net/ipv6/reassembly.c - fp2-dev/kernel/msm - Gitiles

 /*
  *	IPv6 fragment reassembly
  *	Linux INET6 implementation
  *
  *	Authors:
  *	Pedro Roque		<roque@di.fc.ul.pt>
  *
  *	Based on: net/ipv4/ip_fragment.c
  *
  *	This program is free software; you can redistribute it and/or
  *      modify it under the terms of the GNU General Public License
  *      as published by the Free Software Foundation; either version
  *      2 of the License, or (at your option) any later version.
  */

 /*
  *	Fixes:
  *	Andi Kleen	Make it work with multiple hosts.
  *			More RFC compliance.
  *
  *      Horst von Brand Add missing #include <linux/string.h>
  *	Alexey Kuznetsov	SMP races, threading, cleanup.
  *	Patrick McHardy		LRU queue of frag heads for evictor.
  *	Mitsuru KANDA @USAGI	Register inet6_protocol{}.
  *	David Stevens and
  *	YOSHIFUJI,H. @USAGI	Always remove fragment header to
  *				calculate ICV correctly.
  */
 #include <linux/errno.h>
 #include <linux/types.h>
 #include <linux/string.h>
 #include <linux/socket.h>
 #include <linux/sockios.h>
 #include <linux/jiffies.h>
 #include <linux/net.h>
 #include <linux/list.h>
 #include <linux/netdevice.h>
 #include <linux/in6.h>
 #include <linux/ipv6.h>
 #include <linux/icmpv6.h>
 #include <linux/random.h>
 #include <linux/jhash.h>
 #include <linux/skbuff.h>

 #include <net/sock.h>
 #include <net/snmp.h>

 #include <net/ipv6.h>
 #include <net/ip6_route.h>
 #include <net/protocol.h>
 #include <net/transp_v6.h>
 #include <net/rawv6.h>
 #include <net/ndisc.h>
 #include <net/addrconf.h>
 #include <net/inet_frag.h>

 struct ip6frag_skb_cb
 {
 	struct inet6_skb_parm	h;
 	int			offset;
 };

 #define FRAG6_CB(skb)	((struct ip6frag_skb_cb*)((skb)->cb))


 /*
  *	Equivalent of ipv4 struct ipq
  */

 struct frag_queue
 {
 	struct inet_frag_queue	q;

 	__be32			id;		/* fragment id		*/
 	struct in6_addr		saddr;
 	struct in6_addr		daddr;

 	int			iif;
 	unsigned int		csum;
 	__u16			nhoffset;
 };

 static struct inet_frags ip6_frags;

 int ip6_frag_nqueues(struct net *net)
 {
 	return net->ipv6.frags.nqueues;
 }

 int ip6_frag_mem(struct net *net)
 {
 	return atomic_read(&net->ipv6.frags.mem);
 }

 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 			  struct net_device *dev);

 /*
  * callers should be careful not to use the hash value outside the ipfrag_lock
  * as doing so could race with ipfrag_hash_rnd being recalculated.
  */
 unsigned int inet6_hash_frag(__be32 id, const struct in6_addr *saddr,
 			     const struct in6_addr *daddr, u32 rnd)
 {
 	u32 a, b, c;

 	a = (__force u32)saddr->s6_addr32[0];
 	b = (__force u32)saddr->s6_addr32[1];
 	c = (__force u32)saddr->s6_addr32[2];

 	a += JHASH_GOLDEN_RATIO;
 	b += JHASH_GOLDEN_RATIO;
 	c += rnd;
 	__jhash_mix(a, b, c);

 	a += (__force u32)saddr->s6_addr32[3];
 	b += (__force u32)daddr->s6_addr32[0];
 	c += (__force u32)daddr->s6_addr32[1];
 	__jhash_mix(a, b, c);

 	a += (__force u32)daddr->s6_addr32[2];
 	b += (__force u32)daddr->s6_addr32[3];
 	c += (__force u32)id;
 	__jhash_mix(a, b, c);

 	return c & (INETFRAGS_HASHSZ - 1);
 }
 EXPORT_SYMBOL_GPL(inet6_hash_frag);

 static unsigned int ip6_hashfn(struct inet_frag_queue *q)
 {
 	struct frag_queue *fq;

 	fq = container_of(q, struct frag_queue, q);
 	return inet6_hash_frag(fq->id, &fq->saddr, &fq->daddr, ip6_frags.rnd);
 }

 int ip6_frag_match(struct inet_frag_queue *q, void *a)
 {
 	struct frag_queue *fq;
 	struct ip6_create_arg *arg = a;

 	fq = container_of(q, struct frag_queue, q);
 	return (fq->id == arg->id &&
 			ipv6_addr_equal(&fq->saddr, arg->src) &&
 			ipv6_addr_equal(&fq->daddr, arg->dst));
 }
 EXPORT_SYMBOL(ip6_frag_match);

 /* Memory Tracking Functions. */
 static inline void frag_kfree_skb(struct netns_frags *nf,
 		struct sk_buff *skb, int *work)
 {
 	if (work)
 		*work -= skb->truesize;
 	atomic_sub(skb->truesize, &nf->mem);
 	kfree_skb(skb);
 }

 void ip6_frag_init(struct inet_frag_queue *q, void *a)
 {
 	struct frag_queue *fq = container_of(q, struct frag_queue, q);
 	struct ip6_create_arg *arg = a;

 	fq->id = arg->id;
 	ipv6_addr_copy(&fq->saddr, arg->src);
 	ipv6_addr_copy(&fq->daddr, arg->dst);
 }
 EXPORT_SYMBOL(ip6_frag_init);

 /* Destruction primitives. */

 static __inline__ void fq_put(struct frag_queue *fq)
 {
 	inet_frag_put(&fq->q, &ip6_frags);
 }

 /* Kill fq entry. It is not destroyed immediately,
  * because caller (and someone more) holds reference count.
  */
 static __inline__ void fq_kill(struct frag_queue *fq)
 {
 	inet_frag_kill(&fq->q, &ip6_frags);
 }

 static void ip6_evictor(struct net *net, struct inet6_dev *idev)
 {
 	int evicted;

 	evicted = inet_frag_evictor(&net->ipv6.frags, &ip6_frags);
 	if (evicted)
 		IP6_ADD_STATS_BH(net, idev, IPSTATS_MIB_REASMFAILS, evicted);
 }

 static void ip6_frag_expire(unsigned long data)
 {
 	struct frag_queue *fq;
 	struct net_device *dev = NULL;
 	struct net *net;

 	fq = container_of((struct inet_frag_queue *)data, struct frag_queue, q);

 	spin_lock(&fq->q.lock);

 	if (fq->q.last_in & INET_FRAG_COMPLETE)
 		goto out;

 	fq_kill(fq);

 	net = container_of(fq->q.net, struct net, ipv6.frags);
 	dev = dev_get_by_index(net, fq->iif);
 	if (!dev)
 		goto out;

 	rcu_read_lock();
 	IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMTIMEOUT);
 	IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
 	rcu_read_unlock();

 	/* Don't send error if the first segment did not arrive. */
 	if (!(fq->q.last_in & INET_FRAG_FIRST_IN) || !fq->q.fragments)
 		goto out;

 	/*
 	   But use as source device on which LAST ARRIVED
 	   segment was received. And do not use fq->dev
 	   pointer directly, device might already disappeared.
 	 */
 	fq->q.fragments->dev = dev;
 	icmpv6_send(fq->q.fragments, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0, dev);
 out:
 	if (dev)
 		dev_put(dev);
 	spin_unlock(&fq->q.lock);
 	fq_put(fq);
 }

 static __inline__ struct frag_queue *
 fq_find(struct net *net, __be32 id, struct in6_addr *src, struct in6_addr *dst,
 	struct inet6_dev *idev)
 {
 	struct inet_frag_queue *q;
 	struct ip6_create_arg arg;
 	unsigned int hash;

 	arg.id = id;
 	arg.src = src;
 	arg.dst = dst;

 	read_lock(&ip6_frags.lock);
 	hash = inet6_hash_frag(id, src, dst, ip6_frags.rnd);

 	q = inet_frag_find(&net->ipv6.frags, &ip6_frags, &arg, hash);
 	if (q == NULL)
 		goto oom;

 	return container_of(q, struct frag_queue, q);

 oom:
 	IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_REASMFAILS);
 	return NULL;
 }

 static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 			   struct frag_hdr *fhdr, int nhoff)
 {
 	struct sk_buff *prev, *next;
 	struct net_device *dev;
 	int offset, end;
 	struct net *net = dev_net(skb_dst(skb)->dev);

 	if (fq->q.last_in & INET_FRAG_COMPLETE)
 		goto err;

 	offset = ntohs(fhdr->frag_off) & ~0x7;
 	end = offset + (ntohs(ipv6_hdr(skb)->payload_len) -
 			((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1)));

 	if ((unsigned int)end > IPV6_MAXPLEN) {
 		IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 				 IPSTATS_MIB_INHDRERRORS);
 		icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 				  ((u8 *)&fhdr->frag_off -
 				   skb_network_header(skb)));
 		return -1;
 	}

 	if (skb->ip_summed == CHECKSUM_COMPLETE) {
 		const unsigned char *nh = skb_network_header(skb);
 		skb->csum = csum_sub(skb->csum,
 				     csum_partial(nh, (u8 *)(fhdr + 1) - nh,
 						  0));
 	}

 	/* Is this the final fragment? */
 	if (!(fhdr->frag_off & htons(IP6_MF))) {
 		/* If we already have some bits beyond end
 		 * or have different end, the segment is corrupted.
 		 */
 		if (end < fq->q.len ||
 		    ((fq->q.last_in & INET_FRAG_LAST_IN) && end != fq->q.len))
 			goto err;
 		fq->q.last_in |= INET_FRAG_LAST_IN;
 		fq->q.len = end;
 	} else {
 		/* Check if the fragment is rounded to 8 bytes.
 		 * Required by the RFC.
 		 */
 		if (end & 0x7) {
 			/* RFC2460 says always send parameter problem in
 			 * this case. -DaveM
 			 */
 			IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
 					 IPSTATS_MIB_INHDRERRORS);
 			icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
 					  offsetof(struct ipv6hdr, payload_len));
 			return -1;
 		}
 		if (end > fq->q.len) {
 			/* Some bits beyond end -> corruption. */
 			if (fq->q.last_in & INET_FRAG_LAST_IN)
 				goto err;
 			fq->q.len = end;
 		}
 	}

 	if (end == offset)
 		goto err;

 	/* Point into the IP datagram 'data' part. */
 	if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
 		goto err;

 	if (pskb_trim_rcsum(skb, end - offset))
 		goto err;

 	/* Find out which fragments are in front and at the back of us
 	 * in the chain of fragments so far.  We must know where to put
 	 * this fragment, right?
 	 */
 	prev = NULL;
 	for(next = fq->q.fragments; next != NULL; next = next->next) {
 		if (FRAG6_CB(next)->offset >= offset)
 			break;	/* bingo! */
 		prev = next;
 	}

 	/* We found where to put this one.  Check for overlap with
 	 * preceding fragment, and, if needed, align things so that
 	 * any overlaps are eliminated.
 	 */
 	if (prev) {
 		int i = (FRAG6_CB(prev)->offset + prev->len) - offset;

 		if (i > 0) {
 			offset += i;
 			if (end <= offset)
 				goto err;
 			if (!pskb_pull(skb, i))
 				goto err;
 			if (skb->ip_summed != CHECKSUM_UNNECESSARY)
 				skb->ip_summed = CHECKSUM_NONE;
 		}
 	}

 	/* Look for overlap with succeeding segments.
 	 * If we can merge fragments, do it.
 	 */
 	while (next && FRAG6_CB(next)->offset < end) {
 		int i = end - FRAG6_CB(next)->offset; /* overlap is 'i' bytes */

 		if (i < next->len) {
 			/* Eat head of the next overlapped fragment
 			 * and leave the loop. The next ones cannot overlap.
 			 */
 			if (!pskb_pull(next, i))
 				goto err;
 			FRAG6_CB(next)->offset += i;	/* next fragment */
 			fq->q.meat -= i;
 			if (next->ip_summed != CHECKSUM_UNNECESSARY)
 				next->ip_summed = CHECKSUM_NONE;
 			break;
 		} else {
 			struct sk_buff *free_it = next;

 			/* Old fragment is completely overridden with
 			 * new one drop it.
 			 */
 			next = next->next;

 			if (prev)
 				prev->next = next;
 			else
 				fq->q.fragments = next;

 			fq->q.meat -= free_it->len;
 			frag_kfree_skb(fq->q.net, free_it, NULL);
 		}
 	}

 	FRAG6_CB(skb)->offset = offset;

 	/* Insert this fragment in the chain of fragments. */
 	skb->next = next;
 	if (prev)
 		prev->next = skb;
 	else
 		fq->q.fragments = skb;

 	dev = skb->dev;
 	if (dev) {
 		fq->iif = dev->ifindex;
 		skb->dev = NULL;
 	}
 	fq->q.stamp = skb->tstamp;
 	fq->q.meat += skb->len;
 	atomic_add(skb->truesize, &fq->q.net->mem);

 	/* The first fragment.
 	 * nhoffset is obtained from the first fragment, of course.
 	 */
 	if (offset == 0) {
 		fq->nhoffset = nhoff;
 		fq->q.last_in |= INET_FRAG_FIRST_IN;
 	}

 	if (fq->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
 	    fq->q.meat == fq->q.len)
 		return ip6_frag_reasm(fq, prev, dev);

 	write_lock(&ip6_frags.lock);
 	list_move_tail(&fq->q.lru_list, &fq->q.net->lru_list);
 	write_unlock(&ip6_frags.lock);
 	return -1;

 err:
 	IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 		      IPSTATS_MIB_REASMFAILS);
 	kfree_skb(skb);
 	return -1;
 }

 /*
  *	Check if this packet is complete.
  *	Returns NULL on failure by any reason, and pointer
  *	to current nexthdr field in reassembled frame.
  *
  *	It is called with locked fq, and caller must check that
  *	queue is eligible for reassembly i.e. it is not COMPLETE,
  *	the last and the first frames arrived and all the bits are here.
  */
 static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 			  struct net_device *dev)
 {
 	struct net *net = container_of(fq->q.net, struct net, ipv6.frags);
 	struct sk_buff *fp, *head = fq->q.fragments;
 	int    payload_len;
 	unsigned int nhoff;

 	fq_kill(fq);

 	/* Make the one we just received the head. */
 	if (prev) {
 		head = prev->next;
 		fp = skb_clone(head, GFP_ATOMIC);

 		if (!fp)
 			goto out_oom;

 		fp->next = head->next;
 		prev->next = fp;

 		skb_morph(head, fq->q.fragments);
 		head->next = fq->q.fragments->next;

 		kfree_skb(fq->q.fragments);
 		fq->q.fragments = head;
 	}

 	WARN_ON(head == NULL);
 	WARN_ON(FRAG6_CB(head)->offset != 0);

 	/* Unfragmented part is taken from the first segment. */
 	payload_len = ((head->data - skb_network_header(head)) -
 		       sizeof(struct ipv6hdr) + fq->q.len -
 		       sizeof(struct frag_hdr));
 	if (payload_len > IPV6_MAXPLEN)
 		goto out_oversize;

 	/* Head of list must not be cloned. */
 	if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
 		goto out_oom;

 	/* If the first fragment is fragmented itself, we split
 	 * it to two chunks: the first with data and paged part
 	 * and the second, holding only fragments. */
 	if (skb_has_frags(head)) {
 		struct sk_buff *clone;
 		int i, plen = 0;

 		if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
 			goto out_oom;
 		clone->next = head->next;
 		head->next = clone;
 		skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
 		skb_frag_list_init(head);
 		for (i=0; i<skb_shinfo(head)->nr_frags; i++)
 			plen += skb_shinfo(head)->frags[i].size;
 		clone->len = clone->data_len = head->data_len - plen;
 		head->data_len -= clone->len;
 		head->len -= clone->len;
 		clone->csum = 0;
 		clone->ip_summed = head->ip_summed;
 		atomic_add(clone->truesize, &fq->q.net->mem);
 	}

 	/* We have to remove fragment header from datagram and to relocate
 	 * header in order to calculate ICV correctly. */
 	nhoff = fq->nhoffset;
 	skb_network_header(head)[nhoff] = skb_transport_header(head)[0];
 	memmove(head->head + sizeof(struct frag_hdr), head->head,
 		(head->data - head->head) - sizeof(struct frag_hdr));
 	head->mac_header += sizeof(struct frag_hdr);
 	head->network_header += sizeof(struct frag_hdr);

 	skb_shinfo(head)->frag_list = head->next;
 	skb_reset_transport_header(head);
 	skb_push(head, head->data - skb_network_header(head));
 	atomic_sub(head->truesize, &fq->q.net->mem);

 	for (fp=head->next; fp; fp = fp->next) {
 		head->data_len += fp->len;
 		head->len += fp->len;
 		if (head->ip_summed != fp->ip_summed)
 			head->ip_summed = CHECKSUM_NONE;
 		else if (head->ip_summed == CHECKSUM_COMPLETE)
 			head->csum = csum_add(head->csum, fp->csum);
 		head->truesize += fp->truesize;
 		atomic_sub(fp->truesize, &fq->q.net->mem);
 	}

 	head->next = NULL;
 	head->dev = dev;
 	head->tstamp = fq->q.stamp;
 	ipv6_hdr(head)->payload_len = htons(payload_len);
 	IP6CB(head)->nhoff = nhoff;

 	/* Yes, and fold redundant checksum back. 8) */
 	if (head->ip_summed == CHECKSUM_COMPLETE)
 		head->csum = csum_partial(skb_network_header(head),
 					  skb_network_header_len(head),
 					  head->csum);

 	rcu_read_lock();
 	IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
 	rcu_read_unlock();
 	fq->q.fragments = NULL;
 	return 1;

 out_oversize:
 	if (net_ratelimit())
 		printk(KERN_DEBUG "ip6_frag_reasm: payload len = %d\n", payload_len);
 	goto out_fail;
 out_oom:
 	if (net_ratelimit())
 		printk(KERN_DEBUG "ip6_frag_reasm: no memory for reassembly\n");
 out_fail:
 	rcu_read_lock();
 	IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
 	rcu_read_unlock();
 	return -1;
 }

 static int ipv6_frag_rcv(struct sk_buff *skb)
 {
 	struct frag_hdr *fhdr;
 	struct frag_queue *fq;
 	struct ipv6hdr *hdr = ipv6_hdr(skb);
 	struct net *net = dev_net(skb_dst(skb)->dev);

 	IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMREQDS);

 	/* Jumbo payload inhibits frag. header */
 	if (hdr->payload_len==0)
 		goto fail_hdr;

 	if (!pskb_may_pull(skb, (skb_transport_offset(skb) +
 				 sizeof(struct frag_hdr))))
 		goto fail_hdr;

 	hdr = ipv6_hdr(skb);
 	fhdr = (struct frag_hdr *)skb_transport_header(skb);

 	if (!(fhdr->frag_off & htons(0xFFF9))) {
 		/* It is not a fragmented frame */
 		skb->transport_header += sizeof(struct frag_hdr);
 		IP6_INC_STATS_BH(net,
 				 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMOKS);

 		IP6CB(skb)->nhoff = (u8 *)fhdr - skb_network_header(skb);
 		return 1;
 	}

 	if (atomic_read(&net->ipv6.frags.mem) > net->ipv6.frags.high_thresh)
 		ip6_evictor(net, ip6_dst_idev(skb_dst(skb)));

 	if ((fq = fq_find(net, fhdr->identification, &hdr->saddr, &hdr->daddr,
 			  ip6_dst_idev(skb_dst(skb)))) != NULL) {
 		int ret;

 		spin_lock(&fq->q.lock);

 		ret = ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff);

 		spin_unlock(&fq->q.lock);
 		fq_put(fq);
 		return ret;
 	}

 	IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMFAILS);
 	kfree_skb(skb);
 	return -1;

 fail_hdr:
 	IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS);
 	icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb_network_header_len(skb));
 	return -1;
 }

 static const struct inet6_protocol frag_protocol =
 {
 	.handler	=	ipv6_frag_rcv,
 	.flags		=	INET6_PROTO_NOPOLICY,
 };

 #ifdef CONFIG_SYSCTL
 static struct ctl_table ip6_frags_ns_ctl_table[] = {
 	{
 		.ctl_name	= NET_IPV6_IP6FRAG_HIGH_THRESH,
 		.procname	= "ip6frag_high_thresh",
 		.data		= &init_net.ipv6.frags.high_thresh,
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
 	{
 		.ctl_name	= NET_IPV6_IP6FRAG_LOW_THRESH,
 		.procname	= "ip6frag_low_thresh",
 		.data		= &init_net.ipv6.frags.low_thresh,
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
 	{
 		.ctl_name	= NET_IPV6_IP6FRAG_TIME,
 		.procname	= "ip6frag_time",
 		.data		= &init_net.ipv6.frags.timeout,
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
 		.strategy	= sysctl_jiffies,
 	},
 	{ }
 };

 static struct ctl_table ip6_frags_ctl_table[] = {
 	{
 		.ctl_name	= NET_IPV6_IP6FRAG_SECRET_INTERVAL,
 		.procname	= "ip6frag_secret_interval",
 		.data		= &ip6_frags.secret_interval,
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
 		.strategy	= sysctl_jiffies
 	},
 	{ }
 };

 static int ip6_frags_ns_sysctl_register(struct net *net)
 {
 	struct ctl_table *table;
 	struct ctl_table_header *hdr;

 	table = ip6_frags_ns_ctl_table;
 	if (net != &init_net) {
 		table = kmemdup(table, sizeof(ip6_frags_ns_ctl_table), GFP_KERNEL);
 		if (table == NULL)
 			goto err_alloc;

 		table[0].data = &net->ipv6.frags.high_thresh;
 		table[1].data = &net->ipv6.frags.low_thresh;
 		table[2].data = &net->ipv6.frags.timeout;
 	}

 	hdr = register_net_sysctl_table(net, net_ipv6_ctl_path, table);
 	if (hdr == NULL)
 		goto err_reg;

 	net->ipv6.sysctl.frags_hdr = hdr;
 	return 0;

 err_reg:
 	if (net != &init_net)
 		kfree(table);
 err_alloc:
 	return -ENOMEM;
 }

 static void ip6_frags_ns_sysctl_unregister(struct net *net)
 {
 	struct ctl_table *table;

 	table = net->ipv6.sysctl.frags_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(net->ipv6.sysctl.frags_hdr);
 	kfree(table);
 }

 static struct ctl_table_header *ip6_ctl_header;

 static int ip6_frags_sysctl_register(void)
 {
 	ip6_ctl_header = register_net_sysctl_rotable(net_ipv6_ctl_path,
 			ip6_frags_ctl_table);
 	return ip6_ctl_header == NULL ? -ENOMEM : 0;
 }

 static void ip6_frags_sysctl_unregister(void)
 {
 	unregister_net_sysctl_table(ip6_ctl_header);
 }
 #else
 static inline int ip6_frags_ns_sysctl_register(struct net *net)
 {
 	return 0;
 }

 static inline void ip6_frags_ns_sysctl_unregister(struct net *net)
 {
 }

 static inline int ip6_frags_sysctl_register(void)
 {
 	return 0;
 }

 static inline void ip6_frags_sysctl_unregister(void)
 {
 }
 #endif

 static int ipv6_frags_init_net(struct net *net)
 {
 	net->ipv6.frags.high_thresh = 256 * 1024;
 	net->ipv6.frags.low_thresh = 192 * 1024;
 	net->ipv6.frags.timeout = IPV6_FRAG_TIMEOUT;

 	inet_frags_init_net(&net->ipv6.frags);

 	return ip6_frags_ns_sysctl_register(net);
 }

 static void ipv6_frags_exit_net(struct net *net)
 {
 	ip6_frags_ns_sysctl_unregister(net);
 	inet_frags_exit_net(&net->ipv6.frags, &ip6_frags);
 }

 static struct pernet_operations ip6_frags_ops = {
 	.init = ipv6_frags_init_net,
 	.exit = ipv6_frags_exit_net,
 };

 int __init ipv6_frag_init(void)
 {
 	int ret;

 	ret = inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT);
 	if (ret)
 		goto out;

 	ret = ip6_frags_sysctl_register();
 	if (ret)
 		goto err_sysctl;

 	ret = register_pernet_subsys(&ip6_frags_ops);
 	if (ret)
 		goto err_pernet;

 	ip6_frags.hashfn = ip6_hashfn;
 	ip6_frags.constructor = ip6_frag_init;
 	ip6_frags.destructor = NULL;
 	ip6_frags.skb_free = NULL;
 	ip6_frags.qsize = sizeof(struct frag_queue);
 	ip6_frags.match = ip6_frag_match;
 	ip6_frags.frag_expire = ip6_frag_expire;
 	ip6_frags.secret_interval = 10 * 60 * HZ;
 	inet_frags_init(&ip6_frags);
 out:
 	return ret;

 err_pernet:
 	ip6_frags_sysctl_unregister();
 err_sysctl:
 	inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
 	goto out;
 }

 void ipv6_frag_exit(void)
 {
 	inet_frags_fini(&ip6_frags);
 	ip6_frags_sysctl_unregister();
 	unregister_pernet_subsys(&ip6_frags_ops);
 	inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
 }
	/*
	* IPv6 fragment reassembly
	* Linux INET6 implementation
	*
	* Authors:
	* Pedro Roque <roque@di.fc.ul.pt>
	*
	* Based on: net/ipv4/ip_fragment.c
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version
	* 2 of the License, or (at your option) any later version.
	*/

	/*
	* Fixes:
	* Andi Kleen Make it work with multiple hosts.
	* More RFC compliance.
	*
	* Horst von Brand Add missing #include <linux/string.h>
	* Alexey Kuznetsov SMP races, threading, cleanup.
	* Patrick McHardy LRU queue of frag heads for evictor.
	* Mitsuru KANDA @USAGI Register inet6_protocol{}.
	* David Stevens and
	* YOSHIFUJI,H. @USAGI Always remove fragment header to
	* calculate ICV correctly.
	*/
	#include <linux/errno.h>
	#include <linux/types.h>
	#include <linux/string.h>
	#include <linux/socket.h>
	#include <linux/sockios.h>
	#include <linux/jiffies.h>
	#include <linux/net.h>
	#include <linux/list.h>
	#include <linux/netdevice.h>
	#include <linux/in6.h>
	#include <linux/ipv6.h>
	#include <linux/icmpv6.h>
	#include <linux/random.h>
	#include <linux/jhash.h>
	#include <linux/skbuff.h>

	#include <net/sock.h>
	#include <net/snmp.h>

	#include <net/ipv6.h>
	#include <net/ip6_route.h>
	#include <net/protocol.h>
	#include <net/transp_v6.h>
	#include <net/rawv6.h>
	#include <net/ndisc.h>
	#include <net/addrconf.h>
	#include <net/inet_frag.h>

	struct ip6frag_skb_cb
	{
	struct inet6_skb_parm h;
	int offset;
	};

	#define FRAG6_CB(skb) ((struct ip6frag_skb_cb*)((skb)->cb))


	/*
	* Equivalent of ipv4 struct ipq
	*/

	struct frag_queue
	{
	struct inet_frag_queue q;

	__be32 id; /* fragment id */
	struct in6_addr saddr;
	struct in6_addr daddr;

	int iif;
	unsigned int csum;
	__u16 nhoffset;
	};

	static struct inet_frags ip6_frags;

	int ip6_frag_nqueues(struct net *net)
	{
	return net->ipv6.frags.nqueues;
	}

	int ip6_frag_mem(struct net *net)
	{
	return atomic_read(&net->ipv6.frags.mem);
	}

	static int ip6_frag_reasm(struct frag_queue fq, struct sk_buff prev,
	struct net_device *dev);

	/*
	* callers should be careful not to use the hash value outside the ipfrag_lock
	* as doing so could race with ipfrag_hash_rnd being recalculated.
	*/
	unsigned int inet6_hash_frag(__be32 id, const struct in6_addr *saddr,
	const struct in6_addr *daddr, u32 rnd)
	{
	u32 a, b, c;

	a = (__force u32)saddr->s6_addr32[0];
	b = (__force u32)saddr->s6_addr32[1];
	c = (__force u32)saddr->s6_addr32[2];

	a += JHASH_GOLDEN_RATIO;
	b += JHASH_GOLDEN_RATIO;
	c += rnd;
	__jhash_mix(a, b, c);

	a += (__force u32)saddr->s6_addr32[3];
	b += (__force u32)daddr->s6_addr32[0];
	c += (__force u32)daddr->s6_addr32[1];
	__jhash_mix(a, b, c);

	a += (__force u32)daddr->s6_addr32[2];
	b += (__force u32)daddr->s6_addr32[3];
	c += (__force u32)id;
	__jhash_mix(a, b, c);

	return c & (INETFRAGS_HASHSZ - 1);
	}
	EXPORT_SYMBOL_GPL(inet6_hash_frag);

	static unsigned int ip6_hashfn(struct inet_frag_queue *q)
	{
	struct frag_queue *fq;

	fq = container_of(q, struct frag_queue, q);
	return inet6_hash_frag(fq->id, &fq->saddr, &fq->daddr, ip6_frags.rnd);
	}

	int ip6_frag_match(struct inet_frag_queue q, void a)
	{
	struct frag_queue *fq;
	struct ip6_create_arg *arg = a;

	fq = container_of(q, struct frag_queue, q);
	return (fq->id == arg->id &&
	ipv6_addr_equal(&fq->saddr, arg->src) &&
	ipv6_addr_equal(&fq->daddr, arg->dst));
	}
	EXPORT_SYMBOL(ip6_frag_match);

	/* Memory Tracking Functions. */
	static inline void frag_kfree_skb(struct netns_frags *nf,
	struct sk_buff skb, int work)
	{
	if (work)
	*work -= skb->truesize;
	atomic_sub(skb->truesize, &nf->mem);
	kfree_skb(skb);
	}

	void ip6_frag_init(struct inet_frag_queue q, void a)
	{
	struct frag_queue *fq = container_of(q, struct frag_queue, q);
	struct ip6_create_arg *arg = a;

	fq->id = arg->id;
	ipv6_addr_copy(&fq->saddr, arg->src);
	ipv6_addr_copy(&fq->daddr, arg->dst);
	}
	EXPORT_SYMBOL(ip6_frag_init);

	/* Destruction primitives. */

	static __inline__ void fq_put(struct frag_queue *fq)
	{
	inet_frag_put(&fq->q, &ip6_frags);
	}

	/* Kill fq entry. It is not destroyed immediately,
	* because caller (and someone more) holds reference count.
	*/
	static __inline__ void fq_kill(struct frag_queue *fq)
	{
	inet_frag_kill(&fq->q, &ip6_frags);
	}

	static void ip6_evictor(struct net net, struct inet6_dev idev)
	{
	int evicted;

	evicted = inet_frag_evictor(&net->ipv6.frags, &ip6_frags);
	if (evicted)
	IP6_ADD_STATS_BH(net, idev, IPSTATS_MIB_REASMFAILS, evicted);
	}

	static void ip6_frag_expire(unsigned long data)
	{
	struct frag_queue *fq;
	struct net_device *dev = NULL;
	struct net *net;

	fq = container_of((struct inet_frag_queue *)data, struct frag_queue, q);

	spin_lock(&fq->q.lock);

	if (fq->q.last_in & INET_FRAG_COMPLETE)
	goto out;

	fq_kill(fq);

	net = container_of(fq->q.net, struct net, ipv6.frags);
	dev = dev_get_by_index(net, fq->iif);
	if (!dev)
	goto out;

	rcu_read_lock();
	IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMTIMEOUT);
	IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
	rcu_read_unlock();

	/* Don't send error if the first segment did not arrive. */
	if (!(fq->q.last_in & INET_FRAG_FIRST_IN) \|\| !fq->q.fragments)
	goto out;

	/*
	But use as source device on which LAST ARRIVED
	segment was received. And do not use fq->dev
	pointer directly, device might already disappeared.
	*/
	fq->q.fragments->dev = dev;
	icmpv6_send(fq->q.fragments, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0, dev);
	out:
	if (dev)
	dev_put(dev);
	spin_unlock(&fq->q.lock);
	fq_put(fq);
	}

	static __inline__ struct frag_queue *
	fq_find(struct net net, __be32 id, struct in6_addr src, struct in6_addr *dst,
	struct inet6_dev *idev)
	{
	struct inet_frag_queue *q;
	struct ip6_create_arg arg;
	unsigned int hash;

	arg.id = id;
	arg.src = src;
	arg.dst = dst;

	read_lock(&ip6_frags.lock);
	hash = inet6_hash_frag(id, src, dst, ip6_frags.rnd);

	q = inet_frag_find(&net->ipv6.frags, &ip6_frags, &arg, hash);
	if (q == NULL)
	goto oom;

	return container_of(q, struct frag_queue, q);

	oom:
	IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_REASMFAILS);
	return NULL;
	}

	static int ip6_frag_queue(struct frag_queue fq, struct sk_buff skb,
	struct frag_hdr *fhdr, int nhoff)
	{
	struct sk_buff prev, next;
	struct net_device *dev;
	int offset, end;
	struct net *net = dev_net(skb_dst(skb)->dev);

	if (fq->q.last_in & INET_FRAG_COMPLETE)
	goto err;

	offset = ntohs(fhdr->frag_off) & ~0x7;
	end = offset + (ntohs(ipv6_hdr(skb)->payload_len) -
	((u8 )(fhdr + 1) - (u8 )(ipv6_hdr(skb) + 1)));

	if ((unsigned int)end > IPV6_MAXPLEN) {
	IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
	IPSTATS_MIB_INHDRERRORS);
	icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
	((u8 *)&fhdr->frag_off -
	skb_network_header(skb)));
	return -1;
	}

	if (skb->ip_summed == CHECKSUM_COMPLETE) {
	const unsigned char *nh = skb_network_header(skb);
	skb->csum = csum_sub(skb->csum,
	csum_partial(nh, (u8 *)(fhdr + 1) - nh,
	0));
	}

	/* Is this the final fragment? */
	if (!(fhdr->frag_off & htons(IP6_MF))) {
	/* If we already have some bits beyond end
	* or have different end, the segment is corrupted.
	*/
	if (end < fq->q.len \|\|
	((fq->q.last_in & INET_FRAG_LAST_IN) && end != fq->q.len))
	goto err;
	fq->q.last_in \|= INET_FRAG_LAST_IN;
	fq->q.len = end;
	} else {
	/* Check if the fragment is rounded to 8 bytes.
	* Required by the RFC.
	*/
	if (end & 0x7) {
	/* RFC2460 says always send parameter problem in
	* this case. -DaveM
	*/
	IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
	IPSTATS_MIB_INHDRERRORS);
	icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
	offsetof(struct ipv6hdr, payload_len));
	return -1;
	}
	if (end > fq->q.len) {
	/* Some bits beyond end -> corruption. */
	if (fq->q.last_in & INET_FRAG_LAST_IN)
	goto err;
	fq->q.len = end;
	}
	}

	if (end == offset)
	goto err;

	/* Point into the IP datagram 'data' part. */
	if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
	goto err;

	if (pskb_trim_rcsum(skb, end - offset))
	goto err;

	/* Find out which fragments are in front and at the back of us
	* in the chain of fragments so far. We must know where to put
	* this fragment, right?
	*/
	prev = NULL;
	for(next = fq->q.fragments; next != NULL; next = next->next) {
	if (FRAG6_CB(next)->offset >= offset)
	break; /* bingo! */
	prev = next;
	}

	/* We found where to put this one. Check for overlap with
	* preceding fragment, and, if needed, align things so that
	* any overlaps are eliminated.
	*/
	if (prev) {
	int i = (FRAG6_CB(prev)->offset + prev->len) - offset;

	if (i > 0) {
	offset += i;
	if (end <= offset)
	goto err;
	if (!pskb_pull(skb, i))
	goto err;
	if (skb->ip_summed != CHECKSUM_UNNECESSARY)
	skb->ip_summed = CHECKSUM_NONE;
	}
	}

	/* Look for overlap with succeeding segments.
	* If we can merge fragments, do it.
	*/
	while (next && FRAG6_CB(next)->offset < end) {
	int i = end - FRAG6_CB(next)->offset; /* overlap is 'i' bytes */

	if (i < next->len) {
	/* Eat head of the next overlapped fragment
	* and leave the loop. The next ones cannot overlap.
	*/
	if (!pskb_pull(next, i))
	goto err;
	FRAG6_CB(next)->offset += i; /* next fragment */
	fq->q.meat -= i;
	if (next->ip_summed != CHECKSUM_UNNECESSARY)
	next->ip_summed = CHECKSUM_NONE;
	break;
	} else {
	struct sk_buff *free_it = next;

	/* Old fragment is completely overridden with
	* new one drop it.
	*/
	next = next->next;

	if (prev)
	prev->next = next;
	else
	fq->q.fragments = next;

	fq->q.meat -= free_it->len;
	frag_kfree_skb(fq->q.net, free_it, NULL);
	}
	}

	FRAG6_CB(skb)->offset = offset;

	/* Insert this fragment in the chain of fragments. */
	skb->next = next;
	if (prev)
	prev->next = skb;
	else
	fq->q.fragments = skb;

	dev = skb->dev;
	if (dev) {
	fq->iif = dev->ifindex;
	skb->dev = NULL;
	}
	fq->q.stamp = skb->tstamp;
	fq->q.meat += skb->len;
	atomic_add(skb->truesize, &fq->q.net->mem);

	/* The first fragment.
	* nhoffset is obtained from the first fragment, of course.
	*/
	if (offset == 0) {
	fq->nhoffset = nhoff;
	fq->q.last_in \|= INET_FRAG_FIRST_IN;
	}

	if (fq->q.last_in == (INET_FRAG_FIRST_IN \| INET_FRAG_LAST_IN) &&
	fq->q.meat == fq->q.len)
	return ip6_frag_reasm(fq, prev, dev);

	write_lock(&ip6_frags.lock);
	list_move_tail(&fq->q.lru_list, &fq->q.net->lru_list);
	write_unlock(&ip6_frags.lock);
	return -1;

	err:
	IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
	IPSTATS_MIB_REASMFAILS);
	kfree_skb(skb);
	return -1;
	}

	/*
	* Check if this packet is complete.
	* Returns NULL on failure by any reason, and pointer
	* to current nexthdr field in reassembled frame.
	*
	* It is called with locked fq, and caller must check that
	* queue is eligible for reassembly i.e. it is not COMPLETE,
	* the last and the first frames arrived and all the bits are here.
	*/
	static int ip6_frag_reasm(struct frag_queue fq, struct sk_buff prev,
	struct net_device *dev)
	{
	struct net *net = container_of(fq->q.net, struct net, ipv6.frags);
	struct sk_buff fp, head = fq->q.fragments;
	int payload_len;
	unsigned int nhoff;

	fq_kill(fq);

	/* Make the one we just received the head. */
	if (prev) {
	head = prev->next;
	fp = skb_clone(head, GFP_ATOMIC);

	if (!fp)
	goto out_oom;

	fp->next = head->next;
	prev->next = fp;

	skb_morph(head, fq->q.fragments);
	head->next = fq->q.fragments->next;

	kfree_skb(fq->q.fragments);
	fq->q.fragments = head;
	}

	WARN_ON(head == NULL);
	WARN_ON(FRAG6_CB(head)->offset != 0);

	/* Unfragmented part is taken from the first segment. */
	payload_len = ((head->data - skb_network_header(head)) -
	sizeof(struct ipv6hdr) + fq->q.len -
	sizeof(struct frag_hdr));
	if (payload_len > IPV6_MAXPLEN)
	goto out_oversize;

	/* Head of list must not be cloned. */
	if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC))
	goto out_oom;

	/* If the first fragment is fragmented itself, we split
	* it to two chunks: the first with data and paged part
	* and the second, holding only fragments. */
	if (skb_has_frags(head)) {
	struct sk_buff *clone;
	int i, plen = 0;

	if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
	goto out_oom;
	clone->next = head->next;
	head->next = clone;
	skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
	skb_frag_list_init(head);
	for (i=0; i<skb_shinfo(head)->nr_frags; i++)
	plen += skb_shinfo(head)->frags[i].size;
	clone->len = clone->data_len = head->data_len - plen;
	head->data_len -= clone->len;
	head->len -= clone->len;
	clone->csum = 0;
	clone->ip_summed = head->ip_summed;
	atomic_add(clone->truesize, &fq->q.net->mem);
	}

	/* We have to remove fragment header from datagram and to relocate
	* header in order to calculate ICV correctly. */
	nhoff = fq->nhoffset;
	skb_network_header(head)[nhoff] = skb_transport_header(head)[0];
	memmove(head->head + sizeof(struct frag_hdr), head->head,
	(head->data - head->head) - sizeof(struct frag_hdr));
	head->mac_header += sizeof(struct frag_hdr);
	head->network_header += sizeof(struct frag_hdr);

	skb_shinfo(head)->frag_list = head->next;
	skb_reset_transport_header(head);
	skb_push(head, head->data - skb_network_header(head));
	atomic_sub(head->truesize, &fq->q.net->mem);

	for (fp=head->next; fp; fp = fp->next) {
	head->data_len += fp->len;
	head->len += fp->len;
	if (head->ip_summed != fp->ip_summed)
	head->ip_summed = CHECKSUM_NONE;
	else if (head->ip_summed == CHECKSUM_COMPLETE)
	head->csum = csum_add(head->csum, fp->csum);
	head->truesize += fp->truesize;
	atomic_sub(fp->truesize, &fq->q.net->mem);
	}

	head->next = NULL;
	head->dev = dev;
	head->tstamp = fq->q.stamp;
	ipv6_hdr(head)->payload_len = htons(payload_len);
	IP6CB(head)->nhoff = nhoff;

	/* Yes, and fold redundant checksum back. 8) */
	if (head->ip_summed == CHECKSUM_COMPLETE)
	head->csum = csum_partial(skb_network_header(head),
	skb_network_header_len(head),
	head->csum);

	rcu_read_lock();
	IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
	rcu_read_unlock();
	fq->q.fragments = NULL;
	return 1;

	out_oversize:
	if (net_ratelimit())
	printk(KERN_DEBUG "ip6_frag_reasm: payload len = %d\n", payload_len);
	goto out_fail;
	out_oom:
	if (net_ratelimit())
	printk(KERN_DEBUG "ip6_frag_reasm: no memory for reassembly\n");
	out_fail:
	rcu_read_lock();
	IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
	rcu_read_unlock();
	return -1;
	}

	static int ipv6_frag_rcv(struct sk_buff *skb)
	{
	struct frag_hdr *fhdr;
	struct frag_queue *fq;
	struct ipv6hdr *hdr = ipv6_hdr(skb);
	struct net *net = dev_net(skb_dst(skb)->dev);

	IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMREQDS);

	/* Jumbo payload inhibits frag. header */
	if (hdr->payload_len==0)
	goto fail_hdr;

	if (!pskb_may_pull(skb, (skb_transport_offset(skb) +
	sizeof(struct frag_hdr))))
	goto fail_hdr;

	hdr = ipv6_hdr(skb);
	fhdr = (struct frag_hdr *)skb_transport_header(skb);

	if (!(fhdr->frag_off & htons(0xFFF9))) {
	/* It is not a fragmented frame */
	skb->transport_header += sizeof(struct frag_hdr);
	IP6_INC_STATS_BH(net,
	ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMOKS);

	IP6CB(skb)->nhoff = (u8 *)fhdr - skb_network_header(skb);
	return 1;
	}

	if (atomic_read(&net->ipv6.frags.mem) > net->ipv6.frags.high_thresh)
	ip6_evictor(net, ip6_dst_idev(skb_dst(skb)));

	if ((fq = fq_find(net, fhdr->identification, &hdr->saddr, &hdr->daddr,
	ip6_dst_idev(skb_dst(skb)))) != NULL) {
	int ret;

	spin_lock(&fq->q.lock);

	ret = ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff);

	spin_unlock(&fq->q.lock);
	fq_put(fq);
	return ret;
	}

	IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMFAILS);
	kfree_skb(skb);
	return -1;

	fail_hdr:
	IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS);
	icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb_network_header_len(skb));
	return -1;
	}

	static const struct inet6_protocol frag_protocol =
	{
	.handler = ipv6_frag_rcv,
	.flags = INET6_PROTO_NOPOLICY,
	};

	#ifdef CONFIG_SYSCTL
	static struct ctl_table ip6_frags_ns_ctl_table[] = {
	{
	.ctl_name = NET_IPV6_IP6FRAG_HIGH_THRESH,
	.procname = "ip6frag_high_thresh",
	.data = &init_net.ipv6.frags.high_thresh,
	.maxlen = sizeof(int),
	.mode = 0644,
	.proc_handler = proc_dointvec
	},
	{
	.ctl_name = NET_IPV6_IP6FRAG_LOW_THRESH,
	.procname = "ip6frag_low_thresh",
	.data = &init_net.ipv6.frags.low_thresh,
	.maxlen = sizeof(int),
	.mode = 0644,
	.proc_handler = proc_dointvec
	},
	{
	.ctl_name = NET_IPV6_IP6FRAG_TIME,
	.procname = "ip6frag_time",
	.data = &init_net.ipv6.frags.timeout,
	.maxlen = sizeof(int),
	.mode = 0644,
	.proc_handler = proc_dointvec_jiffies,
	.strategy = sysctl_jiffies,
	},
	{ }
	};

	static struct ctl_table ip6_frags_ctl_table[] = {
	{
	.ctl_name = NET_IPV6_IP6FRAG_SECRET_INTERVAL,
	.procname = "ip6frag_secret_interval",
	.data = &ip6_frags.secret_interval,
	.maxlen = sizeof(int),
	.mode = 0644,
	.proc_handler = proc_dointvec_jiffies,
	.strategy = sysctl_jiffies
	},
	{ }
	};

	static int ip6_frags_ns_sysctl_register(struct net *net)
	{
	struct ctl_table *table;
	struct ctl_table_header *hdr;

	table = ip6_frags_ns_ctl_table;
	if (net != &init_net) {
	table = kmemdup(table, sizeof(ip6_frags_ns_ctl_table), GFP_KERNEL);
	if (table == NULL)
	goto err_alloc;

	table[0].data = &net->ipv6.frags.high_thresh;
	table[1].data = &net->ipv6.frags.low_thresh;
	table[2].data = &net->ipv6.frags.timeout;
	}

	hdr = register_net_sysctl_table(net, net_ipv6_ctl_path, table);
	if (hdr == NULL)
	goto err_reg;

	net->ipv6.sysctl.frags_hdr = hdr;
	return 0;

	err_reg:
	if (net != &init_net)
	kfree(table);
	err_alloc:
	return -ENOMEM;
	}

	static void ip6_frags_ns_sysctl_unregister(struct net *net)
	{
	struct ctl_table *table;

	table = net->ipv6.sysctl.frags_hdr->ctl_table_arg;
	unregister_net_sysctl_table(net->ipv6.sysctl.frags_hdr);
	kfree(table);
	}

	static struct ctl_table_header *ip6_ctl_header;

	static int ip6_frags_sysctl_register(void)
	{
	ip6_ctl_header = register_net_sysctl_rotable(net_ipv6_ctl_path,
	ip6_frags_ctl_table);
	return ip6_ctl_header == NULL ? -ENOMEM : 0;
	}

	static void ip6_frags_sysctl_unregister(void)
	{
	unregister_net_sysctl_table(ip6_ctl_header);
	}
	#else
	static inline int ip6_frags_ns_sysctl_register(struct net *net)
	{
	return 0;
	}

	static inline void ip6_frags_ns_sysctl_unregister(struct net *net)
	{
	}

	static inline int ip6_frags_sysctl_register(void)
	{
	return 0;
	}

	static inline void ip6_frags_sysctl_unregister(void)
	{
	}
	#endif

	static int ipv6_frags_init_net(struct net *net)
	{
	net->ipv6.frags.high_thresh = 256 * 1024;
	net->ipv6.frags.low_thresh = 192 * 1024;
	net->ipv6.frags.timeout = IPV6_FRAG_TIMEOUT;

	inet_frags_init_net(&net->ipv6.frags);

	return ip6_frags_ns_sysctl_register(net);
	}

	static void ipv6_frags_exit_net(struct net *net)
	{
	ip6_frags_ns_sysctl_unregister(net);
	inet_frags_exit_net(&net->ipv6.frags, &ip6_frags);
	}

	static struct pernet_operations ip6_frags_ops = {
	.init = ipv6_frags_init_net,
	.exit = ipv6_frags_exit_net,
	};

	int __init ipv6_frag_init(void)
	{
	int ret;

	ret = inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT);
	if (ret)
	goto out;

	ret = ip6_frags_sysctl_register();
	if (ret)
	goto err_sysctl;

	ret = register_pernet_subsys(&ip6_frags_ops);
	if (ret)
	goto err_pernet;

	ip6_frags.hashfn = ip6_hashfn;
	ip6_frags.constructor = ip6_frag_init;
	ip6_frags.destructor = NULL;
	ip6_frags.skb_free = NULL;
	ip6_frags.qsize = sizeof(struct frag_queue);
	ip6_frags.match = ip6_frag_match;
	ip6_frags.frag_expire = ip6_frag_expire;
	ip6_frags.secret_interval = 10 * 60 * HZ;
	inet_frags_init(&ip6_frags);
	out:
	return ret;

	err_pernet:
	ip6_frags_sysctl_unregister();
	err_sysctl:
	inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
	goto out;
	}

	void ipv6_frag_exit(void)
	{
	inet_frags_fini(&ip6_frags);
	ip6_frags_sysctl_unregister();
	unregister_pernet_subsys(&ip6_frags_ops);
	inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
	}