sys/netpfil/pf/pf_norm.c

   1 /*-
   2  * Copyright 2001 Niels Provos <provos@citi.umich.edu>
   3  * Copyright 2011 Alexander Bluhm <bluhm@openbsd.org>
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  *
  26  *      $OpenBSD: pf_norm.c,v 1.114 2009/01/29 14:11:45 henning Exp $
  27  */
  28
  29 #include <sys/cdefs.h>
  30 __FBSDID("$FreeBSD$");
  31
  32 #include "opt_inet.h"
  33 #include "opt_inet6.h"
  34 #include "opt_pf.h"
  35
  36 #include <sys/param.h>
  37 #include <sys/lock.h>
  38 #include <sys/mbuf.h>
  39 #include <sys/mutex.h>
  40 #include <sys/refcount.h>
  41 #include <sys/rwlock.h>
  42 #include <sys/socket.h>
  43
  44 #include <net/if.h>
  45 #include <net/vnet.h>
  46 #include <net/pfvar.h>
  47 #include <net/if_pflog.h>
  48
  49 #include <netinet/in.h>
  50 #include <netinet/ip.h>
  51 #include <netinet/ip_var.h>
  52 #include <netinet6/ip6_var.h>
  53 #include <netinet/tcp.h>
  54 #include <netinet/tcp_fsm.h>
  55 #include <netinet/tcp_seq.h>
  56
  57 #ifdef INET6
  58 #include <netinet/ip6.h>
  59 #endif /* INET6 */
  60
  61 struct pf_frent {
  62         TAILQ_ENTRY(pf_frent)   fr_next;
  63         struct mbuf     *fe_m;
  64         uint16_t        fe_hdrlen;      /* ipv4 header lenght with ip options
  65                                            ipv6, extension, fragment header */
  66         uint16_t        fe_extoff;      /* last extension header offset or 0 */
  67         uint16_t        fe_len;         /* fragment length */
  68         uint16_t        fe_off;         /* fragment offset */
  69         uint16_t        fe_mff;         /* more fragment flag */
  70 };
  71
  72 struct pf_fragment_cmp {
  73         struct pf_addr  frc_src;
  74         struct pf_addr  frc_dst;
  75         uint32_t        frc_id;
  76         sa_family_t     frc_af;
  77         uint8_t         frc_proto;
  78         uint8_t         frc_direction;
  79 };
  80
  81 struct pf_fragment {
  82         struct pf_fragment_cmp  fr_key;
  83 #define fr_src  fr_key.frc_src
  84 #define fr_dst  fr_key.frc_dst
  85 #define fr_id   fr_key.frc_id
  86 #define fr_af   fr_key.frc_af
  87 #define fr_proto        fr_key.frc_proto
  88 #define fr_direction    fr_key.frc_direction
  89
  90         RB_ENTRY(pf_fragment) fr_entry;
  91         TAILQ_ENTRY(pf_fragment) frag_next;
  92         uint8_t         fr_flags;       /* status flags */
  93 #define PFFRAG_SEENLAST         0x0001  /* Seen the last fragment for this */
  94 #define PFFRAG_NOBUFFER         0x0002  /* Non-buffering fragment cache */
  95 #define PFFRAG_DROP             0x0004  /* Drop all fragments */
  96 #define BUFFER_FRAGMENTS(fr)    (!((fr)->fr_flags & PFFRAG_NOBUFFER))
  97         uint16_t        fr_max;         /* fragment data max */
  98         uint32_t        fr_timeout;
  99         uint16_t        fr_maxlen;      /* maximum length of single fragment */
 100         TAILQ_HEAD(pf_fragq, pf_frent) fr_queue;
 101 };
 102
 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 static struct mtx pf_frag_mtx;
 111 #define PF_FRAG_LOCK()          mtx_lock(&pf_frag_mtx)
 112 #define PF_FRAG_UNLOCK()        mtx_unlock(&pf_frag_mtx)
 113 #define PF_FRAG_ASSERT()        mtx_assert(&pf_frag_mtx, MA_OWNED)
 114
 115 VNET_DEFINE(uma_zone_t, pf_state_scrub_z);      /* XXX: shared with pfsync */
 116
 117 static VNET_DEFINE(uma_zone_t, pf_frent_z);
 118 #define V_pf_frent_z    VNET(pf_frent_z)
 119 static VNET_DEFINE(uma_zone_t, pf_frag_z);
 120 #define V_pf_frag_z     VNET(pf_frag_z)
 121
 122 TAILQ_HEAD(pf_fragqueue, pf_fragment);
 123 TAILQ_HEAD(pf_cachequeue, pf_fragment);
 124 static VNET_DEFINE(struct pf_fragqueue, pf_fragqueue);
 125 #define V_pf_fragqueue                  VNET(pf_fragqueue)
 126 static VNET_DEFINE(struct pf_cachequeue,        pf_cachequeue);
 127 #define V_pf_cachequeue                 VNET(pf_cachequeue)
 128 RB_HEAD(pf_frag_tree, pf_fragment);
 129 static VNET_DEFINE(struct pf_frag_tree, pf_frag_tree);
 130 #define V_pf_frag_tree                  VNET(pf_frag_tree)
 131 static VNET_DEFINE(struct pf_frag_tree, pf_cache_tree);
 132 #define V_pf_cache_tree                 VNET(pf_cache_tree)
 133 static int               pf_frag_compare(struct pf_fragment *,
 134                             struct pf_fragment *);
 135 static RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 136 static RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 137
 138 static void     pf_flush_fragments(void);
 139 static void     pf_free_fragment(struct pf_fragment *);
 140 static void     pf_remove_fragment(struct pf_fragment *);
 141 static int      pf_normalize_tcpopt(struct pf_rule *, struct mbuf *,
 142                     struct tcphdr *, int, sa_family_t);
 143 static struct pf_frent *pf_create_fragment(u_short *);
 144 static struct pf_fragment *pf_find_fragment(struct pf_fragment_cmp *key,
 145                     struct pf_frag_tree *tree);
 146 static struct pf_fragment *pf_fillup_fragment(struct pf_fragment_cmp *,
 147                     struct pf_frent *, u_short *);
 148 static int      pf_isfull_fragment(struct pf_fragment *);
 149 static struct mbuf *pf_join_fragment(struct pf_fragment *);
 150 #ifdef INET
 151 static void     pf_scrub_ip(struct mbuf **, uint32_t, uint8_t, uint8_t);
 152 static int      pf_reassemble(struct mbuf **, struct ip *, int, u_short *);
 153 static struct mbuf *pf_fragcache(struct mbuf **, struct ip*,
 154                     struct pf_fragment **, int, int, int *);
 155 #endif  /* INET */
 156 #ifdef INET6
 157 static int      pf_reassemble6(struct mbuf **, struct ip6_hdr *,
 158                     struct ip6_frag *, uint16_t, uint16_t, int, u_short *);
 159 static void     pf_scrub_ip6(struct mbuf **, uint8_t);
 160 #endif  /* INET6 */
 161
 162 #define DPFPRINTF(x) do {                               \
 163         if (V_pf_status.debug >= PF_DEBUG_MISC) {       \
 164                 printf("%s: ", __func__);               \
 165                 printf x ;                              \
 166         }                                               \
 167 } while(0)
 168
 169 #ifdef INET
 170 static void
 171 pf_ip2key(struct ip *ip, int dir, struct pf_fragment_cmp *key)
 172 {
 173
 174         key->frc_src.v4 = ip->ip_src;
 175         key->frc_dst.v4 = ip->ip_dst;
 176         key->frc_af = AF_INET;
 177         key->frc_proto = ip->ip_p;
 178         key->frc_id = ip->ip_id;
 179         key->frc_direction = dir;
 180 }
 181 #endif  /* INET */
 182
 183 void
 184 pf_normalize_init(void)
 185 {
 186
 187         V_pf_frag_z = uma_zcreate("pf frags", sizeof(struct pf_fragment),
 188             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 189         V_pf_frent_z = uma_zcreate("pf frag entries", sizeof(struct pf_frent),
 190             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 191         V_pf_state_scrub_z = uma_zcreate("pf state scrubs",
 192             sizeof(struct pf_state_scrub),  NULL, NULL, NULL, NULL,
 193             UMA_ALIGN_PTR, 0);
 194
 195         V_pf_limits[PF_LIMIT_FRAGS].zone = V_pf_frent_z;
 196         V_pf_limits[PF_LIMIT_FRAGS].limit = PFFRAG_FRENT_HIWAT;
 197         uma_zone_set_max(V_pf_frent_z, PFFRAG_FRENT_HIWAT);
 198         uma_zone_set_warning(V_pf_frent_z, "PF frag entries limit reached");
 199
 200         mtx_init(&pf_frag_mtx, "pf fragments", NULL, MTX_DEF);
 201
 202         TAILQ_INIT(&V_pf_fragqueue);
 203         TAILQ_INIT(&V_pf_cachequeue);
 204 }
 205
 206 void
 207 pf_normalize_cleanup(void)
 208 {
 209
 210         uma_zdestroy(V_pf_state_scrub_z);
 211         uma_zdestroy(V_pf_frent_z);
 212         uma_zdestroy(V_pf_frag_z);
 213
 214         mtx_destroy(&pf_frag_mtx);
 215 }
 216
 217 static int
 218 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b)
 219 {
 220         int     diff;
 221
 222         if ((diff = a->fr_id - b->fr_id) != 0)
 223                 return (diff);
 224         if ((diff = a->fr_proto - b->fr_proto) != 0)
 225                 return (diff);
 226         if ((diff = a->fr_af - b->fr_af) != 0)
 227                 return (diff);
 228         if ((diff = pf_addr_cmp(&a->fr_src, &b->fr_src, a->fr_af)) != 0)
 229                 return (diff);
 230         if ((diff = pf_addr_cmp(&a->fr_dst, &b->fr_dst, a->fr_af)) != 0)
 231                 return (diff);
 232         return (0);
 233 }
 234
 235 void
 236 pf_purge_expired_fragments(void)
 237 {
 238         struct pf_fragment      *frag;
 239         u_int32_t                expire = time_uptime -
 240                                     V_pf_default_rule.timeout[PFTM_FRAG];
 241
 242         PF_FRAG_LOCK();
 243         while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) {
 244                 KASSERT((BUFFER_FRAGMENTS(frag)),
 245                     ("BUFFER_FRAGMENTS(frag) == 0: %s", __FUNCTION__));
 246                 if (frag->fr_timeout > expire)
 247                         break;
 248
 249                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 250                 pf_free_fragment(frag);
 251         }
 252
 253         while ((frag = TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue)) != NULL) {
 254                 KASSERT((!BUFFER_FRAGMENTS(frag)),
 255                     ("BUFFER_FRAGMENTS(frag) != 0: %s", __FUNCTION__));
 256                 if (frag->fr_timeout > expire)
 257                         break;
 258
 259                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 260                 pf_free_fragment(frag);
 261                 KASSERT((TAILQ_EMPTY(&V_pf_cachequeue) ||
 262                     TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue) != frag),
 263                     ("!(TAILQ_EMPTY() || TAILQ_LAST() == farg): %s",
 264                     __FUNCTION__));
 265         }
 266         PF_FRAG_UNLOCK();
 267 }
 268
 269 /*
 270  * Try to flush old fragments to make space for new ones
 271  */
 272 static void
 273 pf_flush_fragments(void)
 274 {
 275         struct pf_fragment      *frag, *cache;
 276         int                      goal;
 277
 278         PF_FRAG_ASSERT();
 279
 280         goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10;
 281         DPFPRINTF(("trying to free %d frag entriess\n", goal));
 282         while (goal < uma_zone_get_cur(V_pf_frent_z)) {
 283                 frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue);
 284                 if (frag)
 285                         pf_free_fragment(frag);
 286                 cache = TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue);
 287                 if (cache)
 288                         pf_free_fragment(cache);
 289                 if (frag == NULL && cache == NULL)
 290                         break;
 291         }
 292 }
 293
 294 /* Frees the fragments and all associated entries */
 295 static void
 296 pf_free_fragment(struct pf_fragment *frag)
 297 {
 298         struct pf_frent         *frent;
 299
 300         PF_FRAG_ASSERT();
 301
 302         /* Free all fragments */
 303         if (BUFFER_FRAGMENTS(frag)) {
 304                 for (frent = TAILQ_FIRST(&frag->fr_queue); frent;
 305                     frent = TAILQ_FIRST(&frag->fr_queue)) {
 306                         TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
 307
 308                         m_freem(frent->fe_m);
 309                         uma_zfree(V_pf_frent_z, frent);
 310                 }
 311         } else {
 312                 for (frent = TAILQ_FIRST(&frag->fr_queue); frent;
 313                     frent = TAILQ_FIRST(&frag->fr_queue)) {
 314                         TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
 315
 316                         KASSERT((TAILQ_EMPTY(&frag->fr_queue) ||
 317                             TAILQ_FIRST(&frag->fr_queue)->fe_off >
 318                             frent->fe_len),
 319                             ("! (TAILQ_EMPTY() || TAILQ_FIRST()->fe_off >"
 320                             " frent->fe_len): %s", __func__));
 321
 322                         uma_zfree(V_pf_frent_z, frent);
 323                 }
 324         }
 325
 326         pf_remove_fragment(frag);
 327 }
 328
 329 static struct pf_fragment *
 330 pf_find_fragment(struct pf_fragment_cmp *key, struct pf_frag_tree *tree)
 331 {
 332         struct pf_fragment      *frag;
 333
 334         PF_FRAG_ASSERT();
 335
 336         frag = RB_FIND(pf_frag_tree, tree, (struct pf_fragment *)key);
 337         if (frag != NULL) {
 338                 /* XXX Are we sure we want to update the timeout? */
 339                 frag->fr_timeout = time_uptime;
 340                 if (BUFFER_FRAGMENTS(frag)) {
 341                         TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 342                         TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
 343                 } else {
 344                         TAILQ_REMOVE(&V_pf_cachequeue, frag, frag_next);
 345                         TAILQ_INSERT_HEAD(&V_pf_cachequeue, frag, frag_next);
 346                 }
 347         }
 348
 349         return (frag);
 350 }
 351
 352 /* Removes a fragment from the fragment queue and frees the fragment */
 353 static void
 354 pf_remove_fragment(struct pf_fragment *frag)
 355 {
 356
 357         PF_FRAG_ASSERT();
 358
 359         if (BUFFER_FRAGMENTS(frag)) {
 360                 RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag);
 361                 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 362                 uma_zfree(V_pf_frag_z, frag);
 363         } else {
 364                 RB_REMOVE(pf_frag_tree, &V_pf_cache_tree, frag);
 365                 TAILQ_REMOVE(&V_pf_cachequeue, frag, frag_next);
 366                 uma_zfree(V_pf_frag_z, frag);
 367         }
 368 }
 369
 370 static struct pf_frent *
 371 pf_create_fragment(u_short *reason)
 372 {
 373         struct pf_frent *frent;
 374
 375         PF_FRAG_ASSERT();
 376
 377         frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 378         if (frent == NULL) {
 379                 pf_flush_fragments();
 380                 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 381                 if (frent == NULL) {
 382                         REASON_SET(reason, PFRES_MEMORY);
 383                         return (NULL);
 384                 }
 385         }
 386
 387         return (frent);
 388 }
 389
 390 struct pf_fragment *
 391 pf_fillup_fragment(struct pf_fragment_cmp *key, struct pf_frent *frent,
 392                 u_short *reason)
 393 {
 394         struct pf_frent         *after, *next, *prev;
 395         struct pf_fragment      *frag;
 396         uint16_t                total;
 397
 398         PF_FRAG_ASSERT();
 399
 400         /* No empty fragments. */
 401         if (frent->fe_len == 0) {
 402                 DPFPRINTF(("bad fragment: len 0"));
 403                 goto bad_fragment;
 404         }
 405
 406         /* All fragments are 8 byte aligned. */
 407         if (frent->fe_mff && (frent->fe_len & 0x7)) {
 408                 DPFPRINTF(("bad fragment: mff and len %d", frent->fe_len));
 409                 goto bad_fragment;
 410         }
 411
 412         /* Respect maximum length, IP_MAXPACKET == IPV6_MAXPACKET. */
 413         if (frent->fe_off + frent->fe_len > IP_MAXPACKET) {
 414                 DPFPRINTF(("bad fragment: max packet %d",
 415                     frent->fe_off + frent->fe_len));
 416                 goto bad_fragment;
 417         }
 418
 419         DPFPRINTF((key->frc_af == AF_INET ?
 420             "reass frag %d @ %d-%d" : "reass frag %#08x @ %d-%d",
 421             key->frc_id, frent->fe_off, frent->fe_off + frent->fe_len));
 422
 423         /* Fully buffer all of the fragments in this fragment queue. */
 424         frag = pf_find_fragment(key, &V_pf_frag_tree);
 425
 426         /* Create a new reassembly queue for this packet. */
 427         if (frag == NULL) {
 428                 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 429                 if (frag == NULL) {
 430                         pf_flush_fragments();
 431                         frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 432                         if (frag == NULL) {
 433                                 REASON_SET(reason, PFRES_MEMORY);
 434                                 goto drop_fragment;
 435                         }
 436                 }
 437
 438                 *(struct pf_fragment_cmp *)frag = *key;
 439                 frag->fr_timeout = time_second;
 440                 frag->fr_maxlen = frent->fe_len;
 441                 TAILQ_INIT(&frag->fr_queue);
 442
 443                 RB_INSERT(pf_frag_tree, &V_pf_frag_tree, frag);
 444                 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
 445
 446                 /* We do not have a previous fragment. */
 447                 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next);
 448
 449                 return (frag);
 450         }
 451
 452         KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue"));
 453
 454         /* Remember maximum fragment len for refragmentation. */
 455         if (frent->fe_len > frag->fr_maxlen)
 456                 frag->fr_maxlen = frent->fe_len;
 457
 458         /* Maximum data we have seen already. */
 459         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 460                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 461
 462         /* Non terminal fragments must have more fragments flag. */
 463         if (frent->fe_off + frent->fe_len < total && !frent->fe_mff)
 464                 goto bad_fragment;
 465
 466         /* Check if we saw the last fragment already. */
 467         if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) {
 468                 if (frent->fe_off + frent->fe_len > total ||
 469                     (frent->fe_off + frent->fe_len == total && frent->fe_mff))
 470                         goto bad_fragment;
 471         } else {
 472                 if (frent->fe_off + frent->fe_len == total && !frent->fe_mff)
 473                         goto bad_fragment;
 474         }
 475
 476         /* Find a fragment after the current one. */
 477         prev = NULL;
 478         TAILQ_FOREACH(after, &frag->fr_queue, fr_next) {
 479                 if (after->fe_off > frent->fe_off)
 480                         break;
 481                 prev = after;
 482         }
 483
 484         KASSERT(prev != NULL || after != NULL,
 485             ("prev != NULL || after != NULL"));
 486
 487         if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) {
 488                 uint16_t precut;
 489
 490                 precut = prev->fe_off + prev->fe_len - frent->fe_off;
 491                 if (precut >= frent->fe_len)
 492                         goto bad_fragment;
 493                 DPFPRINTF(("overlap -%d", precut));
 494                 m_adj(frent->fe_m, precut);
 495                 frent->fe_off += precut;
 496                 frent->fe_len -= precut;
 497         }
 498
 499         for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off;
 500             after = next) {
 501                 uint16_t aftercut;
 502
 503                 aftercut = frent->fe_off + frent->fe_len - after->fe_off;
 504                 DPFPRINTF(("adjust overlap %d", aftercut));
 505                 if (aftercut < after->fe_len) {
 506                         m_adj(after->fe_m, aftercut);
 507                         after->fe_off += aftercut;
 508                         after->fe_len -= aftercut;
 509                         break;
 510                 }
 511
 512                 /* This fragment is completely overlapped, lose it. */
 513                 next = TAILQ_NEXT(after, fr_next);
 514                 m_freem(after->fe_m);
 515                 TAILQ_REMOVE(&frag->fr_queue, after, fr_next);
 516                 uma_zfree(V_pf_frent_z, after);
 517         }
 518
 519         if (prev == NULL)
 520                 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next);
 521         else
 522                 TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next);
 523
 524         return (frag);
 525
 526 bad_fragment:
 527         REASON_SET(reason, PFRES_FRAG);
 528 drop_fragment:
 529         uma_zfree(V_pf_frent_z, frent);
 530         return (NULL);
 531 }
 532
 533 static int
 534 pf_isfull_fragment(struct pf_fragment *frag)
 535 {
 536         struct pf_frent *frent, *next;
 537         uint16_t off, total;
 538
 539         /* Check if we are completely reassembled */
 540         if (TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff)
 541                 return (0);
 542
 543         /* Maximum data we have seen already */
 544         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 545                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 546
 547         /* Check if we have all the data */
 548         off = 0;
 549         for (frent = TAILQ_FIRST(&frag->fr_queue); frent; frent = next) {
 550                 next = TAILQ_NEXT(frent, fr_next);
 551
 552                 off += frent->fe_len;
 553                 if (off < total && (next == NULL || next->fe_off != off)) {
 554                         DPFPRINTF(("missing fragment at %d, next %d, total %d",
 555                             off, next == NULL ? -1 : next->fe_off, total));
 556                         return (0);
 557                 }
 558         }
 559         DPFPRINTF(("%d < %d?", off, total));
 560         if (off < total)
 561                 return (0);
 562         KASSERT(off == total, ("off == total"));
 563
 564         return (1);
 565 }
 566
 567 static struct mbuf *
 568 pf_join_fragment(struct pf_fragment *frag)
 569 {
 570         struct mbuf *m, *m2;
 571         struct pf_frent *frent, *next;
 572
 573         frent = TAILQ_FIRST(&frag->fr_queue);
 574         next = TAILQ_NEXT(frent, fr_next);
 575
 576         m = frent->fe_m;
 577         m_adj(m, (frent->fe_hdrlen + frent->fe_len) - m->m_pkthdr.len);
 578         uma_zfree(V_pf_frent_z, frent);
 579         for (frent = next; frent != NULL; frent = next) {
 580                 next = TAILQ_NEXT(frent, fr_next);
 581
 582                 m2 = frent->fe_m;
 583                 /* Strip off ip header. */
 584                 m_adj(m2, frent->fe_hdrlen);
 585                 /* Strip off any trailing bytes. */
 586                 m_adj(m2, frent->fe_len - m2->m_pkthdr.len);
 587
 588                 uma_zfree(V_pf_frent_z, frent);
 589                 m_cat(m, m2);
 590         }
 591
 592         /* Remove from fragment queue. */
 593         pf_remove_fragment(frag);
 594
 595         return (m);
 596 }
 597
 598 #ifdef INET
 599 static int
 600 pf_reassemble(struct mbuf **m0, struct ip *ip, int dir, u_short *reason)
 601 {
 602         struct mbuf             *m = *m0;
 603         struct pf_frent         *frent;
 604         struct pf_fragment      *frag;
 605         struct pf_fragment_cmp  key;
 606         uint16_t                total, hdrlen;
 607
 608         /* Get an entry for the fragment queue */
 609         if ((frent = pf_create_fragment(reason)) == NULL)
 610                 return (PF_DROP);
 611
 612         frent->fe_m = m;
 613         frent->fe_hdrlen = ip->ip_hl << 2;
 614         frent->fe_extoff = 0;
 615         frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2);
 616         frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3;
 617         frent->fe_mff = ntohs(ip->ip_off) & IP_MF;
 618
 619         pf_ip2key(ip, dir, &key);
 620
 621         if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL)
 622                 return (PF_DROP);
 623
 624         /* The mbuf is part of the fragment entry, no direct free or access */
 625         m = *m0 = NULL;
 626
 627         if (!pf_isfull_fragment(frag))
 628                 return (PF_PASS);  /* drop because *m0 is NULL, no error */
 629
 630         /* We have all the data */
 631         frent = TAILQ_FIRST(&frag->fr_queue);
 632         KASSERT(frent != NULL, ("frent != NULL"));
 633         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 634                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 635         hdrlen = frent->fe_hdrlen;
 636
 637         m = *m0 = pf_join_fragment(frag);
 638         frag = NULL;
 639
 640         if (m->m_flags & M_PKTHDR) {
 641                 int plen = 0;
 642                 for (m = *m0; m; m = m->m_next)
 643                         plen += m->m_len;
 644                 m = *m0;
 645                 m->m_pkthdr.len = plen;
 646         }
 647
 648         ip = mtod(m, struct ip *);
 649         ip->ip_len = htons(hdrlen + total);
 650         ip->ip_off &= ~(IP_MF|IP_OFFMASK);
 651
 652         if (hdrlen + total > IP_MAXPACKET) {
 653                 DPFPRINTF(("drop: too big: %d", total));
 654                 ip->ip_len = 0;
 655                 REASON_SET(reason, PFRES_SHORT);
 656                 /* PF_DROP requires a valid mbuf *m0 in pf_test() */
 657                 return (PF_DROP);
 658         }
 659
 660         DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len)));
 661         return (PF_PASS);
 662 }
 663 #endif  /* INET */
 664
 665 #ifdef INET6
 666 static int
 667 pf_reassemble6(struct mbuf **m0, struct ip6_hdr *ip6, struct ip6_frag *fraghdr,
 668     uint16_t hdrlen, uint16_t extoff, int dir, u_short *reason)
 669 {
 670         struct mbuf             *m = *m0;
 671         struct pf_frent         *frent;
 672         struct pf_fragment      *frag;
 673         struct pf_fragment_cmp   key;
 674         struct m_tag            *mtag;
 675         struct pf_fragment_tag  *ftag;
 676         int                      off;
 677         uint32_t                 frag_id;
 678         uint16_t                 total, maxlen;
 679         uint8_t                  proto;
 680
 681         PF_FRAG_LOCK();
 682
 683         /* Get an entry for the fragment queue. */
 684         if ((frent = pf_create_fragment(reason)) == NULL) {
 685                 PF_FRAG_UNLOCK();
 686                 return (PF_DROP);
 687         }
 688
 689         frent->fe_m = m;
 690         frent->fe_hdrlen = hdrlen;
 691         frent->fe_extoff = extoff;
 692         frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen;
 693         frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK);
 694         frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG;
 695
 696         key.frc_src.v6 = ip6->ip6_src;
 697         key.frc_dst.v6 = ip6->ip6_dst;
 698         key.frc_af = AF_INET6;
 699         /* Only the first fragment's protocol is relevant. */
 700         key.frc_proto = 0;
 701         key.frc_id = fraghdr->ip6f_ident;
 702         key.frc_direction = dir;
 703
 704         if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) {
 705                 PF_FRAG_UNLOCK();
 706                 return (PF_DROP);
 707         }
 708
 709         /* The mbuf is part of the fragment entry, no direct free or access. */
 710         m = *m0 = NULL;
 711
 712         if (!pf_isfull_fragment(frag)) {
 713                 PF_FRAG_UNLOCK();
 714                 return (PF_PASS);  /* Drop because *m0 is NULL, no error. */
 715         }
 716
 717         /* We have all the data. */
 718         extoff = frent->fe_extoff;
 719         maxlen = frag->fr_maxlen;
 720         frag_id = frag->fr_id;
 721         frent = TAILQ_FIRST(&frag->fr_queue);
 722         KASSERT(frent != NULL, ("frent != NULL"));
 723         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 724                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 725         hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag);
 726
 727         m = *m0 = pf_join_fragment(frag);
 728         frag = NULL;
 729
 730         PF_FRAG_UNLOCK();
 731
 732         /* Take protocol from first fragment header. */
 733         m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off);
 734         KASSERT(m, ("%s: short mbuf chain", __func__));
 735         proto = *(mtod(m, caddr_t) + off);
 736         m = *m0;
 737
 738         /* Delete frag6 header */
 739         if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0)
 740                 goto fail;
 741
 742         if (m->m_flags & M_PKTHDR) {
 743                 int plen = 0;
 744                 for (m = *m0; m; m = m->m_next)
 745                         plen += m->m_len;
 746                 m = *m0;
 747                 m->m_pkthdr.len = plen;
 748         }
 749
 750         if ((mtag = m_tag_get(PF_REASSEMBLED, sizeof(struct pf_fragment_tag),
 751             M_NOWAIT)) == NULL)
 752                 goto fail;
 753         ftag = (struct pf_fragment_tag *)(mtag + 1);
 754         ftag->ft_hdrlen = hdrlen;
 755         ftag->ft_extoff = extoff;
 756         ftag->ft_maxlen = maxlen;
 757         ftag->ft_id = frag_id;
 758         m_tag_prepend(m, mtag);
 759
 760         ip6 = mtod(m, struct ip6_hdr *);
 761         ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total);
 762         if (extoff) {
 763                 /* Write protocol into next field of last extension header. */
 764                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
 765                     &off);
 766                 KASSERT(m, ("%s: short mbuf chain", __func__));
 767                 *(mtod(m, char *) + off) = proto;
 768                 m = *m0;
 769         } else
 770                 ip6->ip6_nxt = proto;
 771
 772         if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) {
 773                 DPFPRINTF(("drop: too big: %d", total));
 774                 ip6->ip6_plen = 0;
 775                 REASON_SET(reason, PFRES_SHORT);
 776                 /* PF_DROP requires a valid mbuf *m0 in pf_test6(). */
 777                 return (PF_DROP);
 778         }
 779
 780         DPFPRINTF(("complete: %p(%d)", m, ntohs(ip6->ip6_plen)));
 781         return (PF_PASS);
 782
 783 fail:
 784         REASON_SET(reason, PFRES_MEMORY);
 785         /* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */
 786         return (PF_DROP);
 787 }
 788 #endif  /* INET6 */
 789
 790 #ifdef INET
 791 static struct mbuf *
 792 pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff,
 793     int drop, int *nomem)
 794 {
 795         struct mbuf             *m = *m0;
 796         struct pf_frent         *frp, *fra, *cur = NULL;
 797         int                      ip_len = ntohs(h->ip_len) - (h->ip_hl << 2);
 798         u_int16_t                off = ntohs(h->ip_off) << 3;
 799         u_int16_t                max = ip_len + off;
 800         int                      hosed = 0;
 801
 802         PF_FRAG_ASSERT();
 803         KASSERT((*frag == NULL || !BUFFER_FRAGMENTS(*frag)),
 804             ("!(*frag == NULL || !BUFFER_FRAGMENTS(*frag)): %s", __FUNCTION__));
 805
 806         /* Create a new range queue for this packet */
 807         if (*frag == NULL) {
 808                 *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 809                 if (*frag == NULL) {
 810                         pf_flush_fragments();
 811                         *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 812                         if (*frag == NULL)
 813                                 goto no_mem;
 814                 }
 815
 816                 /* Get an entry for the queue */
 817                 cur = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 818                 if (cur == NULL) {
 819                         uma_zfree(V_pf_frag_z, *frag);
 820                         *frag = NULL;
 821                         goto no_mem;
 822                 }
 823
 824                 (*frag)->fr_flags = PFFRAG_NOBUFFER;
 825                 (*frag)->fr_max = 0;
 826                 (*frag)->fr_src.v4 = h->ip_src;
 827                 (*frag)->fr_dst.v4 = h->ip_dst;
 828                 (*frag)->fr_id = h->ip_id;
 829                 (*frag)->fr_timeout = time_uptime;
 830
 831                 cur->fe_off = off;
 832                 cur->fe_len = max; /* TODO: fe_len = max - off ? */
 833                 TAILQ_INIT(&(*frag)->fr_queue);
 834                 TAILQ_INSERT_HEAD(&(*frag)->fr_queue, cur, fr_next);
 835
 836                 RB_INSERT(pf_frag_tree, &V_pf_cache_tree, *frag);
 837                 TAILQ_INSERT_HEAD(&V_pf_cachequeue, *frag, frag_next);
 838
 839                 DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max));
 840
 841                 goto pass;
 842         }
 843
 844         /*
 845          * Find a fragment after the current one:
 846          *  - off contains the real shifted offset.
 847          */
 848         frp = NULL;
 849         TAILQ_FOREACH(fra, &(*frag)->fr_queue, fr_next) {
 850                 if (fra->fe_off > off)
 851                         break;
 852                 frp = fra;
 853         }
 854
 855         KASSERT((frp != NULL || fra != NULL),
 856             ("!(frp != NULL || fra != NULL): %s", __FUNCTION__));
 857
 858         if (frp != NULL) {
 859                 int     precut;
 860
 861                 precut = frp->fe_len - off;
 862                 if (precut >= ip_len) {
 863                         /* Fragment is entirely a duplicate */
 864                         DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n",
 865                             h->ip_id, frp->fe_off, frp->fe_len, off, max));
 866                         goto drop_fragment;
 867                 }
 868                 if (precut == 0) {
 869                         /* They are adjacent.  Fixup cache entry */
 870                         DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n",
 871                             h->ip_id, frp->fe_off, frp->fe_len, off, max));
 872                         frp->fe_len = max;
 873                 } else if (precut > 0) {
 874                         /* The first part of this payload overlaps with a
 875                          * fragment that has already been passed.
 876                          * Need to trim off the first part of the payload.
 877                          * But to do so easily, we need to create another
 878                          * mbuf to throw the original header into.
 879                          */
 880
 881                         DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n",
 882                             h->ip_id, precut, frp->fe_off, frp->fe_len, off,
 883                             max));
 884
 885                         off += precut;
 886                         max -= precut;
 887                         /* Update the previous frag to encompass this one */
 888                         frp->fe_len = max;
 889
 890                         if (!drop) {
 891                                 /* XXX Optimization opportunity
 892                                  * This is a very heavy way to trim the payload.
 893                                  * we could do it much faster by diddling mbuf
 894                                  * internals but that would be even less legible
 895                                  * than this mbuf magic.  For my next trick,
 896                                  * I'll pull a rabbit out of my laptop.
 897                                  */
 898                                 *m0 = m_dup(m, M_NOWAIT);
 899                                 if (*m0 == NULL)
 900                                         goto no_mem;
 901                                 /* From KAME Project : We have missed this! */
 902                                 m_adj(*m0, (h->ip_hl << 2) -
 903                                     (*m0)->m_pkthdr.len);
 904
 905                                 KASSERT(((*m0)->m_next == NULL),
 906                                     ("(*m0)->m_next != NULL: %s",
 907                                     __FUNCTION__));
 908                                 m_adj(m, precut + (h->ip_hl << 2));
 909                                 m_cat(*m0, m);
 910                                 m = *m0;
 911                                 if (m->m_flags & M_PKTHDR) {
 912                                         int plen = 0;
 913                                         struct mbuf *t;
 914                                         for (t = m; t; t = t->m_next)
 915                                                 plen += t->m_len;
 916                                         m->m_pkthdr.len = plen;
 917                                 }
 918
 919
 920                                 h = mtod(m, struct ip *);
 921
 922                                 KASSERT(((int)m->m_len ==
 923                                     ntohs(h->ip_len) - precut),
 924                                     ("m->m_len != ntohs(h->ip_len) - precut: %s",
 925                                     __FUNCTION__));
 926                                 h->ip_off = htons(ntohs(h->ip_off) +
 927                                     (precut >> 3));
 928                                 h->ip_len = htons(ntohs(h->ip_len) - precut);
 929                         } else {
 930                                 hosed++;
 931                         }
 932                 } else {
 933                         /* There is a gap between fragments */
 934
 935                         DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n",
 936                             h->ip_id, -precut, frp->fe_off, frp->fe_len, off,
 937                             max));
 938
 939                         cur = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 940                         if (cur == NULL)
 941                                 goto no_mem;
 942
 943                         cur->fe_off = off;
 944                         cur->fe_len = max;
 945                         TAILQ_INSERT_AFTER(&(*frag)->fr_queue, frp, cur, fr_next);
 946                 }
 947         }
 948
 949         if (fra != NULL) {
 950                 int     aftercut;
 951                 int     merge = 0;
 952
 953                 aftercut = max - fra->fe_off;
 954                 if (aftercut == 0) {
 955                         /* Adjacent fragments */
 956                         DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n",
 957                             h->ip_id, off, max, fra->fe_off, fra->fe_len));
 958                         fra->fe_off = off;
 959                         merge = 1;
 960                 } else if (aftercut > 0) {
 961                         /* Need to chop off the tail of this fragment */
 962                         DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n",
 963                             h->ip_id, aftercut, off, max, fra->fe_off,
 964                             fra->fe_len));
 965                         fra->fe_off = off;
 966                         max -= aftercut;
 967
 968                         merge = 1;
 969
 970                         if (!drop) {
 971                                 m_adj(m, -aftercut);
 972                                 if (m->m_flags & M_PKTHDR) {
 973                                         int plen = 0;
 974                                         struct mbuf *t;
 975                                         for (t = m; t; t = t->m_next)
 976                                                 plen += t->m_len;
 977                                         m->m_pkthdr.len = plen;
 978                                 }
 979                                 h = mtod(m, struct ip *);
 980                                 KASSERT(((int)m->m_len == ntohs(h->ip_len) - aftercut),
 981                                     ("m->m_len != ntohs(h->ip_len) - aftercut: %s",
 982                                     __FUNCTION__));
 983                                 h->ip_len = htons(ntohs(h->ip_len) - aftercut);
 984                         } else {
 985                                 hosed++;
 986                         }
 987                 } else if (frp == NULL) {
 988                         /* There is a gap between fragments */
 989                         DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n",
 990                             h->ip_id, -aftercut, off, max, fra->fe_off,
 991                             fra->fe_len));
 992
 993                         cur = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 994                         if (cur == NULL)
 995                                 goto no_mem;
 996
 997                         cur->fe_off = off;
 998                         cur->fe_len = max;
 999                         TAILQ_INSERT_HEAD(&(*frag)->fr_queue, cur, fr_next);
1000                 }
1001
1002
1003                 /* Need to glue together two separate fragment descriptors */
1004                 if (merge) {
1005                         if (cur && fra->fe_off <= cur->fe_len) {
1006                                 /* Need to merge in a previous 'cur' */
1007                                 DPFPRINTF(("fragcache[%d]: adjacent(merge "
1008                                     "%d-%d) %d-%d (%d-%d)\n",
1009                                     h->ip_id, cur->fe_off, cur->fe_len, off,
1010                                     max, fra->fe_off, fra->fe_len));
1011                                 fra->fe_off = cur->fe_off;
1012                                 TAILQ_REMOVE(&(*frag)->fr_queue, cur, fr_next);
1013                                 uma_zfree(V_pf_frent_z, cur);
1014                                 cur = NULL;
1015
1016                         } else if (frp && fra->fe_off <= frp->fe_len) {
1017                                 /* Need to merge in a modified 'frp' */
1018                                 KASSERT((cur == NULL), ("cur != NULL: %s",
1019                                     __FUNCTION__));
1020                                 DPFPRINTF(("fragcache[%d]: adjacent(merge "
1021                                     "%d-%d) %d-%d (%d-%d)\n",
1022                                     h->ip_id, frp->fe_off, frp->fe_len, off,
1023                                     max, fra->fe_off, fra->fe_len));
1024                                 fra->fe_off = frp->fe_off;
1025                                 TAILQ_REMOVE(&(*frag)->fr_queue, frp, fr_next);
1026                                 uma_zfree(V_pf_frent_z, frp);
1027                                 frp = NULL;
1028
1029                         }
1030                 }
1031         }
1032
1033         if (hosed) {
1034                 /*
1035                  * We must keep tracking the overall fragment even when
1036                  * we're going to drop it anyway so that we know when to
1037                  * free the overall descriptor.  Thus we drop the frag late.
1038                  */
1039                 goto drop_fragment;
1040         }
1041
1042
1043  pass:
1044         /* Update maximum data size */
1045         if ((*frag)->fr_max < max)
1046                 (*frag)->fr_max = max;
1047
1048         /* This is the last segment */
1049         if (!mff)
1050                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
1051
1052         /* Check if we are completely reassembled */
1053         if (((*frag)->fr_flags & PFFRAG_SEENLAST) &&
1054             TAILQ_FIRST(&(*frag)->fr_queue)->fe_off == 0 &&
1055             TAILQ_FIRST(&(*frag)->fr_queue)->fe_len == (*frag)->fr_max) {
1056                 /* Remove from fragment queue */
1057                 DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id,
1058                     (*frag)->fr_max));
1059                 pf_free_fragment(*frag);
1060                 *frag = NULL;
1061         }
1062
1063         return (m);
1064
1065  no_mem:
1066         *nomem = 1;
1067
1068         /* Still need to pay attention to !IP_MF */
1069         if (!mff && *frag != NULL)
1070                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
1071
1072         m_freem(m);
1073         return (NULL);
1074
1075  drop_fragment:
1076
1077         /* Still need to pay attention to !IP_MF */
1078         if (!mff && *frag != NULL)
1079                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
1080
1081         if (drop) {
1082                 /* This fragment has been deemed bad.  Don't reass */
1083                 if (((*frag)->fr_flags & PFFRAG_DROP) == 0)
1084                         DPFPRINTF(("fragcache[%d]: dropping overall fragment\n",
1085                             h->ip_id));
1086                 (*frag)->fr_flags |= PFFRAG_DROP;
1087         }
1088
1089         m_freem(m);
1090         return (NULL);
1091 }
1092 #endif  /* INET */
1093
1094 #ifdef INET6
1095 int
1096 pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag)
1097 {
1098         struct mbuf             *m = *m0, *t;
1099         struct pf_fragment_tag  *ftag = (struct pf_fragment_tag *)(mtag + 1);
1100         struct pf_pdesc          pd;
1101         uint32_t                 frag_id;
1102         uint16_t                 hdrlen, extoff, maxlen;
1103         uint8_t                  proto;
1104         int                      error, action;
1105
1106         hdrlen = ftag->ft_hdrlen;
1107         extoff = ftag->ft_extoff;
1108         maxlen = ftag->ft_maxlen;
1109         frag_id = ftag->ft_id;
1110         m_tag_delete(m, mtag);
1111         mtag = NULL;
1112         ftag = NULL;
1113
1114         if (extoff) {
1115                 int off;
1116
1117                 /* Use protocol from next field of last extension header */
1118                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
1119                     &off);
1120                 KASSERT((m != NULL), ("pf_refragment6: short mbuf chain"));
1121                 proto = *(mtod(m, caddr_t) + off);
1122                 *(mtod(m, char *) + off) = IPPROTO_FRAGMENT;
1123                 m = *m0;
1124         } else {
1125                 struct ip6_hdr *hdr;
1126
1127                 hdr = mtod(m, struct ip6_hdr *);
1128                 proto = hdr->ip6_nxt;
1129                 hdr->ip6_nxt = IPPROTO_FRAGMENT;
1130         }
1131
1132         /*
1133          * Maxlen may be less than 8 if there was only a single
1134          * fragment.  As it was fragmented before, add a fragment
1135          * header also for a single fragment.  If total or maxlen
1136          * is less than 8, ip6_fragment() will return EMSGSIZE and
1137          * we drop the packet.
1138          */
1139         error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id);
1140         m = (*m0)->m_nextpkt;
1141         (*m0)->m_nextpkt = NULL;
1142         if (error == 0) {
1143                 /* The first mbuf contains the unfragmented packet. */
1144                 m_freem(*m0);
1145                 *m0 = NULL;
1146                 action = PF_PASS;
1147         } else {
1148                 /* Drop expects an mbuf to free. */
1149                 DPFPRINTF(("refragment error %d", error));
1150                 action = PF_DROP;
1151         }
1152         for (t = m; m; m = t) {
1153                 t = m->m_nextpkt;
1154                 m->m_nextpkt = NULL;
1155                 m->m_flags |= M_SKIP_FIREWALL;
1156                 memset(&pd, 0, sizeof(pd));
1157                 pd.pf_mtag = pf_find_mtag(m);
1158                 if (error == 0)
1159                         ip6_forward(m, 0);
1160                 else
1161                         m_freem(m);
1162         }
1163
1164         return (action);
1165 }
1166 #endif /* INET6 */
1167
1168 #ifdef INET
1169 int
1170 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason,
1171     struct pf_pdesc *pd)
1172 {
1173         struct mbuf             *m = *m0;
1174         struct pf_rule          *r;
1175         struct pf_fragment      *frag = NULL;
1176         struct pf_fragment_cmp  key;
1177         struct ip               *h = mtod(m, struct ip *);
1178         int                      mff = (ntohs(h->ip_off) & IP_MF);
1179         int                      hlen = h->ip_hl << 2;
1180         u_int16_t                fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
1181         u_int16_t                max;
1182         int                      ip_len;
1183         int                      ip_off;
1184         int                      tag = -1;
1185         int                      verdict;
1186
1187         PF_RULES_RASSERT();
1188
1189         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1190         while (r != NULL) {
1191                 r->evaluations++;
1192                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1193                         r = r->skip[PF_SKIP_IFP].ptr;
1194                 else if (r->direction && r->direction != dir)
1195                         r = r->skip[PF_SKIP_DIR].ptr;
1196                 else if (r->af && r->af != AF_INET)
1197                         r = r->skip[PF_SKIP_AF].ptr;
1198                 else if (r->proto && r->proto != h->ip_p)
1199                         r = r->skip[PF_SKIP_PROTO].ptr;
1200                 else if (PF_MISMATCHAW(&r->src.addr,
1201                     (struct pf_addr *)&h->ip_src.s_addr, AF_INET,
1202                     r->src.neg, kif, M_GETFIB(m)))
1203                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1204                 else if (PF_MISMATCHAW(&r->dst.addr,
1205                     (struct pf_addr *)&h->ip_dst.s_addr, AF_INET,
1206                     r->dst.neg, NULL, M_GETFIB(m)))
1207                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1208                 else if (r->match_tag && !pf_match_tag(m, r, &tag,
1209                     pd->pf_mtag ? pd->pf_mtag->tag : 0))
1210                         r = TAILQ_NEXT(r, entries);
1211                 else
1212                         break;
1213         }
1214
1215         if (r == NULL || r->action == PF_NOSCRUB)
1216                 return (PF_PASS);
1217         else {
1218                 r->packets[dir == PF_OUT]++;
1219                 r->bytes[dir == PF_OUT] += pd->tot_len;
1220         }
1221
1222         /* Check for illegal packets */
1223         if (hlen < (int)sizeof(struct ip))
1224                 goto drop;
1225
1226         if (hlen > ntohs(h->ip_len))
1227                 goto drop;
1228
1229         /* Clear IP_DF if the rule uses the no-df option */
1230         if (r->rule_flag & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
1231                 u_int16_t ip_off = h->ip_off;
1232
1233                 h->ip_off &= htons(~IP_DF);
1234                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1235         }
1236
1237         /* We will need other tests here */
1238         if (!fragoff && !mff)
1239                 goto no_fragment;
1240
1241         /* We're dealing with a fragment now. Don't allow fragments
1242          * with IP_DF to enter the cache. If the flag was cleared by
1243          * no-df above, fine. Otherwise drop it.
1244          */
1245         if (h->ip_off & htons(IP_DF)) {
1246                 DPFPRINTF(("IP_DF\n"));
1247                 goto bad;
1248         }
1249
1250         ip_len = ntohs(h->ip_len) - hlen;
1251         ip_off = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
1252
1253         /* All fragments are 8 byte aligned */
1254         if (mff && (ip_len & 0x7)) {
1255                 DPFPRINTF(("mff and %d\n", ip_len));
1256                 goto bad;
1257         }
1258
1259         /* Respect maximum length */
1260         if (fragoff + ip_len > IP_MAXPACKET) {
1261                 DPFPRINTF(("max packet %d\n", fragoff + ip_len));
1262                 goto bad;
1263         }
1264         max = fragoff + ip_len;
1265
1266         if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) {
1267
1268                 /* Fully buffer all of the fragments */
1269                 PF_FRAG_LOCK();
1270
1271                 pf_ip2key(h, dir, &key);
1272                 frag = pf_find_fragment(&key, &V_pf_frag_tree);
1273
1274                 /* Check if we saw the last fragment already */
1275                 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
1276                     max > frag->fr_max)
1277                         goto bad;
1278
1279                 /* Might return a completely reassembled mbuf, or NULL */
1280                 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
1281                 verdict = pf_reassemble(m0, h, dir, reason);
1282                 PF_FRAG_UNLOCK();
1283
1284                 if (verdict != PF_PASS)
1285                         return (PF_DROP);
1286
1287                 m = *m0;
1288                 if (m == NULL)
1289                         return (PF_DROP);
1290
1291                 /* use mtag from concatenated mbuf chain */
1292                 pd->pf_mtag = pf_find_mtag(m);
1293 #ifdef DIAGNOSTIC
1294                 if (pd->pf_mtag == NULL) {
1295                         printf("%s: pf_find_mtag returned NULL(1)\n", __func__);
1296                         if ((pd->pf_mtag = pf_get_mtag(m)) == NULL) {
1297                                 m_freem(m);
1298                                 *m0 = NULL;
1299                                 goto no_mem;
1300                         }
1301                 }
1302 #endif
1303                 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
1304                         goto drop;
1305
1306                 h = mtod(m, struct ip *);
1307         } else {
1308                 /* non-buffering fragment cache (drops or masks overlaps) */
1309                 int     nomem = 0;
1310
1311                 if (dir == PF_OUT && pd->pf_mtag->flags & PF_TAG_FRAGCACHE) {
1312                         /*
1313                          * Already passed the fragment cache in the
1314                          * input direction.  If we continued, it would
1315                          * appear to be a dup and would be dropped.
1316                          */
1317                         goto fragment_pass;
1318                 }
1319
1320                 PF_FRAG_LOCK();
1321                 pf_ip2key(h, dir, &key);
1322                 frag = pf_find_fragment(&key, &V_pf_cache_tree);
1323
1324                 /* Check if we saw the last fragment already */
1325                 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
1326                     max > frag->fr_max) {
1327                         if (r->rule_flag & PFRULE_FRAGDROP)
1328                                 frag->fr_flags |= PFFRAG_DROP;
1329                         goto bad;
1330                 }
1331
1332                 *m0 = m = pf_fragcache(m0, h, &frag, mff,
1333                     (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem);
1334                 PF_FRAG_UNLOCK();
1335                 if (m == NULL) {
1336                         if (nomem)
1337                                 goto no_mem;
1338                         goto drop;
1339                 }
1340
1341                 /* use mtag from copied and trimmed mbuf chain */
1342                 pd->pf_mtag = pf_find_mtag(m);
1343 #ifdef DIAGNOSTIC
1344                 if (pd->pf_mtag == NULL) {
1345                         printf("%s: pf_find_mtag returned NULL(2)\n", __func__);
1346                         if ((pd->pf_mtag = pf_get_mtag(m)) == NULL) {
1347                                 m_freem(m);
1348                                 *m0 = NULL;
1349                                 goto no_mem;
1350                         }
1351                 }
1352 #endif
1353                 if (dir == PF_IN)
1354                         pd->pf_mtag->flags |= PF_TAG_FRAGCACHE;
1355
1356                 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
1357                         goto drop;
1358                 goto fragment_pass;
1359         }
1360
1361  no_fragment:
1362         /* At this point, only IP_DF is allowed in ip_off */
1363         if (h->ip_off & ~htons(IP_DF)) {
1364                 u_int16_t ip_off = h->ip_off;
1365
1366                 h->ip_off &= htons(IP_DF);
1367                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1368         }
1369
1370         /* not missing a return here */
1371
1372  fragment_pass:
1373         pf_scrub_ip(&m, r->rule_flag, r->min_ttl, r->set_tos);
1374
1375         if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0)
1376                 pd->flags |= PFDESC_IP_REAS;
1377         return (PF_PASS);
1378
1379  no_mem:
1380         REASON_SET(reason, PFRES_MEMORY);
1381         if (r != NULL && r->log)
1382                 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
1383                     1);
1384         return (PF_DROP);
1385
1386  drop:
1387         REASON_SET(reason, PFRES_NORM);
1388         if (r != NULL && r->log)
1389                 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
1390                     1);
1391         return (PF_DROP);
1392
1393  bad:
1394         DPFPRINTF(("dropping bad fragment\n"));
1395
1396         /* Free associated fragments */
1397         if (frag != NULL) {
1398                 pf_free_fragment(frag);
1399                 PF_FRAG_UNLOCK();
1400         }
1401
1402         REASON_SET(reason, PFRES_FRAG);
1403         if (r != NULL && r->log)
1404                 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
1405                     1);
1406
1407         return (PF_DROP);
1408 }
1409 #endif
1410
1411 #ifdef INET6
1412 int
1413 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif,
1414     u_short *reason, struct pf_pdesc *pd)
1415 {
1416         struct mbuf             *m = *m0;
1417         struct pf_rule          *r;
1418         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
1419         int                      extoff;
1420         int                      off;
1421         struct ip6_ext           ext;
1422         struct ip6_opt           opt;
1423         struct ip6_opt_jumbo     jumbo;
1424         struct ip6_frag          frag;
1425         u_int32_t                jumbolen = 0, plen;
1426         int                      optend;
1427         int                      ooff;
1428         u_int8_t                 proto;
1429         int                      terminal;
1430
1431         PF_RULES_RASSERT();
1432
1433         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1434         while (r != NULL) {
1435                 r->evaluations++;
1436                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1437                         r = r->skip[PF_SKIP_IFP].ptr;
1438                 else if (r->direction && r->direction != dir)
1439                         r = r->skip[PF_SKIP_DIR].ptr;
1440                 else if (r->af && r->af != AF_INET6)
1441                         r = r->skip[PF_SKIP_AF].ptr;
1442 #if 0 /* header chain! */
1443                 else if (r->proto && r->proto != h->ip6_nxt)
1444                         r = r->skip[PF_SKIP_PROTO].ptr;
1445 #endif
1446                 else if (PF_MISMATCHAW(&r->src.addr,
1447                     (struct pf_addr *)&h->ip6_src, AF_INET6,
1448                     r->src.neg, kif, M_GETFIB(m)))
1449                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1450                 else if (PF_MISMATCHAW(&r->dst.addr,
1451                     (struct pf_addr *)&h->ip6_dst, AF_INET6,
1452                     r->dst.neg, NULL, M_GETFIB(m)))
1453                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1454                 else
1455                         break;
1456         }
1457
1458         if (r == NULL || r->action == PF_NOSCRUB)
1459                 return (PF_PASS);
1460         else {
1461                 r->packets[dir == PF_OUT]++;
1462                 r->bytes[dir == PF_OUT] += pd->tot_len;
1463         }
1464
1465         /* Check for illegal packets */
1466         if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len)
1467                 goto drop;
1468
1469         extoff = 0;
1470         off = sizeof(struct ip6_hdr);
1471         proto = h->ip6_nxt;
1472         terminal = 0;
1473         do {
1474                 switch (proto) {
1475                 case IPPROTO_FRAGMENT:
1476                         goto fragment;
1477                         break;
1478                 case IPPROTO_AH:
1479                 case IPPROTO_ROUTING:
1480                 case IPPROTO_DSTOPTS:
1481                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1482                             NULL, AF_INET6))
1483                                 goto shortpkt;
1484                         extoff = off;
1485                         if (proto == IPPROTO_AH)
1486                                 off += (ext.ip6e_len + 2) * 4;
1487                         else
1488                                 off += (ext.ip6e_len + 1) * 8;
1489                         proto = ext.ip6e_nxt;
1490                         break;
1491                 case IPPROTO_HOPOPTS:
1492                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1493                             NULL, AF_INET6))
1494                                 goto shortpkt;
1495                         extoff = off;
1496                         optend = off + (ext.ip6e_len + 1) * 8;
1497                         ooff = off + sizeof(ext);
1498                         do {
1499                                 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type,
1500                                     sizeof(opt.ip6o_type), NULL, NULL,
1501                                     AF_INET6))
1502                                         goto shortpkt;
1503                                 if (opt.ip6o_type == IP6OPT_PAD1) {
1504                                         ooff++;
1505                                         continue;
1506                                 }
1507                                 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt),
1508                                     NULL, NULL, AF_INET6))
1509                                         goto shortpkt;
1510                                 if (ooff + sizeof(opt) + opt.ip6o_len > optend)
1511                                         goto drop;
1512                                 switch (opt.ip6o_type) {
1513                                 case IP6OPT_JUMBO:
1514                                         if (h->ip6_plen != 0)
1515                                                 goto drop;
1516                                         if (!pf_pull_hdr(m, ooff, &jumbo,
1517                                             sizeof(jumbo), NULL, NULL,
1518                                             AF_INET6))
1519                                                 goto shortpkt;
1520                                         memcpy(&jumbolen, jumbo.ip6oj_jumbo_len,
1521                                             sizeof(jumbolen));
1522                                         jumbolen = ntohl(jumbolen);
1523                                         if (jumbolen <= IPV6_MAXPACKET)
1524                                                 goto drop;
1525                                         if (sizeof(struct ip6_hdr) + jumbolen !=
1526                                             m->m_pkthdr.len)
1527                                                 goto drop;
1528                                         break;
1529                                 default:
1530                                         break;
1531                                 }
1532                                 ooff += sizeof(opt) + opt.ip6o_len;
1533                         } while (ooff < optend);
1534
1535                         off = optend;
1536                         proto = ext.ip6e_nxt;
1537                         break;
1538                 default:
1539                         terminal = 1;
1540                         break;
1541                 }
1542         } while (!terminal);
1543
1544         /* jumbo payload option must be present, or plen > 0 */
1545         if (ntohs(h->ip6_plen) == 0)
1546                 plen = jumbolen;
1547         else
1548                 plen = ntohs(h->ip6_plen);
1549         if (plen == 0)
1550                 goto drop;
1551         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1552                 goto shortpkt;
1553
1554         pf_scrub_ip6(&m, r->min_ttl);
1555
1556         return (PF_PASS);
1557
1558  fragment:
1559         /* Jumbo payload packets cannot be fragmented. */
1560         plen = ntohs(h->ip6_plen);
1561         if (plen == 0 || jumbolen)
1562                 goto drop;
1563         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1564                 goto shortpkt;
1565
1566         if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6))
1567                 goto shortpkt;
1568
1569         /* Offset now points to data portion. */
1570         off += sizeof(frag);
1571
1572         /* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */
1573         if (pf_reassemble6(m0, h, &frag, off, extoff, dir, reason) != PF_PASS)
1574                 return (PF_DROP);
1575         m = *m0;
1576         if (m == NULL)
1577                 return (PF_DROP);
1578
1579         pd->flags |= PFDESC_IP_REAS;
1580         return (PF_PASS);
1581
1582  shortpkt:
1583         REASON_SET(reason, PFRES_SHORT);
1584         if (r != NULL && r->log)
1585                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1586                     1);
1587         return (PF_DROP);
1588
1589  drop:
1590         REASON_SET(reason, PFRES_NORM);
1591         if (r != NULL && r->log)
1592                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1593                     1);
1594         return (PF_DROP);
1595 }
1596 #endif /* INET6 */
1597
1598 int
1599 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff,
1600     int off, void *h, struct pf_pdesc *pd)
1601 {
1602         struct pf_rule  *r, *rm = NULL;
1603         struct tcphdr   *th = pd->hdr.tcp;
1604         int              rewrite = 0;
1605         u_short          reason;
1606         u_int8_t         flags;
1607         sa_family_t      af = pd->af;
1608
1609         PF_RULES_RASSERT();
1610
1611         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1612         while (r != NULL) {
1613                 r->evaluations++;
1614                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1615                         r = r->skip[PF_SKIP_IFP].ptr;
1616                 else if (r->direction && r->direction != dir)
1617                         r = r->skip[PF_SKIP_DIR].ptr;
1618                 else if (r->af && r->af != af)
1619                         r = r->skip[PF_SKIP_AF].ptr;
1620                 else if (r->proto && r->proto != pd->proto)
1621                         r = r->skip[PF_SKIP_PROTO].ptr;
1622                 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af,
1623                     r->src.neg, kif, M_GETFIB(m)))
1624                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1625                 else if (r->src.port_op && !pf_match_port(r->src.port_op,
1626                             r->src.port[0], r->src.port[1], th->th_sport))
1627                         r = r->skip[PF_SKIP_SRC_PORT].ptr;
1628                 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af,
1629                     r->dst.neg, NULL, M_GETFIB(m)))
1630                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1631                 else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
1632                             r->dst.port[0], r->dst.port[1], th->th_dport))
1633                         r = r->skip[PF_SKIP_DST_PORT].ptr;
1634                 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match(
1635                             pf_osfp_fingerprint(pd, m, off, th),
1636                             r->os_fingerprint))
1637                         r = TAILQ_NEXT(r, entries);
1638                 else {
1639                         rm = r;
1640                         break;
1641                 }
1642         }
1643
1644         if (rm == NULL || rm->action == PF_NOSCRUB)
1645                 return (PF_PASS);
1646         else {
1647                 r->packets[dir == PF_OUT]++;
1648                 r->bytes[dir == PF_OUT] += pd->tot_len;
1649         }
1650
1651         if (rm->rule_flag & PFRULE_REASSEMBLE_TCP)
1652                 pd->flags |= PFDESC_TCP_NORM;
1653
1654         flags = th->th_flags;
1655         if (flags & TH_SYN) {
1656                 /* Illegal packet */
1657                 if (flags & TH_RST)
1658                         goto tcp_drop;
1659
1660                 if (flags & TH_FIN)
1661                         goto tcp_drop;
1662         } else {
1663                 /* Illegal packet */
1664                 if (!(flags & (TH_ACK|TH_RST)))
1665                         goto tcp_drop;
1666         }
1667
1668         if (!(flags & TH_ACK)) {
1669                 /* These flags are only valid if ACK is set */
1670                 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG))
1671                         goto tcp_drop;
1672         }
1673
1674         /* Check for illegal header length */
1675         if (th->th_off < (sizeof(struct tcphdr) >> 2))
1676                 goto tcp_drop;
1677
1678         /* If flags changed, or reserved data set, then adjust */
1679         if (flags != th->th_flags || th->th_x2 != 0) {
1680                 u_int16_t       ov, nv;
1681
1682                 ov = *(u_int16_t *)(&th->th_ack + 1);
1683                 th->th_flags = flags;
1684                 th->th_x2 = 0;
1685                 nv = *(u_int16_t *)(&th->th_ack + 1);
1686
1687                 th->th_sum = pf_cksum_fixup(th->th_sum, ov, nv, 0);
1688                 rewrite = 1;
1689         }
1690
1691         /* Remove urgent pointer, if TH_URG is not set */
1692         if (!(flags & TH_URG) && th->th_urp) {
1693                 th->th_sum = pf_cksum_fixup(th->th_sum, th->th_urp, 0, 0);
1694                 th->th_urp = 0;
1695                 rewrite = 1;
1696         }
1697
1698         /* Process options */
1699         if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af))
1700                 rewrite = 1;
1701
1702         /* copy back packet headers if we sanitized */
1703         if (rewrite)
1704                 m_copyback(m, off, sizeof(*th), (caddr_t)th);
1705
1706         return (PF_PASS);
1707
1708  tcp_drop:
1709         REASON_SET(&reason, PFRES_NORM);
1710         if (rm != NULL && r->log)
1711                 PFLOG_PACKET(kif, m, AF_INET, dir, reason, r, NULL, NULL, pd,
1712                     1);
1713         return (PF_DROP);
1714 }
1715
1716 int
1717 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd,
1718     struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst)
1719 {
1720         u_int32_t tsval, tsecr;
1721         u_int8_t hdr[60];
1722         u_int8_t *opt;
1723
1724         KASSERT((src->scrub == NULL),
1725             ("pf_normalize_tcp_init: src->scrub != NULL"));
1726
1727         src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT);
1728         if (src->scrub == NULL)
1729                 return (1);
1730
1731         switch (pd->af) {
1732 #ifdef INET
1733         case AF_INET: {
1734                 struct ip *h = mtod(m, struct ip *);
1735                 src->scrub->pfss_ttl = h->ip_ttl;
1736                 break;
1737         }
1738 #endif /* INET */
1739 #ifdef INET6
1740         case AF_INET6: {
1741                 struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1742                 src->scrub->pfss_ttl = h->ip6_hlim;
1743                 break;
1744         }
1745 #endif /* INET6 */
1746         }
1747
1748
1749         /*
1750          * All normalizations below are only begun if we see the start of
1751          * the connections.  They must all set an enabled bit in pfss_flags
1752          */
1753         if ((th->th_flags & TH_SYN) == 0)
1754                 return (0);
1755
1756
1757         if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub &&
1758             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1759                 /* Diddle with TCP options */
1760                 int hlen;
1761                 opt = hdr + sizeof(struct tcphdr);
1762                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1763                 while (hlen >= TCPOLEN_TIMESTAMP) {
1764                         switch (*opt) {
1765                         case TCPOPT_EOL:        /* FALLTHROUGH */
1766                         case TCPOPT_NOP:
1767                                 opt++;
1768                                 hlen--;
1769                                 break;
1770                         case TCPOPT_TIMESTAMP:
1771                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1772                                         src->scrub->pfss_flags |=
1773                                             PFSS_TIMESTAMP;
1774                                         src->scrub->pfss_ts_mod =
1775                                             htonl(arc4random());
1776
1777                                         /* note PFSS_PAWS not set yet */
1778                                         memcpy(&tsval, &opt[2],
1779                                             sizeof(u_int32_t));
1780                                         memcpy(&tsecr, &opt[6],
1781                                             sizeof(u_int32_t));
1782                                         src->scrub->pfss_tsval0 = ntohl(tsval);
1783                                         src->scrub->pfss_tsval = ntohl(tsval);
1784                                         src->scrub->pfss_tsecr = ntohl(tsecr);
1785                                         getmicrouptime(&src->scrub->pfss_last);
1786                                 }
1787                                 /* FALLTHROUGH */
1788                         default:
1789                                 hlen -= MAX(opt[1], 2);
1790                                 opt += MAX(opt[1], 2);
1791                                 break;
1792                         }
1793                 }
1794         }
1795
1796         return (0);
1797 }
1798
1799 void
1800 pf_normalize_tcp_cleanup(struct pf_state *state)
1801 {
1802         if (state->src.scrub)
1803                 uma_zfree(V_pf_state_scrub_z, state->src.scrub);
1804         if (state->dst.scrub)
1805                 uma_zfree(V_pf_state_scrub_z, state->dst.scrub);
1806
1807         /* Someday... flush the TCP segment reassembly descriptors. */
1808 }
1809
1810 int
1811 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd,
1812     u_short *reason, struct tcphdr *th, struct pf_state *state,
1813     struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback)
1814 {
1815         struct timeval uptime;
1816         u_int32_t tsval, tsecr;
1817         u_int tsval_from_last;
1818         u_int8_t hdr[60];
1819         u_int8_t *opt;
1820         int copyback = 0;
1821         int got_ts = 0;
1822
1823         KASSERT((src->scrub || dst->scrub),
1824             ("%s: src->scrub && dst->scrub!", __func__));
1825
1826         /*
1827          * Enforce the minimum TTL seen for this connection.  Negate a common
1828          * technique to evade an intrusion detection system and confuse
1829          * firewall state code.
1830          */
1831         switch (pd->af) {
1832 #ifdef INET
1833         case AF_INET: {
1834                 if (src->scrub) {
1835                         struct ip *h = mtod(m, struct ip *);
1836                         if (h->ip_ttl > src->scrub->pfss_ttl)
1837                                 src->scrub->pfss_ttl = h->ip_ttl;
1838                         h->ip_ttl = src->scrub->pfss_ttl;
1839                 }
1840                 break;
1841         }
1842 #endif /* INET */
1843 #ifdef INET6
1844         case AF_INET6: {
1845                 if (src->scrub) {
1846                         struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1847                         if (h->ip6_hlim > src->scrub->pfss_ttl)
1848                                 src->scrub->pfss_ttl = h->ip6_hlim;
1849                         h->ip6_hlim = src->scrub->pfss_ttl;
1850                 }
1851                 break;
1852         }
1853 #endif /* INET6 */
1854         }
1855
1856         if (th->th_off > (sizeof(struct tcphdr) >> 2) &&
1857             ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) ||
1858             (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) &&
1859             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1860                 /* Diddle with TCP options */
1861                 int hlen;
1862                 opt = hdr + sizeof(struct tcphdr);
1863                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1864                 while (hlen >= TCPOLEN_TIMESTAMP) {
1865                         switch (*opt) {
1866                         case TCPOPT_EOL:        /* FALLTHROUGH */
1867                         case TCPOPT_NOP:
1868                                 opt++;
1869                                 hlen--;
1870                                 break;
1871                         case TCPOPT_TIMESTAMP:
1872                                 /* Modulate the timestamps.  Can be used for
1873                                  * NAT detection, OS uptime determination or
1874                                  * reboot detection.
1875                                  */
1876
1877                                 if (got_ts) {
1878                                         /* Huh?  Multiple timestamps!? */
1879                                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1880                                                 DPFPRINTF(("multiple TS??"));
1881                                                 pf_print_state(state);
1882                                                 printf("\n");
1883                                         }
1884                                         REASON_SET(reason, PFRES_TS);
1885                                         return (PF_DROP);
1886                                 }
1887                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1888                                         memcpy(&tsval, &opt[2],
1889                                             sizeof(u_int32_t));
1890                                         if (tsval && src->scrub &&
1891                                             (src->scrub->pfss_flags &
1892                                             PFSS_TIMESTAMP)) {
1893                                                 tsval = ntohl(tsval);
1894                                                 pf_change_a(&opt[2],
1895                                                     &th->th_sum,
1896                                                     htonl(tsval +
1897                                                     src->scrub->pfss_ts_mod),
1898                                                     0);
1899                                                 copyback = 1;
1900                                         }
1901
1902                                         /* Modulate TS reply iff valid (!0) */
1903                                         memcpy(&tsecr, &opt[6],
1904                                             sizeof(u_int32_t));
1905                                         if (tsecr && dst->scrub &&
1906                                             (dst->scrub->pfss_flags &
1907                                             PFSS_TIMESTAMP)) {
1908                                                 tsecr = ntohl(tsecr)
1909                                                     - dst->scrub->pfss_ts_mod;
1910                                                 pf_change_a(&opt[6],
1911                                                     &th->th_sum, htonl(tsecr),
1912                                                     0);
1913                                                 copyback = 1;
1914                                         }
1915                                         got_ts = 1;
1916                                 }
1917                                 /* FALLTHROUGH */
1918                         default:
1919                                 hlen -= MAX(opt[1], 2);
1920                                 opt += MAX(opt[1], 2);
1921                                 break;
1922                         }
1923                 }
1924                 if (copyback) {
1925                         /* Copyback the options, caller copys back header */
1926                         *writeback = 1;
1927                         m_copyback(m, off + sizeof(struct tcphdr),
1928                             (th->th_off << 2) - sizeof(struct tcphdr), hdr +
1929                             sizeof(struct tcphdr));
1930                 }
1931         }
1932
1933
1934         /*
1935          * Must invalidate PAWS checks on connections idle for too long.
1936          * The fastest allowed timestamp clock is 1ms.  That turns out to
1937          * be about 24 days before it wraps.  XXX Right now our lowerbound
1938          * TS echo check only works for the first 12 days of a connection
1939          * when the TS has exhausted half its 32bit space
1940          */
1941 #define TS_MAX_IDLE     (24*24*60*60)
1942 #define TS_MAX_CONN     (12*24*60*60)   /* XXX remove when better tsecr check */
1943
1944         getmicrouptime(&uptime);
1945         if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) &&
1946             (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE ||
1947             time_uptime - state->creation > TS_MAX_CONN))  {
1948                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1949                         DPFPRINTF(("src idled out of PAWS\n"));
1950                         pf_print_state(state);
1951                         printf("\n");
1952                 }
1953                 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS)
1954                     | PFSS_PAWS_IDLED;
1955         }
1956         if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) &&
1957             uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) {
1958                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1959                         DPFPRINTF(("dst idled out of PAWS\n"));
1960                         pf_print_state(state);
1961                         printf("\n");
1962                 }
1963                 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS)
1964                     | PFSS_PAWS_IDLED;
1965         }
1966
1967         if (got_ts && src->scrub && dst->scrub &&
1968             (src->scrub->pfss_flags & PFSS_PAWS) &&
1969             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1970                 /* Validate that the timestamps are "in-window".
1971                  * RFC1323 describes TCP Timestamp options that allow
1972                  * measurement of RTT (round trip time) and PAWS
1973                  * (protection against wrapped sequence numbers).  PAWS
1974                  * gives us a set of rules for rejecting packets on
1975                  * long fat pipes (packets that were somehow delayed
1976                  * in transit longer than the time it took to send the
1977                  * full TCP sequence space of 4Gb).  We can use these
1978                  * rules and infer a few others that will let us treat
1979                  * the 32bit timestamp and the 32bit echoed timestamp
1980                  * as sequence numbers to prevent a blind attacker from
1981                  * inserting packets into a connection.
1982                  *
1983                  * RFC1323 tells us:
1984                  *  - The timestamp on this packet must be greater than
1985                  *    or equal to the last value echoed by the other
1986                  *    endpoint.  The RFC says those will be discarded
1987                  *    since it is a dup that has already been acked.
1988                  *    This gives us a lowerbound on the timestamp.
1989                  *        timestamp >= other last echoed timestamp
1990                  *  - The timestamp will be less than or equal to
1991                  *    the last timestamp plus the time between the
1992                  *    last packet and now.  The RFC defines the max
1993                  *    clock rate as 1ms.  We will allow clocks to be
1994                  *    up to 10% fast and will allow a total difference
1995                  *    or 30 seconds due to a route change.  And this
1996                  *    gives us an upperbound on the timestamp.
1997                  *        timestamp <= last timestamp + max ticks
1998                  *    We have to be careful here.  Windows will send an
1999                  *    initial timestamp of zero and then initialize it
2000                  *    to a random value after the 3whs; presumably to
2001                  *    avoid a DoS by having to call an expensive RNG
2002                  *    during a SYN flood.  Proof MS has at least one
2003                  *    good security geek.
2004                  *
2005                  *  - The TCP timestamp option must also echo the other
2006                  *    endpoints timestamp.  The timestamp echoed is the
2007                  *    one carried on the earliest unacknowledged segment
2008                  *    on the left edge of the sequence window.  The RFC
2009                  *    states that the host will reject any echoed
2010                  *    timestamps that were larger than any ever sent.
2011                  *    This gives us an upperbound on the TS echo.
2012                  *        tescr <= largest_tsval
2013                  *  - The lowerbound on the TS echo is a little more
2014                  *    tricky to determine.  The other endpoint's echoed
2015                  *    values will not decrease.  But there may be
2016                  *    network conditions that re-order packets and
2017                  *    cause our view of them to decrease.  For now the
2018                  *    only lowerbound we can safely determine is that
2019                  *    the TS echo will never be less than the original
2020                  *    TS.  XXX There is probably a better lowerbound.
2021                  *    Remove TS_MAX_CONN with better lowerbound check.
2022                  *        tescr >= other original TS
2023                  *
2024                  * It is also important to note that the fastest
2025                  * timestamp clock of 1ms will wrap its 32bit space in
2026                  * 24 days.  So we just disable TS checking after 24
2027                  * days of idle time.  We actually must use a 12d
2028                  * connection limit until we can come up with a better
2029                  * lowerbound to the TS echo check.
2030                  */
2031                 struct timeval delta_ts;
2032                 int ts_fudge;
2033
2034
2035                 /*
2036                  * PFTM_TS_DIFF is how many seconds of leeway to allow
2037                  * a host's timestamp.  This can happen if the previous
2038                  * packet got delayed in transit for much longer than
2039                  * this packet.
2040                  */
2041                 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0)
2042                         ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF];
2043
2044                 /* Calculate max ticks since the last timestamp */
2045 #define TS_MAXFREQ      1100            /* RFC max TS freq of 1Khz + 10% skew */
2046 #define TS_MICROSECS    1000000         /* microseconds per second */
2047                 delta_ts = uptime;
2048                 timevalsub(&delta_ts, &src->scrub->pfss_last);
2049                 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ;
2050                 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ);
2051
2052                 if ((src->state >= TCPS_ESTABLISHED &&
2053                     dst->state >= TCPS_ESTABLISHED) &&
2054                     (SEQ_LT(tsval, dst->scrub->pfss_tsecr) ||
2055                     SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) ||
2056                     (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) ||
2057                     SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) {
2058                         /* Bad RFC1323 implementation or an insertion attack.
2059                          *
2060                          * - Solaris 2.6 and 2.7 are known to send another ACK
2061                          *   after the FIN,FIN|ACK,ACK closing that carries
2062                          *   an old timestamp.
2063                          */
2064
2065                         DPFPRINTF(("Timestamp failed %c%c%c%c\n",
2066                             SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ',
2067                             SEQ_GT(tsval, src->scrub->pfss_tsval +
2068                             tsval_from_last) ? '1' : ' ',
2069                             SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ',
2070                             SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' '));
2071                         DPFPRINTF((" tsval: %u  tsecr: %u  +ticks: %u  "
2072                             "idle: %jus %lums\n",
2073                             tsval, tsecr, tsval_from_last,
2074                             (uintmax_t)delta_ts.tv_sec,
2075                             delta_ts.tv_usec / 1000));
2076                         DPFPRINTF((" src->tsval: %u  tsecr: %u\n",
2077                             src->scrub->pfss_tsval, src->scrub->pfss_tsecr));
2078                         DPFPRINTF((" dst->tsval: %u  tsecr: %u  tsval0: %u"
2079                             "\n", dst->scrub->pfss_tsval,
2080                             dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0));
2081                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
2082                                 pf_print_state(state);
2083                                 pf_print_flags(th->th_flags);
2084                                 printf("\n");
2085                         }
2086                         REASON_SET(reason, PFRES_TS);
2087                         return (PF_DROP);
2088                 }
2089
2090                 /* XXX I'd really like to require tsecr but it's optional */
2091
2092         } else if (!got_ts && (th->th_flags & TH_RST) == 0 &&
2093             ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED)
2094             || pd->p_len > 0 || (th->th_flags & TH_SYN)) &&
2095             src->scrub && dst->scrub &&
2096             (src->scrub->pfss_flags & PFSS_PAWS) &&
2097             (dst->scrub->pfss_flags & PFSS_PAWS)) {
2098                 /* Didn't send a timestamp.  Timestamps aren't really useful
2099                  * when:
2100                  *  - connection opening or closing (often not even sent).
2101                  *    but we must not let an attacker to put a FIN on a
2102                  *    data packet to sneak it through our ESTABLISHED check.
2103                  *  - on a TCP reset.  RFC suggests not even looking at TS.
2104                  *  - on an empty ACK.  The TS will not be echoed so it will
2105                  *    probably not help keep the RTT calculation in sync and
2106                  *    there isn't as much danger when the sequence numbers
2107                  *    got wrapped.  So some stacks don't include TS on empty
2108                  *    ACKs :-(
2109                  *
2110                  * To minimize the disruption to mostly RFC1323 conformant
2111                  * stacks, we will only require timestamps on data packets.
2112                  *
2113                  * And what do ya know, we cannot require timestamps on data
2114                  * packets.  There appear to be devices that do legitimate
2115                  * TCP connection hijacking.  There are HTTP devices that allow
2116                  * a 3whs (with timestamps) and then buffer the HTTP request.
2117                  * If the intermediate device has the HTTP response cache, it
2118                  * will spoof the response but not bother timestamping its
2119                  * packets.  So we can look for the presence of a timestamp in
2120                  * the first data packet and if there, require it in all future
2121                  * packets.
2122                  */
2123
2124                 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) {
2125                         /*
2126                          * Hey!  Someone tried to sneak a packet in.  Or the
2127                          * stack changed its RFC1323 behavior?!?!
2128                          */
2129                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
2130                                 DPFPRINTF(("Did not receive expected RFC1323 "
2131                                     "timestamp\n"));
2132                                 pf_print_state(state);
2133                                 pf_print_flags(th->th_flags);
2134                                 printf("\n");
2135                         }
2136                         REASON_SET(reason, PFRES_TS);
2137                         return (PF_DROP);
2138                 }
2139         }
2140
2141
2142         /*
2143          * We will note if a host sends his data packets with or without
2144          * timestamps.  And require all data packets to contain a timestamp
2145          * if the first does.  PAWS implicitly requires that all data packets be
2146          * timestamped.  But I think there are middle-man devices that hijack
2147          * TCP streams immediately after the 3whs and don't timestamp their
2148          * packets (seen in a WWW accelerator or cache).
2149          */
2150         if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags &
2151             (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) {
2152                 if (got_ts)
2153                         src->scrub->pfss_flags |= PFSS_DATA_TS;
2154                 else {
2155                         src->scrub->pfss_flags |= PFSS_DATA_NOTS;
2156                         if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub &&
2157                             (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) {
2158                                 /* Don't warn if other host rejected RFC1323 */
2159                                 DPFPRINTF(("Broken RFC1323 stack did not "
2160                                     "timestamp data packet. Disabled PAWS "
2161                                     "security.\n"));
2162                                 pf_print_state(state);
2163                                 pf_print_flags(th->th_flags);
2164                                 printf("\n");
2165                         }
2166                 }
2167         }
2168
2169
2170         /*
2171          * Update PAWS values
2172          */
2173         if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags &
2174             (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) {
2175                 getmicrouptime(&src->scrub->pfss_last);
2176                 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) ||
2177                     (src->scrub->pfss_flags & PFSS_PAWS) == 0)
2178                         src->scrub->pfss_tsval = tsval;
2179
2180                 if (tsecr) {
2181                         if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) ||
2182                             (src->scrub->pfss_flags & PFSS_PAWS) == 0)
2183                                 src->scrub->pfss_tsecr = tsecr;
2184
2185                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 &&
2186                             (SEQ_LT(tsval, src->scrub->pfss_tsval0) ||
2187                             src->scrub->pfss_tsval0 == 0)) {
2188                                 /* tsval0 MUST be the lowest timestamp */
2189                                 src->scrub->pfss_tsval0 = tsval;
2190                         }
2191
2192                         /* Only fully initialized after a TS gets echoed */
2193                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0)
2194                                 src->scrub->pfss_flags |= PFSS_PAWS;
2195                 }
2196         }
2197
2198         /* I have a dream....  TCP segment reassembly.... */
2199         return (0);
2200 }
2201
2202 static int
2203 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th,
2204     int off, sa_family_t af)
2205 {
2206         u_int16_t       *mss;
2207         int              thoff;
2208         int              opt, cnt, optlen = 0;
2209         int              rewrite = 0;
2210         u_char           opts[TCP_MAXOLEN];
2211         u_char          *optp = opts;
2212
2213         thoff = th->th_off << 2;
2214         cnt = thoff - sizeof(struct tcphdr);
2215
2216         if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt,
2217             NULL, NULL, af))
2218                 return (rewrite);
2219
2220         for (; cnt > 0; cnt -= optlen, optp += optlen) {
2221                 opt = optp[0];
2222                 if (opt == TCPOPT_EOL)
2223                         break;
2224                 if (opt == TCPOPT_NOP)
2225                         optlen = 1;
2226                 else {
2227                         if (cnt < 2)
2228                                 break;
2229                         optlen = optp[1];
2230                         if (optlen < 2 || optlen > cnt)
2231                                 break;
2232                 }
2233                 switch (opt) {
2234                 case TCPOPT_MAXSEG:
2235                         mss = (u_int16_t *)(optp + 2);
2236                         if ((ntohs(*mss)) > r->max_mss) {
2237                                 th->th_sum = pf_cksum_fixup(th->th_sum,
2238                                     *mss, htons(r->max_mss), 0);
2239                                 *mss = htons(r->max_mss);
2240                                 rewrite = 1;
2241                         }
2242                         break;
2243                 default:
2244                         break;
2245                 }
2246         }
2247
2248         if (rewrite)
2249                 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts);
2250
2251         return (rewrite);
2252 }
2253
2254 #ifdef INET
2255 static void
2256 pf_scrub_ip(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos)
2257 {
2258         struct mbuf             *m = *m0;
2259         struct ip               *h = mtod(m, struct ip *);
2260
2261         /* Clear IP_DF if no-df was requested */
2262         if (flags & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
2263                 u_int16_t ip_off = h->ip_off;
2264
2265                 h->ip_off &= htons(~IP_DF);
2266                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
2267         }
2268
2269         /* Enforce a minimum ttl, may cause endless packet loops */
2270         if (min_ttl && h->ip_ttl < min_ttl) {
2271                 u_int16_t ip_ttl = h->ip_ttl;
2272
2273                 h->ip_ttl = min_ttl;
2274                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
2275         }
2276
2277         /* Enforce tos */
2278         if (flags & PFRULE_SET_TOS) {
2279                 u_int16_t       ov, nv;
2280
2281                 ov = *(u_int16_t *)h;
2282                 h->ip_tos = tos;
2283                 nv = *(u_int16_t *)h;
2284
2285                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0);
2286         }
2287
2288         /* random-id, but not for fragments */
2289         if (flags & PFRULE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) {
2290                 u_int16_t ip_id = h->ip_id;
2291
2292                 h->ip_id = ip_randomid();
2293                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0);
2294         }
2295 }
2296 #endif /* INET */
2297
2298 #ifdef INET6
2299 static void
2300 pf_scrub_ip6(struct mbuf **m0, u_int8_t min_ttl)
2301 {
2302         struct mbuf             *m = *m0;
2303         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
2304
2305         /* Enforce a minimum ttl, may cause endless packet loops */
2306         if (min_ttl && h->ip6_hlim < min_ttl)
2307                 h->ip6_hlim = min_ttl;
2308 }
2309 #endif