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1/*
2 * IPv6 fragment reassembly
3 * Linux INET6 implementation
4 *
5 * Authors:
6 * Pedro Roque <roque@di.fc.ul.pt>
7 *
8 * Based on: net/ipv4/ip_fragment.c
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
14 */
15
16/*
17 * Fixes:
18 * Andi Kleen Make it work with multiple hosts.
19 * More RFC compliance.
20 *
21 * Horst von Brand Add missing #include <linux/string.h>
22 * Alexey Kuznetsov SMP races, threading, cleanup.
23 * Patrick McHardy LRU queue of frag heads for evictor.
24 * Mitsuru KANDA @USAGI Register inet6_protocol{}.
25 * David Stevens and
26 * YOSHIFUJI,H. @USAGI Always remove fragment header to
27 * calculate ICV correctly.
28 */
29#include <linux/errno.h>
30#include <linux/types.h>
31#include <linux/string.h>
32#include <linux/socket.h>
33#include <linux/sockios.h>
34#include <linux/jiffies.h>
35#include <linux/net.h>
36#include <linux/list.h>
37#include <linux/netdevice.h>
38#include <linux/in6.h>
39#include <linux/ipv6.h>
40#include <linux/icmpv6.h>
41#include <linux/random.h>
42#include <linux/jhash.h>
43#include <linux/skbuff.h>
44#include <linux/slab.h>
45
46#include <net/sock.h>
47#include <net/snmp.h>
48
49#include <net/ipv6.h>
50#include <net/ip6_route.h>
51#include <net/protocol.h>
52#include <net/transp_v6.h>
53#include <net/rawv6.h>
54#include <net/ndisc.h>
55#include <net/addrconf.h>
56#include <net/inet_frag.h>
57
58struct ip6frag_skb_cb
59{
60 struct inet6_skb_parm h;
61 int offset;
62};
63
64#define FRAG6_CB(skb) ((struct ip6frag_skb_cb*)((skb)->cb))
65
66
67/*
68 * Equivalent of ipv4 struct ipq
69 */
70
71struct frag_queue
72{
73 struct inet_frag_queue q;
74
75 __be32 id; /* fragment id */
76 u32 user;
77 struct in6_addr saddr;
78 struct in6_addr daddr;
79
80 int iif;
81 unsigned int csum;
82 __u16 nhoffset;
83};
84
85static struct inet_frags ip6_frags;
86
87int ip6_frag_nqueues(struct net *net)
88{
89 return net->ipv6.frags.nqueues;
90}
91
92int ip6_frag_mem(struct net *net)
93{
94 return atomic_read(&net->ipv6.frags.mem);
95}
96
97static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
98 struct net_device *dev);
99
100/*
101 * callers should be careful not to use the hash value outside the ipfrag_lock
102 * as doing so could race with ipfrag_hash_rnd being recalculated.
103 */
104unsigned int inet6_hash_frag(__be32 id, const struct in6_addr *saddr,
105 const struct in6_addr *daddr, u32 rnd)
106{
107 u32 c;
108
109 c = jhash_3words((__force u32)saddr->s6_addr32[0],
110 (__force u32)saddr->s6_addr32[1],
111 (__force u32)saddr->s6_addr32[2],
112 rnd);
113
114 c = jhash_3words((__force u32)saddr->s6_addr32[3],
115 (__force u32)daddr->s6_addr32[0],
116 (__force u32)daddr->s6_addr32[1],
117 c);
118
119 c = jhash_3words((__force u32)daddr->s6_addr32[2],
120 (__force u32)daddr->s6_addr32[3],
121 (__force u32)id,
122 c);
123
124 return c & (INETFRAGS_HASHSZ - 1);
125}
126EXPORT_SYMBOL_GPL(inet6_hash_frag);
127
128static unsigned int ip6_hashfn(struct inet_frag_queue *q)
129{
130 struct frag_queue *fq;
131
132 fq = container_of(q, struct frag_queue, q);
133 return inet6_hash_frag(fq->id, &fq->saddr, &fq->daddr, ip6_frags.rnd);
134}
135
136int ip6_frag_match(struct inet_frag_queue *q, void *a)
137{
138 struct frag_queue *fq;
139 struct ip6_create_arg *arg = a;
140
141 fq = container_of(q, struct frag_queue, q);
142 return (fq->id == arg->id && fq->user == arg->user &&
143 ipv6_addr_equal(&fq->saddr, arg->src) &&
144 ipv6_addr_equal(&fq->daddr, arg->dst));
145}
146EXPORT_SYMBOL(ip6_frag_match);
147
148void ip6_frag_init(struct inet_frag_queue *q, void *a)
149{
150 struct frag_queue *fq = container_of(q, struct frag_queue, q);
151 struct ip6_create_arg *arg = a;
152
153 fq->id = arg->id;
154 fq->user = arg->user;
155 ipv6_addr_copy(&fq->saddr, arg->src);
156 ipv6_addr_copy(&fq->daddr, arg->dst);
157}
158EXPORT_SYMBOL(ip6_frag_init);
159
160/* Destruction primitives. */
161
162static __inline__ void fq_put(struct frag_queue *fq)
163{
164 inet_frag_put(&fq->q, &ip6_frags);
165}
166
167/* Kill fq entry. It is not destroyed immediately,
168 * because caller (and someone more) holds reference count.
169 */
170static __inline__ void fq_kill(struct frag_queue *fq)
171{
172 inet_frag_kill(&fq->q, &ip6_frags);
173}
174
175static void ip6_evictor(struct net *net, struct inet6_dev *idev)
176{
177 int evicted;
178
179 evicted = inet_frag_evictor(&net->ipv6.frags, &ip6_frags);
180 if (evicted)
181 IP6_ADD_STATS_BH(net, idev, IPSTATS_MIB_REASMFAILS, evicted);
182}
183
184static void ip6_frag_expire(unsigned long data)
185{
186 struct frag_queue *fq;
187 struct net_device *dev = NULL;
188 struct net *net;
189
190 fq = container_of((struct inet_frag_queue *)data, struct frag_queue, q);
191
192 spin_lock(&fq->q.lock);
193
194 if (fq->q.last_in & INET_FRAG_COMPLETE)
195 goto out;
196
197 fq_kill(fq);
198
199 net = container_of(fq->q.net, struct net, ipv6.frags);
200 rcu_read_lock();
201 dev = dev_get_by_index_rcu(net, fq->iif);
202 if (!dev)
203 goto out_rcu_unlock;
204
205 IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMTIMEOUT);
206 IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
207
208 /* Don't send error if the first segment did not arrive. */
209 if (!(fq->q.last_in & INET_FRAG_FIRST_IN) || !fq->q.fragments)
210 goto out_rcu_unlock;
211
212 /*
213 But use as source device on which LAST ARRIVED
214 segment was received. And do not use fq->dev
215 pointer directly, device might already disappeared.
216 */
217 fq->q.fragments->dev = dev;
218 icmpv6_send(fq->q.fragments, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0);
219out_rcu_unlock:
220 rcu_read_unlock();
221out:
222 spin_unlock(&fq->q.lock);
223 fq_put(fq);
224}
225
226static __inline__ struct frag_queue *
227fq_find(struct net *net, __be32 id, const struct in6_addr *src, const struct in6_addr *dst)
228{
229 struct inet_frag_queue *q;
230 struct ip6_create_arg arg;
231 unsigned int hash;
232
233 arg.id = id;
234 arg.user = IP6_DEFRAG_LOCAL_DELIVER;
235 arg.src = src;
236 arg.dst = dst;
237
238 read_lock(&ip6_frags.lock);
239 hash = inet6_hash_frag(id, src, dst, ip6_frags.rnd);
240
241 q = inet_frag_find(&net->ipv6.frags, &ip6_frags, &arg, hash);
242 if (q == NULL)
243 return NULL;
244
245 return container_of(q, struct frag_queue, q);
246}
247
248static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
249 struct frag_hdr *fhdr, int nhoff)
250{
251 struct sk_buff *prev, *next;
252 struct net_device *dev;
253 int offset, end;
254 struct net *net = dev_net(skb_dst(skb)->dev);
255
256 if (fq->q.last_in & INET_FRAG_COMPLETE)
257 goto err;
258
259 offset = ntohs(fhdr->frag_off) & ~0x7;
260 end = offset + (ntohs(ipv6_hdr(skb)->payload_len) -
261 ((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1)));
262
263 if ((unsigned int)end > IPV6_MAXPLEN) {
264 IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
265 IPSTATS_MIB_INHDRERRORS);
266 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
267 ((u8 *)&fhdr->frag_off -
268 skb_network_header(skb)));
269 return -1;
270 }
271
272 if (skb->ip_summed == CHECKSUM_COMPLETE) {
273 const unsigned char *nh = skb_network_header(skb);
274 skb->csum = csum_sub(skb->csum,
275 csum_partial(nh, (u8 *)(fhdr + 1) - nh,
276 0));
277 }
278
279 /* Is this the final fragment? */
280 if (!(fhdr->frag_off & htons(IP6_MF))) {
281 /* If we already have some bits beyond end
282 * or have different end, the segment is corrupted.
283 */
284 if (end < fq->q.len ||
285 ((fq->q.last_in & INET_FRAG_LAST_IN) && end != fq->q.len))
286 goto err;
287 fq->q.last_in |= INET_FRAG_LAST_IN;
288 fq->q.len = end;
289 } else {
290 /* Check if the fragment is rounded to 8 bytes.
291 * Required by the RFC.
292 */
293 if (end & 0x7) {
294 /* RFC2460 says always send parameter problem in
295 * this case. -DaveM
296 */
297 IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
298 IPSTATS_MIB_INHDRERRORS);
299 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
300 offsetof(struct ipv6hdr, payload_len));
301 return -1;
302 }
303 if (end > fq->q.len) {
304 /* Some bits beyond end -> corruption. */
305 if (fq->q.last_in & INET_FRAG_LAST_IN)
306 goto err;
307 fq->q.len = end;
308 }
309 }
310
311 if (end == offset)
312 goto err;
313
314 /* Point into the IP datagram 'data' part. */
315 if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
316 goto err;
317
318 if (pskb_trim_rcsum(skb, end - offset))
319 goto err;
320
321 /* Find out which fragments are in front and at the back of us
322 * in the chain of fragments so far. We must know where to put
323 * this fragment, right?
324 */
325 prev = fq->q.fragments_tail;
326 if (!prev || FRAG6_CB(prev)->offset < offset) {
327 next = NULL;
328 goto found;
329 }
330 prev = NULL;
331 for(next = fq->q.fragments; next != NULL; next = next->next) {
332 if (FRAG6_CB(next)->offset >= offset)
333 break; /* bingo! */
334 prev = next;
335 }
336
337found:
338 /* RFC5722, Section 4:
339 * When reassembling an IPv6 datagram, if
340 * one or more its constituent fragments is determined to be an
341 * overlapping fragment, the entire datagram (and any constituent
342 * fragments, including those not yet received) MUST be silently
343 * discarded.
344 */
345
346 /* Check for overlap with preceding fragment. */
347 if (prev &&
348 (FRAG6_CB(prev)->offset + prev->len) > offset)
349 goto discard_fq;
350
351 /* Look for overlap with succeeding segment. */
352 if (next && FRAG6_CB(next)->offset < end)
353 goto discard_fq;
354
355 FRAG6_CB(skb)->offset = offset;
356
357 /* Insert this fragment in the chain of fragments. */
358 skb->next = next;
359 if (!next)
360 fq->q.fragments_tail = skb;
361 if (prev)
362 prev->next = skb;
363 else
364 fq->q.fragments = skb;
365
366 dev = skb->dev;
367 if (dev) {
368 fq->iif = dev->ifindex;
369 skb->dev = NULL;
370 }
371 fq->q.stamp = skb->tstamp;
372 fq->q.meat += skb->len;
373 atomic_add(skb->truesize, &fq->q.net->mem);
374
375 /* The first fragment.
376 * nhoffset is obtained from the first fragment, of course.
377 */
378 if (offset == 0) {
379 fq->nhoffset = nhoff;
380 fq->q.last_in |= INET_FRAG_FIRST_IN;
381 }
382
383 if (fq->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
384 fq->q.meat == fq->q.len)
385 return ip6_frag_reasm(fq, prev, dev);
386
387 write_lock(&ip6_frags.lock);
388 list_move_tail(&fq->q.lru_list, &fq->q.net->lru_list);
389 write_unlock(&ip6_frags.lock);
390 return -1;
391
392discard_fq:
393 fq_kill(fq);
394err:
395 IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
396 IPSTATS_MIB_REASMFAILS);
397 kfree_skb(skb);
398 return -1;
399}
400
401/*
402 * Check if this packet is complete.
403 * Returns NULL on failure by any reason, and pointer
404 * to current nexthdr field in reassembled frame.
405 *
406 * It is called with locked fq, and caller must check that
407 * queue is eligible for reassembly i.e. it is not COMPLETE,
408 * the last and the first frames arrived and all the bits are here.
409 */
410static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
411 struct net_device *dev)
412{
413 struct net *net = container_of(fq->q.net, struct net, ipv6.frags);
414 struct sk_buff *fp, *head = fq->q.fragments;
415 int payload_len;
416 unsigned int nhoff;
417
418 fq_kill(fq);
419
420 /* Make the one we just received the head. */
421 if (prev) {
422 head = prev->next;
423 fp = skb_clone(head, GFP_ATOMIC);
424
425 if (!fp)
426 goto out_oom;
427
428 fp->next = head->next;
429 if (!fp->next)
430 fq->q.fragments_tail = fp;
431 prev->next = fp;
432
433 skb_morph(head, fq->q.fragments);
434 head->next = fq->q.fragments->next;
435
436 kfree_skb(fq->q.fragments);
437 fq->q.fragments = head;
438 }
439
440 WARN_ON(head == NULL);
441 WARN_ON(FRAG6_CB(head)->offset != 0);
442
443 /* Unfragmented part is taken from the first segment. */
444 payload_len = ((head->data - skb_network_header(head)) -
445 sizeof(struct ipv6hdr) + fq->q.len -
446 sizeof(struct frag_hdr));
447 if (payload_len > IPV6_MAXPLEN)
448 goto out_oversize;
449
450 /* Head of list must not be cloned. */
451 if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
452 goto out_oom;
453
454 /* If the first fragment is fragmented itself, we split
455 * it to two chunks: the first with data and paged part
456 * and the second, holding only fragments. */
457 if (skb_has_frag_list(head)) {
458 struct sk_buff *clone;
459 int i, plen = 0;
460
461 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
462 goto out_oom;
463 clone->next = head->next;
464 head->next = clone;
465 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
466 skb_frag_list_init(head);
467 for (i=0; i<skb_shinfo(head)->nr_frags; i++)
468 plen += skb_shinfo(head)->frags[i].size;
469 clone->len = clone->data_len = head->data_len - plen;
470 head->data_len -= clone->len;
471 head->len -= clone->len;
472 clone->csum = 0;
473 clone->ip_summed = head->ip_summed;
474 atomic_add(clone->truesize, &fq->q.net->mem);
475 }
476
477 /* We have to remove fragment header from datagram and to relocate
478 * header in order to calculate ICV correctly. */
479 nhoff = fq->nhoffset;
480 skb_network_header(head)[nhoff] = skb_transport_header(head)[0];
481 memmove(head->head + sizeof(struct frag_hdr), head->head,
482 (head->data - head->head) - sizeof(struct frag_hdr));
483 head->mac_header += sizeof(struct frag_hdr);
484 head->network_header += sizeof(struct frag_hdr);
485
486 skb_shinfo(head)->frag_list = head->next;
487 skb_reset_transport_header(head);
488 skb_push(head, head->data - skb_network_header(head));
489
490 for (fp=head->next; fp; fp = fp->next) {
491 head->data_len += fp->len;
492 head->len += fp->len;
493 if (head->ip_summed != fp->ip_summed)
494 head->ip_summed = CHECKSUM_NONE;
495 else if (head->ip_summed == CHECKSUM_COMPLETE)
496 head->csum = csum_add(head->csum, fp->csum);
497 head->truesize += fp->truesize;
498 }
499 atomic_sub(head->truesize, &fq->q.net->mem);
500
501 head->next = NULL;
502 head->dev = dev;
503 head->tstamp = fq->q.stamp;
504 ipv6_hdr(head)->payload_len = htons(payload_len);
505 IP6CB(head)->nhoff = nhoff;
506
507 /* Yes, and fold redundant checksum back. 8) */
508 if (head->ip_summed == CHECKSUM_COMPLETE)
509 head->csum = csum_partial(skb_network_header(head),
510 skb_network_header_len(head),
511 head->csum);
512
513 rcu_read_lock();
514 IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
515 rcu_read_unlock();
516 fq->q.fragments = NULL;
517 fq->q.fragments_tail = NULL;
518 return 1;
519
520out_oversize:
521 if (net_ratelimit())
522 printk(KERN_DEBUG "ip6_frag_reasm: payload len = %d\n", payload_len);
523 goto out_fail;
524out_oom:
525 if (net_ratelimit())
526 printk(KERN_DEBUG "ip6_frag_reasm: no memory for reassembly\n");
527out_fail:
528 rcu_read_lock();
529 IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
530 rcu_read_unlock();
531 return -1;
532}
533
534static int ipv6_frag_rcv(struct sk_buff *skb)
535{
536 struct frag_hdr *fhdr;
537 struct frag_queue *fq;
538 const struct ipv6hdr *hdr = ipv6_hdr(skb);
539 struct net *net = dev_net(skb_dst(skb)->dev);
540
541 IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMREQDS);
542
543 /* Jumbo payload inhibits frag. header */
544 if (hdr->payload_len==0)
545 goto fail_hdr;
546
547 if (!pskb_may_pull(skb, (skb_transport_offset(skb) +
548 sizeof(struct frag_hdr))))
549 goto fail_hdr;
550
551 hdr = ipv6_hdr(skb);
552 fhdr = (struct frag_hdr *)skb_transport_header(skb);
553
554 if (!(fhdr->frag_off & htons(0xFFF9))) {
555 /* It is not a fragmented frame */
556 skb->transport_header += sizeof(struct frag_hdr);
557 IP6_INC_STATS_BH(net,
558 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMOKS);
559
560 IP6CB(skb)->nhoff = (u8 *)fhdr - skb_network_header(skb);
561 return 1;
562 }
563
564 if (atomic_read(&net->ipv6.frags.mem) > net->ipv6.frags.high_thresh)
565 ip6_evictor(net, ip6_dst_idev(skb_dst(skb)));
566
567 fq = fq_find(net, fhdr->identification, &hdr->saddr, &hdr->daddr);
568 if (fq != NULL) {
569 int ret;
570
571 spin_lock(&fq->q.lock);
572
573 ret = ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff);
574
575 spin_unlock(&fq->q.lock);
576 fq_put(fq);
577 return ret;
578 }
579
580 IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMFAILS);
581 kfree_skb(skb);
582 return -1;
583
584fail_hdr:
585 IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS);
586 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb_network_header_len(skb));
587 return -1;
588}
589
590static const struct inet6_protocol frag_protocol =
591{
592 .handler = ipv6_frag_rcv,
593 .flags = INET6_PROTO_NOPOLICY,
594};
595
596#ifdef CONFIG_SYSCTL
597static struct ctl_table ip6_frags_ns_ctl_table[] = {
598 {
599 .procname = "ip6frag_high_thresh",
600 .data = &init_net.ipv6.frags.high_thresh,
601 .maxlen = sizeof(int),
602 .mode = 0644,
603 .proc_handler = proc_dointvec
604 },
605 {
606 .procname = "ip6frag_low_thresh",
607 .data = &init_net.ipv6.frags.low_thresh,
608 .maxlen = sizeof(int),
609 .mode = 0644,
610 .proc_handler = proc_dointvec
611 },
612 {
613 .procname = "ip6frag_time",
614 .data = &init_net.ipv6.frags.timeout,
615 .maxlen = sizeof(int),
616 .mode = 0644,
617 .proc_handler = proc_dointvec_jiffies,
618 },
619 { }
620};
621
622static struct ctl_table ip6_frags_ctl_table[] = {
623 {
624 .procname = "ip6frag_secret_interval",
625 .data = &ip6_frags.secret_interval,
626 .maxlen = sizeof(int),
627 .mode = 0644,
628 .proc_handler = proc_dointvec_jiffies,
629 },
630 { }
631};
632
633static int __net_init ip6_frags_ns_sysctl_register(struct net *net)
634{
635 struct ctl_table *table;
636 struct ctl_table_header *hdr;
637
638 table = ip6_frags_ns_ctl_table;
639 if (!net_eq(net, &init_net)) {
640 table = kmemdup(table, sizeof(ip6_frags_ns_ctl_table), GFP_KERNEL);
641 if (table == NULL)
642 goto err_alloc;
643
644 table[0].data = &net->ipv6.frags.high_thresh;
645 table[1].data = &net->ipv6.frags.low_thresh;
646 table[2].data = &net->ipv6.frags.timeout;
647 }
648
649 hdr = register_net_sysctl_table(net, net_ipv6_ctl_path, table);
650 if (hdr == NULL)
651 goto err_reg;
652
653 net->ipv6.sysctl.frags_hdr = hdr;
654 return 0;
655
656err_reg:
657 if (!net_eq(net, &init_net))
658 kfree(table);
659err_alloc:
660 return -ENOMEM;
661}
662
663static void __net_exit ip6_frags_ns_sysctl_unregister(struct net *net)
664{
665 struct ctl_table *table;
666
667 table = net->ipv6.sysctl.frags_hdr->ctl_table_arg;
668 unregister_net_sysctl_table(net->ipv6.sysctl.frags_hdr);
669 if (!net_eq(net, &init_net))
670 kfree(table);
671}
672
673static struct ctl_table_header *ip6_ctl_header;
674
675static int ip6_frags_sysctl_register(void)
676{
677 ip6_ctl_header = register_net_sysctl_rotable(net_ipv6_ctl_path,
678 ip6_frags_ctl_table);
679 return ip6_ctl_header == NULL ? -ENOMEM : 0;
680}
681
682static void ip6_frags_sysctl_unregister(void)
683{
684 unregister_net_sysctl_table(ip6_ctl_header);
685}
686#else
687static inline int ip6_frags_ns_sysctl_register(struct net *net)
688{
689 return 0;
690}
691
692static inline void ip6_frags_ns_sysctl_unregister(struct net *net)
693{
694}
695
696static inline int ip6_frags_sysctl_register(void)
697{
698 return 0;
699}
700
701static inline void ip6_frags_sysctl_unregister(void)
702{
703}
704#endif
705
706static int __net_init ipv6_frags_init_net(struct net *net)
707{
708 net->ipv6.frags.high_thresh = IPV6_FRAG_HIGH_THRESH;
709 net->ipv6.frags.low_thresh = IPV6_FRAG_LOW_THRESH;
710 net->ipv6.frags.timeout = IPV6_FRAG_TIMEOUT;
711
712 inet_frags_init_net(&net->ipv6.frags);
713
714 return ip6_frags_ns_sysctl_register(net);
715}
716
717static void __net_exit ipv6_frags_exit_net(struct net *net)
718{
719 ip6_frags_ns_sysctl_unregister(net);
720 inet_frags_exit_net(&net->ipv6.frags, &ip6_frags);
721}
722
723static struct pernet_operations ip6_frags_ops = {
724 .init = ipv6_frags_init_net,
725 .exit = ipv6_frags_exit_net,
726};
727
728int __init ipv6_frag_init(void)
729{
730 int ret;
731
732 ret = inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT);
733 if (ret)
734 goto out;
735
736 ret = ip6_frags_sysctl_register();
737 if (ret)
738 goto err_sysctl;
739
740 ret = register_pernet_subsys(&ip6_frags_ops);
741 if (ret)
742 goto err_pernet;
743
744 ip6_frags.hashfn = ip6_hashfn;
745 ip6_frags.constructor = ip6_frag_init;
746 ip6_frags.destructor = NULL;
747 ip6_frags.skb_free = NULL;
748 ip6_frags.qsize = sizeof(struct frag_queue);
749 ip6_frags.match = ip6_frag_match;
750 ip6_frags.frag_expire = ip6_frag_expire;
751 ip6_frags.secret_interval = 10 * 60 * HZ;
752 inet_frags_init(&ip6_frags);
753out:
754 return ret;
755
756err_pernet:
757 ip6_frags_sysctl_unregister();
758err_sysctl:
759 inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
760 goto out;
761}
762
763void ipv6_frag_exit(void)
764{
765 inet_frags_fini(&ip6_frags);
766 ip6_frags_sysctl_unregister();
767 unregister_pernet_subsys(&ip6_frags_ops);
768 inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
769}
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * IPv6 fragment reassembly
4 * Linux INET6 implementation
5 *
6 * Authors:
7 * Pedro Roque <roque@di.fc.ul.pt>
8 *
9 * Based on: net/ipv4/ip_fragment.c
10 */
11
12/*
13 * Fixes:
14 * Andi Kleen Make it work with multiple hosts.
15 * More RFC compliance.
16 *
17 * Horst von Brand Add missing #include <linux/string.h>
18 * Alexey Kuznetsov SMP races, threading, cleanup.
19 * Patrick McHardy LRU queue of frag heads for evictor.
20 * Mitsuru KANDA @USAGI Register inet6_protocol{}.
21 * David Stevens and
22 * YOSHIFUJI,H. @USAGI Always remove fragment header to
23 * calculate ICV correctly.
24 */
25
26#define pr_fmt(fmt) "IPv6: " fmt
27
28#include <linux/errno.h>
29#include <linux/types.h>
30#include <linux/string.h>
31#include <linux/socket.h>
32#include <linux/sockios.h>
33#include <linux/jiffies.h>
34#include <linux/net.h>
35#include <linux/list.h>
36#include <linux/netdevice.h>
37#include <linux/in6.h>
38#include <linux/ipv6.h>
39#include <linux/icmpv6.h>
40#include <linux/random.h>
41#include <linux/jhash.h>
42#include <linux/skbuff.h>
43#include <linux/slab.h>
44#include <linux/export.h>
45#include <linux/tcp.h>
46#include <linux/udp.h>
47
48#include <net/sock.h>
49#include <net/snmp.h>
50
51#include <net/ipv6.h>
52#include <net/ip6_route.h>
53#include <net/protocol.h>
54#include <net/transp_v6.h>
55#include <net/rawv6.h>
56#include <net/ndisc.h>
57#include <net/addrconf.h>
58#include <net/ipv6_frag.h>
59#include <net/inet_ecn.h>
60
61static const char ip6_frag_cache_name[] = "ip6-frags";
62
63static u8 ip6_frag_ecn(const struct ipv6hdr *ipv6h)
64{
65 return 1 << (ipv6_get_dsfield(ipv6h) & INET_ECN_MASK);
66}
67
68static struct inet_frags ip6_frags;
69
70static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *skb,
71 struct sk_buff *prev_tail, struct net_device *dev);
72
73static void ip6_frag_expire(struct timer_list *t)
74{
75 struct inet_frag_queue *frag = from_timer(frag, t, timer);
76 struct frag_queue *fq;
77
78 fq = container_of(frag, struct frag_queue, q);
79
80 ip6frag_expire_frag_queue(fq->q.fqdir->net, fq);
81}
82
83static struct frag_queue *
84fq_find(struct net *net, __be32 id, const struct ipv6hdr *hdr, int iif)
85{
86 struct frag_v6_compare_key key = {
87 .id = id,
88 .saddr = hdr->saddr,
89 .daddr = hdr->daddr,
90 .user = IP6_DEFRAG_LOCAL_DELIVER,
91 .iif = iif,
92 };
93 struct inet_frag_queue *q;
94
95 if (!(ipv6_addr_type(&hdr->daddr) & (IPV6_ADDR_MULTICAST |
96 IPV6_ADDR_LINKLOCAL)))
97 key.iif = 0;
98
99 q = inet_frag_find(net->ipv6.fqdir, &key);
100 if (!q)
101 return NULL;
102
103 return container_of(q, struct frag_queue, q);
104}
105
106static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
107 struct frag_hdr *fhdr, int nhoff,
108 u32 *prob_offset)
109{
110 struct net *net = dev_net(skb_dst(skb)->dev);
111 int offset, end, fragsize;
112 struct sk_buff *prev_tail;
113 struct net_device *dev;
114 int err = -ENOENT;
115 SKB_DR(reason);
116 u8 ecn;
117
118 /* If reassembly is already done, @skb must be a duplicate frag. */
119 if (fq->q.flags & INET_FRAG_COMPLETE) {
120 SKB_DR_SET(reason, DUP_FRAG);
121 goto err;
122 }
123
124 err = -EINVAL;
125 offset = ntohs(fhdr->frag_off) & ~0x7;
126 end = offset + (ntohs(ipv6_hdr(skb)->payload_len) -
127 ((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1)));
128
129 if ((unsigned int)end > IPV6_MAXPLEN) {
130 *prob_offset = (u8 *)&fhdr->frag_off - skb_network_header(skb);
131 /* note that if prob_offset is set, the skb is freed elsewhere,
132 * we do not free it here.
133 */
134 return -1;
135 }
136
137 ecn = ip6_frag_ecn(ipv6_hdr(skb));
138
139 if (skb->ip_summed == CHECKSUM_COMPLETE) {
140 const unsigned char *nh = skb_network_header(skb);
141 skb->csum = csum_sub(skb->csum,
142 csum_partial(nh, (u8 *)(fhdr + 1) - nh,
143 0));
144 }
145
146 /* Is this the final fragment? */
147 if (!(fhdr->frag_off & htons(IP6_MF))) {
148 /* If we already have some bits beyond end
149 * or have different end, the segment is corrupted.
150 */
151 if (end < fq->q.len ||
152 ((fq->q.flags & INET_FRAG_LAST_IN) && end != fq->q.len))
153 goto discard_fq;
154 fq->q.flags |= INET_FRAG_LAST_IN;
155 fq->q.len = end;
156 } else {
157 /* Check if the fragment is rounded to 8 bytes.
158 * Required by the RFC.
159 */
160 if (end & 0x7) {
161 /* RFC2460 says always send parameter problem in
162 * this case. -DaveM
163 */
164 *prob_offset = offsetof(struct ipv6hdr, payload_len);
165 return -1;
166 }
167 if (end > fq->q.len) {
168 /* Some bits beyond end -> corruption. */
169 if (fq->q.flags & INET_FRAG_LAST_IN)
170 goto discard_fq;
171 fq->q.len = end;
172 }
173 }
174
175 if (end == offset)
176 goto discard_fq;
177
178 err = -ENOMEM;
179 /* Point into the IP datagram 'data' part. */
180 if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
181 goto discard_fq;
182
183 err = pskb_trim_rcsum(skb, end - offset);
184 if (err)
185 goto discard_fq;
186
187 /* Note : skb->rbnode and skb->dev share the same location. */
188 dev = skb->dev;
189 /* Makes sure compiler wont do silly aliasing games */
190 barrier();
191
192 prev_tail = fq->q.fragments_tail;
193 err = inet_frag_queue_insert(&fq->q, skb, offset, end);
194 if (err)
195 goto insert_error;
196
197 if (dev)
198 fq->iif = dev->ifindex;
199
200 fq->q.stamp = skb->tstamp;
201 fq->q.mono_delivery_time = skb->mono_delivery_time;
202 fq->q.meat += skb->len;
203 fq->ecn |= ecn;
204 add_frag_mem_limit(fq->q.fqdir, skb->truesize);
205
206 fragsize = -skb_network_offset(skb) + skb->len;
207 if (fragsize > fq->q.max_size)
208 fq->q.max_size = fragsize;
209
210 /* The first fragment.
211 * nhoffset is obtained from the first fragment, of course.
212 */
213 if (offset == 0) {
214 fq->nhoffset = nhoff;
215 fq->q.flags |= INET_FRAG_FIRST_IN;
216 }
217
218 if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
219 fq->q.meat == fq->q.len) {
220 unsigned long orefdst = skb->_skb_refdst;
221
222 skb->_skb_refdst = 0UL;
223 err = ip6_frag_reasm(fq, skb, prev_tail, dev);
224 skb->_skb_refdst = orefdst;
225 return err;
226 }
227
228 skb_dst_drop(skb);
229 return -EINPROGRESS;
230
231insert_error:
232 if (err == IPFRAG_DUP) {
233 SKB_DR_SET(reason, DUP_FRAG);
234 err = -EINVAL;
235 goto err;
236 }
237 err = -EINVAL;
238 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
239 IPSTATS_MIB_REASM_OVERLAPS);
240discard_fq:
241 inet_frag_kill(&fq->q);
242 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
243 IPSTATS_MIB_REASMFAILS);
244err:
245 kfree_skb_reason(skb, reason);
246 return err;
247}
248
249/*
250 * Check if this packet is complete.
251 *
252 * It is called with locked fq, and caller must check that
253 * queue is eligible for reassembly i.e. it is not COMPLETE,
254 * the last and the first frames arrived and all the bits are here.
255 */
256static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *skb,
257 struct sk_buff *prev_tail, struct net_device *dev)
258{
259 struct net *net = fq->q.fqdir->net;
260 unsigned int nhoff;
261 void *reasm_data;
262 int payload_len;
263 u8 ecn;
264
265 inet_frag_kill(&fq->q);
266
267 ecn = ip_frag_ecn_table[fq->ecn];
268 if (unlikely(ecn == 0xff))
269 goto out_fail;
270
271 reasm_data = inet_frag_reasm_prepare(&fq->q, skb, prev_tail);
272 if (!reasm_data)
273 goto out_oom;
274
275 payload_len = ((skb->data - skb_network_header(skb)) -
276 sizeof(struct ipv6hdr) + fq->q.len -
277 sizeof(struct frag_hdr));
278 if (payload_len > IPV6_MAXPLEN)
279 goto out_oversize;
280
281 /* We have to remove fragment header from datagram and to relocate
282 * header in order to calculate ICV correctly. */
283 nhoff = fq->nhoffset;
284 skb_network_header(skb)[nhoff] = skb_transport_header(skb)[0];
285 memmove(skb->head + sizeof(struct frag_hdr), skb->head,
286 (skb->data - skb->head) - sizeof(struct frag_hdr));
287 if (skb_mac_header_was_set(skb))
288 skb->mac_header += sizeof(struct frag_hdr);
289 skb->network_header += sizeof(struct frag_hdr);
290
291 skb_reset_transport_header(skb);
292
293 inet_frag_reasm_finish(&fq->q, skb, reasm_data, true);
294
295 skb->dev = dev;
296 ipv6_hdr(skb)->payload_len = htons(payload_len);
297 ipv6_change_dsfield(ipv6_hdr(skb), 0xff, ecn);
298 IP6CB(skb)->nhoff = nhoff;
299 IP6CB(skb)->flags |= IP6SKB_FRAGMENTED;
300 IP6CB(skb)->frag_max_size = fq->q.max_size;
301
302 /* Yes, and fold redundant checksum back. 8) */
303 skb_postpush_rcsum(skb, skb_network_header(skb),
304 skb_network_header_len(skb));
305
306 rcu_read_lock();
307 __IP6_INC_STATS(net, __in6_dev_stats_get(dev, skb), IPSTATS_MIB_REASMOKS);
308 rcu_read_unlock();
309 fq->q.rb_fragments = RB_ROOT;
310 fq->q.fragments_tail = NULL;
311 fq->q.last_run_head = NULL;
312 return 1;
313
314out_oversize:
315 net_dbg_ratelimited("ip6_frag_reasm: payload len = %d\n", payload_len);
316 goto out_fail;
317out_oom:
318 net_dbg_ratelimited("ip6_frag_reasm: no memory for reassembly\n");
319out_fail:
320 rcu_read_lock();
321 __IP6_INC_STATS(net, __in6_dev_stats_get(dev, skb), IPSTATS_MIB_REASMFAILS);
322 rcu_read_unlock();
323 inet_frag_kill(&fq->q);
324 return -1;
325}
326
327static int ipv6_frag_rcv(struct sk_buff *skb)
328{
329 struct frag_hdr *fhdr;
330 struct frag_queue *fq;
331 const struct ipv6hdr *hdr = ipv6_hdr(skb);
332 struct net *net = dev_net(skb_dst(skb)->dev);
333 u8 nexthdr;
334 int iif;
335
336 if (IP6CB(skb)->flags & IP6SKB_FRAGMENTED)
337 goto fail_hdr;
338
339 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMREQDS);
340
341 /* Jumbo payload inhibits frag. header */
342 if (hdr->payload_len == 0)
343 goto fail_hdr;
344
345 if (!pskb_may_pull(skb, (skb_transport_offset(skb) +
346 sizeof(struct frag_hdr))))
347 goto fail_hdr;
348
349 hdr = ipv6_hdr(skb);
350 fhdr = (struct frag_hdr *)skb_transport_header(skb);
351
352 if (!(fhdr->frag_off & htons(IP6_OFFSET | IP6_MF))) {
353 /* It is not a fragmented frame */
354 skb->transport_header += sizeof(struct frag_hdr);
355 __IP6_INC_STATS(net,
356 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMOKS);
357
358 IP6CB(skb)->nhoff = (u8 *)fhdr - skb_network_header(skb);
359 IP6CB(skb)->flags |= IP6SKB_FRAGMENTED;
360 IP6CB(skb)->frag_max_size = ntohs(hdr->payload_len) +
361 sizeof(struct ipv6hdr);
362 return 1;
363 }
364
365 /* RFC 8200, Section 4.5 Fragment Header:
366 * If the first fragment does not include all headers through an
367 * Upper-Layer header, then that fragment should be discarded and
368 * an ICMP Parameter Problem, Code 3, message should be sent to
369 * the source of the fragment, with the Pointer field set to zero.
370 */
371 nexthdr = hdr->nexthdr;
372 if (ipv6frag_thdr_truncated(skb, skb_transport_offset(skb), &nexthdr)) {
373 __IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev),
374 IPSTATS_MIB_INHDRERRORS);
375 icmpv6_param_prob(skb, ICMPV6_HDR_INCOMP, 0);
376 return -1;
377 }
378
379 iif = skb->dev ? skb->dev->ifindex : 0;
380 fq = fq_find(net, fhdr->identification, hdr, iif);
381 if (fq) {
382 u32 prob_offset = 0;
383 int ret;
384
385 spin_lock(&fq->q.lock);
386
387 fq->iif = iif;
388 ret = ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff,
389 &prob_offset);
390
391 spin_unlock(&fq->q.lock);
392 inet_frag_put(&fq->q);
393 if (prob_offset) {
394 __IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev),
395 IPSTATS_MIB_INHDRERRORS);
396 /* icmpv6_param_prob() calls kfree_skb(skb) */
397 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, prob_offset);
398 }
399 return ret;
400 }
401
402 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMFAILS);
403 kfree_skb(skb);
404 return -1;
405
406fail_hdr:
407 __IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev),
408 IPSTATS_MIB_INHDRERRORS);
409 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb_network_header_len(skb));
410 return -1;
411}
412
413static const struct inet6_protocol frag_protocol = {
414 .handler = ipv6_frag_rcv,
415 .flags = INET6_PROTO_NOPOLICY,
416};
417
418#ifdef CONFIG_SYSCTL
419
420static struct ctl_table ip6_frags_ns_ctl_table[] = {
421 {
422 .procname = "ip6frag_high_thresh",
423 .maxlen = sizeof(unsigned long),
424 .mode = 0644,
425 .proc_handler = proc_doulongvec_minmax,
426 },
427 {
428 .procname = "ip6frag_low_thresh",
429 .maxlen = sizeof(unsigned long),
430 .mode = 0644,
431 .proc_handler = proc_doulongvec_minmax,
432 },
433 {
434 .procname = "ip6frag_time",
435 .maxlen = sizeof(int),
436 .mode = 0644,
437 .proc_handler = proc_dointvec_jiffies,
438 },
439 { }
440};
441
442/* secret interval has been deprecated */
443static int ip6_frags_secret_interval_unused;
444static struct ctl_table ip6_frags_ctl_table[] = {
445 {
446 .procname = "ip6frag_secret_interval",
447 .data = &ip6_frags_secret_interval_unused,
448 .maxlen = sizeof(int),
449 .mode = 0644,
450 .proc_handler = proc_dointvec_jiffies,
451 },
452 { }
453};
454
455static int __net_init ip6_frags_ns_sysctl_register(struct net *net)
456{
457 struct ctl_table *table;
458 struct ctl_table_header *hdr;
459
460 table = ip6_frags_ns_ctl_table;
461 if (!net_eq(net, &init_net)) {
462 table = kmemdup(table, sizeof(ip6_frags_ns_ctl_table), GFP_KERNEL);
463 if (!table)
464 goto err_alloc;
465
466 }
467 table[0].data = &net->ipv6.fqdir->high_thresh;
468 table[0].extra1 = &net->ipv6.fqdir->low_thresh;
469 table[1].data = &net->ipv6.fqdir->low_thresh;
470 table[1].extra2 = &net->ipv6.fqdir->high_thresh;
471 table[2].data = &net->ipv6.fqdir->timeout;
472
473 hdr = register_net_sysctl(net, "net/ipv6", table);
474 if (!hdr)
475 goto err_reg;
476
477 net->ipv6.sysctl.frags_hdr = hdr;
478 return 0;
479
480err_reg:
481 if (!net_eq(net, &init_net))
482 kfree(table);
483err_alloc:
484 return -ENOMEM;
485}
486
487static void __net_exit ip6_frags_ns_sysctl_unregister(struct net *net)
488{
489 struct ctl_table *table;
490
491 table = net->ipv6.sysctl.frags_hdr->ctl_table_arg;
492 unregister_net_sysctl_table(net->ipv6.sysctl.frags_hdr);
493 if (!net_eq(net, &init_net))
494 kfree(table);
495}
496
497static struct ctl_table_header *ip6_ctl_header;
498
499static int ip6_frags_sysctl_register(void)
500{
501 ip6_ctl_header = register_net_sysctl(&init_net, "net/ipv6",
502 ip6_frags_ctl_table);
503 return ip6_ctl_header == NULL ? -ENOMEM : 0;
504}
505
506static void ip6_frags_sysctl_unregister(void)
507{
508 unregister_net_sysctl_table(ip6_ctl_header);
509}
510#else
511static int ip6_frags_ns_sysctl_register(struct net *net)
512{
513 return 0;
514}
515
516static void ip6_frags_ns_sysctl_unregister(struct net *net)
517{
518}
519
520static int ip6_frags_sysctl_register(void)
521{
522 return 0;
523}
524
525static void ip6_frags_sysctl_unregister(void)
526{
527}
528#endif
529
530static int __net_init ipv6_frags_init_net(struct net *net)
531{
532 int res;
533
534 res = fqdir_init(&net->ipv6.fqdir, &ip6_frags, net);
535 if (res < 0)
536 return res;
537
538 net->ipv6.fqdir->high_thresh = IPV6_FRAG_HIGH_THRESH;
539 net->ipv6.fqdir->low_thresh = IPV6_FRAG_LOW_THRESH;
540 net->ipv6.fqdir->timeout = IPV6_FRAG_TIMEOUT;
541
542 res = ip6_frags_ns_sysctl_register(net);
543 if (res < 0)
544 fqdir_exit(net->ipv6.fqdir);
545 return res;
546}
547
548static void __net_exit ipv6_frags_pre_exit_net(struct net *net)
549{
550 fqdir_pre_exit(net->ipv6.fqdir);
551}
552
553static void __net_exit ipv6_frags_exit_net(struct net *net)
554{
555 ip6_frags_ns_sysctl_unregister(net);
556 fqdir_exit(net->ipv6.fqdir);
557}
558
559static struct pernet_operations ip6_frags_ops = {
560 .init = ipv6_frags_init_net,
561 .pre_exit = ipv6_frags_pre_exit_net,
562 .exit = ipv6_frags_exit_net,
563};
564
565static const struct rhashtable_params ip6_rhash_params = {
566 .head_offset = offsetof(struct inet_frag_queue, node),
567 .hashfn = ip6frag_key_hashfn,
568 .obj_hashfn = ip6frag_obj_hashfn,
569 .obj_cmpfn = ip6frag_obj_cmpfn,
570 .automatic_shrinking = true,
571};
572
573int __init ipv6_frag_init(void)
574{
575 int ret;
576
577 ip6_frags.constructor = ip6frag_init;
578 ip6_frags.destructor = NULL;
579 ip6_frags.qsize = sizeof(struct frag_queue);
580 ip6_frags.frag_expire = ip6_frag_expire;
581 ip6_frags.frags_cache_name = ip6_frag_cache_name;
582 ip6_frags.rhash_params = ip6_rhash_params;
583 ret = inet_frags_init(&ip6_frags);
584 if (ret)
585 goto out;
586
587 ret = inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT);
588 if (ret)
589 goto err_protocol;
590
591 ret = ip6_frags_sysctl_register();
592 if (ret)
593 goto err_sysctl;
594
595 ret = register_pernet_subsys(&ip6_frags_ops);
596 if (ret)
597 goto err_pernet;
598
599out:
600 return ret;
601
602err_pernet:
603 ip6_frags_sysctl_unregister();
604err_sysctl:
605 inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
606err_protocol:
607 inet_frags_fini(&ip6_frags);
608 goto out;
609}
610
611void ipv6_frag_exit(void)
612{
613 ip6_frags_sysctl_unregister();
614 unregister_pernet_subsys(&ip6_frags_ops);
615 inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
616 inet_frags_fini(&ip6_frags);
617}