xref: /freebsd/sys/netpfil/pf/pf_norm.c (revision c11d317a8bd60d93d3c3ced765071f468adacd69)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright 2001 Niels Provos <provos@citi.umich.edu>
5  * Copyright 2011-2018 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 #include "opt_inet.h"
33 #include "opt_inet6.h"
34 #include "opt_pf.h"
35 
36 #include <sys/param.h>
37 #include <sys/kernel.h>
38 #include <sys/lock.h>
39 #include <sys/mbuf.h>
40 #include <sys/mutex.h>
41 #include <sys/refcount.h>
42 #include <sys/socket.h>
43 
44 #include <net/if.h>
45 #include <net/if_var.h>
46 #include <net/vnet.h>
47 #include <net/pfvar.h>
48 #include <net/if_pflog.h>
49 
50 #include <netinet/in.h>
51 #include <netinet/ip.h>
52 #include <netinet/ip_var.h>
53 #include <netinet6/in6_var.h>
54 #include <netinet6/nd6.h>
55 #include <netinet6/ip6_var.h>
56 #include <netinet6/scope6_var.h>
57 #include <netinet/tcp.h>
58 #include <netinet/tcp_fsm.h>
59 #include <netinet/tcp_seq.h>
60 #include <netinet/sctp_constants.h>
61 #include <netinet/sctp_header.h>
62 
63 #ifdef INET6
64 #include <netinet/ip6.h>
65 #endif /* INET6 */
66 
67 struct pf_frent {
68 	TAILQ_ENTRY(pf_frent)	fr_next;
69 	struct mbuf	*fe_m;
70 	uint16_t	fe_hdrlen;	/* ipv4 header length with ip options
71 					   ipv6, extension, fragment header */
72 	uint16_t	fe_extoff;	/* last extension header offset or 0 */
73 	uint16_t	fe_len;		/* fragment length */
74 	uint16_t	fe_off;		/* fragment offset */
75 	uint16_t	fe_mff;		/* more fragment flag */
76 };
77 
78 struct pf_fragment_cmp {
79 	struct pf_addr	frc_src;
80 	struct pf_addr	frc_dst;
81 	uint32_t	frc_id;
82 	sa_family_t	frc_af;
83 	uint8_t		frc_proto;
84 };
85 
86 struct pf_fragment {
87 	struct pf_fragment_cmp	fr_key;
88 #define fr_src	fr_key.frc_src
89 #define fr_dst	fr_key.frc_dst
90 #define fr_id	fr_key.frc_id
91 #define fr_af	fr_key.frc_af
92 #define fr_proto	fr_key.frc_proto
93 
94 	/* pointers to queue element */
95 	struct pf_frent	*fr_firstoff[PF_FRAG_ENTRY_POINTS];
96 	/* count entries between pointers */
97 	uint8_t	fr_entries[PF_FRAG_ENTRY_POINTS];
98 	RB_ENTRY(pf_fragment) fr_entry;
99 	TAILQ_ENTRY(pf_fragment) frag_next;
100 	uint32_t	fr_timeout;
101 	TAILQ_HEAD(pf_fragq, pf_frent) fr_queue;
102 	uint16_t	fr_maxlen;	/* maximum length of single fragment */
103 	u_int16_t	fr_holes;	/* number of holes in the queue */
104 };
105 
106 VNET_DEFINE_STATIC(struct mtx, pf_frag_mtx);
107 #define V_pf_frag_mtx		VNET(pf_frag_mtx)
108 #define PF_FRAG_LOCK()		mtx_lock(&V_pf_frag_mtx)
109 #define PF_FRAG_UNLOCK()	mtx_unlock(&V_pf_frag_mtx)
110 #define PF_FRAG_ASSERT()	mtx_assert(&V_pf_frag_mtx, MA_OWNED)
111 
112 VNET_DEFINE(uma_zone_t, pf_state_scrub_z);	/* XXX: shared with pfsync */
113 
114 VNET_DEFINE_STATIC(uma_zone_t, pf_frent_z);
115 #define	V_pf_frent_z	VNET(pf_frent_z)
116 VNET_DEFINE_STATIC(uma_zone_t, pf_frag_z);
117 #define	V_pf_frag_z	VNET(pf_frag_z)
118 
119 TAILQ_HEAD(pf_fragqueue, pf_fragment);
120 TAILQ_HEAD(pf_cachequeue, pf_fragment);
121 VNET_DEFINE_STATIC(struct pf_fragqueue,	pf_fragqueue);
122 #define	V_pf_fragqueue			VNET(pf_fragqueue)
123 RB_HEAD(pf_frag_tree, pf_fragment);
124 VNET_DEFINE_STATIC(struct pf_frag_tree,	pf_frag_tree);
125 #define	V_pf_frag_tree			VNET(pf_frag_tree)
126 static int		 pf_frag_compare(struct pf_fragment *,
127 			    struct pf_fragment *);
128 static RB_PROTOTYPE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
129 static RB_GENERATE(pf_frag_tree, pf_fragment, fr_entry, pf_frag_compare);
130 
131 static void	pf_flush_fragments(void);
132 static void	pf_free_fragment(struct pf_fragment *);
133 
134 static struct pf_frent *pf_create_fragment(u_short *);
135 static int	pf_frent_holes(struct pf_frent *frent);
136 static struct pf_fragment *pf_find_fragment(struct pf_fragment_cmp *key,
137 		    struct pf_frag_tree *tree);
138 static inline int	pf_frent_index(struct pf_frent *);
139 static int	pf_frent_insert(struct pf_fragment *,
140 			    struct pf_frent *, struct pf_frent *);
141 void			pf_frent_remove(struct pf_fragment *,
142 			    struct pf_frent *);
143 struct pf_frent		*pf_frent_previous(struct pf_fragment *,
144 			    struct pf_frent *);
145 static struct pf_fragment *pf_fillup_fragment(struct pf_fragment_cmp *,
146 		    struct pf_frent *, u_short *);
147 static struct mbuf *pf_join_fragment(struct pf_fragment *);
148 #ifdef INET
149 static int	pf_reassemble(struct mbuf **, int, u_short *);
150 #endif	/* INET */
151 #ifdef INET6
152 static int	pf_reassemble6(struct mbuf **,
153 		    struct ip6_frag *, uint16_t, uint16_t, u_short *);
154 #endif	/* INET6 */
155 
156 #define	DPFPRINTF(x) do {				\
157 	if (V_pf_status.debug >= PF_DEBUG_MISC) {	\
158 		printf("%s: ", __func__);		\
159 		printf x ;				\
160 	}						\
161 } while(0)
162 
163 #ifdef INET
164 static void
pf_ip2key(struct ip * ip,int dir,struct pf_fragment_cmp * key)165 pf_ip2key(struct ip *ip, int dir, struct pf_fragment_cmp *key)
166 {
167 
168 	key->frc_src.v4 = ip->ip_src;
169 	key->frc_dst.v4 = ip->ip_dst;
170 	key->frc_af = AF_INET;
171 	key->frc_proto = ip->ip_p;
172 	key->frc_id = ip->ip_id;
173 }
174 #endif	/* INET */
175 
176 void
pf_normalize_init(void)177 pf_normalize_init(void)
178 {
179 
180 	V_pf_frag_z = uma_zcreate("pf frags", sizeof(struct pf_fragment),
181 	    NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
182 	V_pf_frent_z = uma_zcreate("pf frag entries", sizeof(struct pf_frent),
183 	    NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
184 	V_pf_state_scrub_z = uma_zcreate("pf state scrubs",
185 	    sizeof(struct pf_state_scrub),  NULL, NULL, NULL, NULL,
186 	    UMA_ALIGN_PTR, 0);
187 
188 	mtx_init(&V_pf_frag_mtx, "pf fragments", NULL, MTX_DEF);
189 
190 	V_pf_limits[PF_LIMIT_FRAGS].zone = V_pf_frent_z;
191 	V_pf_limits[PF_LIMIT_FRAGS].limit = PFFRAG_FRENT_HIWAT;
192 	uma_zone_set_max(V_pf_frent_z, PFFRAG_FRENT_HIWAT);
193 	uma_zone_set_warning(V_pf_frent_z, "PF frag entries limit reached");
194 
195 	TAILQ_INIT(&V_pf_fragqueue);
196 }
197 
198 void
pf_normalize_cleanup(void)199 pf_normalize_cleanup(void)
200 {
201 
202 	uma_zdestroy(V_pf_state_scrub_z);
203 	uma_zdestroy(V_pf_frent_z);
204 	uma_zdestroy(V_pf_frag_z);
205 
206 	mtx_destroy(&V_pf_frag_mtx);
207 }
208 
209 static int
pf_frag_compare(struct pf_fragment * a,struct pf_fragment * b)210 pf_frag_compare(struct pf_fragment *a, struct pf_fragment *b)
211 {
212 	int	diff;
213 
214 	if ((diff = a->fr_id - b->fr_id) != 0)
215 		return (diff);
216 	if ((diff = a->fr_proto - b->fr_proto) != 0)
217 		return (diff);
218 	if ((diff = a->fr_af - b->fr_af) != 0)
219 		return (diff);
220 	if ((diff = pf_addr_cmp(&a->fr_src, &b->fr_src, a->fr_af)) != 0)
221 		return (diff);
222 	if ((diff = pf_addr_cmp(&a->fr_dst, &b->fr_dst, a->fr_af)) != 0)
223 		return (diff);
224 	return (0);
225 }
226 
227 void
pf_purge_expired_fragments(void)228 pf_purge_expired_fragments(void)
229 {
230 	u_int32_t	expire = time_uptime -
231 			    V_pf_default_rule.timeout[PFTM_FRAG];
232 
233 	pf_purge_fragments(expire);
234 }
235 
236 void
pf_purge_fragments(uint32_t expire)237 pf_purge_fragments(uint32_t expire)
238 {
239 	struct pf_fragment	*frag;
240 
241 	PF_FRAG_LOCK();
242 	while ((frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue)) != NULL) {
243 		if (frag->fr_timeout > expire)
244 			break;
245 
246 		DPFPRINTF(("expiring %d(%p)\n", frag->fr_id, frag));
247 		pf_free_fragment(frag);
248 	}
249 
250 	PF_FRAG_UNLOCK();
251 }
252 
253 /*
254  * Try to flush old fragments to make space for new ones
255  */
256 static void
pf_flush_fragments(void)257 pf_flush_fragments(void)
258 {
259 	struct pf_fragment	*frag;
260 	int			 goal;
261 
262 	PF_FRAG_ASSERT();
263 
264 	goal = uma_zone_get_cur(V_pf_frent_z) * 9 / 10;
265 	DPFPRINTF(("trying to free %d frag entriess\n", goal));
266 	while (goal < uma_zone_get_cur(V_pf_frent_z)) {
267 		frag = TAILQ_LAST(&V_pf_fragqueue, pf_fragqueue);
268 		if (frag)
269 			pf_free_fragment(frag);
270 		else
271 			break;
272 	}
273 }
274 
275 /*
276  * Remove a fragment from the fragment queue, free its fragment entries,
277  * and free the fragment itself.
278  */
279 static void
pf_free_fragment(struct pf_fragment * frag)280 pf_free_fragment(struct pf_fragment *frag)
281 {
282 	struct pf_frent		*frent;
283 
284 	PF_FRAG_ASSERT();
285 
286 	RB_REMOVE(pf_frag_tree, &V_pf_frag_tree, frag);
287 	TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
288 
289 	/* Free all fragment entries */
290 	while ((frent = TAILQ_FIRST(&frag->fr_queue)) != NULL) {
291 		TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
292 
293 		m_freem(frent->fe_m);
294 		uma_zfree(V_pf_frent_z, frent);
295 	}
296 
297 	uma_zfree(V_pf_frag_z, frag);
298 }
299 
300 static struct pf_fragment *
pf_find_fragment(struct pf_fragment_cmp * key,struct pf_frag_tree * tree)301 pf_find_fragment(struct pf_fragment_cmp *key, struct pf_frag_tree *tree)
302 {
303 	struct pf_fragment	*frag;
304 
305 	PF_FRAG_ASSERT();
306 
307 	frag = RB_FIND(pf_frag_tree, tree, (struct pf_fragment *)key);
308 	if (frag != NULL) {
309 		TAILQ_REMOVE(&V_pf_fragqueue, frag, frag_next);
310 		TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
311 	}
312 
313 	return (frag);
314 }
315 
316 static struct pf_frent *
pf_create_fragment(u_short * reason)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 /*
337  * Calculate the additional holes that were created in the fragment
338  * queue by inserting this fragment.  A fragment in the middle
339  * creates one more hole by splitting.  For each connected side,
340  * it loses one hole.
341  * Fragment entry must be in the queue when calling this function.
342  */
343 static int
pf_frent_holes(struct pf_frent * frent)344 pf_frent_holes(struct pf_frent *frent)
345 {
346 	struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next);
347 	struct pf_frent *next = TAILQ_NEXT(frent, fr_next);
348 	int holes = 1;
349 
350 	if (prev == NULL) {
351 		if (frent->fe_off == 0)
352 			holes--;
353 	} else {
354 		KASSERT(frent->fe_off != 0, ("frent->fe_off != 0"));
355 		if (frent->fe_off == prev->fe_off + prev->fe_len)
356 			holes--;
357 	}
358 	if (next == NULL) {
359 		if (!frent->fe_mff)
360 			holes--;
361 	} else {
362 		KASSERT(frent->fe_mff, ("frent->fe_mff"));
363 		if (next->fe_off == frent->fe_off + frent->fe_len)
364 			holes--;
365 	}
366 	return holes;
367 }
368 
369 static inline int
pf_frent_index(struct pf_frent * frent)370 pf_frent_index(struct pf_frent *frent)
371 {
372 	/*
373 	 * We have an array of 16 entry points to the queue.  A full size
374 	 * 65535 octet IP packet can have 8192 fragments.  So the queue
375 	 * traversal length is at most 512 and at most 16 entry points are
376 	 * checked.  We need 128 additional bytes on a 64 bit architecture.
377 	 */
378 	CTASSERT(((u_int16_t)0xffff &~ 7) / (0x10000 / PF_FRAG_ENTRY_POINTS) ==
379 	    16 - 1);
380 	CTASSERT(((u_int16_t)0xffff >> 3) / PF_FRAG_ENTRY_POINTS == 512 - 1);
381 
382 	return frent->fe_off / (0x10000 / PF_FRAG_ENTRY_POINTS);
383 }
384 
385 static int
pf_frent_insert(struct pf_fragment * frag,struct pf_frent * frent,struct pf_frent * prev)386 pf_frent_insert(struct pf_fragment *frag, struct pf_frent *frent,
387     struct pf_frent *prev)
388 {
389 	int index;
390 
391 	CTASSERT(PF_FRAG_ENTRY_LIMIT <= 0xff);
392 
393 	/*
394 	 * A packet has at most 65536 octets.  With 16 entry points, each one
395 	 * spawns 4096 octets.  We limit these to 64 fragments each, which
396 	 * means on average every fragment must have at least 64 octets.
397 	 */
398 	index = pf_frent_index(frent);
399 	if (frag->fr_entries[index] >= PF_FRAG_ENTRY_LIMIT)
400 		return ENOBUFS;
401 	frag->fr_entries[index]++;
402 
403 	if (prev == NULL) {
404 		TAILQ_INSERT_HEAD(&frag->fr_queue, frent, fr_next);
405 	} else {
406 		KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off,
407 		    ("overlapping fragment"));
408 		TAILQ_INSERT_AFTER(&frag->fr_queue, prev, frent, fr_next);
409 	}
410 
411 	if (frag->fr_firstoff[index] == NULL) {
412 		KASSERT(prev == NULL || pf_frent_index(prev) < index,
413 		    ("prev == NULL || pf_frent_index(pref) < index"));
414 		frag->fr_firstoff[index] = frent;
415 	} else {
416 		if (frent->fe_off < frag->fr_firstoff[index]->fe_off) {
417 			KASSERT(prev == NULL || pf_frent_index(prev) < index,
418 			    ("prev == NULL || pf_frent_index(pref) < index"));
419 			frag->fr_firstoff[index] = frent;
420 		} else {
421 			KASSERT(prev != NULL, ("prev != NULL"));
422 			KASSERT(pf_frent_index(prev) == index,
423 			    ("pf_frent_index(prev) == index"));
424 		}
425 	}
426 
427 	frag->fr_holes += pf_frent_holes(frent);
428 
429 	return 0;
430 }
431 
432 void
pf_frent_remove(struct pf_fragment * frag,struct pf_frent * frent)433 pf_frent_remove(struct pf_fragment *frag, struct pf_frent *frent)
434 {
435 #ifdef INVARIANTS
436 	struct pf_frent *prev = TAILQ_PREV(frent, pf_fragq, fr_next);
437 #endif
438 	struct pf_frent *next = TAILQ_NEXT(frent, fr_next);
439 	int index;
440 
441 	frag->fr_holes -= pf_frent_holes(frent);
442 
443 	index = pf_frent_index(frent);
444 	KASSERT(frag->fr_firstoff[index] != NULL, ("frent not found"));
445 	if (frag->fr_firstoff[index]->fe_off == frent->fe_off) {
446 		if (next == NULL) {
447 			frag->fr_firstoff[index] = NULL;
448 		} else {
449 			KASSERT(frent->fe_off + frent->fe_len <= next->fe_off,
450 			    ("overlapping fragment"));
451 			if (pf_frent_index(next) == index) {
452 				frag->fr_firstoff[index] = next;
453 			} else {
454 				frag->fr_firstoff[index] = NULL;
455 			}
456 		}
457 	} else {
458 		KASSERT(frag->fr_firstoff[index]->fe_off < frent->fe_off,
459 		    ("frag->fr_firstoff[index]->fe_off < frent->fe_off"));
460 		KASSERT(prev != NULL, ("prev != NULL"));
461 		KASSERT(prev->fe_off + prev->fe_len <= frent->fe_off,
462 		    ("overlapping fragment"));
463 		KASSERT(pf_frent_index(prev) == index,
464 		    ("pf_frent_index(prev) == index"));
465 	}
466 
467 	TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
468 
469 	KASSERT(frag->fr_entries[index] > 0, ("No fragments remaining"));
470 	frag->fr_entries[index]--;
471 }
472 
473 struct pf_frent *
pf_frent_previous(struct pf_fragment * frag,struct pf_frent * frent)474 pf_frent_previous(struct pf_fragment *frag, struct pf_frent *frent)
475 {
476 	struct pf_frent *prev, *next;
477 	int index;
478 
479 	/*
480 	 * If there are no fragments after frag, take the final one.  Assume
481 	 * that the global queue is not empty.
482 	 */
483 	prev = TAILQ_LAST(&frag->fr_queue, pf_fragq);
484 	KASSERT(prev != NULL, ("prev != NULL"));
485 	if (prev->fe_off <= frent->fe_off)
486 		return prev;
487 	/*
488 	 * We want to find a fragment entry that is before frag, but still
489 	 * close to it.  Find the first fragment entry that is in the same
490 	 * entry point or in the first entry point after that.  As we have
491 	 * already checked that there are entries behind frag, this will
492 	 * succeed.
493 	 */
494 	for (index = pf_frent_index(frent); index < PF_FRAG_ENTRY_POINTS;
495 	    index++) {
496 		prev = frag->fr_firstoff[index];
497 		if (prev != NULL)
498 			break;
499 	}
500 	KASSERT(prev != NULL, ("prev != NULL"));
501 	/*
502 	 * In prev we may have a fragment from the same entry point that is
503 	 * before frent, or one that is just one position behind frent.
504 	 * In the latter case, we go back one step and have the predecessor.
505 	 * There may be none if the new fragment will be the first one.
506 	 */
507 	if (prev->fe_off > frent->fe_off) {
508 		prev = TAILQ_PREV(prev, pf_fragq, fr_next);
509 		if (prev == NULL)
510 			return NULL;
511 		KASSERT(prev->fe_off <= frent->fe_off,
512 		    ("prev->fe_off <= frent->fe_off"));
513 		return prev;
514 	}
515 	/*
516 	 * In prev is the first fragment of the entry point.  The offset
517 	 * of frag is behind it.  Find the closest previous fragment.
518 	 */
519 	for (next = TAILQ_NEXT(prev, fr_next); next != NULL;
520 	    next = TAILQ_NEXT(next, fr_next)) {
521 		if (next->fe_off > frent->fe_off)
522 			break;
523 		prev = next;
524 	}
525 	return prev;
526 }
527 
528 static struct pf_fragment *
pf_fillup_fragment(struct pf_fragment_cmp * key,struct pf_frent * frent,u_short * reason)529 pf_fillup_fragment(struct pf_fragment_cmp *key, struct pf_frent *frent,
530     u_short *reason)
531 {
532 	struct pf_frent		*after, *next, *prev;
533 	struct pf_fragment	*frag;
534 	uint16_t		total;
535 
536 	PF_FRAG_ASSERT();
537 
538 	/* No empty fragments. */
539 	if (frent->fe_len == 0) {
540 		DPFPRINTF(("bad fragment: len 0\n"));
541 		goto bad_fragment;
542 	}
543 
544 	/* All fragments are 8 byte aligned. */
545 	if (frent->fe_mff && (frent->fe_len & 0x7)) {
546 		DPFPRINTF(("bad fragment: mff and len %d\n", frent->fe_len));
547 		goto bad_fragment;
548 	}
549 
550 	/* Respect maximum length, IP_MAXPACKET == IPV6_MAXPACKET. */
551 	if (frent->fe_off + frent->fe_len > IP_MAXPACKET) {
552 		DPFPRINTF(("bad fragment: max packet %d\n",
553 		    frent->fe_off + frent->fe_len));
554 		goto bad_fragment;
555 	}
556 
557 	DPFPRINTF((key->frc_af == AF_INET ?
558 	    "reass frag %d @ %d-%d\n" : "reass frag %#08x @ %d-%d\n",
559 	    key->frc_id, frent->fe_off, frent->fe_off + frent->fe_len));
560 
561 	/* Fully buffer all of the fragments in this fragment queue. */
562 	frag = pf_find_fragment(key, &V_pf_frag_tree);
563 
564 	/* Create a new reassembly queue for this packet. */
565 	if (frag == NULL) {
566 		frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
567 		if (frag == NULL) {
568 			pf_flush_fragments();
569 			frag = uma_zalloc(V_pf_frag_z, M_NOWAIT);
570 			if (frag == NULL) {
571 				REASON_SET(reason, PFRES_MEMORY);
572 				goto drop_fragment;
573 			}
574 		}
575 
576 		*(struct pf_fragment_cmp *)frag = *key;
577 		memset(frag->fr_firstoff, 0, sizeof(frag->fr_firstoff));
578 		memset(frag->fr_entries, 0, sizeof(frag->fr_entries));
579 		frag->fr_timeout = time_uptime;
580 		TAILQ_INIT(&frag->fr_queue);
581 		frag->fr_maxlen = frent->fe_len;
582 		frag->fr_holes = 1;
583 
584 		RB_INSERT(pf_frag_tree, &V_pf_frag_tree, frag);
585 		TAILQ_INSERT_HEAD(&V_pf_fragqueue, frag, frag_next);
586 
587 		/* We do not have a previous fragment, cannot fail. */
588 		pf_frent_insert(frag, frent, NULL);
589 
590 		return (frag);
591 	}
592 
593 	KASSERT(!TAILQ_EMPTY(&frag->fr_queue), ("!TAILQ_EMPTY()->fr_queue"));
594 
595 	/* Remember maximum fragment len for refragmentation. */
596 	if (frent->fe_len > frag->fr_maxlen)
597 		frag->fr_maxlen = frent->fe_len;
598 
599 	/* Maximum data we have seen already. */
600 	total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
601 		TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
602 
603 	/* Non terminal fragments must have more fragments flag. */
604 	if (frent->fe_off + frent->fe_len < total && !frent->fe_mff)
605 		goto bad_fragment;
606 
607 	/* Check if we saw the last fragment already. */
608 	if (!TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_mff) {
609 		if (frent->fe_off + frent->fe_len > total ||
610 		    (frent->fe_off + frent->fe_len == total && frent->fe_mff))
611 			goto bad_fragment;
612 	} else {
613 		if (frent->fe_off + frent->fe_len == total && !frent->fe_mff)
614 			goto bad_fragment;
615 	}
616 
617 	/* Find neighbors for newly inserted fragment */
618 	prev = pf_frent_previous(frag, frent);
619 	if (prev == NULL) {
620 		after = TAILQ_FIRST(&frag->fr_queue);
621 		KASSERT(after != NULL, ("after != NULL"));
622 	} else {
623 		after = TAILQ_NEXT(prev, fr_next);
624 	}
625 
626 	if (prev != NULL && prev->fe_off + prev->fe_len > frent->fe_off) {
627 		uint16_t precut;
628 
629 		if (frag->fr_af == AF_INET6)
630 			goto free_fragment;
631 
632 		precut = prev->fe_off + prev->fe_len - frent->fe_off;
633 		if (precut >= frent->fe_len) {
634 			DPFPRINTF(("new frag overlapped\n"));
635 			goto drop_fragment;
636 		}
637 		DPFPRINTF(("frag head overlap %d\n", precut));
638 		m_adj(frent->fe_m, precut);
639 		frent->fe_off += precut;
640 		frent->fe_len -= precut;
641 	}
642 
643 	for (; after != NULL && frent->fe_off + frent->fe_len > after->fe_off;
644 	    after = next) {
645 		uint16_t aftercut;
646 
647 		aftercut = frent->fe_off + frent->fe_len - after->fe_off;
648 		if (aftercut < after->fe_len) {
649 			DPFPRINTF(("frag tail overlap %d", aftercut));
650 			m_adj(after->fe_m, aftercut);
651 			/* Fragment may switch queue as fe_off changes */
652 			pf_frent_remove(frag, after);
653 			after->fe_off += aftercut;
654 			after->fe_len -= aftercut;
655 			/* Insert into correct queue */
656 			if (pf_frent_insert(frag, after, prev)) {
657 				DPFPRINTF(("fragment requeue limit exceeded"));
658 				m_freem(after->fe_m);
659 				uma_zfree(V_pf_frent_z, after);
660 				/* There is not way to recover */
661 				goto free_fragment;
662 			}
663 			break;
664 		}
665 
666 		/* This fragment is completely overlapped, lose it. */
667 		DPFPRINTF(("old frag overlapped\n"));
668 		next = TAILQ_NEXT(after, fr_next);
669 		pf_frent_remove(frag, after);
670 		m_freem(after->fe_m);
671 		uma_zfree(V_pf_frent_z, after);
672 	}
673 
674 	/* If part of the queue gets too long, there is not way to recover. */
675 	if (pf_frent_insert(frag, frent, prev)) {
676 		DPFPRINTF(("fragment queue limit exceeded\n"));
677 		goto bad_fragment;
678 	}
679 
680 	return (frag);
681 
682 free_fragment:
683 	/*
684 	 * RFC 5722, Errata 3089:  When reassembling an IPv6 datagram, if one
685 	 * or more its constituent fragments is determined to be an overlapping
686 	 * fragment, the entire datagram (and any constituent fragments) MUST
687 	 * be silently discarded.
688 	 */
689 	DPFPRINTF(("flush overlapping fragments\n"));
690 	pf_free_fragment(frag);
691 
692 bad_fragment:
693 	REASON_SET(reason, PFRES_FRAG);
694 drop_fragment:
695 	uma_zfree(V_pf_frent_z, frent);
696 	return (NULL);
697 }
698 
699 static struct mbuf *
pf_join_fragment(struct pf_fragment * frag)700 pf_join_fragment(struct pf_fragment *frag)
701 {
702 	struct mbuf *m, *m2;
703 	struct pf_frent	*frent;
704 
705 	frent = TAILQ_FIRST(&frag->fr_queue);
706 	TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
707 
708 	m = frent->fe_m;
709 	m_adj(m, (frent->fe_hdrlen + frent->fe_len) - m->m_pkthdr.len);
710 	uma_zfree(V_pf_frent_z, frent);
711 	while ((frent = TAILQ_FIRST(&frag->fr_queue)) != NULL) {
712 		TAILQ_REMOVE(&frag->fr_queue, frent, fr_next);
713 
714 		m2 = frent->fe_m;
715 		/* Strip off ip header. */
716 		m_adj(m2, frent->fe_hdrlen);
717 		/* Strip off any trailing bytes. */
718 		m_adj(m2, frent->fe_len - m2->m_pkthdr.len);
719 
720 		uma_zfree(V_pf_frent_z, frent);
721 		m_cat(m, m2);
722 	}
723 
724 	/* Remove from fragment queue. */
725 	pf_free_fragment(frag);
726 
727 	return (m);
728 }
729 
730 #ifdef INET
731 static int
pf_reassemble(struct mbuf ** m0,int dir,u_short * reason)732 pf_reassemble(struct mbuf **m0, int dir, u_short *reason)
733 {
734 	struct mbuf		*m = *m0;
735 	struct ip		*ip = mtod(m, struct ip *);
736 	struct pf_frent		*frent;
737 	struct pf_fragment	*frag;
738 	struct m_tag		*mtag;
739 	struct pf_fragment_tag	*ftag;
740 	struct pf_fragment_cmp	key;
741 	uint16_t		total, hdrlen;
742 	uint32_t		 frag_id;
743 	uint16_t		 maxlen;
744 
745 	/* Get an entry for the fragment queue */
746 	if ((frent = pf_create_fragment(reason)) == NULL)
747 		return (PF_DROP);
748 
749 	frent->fe_m = m;
750 	frent->fe_hdrlen = ip->ip_hl << 2;
751 	frent->fe_extoff = 0;
752 	frent->fe_len = ntohs(ip->ip_len) - (ip->ip_hl << 2);
753 	frent->fe_off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3;
754 	frent->fe_mff = ntohs(ip->ip_off) & IP_MF;
755 
756 	pf_ip2key(ip, dir, &key);
757 
758 	if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL)
759 		return (PF_DROP);
760 
761 	/* The mbuf is part of the fragment entry, no direct free or access */
762 	m = *m0 = NULL;
763 
764 	if (frag->fr_holes) {
765 		DPFPRINTF(("frag %d, holes %d\n", frag->fr_id, frag->fr_holes));
766 		return (PF_PASS);  /* drop because *m0 is NULL, no error */
767 	}
768 
769 	/* We have all the data */
770 	frent = TAILQ_FIRST(&frag->fr_queue);
771 	KASSERT(frent != NULL, ("frent != NULL"));
772 	total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
773 		TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
774 	hdrlen = frent->fe_hdrlen;
775 
776 	maxlen = frag->fr_maxlen;
777 	frag_id = frag->fr_id;
778 	m = *m0 = pf_join_fragment(frag);
779 	frag = NULL;
780 
781 	if (m->m_flags & M_PKTHDR) {
782 		int plen = 0;
783 		for (m = *m0; m; m = m->m_next)
784 			plen += m->m_len;
785 		m = *m0;
786 		m->m_pkthdr.len = plen;
787 	}
788 
789 	if ((mtag = m_tag_get(PACKET_TAG_PF_REASSEMBLED,
790 	    sizeof(struct pf_fragment_tag), M_NOWAIT)) == NULL) {
791 		REASON_SET(reason, PFRES_SHORT);
792 		/* PF_DROP requires a valid mbuf *m0 in pf_test() */
793 		return (PF_DROP);
794 	}
795 	ftag = (struct pf_fragment_tag *)(mtag + 1);
796 	ftag->ft_hdrlen = hdrlen;
797 	ftag->ft_extoff = 0;
798 	ftag->ft_maxlen = maxlen;
799 	ftag->ft_id = frag_id;
800 	m_tag_prepend(m, mtag);
801 
802 	ip = mtod(m, struct ip *);
803 	ip->ip_sum = pf_cksum_fixup(ip->ip_sum, ip->ip_len,
804 	    htons(hdrlen + total), 0);
805 	ip->ip_len = htons(hdrlen + total);
806 	ip->ip_sum = pf_cksum_fixup(ip->ip_sum, ip->ip_off,
807 	    ip->ip_off & ~(IP_MF|IP_OFFMASK), 0);
808 	ip->ip_off &= ~(IP_MF|IP_OFFMASK);
809 
810 	if (hdrlen + total > IP_MAXPACKET) {
811 		DPFPRINTF(("drop: too big: %d\n", total));
812 		ip->ip_len = 0;
813 		REASON_SET(reason, PFRES_SHORT);
814 		/* PF_DROP requires a valid mbuf *m0 in pf_test() */
815 		return (PF_DROP);
816 	}
817 
818 	DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip->ip_len)));
819 	return (PF_PASS);
820 }
821 #endif	/* INET */
822 
823 #ifdef INET6
824 static int
pf_reassemble6(struct mbuf ** m0,struct ip6_frag * fraghdr,uint16_t hdrlen,uint16_t extoff,u_short * reason)825 pf_reassemble6(struct mbuf **m0, struct ip6_frag *fraghdr,
826     uint16_t hdrlen, uint16_t extoff, u_short *reason)
827 {
828 	struct mbuf		*m = *m0;
829 	struct ip6_hdr		*ip6 = mtod(m, struct ip6_hdr *);
830 	struct pf_frent		*frent;
831 	struct pf_fragment	*frag;
832 	struct pf_fragment_cmp	 key;
833 	struct m_tag		*mtag;
834 	struct pf_fragment_tag	*ftag;
835 	int			 off;
836 	uint32_t		 frag_id;
837 	uint16_t		 total, maxlen;
838 	uint8_t			 proto;
839 
840 	PF_FRAG_LOCK();
841 
842 	/* Get an entry for the fragment queue. */
843 	if ((frent = pf_create_fragment(reason)) == NULL) {
844 		PF_FRAG_UNLOCK();
845 		return (PF_DROP);
846 	}
847 
848 	frent->fe_m = m;
849 	frent->fe_hdrlen = hdrlen;
850 	frent->fe_extoff = extoff;
851 	frent->fe_len = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - hdrlen;
852 	frent->fe_off = ntohs(fraghdr->ip6f_offlg & IP6F_OFF_MASK);
853 	frent->fe_mff = fraghdr->ip6f_offlg & IP6F_MORE_FRAG;
854 
855 	key.frc_src.v6 = ip6->ip6_src;
856 	key.frc_dst.v6 = ip6->ip6_dst;
857 	key.frc_af = AF_INET6;
858 	/* Only the first fragment's protocol is relevant. */
859 	key.frc_proto = 0;
860 	key.frc_id = fraghdr->ip6f_ident;
861 
862 	if ((frag = pf_fillup_fragment(&key, frent, reason)) == NULL) {
863 		PF_FRAG_UNLOCK();
864 		return (PF_DROP);
865 	}
866 
867 	/* The mbuf is part of the fragment entry, no direct free or access. */
868 	m = *m0 = NULL;
869 
870 	if (frag->fr_holes) {
871 		DPFPRINTF(("frag %d, holes %d\n", frag->fr_id,
872 		    frag->fr_holes));
873 		PF_FRAG_UNLOCK();
874 		return (PF_PASS);  /* Drop because *m0 is NULL, no error. */
875 	}
876 
877 	/* We have all the data. */
878 	frent = TAILQ_FIRST(&frag->fr_queue);
879 	KASSERT(frent != NULL, ("frent != NULL"));
880 	extoff = frent->fe_extoff;
881 	maxlen = frag->fr_maxlen;
882 	frag_id = frag->fr_id;
883 	total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off +
884 		TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len;
885 	hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag);
886 
887 	m = *m0 = pf_join_fragment(frag);
888 	frag = NULL;
889 
890 	PF_FRAG_UNLOCK();
891 
892 	/* Take protocol from first fragment header. */
893 	m = m_getptr(m, hdrlen + offsetof(struct ip6_frag, ip6f_nxt), &off);
894 	KASSERT(m, ("%s: short mbuf chain", __func__));
895 	proto = *(mtod(m, uint8_t *) + off);
896 	m = *m0;
897 
898 	/* Delete frag6 header */
899 	if (ip6_deletefraghdr(m, hdrlen, M_NOWAIT) != 0)
900 		goto fail;
901 
902 	if (m->m_flags & M_PKTHDR) {
903 		int plen = 0;
904 		for (m = *m0; m; m = m->m_next)
905 			plen += m->m_len;
906 		m = *m0;
907 		m->m_pkthdr.len = plen;
908 	}
909 
910 	if ((mtag = m_tag_get(PACKET_TAG_PF_REASSEMBLED,
911 	    sizeof(struct pf_fragment_tag), M_NOWAIT)) == NULL)
912 		goto fail;
913 	ftag = (struct pf_fragment_tag *)(mtag + 1);
914 	ftag->ft_hdrlen = hdrlen;
915 	ftag->ft_extoff = extoff;
916 	ftag->ft_maxlen = maxlen;
917 	ftag->ft_id = frag_id;
918 	m_tag_prepend(m, mtag);
919 
920 	ip6 = mtod(m, struct ip6_hdr *);
921 	ip6->ip6_plen = htons(hdrlen - sizeof(struct ip6_hdr) + total);
922 	if (extoff) {
923 		/* Write protocol into next field of last extension header. */
924 		m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
925 		    &off);
926 		KASSERT(m, ("%s: short mbuf chain", __func__));
927 		*(mtod(m, char *) + off) = proto;
928 		m = *m0;
929 	} else
930 		ip6->ip6_nxt = proto;
931 
932 	if (hdrlen - sizeof(struct ip6_hdr) + total > IPV6_MAXPACKET) {
933 		DPFPRINTF(("drop: too big: %d\n", total));
934 		ip6->ip6_plen = 0;
935 		REASON_SET(reason, PFRES_SHORT);
936 		/* PF_DROP requires a valid mbuf *m0 in pf_test6(). */
937 		return (PF_DROP);
938 	}
939 
940 	DPFPRINTF(("complete: %p(%d)\n", m, ntohs(ip6->ip6_plen)));
941 	return (PF_PASS);
942 
943 fail:
944 	REASON_SET(reason, PFRES_MEMORY);
945 	/* PF_DROP requires a valid mbuf *m0 in pf_test6(), will free later. */
946 	return (PF_DROP);
947 }
948 #endif	/* INET6 */
949 
950 #ifdef INET6
951 int
pf_max_frag_size(struct mbuf * m)952 pf_max_frag_size(struct mbuf *m)
953 {
954 	struct m_tag *tag;
955 	struct pf_fragment_tag *ftag;
956 
957 	tag = m_tag_find(m, PACKET_TAG_PF_REASSEMBLED, NULL);
958 	if (tag == NULL)
959 		return (m->m_pkthdr.len);
960 
961 	ftag = (struct pf_fragment_tag *)(tag + 1);
962 
963 	return (ftag->ft_maxlen);
964 }
965 
966 int
pf_refragment6(struct ifnet * ifp,struct mbuf ** m0,struct m_tag * mtag,struct ifnet * rt,bool forward)967 pf_refragment6(struct ifnet *ifp, struct mbuf **m0, struct m_tag *mtag,
968     struct ifnet *rt, bool forward)
969 {
970 	struct mbuf		*m = *m0, *t;
971 	struct ip6_hdr		*hdr;
972 	struct pf_fragment_tag	*ftag = (struct pf_fragment_tag *)(mtag + 1);
973 	struct pf_pdesc		 pd;
974 	uint32_t		 frag_id;
975 	uint16_t		 hdrlen, extoff, maxlen;
976 	uint8_t			 proto;
977 	int			 error, action;
978 
979 	hdrlen = ftag->ft_hdrlen;
980 	extoff = ftag->ft_extoff;
981 	maxlen = ftag->ft_maxlen;
982 	frag_id = ftag->ft_id;
983 	m_tag_delete(m, mtag);
984 	mtag = NULL;
985 	ftag = NULL;
986 
987 	if (extoff) {
988 		int off;
989 
990 		/* Use protocol from next field of last extension header */
991 		m = m_getptr(m, extoff + offsetof(struct ip6_ext, ip6e_nxt),
992 		    &off);
993 		KASSERT((m != NULL), ("pf_refragment6: short mbuf chain"));
994 		proto = *(mtod(m, uint8_t *) + off);
995 		*(mtod(m, char *) + off) = IPPROTO_FRAGMENT;
996 		m = *m0;
997 	} else {
998 		hdr = mtod(m, struct ip6_hdr *);
999 		proto = hdr->ip6_nxt;
1000 		hdr->ip6_nxt = IPPROTO_FRAGMENT;
1001 	}
1002 
1003 	/* In case of link-local traffic we'll need a scope set. */
1004 	hdr = mtod(m, struct ip6_hdr *);
1005 
1006 	in6_setscope(&hdr->ip6_src, ifp, NULL);
1007 	in6_setscope(&hdr->ip6_dst, ifp, NULL);
1008 
1009 	/* The MTU must be a multiple of 8 bytes, or we risk doing the
1010 	 * fragmentation wrong. */
1011 	maxlen = maxlen & ~7;
1012 
1013 	/*
1014 	 * Maxlen may be less than 8 if there was only a single
1015 	 * fragment.  As it was fragmented before, add a fragment
1016 	 * header also for a single fragment.  If total or maxlen
1017 	 * is less than 8, ip6_fragment() will return EMSGSIZE and
1018 	 * we drop the packet.
1019 	 */
1020 	error = ip6_fragment(ifp, m, hdrlen, proto, maxlen, frag_id);
1021 	m = (*m0)->m_nextpkt;
1022 	(*m0)->m_nextpkt = NULL;
1023 	if (error == 0) {
1024 		/* The first mbuf contains the unfragmented packet. */
1025 		m_freem(*m0);
1026 		*m0 = NULL;
1027 		action = PF_PASS;
1028 	} else {
1029 		/* Drop expects an mbuf to free. */
1030 		DPFPRINTF(("refragment error %d\n", error));
1031 		action = PF_DROP;
1032 	}
1033 	for (; m; m = t) {
1034 		t = m->m_nextpkt;
1035 		m->m_nextpkt = NULL;
1036 		m->m_flags |= M_SKIP_FIREWALL;
1037 		memset(&pd, 0, sizeof(pd));
1038 		pd.pf_mtag = pf_find_mtag(m);
1039 		if (error != 0) {
1040 			m_freem(m);
1041 			continue;
1042 		}
1043 		if (rt != NULL) {
1044 			struct sockaddr_in6	dst;
1045 			hdr = mtod(m, struct ip6_hdr *);
1046 
1047 			bzero(&dst, sizeof(dst));
1048 			dst.sin6_family = AF_INET6;
1049 			dst.sin6_len = sizeof(dst);
1050 			dst.sin6_addr = hdr->ip6_dst;
1051 
1052 			nd6_output_ifp(rt, rt, m, &dst, NULL);
1053 		} else if (forward) {
1054 			MPASS(m->m_pkthdr.rcvif != NULL);
1055 			ip6_forward(m, 0);
1056 		} else {
1057 			(void)ip6_output(m, NULL, NULL, 0, NULL, NULL,
1058 			    NULL);
1059 		}
1060 	}
1061 
1062 	return (action);
1063 }
1064 #endif /* INET6 */
1065 
1066 #ifdef INET
1067 int
pf_normalize_ip(u_short * reason,struct pf_pdesc * pd)1068 pf_normalize_ip(u_short *reason, struct pf_pdesc *pd)
1069 {
1070 	struct pf_krule		*r;
1071 	struct ip		*h = mtod(pd->m, struct ip *);
1072 	int			 mff = (ntohs(h->ip_off) & IP_MF);
1073 	int			 hlen = h->ip_hl << 2;
1074 	u_int16_t		 fragoff = (ntohs(h->ip_off) & IP_OFFMASK) << 3;
1075 	u_int16_t		 max;
1076 	int			 ip_len;
1077 	int			 tag = -1;
1078 	int			 verdict;
1079 	bool			 scrub_compat;
1080 
1081 	PF_RULES_RASSERT();
1082 
1083 	r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1084 	/*
1085 	 * Check if there are any scrub rules, matching or not.
1086 	 * Lack of scrub rules means:
1087 	 *  - enforced packet normalization operation just like in OpenBSD
1088 	 *  - fragment reassembly depends on V_pf_status.reass
1089 	 * With scrub rules:
1090 	 *  - packet normalization is performed if there is a matching scrub rule
1091 	 *  - fragment reassembly is performed if the matching rule has no
1092 	 *    PFRULE_FRAGMENT_NOREASS flag
1093 	 */
1094 	scrub_compat = (r != NULL);
1095 	while (r != NULL) {
1096 		pf_counter_u64_add(&r->evaluations, 1);
1097 		if (pfi_kkif_match(r->kif, pd->kif) == r->ifnot)
1098 			r = r->skip[PF_SKIP_IFP];
1099 		else if (r->direction && r->direction != pd->dir)
1100 			r = r->skip[PF_SKIP_DIR];
1101 		else if (r->af && r->af != AF_INET)
1102 			r = r->skip[PF_SKIP_AF];
1103 		else if (r->proto && r->proto != h->ip_p)
1104 			r = r->skip[PF_SKIP_PROTO];
1105 		else if (PF_MISMATCHAW(&r->src.addr,
1106 		    (struct pf_addr *)&h->ip_src.s_addr, AF_INET,
1107 		    r->src.neg, pd->kif, M_GETFIB(pd->m)))
1108 			r = r->skip[PF_SKIP_SRC_ADDR];
1109 		else if (PF_MISMATCHAW(&r->dst.addr,
1110 		    (struct pf_addr *)&h->ip_dst.s_addr, AF_INET,
1111 		    r->dst.neg, NULL, M_GETFIB(pd->m)))
1112 			r = r->skip[PF_SKIP_DST_ADDR];
1113 		else if (r->match_tag && !pf_match_tag(pd->m, r, &tag,
1114 		    pd->pf_mtag ? pd->pf_mtag->tag : 0))
1115 			r = TAILQ_NEXT(r, entries);
1116 		else
1117 			break;
1118 	}
1119 
1120 	if (scrub_compat) {
1121 		/* With scrub rules present IPv4 normalization happens only
1122 		 * if one of rules has matched and it's not a "no scrub" rule */
1123 		if (r == NULL || r->action == PF_NOSCRUB)
1124 			return (PF_PASS);
1125 
1126 		pf_counter_u64_critical_enter();
1127 		pf_counter_u64_add_protected(&r->packets[pd->dir == PF_OUT], 1);
1128 		pf_counter_u64_add_protected(&r->bytes[pd->dir == PF_OUT], pd->tot_len);
1129 		pf_counter_u64_critical_exit();
1130 		pf_rule_to_actions(r, &pd->act);
1131 	}
1132 
1133 	/* Check for illegal packets */
1134 	if (hlen < (int)sizeof(struct ip)) {
1135 		REASON_SET(reason, PFRES_NORM);
1136 		goto drop;
1137 	}
1138 
1139 	if (hlen > ntohs(h->ip_len)) {
1140 		REASON_SET(reason, PFRES_NORM);
1141 		goto drop;
1142 	}
1143 
1144 	/* Clear IP_DF if the rule uses the no-df option or we're in no-df mode */
1145 	if (((!scrub_compat && V_pf_status.reass & PF_REASS_NODF) ||
1146 	    (r != NULL && r->rule_flag & PFRULE_NODF)) &&
1147 	    (h->ip_off & htons(IP_DF))
1148 	) {
1149 		u_int16_t ip_off = h->ip_off;
1150 
1151 		h->ip_off &= htons(~IP_DF);
1152 		h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1153 	}
1154 
1155 	/* We will need other tests here */
1156 	if (!fragoff && !mff)
1157 		goto no_fragment;
1158 
1159 	/* We're dealing with a fragment now. Don't allow fragments
1160 	 * with IP_DF to enter the cache. If the flag was cleared by
1161 	 * no-df above, fine. Otherwise drop it.
1162 	 */
1163 	if (h->ip_off & htons(IP_DF)) {
1164 		DPFPRINTF(("IP_DF\n"));
1165 		goto bad;
1166 	}
1167 
1168 	ip_len = ntohs(h->ip_len) - hlen;
1169 
1170 	/* All fragments are 8 byte aligned */
1171 	if (mff && (ip_len & 0x7)) {
1172 		DPFPRINTF(("mff and %d\n", ip_len));
1173 		goto bad;
1174 	}
1175 
1176 	/* Respect maximum length */
1177 	if (fragoff + ip_len > IP_MAXPACKET) {
1178 		DPFPRINTF(("max packet %d\n", fragoff + ip_len));
1179 		goto bad;
1180 	}
1181 
1182 	if ((!scrub_compat && V_pf_status.reass) ||
1183 	    (r != NULL && !(r->rule_flag & PFRULE_FRAGMENT_NOREASS))
1184 	) {
1185 		max = fragoff + ip_len;
1186 
1187 		/* Fully buffer all of the fragments
1188 		 * Might return a completely reassembled mbuf, or NULL */
1189 		PF_FRAG_LOCK();
1190 		DPFPRINTF(("reass frag %d @ %d-%d\n", h->ip_id, fragoff, max));
1191 		verdict = pf_reassemble(&pd->m, pd->dir, reason);
1192 		PF_FRAG_UNLOCK();
1193 
1194 		if (verdict != PF_PASS)
1195 			return (PF_DROP);
1196 
1197 		if (pd->m == NULL)
1198 			return (PF_DROP);
1199 
1200 		h = mtod(pd->m, struct ip *);
1201 		pd->tot_len = htons(h->ip_len);
1202 
1203  no_fragment:
1204 		/* At this point, only IP_DF is allowed in ip_off */
1205 		if (h->ip_off & ~htons(IP_DF)) {
1206 			u_int16_t ip_off = h->ip_off;
1207 
1208 			h->ip_off &= htons(IP_DF);
1209 			h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
1210 		}
1211 	}
1212 
1213 	return (PF_PASS);
1214 
1215  bad:
1216 	DPFPRINTF(("dropping bad fragment\n"));
1217 	REASON_SET(reason, PFRES_FRAG);
1218  drop:
1219 	if (r != NULL && r->log)
1220 		PFLOG_PACKET(PF_DROP, *reason, r, NULL, NULL, pd, 1);
1221 
1222 	return (PF_DROP);
1223 }
1224 #endif
1225 
1226 #ifdef INET6
1227 int
pf_normalize_ip6(int off,u_short * reason,struct pf_pdesc * pd)1228 pf_normalize_ip6(int off, u_short *reason,
1229     struct pf_pdesc *pd)
1230 {
1231 	struct pf_krule		*r;
1232 	struct ip6_hdr		*h;
1233 	struct ip6_frag		 frag;
1234 	bool			 scrub_compat;
1235 
1236 	PF_RULES_RASSERT();
1237 
1238 	r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1239 	/*
1240 	 * Check if there are any scrub rules, matching or not.
1241 	 * Lack of scrub rules means:
1242 	 *  - enforced packet normalization operation just like in OpenBSD
1243 	 * With scrub rules:
1244 	 *  - packet normalization is performed if there is a matching scrub rule
1245 	 * XXX: Fragment reassembly always performed for IPv6!
1246 	 */
1247 	scrub_compat = (r != NULL);
1248 	while (r != NULL) {
1249 		pf_counter_u64_add(&r->evaluations, 1);
1250 		if (pfi_kkif_match(r->kif, pd->kif) == r->ifnot)
1251 			r = r->skip[PF_SKIP_IFP];
1252 		else if (r->direction && r->direction != pd->dir)
1253 			r = r->skip[PF_SKIP_DIR];
1254 		else if (r->af && r->af != AF_INET6)
1255 			r = r->skip[PF_SKIP_AF];
1256 		else if (r->proto && r->proto != pd->proto)
1257 			r = r->skip[PF_SKIP_PROTO];
1258 		else if (PF_MISMATCHAW(&r->src.addr,
1259 		    (struct pf_addr *)&pd->src, AF_INET6,
1260 		    r->src.neg, pd->kif, M_GETFIB(pd->m)))
1261 			r = r->skip[PF_SKIP_SRC_ADDR];
1262 		else if (PF_MISMATCHAW(&r->dst.addr,
1263 		    (struct pf_addr *)&pd->dst, AF_INET6,
1264 		    r->dst.neg, NULL, M_GETFIB(pd->m)))
1265 			r = r->skip[PF_SKIP_DST_ADDR];
1266 		else
1267 			break;
1268 	}
1269 
1270 	if (scrub_compat) {
1271 		/* With scrub rules present IPv6 normalization happens only
1272 		 * if one of rules has matched and it's not a "no scrub" rule */
1273 		if (r == NULL || r->action == PF_NOSCRUB)
1274 			return (PF_PASS);
1275 
1276 		pf_counter_u64_critical_enter();
1277 		pf_counter_u64_add_protected(&r->packets[pd->dir == PF_OUT], 1);
1278 		pf_counter_u64_add_protected(&r->bytes[pd->dir == PF_OUT], pd->tot_len);
1279 		pf_counter_u64_critical_exit();
1280 		pf_rule_to_actions(r, &pd->act);
1281 	}
1282 
1283 	if (!pf_pull_hdr(pd->m, off, &frag, sizeof(frag), NULL, reason, AF_INET6))
1284 		return (PF_DROP);
1285 
1286 	/* Offset now points to data portion. */
1287 	off += sizeof(frag);
1288 
1289 	if (pd->virtual_proto == PF_VPROTO_FRAGMENT) {
1290 		/* Returns PF_DROP or *m0 is NULL or completely reassembled
1291 		 * mbuf. */
1292 		if (pf_reassemble6(&pd->m, &frag, off, pd->extoff, reason) != PF_PASS)
1293 			return (PF_DROP);
1294 		if (pd->m == NULL)
1295 			return (PF_DROP);
1296 		h = mtod(pd->m, struct ip6_hdr *);
1297 		pd->tot_len = ntohs(h->ip6_plen) + sizeof(struct ip6_hdr);
1298 	}
1299 
1300 	return (PF_PASS);
1301 }
1302 #endif /* INET6 */
1303 
1304 int
pf_normalize_tcp(struct pf_pdesc * pd)1305 pf_normalize_tcp(struct pf_pdesc *pd)
1306 {
1307 	struct pf_krule	*r, *rm = NULL;
1308 	struct tcphdr	*th = &pd->hdr.tcp;
1309 	int		 rewrite = 0;
1310 	u_short		 reason;
1311 	u_int16_t	 flags;
1312 	sa_family_t	 af = pd->af;
1313 	int		 srs;
1314 
1315 	PF_RULES_RASSERT();
1316 
1317 	r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
1318 	/* Check if there any scrub rules. Lack of scrub rules means enforced
1319 	 * packet normalization operation just like in OpenBSD. */
1320 	srs = (r != NULL);
1321 	while (r != NULL) {
1322 		pf_counter_u64_add(&r->evaluations, 1);
1323 		if (pfi_kkif_match(r->kif, pd->kif) == r->ifnot)
1324 			r = r->skip[PF_SKIP_IFP];
1325 		else if (r->direction && r->direction != pd->dir)
1326 			r = r->skip[PF_SKIP_DIR];
1327 		else if (r->af && r->af != af)
1328 			r = r->skip[PF_SKIP_AF];
1329 		else if (r->proto && r->proto != pd->proto)
1330 			r = r->skip[PF_SKIP_PROTO];
1331 		else if (PF_MISMATCHAW(&r->src.addr, pd->src, af,
1332 		    r->src.neg, pd->kif, M_GETFIB(pd->m)))
1333 			r = r->skip[PF_SKIP_SRC_ADDR];
1334 		else if (r->src.port_op && !pf_match_port(r->src.port_op,
1335 			    r->src.port[0], r->src.port[1], th->th_sport))
1336 			r = r->skip[PF_SKIP_SRC_PORT];
1337 		else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af,
1338 		    r->dst.neg, NULL, M_GETFIB(pd->m)))
1339 			r = r->skip[PF_SKIP_DST_ADDR];
1340 		else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
1341 			    r->dst.port[0], r->dst.port[1], th->th_dport))
1342 			r = r->skip[PF_SKIP_DST_PORT];
1343 		else if (r->os_fingerprint != PF_OSFP_ANY && !pf_osfp_match(
1344 			    pf_osfp_fingerprint(pd, th),
1345 			    r->os_fingerprint))
1346 			r = TAILQ_NEXT(r, entries);
1347 		else {
1348 			rm = r;
1349 			break;
1350 		}
1351 	}
1352 
1353 	if (srs) {
1354 		/* With scrub rules present TCP normalization happens only
1355 		 * if one of rules has matched and it's not a "no scrub" rule */
1356 		if (rm == NULL || rm->action == PF_NOSCRUB)
1357 			return (PF_PASS);
1358 
1359 		pf_counter_u64_critical_enter();
1360 		pf_counter_u64_add_protected(&r->packets[pd->dir == PF_OUT], 1);
1361 		pf_counter_u64_add_protected(&r->bytes[pd->dir == PF_OUT], pd->tot_len);
1362 		pf_counter_u64_critical_exit();
1363 		pf_rule_to_actions(rm, &pd->act);
1364 	}
1365 
1366 	if (rm && rm->rule_flag & PFRULE_REASSEMBLE_TCP)
1367 		pd->flags |= PFDESC_TCP_NORM;
1368 
1369 	flags = tcp_get_flags(th);
1370 	if (flags & TH_SYN) {
1371 		/* Illegal packet */
1372 		if (flags & TH_RST)
1373 			goto tcp_drop;
1374 
1375 		if (flags & TH_FIN)
1376 			goto tcp_drop;
1377 	} else {
1378 		/* Illegal packet */
1379 		if (!(flags & (TH_ACK|TH_RST)))
1380 			goto tcp_drop;
1381 	}
1382 
1383 	if (!(flags & TH_ACK)) {
1384 		/* These flags are only valid if ACK is set */
1385 		if ((flags & TH_FIN) || (flags & TH_PUSH) || (flags & TH_URG))
1386 			goto tcp_drop;
1387 	}
1388 
1389 	/* Check for illegal header length */
1390 	if (th->th_off < (sizeof(struct tcphdr) >> 2))
1391 		goto tcp_drop;
1392 
1393 	/* If flags changed, or reserved data set, then adjust */
1394 	if (flags != tcp_get_flags(th) ||
1395 	    (tcp_get_flags(th) & (TH_RES1|TH_RES2|TH_RES2)) != 0) {
1396 		u_int16_t	ov, nv;
1397 
1398 		ov = *(u_int16_t *)(&th->th_ack + 1);
1399 		flags &= ~(TH_RES1 | TH_RES2 | TH_RES3);
1400 		tcp_set_flags(th, flags);
1401 		nv = *(u_int16_t *)(&th->th_ack + 1);
1402 
1403 		th->th_sum = pf_proto_cksum_fixup(pd->m, th->th_sum, ov, nv, 0);
1404 		rewrite = 1;
1405 	}
1406 
1407 	/* Remove urgent pointer, if TH_URG is not set */
1408 	if (!(flags & TH_URG) && th->th_urp) {
1409 		th->th_sum = pf_proto_cksum_fixup(pd->m, th->th_sum, th->th_urp,
1410 		    0, 0);
1411 		th->th_urp = 0;
1412 		rewrite = 1;
1413 	}
1414 
1415 	/* copy back packet headers if we sanitized */
1416 	if (rewrite)
1417 		m_copyback(pd->m, pd->off, sizeof(*th), (caddr_t)th);
1418 
1419 	return (PF_PASS);
1420 
1421  tcp_drop:
1422 	REASON_SET(&reason, PFRES_NORM);
1423 	if (rm != NULL && r->log)
1424 		PFLOG_PACKET(PF_DROP, reason, r, NULL, NULL, pd, 1);
1425 	return (PF_DROP);
1426 }
1427 
1428 int
pf_normalize_tcp_init(struct pf_pdesc * pd,struct tcphdr * th,struct pf_state_peer * src,struct pf_state_peer * dst)1429 pf_normalize_tcp_init(struct pf_pdesc *pd, struct tcphdr *th,
1430     struct pf_state_peer *src, struct pf_state_peer *dst)
1431 {
1432 	u_int32_t tsval, tsecr;
1433 	u_int8_t hdr[60];
1434 	u_int8_t *opt;
1435 
1436 	KASSERT((src->scrub == NULL),
1437 	    ("pf_normalize_tcp_init: src->scrub != NULL"));
1438 
1439 	src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT);
1440 	if (src->scrub == NULL)
1441 		return (1);
1442 
1443 	switch (pd->af) {
1444 #ifdef INET
1445 	case AF_INET: {
1446 		struct ip *h = mtod(pd->m, struct ip *);
1447 		src->scrub->pfss_ttl = h->ip_ttl;
1448 		break;
1449 	}
1450 #endif /* INET */
1451 #ifdef INET6
1452 	case AF_INET6: {
1453 		struct ip6_hdr *h = mtod(pd->m, struct ip6_hdr *);
1454 		src->scrub->pfss_ttl = h->ip6_hlim;
1455 		break;
1456 	}
1457 #endif /* INET6 */
1458 	}
1459 
1460 	/*
1461 	 * All normalizations below are only begun if we see the start of
1462 	 * the connections.  They must all set an enabled bit in pfss_flags
1463 	 */
1464 	if ((tcp_get_flags(th) & TH_SYN) == 0)
1465 		return (0);
1466 
1467 	if (th->th_off > (sizeof(struct tcphdr) >> 2) && src->scrub &&
1468 	    pf_pull_hdr(pd->m, pd->off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1469 		/* Diddle with TCP options */
1470 		int hlen;
1471 		opt = hdr + sizeof(struct tcphdr);
1472 		hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1473 		while (hlen >= TCPOLEN_TIMESTAMP) {
1474 			switch (*opt) {
1475 			case TCPOPT_EOL:	/* FALLTHROUGH */
1476 			case TCPOPT_NOP:
1477 				opt++;
1478 				hlen--;
1479 				break;
1480 			case TCPOPT_TIMESTAMP:
1481 				if (opt[1] >= TCPOLEN_TIMESTAMP) {
1482 					src->scrub->pfss_flags |=
1483 					    PFSS_TIMESTAMP;
1484 					src->scrub->pfss_ts_mod =
1485 					    htonl(arc4random());
1486 
1487 					/* note PFSS_PAWS not set yet */
1488 					memcpy(&tsval, &opt[2],
1489 					    sizeof(u_int32_t));
1490 					memcpy(&tsecr, &opt[6],
1491 					    sizeof(u_int32_t));
1492 					src->scrub->pfss_tsval0 = ntohl(tsval);
1493 					src->scrub->pfss_tsval = ntohl(tsval);
1494 					src->scrub->pfss_tsecr = ntohl(tsecr);
1495 					getmicrouptime(&src->scrub->pfss_last);
1496 				}
1497 				/* FALLTHROUGH */
1498 			default:
1499 				hlen -= MAX(opt[1], 2);
1500 				opt += MAX(opt[1], 2);
1501 				break;
1502 			}
1503 		}
1504 	}
1505 
1506 	return (0);
1507 }
1508 
1509 void
pf_normalize_tcp_cleanup(struct pf_kstate * state)1510 pf_normalize_tcp_cleanup(struct pf_kstate *state)
1511 {
1512 	/* XXX Note: this also cleans up SCTP. */
1513 	uma_zfree(V_pf_state_scrub_z, state->src.scrub);
1514 	uma_zfree(V_pf_state_scrub_z, state->dst.scrub);
1515 
1516 	/* Someday... flush the TCP segment reassembly descriptors. */
1517 }
1518 int
pf_normalize_sctp_init(struct pf_pdesc * pd,struct pf_state_peer * src,struct pf_state_peer * dst)1519 pf_normalize_sctp_init(struct pf_pdesc *pd, struct pf_state_peer *src,
1520     struct pf_state_peer *dst)
1521 {
1522 	src->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT);
1523 	if (src->scrub == NULL)
1524 		return (1);
1525 
1526 	dst->scrub = uma_zalloc(V_pf_state_scrub_z, M_ZERO | M_NOWAIT);
1527 	if (dst->scrub == NULL) {
1528 		uma_zfree(V_pf_state_scrub_z, src);
1529 		return (1);
1530 	}
1531 
1532 	dst->scrub->pfss_v_tag = pd->sctp_initiate_tag;
1533 
1534 	return (0);
1535 }
1536 
1537 int
pf_normalize_tcp_stateful(struct pf_pdesc * pd,u_short * reason,struct tcphdr * th,struct pf_kstate * state,struct pf_state_peer * src,struct pf_state_peer * dst,int * writeback)1538 pf_normalize_tcp_stateful(struct pf_pdesc *pd,
1539     u_short *reason, struct tcphdr *th, struct pf_kstate *state,
1540     struct pf_state_peer *src, struct pf_state_peer *dst, int *writeback)
1541 {
1542 	struct timeval uptime;
1543 	u_int32_t tsval, tsecr;
1544 	u_int tsval_from_last;
1545 	u_int8_t hdr[60];
1546 	u_int8_t *opt;
1547 	int copyback = 0;
1548 	int got_ts = 0;
1549 	size_t startoff;
1550 
1551 	KASSERT((src->scrub || dst->scrub),
1552 	    ("%s: src->scrub && dst->scrub!", __func__));
1553 
1554 	/*
1555 	 * Enforce the minimum TTL seen for this connection.  Negate a common
1556 	 * technique to evade an intrusion detection system and confuse
1557 	 * firewall state code.
1558 	 */
1559 	switch (pd->af) {
1560 #ifdef INET
1561 	case AF_INET: {
1562 		if (src->scrub) {
1563 			struct ip *h = mtod(pd->m, struct ip *);
1564 			if (h->ip_ttl > src->scrub->pfss_ttl)
1565 				src->scrub->pfss_ttl = h->ip_ttl;
1566 			h->ip_ttl = src->scrub->pfss_ttl;
1567 		}
1568 		break;
1569 	}
1570 #endif /* INET */
1571 #ifdef INET6
1572 	case AF_INET6: {
1573 		if (src->scrub) {
1574 			struct ip6_hdr *h = mtod(pd->m, struct ip6_hdr *);
1575 			if (h->ip6_hlim > src->scrub->pfss_ttl)
1576 				src->scrub->pfss_ttl = h->ip6_hlim;
1577 			h->ip6_hlim = src->scrub->pfss_ttl;
1578 		}
1579 		break;
1580 	}
1581 #endif /* INET6 */
1582 	}
1583 
1584 	if (th->th_off > (sizeof(struct tcphdr) >> 2) &&
1585 	    ((src->scrub && (src->scrub->pfss_flags & PFSS_TIMESTAMP)) ||
1586 	    (dst->scrub && (dst->scrub->pfss_flags & PFSS_TIMESTAMP))) &&
1587 	    pf_pull_hdr(pd->m, pd->off, hdr, th->th_off << 2, NULL, NULL, pd->af)) {
1588 		/* Diddle with TCP options */
1589 		int hlen;
1590 		opt = hdr + sizeof(struct tcphdr);
1591 		hlen = (th->th_off << 2) - sizeof(struct tcphdr);
1592 		while (hlen >= TCPOLEN_TIMESTAMP) {
1593 			startoff = opt - (hdr + sizeof(struct tcphdr));
1594 			switch (*opt) {
1595 			case TCPOPT_EOL:	/* FALLTHROUGH */
1596 			case TCPOPT_NOP:
1597 				opt++;
1598 				hlen--;
1599 				break;
1600 			case TCPOPT_TIMESTAMP:
1601 				/* Modulate the timestamps.  Can be used for
1602 				 * NAT detection, OS uptime determination or
1603 				 * reboot detection.
1604 				 */
1605 
1606 				if (got_ts) {
1607 					/* Huh?  Multiple timestamps!? */
1608 					if (V_pf_status.debug >= PF_DEBUG_MISC) {
1609 						DPFPRINTF(("multiple TS??\n"));
1610 						pf_print_state(state);
1611 						printf("\n");
1612 					}
1613 					REASON_SET(reason, PFRES_TS);
1614 					return (PF_DROP);
1615 				}
1616 				if (opt[1] >= TCPOLEN_TIMESTAMP) {
1617 					memcpy(&tsval, &opt[2],
1618 					    sizeof(u_int32_t));
1619 					if (tsval && src->scrub &&
1620 					    (src->scrub->pfss_flags &
1621 					    PFSS_TIMESTAMP)) {
1622 						tsval = ntohl(tsval);
1623 						pf_patch_32_unaligned(pd->m,
1624 						    &th->th_sum,
1625 						    &opt[2],
1626 						    htonl(tsval +
1627 						    src->scrub->pfss_ts_mod),
1628 						    PF_ALGNMNT(startoff),
1629 						    0);
1630 						copyback = 1;
1631 					}
1632 
1633 					/* Modulate TS reply iff valid (!0) */
1634 					memcpy(&tsecr, &opt[6],
1635 					    sizeof(u_int32_t));
1636 					if (tsecr && dst->scrub &&
1637 					    (dst->scrub->pfss_flags &
1638 					    PFSS_TIMESTAMP)) {
1639 						tsecr = ntohl(tsecr)
1640 						    - dst->scrub->pfss_ts_mod;
1641 						pf_patch_32_unaligned(pd->m,
1642 						    &th->th_sum,
1643 						    &opt[6],
1644 						    htonl(tsecr),
1645 						    PF_ALGNMNT(startoff),
1646 						    0);
1647 						copyback = 1;
1648 					}
1649 					got_ts = 1;
1650 				}
1651 				/* FALLTHROUGH */
1652 			default:
1653 				hlen -= MAX(opt[1], 2);
1654 				opt += MAX(opt[1], 2);
1655 				break;
1656 			}
1657 		}
1658 		if (copyback) {
1659 			/* Copyback the options, caller copys back header */
1660 			*writeback = 1;
1661 			m_copyback(pd->m, pd->off + sizeof(struct tcphdr),
1662 			    (th->th_off << 2) - sizeof(struct tcphdr), hdr +
1663 			    sizeof(struct tcphdr));
1664 		}
1665 	}
1666 
1667 	/*
1668 	 * Must invalidate PAWS checks on connections idle for too long.
1669 	 * The fastest allowed timestamp clock is 1ms.  That turns out to
1670 	 * be about 24 days before it wraps.  XXX Right now our lowerbound
1671 	 * TS echo check only works for the first 12 days of a connection
1672 	 * when the TS has exhausted half its 32bit space
1673 	 */
1674 #define TS_MAX_IDLE	(24*24*60*60)
1675 #define TS_MAX_CONN	(12*24*60*60)	/* XXX remove when better tsecr check */
1676 
1677 	getmicrouptime(&uptime);
1678 	if (src->scrub && (src->scrub->pfss_flags & PFSS_PAWS) &&
1679 	    (uptime.tv_sec - src->scrub->pfss_last.tv_sec > TS_MAX_IDLE ||
1680 	    time_uptime - (state->creation / 1000) > TS_MAX_CONN))  {
1681 		if (V_pf_status.debug >= PF_DEBUG_MISC) {
1682 			DPFPRINTF(("src idled out of PAWS\n"));
1683 			pf_print_state(state);
1684 			printf("\n");
1685 		}
1686 		src->scrub->pfss_flags = (src->scrub->pfss_flags & ~PFSS_PAWS)
1687 		    | PFSS_PAWS_IDLED;
1688 	}
1689 	if (dst->scrub && (dst->scrub->pfss_flags & PFSS_PAWS) &&
1690 	    uptime.tv_sec - dst->scrub->pfss_last.tv_sec > TS_MAX_IDLE) {
1691 		if (V_pf_status.debug >= PF_DEBUG_MISC) {
1692 			DPFPRINTF(("dst idled out of PAWS\n"));
1693 			pf_print_state(state);
1694 			printf("\n");
1695 		}
1696 		dst->scrub->pfss_flags = (dst->scrub->pfss_flags & ~PFSS_PAWS)
1697 		    | PFSS_PAWS_IDLED;
1698 	}
1699 
1700 	if (got_ts && src->scrub && dst->scrub &&
1701 	    (src->scrub->pfss_flags & PFSS_PAWS) &&
1702 	    (dst->scrub->pfss_flags & PFSS_PAWS)) {
1703 		/* Validate that the timestamps are "in-window".
1704 		 * RFC1323 describes TCP Timestamp options that allow
1705 		 * measurement of RTT (round trip time) and PAWS
1706 		 * (protection against wrapped sequence numbers).  PAWS
1707 		 * gives us a set of rules for rejecting packets on
1708 		 * long fat pipes (packets that were somehow delayed
1709 		 * in transit longer than the time it took to send the
1710 		 * full TCP sequence space of 4Gb).  We can use these
1711 		 * rules and infer a few others that will let us treat
1712 		 * the 32bit timestamp and the 32bit echoed timestamp
1713 		 * as sequence numbers to prevent a blind attacker from
1714 		 * inserting packets into a connection.
1715 		 *
1716 		 * RFC1323 tells us:
1717 		 *  - The timestamp on this packet must be greater than
1718 		 *    or equal to the last value echoed by the other
1719 		 *    endpoint.  The RFC says those will be discarded
1720 		 *    since it is a dup that has already been acked.
1721 		 *    This gives us a lowerbound on the timestamp.
1722 		 *        timestamp >= other last echoed timestamp
1723 		 *  - The timestamp will be less than or equal to
1724 		 *    the last timestamp plus the time between the
1725 		 *    last packet and now.  The RFC defines the max
1726 		 *    clock rate as 1ms.  We will allow clocks to be
1727 		 *    up to 10% fast and will allow a total difference
1728 		 *    or 30 seconds due to a route change.  And this
1729 		 *    gives us an upperbound on the timestamp.
1730 		 *        timestamp <= last timestamp + max ticks
1731 		 *    We have to be careful here.  Windows will send an
1732 		 *    initial timestamp of zero and then initialize it
1733 		 *    to a random value after the 3whs; presumably to
1734 		 *    avoid a DoS by having to call an expensive RNG
1735 		 *    during a SYN flood.  Proof MS has at least one
1736 		 *    good security geek.
1737 		 *
1738 		 *  - The TCP timestamp option must also echo the other
1739 		 *    endpoints timestamp.  The timestamp echoed is the
1740 		 *    one carried on the earliest unacknowledged segment
1741 		 *    on the left edge of the sequence window.  The RFC
1742 		 *    states that the host will reject any echoed
1743 		 *    timestamps that were larger than any ever sent.
1744 		 *    This gives us an upperbound on the TS echo.
1745 		 *        tescr <= largest_tsval
1746 		 *  - The lowerbound on the TS echo is a little more
1747 		 *    tricky to determine.  The other endpoint's echoed
1748 		 *    values will not decrease.  But there may be
1749 		 *    network conditions that re-order packets and
1750 		 *    cause our view of them to decrease.  For now the
1751 		 *    only lowerbound we can safely determine is that
1752 		 *    the TS echo will never be less than the original
1753 		 *    TS.  XXX There is probably a better lowerbound.
1754 		 *    Remove TS_MAX_CONN with better lowerbound check.
1755 		 *        tescr >= other original TS
1756 		 *
1757 		 * It is also important to note that the fastest
1758 		 * timestamp clock of 1ms will wrap its 32bit space in
1759 		 * 24 days.  So we just disable TS checking after 24
1760 		 * days of idle time.  We actually must use a 12d
1761 		 * connection limit until we can come up with a better
1762 		 * lowerbound to the TS echo check.
1763 		 */
1764 		struct timeval delta_ts;
1765 		int ts_fudge;
1766 
1767 		/*
1768 		 * PFTM_TS_DIFF is how many seconds of leeway to allow
1769 		 * a host's timestamp.  This can happen if the previous
1770 		 * packet got delayed in transit for much longer than
1771 		 * this packet.
1772 		 */
1773 		if ((ts_fudge = state->rule->timeout[PFTM_TS_DIFF]) == 0)
1774 			ts_fudge = V_pf_default_rule.timeout[PFTM_TS_DIFF];
1775 
1776 		/* Calculate max ticks since the last timestamp */
1777 #define TS_MAXFREQ	1100		/* RFC max TS freq of 1Khz + 10% skew */
1778 #define TS_MICROSECS	1000000		/* microseconds per second */
1779 		delta_ts = uptime;
1780 		timevalsub(&delta_ts, &src->scrub->pfss_last);
1781 		tsval_from_last = (delta_ts.tv_sec + ts_fudge) * TS_MAXFREQ;
1782 		tsval_from_last += delta_ts.tv_usec / (TS_MICROSECS/TS_MAXFREQ);
1783 
1784 		if ((src->state >= TCPS_ESTABLISHED &&
1785 		    dst->state >= TCPS_ESTABLISHED) &&
1786 		    (SEQ_LT(tsval, dst->scrub->pfss_tsecr) ||
1787 		    SEQ_GT(tsval, src->scrub->pfss_tsval + tsval_from_last) ||
1788 		    (tsecr && (SEQ_GT(tsecr, dst->scrub->pfss_tsval) ||
1789 		    SEQ_LT(tsecr, dst->scrub->pfss_tsval0))))) {
1790 			/* Bad RFC1323 implementation or an insertion attack.
1791 			 *
1792 			 * - Solaris 2.6 and 2.7 are known to send another ACK
1793 			 *   after the FIN,FIN|ACK,ACK closing that carries
1794 			 *   an old timestamp.
1795 			 */
1796 
1797 			DPFPRINTF(("Timestamp failed %c%c%c%c\n",
1798 			    SEQ_LT(tsval, dst->scrub->pfss_tsecr) ? '0' : ' ',
1799 			    SEQ_GT(tsval, src->scrub->pfss_tsval +
1800 			    tsval_from_last) ? '1' : ' ',
1801 			    SEQ_GT(tsecr, dst->scrub->pfss_tsval) ? '2' : ' ',
1802 			    SEQ_LT(tsecr, dst->scrub->pfss_tsval0)? '3' : ' '));
1803 			DPFPRINTF((" tsval: %u  tsecr: %u  +ticks: %u  "
1804 			    "idle: %jus %lums\n",
1805 			    tsval, tsecr, tsval_from_last,
1806 			    (uintmax_t)delta_ts.tv_sec,
1807 			    delta_ts.tv_usec / 1000));
1808 			DPFPRINTF((" src->tsval: %u  tsecr: %u\n",
1809 			    src->scrub->pfss_tsval, src->scrub->pfss_tsecr));
1810 			DPFPRINTF((" dst->tsval: %u  tsecr: %u  tsval0: %u"
1811 			    "\n", dst->scrub->pfss_tsval,
1812 			    dst->scrub->pfss_tsecr, dst->scrub->pfss_tsval0));
1813 			if (V_pf_status.debug >= PF_DEBUG_MISC) {
1814 				pf_print_state(state);
1815 				pf_print_flags(tcp_get_flags(th));
1816 				printf("\n");
1817 			}
1818 			REASON_SET(reason, PFRES_TS);
1819 			return (PF_DROP);
1820 		}
1821 
1822 		/* XXX I'd really like to require tsecr but it's optional */
1823 
1824 	} else if (!got_ts && (tcp_get_flags(th) & TH_RST) == 0 &&
1825 	    ((src->state == TCPS_ESTABLISHED && dst->state == TCPS_ESTABLISHED)
1826 	    || pd->p_len > 0 || (tcp_get_flags(th) & TH_SYN)) &&
1827 	    src->scrub && dst->scrub &&
1828 	    (src->scrub->pfss_flags & PFSS_PAWS) &&
1829 	    (dst->scrub->pfss_flags & PFSS_PAWS)) {
1830 		/* Didn't send a timestamp.  Timestamps aren't really useful
1831 		 * when:
1832 		 *  - connection opening or closing (often not even sent).
1833 		 *    but we must not let an attacker to put a FIN on a
1834 		 *    data packet to sneak it through our ESTABLISHED check.
1835 		 *  - on a TCP reset.  RFC suggests not even looking at TS.
1836 		 *  - on an empty ACK.  The TS will not be echoed so it will
1837 		 *    probably not help keep the RTT calculation in sync and
1838 		 *    there isn't as much danger when the sequence numbers
1839 		 *    got wrapped.  So some stacks don't include TS on empty
1840 		 *    ACKs :-(
1841 		 *
1842 		 * To minimize the disruption to mostly RFC1323 conformant
1843 		 * stacks, we will only require timestamps on data packets.
1844 		 *
1845 		 * And what do ya know, we cannot require timestamps on data
1846 		 * packets.  There appear to be devices that do legitimate
1847 		 * TCP connection hijacking.  There are HTTP devices that allow
1848 		 * a 3whs (with timestamps) and then buffer the HTTP request.
1849 		 * If the intermediate device has the HTTP response cache, it
1850 		 * will spoof the response but not bother timestamping its
1851 		 * packets.  So we can look for the presence of a timestamp in
1852 		 * the first data packet and if there, require it in all future
1853 		 * packets.
1854 		 */
1855 
1856 		if (pd->p_len > 0 && (src->scrub->pfss_flags & PFSS_DATA_TS)) {
1857 			/*
1858 			 * Hey!  Someone tried to sneak a packet in.  Or the
1859 			 * stack changed its RFC1323 behavior?!?!
1860 			 */
1861 			if (V_pf_status.debug >= PF_DEBUG_MISC) {
1862 				DPFPRINTF(("Did not receive expected RFC1323 "
1863 				    "timestamp\n"));
1864 				pf_print_state(state);
1865 				pf_print_flags(tcp_get_flags(th));
1866 				printf("\n");
1867 			}
1868 			REASON_SET(reason, PFRES_TS);
1869 			return (PF_DROP);
1870 		}
1871 	}
1872 
1873 	/*
1874 	 * We will note if a host sends his data packets with or without
1875 	 * timestamps.  And require all data packets to contain a timestamp
1876 	 * if the first does.  PAWS implicitly requires that all data packets be
1877 	 * timestamped.  But I think there are middle-man devices that hijack
1878 	 * TCP streams immediately after the 3whs and don't timestamp their
1879 	 * packets (seen in a WWW accelerator or cache).
1880 	 */
1881 	if (pd->p_len > 0 && src->scrub && (src->scrub->pfss_flags &
1882 	    (PFSS_TIMESTAMP|PFSS_DATA_TS|PFSS_DATA_NOTS)) == PFSS_TIMESTAMP) {
1883 		if (got_ts)
1884 			src->scrub->pfss_flags |= PFSS_DATA_TS;
1885 		else {
1886 			src->scrub->pfss_flags |= PFSS_DATA_NOTS;
1887 			if (V_pf_status.debug >= PF_DEBUG_MISC && dst->scrub &&
1888 			    (dst->scrub->pfss_flags & PFSS_TIMESTAMP)) {
1889 				/* Don't warn if other host rejected RFC1323 */
1890 				DPFPRINTF(("Broken RFC1323 stack did not "
1891 				    "timestamp data packet. Disabled PAWS "
1892 				    "security.\n"));
1893 				pf_print_state(state);
1894 				pf_print_flags(tcp_get_flags(th));
1895 				printf("\n");
1896 			}
1897 		}
1898 	}
1899 
1900 	/*
1901 	 * Update PAWS values
1902 	 */
1903 	if (got_ts && src->scrub && PFSS_TIMESTAMP == (src->scrub->pfss_flags &
1904 	    (PFSS_PAWS_IDLED|PFSS_TIMESTAMP))) {
1905 		getmicrouptime(&src->scrub->pfss_last);
1906 		if (SEQ_GEQ(tsval, src->scrub->pfss_tsval) ||
1907 		    (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1908 			src->scrub->pfss_tsval = tsval;
1909 
1910 		if (tsecr) {
1911 			if (SEQ_GEQ(tsecr, src->scrub->pfss_tsecr) ||
1912 			    (src->scrub->pfss_flags & PFSS_PAWS) == 0)
1913 				src->scrub->pfss_tsecr = tsecr;
1914 
1915 			if ((src->scrub->pfss_flags & PFSS_PAWS) == 0 &&
1916 			    (SEQ_LT(tsval, src->scrub->pfss_tsval0) ||
1917 			    src->scrub->pfss_tsval0 == 0)) {
1918 				/* tsval0 MUST be the lowest timestamp */
1919 				src->scrub->pfss_tsval0 = tsval;
1920 			}
1921 
1922 			/* Only fully initialized after a TS gets echoed */
1923 			if ((src->scrub->pfss_flags & PFSS_PAWS) == 0)
1924 				src->scrub->pfss_flags |= PFSS_PAWS;
1925 		}
1926 	}
1927 
1928 	/* I have a dream....  TCP segment reassembly.... */
1929 	return (0);
1930 }
1931 
1932 int
pf_normalize_mss(struct pf_pdesc * pd)1933 pf_normalize_mss(struct pf_pdesc *pd)
1934 {
1935 	struct tcphdr	*th = &pd->hdr.tcp;
1936 	u_int16_t	*mss;
1937 	int		 thoff;
1938 	int		 opt, cnt, optlen = 0;
1939 	u_char		 opts[TCP_MAXOLEN];
1940 	u_char		*optp = opts;
1941 	size_t		 startoff;
1942 
1943 	thoff = th->th_off << 2;
1944 	cnt = thoff - sizeof(struct tcphdr);
1945 
1946 	if (cnt <= 0 || cnt > MAX_TCPOPTLEN || !pf_pull_hdr(pd->m,
1947 	    pd->off + sizeof(*th), opts, cnt, NULL, NULL, pd->af))
1948 		return (0);
1949 
1950 	for (; cnt > 0; cnt -= optlen, optp += optlen) {
1951 		startoff = optp - opts;
1952 		opt = optp[0];
1953 		if (opt == TCPOPT_EOL)
1954 			break;
1955 		if (opt == TCPOPT_NOP)
1956 			optlen = 1;
1957 		else {
1958 			if (cnt < 2)
1959 				break;
1960 			optlen = optp[1];
1961 			if (optlen < 2 || optlen > cnt)
1962 				break;
1963 		}
1964 		switch (opt) {
1965 		case TCPOPT_MAXSEG:
1966 			mss = (u_int16_t *)(optp + 2);
1967 			if ((ntohs(*mss)) > pd->act.max_mss) {
1968 				pf_patch_16_unaligned(pd->m,
1969 				    &th->th_sum,
1970 				    mss, htons(pd->act.max_mss),
1971 				    PF_ALGNMNT(startoff),
1972 				    0);
1973 				m_copyback(pd->m, pd->off + sizeof(*th),
1974 				    thoff - sizeof(*th), opts);
1975 				m_copyback(pd->m, pd->off, sizeof(*th), (caddr_t)th);
1976 			}
1977 			break;
1978 		default:
1979 			break;
1980 		}
1981 	}
1982 
1983 	return (0);
1984 }
1985 
1986 int
pf_scan_sctp(struct pf_pdesc * pd)1987 pf_scan_sctp(struct pf_pdesc *pd)
1988 {
1989 	struct sctp_chunkhdr ch = { };
1990 	int chunk_off = sizeof(struct sctphdr);
1991 	int chunk_start;
1992 	int ret;
1993 
1994 	while (pd->off + chunk_off < pd->tot_len) {
1995 		if (!pf_pull_hdr(pd->m, pd->off + chunk_off, &ch, sizeof(ch), NULL,
1996 		    NULL, pd->af))
1997 			return (PF_DROP);
1998 
1999 		/* Length includes the header, this must be at least 4. */
2000 		if (ntohs(ch.chunk_length) < 4)
2001 			return (PF_DROP);
2002 
2003 		chunk_start = chunk_off;
2004 		chunk_off += roundup(ntohs(ch.chunk_length), 4);
2005 
2006 		switch (ch.chunk_type) {
2007 		case SCTP_INITIATION:
2008 		case SCTP_INITIATION_ACK: {
2009 			struct sctp_init_chunk init;
2010 
2011 			if (!pf_pull_hdr(pd->m, pd->off + chunk_start, &init,
2012 			    sizeof(init), NULL, NULL, pd->af))
2013 				return (PF_DROP);
2014 
2015 			/*
2016 			 * RFC 9620, Section 3.3.2, "The Initiate Tag is allowed to have
2017 			 * any value except 0."
2018 			 */
2019 			if (init.init.initiate_tag == 0)
2020 				return (PF_DROP);
2021 			if (init.init.num_inbound_streams == 0)
2022 				return (PF_DROP);
2023 			if (init.init.num_outbound_streams == 0)
2024 				return (PF_DROP);
2025 			if (ntohl(init.init.a_rwnd) < SCTP_MIN_RWND)
2026 				return (PF_DROP);
2027 
2028 			/*
2029 			 * RFC 9260, Section 3.1, INIT chunks MUST have zero
2030 			 * verification tag.
2031 			 */
2032 			if (ch.chunk_type == SCTP_INITIATION &&
2033 			    pd->hdr.sctp.v_tag != 0)
2034 				return (PF_DROP);
2035 
2036 			pd->sctp_initiate_tag = init.init.initiate_tag;
2037 
2038 			if (ch.chunk_type == SCTP_INITIATION)
2039 				pd->sctp_flags |= PFDESC_SCTP_INIT;
2040 			else
2041 				pd->sctp_flags |= PFDESC_SCTP_INIT_ACK;
2042 
2043 			ret = pf_multihome_scan_init(pd->off + chunk_start,
2044 			    ntohs(init.ch.chunk_length), pd);
2045 			if (ret != PF_PASS)
2046 				return (ret);
2047 
2048 			break;
2049 		}
2050 		case SCTP_ABORT_ASSOCIATION:
2051 			pd->sctp_flags |= PFDESC_SCTP_ABORT;
2052 			break;
2053 		case SCTP_SHUTDOWN:
2054 		case SCTP_SHUTDOWN_ACK:
2055 			pd->sctp_flags |= PFDESC_SCTP_SHUTDOWN;
2056 			break;
2057 		case SCTP_SHUTDOWN_COMPLETE:
2058 			pd->sctp_flags |= PFDESC_SCTP_SHUTDOWN_COMPLETE;
2059 			break;
2060 		case SCTP_COOKIE_ECHO:
2061 			pd->sctp_flags |= PFDESC_SCTP_COOKIE;
2062 			break;
2063 		case SCTP_COOKIE_ACK:
2064 			pd->sctp_flags |= PFDESC_SCTP_COOKIE_ACK;
2065 			break;
2066 		case SCTP_DATA:
2067 			pd->sctp_flags |= PFDESC_SCTP_DATA;
2068 			break;
2069 		case SCTP_HEARTBEAT_REQUEST:
2070 			pd->sctp_flags |= PFDESC_SCTP_HEARTBEAT;
2071 			break;
2072 		case SCTP_HEARTBEAT_ACK:
2073 			pd->sctp_flags |= PFDESC_SCTP_HEARTBEAT_ACK;
2074 			break;
2075 		case SCTP_ASCONF:
2076 			pd->sctp_flags |= PFDESC_SCTP_ASCONF;
2077 
2078 			ret = pf_multihome_scan_asconf(pd->off + chunk_start,
2079 			    ntohs(ch.chunk_length), pd);
2080 			if (ret != PF_PASS)
2081 				return (ret);
2082 			break;
2083 		default:
2084 			pd->sctp_flags |= PFDESC_SCTP_OTHER;
2085 			break;
2086 		}
2087 	}
2088 
2089 	/* Validate chunk lengths vs. packet length. */
2090 	if (pd->off + chunk_off != pd->tot_len)
2091 		return (PF_DROP);
2092 
2093 	/*
2094 	 * INIT, INIT_ACK or SHUTDOWN_COMPLETE chunks must always be the only
2095 	 * one in a packet.
2096 	 */
2097 	if ((pd->sctp_flags & PFDESC_SCTP_INIT) &&
2098 	    (pd->sctp_flags & ~PFDESC_SCTP_INIT))
2099 		return (PF_DROP);
2100 	if ((pd->sctp_flags & PFDESC_SCTP_INIT_ACK) &&
2101 	    (pd->sctp_flags & ~PFDESC_SCTP_INIT_ACK))
2102 		return (PF_DROP);
2103 	if ((pd->sctp_flags & PFDESC_SCTP_SHUTDOWN_COMPLETE) &&
2104 	    (pd->sctp_flags & ~PFDESC_SCTP_SHUTDOWN_COMPLETE))
2105 		return (PF_DROP);
2106 	if ((pd->sctp_flags & PFDESC_SCTP_ABORT) &&
2107 	    (pd->sctp_flags & PFDESC_SCTP_DATA)) {
2108 		/*
2109 		 * RFC4960 3.3.7: DATA chunks MUST NOT be
2110 		 * bundled with ABORT.
2111 		 */
2112 		return (PF_DROP);
2113 	}
2114 
2115 	return (PF_PASS);
2116 }
2117 
2118 int
pf_normalize_sctp(struct pf_pdesc * pd)2119 pf_normalize_sctp(struct pf_pdesc *pd)
2120 {
2121 	struct pf_krule	*r, *rm = NULL;
2122 	struct sctphdr	*sh = &pd->hdr.sctp;
2123 	u_short		 reason;
2124 	sa_family_t	 af = pd->af;
2125 	int		 srs;
2126 
2127 	PF_RULES_RASSERT();
2128 
2129 	r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
2130 	/* Check if there any scrub rules. Lack of scrub rules means enforced
2131 	 * packet normalization operation just like in OpenBSD. */
2132 	srs = (r != NULL);
2133 	while (r != NULL) {
2134 		pf_counter_u64_add(&r->evaluations, 1);
2135 		if (pfi_kkif_match(r->kif, pd->kif) == r->ifnot)
2136 			r = r->skip[PF_SKIP_IFP];
2137 		else if (r->direction && r->direction != pd->dir)
2138 			r = r->skip[PF_SKIP_DIR];
2139 		else if (r->af && r->af != af)
2140 			r = r->skip[PF_SKIP_AF];
2141 		else if (r->proto && r->proto != pd->proto)
2142 			r = r->skip[PF_SKIP_PROTO];
2143 		else if (PF_MISMATCHAW(&r->src.addr, pd->src, af,
2144 		    r->src.neg, pd->kif, M_GETFIB(pd->m)))
2145 			r = r->skip[PF_SKIP_SRC_ADDR];
2146 		else if (r->src.port_op && !pf_match_port(r->src.port_op,
2147 			    r->src.port[0], r->src.port[1], sh->src_port))
2148 			r = r->skip[PF_SKIP_SRC_PORT];
2149 		else if (PF_MISMATCHAW(&r->dst.addr, pd->dst, af,
2150 		    r->dst.neg, NULL, M_GETFIB(pd->m)))
2151 			r = r->skip[PF_SKIP_DST_ADDR];
2152 		else if (r->dst.port_op && !pf_match_port(r->dst.port_op,
2153 			    r->dst.port[0], r->dst.port[1], sh->dest_port))
2154 			r = r->skip[PF_SKIP_DST_PORT];
2155 		else {
2156 			rm = r;
2157 			break;
2158 		}
2159 	}
2160 
2161 	if (srs) {
2162 		/* With scrub rules present SCTP normalization happens only
2163 		 * if one of rules has matched and it's not a "no scrub" rule */
2164 		if (rm == NULL || rm->action == PF_NOSCRUB)
2165 			return (PF_PASS);
2166 
2167 		pf_counter_u64_critical_enter();
2168 		pf_counter_u64_add_protected(&r->packets[pd->dir == PF_OUT], 1);
2169 		pf_counter_u64_add_protected(&r->bytes[pd->dir == PF_OUT], pd->tot_len);
2170 		pf_counter_u64_critical_exit();
2171 	}
2172 
2173 	/* Verify we're a multiple of 4 bytes long */
2174 	if ((pd->tot_len - pd->off - sizeof(struct sctphdr)) % 4)
2175 		goto sctp_drop;
2176 
2177 	/* INIT chunk needs to be the only chunk */
2178 	if (pd->sctp_flags & PFDESC_SCTP_INIT)
2179 		if (pd->sctp_flags & ~PFDESC_SCTP_INIT)
2180 			goto sctp_drop;
2181 
2182 	return (PF_PASS);
2183 
2184 sctp_drop:
2185 	REASON_SET(&reason, PFRES_NORM);
2186 	if (rm != NULL && r->log)
2187 		PFLOG_PACKET(PF_DROP, reason, r, NULL, NULL, pd,
2188 		    1);
2189 
2190 	return (PF_DROP);
2191 }
2192 
2193 #if defined(INET) || defined(INET6)
2194 void
pf_scrub(struct pf_pdesc * pd)2195 pf_scrub(struct pf_pdesc *pd)
2196 {
2197 
2198 	struct ip		*h = mtod(pd->m, struct ip *);
2199 #ifdef INET6
2200 	struct ip6_hdr		*h6 = mtod(pd->m, struct ip6_hdr *);
2201 #endif
2202 
2203 	/* Clear IP_DF if no-df was requested */
2204 	if (pd->af == AF_INET && pd->act.flags & PFSTATE_NODF &&
2205 	    h->ip_off & htons(IP_DF))
2206 	{
2207 		u_int16_t ip_off = h->ip_off;
2208 
2209 		h->ip_off &= htons(~IP_DF);
2210 		h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_off, h->ip_off, 0);
2211 	}
2212 
2213 	/* Enforce a minimum ttl, may cause endless packet loops */
2214 	if (pd->af == AF_INET && pd->act.min_ttl &&
2215 	    h->ip_ttl < pd->act.min_ttl) {
2216 		u_int16_t ip_ttl = h->ip_ttl;
2217 
2218 		h->ip_ttl = pd->act.min_ttl;
2219 		h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_ttl, h->ip_ttl, 0);
2220 	}
2221 #ifdef INET6
2222 	/* Enforce a minimum ttl, may cause endless packet loops */
2223 	if (pd->af == AF_INET6 && pd->act.min_ttl &&
2224 	    h6->ip6_hlim < pd->act.min_ttl)
2225 		h6->ip6_hlim = pd->act.min_ttl;
2226 #endif
2227 	/* Enforce tos */
2228 	if (pd->act.flags & PFSTATE_SETTOS) {
2229 		switch (pd->af) {
2230 		case AF_INET: {
2231 			u_int16_t	ov, nv;
2232 
2233 			ov = *(u_int16_t *)h;
2234 			h->ip_tos = pd->act.set_tos | (h->ip_tos & IPTOS_ECN_MASK);
2235 			nv = *(u_int16_t *)h;
2236 
2237 			h->ip_sum = pf_cksum_fixup(h->ip_sum, ov, nv, 0);
2238 			break;
2239 		}
2240 #ifdef INET6
2241 		case AF_INET6:
2242 			h6->ip6_flow &= IPV6_FLOWLABEL_MASK | IPV6_VERSION_MASK;
2243 			h6->ip6_flow |= htonl((pd->act.set_tos | IPV6_ECN(h6)) << 20);
2244 			break;
2245 #endif
2246 		}
2247 	}
2248 
2249 	/* random-id, but not for fragments */
2250 #ifdef INET
2251 	if (pd->af == AF_INET &&
2252 	    pd->act.flags & PFSTATE_RANDOMID && !(h->ip_off & ~htons(IP_DF))) {
2253 		uint16_t ip_id = h->ip_id;
2254 
2255 		ip_fillid(h);
2256 		h->ip_sum = pf_cksum_fixup(h->ip_sum, ip_id, h->ip_id, 0);
2257 	}
2258 #endif
2259 }
2260 #endif
2261