2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
6 * Copyright (c) 2019 Netflix, Inc.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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.
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
32 * $KAME: frag6.c,v 1.33 2002/01/07 11:34:48 kjc Exp $
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/domain.h>
43 #include <sys/eventhandler.h>
45 #include <sys/kernel.h>
46 #include <sys/malloc.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>
55 #include <net/if_var.h>
56 #include <net/netisr.h>
57 #include <net/route.h>
60 #include <netinet/in.h>
61 #include <netinet/in_var.h>
62 #include <netinet/ip6.h>
63 #include <netinet6/ip6_var.h>
64 #include <netinet/icmp6.h>
65 #include <netinet/in_systm.h> /* For ECN definitions. */
66 #include <netinet/ip.h> /* For ECN definitions. */
69 #include <security/mac/mac_framework.h>
73 * A "big picture" of how IPv6 fragment queues are all linked together.
75 * struct ip6qbucket ip6qb[...]; hashed buckets
78 * +--- TAILQ(struct ip6q, packets) *q6; tailq entries holding
79 * |||||||| fragmented packets
80 * | (1 per original packet)
82 * +--- TAILQ(struct ip6asfrag, ip6q_frags) *af6; tailq entries of IPv6
83 * | *ip6af;fragment packets
84 * | for one original packet
88 /* Reassembly headers are stored in hash buckets. */
89 #define IP6REASS_NHASH_LOG2 10
90 #define IP6REASS_NHASH (1 << IP6REASS_NHASH_LOG2)
91 #define IP6REASS_HMASK (IP6REASS_NHASH - 1)
93 TAILQ_HEAD(ip6qhead, ip6q);
95 struct ip6qhead packets;
101 TAILQ_ENTRY(ip6asfrag) ip6af_tq;
102 struct mbuf *ip6af_m;
103 int ip6af_offset; /* Offset in ip6af_m to next header. */
104 int ip6af_frglen; /* Fragmentable part length. */
105 int ip6af_off; /* Fragment offset. */
106 bool ip6af_mff; /* More fragment bit in frag off. */
109 static MALLOC_DEFINE(M_FRAG6, "frag6", "IPv6 fragment reassembly header");
112 /* A flag to indicate if IPv6 fragmentation is initialized. */
113 VNET_DEFINE_STATIC(bool, frag6_on);
114 #define V_frag6_on VNET(frag6_on)
117 /* System wide (global) maximum and count of packets in reassembly queues. */
118 static int ip6_maxfrags;
119 static volatile u_int frag6_nfrags = 0;
121 /* Maximum and current packets in per-VNET reassembly queue. */
122 VNET_DEFINE_STATIC(int, ip6_maxfragpackets);
123 VNET_DEFINE_STATIC(volatile u_int, frag6_nfragpackets);
124 #define V_ip6_maxfragpackets VNET(ip6_maxfragpackets)
125 #define V_frag6_nfragpackets VNET(frag6_nfragpackets)
127 /* Maximum per-VNET reassembly queues per bucket and fragments per packet. */
128 VNET_DEFINE_STATIC(int, ip6_maxfragbucketsize);
129 VNET_DEFINE_STATIC(int, ip6_maxfragsperpacket);
130 #define V_ip6_maxfragbucketsize VNET(ip6_maxfragbucketsize)
131 #define V_ip6_maxfragsperpacket VNET(ip6_maxfragsperpacket)
133 /* Per-VNET reassembly queue buckets. */
134 VNET_DEFINE_STATIC(struct ip6qbucket, ip6qb[IP6REASS_NHASH]);
135 VNET_DEFINE_STATIC(uint32_t, ip6qb_hashseed);
136 #define V_ip6qb VNET(ip6qb)
137 #define V_ip6qb_hashseed VNET(ip6qb_hashseed)
139 #define IP6QB_LOCK(_b) mtx_lock(&V_ip6qb[(_b)].lock)
140 #define IP6QB_TRYLOCK(_b) mtx_trylock(&V_ip6qb[(_b)].lock)
141 #define IP6QB_LOCK_ASSERT(_b) mtx_assert(&V_ip6qb[(_b)].lock, MA_OWNED)
142 #define IP6QB_UNLOCK(_b) mtx_unlock(&V_ip6qb[(_b)].lock)
143 #define IP6QB_HEAD(_b) (&V_ip6qb[(_b)].packets)
146 * By default, limit the number of IP6 fragments across all reassembly
147 * queues to 1/32 of the total number of mbuf clusters.
149 * Limit the total number of reassembly queues per VNET to the
150 * IP6 fragment limit, but ensure the limit will not allow any bucket
151 * to grow above 100 items. (The bucket limit is
152 * IP_MAXFRAGPACKETS / (IPREASS_NHASH / 2), so the 50 is the correct
153 * multiplier to reach a 100-item limit.)
154 * The 100-item limit was chosen as brief testing seems to show that
155 * this produces "reasonable" performance on some subset of systems
158 #define IP6_MAXFRAGS (nmbclusters / 32)
159 #define IP6_MAXFRAGPACKETS (imin(IP6_MAXFRAGS, IP6REASS_NHASH * 50))
162 * Sysctls and helper function.
164 SYSCTL_DECL(_net_inet6_ip6);
166 SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, frag6_nfrags,
167 CTLFLAG_RD, __DEVOLATILE(u_int *, &frag6_nfrags), 0,
168 "Global number of IPv6 fragments across all reassembly queues.");
171 frag6_set_bucketsize(void)
175 if ((i = V_ip6_maxfragpackets) > 0)
176 V_ip6_maxfragbucketsize = imax(i / (IP6REASS_NHASH / 2), 1);
179 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGS, maxfrags,
180 CTLFLAG_RW, &ip6_maxfrags, 0,
181 "Maximum allowed number of outstanding IPv6 packet fragments. "
182 "A value of 0 means no fragmented packets will be accepted, while a "
183 "a value of -1 means no limit");
186 sysctl_ip6_maxfragpackets(SYSCTL_HANDLER_ARGS)
190 val = V_ip6_maxfragpackets;
191 error = sysctl_handle_int(oidp, &val, 0, req);
192 if (error != 0 || !req->newptr)
194 V_ip6_maxfragpackets = val;
195 frag6_set_bucketsize();
198 SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_MAXFRAGPACKETS, maxfragpackets,
199 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
200 NULL, 0, sysctl_ip6_maxfragpackets, "I",
201 "Default maximum number of outstanding fragmented IPv6 packets. "
202 "A value of 0 means no fragmented packets will be accepted, while a "
203 "a value of -1 means no limit");
204 SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, frag6_nfragpackets,
205 CTLFLAG_VNET | CTLFLAG_RD,
206 __DEVOLATILE(u_int *, &VNET_NAME(frag6_nfragpackets)), 0,
207 "Per-VNET number of IPv6 fragments across all reassembly queues.");
208 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGSPERPACKET, maxfragsperpacket,
209 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragsperpacket), 0,
210 "Maximum allowed number of fragments per packet");
211 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGBUCKETSIZE, maxfragbucketsize,
212 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragbucketsize), 0,
213 "Maximum number of reassembly queues per hash bucket");
216 * Remove the IPv6 fragmentation header from the mbuf.
219 ip6_deletefraghdr(struct mbuf *m, int offset, int wait __unused)
223 KASSERT(m->m_len >= offset + sizeof(struct ip6_frag),
224 ("%s: ext headers not contigous in mbuf %p m_len %d >= "
225 "offset %d + %zu\n", __func__, m, m->m_len, offset,
226 sizeof(struct ip6_frag)));
228 /* Delete frag6 header. */
229 ip6 = mtod(m, struct ip6_hdr *);
230 bcopy(ip6, (char *)ip6 + sizeof(struct ip6_frag), offset);
231 m->m_data += sizeof(struct ip6_frag);
232 m->m_len -= sizeof(struct ip6_frag);
233 m->m_flags |= M_FRAGMENTED;
239 * Free a fragment reassembly header and all associated datagrams.
242 frag6_freef(struct ip6q *q6, uint32_t bucket)
245 struct ip6asfrag *af6;
248 IP6QB_LOCK_ASSERT(bucket);
250 while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) {
252 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq);
255 * Return ICMP time exceeded error for the 1st fragment.
256 * Just free other fragments.
258 if (af6->ip6af_off == 0 && m->m_pkthdr.rcvif != NULL) {
259 /* Adjust pointer. */
260 ip6 = mtod(m, struct ip6_hdr *);
262 /* Restore source and destination addresses. */
263 ip6->ip6_src = q6->ip6q_src;
264 ip6->ip6_dst = q6->ip6q_dst;
266 icmp6_error(m, ICMP6_TIME_EXCEEDED,
267 ICMP6_TIME_EXCEED_REASSEMBLY, 0);
274 TAILQ_REMOVE(IP6QB_HEAD(bucket), q6, ip6q_tq);
275 V_ip6qb[bucket].count--;
276 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag);
278 mac_ip6q_destroy(q6);
281 atomic_subtract_int(&V_frag6_nfragpackets, 1);
285 * Drain off all datagram fragments belonging to
286 * the given network interface.
289 frag6_cleanup(void *arg __unused, struct ifnet *ifp)
291 struct ip6qhead *head;
293 struct ip6asfrag *af6;
296 KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__));
298 CURVNET_SET_QUIET(ifp->if_vnet);
301 * Skip processing if IPv6 reassembly is not initialised or
302 * torn down by frag6_destroy().
310 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
312 head = IP6QB_HEAD(bucket);
313 /* Scan fragment list. */
314 TAILQ_FOREACH(q6, head, ip6q_tq) {
315 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) {
316 /* Clear no longer valid rcvif pointer. */
317 if (af6->ip6af_m->m_pkthdr.rcvif == ifp)
318 af6->ip6af_m->m_pkthdr.rcvif = NULL;
321 IP6QB_UNLOCK(bucket);
325 EVENTHANDLER_DEFINE(ifnet_departure_event, frag6_cleanup, NULL, 0);
328 * Like in RFC2460, in RFC8200, fragment and reassembly rules do not agree with
329 * each other, in terms of next header field handling in fragment header.
330 * While the sender will use the same value for all of the fragmented packets,
331 * receiver is suggested not to check for consistency.
333 * Fragment rules (p18,p19):
334 * (2) A Fragment header containing:
335 * The Next Header value that identifies the first header
336 * after the Per-Fragment headers of the original packet.
337 * -> next header field is same for all fragments
339 * Reassembly rule (p20):
340 * The Next Header field of the last header of the Per-Fragment
341 * headers is obtained from the Next Header field of the first
342 * fragment's Fragment header.
343 * -> should grab it from the first fragment only
345 * The following note also contradicts with fragment rule - no one is going to
346 * send different fragment with different next header field.
348 * Additional note (p22) [not an error]:
349 * The Next Header values in the Fragment headers of different
350 * fragments of the same original packet may differ. Only the value
351 * from the Offset zero fragment packet is used for reassembly.
352 * -> should grab it from the first fragment only
354 * There is no explicit reason given in the RFC. Historical reason maybe?
360 frag6_input(struct mbuf **mp, int *offp, int proto)
364 struct ip6_frag *ip6f;
365 struct ip6qhead *head;
367 struct ip6asfrag *af6, *ip6af, *af6tmp;
368 struct in6_ifaddr *ia6;
369 struct ifnet *dstifp, *srcifp;
370 uint32_t hashkey[(sizeof(struct in6_addr) * 2 +
371 sizeof(ip6f->ip6f_ident)) / sizeof(uint32_t)];
372 uint32_t bucket, *hashkeyp;
373 int fragoff, frgpartlen; /* Must be larger than uint16_t. */
374 int nxt, offset, plen;
378 struct ip6_direct_ctx *ip6dc;
387 if (m->m_len < offset + sizeof(struct ip6_frag)) {
388 m = m_pullup(m, offset + sizeof(struct ip6_frag));
390 IP6STAT_INC(ip6s_exthdrtoolong);
392 return (IPPROTO_DONE);
395 ip6 = mtod(m, struct ip6_hdr *);
398 /* Find the destination interface of the packet. */
399 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */);
401 dstifp = ia6->ia_ifp;
402 ifa_free(&ia6->ia_ifa);
405 /* Jumbo payload cannot contain a fragment header. */
406 if (ip6->ip6_plen == 0) {
407 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
408 in6_ifstat_inc(dstifp, ifs6_reass_fail);
410 return (IPPROTO_DONE);
414 * Check whether fragment packet's fragment length is a
415 * multiple of 8 octets (unless it is the last one).
416 * sizeof(struct ip6_frag) == 8
417 * sizeof(struct ip6_hdr) = 40
419 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
420 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
421 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
422 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
423 offsetof(struct ip6_hdr, ip6_plen));
424 in6_ifstat_inc(dstifp, ifs6_reass_fail);
426 return (IPPROTO_DONE);
429 IP6STAT_INC(ip6s_fragments);
430 in6_ifstat_inc(dstifp, ifs6_reass_reqd);
433 * Handle "atomic" fragments (offset and m bit set to 0) upfront,
434 * unrelated to any reassembly. We need to remove the frag hdr
436 * See RFC 6946 and section 4.5 of RFC 8200.
438 if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) {
439 IP6STAT_INC(ip6s_atomicfrags);
440 nxt = ip6f->ip6f_nxt;
442 * Set nxt(-hdr field value) to the original value.
443 * We cannot just set ip6->ip6_nxt as there might be
444 * an unfragmentable part with extension headers and
445 * we must update the last one.
447 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t),
449 ip6->ip6_plen = htons(ntohs(ip6->ip6_plen) -
450 sizeof(struct ip6_frag));
451 if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0)
453 m->m_pkthdr.len -= sizeof(struct ip6_frag);
454 in6_ifstat_inc(dstifp, ifs6_reass_ok);
459 /* Offset now points to data portion. */
460 offset += sizeof(struct ip6_frag);
462 /* Get fragment length and discard 0-byte fragments. */
463 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
464 if (frgpartlen == 0) {
465 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
466 offsetof(struct ip6_hdr, ip6_plen));
467 in6_ifstat_inc(dstifp, ifs6_reass_fail);
468 IP6STAT_INC(ip6s_fragdropped);
470 return (IPPROTO_DONE);
474 * Enforce upper bound on number of fragments for the entire system.
475 * If maxfrag is 0, never accept fragments.
476 * If maxfrag is -1, accept all fragments without limitation.
478 if (ip6_maxfrags < 0)
480 else if (atomic_load_int(&frag6_nfrags) >= (u_int)ip6_maxfrags)
484 * Validate that a full header chain to the ULP is present in the
485 * packet containing the first fragment as per RFC RFC7112 and
486 * RFC 8200 pages 18,19:
487 * The first fragment packet is composed of:
488 * (3) Extension headers, if any, and the Upper-Layer header. These
489 * headers must be in the first fragment. ...
491 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
492 /* XXX TODO. thj has D16851 open for this. */
493 /* Send ICMPv6 4,3 in case of violation. */
495 /* Store receive network interface pointer for later. */
496 srcifp = m->m_pkthdr.rcvif;
498 /* Generate a hash value for fragment bucket selection. */
500 memcpy(hashkeyp, &ip6->ip6_src, sizeof(struct in6_addr));
501 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp);
502 memcpy(hashkeyp, &ip6->ip6_dst, sizeof(struct in6_addr));
503 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp);
504 *hashkeyp = ip6f->ip6f_ident;
505 bucket = jenkins_hash32(hashkey, nitems(hashkey), V_ip6qb_hashseed);
506 bucket &= IP6REASS_HMASK;
508 head = IP6QB_HEAD(bucket);
510 TAILQ_FOREACH(q6, head, ip6q_tq)
511 if (ip6f->ip6f_ident == q6->ip6q_ident &&
512 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
513 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst)
515 && mac_ip6q_match(m, q6)
522 /* A first fragment to arrive creates a reassembly queue. */
526 * Enforce upper bound on number of fragmented packets
527 * for which we attempt reassembly;
528 * If maxfragpackets is 0, never accept fragments.
529 * If maxfragpackets is -1, accept all fragments without
532 if (V_ip6_maxfragpackets < 0)
534 else if (V_ip6qb[bucket].count >= V_ip6_maxfragbucketsize ||
535 atomic_load_int(&V_frag6_nfragpackets) >=
536 (u_int)V_ip6_maxfragpackets)
539 /* Allocate IPv6 fragement packet queue entry. */
540 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FRAG6,
545 if (mac_ip6q_init(q6, M_NOWAIT) != 0) {
549 mac_ip6q_create(m, q6);
551 atomic_add_int(&V_frag6_nfragpackets, 1);
553 /* ip6q_nxt will be filled afterwards, from 1st fragment. */
554 TAILQ_INIT(&q6->ip6q_frags);
555 q6->ip6q_ident = ip6f->ip6f_ident;
556 q6->ip6q_ttl = IPV6_FRAGTTL;
557 q6->ip6q_src = ip6->ip6_src;
558 q6->ip6q_dst = ip6->ip6_dst;
560 (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
561 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
563 /* Add the fragemented packet to the bucket. */
564 TAILQ_INSERT_HEAD(head, q6, ip6q_tq);
565 V_ip6qb[bucket].count++;
569 * If it is the 1st fragment, record the length of the
570 * unfragmentable part and the next header of the fragment header.
571 * Assume the first 1st fragement to arrive will be correct.
572 * We do not have any duplicate checks here yet so another packet
573 * with fragoff == 0 could come and overwrite the ip6q_unfrglen
574 * and worse, the next header, at any time.
576 if (fragoff == 0 && q6->ip6q_unfrglen == -1) {
577 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) -
578 sizeof(struct ip6_frag);
579 q6->ip6q_nxt = ip6f->ip6f_nxt;
584 * Check that the reassembled packet would not exceed 65535 bytes
586 * If it would exceed, discard the fragment and return an ICMP error.
588 if (q6->ip6q_unfrglen >= 0) {
589 /* The 1st fragment has already arrived. */
590 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
592 TAILQ_REMOVE(head, q6, ip6q_tq);
593 V_ip6qb[bucket].count--;
594 atomic_subtract_int(&V_frag6_nfragpackets, 1);
596 mac_ip6q_destroy(q6);
600 IP6QB_UNLOCK(bucket);
601 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
602 offset - sizeof(struct ip6_frag) +
603 offsetof(struct ip6_frag, ip6f_offlg));
605 return (IPPROTO_DONE);
607 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
609 TAILQ_REMOVE(head, q6, ip6q_tq);
610 V_ip6qb[bucket].count--;
611 atomic_subtract_int(&V_frag6_nfragpackets, 1);
613 mac_ip6q_destroy(q6);
617 IP6QB_UNLOCK(bucket);
618 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
619 offset - sizeof(struct ip6_frag) +
620 offsetof(struct ip6_frag, ip6f_offlg));
622 return (IPPROTO_DONE);
626 * If it is the first fragment, do the above check for each
627 * fragment already stored in the reassembly queue.
629 if (fragoff == 0 && !only_frag) {
630 TAILQ_FOREACH_SAFE(af6, &q6->ip6q_frags, ip6af_tq, af6tmp) {
631 if (q6->ip6q_unfrglen + af6->ip6af_off +
632 af6->ip6af_frglen > IPV6_MAXPACKET) {
633 struct ip6_hdr *ip6err;
638 erroff = af6->ip6af_offset;
640 /* Dequeue the fragment. */
641 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq);
643 atomic_subtract_int(&frag6_nfrags, 1);
646 /* Set a valid receive interface pointer. */
647 merr->m_pkthdr.rcvif = srcifp;
649 /* Adjust pointer. */
650 ip6err = mtod(merr, struct ip6_hdr *);
653 * Restore source and destination addresses
654 * in the erroneous IPv6 header.
656 ip6err->ip6_src = q6->ip6q_src;
657 ip6err->ip6_dst = q6->ip6q_dst;
659 icmp6_error(merr, ICMP6_PARAM_PROB,
660 ICMP6_PARAMPROB_HEADER,
661 erroff - sizeof(struct ip6_frag) +
662 offsetof(struct ip6_frag, ip6f_offlg));
667 /* Allocate an IPv6 fragement queue entry for this fragmented part. */
668 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FRAG6,
672 ip6af->ip6af_mff = (ip6f->ip6f_offlg & IP6F_MORE_FRAG) ? true : false;
673 ip6af->ip6af_off = fragoff;
674 ip6af->ip6af_frglen = frgpartlen;
675 ip6af->ip6af_offset = offset;
680 * Do a manual insert rather than a hard-to-understand cast
681 * to a different type relying on data structure order to work.
683 TAILQ_INSERT_HEAD(&q6->ip6q_frags, ip6af, ip6af_tq);
687 /* Do duplicate, condition, and boundry checks. */
689 * Handle ECN by comparing this segment with the first one;
690 * if CE is set, do not lose CE.
691 * Drop if CE and not-ECT are mixed for the same packet.
693 ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
695 if (ecn == IPTOS_ECN_CE) {
696 if (ecn0 == IPTOS_ECN_NOTECT) {
697 free(ip6af, M_FRAG6);
700 if (ecn0 != IPTOS_ECN_CE)
701 q6->ip6q_ecn = IPTOS_ECN_CE;
703 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) {
704 free(ip6af, M_FRAG6);
708 /* Find a fragmented part which begins after this one does. */
709 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq)
710 if (af6->ip6af_off > ip6af->ip6af_off)
714 * If the incoming framgent overlaps some existing fragments in
715 * the reassembly queue, drop both the new fragment and the
716 * entire reassembly queue. However, if the new fragment
717 * is an exact duplicate of an existing fragment, only silently
718 * drop the existing fragment and leave the fragmentation queue
719 * unchanged, as allowed by the RFC. (RFC 8200, 4.5)
722 af6tmp = TAILQ_PREV(af6, ip6fraghead, ip6af_tq);
724 af6tmp = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead);
725 if (af6tmp != NULL) {
726 if (af6tmp->ip6af_off + af6tmp->ip6af_frglen -
727 ip6af->ip6af_off > 0) {
728 if (af6tmp->ip6af_off != ip6af->ip6af_off ||
729 af6tmp->ip6af_frglen != ip6af->ip6af_frglen)
730 frag6_freef(q6, bucket);
731 free(ip6af, M_FRAG6);
736 if (ip6af->ip6af_off + ip6af->ip6af_frglen -
737 af6->ip6af_off > 0) {
738 if (af6->ip6af_off != ip6af->ip6af_off ||
739 af6->ip6af_frglen != ip6af->ip6af_frglen)
740 frag6_freef(q6, bucket);
741 free(ip6af, M_FRAG6);
747 mac_ip6q_update(m, q6);
751 * Stick new segment in its place; check for complete reassembly.
752 * If not complete, check fragment limit. Move to front of packet
753 * queue, as we are the most recently active fragmented packet.
756 TAILQ_INSERT_BEFORE(af6, ip6af, ip6af_tq);
758 TAILQ_INSERT_TAIL(&q6->ip6q_frags, ip6af, ip6af_tq);
760 atomic_add_int(&frag6_nfrags, 1);
764 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) {
765 if (af6->ip6af_off != plen) {
766 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) {
767 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag);
768 frag6_freef(q6, bucket);
770 IP6QB_UNLOCK(bucket);
772 return (IPPROTO_DONE);
774 plen += af6->ip6af_frglen;
776 af6 = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead);
777 if (af6->ip6af_mff) {
778 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) {
779 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag);
780 frag6_freef(q6, bucket);
782 IP6QB_UNLOCK(bucket);
784 return (IPPROTO_DONE);
787 /* Reassembly is complete; concatenate fragments. */
788 ip6af = TAILQ_FIRST(&q6->ip6q_frags);
789 t = m = ip6af->ip6af_m;
790 TAILQ_REMOVE(&q6->ip6q_frags, ip6af, ip6af_tq);
791 while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) {
792 m->m_pkthdr.csum_flags &=
793 af6->ip6af_m->m_pkthdr.csum_flags;
794 m->m_pkthdr.csum_data +=
795 af6->ip6af_m->m_pkthdr.csum_data;
797 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq);
799 m_adj(af6->ip6af_m, af6->ip6af_offset);
800 m_demote_pkthdr(af6->ip6af_m);
801 m_cat(t, af6->ip6af_m);
805 while (m->m_pkthdr.csum_data & 0xffff0000)
806 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) +
807 (m->m_pkthdr.csum_data >> 16);
809 /* Adjust offset to point where the original next header starts. */
810 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
811 free(ip6af, M_FRAG6);
812 ip6 = mtod(m, struct ip6_hdr *);
813 ip6->ip6_plen = htons((u_short)plen + offset - sizeof(struct ip6_hdr));
814 if (q6->ip6q_ecn == IPTOS_ECN_CE)
815 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20);
818 TAILQ_REMOVE(head, q6, ip6q_tq);
819 V_ip6qb[bucket].count--;
820 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag);
822 ip6_deletefraghdr(m, offset, M_NOWAIT);
824 /* Set nxt(-hdr field value) to the original value. */
825 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t),
829 mac_ip6q_reassemble(q6, m);
830 mac_ip6q_destroy(q6);
833 atomic_subtract_int(&V_frag6_nfragpackets, 1);
835 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
838 for (t = m; t; t = t->m_next)
840 m->m_pkthdr.len = plen;
841 /* Set a valid receive interface pointer. */
842 m->m_pkthdr.rcvif = srcifp;
846 mtag = m_tag_alloc(MTAG_ABI_IPV6, IPV6_TAG_DIRECT, sizeof(*ip6dc),
851 ip6dc = (struct ip6_direct_ctx *)(mtag + 1);
852 ip6dc->ip6dc_nxt = nxt;
853 ip6dc->ip6dc_off = offset;
855 m_tag_prepend(m, mtag);
858 IP6QB_UNLOCK(bucket);
859 IP6STAT_INC(ip6s_reassembled);
860 in6_ifstat_inc(dstifp, ifs6_reass_ok);
863 /* Queue/dispatch for reprocessing. */
864 netisr_dispatch(NETISR_IPV6_DIRECT, m);
866 return (IPPROTO_DONE);
869 /* Tell launch routine the next header. */
876 IP6QB_UNLOCK(bucket);
878 in6_ifstat_inc(dstifp, ifs6_reass_fail);
879 IP6STAT_INC(ip6s_fragdropped);
882 return (IPPROTO_DONE);
886 * IPv6 reassembling timer processing;
887 * if a timer expires on a reassembly queue, discard it.
892 VNET_ITERATOR_DECL(vnet_iter);
893 struct ip6qhead *head;
894 struct ip6q *q6, *q6tmp;
897 VNET_LIST_RLOCK_NOSLEEP();
898 VNET_FOREACH(vnet_iter) {
899 CURVNET_SET(vnet_iter);
900 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
902 head = IP6QB_HEAD(bucket);
903 TAILQ_FOREACH_SAFE(q6, head, ip6q_tq, q6tmp)
904 if (--q6->ip6q_ttl == 0) {
905 IP6STAT_ADD(ip6s_fragtimeout,
907 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
908 frag6_freef(q6, bucket);
911 * If we are over the maximum number of fragments
912 * (due to the limit being lowered), drain off
913 * enough to get down to the new limit.
914 * Note that we drain all reassembly queues if
915 * maxfragpackets is 0 (fragmentation is disabled),
916 * and do not enforce a limit when maxfragpackets
919 while ((V_ip6_maxfragpackets == 0 ||
920 (V_ip6_maxfragpackets > 0 &&
921 V_ip6qb[bucket].count > V_ip6_maxfragbucketsize)) &&
922 (q6 = TAILQ_LAST(head, ip6qhead)) != NULL) {
923 IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag);
924 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
925 frag6_freef(q6, bucket);
927 IP6QB_UNLOCK(bucket);
930 * If we are still over the maximum number of fragmented
931 * packets, drain off enough to get down to the new limit.
934 while (V_ip6_maxfragpackets >= 0 &&
935 atomic_load_int(&V_frag6_nfragpackets) >
936 (u_int)V_ip6_maxfragpackets) {
938 q6 = TAILQ_LAST(IP6QB_HEAD(bucket), ip6qhead);
940 IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag);
941 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
942 frag6_freef(q6, bucket);
944 IP6QB_UNLOCK(bucket);
945 bucket = (bucket + 1) % IP6REASS_NHASH;
949 VNET_LIST_RUNLOCK_NOSLEEP();
953 * Eventhandler to adjust limits in case nmbclusters change.
956 frag6_change(void *tag)
958 VNET_ITERATOR_DECL(vnet_iter);
960 ip6_maxfrags = IP6_MAXFRAGS;
961 VNET_LIST_RLOCK_NOSLEEP();
962 VNET_FOREACH(vnet_iter) {
963 CURVNET_SET(vnet_iter);
964 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS;
965 frag6_set_bucketsize();
968 VNET_LIST_RUNLOCK_NOSLEEP();
972 * Initialise reassembly queue and fragment identifier.
979 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS;
980 frag6_set_bucketsize();
981 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
982 TAILQ_INIT(IP6QB_HEAD(bucket));
983 mtx_init(&V_ip6qb[bucket].lock, "ip6qb", NULL, MTX_DEF);
984 V_ip6qb[bucket].count = 0;
986 V_ip6qb_hashseed = arc4random();
987 V_ip6_maxfragsperpacket = 64;
991 if (!IS_DEFAULT_VNET(curvnet))
994 ip6_maxfrags = IP6_MAXFRAGS;
995 EVENTHANDLER_REGISTER(nmbclusters_change,
996 frag6_change, NULL, EVENTHANDLER_PRI_ANY);
1000 * Drain off all datagram fragments.
1003 frag6_drain_one(void)
1008 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
1010 while ((q6 = TAILQ_FIRST(IP6QB_HEAD(bucket))) != NULL) {
1011 IP6STAT_INC(ip6s_fragdropped);
1012 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
1013 frag6_freef(q6, bucket);
1015 IP6QB_UNLOCK(bucket);
1022 VNET_ITERATOR_DECL(vnet_iter);
1024 VNET_LIST_RLOCK_NOSLEEP();
1025 VNET_FOREACH(vnet_iter) {
1026 CURVNET_SET(vnet_iter);
1030 VNET_LIST_RUNLOCK_NOSLEEP();
1035 * Clear up IPv6 reassembly structures.
1044 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
1045 KASSERT(V_ip6qb[bucket].count == 0,
1046 ("%s: V_ip6qb[%d] (%p) count not 0 (%d)", __func__,
1047 bucket, &V_ip6qb[bucket], V_ip6qb[bucket].count));
1048 mtx_destroy(&V_ip6qb[bucket].lock);