sys/net/pf/pf_norm.c

   1 /*      $OpenBSD: pf_norm.c,v 1.113 2008/05/07 07:07:29 markus Exp $ */
   2
   3 /*
   4  * Copyright (c) 2010 The DragonFly Project.  All rights reserved.
   5  *
   6  * Copyright 2001 Niels Provos <provos@citi.umich.edu>
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28  */
  29
  30 #include "opt_inet.h"
  31 #include "opt_inet6.h"
  32
  33 #include <sys/param.h>
  34 #include <sys/systm.h>
  35 #include <sys/mbuf.h>
  36 #include <sys/filio.h>
  37 #include <sys/fcntl.h>
  38 #include <sys/socket.h>
  39 #include <sys/kernel.h>
  40 #include <sys/time.h>
  41
  42 #include <net/if.h>
  43 #include <net/if_var.h>
  44 #include <net/if_types.h>
  45 #include <net/bpf.h>
  46 #include <net/route.h>
  47 #include <net/pf/if_pflog.h>
  48
  49 #include <netinet/in.h>
  50 #include <netinet/in_var.h>
  51 #include <netinet/in_systm.h>
  52 #include <netinet/ip.h>
  53 #include <netinet/ip_var.h>
  54 #include <netinet/tcp.h>
  55 #include <netinet/tcp_seq.h>
  56 #include <netinet/udp.h>
  57 #include <netinet/ip_icmp.h>
  58
  59 #ifdef INET6
  60 #include <netinet/ip6.h>
  61 #endif /* INET6 */
  62
  63 #include <net/pf/pfvar.h>
  64
  65 #define PFFRAG_SEENLAST 0x0001          /* Seen the last fragment for this */
  66 #define PFFRAG_NOBUFFER 0x0002          /* Non-buffering fragment cache */
  67 #define PFFRAG_DROP     0x0004          /* Drop all fragments */
  68 #define BUFFER_FRAGMENTS(fr)    (!((fr)->fr_flags & PFFRAG_NOBUFFER))
  69
  70
  71 TAILQ_HEAD(pf_fragqueue, pf_fragment)   *pf_fragqueue;
  72 TAILQ_HEAD(pf_cachequeue, pf_fragment)  *pf_cachequeue;
  73
  74 static __inline int      pf_frag_compare(struct pf_fragment *,
  75                             struct pf_fragment *);
  76 RB_HEAD(pf_frag_tree, pf_fragment)      *pf_frag_tree,
  77                                         *pf_cache_tree;
  78 RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
  79 RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
  80
  81 /* Private prototypes */
  82 void                     pf_ip2key(struct pf_fragment *, struct ip *);
  83 void                     pf_remove_fragment(struct pf_fragment *);
  84 void                     pf_flush_fragments(void);
  85 void                     pf_free_fragment(struct pf_fragment *);
  86 struct pf_fragment      *pf_find_fragment(struct ip *, struct pf_frag_tree *);
  87 struct mbuf             *pf_reassemble(struct mbuf **, struct pf_fragment **,
  88                             struct pf_frent *, int);
  89 struct mbuf             *pf_fragcache(struct mbuf **, struct ip*,
  90                             struct pf_fragment **, int, int, int *);
  91 int                      pf_normalize_tcpopt(struct pf_rule *, struct mbuf *,
  92                             struct tcphdr *, int, sa_family_t);
  93
  94 #define DPFPRINTF(x) do {                               \
  95         if (pf_status.debug >= PF_DEBUG_MISC) {         \
  96                 kprintf("%s: ", __func__);              \
  97                 kprintf x ;                             \
  98         }                                               \
  99 } while(0)
 100
 101 static MALLOC_DEFINE(M_PFFRAGPL, "pffrag", "pf fragment pool list");
 102 static MALLOC_DEFINE(M_PFCACHEPL, "pffrcache", "pf fragment cache pool list");
 103 static MALLOC_DEFINE(M_PFFRENTPL, "pffrent", "pf frent pool list");
 104 static MALLOC_DEFINE(M_PFCENTPL, "pffrcent", "pf fragment cent pool list");
 105 static MALLOC_DEFINE(M_PFSTATESCRUBPL, "pfstatescrub", "pf state scrub pool list");
 106
 107 /* Globals */
 108 struct malloc_type       *pf_frent_pl, *pf_frag_pl, *pf_cache_pl, *pf_cent_pl;
 109 struct malloc_type       *pf_state_scrub_pl;
 110 int                      pf_nfrents, pf_ncache;
 111
 112 void
 113 pf_normalize_init(void)
 114 {
 115         int n;
 116
 117         /* XXX
 118         pool_sethiwat(&pf_frag_pl, PFFRAG_FRAG_HIWAT);
 119         pool_sethardlimit(&pf_frent_pl, PFFRAG_FRENT_HIWAT, NULL, 0);
 120         pool_sethardlimit(&pf_cache_pl, PFFRAG_FRCACHE_HIWAT, NULL, 0);
 121         pool_sethardlimit(&pf_cent_pl, PFFRAG_FRCENT_HIWAT, NULL, 0);
 122         */
 123
 124         /*
 125          * pcpu queues and trees
 126          */
 127         pf_fragqueue = kmalloc(sizeof(*pf_fragqueue) * ncpus,
 128                                 M_PF, M_WAITOK | M_ZERO);
 129         pf_cachequeue = kmalloc(sizeof(*pf_cachequeue) * ncpus,
 130                                 M_PF, M_WAITOK | M_ZERO);
 131         pf_frag_tree = kmalloc(sizeof(*pf_frag_tree) * ncpus,
 132                                 M_PF, M_WAITOK | M_ZERO);
 133         pf_cache_tree = kmalloc(sizeof(*pf_cache_tree) * ncpus,
 134                                 M_PF, M_WAITOK | M_ZERO);
 135
 136         for (n = 0; n < ncpus; ++n) {
 137                 TAILQ_INIT(&pf_fragqueue[n]);
 138                 TAILQ_INIT(&pf_cachequeue[n]);
 139                 RB_INIT(&pf_frag_tree[n]);
 140                 RB_INIT(&pf_cache_tree[n]);
 141         }
 142 }
 143
 144 void
 145 pf_normalize_unload(void)
 146 {
 147         kfree(pf_fragqueue, M_PF);
 148         kfree(pf_cachequeue, M_PF);
 149         kfree(pf_frag_tree, M_PF);
 150         kfree(pf_cache_tree, M_PF);
 151 }
 152
 153 static __inline int
 154 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b)
 155 {
 156         int     diff;
 157
 158         if ((diff = a->fr_id - b->fr_id))
 159                 return (diff);
 160         else if ((diff = a->fr_p - b->fr_p))
 161                 return (diff);
 162         else if (a->fr_src.s_addr < b->fr_src.s_addr)
 163                 return (-1);
 164         else if (a->fr_src.s_addr > b->fr_src.s_addr)
 165                 return (1);
 166         else if (a->fr_dst.s_addr < b->fr_dst.s_addr)
 167                 return (-1);
 168         else if (a->fr_dst.s_addr > b->fr_dst.s_addr)
 169                 return (1);
 170         return (0);
 171 }
 172
 173 void
 174 pf_purge_expired_fragments(void)
 175 {
 176         struct pf_fragment *frag;
 177         u_int32_t expire;
 178         int cpu = mycpu->gd_cpuid;
 179
 180         expire = time_second - pf_default_rule.timeout[PFTM_FRAG];
 181
 182         while ((frag = TAILQ_LAST(&pf_fragqueue[cpu], pf_fragqueue)) != NULL) {
 183                 KASSERT((BUFFER_FRAGMENTS(frag)),
 184                         ("BUFFER_FRAGMENTS(frag) == 0: %s", __func__));
 185                 if (frag->fr_timeout > expire)
 186                         break;
 187
 188                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 189                 pf_free_fragment(frag);
 190         }
 191
 192         while ((frag = TAILQ_LAST(&pf_cachequeue[cpu], pf_cachequeue)) != NULL) {
 193                 KASSERT((!BUFFER_FRAGMENTS(frag)),
 194                         ("BUFFER_FRAGMENTS(frag) != 0: %s", __func__));
 195                 if (frag->fr_timeout > expire)
 196                         break;
 197
 198                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 199                 pf_free_fragment(frag);
 200                 KASSERT((TAILQ_EMPTY(&pf_cachequeue[cpu]) ||
 201                     TAILQ_LAST(&pf_cachequeue[cpu], pf_cachequeue) != frag),
 202                     ("!(TAILQ_EMPTY() || TAILQ_LAST() == farg): %s",
 203                     __func__));
 204         }
 205 }
 206
 207 /*
 208  * Try to flush old fragments to make space for new ones
 209  */
 210
 211 void
 212 pf_flush_fragments(void)
 213 {
 214         struct pf_fragment *frag;
 215         int goal;
 216         int cpu = mycpu->gd_cpuid;
 217
 218         goal = pf_nfrents * 9 / 10;
 219         DPFPRINTF(("trying to free > %d frents\n",
 220             pf_nfrents - goal));
 221         while (goal < pf_nfrents) {
 222                 frag = TAILQ_LAST(&pf_fragqueue[cpu], pf_fragqueue);
 223                 if (frag == NULL)
 224                         break;
 225                 pf_free_fragment(frag);
 226         }
 227
 228
 229         goal = pf_ncache * 9 / 10;
 230         DPFPRINTF(("trying to free > %d cache entries\n",
 231             pf_ncache - goal));
 232         while (goal < pf_ncache) {
 233                 frag = TAILQ_LAST(&pf_cachequeue[cpu], pf_cachequeue);
 234                 if (frag == NULL)
 235                         break;
 236                 pf_free_fragment(frag);
 237         }
 238 }
 239
 240 /* Frees the fragments and all associated entries */
 241
 242 void
 243 pf_free_fragment(struct pf_fragment *frag)
 244 {
 245         struct pf_frent         *frent;
 246         struct pf_frcache       *frcache;
 247
 248         /* Free all fragments */
 249         if (BUFFER_FRAGMENTS(frag)) {
 250                 for (frent = LIST_FIRST(&frag->fr_queue); frent;
 251                     frent = LIST_FIRST(&frag->fr_queue)) {
 252                         LIST_REMOVE(frent, fr_next);
 253
 254                         m_freem(frent->fr_m);
 255                         kfree(frent, M_PFFRENTPL);
 256                         pf_nfrents--;
 257                 }
 258         } else {
 259                 for (frcache = LIST_FIRST(&frag->fr_cache); frcache;
 260                     frcache = LIST_FIRST(&frag->fr_cache)) {
 261                         LIST_REMOVE(frcache, fr_next);
 262
 263                         KASSERT((LIST_EMPTY(&frag->fr_cache) ||
 264                             LIST_FIRST(&frag->fr_cache)->fr_off >
 265                             frcache->fr_end),
 266                             ("! (LIST_EMPTY() || LIST_FIRST()->fr_off >"
 267                              " frcache->fr_end): %s", __func__));
 268
 269                         kfree(frcache, M_PFCENTPL);
 270                         pf_ncache--;
 271                 }
 272         }
 273
 274         pf_remove_fragment(frag);
 275 }
 276
 277 void
 278 pf_ip2key(struct pf_fragment *key, struct ip *ip)
 279 {
 280         key->fr_p = ip->ip_p;
 281         key->fr_id = ip->ip_id;
 282         key->fr_src.s_addr = ip->ip_src.s_addr;
 283         key->fr_dst.s_addr = ip->ip_dst.s_addr;
 284 }
 285
 286 struct pf_fragment *
 287 pf_find_fragment(struct ip *ip, struct pf_frag_tree *tree)
 288 {
 289         struct pf_fragment       key;
 290         struct pf_fragment      *frag;
 291         int cpu = mycpu->gd_cpuid;
 292
 293         pf_ip2key(&key, ip);
 294
 295         frag = RB_FIND(pf_frag_tree, tree, &key);
 296         if (frag != NULL) {
 297                 /* XXX Are we sure we want to update the timeout? */
 298                 frag->fr_timeout = time_second;
 299                 if (BUFFER_FRAGMENTS(frag)) {
 300                         TAILQ_REMOVE(&pf_fragqueue[cpu], frag, frag_next);
 301                         TAILQ_INSERT_HEAD(&pf_fragqueue[cpu], frag, frag_next);
 302                 } else {
 303                         TAILQ_REMOVE(&pf_cachequeue[cpu], frag, frag_next);
 304                         TAILQ_INSERT_HEAD(&pf_cachequeue[cpu], frag, frag_next);
 305                 }
 306         }
 307
 308         return (frag);
 309 }
 310
 311 /* Removes a fragment from the fragment queue and frees the fragment */
 312
 313 void
 314 pf_remove_fragment(struct pf_fragment *frag)
 315 {
 316         int cpu = mycpu->gd_cpuid;
 317
 318         if (BUFFER_FRAGMENTS(frag)) {
 319                 RB_REMOVE(pf_frag_tree, &pf_frag_tree[cpu], frag);
 320                 TAILQ_REMOVE(&pf_fragqueue[cpu], frag, frag_next);
 321                 kfree(frag, M_PFFRAGPL);
 322         } else {
 323                 RB_REMOVE(pf_frag_tree, &pf_cache_tree[cpu], frag);
 324                 TAILQ_REMOVE(&pf_cachequeue[cpu], frag, frag_next);
 325                 kfree(frag, M_PFCACHEPL);
 326         }
 327 }
 328
 329 #define FR_IP_OFF(fr)   (((fr)->fr_ip->ip_off & IP_OFFMASK) << 3)
 330 struct mbuf *
 331 pf_reassemble(struct mbuf **m0, struct pf_fragment **frag,
 332     struct pf_frent *frent, int mff)
 333 {
 334         struct mbuf     *m = *m0, *m2;
 335         struct pf_frent *frea, *next;
 336         struct pf_frent *frep = NULL;
 337         struct ip       *ip = frent->fr_ip;
 338         int             hlen = ip->ip_hl << 2;
 339         u_int16_t       off = (ip->ip_off & IP_OFFMASK) << 3;
 340         u_int16_t       ip_len = ip->ip_len - ip->ip_hl * 4;
 341         u_int16_t       max = ip_len + off;
 342         int             cpu = mycpu->gd_cpuid;
 343
 344         KASSERT((*frag == NULL || BUFFER_FRAGMENTS(*frag)),
 345             ("! (*frag == NULL || BUFFER_FRAGMENTS(*frag)): %s", __func__));
 346
 347         /* Strip off ip header */
 348         m->m_data += hlen;
 349         m->m_len -= hlen;
 350
 351         /* Create a new reassembly queue for this packet */
 352         if (*frag == NULL) {
 353                 *frag = kmalloc(sizeof(struct pf_fragment), M_PFFRAGPL, M_NOWAIT);
 354                 if (*frag == NULL) {
 355                         pf_flush_fragments();
 356                         *frag = kmalloc(sizeof(struct pf_fragment), M_PFFRAGPL, M_NOWAIT);
 357                         if (*frag == NULL)
 358                                 goto drop_fragment;
 359                 }
 360
 361                 (*frag)->fr_flags = 0;
 362                 (*frag)->fr_max = 0;
 363                 (*frag)->fr_src = frent->fr_ip->ip_src;
 364                 (*frag)->fr_dst = frent->fr_ip->ip_dst;
 365                 (*frag)->fr_p = frent->fr_ip->ip_p;
 366                 (*frag)->fr_id = frent->fr_ip->ip_id;
 367                 (*frag)->fr_timeout = time_second;
 368                 LIST_INIT(&(*frag)->fr_queue);
 369
 370                 RB_INSERT(pf_frag_tree, &pf_frag_tree[cpu], *frag);
 371                 TAILQ_INSERT_HEAD(&pf_fragqueue[cpu], *frag, frag_next);
 372
 373                 /* We do not have a previous fragment */
 374                 frep = NULL;
 375                 goto insert;
 376         }
 377
 378         /*
 379          * Find a fragment after the current one:
 380          *  - off contains the real shifted offset.
 381          */
 382         LIST_FOREACH(frea, &(*frag)->fr_queue, fr_next) {
 383                 if (FR_IP_OFF(frea) > off)
 384                         break;
 385                 frep = frea;
 386         }
 387
 388         KASSERT((frep != NULL || frea != NULL),
 389             ("!(frep != NULL || frea != NULL): %s", __func__));
 390
 391         if (frep != NULL &&
 392             FR_IP_OFF(frep) + frep->fr_ip->ip_len - frep->fr_ip->ip_hl *
 393             4 > off)
 394         {
 395                 u_int16_t       precut;
 396
 397                 precut = FR_IP_OFF(frep) + frep->fr_ip->ip_len -
 398                     frep->fr_ip->ip_hl * 4 - off;
 399                 if (precut >= ip_len)
 400                         goto drop_fragment;
 401                 m_adj(frent->fr_m, precut);
 402                 DPFPRINTF(("overlap -%d\n", precut));
 403                 /* Enforce 8 byte boundaries */
 404                 ip->ip_off = ip->ip_off + (precut >> 3);
 405                 off = (ip->ip_off & IP_OFFMASK) << 3;
 406                 ip_len -= precut;
 407                 ip->ip_len = ip_len;
 408         }
 409
 410         for (; frea != NULL && ip_len + off > FR_IP_OFF(frea);
 411             frea = next)
 412         {
 413                 u_int16_t       aftercut;
 414
 415                 aftercut = ip_len + off - FR_IP_OFF(frea);
 416                 DPFPRINTF(("adjust overlap %d\n", aftercut));
 417                 if (aftercut < frea->fr_ip->ip_len - frea->fr_ip->ip_hl
 418                     * 4)
 419                 {
 420                         frea->fr_ip->ip_len =
 421                             frea->fr_ip->ip_len - aftercut;
 422                         frea->fr_ip->ip_off = frea->fr_ip->ip_off +
 423                             (aftercut >> 3);
 424                         m_adj(frea->fr_m, aftercut);
 425                         break;
 426                 }
 427
 428                 /* This fragment is completely overlapped, lose it */
 429                 next = LIST_NEXT(frea, fr_next);
 430                 m_freem(frea->fr_m);
 431                 LIST_REMOVE(frea, fr_next);
 432                 kfree(frea, M_PFFRENTPL);
 433                 pf_nfrents--;
 434         }
 435
 436  insert:
 437         /* Update maximum data size */
 438         if ((*frag)->fr_max < max)
 439                 (*frag)->fr_max = max;
 440         /* This is the last segment */
 441         if (!mff)
 442                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
 443
 444         if (frep == NULL)
 445                 LIST_INSERT_HEAD(&(*frag)->fr_queue, frent, fr_next);
 446         else
 447                 LIST_INSERT_AFTER(frep, frent, fr_next);
 448
 449         /* Check if we are completely reassembled */
 450         if (!((*frag)->fr_flags & PFFRAG_SEENLAST))
 451                 return (NULL);
 452
 453         /* Check if we have all the data */
 454         off = 0;
 455         for (frep = LIST_FIRST(&(*frag)->fr_queue); frep; frep = next) {
 456                 next = LIST_NEXT(frep, fr_next);
 457
 458                 off += frep->fr_ip->ip_len - frep->fr_ip->ip_hl * 4;
 459                 if (off < (*frag)->fr_max &&
 460                     (next == NULL || FR_IP_OFF(next) != off))
 461                 {
 462                         DPFPRINTF(("missing fragment at %d, next %d, max %d\n",
 463                             off, next == NULL ? -1 : FR_IP_OFF(next),
 464                             (*frag)->fr_max));
 465                         return (NULL);
 466                 }
 467         }
 468         DPFPRINTF(("%d < %d?\n", off, (*frag)->fr_max));
 469         if (off < (*frag)->fr_max)
 470                 return (NULL);
 471
 472         /* We have all the data */
 473         frent = LIST_FIRST(&(*frag)->fr_queue);
 474         KASSERT((frent != NULL), ("frent == NULL: %s", __func__));
 475         if ((frent->fr_ip->ip_hl << 2) + off > IP_MAXPACKET) {
 476                 DPFPRINTF(("drop: too big: %d\n", off));
 477                 pf_free_fragment(*frag);
 478                 *frag = NULL;
 479                 return (NULL);
 480         }
 481         next = LIST_NEXT(frent, fr_next);
 482
 483         /* Magic from ip_input */
 484         ip = frent->fr_ip;
 485         m = frent->fr_m;
 486         m2 = m->m_next;
 487         m->m_next = NULL;
 488         m_cat(m, m2);
 489         kfree(frent, M_PFFRENTPL);
 490         pf_nfrents--;
 491         for (frent = next; frent != NULL; frent = next) {
 492                 next = LIST_NEXT(frent, fr_next);
 493
 494                 m2 = frent->fr_m;
 495                 kfree(frent, M_PFFRENTPL);
 496                 pf_nfrents--;
 497                 m_cat(m, m2);
 498         }
 499
 500         ip->ip_src = (*frag)->fr_src;
 501         ip->ip_dst = (*frag)->fr_dst;
 502
 503         /* Remove from fragment queue */
 504         pf_remove_fragment(*frag);
 505         *frag = NULL;
 506
 507         hlen = ip->ip_hl << 2;
 508         ip->ip_len = off + hlen;
 509         m->m_len += hlen;
 510         m->m_data -= hlen;
 511
 512         /* some debugging cruft by sklower, below, will go away soon */
 513         /* XXX this should be done elsewhere */
 514         if (m->m_flags & M_PKTHDR) {
 515                 int plen = 0;
 516                 for (m2 = m; m2; m2 = m2->m_next)
 517                         plen += m2->m_len;
 518                 m->m_pkthdr.len = plen;
 519         }
 520
 521         DPFPRINTF(("complete: %p(%d)\n", m, ip->ip_len));
 522         return (m);
 523
 524  drop_fragment:
 525         /* Oops - fail safe - drop packet */
 526         kfree(frent, M_PFFRENTPL);
 527         pf_nfrents--;
 528         m_freem(m);
 529         return (NULL);
 530 }
 531
 532 struct mbuf *
 533 pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff,
 534     int drop, int *nomem)
 535 {
 536         struct mbuf     *m = *m0;
 537         struct pf_frcache *frp, *fra, *cur = NULL;
 538         int             ip_len = h->ip_len - (h->ip_hl << 2);
 539         u_int16_t       off = h->ip_off << 3;
 540         u_int16_t       max = ip_len + off;
 541         int             hosed = 0;
 542         int             cpu = mycpu->gd_cpuid;
 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 = kmalloc(sizeof(struct pf_fragment), M_PFCACHEPL, M_NOWAIT);
 550                 if (*frag == NULL) {
 551                         pf_flush_fragments();
 552                         *frag = kmalloc(sizeof(struct pf_fragment), M_PFCACHEPL, M_NOWAIT);
 553                         if (*frag == NULL)
 554                                 goto no_mem;
 555                 }
 556
 557                 /* Get an entry for the queue */
 558                 cur = kmalloc(sizeof(struct pf_frcache), M_PFCENTPL, M_NOWAIT);
 559                 if (cur == NULL) {
 560                         kfree(*frag, M_PFCACHEPL);
 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[cpu], *frag);
 580                 TAILQ_INSERT_HEAD(&pf_cachequeue[cpu], *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, M_NOWAIT);
 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 = kmalloc(sizeof(struct pf_frcache), M_PFCENTPL, M_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 = kmalloc(sizeof(struct pf_frcache), M_PFCENTPL, M_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                                 kfree(cur, M_PFCENTPL);
 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                                 kfree(frp, M_PFCENTPL);
 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     struct pf_pdesc *pd)
 842 {
 843         struct mbuf     *m = *m0;
 844         struct pf_rule  *r;
 845         struct pf_frent *frent;
 846         struct pf_fragment *frag = NULL;
 847         struct ip       *h = mtod(m, struct ip *);
 848         int             mff = (h->ip_off & IP_MF);
 849         int             hlen = h->ip_hl << 2;
 850         u_int16_t       fragoff = (h->ip_off & IP_OFFMASK) << 3;
 851         u_int16_t       max;
 852         int             ip_len;
 853         int             tag = -1;
 854         int             cpu = mycpu->gd_cpuid;
 855
 856         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
 857         while (r != NULL) {
 858                 r->evaluations++;
 859                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
 860                         r = r->skip[PF_SKIP_IFP].ptr;
 861                 else if (r->direction && r->direction != dir)
 862                         r = r->skip[PF_SKIP_DIR].ptr;
 863                 else if (r->af && r->af != AF_INET)
 864                         r = r->skip[PF_SKIP_AF].ptr;
 865                 else if (r->proto && r->proto != h->ip_p)
 866                         r = r->skip[PF_SKIP_PROTO].ptr;
 867                 else if (PF_MISMATCHAW(&r->src.addr,
 868                     (struct pf_addr *)&h->ip_src.s_addr, AF_INET,
 869                     r->src.neg, kif))
 870                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
 871                 else if (PF_MISMATCHAW(&r->dst.addr,
 872                     (struct pf_addr *)&h->ip_dst.s_addr, AF_INET,
 873                     r->dst.neg, NULL))
 874                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
 875                 else if (r->match_tag && !pf_match_tag(m, r, &tag))
 876                         r = TAILQ_NEXT(r, entries);
 877                 else
 878                         break;
 879         }
 880
 881         if (r == NULL || r->action == PF_NOSCRUB)
 882                 return (PF_PASS);
 883         else {
 884                 r->packets[dir == PF_OUT]++;
 885                 r->bytes[dir == PF_OUT] += pd->tot_len;
 886         }
 887
 888         /* Check for illegal packets */
 889         if (hlen < (int)sizeof(struct ip))
 890                 goto drop;
 891
 892         if (hlen > h->ip_len)
 893                 goto drop;
 894
 895         /* Clear IP_DF if the rule uses the no-df option */
 896         if (r->rule_flag & PFRULE_NODF && h->ip_off & IP_DF) {
 897                 u_int16_t ip_off = h->ip_off;
 898
 899                 h->ip_off &= ~IP_DF;
 900                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
 901         }
 902
 903         /* We will need other tests here */
 904         if (!fragoff && !mff)
 905                 goto no_fragment;
 906
 907         /* A fragment; rehash required. */
 908         m->m_flags &= ~M_HASH;
 909
 910         /* We're dealing with a fragment now. Don't allow fragments
 911          * with IP_DF to enter the cache. If the flag was cleared by
 912          * no-df above, fine. Otherwise drop it.
 913          */
 914         if (h->ip_off & IP_DF) {
 915                 DPFPRINTF(("IP_DF\n"));
 916                 goto bad;
 917         }
 918
 919         ip_len = h->ip_len - hlen;
 920
 921         /* All fragments are 8 byte aligned */
 922         if (mff && (ip_len & 0x7)) {
 923                 DPFPRINTF(("mff and %d\n", ip_len));
 924                 goto bad;
 925         }
 926
 927         /* Respect maximum length */
 928         if (fragoff + ip_len > IP_MAXPACKET) {
 929                 DPFPRINTF(("max packet %d\n", fragoff + ip_len));
 930                 goto bad;
 931         }
 932         max = fragoff + ip_len;
 933
 934         if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) {
 935                 /* Fully buffer all of the fragments */
 936
 937                 frag = pf_find_fragment(h, &pf_frag_tree[cpu]);
 938
 939                 /* Check if we saw the last fragment already */
 940                 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
 941                     max > frag->fr_max)
 942                         goto bad;
 943
 944                 /* Get an entry for the fragment queue */
 945                 frent = kmalloc(sizeof(struct pf_frent), M_PFFRENTPL, M_NOWAIT);
 946                 if (frent == NULL) {
 947                         REASON_SET(reason, PFRES_MEMORY);
 948                         return (PF_DROP);
 949                 }
 950                 pf_nfrents++;
 951                 frent->fr_ip = h;
 952                 frent->fr_m = m;
 953
 954                 /* Might return a completely reassembled mbuf, or NULL */
 955                 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
 956                 *m0 = m = pf_reassemble(m0, &frag, frent, mff);
 957
 958                 if (m == NULL)
 959                         return (PF_DROP);
 960
 961                 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
 962                         goto drop;
 963
 964                 h = mtod(m, struct ip *);
 965         } else {
 966                 /* non-buffering fragment cache (drops or masks overlaps) */
 967                 int     nomem = 0;
 968
 969                 if (dir == PF_OUT && m->m_pkthdr.pf.flags & PF_TAG_FRAGCACHE) {
 970                         /*
 971                          * Already passed the fragment cache in the
 972                          * input direction.  If we continued, it would
 973                          * appear to be a dup and would be dropped.
 974                          */
 975                         goto fragment_pass;
 976                 }
 977
 978                 frag = pf_find_fragment(h, &pf_cache_tree[cpu]);
 979
 980                 /* Check if we saw the last fragment already */
 981                 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
 982                     max > frag->fr_max) {
 983                         if (r->rule_flag & PFRULE_FRAGDROP)
 984                                 frag->fr_flags |= PFFRAG_DROP;
 985                         goto bad;
 986                 }
 987
 988                 *m0 = m = pf_fragcache(m0, h, &frag, mff,
 989                     (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem);
 990                 if (m == NULL) {
 991                         if (nomem)
 992                                 goto no_mem;
 993                         goto drop;
 994                 }
 995
 996                 if (dir == PF_IN)
 997                         m->m_pkthdr.pf.flags |= PF_TAG_FRAGCACHE;
 998
 999                 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
1000                         goto drop;
1001                 goto fragment_pass;
1002         }
1003
1004  no_fragment:
1005         /* At this point, only IP_DF is allowed in ip_off */
1006         if (h->ip_off & ~IP_DF) {
1007                 u_int16_t ip_off = h->ip_off;
1008
1009                 h->ip_off &= IP_DF;
1010                 h->ip_sum = pf_cksum_fixup(h->ip_sum, htons(ip_off), htons(h->ip_off), 0);
1011         }
1012
1013         /* Enforce a minimum ttl, may cause endless packet loops */
1014         if (r->min_ttl && h->ip_ttl < r->min_ttl) {
1015                 u_int16_t ip_ttl = h->ip_ttl;
1016
1017                 h->ip_ttl = r->min_ttl;
1018                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
1019         }
1020
1021         /* Enforce tos */
1022         if (r->rule_flag & PFRULE_SET_TOS) {
1023                 u_int16_t       ov, nv;
1024
1025                 ov = *(u_int16_t *)h;
1026                 h->ip_tos = r->set_tos;
1027                 nv = *(u_int16_t *)h;
1028
1029                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0);
1030         }
1031
1032         if (r->rule_flag & PFRULE_RANDOMID) {
1033                 u_int16_t ip_id = h->ip_id;
1034
1035                 h->ip_id = ip_randomid();
1036                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0);
1037         }
1038         if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0)
1039                 pd->flags |= PFDESC_IP_REAS;
1040
1041         return (PF_PASS);
1042
1043  fragment_pass:
1044         /* Enforce a minimum ttl, may cause endless packet loops */
1045         if (r->min_ttl && h->ip_ttl < r->min_ttl) {
1046                 u_int16_t ip_ttl = h->ip_ttl;
1047
1048                 h->ip_ttl = r->min_ttl;
1049                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
1050         }
1051         /* Enforce tos */
1052         if (r->rule_flag & PFRULE_SET_TOS) {
1053                 u_int16_t       ov, nv;
1054
1055                 ov = *(u_int16_t *)h;
1056                 h->ip_tos = r->set_tos;
1057                 nv = *(u_int16_t *)h;
1058
1059                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0);
1060         }
1061         if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0)
1062                 pd->flags |= PFDESC_IP_REAS;
1063         return (PF_PASS);
1064
1065  no_mem:
1066         REASON_SET(reason, PFRES_MEMORY);
1067         if (r != NULL && r->log)
1068                 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL, pd);
1069         return (PF_DROP);
1070
1071  drop:
1072         REASON_SET(reason, PFRES_NORM);
1073         if (r != NULL && r->log)
1074                 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL, pd);
1075         return (PF_DROP);
1076
1077  bad:
1078         DPFPRINTF(("dropping bad fragment\n"));
1079
1080         /* Free associated fragments */
1081         if (frag != NULL)
1082                 pf_free_fragment(frag);
1083
1084         REASON_SET(reason, PFRES_FRAG);
1085         if (r != NULL && r->log)
1086                 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL, pd);
1087
1088         return (PF_DROP);
1089 }
1090
1091 #ifdef INET6
1092 int
1093 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif,
1094     u_short *reason, struct pf_pdesc *pd)
1095 {
1096         struct mbuf             *m = *m0;
1097         struct pf_rule          *r;
1098         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
1099         int                      off;
1100         struct ip6_ext           ext;
1101         struct ip6_opt           opt;
1102         struct ip6_opt_jumbo     jumbo;
1103         struct ip6_frag          frag;
1104         u_int32_t                jumbolen = 0, plen;
1105         u_int16_t                fragoff = 0;
1106         int                      optend;
1107         int                      ooff;
1108         u_int8_t                 proto;
1109         int                      terminal;
1110
1111         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1112         while (r != NULL) {
1113                 r->evaluations++;
1114                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1115                         r = r->skip[PF_SKIP_IFP].ptr;
1116                 else if (r->direction && r->direction != dir)
1117                         r = r->skip[PF_SKIP_DIR].ptr;
1118                 else if (r->af && r->af != AF_INET6)
1119                         r = r->skip[PF_SKIP_AF].ptr;
1120 #if 0 /* header chain! */
1121                 else if (r->proto && r->proto != h->ip6_nxt)
1122                         r = r->skip[PF_SKIP_PROTO].ptr;
1123 #endif
1124                 else if (PF_MISMATCHAW(&r->src.addr,
1125                     (struct pf_addr *)&h->ip6_src, AF_INET6,
1126                     r->src.neg, kif))
1127                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1128                 else if (PF_MISMATCHAW(&r->dst.addr,
1129                     (struct pf_addr *)&h->ip6_dst, AF_INET6,
1130                     r->dst.neg, NULL))
1131                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1132                 else
1133                         break;
1134         }
1135
1136         if (r == NULL || r->action == PF_NOSCRUB)
1137                 return (PF_PASS);
1138         else {
1139                 r->packets[dir == PF_OUT]++;
1140                 r->bytes[dir == PF_OUT] += pd->tot_len;
1141         }
1142
1143         /* Check for illegal packets */
1144         if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len)
1145                 goto drop;
1146
1147         off = sizeof(struct ip6_hdr);
1148         proto = h->ip6_nxt;
1149         terminal = 0;
1150         do {
1151                 switch (proto) {
1152                 case IPPROTO_FRAGMENT:
1153                         goto fragment;
1154                         break;
1155                 case IPPROTO_AH:
1156                 case IPPROTO_ROUTING:
1157                 case IPPROTO_DSTOPTS:
1158                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1159                             NULL, AF_INET6))
1160                                 goto shortpkt;
1161                         if (proto == IPPROTO_AH)
1162                                 off += (ext.ip6e_len + 2) * 4;
1163                         else
1164                                 off += (ext.ip6e_len + 1) * 8;
1165                         proto = ext.ip6e_nxt;
1166                         break;
1167                 case IPPROTO_HOPOPTS:
1168                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1169                             NULL, AF_INET6))
1170                                 goto shortpkt;
1171                         optend = off + (ext.ip6e_len + 1) * 8;
1172                         ooff = off + sizeof(ext);
1173                         do {
1174                                 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type,
1175                                     sizeof(opt.ip6o_type), NULL, NULL,
1176                                     AF_INET6))
1177                                         goto shortpkt;
1178                                 if (opt.ip6o_type == IP6OPT_PAD1) {
1179                                         ooff++;
1180                                         continue;
1181                                 }
1182                                 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt),
1183                                     NULL, NULL, AF_INET6))
1184                                         goto shortpkt;
1185                                 if (ooff + sizeof(opt) + opt.ip6o_len > optend)
1186                                         goto drop;
1187                                 switch (opt.ip6o_type) {
1188                                 case IP6OPT_JUMBO:
1189                                         if (h->ip6_plen != 0)
1190                                                 goto drop;
1191                                         if (!pf_pull_hdr(m, ooff, &jumbo,
1192                                             sizeof(jumbo), NULL, NULL,
1193                                             AF_INET6))
1194                                                 goto shortpkt;
1195                                         memcpy(&jumbolen, jumbo.ip6oj_jumbo_len,
1196                                             sizeof(jumbolen));
1197                                         jumbolen = ntohl(jumbolen);
1198                                         if (jumbolen <= IPV6_MAXPACKET)
1199                                                 goto drop;
1200                                         if (sizeof(struct ip6_hdr) + jumbolen !=
1201                                             m->m_pkthdr.len)
1202                                                 goto drop;
1203                                         break;
1204                                 default:
1205                                         break;
1206                                 }
1207                                 ooff += sizeof(opt) + opt.ip6o_len;
1208                         } while (ooff < optend);
1209
1210                         off = optend;
1211                         proto = ext.ip6e_nxt;
1212                         break;
1213                 default:
1214                         terminal = 1;
1215                         break;
1216                 }
1217         } while (!terminal);
1218
1219         /* jumbo payload option must be present, or plen > 0 */
1220         if (ntohs(h->ip6_plen) == 0)
1221                 plen = jumbolen;
1222         else
1223                 plen = ntohs(h->ip6_plen);
1224         if (plen == 0)
1225                 goto drop;
1226         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1227                 goto shortpkt;
1228
1229         /* Enforce a minimum ttl, may cause endless packet loops */
1230         if (r->min_ttl && h->ip6_hlim < r->min_ttl)
1231                 h->ip6_hlim = r->min_ttl;
1232
1233         return (PF_PASS);
1234
1235  fragment:
1236         if (ntohs(h->ip6_plen) == 0 || jumbolen)
1237                 goto drop;
1238         plen = ntohs(h->ip6_plen);
1239
1240         if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6))
1241                 goto shortpkt;
1242         fragoff = ntohs(frag.ip6f_offlg & IP6F_OFF_MASK);
1243         if (fragoff + (plen - off - sizeof(frag)) > IPV6_MAXPACKET)
1244                 goto badfrag;
1245
1246         /* do something about it */
1247         /* remember to set pd->flags |= PFDESC_IP_REAS */
1248         return (PF_PASS);
1249
1250  shortpkt:
1251         REASON_SET(reason, PFRES_SHORT);
1252         if (r != NULL && r->log)
1253                 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL, pd);
1254         return (PF_DROP);
1255
1256  drop:
1257         REASON_SET(reason, PFRES_NORM);
1258         if (r != NULL && r->log)
1259                 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL, pd);
1260         return (PF_DROP);
1261
1262  badfrag:
1263         REASON_SET(reason, PFRES_FRAG);
1264         if (r != NULL && r->log)
1265                 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL, pd);
1266         return (PF_DROP);
1267 }
1268 #endif /* INET6 */
1269
1270 int
1271 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff,
1272     int off, void *h, struct pf_pdesc *pd)
1273 {
1274         struct pf_rule  *r, *rm = NULL;
1275         struct tcphdr   *th = pd->hdr.tcp;
1276         int              rewrite = 0;
1277         u_short          reason;
1278         u_int8_t         flags;
1279         sa_family_t      af = pd->af;
1280
1281         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1282         while (r != NULL) {
1283                 r->evaluations++;
1284                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1285                         r = r->skip[PF_SKIP_IFP].ptr;
1286                 else if (r->direction && r->direction != dir)
1287                         r = r->skip[PF_SKIP_DIR].ptr;
1288                 else if (r->af && r->af != af)
1289                         r = r->skip[PF_SKIP_AF].ptr;
1290                 else if (r->proto && r->proto != pd->proto)
1291                         r = r->skip[PF_SKIP_PROTO].ptr;
1292                 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af,
1293                     r->src.neg, kif))
1294                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1295                 else if (r->src.port_op && !pf_match_port(r->src.port_op,
1296                             r->src.port[0], r->src.port[1], th->th_sport))
1297                         r = r->skip[PF_SKIP_SRC_PORT].ptr;
1298                 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af,
1299                     r->dst.neg, NULL))
1300                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1301                 else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
1302                             r->dst.port[0], r->dst.port[1], th->th_dport))
1303                         r = r->skip[PF_SKIP_DST_PORT].ptr;
1304                 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match(
1305                             pf_osfp_fingerprint(pd, m, off, th),
1306                             r->os_fingerprint))
1307                         r = TAILQ_NEXT(r, entries);
1308                 else {
1309                         rm = r;
1310                         break;
1311                 }
1312         }
1313
1314         if (rm == NULL || rm->action == PF_NOSCRUB)
1315                 return (PF_PASS);
1316         else {
1317                 r->packets[dir == PF_OUT]++;
1318                 r->bytes[dir == PF_OUT] += pd->tot_len;
1319         }
1320
1321         if (rm->rule_flag & PFRULE_REASSEMBLE_TCP)
1322                 pd->flags |= PFDESC_TCP_NORM;
1323
1324         flags = th->th_flags;
1325         if (flags & TH_SYN) {
1326                 /* Illegal packet */
1327                 if (flags & TH_RST)
1328                         goto tcp_drop;
1329
1330                 if (flags & TH_FIN)
1331                         flags &= ~TH_FIN;
1332         } else {
1333                 /* Illegal packet */
1334                 if (!(flags & (TH_ACK|TH_RST)))
1335                         goto tcp_drop;
1336         }
1337
1338         if (!(flags & TH_ACK)) {
1339                 /* These flags are only valid if ACK is set */
1340                 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG))
1341                         goto tcp_drop;
1342         }
1343
1344         /* Check for illegal header length */
1345         if (th->th_off < (sizeof(struct tcphdr) >> 2))
1346                 goto tcp_drop;
1347
1348         /* If flags changed, or reserved data set, then adjust */
1349         if (flags != th->th_flags || th->th_x2 != 0) {
1350                 u_int16_t       ov, nv;
1351
1352                 ov = *(u_int16_t *)(&th->th_ack + 1);
1353                 th->th_flags = flags;
1354                 th->th_x2 = 0;
1355                 nv = *(u_int16_t *)(&th->th_ack + 1);
1356
1357                 th->th_sum = pf_cksum_fixup(th->th_sum, ov, nv, 0);
1358                 rewrite = 1;
1359         }
1360
1361         /* Remove urgent pointer, if TH_URG is not set */
1362         if (!(flags & TH_URG) && th->th_urp) {
1363                 th->th_sum = pf_cksum_fixup(th->th_sum, th->th_urp, 0, 0);
1364                 th->th_urp = 0;
1365                 rewrite = 1;
1366         }
1367
1368         /* Process options */
1369         if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af))
1370                 rewrite = 1;
1371
1372         /* copy back packet headers if we sanitized */
1373         if (rewrite)
1374                 m_copyback(m, off, sizeof(*th), (caddr_t)th);
1375
1376         return (PF_PASS);
1377
1378  tcp_drop:
1379         REASON_SET(&reason, PFRES_NORM);
1380         if (rm != NULL && r->log)
1381                 PFLOG_PACKET(kif, h, m, AF_INET, dir, reason, r, NULL, NULL, pd);
1382         return (PF_DROP);
1383 }
1384
1385 int
1386 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd,
1387     struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst)
1388 {
1389         u_int32_t tsval, tsecr;
1390         u_int8_t hdr[60];
1391         u_int8_t *opt;
1392
1393         KASSERT((src->scrub == NULL),
1394             ("pf_normalize_tcp_init: src->scrub != NULL"));
1395
1396         src->scrub = kmalloc(sizeof(struct pf_state_scrub), M_PFSTATESCRUBPL,
1397             M_NOWAIT | M_ZERO);
1398         if (src->scrub == NULL)
1399                 return (1);
1400
1401         switch (pd->af) {
1402 #ifdef INET
1403         case AF_INET: {
1404                 struct ip *h = mtod(m, struct ip *);
1405                 src->scrub->pfss_ttl = h->ip_ttl;
1406                 break;
1407         }
1408 #endif /* INET */
1409 #ifdef INET6
1410         case AF_INET6: {
1411                 struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1412                 src->scrub->pfss_ttl = h->ip6_hlim;
1413                 break;
1414         }
1415 #endif /* INET6 */
1416         }
1417
1418
1419         /*
1420          * All normalizations below are only begun if we see the start of
1421          * the connections.  They must all set an enabled bit in pfss_flags
1422          */
1423         if ((th->th_flags & TH_SYN) == 0)
1424                 return (0);
1425
1426
1427         if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub &&
1428             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1429                 /* Diddle with TCP options */
1430                 int hlen;
1431                 opt = hdr + sizeof(struct tcphdr);
1432                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1433                 while (hlen >= TCPOLEN_TIMESTAMP) {
1434                         switch (*opt) {
1435                         case TCPOPT_EOL:        /* FALLTHROUGH */
1436                         case TCPOPT_NOP:
1437                                 opt++;
1438                                 hlen--;
1439                                 break;
1440                         case TCPOPT_TIMESTAMP:
1441                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1442                                         src->scrub->pfss_flags |=
1443                                             PFSS_TIMESTAMP;
1444                                         src->scrub->pfss_ts_mod = karc4random();
1445
1446                                         /* note PFSS_PAWS not set yet */
1447                                         memcpy(&tsval, &opt[2],
1448                                             sizeof(u_int32_t));
1449                                         memcpy(&tsecr, &opt[6],
1450                                             sizeof(u_int32_t));
1451                                         src->scrub->pfss_tsval0 = ntohl(tsval);
1452                                         src->scrub->pfss_tsval = ntohl(tsval);
1453                                         src->scrub->pfss_tsecr = ntohl(tsecr);
1454                                         getmicrouptime(&src->scrub->pfss_last);
1455                                 }
1456                                 /* FALLTHROUGH */
1457                         default:
1458                                 hlen -= MAX(opt[1], 2);
1459                                 opt += MAX(opt[1], 2);
1460                                 break;
1461                         }
1462                 }
1463         }
1464
1465         return (0);
1466 }
1467
1468 void
1469 pf_normalize_tcp_cleanup(struct pf_state *state)
1470 {
1471         if (state->src.scrub)
1472                 kfree(state->src.scrub, M_PFSTATESCRUBPL);
1473         if (state->dst.scrub)
1474                 kfree(state->dst.scrub, M_PFSTATESCRUBPL);
1475
1476         /* Someday... flush the TCP segment reassembly descriptors. */
1477 }
1478
1479 int
1480 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd,
1481     u_short *reason, struct tcphdr *th, struct pf_state *state,
1482     struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback)
1483 {
1484         struct timeval uptime;
1485         u_int32_t tsval, tsecr;
1486         u_int tsval_from_last;
1487         u_int8_t hdr[60];
1488         u_int8_t *opt;
1489         int copyback = 0;
1490         int got_ts = 0;
1491
1492         KASSERT((src->scrub || dst->scrub),
1493             ("pf_normalize_tcp_statefull: src->scrub && dst->scrub!"));
1494
1495         tsval = 0;      /* avoid gcc complaint */
1496         tsecr = 0;      /* avoid gcc complaint */
1497
1498         /*
1499          * Enforce the minimum TTL seen for this connection.  Negate a common
1500          * technique to evade an intrusion detection system and confuse
1501          * firewall state code.
1502          */
1503         switch (pd->af) {
1504 #ifdef INET
1505         case AF_INET: {
1506                 if (src->scrub) {
1507                         struct ip *h = mtod(m, struct ip *);
1508                         if (h->ip_ttl > src->scrub->pfss_ttl)
1509                                 src->scrub->pfss_ttl = h->ip_ttl;
1510                         h->ip_ttl = src->scrub->pfss_ttl;
1511                 }
1512                 break;
1513         }
1514 #endif /* INET */
1515 #ifdef INET6
1516         case AF_INET6: {
1517                 if (src->scrub) {
1518                         struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1519                         if (h->ip6_hlim > src->scrub->pfss_ttl)
1520                                 src->scrub->pfss_ttl = h->ip6_hlim;
1521                         h->ip6_hlim = src->scrub->pfss_ttl;
1522                 }
1523                 break;
1524         }
1525 #endif /* INET6 */
1526         }
1527
1528         if (th->th_off > (sizeof(struct tcphdr) >> 2) &&
1529             ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) ||
1530             (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) &&
1531             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1532                 /* Diddle with TCP options */
1533                 int hlen;
1534                 opt = hdr + sizeof(struct tcphdr);
1535                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1536                 while (hlen >= TCPOLEN_TIMESTAMP) {
1537                         switch (*opt) {
1538                         case TCPOPT_EOL:        /* FALLTHROUGH */
1539                         case TCPOPT_NOP:
1540                                 opt++;
1541                                 hlen--;
1542                                 break;
1543                         case TCPOPT_TIMESTAMP:
1544                                 /* Modulate the timestamps.  Can be used for
1545                                  * NAT detection, OS uptime determination or
1546                                  * reboot detection.
1547                                  */
1548
1549                                 if (got_ts) {
1550                                         /* Huh?  Multiple timestamps!? */
1551                                         if (pf_status.debug >= PF_DEBUG_MISC) {
1552                                                 DPFPRINTF(("multiple TS??"));
1553                                                 pf_print_state(state);
1554                                                 kprintf("\n");
1555                                         }
1556                                         REASON_SET(reason, PFRES_TS);
1557                                         return (PF_DROP);
1558                                 }
1559                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1560                                         memcpy(&tsval, &opt[2],
1561                                             sizeof(u_int32_t));
1562                                         if (tsval && src->scrub &&
1563                                             (src->scrub->pfss_flags &
1564                                             PFSS_TIMESTAMP)) {
1565                                                 tsval = ntohl(tsval);
1566                                                 pf_change_a(&opt[2],
1567                                                     &th->th_sum,
1568                                                     htonl(tsval +
1569                                                     src->scrub->pfss_ts_mod),
1570                                                     0);
1571                                                 copyback = 1;
1572                                         }
1573
1574                                         /* Modulate TS reply iff valid (!0) */
1575                                         memcpy(&tsecr, &opt[6],
1576                                             sizeof(u_int32_t));
1577                                         if (tsecr && dst->scrub &&
1578                                             (dst->scrub->pfss_flags &
1579                                             PFSS_TIMESTAMP)) {
1580                                                 tsecr = ntohl(tsecr)
1581                                                     - dst->scrub->pfss_ts_mod;
1582                                                 pf_change_a(&opt[6],
1583                                                     &th->th_sum, htonl(tsecr),
1584                                                     0);
1585                                                 copyback = 1;
1586                                         }
1587                                         got_ts = 1;
1588                                 }
1589                                 /* FALLTHROUGH */
1590                         default:
1591                                 hlen -= MAX(opt[1], 2);
1592                                 opt += MAX(opt[1], 2);
1593                                 break;
1594                         }
1595                 }
1596                 if (copyback) {
1597                         /* Copyback the options, caller copys back header */
1598                         *writeback = 1;
1599                         m_copyback(m, off + sizeof(struct tcphdr),
1600                             (th->th_off << 2) - sizeof(struct tcphdr), hdr +
1601                             sizeof(struct tcphdr));
1602                 }
1603         }
1604
1605
1606         /*
1607          * Must invalidate PAWS checks on connections idle for too long.
1608          * The fastest allowed timestamp clock is 1ms.  That turns out to
1609          * be about 24 days before it wraps.  XXX Right now our lowerbound
1610          * TS echo check only works for the first 12 days of a connection
1611          * when the TS has exhausted half its 32bit space
1612          */
1613 #define TS_MAX_IDLE     (24*24*60*60)
1614 #define TS_MAX_CONN     (12*24*60*60)   /* XXX remove when better tsecr check */
1615
1616         getmicrouptime(&uptime);
1617         if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) &&
1618             (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE ||
1619             time_second - state->creation > TS_MAX_CONN))  {
1620                 if (pf_status.debug >= PF_DEBUG_MISC) {
1621                         DPFPRINTF(("src idled out of PAWS\n"));
1622                         pf_print_state(state);
1623                         kprintf("\n");
1624                 }
1625                 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS)
1626                     | PFSS_PAWS_IDLED;
1627         }
1628         if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) &&
1629             uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) {
1630                 if (pf_status.debug >= PF_DEBUG_MISC) {
1631                         DPFPRINTF(("dst idled out of PAWS\n"));
1632                         pf_print_state(state);
1633                         kprintf("\n");
1634                 }
1635                 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS)
1636                     | PFSS_PAWS_IDLED;
1637         }
1638
1639         if (got_ts && src->scrub && dst->scrub &&
1640             (src->scrub->pfss_flags & PFSS_PAWS) &&
1641             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1642                 /* Validate that the timestamps are "in-window".
1643                  * RFC1323 describes TCP Timestamp options that allow
1644                  * measurement of RTT (round trip time) and PAWS
1645                  * (protection against wrapped sequence numbers).  PAWS
1646                  * gives us a set of rules for rejecting packets on
1647                  * long fat pipes (packets that were somehow delayed
1648                  * in transit longer than the time it took to send the
1649                  * full TCP sequence space of 4Gb).  We can use these
1650                  * rules and infer a few others that will let us treat
1651                  * the 32bit timestamp and the 32bit echoed timestamp
1652                  * as sequence numbers to prevent a blind attacker from
1653                  * inserting packets into a connection.
1654                  *
1655                  * RFC1323 tells us:
1656                  *  - The timestamp on this packet must be greater than
1657                  *    or equal to the last value echoed by the other
1658                  *    endpoint.  The RFC says those will be discarded
1659                  *    since it is a dup that has already been acked.
1660                  *    This gives us a lowerbound on the timestamp.
1661                  *        timestamp >= other last echoed timestamp
1662                  *  - The timestamp will be less than or equal to
1663                  *    the last timestamp plus the time between the
1664                  *    last packet and now.  The RFC defines the max
1665                  *    clock rate as 1ms.  We will allow clocks to be
1666                  *    up to 10% fast and will allow a total difference
1667                  *    or 30 seconds due to a route change.  And this
1668                  *    gives us an upperbound on the timestamp.
1669                  *        timestamp <= last timestamp + max ticks
1670                  *    We have to be careful here.  Windows will send an
1671                  *    initial timestamp of zero and then initialize it
1672                  *    to a random value after the 3whs; presumably to
1673                  *    avoid a DoS by having to call an expensive RNG
1674                  *    during a SYN flood.  Proof MS has at least one
1675                  *    good security geek.
1676                  *
1677                  *  - The TCP timestamp option must also echo the other
1678                  *    endpoints timestamp.  The timestamp echoed is the
1679                  *    one carried on the earliest unacknowledged segment
1680                  *    on the left edge of the sequence window.  The RFC
1681                  *    states that the host will reject any echoed
1682                  *    timestamps that were larger than any ever sent.
1683                  *    This gives us an upperbound on the TS echo.
1684                  *        tescr <= largest_tsval
1685                  *  - The lowerbound on the TS echo is a little more
1686                  *    tricky to determine.  The other endpoint's echoed
1687                  *    values will not decrease.  But there may be
1688                  *    network conditions that re-order packets and
1689                  *    cause our view of them to decrease.  For now the
1690                  *    only lowerbound we can safely determine is that
1691                  *    the TS echo will never be less than the original
1692                  *    TS.  XXX There is probably a better lowerbound.
1693                  *    Remove TS_MAX_CONN with better lowerbound check.
1694                  *        tescr >= other original TS
1695                  *
1696                  * It is also important to note that the fastest
1697                  * timestamp clock of 1ms will wrap its 32bit space in
1698                  * 24 days.  So we just disable TS checking after 24
1699                  * days of idle time.  We actually must use a 12d
1700                  * connection limit until we can come up with a better
1701                  * lowerbound to the TS echo check.
1702                  */
1703                 struct timeval delta_ts;
1704                 int ts_fudge;
1705
1706
1707                 /*
1708                  * PFTM_TS_DIFF is how many seconds of leeway to allow
1709                  * a host's timestamp.  This can happen if the previous
1710                  * packet got delayed in transit for much longer than
1711                  * this packet.
1712                  */
1713                 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0)
1714                         ts_fudge = pf_default_rule.timeout[PFTM_TS_DIFF];
1715
1716
1717                 /* Calculate max ticks since the last timestamp */
1718 #define TS_MAXFREQ      1100            /* RFC max TS freq of 1Khz + 10% skew */
1719 #define TS_MICROSECS    1000000         /* microseconds per second */
1720 #ifndef timersub
1721 #define timersub(tvp, uvp, vvp)                                         \
1722         do {                                                            \
1723                 (vvp)->tv_sec = (tvp)->tv_sec - (uvp)->tv_sec;          \
1724                 (vvp)->tv_usec = (tvp)->tv_usec - (uvp)->tv_usec;       \
1725                 if ((vvp)->tv_usec < 0) {                               \
1726                         (vvp)->tv_sec--;                                \
1727                         (vvp)->tv_usec += 1000000;                      \
1728                 }                                                       \
1729         } while (0)
1730 #endif
1731
1732                 timersub(&uptime, &src->scrub->pfss_last, &delta_ts);
1733                 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ;
1734                 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ);
1735
1736
1737                 if ((src->state >= TCPS_ESTABLISHED &&
1738                     dst->state >= TCPS_ESTABLISHED) &&
1739                     (SEQ_LT(tsval, dst->scrub->pfss_tsecr) ||
1740                     SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) ||
1741                     (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) ||
1742                     SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) {
1743                         /* Bad RFC1323 implementation or an insertion attack.
1744                          *
1745                          * - Solaris 2.6 and 2.7 are known to send another ACK
1746                          *   after the FIN,FIN|ACK,ACK closing that carries
1747                          *   an old timestamp.
1748                          */
1749
1750                         DPFPRINTF(("Timestamp failed %c%c%c%c\n",
1751                             SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ',
1752                             SEQ_GT(tsval, src->scrub->pfss_tsval +
1753                             tsval_from_last) ? '1' : ' ',
1754                             SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ',
1755                             SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' '));
1756                         DPFPRINTF((" tsval: %u  tsecr: %u  +ticks: %u  "
1757                             "idle: %lus %lums\n",
1758                             tsval, tsecr, tsval_from_last, delta_ts.tv_sec,
1759                             delta_ts.tv_usec / 1000));
1760                         DPFPRINTF((" src->tsval: %u  tsecr: %u\n",
1761                             src->scrub->pfss_tsval, src->scrub->pfss_tsecr));
1762                         DPFPRINTF((" dst->tsval: %u  tsecr: %u  tsval0: %u"
1763                             "\n", dst->scrub->pfss_tsval,
1764                             dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0));
1765                         if (pf_status.debug >= PF_DEBUG_MISC) {
1766                                 pf_print_state(state);
1767                                 pf_print_flags(th->th_flags);
1768                                 kprintf("\n");
1769                         }
1770                         REASON_SET(reason, PFRES_TS);
1771                         return (PF_DROP);
1772                 }
1773
1774                 /* XXX I'd really like to require tsecr but it's optional */
1775
1776         } else if (!got_ts && (th->th_flags & TH_RST) == 0 &&
1777             ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED)
1778             || pd->p_len > 0 || (th->th_flags & TH_SYN)) &&
1779             src->scrub && dst->scrub &&
1780             (src->scrub->pfss_flags & PFSS_PAWS) &&
1781             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1782                 /* Didn't send a timestamp.  Timestamps aren't really useful
1783                  * when:
1784                  *  - connection opening or closing (often not even sent).
1785                  *    but we must not let an attacker to put a FIN on a
1786                  *    data packet to sneak it through our ESTABLISHED check.
1787                  *  - on a TCP reset.  RFC suggests not even looking at TS.
1788                  *  - on an empty ACK.  The TS will not be echoed so it will
1789                  *    probably not help keep the RTT calculation in sync and
1790                  *    there isn't as much danger when the sequence numbers
1791                  *    got wrapped.  So some stacks don't include TS on empty
1792                  *    ACKs :-(
1793                  *
1794                  * To minimize the disruption to mostly RFC1323 conformant
1795                  * stacks, we will only require timestamps on data packets.
1796                  *
1797                  * And what do ya know, we cannot require timestamps on data
1798                  * packets.  There appear to be devices that do legitimate
1799                  * TCP connection hijacking.  There are HTTP devices that allow
1800                  * a 3whs (with timestamps) and then buffer the HTTP request.
1801                  * If the intermediate device has the HTTP response cache, it
1802                  * will spoof the response but not bother timestamping its
1803                  * packets.  So we can look for the presence of a timestamp in
1804                  * the first data packet and if there, require it in all future
1805                  * packets.
1806                  */
1807
1808                 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) {
1809                         /*
1810                          * Hey!  Someone tried to sneak a packet in.  Or the
1811                          * stack changed its RFC1323 behavior?!?!
1812                          */
1813                         if (pf_status.debug >= PF_DEBUG_MISC) {
1814                                 DPFPRINTF(("Did not receive expected RFC1323 "
1815                                     "timestamp\n"));
1816                                 pf_print_state(state);
1817                                 pf_print_flags(th->th_flags);
1818                                 kprintf("\n");
1819                         }
1820                         REASON_SET(reason, PFRES_TS);
1821                         return (PF_DROP);
1822                 }
1823         }
1824
1825
1826         /*
1827          * We will note if a host sends his data packets with or without
1828          * timestamps.  And require all data packets to contain a timestamp
1829          * if the first does.  PAWS implicitly requires that all data packets be
1830          * timestamped.  But I think there are middle-man devices that hijack
1831          * TCP streams immediately after the 3whs and don't timestamp their
1832          * packets (seen in a WWW accelerator or cache).
1833          */
1834         if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags &
1835             (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) {
1836                 if (got_ts)
1837                         src->scrub->pfss_flags |= PFSS_DATA_TS;
1838                 else {
1839                         src->scrub->pfss_flags |= PFSS_DATA_NOTS;
1840                         if (pf_status.debug >= PF_DEBUG_MISC && dst->scrub &&
1841                             (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) {
1842                                 /* Don't warn if other host rejected RFC1323 */
1843                                 DPFPRINTF(("Broken RFC1323 stack did not "
1844                                     "timestamp data packet. Disabled PAWS "
1845                                     "security.\n"));
1846                                 pf_print_state(state);
1847                                 pf_print_flags(th->th_flags);
1848                                 kprintf("\n");
1849                         }
1850                 }
1851         }
1852
1853
1854         /*
1855          * Update PAWS values
1856          */
1857         if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags &
1858             (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) {
1859                 getmicrouptime(&src->scrub->pfss_last);
1860                 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) ||
1861                     (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1862                         src->scrub->pfss_tsval = tsval;
1863
1864                 if (tsecr) {
1865                         if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) ||
1866                             (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1867                                 src->scrub->pfss_tsecr = tsecr;
1868
1869                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 &&
1870                             (SEQ_LT(tsval, src->scrub->pfss_tsval0) ||
1871                             src->scrub->pfss_tsval0 == 0)) {
1872                                 /* tsval0 MUST be the lowest timestamp */
1873                                 src->scrub->pfss_tsval0 = tsval;
1874                         }
1875
1876                         /* Only fully initialized after a TS gets echoed */
1877                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0)
1878                                 src->scrub->pfss_flags |= PFSS_PAWS;
1879                 }
1880         }
1881
1882         /* I have a dream....  TCP segment reassembly.... */
1883         return (0);
1884 }
1885
1886 int
1887 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th,
1888     int off, sa_family_t af)
1889 {
1890         u_int16_t       *mss;
1891         int              thoff;
1892         int              opt, cnt, optlen = 0;
1893         int              rewrite = 0;
1894         u_char           opts[TCP_MAXOLEN];
1895         u_char          *optp = opts;
1896
1897         thoff = th->th_off << 2;
1898         cnt = thoff - sizeof(struct tcphdr);
1899
1900         if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt,
1901             NULL, NULL, af))
1902                 return (rewrite);
1903
1904         for (; cnt > 0; cnt -= optlen, optp += optlen) {
1905                 opt = optp[0];
1906                 if (opt == TCPOPT_EOL)
1907                         break;
1908                 if (opt == TCPOPT_NOP)
1909                         optlen = 1;
1910                 else {
1911                         if (cnt < 2)
1912                                 break;
1913                         optlen = optp[1];
1914                         if (optlen < 2 || optlen > cnt)
1915                                 break;
1916                 }
1917                 switch (opt) {
1918                 case TCPOPT_MAXSEG:
1919                         mss = (u_int16_t *)(optp + 2);
1920                         if ((ntohs(*mss)) > r->max_mss) {
1921                                 th->th_sum = pf_cksum_fixup(th->th_sum,
1922                                     *mss, htons(r->max_mss), 0);
1923                                 *mss = htons(r->max_mss);
1924                                 rewrite = 1;
1925                         }
1926                         break;
1927                 default:
1928                         break;
1929                 }
1930         }
1931
1932         if (rewrite)
1933                 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts);
1934
1935         return (rewrite);
1936 }