FreeBSD/Linux Kernel Cross Reference
sys/netinet6/frag6.c
1 /*-
2 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the project nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $KAME: frag6.c,v 1.33 2002/01/07 11:34:48 kjc Exp $
30 */
31
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD: src/sys/netinet6/frag6.c,v 1.41 2008/12/02 21:37:28 bz Exp $");
34
35 #include "opt_mac.h"
36
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/malloc.h>
40 #include <sys/mbuf.h>
41 #include <sys/domain.h>
42 #include <sys/protosw.h>
43 #include <sys/socket.h>
44 #include <sys/errno.h>
45 #include <sys/time.h>
46 #include <sys/kernel.h>
47 #include <sys/syslog.h>
48 #include <sys/vimage.h>
49
50 #include <net/if.h>
51 #include <net/route.h>
52
53 #include <netinet/in.h>
54 #include <netinet/in_var.h>
55 #include <netinet/ip6.h>
56 #include <netinet6/ip6_var.h>
57 #include <netinet/icmp6.h>
58 #include <netinet/in_systm.h> /* for ECN definitions */
59 #include <netinet/ip.h> /* for ECN definitions */
60 #include <netinet6/vinet6.h>
61
62 #include <security/mac/mac_framework.h>
63
64 /*
65 * Define it to get a correct behavior on per-interface statistics.
66 * You will need to perform an extra routing table lookup, per fragment,
67 * to do it. This may, or may not be, a performance hit.
68 */
69 #define IN6_IFSTAT_STRICT
70
71 static void frag6_enq(struct ip6asfrag *, struct ip6asfrag *);
72 static void frag6_deq(struct ip6asfrag *);
73 static void frag6_insque(struct ip6q *, struct ip6q *);
74 static void frag6_remque(struct ip6q *);
75 static void frag6_freef(struct ip6q *);
76
77 static struct mtx ip6qlock;
78 /*
79 * These fields all protected by ip6qlock.
80 */
81 #ifdef VIMAGE_GLOBALS
82 static u_int frag6_nfragpackets;
83 static u_int frag6_nfrags;
84 static struct ip6q ip6q; /* ip6 reassemble queue */
85 #endif
86
87 #define IP6Q_LOCK_INIT() mtx_init(&ip6qlock, "ip6qlock", NULL, MTX_DEF);
88 #define IP6Q_LOCK() mtx_lock(&ip6qlock)
89 #define IP6Q_TRYLOCK() mtx_trylock(&ip6qlock)
90 #define IP6Q_LOCK_ASSERT() mtx_assert(&ip6qlock, MA_OWNED)
91 #define IP6Q_UNLOCK() mtx_unlock(&ip6qlock)
92
93 static MALLOC_DEFINE(M_FTABLE, "fragment", "fragment reassembly header");
94
95 /*
96 * Initialise reassembly queue and fragment identifier.
97 */
98 static void
99 frag6_change(void *tag)
100 {
101 INIT_VNET_INET6(curvnet);
102
103 V_ip6_maxfragpackets = nmbclusters / 4;
104 V_ip6_maxfrags = nmbclusters / 4;
105 }
106
107 void
108 frag6_init(void)
109 {
110 INIT_VNET_INET6(curvnet);
111
112 V_ip6_maxfragpackets = nmbclusters / 4;
113 V_ip6_maxfrags = nmbclusters / 4;
114 EVENTHANDLER_REGISTER(nmbclusters_change,
115 frag6_change, NULL, EVENTHANDLER_PRI_ANY);
116
117 IP6Q_LOCK_INIT();
118
119 V_ip6q.ip6q_next = V_ip6q.ip6q_prev = &V_ip6q;
120 }
121
122 /*
123 * In RFC2460, fragment and reassembly rule do not agree with each other,
124 * in terms of next header field handling in fragment header.
125 * While the sender will use the same value for all of the fragmented packets,
126 * receiver is suggested not to check the consistency.
127 *
128 * fragment rule (p20):
129 * (2) A Fragment header containing:
130 * The Next Header value that identifies the first header of
131 * the Fragmentable Part of the original packet.
132 * -> next header field is same for all fragments
133 *
134 * reassembly rule (p21):
135 * The Next Header field of the last header of the Unfragmentable
136 * Part is obtained from the Next Header field of the first
137 * fragment's Fragment header.
138 * -> should grab it from the first fragment only
139 *
140 * The following note also contradicts with fragment rule - noone is going to
141 * send different fragment with different next header field.
142 *
143 * additional note (p22):
144 * The Next Header values in the Fragment headers of different
145 * fragments of the same original packet may differ. Only the value
146 * from the Offset zero fragment packet is used for reassembly.
147 * -> should grab it from the first fragment only
148 *
149 * There is no explicit reason given in the RFC. Historical reason maybe?
150 */
151 /*
152 * Fragment input
153 */
154 int
155 frag6_input(struct mbuf **mp, int *offp, int proto)
156 {
157 INIT_VNET_INET6(curvnet);
158 struct mbuf *m = *mp, *t;
159 struct ip6_hdr *ip6;
160 struct ip6_frag *ip6f;
161 struct ip6q *q6;
162 struct ip6asfrag *af6, *ip6af, *af6dwn;
163 #ifdef IN6_IFSTAT_STRICT
164 struct in6_ifaddr *ia;
165 #endif
166 int offset = *offp, nxt, i, next;
167 int first_frag = 0;
168 int fragoff, frgpartlen; /* must be larger than u_int16_t */
169 struct ifnet *dstifp;
170 u_int8_t ecn, ecn0;
171 #if 0
172 char ip6buf[INET6_ADDRSTRLEN];
173 #endif
174
175 ip6 = mtod(m, struct ip6_hdr *);
176 #ifndef PULLDOWN_TEST
177 IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE);
178 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
179 #else
180 IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
181 if (ip6f == NULL)
182 return (IPPROTO_DONE);
183 #endif
184
185 dstifp = NULL;
186 #ifdef IN6_IFSTAT_STRICT
187 /* find the destination interface of the packet. */
188 if ((ia = ip6_getdstifaddr(m)) != NULL)
189 dstifp = ia->ia_ifp;
190 #else
191 /* we are violating the spec, this is not the destination interface */
192 if ((m->m_flags & M_PKTHDR) != 0)
193 dstifp = m->m_pkthdr.rcvif;
194 #endif
195
196 /* jumbo payload can't contain a fragment header */
197 if (ip6->ip6_plen == 0) {
198 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
199 in6_ifstat_inc(dstifp, ifs6_reass_fail);
200 return IPPROTO_DONE;
201 }
202
203 /*
204 * check whether fragment packet's fragment length is
205 * multiple of 8 octets.
206 * sizeof(struct ip6_frag) == 8
207 * sizeof(struct ip6_hdr) = 40
208 */
209 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
210 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
211 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
212 offsetof(struct ip6_hdr, ip6_plen));
213 in6_ifstat_inc(dstifp, ifs6_reass_fail);
214 return IPPROTO_DONE;
215 }
216
217 V_ip6stat.ip6s_fragments++;
218 in6_ifstat_inc(dstifp, ifs6_reass_reqd);
219
220 /* offset now points to data portion */
221 offset += sizeof(struct ip6_frag);
222
223 IP6Q_LOCK();
224
225 /*
226 * Enforce upper bound on number of fragments.
227 * If maxfrag is 0, never accept fragments.
228 * If maxfrag is -1, accept all fragments without limitation.
229 */
230 if (V_ip6_maxfrags < 0)
231 ;
232 else if (V_frag6_nfrags >= (u_int)V_ip6_maxfrags)
233 goto dropfrag;
234
235 for (q6 = V_ip6q.ip6q_next; q6 != &V_ip6q; q6 = q6->ip6q_next)
236 if (ip6f->ip6f_ident == q6->ip6q_ident &&
237 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
238 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst)
239 #ifdef MAC
240 && mac_ip6q_match(m, q6)
241 #endif
242 )
243 break;
244
245 if (q6 == &V_ip6q) {
246 /*
247 * the first fragment to arrive, create a reassembly queue.
248 */
249 first_frag = 1;
250
251 /*
252 * Enforce upper bound on number of fragmented packets
253 * for which we attempt reassembly;
254 * If maxfragpackets is 0, never accept fragments.
255 * If maxfragpackets is -1, accept all fragments without
256 * limitation.
257 */
258 if (V_ip6_maxfragpackets < 0)
259 ;
260 else if (V_frag6_nfragpackets >= (u_int)V_ip6_maxfragpackets)
261 goto dropfrag;
262 V_frag6_nfragpackets++;
263 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE,
264 M_NOWAIT);
265 if (q6 == NULL)
266 goto dropfrag;
267 bzero(q6, sizeof(*q6));
268 #ifdef MAC
269 if (mac_ip6q_init(q6, M_NOWAIT) != 0) {
270 free(q6, M_FTABLE);
271 goto dropfrag;
272 }
273 mac_ip6q_create(m, q6);
274 #endif
275 frag6_insque(q6, &V_ip6q);
276
277 /* ip6q_nxt will be filled afterwards, from 1st fragment */
278 q6->ip6q_down = q6->ip6q_up = (struct ip6asfrag *)q6;
279 #ifdef notyet
280 q6->ip6q_nxtp = (u_char *)nxtp;
281 #endif
282 q6->ip6q_ident = ip6f->ip6f_ident;
283 q6->ip6q_ttl = IPV6_FRAGTTL;
284 q6->ip6q_src = ip6->ip6_src;
285 q6->ip6q_dst = ip6->ip6_dst;
286 q6->ip6q_ecn =
287 (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
288 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
289
290 q6->ip6q_nfrag = 0;
291 }
292
293 /*
294 * If it's the 1st fragment, record the length of the
295 * unfragmentable part and the next header of the fragment header.
296 */
297 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
298 if (fragoff == 0) {
299 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) -
300 sizeof(struct ip6_frag);
301 q6->ip6q_nxt = ip6f->ip6f_nxt;
302 }
303
304 /*
305 * Check that the reassembled packet would not exceed 65535 bytes
306 * in size.
307 * If it would exceed, discard the fragment and return an ICMP error.
308 */
309 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
310 if (q6->ip6q_unfrglen >= 0) {
311 /* The 1st fragment has already arrived. */
312 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
313 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
314 offset - sizeof(struct ip6_frag) +
315 offsetof(struct ip6_frag, ip6f_offlg));
316 IP6Q_UNLOCK();
317 return (IPPROTO_DONE);
318 }
319 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
320 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
321 offset - sizeof(struct ip6_frag) +
322 offsetof(struct ip6_frag, ip6f_offlg));
323 IP6Q_UNLOCK();
324 return (IPPROTO_DONE);
325 }
326 /*
327 * If it's the first fragment, do the above check for each
328 * fragment already stored in the reassembly queue.
329 */
330 if (fragoff == 0) {
331 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
332 af6 = af6dwn) {
333 af6dwn = af6->ip6af_down;
334
335 if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen >
336 IPV6_MAXPACKET) {
337 struct mbuf *merr = IP6_REASS_MBUF(af6);
338 struct ip6_hdr *ip6err;
339 int erroff = af6->ip6af_offset;
340
341 /* dequeue the fragment. */
342 frag6_deq(af6);
343 free(af6, M_FTABLE);
344
345 /* adjust pointer. */
346 ip6err = mtod(merr, struct ip6_hdr *);
347
348 /*
349 * Restore source and destination addresses
350 * in the erroneous IPv6 header.
351 */
352 ip6err->ip6_src = q6->ip6q_src;
353 ip6err->ip6_dst = q6->ip6q_dst;
354
355 icmp6_error(merr, ICMP6_PARAM_PROB,
356 ICMP6_PARAMPROB_HEADER,
357 erroff - sizeof(struct ip6_frag) +
358 offsetof(struct ip6_frag, ip6f_offlg));
359 }
360 }
361 }
362
363 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FTABLE,
364 M_NOWAIT);
365 if (ip6af == NULL)
366 goto dropfrag;
367 bzero(ip6af, sizeof(*ip6af));
368 ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG;
369 ip6af->ip6af_off = fragoff;
370 ip6af->ip6af_frglen = frgpartlen;
371 ip6af->ip6af_offset = offset;
372 IP6_REASS_MBUF(ip6af) = m;
373
374 if (first_frag) {
375 af6 = (struct ip6asfrag *)q6;
376 goto insert;
377 }
378
379 /*
380 * Handle ECN by comparing this segment with the first one;
381 * if CE is set, do not lose CE.
382 * drop if CE and not-ECT are mixed for the same packet.
383 */
384 ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
385 ecn0 = q6->ip6q_ecn;
386 if (ecn == IPTOS_ECN_CE) {
387 if (ecn0 == IPTOS_ECN_NOTECT) {
388 free(ip6af, M_FTABLE);
389 goto dropfrag;
390 }
391 if (ecn0 != IPTOS_ECN_CE)
392 q6->ip6q_ecn = IPTOS_ECN_CE;
393 }
394 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) {
395 free(ip6af, M_FTABLE);
396 goto dropfrag;
397 }
398
399 /*
400 * Find a segment which begins after this one does.
401 */
402 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
403 af6 = af6->ip6af_down)
404 if (af6->ip6af_off > ip6af->ip6af_off)
405 break;
406
407 #if 0
408 /*
409 * If there is a preceding segment, it may provide some of
410 * our data already. If so, drop the data from the incoming
411 * segment. If it provides all of our data, drop us.
412 */
413 if (af6->ip6af_up != (struct ip6asfrag *)q6) {
414 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
415 - ip6af->ip6af_off;
416 if (i > 0) {
417 if (i >= ip6af->ip6af_frglen)
418 goto dropfrag;
419 m_adj(IP6_REASS_MBUF(ip6af), i);
420 ip6af->ip6af_off += i;
421 ip6af->ip6af_frglen -= i;
422 }
423 }
424
425 /*
426 * While we overlap succeeding segments trim them or,
427 * if they are completely covered, dequeue them.
428 */
429 while (af6 != (struct ip6asfrag *)q6 &&
430 ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) {
431 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
432 if (i < af6->ip6af_frglen) {
433 af6->ip6af_frglen -= i;
434 af6->ip6af_off += i;
435 m_adj(IP6_REASS_MBUF(af6), i);
436 break;
437 }
438 af6 = af6->ip6af_down;
439 m_freem(IP6_REASS_MBUF(af6->ip6af_up));
440 frag6_deq(af6->ip6af_up);
441 }
442 #else
443 /*
444 * If the incoming framgent overlaps some existing fragments in
445 * the reassembly queue, drop it, since it is dangerous to override
446 * existing fragments from a security point of view.
447 * We don't know which fragment is the bad guy - here we trust
448 * fragment that came in earlier, with no real reason.
449 *
450 * Note: due to changes after disabling this part, mbuf passed to
451 * m_adj() below now does not meet the requirement.
452 */
453 if (af6->ip6af_up != (struct ip6asfrag *)q6) {
454 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
455 - ip6af->ip6af_off;
456 if (i > 0) {
457 #if 0 /* suppress the noisy log */
458 log(LOG_ERR, "%d bytes of a fragment from %s "
459 "overlaps the previous fragment\n",
460 i, ip6_sprintf(ip6buf, &q6->ip6q_src));
461 #endif
462 free(ip6af, M_FTABLE);
463 goto dropfrag;
464 }
465 }
466 if (af6 != (struct ip6asfrag *)q6) {
467 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
468 if (i > 0) {
469 #if 0 /* suppress the noisy log */
470 log(LOG_ERR, "%d bytes of a fragment from %s "
471 "overlaps the succeeding fragment",
472 i, ip6_sprintf(ip6buf, &q6->ip6q_src));
473 #endif
474 free(ip6af, M_FTABLE);
475 goto dropfrag;
476 }
477 }
478 #endif
479
480 insert:
481 #ifdef MAC
482 if (!first_frag)
483 mac_ip6q_update(m, q6);
484 #endif
485
486 /*
487 * Stick new segment in its place;
488 * check for complete reassembly.
489 * Move to front of packet queue, as we are
490 * the most recently active fragmented packet.
491 */
492 frag6_enq(ip6af, af6->ip6af_up);
493 V_frag6_nfrags++;
494 q6->ip6q_nfrag++;
495 #if 0 /* xxx */
496 if (q6 != V_ip6q.ip6q_next) {
497 frag6_remque(q6);
498 frag6_insque(q6, &V_ip6q);
499 }
500 #endif
501 next = 0;
502 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
503 af6 = af6->ip6af_down) {
504 if (af6->ip6af_off != next) {
505 IP6Q_UNLOCK();
506 return IPPROTO_DONE;
507 }
508 next += af6->ip6af_frglen;
509 }
510 if (af6->ip6af_up->ip6af_mff) {
511 IP6Q_UNLOCK();
512 return IPPROTO_DONE;
513 }
514
515 /*
516 * Reassembly is complete; concatenate fragments.
517 */
518 ip6af = q6->ip6q_down;
519 t = m = IP6_REASS_MBUF(ip6af);
520 af6 = ip6af->ip6af_down;
521 frag6_deq(ip6af);
522 while (af6 != (struct ip6asfrag *)q6) {
523 af6dwn = af6->ip6af_down;
524 frag6_deq(af6);
525 while (t->m_next)
526 t = t->m_next;
527 t->m_next = IP6_REASS_MBUF(af6);
528 m_adj(t->m_next, af6->ip6af_offset);
529 free(af6, M_FTABLE);
530 af6 = af6dwn;
531 }
532
533 /* adjust offset to point where the original next header starts */
534 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
535 free(ip6af, M_FTABLE);
536 ip6 = mtod(m, struct ip6_hdr *);
537 ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr));
538 if (q6->ip6q_ecn == IPTOS_ECN_CE)
539 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20);
540 nxt = q6->ip6q_nxt;
541 #ifdef notyet
542 *q6->ip6q_nxtp = (u_char)(nxt & 0xff);
543 #endif
544
545 /* Delete frag6 header */
546 if (m->m_len >= offset + sizeof(struct ip6_frag)) {
547 /* This is the only possible case with !PULLDOWN_TEST */
548 ovbcopy((caddr_t)ip6, (caddr_t)ip6 + sizeof(struct ip6_frag),
549 offset);
550 m->m_data += sizeof(struct ip6_frag);
551 m->m_len -= sizeof(struct ip6_frag);
552 } else {
553 /* this comes with no copy if the boundary is on cluster */
554 if ((t = m_split(m, offset, M_DONTWAIT)) == NULL) {
555 frag6_remque(q6);
556 V_frag6_nfrags -= q6->ip6q_nfrag;
557 #ifdef MAC
558 mac_ip6q_destroy(q6);
559 #endif
560 free(q6, M_FTABLE);
561 V_frag6_nfragpackets--;
562 goto dropfrag;
563 }
564 m_adj(t, sizeof(struct ip6_frag));
565 m_cat(m, t);
566 }
567
568 /*
569 * Store NXT to the original.
570 */
571 {
572 char *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */
573 *prvnxtp = nxt;
574 }
575
576 frag6_remque(q6);
577 V_frag6_nfrags -= q6->ip6q_nfrag;
578 #ifdef MAC
579 mac_ip6q_reassemble(q6, m);
580 mac_ip6q_destroy(q6);
581 #endif
582 free(q6, M_FTABLE);
583 V_frag6_nfragpackets--;
584
585 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
586 int plen = 0;
587 for (t = m; t; t = t->m_next)
588 plen += t->m_len;
589 m->m_pkthdr.len = plen;
590 }
591
592 V_ip6stat.ip6s_reassembled++;
593 in6_ifstat_inc(dstifp, ifs6_reass_ok);
594
595 /*
596 * Tell launch routine the next header
597 */
598
599 *mp = m;
600 *offp = offset;
601
602 IP6Q_UNLOCK();
603 return nxt;
604
605 dropfrag:
606 IP6Q_UNLOCK();
607 in6_ifstat_inc(dstifp, ifs6_reass_fail);
608 V_ip6stat.ip6s_fragdropped++;
609 m_freem(m);
610 return IPPROTO_DONE;
611 }
612
613 /*
614 * Free a fragment reassembly header and all
615 * associated datagrams.
616 */
617 void
618 frag6_freef(struct ip6q *q6)
619 {
620 INIT_VNET_INET6(curvnet);
621 struct ip6asfrag *af6, *down6;
622
623 IP6Q_LOCK_ASSERT();
624
625 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
626 af6 = down6) {
627 struct mbuf *m = IP6_REASS_MBUF(af6);
628
629 down6 = af6->ip6af_down;
630 frag6_deq(af6);
631
632 /*
633 * Return ICMP time exceeded error for the 1st fragment.
634 * Just free other fragments.
635 */
636 if (af6->ip6af_off == 0) {
637 struct ip6_hdr *ip6;
638
639 /* adjust pointer */
640 ip6 = mtod(m, struct ip6_hdr *);
641
642 /* restore source and destination addresses */
643 ip6->ip6_src = q6->ip6q_src;
644 ip6->ip6_dst = q6->ip6q_dst;
645
646 icmp6_error(m, ICMP6_TIME_EXCEEDED,
647 ICMP6_TIME_EXCEED_REASSEMBLY, 0);
648 } else
649 m_freem(m);
650 free(af6, M_FTABLE);
651 }
652 frag6_remque(q6);
653 V_frag6_nfrags -= q6->ip6q_nfrag;
654 #ifdef MAC
655 mac_ip6q_destroy(q6);
656 #endif
657 free(q6, M_FTABLE);
658 V_frag6_nfragpackets--;
659 }
660
661 /*
662 * Put an ip fragment on a reassembly chain.
663 * Like insque, but pointers in middle of structure.
664 */
665 void
666 frag6_enq(struct ip6asfrag *af6, struct ip6asfrag *up6)
667 {
668
669 IP6Q_LOCK_ASSERT();
670
671 af6->ip6af_up = up6;
672 af6->ip6af_down = up6->ip6af_down;
673 up6->ip6af_down->ip6af_up = af6;
674 up6->ip6af_down = af6;
675 }
676
677 /*
678 * To frag6_enq as remque is to insque.
679 */
680 void
681 frag6_deq(struct ip6asfrag *af6)
682 {
683
684 IP6Q_LOCK_ASSERT();
685
686 af6->ip6af_up->ip6af_down = af6->ip6af_down;
687 af6->ip6af_down->ip6af_up = af6->ip6af_up;
688 }
689
690 void
691 frag6_insque(struct ip6q *new, struct ip6q *old)
692 {
693
694 IP6Q_LOCK_ASSERT();
695
696 new->ip6q_prev = old;
697 new->ip6q_next = old->ip6q_next;
698 old->ip6q_next->ip6q_prev= new;
699 old->ip6q_next = new;
700 }
701
702 void
703 frag6_remque(struct ip6q *p6)
704 {
705
706 IP6Q_LOCK_ASSERT();
707
708 p6->ip6q_prev->ip6q_next = p6->ip6q_next;
709 p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
710 }
711
712 /*
713 * IPv6 reassembling timer processing;
714 * if a timer expires on a reassembly
715 * queue, discard it.
716 */
717 void
718 frag6_slowtimo(void)
719 {
720 VNET_ITERATOR_DECL(vnet_iter);
721 struct ip6q *q6;
722
723 IP6Q_LOCK();
724 VNET_LIST_RLOCK();
725 VNET_FOREACH(vnet_iter) {
726 CURVNET_SET(vnet_iter);
727 INIT_VNET_INET6(vnet_iter);
728 q6 = V_ip6q.ip6q_next;
729 if (q6)
730 while (q6 != &V_ip6q) {
731 --q6->ip6q_ttl;
732 q6 = q6->ip6q_next;
733 if (q6->ip6q_prev->ip6q_ttl == 0) {
734 V_ip6stat.ip6s_fragtimeout++;
735 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
736 frag6_freef(q6->ip6q_prev);
737 }
738 }
739 /*
740 * If we are over the maximum number of fragments
741 * (due to the limit being lowered), drain off
742 * enough to get down to the new limit.
743 */
744 while (V_frag6_nfragpackets > (u_int)V_ip6_maxfragpackets &&
745 V_ip6q.ip6q_prev) {
746 V_ip6stat.ip6s_fragoverflow++;
747 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
748 frag6_freef(V_ip6q.ip6q_prev);
749 }
750 CURVNET_RESTORE();
751 }
752 VNET_LIST_RUNLOCK();
753 IP6Q_UNLOCK();
754
755 #if 0
756 /*
757 * Routing changes might produce a better route than we last used;
758 * make sure we notice eventually, even if forwarding only for one
759 * destination and the cache is never replaced.
760 */
761 if (V_ip6_forward_rt.ro_rt) {
762 RTFREE(V_ip6_forward_rt.ro_rt);
763 V_ip6_forward_rt.ro_rt = 0;
764 }
765 if (ipsrcchk_rt.ro_rt) {
766 RTFREE(ipsrcchk_rt.ro_rt);
767 ipsrcchk_rt.ro_rt = 0;
768 }
769 #endif
770 }
771
772 /*
773 * Drain off all datagram fragments.
774 */
775 void
776 frag6_drain(void)
777 {
778 VNET_ITERATOR_DECL(vnet_iter);
779
780 if (IP6Q_TRYLOCK() == 0)
781 return;
782 VNET_LIST_RLOCK();
783 VNET_FOREACH(vnet_iter) {
784 CURVNET_SET(vnet_iter);
785 INIT_VNET_INET6(vnet_iter);
786 while (V_ip6q.ip6q_next != &V_ip6q) {
787 V_ip6stat.ip6s_fragdropped++;
788 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
789 frag6_freef(V_ip6q.ip6q_next);
790 }
791 CURVNET_RESTORE();
792 }
793 VNET_LIST_RUNLOCK();
794 IP6Q_UNLOCK();
795 }
796
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