sys/net/pf/pf_norm.c

   1 /*      $FreeBSD: src/sys/contrib/pf/net/pf_norm.c,v 1.10 2004/08/14 15:32:40 dwmalone Exp $    */
   2 /*      $OpenBSD: pf_norm.c,v 1.80.2.1 2004/04/30 21:46:33 brad Exp $ */
   3 /* add  $OpenBSD: pf_norm.c,v 1.87 2004/05/11 07:34:11 dhartmei Exp $ */
   4 /*      $DragonFly: src/sys/net/pf/pf_norm.c,v 1.10 2008/09/04 09:08:22 hasso Exp $ */
   5
   6 /*
   7  * Copyright (c) 2004 The DragonFly Project.  All rights reserved.
   8  *
   9  * Copyright 2001 Niels Provos <provos@citi.umich.edu>
  10  * All rights reserved.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  24  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  26  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  30  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  31  */
  32
  33 #include "opt_inet.h"
  34 #include "opt_inet6.h"
  35
  36 #include <sys/param.h>
  37 #include <sys/systm.h>
  38 #include <sys/mbuf.h>
  39 #include <sys/filio.h>
  40 #include <sys/fcntl.h>
  41 #include <sys/socket.h>
  42 #include <sys/kernel.h>
  43 #include <sys/time.h>
  44 #include <vm/vm_zone.h>
  45
  46 #include <net/if.h>
  47 #include <net/if_types.h>
  48 #include <net/bpf.h>
  49 #include <net/route.h>
  50 #include <net/pf/if_pflog.h>
  51
  52 #include <netinet/in.h>
  53 #include <netinet/in_var.h>
  54 #include <netinet/in_systm.h>
  55 #include <netinet/ip.h>
  56 #include <netinet/ip_var.h>
  57 #include <netinet/tcp.h>
  58 #include <netinet/tcp_seq.h>
  59 #include <netinet/udp.h>
  60 #include <netinet/ip_icmp.h>
  61
  62 #ifdef INET6
  63 #include <netinet/ip6.h>
  64 #endif /* INET6 */
  65
  66 #include <net/pf/pfvar.h>
  67
  68 #ifdef INET6
  69 /*
  70  * XXX: This should go to netinet/ip6.h (KAME)
  71  */
  72 #endif /* INET6 */
  73
  74 #define PFFRAG_SEENLAST 0x0001          /* Seen the last fragment for this */
  75 #define PFFRAG_NOBUFFER 0x0002          /* Non-buffering fragment cache */
  76 #define PFFRAG_DROP     0x0004          /* Drop all fragments */
  77 #define BUFFER_FRAGMENTS(fr)    (!((fr)->fr_flags & PFFRAG_NOBUFFER))
  78
  79
  80 TAILQ_HEAD(pf_fragqueue, pf_fragment)   pf_fragqueue;
  81 TAILQ_HEAD(pf_cachequeue, pf_fragment)  pf_cachequeue;
  82
  83 static int              pf_frag_compare(struct pf_fragment *,
  84                                         struct pf_fragment *);
  85 RB_HEAD(pf_frag_tree, pf_fragment)      pf_frag_tree, pf_cache_tree;
  86 RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
  87 RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
  88
  89 /* Private prototypes */
  90 void                     pf_ip2key(struct pf_fragment *, struct ip *);
  91 void                     pf_remove_fragment(struct pf_fragment *);
  92 void                     pf_flush_fragments(void);
  93 void                     pf_free_fragment(struct pf_fragment *);
  94 struct pf_fragment      *pf_find_fragment(struct ip *, struct pf_frag_tree *);
  95 struct mbuf             *pf_reassemble(struct mbuf **, struct pf_fragment **,
  96                             struct pf_frent *, int);
  97 struct mbuf             *pf_fragcache(struct mbuf **, struct ip*,
  98                             struct pf_fragment **, int, int, int *);
  99 u_int16_t                pf_cksum_fixup(u_int16_t, u_int16_t, u_int16_t);
 100 int                      pf_normalize_tcpopt(struct pf_rule *, struct mbuf *,
 101                             struct tcphdr *, int);
 102
 103 #define DPFPRINTF(x)    if (pf_status.debug >= PF_DEBUG_MISC) \
 104                             { kprintf("%s: ", __func__); kprintf x ;}
 105
 106 /* Globals */
 107 vm_zone_t                pf_frent_pl, pf_frag_pl, pf_cache_pl, pf_cent_pl;
 108 vm_zone_t                pf_state_scrub_pl;
 109 int                      pf_nfrents, pf_ncache;
 110
 111 void
 112 pf_normalize_init(void)
 113 {
 114         /* XXX
 115         pool_sethiwat(&pf_frag_pl, PFFRAG_FRAG_HIWAT);
 116         pool_sethardlimit(&pf_frent_pl, PFFRAG_FRENT_HIWAT, NULL, 0);
 117         pool_sethardlimit(&pf_cache_pl, PFFRAG_FRCACHE_HIWAT, NULL, 0);
 118         pool_sethardlimit(&pf_cent_pl, PFFRAG_FRCENT_HIWAT, NULL, 0);
 119         */
 120
 121         TAILQ_INIT(&pf_fragqueue);
 122         TAILQ_INIT(&pf_cachequeue);
 123 }
 124
 125 static int
 126 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b)
 127 {
 128         int     diff;
 129
 130         if ((diff = a->fr_id - b->fr_id))
 131                 return (diff);
 132         else if ((diff = a->fr_p - b->fr_p))
 133                 return (diff);
 134         else if (a->fr_src.s_addr < b->fr_src.s_addr)
 135                 return (-1);
 136         else if (a->fr_src.s_addr > b->fr_src.s_addr)
 137                 return (1);
 138         else if (a->fr_dst.s_addr < b->fr_dst.s_addr)
 139                 return (-1);
 140         else if (a->fr_dst.s_addr > b->fr_dst.s_addr)
 141                 return (1);
 142         return (0);
 143 }
 144
 145 void
 146 pf_purge_expired_fragments(void)
 147 {
 148         struct pf_fragment      *frag;
 149         u_int32_t                expire = time_second -
 150                                     pf_default_rule.timeout[PFTM_FRAG];
 151
 152         while ((frag = TAILQ_LAST(&pf_fragqueue, pf_fragqueue)) != NULL) {
 153                 KASSERT((BUFFER_FRAGMENTS(frag)),
 154                         ("BUFFER_FRAGMENTS(frag) == 0: %s", __func__));
 155                 if (frag->fr_timeout > expire)
 156                         break;
 157
 158                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 159                 pf_free_fragment(frag);
 160         }
 161
 162         while ((frag = TAILQ_LAST(&pf_cachequeue, pf_cachequeue)) != NULL) {
 163                 KASSERT((!BUFFER_FRAGMENTS(frag)),
 164                         ("BUFFER_FRAGMENTS(frag) != 0: %s", __func__));
 165                 if (frag->fr_timeout > expire)
 166                         break;
 167
 168                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 169                 pf_free_fragment(frag);
 170                 KASSERT((TAILQ_EMPTY(&pf_cachequeue) ||
 171                     TAILQ_LAST(&pf_cachequeue, pf_cachequeue) != frag),
 172                     ("!(TAILQ_EMPTY() || TAILQ_LAST() == farg): %s",
 173                     __func__));
 174         }
 175 }
 176
 177 /*
 178  * Try to flush old fragments to make space for new ones
 179  */
 180
 181 void
 182 pf_flush_fragments(void)
 183 {
 184         struct pf_fragment      *frag;
 185         int                      goal;
 186
 187         goal = pf_nfrents * 9 / 10;
 188         DPFPRINTF(("trying to free > %d frents\n",
 189             pf_nfrents - goal));
 190         while (goal < pf_nfrents) {
 191                 frag = TAILQ_LAST(&pf_fragqueue, pf_fragqueue);
 192                 if (frag == NULL)
 193                         break;
 194                 pf_free_fragment(frag);
 195         }
 196
 197
 198         goal = pf_ncache * 9 / 10;
 199         DPFPRINTF(("trying to free > %d cache entries\n",
 200             pf_ncache - goal));
 201         while (goal < pf_ncache) {
 202                 frag = TAILQ_LAST(&pf_cachequeue, pf_cachequeue);
 203                 if (frag == NULL)
 204                         break;
 205                 pf_free_fragment(frag);
 206         }
 207 }
 208
 209 /* Frees the fragments and all associated entries */
 210
 211 void
 212 pf_free_fragment(struct pf_fragment *frag)
 213 {
 214         struct pf_frent         *frent;
 215         struct pf_frcache       *frcache;
 216
 217         /* Free all fragments */
 218         if (BUFFER_FRAGMENTS(frag)) {
 219                 for (frent = LIST_FIRST(&frag->fr_queue); frent;
 220                     frent = LIST_FIRST(&frag->fr_queue)) {
 221                         LIST_REMOVE(frent, fr_next);
 222
 223                         m_freem(frent->fr_m);
 224                         pool_put(&pf_frent_pl, frent);
 225                         pf_nfrents--;
 226                 }
 227         } else {
 228                 for (frcache = LIST_FIRST(&frag->fr_cache); frcache;
 229                     frcache = LIST_FIRST(&frag->fr_cache)) {
 230                         LIST_REMOVE(frcache, fr_next);
 231
 232                         KASSERT((LIST_EMPTY(&frag->fr_cache) ||
 233                             LIST_FIRST(&frag->fr_cache)->fr_off >
 234                             frcache->fr_end),
 235                             ("! (LIST_EMPTY() || LIST_FIRST()->fr_off >"
 236                              " frcache->fr_end): %s", __func__));
 237
 238                         pool_put(&pf_cent_pl, frcache);
 239                         pf_ncache--;
 240                 }
 241         }
 242
 243         pf_remove_fragment(frag);
 244 }
 245
 246 void
 247 pf_ip2key(struct pf_fragment *key, struct ip *ip)
 248 {
 249         key->fr_p = ip->ip_p;
 250         key->fr_id = ip->ip_id;
 251         key->fr_src.s_addr = ip->ip_src.s_addr;
 252         key->fr_dst.s_addr = ip->ip_dst.s_addr;
 253 }
 254
 255 struct pf_fragment *
 256 pf_find_fragment(struct ip *ip, struct pf_frag_tree *tree)
 257 {
 258         struct pf_fragment       key;
 259         struct pf_fragment      *frag;
 260
 261         pf_ip2key(&key, ip);
 262
 263         frag = RB_FIND(pf_frag_tree, tree, &key);
 264         if (frag != NULL) {
 265                 /* XXX Are we sure we want to update the timeout? */
 266                 frag->fr_timeout = time_second;
 267                 if (BUFFER_FRAGMENTS(frag)) {
 268                         TAILQ_REMOVE(&pf_fragqueue, frag, frag_next);
 269                         TAILQ_INSERT_HEAD(&pf_fragqueue, frag, frag_next);
 270                 } else {
 271                         TAILQ_REMOVE(&pf_cachequeue, frag, frag_next);
 272                         TAILQ_INSERT_HEAD(&pf_cachequeue, frag, frag_next);
 273                 }
 274         }
 275
 276         return (frag);
 277 }
 278
 279 /* Removes a fragment from the fragment queue and frees the fragment */
 280
 281 void
 282 pf_remove_fragment(struct pf_fragment *frag)
 283 {
 284         if (BUFFER_FRAGMENTS(frag)) {
 285                 RB_REMOVE(pf_frag_tree, &pf_frag_tree, frag);
 286                 TAILQ_REMOVE(&pf_fragqueue, frag, frag_next);
 287                 pool_put(&pf_frag_pl, frag);
 288         } else {
 289                 RB_REMOVE(pf_frag_tree, &pf_cache_tree, frag);
 290                 TAILQ_REMOVE(&pf_cachequeue, frag, frag_next);
 291                 pool_put(&pf_cache_pl, frag);
 292         }
 293 }
 294
 295 #define FR_IP_OFF(fr)   (((fr)->fr_ip->ip_off & IP_OFFMASK) << 3)
 296 struct mbuf *
 297 pf_reassemble(struct mbuf **m0, struct pf_fragment **frag,
 298     struct pf_frent *frent, int mff)
 299 {
 300         struct mbuf     *m = *m0, *m2;
 301         struct pf_frent *frea, *next;
 302         struct pf_frent *frep = NULL;
 303         struct ip       *ip = frent->fr_ip;
 304         int              hlen = ip->ip_hl << 2;
 305         u_int16_t        off = (ip->ip_off & IP_OFFMASK) << 3;
 306         u_int16_t        ip_len = ip->ip_len - ip->ip_hl * 4;
 307         u_int16_t        max = ip_len + off;
 308
 309         KASSERT((*frag == NULL || BUFFER_FRAGMENTS(*frag)),
 310             ("! (*frag == NULL || BUFFER_FRAGMENTS(*frag)): %s", __func__));
 311
 312         /* Strip off ip header */
 313         m->m_data += hlen;
 314         m->m_len -= hlen;
 315
 316         /* Create a new reassembly queue for this packet */
 317         if (*frag == NULL) {
 318                 *frag = pool_get(&pf_frag_pl, PR_NOWAIT);
 319                 if (*frag == NULL) {
 320                         pf_flush_fragments();
 321                         *frag = pool_get(&pf_frag_pl, PR_NOWAIT);
 322                         if (*frag == NULL)
 323                                 goto drop_fragment;
 324                 }
 325
 326                 (*frag)->fr_flags = 0;
 327                 (*frag)->fr_max = 0;
 328                 (*frag)->fr_src = frent->fr_ip->ip_src;
 329                 (*frag)->fr_dst = frent->fr_ip->ip_dst;
 330                 (*frag)->fr_p = frent->fr_ip->ip_p;
 331                 (*frag)->fr_id = frent->fr_ip->ip_id;
 332                 (*frag)->fr_timeout = time_second;
 333                 LIST_INIT(&(*frag)->fr_queue);
 334
 335                 RB_INSERT(pf_frag_tree, &pf_frag_tree, *frag);
 336                 TAILQ_INSERT_HEAD(&pf_fragqueue, *frag, frag_next);
 337
 338                 /* We do not have a previous fragment */
 339                 frep = NULL;
 340                 goto insert;
 341         }
 342
 343         /*
 344          * Find a fragment after the current one:
 345          *  - off contains the real shifted offset.
 346          */
 347         LIST_FOREACH(frea, &(*frag)->fr_queue, fr_next) {
 348                 if (FR_IP_OFF(frea) > off)
 349                         break;
 350                 frep = frea;
 351         }
 352
 353         KASSERT((frep != NULL || frea != NULL),
 354             ("!(frep != NULL || frea != NULL): %s", __func__));
 355
 356         if (frep != NULL &&
 357             FR_IP_OFF(frep) + frep->fr_ip->ip_len - frep->fr_ip->ip_hl *
 358             4 > off)
 359         {
 360                 u_int16_t       precut;
 361
 362                 precut = FR_IP_OFF(frep) + frep->fr_ip->ip_len -
 363                     frep->fr_ip->ip_hl * 4 - off;
 364                 if (precut >= ip_len)
 365                         goto drop_fragment;
 366                 m_adj(frent->fr_m, precut);
 367                 DPFPRINTF(("overlap -%d\n", precut));
 368                 /* Enforce 8 byte boundaries */
 369                 ip->ip_off = ip->ip_off + (precut >> 3);
 370                 off = (ip->ip_off & IP_OFFMASK) << 3;
 371                 ip_len -= precut;
 372                 ip->ip_len = ip_len;
 373         }
 374
 375         for (; frea != NULL && ip_len + off > FR_IP_OFF(frea);
 376             frea = next)
 377         {
 378                 u_int16_t       aftercut;
 379
 380                 aftercut = ip_len + off - FR_IP_OFF(frea);
 381                 DPFPRINTF(("adjust overlap %d\n", aftercut));
 382                 if (aftercut < frea->fr_ip->ip_len - frea->fr_ip->ip_hl
 383                     * 4)
 384                 {
 385                         frea->fr_ip->ip_len =
 386                             frea->fr_ip->ip_len - aftercut;
 387                         frea->fr_ip->ip_off = frea->fr_ip->ip_off +
 388                             (aftercut >> 3);
 389                         m_adj(frea->fr_m, aftercut);
 390                         break;
 391                 }
 392
 393                 /* This fragment is completely overlapped, loose it */
 394                 next = LIST_NEXT(frea, fr_next);
 395                 m_freem(frea->fr_m);
 396                 LIST_REMOVE(frea, fr_next);
 397                 pool_put(&pf_frent_pl, frea);
 398                 pf_nfrents--;
 399         }
 400
 401  insert:
 402         /* Update maximum data size */
 403         if ((*frag)->fr_max < max)
 404                 (*frag)->fr_max = max;
 405         /* This is the last segment */
 406         if (!mff)
 407                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
 408
 409         if (frep == NULL)
 410                 LIST_INSERT_HEAD(&(*frag)->fr_queue, frent, fr_next);
 411         else
 412                 LIST_INSERT_AFTER(frep, frent, fr_next);
 413
 414         /* Check if we are completely reassembled */
 415         if (!((*frag)->fr_flags & PFFRAG_SEENLAST))
 416                 return (NULL);
 417
 418         /* Check if we have all the data */
 419         off = 0;
 420         for (frep = LIST_FIRST(&(*frag)->fr_queue); frep; frep = next) {
 421                 next = LIST_NEXT(frep, fr_next);
 422
 423                 off += frep->fr_ip->ip_len - frep->fr_ip->ip_hl * 4;
 424                 if (off < (*frag)->fr_max &&
 425                     (next == NULL || FR_IP_OFF(next) != off))
 426                 {
 427                         DPFPRINTF(("missing fragment at %d, next %d, max %d\n",
 428                             off, next == NULL ? -1 : FR_IP_OFF(next),
 429                             (*frag)->fr_max));
 430                         return (NULL);
 431                 }
 432         }
 433         DPFPRINTF(("%d < %d?\n", off, (*frag)->fr_max));
 434         if (off < (*frag)->fr_max)
 435                 return (NULL);
 436
 437         /* We have all the data */
 438         frent = LIST_FIRST(&(*frag)->fr_queue);
 439         KASSERT((frent != NULL), ("frent == NULL: %s", __func__));
 440         if ((frent->fr_ip->ip_hl << 2) + off > IP_MAXPACKET) {
 441                 DPFPRINTF(("drop: too big: %d\n", off));
 442                 pf_free_fragment(*frag);
 443                 *frag = NULL;
 444                 return (NULL);
 445         }
 446         next = LIST_NEXT(frent, fr_next);
 447
 448         /* Magic from ip_input */
 449         ip = frent->fr_ip;
 450         m = frent->fr_m;
 451         m2 = m->m_next;
 452         m->m_next = NULL;
 453         m_cat(m, m2);
 454         pool_put(&pf_frent_pl, frent);
 455         pf_nfrents--;
 456         for (frent = next; frent != NULL; frent = next) {
 457                 next = LIST_NEXT(frent, fr_next);
 458
 459                 m2 = frent->fr_m;
 460                 pool_put(&pf_frent_pl, frent);
 461                 pf_nfrents--;
 462                 m->m_pkthdr.csum_flags &= m2->m_pkthdr.csum_flags;
 463                 m->m_pkthdr.csum_data += m2->m_pkthdr.csum_data;
 464                 m_cat(m, m2);
 465         }
 466
 467         /*
 468          * Note: this 1's complement optimization with <= 65535 fragments.
 469          *
 470          * Handle 1's complement carry for the 16 bit result.  This can
 471          * result in another carry which must also be handled.
 472          */
 473         m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) +
 474                                 (m->m_pkthdr.csum_data >> 16);
 475         if (m->m_pkthdr.csum_data > 0xFFFF)
 476                 m->m_pkthdr.csum_data -= 0xFFFF;
 477
 478
 479         ip->ip_src = (*frag)->fr_src;
 480         ip->ip_dst = (*frag)->fr_dst;
 481
 482         /* Remove from fragment queue */
 483         pf_remove_fragment(*frag);
 484         *frag = NULL;
 485
 486         hlen = ip->ip_hl << 2;
 487         ip->ip_len = off + hlen;
 488         m->m_len += hlen;
 489         m->m_data -= hlen;
 490
 491         /* some debugging cruft by sklower, below, will go away soon */
 492         /* XXX this should be done elsewhere */
 493         if (m->m_flags & M_PKTHDR) {
 494                 int plen = 0;
 495                 for (m2 = m; m2; m2 = m2->m_next)
 496                         plen += m2->m_len;
 497                 m->m_pkthdr.len = plen;
 498         }
 499
 500         DPFPRINTF(("complete: %p(%d)\n", m, ip->ip_len));
 501         return (m);
 502
 503  drop_fragment:
 504         /* Oops - fail safe - drop packet */
 505         pool_put(&pf_frent_pl, frent);
 506         pf_nfrents--;
 507         m_freem(m);
 508         return (NULL);
 509 }
 510
 511 struct mbuf *
 512 pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff,
 513     int drop, int *nomem)
 514 {
 515         struct mbuf             *m = *m0;
 516         struct pf_frcache       *frp, *fra, *cur = NULL;
 517         int                      ip_len = h->ip_len - (h->ip_hl << 2);
 518         u_int16_t                off = h->ip_off << 3;
 519         u_int16_t                max = ip_len + off;
 520         int                      hosed = 0;
 521
 522         KASSERT((*frag == NULL || !BUFFER_FRAGMENTS(*frag)),
 523             ("!(*frag == NULL || !BUFFER_FRAGMENTS(*frag)): %s", __func__));
 524
 525         /* Create a new range queue for this packet */
 526         if (*frag == NULL) {
 527                 *frag = pool_get(&pf_cache_pl, PR_NOWAIT);
 528                 if (*frag == NULL) {
 529                         pf_flush_fragments();
 530                         *frag = pool_get(&pf_cache_pl, PR_NOWAIT);
 531                         if (*frag == NULL)
 532                                 goto no_mem;
 533                 }
 534
 535                 /* Get an entry for the queue */
 536                 cur = pool_get(&pf_cent_pl, PR_NOWAIT);
 537                 if (cur == NULL) {
 538                         pool_put(&pf_cache_pl, *frag);
 539                         *frag = NULL;
 540                         goto no_mem;
 541                 }
 542                 pf_ncache++;
 543
 544                 (*frag)->fr_flags = PFFRAG_NOBUFFER;
 545                 (*frag)->fr_max = 0;
 546                 (*frag)->fr_src = h->ip_src;
 547                 (*frag)->fr_dst = h->ip_dst;
 548                 (*frag)->fr_p = h->ip_p;
 549                 (*frag)->fr_id = h->ip_id;
 550                 (*frag)->fr_timeout = time_second;
 551
 552                 cur->fr_off = off;
 553                 cur->fr_end = max;
 554                 LIST_INIT(&(*frag)->fr_cache);
 555                 LIST_INSERT_HEAD(&(*frag)->fr_cache, cur, fr_next);
 556
 557                 RB_INSERT(pf_frag_tree, &pf_cache_tree, *frag);
 558                 TAILQ_INSERT_HEAD(&pf_cachequeue, *frag, frag_next);
 559
 560                 DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max));
 561
 562                 goto pass;
 563         }
 564
 565         /*
 566          * Find a fragment after the current one:
 567          *  - off contains the real shifted offset.
 568          */
 569         frp = NULL;
 570         LIST_FOREACH(fra, &(*frag)->fr_cache, fr_next) {
 571                 if (fra->fr_off > off)
 572                         break;
 573                 frp = fra;
 574         }
 575
 576         KASSERT((frp != NULL || fra != NULL),
 577             ("!(frp != NULL || fra != NULL): %s", __func__));
 578
 579         if (frp != NULL) {
 580                 int     precut;
 581
 582                 precut = frp->fr_end - off;
 583                 if (precut >= ip_len) {
 584                         /* Fragment is entirely a duplicate */
 585                         DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n",
 586                             h->ip_id, frp->fr_off, frp->fr_end, off, max));
 587                         goto drop_fragment;
 588                 }
 589                 if (precut == 0) {
 590                         /* They are adjacent.  Fixup cache entry */
 591                         DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n",
 592                             h->ip_id, frp->fr_off, frp->fr_end, off, max));
 593                         frp->fr_end = max;
 594                 } else if (precut > 0) {
 595                         /* The first part of this payload overlaps with a
 596                          * fragment that has already been passed.
 597                          * Need to trim off the first part of the payload.
 598                          * But to do so easily, we need to create another
 599                          * mbuf to throw the original header into.
 600                          */
 601
 602                         DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n",
 603                             h->ip_id, precut, frp->fr_off, frp->fr_end, off,
 604                             max));
 605
 606                         off += precut;
 607                         max -= precut;
 608                         /* Update the previous frag to encompass this one */
 609                         frp->fr_end = max;
 610
 611                         if (!drop) {
 612                                 /* XXX Optimization opportunity
 613                                  * This is a very heavy way to trim the payload.
 614                                  * we could do it much faster by diddling mbuf
 615                                  * internals but that would be even less legible
 616                                  * than this mbuf magic.  For my next trick,
 617                                  * I'll pull a rabbit out of my laptop.
 618                                  */
 619                                 *m0 = m_dup(m, MB_DONTWAIT);
 620                                 /* From KAME Project : We have missed this! */
 621                                 m_adj(*m0, (h->ip_hl << 2) -
 622                                     (*m0)->m_pkthdr.len);
 623                                 if (*m0 == NULL)
 624                                         goto no_mem;
 625                                 KASSERT(((*m0)->m_next == NULL),
 626                                     ("(*m0)->m_next != NULL: %s",
 627                                     __func__));
 628                                 m_adj(m, precut + (h->ip_hl << 2));
 629                                 m_cat(*m0, m);
 630                                 m = *m0;
 631                                 if (m->m_flags & M_PKTHDR) {
 632                                         int plen = 0;
 633                                         struct mbuf *t;
 634                                         for (t = m; t; t = t->m_next)
 635                                                 plen += t->m_len;
 636                                         m->m_pkthdr.len = plen;
 637                                 }
 638
 639
 640                                 h = mtod(m, struct ip *);
 641
 642                                 KASSERT(((int)m->m_len ==
 643                                     h->ip_len - precut),
 644                                     ("m->m_len != h->ip_len - precut: %s",
 645                                     __func__));
 646                                 h->ip_off = h->ip_off +
 647                                     (precut >> 3);
 648                                 h->ip_len = h->ip_len - precut;
 649                         } else {
 650                                 hosed++;
 651                         }
 652                 } else {
 653                         /* There is a gap between fragments */
 654
 655                         DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n",
 656                             h->ip_id, -precut, frp->fr_off, frp->fr_end, off,
 657                             max));
 658
 659                         cur = pool_get(&pf_cent_pl, PR_NOWAIT);
 660                         if (cur == NULL)
 661                                 goto no_mem;
 662                         pf_ncache++;
 663
 664                         cur->fr_off = off;
 665                         cur->fr_end = max;
 666                         LIST_INSERT_AFTER(frp, cur, fr_next);
 667                 }
 668         }
 669
 670         if (fra != NULL) {
 671                 int     aftercut;
 672                 int     merge = 0;
 673
 674                 aftercut = max - fra->fr_off;
 675                 if (aftercut == 0) {
 676                         /* Adjacent fragments */
 677                         DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n",
 678                             h->ip_id, off, max, fra->fr_off, fra->fr_end));
 679                         fra->fr_off = off;
 680                         merge = 1;
 681                 } else if (aftercut > 0) {
 682                         /* Need to chop off the tail of this fragment */
 683                         DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n",
 684                             h->ip_id, aftercut, off, max, fra->fr_off,
 685                             fra->fr_end));
 686                         fra->fr_off = off;
 687                         max -= aftercut;
 688
 689                         merge = 1;
 690
 691                         if (!drop) {
 692                                 m_adj(m, -aftercut);
 693                                 if (m->m_flags & M_PKTHDR) {
 694                                         int plen = 0;
 695                                         struct mbuf *t;
 696                                         for (t = m; t; t = t->m_next)
 697                                                 plen += t->m_len;
 698                                         m->m_pkthdr.len = plen;
 699                                 }
 700                                 h = mtod(m, struct ip *);
 701                                 KASSERT(((int)m->m_len == h->ip_len - aftercut),
 702                                     ("m->m_len != h->ip_len - aftercut: %s",
 703                                     __func__));
 704                                 h->ip_len = h->ip_len - aftercut;
 705                         } else {
 706                                 hosed++;
 707                         }
 708                 } else if (frp == NULL) {
 709                         /* There is a gap between fragments */
 710                         DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n",
 711                             h->ip_id, -aftercut, off, max, fra->fr_off,
 712                             fra->fr_end));
 713
 714                         cur = pool_get(&pf_cent_pl, PR_NOWAIT);
 715                         if (cur == NULL)
 716                                 goto no_mem;
 717                         pf_ncache++;
 718
 719                         cur->fr_off = off;
 720                         cur->fr_end = max;
 721                         LIST_INSERT_BEFORE(fra, cur, fr_next);
 722                 }
 723
 724
 725                 /* Need to glue together two separate fragment descriptors */
 726                 if (merge) {
 727                         if (cur && fra->fr_off <= cur->fr_end) {
 728                                 /* Need to merge in a previous 'cur' */
 729                                 DPFPRINTF(("fragcache[%d]: adjacent(merge "
 730                                     "%d-%d) %d-%d (%d-%d)\n",
 731                                     h->ip_id, cur->fr_off, cur->fr_end, off,
 732                                     max, fra->fr_off, fra->fr_end));
 733                                 fra->fr_off = cur->fr_off;
 734                                 LIST_REMOVE(cur, fr_next);
 735                                 pool_put(&pf_cent_pl, cur);
 736                                 pf_ncache--;
 737                                 cur = NULL;
 738
 739                         } else if (frp && fra->fr_off <= frp->fr_end) {
 740                                 /* Need to merge in a modified 'frp' */
 741                                 KASSERT((cur == NULL), ("cur != NULL: %s",
 742                                     __func__));
 743                                 DPFPRINTF(("fragcache[%d]: adjacent(merge "
 744                                     "%d-%d) %d-%d (%d-%d)\n",
 745                                     h->ip_id, frp->fr_off, frp->fr_end, off,
 746                                     max, fra->fr_off, fra->fr_end));
 747                                 fra->fr_off = frp->fr_off;
 748                                 LIST_REMOVE(frp, fr_next);
 749                                 pool_put(&pf_cent_pl, frp);
 750                                 pf_ncache--;
 751                                 frp = NULL;
 752
 753                         }
 754                 }
 755         }
 756
 757         if (hosed) {
 758                 /*
 759                  * We must keep tracking the overall fragment even when
 760                  * we're going to drop it anyway so that we know when to
 761                  * free the overall descriptor.  Thus we drop the frag late.
 762                  */
 763                 goto drop_fragment;
 764         }
 765
 766
 767  pass:
 768         /* Update maximum data size */
 769         if ((*frag)->fr_max < max)
 770                 (*frag)->fr_max = max;
 771
 772         /* This is the last segment */
 773         if (!mff)
 774                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
 775
 776         /* Check if we are completely reassembled */
 777         if (((*frag)->fr_flags & PFFRAG_SEENLAST) &&
 778             LIST_FIRST(&(*frag)->fr_cache)->fr_off == 0 &&
 779             LIST_FIRST(&(*frag)->fr_cache)->fr_end == (*frag)->fr_max) {
 780                 /* Remove from fragment queue */
 781                 DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id,
 782                     (*frag)->fr_max));
 783                 pf_free_fragment(*frag);
 784                 *frag = NULL;
 785         }
 786
 787         return (m);
 788
 789  no_mem:
 790         *nomem = 1;
 791
 792         /* Still need to pay attention to !IP_MF */
 793         if (!mff && *frag != NULL)
 794                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
 795
 796         m_freem(m);
 797         return (NULL);
 798
 799  drop_fragment:
 800
 801         /* Still need to pay attention to !IP_MF */
 802         if (!mff && *frag != NULL)
 803                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
 804
 805         if (drop) {
 806                 /* This fragment has been deemed bad.  Don't reass */
 807                 if (((*frag)->fr_flags & PFFRAG_DROP) == 0)
 808                         DPFPRINTF(("fragcache[%d]: dropping overall fragment\n",
 809                             h->ip_id));
 810                 (*frag)->fr_flags |= PFFRAG_DROP;
 811         }
 812
 813         m_freem(m);
 814         return (NULL);
 815 }
 816
 817 int
 818 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason)
 819 {
 820         struct mbuf             *m = *m0;
 821         struct pf_rule          *r;
 822         struct pf_frent         *frent;
 823         struct pf_fragment      *frag = NULL;
 824         struct ip               *h = mtod(m, struct ip *);
 825         int                      mff = (h->ip_off & IP_MF);
 826         int                      hlen = h->ip_hl << 2;
 827         u_int16_t                fragoff = (h->ip_off & IP_OFFMASK) << 3;
 828         u_int16_t                max;
 829         int                      ip_len;
 830         int                      ip_off;
 831
 832         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
 833         while (r != NULL) {
 834                 r->evaluations++;
 835                 if (r->kif != NULL &&
 836                     (r->kif != kif && r->kif != kif->pfik_parent) == !r->ifnot)
 837                         r = r->skip[PF_SKIP_IFP].ptr;
 838                 else if (r->direction && r->direction != dir)
 839                         r = r->skip[PF_SKIP_DIR].ptr;
 840                 else if (r->af && r->af != AF_INET)
 841                         r = r->skip[PF_SKIP_AF].ptr;
 842                 else if (r->proto && r->proto != h->ip_p)
 843                         r = r->skip[PF_SKIP_PROTO].ptr;
 844                 else if (PF_MISMATCHAW(&r->src.addr,
 845                     (struct pf_addr *)&h->ip_src.s_addr, AF_INET, r->src.not))
 846                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
 847                 else if (PF_MISMATCHAW(&r->dst.addr,
 848                     (struct pf_addr *)&h->ip_dst.s_addr, AF_INET, r->dst.not))
 849                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
 850                 else
 851                         break;
 852         }
 853
 854         if (r == NULL)
 855                 return (PF_PASS);
 856         else
 857                 r->packets++;
 858
 859         /* Check for illegal packets */
 860         if (hlen < (int)sizeof(struct ip))
 861                 goto drop;
 862
 863         if (hlen > h->ip_len)
 864                 goto drop;
 865
 866         /* Clear IP_DF if the rule uses the no-df option */
 867         if (r->rule_flag & PFRULE_NODF)
 868                 h->ip_off &= ~IP_DF;
 869
 870         /* We will need other tests here */
 871         if (!fragoff && !mff)
 872                 goto no_fragment;
 873
 874         /* We're dealing with a fragment now. Don't allow fragments
 875          * with IP_DF to enter the cache. If the flag was cleared by
 876          * no-df above, fine. Otherwise drop it.
 877          */
 878         if (h->ip_off & IP_DF) {
 879                 DPFPRINTF(("IP_DF\n"));
 880                 goto bad;
 881         }
 882
 883         ip_len = h->ip_len - hlen;
 884         ip_off = (h->ip_off & IP_OFFMASK) << 3;
 885
 886         /* All fragments are 8 byte aligned */
 887         if (mff && (ip_len & 0x7)) {
 888                 DPFPRINTF(("mff and %d\n", ip_len));
 889                 goto bad;
 890         }
 891
 892         /* Respect maximum length */
 893         if (fragoff + ip_len > IP_MAXPACKET) {
 894                 DPFPRINTF(("max packet %d\n", fragoff + ip_len));
 895                 goto bad;
 896         }
 897         max = fragoff + ip_len;
 898
 899         if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) {
 900                 /* Fully buffer all of the fragments */
 901
 902                 frag = pf_find_fragment(h, &pf_frag_tree);
 903
 904                 /* Check if we saw the last fragment already */
 905                 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
 906                     max > frag->fr_max)
 907                         goto bad;
 908
 909                 /* Get an entry for the fragment queue */
 910                 frent = pool_get(&pf_frent_pl, PR_NOWAIT);
 911                 if (frent == NULL) {
 912                         REASON_SET(reason, PFRES_MEMORY);
 913                         return (PF_DROP);
 914                 }
 915                 pf_nfrents++;
 916                 frent->fr_ip = h;
 917                 frent->fr_m = m;
 918
 919                 /* Might return a completely reassembled mbuf, or NULL */
 920                 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
 921                 *m0 = m = pf_reassemble(m0, &frag, frent, mff);
 922
 923                 if (m == NULL)
 924                         return (PF_DROP);
 925
 926                 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
 927                         goto drop;
 928
 929                 h = mtod(m, struct ip *);
 930         } else {
 931                 /* non-buffering fragment cache (drops or masks overlaps) */
 932                 int     nomem = 0;
 933
 934                 if (dir == PF_OUT) {
 935                         if (m->m_pkthdr.fw_flags & PF_MBUF_FRAGCACHE) {
 936                                 /* Already passed the fragment cache in the
 937                                  * input direction.  If we continued, it would
 938                                  * appear to be a dup and would be dropped.
 939                                  */
 940                                 goto fragment_pass;
 941                         }
 942                 }
 943
 944                 frag = pf_find_fragment(h, &pf_cache_tree);
 945
 946                 /* Check if we saw the last fragment already */
 947                 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
 948                     max > frag->fr_max) {
 949                         if (r->rule_flag & PFRULE_FRAGDROP)
 950                                 frag->fr_flags |= PFFRAG_DROP;
 951                         goto bad;
 952                 }
 953
 954                 *m0 = m = pf_fragcache(m0, h, &frag, mff,
 955                     (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem);
 956                 if (m == NULL) {
 957                         if (nomem)
 958                                 goto no_mem;
 959                         goto drop;
 960                 }
 961
 962                 if (dir == PF_IN)
 963                         m->m_pkthdr.fw_flags |= PF_MBUF_FRAGCACHE;
 964
 965                 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
 966                         goto drop;
 967                 goto fragment_pass;
 968         }
 969
 970  no_fragment:
 971         /* At this point, only IP_DF is allowed in ip_off */
 972         h->ip_off &= IP_DF;
 973
 974         /* Enforce a minimum ttl, may cause endless packet loops */
 975         if (r->min_ttl && h->ip_ttl < r->min_ttl)
 976                 h->ip_ttl = r->min_ttl;
 977
 978         if (r->rule_flag & PFRULE_RANDOMID) {
 979 #ifdef RANDOM_IP_ID
 980                 h->ip_id = ip_randomid();
 981 #else
 982                 h->ip_id = htons(ip_id++);
 983 #endif
 984         }
 985
 986         return (PF_PASS);
 987
 988  fragment_pass:
 989         /* Enforce a minimum ttl, may cause endless packet loops */
 990         if (r->min_ttl && h->ip_ttl < r->min_ttl)
 991                 h->ip_ttl = r->min_ttl;
 992
 993         return (PF_PASS);
 994
 995  no_mem:
 996         REASON_SET(reason, PFRES_MEMORY);
 997         if (r != NULL && r->log)
 998                 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL);
 999         return (PF_DROP);
1000
1001  drop:
1002         REASON_SET(reason, PFRES_NORM);
1003         if (r != NULL && r->log)
1004                 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL);
1005         return (PF_DROP);
1006
1007  bad:
1008         DPFPRINTF(("dropping bad fragment\n"));
1009
1010         /* Free associated fragments */
1011         if (frag != NULL)
1012                 pf_free_fragment(frag);
1013
1014         REASON_SET(reason, PFRES_FRAG);
1015         if (r != NULL && r->log)
1016                 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL);
1017
1018         return (PF_DROP);
1019 }
1020
1021 #ifdef INET6
1022 int
1023 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif,
1024     u_short *reason)
1025 {
1026         struct mbuf             *m = *m0;
1027         struct pf_rule          *r;
1028         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
1029         int                      off;
1030         struct ip6_ext           ext;
1031         struct ip6_opt           opt;
1032         struct ip6_opt_jumbo     jumbo;
1033         struct ip6_frag          frag;
1034         u_int32_t                jumbolen = 0, plen;
1035         u_int16_t                fragoff = 0;
1036         int                      optend;
1037         int                      ooff;
1038         u_int8_t                 proto;
1039         int                      terminal;
1040
1041         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1042         while (r != NULL) {
1043                 r->evaluations++;
1044                 if (r->kif != NULL &&
1045                     (r->kif != kif && r->kif != kif->pfik_parent) == !r->ifnot)
1046                         r = r->skip[PF_SKIP_IFP].ptr;
1047                 else if (r->direction && r->direction != dir)
1048                         r = r->skip[PF_SKIP_DIR].ptr;
1049                 else if (r->af && r->af != AF_INET6)
1050                         r = r->skip[PF_SKIP_AF].ptr;
1051 #if 0 /* header chain! */
1052                 else if (r->proto && r->proto != h->ip6_nxt)
1053                         r = r->skip[PF_SKIP_PROTO].ptr;
1054 #endif
1055                 else if (PF_MISMATCHAW(&r->src.addr,
1056                     (struct pf_addr *)&h->ip6_src, AF_INET6, r->src.not))
1057                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1058                 else if (PF_MISMATCHAW(&r->dst.addr,
1059                     (struct pf_addr *)&h->ip6_dst, AF_INET6, r->dst.not))
1060                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1061                 else
1062                         break;
1063         }
1064
1065         if (r == NULL)
1066                 return (PF_PASS);
1067         else
1068                 r->packets++;
1069
1070         /* Check for illegal packets */
1071         if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len)
1072                 goto drop;
1073
1074         off = sizeof(struct ip6_hdr);
1075         proto = h->ip6_nxt;
1076         terminal = 0;
1077         do {
1078                 switch (proto) {
1079                 case IPPROTO_FRAGMENT:
1080                         goto fragment;
1081                         break;
1082                 case IPPROTO_AH:
1083                 case IPPROTO_ROUTING:
1084                 case IPPROTO_DSTOPTS:
1085                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1086                             NULL, AF_INET6))
1087                                 goto shortpkt;
1088                         if (proto == IPPROTO_AH)
1089                                 off += (ext.ip6e_len + 2) * 4;
1090                         else
1091                                 off += (ext.ip6e_len + 1) * 8;
1092                         proto = ext.ip6e_nxt;
1093                         break;
1094                 case IPPROTO_HOPOPTS:
1095                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1096                             NULL, AF_INET6))
1097                                 goto shortpkt;
1098                         optend = off + (ext.ip6e_len + 1) * 8;
1099                         ooff = off + sizeof(ext);
1100                         do {
1101                                 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type,
1102                                     sizeof(opt.ip6o_type), NULL, NULL,
1103                                     AF_INET6))
1104                                         goto shortpkt;
1105                                 if (opt.ip6o_type == IP6OPT_PAD1) {
1106                                         ooff++;
1107                                         continue;
1108                                 }
1109                                 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt),
1110                                     NULL, NULL, AF_INET6))
1111                                         goto shortpkt;
1112                                 if (ooff + sizeof(opt) + opt.ip6o_len > optend)
1113                                         goto drop;
1114                                 switch (opt.ip6o_type) {
1115                                 case IP6OPT_JUMBO:
1116                                         if (h->ip6_plen != 0)
1117                                                 goto drop;
1118                                         if (!pf_pull_hdr(m, ooff, &jumbo,
1119                                             sizeof(jumbo), NULL, NULL,
1120                                             AF_INET6))
1121                                                 goto shortpkt;
1122                                         memcpy(&jumbolen, jumbo.ip6oj_jumbo_len,
1123                                             sizeof(jumbolen));
1124                                         jumbolen = ntohl(jumbolen);
1125                                         if (jumbolen <= IPV6_MAXPACKET)
1126                                                 goto drop;
1127                                         if (sizeof(struct ip6_hdr) + jumbolen !=
1128                                             m->m_pkthdr.len)
1129                                                 goto drop;
1130                                         break;
1131                                 default:
1132                                         break;
1133                                 }
1134                                 ooff += sizeof(opt) + opt.ip6o_len;
1135                         } while (ooff < optend);
1136
1137                         off = optend;
1138                         proto = ext.ip6e_nxt;
1139                         break;
1140                 default:
1141                         terminal = 1;
1142                         break;
1143                 }
1144         } while (!terminal);
1145
1146         /* jumbo payload option must be present, or plen > 0 */
1147         if (ntohs(h->ip6_plen) == 0)
1148                 plen = jumbolen;
1149         else
1150                 plen = ntohs(h->ip6_plen);
1151         if (plen == 0)
1152                 goto drop;
1153         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1154                 goto shortpkt;
1155
1156         /* Enforce a minimum ttl, may cause endless packet loops */
1157         if (r->min_ttl && h->ip6_hlim < r->min_ttl)
1158                 h->ip6_hlim = r->min_ttl;
1159
1160         return (PF_PASS);
1161
1162  fragment:
1163         if (ntohs(h->ip6_plen) == 0 || jumbolen)
1164                 goto drop;
1165         plen = ntohs(h->ip6_plen);
1166
1167         if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6))
1168                 goto shortpkt;
1169         fragoff = ntohs(frag.ip6f_offlg & IP6F_OFF_MASK);
1170         if (fragoff + (plen - off - sizeof(frag)) > IPV6_MAXPACKET)
1171                 goto badfrag;
1172
1173         /* do something about it */
1174         return (PF_PASS);
1175
1176  shortpkt:
1177         REASON_SET(reason, PFRES_SHORT);
1178         if (r != NULL && r->log)
1179                 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL);
1180         return (PF_DROP);
1181
1182  drop:
1183         REASON_SET(reason, PFRES_NORM);
1184         if (r != NULL && r->log)
1185                 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL);
1186         return (PF_DROP);
1187
1188  badfrag:
1189         REASON_SET(reason, PFRES_FRAG);
1190         if (r != NULL && r->log)
1191                 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL);
1192         return (PF_DROP);
1193 }
1194 #endif
1195
1196 int
1197 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff,
1198     int off, void *h, struct pf_pdesc *pd)
1199 {
1200         struct pf_rule  *r, *rm = NULL;
1201         struct tcphdr   *th = pd->hdr.tcp;
1202         int              rewrite = 0;
1203         u_short          reason;
1204         u_int8_t         flags;
1205         sa_family_t      af = pd->af;
1206
1207         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1208         while (r != NULL) {
1209                 r->evaluations++;
1210                 if (r->kif != NULL &&
1211                     (r->kif != kif && r->kif != kif->pfik_parent) == !r->ifnot)
1212                         r = r->skip[PF_SKIP_IFP].ptr;
1213                 else if (r->direction && r->direction != dir)
1214                         r = r->skip[PF_SKIP_DIR].ptr;
1215                 else if (r->af && r->af != af)
1216                         r = r->skip[PF_SKIP_AF].ptr;
1217                 else if (r->proto && r->proto != pd->proto)
1218                         r = r->skip[PF_SKIP_PROTO].ptr;
1219                 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, r->src.not))
1220                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1221                 else if (r->src.port_op && !pf_match_port(r->src.port_op,
1222                             r->src.port[0], r->src.port[1], th->th_sport))
1223                         r = r->skip[PF_SKIP_SRC_PORT].ptr;
1224                 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, r->dst.not))
1225                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1226                 else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
1227                             r->dst.port[0], r->dst.port[1], th->th_dport))
1228                         r = r->skip[PF_SKIP_DST_PORT].ptr;
1229                 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match(
1230                             pf_osfp_fingerprint(pd, m, off, th),
1231                             r->os_fingerprint))
1232                         r = TAILQ_NEXT(r, entries);
1233                 else {
1234                         rm = r;
1235                         break;
1236                 }
1237         }
1238
1239         if (rm == NULL)
1240                 return (PF_PASS);
1241         else
1242                 r->packets++;
1243
1244         if (rm->rule_flag & PFRULE_REASSEMBLE_TCP)
1245                 pd->flags |= PFDESC_TCP_NORM;
1246
1247         flags = th->th_flags;
1248         if (flags & TH_SYN) {
1249                 /* Illegal packet */
1250                 if (flags & TH_RST)
1251                         goto tcp_drop;
1252
1253                 if (flags & TH_FIN)
1254                         flags &= ~TH_FIN;
1255         } else {
1256                 /* Illegal packet */
1257                 if (!(flags & (TH_ACK|TH_RST)))
1258                         goto tcp_drop;
1259         }
1260
1261         if (!(flags & TH_ACK)) {
1262                 /* These flags are only valid if ACK is set */
1263                 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG))
1264                         goto tcp_drop;
1265         }
1266
1267         /* Check for illegal header length */
1268         if (th->th_off < (sizeof(struct tcphdr) >> 2))
1269                 goto tcp_drop;
1270
1271         /* If flags changed, or reserved data set, then adjust */
1272         if (flags != th->th_flags || th->th_x2 != 0) {
1273                 u_int16_t       ov, nv;
1274
1275                 ov = *(u_int16_t *)(&th->th_ack + 1);
1276                 th->th_flags = flags;
1277                 th->th_x2 = 0;
1278                 nv = *(u_int16_t *)(&th->th_ack + 1);
1279
1280                 th->th_sum = pf_cksum_fixup(th->th_sum, ov, nv);
1281                 rewrite = 1;
1282         }
1283
1284         /* Remove urgent pointer, if TH_URG is not set */
1285         if (!(flags & TH_URG) && th->th_urp) {
1286                 th->th_sum = pf_cksum_fixup(th->th_sum, th->th_urp, 0);
1287                 th->th_urp = 0;
1288                 rewrite = 1;
1289         }
1290
1291         /* Process options */
1292         if (r->max_mss && pf_normalize_tcpopt(r, m, th, off))
1293                 rewrite = 1;
1294
1295         /* copy back packet headers if we sanitized */
1296         if (rewrite)
1297                 m_copyback(m, off, sizeof(*th), (caddr_t)th);
1298
1299         return (PF_PASS);
1300
1301  tcp_drop:
1302         REASON_SET(&reason, PFRES_NORM);
1303         if (rm != NULL && r->log)
1304                 PFLOG_PACKET(kif, h, m, AF_INET, dir, reason, r, NULL, NULL);
1305         return (PF_DROP);
1306 }
1307
1308 int
1309 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd,
1310     struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst)
1311 {
1312         u_int8_t hdr[60];
1313         u_int8_t *opt;
1314
1315         KASSERT((src->scrub == NULL),
1316             ("pf_normalize_tcp_init: src->scrub != NULL"));
1317
1318         src->scrub = pool_get(&pf_state_scrub_pl, PR_NOWAIT);
1319         if (src->scrub == NULL)
1320                 return (1);
1321         bzero(src->scrub, sizeof(*src->scrub));
1322
1323         switch (pd->af) {
1324 #ifdef INET
1325         case AF_INET: {
1326                 struct ip *h = mtod(m, struct ip *);
1327                 src->scrub->pfss_ttl = h->ip_ttl;
1328                 break;
1329         }
1330 #endif /* INET */
1331 #ifdef INET6
1332         case AF_INET6: {
1333                 struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1334                 src->scrub->pfss_ttl = h->ip6_hlim;
1335                 break;
1336         }
1337 #endif /* INET6 */
1338         }
1339
1340
1341         /*
1342          * All normalizations below are only begun if we see the start of
1343          * the connections.  They must all set an enabled bit in pfss_flags
1344          */
1345         if ((th->th_flags & TH_SYN) == 0)
1346                 return (0);
1347
1348
1349         if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub &&
1350             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1351                 /* Diddle with TCP options */
1352                 int hlen;
1353                 opt = hdr + sizeof(struct tcphdr);
1354                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1355                 while (hlen >= TCPOLEN_TIMESTAMP) {
1356                         switch (*opt) {
1357                         case TCPOPT_EOL:        /* FALLTHROUGH */
1358                         case TCPOPT_NOP:
1359                                 opt++;
1360                                 hlen--;
1361                                 break;
1362                         case TCPOPT_TIMESTAMP:
1363                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1364                                         src->scrub->pfss_flags |=
1365                                             PFSS_TIMESTAMP;
1366                                         src->scrub->pfss_ts_mod = karc4random();
1367                                 }
1368                                 /* FALLTHROUGH */
1369                         default:
1370                                 hlen -= MAX(opt[1], 2);
1371                                 opt += MAX(opt[1], 2);
1372                                 break;
1373                         }
1374                 }
1375         }
1376
1377         return (0);
1378 }
1379
1380 void
1381 pf_normalize_tcp_cleanup(struct pf_state *state)
1382 {
1383         if (state->src.scrub)
1384                 pool_put(&pf_state_scrub_pl, state->src.scrub);
1385         if (state->dst.scrub)
1386                 pool_put(&pf_state_scrub_pl, state->dst.scrub);
1387
1388         /* Someday... flush the TCP segment reassembly descriptors. */
1389 }
1390
1391 int
1392 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd,
1393     u_short *reason, struct tcphdr *th, struct pf_state_peer *src,
1394     struct pf_state_peer *dst, int *writeback)
1395 {
1396         u_int8_t hdr[60];
1397         u_int8_t *opt;
1398         int copyback = 0;
1399
1400         KASSERT((src->scrub || dst->scrub),
1401             ("pf_normalize_tcp_statefull: src->scrub && dst->scrub!"));
1402
1403         /*
1404          * Enforce the minimum TTL seen for this connection.  Negate a common
1405          * technique to evade an intrusion detection system and confuse
1406          * firewall state code.
1407          */
1408         switch (pd->af) {
1409 #ifdef INET
1410         case AF_INET: {
1411                 if (src->scrub) {
1412                         struct ip *h = mtod(m, struct ip *);
1413                         if (h->ip_ttl > src->scrub->pfss_ttl)
1414                                 src->scrub->pfss_ttl = h->ip_ttl;
1415                         h->ip_ttl = src->scrub->pfss_ttl;
1416                 }
1417                 break;
1418         }
1419 #endif /* INET */
1420 #ifdef INET6
1421         case AF_INET6: {
1422                 if (src->scrub) {
1423                         struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1424                         if (h->ip6_hlim > src->scrub->pfss_ttl)
1425                                 src->scrub->pfss_ttl = h->ip6_hlim;
1426                         h->ip6_hlim = src->scrub->pfss_ttl;
1427                 }
1428                 break;
1429         }
1430 #endif /* INET6 */
1431         }
1432
1433         if (th->th_off > (sizeof(struct tcphdr) >> 2) &&
1434             ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) ||
1435             (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) &&
1436             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1437                 /* Diddle with TCP options */
1438                 int hlen;
1439                 opt = hdr + sizeof(struct tcphdr);
1440                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1441                 while (hlen >= TCPOLEN_TIMESTAMP) {
1442                         switch (*opt) {
1443                         case TCPOPT_EOL:        /* FALLTHROUGH */
1444                         case TCPOPT_NOP:
1445                                 opt++;
1446                                 hlen--;
1447                                 break;
1448                         case TCPOPT_TIMESTAMP:
1449                                 /* Modulate the timestamps.  Can be used for
1450                                  * NAT detection, OS uptime determination or
1451                                  * reboot detection.
1452                                  */
1453                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1454                                         u_int32_t ts_value;
1455                                         if (src->scrub &&
1456                                             (src->scrub->pfss_flags &
1457                                             PFSS_TIMESTAMP)) {
1458                                                 memcpy(&ts_value, &opt[2],
1459                                                     sizeof(u_int32_t));
1460                                                 ts_value = htonl(ntohl(ts_value)
1461                                                     + src->scrub->pfss_ts_mod);
1462                                                 pf_change_a(&opt[2],
1463                                                     &th->th_sum, ts_value, 0);
1464                                                 copyback = 1;
1465                                         }
1466
1467                                         /* Modulate TS reply iff valid (!0) */
1468                                         memcpy(&ts_value, &opt[6],
1469                                             sizeof(u_int32_t));
1470                                         if (ts_value && dst->scrub &&
1471                                             (dst->scrub->pfss_flags &
1472                                             PFSS_TIMESTAMP)) {
1473                                                 ts_value = htonl(ntohl(ts_value)
1474                                                     - dst->scrub->pfss_ts_mod);
1475                                                 pf_change_a(&opt[6],
1476                                                     &th->th_sum, ts_value, 0);
1477                                                 copyback = 1;
1478                                         }
1479                                 }
1480                                 /* FALLTHROUGH */
1481                         default:
1482                                 hlen -= MAX(opt[1], 2);
1483                                 opt += MAX(opt[1], 2);
1484                                 break;
1485                         }
1486                 }
1487                 if (copyback) {
1488                         /* Copyback the options, caller copys back header */
1489                         *writeback = 1;
1490                         m_copyback(m, off + sizeof(struct tcphdr),
1491                             (th->th_off << 2) - sizeof(struct tcphdr), hdr +
1492                             sizeof(struct tcphdr));
1493                 }
1494         }
1495
1496
1497         /* I have a dream....  TCP segment reassembly.... */
1498         return (0);
1499 }
1500
1501 int
1502 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th,
1503     int off)
1504 {
1505         u_int16_t       *mss;
1506         int              thoff;
1507         int              opt, cnt, optlen = 0;
1508         int              rewrite = 0;
1509         u_char          *optp;
1510
1511         thoff = th->th_off << 2;
1512         cnt = thoff - sizeof(struct tcphdr);
1513         optp = mtod(m, caddr_t) + off + sizeof(struct tcphdr);
1514
1515         for (; cnt > 0; cnt -= optlen, optp += optlen) {
1516                 opt = optp[0];
1517                 if (opt == TCPOPT_EOL)
1518                         break;
1519                 if (opt == TCPOPT_NOP)
1520                         optlen = 1;
1521                 else {
1522                         if (cnt < 2)
1523                                 break;
1524                         optlen = optp[1];
1525                         if (optlen < 2 || optlen > cnt)
1526                                 break;
1527                 }
1528                 switch (opt) {
1529                 case TCPOPT_MAXSEG:
1530                         mss = (u_int16_t *)(optp + 2);
1531                         if ((ntohs(*mss)) > r->max_mss) {
1532                                 th->th_sum = pf_cksum_fixup(th->th_sum,
1533                                     *mss, htons(r->max_mss));
1534                                 *mss = htons(r->max_mss);
1535                                 rewrite = 1;
1536                         }
1537                         break;
1538                 default:
1539                         break;
1540                 }
1541         }
1542
1543         return (rewrite);
1544 }