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_types.h>
  44 #include <net/bpf.h>
  45 #include <net/route.h>
  46 #include <net/pf/if_pflog.h>
  47
  48 #include <netinet/in.h>
  49 #include <netinet/in_var.h>
  50 #include <netinet/in_systm.h>
  51 #include <netinet/ip.h>
  52 #include <netinet/ip_var.h>
  53 #include <netinet/tcp.h>
  54 #include <netinet/tcp_seq.h>
  55 #include <netinet/udp.h>
  56 #include <netinet/ip_icmp.h>
  57
  58 #ifdef INET6
  59 #include <netinet/ip6.h>
  60 #endif /* INET6 */
  61
  62 #include <net/pf/pfvar.h>
  63
  64 #define PFFRAG_SEENLAST 0x0001          /* Seen the last fragment for this */
  65 #define PFFRAG_NOBUFFER 0x0002          /* Non-buffering fragment cache */
  66 #define PFFRAG_DROP     0x0004          /* Drop all fragments */
  67 #define BUFFER_FRAGMENTS(fr)    (!((fr)->fr_flags & PFFRAG_NOBUFFER))
  68
  69
  70 TAILQ_HEAD(pf_fragqueue, pf_fragment)   pf_fragqueue[MAXCPU];
  71 TAILQ_HEAD(pf_cachequeue, pf_fragment)  pf_cachequeue[MAXCPU];
  72
  73 static __inline int      pf_frag_compare(struct pf_fragment *,
  74                             struct pf_fragment *);
  75 RB_HEAD(pf_frag_tree, pf_fragment)      pf_frag_tree[MAXCPU],
  76                                         pf_cache_tree[MAXCPU];
  77 RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
  78 RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
  79
  80 /* Private prototypes */
  81 void                     pf_ip2key(struct pf_fragment *, struct ip *);
  82 void                     pf_remove_fragment(struct pf_fragment *);
  83 void                     pf_flush_fragments(void);
  84 void                     pf_free_fragment(struct pf_fragment *);
  85 struct pf_fragment      *pf_find_fragment(struct ip *, struct pf_frag_tree *);
  86 struct mbuf             *pf_reassemble(struct mbuf **, struct pf_fragment **,
  87                             struct pf_frent *, int);
  88 struct mbuf             *pf_fragcache(struct mbuf **, struct ip*,
  89                             struct pf_fragment **, int, int, int *);
  90 int                      pf_normalize_tcpopt(struct pf_rule *, struct mbuf *,
  91                             struct tcphdr *, int, sa_family_t);
  92
  93 #define DPFPRINTF(x) do {                               \
  94         if (pf_status.debug >= PF_DEBUG_MISC) {         \
  95                 kprintf("%s: ", __func__);              \
  96                 kprintf x ;                             \
  97         }                                               \
  98 } while(0)
  99
 100 static MALLOC_DEFINE(M_PFFRAGPL, "pffrag", "pf fragment pool list");
 101 static MALLOC_DEFINE(M_PFCACHEPL, "pffrcache", "pf fragment cache pool list");
 102 static MALLOC_DEFINE(M_PFFRENTPL, "pffrent", "pf frent pool list");
 103 static MALLOC_DEFINE(M_PFCENTPL, "pffrcent", "pf fragment cent pool list");
 104 static MALLOC_DEFINE(M_PFSTATESCRUBPL, "pfstatescrub", "pf state scrub pool list");
 105
 106 /* Globals */
 107 struct malloc_type       *pf_frent_pl, *pf_frag_pl, *pf_cache_pl, *pf_cent_pl;
 108 struct malloc_type       *pf_state_scrub_pl;
 109 int                      pf_nfrents, pf_ncache;
 110
 111 void
 112 pf_normalize_init(void)
 113 {
 114         int n;
 115
 116         /* XXX
 117         pool_sethiwat(&pf_frag_pl, PFFRAG_FRAG_HIWAT);
 118         pool_sethardlimit(&pf_frent_pl, PFFRAG_FRENT_HIWAT, NULL, 0);
 119         pool_sethardlimit(&pf_cache_pl, PFFRAG_FRCACHE_HIWAT, NULL, 0);
 120         pool_sethardlimit(&pf_cent_pl, PFFRAG_FRCENT_HIWAT, NULL, 0);
 121         */
 122
 123         for (n = 0; n < MAXCPU; ++n) {
 124                 TAILQ_INIT(&pf_fragqueue[n]);
 125                 TAILQ_INIT(&pf_cachequeue[n]);
 126                 RB_INIT(&pf_frag_tree[n]);
 127                 RB_INIT(&pf_cache_tree[n]);
 128         }
 129 }
 130
 131 static __inline int
 132 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b)
 133 {
 134         int     diff;
 135
 136         if ((diff = a->fr_id - b->fr_id))
 137                 return (diff);
 138         else if ((diff = a->fr_p - b->fr_p))
 139                 return (diff);
 140         else if (a->fr_src.s_addr < b->fr_src.s_addr)
 141                 return (-1);
 142         else if (a->fr_src.s_addr > b->fr_src.s_addr)
 143                 return (1);
 144         else if (a->fr_dst.s_addr < b->fr_dst.s_addr)
 145                 return (-1);
 146         else if (a->fr_dst.s_addr > b->fr_dst.s_addr)
 147                 return (1);
 148         return (0);
 149 }
 150
 151 void
 152 pf_purge_expired_fragments(void)
 153 {
 154         struct pf_fragment *frag;
 155         u_int32_t expire;
 156         int cpu = mycpu->gd_cpuid;
 157
 158         expire = time_second - pf_default_rule.timeout[PFTM_FRAG];
 159
 160         while ((frag = TAILQ_LAST(&pf_fragqueue[cpu], pf_fragqueue)) != NULL) {
 161                 KASSERT((BUFFER_FRAGMENTS(frag)),
 162                         ("BUFFER_FRAGMENTS(frag) == 0: %s", __func__));
 163                 if (frag->fr_timeout > expire)
 164                         break;
 165
 166                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 167                 pf_free_fragment(frag);
 168         }
 169
 170         while ((frag = TAILQ_LAST(&pf_cachequeue[cpu], pf_cachequeue)) != NULL) {
 171                 KASSERT((!BUFFER_FRAGMENTS(frag)),
 172                         ("BUFFER_FRAGMENTS(frag) != 0: %s", __func__));
 173                 if (frag->fr_timeout > expire)
 174                         break;
 175
 176                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 177                 pf_free_fragment(frag);
 178                 KASSERT((TAILQ_EMPTY(&pf_cachequeue[cpu]) ||
 179                     TAILQ_LAST(&pf_cachequeue[cpu], pf_cachequeue) != frag),
 180                     ("!(TAILQ_EMPTY() || TAILQ_LAST() == farg): %s",
 181                     __func__));
 182         }
 183 }
 184
 185 /*
 186  * Try to flush old fragments to make space for new ones
 187  */
 188
 189 void
 190 pf_flush_fragments(void)
 191 {
 192         struct pf_fragment *frag;
 193         int goal;
 194         int cpu = mycpu->gd_cpuid;
 195
 196         goal = pf_nfrents * 9 / 10;
 197         DPFPRINTF(("trying to free > %d frents\n",
 198             pf_nfrents - goal));
 199         while (goal < pf_nfrents) {
 200                 frag = TAILQ_LAST(&pf_fragqueue[cpu], pf_fragqueue);
 201                 if (frag == NULL)
 202                         break;
 203                 pf_free_fragment(frag);
 204         }
 205
 206
 207         goal = pf_ncache * 9 / 10;
 208         DPFPRINTF(("trying to free > %d cache entries\n",
 209             pf_ncache - goal));
 210         while (goal < pf_ncache) {
 211                 frag = TAILQ_LAST(&pf_cachequeue[cpu], pf_cachequeue);
 212                 if (frag == NULL)
 213                         break;
 214                 pf_free_fragment(frag);
 215         }
 216 }
 217
 218 /* Frees the fragments and all associated entries */
 219
 220 void
 221 pf_free_fragment(struct pf_fragment *frag)
 222 {
 223         struct pf_frent         *frent;
 224         struct pf_frcache       *frcache;
 225
 226         /* Free all fragments */
 227         if (BUFFER_FRAGMENTS(frag)) {
 228                 for (frent = LIST_FIRST(&frag->fr_queue); frent;
 229                     frent = LIST_FIRST(&frag->fr_queue)) {
 230                         LIST_REMOVE(frent, fr_next);
 231
 232                         m_freem(frent->fr_m);
 233                         kfree(frent, M_PFFRENTPL);
 234                         pf_nfrents--;
 235                 }
 236         } else {
 237                 for (frcache = LIST_FIRST(&frag->fr_cache); frcache;
 238                     frcache = LIST_FIRST(&frag->fr_cache)) {
 239                         LIST_REMOVE(frcache, fr_next);
 240
 241                         KASSERT((LIST_EMPTY(&frag->fr_cache) ||
 242                             LIST_FIRST(&frag->fr_cache)->fr_off >
 243                             frcache->fr_end),
 244                             ("! (LIST_EMPTY() || LIST_FIRST()->fr_off >"
 245                              " frcache->fr_end): %s", __func__));
 246
 247                         kfree(frcache, M_PFCENTPL);
 248                         pf_ncache--;
 249                 }
 250         }
 251
 252         pf_remove_fragment(frag);
 253 }
 254
 255 void
 256 pf_ip2key(struct pf_fragment *key, struct ip *ip)
 257 {
 258         key->fr_p = ip->ip_p;
 259         key->fr_id = ip->ip_id;
 260         key->fr_src.s_addr = ip->ip_src.s_addr;
 261         key->fr_dst.s_addr = ip->ip_dst.s_addr;
 262 }
 263
 264 struct pf_fragment *
 265 pf_find_fragment(struct ip *ip, struct pf_frag_tree *tree)
 266 {
 267         struct pf_fragment       key;
 268         struct pf_fragment      *frag;
 269         int cpu = mycpu->gd_cpuid;
 270
 271         pf_ip2key(&key, ip);
 272
 273         frag = RB_FIND(pf_frag_tree, tree, &key);
 274         if (frag != NULL) {
 275                 /* XXX Are we sure we want to update the timeout? */
 276                 frag->fr_timeout = time_second;
 277                 if (BUFFER_FRAGMENTS(frag)) {
 278                         TAILQ_REMOVE(&pf_fragqueue[cpu], frag, frag_next);
 279                         TAILQ_INSERT_HEAD(&pf_fragqueue[cpu], frag, frag_next);
 280                 } else {
 281                         TAILQ_REMOVE(&pf_cachequeue[cpu], frag, frag_next);
 282                         TAILQ_INSERT_HEAD(&pf_cachequeue[cpu], frag, frag_next);
 283                 }
 284         }
 285
 286         return (frag);
 287 }
 288
 289 /* Removes a fragment from the fragment queue and frees the fragment */
 290
 291 void
 292 pf_remove_fragment(struct pf_fragment *frag)
 293 {
 294         int cpu = mycpu->gd_cpuid;
 295
 296         if (BUFFER_FRAGMENTS(frag)) {
 297                 RB_REMOVE(pf_frag_tree, &pf_frag_tree[cpu], frag);
 298                 TAILQ_REMOVE(&pf_fragqueue[cpu], frag, frag_next);
 299                 kfree(frag, M_PFFRAGPL);
 300         } else {
 301                 RB_REMOVE(pf_frag_tree, &pf_cache_tree[cpu], frag);
 302                 TAILQ_REMOVE(&pf_cachequeue[cpu], frag, frag_next);
 303                 kfree(frag, M_PFCACHEPL);
 304         }
 305 }
 306
 307 #define FR_IP_OFF(fr)   (((fr)->fr_ip->ip_off & IP_OFFMASK) << 3)
 308 struct mbuf *
 309 pf_reassemble(struct mbuf **m0, struct pf_fragment **frag,
 310     struct pf_frent *frent, int mff)
 311 {
 312         struct mbuf     *m = *m0, *m2;
 313         struct pf_frent *frea, *next;
 314         struct pf_frent *frep = NULL;
 315         struct ip       *ip = frent->fr_ip;
 316         int             hlen = ip->ip_hl << 2;
 317         u_int16_t       off = (ip->ip_off & IP_OFFMASK) << 3;
 318         u_int16_t       ip_len = ip->ip_len - ip->ip_hl * 4;
 319         u_int16_t       max = ip_len + off;
 320         int             cpu = mycpu->gd_cpuid;
 321
 322         KASSERT((*frag == NULL || BUFFER_FRAGMENTS(*frag)),
 323             ("! (*frag == NULL || BUFFER_FRAGMENTS(*frag)): %s", __func__));
 324
 325         /* Strip off ip header */
 326         m->m_data += hlen;
 327         m->m_len -= hlen;
 328
 329         /* Create a new reassembly queue for this packet */
 330         if (*frag == NULL) {
 331                 *frag = kmalloc(sizeof(struct pf_fragment), M_PFFRAGPL, M_NOWAIT);
 332                 if (*frag == NULL) {
 333                         pf_flush_fragments();
 334                         *frag = kmalloc(sizeof(struct pf_fragment), M_PFFRAGPL, M_NOWAIT);
 335                         if (*frag == NULL)
 336                                 goto drop_fragment;
 337                 }
 338
 339                 (*frag)->fr_flags = 0;
 340                 (*frag)->fr_max = 0;
 341                 (*frag)->fr_src = frent->fr_ip->ip_src;
 342                 (*frag)->fr_dst = frent->fr_ip->ip_dst;
 343                 (*frag)->fr_p = frent->fr_ip->ip_p;
 344                 (*frag)->fr_id = frent->fr_ip->ip_id;
 345                 (*frag)->fr_timeout = time_second;
 346                 LIST_INIT(&(*frag)->fr_queue);
 347
 348                 RB_INSERT(pf_frag_tree, &pf_frag_tree[cpu], *frag);
 349                 TAILQ_INSERT_HEAD(&pf_fragqueue[cpu], *frag, frag_next);
 350
 351                 /* We do not have a previous fragment */
 352                 frep = NULL;
 353                 goto insert;
 354         }
 355
 356         /*
 357          * Find a fragment after the current one:
 358          *  - off contains the real shifted offset.
 359          */
 360         LIST_FOREACH(frea, &(*frag)->fr_queue, fr_next) {
 361                 if (FR_IP_OFF(frea) > off)
 362                         break;
 363                 frep = frea;
 364         }
 365
 366         KASSERT((frep != NULL || frea != NULL),
 367             ("!(frep != NULL || frea != NULL): %s", __func__));
 368
 369         if (frep != NULL &&
 370             FR_IP_OFF(frep) + frep->fr_ip->ip_len - frep->fr_ip->ip_hl *
 371             4 > off)
 372         {
 373                 u_int16_t       precut;
 374
 375                 precut = FR_IP_OFF(frep) + frep->fr_ip->ip_len -
 376                     frep->fr_ip->ip_hl * 4 - off;
 377                 if (precut >= ip_len)
 378                         goto drop_fragment;
 379                 m_adj(frent->fr_m, precut);
 380                 DPFPRINTF(("overlap -%d\n", precut));
 381                 /* Enforce 8 byte boundaries */
 382                 ip->ip_off = ip->ip_off + (precut >> 3);
 383                 off = (ip->ip_off & IP_OFFMASK) << 3;
 384                 ip_len -= precut;
 385                 ip->ip_len = ip_len;
 386         }
 387
 388         for (; frea != NULL && ip_len + off > FR_IP_OFF(frea);
 389             frea = next)
 390         {
 391                 u_int16_t       aftercut;
 392
 393                 aftercut = ip_len + off - FR_IP_OFF(frea);
 394                 DPFPRINTF(("adjust overlap %d\n", aftercut));
 395                 if (aftercut < frea->fr_ip->ip_len - frea->fr_ip->ip_hl
 396                     * 4)
 397                 {
 398                         frea->fr_ip->ip_len =
 399                             frea->fr_ip->ip_len - aftercut;
 400                         frea->fr_ip->ip_off = frea->fr_ip->ip_off +
 401                             (aftercut >> 3);
 402                         m_adj(frea->fr_m, aftercut);
 403                         break;
 404                 }
 405
 406                 /* This fragment is completely overlapped, lose it */
 407                 next = LIST_NEXT(frea, fr_next);
 408                 m_freem(frea->fr_m);
 409                 LIST_REMOVE(frea, fr_next);
 410                 kfree(frea, M_PFFRENTPL);
 411                 pf_nfrents--;
 412         }
 413
 414  insert:
 415         /* Update maximum data size */
 416         if ((*frag)->fr_max < max)
 417                 (*frag)->fr_max = max;
 418         /* This is the last segment */
 419         if (!mff)
 420                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
 421
 422         if (frep == NULL)
 423                 LIST_INSERT_HEAD(&(*frag)->fr_queue, frent, fr_next);
 424         else
 425                 LIST_INSERT_AFTER(frep, frent, fr_next);
 426
 427         /* Check if we are completely reassembled */
 428         if (!((*frag)->fr_flags & PFFRAG_SEENLAST))
 429                 return (NULL);
 430
 431         /* Check if we have all the data */
 432         off = 0;
 433         for (frep = LIST_FIRST(&(*frag)->fr_queue); frep; frep = next) {
 434                 next = LIST_NEXT(frep, fr_next);
 435
 436                 off += frep->fr_ip->ip_len - frep->fr_ip->ip_hl * 4;
 437                 if (off < (*frag)->fr_max &&
 438                     (next == NULL || FR_IP_OFF(next) != off))
 439                 {
 440                         DPFPRINTF(("missing fragment at %d, next %d, max %d\n",
 441                             off, next == NULL ? -1 : FR_IP_OFF(next),
 442                             (*frag)->fr_max));
 443                         return (NULL);
 444                 }
 445         }
 446         DPFPRINTF(("%d < %d?\n", off, (*frag)->fr_max));
 447         if (off < (*frag)->fr_max)
 448                 return (NULL);
 449
 450         /* We have all the data */
 451         frent = LIST_FIRST(&(*frag)->fr_queue);
 452         KASSERT((frent != NULL), ("frent == NULL: %s", __func__));
 453         if ((frent->fr_ip->ip_hl << 2) + off > IP_MAXPACKET) {
 454                 DPFPRINTF(("drop: too big: %d\n", off));
 455                 pf_free_fragment(*frag);
 456                 *frag = NULL;
 457                 return (NULL);
 458         }
 459         next = LIST_NEXT(frent, fr_next);
 460
 461         /* Magic from ip_input */
 462         ip = frent->fr_ip;
 463         m = frent->fr_m;
 464         m2 = m->m_next;
 465         m->m_next = NULL;
 466         m_cat(m, m2);
 467         kfree(frent, M_PFFRENTPL);
 468         pf_nfrents--;
 469         for (frent = next; frent != NULL; frent = next) {
 470                 next = LIST_NEXT(frent, fr_next);
 471
 472                 m2 = frent->fr_m;
 473                 kfree(frent, M_PFFRENTPL);
 474                 pf_nfrents--;
 475                 m_cat(m, m2);
 476         }
 477
 478         ip->ip_src = (*frag)->fr_src;
 479         ip->ip_dst = (*frag)->fr_dst;
 480
 481         /* Remove from fragment queue */
 482         pf_remove_fragment(*frag);
 483         *frag = NULL;
 484
 485         hlen = ip->ip_hl << 2;
 486         ip->ip_len = off + hlen;
 487         m->m_len += hlen;
 488         m->m_data -= hlen;
 489
 490         /* some debugging cruft by sklower, below, will go away soon */
 491         /* XXX this should be done elsewhere */
 492         if (m->m_flags & M_PKTHDR) {
 493                 int plen = 0;
 494                 for (m2 = m; m2; m2 = m2->m_next)
 495                         plen += m2->m_len;
 496                 m->m_pkthdr.len = plen;
 497         }
 498
 499         DPFPRINTF(("complete: %p(%d)\n", m, ip->ip_len));
 500         return (m);
 501
 502  drop_fragment:
 503         /* Oops - fail safe - drop packet */
 504         kfree(frent, M_PFFRENTPL);
 505         pf_nfrents--;
 506         m_freem(m);
 507         return (NULL);
 508 }
 509
 510 struct mbuf *
 511 pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff,
 512     int drop, int *nomem)
 513 {
 514         struct mbuf     *m = *m0;
 515         struct pf_frcache *frp, *fra, *cur = NULL;
 516         int             ip_len = h->ip_len - (h->ip_hl << 2);
 517         u_int16_t       off = h->ip_off << 3;
 518         u_int16_t       max = ip_len + off;
 519         int             hosed = 0;
 520         int             cpu = mycpu->gd_cpuid;
 521
 522         KASSERT((*frag == NULL || !BUFFER_FRAGMENTS(*frag)),
 523             ("!(*frag == NULL || !BUFFER_FRAGMENTS(*frag)): %s", __func__));
 524
 525         /* Create a new range queue for this packet */
 526         if (*frag == NULL) {
 527                 *frag = kmalloc(sizeof(struct pf_fragment), M_PFCACHEPL, M_NOWAIT);
 528                 if (*frag == NULL) {
 529                         pf_flush_fragments();
 530                         *frag = kmalloc(sizeof(struct pf_fragment), M_PFCACHEPL, M_NOWAIT);
 531                         if (*frag == NULL)
 532                                 goto no_mem;
 533                 }
 534
 535                 /* Get an entry for the queue */
 536                 cur = kmalloc(sizeof(struct pf_frcache), M_PFCENTPL, M_NOWAIT);
 537                 if (cur == NULL) {
 538                         kfree(*frag, M_PFCACHEPL);
 539                         *frag = NULL;
 540                         goto no_mem;
 541                 }
 542                 pf_ncache++;
 543
 544                 (*frag)->fr_flags = PFFRAG_NOBUFFER;
 545                 (*frag)->fr_max = 0;
 546                 (*frag)->fr_src = h->ip_src;
 547                 (*frag)->fr_dst = h->ip_dst;
 548                 (*frag)->fr_p = h->ip_p;
 549                 (*frag)->fr_id = h->ip_id;
 550                 (*frag)->fr_timeout = time_second;
 551
 552                 cur->fr_off = off;
 553                 cur->fr_end = max;
 554                 LIST_INIT(&(*frag)->fr_cache);
 555                 LIST_INSERT_HEAD(&(*frag)->fr_cache, cur, fr_next);
 556
 557                 RB_INSERT(pf_frag_tree, &pf_cache_tree[cpu], *frag);
 558                 TAILQ_INSERT_HEAD(&pf_cachequeue[cpu], *frag, frag_next);
 559
 560                 DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max));
 561
 562                 goto pass;
 563         }
 564
 565         /*
 566          * Find a fragment after the current one:
 567          *  - off contains the real shifted offset.
 568          */
 569         frp = NULL;
 570         LIST_FOREACH(fra, &(*frag)->fr_cache, fr_next) {
 571                 if (fra->fr_off > off)
 572                         break;
 573                 frp = fra;
 574         }
 575
 576         KASSERT((frp != NULL || fra != NULL),
 577             ("!(frp != NULL || fra != NULL): %s", __func__));
 578
 579         if (frp != NULL) {
 580                 int     precut;
 581
 582                 precut = frp->fr_end - off;
 583                 if (precut >= ip_len) {
 584                         /* Fragment is entirely a duplicate */
 585                         DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n",
 586                             h->ip_id, frp->fr_off, frp->fr_end, off, max));
 587                         goto drop_fragment;
 588                 }
 589                 if (precut == 0) {
 590                         /* They are adjacent.  Fixup cache entry */
 591                         DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n",
 592                             h->ip_id, frp->fr_off, frp->fr_end, off, max));
 593                         frp->fr_end = max;
 594                 } else if (precut > 0) {
 595                         /* The first part of this payload overlaps with a
 596                          * fragment that has already been passed.
 597                          * Need to trim off the first part of the payload.
 598                          * But to do so easily, we need to create another
 599                          * mbuf to throw the original header into.
 600                          */
 601
 602                         DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n",
 603                             h->ip_id, precut, frp->fr_off, frp->fr_end, off,
 604                             max));
 605
 606                         off += precut;
 607                         max -= precut;
 608                         /* Update the previous frag to encompass this one */
 609                         frp->fr_end = max;
 610
 611                         if (!drop) {
 612                                 /* XXX Optimization opportunity
 613                                  * This is a very heavy way to trim the payload.
 614                                  * we could do it much faster by diddling mbuf
 615                                  * internals but that would be even less legible
 616                                  * than this mbuf magic.  For my next trick,
 617                                  * I'll pull a rabbit out of my laptop.
 618                                  */
 619                                 *m0 = m_dup(m, M_NOWAIT);
 620                                 /* From KAME Project : We have missed this! */
 621                                 m_adj(*m0, (h->ip_hl << 2) -
 622                                     (*m0)->m_pkthdr.len);
 623                                 if (*m0 == NULL)
 624                                         goto no_mem;
 625                                 KASSERT(((*m0)->m_next == NULL),
 626                                     ("(*m0)->m_next != NULL: %s",
 627                                     __func__));
 628                                 m_adj(m, precut + (h->ip_hl << 2));
 629                                 m_cat(*m0, m);
 630                                 m = *m0;
 631                                 if (m->m_flags & M_PKTHDR) {
 632                                         int plen = 0;
 633                                         struct mbuf *t;
 634                                         for (t = m; t; t = t->m_next)
 635                                                 plen += t->m_len;
 636                                         m->m_pkthdr.len = plen;
 637                                 }
 638
 639
 640                                 h = mtod(m, struct ip *);
 641
 642                                 KASSERT(((int)m->m_len ==
 643                                     h->ip_len - precut),
 644                                     ("m->m_len != h->ip_len - precut: %s",
 645                                     __func__));
 646                                 h->ip_off = h->ip_off +
 647                                     (precut >> 3);
 648                                 h->ip_len = h->ip_len - precut;
 649                         } else {
 650                                 hosed++;
 651                         }
 652                 } else {
 653                         /* There is a gap between fragments */
 654
 655                         DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n",
 656                             h->ip_id, -precut, frp->fr_off, frp->fr_end, off,
 657                             max));
 658
 659                         cur = kmalloc(sizeof(struct pf_frcache), M_PFCENTPL, M_NOWAIT);
 660                         if (cur == NULL)
 661                                 goto no_mem;
 662                         pf_ncache++;
 663
 664                         cur->fr_off = off;
 665                         cur->fr_end = max;
 666                         LIST_INSERT_AFTER(frp, cur, fr_next);
 667                 }
 668         }
 669
 670         if (fra != NULL) {
 671                 int     aftercut;
 672                 int     merge = 0;
 673
 674                 aftercut = max - fra->fr_off;
 675                 if (aftercut == 0) {
 676                         /* Adjacent fragments */
 677                         DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n",
 678                             h->ip_id, off, max, fra->fr_off, fra->fr_end));
 679                         fra->fr_off = off;
 680                         merge = 1;
 681                 } else if (aftercut > 0) {
 682                         /* Need to chop off the tail of this fragment */
 683                         DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n",
 684                             h->ip_id, aftercut, off, max, fra->fr_off,
 685                             fra->fr_end));
 686                         fra->fr_off = off;
 687                         max -= aftercut;
 688
 689                         merge = 1;
 690
 691                         if (!drop) {
 692                                 m_adj(m, -aftercut);
 693                                 if (m->m_flags & M_PKTHDR) {
 694                                         int plen = 0;
 695                                         struct mbuf *t;
 696                                         for (t = m; t; t = t->m_next)
 697                                                 plen += t->m_len;
 698                                         m->m_pkthdr.len = plen;
 699                                 }
 700                                 h = mtod(m, struct ip *);
 701                                 KASSERT(((int)m->m_len == h->ip_len - aftercut),
 702                                     ("m->m_len != h->ip_len - aftercut: %s",
 703                                     __func__));
 704                                 h->ip_len = h->ip_len - aftercut;
 705                         } else {
 706                                 hosed++;
 707                         }
 708                 } else if (frp == NULL) {
 709                         /* There is a gap between fragments */
 710                         DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n",
 711                             h->ip_id, -aftercut, off, max, fra->fr_off,
 712                             fra->fr_end));
 713
 714                         cur = kmalloc(sizeof(struct pf_frcache), M_PFCENTPL, M_NOWAIT);
 715                         if (cur == NULL)
 716                                 goto no_mem;
 717                         pf_ncache++;
 718
 719                         cur->fr_off = off;
 720                         cur->fr_end = max;
 721                         LIST_INSERT_BEFORE(fra, cur, fr_next);
 722                 }
 723
 724
 725                 /* Need to glue together two separate fragment descriptors */
 726                 if (merge) {
 727                         if (cur && fra->fr_off <= cur->fr_end) {
 728                                 /* Need to merge in a previous 'cur' */
 729                                 DPFPRINTF(("fragcache[%d]: adjacent(merge "
 730                                     "%d-%d) %d-%d (%d-%d)\n",
 731                                     h->ip_id, cur->fr_off, cur->fr_end, off,
 732                                     max, fra->fr_off, fra->fr_end));
 733                                 fra->fr_off = cur->fr_off;
 734                                 LIST_REMOVE(cur, fr_next);
 735                                 kfree(cur, M_PFCENTPL);
 736                                 pf_ncache--;
 737                                 cur = NULL;
 738
 739                         } else if (frp && fra->fr_off <= frp->fr_end) {
 740                                 /* Need to merge in a modified 'frp' */
 741                                 KASSERT((cur == NULL), ("cur != NULL: %s",
 742                                     __func__));
 743                                 DPFPRINTF(("fragcache[%d]: adjacent(merge "
 744                                     "%d-%d) %d-%d (%d-%d)\n",
 745                                     h->ip_id, frp->fr_off, frp->fr_end, off,
 746                                     max, fra->fr_off, fra->fr_end));
 747                                 fra->fr_off = frp->fr_off;
 748                                 LIST_REMOVE(frp, fr_next);
 749                                 kfree(frp, M_PFCENTPL);
 750                                 pf_ncache--;
 751                                 frp = NULL;
 752
 753                         }
 754                 }
 755         }
 756
 757         if (hosed) {
 758                 /*
 759                  * We must keep tracking the overall fragment even when
 760                  * we're going to drop it anyway so that we know when to
 761                  * free the overall descriptor.  Thus we drop the frag late.
 762                  */
 763                 goto drop_fragment;
 764         }
 765
 766
 767  pass:
 768         /* Update maximum data size */
 769         if ((*frag)->fr_max < max)
 770                 (*frag)->fr_max = max;
 771
 772         /* This is the last segment */
 773         if (!mff)
 774                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
 775
 776         /* Check if we are completely reassembled */
 777         if (((*frag)->fr_flags & PFFRAG_SEENLAST) &&
 778             LIST_FIRST(&(*frag)->fr_cache)->fr_off == 0 &&
 779             LIST_FIRST(&(*frag)->fr_cache)->fr_end == (*frag)->fr_max) {
 780                 /* Remove from fragment queue */
 781                 DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id,
 782                     (*frag)->fr_max));
 783                 pf_free_fragment(*frag);
 784                 *frag = NULL;
 785         }
 786
 787         return (m);
 788
 789  no_mem:
 790         *nomem = 1;
 791
 792         /* Still need to pay attention to !IP_MF */
 793         if (!mff && *frag != NULL)
 794                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
 795
 796         m_freem(m);
 797         return (NULL);
 798
 799  drop_fragment:
 800
 801         /* Still need to pay attention to !IP_MF */
 802         if (!mff && *frag != NULL)
 803                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
 804
 805         if (drop) {
 806                 /* This fragment has been deemed bad.  Don't reass */
 807                 if (((*frag)->fr_flags & PFFRAG_DROP) == 0)
 808                         DPFPRINTF(("fragcache[%d]: dropping overall fragment\n",
 809                             h->ip_id));
 810                 (*frag)->fr_flags |= PFFRAG_DROP;
 811         }
 812
 813         m_freem(m);
 814         return (NULL);
 815 }
 816
 817 int
 818 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason,
 819     struct pf_pdesc *pd)
 820 {
 821         struct mbuf     *m = *m0;
 822         struct pf_rule  *r;
 823         struct pf_frent *frent;
 824         struct pf_fragment *frag = NULL;
 825         struct ip       *h = mtod(m, struct ip *);
 826         int             mff = (h->ip_off & IP_MF);
 827         int             hlen = h->ip_hl << 2;
 828         u_int16_t       fragoff = (h->ip_off & IP_OFFMASK) << 3;
 829         u_int16_t       max;
 830         int             ip_len;
 831         int             tag = -1;
 832         int             cpu = mycpu->gd_cpuid;
 833
 834         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
 835         while (r != NULL) {
 836                 r->evaluations++;
 837                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
 838                         r = r->skip[PF_SKIP_IFP].ptr;
 839                 else if (r->direction && r->direction != dir)
 840                         r = r->skip[PF_SKIP_DIR].ptr;
 841                 else if (r->af && r->af != AF_INET)
 842                         r = r->skip[PF_SKIP_AF].ptr;
 843                 else if (r->proto && r->proto != h->ip_p)
 844                         r = r->skip[PF_SKIP_PROTO].ptr;
 845                 else if (PF_MISMATCHAW(&r->src.addr,
 846                     (struct pf_addr *)&h->ip_src.s_addr, AF_INET,
 847                     r->src.neg, kif))
 848                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
 849                 else if (PF_MISMATCHAW(&r->dst.addr,
 850                     (struct pf_addr *)&h->ip_dst.s_addr, AF_INET,
 851                     r->dst.neg, NULL))
 852                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
 853                 else if (r->match_tag && !pf_match_tag(m, r, &tag))
 854                         r = TAILQ_NEXT(r, entries);
 855                 else
 856                         break;
 857         }
 858
 859         if (r == NULL || r->action == PF_NOSCRUB)
 860                 return (PF_PASS);
 861         else {
 862                 r->packets[dir == PF_OUT]++;
 863                 r->bytes[dir == PF_OUT] += pd->tot_len;
 864         }
 865
 866         /* Check for illegal packets */
 867         if (hlen < (int)sizeof(struct ip))
 868                 goto drop;
 869
 870         if (hlen > h->ip_len)
 871                 goto drop;
 872
 873         /* Clear IP_DF if the rule uses the no-df option */
 874         if (r->rule_flag & PFRULE_NODF && h->ip_off & IP_DF) {
 875                 u_int16_t ip_off = h->ip_off;
 876
 877                 h->ip_off &= ~IP_DF;
 878                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
 879         }
 880
 881         /* We will need other tests here */
 882         if (!fragoff && !mff)
 883                 goto no_fragment;
 884
 885         /* We're dealing with a fragment now. Don't allow fragments
 886          * with IP_DF to enter the cache. If the flag was cleared by
 887          * no-df above, fine. Otherwise drop it.
 888          */
 889         if (h->ip_off & IP_DF) {
 890                 DPFPRINTF(("IP_DF\n"));
 891                 goto bad;
 892         }
 893
 894         ip_len = h->ip_len - hlen;
 895
 896         /* All fragments are 8 byte aligned */
 897         if (mff && (ip_len & 0x7)) {
 898                 DPFPRINTF(("mff and %d\n", ip_len));
 899                 goto bad;
 900         }
 901
 902         /* Respect maximum length */
 903         if (fragoff + ip_len > IP_MAXPACKET) {
 904                 DPFPRINTF(("max packet %d\n", fragoff + ip_len));
 905                 goto bad;
 906         }
 907         max = fragoff + ip_len;
 908
 909         if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) {
 910                 /* Fully buffer all of the fragments */
 911
 912                 frag = pf_find_fragment(h, &pf_frag_tree[cpu]);
 913
 914                 /* Check if we saw the last fragment already */
 915                 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
 916                     max > frag->fr_max)
 917                         goto bad;
 918
 919                 /* Get an entry for the fragment queue */
 920                 frent = kmalloc(sizeof(struct pf_frent), M_PFFRENTPL, M_NOWAIT);
 921                 if (frent == NULL) {
 922                         REASON_SET(reason, PFRES_MEMORY);
 923                         return (PF_DROP);
 924                 }
 925                 pf_nfrents++;
 926                 frent->fr_ip = h;
 927                 frent->fr_m = m;
 928
 929                 /* Might return a completely reassembled mbuf, or NULL */
 930                 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
 931                 *m0 = m = pf_reassemble(m0, &frag, frent, mff);
 932
 933                 if (m == NULL)
 934                         return (PF_DROP);
 935
 936                 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
 937                         goto drop;
 938
 939                 h = mtod(m, struct ip *);
 940         } else {
 941                 /* non-buffering fragment cache (drops or masks overlaps) */
 942                 int     nomem = 0;
 943
 944                 if (dir == PF_OUT && m->m_pkthdr.pf.flags & PF_TAG_FRAGCACHE) {
 945                         /*
 946                          * Already passed the fragment cache in the
 947                          * input direction.  If we continued, it would
 948                          * appear to be a dup and would be dropped.
 949                          */
 950                         goto fragment_pass;
 951                 }
 952
 953                 frag = pf_find_fragment(h, &pf_cache_tree[cpu]);
 954
 955                 /* Check if we saw the last fragment already */
 956                 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
 957                     max > frag->fr_max) {
 958                         if (r->rule_flag & PFRULE_FRAGDROP)
 959                                 frag->fr_flags |= PFFRAG_DROP;
 960                         goto bad;
 961                 }
 962
 963                 *m0 = m = pf_fragcache(m0, h, &frag, mff,
 964                     (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem);
 965                 if (m == NULL) {
 966                         if (nomem)
 967                                 goto no_mem;
 968                         goto drop;
 969                 }
 970
 971                 if (dir == PF_IN)
 972                         m->m_pkthdr.pf.flags |= PF_TAG_FRAGCACHE;
 973
 974                 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
 975                         goto drop;
 976                 goto fragment_pass;
 977         }
 978
 979  no_fragment:
 980         /* At this point, only IP_DF is allowed in ip_off */
 981         if (h->ip_off & ~IP_DF) {
 982                 u_int16_t ip_off = h->ip_off;
 983
 984                 h->ip_off &= IP_DF;
 985                 h->ip_sum = pf_cksum_fixup(h->ip_sum, htons(ip_off), htons(h->ip_off), 0);
 986         }
 987
 988         /* Enforce a minimum ttl, may cause endless packet loops */
 989         if (r->min_ttl && h->ip_ttl < r->min_ttl) {
 990                 u_int16_t ip_ttl = h->ip_ttl;
 991
 992                 h->ip_ttl = r->min_ttl;
 993                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
 994         }
 995
 996         /* Enforce tos */
 997         if (r->rule_flag & PFRULE_SET_TOS) {
 998                 u_int16_t       ov, nv;
 999
1000                 ov = *(u_int16_t *)h;
1001                 h->ip_tos = r->set_tos;
1002                 nv = *(u_int16_t *)h;
1003
1004                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0);
1005         }
1006
1007         if (r->rule_flag & PFRULE_RANDOMID) {
1008                 u_int16_t ip_id = h->ip_id;
1009
1010                 h->ip_id = ip_randomid();
1011                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0);
1012         }
1013         if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0)
1014                 pd->flags |= PFDESC_IP_REAS;
1015
1016         return (PF_PASS);
1017
1018  fragment_pass:
1019         /* Enforce a minimum ttl, may cause endless packet loops */
1020         if (r->min_ttl && h->ip_ttl < r->min_ttl) {
1021                 u_int16_t ip_ttl = h->ip_ttl;
1022
1023                 h->ip_ttl = r->min_ttl;
1024                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
1025         }
1026         /* Enforce tos */
1027         if (r->rule_flag & PFRULE_SET_TOS) {
1028                 u_int16_t       ov, nv;
1029
1030                 ov = *(u_int16_t *)h;
1031                 h->ip_tos = r->set_tos;
1032                 nv = *(u_int16_t *)h;
1033
1034                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0);
1035         }
1036         if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0)
1037                 pd->flags |= PFDESC_IP_REAS;
1038         return (PF_PASS);
1039
1040  no_mem:
1041         REASON_SET(reason, PFRES_MEMORY);
1042         if (r != NULL && r->log)
1043                 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL, pd);
1044         return (PF_DROP);
1045
1046  drop:
1047         REASON_SET(reason, PFRES_NORM);
1048         if (r != NULL && r->log)
1049                 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL, pd);
1050         return (PF_DROP);
1051
1052  bad:
1053         DPFPRINTF(("dropping bad fragment\n"));
1054
1055         /* Free associated fragments */
1056         if (frag != NULL)
1057                 pf_free_fragment(frag);
1058
1059         REASON_SET(reason, PFRES_FRAG);
1060         if (r != NULL && r->log)
1061                 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL, pd);
1062
1063         return (PF_DROP);
1064 }
1065
1066 #ifdef INET6
1067 int
1068 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif,
1069     u_short *reason, struct pf_pdesc *pd)
1070 {
1071         struct mbuf             *m = *m0;
1072         struct pf_rule          *r;
1073         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
1074         int                      off;
1075         struct ip6_ext           ext;
1076         struct ip6_opt           opt;
1077         struct ip6_opt_jumbo     jumbo;
1078         struct ip6_frag          frag;
1079         u_int32_t                jumbolen = 0, plen;
1080         u_int16_t                fragoff = 0;
1081         int                      optend;
1082         int                      ooff;
1083         u_int8_t                 proto;
1084         int                      terminal;
1085
1086         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1087         while (r != NULL) {
1088                 r->evaluations++;
1089                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1090                         r = r->skip[PF_SKIP_IFP].ptr;
1091                 else if (r->direction && r->direction != dir)
1092                         r = r->skip[PF_SKIP_DIR].ptr;
1093                 else if (r->af && r->af != AF_INET6)
1094                         r = r->skip[PF_SKIP_AF].ptr;
1095 #if 0 /* header chain! */
1096                 else if (r->proto && r->proto != h->ip6_nxt)
1097                         r = r->skip[PF_SKIP_PROTO].ptr;
1098 #endif
1099                 else if (PF_MISMATCHAW(&r->src.addr,
1100                     (struct pf_addr *)&h->ip6_src, AF_INET6,
1101                     r->src.neg, kif))
1102                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1103                 else if (PF_MISMATCHAW(&r->dst.addr,
1104                     (struct pf_addr *)&h->ip6_dst, AF_INET6,
1105                     r->dst.neg, NULL))
1106                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1107                 else
1108                         break;
1109         }
1110
1111         if (r == NULL || r->action == PF_NOSCRUB)
1112                 return (PF_PASS);
1113         else {
1114                 r->packets[dir == PF_OUT]++;
1115                 r->bytes[dir == PF_OUT] += pd->tot_len;
1116         }
1117
1118         /* Check for illegal packets */
1119         if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len)
1120                 goto drop;
1121
1122         off = sizeof(struct ip6_hdr);
1123         proto = h->ip6_nxt;
1124         terminal = 0;
1125         do {
1126                 switch (proto) {
1127                 case IPPROTO_FRAGMENT:
1128                         goto fragment;
1129                         break;
1130                 case IPPROTO_AH:
1131                 case IPPROTO_ROUTING:
1132                 case IPPROTO_DSTOPTS:
1133                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1134                             NULL, AF_INET6))
1135                                 goto shortpkt;
1136                         if (proto == IPPROTO_AH)
1137                                 off += (ext.ip6e_len + 2) * 4;
1138                         else
1139                                 off += (ext.ip6e_len + 1) * 8;
1140                         proto = ext.ip6e_nxt;
1141                         break;
1142                 case IPPROTO_HOPOPTS:
1143                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1144                             NULL, AF_INET6))
1145                                 goto shortpkt;
1146                         optend = off + (ext.ip6e_len + 1) * 8;
1147                         ooff = off + sizeof(ext);
1148                         do {
1149                                 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type,
1150                                     sizeof(opt.ip6o_type), NULL, NULL,
1151                                     AF_INET6))
1152                                         goto shortpkt;
1153                                 if (opt.ip6o_type == IP6OPT_PAD1) {
1154                                         ooff++;
1155                                         continue;
1156                                 }
1157                                 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt),
1158                                     NULL, NULL, AF_INET6))
1159                                         goto shortpkt;
1160                                 if (ooff + sizeof(opt) + opt.ip6o_len > optend)
1161                                         goto drop;
1162                                 switch (opt.ip6o_type) {
1163                                 case IP6OPT_JUMBO:
1164                                         if (h->ip6_plen != 0)
1165                                                 goto drop;
1166                                         if (!pf_pull_hdr(m, ooff, &jumbo,
1167                                             sizeof(jumbo), NULL, NULL,
1168                                             AF_INET6))
1169                                                 goto shortpkt;
1170                                         memcpy(&jumbolen, jumbo.ip6oj_jumbo_len,
1171                                             sizeof(jumbolen));
1172                                         jumbolen = ntohl(jumbolen);
1173                                         if (jumbolen <= IPV6_MAXPACKET)
1174                                                 goto drop;
1175                                         if (sizeof(struct ip6_hdr) + jumbolen !=
1176                                             m->m_pkthdr.len)
1177                                                 goto drop;
1178                                         break;
1179                                 default:
1180                                         break;
1181                                 }
1182                                 ooff += sizeof(opt) + opt.ip6o_len;
1183                         } while (ooff < optend);
1184
1185                         off = optend;
1186                         proto = ext.ip6e_nxt;
1187                         break;
1188                 default:
1189                         terminal = 1;
1190                         break;
1191                 }
1192         } while (!terminal);
1193
1194         /* jumbo payload option must be present, or plen > 0 */
1195         if (ntohs(h->ip6_plen) == 0)
1196                 plen = jumbolen;
1197         else
1198                 plen = ntohs(h->ip6_plen);
1199         if (plen == 0)
1200                 goto drop;
1201         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1202                 goto shortpkt;
1203
1204         /* Enforce a minimum ttl, may cause endless packet loops */
1205         if (r->min_ttl && h->ip6_hlim < r->min_ttl)
1206                 h->ip6_hlim = r->min_ttl;
1207
1208         return (PF_PASS);
1209
1210  fragment:
1211         if (ntohs(h->ip6_plen) == 0 || jumbolen)
1212                 goto drop;
1213         plen = ntohs(h->ip6_plen);
1214
1215         if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6))
1216                 goto shortpkt;
1217         fragoff = ntohs(frag.ip6f_offlg & IP6F_OFF_MASK);
1218         if (fragoff + (plen - off - sizeof(frag)) > IPV6_MAXPACKET)
1219                 goto badfrag;
1220
1221         /* do something about it */
1222         /* remember to set pd->flags |= PFDESC_IP_REAS */
1223         return (PF_PASS);
1224
1225  shortpkt:
1226         REASON_SET(reason, PFRES_SHORT);
1227         if (r != NULL && r->log)
1228                 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL, pd);
1229         return (PF_DROP);
1230
1231  drop:
1232         REASON_SET(reason, PFRES_NORM);
1233         if (r != NULL && r->log)
1234                 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL, pd);
1235         return (PF_DROP);
1236
1237  badfrag:
1238         REASON_SET(reason, PFRES_FRAG);
1239         if (r != NULL && r->log)
1240                 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL, pd);
1241         return (PF_DROP);
1242 }
1243 #endif /* INET6 */
1244
1245 int
1246 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff,
1247     int off, void *h, struct pf_pdesc *pd)
1248 {
1249         struct pf_rule  *r, *rm = NULL;
1250         struct tcphdr   *th = pd->hdr.tcp;
1251         int              rewrite = 0;
1252         u_short          reason;
1253         u_int8_t         flags;
1254         sa_family_t      af = pd->af;
1255
1256         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1257         while (r != NULL) {
1258                 r->evaluations++;
1259                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1260                         r = r->skip[PF_SKIP_IFP].ptr;
1261                 else if (r->direction && r->direction != dir)
1262                         r = r->skip[PF_SKIP_DIR].ptr;
1263                 else if (r->af && r->af != af)
1264                         r = r->skip[PF_SKIP_AF].ptr;
1265                 else if (r->proto && r->proto != pd->proto)
1266                         r = r->skip[PF_SKIP_PROTO].ptr;
1267                 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af,
1268                     r->src.neg, kif))
1269                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1270                 else if (r->src.port_op && !pf_match_port(r->src.port_op,
1271                             r->src.port[0], r->src.port[1], th->th_sport))
1272                         r = r->skip[PF_SKIP_SRC_PORT].ptr;
1273                 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af,
1274                     r->dst.neg, NULL))
1275                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1276                 else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
1277                             r->dst.port[0], r->dst.port[1], th->th_dport))
1278                         r = r->skip[PF_SKIP_DST_PORT].ptr;
1279                 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match(
1280                             pf_osfp_fingerprint(pd, m, off, th),
1281                             r->os_fingerprint))
1282                         r = TAILQ_NEXT(r, entries);
1283                 else {
1284                         rm = r;
1285                         break;
1286                 }
1287         }
1288
1289         if (rm == NULL || rm->action == PF_NOSCRUB)
1290                 return (PF_PASS);
1291         else {
1292                 r->packets[dir == PF_OUT]++;
1293                 r->bytes[dir == PF_OUT] += pd->tot_len;
1294         }
1295
1296         if (rm->rule_flag & PFRULE_REASSEMBLE_TCP)
1297                 pd->flags |= PFDESC_TCP_NORM;
1298
1299         flags = th->th_flags;
1300         if (flags & TH_SYN) {
1301                 /* Illegal packet */
1302                 if (flags & TH_RST)
1303                         goto tcp_drop;
1304
1305                 if (flags & TH_FIN)
1306                         flags &= ~TH_FIN;
1307         } else {
1308                 /* Illegal packet */
1309                 if (!(flags & (TH_ACK|TH_RST)))
1310                         goto tcp_drop;
1311         }
1312
1313         if (!(flags & TH_ACK)) {
1314                 /* These flags are only valid if ACK is set */
1315                 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG))
1316                         goto tcp_drop;
1317         }
1318
1319         /* Check for illegal header length */
1320         if (th->th_off < (sizeof(struct tcphdr) >> 2))
1321                 goto tcp_drop;
1322
1323         /* If flags changed, or reserved data set, then adjust */
1324         if (flags != th->th_flags || th->th_x2 != 0) {
1325                 u_int16_t       ov, nv;
1326
1327                 ov = *(u_int16_t *)(&th->th_ack + 1);
1328                 th->th_flags = flags;
1329                 th->th_x2 = 0;
1330                 nv = *(u_int16_t *)(&th->th_ack + 1);
1331
1332                 th->th_sum = pf_cksum_fixup(th->th_sum, ov, nv, 0);
1333                 rewrite = 1;
1334         }
1335
1336         /* Remove urgent pointer, if TH_URG is not set */
1337         if (!(flags & TH_URG) && th->th_urp) {
1338                 th->th_sum = pf_cksum_fixup(th->th_sum, th->th_urp, 0, 0);
1339                 th->th_urp = 0;
1340                 rewrite = 1;
1341         }
1342
1343         /* Process options */
1344         if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af))
1345                 rewrite = 1;
1346
1347         /* copy back packet headers if we sanitized */
1348         if (rewrite)
1349                 m_copyback(m, off, sizeof(*th), (caddr_t)th);
1350
1351         return (PF_PASS);
1352
1353  tcp_drop:
1354         REASON_SET(&reason, PFRES_NORM);
1355         if (rm != NULL && r->log)
1356                 PFLOG_PACKET(kif, h, m, AF_INET, dir, reason, r, NULL, NULL, pd);
1357         return (PF_DROP);
1358 }
1359
1360 int
1361 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd,
1362     struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst)
1363 {
1364         u_int32_t tsval, tsecr;
1365         u_int8_t hdr[60];
1366         u_int8_t *opt;
1367
1368         KASSERT((src->scrub == NULL),
1369             ("pf_normalize_tcp_init: src->scrub != NULL"));
1370
1371         src->scrub = kmalloc(sizeof(struct pf_state_scrub), M_PFSTATESCRUBPL,
1372             M_NOWAIT | M_ZERO);
1373         if (src->scrub == NULL)
1374                 return (1);
1375
1376         switch (pd->af) {
1377 #ifdef INET
1378         case AF_INET: {
1379                 struct ip *h = mtod(m, struct ip *);
1380                 src->scrub->pfss_ttl = h->ip_ttl;
1381                 break;
1382         }
1383 #endif /* INET */
1384 #ifdef INET6
1385         case AF_INET6: {
1386                 struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1387                 src->scrub->pfss_ttl = h->ip6_hlim;
1388                 break;
1389         }
1390 #endif /* INET6 */
1391         }
1392
1393
1394         /*
1395          * All normalizations below are only begun if we see the start of
1396          * the connections.  They must all set an enabled bit in pfss_flags
1397          */
1398         if ((th->th_flags & TH_SYN) == 0)
1399                 return (0);
1400
1401
1402         if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub &&
1403             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1404                 /* Diddle with TCP options */
1405                 int hlen;
1406                 opt = hdr + sizeof(struct tcphdr);
1407                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1408                 while (hlen >= TCPOLEN_TIMESTAMP) {
1409                         switch (*opt) {
1410                         case TCPOPT_EOL:        /* FALLTHROUGH */
1411                         case TCPOPT_NOP:
1412                                 opt++;
1413                                 hlen--;
1414                                 break;
1415                         case TCPOPT_TIMESTAMP:
1416                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1417                                         src->scrub->pfss_flags |=
1418                                             PFSS_TIMESTAMP;
1419                                         src->scrub->pfss_ts_mod = karc4random();
1420
1421                                         /* note PFSS_PAWS not set yet */
1422                                         memcpy(&tsval, &opt[2],
1423                                             sizeof(u_int32_t));
1424                                         memcpy(&tsecr, &opt[6],
1425                                             sizeof(u_int32_t));
1426                                         src->scrub->pfss_tsval0 = ntohl(tsval);
1427                                         src->scrub->pfss_tsval = ntohl(tsval);
1428                                         src->scrub->pfss_tsecr = ntohl(tsecr);
1429                                         getmicrouptime(&src->scrub->pfss_last);
1430                                 }
1431                                 /* FALLTHROUGH */
1432                         default:
1433                                 hlen -= MAX(opt[1], 2);
1434                                 opt += MAX(opt[1], 2);
1435                                 break;
1436                         }
1437                 }
1438         }
1439
1440         return (0);
1441 }
1442
1443 void
1444 pf_normalize_tcp_cleanup(struct pf_state *state)
1445 {
1446         if (state->src.scrub)
1447                 kfree(state->src.scrub, M_PFSTATESCRUBPL);
1448         if (state->dst.scrub)
1449                 kfree(state->dst.scrub, M_PFSTATESCRUBPL);
1450
1451         /* Someday... flush the TCP segment reassembly descriptors. */
1452 }
1453
1454 int
1455 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd,
1456     u_short *reason, struct tcphdr *th, struct pf_state *state,
1457     struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback)
1458 {
1459         struct timeval uptime;
1460         u_int32_t tsval, tsecr;
1461         u_int tsval_from_last;
1462         u_int8_t hdr[60];
1463         u_int8_t *opt;
1464         int copyback = 0;
1465         int got_ts = 0;
1466
1467         KASSERT((src->scrub || dst->scrub),
1468             ("pf_normalize_tcp_statefull: src->scrub && dst->scrub!"));
1469
1470         /*
1471          * Enforce the minimum TTL seen for this connection.  Negate a common
1472          * technique to evade an intrusion detection system and confuse
1473          * firewall state code.
1474          */
1475         switch (pd->af) {
1476 #ifdef INET
1477         case AF_INET: {
1478                 if (src->scrub) {
1479                         struct ip *h = mtod(m, struct ip *);
1480                         if (h->ip_ttl > src->scrub->pfss_ttl)
1481                                 src->scrub->pfss_ttl = h->ip_ttl;
1482                         h->ip_ttl = src->scrub->pfss_ttl;
1483                 }
1484                 break;
1485         }
1486 #endif /* INET */
1487 #ifdef INET6
1488         case AF_INET6: {
1489                 if (src->scrub) {
1490                         struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1491                         if (h->ip6_hlim > src->scrub->pfss_ttl)
1492                                 src->scrub->pfss_ttl = h->ip6_hlim;
1493                         h->ip6_hlim = src->scrub->pfss_ttl;
1494                 }
1495                 break;
1496         }
1497 #endif /* INET6 */
1498         }
1499
1500         if (th->th_off > (sizeof(struct tcphdr) >> 2) &&
1501             ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) ||
1502             (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) &&
1503             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1504                 /* Diddle with TCP options */
1505                 int hlen;
1506                 opt = hdr + sizeof(struct tcphdr);
1507                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1508                 while (hlen >= TCPOLEN_TIMESTAMP) {
1509                         switch (*opt) {
1510                         case TCPOPT_EOL:        /* FALLTHROUGH */
1511                         case TCPOPT_NOP:
1512                                 opt++;
1513                                 hlen--;
1514                                 break;
1515                         case TCPOPT_TIMESTAMP:
1516                                 /* Modulate the timestamps.  Can be used for
1517                                  * NAT detection, OS uptime determination or
1518                                  * reboot detection.
1519                                  */
1520
1521                                 if (got_ts) {
1522                                         /* Huh?  Multiple timestamps!? */
1523                                         if (pf_status.debug >= PF_DEBUG_MISC) {
1524                                                 DPFPRINTF(("multiple TS??"));
1525                                                 pf_print_state(state);
1526                                                 kprintf("\n");
1527                                         }
1528                                         REASON_SET(reason, PFRES_TS);
1529                                         return (PF_DROP);
1530                                 }
1531                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1532                                         memcpy(&tsval, &opt[2],
1533                                             sizeof(u_int32_t));
1534                                         if (tsval && src->scrub &&
1535                                             (src->scrub->pfss_flags &
1536                                             PFSS_TIMESTAMP)) {
1537                                                 tsval = ntohl(tsval);
1538                                                 pf_change_a(&opt[2],
1539                                                     &th->th_sum,
1540                                                     htonl(tsval +
1541                                                     src->scrub->pfss_ts_mod),
1542                                                     0);
1543                                                 copyback = 1;
1544                                         }
1545
1546                                         /* Modulate TS reply iff valid (!0) */
1547                                         memcpy(&tsecr, &opt[6],
1548                                             sizeof(u_int32_t));
1549                                         if (tsecr && dst->scrub &&
1550                                             (dst->scrub->pfss_flags &
1551                                             PFSS_TIMESTAMP)) {
1552                                                 tsecr = ntohl(tsecr)
1553                                                     - dst->scrub->pfss_ts_mod;
1554                                                 pf_change_a(&opt[6],
1555                                                     &th->th_sum, htonl(tsecr),
1556                                                     0);
1557                                                 copyback = 1;
1558                                         }
1559                                         got_ts = 1;
1560                                 }
1561                                 /* FALLTHROUGH */
1562                         default:
1563                                 hlen -= MAX(opt[1], 2);
1564                                 opt += MAX(opt[1], 2);
1565                                 break;
1566                         }
1567                 }
1568                 if (copyback) {
1569                         /* Copyback the options, caller copys back header */
1570                         *writeback = 1;
1571                         m_copyback(m, off + sizeof(struct tcphdr),
1572                             (th->th_off << 2) - sizeof(struct tcphdr), hdr +
1573                             sizeof(struct tcphdr));
1574                 }
1575         }
1576
1577
1578         /*
1579          * Must invalidate PAWS checks on connections idle for too long.
1580          * The fastest allowed timestamp clock is 1ms.  That turns out to
1581          * be about 24 days before it wraps.  XXX Right now our lowerbound
1582          * TS echo check only works for the first 12 days of a connection
1583          * when the TS has exhausted half its 32bit space
1584          */
1585 #define TS_MAX_IDLE     (24*24*60*60)
1586 #define TS_MAX_CONN     (12*24*60*60)   /* XXX remove when better tsecr check */
1587
1588         getmicrouptime(&uptime);
1589         if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) &&
1590             (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE ||
1591             time_second - state->creation > TS_MAX_CONN))  {
1592                 if (pf_status.debug >= PF_DEBUG_MISC) {
1593                         DPFPRINTF(("src idled out of PAWS\n"));
1594                         pf_print_state(state);
1595                         kprintf("\n");
1596                 }
1597                 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS)
1598                     | PFSS_PAWS_IDLED;
1599         }
1600         if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) &&
1601             uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) {
1602                 if (pf_status.debug >= PF_DEBUG_MISC) {
1603                         DPFPRINTF(("dst idled out of PAWS\n"));
1604                         pf_print_state(state);
1605                         kprintf("\n");
1606                 }
1607                 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS)
1608                     | PFSS_PAWS_IDLED;
1609         }
1610
1611         if (got_ts && src->scrub && dst->scrub &&
1612             (src->scrub->pfss_flags & PFSS_PAWS) &&
1613             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1614                 /* Validate that the timestamps are "in-window".
1615                  * RFC1323 describes TCP Timestamp options that allow
1616                  * measurement of RTT (round trip time) and PAWS
1617                  * (protection against wrapped sequence numbers).  PAWS
1618                  * gives us a set of rules for rejecting packets on
1619                  * long fat pipes (packets that were somehow delayed
1620                  * in transit longer than the time it took to send the
1621                  * full TCP sequence space of 4Gb).  We can use these
1622                  * rules and infer a few others that will let us treat
1623                  * the 32bit timestamp and the 32bit echoed timestamp
1624                  * as sequence numbers to prevent a blind attacker from
1625                  * inserting packets into a connection.
1626                  *
1627                  * RFC1323 tells us:
1628                  *  - The timestamp on this packet must be greater than
1629                  *    or equal to the last value echoed by the other
1630                  *    endpoint.  The RFC says those will be discarded
1631                  *    since it is a dup that has already been acked.
1632                  *    This gives us a lowerbound on the timestamp.
1633                  *        timestamp >= other last echoed timestamp
1634                  *  - The timestamp will be less than or equal to
1635                  *    the last timestamp plus the time between the
1636                  *    last packet and now.  The RFC defines the max
1637                  *    clock rate as 1ms.  We will allow clocks to be
1638                  *    up to 10% fast and will allow a total difference
1639                  *    or 30 seconds due to a route change.  And this
1640                  *    gives us an upperbound on the timestamp.
1641                  *        timestamp <= last timestamp + max ticks
1642                  *    We have to be careful here.  Windows will send an
1643                  *    initial timestamp of zero and then initialize it
1644                  *    to a random value after the 3whs; presumably to
1645                  *    avoid a DoS by having to call an expensive RNG
1646                  *    during a SYN flood.  Proof MS has at least one
1647                  *    good security geek.
1648                  *
1649                  *  - The TCP timestamp option must also echo the other
1650                  *    endpoints timestamp.  The timestamp echoed is the
1651                  *    one carried on the earliest unacknowledged segment
1652                  *    on the left edge of the sequence window.  The RFC
1653                  *    states that the host will reject any echoed
1654                  *    timestamps that were larger than any ever sent.
1655                  *    This gives us an upperbound on the TS echo.
1656                  *        tescr <= largest_tsval
1657                  *  - The lowerbound on the TS echo is a little more
1658                  *    tricky to determine.  The other endpoint's echoed
1659                  *    values will not decrease.  But there may be
1660                  *    network conditions that re-order packets and
1661                  *    cause our view of them to decrease.  For now the
1662                  *    only lowerbound we can safely determine is that
1663                  *    the TS echo will never be less than the original
1664                  *    TS.  XXX There is probably a better lowerbound.
1665                  *    Remove TS_MAX_CONN with better lowerbound check.
1666                  *        tescr >= other original TS
1667                  *
1668                  * It is also important to note that the fastest
1669                  * timestamp clock of 1ms will wrap its 32bit space in
1670                  * 24 days.  So we just disable TS checking after 24
1671                  * days of idle time.  We actually must use a 12d
1672                  * connection limit until we can come up with a better
1673                  * lowerbound to the TS echo check.
1674                  */
1675                 struct timeval delta_ts;
1676                 int ts_fudge;
1677
1678
1679                 /*
1680                  * PFTM_TS_DIFF is how many seconds of leeway to allow
1681                  * a host's timestamp.  This can happen if the previous
1682                  * packet got delayed in transit for much longer than
1683                  * this packet.
1684                  */
1685                 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0)
1686                         ts_fudge = pf_default_rule.timeout[PFTM_TS_DIFF];
1687
1688
1689                 /* Calculate max ticks since the last timestamp */
1690 #define TS_MAXFREQ      1100            /* RFC max TS freq of 1Khz + 10% skew */
1691 #define TS_MICROSECS    1000000         /* microseconds per second */
1692 #ifndef timersub
1693 #define timersub(tvp, uvp, vvp)                                         \
1694         do {                                                            \
1695                 (vvp)->tv_sec = (tvp)->tv_sec - (uvp)->tv_sec;          \
1696                 (vvp)->tv_usec = (tvp)->tv_usec - (uvp)->tv_usec;       \
1697                 if ((vvp)->tv_usec < 0) {                               \
1698                         (vvp)->tv_sec--;                                \
1699                         (vvp)->tv_usec += 1000000;                      \
1700                 }                                                       \
1701         } while (0)
1702 #endif
1703
1704                 timersub(&uptime, &src->scrub->pfss_last, &delta_ts);
1705                 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ;
1706                 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ);
1707
1708
1709                 if ((src->state >= TCPS_ESTABLISHED &&
1710                     dst->state >= TCPS_ESTABLISHED) &&
1711                     (SEQ_LT(tsval, dst->scrub->pfss_tsecr) ||
1712                     SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) ||
1713                     (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) ||
1714                     SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) {
1715                         /* Bad RFC1323 implementation or an insertion attack.
1716                          *
1717                          * - Solaris 2.6 and 2.7 are known to send another ACK
1718                          *   after the FIN,FIN|ACK,ACK closing that carries
1719                          *   an old timestamp.
1720                          */
1721
1722                         DPFPRINTF(("Timestamp failed %c%c%c%c\n",
1723                             SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ',
1724                             SEQ_GT(tsval, src->scrub->pfss_tsval +
1725                             tsval_from_last) ? '1' : ' ',
1726                             SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ',
1727                             SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' '));
1728                         DPFPRINTF((" tsval: %u  tsecr: %u  +ticks: %u  "
1729                             "idle: %lus %lums\n",
1730                             tsval, tsecr, tsval_from_last, delta_ts.tv_sec,
1731                             delta_ts.tv_usec / 1000));
1732                         DPFPRINTF((" src->tsval: %u  tsecr: %u\n",
1733                             src->scrub->pfss_tsval, src->scrub->pfss_tsecr));
1734                         DPFPRINTF((" dst->tsval: %u  tsecr: %u  tsval0: %u"
1735                             "\n", dst->scrub->pfss_tsval,
1736                             dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0));
1737                         if (pf_status.debug >= PF_DEBUG_MISC) {
1738                                 pf_print_state(state);
1739                                 pf_print_flags(th->th_flags);
1740                                 kprintf("\n");
1741                         }
1742                         REASON_SET(reason, PFRES_TS);
1743                         return (PF_DROP);
1744                 }
1745
1746                 /* XXX I'd really like to require tsecr but it's optional */
1747
1748         } else if (!got_ts && (th->th_flags & TH_RST) == 0 &&
1749             ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED)
1750             || pd->p_len > 0 || (th->th_flags & TH_SYN)) &&
1751             src->scrub && dst->scrub &&
1752             (src->scrub->pfss_flags & PFSS_PAWS) &&
1753             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1754                 /* Didn't send a timestamp.  Timestamps aren't really useful
1755                  * when:
1756                  *  - connection opening or closing (often not even sent).
1757                  *    but we must not let an attacker to put a FIN on a
1758                  *    data packet to sneak it through our ESTABLISHED check.
1759                  *  - on a TCP reset.  RFC suggests not even looking at TS.
1760                  *  - on an empty ACK.  The TS will not be echoed so it will
1761                  *    probably not help keep the RTT calculation in sync and
1762                  *    there isn't as much danger when the sequence numbers
1763                  *    got wrapped.  So some stacks don't include TS on empty
1764                  *    ACKs :-(
1765                  *
1766                  * To minimize the disruption to mostly RFC1323 conformant
1767                  * stacks, we will only require timestamps on data packets.
1768                  *
1769                  * And what do ya know, we cannot require timestamps on data
1770                  * packets.  There appear to be devices that do legitimate
1771                  * TCP connection hijacking.  There are HTTP devices that allow
1772                  * a 3whs (with timestamps) and then buffer the HTTP request.
1773                  * If the intermediate device has the HTTP response cache, it
1774                  * will spoof the response but not bother timestamping its
1775                  * packets.  So we can look for the presence of a timestamp in
1776                  * the first data packet and if there, require it in all future
1777                  * packets.
1778                  */
1779
1780                 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) {
1781                         /*
1782                          * Hey!  Someone tried to sneak a packet in.  Or the
1783                          * stack changed its RFC1323 behavior?!?!
1784                          */
1785                         if (pf_status.debug >= PF_DEBUG_MISC) {
1786                                 DPFPRINTF(("Did not receive expected RFC1323 "
1787                                     "timestamp\n"));
1788                                 pf_print_state(state);
1789                                 pf_print_flags(th->th_flags);
1790                                 kprintf("\n");
1791                         }
1792                         REASON_SET(reason, PFRES_TS);
1793                         return (PF_DROP);
1794                 }
1795         }
1796
1797
1798         /*
1799          * We will note if a host sends his data packets with or without
1800          * timestamps.  And require all data packets to contain a timestamp
1801          * if the first does.  PAWS implicitly requires that all data packets be
1802          * timestamped.  But I think there are middle-man devices that hijack
1803          * TCP streams immediately after the 3whs and don't timestamp their
1804          * packets (seen in a WWW accelerator or cache).
1805          */
1806         if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags &
1807             (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) {
1808                 if (got_ts)
1809                         src->scrub->pfss_flags |= PFSS_DATA_TS;
1810                 else {
1811                         src->scrub->pfss_flags |= PFSS_DATA_NOTS;
1812                         if (pf_status.debug >= PF_DEBUG_MISC && dst->scrub &&
1813                             (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) {
1814                                 /* Don't warn if other host rejected RFC1323 */
1815                                 DPFPRINTF(("Broken RFC1323 stack did not "
1816                                     "timestamp data packet. Disabled PAWS "
1817                                     "security.\n"));
1818                                 pf_print_state(state);
1819                                 pf_print_flags(th->th_flags);
1820                                 kprintf("\n");
1821                         }
1822                 }
1823         }
1824
1825
1826         /*
1827          * Update PAWS values
1828          */
1829         if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags &
1830             (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) {
1831                 getmicrouptime(&src->scrub->pfss_last);
1832                 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) ||
1833                     (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1834                         src->scrub->pfss_tsval = tsval;
1835
1836                 if (tsecr) {
1837                         if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) ||
1838                             (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1839                                 src->scrub->pfss_tsecr = tsecr;
1840
1841                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 &&
1842                             (SEQ_LT(tsval, src->scrub->pfss_tsval0) ||
1843                             src->scrub->pfss_tsval0 == 0)) {
1844                                 /* tsval0 MUST be the lowest timestamp */
1845                                 src->scrub->pfss_tsval0 = tsval;
1846                         }
1847
1848                         /* Only fully initialized after a TS gets echoed */
1849                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0)
1850                                 src->scrub->pfss_flags |= PFSS_PAWS;
1851                 }
1852         }
1853
1854         /* I have a dream....  TCP segment reassembly.... */
1855         return (0);
1856 }
1857
1858 int
1859 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th,
1860     int off, sa_family_t af)
1861 {
1862         u_int16_t       *mss;
1863         int              thoff;
1864         int              opt, cnt, optlen = 0;
1865         int              rewrite = 0;
1866         u_char           opts[TCP_MAXOLEN];
1867         u_char          *optp = opts;
1868
1869         thoff = th->th_off << 2;
1870         cnt = thoff - sizeof(struct tcphdr);
1871
1872         if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt,
1873             NULL, NULL, af))
1874                 return (rewrite);
1875
1876         for (; cnt > 0; cnt -= optlen, optp += optlen) {
1877                 opt = optp[0];
1878                 if (opt == TCPOPT_EOL)
1879                         break;
1880                 if (opt == TCPOPT_NOP)
1881                         optlen = 1;
1882                 else {
1883                         if (cnt < 2)
1884                                 break;
1885                         optlen = optp[1];
1886                         if (optlen < 2 || optlen > cnt)
1887                                 break;
1888                 }
1889                 switch (opt) {
1890                 case TCPOPT_MAXSEG:
1891                         mss = (u_int16_t *)(optp + 2);
1892                         if ((ntohs(*mss)) > r->max_mss) {
1893                                 th->th_sum = pf_cksum_fixup(th->th_sum,
1894                                     *mss, htons(r->max_mss), 0);
1895                                 *mss = htons(r->max_mss);
1896                                 rewrite = 1;
1897                         }
1898                         break;
1899                 default:
1900                         break;
1901                 }
1902         }
1903
1904         if (rewrite)
1905                 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts);
1906
1907         return (rewrite);
1908 }