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("$FreeBSD$");
34
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/malloc.h>
38 #include <sys/mbuf.h>
39 #include <sys/domain.h>
40 #include <sys/protosw.h>
41 #include <sys/socket.h>
42 #include <sys/errno.h>
43 #include <sys/time.h>
44 #include <sys/kernel.h>
45 #include <sys/syslog.h>
46
47 #include <net/if.h>
48 #include <net/route.h>
49 #include <net/vnet.h>
50
51 #include <netinet/in.h>
52 #include <netinet/in_var.h>
53 #include <netinet/ip6.h>
54 #include <netinet6/ip6_var.h>
55 #include <netinet/icmp6.h>
56 #include <netinet/in_systm.h> /* for ECN definitions */
57 #include <netinet/ip.h> /* for ECN definitions */
58
59 #include <security/mac/mac_framework.h>
60
61 /*
62 * Define it to get a correct behavior on per-interface statistics.
63 * You will need to perform an extra routing table lookup, per fragment,
64 * to do it. This may, or may not be, a performance hit.
65 */
66 #define IN6_IFSTAT_STRICT
67
68 static void frag6_enq(struct ip6asfrag *, struct ip6asfrag *);
69 static void frag6_deq(struct ip6asfrag *);
70 static void frag6_insque(struct ip6q *, struct ip6q *);
71 static void frag6_remque(struct ip6q *);
72 static void frag6_freef(struct ip6q *);
73
74 static struct mtx ip6qlock;
75 /*
76 * These fields all protected by ip6qlock.
77 */
78 static VNET_DEFINE(u_int, frag6_nfragpackets);
79 static VNET_DEFINE(u_int, frag6_nfrags);
80 static VNET_DEFINE(struct ip6q, ip6q); /* ip6 reassemble queue */
81
82 #define V_frag6_nfragpackets VNET(frag6_nfragpackets)
83 #define V_frag6_nfrags VNET(frag6_nfrags)
84 #define V_ip6q VNET(ip6q)
85
86 #define IP6Q_LOCK_INIT() mtx_init(&ip6qlock, "ip6qlock", NULL, MTX_DEF);
87 #define IP6Q_LOCK() mtx_lock(&ip6qlock)
88 #define IP6Q_TRYLOCK() mtx_trylock(&ip6qlock)
89 #define IP6Q_LOCK_ASSERT() mtx_assert(&ip6qlock, MA_OWNED)
90 #define IP6Q_UNLOCK() mtx_unlock(&ip6qlock)
91
92 static MALLOC_DEFINE(M_FTABLE, "fragment", "fragment reassembly header");
93
94 /*
95 * Initialise reassembly queue and fragment identifier.
96 */
97 static void
98 frag6_change(void *tag)
99 {
100
101 V_ip6_maxfragpackets = nmbclusters / 4;
102 V_ip6_maxfrags = nmbclusters / 4;
103 }
104
105 void
106 frag6_init(void)
107 {
108
109 V_ip6_maxfragpackets = nmbclusters / 4;
110 V_ip6_maxfrags = nmbclusters / 4;
111 V_ip6q.ip6q_next = V_ip6q.ip6q_prev = &V_ip6q;
112
113 if (!IS_DEFAULT_VNET(curvnet))
114 return;
115
116 EVENTHANDLER_REGISTER(nmbclusters_change,
117 frag6_change, NULL, EVENTHANDLER_PRI_ANY);
118
119 IP6Q_LOCK_INIT();
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 struct mbuf *m = *mp, *t;
158 struct ip6_hdr *ip6;
159 struct ip6_frag *ip6f;
160 struct ip6q *q6;
161 struct ip6asfrag *af6, *ip6af, *af6dwn;
162 #ifdef IN6_IFSTAT_STRICT
163 struct in6_ifaddr *ia;
164 #endif
165 int offset = *offp, nxt, i, next;
166 int first_frag = 0;
167 int fragoff, frgpartlen; /* must be larger than u_int16_t */
168 struct ifnet *dstifp;
169 u_int8_t ecn, ecn0;
170 #if 0
171 char ip6buf[INET6_ADDRSTRLEN];
172 #endif
173
174 ip6 = mtod(m, struct ip6_hdr *);
175 #ifndef PULLDOWN_TEST
176 IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE);
177 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
178 #else
179 IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
180 if (ip6f == NULL)
181 return (IPPROTO_DONE);
182 #endif
183
184 dstifp = NULL;
185 #ifdef IN6_IFSTAT_STRICT
186 /* find the destination interface of the packet. */
187 if ((ia = ip6_getdstifaddr(m)) != NULL) {
188 dstifp = ia->ia_ifp;
189 ifa_free(&ia->ia_ifa);
190 }
191 #else
192 /* we are violating the spec, this is not the destination interface */
193 if ((m->m_flags & M_PKTHDR) != 0)
194 dstifp = m->m_pkthdr.rcvif;
195 #endif
196
197 /* jumbo payload can't contain a fragment header */
198 if (ip6->ip6_plen == 0) {
199 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
200 in6_ifstat_inc(dstifp, ifs6_reass_fail);
201 return IPPROTO_DONE;
202 }
203
204 /*
205 * check whether fragment packet's fragment length is
206 * multiple of 8 octets.
207 * sizeof(struct ip6_frag) == 8
208 * sizeof(struct ip6_hdr) = 40
209 */
210 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
211 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
212 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
213 offsetof(struct ip6_hdr, ip6_plen));
214 in6_ifstat_inc(dstifp, ifs6_reass_fail);
215 return IPPROTO_DONE;
216 }
217
218 IP6STAT_INC(ip6s_fragments);
219 in6_ifstat_inc(dstifp, ifs6_reass_reqd);
220
221 /* offset now points to data portion */
222 offset += sizeof(struct ip6_frag);
223
224 /*
225 * RFC 6946: Handle "atomic" fragments (offset and m bit set to 0)
226 * upfront, unrelated to any reassembly. Just skip the fragment header.
227 */
228 if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) {
229 /* XXX-BZ we want dedicated counters for this. */
230 IP6STAT_INC(ip6s_reassembled);
231 in6_ifstat_inc(dstifp, ifs6_reass_ok);
232 *offp = offset;
233 return (ip6f->ip6f_nxt);
234 }
235
236 IP6Q_LOCK();
237
238 /*
239 * Enforce upper bound on number of fragments.
240 * If maxfrag is 0, never accept fragments.
241 * If maxfrag is -1, accept all fragments without limitation.
242 */
243 if (V_ip6_maxfrags < 0)
244 ;
245 else if (V_frag6_nfrags >= (u_int)V_ip6_maxfrags)
246 goto dropfrag;
247
248 for (q6 = V_ip6q.ip6q_next; q6 != &V_ip6q; q6 = q6->ip6q_next)
249 if (ip6f->ip6f_ident == q6->ip6q_ident &&
250 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
251 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst)
252 #ifdef MAC
253 && mac_ip6q_match(m, q6)
254 #endif
255 )
256 break;
257
258 if (q6 == &V_ip6q) {
259 /*
260 * the first fragment to arrive, create a reassembly queue.
261 */
262 first_frag = 1;
263
264 /*
265 * Enforce upper bound on number of fragmented packets
266 * for which we attempt reassembly;
267 * If maxfragpackets is 0, never accept fragments.
268 * If maxfragpackets is -1, accept all fragments without
269 * limitation.
270 */
271 if (V_ip6_maxfragpackets < 0)
272 ;
273 else if (V_frag6_nfragpackets >= (u_int)V_ip6_maxfragpackets)
274 goto dropfrag;
275 V_frag6_nfragpackets++;
276 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE,
277 M_NOWAIT);
278 if (q6 == NULL)
279 goto dropfrag;
280 bzero(q6, sizeof(*q6));
281 #ifdef MAC
282 if (mac_ip6q_init(q6, M_NOWAIT) != 0) {
283 free(q6, M_FTABLE);
284 goto dropfrag;
285 }
286 mac_ip6q_create(m, q6);
287 #endif
288 frag6_insque(q6, &V_ip6q);
289
290 /* ip6q_nxt will be filled afterwards, from 1st fragment */
291 q6->ip6q_down = q6->ip6q_up = (struct ip6asfrag *)q6;
292 #ifdef notyet
293 q6->ip6q_nxtp = (u_char *)nxtp;
294 #endif
295 q6->ip6q_ident = ip6f->ip6f_ident;
296 q6->ip6q_ttl = IPV6_FRAGTTL;
297 q6->ip6q_src = ip6->ip6_src;
298 q6->ip6q_dst = ip6->ip6_dst;
299 q6->ip6q_ecn =
300 (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
301 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
302
303 q6->ip6q_nfrag = 0;
304 }
305
306 /*
307 * If it's the 1st fragment, record the length of the
308 * unfragmentable part and the next header of the fragment header.
309 */
310 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
311 if (fragoff == 0) {
312 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) -
313 sizeof(struct ip6_frag);
314 q6->ip6q_nxt = ip6f->ip6f_nxt;
315 }
316
317 /*
318 * Check that the reassembled packet would not exceed 65535 bytes
319 * in size.
320 * If it would exceed, discard the fragment and return an ICMP error.
321 */
322 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
323 if (q6->ip6q_unfrglen >= 0) {
324 /* The 1st fragment has already arrived. */
325 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
326 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
327 offset - sizeof(struct ip6_frag) +
328 offsetof(struct ip6_frag, ip6f_offlg));
329 IP6Q_UNLOCK();
330 return (IPPROTO_DONE);
331 }
332 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
333 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
334 offset - sizeof(struct ip6_frag) +
335 offsetof(struct ip6_frag, ip6f_offlg));
336 IP6Q_UNLOCK();
337 return (IPPROTO_DONE);
338 }
339 /*
340 * If it's the first fragment, do the above check for each
341 * fragment already stored in the reassembly queue.
342 */
343 if (fragoff == 0) {
344 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
345 af6 = af6dwn) {
346 af6dwn = af6->ip6af_down;
347
348 if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen >
349 IPV6_MAXPACKET) {
350 struct mbuf *merr = IP6_REASS_MBUF(af6);
351 struct ip6_hdr *ip6err;
352 int erroff = af6->ip6af_offset;
353
354 /* dequeue the fragment. */
355 frag6_deq(af6);
356 free(af6, M_FTABLE);
357
358 /* adjust pointer. */
359 ip6err = mtod(merr, struct ip6_hdr *);
360
361 /*
362 * Restore source and destination addresses
363 * in the erroneous IPv6 header.
364 */
365 ip6err->ip6_src = q6->ip6q_src;
366 ip6err->ip6_dst = q6->ip6q_dst;
367
368 icmp6_error(merr, ICMP6_PARAM_PROB,
369 ICMP6_PARAMPROB_HEADER,
370 erroff - sizeof(struct ip6_frag) +
371 offsetof(struct ip6_frag, ip6f_offlg));
372 }
373 }
374 }
375
376 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FTABLE,
377 M_NOWAIT);
378 if (ip6af == NULL)
379 goto dropfrag;
380 bzero(ip6af, sizeof(*ip6af));
381 ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG;
382 ip6af->ip6af_off = fragoff;
383 ip6af->ip6af_frglen = frgpartlen;
384 ip6af->ip6af_offset = offset;
385 IP6_REASS_MBUF(ip6af) = m;
386
387 if (first_frag) {
388 af6 = (struct ip6asfrag *)q6;
389 goto insert;
390 }
391
392 /*
393 * Handle ECN by comparing this segment with the first one;
394 * if CE is set, do not lose CE.
395 * drop if CE and not-ECT are mixed for the same packet.
396 */
397 ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
398 ecn0 = q6->ip6q_ecn;
399 if (ecn == IPTOS_ECN_CE) {
400 if (ecn0 == IPTOS_ECN_NOTECT) {
401 free(ip6af, M_FTABLE);
402 goto dropfrag;
403 }
404 if (ecn0 != IPTOS_ECN_CE)
405 q6->ip6q_ecn = IPTOS_ECN_CE;
406 }
407 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) {
408 free(ip6af, M_FTABLE);
409 goto dropfrag;
410 }
411
412 /*
413 * Find a segment which begins after this one does.
414 */
415 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
416 af6 = af6->ip6af_down)
417 if (af6->ip6af_off > ip6af->ip6af_off)
418 break;
419
420 #if 0
421 /*
422 * If there is a preceding segment, it may provide some of
423 * our data already. If so, drop the data from the incoming
424 * segment. If it provides all of our data, drop us.
425 */
426 if (af6->ip6af_up != (struct ip6asfrag *)q6) {
427 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
428 - ip6af->ip6af_off;
429 if (i > 0) {
430 if (i >= ip6af->ip6af_frglen)
431 goto dropfrag;
432 m_adj(IP6_REASS_MBUF(ip6af), i);
433 ip6af->ip6af_off += i;
434 ip6af->ip6af_frglen -= i;
435 }
436 }
437
438 /*
439 * While we overlap succeeding segments trim them or,
440 * if they are completely covered, dequeue them.
441 */
442 while (af6 != (struct ip6asfrag *)q6 &&
443 ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) {
444 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
445 if (i < af6->ip6af_frglen) {
446 af6->ip6af_frglen -= i;
447 af6->ip6af_off += i;
448 m_adj(IP6_REASS_MBUF(af6), i);
449 break;
450 }
451 af6 = af6->ip6af_down;
452 m_freem(IP6_REASS_MBUF(af6->ip6af_up));
453 frag6_deq(af6->ip6af_up);
454 }
455 #else
456 /*
457 * If the incoming framgent overlaps some existing fragments in
458 * the reassembly queue, drop it, since it is dangerous to override
459 * existing fragments from a security point of view.
460 * We don't know which fragment is the bad guy - here we trust
461 * fragment that came in earlier, with no real reason.
462 *
463 * Note: due to changes after disabling this part, mbuf passed to
464 * m_adj() below now does not meet the requirement.
465 */
466 if (af6->ip6af_up != (struct ip6asfrag *)q6) {
467 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
468 - ip6af->ip6af_off;
469 if (i > 0) {
470 #if 0 /* suppress the noisy log */
471 log(LOG_ERR, "%d bytes of a fragment from %s "
472 "overlaps the previous fragment\n",
473 i, ip6_sprintf(ip6buf, &q6->ip6q_src));
474 #endif
475 free(ip6af, M_FTABLE);
476 goto dropfrag;
477 }
478 }
479 if (af6 != (struct ip6asfrag *)q6) {
480 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
481 if (i > 0) {
482 #if 0 /* suppress the noisy log */
483 log(LOG_ERR, "%d bytes of a fragment from %s "
484 "overlaps the succeeding fragment",
485 i, ip6_sprintf(ip6buf, &q6->ip6q_src));
486 #endif
487 free(ip6af, M_FTABLE);
488 goto dropfrag;
489 }
490 }
491 #endif
492
493 insert:
494 #ifdef MAC
495 if (!first_frag)
496 mac_ip6q_update(m, q6);
497 #endif
498
499 /*
500 * Stick new segment in its place;
501 * check for complete reassembly.
502 * Move to front of packet queue, as we are
503 * the most recently active fragmented packet.
504 */
505 frag6_enq(ip6af, af6->ip6af_up);
506 V_frag6_nfrags++;
507 q6->ip6q_nfrag++;
508 #if 0 /* xxx */
509 if (q6 != V_ip6q.ip6q_next) {
510 frag6_remque(q6);
511 frag6_insque(q6, &V_ip6q);
512 }
513 #endif
514 next = 0;
515 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
516 af6 = af6->ip6af_down) {
517 if (af6->ip6af_off != next) {
518 IP6Q_UNLOCK();
519 return IPPROTO_DONE;
520 }
521 next += af6->ip6af_frglen;
522 }
523 if (af6->ip6af_up->ip6af_mff) {
524 IP6Q_UNLOCK();
525 return IPPROTO_DONE;
526 }
527
528 /*
529 * Reassembly is complete; concatenate fragments.
530 */
531 ip6af = q6->ip6q_down;
532 t = m = IP6_REASS_MBUF(ip6af);
533 af6 = ip6af->ip6af_down;
534 frag6_deq(ip6af);
535 while (af6 != (struct ip6asfrag *)q6) {
536 af6dwn = af6->ip6af_down;
537 frag6_deq(af6);
538 while (t->m_next)
539 t = t->m_next;
540 t->m_next = IP6_REASS_MBUF(af6);
541 m_adj(t->m_next, af6->ip6af_offset);
542 free(af6, M_FTABLE);
543 af6 = af6dwn;
544 }
545
546 /* adjust offset to point where the original next header starts */
547 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
548 free(ip6af, M_FTABLE);
549 ip6 = mtod(m, struct ip6_hdr *);
550 ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr));
551 if (q6->ip6q_ecn == IPTOS_ECN_CE)
552 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20);
553 nxt = q6->ip6q_nxt;
554 #ifdef notyet
555 *q6->ip6q_nxtp = (u_char)(nxt & 0xff);
556 #endif
557
558 /* Delete frag6 header */
559 if (m->m_len >= offset + sizeof(struct ip6_frag)) {
560 /* This is the only possible case with !PULLDOWN_TEST */
561 ovbcopy((caddr_t)ip6, (caddr_t)ip6 + sizeof(struct ip6_frag),
562 offset);
563 m->m_data += sizeof(struct ip6_frag);
564 m->m_len -= sizeof(struct ip6_frag);
565 } else {
566 /* this comes with no copy if the boundary is on cluster */
567 if ((t = m_split(m, offset, M_DONTWAIT)) == NULL) {
568 frag6_remque(q6);
569 V_frag6_nfrags -= q6->ip6q_nfrag;
570 #ifdef MAC
571 mac_ip6q_destroy(q6);
572 #endif
573 free(q6, M_FTABLE);
574 V_frag6_nfragpackets--;
575 goto dropfrag;
576 }
577 m_adj(t, sizeof(struct ip6_frag));
578 m_cat(m, t);
579 }
580
581 /*
582 * Store NXT to the original.
583 */
584 {
585 char *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */
586 *prvnxtp = nxt;
587 }
588
589 frag6_remque(q6);
590 V_frag6_nfrags -= q6->ip6q_nfrag;
591 #ifdef MAC
592 mac_ip6q_reassemble(q6, m);
593 mac_ip6q_destroy(q6);
594 #endif
595 free(q6, M_FTABLE);
596 V_frag6_nfragpackets--;
597
598 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
599 int plen = 0;
600 for (t = m; t; t = t->m_next)
601 plen += t->m_len;
602 m->m_pkthdr.len = plen;
603 }
604
605 IP6STAT_INC(ip6s_reassembled);
606 in6_ifstat_inc(dstifp, ifs6_reass_ok);
607
608 /*
609 * Tell launch routine the next header
610 */
611
612 *mp = m;
613 *offp = offset;
614
615 IP6Q_UNLOCK();
616 return nxt;
617
618 dropfrag:
619 IP6Q_UNLOCK();
620 in6_ifstat_inc(dstifp, ifs6_reass_fail);
621 IP6STAT_INC(ip6s_fragdropped);
622 m_freem(m);
623 return IPPROTO_DONE;
624 }
625
626 /*
627 * Free a fragment reassembly header and all
628 * associated datagrams.
629 */
630 void
631 frag6_freef(struct ip6q *q6)
632 {
633 struct ip6asfrag *af6, *down6;
634
635 IP6Q_LOCK_ASSERT();
636
637 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
638 af6 = down6) {
639 struct mbuf *m = IP6_REASS_MBUF(af6);
640
641 down6 = af6->ip6af_down;
642 frag6_deq(af6);
643
644 /*
645 * Return ICMP time exceeded error for the 1st fragment.
646 * Just free other fragments.
647 */
648 if (af6->ip6af_off == 0) {
649 struct ip6_hdr *ip6;
650
651 /* adjust pointer */
652 ip6 = mtod(m, struct ip6_hdr *);
653
654 /* restore source and destination addresses */
655 ip6->ip6_src = q6->ip6q_src;
656 ip6->ip6_dst = q6->ip6q_dst;
657
658 icmp6_error(m, ICMP6_TIME_EXCEEDED,
659 ICMP6_TIME_EXCEED_REASSEMBLY, 0);
660 } else
661 m_freem(m);
662 free(af6, M_FTABLE);
663 }
664 frag6_remque(q6);
665 V_frag6_nfrags -= q6->ip6q_nfrag;
666 #ifdef MAC
667 mac_ip6q_destroy(q6);
668 #endif
669 free(q6, M_FTABLE);
670 V_frag6_nfragpackets--;
671 }
672
673 /*
674 * Put an ip fragment on a reassembly chain.
675 * Like insque, but pointers in middle of structure.
676 */
677 void
678 frag6_enq(struct ip6asfrag *af6, struct ip6asfrag *up6)
679 {
680
681 IP6Q_LOCK_ASSERT();
682
683 af6->ip6af_up = up6;
684 af6->ip6af_down = up6->ip6af_down;
685 up6->ip6af_down->ip6af_up = af6;
686 up6->ip6af_down = af6;
687 }
688
689 /*
690 * To frag6_enq as remque is to insque.
691 */
692 void
693 frag6_deq(struct ip6asfrag *af6)
694 {
695
696 IP6Q_LOCK_ASSERT();
697
698 af6->ip6af_up->ip6af_down = af6->ip6af_down;
699 af6->ip6af_down->ip6af_up = af6->ip6af_up;
700 }
701
702 void
703 frag6_insque(struct ip6q *new, struct ip6q *old)
704 {
705
706 IP6Q_LOCK_ASSERT();
707
708 new->ip6q_prev = old;
709 new->ip6q_next = old->ip6q_next;
710 old->ip6q_next->ip6q_prev= new;
711 old->ip6q_next = new;
712 }
713
714 void
715 frag6_remque(struct ip6q *p6)
716 {
717
718 IP6Q_LOCK_ASSERT();
719
720 p6->ip6q_prev->ip6q_next = p6->ip6q_next;
721 p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
722 }
723
724 /*
725 * IPv6 reassembling timer processing;
726 * if a timer expires on a reassembly
727 * queue, discard it.
728 */
729 void
730 frag6_slowtimo(void)
731 {
732 VNET_ITERATOR_DECL(vnet_iter);
733 struct ip6q *q6;
734
735 VNET_LIST_RLOCK_NOSLEEP();
736 IP6Q_LOCK();
737 VNET_FOREACH(vnet_iter) {
738 CURVNET_SET(vnet_iter);
739 q6 = V_ip6q.ip6q_next;
740 if (q6)
741 while (q6 != &V_ip6q) {
742 --q6->ip6q_ttl;
743 q6 = q6->ip6q_next;
744 if (q6->ip6q_prev->ip6q_ttl == 0) {
745 IP6STAT_INC(ip6s_fragtimeout);
746 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
747 frag6_freef(q6->ip6q_prev);
748 }
749 }
750 /*
751 * If we are over the maximum number of fragments
752 * (due to the limit being lowered), drain off
753 * enough to get down to the new limit.
754 */
755 while (V_frag6_nfragpackets > (u_int)V_ip6_maxfragpackets &&
756 V_ip6q.ip6q_prev) {
757 IP6STAT_INC(ip6s_fragoverflow);
758 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
759 frag6_freef(V_ip6q.ip6q_prev);
760 }
761 CURVNET_RESTORE();
762 }
763 IP6Q_UNLOCK();
764 VNET_LIST_RUNLOCK_NOSLEEP();
765 }
766
767 /*
768 * Drain off all datagram fragments.
769 */
770 void
771 frag6_drain(void)
772 {
773 VNET_ITERATOR_DECL(vnet_iter);
774
775 VNET_LIST_RLOCK_NOSLEEP();
776 if (IP6Q_TRYLOCK() == 0) {
777 VNET_LIST_RUNLOCK_NOSLEEP();
778 return;
779 }
780 VNET_FOREACH(vnet_iter) {
781 CURVNET_SET(vnet_iter);
782 while (V_ip6q.ip6q_next != &V_ip6q) {
783 IP6STAT_INC(ip6s_fragdropped);
784 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
785 frag6_freef(V_ip6q.ip6q_next);
786 }
787 CURVNET_RESTORE();
788 }
789 IP6Q_UNLOCK();
790 VNET_LIST_RUNLOCK_NOSLEEP();
791 }
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