sys/netpfil/pf/pf_norm.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause
   3  *
   4  * Copyright 2001 Niels Provos <provos@citi.umich.edu>
   5  * Copyright 2011 Alexander Bluhm <bluhm@openbsd.org>
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  *
  28  *      $OpenBSD: pf_norm.c,v 1.114 2009/01/29 14:11:45 henning Exp $
  29  */
  30
  31 #include <sys/cdefs.h>
  32 __FBSDID("$FreeBSD$");
  33
  34 #include "opt_inet.h"
  35 #include "opt_inet6.h"
  36 #include "opt_pf.h"
  37
  38 #include <sys/param.h>
  39 #include <sys/kernel.h>
  40 #include <sys/lock.h>
  41 #include <sys/mbuf.h>
  42 #include <sys/mutex.h>
  43 #include <sys/refcount.h>
  44 #include <sys/rwlock.h>
  45 #include <sys/socket.h>
  46
  47 #include <net/if.h>
  48 #include <net/vnet.h>
  49 #include <net/pfvar.h>
  50 #include <net/if_pflog.h>
  51
  52 #include <netinet/in.h>
  53 #include <netinet/ip.h>
  54 #include <netinet/ip_var.h>
  55 #include <netinet6/ip6_var.h>
  56 #include <netinet/tcp.h>
  57 #include <netinet/tcp_fsm.h>
  58 #include <netinet/tcp_seq.h>
  59
  60 #ifdef INET6
  61 #include <netinet/ip6.h>
  62 #endif /* INET6 */
  63
  64 struct pf_frent {
  65         TAILQ_ENTRY(pf_frent)   fr_next;
  66         struct mbuf     *fe_m;
  67         uint16_t        fe_hdrlen;      /* ipv4 header length with ip options
  68                                            ipv6, extension, fragment header */
  69         uint16_t        fe_extoff;      /* last extension header offset or 0 */
  70         uint16_t        fe_len;         /* fragment length */
  71         uint16_t        fe_off;         /* fragment offset */
  72         uint16_t        fe_mff;         /* more fragment flag */
  73 };
  74
  75 struct pf_fragment_cmp {
  76         struct pf_addr  frc_src;
  77         struct pf_addr  frc_dst;
  78         uint32_t        frc_id;
  79         sa_family_t     frc_af;
  80         uint8_t         frc_proto;
  81 };
  82
  83 struct pf_fragment {
  84         struct pf_fragment_cmp  fr_key;
  85 #define fr_src  fr_key.frc_src
  86 #define fr_dst  fr_key.frc_dst
  87 #define fr_id   fr_key.frc_id
  88 #define fr_af   fr_key.frc_af
  89 #define fr_proto        fr_key.frc_proto
  90
  91         RB_ENTRY(pf_fragment) fr_entry;
  92         TAILQ_ENTRY(pf_fragment) frag_next;
  93         uint32_t        fr_timeout;
  94         uint16_t        fr_maxlen;      /* maximum length of single fragment */
  95         TAILQ_HEAD(pf_fragq, pf_frent) fr_queue;
  96 };
  97
  98 struct pf_fragment_tag {
  99         uint16_t        ft_hdrlen;      /* header length of reassembled pkt */
 100         uint16_t        ft_extoff;      /* last extension header offset or 0 */
 101         uint16_t        ft_maxlen;      /* maximum fragment payload length */
 102         uint32_t        ft_id;          /* fragment id */
 103 };
 104
 105 static struct mtx pf_frag_mtx;
 106 MTX_SYSINIT(pf_frag_mtx, &pf_frag_mtx, "pf fragments", MTX_DEF);
 107 #define PF_FRAG_LOCK()          mtx_lock(&pf_frag_mtx)
 108 #define PF_FRAG_UNLOCK()        mtx_unlock(&pf_frag_mtx)
 109 #define PF_FRAG_ASSERT()        mtx_assert(&pf_frag_mtx, MA_OWNED)
 110
 111 VNET_DEFINE(uma_zone_t, pf_state_scrub_z);      /* XXX: shared with pfsync */
 112
 113 static VNET_DEFINE(uma_zone_t, pf_frent_z);
 114 #define V_pf_frent_z    VNET(pf_frent_z)
 115 static VNET_DEFINE(uma_zone_t, pf_frag_z);
 116 #define V_pf_frag_z     VNET(pf_frag_z)
 117
 118 TAILQ_HEAD(pf_fragqueue, pf_fragment);
 119 TAILQ_HEAD(pf_cachequeue, pf_fragment);
 120 static VNET_DEFINE(struct pf_fragqueue, pf_fragqueue);
 121 #define V_pf_fragqueue                  VNET(pf_fragqueue)
 122 RB_HEAD(pf_frag_tree, pf_fragment);
 123 static VNET_DEFINE(struct pf_frag_tree, pf_frag_tree);
 124 #define V_pf_frag_tree                  VNET(pf_frag_tree)
 125 static int               pf_frag_compare(struct pf_fragment *,
 126                             struct pf_fragment *);
 127 static RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 128 static RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 129
 130 static void     pf_flush_fragments(void);
 131 static void     pf_free_fragment(struct pf_fragment *);
 132 static void     pf_remove_fragment(struct pf_fragment *);
 133 static int      pf_normalize_tcpopt(struct pf_rule *, struct mbuf *,
 134                     struct tcphdr *, int, sa_family_t);
 135 static struct pf_frent *pf_create_fragment(u_short *);
 136 static struct pf_fragment *pf_find_fragment(struct pf_fragment_cmp *key,
 137                     struct pf_frag_tree *tree);
 138 static struct pf_fragment *pf_fillup_fragment(struct pf_fragment_cmp *,
 139                     struct pf_frent *, u_short *);
 140 static int      pf_isfull_fragment(struct pf_fragment *);
 141 static struct mbuf *pf_join_fragment(struct pf_fragment *);
 142 #ifdef INET
 143 static void     pf_scrub_ip(struct mbuf **, uint32_t, uint8_t, uint8_t);
 144 static int      pf_reassemble(struct mbuf **, struct ip *, int, u_short *);
 145 #endif  /* INET */
 146 #ifdef INET6
 147 static int      pf_reassemble6(struct mbuf **, struct ip6_hdr *,
 148                     struct ip6_frag *, uint16_t, uint16_t, u_short *);
 149 static void     pf_scrub_ip6(struct mbuf **, uint8_t);
 150 #endif  /* INET6 */
 151
 152 #define DPFPRINTF(x) do {                               \
 153         if (V_pf_status.debug >= PF_DEBUG_MISC) {       \
 154                 printf("%s: ", __func__);               \
 155                 printf x ;                              \
 156         }                                               \
 157 } while(0)
 158
 159 #ifdef INET
 160 static void
 161 pf_ip2key(struct ip *ip, int dir, struct pf_fragment_cmp *key)
 162 {
 163
 164         key->frc_src.v4 = ip->ip_src;
 165         key->frc_dst.v4 = ip->ip_dst;
 166         key->frc_af = AF_INET;
 167         key->frc_proto = ip->ip_p;
 168         key->frc_id = ip->ip_id;
 169 }
 170 #endif  /* INET */
 171
 172 void
 173 pf_normalize_init(void)
 174 {
 175
 176         V_pf_frag_z = uma_zcreate("pf frags", sizeof(struct pf_fragment),
 177             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 178         V_pf_frent_z = uma_zcreate("pf frag entries", sizeof(struct pf_frent),
 179             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 180         V_pf_state_scrub_z = uma_zcreate("pf state scrubs",
 181             sizeof(struct pf_state_scrub),  NULL, NULL, NULL, NULL,
 182             UMA_ALIGN_PTR, 0);
 183
 184         V_pf_limits[PF_LIMIT_FRAGS].zone = V_pf_frent_z;
 185         V_pf_limits[PF_LIMIT_FRAGS].limit = PFFRAG_FRENT_HIWAT;
 186         uma_zone_set_max(V_pf_frent_z, PFFRAG_FRENT_HIWAT);
 187         uma_zone_set_warning(V_pf_frent_z, "PF frag entries limit reached");
 188
 189         TAILQ_INIT(&V_pf_fragqueue);
 190 }
 191
 192 void
 193 pf_normalize_cleanup(void)
 194 {
 195
 196         uma_zdestroy(V_pf_state_scrub_z);
 197         uma_zdestroy(V_pf_frent_z);
 198         uma_zdestroy(V_pf_frag_z);
 199 }
 200
 201 static int
 202 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b)
 203 {
 204         int     diff;
 205
 206         if ((diff = a->fr_id - b->fr_id) != 0)
 207                 return (diff);
 208         if ((diff = a->fr_proto - b->fr_proto) != 0)
 209                 return (diff);
 210         if ((diff = a->fr_af - b->fr_af) != 0)
 211                 return (diff);
 212         if ((diff = pf_addr_cmp(&a->fr_src, &b->fr_src, a->fr_af)) != 0)
 213                 return (diff);
 214         if ((diff = pf_addr_cmp(&a->fr_dst, &b->fr_dst, a->fr_af)) != 0)
 215                 return (diff);
 216         return (0);
 217 }
 218
 219 void
 220 pf_purge_expired_fragments(void)
 221 {
 222         u_int32_t       expire = time_uptime -
 223                             V_pf_default_rule.timeout[PFTM_FRAG];
 224
 225         pf_purge_fragments(expire);
 226 }
 227
 228 void
 229 pf_purge_fragments(uint32_t expire)
 230 {
 231         struct pf_fragment      *frag;
 232
 233         PF_FRAG_LOCK();
 234         while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) {
 235                 if (frag->fr_timeout > expire)
 236                         break;
 237
 238                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 239                 pf_free_fragment(frag);
 240         }
 241
 242         PF_FRAG_UNLOCK();
 243 }
 244
 245 /*
 246  * Try to flush old fragments to make space for new ones
 247  */
 248 static void
 249 pf_flush_fragments(void)
 250 {
 251         struct pf_fragment      *frag;
 252         int                      goal;
 253
 254         PF_FRAG_ASSERT();
 255
 256         goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10;
 257         DPFPRINTF(("trying to free %d frag entriess\n", goal));
 258         while (goal < uma_zone_get_cur(V_pf_frent_z)) {
 259                 frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue);
 260                 if (frag)
 261                         pf_free_fragment(frag);
 262                 else
 263                         break;
 264         }
 265 }
 266
 267 /* Frees the fragments and all associated entries */
 268 static void
 269 pf_free_fragment(struct pf_fragment *frag)
 270 {
 271         struct pf_frent         *frent;
 272
 273         PF_FRAG_ASSERT();
 274
 275         /* Free all fragments */
 276         for (frent = TAILQ_FIRST(&frag->fr_queue); frent;
 277             frent = TAILQ_FIRST(&frag->fr_queue)) {
 278                 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
 279
 280                 m_freem(frent->fe_m);
 281                 uma_zfree(V_pf_frent_z, frent);
 282         }
 283
 284         pf_remove_fragment(frag);
 285 }
 286
 287 static struct pf_fragment *
 288 pf_find_fragment(struct pf_fragment_cmp *key, struct pf_frag_tree *tree)
 289 {
 290         struct pf_fragment      *frag;
 291
 292         PF_FRAG_ASSERT();
 293
 294         frag = RB_FIND(pf_frag_tree, tree, (struct pf_fragment *)key);
 295         if (frag != NULL) {
 296                 /* XXX Are we sure we want to update the timeout? */
 297                 frag->fr_timeout = time_uptime;
 298                 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 299                 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
 300         }
 301
 302         return (frag);
 303 }
 304
 305 /* Removes a fragment from the fragment queue and frees the fragment */
 306 static void
 307 pf_remove_fragment(struct pf_fragment *frag)
 308 {
 309
 310         PF_FRAG_ASSERT();
 311
 312         RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag);
 313         TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 314         uma_zfree(V_pf_frag_z, frag);
 315 }
 316
 317 static struct pf_frent *
 318 pf_create_fragment(u_short *reason)
 319 {
 320         struct pf_frent *frent;
 321
 322         PF_FRAG_ASSERT();
 323
 324         frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 325         if (frent == NULL) {
 326                 pf_flush_fragments();
 327                 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 328                 if (frent == NULL) {
 329                         REASON_SET(reason, PFRES_MEMORY);
 330                         return (NULL);
 331                 }
 332         }
 333
 334         return (frent);
 335 }
 336
 337 static struct pf_fragment *
 338 pf_fillup_fragment(struct pf_fragment_cmp *key, struct pf_frent *frent,
 339                 u_short *reason)
 340 {
 341         struct pf_frent         *after, *next, *prev;
 342         struct pf_fragment      *frag;
 343         uint16_t                total;
 344
 345         PF_FRAG_ASSERT();
 346
 347         /* No empty fragments. */
 348         if (frent->fe_len == 0) {
 349                 DPFPRINTF(("bad fragment: len 0"));
 350                 goto bad_fragment;
 351         }
 352
 353         /* All fragments are 8 byte aligned. */
 354         if (frent->fe_mff && (frent->fe_len & 0x7)) {
 355                 DPFPRINTF(("bad fragment: mff and len %d", frent->fe_len));
 356                 goto bad_fragment;
 357         }
 358
 359         /* Respect maximum length, IP_MAXPACKET == IPV6_MAXPACKET. */
 360         if (frent->fe_off + frent->fe_len > IP_MAXPACKET) {
 361                 DPFPRINTF(("bad fragment: max packet %d",
 362                     frent->fe_off + frent->fe_len));
 363                 goto bad_fragment;
 364         }
 365
 366         DPFPRINTF((key->frc_af == AF_INET ?
 367             "reass frag %d @ %d-%d" : "reass frag %#08x @ %d-%d",
 368             key->frc_id, frent->fe_off, frent->fe_off + frent->fe_len));
 369
 370         /* Fully buffer all of the fragments in this fragment queue. */
 371         frag = pf_find_fragment(key, &V_pf_frag_tree);
 372
 373         /* Create a new reassembly queue for this packet. */
 374         if (frag == NULL) {
 375                 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 376                 if (frag == NULL) {
 377                         pf_flush_fragments();
 378                         frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 379                         if (frag == NULL) {
 380                                 REASON_SET(reason, PFRES_MEMORY);
 381                                 goto drop_fragment;
 382                         }
 383                 }
 384
 385                 *(struct pf_fragment_cmp *)frag = *key;
 386                 frag->fr_timeout = time_uptime;
 387                 frag->fr_maxlen = frent->fe_len;
 388                 TAILQ_INIT(&frag->fr_queue);
 389
 390                 RB_INSERT(pf_frag_tree, &V_pf_frag_tree, frag);
 391                 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
 392
 393                 /* We do not have a previous fragment. */
 394                 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next);
 395
 396                 return (frag);
 397         }
 398
 399         KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue"));
 400
 401         /* Remember maximum fragment len for refragmentation. */
 402         if (frent->fe_len > frag->fr_maxlen)
 403                 frag->fr_maxlen = frent->fe_len;
 404
 405         /* Maximum data we have seen already. */
 406         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 407                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 408
 409         /* Non terminal fragments must have more fragments flag. */
 410         if (frent->fe_off + frent->fe_len < total && !frent->fe_mff)
 411                 goto bad_fragment;
 412
 413         /* Check if we saw the last fragment already. */
 414         if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) {
 415                 if (frent->fe_off + frent->fe_len > total ||
 416                     (frent->fe_off + frent->fe_len == total && frent->fe_mff))
 417                         goto bad_fragment;
 418         } else {
 419                 if (frent->fe_off + frent->fe_len == total && !frent->fe_mff)
 420                         goto bad_fragment;
 421         }
 422
 423         /* Find a fragment after the current one. */
 424         prev = NULL;
 425         TAILQ_FOREACH(after, &frag->fr_queue, fr_next) {
 426                 if (after->fe_off > frent->fe_off)
 427                         break;
 428                 prev = after;
 429         }
 430
 431         KASSERT(prev != NULL || after != NULL,
 432             ("prev != NULL || after != NULL"));
 433
 434         if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) {
 435                 uint16_t precut;
 436
 437                 precut = prev->fe_off + prev->fe_len - frent->fe_off;
 438                 if (precut >= frent->fe_len)
 439                         goto bad_fragment;
 440                 DPFPRINTF(("overlap -%d", precut));
 441                 m_adj(frent->fe_m, precut);
 442                 frent->fe_off += precut;
 443                 frent->fe_len -= precut;
 444         }
 445
 446         for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off;
 447             after = next) {
 448                 uint16_t aftercut;
 449
 450                 aftercut = frent->fe_off + frent->fe_len - after->fe_off;
 451                 DPFPRINTF(("adjust overlap %d", aftercut));
 452                 if (aftercut < after->fe_len) {
 453                         m_adj(after->fe_m, aftercut);
 454                         after->fe_off += aftercut;
 455                         after->fe_len -= aftercut;
 456                         break;
 457                 }
 458
 459                 /* This fragment is completely overlapped, lose it. */
 460                 next = TAILQ_NEXT(after, fr_next);
 461                 m_freem(after->fe_m);
 462                 TAILQ_REMOVE(&frag->fr_queue, after, fr_next);
 463                 uma_zfree(V_pf_frent_z, after);
 464         }
 465
 466         if (prev == NULL)
 467                 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next);
 468         else
 469                 TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next);
 470
 471         return (frag);
 472
 473 bad_fragment:
 474         REASON_SET(reason, PFRES_FRAG);
 475 drop_fragment:
 476         uma_zfree(V_pf_frent_z, frent);
 477         return (NULL);
 478 }
 479
 480 static int
 481 pf_isfull_fragment(struct pf_fragment *frag)
 482 {
 483         struct pf_frent *frent, *next;
 484         uint16_t off, total;
 485
 486         /* Check if we are completely reassembled */
 487         if (TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff)
 488                 return (0);
 489
 490         /* Maximum data we have seen already */
 491         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 492                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 493
 494         /* Check if we have all the data */
 495         off = 0;
 496         for (frent = TAILQ_FIRST(&frag->fr_queue); frent; frent = next) {
 497                 next = TAILQ_NEXT(frent, fr_next);
 498
 499                 off += frent->fe_len;
 500                 if (off < total && (next == NULL || next->fe_off != off)) {
 501                         DPFPRINTF(("missing fragment at %d, next %d, total %d",
 502                             off, next == NULL ? -1 : next->fe_off, total));
 503                         return (0);
 504                 }
 505         }
 506         DPFPRINTF(("%d < %d?", off, total));
 507         if (off < total)
 508                 return (0);
 509         KASSERT(off == total, ("off == total"));
 510
 511         return (1);
 512 }
 513
 514 static struct mbuf *
 515 pf_join_fragment(struct pf_fragment *frag)
 516 {
 517         struct mbuf *m, *m2;
 518         struct pf_frent *frent, *next;
 519
 520         frent = TAILQ_FIRST(&frag->fr_queue);
 521         next = TAILQ_NEXT(frent, fr_next);
 522
 523         m = frent->fe_m;
 524         m_adj(m, (frent->fe_hdrlen + frent->fe_len) - m->m_pkthdr.len);
 525         uma_zfree(V_pf_frent_z, frent);
 526         for (frent = next; frent != NULL; frent = next) {
 527                 next = TAILQ_NEXT(frent, fr_next);
 528
 529                 m2 = frent->fe_m;
 530                 /* Strip off ip header. */
 531                 m_adj(m2, frent->fe_hdrlen);
 532                 /* Strip off any trailing bytes. */
 533                 m_adj(m2, frent->fe_len - m2->m_pkthdr.len);
 534
 535                 uma_zfree(V_pf_frent_z, frent);
 536                 m_cat(m, m2);
 537         }
 538
 539         /* Remove from fragment queue. */
 540         pf_remove_fragment(frag);
 541
 542         return (m);
 543 }
 544
 545 #ifdef INET
 546 static int
 547 pf_reassemble(struct mbuf **m0, struct ip *ip, int dir, u_short *reason)
 548 {
 549         struct mbuf             *m = *m0;
 550         struct pf_frent         *frent;
 551         struct pf_fragment      *frag;
 552         struct pf_fragment_cmp  key;
 553         uint16_t                total, hdrlen;
 554
 555         /* Get an entry for the fragment queue */
 556         if ((frent = pf_create_fragment(reason)) == NULL)
 557                 return (PF_DROP);
 558
 559         frent->fe_m = m;
 560         frent->fe_hdrlen = ip->ip_hl << 2;
 561         frent->fe_extoff = 0;
 562         frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2);
 563         frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3;
 564         frent->fe_mff = ntohs(ip->ip_off) & IP_MF;
 565
 566         pf_ip2key(ip, dir, &key);
 567
 568         if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL)
 569                 return (PF_DROP);
 570
 571         /* The mbuf is part of the fragment entry, no direct free or access */
 572         m = *m0 = NULL;
 573
 574         if (!pf_isfull_fragment(frag))
 575                 return (PF_PASS);  /* drop because *m0 is NULL, no error */
 576
 577         /* We have all the data */
 578         frent = TAILQ_FIRST(&frag->fr_queue);
 579         KASSERT(frent != NULL, ("frent != NULL"));
 580         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 581                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 582         hdrlen = frent->fe_hdrlen;
 583
 584         m = *m0 = pf_join_fragment(frag);
 585         frag = NULL;
 586
 587         if (m->m_flags & M_PKTHDR) {
 588                 int plen = 0;
 589                 for (m = *m0; m; m = m->m_next)
 590                         plen += m->m_len;
 591                 m = *m0;
 592                 m->m_pkthdr.len = plen;
 593         }
 594
 595         ip = mtod(m, struct ip *);
 596         ip->ip_len = htons(hdrlen + total);
 597         ip->ip_off &= ~(IP_MF|IP_OFFMASK);
 598
 599         if (hdrlen + total > IP_MAXPACKET) {
 600                 DPFPRINTF(("drop: too big: %d", total));
 601                 ip->ip_len = 0;
 602                 REASON_SET(reason, PFRES_SHORT);
 603                 /* PF_DROP requires a valid mbuf *m0 in pf_test() */
 604                 return (PF_DROP);
 605         }
 606
 607         DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len)));
 608         return (PF_PASS);
 609 }
 610 #endif  /* INET */
 611
 612 #ifdef INET6
 613 static int
 614 pf_reassemble6(struct mbuf **m0, struct ip6_hdr *ip6, struct ip6_frag *fraghdr,
 615     uint16_t hdrlen, uint16_t extoff, u_short *reason)
 616 {
 617         struct mbuf             *m = *m0;
 618         struct pf_frent         *frent;
 619         struct pf_fragment      *frag;
 620         struct pf_fragment_cmp   key;
 621         struct m_tag            *mtag;
 622         struct pf_fragment_tag  *ftag;
 623         int                      off;
 624         uint32_t                 frag_id;
 625         uint16_t                 total, maxlen;
 626         uint8_t                  proto;
 627
 628         PF_FRAG_LOCK();
 629
 630         /* Get an entry for the fragment queue. */
 631         if ((frent = pf_create_fragment(reason)) == NULL) {
 632                 PF_FRAG_UNLOCK();
 633                 return (PF_DROP);
 634         }
 635
 636         frent->fe_m = m;
 637         frent->fe_hdrlen = hdrlen;
 638         frent->fe_extoff = extoff;
 639         frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen;
 640         frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK);
 641         frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG;
 642
 643         key.frc_src.v6 = ip6->ip6_src;
 644         key.frc_dst.v6 = ip6->ip6_dst;
 645         key.frc_af = AF_INET6;
 646         /* Only the first fragment's protocol is relevant. */
 647         key.frc_proto = 0;
 648         key.frc_id = fraghdr->ip6f_ident;
 649
 650         if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) {
 651                 PF_FRAG_UNLOCK();
 652                 return (PF_DROP);
 653         }
 654
 655         /* The mbuf is part of the fragment entry, no direct free or access. */
 656         m = *m0 = NULL;
 657
 658         if (!pf_isfull_fragment(frag)) {
 659                 PF_FRAG_UNLOCK();
 660                 return (PF_PASS);  /* Drop because *m0 is NULL, no error. */
 661         }
 662
 663         /* We have all the data. */
 664         extoff = frent->fe_extoff;
 665         maxlen = frag->fr_maxlen;
 666         frag_id = frag->fr_id;
 667         frent = TAILQ_FIRST(&frag->fr_queue);
 668         KASSERT(frent != NULL, ("frent != NULL"));
 669         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 670                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 671         hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag);
 672
 673         m = *m0 = pf_join_fragment(frag);
 674         frag = NULL;
 675
 676         PF_FRAG_UNLOCK();
 677
 678         /* Take protocol from first fragment header. */
 679         m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off);
 680         KASSERT(m, ("%s: short mbuf chain", __func__));
 681         proto = *(mtod(m, caddr_t) + off);
 682         m = *m0;
 683
 684         /* Delete frag6 header */
 685         if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0)
 686                 goto fail;
 687
 688         if (m->m_flags & M_PKTHDR) {
 689                 int plen = 0;
 690                 for (m = *m0; m; m = m->m_next)
 691                         plen += m->m_len;
 692                 m = *m0;
 693                 m->m_pkthdr.len = plen;
 694         }
 695
 696         if ((mtag = m_tag_get(PF_REASSEMBLED, sizeof(struct pf_fragment_tag),
 697             M_NOWAIT)) == NULL)
 698                 goto fail;
 699         ftag = (struct pf_fragment_tag *)(mtag + 1);
 700         ftag->ft_hdrlen = hdrlen;
 701         ftag->ft_extoff = extoff;
 702         ftag->ft_maxlen = maxlen;
 703         ftag->ft_id = frag_id;
 704         m_tag_prepend(m, mtag);
 705
 706         ip6 = mtod(m, struct ip6_hdr *);
 707         ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total);
 708         if (extoff) {
 709                 /* Write protocol into next field of last extension header. */
 710                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
 711                     &off);
 712                 KASSERT(m, ("%s: short mbuf chain", __func__));
 713                 *(mtod(m, char *) + off) = proto;
 714                 m = *m0;
 715         } else
 716                 ip6->ip6_nxt = proto;
 717
 718         if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) {
 719                 DPFPRINTF(("drop: too big: %d", total));
 720                 ip6->ip6_plen = 0;
 721                 REASON_SET(reason, PFRES_SHORT);
 722                 /* PF_DROP requires a valid mbuf *m0 in pf_test6(). */
 723                 return (PF_DROP);
 724         }
 725
 726         DPFPRINTF(("complete: %p(%d)", m, ntohs(ip6->ip6_plen)));
 727         return (PF_PASS);
 728
 729 fail:
 730         REASON_SET(reason, PFRES_MEMORY);
 731         /* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */
 732         return (PF_DROP);
 733 }
 734 #endif  /* INET6 */
 735
 736 #ifdef INET6
 737 int
 738 pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag)
 739 {
 740         struct mbuf             *m = *m0, *t;
 741         struct pf_fragment_tag  *ftag = (struct pf_fragment_tag *)(mtag + 1);
 742         struct pf_pdesc          pd;
 743         uint32_t                 frag_id;
 744         uint16_t                 hdrlen, extoff, maxlen;
 745         uint8_t                  proto;
 746         int                      error, action;
 747
 748         hdrlen = ftag->ft_hdrlen;
 749         extoff = ftag->ft_extoff;
 750         maxlen = ftag->ft_maxlen;
 751         frag_id = ftag->ft_id;
 752         m_tag_delete(m, mtag);
 753         mtag = NULL;
 754         ftag = NULL;
 755
 756         if (extoff) {
 757                 int off;
 758
 759                 /* Use protocol from next field of last extension header */
 760                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
 761                     &off);
 762                 KASSERT((m != NULL), ("pf_refragment6: short mbuf chain"));
 763                 proto = *(mtod(m, caddr_t) + off);
 764                 *(mtod(m, char *) + off) = IPPROTO_FRAGMENT;
 765                 m = *m0;
 766         } else {
 767                 struct ip6_hdr *hdr;
 768
 769                 hdr = mtod(m, struct ip6_hdr *);
 770                 proto = hdr->ip6_nxt;
 771                 hdr->ip6_nxt = IPPROTO_FRAGMENT;
 772         }
 773
 774         /* The MTU must be a multiple of 8 bytes, or we risk doing the
 775          * fragmentation wrong. */
 776         maxlen = maxlen & ~7;
 777
 778         /*
 779          * Maxlen may be less than 8 if there was only a single
 780          * fragment.  As it was fragmented before, add a fragment
 781          * header also for a single fragment.  If total or maxlen
 782          * is less than 8, ip6_fragment() will return EMSGSIZE and
 783          * we drop the packet.
 784          */
 785         error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id);
 786         m = (*m0)->m_nextpkt;
 787         (*m0)->m_nextpkt = NULL;
 788         if (error == 0) {
 789                 /* The first mbuf contains the unfragmented packet. */
 790                 m_freem(*m0);
 791                 *m0 = NULL;
 792                 action = PF_PASS;
 793         } else {
 794                 /* Drop expects an mbuf to free. */
 795                 DPFPRINTF(("refragment error %d", error));
 796                 action = PF_DROP;
 797         }
 798         for (t = m; m; m = t) {
 799                 t = m->m_nextpkt;
 800                 m->m_nextpkt = NULL;
 801                 m->m_flags |= M_SKIP_FIREWALL;
 802                 memset(&pd, 0, sizeof(pd));
 803                 pd.pf_mtag = pf_find_mtag(m);
 804                 if (error == 0)
 805                         ip6_forward(m, 0);
 806                 else
 807                         m_freem(m);
 808         }
 809
 810         return (action);
 811 }
 812 #endif /* INET6 */
 813
 814 #ifdef INET
 815 int
 816 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason,
 817     struct pf_pdesc *pd)
 818 {
 819         struct mbuf             *m = *m0;
 820         struct pf_rule          *r;
 821         struct ip               *h = mtod(m, struct ip *);
 822         int                      mff = (ntohs(h->ip_off) & IP_MF);
 823         int                      hlen = h->ip_hl << 2;
 824         u_int16_t                fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
 825         u_int16_t                max;
 826         int                      ip_len;
 827         int                      ip_off;
 828         int                      tag = -1;
 829         int                      verdict;
 830
 831         PF_RULES_RASSERT();
 832
 833         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
 834         while (r != NULL) {
 835                 r->evaluations++;
 836                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
 837                         r = r->skip[PF_SKIP_IFP].ptr;
 838                 else if (r->direction && r->direction != dir)
 839                         r = r->skip[PF_SKIP_DIR].ptr;
 840                 else if (r->af && r->af != AF_INET)
 841                         r = r->skip[PF_SKIP_AF].ptr;
 842                 else if (r->proto && r->proto != h->ip_p)
 843                         r = r->skip[PF_SKIP_PROTO].ptr;
 844                 else if (PF_MISMATCHAW(&r->src.addr,
 845                     (struct pf_addr *)&h->ip_src.s_addr, AF_INET,
 846                     r->src.neg, kif, M_GETFIB(m)))
 847                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
 848                 else if (PF_MISMATCHAW(&r->dst.addr,
 849                     (struct pf_addr *)&h->ip_dst.s_addr, AF_INET,
 850                     r->dst.neg, NULL, M_GETFIB(m)))
 851                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
 852                 else if (r->match_tag && !pf_match_tag(m, r, &tag,
 853                     pd->pf_mtag ? pd->pf_mtag->tag : 0))
 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                 REASON_SET(reason, PFRES_NORM);
 869                 goto drop;
 870         }
 871
 872         if (hlen > ntohs(h->ip_len)) {
 873                 REASON_SET(reason, PFRES_NORM);
 874                 goto drop;
 875         }
 876
 877         /* Clear IP_DF if the rule uses the no-df option */
 878         if (r->rule_flag & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
 879                 u_int16_t ip_off = h->ip_off;
 880
 881                 h->ip_off &= htons(~IP_DF);
 882                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
 883         }
 884
 885         /* We will need other tests here */
 886         if (!fragoff && !mff)
 887                 goto no_fragment;
 888
 889         /* We're dealing with a fragment now. Don't allow fragments
 890          * with IP_DF to enter the cache. If the flag was cleared by
 891          * no-df above, fine. Otherwise drop it.
 892          */
 893         if (h->ip_off & htons(IP_DF)) {
 894                 DPFPRINTF(("IP_DF\n"));
 895                 goto bad;
 896         }
 897
 898         ip_len = ntohs(h->ip_len) - hlen;
 899         ip_off = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
 900
 901         /* All fragments are 8 byte aligned */
 902         if (mff && (ip_len & 0x7)) {
 903                 DPFPRINTF(("mff and %d\n", ip_len));
 904                 goto bad;
 905         }
 906
 907         /* Respect maximum length */
 908         if (fragoff + ip_len > IP_MAXPACKET) {
 909                 DPFPRINTF(("max packet %d\n", fragoff + ip_len));
 910                 goto bad;
 911         }
 912         max = fragoff + ip_len;
 913
 914         /* Fully buffer all of the fragments
 915          * Might return a completely reassembled mbuf, or NULL */
 916         PF_FRAG_LOCK();
 917         DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
 918         verdict = pf_reassemble(m0, h, dir, reason);
 919         PF_FRAG_UNLOCK();
 920
 921         if (verdict != PF_PASS)
 922                 return (PF_DROP);
 923
 924         m = *m0;
 925         if (m == NULL)
 926                 return (PF_DROP);
 927
 928         h = mtod(m, struct ip *);
 929
 930  no_fragment:
 931         /* At this point, only IP_DF is allowed in ip_off */
 932         if (h->ip_off & ~htons(IP_DF)) {
 933                 u_int16_t ip_off = h->ip_off;
 934
 935                 h->ip_off &= htons(IP_DF);
 936                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
 937         }
 938
 939         pf_scrub_ip(&m, r->rule_flag, r->min_ttl, r->set_tos);
 940
 941         return (PF_PASS);
 942
 943  bad:
 944         DPFPRINTF(("dropping bad fragment\n"));
 945         REASON_SET(reason, PFRES_FRAG);
 946  drop:
 947         if (r != NULL && r->log)
 948                 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
 949                     1);
 950
 951         return (PF_DROP);
 952 }
 953 #endif
 954
 955 #ifdef INET6
 956 int
 957 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif,
 958     u_short *reason, struct pf_pdesc *pd)
 959 {
 960         struct mbuf             *m = *m0;
 961         struct pf_rule          *r;
 962         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
 963         int                      extoff;
 964         int                      off;
 965         struct ip6_ext           ext;
 966         struct ip6_opt           opt;
 967         struct ip6_opt_jumbo     jumbo;
 968         struct ip6_frag          frag;
 969         u_int32_t                jumbolen = 0, plen;
 970         int                      optend;
 971         int                      ooff;
 972         u_int8_t                 proto;
 973         int                      terminal;
 974
 975         PF_RULES_RASSERT();
 976
 977         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
 978         while (r != NULL) {
 979                 r->evaluations++;
 980                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
 981                         r = r->skip[PF_SKIP_IFP].ptr;
 982                 else if (r->direction && r->direction != dir)
 983                         r = r->skip[PF_SKIP_DIR].ptr;
 984                 else if (r->af && r->af != AF_INET6)
 985                         r = r->skip[PF_SKIP_AF].ptr;
 986 #if 0 /* header chain! */
 987                 else if (r->proto && r->proto != h->ip6_nxt)
 988                         r = r->skip[PF_SKIP_PROTO].ptr;
 989 #endif
 990                 else if (PF_MISMATCHAW(&r->src.addr,
 991                     (struct pf_addr *)&h->ip6_src, AF_INET6,
 992                     r->src.neg, kif, M_GETFIB(m)))
 993                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
 994                 else if (PF_MISMATCHAW(&r->dst.addr,
 995                     (struct pf_addr *)&h->ip6_dst, AF_INET6,
 996                     r->dst.neg, NULL, M_GETFIB(m)))
 997                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
 998                 else
 999                         break;
1000         }
1001
1002         if (r == NULL || r->action == PF_NOSCRUB)
1003                 return (PF_PASS);
1004         else {
1005                 r->packets[dir == PF_OUT]++;
1006                 r->bytes[dir == PF_OUT] += pd->tot_len;
1007         }
1008
1009         /* Check for illegal packets */
1010         if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len)
1011                 goto drop;
1012
1013         extoff = 0;
1014         off = sizeof(struct ip6_hdr);
1015         proto = h->ip6_nxt;
1016         terminal = 0;
1017         do {
1018                 switch (proto) {
1019                 case IPPROTO_FRAGMENT:
1020                         goto fragment;
1021                         break;
1022                 case IPPROTO_AH:
1023                 case IPPROTO_ROUTING:
1024                 case IPPROTO_DSTOPTS:
1025                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1026                             NULL, AF_INET6))
1027                                 goto shortpkt;
1028                         extoff = off;
1029                         if (proto == IPPROTO_AH)
1030                                 off += (ext.ip6e_len + 2) * 4;
1031                         else
1032                                 off += (ext.ip6e_len + 1) * 8;
1033                         proto = ext.ip6e_nxt;
1034                         break;
1035                 case IPPROTO_HOPOPTS:
1036                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1037                             NULL, AF_INET6))
1038                                 goto shortpkt;
1039                         extoff = off;
1040                         optend = off + (ext.ip6e_len + 1) * 8;
1041                         ooff = off + sizeof(ext);
1042                         do {
1043                                 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type,
1044                                     sizeof(opt.ip6o_type), NULL, NULL,
1045                                     AF_INET6))
1046                                         goto shortpkt;
1047                                 if (opt.ip6o_type == IP6OPT_PAD1) {
1048                                         ooff++;
1049                                         continue;
1050                                 }
1051                                 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt),
1052                                     NULL, NULL, AF_INET6))
1053                                         goto shortpkt;
1054                                 if (ooff + sizeof(opt) + opt.ip6o_len > optend)
1055                                         goto drop;
1056                                 switch (opt.ip6o_type) {
1057                                 case IP6OPT_JUMBO:
1058                                         if (h->ip6_plen != 0)
1059                                                 goto drop;
1060                                         if (!pf_pull_hdr(m, ooff, &jumbo,
1061                                             sizeof(jumbo), NULL, NULL,
1062                                             AF_INET6))
1063                                                 goto shortpkt;
1064                                         memcpy(&jumbolen, jumbo.ip6oj_jumbo_len,
1065                                             sizeof(jumbolen));
1066                                         jumbolen = ntohl(jumbolen);
1067                                         if (jumbolen <= IPV6_MAXPACKET)
1068                                                 goto drop;
1069                                         if (sizeof(struct ip6_hdr) + jumbolen !=
1070                                             m->m_pkthdr.len)
1071                                                 goto drop;
1072                                         break;
1073                                 default:
1074                                         break;
1075                                 }
1076                                 ooff += sizeof(opt) + opt.ip6o_len;
1077                         } while (ooff < optend);
1078
1079                         off = optend;
1080                         proto = ext.ip6e_nxt;
1081                         break;
1082                 default:
1083                         terminal = 1;
1084                         break;
1085                 }
1086         } while (!terminal);
1087
1088         /* jumbo payload option must be present, or plen > 0 */
1089         if (ntohs(h->ip6_plen) == 0)
1090                 plen = jumbolen;
1091         else
1092                 plen = ntohs(h->ip6_plen);
1093         if (plen == 0)
1094                 goto drop;
1095         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1096                 goto shortpkt;
1097
1098         pf_scrub_ip6(&m, r->min_ttl);
1099
1100         return (PF_PASS);
1101
1102  fragment:
1103         /* Jumbo payload packets cannot be fragmented. */
1104         plen = ntohs(h->ip6_plen);
1105         if (plen == 0 || jumbolen)
1106                 goto drop;
1107         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1108                 goto shortpkt;
1109
1110         if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6))
1111                 goto shortpkt;
1112
1113         /* Offset now points to data portion. */
1114         off += sizeof(frag);
1115
1116         /* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */
1117         if (pf_reassemble6(m0, h, &frag, off, extoff, reason) != PF_PASS)
1118                 return (PF_DROP);
1119         m = *m0;
1120         if (m == NULL)
1121                 return (PF_DROP);
1122
1123         pd->flags |= PFDESC_IP_REAS;
1124         return (PF_PASS);
1125
1126  shortpkt:
1127         REASON_SET(reason, PFRES_SHORT);
1128         if (r != NULL && r->log)
1129                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1130                     1);
1131         return (PF_DROP);
1132
1133  drop:
1134         REASON_SET(reason, PFRES_NORM);
1135         if (r != NULL && r->log)
1136                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1137                     1);
1138         return (PF_DROP);
1139 }
1140 #endif /* INET6 */
1141
1142 int
1143 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff,
1144     int off, void *h, struct pf_pdesc *pd)
1145 {
1146         struct pf_rule  *r, *rm = NULL;
1147         struct tcphdr   *th = pd->hdr.tcp;
1148         int              rewrite = 0;
1149         u_short          reason;
1150         u_int8_t         flags;
1151         sa_family_t      af = pd->af;
1152
1153         PF_RULES_RASSERT();
1154
1155         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1156         while (r != NULL) {
1157                 r->evaluations++;
1158                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1159                         r = r->skip[PF_SKIP_IFP].ptr;
1160                 else if (r->direction && r->direction != dir)
1161                         r = r->skip[PF_SKIP_DIR].ptr;
1162                 else if (r->af && r->af != af)
1163                         r = r->skip[PF_SKIP_AF].ptr;
1164                 else if (r->proto && r->proto != pd->proto)
1165                         r = r->skip[PF_SKIP_PROTO].ptr;
1166                 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af,
1167                     r->src.neg, kif, M_GETFIB(m)))
1168                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1169                 else if (r->src.port_op && !pf_match_port(r->src.port_op,
1170                             r->src.port[0], r->src.port[1], th->th_sport))
1171                         r = r->skip[PF_SKIP_SRC_PORT].ptr;
1172                 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af,
1173                     r->dst.neg, NULL, M_GETFIB(m)))
1174                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1175                 else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
1176                             r->dst.port[0], r->dst.port[1], th->th_dport))
1177                         r = r->skip[PF_SKIP_DST_PORT].ptr;
1178                 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match(
1179                             pf_osfp_fingerprint(pd, m, off, th),
1180                             r->os_fingerprint))
1181                         r = TAILQ_NEXT(r, entries);
1182                 else {
1183                         rm = r;
1184                         break;
1185                 }
1186         }
1187
1188         if (rm == NULL || rm->action == PF_NOSCRUB)
1189                 return (PF_PASS);
1190         else {
1191                 r->packets[dir == PF_OUT]++;
1192                 r->bytes[dir == PF_OUT] += pd->tot_len;
1193         }
1194
1195         if (rm->rule_flag & PFRULE_REASSEMBLE_TCP)
1196                 pd->flags |= PFDESC_TCP_NORM;
1197
1198         flags = th->th_flags;
1199         if (flags & TH_SYN) {
1200                 /* Illegal packet */
1201                 if (flags & TH_RST)
1202                         goto tcp_drop;
1203
1204                 if (flags & TH_FIN)
1205                         goto tcp_drop;
1206         } else {
1207                 /* Illegal packet */
1208                 if (!(flags & (TH_ACK|TH_RST)))
1209                         goto tcp_drop;
1210         }
1211
1212         if (!(flags & TH_ACK)) {
1213                 /* These flags are only valid if ACK is set */
1214                 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG))
1215                         goto tcp_drop;
1216         }
1217
1218         /* Check for illegal header length */
1219         if (th->th_off < (sizeof(struct tcphdr) >> 2))
1220                 goto tcp_drop;
1221
1222         /* If flags changed, or reserved data set, then adjust */
1223         if (flags != th->th_flags || th->th_x2 != 0) {
1224                 u_int16_t       ov, nv;
1225
1226                 ov = *(u_int16_t *)(&th->th_ack + 1);
1227                 th->th_flags = flags;
1228                 th->th_x2 = 0;
1229                 nv = *(u_int16_t *)(&th->th_ack + 1);
1230
1231                 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, ov, nv, 0);
1232                 rewrite = 1;
1233         }
1234
1235         /* Remove urgent pointer, if TH_URG is not set */
1236         if (!(flags & TH_URG) && th->th_urp) {
1237                 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, th->th_urp,
1238                     0, 0);
1239                 th->th_urp = 0;
1240                 rewrite = 1;
1241         }
1242
1243         /* Process options */
1244         if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af))
1245                 rewrite = 1;
1246
1247         /* copy back packet headers if we sanitized */
1248         if (rewrite)
1249                 m_copyback(m, off, sizeof(*th), (caddr_t)th);
1250
1251         return (PF_PASS);
1252
1253  tcp_drop:
1254         REASON_SET(&reason, PFRES_NORM);
1255         if (rm != NULL && r->log)
1256                 PFLOG_PACKET(kif, m, AF_INET, dir, reason, r, NULL, NULL, pd,
1257                     1);
1258         return (PF_DROP);
1259 }
1260
1261 int
1262 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd,
1263     struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst)
1264 {
1265         u_int32_t tsval, tsecr;
1266         u_int8_t hdr[60];
1267         u_int8_t *opt;
1268
1269         KASSERT((src->scrub == NULL),
1270             ("pf_normalize_tcp_init: src->scrub != NULL"));
1271
1272         src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT);
1273         if (src->scrub == NULL)
1274                 return (1);
1275
1276         switch (pd->af) {
1277 #ifdef INET
1278         case AF_INET: {
1279                 struct ip *h = mtod(m, struct ip *);
1280                 src->scrub->pfss_ttl = h->ip_ttl;
1281                 break;
1282         }
1283 #endif /* INET */
1284 #ifdef INET6
1285         case AF_INET6: {
1286                 struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1287                 src->scrub->pfss_ttl = h->ip6_hlim;
1288                 break;
1289         }
1290 #endif /* INET6 */
1291         }
1292
1293
1294         /*
1295          * All normalizations below are only begun if we see the start of
1296          * the connections.  They must all set an enabled bit in pfss_flags
1297          */
1298         if ((th->th_flags & TH_SYN) == 0)
1299                 return (0);
1300
1301
1302         if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub &&
1303             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1304                 /* Diddle with TCP options */
1305                 int hlen;
1306                 opt = hdr + sizeof(struct tcphdr);
1307                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1308                 while (hlen >= TCPOLEN_TIMESTAMP) {
1309                         switch (*opt) {
1310                         case TCPOPT_EOL:        /* FALLTHROUGH */
1311                         case TCPOPT_NOP:
1312                                 opt++;
1313                                 hlen--;
1314                                 break;
1315                         case TCPOPT_TIMESTAMP:
1316                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1317                                         src->scrub->pfss_flags |=
1318                                             PFSS_TIMESTAMP;
1319                                         src->scrub->pfss_ts_mod =
1320                                             htonl(arc4random());
1321
1322                                         /* note PFSS_PAWS not set yet */
1323                                         memcpy(&tsval, &opt[2],
1324                                             sizeof(u_int32_t));
1325                                         memcpy(&tsecr, &opt[6],
1326                                             sizeof(u_int32_t));
1327                                         src->scrub->pfss_tsval0 = ntohl(tsval);
1328                                         src->scrub->pfss_tsval = ntohl(tsval);
1329                                         src->scrub->pfss_tsecr = ntohl(tsecr);
1330                                         getmicrouptime(&src->scrub->pfss_last);
1331                                 }
1332                                 /* FALLTHROUGH */
1333                         default:
1334                                 hlen -= MAX(opt[1], 2);
1335                                 opt += MAX(opt[1], 2);
1336                                 break;
1337                         }
1338                 }
1339         }
1340
1341         return (0);
1342 }
1343
1344 void
1345 pf_normalize_tcp_cleanup(struct pf_state *state)
1346 {
1347         if (state->src.scrub)
1348                 uma_zfree(V_pf_state_scrub_z, state->src.scrub);
1349         if (state->dst.scrub)
1350                 uma_zfree(V_pf_state_scrub_z, state->dst.scrub);
1351
1352         /* Someday... flush the TCP segment reassembly descriptors. */
1353 }
1354
1355 int
1356 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd,
1357     u_short *reason, struct tcphdr *th, struct pf_state *state,
1358     struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback)
1359 {
1360         struct timeval uptime;
1361         u_int32_t tsval, tsecr;
1362         u_int tsval_from_last;
1363         u_int8_t hdr[60];
1364         u_int8_t *opt;
1365         int copyback = 0;
1366         int got_ts = 0;
1367
1368         KASSERT((src->scrub || dst->scrub),
1369             ("%s: src->scrub && dst->scrub!", __func__));
1370
1371         /*
1372          * Enforce the minimum TTL seen for this connection.  Negate a common
1373          * technique to evade an intrusion detection system and confuse
1374          * firewall state code.
1375          */
1376         switch (pd->af) {
1377 #ifdef INET
1378         case AF_INET: {
1379                 if (src->scrub) {
1380                         struct ip *h = mtod(m, struct ip *);
1381                         if (h->ip_ttl > src->scrub->pfss_ttl)
1382                                 src->scrub->pfss_ttl = h->ip_ttl;
1383                         h->ip_ttl = src->scrub->pfss_ttl;
1384                 }
1385                 break;
1386         }
1387 #endif /* INET */
1388 #ifdef INET6
1389         case AF_INET6: {
1390                 if (src->scrub) {
1391                         struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1392                         if (h->ip6_hlim > src->scrub->pfss_ttl)
1393                                 src->scrub->pfss_ttl = h->ip6_hlim;
1394                         h->ip6_hlim = src->scrub->pfss_ttl;
1395                 }
1396                 break;
1397         }
1398 #endif /* INET6 */
1399         }
1400
1401         if (th->th_off > (sizeof(struct tcphdr) >> 2) &&
1402             ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) ||
1403             (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) &&
1404             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1405                 /* Diddle with TCP options */
1406                 int hlen;
1407                 opt = hdr + sizeof(struct tcphdr);
1408                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1409                 while (hlen >= TCPOLEN_TIMESTAMP) {
1410                         switch (*opt) {
1411                         case TCPOPT_EOL:        /* FALLTHROUGH */
1412                         case TCPOPT_NOP:
1413                                 opt++;
1414                                 hlen--;
1415                                 break;
1416                         case TCPOPT_TIMESTAMP:
1417                                 /* Modulate the timestamps.  Can be used for
1418                                  * NAT detection, OS uptime determination or
1419                                  * reboot detection.
1420                                  */
1421
1422                                 if (got_ts) {
1423                                         /* Huh?  Multiple timestamps!? */
1424                                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1425                                                 DPFPRINTF(("multiple TS??"));
1426                                                 pf_print_state(state);
1427                                                 printf("\n");
1428                                         }
1429                                         REASON_SET(reason, PFRES_TS);
1430                                         return (PF_DROP);
1431                                 }
1432                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1433                                         memcpy(&tsval, &opt[2],
1434                                             sizeof(u_int32_t));
1435                                         if (tsval && src->scrub &&
1436                                             (src->scrub->pfss_flags &
1437                                             PFSS_TIMESTAMP)) {
1438                                                 tsval = ntohl(tsval);
1439                                                 pf_change_proto_a(m, &opt[2],
1440                                                     &th->th_sum,
1441                                                     htonl(tsval +
1442                                                     src->scrub->pfss_ts_mod),
1443                                                     0);
1444                                                 copyback = 1;
1445                                         }
1446
1447                                         /* Modulate TS reply iff valid (!0) */
1448                                         memcpy(&tsecr, &opt[6],
1449                                             sizeof(u_int32_t));
1450                                         if (tsecr && dst->scrub &&
1451                                             (dst->scrub->pfss_flags &
1452                                             PFSS_TIMESTAMP)) {
1453                                                 tsecr = ntohl(tsecr)
1454                                                     - dst->scrub->pfss_ts_mod;
1455                                                 pf_change_proto_a(m, &opt[6],
1456                                                     &th->th_sum, htonl(tsecr),
1457                                                     0);
1458                                                 copyback = 1;
1459                                         }
1460                                         got_ts = 1;
1461                                 }
1462                                 /* FALLTHROUGH */
1463                         default:
1464                                 hlen -= MAX(opt[1], 2);
1465                                 opt += MAX(opt[1], 2);
1466                                 break;
1467                         }
1468                 }
1469                 if (copyback) {
1470                         /* Copyback the options, caller copys back header */
1471                         *writeback = 1;
1472                         m_copyback(m, off + sizeof(struct tcphdr),
1473                             (th->th_off << 2) - sizeof(struct tcphdr), hdr +
1474                             sizeof(struct tcphdr));
1475                 }
1476         }
1477
1478
1479         /*
1480          * Must invalidate PAWS checks on connections idle for too long.
1481          * The fastest allowed timestamp clock is 1ms.  That turns out to
1482          * be about 24 days before it wraps.  XXX Right now our lowerbound
1483          * TS echo check only works for the first 12 days of a connection
1484          * when the TS has exhausted half its 32bit space
1485          */
1486 #define TS_MAX_IDLE     (24*24*60*60)
1487 #define TS_MAX_CONN     (12*24*60*60)   /* XXX remove when better tsecr check */
1488
1489         getmicrouptime(&uptime);
1490         if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) &&
1491             (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE ||
1492             time_uptime - state->creation > TS_MAX_CONN))  {
1493                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1494                         DPFPRINTF(("src idled out of PAWS\n"));
1495                         pf_print_state(state);
1496                         printf("\n");
1497                 }
1498                 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS)
1499                     | PFSS_PAWS_IDLED;
1500         }
1501         if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) &&
1502             uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) {
1503                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1504                         DPFPRINTF(("dst idled out of PAWS\n"));
1505                         pf_print_state(state);
1506                         printf("\n");
1507                 }
1508                 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS)
1509                     | PFSS_PAWS_IDLED;
1510         }
1511
1512         if (got_ts && src->scrub && dst->scrub &&
1513             (src->scrub->pfss_flags & PFSS_PAWS) &&
1514             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1515                 /* Validate that the timestamps are "in-window".
1516                  * RFC1323 describes TCP Timestamp options that allow
1517                  * measurement of RTT (round trip time) and PAWS
1518                  * (protection against wrapped sequence numbers).  PAWS
1519                  * gives us a set of rules for rejecting packets on
1520                  * long fat pipes (packets that were somehow delayed
1521                  * in transit longer than the time it took to send the
1522                  * full TCP sequence space of 4Gb).  We can use these
1523                  * rules and infer a few others that will let us treat
1524                  * the 32bit timestamp and the 32bit echoed timestamp
1525                  * as sequence numbers to prevent a blind attacker from
1526                  * inserting packets into a connection.
1527                  *
1528                  * RFC1323 tells us:
1529                  *  - The timestamp on this packet must be greater than
1530                  *    or equal to the last value echoed by the other
1531                  *    endpoint.  The RFC says those will be discarded
1532                  *    since it is a dup that has already been acked.
1533                  *    This gives us a lowerbound on the timestamp.
1534                  *        timestamp >= other last echoed timestamp
1535                  *  - The timestamp will be less than or equal to
1536                  *    the last timestamp plus the time between the
1537                  *    last packet and now.  The RFC defines the max
1538                  *    clock rate as 1ms.  We will allow clocks to be
1539                  *    up to 10% fast and will allow a total difference
1540                  *    or 30 seconds due to a route change.  And this
1541                  *    gives us an upperbound on the timestamp.
1542                  *        timestamp <= last timestamp + max ticks
1543                  *    We have to be careful here.  Windows will send an
1544                  *    initial timestamp of zero and then initialize it
1545                  *    to a random value after the 3whs; presumably to
1546                  *    avoid a DoS by having to call an expensive RNG
1547                  *    during a SYN flood.  Proof MS has at least one
1548                  *    good security geek.
1549                  *
1550                  *  - The TCP timestamp option must also echo the other
1551                  *    endpoints timestamp.  The timestamp echoed is the
1552                  *    one carried on the earliest unacknowledged segment
1553                  *    on the left edge of the sequence window.  The RFC
1554                  *    states that the host will reject any echoed
1555                  *    timestamps that were larger than any ever sent.
1556                  *    This gives us an upperbound on the TS echo.
1557                  *        tescr <= largest_tsval
1558                  *  - The lowerbound on the TS echo is a little more
1559                  *    tricky to determine.  The other endpoint's echoed
1560                  *    values will not decrease.  But there may be
1561                  *    network conditions that re-order packets and
1562                  *    cause our view of them to decrease.  For now the
1563                  *    only lowerbound we can safely determine is that
1564                  *    the TS echo will never be less than the original
1565                  *    TS.  XXX There is probably a better lowerbound.
1566                  *    Remove TS_MAX_CONN with better lowerbound check.
1567                  *        tescr >= other original TS
1568                  *
1569                  * It is also important to note that the fastest
1570                  * timestamp clock of 1ms will wrap its 32bit space in
1571                  * 24 days.  So we just disable TS checking after 24
1572                  * days of idle time.  We actually must use a 12d
1573                  * connection limit until we can come up with a better
1574                  * lowerbound to the TS echo check.
1575                  */
1576                 struct timeval delta_ts;
1577                 int ts_fudge;
1578
1579
1580                 /*
1581                  * PFTM_TS_DIFF is how many seconds of leeway to allow
1582                  * a host's timestamp.  This can happen if the previous
1583                  * packet got delayed in transit for much longer than
1584                  * this packet.
1585                  */
1586                 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0)
1587                         ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF];
1588
1589                 /* Calculate max ticks since the last timestamp */
1590 #define TS_MAXFREQ      1100            /* RFC max TS freq of 1Khz + 10% skew */
1591 #define TS_MICROSECS    1000000         /* microseconds per second */
1592                 delta_ts = uptime;
1593                 timevalsub(&delta_ts, &src->scrub->pfss_last);
1594                 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ;
1595                 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ);
1596
1597                 if ((src->state >= TCPS_ESTABLISHED &&
1598                     dst->state >= TCPS_ESTABLISHED) &&
1599                     (SEQ_LT(tsval, dst->scrub->pfss_tsecr) ||
1600                     SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) ||
1601                     (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) ||
1602                     SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) {
1603                         /* Bad RFC1323 implementation or an insertion attack.
1604                          *
1605                          * - Solaris 2.6 and 2.7 are known to send another ACK
1606                          *   after the FIN,FIN|ACK,ACK closing that carries
1607                          *   an old timestamp.
1608                          */
1609
1610                         DPFPRINTF(("Timestamp failed %c%c%c%c\n",
1611                             SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ',
1612                             SEQ_GT(tsval, src->scrub->pfss_tsval +
1613                             tsval_from_last) ? '1' : ' ',
1614                             SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ',
1615                             SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' '));
1616                         DPFPRINTF((" tsval: %u  tsecr: %u  +ticks: %u  "
1617                             "idle: %jus %lums\n",
1618                             tsval, tsecr, tsval_from_last,
1619                             (uintmax_t)delta_ts.tv_sec,
1620                             delta_ts.tv_usec / 1000));
1621                         DPFPRINTF((" src->tsval: %u  tsecr: %u\n",
1622                             src->scrub->pfss_tsval, src->scrub->pfss_tsecr));
1623                         DPFPRINTF((" dst->tsval: %u  tsecr: %u  tsval0: %u"
1624                             "\n", dst->scrub->pfss_tsval,
1625                             dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0));
1626                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1627                                 pf_print_state(state);
1628                                 pf_print_flags(th->th_flags);
1629                                 printf("\n");
1630                         }
1631                         REASON_SET(reason, PFRES_TS);
1632                         return (PF_DROP);
1633                 }
1634
1635                 /* XXX I'd really like to require tsecr but it's optional */
1636
1637         } else if (!got_ts && (th->th_flags & TH_RST) == 0 &&
1638             ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED)
1639             || pd->p_len > 0 || (th->th_flags & TH_SYN)) &&
1640             src->scrub && dst->scrub &&
1641             (src->scrub->pfss_flags & PFSS_PAWS) &&
1642             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1643                 /* Didn't send a timestamp.  Timestamps aren't really useful
1644                  * when:
1645                  *  - connection opening or closing (often not even sent).
1646                  *    but we must not let an attacker to put a FIN on a
1647                  *    data packet to sneak it through our ESTABLISHED check.
1648                  *  - on a TCP reset.  RFC suggests not even looking at TS.
1649                  *  - on an empty ACK.  The TS will not be echoed so it will
1650                  *    probably not help keep the RTT calculation in sync and
1651                  *    there isn't as much danger when the sequence numbers
1652                  *    got wrapped.  So some stacks don't include TS on empty
1653                  *    ACKs :-(
1654                  *
1655                  * To minimize the disruption to mostly RFC1323 conformant
1656                  * stacks, we will only require timestamps on data packets.
1657                  *
1658                  * And what do ya know, we cannot require timestamps on data
1659                  * packets.  There appear to be devices that do legitimate
1660                  * TCP connection hijacking.  There are HTTP devices that allow
1661                  * a 3whs (with timestamps) and then buffer the HTTP request.
1662                  * If the intermediate device has the HTTP response cache, it
1663                  * will spoof the response but not bother timestamping its
1664                  * packets.  So we can look for the presence of a timestamp in
1665                  * the first data packet and if there, require it in all future
1666                  * packets.
1667                  */
1668
1669                 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) {
1670                         /*
1671                          * Hey!  Someone tried to sneak a packet in.  Or the
1672                          * stack changed its RFC1323 behavior?!?!
1673                          */
1674                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1675                                 DPFPRINTF(("Did not receive expected RFC1323 "
1676                                     "timestamp\n"));
1677                                 pf_print_state(state);
1678                                 pf_print_flags(th->th_flags);
1679                                 printf("\n");
1680                         }
1681                         REASON_SET(reason, PFRES_TS);
1682                         return (PF_DROP);
1683                 }
1684         }
1685
1686
1687         /*
1688          * We will note if a host sends his data packets with or without
1689          * timestamps.  And require all data packets to contain a timestamp
1690          * if the first does.  PAWS implicitly requires that all data packets be
1691          * timestamped.  But I think there are middle-man devices that hijack
1692          * TCP streams immediately after the 3whs and don't timestamp their
1693          * packets (seen in a WWW accelerator or cache).
1694          */
1695         if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags &
1696             (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) {
1697                 if (got_ts)
1698                         src->scrub->pfss_flags |= PFSS_DATA_TS;
1699                 else {
1700                         src->scrub->pfss_flags |= PFSS_DATA_NOTS;
1701                         if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub &&
1702                             (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) {
1703                                 /* Don't warn if other host rejected RFC1323 */
1704                                 DPFPRINTF(("Broken RFC1323 stack did not "
1705                                     "timestamp data packet. Disabled PAWS "
1706                                     "security.\n"));
1707                                 pf_print_state(state);
1708                                 pf_print_flags(th->th_flags);
1709                                 printf("\n");
1710                         }
1711                 }
1712         }
1713
1714
1715         /*
1716          * Update PAWS values
1717          */
1718         if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags &
1719             (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) {
1720                 getmicrouptime(&src->scrub->pfss_last);
1721                 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) ||
1722                     (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1723                         src->scrub->pfss_tsval = tsval;
1724
1725                 if (tsecr) {
1726                         if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) ||
1727                             (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1728                                 src->scrub->pfss_tsecr = tsecr;
1729
1730                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 &&
1731                             (SEQ_LT(tsval, src->scrub->pfss_tsval0) ||
1732                             src->scrub->pfss_tsval0 == 0)) {
1733                                 /* tsval0 MUST be the lowest timestamp */
1734                                 src->scrub->pfss_tsval0 = tsval;
1735                         }
1736
1737                         /* Only fully initialized after a TS gets echoed */
1738                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0)
1739                                 src->scrub->pfss_flags |= PFSS_PAWS;
1740                 }
1741         }
1742
1743         /* I have a dream....  TCP segment reassembly.... */
1744         return (0);
1745 }
1746
1747 static int
1748 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th,
1749     int off, sa_family_t af)
1750 {
1751         u_int16_t       *mss;
1752         int              thoff;
1753         int              opt, cnt, optlen = 0;
1754         int              rewrite = 0;
1755         u_char           opts[TCP_MAXOLEN];
1756         u_char          *optp = opts;
1757
1758         thoff = th->th_off << 2;
1759         cnt = thoff - sizeof(struct tcphdr);
1760
1761         if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt,
1762             NULL, NULL, af))
1763                 return (rewrite);
1764
1765         for (; cnt > 0; cnt -= optlen, optp += optlen) {
1766                 opt = optp[0];
1767                 if (opt == TCPOPT_EOL)
1768                         break;
1769                 if (opt == TCPOPT_NOP)
1770                         optlen = 1;
1771                 else {
1772                         if (cnt < 2)
1773                                 break;
1774                         optlen = optp[1];
1775                         if (optlen < 2 || optlen > cnt)
1776                                 break;
1777                 }
1778                 switch (opt) {
1779                 case TCPOPT_MAXSEG:
1780                         mss = (u_int16_t *)(optp + 2);
1781                         if ((ntohs(*mss)) > r->max_mss) {
1782                                 th->th_sum = pf_proto_cksum_fixup(m,
1783                                     th->th_sum, *mss, htons(r->max_mss), 0);
1784                                 *mss = htons(r->max_mss);
1785                                 rewrite = 1;
1786                         }
1787                         break;
1788                 default:
1789                         break;
1790                 }
1791         }
1792
1793         if (rewrite)
1794                 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts);
1795
1796         return (rewrite);
1797 }
1798
1799 #ifdef INET
1800 static void
1801 pf_scrub_ip(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos)
1802 {
1803         struct mbuf             *m = *m0;
1804         struct ip               *h = mtod(m, struct ip *);
1805
1806         /* Clear IP_DF if no-df was requested */
1807         if (flags & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
1808                 u_int16_t ip_off = h->ip_off;
1809
1810                 h->ip_off &= htons(~IP_DF);
1811                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1812         }
1813
1814         /* Enforce a minimum ttl, may cause endless packet loops */
1815         if (min_ttl && h->ip_ttl < min_ttl) {
1816                 u_int16_t ip_ttl = h->ip_ttl;
1817
1818                 h->ip_ttl = min_ttl;
1819                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
1820         }
1821
1822         /* Enforce tos */
1823         if (flags & PFRULE_SET_TOS) {
1824                 u_int16_t       ov, nv;
1825
1826                 ov = *(u_int16_t *)h;
1827                 h->ip_tos = tos | (h->ip_tos & IPTOS_ECN_MASK);
1828                 nv = *(u_int16_t *)h;
1829
1830                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0);
1831         }
1832
1833         /* random-id, but not for fragments */
1834         if (flags & PFRULE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) {
1835                 uint16_t ip_id = h->ip_id;
1836
1837                 ip_fillid(h);
1838                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0);
1839         }
1840 }
1841 #endif /* INET */
1842
1843 #ifdef INET6
1844 static void
1845 pf_scrub_ip6(struct mbuf **m0, u_int8_t min_ttl)
1846 {
1847         struct mbuf             *m = *m0;
1848         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
1849
1850         /* Enforce a minimum ttl, may cause endless packet loops */
1851         if (min_ttl && h->ip6_hlim < min_ttl)
1852                 h->ip6_hlim = min_ttl;
1853 }
1854 #endif