1 /* $FreeBSD: src/sys/netinet6/frag6.c,v 1.2.2.6 2002/04/28 05:40:26 suz Exp $ */
2 /* $DragonFly: src/sys/netinet6/frag6.c,v 1.2 2003/06/17 04:28:51 dillon Exp $ */
3 /* $KAME: frag6.c,v 1.33 2002/01/07 11:34:48 kjc Exp $ */
6 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the project nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/malloc.h>
38 #include <sys/domain.h>
39 #include <sys/protosw.h>
40 #include <sys/socket.h>
41 #include <sys/errno.h>
43 #include <sys/kernel.h>
44 #include <sys/syslog.h>
47 #include <net/route.h>
49 #include <netinet/in.h>
50 #include <netinet/in_var.h>
51 #include <netinet/ip6.h>
52 #include <netinet6/ip6_var.h>
53 #include <netinet/icmp6.h>
55 #include <net/net_osdep.h>
58 * Define it to get a correct behavior on per-interface statistics.
59 * You will need to perform an extra routing table lookup, per fragment,
60 * to do it. This may, or may not be, a performance hit.
62 #define IN6_IFSTAT_STRICT
64 static void frag6_enq __P((struct ip6asfrag *, struct ip6asfrag *));
65 static void frag6_deq __P((struct ip6asfrag *));
66 static void frag6_insque __P((struct ip6q *, struct ip6q *));
67 static void frag6_remque __P((struct ip6q *));
68 static void frag6_freef __P((struct ip6q *));
70 /* XXX we eventually need splreass6, or some real semaphore */
71 int frag6_doing_reass;
72 u_int frag6_nfragpackets;
73 struct ip6q ip6q; /* ip6 reassemble queue */
76 MALLOC_DEFINE(M_FTABLE, "fragment", "fragment reassembly header");
79 * Initialise reassembly queue and fragment identifier.
86 ip6_maxfragpackets = nmbclusters / 4;
89 * in many cases, random() here does NOT return random number
90 * as initialization during bootstrap time occur in fixed order.
93 ip6_id = random() ^ tv.tv_usec;
94 ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q;
98 * In RFC2460, fragment and reassembly rule do not agree with each other,
99 * in terms of next header field handling in fragment header.
100 * While the sender will use the same value for all of the fragmented packets,
101 * receiver is suggested not to check the consistency.
103 * fragment rule (p20):
104 * (2) A Fragment header containing:
105 * The Next Header value that identifies the first header of
106 * the Fragmentable Part of the original packet.
107 * -> next header field is same for all fragments
109 * reassembly rule (p21):
110 * The Next Header field of the last header of the Unfragmentable
111 * Part is obtained from the Next Header field of the first
112 * fragment's Fragment header.
113 * -> should grab it from the first fragment only
115 * The following note also contradicts with fragment rule - noone is going to
116 * send different fragment with different next header field.
118 * additional note (p22):
119 * The Next Header values in the Fragment headers of different
120 * fragments of the same original packet may differ. Only the value
121 * from the Offset zero fragment packet is used for reassembly.
122 * -> should grab it from the first fragment only
124 * There is no explicit reason given in the RFC. Historical reason maybe?
130 frag6_input(mp, offp, proto)
134 struct mbuf *m = *mp, *t;
136 struct ip6_frag *ip6f;
138 struct ip6asfrag *af6, *ip6af, *af6dwn;
139 int offset = *offp, nxt, i, next;
141 int fragoff, frgpartlen; /* must be larger than u_int16_t */
142 struct ifnet *dstifp;
143 #ifdef IN6_IFSTAT_STRICT
144 static struct route_in6 ro;
145 struct sockaddr_in6 *dst;
148 ip6 = mtod(m, struct ip6_hdr *);
149 #ifndef PULLDOWN_TEST
150 IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE);
151 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
153 IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
159 #ifdef IN6_IFSTAT_STRICT
160 /* find the destination interface of the packet. */
161 dst = (struct sockaddr_in6 *)&ro.ro_dst;
163 && ((ro.ro_rt->rt_flags & RTF_UP) == 0
164 || !IN6_ARE_ADDR_EQUAL(&dst->sin6_addr, &ip6->ip6_dst))) {
166 ro.ro_rt = (struct rtentry *)0;
168 if (ro.ro_rt == NULL) {
169 bzero(dst, sizeof(*dst));
170 dst->sin6_family = AF_INET6;
171 dst->sin6_len = sizeof(struct sockaddr_in6);
172 dst->sin6_addr = ip6->ip6_dst;
174 rtalloc((struct route *)&ro);
175 if (ro.ro_rt != NULL && ro.ro_rt->rt_ifa != NULL)
176 dstifp = ((struct in6_ifaddr *)ro.ro_rt->rt_ifa)->ia_ifp;
178 /* we are violating the spec, this is not the destination interface */
179 if ((m->m_flags & M_PKTHDR) != 0)
180 dstifp = m->m_pkthdr.rcvif;
183 /* jumbo payload can't contain a fragment header */
184 if (ip6->ip6_plen == 0) {
185 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
186 in6_ifstat_inc(dstifp, ifs6_reass_fail);
191 * check whether fragment packet's fragment length is
192 * multiple of 8 octets.
193 * sizeof(struct ip6_frag) == 8
194 * sizeof(struct ip6_hdr) = 40
196 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
197 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
198 icmp6_error(m, ICMP6_PARAM_PROB,
199 ICMP6_PARAMPROB_HEADER,
200 offsetof(struct ip6_hdr, ip6_plen));
201 in6_ifstat_inc(dstifp, ifs6_reass_fail);
205 ip6stat.ip6s_fragments++;
206 in6_ifstat_inc(dstifp, ifs6_reass_reqd);
208 /* offset now points to data portion */
209 offset += sizeof(struct ip6_frag);
211 frag6_doing_reass = 1;
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))
221 * the first fragment to arrive, create a reassembly queue.
226 * Enforce upper bound on number of fragmented packets
227 * for which we attempt reassembly;
228 * If maxfrag is 0, never accept fragments.
229 * If maxfrag is -1, accept all fragments without limitation.
231 if (ip6_maxfragpackets < 0)
233 else if (frag6_nfragpackets >= (u_int)ip6_maxfragpackets)
235 frag6_nfragpackets++;
236 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE,
240 bzero(q6, sizeof(*q6));
242 frag6_insque(q6, &ip6q);
244 /* ip6q_nxt will be filled afterwards, from 1st fragment */
245 q6->ip6q_down = q6->ip6q_up = (struct ip6asfrag *)q6;
247 q6->ip6q_nxtp = (u_char *)nxtp;
249 q6->ip6q_ident = ip6f->ip6f_ident;
250 q6->ip6q_arrive = 0; /* Is it used anywhere? */
251 q6->ip6q_ttl = IPV6_FRAGTTL;
252 q6->ip6q_src = ip6->ip6_src;
253 q6->ip6q_dst = ip6->ip6_dst;
254 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
258 * If it's the 1st fragment, record the length of the
259 * unfragmentable part and the next header of the fragment header.
261 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
263 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr)
264 - sizeof(struct ip6_frag);
265 q6->ip6q_nxt = ip6f->ip6f_nxt;
269 * Check that the reassembled packet would not exceed 65535 bytes
271 * If it would exceed, discard the fragment and return an ICMP error.
273 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
274 if (q6->ip6q_unfrglen >= 0) {
275 /* The 1st fragment has already arrived. */
276 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
277 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
278 offset - sizeof(struct ip6_frag) +
279 offsetof(struct ip6_frag, ip6f_offlg));
280 frag6_doing_reass = 0;
281 return(IPPROTO_DONE);
284 else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
285 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
286 offset - sizeof(struct ip6_frag) +
287 offsetof(struct ip6_frag, ip6f_offlg));
288 frag6_doing_reass = 0;
289 return(IPPROTO_DONE);
292 * If it's the first fragment, do the above check for each
293 * fragment already stored in the reassembly queue.
296 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
298 af6dwn = af6->ip6af_down;
300 if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen >
302 struct mbuf *merr = IP6_REASS_MBUF(af6);
303 struct ip6_hdr *ip6err;
304 int erroff = af6->ip6af_offset;
306 /* dequeue the fragment. */
310 /* adjust pointer. */
311 ip6err = mtod(merr, struct ip6_hdr *);
314 * Restore source and destination addresses
315 * in the erroneous IPv6 header.
317 ip6err->ip6_src = q6->ip6q_src;
318 ip6err->ip6_dst = q6->ip6q_dst;
320 icmp6_error(merr, ICMP6_PARAM_PROB,
321 ICMP6_PARAMPROB_HEADER,
322 erroff - sizeof(struct ip6_frag) +
323 offsetof(struct ip6_frag, ip6f_offlg));
328 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FTABLE,
332 bzero(ip6af, sizeof(*ip6af));
333 ip6af->ip6af_head = ip6->ip6_flow;
334 ip6af->ip6af_len = ip6->ip6_plen;
335 ip6af->ip6af_nxt = ip6->ip6_nxt;
336 ip6af->ip6af_hlim = ip6->ip6_hlim;
337 ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG;
338 ip6af->ip6af_off = fragoff;
339 ip6af->ip6af_frglen = frgpartlen;
340 ip6af->ip6af_offset = offset;
341 IP6_REASS_MBUF(ip6af) = m;
344 af6 = (struct ip6asfrag *)q6;
349 * Find a segment which begins after this one does.
351 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
352 af6 = af6->ip6af_down)
353 if (af6->ip6af_off > ip6af->ip6af_off)
358 * If there is a preceding segment, it may provide some of
359 * our data already. If so, drop the data from the incoming
360 * segment. If it provides all of our data, drop us.
362 if (af6->ip6af_up != (struct ip6asfrag *)q6) {
363 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
366 if (i >= ip6af->ip6af_frglen)
368 m_adj(IP6_REASS_MBUF(ip6af), i);
369 ip6af->ip6af_off += i;
370 ip6af->ip6af_frglen -= i;
375 * While we overlap succeeding segments trim them or,
376 * if they are completely covered, dequeue them.
378 while (af6 != (struct ip6asfrag *)q6 &&
379 ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) {
380 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
381 if (i < af6->ip6af_frglen) {
382 af6->ip6af_frglen -= i;
384 m_adj(IP6_REASS_MBUF(af6), i);
387 af6 = af6->ip6af_down;
388 m_freem(IP6_REASS_MBUF(af6->ip6af_up));
389 frag6_deq(af6->ip6af_up);
393 * If the incoming framgent overlaps some existing fragments in
394 * the reassembly queue, drop it, since it is dangerous to override
395 * existing fragments from a security point of view.
397 if (af6->ip6af_up != (struct ip6asfrag *)q6) {
398 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
401 #if 0 /* suppress the noisy log */
402 log(LOG_ERR, "%d bytes of a fragment from %s "
403 "overlaps the previous fragment\n",
404 i, ip6_sprintf(&q6->ip6q_src));
406 free(ip6af, M_FTABLE);
410 if (af6 != (struct ip6asfrag *)q6) {
411 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
413 #if 0 /* suppress the noisy log */
414 log(LOG_ERR, "%d bytes of a fragment from %s "
415 "overlaps the succeeding fragment",
416 i, ip6_sprintf(&q6->ip6q_src));
418 free(ip6af, M_FTABLE);
427 * Stick new segment in its place;
428 * check for complete reassembly.
429 * Move to front of packet queue, as we are
430 * the most recently active fragmented packet.
432 frag6_enq(ip6af, af6->ip6af_up);
434 if (q6 != ip6q.ip6q_next) {
436 frag6_insque(q6, &ip6q);
440 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
441 af6 = af6->ip6af_down) {
442 if (af6->ip6af_off != next) {
443 frag6_doing_reass = 0;
446 next += af6->ip6af_frglen;
448 if (af6->ip6af_up->ip6af_mff) {
449 frag6_doing_reass = 0;
454 * Reassembly is complete; concatenate fragments.
456 ip6af = q6->ip6q_down;
457 t = m = IP6_REASS_MBUF(ip6af);
458 af6 = ip6af->ip6af_down;
460 while (af6 != (struct ip6asfrag *)q6) {
461 af6dwn = af6->ip6af_down;
465 t->m_next = IP6_REASS_MBUF(af6);
466 m_adj(t->m_next, af6->ip6af_offset);
471 /* adjust offset to point where the original next header starts */
472 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
473 free(ip6af, M_FTABLE);
474 ip6 = mtod(m, struct ip6_hdr *);
475 ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr));
476 ip6->ip6_src = q6->ip6q_src;
477 ip6->ip6_dst = q6->ip6q_dst;
480 *q6->ip6q_nxtp = (u_char)(nxt & 0xff);
484 * Delete frag6 header with as a few cost as possible.
486 if (offset < m->m_len) {
487 ovbcopy((caddr_t)ip6, (caddr_t)ip6 + sizeof(struct ip6_frag),
489 m->m_data += sizeof(struct ip6_frag);
490 m->m_len -= sizeof(struct ip6_frag);
492 /* this comes with no copy if the boundary is on cluster */
493 if ((t = m_split(m, offset, M_DONTWAIT)) == NULL) {
496 frag6_nfragpackets--;
499 m_adj(t, sizeof(struct ip6_frag));
504 * Store NXT to the original.
507 char *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */
513 frag6_nfragpackets--;
515 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
517 for (t = m; t; t = t->m_next)
519 m->m_pkthdr.len = plen;
522 ip6stat.ip6s_reassembled++;
523 in6_ifstat_inc(dstifp, ifs6_reass_ok);
526 * Tell launch routine the next header
532 frag6_doing_reass = 0;
536 in6_ifstat_inc(dstifp, ifs6_reass_fail);
537 ip6stat.ip6s_fragdropped++;
539 frag6_doing_reass = 0;
544 * Free a fragment reassembly header and all
545 * associated datagrams.
551 struct ip6asfrag *af6, *down6;
553 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
555 struct mbuf *m = IP6_REASS_MBUF(af6);
557 down6 = af6->ip6af_down;
561 * Return ICMP time exceeded error for the 1st fragment.
562 * Just free other fragments.
564 if (af6->ip6af_off == 0) {
568 ip6 = mtod(m, struct ip6_hdr *);
570 /* restoure source and destination addresses */
571 ip6->ip6_src = q6->ip6q_src;
572 ip6->ip6_dst = q6->ip6q_dst;
574 icmp6_error(m, ICMP6_TIME_EXCEEDED,
575 ICMP6_TIME_EXCEED_REASSEMBLY, 0);
582 frag6_nfragpackets--;
586 * Put an ip fragment on a reassembly chain.
587 * Like insque, but pointers in middle of structure.
591 struct ip6asfrag *af6, *up6;
594 af6->ip6af_down = up6->ip6af_down;
595 up6->ip6af_down->ip6af_up = af6;
596 up6->ip6af_down = af6;
600 * To frag6_enq as remque is to insque.
604 struct ip6asfrag *af6;
606 af6->ip6af_up->ip6af_down = af6->ip6af_down;
607 af6->ip6af_down->ip6af_up = af6->ip6af_up;
611 frag6_insque(new, old)
612 struct ip6q *new, *old;
614 new->ip6q_prev = old;
615 new->ip6q_next = old->ip6q_next;
616 old->ip6q_next->ip6q_prev= new;
617 old->ip6q_next = new;
624 p6->ip6q_prev->ip6q_next = p6->ip6q_next;
625 p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
629 * IPv6 reassembling timer processing;
630 * if a timer expires on a reassembly
639 frag6_doing_reass = 1;
642 while (q6 != &ip6q) {
645 if (q6->ip6q_prev->ip6q_ttl == 0) {
646 ip6stat.ip6s_fragtimeout++;
647 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
648 frag6_freef(q6->ip6q_prev);
652 * If we are over the maximum number of fragments
653 * (due to the limit being lowered), drain off
654 * enough to get down to the new limit.
656 while (frag6_nfragpackets > (u_int)ip6_maxfragpackets &&
658 ip6stat.ip6s_fragoverflow++;
659 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
660 frag6_freef(ip6q.ip6q_prev);
662 frag6_doing_reass = 0;
666 * Routing changes might produce a better route than we last used;
667 * make sure we notice eventually, even if forwarding only for one
668 * destination and the cache is never replaced.
670 if (ip6_forward_rt.ro_rt) {
671 RTFREE(ip6_forward_rt.ro_rt);
672 ip6_forward_rt.ro_rt = 0;
674 if (ipsrcchk_rt.ro_rt) {
675 RTFREE(ipsrcchk_rt.ro_rt);
676 ipsrcchk_rt.ro_rt = 0;
684 * Drain off all datagram fragments.
689 if (frag6_doing_reass)
691 while (ip6q.ip6q_next != &ip6q) {
692 ip6stat.ip6s_fragdropped++;
693 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
694 frag6_freef(ip6q.ip6q_next);