sys/netpfil/pf/pf_norm.c

   1 /*-
   2  * Copyright 2001 Niels Provos <provos@citi.umich.edu>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  *
  25  *      $OpenBSD: pf_norm.c,v 1.114 2009/01/29 14:11:45 henning Exp $
  26  */
  27
  28 #include <sys/cdefs.h>
  29 __FBSDID("$FreeBSD$");
  30
  31 #include "opt_inet.h"
  32 #include "opt_inet6.h"
  33 #include "opt_pf.h"
  34
  35 #include <sys/param.h>
  36 #include <sys/lock.h>
  37 #include <sys/mbuf.h>
  38 #include <sys/mutex.h>
  39 #include <sys/refcount.h>
  40 #include <sys/rwlock.h>
  41 #include <sys/socket.h>
  42
  43 #include <net/if.h>
  44 #include <net/vnet.h>
  45 #include <net/pfvar.h>
  46 #include <net/if_pflog.h>
  47
  48 #include <netinet/in.h>
  49 #include <netinet/ip.h>
  50 #include <netinet/ip_var.h>
  51 #include <netinet/tcp.h>
  52 #include <netinet/tcp_fsm.h>
  53 #include <netinet/tcp_seq.h>
  54
  55 #ifdef INET6
  56 #include <netinet/ip6.h>
  57 #endif /* INET6 */
  58
  59 struct pf_frent {
  60         LIST_ENTRY(pf_frent) fr_next;
  61         union {
  62                 struct {
  63                         struct ip *_fr_ip;
  64                         struct mbuf *_fr_m;
  65                 } _frag;
  66                 struct {
  67                         uint16_t _fr_off;
  68                         uint16_t _fr_end;
  69                 } _cache;
  70         } _u;
  71 };
  72 #define fr_ip   _u._frag._fr_ip
  73 #define fr_m    _u._frag._fr_m
  74 #define fr_off  _u._cache._fr_off
  75 #define fr_end  _u._cache._fr_end
  76
  77 struct pf_fragment {
  78         RB_ENTRY(pf_fragment) fr_entry;
  79         TAILQ_ENTRY(pf_fragment) frag_next;
  80         struct in_addr  fr_src;
  81         struct in_addr  fr_dst;
  82         u_int8_t        fr_p;           /* protocol of this fragment */
  83         u_int8_t        fr_flags;       /* status flags */
  84 #define PFFRAG_SEENLAST 0x0001          /* Seen the last fragment for this */
  85 #define PFFRAG_NOBUFFER 0x0002          /* Non-buffering fragment cache */
  86 #define PFFRAG_DROP     0x0004          /* Drop all fragments */
  87 #define BUFFER_FRAGMENTS(fr)    (!((fr)->fr_flags & PFFRAG_NOBUFFER))
  88         u_int16_t       fr_id;          /* fragment id for reassemble */
  89         u_int16_t       fr_max;         /* fragment data max */
  90         u_int32_t       fr_timeout;
  91         LIST_HEAD(, pf_frent) fr_queue;
  92 };
  93
  94 static struct mtx pf_frag_mtx;
  95 #define PF_FRAG_LOCK()          mtx_lock(&pf_frag_mtx)
  96 #define PF_FRAG_UNLOCK()        mtx_unlock(&pf_frag_mtx)
  97 #define PF_FRAG_ASSERT()        mtx_assert(&pf_frag_mtx, MA_OWNED)
  98
  99 VNET_DEFINE(uma_zone_t, pf_state_scrub_z);      /* XXX: shared with pfsync */
 100
 101 static VNET_DEFINE(uma_zone_t, pf_frent_z);
 102 #define V_pf_frent_z    VNET(pf_frent_z)
 103 static VNET_DEFINE(uma_zone_t, pf_frag_z);
 104 #define V_pf_frag_z     VNET(pf_frag_z)
 105
 106 TAILQ_HEAD(pf_fragqueue, pf_fragment);
 107 TAILQ_HEAD(pf_cachequeue, pf_fragment);
 108 static VNET_DEFINE(struct pf_fragqueue, pf_fragqueue);
 109 #define V_pf_fragqueue                  VNET(pf_fragqueue)
 110 static VNET_DEFINE(struct pf_cachequeue,        pf_cachequeue);
 111 #define V_pf_cachequeue                 VNET(pf_cachequeue)
 112 RB_HEAD(pf_frag_tree, pf_fragment);
 113 static VNET_DEFINE(struct pf_frag_tree, pf_frag_tree);
 114 #define V_pf_frag_tree                  VNET(pf_frag_tree)
 115 static VNET_DEFINE(struct pf_frag_tree, pf_cache_tree);
 116 #define V_pf_cache_tree                 VNET(pf_cache_tree)
 117 static int               pf_frag_compare(struct pf_fragment *,
 118                             struct pf_fragment *);
 119 static RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 120 static RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 121
 122 /* Private prototypes */
 123 static void              pf_free_fragment(struct pf_fragment *);
 124 static void              pf_remove_fragment(struct pf_fragment *);
 125 static int               pf_normalize_tcpopt(struct pf_rule *, struct mbuf *,
 126                             struct tcphdr *, int, sa_family_t);
 127 #ifdef INET
 128 static void              pf_ip2key(struct pf_fragment *, struct ip *);
 129 static void              pf_scrub_ip(struct mbuf **, u_int32_t, u_int8_t,
 130                             u_int8_t);
 131 static void              pf_flush_fragments(void);
 132 static struct pf_fragment *pf_find_fragment(struct ip *, struct pf_frag_tree *);
 133 static struct mbuf      *pf_reassemble(struct mbuf **, struct pf_fragment **,
 134                             struct pf_frent *, int);
 135 static struct mbuf      *pf_fragcache(struct mbuf **, struct ip*,
 136                             struct pf_fragment **, int, int, int *);
 137 #endif /* INET */
 138 #ifdef INET6
 139 static void              pf_scrub_ip6(struct mbuf **, u_int8_t);
 140 #endif
 141 #define DPFPRINTF(x) do {                               \
 142         if (V_pf_status.debug >= PF_DEBUG_MISC) {       \
 143                 printf("%s: ", __func__);               \
 144                 printf x ;                              \
 145         }                                               \
 146 } while(0)
 147
 148 void
 149 pf_normalize_init(void)
 150 {
 151
 152         V_pf_frag_z = uma_zcreate("pf frags", sizeof(struct pf_fragment),
 153             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 154         V_pf_frent_z = uma_zcreate("pf frag entries", sizeof(struct pf_frent),
 155             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 156         V_pf_state_scrub_z = uma_zcreate("pf state scrubs",
 157             sizeof(struct pf_state_scrub),  NULL, NULL, NULL, NULL,
 158             UMA_ALIGN_PTR, 0);
 159
 160         V_pf_limits[PF_LIMIT_FRAGS].zone = V_pf_frent_z;
 161         V_pf_limits[PF_LIMIT_FRAGS].limit = PFFRAG_FRENT_HIWAT;
 162         uma_zone_set_max(V_pf_frent_z, PFFRAG_FRENT_HIWAT);
 163         uma_zone_set_warning(V_pf_frent_z, "PF frag entries limit reached");
 164
 165         mtx_init(&pf_frag_mtx, "pf fragments", NULL, MTX_DEF);
 166
 167         TAILQ_INIT(&V_pf_fragqueue);
 168         TAILQ_INIT(&V_pf_cachequeue);
 169 }
 170
 171 void
 172 pf_normalize_cleanup(void)
 173 {
 174
 175         uma_zdestroy(V_pf_state_scrub_z);
 176         uma_zdestroy(V_pf_frent_z);
 177         uma_zdestroy(V_pf_frag_z);
 178
 179         mtx_destroy(&pf_frag_mtx);
 180 }
 181
 182 static int
 183 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b)
 184 {
 185         int     diff;
 186
 187         if ((diff = a->fr_id - b->fr_id))
 188                 return (diff);
 189         else if ((diff = a->fr_p - b->fr_p))
 190                 return (diff);
 191         else if (a->fr_src.s_addr < b->fr_src.s_addr)
 192                 return (-1);
 193         else if (a->fr_src.s_addr > b->fr_src.s_addr)
 194                 return (1);
 195         else if (a->fr_dst.s_addr < b->fr_dst.s_addr)
 196                 return (-1);
 197         else if (a->fr_dst.s_addr > b->fr_dst.s_addr)
 198                 return (1);
 199         return (0);
 200 }
 201
 202 void
 203 pf_purge_expired_fragments(void)
 204 {
 205         struct pf_fragment      *frag;
 206         u_int32_t                expire = time_uptime -
 207                                     V_pf_default_rule.timeout[PFTM_FRAG];
 208
 209         PF_FRAG_LOCK();
 210         while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) {
 211                 KASSERT((BUFFER_FRAGMENTS(frag)),
 212                     ("BUFFER_FRAGMENTS(frag) == 0: %s", __FUNCTION__));
 213                 if (frag->fr_timeout > expire)
 214                         break;
 215
 216                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 217                 pf_free_fragment(frag);
 218         }
 219
 220         while ((frag = TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue)) != NULL) {
 221                 KASSERT((!BUFFER_FRAGMENTS(frag)),
 222                     ("BUFFER_FRAGMENTS(frag) != 0: %s", __FUNCTION__));
 223                 if (frag->fr_timeout > expire)
 224                         break;
 225
 226                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 227                 pf_free_fragment(frag);
 228                 KASSERT((TAILQ_EMPTY(&V_pf_cachequeue) ||
 229                     TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue) != frag),
 230                     ("!(TAILQ_EMPTY() || TAILQ_LAST() == farg): %s",
 231                     __FUNCTION__));
 232         }
 233         PF_FRAG_UNLOCK();
 234 }
 235
 236 #ifdef INET
 237 /*
 238  * Try to flush old fragments to make space for new ones
 239  */
 240 static void
 241 pf_flush_fragments(void)
 242 {
 243         struct pf_fragment      *frag, *cache;
 244         int                      goal;
 245
 246         PF_FRAG_ASSERT();
 247
 248         goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10;
 249         DPFPRINTF(("trying to free %d frag entriess\n", goal));
 250         while (goal < uma_zone_get_cur(V_pf_frent_z)) {
 251                 frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue);
 252                 if (frag)
 253                         pf_free_fragment(frag);
 254                 cache = TAILQ_LAST(&V_pf_cachequeue, pf_cachequeue);
 255                 if (cache)
 256                         pf_free_fragment(cache);
 257                 if (frag == NULL && cache == NULL)
 258                         break;
 259         }
 260 }
 261 #endif /* INET */
 262
 263 /* Frees the fragments and all associated entries */
 264 static void
 265 pf_free_fragment(struct pf_fragment *frag)
 266 {
 267         struct pf_frent         *frent;
 268
 269         PF_FRAG_ASSERT();
 270
 271         /* Free all fragments */
 272         if (BUFFER_FRAGMENTS(frag)) {
 273                 for (frent = LIST_FIRST(&frag->fr_queue); frent;
 274                     frent = LIST_FIRST(&frag->fr_queue)) {
 275                         LIST_REMOVE(frent, fr_next);
 276
 277                         m_freem(frent->fr_m);
 278                         uma_zfree(V_pf_frent_z, frent);
 279                 }
 280         } else {
 281                 for (frent = LIST_FIRST(&frag->fr_queue); frent;
 282                     frent = LIST_FIRST(&frag->fr_queue)) {
 283                         LIST_REMOVE(frent, fr_next);
 284
 285                         KASSERT((LIST_EMPTY(&frag->fr_queue) ||
 286                             LIST_FIRST(&frag->fr_queue)->fr_off >
 287                             frent->fr_end),
 288                             ("! (LIST_EMPTY() || LIST_FIRST()->fr_off >"
 289                             " frent->fr_end): %s", __func__));
 290
 291                         uma_zfree(V_pf_frent_z, frent);
 292                 }
 293         }
 294
 295         pf_remove_fragment(frag);
 296 }
 297
 298 #ifdef INET
 299 static void
 300 pf_ip2key(struct pf_fragment *key, struct ip *ip)
 301 {
 302         key->fr_p = ip->ip_p;
 303         key->fr_id = ip->ip_id;
 304         key->fr_src.s_addr = ip->ip_src.s_addr;
 305         key->fr_dst.s_addr = ip->ip_dst.s_addr;
 306 }
 307
 308 static struct pf_fragment *
 309 pf_find_fragment(struct ip *ip, struct pf_frag_tree *tree)
 310 {
 311         struct pf_fragment       key;
 312         struct pf_fragment      *frag;
 313
 314         PF_FRAG_ASSERT();
 315
 316         pf_ip2key(&key, ip);
 317
 318         frag = RB_FIND(pf_frag_tree, tree, &key);
 319         if (frag != NULL) {
 320                 /* XXX Are we sure we want to update the timeout? */
 321                 frag->fr_timeout = time_uptime;
 322                 if (BUFFER_FRAGMENTS(frag)) {
 323                         TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 324                         TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
 325                 } else {
 326                         TAILQ_REMOVE(&V_pf_cachequeue, frag, frag_next);
 327                         TAILQ_INSERT_HEAD(&V_pf_cachequeue, frag, frag_next);
 328                 }
 329         }
 330
 331         return (frag);
 332 }
 333 #endif /* INET */
 334
 335 /* Removes a fragment from the fragment queue and frees the fragment */
 336
 337 static void
 338 pf_remove_fragment(struct pf_fragment *frag)
 339 {
 340
 341         PF_FRAG_ASSERT();
 342
 343         if (BUFFER_FRAGMENTS(frag)) {
 344                 RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag);
 345                 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 346                 uma_zfree(V_pf_frag_z, frag);
 347         } else {
 348                 RB_REMOVE(pf_frag_tree, &V_pf_cache_tree, frag);
 349                 TAILQ_REMOVE(&V_pf_cachequeue, frag, frag_next);
 350                 uma_zfree(V_pf_frag_z, frag);
 351         }
 352 }
 353
 354 #ifdef INET
 355 #define FR_IP_OFF(fr)   ((ntohs((fr)->fr_ip->ip_off) & IP_OFFMASK) << 3)
 356 static struct mbuf *
 357 pf_reassemble(struct mbuf **m0, struct pf_fragment **frag,
 358     struct pf_frent *frent, int mff)
 359 {
 360         struct mbuf     *m = *m0, *m2;
 361         struct pf_frent *frea, *next;
 362         struct pf_frent *frep = NULL;
 363         struct ip       *ip = frent->fr_ip;
 364         int              hlen = ip->ip_hl << 2;
 365         u_int16_t        off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3;
 366         u_int16_t        ip_len = ntohs(ip->ip_len) - ip->ip_hl * 4;
 367         u_int16_t        max = ip_len + off;
 368
 369         PF_FRAG_ASSERT();
 370         KASSERT((*frag == NULL || BUFFER_FRAGMENTS(*frag)),
 371             ("! (*frag == NULL || BUFFER_FRAGMENTS(*frag)): %s", __FUNCTION__));
 372
 373         /* Strip off ip header */
 374         m->m_data += hlen;
 375         m->m_len -= hlen;
 376
 377         /* Create a new reassembly queue for this packet */
 378         if (*frag == NULL) {
 379                 *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 380                 if (*frag == NULL) {
 381                         pf_flush_fragments();
 382                         *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 383                         if (*frag == NULL)
 384                                 goto drop_fragment;
 385                 }
 386
 387                 (*frag)->fr_flags = 0;
 388                 (*frag)->fr_max = 0;
 389                 (*frag)->fr_src = frent->fr_ip->ip_src;
 390                 (*frag)->fr_dst = frent->fr_ip->ip_dst;
 391                 (*frag)->fr_p = frent->fr_ip->ip_p;
 392                 (*frag)->fr_id = frent->fr_ip->ip_id;
 393                 (*frag)->fr_timeout = time_uptime;
 394                 LIST_INIT(&(*frag)->fr_queue);
 395
 396                 RB_INSERT(pf_frag_tree, &V_pf_frag_tree, *frag);
 397                 TAILQ_INSERT_HEAD(&V_pf_fragqueue, *frag, frag_next);
 398
 399                 /* We do not have a previous fragment */
 400                 frep = NULL;
 401                 goto insert;
 402         }
 403
 404         /*
 405          * Find a fragment after the current one:
 406          *  - off contains the real shifted offset.
 407          */
 408         LIST_FOREACH(frea, &(*frag)->fr_queue, fr_next) {
 409                 if (FR_IP_OFF(frea) > off)
 410                         break;
 411                 frep = frea;
 412         }
 413
 414         KASSERT((frep != NULL || frea != NULL),
 415             ("!(frep != NULL || frea != NULL): %s", __FUNCTION__));;
 416
 417         if (frep != NULL &&
 418             FR_IP_OFF(frep) + ntohs(frep->fr_ip->ip_len) - frep->fr_ip->ip_hl *
 419             4 > off)
 420         {
 421                 u_int16_t       precut;
 422
 423                 precut = FR_IP_OFF(frep) + ntohs(frep->fr_ip->ip_len) -
 424                     frep->fr_ip->ip_hl * 4 - off;
 425                 if (precut >= ip_len)
 426                         goto drop_fragment;
 427                 m_adj(frent->fr_m, precut);
 428                 DPFPRINTF(("overlap -%d\n", precut));
 429                 /* Enforce 8 byte boundaries */
 430                 ip->ip_off = htons(ntohs(ip->ip_off) + (precut >> 3));
 431                 off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3;
 432                 ip_len -= precut;
 433                 ip->ip_len = htons(ip_len);
 434         }
 435
 436         for (; frea != NULL && ip_len + off > FR_IP_OFF(frea);
 437             frea = next)
 438         {
 439                 u_int16_t       aftercut;
 440
 441                 aftercut = ip_len + off - FR_IP_OFF(frea);
 442                 DPFPRINTF(("adjust overlap %d\n", aftercut));
 443                 if (aftercut < ntohs(frea->fr_ip->ip_len) - frea->fr_ip->ip_hl
 444                     * 4)
 445                 {
 446                         frea->fr_ip->ip_len =
 447                             htons(ntohs(frea->fr_ip->ip_len) - aftercut);
 448                         frea->fr_ip->ip_off = htons(ntohs(frea->fr_ip->ip_off) +
 449                             (aftercut >> 3));
 450                         m_adj(frea->fr_m, aftercut);
 451                         break;
 452                 }
 453
 454                 /* This fragment is completely overlapped, lose it */
 455                 next = LIST_NEXT(frea, fr_next);
 456                 m_freem(frea->fr_m);
 457                 LIST_REMOVE(frea, fr_next);
 458                 uma_zfree(V_pf_frent_z, frea);
 459         }
 460
 461  insert:
 462         /* Update maximum data size */
 463         if ((*frag)->fr_max < max)
 464                 (*frag)->fr_max = max;
 465         /* This is the last segment */
 466         if (!mff)
 467                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
 468
 469         if (frep == NULL)
 470                 LIST_INSERT_HEAD(&(*frag)->fr_queue, frent, fr_next);
 471         else
 472                 LIST_INSERT_AFTER(frep, frent, fr_next);
 473
 474         /* Check if we are completely reassembled */
 475         if (!((*frag)->fr_flags & PFFRAG_SEENLAST))
 476                 return (NULL);
 477
 478         /* Check if we have all the data */
 479         off = 0;
 480         for (frep = LIST_FIRST(&(*frag)->fr_queue); frep; frep = next) {
 481                 next = LIST_NEXT(frep, fr_next);
 482
 483                 off += ntohs(frep->fr_ip->ip_len) - frep->fr_ip->ip_hl * 4;
 484                 if (off < (*frag)->fr_max &&
 485                     (next == NULL || FR_IP_OFF(next) != off))
 486                 {
 487                         DPFPRINTF(("missing fragment at %d, next %d, max %d\n",
 488                             off, next == NULL ? -1 : FR_IP_OFF(next),
 489                             (*frag)->fr_max));
 490                         return (NULL);
 491                 }
 492         }
 493         DPFPRINTF(("%d < %d?\n", off, (*frag)->fr_max));
 494         if (off < (*frag)->fr_max)
 495                 return (NULL);
 496
 497         /* We have all the data */
 498         frent = LIST_FIRST(&(*frag)->fr_queue);
 499         KASSERT((frent != NULL), ("frent == NULL: %s", __FUNCTION__));
 500         if ((frent->fr_ip->ip_hl << 2) + off > IP_MAXPACKET) {
 501                 DPFPRINTF(("drop: too big: %d\n", off));
 502                 pf_free_fragment(*frag);
 503                 *frag = NULL;
 504                 return (NULL);
 505         }
 506         next = LIST_NEXT(frent, fr_next);
 507
 508         /* Magic from ip_input */
 509         ip = frent->fr_ip;
 510         m = frent->fr_m;
 511         m2 = m->m_next;
 512         m->m_next = NULL;
 513         m_cat(m, m2);
 514         uma_zfree(V_pf_frent_z, frent);
 515         for (frent = next; frent != NULL; frent = next) {
 516                 next = LIST_NEXT(frent, fr_next);
 517
 518                 m2 = frent->fr_m;
 519                 uma_zfree(V_pf_frent_z, frent);
 520                 m->m_pkthdr.csum_flags &= m2->m_pkthdr.csum_flags;
 521                 m->m_pkthdr.csum_data += m2->m_pkthdr.csum_data;
 522                 m_cat(m, m2);
 523         }
 524
 525         while (m->m_pkthdr.csum_data & 0xffff0000)
 526                 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) +
 527                     (m->m_pkthdr.csum_data >> 16);
 528         ip->ip_src = (*frag)->fr_src;
 529         ip->ip_dst = (*frag)->fr_dst;
 530
 531         /* Remove from fragment queue */
 532         pf_remove_fragment(*frag);
 533         *frag = NULL;
 534
 535         hlen = ip->ip_hl << 2;
 536         ip->ip_len = htons(off + hlen);
 537         m->m_len += hlen;
 538         m->m_data -= hlen;
 539
 540         /* some debugging cruft by sklower, below, will go away soon */
 541         /* XXX this should be done elsewhere */
 542         if (m->m_flags & M_PKTHDR) {
 543                 int plen = 0;
 544                 for (m2 = m; m2; m2 = m2->m_next)
 545                         plen += m2->m_len;
 546                 m->m_pkthdr.len = plen;
 547         }
 548
 549         DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len)));
 550         return (m);
 551
 552  drop_fragment:
 553         /* Oops - fail safe - drop packet */
 554         uma_zfree(V_pf_frent_z, frent);
 555         m_freem(m);
 556         return (NULL);
 557 }
 558
 559 static struct mbuf *
 560 pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff,
 561     int drop, int *nomem)
 562 {
 563         struct mbuf             *m = *m0;
 564         struct pf_frent         *frp, *fra, *cur = NULL;
 565         int                      ip_len = ntohs(h->ip_len) - (h->ip_hl << 2);
 566         u_int16_t                off = ntohs(h->ip_off) << 3;
 567         u_int16_t                max = ip_len + off;
 568         int                      hosed = 0;
 569
 570         PF_FRAG_ASSERT();
 571         KASSERT((*frag == NULL || !BUFFER_FRAGMENTS(*frag)),
 572             ("!(*frag == NULL || !BUFFER_FRAGMENTS(*frag)): %s", __FUNCTION__));
 573
 574         /* Create a new range queue for this packet */
 575         if (*frag == NULL) {
 576                 *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 577                 if (*frag == NULL) {
 578                         pf_flush_fragments();
 579                         *frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 580                         if (*frag == NULL)
 581                                 goto no_mem;
 582                 }
 583
 584                 /* Get an entry for the queue */
 585                 cur = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 586                 if (cur == NULL) {
 587                         uma_zfree(V_pf_frag_z, *frag);
 588                         *frag = NULL;
 589                         goto no_mem;
 590                 }
 591
 592                 (*frag)->fr_flags = PFFRAG_NOBUFFER;
 593                 (*frag)->fr_max = 0;
 594                 (*frag)->fr_src = h->ip_src;
 595                 (*frag)->fr_dst = h->ip_dst;
 596                 (*frag)->fr_p = h->ip_p;
 597                 (*frag)->fr_id = h->ip_id;
 598                 (*frag)->fr_timeout = time_uptime;
 599
 600                 cur->fr_off = off;
 601                 cur->fr_end = max;
 602                 LIST_INIT(&(*frag)->fr_queue);
 603                 LIST_INSERT_HEAD(&(*frag)->fr_queue, cur, fr_next);
 604
 605                 RB_INSERT(pf_frag_tree, &V_pf_cache_tree, *frag);
 606                 TAILQ_INSERT_HEAD(&V_pf_cachequeue, *frag, frag_next);
 607
 608                 DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max));
 609
 610                 goto pass;
 611         }
 612
 613         /*
 614          * Find a fragment after the current one:
 615          *  - off contains the real shifted offset.
 616          */
 617         frp = NULL;
 618         LIST_FOREACH(fra, &(*frag)->fr_queue, fr_next) {
 619                 if (fra->fr_off > off)
 620                         break;
 621                 frp = fra;
 622         }
 623
 624         KASSERT((frp != NULL || fra != NULL),
 625             ("!(frp != NULL || fra != NULL): %s", __FUNCTION__));
 626
 627         if (frp != NULL) {
 628                 int     precut;
 629
 630                 precut = frp->fr_end - off;
 631                 if (precut >= ip_len) {
 632                         /* Fragment is entirely a duplicate */
 633                         DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n",
 634                             h->ip_id, frp->fr_off, frp->fr_end, off, max));
 635                         goto drop_fragment;
 636                 }
 637                 if (precut == 0) {
 638                         /* They are adjacent.  Fixup cache entry */
 639                         DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n",
 640                             h->ip_id, frp->fr_off, frp->fr_end, off, max));
 641                         frp->fr_end = max;
 642                 } else if (precut > 0) {
 643                         /* The first part of this payload overlaps with a
 644                          * fragment that has already been passed.
 645                          * Need to trim off the first part of the payload.
 646                          * But to do so easily, we need to create another
 647                          * mbuf to throw the original header into.
 648                          */
 649
 650                         DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n",
 651                             h->ip_id, precut, frp->fr_off, frp->fr_end, off,
 652                             max));
 653
 654                         off += precut;
 655                         max -= precut;
 656                         /* Update the previous frag to encompass this one */
 657                         frp->fr_end = max;
 658
 659                         if (!drop) {
 660                                 /* XXX Optimization opportunity
 661                                  * This is a very heavy way to trim the payload.
 662                                  * we could do it much faster by diddling mbuf
 663                                  * internals but that would be even less legible
 664                                  * than this mbuf magic.  For my next trick,
 665                                  * I'll pull a rabbit out of my laptop.
 666                                  */
 667                                 *m0 = m_dup(m, M_NOWAIT);
 668                                 if (*m0 == NULL)
 669                                         goto no_mem;
 670                                 /* From KAME Project : We have missed this! */
 671                                 m_adj(*m0, (h->ip_hl << 2) -
 672                                     (*m0)->m_pkthdr.len);
 673
 674                                 KASSERT(((*m0)->m_next == NULL),
 675                                     ("(*m0)->m_next != NULL: %s",
 676                                     __FUNCTION__));
 677                                 m_adj(m, precut + (h->ip_hl << 2));
 678                                 m_cat(*m0, m);
 679                                 m = *m0;
 680                                 if (m->m_flags & M_PKTHDR) {
 681                                         int plen = 0;
 682                                         struct mbuf *t;
 683                                         for (t = m; t; t = t->m_next)
 684                                                 plen += t->m_len;
 685                                         m->m_pkthdr.len = plen;
 686                                 }
 687
 688
 689                                 h = mtod(m, struct ip *);
 690
 691                                 KASSERT(((int)m->m_len ==
 692                                     ntohs(h->ip_len) - precut),
 693                                     ("m->m_len != ntohs(h->ip_len) - precut: %s",
 694                                     __FUNCTION__));
 695                                 h->ip_off = htons(ntohs(h->ip_off) +
 696                                     (precut >> 3));
 697                                 h->ip_len = htons(ntohs(h->ip_len) - precut);
 698                         } else {
 699                                 hosed++;
 700                         }
 701                 } else {
 702                         /* There is a gap between fragments */
 703
 704                         DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n",
 705                             h->ip_id, -precut, frp->fr_off, frp->fr_end, off,
 706                             max));
 707
 708                         cur = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 709                         if (cur == NULL)
 710                                 goto no_mem;
 711
 712                         cur->fr_off = off;
 713                         cur->fr_end = max;
 714                         LIST_INSERT_AFTER(frp, cur, fr_next);
 715                 }
 716         }
 717
 718         if (fra != NULL) {
 719                 int     aftercut;
 720                 int     merge = 0;
 721
 722                 aftercut = max - fra->fr_off;
 723                 if (aftercut == 0) {
 724                         /* Adjacent fragments */
 725                         DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n",
 726                             h->ip_id, off, max, fra->fr_off, fra->fr_end));
 727                         fra->fr_off = off;
 728                         merge = 1;
 729                 } else if (aftercut > 0) {
 730                         /* Need to chop off the tail of this fragment */
 731                         DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n",
 732                             h->ip_id, aftercut, off, max, fra->fr_off,
 733                             fra->fr_end));
 734                         fra->fr_off = off;
 735                         max -= aftercut;
 736
 737                         merge = 1;
 738
 739                         if (!drop) {
 740                                 m_adj(m, -aftercut);
 741                                 if (m->m_flags & M_PKTHDR) {
 742                                         int plen = 0;
 743                                         struct mbuf *t;
 744                                         for (t = m; t; t = t->m_next)
 745                                                 plen += t->m_len;
 746                                         m->m_pkthdr.len = plen;
 747                                 }
 748                                 h = mtod(m, struct ip *);
 749                                 KASSERT(((int)m->m_len == ntohs(h->ip_len) - aftercut),
 750                                     ("m->m_len != ntohs(h->ip_len) - aftercut: %s",
 751                                     __FUNCTION__));
 752                                 h->ip_len = htons(ntohs(h->ip_len) - aftercut);
 753                         } else {
 754                                 hosed++;
 755                         }
 756                 } else if (frp == NULL) {
 757                         /* There is a gap between fragments */
 758                         DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n",
 759                             h->ip_id, -aftercut, off, max, fra->fr_off,
 760                             fra->fr_end));
 761
 762                         cur = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 763                         if (cur == NULL)
 764                                 goto no_mem;
 765
 766                         cur->fr_off = off;
 767                         cur->fr_end = max;
 768                         LIST_INSERT_BEFORE(fra, cur, fr_next);
 769                 }
 770
 771
 772                 /* Need to glue together two separate fragment descriptors */
 773                 if (merge) {
 774                         if (cur && fra->fr_off <= cur->fr_end) {
 775                                 /* Need to merge in a previous 'cur' */
 776                                 DPFPRINTF(("fragcache[%d]: adjacent(merge "
 777                                     "%d-%d) %d-%d (%d-%d)\n",
 778                                     h->ip_id, cur->fr_off, cur->fr_end, off,
 779                                     max, fra->fr_off, fra->fr_end));
 780                                 fra->fr_off = cur->fr_off;
 781                                 LIST_REMOVE(cur, fr_next);
 782                                 uma_zfree(V_pf_frent_z, cur);
 783                                 cur = NULL;
 784
 785                         } else if (frp && fra->fr_off <= frp->fr_end) {
 786                                 /* Need to merge in a modified 'frp' */
 787                                 KASSERT((cur == NULL), ("cur != NULL: %s",
 788                                     __FUNCTION__));
 789                                 DPFPRINTF(("fragcache[%d]: adjacent(merge "
 790                                     "%d-%d) %d-%d (%d-%d)\n",
 791                                     h->ip_id, frp->fr_off, frp->fr_end, off,
 792                                     max, fra->fr_off, fra->fr_end));
 793                                 fra->fr_off = frp->fr_off;
 794                                 LIST_REMOVE(frp, fr_next);
 795                                 uma_zfree(V_pf_frent_z, frp);
 796                                 frp = NULL;
 797
 798                         }
 799                 }
 800         }
 801
 802         if (hosed) {
 803                 /*
 804                  * We must keep tracking the overall fragment even when
 805                  * we're going to drop it anyway so that we know when to
 806                  * free the overall descriptor.  Thus we drop the frag late.
 807                  */
 808                 goto drop_fragment;
 809         }
 810
 811
 812  pass:
 813         /* Update maximum data size */
 814         if ((*frag)->fr_max < max)
 815                 (*frag)->fr_max = max;
 816
 817         /* This is the last segment */
 818         if (!mff)
 819                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
 820
 821         /* Check if we are completely reassembled */
 822         if (((*frag)->fr_flags & PFFRAG_SEENLAST) &&
 823             LIST_FIRST(&(*frag)->fr_queue)->fr_off == 0 &&
 824             LIST_FIRST(&(*frag)->fr_queue)->fr_end == (*frag)->fr_max) {
 825                 /* Remove from fragment queue */
 826                 DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id,
 827                     (*frag)->fr_max));
 828                 pf_free_fragment(*frag);
 829                 *frag = NULL;
 830         }
 831
 832         return (m);
 833
 834  no_mem:
 835         *nomem = 1;
 836
 837         /* Still need to pay attention to !IP_MF */
 838         if (!mff && *frag != NULL)
 839                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
 840
 841         m_freem(m);
 842         return (NULL);
 843
 844  drop_fragment:
 845
 846         /* Still need to pay attention to !IP_MF */
 847         if (!mff && *frag != NULL)
 848                 (*frag)->fr_flags |= PFFRAG_SEENLAST;
 849
 850         if (drop) {
 851                 /* This fragment has been deemed bad.  Don't reass */
 852                 if (((*frag)->fr_flags & PFFRAG_DROP) == 0)
 853                         DPFPRINTF(("fragcache[%d]: dropping overall fragment\n",
 854                             h->ip_id));
 855                 (*frag)->fr_flags |= PFFRAG_DROP;
 856         }
 857
 858         m_freem(m);
 859         return (NULL);
 860 }
 861
 862 int
 863 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason,
 864     struct pf_pdesc *pd)
 865 {
 866         struct mbuf             *m = *m0;
 867         struct pf_rule          *r;
 868         struct pf_frent         *frent;
 869         struct pf_fragment      *frag = NULL;
 870         struct ip               *h = mtod(m, struct ip *);
 871         int                      mff = (ntohs(h->ip_off) & IP_MF);
 872         int                      hlen = h->ip_hl << 2;
 873         u_int16_t                fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
 874         u_int16_t                max;
 875         int                      ip_len;
 876         int                      ip_off;
 877         int                      tag = -1;
 878
 879         PF_RULES_RASSERT();
 880
 881         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
 882         while (r != NULL) {
 883                 r->evaluations++;
 884                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
 885                         r = r->skip[PF_SKIP_IFP].ptr;
 886                 else if (r->direction && r->direction != dir)
 887                         r = r->skip[PF_SKIP_DIR].ptr;
 888                 else if (r->af && r->af != AF_INET)
 889                         r = r->skip[PF_SKIP_AF].ptr;
 890                 else if (r->proto && r->proto != h->ip_p)
 891                         r = r->skip[PF_SKIP_PROTO].ptr;
 892                 else if (PF_MISMATCHAW(&r->src.addr,
 893                     (struct pf_addr *)&h->ip_src.s_addr, AF_INET,
 894                     r->src.neg, kif, M_GETFIB(m)))
 895                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
 896                 else if (PF_MISMATCHAW(&r->dst.addr,
 897                     (struct pf_addr *)&h->ip_dst.s_addr, AF_INET,
 898                     r->dst.neg, NULL, M_GETFIB(m)))
 899                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
 900                 else if (r->match_tag && !pf_match_tag(m, r, &tag,
 901                     pd->pf_mtag ? pd->pf_mtag->tag : 0))
 902                         r = TAILQ_NEXT(r, entries);
 903                 else
 904                         break;
 905         }
 906
 907         if (r == NULL || r->action == PF_NOSCRUB)
 908                 return (PF_PASS);
 909         else {
 910                 r->packets[dir == PF_OUT]++;
 911                 r->bytes[dir == PF_OUT] += pd->tot_len;
 912         }
 913
 914         /* Check for illegal packets */
 915         if (hlen < (int)sizeof(struct ip))
 916                 goto drop;
 917
 918         if (hlen > ntohs(h->ip_len))
 919                 goto drop;
 920
 921         /* Clear IP_DF if the rule uses the no-df option */
 922         if (r->rule_flag & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
 923                 u_int16_t ip_off = h->ip_off;
 924
 925                 h->ip_off &= htons(~IP_DF);
 926                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
 927         }
 928
 929         /* We will need other tests here */
 930         if (!fragoff && !mff)
 931                 goto no_fragment;
 932
 933         /* We're dealing with a fragment now. Don't allow fragments
 934          * with IP_DF to enter the cache. If the flag was cleared by
 935          * no-df above, fine. Otherwise drop it.
 936          */
 937         if (h->ip_off & htons(IP_DF)) {
 938                 DPFPRINTF(("IP_DF\n"));
 939                 goto bad;
 940         }
 941
 942         ip_len = ntohs(h->ip_len) - hlen;
 943         ip_off = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
 944
 945         /* All fragments are 8 byte aligned */
 946         if (mff && (ip_len & 0x7)) {
 947                 DPFPRINTF(("mff and %d\n", ip_len));
 948                 goto bad;
 949         }
 950
 951         /* Respect maximum length */
 952         if (fragoff + ip_len > IP_MAXPACKET) {
 953                 DPFPRINTF(("max packet %d\n", fragoff + ip_len));
 954                 goto bad;
 955         }
 956         max = fragoff + ip_len;
 957
 958         if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) {
 959
 960                 /* Fully buffer all of the fragments */
 961                 PF_FRAG_LOCK();
 962                 frag = pf_find_fragment(h, &V_pf_frag_tree);
 963
 964                 /* Check if we saw the last fragment already */
 965                 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
 966                     max > frag->fr_max)
 967                         goto bad;
 968
 969                 /* Get an entry for the fragment queue */
 970                 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 971                 if (frent == NULL) {
 972                         PF_FRAG_UNLOCK();
 973                         REASON_SET(reason, PFRES_MEMORY);
 974                         return (PF_DROP);
 975                 }
 976                 frent->fr_ip = h;
 977                 frent->fr_m = m;
 978
 979                 /* Might return a completely reassembled mbuf, or NULL */
 980                 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
 981                 *m0 = m = pf_reassemble(m0, &frag, frent, mff);
 982                 PF_FRAG_UNLOCK();
 983
 984                 if (m == NULL)
 985                         return (PF_DROP);
 986
 987                 /* use mtag from concatenated mbuf chain */
 988                 pd->pf_mtag = pf_find_mtag(m);
 989 #ifdef DIAGNOSTIC
 990                 if (pd->pf_mtag == NULL) {
 991                         printf("%s: pf_find_mtag returned NULL(1)\n", __func__);
 992                         if ((pd->pf_mtag = pf_get_mtag(m)) == NULL) {
 993                                 m_freem(m);
 994                                 *m0 = NULL;
 995                                 goto no_mem;
 996                         }
 997                 }
 998 #endif
 999                 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
1000                         goto drop;
1001
1002                 h = mtod(m, struct ip *);
1003         } else {
1004                 /* non-buffering fragment cache (drops or masks overlaps) */
1005                 int     nomem = 0;
1006
1007                 if (dir == PF_OUT && pd->pf_mtag->flags & PF_TAG_FRAGCACHE) {
1008                         /*
1009                          * Already passed the fragment cache in the
1010                          * input direction.  If we continued, it would
1011                          * appear to be a dup and would be dropped.
1012                          */
1013                         goto fragment_pass;
1014                 }
1015
1016                 PF_FRAG_LOCK();
1017                 frag = pf_find_fragment(h, &V_pf_cache_tree);
1018
1019                 /* Check if we saw the last fragment already */
1020                 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
1021                     max > frag->fr_max) {
1022                         if (r->rule_flag & PFRULE_FRAGDROP)
1023                                 frag->fr_flags |= PFFRAG_DROP;
1024                         goto bad;
1025                 }
1026
1027                 *m0 = m = pf_fragcache(m0, h, &frag, mff,
1028                     (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem);
1029                 PF_FRAG_UNLOCK();
1030                 if (m == NULL) {
1031                         if (nomem)
1032                                 goto no_mem;
1033                         goto drop;
1034                 }
1035
1036                 /* use mtag from copied and trimmed mbuf chain */
1037                 pd->pf_mtag = pf_find_mtag(m);
1038 #ifdef DIAGNOSTIC
1039                 if (pd->pf_mtag == NULL) {
1040                         printf("%s: pf_find_mtag returned NULL(2)\n", __func__);
1041                         if ((pd->pf_mtag = pf_get_mtag(m)) == NULL) {
1042                                 m_freem(m);
1043                                 *m0 = NULL;
1044                                 goto no_mem;
1045                         }
1046                 }
1047 #endif
1048                 if (dir == PF_IN)
1049                         pd->pf_mtag->flags |= PF_TAG_FRAGCACHE;
1050
1051                 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
1052                         goto drop;
1053                 goto fragment_pass;
1054         }
1055
1056  no_fragment:
1057         /* At this point, only IP_DF is allowed in ip_off */
1058         if (h->ip_off & ~htons(IP_DF)) {
1059                 u_int16_t ip_off = h->ip_off;
1060
1061                 h->ip_off &= htons(IP_DF);
1062                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1063         }
1064
1065         /* not missing a return here */
1066
1067  fragment_pass:
1068         pf_scrub_ip(&m, r->rule_flag, r->min_ttl, r->set_tos);
1069
1070         if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0)
1071                 pd->flags |= PFDESC_IP_REAS;
1072         return (PF_PASS);
1073
1074  no_mem:
1075         REASON_SET(reason, PFRES_MEMORY);
1076         if (r != NULL && r->log)
1077                 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
1078                     1);
1079         return (PF_DROP);
1080
1081  drop:
1082         REASON_SET(reason, PFRES_NORM);
1083         if (r != NULL && r->log)
1084                 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
1085                     1);
1086         return (PF_DROP);
1087
1088  bad:
1089         DPFPRINTF(("dropping bad fragment\n"));
1090
1091         /* Free associated fragments */
1092         if (frag != NULL) {
1093                 pf_free_fragment(frag);
1094                 PF_FRAG_UNLOCK();
1095         }
1096
1097         REASON_SET(reason, PFRES_FRAG);
1098         if (r != NULL && r->log)
1099                 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
1100                     1);
1101
1102         return (PF_DROP);
1103 }
1104 #endif
1105
1106 #ifdef INET6
1107 int
1108 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif,
1109     u_short *reason, struct pf_pdesc *pd)
1110 {
1111         struct mbuf             *m = *m0;
1112         struct pf_rule          *r;
1113         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
1114         int                      off;
1115         struct ip6_ext           ext;
1116         struct ip6_opt           opt;
1117         struct ip6_opt_jumbo     jumbo;
1118         struct ip6_frag          frag;
1119         u_int32_t                jumbolen = 0, plen;
1120         u_int16_t                fragoff = 0;
1121         int                      optend;
1122         int                      ooff;
1123         u_int8_t                 proto;
1124         int                      terminal;
1125
1126         PF_RULES_RASSERT();
1127
1128         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1129         while (r != NULL) {
1130                 r->evaluations++;
1131                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1132                         r = r->skip[PF_SKIP_IFP].ptr;
1133                 else if (r->direction && r->direction != dir)
1134                         r = r->skip[PF_SKIP_DIR].ptr;
1135                 else if (r->af && r->af != AF_INET6)
1136                         r = r->skip[PF_SKIP_AF].ptr;
1137 #if 0 /* header chain! */
1138                 else if (r->proto && r->proto != h->ip6_nxt)
1139                         r = r->skip[PF_SKIP_PROTO].ptr;
1140 #endif
1141                 else if (PF_MISMATCHAW(&r->src.addr,
1142                     (struct pf_addr *)&h->ip6_src, AF_INET6,
1143                     r->src.neg, kif, M_GETFIB(m)))
1144                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1145                 else if (PF_MISMATCHAW(&r->dst.addr,
1146                     (struct pf_addr *)&h->ip6_dst, AF_INET6,
1147                     r->dst.neg, NULL, M_GETFIB(m)))
1148                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1149                 else
1150                         break;
1151         }
1152
1153         if (r == NULL || r->action == PF_NOSCRUB)
1154                 return (PF_PASS);
1155         else {
1156                 r->packets[dir == PF_OUT]++;
1157                 r->bytes[dir == PF_OUT] += pd->tot_len;
1158         }
1159
1160         /* Check for illegal packets */
1161         if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len)
1162                 goto drop;
1163
1164         off = sizeof(struct ip6_hdr);
1165         proto = h->ip6_nxt;
1166         terminal = 0;
1167         do {
1168                 switch (proto) {
1169                 case IPPROTO_FRAGMENT:
1170                         goto fragment;
1171                         break;
1172                 case IPPROTO_AH:
1173                 case IPPROTO_ROUTING:
1174                 case IPPROTO_DSTOPTS:
1175                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1176                             NULL, AF_INET6))
1177                                 goto shortpkt;
1178                         if (proto == IPPROTO_AH)
1179                                 off += (ext.ip6e_len + 2) * 4;
1180                         else
1181                                 off += (ext.ip6e_len + 1) * 8;
1182                         proto = ext.ip6e_nxt;
1183                         break;
1184                 case IPPROTO_HOPOPTS:
1185                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1186                             NULL, AF_INET6))
1187                                 goto shortpkt;
1188                         optend = off + (ext.ip6e_len + 1) * 8;
1189                         ooff = off + sizeof(ext);
1190                         do {
1191                                 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type,
1192                                     sizeof(opt.ip6o_type), NULL, NULL,
1193                                     AF_INET6))
1194                                         goto shortpkt;
1195                                 if (opt.ip6o_type == IP6OPT_PAD1) {
1196                                         ooff++;
1197                                         continue;
1198                                 }
1199                                 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt),
1200                                     NULL, NULL, AF_INET6))
1201                                         goto shortpkt;
1202                                 if (ooff + sizeof(opt) + opt.ip6o_len > optend)
1203                                         goto drop;
1204                                 switch (opt.ip6o_type) {
1205                                 case IP6OPT_JUMBO:
1206                                         if (h->ip6_plen != 0)
1207                                                 goto drop;
1208                                         if (!pf_pull_hdr(m, ooff, &jumbo,
1209                                             sizeof(jumbo), NULL, NULL,
1210                                             AF_INET6))
1211                                                 goto shortpkt;
1212                                         memcpy(&jumbolen, jumbo.ip6oj_jumbo_len,
1213                                             sizeof(jumbolen));
1214                                         jumbolen = ntohl(jumbolen);
1215                                         if (jumbolen <= IPV6_MAXPACKET)
1216                                                 goto drop;
1217                                         if (sizeof(struct ip6_hdr) + jumbolen !=
1218                                             m->m_pkthdr.len)
1219                                                 goto drop;
1220                                         break;
1221                                 default:
1222                                         break;
1223                                 }
1224                                 ooff += sizeof(opt) + opt.ip6o_len;
1225                         } while (ooff < optend);
1226
1227                         off = optend;
1228                         proto = ext.ip6e_nxt;
1229                         break;
1230                 default:
1231                         terminal = 1;
1232                         break;
1233                 }
1234         } while (!terminal);
1235
1236         /* jumbo payload option must be present, or plen > 0 */
1237         if (ntohs(h->ip6_plen) == 0)
1238                 plen = jumbolen;
1239         else
1240                 plen = ntohs(h->ip6_plen);
1241         if (plen == 0)
1242                 goto drop;
1243         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1244                 goto shortpkt;
1245
1246         pf_scrub_ip6(&m, r->min_ttl);
1247
1248         return (PF_PASS);
1249
1250  fragment:
1251         if (ntohs(h->ip6_plen) == 0 || jumbolen)
1252                 goto drop;
1253         plen = ntohs(h->ip6_plen);
1254
1255         if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6))
1256                 goto shortpkt;
1257         fragoff = ntohs(frag.ip6f_offlg & IP6F_OFF_MASK);
1258         if (fragoff + (plen - off - sizeof(frag)) > IPV6_MAXPACKET)
1259                 goto badfrag;
1260
1261         /* do something about it */
1262         /* remember to set pd->flags |= PFDESC_IP_REAS */
1263         return (PF_PASS);
1264
1265  shortpkt:
1266         REASON_SET(reason, PFRES_SHORT);
1267         if (r != NULL && r->log)
1268                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1269                     1);
1270         return (PF_DROP);
1271
1272  drop:
1273         REASON_SET(reason, PFRES_NORM);
1274         if (r != NULL && r->log)
1275                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1276                     1);
1277         return (PF_DROP);
1278
1279  badfrag:
1280         REASON_SET(reason, PFRES_FRAG);
1281         if (r != NULL && r->log)
1282                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1283                     1);
1284         return (PF_DROP);
1285 }
1286 #endif /* INET6 */
1287
1288 int
1289 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff,
1290     int off, void *h, struct pf_pdesc *pd)
1291 {
1292         struct pf_rule  *r, *rm = NULL;
1293         struct tcphdr   *th = pd->hdr.tcp;
1294         int              rewrite = 0;
1295         u_short          reason;
1296         u_int8_t         flags;
1297         sa_family_t      af = pd->af;
1298
1299         PF_RULES_RASSERT();
1300
1301         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1302         while (r != NULL) {
1303                 r->evaluations++;
1304                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1305                         r = r->skip[PF_SKIP_IFP].ptr;
1306                 else if (r->direction && r->direction != dir)
1307                         r = r->skip[PF_SKIP_DIR].ptr;
1308                 else if (r->af && r->af != af)
1309                         r = r->skip[PF_SKIP_AF].ptr;
1310                 else if (r->proto && r->proto != pd->proto)
1311                         r = r->skip[PF_SKIP_PROTO].ptr;
1312                 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af,
1313                     r->src.neg, kif, M_GETFIB(m)))
1314                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1315                 else if (r->src.port_op && !pf_match_port(r->src.port_op,
1316                             r->src.port[0], r->src.port[1], th->th_sport))
1317                         r = r->skip[PF_SKIP_SRC_PORT].ptr;
1318                 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af,
1319                     r->dst.neg, NULL, M_GETFIB(m)))
1320                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1321                 else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
1322                             r->dst.port[0], r->dst.port[1], th->th_dport))
1323                         r = r->skip[PF_SKIP_DST_PORT].ptr;
1324                 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match(
1325                             pf_osfp_fingerprint(pd, m, off, th),
1326                             r->os_fingerprint))
1327                         r = TAILQ_NEXT(r, entries);
1328                 else {
1329                         rm = r;
1330                         break;
1331                 }
1332         }
1333
1334         if (rm == NULL || rm->action == PF_NOSCRUB)
1335                 return (PF_PASS);
1336         else {
1337                 r->packets[dir == PF_OUT]++;
1338                 r->bytes[dir == PF_OUT] += pd->tot_len;
1339         }
1340
1341         if (rm->rule_flag & PFRULE_REASSEMBLE_TCP)
1342                 pd->flags |= PFDESC_TCP_NORM;
1343
1344         flags = th->th_flags;
1345         if (flags & TH_SYN) {
1346                 /* Illegal packet */
1347                 if (flags & TH_RST)
1348                         goto tcp_drop;
1349
1350                 if (flags & TH_FIN)
1351                         flags &= ~TH_FIN;
1352         } else {
1353                 /* Illegal packet */
1354                 if (!(flags & (TH_ACK|TH_RST)))
1355                         goto tcp_drop;
1356         }
1357
1358         if (!(flags & TH_ACK)) {
1359                 /* These flags are only valid if ACK is set */
1360                 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG))
1361                         goto tcp_drop;
1362         }
1363
1364         /* Check for illegal header length */
1365         if (th->th_off < (sizeof(struct tcphdr) >> 2))
1366                 goto tcp_drop;
1367
1368         /* If flags changed, or reserved data set, then adjust */
1369         if (flags != th->th_flags || th->th_x2 != 0) {
1370                 u_int16_t       ov, nv;
1371
1372                 ov = *(u_int16_t *)(&th->th_ack + 1);
1373                 th->th_flags = flags;
1374                 th->th_x2 = 0;
1375                 nv = *(u_int16_t *)(&th->th_ack + 1);
1376
1377                 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, ov, nv, 0);
1378                 rewrite = 1;
1379         }
1380
1381         /* Remove urgent pointer, if TH_URG is not set */
1382         if (!(flags & TH_URG) && th->th_urp) {
1383                 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, th->th_urp,
1384                     0, 0);
1385                 th->th_urp = 0;
1386                 rewrite = 1;
1387         }
1388
1389         /* Process options */
1390         if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af))
1391                 rewrite = 1;
1392
1393         /* copy back packet headers if we sanitized */
1394         if (rewrite)
1395                 m_copyback(m, off, sizeof(*th), (caddr_t)th);
1396
1397         return (PF_PASS);
1398
1399  tcp_drop:
1400         REASON_SET(&reason, PFRES_NORM);
1401         if (rm != NULL && r->log)
1402                 PFLOG_PACKET(kif, m, AF_INET, dir, reason, r, NULL, NULL, pd,
1403                     1);
1404         return (PF_DROP);
1405 }
1406
1407 int
1408 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd,
1409     struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst)
1410 {
1411         u_int32_t tsval, tsecr;
1412         u_int8_t hdr[60];
1413         u_int8_t *opt;
1414
1415         KASSERT((src->scrub == NULL),
1416             ("pf_normalize_tcp_init: src->scrub != NULL"));
1417
1418         src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT);
1419         if (src->scrub == NULL)
1420                 return (1);
1421
1422         switch (pd->af) {
1423 #ifdef INET
1424         case AF_INET: {
1425                 struct ip *h = mtod(m, struct ip *);
1426                 src->scrub->pfss_ttl = h->ip_ttl;
1427                 break;
1428         }
1429 #endif /* INET */
1430 #ifdef INET6
1431         case AF_INET6: {
1432                 struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1433                 src->scrub->pfss_ttl = h->ip6_hlim;
1434                 break;
1435         }
1436 #endif /* INET6 */
1437         }
1438
1439
1440         /*
1441          * All normalizations below are only begun if we see the start of
1442          * the connections.  They must all set an enabled bit in pfss_flags
1443          */
1444         if ((th->th_flags & TH_SYN) == 0)
1445                 return (0);
1446
1447
1448         if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub &&
1449             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1450                 /* Diddle with TCP options */
1451                 int hlen;
1452                 opt = hdr + sizeof(struct tcphdr);
1453                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1454                 while (hlen >= TCPOLEN_TIMESTAMP) {
1455                         switch (*opt) {
1456                         case TCPOPT_EOL:        /* FALLTHROUGH */
1457                         case TCPOPT_NOP:
1458                                 opt++;
1459                                 hlen--;
1460                                 break;
1461                         case TCPOPT_TIMESTAMP:
1462                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1463                                         src->scrub->pfss_flags |=
1464                                             PFSS_TIMESTAMP;
1465                                         src->scrub->pfss_ts_mod =
1466                                             htonl(arc4random());
1467
1468                                         /* note PFSS_PAWS not set yet */
1469                                         memcpy(&tsval, &opt[2],
1470                                             sizeof(u_int32_t));
1471                                         memcpy(&tsecr, &opt[6],
1472                                             sizeof(u_int32_t));
1473                                         src->scrub->pfss_tsval0 = ntohl(tsval);
1474                                         src->scrub->pfss_tsval = ntohl(tsval);
1475                                         src->scrub->pfss_tsecr = ntohl(tsecr);
1476                                         getmicrouptime(&src->scrub->pfss_last);
1477                                 }
1478                                 /* FALLTHROUGH */
1479                         default:
1480                                 hlen -= MAX(opt[1], 2);
1481                                 opt += MAX(opt[1], 2);
1482                                 break;
1483                         }
1484                 }
1485         }
1486
1487         return (0);
1488 }
1489
1490 void
1491 pf_normalize_tcp_cleanup(struct pf_state *state)
1492 {
1493         if (state->src.scrub)
1494                 uma_zfree(V_pf_state_scrub_z, state->src.scrub);
1495         if (state->dst.scrub)
1496                 uma_zfree(V_pf_state_scrub_z, state->dst.scrub);
1497
1498         /* Someday... flush the TCP segment reassembly descriptors. */
1499 }
1500
1501 int
1502 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd,
1503     u_short *reason, struct tcphdr *th, struct pf_state *state,
1504     struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback)
1505 {
1506         struct timeval uptime;
1507         u_int32_t tsval, tsecr;
1508         u_int tsval_from_last;
1509         u_int8_t hdr[60];
1510         u_int8_t *opt;
1511         int copyback = 0;
1512         int got_ts = 0;
1513
1514         KASSERT((src->scrub || dst->scrub),
1515             ("%s: src->scrub && dst->scrub!", __func__));
1516
1517         /*
1518          * Enforce the minimum TTL seen for this connection.  Negate a common
1519          * technique to evade an intrusion detection system and confuse
1520          * firewall state code.
1521          */
1522         switch (pd->af) {
1523 #ifdef INET
1524         case AF_INET: {
1525                 if (src->scrub) {
1526                         struct ip *h = mtod(m, struct ip *);
1527                         if (h->ip_ttl > src->scrub->pfss_ttl)
1528                                 src->scrub->pfss_ttl = h->ip_ttl;
1529                         h->ip_ttl = src->scrub->pfss_ttl;
1530                 }
1531                 break;
1532         }
1533 #endif /* INET */
1534 #ifdef INET6
1535         case AF_INET6: {
1536                 if (src->scrub) {
1537                         struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1538                         if (h->ip6_hlim > src->scrub->pfss_ttl)
1539                                 src->scrub->pfss_ttl = h->ip6_hlim;
1540                         h->ip6_hlim = src->scrub->pfss_ttl;
1541                 }
1542                 break;
1543         }
1544 #endif /* INET6 */
1545         }
1546
1547         if (th->th_off > (sizeof(struct tcphdr) >> 2) &&
1548             ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) ||
1549             (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) &&
1550             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1551                 /* Diddle with TCP options */
1552                 int hlen;
1553                 opt = hdr + sizeof(struct tcphdr);
1554                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1555                 while (hlen >= TCPOLEN_TIMESTAMP) {
1556                         switch (*opt) {
1557                         case TCPOPT_EOL:        /* FALLTHROUGH */
1558                         case TCPOPT_NOP:
1559                                 opt++;
1560                                 hlen--;
1561                                 break;
1562                         case TCPOPT_TIMESTAMP:
1563                                 /* Modulate the timestamps.  Can be used for
1564                                  * NAT detection, OS uptime determination or
1565                                  * reboot detection.
1566                                  */
1567
1568                                 if (got_ts) {
1569                                         /* Huh?  Multiple timestamps!? */
1570                                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1571                                                 DPFPRINTF(("multiple TS??"));
1572                                                 pf_print_state(state);
1573                                                 printf("\n");
1574                                         }
1575                                         REASON_SET(reason, PFRES_TS);
1576                                         return (PF_DROP);
1577                                 }
1578                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1579                                         memcpy(&tsval, &opt[2],
1580                                             sizeof(u_int32_t));
1581                                         if (tsval && src->scrub &&
1582                                             (src->scrub->pfss_flags &
1583                                             PFSS_TIMESTAMP)) {
1584                                                 tsval = ntohl(tsval);
1585                                                 pf_change_proto_a(m, &opt[2],
1586                                                     &th->th_sum,
1587                                                     htonl(tsval +
1588                                                     src->scrub->pfss_ts_mod),
1589                                                     0);
1590                                                 copyback = 1;
1591                                         }
1592
1593                                         /* Modulate TS reply iff valid (!0) */
1594                                         memcpy(&tsecr, &opt[6],
1595                                             sizeof(u_int32_t));
1596                                         if (tsecr && dst->scrub &&
1597                                             (dst->scrub->pfss_flags &
1598                                             PFSS_TIMESTAMP)) {
1599                                                 tsecr = ntohl(tsecr)
1600                                                     - dst->scrub->pfss_ts_mod;
1601                                                 pf_change_proto_a(m, &opt[6],
1602                                                     &th->th_sum, htonl(tsecr),
1603                                                     0);
1604                                                 copyback = 1;
1605                                         }
1606                                         got_ts = 1;
1607                                 }
1608                                 /* FALLTHROUGH */
1609                         default:
1610                                 hlen -= MAX(opt[1], 2);
1611                                 opt += MAX(opt[1], 2);
1612                                 break;
1613                         }
1614                 }
1615                 if (copyback) {
1616                         /* Copyback the options, caller copys back header */
1617                         *writeback = 1;
1618                         m_copyback(m, off + sizeof(struct tcphdr),
1619                             (th->th_off << 2) - sizeof(struct tcphdr), hdr +
1620                             sizeof(struct tcphdr));
1621                 }
1622         }
1623
1624
1625         /*
1626          * Must invalidate PAWS checks on connections idle for too long.
1627          * The fastest allowed timestamp clock is 1ms.  That turns out to
1628          * be about 24 days before it wraps.  XXX Right now our lowerbound
1629          * TS echo check only works for the first 12 days of a connection
1630          * when the TS has exhausted half its 32bit space
1631          */
1632 #define TS_MAX_IDLE     (24*24*60*60)
1633 #define TS_MAX_CONN     (12*24*60*60)   /* XXX remove when better tsecr check */
1634
1635         getmicrouptime(&uptime);
1636         if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) &&
1637             (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE ||
1638             time_uptime - state->creation > TS_MAX_CONN))  {
1639                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1640                         DPFPRINTF(("src idled out of PAWS\n"));
1641                         pf_print_state(state);
1642                         printf("\n");
1643                 }
1644                 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS)
1645                     | PFSS_PAWS_IDLED;
1646         }
1647         if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) &&
1648             uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) {
1649                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1650                         DPFPRINTF(("dst idled out of PAWS\n"));
1651                         pf_print_state(state);
1652                         printf("\n");
1653                 }
1654                 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS)
1655                     | PFSS_PAWS_IDLED;
1656         }
1657
1658         if (got_ts && src->scrub && dst->scrub &&
1659             (src->scrub->pfss_flags & PFSS_PAWS) &&
1660             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1661                 /* Validate that the timestamps are "in-window".
1662                  * RFC1323 describes TCP Timestamp options that allow
1663                  * measurement of RTT (round trip time) and PAWS
1664                  * (protection against wrapped sequence numbers).  PAWS
1665                  * gives us a set of rules for rejecting packets on
1666                  * long fat pipes (packets that were somehow delayed
1667                  * in transit longer than the time it took to send the
1668                  * full TCP sequence space of 4Gb).  We can use these
1669                  * rules and infer a few others that will let us treat
1670                  * the 32bit timestamp and the 32bit echoed timestamp
1671                  * as sequence numbers to prevent a blind attacker from
1672                  * inserting packets into a connection.
1673                  *
1674                  * RFC1323 tells us:
1675                  *  - The timestamp on this packet must be greater than
1676                  *    or equal to the last value echoed by the other
1677                  *    endpoint.  The RFC says those will be discarded
1678                  *    since it is a dup that has already been acked.
1679                  *    This gives us a lowerbound on the timestamp.
1680                  *        timestamp >= other last echoed timestamp
1681                  *  - The timestamp will be less than or equal to
1682                  *    the last timestamp plus the time between the
1683                  *    last packet and now.  The RFC defines the max
1684                  *    clock rate as 1ms.  We will allow clocks to be
1685                  *    up to 10% fast and will allow a total difference
1686                  *    or 30 seconds due to a route change.  And this
1687                  *    gives us an upperbound on the timestamp.
1688                  *        timestamp <= last timestamp + max ticks
1689                  *    We have to be careful here.  Windows will send an
1690                  *    initial timestamp of zero and then initialize it
1691                  *    to a random value after the 3whs; presumably to
1692                  *    avoid a DoS by having to call an expensive RNG
1693                  *    during a SYN flood.  Proof MS has at least one
1694                  *    good security geek.
1695                  *
1696                  *  - The TCP timestamp option must also echo the other
1697                  *    endpoints timestamp.  The timestamp echoed is the
1698                  *    one carried on the earliest unacknowledged segment
1699                  *    on the left edge of the sequence window.  The RFC
1700                  *    states that the host will reject any echoed
1701                  *    timestamps that were larger than any ever sent.
1702                  *    This gives us an upperbound on the TS echo.
1703                  *        tescr <= largest_tsval
1704                  *  - The lowerbound on the TS echo is a little more
1705                  *    tricky to determine.  The other endpoint's echoed
1706                  *    values will not decrease.  But there may be
1707                  *    network conditions that re-order packets and
1708                  *    cause our view of them to decrease.  For now the
1709                  *    only lowerbound we can safely determine is that
1710                  *    the TS echo will never be less than the original
1711                  *    TS.  XXX There is probably a better lowerbound.
1712                  *    Remove TS_MAX_CONN with better lowerbound check.
1713                  *        tescr >= other original TS
1714                  *
1715                  * It is also important to note that the fastest
1716                  * timestamp clock of 1ms will wrap its 32bit space in
1717                  * 24 days.  So we just disable TS checking after 24
1718                  * days of idle time.  We actually must use a 12d
1719                  * connection limit until we can come up with a better
1720                  * lowerbound to the TS echo check.
1721                  */
1722                 struct timeval delta_ts;
1723                 int ts_fudge;
1724
1725
1726                 /*
1727                  * PFTM_TS_DIFF is how many seconds of leeway to allow
1728                  * a host's timestamp.  This can happen if the previous
1729                  * packet got delayed in transit for much longer than
1730                  * this packet.
1731                  */
1732                 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0)
1733                         ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF];
1734
1735                 /* Calculate max ticks since the last timestamp */
1736 #define TS_MAXFREQ      1100            /* RFC max TS freq of 1Khz + 10% skew */
1737 #define TS_MICROSECS    1000000         /* microseconds per second */
1738                 delta_ts = uptime;
1739                 timevalsub(&delta_ts, &src->scrub->pfss_last);
1740                 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ;
1741                 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ);
1742
1743                 if ((src->state >= TCPS_ESTABLISHED &&
1744                     dst->state >= TCPS_ESTABLISHED) &&
1745                     (SEQ_LT(tsval, dst->scrub->pfss_tsecr) ||
1746                     SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) ||
1747                     (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) ||
1748                     SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) {
1749                         /* Bad RFC1323 implementation or an insertion attack.
1750                          *
1751                          * - Solaris 2.6 and 2.7 are known to send another ACK
1752                          *   after the FIN,FIN|ACK,ACK closing that carries
1753                          *   an old timestamp.
1754                          */
1755
1756                         DPFPRINTF(("Timestamp failed %c%c%c%c\n",
1757                             SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ',
1758                             SEQ_GT(tsval, src->scrub->pfss_tsval +
1759                             tsval_from_last) ? '1' : ' ',
1760                             SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ',
1761                             SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' '));
1762                         DPFPRINTF((" tsval: %u  tsecr: %u  +ticks: %u  "
1763                             "idle: %jus %lums\n",
1764                             tsval, tsecr, tsval_from_last,
1765                             (uintmax_t)delta_ts.tv_sec,
1766                             delta_ts.tv_usec / 1000));
1767                         DPFPRINTF((" src->tsval: %u  tsecr: %u\n",
1768                             src->scrub->pfss_tsval, src->scrub->pfss_tsecr));
1769                         DPFPRINTF((" dst->tsval: %u  tsecr: %u  tsval0: %u"
1770                             "\n", dst->scrub->pfss_tsval,
1771                             dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0));
1772                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1773                                 pf_print_state(state);
1774                                 pf_print_flags(th->th_flags);
1775                                 printf("\n");
1776                         }
1777                         REASON_SET(reason, PFRES_TS);
1778                         return (PF_DROP);
1779                 }
1780
1781                 /* XXX I'd really like to require tsecr but it's optional */
1782
1783         } else if (!got_ts && (th->th_flags & TH_RST) == 0 &&
1784             ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED)
1785             || pd->p_len > 0 || (th->th_flags & TH_SYN)) &&
1786             src->scrub && dst->scrub &&
1787             (src->scrub->pfss_flags & PFSS_PAWS) &&
1788             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1789                 /* Didn't send a timestamp.  Timestamps aren't really useful
1790                  * when:
1791                  *  - connection opening or closing (often not even sent).
1792                  *    but we must not let an attacker to put a FIN on a
1793                  *    data packet to sneak it through our ESTABLISHED check.
1794                  *  - on a TCP reset.  RFC suggests not even looking at TS.
1795                  *  - on an empty ACK.  The TS will not be echoed so it will
1796                  *    probably not help keep the RTT calculation in sync and
1797                  *    there isn't as much danger when the sequence numbers
1798                  *    got wrapped.  So some stacks don't include TS on empty
1799                  *    ACKs :-(
1800                  *
1801                  * To minimize the disruption to mostly RFC1323 conformant
1802                  * stacks, we will only require timestamps on data packets.
1803                  *
1804                  * And what do ya know, we cannot require timestamps on data
1805                  * packets.  There appear to be devices that do legitimate
1806                  * TCP connection hijacking.  There are HTTP devices that allow
1807                  * a 3whs (with timestamps) and then buffer the HTTP request.
1808                  * If the intermediate device has the HTTP response cache, it
1809                  * will spoof the response but not bother timestamping its
1810                  * packets.  So we can look for the presence of a timestamp in
1811                  * the first data packet and if there, require it in all future
1812                  * packets.
1813                  */
1814
1815                 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) {
1816                         /*
1817                          * Hey!  Someone tried to sneak a packet in.  Or the
1818                          * stack changed its RFC1323 behavior?!?!
1819                          */
1820                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1821                                 DPFPRINTF(("Did not receive expected RFC1323 "
1822                                     "timestamp\n"));
1823                                 pf_print_state(state);
1824                                 pf_print_flags(th->th_flags);
1825                                 printf("\n");
1826                         }
1827                         REASON_SET(reason, PFRES_TS);
1828                         return (PF_DROP);
1829                 }
1830         }
1831
1832
1833         /*
1834          * We will note if a host sends his data packets with or without
1835          * timestamps.  And require all data packets to contain a timestamp
1836          * if the first does.  PAWS implicitly requires that all data packets be
1837          * timestamped.  But I think there are middle-man devices that hijack
1838          * TCP streams immediately after the 3whs and don't timestamp their
1839          * packets (seen in a WWW accelerator or cache).
1840          */
1841         if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags &
1842             (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) {
1843                 if (got_ts)
1844                         src->scrub->pfss_flags |= PFSS_DATA_TS;
1845                 else {
1846                         src->scrub->pfss_flags |= PFSS_DATA_NOTS;
1847                         if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub &&
1848                             (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) {
1849                                 /* Don't warn if other host rejected RFC1323 */
1850                                 DPFPRINTF(("Broken RFC1323 stack did not "
1851                                     "timestamp data packet. Disabled PAWS "
1852                                     "security.\n"));
1853                                 pf_print_state(state);
1854                                 pf_print_flags(th->th_flags);
1855                                 printf("\n");
1856                         }
1857                 }
1858         }
1859
1860
1861         /*
1862          * Update PAWS values
1863          */
1864         if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags &
1865             (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) {
1866                 getmicrouptime(&src->scrub->pfss_last);
1867                 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) ||
1868                     (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1869                         src->scrub->pfss_tsval = tsval;
1870
1871                 if (tsecr) {
1872                         if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) ||
1873                             (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1874                                 src->scrub->pfss_tsecr = tsecr;
1875
1876                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 &&
1877                             (SEQ_LT(tsval, src->scrub->pfss_tsval0) ||
1878                             src->scrub->pfss_tsval0 == 0)) {
1879                                 /* tsval0 MUST be the lowest timestamp */
1880                                 src->scrub->pfss_tsval0 = tsval;
1881                         }
1882
1883                         /* Only fully initialized after a TS gets echoed */
1884                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0)
1885                                 src->scrub->pfss_flags |= PFSS_PAWS;
1886                 }
1887         }
1888
1889         /* I have a dream....  TCP segment reassembly.... */
1890         return (0);
1891 }
1892
1893 static int
1894 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th,
1895     int off, sa_family_t af)
1896 {
1897         u_int16_t       *mss;
1898         int              thoff;
1899         int              opt, cnt, optlen = 0;
1900         int              rewrite = 0;
1901         u_char           opts[TCP_MAXOLEN];
1902         u_char          *optp = opts;
1903
1904         thoff = th->th_off << 2;
1905         cnt = thoff - sizeof(struct tcphdr);
1906
1907         if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt,
1908             NULL, NULL, af))
1909                 return (rewrite);
1910
1911         for (; cnt > 0; cnt -= optlen, optp += optlen) {
1912                 opt = optp[0];
1913                 if (opt == TCPOPT_EOL)
1914                         break;
1915                 if (opt == TCPOPT_NOP)
1916                         optlen = 1;
1917                 else {
1918                         if (cnt < 2)
1919                                 break;
1920                         optlen = optp[1];
1921                         if (optlen < 2 || optlen > cnt)
1922                                 break;
1923                 }
1924                 switch (opt) {
1925                 case TCPOPT_MAXSEG:
1926                         mss = (u_int16_t *)(optp + 2);
1927                         if ((ntohs(*mss)) > r->max_mss) {
1928                                 th->th_sum = pf_proto_cksum_fixup(m,
1929                                     th->th_sum, *mss, htons(r->max_mss), 0);
1930                                 *mss = htons(r->max_mss);
1931                                 rewrite = 1;
1932                         }
1933                         break;
1934                 default:
1935                         break;
1936                 }
1937         }
1938
1939         if (rewrite)
1940                 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts);
1941
1942         return (rewrite);
1943 }
1944
1945 #ifdef INET
1946 static void
1947 pf_scrub_ip(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos)
1948 {
1949         struct mbuf             *m = *m0;
1950         struct ip               *h = mtod(m, struct ip *);
1951
1952         /* Clear IP_DF if no-df was requested */
1953         if (flags & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
1954                 u_int16_t ip_off = h->ip_off;
1955
1956                 h->ip_off &= htons(~IP_DF);
1957                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1958         }
1959
1960         /* Enforce a minimum ttl, may cause endless packet loops */
1961         if (min_ttl && h->ip_ttl < min_ttl) {
1962                 u_int16_t ip_ttl = h->ip_ttl;
1963
1964                 h->ip_ttl = min_ttl;
1965                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
1966         }
1967
1968         /* Enforce tos */
1969         if (flags & PFRULE_SET_TOS) {
1970                 u_int16_t       ov, nv;
1971
1972                 ov = *(u_int16_t *)h;
1973                 h->ip_tos = tos;
1974                 nv = *(u_int16_t *)h;
1975
1976                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0);
1977         }
1978
1979         /* random-id, but not for fragments */
1980         if (flags & PFRULE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) {
1981                 u_int16_t ip_id = h->ip_id;
1982
1983                 h->ip_id = ip_randomid();
1984                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0);
1985         }
1986 }
1987 #endif /* INET */
1988
1989 #ifdef INET6
1990 static void
1991 pf_scrub_ip6(struct mbuf **m0, u_int8_t min_ttl)
1992 {
1993         struct mbuf             *m = *m0;
1994         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
1995
1996         /* Enforce a minimum ttl, may cause endless packet loops */
1997         if (min_ttl && h->ip6_hlim < min_ttl)
1998                 h->ip6_hlim = min_ttl;
1999 }
2000 #endif