1 /* $OpenBSD: frag6.c,v 1.21+1.31 2003/10/01 21:41:05 itojun Exp $ */
2 /* $KAME: frag6.c,v 1.40 2002/05/27 21:40:31 itojun Exp $ */
3
4 /*
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 <dev/rndvar.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
65 static void frag6_enq(struct ip6asfrag *, struct ip6asfrag *);
66 static void frag6_deq(struct ip6asfrag *);
67 static void frag6_insque(struct ip6q *, struct ip6q *);
68 static void frag6_remque(struct ip6q *);
69 static void frag6_freef(struct ip6q *);
70
71 static int ip6q_locked;
72 u_int frag6_nfragpackets;
73 u_int frag6_nfrags;
74 struct ip6q ip6q; /* ip6 reassemble queue */
75
76 static __inline int ip6q_lock_try(void);
77 static __inline void ip6q_unlock(void);
78
79 static __inline int
ip6q_lock_try()80 ip6q_lock_try()
81 {
82 int s;
83
84 s = splimp();
85 if (ip6q_locked) {
86 splx(s);
87 return (0);
88 }
89 ip6q_locked = 1;
90 splx(s);
91 return (1);
92 }
93
94 static __inline void
ip6q_unlock()95 ip6q_unlock()
96 {
97 int s;
98
99 s = splimp();
100 ip6q_locked = 0;
101 splx(s);
102 }
103
104 #ifdef DIAGNOSTIC
105 #define IP6Q_LOCK() \
106 do { \
107 if (ip6q_lock_try() == 0) { \
108 printf("%s:%d: ip6q already locked\n", __FILE__, __LINE__); \
109 panic("ip6q_lock"); \
110 } \
111 } while (0)
112 #define IP6Q_LOCK_CHECK() \
113 do { \
114 if (ip6q_locked == 0) { \
115 printf("%s:%d: ip6q lock not held\n", __FILE__, __LINE__); \
116 panic("ip6q lock check"); \
117 } \
118 } while (0)
119 #else
120 #define IP6Q_LOCK() (void) ip6q_lock_try()
121 #define IP6Q_LOCK_CHECK() /* nothing */
122 #endif
123
124 #define IP6Q_UNLOCK() ip6q_unlock()
125
126 #ifndef offsetof /* XXX */
127 #define offsetof(type, member) ((size_t)(&((type *)0)->member))
128 #endif
129
130 /*
131 * Initialise reassembly queue and fragment identifier.
132 */
133 void
frag6_init()134 frag6_init()
135 {
136
137 ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q;
138 }
139
140 /*
141 * In RFC2460, fragment and reassembly rule do not agree with each other,
142 * in terms of next header field handling in fragment header.
143 * While the sender will use the same value for all of the fragmented packets,
144 * receiver is suggested not to check the consistency.
145 *
146 * fragment rule (p20):
147 * (2) A Fragment header containing:
148 * The Next Header value that identifies the first header of
149 * the Fragmentable Part of the original packet.
150 * -> next header field is same for all fragments
151 *
152 * reassembly rule (p21):
153 * The Next Header field of the last header of the Unfragmentable
154 * Part is obtained from the Next Header field of the first
155 * fragment's Fragment header.
156 * -> should grab it from the first fragment only
157 *
158 * The following note also contradicts with fragment rule - noone is going to
159 * send different fragment with different next header field.
160 *
161 * additional note (p22):
162 * The Next Header values in the Fragment headers of different
163 * fragments of the same original packet may differ. Only the value
164 * from the Offset zero fragment packet is used for reassembly.
165 * -> should grab it from the first fragment only
166 *
167 * There is no explicit reason given in the RFC. Historical reason maybe?
168 */
169 /*
170 * Fragment input
171 */
172 int
frag6_input(mp,offp,proto)173 frag6_input(mp, offp, proto)
174 struct mbuf **mp;
175 int *offp, proto;
176 {
177 struct mbuf *m = *mp, *t;
178 struct ip6_hdr *ip6;
179 struct ip6_frag *ip6f;
180 struct ip6q *q6;
181 struct ip6asfrag *af6, *ip6af, *af6dwn;
182 int offset = *offp, nxt, i, next;
183 int first_frag = 0;
184 int fragoff, frgpartlen; /* must be larger than u_int16_t */
185 struct ifnet *dstifp;
186 #ifdef IN6_IFSTAT_STRICT
187 static struct route_in6 ro;
188 struct sockaddr_in6 *dst;
189 #endif
190 u_int8_t ecn, ecn0;
191
192 ip6 = mtod(m, struct ip6_hdr *);
193 IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
194 if (ip6f == NULL)
195 return IPPROTO_DONE;
196
197 dstifp = NULL;
198 #ifdef IN6_IFSTAT_STRICT
199 /* find the destination interface of the packet. */
200 dst = (struct sockaddr_in6 *)&ro.ro_dst;
201 if (ro.ro_rt
202 && ((ro.ro_rt->rt_flags & RTF_UP) == 0
203 || !IN6_ARE_ADDR_EQUAL(&dst->sin6_addr, &ip6->ip6_dst))) {
204 RTFREE(ro.ro_rt);
205 ro.ro_rt = (struct rtentry *)0;
206 }
207 if (ro.ro_rt == NULL) {
208 bzero(dst, sizeof(*dst));
209 dst->sin6_family = AF_INET6;
210 dst->sin6_len = sizeof(struct sockaddr_in6);
211 dst->sin6_addr = ip6->ip6_dst;
212 }
213
214 rtalloc((struct route *)&ro);
215
216 if (ro.ro_rt != NULL && ro.ro_rt->rt_ifa != NULL)
217 dstifp = ((struct in6_ifaddr *)ro.ro_rt->rt_ifa)->ia_ifp;
218 #else
219 /* we are violating the spec, this is not the destination interface */
220 if ((m->m_flags & M_PKTHDR) != 0)
221 dstifp = m->m_pkthdr.rcvif;
222 #endif
223
224 /* jumbo payload can't contain a fragment header */
225 if (ip6->ip6_plen == 0) {
226 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
227 in6_ifstat_inc(dstifp, ifs6_reass_fail);
228 return IPPROTO_DONE;
229 }
230
231 /*
232 * check whether fragment packet's fragment length is
233 * multiple of 8 octets.
234 * sizeof(struct ip6_frag) == 8
235 * sizeof(struct ip6_hdr) = 40
236 */
237 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
238 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
239 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
240 offsetof(struct ip6_hdr, ip6_plen));
241 in6_ifstat_inc(dstifp, ifs6_reass_fail);
242 return IPPROTO_DONE;
243 }
244
245 ip6stat.ip6s_fragments++;
246 in6_ifstat_inc(dstifp, ifs6_reass_reqd);
247
248 /* offset now points to data portion */
249 offset += sizeof(struct ip6_frag);
250
251 IP6Q_LOCK();
252
253 /*
254 * Enforce upper bound on number of fragments.
255 * If maxfrag is 0, never accept fragments.
256 * If maxfrag is -1, accept all fragments without limitation.
257 */
258 if (ip6_maxfrags < 0)
259 ;
260 else if (frag6_nfrags >= (u_int)ip6_maxfrags)
261 goto dropfrag;
262
263 for (q6 = ip6q.ip6q_next; q6 != &ip6q; q6 = q6->ip6q_next)
264 if (ip6f->ip6f_ident == q6->ip6q_ident &&
265 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
266 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst))
267 break;
268
269 if (q6 == &ip6q) {
270 /*
271 * the first fragment to arrive, create a reassembly queue.
272 */
273 first_frag = 1;
274
275 /*
276 * Enforce upper bound on number of fragmented packets
277 * for which we attempt reassembly;
278 * If maxfragpackets is 0, never accept fragments.
279 * If maxfragpackets is -1, accept all fragments without
280 * limitation.
281 */
282 if (ip6_maxfragpackets < 0)
283 ;
284 else if (frag6_nfragpackets >= (u_int)ip6_maxfragpackets)
285 goto dropfrag;
286 frag6_nfragpackets++;
287 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE,
288 M_DONTWAIT);
289 if (q6 == NULL)
290 goto dropfrag;
291 bzero(q6, sizeof(*q6));
292
293 frag6_insque(q6, &ip6q);
294
295 /* ip6q_nxt will be filled afterwards, from 1st fragment */
296 q6->ip6q_down = q6->ip6q_up = (struct ip6asfrag *)q6;
297 #ifdef notyet
298 q6->ip6q_nxtp = (u_char *)nxtp;
299 #endif
300 q6->ip6q_ident = ip6f->ip6f_ident;
301 q6->ip6q_arrive = 0; /* Is it used anywhere? */
302 q6->ip6q_ttl = IPV6_FRAGTTL;
303 q6->ip6q_src = ip6->ip6_src;
304 q6->ip6q_dst = ip6->ip6_dst;
305 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
306
307 q6->ip6q_nfrag = 0;
308 }
309
310 /*
311 * If it's the 1st fragment, record the length of the
312 * unfragmentable part and the next header of the fragment header.
313 */
314 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
315 if (fragoff == 0) {
316 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) -
317 sizeof(struct ip6_frag);
318 q6->ip6q_nxt = ip6f->ip6f_nxt;
319 }
320
321 /*
322 * Check that the reassembled packet would not exceed 65535 bytes
323 * in size.
324 * If it would exceed, discard the fragment and return an ICMP error.
325 */
326 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
327 if (q6->ip6q_unfrglen >= 0) {
328 /* The 1st fragment has already arrived. */
329 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
330 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
331 offset - sizeof(struct ip6_frag) +
332 offsetof(struct ip6_frag, ip6f_offlg));
333 IP6Q_UNLOCK();
334 return (IPPROTO_DONE);
335 }
336 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
337 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
338 offset - sizeof(struct ip6_frag) +
339 offsetof(struct ip6_frag, ip6f_offlg));
340 IP6Q_UNLOCK();
341 return (IPPROTO_DONE);
342 }
343 /*
344 * If it's the first fragment, do the above check for each
345 * fragment already stored in the reassembly queue.
346 */
347 if (fragoff == 0) {
348 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
349 af6 = af6dwn) {
350 af6dwn = af6->ip6af_down;
351
352 if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen >
353 IPV6_MAXPACKET) {
354 struct mbuf *merr = IP6_REASS_MBUF(af6);
355 struct ip6_hdr *ip6err;
356 int erroff = af6->ip6af_offset;
357
358 /* dequeue the fragment. */
359 frag6_deq(af6);
360 free(af6, M_FTABLE);
361
362 /* adjust pointer. */
363 ip6err = mtod(merr, struct ip6_hdr *);
364
365 /*
366 * Restore source and destination addresses
367 * in the erroneous IPv6 header.
368 */
369 ip6err->ip6_src = q6->ip6q_src;
370 ip6err->ip6_dst = q6->ip6q_dst;
371
372 icmp6_error(merr, ICMP6_PARAM_PROB,
373 ICMP6_PARAMPROB_HEADER,
374 erroff - sizeof(struct ip6_frag) +
375 offsetof(struct ip6_frag, ip6f_offlg));
376 }
377 }
378 }
379
380 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FTABLE,
381 M_DONTWAIT);
382 if (ip6af == NULL)
383 goto dropfrag;
384 bzero(ip6af, sizeof(*ip6af));
385 ip6af->ip6af_head = ip6->ip6_flow;
386 ip6af->ip6af_len = ip6->ip6_plen;
387 ip6af->ip6af_nxt = ip6->ip6_nxt;
388 ip6af->ip6af_hlim = ip6->ip6_hlim;
389 ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG;
390 ip6af->ip6af_off = fragoff;
391 ip6af->ip6af_frglen = frgpartlen;
392 ip6af->ip6af_offset = offset;
393 IP6_REASS_MBUF(ip6af) = m;
394
395 if (first_frag) {
396 af6 = (struct ip6asfrag *)q6;
397 goto insert;
398 }
399
400 /*
401 * Handle ECN by comparing this segment with the first one;
402 * if CE is set, do not lose CE.
403 * drop if CE and not-ECT are mixed for the same packet.
404 */
405 ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
406 ecn0 = (ntohl(q6->ip6q_down->ip6af_head) >> 20) & IPTOS_ECN_MASK;
407 if (ecn == IPTOS_ECN_CE) {
408 if (ecn0 == IPTOS_ECN_NOTECT) {
409 free(ip6af, M_FTABLE);
410 goto dropfrag;
411 }
412 if (ecn0 != IPTOS_ECN_CE)
413 q6->ip6q_down->ip6af_head |= htonl(IPTOS_ECN_CE << 20);
414 }
415 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) {
416 free(ip6af, M_FTABLE);
417 goto dropfrag;
418 }
419
420 /*
421 * Find a segment which begins after this one does.
422 */
423 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
424 af6 = af6->ip6af_down)
425 if (af6->ip6af_off > ip6af->ip6af_off)
426 break;
427
428 #if 0
429 /*
430 * If there is a preceding segment, it may provide some of
431 * our data already. If so, drop the data from the incoming
432 * segment. If it provides all of our data, drop us.
433 */
434 if (af6->ip6af_up != (struct ip6asfrag *)q6) {
435 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
436 - ip6af->ip6af_off;
437 if (i > 0) {
438 if (i >= ip6af->ip6af_frglen)
439 goto dropfrag;
440 m_adj(IP6_REASS_MBUF(ip6af), i);
441 ip6af->ip6af_off += i;
442 ip6af->ip6af_frglen -= i;
443 }
444 }
445
446 /*
447 * While we overlap succeeding segments trim them or,
448 * if they are completely covered, dequeue them.
449 */
450 while (af6 != (struct ip6asfrag *)q6 &&
451 ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) {
452 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
453 if (i < af6->ip6af_frglen) {
454 af6->ip6af_frglen -= i;
455 af6->ip6af_off += i;
456 m_adj(IP6_REASS_MBUF(af6), i);
457 break;
458 }
459 af6 = af6->ip6af_down;
460 m_freem(IP6_REASS_MBUF(af6->ip6af_up));
461 frag6_deq(af6->ip6af_up);
462 }
463 #else
464 /*
465 * If the incoming framgent overlaps some existing fragments in
466 * the reassembly queue, drop it, since it is dangerous to override
467 * existing fragments from a security point of view.
468 * We don't know which fragment is the bad guy - here we trust
469 * fragment that came in earlier, with no real reason.
470 */
471 if (af6->ip6af_up != (struct ip6asfrag *)q6) {
472 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
473 - ip6af->ip6af_off;
474 if (i > 0) {
475 #if 0 /* suppress the noisy log */
476 log(LOG_ERR, "%d bytes of a fragment from %s "
477 "overlaps the previous fragment\n",
478 i, ip6_sprintf(&q6->ip6q_src));
479 #endif
480 free(ip6af, M_FTABLE);
481 goto dropfrag;
482 }
483 }
484 if (af6 != (struct ip6asfrag *)q6) {
485 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
486 if (i > 0) {
487 #if 0 /* suppress the noisy log */
488 log(LOG_ERR, "%d bytes of a fragment from %s "
489 "overlaps the succeeding fragment",
490 i, ip6_sprintf(&q6->ip6q_src));
491 #endif
492 free(ip6af, M_FTABLE);
493 goto dropfrag;
494 }
495 }
496 #endif
497
498 insert:
499
500 /*
501 * Stick new segment in its place;
502 * check for complete reassembly.
503 * Move to front of packet queue, as we are
504 * the most recently active fragmented packet.
505 */
506 frag6_enq(ip6af, af6->ip6af_up);
507 frag6_nfrags++;
508 q6->ip6q_nfrag++;
509 #if 0 /* xxx */
510 if (q6 != ip6q.ip6q_next) {
511 frag6_remque(q6);
512 frag6_insque(q6, &ip6q);
513 }
514 #endif
515 next = 0;
516 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
517 af6 = af6->ip6af_down) {
518 if (af6->ip6af_off != next) {
519 IP6Q_UNLOCK();
520 return IPPROTO_DONE;
521 }
522 next += af6->ip6af_frglen;
523 }
524 if (af6->ip6af_up->ip6af_mff) {
525 IP6Q_UNLOCK();
526 return IPPROTO_DONE;
527 }
528
529 /*
530 * Reassembly is complete; concatenate fragments.
531 */
532 ip6af = q6->ip6q_down;
533 t = m = IP6_REASS_MBUF(ip6af);
534 af6 = ip6af->ip6af_down;
535 frag6_deq(ip6af);
536 while (af6 != (struct ip6asfrag *)q6) {
537 af6dwn = af6->ip6af_down;
538 frag6_deq(af6);
539 while (t->m_next)
540 t = t->m_next;
541 t->m_next = IP6_REASS_MBUF(af6);
542 m_adj(t->m_next, af6->ip6af_offset);
543 free(af6, M_FTABLE);
544 af6 = af6dwn;
545 }
546
547 /* adjust offset to point where the original next header starts */
548 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
549 free(ip6af, M_FTABLE);
550 ip6 = mtod(m, struct ip6_hdr *);
551 ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr));
552 ip6->ip6_src = q6->ip6q_src;
553 ip6->ip6_dst = q6->ip6q_dst;
554 nxt = q6->ip6q_nxt;
555 #ifdef notyet
556 *q6->ip6q_nxtp = (u_char)(nxt & 0xff);
557 #endif
558
559 /* Delete frag6 header */
560 if (m->m_len >= offset + sizeof(struct ip6_frag)) {
561 /* This is the only possible case with !PULLDOWN_TEST */
562 ovbcopy((caddr_t)ip6, (caddr_t)ip6 + sizeof(struct ip6_frag),
563 offset);
564 m->m_data += sizeof(struct ip6_frag);
565 m->m_len -= sizeof(struct ip6_frag);
566 } else {
567 /* this comes with no copy if the boundary is on cluster */
568 if ((t = m_split(m, offset, M_DONTWAIT)) == NULL) {
569 frag6_remque(q6);
570 frag6_nfrags -= q6->ip6q_nfrag;
571 free(q6, M_FTABLE);
572 frag6_nfragpackets--;
573 goto dropfrag;
574 }
575 m_adj(t, sizeof(struct ip6_frag));
576 m_cat(m, t);
577 }
578
579 /*
580 * Store NXT to the original.
581 */
582 {
583 u_int8_t *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */
584 *prvnxtp = nxt;
585 }
586
587 frag6_remque(q6);
588 frag6_nfrags -= q6->ip6q_nfrag;
589 free(q6, M_FTABLE);
590 frag6_nfragpackets--;
591
592 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
593 int plen = 0;
594 for (t = m; t; t = t->m_next)
595 plen += t->m_len;
596 m->m_pkthdr.len = plen;
597 }
598
599 ip6stat.ip6s_reassembled++;
600 in6_ifstat_inc(dstifp, ifs6_reass_ok);
601
602 /*
603 * Tell launch routine the next header
604 */
605
606 *mp = m;
607 *offp = offset;
608
609 IP6Q_UNLOCK();
610 return nxt;
611
612 dropfrag:
613 in6_ifstat_inc(dstifp, ifs6_reass_fail);
614 ip6stat.ip6s_fragdropped++;
615 m_freem(m);
616 IP6Q_UNLOCK();
617 return IPPROTO_DONE;
618 }
619
620 /*
621 * Free a fragment reassembly header and all
622 * associated datagrams.
623 */
624 void
frag6_freef(q6)625 frag6_freef(q6)
626 struct ip6q *q6;
627 {
628 struct ip6asfrag *af6, *down6;
629
630 IP6Q_LOCK_CHECK();
631
632 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
633 af6 = down6) {
634 struct mbuf *m = IP6_REASS_MBUF(af6);
635
636 down6 = af6->ip6af_down;
637 frag6_deq(af6);
638
639 /*
640 * Return ICMP time exceeded error for the 1st fragment.
641 * Just free other fragments.
642 */
643 if (af6->ip6af_off == 0) {
644 struct ip6_hdr *ip6;
645
646 /* adjust pointer */
647 ip6 = mtod(m, struct ip6_hdr *);
648
649 /* restoure source and destination addresses */
650 ip6->ip6_src = q6->ip6q_src;
651 ip6->ip6_dst = q6->ip6q_dst;
652
653 icmp6_error(m, ICMP6_TIME_EXCEEDED,
654 ICMP6_TIME_EXCEED_REASSEMBLY, 0);
655 } else
656 m_freem(m);
657 free(af6, M_FTABLE);
658 }
659 frag6_remque(q6);
660 frag6_nfrags -= q6->ip6q_nfrag;
661 free(q6, M_FTABLE);
662 frag6_nfragpackets--;
663 }
664
665 /*
666 * Put an ip fragment on a reassembly chain.
667 * Like insque, but pointers in middle of structure.
668 */
669 void
frag6_enq(af6,up6)670 frag6_enq(af6, up6)
671 struct ip6asfrag *af6, *up6;
672 {
673
674 IP6Q_LOCK_CHECK();
675
676 af6->ip6af_up = up6;
677 af6->ip6af_down = up6->ip6af_down;
678 up6->ip6af_down->ip6af_up = af6;
679 up6->ip6af_down = af6;
680 }
681
682 /*
683 * To frag6_enq as remque is to insque.
684 */
685 void
frag6_deq(af6)686 frag6_deq(af6)
687 struct ip6asfrag *af6;
688 {
689
690 IP6Q_LOCK_CHECK();
691
692 af6->ip6af_up->ip6af_down = af6->ip6af_down;
693 af6->ip6af_down->ip6af_up = af6->ip6af_up;
694 }
695
696 void
frag6_insque(new,old)697 frag6_insque(new, old)
698 struct ip6q *new, *old;
699 {
700
701 IP6Q_LOCK_CHECK();
702
703 new->ip6q_prev = old;
704 new->ip6q_next = old->ip6q_next;
705 old->ip6q_next->ip6q_prev= new;
706 old->ip6q_next = new;
707 }
708
709 void
frag6_remque(p6)710 frag6_remque(p6)
711 struct ip6q *p6;
712 {
713
714 IP6Q_LOCK_CHECK();
715
716 p6->ip6q_prev->ip6q_next = p6->ip6q_next;
717 p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
718 }
719
720 /*
721 * IPv6 reassembling timer processing;
722 * if a timer expires on a reassembly
723 * queue, discard it.
724 */
725 void
frag6_slowtimo()726 frag6_slowtimo()
727 {
728 struct ip6q *q6;
729 int s = splsoftnet();
730
731 IP6Q_LOCK();
732 q6 = ip6q.ip6q_next;
733 if (q6)
734 while (q6 != &ip6q) {
735 --q6->ip6q_ttl;
736 q6 = q6->ip6q_next;
737 if (q6->ip6q_prev->ip6q_ttl == 0) {
738 ip6stat.ip6s_fragtimeout++;
739 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
740 frag6_freef(q6->ip6q_prev);
741 }
742 }
743 /*
744 * If we are over the maximum number of fragments
745 * (due to the limit being lowered), drain off
746 * enough to get down to the new limit.
747 */
748 while (frag6_nfragpackets > (u_int)ip6_maxfragpackets &&
749 ip6q.ip6q_prev) {
750 ip6stat.ip6s_fragoverflow++;
751 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
752 frag6_freef(ip6q.ip6q_prev);
753 }
754 IP6Q_UNLOCK();
755
756 #if 0
757 /*
758 * Routing changes might produce a better route than we last used;
759 * make sure we notice eventually, even if forwarding only for one
760 * destination and the cache is never replaced.
761 */
762 if (ip6_forward_rt.ro_rt) {
763 RTFREE(ip6_forward_rt.ro_rt);
764 ip6_forward_rt.ro_rt = 0;
765 }
766 if (ipsrcchk_rt.ro_rt) {
767 RTFREE(ipsrcchk_rt.ro_rt);
768 ipsrcchk_rt.ro_rt = 0;
769 }
770 #endif
771
772 splx(s);
773 }
774
775 /*
776 * Drain off all datagram fragments.
777 */
778 void
frag6_drain()779 frag6_drain()
780 {
781
782 if (ip6q_lock_try() == 0)
783 return;
784 while (ip6q.ip6q_next != &ip6q) {
785 ip6stat.ip6s_fragdropped++;
786 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
787 frag6_freef(ip6q.ip6q_next);
788 }
789 IP6Q_UNLOCK();
790 }
791