xref: /freebsd/sys/netinet6/frag6.c (revision ad9f4e6351fb23ee81bc940638d20af3ca7c278d)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
5  * All rights reserved.
6  * Copyright (c) 2019 Netflix, Inc.
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  * 3. Neither the name of the project nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  *
32  *	$KAME: frag6.c,v 1.33 2002/01/07 11:34:48 kjc Exp $
33  */
34 
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
37 
38 #include "opt_rss.h"
39 
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/domain.h>
43 #include <sys/eventhandler.h>
44 #include <sys/hash.h>
45 #include <sys/kernel.h>
46 #include <sys/malloc.h>
47 #include <sys/mbuf.h>
48 #include <sys/protosw.h>
49 #include <sys/queue.h>
50 #include <sys/socket.h>
51 #include <sys/sysctl.h>
52 #include <sys/syslog.h>
53 
54 #include <net/if.h>
55 #include <net/if_var.h>
56 #include <net/if_private.h>
57 #include <net/netisr.h>
58 #include <net/route.h>
59 #include <net/vnet.h>
60 
61 #include <netinet/in.h>
62 #include <netinet/in_var.h>
63 #include <netinet/ip6.h>
64 #include <netinet6/ip6_var.h>
65 #include <netinet/icmp6.h>
66 #include <netinet/in_systm.h>	/* For ECN definitions. */
67 #include <netinet/ip.h>		/* For ECN definitions. */
68 
69 #ifdef MAC
70 #include <security/mac/mac_framework.h>
71 #endif
72 
73 /*
74  * A "big picture" of how IPv6 fragment queues are all linked together.
75  *
76  * struct ip6qbucket ip6qb[...];			hashed buckets
77  * ||||||||
78  * |
79  * +--- TAILQ(struct ip6q, packets) *q6;		tailq entries holding
80  *      ||||||||					fragmented packets
81  *      |						(1 per original packet)
82  *      |
83  *      +--- TAILQ(struct ip6asfrag, ip6q_frags) *af6;	tailq entries of IPv6
84  *           |                                   *ip6af;fragment packets
85  *           |						for one original packet
86  *           + *mbuf
87  */
88 
89 /* Reassembly headers are stored in hash buckets. */
90 #define	IP6REASS_NHASH_LOG2	10
91 #define	IP6REASS_NHASH		(1 << IP6REASS_NHASH_LOG2)
92 #define	IP6REASS_HMASK		(IP6REASS_NHASH - 1)
93 
94 TAILQ_HEAD(ip6qhead, ip6q);
95 struct ip6qbucket {
96 	struct ip6qhead	packets;
97 	struct mtx	lock;
98 	int		count;
99 };
100 
101 struct ip6asfrag {
102 	TAILQ_ENTRY(ip6asfrag) ip6af_tq;
103 	struct mbuf	*ip6af_m;
104 	int		ip6af_offset;	/* Offset in ip6af_m to next header. */
105 	int		ip6af_frglen;	/* Fragmentable part length. */
106 	int		ip6af_off;	/* Fragment offset. */
107 	bool		ip6af_mff;	/* More fragment bit in frag off. */
108 };
109 
110 static MALLOC_DEFINE(M_FRAG6, "frag6", "IPv6 fragment reassembly header");
111 
112 #ifdef VIMAGE
113 /* A flag to indicate if IPv6 fragmentation is initialized. */
114 VNET_DEFINE_STATIC(bool,		frag6_on);
115 #define	V_frag6_on			VNET(frag6_on)
116 #endif
117 
118 /* System wide (global) maximum and count of packets in reassembly queues. */
119 static int ip6_maxfrags;
120 static u_int __exclusive_cache_line frag6_nfrags;
121 
122 /* Maximum and current packets in per-VNET reassembly queue. */
123 VNET_DEFINE_STATIC(int,			ip6_maxfragpackets);
124 VNET_DEFINE_STATIC(volatile u_int,	frag6_nfragpackets);
125 #define	V_ip6_maxfragpackets		VNET(ip6_maxfragpackets)
126 #define	V_frag6_nfragpackets		VNET(frag6_nfragpackets)
127 
128 /* Maximum per-VNET reassembly timeout (milliseconds) */
129 VNET_DEFINE_STATIC(u_int,		ip6_fraglifetime) = IPV6_DEFFRAGTTL;
130 #define	V_ip6_fraglifetime		VNET(ip6_fraglifetime)
131 
132 /* Maximum per-VNET reassembly queues per bucket and fragments per packet. */
133 VNET_DEFINE_STATIC(int,			ip6_maxfragbucketsize);
134 VNET_DEFINE_STATIC(int,			ip6_maxfragsperpacket);
135 #define	V_ip6_maxfragbucketsize		VNET(ip6_maxfragbucketsize)
136 #define	V_ip6_maxfragsperpacket		VNET(ip6_maxfragsperpacket)
137 
138 /* Per-VNET reassembly queue buckets. */
139 VNET_DEFINE_STATIC(struct ip6qbucket,	ip6qb[IP6REASS_NHASH]);
140 VNET_DEFINE_STATIC(uint32_t,		ip6qb_hashseed);
141 #define	V_ip6qb				VNET(ip6qb)
142 #define	V_ip6qb_hashseed		VNET(ip6qb_hashseed)
143 
144 #define	IP6QB_LOCK(_b)		mtx_lock(&V_ip6qb[(_b)].lock)
145 #define	IP6QB_TRYLOCK(_b)	mtx_trylock(&V_ip6qb[(_b)].lock)
146 #define	IP6QB_LOCK_ASSERT(_b)	mtx_assert(&V_ip6qb[(_b)].lock, MA_OWNED)
147 #define	IP6QB_UNLOCK(_b)	mtx_unlock(&V_ip6qb[(_b)].lock)
148 #define	IP6QB_HEAD(_b)		(&V_ip6qb[(_b)].packets)
149 
150 /*
151  * By default, limit the number of IP6 fragments across all reassembly
152  * queues to  1/32 of the total number of mbuf clusters.
153  *
154  * Limit the total number of reassembly queues per VNET to the
155  * IP6 fragment limit, but ensure the limit will not allow any bucket
156  * to grow above 100 items. (The bucket limit is
157  * IP_MAXFRAGPACKETS / (IPREASS_NHASH / 2), so the 50 is the correct
158  * multiplier to reach a 100-item limit.)
159  * The 100-item limit was chosen as brief testing seems to show that
160  * this produces "reasonable" performance on some subset of systems
161  * under DoS attack.
162  */
163 #define	IP6_MAXFRAGS		(nmbclusters / 32)
164 #define	IP6_MAXFRAGPACKETS	(imin(IP6_MAXFRAGS, IP6REASS_NHASH * 50))
165 
166 /* Interval between periodic reassembly queue inspections */
167 #define	IP6_CALLOUT_INTERVAL_MS	500
168 
169 /*
170  * Sysctls and helper function.
171  */
172 SYSCTL_DECL(_net_inet6_ip6);
173 
174 SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, frag6_nfrags,
175 	CTLFLAG_RD, &frag6_nfrags, 0,
176 	"Global number of IPv6 fragments across all reassembly queues.");
177 
178 static void
179 frag6_set_bucketsize(void)
180 {
181 	int i;
182 
183 	if ((i = V_ip6_maxfragpackets) > 0)
184 		V_ip6_maxfragbucketsize = imax(i / (IP6REASS_NHASH / 2), 1);
185 }
186 
187 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGS, maxfrags,
188 	CTLFLAG_RW, &ip6_maxfrags, 0,
189 	"Maximum allowed number of outstanding IPv6 packet fragments. "
190 	"A value of 0 means no fragmented packets will be accepted, while "
191 	"a value of -1 means no limit");
192 
193 static int
194 sysctl_ip6_maxfragpackets(SYSCTL_HANDLER_ARGS)
195 {
196 	int error, val;
197 
198 	val = V_ip6_maxfragpackets;
199 	error = sysctl_handle_int(oidp, &val, 0, req);
200 	if (error != 0 || !req->newptr)
201 		return (error);
202 	V_ip6_maxfragpackets = val;
203 	frag6_set_bucketsize();
204 	return (0);
205 }
206 SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_MAXFRAGPACKETS, maxfragpackets,
207 	CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
208 	NULL, 0, sysctl_ip6_maxfragpackets, "I",
209 	"Default maximum number of outstanding fragmented IPv6 packets. "
210 	"A value of 0 means no fragmented packets will be accepted, while a "
211 	"a value of -1 means no limit");
212 SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, frag6_nfragpackets,
213 	CTLFLAG_VNET | CTLFLAG_RD,
214 	__DEVOLATILE(u_int *, &VNET_NAME(frag6_nfragpackets)), 0,
215 	"Per-VNET number of IPv6 fragments across all reassembly queues.");
216 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGSPERPACKET, maxfragsperpacket,
217 	CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragsperpacket), 0,
218 	"Maximum allowed number of fragments per packet");
219 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGBUCKETSIZE, maxfragbucketsize,
220 	CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragbucketsize), 0,
221 	"Maximum number of reassembly queues per hash bucket");
222 
223 static int
224 frag6_milli_to_callout_ticks(int ms)
225 {
226 	return (ms / IP6_CALLOUT_INTERVAL_MS);
227 }
228 
229 static int
230 frag6_callout_ticks_to_milli(int ms)
231 {
232 	return (ms * IP6_CALLOUT_INTERVAL_MS);
233 }
234 
235 _Static_assert(sizeof(((struct ip6q *)NULL)->ip6q_ttl) >= 2,
236     "ip6q_ttl field is not large enough");
237 
238 static int
239 sysctl_ip6_fraglifetime(SYSCTL_HANDLER_ARGS)
240 {
241 	int error, val;
242 
243 	val = V_ip6_fraglifetime;
244 	error = sysctl_handle_int(oidp, &val, 0, req);
245 	if (error != 0 || !req->newptr)
246 		return (error);
247 	if (val <= 0)
248 		val = IPV6_DEFFRAGTTL;
249 
250 	if (frag6_milli_to_callout_ticks(val) >= 65536)
251 		val = frag6_callout_ticks_to_milli(65535);
252 #ifdef VIMAGE
253 	if (!IS_DEFAULT_VNET(curvnet)) {
254 		CURVNET_SET(vnet0);
255 		int host_val = V_ip6_fraglifetime;
256 		CURVNET_RESTORE();
257 
258 		if (val > host_val)
259 			val = host_val;
260 	}
261 #endif
262 	V_ip6_fraglifetime = val;
263 	return (0);
264 }
265 SYSCTL_PROC(_net_inet6_ip6, OID_AUTO, fraglifetime_ms,
266 	CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
267 	NULL, 0, sysctl_ip6_fraglifetime, "I",
268 	"Fragment lifetime, in milliseconds");
269 
270 /*
271  * Remove the IPv6 fragmentation header from the mbuf.
272  */
273 int
274 ip6_deletefraghdr(struct mbuf *m, int offset, int wait __unused)
275 {
276 	struct ip6_hdr *ip6;
277 
278 	KASSERT(m->m_len >= offset + sizeof(struct ip6_frag),
279 	    ("%s: ext headers not contigous in mbuf %p m_len %d >= "
280 	    "offset %d + %zu\n", __func__, m, m->m_len, offset,
281 	    sizeof(struct ip6_frag)));
282 
283 	/* Delete frag6 header. */
284 	ip6 = mtod(m, struct ip6_hdr *);
285 	bcopy(ip6, (char *)ip6 + sizeof(struct ip6_frag), offset);
286 	m->m_data += sizeof(struct ip6_frag);
287 	m->m_len -= sizeof(struct ip6_frag);
288 	m->m_flags |= M_FRAGMENTED;
289 
290 	return (0);
291 }
292 
293 /*
294  * Free a fragment reassembly header and all associated datagrams.
295  */
296 static void
297 frag6_freef(struct ip6q *q6, uint32_t bucket)
298 {
299 	struct ip6_hdr *ip6;
300 	struct ip6asfrag *af6;
301 	struct mbuf *m;
302 
303 	IP6QB_LOCK_ASSERT(bucket);
304 
305 	while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) {
306 		m = af6->ip6af_m;
307 		TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq);
308 
309 		/*
310 		 * Return ICMP time exceeded error for the 1st fragment.
311 		 * Just free other fragments.
312 		 */
313 		if (af6->ip6af_off == 0 && m->m_pkthdr.rcvif != NULL) {
314 			/* Adjust pointer. */
315 			ip6 = mtod(m, struct ip6_hdr *);
316 
317 			/* Restore source and destination addresses. */
318 			ip6->ip6_src = q6->ip6q_src;
319 			ip6->ip6_dst = q6->ip6q_dst;
320 
321 			icmp6_error(m, ICMP6_TIME_EXCEEDED,
322 			    ICMP6_TIME_EXCEED_REASSEMBLY, 0);
323 		} else
324 			m_freem(m);
325 
326 		free(af6, M_FRAG6);
327 	}
328 
329 	TAILQ_REMOVE(IP6QB_HEAD(bucket), q6, ip6q_tq);
330 	V_ip6qb[bucket].count--;
331 	atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag);
332 #ifdef MAC
333 	mac_ip6q_destroy(q6);
334 #endif
335 	free(q6, M_FRAG6);
336 	atomic_subtract_int(&V_frag6_nfragpackets, 1);
337 }
338 
339 /*
340  * Drain off all datagram fragments belonging to
341  * the given network interface.
342  */
343 static void
344 frag6_cleanup(void *arg __unused, struct ifnet *ifp)
345 {
346 	struct ip6qhead *head;
347 	struct ip6q *q6;
348 	struct ip6asfrag *af6;
349 	uint32_t bucket;
350 
351 	KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__));
352 
353 	CURVNET_SET_QUIET(ifp->if_vnet);
354 #ifdef VIMAGE
355 	/*
356 	 * Skip processing if IPv6 reassembly is not initialised or
357 	 * torn down by frag6_destroy().
358 	 */
359 	if (!V_frag6_on) {
360 		CURVNET_RESTORE();
361 		return;
362 	}
363 #endif
364 
365 	for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
366 		IP6QB_LOCK(bucket);
367 		head = IP6QB_HEAD(bucket);
368 		/* Scan fragment list. */
369 		TAILQ_FOREACH(q6, head, ip6q_tq) {
370 			TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) {
371 				/* Clear no longer valid rcvif pointer. */
372 				if (af6->ip6af_m->m_pkthdr.rcvif == ifp)
373 					af6->ip6af_m->m_pkthdr.rcvif = NULL;
374 			}
375 		}
376 		IP6QB_UNLOCK(bucket);
377 	}
378 	CURVNET_RESTORE();
379 }
380 EVENTHANDLER_DEFINE(ifnet_departure_event, frag6_cleanup, NULL, 0);
381 
382 /*
383  * Like in RFC2460, in RFC8200, fragment and reassembly rules do not agree with
384  * each other, in terms of next header field handling in fragment header.
385  * While the sender will use the same value for all of the fragmented packets,
386  * receiver is suggested not to check for consistency.
387  *
388  * Fragment rules (p18,p19):
389  *	(2)  A Fragment header containing:
390  *	The Next Header value that identifies the first header
391  *	after the Per-Fragment headers of the original packet.
392  *		-> next header field is same for all fragments
393  *
394  * Reassembly rule (p20):
395  *	The Next Header field of the last header of the Per-Fragment
396  *	headers is obtained from the Next Header field of the first
397  *	fragment's Fragment header.
398  *		-> should grab it from the first fragment only
399  *
400  * The following note also contradicts with fragment rule - no one is going to
401  * send different fragment with different next header field.
402  *
403  * Additional note (p22) [not an error]:
404  *	The Next Header values in the Fragment headers of different
405  *	fragments of the same original packet may differ.  Only the value
406  *	from the Offset zero fragment packet is used for reassembly.
407  *		-> should grab it from the first fragment only
408  *
409  * There is no explicit reason given in the RFC.  Historical reason maybe?
410  */
411 /*
412  * Fragment input.
413  */
414 int
415 frag6_input(struct mbuf **mp, int *offp, int proto)
416 {
417 	struct mbuf *m, *t;
418 	struct ip6_hdr *ip6;
419 	struct ip6_frag *ip6f;
420 	struct ip6qhead *head;
421 	struct ip6q *q6;
422 	struct ip6asfrag *af6, *ip6af, *af6tmp;
423 	struct in6_ifaddr *ia6;
424 	struct ifnet *dstifp, *srcifp;
425 	uint32_t hashkey[(sizeof(struct in6_addr) * 2 +
426 		    sizeof(ip6f->ip6f_ident)) / sizeof(uint32_t)];
427 	uint32_t bucket, *hashkeyp;
428 	int fragoff, frgpartlen;	/* Must be larger than uint16_t. */
429 	int nxt, offset, plen;
430 	uint8_t ecn, ecn0;
431 	bool only_frag;
432 #ifdef RSS
433 	struct ip6_direct_ctx *ip6dc;
434 	struct m_tag *mtag;
435 #endif
436 
437 	m = *mp;
438 	offset = *offp;
439 
440 	M_ASSERTPKTHDR(m);
441 
442 	if (m->m_len < offset + sizeof(struct ip6_frag)) {
443 		m = m_pullup(m, offset + sizeof(struct ip6_frag));
444 		if (m == NULL) {
445 			IP6STAT_INC(ip6s_exthdrtoolong);
446 			*mp = NULL;
447 			return (IPPROTO_DONE);
448 		}
449 	}
450 	ip6 = mtod(m, struct ip6_hdr *);
451 
452 	dstifp = NULL;
453 	/* Find the destination interface of the packet. */
454 	ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false);
455 	if (ia6 != NULL)
456 		dstifp = ia6->ia_ifp;
457 
458 	/* Jumbo payload cannot contain a fragment header. */
459 	if (ip6->ip6_plen == 0) {
460 		icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
461 		in6_ifstat_inc(dstifp, ifs6_reass_fail);
462 		*mp = NULL;
463 		return (IPPROTO_DONE);
464 	}
465 
466 	/*
467 	 * Check whether fragment packet's fragment length is a
468 	 * multiple of 8 octets (unless it is the last one).
469 	 * sizeof(struct ip6_frag) == 8
470 	 * sizeof(struct ip6_hdr) = 40
471 	 */
472 	ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
473 	if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
474 	    (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
475 		icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
476 		    offsetof(struct ip6_hdr, ip6_plen));
477 		in6_ifstat_inc(dstifp, ifs6_reass_fail);
478 		*mp = NULL;
479 		return (IPPROTO_DONE);
480 	}
481 
482 	IP6STAT_INC(ip6s_fragments);
483 	in6_ifstat_inc(dstifp, ifs6_reass_reqd);
484 
485 	/*
486 	 * Handle "atomic" fragments (offset and m bit set to 0) upfront,
487 	 * unrelated to any reassembly.  We need to remove the frag hdr
488 	 * which is ugly.
489 	 * See RFC 6946 and section 4.5 of RFC 8200.
490 	 */
491 	if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) {
492 		IP6STAT_INC(ip6s_atomicfrags);
493 		nxt = ip6f->ip6f_nxt;
494 		/*
495 		 * Set nxt(-hdr field value) to the original value.
496 		 * We cannot just set ip6->ip6_nxt as there might be
497 		 * an unfragmentable part with extension headers and
498 		 * we must update the last one.
499 		 */
500 		m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t),
501 		    (caddr_t)&nxt);
502 		ip6->ip6_plen = htons(ntohs(ip6->ip6_plen) -
503 		    sizeof(struct ip6_frag));
504 		if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0)
505 			goto dropfrag2;
506 		m->m_pkthdr.len -= sizeof(struct ip6_frag);
507 		in6_ifstat_inc(dstifp, ifs6_reass_ok);
508 		*mp = m;
509 		return (nxt);
510 	}
511 
512 	/* Offset now points to data portion. */
513 	offset += sizeof(struct ip6_frag);
514 
515 	/* Get fragment length and discard 0-byte fragments. */
516 	frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
517 	if (frgpartlen == 0) {
518 		icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
519 		    offsetof(struct ip6_hdr, ip6_plen));
520 		in6_ifstat_inc(dstifp, ifs6_reass_fail);
521 		IP6STAT_INC(ip6s_fragdropped);
522 		*mp = NULL;
523 		return (IPPROTO_DONE);
524 	}
525 
526 	/*
527 	 * Enforce upper bound on number of fragments for the entire system.
528 	 * If maxfrag is 0, never accept fragments.
529 	 * If maxfrag is -1, accept all fragments without limitation.
530 	 */
531 	if (ip6_maxfrags < 0)
532 		;
533 	else if (atomic_load_int(&frag6_nfrags) >= (u_int)ip6_maxfrags)
534 		goto dropfrag2;
535 
536 	/*
537 	 * Validate that a full header chain to the ULP is present in the
538 	 * packet containing the first fragment as per RFC RFC7112 and
539 	 * RFC 8200 pages 18,19:
540 	 * The first fragment packet is composed of:
541 	 * (3)  Extension headers, if any, and the Upper-Layer header.  These
542 	 *      headers must be in the first fragment.  ...
543 	 */
544 	fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
545 	/* XXX TODO.  thj has D16851 open for this. */
546 	/* Send ICMPv6 4,3 in case of violation. */
547 
548 	/* Store receive network interface pointer for later. */
549 	srcifp = m->m_pkthdr.rcvif;
550 
551 	/* Generate a hash value for fragment bucket selection. */
552 	hashkeyp = hashkey;
553 	memcpy(hashkeyp, &ip6->ip6_src, sizeof(struct in6_addr));
554 	hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp);
555 	memcpy(hashkeyp, &ip6->ip6_dst, sizeof(struct in6_addr));
556 	hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp);
557 	*hashkeyp = ip6f->ip6f_ident;
558 	bucket = jenkins_hash32(hashkey, nitems(hashkey), V_ip6qb_hashseed);
559 	bucket &= IP6REASS_HMASK;
560 	IP6QB_LOCK(bucket);
561 	head = IP6QB_HEAD(bucket);
562 
563 	TAILQ_FOREACH(q6, head, ip6q_tq)
564 		if (ip6f->ip6f_ident == q6->ip6q_ident &&
565 		    IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
566 		    IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst)
567 #ifdef MAC
568 		    && mac_ip6q_match(m, q6)
569 #endif
570 		    )
571 			break;
572 
573 	only_frag = false;
574 	if (q6 == NULL) {
575 		/* A first fragment to arrive creates a reassembly queue. */
576 		only_frag = true;
577 
578 		/*
579 		 * Enforce upper bound on number of fragmented packets
580 		 * for which we attempt reassembly;
581 		 * If maxfragpackets is 0, never accept fragments.
582 		 * If maxfragpackets is -1, accept all fragments without
583 		 * limitation.
584 		 */
585 		if (V_ip6_maxfragpackets < 0)
586 			;
587 		else if (V_ip6qb[bucket].count >= V_ip6_maxfragbucketsize ||
588 		    atomic_load_int(&V_frag6_nfragpackets) >=
589 		    (u_int)V_ip6_maxfragpackets)
590 			goto dropfrag;
591 
592 		/* Allocate IPv6 fragement packet queue entry. */
593 		q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FRAG6,
594 		    M_NOWAIT | M_ZERO);
595 		if (q6 == NULL)
596 			goto dropfrag;
597 #ifdef MAC
598 		if (mac_ip6q_init(q6, M_NOWAIT) != 0) {
599 			free(q6, M_FRAG6);
600 			goto dropfrag;
601 		}
602 		mac_ip6q_create(m, q6);
603 #endif
604 		atomic_add_int(&V_frag6_nfragpackets, 1);
605 
606 		/* ip6q_nxt will be filled afterwards, from 1st fragment. */
607 		TAILQ_INIT(&q6->ip6q_frags);
608 		q6->ip6q_ident	= ip6f->ip6f_ident;
609 		q6->ip6q_ttl	= frag6_milli_to_callout_ticks(V_ip6_fraglifetime);
610 		q6->ip6q_src	= ip6->ip6_src;
611 		q6->ip6q_dst	= ip6->ip6_dst;
612 		q6->ip6q_ecn	= IPV6_ECN(ip6);
613 		q6->ip6q_unfrglen = -1;	/* The 1st fragment has not arrived. */
614 
615 		/* Add the fragemented packet to the bucket. */
616 		TAILQ_INSERT_HEAD(head, q6, ip6q_tq);
617 		V_ip6qb[bucket].count++;
618 	}
619 
620 	/*
621 	 * If it is the 1st fragment, record the length of the
622 	 * unfragmentable part and the next header of the fragment header.
623 	 * Assume the first 1st fragement to arrive will be correct.
624 	 * We do not have any duplicate checks here yet so another packet
625 	 * with fragoff == 0 could come and overwrite the ip6q_unfrglen
626 	 * and worse, the next header, at any time.
627 	 */
628 	if (fragoff == 0 && q6->ip6q_unfrglen == -1) {
629 		q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) -
630 		    sizeof(struct ip6_frag);
631 		q6->ip6q_nxt = ip6f->ip6f_nxt;
632 		/* XXX ECN? */
633 	}
634 
635 	/*
636 	 * Check that the reassembled packet would not exceed 65535 bytes
637 	 * in size.
638 	 * If it would exceed, discard the fragment and return an ICMP error.
639 	 */
640 	if (q6->ip6q_unfrglen >= 0) {
641 		/* The 1st fragment has already arrived. */
642 		if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
643 			if (only_frag) {
644 				TAILQ_REMOVE(head, q6, ip6q_tq);
645 				V_ip6qb[bucket].count--;
646 				atomic_subtract_int(&V_frag6_nfragpackets, 1);
647 #ifdef MAC
648 				mac_ip6q_destroy(q6);
649 #endif
650 				free(q6, M_FRAG6);
651 			}
652 			IP6QB_UNLOCK(bucket);
653 			icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
654 			    offset - sizeof(struct ip6_frag) +
655 			    offsetof(struct ip6_frag, ip6f_offlg));
656 			*mp = NULL;
657 			return (IPPROTO_DONE);
658 		}
659 	} else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
660 		if (only_frag) {
661 			TAILQ_REMOVE(head, q6, ip6q_tq);
662 			V_ip6qb[bucket].count--;
663 			atomic_subtract_int(&V_frag6_nfragpackets, 1);
664 #ifdef MAC
665 			mac_ip6q_destroy(q6);
666 #endif
667 			free(q6, M_FRAG6);
668 		}
669 		IP6QB_UNLOCK(bucket);
670 		icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
671 		    offset - sizeof(struct ip6_frag) +
672 		    offsetof(struct ip6_frag, ip6f_offlg));
673 		*mp = NULL;
674 		return (IPPROTO_DONE);
675 	}
676 
677 	/*
678 	 * If it is the first fragment, do the above check for each
679 	 * fragment already stored in the reassembly queue.
680 	 */
681 	if (fragoff == 0 && !only_frag) {
682 		TAILQ_FOREACH_SAFE(af6, &q6->ip6q_frags, ip6af_tq, af6tmp) {
683 			if (q6->ip6q_unfrglen + af6->ip6af_off +
684 			    af6->ip6af_frglen > IPV6_MAXPACKET) {
685 				struct ip6_hdr *ip6err;
686 				struct mbuf *merr;
687 				int erroff;
688 
689 				merr = af6->ip6af_m;
690 				erroff = af6->ip6af_offset;
691 
692 				/* Dequeue the fragment. */
693 				TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq);
694 				q6->ip6q_nfrag--;
695 				atomic_subtract_int(&frag6_nfrags, 1);
696 				free(af6, M_FRAG6);
697 
698 				/* Set a valid receive interface pointer. */
699 				merr->m_pkthdr.rcvif = srcifp;
700 
701 				/* Adjust pointer. */
702 				ip6err = mtod(merr, struct ip6_hdr *);
703 
704 				/*
705 				 * Restore source and destination addresses
706 				 * in the erroneous IPv6 header.
707 				 */
708 				ip6err->ip6_src = q6->ip6q_src;
709 				ip6err->ip6_dst = q6->ip6q_dst;
710 
711 				icmp6_error(merr, ICMP6_PARAM_PROB,
712 				    ICMP6_PARAMPROB_HEADER,
713 				    erroff - sizeof(struct ip6_frag) +
714 				    offsetof(struct ip6_frag, ip6f_offlg));
715 			}
716 		}
717 	}
718 
719 	/* Allocate an IPv6 fragement queue entry for this fragmented part. */
720 	ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FRAG6,
721 	    M_NOWAIT | M_ZERO);
722 	if (ip6af == NULL)
723 		goto dropfrag;
724 	ip6af->ip6af_mff = (ip6f->ip6f_offlg & IP6F_MORE_FRAG) ? true : false;
725 	ip6af->ip6af_off = fragoff;
726 	ip6af->ip6af_frglen = frgpartlen;
727 	ip6af->ip6af_offset = offset;
728 	ip6af->ip6af_m = m;
729 
730 	if (only_frag) {
731 		/*
732 		 * Do a manual insert rather than a hard-to-understand cast
733 		 * to a different type relying on data structure order to work.
734 		 */
735 		TAILQ_INSERT_HEAD(&q6->ip6q_frags, ip6af, ip6af_tq);
736 		goto postinsert;
737 	}
738 
739 	/* Do duplicate, condition, and boundry checks. */
740 	/*
741 	 * Handle ECN by comparing this segment with the first one;
742 	 * if CE is set, do not lose CE.
743 	 * Drop if CE and not-ECT are mixed for the same packet.
744 	 */
745 	ecn = IPV6_ECN(ip6);
746 	ecn0 = q6->ip6q_ecn;
747 	if (ecn == IPTOS_ECN_CE) {
748 		if (ecn0 == IPTOS_ECN_NOTECT) {
749 			free(ip6af, M_FRAG6);
750 			goto dropfrag;
751 		}
752 		if (ecn0 != IPTOS_ECN_CE)
753 			q6->ip6q_ecn = IPTOS_ECN_CE;
754 	}
755 	if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) {
756 		free(ip6af, M_FRAG6);
757 		goto dropfrag;
758 	}
759 
760 	/* Find a fragmented part which begins after this one does. */
761 	TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq)
762 		if (af6->ip6af_off > ip6af->ip6af_off)
763 			break;
764 
765 	/*
766 	 * If the incoming framgent overlaps some existing fragments in
767 	 * the reassembly queue, drop both the new fragment and the
768 	 * entire reassembly queue.  However, if the new fragment
769 	 * is an exact duplicate of an existing fragment, only silently
770 	 * drop the existing fragment and leave the fragmentation queue
771 	 * unchanged, as allowed by the RFC.  (RFC 8200, 4.5)
772 	 */
773 	if (af6 != NULL)
774 		af6tmp = TAILQ_PREV(af6, ip6fraghead, ip6af_tq);
775 	else
776 		af6tmp = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead);
777 	if (af6tmp != NULL) {
778 		if (af6tmp->ip6af_off + af6tmp->ip6af_frglen -
779 		    ip6af->ip6af_off > 0) {
780 			if (af6tmp->ip6af_off != ip6af->ip6af_off ||
781 			    af6tmp->ip6af_frglen != ip6af->ip6af_frglen)
782 				frag6_freef(q6, bucket);
783 			free(ip6af, M_FRAG6);
784 			goto dropfrag;
785 		}
786 	}
787 	if (af6 != NULL) {
788 		if (ip6af->ip6af_off + ip6af->ip6af_frglen -
789 		    af6->ip6af_off > 0) {
790 			if (af6->ip6af_off != ip6af->ip6af_off ||
791 			    af6->ip6af_frglen != ip6af->ip6af_frglen)
792 				frag6_freef(q6, bucket);
793 			free(ip6af, M_FRAG6);
794 			goto dropfrag;
795 		}
796 	}
797 
798 #ifdef MAC
799 	mac_ip6q_update(m, q6);
800 #endif
801 
802 	/*
803 	 * Stick new segment in its place; check for complete reassembly.
804 	 * If not complete, check fragment limit.  Move to front of packet
805 	 * queue, as we are the most recently active fragmented packet.
806 	 */
807 	if (af6 != NULL)
808 		TAILQ_INSERT_BEFORE(af6, ip6af, ip6af_tq);
809 	else
810 		TAILQ_INSERT_TAIL(&q6->ip6q_frags, ip6af, ip6af_tq);
811 postinsert:
812 	atomic_add_int(&frag6_nfrags, 1);
813 	q6->ip6q_nfrag++;
814 
815 	plen = 0;
816 	TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) {
817 		if (af6->ip6af_off != plen) {
818 			if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) {
819 				IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag);
820 				frag6_freef(q6, bucket);
821 			}
822 			IP6QB_UNLOCK(bucket);
823 			*mp = NULL;
824 			return (IPPROTO_DONE);
825 		}
826 		plen += af6->ip6af_frglen;
827 	}
828 	af6 = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead);
829 	if (af6->ip6af_mff) {
830 		if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) {
831 			IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag);
832 			frag6_freef(q6, bucket);
833 		}
834 		IP6QB_UNLOCK(bucket);
835 		*mp = NULL;
836 		return (IPPROTO_DONE);
837 	}
838 
839 	/* Reassembly is complete; concatenate fragments. */
840 	ip6af = TAILQ_FIRST(&q6->ip6q_frags);
841 	t = m = ip6af->ip6af_m;
842 	TAILQ_REMOVE(&q6->ip6q_frags, ip6af, ip6af_tq);
843 	while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) {
844 		m->m_pkthdr.csum_flags &=
845 		    af6->ip6af_m->m_pkthdr.csum_flags;
846 		m->m_pkthdr.csum_data +=
847 		    af6->ip6af_m->m_pkthdr.csum_data;
848 
849 		TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq);
850 		t = m_last(t);
851 		m_adj(af6->ip6af_m, af6->ip6af_offset);
852 		m_demote_pkthdr(af6->ip6af_m);
853 		m_cat(t, af6->ip6af_m);
854 		free(af6, M_FRAG6);
855 	}
856 
857 	while (m->m_pkthdr.csum_data & 0xffff0000)
858 		m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) +
859 		    (m->m_pkthdr.csum_data >> 16);
860 
861 	/* Adjust offset to point where the original next header starts. */
862 	offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
863 	free(ip6af, M_FRAG6);
864 	ip6 = mtod(m, struct ip6_hdr *);
865 	ip6->ip6_plen = htons((u_short)plen + offset - sizeof(struct ip6_hdr));
866 	if (q6->ip6q_ecn == IPTOS_ECN_CE)
867 		ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20);
868 	nxt = q6->ip6q_nxt;
869 
870 	TAILQ_REMOVE(head, q6, ip6q_tq);
871 	V_ip6qb[bucket].count--;
872 	atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag);
873 
874 	ip6_deletefraghdr(m, offset, M_NOWAIT);
875 
876 	/* Set nxt(-hdr field value) to the original value. */
877 	m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t),
878 	    (caddr_t)&nxt);
879 
880 #ifdef MAC
881 	mac_ip6q_reassemble(q6, m);
882 	mac_ip6q_destroy(q6);
883 #endif
884 	free(q6, M_FRAG6);
885 	atomic_subtract_int(&V_frag6_nfragpackets, 1);
886 
887 	if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
888 
889 		plen = 0;
890 		for (t = m; t; t = t->m_next)
891 			plen += t->m_len;
892 		m->m_pkthdr.len = plen;
893 		/* Set a valid receive interface pointer. */
894 		m->m_pkthdr.rcvif = srcifp;
895 	}
896 
897 #ifdef RSS
898 	mtag = m_tag_alloc(MTAG_ABI_IPV6, IPV6_TAG_DIRECT, sizeof(*ip6dc),
899 	    M_NOWAIT);
900 	if (mtag == NULL)
901 		goto dropfrag;
902 
903 	ip6dc = (struct ip6_direct_ctx *)(mtag + 1);
904 	ip6dc->ip6dc_nxt = nxt;
905 	ip6dc->ip6dc_off = offset;
906 
907 	m_tag_prepend(m, mtag);
908 #endif
909 
910 	IP6QB_UNLOCK(bucket);
911 	IP6STAT_INC(ip6s_reassembled);
912 	in6_ifstat_inc(dstifp, ifs6_reass_ok);
913 
914 #ifdef RSS
915 	/* Queue/dispatch for reprocessing. */
916 	netisr_dispatch(NETISR_IPV6_DIRECT, m);
917 	*mp = NULL;
918 	return (IPPROTO_DONE);
919 #endif
920 
921 	/* Tell launch routine the next header. */
922 	*mp = m;
923 	*offp = offset;
924 
925 	return (nxt);
926 
927 dropfrag:
928 	IP6QB_UNLOCK(bucket);
929 dropfrag2:
930 	in6_ifstat_inc(dstifp, ifs6_reass_fail);
931 	IP6STAT_INC(ip6s_fragdropped);
932 	m_freem(m);
933 	*mp = NULL;
934 	return (IPPROTO_DONE);
935 }
936 
937 /*
938  * IPv6 reassembling timer processing;
939  * if a timer expires on a reassembly queue, discard it.
940  */
941 static struct callout frag6_callout;
942 static void
943 frag6_slowtimo(void *arg __unused)
944 {
945 	VNET_ITERATOR_DECL(vnet_iter);
946 	struct ip6qhead *head;
947 	struct ip6q *q6, *q6tmp;
948 	uint32_t bucket;
949 
950 	if (atomic_load_int(&frag6_nfrags) == 0)
951 		goto done;
952 
953 	VNET_LIST_RLOCK_NOSLEEP();
954 	VNET_FOREACH(vnet_iter) {
955 		CURVNET_SET(vnet_iter);
956 		for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
957 			if (V_ip6qb[bucket].count == 0)
958 				continue;
959 			IP6QB_LOCK(bucket);
960 			head = IP6QB_HEAD(bucket);
961 			TAILQ_FOREACH_SAFE(q6, head, ip6q_tq, q6tmp)
962 				if (--q6->ip6q_ttl == 0) {
963 					IP6STAT_ADD(ip6s_fragtimeout,
964 						q6->ip6q_nfrag);
965 					/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
966 					frag6_freef(q6, bucket);
967 				}
968 			/*
969 			 * If we are over the maximum number of fragments
970 			 * (due to the limit being lowered), drain off
971 			 * enough to get down to the new limit.
972 			 * Note that we drain all reassembly queues if
973 			 * maxfragpackets is 0 (fragmentation is disabled),
974 			 * and do not enforce a limit when maxfragpackets
975 			 * is negative.
976 			 */
977 			while ((V_ip6_maxfragpackets == 0 ||
978 			    (V_ip6_maxfragpackets > 0 &&
979 			    V_ip6qb[bucket].count > V_ip6_maxfragbucketsize)) &&
980 			    (q6 = TAILQ_LAST(head, ip6qhead)) != NULL) {
981 				IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag);
982 				/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
983 				frag6_freef(q6, bucket);
984 			}
985 			IP6QB_UNLOCK(bucket);
986 		}
987 		/*
988 		 * If we are still over the maximum number of fragmented
989 		 * packets, drain off enough to get down to the new limit.
990 		 */
991 		bucket = 0;
992 		while (V_ip6_maxfragpackets >= 0 &&
993 		    atomic_load_int(&V_frag6_nfragpackets) >
994 		    (u_int)V_ip6_maxfragpackets) {
995 			IP6QB_LOCK(bucket);
996 			q6 = TAILQ_LAST(IP6QB_HEAD(bucket), ip6qhead);
997 			if (q6 != NULL) {
998 				IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag);
999 				/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
1000 				frag6_freef(q6, bucket);
1001 			}
1002 			IP6QB_UNLOCK(bucket);
1003 			bucket = (bucket + 1) % IP6REASS_NHASH;
1004 		}
1005 		CURVNET_RESTORE();
1006 	}
1007 	VNET_LIST_RUNLOCK_NOSLEEP();
1008 done:
1009 	callout_reset_sbt(&frag6_callout, SBT_1MS * IP6_CALLOUT_INTERVAL_MS,
1010 	    SBT_1MS * 10, frag6_slowtimo, NULL, 0);
1011 }
1012 
1013 static void
1014 frag6_slowtimo_init(void *arg __unused)
1015 {
1016 
1017 	callout_init(&frag6_callout, 1);
1018 	callout_reset_sbt(&frag6_callout, SBT_1MS * IP6_CALLOUT_INTERVAL_MS,
1019 	    SBT_1MS * 10, frag6_slowtimo, NULL, 0);
1020 }
1021 SYSINIT(frag6, SI_SUB_VNET_DONE, SI_ORDER_ANY, frag6_slowtimo_init, NULL);
1022 
1023 /*
1024  * Eventhandler to adjust limits in case nmbclusters change.
1025  */
1026 static void
1027 frag6_change(void *tag)
1028 {
1029 	VNET_ITERATOR_DECL(vnet_iter);
1030 
1031 	ip6_maxfrags = IP6_MAXFRAGS;
1032 	VNET_LIST_RLOCK_NOSLEEP();
1033 	VNET_FOREACH(vnet_iter) {
1034 		CURVNET_SET(vnet_iter);
1035 		V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS;
1036 		frag6_set_bucketsize();
1037 		CURVNET_RESTORE();
1038 	}
1039 	VNET_LIST_RUNLOCK_NOSLEEP();
1040 }
1041 
1042 /*
1043  * Initialise reassembly queue and fragment identifier.
1044  */
1045 void
1046 frag6_init(void)
1047 {
1048 	uint32_t bucket;
1049 
1050 	V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS;
1051 	frag6_set_bucketsize();
1052 	for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
1053 		TAILQ_INIT(IP6QB_HEAD(bucket));
1054 		mtx_init(&V_ip6qb[bucket].lock, "ip6qb", NULL, MTX_DEF);
1055 		V_ip6qb[bucket].count = 0;
1056 	}
1057 	V_ip6qb_hashseed = arc4random();
1058 	V_ip6_maxfragsperpacket = 64;
1059 #ifdef VIMAGE
1060 	V_frag6_on = true;
1061 #endif
1062 	if (!IS_DEFAULT_VNET(curvnet))
1063 		return;
1064 
1065 	ip6_maxfrags = IP6_MAXFRAGS;
1066 	EVENTHANDLER_REGISTER(nmbclusters_change,
1067 	    frag6_change, NULL, EVENTHANDLER_PRI_ANY);
1068 }
1069 
1070 /*
1071  * Drain off all datagram fragments.
1072  */
1073 static void
1074 frag6_drain_one(void)
1075 {
1076 	struct ip6q *q6;
1077 	uint32_t bucket;
1078 
1079 	for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
1080 		IP6QB_LOCK(bucket);
1081 		while ((q6 = TAILQ_FIRST(IP6QB_HEAD(bucket))) != NULL) {
1082 			IP6STAT_INC(ip6s_fragdropped);
1083 			/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
1084 			frag6_freef(q6, bucket);
1085 		}
1086 		IP6QB_UNLOCK(bucket);
1087 	}
1088 }
1089 
1090 void
1091 frag6_drain(void)
1092 {
1093 	VNET_ITERATOR_DECL(vnet_iter);
1094 
1095 	VNET_LIST_RLOCK_NOSLEEP();
1096 	VNET_FOREACH(vnet_iter) {
1097 		CURVNET_SET(vnet_iter);
1098 		frag6_drain_one();
1099 		CURVNET_RESTORE();
1100 	}
1101 	VNET_LIST_RUNLOCK_NOSLEEP();
1102 }
1103 
1104 #ifdef VIMAGE
1105 /*
1106  * Clear up IPv6 reassembly structures.
1107  */
1108 void
1109 frag6_destroy(void)
1110 {
1111 	uint32_t bucket;
1112 
1113 	frag6_drain_one();
1114 	V_frag6_on = false;
1115 	for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
1116 		KASSERT(V_ip6qb[bucket].count == 0,
1117 		    ("%s: V_ip6qb[%d] (%p) count not 0 (%d)", __func__,
1118 		    bucket, &V_ip6qb[bucket], V_ip6qb[bucket].count));
1119 		mtx_destroy(&V_ip6qb[bucket].lock);
1120 	}
1121 }
1122 #endif
1123