/*
   * Copyright (c) 2013 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/types.h>
  #include <linux/kernel.h>
  #include <linux/skbuff.h>
  #include <linux/netdevice.h>
  #include <linux/in.h>
  #include <linux/if_arp.h>

  #include <linux/init.h>
  #include <linux/in6.h>
  #include <linux/inetdevice.h>
  #include <linux/netfilter_ipv4.h>
  #include <linux/etherdevice.h>
  #include <linux/if_ether.h>
  #include <linux/if_vlan.h>

  #include <linux/static_key.h>

  
  #include <net/ip.h>
  #include <net/icmp.h>
  #include <net/protocol.h>
  #include <net/ip_tunnels.h>

  #include <net/ip6_tunnel.h>

  #include <net/arp.h>
  #include <net/checksum.h>
  #include <net/dsfield.h>
  #include <net/inet_ecn.h>
  #include <net/xfrm.h>
  #include <net/net_namespace.h>
  #include <net/netns/generic.h>
  #include <net/rtnetlink.h>

  #include <net/dst_metadata.h>

  const struct ip_tunnel_encap_ops __rcu *
  		iptun_encaps[MAX_IPTUN_ENCAP_OPS] __read_mostly;
  EXPORT_SYMBOL(iptun_encaps);

  const struct ip6_tnl_encap_ops __rcu *
  		ip6tun_encaps[MAX_IPTUN_ENCAP_OPS] __read_mostly;
  EXPORT_SYMBOL(ip6tun_encaps);

  void iptunnel_xmit(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
  		   __be32 src, __be32 dst, __u8 proto,
  		   __u8 tos, __u8 ttl, __be16 df, bool xnet)

  {

  	int pkt_len = skb->len - skb_inner_network_offset(skb);

  	struct net *net = dev_net(rt->dst.dev);

  	struct net_device *dev = skb->dev;

  	struct iphdr *iph;
  	int err;

  	skb_scrub_packet(skb, xnet);

  	skb_clear_hash_if_not_l4(skb);

  	skb_dst_set(skb, &rt->dst);
  	memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
  
  	/* Push down and install the IP header. */

  	skb_push(skb, sizeof(struct iphdr));

  	skb_reset_network_header(skb);
  
  	iph = ip_hdr(skb);
  
  	iph->version	=	4;
  	iph->ihl	=	sizeof(struct iphdr) >> 2;
  	iph->frag_off	=	df;
  	iph->protocol	=	proto;
  	iph->tos	=	tos;
  	iph->daddr	=	dst;
  	iph->saddr	=	src;
  	iph->ttl	=	ttl;

  	__ip_select_ident(net, iph, skb_shinfo(skb)->gso_segs ?: 1);

  	err = ip_local_out(net, sk, skb);

  	if (unlikely(net_xmit_eval(err)))
  		pkt_len = 0;

  	iptunnel_xmit_stats(dev, pkt_len);

  }
  EXPORT_SYMBOL_GPL(iptunnel_xmit);

  int __iptunnel_pull_header(struct sk_buff *skb, int hdr_len,
  			   __be16 inner_proto, bool raw_proto, bool xnet)

  {
  	if (unlikely(!pskb_may_pull(skb, hdr_len)))
  		return -ENOMEM;
  
  	skb_pull_rcsum(skb, hdr_len);

  	if (!raw_proto && inner_proto == htons(ETH_P_TEB)) {

  		struct ethhdr *eh;

  
  		if (unlikely(!pskb_may_pull(skb, ETH_HLEN)))
  			return -ENOMEM;

  		eh = (struct ethhdr *)skb->data;

  		if (likely(eth_proto_is_802_3(eh->h_proto)))

  			skb->protocol = eh->h_proto;
  		else
  			skb->protocol = htons(ETH_P_802_2);
  
  	} else {
  		skb->protocol = inner_proto;
  	}

  	skb_clear_hash_if_not_l4(skb);

  	skb->vlan_tci = 0;
  	skb_set_queue_mapping(skb, 0);

  	skb_scrub_packet(skb, xnet);

  
  	return iptunnel_pull_offloads(skb);

  }

  EXPORT_SYMBOL_GPL(__iptunnel_pull_header);

  struct metadata_dst *iptunnel_metadata_reply(struct metadata_dst *md,
  					     gfp_t flags)
  {
  	struct metadata_dst *res;
  	struct ip_tunnel_info *dst, *src;
  
  	if (!md || md->u.tun_info.mode & IP_TUNNEL_INFO_TX)
  		return NULL;
  
  	res = metadata_dst_alloc(0, flags);
  	if (!res)
  		return NULL;
  
  	dst = &res->u.tun_info;
  	src = &md->u.tun_info;
  	dst->key.tun_id = src->key.tun_id;
  	if (src->mode & IP_TUNNEL_INFO_IPV6)
  		memcpy(&dst->key.u.ipv6.dst, &src->key.u.ipv6.src,
  		       sizeof(struct in6_addr));
  	else
  		dst->key.u.ipv4.dst = src->key.u.ipv4.src;
  	dst->mode = src->mode | IP_TUNNEL_INFO_TX;
  
  	return res;
  }
  EXPORT_SYMBOL_GPL(iptunnel_metadata_reply);

  int iptunnel_handle_offloads(struct sk_buff *skb,
  			     int gso_type_mask)

  {
  	int err;
  
  	if (likely(!skb->encapsulation)) {
  		skb_reset_inner_headers(skb);
  		skb->encapsulation = 1;
  	}
  
  	if (skb_is_gso(skb)) {

  		err = skb_header_unclone(skb, GFP_ATOMIC);

  		if (unlikely(err))

  			return err;

  		skb_shinfo(skb)->gso_type |= gso_type_mask;

  		return 0;

  	}

  	if (skb->ip_summed != CHECKSUM_PARTIAL) {

  		skb->ip_summed = CHECKSUM_NONE;

  		/* We clear encapsulation here to prevent badly-written
  		 * drivers potentially deciding to offload an inner checksum
  		 * if we set CHECKSUM_PARTIAL on the outer header.
  		 * This should go away when the drivers are all fixed.
  		 */

  		skb->encapsulation = 0;
  	}

  	return 0;

  }
  EXPORT_SYMBOL_GPL(iptunnel_handle_offloads);

  
  /* Often modified stats are per cpu, other are shared (netdev->stats) */
  struct rtnl_link_stats64 *ip_tunnel_get_stats64(struct net_device *dev,
  						struct rtnl_link_stats64 *tot)
  {
  	int i;

  	netdev_stats_to_stats64(tot, &dev->stats);

  	for_each_possible_cpu(i) {
  		const struct pcpu_sw_netstats *tstats =
  						   per_cpu_ptr(dev->tstats, i);
  		u64 rx_packets, rx_bytes, tx_packets, tx_bytes;
  		unsigned int start;
  
  		do {

  			start = u64_stats_fetch_begin_irq(&tstats->syncp);

  			rx_packets = tstats->rx_packets;
  			tx_packets = tstats->tx_packets;
  			rx_bytes = tstats->rx_bytes;
  			tx_bytes = tstats->tx_bytes;

  		} while (u64_stats_fetch_retry_irq(&tstats->syncp, start));

  
  		tot->rx_packets += rx_packets;
  		tot->tx_packets += tx_packets;
  		tot->rx_bytes   += rx_bytes;
  		tot->tx_bytes   += tx_bytes;
  	}

  	return tot;
  }
  EXPORT_SYMBOL_GPL(ip_tunnel_get_stats64);

  static const struct nla_policy ip_tun_policy[LWTUNNEL_IP_MAX + 1] = {
  	[LWTUNNEL_IP_ID]	= { .type = NLA_U64 },
  	[LWTUNNEL_IP_DST]	= { .type = NLA_U32 },
  	[LWTUNNEL_IP_SRC]	= { .type = NLA_U32 },
  	[LWTUNNEL_IP_TTL]	= { .type = NLA_U8 },
  	[LWTUNNEL_IP_TOS]	= { .type = NLA_U8 },

  	[LWTUNNEL_IP_FLAGS]	= { .type = NLA_U16 },

  };
  
  static int ip_tun_build_state(struct net_device *dev, struct nlattr *attr,

  			      unsigned int family, const void *cfg,

  			      struct lwtunnel_state **ts)
  {
  	struct ip_tunnel_info *tun_info;
  	struct lwtunnel_state *new_state;

  	struct nlattr *tb[LWTUNNEL_IP_MAX + 1];

  	int err;

  	err = nla_parse_nested(tb, LWTUNNEL_IP_MAX, attr, ip_tun_policy);

  	if (err < 0)
  		return err;
  
  	new_state = lwtunnel_state_alloc(sizeof(*tun_info));
  	if (!new_state)
  		return -ENOMEM;
  
  	new_state->type = LWTUNNEL_ENCAP_IP;
  
  	tun_info = lwt_tun_info(new_state);

  	if (tb[LWTUNNEL_IP_ID])

  		tun_info->key.tun_id = nla_get_be64(tb[LWTUNNEL_IP_ID]);

  	if (tb[LWTUNNEL_IP_DST])

  		tun_info->key.u.ipv4.dst = nla_get_in_addr(tb[LWTUNNEL_IP_DST]);

  	if (tb[LWTUNNEL_IP_SRC])

  		tun_info->key.u.ipv4.src = nla_get_in_addr(tb[LWTUNNEL_IP_SRC]);

  	if (tb[LWTUNNEL_IP_TTL])

  		tun_info->key.ttl = nla_get_u8(tb[LWTUNNEL_IP_TTL]);

  	if (tb[LWTUNNEL_IP_TOS])

  		tun_info->key.tos = nla_get_u8(tb[LWTUNNEL_IP_TOS]);

  	if (tb[LWTUNNEL_IP_FLAGS])

  		tun_info->key.tun_flags = nla_get_be16(tb[LWTUNNEL_IP_FLAGS]);

  
  	tun_info->mode = IP_TUNNEL_INFO_TX;

  	tun_info->options_len = 0;
  
  	*ts = new_state;
  
  	return 0;
  }
  
  static int ip_tun_fill_encap_info(struct sk_buff *skb,
  				  struct lwtunnel_state *lwtstate)
  {
  	struct ip_tunnel_info *tun_info = lwt_tun_info(lwtstate);

  	if (nla_put_be64(skb, LWTUNNEL_IP_ID, tun_info->key.tun_id,
  			 LWTUNNEL_IP_PAD) ||

  	    nla_put_in_addr(skb, LWTUNNEL_IP_DST, tun_info->key.u.ipv4.dst) ||
  	    nla_put_in_addr(skb, LWTUNNEL_IP_SRC, tun_info->key.u.ipv4.src) ||

  	    nla_put_u8(skb, LWTUNNEL_IP_TOS, tun_info->key.tos) ||
  	    nla_put_u8(skb, LWTUNNEL_IP_TTL, tun_info->key.ttl) ||

  	    nla_put_be16(skb, LWTUNNEL_IP_FLAGS, tun_info->key.tun_flags))

  		return -ENOMEM;
  
  	return 0;
  }
  
  static int ip_tun_encap_nlsize(struct lwtunnel_state *lwtstate)
  {

  	return nla_total_size_64bit(8)	/* LWTUNNEL_IP_ID */

  		+ nla_total_size(4)	/* LWTUNNEL_IP_DST */
  		+ nla_total_size(4)	/* LWTUNNEL_IP_SRC */
  		+ nla_total_size(1)	/* LWTUNNEL_IP_TOS */
  		+ nla_total_size(1)	/* LWTUNNEL_IP_TTL */

  		+ nla_total_size(2);	/* LWTUNNEL_IP_FLAGS */

  }

  static int ip_tun_cmp_encap(struct lwtunnel_state *a, struct lwtunnel_state *b)
  {
  	return memcmp(lwt_tun_info(a), lwt_tun_info(b),
  		      sizeof(struct ip_tunnel_info));
  }

  static const struct lwtunnel_encap_ops ip_tun_lwt_ops = {
  	.build_state = ip_tun_build_state,
  	.fill_encap = ip_tun_fill_encap_info,
  	.get_encap_size = ip_tun_encap_nlsize,

  	.cmp_encap = ip_tun_cmp_encap,

  	.owner = THIS_MODULE,

  };

  static const struct nla_policy ip6_tun_policy[LWTUNNEL_IP6_MAX + 1] = {
  	[LWTUNNEL_IP6_ID]		= { .type = NLA_U64 },
  	[LWTUNNEL_IP6_DST]		= { .len = sizeof(struct in6_addr) },
  	[LWTUNNEL_IP6_SRC]		= { .len = sizeof(struct in6_addr) },
  	[LWTUNNEL_IP6_HOPLIMIT]		= { .type = NLA_U8 },
  	[LWTUNNEL_IP6_TC]		= { .type = NLA_U8 },

  	[LWTUNNEL_IP6_FLAGS]		= { .type = NLA_U16 },
  };
  
  static int ip6_tun_build_state(struct net_device *dev, struct nlattr *attr,

  			       unsigned int family, const void *cfg,

  			       struct lwtunnel_state **ts)
  {
  	struct ip_tunnel_info *tun_info;
  	struct lwtunnel_state *new_state;
  	struct nlattr *tb[LWTUNNEL_IP6_MAX + 1];
  	int err;
  
  	err = nla_parse_nested(tb, LWTUNNEL_IP6_MAX, attr, ip6_tun_policy);
  	if (err < 0)
  		return err;
  
  	new_state = lwtunnel_state_alloc(sizeof(*tun_info));
  	if (!new_state)
  		return -ENOMEM;
  
  	new_state->type = LWTUNNEL_ENCAP_IP6;
  
  	tun_info = lwt_tun_info(new_state);
  
  	if (tb[LWTUNNEL_IP6_ID])

  		tun_info->key.tun_id = nla_get_be64(tb[LWTUNNEL_IP6_ID]);

  
  	if (tb[LWTUNNEL_IP6_DST])
  		tun_info->key.u.ipv6.dst = nla_get_in6_addr(tb[LWTUNNEL_IP6_DST]);
  
  	if (tb[LWTUNNEL_IP6_SRC])
  		tun_info->key.u.ipv6.src = nla_get_in6_addr(tb[LWTUNNEL_IP6_SRC]);
  
  	if (tb[LWTUNNEL_IP6_HOPLIMIT])
  		tun_info->key.ttl = nla_get_u8(tb[LWTUNNEL_IP6_HOPLIMIT]);
  
  	if (tb[LWTUNNEL_IP6_TC])
  		tun_info->key.tos = nla_get_u8(tb[LWTUNNEL_IP6_TC]);

  	if (tb[LWTUNNEL_IP6_FLAGS])

  		tun_info->key.tun_flags = nla_get_be16(tb[LWTUNNEL_IP6_FLAGS]);

  	tun_info->mode = IP_TUNNEL_INFO_TX | IP_TUNNEL_INFO_IPV6;

  	tun_info->options_len = 0;
  
  	*ts = new_state;
  
  	return 0;
  }
  
  static int ip6_tun_fill_encap_info(struct sk_buff *skb,
  				   struct lwtunnel_state *lwtstate)
  {
  	struct ip_tunnel_info *tun_info = lwt_tun_info(lwtstate);

  	if (nla_put_be64(skb, LWTUNNEL_IP6_ID, tun_info->key.tun_id,
  			 LWTUNNEL_IP6_PAD) ||

  	    nla_put_in6_addr(skb, LWTUNNEL_IP6_DST, &tun_info->key.u.ipv6.dst) ||
  	    nla_put_in6_addr(skb, LWTUNNEL_IP6_SRC, &tun_info->key.u.ipv6.src) ||

  	    nla_put_u8(skb, LWTUNNEL_IP6_TC, tun_info->key.tos) ||
  	    nla_put_u8(skb, LWTUNNEL_IP6_HOPLIMIT, tun_info->key.ttl) ||

  	    nla_put_be16(skb, LWTUNNEL_IP6_FLAGS, tun_info->key.tun_flags))

  		return -ENOMEM;
  
  	return 0;
  }
  
  static int ip6_tun_encap_nlsize(struct lwtunnel_state *lwtstate)
  {

  	return nla_total_size_64bit(8)	/* LWTUNNEL_IP6_ID */

  		+ nla_total_size(16)	/* LWTUNNEL_IP6_DST */
  		+ nla_total_size(16)	/* LWTUNNEL_IP6_SRC */
  		+ nla_total_size(1)	/* LWTUNNEL_IP6_HOPLIMIT */
  		+ nla_total_size(1)	/* LWTUNNEL_IP6_TC */

  		+ nla_total_size(2);	/* LWTUNNEL_IP6_FLAGS */
  }
  
  static const struct lwtunnel_encap_ops ip6_tun_lwt_ops = {
  	.build_state = ip6_tun_build_state,
  	.fill_encap = ip6_tun_fill_encap_info,
  	.get_encap_size = ip6_tun_encap_nlsize,
  	.cmp_encap = ip_tun_cmp_encap,

  	.owner = THIS_MODULE,

  };

  void __init ip_tunnel_core_init(void)

  {

  	/* If you land here, make sure whether increasing ip_tunnel_info's
  	 * options_len is a reasonable choice with its usage in front ends
  	 * (f.e., it's part of flow keys, etc).
  	 */
  	BUILD_BUG_ON(IP_TUNNEL_OPTS_MAX != 255);

  	lwtunnel_encap_add_ops(&ip_tun_lwt_ops, LWTUNNEL_ENCAP_IP);

  	lwtunnel_encap_add_ops(&ip6_tun_lwt_ops, LWTUNNEL_ENCAP_IP6);

  }

  
  struct static_key ip_tunnel_metadata_cnt = STATIC_KEY_INIT_FALSE;
  EXPORT_SYMBOL(ip_tunnel_metadata_cnt);
  
  void ip_tunnel_need_metadata(void)
  {
  	static_key_slow_inc(&ip_tunnel_metadata_cnt);
  }
  EXPORT_SYMBOL_GPL(ip_tunnel_need_metadata);
  
  void ip_tunnel_unneed_metadata(void)
  {
  	static_key_slow_dec(&ip_tunnel_metadata_cnt);
  }
  EXPORT_SYMBOL_GPL(ip_tunnel_unneed_metadata);