plen = 0;
 895                 for (m = *m0; m; m = m->m_next)
 896                         plen += m->m_len;
 897                 m = *m0;
 898                 m->m_pkthdr.len = plen;
 899         }
 900
 901         if ((mtag = m_tag_get(PACKET_TAG_PF_REASSEMBLED,
 902             sizeof(struct pf_fragment_tag), M_NOWAIT)) == NULL)
 903                 goto fail;
 904         ftag = (struct pf_fragment_tag *)(mtag + 1);
 905         ftag->ft_hdrlen = hdrlen;
 906         ftag->ft_extoff = extoff;
 907         ftag->ft_maxlen = maxlen;
 908         ftag->ft_id = frag_id;
 909         m_tag_prepend(m, mtag);
 910
 911         ip6 = mtod(m, struct ip6_hdr *);
 912         ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total);
 913         if (extoff) {
 914                 /* Write protocol into next field of last extension header. */
 915                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
 916                     &off);
 917                 KASSERT(m, ("%s: short mbuf chain", __func__));
 918                 *(mtod(m, char *) + off) = proto;
 919                 m = *m0;
 920         } else
 921                 ip6->ip6_nxt = proto;
 922
 923         if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) {
 924                 DPFPRINTF(("drop: too big: %d\n", total));
 925                 ip6->ip6_plen = 0;
 926                 REASON_SET(reason, PFRES_SHORT);
 927                 /* PF_DROP requires a valid mbuf *m0 in pf_test6(). */
 928                 return (PF_DROP);
 929         }
 930
 931         DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip6->ip6_plen)));
 932         return (PF_PASS);
 933
 934 fail:
 935         REASON_SET(reason, PFRES_MEMORY);
 936         /* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */
 937         return (PF_DROP);
 938 }
 939 #endif  /* INET6 */
 940
 941 #ifdef INET6
 942 int
 943 pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag,
 944     bool forward)
 945 {
 946         struct mbuf             *m = *m0, *t;
 947         struct ip6_hdr          *hdr;
 948         struct pf_fragment_tag  *ftag = (struct pf_fragment_tag *)(mtag + 1);
 949         struct pf_pdesc          pd;
 950         uint32_t                 frag_id;
 951         uint16_t                 hdrlen, extoff, maxlen;
 952         uint8_t                  proto;
 953         int                      error, action;
 954
 955         hdrlen = ftag->ft_hdrlen;
 956         extoff = ftag->ft_extoff;
 957         maxlen = ftag->ft_maxlen;
 958         frag_id = ftag->ft_id;
 959         m_tag_delete(m, mtag);
 960         mtag = NULL;
 961         ftag = NULL;
 962
 963         if (extoff) {
 964                 int off;
 965
 966                 /* Use protocol from next field of last extension header */
 967                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
 968                     &off);
 969                 KASSERT((m != NULL), ("pf_refragment6: short mbuf chain"));
 970                 proto = *(mtod(m, uint8_t *) + off);
 971                 *(mtod(m, char *) + off) = IPPROTO_FRAGMENT;
 972                 m = *m0;
 973         } else {
 974                 hdr = mtod(m, struct ip6_hdr *);
 975                 proto = hdr->ip6_nxt;
 976                 hdr->ip6_nxt = IPPROTO_FRAGMENT;
 977         }
 978
 979         /* In case of link-local traffic we'll need a scope set. */
 980         hdr = mtod(m, struct ip6_hdr *);
 981
 982         in6_setscope(&hdr->ip6_src, ifp, NULL);
 983         in6_setscope(&hdr->ip6_dst, ifp, NULL);
 984
 985         /* The MTU must be a multiple of 8 bytes, or we risk doing the
 986          * fragmentation wrong. */
 987         maxlen = maxlen & ~7;
 988
 989         /*
 990          * Maxlen may be less than 8 if there was only a single
 991          * fragment.  As it was fragmented before, add a fragment
 992          * header also for a single fragment.  If total or maxlen
 993          * is less than 8, ip6_fragment() will return EMSGSIZE and
 994          * we drop the packet.
 995          */
 996         error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id);
 997         m = (*m0)->m_nextpkt;
 998         (*m0)->m_nextpkt = NULL;
 999         if (error == 0) {
1000                 /* The first mbuf contains the unfragmented packet. */
1001                 m_freem(*m0);
1002                 *m0 = NULL;
1003                 action = PF_PASS;
1004         } else {
1005                 /* Drop expects an mbuf to free. */
1006                 DPFPRINTF(("refragment error %d\n", error));
1007                 action = PF_DROP;
1008         }
1009         for (; m; m = t) {
1010                 t = m->m_nextpkt;
1011                 m->m_nextpkt = NULL;
1012                 m->m_flags |= M_SKIP_FIREWALL;
1013                 memset(&pd, 0, sizeof(pd));
1014                 pd.pf_mtag = pf_find_mtag(m);
1015                 if (error == 0)
1016                         if (forward) {
1017                                 MPASS(m->m_pkthdr.rcvif != NULL);
1018                                 ip6_forward(m, 0);
1019                         } else {
1020                                 (void)ip6_output(m, NULL, NULL, 0, NULL, NULL,
1021                                     NULL);
1022                         }
1023                 else
1024                         m_freem(m);
1025         }
1026
1027         return (action);
1028 }
1029 #endif /* INET6 */
1030
1031 #ifdef INET
1032 int
1033 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kkif *kif, u_short *reason,
1034     struct pf_pdesc *pd)
1035 {
1036         struct mbuf             *m = *m0;
1037         struct pf_krule         *r;
1038         struct ip               *h = mtod(m, struct ip *);
1039         int                      mff = (ntohs(h->ip_off) & IP_MF);
1040         int                      hlen = h->ip_hl << 2;
1041         u_int16_t                fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
1042         u_int16_t                max;
1043         int                      ip_len;
1044         int                      tag = -1;
1045         int                      verdict;
1046         int                      srs;
1047
1048         PF_RULES_RASSERT();
1049
1050         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1051         /* Check if there any scrub rules. Lack of scrub rules means enforced
1052          * packet normalization operation just like in OpenBSD. */
1053         srs = (r != NULL);
1054         while (r != NULL) {
1055                 pf_counter_u64_add(&r->evaluations, 1);
1056                 if (pfi_kkif_match(r->kif, kif) == r->ifnot)
1057                         r = r->skip[PF_SKIP_IFP].ptr;
1058                 else if (r->direction && r->direction != dir)
1059                         r = r->skip[PF_SKIP_DIR].ptr;
1060                 else if (r->af && r->af != AF_INET)
1061                         r = r->skip[PF_SKIP_AF].ptr;
1062                 else if (r->proto && r->proto != h->ip_p)
1063                         r = r->skip[PF_SKIP_PROTO].ptr;
1064                 else if (PF_MISMATCHAW(&r->src.addr,
1065                     (struct pf_addr *)&h->ip_src.s_addr, AF_INET,
1066                     r->src.neg, kif, M_GETFIB(m)))
1067                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1068                 else if (PF_MISMATCHAW(&r->dst.addr,
1069                     (struct pf_addr *)&h->ip_dst.s_addr, AF_INET,
1070                     r->dst.neg, NULL, M_GETFIB(m)))
1071                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1072                 else if (r->match_tag && !pf_match_tag(m, r, &tag,
1073                     pd->pf_mtag ? pd->pf_mtag->tag : 0))
1074                         r = TAILQ_NEXT(r, entries);
1075                 else
1076                         break;
1077         }
1078
1079         if (srs) {
1080                 /* With scrub rules present IPv4 normalization happens only
1081                  * if one of rules has matched and it's not a "no scrub" rule */
1082                 if (r == NULL || r->action == PF_NOSCRUB)
1083                         return (PF_PASS);
1084
1085                 pf_counter_u64_critical_enter();
1086                 pf_counter_u64_add_protected(&r->packets[dir == PF_OUT], 1);
1087                 pf_counter_u64_add_protected(&r->bytes[dir == PF_OUT], pd->tot_len);
1088                 pf_counter_u64_critical_exit();
1089         } else if ((!V_pf_status.reass && (h->ip_off & htons(IP_MF | IP_OFFMASK)))) {
1090                 /* With no scrub rules IPv4 fragment reassembly depends on the
1091                  * global switch. Fragments can be dropped early if reassembly
1092                  * is disabled. */
1093                 REASON_SET(reason, PFRES_NORM);
1094                 goto drop;
1095         }
1096
1097         /* Check for illegal packets */
1098         if (hlen < (int)sizeof(struct ip)) {
1099                 REASON_SET(reason, PFRES_NORM);
1100                 goto drop;
1101         }
1102
1103         if (hlen > ntohs(h->ip_len)) {
1104                 REASON_SET(reason, PFRES_NORM);
1105                 goto drop;
1106         }
1107
1108         /* Clear IP_DF if the rule uses the no-df option or we're in no-df mode */
1109         if ((((r && r->rule_flag & PFRULE_NODF) ||
1110             (V_pf_status.reass & PF_REASS_NODF)) && h->ip_off & htons(IP_DF)
1111         )) {
1112                 u_int16_t ip_off = h->ip_off;
1113
1114                 h->ip_off &= htons(~IP_DF);
1115                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1116         }
1117
1118         /* We will need other tests here */
1119         if (!fragoff && !mff)
1120                 goto no_fragment;
1121
1122         /* We're dealing with a fragment now. Don't allow fragments
1123          * with IP_DF to enter the cache. If the flag was cleared by
1124          * no-df above, fine. Otherwise drop it.
1125          */
1126         if (h->ip_off & htons(IP_DF)) {
1127                 DPFPRINTF(("IP_DF\n"));
1128                 goto bad;
1129         }
1130
1131         ip_len = ntohs(h->ip_len) - hlen;
1132
1133         /* All fragments are 8 byte aligned */
1134         if (mff && (ip_len & 0x7)) {
1135                 DPFPRINTF(("mff and %d\n", ip_len));
1136                 goto bad;
1137         }
1138
1139         /* Respect maximum length */
1140         if (fragoff + ip_len > IP_MAXPACKET) {
1141                 DPFPRINTF(("max packet %d\n", fragoff + ip_len));
1142                 goto bad;
1143         }
1144
1145         if (r==NULL || !(r->rule_flag & PFRULE_FRAGMENT_NOREASS)) {
1146                 max = fragoff + ip_len;
1147
1148                 /* Fully buffer all of the fragments
1149                  * Might return a completely reassembled mbuf, or NULL */
1150                 PF_FRAG_LOCK();
1151                 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
1152                 verdict = pf_reassemble(m0, h, dir, reason);
1153                 PF_FRAG_UNLOCK();
1154
1155                 if (verdict != PF_PASS)
1156                         return (PF_DROP);
1157
1158                 m = *m0;
1159                 if (m == NULL)
1160                         return (PF_DROP);
1161
1162                 h = mtod(m, struct ip *);
1163
1164  no_fragment:
1165                 /* At this point, only IP_DF is allowed in ip_off */
1166                 if (h->ip_off & ~htons(IP_DF)) {
1167                         u_int16_t ip_off = h->ip_off;
1168
1169                         h->ip_off &= htons(IP_DF);
1170                         h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1171                 }
1172         }
1173         if (r != NULL) {
1174                 int scrub_flags = pf_rule_to_scrub_flags(r->rule_flag);
1175                 pf_scrub_ip(&m, scrub_flags, r->min_ttl, r->set_tos);
1176         }
1177
1178         return (PF_PASS);
1179
1180  bad:
1181         DPFPRINTF(("dropping bad fragment\n"));
1182         REASON_SET(reason, PFRES_FRAG);
1183  drop:
1184         if (r != NULL && r->log)
1185                 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
1186                     1);
1187
1188         return (PF_DROP);
1189 }
1190 #endif
1191
1192 #ifdef INET6
1193 int
1194 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kkif *kif,
1195     u_short *reason, struct pf_pdesc *pd)
1196 {
1197         struct mbuf             *m = *m0;
1198         struct pf_krule         *r;
1199         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
1200         int                      extoff;
1201         int                      off;
1202         struct ip6_ext           ext;
1203         struct ip6_opt           opt;
1204         struct ip6_frag          frag;
1205         u_int32_t                plen;
1206         int                      optend;
1207         int                      ooff;
1208         u_int8_t                 proto;
1209         int                      terminal;
1210         int                      srs;
1211
1212         PF_RULES_RASSERT();
1213
1214         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1215         /* Check if there any scrub rules. Lack of scrub rules means enforced
1216          * packet normalization operation just like in OpenBSD. */
1217         srs = (r != NULL);
1218         while (r != NULL) {
1219                 pf_counter_u64_add(&r->evaluations, 1);
1220                 if (pfi_kkif_match(r->kif, kif) == r->ifnot)
1221                         r = r->skip[PF_SKIP_IFP].ptr;
1222                 else if (r->direction && r->direction != dir)
1223                         r = r->skip[PF_SKIP_DIR].ptr;
1224                 else if (r->af && r->af != AF_INET6)
1225                         r = r->skip[PF_SKIP_AF].ptr;
1226 #if 0 /* header chain! */
1227                 else if (r->proto && r->proto != h->ip6_nxt)
1228                         r = r->skip[PF_SKIP_PROTO].ptr;
1229 #endif
1230                 else if (PF_MISMATCHAW(&r->src.addr,
1231                     (struct pf_addr *)&h->ip6_src, AF_INET6,
1232                     r->src.neg, kif, M_GETFIB(m)))
1233                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1234                 else if (PF_MISMATCHAW(&r->dst.addr,
1235                     (struct pf_addr *)&h->ip6_dst, AF_INET6,
1236                     r->dst.neg, NULL, M_GETFIB(m)))
1237                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1238                 else
1239                         break;
1240         }
1241
1242         if (srs) {
1243                 /* With scrub rules present IPv6 normalization happens only
1244                  * if one of rules has matched and it's not a "no scrub" rule */
1245                 if (r == NULL || r->action == PF_NOSCRUB)
1246                         return (PF_PASS);
1247
1248                 pf_counter_u64_critical_enter();
1249                 pf_counter_u64_add_protected(&r->packets[dir == PF_OUT], 1);
1250                 pf_counter_u64_add_protected(&r->bytes[dir == PF_OUT], pd->tot_len);
1251                 pf_counter_u64_critical_exit();
1252         }
1253
1254         /* Check for illegal packets */
1255         if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len)
1256                 goto drop;
1257
1258         plen = ntohs(h->ip6_plen);
1259         /* jumbo payload option not supported */
1260         if (plen == 0)
1261                 goto drop;
1262
1263         extoff = 0;
1264         off = sizeof(struct ip6_hdr);
1265         proto = h->ip6_nxt;
1266         terminal = 0;
1267         do {
1268                 switch (proto) {
1269                 case IPPROTO_FRAGMENT:
1270                         goto fragment;
1271                         break;
1272                 case IPPROTO_AH:
1273                 case IPPROTO_ROUTING:
1274                 case IPPROTO_DSTOPTS:
1275                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1276                             NULL, AF_INET6))
1277                                 goto shortpkt;
1278                         extoff = off;
1279                         if (proto == IPPROTO_AH)
1280                                 off += (ext.ip6e_len + 2) * 4;
1281                         else
1282                                 off += (ext.ip6e_len + 1) * 8;
1283                         proto = ext.ip6e_nxt;
1284                         break;
1285                 case IPPROTO_HOPOPTS:
1286                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1287                             NULL, AF_INET6))
1288                                 goto shortpkt;
1289                         extoff = off;
1290                         optend = off + (ext.ip6e_len + 1) * 8;
1291                         ooff = off + sizeof(ext);
1292                         do {
1293                                 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type,
1294                                     sizeof(opt.ip6o_type), NULL, NULL,
1295                                     AF_INET6))
1296                                         goto shortpkt;
1297                                 if (opt.ip6o_type == IP6OPT_PAD1) {
1298                                         ooff++;
1299                                         continue;
1300                                 }
1301                                 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt),
1302                                     NULL, NULL, AF_INET6))
1303                                         goto shortpkt;
1304                                 if (ooff + sizeof(opt) + opt.ip6o_len > optend)
1305                                         goto drop;
1306                                 if (opt.ip6o_type == IP6OPT_JUMBO)
1307                                         goto drop;
1308                                 ooff += sizeof(opt) + opt.ip6o_len;
1309                         } while (ooff < optend);
1310
1311                         off = optend;
1312                         proto = ext.ip6e_nxt;
1313                         break;
1314                 default:
1315                         terminal = 1;
1316                         break;
1317                 }
1318         } while (!terminal);
1319
1320         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1321                 goto shortpkt;
1322
1323         if (r != NULL) {
1324                 int scrub_flags = pf_rule_to_scrub_flags(r->rule_flag);
1325                 pf_scrub_ip6(&m, scrub_flags, r->min_ttl, r->set_tos);
1326         }
1327
1328         return (PF_PASS);
1329
1330  fragment:
1331         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1332                 goto shortpkt;
1333
1334         if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6))
1335                 goto shortpkt;
1336
1337         /* Offset now points to data portion. */
1338         off += sizeof(frag);
1339
1340         /* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */
1341         if (pf_reassemble6(m0, h, &frag, off, extoff, reason) != PF_PASS)
1342                 return (PF_DROP);
1343         m = *m0;
1344         if (m == NULL)
1345                 return (PF_DROP);
1346
1347         pd->flags |= PFDESC_IP_REAS;
1348         return (PF_PASS);
1349
1350  shortpkt:
1351         REASON_SET(reason, PFRES_SHORT);
1352         if (r != NULL && r->log)
1353                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1354                     1);
1355         return (PF_DROP);
1356
1357  drop:
1358         REASON_SET(reason, PFRES_NORM);
1359         if (r != NULL && r->log)
1360                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1361                     1);
1362         return (PF_DROP);
1363 }
1364 #endif /* INET6 */
1365
1366 int
1367 pf_normalize_tcp(int dir, struct pfi_kkif *kif, struct mbuf *m, int ipoff,
1368     int off, void *h, struct pf_pdesc *pd)
1369 {
1370         struct pf_krule *r, *rm = NULL;
1371         struct tcphdr   *th = &pd->hdr.tcp;
1372         int              rewrite = 0;
1373         u_short          reason;
1374         u_int8_t         flags;
1375         sa_family_t      af = pd->af;
1376         int              srs;
1377
1378         PF_RULES_RASSERT();
1379
1380         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1381         /* Check if there any scrub rules. Lack of scrub rules means enforced
1382          * packet normalization operation just like in OpenBSD. */
1383         srs = (r != NULL);
1384         while (r != NULL) {
1385                 pf_counter_u64_add(&r->evaluations, 1);
1386                 if (pfi_kkif_match(r->kif, kif) == r->ifnot)
1387                         r = r->skip[PF_SKIP_IFP].ptr;
1388                 else if (r->direction && r->direction != dir)
1389                         r = r->skip[PF_SKIP_DIR].ptr;
1390                 else if (r->af && r->af != af)
1391                         r = r->skip[PF_SKIP_AF].ptr;
1392                 else if (r->proto && r->proto != pd->proto)
1393                         r = r->skip[PF_SKIP_PROTO].ptr;
1394                 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af,
1395                     r->src.neg, kif, M_GETFIB(m)))
1396                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1397                 else if (r->src.port_op && !pf_match_port(r->src.port_op,
1398                             r->src.port[0], r->src.port[1], th->th_sport))
1399                         r = r->skip[PF_SKIP_SRC_PORT].ptr;
1400                 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af,
1401                     r->dst.neg, NULL, M_GETFIB(m)))
1402                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1403                 else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
1404                             r->dst.port[0], r->dst.port[1], th->th_dport))
1405                         r = r->skip[PF_SKIP_DST_PORT].ptr;
1406                 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match(
1407                             pf_osfp_fingerprint(pd, m, off, th),
1408                             r->os_fingerprint))
1409                         r = TAILQ_NEXT(r, entries);
1410                 else {
1411                         rm = r;
1412                         break;
1413                 }
1414         }
1415
1416         if (srs) {
1417                 /* With scrub rules present TCP normalization happens only
1418                  * if one of rules has matched and it's not a "no scrub" rule */
1419                 if (rm == NULL || rm->action == PF_NOSCRUB)
1420                         return (PF_PASS);
1421
1422                 pf_counter_u64_critical_enter();
1423                 pf_counter_u64_add_protected(&r->packets[dir == PF_OUT], 1);
1424                 pf_counter_u64_add_protected(&r->bytes[dir == PF_OUT], pd->tot_len);
1425                 pf_counter_u64_critical_exit();
1426         }
1427
1428         if (rm && rm->rule_flag & PFRULE_REASSEMBLE_TCP)
1429                 pd->flags |= PFDESC_TCP_NORM;
1430
1431         flags = th->th_flags;
1432         if (flags & TH_SYN) {
1433                 /* Illegal packet */
1434                 if (flags & TH_RST)
1435                         goto tcp_drop;
1436
1437                 if (flags & TH_FIN)
1438                         goto tcp_drop;
1439         } else {
1440                 /* Illegal packet */
1441                 if (!(flags & (TH_ACK|TH_RST)))
1442                         goto tcp_drop;
1443         }
1444
1445         if (!(flags & TH_ACK)) {
1446                 /* These flags are only valid if ACK is set */
1447                 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG))
1448                         goto tcp_drop;
1449         }
1450
1451         /* Check for illegal header length */
1452         if (th->th_off < (sizeof(struct tcphdr) >> 2))
1453                 goto tcp_drop;
1454
1455         /* If flags changed, or reserved data set, then adjust */
1456         if (flags != th->th_flags || th->th_x2 != 0) {
1457                 u_int16_t       ov, nv;
1458
1459                 ov = *(u_int16_t *)(&th->th_ack + 1);
1460                 th->th_flags = flags;
1461                 th->th_x2 = 0;
1462                 nv = *(u_int16_t *)(&th->th_ack + 1);
1463
1464                 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, ov, nv, 0);
1465                 rewrite = 1;
1466         }
1467
1468         /* Remove urgent pointer, if TH_URG is not set */
1469         if (!(flags & TH_URG) && th->th_urp) {
1470                 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, th->th_urp,
1471                     0, 0);
1472                 th->th_urp = 0;
1473                 rewrite = 1;
1474         }
1475
1476         /* Set MSS for old-style scrub rules.
1477          * The function performs its own copyback. */
1478         if (rm != NULL && rm->max_mss)
1479                 pf_normalize_mss(m, off, pd, rm->max_mss);
1480
1481         /* copy back packet headers if we sanitized */
1482         if (rewrite)
1483                 m_copyback(m, off, sizeof(*th), (caddr_t)th);
1484
1485         return (PF_PASS);
1486
1487  tcp_drop:
1488         REASON_SET(&reason, PFRES_NORM);
1489         if (rm != NULL && r->log)
1490                 PFLOG_PACKET(kif, m, AF_INET, dir, reason, r, NULL, NULL, pd,
1491                     1);
1492         return (PF_DROP);
1493 }
1494
1495 int
1496 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd,
1497     struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst)
1498 {
1499         u_int32_t tsval, tsecr;
1500         u_int8_t hdr[60];
1501         u_int8_t *opt;
1502
1503         KASSERT((src->scrub == NULL),
1504             ("pf_normalize_tcp_init: src->scrub != NULL"));
1505
1506         src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT);
1507         if (src->scrub == NULL)
1508                 return (1);
1509
1510         switch (pd->af) {
1511 #ifdef INET
1512         case AF_INET: {
1513                 struct ip *h = mtod(m, struct ip *);
1514                 src->scrub->pfss_ttl = h->ip_ttl;
1515                 break;
1516         }
1517 #endif /* INET */
1518 #ifdef INET6
1519         case AF_INET6: {
1520                 struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1521                 src->scrub->pfss_ttl = h->ip6_hlim;
1522                 break;
1523         }
1524 #endif /* INET6 */
1525         }
1526
1527         /*
1528          * All normalizations below are only begun if we see the start of
1529          * the connections.  They must all set an enabled bit in pfss_flags
1530          */
1531         if ((th->th_flags & TH_SYN) == 0)
1532                 return (0);
1533
1534         if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub &&
1535             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1536                 /* Diddle with TCP options */
1537                 int hlen;
1538                 opt = hdr + sizeof(struct tcphdr);
1539                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1540                 while (hlen >= TCPOLEN_TIMESTAMP) {
1541                         switch (*opt) {
1542                         case TCPOPT_EOL:        /* FALLTHROUGH */
1543                         case TCPOPT_NOP:
1544                                 opt++;
1545                                 hlen--;
1546                                 break;
1547                         case TCPOPT_TIMESTAMP:
1548                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1549                                         src->scrub->pfss_flags |=
1550                                             PFSS_TIMESTAMP;
1551                                         src->scrub->pfss_ts_mod =
1552                                             htonl(arc4random());
1553
1554                                         /* note PFSS_PAWS not set yet */
1555                                         memcpy(&tsval, &opt[2],
1556                                             sizeof(u_int32_t));
1557                                         memcpy(&tsecr, &opt[6],
1558                                             sizeof(u_int32_t));
1559                                         src->scrub->pfss_tsval0 = ntohl(tsval);
1560                                         src->scrub->pfss_tsval = ntohl(tsval);
1561                                         src->scrub->pfss_tsecr = ntohl(tsecr);
1562                                         getmicrouptime(&src->scrub->pfss_last);
1563                                 }
1564                                 /* FALLTHROUGH */
1565                         default:
1566                                 hlen -= MAX(opt[1], 2);
1567                                 opt += MAX(opt[1], 2);
1568                                 break;
1569                         }
1570                 }
1571         }
1572
1573         return (0);
1574 }
1575
1576 void
1577 pf_normalize_tcp_cleanup(struct pf_kstate *state)
1578 {
1579         uma_zfree(V_pf_state_scrub_z, state->src.scrub);
1580         uma_zfree(V_pf_state_scrub_z, state->dst.scrub);
1581
1582         /* Someday... flush the TCP segment reassembly descriptors. */
1583 }
1584
1585 int
1586 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd,
1587     u_short *reason, struct tcphdr *th, struct pf_kstate *state,
1588     struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback)
1589 {
1590         struct timeval uptime;
1591         u_int32_t tsval, tsecr;
1592         u_int tsval_from_last;
1593         u_int8_t hdr[60];
1594         u_int8_t *opt;
1595         int copyback = 0;
1596         int got_ts = 0;
1597         size_t startoff;
1598
1599         KASSERT((src->scrub || dst->scrub),
1600             ("%s: src->scrub && dst->scrub!", __func__));
1601
1602         /*
1603          * Enforce the minimum TTL seen for this connection.  Negate a common
1604          * technique to evade an intrusion detection system and confuse
1605          * firewall state code.
1606          */
1607         switch (pd->af) {
1608 #ifdef INET
1609         case AF_INET: {
1610                 if (src->scrub) {
1611                         struct ip *h = mtod(m, struct ip *);
1612                         if (h->ip_ttl > src->scrub->pfss_ttl)
1613                                 src->scrub->pfss_ttl = h->ip_ttl;
1614                         h->ip_ttl = src->scrub->pfss_ttl;
1615                 }
1616                 break;
1617         }
1618 #endif /* INET */
1619 #ifdef INET6
1620         case AF_INET6: {
1621                 if (src->scrub) {
1622                         struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1623                         if (h->ip6_hlim > src->scrub->pfss_ttl)
1624                                 src->scrub->pfss_ttl = h->ip6_hlim;
1625                         h->ip6_hlim = src->scrub->pfss_ttl;
1626                 }
1627                 break;
1628         }
1629 #endif /* INET6 */
1630         }
1631
1632         if (th->th_off > (sizeof(struct tcphdr) >> 2) &&
1633             ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) ||
1634             (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) &&
1635             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1636                 /* Diddle with TCP options */
1637                 int hlen;
1638                 opt = hdr + sizeof(struct tcphdr);
1639                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1640                 while (hlen >= TCPOLEN_TIMESTAMP) {
1641                         startoff = opt - (hdr + sizeof(struct tcphdr));
1642                         switch (*opt) {
1643                         case TCPOPT_EOL:        /* FALLTHROUGH */
1644                         case TCPOPT_NOP:
1645                                 opt++;
1646                                 hlen--;
1647                                 break;
1648                         case TCPOPT_TIMESTAMP:
1649                                 /* Modulate the timestamps.  Can be used for
1650                                  * NAT detection, OS uptime determination or
1651                                  * reboot detection.
1652                                  */
1653
1654                                 if (got_ts) {
1655                                         /* Huh?  Multiple timestamps!? */
1656                                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1657                                                 DPFPRINTF(("multiple TS??\n"));
1658                                                 pf_print_state(state);
1659                                                 printf("\n");
1660                                         }
1661                                         REASON_SET(reason, PFRES_TS);
1662                                         return (PF_DROP);
1663                                 }
1664                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1665                                         memcpy(&tsval, &opt[2],
1666                                             sizeof(u_int32_t));
1667                                         if (tsval && src->scrub &&
1668                                             (src->scrub->pfss_flags &
1669                                             PFSS_TIMESTAMP)) {
1670                                                 tsval = ntohl(tsval);
1671                                                 pf_patch_32_unaligned(m,
1672                                                     &th->th_sum,
1673                                                     &opt[2],
1674                                                     htonl(tsval +
1675                                                     src->scrub->pfss_ts_mod),
1676                                                     PF_ALGNMNT(startoff),
1677                                                     0);
1678                                                 copyback = 1;
1679                                         }
1680
1681                                         /* Modulate TS reply iff valid (!0) */
1682                                         memcpy(&tsecr, &opt[6],
1683                                             sizeof(u_int32_t));
1684                                         if (tsecr && dst->scrub &&
1685                                             (dst->scrub->pfss_flags &
1686                                             PFSS_TIMESTAMP)) {
1687                                                 tsecr = ntohl(tsecr)
1688                                                     - dst->scrub->pfss_ts_mod;
1689                                                 pf_patch_32_unaligned(m,
1690                                                     &th->th_sum,
1691                                                     &opt[6],
1692                                                     htonl(tsecr),
1693                                                     PF_ALGNMNT(startoff),
1694                                                     0);
1695                                                 copyback = 1;
1696                                         }
1697                                         got_ts = 1;
1698                                 }
1699                                 /* FALLTHROUGH */
1700                         default:
1701                                 hlen -= MAX(opt[1], 2);
1702                                 opt += MAX(opt[1], 2);
1703                                 break;
1704                         }
1705                 }
1706                 if (copyback) {
1707                         /* Copyback the options, caller copys back header */
1708                         *writeback = 1;
1709                         m_copyback(m, off + sizeof(struct tcphdr),
1710                             (th->th_off << 2) - sizeof(struct tcphdr), hdr +
1711                             sizeof(struct tcphdr));
1712                 }
1713         }
1714
1715         /*
1716          * Must invalidate PAWS checks on connections idle for too long.
1717          * The fastest allowed timestamp clock is 1ms.  That turns out to
1718          * be about 24 days before it wraps.  XXX Right now our lowerbound
1719          * TS echo check only works for the first 12 days of a connection
1720          * when the TS has exhausted half its 32bit space
1721          */
1722 #define TS_MAX_IDLE     (24*24*60*60)
1723 #define TS_MAX_CONN     (12*24*60*60)   /* XXX remove when better tsecr check */
1724
1725         getmicrouptime(&uptime);
1726         if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) &&
1727             (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE ||
1728             time_uptime - state->creation > TS_MAX_CONN))  {
1729                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1730                         DPFPRINTF(("src idled out of PAWS\n"));
1731                         pf_print_state(state);
1732                         printf("\n");
1733                 }
1734                 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS)
1735                     | PFSS_PAWS_IDLED;
1736         }
1737         if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) &&
1738             uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) {
1739                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1740                         DPFPRINTF(("dst idled out of PAWS\n"));
1741                         pf_print_state(state);
1742                         printf("\n");
1743                 }
1744                 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS)
1745                     | PFSS_PAWS_IDLED;
1746         }
1747
1748         if (got_ts && src->scrub && dst->scrub &&
1749             (src->scrub->pfss_flags & PFSS_PAWS) &&
1750             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1751                 /* Validate that the timestamps are "in-window".
1752                  * RFC1323 describes TCP Timestamp options that allow
1753                  * measurement of RTT (round trip time) and PAWS
1754                  * (protection against wrapped sequence numbers).  PAWS
1755                  * gives us a set of rules for rejecting packets on
1756                  * long fat pipes (packets that were somehow delayed
1757                  * in transit longer than the time it took to send the
1758                  * full TCP sequence space of 4Gb).  We can use these
1759                  * rules and infer a few others that will let us treat
1760                  * the 32bit timestamp and the 32bit echoed timestamp
1761                  * as sequence numbers to prevent a blind attacker from
1762                  * inserting packets into a connection.
1763                  *
1764                  * RFC1323 tells us:
1765                  *  - The timestamp on this packet must be greater than
1766                  *    or equal to the last value echoed by the other
1767                  *    endpoint.  The RFC says those will be discarded
1768                  *    since it is a dup that has already been acked.
1769                  *    This gives us a lowerbound on the timestamp.
1770                  *        timestamp >= other last echoed timestamp
1771                  *  - The timestamp will be less than or equal to
1772                  *    the last timestamp plus the time between the
1773                  *    last packet and now.  The RFC defines the max
1774                  *    clock rate as 1ms.  We will allow clocks to be
1775                  *    up to 10% fast and will allow a total difference
1776                  *    or 30 seconds due to a route change.  And this
1777                  *    gives us an upperbound on the timestamp.
1778                  *        timestamp <= last timestamp + max ticks
1779                  *    We have to be careful here.  Windows will send an
1780                  *    initial timestamp of zero and then initialize it
1781                  *    to a random value after the 3whs; presumably to
1782                  *    avoid a DoS by having to call an expensive RNG
1783                  *    during a SYN flood.  Proof MS has at least one
1784                  *    good security geek.
1785                  *
1786                  *  - The TCP timestamp option must also echo the other
1787                  *    endpoints timestamp.  The timestamp echoed is the
1788                  *    one carried on the earliest unacknowledged segment
1789                  *    on the left edge of the sequence window.  The RFC
1790                  *    states that the host will reject any echoed
1791                  *    timestamps that were larger than any ever sent.
1792                  *    This gives us an upperbound on the TS echo.
1793                  *        tescr <= largest_tsval
1794                  *  - The lowerbound on the TS echo is a little more
1795                  *    tricky to determine.  The other endpoint's echoed
1796                  *    values will not decrease.  But there may be
1797                  *    network conditions that re-order packets and
1798                  *    cause our view of them to decrease.  For now the
1799                  *    only lowerbound we can safely determine is that
1800                  *    the TS echo will never be less than the original
1801                  *    TS.  XXX There is probably a better lowerbound.
1802                  *    Remove TS_MAX_CONN with better lowerbound check.
1803                  *        tescr >= other original TS
1804                  *
1805                  * It is also important to note that the fastest
1806                  * timestamp clock of 1ms will wrap its 32bit space in
1807                  * 24 days.  So we just disable TS checking after 24
1808                  * days of idle time.  We actually must use a 12d
1809                  * connection limit until we can come up with a better
1810                  * lowerbound to the TS echo check.
1811                  */
1812                 struct timeval delta_ts;
1813                 int ts_fudge;
1814
1815                 /*
1816                  * PFTM_TS_DIFF is how many seconds of leeway to allow
1817                  * a host's timestamp.  This can happen if the previous
1818                  * packet got delayed in transit for much longer than
1819                  * this packet.
1820                  */
1821                 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0)
1822                         ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF];
1823
1824                 /* Calculate max ticks since the last timestamp */
1825 #define TS_MAXFREQ      1100            /* RFC max TS freq of 1Khz + 10% skew */
1826 #define TS_MICROSECS    1000000         /* microseconds per second */
1827                 delta_ts = uptime;
1828                 timevalsub(&delta_ts, &src->scrub->pfss_last);
1829                 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ;
1830                 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ);
1831
1832                 if ((src->state >= TCPS_ESTABLISHED &&
1833                     dst->state >= TCPS_ESTABLISHED) &&
1834                     (SEQ_LT(tsval, dst->scrub->pfss_tsecr) ||
1835                     SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) ||
1836                     (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) ||
1837                     SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) {
1838                         /* Bad RFC1323 implementation or an insertion attack.
1839                          *
1840                          * - Solaris 2.6 and 2.7 are known to send another ACK
1841                          *   after the FIN,FIN|ACK,ACK closing that carries
1842                          *   an old timestamp.
1843                          */
1844
1845                         DPFPRINTF(("Timestamp failed %c%c%c%c\n",
1846                             SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ',
1847                             SEQ_GT(tsval, src->scrub->pfss_tsval +
1848                             tsval_from_last) ? '1' : ' ',
1849                             SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ',
1850                             SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' '));
1851                         DPFPRINTF((" tsval: %u  tsecr: %u  +ticks: %u  "
1852                             "idle: %jus %lums\n",
1853                             tsval, tsecr, tsval_from_last,
1854                             (uintmax_t)delta_ts.tv_sec,
1855                             delta_ts.tv_usec / 1000));
1856                         DPFPRINTF((" src->tsval: %u  tsecr: %u\n",
1857                             src->scrub->pfss_tsval, src->scrub->pfss_tsecr));
1858                         DPFPRINTF((" dst->tsval: %u  tsecr: %u  tsval0: %u"
1859                             "\n", dst->scrub->pfss_tsval,
1860                             dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0));
1861                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1862                                 pf_print_state(state);
1863                                 pf_print_flags(th->th_flags);
1864                                 printf("\n");
1865                         }
1866                         REASON_SET(reason, PFRES_TS);
1867                         return (PF_DROP);
1868                 }
1869
1870                 /* XXX I'd really like to require tsecr but it's optional */
1871
1872         } else if (!got_ts && (th->th_flags & TH_RST) == 0 &&
1873             ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED)
1874             || pd->p_len > 0 || (th->th_flags & TH_SYN)) &&
1875             src->scrub && dst->scrub &&
1876             (src->scrub->pfss_flags & PFSS_PAWS) &&
1877             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1878                 /* Didn't send a timestamp.  Timestamps aren't really useful
1879                  * when:
1880                  *  - connection opening or closing (often not even sent).
1881                  *    but we must not let an attacker to put a FIN on a
1882                  *    data packet to sneak it through our ESTABLISHED check.
1883                  *  - on a TCP reset.  RFC suggests not even looking at TS.
1884                  *  - on an empty ACK.  The TS will not be echoed so it will
1885                  *    probably not help keep the RTT calculation in sync and
1886                  *    there isn't as much danger when the sequence numbers
1887                  *    got wrapped.  So some stacks don't include TS on empty
1888                  *    ACKs :-(
1889                  *
1890                  * To minimize the disruption to mostly RFC1323 conformant
1891                  * stacks, we will only require timestamps on data packets.
1892                  *
1893                  * And what do ya know, we cannot require timestamps on data
1894                  * packets.  There appear to be devices that do legitimate
1895                  * TCP connection hijacking.  There are HTTP devices that allow
1896                  * a 3whs (with timestamps) and then buffer the HTTP request.
1897                  * If the intermediate device has the HTTP response cache, it
1898                  * will spoof the response but not bother timestamping its
1899                  * packets.  So we can look for the presence of a timestamp in
1900                  * the first data packet and if there, require it in all future
1901                  * packets.
1902                  */
1903
1904                 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) {
1905                         /*
1906                          * Hey!  Someone tried to sneak a packet in.  Or the
1907                          * stack changed its RFC1323 behavior?!?!
1908                          */
1909                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1910                                 DPFPRINTF(("Did not receive expected RFC1323 "
1911                                     "timestamp\n"));
1912                                 pf_print_state(state);
1913                                 pf_print_flags(th->th_flags);
1914                                 printf("\n");
1915                         }
1916                         REASON_SET(reason, PFRES_TS);
1917                         return (PF_DROP);
1918                 }
1919         }
1920
1921         /*
1922          * We will note if a host sends his data packets with or without
1923          * timestamps.  And require all data packets to contain a timestamp
1924          * if the first does.  PAWS implicitly requires that all data packets be
1925          * timestamped.  But I think there are middle-man devices that hijack
1926          * TCP streams immediately after the 3whs and don't timestamp their
1927          * packets (seen in a WWW accelerator or cache).
1928          */
1929         if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags &
1930             (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) {
1931                 if (got_ts)
1932                         src->scrub->pfss_flags |= PFSS_DATA_TS;
1933                 else {
1934                         src->scrub->pfss_flags |= PFSS_DATA_NOTS;
1935                         if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub &&
1936                             (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) {
1937                                 /* Don't warn if other host rejected RFC1323 */
1938                                 DPFPRINTF(("Broken RFC1323 stack did not "
1939                                     "timestamp data packet. Disabled PAWS "
1940                                     "security.\n"));
1941                                 pf_print_state(state);
1942                                 pf_print_flags(th->th_flags);
1943                                 printf("\n");
1944                         }
1945                 }
1946         }
1947
1948         /*
1949          * Update PAWS values
1950          */
1951         if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags &
1952             (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) {
1953                 getmicrouptime(&src->scrub->pfss_last);
1954                 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) ||
1955                     (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1956                         src->scrub->pfss_tsval = tsval;
1957
1958                 if (tsecr) {
1959                         if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) ||
1960                             (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1961                                 src->scrub->pfss_tsecr = tsecr;
1962
1963                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 &&
1964                             (SEQ_LT(tsval, src->scrub->pfss_tsval0) ||
1965                             src->scrub->pfss_tsval0 == 0)) {
1966                                 /* tsval0 MUST be the lowest timestamp */
1967                                 src->scrub->pfss_tsval0 = tsval;
1968                         }
1969
1970                         /* Only fully initialized after a TS gets echoed */
1971                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0)
1972                                 src->scrub->pfss_flags |= PFSS_PAWS;
1973                 }
1974         }
1975
1976         /* I have a dream....  TCP segment reassembly.... */
1977         return (0);
1978 }
1979
1980 int
1981 pf_normalize_mss(struct mbuf *m, int off, struct pf_pdesc *pd, u_int16_t maxmss)
1982 {
1983         struct tcphdr   *th = &pd->hdr.tcp;
1984         u_int16_t       *mss;
1985         int              thoff;
1986         int              opt, cnt, optlen = 0;
1987         u_char           opts[TCP_MAXOLEN];
1988         u_char          *optp = opts;
1989         size_t           startoff;
1990
1991         thoff = th->th_off << 2;
1992         cnt = thoff - sizeof(struct tcphdr);
1993
1994         if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt,
1995             NULL, NULL, pd->af))
1996                 return (0);
1997
1998         for (; cnt > 0; cnt -= optlen, optp += optlen) {
1999                 startoff = optp - opts;
2000                 opt = optp[0];
2001                 if (opt == TCPOPT_EOL)
2002                         break;
2003                 if (opt == TCPOPT_NOP)
2004                         optlen = 1;
2005                 else {
2006                         if (cnt < 2)
2007                                 break;
2008                         optlen = optp[1];
2009                         if (optlen < 2 || optlen > cnt)
2010                                 break;
2011                 }
2012                 switch (opt) {
2013                 case TCPOPT_MAXSEG:
2014                         mss = (u_int16_t *)(optp + 2);
2015                         if ((ntohs(*mss)) > maxmss) {
2016                                 pf_patch_16_unaligned(m,
2017                                     &th->th_sum,
2018                                     mss, htons(maxmss),
2019                                     PF_ALGNMNT(startoff),
2020                                     0);
2021                                 m_copyback(m, off + sizeof(*th),
2022                                     thoff - sizeof(*th), opts);
2023                                 m_copyback(m, off, sizeof(*th), (caddr_t)th);
2024                         }
2025                         break;
2026                 default:
2027                         break;
2028                 }
2029         }
2030
2031         return (0);
2032 }
2033
2034 u_int16_t
2035 pf_rule_to_scrub_flags(u_int32_t rule_flags)
2036 {
2037         /*
2038          * Translate pf_krule->rule_flag to pf_krule->scrub_flags.
2039          * The pf_scrub_ip functions have been adapted to the new style of pass
2040          * rules but they might get called if old scrub rules are used.
2041          */
2042         int scrub_flags = 0;
2043
2044         if (rule_flags & PFRULE_SET_TOS) {
2045                 scrub_flags |= PFSTATE_SETTOS;
2046         }
2047         if (rule_flags & PFRULE_RANDOMID)
2048                 scrub_flags |= PFSTATE_RANDOMID;
2049
2050         return scrub_flags;
2051 }
2052
2053 #ifdef INET
2054 void
2055 pf_scrub_ip(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos)
2056 {
2057         struct mbuf             *m = *m0;
2058         struct ip               *h = mtod(m, struct ip *);
2059
2060         /* Clear IP_DF if no-df was requested */
2061         if (flags & PFSTATE_NODF && h->ip_off & htons(IP_DF)) {
2062                 u_int16_t ip_off = h->ip_off;
2063
2064                 h->ip_off &= htons(~IP_DF);
2065                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
2066         }
2067
2068         /* Enforce a minimum ttl, may cause endless packet loops */
2069         if (min_ttl && h->ip_ttl < min_ttl) {
2070                 u_int16_t ip_ttl = h->ip_ttl;
2071
2072                 h->ip_ttl = min_ttl;
2073                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
2074         }
2075
2076         /* Enforce tos */
2077         if (flags & PFSTATE_SETTOS) {
2078                 u_int16_t       ov, nv;
2079
2080                 ov = *(u_int16_t *)h;
2081                 h->ip_tos = tos | (h->ip_tos & IPTOS_ECN_MASK);
2082                 nv = *(u_int16_t *)h;
2083
2084                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0);
2085         }
2086
2087         /* random-id, but not for fragments */
2088         if (flags & PFSTATE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) {
2089                 uint16_t ip_id = h->ip_id;
2090
2091                 ip_fillid(h);
2092                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0);
2093         }
2094 }
2095 #endif /* INET */
2096
2097 #ifdef INET6
2098 void
2099 pf_scrub_ip6(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos)
2100 {
2101         struct mbuf             *m = *m0;
2102         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
2103
2104         /* Enforce a minimum ttl, may cause endless packet loops */
2105         if (min_ttl && h->ip6_hlim < min_ttl)
2106                 h->ip6_hlim = min_ttl;
2107
2108         /* Enforce tos. Set traffic class bits */
2109         if (flags & PFSTATE_SETTOS) {
2110                 h->ip6_flow &= IPV6_FLOWLABEL_MASK | IPV6_VERSION_MASK;
2111                 h->ip6_flow |= htonl((tos | IPV6_ECN(h)) << 20);
2112         }
2113 }
2114 #endif