[deliverable/linux.git] / net / ipv4 / udp_offload.c

/*
 *	IPV4 GSO/GRO offload support
 *	Linux INET implementation
 *
 *	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.
 *
 *	UDPv4 GSO support
 */

#include <linux/skbuff.h>
#include <net/udp.h>
#include <net/protocol.h>

static DEFINE_SPINLOCK(udp_offload_lock);
static struct udp_offload_priv __rcu *udp_offload_base __read_mostly;

#define udp_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&udp_offload_lock))

struct udp_offload_priv {
	struct udp_offload	*offload;
	struct rcu_head		rcu;
	struct udp_offload_priv __rcu *next;
};

struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
				       netdev_features_t features)
{
	struct sk_buff *segs = ERR_PTR(-EINVAL);
	u16 mac_offset = skb->mac_header;
	int mac_len = skb->mac_len;
	int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
	__be16 protocol = skb->protocol;
	netdev_features_t enc_features;
	int udp_offset, outer_hlen;
	unsigned int oldlen;
	bool need_csum;

	oldlen = (u16)~skb->len;

	if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
		goto out;

	skb->encapsulation = 0;
	__skb_pull(skb, tnl_hlen);
	skb_reset_mac_header(skb);
	skb_set_network_header(skb, skb_inner_network_offset(skb));
	skb->mac_len = skb_inner_network_offset(skb);
	skb->protocol = htons(ETH_P_TEB);

	need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM);
	if (need_csum)
		skb->encap_hdr_csum = 1;

	/* segment inner packet. */
	enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
	segs = skb_mac_gso_segment(skb, enc_features);
	if (IS_ERR_OR_NULL(segs)) {
		skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
				     mac_len);
		goto out;
	}

	outer_hlen = skb_tnl_header_len(skb);
	udp_offset = outer_hlen - tnl_hlen;
	skb = segs;
	do {
		struct udphdr *uh;
		int len;

		skb_reset_inner_headers(skb);
		skb->encapsulation = 1;

		skb->mac_len = mac_len;

		skb_push(skb, outer_hlen);
		skb_reset_mac_header(skb);
		skb_set_network_header(skb, mac_len);
		skb_set_transport_header(skb, udp_offset);
		len = skb->len - udp_offset;
		uh = udp_hdr(skb);
		uh->len = htons(len);

		if (need_csum) {
			__be32 delta = htonl(oldlen + len);

			uh->check = ~csum_fold((__force __wsum)
					       ((__force u32)uh->check +
						(__force u32)delta));
			uh->check = gso_make_checksum(skb, ~uh->check);

			if (uh->check == 0)
				uh->check = CSUM_MANGLED_0;
		}

		skb->protocol = protocol;
	} while ((skb = skb->next));
out:
	return segs;
}

static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
					 netdev_features_t features)
{
	struct sk_buff *segs = ERR_PTR(-EINVAL);
	unsigned int mss;
	__wsum csum;
	struct udphdr *uh;
	struct iphdr *iph;

	if (skb->encapsulation &&
	    (skb_shinfo(skb)->gso_type &
	     (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
		segs = skb_udp_tunnel_segment(skb, features);
		goto out;
	}

	if (!pskb_may_pull(skb, sizeof(struct udphdr)))
		goto out;

	mss = skb_shinfo(skb)->gso_size;
	if (unlikely(skb->len <= mss))
		goto out;

	if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
		/* Packet is from an untrusted source, reset gso_segs. */
		int type = skb_shinfo(skb)->gso_type;

		if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY |
				      SKB_GSO_UDP_TUNNEL |
				      SKB_GSO_UDP_TUNNEL_CSUM |
				      SKB_GSO_IPIP |
				      SKB_GSO_GRE | SKB_GSO_GRE_CSUM |
				      SKB_GSO_MPLS) ||
			     !(type & (SKB_GSO_UDP))))
			goto out;

		skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);

		segs = NULL;
		goto out;
	}

	/* Do software UFO. Complete and fill in the UDP checksum as
	 * HW cannot do checksum of UDP packets sent as multiple
	 * IP fragments.
	 */

	uh = udp_hdr(skb);
	iph = ip_hdr(skb);

	uh->check = 0;
	csum = skb_checksum(skb, 0, skb->len, 0);
	uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum);
	if (uh->check == 0)
		uh->check = CSUM_MANGLED_0;

	skb->ip_summed = CHECKSUM_NONE;

	/* Fragment the skb. IP headers of the fragments are updated in
	 * inet_gso_segment()
	 */
	segs = skb_segment(skb, features);
out:
	return segs;
}

int udp_add_offload(struct udp_offload *uo)
{
	struct udp_offload_priv *new_offload = kzalloc(sizeof(*new_offload), GFP_ATOMIC);

	if (!new_offload)
		return -ENOMEM;

	new_offload->offload = uo;

	spin_lock(&udp_offload_lock);
	new_offload->next = udp_offload_base;
	rcu_assign_pointer(udp_offload_base, new_offload);
	spin_unlock(&udp_offload_lock);

	return 0;
}
EXPORT_SYMBOL(udp_add_offload);

static void udp_offload_free_routine(struct rcu_head *head)
{
	struct udp_offload_priv *ou_priv = container_of(head, struct udp_offload_priv, rcu);
	kfree(ou_priv);
}

void udp_del_offload(struct udp_offload *uo)
{
	struct udp_offload_priv __rcu **head = &udp_offload_base;
	struct udp_offload_priv *uo_priv;

	spin_lock(&udp_offload_lock);

	uo_priv = udp_deref_protected(*head);
	for (; uo_priv != NULL;
	     uo_priv = udp_deref_protected(*head)) {
		if (uo_priv->offload == uo) {
			rcu_assign_pointer(*head,
					   udp_deref_protected(uo_priv->next));
			goto unlock;
		}
		head = &uo_priv->next;
	}
	pr_warn("udp_del_offload: didn't find offload for port %d\n", ntohs(uo->port));
unlock:
	spin_unlock(&udp_offload_lock);
	if (uo_priv != NULL)
		call_rcu(&uo_priv->rcu, udp_offload_free_routine);
}
EXPORT_SYMBOL(udp_del_offload);

struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb,
				 struct udphdr *uh)
{
	struct udp_offload_priv *uo_priv;
	struct sk_buff *p, **pp = NULL;
	struct udphdr *uh2;
	unsigned int off = skb_gro_offset(skb);
	int flush = 1;

	if (NAPI_GRO_CB(skb)->udp_mark ||
	    (skb->ip_summed != CHECKSUM_PARTIAL &&
	     NAPI_GRO_CB(skb)->csum_cnt == 0 &&
	     !NAPI_GRO_CB(skb)->csum_valid))
		goto out;

	/* mark that this skb passed once through the udp gro layer */
	NAPI_GRO_CB(skb)->udp_mark = 1;

	rcu_read_lock();
	uo_priv = rcu_dereference(udp_offload_base);
	for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
		if (uo_priv->offload->port == uh->dest &&
		    uo_priv->offload->callbacks.gro_receive)
			goto unflush;
	}
	goto out_unlock;

unflush:
	flush = 0;

	for (p = *head; p; p = p->next) {
		if (!NAPI_GRO_CB(p)->same_flow)
			continue;

		uh2 = (struct udphdr   *)(p->data + off);

		/* Match ports and either checksums are either both zero
		 * or nonzero.
		 */
		if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) ||
		    (!uh->check ^ !uh2->check)) {
			NAPI_GRO_CB(p)->same_flow = 0;
			continue;
		}
	}

	skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
	skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
	NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
	pp = uo_priv->offload->callbacks.gro_receive(head, skb);

out_unlock:
	rcu_read_unlock();
out:
	NAPI_GRO_CB(skb)->flush |= flush;
	return pp;
}

static struct sk_buff **udp4_gro_receive(struct sk_buff **head,
					 struct sk_buff *skb)
{
	struct udphdr *uh = udp_gro_udphdr(skb);

	if (unlikely(!uh))
		goto flush;

	/* Don't bother verifying checksum if we're going to flush anyway. */
	if (NAPI_GRO_CB(skb)->flush)
		goto skip;

	if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
						 inet_gro_compute_pseudo))
		goto flush;
	else if (uh->check)
		skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
					     inet_gro_compute_pseudo);
skip:
	return udp_gro_receive(head, skb, uh);

flush:
	NAPI_GRO_CB(skb)->flush = 1;
	return NULL;
}

int udp_gro_complete(struct sk_buff *skb, int nhoff)
{
	struct udp_offload_priv *uo_priv;
	__be16 newlen = htons(skb->len - nhoff);
	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
	int err = -ENOSYS;

	uh->len = newlen;

	rcu_read_lock();

	uo_priv = rcu_dereference(udp_offload_base);
	for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
		if (uo_priv->offload->port == uh->dest &&
		    uo_priv->offload->callbacks.gro_complete)
			break;
	}

	if (uo_priv != NULL) {
		NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
		err = uo_priv->offload->callbacks.gro_complete(skb, nhoff + sizeof(struct udphdr));
	}

	rcu_read_unlock();
	return err;
}

static int udp4_gro_complete(struct sk_buff *skb, int nhoff)
{
	const struct iphdr *iph = ip_hdr(skb);
	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);

	if (uh->check)
		uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
					  iph->daddr, 0);

	return udp_gro_complete(skb, nhoff);
}

static const struct net_offload udpv4_offload = {
	.callbacks = {
		.gso_segment = udp4_ufo_fragment,
		.gro_receive  =	udp4_gro_receive,
		.gro_complete =	udp4_gro_complete,
	},
};

int __init udpv4_offload_init(void)
{
	return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
}
Commit	Line	Data
da5bab07 DB	1	/*
	2	* IPV4 GSO/GRO offload support
	3	* Linux INET implementation
	4	*
	5	* This program is free software; you can redistribute it and/or
	6	* modify it under the terms of the GNU General Public License
	7	* as published by the Free Software Foundation; either version
	8	* 2 of the License, or (at your option) any later version.
	9	*
	10	* UDPv4 GSO support
	11	*/
	12
	13	#include <linux/skbuff.h>
	14	#include <net/udp.h>
	15	#include <net/protocol.h>
	16
b582ef09	17	static DEFINE_SPINLOCK(udp_offload_lock);
a1d0cd8e	18	static struct udp_offload_priv __rcu *udp_offload_base __read_mostly;
b582ef09	19
a664a4f7 SP	20	#define udp_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&udp_offload_lock))
a664a4f7 SP	21
b582ef09 OG	22	struct udp_offload_priv {
	23	struct udp_offload *offload;
	24	struct rcu_head rcu;
	25	struct udp_offload_priv __rcu *next;
	26	};
	27
155e010e TH	28	struct sk_buff skb_udp_tunnel_segment(struct sk_buff skb,
	29	netdev_features_t features)
	30	{
	31	struct sk_buff *segs = ERR_PTR(-EINVAL);
	32	u16 mac_offset = skb->mac_header;
	33	int mac_len = skb->mac_len;
	34	int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
	35	__be16 protocol = skb->protocol;
	36	netdev_features_t enc_features;
	37	int udp_offset, outer_hlen;
	38	unsigned int oldlen;
	39	bool need_csum;
	40
	41	oldlen = (u16)~skb->len;
	42
	43	if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
	44	goto out;
	45
	46	skb->encapsulation = 0;
	47	__skb_pull(skb, tnl_hlen);
	48	skb_reset_mac_header(skb);
	49	skb_set_network_header(skb, skb_inner_network_offset(skb));
	50	skb->mac_len = skb_inner_network_offset(skb);
	51	skb->protocol = htons(ETH_P_TEB);
	52
	53	need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM);
	54	if (need_csum)
	55	skb->encap_hdr_csum = 1;
	56
	57	/* segment inner packet. */
	58	enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
	59	segs = skb_mac_gso_segment(skb, enc_features);
27446442	60	if (IS_ERR_OR_NULL(segs)) {
155e010e TH	61	skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
	62	mac_len);
	63	goto out;
	64	}
	65
	66	outer_hlen = skb_tnl_header_len(skb);
	67	udp_offset = outer_hlen - tnl_hlen;
	68	skb = segs;
	69	do {
	70	struct udphdr *uh;
	71	int len;
	72
	73	skb_reset_inner_headers(skb);
	74	skb->encapsulation = 1;
	75
	76	skb->mac_len = mac_len;
	77
	78	skb_push(skb, outer_hlen);
	79	skb_reset_mac_header(skb);
	80	skb_set_network_header(skb, mac_len);
	81	skb_set_transport_header(skb, udp_offset);
	82	len = skb->len - udp_offset;
	83	uh = udp_hdr(skb);
	84	uh->len = htons(len);
	85
	86	if (need_csum) {
	87	__be32 delta = htonl(oldlen + len);
	88
	89	uh->check = ~csum_fold((__force __wsum)
	90	((__force u32)uh->check +
	91	(__force u32)delta));
	92	uh->check = gso_make_checksum(skb, ~uh->check);
	93
	94	if (uh->check == 0)
	95	uh->check = CSUM_MANGLED_0;
	96	}
	97
	98	skb->protocol = protocol;
	99	} while ((skb = skb->next));
	100	out:
	101	return segs;
	102	}
	103
da5bab07 DB	104	static struct sk_buff udp4_ufo_fragment(struct sk_buff skb,
	105	netdev_features_t features)
	106	{
	107	struct sk_buff *segs = ERR_PTR(-EINVAL);
	108	unsigned int mss;
7a7ffbab	109	__wsum csum;
f71470b3 TH	110	struct udphdr *uh;
f71470b3 TH	111	struct iphdr *iph;
7a7ffbab WCC	112
7a7ffbab WCC	113	if (skb->encapsulation &&
0f4f4ffa TH	114	(skb_shinfo(skb)->gso_type &
0f4f4ffa TH	115	(SKB_GSO_UDP_TUNNEL\|SKB_GSO_UDP_TUNNEL_CSUM))) {
7a7ffbab WCC	116	segs = skb_udp_tunnel_segment(skb, features);
	117	goto out;
	118	}
da5bab07	119
f71470b3 TH	120	if (!pskb_may_pull(skb, sizeof(struct udphdr)))
	121	goto out;
	122
da5bab07 DB	123	mss = skb_shinfo(skb)->gso_size;
	124	if (unlikely(skb->len <= mss))
	125	goto out;
	126
	127	if (skb_gso_ok(skb, features \| NETIF_F_GSO_ROBUST)) {
	128	/* Packet is from an untrusted source, reset gso_segs. */
	129	int type = skb_shinfo(skb)->gso_type;
	130
	131	if (unlikely(type & ~(SKB_GSO_UDP \| SKB_GSO_DODGY \|
	132	SKB_GSO_UDP_TUNNEL \|
0f4f4ffa	133	SKB_GSO_UDP_TUNNEL_CSUM \|
cb32f511	134	SKB_GSO_IPIP \|
4749c09c TH	135	SKB_GSO_GRE \| SKB_GSO_GRE_CSUM \|
4749c09c TH	136	SKB_GSO_MPLS) \|\|
da5bab07 DB	137	!(type & (SKB_GSO_UDP))))
	138	goto out;
	139
	140	skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
	141
	142	segs = NULL;
	143	goto out;
	144	}
	145
7a7ffbab WCC	146	/* Do software UFO. Complete and fill in the UDP checksum as
	147	* HW cannot do checksum of UDP packets sent as multiple
	148	* IP fragments.
	149	*/
f71470b3 TH	150
	151	uh = udp_hdr(skb);
	152	iph = ip_hdr(skb);
	153
	154	uh->check = 0;
	155	csum = skb_checksum(skb, 0, skb->len, 0);
	156	uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum);
	157	if (uh->check == 0)
	158	uh->check = CSUM_MANGLED_0;
	159
7a7ffbab WCC	160	skb->ip_summed = CHECKSUM_NONE;
7a7ffbab WCC	161
da5bab07 DB	162	/* Fragment the skb. IP headers of the fragments are updated in
	163	* inet_gso_segment()
	164	*/
7a7ffbab	165	segs = skb_segment(skb, features);
da5bab07 DB	166	out:
	167	return segs;
	168	}
	169
b582ef09 OG	170	int udp_add_offload(struct udp_offload *uo)
b582ef09 OG	171	{
b5aaab12	172	struct udp_offload_priv new_offload = kzalloc(sizeof(new_offload), GFP_ATOMIC);
b582ef09 OG	173
	174	if (!new_offload)
	175	return -ENOMEM;
	176
	177	new_offload->offload = uo;
	178
	179	spin_lock(&udp_offload_lock);
a664a4f7 SP	180	new_offload->next = udp_offload_base;
a664a4f7 SP	181	rcu_assign_pointer(udp_offload_base, new_offload);
b582ef09 OG	182	spin_unlock(&udp_offload_lock);
	183
	184	return 0;
	185	}
	186	EXPORT_SYMBOL(udp_add_offload);
	187
	188	static void udp_offload_free_routine(struct rcu_head *head)
	189	{
	190	struct udp_offload_priv *ou_priv = container_of(head, struct udp_offload_priv, rcu);
	191	kfree(ou_priv);
	192	}
	193
	194	void udp_del_offload(struct udp_offload *uo)
	195	{
	196	struct udp_offload_priv __rcu **head = &udp_offload_base;
	197	struct udp_offload_priv *uo_priv;
	198
	199	spin_lock(&udp_offload_lock);
	200
a664a4f7	201	uo_priv = udp_deref_protected(*head);
b582ef09	202	for (; uo_priv != NULL;
a664a4f7	203	uo_priv = udp_deref_protected(*head)) {
b582ef09	204	if (uo_priv->offload == uo) {
a664a4f7 SP	205	rcu_assign_pointer(*head,
a664a4f7 SP	206	udp_deref_protected(uo_priv->next));
b582ef09 OG	207	goto unlock;
	208	}
	209	head = &uo_priv->next;
	210	}
a1d0cd8e	211	pr_warn("udp_del_offload: didn't find offload for port %d\n", ntohs(uo->port));
b582ef09 OG	212	unlock:
	213	spin_unlock(&udp_offload_lock);
	214	if (uo_priv != NULL)
	215	call_rcu(&uo_priv->rcu, udp_offload_free_routine);
	216	}
	217	EXPORT_SYMBOL(udp_del_offload);
	218
57c67ff4 TH	219	struct sk_buff udp_gro_receive(struct sk_buff head, struct sk_buff *skb,
57c67ff4 TH	220	struct udphdr *uh)
b582ef09 OG	221	{
	222	struct udp_offload_priv *uo_priv;
	223	struct sk_buff p, *pp = NULL;
57c67ff4 TH	224	struct udphdr *uh2;
57c67ff4 TH	225	unsigned int off = skb_gro_offset(skb);
b582ef09 OG	226	int flush = 1;
	227
	228	if (NAPI_GRO_CB(skb)->udp_mark \|\|
662880f4 TH	229	(skb->ip_summed != CHECKSUM_PARTIAL &&
	230	NAPI_GRO_CB(skb)->csum_cnt == 0 &&
	231	!NAPI_GRO_CB(skb)->csum_valid))
b582ef09 OG	232	goto out;
	233
	234	/* mark that this skb passed once through the udp gro layer */
	235	NAPI_GRO_CB(skb)->udp_mark = 1;
b582ef09 OG	236
	237	rcu_read_lock();
	238	uo_priv = rcu_dereference(udp_offload_base);
	239	for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
	240	if (uo_priv->offload->port == uh->dest &&
	241	uo_priv->offload->callbacks.gro_receive)
	242	goto unflush;
	243	}
	244	goto out_unlock;
	245
	246	unflush:
	247	flush = 0;
	248
	249	for (p = *head; p; p = p->next) {
	250	if (!NAPI_GRO_CB(p)->same_flow)
	251	continue;
	252
	253	uh2 = (struct udphdr *)(p->data + off);
57c67ff4 TH	254
	255	/* Match ports and either checksums are either both zero
	256	* or nonzero.
	257	*/
	258	if (((u32 )&uh->source != (u32 )&uh2->source) \|\|
	259	(!uh->check ^ !uh2->check)) {
b582ef09 OG	260	NAPI_GRO_CB(p)->same_flow = 0;
	261	continue;
	262	}
	263	}
	264
	265	skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
6bae1d4c	266	skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
afe93325	267	NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
b582ef09 OG	268	pp = uo_priv->offload->callbacks.gro_receive(head, skb);
	269
	270	out_unlock:
	271	rcu_read_unlock();
	272	out:
	273	NAPI_GRO_CB(skb)->flush \|= flush;
	274	return pp;
	275	}
	276
57c67ff4 TH	277	static struct sk_buff udp4_gro_receive(struct sk_buff head,
	278	struct sk_buff *skb)
	279	{
	280	struct udphdr *uh = udp_gro_udphdr(skb);
	281
2abb7cdc TH	282	if (unlikely(!uh))
2abb7cdc TH	283	goto flush;
57c67ff4	284
2abb7cdc	285	/* Don't bother verifying checksum if we're going to flush anyway. */
2d8f7e2c	286	if (NAPI_GRO_CB(skb)->flush)
2abb7cdc TH	287	goto skip;
	288
	289	if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
	290	inet_gro_compute_pseudo))
	291	goto flush;
	292	else if (uh->check)
	293	skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
	294	inet_gro_compute_pseudo);
	295	skip:
57c67ff4	296	return udp_gro_receive(head, skb, uh);
2abb7cdc TH	297
	298	flush:
	299	NAPI_GRO_CB(skb)->flush = 1;
	300	return NULL;
57c67ff4 TH	301	}
	302
	303	int udp_gro_complete(struct sk_buff *skb, int nhoff)
b582ef09 OG	304	{
	305	struct udp_offload_priv *uo_priv;
	306	__be16 newlen = htons(skb->len - nhoff);
	307	struct udphdr uh = (struct udphdr )(skb->data + nhoff);
	308	int err = -ENOSYS;
	309
	310	uh->len = newlen;
	311
	312	rcu_read_lock();
	313
	314	uo_priv = rcu_dereference(udp_offload_base);
	315	for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
	316	if (uo_priv->offload->port == uh->dest &&
	317	uo_priv->offload->callbacks.gro_complete)
	318	break;
	319	}
	320
afe93325 TH	321	if (uo_priv != NULL) {
afe93325 TH	322	NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
b582ef09	323	err = uo_priv->offload->callbacks.gro_complete(skb, nhoff + sizeof(struct udphdr));
afe93325	324	}
b582ef09 OG	325
	326	rcu_read_unlock();
	327	return err;
	328	}
	329
72bb17b3	330	static int udp4_gro_complete(struct sk_buff *skb, int nhoff)
57c67ff4 TH	331	{
	332	const struct iphdr *iph = ip_hdr(skb);
	333	struct udphdr uh = (struct udphdr )(skb->data + nhoff);
	334
	335	if (uh->check)
	336	uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
	337	iph->daddr, 0);
	338
	339	return udp_gro_complete(skb, nhoff);
	340	}
	341
da5bab07 DB	342	static const struct net_offload udpv4_offload = {
da5bab07 DB	343	.callbacks = {
da5bab07	344	.gso_segment = udp4_ufo_fragment,
57c67ff4 TH	345	.gro_receive = udp4_gro_receive,
57c67ff4 TH	346	.gro_complete = udp4_gro_complete,
da5bab07 DB	347	},
	348	};
	349
	350	int __init udpv4_offload_init(void)
	351	{
	352	return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
	353	}