text: /*
   * Copyright (c) 2007-2015 Nicira, Inc.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of version 2 of the GNU General Public
   * License as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   * 02110-1301, USA
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/skbuff.h>
  #include <linux/in.h>
  #include <linux/ip.h>
  #include <linux/openvswitch.h>
  #include <linux/netfilter_ipv6.h>
  #include <linux/sctp.h>
  #include <linux/tcp.h>
  #include <linux/udp.h>
  #include <linux/in6.h>
  #include <linux/if_arp.h>
  #include <linux/if_vlan.h>
  
  #include <net/dst.h>
  #include <net/ip.h>
  #include <net/ipv6.h>
  #include <net/checksum.h>
  #include <net/dsfield.h>
  #include <net/mpls.h>
  #include <net/sctp/checksum.h>
  
  #include "datapath.h"
  #include "conntrack.h"
  #include "gso.h"
  #include "vport.h"
  
  static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
  			      struct sw_flow_key *key,
  			      const struct nlattr *attr, int len);
  
  struct deferred_action {
  	struct sk_buff *skb;
  	const struct nlattr *actions;
  
  	/* Store pkt_key clone when creating deferred action. */
  	struct sw_flow_key pkt_key;
  };
  
  #define MAX_L2_LEN	(VLAN_ETH_HLEN + 3 * MPLS_HLEN)
  struct ovs_frag_data {
  	unsigned long dst;
  	struct vport *vport;
  	struct ovs_gso_cb cb;
  	__be16 inner_protocol;
  	__u16 vlan_tci;
  	__be16 vlan_proto;
  	unsigned int l2_len;
  	u8 mac_proto;
  	u8 l2_data[MAX_L2_LEN];
  };
  
  static DEFINE_PER_CPU(struct ovs_frag_data, ovs_frag_data_storage);
  
  #define DEFERRED_ACTION_FIFO_SIZE 10
  #define OVS_RECURSION_LIMIT 4
  #define OVS_DEFERRED_ACTION_THRESHOLD (OVS_RECURSION_LIMIT - 2)
  struct action_fifo {
  	int head;
  	int tail;
  	/* Deferred action fifo queue storage. */
  	struct deferred_action fifo[DEFERRED_ACTION_FIFO_SIZE];
  };
  
  struct recirc_keys {
  	struct sw_flow_key key[OVS_DEFERRED_ACTION_THRESHOLD];
  };
  
  static struct action_fifo __percpu *action_fifos;
  static struct recirc_keys __percpu *recirc_keys;
  static DEFINE_PER_CPU(int, exec_actions_level);
  
  static void action_fifo_init(struct action_fifo *fifo)
  {
  	fifo->head = 0;
  	fifo->tail = 0;
  }
  
  static bool action_fifo_is_empty(const struct action_fifo *fifo)
  {
  	return (fifo->head == fifo->tail);
  }
  
  static struct deferred_action *action_fifo_get(struct action_fifo *fifo)
  {
  	if (action_fifo_is_empty(fifo))
  		return NULL;
  
  	return &fifo->fifo[fifo->tail++];
  }
  
  static struct deferred_action *action_fifo_put(struct action_fifo *fifo)
  {
  	if (fifo->head >= DEFERRED_ACTION_FIFO_SIZE - 1)
  		return NULL;
  
  	return &fifo->fifo[fifo->head++];
  }
  
  /* Return queue entry if fifo is not full */
  static struct deferred_action *add_deferred_actions(struct sk_buff *skb,
  						    const struct sw_flow_key *key,
  						    const struct nlattr *attr)
  {
  	struct action_fifo *fifo;
  	struct deferred_action *da;
  
  	fifo = this_cpu_ptr(action_fifos);
  	da = action_fifo_put(fifo);
  	if (da) {
  		da->skb = skb;
  		da->actions = attr;
  		da->pkt_key = *key;
  	}
  
  	return da;
  }
  
  static void invalidate_flow_key(struct sw_flow_key *key)
  {
  	key->mac_proto |= SW_FLOW_KEY_INVALID;
  }
  
  static bool is_flow_key_valid(const struct sw_flow_key *key)
  {
  	return !(key->mac_proto & SW_FLOW_KEY_INVALID);
  }
  
  static void update_ethertype(struct sk_buff *skb, struct ethhdr *hdr,
  			     __be16 ethertype)
  {
  	if (skb->ip_summed == CHECKSUM_COMPLETE) {
  		__be16 diff[] = { ~(hdr->h_proto), ethertype };
  
  		skb->csum = ~csum_partial((char *)diff, sizeof(diff),
  					~skb->csum);
  	}
  
  	hdr->h_proto = ethertype;
  }
  
  static int push_mpls(struct sk_buff *skb, struct sw_flow_key *key,
  		     const struct ovs_action_push_mpls *mpls)
  {
  	__be32 *new_mpls_lse;
  
  	/* Networking stack do not allow simultaneous Tunnel and MPLS GSO. */
  	if (skb->encapsulation)
  		return -ENOTSUPP;
  
  	if (skb_cow_head(skb, MPLS_HLEN) < 0)
  		return -ENOMEM;
  
  	skb_push(skb, MPLS_HLEN);
  	memmove(skb_mac_header(skb) - MPLS_HLEN, skb_mac_header(skb),
  		skb->mac_len);
  	skb_reset_mac_header(skb);
  
  	new_mpls_lse = (__be32 *)skb_mpls_header(skb);
  	*new_mpls_lse = mpls->mpls_lse;
  
  	skb_postpush_rcsum(skb, new_mpls_lse, MPLS_HLEN);
  
  	if (ovs_key_mac_proto(key) == MAC_PROTO_ETHERNET)
  		update_ethertype(skb, eth_hdr(skb), mpls->mpls_ethertype);
  	if (!ovs_skb_get_inner_protocol(skb))
  		ovs_skb_set_inner_protocol(skb, skb->protocol);
  	skb->protocol = mpls->mpls_ethertype;
  
  	invalidate_flow_key(key);
  	return 0;
  }
  
  static int pop_mpls(struct sk_buff *skb, struct sw_flow_key *key,
  		    const __be16 ethertype)
  {
  	int err;
  
  	err = skb_ensure_writable(skb, skb->mac_len + MPLS_HLEN);
  	if (unlikely(err))
  		return err;
  
  	skb_postpull_rcsum(skb, skb_mpls_header(skb), MPLS_HLEN);
  
  	memmove(skb_mac_header(skb) + MPLS_HLEN, skb_mac_header(skb),
  		skb->mac_len);
  
  	__skb_pull(skb, MPLS_HLEN);
  	skb_reset_mac_header(skb);
  
  	if (ovs_key_mac_proto(key) == MAC_PROTO_ETHERNET) {
  		struct ethhdr *hdr;
  
  		/* skb_mpls_header() is used to locate the ethertype
  		 * field correctly in the presence of VLAN tags.
  		 */
  		hdr = (struct ethhdr *)(skb_mpls_header(skb) - ETH_HLEN);
  		update_ethertype(skb, hdr, ethertype);
          }
  	if (eth_p_mpls(skb->protocol))
  		skb->protocol = ethertype;
  
  	invalidate_flow_key(key);
  	return 0;
  }
  
  static int set_mpls(struct sk_buff *skb, struct sw_flow_key *flow_key,
  		    const __be32 *mpls_lse, const __be32 *mask)
  {
  	__be32 *stack;
  	__be32 lse;
  	int err;
  
  	err = skb_ensure_writable(skb, skb->mac_len + MPLS_HLEN);
  	if (unlikely(err))
  		return err;
  
  	stack = (__be32 *)skb_mpls_header(skb);
  	lse = OVS_MASKED(*stack, *mpls_lse, *mask);
  	if (skb->ip_summed == CHECKSUM_COMPLETE) {
  		__be32 diff[] = { ~(*stack), lse };
  
  		skb->csum = ~csum_partial((char *)diff, sizeof(diff),
  					  ~skb->csum);
  	}
  
  	*stack = lse;
  	flow_key->mpls.top_lse = lse;
  	return 0;
  }
  
  static int pop_vlan(struct sk_buff *skb, struct sw_flow_key *key)
  {
  	int err;
  
  	err = skb_vlan_pop(skb);
  	if (skb_vlan_tag_present(skb)) {
  		invalidate_flow_key(key);
  	} else {
  		key->eth.vlan.tci = 0;
  		key->eth.vlan.tpid = 0;
  	}
  	return err;
  }
  
  static int push_vlan(struct sk_buff *skb, struct sw_flow_key *key,
  		     const struct ovs_action_push_vlan *vlan)
  {
  	if (skb_vlan_tag_present(skb)) {
  		invalidate_flow_key(key);
  	} else {
  		key->eth.vlan.tci = vlan->vlan_tci;
  		key->eth.vlan.tpid = vlan->vlan_tpid;
  	}
  	return skb_vlan_push(skb, vlan->vlan_tpid,
  			     ntohs(vlan->vlan_tci) & ~VLAN_TAG_PRESENT);
  }
  
  /* 'src' is already properly masked. */
  static void ether_addr_copy_masked(u8 *dst_, const u8 *src_, const u8 *mask_)
  {
  	u16 *dst = (u16 *)dst_;
  	const u16 *src = (const u16 *)src_;
  	const u16 *mask = (const u16 *)mask_;
  
  	OVS_SET_MASKED(dst[0], src[0], mask[0]);
  	OVS_SET_MASKED(dst[1], src[1], mask[1]);
  	OVS_SET_MASKED(dst[2], src[2], mask[2]);
  }
  
  static int set_eth_addr(struct sk_buff *skb, struct sw_flow_key *flow_key,
  			const struct ovs_key_ethernet *key,
  			const struct ovs_key_ethernet *mask)
  {
  	int err;
  
  	err = skb_ensure_writable(skb, ETH_HLEN);
  	if (unlikely(err))
  		return err;
  
  	skb_postpull_rcsum(skb, eth_hdr(skb), ETH_ALEN * 2);
  
  	ether_addr_copy_masked(eth_hdr(skb)->h_source, key->eth_src,
  			       mask->eth_src);
  	ether_addr_copy_masked(eth_hdr(skb)->h_dest, key->eth_dst,
  			       mask->eth_dst);
  
  	skb_postpush_rcsum(skb, eth_hdr(skb), ETH_ALEN * 2);
  
  	ether_addr_copy(flow_key->eth.src, eth_hdr(skb)->h_source);
  	ether_addr_copy(flow_key->eth.dst, eth_hdr(skb)->h_dest);
  	return 0;
  }
  
  /* pop_eth does not support VLAN packets as this action is never called
   * for them.
   */
  static int pop_eth(struct sk_buff *skb, struct sw_flow_key *key)
  {
  	skb_pull_rcsum(skb, ETH_HLEN);
  	skb_reset_mac_header(skb);
  	skb_reset_mac_len(skb);
  
  	/* safe right before invalidate_flow_key */
  	key->mac_proto = MAC_PROTO_NONE;
  	invalidate_flow_key(key);
  	return 0;
  }
  
  static int push_eth(struct sk_buff *skb, struct sw_flow_key *key,
  		    const struct ovs_action_push_eth *ethh)
  {
  	struct ethhdr *hdr;
  
  	/* Add the new Ethernet header */
  	if (skb_cow_head(skb, ETH_HLEN) < 0)
  		return -ENOMEM;
  
  	skb_push(skb, ETH_HLEN);
  	skb_reset_mac_header(skb);
  	skb_reset_mac_len(skb);
  
  	hdr = eth_hdr(skb);
  	ether_addr_copy(hdr->h_source, ethh->addresses.eth_src);
  	ether_addr_copy(hdr->h_dest, ethh->addresses.eth_dst);
  	hdr->h_proto = skb->protocol;
  
  	skb_postpush_rcsum(skb, hdr, ETH_HLEN);
  
  	/* safe right before invalidate_flow_key */
  	key->mac_proto = MAC_PROTO_ETHERNET;
  	invalidate_flow_key(key);
  	return 0;
  }
  
  static void update_ip_l4_checksum(struct sk_buff *skb, struct iphdr *nh,
  				  __be32 addr, __be32 new_addr)
  {
  	int transport_len = skb->len - skb_transport_offset(skb);
  
  	if (nh->frag_off & htons(IP_OFFSET))
  		return;
  
  	if (nh->protocol == IPPROTO_TCP) {
  		if (likely(transport_len >= sizeof(struct tcphdr)))
  			inet_proto_csum_replace4(&tcp_hdr(skb)->check, skb,
  						 addr, new_addr, true);
  	} else if (nh->protocol == IPPROTO_UDP) {
  		if (likely(transport_len >= sizeof(struct udphdr))) {
  			struct udphdr *uh = udp_hdr(skb);
  
  			if (uh->check || skb->ip_summed == CHECKSUM_PARTIAL) {
  				inet_proto_csum_replace4(&uh->check, skb,
  							 addr, new_addr, true);
  				if (!uh->check)
  					uh->check = CSUM_MANGLED_0;
  			}
  		}
  	}
  
  }
  
  static void set_ip_addr(struct sk_buff *skb, struct iphdr *nh,
  			__be32 *addr, __be32 new_addr)
  {
  	update_ip_l4_checksum(skb, nh, *addr, new_addr);
  	csum_replace4(&nh->check, *addr, new_addr);
  	skb_clear_hash(skb);
  	*addr = new_addr;
  }
  
  static void update_ipv6_checksum(struct sk_buff *skb, u8 l4_proto,
  				 __be32 addr[4], const __be32 new_addr[4])
  {
  	int transport_len = skb->len - skb_transport_offset(skb);
  
  	if (l4_proto == NEXTHDR_TCP) {
  		if (likely(transport_len >= sizeof(struct tcphdr)))
  			inet_proto_csum_replace16(&tcp_hdr(skb)->check, skb,
  						  addr, new_addr, true);
  	} else if (l4_proto == NEXTHDR_UDP) {
  		if (likely(transport_len >= sizeof(struct udphdr))) {
  			struct udphdr *uh = udp_hdr(skb);
  
  			if (uh->check || skb->ip_summed == CHECKSUM_PARTIAL) {
  				inet_proto_csum_replace16(&uh->check, skb,
  							  addr, new_addr, true);
  				if (!uh->check)
  					uh->check = CSUM_MANGLED_0;
  			}
  		}
  	} else if (l4_proto == NEXTHDR_ICMP) {
  		if (likely(transport_len >= sizeof(struct icmp6hdr)))
  			inet_proto_csum_replace16(&icmp6_hdr(skb)->icmp6_cksum,
  						  skb, addr, new_addr, true);
  	}
  }
  
  static void mask_ipv6_addr(const __be32 old[4], const __be32 addr[4],
  			   const __be32 mask[4], __be32 masked[4])
  {
  	masked[0] = OVS_MASKED(old[0], addr[0], mask[0]);
  	masked[1] = OVS_MASKED(old[1], addr[1], mask[1]);
  	masked[2] = OVS_MASKED(old[2], addr[2], mask[2]);
  	masked[3] = OVS_MASKED(old[3], addr[3], mask[3]);
  }
  
  static void set_ipv6_addr(struct sk_buff *skb, u8 l4_proto,
  			  __be32 addr[4], const __be32 new_addr[4],
  			  bool recalculate_csum)
  {
  	if (likely(recalculate_csum))
  		update_ipv6_checksum(skb, l4_proto, addr, new_addr);
  
  	skb_clear_hash(skb);
  	memcpy(addr, new_addr, sizeof(__be32[4]));
  }
  
  static void set_ipv6_fl(struct ipv6hdr *nh, u32 fl, u32 mask)
  {
  	/* Bits 21-24 are always unmasked, so this retains their values. */
  	OVS_SET_MASKED(nh->flow_lbl[0], (u8)(fl >> 16), (u8)(mask >> 16));
  	OVS_SET_MASKED(nh->flow_lbl[1], (u8)(fl >> 8), (u8)(mask >> 8));
  	OVS_SET_MASKED(nh->flow_lbl[2], (u8)fl, (u8)mask);
  }
  
  static void set_ip_ttl(struct sk_buff *skb, struct iphdr *nh, u8 new_ttl,
  		       u8 mask)
  {
  	new_ttl = OVS_MASKED(nh->ttl, new_ttl, mask);
  
  	csum_replace2(&nh->check, htons(nh->ttl << 8), htons(new_ttl << 8));
  	nh->ttl = new_ttl;
  }
  
  static int set_ipv4(struct sk_buff *skb, struct sw_flow_key *flow_key,
  		    const struct ovs_key_ipv4 *key,
  		    const struct ovs_key_ipv4 *mask)
  {
  	struct iphdr *nh;
  	__be32 new_addr;
  	int err;
  
  	err = skb_ensure_writable(skb, skb_network_offset(skb) +
  				  sizeof(struct iphdr));
  	if (unlikely(err))
  		return err;
  
  	nh = ip_hdr(skb);
  
  	/* Setting an IP addresses is typically only a side effect of
  	 * matching on them in the current userspace implementation, so it
  	 * makes sense to check if the value actually changed.
  	 */
  	if (mask->ipv4_src) {
  		new_addr = OVS_MASKED(nh->saddr, key->ipv4_src, mask->ipv4_src);
  
  		if (unlikely(new_addr != nh->saddr)) {
  			set_ip_addr(skb, nh, &nh->saddr, new_addr);
  			flow_key->ipv4.addr.src = new_addr;
  		}
  	}
  	if (mask->ipv4_dst) {
  		new_addr = OVS_MASKED(nh->daddr, key->ipv4_dst, mask->ipv4_dst);
  
  		if (unlikely(new_addr != nh->daddr)) {
  			set_ip_addr(skb, nh, &nh->daddr, new_addr);
  			flow_key->ipv4.addr.dst = new_addr;
  		}
  	}
  	if (mask->ipv4_tos) {
  		ipv4_change_dsfield(nh, ~mask->ipv4_tos, key->ipv4_tos);
  		flow_key->ip.tos = nh->tos;
  	}
  	if (mask->ipv4_ttl) {
  		set_ip_ttl(skb, nh, key->ipv4_ttl, mask->ipv4_ttl);
  		flow_key->ip.ttl = nh->ttl;
  	}
  
  	return 0;
  }
  
  static bool is_ipv6_mask_nonzero(const __be32 addr[4])
  {
  	return !!(addr[0] | addr[1] | addr[2] | addr[3]);
  }
  
  static int set_ipv6(struct sk_buff *skb, struct sw_flow_key *flow_key,
  		    const struct ovs_key_ipv6 *key,
  		    const struct ovs_key_ipv6 *mask)
  {
  	struct ipv6hdr *nh;
  	int err;
  
  	err = skb_ensure_writable(skb, skb_network_offset(skb) +
  				  sizeof(struct ipv6hdr));
  	if (unlikely(err))
  		return err;
  
  	nh = ipv6_hdr(skb);
  
  	/* Setting an IP addresses is typically only a side effect of
  	 * matching on them in the current userspace implementation, so it
  	 * makes sense to check if the value actually changed.
  	 */
  	if (is_ipv6_mask_nonzero(mask->ipv6_src)) {
  		__be32 *saddr = (__be32 *)&nh->saddr;
  		__be32 masked[4];
  
  		mask_ipv6_addr(saddr, key->ipv6_src, mask->ipv6_src, masked);
  
  		if (unlikely(memcmp(saddr, masked, sizeof(masked)))) {
  			set_ipv6_addr(skb, flow_key->ip.proto, saddr, masked,
  				      true);
  			memcpy(&flow_key->ipv6.addr.src, masked,
  			       sizeof(flow_key->ipv6.addr.src));
  		}
  	}
  	if (is_ipv6_mask_nonzero(mask->ipv6_dst)) {
  		unsigned int offset = 0;
  		int flags = IP6_FH_F_SKIP_RH;
  		bool recalc_csum = true;
  		__be32 *daddr = (__be32 *)&nh->daddr;
  		__be32 masked[4];
  
  		mask_ipv6_addr(daddr, key->ipv6_dst, mask->ipv6_dst, masked);
  
  		if (unlikely(memcmp(daddr, masked, sizeof(masked)))) {
  			if (ipv6_ext_hdr(nh->nexthdr))
  				recalc_csum = (ipv6_find_hdr(skb, &offset,
  							     NEXTHDR_ROUTING,
  							     NULL, &flags)
  					       != NEXTHDR_ROUTING);
  
  			set_ipv6_addr(skb, flow_key->ip.proto, daddr, masked,
  				      recalc_csum);
  			memcpy(&flow_key->ipv6.addr.dst, masked,
  			       sizeof(flow_key->ipv6.addr.dst));
  		}
  	}
  	if (mask->ipv6_tclass) {
  		ipv6_change_dsfield(nh, ~mask->ipv6_tclass, key->ipv6_tclass);
  		flow_key->ip.tos = ipv6_get_dsfield(nh);
  	}
  	if (mask->ipv6_label) {
  		set_ipv6_fl(nh, ntohl(key->ipv6_label),
  			    ntohl(mask->ipv6_label));
  		flow_key->ipv6.label =
  		    *(__be32 *)nh & htonl(IPV6_FLOWINFO_FLOWLABEL);
  	}
  	if (mask->ipv6_hlimit) {
  		OVS_SET_MASKED(nh->hop_limit, key->ipv6_hlimit,
  			       mask->ipv6_hlimit);
  		flow_key->ip.ttl = nh->hop_limit;
  	}
  	return 0;
  }
  
  /* Must follow skb_ensure_writable() since that can move the skb data. */
  static void set_tp_port(struct sk_buff *skb, __be16 *port,
  			__be16 new_port, __sum16 *check)
  {
  	inet_proto_csum_replace2(check, skb, *port, new_port, false);
  	*port = new_port;
  }
  
  static int set_udp(struct sk_buff *skb, struct sw_flow_key *flow_key,
  		   const struct ovs_key_udp *key,
  		   const struct ovs_key_udp *mask)
  {
  	struct udphdr *uh;
  	__be16 src, dst;
  	int err;
  
  	err = skb_ensure_writable(skb, skb_transport_offset(skb) +
  				  sizeof(struct udphdr));
  	if (unlikely(err))
  		return err;
  
  	uh = udp_hdr(skb);
  	/* Either of the masks is non-zero, so do not bother checking them. */
  	src = OVS_MASKED(uh->source, key->udp_src, mask->udp_src);
  	dst = OVS_MASKED(uh->dest, key->udp_dst, mask->udp_dst);
  
  	if (uh->check && skb->ip_summed != CHECKSUM_PARTIAL) {
  		if (likely(src != uh->source)) {
  			set_tp_port(skb, &uh->source, src, &uh->check);
  			flow_key->tp.src = src;
  		}
  		if (likely(dst != uh->dest)) {
  			set_tp_port(skb, &uh->dest, dst, &uh->check);
  			flow_key->tp.dst = dst;
  		}
  
  		if (unlikely(!uh->check))
  			uh->check = CSUM_MANGLED_0;
  	} else {
  		uh->source = src;
  		uh->dest = dst;
  		flow_key->tp.src = src;
  		flow_key->tp.dst = dst;
  	}
  
  	skb_clear_hash(skb);
  
  	return 0;
  }
  
  static int set_tcp(struct sk_buff *skb, struct sw_flow_key *flow_key,
  		   const struct ovs_key_tcp *key,
  		   const struct ovs_key_tcp *mask)
  {
  	struct tcphdr *th;
  	__be16 src, dst;
  	int err;
  
  	err = skb_ensure_writable(skb, skb_transport_offset(skb) +
  				  sizeof(struct tcphdr));
  	if (unlikely(err))
  		return err;
  
  	th = tcp_hdr(skb);
  	src = OVS_MASKED(th->source, key->tcp_src, mask->tcp_src);
  	if (likely(src != th->source)) {
  		set_tp_port(skb, &th->source, src, &th->check);
  		flow_key->tp.src = src;
  	}
  	dst = OVS_MASKED(th->dest, key->tcp_dst, mask->tcp_dst);
  	if (likely(dst != th->dest)) {
  		set_tp_port(skb, &th->dest, dst, &th->check);
  		flow_key->tp.dst = dst;
  	}
  	skb_clear_hash(skb);
  
  	return 0;
  }
  
  static int set_sctp(struct sk_buff *skb, struct sw_flow_key *flow_key,
  		    const struct ovs_key_sctp *key,
  		    const struct ovs_key_sctp *mask)
  {
  	unsigned int sctphoff = skb_transport_offset(skb);
  	struct sctphdr *sh;
  	__le32 old_correct_csum, new_csum, old_csum;
  	int err;
  
  	err = skb_ensure_writable(skb, sctphoff + sizeof(struct sctphdr));
  	if (unlikely(err))
  		return err;
  
  	sh = sctp_hdr(skb);
  	old_csum = sh->checksum;
  	old_correct_csum = sctp_compute_cksum(skb, sctphoff);
  
  	sh->source = OVS_MASKED(sh->source, key->sctp_src, mask->sctp_src);
  	sh->dest = OVS_MASKED(sh->dest, key->sctp_dst, mask->sctp_dst);
  
  	new_csum = sctp_compute_cksum(skb, sctphoff);
  
  	/* Carry any checksum errors through. */
  	sh->checksum = old_csum ^ old_correct_csum ^ new_csum;
  
  	skb_clear_hash(skb);
  	flow_key->tp.src = sh->source;
  	flow_key->tp.dst = sh->dest;
  
  	return 0;
  }
  
  static int ovs_vport_output(OVS_VPORT_OUTPUT_PARAMS)
  {
  	struct ovs_frag_data *data = this_cpu_ptr(&ovs_frag_data_storage);
  	struct vport *vport = data->vport;
  
  	if (skb_cow_head(skb, data->l2_len) < 0) {
  		kfree_skb(skb);
  		return -ENOMEM;
  	}
  
  	__skb_dst_copy(skb, data->dst);
  	*OVS_GSO_CB(skb) = data->cb;
  	ovs_skb_set_inner_protocol(skb, data->inner_protocol);
  	skb->vlan_tci = data->vlan_tci;
  	skb->vlan_proto = data->vlan_proto;
  
  	/* Reconstruct the MAC header.  */
  	skb_push(skb, data->l2_len);
  	memcpy(skb->data, &data->l2_data, data->l2_len);
  	skb_postpush_rcsum(skb, skb->data, data->l2_len);
  	skb_reset_mac_header(skb);
  
  	ovs_vport_send(vport, skb, data->mac_proto);
  	return 0;
  }
  
  static unsigned int
  ovs_dst_get_mtu(const struct dst_entry *dst)
  {
  	return dst->dev->mtu;
  }
  
  static struct dst_ops ovs_dst_ops = {
  	.family = AF_UNSPEC,
  	.mtu = ovs_dst_get_mtu,
  };
  
  /* prepare_frag() is called once per (larger-than-MTU) frame; its inverse is
   * ovs_vport_output(), which is called once per fragmented packet.
   */
  static void prepare_frag(struct vport *vport, struct sk_buff *skb,
  			u8 mac_proto)
  {
  	unsigned int hlen = skb_network_offset(skb);
  	struct ovs_frag_data *data;
  
  	data = this_cpu_ptr(&ovs_frag_data_storage);
  	data->dst = (unsigned long) skb_dst(skb);
  	data->vport = vport;
  	data->cb = *OVS_GSO_CB(skb);
  	data->inner_protocol = ovs_skb_get_inner_protocol(skb);
  	data->vlan_tci = skb->vlan_tci;
  	data->vlan_proto = skb->vlan_proto;
  	data->mac_proto = mac_proto;
  	data->l2_len = hlen;
  	memcpy(&data->l2_data, skb->data, hlen);
  
  	memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
  	skb_pull(skb, hlen);
  }
  
  static void ovs_fragment(struct net *net, struct vport *vport,
  			 struct sk_buff *skb, u16 mru,
  			 struct sw_flow_key *key)
  {
  	if (skb_network_offset(skb) > MAX_L2_LEN) {
  		OVS_NLERR(1, "L2 header too long to fragment");
  		goto err;
  	}
  
  	if (key->eth.type == htons(ETH_P_IP)) {
  		struct dst_entry ovs_dst;
  		unsigned long orig_dst;
  
  		prepare_frag(vport, skb, ovs_key_mac_proto(key));
  		dst_init(&ovs_dst, &ovs_dst_ops, NULL, 1,
  			 DST_OBSOLETE_NONE, DST_NOCOUNT);
  		ovs_dst.dev = vport->dev;
  
  		orig_dst = (unsigned long) skb_dst(skb);
  		skb_dst_set_noref(skb, &ovs_dst);
  		IPCB(skb)->frag_max_size = mru;
  
  		ip_do_fragment(net, skb->sk, skb, ovs_vport_output);
  		refdst_drop(orig_dst);
  	} else if (key->eth.type == htons(ETH_P_IPV6)) {
  		const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
  		unsigned long orig_dst;
  		struct rt6_info ovs_rt;
  
  		if (!v6ops) {
  			goto err;
  		}
  
  		prepare_frag(vport, skb,
  			     ovs_key_mac_proto(key));
  		memset(&ovs_rt, 0, sizeof(ovs_rt));
  		dst_init(&ovs_rt.dst, &ovs_dst_ops, NULL, 1,
  			 DST_OBSOLETE_NONE, DST_NOCOUNT);
  		ovs_rt.dst.dev = vport->dev;
  
  		orig_dst = (unsigned long) skb_dst(skb);
  		skb_dst_set_noref(skb, &ovs_rt.dst);
  		IP6CB(skb)->frag_max_size = mru;
  #ifdef HAVE_IP_LOCAL_OUT_TAKES_NET
  		v6ops->fragment(net, skb->sk, skb, ovs_vport_output);
  #else
  		v6ops->fragment(skb->sk, skb, ovs_vport_output);
  #endif
  		refdst_drop(orig_dst);
  	} else {
  		WARN_ONCE(1, "Failed fragment ->%s: eth=%04x, MRU=%d, MTU=%d.",
  			  ovs_vport_name(vport), ntohs(key->eth.type), mru,
  			  vport->dev->mtu);
  		goto err;
  	}
  
  	return;
  err:
  	kfree_skb(skb);
  }
  
  static void do_output(struct datapath *dp, struct sk_buff *skb, int out_port,
  		      struct sw_flow_key *key)
  {
  	struct vport *vport = ovs_vport_rcu(dp, out_port);
  
  	if (likely(vport)) {
  		u16 mru = OVS_CB(skb)->mru;
  		u32 cutlen = OVS_CB(skb)->cutlen;
  
  		if (unlikely(cutlen > 0)) {
  			if (skb->len - cutlen > ovs_mac_header_len(key))
  				pskb_trim(skb, skb->len - cutlen);
  			else
  				pskb_trim(skb, ovs_mac_header_len(key));
  		}
  
  		if (likely(!mru ||
  		           (skb->len <= mru + vport->dev->hard_header_len))) {
  			ovs_vport_send(vport, skb, ovs_key_mac_proto(key));
  		} else if (mru <= vport->dev->mtu) {
  			struct net *net = ovs_dp_get_net(dp);
  
                          ovs_fragment(net, vport, skb, mru, key);
  		} else {
  			OVS_NLERR(true, "Cannot fragment IP frames");
  			kfree_skb(skb);
  		}
  	} else {
  		kfree_skb(skb);
  	}
  }
  
  static int output_userspace(struct datapath *dp, struct sk_buff *skb,
  			    struct sw_flow_key *key, const struct nlattr *attr,
  			    const struct nlattr *actions, int actions_len,
  			    uint32_t cutlen)
  {
  	struct dp_upcall_info upcall;
  	const struct nlattr *a;
  	int rem, err;
  
  	memset(&upcall, 0, sizeof(upcall));
  	upcall.cmd = OVS_PACKET_CMD_ACTION;
  	upcall.mru = OVS_CB(skb)->mru;
  
  	SKB_INIT_FILL_METADATA_DST(skb);
  	for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
  		 a = nla_next(a, &rem)) {
  		switch (nla_type(a)) {
  		case OVS_USERSPACE_ATTR_USERDATA:
  			upcall.userdata = a;
  			break;
  
  		case OVS_USERSPACE_ATTR_PID:
  			upcall.portid = nla_get_u32(a);
  			break;
  
  		case OVS_USERSPACE_ATTR_EGRESS_TUN_PORT: {
  			/* Get out tunnel info. */
  			struct vport *vport;
  
  			vport = ovs_vport_rcu(dp, nla_get_u32(a));
  			if (vport) {
  				err = dev_fill_metadata_dst(vport->dev, skb);
  				if (!err)
  					upcall.egress_tun_info = skb_tunnel_info(skb);
  			}
  
  			break;
  		}
  
  		case OVS_USERSPACE_ATTR_ACTIONS: {
  			/* Include actions. */
  			upcall.actions = actions;
  			upcall.actions_len = actions_len;
  			break;
  		}
  
  		} /* End of switch. */
  	}
  
  	err = ovs_dp_upcall(dp, skb, key, &upcall, cutlen);
  	SKB_RESTORE_FILL_METADATA_DST(skb);
  	return err;
  }
  
  static int sample(struct datapath *dp, struct sk_buff *skb,
  		  struct sw_flow_key *key, const struct nlattr *attr,
  		  const struct nlattr *actions, int actions_len)
  {
  	const struct nlattr *acts_list = NULL;
  	const struct nlattr *a;
  	int rem;
  	u32 cutlen = 0;
  
  	for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
  		 a = nla_next(a, &rem)) {
  		u32 probability;
  
  		switch (nla_type(a)) {
  		case OVS_SAMPLE_ATTR_PROBABILITY:
  			probability = nla_get_u32(a);
  			if (!probability || prandom_u32() > probability)
  				return 0;
  			break;
  
  		case OVS_SAMPLE_ATTR_ACTIONS:
  			acts_list = a;
  			break;
  		}
  	}
  
  	rem = nla_len(acts_list);
  	a = nla_data(acts_list);
  
  	/* Actions list is empty, do nothing */
  	if (unlikely(!rem))
  		return 0;
  
  	/* The only known usage of sample action is having a single user-space
  	 * action, or having a truncate action followed by a single user-space
  	 * action. Treat this usage as a special case.
  	 * The output_userspace() should clone the skb to be sent to the
  	 * user space. This skb will be consumed by its caller.
  	 */
  	if (unlikely(nla_type(a) == OVS_ACTION_ATTR_TRUNC)) {
  		struct ovs_action_trunc *trunc = nla_data(a);
  
  		if (skb->len > trunc->max_len)
  			cutlen = skb->len - trunc->max_len;
  
  		a = nla_next(a, &rem);
  	}
  
  	if (likely(nla_type(a) == OVS_ACTION_ATTR_USERSPACE &&
  		   nla_is_last(a, rem)))
  		return output_userspace(dp, skb, key, a, actions,
  					actions_len, cutlen);
  
  	skb = skb_clone(skb, GFP_ATOMIC);
  	if (!skb)
  		/* Skip the sample action when out of memory. */
  		return 0;
  
  	if (!add_deferred_actions(skb, key, a)) {
  		if (net_ratelimit())
  			pr_warn("%s: deferred actions limit reached, dropping sample action\n",
  				ovs_dp_name(dp));
  
  		kfree_skb(skb);
  	}
  	return 0;
  }
  
  static void execute_hash(struct sk_buff *skb, struct sw_flow_key *key,
  			 const struct nlattr *attr)
  {
  	struct ovs_action_hash *hash_act = nla_data(attr);
  	u32 hash = 0;
  
  	/* OVS_HASH_ALG_L4 is the only possible hash algorithm.  */
  	hash = skb_get_hash(skb);
  	hash = jhash_1word(hash, hash_act->hash_basis);
  	if (!hash)
  		hash = 0x1;
  
  	key->ovs_flow_hash = hash;
  }
  
  static int execute_set_action(struct sk_buff *skb,
  			      struct sw_flow_key *flow_key,
  			      const struct nlattr *a)
  {
  	/* Only tunnel set execution is supported without a mask. */
  	if (nla_type(a) == OVS_KEY_ATTR_TUNNEL_INFO) {
  		struct ovs_tunnel_info *tun = nla_data(a);
  
  		ovs_skb_dst_drop(skb);
  		ovs_dst_hold((struct dst_entry *)tun->tun_dst);
  		ovs_skb_dst_set(skb, (struct dst_entry *)tun->tun_dst);
  		return 0;
  	}
  
  	return -EINVAL;
  }
  
  /* Mask is at the midpoint of the data. */
  #define get_mask(a, type) ((const type)nla_data(a) + 1)
  
  static int execute_masked_set_action(struct sk_buff *skb,
  				     struct sw_flow_key *flow_key,
  				     const struct nlattr *a)
  {
  	int err = 0;
  
  	switch (nla_type(a)) {
  	case OVS_KEY_ATTR_PRIORITY:
  		OVS_SET_MASKED(skb->priority, nla_get_u32(a),
  			       *get_mask(a, u32 *));
  		flow_key->phy.priority = skb->priority;
  		break;
  
  	case OVS_KEY_ATTR_SKB_MARK:
  		OVS_SET_MASKED(skb->mark, nla_get_u32(a), *get_mask(a, u32 *));
  		flow_key->phy.skb_mark = skb->mark;
  		break;
  
  	case OVS_KEY_ATTR_TUNNEL_INFO:
  		/* Masked data not supported for tunnel. */
  		err = -EINVAL;
  		break;
  
  	case OVS_KEY_ATTR_ETHERNET:
  		err = set_eth_addr(skb, flow_key, nla_data(a),
  				   get_mask(a, struct ovs_key_ethernet *));
  		break;
  
  	case OVS_KEY_ATTR_IPV4:
  		err = set_ipv4(skb, flow_key, nla_data(a),
  			       get_mask(a, struct ovs_key_ipv4 *));
  		break;
  
  	case OVS_KEY_ATTR_IPV6:
  		err = set_ipv6(skb, flow_key, nla_data(a),
  			       get_mask(a, struct ovs_key_ipv6 *));
  		break;
  
  	case OVS_KEY_ATTR_TCP:
  		err = set_tcp(skb, flow_key, nla_data(a),
  			      get_mask(a, struct ovs_key_tcp *));
  		break;
  
  	case OVS_KEY_ATTR_UDP:
  		err = set_udp(skb, flow_key, nla_data(a),
  			      get_mask(a, struct ovs_key_udp *));
  		break;
  
  	case OVS_KEY_ATTR_SCTP:
  		err = set_sctp(skb, flow_key, nla_data(a),
  			       get_mask(a, struct ovs_key_sctp *));
  		break;
  
  	case OVS_KEY_ATTR_MPLS:
  		err = set_mpls(skb, flow_key, nla_data(a), get_mask(a,
  								    __be32 *));
  		break;
  
  	case OVS_KEY_ATTR_CT_STATE:
  	case OVS_KEY_ATTR_CT_ZONE:
  	case OVS_KEY_ATTR_CT_MARK:
  	case OVS_KEY_ATTR_CT_LABELS:
  	case OVS_KEY_ATTR_CT_ORIG_TUPLE_IPV4:
  	case OVS_KEY_ATTR_CT_ORIG_TUPLE_IPV6:
  		err = -EINVAL;
  		break;
  	}
  
  	return err;
  }
  
  static int execute_recirc(struct datapath *dp, struct sk_buff *skb,
  			  struct sw_flow_key *key,
  			  const struct nlattr *a, int rem)
  {
  	struct deferred_action *da;
  	int level;
  
  	if (!is_flow_key_valid(key)) {
  		int err;
  
  		err = ovs_flow_key_update(skb, key);
  		if (err)
  			return err;
  	}
  	BUG_ON(!is_flow_key_valid(key));
  
  	if (!nla_is_last(a, rem)) {
  		/* Recirc action is the not the last action
  		 * of the action list, need to clone the skb.
  		 */
  		skb = skb_clone(skb, GFP_ATOMIC);
  
  		/* Skip the recirc action when out of memory, but
  		 * continue on with the rest of the action list.
  		 */
  		if (!skb)
  			return 0;
  	}
  
  	level = this_cpu_read(exec_actions_level);
  	if (level <= OVS_DEFERRED_ACTION_THRESHOLD) {
  		struct recirc_keys *rks = this_cpu_ptr(recirc_keys);
  		struct sw_flow_key *recirc_key = &rks->key[level - 1];
  
  		*recirc_key = *key;
  		recirc_key->recirc_id = nla_get_u32(a);
  		ovs_dp_process_packet(skb, recirc_key);
  
  		return 0;
  	}
  
  	da = add_deferred_actions(skb, key, NULL);
  	if (da) {
  		da->pkt_key.recirc_id = nla_get_u32(a);
  	} else {
  		kfree_skb(skb);
  
  		if (net_ratelimit())
  			pr_warn("%s: deferred action limit reached, drop recirc action\n",
  				ovs_dp_name(dp));
  	}
  
  	return 0;
  }
  
  /* Execute a list of actions against 'skb'. */
  static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
  			      struct sw_flow_key *key,
  			      const struct nlattr *attr, int len)
  {
  	const struct nlattr *a;
  	int rem;
  
  	for (a = attr, rem = len; rem > 0;
  	     a = nla_next(a, &rem)) {
  		int err = 0;
  
  		switch (nla_type(a)) {
  		case OVS_ACTION_ATTR_OUTPUT: {
  			int port = nla_get_u32(a);
  			struct sk_buff *clone;
  
  			/* Every output action needs a separate clone
  			 * of 'skb', In case the output action is the
  			 * last action, cloning can be avoided.
  			 */
  			if (nla_is_last(a, rem)) {
  				do_output(dp, skb, port, key);
  				/* 'skb' has been used for output.
  				 */
  				return 0;
  			}
  
  			clone = skb_clone(skb, GFP_ATOMIC);
  			if (clone)
  				do_output(dp, clone, port, key);
  			OVS_CB(skb)->cutlen = 0;
  			break;
  		}
  
  		case OVS_ACTION_ATTR_TRUNC: {
  			struct ovs_action_trunc *trunc = nla_data(a);
  
  			if (skb->len > trunc->max_len)
  				OVS_CB(skb)->cutlen = skb->len - trunc->max_len;
  			break;
  		}
  
  		case OVS_ACTION_ATTR_USERSPACE:
  			output_userspace(dp, skb, key, a, attr,
  						     len, OVS_CB(skb)->cutlen);
  			OVS_CB(skb)->cutlen = 0;
  			break;
  
  		case OVS_ACTION_ATTR_HASH:
  			execute_hash(skb, key, a);
  			break;
  
  		case OVS_ACTION_ATTR_PUSH_MPLS:
  			err = push_mpls(skb, key, nla_data(a));
  			break;
  
  		case OVS_ACTION_ATTR_POP_MPLS:
  			err = pop_mpls(skb, key, nla_get_be16(a));
  			break;
  
  		case OVS_ACTION_ATTR_PUSH_VLAN:
  			err = push_vlan(skb, key, nla_data(a));
  			break;
  
  		case OVS_ACTION_ATTR_POP_VLAN:
  			err = pop_vlan(skb, key);
  			break;
  
  		case OVS_ACTION_ATTR_RECIRC:
  			err = execute_recirc(dp, skb, key, a, rem);
  			if (nla_is_last(a, rem)) {
  				/* If this is the last action, the skb has
  				 * been consumed or freed.
  				 * Return immediately.
  				 */
  				return err;
  			}
  			break;
  
  		case OVS_ACTION_ATTR_SET:
  			err = execute_set_action(skb, key, nla_data(a));
  			break;
  
  		case OVS_ACTION_ATTR_SET_MASKED:
  		case OVS_ACTION_ATTR_SET_TO_MASKED:
  			err = execute_masked_set_action(skb, key, nla_data(a));
  			break;
  
  		case OVS_ACTION_ATTR_SAMPLE:
  			err = sample(dp, skb, key, a, attr, len);
  			break;
  
  		case OVS_ACTION_ATTR_CT:
  			if (!is_flow_key_valid(key)) {
  				err = ovs_flow_key_update(skb, key);
  				if (err)
  					return err;
  			}
  
  			err = ovs_ct_execute(ovs_dp_get_net(dp), skb, key,
  					     nla_data(a));
  
  			/* Hide stolen IP fragments from user space. */
  			if (err)
  				return err == -EINPROGRESS ? 0 : err;
  			break;
  
  		case OVS_ACTION_ATTR_PUSH_ETH:
  			err = push_eth(skb, key, nla_data(a));
  			break;
  
  		case OVS_ACTION_ATTR_POP_ETH:
  			err = pop_eth(skb, key);
  			break;
  		}
  
  		if (unlikely(err)) {
  			kfree_skb(skb);
  			return err;
  		}
  	}
  
  	consume_skb(skb);
  	return 0;
  }
  
  static void process_deferred_actions(struct datapath *dp)
  {
  	struct action_fifo *fifo = this_cpu_ptr(action_fifos);
  
  	/* Do not touch the FIFO in case there is no deferred actions. */
  	if (action_fifo_is_empty(fifo))
  		return;
  
  	/* Finishing executing all deferred actions. */
  	do {
  		struct deferred_action *da = action_fifo_get(fifo);
  		struct sk_buff *skb = da->skb;
  		struct sw_flow_key *key = &da->pkt_key;
  		const struct nlattr *actions = da->actions;
  
  		if (actions)
  			do_execute_actions(dp, skb, key, actions,
  					   nla_len(actions));
  		else
  			ovs_dp_process_packet(skb, key);
  	} while (!action_fifo_is_empty(fifo));
  
  	/* Reset FIFO for the next packet.  */
  	action_fifo_init(fifo);
  }
  
  /* Execute a list of actions against 'skb'. */
  int ovs_execute_actions(struct datapath *dp, struct sk_buff *skb,
  			const struct sw_flow_actions *acts,
  			struct sw_flow_key *key)
  {
  	int err, level;
  
  	level = __this_cpu_inc_return(exec_actions_level);
  	if (unlikely(level > OVS_RECURSION_LIMIT)) {
  		net_crit_ratelimited("ovs: recursion limit reached on datapath %s, probable configuration error\n",
  				     ovs_dp_name(dp));
  		kfree_skb(skb);
  		err = -ENETDOWN;
  		goto out;
  	}
  
  	err = do_execute_actions(dp, skb, key,
  				 acts->actions, acts->actions_len);
  
  	if (level == 1)
  		process_deferred_actions(dp);
  
  out:
  	__this_cpu_dec(exec_actions_level);
  	return err;
  }
  
  int action_fifos_init(void)
  {
  	action_fifos = alloc_percpu(struct action_fifo);
  	if (!action_fifos)
  		return -ENOMEM;
  
  	recirc_keys = alloc_percpu(struct recirc_keys);
  	if (!recirc_keys) {
  		free_percpu(action_fifos);
  		return -ENOMEM;
  	}
  
  	return 0;
  }
  
  void action_fifos_exit(void)
  {
  	free_percpu(action_fifos);
  	free_percpu(recirc_keys);
  }
  