[deliverable/linux.git] / net / ieee802154 / reassembly.c

/*	6LoWPAN fragment reassembly
 *
 *
 *	Authors:
 *	Alexander Aring		<aar@pengutronix.de>
 *
 *	Based on: net/ipv6/reassembly.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.
 */

#define pr_fmt(fmt) "6LoWPAN: " fmt

#include <linux/net.h>
#include <linux/list.h>
#include <linux/netdevice.h>
#include <linux/random.h>
#include <linux/jhash.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/export.h>

#include <net/ieee802154_netdev.h>
#include <net/6lowpan.h>
#include <net/ipv6.h>
#include <net/inet_frag.h>

#include "reassembly.h"

static struct inet_frags lowpan_frags;

static int lowpan_frag_reasm(struct lowpan_frag_queue *fq,
			     struct sk_buff *prev, struct net_device *dev);

static unsigned int lowpan_hash_frag(__be16 tag, u16 d_size,
				     const struct ieee802154_addr *saddr,
				     const struct ieee802154_addr *daddr)
{
	u32 c;

	net_get_random_once(&lowpan_frags.rnd, sizeof(lowpan_frags.rnd));
	c = jhash_3words(ieee802154_addr_hash(saddr),
			 ieee802154_addr_hash(daddr),
			 (__force u32)(tag + (d_size << 16)),
			 lowpan_frags.rnd);

	return c & (INETFRAGS_HASHSZ - 1);
}

static unsigned int lowpan_hashfn(struct inet_frag_queue *q)
{
	struct lowpan_frag_queue *fq;

	fq = container_of(q, struct lowpan_frag_queue, q);
	return lowpan_hash_frag(fq->tag, fq->d_size, &fq->saddr, &fq->daddr);
}

static bool lowpan_frag_match(struct inet_frag_queue *q, void *a)
{
	struct lowpan_frag_queue *fq;
	struct lowpan_create_arg *arg = a;

	fq = container_of(q, struct lowpan_frag_queue, q);
	return	fq->tag == arg->tag && fq->d_size == arg->d_size &&
		ieee802154_addr_equal(&fq->saddr, arg->src) &&
		ieee802154_addr_equal(&fq->daddr, arg->dst);
}

static void lowpan_frag_init(struct inet_frag_queue *q, void *a)
{
	struct lowpan_frag_queue *fq;
	struct lowpan_create_arg *arg = a;

	fq = container_of(q, struct lowpan_frag_queue, q);

	fq->tag = arg->tag;
	fq->d_size = arg->d_size;
	fq->saddr = *arg->src;
	fq->daddr = *arg->dst;
}

static void lowpan_frag_expire(unsigned long data)
{
	struct frag_queue *fq;
	struct net *net;

	fq = container_of((struct inet_frag_queue *)data, struct frag_queue, q);
	net = container_of(fq->q.net, struct net, ieee802154_lowpan.frags);

	spin_lock(&fq->q.lock);

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

	inet_frag_kill(&fq->q, &lowpan_frags);
out:
	spin_unlock(&fq->q.lock);
	inet_frag_put(&fq->q, &lowpan_frags);
}

static inline struct lowpan_frag_queue *
fq_find(struct net *net, const struct ieee802154_frag_info *frag_info,
	const struct ieee802154_addr *src,
	const struct ieee802154_addr *dst)
{
	struct inet_frag_queue *q;
	struct lowpan_create_arg arg;
	unsigned int hash;

	arg.tag = frag_info->d_tag;
	arg.d_size = frag_info->d_size;
	arg.src = src;
	arg.dst = dst;

	read_lock(&lowpan_frags.lock);
	hash = lowpan_hash_frag(frag_info->d_tag, frag_info->d_size, src, dst);

	q = inet_frag_find(&net->ieee802154_lowpan.frags,
			   &lowpan_frags, &arg, hash);
	if (IS_ERR_OR_NULL(q)) {
		inet_frag_maybe_warn_overflow(q, pr_fmt());
		return NULL;
	}
	return container_of(q, struct lowpan_frag_queue, q);
}

static int lowpan_frag_queue(struct lowpan_frag_queue *fq,
			     struct sk_buff *skb, const u8 frag_type)
{
	struct sk_buff *prev, *next;
	struct net_device *dev;
	int end, offset;

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

	offset = mac_cb(skb)->frag_info.d_offset << 3;
	end = mac_cb(skb)->frag_info.d_size;

	/* Is this the final fragment? */
	if (offset + skb->len == end) {
		/* 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 {
		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;
		}
	}

	/* 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 = fq->q.fragments_tail;
	if (!prev || mac_cb(prev)->frag_info.d_offset <
		     mac_cb(skb)->frag_info.d_offset) {
		next = NULL;
		goto found;
	}
	prev = NULL;
	for (next = fq->q.fragments; next != NULL; next = next->next) {
		if (mac_cb(next)->frag_info.d_offset >=
		    mac_cb(skb)->frag_info.d_offset)
			break;	/* bingo! */
		prev = next;
	}

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

	dev = skb->dev;
	if (dev)
		skb->dev = NULL;

	fq->q.stamp = skb->tstamp;
	if (frag_type == LOWPAN_DISPATCH_FRAG1) {
		/* Calculate uncomp. 6lowpan header to estimate full size */
		fq->q.meat += lowpan_uncompress_size(skb, NULL);
		fq->q.last_in |= INET_FRAG_FIRST_IN;
	} else {
		fq->q.meat += skb->len;
	}
	add_frag_mem_limit(&fq->q, skb->truesize);

	if (fq->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
	    fq->q.meat == fq->q.len) {
		int res;
		unsigned long orefdst = skb->_skb_refdst;

		skb->_skb_refdst = 0UL;
		res = lowpan_frag_reasm(fq, prev, dev);
		skb->_skb_refdst = orefdst;
		return res;
	}

	inet_frag_lru_move(&fq->q);
	return -1;
err:
	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 lowpan_frag_reasm(struct lowpan_frag_queue *fq, struct sk_buff *prev,
			     struct net_device *dev)
{
	struct sk_buff *fp, *head = fq->q.fragments;
	int sum_truesize;

	inet_frag_kill(&fq->q, &lowpan_frags);

	/* 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;
		if (!fp->next)
			fq->q.fragments_tail = fp;
		prev->next = fp;

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

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

	/* Head of list must not be cloned. */
	if (skb_unclone(head, 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_frag_list(head)) {
		struct sk_buff *clone;
		int i, plen = 0;

		clone = alloc_skb(0, GFP_ATOMIC);
		if (!clone)
			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_frag_size(&skb_shinfo(head)->frags[i]);
		clone->len = head->data_len - plen;
		clone->data_len = clone->len;
		head->data_len -= clone->len;
		head->len -= clone->len;
		add_frag_mem_limit(&fq->q, clone->truesize);
	}

	WARN_ON(head == NULL);

	sum_truesize = head->truesize;
	for (fp = head->next; fp;) {
		bool headstolen;
		int delta;
		struct sk_buff *next = fp->next;

		sum_truesize += fp->truesize;
		if (skb_try_coalesce(head, fp, &headstolen, &delta)) {
			kfree_skb_partial(fp, headstolen);
		} else {
			if (!skb_shinfo(head)->frag_list)
				skb_shinfo(head)->frag_list = fp;
			head->data_len += fp->len;
			head->len += fp->len;
			head->truesize += fp->truesize;
		}
		fp = next;
	}
	sub_frag_mem_limit(&fq->q, sum_truesize);

	head->next = NULL;
	head->dev = dev;
	head->tstamp = fq->q.stamp;

	fq->q.fragments = NULL;
	fq->q.fragments_tail = NULL;

	return 1;
out_oom:
	net_dbg_ratelimited("lowpan_frag_reasm: no memory for reassembly\n");
	return -1;
}

static int lowpan_get_frag_info(struct sk_buff *skb, const u8 frag_type,
				struct ieee802154_frag_info *frag_info)
{
	bool fail;
	u8 pattern = 0, low = 0;

	fail = lowpan_fetch_skb(skb, &pattern, 1);
	fail |= lowpan_fetch_skb(skb, &low, 1);
	frag_info->d_size = (pattern & 7) << 8 | low;
	fail |= lowpan_fetch_skb(skb, &frag_info->d_tag, 2);

	if (frag_type == LOWPAN_DISPATCH_FRAGN) {
		fail |= lowpan_fetch_skb(skb, &frag_info->d_offset, 1);
	} else {
		skb_reset_network_header(skb);
		frag_info->d_offset = 0;
	}

	if (unlikely(fail))
		return -EIO;

	return 0;
}

int lowpan_frag_rcv(struct sk_buff *skb, const u8 frag_type)
{
	struct lowpan_frag_queue *fq;
	struct net *net = dev_net(skb->dev);
	struct ieee802154_frag_info *frag_info = &mac_cb(skb)->frag_info;
	struct ieee802154_addr source, dest;
	int err;

	source = mac_cb(skb)->source;
	dest = mac_cb(skb)->dest;

	err = lowpan_get_frag_info(skb, frag_type, frag_info);
	if (err < 0)
		goto err;

	if (frag_info->d_size > net->ieee802154_lowpan.max_dsize)
		goto err;

	inet_frag_evictor(&net->ieee802154_lowpan.frags, &lowpan_frags, false);

	fq = fq_find(net, frag_info, &source, &dest);
	if (fq != NULL) {
		int ret;
		spin_lock(&fq->q.lock);
		ret = lowpan_frag_queue(fq, skb, frag_type);
		spin_unlock(&fq->q.lock);

		inet_frag_put(&fq->q, &lowpan_frags);
		return ret;
	}

err:
	kfree_skb(skb);
	return -1;
}
EXPORT_SYMBOL(lowpan_frag_rcv);

#ifdef CONFIG_SYSCTL
static struct ctl_table lowpan_frags_ns_ctl_table[] = {
	{
		.procname	= "6lowpanfrag_high_thresh",
		.data		= &init_net.ieee802154_lowpan.frags.high_thresh,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec
	},
	{
		.procname	= "6lowpanfrag_low_thresh",
		.data		= &init_net.ieee802154_lowpan.frags.low_thresh,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec
	},
	{
		.procname	= "6lowpanfrag_time",
		.data		= &init_net.ieee802154_lowpan.frags.timeout,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_jiffies,
	},
	{
		.procname	= "6lowpanfrag_max_datagram_size",
		.data		= &init_net.ieee802154_lowpan.max_dsize,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec
	},
	{ }
};

static struct ctl_table lowpan_frags_ctl_table[] = {
	{
		.procname	= "6lowpanfrag_secret_interval",
		.data		= &lowpan_frags.secret_interval,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_jiffies,
	},
	{ }
};

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

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

		table[0].data = &net->ieee802154_lowpan.frags.high_thresh;
		table[1].data = &net->ieee802154_lowpan.frags.low_thresh;
		table[2].data = &net->ieee802154_lowpan.frags.timeout;
		table[3].data = &net->ieee802154_lowpan.max_dsize;

		/* Don't export sysctls to unprivileged users */
		if (net->user_ns != &init_user_ns)
			table[0].procname = NULL;
	}

	hdr = register_net_sysctl(net, "net/ieee802154/6lowpan", table);
	if (hdr == NULL)
		goto err_reg;

	net->ieee802154_lowpan.sysctl.frags_hdr = hdr;
	return 0;

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

static void __net_exit lowpan_frags_ns_sysctl_unregister(struct net *net)
{
	struct ctl_table *table;

	table = net->ieee802154_lowpan.sysctl.frags_hdr->ctl_table_arg;
	unregister_net_sysctl_table(net->ieee802154_lowpan.sysctl.frags_hdr);
	if (!net_eq(net, &init_net))
		kfree(table);
}

static struct ctl_table_header *lowpan_ctl_header;

static int lowpan_frags_sysctl_register(void)
{
	lowpan_ctl_header = register_net_sysctl(&init_net,
						"net/ieee802154/6lowpan",
						lowpan_frags_ctl_table);
	return lowpan_ctl_header == NULL ? -ENOMEM : 0;
}

static void lowpan_frags_sysctl_unregister(void)
{
	unregister_net_sysctl_table(lowpan_ctl_header);
}
#else
static inline int lowpan_frags_ns_sysctl_register(struct net *net)
{
	return 0;
}

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

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

static inline void lowpan_frags_sysctl_unregister(void)
{
}
#endif

static int __net_init lowpan_frags_init_net(struct net *net)
{
	net->ieee802154_lowpan.frags.high_thresh = IPV6_FRAG_HIGH_THRESH;
	net->ieee802154_lowpan.frags.low_thresh = IPV6_FRAG_LOW_THRESH;
	net->ieee802154_lowpan.frags.timeout = IPV6_FRAG_TIMEOUT;
	net->ieee802154_lowpan.max_dsize = 0xFFFF;

	inet_frags_init_net(&net->ieee802154_lowpan.frags);

	return lowpan_frags_ns_sysctl_register(net);
}

static void __net_exit lowpan_frags_exit_net(struct net *net)
{
	lowpan_frags_ns_sysctl_unregister(net);
	inet_frags_exit_net(&net->ieee802154_lowpan.frags, &lowpan_frags);
}

static struct pernet_operations lowpan_frags_ops = {
	.init = lowpan_frags_init_net,
	.exit = lowpan_frags_exit_net,
};

int __init lowpan_net_frag_init(void)
{
	int ret;

	ret = lowpan_frags_sysctl_register();
	if (ret)
		return ret;

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

	lowpan_frags.hashfn = lowpan_hashfn;
	lowpan_frags.constructor = lowpan_frag_init;
	lowpan_frags.destructor = NULL;
	lowpan_frags.skb_free = NULL;
	lowpan_frags.qsize = sizeof(struct frag_queue);
	lowpan_frags.match = lowpan_frag_match;
	lowpan_frags.frag_expire = lowpan_frag_expire;
	lowpan_frags.secret_interval = 10 * 60 * HZ;
	inet_frags_init(&lowpan_frags);

	return ret;
err_pernet:
	lowpan_frags_sysctl_unregister();
	return ret;
}

void lowpan_net_frag_exit(void)
{
	inet_frags_fini(&lowpan_frags);
	lowpan_frags_sysctl_unregister();
	unregister_pernet_subsys(&lowpan_frags_ops);
}
Commit	Line	Data
7240cdec AA	1	/* 6LoWPAN fragment reassembly
	2	*
	3	*
	4	* Authors:
	5	* Alexander Aring <aar@pengutronix.de>
	6	*
	7	* Based on: net/ipv6/reassembly.c
	8	*
	9	* This program is free software; you can redistribute it and/or
	10	* modify it under the terms of the GNU General Public License
	11	* as published by the Free Software Foundation; either version
	12	* 2 of the License, or (at your option) any later version.
	13	*/
	14
	15	#define pr_fmt(fmt) "6LoWPAN: " fmt
	16
	17	#include <linux/net.h>
	18	#include <linux/list.h>
	19	#include <linux/netdevice.h>
	20	#include <linux/random.h>
	21	#include <linux/jhash.h>
	22	#include <linux/skbuff.h>
	23	#include <linux/slab.h>
	24	#include <linux/export.h>
	25
	26	#include <net/ieee802154_netdev.h>
cefc8c8a	27	#include <net/6lowpan.h>
7240cdec AA	28	#include <net/ipv6.h>
	29	#include <net/inet_frag.h>
	30
7240cdec AA	31	#include "reassembly.h"
	32
	33	static struct inet_frags lowpan_frags;
	34
	35	static int lowpan_frag_reasm(struct lowpan_frag_queue *fq,
	36	struct sk_buff prev, struct net_device dev);
	37
4c7f778e	38	static unsigned int lowpan_hash_frag(__be16 tag, u16 d_size,
ae531b94 PB	39	const struct ieee802154_addr *saddr,
ae531b94 PB	40	const struct ieee802154_addr *daddr)
7240cdec AA	41	{
	42	u32 c;
	43
	44	net_get_random_once(&lowpan_frags.rnd, sizeof(lowpan_frags.rnd));
	45	c = jhash_3words(ieee802154_addr_hash(saddr),
	46	ieee802154_addr_hash(daddr),
	47	(__force u32)(tag + (d_size << 16)),
	48	lowpan_frags.rnd);
	49
	50	return c & (INETFRAGS_HASHSZ - 1);
	51	}
	52
	53	static unsigned int lowpan_hashfn(struct inet_frag_queue *q)
	54	{
	55	struct lowpan_frag_queue *fq;
	56
	57	fq = container_of(q, struct lowpan_frag_queue, q);
	58	return lowpan_hash_frag(fq->tag, fq->d_size, &fq->saddr, &fq->daddr);
	59	}
	60
17794326	61	static bool lowpan_frag_match(struct inet_frag_queue q, void a)
7240cdec AA	62	{
	63	struct lowpan_frag_queue *fq;
	64	struct lowpan_create_arg *arg = a;
	65
	66	fq = container_of(q, struct lowpan_frag_queue, q);
	67	return fq->tag == arg->tag && fq->d_size == arg->d_size &&
ae531b94 PB	68	ieee802154_addr_equal(&fq->saddr, arg->src) &&
ae531b94 PB	69	ieee802154_addr_equal(&fq->daddr, arg->dst);
7240cdec	70	}
7240cdec	71
17794326	72	static void lowpan_frag_init(struct inet_frag_queue q, void a)
7240cdec AA	73	{
	74	struct lowpan_frag_queue *fq;
	75	struct lowpan_create_arg *arg = a;
	76
	77	fq = container_of(q, struct lowpan_frag_queue, q);
	78
	79	fq->tag = arg->tag;
	80	fq->d_size = arg->d_size;
	81	fq->saddr = *arg->src;
	82	fq->daddr = *arg->dst;
	83	}
7240cdec AA	84
	85	static void lowpan_frag_expire(unsigned long data)
	86	{
	87	struct frag_queue *fq;
	88	struct net *net;
	89
	90	fq = container_of((struct inet_frag_queue *)data, struct frag_queue, q);
	91	net = container_of(fq->q.net, struct net, ieee802154_lowpan.frags);
	92
17794326 FW	93	spin_lock(&fq->q.lock);
	94
	95	if (fq->q.last_in & INET_FRAG_COMPLETE)
	96	goto out;
	97
	98	inet_frag_kill(&fq->q, &lowpan_frags);
	99	out:
	100	spin_unlock(&fq->q.lock);
	101	inet_frag_put(&fq->q, &lowpan_frags);
7240cdec AA	102	}
	103
	104	static inline struct lowpan_frag_queue *
	105	fq_find(struct net net, const struct ieee802154_frag_info frag_info,
ae531b94 PB	106	const struct ieee802154_addr *src,
ae531b94 PB	107	const struct ieee802154_addr *dst)
7240cdec AA	108	{
	109	struct inet_frag_queue *q;
	110	struct lowpan_create_arg arg;
	111	unsigned int hash;
	112
	113	arg.tag = frag_info->d_tag;
	114	arg.d_size = frag_info->d_size;
	115	arg.src = src;
	116	arg.dst = dst;
	117
	118	read_lock(&lowpan_frags.lock);
	119	hash = lowpan_hash_frag(frag_info->d_tag, frag_info->d_size, src, dst);
	120
	121	q = inet_frag_find(&net->ieee802154_lowpan.frags,
	122	&lowpan_frags, &arg, hash);
	123	if (IS_ERR_OR_NULL(q)) {
	124	inet_frag_maybe_warn_overflow(q, pr_fmt());
	125	return NULL;
	126	}
	127	return container_of(q, struct lowpan_frag_queue, q);
	128	}
	129
	130	static int lowpan_frag_queue(struct lowpan_frag_queue *fq,
	131	struct sk_buff *skb, const u8 frag_type)
	132	{
	133	struct sk_buff prev, next;
	134	struct net_device *dev;
	135	int end, offset;
	136
	137	if (fq->q.last_in & INET_FRAG_COMPLETE)
	138	goto err;
	139
	140	offset = mac_cb(skb)->frag_info.d_offset << 3;
	141	end = mac_cb(skb)->frag_info.d_size;
	142
	143	/* Is this the final fragment? */
	144	if (offset + skb->len == end) {
	145	/* If we already have some bits beyond end
	146	* or have different end, the segment is corrupted.
	147	*/
	148	if (end < fq->q.len \|\|
	149	((fq->q.last_in & INET_FRAG_LAST_IN) && end != fq->q.len))
	150	goto err;
	151	fq->q.last_in \|= INET_FRAG_LAST_IN;
	152	fq->q.len = end;
	153	} else {
	154	if (end > fq->q.len) {
	155	/* Some bits beyond end -> corruption. */
	156	if (fq->q.last_in & INET_FRAG_LAST_IN)
	157	goto err;
	158	fq->q.len = end;
	159	}
	160	}
	161
	162	/* Find out which fragments are in front and at the back of us
	163	* in the chain of fragments so far. We must know where to put
	164	* this fragment, right?
	165	*/
	166	prev = fq->q.fragments_tail;
	167	if (!prev \|\| mac_cb(prev)->frag_info.d_offset <
	168	mac_cb(skb)->frag_info.d_offset) {
	169	next = NULL;
	170	goto found;
	171	}
172	prev = NULL;
173	for (next = fq->q.fragments; next != NULL; next = next->next) {
174	if (mac_cb(next)->frag_info.d_offset >=
175	mac_cb(skb)->frag_info.d_offset)
176	break; /* bingo! */
177	prev = next;
178	}
179
180	found:
181	/* Insert this fragment in the chain of fragments. */
182	skb->next = next;
183	if (!next)
184	fq->q.fragments_tail = skb;
185	if (prev)
186	prev->next = skb;
187	else
188	fq->q.fragments = skb;
189
190	dev = skb->dev;
191	if (dev)
192	skb->dev = NULL;
193
194	fq->q.stamp = skb->tstamp;
195	if (frag_type == LOWPAN_DISPATCH_FRAG1) {
196	/* Calculate uncomp. 6lowpan header to estimate full size */
197	fq->q.meat += lowpan_uncompress_size(skb, NULL);
198	fq->q.last_in \|= INET_FRAG_FIRST_IN;
199	} else {
200	fq->q.meat += skb->len;
201	}
202	add_frag_mem_limit(&fq->q, skb->truesize);
203
204	if (fq->q.last_in == (INET_FRAG_FIRST_IN \| INET_FRAG_LAST_IN) &&
205	fq->q.meat == fq->q.len) {
206	int res;
207	unsigned long orefdst = skb->_skb_refdst;
208
209	skb->_skb_refdst = 0UL;
210	res = lowpan_frag_reasm(fq, prev, dev);
211	skb->_skb_refdst = orefdst;
212	return res;
213	}
214
215	inet_frag_lru_move(&fq->q);
216	return -1;
217	err:
218	kfree_skb(skb);
219	return -1;
220	}
221
222	/* Check if this packet is complete.
223	* Returns NULL on failure by any reason, and pointer
224	* to current nexthdr field in reassembled frame.
225	*
226	* It is called with locked fq, and caller must check that
227	* queue is eligible for reassembly i.e. it is not COMPLETE,
228	* the last and the first frames arrived and all the bits are here.
229	*/
230	static int lowpan_frag_reasm(struct lowpan_frag_queue fq, struct sk_buff prev,
231	struct net_device *dev)
232	{
233	struct sk_buff fp, head = fq->q.fragments;
234	int sum_truesize;
235
236	inet_frag_kill(&fq->q, &lowpan_frags);
237
238	/* Make the one we just received the head. */
239	if (prev) {
240	head = prev->next;
241	fp = skb_clone(head, GFP_ATOMIC);
242
243	if (!fp)
244	goto out_oom;
245
246	fp->next = head->next;
247	if (!fp->next)
248	fq->q.fragments_tail = fp;
249	prev->next = fp;
250
251	skb_morph(head, fq->q.fragments);
252	head->next = fq->q.fragments->next;
253
254	consume_skb(fq->q.fragments);
255	fq->q.fragments = head;
256	}
257
258	/* Head of list must not be cloned. */
259	if (skb_unclone(head, GFP_ATOMIC))
260	goto out_oom;
261
262	/* If the first fragment is fragmented itself, we split
263	* it to two chunks: the first with data and paged part
264	* and the second, holding only fragments.
265	*/
266	if (skb_has_frag_list(head)) {
267	struct sk_buff *clone;
268	int i, plen = 0;
269
270	clone = alloc_skb(0, GFP_ATOMIC);
271	if (!clone)
272	goto out_oom;
273	clone->next = head->next;
274	head->next = clone;
275	skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
276	skb_frag_list_init(head);
277	for (i = 0; i < skb_shinfo(head)->nr_frags; i++)
278	plen += skb_frag_size(&skb_shinfo(head)->frags[i]);
279	clone->len = head->data_len - plen;
280	clone->data_len = clone->len;
281	head->data_len -= clone->len;
282	head->len -= clone->len;
283	add_frag_mem_limit(&fq->q, clone->truesize);
284	}
285
286	WARN_ON(head == NULL);
287
288	sum_truesize = head->truesize;
289	for (fp = head->next; fp;) {
290	bool headstolen;
291	int delta;
292	struct sk_buff *next = fp->next;
293
294	sum_truesize += fp->truesize;
295	if (skb_try_coalesce(head, fp, &headstolen, &delta)) {
296	kfree_skb_partial(fp, headstolen);
297	} else {
298	if (!skb_shinfo(head)->frag_list)
299	skb_shinfo(head)->frag_list = fp;
300	head->data_len += fp->len;
301	head->len += fp->len;
302	head->truesize += fp->truesize;
303	}
304	fp = next;
305	}
306	sub_frag_mem_limit(&fq->q, sum_truesize);
307
308	head->next = NULL;
309	head->dev = dev;
310	head->tstamp = fq->q.stamp;
311
312	fq->q.fragments = NULL;
313	fq->q.fragments_tail = NULL;
314
315	return 1;
316	out_oom:
317	net_dbg_ratelimited("lowpan_frag_reasm: no memory for reassembly\n");
318	return -1;
319	}
320
321	static int lowpan_get_frag_info(struct sk_buff *skb, const u8 frag_type,
322	struct ieee802154_frag_info *frag_info)
323	{
324	bool fail;
325	u8 pattern = 0, low = 0;
326
327	fail = lowpan_fetch_skb(skb, &pattern, 1);
328	fail \|= lowpan_fetch_skb(skb, &low, 1);
329	frag_info->d_size = (pattern & 7) << 8 \| low;
330	fail \|= lowpan_fetch_skb(skb, &frag_info->d_tag, 2);
331
332	if (frag_type == LOWPAN_DISPATCH_FRAGN) {
333	fail \|= lowpan_fetch_skb(skb, &frag_info->d_offset, 1);
334	} else {
335	skb_reset_network_header(skb);
336	frag_info->d_offset = 0;
337	}
338
339	if (unlikely(fail))
340	return -EIO;
341
342	return 0;
343	}
344
345	int lowpan_frag_rcv(struct sk_buff *skb, const u8 frag_type)
346	{
347	struct lowpan_frag_queue *fq;
348	struct net *net = dev_net(skb->dev);
349	struct ieee802154_frag_info *frag_info = &mac_cb(skb)->frag_info;
ae531b94	350	struct ieee802154_addr source, dest;
7240cdec AA	351	int err;
7240cdec AA	352
ae531b94 PB	353	source = mac_cb(skb)->source;
	354	dest = mac_cb(skb)->dest;
	355
7240cdec AA	356	err = lowpan_get_frag_info(skb, frag_type, frag_info);
	357	if (err < 0)
	358	goto err;
	359
	360	if (frag_info->d_size > net->ieee802154_lowpan.max_dsize)
	361	goto err;
	362
	363	inet_frag_evictor(&net->ieee802154_lowpan.frags, &lowpan_frags, false);
	364
ae531b94	365	fq = fq_find(net, frag_info, &source, &dest);
7240cdec AA	366	if (fq != NULL) {
	367	int ret;
	368	spin_lock(&fq->q.lock);
	369	ret = lowpan_frag_queue(fq, skb, frag_type);
	370	spin_unlock(&fq->q.lock);
	371
	372	inet_frag_put(&fq->q, &lowpan_frags);
	373	return ret;
	374	}
	375
	376	err:
	377	kfree_skb(skb);
	378	return -1;
	379	}
	380	EXPORT_SYMBOL(lowpan_frag_rcv);
	381
	382	#ifdef CONFIG_SYSCTL
	383	static struct ctl_table lowpan_frags_ns_ctl_table[] = {
	384	{
	385	.procname = "6lowpanfrag_high_thresh",
	386	.data = &init_net.ieee802154_lowpan.frags.high_thresh,
	387	.maxlen = sizeof(int),
	388	.mode = 0644,
	389	.proc_handler = proc_dointvec
	390	},
	391	{
	392	.procname = "6lowpanfrag_low_thresh",
	393	.data = &init_net.ieee802154_lowpan.frags.low_thresh,
	394	.maxlen = sizeof(int),
	395	.mode = 0644,
	396	.proc_handler = proc_dointvec
	397	},
	398	{
	399	.procname = "6lowpanfrag_time",
	400	.data = &init_net.ieee802154_lowpan.frags.timeout,
	401	.maxlen = sizeof(int),
	402	.mode = 0644,
	403	.proc_handler = proc_dointvec_jiffies,
	404	},
	405	{
	406	.procname = "6lowpanfrag_max_datagram_size",
	407	.data = &init_net.ieee802154_lowpan.max_dsize,
	408	.maxlen = sizeof(int),
	409	.mode = 0644,
	410	.proc_handler = proc_dointvec
	411	},
	412	{ }
	413	};
	414
	415	static struct ctl_table lowpan_frags_ctl_table[] = {
	416	{
	417	.procname = "6lowpanfrag_secret_interval",
	418	.data = &lowpan_frags.secret_interval,
	419	.maxlen = sizeof(int),
	420	.mode = 0644,
	421	.proc_handler = proc_dointvec_jiffies,
	422	},
	423	{ }
	424	};
	425
	426	static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
	427	{
	428	struct ctl_table *table;
	429	struct ctl_table_header *hdr;
430
431	table = lowpan_frags_ns_ctl_table;
432	if (!net_eq(net, &init_net)) {
433	table = kmemdup(table, sizeof(lowpan_frags_ns_ctl_table),
434	GFP_KERNEL);
435	if (table == NULL)
436	goto err_alloc;
437
438	table[0].data = &net->ieee802154_lowpan.frags.high_thresh;
439	table[1].data = &net->ieee802154_lowpan.frags.low_thresh;
440	table[2].data = &net->ieee802154_lowpan.frags.timeout;
3772ab1d	441	table[3].data = &net->ieee802154_lowpan.max_dsize;
7240cdec AA	442
	443	/* Don't export sysctls to unprivileged users */
	444	if (net->user_ns != &init_user_ns)
	445	table[0].procname = NULL;
	446	}
	447
	448	hdr = register_net_sysctl(net, "net/ieee802154/6lowpan", table);
	449	if (hdr == NULL)
	450	goto err_reg;
	451
	452	net->ieee802154_lowpan.sysctl.frags_hdr = hdr;
	453	return 0;
	454
	455	err_reg:
	456	if (!net_eq(net, &init_net))
	457	kfree(table);
	458	err_alloc:
	459	return -ENOMEM;
	460	}
	461
	462	static void __net_exit lowpan_frags_ns_sysctl_unregister(struct net *net)
	463	{
	464	struct ctl_table *table;
	465
	466	table = net->ieee802154_lowpan.sysctl.frags_hdr->ctl_table_arg;
	467	unregister_net_sysctl_table(net->ieee802154_lowpan.sysctl.frags_hdr);
	468	if (!net_eq(net, &init_net))
	469	kfree(table);
	470	}
	471
	472	static struct ctl_table_header *lowpan_ctl_header;
	473
	474	static int lowpan_frags_sysctl_register(void)
	475	{
	476	lowpan_ctl_header = register_net_sysctl(&init_net,
	477	"net/ieee802154/6lowpan",
	478	lowpan_frags_ctl_table);
	479	return lowpan_ctl_header == NULL ? -ENOMEM : 0;
	480	}
	481
	482	static void lowpan_frags_sysctl_unregister(void)
	483	{
	484	unregister_net_sysctl_table(lowpan_ctl_header);
	485	}
	486	#else
	487	static inline int lowpan_frags_ns_sysctl_register(struct net *net)
	488	{
	489	return 0;
	490	}
	491
	492	static inline void lowpan_frags_ns_sysctl_unregister(struct net *net)
	493	{
	494	}
	495
	496	static inline int lowpan_frags_sysctl_register(void)
	497	{
	498	return 0;
	499	}
	500
	501	static inline void lowpan_frags_sysctl_unregister(void)
	502	{
	503	}
	504	#endif
	505
506	static int __net_init lowpan_frags_init_net(struct net *net)
507	{
508	net->ieee802154_lowpan.frags.high_thresh = IPV6_FRAG_HIGH_THRESH;
509	net->ieee802154_lowpan.frags.low_thresh = IPV6_FRAG_LOW_THRESH;
510	net->ieee802154_lowpan.frags.timeout = IPV6_FRAG_TIMEOUT;
511	net->ieee802154_lowpan.max_dsize = 0xFFFF;
512
513	inet_frags_init_net(&net->ieee802154_lowpan.frags);
514
515	return lowpan_frags_ns_sysctl_register(net);
516	}
517
518	static void __net_exit lowpan_frags_exit_net(struct net *net)
519	{
520	lowpan_frags_ns_sysctl_unregister(net);
521	inet_frags_exit_net(&net->ieee802154_lowpan.frags, &lowpan_frags);
522	}
523
524	static struct pernet_operations lowpan_frags_ops = {
525	.init = lowpan_frags_init_net,
526	.exit = lowpan_frags_exit_net,
527	};
528
529	int __init lowpan_net_frag_init(void)
530	{
531	int ret;
532
533	ret = lowpan_frags_sysctl_register();
534	if (ret)
37147652	535	return ret;
7240cdec AA	536
	537	ret = register_pernet_subsys(&lowpan_frags_ops);
	538	if (ret)
	539	goto err_pernet;
	540
	541	lowpan_frags.hashfn = lowpan_hashfn;
	542	lowpan_frags.constructor = lowpan_frag_init;
	543	lowpan_frags.destructor = NULL;
	544	lowpan_frags.skb_free = NULL;
	545	lowpan_frags.qsize = sizeof(struct frag_queue);
	546	lowpan_frags.match = lowpan_frag_match;
	547	lowpan_frags.frag_expire = lowpan_frag_expire;
	548	lowpan_frags.secret_interval = 10 * 60 * HZ;
	549	inet_frags_init(&lowpan_frags);
37147652 AA	550
37147652 AA	551	return ret;
7240cdec AA	552	err_pernet:
7240cdec AA	553	lowpan_frags_sysctl_unregister();
7240cdec AA	554	return ret;
	555	}
	556
	557	void lowpan_net_frag_exit(void)
	558	{
	559	inet_frags_fini(&lowpan_frags);
	560	lowpan_frags_sysctl_unregister();
	561	unregister_pernet_subsys(&lowpan_frags_ops);
	562	}