sfe_ipv6_udp.c - codeaurora/qca-nss-sfe - Gitiles

 /*
  * sfe_ipv6_udp.c
  *	Shortcut forwarding engine file for IPv6 UDP
  *
  * Copyright (c) 2015-2016, 2019-2020, The Linux Foundation. All rights reserved.
  * Copyright (c) 2021 Qualcomm Innovation Center, Inc. All rights reserved.
  *
  * Permission to use, copy, modify, and/or distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
  * copyright notice and this permission notice appear in all copies.
  *
  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */

 #include <linux/skbuff.h>
 #include <net/udp.h>
 #include <linux/etherdevice.h>
 #include <linux/version.h>

 #include "sfe_debug.h"
 #include "sfe_api.h"
 #include "sfe.h"
 #include "sfe_flow_cookie.h"
 #include "sfe_ipv6.h"

 /*
  * sfe_ipv6_recv_udp()
  *	Handle UDP packet receives and forwarding.
  */
 int sfe_ipv6_recv_udp(struct sfe_ipv6 *si, struct sk_buff *skb, struct net_device *dev,
 			     unsigned int len, struct ipv6hdr *iph, unsigned int ihl, bool flush_on_find)
 {
 	struct udphdr *udph;
 	struct sfe_ipv6_addr *src_ip;
 	struct sfe_ipv6_addr *dest_ip;
 	__be16 src_port;
 	__be16 dest_port;
 	struct sfe_ipv6_connection_match *cm;
 	struct net_device *xmit_dev;
 	bool ret;
 	bool hw_csum;

 	/*
 	 * Is our packet too short to contain a valid UDP header?
 	 */
 	if (!pskb_may_pull(skb, (sizeof(struct udphdr) + ihl))) {

 		sfe_ipv6_exception_stats_inc(si,SFE_IPV6_EXCEPTION_EVENT_UDP_HEADER_INCOMPLETE);
 		DEBUG_TRACE("packet too short for UDP header\n");
 		return 0;
 	}

 	/*
 	 * Read the IP address and port information.  Read the IP header data first
 	 * because we've almost certainly got that in the cache.  We may not yet have
 	 * the UDP header cached though so allow more time for any prefetching.
 	 */
 	src_ip = (struct sfe_ipv6_addr *)iph->saddr.s6_addr32;
 	dest_ip = (struct sfe_ipv6_addr *)iph->daddr.s6_addr32;

 	udph = (struct udphdr *)(skb->data + ihl);
 	src_port = udph->source;
 	dest_port = udph->dest;

 	rcu_read_lock();

 	/*
 	 * Look for a connection match.
 	 */
 #ifdef CONFIG_NF_FLOW_COOKIE
 	cm = si->sfe_flow_cookie_table[skb->flow_cookie & SFE_FLOW_COOKIE_MASK].match;
 	if (unlikely(!cm)) {
 		cm = sfe_ipv6_find_connection_match_rcu(si, dev, IPPROTO_UDP, src_ip, src_port, dest_ip, dest_port);
 	}
 #else
 	cm = sfe_ipv6_find_connection_match_rcu(si, dev, IPPROTO_UDP, src_ip, src_port, dest_ip, dest_port);
 #endif
 	if (unlikely(!cm)) {
 		rcu_read_unlock();
 		sfe_ipv6_exception_stats_inc(si, SFE_IPV6_EXCEPTION_EVENT_UDP_NO_CONNECTION);

 		DEBUG_TRACE("no connection found\n");
 		return 0;
 	}

 	/*
 	 * If our packet has beern marked as "flush on find" we can't actually
 	 * forward it in the fast path, but now that we've found an associated
 	 * connection we can flush that out before we process the packet.
 	 */
 	if (unlikely(flush_on_find)) {
 		struct sfe_ipv6_connection *c = cm->connection;
 		spin_lock_bh(&si->lock);
 		ret = sfe_ipv6_remove_connection(si, c);
 		spin_unlock_bh(&si->lock);

 		DEBUG_TRACE("flush on find\n");
 		if (ret) {
 			sfe_ipv6_flush_connection(si, c, SFE_SYNC_REASON_FLUSH);
 		}
 		rcu_read_unlock();

 		sfe_ipv6_exception_stats_inc(si, SFE_IPV6_EXCEPTION_EVENT_UDP_IP_OPTIONS_OR_INITIAL_FRAGMENT);
 		return 0;
 	}

 #ifdef CONFIG_XFRM
 	/*
 	 * We can't accelerate the flow on this direction, just let it go
 	 * through the slow path.
 	 */
 	if (unlikely(!cm->flow_accel)) {
 		rcu_read_unlock();
 		this_cpu_inc(si->stats_pcpu->packets_not_forwarded64);
 		return 0;
 	}
 #endif

 	/*
 	 * Does our hop_limit allow forwarding?
 	 */
 	if (unlikely(iph->hop_limit < 2)) {
 		struct sfe_ipv6_connection *c = cm->connection;
 		spin_lock_bh(&si->lock);
 		ret = sfe_ipv6_remove_connection(si, c);
 		spin_unlock_bh(&si->lock);

 		DEBUG_TRACE("hop_limit too low\n");
 		if (ret) {
 			sfe_ipv6_flush_connection(si, c, SFE_SYNC_REASON_FLUSH);
 		}
 		rcu_read_unlock();

 		sfe_ipv6_exception_stats_inc(si, SFE_IPV6_EXCEPTION_EVENT_UDP_SMALL_TTL);
 		return 0;
 	}

 	/*
 	 * If our packet is larger than the MTU of the transmit interface then
 	 * we can't forward it easily.
 	 */
 	if (unlikely(len > cm->xmit_dev_mtu)) {
 		struct sfe_ipv6_connection *c = cm->connection;
 		spin_lock_bh(&si->lock);
 		ret = sfe_ipv6_remove_connection(si, c);
 		spin_unlock_bh(&si->lock);

 		DEBUG_TRACE("larger than mtu\n");
 		if (ret) {
 			sfe_ipv6_flush_connection(si, c, SFE_SYNC_REASON_FLUSH);
 		}
 		rcu_read_unlock();

 		sfe_ipv6_exception_stats_inc(si, SFE_IPV6_EXCEPTION_EVENT_UDP_NEEDS_FRAGMENTATION);
 		return 0;
 	}

 	/*
 	 * From this point on we're good to modify the packet.
 	 */

 	/*
 	 * Check if skb was cloned. If it was, unshare it. Because
 	 * the data area is going to be written in this path and we don't want to
 	 * change the cloned skb's data section.
 	 */
 	if (unlikely(skb_cloned(skb))) {
 		DEBUG_TRACE("%px: skb is a cloned skb\n", skb);
 		skb = skb_unshare(skb, GFP_ATOMIC);
                 if (!skb) {
 			DEBUG_WARN("Failed to unshare the cloned skb\n");
 			rcu_read_unlock();
 			return 0;
 		}

 		/*
 		 * Update the iph and udph pointers with the unshared skb's data area.
 		 */
 		iph = (struct ipv6hdr *)skb->data;
 		udph = (struct udphdr *)(skb->data + ihl);
 	}

 	/*
 	 * Update DSCP
 	 */
 	if (unlikely(cm->flags & SFE_IPV6_CONNECTION_MATCH_FLAG_DSCP_REMARK)) {
 		sfe_ipv6_change_dsfield(iph, cm->dscp);
 	}

 	/*
 	 * Decrement our hop_limit.
 	 */
 	iph->hop_limit -= 1;

 	/*
 	 * Enable HW csum if rx checksum is verified and xmit interface is CSUM offload capable.
 	 * Note: If L4 csum at Rx was found to be incorrect, we (router) should use incremental L4 checksum here
 	 * so that HW does not re-calculate/replace the L4 csum
 	 */
 	hw_csum = !!(cm->flags & SFE_IPV6_CONNECTION_MATCH_FLAG_CSUM_OFFLOAD) && (skb->ip_summed == CHECKSUM_UNNECESSARY);

 	/*
 	 * Do we have to perform translations of the source address/port?
 	 */
 	if (unlikely(cm->flags & SFE_IPV6_CONNECTION_MATCH_FLAG_XLATE_SRC)) {
 		u16 udp_csum;

 		iph->saddr.s6_addr32[0] = cm->xlate_src_ip[0].addr[0];
 		iph->saddr.s6_addr32[1] = cm->xlate_src_ip[0].addr[1];
 		iph->saddr.s6_addr32[2] = cm->xlate_src_ip[0].addr[2];
 		iph->saddr.s6_addr32[3] = cm->xlate_src_ip[0].addr[3];
 		udph->source = cm->xlate_src_port;

 		/*
 		 * Do we have a non-zero UDP checksum?  If we do then we need
 		 * to update it.
 		 */
 		if (unlikely(!hw_csum)) {
 			udp_csum = udph->check;
 			if (likely(udp_csum)) {
 				u32 sum = udp_csum + cm->xlate_src_csum_adjustment;
 				sum = (sum & 0xffff) + (sum >> 16);
 				udph->check = (u16)sum;
 			}
 		}
 	}

 	/*
 	 * Do we have to perform translations of the destination address/port?
 	 */
 	if (unlikely(cm->flags & SFE_IPV6_CONNECTION_MATCH_FLAG_XLATE_DEST)) {
 		u16 udp_csum;

 		iph->daddr.s6_addr32[0] = cm->xlate_dest_ip[0].addr[0];
 		iph->daddr.s6_addr32[1] = cm->xlate_dest_ip[0].addr[1];
 		iph->daddr.s6_addr32[2] = cm->xlate_dest_ip[0].addr[2];
 		iph->daddr.s6_addr32[3] = cm->xlate_dest_ip[0].addr[3];
 		udph->dest = cm->xlate_dest_port;

 		/*
 		 * Do we have a non-zero UDP checksum?  If we do then we need
 		 * to update it.
 		 */
 		if (unlikely(!hw_csum)) {
 			udp_csum = udph->check;
 			if (likely(udp_csum)) {
 				u32 sum = udp_csum + cm->xlate_dest_csum_adjustment;
 				sum = (sum & 0xffff) + (sum >> 16);
 				udph->check = (u16)sum;
 			}
 		}
 	}

 	/*
 	 * If HW checksum offload is not possible, incremental L4 checksum is used to update the packet.
 	 * Setting ip_summed to CHECKSUM_UNNECESSARY ensures checksum is not recalculated further in packet
 	 * path.
 	 */
 	if (likely(hw_csum)) {
 		skb->ip_summed = CHECKSUM_PARTIAL;
 	} else {
 		skb->ip_summed = CHECKSUM_UNNECESSARY;
 	}

 	/*
 	 * Update traffic stats.
 	 */
 	atomic_inc(&cm->rx_packet_count);
 	atomic_add(len, &cm->rx_byte_count);

 	xmit_dev = cm->xmit_dev;
 	skb->dev = xmit_dev;

 	/*
 	 * Check to see if we need to write a header.
 	 */
 	if (likely(cm->flags & SFE_IPV6_CONNECTION_MATCH_FLAG_WRITE_L2_HDR)) {
 		if (unlikely(!(cm->flags & SFE_IPV6_CONNECTION_MATCH_FLAG_WRITE_FAST_ETH_HDR))) {
 			dev_hard_header(skb, xmit_dev, ETH_P_IPV6,
 					cm->xmit_dest_mac, cm->xmit_src_mac, len);
 		} else {
 			/*
 			 * For the simple case we write this really fast.
 			 */
 			struct ethhdr *eth = (struct ethhdr *)__skb_push(skb, ETH_HLEN);
 			eth->h_proto = htons(ETH_P_IPV6);
 			ether_addr_copy((u8 *)eth->h_dest, (u8 *)cm->xmit_dest_mac);
 			ether_addr_copy((u8 *)eth->h_source, (u8 *)cm->xmit_src_mac);

 		}
 	}

 	/*
 	 * Update priority of skb.
 	 */
 	if (unlikely(cm->flags & SFE_IPV6_CONNECTION_MATCH_FLAG_PRIORITY_REMARK)) {
 		skb->priority = cm->priority;
 	}

 	/*
 	 * Mark outgoing packet.
 	 */
 	skb->mark = cm->connection->mark;
 	if (skb->mark) {
 		DEBUG_TRACE("SKB MARK is NON ZERO %x\n", skb->mark);
 	}

 	rcu_read_unlock();

 	this_cpu_inc(si->stats_pcpu->packets_forwarded64);

 	/*
 	 * We're going to check for GSO flags when we transmit the packet so
 	 * start fetching the necessary cache line now.
 	 */
 	prefetch(skb_shinfo(skb));

 	/*
 	 * Mark that this packet has been fast forwarded.
 	 */
 	skb->fast_forwarded = 1;

 	/*
 	 * Send the packet on its way.
 	 */
 	dev_queue_xmit(skb);

 	return 1;
 }
	/*
	* sfe_ipv6_udp.c
	* Shortcut forwarding engine file for IPv6 UDP
	*
	* Copyright (c) 2015-2016, 2019-2020, The Linux Foundation. All rights reserved.
	* Copyright (c) 2021 Qualcomm Innovation Center, Inc. All rights reserved.
	*
	* Permission to use, copy, modify, and/or distribute this software for any
	* purpose with or without fee is hereby granted, provided that the above
	* copyright notice and this permission notice appear in all copies.
	*
	* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
	* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
	* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
	* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
	* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
	* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
	* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
	*/

	#include <linux/skbuff.h>
	#include <net/udp.h>
	#include <linux/etherdevice.h>
	#include <linux/version.h>

	#include "sfe_debug.h"
	#include "sfe_api.h"
	#include "sfe.h"
	#include "sfe_flow_cookie.h"
	#include "sfe_ipv6.h"

	/*
	* sfe_ipv6_recv_udp()
	* Handle UDP packet receives and forwarding.
	*/
	int sfe_ipv6_recv_udp(struct sfe_ipv6 si, struct sk_buff skb, struct net_device *dev,
	unsigned int len, struct ipv6hdr *iph, unsigned int ihl, bool flush_on_find)
	{
	struct udphdr *udph;
	struct sfe_ipv6_addr *src_ip;
	struct sfe_ipv6_addr *dest_ip;
	__be16 src_port;
	__be16 dest_port;
	struct sfe_ipv6_connection_match *cm;
	struct net_device *xmit_dev;
	bool ret;
	bool hw_csum;

	/*
	* Is our packet too short to contain a valid UDP header?
	*/
	if (!pskb_may_pull(skb, (sizeof(struct udphdr) + ihl))) {

	sfe_ipv6_exception_stats_inc(si,SFE_IPV6_EXCEPTION_EVENT_UDP_HEADER_INCOMPLETE);
	DEBUG_TRACE("packet too short for UDP header\n");
	return 0;
	}

	/*
	* Read the IP address and port information. Read the IP header data first
	* because we've almost certainly got that in the cache. We may not yet have
	* the UDP header cached though so allow more time for any prefetching.
	*/
	src_ip = (struct sfe_ipv6_addr *)iph->saddr.s6_addr32;
	dest_ip = (struct sfe_ipv6_addr *)iph->daddr.s6_addr32;

	udph = (struct udphdr *)(skb->data + ihl);
	src_port = udph->source;
	dest_port = udph->dest;

	rcu_read_lock();

	/*
	* Look for a connection match.
	*/
	#ifdef CONFIG_NF_FLOW_COOKIE
	cm = si->sfe_flow_cookie_table[skb->flow_cookie & SFE_FLOW_COOKIE_MASK].match;
	if (unlikely(!cm)) {
	cm = sfe_ipv6_find_connection_match_rcu(si, dev, IPPROTO_UDP, src_ip, src_port, dest_ip, dest_port);
	}
	#else
	cm = sfe_ipv6_find_connection_match_rcu(si, dev, IPPROTO_UDP, src_ip, src_port, dest_ip, dest_port);
	#endif
	if (unlikely(!cm)) {
	rcu_read_unlock();
	sfe_ipv6_exception_stats_inc(si, SFE_IPV6_EXCEPTION_EVENT_UDP_NO_CONNECTION);

	DEBUG_TRACE("no connection found\n");
	return 0;
	}

	/*
	* If our packet has beern marked as "flush on find" we can't actually
	* forward it in the fast path, but now that we've found an associated
	* connection we can flush that out before we process the packet.
	*/
	if (unlikely(flush_on_find)) {
	struct sfe_ipv6_connection *c = cm->connection;
	spin_lock_bh(&si->lock);
	ret = sfe_ipv6_remove_connection(si, c);
	spin_unlock_bh(&si->lock);

	DEBUG_TRACE("flush on find\n");
	if (ret) {
	sfe_ipv6_flush_connection(si, c, SFE_SYNC_REASON_FLUSH);
	}
	rcu_read_unlock();

	sfe_ipv6_exception_stats_inc(si, SFE_IPV6_EXCEPTION_EVENT_UDP_IP_OPTIONS_OR_INITIAL_FRAGMENT);
	return 0;
	}

	#ifdef CONFIG_XFRM
	/*
	* We can't accelerate the flow on this direction, just let it go
	* through the slow path.
	*/
	if (unlikely(!cm->flow_accel)) {
	rcu_read_unlock();
	this_cpu_inc(si->stats_pcpu->packets_not_forwarded64);
	return 0;
	}
	#endif

	/*
	* Does our hop_limit allow forwarding?
	*/
	if (unlikely(iph->hop_limit < 2)) {
	struct sfe_ipv6_connection *c = cm->connection;
	spin_lock_bh(&si->lock);
	ret = sfe_ipv6_remove_connection(si, c);
	spin_unlock_bh(&si->lock);

	DEBUG_TRACE("hop_limit too low\n");
	if (ret) {
	sfe_ipv6_flush_connection(si, c, SFE_SYNC_REASON_FLUSH);
	}
	rcu_read_unlock();

	sfe_ipv6_exception_stats_inc(si, SFE_IPV6_EXCEPTION_EVENT_UDP_SMALL_TTL);
	return 0;
	}

	/*
	* If our packet is larger than the MTU of the transmit interface then
	* we can't forward it easily.
	*/
	if (unlikely(len > cm->xmit_dev_mtu)) {
	struct sfe_ipv6_connection *c = cm->connection;
	spin_lock_bh(&si->lock);
	ret = sfe_ipv6_remove_connection(si, c);
	spin_unlock_bh(&si->lock);

	DEBUG_TRACE("larger than mtu\n");
	if (ret) {
	sfe_ipv6_flush_connection(si, c, SFE_SYNC_REASON_FLUSH);
	}
	rcu_read_unlock();

	sfe_ipv6_exception_stats_inc(si, SFE_IPV6_EXCEPTION_EVENT_UDP_NEEDS_FRAGMENTATION);
	return 0;
	}

	/*
	* From this point on we're good to modify the packet.
	*/

	/*
	* Check if skb was cloned. If it was, unshare it. Because
	* the data area is going to be written in this path and we don't want to
	* change the cloned skb's data section.
	*/
	if (unlikely(skb_cloned(skb))) {
	DEBUG_TRACE("%px: skb is a cloned skb\n", skb);
	skb = skb_unshare(skb, GFP_ATOMIC);
	if (!skb) {
	DEBUG_WARN("Failed to unshare the cloned skb\n");
	rcu_read_unlock();
	return 0;
	}

	/*
	* Update the iph and udph pointers with the unshared skb's data area.
	*/
	iph = (struct ipv6hdr *)skb->data;
	udph = (struct udphdr *)(skb->data + ihl);
	}

	/*
	* Update DSCP
	*/
	if (unlikely(cm->flags & SFE_IPV6_CONNECTION_MATCH_FLAG_DSCP_REMARK)) {
	sfe_ipv6_change_dsfield(iph, cm->dscp);
	}

	/*
	* Decrement our hop_limit.
	*/
	iph->hop_limit -= 1;

	/*
	* Enable HW csum if rx checksum is verified and xmit interface is CSUM offload capable.
	* Note: If L4 csum at Rx was found to be incorrect, we (router) should use incremental L4 checksum here
	* so that HW does not re-calculate/replace the L4 csum
	*/
	hw_csum = !!(cm->flags & SFE_IPV6_CONNECTION_MATCH_FLAG_CSUM_OFFLOAD) && (skb->ip_summed == CHECKSUM_UNNECESSARY);

	/*
	* Do we have to perform translations of the source address/port?
	*/
	if (unlikely(cm->flags & SFE_IPV6_CONNECTION_MATCH_FLAG_XLATE_SRC)) {
	u16 udp_csum;

	iph->saddr.s6_addr32[0] = cm->xlate_src_ip[0].addr[0];
	iph->saddr.s6_addr32[1] = cm->xlate_src_ip[0].addr[1];
	iph->saddr.s6_addr32[2] = cm->xlate_src_ip[0].addr[2];
	iph->saddr.s6_addr32[3] = cm->xlate_src_ip[0].addr[3];
	udph->source = cm->xlate_src_port;

	/*
	* Do we have a non-zero UDP checksum? If we do then we need
	* to update it.
	*/
	if (unlikely(!hw_csum)) {
	udp_csum = udph->check;
	if (likely(udp_csum)) {
	u32 sum = udp_csum + cm->xlate_src_csum_adjustment;
	sum = (sum & 0xffff) + (sum >> 16);
	udph->check = (u16)sum;
	}
	}
	}

	/*
	* Do we have to perform translations of the destination address/port?
	*/
	if (unlikely(cm->flags & SFE_IPV6_CONNECTION_MATCH_FLAG_XLATE_DEST)) {
	u16 udp_csum;

	iph->daddr.s6_addr32[0] = cm->xlate_dest_ip[0].addr[0];
	iph->daddr.s6_addr32[1] = cm->xlate_dest_ip[0].addr[1];
	iph->daddr.s6_addr32[2] = cm->xlate_dest_ip[0].addr[2];
	iph->daddr.s6_addr32[3] = cm->xlate_dest_ip[0].addr[3];
	udph->dest = cm->xlate_dest_port;

	/*
	* Do we have a non-zero UDP checksum? If we do then we need
	* to update it.
	*/
	if (unlikely(!hw_csum)) {
	udp_csum = udph->check;
	if (likely(udp_csum)) {
	u32 sum = udp_csum + cm->xlate_dest_csum_adjustment;
	sum = (sum & 0xffff) + (sum >> 16);
	udph->check = (u16)sum;
	}
	}
	}

	/*
	* If HW checksum offload is not possible, incremental L4 checksum is used to update the packet.
	* Setting ip_summed to CHECKSUM_UNNECESSARY ensures checksum is not recalculated further in packet
	* path.
	*/
	if (likely(hw_csum)) {
	skb->ip_summed = CHECKSUM_PARTIAL;
	} else {
	skb->ip_summed = CHECKSUM_UNNECESSARY;
	}

	/*
	* Update traffic stats.
	*/
	atomic_inc(&cm->rx_packet_count);
	atomic_add(len, &cm->rx_byte_count);

	xmit_dev = cm->xmit_dev;
	skb->dev = xmit_dev;

	/*
	* Check to see if we need to write a header.
	*/
	if (likely(cm->flags & SFE_IPV6_CONNECTION_MATCH_FLAG_WRITE_L2_HDR)) {
	if (unlikely(!(cm->flags & SFE_IPV6_CONNECTION_MATCH_FLAG_WRITE_FAST_ETH_HDR))) {
	dev_hard_header(skb, xmit_dev, ETH_P_IPV6,
	cm->xmit_dest_mac, cm->xmit_src_mac, len);
	} else {
	/*
	* For the simple case we write this really fast.
	*/
	struct ethhdr eth = (struct ethhdr )__skb_push(skb, ETH_HLEN);
	eth->h_proto = htons(ETH_P_IPV6);
	ether_addr_copy((u8 )eth->h_dest, (u8 )cm->xmit_dest_mac);
	ether_addr_copy((u8 )eth->h_source, (u8 )cm->xmit_src_mac);

	}
	}

	/*
	* Update priority of skb.
	*/
	if (unlikely(cm->flags & SFE_IPV6_CONNECTION_MATCH_FLAG_PRIORITY_REMARK)) {
	skb->priority = cm->priority;
	}

	/*
	* Mark outgoing packet.
	*/
	skb->mark = cm->connection->mark;
	if (skb->mark) {
	DEBUG_TRACE("SKB MARK is NON ZERO %x\n", skb->mark);
	}

	rcu_read_unlock();

	this_cpu_inc(si->stats_pcpu->packets_forwarded64);

	/*
	* We're going to check for GSO flags when we transmit the packet so
	* start fetching the necessary cache line now.
	*/
	prefetch(skb_shinfo(skb));

	/*
	* Mark that this packet has been fast forwarded.
	*/
	skb->fast_forwarded = 1;

	/*
	* Send the packet on its way.
	*/
	dev_queue_xmit(skb);

	return 1;
	}