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[netbsd-mini2440.git] / sys / dist / pf / net / pf_norm.c
blob37030c02966aaf02e11b4533e5395e6cf09af5ca
1 /* $NetBSD: pf_norm.c,v 1.20 2009/01/11 10:29:01 cegger Exp $ */
2 /* $OpenBSD: pf_norm.c,v 1.109 2007/05/28 17:16:39 henning Exp $ */
3
4 /*
5 * Copyright 2001 Niels Provos <provos@citi.umich.edu>
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
29 #include <sys/cdefs.h>
30 __KERNEL_RCSID(0, "$NetBSD: pf_norm.c,v 1.20 2009/01/11 10:29:01 cegger Exp $");
31
32 #ifdef _KERNEL_OPT
33 #include "opt_inet.h"
34 #endif
35
36 #include "pflog.h"
37
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/mbuf.h>
41 #include <sys/filio.h>
42 #include <sys/fcntl.h>
43 #include <sys/socket.h>
44 #include <sys/kernel.h>
45 #include <sys/time.h>
46 #include <sys/pool.h>
47
48 #ifdef __NetBSD__
49 #include <sys/rnd.h>
50 #else
51 #include <dev/rndvar.h>
52 #endif /* !__NetBSD__ */
53 #include <net/if.h>
54 #include <net/if_types.h>
55 #include <net/bpf.h>
56 #include <net/route.h>
57 #include <net/if_pflog.h>
58
59 #include <netinet/in.h>
60 #include <netinet/in_var.h>
61 #include <netinet/in_systm.h>
62 #include <netinet/ip.h>
63 #include <netinet/ip_var.h>
64 #include <netinet/tcp.h>
65 #include <netinet/tcp_seq.h>
66 #include <netinet/udp.h>
67 #include <netinet/ip_icmp.h>
68
69 #ifdef INET6
70 #include <netinet/ip6.h>
71 #endif /* INET6 */
72
73 #include <net/pfvar.h>
74
75 struct pf_frent {
76 LIST_ENTRY(pf_frent) fr_next;
77 struct ip *fr_ip;
78 struct mbuf *fr_m;
79 };
80
81 struct pf_frcache {
82 LIST_ENTRY(pf_frcache) fr_next;
83 uint16_t fr_off;
84 uint16_t fr_end;
85 };
86
87 #define PFFRAG_SEENLAST 0x0001 /* Seen the last fragment for this */
88 #define PFFRAG_NOBUFFER 0x0002 /* Non-buffering fragment cache */
89 #define PFFRAG_DROP 0x0004 /* Drop all fragments */
90 #define BUFFER_FRAGMENTS(fr) (!((fr)->fr_flags & PFFRAG_NOBUFFER))
91
92 struct pf_fragment {
93 RB_ENTRY(pf_fragment) fr_entry;
94 TAILQ_ENTRY(pf_fragment) frag_next;
95 struct in_addr fr_src;
96 struct in_addr fr_dst;
97 u_int8_t fr_p; /* protocol of this fragment */
98 u_int8_t fr_flags; /* status flags */
99 u_int16_t fr_id; /* fragment id for reassemble */
100 u_int16_t fr_max; /* fragment data max */
101 u_int32_t fr_timeout;
102 #define fr_queue fr_u.fru_queue
103 #define fr_cache fr_u.fru_cache
104 union {
105 LIST_HEAD(pf_fragq, pf_frent) fru_queue; /* buffering */
106 LIST_HEAD(pf_cacheq, pf_frcache) fru_cache; /* non-buf */
107 } fr_u;
108 };
109
110 TAILQ_HEAD(pf_fragqueue, pf_fragment) pf_fragqueue;
111 TAILQ_HEAD(pf_cachequeue, pf_fragment) pf_cachequeue;
112
113 static __inline int pf_frag_compare(struct pf_fragment *,
114 struct pf_fragment *);
115 RB_HEAD(pf_frag_tree, pf_fragment) pf_frag_tree, pf_cache_tree;
116 RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
117 RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
118
119 /* Private prototypes */
120 void pf_ip2key(struct pf_fragment *, struct ip *);
121 void pf_remove_fragment(struct pf_fragment *);
122 void pf_flush_fragments(void);
123 void pf_free_fragment(struct pf_fragment *);
124 struct pf_fragment *pf_find_fragment(struct ip *, struct pf_frag_tree *);
125 struct mbuf *pf_reassemble(struct mbuf **, struct pf_fragment **,
126 struct pf_frent *, int);
127 struct mbuf *pf_fragcache(struct mbuf **, struct ip*,
128 struct pf_fragment **, int, int, int *);
129 int pf_normalize_tcpopt(struct pf_rule *, struct mbuf *,
130 struct tcphdr *, int);
131
132 #define DPFPRINTF(x) do { \
133 if (pf_status.debug >= PF_DEBUG_MISC) { \
134 printf("%s: ", __func__); \
135 printf x ; \
136 } \
137 } while(0)
138
139 /* Globals */
140 struct pool pf_frent_pl, pf_frag_pl, pf_cache_pl, pf_cent_pl;
141 struct pool pf_state_scrub_pl;
142 int pf_nfrents, pf_ncache;
143
144 void
145 pf_normalize_init(void)
146 {
147 #ifdef __NetBSD__
148 pool_init(&pf_frent_pl, sizeof(struct pf_frent), 0, 0, 0, "pffrent",
149 NULL, IPL_SOFTNET);
150 pool_init(&pf_frag_pl, sizeof(struct pf_fragment), 0, 0, 0, "pffrag",
151 NULL, IPL_SOFTNET);
152 pool_init(&pf_cache_pl, sizeof(struct pf_fragment), 0, 0, 0,
153 "pffrcache", NULL, IPL_SOFTNET);
154 pool_init(&pf_cent_pl, sizeof(struct pf_frcache), 0, 0, 0, "pffrcent",
155 NULL, IPL_SOFTNET);
156 pool_init(&pf_state_scrub_pl, sizeof(struct pf_state_scrub), 0, 0, 0,
157 "pfstscr", NULL, IPL_SOFTNET);
158 #else
159 pool_init(&pf_frent_pl, sizeof(struct pf_frent), 0, 0, 0, "pffrent",
160 NULL);
161 pool_init(&pf_frag_pl, sizeof(struct pf_fragment), 0, 0, 0, "pffrag",
162 NULL);
163 pool_init(&pf_cache_pl, sizeof(struct pf_fragment), 0, 0, 0,
164 "pffrcache", NULL);
165 pool_init(&pf_cent_pl, sizeof(struct pf_frcache), 0, 0, 0, "pffrcent",
166 NULL);
167 pool_init(&pf_state_scrub_pl, sizeof(struct pf_state_scrub), 0, 0, 0,
168 "pfstscr", NULL);
169 #endif /* !__NetBSD__ */
170
171 pool_sethiwat(&pf_frag_pl, PFFRAG_FRAG_HIWAT);
172 pool_sethardlimit(&pf_frent_pl, PFFRAG_FRENT_HIWAT, NULL, 0);
173 pool_sethardlimit(&pf_cache_pl, PFFRAG_FRCACHE_HIWAT, NULL, 0);
174 pool_sethardlimit(&pf_cent_pl, PFFRAG_FRCENT_HIWAT, NULL, 0);
175
176 TAILQ_INIT(&pf_fragqueue);
177 TAILQ_INIT(&pf_cachequeue);
178 }
179
180 static __inline int
181 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b)
182 {
183 int diff;
184
185 if ((diff = a->fr_id - b->fr_id))
186 return (diff);
187 else if ((diff = a->fr_p - b->fr_p))
188 return (diff);
189 else if (a->fr_src.s_addr < b->fr_src.s_addr)
190 return (-1);
191 else if (a->fr_src.s_addr > b->fr_src.s_addr)
192 return (1);
193 else if (a->fr_dst.s_addr < b->fr_dst.s_addr)
194 return (-1);
195 else if (a->fr_dst.s_addr > b->fr_dst.s_addr)
196 return (1);
197 return (0);
198 }
199
200 void
201 pf_purge_expired_fragments(void)
202 {
203 struct pf_fragment *frag;
204 u_int32_t expire = time_second -
205 pf_default_rule.timeout[PFTM_FRAG];
206
207 while ((frag = TAILQ_LAST(&pf_fragqueue, pf_fragqueue)) != NULL) {
208 KASSERT(BUFFER_FRAGMENTS(frag));
209 if (frag->fr_timeout > expire)
210 break;
211
212 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
213 pf_free_fragment(frag);
214 }
215
216 while ((frag = TAILQ_LAST(&pf_cachequeue, pf_cachequeue)) != NULL) {
217 KASSERT(!BUFFER_FRAGMENTS(frag));
218 if (frag->fr_timeout > expire)
219 break;
220
221 DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
222 pf_free_fragment(frag);
223 KASSERT(TAILQ_EMPTY(&pf_cachequeue) ||
224 TAILQ_LAST(&pf_cachequeue, pf_cachequeue) != frag);
225 }
226 }
227
228 /*
229 * Try to flush old fragments to make space for new ones
230 */
231
232 void
233 pf_flush_fragments(void)
234 {
235 struct pf_fragment *frag;
236 int goal;
237
238 goal = pf_nfrents * 9 / 10;
239 DPFPRINTF(("trying to free > %d frents\n",
240 pf_nfrents - goal));
241 while (goal < pf_nfrents) {
242 frag = TAILQ_LAST(&pf_fragqueue, pf_fragqueue);
243 if (frag == NULL)
244 break;
245 pf_free_fragment(frag);
246 }
247
248
249 goal = pf_ncache * 9 / 10;
250 DPFPRINTF(("trying to free > %d cache entries\n",
251 pf_ncache - goal));
252 while (goal < pf_ncache) {
253 frag = TAILQ_LAST(&pf_cachequeue, pf_cachequeue);
254 if (frag == NULL)
255 break;
256 pf_free_fragment(frag);
257 }
258 }
259
260 /* Frees the fragments and all associated entries */
261
262 void
263 pf_free_fragment(struct pf_fragment *frag)
264 {
265 struct pf_frent *frent;
266 struct pf_frcache *frcache;
267
268 /* Free all fragments */
269 if (BUFFER_FRAGMENTS(frag)) {
270 for (frent = LIST_FIRST(&frag->fr_queue); frent;
271 frent = LIST_FIRST(&frag->fr_queue)) {
272 LIST_REMOVE(frent, fr_next);
273
274 m_freem(frent->fr_m);
275 pool_put(&pf_frent_pl, frent);
276 pf_nfrents--;
277 }
278 } else {
279 for (frcache = LIST_FIRST(&frag->fr_cache); frcache;
280 frcache = LIST_FIRST(&frag->fr_cache)) {
281 LIST_REMOVE(frcache, fr_next);
282
283 KASSERT(LIST_EMPTY(&frag->fr_cache) ||
284 LIST_FIRST(&frag->fr_cache)->fr_off >
285 frcache->fr_end);
286
287 pool_put(&pf_cent_pl, frcache);
288 pf_ncache--;
289 }
290 }
291
292 pf_remove_fragment(frag);
293 }
294
295 void
296 pf_ip2key(struct pf_fragment *key, struct ip *ip)
297 {
298 key->fr_p = ip->ip_p;
299 key->fr_id = ip->ip_id;
300 key->fr_src.s_addr = ip->ip_src.s_addr;
301 key->fr_dst.s_addr = ip->ip_dst.s_addr;
302 }
303
304 struct pf_fragment *
305 pf_find_fragment(struct ip *ip, struct pf_frag_tree *tree)
306 {
307 struct pf_fragment key;
308 struct pf_fragment *frag;
309
310 pf_ip2key(&key, ip);
311
312 frag = RB_FIND(pf_frag_tree, tree, &key);
313 if (frag != NULL) {
314 /* XXX Are we sure we want to update the timeout? */
315 frag->fr_timeout = time_second;
316 if (BUFFER_FRAGMENTS(frag)) {
317 TAILQ_REMOVE(&pf_fragqueue, frag, frag_next);
318 TAILQ_INSERT_HEAD(&pf_fragqueue, frag, frag_next);
319 } else {
320 TAILQ_REMOVE(&pf_cachequeue, frag, frag_next);
321 TAILQ_INSERT_HEAD(&pf_cachequeue, frag, frag_next);
322 }
323 }
324
325 return (frag);
326 }
327
328 /* Removes a fragment from the fragment queue and frees the fragment */
329
330 void
331 pf_remove_fragment(struct pf_fragment *frag)
332 {
333 if (BUFFER_FRAGMENTS(frag)) {
334 RB_REMOVE(pf_frag_tree, &pf_frag_tree, frag);
335 TAILQ_REMOVE(&pf_fragqueue, frag, frag_next);
336 pool_put(&pf_frag_pl, frag);
337 } else {
338 RB_REMOVE(pf_frag_tree, &pf_cache_tree, frag);
339 TAILQ_REMOVE(&pf_cachequeue, frag, frag_next);
340 pool_put(&pf_cache_pl, frag);
341 }
342 }
343
344 #define FR_IP_OFF(fr) ((ntohs((fr)->fr_ip->ip_off) & IP_OFFMASK) << 3)
345 struct mbuf *
346 pf_reassemble(struct mbuf **m0, struct pf_fragment **frag,
347 struct pf_frent *frent, int mff)
348 {
349 struct mbuf *m = *m0, *m2;
350 struct pf_frent *frea, *next;
351 struct pf_frent *frep = NULL;
352 struct ip *ip = frent->fr_ip;
353 int hlen = ip->ip_hl << 2;
354 u_int16_t off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3;
355 u_int16_t ip_len = ntohs(ip->ip_len) - ip->ip_hl * 4;
356 u_int16_t max = ip_len + off;
357
358 KASSERT(*frag == NULL || BUFFER_FRAGMENTS(*frag));
359
360 /* Strip off ip header */
361 m->m_data += hlen;
362 m->m_len -= hlen;
363
364 /* Create a new reassembly queue for this packet */
365 if (*frag == NULL) {
366 *frag = pool_get(&pf_frag_pl, PR_NOWAIT);
367 if (*frag == NULL) {
368 pf_flush_fragments();
369 *frag = pool_get(&pf_frag_pl, PR_NOWAIT);
370 if (*frag == NULL)
371 goto drop_fragment;
372 }
373
374 (*frag)->fr_flags = 0;
375 (*frag)->fr_max = 0;
376 (*frag)->fr_src = frent->fr_ip->ip_src;
377 (*frag)->fr_dst = frent->fr_ip->ip_dst;
378 (*frag)->fr_p = frent->fr_ip->ip_p;
379 (*frag)->fr_id = frent->fr_ip->ip_id;
380 (*frag)->fr_timeout = time_second;
381 LIST_INIT(&(*frag)->fr_queue);
382
383 RB_INSERT(pf_frag_tree, &pf_frag_tree, *frag);
384 TAILQ_INSERT_HEAD(&pf_fragqueue, *frag, frag_next);
385
386 /* We do not have a previous fragment */
387 frep = NULL;
388 goto insert;
389 }
390
391 /*
392 * Find a fragment after the current one:
393 * - off contains the real shifted offset.
394 */
395 LIST_FOREACH(frea, &(*frag)->fr_queue, fr_next) {
396 if (FR_IP_OFF(frea) > off)
397 break;
398 frep = frea;
399 }
400
401 KASSERT(frep != NULL || frea != NULL);
402
403 if (frep != NULL &&
404 FR_IP_OFF(frep) + ntohs(frep->fr_ip->ip_len) - frep->fr_ip->ip_hl *
405 4 > off)
406 {
407 u_int16_t precut;
408
409 precut = FR_IP_OFF(frep) + ntohs(frep->fr_ip->ip_len) -
410 frep->fr_ip->ip_hl * 4 - off;
411 if (precut >= ip_len)
412 goto drop_fragment;
413 m_adj(frent->fr_m, precut);
414 DPFPRINTF(("overlap -%d\n", precut));
415 /* Enforce 8 byte boundaries */
416 ip->ip_off = htons(ntohs(ip->ip_off) + (precut >> 3));
417 off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3;
418 ip_len -= precut;
419 ip->ip_len = htons(ip_len);
420 }
421
422 for (; frea != NULL && ip_len + off > FR_IP_OFF(frea);
423 frea = next)
424 {
425 u_int16_t aftercut;
426
427 aftercut = ip_len + off - FR_IP_OFF(frea);
428 DPFPRINTF(("adjust overlap %d\n", aftercut));
429 if (aftercut < ntohs(frea->fr_ip->ip_len) - frea->fr_ip->ip_hl
430 * 4)
431 {
432 frea->fr_ip->ip_len =
433 htons(ntohs(frea->fr_ip->ip_len) - aftercut);
434 frea->fr_ip->ip_off = htons(ntohs(frea->fr_ip->ip_off) +
435 (aftercut >> 3));
436 m_adj(frea->fr_m, aftercut);
437 break;
438 }
439
440 /* This fragment is completely overlapped, lose it */
441 next = LIST_NEXT(frea, fr_next);
442 m_freem(frea->fr_m);
443 LIST_REMOVE(frea, fr_next);
444 pool_put(&pf_frent_pl, frea);
445 pf_nfrents--;
446 }
447
448 insert:
449 /* Update maximum data size */
450 if ((*frag)->fr_max < max)
451 (*frag)->fr_max = max;
452 /* This is the last segment */
453 if (!mff)
454 (*frag)->fr_flags |= PFFRAG_SEENLAST;
455
456 if (frep == NULL)
457 LIST_INSERT_HEAD(&(*frag)->fr_queue, frent, fr_next);
458 else
459 LIST_INSERT_AFTER(frep, frent, fr_next);
460
461 /* Check if we are completely reassembled */
462 if (!((*frag)->fr_flags & PFFRAG_SEENLAST))
463 return (NULL);
464
465 /* Check if we have all the data */
466 off = 0;
467 for (frep = LIST_FIRST(&(*frag)->fr_queue); frep; frep = next) {
468 next = LIST_NEXT(frep, fr_next);
469
470 off += ntohs(frep->fr_ip->ip_len) - frep->fr_ip->ip_hl * 4;
471 if (off < (*frag)->fr_max &&
472 (next == NULL || FR_IP_OFF(next) != off))
473 {
474 DPFPRINTF(("missing fragment at %d, next %d, max %d\n",
475 off, next == NULL ? -1 : FR_IP_OFF(next),
476 (*frag)->fr_max));
477 return (NULL);
478 }
479 }
480 DPFPRINTF(("%d < %d?\n", off, (*frag)->fr_max));
481 if (off < (*frag)->fr_max)
482 return (NULL);
483
484 /* We have all the data */
485 frent = LIST_FIRST(&(*frag)->fr_queue);
486 KASSERT(frent != NULL);
487 if ((frent->fr_ip->ip_hl << 2) + off > IP_MAXPACKET) {
488 DPFPRINTF(("drop: too big: %d\n", off));
489 pf_free_fragment(*frag);
490 *frag = NULL;
491 return (NULL);
492 }
493 next = LIST_NEXT(frent, fr_next);
494
495 /* Magic from ip_input */
496 ip = frent->fr_ip;
497 m = frent->fr_m;
498 m2 = m->m_next;
499 m->m_next = NULL;
500 m_cat(m, m2);
501 pool_put(&pf_frent_pl, frent);
502 pf_nfrents--;
503 for (frent = next; frent != NULL; frent = next) {
504 next = LIST_NEXT(frent, fr_next);
505
506 m2 = frent->fr_m;
507 pool_put(&pf_frent_pl, frent);
508 pf_nfrents--;
509 m_cat(m, m2);
510 }
511
512 ip->ip_src = (*frag)->fr_src;
513 ip->ip_dst = (*frag)->fr_dst;
514
515 /* Remove from fragment queue */
516 pf_remove_fragment(*frag);
517 *frag = NULL;
518
519 hlen = ip->ip_hl << 2;
520 ip->ip_len = htons(off + hlen);
521 m->m_len += hlen;
522 m->m_data -= hlen;
523
524 /* some debugging cruft by sklower, below, will go away soon */
525 /* XXX this should be done elsewhere */
526 if (m->m_flags & M_PKTHDR) {
527 int plen = 0;
528 for (m2 = m; m2; m2 = m2->m_next)
529 plen += m2->m_len;
530 m->m_pkthdr.len = plen;
531 #ifdef __NetBSD__
532 m->m_pkthdr.csum_flags = 0;
533 #endif /* __NetBSD__ */
534 }
535
536 DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len)));
537 return (m);
538
539 drop_fragment:
540 /* Oops - fail safe - drop packet */
541 pool_put(&pf_frent_pl, frent);
542 pf_nfrents--;
543 m_freem(m);
544 return (NULL);
545 }
546
547 struct mbuf *
548 pf_fragcache(struct mbuf **m0, struct ip *h, struct pf_fragment **frag, int mff,
549 int drop, int *nomem)
550 {
551 struct mbuf *m = *m0;
552 struct pf_frcache *frp, *fra, *cur = NULL;
553 int ip_len = ntohs(h->ip_len) - (h->ip_hl << 2);
554 u_int16_t off = ntohs(h->ip_off) << 3;
555 u_int16_t max = ip_len + off;
556 int hosed = 0;
557
558 KASSERT(*frag == NULL || !BUFFER_FRAGMENTS(*frag));
559
560 /* Create a new range queue for this packet */
561 if (*frag == NULL) {
562 *frag = pool_get(&pf_cache_pl, PR_NOWAIT);
563 if (*frag == NULL) {
564 pf_flush_fragments();
565 *frag = pool_get(&pf_cache_pl, PR_NOWAIT);
566 if (*frag == NULL)
567 goto no_mem;
568 }
569
570 /* Get an entry for the queue */
571 cur = pool_get(&pf_cent_pl, PR_NOWAIT);
572 if (cur == NULL) {
573 pool_put(&pf_cache_pl, *frag);
574 *frag = NULL;
575 goto no_mem;
576 }
577 pf_ncache++;
578
579 (*frag)->fr_flags = PFFRAG_NOBUFFER;
580 (*frag)->fr_max = 0;
581 (*frag)->fr_src = h->ip_src;
582 (*frag)->fr_dst = h->ip_dst;
583 (*frag)->fr_p = h->ip_p;
584 (*frag)->fr_id = h->ip_id;
585 (*frag)->fr_timeout = time_second;
586
587 cur->fr_off = off;
588 cur->fr_end = max;
589 LIST_INIT(&(*frag)->fr_cache);
590 LIST_INSERT_HEAD(&(*frag)->fr_cache, cur, fr_next);
591
592 RB_INSERT(pf_frag_tree, &pf_cache_tree, *frag);
593 TAILQ_INSERT_HEAD(&pf_cachequeue, *frag, frag_next);
594
595 DPFPRINTF(("fragcache[%d]: new %d-%d\n", h->ip_id, off, max));
596
597 goto pass;
598 }
599
600 /*
601 * Find a fragment after the current one:
602 * - off contains the real shifted offset.
603 */
604 frp = NULL;
605 LIST_FOREACH(fra, &(*frag)->fr_cache, fr_next) {
606 if (fra->fr_off > off)
607 break;
608 frp = fra;
609 }
610
611 KASSERT(frp != NULL || fra != NULL);
612
613 if (frp != NULL) {
614 int precut;
615
616 precut = frp->fr_end - off;
617 if (precut >= ip_len) {
618 /* Fragment is entirely a duplicate */
619 DPFPRINTF(("fragcache[%d]: dead (%d-%d) %d-%d\n",
620 h->ip_id, frp->fr_off, frp->fr_end, off, max));
621 goto drop_fragment;
622 }
623 if (precut == 0) {
624 /* They are adjacent. Fixup cache entry */
625 DPFPRINTF(("fragcache[%d]: adjacent (%d-%d) %d-%d\n",
626 h->ip_id, frp->fr_off, frp->fr_end, off, max));
627 frp->fr_end = max;
628 } else if (precut > 0) {
629 /* The first part of this payload overlaps with a
630 * fragment that has already been passed.
631 * Need to trim off the first part of the payload.
632 * But to do so easily, we need to create another
633 * mbuf to throw the original header into.
634 */
635
636 DPFPRINTF(("fragcache[%d]: chop %d (%d-%d) %d-%d\n",
637 h->ip_id, precut, frp->fr_off, frp->fr_end, off,
638 max));
639
640 off += precut;
641 max -= precut;
642 /* Update the previous frag to encompass this one */
643 frp->fr_end = max;
644
645 if (!drop) {
646 /* XXX Optimization opportunity
647 * This is a very heavy way to trim the payload.
648 * we could do it much faster by diddling mbuf
649 * internals but that would be even less legible
650 * than this mbuf magic. For my next trick,
651 * I'll pull a rabbit out of my laptop.
652 */
653 *m0 = m_dup(m, 0, h->ip_hl << 2, M_NOWAIT);
654 if (*m0 == NULL)
655 goto no_mem;
656 KASSERT((*m0)->m_next == NULL);
657 m_adj(m, precut + (h->ip_hl << 2));
658 m_cat(*m0, m);
659 m = *m0;
660 if (m->m_flags & M_PKTHDR) {
661 int plen = 0;
662 struct mbuf *t;
663 for (t = m; t; t = t->m_next)
664 plen += t->m_len;
665 m->m_pkthdr.len = plen;
666 }
667
668
669 h = mtod(m, struct ip *);
670
671
672 KASSERT((int)m->m_len ==
673 ntohs(h->ip_len) - precut);
674 h->ip_off = htons(ntohs(h->ip_off) +
675 (precut >> 3));
676 h->ip_len = htons(ntohs(h->ip_len) - precut);
677 } else {
678 hosed++;
679 }
680 } else {
681 /* There is a gap between fragments */
682
683 DPFPRINTF(("fragcache[%d]: gap %d (%d-%d) %d-%d\n",
684 h->ip_id, -precut, frp->fr_off, frp->fr_end, off,
685 max));
686
687 cur = pool_get(&pf_cent_pl, PR_NOWAIT);
688 if (cur == NULL)
689 goto no_mem;
690 pf_ncache++;
691
692 cur->fr_off = off;
693 cur->fr_end = max;
694 LIST_INSERT_AFTER(frp, cur, fr_next);
695 }
696 }
697
698 if (fra != NULL) {
699 int aftercut;
700 int merge = 0;
701
702 aftercut = max - fra->fr_off;
703 if (aftercut == 0) {
704 /* Adjacent fragments */
705 DPFPRINTF(("fragcache[%d]: adjacent %d-%d (%d-%d)\n",
706 h->ip_id, off, max, fra->fr_off, fra->fr_end));
707 fra->fr_off = off;
708 merge = 1;
709 } else if (aftercut > 0) {
710 /* Need to chop off the tail of this fragment */
711 DPFPRINTF(("fragcache[%d]: chop %d %d-%d (%d-%d)\n",
712 h->ip_id, aftercut, off, max, fra->fr_off,
713 fra->fr_end));
714 fra->fr_off = off;
715 max -= aftercut;
716
717 merge = 1;
718
719 if (!drop) {
720 m_adj(m, -aftercut);
721 if (m->m_flags & M_PKTHDR) {
722 int plen = 0;
723 struct mbuf *t;
724 for (t = m; t; t = t->m_next)
725 plen += t->m_len;
726 m->m_pkthdr.len = plen;
727 }
728 h = mtod(m, struct ip *);
729 KASSERT((int)m->m_len ==
730 ntohs(h->ip_len) - aftercut);
731 h->ip_len = htons(ntohs(h->ip_len) - aftercut);
732 } else {
733 hosed++;
734 }
735 } else if (frp == NULL) {
736 /* There is a gap between fragments */
737 DPFPRINTF(("fragcache[%d]: gap %d %d-%d (%d-%d)\n",
738 h->ip_id, -aftercut, off, max, fra->fr_off,
739 fra->fr_end));
740
741 cur = pool_get(&pf_cent_pl, PR_NOWAIT);
742 if (cur == NULL)
743 goto no_mem;
744 pf_ncache++;
745
746 cur->fr_off = off;
747 cur->fr_end = max;
748 LIST_INSERT_BEFORE(fra, cur, fr_next);
749 }
750
751
752 /* Need to glue together two separate fragment descriptors */
753 if (merge) {
754 if (cur && fra->fr_off <= cur->fr_end) {
755 /* Need to merge in a previous 'cur' */
756 DPFPRINTF(("fragcache[%d]: adjacent(merge "
757 "%d-%d) %d-%d (%d-%d)\n",
758 h->ip_id, cur->fr_off, cur->fr_end, off,
759 max, fra->fr_off, fra->fr_end));
760 fra->fr_off = cur->fr_off;
761 LIST_REMOVE(cur, fr_next);
762 pool_put(&pf_cent_pl, cur);
763 pf_ncache--;
764 cur = NULL;
765
766 } else if (frp && fra->fr_off <= frp->fr_end) {
767 /* Need to merge in a modified 'frp' */
768 KASSERT(cur == NULL);
769 DPFPRINTF(("fragcache[%d]: adjacent(merge "
770 "%d-%d) %d-%d (%d-%d)\n",
771 h->ip_id, frp->fr_off, frp->fr_end, off,
772 max, fra->fr_off, fra->fr_end));
773 fra->fr_off = frp->fr_off;
774 LIST_REMOVE(frp, fr_next);
775 pool_put(&pf_cent_pl, frp);
776 pf_ncache--;
777 frp = NULL;
778
779 }
780 }
781 }
782
783 if (hosed) {
784 /*
785 * We must keep tracking the overall fragment even when
786 * we're going to drop it anyway so that we know when to
787 * free the overall descriptor. Thus we drop the frag late.
788 */
789 goto drop_fragment;
790 }
791
792
793 pass:
794 /* Update maximum data size */
795 if ((*frag)->fr_max < max)
796 (*frag)->fr_max = max;
797
798 /* This is the last segment */
799 if (!mff)
800 (*frag)->fr_flags |= PFFRAG_SEENLAST;
801
802 /* Check if we are completely reassembled */
803 if (((*frag)->fr_flags & PFFRAG_SEENLAST) &&
804 LIST_FIRST(&(*frag)->fr_cache)->fr_off == 0 &&
805 LIST_FIRST(&(*frag)->fr_cache)->fr_end == (*frag)->fr_max) {
806 /* Remove from fragment queue */
807 DPFPRINTF(("fragcache[%d]: done 0-%d\n", h->ip_id,
808 (*frag)->fr_max));
809 pf_free_fragment(*frag);
810 *frag = NULL;
811 }
812
813 return (m);
814
815 no_mem:
816 *nomem = 1;
817
818 /* Still need to pay attention to !IP_MF */
819 if (!mff && *frag != NULL)
820 (*frag)->fr_flags |= PFFRAG_SEENLAST;
821
822 m_freem(m);
823 return (NULL);
824
825 drop_fragment:
826
827 /* Still need to pay attention to !IP_MF */
828 if (!mff && *frag != NULL)
829 (*frag)->fr_flags |= PFFRAG_SEENLAST;
830
831 if (drop) {
832 /* This fragment has been deemed bad. Don't reass */
833 if (((*frag)->fr_flags & PFFRAG_DROP) == 0)
834 DPFPRINTF(("fragcache[%d]: dropping overall fragment\n",
835 h->ip_id));
836 (*frag)->fr_flags |= PFFRAG_DROP;
837 }
838
839 m_freem(m);
840 return (NULL);
841 }
842
843 int
844 pf_normalize_ip(struct mbuf **m0, int dir, struct pfi_kif *kif, u_short *reason,
845 struct pf_pdesc *pd)
846 {
847 struct mbuf *m = *m0;
848 struct pf_rule *r;
849 struct pf_frent *frent;
850 struct pf_fragment *frag = NULL;
851 struct ip *h = mtod(m, struct ip *);
852 int mff = (ntohs(h->ip_off) & IP_MF);
853 int hlen = h->ip_hl << 2;
854 u_int16_t fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
855 u_int16_t max;
856 int ip_len;
857 int ip_off;
858
859 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
860 while (r != NULL) {
861 r->evaluations++;
862 if (pfi_kif_match(r->kif, kif) == r->ifnot)
863 r = r->skip[PF_SKIP_IFP].ptr;
864 else if (r->direction && r->direction != dir)
865 r = r->skip[PF_SKIP_DIR].ptr;
866 else if (r->af && r->af != AF_INET)
867 r = r->skip[PF_SKIP_AF].ptr;
868 else if (r->proto && r->proto != h->ip_p)
869 r = r->skip[PF_SKIP_PROTO].ptr;
870 else if (PF_MISMATCHAW(&r->src.addr,
871 (struct pf_addr *)&h->ip_src.s_addr, AF_INET,
872 r->src.neg, kif))
873 r = r->skip[PF_SKIP_SRC_ADDR].ptr;
874 else if (PF_MISMATCHAW(&r->dst.addr,
875 (struct pf_addr *)&h->ip_dst.s_addr, AF_INET,
876 r->dst.neg, NULL))
877 r = r->skip[PF_SKIP_DST_ADDR].ptr;
878 else
879 break;
880 }
881
882 if (r == NULL || r->action == PF_NOSCRUB)
883 return (PF_PASS);
884 else {
885 r->packets[dir == PF_OUT]++;
886 r->bytes[dir == PF_OUT] += pd->tot_len;
887 }
888
889 /* Check for illegal packets */
890 if (hlen < (int)sizeof(struct ip))
891 goto drop;
892
893 if (hlen > ntohs(h->ip_len))
894 goto drop;
895
896 /* Clear IP_DF if the rule uses the no-df option */
897 if (r->rule_flag & PFRULE_NODF && h->ip_off & htons(IP_DF)) {
898 u_int16_t ip_off = h->ip_off;
899
900 h->ip_off &= htons(~IP_DF);
901 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
902 }
903
904 /* We will need other tests here */
905 if (!fragoff && !mff)
906 goto no_fragment;
907
908 /* We're dealing with a fragment now. Don't allow fragments
909 * with IP_DF to enter the cache. If the flag was cleared by
910 * no-df above, fine. Otherwise drop it.
911 */
912 if (h->ip_off & htons(IP_DF)) {
913 DPFPRINTF(("IP_DF\n"));
914 goto bad;
915 }
916
917 ip_len = ntohs(h->ip_len) - hlen;
918 ip_off = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
919
920 /* All fragments are 8 byte aligned */
921 if (mff && (ip_len & 0x7)) {
922 DPFPRINTF(("mff and %d\n", ip_len));
923 goto bad;
924 }
925
926 /* Respect maximum length */
927 if (fragoff + ip_len > IP_MAXPACKET) {
928 DPFPRINTF(("max packet %d\n", fragoff + ip_len));
929 goto bad;
930 }
931 max = fragoff + ip_len;
932
933 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0) {
934 /* Fully buffer all of the fragments */
935
936 frag = pf_find_fragment(h, &pf_frag_tree);
937
938 /* Check if we saw the last fragment already */
939 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
940 max > frag->fr_max)
941 goto bad;
942
943 /* Get an entry for the fragment queue */
944 frent = pool_get(&pf_frent_pl, PR_NOWAIT);
945 if (frent == NULL) {
946 REASON_SET(reason, PFRES_MEMORY);
947 return (PF_DROP);
948 }
949 pf_nfrents++;
950 frent->fr_ip = h;
951 frent->fr_m = m;
952
953 /* Might return a completely reassembled mbuf, or NULL */
954 DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
955 *m0 = m = pf_reassemble(m0, &frag, frent, mff);
956
957 if (m == NULL)
958 return (PF_DROP);
959
960 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
961 goto drop;
962
963 h = mtod(m, struct ip *);
964 } else {
965 /* non-buffering fragment cache (drops or masks overlaps) */
966 int nomem = 0;
967
968 #ifdef __NetBSD__
969 struct pf_mtag *pf_mtag = pf_find_mtag(m);
970 KASSERT(pf_mtag != NULL);
971
972 if (dir == PF_OUT && pf_mtag->flags & PF_TAG_FRAGCACHE) {
973 #else
974 if (dir == PF_OUT && m->m_pkthdr.pf.flags & PF_TAG_FRAGCACHE) {
975 #endif /* !__NetBSD__ */
976 /*
977 * Already passed the fragment cache in the
978 * input direction. If we continued, it would
979 * appear to be a dup and would be dropped.
980 */
981 goto fragment_pass;
982 }
983
984 frag = pf_find_fragment(h, &pf_cache_tree);
985
986 /* Check if we saw the last fragment already */
987 if (frag != NULL && (frag->fr_flags & PFFRAG_SEENLAST) &&
988 max > frag->fr_max) {
989 if (r->rule_flag & PFRULE_FRAGDROP)
990 frag->fr_flags |= PFFRAG_DROP;
991 goto bad;
992 }
993
994 *m0 = m = pf_fragcache(m0, h, &frag, mff,
995 (r->rule_flag & PFRULE_FRAGDROP) ? 1 : 0, &nomem);
996 if (m == NULL) {
997 if (nomem)
998 goto no_mem;
999 goto drop;
1000 }
1001
1002 if (dir == PF_IN)
1003 #ifdef __NetBSD__
1004 pf_mtag = pf_find_mtag(m);
1005 KASSERT(pf_mtag != NULL);
1006
1007 pf_mtag->flags |= PF_TAG_FRAGCACHE;
1008 #else
1009 m->m_pkthdr.pf.flags |= PF_TAG_FRAGCACHE;
1010 #endif /* !__NetBSD__ */
1011
1012 if (frag != NULL && (frag->fr_flags & PFFRAG_DROP))
1013 goto drop;
1014 goto fragment_pass;
1015 }
1016
1017 no_fragment:
1018 /* At this point, only IP_DF is allowed in ip_off */
1019 if (h->ip_off & ~htons(IP_DF)) {
1020 u_int16_t ip_off = h->ip_off;
1021
1022 h->ip_off &= htons(IP_DF);
1023 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1024 }
1025
1026 /* Enforce a minimum ttl, may cause endless packet loops */
1027 if (r->min_ttl && h->ip_ttl < r->min_ttl) {
1028 u_int16_t ip_ttl = h->ip_ttl;
1029
1030 h->ip_ttl = r->min_ttl;
1031 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
1032 }
1033
1034 if (r->rule_flag & PFRULE_RANDOMID) {
1035 u_int16_t ip_id = h->ip_id;
1036
1037 h->ip_id = ip_randomid(0);
1038 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0);
1039 }
1040 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0)
1041 pd->flags |= PFDESC_IP_REAS;
1042
1043 return (PF_PASS);
1044
1045 fragment_pass:
1046 /* Enforce a minimum ttl, may cause endless packet loops */
1047 if (r->min_ttl && h->ip_ttl < r->min_ttl) {
1048 u_int16_t ip_ttl = h->ip_ttl;
1049
1050 h->ip_ttl = r->min_ttl;
1051 h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
1052 }
1053 if ((r->rule_flag & (PFRULE_FRAGCROP|PFRULE_FRAGDROP)) == 0)
1054 pd->flags |= PFDESC_IP_REAS;
1055 return (PF_PASS);
1056
1057 no_mem:
1058 REASON_SET(reason, PFRES_MEMORY);
1059 if (r != NULL && r->log)
1060 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL, pd);
1061 return (PF_DROP);
1062
1063 drop:
1064 REASON_SET(reason, PFRES_NORM);
1065 if (r != NULL && r->log)
1066 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL, pd);
1067 return (PF_DROP);
1068
1069 bad:
1070 DPFPRINTF(("dropping bad fragment\n"));
1071
1072 /* Free associated fragments */
1073 if (frag != NULL)
1074 pf_free_fragment(frag);
1075
1076 REASON_SET(reason, PFRES_FRAG);
1077 if (r != NULL && r->log)
1078 PFLOG_PACKET(kif, h, m, AF_INET, dir, *reason, r, NULL, NULL, pd);
1079
1080 return (PF_DROP);
1081 }
1082
1083 #ifdef INET6
1084 int
1085 pf_normalize_ip6(struct mbuf **m0, int dir, struct pfi_kif *kif,
1086 u_short *reason, struct pf_pdesc *pd)
1087 {
1088 struct mbuf *m = *m0;
1089 struct pf_rule *r;
1090 struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1091 int off;
1092 struct ip6_ext ext;
1093 struct ip6_opt opt;
1094 struct ip6_opt_jumbo jumbo;
1095 struct ip6_frag frag;
1096 u_int32_t jumbolen = 0, plen;
1097 u_int16_t fragoff = 0;
1098 int optend;
1099 int ooff;
1100 u_int8_t proto;
1101 int terminal;
1102
1103 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1104 while (r != NULL) {
1105 r->evaluations++;
1106 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1107 r = r->skip[PF_SKIP_IFP].ptr;
1108 else if (r->direction && r->direction != dir)
1109 r = r->skip[PF_SKIP_DIR].ptr;
1110 else if (r->af && r->af != AF_INET6)
1111 r = r->skip[PF_SKIP_AF].ptr;
1112 #if 0 /* header chain! */
1113 else if (r->proto && r->proto != h->ip6_nxt)
1114 r = r->skip[PF_SKIP_PROTO].ptr;
1115 #endif
1116 else if (PF_MISMATCHAW(&r->src.addr,
1117 (struct pf_addr *)&h->ip6_src, AF_INET6,
1118 r->src.neg, kif))
1119 r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1120 else if (PF_MISMATCHAW(&r->dst.addr,
1121 (struct pf_addr *)&h->ip6_dst, AF_INET6,
1122 r->dst.neg, NULL))
1123 r = r->skip[PF_SKIP_DST_ADDR].ptr;
1124 else
1125 break;
1126 }
1127
1128 if (r == NULL || r->action == PF_NOSCRUB)
1129 return (PF_PASS);
1130 else {
1131 r->packets[dir == PF_OUT]++;
1132 r->bytes[dir == PF_OUT] += pd->tot_len;
1133 }
1134
1135 /* Check for illegal packets */
1136 if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len)
1137 goto drop;
1138
1139 off = sizeof(struct ip6_hdr);
1140 proto = h->ip6_nxt;
1141 terminal = 0;
1142 do {
1143 switch (proto) {
1144 case IPPROTO_FRAGMENT:
1145 goto fragment;
1146 break;
1147 case IPPROTO_AH:
1148 case IPPROTO_ROUTING:
1149 case IPPROTO_DSTOPTS:
1150 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1151 NULL, AF_INET6))
1152 goto shortpkt;
1153 if (proto == IPPROTO_AH)
1154 off += (ext.ip6e_len + 2) * 4;
1155 else
1156 off += (ext.ip6e_len + 1) * 8;
1157 proto = ext.ip6e_nxt;
1158 break;
1159 case IPPROTO_HOPOPTS:
1160 if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
1161 NULL, AF_INET6))
1162 goto shortpkt;
1163 optend = off + (ext.ip6e_len + 1) * 8;
1164 ooff = off + sizeof(ext);
1165 do {
1166 if (!pf_pull_hdr(m, ooff, &opt.ip6o_type,
1167 sizeof(opt.ip6o_type), NULL, NULL,
1168 AF_INET6))
1169 goto shortpkt;
1170 if (opt.ip6o_type == IP6OPT_PAD1) {
1171 ooff++;
1172 continue;
1173 }
1174 if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt),
1175 NULL, NULL, AF_INET6))
1176 goto shortpkt;
1177 if (ooff + sizeof(opt) + opt.ip6o_len > optend)
1178 goto drop;
1179 switch (opt.ip6o_type) {
1180 case IP6OPT_JUMBO:
1181 if (h->ip6_plen != 0)
1182 goto drop;
1183 if (!pf_pull_hdr(m, ooff, &jumbo,
1184 sizeof(jumbo), NULL, NULL,
1185 AF_INET6))
1186 goto shortpkt;
1187 memcpy(&jumbolen, jumbo.ip6oj_jumbo_len,
1188 sizeof(jumbolen));
1189 jumbolen = ntohl(jumbolen);
1190 if (jumbolen <= IPV6_MAXPACKET)
1191 goto drop;
1192 if (sizeof(struct ip6_hdr) + jumbolen !=
1193 m->m_pkthdr.len)
1194 goto drop;
1195 break;
1196 default:
1197 break;
1198 }
1199 ooff += sizeof(opt) + opt.ip6o_len;
1200 } while (ooff < optend);
1201
1202 off = optend;
1203 proto = ext.ip6e_nxt;
1204 break;
1205 default:
1206 terminal = 1;
1207 break;
1208 }
1209 } while (!terminal);
1210
1211 /* jumbo payload option must be present, or plen > 0 */
1212 if (ntohs(h->ip6_plen) == 0)
1213 plen = jumbolen;
1214 else
1215 plen = ntohs(h->ip6_plen);
1216 if (plen == 0)
1217 goto drop;
1218 if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
1219 goto shortpkt;
1220
1221 /* Enforce a minimum ttl, may cause endless packet loops */
1222 if (r->min_ttl && h->ip6_hlim < r->min_ttl)
1223 h->ip6_hlim = r->min_ttl;
1224
1225 return (PF_PASS);
1226
1227 fragment:
1228 if (ntohs(h->ip6_plen) == 0 || jumbolen)
1229 goto drop;
1230 plen = ntohs(h->ip6_plen);
1231
1232 if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6))
1233 goto shortpkt;
1234 fragoff = ntohs(frag.ip6f_offlg & IP6F_OFF_MASK);
1235 if (fragoff + (plen - off - sizeof(frag)) > IPV6_MAXPACKET)
1236 goto badfrag;
1237
1238 /* do something about it */
1239 /* remember to set pd->flags |= PFDESC_IP_REAS */
1240 return (PF_PASS);
1241
1242 shortpkt:
1243 REASON_SET(reason, PFRES_SHORT);
1244 if (r != NULL && r->log)
1245 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL, pd);
1246 return (PF_DROP);
1247
1248 drop:
1249 REASON_SET(reason, PFRES_NORM);
1250 if (r != NULL && r->log)
1251 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL, pd);
1252 return (PF_DROP);
1253
1254 badfrag:
1255 REASON_SET(reason, PFRES_FRAG);
1256 if (r != NULL && r->log)
1257 PFLOG_PACKET(kif, h, m, AF_INET6, dir, *reason, r, NULL, NULL, pd);
1258 return (PF_DROP);
1259 }
1260 #endif /* INET6 */
1261
1262 int
1263 pf_normalize_tcp(int dir, struct pfi_kif *kif, struct mbuf *m,
1264 int ipoff, int off, void *h, struct pf_pdesc *pd)
1265 {
1266 struct pf_rule *r, *rm = NULL;
1267 struct tcphdr *th = pd->hdr.tcp;
1268 int rewrite = 0;
1269 u_short reason;
1270 u_int8_t flags;
1271 sa_family_t af = pd->af;
1272
1273 r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1274 while (r != NULL) {
1275 r->evaluations++;
1276 if (pfi_kif_match(r->kif, kif) == r->ifnot)
1277 r = r->skip[PF_SKIP_IFP].ptr;
1278 else if (r->direction && r->direction != dir)
1279 r = r->skip[PF_SKIP_DIR].ptr;
1280 else if (r->af && r->af != af)
1281 r = r->skip[PF_SKIP_AF].ptr;
1282 else if (r->proto && r->proto != pd->proto)
1283 r = r->skip[PF_SKIP_PROTO].ptr;
1284 else if (PF_MISMATCHAW(&r->src.addr, pd->src, af,
1285 r->src.neg, kif))
1286 r = r->skip[PF_SKIP_SRC_ADDR].ptr;
1287 else if (r->src.port_op && !pf_match_port(r->src.port_op,
1288 r->src.port[0], r->src.port[1], th->th_sport))
1289 r = r->skip[PF_SKIP_SRC_PORT].ptr;
1290 else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af,
1291 r->dst.neg, NULL))
1292 r = r->skip[PF_SKIP_DST_ADDR].ptr;
1293 else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
1294 r->dst.port[0], r->dst.port[1], th->th_dport))
1295 r = r->skip[PF_SKIP_DST_PORT].ptr;
1296 else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match(
1297 pf_osfp_fingerprint(pd, m, off, th),
1298 r->os_fingerprint))
1299 r = TAILQ_NEXT(r, entries);
1300 else {
1301 rm = r;
1302 break;
1303 }
1304 }
1305
1306 if (rm == NULL || rm->action == PF_NOSCRUB)
1307 return (PF_PASS);
1308 else {
1309 r->packets[dir == PF_OUT]++;
1310 r->bytes[dir == PF_OUT] += pd->tot_len;
1311 }
1312
1313 if (rm->rule_flag & PFRULE_REASSEMBLE_TCP)
1314 pd->flags |= PFDESC_TCP_NORM;
1315
1316 flags = th->th_flags;
1317 if (flags & TH_SYN) {
1318 /* Illegal packet */
1319 if (flags & TH_RST)
1320 goto tcp_drop;
1321
1322 if (flags & TH_FIN)
1323 flags &= ~TH_FIN;
1324 } else {
1325 /* Illegal packet */
1326 if (!(flags & (TH_ACK|TH_RST)))
1327 goto tcp_drop;
1328 }
1329
1330 if (!(flags & TH_ACK)) {
1331 /* These flags are only valid if ACK is set */
1332 if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG))
1333 goto tcp_drop;
1334 }
1335
1336 /* Check for illegal header length */
1337 if (th->th_off < (sizeof(struct tcphdr) >> 2))
1338 goto tcp_drop;
1339
1340 /* If flags changed, or reserved data set, then adjust */
1341 if (flags != th->th_flags || th->th_x2 != 0) {
1342 u_int16_t ov, nv;
1343
1344 ov = *(u_int16_t *)(&th->th_ack + 1);
1345 th->th_flags = flags;
1346 th->th_x2 = 0;
1347 nv = *(u_int16_t *)(&th->th_ack + 1);
1348
1349 th->th_sum = pf_cksum_fixup(th->th_sum, ov, nv, 0);
1350 rewrite = 1;
1351 }
1352
1353 /* Remove urgent pointer, if TH_URG is not set */
1354 if (!(flags & TH_URG) && th->th_urp) {
1355 th->th_sum = pf_cksum_fixup(th->th_sum, th->th_urp, 0, 0);
1356 th->th_urp = 0;
1357 rewrite = 1;
1358 }
1359
1360 /* Process options */
1361 if (r->max_mss && pf_normalize_tcpopt(r, m, th, off))
1362 rewrite = 1;
1363
1364 /* copy back packet headers if we sanitized */
1365 if (rewrite)
1366 m_copyback(m, off, sizeof(*th), th);
1367
1368 return (PF_PASS);
1369
1370 tcp_drop:
1371 REASON_SET(&reason, PFRES_NORM);
1372 if (rm != NULL && r->log)
1373 PFLOG_PACKET(kif, h, m, AF_INET, dir, reason, r, NULL, NULL, pd);
1374 return (PF_DROP);
1375 }
1376
1377 int
1378 pf_normalize_tcp_init(struct mbuf *m, int off, struct pf_pdesc *pd,
1379 struct tcphdr *th, struct pf_state_peer *src,
1380 struct pf_state_peer *dst)
1381 {
1382 u_int32_t tsval, tsecr;
1383 u_int8_t hdr[60];
1384 u_int8_t *opt;
1385
1386 KASSERT(src->scrub == NULL);
1387
1388 src->scrub = pool_get(&pf_state_scrub_pl, PR_NOWAIT);
1389 if (src->scrub == NULL)
1390 return (1);
1391 bzero(src->scrub, sizeof(*src->scrub));
1392
1393 switch (pd->af) {
1394 #ifdef INET
1395 case AF_INET: {
1396 struct ip *h = mtod(m, struct ip *);
1397 src->scrub->pfss_ttl = h->ip_ttl;
1398 break;
1399 }
1400 #endif /* INET */
1401 #ifdef INET6
1402 case AF_INET6: {
1403 struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1404 src->scrub->pfss_ttl = h->ip6_hlim;
1405 break;
1406 }
1407 #endif /* INET6 */
1408 }
1409
1410
1411 /*
1412 * All normalizations below are only begun if we see the start of
1413 * the connections. They must all set an enabled bit in pfss_flags
1414 */
1415 if ((th->th_flags & TH_SYN) == 0)
1416 return (0);
1417
1418
1419 if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub &&
1420 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1421 /* Diddle with TCP options */
1422 int hlen;
1423 opt = hdr + sizeof(struct tcphdr);
1424 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1425 while (hlen >= TCPOLEN_TIMESTAMP) {
1426 switch (*opt) {
1427 case TCPOPT_EOL: /* FALLTHROUGH */
1428 case TCPOPT_NOP:
1429 opt++;
1430 hlen--;
1431 break;
1432 case TCPOPT_TIMESTAMP:
1433 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1434 src->scrub->pfss_flags |=
1435 PFSS_TIMESTAMP;
1436 src->scrub->pfss_ts_mod =
1437 htonl(arc4random());
1438
1439 /* note PFSS_PAWS not set yet */
1440 memcpy(&tsval, &opt[2],
1441 sizeof(u_int32_t));
1442 memcpy(&tsecr, &opt[6],
1443 sizeof(u_int32_t));
1444 src->scrub->pfss_tsval0 = ntohl(tsval);
1445 src->scrub->pfss_tsval = ntohl(tsval);
1446 src->scrub->pfss_tsecr = ntohl(tsecr);
1447 getmicrouptime(&src->scrub->pfss_last);
1448 }
1449 /* FALLTHROUGH */
1450 default:
1451 hlen -= MAX(opt[1], 2);
1452 opt += MAX(opt[1], 2);
1453 break;
1454 }
1455 }
1456 }
1457
1458 return (0);
1459 }
1460
1461 void
1462 pf_normalize_tcp_cleanup(struct pf_state *state)
1463 {
1464 if (state->src.scrub)
1465 pool_put(&pf_state_scrub_pl, state->src.scrub);
1466 if (state->dst.scrub)
1467 pool_put(&pf_state_scrub_pl, state->dst.scrub);
1468
1469 /* Someday... flush the TCP segment reassembly descriptors. */
1470 }
1471
1472 int
1473 pf_normalize_tcp_stateful(struct mbuf *m, int off, struct pf_pdesc *pd,
1474 u_short *reason, struct tcphdr *th, struct pf_state *state,
1475 struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback)
1476 {
1477 struct timeval uptime;
1478 u_int32_t tsval, tsecr;
1479 u_int tsval_from_last;
1480 u_int8_t hdr[60];
1481 u_int8_t *opt;
1482 int copyback = 0;
1483 int got_ts = 0;
1484
1485 KASSERT(src->scrub || dst->scrub);
1486
1487 /*
1488 * Enforce the minimum TTL seen for this connection. Negate a common
1489 * technique to evade an intrusion detection system and confuse
1490 * firewall state code.
1491 */
1492 switch (pd->af) {
1493 #ifdef INET
1494 case AF_INET: {
1495 if (src->scrub) {
1496 struct ip *h = mtod(m, struct ip *);
1497 if (h->ip_ttl > src->scrub->pfss_ttl)
1498 src->scrub->pfss_ttl = h->ip_ttl;
1499 h->ip_ttl = src->scrub->pfss_ttl;
1500 }
1501 break;
1502 }
1503 #endif /* INET */
1504 #ifdef INET6
1505 case AF_INET6: {
1506 if (src->scrub) {
1507 struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
1508 if (h->ip6_hlim > src->scrub->pfss_ttl)
1509 src->scrub->pfss_ttl = h->ip6_hlim;
1510 h->ip6_hlim = src->scrub->pfss_ttl;
1511 }
1512 break;
1513 }
1514 #endif /* INET6 */
1515 }
1516
1517 if (th->th_off > (sizeof(struct tcphdr) >> 2) &&
1518 ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) ||
1519 (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) &&
1520 pf_pull_hdr(m, off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1521 /* Diddle with TCP options */
1522 int hlen;
1523 opt = hdr + sizeof(struct tcphdr);
1524 hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1525 while (hlen >= TCPOLEN_TIMESTAMP) {
1526 switch (*opt) {
1527 case TCPOPT_EOL: /* FALLTHROUGH */
1528 case TCPOPT_NOP:
1529 opt++;
1530 hlen--;
1531 break;
1532 case TCPOPT_TIMESTAMP:
1533 /* Modulate the timestamps. Can be used for
1534 * NAT detection, OS uptime determination or
1535 * reboot detection.
1536 */
1537
1538 if (got_ts) {
1539 /* Huh? Multiple timestamps!? */
1540 if (pf_status.debug >= PF_DEBUG_MISC) {
1541 DPFPRINTF(("multiple TS??"));
1542 pf_print_state(state);
1543 printf("\n");
1544 }
1545 REASON_SET(reason, PFRES_TS);
1546 return (PF_DROP);
1547 }
1548 if (opt[1] >= TCPOLEN_TIMESTAMP) {
1549 memcpy(&tsval, &opt[2],
1550 sizeof(u_int32_t));
1551 if (tsval && src->scrub &&
1552 (src->scrub->pfss_flags &
1553 PFSS_TIMESTAMP)) {
1554 tsval = ntohl(tsval);
1555 pf_change_a(&opt[2],
1556 &th->th_sum,
1557 htonl(tsval +
1558 src->scrub->pfss_ts_mod),
1559 0);
1560 copyback = 1;
1561 }
1562
1563 /* Modulate TS reply iff valid (!0) */
1564 memcpy(&tsecr, &opt[6],
1565 sizeof(u_int32_t));
1566 if (tsecr && dst->scrub &&
1567 (dst->scrub->pfss_flags &
1568 PFSS_TIMESTAMP)) {
1569 tsecr = ntohl(tsecr)
1570 - dst->scrub->pfss_ts_mod;
1571 pf_change_a(&opt[6],
1572 &th->th_sum, htonl(tsecr),
1573 0);
1574 copyback = 1;
1575 }
1576 got_ts = 1;
1577 }
1578 /* FALLTHROUGH */
1579 default:
1580 hlen -= MAX(opt[1], 2);
1581 opt += MAX(opt[1], 2);
1582 break;
1583 }
1584 }
1585 if (copyback) {
1586 /* Copyback the options, caller copys back header */
1587 *writeback = 1;
1588 m_copyback(m, off + sizeof(struct tcphdr),
1589 (th->th_off << 2) - sizeof(struct tcphdr), hdr +
1590 sizeof(struct tcphdr));
1591 }
1592 }
1593
1594
1595 /*
1596 * Must invalidate PAWS checks on connections idle for too long.
1597 * The fastest allowed timestamp clock is 1ms. That turns out to
1598 * be about 24 days before it wraps. XXX Right now our lowerbound
1599 * TS echo check only works for the first 12 days of a connection
1600 * when the TS has exhausted half its 32bit space
1601 */
1602 #define TS_MAX_IDLE (24*24*60*60)
1603 #define TS_MAX_CONN (12*24*60*60) /* XXX remove when better tsecr check */
1604
1605 getmicrouptime(&uptime);
1606 if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) &&
1607 (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE ||
1608 time_second - state->creation > TS_MAX_CONN)) {
1609 if (pf_status.debug >= PF_DEBUG_MISC) {
1610 DPFPRINTF(("src idled out of PAWS\n"));
1611 pf_print_state(state);
1612 printf("\n");
1613 }
1614 src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS)
1615 | PFSS_PAWS_IDLED;
1616 }
1617 if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) &&
1618 uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) {
1619 if (pf_status.debug >= PF_DEBUG_MISC) {
1620 DPFPRINTF(("dst idled out of PAWS\n"));
1621 pf_print_state(state);
1622 printf("\n");
1623 }
1624 dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS)
1625 | PFSS_PAWS_IDLED;
1626 }
1627
1628 if (got_ts && src->scrub && dst->scrub &&
1629 (src->scrub->pfss_flags & PFSS_PAWS) &&
1630 (dst->scrub->pfss_flags & PFSS_PAWS)) {
1631 /* Validate that the timestamps are "in-window".
1632 * RFC1323 describes TCP Timestamp options that allow
1633 * measurement of RTT (round trip time) and PAWS
1634 * (protection against wrapped sequence numbers). PAWS
1635 * gives us a set of rules for rejecting packets on
1636 * long fat pipes (packets that were somehow delayed
1637 * in transit longer than the time it took to send the
1638 * full TCP sequence space of 4Gb). We can use these
1639 * rules and infer a few others that will let us treat
1640 * the 32bit timestamp and the 32bit echoed timestamp
1641 * as sequence numbers to prevent a blind attacker from
1642 * inserting packets into a connection.
1643 *
1644 * RFC1323 tells us:
1645 * - The timestamp on this packet must be greater than
1646 * or equal to the last value echoed by the other
1647 * endpoint. The RFC says those will be discarded
1648 * since it is a dup that has already been acked.
1649 * This gives us a lowerbound on the timestamp.
1650 * timestamp >= other last echoed timestamp
1651 * - The timestamp will be less than or equal to
1652 * the last timestamp plus the time between the
1653 * last packet and now. The RFC defines the max
1654 * clock rate as 1ms. We will allow clocks to be
1655 * up to 10% fast and will allow a total difference
1656 * or 30 seconds due to a route change. And this
1657 * gives us an upperbound on the timestamp.
1658 * timestamp <= last timestamp + max ticks
1659 * We have to be careful here. Windows will send an
1660 * initial timestamp of zero and then initialize it
1661 * to a random value after the 3whs; presumably to
1662 * avoid a DoS by having to call an expensive RNG
1663 * during a SYN flood. Proof MS has at least one
1664 * good security geek.
1665 *
1666 * - The TCP timestamp option must also echo the other
1667 * endpoints timestamp. The timestamp echoed is the
1668 * one carried on the earliest unacknowledged segment
1669 * on the left edge of the sequence window. The RFC
1670 * states that the host will reject any echoed
1671 * timestamps that were larger than any ever sent.
1672 * This gives us an upperbound on the TS echo.
1673 * tescr <= largest_tsval
1674 * - The lowerbound on the TS echo is a little more
1675 * tricky to determine. The other endpoint's echoed
1676 * values will not decrease. But there may be
1677 * network conditions that re-order packets and
1678 * cause our view of them to decrease. For now the
1679 * only lowerbound we can safely determine is that
1680 * the TS echo will never be less than the original
1681 * TS. XXX There is probably a better lowerbound.
1682 * Remove TS_MAX_CONN with better lowerbound check.
1683 * tescr >= other original TS
1684 *
1685 * It is also important to note that the fastest
1686 * timestamp clock of 1ms will wrap its 32bit space in
1687 * 24 days. So we just disable TS checking after 24
1688 * days of idle time. We actually must use a 12d
1689 * connection limit until we can come up with a better
1690 * lowerbound to the TS echo check.
1691 */
1692 struct timeval delta_ts;
1693 int ts_fudge;
1694
1695
1696 /*
1697 * PFTM_TS_DIFF is how many seconds of leeway to allow
1698 * a host's timestamp. This can happen if the previous
1699 * packet got delayed in transit for much longer than
1700 * this packet.
1701 */
1702 if ((ts_fudge = state->rule.ptr->timeout[PFTM_TS_DIFF]) == 0)
1703 ts_fudge = pf_default_rule.timeout[PFTM_TS_DIFF];
1704
1705
1706 /* Calculate max ticks since the last timestamp */
1707 #define TS_MAXFREQ 1100 /* RFC max TS freq of 1 kHz + 10% skew */
1708 #define TS_MICROSECS 1000000 /* microseconds per second */
1709 timersub(&uptime, &src->scrub->pfss_last, &delta_ts);
1710 tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ;
1711 tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ);
1712
1713
1714 if ((src->state >= TCPS_ESTABLISHED &&
1715 dst->state >= TCPS_ESTABLISHED) &&
1716 (SEQ_LT(tsval, dst->scrub->pfss_tsecr) ||
1717 SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) ||
1718 (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) ||
1719 SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) {
1720 /* Bad RFC1323 implementation or an insertion attack.
1721 *
1722 * - Solaris 2.6 and 2.7 are known to send another ACK
1723 * after the FIN,FIN|ACK,ACK closing that carries
1724 * an old timestamp.
1725 */
1726
1727 DPFPRINTF(("Timestamp failed %c%c%c%c\n",
1728 SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ',
1729 SEQ_GT(tsval, src->scrub->pfss_tsval +
1730 tsval_from_last) ? '1' : ' ',
1731 SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ',
1732 SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' '));
1733 DPFPRINTF((" tsval: %" PRIu32 " tsecr: %" PRIu32
1734 " +ticks: %" PRIu32 " idle: %"PRIx64"s %ums\n",
1735 tsval, tsecr, tsval_from_last, delta_ts.tv_sec,
1736 delta_ts.tv_usec / 1000U));
1737 DPFPRINTF((" src->tsval: %" PRIu32 " tsecr: %" PRIu32
1738 "\n",
1739 src->scrub->pfss_tsval, src->scrub->pfss_tsecr));
1740 DPFPRINTF((" dst->tsval: %" PRIu32 " tsecr: %" PRIu32
1741 " tsval0: %" PRIu32 "\n",
1742 dst->scrub->pfss_tsval,
1743 dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0));
1744 if (pf_status.debug >= PF_DEBUG_MISC) {
1745 pf_print_state(state);
1746 pf_print_flags(th->th_flags);
1747 printf("\n");
1748 }
1749 REASON_SET(reason, PFRES_TS);
1750 return (PF_DROP);
1751 }
1752
1753 /* XXX I'd really like to require tsecr but it's optional */
1754
1755 } else if (!got_ts && (th->th_flags & TH_RST) == 0 &&
1756 ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED)
1757 || pd->p_len > 0 || (th->th_flags & TH_SYN)) &&
1758 src->scrub && dst->scrub &&
1759 (src->scrub->pfss_flags & PFSS_PAWS) &&
1760 (dst->scrub->pfss_flags & PFSS_PAWS)) {
1761 /* Didn't send a timestamp. Timestamps aren't really useful
1762 * when:
1763 * - connection opening or closing (often not even sent).
1764 * but we must not let an attacker to put a FIN on a
1765 * data packet to sneak it through our ESTABLISHED check.
1766 * - on a TCP reset. RFC suggests not even looking at TS.
1767 * - on an empty ACK. The TS will not be echoed so it will
1768 * probably not help keep the RTT calculation in sync and
1769 * there isn't as much danger when the sequence numbers
1770 * got wrapped. So some stacks don't include TS on empty
1771 * ACKs :-(
1772 *
1773 * To minimize the disruption to mostly RFC1323 conformant
1774 * stacks, we will only require timestamps on data packets.
1775 *
1776 * And what do ya know, we cannot require timestamps on data
1777 * packets. There appear to be devices that do legitimate
1778 * TCP connection hijacking. There are HTTP devices that allow
1779 * a 3whs (with timestamps) and then buffer the HTTP request.
1780 * If the intermediate device has the HTTP response cache, it
1781 * will spoof the response but not bother timestamping its
1782 * packets. So we can look for the presence of a timestamp in
1783 * the first data packet and if there, require it in all future
1784 * packets.
1785 */
1786
1787 if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) {
1788 /*
1789 * Hey! Someone tried to sneak a packet in. Or the
1790 * stack changed its RFC1323 behavior?!?!
1791 */
1792 if (pf_status.debug >= PF_DEBUG_MISC) {
1793 DPFPRINTF(("Did not receive expected RFC1323 "
1794 "timestamp\n"));
1795 pf_print_state(state);
1796 pf_print_flags(th->th_flags);
1797 printf("\n");
1798 }
1799 REASON_SET(reason, PFRES_TS);
1800 return (PF_DROP);
1801 }
1802 }
1803
1804
1805 /*
1806 * We will note if a host sends his data packets with or without
1807 * timestamps. And require all data packets to contain a timestamp
1808 * if the first does. PAWS implicitly requires that all data packets be
1809 * timestamped. But I think there are middle-man devices that hijack
1810 * TCP streams immediately after the 3whs and don't timestamp their
1811 * packets (seen in a WWW accelerator or cache).
1812 */
1813 if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags &
1814 (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) {
1815 if (got_ts)
1816 src->scrub->pfss_flags |= PFSS_DATA_TS;
1817 else {
1818 src->scrub->pfss_flags |= PFSS_DATA_NOTS;
1819 if (pf_status.debug >= PF_DEBUG_MISC && dst->scrub &&
1820 (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) {
1821 /* Don't warn if other host rejected RFC1323 */
1822 DPFPRINTF(("Broken RFC1323 stack did not "
1823 "timestamp data packet. Disabled PAWS "
1824 "security.\n"));
1825 pf_print_state(state);
1826 pf_print_flags(th->th_flags);
1827 printf("\n");
1828 }
1829 }
1830 }
1831
1832
1833 /*
1834 * Update PAWS values
1835 */
1836 if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags &
1837 (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) {
1838 getmicrouptime(&src->scrub->pfss_last);
1839 if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) ||
1840 (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1841 src->scrub->pfss_tsval = tsval;
1842
1843 if (tsecr) {
1844 if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) ||
1845 (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1846 src->scrub->pfss_tsecr = tsecr;
1847
1848 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 &&
1849 (SEQ_LT(tsval, src->scrub->pfss_tsval0) ||
1850 src->scrub->pfss_tsval0 == 0)) {
1851 /* tsval0 MUST be the lowest timestamp */
1852 src->scrub->pfss_tsval0 = tsval;
1853 }
1854
1855 /* Only fully initialized after a TS gets echoed */
1856 if ((src->scrub->pfss_flags & PFSS_PAWS) == 0)
1857 src->scrub->pfss_flags |= PFSS_PAWS;
1858 }
1859 }
1860
1861 /* I have a dream.... TCP segment reassembly.... */
1862 return (0);
1863 }
1864
1865 int
1866 pf_normalize_tcpopt(struct pf_rule *r, struct mbuf *m, struct tcphdr *th,
1867 int off)
1868 {
1869 u_int16_t *mss;
1870 int thoff;
1871 int opt, cnt, optlen = 0;
1872 int rewrite = 0;
1873 u_char *optp;
1874
1875 thoff = th->th_off << 2;
1876 cnt = thoff - sizeof(struct tcphdr);
1877 optp = mtod(m, u_char *) + off + sizeof(struct tcphdr);
1878
1879 for (; cnt > 0; cnt -= optlen, optp += optlen) {
1880 opt = optp[0];
1881 if (opt == TCPOPT_EOL)
1882 break;
1883 if (opt == TCPOPT_NOP)
1884 optlen = 1;
1885 else {
1886 if (cnt < 2)
1887 break;
1888 optlen = optp[1];
1889 if (optlen < 2 || optlen > cnt)
1890 break;
1891 }
1892 switch (opt) {
1893 case TCPOPT_MAXSEG:
1894 mss = (u_int16_t *)(optp + 2);
1895 if ((ntohs(*mss)) > r->max_mss) {
1896 th->th_sum = pf_cksum_fixup(th->th_sum,
1897 *mss, htons(r->max_mss), 0);
1898 *mss = htons(r->max_mss);
1899 rewrite = 1;
1900 }
1901 break;
1902 default:
1903 break;
1904 }
1905 }
1906
1907 return (rewrite);
1908 }
NetBSD on the FriendlyARM MINI2440