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/socket.h>
  45
  46 #include <net/if.h>
  47 #include <net/vnet.h>
  48 #include <net/pfvar.h>
  49 #include <net/if_pflog.h>
  50
  51 #include <netinet/in.h>
  52 #include <netinet/ip.h>
  53 #include <netinet/ip_var.h>
  54 #include <netinet6/ip6_var.h>
  55 #include <netinet/tcp.h>
  56 #include <netinet/tcp_fsm.h>
  57 #include <netinet/tcp_seq.h>
  58
  59 #ifdef INET6
  60 #include <netinet/ip6.h>
  61 #endif /* INET6 */
  62
  63 struct pf_frent {
  64         TAILQ_ENTRY(pf_frent)   fr_next;
  65         struct mbuf     *fe_m;
  66         uint16_t        fe_hdrlen;      /* ipv4 header length with ip options
  67                                            ipv6, extension, fragment header */
  68         uint16_t        fe_extoff;      /* last extension header offset or 0 */
  69         uint16_t        fe_len;         /* fragment length */
  70         uint16_t        fe_off;         /* fragment offset */
  71         uint16_t        fe_mff;         /* more fragment flag */
  72 };
  73
  74 struct pf_fragment_cmp {
  75         struct pf_addr  frc_src;
  76         struct pf_addr  frc_dst;
  77         uint32_t        frc_id;
  78         sa_family_t     frc_af;
  79         uint8_t         frc_proto;
  80 };
  81
  82 struct pf_fragment {
  83         struct pf_fragment_cmp  fr_key;
  84 #define fr_src  fr_key.frc_src
  85 #define fr_dst  fr_key.frc_dst
  86 #define fr_id   fr_key.frc_id
  87 #define fr_af   fr_key.frc_af
  88 #define fr_proto        fr_key.frc_proto
  89
  90         RB_ENTRY(pf_fragment) fr_entry;
  91         TAILQ_ENTRY(pf_fragment) frag_next;
  92         uint32_t        fr_timeout;
  93         uint16_t        fr_maxlen;      /* maximum length of single fragment */
  94         TAILQ_HEAD(pf_fragq, pf_frent) fr_queue;
  95 };
  96
  97 struct pf_fragment_tag {
  98         uint16_t        ft_hdrlen;      /* header length of reassembled pkt */
  99         uint16_t        ft_extoff;      /* last extension header offset or 0 */
 100         uint16_t        ft_maxlen;      /* maximum fragment payload length */
 101         uint32_t        ft_id;          /* fragment id */
 102 };
 103
 104 static struct mtx pf_frag_mtx;
 105 MTX_SYSINIT(pf_frag_mtx, &pf_frag_mtx, "pf fragments", MTX_DEF);
 106 #define PF_FRAG_LOCK()          mtx_lock(&pf_frag_mtx)
 107 #define PF_FRAG_UNLOCK()        mtx_unlock(&pf_frag_mtx)
 108 #define PF_FRAG_ASSERT()        mtx_assert(&pf_frag_mtx, MA_OWNED)
 109
 110 VNET_DEFINE(uma_zone_t, pf_state_scrub_z);      /* XXX: shared with pfsync */
 111
 112 static VNET_DEFINE(uma_zone_t, pf_frent_z);
 113 #define V_pf_frent_z    VNET(pf_frent_z)
 114 static VNET_DEFINE(uma_zone_t, pf_frag_z);
 115 #define V_pf_frag_z     VNET(pf_frag_z)
 116
 117 TAILQ_HEAD(pf_fragqueue, pf_fragment);
 118 TAILQ_HEAD(pf_cachequeue, pf_fragment);
 119 static VNET_DEFINE(struct pf_fragqueue, pf_fragqueue);
 120 #define V_pf_fragqueue                  VNET(pf_fragqueue)
 121 RB_HEAD(pf_frag_tree, pf_fragment);
 122 static VNET_DEFINE(struct pf_frag_tree, pf_frag_tree);
 123 #define V_pf_frag_tree                  VNET(pf_frag_tree)
 124 static int               pf_frag_compare(struct pf_fragment *,
 125                             struct pf_fragment *);
 126 static RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 127 static RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
 128
 129 static void     pf_flush_fragments(void);
 130 static void     pf_free_fragment(struct pf_fragment *);
 131 static void     pf_remove_fragment(struct pf_fragment *);
 132 static int      pf_normalize_tcpopt(struct pf_rule *, struct mbuf *,
 133                     struct tcphdr *, int, sa_family_t);
 134 static struct pf_frent *pf_create_fragment(u_short *);
 135 static struct pf_fragment *pf_find_fragment(struct pf_fragment_cmp *key,
 136                     struct pf_frag_tree *tree);
 137 static struct pf_fragment *pf_fillup_fragment(struct pf_fragment_cmp *,
 138                     struct pf_frent *, u_short *);
 139 static int      pf_isfull_fragment(struct pf_fragment *);
 140 static struct mbuf *pf_join_fragment(struct pf_fragment *);
 141 #ifdef INET
 142 static void     pf_scrub_ip(struct mbuf **, uint32_t, uint8_t, uint8_t);
 143 static int      pf_reassemble(struct mbuf **, struct ip *, int, u_short *);
 144 #endif  /* INET */
 145 #ifdef INET6
 146 static int      pf_reassemble6(struct mbuf **, struct ip6_hdr *,
 147                     struct ip6_frag *, uint16_t, uint16_t, u_short *);
 148 static void     pf_scrub_ip6(struct mbuf **, uint8_t);
 149 #endif  /* INET6 */
 150
 151 #define DPFPRINTF(x) do {                               \
 152         if (V_pf_status.debug >= PF_DEBUG_MISC) {       \
 153                 printf("%s: ", __func__);               \
 154                 printf x ;                              \
 155         }                                               \
 156 } while(0)
 157
 158 #ifdef INET
 159 static void
 160 pf_ip2key(struct ip *ip, int dir, struct pf_fragment_cmp *key)
 161 {
 162
 163         key->frc_src.v4 = ip->ip_src;
 164         key->frc_dst.v4 = ip->ip_dst;
 165         key->frc_af = AF_INET;
 166         key->frc_proto = ip->ip_p;
 167         key->frc_id = ip->ip_id;
 168 }
 169 #endif  /* INET */
 170
 171 void
 172 pf_normalize_init(void)
 173 {
 174
 175         V_pf_frag_z = uma_zcreate("pf frags", sizeof(struct pf_fragment),
 176             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 177         V_pf_frent_z = uma_zcreate("pf frag entries", sizeof(struct pf_frent),
 178             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 179         V_pf_state_scrub_z = uma_zcreate("pf state scrubs",
 180             sizeof(struct pf_state_scrub),  NULL, NULL, NULL, NULL,
 181             UMA_ALIGN_PTR, 0);
 182
 183         V_pf_limits[PF_LIMIT_FRAGS].zone = V_pf_frent_z;
 184         V_pf_limits[PF_LIMIT_FRAGS].limit = PFFRAG_FRENT_HIWAT;
 185         uma_zone_set_max(V_pf_frent_z, PFFRAG_FRENT_HIWAT);
 186         uma_zone_set_warning(V_pf_frent_z, "PF frag entries limit reached");
 187
 188         TAILQ_INIT(&V_pf_fragqueue);
 189 }
 190
 191 void
 192 pf_normalize_cleanup(void)
 193 {
 194
 195         uma_zdestroy(V_pf_state_scrub_z);
 196         uma_zdestroy(V_pf_frent_z);
 197         uma_zdestroy(V_pf_frag_z);
 198 }
 199
 200 static int
 201 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b)
 202 {
 203         int     diff;
 204
 205         if ((diff = a->fr_id - b->fr_id) != 0)
 206                 return (diff);
 207         if ((diff = a->fr_proto - b->fr_proto) != 0)
 208                 return (diff);
 209         if ((diff = a->fr_af - b->fr_af) != 0)
 210                 return (diff);
 211         if ((diff = pf_addr_cmp(&a->fr_src, &b->fr_src, a->fr_af)) != 0)
 212                 return (diff);
 213         if ((diff = pf_addr_cmp(&a->fr_dst, &b->fr_dst, a->fr_af)) != 0)
 214                 return (diff);
 215         return (0);
 216 }
 217
 218 void
 219 pf_purge_expired_fragments(void)
 220 {
 221         u_int32_t       expire = time_uptime -
 222                             V_pf_default_rule.timeout[PFTM_FRAG];
 223
 224         pf_purge_fragments(expire);
 225 }
 226
 227 void
 228 pf_purge_fragments(uint32_t expire)
 229 {
 230         struct pf_fragment      *frag;
 231
 232         PF_FRAG_LOCK();
 233         while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) {
 234                 if (frag->fr_timeout > expire)
 235                         break;
 236
 237                 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
 238                 pf_free_fragment(frag);
 239         }
 240
 241         PF_FRAG_UNLOCK();
 242 }
 243
 244 /*
 245  * Try to flush old fragments to make space for new ones
 246  */
 247 static void
 248 pf_flush_fragments(void)
 249 {
 250         struct pf_fragment      *frag;
 251         int                      goal;
 252
 253         PF_FRAG_ASSERT();
 254
 255         goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10;
 256         DPFPRINTF(("trying to free %d frag entriess\n", goal));
 257         while (goal < uma_zone_get_cur(V_pf_frent_z)) {
 258                 frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue);
 259                 if (frag)
 260                         pf_free_fragment(frag);
 261                 else
 262                         break;
 263         }
 264 }
 265
 266 /* Frees the fragments and all associated entries */
 267 static void
 268 pf_free_fragment(struct pf_fragment *frag)
 269 {
 270         struct pf_frent         *frent;
 271
 272         PF_FRAG_ASSERT();
 273
 274         /* Free all fragments */
 275         for (frent = TAILQ_FIRST(&frag->fr_queue); frent;
 276             frent = TAILQ_FIRST(&frag->fr_queue)) {
 277                 TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
 278
 279                 m_freem(frent->fe_m);
 280                 uma_zfree(V_pf_frent_z, frent);
 281         }
 282
 283         pf_remove_fragment(frag);
 284 }
 285
 286 static struct pf_fragment *
 287 pf_find_fragment(struct pf_fragment_cmp *key, struct pf_frag_tree *tree)
 288 {
 289         struct pf_fragment      *frag;
 290
 291         PF_FRAG_ASSERT();
 292
 293         frag = RB_FIND(pf_frag_tree, tree, (struct pf_fragment *)key);
 294         if (frag != NULL) {
 295                 /* XXX Are we sure we want to update the timeout? */
 296                 frag->fr_timeout = time_uptime;
 297                 TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 298                 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
 299         }
 300
 301         return (frag);
 302 }
 303
 304 /* Removes a fragment from the fragment queue and frees the fragment */
 305 static void
 306 pf_remove_fragment(struct pf_fragment *frag)
 307 {
 308
 309         PF_FRAG_ASSERT();
 310
 311         RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag);
 312         TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
 313         uma_zfree(V_pf_frag_z, frag);
 314 }
 315
 316 static struct pf_frent *
 317 pf_create_fragment(u_short *reason)
 318 {
 319         struct pf_frent *frent;
 320
 321         PF_FRAG_ASSERT();
 322
 323         frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 324         if (frent == NULL) {
 325                 pf_flush_fragments();
 326                 frent = uma_zalloc(V_pf_frent_z, M_NOWAIT);
 327                 if (frent == NULL) {
 328                         REASON_SET(reason, PFRES_MEMORY);
 329                         return (NULL);
 330                 }
 331         }
 332
 333         return (frent);
 334 }
 335
 336 static struct pf_fragment *
 337 pf_fillup_fragment(struct pf_fragment_cmp *key, struct pf_frent *frent,
 338                 u_short *reason)
 339 {
 340         struct pf_frent         *after, *next, *prev;
 341         struct pf_fragment      *frag;
 342         uint16_t                total;
 343
 344         PF_FRAG_ASSERT();
 345
 346         /* No empty fragments. */
 347         if (frent->fe_len == 0) {
 348                 DPFPRINTF(("bad fragment: len 0"));
 349                 goto bad_fragment;
 350         }
 351
 352         /* All fragments are 8 byte aligned. */
 353         if (frent->fe_mff && (frent->fe_len & 0x7)) {
 354                 DPFPRINTF(("bad fragment: mff and len %d", frent->fe_len));
 355                 goto bad_fragment;
 356         }
 357
 358         /* Respect maximum length, IP_MAXPACKET == IPV6_MAXPACKET. */
 359         if (frent->fe_off + frent->fe_len > IP_MAXPACKET) {
 360                 DPFPRINTF(("bad fragment: max packet %d",
 361                     frent->fe_off + frent->fe_len));
 362                 goto bad_fragment;
 363         }
 364
 365         DPFPRINTF((key->frc_af == AF_INET ?
 366             "reass frag %d @ %d-%d" : "reass frag %#08x @ %d-%d",
 367             key->frc_id, frent->fe_off, frent->fe_off + frent->fe_len));
 368
 369         /* Fully buffer all of the fragments in this fragment queue. */
 370         frag = pf_find_fragment(key, &V_pf_frag_tree);
 371
 372         /* Create a new reassembly queue for this packet. */
 373         if (frag == NULL) {
 374                 frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 375                 if (frag == NULL) {
 376                         pf_flush_fragments();
 377                         frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
 378                         if (frag == NULL) {
 379                                 REASON_SET(reason, PFRES_MEMORY);
 380                                 goto drop_fragment;
 381                         }
 382                 }
 383
 384                 *(struct pf_fragment_cmp *)frag = *key;
 385                 frag->fr_timeout = time_uptime;
 386                 frag->fr_maxlen = frent->fe_len;
 387                 TAILQ_INIT(&frag->fr_queue);
 388
 389                 RB_INSERT(pf_frag_tree, &V_pf_frag_tree, frag);
 390                 TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
 391
 392                 /* We do not have a previous fragment. */
 393                 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next);
 394
 395                 return (frag);
 396         }
 397
 398         KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue"));
 399
 400         /* Remember maximum fragment len for refragmentation. */
 401         if (frent->fe_len > frag->fr_maxlen)
 402                 frag->fr_maxlen = frent->fe_len;
 403
 404         /* Maximum data we have seen already. */
 405         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 406                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 407
 408         /* Non terminal fragments must have more fragments flag. */
 409         if (frent->fe_off + frent->fe_len < total && !frent->fe_mff)
 410                 goto bad_fragment;
 411
 412         /* Check if we saw the last fragment already. */
 413         if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) {
 414                 if (frent->fe_off + frent->fe_len > total ||
 415                     (frent->fe_off + frent->fe_len == total && frent->fe_mff))
 416                         goto bad_fragment;
 417         } else {
 418                 if (frent->fe_off + frent->fe_len == total && !frent->fe_mff)
 419                         goto bad_fragment;
 420         }
 421
 422         /* Find a fragment after the current one. */
 423         prev = NULL;
 424         TAILQ_FOREACH(after, &frag->fr_queue, fr_next) {
 425                 if (after->fe_off > frent->fe_off)
 426                         break;
 427                 prev = after;
 428         }
 429
 430         KASSERT(prev != NULL || after != NULL,
 431             ("prev != NULL || after != NULL"));
 432
 433         if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) {
 434                 uint16_t precut;
 435
 436                 precut = prev->fe_off + prev->fe_len - frent->fe_off;
 437                 if (precut >= frent->fe_len)
 438                         goto bad_fragment;
 439                 DPFPRINTF(("overlap -%d", precut));
 440                 m_adj(frent->fe_m, precut);
 441                 frent->fe_off += precut;
 442                 frent->fe_len -= precut;
 443         }
 444
 445         for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off;
 446             after = next) {
 447                 uint16_t aftercut;
 448
 449                 aftercut = frent->fe_off + frent->fe_len - after->fe_off;
 450                 DPFPRINTF(("adjust overlap %d", aftercut));
 451                 if (aftercut < after->fe_len) {
 452                         m_adj(after->fe_m, aftercut);
 453                         after->fe_off += aftercut;
 454                         after->fe_len -= aftercut;
 455                         break;
 456                 }
 457
 458                 /* This fragment is completely overlapped, lose it. */
 459                 next = TAILQ_NEXT(after, fr_next);
 460                 m_freem(after->fe_m);
 461                 TAILQ_REMOVE(&frag->fr_queue, after, fr_next);
 462                 uma_zfree(V_pf_frent_z, after);
 463         }
 464
 465         if (prev == NULL)
 466                 TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next);
 467         else
 468                 TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next);
 469
 470         return (frag);
 471
 472 bad_fragment:
 473         REASON_SET(reason, PFRES_FRAG);
 474 drop_fragment:
 475         uma_zfree(V_pf_frent_z, frent);
 476         return (NULL);
 477 }
 478
 479 static int
 480 pf_isfull_fragment(struct pf_fragment *frag)
 481 {
 482         struct pf_frent *frent, *next;
 483         uint16_t off, total;
 484
 485         /* Check if we are completely reassembled */
 486         if (TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff)
 487                 return (0);
 488
 489         /* Maximum data we have seen already */
 490         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 491                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 492
 493         /* Check if we have all the data */
 494         off = 0;
 495         for (frent = TAILQ_FIRST(&frag->fr_queue); frent; frent = next) {
 496                 next = TAILQ_NEXT(frent, fr_next);
 497
 498                 off += frent->fe_len;
 499                 if (off < total && (next == NULL || next->fe_off != off)) {
 500                         DPFPRINTF(("missing fragment at %d, next %d, total %d",
 501                             off, next == NULL ? -1 : next->fe_off, total));
 502                         return (0);
 503                 }
 504         }
 505         DPFPRINTF(("%d < %d?", off, total));
 506         if (off < total)
 507                 return (0);
 508         KASSERT(off == total, ("off == total"));
 509
 510         return (1);
 511 }
 512
 513 static struct mbuf *
 514 pf_join_fragment(struct pf_fragment *frag)
 515 {
 516         struct mbuf *m, *m2;
 517         struct pf_frent *frent, *next;
 518
 519         frent = TAILQ_FIRST(&frag->fr_queue);
 520         next = TAILQ_NEXT(frent, fr_next);
 521
 522         m = frent->fe_m;
 523         m_adj(m, (frent->fe_hdrlen + frent->fe_len) - m->m_pkthdr.len);
 524         uma_zfree(V_pf_frent_z, frent);
 525         for (frent = next; frent != NULL; frent = next) {
 526                 next = TAILQ_NEXT(frent, fr_next);
 527
 528                 m2 = frent->fe_m;
 529                 /* Strip off ip header. */
 530                 m_adj(m2, frent->fe_hdrlen);
 531                 /* Strip off any trailing bytes. */
 532                 m_adj(m2, frent->fe_len - m2->m_pkthdr.len);
 533
 534                 uma_zfree(V_pf_frent_z, frent);
 535                 m_cat(m, m2);
 536         }
 537
 538         /* Remove from fragment queue. */
 539         pf_remove_fragment(frag);
 540
 541         return (m);
 542 }
 543
 544 #ifdef INET
 545 static int
 546 pf_reassemble(struct mbuf **m0, struct ip *ip, int dir, u_short *reason)
 547 {
 548         struct mbuf             *m = *m0;
 549         struct pf_frent         *frent;
 550         struct pf_fragment      *frag;
 551         struct pf_fragment_cmp  key;
 552         uint16_t                total, hdrlen;
 553
 554         /* Get an entry for the fragment queue */
 555         if ((frent = pf_create_fragment(reason)) == NULL)
 556                 return (PF_DROP);
 557
 558         frent->fe_m = m;
 559         frent->fe_hdrlen = ip->ip_hl << 2;
 560         frent->fe_extoff = 0;
 561         frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2);
 562         frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3;
 563         frent->fe_mff = ntohs(ip->ip_off) & IP_MF;
 564
 565         pf_ip2key(ip, dir, &key);
 566
 567         if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL)
 568                 return (PF_DROP);
 569
 570         /* The mbuf is part of the fragment entry, no direct free or access */
 571         m = *m0 = NULL;
 572
 573         if (!pf_isfull_fragment(frag))
 574                 return (PF_PASS);  /* drop because *m0 is NULL, no error */
 575
 576         /* We have all the data */
 577         frent = TAILQ_FIRST(&frag->fr_queue);
 578         KASSERT(frent != NULL, ("frent != NULL"));
 579         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 580                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 581         hdrlen = frent->fe_hdrlen;
 582
 583         m = *m0 = pf_join_fragment(frag);
 584         frag = NULL;
 585
 586         if (m->m_flags & M_PKTHDR) {
 587                 int plen = 0;
 588                 for (m = *m0; m; m = m->m_next)
 589                         plen += m->m_len;
 590                 m = *m0;
 591                 m->m_pkthdr.len = plen;
 592         }
 593
 594         ip = mtod(m, struct ip *);
 595         ip->ip_len = htons(hdrlen + total);
 596         ip->ip_off &= ~(IP_MF|IP_OFFMASK);
 597
 598         if (hdrlen + total > IP_MAXPACKET) {
 599                 DPFPRINTF(("drop: too big: %d", total));
 600                 ip->ip_len = 0;
 601                 REASON_SET(reason, PFRES_SHORT);
 602                 /* PF_DROP requires a valid mbuf *m0 in pf_test() */
 603                 return (PF_DROP);
 604         }
 605
 606         DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len)));
 607         return (PF_PASS);
 608 }
 609 #endif  /* INET */
 610
 611 #ifdef INET6
 612 static int
 613 pf_reassemble6(struct mbuf **m0, struct ip6_hdr *ip6, struct ip6_frag *fraghdr,
 614     uint16_t hdrlen, uint16_t extoff, u_short *reason)
 615 {
 616         struct mbuf             *m = *m0;
 617         struct pf_frent         *frent;
 618         struct pf_fragment      *frag;
 619         struct pf_fragment_cmp   key;
 620         struct m_tag            *mtag;
 621         struct pf_fragment_tag  *ftag;
 622         int                      off;
 623         uint32_t                 frag_id;
 624         uint16_t                 total, maxlen;
 625         uint8_t                  proto;
 626
 627         PF_FRAG_LOCK();
 628
 629         /* Get an entry for the fragment queue. */
 630         if ((frent = pf_create_fragment(reason)) == NULL) {
 631                 PF_FRAG_UNLOCK();
 632                 return (PF_DROP);
 633         }
 634
 635         frent->fe_m = m;
 636         frent->fe_hdrlen = hdrlen;
 637         frent->fe_extoff = extoff;
 638         frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen;
 639         frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK);
 640         frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG;
 641
 642         key.frc_src.v6 = ip6->ip6_src;
 643         key.frc_dst.v6 = ip6->ip6_dst;
 644         key.frc_af = AF_INET6;
 645         /* Only the first fragment's protocol is relevant. */
 646         key.frc_proto = 0;
 647         key.frc_id = fraghdr->ip6f_ident;
 648
 649         if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) {
 650                 PF_FRAG_UNLOCK();
 651                 return (PF_DROP);
 652         }
 653
 654         /* The mbuf is part of the fragment entry, no direct free or access. */
 655         m = *m0 = NULL;
 656
 657         if (!pf_isfull_fragment(frag)) {
 658                 PF_FRAG_UNLOCK();
 659                 return (PF_PASS);  /* Drop because *m0 is NULL, no error. */
 660         }
 661
 662         /* We have all the data. */
 663         extoff = frent->fe_extoff;
 664         maxlen = frag->fr_maxlen;
 665         frag_id = frag->fr_id;
 666         frent = TAILQ_FIRST(&frag->fr_queue);
 667         KASSERT(frent != NULL, ("frent != NULL"));
 668         total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
 669                 TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
 670         hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag);
 671
 672         m = *m0 = pf_join_fragment(frag);
 673         frag = NULL;
 674
 675         PF_FRAG_UNLOCK();
 676
 677         /* Take protocol from first fragment header. */
 678         m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off);
 679         KASSERT(m, ("%s: short mbuf chain", __func__));
 680         proto = *(mtod(m, caddr_t) + off);
 681         m = *m0;
 682
 683         /* Delete frag6 header */
 684         if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0)
 685                 goto fail;
 686
 687         if (m->m_flags & M_PKTHDR) {
 688                 int plen = 0;
 689                 for (m = *m0; m; m = m->m_next)
 690                         plen += m->m_len;
 691                 m = *m0;
 692                 m->m_pkthdr.len = plen;
 693         }
 694
 695         if ((mtag = m_tag_get(PF_REASSEMBLED, sizeof(struct pf_fragment_tag),
 696             M_NOWAIT)) == NULL)
 697                 goto fail;
 698         ftag = (struct pf_fragment_tag *)(mtag + 1);
 699         ftag->ft_hdrlen = hdrlen;
 700         ftag->ft_extoff = extoff;
 701         ftag->ft_maxlen = maxlen;
 702         ftag->ft_id = frag_id;
 703         m_tag_prepend(m, mtag);
 704
 705         ip6 = mtod(m, struct ip6_hdr *);
 706         ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total);
 707         if (extoff) {
 708                 /* Write protocol into next field of last extension header. */
 709                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
 710                     &off);
 711                 KASSERT(m, ("%s: short mbuf chain", __func__));
 712                 *(mtod(m, char *) + off) = proto;
 713                 m = *m0;
 714         } else
 715                 ip6->ip6_nxt = proto;
 716
 717         if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) {
 718                 DPFPRINTF(("drop: too big: %d", total));
 719                 ip6->ip6_plen = 0;
 720                 REASON_SET(reason, PFRES_SHORT);
 721                 /* PF_DROP requires a valid mbuf *m0 in pf_test6(). */
 722                 return (PF_DROP);
 723         }
 724
 725         DPFPRINTF(("complete: %p(%d)", m, ntohs(ip6->ip6_plen)));
 726         return (PF_PASS);
 727
 728 fail:
 729         REASON_SET(reason, PFRES_MEMORY);
 730         /* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */
 731         return (PF_DROP);
 732 }
 733 #endif  /* INET6 */
 734
 735 #ifdef INET6
 736 int
 737 pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag)
 738 {
 739         struct mbuf             *m = *m0, *t;
 740         struct pf_fragment_tag  *ftag = (struct pf_fragment_tag *)(mtag + 1);
 741         struct pf_pdesc          pd;
 742         uint32_t                 frag_id;
 743         uint16_t                 hdrlen, extoff, maxlen;
 744         uint8_t                  proto;
 745         int                      error, action;
 746
 747         hdrlen = ftag->ft_hdrlen;
 748         extoff = ftag->ft_extoff;
 749         maxlen = ftag->ft_maxlen;
 750         frag_id = ftag->ft_id;
 751         m_tag_delete(m, mtag);
 752         mtag = NULL;
 753         ftag = NULL;
 754
 755         if (extoff) {
 756                 int off;
 757
 758                 /* Use protocol from next field of last extension header */
 759                 m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
 760                     &off);
 761                 KASSERT((m != NULL), ("pf_refragment6: short mbuf chain"));
 762                 proto = *(mtod(m, caddr_t) + off);
 763                 *(mtod(m, char *) + off) = IPPROTO_FRAGMENT;
 764                 m = *m0;
 765         } else {
 766                 struct ip6_hdr *hdr;
 767
 768                 hdr = mtod(m, struct ip6_hdr *);
 769                 proto = hdr->ip6_nxt;
 770                 hdr->ip6_nxt = IPPROTO_FRAGMENT;
 771         }
 772
 773         /* The MTU must be a multiple of 8 bytes, or we risk doing the
 774          * fragmentation wrong. */
 775         maxlen = maxlen & ~7;
 776
 777         /*
 778          * Maxlen may be less than 8 if there was only a single
 779          * fragment.  As it was fragmented before, add a fragment
 780          * header also for a single fragment.  If total or maxlen
 781          * is less than 8, ip6_fragment() will return EMSGSIZE and
 782          * we drop the packet.
 783          */
 784         error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id);
 785         m = (*m0)->m_nextpkt;
 786         (*m0)->m_nextpkt = NULL;
 787         if (error == 0) {
 788                 /* The first mbuf contains the unfragmented packet. */
 789                 m_freem(*m0);
 790                 *m0 = NULL;
 791                 action = PF_PASS;
 792         } else {
 793                 /* Drop expects an mbuf to free. */
 794                 DPFPRINTF(("refragment error %d", error));
 795                 action = PF_DROP;
 796         }
 797         for (t = m; m; m = t) {
 798                 t = m->m_nextpkt;
 799                 m->m_nextpkt = NULL;
 800                 m->m_flags |= M_SKIP_FIREWALL;
 801                 memset(&pd, 0, sizeof(pd));
 802                 pd.pf_mtag = pf_find_mtag(m);
 803                 if (error == 0)
 804                         ip6_forward(m, 0);
 805                 else
 806                         m_freem(m);
 807         }
 808
 809         return (action);
 810 }
 811 #endif /* INET6 */
 812
 813 #ifdef INET
 814 int
 815 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason,
 816     struct pf_pdesc *pd)
 817 {
 818         struct mbuf             *m = *m0;
 819         struct pf_rule          *r;
 820         struct ip               *h = mtod(m, struct ip *);
 821         int                      mff = (ntohs(h->ip_off) & IP_MF);
 822         int                      hlen = h->ip_hl << 2;
 823         u_int16_t                fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
 824         u_int16_t                max;
 825         int                      ip_len;
 826         int                      ip_off;
 827         int                      tag = -1;
 828         int                      verdict;
 829
 830         PF_RULES_RASSERT();
 831
 832         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
 833         while (r != NULL) {
 834                 r->evaluations++;
 835                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
 836                         r = r->skip[PF_SKIP_IFP].ptr;
 837                 else if (r->direction && r->direction != dir)
 838                         r = r->skip[PF_SKIP_DIR].ptr;
 839                 else if (r->af && r->af != AF_INET)
 840                         r = r->skip[PF_SKIP_AF].ptr;
 841                 else if (r->proto && r->proto != h->ip_p)
 842                         r = r->skip[PF_SKIP_PROTO].ptr;
 843                 else if (PF_MISMATCHAW(&r->src.addr,
 844                     (struct pf_addr *)&h->ip_src.s_addr, AF_INET,
 845                     r->src.neg, kif, M_GETFIB(m)))
 846                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
 847                 else if (PF_MISMATCHAW(&r->dst.addr,
 848                     (struct pf_addr *)&h->ip_dst.s_addr, AF_INET,
 849                     r->dst.neg, NULL, M_GETFIB(m)))
 850                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
 851                 else if (r->match_tag && !pf_match_tag(m, r, &tag,
 852                     pd->pf_mtag ? pd->pf_mtag->tag : 0))
 853                         r = TAILQ_NEXT(r, entries);
 854                 else
 855                         break;
 856         }
 857
 858         if (r == NULL || r->action == PF_NOSCRUB)
 859                 return (PF_PASS);
 860         else {
 861                 r->packets[dir == PF_OUT]++;
 862                 r->bytes[dir == PF_OUT] += pd->tot_len;
 863         }
 864
 865         /* Check for illegal packets */
 866         if (hlen < (int)sizeof(struct ip)) {
 867                 REASON_SET(reason, PFRES_NORM);
 868                 goto drop;
 869         }
 870
 871         if (hlen > ntohs(h->ip_len)) {
 872                 REASON_SET(reason, PFRES_NORM);
 873                 goto drop;
 874         }
 875
 876         /* Clear IP_DF if the rule uses the no-df option */
 877         if (r->rule_flag & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
 878                 u_int16_t ip_off = h->ip_off;
 879
 880                 h->ip_off &= htons(~IP_DF);
 881                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
 882         }
 883
 884         /* We will need other tests here */
 885         if (!fragoff && !mff)
 886                 goto no_fragment;
 887
 888         /* We're dealing with a fragment now. Don't allow fragments
 889          * with IP_DF to enter the cache. If the flag was cleared by
 890          * no-df above, fine. Otherwise drop it.
 891          */
 892         if (h->ip_off & htons(IP_DF)) {
 893                 DPFPRINTF(("IP_DF\n"));
 894                 goto bad;
 895         }
 896
 897         ip_len = ntohs(h->ip_len) - hlen;
 898         ip_off = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
 899
 900         /* All fragments are 8 byte aligned */
 901         if (mff && (ip_len & 0x7)) {
 902                 DPFPRINTF(("mff and %d\n", ip_len));
 903                 goto bad;
 904         }
 905
 906         /* Respect maximum length */
 907         if (fragoff + ip_len > IP_MAXPACKET) {
 908                 DPFPRINTF(("max packet %d\n", fragoff + ip_len));
 909                 goto bad;
 910         }
 911         max = fragoff + ip_len;
 912
 913         /* Fully buffer all of the fragments
 914          * Might return a completely reassembled mbuf, or NULL */
 915         PF_FRAG_LOCK();
 916         DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
 917         verdict = pf_reassemble(m0, h, dir, reason);
 918         PF_FRAG_UNLOCK();
 919
 920         if (verdict != PF_PASS)
 921                 return (PF_DROP);
 922
 923         m = *m0;
 924         if (m == NULL)
 925                 return (PF_DROP);
 926
 927         h = mtod(m, struct ip *);
 928
 929  no_fragment:
 930         /* At this point, only IP_DF is allowed in ip_off */
 931         if (h->ip_off & ~htons(IP_DF)) {
 932                 u_int16_t ip_off = h->ip_off;
 933
 934                 h->ip_off &= htons(IP_DF);
 935                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
 936         }
 937
 938         pf_scrub_ip(&m, r->rule_flag, r->min_ttl, r->set_tos);
 939
 940         return (PF_PASS);
 941
 942  bad:
 943         DPFPRINTF(("dropping bad fragment\n"));
 944         REASON_SET(reason, PFRES_FRAG);
 945  drop:
 946         if (r != NULL && r->log)
 947                 PFLOG_PACKET(kif, m, AF_INET, dir, *reason, r, NULL, NULL, pd,
 948                     1);
 949
 950         return (PF_DROP);
 951 }
 952 #endif
 953
 954 #ifdef INET6
 955 int
 956 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif,
 957     u_short *reason, struct pf_pdesc *pd)
 958 {
 959         struct mbuf             *m = *m0;
 960         struct pf_rule          *r;
 961         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
 962         int                      extoff;
 963         int                      off;
 964         struct ip6_ext           ext;
 965         struct ip6_opt           opt;
 966         struct ip6_opt_jumbo     jumbo;
 967         struct ip6_frag          frag;
 968         u_int32_t                jumbolen = 0, plen;
 969         int                      optend;
 970         int                      ooff;
 971         u_int8_t                 proto;
 972         int                      terminal;
 973
 974         PF_RULES_RASSERT();
 975
 976         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
 977         while (r != NULL) {
 978                 r->evaluations++;
 979                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
 980                         r = r->skip[PF_SKIP_IFP].ptr;
 981                 else if (r->direction && r->direction != dir)
 982                         r = r->skip[PF_SKIP_DIR].ptr;
 983                 else if (r->af && r->af != AF_INET6)
 984                         r = r->skip[PF_SKIP_AF].ptr;
 985 #if 0 /* header chain! */
 986                 else if (r->proto && r->proto != h->ip6_nxt)
 987                         r = r->skip[PF_SKIP_PROTO].ptr;
 988 #endif
 989                 else if (PF_MISMATCHAW(&r->src.addr,
 990                     (struct pf_addr *)&h->ip6_src, AF_INET6,
 991                     r->src.neg, kif, M_GETFIB(m)))
 992                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
 993                 else if (PF_MISMATCHAW(&r->dst.addr,
 994                     (struct pf_addr *)&h->ip6_dst, AF_INET6,
 995                     r->dst.neg, NULL, M_GETFIB(m)))
 996                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
 997                 else
 998                         break;
 999         }
1000
1001         if (r == NULL || r->action == PF_NOSCRUB)
1002                 return (PF_PASS);
1003         else {
1004                 r->packets[dir == PF_OUT]++;
1005                 r->bytes[dir == PF_OUT] += pd->tot_len;
1006         }
1007
1008         /* Check for illegal packets */
1009         if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len)
1010                 goto drop;
1011
1012         extoff = 0;
1013         off = sizeof(struct ip6_hdr);
1014         proto = h->ip6_nxt;
1015         terminal = 0;
1016         do {
1017                 switch (proto) {
1018                 case IPPROTO_FRAGMENT:
1019                         goto fragment;
1020                         break;
1021                 case IPPROTO_AH:
1022                 case IPPROTO_ROUTING:
1023                 case IPPROTO_DSTOPTS:
1024                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1025                             NULL, AF_INET6))
1026                                 goto shortpkt;
1027                         extoff = off;
1028                         if (proto == IPPROTO_AH)
1029                                 off += (ext.ip6e_len + 2) * 4;
1030                         else
1031                                 off += (ext.ip6e_len + 1) * 8;
1032                         proto = ext.ip6e_nxt;
1033                         break;
1034                 case IPPROTO_HOPOPTS:
1035                         if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1036                             NULL, AF_INET6))
1037                                 goto shortpkt;
1038                         extoff = off;
1039                         optend = off + (ext.ip6e_len + 1) * 8;
1040                         ooff = off + sizeof(ext);
1041                         do {
1042                                 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type,
1043                                     sizeof(opt.ip6o_type), NULL, NULL,
1044                                     AF_INET6))
1045                                         goto shortpkt;
1046                                 if (opt.ip6o_type == IP6OPT_PAD1) {
1047                                         ooff++;
1048                                         continue;
1049                                 }
1050                                 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt),
1051                                     NULL, NULL, AF_INET6))
1052                                         goto shortpkt;
1053                                 if (ooff + sizeof(opt) + opt.ip6o_len > optend)
1054                                         goto drop;
1055                                 switch (opt.ip6o_type) {
1056                                 case IP6OPT_JUMBO:
1057                                         if (h->ip6_plen != 0)
1058                                                 goto drop;
1059                                         if (!pf_pull_hdr(m, ooff, &jumbo,
1060                                             sizeof(jumbo), NULL, NULL,
1061                                             AF_INET6))
1062                                                 goto shortpkt;
1063                                         memcpy(&jumbolen, jumbo.ip6oj_jumbo_len,
1064                                             sizeof(jumbolen));
1065                                         jumbolen = ntohl(jumbolen);
1066                                         if (jumbolen <= IPV6_MAXPACKET)
1067                                                 goto drop;
1068                                         if (sizeof(struct ip6_hdr) + jumbolen !=
1069                                             m->m_pkthdr.len)
1070                                                 goto drop;
1071                                         break;
1072                                 default:
1073                                         break;
1074                                 }
1075                                 ooff += sizeof(opt) + opt.ip6o_len;
1076                         } while (ooff < optend);
1077
1078                         off = optend;
1079                         proto = ext.ip6e_nxt;
1080                         break;
1081                 default:
1082                         terminal = 1;
1083                         break;
1084                 }
1085         } while (!terminal);
1086
1087         /* jumbo payload option must be present, or plen > 0 */
1088         if (ntohs(h->ip6_plen) == 0)
1089                 plen = jumbolen;
1090         else
1091                 plen = ntohs(h->ip6_plen);
1092         if (plen == 0)
1093                 goto drop;
1094         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1095                 goto shortpkt;
1096
1097         pf_scrub_ip6(&m, r->min_ttl);
1098
1099         return (PF_PASS);
1100
1101  fragment:
1102         /* Jumbo payload packets cannot be fragmented. */
1103         plen = ntohs(h->ip6_plen);
1104         if (plen == 0 || jumbolen)
1105                 goto drop;
1106         if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1107                 goto shortpkt;
1108
1109         if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6))
1110                 goto shortpkt;
1111
1112         /* Offset now points to data portion. */
1113         off += sizeof(frag);
1114
1115         /* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */
1116         if (pf_reassemble6(m0, h, &frag, off, extoff, reason) != PF_PASS)
1117                 return (PF_DROP);
1118         m = *m0;
1119         if (m == NULL)
1120                 return (PF_DROP);
1121
1122         pd->flags |= PFDESC_IP_REAS;
1123         return (PF_PASS);
1124
1125  shortpkt:
1126         REASON_SET(reason, PFRES_SHORT);
1127         if (r != NULL && r->log)
1128                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1129                     1);
1130         return (PF_DROP);
1131
1132  drop:
1133         REASON_SET(reason, PFRES_NORM);
1134         if (r != NULL && r->log)
1135                 PFLOG_PACKET(kif, m, AF_INET6, dir, *reason, r, NULL, NULL, pd,
1136                     1);
1137         return (PF_DROP);
1138 }
1139 #endif /* INET6 */
1140
1141 int
1142 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m, int ipoff,
1143     int off, void *h, struct pf_pdesc *pd)
1144 {
1145         struct pf_rule  *r, *rm = NULL;
1146         struct tcphdr   *th = pd->hdr.tcp;
1147         int              rewrite = 0;
1148         u_short          reason;
1149         u_int8_t         flags;
1150         sa_family_t      af = pd->af;
1151
1152         PF_RULES_RASSERT();
1153
1154         r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1155         while (r != NULL) {
1156                 r->evaluations++;
1157                 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1158                         r = r->skip[PF_SKIP_IFP].ptr;
1159                 else if (r->direction && r->direction != dir)
1160                         r = r->skip[PF_SKIP_DIR].ptr;
1161                 else if (r->af && r->af != af)
1162                         r = r->skip[PF_SKIP_AF].ptr;
1163                 else if (r->proto && r->proto != pd->proto)
1164                         r = r->skip[PF_SKIP_PROTO].ptr;
1165                 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af,
1166                     r->src.neg, kif, M_GETFIB(m)))
1167                         r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1168                 else if (r->src.port_op && !pf_match_port(r->src.port_op,
1169                             r->src.port[0], r->src.port[1], th->th_sport))
1170                         r = r->skip[PF_SKIP_SRC_PORT].ptr;
1171                 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af,
1172                     r->dst.neg, NULL, M_GETFIB(m)))
1173                         r = r->skip[PF_SKIP_DST_ADDR].ptr;
1174                 else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
1175                             r->dst.port[0], r->dst.port[1], th->th_dport))
1176                         r = r->skip[PF_SKIP_DST_PORT].ptr;
1177                 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match(
1178                             pf_osfp_fingerprint(pd, m, off, th),
1179                             r->os_fingerprint))
1180                         r = TAILQ_NEXT(r, entries);
1181                 else {
1182                         rm = r;
1183                         break;
1184                 }
1185         }
1186
1187         if (rm == NULL || rm->action == PF_NOSCRUB)
1188                 return (PF_PASS);
1189         else {
1190                 r->packets[dir == PF_OUT]++;
1191                 r->bytes[dir == PF_OUT] += pd->tot_len;
1192         }
1193
1194         if (rm->rule_flag & PFRULE_REASSEMBLE_TCP)
1195                 pd->flags |= PFDESC_TCP_NORM;
1196
1197         flags = th->th_flags;
1198         if (flags & TH_SYN) {
1199                 /* Illegal packet */
1200                 if (flags & TH_RST)
1201                         goto tcp_drop;
1202
1203                 if (flags & TH_FIN)
1204                         goto tcp_drop;
1205         } else {
1206                 /* Illegal packet */
1207                 if (!(flags & (TH_ACK|TH_RST)))
1208                         goto tcp_drop;
1209         }
1210
1211         if (!(flags & TH_ACK)) {
1212                 /* These flags are only valid if ACK is set */
1213                 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG))
1214                         goto tcp_drop;
1215         }
1216
1217         /* Check for illegal header length */
1218         if (th->th_off < (sizeof(struct tcphdr) >> 2))
1219                 goto tcp_drop;
1220
1221         /* If flags changed, or reserved data set, then adjust */
1222         if (flags != th->th_flags || th->th_x2 != 0) {
1223                 u_int16_t       ov, nv;
1224
1225                 ov = *(u_int16_t *)(&th->th_ack + 1);
1226                 th->th_flags = flags;
1227                 th->th_x2 = 0;
1228                 nv = *(u_int16_t *)(&th->th_ack + 1);
1229
1230                 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, ov, nv, 0);
1231                 rewrite = 1;
1232         }
1233
1234         /* Remove urgent pointer, if TH_URG is not set */
1235         if (!(flags & TH_URG) && th->th_urp) {
1236                 th->th_sum = pf_proto_cksum_fixup(m, th->th_sum, th->th_urp,
1237                     0, 0);
1238                 th->th_urp = 0;
1239                 rewrite = 1;
1240         }
1241
1242         /* Process options */
1243         if (r->max_mss && pf_normalize_tcpopt(r, m, th, off, pd->af))
1244                 rewrite = 1;
1245
1246         /* copy back packet headers if we sanitized */
1247         if (rewrite)
1248                 m_copyback(m, off, sizeof(*th), (caddr_t)th);
1249
1250         return (PF_PASS);
1251
1252  tcp_drop:
1253         REASON_SET(&reason, PFRES_NORM);
1254         if (rm != NULL && r->log)
1255                 PFLOG_PACKET(kif, m, AF_INET, dir, reason, r, NULL, NULL, pd,
1256                     1);
1257         return (PF_DROP);
1258 }
1259
1260 int
1261 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd,
1262     struct tcphdr *th, struct pf_state_peer *src, struct pf_state_peer *dst)
1263 {
1264         u_int32_t tsval, tsecr;
1265         u_int8_t hdr[60];
1266         u_int8_t *opt;
1267
1268         KASSERT((src->scrub == NULL),
1269             ("pf_normalize_tcp_init: src->scrub != NULL"));
1270
1271         src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT);
1272         if (src->scrub == NULL)
1273                 return (1);
1274
1275         switch (pd->af) {
1276 #ifdef INET
1277         case AF_INET: {
1278                 struct ip *h = mtod(m, struct ip *);
1279                 src->scrub->pfss_ttl = h->ip_ttl;
1280                 break;
1281         }
1282 #endif /* INET */
1283 #ifdef INET6
1284         case AF_INET6: {
1285                 struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1286                 src->scrub->pfss_ttl = h->ip6_hlim;
1287                 break;
1288         }
1289 #endif /* INET6 */
1290         }
1291
1292
1293         /*
1294          * All normalizations below are only begun if we see the start of
1295          * the connections.  They must all set an enabled bit in pfss_flags
1296          */
1297         if ((th->th_flags & TH_SYN) == 0)
1298                 return (0);
1299
1300
1301         if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub &&
1302             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1303                 /* Diddle with TCP options */
1304                 int hlen;
1305                 opt = hdr + sizeof(struct tcphdr);
1306                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1307                 while (hlen >= TCPOLEN_TIMESTAMP) {
1308                         switch (*opt) {
1309                         case TCPOPT_EOL:        /* FALLTHROUGH */
1310                         case TCPOPT_NOP:
1311                                 opt++;
1312                                 hlen--;
1313                                 break;
1314                         case TCPOPT_TIMESTAMP:
1315                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1316                                         src->scrub->pfss_flags |=
1317                                             PFSS_TIMESTAMP;
1318                                         src->scrub->pfss_ts_mod =
1319                                             htonl(arc4random());
1320
1321                                         /* note PFSS_PAWS not set yet */
1322                                         memcpy(&tsval, &opt[2],
1323                                             sizeof(u_int32_t));
1324                                         memcpy(&tsecr, &opt[6],
1325                                             sizeof(u_int32_t));
1326                                         src->scrub->pfss_tsval0 = ntohl(tsval);
1327                                         src->scrub->pfss_tsval = ntohl(tsval);
1328                                         src->scrub->pfss_tsecr = ntohl(tsecr);
1329                                         getmicrouptime(&src->scrub->pfss_last);
1330                                 }
1331                                 /* FALLTHROUGH */
1332                         default:
1333                                 hlen -= MAX(opt[1], 2);
1334                                 opt += MAX(opt[1], 2);
1335                                 break;
1336                         }
1337                 }
1338         }
1339
1340         return (0);
1341 }
1342
1343 void
1344 pf_normalize_tcp_cleanup(struct pf_state *state)
1345 {
1346         if (state->src.scrub)
1347                 uma_zfree(V_pf_state_scrub_z, state->src.scrub);
1348         if (state->dst.scrub)
1349                 uma_zfree(V_pf_state_scrub_z, state->dst.scrub);
1350
1351         /* Someday... flush the TCP segment reassembly descriptors. */
1352 }
1353
1354 int
1355 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd,
1356     u_short *reason, struct tcphdr *th, struct pf_state *state,
1357     struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback)
1358 {
1359         struct timeval uptime;
1360         u_int32_t tsval, tsecr;
1361         u_int tsval_from_last;
1362         u_int8_t hdr[60];
1363         u_int8_t *opt;
1364         int copyback = 0;
1365         int got_ts = 0;
1366
1367         KASSERT((src->scrub || dst->scrub),
1368             ("%s: src->scrub && dst->scrub!", __func__));
1369
1370         /*
1371          * Enforce the minimum TTL seen for this connection.  Negate a common
1372          * technique to evade an intrusion detection system and confuse
1373          * firewall state code.
1374          */
1375         switch (pd->af) {
1376 #ifdef INET
1377         case AF_INET: {
1378                 if (src->scrub) {
1379                         struct ip *h = mtod(m, struct ip *);
1380                         if (h->ip_ttl > src->scrub->pfss_ttl)
1381                                 src->scrub->pfss_ttl = h->ip_ttl;
1382                         h->ip_ttl = src->scrub->pfss_ttl;
1383                 }
1384                 break;
1385         }
1386 #endif /* INET */
1387 #ifdef INET6
1388         case AF_INET6: {
1389                 if (src->scrub) {
1390                         struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1391                         if (h->ip6_hlim > src->scrub->pfss_ttl)
1392                                 src->scrub->pfss_ttl = h->ip6_hlim;
1393                         h->ip6_hlim = src->scrub->pfss_ttl;
1394                 }
1395                 break;
1396         }
1397 #endif /* INET6 */
1398         }
1399
1400         if (th->th_off > (sizeof(struct tcphdr) >> 2) &&
1401             ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) ||
1402             (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) &&
1403             pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1404                 /* Diddle with TCP options */
1405                 int hlen;
1406                 opt = hdr + sizeof(struct tcphdr);
1407                 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1408                 while (hlen >= TCPOLEN_TIMESTAMP) {
1409                         switch (*opt) {
1410                         case TCPOPT_EOL:        /* FALLTHROUGH */
1411                         case TCPOPT_NOP:
1412                                 opt++;
1413                                 hlen--;
1414                                 break;
1415                         case TCPOPT_TIMESTAMP:
1416                                 /* Modulate the timestamps.  Can be used for
1417                                  * NAT detection, OS uptime determination or
1418                                  * reboot detection.
1419                                  */
1420
1421                                 if (got_ts) {
1422                                         /* Huh?  Multiple timestamps!? */
1423                                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1424                                                 DPFPRINTF(("multiple TS??"));
1425                                                 pf_print_state(state);
1426                                                 printf("\n");
1427                                         }
1428                                         REASON_SET(reason, PFRES_TS);
1429                                         return (PF_DROP);
1430                                 }
1431                                 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1432                                         memcpy(&tsval, &opt[2],
1433                                             sizeof(u_int32_t));
1434                                         if (tsval && src->scrub &&
1435                                             (src->scrub->pfss_flags &
1436                                             PFSS_TIMESTAMP)) {
1437                                                 tsval = ntohl(tsval);
1438                                                 pf_change_proto_a(m, &opt[2],
1439                                                     &th->th_sum,
1440                                                     htonl(tsval +
1441                                                     src->scrub->pfss_ts_mod),
1442                                                     0);
1443                                                 copyback = 1;
1444                                         }
1445
1446                                         /* Modulate TS reply iff valid (!0) */
1447                                         memcpy(&tsecr, &opt[6],
1448                                             sizeof(u_int32_t));
1449                                         if (tsecr && dst->scrub &&
1450                                             (dst->scrub->pfss_flags &
1451                                             PFSS_TIMESTAMP)) {
1452                                                 tsecr = ntohl(tsecr)
1453                                                     - dst->scrub->pfss_ts_mod;
1454                                                 pf_change_proto_a(m, &opt[6],
1455                                                     &th->th_sum, htonl(tsecr),
1456                                                     0);
1457                                                 copyback = 1;
1458                                         }
1459                                         got_ts = 1;
1460                                 }
1461                                 /* FALLTHROUGH */
1462                         default:
1463                                 hlen -= MAX(opt[1], 2);
1464                                 opt += MAX(opt[1], 2);
1465                                 break;
1466                         }
1467                 }
1468                 if (copyback) {
1469                         /* Copyback the options, caller copys back header */
1470                         *writeback = 1;
1471                         m_copyback(m, off + sizeof(struct tcphdr),
1472                             (th->th_off << 2) - sizeof(struct tcphdr), hdr +
1473                             sizeof(struct tcphdr));
1474                 }
1475         }
1476
1477
1478         /*
1479          * Must invalidate PAWS checks on connections idle for too long.
1480          * The fastest allowed timestamp clock is 1ms.  That turns out to
1481          * be about 24 days before it wraps.  XXX Right now our lowerbound
1482          * TS echo check only works for the first 12 days of a connection
1483          * when the TS has exhausted half its 32bit space
1484          */
1485 #define TS_MAX_IDLE     (24*24*60*60)
1486 #define TS_MAX_CONN     (12*24*60*60)   /* XXX remove when better tsecr check */
1487
1488         getmicrouptime(&uptime);
1489         if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) &&
1490             (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE ||
1491             time_uptime - state->creation > TS_MAX_CONN))  {
1492                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1493                         DPFPRINTF(("src idled out of PAWS\n"));
1494                         pf_print_state(state);
1495                         printf("\n");
1496                 }
1497                 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS)
1498                     | PFSS_PAWS_IDLED;
1499         }
1500         if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) &&
1501             uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) {
1502                 if (V_pf_status.debug >= PF_DEBUG_MISC) {
1503                         DPFPRINTF(("dst idled out of PAWS\n"));
1504                         pf_print_state(state);
1505                         printf("\n");
1506                 }
1507                 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS)
1508                     | PFSS_PAWS_IDLED;
1509         }
1510
1511         if (got_ts && src->scrub && dst->scrub &&
1512             (src->scrub->pfss_flags & PFSS_PAWS) &&
1513             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1514                 /* Validate that the timestamps are "in-window".
1515                  * RFC1323 describes TCP Timestamp options that allow
1516                  * measurement of RTT (round trip time) and PAWS
1517                  * (protection against wrapped sequence numbers).  PAWS
1518                  * gives us a set of rules for rejecting packets on
1519                  * long fat pipes (packets that were somehow delayed
1520                  * in transit longer than the time it took to send the
1521                  * full TCP sequence space of 4Gb).  We can use these
1522                  * rules and infer a few others that will let us treat
1523                  * the 32bit timestamp and the 32bit echoed timestamp
1524                  * as sequence numbers to prevent a blind attacker from
1525                  * inserting packets into a connection.
1526                  *
1527                  * RFC1323 tells us:
1528                  *  - The timestamp on this packet must be greater than
1529                  *    or equal to the last value echoed by the other
1530                  *    endpoint.  The RFC says those will be discarded
1531                  *    since it is a dup that has already been acked.
1532                  *    This gives us a lowerbound on the timestamp.
1533                  *        timestamp >= other last echoed timestamp
1534                  *  - The timestamp will be less than or equal to
1535                  *    the last timestamp plus the time between the
1536                  *    last packet and now.  The RFC defines the max
1537                  *    clock rate as 1ms.  We will allow clocks to be
1538                  *    up to 10% fast and will allow a total difference
1539                  *    or 30 seconds due to a route change.  And this
1540                  *    gives us an upperbound on the timestamp.
1541                  *        timestamp <= last timestamp + max ticks
1542                  *    We have to be careful here.  Windows will send an
1543                  *    initial timestamp of zero and then initialize it
1544                  *    to a random value after the 3whs; presumably to
1545                  *    avoid a DoS by having to call an expensive RNG
1546                  *    during a SYN flood.  Proof MS has at least one
1547                  *    good security geek.
1548                  *
1549                  *  - The TCP timestamp option must also echo the other
1550                  *    endpoints timestamp.  The timestamp echoed is the
1551                  *    one carried on the earliest unacknowledged segment
1552                  *    on the left edge of the sequence window.  The RFC
1553                  *    states that the host will reject any echoed
1554                  *    timestamps that were larger than any ever sent.
1555                  *    This gives us an upperbound on the TS echo.
1556                  *        tescr <= largest_tsval
1557                  *  - The lowerbound on the TS echo is a little more
1558                  *    tricky to determine.  The other endpoint's echoed
1559                  *    values will not decrease.  But there may be
1560                  *    network conditions that re-order packets and
1561                  *    cause our view of them to decrease.  For now the
1562                  *    only lowerbound we can safely determine is that
1563                  *    the TS echo will never be less than the original
1564                  *    TS.  XXX There is probably a better lowerbound.
1565                  *    Remove TS_MAX_CONN with better lowerbound check.
1566                  *        tescr >= other original TS
1567                  *
1568                  * It is also important to note that the fastest
1569                  * timestamp clock of 1ms will wrap its 32bit space in
1570                  * 24 days.  So we just disable TS checking after 24
1571                  * days of idle time.  We actually must use a 12d
1572                  * connection limit until we can come up with a better
1573                  * lowerbound to the TS echo check.
1574                  */
1575                 struct timeval delta_ts;
1576                 int ts_fudge;
1577
1578
1579                 /*
1580                  * PFTM_TS_DIFF is how many seconds of leeway to allow
1581                  * a host's timestamp.  This can happen if the previous
1582                  * packet got delayed in transit for much longer than
1583                  * this packet.
1584                  */
1585                 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0)
1586                         ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF];
1587
1588                 /* Calculate max ticks since the last timestamp */
1589 #define TS_MAXFREQ      1100            /* RFC max TS freq of 1Khz + 10% skew */
1590 #define TS_MICROSECS    1000000         /* microseconds per second */
1591                 delta_ts = uptime;
1592                 timevalsub(&delta_ts, &src->scrub->pfss_last);
1593                 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ;
1594                 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ);
1595
1596                 if ((src->state >= TCPS_ESTABLISHED &&
1597                     dst->state >= TCPS_ESTABLISHED) &&
1598                     (SEQ_LT(tsval, dst->scrub->pfss_tsecr) ||
1599                     SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) ||
1600                     (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) ||
1601                     SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) {
1602                         /* Bad RFC1323 implementation or an insertion attack.
1603                          *
1604                          * - Solaris 2.6 and 2.7 are known to send another ACK
1605                          *   after the FIN,FIN|ACK,ACK closing that carries
1606                          *   an old timestamp.
1607                          */
1608
1609                         DPFPRINTF(("Timestamp failed %c%c%c%c\n",
1610                             SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ',
1611                             SEQ_GT(tsval, src->scrub->pfss_tsval +
1612                             tsval_from_last) ? '1' : ' ',
1613                             SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ',
1614                             SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' '));
1615                         DPFPRINTF((" tsval: %u  tsecr: %u  +ticks: %u  "
1616                             "idle: %jus %lums\n",
1617                             tsval, tsecr, tsval_from_last,
1618                             (uintmax_t)delta_ts.tv_sec,
1619                             delta_ts.tv_usec / 1000));
1620                         DPFPRINTF((" src->tsval: %u  tsecr: %u\n",
1621                             src->scrub->pfss_tsval, src->scrub->pfss_tsecr));
1622                         DPFPRINTF((" dst->tsval: %u  tsecr: %u  tsval0: %u"
1623                             "\n", dst->scrub->pfss_tsval,
1624                             dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0));
1625                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1626                                 pf_print_state(state);
1627                                 pf_print_flags(th->th_flags);
1628                                 printf("\n");
1629                         }
1630                         REASON_SET(reason, PFRES_TS);
1631                         return (PF_DROP);
1632                 }
1633
1634                 /* XXX I'd really like to require tsecr but it's optional */
1635
1636         } else if (!got_ts && (th->th_flags & TH_RST) == 0 &&
1637             ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED)
1638             || pd->p_len > 0 || (th->th_flags & TH_SYN)) &&
1639             src->scrub && dst->scrub &&
1640             (src->scrub->pfss_flags & PFSS_PAWS) &&
1641             (dst->scrub->pfss_flags & PFSS_PAWS)) {
1642                 /* Didn't send a timestamp.  Timestamps aren't really useful
1643                  * when:
1644                  *  - connection opening or closing (often not even sent).
1645                  *    but we must not let an attacker to put a FIN on a
1646                  *    data packet to sneak it through our ESTABLISHED check.
1647                  *  - on a TCP reset.  RFC suggests not even looking at TS.
1648                  *  - on an empty ACK.  The TS will not be echoed so it will
1649                  *    probably not help keep the RTT calculation in sync and
1650                  *    there isn't as much danger when the sequence numbers
1651                  *    got wrapped.  So some stacks don't include TS on empty
1652                  *    ACKs :-(
1653                  *
1654                  * To minimize the disruption to mostly RFC1323 conformant
1655                  * stacks, we will only require timestamps on data packets.
1656                  *
1657                  * And what do ya know, we cannot require timestamps on data
1658                  * packets.  There appear to be devices that do legitimate
1659                  * TCP connection hijacking.  There are HTTP devices that allow
1660                  * a 3whs (with timestamps) and then buffer the HTTP request.
1661                  * If the intermediate device has the HTTP response cache, it
1662                  * will spoof the response but not bother timestamping its
1663                  * packets.  So we can look for the presence of a timestamp in
1664                  * the first data packet and if there, require it in all future
1665                  * packets.
1666                  */
1667
1668                 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) {
1669                         /*
1670                          * Hey!  Someone tried to sneak a packet in.  Or the
1671                          * stack changed its RFC1323 behavior?!?!
1672                          */
1673                         if (V_pf_status.debug >= PF_DEBUG_MISC) {
1674                                 DPFPRINTF(("Did not receive expected RFC1323 "
1675                                     "timestamp\n"));
1676                                 pf_print_state(state);
1677                                 pf_print_flags(th->th_flags);
1678                                 printf("\n");
1679                         }
1680                         REASON_SET(reason, PFRES_TS);
1681                         return (PF_DROP);
1682                 }
1683         }
1684
1685
1686         /*
1687          * We will note if a host sends his data packets with or without
1688          * timestamps.  And require all data packets to contain a timestamp
1689          * if the first does.  PAWS implicitly requires that all data packets be
1690          * timestamped.  But I think there are middle-man devices that hijack
1691          * TCP streams immediately after the 3whs and don't timestamp their
1692          * packets (seen in a WWW accelerator or cache).
1693          */
1694         if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags &
1695             (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) {
1696                 if (got_ts)
1697                         src->scrub->pfss_flags |= PFSS_DATA_TS;
1698                 else {
1699                         src->scrub->pfss_flags |= PFSS_DATA_NOTS;
1700                         if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub &&
1701                             (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) {
1702                                 /* Don't warn if other host rejected RFC1323 */
1703                                 DPFPRINTF(("Broken RFC1323 stack did not "
1704                                     "timestamp data packet. Disabled PAWS "
1705                                     "security.\n"));
1706                                 pf_print_state(state);
1707                                 pf_print_flags(th->th_flags);
1708                                 printf("\n");
1709                         }
1710                 }
1711         }
1712
1713
1714         /*
1715          * Update PAWS values
1716          */
1717         if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags &
1718             (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) {
1719                 getmicrouptime(&src->scrub->pfss_last);
1720                 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) ||
1721                     (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1722                         src->scrub->pfss_tsval = tsval;
1723
1724                 if (tsecr) {
1725                         if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) ||
1726                             (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1727                                 src->scrub->pfss_tsecr = tsecr;
1728
1729                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 &&
1730                             (SEQ_LT(tsval, src->scrub->pfss_tsval0) ||
1731                             src->scrub->pfss_tsval0 == 0)) {
1732                                 /* tsval0 MUST be the lowest timestamp */
1733                                 src->scrub->pfss_tsval0 = tsval;
1734                         }
1735
1736                         /* Only fully initialized after a TS gets echoed */
1737                         if ((src->scrub->pfss_flags & PFSS_PAWS) == 0)
1738                                 src->scrub->pfss_flags |= PFSS_PAWS;
1739                 }
1740         }
1741
1742         /* I have a dream....  TCP segment reassembly.... */
1743         return (0);
1744 }
1745
1746 static int
1747 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th,
1748     int off, sa_family_t af)
1749 {
1750         u_int16_t       *mss;
1751         int              thoff;
1752         int              opt, cnt, optlen = 0;
1753         int              rewrite = 0;
1754         u_char           opts[TCP_MAXOLEN];
1755         u_char          *optp = opts;
1756
1757         thoff = th->th_off << 2;
1758         cnt = thoff - sizeof(struct tcphdr);
1759
1760         if (cnt > 0 && !pf_pull_hdr(m, off + sizeof(*th), opts, cnt,
1761             NULL, NULL, af))
1762                 return (rewrite);
1763
1764         for (; cnt > 0; cnt -= optlen, optp += optlen) {
1765                 opt = optp[0];
1766                 if (opt == TCPOPT_EOL)
1767                         break;
1768                 if (opt == TCPOPT_NOP)
1769                         optlen = 1;
1770                 else {
1771                         if (cnt < 2)
1772                                 break;
1773                         optlen = optp[1];
1774                         if (optlen < 2 || optlen > cnt)
1775                                 break;
1776                 }
1777                 switch (opt) {
1778                 case TCPOPT_MAXSEG:
1779                         mss = (u_int16_t *)(optp + 2);
1780                         if ((ntohs(*mss)) > r->max_mss) {
1781                                 th->th_sum = pf_proto_cksum_fixup(m,
1782                                     th->th_sum, *mss, htons(r->max_mss), 0);
1783                                 *mss = htons(r->max_mss);
1784                                 rewrite = 1;
1785                         }
1786                         break;
1787                 default:
1788                         break;
1789                 }
1790         }
1791
1792         if (rewrite)
1793                 m_copyback(m, off + sizeof(*th), thoff - sizeof(*th), opts);
1794
1795         return (rewrite);
1796 }
1797
1798 #ifdef INET
1799 static void
1800 pf_scrub_ip(struct mbuf **m0, u_int32_t flags, u_int8_t min_ttl, u_int8_t tos)
1801 {
1802         struct mbuf             *m = *m0;
1803         struct ip               *h = mtod(m, struct ip *);
1804
1805         /* Clear IP_DF if no-df was requested */
1806         if (flags & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
1807                 u_int16_t ip_off = h->ip_off;
1808
1809                 h->ip_off &= htons(~IP_DF);
1810                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1811         }
1812
1813         /* Enforce a minimum ttl, may cause endless packet loops */
1814         if (min_ttl && h->ip_ttl < min_ttl) {
1815                 u_int16_t ip_ttl = h->ip_ttl;
1816
1817                 h->ip_ttl = min_ttl;
1818                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
1819         }
1820
1821         /* Enforce tos */
1822         if (flags & PFRULE_SET_TOS) {
1823                 u_int16_t       ov, nv;
1824
1825                 ov = *(u_int16_t *)h;
1826                 h->ip_tos = tos | (h->ip_tos & IPTOS_ECN_MASK);
1827                 nv = *(u_int16_t *)h;
1828
1829                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0);
1830         }
1831
1832         /* random-id, but not for fragments */
1833         if (flags & PFRULE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) {
1834                 uint16_t ip_id = h->ip_id;
1835
1836                 ip_fillid(h);
1837                 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0);
1838         }
1839 }
1840 #endif /* INET */
1841
1842 #ifdef INET6
1843 static void
1844 pf_scrub_ip6(struct mbuf **m0, u_int8_t min_ttl)
1845 {
1846         struct mbuf             *m = *m0;
1847         struct ip6_hdr          *h = mtod(m, struct ip6_hdr *);
1848
1849         /* Enforce a minimum ttl, may cause endless packet loops */
1850         if (min_ttl && h->ip6_hlim < min_ttl)
1851                 h->ip6_hlim = min_ttl;
1852 }
1853 #endif