net/ipv4/gre_offload.c - arm/linux-arm-legacy - Git at Google

 /*
  *	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.
  *
  *	GRE GSO support
  */

 #include <linux/skbuff.h>
 #include <linux/init.h>
 #include <net/protocol.h>
 #include <net/gre.h>

 static int gre_gso_send_check(struct sk_buff *skb)
 {
 	if (!skb->encapsulation)
 		return -EINVAL;
 	return 0;
 }

 static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
 				       netdev_features_t features)
 {
 	struct sk_buff *segs = ERR_PTR(-EINVAL);
 	netdev_features_t enc_features;
 	int ghl;
 	struct gre_base_hdr *greh;
 	u16 mac_offset = skb->mac_header;
 	int mac_len = skb->mac_len;
 	__be16 protocol = skb->protocol;
 	int tnl_hlen;
 	bool csum;

 	if (unlikely(skb_shinfo(skb)->gso_type &
 				~(SKB_GSO_TCPV4 |
 				  SKB_GSO_TCPV6 |
 				  SKB_GSO_UDP |
 				  SKB_GSO_DODGY |
 				  SKB_GSO_TCP_ECN |
 				  SKB_GSO_GRE |
 				  SKB_GSO_IPIP)))
 		goto out;

 	if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
 		goto out;

 	greh = (struct gre_base_hdr *)skb_transport_header(skb);

 	ghl = skb_inner_network_header(skb) - skb_transport_header(skb);
 	if (unlikely(ghl < sizeof(*greh)))
 		goto out;

 	csum = !!(greh->flags & GRE_CSUM);

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

 	/* setup inner skb. */
 	skb->protocol = greh->protocol;
 	skb->encapsulation = 0;

 	__skb_pull(skb, ghl);
 	skb_reset_mac_header(skb);
 	skb_set_network_header(skb, skb_inner_network_offset(skb));
 	skb->mac_len = skb_inner_network_offset(skb);

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

 	skb = segs;
 	tnl_hlen = skb_tnl_header_len(skb);
 	do {
 		__skb_push(skb, ghl);
 		if (csum) {
 			__be32 *pcsum;

 			if (skb_has_shared_frag(skb)) {
 				int err;

 				err = __skb_linearize(skb);
 				if (err) {
 					kfree_skb_list(segs);
 					segs = ERR_PTR(err);
 					goto out;
 				}
 			}

 			greh = (struct gre_base_hdr *)(skb->data);
 			pcsum = (__be32 *)(greh + 1);
 			*pcsum = 0;
 			*(__sum16 *)pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0));
 		}
 		__skb_push(skb, tnl_hlen - ghl);

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

 		skb_reset_mac_header(skb);
 		skb_set_network_header(skb, mac_len);
 		skb->mac_len = mac_len;
 		skb->protocol = protocol;
 	} while ((skb = skb->next));
 out:
 	return segs;
 }

 /* Compute the whole skb csum in s/w and store it, then verify GRO csum
  * starting from gro_offset.
  */
 static __sum16 gro_skb_checksum(struct sk_buff *skb)
 {
 	__sum16 sum;

 	skb->csum = skb_checksum(skb, 0, skb->len, 0);
 	NAPI_GRO_CB(skb)->csum = csum_sub(skb->csum,
 		csum_partial(skb->data, skb_gro_offset(skb), 0));
 	sum = csum_fold(NAPI_GRO_CB(skb)->csum);
 	if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE)) {
 		if (unlikely(!sum))
 			netdev_rx_csum_fault(skb->dev);
 	} else
 		skb->ip_summed = CHECKSUM_COMPLETE;

 	return sum;
 }

 static struct sk_buff **gre_gro_receive(struct sk_buff **head,
 					struct sk_buff *skb)
 {
 	struct sk_buff **pp = NULL;
 	struct sk_buff *p;
 	const struct gre_base_hdr *greh;
 	unsigned int hlen, grehlen;
 	unsigned int off;
 	int flush = 1;
 	struct packet_offload *ptype;
 	__be16 type;

 	off = skb_gro_offset(skb);
 	hlen = off + sizeof(*greh);
 	greh = skb_gro_header_fast(skb, off);
 	if (skb_gro_header_hard(skb, hlen)) {
 		greh = skb_gro_header_slow(skb, hlen, off);
 		if (unlikely(!greh))
 			goto out;
 	}

 	/* Only support version 0 and K (key), C (csum) flags. Note that
 	 * although the support for the S (seq#) flag can be added easily
 	 * for GRO, this is problematic for GSO hence can not be enabled
 	 * here because a GRO pkt may end up in the forwarding path, thus
 	 * requiring GSO support to break it up correctly.
 	 */
 	if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
 		goto out;

 	type = greh->protocol;

 	rcu_read_lock();
 	ptype = gro_find_receive_by_type(type);
 	if (ptype == NULL)
 		goto out_unlock;

 	grehlen = GRE_HEADER_SECTION;

 	if (greh->flags & GRE_KEY)
 		grehlen += GRE_HEADER_SECTION;

 	if (greh->flags & GRE_CSUM)
 		grehlen += GRE_HEADER_SECTION;

 	hlen = off + grehlen;
 	if (skb_gro_header_hard(skb, hlen)) {
 		greh = skb_gro_header_slow(skb, hlen, off);
 		if (unlikely(!greh))
 			goto out_unlock;
 	}
 	if (greh->flags & GRE_CSUM) { /* Need to verify GRE csum first */
 		__sum16 csum = 0;

 		if (skb->ip_summed == CHECKSUM_COMPLETE)
 			csum = csum_fold(NAPI_GRO_CB(skb)->csum);
 		/* Don't trust csum error calculated/reported by h/w */
 		if (skb->ip_summed == CHECKSUM_NONE || csum != 0)
 			csum = gro_skb_checksum(skb);

 		/* GRE CSUM is the 1's complement of the 1's complement sum
 		 * of the GRE hdr plus payload so it should add up to 0xffff
 		 * (and 0 after csum_fold()) just like the IPv4 hdr csum.
 		 */
 		if (csum)
 			goto out_unlock;
 	}
 	flush = 0;

 	for (p = *head; p; p = p->next) {
 		const struct gre_base_hdr *greh2;

 		if (!NAPI_GRO_CB(p)->same_flow)
 			continue;

 		/* The following checks are needed to ensure only pkts
 		 * from the same tunnel are considered for aggregation.
 		 * The criteria for "the same tunnel" includes:
 		 * 1) same version (we only support version 0 here)
 		 * 2) same protocol (we only support ETH_P_IP for now)
 		 * 3) same set of flags
 		 * 4) same key if the key field is present.
 		 */
 		greh2 = (struct gre_base_hdr *)(p->data + off);

 		if (greh2->flags != greh->flags ||
 		    greh2->protocol != greh->protocol) {
 			NAPI_GRO_CB(p)->same_flow = 0;
 			continue;
 		}
 		if (greh->flags & GRE_KEY) {
 			/* compare keys */
 			if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
 				NAPI_GRO_CB(p)->same_flow = 0;
 				continue;
 			}
 		}
 	}

 	skb_gro_pull(skb, grehlen);

 	/* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
 	skb_gro_postpull_rcsum(skb, greh, grehlen);

 	pp = ptype->callbacks.gro_receive(head, skb);

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

 	return pp;
 }

 static int gre_gro_complete(struct sk_buff *skb, int nhoff)
 {
 	struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
 	struct packet_offload *ptype;
 	unsigned int grehlen = sizeof(*greh);
 	int err = -ENOENT;
 	__be16 type;

 	type = greh->protocol;
 	if (greh->flags & GRE_KEY)
 		grehlen += GRE_HEADER_SECTION;

 	if (greh->flags & GRE_CSUM)
 		grehlen += GRE_HEADER_SECTION;

 	rcu_read_lock();
 	ptype = gro_find_complete_by_type(type);
 	if (ptype != NULL)
 		err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);

 	rcu_read_unlock();
 	return err;
 }

 static const struct net_offload gre_offload = {
 	.callbacks = {
 		.gso_send_check = gre_gso_send_check,
 		.gso_segment = gre_gso_segment,
 		.gro_receive = gre_gro_receive,
 		.gro_complete = gre_gro_complete,
 	},
 };

 static int __init gre_offload_init(void)
 {
 	return inet_add_offload(&gre_offload, IPPROTO_GRE);
 }
 device_initcall(gre_offload_init);
	/*
	* 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.
	*
	* GRE GSO support
	*/

	#include <linux/skbuff.h>
	#include <linux/init.h>
	#include <net/protocol.h>
	#include <net/gre.h>

	static int gre_gso_send_check(struct sk_buff *skb)
	{
	if (!skb->encapsulation)
	return -EINVAL;
	return 0;
	}

	static struct sk_buff gre_gso_segment(struct sk_buff skb,
	netdev_features_t features)
	{
	struct sk_buff *segs = ERR_PTR(-EINVAL);
	netdev_features_t enc_features;
	int ghl;
	struct gre_base_hdr *greh;
	u16 mac_offset = skb->mac_header;
	int mac_len = skb->mac_len;
	__be16 protocol = skb->protocol;
	int tnl_hlen;
	bool csum;

	if (unlikely(skb_shinfo(skb)->gso_type &
	~(SKB_GSO_TCPV4 \|
	SKB_GSO_TCPV6 \|
	SKB_GSO_UDP \|
	SKB_GSO_DODGY \|
	SKB_GSO_TCP_ECN \|
	SKB_GSO_GRE \|
	SKB_GSO_IPIP)))
	goto out;

	if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
	goto out;

	greh = (struct gre_base_hdr *)skb_transport_header(skb);

	ghl = skb_inner_network_header(skb) - skb_transport_header(skb);
	if (unlikely(ghl < sizeof(*greh)))
	goto out;

	csum = !!(greh->flags & GRE_CSUM);

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

	/* setup inner skb. */
	skb->protocol = greh->protocol;
	skb->encapsulation = 0;

	__skb_pull(skb, ghl);
	skb_reset_mac_header(skb);
	skb_set_network_header(skb, skb_inner_network_offset(skb));
	skb->mac_len = skb_inner_network_offset(skb);

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

	skb = segs;
	tnl_hlen = skb_tnl_header_len(skb);
	do {
	__skb_push(skb, ghl);
	if (csum) {
	__be32 *pcsum;

	if (skb_has_shared_frag(skb)) {
	int err;

	err = __skb_linearize(skb);
	if (err) {
	kfree_skb_list(segs);
	segs = ERR_PTR(err);
	goto out;
	}
	}

	greh = (struct gre_base_hdr *)(skb->data);
	pcsum = (__be32 *)(greh + 1);
	*pcsum = 0;
	(__sum16 )pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0));
	}
	__skb_push(skb, tnl_hlen - ghl);

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

	skb_reset_mac_header(skb);
	skb_set_network_header(skb, mac_len);
	skb->mac_len = mac_len;
	skb->protocol = protocol;
	} while ((skb = skb->next));
	out:
	return segs;
	}

	/* Compute the whole skb csum in s/w and store it, then verify GRO csum
	* starting from gro_offset.
	*/
	static __sum16 gro_skb_checksum(struct sk_buff *skb)
	{
	__sum16 sum;

	skb->csum = skb_checksum(skb, 0, skb->len, 0);
	NAPI_GRO_CB(skb)->csum = csum_sub(skb->csum,
	csum_partial(skb->data, skb_gro_offset(skb), 0));
	sum = csum_fold(NAPI_GRO_CB(skb)->csum);
	if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE)) {
	if (unlikely(!sum))
	netdev_rx_csum_fault(skb->dev);
	} else
	skb->ip_summed = CHECKSUM_COMPLETE;

	return sum;
	}

	static struct sk_buff gre_gro_receive(struct sk_buff head,
	struct sk_buff *skb)
	{
	struct sk_buff **pp = NULL;
	struct sk_buff *p;
	const struct gre_base_hdr *greh;
	unsigned int hlen, grehlen;
	unsigned int off;
	int flush = 1;
	struct packet_offload *ptype;
	__be16 type;

	off = skb_gro_offset(skb);
	hlen = off + sizeof(*greh);
	greh = skb_gro_header_fast(skb, off);
	if (skb_gro_header_hard(skb, hlen)) {
	greh = skb_gro_header_slow(skb, hlen, off);
	if (unlikely(!greh))
	goto out;
	}

	/* Only support version 0 and K (key), C (csum) flags. Note that
	* although the support for the S (seq#) flag can be added easily
	* for GRO, this is problematic for GSO hence can not be enabled
	* here because a GRO pkt may end up in the forwarding path, thus
	* requiring GSO support to break it up correctly.
	*/
	if ((greh->flags & ~(GRE_KEY\|GRE_CSUM)) != 0)
	goto out;

	type = greh->protocol;

	rcu_read_lock();
	ptype = gro_find_receive_by_type(type);
	if (ptype == NULL)
	goto out_unlock;

	grehlen = GRE_HEADER_SECTION;

	if (greh->flags & GRE_KEY)
	grehlen += GRE_HEADER_SECTION;

	if (greh->flags & GRE_CSUM)
	grehlen += GRE_HEADER_SECTION;

	hlen = off + grehlen;
	if (skb_gro_header_hard(skb, hlen)) {
	greh = skb_gro_header_slow(skb, hlen, off);
	if (unlikely(!greh))
	goto out_unlock;
	}
	if (greh->flags & GRE_CSUM) { /* Need to verify GRE csum first */
	__sum16 csum = 0;

	if (skb->ip_summed == CHECKSUM_COMPLETE)
	csum = csum_fold(NAPI_GRO_CB(skb)->csum);
	/* Don't trust csum error calculated/reported by h/w */
	if (skb->ip_summed == CHECKSUM_NONE \|\| csum != 0)
	csum = gro_skb_checksum(skb);

	/* GRE CSUM is the 1's complement of the 1's complement sum
	* of the GRE hdr plus payload so it should add up to 0xffff
	* (and 0 after csum_fold()) just like the IPv4 hdr csum.
	*/
	if (csum)
	goto out_unlock;
	}
	flush = 0;

	for (p = *head; p; p = p->next) {
	const struct gre_base_hdr *greh2;

	if (!NAPI_GRO_CB(p)->same_flow)
	continue;

	/* The following checks are needed to ensure only pkts
	* from the same tunnel are considered for aggregation.
	* The criteria for "the same tunnel" includes:
	* 1) same version (we only support version 0 here)
	* 2) same protocol (we only support ETH_P_IP for now)
	* 3) same set of flags
	* 4) same key if the key field is present.
	*/
	greh2 = (struct gre_base_hdr *)(p->data + off);

	if (greh2->flags != greh->flags \|\|
	greh2->protocol != greh->protocol) {
	NAPI_GRO_CB(p)->same_flow = 0;
	continue;
	}
	if (greh->flags & GRE_KEY) {
	/* compare keys */
	if ((__be32 )(greh2+1) != (__be32 )(greh+1)) {
	NAPI_GRO_CB(p)->same_flow = 0;
	continue;
	}
	}
	}

	skb_gro_pull(skb, grehlen);

	/* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
	skb_gro_postpull_rcsum(skb, greh, grehlen);

	pp = ptype->callbacks.gro_receive(head, skb);

	out_unlock:
	rcu_read_unlock();
	out:
	NAPI_GRO_CB(skb)->flush \|= flush;

	return pp;
	}

	static int gre_gro_complete(struct sk_buff *skb, int nhoff)
	{
	struct gre_base_hdr greh = (struct gre_base_hdr )(skb->data + nhoff);
	struct packet_offload *ptype;
	unsigned int grehlen = sizeof(*greh);
	int err = -ENOENT;
	__be16 type;

	type = greh->protocol;
	if (greh->flags & GRE_KEY)
	grehlen += GRE_HEADER_SECTION;

	if (greh->flags & GRE_CSUM)
	grehlen += GRE_HEADER_SECTION;

	rcu_read_lock();
	ptype = gro_find_complete_by_type(type);
	if (ptype != NULL)
	err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);

	rcu_read_unlock();
	return err;
	}

	static const struct net_offload gre_offload = {
	.callbacks = {
	.gso_send_check = gre_gso_send_check,
	.gso_segment = gre_gso_segment,
	.gro_receive = gre_gro_receive,
	.gro_complete = gre_gro_complete,
	},
	};

	static int __init gre_offload_init(void)
	{
	return inet_add_offload(&gre_offload, IPPROTO_GRE);
	}
	device_initcall(gre_offload_init);