sfe_ipv4_gre.c - codeaurora/qca-nss-sfe - Gitiles

 /*
  * sfe_ipv4_gre.c
  *	Shortcut forwarding engine file for IPv4 GRE
  *
  * Copyright (c) 2022 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/protocol.h>
 #include <linux/etherdevice.h>
 #include <linux/lockdep.h>
 #include <net/ip.h>
 #include <net/gre.h>
 #include <net/pptp.h>

 #include "sfe_debug.h"
 #include "sfe_api.h"
 #include "sfe.h"
 #include "sfe_flow_cookie.h"
 #include "sfe_ipv4.h"
 #include "sfe_pppoe.h"
 #include "sfe_vlan.h"

 /*
  * sfe_ipv4_recv_gre()
  *	GRE tunnel packet receive and forwarding.
  */
 int sfe_ipv4_recv_gre(struct sfe_ipv4 *si, struct sk_buff *skb, struct net_device *dev,
 		      unsigned int len, struct iphdr *iph, unsigned int ihl, bool sync_on_find,
 		      struct sfe_l2_info *l2_info, bool tun_outer)
 {
 	struct sfe_ipv4_connection_match *cm;
 	struct pptp_gre_header *pptp_hdr;
 	struct gre_base_hdr *gre_hdr;
 	struct net_device *xmit_dev;
 	__be16 dest_port = 0;
 	bool passthrough;
 	bool bridge_flow;
 	__be32 dest_ip;
 	__be32 src_ip;
 	bool hw_csum;
 	bool ret;
 	u8 ttl;

 	/*
 	 * Is our packet too short to contain a valid GRE header?
 	 */
 	if (unlikely(!pskb_may_pull(skb, sizeof(*gre_hdr) + ihl))) {
 		sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_GRE_HEADER_INCOMPLETE);
 		DEBUG_TRACE("packet too short for GRE header\n");
 		return 0;
 	}


 	/*
 	 * Read the source and destination IP address.
 	 */
 	src_ip = iph->saddr;
 	dest_ip = iph->daddr;

 	rcu_read_lock();

 	/*
 	 * Look for a connection match with 4 tuple if it is PPTP
 	 */
 	gre_hdr = (struct gre_base_hdr *)(skb->data + ihl);

 	if ((gre_hdr->protocol == GRE_PROTO_PPP) && likely(pskb_may_pull(skb, (sizeof(*pptp_hdr) - 8) + ihl))) {
 		pptp_hdr = (struct pptp_gre_header *)(skb->data + ihl);
 		dest_port = pptp_hdr->call_id;
 	}

 #ifdef CONFIG_NF_FLOW_COOKIE
 	cm = si->sfe_flow_cookie_table[skb->flow_cookie & SFE_FLOW_COOKIE_MASK].match;
 	if (unlikely(!cm)) {
 		cm = sfe_ipv4_find_connection_match_rcu(si, dev, IPPROTO_GRE, src_ip, 0, dest_ip, dest_port);
 	}
 #else
 	cm = sfe_ipv4_find_connection_match_rcu(si, dev, IPPROTO_GRE, src_ip, 0, dest_ip, dest_port);
 #endif

 	if (unlikely(!cm)) {
 		rcu_read_unlock();
 		sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_GRE_NO_CONNECTION);
 		DEBUG_INFO("no GRE connection match found dev %s src ip %pI4 dest ip %pI4 port %d\n", dev->name, &src_ip, &dest_ip, ntohs(dest_port));
 		return 0;
 	}

 	/*
 	 * Source interface validate.
 	 */
 	if (unlikely((cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_SRC_INTERFACE_CHECK) && (cm->match_dev != dev))) {
 		if (!(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_SRC_INTERFACE_CHECK_NO_FLUSH)) {
 			struct sfe_ipv4_connection *c = cm->connection;
 			int ret;

 			DEBUG_TRACE("flush on source interface check failure\n");
 			spin_lock_bh(&si->lock);
 			ret = sfe_ipv4_remove_connection(si, c);
 			spin_unlock_bh(&si->lock);

 			if (ret) {
 				sfe_ipv4_flush_connection(si, c, SFE_SYNC_REASON_FLUSH);
 			}
 		}
 		rcu_read_unlock();
 		sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_INVALID_SRC_IFACE);
 		DEBUG_TRACE("exception the packet on source interface check failure\n");
 		return 0;
 	}

 	passthrough = cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_PASSTHROUGH;

 	/*
 	 * If our packet has been marked as "sync on find" we can't actually
 	 * forward it in the fast path, but now that we've found an associated
 	 * connection we need sync its status before exception it to slow path unless
 	 * it is passthrough (packets not directed to DUT) packet.
 	 * TODO: revisit to ensure that pass through traffic is not bypassing firewall for fragmented cases
 	 */
 	if (unlikely(sync_on_find) && !passthrough) {
 		/*
 		 * if we put IP fragmented packets in slow path and non IP fragmented packet in fastpath,
 		 * this causes out of order pptp sequence number being received at pptp_rcv_core(). So we need to
 		 * flush the rule for the tunnel which has sequence number to avoid out of order sequence number.
 		 */
 		if ((gre_hdr->protocol == GRE_PROTO_PPP) && (ntohs(iph->frag_off) & IP_MF)) {
 			struct sfe_ipv4_connection *c = cm->connection;
 			int ret;

 			spin_lock_bh(&si->lock);
 			ret = sfe_ipv4_remove_connection(si, c);
 			spin_unlock_bh(&si->lock);

 			if (ret) {
 				sfe_ipv4_flush_connection(si, c, SFE_SYNC_REASON_FLUSH);
 			}

 			rcu_read_unlock();
 			sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_GRE_IP_OPTIONS_OR_INITIAL_FRAGMENT);
 			DEBUG_TRACE("%px: sfe: pptp cm flushed\n", cm);
 			return 0;
 		}

 		sfe_ipv4_sync_status(si, cm->connection, SFE_SYNC_REASON_STATS);
 		rcu_read_unlock();
 		sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_GRE_IP_OPTIONS_OR_INITIAL_FRAGMENT);
 		DEBUG_TRACE("%px: sfe: sync on find\n", cm);
 		return 0;
 	}

 	/*
 	 * Do we expect an ingress VLAN tag for this flow?
 	 */
 	if (unlikely(!sfe_vlan_validate_ingress_tag(skb, cm->ingress_vlan_hdr_cnt, cm->ingress_vlan_hdr, l2_info))) {
 		rcu_read_unlock();
 		sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_INGRESS_VLAN_TAG_MISMATCH);
 		DEBUG_TRACE("VLAN tag mismatch. skb=%px\n", skb);
 		return 0;
 	}

 	bridge_flow = !!(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_BRIDGE_FLOW);

 	/*
 	 * Does our TTL allow forwarding?
 	 */
 	ttl = iph->ttl;
 	if (!bridge_flow && (ttl < 2) && passthrough) {
 		sfe_ipv4_sync_status(si, cm->connection, SFE_SYNC_REASON_STATS);
 		rcu_read_unlock();

 		DEBUG_TRACE("%px: sfe: TTL too low\n", skb);
 		sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_GRE_SMALL_TTL);
 		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 1;
 		}

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

 	/*
 	 * For PPPoE packets, match server MAC and session id
 	 */
 	if (unlikely(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_PPPOE_DECAP)) {
 		struct ethhdr *eth;
 		bool pppoe_match;

 		if (unlikely(!sfe_l2_parse_flag_check(l2_info, SFE_L2_PARSE_FLAGS_PPPOE_INGRESS))) {
 			rcu_read_unlock();
 			DEBUG_TRACE("%px: PPPoE header not present in packet for PPPoE rule\n", skb);
 			sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_INCORRECT_PPPOE_PARSING);
 			return 0;
 		}

 		eth = eth_hdr(skb);

 		pppoe_match = (cm->pppoe_session_id == sfe_l2_pppoe_session_id_get(l2_info)) &&
 				ether_addr_equal((u8*)cm->pppoe_remote_mac, (u8 *)eth->h_source);

 		if (unlikely(!pppoe_match)) {
 			DEBUG_TRACE("%px: PPPoE session ID %d and %d or MAC %pM and %pM did not match\n",
 					skb, cm->pppoe_session_id, sfe_l2_pppoe_session_id_get(l2_info),
 					cm->pppoe_remote_mac, eth->h_source);
 			rcu_read_unlock();
 			sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_INVALID_PPPOE_SESSION);
 			return 0;
 		}

 		skb->protocol = htons(l2_info->protocol);
 		this_cpu_inc(si->stats_pcpu->pppoe_decap_packets_forwarded64);
 	} else if (unlikely(sfe_l2_parse_flag_check(l2_info, SFE_L2_PARSE_FLAGS_PPPOE_INGRESS))) {

 		/*
 		 * If packet contains PPPoE header but CME doesn't contain PPPoE flag yet we are exceptioning
 		 * the packet to linux
 		 */
 		if (unlikely(!(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_BRIDGE_FLOW))) {
 			rcu_read_unlock();
 			DEBUG_TRACE("%px: CME doesn't contain PPPoE flag but packet has PPPoE header\n", skb);
 			sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_PPPOE_NOT_SET_IN_CME);
 			return 0;

 		}

 		/*
 		 * For bridged flows when packet contains PPPoE header, restore the header back and forward
 		 * to xmit interface
 		 */
 		__skb_push(skb, (sizeof(struct pppoe_hdr) + sizeof(struct sfe_ppp_hdr)));

 		this_cpu_inc(si->stats_pcpu->pppoe_bridge_packets_forwarded64);
 	}

 	/*
 	 * protocol handler will be valid only in decap-path.
 	 */
 	if (cm->proto) {
 		struct net_protocol *ipprot = cm->proto;
 		skb_reset_network_header(skb);
 		skb_pull(skb, ihl);
 		skb_reset_transport_header(skb);
 		skb->fast_forwarded = 1;

 		ret = ipprot->handler(skb);
 		if (ret) {
 			this_cpu_inc(si->stats_pcpu->packets_not_forwarded64);
 			rcu_read_unlock();
 			DEBUG_TRACE("GRE handler returned error %u\n", ret);
 			return 1;
 		}

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

 		this_cpu_inc(si->stats_pcpu->packets_forwarded64);
 		rcu_read_unlock();
 		return 1;
 	}

 	/*
 	 * Check if skb has enough headroom to write L2 headers
 	 */
 	if (unlikely(skb_headroom(skb) < cm->l2_hdr_size)) {
 		rcu_read_unlock();
 		DEBUG_WARN("%px: Not enough headroom: %u\n", skb, skb_headroom(skb));
 		sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_NO_HEADROOM);
 		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)) {
 		sfe_ipv4_sync_status(si, cm->connection, SFE_SYNC_REASON_STATS);
 		rcu_read_unlock();
 		sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_GRE_NEEDS_FRAGMENTATION);
 		DEBUG_TRACE("%px: sfe: larger than MTU\n", cm);
 		return 0;
 	}

 	/*
 	 * Decrement our TTL
 	 */
 	iph->ttl = (ttl - (u8)(!bridge_flow && !tun_outer));

 	/*
 	 * Update DSCP
 	 */
 	if (unlikely(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_DSCP_REMARK)) {
 		iph->tos = (iph->tos & SFE_IPV4_DSCP_MASK) | cm->dscp;
 	}

 	/*
 	 * Enable HW csum if rx checksum is verified and xmit interface is CSUM offload capable.
 	 */
 	hw_csum = !!(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_CSUM_OFFLOAD) && (skb->ip_summed == CHECKSUM_UNNECESSARY);

 	/*
 	 * Replace the IP checksum.
 	 */
 	if (likely(hw_csum)) {
 		skb->ip_summed = CHECKSUM_PARTIAL;
 	} else {
 		iph->check = sfe_ipv4_gen_ip_csum(iph);
 	}

 	/*
 	 * 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;

 	/*
 	 * For PPPoE flows, add PPPoE header before L2 header is added.
 	 */
 	if (unlikely(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_PPPOE_ENCAP)) {
 		sfe_pppoe_add_header(skb, cm->pppoe_session_id, PPP_IP);
 		this_cpu_inc(si->stats_pcpu->pppoe_encap_packets_forwarded64);
 	}

 	/*
 	 * Check to see if we need to add VLAN tags
 	 */
 	if (unlikely(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_INSERT_EGRESS_VLAN_TAG)) {
 		sfe_vlan_add_tag(skb, cm->egress_vlan_hdr_cnt, cm->egress_vlan_hdr);
 	}

 	/*
 	 * For the simple case we write this really fast.
 	 */
 	if (cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_WRITE_FAST_ETH_HDR) {
 		struct ethhdr *eth = (struct ethhdr *)__skb_push(skb, ETH_HLEN);
 		eth->h_proto = skb->protocol;
 		ether_addr_copy((u8 *)eth->h_dest, (u8 *)cm->xmit_dest_mac);
 		ether_addr_copy((u8 *)eth->h_source, (u8 *)cm->xmit_src_mac);
 	} else if (cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_WRITE_L2_HDR) {
 		dev_hard_header(skb, xmit_dev, ntohs(skb->protocol), cm->xmit_dest_mac, cm->xmit_src_mac, len);
 	}

 	/*
 	 * Update priority of skb.
 	 */
 	if (unlikely(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_PRIORITY_REMARK)) {
 		skb->priority = cm->priority;
 	}

 	/*
 	 * Mark outgoing packet.
 	 */
 	if (unlikely(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_MARK)) {
 		skb->mark = cm->mark;
 	}

 	this_cpu_inc(si->stats_pcpu->packets_forwarded64);

 	rcu_read_unlock();

 	/*
 	 * 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_ipv4_gre.c
	* Shortcut forwarding engine file for IPv4 GRE
	*
	* Copyright (c) 2022 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/protocol.h>
	#include <linux/etherdevice.h>
	#include <linux/lockdep.h>
	#include <net/ip.h>
	#include <net/gre.h>
	#include <net/pptp.h>

	#include "sfe_debug.h"
	#include "sfe_api.h"
	#include "sfe.h"
	#include "sfe_flow_cookie.h"
	#include "sfe_ipv4.h"
	#include "sfe_pppoe.h"
	#include "sfe_vlan.h"

	/*
	* sfe_ipv4_recv_gre()
	* GRE tunnel packet receive and forwarding.
	*/
	int sfe_ipv4_recv_gre(struct sfe_ipv4 si, struct sk_buff skb, struct net_device *dev,
	unsigned int len, struct iphdr *iph, unsigned int ihl, bool sync_on_find,
	struct sfe_l2_info *l2_info, bool tun_outer)
	{
	struct sfe_ipv4_connection_match *cm;
	struct pptp_gre_header *pptp_hdr;
	struct gre_base_hdr *gre_hdr;
	struct net_device *xmit_dev;
	__be16 dest_port = 0;
	bool passthrough;
	bool bridge_flow;
	__be32 dest_ip;
	__be32 src_ip;
	bool hw_csum;
	bool ret;
	u8 ttl;

	/*
	* Is our packet too short to contain a valid GRE header?
	*/
	if (unlikely(!pskb_may_pull(skb, sizeof(*gre_hdr) + ihl))) {
	sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_GRE_HEADER_INCOMPLETE);
	DEBUG_TRACE("packet too short for GRE header\n");
	return 0;
	}


	/*
	* Read the source and destination IP address.
	*/
	src_ip = iph->saddr;
	dest_ip = iph->daddr;

	rcu_read_lock();

	/*
	* Look for a connection match with 4 tuple if it is PPTP
	*/
	gre_hdr = (struct gre_base_hdr *)(skb->data + ihl);

	if ((gre_hdr->protocol == GRE_PROTO_PPP) && likely(pskb_may_pull(skb, (sizeof(*pptp_hdr) - 8) + ihl))) {
	pptp_hdr = (struct pptp_gre_header *)(skb->data + ihl);
	dest_port = pptp_hdr->call_id;
	}

	#ifdef CONFIG_NF_FLOW_COOKIE
	cm = si->sfe_flow_cookie_table[skb->flow_cookie & SFE_FLOW_COOKIE_MASK].match;
	if (unlikely(!cm)) {
	cm = sfe_ipv4_find_connection_match_rcu(si, dev, IPPROTO_GRE, src_ip, 0, dest_ip, dest_port);
	}
	#else
	cm = sfe_ipv4_find_connection_match_rcu(si, dev, IPPROTO_GRE, src_ip, 0, dest_ip, dest_port);
	#endif

	if (unlikely(!cm)) {
	rcu_read_unlock();
	sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_GRE_NO_CONNECTION);
	DEBUG_INFO("no GRE connection match found dev %s src ip %pI4 dest ip %pI4 port %d\n", dev->name, &src_ip, &dest_ip, ntohs(dest_port));
	return 0;
	}

	/*
	* Source interface validate.
	*/
	if (unlikely((cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_SRC_INTERFACE_CHECK) && (cm->match_dev != dev))) {
	if (!(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_SRC_INTERFACE_CHECK_NO_FLUSH)) {
	struct sfe_ipv4_connection *c = cm->connection;
	int ret;

	DEBUG_TRACE("flush on source interface check failure\n");
	spin_lock_bh(&si->lock);
	ret = sfe_ipv4_remove_connection(si, c);
	spin_unlock_bh(&si->lock);

	if (ret) {
	sfe_ipv4_flush_connection(si, c, SFE_SYNC_REASON_FLUSH);
	}
	}
	rcu_read_unlock();
	sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_INVALID_SRC_IFACE);
	DEBUG_TRACE("exception the packet on source interface check failure\n");
	return 0;
	}

	passthrough = cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_PASSTHROUGH;

	/*
	* If our packet has been marked as "sync on find" we can't actually
	* forward it in the fast path, but now that we've found an associated
	* connection we need sync its status before exception it to slow path unless
	* it is passthrough (packets not directed to DUT) packet.
	* TODO: revisit to ensure that pass through traffic is not bypassing firewall for fragmented cases
	*/
	if (unlikely(sync_on_find) && !passthrough) {
	/*
	* if we put IP fragmented packets in slow path and non IP fragmented packet in fastpath,
	* this causes out of order pptp sequence number being received at pptp_rcv_core(). So we need to
	* flush the rule for the tunnel which has sequence number to avoid out of order sequence number.
	*/
	if ((gre_hdr->protocol == GRE_PROTO_PPP) && (ntohs(iph->frag_off) & IP_MF)) {
	struct sfe_ipv4_connection *c = cm->connection;
	int ret;

	spin_lock_bh(&si->lock);
	ret = sfe_ipv4_remove_connection(si, c);
	spin_unlock_bh(&si->lock);

	if (ret) {
	sfe_ipv4_flush_connection(si, c, SFE_SYNC_REASON_FLUSH);
	}

	rcu_read_unlock();
	sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_GRE_IP_OPTIONS_OR_INITIAL_FRAGMENT);
	DEBUG_TRACE("%px: sfe: pptp cm flushed\n", cm);
	return 0;
	}

	sfe_ipv4_sync_status(si, cm->connection, SFE_SYNC_REASON_STATS);
	rcu_read_unlock();
	sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_GRE_IP_OPTIONS_OR_INITIAL_FRAGMENT);
	DEBUG_TRACE("%px: sfe: sync on find\n", cm);
	return 0;
	}

	/*
	* Do we expect an ingress VLAN tag for this flow?
	*/
	if (unlikely(!sfe_vlan_validate_ingress_tag(skb, cm->ingress_vlan_hdr_cnt, cm->ingress_vlan_hdr, l2_info))) {
	rcu_read_unlock();
	sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_INGRESS_VLAN_TAG_MISMATCH);
	DEBUG_TRACE("VLAN tag mismatch. skb=%px\n", skb);
	return 0;
	}

	bridge_flow = !!(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_BRIDGE_FLOW);

	/*
	* Does our TTL allow forwarding?
	*/
	ttl = iph->ttl;
	if (!bridge_flow && (ttl < 2) && passthrough) {
	sfe_ipv4_sync_status(si, cm->connection, SFE_SYNC_REASON_STATS);
	rcu_read_unlock();

	DEBUG_TRACE("%px: sfe: TTL too low\n", skb);
	sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_GRE_SMALL_TTL);
	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 1;
	}

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

	/*
	* For PPPoE packets, match server MAC and session id
	*/
	if (unlikely(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_PPPOE_DECAP)) {
	struct ethhdr *eth;
	bool pppoe_match;

	if (unlikely(!sfe_l2_parse_flag_check(l2_info, SFE_L2_PARSE_FLAGS_PPPOE_INGRESS))) {
	rcu_read_unlock();
	DEBUG_TRACE("%px: PPPoE header not present in packet for PPPoE rule\n", skb);
	sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_INCORRECT_PPPOE_PARSING);
	return 0;
	}

	eth = eth_hdr(skb);

	pppoe_match = (cm->pppoe_session_id == sfe_l2_pppoe_session_id_get(l2_info)) &&
	ether_addr_equal((u8)cm->pppoe_remote_mac, (u8 )eth->h_source);

	if (unlikely(!pppoe_match)) {
	DEBUG_TRACE("%px: PPPoE session ID %d and %d or MAC %pM and %pM did not match\n",
	skb, cm->pppoe_session_id, sfe_l2_pppoe_session_id_get(l2_info),
	cm->pppoe_remote_mac, eth->h_source);
	rcu_read_unlock();
	sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_INVALID_PPPOE_SESSION);
	return 0;
	}

	skb->protocol = htons(l2_info->protocol);
	this_cpu_inc(si->stats_pcpu->pppoe_decap_packets_forwarded64);
	} else if (unlikely(sfe_l2_parse_flag_check(l2_info, SFE_L2_PARSE_FLAGS_PPPOE_INGRESS))) {

	/*
	* If packet contains PPPoE header but CME doesn't contain PPPoE flag yet we are exceptioning
	* the packet to linux
	*/
	if (unlikely(!(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_BRIDGE_FLOW))) {
	rcu_read_unlock();
	DEBUG_TRACE("%px: CME doesn't contain PPPoE flag but packet has PPPoE header\n", skb);
	sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_PPPOE_NOT_SET_IN_CME);
	return 0;

	}

	/*
	* For bridged flows when packet contains PPPoE header, restore the header back and forward
	* to xmit interface
	*/
	__skb_push(skb, (sizeof(struct pppoe_hdr) + sizeof(struct sfe_ppp_hdr)));

	this_cpu_inc(si->stats_pcpu->pppoe_bridge_packets_forwarded64);
	}

	/*
	* protocol handler will be valid only in decap-path.
	*/
	if (cm->proto) {
	struct net_protocol *ipprot = cm->proto;
	skb_reset_network_header(skb);
	skb_pull(skb, ihl);
	skb_reset_transport_header(skb);
	skb->fast_forwarded = 1;

	ret = ipprot->handler(skb);
	if (ret) {
	this_cpu_inc(si->stats_pcpu->packets_not_forwarded64);
	rcu_read_unlock();
	DEBUG_TRACE("GRE handler returned error %u\n", ret);
	return 1;
	}

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

	this_cpu_inc(si->stats_pcpu->packets_forwarded64);
	rcu_read_unlock();
	return 1;
	}

	/*
	* Check if skb has enough headroom to write L2 headers
	*/
	if (unlikely(skb_headroom(skb) < cm->l2_hdr_size)) {
	rcu_read_unlock();
	DEBUG_WARN("%px: Not enough headroom: %u\n", skb, skb_headroom(skb));
	sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_NO_HEADROOM);
	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)) {
	sfe_ipv4_sync_status(si, cm->connection, SFE_SYNC_REASON_STATS);
	rcu_read_unlock();
	sfe_ipv4_exception_stats_inc(si, SFE_IPV4_EXCEPTION_EVENT_GRE_NEEDS_FRAGMENTATION);
	DEBUG_TRACE("%px: sfe: larger than MTU\n", cm);
	return 0;
	}

	/*
	* Decrement our TTL
	*/
	iph->ttl = (ttl - (u8)(!bridge_flow && !tun_outer));

	/*
	* Update DSCP
	*/
	if (unlikely(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_DSCP_REMARK)) {
	iph->tos = (iph->tos & SFE_IPV4_DSCP_MASK) \| cm->dscp;
	}

	/*
	* Enable HW csum if rx checksum is verified and xmit interface is CSUM offload capable.
	*/
	hw_csum = !!(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_CSUM_OFFLOAD) && (skb->ip_summed == CHECKSUM_UNNECESSARY);

	/*
	* Replace the IP checksum.
	*/
	if (likely(hw_csum)) {
	skb->ip_summed = CHECKSUM_PARTIAL;
	} else {
	iph->check = sfe_ipv4_gen_ip_csum(iph);
	}

	/*
	* 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;

	/*
	* For PPPoE flows, add PPPoE header before L2 header is added.
	*/
	if (unlikely(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_PPPOE_ENCAP)) {
	sfe_pppoe_add_header(skb, cm->pppoe_session_id, PPP_IP);
	this_cpu_inc(si->stats_pcpu->pppoe_encap_packets_forwarded64);
	}

	/*
	* Check to see if we need to add VLAN tags
	*/
	if (unlikely(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_INSERT_EGRESS_VLAN_TAG)) {
	sfe_vlan_add_tag(skb, cm->egress_vlan_hdr_cnt, cm->egress_vlan_hdr);
	}

	/*
	* For the simple case we write this really fast.
	*/
	if (cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_WRITE_FAST_ETH_HDR) {
	struct ethhdr eth = (struct ethhdr )__skb_push(skb, ETH_HLEN);
	eth->h_proto = skb->protocol;
	ether_addr_copy((u8 )eth->h_dest, (u8 )cm->xmit_dest_mac);
	ether_addr_copy((u8 )eth->h_source, (u8 )cm->xmit_src_mac);
	} else if (cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_WRITE_L2_HDR) {
	dev_hard_header(skb, xmit_dev, ntohs(skb->protocol), cm->xmit_dest_mac, cm->xmit_src_mac, len);
	}

	/*
	* Update priority of skb.
	*/
	if (unlikely(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_PRIORITY_REMARK)) {
	skb->priority = cm->priority;
	}

	/*
	* Mark outgoing packet.
	*/
	if (unlikely(cm->flags & SFE_IPV4_CONNECTION_MATCH_FLAG_MARK)) {
	skb->mark = cm->mark;
	}

	this_cpu_inc(si->stats_pcpu->packets_forwarded64);

	rcu_read_unlock();

	/*
	* 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;
	}