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 1.6 2006/09/03 17:31:55 dillon 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 /* IPv6 options: common part */
  73 struct ip6_opt {
  74         u_int8_t ip6o_type;
  75         u_int8_t ip6o_len;
  76 } __packed;
  77
  78 /* Jumbo Payload Option */
  79 struct ip6_opt_jumbo {
  80         u_int8_t ip6oj_type;
  81         u_int8_t ip6oj_len;
  82         u_int8_t ip6oj_jumbo_len[4];
  83 } __packed;
  84
  85 /* NSAP Address Option */
  86 struct ip6_opt_nsap {
  87         u_int8_t ip6on_type;
  88         u_int8_t ip6on_len;
  89         u_int8_t ip6on_src_nsap_len;
  90         u_int8_t ip6on_dst_nsap_len;
  91         /* followed by source NSAP */
  92         /* followed by destination NSAP */
  93 } __packed;
  94
  95 /* Tunnel Limit Option */
  96 struct ip6_opt_tunnel {
  97         u_int8_t ip6ot_type;
  98         u_int8_t ip6ot_len;
  99         u_int8_t ip6ot_encap_limit;
 100 } __packed;
 101
 102 /* Router Alert Option */
 103 struct ip6_opt_router {
 104         u_int8_t ip6or_type;
 105         u_int8_t ip6or_len;
 106         u_int8_t ip6or_value[2];
 107 } __packed;
 108 #endif /* INET6 */
 109
 110 #define PFFRAG_SEENLAST 0x0001          /* Seen the last fragment for this */
 111 #define PFFRAG_NOBUFFER 0x0002          /* Non-buffering fragment cache */
 112 #define PFFRAG_DROP     0x0004          /* Drop all fragments */
 113 #define BUFFER_FRAGMENTS(fr)    (!((fr)->fr_flags & PFFRAG_NOBUFFER))
 114
 115
 116 TAILQ_HEAD(pf_fragqueue, pf_fragment)   pf_fragqueue;
 117 TAILQ_HEAD(pf_cachequeue, pf_fragment)  pf_cachequeue;
 118
 119 static int              pf_frag_compare(struct pf_fragment *,
 120                                         struct pf_fragment *);
 121 RB_HEAD(pf_frag_tree, pf_fragment)      pf_frag_tree, pf_cache_tree;
 122 RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 123 RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 124
 125 /* Private prototypes */
 126 void                     pf_ip2key(struct pf_fragment *, struct ip *);
 127 void                     pf_remove_fragment(struct pf_fragment *);
 128 void                     pf_flush_fragments(void);
 129 void                     pf_free_fragment(struct pf_fragment *);
 130 struct pf_fragment      *pf_find_fragment(struct ip *, struct pf_frag_tree *);
 131 struct mbuf             *pf_reassemble(struct mbuf **, struct pf_fragment **,
 132                             struct pf_frent *, int);
 133 struct mbuf             *pf_fragcache(struct mbuf **, struct ip*,
 134                             struct pf_fragment **, int, int, int *);
 135 u_int16_t                pf_cksum_fixup(u_int16_t, u_int16_t, u_int16_t);
 136 int                      pf_normalize_tcpopt(struct pf_rule *, struct mbuf *,
 137                             struct tcphdr *, int);
 138
 139 #define DPFPRINTF(x)    if (pf_status.debug >= PF_DEBUG_MISC) \
 140                             { printf("%s: ", __func__); printf x ;}
 141
 142 /* Globals */
 143 vm_zone_t                pf_frent_pl, pf_frag_pl, pf_cache_pl, pf_cent_pl;
 144 vm_zone_t                pf_state_scrub_pl;
 145 int                      pf_nfrents, pf_ncache;
 146
 147 void
 148 pf_normalize_init(void)
 149 {
 150         /* XXX
 151         pool_sethiwat(&pf_frag_pl, PFFRAG_FRAG_HIWAT);
 152         pool_sethardlimit(&pf_frent_pl, PFFRAG_FRENT_HIWAT, NULL, 0);
 153         pool_sethardlimit(&pf_cache_pl, PFFRAG_FRCACHE_HIWAT, NULL, 0);
 154         pool_sethardlimit(&pf_cent_pl, PFFRAG_FRCENT_HIWAT, NULL, 0);
 155         */
 156
 157         TAILQ_INIT(&pf_fragqueue);
 158         TAILQ_INIT(&pf_cachequeue);
 159 }
 160
 161 static int
 162 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b)
 163 {
 164         int     diff;
 165
 166         if ((diff = a->fr_id - b->fr_id))
 167                 return (diff);
 168         else if ((diff = a->fr_p - b->fr_p))
 169                 return (diff);
 170         else if (a->fr_src.s_addr < b->fr_src.s_addr)
 171                 return (-1);
 172         else if (a->fr_src.s_addr > b->fr_src.s_addr)
 173                 return (1);
 174         else if (a->fr_dst.s_addr < b->fr_dst.s_addr)
 175                 return (-1);
 176         else if (a->fr_dst.s_addr > b->fr_dst.s_addr)
 177                 return (1);
 178         return (0);
 179 }
 180
 181 void
 182 pf_purge_expired_fragments(void)
 183 {
 184         struct pf_fragment      *frag;
 185         u_int32_t                expire = time_second -
 186                                     pf_default_rule.timeout[PFTM_FRAG];
 187
 188         while ((frag = TAILQ_LAST(&pf_fragqueue, pf_fragqueue)) != NULL) {
 189                 KASSERT((BUFFER_FRAGMENTS(frag)),
 190                         ("BUFFER_FRAGMENTS(frag) == 0: %s", __func__));
 191                 if (frag->fr_timeout > expire)
 192                         break;
 193
 194                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 195                 pf_free_fragment(frag);
 196         }
 197
 198         while ((frag = TAILQ_LAST(&pf_cachequeue, pf_cachequeue)) != NULL) {
 199                 KASSERT((!BUFFER_FRAGMENTS(frag)),
 200                         ("BUFFER_FRAGMENTS(frag) != 0: %s", __func__));
 201                 if (frag->fr_timeout > expire)
 202                         break;
 203
 204                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 205                 pf_free_fragment(frag);
 206                 KASSERT((TAILQ_EMPTY(&pf_cachequeue) ||
 207                     TAILQ_LAST(&pf_cachequeue, pf_cachequeue) != frag),
 208                     ("!(TAILQ_EMPTY() || TAILQ_LAST() == farg): %s",
 209                     __func__));
 210         }
 211 }
 212
 213 /*
 214  * Try to flush old fragments to make space for new ones
 215  */
 216
 217 void
 218 pf_flush_fragments(void)
 219 {
 220         struct pf_fragment      *frag;
 221         int                      goal;
 222
 223         goal = pf_nfrents * 9 / 10;
 224         DPFPRINTF(("trying to free > %d frents\n",
 225             pf_nfrents - goal));
 226         while (goal < pf_nfrents) {
 227                 frag = TAILQ_LAST(&pf_fragqueue, pf_fragqueue);
 228                 if (frag == NULL)
 229                         break;
 230                 pf_free_fragment(frag);
 231         }
 232
 233
 234         goal = pf_ncache * 9 / 10;
 235         DPFPRINTF(("trying to free > %d cache entries\n",
 236             pf_ncache - goal));
 237         while (goal < pf_ncache) {
 238                 frag = TAILQ_LAST(&pf_cachequeue, pf_cachequeue);
 239                 if (frag == NULL)
 240                         break;
 241                 pf_free_fragment(frag);
 242         }
 243 }
 244
 245 /* Frees the fragments and all associated entries */
 246
 247 void
 248 pf_free_fragment(struct pf_fragment *frag)
 249 {
 250         struct pf_frent         *frent;
 251         struct pf_frcache       *frcache;
 252
 253         /* Free all fragments */
 254         if (BUFFER_FRAGMENTS(frag)) {
 255                 for (frent = LIST_FIRST(&frag->fr_queue); frent;
 256                     frent = LIST_FIRST(&frag->fr_queue)) {
 257                         LIST_REMOVE(frent, fr_next);
 258
 259                         m_freem(frent->fr_m);
 260                         pool_put(&pf_frent_pl, frent);
 261                         pf_nfrents--;
 262                 }
 263         } else {
 264                 for (frcache = LIST_FIRST(&frag->fr_cache); frcache;
 265                     frcache = LIST_FIRST(&frag->fr_cache)) {
 266                         LIST_REMOVE(frcache, fr_next);
 267
 268                         KASSERT((LIST_EMPTY(&frag->fr_cache) ||
 269                             LIST_FIRST(&frag->fr_cache)->fr_off >
 270                             frcache->fr_end),
 271                             ("! (LIST_EMPTY() || LIST_FIRST()->fr_off >"
 272                              " frcache->fr_end): %s", __func__));
 273
 274                         pool_put(&pf_cent_pl, frcache);
 275                         pf_ncache--;
 276                 }
 277         }
 278
 279         pf_remove_fragment(frag);
 280 }
 281
 282 void
 283 pf_ip2key(struct pf_fragment *key, struct ip *ip)
 284 {
 285         key->fr_p = ip->ip_p;
 286         key->fr_id = ip->ip_id;
 287         key->fr_src.s_addr = ip->ip_src.s_addr;
 288         key->fr_dst.s_addr = ip->ip_dst.s_addr;
 289 }
 290
 291 struct pf_fragment *
 292 pf_find_fragment(struct ip *ip, struct pf_frag_tree *tree)
 293 {
 294         struct pf_fragment       key;
 295         struct pf_fragment      *frag;
 296
 297         pf_ip2key(&key, ip);
 298
 299         frag = RB_FIND(pf_frag_tree, tree, &key);
 300         if (frag != NULL) {
 301                 /* XXX Are we sure we want to update the timeout? */
 302                 frag->fr_timeout = time_second;
 303                 if (BUFFER_FRAGMENTS(frag)) {
 304                         TAILQ_REMOVE(&pf_fragqueue, frag, frag_next);
 305                         TAILQ_INSERT_HEAD(&pf_fragqueue, frag, frag_next);
 306                 } else {
 307                         TAILQ_REMOVE(&pf_cachequeue, frag, frag_next);
 308                         TAILQ_INSERT_HEAD(&pf_cachequeue, frag, frag_next);
 309                 }
 310         }
 311
 312         return (frag);
 313 }
 314
 315 /* Removes a fragment from the fragment queue and frees the fragment */
 316
 317 void
 318 pf_remove_fragment(struct pf_fragment *frag)
 319 {
 320         if (BUFFER_FRAGMENTS(frag)) {
 321                 RB_REMOVE(pf_frag_tree, &pf_frag_tree, frag);
 322                 TAILQ_REMOVE(&pf_fragqueue, frag, frag_next);
 323                 pool_put(&pf_frag_pl, frag);
 324         } else {
 325                 RB_REMOVE(pf_frag_tree, &pf_cache_tree, frag);
 326                 TAILQ_REMOVE(&pf_cachequeue, frag, frag_next);
 327                 pool_put(&pf_cache_pl, frag);
 328         }
 329 }
 330
 331 #define FR_IP_OFF(fr)   (((fr)->fr_ip->ip_off & IP_OFFMASK) << 3)
 332 struct mbuf *
 333 pf_reassemble(struct mbuf **m0, struct pf_fragment **frag,
 334     struct pf_frent *frent, int mff)
 335 {
 336         struct mbuf     *m = *m0, *m2;
 337         struct pf_frent *frea, *next;
 338         struct pf_frent *frep = NULL;
 339         struct ip       *ip = frent->fr_ip;
 340         int              hlen = ip->ip_hl << 2;
 341         u_int16_t        off = (ip->ip_off & IP_OFFMASK) << 3;
 342         u_int16_t        ip_len = ip->ip_len - ip->ip_hl * 4;
 343         u_int16_t        max = ip_len + off;
 344
 345         KASSERT((*frag == NULL || BUFFER_FRAGMENTS(*frag)),
 346             ("! (*frag == NULL || BUFFER_FRAGMENTS(*frag)): %s", __func__));
 347
 348         /* Strip off ip header */
 349         m->m_data += hlen;
 350         m->m_len -= hlen;
 351
 352         /* Create a new reassembly queue for this packet */
 353         if (*frag == NULL) {
 354                 *frag = pool_get(&pf_frag_pl, PR_NOWAIT);
 355                 if (*frag == NULL) {
 356                         pf_flush_fragments();
 357                         *frag = pool_get(&pf_frag_pl, PR_NOWAIT);
 358                         if (*frag == NULL)
 359                                 goto drop_fragment;
 360                 }
 361
 362                 (*frag)->fr_flags = 0;
 363                 (*frag)->fr_max = 0;
 364                 (*frag)->fr_src = frent->fr_ip->ip_src;
 365                 (*frag)->fr_dst = frent->fr_ip->ip_dst;
 366                 (*frag)->fr_p = frent->fr_ip->ip_p;
 367                 (*frag)->fr_id = frent->fr_ip->ip_id;
 368                 (*frag)->fr_timeout = time_second;
 369                 LIST_INIT(&(*frag)->fr_queue);
 370
 371                 RB_INSERT(pf_frag_tree, &pf_frag_tree, *frag);
 372                 TAILQ_INSERT_HEAD(&pf_fragqueue, *frag, frag_next);
 373
 374                 /* We do not have a previous fragment */
 375                 frep = NULL;
 376                 goto insert;
 377         }
 378
 379         /*
 380          * Find a fragment after the current one:
 381          *  - off contains the real shifted offset.
 382          */
 383         LIST_FOREACH(frea, &(*frag)->fr_queue, fr_next) {
 384                 if (FR_IP_OFF(frea) > off)
 385                         break;
 386                 frep = frea;
 387         }
 388
 389         KASSERT((frep != NULL || frea != NULL),
 390             ("!(frep != NULL || frea != NULL): %s", __func__));
 391
 392         if (frep != NULL &&
 393             FR_IP_OFF(frep) + frep->fr_ip->ip_len - frep->fr_ip->ip_hl *
 394             4 > off)
 395         {
 396                 u_int16_t       precut;
 397
 398                 precut = FR_IP_OFF(frep) + frep->fr_ip->ip_len -
 399                     frep->fr_ip->ip_hl * 4 - off;
 400                 if (precut >= ip_len)
 401                         goto drop_fragment;
 402                 m_adj(frent->fr_m, precut);
 403                 DPFPRINTF(("overlap -%d\n", precut));
 404                 /* Enforce 8 byte boundaries */
 405                 ip->ip_off = ip->ip_off + (precut >> 3);
 406                 off = (ip->ip_off & IP_OFFMASK) << 3;
 407                 ip_len -= precut;
 408                 ip->ip_len = ip_len;
 409         }
 410
 411         for (; frea != NULL && ip_len + off > FR_IP_OFF(frea);
 412             frea = next)
 413         {
 414                 u_int16_t       aftercut;
 415
 416                 aftercut = ip_len + off - FR_IP_OFF(frea);
 417                 DPFPRINTF(("adjust overlap %d\n", aftercut));
 418                 if (aftercut < frea->fr_ip->ip_len - frea->fr_ip->ip_hl
 419                     * 4)
 420                 {
 421                         frea->fr_ip->ip_len =
 422                             frea->fr_ip->ip_len - aftercut;
 423                         frea->fr_ip->ip_off = frea->fr_ip->ip_off +
 424                             (aftercut >> 3);
 425                         m_adj(frea->fr_m, aftercut);
 426                         break;
 427                 }
 428
 429                 /* This fragment is completely overlapped, loose it */
 430                 next = LIST_NEXT(frea, fr_next);
 431                 m_freem(frea->fr_m);
 432                 LIST_REMOVE(frea, fr_next);
 433                 pool_put(&pf_frent_pl, frea);
 434                 pf_nfrents--;
 435         }
 436
 437  insert:
 438         /* Update maximum data size */
 439         if ((*frag)->fr_max < max)
 440                 (*frag)->fr_max = max;
 441         /* This is the last segment */
 442         if (!mff)
 443                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
 444
 445         if (frep == NULL)
 446                 LIST_INSERT_HEAD(&(*frag)->fr_queue, frent, fr_next);
 447         else
 448                 LIST_INSERT_AFTER(frep, frent, fr_next);
 449
 450         /* Check if we are completely reassembled */
 451         if (!((*frag)->fr_flags & PFFRAG_SEENLAST))
 452                 return (NULL);
 453
 454         /* Check if we have all the data */
 455         off = 0;
 456         for (frep = LIST_FIRST(&(*frag)->fr_queue); frep; frep = next) {
 457                 next = LIST_NEXT(frep, fr_next);
 458
 459                 off += frep->fr_ip->ip_len - frep->fr_ip->ip_hl * 4;
 460                 if (off < (*frag)->fr_max &&
 461                     (next == NULL || FR_IP_OFF(next) != off))
 462                 {
 463                         DPFPRINTF(("missing fragment at %d, next %d, max %d\n",
 464                             off, next == NULL ? -1 : FR_IP_OFF(next),
 465                             (*frag)->fr_max));
 466                         return (NULL);
 467                 }
 468         }
 469         DPFPRINTF(("%d < %d?\n", off, (*frag)->fr_max));
 470         if (off < (*frag)->fr_max)
 471                 return (NULL);
 472
 473         /* We have all the data */
 474         frent = LIST_FIRST(&(*frag)->fr_queue);
 475         KASSERT((frent != NULL), ("frent == NULL: %s", __func__));
 476         if ((frent->fr_ip->ip_hl << 2) + off > IP_MAXPACKET) {
 477                 DPFPRINTF(("drop: too big: %d\n", off));
 478                 pf_free_fragment(*frag);
 479                 *frag = NULL;
 480                 return (NULL);
 481         }
 482         next = LIST_NEXT(frent, fr_next);
 483
 484         /* Magic from ip_input */
 485         ip = frent->fr_ip;
 486         m = frent->fr_m;
 487         m2 = m->m_next;
 488         m->m_next = NULL;
 489         m_cat(m, m2);
 490         pool_put(&pf_frent_pl, frent);
 491         pf_nfrents--;
 492         for (frent = next; frent != NULL; frent = next) {
 493                 next = LIST_NEXT(frent, fr_next);
 494
 495                 m2 = frent->fr_m;
 496                 pool_put(&pf_frent_pl, frent);
 497                 pf_nfrents--;
 498                 m_cat(m, m2);
 499         }
 500
 501         ip->ip_src = (*frag)->fr_src;
 502         ip->ip_dst = (*frag)->fr_dst;
 503
 504         /* Remove from fragment queue */
 505         pf_remove_fragment(*frag);
 506         *frag = NULL;
 507
 508         hlen = ip->ip_hl << 2;
 509         ip->ip_len = off + hlen;
 510         m->m_len += hlen;
 511         m->m_data -= hlen;
 512
 513         /* some debugging cruft by sklower, below, will go away soon */
 514         /* XXX this should be done elsewhere */
 515         if (m->m_flags & M_PKTHDR) {
 516                 int plen = 0;
 517                 for (m2 = m; m2; m2 = m2->m_next)
 518                         plen += m2->m_len;
 519                 m->m_pkthdr.len = plen;
 520         }
 521
 522         DPFPRINTF(("complete: %p(%d)\n", m, ip->ip_len));
 523         return (m);
 524
 525  drop_fragment:
 526         /* Oops - fail safe - drop packet */
 527         pool_put(&pf_frent_pl, frent);
 528         pf_nfrents--;
 529         m_freem(m);
 530         return (NULL);
 531 }
 532
 533 struct mbuf *
 534 pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff,
 535     int drop, int *nomem)
 536 {
 537         struct mbuf             *m = *m0;
 538         struct pf_frcache       *frp, *fra, *cur = NULL;
 539         int                      ip_len = h->ip_len - (h->ip_hl << 2);
 540         u_int16_t                off = h->ip_off << 3;
 541         u_int16_t                max = ip_len + off;
 542         int                      hosed = 0;
 543
 544         KASSERT((*frag == NULL || !BUFFER_FRAGMENTS(*frag)),
 545             ("!(*frag == NULL || !BUFFER_FRAGMENTS(*frag)): %s", __func__));
 546
 547         /* Create a new range queue for this packet */
 548         if (*frag == NULL) {
 549                 *frag = pool_get(&pf_cache_pl, PR_NOWAIT);
 550                 if (*frag == NULL) {
 551                         pf_flush_fragments();
 552                         *frag = pool_get(&pf_cache_pl, PR_NOWAIT);
 553                         if (*frag == NULL)
 554                                 goto no_mem;
 555                 }
 556
 557                 /* Get an entry for the queue */
 558                 cur = pool_get(&pf_cent_pl, PR_NOWAIT);
 559                 if (cur == NULL) {
 560                         pool_put(&pf_cache_pl, *frag);
 561                         *frag = NULL;
 562                         goto no_mem;
 563                 }
 564                 pf_ncache++;
 565
 566                 (*frag)->fr_flags = PFFRAG_NOBUFFER;
 567                 (*frag)->fr_max = 0;
 568                 (*frag)->fr_src = h->ip_src;
 569                 (*frag)->fr_dst = h->ip_dst;
 570                 (*frag)->fr_p = h->ip_p;
 571                 (*frag)->fr_id = h->ip_id;
 572                 (*frag)->fr_timeout = time_second;
 573
 574                 cur->fr_off = off;
 575                 cur->fr_end = max;
 576                 LIST_INIT(&(*frag)->fr_cache);
 577                 LIST_INSERT_HEAD(&(*frag)->fr_cache, cur, fr_next);
 578
 579                 RB_INSERT(pf_frag_tree, &pf_cache_tree, *frag);
 580                 TAILQ_INSERT_HEAD(&pf_cachequeue, *frag, frag_next);
 581
 582                 DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max));
 583
 584                 goto pass;
 585         }
 586
 587         /*
 588          * Find a fragment after the current one:
 589          *  - off contains the real shifted offset.
 590          */
 591         frp = NULL;
 592         LIST_FOREACH(fra, &(*frag)->fr_cache, fr_next) {
 593                 if (fra->fr_off > off)
 594                         break;
 595                 frp = fra;
 596         }
 597
 598         KASSERT((frp != NULL || fra != NULL),
 599             ("!(frp != NULL || fra != NULL): %s", __func__));
 600
 601         if (frp != NULL) {
 602                 int     precut;
 603
 604                 precut = frp->fr_end - off;
 605                 if (precut >= ip_len) {
 606                         /* Fragment is entirely a duplicate */
 607                         DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n",
 608                             h->ip_id, frp->fr_off, frp->fr_end, off, max));
 609                         goto drop_fragment;
 610                 }
 611                 if (precut == 0) {
 612                         /* They are adjacent.  Fixup cache entry */
 613                         DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n",
 614                             h->ip_id, frp->fr_off, frp->fr_end, off, max));
 615                         frp->fr_end = max;
 616                 } else if (precut > 0) {
 617                         /* The first part of this payload overlaps with a
 618                          * fragment that has already been passed.
 619                          * Need to trim off the first part of the payload.
 620                          * But to do so easily, we need to create another
 621                          * mbuf to throw the original header into.
 622                          */
 623
 624                         DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n",
 625                             h->ip_id, precut, frp->fr_off, frp->fr_end, off,
 626                             max));
 627
 628                         off += precut;
 629                         max -= precut;
 630                         /* Update the previous frag to encompass this one */
 631                         frp->fr_end = max;
 632
 633                         if (!drop) {
 634                                 /* XXX Optimization opportunity
 635                                  * This is a very heavy way to trim the payload.
 636                                  * we could do it much faster by diddling mbuf
 637                                  * internals but that would be even less legible
 638                                  * than this mbuf magic.  For my next trick,
 639                                  * I'll pull a rabbit out of my laptop.
 640                                  */
 641                                 *m0 = m_dup(m, MB_DONTWAIT);
 642                                 /* From KAME Project : We have missed this! */
 643                                 m_adj(*m0, (h->ip_hl << 2) -
 644                                     (*m0)->m_pkthdr.len);
 645                                 if (*m0 == NULL)
 646                                         goto no_mem;
 647                                 KASSERT(((*m0)->m_next == NULL),
 648                                     ("(*m0)->m_next != NULL: %s",
 649                                     __func__));
 650                                 m_adj(m, precut + (h->ip_hl << 2));
 651                                 m_cat(*m0, m);
 652                                 m = *m0;
 653                                 if (m->m_flags & M_PKTHDR) {
 654                                         int plen = 0;
 655                                         struct mbuf *t;
 656                                         for (t = m; t; t = t->m_next)
 657                                                 plen += t->m_len;
 658                                         m->m_pkthdr.len = plen;
 659                                 }
 660
 661
 662                                 h = mtod(m, struct ip *);
 663
 664                                 KASSERT(((int)m->m_len ==
 665                                     h->ip_len - precut),
 666                                     ("m->m_len != h->ip_len - precut: %s",
 667                                     __func__));
 668                                 h->ip_off = h->ip_off +
 669                                     (precut >> 3);
 670                                 h->ip_len = h->ip_len - precut;
 671                         } else {
 672                                 hosed++;
 673                         }
 674                 } else {
 675                         /* There is a gap between fragments */
 676
 677                         DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n",
 678                             h->ip_id, -precut, frp->fr_off, frp->fr_end, off,
 679                             max));
 680
 681                         cur = pool_get(&pf_cent_pl, PR_NOWAIT);
 682                         if (cur == NULL)
 683                                 goto no_mem;
 684                         pf_ncache++;
 685
 686                         cur->fr_off = off;
 687                         cur->fr_end = max;
 688                         LIST_INSERT_AFTER(frp, cur, fr_next);
 689                 }
 690         }
 691
 692         if (fra != NULL) {
 693                 int     aftercut;
 694                 int     merge = 0;
 695
 696                 aftercut = max - fra->fr_off;
 697                 if (aftercut == 0) {
 698                         /* Adjacent fragments */
 699                         DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n",
 700                             h->ip_id, off, max, fra->fr_off, fra->fr_end));
 701                         fra->fr_off = off;
 702                         merge = 1;
 703                 } else if (aftercut > 0) {
 704                         /* Need to chop off the tail of this fragment */
 705                         DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n",
 706                             h->ip_id, aftercut, off, max, fra->fr_off,
 707                             fra->fr_end));
 708                         fra->fr_off = off;
 709                         max -= aftercut;
 710
 711                         merge = 1;
 712
 713                         if (!drop) {
 714                                 m_adj(m, -aftercut);
 715                                 if (m->m_flags & M_PKTHDR) {
 716                                         int plen = 0;
 717                                         struct mbuf *t;
 718                                         for (t = m; t; t = t->m_next)
 719                                                 plen += t->m_len;
 720                                         m->m_pkthdr.len = plen;
 721                                 }
 722                                 h = mtod(m, struct ip *);
 723                                 KASSERT(((int)m->m_len == h->ip_len - aftercut),
 724                                     ("m->m_len != h->ip_len - aftercut: %s",
 725                                     __func__));
 726                                 h->ip_len = h->ip_len - aftercut;
 727                         } else {
 728                                 hosed++;
 729                         }
 730                 } else if (frp == NULL) {
 731                         /* There is a gap between fragments */
 732                         DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n",
 733                             h->ip_id, -aftercut, off, max, fra->fr_off,
 734                             fra->fr_end));
 735
 736                         cur = pool_get(&pf_cent_pl, PR_NOWAIT);
 737                         if (cur == NULL)
 738                                 goto no_mem;
 739                         pf_ncache++;
 740
 741                         cur->fr_off = off;
 742                         cur->fr_end = max;
 743                         LIST_INSERT_BEFORE(fra, cur, fr_next);
 744                 }
 745
 746
 747                 /* Need to glue together two separate fragment descriptors */
 748                 if (merge) {
 749                         if (cur && fra->fr_off <= cur->fr_end) {
 750                                 /* Need to merge in a previous 'cur' */
 751                                 DPFPRINTF(("fragcache[%d]: adjacent(merge "
 752                                     "%d-%d) %d-%d (%d-%d)\n",
 753                                     h->ip_id, cur->fr_off, cur->fr_end, off,
 754                                     max, fra->fr_off, fra->fr_end));
 755                                 fra->fr_off = cur->fr_off;
 756                                 LIST_REMOVE(cur, fr_next);
 757                                 pool_put(&pf_cent_pl, cur);
 758                                 pf_ncache--;
 759                                 cur = NULL;
 760
 761                         } else if (frp && fra->fr_off <= frp->fr_end) {
 762                                 /* Need to merge in a modified 'frp' */
 763                                 KASSERT((cur == NULL), ("cur != NULL: %s",
 764                                     __func__));
 765                                 DPFPRINTF(("fragcache[%d]: adjacent(merge "
 766                                     "%d-%d) %d-%d (%d-%d)\n",
 767                                     h->ip_id, frp->fr_off, frp->fr_end, off,
 768                                     max, fra->fr_off, fra->fr_end));
 769                                 fra->fr_off = frp->fr_off;
 770                                 LIST_REMOVE(frp, fr_next);
 771                                 pool_put(&pf_cent_pl, frp);
 772                                 pf_ncache--;
 773                                 frp = NULL;
 774
 775                         }
 776                 }
 777         }
 778
 779         if (hosed) {
 780                 /*
 781                  * We must keep tracking the overall fragment even when
 782                  * we're going to drop it anyway so that we know when to
 783                  * free the overall descriptor.  Thus we drop the frag late.
 784                  */
 785                 goto drop_fragment;
 786         }
 787
 788
 789  pass:
 790         /* Update maximum data size */
 791         if ((*frag)->fr_max < max)
 792                 (*frag)->fr_max = max;
 793
 794         /* This is the last segment */
 795         if (!mff)
 796                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
 797
 798         /* Check if we are completely reassembled */
 799         if (((*frag)->fr_flags & PFFRAG_SEENLAST) &&
 800             LIST_FIRST(&(*frag)->fr_cache)->fr_off == 0 &&
 801             LIST_FIRST(&(*frag)->fr_cache)->fr_end == (*frag)->fr_max) {
 802                 /* Remove from fragment queue */
 803                 DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id,
 804                     (*frag)->fr_max));
 805                 pf_free_fragment(*frag);
 806                 *frag = NULL;
 807         }
 808
 809         return (m);
 810
 811  no_mem:
 812         *nomem = 1;
 813
 814         /* Still need to pay attention to !IP_MF */
 815         if (!mff && *frag != NULL)
 816                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
 817
 818         m_freem(m);
 819         return (NULL);
 820
 821  drop_fragment:
 822
 823         /* Still need to pay attention to !IP_MF */
 824         if (!mff && *frag != NULL)
 825                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
 826
 827         if (drop) {
 828                 /* This fragment has been deemed bad.  Don't reass */
 829                 if (((*frag)->fr_flags & PFFRAG_DROP) == 0)
 830                         DPFPRINTF(("fragcache[%d]: dropping overall fragment\n",
 831                             h->ip_id));
 832                 (*frag)->fr_flags |= PFFRAG_DROP;
 833         }
 834
 835         m_freem(m);
 836         return (NULL);
 837 }
 838
 839 int
 840 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason)
 841 {
 842         struct mbuf             *m = *m0;
 843         struct pf_rule          *r;
 844         struct pf_frent         *frent;
 845         struct pf_fragment      *frag = NULL;
 846         struct ip               *h = mtod(m, struct ip *);
 847         int                      mff = (h->ip_off & IP_MF);
 848         int                      hlen = h->ip_hl << 2;
 849         u_int16_t                fragoff = (h->ip_off & IP_OFFMASK) << 3;
 850         u_int16_t                max;
 851         int                      ip_len;
 852         int                      ip_off;
 853
 854         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
 855         while (r != NULL) {
 856                 r->evaluations++;
 857                 if (r->kif != NULL &&
 858                     (r->kif != kif && r->kif != kif->pfik_parent) == !r->ifnot)
 859                         r = r->skip[PF_SKIP_IFP].ptr;
 860                 else if (r->direction && r->direction != dir)
 861                         r = r->skip[PF_SKIP_DIR].ptr;
 862                 else if (r->af && r->af != AF_INET)
 863                         r = r->skip[PF_SKIP_AF].ptr;
 864                 else if (r->proto && r->proto != h->ip_p)
 865                         r = r->skip[PF_SKIP_PROTO].ptr;
 866                 else if (PF_MISMATCHAW(&r->src.addr,
 867                     (struct pf_addr *)&h->ip_src.s_addr, AF_INET, r->src.not))
 868                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
 869                 else if (PF_MISMATCHAW(&r->dst.addr,
 870                     (struct pf_addr *)&h->ip_dst.s_addr, AF_INET, r->dst.not))
 871                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
 872                 else
 873                         break;
 874         }
 875
 876         if (r == NULL)
 877                 return (PF_PASS);
 878         else
 879                 r->packets++;
 880
 881         /* Check for illegal packets */
 882         if (hlen < (int)sizeof(struct ip))
 883                 goto drop;
 884
 885         if (hlen > h->ip_len)
 886                 goto drop;
 887
 888         /* Clear IP_DF if the rule uses the no-df option */
 889         if (r->rule_flag & PFRULE_NODF)
 890                 h->ip_off &= ~IP_DF;
 891
 892         /* We will need other tests here */
 893         if (!fragoff && !mff)
 894                 goto no_fragment;
 895
 896         /* We're dealing with a fragment now. Don't allow fragments
 897          * with IP_DF to enter the cache. If the flag was cleared by
 898          * no-df above, fine. Otherwise drop it.
 899          */
 900         if (h->ip_off & IP_DF) {
 901                 DPFPRINTF(("IP_DF\n"));
 902                 goto bad;
 903         }
 904
 905         ip_len = h->ip_len - hlen;
 906         ip_off = (h->ip_off & IP_OFFMASK) << 3;
 907
 908         /* All fragments are 8 byte aligned */
 909         if (mff && (ip_len & 0x7)) {
 910                 DPFPRINTF(("mff and %d\n", ip_len));
 911                 goto bad;
 912         }
 913
 914         /* Respect maximum length */
 915         if (fragoff + ip_len > IP_MAXPACKET) {
 916                 DPFPRINTF(("max packet %d\n", fragoff + ip_len));
 917                 goto bad;
 918         }
 919         max = fragoff + ip_len;
 920
 921         if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) {
 922                 /* Fully buffer all of the fragments */
 923
 924                 frag = pf_find_fragment(h, &pf_frag_tree);
 925
 926                 /* Check if we saw the last fragment already */
 927                 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
 928                     max > frag->fr_max)
 929                         goto bad;
 930
 931                 /* Get an entry for the fragment queue */
 932                 frent = pool_get(&pf_frent_pl, PR_NOWAIT);
 933                 if (frent == NULL) {
 934                         REASON_SET(reason, PFRES_MEMORY);
 935                         return (PF_DROP);
 936                 }
 937                 pf_nfrents++;
 938                 frent->fr_ip = h;
 939                 frent->fr_m = m;
 940
 941                 /* Might return a completely reassembled mbuf, or NULL */
 942                 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
 943                 *m0 = m = pf_reassemble(m0, &frag, frent, mff);
 944
 945                 if (m == NULL)
 946                         return (PF_DROP);
 947
 948                 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
 949                         goto drop;
 950
 951                 h = mtod(m, struct ip *);
 952         } else {
 953                 /* non-buffering fragment cache (drops or masks overlaps) */
 954                 int     nomem = 0;
 955
 956                 if (dir == PF_OUT) {
 957                         if (m->m_pkthdr.fw_flags & PF_MBUF_FRAGCACHE) {
 958                                 /* Already passed the fragment cache in the
 959                                  * input direction.  If we continued, it would
 960                                  * appear to be a dup and would be dropped.
 961                                  */
 962                                 goto fragment_pass;
 963                         }
 964                 }
 965
 966                 frag = pf_find_fragment(h, &pf_cache_tree);
 967
 968                 /* Check if we saw the last fragment already */
 969                 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
 970                     max > frag->fr_max) {
 971                         if (r->rule_flag & PFRULE_FRAGDROP)
 972                                 frag->fr_flags |= PFFRAG_DROP;
 973                         goto bad;
 974                 }
 975
 976                 *m0 = m = pf_fragcache(m0, h, &frag, mff,
 977                     (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem);
 978                 if (m == NULL) {
 979                         if (nomem)
 980                                 goto no_mem;
 981                         goto drop;
 982                 }
 983
 984                 if (dir == PF_IN)
 985                         m->m_pkthdr.fw_flags |= PF_MBUF_FRAGCACHE;
 986
 987                 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
 988                         goto drop;
 989                 goto fragment_pass;
 990         }
 991
 992  no_fragment:
 993         /* At this point, only IP_DF is allowed in ip_off */
 994         h->ip_off &= IP_DF;
 995
 996         /* Enforce a minimum ttl, may cause endless packet loops */
 997         if (r->min_ttl && h->ip_ttl < r->min_ttl)
 998                 h->ip_ttl = r->min_ttl;
 999
1000         if (r->rule_flag & PFRULE_RANDOMID) {
1001 #ifdef RANDOM_IP_ID
1002                 h->ip_id = ip_randomid();
1003 #else
1004                 h->ip_id = htons(ip_id++);
1005 #endif
1006         }
1007
1008         return (PF_PASS);
1009
1010  fragment_pass:
1011         /* Enforce a minimum ttl, may cause endless packet loops */
1012         if (r->min_ttl && h->ip_ttl < r->min_ttl)
1013                 h->ip_ttl = r->min_ttl;
1014
1015         return (PF_PASS);
1016
1017  no_mem:
1018         REASON_SET(reason, PFRES_MEMORY);
1019         if (r != NULL && r->log)
1020                 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL);
1021         return (PF_DROP);
1022
1023  drop:
1024         REASON_SET(reason, PFRES_NORM);
1025         if (r != NULL && r->log)
1026                 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL);
1027         return (PF_DROP);
1028
1029  bad:
1030         DPFPRINTF(("dropping bad fragment\n"));
1031
1032         /* Free associated fragments */
1033         if (frag != NULL)
1034                 pf_free_fragment(frag);
1035
1036         REASON_SET(reason, PFRES_FRAG);
1037         if (r != NULL && r->log)
1038                 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL);
1039
1040         return (PF_DROP);
1041 }
1042
1043 #ifdef INET6
1044 int
1045 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif,
1046     u_short *reason)
1047 {
1048         struct mbuf             *m = *m0;
1049         struct pf_rule          *r;
1050         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
1051         int                      off;
1052         struct ip6_ext           ext;
1053         struct ip6_opt           opt;
1054         struct ip6_opt_jumbo     jumbo;
1055         struct ip6_frag          frag;
1056         u_int32_t                jumbolen = 0, plen;
1057         u_int16_t                fragoff = 0;
1058         int                      optend;
1059         int                      ooff;
1060         u_int8_t                 proto;
1061         int                      terminal;
1062
1063         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1064         while (r != NULL) {
1065                 r->evaluations++;
1066                 if (r->kif != NULL &&
1067                     (r->kif != kif && r->kif != kif->pfik_parent) == !r->ifnot)
1068                         r = r->skip[PF_SKIP_IFP].ptr;
1069                 else if (r->direction && r->direction != dir)
1070                         r = r->skip[PF_SKIP_DIR].ptr;
1071                 else if (r->af && r->af != AF_INET6)
1072                         r = r->skip[PF_SKIP_AF].ptr;
1073 #if 0 /* header chain! */
1074                 else if (r->proto && r->proto != h->ip6_nxt)
1075                         r = r->skip[PF_SKIP_PROTO].ptr;
1076 #endif
1077                 else if (PF_MISMATCHAW(&r->src.addr,
1078                     (struct pf_addr *)&h->ip6_src, AF_INET6, r->src.not))
1079                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1080                 else if (PF_MISMATCHAW(&r->dst.addr,
1081                     (struct pf_addr *)&h->ip6_dst, AF_INET6, r->dst.not))
1082                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1083                 else
1084                         break;
1085         }
1086
1087         if (r == NULL)
1088                 return (PF_PASS);
1089         else
1090                 r->packets++;
1091
1092         /* Check for illegal packets */
1093         if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len)
1094                 goto drop;
1095
1096         off = sizeof(struct ip6_hdr);
1097         proto = h->ip6_nxt;
1098         terminal = 0;
1099         do {
1100                 switch (proto) {
1101                 case IPPROTO_FRAGMENT:
1102                         goto fragment;
1103                         break;
1104                 case IPPROTO_AH:
1105                 case IPPROTO_ROUTING:
1106                 case IPPROTO_DSTOPTS:
1107                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1108                             NULL, AF_INET6))
1109                                 goto shortpkt;
1110                         if (proto == IPPROTO_AH)
1111                                 off += (ext.ip6e_len + 2) * 4;
1112                         else
1113                                 off += (ext.ip6e_len + 1) * 8;
1114                         proto = ext.ip6e_nxt;
1115                         break;
1116                 case IPPROTO_HOPOPTS:
1117                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1118                             NULL, AF_INET6))
1119                                 goto shortpkt;
1120                         optend = off + (ext.ip6e_len + 1) * 8;
1121                         ooff = off + sizeof(ext);
1122                         do {
1123                                 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type,
1124                                     sizeof(opt.ip6o_type), NULL, NULL,
1125                                     AF_INET6))
1126                                         goto shortpkt;
1127                                 if (opt.ip6o_type == IP6OPT_PAD1) {
1128                                         ooff++;
1129                                         continue;
1130                                 }
1131                                 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt),
1132                                     NULL, NULL, AF_INET6))
1133                                         goto shortpkt;
1134                                 if (ooff + sizeof(opt) + opt.ip6o_len > optend)
1135                                         goto drop;
1136                                 switch (opt.ip6o_type) {
1137                                 case IP6OPT_JUMBO:
1138                                         if (h->ip6_plen != 0)
1139                                                 goto drop;
1140                                         if (!pf_pull_hdr(m, ooff, &jumbo,
1141                                             sizeof(jumbo), NULL, NULL,
1142                                             AF_INET6))
1143                                                 goto shortpkt;
1144                                         memcpy(&jumbolen, jumbo.ip6oj_jumbo_len,
1145                                             sizeof(jumbolen));
1146                                         jumbolen = ntohl(jumbolen);
1147                                         if (jumbolen <= IPV6_MAXPACKET)
1148                                                 goto drop;
1149                                         if (sizeof(struct ip6_hdr) + jumbolen !=
1150                                             m->m_pkthdr.len)
1151                                                 goto drop;
1152                                         break;
1153                                 default:
1154                                         break;
1155                                 }
1156                                 ooff += sizeof(opt) + opt.ip6o_len;
1157                         } while (ooff < optend);
1158
1159                         off = optend;
1160                         proto = ext.ip6e_nxt;
1161                         break;
1162                 default:
1163                         terminal = 1;
1164                         break;
1165                 }
1166         } while (!terminal);
1167
1168         /* jumbo payload option must be present, or plen > 0 */
1169         if (ntohs(h->ip6_plen) == 0)
1170                 plen = jumbolen;
1171         else
1172                 plen = ntohs(h->ip6_plen);
1173         if (plen == 0)
1174                 goto drop;
1175         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1176                 goto shortpkt;
1177
1178         /* Enforce a minimum ttl, may cause endless packet loops */
1179         if (r->min_ttl && h->ip6_hlim < r->min_ttl)
1180                 h->ip6_hlim = r->min_ttl;
1181
1182         return (PF_PASS);
1183
1184  fragment:
1185         if (ntohs(h->ip6_plen) == 0 || jumbolen)
1186                 goto drop;
1187         plen = ntohs(h->ip6_plen);
1188
1189         if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6))
1190                 goto shortpkt;
1191         fragoff = ntohs(frag.ip6f_offlg & IP6F_OFF_MASK);
1192         if (fragoff + (plen - off - sizeof(frag)) > IPV6_MAXPACKET)
1193                 goto badfrag;
1194
1195         /* do something about it */
1196         return (PF_PASS);
1197
1198  shortpkt:
1199         REASON_SET(reason, PFRES_SHORT);
1200         if (r != NULL && r->log)
1201                 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL);
1202         return (PF_DROP);
1203
1204  drop:
1205         REASON_SET(reason, PFRES_NORM);
1206         if (r != NULL && r->log)
1207                 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL);
1208         return (PF_DROP);
1209
1210  badfrag:
1211         REASON_SET(reason, PFRES_FRAG);
1212         if (r != NULL && r->log)
1213                 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL);
1214         return (PF_DROP);
1215 }
1216 #endif
1217
1218 int
1219 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff,
1220     int off, void *h, struct pf_pdesc *pd)
1221 {
1222         struct pf_rule  *r, *rm = NULL;
1223         struct tcphdr   *th = pd->hdr.tcp;
1224         int              rewrite = 0;
1225         u_short          reason;
1226         u_int8_t         flags;
1227         sa_family_t      af = pd->af;
1228
1229         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1230         while (r != NULL) {
1231                 r->evaluations++;
1232                 if (r->kif != NULL &&
1233                     (r->kif != kif && r->kif != kif->pfik_parent) == !r->ifnot)
1234                         r = r->skip[PF_SKIP_IFP].ptr;
1235                 else if (r->direction && r->direction != dir)
1236                         r = r->skip[PF_SKIP_DIR].ptr;
1237                 else if (r->af && r->af != af)
1238                         r = r->skip[PF_SKIP_AF].ptr;
1239                 else if (r->proto && r->proto != pd->proto)
1240                         r = r->skip[PF_SKIP_PROTO].ptr;
1241                 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af, r->src.not))
1242                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1243                 else if (r->src.port_op && !pf_match_port(r->src.port_op,
1244                             r->src.port[0], r->src.port[1], th->th_sport))
1245                         r = r->skip[PF_SKIP_SRC_PORT].ptr;
1246                 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af, r->dst.not))
1247                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1248                 else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
1249                             r->dst.port[0], r->dst.port[1], th->th_dport))
1250                         r = r->skip[PF_SKIP_DST_PORT].ptr;
1251                 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match(
1252                             pf_osfp_fingerprint(pd, m, off, th),
1253                             r->os_fingerprint))
1254                         r = TAILQ_NEXT(r, entries);
1255                 else {
1256                         rm = r;
1257                         break;
1258                 }
1259         }
1260
1261         if (rm == NULL)
1262                 return (PF_PASS);
1263         else
1264                 r->packets++;
1265
1266         if (rm->rule_flag & PFRULE_REASSEMBLE_TCP)
1267                 pd->flags |= PFDESC_TCP_NORM;
1268
1269         flags = th->th_flags;
1270         if (flags & TH_SYN) {
1271                 /* Illegal packet */
1272                 if (flags & TH_RST)
1273                         goto tcp_drop;
1274
1275                 if (flags & TH_FIN)
1276                         flags &= ~TH_FIN;
1277         } else {
1278                 /* Illegal packet */
1279                 if (!(flags & (TH_ACK|TH_RST)))
1280                         goto tcp_drop;
1281         }
1282
1283         if (!(flags & TH_ACK)) {
1284                 /* These flags are only valid if ACK is set */
1285                 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG))
1286                         goto tcp_drop;
1287         }
1288
1289         /* Check for illegal header length */
1290         if (th->th_off < (sizeof(struct tcphdr) >> 2))
1291                 goto tcp_drop;
1292
1293         /* If flags changed, or reserved data set, then adjust */
1294         if (flags != th->th_flags || th->th_x2 != 0) {
1295                 u_int16_t       ov, nv;
1296
1297                 ov = *(u_int16_t *)(&th->th_ack + 1);
1298                 th->th_flags = flags;
1299                 th->th_x2 = 0;
1300                 nv = *(u_int16_t *)(&th->th_ack + 1);
1301
1302                 th->th_sum = pf_cksum_fixup(th->th_sum, ov, nv);
1303                 rewrite = 1;
1304         }
1305
1306         /* Remove urgent pointer, if TH_URG is not set */
1307         if (!(flags & TH_URG) && th->th_urp) {
1308                 th->th_sum = pf_cksum_fixup(th->th_sum, th->th_urp, 0);
1309                 th->th_urp = 0;
1310                 rewrite = 1;
1311         }
1312
1313         /* Process options */
1314         if (r->max_mss && pf_normalize_tcpopt(r, m, th, off))
1315                 rewrite = 1;
1316
1317         /* copy back packet headers if we sanitized */
1318         if (rewrite)
1319                 m_copyback(m, off, sizeof(*th), (caddr_t)th);
1320
1321         return (PF_PASS);
1322
1323  tcp_drop:
1324         REASON_SET(&reason, PFRES_NORM);
1325         if (rm != NULL && r->log)
1326                 PFLOG_PACKET(kif, h, m, AF_INET, dir, reason, r, NULL, NULL);
1327         return (PF_DROP);
1328 }
1329
1330 int
1331 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd,
1332     struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst)
1333 {
1334         u_int8_t hdr[60];
1335         u_int8_t *opt;
1336
1337         KASSERT((src->scrub == NULL),
1338             ("pf_normalize_tcp_init: src->scrub != NULL"));
1339
1340         src->scrub = pool_get(&pf_state_scrub_pl, PR_NOWAIT);
1341         if (src->scrub == NULL)
1342                 return (1);
1343         bzero(src->scrub, sizeof(*src->scrub));
1344
1345         switch (pd->af) {
1346 #ifdef INET
1347         case AF_INET: {
1348                 struct ip *h = mtod(m, struct ip *);
1349                 src->scrub->pfss_ttl = h->ip_ttl;
1350                 break;
1351         }
1352 #endif /* INET */
1353 #ifdef INET6
1354         case AF_INET6: {
1355                 struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1356                 src->scrub->pfss_ttl = h->ip6_hlim;
1357                 break;
1358         }
1359 #endif /* INET6 */
1360         }
1361
1362
1363         /*
1364          * All normalizations below are only begun if we see the start of
1365          * the connections.  They must all set an enabled bit in pfss_flags
1366          */
1367         if ((th->th_flags & TH_SYN) == 0)
1368                 return (0);
1369
1370
1371         if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub &&
1372             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1373                 /* Diddle with TCP options */
1374                 int hlen;
1375                 opt = hdr + sizeof(struct tcphdr);
1376                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1377                 while (hlen >= TCPOLEN_TIMESTAMP) {
1378                         switch (*opt) {
1379                         case TCPOPT_EOL:        /* FALLTHROUGH */
1380                         case TCPOPT_NOP:
1381                                 opt++;
1382                                 hlen--;
1383                                 break;
1384                         case TCPOPT_TIMESTAMP:
1385                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1386                                         src->scrub->pfss_flags |=
1387                                             PFSS_TIMESTAMP;
1388                                         src->scrub->pfss_ts_mod = karc4random();
1389                                 }
1390                                 /* FALLTHROUGH */
1391                         default:
1392                                 hlen -= MAX(opt[1], 2);
1393                                 opt += MAX(opt[1], 2);
1394                                 break;
1395                         }
1396                 }
1397         }
1398
1399         return (0);
1400 }
1401
1402 void
1403 pf_normalize_tcp_cleanup(struct pf_state *state)
1404 {
1405         if (state->src.scrub)
1406                 pool_put(&pf_state_scrub_pl, state->src.scrub);
1407         if (state->dst.scrub)
1408                 pool_put(&pf_state_scrub_pl, state->dst.scrub);
1409
1410         /* Someday... flush the TCP segment reassembly descriptors. */
1411 }
1412
1413 int
1414 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd,
1415     u_short *reason, struct tcphdr *th, struct pf_state_peer *src,
1416     struct pf_state_peer *dst, int *writeback)
1417 {
1418         u_int8_t hdr[60];
1419         u_int8_t *opt;
1420         int copyback = 0;
1421
1422         KASSERT((src->scrub || dst->scrub),
1423             ("pf_normalize_tcp_statefull: src->scrub && dst->scrub!"));
1424
1425         /*
1426          * Enforce the minimum TTL seen for this connection.  Negate a common
1427          * technique to evade an intrusion detection system and confuse
1428          * firewall state code.
1429          */
1430         switch (pd->af) {
1431 #ifdef INET
1432         case AF_INET: {
1433                 if (src->scrub) {
1434                         struct ip *h = mtod(m, struct ip *);
1435                         if (h->ip_ttl > src->scrub->pfss_ttl)
1436                                 src->scrub->pfss_ttl = h->ip_ttl;
1437                         h->ip_ttl = src->scrub->pfss_ttl;
1438                 }
1439                 break;
1440         }
1441 #endif /* INET */
1442 #ifdef INET6
1443         case AF_INET6: {
1444                 if (src->scrub) {
1445                         struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1446                         if (h->ip6_hlim > src->scrub->pfss_ttl)
1447                                 src->scrub->pfss_ttl = h->ip6_hlim;
1448                         h->ip6_hlim = src->scrub->pfss_ttl;
1449                 }
1450                 break;
1451         }
1452 #endif /* INET6 */
1453         }
1454
1455         if (th->th_off > (sizeof(struct tcphdr) >> 2) &&
1456             ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) ||
1457             (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) &&
1458             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1459                 /* Diddle with TCP options */
1460                 int hlen;
1461                 opt = hdr + sizeof(struct tcphdr);
1462                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1463                 while (hlen >= TCPOLEN_TIMESTAMP) {
1464                         switch (*opt) {
1465                         case TCPOPT_EOL:        /* FALLTHROUGH */
1466                         case TCPOPT_NOP:
1467                                 opt++;
1468                                 hlen--;
1469                                 break;
1470                         case TCPOPT_TIMESTAMP:
1471                                 /* Modulate the timestamps.  Can be used for
1472                                  * NAT detection, OS uptime determination or
1473                                  * reboot detection.
1474                                  */
1475                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1476                                         u_int32_t ts_value;
1477                                         if (src->scrub &&
1478                                             (src->scrub->pfss_flags &
1479                                             PFSS_TIMESTAMP)) {
1480                                                 memcpy(&ts_value, &opt[2],
1481                                                     sizeof(u_int32_t));
1482                                                 ts_value = htonl(ntohl(ts_value)
1483                                                     + src->scrub->pfss_ts_mod);
1484                                                 pf_change_a(&opt[2],
1485                                                     &th->th_sum, ts_value, 0);
1486                                                 copyback = 1;
1487                                         }
1488
1489                                         /* Modulate TS reply iff valid (!0) */
1490                                         memcpy(&ts_value, &opt[6],
1491                                             sizeof(u_int32_t));
1492                                         if (ts_value && dst->scrub &&
1493                                             (dst->scrub->pfss_flags &
1494                                             PFSS_TIMESTAMP)) {
1495                                                 ts_value = htonl(ntohl(ts_value)
1496                                                     - dst->scrub->pfss_ts_mod);
1497                                                 pf_change_a(&opt[6],
1498                                                     &th->th_sum, ts_value, 0);
1499                                                 copyback = 1;
1500                                         }
1501                                 }
1502                                 /* FALLTHROUGH */
1503                         default:
1504                                 hlen -= MAX(opt[1], 2);
1505                                 opt += MAX(opt[1], 2);
1506                                 break;
1507                         }
1508                 }
1509                 if (copyback) {
1510                         /* Copyback the options, caller copys back header */
1511                         *writeback = 1;
1512                         m_copyback(m, off + sizeof(struct tcphdr),
1513                             (th->th_off << 2) - sizeof(struct tcphdr), hdr +
1514                             sizeof(struct tcphdr));
1515                 }
1516         }
1517
1518
1519         /* I have a dream....  TCP segment reassembly.... */
1520         return (0);
1521 }
1522
1523 int
1524 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th,
1525     int off)
1526 {
1527         u_int16_t       *mss;
1528         int              thoff;
1529         int              opt, cnt, optlen = 0;
1530         int              rewrite = 0;
1531         u_char          *optp;
1532
1533         thoff = th->th_off << 2;
1534         cnt = thoff - sizeof(struct tcphdr);
1535         optp = mtod(m, caddr_t) + off + sizeof(struct tcphdr);
1536
1537         for (; cnt > 0; cnt -= optlen, optp += optlen) {
1538                 opt = optp[0];
1539                 if (opt == TCPOPT_EOL)
1540                         break;
1541                 if (opt == TCPOPT_NOP)
1542                         optlen = 1;
1543                 else {
1544                         if (cnt < 2)
1545                                 break;
1546                         optlen = optp[1];
1547                         if (optlen < 2 || optlen > cnt)
1548                                 break;
1549                 }
1550                 switch (opt) {
1551                 case TCPOPT_MAXSEG:
1552                         mss = (u_int16_t *)(optp + 2);
1553                         if ((ntohs(*mss)) > r->max_mss) {
1554                                 th->th_sum = pf_cksum_fixup(th->th_sum,
1555                                     *mss, htons(r->max_mss));
1556                                 *mss = htons(r->max_mss);
1557                                 rewrite = 1;
1558                         }
1559                         break;
1560                 default:
1561                         break;
1562                 }
1563         }
1564
1565         return (rewrite);
1566 }