[linux-2.6-block.git] / net / ieee802154 / 6lowpan / reassembly.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*	6LoWPAN fragment reassembly
 *
 *	Authors:
 *	Alexander Aring		<aar@pengutronix.de>
 *
 *	Based on: net/ipv6/reassembly.c
 */

#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_frag.h>
#include <net/inet_frag.h>
#include <net/ip.h>

#include "6lowpan_i.h"

static const char lowpan_frags_cache_name[] = "lowpan-frags";

static struct inet_frags lowpan_frags;

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

static void lowpan_frag_init(struct inet_frag_queue *q, const void *a)
{
	const struct frag_lowpan_compare_key *key = a;

	BUILD_BUG_ON(sizeof(*key) > sizeof(q->key));
	memcpy(&q->key, key, sizeof(*key));
}

static void lowpan_frag_expire(struct timer_list *t)
{
	struct inet_frag_queue *frag = from_timer(frag, t, timer);
	struct frag_queue *fq;

	fq = container_of(frag, struct frag_queue, q);

	spin_lock(&fq->q.lock);

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

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

static inline struct lowpan_frag_queue *
fq_find(struct net *net, const struct lowpan_802154_cb *cb,
	const struct ieee802154_addr *src,
	const struct ieee802154_addr *dst)
{
	struct netns_ieee802154_lowpan *ieee802154_lowpan =
		net_ieee802154_lowpan(net);
	struct frag_lowpan_compare_key key = {};
	struct inet_frag_queue *q;

	key.tag = cb->d_tag;
	key.d_size = cb->d_size;
	key.src = *src;
	key.dst = *dst;

	q = inet_frag_find(&ieee802154_lowpan->frags, &key);
	if (!q)
		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, u8 frag_type)
{
	struct sk_buff *prev_tail;
	struct net_device *ldev;
	int end, offset, err;

	/* inet_frag_queue_* functions use skb->cb; see struct ipfrag_skb_cb
	 * in inet_fragment.c
	 */
	BUILD_BUG_ON(sizeof(struct lowpan_802154_cb) > sizeof(struct inet_skb_parm));
	BUILD_BUG_ON(sizeof(struct lowpan_802154_cb) > sizeof(struct inet6_skb_parm));

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

	offset = lowpan_802154_cb(skb)->d_offset << 3;
	end = lowpan_802154_cb(skb)->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.flags & INET_FRAG_LAST_IN) && end != fq->q.len))
			goto err;
		fq->q.flags |= INET_FRAG_LAST_IN;
		fq->q.len = end;
	} else {
		if (end > fq->q.len) {
			/* Some bits beyond end -> corruption. */
			if (fq->q.flags & INET_FRAG_LAST_IN)
				goto err;
			fq->q.len = end;
		}
	}

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

	prev_tail = fq->q.fragments_tail;
	err = inet_frag_queue_insert(&fq->q, skb, offset, end);
	if (err)
		goto err;

	fq->q.stamp = skb->tstamp;
	if (frag_type == LOWPAN_DISPATCH_FRAG1)
		fq->q.flags |= INET_FRAG_FIRST_IN;

	fq->q.meat += skb->len;
	add_frag_mem_limit(fq->q.net, skb->truesize);

	if (fq->q.flags == (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, skb, prev_tail, ldev);
		skb->_skb_refdst = orefdst;
		return res;
	}
	skb_dst_drop(skb);

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

/*	Check if this packet is complete.
 *
 *	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 *skb,
			     struct sk_buff *prev_tail, struct net_device *ldev)
{
	void *reasm_data;

	inet_frag_kill(&fq->q);

	reasm_data = inet_frag_reasm_prepare(&fq->q, skb, prev_tail);
	if (!reasm_data)
		goto out_oom;
	inet_frag_reasm_finish(&fq->q, skb, reasm_data);

	skb->dev = ldev;
	skb->tstamp = fq->q.stamp;
	fq->q.rb_fragments = RB_ROOT;
	fq->q.fragments_tail = NULL;
	fq->q.last_run_head = NULL;

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

static int lowpan_frag_rx_handlers_result(struct sk_buff *skb,
					  lowpan_rx_result res)
{
	switch (res) {
	case RX_QUEUED:
		return NET_RX_SUCCESS;
	case RX_CONTINUE:
		/* nobody cared about this packet */
		net_warn_ratelimited("%s: received unknown dispatch\n",
				     __func__);

		/* fall-through */
	default:
		/* all others failure */
		return NET_RX_DROP;
	}
}

static lowpan_rx_result lowpan_frag_rx_h_iphc(struct sk_buff *skb)
{
	int ret;

	if (!lowpan_is_iphc(*skb_network_header(skb)))
		return RX_CONTINUE;

	ret = lowpan_iphc_decompress(skb);
	if (ret < 0)
		return RX_DROP;

	return RX_QUEUED;
}

static int lowpan_invoke_frag_rx_handlers(struct sk_buff *skb)
{
	lowpan_rx_result res;

#define CALL_RXH(rxh)			\
	do {				\
		res = rxh(skb);	\
		if (res != RX_CONTINUE)	\
			goto rxh_next;	\
	} while (0)

	/* likely at first */
	CALL_RXH(lowpan_frag_rx_h_iphc);
	CALL_RXH(lowpan_rx_h_ipv6);

rxh_next:
	return lowpan_frag_rx_handlers_result(skb, res);
#undef CALL_RXH
}

#define LOWPAN_FRAG_DGRAM_SIZE_HIGH_MASK	0x07
#define LOWPAN_FRAG_DGRAM_SIZE_HIGH_SHIFT	8

static int lowpan_get_cb(struct sk_buff *skb, u8 frag_type,
			 struct lowpan_802154_cb *cb)
{
	bool fail;
	u8 high = 0, low = 0;
	__be16 d_tag = 0;

	fail = lowpan_fetch_skb(skb, &high, 1);
	fail |= lowpan_fetch_skb(skb, &low, 1);
	/* remove the dispatch value and use first three bits as high value
	 * for the datagram size
	 */
	cb->d_size = (high & LOWPAN_FRAG_DGRAM_SIZE_HIGH_MASK) <<
		LOWPAN_FRAG_DGRAM_SIZE_HIGH_SHIFT | low;
	fail |= lowpan_fetch_skb(skb, &d_tag, 2);
	cb->d_tag = ntohs(d_tag);

	if (frag_type == LOWPAN_DISPATCH_FRAGN) {
		fail |= lowpan_fetch_skb(skb, &cb->d_offset, 1);
	} else {
		skb_reset_network_header(skb);
		cb->d_offset = 0;
		/* check if datagram_size has ipv6hdr on FRAG1 */
		fail |= cb->d_size < sizeof(struct ipv6hdr);
		/* check if we can dereference the dispatch value */
		fail |= !skb->len;
	}

	if (unlikely(fail))
		return -EIO;

	return 0;
}

int lowpan_frag_rcv(struct sk_buff *skb, u8 frag_type)
{
	struct lowpan_frag_queue *fq;
	struct net *net = dev_net(skb->dev);
	struct lowpan_802154_cb *cb = lowpan_802154_cb(skb);
	struct ieee802154_hdr hdr = {};
	int err;

	if (ieee802154_hdr_peek_addrs(skb, &hdr) < 0)
		goto err;

	err = lowpan_get_cb(skb, frag_type, cb);
	if (err < 0)
		goto err;

	if (frag_type == LOWPAN_DISPATCH_FRAG1) {
		err = lowpan_invoke_frag_rx_handlers(skb);
		if (err == NET_RX_DROP)
			goto err;
	}

	if (cb->d_size > IPV6_MIN_MTU) {
		net_warn_ratelimited("lowpan_frag_rcv: datagram size exceeds MTU\n");
		goto err;
	}

	fq = fq_find(net, cb, &hdr.source, &hdr.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);
		return ret;
	}

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

#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(unsigned long),
		.mode		= 0644,
		.proc_handler	= proc_doulongvec_minmax,
		.extra1		= &init_net.ieee802154_lowpan.frags.low_thresh
	},
	{
		.procname	= "6lowpanfrag_low_thresh",
		.data		= &init_net.ieee802154_lowpan.frags.low_thresh,
		.maxlen		= sizeof(unsigned long),
		.mode		= 0644,
		.proc_handler	= proc_doulongvec_minmax,
		.extra2		= &init_net.ieee802154_lowpan.frags.high_thresh
	},
	{
		.procname	= "6lowpanfrag_time",
		.data		= &init_net.ieee802154_lowpan.frags.timeout,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_jiffies,
	},
	{ }
};

/* secret interval has been deprecated */
static int lowpan_frags_secret_interval_unused;
static struct ctl_table lowpan_frags_ctl_table[] = {
	{
		.procname	= "6lowpanfrag_secret_interval",
		.data		= &lowpan_frags_secret_interval_unused,
		.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;
	struct netns_ieee802154_lowpan *ieee802154_lowpan =
		net_ieee802154_lowpan(net);

	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 = &ieee802154_lowpan->frags.high_thresh;
		table[0].extra1 = &ieee802154_lowpan->frags.low_thresh;
		table[1].data = &ieee802154_lowpan->frags.low_thresh;
		table[1].extra2 = &ieee802154_lowpan->frags.high_thresh;
		table[2].data = &ieee802154_lowpan->frags.timeout;

		/* 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;

	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;
	struct netns_ieee802154_lowpan *ieee802154_lowpan =
		net_ieee802154_lowpan(net);

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

static struct ctl_table_header *lowpan_ctl_header;

static int __init 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 __init 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)
{
	struct netns_ieee802154_lowpan *ieee802154_lowpan =
		net_ieee802154_lowpan(net);
	int res;

	ieee802154_lowpan->frags.high_thresh = IPV6_FRAG_HIGH_THRESH;
	ieee802154_lowpan->frags.low_thresh = IPV6_FRAG_LOW_THRESH;
	ieee802154_lowpan->frags.timeout = IPV6_FRAG_TIMEOUT;
	ieee802154_lowpan->frags.f = &lowpan_frags;

	res = inet_frags_init_net(&ieee802154_lowpan->frags);
	if (res < 0)
		return res;
	res = lowpan_frags_ns_sysctl_register(net);
	if (res < 0)
		inet_frags_exit_net(&ieee802154_lowpan->frags);
	return res;
}

static void __net_exit lowpan_frags_exit_net(struct net *net)
{
	struct netns_ieee802154_lowpan *ieee802154_lowpan =
		net_ieee802154_lowpan(net);

	lowpan_frags_ns_sysctl_unregister(net);
	inet_frags_exit_net(&ieee802154_lowpan->frags);
}

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

static u32 lowpan_key_hashfn(const void *data, u32 len, u32 seed)
{
	return jhash2(data,
		      sizeof(struct frag_lowpan_compare_key) / sizeof(u32), seed);
}

static u32 lowpan_obj_hashfn(const void *data, u32 len, u32 seed)
{
	const struct inet_frag_queue *fq = data;

	return jhash2((const u32 *)&fq->key,
		      sizeof(struct frag_lowpan_compare_key) / sizeof(u32), seed);
}

static int lowpan_obj_cmpfn(struct rhashtable_compare_arg *arg, const void *ptr)
{
	const struct frag_lowpan_compare_key *key = arg->key;
	const struct inet_frag_queue *fq = ptr;

	return !!memcmp(&fq->key, key, sizeof(*key));
}

static const struct rhashtable_params lowpan_rhash_params = {
	.head_offset		= offsetof(struct inet_frag_queue, node),
	.hashfn			= lowpan_key_hashfn,
	.obj_hashfn		= lowpan_obj_hashfn,
	.obj_cmpfn		= lowpan_obj_cmpfn,
	.automatic_shrinking	= true,
};

int __init lowpan_net_frag_init(void)
{
	int ret;

	lowpan_frags.constructor = lowpan_frag_init;
	lowpan_frags.destructor = NULL;
	lowpan_frags.qsize = sizeof(struct frag_queue);
	lowpan_frags.frag_expire = lowpan_frag_expire;
	lowpan_frags.frags_cache_name = lowpan_frags_cache_name;
	lowpan_frags.rhash_params = lowpan_rhash_params;
	ret = inet_frags_init(&lowpan_frags);
	if (ret)
		goto out;

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

	ret = register_pernet_subsys(&lowpan_frags_ops);
	if (ret)
		goto err_pernet;
out:
	return ret;
err_pernet:
	lowpan_frags_sysctl_unregister();
err_sysctl:
	inet_frags_fini(&lowpan_frags);
	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
	1	// SPDX-License-Identifier: GPL-2.0-or-later
	2	/* 6LoWPAN fragment reassembly
	3	*
	4	* Authors:
	5	* Alexander Aring <aar@pengutronix.de>
	6	*
	7	* Based on: net/ipv6/reassembly.c
	8	*/
	9
	10	#define pr_fmt(fmt) "6LoWPAN: " fmt
	11
	12	#include <linux/net.h>
	13	#include <linux/list.h>
	14	#include <linux/netdevice.h>
	15	#include <linux/random.h>
	16	#include <linux/jhash.h>
	17	#include <linux/skbuff.h>
	18	#include <linux/slab.h>
	19	#include <linux/export.h>
	20
	21	#include <net/ieee802154_netdev.h>
	22	#include <net/6lowpan.h>
	23	#include <net/ipv6_frag.h>
	24	#include <net/inet_frag.h>
	25	#include <net/ip.h>
	26
	27	#include "6lowpan_i.h"
	28
	29	static const char lowpan_frags_cache_name[] = "lowpan-frags";
	30
	31	static struct inet_frags lowpan_frags;
	32
	33	static int lowpan_frag_reasm(struct lowpan_frag_queue fq, struct sk_buff skb,
	34	struct sk_buff prev, struct net_device ldev);
	35
	36	static void lowpan_frag_init(struct inet_frag_queue q, const void a)
	37	{
	38	const struct frag_lowpan_compare_key *key = a;
	39
	40	BUILD_BUG_ON(sizeof(*key) > sizeof(q->key));
	41	memcpy(&q->key, key, sizeof(*key));
	42	}
	43
	44	static void lowpan_frag_expire(struct timer_list *t)
	45	{
	46	struct inet_frag_queue *frag = from_timer(frag, t, timer);
	47	struct frag_queue *fq;
	48
	49	fq = container_of(frag, struct frag_queue, q);
	50
	51	spin_lock(&fq->q.lock);
	52
	53	if (fq->q.flags & INET_FRAG_COMPLETE)
	54	goto out;
	55
	56	inet_frag_kill(&fq->q);
	57	out:
	58	spin_unlock(&fq->q.lock);
	59	inet_frag_put(&fq->q);
	60	}
	61
	62	static inline struct lowpan_frag_queue *
	63	fq_find(struct net net, const struct lowpan_802154_cb cb,
	64	const struct ieee802154_addr *src,
	65	const struct ieee802154_addr *dst)
	66	{
	67	struct netns_ieee802154_lowpan *ieee802154_lowpan =
	68	net_ieee802154_lowpan(net);
	69	struct frag_lowpan_compare_key key = {};
	70	struct inet_frag_queue *q;
	71
	72	key.tag = cb->d_tag;
	73	key.d_size = cb->d_size;
	74	key.src = *src;
	75	key.dst = *dst;
	76
	77	q = inet_frag_find(&ieee802154_lowpan->frags, &key);
	78	if (!q)
	79	return NULL;
	80
	81	return container_of(q, struct lowpan_frag_queue, q);
	82	}
	83
	84	static int lowpan_frag_queue(struct lowpan_frag_queue *fq,
	85	struct sk_buff *skb, u8 frag_type)
	86	{
	87	struct sk_buff *prev_tail;
	88	struct net_device *ldev;
	89	int end, offset, err;
	90
	91	/* inet_frag_queue_* functions use skb->cb; see struct ipfrag_skb_cb
	92	* in inet_fragment.c
	93	*/
	94	BUILD_BUG_ON(sizeof(struct lowpan_802154_cb) > sizeof(struct inet_skb_parm));
	95	BUILD_BUG_ON(sizeof(struct lowpan_802154_cb) > sizeof(struct inet6_skb_parm));
	96
	97	if (fq->q.flags & INET_FRAG_COMPLETE)
	98	goto err;
	99
	100	offset = lowpan_802154_cb(skb)->d_offset << 3;
	101	end = lowpan_802154_cb(skb)->d_size;
	102
	103	/* Is this the final fragment? */
	104	if (offset + skb->len == end) {
	105	/* If we already have some bits beyond end
	106	* or have different end, the segment is corrupted.
	107	*/
	108	if (end < fq->q.len \|\|
	109	((fq->q.flags & INET_FRAG_LAST_IN) && end != fq->q.len))
	110	goto err;
	111	fq->q.flags \|= INET_FRAG_LAST_IN;
	112	fq->q.len = end;
	113	} else {
	114	if (end > fq->q.len) {
	115	/* Some bits beyond end -> corruption. */
	116	if (fq->q.flags & INET_FRAG_LAST_IN)
	117	goto err;
	118	fq->q.len = end;
	119	}
	120	}
	121
	122	ldev = skb->dev;
	123	if (ldev)
	124	skb->dev = NULL;
	125	barrier();
	126
	127	prev_tail = fq->q.fragments_tail;
	128	err = inet_frag_queue_insert(&fq->q, skb, offset, end);
	129	if (err)
	130	goto err;
	131
	132	fq->q.stamp = skb->tstamp;
	133	if (frag_type == LOWPAN_DISPATCH_FRAG1)
	134	fq->q.flags \|= INET_FRAG_FIRST_IN;
	135
	136	fq->q.meat += skb->len;
	137	add_frag_mem_limit(fq->q.net, skb->truesize);
	138
	139	if (fq->q.flags == (INET_FRAG_FIRST_IN \| INET_FRAG_LAST_IN) &&
	140	fq->q.meat == fq->q.len) {
	141	int res;
	142	unsigned long orefdst = skb->_skb_refdst;
	143
	144	skb->_skb_refdst = 0UL;
	145	res = lowpan_frag_reasm(fq, skb, prev_tail, ldev);
	146	skb->_skb_refdst = orefdst;
	147	return res;
	148	}
	149	skb_dst_drop(skb);
	150
	151	return -1;
	152	err:
	153	kfree_skb(skb);
	154	return -1;
	155	}
	156
	157	/* Check if this packet is complete.
	158	*
	159	* It is called with locked fq, and caller must check that
	160	* queue is eligible for reassembly i.e. it is not COMPLETE,
	161	* the last and the first frames arrived and all the bits are here.
	162	*/
	163	static int lowpan_frag_reasm(struct lowpan_frag_queue fq, struct sk_buff skb,
	164	struct sk_buff prev_tail, struct net_device ldev)
	165	{
	166	void *reasm_data;
	167
	168	inet_frag_kill(&fq->q);
	169
	170	reasm_data = inet_frag_reasm_prepare(&fq->q, skb, prev_tail);
	171	if (!reasm_data)
	172	goto out_oom;
	173	inet_frag_reasm_finish(&fq->q, skb, reasm_data);
	174
	175	skb->dev = ldev;
	176	skb->tstamp = fq->q.stamp;
	177	fq->q.rb_fragments = RB_ROOT;
	178	fq->q.fragments_tail = NULL;
	179	fq->q.last_run_head = NULL;
	180
	181	return 1;
	182	out_oom:
	183	net_dbg_ratelimited("lowpan_frag_reasm: no memory for reassembly\n");
	184	return -1;
	185	}
	186
	187	static int lowpan_frag_rx_handlers_result(struct sk_buff *skb,
	188	lowpan_rx_result res)
	189	{
	190	switch (res) {
	191	case RX_QUEUED:
	192	return NET_RX_SUCCESS;
	193	case RX_CONTINUE:
	194	/* nobody cared about this packet */
	195	net_warn_ratelimited("%s: received unknown dispatch\n",
	196	__func__);
	197
	198	/* fall-through */
	199	default:
	200	/* all others failure */
	201	return NET_RX_DROP;
	202	}
	203	}
	204
	205	static lowpan_rx_result lowpan_frag_rx_h_iphc(struct sk_buff *skb)
	206	{
	207	int ret;
	208
	209	if (!lowpan_is_iphc(*skb_network_header(skb)))
	210	return RX_CONTINUE;
	211
	212	ret = lowpan_iphc_decompress(skb);
	213	if (ret < 0)
	214	return RX_DROP;
	215
	216	return RX_QUEUED;
	217	}
	218
	219	static int lowpan_invoke_frag_rx_handlers(struct sk_buff *skb)
	220	{
	221	lowpan_rx_result res;
	222
	223	#define CALL_RXH(rxh) \
	224	do { \
	225	res = rxh(skb); \
	226	if (res != RX_CONTINUE) \
	227	goto rxh_next; \
	228	} while (0)
	229
	230	/* likely at first */
	231	CALL_RXH(lowpan_frag_rx_h_iphc);
	232	CALL_RXH(lowpan_rx_h_ipv6);
	233
	234	rxh_next:
	235	return lowpan_frag_rx_handlers_result(skb, res);
	236	#undef CALL_RXH
	237	}
	238
	239	#define LOWPAN_FRAG_DGRAM_SIZE_HIGH_MASK 0x07
	240	#define LOWPAN_FRAG_DGRAM_SIZE_HIGH_SHIFT 8
	241
	242	static int lowpan_get_cb(struct sk_buff *skb, u8 frag_type,
	243	struct lowpan_802154_cb *cb)
	244	{
	245	bool fail;
	246	u8 high = 0, low = 0;
	247	__be16 d_tag = 0;
	248
	249	fail = lowpan_fetch_skb(skb, &high, 1);
	250	fail \|= lowpan_fetch_skb(skb, &low, 1);
	251	/* remove the dispatch value and use first three bits as high value
	252	* for the datagram size
	253	*/
	254	cb->d_size = (high & LOWPAN_FRAG_DGRAM_SIZE_HIGH_MASK) <<
	255	LOWPAN_FRAG_DGRAM_SIZE_HIGH_SHIFT \| low;
	256	fail \|= lowpan_fetch_skb(skb, &d_tag, 2);
	257	cb->d_tag = ntohs(d_tag);
	258
	259	if (frag_type == LOWPAN_DISPATCH_FRAGN) {
	260	fail \|= lowpan_fetch_skb(skb, &cb->d_offset, 1);
	261	} else {
	262	skb_reset_network_header(skb);
	263	cb->d_offset = 0;
	264	/* check if datagram_size has ipv6hdr on FRAG1 */
	265	fail \|= cb->d_size < sizeof(struct ipv6hdr);
	266	/* check if we can dereference the dispatch value */
	267	fail \|= !skb->len;
	268	}
	269
	270	if (unlikely(fail))
	271	return -EIO;
	272
	273	return 0;
	274	}
	275
	276	int lowpan_frag_rcv(struct sk_buff *skb, u8 frag_type)
	277	{
	278	struct lowpan_frag_queue *fq;
	279	struct net *net = dev_net(skb->dev);
	280	struct lowpan_802154_cb *cb = lowpan_802154_cb(skb);
	281	struct ieee802154_hdr hdr = {};
	282	int err;
	283
	284	if (ieee802154_hdr_peek_addrs(skb, &hdr) < 0)
	285	goto err;
	286
	287	err = lowpan_get_cb(skb, frag_type, cb);
	288	if (err < 0)
	289	goto err;
	290
	291	if (frag_type == LOWPAN_DISPATCH_FRAG1) {
	292	err = lowpan_invoke_frag_rx_handlers(skb);
	293	if (err == NET_RX_DROP)
	294	goto err;
	295	}
	296
	297	if (cb->d_size > IPV6_MIN_MTU) {
	298	net_warn_ratelimited("lowpan_frag_rcv: datagram size exceeds MTU\n");
	299	goto err;
	300	}
	301
	302	fq = fq_find(net, cb, &hdr.source, &hdr.dest);
	303	if (fq != NULL) {
	304	int ret;
	305
	306	spin_lock(&fq->q.lock);
	307	ret = lowpan_frag_queue(fq, skb, frag_type);
	308	spin_unlock(&fq->q.lock);
	309
	310	inet_frag_put(&fq->q);
	311	return ret;
	312	}
	313
	314	err:
	315	kfree_skb(skb);
	316	return -1;
	317	}
	318
	319	#ifdef CONFIG_SYSCTL
	320
	321	static struct ctl_table lowpan_frags_ns_ctl_table[] = {
	322	{
	323	.procname = "6lowpanfrag_high_thresh",
	324	.data = &init_net.ieee802154_lowpan.frags.high_thresh,
	325	.maxlen = sizeof(unsigned long),
	326	.mode = 0644,
	327	.proc_handler = proc_doulongvec_minmax,
	328	.extra1 = &init_net.ieee802154_lowpan.frags.low_thresh
	329	},
	330	{
	331	.procname = "6lowpanfrag_low_thresh",
	332	.data = &init_net.ieee802154_lowpan.frags.low_thresh,
	333	.maxlen = sizeof(unsigned long),
	334	.mode = 0644,
	335	.proc_handler = proc_doulongvec_minmax,
	336	.extra2 = &init_net.ieee802154_lowpan.frags.high_thresh
	337	},
	338	{
	339	.procname = "6lowpanfrag_time",
	340	.data = &init_net.ieee802154_lowpan.frags.timeout,
	341	.maxlen = sizeof(int),
	342	.mode = 0644,
	343	.proc_handler = proc_dointvec_jiffies,
	344	},
	345	{ }
	346	};
	347
	348	/* secret interval has been deprecated */
	349	static int lowpan_frags_secret_interval_unused;
	350	static struct ctl_table lowpan_frags_ctl_table[] = {
	351	{
	352	.procname = "6lowpanfrag_secret_interval",
	353	.data = &lowpan_frags_secret_interval_unused,
	354	.maxlen = sizeof(int),
	355	.mode = 0644,
	356	.proc_handler = proc_dointvec_jiffies,
	357	},
	358	{ }
	359	};
	360
	361	static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
	362	{
	363	struct ctl_table *table;
	364	struct ctl_table_header *hdr;
	365	struct netns_ieee802154_lowpan *ieee802154_lowpan =
	366	net_ieee802154_lowpan(net);
	367
	368	table = lowpan_frags_ns_ctl_table;
	369	if (!net_eq(net, &init_net)) {
	370	table = kmemdup(table, sizeof(lowpan_frags_ns_ctl_table),
	371	GFP_KERNEL);
	372	if (table == NULL)
	373	goto err_alloc;
	374
	375	table[0].data = &ieee802154_lowpan->frags.high_thresh;
	376	table[0].extra1 = &ieee802154_lowpan->frags.low_thresh;
	377	table[1].data = &ieee802154_lowpan->frags.low_thresh;
	378	table[1].extra2 = &ieee802154_lowpan->frags.high_thresh;
	379	table[2].data = &ieee802154_lowpan->frags.timeout;
	380
	381	/* Don't export sysctls to unprivileged users */
	382	if (net->user_ns != &init_user_ns)
	383	table[0].procname = NULL;
	384	}
	385
	386	hdr = register_net_sysctl(net, "net/ieee802154/6lowpan", table);
	387	if (hdr == NULL)
	388	goto err_reg;
	389
	390	ieee802154_lowpan->sysctl.frags_hdr = hdr;
	391	return 0;
	392
	393	err_reg:
	394	if (!net_eq(net, &init_net))
	395	kfree(table);
	396	err_alloc:
	397	return -ENOMEM;
	398	}
	399
	400	static void __net_exit lowpan_frags_ns_sysctl_unregister(struct net *net)
	401	{
	402	struct ctl_table *table;
	403	struct netns_ieee802154_lowpan *ieee802154_lowpan =
	404	net_ieee802154_lowpan(net);
	405
	406	table = ieee802154_lowpan->sysctl.frags_hdr->ctl_table_arg;
	407	unregister_net_sysctl_table(ieee802154_lowpan->sysctl.frags_hdr);
	408	if (!net_eq(net, &init_net))
	409	kfree(table);
	410	}
	411
	412	static struct ctl_table_header *lowpan_ctl_header;
	413
	414	static int __init lowpan_frags_sysctl_register(void)
	415	{
	416	lowpan_ctl_header = register_net_sysctl(&init_net,
	417	"net/ieee802154/6lowpan",
	418	lowpan_frags_ctl_table);
	419	return lowpan_ctl_header == NULL ? -ENOMEM : 0;
	420	}
	421
	422	static void lowpan_frags_sysctl_unregister(void)
	423	{
	424	unregister_net_sysctl_table(lowpan_ctl_header);
	425	}
	426	#else
	427	static inline int lowpan_frags_ns_sysctl_register(struct net *net)
	428	{
	429	return 0;
	430	}
	431
	432	static inline void lowpan_frags_ns_sysctl_unregister(struct net *net)
	433	{
	434	}
	435
	436	static inline int __init lowpan_frags_sysctl_register(void)
	437	{
	438	return 0;
	439	}
	440
	441	static inline void lowpan_frags_sysctl_unregister(void)
	442	{
	443	}
	444	#endif
	445
	446	static int __net_init lowpan_frags_init_net(struct net *net)
	447	{
	448	struct netns_ieee802154_lowpan *ieee802154_lowpan =
	449	net_ieee802154_lowpan(net);
	450	int res;
	451
	452	ieee802154_lowpan->frags.high_thresh = IPV6_FRAG_HIGH_THRESH;
	453	ieee802154_lowpan->frags.low_thresh = IPV6_FRAG_LOW_THRESH;
	454	ieee802154_lowpan->frags.timeout = IPV6_FRAG_TIMEOUT;
	455	ieee802154_lowpan->frags.f = &lowpan_frags;
	456
	457	res = inet_frags_init_net(&ieee802154_lowpan->frags);
	458	if (res < 0)
	459	return res;
	460	res = lowpan_frags_ns_sysctl_register(net);
	461	if (res < 0)
	462	inet_frags_exit_net(&ieee802154_lowpan->frags);
	463	return res;
	464	}
	465
	466	static void __net_exit lowpan_frags_exit_net(struct net *net)
	467	{
	468	struct netns_ieee802154_lowpan *ieee802154_lowpan =
	469	net_ieee802154_lowpan(net);
	470
	471	lowpan_frags_ns_sysctl_unregister(net);
	472	inet_frags_exit_net(&ieee802154_lowpan->frags);
	473	}
	474
	475	static struct pernet_operations lowpan_frags_ops = {
	476	.init = lowpan_frags_init_net,
	477	.exit = lowpan_frags_exit_net,
	478	};
	479
	480	static u32 lowpan_key_hashfn(const void *data, u32 len, u32 seed)
	481	{
	482	return jhash2(data,
	483	sizeof(struct frag_lowpan_compare_key) / sizeof(u32), seed);
	484	}
	485
	486	static u32 lowpan_obj_hashfn(const void *data, u32 len, u32 seed)
	487	{
	488	const struct inet_frag_queue *fq = data;
	489
	490	return jhash2((const u32 *)&fq->key,
	491	sizeof(struct frag_lowpan_compare_key) / sizeof(u32), seed);
	492	}
	493
	494	static int lowpan_obj_cmpfn(struct rhashtable_compare_arg arg, const void ptr)
	495	{
	496	const struct frag_lowpan_compare_key *key = arg->key;
	497	const struct inet_frag_queue *fq = ptr;
	498
	499	return !!memcmp(&fq->key, key, sizeof(*key));
	500	}
	501
	502	static const struct rhashtable_params lowpan_rhash_params = {
	503	.head_offset = offsetof(struct inet_frag_queue, node),
	504	.hashfn = lowpan_key_hashfn,
	505	.obj_hashfn = lowpan_obj_hashfn,
	506	.obj_cmpfn = lowpan_obj_cmpfn,
	507	.automatic_shrinking = true,
	508	};
	509
	510	int __init lowpan_net_frag_init(void)
	511	{
	512	int ret;
	513
	514	lowpan_frags.constructor = lowpan_frag_init;
	515	lowpan_frags.destructor = NULL;
	516	lowpan_frags.qsize = sizeof(struct frag_queue);
	517	lowpan_frags.frag_expire = lowpan_frag_expire;
	518	lowpan_frags.frags_cache_name = lowpan_frags_cache_name;
	519	lowpan_frags.rhash_params = lowpan_rhash_params;
	520	ret = inet_frags_init(&lowpan_frags);
	521	if (ret)
	522	goto out;
	523
	524	ret = lowpan_frags_sysctl_register();
	525	if (ret)
	526	goto err_sysctl;
	527
	528	ret = register_pernet_subsys(&lowpan_frags_ops);
	529	if (ret)
	530	goto err_pernet;
	531	out:
	532	return ret;
	533	err_pernet:
	534	lowpan_frags_sysctl_unregister();
	535	err_sysctl:
	536	inet_frags_fini(&lowpan_frags);
	537	return ret;
	538	}
	539
	540	void lowpan_net_frag_exit(void)
	541	{
	542	inet_frags_fini(&lowpan_frags);
	543	lowpan_frags_sysctl_unregister();
	544	unregister_pernet_subsys(&lowpan_frags_ops);
	545	}