5 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
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 * 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
33#include <sys/param.h>
34#include <sys/systm.h>
35#include <sys/malloc.h>
36#include <sys/mbuf.h>
37#include <sys/domain.h>
38#include <sys/protosw.h>
39#include <sys/socket.h>
40#include <sys/errno.h>
41#include <sys/time.h>
42#include <sys/kernel.h>
43#include <sys/syslog.h>
44
45#include <net/if.h>
46#include <net/route.h>
47
48#include <netinet/in.h>
49#include <netinet/in_var.h>
50#include <netinet/ip6.h>
51#include <netinet6/ip6_var.h>
52#include <netinet/icmp6.h>
53#include <netinet/in_systm.h> /* for ECN definitions */
54#include <netinet/ip.h> /* for ECN definitions */
55
56#include <net/net_osdep.h>
57
58/*
59 * Define it to get a correct behavior on per-interface statistics.
60 * You will need to perform an extra routing table lookup, per fragment,
61 * to do it. This may, or may not be, a performance hit.
62 */
63#define IN6_IFSTAT_STRICT
64
65static void frag6_enq __P((struct ip6asfrag *, struct ip6asfrag *));
66static void frag6_deq __P((struct ip6asfrag *));
67static void frag6_insque __P((struct ip6q *, struct ip6q *));
68static void frag6_remque __P((struct ip6q *));
69static void frag6_freef __P((struct ip6q *));
70
71static struct mtx ip6qlock;
72/*
73 * These fields all protected by ip6qlock.
74 */
75static u_int frag6_nfragpackets;
76static u_int frag6_nfrags;
77static struct ip6q ip6q; /* ip6 reassemble queue */
78
79#define IP6Q_LOCK_INIT() mtx_init(&ip6qlock, "ip6qlock", NULL, MTX_DEF);
80#define IP6Q_LOCK() mtx_lock(&ip6qlock)
81#define IP6Q_TRYLOCK() mtx_trylock(&ip6qlock)
82#define IP6Q_LOCK_ASSERT() mtx_assert(&ip6qlock, MA_OWNED)
83#define IP6Q_UNLOCK() mtx_unlock(&ip6qlock)
84
85static MALLOC_DEFINE(M_FTABLE, "fragment", "fragment reassembly header");
86
87/*
88 * Initialise reassembly queue and fragment identifier.
89 */
90void
91frag6_init()
92{
93
94 ip6_maxfragpackets = nmbclusters / 4;
95 ip6_maxfrags = nmbclusters / 4;
96
97 IP6Q_LOCK_INIT();
98
99 ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q;
100}
101
102/*
103 * In RFC2460, fragment and reassembly rule do not agree with each other,
104 * in terms of next header field handling in fragment header.
105 * While the sender will use the same value for all of the fragmented packets,
106 * receiver is suggested not to check the consistency.
107 *
108 * fragment rule (p20):
109 * (2) A Fragment header containing:
110 * The Next Header value that identifies the first header of
111 * the Fragmentable Part of the original packet.
112 * -> next header field is same for all fragments
113 *
114 * reassembly rule (p21):
115 * The Next Header field of the last header of the Unfragmentable
116 * Part is obtained from the Next Header field of the first
117 * fragment's Fragment header.
118 * -> should grab it from the first fragment only
119 *
120 * The following note also contradicts with fragment rule - noone is going to
121 * send different fragment with different next header field.
122 *
123 * additional note (p22):
124 * The Next Header values in the Fragment headers of different
125 * fragments of the same original packet may differ. Only the value
126 * from the Offset zero fragment packet is used for reassembly.
127 * -> should grab it from the first fragment only
128 *
129 * There is no explicit reason given in the RFC. Historical reason maybe?
130 */
131/*
132 * Fragment input
133 */
134int
135frag6_input(mp, offp, proto)
136 struct mbuf **mp;
137 int *offp, proto;
138{
139 struct mbuf *m = *mp, *t;
140 struct ip6_hdr *ip6;
141 struct ip6_frag *ip6f;
142 struct ip6q *q6;
143 struct ip6asfrag *af6, *ip6af, *af6dwn;
144#ifdef IN6_IFSTAT_STRICT
145 struct in6_ifaddr *ia;
146#endif
147 int offset = *offp, nxt, i, next;
148 int first_frag = 0;
149 int fragoff, frgpartlen; /* must be larger than u_int16_t */
150 struct ifnet *dstifp;
151 u_int8_t ecn, ecn0;
152
153 ip6 = mtod(m, struct ip6_hdr *);
154#ifndef PULLDOWN_TEST
155 IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE);
156 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
157#else
158 IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
159 if (ip6f == NULL)
160 return (IPPROTO_DONE);
161#endif
162
163 dstifp = NULL;
164#ifdef IN6_IFSTAT_STRICT
165 /* find the destination interface of the packet. */
166 if ((ia = ip6_getdstifaddr(m)) != NULL)
167 dstifp = ia->ia_ifp;
168#else
169 /* we are violating the spec, this is not the destination interface */
170 if ((m->m_flags & M_PKTHDR) != 0)
171 dstifp = m->m_pkthdr.rcvif;
172#endif
173
174 /* jumbo payload can't contain a fragment header */
175 if (ip6->ip6_plen == 0) {
176 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
177 in6_ifstat_inc(dstifp, ifs6_reass_fail);
178 return IPPROTO_DONE;
179 }
180
181 /*
182 * check whether fragment packet's fragment length is
183 * multiple of 8 octets.
184 * sizeof(struct ip6_frag) == 8
185 * sizeof(struct ip6_hdr) = 40
186 */
187 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
188 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
189 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
190 offsetof(struct ip6_hdr, ip6_plen));
191 in6_ifstat_inc(dstifp, ifs6_reass_fail);
192 return IPPROTO_DONE;
193 }
194
195 ip6stat.ip6s_fragments++;
196 in6_ifstat_inc(dstifp, ifs6_reass_reqd);
197
198 /* offset now points to data portion */
199 offset += sizeof(struct ip6_frag);
200
201 IP6Q_LOCK();
202
203 /*
204 * Enforce upper bound on number of fragments.
205 * If maxfrag is 0, never accept fragments.
206 * If maxfrag is -1, accept all fragments without limitation.
207 */
208 if (ip6_maxfrags < 0)
209 ;
210 else if (frag6_nfrags >= (u_int)ip6_maxfrags)
211 goto dropfrag;
212
213 for (q6 = ip6q.ip6q_next; q6 != &ip6q; q6 = q6->ip6q_next)
214 if (ip6f->ip6f_ident == q6->ip6q_ident &&
215 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
216 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst))
217 break;
218
219 if (q6 == &ip6q) {
220 /*
221 * the first fragment to arrive, create a reassembly queue.
222 */
223 first_frag = 1;
224
225 /*
226 * Enforce upper bound on number of fragmented packets
227 * for which we attempt reassembly;
228 * If maxfragpackets is 0, never accept fragments.
229 * If maxfragpackets is -1, accept all fragments without
230 * limitation.
231 */
232 if (ip6_maxfragpackets < 0)
233 ;
234 else if (frag6_nfragpackets >= (u_int)ip6_maxfragpackets)
235 goto dropfrag;
236 frag6_nfragpackets++;
237 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE,
238 M_NOWAIT);
239 if (q6 == NULL)
240 goto dropfrag;
241 bzero(q6, sizeof(*q6));
242
243 frag6_insque(q6, &ip6q);
244
245 /* ip6q_nxt will be filled afterwards, from 1st fragment */
246 q6->ip6q_down = q6->ip6q_up = (struct ip6asfrag *)q6;
247#ifdef notyet
248 q6->ip6q_nxtp = (u_char *)nxtp;
249#endif
250 q6->ip6q_ident = ip6f->ip6f_ident;
251 q6->ip6q_arrive = 0; /* Is it used anywhere? */
252 q6->ip6q_ttl = IPV6_FRAGTTL;
253 q6->ip6q_src = ip6->ip6_src;
254 q6->ip6q_dst = ip6->ip6_dst;
255 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
256
257 q6->ip6q_nfrag = 0;
258 }
259
260 /*
261 * If it's the 1st fragment, record the length of the
262 * unfragmentable part and the next header of the fragment header.
263 */
264 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
265 if (fragoff == 0) {
266 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) -
267 sizeof(struct ip6_frag);
268 q6->ip6q_nxt = ip6f->ip6f_nxt;
269 }
270
271 /*
272 * Check that the reassembled packet would not exceed 65535 bytes
273 * in size.
274 * If it would exceed, discard the fragment and return an ICMP error.
275 */
276 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
277 if (q6->ip6q_unfrglen >= 0) {
278 /* The 1st fragment has already arrived. */
279 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
280 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
281 offset - sizeof(struct ip6_frag) +
282 offsetof(struct ip6_frag, ip6f_offlg));
283 IP6Q_UNLOCK();
284 return (IPPROTO_DONE);
285 }
286 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
287 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
288 offset - sizeof(struct ip6_frag) +
289 offsetof(struct ip6_frag, ip6f_offlg));
290 IP6Q_UNLOCK();
291 return (IPPROTO_DONE);
292 }
293 /*
294 * If it's the first fragment, do the above check for each
295 * fragment already stored in the reassembly queue.
296 */
297 if (fragoff == 0) {
298 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
299 af6 = af6dwn) {
300 af6dwn = af6->ip6af_down;
301
302 if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen >
303 IPV6_MAXPACKET) {
304 struct mbuf *merr = IP6_REASS_MBUF(af6);
305 struct ip6_hdr *ip6err;
306 int erroff = af6->ip6af_offset;
307
308 /* dequeue the fragment. */
309 frag6_deq(af6);
310 free(af6, M_FTABLE);
311
312 /* adjust pointer. */
313 ip6err = mtod(merr, struct ip6_hdr *);
314
315 /*
316 * Restore source and destination addresses
317 * in the erroneous IPv6 header.
318 */
319 ip6err->ip6_src = q6->ip6q_src;
320 ip6err->ip6_dst = q6->ip6q_dst;
321
322 icmp6_error(merr, ICMP6_PARAM_PROB,
323 ICMP6_PARAMPROB_HEADER,
324 erroff - sizeof(struct ip6_frag) +
325 offsetof(struct ip6_frag, ip6f_offlg));
326 }
327 }
328 }
329
330 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FTABLE,
331 M_NOWAIT);
332 if (ip6af == NULL)
333 goto dropfrag;
334 bzero(ip6af, sizeof(*ip6af));
335 ip6af->ip6af_head = ip6->ip6_flow;
336 ip6af->ip6af_len = ip6->ip6_plen;
337 ip6af->ip6af_nxt = ip6->ip6_nxt;
338 ip6af->ip6af_hlim = ip6->ip6_hlim;
339 ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG;
340 ip6af->ip6af_off = fragoff;
341 ip6af->ip6af_frglen = frgpartlen;
342 ip6af->ip6af_offset = offset;
343 IP6_REASS_MBUF(ip6af) = m;
344
345 if (first_frag) {
346 af6 = (struct ip6asfrag *)q6;
347 goto insert;
348 }
349
350 /*
351 * Handle ECN by comparing this segment with the first one;
352 * if CE is set, do not lose CE.
353 * drop if CE and not-ECT are mixed for the same packet.
354 */
355 ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
356 ecn0 = (ntohl(q6->ip6q_down->ip6af_head) >> 20) & IPTOS_ECN_MASK;
357 if (ecn == IPTOS_ECN_CE) {
358 if (ecn0 == IPTOS_ECN_NOTECT) {
359 free(ip6af, M_FTABLE);
360 goto dropfrag;
361 }
362 if (ecn0 != IPTOS_ECN_CE)
363 q6->ip6q_down->ip6af_head |= htonl(IPTOS_ECN_CE << 20);
364 }
365 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) {
366 free(ip6af, M_FTABLE);
367 goto dropfrag;
368 }
369
370 /*
371 * Find a segment which begins after this one does.
372 */
373 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
374 af6 = af6->ip6af_down)
375 if (af6->ip6af_off > ip6af->ip6af_off)
376 break;
377
378#if 0
379 /*
380 * If there is a preceding segment, it may provide some of
381 * our data already. If so, drop the data from the incoming
382 * segment. If it provides all of our data, drop us.
383 */
384 if (af6->ip6af_up != (struct ip6asfrag *)q6) {
385 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
386 - ip6af->ip6af_off;
387 if (i > 0) {
388 if (i >= ip6af->ip6af_frglen)
389 goto dropfrag;
390 m_adj(IP6_REASS_MBUF(ip6af), i);
391 ip6af->ip6af_off += i;
392 ip6af->ip6af_frglen -= i;
393 }
394 }
395
396 /*
397 * While we overlap succeeding segments trim them or,
398 * if they are completely covered, dequeue them.
399 */
400 while (af6 != (struct ip6asfrag *)q6 &&
401 ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) {
402 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
403 if (i < af6->ip6af_frglen) {
404 af6->ip6af_frglen -= i;
405 af6->ip6af_off += i;
406 m_adj(IP6_REASS_MBUF(af6), i);
407 break;
408 }
409 af6 = af6->ip6af_down;
410 m_freem(IP6_REASS_MBUF(af6->ip6af_up));
411 frag6_deq(af6->ip6af_up);
412 }
413#else
414 /*
415 * If the incoming framgent overlaps some existing fragments in
416 * the reassembly queue, drop it, since it is dangerous to override
417 * existing fragments from a security point of view.
418 * We don't know which fragment is the bad guy - here we trust
419 * fragment that came in earlier, with no real reason.
420 */
421 if (af6->ip6af_up != (struct ip6asfrag *)q6) {
422 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
423 - ip6af->ip6af_off;
424 if (i > 0) {
425#if 0 /* suppress the noisy log */
426 log(LOG_ERR, "%d bytes of a fragment from %s "
427 "overlaps the previous fragment\n",
428 i, ip6_sprintf(&q6->ip6q_src));
429#endif
430 free(ip6af, M_FTABLE);
431 goto dropfrag;
432 }
433 }
434 if (af6 != (struct ip6asfrag *)q6) {
435 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
436 if (i > 0) {
437#if 0 /* suppress the noisy log */
438 log(LOG_ERR, "%d bytes of a fragment from %s "
439 "overlaps the succeeding fragment",
440 i, ip6_sprintf(&q6->ip6q_src));
441#endif
442 free(ip6af, M_FTABLE);
443 goto dropfrag;
444 }
445 }
446#endif
447
448insert:
449
450 /*
451 * Stick new segment in its place;
452 * check for complete reassembly.
453 * Move to front of packet queue, as we are
454 * the most recently active fragmented packet.
455 */
456 frag6_enq(ip6af, af6->ip6af_up);
457 frag6_nfrags++;
458 q6->ip6q_nfrag++;
459#if 0 /* xxx */
460 if (q6 != ip6q.ip6q_next) {
461 frag6_remque(q6);
462 frag6_insque(q6, &ip6q);
463 }
464#endif
465 next = 0;
466 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
467 af6 = af6->ip6af_down) {
468 if (af6->ip6af_off != next) {
469 IP6Q_UNLOCK();
470 return IPPROTO_DONE;
471 }
472 next += af6->ip6af_frglen;
473 }
474 if (af6->ip6af_up->ip6af_mff) {
475 IP6Q_UNLOCK();
476 return IPPROTO_DONE;
477 }
478
479 /*
480 * Reassembly is complete; concatenate fragments.
481 */
482 ip6af = q6->ip6q_down;
483 t = m = IP6_REASS_MBUF(ip6af);
484 af6 = ip6af->ip6af_down;
485 frag6_deq(ip6af);
486 while (af6 != (struct ip6asfrag *)q6) {
487 af6dwn = af6->ip6af_down;
488 frag6_deq(af6);
489 while (t->m_next)
490 t = t->m_next;
491 t->m_next = IP6_REASS_MBUF(af6);
492 m_adj(t->m_next, af6->ip6af_offset);
493 free(af6, M_FTABLE);
494 af6 = af6dwn;
495 }
496
497 /* adjust offset to point where the original next header starts */
498 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
499 free(ip6af, M_FTABLE);
500 ip6 = mtod(m, struct ip6_hdr *);
501 ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr));
502 ip6->ip6_src = q6->ip6q_src;
503 ip6->ip6_dst = q6->ip6q_dst;
504 nxt = q6->ip6q_nxt;
505#ifdef notyet
506 *q6->ip6q_nxtp = (u_char)(nxt & 0xff);
507#endif
508
509 /*
510 * Delete frag6 header with as a few cost as possible.
511 */
512 if (offset < m->m_len) {
513 ovbcopy((caddr_t)ip6, (caddr_t)ip6 + sizeof(struct ip6_frag),
514 offset);
515 m->m_data += sizeof(struct ip6_frag);
516 m->m_len -= sizeof(struct ip6_frag);
517 } else {
518 /* this comes with no copy if the boundary is on cluster */
519 if ((t = m_split(m, offset, M_DONTWAIT)) == NULL) {
520 frag6_remque(q6);
521 frag6_nfrags -= q6->ip6q_nfrag;
522 free(q6, M_FTABLE);
523 frag6_nfragpackets--;
524 goto dropfrag;
525 }
526 m_adj(t, sizeof(struct ip6_frag));
527 m_cat(m, t);
528 }
529
530 /*
531 * Store NXT to the original.
532 */
533 {
534 char *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */
535 *prvnxtp = nxt;
536 }
537
538 frag6_remque(q6);
539 frag6_nfrags -= q6->ip6q_nfrag;
540 free(q6, M_FTABLE);
541 frag6_nfragpackets--;
542
543 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
544 int plen = 0;
545 for (t = m; t; t = t->m_next)
546 plen += t->m_len;
547 m->m_pkthdr.len = plen;
548 }
549
550 ip6stat.ip6s_reassembled++;
551 in6_ifstat_inc(dstifp, ifs6_reass_ok);
552
553 /*
554 * Tell launch routine the next header
555 */
556
557 *mp = m;
558 *offp = offset;
559
560 IP6Q_UNLOCK();
561 return nxt;
562
563 dropfrag:
564 IP6Q_UNLOCK();
565 in6_ifstat_inc(dstifp, ifs6_reass_fail);
566 ip6stat.ip6s_fragdropped++;
567 m_freem(m);
568 return IPPROTO_DONE;
569}
570
571/*
572 * Free a fragment reassembly header and all
573 * associated datagrams.
574 */
575void
576frag6_freef(q6)
577 struct ip6q *q6;
578{
579 struct ip6asfrag *af6, *down6;
580
581 IP6Q_LOCK_ASSERT();
582
583 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
584 af6 = down6) {
585 struct mbuf *m = IP6_REASS_MBUF(af6);
586
587 down6 = af6->ip6af_down;
588 frag6_deq(af6);
589
590 /*
591 * Return ICMP time exceeded error for the 1st fragment.
592 * Just free other fragments.
593 */
594 if (af6->ip6af_off == 0) {
595 struct ip6_hdr *ip6;
596
597 /* adjust pointer */
598 ip6 = mtod(m, struct ip6_hdr *);
599
600 /* restore source and destination addresses */
601 ip6->ip6_src = q6->ip6q_src;
602 ip6->ip6_dst = q6->ip6q_dst;
603
604 icmp6_error(m, ICMP6_TIME_EXCEEDED,
605 ICMP6_TIME_EXCEED_REASSEMBLY, 0);
606 } else
607 m_freem(m);
608 free(af6, M_FTABLE);
609 }
610 frag6_remque(q6);
611 frag6_nfrags -= q6->ip6q_nfrag;
612 free(q6, M_FTABLE);
613 frag6_nfragpackets--;
614}
615
616/*
617 * Put an ip fragment on a reassembly chain.
618 * Like insque, but pointers in middle of structure.
619 */
620void
621frag6_enq(af6, up6)
622 struct ip6asfrag *af6, *up6;
623{
624
625 IP6Q_LOCK_ASSERT();
626
627 af6->ip6af_up = up6;
628 af6->ip6af_down = up6->ip6af_down;
629 up6->ip6af_down->ip6af_up = af6;
630 up6->ip6af_down = af6;
631}
632
633/*
634 * To frag6_enq as remque is to insque.
635 */
636void
637frag6_deq(af6)
638 struct ip6asfrag *af6;
639{
640
641 IP6Q_LOCK_ASSERT();
642
643 af6->ip6af_up->ip6af_down = af6->ip6af_down;
644 af6->ip6af_down->ip6af_up = af6->ip6af_up;
645}
646
647void
648frag6_insque(new, old)
649 struct ip6q *new, *old;
650{
651
652 IP6Q_LOCK_ASSERT();
653
654 new->ip6q_prev = old;
655 new->ip6q_next = old->ip6q_next;
656 old->ip6q_next->ip6q_prev= new;
657 old->ip6q_next = new;
658}
659
660void
661frag6_remque(p6)
662 struct ip6q *p6;
663{
664
665 IP6Q_LOCK_ASSERT();
666
667 p6->ip6q_prev->ip6q_next = p6->ip6q_next;
668 p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
669}
670
671/*
672 * IPv6 reassembling timer processing;
673 * if a timer expires on a reassembly
674 * queue, discard it.
675 */
676void
677frag6_slowtimo()
678{
679 struct ip6q *q6;
680 int s = splnet();
681
682 IP6Q_LOCK();
683 q6 = ip6q.ip6q_next;
684 if (q6)
685 while (q6 != &ip6q) {
686 --q6->ip6q_ttl;
687 q6 = q6->ip6q_next;
688 if (q6->ip6q_prev->ip6q_ttl == 0) {
689 ip6stat.ip6s_fragtimeout++;
690 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
691 frag6_freef(q6->ip6q_prev);
692 }
693 }
694 /*
695 * If we are over the maximum number of fragments
696 * (due to the limit being lowered), drain off
697 * enough to get down to the new limit.
698 */
699 while (frag6_nfragpackets > (u_int)ip6_maxfragpackets &&
700 ip6q.ip6q_prev) {
701 ip6stat.ip6s_fragoverflow++;
702 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
703 frag6_freef(ip6q.ip6q_prev);
704 }
705 IP6Q_UNLOCK();
706
707#if 0
708 /*
709 * Routing changes might produce a better route than we last used;
710 * make sure we notice eventually, even if forwarding only for one
711 * destination and the cache is never replaced.
712 */
713 if (ip6_forward_rt.ro_rt) {
714 RTFREE(ip6_forward_rt.ro_rt);
715 ip6_forward_rt.ro_rt = 0;
716 }
717 if (ipsrcchk_rt.ro_rt) {
718 RTFREE(ipsrcchk_rt.ro_rt);
719 ipsrcchk_rt.ro_rt = 0;
720 }
721#endif
722
723 splx(s);
724}
725
726/*
727 * Drain off all datagram fragments.
728 */
729void
730frag6_drain()
731{
732
733 if (IP6Q_TRYLOCK() == 0)
734 return;
735 while (ip6q.ip6q_next != &ip6q) {
736 ip6stat.ip6s_fragdropped++;
737 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
738 frag6_freef(ip6q.ip6q_next);
739 }
740 IP6Q_UNLOCK();
741}
| 5 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
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 * 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
33#include <sys/param.h>
34#include <sys/systm.h>
35#include <sys/malloc.h>
36#include <sys/mbuf.h>
37#include <sys/domain.h>
38#include <sys/protosw.h>
39#include <sys/socket.h>
40#include <sys/errno.h>
41#include <sys/time.h>
42#include <sys/kernel.h>
43#include <sys/syslog.h>
44
45#include <net/if.h>
46#include <net/route.h>
47
48#include <netinet/in.h>
49#include <netinet/in_var.h>
50#include <netinet/ip6.h>
51#include <netinet6/ip6_var.h>
52#include <netinet/icmp6.h>
53#include <netinet/in_systm.h> /* for ECN definitions */
54#include <netinet/ip.h> /* for ECN definitions */
55
56#include <net/net_osdep.h>
57
58/*
59 * Define it to get a correct behavior on per-interface statistics.
60 * You will need to perform an extra routing table lookup, per fragment,
61 * to do it. This may, or may not be, a performance hit.
62 */
63#define IN6_IFSTAT_STRICT
64
65static void frag6_enq __P((struct ip6asfrag *, struct ip6asfrag *));
66static void frag6_deq __P((struct ip6asfrag *));
67static void frag6_insque __P((struct ip6q *, struct ip6q *));
68static void frag6_remque __P((struct ip6q *));
69static void frag6_freef __P((struct ip6q *));
70
71static struct mtx ip6qlock;
72/*
73 * These fields all protected by ip6qlock.
74 */
75static u_int frag6_nfragpackets;
76static u_int frag6_nfrags;
77static struct ip6q ip6q; /* ip6 reassemble queue */
78
79#define IP6Q_LOCK_INIT() mtx_init(&ip6qlock, "ip6qlock", NULL, MTX_DEF);
80#define IP6Q_LOCK() mtx_lock(&ip6qlock)
81#define IP6Q_TRYLOCK() mtx_trylock(&ip6qlock)
82#define IP6Q_LOCK_ASSERT() mtx_assert(&ip6qlock, MA_OWNED)
83#define IP6Q_UNLOCK() mtx_unlock(&ip6qlock)
84
85static MALLOC_DEFINE(M_FTABLE, "fragment", "fragment reassembly header");
86
87/*
88 * Initialise reassembly queue and fragment identifier.
89 */
90void
91frag6_init()
92{
93
94 ip6_maxfragpackets = nmbclusters / 4;
95 ip6_maxfrags = nmbclusters / 4;
96
97 IP6Q_LOCK_INIT();
98
99 ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q;
100}
101
102/*
103 * In RFC2460, fragment and reassembly rule do not agree with each other,
104 * in terms of next header field handling in fragment header.
105 * While the sender will use the same value for all of the fragmented packets,
106 * receiver is suggested not to check the consistency.
107 *
108 * fragment rule (p20):
109 * (2) A Fragment header containing:
110 * The Next Header value that identifies the first header of
111 * the Fragmentable Part of the original packet.
112 * -> next header field is same for all fragments
113 *
114 * reassembly rule (p21):
115 * The Next Header field of the last header of the Unfragmentable
116 * Part is obtained from the Next Header field of the first
117 * fragment's Fragment header.
118 * -> should grab it from the first fragment only
119 *
120 * The following note also contradicts with fragment rule - noone is going to
121 * send different fragment with different next header field.
122 *
123 * additional note (p22):
124 * The Next Header values in the Fragment headers of different
125 * fragments of the same original packet may differ. Only the value
126 * from the Offset zero fragment packet is used for reassembly.
127 * -> should grab it from the first fragment only
128 *
129 * There is no explicit reason given in the RFC. Historical reason maybe?
130 */
131/*
132 * Fragment input
133 */
134int
135frag6_input(mp, offp, proto)
136 struct mbuf **mp;
137 int *offp, proto;
138{
139 struct mbuf *m = *mp, *t;
140 struct ip6_hdr *ip6;
141 struct ip6_frag *ip6f;
142 struct ip6q *q6;
143 struct ip6asfrag *af6, *ip6af, *af6dwn;
144#ifdef IN6_IFSTAT_STRICT
145 struct in6_ifaddr *ia;
146#endif
147 int offset = *offp, nxt, i, next;
148 int first_frag = 0;
149 int fragoff, frgpartlen; /* must be larger than u_int16_t */
150 struct ifnet *dstifp;
151 u_int8_t ecn, ecn0;
152
153 ip6 = mtod(m, struct ip6_hdr *);
154#ifndef PULLDOWN_TEST
155 IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE);
156 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
157#else
158 IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
159 if (ip6f == NULL)
160 return (IPPROTO_DONE);
161#endif
162
163 dstifp = NULL;
164#ifdef IN6_IFSTAT_STRICT
165 /* find the destination interface of the packet. */
166 if ((ia = ip6_getdstifaddr(m)) != NULL)
167 dstifp = ia->ia_ifp;
168#else
169 /* we are violating the spec, this is not the destination interface */
170 if ((m->m_flags & M_PKTHDR) != 0)
171 dstifp = m->m_pkthdr.rcvif;
172#endif
173
174 /* jumbo payload can't contain a fragment header */
175 if (ip6->ip6_plen == 0) {
176 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
177 in6_ifstat_inc(dstifp, ifs6_reass_fail);
178 return IPPROTO_DONE;
179 }
180
181 /*
182 * check whether fragment packet's fragment length is
183 * multiple of 8 octets.
184 * sizeof(struct ip6_frag) == 8
185 * sizeof(struct ip6_hdr) = 40
186 */
187 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
188 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
189 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
190 offsetof(struct ip6_hdr, ip6_plen));
191 in6_ifstat_inc(dstifp, ifs6_reass_fail);
192 return IPPROTO_DONE;
193 }
194
195 ip6stat.ip6s_fragments++;
196 in6_ifstat_inc(dstifp, ifs6_reass_reqd);
197
198 /* offset now points to data portion */
199 offset += sizeof(struct ip6_frag);
200
201 IP6Q_LOCK();
202
203 /*
204 * Enforce upper bound on number of fragments.
205 * If maxfrag is 0, never accept fragments.
206 * If maxfrag is -1, accept all fragments without limitation.
207 */
208 if (ip6_maxfrags < 0)
209 ;
210 else if (frag6_nfrags >= (u_int)ip6_maxfrags)
211 goto dropfrag;
212
213 for (q6 = ip6q.ip6q_next; q6 != &ip6q; q6 = q6->ip6q_next)
214 if (ip6f->ip6f_ident == q6->ip6q_ident &&
215 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
216 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst))
217 break;
218
219 if (q6 == &ip6q) {
220 /*
221 * the first fragment to arrive, create a reassembly queue.
222 */
223 first_frag = 1;
224
225 /*
226 * Enforce upper bound on number of fragmented packets
227 * for which we attempt reassembly;
228 * If maxfragpackets is 0, never accept fragments.
229 * If maxfragpackets is -1, accept all fragments without
230 * limitation.
231 */
232 if (ip6_maxfragpackets < 0)
233 ;
234 else if (frag6_nfragpackets >= (u_int)ip6_maxfragpackets)
235 goto dropfrag;
236 frag6_nfragpackets++;
237 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE,
238 M_NOWAIT);
239 if (q6 == NULL)
240 goto dropfrag;
241 bzero(q6, sizeof(*q6));
242
243 frag6_insque(q6, &ip6q);
244
245 /* ip6q_nxt will be filled afterwards, from 1st fragment */
246 q6->ip6q_down = q6->ip6q_up = (struct ip6asfrag *)q6;
247#ifdef notyet
248 q6->ip6q_nxtp = (u_char *)nxtp;
249#endif
250 q6->ip6q_ident = ip6f->ip6f_ident;
251 q6->ip6q_arrive = 0; /* Is it used anywhere? */
252 q6->ip6q_ttl = IPV6_FRAGTTL;
253 q6->ip6q_src = ip6->ip6_src;
254 q6->ip6q_dst = ip6->ip6_dst;
255 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
256
257 q6->ip6q_nfrag = 0;
258 }
259
260 /*
261 * If it's the 1st fragment, record the length of the
262 * unfragmentable part and the next header of the fragment header.
263 */
264 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
265 if (fragoff == 0) {
266 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) -
267 sizeof(struct ip6_frag);
268 q6->ip6q_nxt = ip6f->ip6f_nxt;
269 }
270
271 /*
272 * Check that the reassembled packet would not exceed 65535 bytes
273 * in size.
274 * If it would exceed, discard the fragment and return an ICMP error.
275 */
276 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
277 if (q6->ip6q_unfrglen >= 0) {
278 /* The 1st fragment has already arrived. */
279 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
280 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
281 offset - sizeof(struct ip6_frag) +
282 offsetof(struct ip6_frag, ip6f_offlg));
283 IP6Q_UNLOCK();
284 return (IPPROTO_DONE);
285 }
286 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
287 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
288 offset - sizeof(struct ip6_frag) +
289 offsetof(struct ip6_frag, ip6f_offlg));
290 IP6Q_UNLOCK();
291 return (IPPROTO_DONE);
292 }
293 /*
294 * If it's the first fragment, do the above check for each
295 * fragment already stored in the reassembly queue.
296 */
297 if (fragoff == 0) {
298 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
299 af6 = af6dwn) {
300 af6dwn = af6->ip6af_down;
301
302 if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen >
303 IPV6_MAXPACKET) {
304 struct mbuf *merr = IP6_REASS_MBUF(af6);
305 struct ip6_hdr *ip6err;
306 int erroff = af6->ip6af_offset;
307
308 /* dequeue the fragment. */
309 frag6_deq(af6);
310 free(af6, M_FTABLE);
311
312 /* adjust pointer. */
313 ip6err = mtod(merr, struct ip6_hdr *);
314
315 /*
316 * Restore source and destination addresses
317 * in the erroneous IPv6 header.
318 */
319 ip6err->ip6_src = q6->ip6q_src;
320 ip6err->ip6_dst = q6->ip6q_dst;
321
322 icmp6_error(merr, ICMP6_PARAM_PROB,
323 ICMP6_PARAMPROB_HEADER,
324 erroff - sizeof(struct ip6_frag) +
325 offsetof(struct ip6_frag, ip6f_offlg));
326 }
327 }
328 }
329
330 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FTABLE,
331 M_NOWAIT);
332 if (ip6af == NULL)
333 goto dropfrag;
334 bzero(ip6af, sizeof(*ip6af));
335 ip6af->ip6af_head = ip6->ip6_flow;
336 ip6af->ip6af_len = ip6->ip6_plen;
337 ip6af->ip6af_nxt = ip6->ip6_nxt;
338 ip6af->ip6af_hlim = ip6->ip6_hlim;
339 ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG;
340 ip6af->ip6af_off = fragoff;
341 ip6af->ip6af_frglen = frgpartlen;
342 ip6af->ip6af_offset = offset;
343 IP6_REASS_MBUF(ip6af) = m;
344
345 if (first_frag) {
346 af6 = (struct ip6asfrag *)q6;
347 goto insert;
348 }
349
350 /*
351 * Handle ECN by comparing this segment with the first one;
352 * if CE is set, do not lose CE.
353 * drop if CE and not-ECT are mixed for the same packet.
354 */
355 ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
356 ecn0 = (ntohl(q6->ip6q_down->ip6af_head) >> 20) & IPTOS_ECN_MASK;
357 if (ecn == IPTOS_ECN_CE) {
358 if (ecn0 == IPTOS_ECN_NOTECT) {
359 free(ip6af, M_FTABLE);
360 goto dropfrag;
361 }
362 if (ecn0 != IPTOS_ECN_CE)
363 q6->ip6q_down->ip6af_head |= htonl(IPTOS_ECN_CE << 20);
364 }
365 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) {
366 free(ip6af, M_FTABLE);
367 goto dropfrag;
368 }
369
370 /*
371 * Find a segment which begins after this one does.
372 */
373 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
374 af6 = af6->ip6af_down)
375 if (af6->ip6af_off > ip6af->ip6af_off)
376 break;
377
378#if 0
379 /*
380 * If there is a preceding segment, it may provide some of
381 * our data already. If so, drop the data from the incoming
382 * segment. If it provides all of our data, drop us.
383 */
384 if (af6->ip6af_up != (struct ip6asfrag *)q6) {
385 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
386 - ip6af->ip6af_off;
387 if (i > 0) {
388 if (i >= ip6af->ip6af_frglen)
389 goto dropfrag;
390 m_adj(IP6_REASS_MBUF(ip6af), i);
391 ip6af->ip6af_off += i;
392 ip6af->ip6af_frglen -= i;
393 }
394 }
395
396 /*
397 * While we overlap succeeding segments trim them or,
398 * if they are completely covered, dequeue them.
399 */
400 while (af6 != (struct ip6asfrag *)q6 &&
401 ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) {
402 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
403 if (i < af6->ip6af_frglen) {
404 af6->ip6af_frglen -= i;
405 af6->ip6af_off += i;
406 m_adj(IP6_REASS_MBUF(af6), i);
407 break;
408 }
409 af6 = af6->ip6af_down;
410 m_freem(IP6_REASS_MBUF(af6->ip6af_up));
411 frag6_deq(af6->ip6af_up);
412 }
413#else
414 /*
415 * If the incoming framgent overlaps some existing fragments in
416 * the reassembly queue, drop it, since it is dangerous to override
417 * existing fragments from a security point of view.
418 * We don't know which fragment is the bad guy - here we trust
419 * fragment that came in earlier, with no real reason.
420 */
421 if (af6->ip6af_up != (struct ip6asfrag *)q6) {
422 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
423 - ip6af->ip6af_off;
424 if (i > 0) {
425#if 0 /* suppress the noisy log */
426 log(LOG_ERR, "%d bytes of a fragment from %s "
427 "overlaps the previous fragment\n",
428 i, ip6_sprintf(&q6->ip6q_src));
429#endif
430 free(ip6af, M_FTABLE);
431 goto dropfrag;
432 }
433 }
434 if (af6 != (struct ip6asfrag *)q6) {
435 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
436 if (i > 0) {
437#if 0 /* suppress the noisy log */
438 log(LOG_ERR, "%d bytes of a fragment from %s "
439 "overlaps the succeeding fragment",
440 i, ip6_sprintf(&q6->ip6q_src));
441#endif
442 free(ip6af, M_FTABLE);
443 goto dropfrag;
444 }
445 }
446#endif
447
448insert:
449
450 /*
451 * Stick new segment in its place;
452 * check for complete reassembly.
453 * Move to front of packet queue, as we are
454 * the most recently active fragmented packet.
455 */
456 frag6_enq(ip6af, af6->ip6af_up);
457 frag6_nfrags++;
458 q6->ip6q_nfrag++;
459#if 0 /* xxx */
460 if (q6 != ip6q.ip6q_next) {
461 frag6_remque(q6);
462 frag6_insque(q6, &ip6q);
463 }
464#endif
465 next = 0;
466 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
467 af6 = af6->ip6af_down) {
468 if (af6->ip6af_off != next) {
469 IP6Q_UNLOCK();
470 return IPPROTO_DONE;
471 }
472 next += af6->ip6af_frglen;
473 }
474 if (af6->ip6af_up->ip6af_mff) {
475 IP6Q_UNLOCK();
476 return IPPROTO_DONE;
477 }
478
479 /*
480 * Reassembly is complete; concatenate fragments.
481 */
482 ip6af = q6->ip6q_down;
483 t = m = IP6_REASS_MBUF(ip6af);
484 af6 = ip6af->ip6af_down;
485 frag6_deq(ip6af);
486 while (af6 != (struct ip6asfrag *)q6) {
487 af6dwn = af6->ip6af_down;
488 frag6_deq(af6);
489 while (t->m_next)
490 t = t->m_next;
491 t->m_next = IP6_REASS_MBUF(af6);
492 m_adj(t->m_next, af6->ip6af_offset);
493 free(af6, M_FTABLE);
494 af6 = af6dwn;
495 }
496
497 /* adjust offset to point where the original next header starts */
498 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
499 free(ip6af, M_FTABLE);
500 ip6 = mtod(m, struct ip6_hdr *);
501 ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr));
502 ip6->ip6_src = q6->ip6q_src;
503 ip6->ip6_dst = q6->ip6q_dst;
504 nxt = q6->ip6q_nxt;
505#ifdef notyet
506 *q6->ip6q_nxtp = (u_char)(nxt & 0xff);
507#endif
508
509 /*
510 * Delete frag6 header with as a few cost as possible.
511 */
512 if (offset < m->m_len) {
513 ovbcopy((caddr_t)ip6, (caddr_t)ip6 + sizeof(struct ip6_frag),
514 offset);
515 m->m_data += sizeof(struct ip6_frag);
516 m->m_len -= sizeof(struct ip6_frag);
517 } else {
518 /* this comes with no copy if the boundary is on cluster */
519 if ((t = m_split(m, offset, M_DONTWAIT)) == NULL) {
520 frag6_remque(q6);
521 frag6_nfrags -= q6->ip6q_nfrag;
522 free(q6, M_FTABLE);
523 frag6_nfragpackets--;
524 goto dropfrag;
525 }
526 m_adj(t, sizeof(struct ip6_frag));
527 m_cat(m, t);
528 }
529
530 /*
531 * Store NXT to the original.
532 */
533 {
534 char *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */
535 *prvnxtp = nxt;
536 }
537
538 frag6_remque(q6);
539 frag6_nfrags -= q6->ip6q_nfrag;
540 free(q6, M_FTABLE);
541 frag6_nfragpackets--;
542
543 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
544 int plen = 0;
545 for (t = m; t; t = t->m_next)
546 plen += t->m_len;
547 m->m_pkthdr.len = plen;
548 }
549
550 ip6stat.ip6s_reassembled++;
551 in6_ifstat_inc(dstifp, ifs6_reass_ok);
552
553 /*
554 * Tell launch routine the next header
555 */
556
557 *mp = m;
558 *offp = offset;
559
560 IP6Q_UNLOCK();
561 return nxt;
562
563 dropfrag:
564 IP6Q_UNLOCK();
565 in6_ifstat_inc(dstifp, ifs6_reass_fail);
566 ip6stat.ip6s_fragdropped++;
567 m_freem(m);
568 return IPPROTO_DONE;
569}
570
571/*
572 * Free a fragment reassembly header and all
573 * associated datagrams.
574 */
575void
576frag6_freef(q6)
577 struct ip6q *q6;
578{
579 struct ip6asfrag *af6, *down6;
580
581 IP6Q_LOCK_ASSERT();
582
583 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
584 af6 = down6) {
585 struct mbuf *m = IP6_REASS_MBUF(af6);
586
587 down6 = af6->ip6af_down;
588 frag6_deq(af6);
589
590 /*
591 * Return ICMP time exceeded error for the 1st fragment.
592 * Just free other fragments.
593 */
594 if (af6->ip6af_off == 0) {
595 struct ip6_hdr *ip6;
596
597 /* adjust pointer */
598 ip6 = mtod(m, struct ip6_hdr *);
599
600 /* restore source and destination addresses */
601 ip6->ip6_src = q6->ip6q_src;
602 ip6->ip6_dst = q6->ip6q_dst;
603
604 icmp6_error(m, ICMP6_TIME_EXCEEDED,
605 ICMP6_TIME_EXCEED_REASSEMBLY, 0);
606 } else
607 m_freem(m);
608 free(af6, M_FTABLE);
609 }
610 frag6_remque(q6);
611 frag6_nfrags -= q6->ip6q_nfrag;
612 free(q6, M_FTABLE);
613 frag6_nfragpackets--;
614}
615
616/*
617 * Put an ip fragment on a reassembly chain.
618 * Like insque, but pointers in middle of structure.
619 */
620void
621frag6_enq(af6, up6)
622 struct ip6asfrag *af6, *up6;
623{
624
625 IP6Q_LOCK_ASSERT();
626
627 af6->ip6af_up = up6;
628 af6->ip6af_down = up6->ip6af_down;
629 up6->ip6af_down->ip6af_up = af6;
630 up6->ip6af_down = af6;
631}
632
633/*
634 * To frag6_enq as remque is to insque.
635 */
636void
637frag6_deq(af6)
638 struct ip6asfrag *af6;
639{
640
641 IP6Q_LOCK_ASSERT();
642
643 af6->ip6af_up->ip6af_down = af6->ip6af_down;
644 af6->ip6af_down->ip6af_up = af6->ip6af_up;
645}
646
647void
648frag6_insque(new, old)
649 struct ip6q *new, *old;
650{
651
652 IP6Q_LOCK_ASSERT();
653
654 new->ip6q_prev = old;
655 new->ip6q_next = old->ip6q_next;
656 old->ip6q_next->ip6q_prev= new;
657 old->ip6q_next = new;
658}
659
660void
661frag6_remque(p6)
662 struct ip6q *p6;
663{
664
665 IP6Q_LOCK_ASSERT();
666
667 p6->ip6q_prev->ip6q_next = p6->ip6q_next;
668 p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
669}
670
671/*
672 * IPv6 reassembling timer processing;
673 * if a timer expires on a reassembly
674 * queue, discard it.
675 */
676void
677frag6_slowtimo()
678{
679 struct ip6q *q6;
680 int s = splnet();
681
682 IP6Q_LOCK();
683 q6 = ip6q.ip6q_next;
684 if (q6)
685 while (q6 != &ip6q) {
686 --q6->ip6q_ttl;
687 q6 = q6->ip6q_next;
688 if (q6->ip6q_prev->ip6q_ttl == 0) {
689 ip6stat.ip6s_fragtimeout++;
690 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
691 frag6_freef(q6->ip6q_prev);
692 }
693 }
694 /*
695 * If we are over the maximum number of fragments
696 * (due to the limit being lowered), drain off
697 * enough to get down to the new limit.
698 */
699 while (frag6_nfragpackets > (u_int)ip6_maxfragpackets &&
700 ip6q.ip6q_prev) {
701 ip6stat.ip6s_fragoverflow++;
702 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
703 frag6_freef(ip6q.ip6q_prev);
704 }
705 IP6Q_UNLOCK();
706
707#if 0
708 /*
709 * Routing changes might produce a better route than we last used;
710 * make sure we notice eventually, even if forwarding only for one
711 * destination and the cache is never replaced.
712 */
713 if (ip6_forward_rt.ro_rt) {
714 RTFREE(ip6_forward_rt.ro_rt);
715 ip6_forward_rt.ro_rt = 0;
716 }
717 if (ipsrcchk_rt.ro_rt) {
718 RTFREE(ipsrcchk_rt.ro_rt);
719 ipsrcchk_rt.ro_rt = 0;
720 }
721#endif
722
723 splx(s);
724}
725
726/*
727 * Drain off all datagram fragments.
728 */
729void
730frag6_drain()
731{
732
733 if (IP6Q_TRYLOCK() == 0)
734 return;
735 while (ip6q.ip6q_next != &ip6q) {
736 ip6stat.ip6s_fragdropped++;
737 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
738 frag6_freef(ip6q.ip6q_next);
739 }
740 IP6Q_UNLOCK();
741}
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