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/kernel.h>
  38 #include <sys/lock.h>
  39 #include <sys/mbuf.h>
  40 #include <sys/mutex.h>
  41 #include <sys/refcount.h>
  42 #include <sys/rwlock.h>
  43 #include <sys/socket.h>
  44
  45 #include <net/if.h>
  46 #include <net/vnet.h>
  47 #include <net/pfvar.h>
  48 #include <net/if_pflog.h>
  49
  50 #include <netinet/in.h>
  51 #include <netinet/ip.h>
  52 #include <netinet/ip_var.h>
  53 #include <netinet6/ip6_var.h>
  54 #include <netinet/tcp.h>
  55 #include <netinet/tcp_fsm.h>
  56 #include <netinet/tcp_seq.h>
  57
  58 #ifdef INET6
  59 #include <netinet/ip6.h>
  60 #endif /* INET6 */
  61
  62 struct pf_frent {
  63         TAILQ_ENTRY(pf_frent)   fr_next;
  64         struct mbuf     *fe_m;
  65         uint16_t        fe_hdrlen;      /* ipv4 header lenght with ip options
  66                                            ipv6, extension, fragment header */
  67         uint16_t        fe_extoff;      /* last extension header offset or 0 */
  68         uint16_t        fe_len;         /* fragment length */
  69         uint16_t        fe_off;         /* fragment offset */
  70         uint16_t        fe_mff;         /* more fragment flag */
  71 };
  72
  73 struct pf_fragment_cmp {
  74         struct pf_addr  frc_src;
  75         struct pf_addr  frc_dst;
  76         uint32_t        frc_id;
  77         sa_family_t     frc_af;
  78         uint8_t         frc_proto;
  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
  89         RB_ENTRY(pf_fragment) fr_entry;
  90         TAILQ_ENTRY(pf_fragment) frag_next;
  91         uint8_t         fr_flags;       /* status flags */
  92 #define PFFRAG_SEENLAST         0x0001  /* Seen the last fragment for this */
  93 #define PFFRAG_NOBUFFER         0x0002  /* Non-buffering fragment cache */
  94 #define PFFRAG_DROP             0x0004  /* Drop all fragments */
  95 #define BUFFER_FRAGMENTS(fr)    (!((fr)->fr_flags & PFFRAG_NOBUFFER))
  96         uint16_t        fr_max;         /* fragment data max */
  97         uint32_t        fr_timeout;
  98         uint16_t        fr_maxlen;      /* maximum length of single fragment */
  99         TAILQ_HEAD(pf_fragq, pf_frent) fr_queue;
 100 };
 101
 102 struct pf_fragment_tag {
 103         uint16_t        ft_hdrlen;      /* header length of reassembled pkt */
 104         uint16_t        ft_extoff;      /* last extension header offset or 0 */
 105         uint16_t        ft_maxlen;      /* maximum fragment payload length */
 106         uint32_t        ft_id;          /* fragment id */
 107 };
 108
 109 static struct mtx pf_frag_mtx;
 110 MTX_SYSINIT(pf_frag_mtx, &pf_frag_mtx, "pf fragments", MTX_DEF);
 111 #define PF_FRAG_LOCK()          mtx_lock(&pf_frag_mtx)
 112 #define PF_FRAG_UNLOCK()        mtx_unlock(&pf_frag_mtx)
 113 #define PF_FRAG_ASSERT()        mtx_assert(&pf_frag_mtx, MA_OWNED)
 114
 115 VNET_DEFINE(uma_zone_t, pf_state_scrub_z);      /* XXX: shared with pfsync */
 116
 117 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, 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 }
 180 #endif  /* INET */
 181
 182 void
 183 pf_normalize_init(void)
 184 {
 185
 186         V_pf_frag_z = uma_zcreate("pf frags", sizeof(struct pf_fragment),
 187             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 188         V_pf_frent_z = uma_zcreate("pf frag entries", sizeof(struct pf_frent),
 189             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 190         V_pf_state_scrub_z = uma_zcreate("pf state scrubs",
 191             sizeof(struct pf_state_scrub),  NULL, NULL, NULL, NULL,
 192             UMA_ALIGN_PTR, 0);
 193
 194         V_pf_limits[PF_LIMIT_FRAGS].zone = V_pf_frent_z;
 195         V_pf_limits[PF_LIMIT_FRAGS].limit = PFFRAG_FRENT_HIWAT;
 196         uma_zone_set_max(V_pf_frent_z, PFFRAG_FRENT_HIWAT);
 197         uma_zone_set_warning(V_pf_frent_z, "PF frag entries limit reached");
 198
 199         TAILQ_INIT(&V_pf_fragqueue);
 200         TAILQ_INIT(&V_pf_cachequeue);
 201 }
 202
 203 void
 204 pf_normalize_cleanup(void)
 205 {
 206
 207         uma_zdestroy(V_pf_state_scrub_z);
 208         uma_zdestroy(V_pf_frent_z);
 209         uma_zdestroy(V_pf_frag_z);
 210 }
 211
 212 static int
 213 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b)
 214 {
 215         int     diff;
 216
 217         if ((diff = a->fr_id - b->fr_id) != 0)
 218                 return (diff);
 219         if ((diff = a->fr_proto - b->fr_proto) != 0)
 220                 return (diff);
 221         if ((diff = a->fr_af - b->fr_af) != 0)
 222                 return (diff);
 223         if ((diff = pf_addr_cmp(&a->fr_src, &b->fr_src, a->fr_af)) != 0)
 224                 return (diff);
 225         if ((diff = pf_addr_cmp(&a->fr_dst, &b->fr_dst, a->fr_af)) != 0)
 226                 return (diff);
 227         return (0);
 228 }
 229
 230 void
 231 pf_purge_expired_fragments(void)
 232 {
 233         struct pf_fragment      *frag;
 234         u_int32_t                expire = time_uptime -
 235                                     V_pf_default_rule.timeout[PFTM_FRAG];
 236
 237         PF_FRAG_LOCK();
 238         while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) {
 239                 KASSERT((BUFFER_FRAGMENTS(frag)),
 240                     ("BUFFER_FRAGMENTS(frag) == 0: %s", __FUNCTION__));
 241                 if (frag->fr_timeout > expire)
 242                         break;
 243
 244                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 245                 pf_free_fragment(frag);
 246         }
 247
 248         while ((frag = TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue)) != NULL) {
 249                 KASSERT((!BUFFER_FRAGMENTS(frag)),
 250                     ("BUFFER_FRAGMENTS(frag) != 0: %s", __FUNCTION__));
 251                 if (frag->fr_timeout > expire)
 252                         break;
 253
 254                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 255                 pf_free_fragment(frag);
 256                 KASSERT((TAILQ_EMPTY(&V_pf_cachequeue) ||
 257                     TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue) != frag),
 258                     ("!(TAILQ_EMPTY() || TAILQ_LAST() == farg): %s",
 259                     __FUNCTION__));
 260         }
 261         PF_FRAG_UNLOCK();
 262 }
 263
 264 /*
 265  * Try to flush old fragments to make space for new ones
 266  */
 267 static void
 268 pf_flush_fragments(void)
 269 {
 270         struct pf_fragment      *frag, *cache;
 271         int                      goal;
 272
 273         PF_FRAG_ASSERT();
 274
 275         goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10;
 276         DPFPRINTF(("trying to free %d frag entriess\n", goal));
 277         while (goal < uma_zone_get_cur(V_pf_frent_z)) {
 278                 frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue);
 279                 if (frag)
 280                         pf_free_fragment(frag);
 281                 cache = TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue);
 282                 if (cache)
 283                         pf_free_fragment(cache);
 284                 if (frag == NULL && cache == NULL)
 285                         break;
 286         }
 287 }
 288
 289 /* Frees the fragments and all associated entries */
 290 static void
 291 pf_free_fragment(struct pf_fragment *frag)
 292 {
 293         struct pf_frent         *frent;
 294
 295         PF_FRAG_ASSERT();
 296
 297         /* Free all fragments */
 298         if (BUFFER_FRAGMENTS(frag)) {
 299                 for (frent = TAILQ_FIRST(&frag->fr_queue); frent;
 300                     frent = TAILQ_FIRST(&frag->fr_queue)) {
 301                         TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
 302
 303                         m_freem(frent->fe_m);
 304                         uma_zfree(V_pf_frent_z, frent);
 305                 }
 306         } else {
 307                 for (frent = TAILQ_FIRST(&frag->fr_queue); frent;
 308                     frent = TAILQ_FIRST(&frag->fr_queue)) {
 309                         TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
 310
 311                         KASSERT((TAILQ_EMPTY(&frag->fr_queue) ||
 312                             TAILQ_FIRST(&frag->fr_queue)->fe_off >
 313                             frent->fe_len),
 314                             ("! (TAILQ_EMPTY() || TAILQ_FIRST()->fe_off >"
 315                             " frent->fe_len): %s", __func__));
 316
 317                         uma_zfree(V_pf_frent_z, frent);
 318                 }
 319         }
 320
 321         pf_remove_fragment(frag);
 322 }
 323
 324 static struct pf_fragment *
 325 pf_find_fragment(struct pf_fragment_cmp *key, struct pf_frag_tree *tree)
 326 {
 327         struct pf_fragment      *frag;
 328
 329         PF_FRAG_ASSERT();
 330
 331         frag = RB_FIND(pf_frag_tree, tree, (struct pf_fragment *)key);
 332         if (frag != NULL) {
 333                 /* XXX Are we sure we want to update the timeout? */
 334                 frag->fr_timeout = time_uptime;
 335                 if (BUFFER_FRAGMENTS(frag)) {
 336                         TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 337                         TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
 338                 } else {
 339                         TAILQ_REMOVE(&V_pf_cachequeue, frag, frag_next);
 340                         TAILQ_INSERT_HEAD(&V_pf_cachequeue, frag, frag_next);
 341                 }
 342         }
 343
 344         return (frag);
 345 }
 346
 347 /* Removes a fragment from the fragment queue and frees the fragment */
 348 static void
 349 pf_remove_fragment(struct pf_fragment *frag)
 350 {
 351
 352         PF_FRAG_ASSERT();
 353
 354         if (BUFFER_FRAGMENTS(frag)) {
 355                 RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag);
 356                 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 357                 uma_zfree(V_pf_frag_z, frag);
 358         } else {
 359                 RB_REMOVE(pf_frag_tree, &V_pf_cache_tree, frag);
 360                 TAILQ_REMOVE(&V_pf_cachequeue, frag, frag_next);
 361                 uma_zfree(V_pf_frag_z, frag);
 362         }
 363 }
 364
 365 static struct pf_frent *
 366 pf_create_fragment(u_short *reason)
 367 {
 368         struct pf_frent *frent;
 369
 370         PF_FRAG_ASSERT();
 371
 372         frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 373         if (frent == NULL) {
 374                 pf_flush_fragments();
 375                 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 376                 if (frent == NULL) {
 377                         REASON_SET(reason, PFRES_MEMORY);
 378                         return (NULL);
 379                 }
 380         }
 381
 382         return (frent);
 383 }
 384
 385 static struct pf_fragment *
 386 pf_fillup_fragment(struct pf_fragment_cmp *key, struct pf_frent *frent,
 387                 u_short *reason)
 388 {
 389         struct pf_frent         *after, *next, *prev;
 390         struct pf_fragment      *frag;
 391         uint16_t                total;
 392
 393         PF_FRAG_ASSERT();
 394
 395         /* No empty fragments. */
 396         if (frent->fe_len == 0) {
 397                 DPFPRINTF(("bad fragment: len 0"));
 398                 goto bad_fragment;
 399         }
 400
 401         /* All fragments are 8 byte aligned. */
 402         if (frent->fe_mff && (frent->fe_len & 0x7)) {
 403                 DPFPRINTF(("bad fragment: mff and len %d", frent->fe_len));
 404                 goto bad_fragment;
 405         }
 406
 407         /* Respect maximum length, IP_MAXPACKET == IPV6_MAXPACKET. */
 408         if (frent->fe_off + frent->fe_len > IP_MAXPACKET) {
 409                 DPFPRINTF(("bad fragment: max packet %d",
 410                     frent->fe_off + frent->fe_len));
 411                 goto bad_fragment;
 412         }
 413
 414         DPFPRINTF((key->frc_af == AF_INET ?
 415             "reass frag %d @ %d-%d" : "reass frag %#08x @ %d-%d",
 416             key->frc_id, frent->fe_off, frent->fe_off + frent->fe_len));
 417
 418         /* Fully buffer all of the fragments in this fragment queue. */
 419         frag = pf_find_fragment(key, &V_pf_frag_tree);
 420
 421         /* Create a new reassembly queue for this packet. */
 422         if (frag == NULL) {
 423                 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 424                 if (frag == NULL) {
 425                         pf_flush_fragments();
 426                         frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 427                         if (frag == NULL) {
 428                                 REASON_SET(reason, PFRES_MEMORY);
 429                                 goto drop_fragment;
 430                         }
 431                 }
 432
 433                 *(struct pf_fragment_cmp *)frag = *key;
 434                 frag->fr_flags = 0;
 435                 frag->fr_timeout = time_second;
 436                 frag->fr_maxlen = frent->fe_len;
 437                 TAILQ_INIT(&frag->fr_queue);
 438
 439                 RB_INSERT(pf_frag_tree, &V_pf_frag_tree, frag);
 440                 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
 441
 442                 /* We do not have a previous fragment. */
 443                 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next);
 444
 445                 return (frag);
 446         }
 447
 448         KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue"));
 449
 450         /* Remember maximum fragment len for refragmentation. */
 451         if (frent->fe_len > frag->fr_maxlen)
 452                 frag->fr_maxlen = frent->fe_len;
 453
 454         /* Maximum data we have seen already. */
 455         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 456                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 457
 458         /* Non terminal fragments must have more fragments flag. */
 459         if (frent->fe_off + frent->fe_len < total && !frent->fe_mff)
 460                 goto bad_fragment;
 461
 462         /* Check if we saw the last fragment already. */
 463         if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) {
 464                 if (frent->fe_off + frent->fe_len > total ||
 465                     (frent->fe_off + frent->fe_len == total && frent->fe_mff))
 466                         goto bad_fragment;
 467         } else {
 468                 if (frent->fe_off + frent->fe_len == total && !frent->fe_mff)
 469                         goto bad_fragment;
 470         }
 471
 472         /* Find a fragment after the current one. */
 473         prev = NULL;
 474         TAILQ_FOREACH(after, &frag->fr_queue, fr_next) {
 475                 if (after->fe_off > frent->fe_off)
 476                         break;
 477                 prev = after;
 478         }
 479
 480         KASSERT(prev != NULL || after != NULL,
 481             ("prev != NULL || after != NULL"));
 482
 483         if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) {
 484                 uint16_t precut;
 485
 486                 precut = prev->fe_off + prev->fe_len - frent->fe_off;
 487                 if (precut >= frent->fe_len)
 488                         goto bad_fragment;
 489                 DPFPRINTF(("overlap -%d", precut));
 490                 m_adj(frent->fe_m, precut);
 491                 frent->fe_off += precut;
 492                 frent->fe_len -= precut;
 493         }
 494
 495         for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off;
 496             after = next) {
 497                 uint16_t aftercut;
 498
 499                 aftercut = frent->fe_off + frent->fe_len - after->fe_off;
 500                 DPFPRINTF(("adjust overlap %d", aftercut));
 501                 if (aftercut < after->fe_len) {
 502                         m_adj(after->fe_m, aftercut);
 503                         after->fe_off += aftercut;
 504                         after->fe_len -= aftercut;
 505                         break;
 506                 }
 507
 508                 /* This fragment is completely overlapped, lose it. */
 509                 next = TAILQ_NEXT(after, fr_next);
 510                 m_freem(after->fe_m);
 511                 TAILQ_REMOVE(&frag->fr_queue, after, fr_next);
 512                 uma_zfree(V_pf_frent_z, after);
 513         }
 514
 515         if (prev == NULL)
 516                 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next);
 517         else
 518                 TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next);
 519
 520         return (frag);
 521
 522 bad_fragment:
 523         REASON_SET(reason, PFRES_FRAG);
 524 drop_fragment:
 525         uma_zfree(V_pf_frent_z, frent);
 526         return (NULL);
 527 }
 528
 529 static int
 530 pf_isfull_fragment(struct pf_fragment *frag)
 531 {
 532         struct pf_frent *frent, *next;
 533         uint16_t off, total;
 534
 535         /* Check if we are completely reassembled */
 536         if (TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff)
 537                 return (0);
 538
 539         /* Maximum data we have seen already */
 540         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 541                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 542
 543         /* Check if we have all the data */
 544         off = 0;
 545         for (frent = TAILQ_FIRST(&frag->fr_queue); frent; frent = next) {
 546                 next = TAILQ_NEXT(frent, fr_next);
 547
 548                 off += frent->fe_len;
 549                 if (off < total && (next == NULL || next->fe_off != off)) {
 550                         DPFPRINTF(("missing fragment at %d, next %d, total %d",
 551                             off, next == NULL ? -1 : next->fe_off, total));
 552                         return (0);
 553                 }
 554         }
 555         DPFPRINTF(("%d < %d?", off, total));
 556         if (off < total)
 557                 return (0);
 558         KASSERT(off == total, ("off == total"));
 559
 560         return (1);
 561 }
 562
 563 static struct mbuf *
 564 pf_join_fragment(struct pf_fragment *frag)
 565 {
 566         struct mbuf *m, *m2;
 567         struct pf_frent *frent, *next;
 568
 569         frent = TAILQ_FIRST(&frag->fr_queue);
 570         next = TAILQ_NEXT(frent, fr_next);
 571
 572         m = frent->fe_m;
 573         m_adj(m, (frent->fe_hdrlen + frent->fe_len) - m->m_pkthdr.len);
 574         uma_zfree(V_pf_frent_z, frent);
 575         for (frent = next; frent != NULL; frent = next) {
 576                 next = TAILQ_NEXT(frent, fr_next);
 577
 578                 m2 = frent->fe_m;
 579                 /* Strip off ip header. */
 580                 m_adj(m2, frent->fe_hdrlen);
 581                 /* Strip off any trailing bytes. */
 582                 m_adj(m2, frent->fe_len - m2->m_pkthdr.len);
 583
 584                 uma_zfree(V_pf_frent_z, frent);
 585                 m_cat(m, m2);
 586         }
 587
 588         /* Remove from fragment queue. */
 589         pf_remove_fragment(frag);
 590
 591         return (m);
 592 }
 593
 594 #ifdef INET
 595 static int
 596 pf_reassemble(struct mbuf **m0, struct ip *ip, int dir, u_short *reason)
 597 {
 598         struct mbuf             *m = *m0;
 599         struct pf_frent         *frent;
 600         struct pf_fragment      *frag;
 601         struct pf_fragment_cmp  key;
 602         uint16_t                total, hdrlen;
 603
 604         /* Get an entry for the fragment queue */
 605         if ((frent = pf_create_fragment(reason)) == NULL)
 606                 return (PF_DROP);
 607
 608         frent->fe_m = m;
 609         frent->fe_hdrlen = ip->ip_hl << 2;
 610         frent->fe_extoff = 0;
 611         frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2);
 612         frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3;
 613         frent->fe_mff = ntohs(ip->ip_off) & IP_MF;
 614
 615         pf_ip2key(ip, dir, &key);
 616
 617         if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL)
 618                 return (PF_DROP);
 619
 620         /* The mbuf is part of the fragment entry, no direct free or access */
 621         m = *m0 = NULL;
 622
 623         if (!pf_isfull_fragment(frag))
 624                 return (PF_PASS);  /* drop because *m0 is NULL, no error */
 625
 626         /* We have all the data */
 627         frent = TAILQ_FIRST(&frag->fr_queue);
 628         KASSERT(frent != NULL, ("frent != NULL"));
 629         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 630                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 631         hdrlen = frent->fe_hdrlen;
 632
 633         m = *m0 = pf_join_fragment(frag);
 634         frag = NULL;
 635
 636         if (m->m_flags & M_PKTHDR) {
 637                 int plen = 0;
 638                 for (m = *m0; m; m = m->m_next)
 639                         plen += m->m_len;
 640                 m = *m0;
 641                 m->m_pkthdr.len = plen;
 642         }
 643
 644         ip = mtod(m, struct ip *);
 645         ip->ip_len = htons(hdrlen + total);
 646         ip->ip_off &= ~(IP_MF|IP_OFFMASK);
 647
 648         if (hdrlen + total > IP_MAXPACKET) {
 649                 DPFPRINTF(("drop: too big: %d", total));
 650                 ip->ip_len = 0;
 651                 REASON_SET(reason, PFRES_SHORT);
 652                 /* PF_DROP requires a valid mbuf *m0 in pf_test() */
 653                 return (PF_DROP);
 654         }
 655
 656         DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len)));
 657         return (PF_PASS);
 658 }
 659 #endif  /* INET */
 660
 661 #ifdef INET6
 662 static int
 663 pf_reassemble6(struct mbuf **m0, struct ip6_hdr *ip6, struct ip6_frag *fraghdr,
 664     uint16_t hdrlen, uint16_t extoff, u_short *reason)
 665 {
 666         struct mbuf             *m = *m0;
 667         struct pf_frent         *frent;
 668         struct pf_fragment      *frag;
 669         struct pf_fragment_cmp   key;
 670         struct m_tag            *mtag;
 671         struct pf_fragment_tag  *ftag;
 672         int                      off;
 673         uint32_t                 frag_id;
 674         uint16_t                 total, maxlen;
 675         uint8_t                  proto;
 676
 677         PF_FRAG_LOCK();
 678
 679         /* Get an entry for the fragment queue. */
 680         if ((frent = pf_create_fragment(reason)) == NULL) {
 681                 PF_FRAG_UNLOCK();
 682                 return (PF_DROP);
 683         }
 684
 685         frent->fe_m = m;
 686         frent->fe_hdrlen = hdrlen;
 687         frent->fe_extoff = extoff;
 688         frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen;
 689         frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK);
 690         frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG;
 691
 692         key.frc_src.v6 = ip6->ip6_src;
 693         key.frc_dst.v6 = ip6->ip6_dst;
 694         key.frc_af = AF_INET6;
 695         /* Only the first fragment's protocol is relevant. */
 696         key.frc_proto = 0;
 697         key.frc_id = fraghdr->ip6f_ident;
 698
 699         if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) {
 700                 PF_FRAG_UNLOCK();
 701                 return (PF_DROP);
 702         }
 703
 704         /* The mbuf is part of the fragment entry, no direct free or access. */
 705         m = *m0 = NULL;
 706
 707         if (!pf_isfull_fragment(frag)) {
 708                 PF_FRAG_UNLOCK();
 709                 return (PF_PASS);  /* Drop because *m0 is NULL, no error. */
 710         }
 711
 712         /* We have all the data. */
 713         extoff = frent->fe_extoff;
 714         maxlen = frag->fr_maxlen;
 715         frag_id = frag->fr_id;
 716         frent = TAILQ_FIRST(&frag->fr_queue);
 717         KASSERT(frent != NULL, ("frent != NULL"));
 718         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 719                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 720         hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag);
 721
 722         m = *m0 = pf_join_fragment(frag);
 723         frag = NULL;
 724
 725         PF_FRAG_UNLOCK();
 726
 727         /* Take protocol from first fragment header. */
 728         m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off);
 729         KASSERT(m, ("%s: short mbuf chain", __func__));
 730         proto = *(mtod(m, caddr_t) + off);
 731         m = *m0;
 732
 733         /* Delete frag6 header */
 734         if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0)
 735                 goto fail;
 736
 737         if (m->m_flags & M_PKTHDR) {
 738                 int plen = 0;
 739                 for (m = *m0; m; m = m->m_next)
 740                         plen += m->m_len;
 741                 m = *m0;
 742                 m->m_pkthdr.len = plen;
 743         }
 744
 745         if ((mtag = m_tag_get(PF_REASSEMBLED, sizeof(struct pf_fragment_tag),
 746             M_NOWAIT)) == NULL)
 747                 goto fail;
 748         ftag = (struct pf_fragment_tag *)(mtag + 1);
 749         ftag->ft_hdrlen = hdrlen;
 750         ftag->ft_extoff = extoff;
 751         ftag->ft_maxlen = maxlen;
 752         ftag->ft_id = frag_id;
 753         m_tag_prepend(m, mtag);
 754
 755         ip6 = mtod(m, struct ip6_hdr *);
 756         ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total);
 757         if (extoff) {
 758                 /* Write protocol into next field of last extension header. */
 759                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
 760                     &off);
 761                 KASSERT(m, ("%s: short mbuf chain", __func__));
 762                 *(mtod(m, char *) + off) = proto;
 763                 m = *m0;
 764         } else
 765                 ip6->ip6_nxt = proto;
 766
 767         if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) {
 768                 DPFPRINTF(("drop: too big: %d", total));
 769                 ip6->ip6_plen = 0;
 770                 REASON_SET(reason, PFRES_SHORT);
 771                 /* PF_DROP requires a valid mbuf *m0 in pf_test6(). */
 772                 return (PF_DROP);
 773         }
 774
 775         DPFPRINTF(("complete: %p(%d)", m, ntohs(ip6->ip6_plen)));
 776         return (PF_PASS);
 777
 778 fail:
 779         REASON_SET(reason, PFRES_MEMORY);
 780         /* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */
 781         return (PF_DROP);
 782 }
 783 #endif  /* INET6 */
 784
 785 #ifdef INET
 786 static struct mbuf *
 787 pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff,
 788     int drop, int *nomem)
 789 {
 790         struct mbuf             *m = *m0;
 791         struct pf_frent         *frp, *fra, *cur = NULL;
 792         int                      ip_len = ntohs(h->ip_len) - (h->ip_hl << 2);
 793         u_int16_t                off = ntohs(h->ip_off) << 3;
 794         u_int16_t                max = ip_len + off;
 795         int                      hosed = 0;
 796
 797         PF_FRAG_ASSERT();
 798         KASSERT((*frag == NULL || !BUFFER_FRAGMENTS(*frag)),
 799             ("!(*frag == NULL || !BUFFER_FRAGMENTS(*frag)): %s", __FUNCTION__));
 800
 801         /* Create a new range queue for this packet */
 802         if (*frag == NULL) {
 803                 *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 804                 if (*frag == NULL) {
 805                         pf_flush_fragments();
 806                         *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 807                         if (*frag == NULL)
 808                                 goto no_mem;
 809                 }
 810
 811                 /* Get an entry for the queue */
 812                 cur = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 813                 if (cur == NULL) {
 814                         uma_zfree(V_pf_frag_z, *frag);
 815                         *frag = NULL;
 816                         goto no_mem;
 817                 }
 818
 819                 (*frag)->fr_flags = PFFRAG_NOBUFFER;
 820                 (*frag)->fr_max = 0;
 821                 (*frag)->fr_src.v4 = h->ip_src;
 822                 (*frag)->fr_dst.v4 = h->ip_dst;
 823                 (*frag)->fr_af = AF_INET;
 824                 (*frag)->fr_proto = h->ip_p;
 825                 (*frag)->fr_id = h->ip_id;
 826                 (*frag)->fr_timeout = time_uptime;
 827
 828                 cur->fe_off = off;
 829                 cur->fe_len = max; /* TODO: fe_len = max - off ? */
 830                 TAILQ_INIT(&(*frag)->fr_queue);
 831                 TAILQ_INSERT_HEAD(&(*frag)->fr_queue, cur, fr_next);
 832
 833                 RB_INSERT(pf_frag_tree, &V_pf_cache_tree, *frag);
 834                 TAILQ_INSERT_HEAD(&V_pf_cachequeue, *frag, frag_next);
 835
 836                 DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max));
 837
 838                 goto pass;
 839         }
 840
 841         /*
 842          * Find a fragment after the current one:
 843          *  - off contains the real shifted offset.
 844          */
 845         frp = NULL;
 846         TAILQ_FOREACH(fra, &(*frag)->fr_queue, fr_next) {
 847                 if (fra->fe_off > off)
 848                         break;
 849                 frp = fra;
 850         }
 851
 852         KASSERT((frp != NULL || fra != NULL),
 853             ("!(frp != NULL || fra != NULL): %s", __FUNCTION__));
 854
 855         if (frp != NULL) {
 856                 int     precut;
 857
 858                 precut = frp->fe_len - off;
 859                 if (precut >= ip_len) {
 860                         /* Fragment is entirely a duplicate */
 861                         DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n",
 862                             h->ip_id, frp->fe_off, frp->fe_len, off, max));
 863                         goto drop_fragment;
 864                 }
 865                 if (precut == 0) {
 866                         /* They are adjacent.  Fixup cache entry */
 867                         DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n",
 868                             h->ip_id, frp->fe_off, frp->fe_len, off, max));
 869                         frp->fe_len = max;
 870                 } else if (precut > 0) {
 871                         /* The first part of this payload overlaps with a
 872                          * fragment that has already been passed.
 873                          * Need to trim off the first part of the payload.
 874                          * But to do so easily, we need to create another
 875                          * mbuf to throw the original header into.
 876                          */
 877
 878                         DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n",
 879                             h->ip_id, precut, frp->fe_off, frp->fe_len, off,
 880                             max));
 881
 882                         off += precut;
 883                         max -= precut;
 884                         /* Update the previous frag to encompass this one */
 885                         frp->fe_len = max;
 886
 887                         if (!drop) {
 888                                 /* XXX Optimization opportunity
 889                                  * This is a very heavy way to trim the payload.
 890                                  * we could do it much faster by diddling mbuf
 891                                  * internals but that would be even less legible
 892                                  * than this mbuf magic.  For my next trick,
 893                                  * I'll pull a rabbit out of my laptop.
 894                                  */
 895                                 *m0 = m_dup(m, M_NOWAIT);
 896                                 if (*m0 == NULL)
 897                                         goto no_mem;
 898                                 /* From KAME Project : We have missed this! */
 899                                 m_adj(*m0, (h->ip_hl << 2) -
 900                                     (*m0)->m_pkthdr.len);
 901
 902                                 KASSERT(((*m0)->m_next == NULL),
 903                                     ("(*m0)->m_next != NULL: %s",
 904                                     __FUNCTION__));
 905                                 m_adj(m, precut + (h->ip_hl << 2));
 906                                 m_cat(*m0, m);
 907                                 m = *m0;
 908                                 if (m->m_flags & M_PKTHDR) {
 909                                         int plen = 0;
 910                                         struct mbuf *t;
 911                                         for (t = m; t; t = t->m_next)
 912                                                 plen += t->m_len;
 913                                         m->m_pkthdr.len = plen;
 914                                 }
 915
 916
 917                                 h = mtod(m, struct ip *);
 918
 919                                 KASSERT(((int)m->m_len ==
 920                                     ntohs(h->ip_len) - precut),
 921                                     ("m->m_len != ntohs(h->ip_len) - precut: %s",
 922                                     __FUNCTION__));
 923                                 h->ip_off = htons(ntohs(h->ip_off) +
 924                                     (precut >> 3));
 925                                 h->ip_len = htons(ntohs(h->ip_len) - precut);
 926                         } else {
 927                                 hosed++;
 928                         }
 929                 } else {
 930                         /* There is a gap between fragments */
 931
 932                         DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n",
 933                             h->ip_id, -precut, frp->fe_off, frp->fe_len, off,
 934                             max));
 935
 936                         cur = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 937                         if (cur == NULL)
 938                                 goto no_mem;
 939
 940                         cur->fe_off = off;
 941                         cur->fe_len = max;
 942                         TAILQ_INSERT_AFTER(&(*frag)->fr_queue, frp, cur, fr_next);
 943                 }
 944         }
 945
 946         if (fra != NULL) {
 947                 int     aftercut;
 948                 int     merge = 0;
 949
 950                 aftercut = max - fra->fe_off;
 951                 if (aftercut == 0) {
 952                         /* Adjacent fragments */
 953                         DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n",
 954                             h->ip_id, off, max, fra->fe_off, fra->fe_len));
 955                         fra->fe_off = off;
 956                         merge = 1;
 957                 } else if (aftercut > 0) {
 958                         /* Need to chop off the tail of this fragment */
 959                         DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n",
 960                             h->ip_id, aftercut, off, max, fra->fe_off,
 961                             fra->fe_len));
 962                         fra->fe_off = off;
 963                         max -= aftercut;
 964
 965                         merge = 1;
 966
 967                         if (!drop) {
 968                                 m_adj(m, -aftercut);
 969                                 if (m->m_flags & M_PKTHDR) {
 970                                         int plen = 0;
 971                                         struct mbuf *t;
 972                                         for (t = m; t; t = t->m_next)
 973                                                 plen += t->m_len;
 974                                         m->m_pkthdr.len = plen;
 975                                 }
 976                                 h = mtod(m, struct ip *);
 977                                 KASSERT(((int)m->m_len == ntohs(h->ip_len) - aftercut),
 978                                     ("m->m_len != ntohs(h->ip_len) - aftercut: %s",
 979                                     __FUNCTION__));
 980                                 h->ip_len = htons(ntohs(h->ip_len) - aftercut);
 981                         } else {
 982                                 hosed++;
 983                         }
 984                 } else if (frp == NULL) {
 985                         /* There is a gap between fragments */
 986                         DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n",
 987                             h->ip_id, -aftercut, off, max, fra->fe_off,
 988                             fra->fe_len));
 989
 990                         cur = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 991                         if (cur == NULL)
 992                                 goto no_mem;
 993
 994                         cur->fe_off = off;
 995                         cur->fe_len = max;
 996                         TAILQ_INSERT_HEAD(&(*frag)->fr_queue, cur, fr_next);
 997                 }
 998
 999
1000                 /* Need to glue together two separate fragment descriptors */
1001                 if (merge) {
1002                         if (cur && fra->fe_off <= cur->fe_len) {
1003                                 /* Need to merge in a previous 'cur' */
1004                                 DPFPRINTF(("fragcache[%d]: adjacent(merge "
1005                                     "%d-%d) %d-%d (%d-%d)\n",
1006                                     h->ip_id, cur->fe_off, cur->fe_len, off,
1007                                     max, fra->fe_off, fra->fe_len));
1008                                 fra->fe_off = cur->fe_off;
1009                                 TAILQ_REMOVE(&(*frag)->fr_queue, cur, fr_next);
1010                                 uma_zfree(V_pf_frent_z, cur);
1011                                 cur = NULL;
1012
1013                         } else if (frp && fra->fe_off <= frp->fe_len) {
1014                                 /* Need to merge in a modified 'frp' */
1015                                 KASSERT((cur == NULL), ("cur != NULL: %s",
1016                                     __FUNCTION__));
1017                                 DPFPRINTF(("fragcache[%d]: adjacent(merge "
1018                                     "%d-%d) %d-%d (%d-%d)\n",
1019                                     h->ip_id, frp->fe_off, frp->fe_len, off,
1020                                     max, fra->fe_off, fra->fe_len));
1021                                 fra->fe_off = frp->fe_off;
1022                                 TAILQ_REMOVE(&(*frag)->fr_queue, frp, fr_next);
1023                                 uma_zfree(V_pf_frent_z, frp);
1024                                 frp = NULL;
1025
1026                         }
1027                 }
1028         }
1029
1030         if (hosed) {
1031                 /*
1032                  * We must keep tracking the overall fragment even when
1033                  * we're going to drop it anyway so that we know when to
1034                  * free the overall descriptor.  Thus we drop the frag late.
1035                  */
1036                 goto drop_fragment;
1037         }
1038
1039
1040  pass:
1041         /* Update maximum data size */
1042         if ((*frag)->fr_max < max)
1043                 (*frag)->fr_max = max;
1044
1045         /* This is the last segment */
1046         if (!mff)
1047                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
1048
1049         /* Check if we are completely reassembled */
1050         if (((*frag)->fr_flags & PFFRAG_SEENLAST) &&
1051             TAILQ_FIRST(&(*frag)->fr_queue)->fe_off == 0 &&
1052             TAILQ_FIRST(&(*frag)->fr_queue)->fe_len == (*frag)->fr_max) {
1053                 /* Remove from fragment queue */
1054                 DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id,
1055                     (*frag)->fr_max));
1056                 pf_free_fragment(*frag);
1057                 *frag = NULL;
1058         }
1059
1060         return (m);
1061
1062  no_mem:
1063         *nomem = 1;
1064
1065         /* Still need to pay attention to !IP_MF */
1066         if (!mff && *frag != NULL)
1067                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
1068
1069         m_freem(m);
1070         return (NULL);
1071
1072  drop_fragment:
1073
1074         /* Still need to pay attention to !IP_MF */
1075         if (!mff && *frag != NULL)
1076                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
1077
1078         if (drop) {
1079                 /* This fragment has been deemed bad.  Don't reass */
1080                 if (((*frag)->fr_flags & PFFRAG_DROP) == 0)
1081                         DPFPRINTF(("fragcache[%d]: dropping overall fragment\n",
1082                             h->ip_id));
1083                 (*frag)->fr_flags |= PFFRAG_DROP;
1084         }
1085
1086         m_freem(m);
1087         return (NULL);
1088 }
1089 #endif  /* INET */
1090
1091 #ifdef INET6
1092 int
1093 pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag)
1094 {
1095         struct mbuf             *m = *m0, *t;
1096         struct pf_fragment_tag  *ftag = (struct pf_fragment_tag *)(mtag + 1);
1097         struct pf_pdesc          pd;
1098         uint32_t                 frag_id;
1099         uint16_t                 hdrlen, extoff, maxlen;
1100         uint8_t                  proto;
1101         int                      error, action;
1102
1103         hdrlen = ftag->ft_hdrlen;
1104         extoff = ftag->ft_extoff;
1105         maxlen = ftag->ft_maxlen;
1106         frag_id = ftag->ft_id;
1107         m_tag_delete(m, mtag);
1108         mtag = NULL;
1109         ftag = NULL;
1110
1111         if (extoff) {
1112                 int off;
1113
1114                 /* Use protocol from next field of last extension header */
1115                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
1116                     &off);
1117                 KASSERT((m != NULL), ("pf_refragment6: short mbuf chain"));
1118                 proto = *(mtod(m, caddr_t) + off);
1119                 *(mtod(m, char *) + off) = IPPROTO_FRAGMENT;
1120                 m = *m0;
1121         } else {
1122                 struct ip6_hdr *hdr;
1123
1124                 hdr = mtod(m, struct ip6_hdr *);
1125                 proto = hdr->ip6_nxt;
1126                 hdr->ip6_nxt = IPPROTO_FRAGMENT;
1127         }
1128
1129         /*
1130          * Maxlen may be less than 8 if there was only a single
1131          * fragment.  As it was fragmented before, add a fragment
1132          * header also for a single fragment.  If total or maxlen
1133          * is less than 8, ip6_fragment() will return EMSGSIZE and
1134          * we drop the packet.
1135          */
1136         error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id);
1137         m = (*m0)->m_nextpkt;
1138         (*m0)->m_nextpkt = NULL;
1139         if (error == 0) {
1140                 /* The first mbuf contains the unfragmented packet. */
1141                 m_freem(*m0);
1142                 *m0 = NULL;
1143                 action = PF_PASS;
1144         } else {
1145                 /* Drop expects an mbuf to free. */
1146                 DPFPRINTF(("refragment error %d", error));
1147                 action = PF_DROP;
1148         }
1149         for (t = m; m; m = t) {
1150                 t = m->m_nextpkt;
1151                 m->m_nextpkt = NULL;
1152                 m->m_flags |= M_SKIP_FIREWALL;
1153                 memset(&pd, 0, sizeof(pd));
1154                 pd.pf_mtag = pf_find_mtag(m);
1155                 if (error == 0)
1156                         ip6_forward(m, 0);
1157                 else
1158                         m_freem(m);
1159         }
1160
1161         return (action);
1162 }
1163 #endif /* INET6 */
1164
1165 #ifdef INET
1166 int
1167 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason,
1168     struct pf_pdesc *pd)
1169 {
1170         struct mbuf             *m = *m0;
1171         struct pf_rule          *r;
1172         struct pf_fragment      *frag = NULL;
1173         struct pf_fragment_cmp  key;
1174         struct ip               *h = mtod(m, struct ip *);
1175         int                      mff = (ntohs(h->ip_off) & IP_MF);
1176         int                      hlen = h->ip_hl << 2;
1177         u_int16_t                fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
1178         u_int16_t                max;
1179         int                      ip_len;
1180         int                      ip_off;
1181         int                      tag = -1;
1182         int                      verdict;
1183
1184         PF_RULES_RASSERT();
1185
1186         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1187         while (r != NULL) {
1188                 r->evaluations++;
1189                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1190                         r = r->skip[PF_SKIP_IFP].ptr;
1191                 else if (r->direction && r->direction != dir)
1192                         r = r->skip[PF_SKIP_DIR].ptr;
1193                 else if (r->af && r->af != AF_INET)
1194                         r = r->skip[PF_SKIP_AF].ptr;
1195                 else if (r->proto && r->proto != h->ip_p)
1196                         r = r->skip[PF_SKIP_PROTO].ptr;
1197                 else if (PF_MISMATCHAW(&r->src.addr,
1198                     (struct pf_addr *)&h->ip_src.s_addr, AF_INET,
1199                     r->src.neg, kif, M_GETFIB(m)))
1200                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1201                 else if (PF_MISMATCHAW(&r->dst.addr,
1202                     (struct pf_addr *)&h->ip_dst.s_addr, AF_INET,
1203                     r->dst.neg, NULL, M_GETFIB(m)))
1204                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1205                 else if (r->match_tag && !pf_match_tag(m, r, &tag,
1206                     pd->pf_mtag ? pd->pf_mtag->tag : 0))
1207                         r = TAILQ_NEXT(r, entries);
1208                 else
1209                         break;
1210         }
1211
1212         if (r == NULL || r->action == PF_NOSCRUB)
1213                 return (PF_PASS);
1214         else {
1215                 r->packets[dir == PF_OUT]++;
1216                 r->bytes[dir == PF_OUT] += pd->tot_len;
1217         }
1218
1219         /* Check for illegal packets */
1220         if (hlen < (int)sizeof(struct ip))
1221                 goto drop;
1222
1223         if (hlen > ntohs(h->ip_len))
1224                 goto drop;
1225
1226         /* Clear IP_DF if the rule uses the no-df option */
1227         if (r->rule_flag & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
1228                 u_int16_t ip_off = h->ip_off;
1229
1230                 h->ip_off &= htons(~IP_DF);
1231                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1232         }
1233
1234         /* We will need other tests here */
1235         if (!fragoff && !mff)
1236                 goto no_fragment;
1237
1238         /* We're dealing with a fragment now. Don't allow fragments
1239          * with IP_DF to enter the cache. If the flag was cleared by
1240          * no-df above, fine. Otherwise drop it.
1241          */
1242         if (h->ip_off & htons(IP_DF)) {
1243                 DPFPRINTF(("IP_DF\n"));
1244                 goto bad;
1245         }
1246
1247         ip_len = ntohs(h->ip_len) - hlen;
1248         ip_off = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
1249
1250         /* All fragments are 8 byte aligned */
1251         if (mff && (ip_len & 0x7)) {
1252                 DPFPRINTF(("mff and %d\n", ip_len));
1253                 goto bad;
1254         }
1255
1256         /* Respect maximum length */
1257         if (fragoff + ip_len > IP_MAXPACKET) {
1258                 DPFPRINTF(("max packet %d\n", fragoff + ip_len));
1259                 goto bad;
1260         }
1261         max = fragoff + ip_len;
1262
1263         if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) {
1264
1265                 /* Fully buffer all of the fragments */
1266                 PF_FRAG_LOCK();
1267
1268                 pf_ip2key(h, dir, &key);
1269                 frag = pf_find_fragment(&key, &V_pf_frag_tree);
1270
1271                 /* Check if we saw the last fragment already */
1272                 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
1273                     max > frag->fr_max)
1274                         goto bad;
1275
1276                 /* Might return a completely reassembled mbuf, or NULL */
1277                 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
1278                 verdict = pf_reassemble(m0, h, dir, reason);
1279                 PF_FRAG_UNLOCK();
1280
1281                 if (verdict != PF_PASS)
1282                         return (PF_DROP);
1283
1284                 m = *m0;
1285                 if (m == NULL)
1286                         return (PF_DROP);
1287
1288                 h = mtod(m, struct ip *);
1289         } else {
1290                 /* non-buffering fragment cache (drops or masks overlaps) */
1291                 int     nomem = 0;
1292
1293                 if (dir == PF_OUT && pd->pf_mtag &&
1294                     pd->pf_mtag->flags & PF_TAG_FRAGCACHE) {
1295                         /*
1296                          * Already passed the fragment cache in the
1297                          * input direction.  If we continued, it would
1298                          * appear to be a dup and would be dropped.
1299                          */
1300                         goto fragment_pass;
1301                 }
1302
1303                 PF_FRAG_LOCK();
1304                 pf_ip2key(h, dir, &key);
1305                 frag = pf_find_fragment(&key, &V_pf_cache_tree);
1306
1307                 /* Check if we saw the last fragment already */
1308                 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
1309                     max > frag->fr_max) {
1310                         if (r->rule_flag & PFRULE_FRAGDROP)
1311                                 frag->fr_flags |= PFFRAG_DROP;
1312                         goto bad;
1313                 }
1314
1315                 *m0 = m = pf_fragcache(m0, h, &frag, mff,
1316                     (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem);
1317                 PF_FRAG_UNLOCK();
1318                 if (m == NULL) {
1319                         if (nomem)
1320                                 goto no_mem;
1321                         goto drop;
1322                 }
1323
1324                 if (dir == PF_IN) {
1325                         /* Use mtag from copied and trimmed mbuf chain. */
1326                         pd->pf_mtag = pf_get_mtag(m);
1327                         if (pd->pf_mtag == NULL) {
1328                                 m_freem(m);
1329                                 *m0 = NULL;
1330                                 goto no_mem;
1331                         }
1332                         pd->pf_mtag->flags |= PF_TAG_FRAGCACHE;
1333                 }
1334
1335                 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
1336                         goto drop;
1337                 goto fragment_pass;
1338         }
1339
1340  no_fragment:
1341         /* At this point, only IP_DF is allowed in ip_off */
1342         if (h->ip_off & ~htons(IP_DF)) {
1343                 u_int16_t ip_off = h->ip_off;
1344
1345                 h->ip_off &= htons(IP_DF);
1346                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1347         }
1348
1349         /* not missing a return here */
1350
1351  fragment_pass:
1352         pf_scrub_ip(&m, r->rule_flag, r->min_ttl, r->set_tos);
1353
1354         if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0)
1355                 pd->flags |= PFDESC_IP_REAS;
1356         return (PF_PASS);
1357
1358  no_mem:
1359         REASON_SET(reason, PFRES_MEMORY);
1360         if (r != NULL && r->log)
1361                 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
1362                     1);
1363         return (PF_DROP);
1364
1365  drop:
1366         REASON_SET(reason, PFRES_NORM);
1367         if (r != NULL && r->log)
1368                 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
1369                     1);
1370         return (PF_DROP);
1371
1372  bad:
1373         DPFPRINTF(("dropping bad fragment\n"));
1374
1375         /* Free associated fragments */
1376         if (frag != NULL) {
1377                 pf_free_fragment(frag);
1378                 PF_FRAG_UNLOCK();
1379         }
1380
1381         REASON_SET(reason, PFRES_FRAG);
1382         if (r != NULL && r->log)
1383                 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
1384                     1);
1385
1386         return (PF_DROP);
1387 }
1388 #endif
1389
1390 #ifdef INET6
1391 int
1392 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif,
1393     u_short *reason, struct pf_pdesc *pd)
1394 {
1395         struct mbuf             *m = *m0;
1396         struct pf_rule          *r;
1397         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
1398         int                      extoff;
1399         int                      off;
1400         struct ip6_ext           ext;
1401         struct ip6_opt           opt;
1402         struct ip6_opt_jumbo     jumbo;
1403         struct ip6_frag          frag;
1404         u_int32_t                jumbolen = 0, plen;
1405         int                      optend;
1406         int                      ooff;
1407         u_int8_t                 proto;
1408         int                      terminal;
1409
1410         PF_RULES_RASSERT();
1411
1412         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1413         while (r != NULL) {
1414                 r->evaluations++;
1415                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1416                         r = r->skip[PF_SKIP_IFP].ptr;
1417                 else if (r->direction && r->direction != dir)
1418                         r = r->skip[PF_SKIP_DIR].ptr;
1419                 else if (r->af && r->af != AF_INET6)
1420                         r = r->skip[PF_SKIP_AF].ptr;
1421 #if 0 /* header chain! */
1422                 else if (r->proto && r->proto != h->ip6_nxt)
1423                         r = r->skip[PF_SKIP_PROTO].ptr;
1424 #endif
1425                 else if (PF_MISMATCHAW(&r->src.addr,
1426                     (struct pf_addr *)&h->ip6_src, AF_INET6,
1427                     r->src.neg, kif, M_GETFIB(m)))
1428                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1429                 else if (PF_MISMATCHAW(&r->dst.addr,
1430                     (struct pf_addr *)&h->ip6_dst, AF_INET6,
1431                     r->dst.neg, NULL, M_GETFIB(m)))
1432                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1433                 else
1434                         break;
1435         }
1436
1437         if (r == NULL || r->action == PF_NOSCRUB)
1438                 return (PF_PASS);
1439         else {
1440                 r->packets[dir == PF_OUT]++;
1441                 r->bytes[dir == PF_OUT] += pd->tot_len;
1442         }
1443
1444         /* Check for illegal packets */
1445         if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len)
1446                 goto drop;
1447
1448         extoff = 0;
1449         off = sizeof(struct ip6_hdr);
1450         proto = h->ip6_nxt;
1451         terminal = 0;
1452         do {
1453                 switch (proto) {
1454                 case IPPROTO_FRAGMENT:
1455                         goto fragment;
1456                         break;
1457                 case IPPROTO_AH:
1458                 case IPPROTO_ROUTING:
1459                 case IPPROTO_DSTOPTS:
1460                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1461                             NULL, AF_INET6))
1462                                 goto shortpkt;
1463                         extoff = off;
1464                         if (proto == IPPROTO_AH)
1465                                 off += (ext.ip6e_len + 2) * 4;
1466                         else
1467                                 off += (ext.ip6e_len + 1) * 8;
1468                         proto = ext.ip6e_nxt;
1469                         break;
1470                 case IPPROTO_HOPOPTS:
1471                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1472                             NULL, AF_INET6))
1473                                 goto shortpkt;
1474                         extoff = off;
1475                         optend = off + (ext.ip6e_len + 1) * 8;
1476                         ooff = off + sizeof(ext);
1477                         do {
1478                                 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type,
1479                                     sizeof(opt.ip6o_type), NULL, NULL,
1480                                     AF_INET6))
1481                                         goto shortpkt;
1482                                 if (opt.ip6o_type == IP6OPT_PAD1) {
1483                                         ooff++;
1484                                         continue;
1485                                 }
1486                                 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt),
1487                                     NULL, NULL, AF_INET6))
1488                                         goto shortpkt;
1489                                 if (ooff + sizeof(opt) + opt.ip6o_len > optend)
1490                                         goto drop;
1491                                 switch (opt.ip6o_type) {
1492                                 case IP6OPT_JUMBO:
1493                                         if (h->ip6_plen != 0)
1494                                                 goto drop;
1495                                         if (!pf_pull_hdr(m, ooff, &jumbo,
1496                                             sizeof(jumbo), NULL, NULL,
1497                                             AF_INET6))
1498                                                 goto shortpkt;
1499                                         memcpy(&jumbolen, jumbo.ip6oj_jumbo_len,
1500                                             sizeof(jumbolen));
1501                                         jumbolen = ntohl(jumbolen);
1502                                         if (jumbolen <= IPV6_MAXPACKET)
1503                                                 goto drop;
1504                                         if (sizeof(struct ip6_hdr) + jumbolen !=
1505                                             m->m_pkthdr.len)
1506                                                 goto drop;
1507                                         break;
1508                                 default:
1509                                         break;
1510                                 }
1511                                 ooff += sizeof(opt) + opt.ip6o_len;
1512                         } while (ooff < optend);
1513
1514                         off = optend;
1515                         proto = ext.ip6e_nxt;
1516                         break;
1517                 default:
1518                         terminal = 1;
1519                         break;
1520                 }
1521         } while (!terminal);
1522
1523         /* jumbo payload option must be present, or plen > 0 */
1524         if (ntohs(h->ip6_plen) == 0)
1525                 plen = jumbolen;
1526         else
1527                 plen = ntohs(h->ip6_plen);
1528         if (plen == 0)
1529                 goto drop;
1530         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1531                 goto shortpkt;
1532
1533         pf_scrub_ip6(&m, r->min_ttl);
1534
1535         return (PF_PASS);
1536
1537  fragment:
1538         /* Jumbo payload packets cannot be fragmented. */
1539         plen = ntohs(h->ip6_plen);
1540         if (plen == 0 || jumbolen)
1541                 goto drop;
1542         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1543                 goto shortpkt;
1544
1545         if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6))
1546                 goto shortpkt;
1547
1548         /* Offset now points to data portion. */
1549         off += sizeof(frag);
1550
1551         /* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */
1552         if (pf_reassemble6(m0, h, &frag, off, extoff, reason) != PF_PASS)
1553                 return (PF_DROP);
1554         m = *m0;
1555         if (m == NULL)
1556                 return (PF_DROP);
1557
1558         pd->flags |= PFDESC_IP_REAS;
1559         return (PF_PASS);
1560
1561  shortpkt:
1562         REASON_SET(reason, PFRES_SHORT);
1563         if (r != NULL && r->log)
1564                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1565                     1);
1566         return (PF_DROP);
1567
1568  drop:
1569         REASON_SET(reason, PFRES_NORM);
1570         if (r != NULL && r->log)
1571                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1572                     1);
1573         return (PF_DROP);
1574 }
1575 #endif /* INET6 */
1576
1577 int
1578 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff,
1579     int off, void *h, struct pf_pdesc *pd)
1580 {
1581         struct pf_rule  *r, *rm = NULL;
1582         struct tcphdr   *th = pd->hdr.tcp;
1583         int              rewrite = 0;
1584         u_short          reason;
1585         u_int8_t         flags;
1586         sa_family_t      af = pd->af;
1587
1588         PF_RULES_RASSERT();
1589
1590         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1591         while (r != NULL) {
1592                 r->evaluations++;
1593                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1594                         r = r->skip[PF_SKIP_IFP].ptr;
1595                 else if (r->direction && r->direction != dir)
1596                         r = r->skip[PF_SKIP_DIR].ptr;
1597                 else if (r->af && r->af != af)
1598                         r = r->skip[PF_SKIP_AF].ptr;
1599                 else if (r->proto && r->proto != pd->proto)
1600                         r = r->skip[PF_SKIP_PROTO].ptr;
1601                 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af,
1602                     r->src.neg, kif, M_GETFIB(m)))
1603                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1604                 else if (r->src.port_op && !pf_match_port(r->src.port_op,
1605                             r->src.port[0], r->src.port[1], th->th_sport))
1606                         r = r->skip[PF_SKIP_SRC_PORT].ptr;
1607                 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af,
1608                     r->dst.neg, NULL, M_GETFIB(m)))
1609                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1610                 else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
1611                             r->dst.port[0], r->dst.port[1], th->th_dport))
1612                         r = r->skip[PF_SKIP_DST_PORT].ptr;
1613                 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match(
1614                             pf_osfp_fingerprint(pd, m, off, th),
1615                             r->os_fingerprint))
1616                         r = TAILQ_NEXT(r, entries);
1617                 else {
1618                         rm = r;
1619                         break;
1620                 }
1621         }
1622
1623         if (rm == NULL || rm->action == PF_NOSCRUB)
1624                 return (PF_PASS);
1625         else {
1626                 r->packets[dir == PF_OUT]++;
1627                 r->bytes[dir == PF_OUT] += pd->tot_len;
1628         }
1629
1630         if (rm->rule_flag & PFRULE_REASSEMBLE_TCP)
1631                 pd->flags |= PFDESC_TCP_NORM;
1632
1633         flags = th->th_flags;
1634         if (flags & TH_SYN) {
1635                 /* Illegal packet */
1636                 if (flags & TH_RST)
1637                         goto tcp_drop;
1638
1639                 if (flags & TH_FIN)
1640                         goto tcp_drop;
1641         } else {
1642                 /* Illegal packet */
1643                 if (!(flags & (TH_ACK|TH_RST)))
1644                         goto tcp_drop;
1645         }
1646
1647         if (!(flags & TH_ACK)) {
1648                 /* These flags are only valid if ACK is set */
1649                 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG))
1650                         goto tcp_drop;
1651         }
1652
1653         /* Check for illegal header length */
1654         if (th->th_off < (sizeof(struct tcphdr) >> 2))
1655                 goto tcp_drop;
1656
1657         /* If flags changed, or reserved data set, then adjust */
1658         if (flags != th->th_flags || th->th_x2 != 0) {
1659                 u_int16_t       ov, nv;
1660
1661                 ov = *(u_int16_t *)(&th->th_ack + 1);
1662                 th->th_flags = flags;
1663                 th->th_x2 = 0;
1664                 nv = *(u_int16_t *)(&th->th_ack + 1);
1665
1666                 th->th_sum = pf_cksum_fixup(th->th_sum, ov, nv, 0);
1667                 rewrite = 1;
1668         }
1669
1670         /* Remove urgent pointer, if TH_URG is not set */
1671         if (!(flags & TH_URG) && th->th_urp) {
1672                 th->th_sum = pf_cksum_fixup(th->th_sum, th->th_urp, 0, 0);
1673                 th->th_urp = 0;
1674                 rewrite = 1;
1675         }
1676
1677         /* Process options */
1678         if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af))
1679                 rewrite = 1;
1680
1681         /* copy back packet headers if we sanitized */
1682         if (rewrite)
1683                 m_copyback(m, off, sizeof(*th), (caddr_t)th);
1684
1685         return (PF_PASS);
1686
1687  tcp_drop:
1688         REASON_SET(&reason, PFRES_NORM);
1689         if (rm != NULL && r->log)
1690                 PFLOG_PACKET(kif, m, AF_INET, dir, reason, r, NULL, NULL, pd,
1691                     1);
1692         return (PF_DROP);
1693 }
1694
1695 int
1696 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd,
1697     struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst)
1698 {
1699         u_int32_t tsval, tsecr;
1700         u_int8_t hdr[60];
1701         u_int8_t *opt;
1702
1703         KASSERT((src->scrub == NULL),
1704             ("pf_normalize_tcp_init: src->scrub != NULL"));
1705
1706         src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT);
1707         if (src->scrub == NULL)
1708                 return (1);
1709
1710         switch (pd->af) {
1711 #ifdef INET
1712         case AF_INET: {
1713                 struct ip *h = mtod(m, struct ip *);
1714                 src->scrub->pfss_ttl = h->ip_ttl;
1715                 break;
1716         }
1717 #endif /* INET */
1718 #ifdef INET6
1719         case AF_INET6: {
1720                 struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1721                 src->scrub->pfss_ttl = h->ip6_hlim;
1722                 break;
1723         }
1724 #endif /* INET6 */
1725         }
1726
1727
1728         /*
1729          * All normalizations below are only begun if we see the start of
1730          * the connections.  They must all set an enabled bit in pfss_flags
1731          */
1732         if ((th->th_flags & TH_SYN) == 0)
1733                 return (0);
1734
1735
1736         if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub &&
1737             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1738                 /* Diddle with TCP options */
1739                 int hlen;
1740                 opt = hdr + sizeof(struct tcphdr);
1741                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1742                 while (hlen >= TCPOLEN_TIMESTAMP) {
1743                         switch (*opt) {
1744                         case TCPOPT_EOL:        /* FALLTHROUGH */
1745                         case TCPOPT_NOP:
1746                                 opt++;
1747                                 hlen--;
1748                                 break;
1749                         case TCPOPT_TIMESTAMP:
1750                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1751                                         src->scrub->pfss_flags |=
1752                                             PFSS_TIMESTAMP;
1753                                         src->scrub->pfss_ts_mod =
1754                                             htonl(arc4random());
1755
1756                                         /* note PFSS_PAWS not set yet */
1757                                         memcpy(&tsval, &opt[2],
1758                                             sizeof(u_int32_t));
1759                                         memcpy(&tsecr, &opt[6],
1760                                             sizeof(u_int32_t));
1761                                         src->scrub->pfss_tsval0 = ntohl(tsval);
1762                                         src->scrub->pfss_tsval = ntohl(tsval);
1763                                         src->scrub->pfss_tsecr = ntohl(tsecr);
1764                                         getmicrouptime(&src->scrub->pfss_last);
1765                                 }
1766                                 /* FALLTHROUGH */
1767                         default:
1768                                 hlen -= MAX(opt[1], 2);
1769                                 opt += MAX(opt[1], 2);
1770                                 break;
1771                         }
1772                 }
1773         }
1774
1775         return (0);
1776 }
1777
1778 void
1779 pf_normalize_tcp_cleanup(struct pf_state *state)
1780 {
1781         if (state->src.scrub)
1782                 uma_zfree(V_pf_state_scrub_z, state->src.scrub);
1783         if (state->dst.scrub)
1784                 uma_zfree(V_pf_state_scrub_z, state->dst.scrub);
1785
1786         /* Someday... flush the TCP segment reassembly descriptors. */
1787 }
1788
1789 int
1790 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd,
1791     u_short *reason, struct tcphdr *th, struct pf_state *state,
1792     struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback)
1793 {
1794         struct timeval uptime;
1795         u_int32_t tsval, tsecr;
1796         u_int tsval_from_last;
1797         u_int8_t hdr[60];
1798         u_int8_t *opt;
1799         int copyback = 0;
1800         int got_ts = 0;
1801
1802         KASSERT((src->scrub || dst->scrub),
1803             ("%s: src->scrub && dst->scrub!", __func__));
1804
1805         /*
1806          * Enforce the minimum TTL seen for this connection.  Negate a common
1807          * technique to evade an intrusion detection system and confuse
1808          * firewall state code.
1809          */
1810         switch (pd->af) {
1811 #ifdef INET
1812         case AF_INET: {
1813                 if (src->scrub) {
1814                         struct ip *h = mtod(m, struct ip *);
1815                         if (h->ip_ttl > src->scrub->pfss_ttl)
1816                                 src->scrub->pfss_ttl = h->ip_ttl;
1817                         h->ip_ttl = src->scrub->pfss_ttl;
1818                 }
1819                 break;
1820         }
1821 #endif /* INET */
1822 #ifdef INET6
1823         case AF_INET6: {
1824                 if (src->scrub) {
1825                         struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1826                         if (h->ip6_hlim > src->scrub->pfss_ttl)
1827                                 src->scrub->pfss_ttl = h->ip6_hlim;
1828                         h->ip6_hlim = src->scrub->pfss_ttl;
1829                 }
1830                 break;
1831         }
1832 #endif /* INET6 */
1833         }
1834
1835         if (th->th_off > (sizeof(struct tcphdr) >> 2) &&
1836             ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) ||
1837             (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) &&
1838             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1839                 /* Diddle with TCP options */
1840                 int hlen;
1841                 opt = hdr + sizeof(struct tcphdr);
1842                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1843                 while (hlen >= TCPOLEN_TIMESTAMP) {
1844                         switch (*opt) {
1845                         case TCPOPT_EOL:        /* FALLTHROUGH */
1846                         case TCPOPT_NOP:
1847                                 opt++;
1848                                 hlen--;
1849                                 break;
1850                         case TCPOPT_TIMESTAMP:
1851                                 /* Modulate the timestamps.  Can be used for
1852                                  * NAT detection, OS uptime determination or
1853                                  * reboot detection.
1854                                  */
1855
1856                                 if (got_ts) {
1857                                         /* Huh?  Multiple timestamps!? */
1858                                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1859                                                 DPFPRINTF(("multiple TS??"));
1860                                                 pf_print_state(state);
1861                                                 printf("\n");
1862                                         }
1863                                         REASON_SET(reason, PFRES_TS);
1864                                         return (PF_DROP);
1865                                 }
1866                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1867                                         memcpy(&tsval, &opt[2],
1868                                             sizeof(u_int32_t));
1869                                         if (tsval && src->scrub &&
1870                                             (src->scrub->pfss_flags &
1871                                             PFSS_TIMESTAMP)) {
1872                                                 tsval = ntohl(tsval);
1873                                                 pf_change_a(&opt[2],
1874                                                     &th->th_sum,
1875                                                     htonl(tsval +
1876                                                     src->scrub->pfss_ts_mod),
1877                                                     0);
1878                                                 copyback = 1;
1879                                         }
1880
1881                                         /* Modulate TS reply iff valid (!0) */
1882                                         memcpy(&tsecr, &opt[6],
1883                                             sizeof(u_int32_t));
1884                                         if (tsecr && dst->scrub &&
1885                                             (dst->scrub->pfss_flags &
1886                                             PFSS_TIMESTAMP)) {
1887                                                 tsecr = ntohl(tsecr)
1888                                                     - dst->scrub->pfss_ts_mod;
1889                                                 pf_change_a(&opt[6],
1890                                                     &th->th_sum, htonl(tsecr),
1891                                                     0);
1892                                                 copyback = 1;
1893                                         }
1894                                         got_ts = 1;
1895                                 }
1896                                 /* FALLTHROUGH */
1897                         default:
1898                                 hlen -= MAX(opt[1], 2);
1899                                 opt += MAX(opt[1], 2);
1900                                 break;
1901                         }
1902                 }
1903                 if (copyback) {
1904                         /* Copyback the options, caller copys back header */
1905                         *writeback = 1;
1906                         m_copyback(m, off + sizeof(struct tcphdr),
1907                             (th->th_off << 2) - sizeof(struct tcphdr), hdr +
1908                             sizeof(struct tcphdr));
1909                 }
1910         }
1911
1912
1913         /*
1914          * Must invalidate PAWS checks on connections idle for too long.
1915          * The fastest allowed timestamp clock is 1ms.  That turns out to
1916          * be about 24 days before it wraps.  XXX Right now our lowerbound
1917          * TS echo check only works for the first 12 days of a connection
1918          * when the TS has exhausted half its 32bit space
1919          */
1920 #define TS_MAX_IDLE     (24*24*60*60)
1921 #define TS_MAX_CONN     (12*24*60*60)   /* XXX remove when better tsecr check */
1922
1923         getmicrouptime(&uptime);
1924         if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) &&
1925             (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE ||
1926             time_uptime - state->creation > TS_MAX_CONN))  {
1927                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1928                         DPFPRINTF(("src idled out of PAWS\n"));
1929                         pf_print_state(state);
1930                         printf("\n");
1931                 }
1932                 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS)
1933                     | PFSS_PAWS_IDLED;
1934         }
1935         if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) &&
1936             uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) {
1937                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1938                         DPFPRINTF(("dst idled out of PAWS\n"));
1939                         pf_print_state(state);
1940                         printf("\n");
1941                 }
1942                 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS)
1943                     | PFSS_PAWS_IDLED;
1944         }
1945
1946         if (got_ts && src->scrub && dst->scrub &&
1947             (src->scrub->pfss_flags & PFSS_PAWS) &&
1948             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1949                 /* Validate that the timestamps are "in-window".
1950                  * RFC1323 describes TCP Timestamp options that allow
1951                  * measurement of RTT (round trip time) and PAWS
1952                  * (protection against wrapped sequence numbers).  PAWS
1953                  * gives us a set of rules for rejecting packets on
1954                  * long fat pipes (packets that were somehow delayed
1955                  * in transit longer than the time it took to send the
1956                  * full TCP sequence space of 4Gb).  We can use these
1957                  * rules and infer a few others that will let us treat
1958                  * the 32bit timestamp and the 32bit echoed timestamp
1959                  * as sequence numbers to prevent a blind attacker from
1960                  * inserting packets into a connection.
1961                  *
1962                  * RFC1323 tells us:
1963                  *  - The timestamp on this packet must be greater than
1964                  *    or equal to the last value echoed by the other
1965                  *    endpoint.  The RFC says those will be discarded
1966                  *    since it is a dup that has already been acked.
1967                  *    This gives us a lowerbound on the timestamp.
1968                  *        timestamp >= other last echoed timestamp
1969                  *  - The timestamp will be less than or equal to
1970                  *    the last timestamp plus the time between the
1971                  *    last packet and now.  The RFC defines the max
1972                  *    clock rate as 1ms.  We will allow clocks to be
1973                  *    up to 10% fast and will allow a total difference
1974                  *    or 30 seconds due to a route change.  And this
1975                  *    gives us an upperbound on the timestamp.
1976                  *        timestamp <= last timestamp + max ticks
1977                  *    We have to be careful here.  Windows will send an
1978                  *    initial timestamp of zero and then initialize it
1979                  *    to a random value after the 3whs; presumably to
1980                  *    avoid a DoS by having to call an expensive RNG
1981                  *    during a SYN flood.  Proof MS has at least one
1982                  *    good security geek.
1983                  *
1984                  *  - The TCP timestamp option must also echo the other
1985                  *    endpoints timestamp.  The timestamp echoed is the
1986                  *    one carried on the earliest unacknowledged segment
1987                  *    on the left edge of the sequence window.  The RFC
1988                  *    states that the host will reject any echoed
1989                  *    timestamps that were larger than any ever sent.
1990                  *    This gives us an upperbound on the TS echo.
1991                  *        tescr <= largest_tsval
1992                  *  - The lowerbound on the TS echo is a little more
1993                  *    tricky to determine.  The other endpoint's echoed
1994                  *    values will not decrease.  But there may be
1995                  *    network conditions that re-order packets and
1996                  *    cause our view of them to decrease.  For now the
1997                  *    only lowerbound we can safely determine is that
1998                  *    the TS echo will never be less than the original
1999                  *    TS.  XXX There is probably a better lowerbound.
2000                  *    Remove TS_MAX_CONN with better lowerbound check.
2001                  *        tescr >= other original TS
2002                  *
2003                  * It is also important to note that the fastest
2004                  * timestamp clock of 1ms will wrap its 32bit space in
2005                  * 24 days.  So we just disable TS checking after 24
2006                  * days of idle time.  We actually must use a 12d
2007                  * connection limit until we can come up with a better
2008                  * lowerbound to the TS echo check.
2009                  */
2010                 struct timeval delta_ts;
2011                 int ts_fudge;
2012
2013
2014                 /*
2015                  * PFTM_TS_DIFF is how many seconds of leeway to allow
2016                  * a host's timestamp.  This can happen if the previous
2017                  * packet got delayed in transit for much longer than
2018                  * this packet.
2019                  */
2020                 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0)
2021                         ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF];
2022
2023                 /* Calculate max ticks since the last timestamp */
2024 #define TS_MAXFREQ      1100            /* RFC max TS freq of 1Khz + 10% skew */
2025 #define TS_MICROSECS    1000000         /* microseconds per second */
2026                 delta_ts = uptime;
2027                 timevalsub(&delta_ts, &src->scrub->pfss_last);
2028                 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ;
2029                 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ);
2030
2031                 if ((src->state >= TCPS_ESTABLISHED &&
2032                     dst->state >= TCPS_ESTABLISHED) &&
2033                     (SEQ_LT(tsval, dst->scrub->pfss_tsecr) ||
2034                     SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) ||
2035                     (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) ||
2036                     SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) {
2037                         /* Bad RFC1323 implementation or an insertion attack.
2038                          *
2039                          * - Solaris 2.6 and 2.7 are known to send another ACK
2040                          *   after the FIN,FIN|ACK,ACK closing that carries
2041                          *   an old timestamp.
2042                          */
2043
2044                         DPFPRINTF(("Timestamp failed %c%c%c%c\n",
2045                             SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ',
2046                             SEQ_GT(tsval, src->scrub->pfss_tsval +
2047                             tsval_from_last) ? '1' : ' ',
2048                             SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ',
2049                             SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' '));
2050                         DPFPRINTF((" tsval: %u  tsecr: %u  +ticks: %u  "
2051                             "idle: %jus %lums\n",
2052                             tsval, tsecr, tsval_from_last,
2053                             (uintmax_t)delta_ts.tv_sec,
2054                             delta_ts.tv_usec / 1000));
2055                         DPFPRINTF((" src->tsval: %u  tsecr: %u\n",
2056                             src->scrub->pfss_tsval, src->scrub->pfss_tsecr));
2057                         DPFPRINTF((" dst->tsval: %u  tsecr: %u  tsval0: %u"
2058                             "\n", dst->scrub->pfss_tsval,
2059                             dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0));
2060                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
2061                                 pf_print_state(state);
2062                                 pf_print_flags(th->th_flags);
2063                                 printf("\n");
2064                         }
2065                         REASON_SET(reason, PFRES_TS);
2066                         return (PF_DROP);
2067                 }
2068
2069                 /* XXX I'd really like to require tsecr but it's optional */
2070
2071         } else if (!got_ts && (th->th_flags & TH_RST) == 0 &&
2072             ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED)
2073             || pd->p_len > 0 || (th->th_flags & TH_SYN)) &&
2074             src->scrub && dst->scrub &&
2075             (src->scrub->pfss_flags & PFSS_PAWS) &&
2076             (dst->scrub->pfss_flags & PFSS_PAWS)) {
2077                 /* Didn't send a timestamp.  Timestamps aren't really useful
2078                  * when:
2079                  *  - connection opening or closing (often not even sent).
2080                  *    but we must not let an attacker to put a FIN on a
2081                  *    data packet to sneak it through our ESTABLISHED check.
2082                  *  - on a TCP reset.  RFC suggests not even looking at TS.
2083                  *  - on an empty ACK.  The TS will not be echoed so it will
2084                  *    probably not help keep the RTT calculation in sync and
2085                  *    there isn't as much danger when the sequence numbers
2086                  *    got wrapped.  So some stacks don't include TS on empty
2087                  *    ACKs :-(
2088                  *
2089                  * To minimize the disruption to mostly RFC1323 conformant
2090                  * stacks, we will only require timestamps on data packets.
2091                  *
2092                  * And what do ya know, we cannot require timestamps on data
2093                  * packets.  There appear to be devices that do legitimate
2094                  * TCP connection hijacking.  There are HTTP devices that allow
2095                  * a 3whs (with timestamps) and then buffer the HTTP request.
2096                  * If the intermediate device has the HTTP response cache, it
2097                  * will spoof the response but not bother timestamping its
2098                  * packets.  So we can look for the presence of a timestamp in
2099                  * the first data packet and if there, require it in all future
2100                  * packets.
2101                  */
2102
2103                 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) {
2104                         /*
2105                          * Hey!  Someone tried to sneak a packet in.  Or the
2106                          * stack changed its RFC1323 behavior?!?!
2107                          */
2108                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
2109                                 DPFPRINTF(("Did not receive expected RFC1323 "
2110                                     "timestamp\n"));
2111                                 pf_print_state(state);
2112                                 pf_print_flags(th->th_flags);
2113                                 printf("\n");
2114                         }
2115                         REASON_SET(reason, PFRES_TS);
2116                         return (PF_DROP);
2117                 }
2118         }
2119
2120
2121         /*
2122          * We will note if a host sends his data packets with or without
2123          * timestamps.  And require all data packets to contain a timestamp
2124          * if the first does.  PAWS implicitly requires that all data packets be
2125          * timestamped.  But I think there are middle-man devices that hijack
2126          * TCP streams immediately after the 3whs and don't timestamp their
2127          * packets (seen in a WWW accelerator or cache).
2128          */
2129         if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags &
2130             (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) {
2131                 if (got_ts)
2132                         src->scrub->pfss_flags |= PFSS_DATA_TS;
2133                 else {
2134                         src->scrub->pfss_flags |= PFSS_DATA_NOTS;
2135                         if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub &&
2136                             (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) {
2137                                 /* Don't warn if other host rejected RFC1323 */
2138                                 DPFPRINTF(("Broken RFC1323 stack did not "
2139                                     "timestamp data packet. Disabled PAWS "
2140                                     "security.\n"));
2141                                 pf_print_state(state);
2142                                 pf_print_flags(th->th_flags);
2143                                 printf("\n");
2144                         }
2145                 }
2146         }
2147
2148
2149         /*
2150          * Update PAWS values
2151          */
2152         if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags &
2153             (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) {
2154                 getmicrouptime(&src->scrub->pfss_last);
2155                 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) ||
2156                     (src->scrub->pfss_flags & PFSS_PAWS) == 0)
2157                         src->scrub->pfss_tsval = tsval;
2158
2159                 if (tsecr) {
2160                         if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) ||
2161                             (src->scrub->pfss_flags & PFSS_PAWS) == 0)
2162                                 src->scrub->pfss_tsecr = tsecr;
2163
2164                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 &&
2165                             (SEQ_LT(tsval, src->scrub->pfss_tsval0) ||
2166                             src->scrub->pfss_tsval0 == 0)) {
2167                                 /* tsval0 MUST be the lowest timestamp */
2168                                 src->scrub->pfss_tsval0 = tsval;
2169                         }
2170
2171                         /* Only fully initialized after a TS gets echoed */
2172                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0)
2173                                 src->scrub->pfss_flags |= PFSS_PAWS;
2174                 }
2175         }
2176
2177         /* I have a dream....  TCP segment reassembly.... */
2178         return (0);
2179 }
2180
2181 static int
2182 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th,
2183     int off, sa_family_t af)
2184 {
2185         u_int16_t       *mss;
2186         int              thoff;
2187         int              opt, cnt, optlen = 0;
2188         int              rewrite = 0;
2189         u_char           opts[TCP_MAXOLEN];
2190         u_char          *optp = opts;
2191
2192         thoff = th->th_off << 2;
2193         cnt = thoff - sizeof(struct tcphdr);
2194
2195         if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt,
2196             NULL, NULL, af))
2197                 return (rewrite);
2198
2199         for (; cnt > 0; cnt -= optlen, optp += optlen) {
2200                 opt = optp[0];
2201                 if (opt == TCPOPT_EOL)
2202                         break;
2203                 if (opt == TCPOPT_NOP)
2204                         optlen = 1;
2205                 else {
2206                         if (cnt < 2)
2207                                 break;
2208                         optlen = optp[1];
2209                         if (optlen < 2 || optlen > cnt)
2210                                 break;
2211                 }
2212                 switch (opt) {
2213                 case TCPOPT_MAXSEG:
2214                         mss = (u_int16_t *)(optp + 2);
2215                         if ((ntohs(*mss)) > r->max_mss) {
2216                                 th->th_sum = pf_cksum_fixup(th->th_sum,
2217                                     *mss, htons(r->max_mss), 0);
2218                                 *mss = htons(r->max_mss);
2219                                 rewrite = 1;
2220                         }
2221                         break;
2222                 default:
2223                         break;
2224                 }
2225         }
2226
2227         if (rewrite)
2228                 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts);
2229
2230         return (rewrite);
2231 }
2232
2233 #ifdef INET
2234 static void
2235 pf_scrub_ip(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos)
2236 {
2237         struct mbuf             *m = *m0;
2238         struct ip               *h = mtod(m, struct ip *);
2239
2240         /* Clear IP_DF if no-df was requested */
2241         if (flags & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
2242                 u_int16_t ip_off = h->ip_off;
2243
2244                 h->ip_off &= htons(~IP_DF);
2245                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
2246         }
2247
2248         /* Enforce a minimum ttl, may cause endless packet loops */
2249         if (min_ttl && h->ip_ttl < min_ttl) {
2250                 u_int16_t ip_ttl = h->ip_ttl;
2251
2252                 h->ip_ttl = min_ttl;
2253                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
2254         }
2255
2256         /* Enforce tos */
2257         if (flags & PFRULE_SET_TOS) {
2258                 u_int16_t       ov, nv;
2259
2260                 ov = *(u_int16_t *)h;
2261                 h->ip_tos = tos;
2262                 nv = *(u_int16_t *)h;
2263
2264                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0);
2265         }
2266
2267         /* random-id, but not for fragments */
2268         if (flags & PFRULE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) {
2269                 uint16_t ip_id = h->ip_id;
2270
2271                 ip_fillid(h);
2272                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0);
2273         }
2274 }
2275 #endif /* INET */
2276
2277 #ifdef INET6
2278 static void
2279 pf_scrub_ip6(struct mbuf **m0, u_int8_t min_ttl)
2280 {
2281         struct mbuf             *m = *m0;
2282         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
2283
2284         /* Enforce a minimum ttl, may cause endless packet loops */
2285         if (min_ttl && h->ip6_hlim < min_ttl)
2286                 h->ip6_hlim = min_ttl;
2287 }
2288 #endif