sys/netpfil/pf/pf_norm.c

   1 /*-
   2  * Copyright 2001 Niels Provos <provos@citi.umich.edu>
   3  * Copyright 2011 Alexander Bluhm <bluhm@openbsd.org>
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  *
  26  *      $OpenBSD: pf_norm.c,v 1.114 2009/01/29 14:11:45 henning Exp $
  27  */
  28
  29 #include <sys/cdefs.h>
  30 __FBSDID("$FreeBSD$");
  31
  32 #include "opt_inet.h"
  33 #include "opt_inet6.h"
  34 #include "opt_pf.h"
  35
  36 #include <sys/param.h>
  37 #include <sys/lock.h>
  38 #include <sys/mbuf.h>
  39 #include <sys/mutex.h>
  40 #include <sys/refcount.h>
  41 #include <sys/rwlock.h>
  42 #include <sys/socket.h>
  43
  44 #include <net/if.h>
  45 #include <net/vnet.h>
  46 #include <net/pfvar.h>
  47 #include <net/if_pflog.h>
  48
  49 #include <netinet/in.h>
  50 #include <netinet/ip.h>
  51 #include <netinet/ip_var.h>
  52 #include <netinet6/ip6_var.h>
  53 #include <netinet/tcp.h>
  54 #include <netinet/tcp_fsm.h>
  55 #include <netinet/tcp_seq.h>
  56
  57 #ifdef INET6
  58 #include <netinet/ip6.h>
  59 #endif /* INET6 */
  60
  61 struct pf_frent {
  62         TAILQ_ENTRY(pf_frent)   fr_next;
  63         struct mbuf     *fe_m;
  64         uint16_t        fe_hdrlen;      /* ipv4 header lenght with ip options
  65                                            ipv6, extension, fragment header */
  66         uint16_t        fe_extoff;      /* last extension header offset or 0 */
  67         uint16_t        fe_len;         /* fragment length */
  68         uint16_t        fe_off;         /* fragment offset */
  69         uint16_t        fe_mff;         /* more fragment flag */
  70 };
  71
  72 struct pf_fragment_cmp {
  73         struct pf_addr  frc_src;
  74         struct pf_addr  frc_dst;
  75         uint32_t        frc_id;
  76         sa_family_t     frc_af;
  77         uint8_t         frc_proto;
  78         uint8_t         frc_direction;
  79 };
  80
  81 struct pf_fragment {
  82         struct pf_fragment_cmp  fr_key;
  83 #define fr_src  fr_key.frc_src
  84 #define fr_dst  fr_key.frc_dst
  85 #define fr_id   fr_key.frc_id
  86 #define fr_af   fr_key.frc_af
  87 #define fr_proto        fr_key.frc_proto
  88 #define fr_direction    fr_key.frc_direction
  89
  90         RB_ENTRY(pf_fragment) fr_entry;
  91         TAILQ_ENTRY(pf_fragment) frag_next;
  92         uint8_t         fr_flags;       /* status flags */
  93 #define PFFRAG_SEENLAST         0x0001  /* Seen the last fragment for this */
  94 #define PFFRAG_NOBUFFER         0x0002  /* Non-buffering fragment cache */
  95 #define PFFRAG_DROP             0x0004  /* Drop all fragments */
  96 #define BUFFER_FRAGMENTS(fr)    (!((fr)->fr_flags & PFFRAG_NOBUFFER))
  97         uint16_t        fr_max;         /* fragment data max */
  98         uint32_t        fr_timeout;
  99         uint16_t        fr_maxlen;      /* maximum length of single fragment */
 100         TAILQ_HEAD(pf_fragq, pf_frent) fr_queue;
 101 };
 102
 103 struct pf_fragment_tag {
 104         uint16_t        ft_hdrlen;      /* header length of reassembled pkt */
 105         uint16_t        ft_extoff;      /* last extension header offset or 0 */
 106         uint16_t        ft_maxlen;      /* maximum fragment payload length */
 107         uint32_t        ft_id;          /* fragment id */
 108 };
 109
 110 static struct mtx pf_frag_mtx;
 111 #define PF_FRAG_LOCK()          mtx_lock(&pf_frag_mtx)
 112 #define PF_FRAG_UNLOCK()        mtx_unlock(&pf_frag_mtx)
 113 #define PF_FRAG_ASSERT()        mtx_assert(&pf_frag_mtx, MA_OWNED)
 114
 115 VNET_DEFINE(uma_zone_t, pf_state_scrub_z);      /* XXX: shared with pfsync */
 116
 117 static VNET_DEFINE(uma_zone_t, pf_frent_z);
 118 #define V_pf_frent_z    VNET(pf_frent_z)
 119 static VNET_DEFINE(uma_zone_t, pf_frag_z);
 120 #define V_pf_frag_z     VNET(pf_frag_z)
 121
 122 TAILQ_HEAD(pf_fragqueue, pf_fragment);
 123 TAILQ_HEAD(pf_cachequeue, pf_fragment);
 124 static VNET_DEFINE(struct pf_fragqueue, pf_fragqueue);
 125 #define V_pf_fragqueue                  VNET(pf_fragqueue)
 126 static VNET_DEFINE(struct pf_cachequeue,        pf_cachequeue);
 127 #define V_pf_cachequeue                 VNET(pf_cachequeue)
 128 RB_HEAD(pf_frag_tree, pf_fragment);
 129 static VNET_DEFINE(struct pf_frag_tree, pf_frag_tree);
 130 #define V_pf_frag_tree                  VNET(pf_frag_tree)
 131 static VNET_DEFINE(struct pf_frag_tree, pf_cache_tree);
 132 #define V_pf_cache_tree                 VNET(pf_cache_tree)
 133 static int               pf_frag_compare(struct pf_fragment *,
 134                             struct pf_fragment *);
 135 static RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 136 static RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 137
 138 /* Private prototypes */
 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 #ifdef INET
 144 static void              pf_scrub_ip(struct mbuf **, u_int32_t, u_int8_t,
 145                             u_int8_t);
 146 static void              pf_flush_fragments(void);
 147 static struct pf_fragment *pf_find_fragment(struct pf_fragment_cmp *key,
 148                         struct pf_frag_tree *tree);
 149 struct pf_frent         *pf_create_fragment(u_short *);
 150 static int              pf_reassemble(struct mbuf **, struct ip *, int,
 151                             u_short *);
 152 int                     pf_reassemble6(struct mbuf **, struct ip6_hdr *,
 153                             struct ip6_frag *, uint16_t, uint16_t, int,
 154                             u_short *);
 155 static struct mbuf      *pf_fragcache(struct mbuf **, struct ip*,
 156                             struct pf_fragment **, int, int, int *);
 157 static struct pf_fragment *pf_fillup_fragment(struct pf_fragment_cmp *,
 158                             struct pf_frent *, u_short *);
 159 int                     pf_isfull_fragment(struct pf_fragment *);
 160 struct mbuf             *pf_join_fragment(struct pf_fragment *);
 161
 162
 163 #endif /* INET */
 164 #ifdef INET6
 165 static void              pf_scrub_ip6(struct mbuf **, u_int8_t);
 166 #endif
 167 #define DPFPRINTF(x) do {                               \
 168         if (V_pf_status.debug >= PF_DEBUG_MISC) {       \
 169                 printf("%s: ", __func__);               \
 170                 printf x ;                              \
 171         }                                               \
 172 } while(0)
 173
 174 static void
 175 pf_ip2key(struct ip *ip, int dir, struct pf_fragment_cmp *key)
 176 {
 177
 178         key->frc_src.v4 = ip->ip_src;
 179         key->frc_dst.v4 = ip->ip_dst;
 180         key->frc_af = AF_INET;
 181         key->frc_proto = ip->ip_p;
 182         key->frc_id = ip->ip_id;
 183         key->frc_direction = dir;
 184 }
 185
 186 void
 187 pf_normalize_init(void)
 188 {
 189
 190         V_pf_frag_z = uma_zcreate("pf frags", sizeof(struct pf_fragment),
 191             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 192         V_pf_frent_z = uma_zcreate("pf frag entries", sizeof(struct pf_frent),
 193             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 194         V_pf_state_scrub_z = uma_zcreate("pf state scrubs",
 195             sizeof(struct pf_state_scrub),  NULL, NULL, NULL, NULL,
 196             UMA_ALIGN_PTR, 0);
 197
 198         V_pf_limits[PF_LIMIT_FRAGS].zone = V_pf_frent_z;
 199         V_pf_limits[PF_LIMIT_FRAGS].limit = PFFRAG_FRENT_HIWAT;
 200         uma_zone_set_max(V_pf_frent_z, PFFRAG_FRENT_HIWAT);
 201         uma_zone_set_warning(V_pf_frent_z, "PF frag entries limit reached");
 202
 203         mtx_init(&pf_frag_mtx, "pf fragments", NULL, MTX_DEF);
 204
 205         TAILQ_INIT(&V_pf_fragqueue);
 206         TAILQ_INIT(&V_pf_cachequeue);
 207 }
 208
 209 void
 210 pf_normalize_cleanup(void)
 211 {
 212
 213         uma_zdestroy(V_pf_state_scrub_z);
 214         uma_zdestroy(V_pf_frent_z);
 215         uma_zdestroy(V_pf_frag_z);
 216
 217         mtx_destroy(&pf_frag_mtx);
 218 }
 219
 220 static int
 221 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b)
 222 {
 223         int     diff;
 224
 225         if ((diff = a->fr_id - b->fr_id) != 0)
 226                 return (diff);
 227         if ((diff = a->fr_proto - b->fr_proto) != 0)
 228                 return (diff);
 229         if ((diff = a->fr_af - b->fr_af) != 0)
 230                 return (diff);
 231         if ((diff = pf_addr_cmp(&a->fr_src, &b->fr_src, a->fr_af)) != 0)
 232                 return (diff);
 233         if ((diff = pf_addr_cmp(&a->fr_dst, &b->fr_dst, a->fr_af)) != 0)
 234                 return (diff);
 235         return (0);
 236 }
 237
 238 void
 239 pf_purge_expired_fragments(void)
 240 {
 241         struct pf_fragment      *frag;
 242         u_int32_t                expire = time_uptime -
 243                                     V_pf_default_rule.timeout[PFTM_FRAG];
 244
 245         PF_FRAG_LOCK();
 246         while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) {
 247                 KASSERT((BUFFER_FRAGMENTS(frag)),
 248                     ("BUFFER_FRAGMENTS(frag) == 0: %s", __FUNCTION__));
 249                 if (frag->fr_timeout > expire)
 250                         break;
 251
 252                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 253                 pf_free_fragment(frag);
 254         }
 255
 256         while ((frag = TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue)) != NULL) {
 257                 KASSERT((!BUFFER_FRAGMENTS(frag)),
 258                     ("BUFFER_FRAGMENTS(frag) != 0: %s", __FUNCTION__));
 259                 if (frag->fr_timeout > expire)
 260                         break;
 261
 262                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 263                 pf_free_fragment(frag);
 264                 KASSERT((TAILQ_EMPTY(&V_pf_cachequeue) ||
 265                     TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue) != frag),
 266                     ("!(TAILQ_EMPTY() || TAILQ_LAST() == farg): %s",
 267                     __FUNCTION__));
 268         }
 269         PF_FRAG_UNLOCK();
 270 }
 271
 272 #ifdef INET
 273 /*
 274  * Try to flush old fragments to make space for new ones
 275  */
 276 static void
 277 pf_flush_fragments(void)
 278 {
 279         struct pf_fragment      *frag, *cache;
 280         int                      goal;
 281
 282         PF_FRAG_ASSERT();
 283
 284         goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10;
 285         DPFPRINTF(("trying to free %d frag entriess\n", goal));
 286         while (goal < uma_zone_get_cur(V_pf_frent_z)) {
 287                 frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue);
 288                 if (frag)
 289                         pf_free_fragment(frag);
 290                 cache = TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue);
 291                 if (cache)
 292                         pf_free_fragment(cache);
 293                 if (frag == NULL && cache == NULL)
 294                         break;
 295         }
 296 }
 297 #endif /* INET */
 298
 299 /* Frees the fragments and all associated entries */
 300 static void
 301 pf_free_fragment(struct pf_fragment *frag)
 302 {
 303         struct pf_frent         *frent;
 304
 305         PF_FRAG_ASSERT();
 306
 307         /* Free all fragments */
 308         if (BUFFER_FRAGMENTS(frag)) {
 309                 for (frent = TAILQ_FIRST(&frag->fr_queue); frent;
 310                     frent = TAILQ_FIRST(&frag->fr_queue)) {
 311                         TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
 312
 313                         m_freem(frent->fe_m);
 314                         uma_zfree(V_pf_frent_z, frent);
 315                 }
 316         } else {
 317                 for (frent = TAILQ_FIRST(&frag->fr_queue); frent;
 318                     frent = TAILQ_FIRST(&frag->fr_queue)) {
 319                         TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
 320
 321                         KASSERT((TAILQ_EMPTY(&frag->fr_queue) ||
 322                             TAILQ_FIRST(&frag->fr_queue)->fe_off >
 323                             frent->fe_len),
 324                             ("! (TAILQ_EMPTY() || TAILQ_FIRST()->fe_off >"
 325                             " frent->fe_len): %s", __func__));
 326
 327                         uma_zfree(V_pf_frent_z, frent);
 328                 }
 329         }
 330
 331         pf_remove_fragment(frag);
 332 }
 333
 334 #ifdef INET
 335 static struct pf_fragment *
 336 pf_find_fragment(struct pf_fragment_cmp *key, struct pf_frag_tree *tree)
 337 {
 338         struct pf_fragment      *frag;
 339
 340         PF_FRAG_ASSERT();
 341
 342         frag = RB_FIND(pf_frag_tree, tree, (struct pf_fragment *)key);
 343         if (frag != NULL) {
 344                 /* XXX Are we sure we want to update the timeout? */
 345                 frag->fr_timeout = time_uptime;
 346                 if (BUFFER_FRAGMENTS(frag)) {
 347                         TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 348                         TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
 349                 } else {
 350                         TAILQ_REMOVE(&V_pf_cachequeue, frag, frag_next);
 351                         TAILQ_INSERT_HEAD(&V_pf_cachequeue, frag, frag_next);
 352                 }
 353         }
 354
 355         return (frag);
 356 }
 357 #endif /* INET */
 358
 359 /* Removes a fragment from the fragment queue and frees the fragment */
 360
 361 static void
 362 pf_remove_fragment(struct pf_fragment *frag)
 363 {
 364
 365         PF_FRAG_ASSERT();
 366
 367         if (BUFFER_FRAGMENTS(frag)) {
 368                 RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag);
 369                 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 370                 uma_zfree(V_pf_frag_z, frag);
 371         } else {
 372                 RB_REMOVE(pf_frag_tree, &V_pf_cache_tree, frag);
 373                 TAILQ_REMOVE(&V_pf_cachequeue, frag, frag_next);
 374                 uma_zfree(V_pf_frag_z, frag);
 375         }
 376 }
 377
 378 #ifdef INET
 379 struct pf_frent *
 380 pf_create_fragment(u_short *reason)
 381 {
 382         struct pf_frent *frent;
 383
 384         PF_FRAG_ASSERT();
 385
 386         frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 387         if (frent == NULL) {
 388                 pf_flush_fragments();
 389                 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 390                 if (frent == NULL) {
 391                         REASON_SET(reason, PFRES_MEMORY);
 392                         return (NULL);
 393                 }
 394         }
 395
 396         return (frent);
 397 }
 398
 399 struct pf_fragment *
 400 pf_fillup_fragment(struct pf_fragment_cmp *key, struct pf_frent *frent,
 401                 u_short *reason)
 402 {
 403         struct pf_frent         *after, *next, *prev;
 404         struct pf_fragment      *frag;
 405         uint16_t                total;
 406
 407         PF_FRAG_ASSERT();
 408
 409         /* No empty fragments. */
 410         if (frent->fe_len == 0) {
 411                 DPFPRINTF(("bad fragment: len 0"));
 412                 goto bad_fragment;
 413         }
 414
 415         /* All fragments are 8 byte aligned. */
 416         if (frent->fe_mff && (frent->fe_len & 0x7)) {
 417                 DPFPRINTF(("bad fragment: mff and len %d", frent->fe_len));
 418                 goto bad_fragment;
 419         }
 420
 421         /* Respect maximum length, IP_MAXPACKET == IPV6_MAXPACKET. */
 422         if (frent->fe_off + frent->fe_len > IP_MAXPACKET) {
 423                 DPFPRINTF(("bad fragment: max packet %d",
 424                     frent->fe_off + frent->fe_len));
 425                 goto bad_fragment;
 426         }
 427
 428         DPFPRINTF((key->frc_af == AF_INET ?
 429             "reass frag %d @ %d-%d" : "reass frag %#08x @ %d-%d",
 430             key->frc_id, frent->fe_off, frent->fe_off + frent->fe_len));
 431
 432         /* Fully buffer all of the fragments in this fragment queue. */
 433         frag = pf_find_fragment(key, &V_pf_frag_tree);
 434
 435         /* Create a new reassembly queue for this packet. */
 436         if (frag == NULL) {
 437                 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 438                 if (frag == NULL) {
 439                         pf_flush_fragments();
 440                         frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 441                         if (frag == NULL) {
 442                                 REASON_SET(reason, PFRES_MEMORY);
 443                                 goto drop_fragment;
 444                         }
 445                 }
 446
 447                 *(struct pf_fragment_cmp *)frag = *key;
 448                 frag->fr_timeout = time_second;
 449                 frag->fr_maxlen = frent->fe_len;
 450                 TAILQ_INIT(&frag->fr_queue);
 451
 452                 RB_INSERT(pf_frag_tree, &V_pf_frag_tree, frag);
 453                 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
 454
 455                 /* We do not have a previous fragment. */
 456                 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next);
 457
 458                 return (frag);
 459         }
 460
 461         KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue"));
 462
 463         /* Remember maximum fragment len for refragmentation. */
 464         if (frent->fe_len > frag->fr_maxlen)
 465                 frag->fr_maxlen = frent->fe_len;
 466
 467         /* Maximum data we have seen already. */
 468         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 469                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 470
 471         /* Non terminal fragments must have more fragments flag. */
 472         if (frent->fe_off + frent->fe_len < total && !frent->fe_mff)
 473                 goto bad_fragment;
 474
 475         /* Check if we saw the last fragment already. */
 476         if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) {
 477                 if (frent->fe_off + frent->fe_len > total ||
 478                     (frent->fe_off + frent->fe_len == total && frent->fe_mff))
 479                         goto bad_fragment;
 480         } else {
 481                 if (frent->fe_off + frent->fe_len == total && !frent->fe_mff)
 482                         goto bad_fragment;
 483         }
 484
 485         /* Find a fragment after the current one. */
 486         prev = NULL;
 487         TAILQ_FOREACH(after, &frag->fr_queue, fr_next) {
 488                 if (after->fe_off > frent->fe_off)
 489                         break;
 490                 prev = after;
 491         }
 492
 493         KASSERT(prev != NULL || after != NULL,
 494             ("prev != NULL || after != NULL"));
 495
 496         if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) {
 497                 uint16_t precut;
 498
 499                 precut = prev->fe_off + prev->fe_len - frent->fe_off;
 500                 if (precut >= frent->fe_len)
 501                         goto bad_fragment;
 502                 DPFPRINTF(("overlap -%d", precut));
 503                 m_adj(frent->fe_m, precut);
 504                 frent->fe_off += precut;
 505                 frent->fe_len -= precut;
 506         }
 507
 508         for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off;
 509             after = next) {
 510                 uint16_t aftercut;
 511
 512                 aftercut = frent->fe_off + frent->fe_len - after->fe_off;
 513                 DPFPRINTF(("adjust overlap %d", aftercut));
 514                 if (aftercut < after->fe_len) {
 515                         m_adj(after->fe_m, aftercut);
 516                         after->fe_off += aftercut;
 517                         after->fe_len -= aftercut;
 518                         break;
 519                 }
 520
 521                 /* This fragment is completely overlapped, lose it. */
 522                 next = TAILQ_NEXT(after, fr_next);
 523                 m_freem(after->fe_m);
 524                 TAILQ_REMOVE(&frag->fr_queue, after, fr_next);
 525                 uma_zfree(V_pf_frent_z, after);
 526         }
 527
 528         if (prev == NULL)
 529                 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next);
 530         else
 531                 TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next);
 532
 533         return (frag);
 534
 535 bad_fragment:
 536         REASON_SET(reason, PFRES_FRAG);
 537 drop_fragment:
 538         uma_zfree(V_pf_frent_z, frent);
 539         return (NULL);
 540 }
 541
 542 int
 543 pf_isfull_fragment(struct pf_fragment *frag)
 544 {
 545         struct pf_frent *frent, *next;
 546         uint16_t off, total;
 547
 548         /* Check if we are completely reassembled */
 549         if (TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff)
 550                 return (0);
 551
 552         /* Maximum data we have seen already */
 553         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 554                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 555
 556         /* Check if we have all the data */
 557         off = 0;
 558         for (frent = TAILQ_FIRST(&frag->fr_queue); frent; frent = next) {
 559                 next = TAILQ_NEXT(frent, fr_next);
 560
 561                 off += frent->fe_len;
 562                 if (off < total && (next == NULL || next->fe_off != off)) {
 563                         DPFPRINTF(("missing fragment at %d, next %d, total %d",
 564                             off, next == NULL ? -1 : next->fe_off, total));
 565                         return (0);
 566                 }
 567         }
 568         DPFPRINTF(("%d < %d?", off, total));
 569         if (off < total)
 570                 return (0);
 571         KASSERT(off == total, ("off == total"));
 572
 573         return (1);
 574 }
 575
 576 struct mbuf *
 577 pf_join_fragment(struct pf_fragment *frag)
 578 {
 579         struct mbuf *m, *m2;
 580         struct pf_frent *frent, *next;
 581
 582         frent = TAILQ_FIRST(&frag->fr_queue);
 583         next = TAILQ_NEXT(frent, fr_next);
 584
 585         /* Magic from ip_input. */
 586         m = frent->fe_m;
 587         m2 = m->m_next;
 588         m->m_next = NULL;
 589         m_cat(m, m2);
 590         uma_zfree(V_pf_frent_z, frent);
 591         for (frent = next; frent != NULL; frent = next) {
 592                 next = TAILQ_NEXT(frent, fr_next);
 593
 594                 m2 = frent->fe_m;
 595                 /* Strip off ip header. */
 596                 m_adj(m2, frent->fe_hdrlen);
 597                 uma_zfree(V_pf_frent_z, frent);
 598                 m_cat(m, m2);
 599         }
 600
 601         /* Remove from fragment queue. */
 602         pf_remove_fragment(frag);
 603
 604         return (m);
 605 }
 606
 607 #define FR_IP_OFF(fr)   ((ntohs((fr)->fr_ip->ip_off) & IP_OFFMASK) << 3)
 608 static int
 609 pf_reassemble(struct mbuf **m0, struct ip *ip, int dir, u_short *reason)
 610 {
 611         struct mbuf             *m = *m0;
 612         struct pf_frent         *frent;
 613         struct pf_fragment      *frag;
 614         struct pf_fragment_cmp  key;
 615         uint16_t                total, hdrlen;
 616
 617         /* Get an entry for the fragment queue */
 618         if ((frent = pf_create_fragment(reason)) == NULL)
 619                 return (PF_DROP);
 620
 621         frent->fe_m = m;
 622         frent->fe_hdrlen = ip->ip_hl << 2;
 623         frent->fe_extoff = 0;
 624         frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2);
 625         frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3;
 626         frent->fe_mff = ntohs(ip->ip_off) & IP_MF;
 627
 628         pf_ip2key(ip, dir, &key);
 629
 630         if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL)
 631                 return (PF_DROP);
 632
 633         /* The mbuf is part of the fragment entry, no direct free or access */
 634         m = *m0 = NULL;
 635
 636         if (!pf_isfull_fragment(frag))
 637                 return (PF_PASS);  /* drop because *m0 is NULL, no error */
 638
 639         /* We have all the data */
 640         frent = TAILQ_FIRST(&frag->fr_queue);
 641         KASSERT(frent != NULL, ("frent != NULL"));
 642         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 643                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 644         hdrlen = frent->fe_hdrlen;
 645
 646         m = *m0 = pf_join_fragment(frag);
 647         frag = NULL;
 648
 649         if (m->m_flags & M_PKTHDR) {
 650                 int plen = 0;
 651                 for (m = *m0; m; m = m->m_next)
 652                         plen += m->m_len;
 653                 m = *m0;
 654                 m->m_pkthdr.len = plen;
 655         }
 656
 657         ip = mtod(m, struct ip *);
 658         ip->ip_len = htons(hdrlen + total);
 659         ip->ip_off &= ~(IP_MF|IP_OFFMASK);
 660
 661         if (hdrlen + total > IP_MAXPACKET) {
 662                 DPFPRINTF(("drop: too big: %d", total));
 663                 ip->ip_len = 0;
 664                 REASON_SET(reason, PFRES_SHORT);
 665                 /* PF_DROP requires a valid mbuf *m0 in pf_test() */
 666                 return (PF_DROP);
 667         }
 668
 669         DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len)));
 670         return (PF_PASS);
 671 }
 672
 673 #ifdef INET6
 674 int
 675 pf_reassemble6(struct mbuf **m0, struct ip6_hdr *ip6, struct ip6_frag *fraghdr,
 676                 uint16_t hdrlen, uint16_t extoff, int dir, u_short *reason)
 677 {
 678         struct mbuf             *m = *m0;
 679         struct pf_frent         *frent;
 680         struct pf_fragment      *frag;
 681         struct pf_fragment_cmp   key;
 682         struct m_tag            *mtag;
 683         struct pf_fragment_tag  *ftag;
 684         int                      off;
 685         uint32_t                 frag_id;
 686         uint16_t                 total, maxlen;
 687         uint8_t                  proto;
 688
 689         PF_FRAG_LOCK();
 690
 691         /* Get an entry for the fragment queue. */
 692         if ((frent = pf_create_fragment(reason)) == NULL) {
 693                 PF_FRAG_UNLOCK();
 694                 return (PF_DROP);
 695         }
 696
 697         frent->fe_m = m;
 698         frent->fe_hdrlen = hdrlen;
 699         frent->fe_extoff = extoff;
 700         frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen;
 701         frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK);
 702         frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG;
 703
 704         key.frc_src.v6 = ip6->ip6_src;
 705         key.frc_dst.v6 = ip6->ip6_dst;
 706         key.frc_af = AF_INET6;
 707         /* Only the first fragment's protocol is relevant. */
 708         key.frc_proto = 0;
 709         key.frc_id = fraghdr->ip6f_ident;
 710         key.frc_direction = dir;
 711
 712         if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) {
 713                 PF_FRAG_UNLOCK();
 714                 return (PF_DROP);
 715         }
 716
 717         /* The mbuf is part of the fragment entry, no direct free or access. */
 718         m = *m0 = NULL;
 719
 720         if (!pf_isfull_fragment(frag)) {
 721                 PF_FRAG_UNLOCK();
 722                 return (PF_PASS);  /* Drop because *m0 is NULL, no error. */
 723         }
 724
 725         /* We have all the data. */
 726         extoff = frent->fe_extoff;
 727         maxlen = frag->fr_maxlen;
 728         frag_id = frag->fr_id;
 729         frent = TAILQ_FIRST(&frag->fr_queue);
 730         KASSERT(frent != NULL, ("frent != NULL"));
 731         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 732                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 733         hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag);
 734
 735         m = *m0 = pf_join_fragment(frag);
 736         frag = NULL;
 737
 738         PF_FRAG_UNLOCK();
 739
 740         /* Take protocol from first fragment header. */
 741         m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off);
 742         KASSERT(m, ("%s: short mbuf chain", __func__));
 743         proto = *(mtod(m, caddr_t) + off);
 744         m = *m0;
 745
 746         /* Delete frag6 header */
 747         if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0)
 748                 goto fail;
 749
 750         if (m->m_flags & M_PKTHDR) {
 751                 int plen = 0;
 752                 for (m = *m0; m; m = m->m_next)
 753                         plen += m->m_len;
 754                 m = *m0;
 755                 m->m_pkthdr.len = plen;
 756         }
 757
 758         if ((mtag = m_tag_get(PF_REASSEMBLED, sizeof(struct pf_fragment_tag),
 759             M_NOWAIT)) == NULL)
 760                 goto fail;
 761         ftag = (struct pf_fragment_tag *)(mtag + 1);
 762         ftag->ft_hdrlen = hdrlen;
 763         ftag->ft_extoff = extoff;
 764         ftag->ft_maxlen = maxlen;
 765         ftag->ft_id = frag_id;
 766         m_tag_prepend(m, mtag);
 767
 768         ip6 = mtod(m, struct ip6_hdr *);
 769         ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total);
 770         if (extoff) {
 771                 /* Write protocol into next field of last extension header. */
 772                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
 773                     &off);
 774                 KASSERT(m, ("%s: short mbuf chain", __func__));
 775                 *(mtod(m, char *) + off) = proto;
 776                 m = *m0;
 777         } else
 778                 ip6->ip6_nxt = proto;
 779
 780         if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) {
 781                 DPFPRINTF(("drop: too big: %d", total));
 782                 ip6->ip6_plen = 0;
 783                 REASON_SET(reason, PFRES_SHORT);
 784                 /* PF_DROP requires a valid mbuf *m0 in pf_test6(). */
 785                 return (PF_DROP);
 786         }
 787
 788         DPFPRINTF(("complete: %p(%d)", m, ntohs(ip6->ip6_plen)));
 789         return (PF_PASS);
 790
 791 fail:
 792         REASON_SET(reason, PFRES_MEMORY);
 793         /* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */
 794         return (PF_DROP);
 795 }
 796
 797 #endif
 798
 799 static struct mbuf *
 800 pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff,
 801     int drop, int *nomem)
 802 {
 803         struct mbuf             *m = *m0;
 804         struct pf_frent         *frp, *fra, *cur = NULL;
 805         int                      ip_len = ntohs(h->ip_len) - (h->ip_hl << 2);
 806         u_int16_t                off = ntohs(h->ip_off) << 3;
 807         u_int16_t                max = ip_len + off;
 808         int                      hosed = 0;
 809
 810         PF_FRAG_ASSERT();
 811         KASSERT((*frag == NULL || !BUFFER_FRAGMENTS(*frag)),
 812             ("!(*frag == NULL || !BUFFER_FRAGMENTS(*frag)): %s", __FUNCTION__));
 813
 814         /* Create a new range queue for this packet */
 815         if (*frag == NULL) {
 816                 *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 817                 if (*frag == NULL) {
 818                         pf_flush_fragments();
 819                         *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 820                         if (*frag == NULL)
 821                                 goto no_mem;
 822                 }
 823
 824                 /* Get an entry for the queue */
 825                 cur = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 826                 if (cur == NULL) {
 827                         uma_zfree(V_pf_frag_z, *frag);
 828                         *frag = NULL;
 829                         goto no_mem;
 830                 }
 831
 832                 (*frag)->fr_flags = PFFRAG_NOBUFFER;
 833                 (*frag)->fr_max = 0;
 834                 (*frag)->fr_src.v4 = h->ip_src;
 835                 (*frag)->fr_dst.v4 = h->ip_dst;
 836                 (*frag)->fr_id = h->ip_id;
 837                 (*frag)->fr_timeout = time_uptime;
 838
 839                 cur->fe_off = off;
 840                 cur->fe_len = max; /* TODO: fe_len = max - off ? */
 841                 TAILQ_INIT(&(*frag)->fr_queue);
 842                 TAILQ_INSERT_HEAD(&(*frag)->fr_queue, cur, fr_next);
 843
 844                 RB_INSERT(pf_frag_tree, &V_pf_cache_tree, *frag);
 845                 TAILQ_INSERT_HEAD(&V_pf_cachequeue, *frag, frag_next);
 846
 847                 DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max));
 848
 849                 goto pass;
 850         }
 851
 852         /*
 853          * Find a fragment after the current one:
 854          *  - off contains the real shifted offset.
 855          */
 856         frp = NULL;
 857         TAILQ_FOREACH(fra, &(*frag)->fr_queue, fr_next) {
 858                 if (fra->fe_off > off)
 859                         break;
 860                 frp = fra;
 861         }
 862
 863         KASSERT((frp != NULL || fra != NULL),
 864             ("!(frp != NULL || fra != NULL): %s", __FUNCTION__));
 865
 866         if (frp != NULL) {
 867                 int     precut;
 868
 869                 precut = frp->fe_len - off;
 870                 if (precut >= ip_len) {
 871                         /* Fragment is entirely a duplicate */
 872                         DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n",
 873                             h->ip_id, frp->fe_off, frp->fe_len, off, max));
 874                         goto drop_fragment;
 875                 }
 876                 if (precut == 0) {
 877                         /* They are adjacent.  Fixup cache entry */
 878                         DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n",
 879                             h->ip_id, frp->fe_off, frp->fe_len, off, max));
 880                         frp->fe_len = max;
 881                 } else if (precut > 0) {
 882                         /* The first part of this payload overlaps with a
 883                          * fragment that has already been passed.
 884                          * Need to trim off the first part of the payload.
 885                          * But to do so easily, we need to create another
 886                          * mbuf to throw the original header into.
 887                          */
 888
 889                         DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n",
 890                             h->ip_id, precut, frp->fe_off, frp->fe_len, off,
 891                             max));
 892
 893                         off += precut;
 894                         max -= precut;
 895                         /* Update the previous frag to encompass this one */
 896                         frp->fe_len = max;
 897
 898                         if (!drop) {
 899                                 /* XXX Optimization opportunity
 900                                  * This is a very heavy way to trim the payload.
 901                                  * we could do it much faster by diddling mbuf
 902                                  * internals but that would be even less legible
 903                                  * than this mbuf magic.  For my next trick,
 904                                  * I'll pull a rabbit out of my laptop.
 905                                  */
 906                                 *m0 = m_dup(m, M_NOWAIT);
 907                                 if (*m0 == NULL)
 908                                         goto no_mem;
 909                                 /* From KAME Project : We have missed this! */
 910                                 m_adj(*m0, (h->ip_hl << 2) -
 911                                     (*m0)->m_pkthdr.len);
 912
 913                                 KASSERT(((*m0)->m_next == NULL),
 914                                     ("(*m0)->m_next != NULL: %s",
 915                                     __FUNCTION__));
 916                                 m_adj(m, precut + (h->ip_hl << 2));
 917                                 m_cat(*m0, m);
 918                                 m = *m0;
 919                                 if (m->m_flags & M_PKTHDR) {
 920                                         int plen = 0;
 921                                         struct mbuf *t;
 922                                         for (t = m; t; t = t->m_next)
 923                                                 plen += t->m_len;
 924                                         m->m_pkthdr.len = plen;
 925                                 }
 926
 927
 928                                 h = mtod(m, struct ip *);
 929
 930                                 KASSERT(((int)m->m_len ==
 931                                     ntohs(h->ip_len) - precut),
 932                                     ("m->m_len != ntohs(h->ip_len) - precut: %s",
 933                                     __FUNCTION__));
 934                                 h->ip_off = htons(ntohs(h->ip_off) +
 935                                     (precut >> 3));
 936                                 h->ip_len = htons(ntohs(h->ip_len) - precut);
 937                         } else {
 938                                 hosed++;
 939                         }
 940                 } else {
 941                         /* There is a gap between fragments */
 942
 943                         DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n",
 944                             h->ip_id, -precut, frp->fe_off, frp->fe_len, off,
 945                             max));
 946
 947                         cur = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 948                         if (cur == NULL)
 949                                 goto no_mem;
 950
 951                         cur->fe_off = off;
 952                         cur->fe_len = max;
 953                         TAILQ_INSERT_AFTER(&(*frag)->fr_queue, frp, cur, fr_next);
 954                 }
 955         }
 956
 957         if (fra != NULL) {
 958                 int     aftercut;
 959                 int     merge = 0;
 960
 961                 aftercut = max - fra->fe_off;
 962                 if (aftercut == 0) {
 963                         /* Adjacent fragments */
 964                         DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n",
 965                             h->ip_id, off, max, fra->fe_off, fra->fe_len));
 966                         fra->fe_off = off;
 967                         merge = 1;
 968                 } else if (aftercut > 0) {
 969                         /* Need to chop off the tail of this fragment */
 970                         DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n",
 971                             h->ip_id, aftercut, off, max, fra->fe_off,
 972                             fra->fe_len));
 973                         fra->fe_off = off;
 974                         max -= aftercut;
 975
 976                         merge = 1;
 977
 978                         if (!drop) {
 979                                 m_adj(m, -aftercut);
 980                                 if (m->m_flags & M_PKTHDR) {
 981                                         int plen = 0;
 982                                         struct mbuf *t;
 983                                         for (t = m; t; t = t->m_next)
 984                                                 plen += t->m_len;
 985                                         m->m_pkthdr.len = plen;
 986                                 }
 987                                 h = mtod(m, struct ip *);
 988                                 KASSERT(((int)m->m_len == ntohs(h->ip_len) - aftercut),
 989                                     ("m->m_len != ntohs(h->ip_len) - aftercut: %s",
 990                                     __FUNCTION__));
 991                                 h->ip_len = htons(ntohs(h->ip_len) - aftercut);
 992                         } else {
 993                                 hosed++;
 994                         }
 995                 } else if (frp == NULL) {
 996                         /* There is a gap between fragments */
 997                         DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n",
 998                             h->ip_id, -aftercut, off, max, fra->fe_off,
 999                             fra->fe_len));
1000
1001                         cur = uma_zalloc(V_pf_frent_z, M_NOWAIT);
1002                         if (cur == NULL)
1003                                 goto no_mem;
1004
1005                         cur->fe_off = off;
1006                         cur->fe_len = max;
1007                         TAILQ_INSERT_HEAD(&(*frag)->fr_queue, cur, fr_next);
1008                 }
1009
1010
1011                 /* Need to glue together two separate fragment descriptors */
1012                 if (merge) {
1013                         if (cur && fra->fe_off <= cur->fe_len) {
1014                                 /* Need to merge in a previous 'cur' */
1015                                 DPFPRINTF(("fragcache[%d]: adjacent(merge "
1016                                     "%d-%d) %d-%d (%d-%d)\n",
1017                                     h->ip_id, cur->fe_off, cur->fe_len, off,
1018                                     max, fra->fe_off, fra->fe_len));
1019                                 fra->fe_off = cur->fe_off;
1020                                 TAILQ_REMOVE(&(*frag)->fr_queue, cur, fr_next);
1021                                 uma_zfree(V_pf_frent_z, cur);
1022                                 cur = NULL;
1023
1024                         } else if (frp && fra->fe_off <= frp->fe_len) {
1025                                 /* Need to merge in a modified 'frp' */
1026                                 KASSERT((cur == NULL), ("cur != NULL: %s",
1027                                     __FUNCTION__));
1028                                 DPFPRINTF(("fragcache[%d]: adjacent(merge "
1029                                     "%d-%d) %d-%d (%d-%d)\n",
1030                                     h->ip_id, frp->fe_off, frp->fe_len, off,
1031                                     max, fra->fe_off, fra->fe_len));
1032                                 fra->fe_off = frp->fe_off;
1033                                 TAILQ_REMOVE(&(*frag)->fr_queue, frp, fr_next);
1034                                 uma_zfree(V_pf_frent_z, frp);
1035                                 frp = NULL;
1036
1037                         }
1038                 }
1039         }
1040
1041         if (hosed) {
1042                 /*
1043                  * We must keep tracking the overall fragment even when
1044                  * we're going to drop it anyway so that we know when to
1045                  * free the overall descriptor.  Thus we drop the frag late.
1046                  */
1047                 goto drop_fragment;
1048         }
1049
1050
1051  pass:
1052         /* Update maximum data size */
1053         if ((*frag)->fr_max < max)
1054                 (*frag)->fr_max = max;
1055
1056         /* This is the last segment */
1057         if (!mff)
1058                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
1059
1060         /* Check if we are completely reassembled */
1061         if (((*frag)->fr_flags & PFFRAG_SEENLAST) &&
1062             TAILQ_FIRST(&(*frag)->fr_queue)->fe_off == 0 &&
1063             TAILQ_FIRST(&(*frag)->fr_queue)->fe_len == (*frag)->fr_max) {
1064                 /* Remove from fragment queue */
1065                 DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id,
1066                     (*frag)->fr_max));
1067                 pf_free_fragment(*frag);
1068                 *frag = NULL;
1069         }
1070
1071         return (m);
1072
1073  no_mem:
1074         *nomem = 1;
1075
1076         /* Still need to pay attention to !IP_MF */
1077         if (!mff && *frag != NULL)
1078                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
1079
1080         m_freem(m);
1081         return (NULL);
1082
1083  drop_fragment:
1084
1085         /* Still need to pay attention to !IP_MF */
1086         if (!mff && *frag != NULL)
1087                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
1088
1089         if (drop) {
1090                 /* This fragment has been deemed bad.  Don't reass */
1091                 if (((*frag)->fr_flags & PFFRAG_DROP) == 0)
1092                         DPFPRINTF(("fragcache[%d]: dropping overall fragment\n",
1093                             h->ip_id));
1094                 (*frag)->fr_flags |= PFFRAG_DROP;
1095         }
1096
1097         m_freem(m);
1098         return (NULL);
1099 }
1100
1101 int
1102 pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag)
1103 {
1104         struct mbuf             *m = *m0, *t;
1105         struct pf_fragment_tag  *ftag = (struct pf_fragment_tag *)(mtag + 1);
1106         struct pf_pdesc          pd;
1107         uint32_t                 frag_id;
1108         uint16_t                 hdrlen, extoff, maxlen;
1109         uint8_t                  proto;
1110         int                      error, action;
1111
1112         hdrlen = ftag->ft_hdrlen;
1113         extoff = ftag->ft_extoff;
1114         maxlen = ftag->ft_maxlen;
1115         frag_id = ftag->ft_id;
1116         m_tag_delete(m, mtag);
1117         mtag = NULL;
1118         ftag = NULL;
1119
1120         if (extoff) {
1121                 int off;
1122
1123                 /* Use protocol from next field of last extension header */
1124                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
1125                     &off);
1126                 KASSERT((m != NULL), ("pf_refragment6: short mbuf chain"));
1127                 proto = *(mtod(m, caddr_t) + off);
1128                 *(mtod(m, char *) + off) = IPPROTO_FRAGMENT;
1129                 m = *m0;
1130         } else {
1131                 struct ip6_hdr *hdr;
1132
1133                 hdr = mtod(m, struct ip6_hdr *);
1134                 proto = hdr->ip6_nxt;
1135                 hdr->ip6_nxt = IPPROTO_FRAGMENT;
1136         }
1137
1138         /*
1139          * Maxlen may be less than 8 if there was only a single
1140          * fragment.  As it was fragmented before, add a fragment
1141          * header also for a single fragment.  If total or maxlen
1142          * is less than 8, ip6_fragment() will return EMSGSIZE and
1143          * we drop the packet.
1144          */
1145         error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id);
1146         m = (*m0)->m_nextpkt;
1147         (*m0)->m_nextpkt = NULL;
1148         if (error == 0) {
1149                 /* The first mbuf contains the unfragmented packet. */
1150                 m_freem(*m0);
1151                 *m0 = NULL;
1152                 action = PF_PASS;
1153         } else {
1154                 /* Drop expects an mbuf to free. */
1155                 DPFPRINTF(("refragment error %d", error));
1156                 action = PF_DROP;
1157         }
1158         for (t = m; m; m = t) {
1159                 t = m->m_nextpkt;
1160                 m->m_nextpkt = NULL;
1161                 memset(&pd, 0, sizeof(pd));
1162                 pd.pf_mtag = pf_find_mtag(m);
1163                 if (error == 0)
1164                         ip6_forward(m, 0);
1165                 else
1166                         m_freem(m);
1167         }
1168
1169         return (action);
1170 }
1171
1172 int
1173 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason,
1174     struct pf_pdesc *pd)
1175 {
1176         struct mbuf             *m = *m0;
1177         struct pf_rule          *r;
1178         struct pf_fragment      *frag = NULL;
1179         struct pf_fragment_cmp  key;
1180         struct ip               *h = mtod(m, struct ip *);
1181         int                      mff = (ntohs(h->ip_off) & IP_MF);
1182         int                      hlen = h->ip_hl << 2;
1183         u_int16_t                fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
1184         u_int16_t                max;
1185         int                      ip_len;
1186         int                      ip_off;
1187         int                      tag = -1;
1188         int                      verdict;
1189
1190         PF_RULES_RASSERT();
1191
1192         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1193         while (r != NULL) {
1194                 r->evaluations++;
1195                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1196                         r = r->skip[PF_SKIP_IFP].ptr;
1197                 else if (r->direction && r->direction != dir)
1198                         r = r->skip[PF_SKIP_DIR].ptr;
1199                 else if (r->af && r->af != AF_INET)
1200                         r = r->skip[PF_SKIP_AF].ptr;
1201                 else if (r->proto && r->proto != h->ip_p)
1202                         r = r->skip[PF_SKIP_PROTO].ptr;
1203                 else if (PF_MISMATCHAW(&r->src.addr,
1204                     (struct pf_addr *)&h->ip_src.s_addr, AF_INET,
1205                     r->src.neg, kif, M_GETFIB(m)))
1206                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1207                 else if (PF_MISMATCHAW(&r->dst.addr,
1208                     (struct pf_addr *)&h->ip_dst.s_addr, AF_INET,
1209                     r->dst.neg, NULL, M_GETFIB(m)))
1210                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1211                 else if (r->match_tag && !pf_match_tag(m, r, &tag,
1212                     pd->pf_mtag ? pd->pf_mtag->tag : 0))
1213                         r = TAILQ_NEXT(r, entries);
1214                 else
1215                         break;
1216         }
1217
1218         if (r == NULL || r->action == PF_NOSCRUB)
1219                 return (PF_PASS);
1220         else {
1221                 r->packets[dir == PF_OUT]++;
1222                 r->bytes[dir == PF_OUT] += pd->tot_len;
1223         }
1224
1225         /* Check for illegal packets */
1226         if (hlen < (int)sizeof(struct ip))
1227                 goto drop;
1228
1229         if (hlen > ntohs(h->ip_len))
1230                 goto drop;
1231
1232         /* Clear IP_DF if the rule uses the no-df option */
1233         if (r->rule_flag & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
1234                 u_int16_t ip_off = h->ip_off;
1235
1236                 h->ip_off &= htons(~IP_DF);
1237                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1238         }
1239
1240         /* We will need other tests here */
1241         if (!fragoff && !mff)
1242                 goto no_fragment;
1243
1244         /* We're dealing with a fragment now. Don't allow fragments
1245          * with IP_DF to enter the cache. If the flag was cleared by
1246          * no-df above, fine. Otherwise drop it.
1247          */
1248         if (h->ip_off & htons(IP_DF)) {
1249                 DPFPRINTF(("IP_DF\n"));
1250                 goto bad;
1251         }
1252
1253         ip_len = ntohs(h->ip_len) - hlen;
1254         ip_off = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
1255
1256         /* All fragments are 8 byte aligned */
1257         if (mff && (ip_len & 0x7)) {
1258                 DPFPRINTF(("mff and %d\n", ip_len));
1259                 goto bad;
1260         }
1261
1262         /* Respect maximum length */
1263         if (fragoff + ip_len > IP_MAXPACKET) {
1264                 DPFPRINTF(("max packet %d\n", fragoff + ip_len));
1265                 goto bad;
1266         }
1267         max = fragoff + ip_len;
1268
1269         if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) {
1270
1271                 /* Fully buffer all of the fragments */
1272                 PF_FRAG_LOCK();
1273
1274                 pf_ip2key(h, dir, &key);
1275                 frag = pf_find_fragment(&key, &V_pf_frag_tree);
1276
1277                 /* Check if we saw the last fragment already */
1278                 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
1279                     max > frag->fr_max)
1280                         goto bad;
1281
1282                 /* Might return a completely reassembled mbuf, or NULL */
1283                 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
1284                 verdict = pf_reassemble(m0, h, dir, reason);
1285                 PF_FRAG_UNLOCK();
1286
1287                 if (verdict != PF_PASS)
1288                         return (PF_DROP);
1289
1290                 m = *m0;
1291                 if (m == NULL)
1292                         return (PF_DROP);
1293
1294                 /* use mtag from concatenated mbuf chain */
1295                 pd->pf_mtag = pf_find_mtag(m);
1296 #ifdef DIAGNOSTIC
1297                 if (pd->pf_mtag == NULL) {
1298                         printf("%s: pf_find_mtag returned NULL(1)\n", __func__);
1299                         if ((pd->pf_mtag = pf_get_mtag(m)) == NULL) {
1300                                 m_freem(m);
1301                                 *m0 = NULL;
1302                                 goto no_mem;
1303                         }
1304                 }
1305 #endif
1306                 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
1307                         goto drop;
1308
1309                 h = mtod(m, struct ip *);
1310         } else {
1311                 /* non-buffering fragment cache (drops or masks overlaps) */
1312                 int     nomem = 0;
1313
1314                 if (dir == PF_OUT && pd->pf_mtag->flags & PF_TAG_FRAGCACHE) {
1315                         /*
1316                          * Already passed the fragment cache in the
1317                          * input direction.  If we continued, it would
1318                          * appear to be a dup and would be dropped.
1319                          */
1320                         goto fragment_pass;
1321                 }
1322
1323                 PF_FRAG_LOCK();
1324                 pf_ip2key(h, dir, &key);
1325                 frag = pf_find_fragment(&key, &V_pf_cache_tree);
1326
1327                 /* Check if we saw the last fragment already */
1328                 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
1329                     max > frag->fr_max) {
1330                         if (r->rule_flag & PFRULE_FRAGDROP)
1331                                 frag->fr_flags |= PFFRAG_DROP;
1332                         goto bad;
1333                 }
1334
1335                 *m0 = m = pf_fragcache(m0, h, &frag, mff,
1336                     (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem);
1337                 PF_FRAG_UNLOCK();
1338                 if (m == NULL) {
1339                         if (nomem)
1340                                 goto no_mem;
1341                         goto drop;
1342                 }
1343
1344                 /* use mtag from copied and trimmed mbuf chain */
1345                 pd->pf_mtag = pf_find_mtag(m);
1346 #ifdef DIAGNOSTIC
1347                 if (pd->pf_mtag == NULL) {
1348                         printf("%s: pf_find_mtag returned NULL(2)\n", __func__);
1349                         if ((pd->pf_mtag = pf_get_mtag(m)) == NULL) {
1350                                 m_freem(m);
1351                                 *m0 = NULL;
1352                                 goto no_mem;
1353                         }
1354                 }
1355 #endif
1356                 if (dir == PF_IN)
1357                         pd->pf_mtag->flags |= PF_TAG_FRAGCACHE;
1358
1359                 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
1360                         goto drop;
1361                 goto fragment_pass;
1362         }
1363
1364  no_fragment:
1365         /* At this point, only IP_DF is allowed in ip_off */
1366         if (h->ip_off & ~htons(IP_DF)) {
1367                 u_int16_t ip_off = h->ip_off;
1368
1369                 h->ip_off &= htons(IP_DF);
1370                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1371         }
1372
1373         /* not missing a return here */
1374
1375  fragment_pass:
1376         pf_scrub_ip(&m, r->rule_flag, r->min_ttl, r->set_tos);
1377
1378         if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0)
1379                 pd->flags |= PFDESC_IP_REAS;
1380         return (PF_PASS);
1381
1382  no_mem:
1383         REASON_SET(reason, PFRES_MEMORY);
1384         if (r != NULL && r->log)
1385                 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
1386                     1);
1387         return (PF_DROP);
1388
1389  drop:
1390         REASON_SET(reason, PFRES_NORM);
1391         if (r != NULL && r->log)
1392                 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
1393                     1);
1394         return (PF_DROP);
1395
1396  bad:
1397         DPFPRINTF(("dropping bad fragment\n"));
1398
1399         /* Free associated fragments */
1400         if (frag != NULL) {
1401                 pf_free_fragment(frag);
1402                 PF_FRAG_UNLOCK();
1403         }
1404
1405         REASON_SET(reason, PFRES_FRAG);
1406         if (r != NULL && r->log)
1407                 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
1408                     1);
1409
1410         return (PF_DROP);
1411 }
1412 #endif
1413
1414 #ifdef INET6
1415 int
1416 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif,
1417     u_short *reason, struct pf_pdesc *pd)
1418 {
1419         struct mbuf             *m = *m0;
1420         struct pf_rule          *r;
1421         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
1422         int                      extoff;
1423         int                      off;
1424         struct ip6_ext           ext;
1425         struct ip6_opt           opt;
1426         struct ip6_opt_jumbo     jumbo;
1427         struct ip6_frag          frag;
1428         u_int32_t                jumbolen = 0, plen;
1429         int                      optend;
1430         int                      ooff;
1431         u_int8_t                 proto;
1432         int                      terminal;
1433
1434         PF_RULES_RASSERT();
1435
1436         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1437         while (r != NULL) {
1438                 r->evaluations++;
1439                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1440                         r = r->skip[PF_SKIP_IFP].ptr;
1441                 else if (r->direction && r->direction != dir)
1442                         r = r->skip[PF_SKIP_DIR].ptr;
1443                 else if (r->af && r->af != AF_INET6)
1444                         r = r->skip[PF_SKIP_AF].ptr;
1445 #if 0 /* header chain! */
1446                 else if (r->proto && r->proto != h->ip6_nxt)
1447                         r = r->skip[PF_SKIP_PROTO].ptr;
1448 #endif
1449                 else if (PF_MISMATCHAW(&r->src.addr,
1450                     (struct pf_addr *)&h->ip6_src, AF_INET6,
1451                     r->src.neg, kif, M_GETFIB(m)))
1452                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1453                 else if (PF_MISMATCHAW(&r->dst.addr,
1454                     (struct pf_addr *)&h->ip6_dst, AF_INET6,
1455                     r->dst.neg, NULL, M_GETFIB(m)))
1456                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1457                 else
1458                         break;
1459         }
1460
1461         if (r == NULL || r->action == PF_NOSCRUB)
1462                 return (PF_PASS);
1463         else {
1464                 r->packets[dir == PF_OUT]++;
1465                 r->bytes[dir == PF_OUT] += pd->tot_len;
1466         }
1467
1468         /* Check for illegal packets */
1469         if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len)
1470                 goto drop;
1471
1472         extoff = 0;
1473         off = sizeof(struct ip6_hdr);
1474         proto = h->ip6_nxt;
1475         terminal = 0;
1476         do {
1477                 switch (proto) {
1478                 case IPPROTO_FRAGMENT:
1479                         goto fragment;
1480                         break;
1481                 case IPPROTO_AH:
1482                 case IPPROTO_ROUTING:
1483                 case IPPROTO_DSTOPTS:
1484                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1485                             NULL, AF_INET6))
1486                                 goto shortpkt;
1487                         extoff = off;
1488                         if (proto == IPPROTO_AH)
1489                                 off += (ext.ip6e_len + 2) * 4;
1490                         else
1491                                 off += (ext.ip6e_len + 1) * 8;
1492                         proto = ext.ip6e_nxt;
1493                         break;
1494                 case IPPROTO_HOPOPTS:
1495                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1496                             NULL, AF_INET6))
1497                                 goto shortpkt;
1498                         extoff = off;
1499                         optend = off + (ext.ip6e_len + 1) * 8;
1500                         ooff = off + sizeof(ext);
1501                         do {
1502                                 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type,
1503                                     sizeof(opt.ip6o_type), NULL, NULL,
1504                                     AF_INET6))
1505                                         goto shortpkt;
1506                                 if (opt.ip6o_type == IP6OPT_PAD1) {
1507                                         ooff++;
1508                                         continue;
1509                                 }
1510                                 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt),
1511                                     NULL, NULL, AF_INET6))
1512                                         goto shortpkt;
1513                                 if (ooff + sizeof(opt) + opt.ip6o_len > optend)
1514                                         goto drop;
1515                                 switch (opt.ip6o_type) {
1516                                 case IP6OPT_JUMBO:
1517                                         if (h->ip6_plen != 0)
1518                                                 goto drop;
1519                                         if (!pf_pull_hdr(m, ooff, &jumbo,
1520                                             sizeof(jumbo), NULL, NULL,
1521                                             AF_INET6))
1522                                                 goto shortpkt;
1523                                         memcpy(&jumbolen, jumbo.ip6oj_jumbo_len,
1524                                             sizeof(jumbolen));
1525                                         jumbolen = ntohl(jumbolen);
1526                                         if (jumbolen <= IPV6_MAXPACKET)
1527                                                 goto drop;
1528                                         if (sizeof(struct ip6_hdr) + jumbolen !=
1529                                             m->m_pkthdr.len)
1530                                                 goto drop;
1531                                         break;
1532                                 default:
1533                                         break;
1534                                 }
1535                                 ooff += sizeof(opt) + opt.ip6o_len;
1536                         } while (ooff < optend);
1537
1538                         off = optend;
1539                         proto = ext.ip6e_nxt;
1540                         break;
1541                 default:
1542                         terminal = 1;
1543                         break;
1544                 }
1545         } while (!terminal);
1546
1547         /* jumbo payload option must be present, or plen > 0 */
1548         if (ntohs(h->ip6_plen) == 0)
1549                 plen = jumbolen;
1550         else
1551                 plen = ntohs(h->ip6_plen);
1552         if (plen == 0)
1553                 goto drop;
1554         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1555                 goto shortpkt;
1556
1557         pf_scrub_ip6(&m, r->min_ttl);
1558
1559         return (PF_PASS);
1560
1561  fragment:
1562         /* Jumbo payload packets cannot be fragmented. */
1563         plen = ntohs(h->ip6_plen);
1564         if (plen == 0 || jumbolen)
1565                 goto drop;
1566         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1567                 goto shortpkt;
1568
1569         if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6))
1570                 goto shortpkt;
1571
1572         /* Offset now points to data portion. */
1573         off += sizeof(frag);
1574
1575         /* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */
1576         if (pf_reassemble6(m0, h, &frag, off, extoff, dir, reason) != PF_PASS)
1577                 return (PF_DROP);
1578         m = *m0;
1579         if (m == NULL)
1580                 return (PF_DROP);
1581
1582         pd->flags |= PFDESC_IP_REAS;
1583         return (PF_PASS);
1584
1585  shortpkt:
1586         REASON_SET(reason, PFRES_SHORT);
1587         if (r != NULL && r->log)
1588                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1589                     1);
1590         return (PF_DROP);
1591
1592  drop:
1593         REASON_SET(reason, PFRES_NORM);
1594         if (r != NULL && r->log)
1595                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1596                     1);
1597         return (PF_DROP);
1598 }
1599 #endif /* INET6 */
1600
1601 int
1602 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff,
1603     int off, void *h, struct pf_pdesc *pd)
1604 {
1605         struct pf_rule  *r, *rm = NULL;
1606         struct tcphdr   *th = pd->hdr.tcp;
1607         int              rewrite = 0;
1608         u_short          reason;
1609         u_int8_t         flags;
1610         sa_family_t      af = pd->af;
1611
1612         PF_RULES_RASSERT();
1613
1614         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1615         while (r != NULL) {
1616                 r->evaluations++;
1617                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1618                         r = r->skip[PF_SKIP_IFP].ptr;
1619                 else if (r->direction && r->direction != dir)
1620                         r = r->skip[PF_SKIP_DIR].ptr;
1621                 else if (r->af && r->af != af)
1622                         r = r->skip[PF_SKIP_AF].ptr;
1623                 else if (r->proto && r->proto != pd->proto)
1624                         r = r->skip[PF_SKIP_PROTO].ptr;
1625                 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af,
1626                     r->src.neg, kif, M_GETFIB(m)))
1627                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1628                 else if (r->src.port_op && !pf_match_port(r->src.port_op,
1629                             r->src.port[0], r->src.port[1], th->th_sport))
1630                         r = r->skip[PF_SKIP_SRC_PORT].ptr;
1631                 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af,
1632                     r->dst.neg, NULL, M_GETFIB(m)))
1633                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1634                 else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
1635                             r->dst.port[0], r->dst.port[1], th->th_dport))
1636                         r = r->skip[PF_SKIP_DST_PORT].ptr;
1637                 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match(
1638                             pf_osfp_fingerprint(pd, m, off, th),
1639                             r->os_fingerprint))
1640                         r = TAILQ_NEXT(r, entries);
1641                 else {
1642                         rm = r;
1643                         break;
1644                 }
1645         }
1646
1647         if (rm == NULL || rm->action == PF_NOSCRUB)
1648                 return (PF_PASS);
1649         else {
1650                 r->packets[dir == PF_OUT]++;
1651                 r->bytes[dir == PF_OUT] += pd->tot_len;
1652         }
1653
1654         if (rm->rule_flag & PFRULE_REASSEMBLE_TCP)
1655                 pd->flags |= PFDESC_TCP_NORM;
1656
1657         flags = th->th_flags;
1658         if (flags & TH_SYN) {
1659                 /* Illegal packet */
1660                 if (flags & TH_RST)
1661                         goto tcp_drop;
1662
1663                 if (flags & TH_FIN)
1664                         goto tcp_drop;
1665         } else {
1666                 /* Illegal packet */
1667                 if (!(flags & (TH_ACK|TH_RST)))
1668                         goto tcp_drop;
1669         }
1670
1671         if (!(flags & TH_ACK)) {
1672                 /* These flags are only valid if ACK is set */
1673                 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG))
1674                         goto tcp_drop;
1675         }
1676
1677         /* Check for illegal header length */
1678         if (th->th_off < (sizeof(struct tcphdr) >> 2))
1679                 goto tcp_drop;
1680
1681         /* If flags changed, or reserved data set, then adjust */
1682         if (flags != th->th_flags || th->th_x2 != 0) {
1683                 u_int16_t       ov, nv;
1684
1685                 ov = *(u_int16_t *)(&th->th_ack + 1);
1686                 th->th_flags = flags;
1687                 th->th_x2 = 0;
1688                 nv = *(u_int16_t *)(&th->th_ack + 1);
1689
1690                 th->th_sum = pf_cksum_fixup(th->th_sum, ov, nv, 0);
1691                 rewrite = 1;
1692         }
1693
1694         /* Remove urgent pointer, if TH_URG is not set */
1695         if (!(flags & TH_URG) && th->th_urp) {
1696                 th->th_sum = pf_cksum_fixup(th->th_sum, th->th_urp, 0, 0);
1697                 th->th_urp = 0;
1698                 rewrite = 1;
1699         }
1700
1701         /* Process options */
1702         if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af))
1703                 rewrite = 1;
1704
1705         /* copy back packet headers if we sanitized */
1706         if (rewrite)
1707                 m_copyback(m, off, sizeof(*th), (caddr_t)th);
1708
1709         return (PF_PASS);
1710
1711  tcp_drop:
1712         REASON_SET(&reason, PFRES_NORM);
1713         if (rm != NULL && r->log)
1714                 PFLOG_PACKET(kif, m, AF_INET, dir, reason, r, NULL, NULL, pd,
1715                     1);
1716         return (PF_DROP);
1717 }
1718
1719 int
1720 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd,
1721     struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst)
1722 {
1723         u_int32_t tsval, tsecr;
1724         u_int8_t hdr[60];
1725         u_int8_t *opt;
1726
1727         KASSERT((src->scrub == NULL),
1728             ("pf_normalize_tcp_init: src->scrub != NULL"));
1729
1730         src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT);
1731         if (src->scrub == NULL)
1732                 return (1);
1733
1734         switch (pd->af) {
1735 #ifdef INET
1736         case AF_INET: {
1737                 struct ip *h = mtod(m, struct ip *);
1738                 src->scrub->pfss_ttl = h->ip_ttl;
1739                 break;
1740         }
1741 #endif /* INET */
1742 #ifdef INET6
1743         case AF_INET6: {
1744                 struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1745                 src->scrub->pfss_ttl = h->ip6_hlim;
1746                 break;
1747         }
1748 #endif /* INET6 */
1749         }
1750
1751
1752         /*
1753          * All normalizations below are only begun if we see the start of
1754          * the connections.  They must all set an enabled bit in pfss_flags
1755          */
1756         if ((th->th_flags & TH_SYN) == 0)
1757                 return (0);
1758
1759
1760         if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub &&
1761             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1762                 /* Diddle with TCP options */
1763                 int hlen;
1764                 opt = hdr + sizeof(struct tcphdr);
1765                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1766                 while (hlen >= TCPOLEN_TIMESTAMP) {
1767                         switch (*opt) {
1768                         case TCPOPT_EOL:        /* FALLTHROUGH */
1769                         case TCPOPT_NOP:
1770                                 opt++;
1771                                 hlen--;
1772                                 break;
1773                         case TCPOPT_TIMESTAMP:
1774                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1775                                         src->scrub->pfss_flags |=
1776                                             PFSS_TIMESTAMP;
1777                                         src->scrub->pfss_ts_mod =
1778                                             htonl(arc4random());
1779
1780                                         /* note PFSS_PAWS not set yet */
1781                                         memcpy(&tsval, &opt[2],
1782                                             sizeof(u_int32_t));
1783                                         memcpy(&tsecr, &opt[6],
1784                                             sizeof(u_int32_t));
1785                                         src->scrub->pfss_tsval0 = ntohl(tsval);
1786                                         src->scrub->pfss_tsval = ntohl(tsval);
1787                                         src->scrub->pfss_tsecr = ntohl(tsecr);
1788                                         getmicrouptime(&src->scrub->pfss_last);
1789                                 }
1790                                 /* FALLTHROUGH */
1791                         default:
1792                                 hlen -= MAX(opt[1], 2);
1793                                 opt += MAX(opt[1], 2);
1794                                 break;
1795                         }
1796                 }
1797         }
1798
1799         return (0);
1800 }
1801
1802 void
1803 pf_normalize_tcp_cleanup(struct pf_state *state)
1804 {
1805         if (state->src.scrub)
1806                 uma_zfree(V_pf_state_scrub_z, state->src.scrub);
1807         if (state->dst.scrub)
1808                 uma_zfree(V_pf_state_scrub_z, state->dst.scrub);
1809
1810         /* Someday... flush the TCP segment reassembly descriptors. */
1811 }
1812
1813 int
1814 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd,
1815     u_short *reason, struct tcphdr *th, struct pf_state *state,
1816     struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback)
1817 {
1818         struct timeval uptime;
1819         u_int32_t tsval, tsecr;
1820         u_int tsval_from_last;
1821         u_int8_t hdr[60];
1822         u_int8_t *opt;
1823         int copyback = 0;
1824         int got_ts = 0;
1825
1826         KASSERT((src->scrub || dst->scrub),
1827             ("%s: src->scrub && dst->scrub!", __func__));
1828
1829         /*
1830          * Enforce the minimum TTL seen for this connection.  Negate a common
1831          * technique to evade an intrusion detection system and confuse
1832          * firewall state code.
1833          */
1834         switch (pd->af) {
1835 #ifdef INET
1836         case AF_INET: {
1837                 if (src->scrub) {
1838                         struct ip *h = mtod(m, struct ip *);
1839                         if (h->ip_ttl > src->scrub->pfss_ttl)
1840                                 src->scrub->pfss_ttl = h->ip_ttl;
1841                         h->ip_ttl = src->scrub->pfss_ttl;
1842                 }
1843                 break;
1844         }
1845 #endif /* INET */
1846 #ifdef INET6
1847         case AF_INET6: {
1848                 if (src->scrub) {
1849                         struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1850                         if (h->ip6_hlim > src->scrub->pfss_ttl)
1851                                 src->scrub->pfss_ttl = h->ip6_hlim;
1852                         h->ip6_hlim = src->scrub->pfss_ttl;
1853                 }
1854                 break;
1855         }
1856 #endif /* INET6 */
1857         }
1858
1859         if (th->th_off > (sizeof(struct tcphdr) >> 2) &&
1860             ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) ||
1861             (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) &&
1862             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1863                 /* Diddle with TCP options */
1864                 int hlen;
1865                 opt = hdr + sizeof(struct tcphdr);
1866                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1867                 while (hlen >= TCPOLEN_TIMESTAMP) {
1868                         switch (*opt) {
1869                         case TCPOPT_EOL:        /* FALLTHROUGH */
1870                         case TCPOPT_NOP:
1871                                 opt++;
1872                                 hlen--;
1873                                 break;
1874                         case TCPOPT_TIMESTAMP:
1875                                 /* Modulate the timestamps.  Can be used for
1876                                  * NAT detection, OS uptime determination or
1877                                  * reboot detection.
1878                                  */
1879
1880                                 if (got_ts) {
1881                                         /* Huh?  Multiple timestamps!? */
1882                                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1883                                                 DPFPRINTF(("multiple TS??"));
1884                                                 pf_print_state(state);
1885                                                 printf("\n");
1886                                         }
1887                                         REASON_SET(reason, PFRES_TS);
1888                                         return (PF_DROP);
1889                                 }
1890                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1891                                         memcpy(&tsval, &opt[2],
1892                                             sizeof(u_int32_t));
1893                                         if (tsval && src->scrub &&
1894                                             (src->scrub->pfss_flags &
1895                                             PFSS_TIMESTAMP)) {
1896                                                 tsval = ntohl(tsval);
1897                                                 pf_change_a(&opt[2],
1898                                                     &th->th_sum,
1899                                                     htonl(tsval +
1900                                                     src->scrub->pfss_ts_mod),
1901                                                     0);
1902                                                 copyback = 1;
1903                                         }
1904
1905                                         /* Modulate TS reply iff valid (!0) */
1906                                         memcpy(&tsecr, &opt[6],
1907                                             sizeof(u_int32_t));
1908                                         if (tsecr && dst->scrub &&
1909                                             (dst->scrub->pfss_flags &
1910                                             PFSS_TIMESTAMP)) {
1911                                                 tsecr = ntohl(tsecr)
1912                                                     - dst->scrub->pfss_ts_mod;
1913                                                 pf_change_a(&opt[6],
1914                                                     &th->th_sum, htonl(tsecr),
1915                                                     0);
1916                                                 copyback = 1;
1917                                         }
1918                                         got_ts = 1;
1919                                 }
1920                                 /* FALLTHROUGH */
1921                         default:
1922                                 hlen -= MAX(opt[1], 2);
1923                                 opt += MAX(opt[1], 2);
1924                                 break;
1925                         }
1926                 }
1927                 if (copyback) {
1928                         /* Copyback the options, caller copys back header */
1929                         *writeback = 1;
1930                         m_copyback(m, off + sizeof(struct tcphdr),
1931                             (th->th_off << 2) - sizeof(struct tcphdr), hdr +
1932                             sizeof(struct tcphdr));
1933                 }
1934         }
1935
1936
1937         /*
1938          * Must invalidate PAWS checks on connections idle for too long.
1939          * The fastest allowed timestamp clock is 1ms.  That turns out to
1940          * be about 24 days before it wraps.  XXX Right now our lowerbound
1941          * TS echo check only works for the first 12 days of a connection
1942          * when the TS has exhausted half its 32bit space
1943          */
1944 #define TS_MAX_IDLE     (24*24*60*60)
1945 #define TS_MAX_CONN     (12*24*60*60)   /* XXX remove when better tsecr check */
1946
1947         getmicrouptime(&uptime);
1948         if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) &&
1949             (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE ||
1950             time_uptime - state->creation > TS_MAX_CONN))  {
1951                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1952                         DPFPRINTF(("src idled out of PAWS\n"));
1953                         pf_print_state(state);
1954                         printf("\n");
1955                 }
1956                 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS)
1957                     | PFSS_PAWS_IDLED;
1958         }
1959         if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) &&
1960             uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) {
1961                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1962                         DPFPRINTF(("dst idled out of PAWS\n"));
1963                         pf_print_state(state);
1964                         printf("\n");
1965                 }
1966                 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS)
1967                     | PFSS_PAWS_IDLED;
1968         }
1969
1970         if (got_ts && src->scrub && dst->scrub &&
1971             (src->scrub->pfss_flags & PFSS_PAWS) &&
1972             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1973                 /* Validate that the timestamps are "in-window".
1974                  * RFC1323 describes TCP Timestamp options that allow
1975                  * measurement of RTT (round trip time) and PAWS
1976                  * (protection against wrapped sequence numbers).  PAWS
1977                  * gives us a set of rules for rejecting packets on
1978                  * long fat pipes (packets that were somehow delayed
1979                  * in transit longer than the time it took to send the
1980                  * full TCP sequence space of 4Gb).  We can use these
1981                  * rules and infer a few others that will let us treat
1982                  * the 32bit timestamp and the 32bit echoed timestamp
1983                  * as sequence numbers to prevent a blind attacker from
1984                  * inserting packets into a connection.
1985                  *
1986                  * RFC1323 tells us:
1987                  *  - The timestamp on this packet must be greater than
1988                  *    or equal to the last value echoed by the other
1989                  *    endpoint.  The RFC says those will be discarded
1990                  *    since it is a dup that has already been acked.
1991                  *    This gives us a lowerbound on the timestamp.
1992                  *        timestamp >= other last echoed timestamp
1993                  *  - The timestamp will be less than or equal to
1994                  *    the last timestamp plus the time between the
1995                  *    last packet and now.  The RFC defines the max
1996                  *    clock rate as 1ms.  We will allow clocks to be
1997                  *    up to 10% fast and will allow a total difference
1998                  *    or 30 seconds due to a route change.  And this
1999                  *    gives us an upperbound on the timestamp.
2000                  *        timestamp <= last timestamp + max ticks
2001                  *    We have to be careful here.  Windows will send an
2002                  *    initial timestamp of zero and then initialize it
2003                  *    to a random value after the 3whs; presumably to
2004                  *    avoid a DoS by having to call an expensive RNG
2005                  *    during a SYN flood.  Proof MS has at least one
2006                  *    good security geek.
2007                  *
2008                  *  - The TCP timestamp option must also echo the other
2009                  *    endpoints timestamp.  The timestamp echoed is the
2010                  *    one carried on the earliest unacknowledged segment
2011                  *    on the left edge of the sequence window.  The RFC
2012                  *    states that the host will reject any echoed
2013                  *    timestamps that were larger than any ever sent.
2014                  *    This gives us an upperbound on the TS echo.
2015                  *        tescr <= largest_tsval
2016                  *  - The lowerbound on the TS echo is a little more
2017                  *    tricky to determine.  The other endpoint's echoed
2018                  *    values will not decrease.  But there may be
2019                  *    network conditions that re-order packets and
2020                  *    cause our view of them to decrease.  For now the
2021                  *    only lowerbound we can safely determine is that
2022                  *    the TS echo will never be less than the original
2023                  *    TS.  XXX There is probably a better lowerbound.
2024                  *    Remove TS_MAX_CONN with better lowerbound check.
2025                  *        tescr >= other original TS
2026                  *
2027                  * It is also important to note that the fastest
2028                  * timestamp clock of 1ms will wrap its 32bit space in
2029                  * 24 days.  So we just disable TS checking after 24
2030                  * days of idle time.  We actually must use a 12d
2031                  * connection limit until we can come up with a better
2032                  * lowerbound to the TS echo check.
2033                  */
2034                 struct timeval delta_ts;
2035                 int ts_fudge;
2036
2037
2038                 /*
2039                  * PFTM_TS_DIFF is how many seconds of leeway to allow
2040                  * a host's timestamp.  This can happen if the previous
2041                  * packet got delayed in transit for much longer than
2042                  * this packet.
2043                  */
2044                 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0)
2045                         ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF];
2046
2047                 /* Calculate max ticks since the last timestamp */
2048 #define TS_MAXFREQ      1100            /* RFC max TS freq of 1Khz + 10% skew */
2049 #define TS_MICROSECS    1000000         /* microseconds per second */
2050                 delta_ts = uptime;
2051                 timevalsub(&delta_ts, &src->scrub->pfss_last);
2052                 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ;
2053                 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ);
2054
2055                 if ((src->state >= TCPS_ESTABLISHED &&
2056                     dst->state >= TCPS_ESTABLISHED) &&
2057                     (SEQ_LT(tsval, dst->scrub->pfss_tsecr) ||
2058                     SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) ||
2059                     (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) ||
2060                     SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) {
2061                         /* Bad RFC1323 implementation or an insertion attack.
2062                          *
2063                          * - Solaris 2.6 and 2.7 are known to send another ACK
2064                          *   after the FIN,FIN|ACK,ACK closing that carries
2065                          *   an old timestamp.
2066                          */
2067
2068                         DPFPRINTF(("Timestamp failed %c%c%c%c\n",
2069                             SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ',
2070                             SEQ_GT(tsval, src->scrub->pfss_tsval +
2071                             tsval_from_last) ? '1' : ' ',
2072                             SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ',
2073                             SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' '));
2074                         DPFPRINTF((" tsval: %u  tsecr: %u  +ticks: %u  "
2075                             "idle: %jus %lums\n",
2076                             tsval, tsecr, tsval_from_last,
2077                             (uintmax_t)delta_ts.tv_sec,
2078                             delta_ts.tv_usec / 1000));
2079                         DPFPRINTF((" src->tsval: %u  tsecr: %u\n",
2080                             src->scrub->pfss_tsval, src->scrub->pfss_tsecr));
2081                         DPFPRINTF((" dst->tsval: %u  tsecr: %u  tsval0: %u"
2082                             "\n", dst->scrub->pfss_tsval,
2083                             dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0));
2084                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
2085                                 pf_print_state(state);
2086                                 pf_print_flags(th->th_flags);
2087                                 printf("\n");
2088                         }
2089                         REASON_SET(reason, PFRES_TS);
2090                         return (PF_DROP);
2091                 }
2092
2093                 /* XXX I'd really like to require tsecr but it's optional */
2094
2095         } else if (!got_ts && (th->th_flags & TH_RST) == 0 &&
2096             ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED)
2097             || pd->p_len > 0 || (th->th_flags & TH_SYN)) &&
2098             src->scrub && dst->scrub &&
2099             (src->scrub->pfss_flags & PFSS_PAWS) &&
2100             (dst->scrub->pfss_flags & PFSS_PAWS)) {
2101                 /* Didn't send a timestamp.  Timestamps aren't really useful
2102                  * when:
2103                  *  - connection opening or closing (often not even sent).
2104                  *    but we must not let an attacker to put a FIN on a
2105                  *    data packet to sneak it through our ESTABLISHED check.
2106                  *  - on a TCP reset.  RFC suggests not even looking at TS.
2107                  *  - on an empty ACK.  The TS will not be echoed so it will
2108                  *    probably not help keep the RTT calculation in sync and
2109                  *    there isn't as much danger when the sequence numbers
2110                  *    got wrapped.  So some stacks don't include TS on empty
2111                  *    ACKs :-(
2112                  *
2113                  * To minimize the disruption to mostly RFC1323 conformant
2114                  * stacks, we will only require timestamps on data packets.
2115                  *
2116                  * And what do ya know, we cannot require timestamps on data
2117                  * packets.  There appear to be devices that do legitimate
2118                  * TCP connection hijacking.  There are HTTP devices that allow
2119                  * a 3whs (with timestamps) and then buffer the HTTP request.
2120                  * If the intermediate device has the HTTP response cache, it
2121                  * will spoof the response but not bother timestamping its
2122                  * packets.  So we can look for the presence of a timestamp in
2123                  * the first data packet and if there, require it in all future
2124                  * packets.
2125                  */
2126
2127                 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) {
2128                         /*
2129                          * Hey!  Someone tried to sneak a packet in.  Or the
2130                          * stack changed its RFC1323 behavior?!?!
2131                          */
2132                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
2133                                 DPFPRINTF(("Did not receive expected RFC1323 "
2134                                     "timestamp\n"));
2135                                 pf_print_state(state);
2136                                 pf_print_flags(th->th_flags);
2137                                 printf("\n");
2138                         }
2139                         REASON_SET(reason, PFRES_TS);
2140                         return (PF_DROP);
2141                 }
2142         }
2143
2144
2145         /*
2146          * We will note if a host sends his data packets with or without
2147          * timestamps.  And require all data packets to contain a timestamp
2148          * if the first does.  PAWS implicitly requires that all data packets be
2149          * timestamped.  But I think there are middle-man devices that hijack
2150          * TCP streams immediately after the 3whs and don't timestamp their
2151          * packets (seen in a WWW accelerator or cache).
2152          */
2153         if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags &
2154             (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) {
2155                 if (got_ts)
2156                         src->scrub->pfss_flags |= PFSS_DATA_TS;
2157                 else {
2158                         src->scrub->pfss_flags |= PFSS_DATA_NOTS;
2159                         if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub &&
2160                             (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) {
2161                                 /* Don't warn if other host rejected RFC1323 */
2162                                 DPFPRINTF(("Broken RFC1323 stack did not "
2163                                     "timestamp data packet. Disabled PAWS "
2164                                     "security.\n"));
2165                                 pf_print_state(state);
2166                                 pf_print_flags(th->th_flags);
2167                                 printf("\n");
2168                         }
2169                 }
2170         }
2171
2172
2173         /*
2174          * Update PAWS values
2175          */
2176         if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags &
2177             (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) {
2178                 getmicrouptime(&src->scrub->pfss_last);
2179                 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) ||
2180                     (src->scrub->pfss_flags & PFSS_PAWS) == 0)
2181                         src->scrub->pfss_tsval = tsval;
2182
2183                 if (tsecr) {
2184                         if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) ||
2185                             (src->scrub->pfss_flags & PFSS_PAWS) == 0)
2186                                 src->scrub->pfss_tsecr = tsecr;
2187
2188                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 &&
2189                             (SEQ_LT(tsval, src->scrub->pfss_tsval0) ||
2190                             src->scrub->pfss_tsval0 == 0)) {
2191                                 /* tsval0 MUST be the lowest timestamp */
2192                                 src->scrub->pfss_tsval0 = tsval;
2193                         }
2194
2195                         /* Only fully initialized after a TS gets echoed */
2196                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0)
2197                                 src->scrub->pfss_flags |= PFSS_PAWS;
2198                 }
2199         }
2200
2201         /* I have a dream....  TCP segment reassembly.... */
2202         return (0);
2203 }
2204
2205 static int
2206 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th,
2207     int off, sa_family_t af)
2208 {
2209         u_int16_t       *mss;
2210         int              thoff;
2211         int              opt, cnt, optlen = 0;
2212         int              rewrite = 0;
2213         u_char           opts[TCP_MAXOLEN];
2214         u_char          *optp = opts;
2215
2216         thoff = th->th_off << 2;
2217         cnt = thoff - sizeof(struct tcphdr);
2218
2219         if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt,
2220             NULL, NULL, af))
2221                 return (rewrite);
2222
2223         for (; cnt > 0; cnt -= optlen, optp += optlen) {
2224                 opt = optp[0];
2225                 if (opt == TCPOPT_EOL)
2226                         break;
2227                 if (opt == TCPOPT_NOP)
2228                         optlen = 1;
2229                 else {
2230                         if (cnt < 2)
2231                                 break;
2232                         optlen = optp[1];
2233                         if (optlen < 2 || optlen > cnt)
2234                                 break;
2235                 }
2236                 switch (opt) {
2237                 case TCPOPT_MAXSEG:
2238                         mss = (u_int16_t *)(optp + 2);
2239                         if ((ntohs(*mss)) > r->max_mss) {
2240                                 th->th_sum = pf_cksum_fixup(th->th_sum,
2241                                     *mss, htons(r->max_mss), 0);
2242                                 *mss = htons(r->max_mss);
2243                                 rewrite = 1;
2244                         }
2245                         break;
2246                 default:
2247                         break;
2248                 }
2249         }
2250
2251         if (rewrite)
2252                 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts);
2253
2254         return (rewrite);
2255 }
2256
2257 #ifdef INET
2258 static void
2259 pf_scrub_ip(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos)
2260 {
2261         struct mbuf             *m = *m0;
2262         struct ip               *h = mtod(m, struct ip *);
2263
2264         /* Clear IP_DF if no-df was requested */
2265         if (flags & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
2266                 u_int16_t ip_off = h->ip_off;
2267
2268                 h->ip_off &= htons(~IP_DF);
2269                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
2270         }
2271
2272         /* Enforce a minimum ttl, may cause endless packet loops */
2273         if (min_ttl && h->ip_ttl < min_ttl) {
2274                 u_int16_t ip_ttl = h->ip_ttl;
2275
2276                 h->ip_ttl = min_ttl;
2277                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
2278         }
2279
2280         /* Enforce tos */
2281         if (flags & PFRULE_SET_TOS) {
2282                 u_int16_t       ov, nv;
2283
2284                 ov = *(u_int16_t *)h;
2285                 h->ip_tos = tos;
2286                 nv = *(u_int16_t *)h;
2287
2288                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0);
2289         }
2290
2291         /* random-id, but not for fragments */
2292         if (flags & PFRULE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) {
2293                 u_int16_t ip_id = h->ip_id;
2294
2295                 h->ip_id = ip_randomid();
2296                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0);
2297         }
2298 }
2299 #endif /* INET */
2300
2301 #ifdef INET6
2302 static void
2303 pf_scrub_ip6(struct mbuf **m0, u_int8_t min_ttl)
2304 {
2305         struct mbuf             *m = *m0;
2306         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
2307
2308         /* Enforce a minimum ttl, may cause endless packet loops */
2309         if (min_ttl && h->ip6_hlim < min_ttl)
2310                 h->ip6_hlim = min_ttl;
2311 }
2312 #endif