1 /* $FreeBSD: src/sys/netinet6/frag6.c,v 1.2.2.6 2002/04/28 05:40:26 suz Exp $ */
2 /* $KAME: frag6.c,v 1.33 2002/01/07 11:34:48 kjc Exp $ */
5 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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.
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)
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33 #include <sys/param.h>
34 #include <sys/systm.h>
35 #include <sys/malloc.h>
37 #include <sys/domain.h>
38 #include <sys/protosw.h>
39 #include <sys/socket.h>
40 #include <sys/errno.h>
42 #include <sys/kernel.h>
43 #include <sys/syslog.h>
46 #include <net/route.h>
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>
54 #include <net/net_osdep.h>
57 * Define it to get a correct behavior on per-interface statistics.
58 * You will need to perform an extra routing table lookup, per fragment,
59 * to do it. This may, or may not be, a performance hit.
61 #define IN6_IFSTAT_STRICT
63 static void frag6_enq __P((struct ip6asfrag *, struct ip6asfrag *));
64 static void frag6_deq __P((struct ip6asfrag *));
65 static void frag6_insque __P((struct ip6q *, struct ip6q *));
66 static void frag6_remque __P((struct ip6q *));
67 static void frag6_freef __P((struct ip6q *));
69 /* XXX we eventually need splreass6, or some real semaphore */
70 int frag6_doing_reass;
71 u_int frag6_nfragpackets;
72 struct ip6q ip6q; /* ip6 reassemble queue */
75 MALLOC_DEFINE(M_FTABLE, "fragment", "fragment reassembly header");
78 * Initialise reassembly queue and fragment identifier.
85 ip6_maxfragpackets = nmbclusters / 4;
88 * in many cases, random() here does NOT return random number
89 * as initialization during bootstrap time occur in fixed order.
92 ip6_id = random() ^ tv.tv_usec;
93 ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q;
97 * In RFC2460, fragment and reassembly rule do not agree with each other,
98 * in terms of next header field handling in fragment header.
99 * While the sender will use the same value for all of the fragmented packets,
100 * receiver is suggested not to check the consistency.
102 * fragment rule (p20):
103 * (2) A Fragment header containing:
104 * The Next Header value that identifies the first header of
105 * the Fragmentable Part of the original packet.
106 * -> next header field is same for all fragments
108 * reassembly rule (p21):
109 * The Next Header field of the last header of the Unfragmentable
110 * Part is obtained from the Next Header field of the first
111 * fragment's Fragment header.
112 * -> should grab it from the first fragment only
114 * The following note also contradicts with fragment rule - noone is going to
115 * send different fragment with different next header field.
117 * additional note (p22):
118 * The Next Header values in the Fragment headers of different
119 * fragments of the same original packet may differ. Only the value
120 * from the Offset zero fragment packet is used for reassembly.
121 * -> should grab it from the first fragment only
123 * There is no explicit reason given in the RFC. Historical reason maybe?
129 frag6_input(mp, offp, proto)
133 struct mbuf *m = *mp, *t;
135 struct ip6_frag *ip6f;
137 struct ip6asfrag *af6, *ip6af, *af6dwn;
138 int offset = *offp, nxt, i, next;
140 int fragoff, frgpartlen; /* must be larger than u_int16_t */
141 struct ifnet *dstifp;
142 #ifdef IN6_IFSTAT_STRICT
143 static struct route_in6 ro;
144 struct sockaddr_in6 *dst;
147 ip6 = mtod(m, struct ip6_hdr *);
148 #ifndef PULLDOWN_TEST
149 IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE);
150 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
152 IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
158 #ifdef IN6_IFSTAT_STRICT
159 /* find the destination interface of the packet. */
160 dst = (struct sockaddr_in6 *)&ro.ro_dst;
162 && ((ro.ro_rt->rt_flags & RTF_UP) == 0
163 || !IN6_ARE_ADDR_EQUAL(&dst->sin6_addr, &ip6->ip6_dst))) {
165 ro.ro_rt = (struct rtentry *)0;
167 if (ro.ro_rt == NULL) {
168 bzero(dst, sizeof(*dst));
169 dst->sin6_family = AF_INET6;
170 dst->sin6_len = sizeof(struct sockaddr_in6);
171 dst->sin6_addr = ip6->ip6_dst;
173 rtalloc((struct route *)&ro);
174 if (ro.ro_rt != NULL && ro.ro_rt->rt_ifa != NULL)
175 dstifp = ((struct in6_ifaddr *)ro.ro_rt->rt_ifa)->ia_ifp;
177 /* we are violating the spec, this is not the destination interface */
178 if ((m->m_flags & M_PKTHDR) != 0)
179 dstifp = m->m_pkthdr.rcvif;
182 /* jumbo payload can't contain a fragment header */
183 if (ip6->ip6_plen == 0) {
184 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
185 in6_ifstat_inc(dstifp, ifs6_reass_fail);
190 * check whether fragment packet's fragment length is
191 * multiple of 8 octets.
192 * sizeof(struct ip6_frag) == 8
193 * sizeof(struct ip6_hdr) = 40
195 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
196 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
197 icmp6_error(m, ICMP6_PARAM_PROB,
198 ICMP6_PARAMPROB_HEADER,
199 offsetof(struct ip6_hdr, ip6_plen));
200 in6_ifstat_inc(dstifp, ifs6_reass_fail);
204 ip6stat.ip6s_fragments++;
205 in6_ifstat_inc(dstifp, ifs6_reass_reqd);
207 /* offset now points to data portion */
208 offset += sizeof(struct ip6_frag);
210 frag6_doing_reass = 1;
212 for (q6 = ip6q.ip6q_next; q6 != &ip6q; q6 = q6->ip6q_next)
213 if (ip6f->ip6f_ident == q6->ip6q_ident &&
214 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
215 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst))
220 * the first fragment to arrive, create a reassembly queue.
225 * Enforce upper bound on number of fragmented packets
226 * for which we attempt reassembly;
227 * If maxfrag is 0, never accept fragments.
228 * If maxfrag is -1, accept all fragments without limitation.
230 if (ip6_maxfragpackets < 0)
232 else if (frag6_nfragpackets >= (u_int)ip6_maxfragpackets)
234 frag6_nfragpackets++;
235 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE,
239 bzero(q6, sizeof(*q6));
241 frag6_insque(q6, &ip6q);
243 /* ip6q_nxt will be filled afterwards, from 1st fragment */
244 q6->ip6q_down = q6->ip6q_up = (struct ip6asfrag *)q6;
246 q6->ip6q_nxtp = (u_char *)nxtp;
248 q6->ip6q_ident = ip6f->ip6f_ident;
249 q6->ip6q_arrive = 0; /* Is it used anywhere? */
250 q6->ip6q_ttl = IPV6_FRAGTTL;
251 q6->ip6q_src = ip6->ip6_src;
252 q6->ip6q_dst = ip6->ip6_dst;
253 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
257 * If it's the 1st fragment, record the length of the
258 * unfragmentable part and the next header of the fragment header.
260 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
262 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr)
263 - sizeof(struct ip6_frag);
264 q6->ip6q_nxt = ip6f->ip6f_nxt;
268 * Check that the reassembled packet would not exceed 65535 bytes
270 * If it would exceed, discard the fragment and return an ICMP error.
272 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
273 if (q6->ip6q_unfrglen >= 0) {
274 /* The 1st fragment has already arrived. */
275 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
276 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
277 offset - sizeof(struct ip6_frag) +
278 offsetof(struct ip6_frag, ip6f_offlg));
279 frag6_doing_reass = 0;
280 return(IPPROTO_DONE);
283 else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
284 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
285 offset - sizeof(struct ip6_frag) +
286 offsetof(struct ip6_frag, ip6f_offlg));
287 frag6_doing_reass = 0;
288 return(IPPROTO_DONE);
291 * If it's the first fragment, do the above check for each
292 * fragment already stored in the reassembly queue.
295 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
297 af6dwn = af6->ip6af_down;
299 if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen >
301 struct mbuf *merr = IP6_REASS_MBUF(af6);
302 struct ip6_hdr *ip6err;
303 int erroff = af6->ip6af_offset;
305 /* dequeue the fragment. */
309 /* adjust pointer. */
310 ip6err = mtod(merr, struct ip6_hdr *);
313 * Restore source and destination addresses
314 * in the erroneous IPv6 header.
316 ip6err->ip6_src = q6->ip6q_src;
317 ip6err->ip6_dst = q6->ip6q_dst;
319 icmp6_error(merr, ICMP6_PARAM_PROB,
320 ICMP6_PARAMPROB_HEADER,
321 erroff - sizeof(struct ip6_frag) +
322 offsetof(struct ip6_frag, ip6f_offlg));
327 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FTABLE,
331 bzero(ip6af, sizeof(*ip6af));
332 ip6af->ip6af_head = ip6->ip6_flow;
333 ip6af->ip6af_len = ip6->ip6_plen;
334 ip6af->ip6af_nxt = ip6->ip6_nxt;
335 ip6af->ip6af_hlim = ip6->ip6_hlim;
336 ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG;
337 ip6af->ip6af_off = fragoff;
338 ip6af->ip6af_frglen = frgpartlen;
339 ip6af->ip6af_offset = offset;
340 IP6_REASS_MBUF(ip6af) = m;
343 af6 = (struct ip6asfrag *)q6;
348 * Find a segment which begins after this one does.
350 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
351 af6 = af6->ip6af_down)
352 if (af6->ip6af_off > ip6af->ip6af_off)
357 * If there is a preceding segment, it may provide some of
358 * our data already. If so, drop the data from the incoming
359 * segment. If it provides all of our data, drop us.
361 if (af6->ip6af_up != (struct ip6asfrag *)q6) {
362 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
365 if (i >= ip6af->ip6af_frglen)
367 m_adj(IP6_REASS_MBUF(ip6af), i);
368 ip6af->ip6af_off += i;
369 ip6af->ip6af_frglen -= i;
374 * While we overlap succeeding segments trim them or,
375 * if they are completely covered, dequeue them.
377 while (af6 != (struct ip6asfrag *)q6 &&
378 ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) {
379 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
380 if (i < af6->ip6af_frglen) {
381 af6->ip6af_frglen -= i;
383 m_adj(IP6_REASS_MBUF(af6), i);
386 af6 = af6->ip6af_down;
387 m_freem(IP6_REASS_MBUF(af6->ip6af_up));
388 frag6_deq(af6->ip6af_up);
392 * If the incoming framgent overlaps some existing fragments in
393 * the reassembly queue, drop it, since it is dangerous to override
394 * existing fragments from a security point of view.
396 if (af6->ip6af_up != (struct ip6asfrag *)q6) {
397 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
400 #if 0 /* suppress the noisy log */
401 log(LOG_ERR, "%d bytes of a fragment from %s "
402 "overlaps the previous fragment\n",
403 i, ip6_sprintf(&q6->ip6q_src));
405 free(ip6af, M_FTABLE);
409 if (af6 != (struct ip6asfrag *)q6) {
410 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
412 #if 0 /* suppress the noisy log */
413 log(LOG_ERR, "%d bytes of a fragment from %s "
414 "overlaps the succeeding fragment",
415 i, ip6_sprintf(&q6->ip6q_src));
417 free(ip6af, M_FTABLE);
426 * Stick new segment in its place;
427 * check for complete reassembly.
428 * Move to front of packet queue, as we are
429 * the most recently active fragmented packet.
431 frag6_enq(ip6af, af6->ip6af_up);
433 if (q6 != ip6q.ip6q_next) {
435 frag6_insque(q6, &ip6q);
439 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
440 af6 = af6->ip6af_down) {
441 if (af6->ip6af_off != next) {
442 frag6_doing_reass = 0;
445 next += af6->ip6af_frglen;
447 if (af6->ip6af_up->ip6af_mff) {
448 frag6_doing_reass = 0;
453 * Reassembly is complete; concatenate fragments.
455 ip6af = q6->ip6q_down;
456 t = m = IP6_REASS_MBUF(ip6af);
457 af6 = ip6af->ip6af_down;
459 while (af6 != (struct ip6asfrag *)q6) {
460 af6dwn = af6->ip6af_down;
464 t->m_next = IP6_REASS_MBUF(af6);
465 m_adj(t->m_next, af6->ip6af_offset);
470 /* adjust offset to point where the original next header starts */
471 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
472 free(ip6af, M_FTABLE);
473 ip6 = mtod(m, struct ip6_hdr *);
474 ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr));
475 ip6->ip6_src = q6->ip6q_src;
476 ip6->ip6_dst = q6->ip6q_dst;
479 *q6->ip6q_nxtp = (u_char)(nxt & 0xff);
483 * Delete frag6 header with as a few cost as possible.
485 if (offset < m->m_len) {
486 ovbcopy((caddr_t)ip6, (caddr_t)ip6 + sizeof(struct ip6_frag),
488 m->m_data += sizeof(struct ip6_frag);
489 m->m_len -= sizeof(struct ip6_frag);
491 /* this comes with no copy if the boundary is on cluster */
492 if ((t = m_split(m, offset, M_DONTWAIT)) == NULL) {
495 frag6_nfragpackets--;
498 m_adj(t, sizeof(struct ip6_frag));
503 * Store NXT to the original.
506 char *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */
512 frag6_nfragpackets--;
514 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
516 for (t = m; t; t = t->m_next)
518 m->m_pkthdr.len = plen;
521 ip6stat.ip6s_reassembled++;
522 in6_ifstat_inc(dstifp, ifs6_reass_ok);
525 * Tell launch routine the next header
531 frag6_doing_reass = 0;
535 in6_ifstat_inc(dstifp, ifs6_reass_fail);
536 ip6stat.ip6s_fragdropped++;
538 frag6_doing_reass = 0;
543 * Free a fragment reassembly header and all
544 * associated datagrams.
550 struct ip6asfrag *af6, *down6;
552 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
554 struct mbuf *m = IP6_REASS_MBUF(af6);
556 down6 = af6->ip6af_down;
560 * Return ICMP time exceeded error for the 1st fragment.
561 * Just free other fragments.
563 if (af6->ip6af_off == 0) {
567 ip6 = mtod(m, struct ip6_hdr *);
569 /* restoure source and destination addresses */
570 ip6->ip6_src = q6->ip6q_src;
571 ip6->ip6_dst = q6->ip6q_dst;
573 icmp6_error(m, ICMP6_TIME_EXCEEDED,
574 ICMP6_TIME_EXCEED_REASSEMBLY, 0);
581 frag6_nfragpackets--;
585 * Put an ip fragment on a reassembly chain.
586 * Like insque, but pointers in middle of structure.
590 struct ip6asfrag *af6, *up6;
593 af6->ip6af_down = up6->ip6af_down;
594 up6->ip6af_down->ip6af_up = af6;
595 up6->ip6af_down = af6;
599 * To frag6_enq as remque is to insque.
603 struct ip6asfrag *af6;
605 af6->ip6af_up->ip6af_down = af6->ip6af_down;
606 af6->ip6af_down->ip6af_up = af6->ip6af_up;
610 frag6_insque(new, old)
611 struct ip6q *new, *old;
613 new->ip6q_prev = old;
614 new->ip6q_next = old->ip6q_next;
615 old->ip6q_next->ip6q_prev= new;
616 old->ip6q_next = new;
623 p6->ip6q_prev->ip6q_next = p6->ip6q_next;
624 p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
628 * IPv6 reassembling timer processing;
629 * if a timer expires on a reassembly
638 frag6_doing_reass = 1;
641 while (q6 != &ip6q) {
644 if (q6->ip6q_prev->ip6q_ttl == 0) {
645 ip6stat.ip6s_fragtimeout++;
646 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
647 frag6_freef(q6->ip6q_prev);
651 * If we are over the maximum number of fragments
652 * (due to the limit being lowered), drain off
653 * enough to get down to the new limit.
655 while (frag6_nfragpackets > (u_int)ip6_maxfragpackets &&
657 ip6stat.ip6s_fragoverflow++;
658 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
659 frag6_freef(ip6q.ip6q_prev);
661 frag6_doing_reass = 0;
665 * Routing changes might produce a better route than we last used;
666 * make sure we notice eventually, even if forwarding only for one
667 * destination and the cache is never replaced.
669 if (ip6_forward_rt.ro_rt) {
670 RTFREE(ip6_forward_rt.ro_rt);
671 ip6_forward_rt.ro_rt = 0;
673 if (ipsrcchk_rt.ro_rt) {
674 RTFREE(ipsrcchk_rt.ro_rt);
675 ipsrcchk_rt.ro_rt = 0;
683 * Drain off all datagram fragments.
688 if (frag6_doing_reass)
690 while (ip6q.ip6q_next != &ip6q) {
691 ip6stat.ip6s_fragdropped++;
692 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
693 frag6_freef(ip6q.ip6q_next);