// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   * INET		An implementation of the TCP/IP protocol suite for the LINUX
   *		operating system.  INET is implemented using the  BSD Socket
   *		interface as the means of communication with the user level.
   *
   *		IPv4 Forwarding Information Base: FIB frontend.
   *

   * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>

   */

  #include <linux/module.h>

  #include <linux/uaccess.h>

  #include <linux/bitops.h>

  #include <linux/capability.h>

  #include <linux/types.h>
  #include <linux/kernel.h>

  #include <linux/mm.h>
  #include <linux/string.h>
  #include <linux/socket.h>
  #include <linux/sockios.h>
  #include <linux/errno.h>
  #include <linux/in.h>
  #include <linux/inet.h>

  #include <linux/inetdevice.h>

  #include <linux/netdevice.h>

  #include <linux/if_addr.h>

  #include <linux/if_arp.h>
  #include <linux/skbuff.h>

  #include <linux/cache.h>

  #include <linux/init.h>

  #include <linux/list.h>

  #include <linux/slab.h>

  
  #include <net/ip.h>
  #include <net/protocol.h>
  #include <net/route.h>
  #include <net/tcp.h>
  #include <net/sock.h>

  #include <net/arp.h>
  #include <net/ip_fib.h>

  #include <net/nexthop.h>

  #include <net/rtnetlink.h>

  #include <net/xfrm.h>

  #include <net/l3mdev.h>

  #include <net/lwtunnel.h>

  #include <trace/events/fib.h>

  #ifndef CONFIG_IP_MULTIPLE_TABLES

  static int __net_init fib4_rules_init(struct net *net)

  {

  	struct fib_table *local_table, *main_table;

  	main_table  = fib_trie_table(RT_TABLE_MAIN, NULL);

  	if (!main_table)

  		return -ENOMEM;

  	local_table = fib_trie_table(RT_TABLE_LOCAL, main_table);

  	if (!local_table)

  		goto fail;

  	hlist_add_head_rcu(&local_table->tb_hlist,

  				&net->ipv4.fib_table_hash[TABLE_LOCAL_INDEX]);

  	hlist_add_head_rcu(&main_table->tb_hlist,

  				&net->ipv4.fib_table_hash[TABLE_MAIN_INDEX]);

  	return 0;
  
  fail:

  	fib_free_table(main_table);

  	return -ENOMEM;

  }

  
  static bool fib4_has_custom_rules(struct net *net)
  {
  	return false;
  }

  #else

  struct fib_table *fib_new_table(struct net *net, u32 id)

  {

  	struct fib_table *tb, *alias = NULL;

  	unsigned int h;

  	if (id == 0)
  		id = RT_TABLE_MAIN;

  	tb = fib_get_table(net, id);

  	if (tb)
  		return tb;

  	if (id == RT_TABLE_LOCAL && !net->ipv4.fib_has_custom_rules)

  		alias = fib_new_table(net, RT_TABLE_MAIN);
  
  	tb = fib_trie_table(id, alias);

  	if (!tb)
  		return NULL;

  
  	switch (id) {

  	case RT_TABLE_MAIN:

  		rcu_assign_pointer(net->ipv4.fib_main, tb);

  		break;

  	case RT_TABLE_DEFAULT:

  		rcu_assign_pointer(net->ipv4.fib_default, tb);

  		break;

  	default:
  		break;
  	}

  	h = id & (FIB_TABLE_HASHSZ - 1);

  	hlist_add_head_rcu(&tb->tb_hlist, &net->ipv4.fib_table_hash[h]);

  	return tb;
  }

  EXPORT_SYMBOL_GPL(fib_new_table);

  /* caller must hold either rtnl or rcu read lock */

  struct fib_table *fib_get_table(struct net *net, u32 id)

  {
  	struct fib_table *tb;

  	struct hlist_head *head;

  	unsigned int h;

  	if (id == 0)
  		id = RT_TABLE_MAIN;
  	h = id & (FIB_TABLE_HASHSZ - 1);

  	head = &net->ipv4.fib_table_hash[h];

  	hlist_for_each_entry_rcu(tb, head, tb_hlist,
  				 lockdep_rtnl_is_held()) {

  		if (tb->tb_id == id)

  			return tb;

  	}

  	return NULL;
  }

  
  static bool fib4_has_custom_rules(struct net *net)
  {
  	return net->ipv4.fib_has_custom_rules;
  }

  #endif /* CONFIG_IP_MULTIPLE_TABLES */

  static void fib_replace_table(struct net *net, struct fib_table *old,
  			      struct fib_table *new)
  {
  #ifdef CONFIG_IP_MULTIPLE_TABLES
  	switch (new->tb_id) {

  	case RT_TABLE_MAIN:
  		rcu_assign_pointer(net->ipv4.fib_main, new);
  		break;
  	case RT_TABLE_DEFAULT:
  		rcu_assign_pointer(net->ipv4.fib_default, new);
  		break;
  	default:
  		break;
  	}
  
  #endif
  	/* replace the old table in the hlist */
  	hlist_replace_rcu(&old->tb_hlist, &new->tb_hlist);
  }
  
  int fib_unmerge(struct net *net)
  {

  	struct fib_table *old, *new, *main_table;

  	/* attempt to fetch local table if it has been allocated */

  	old = fib_get_table(net, RT_TABLE_LOCAL);

  	if (!old)
  		return 0;

  	new = fib_trie_unmerge(old);

  	if (!new)
  		return -ENOMEM;

  	/* table is already unmerged */
  	if (new == old)
  		return 0;

  	/* replace merged table with clean table */

  	fib_replace_table(net, old, new);
  	fib_free_table(old);
  
  	/* attempt to fetch main table if it has been allocated */
  	main_table = fib_get_table(net, RT_TABLE_MAIN);
  	if (!main_table)
  		return 0;
  
  	/* flush local entries from main table */
  	fib_table_flush_external(main_table);

  
  	return 0;
  }

  void fib_flush(struct net *net)

  {
  	int flushed = 0;

  	unsigned int h;

  	for (h = 0; h < FIB_TABLE_HASHSZ; h++) {

  		struct hlist_head *head = &net->ipv4.fib_table_hash[h];
  		struct hlist_node *tmp;
  		struct fib_table *tb;
  
  		hlist_for_each_entry_safe(tb, tmp, head, tb_hlist)

  			flushed += fib_table_flush(net, tb, false);

  	}

  
  	if (flushed)

  		rt_cache_flush(net);

  }

  /*
   * Find address type as if only "dev" was present in the system. If
   * on_dev is NULL then all interfaces are taken into consideration.
   */

  static inline unsigned int __inet_dev_addr_type(struct net *net,
  						const struct net_device *dev,

  						__be32 addr, u32 tb_id)

  {

  	struct flowi4		fl4 = { .daddr = addr };

  	struct fib_result	res;

  	unsigned int ret = RTN_BROADCAST;

  	struct fib_table *table;

  	if (ipv4_is_zeronet(addr) || ipv4_is_lbcast(addr))

  		return RTN_BROADCAST;

  	if (ipv4_is_multicast(addr))

  		return RTN_MULTICAST;

  	rcu_read_lock();

  	table = fib_get_table(net, tb_id);
  	if (table) {

  		ret = RTN_UNICAST;

  		if (!fib_table_lookup(table, &fl4, &res, FIB_LOOKUP_NOREF)) {

  			struct fib_nh_common *nhc = fib_info_nhc(res.fi, 0);

  			if (!dev || dev == nhc->nhc_dev)

  				ret = res.type;

  		}
  	}

  
  	rcu_read_unlock();

  	return ret;
  }

  unsigned int inet_addr_type_table(struct net *net, __be32 addr, u32 tb_id)

  {
  	return __inet_dev_addr_type(net, NULL, addr, tb_id);
  }
  EXPORT_SYMBOL(inet_addr_type_table);

  unsigned int inet_addr_type(struct net *net, __be32 addr)

  {

  	return __inet_dev_addr_type(net, NULL, addr, RT_TABLE_LOCAL);

  }

  EXPORT_SYMBOL(inet_addr_type);

  unsigned int inet_dev_addr_type(struct net *net, const struct net_device *dev,
  				__be32 addr)

  {

  	u32 rt_table = l3mdev_fib_table(dev) ? : RT_TABLE_LOCAL;

  
  	return __inet_dev_addr_type(net, dev, addr, rt_table);

  }

  EXPORT_SYMBOL(inet_dev_addr_type);

  /* inet_addr_type with dev == NULL but using the table from a dev
   * if one is associated
   */
  unsigned int inet_addr_type_dev_table(struct net *net,
  				      const struct net_device *dev,
  				      __be32 addr)
  {

  	u32 rt_table = l3mdev_fib_table(dev) ? : RT_TABLE_LOCAL;

  
  	return __inet_dev_addr_type(net, NULL, addr, rt_table);
  }
  EXPORT_SYMBOL(inet_addr_type_dev_table);

  __be32 fib_compute_spec_dst(struct sk_buff *skb)
  {
  	struct net_device *dev = skb->dev;
  	struct in_device *in_dev;
  	struct fib_result res;

  	struct rtable *rt;

  	struct net *net;

  	int scope;

  	rt = skb_rtable(skb);

  	if ((rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST | RTCF_LOCAL)) ==
  	    RTCF_LOCAL)

  		return ip_hdr(skb)->daddr;
  
  	in_dev = __in_dev_get_rcu(dev);

  
  	net = dev_net(dev);

  
  	scope = RT_SCOPE_UNIVERSE;
  	if (!ipv4_is_zeronet(ip_hdr(skb)->saddr)) {

  		bool vmark = in_dev && IN_DEV_SRC_VMARK(in_dev);

  		struct flowi4 fl4 = {
  			.flowi4_iif = LOOPBACK_IFINDEX,

  			.flowi4_oif = l3mdev_master_ifindex_rcu(dev),

  			.daddr = ip_hdr(skb)->saddr,
  			.flowi4_tos = RT_TOS(ip_hdr(skb)->tos),
  			.flowi4_scope = scope,

  			.flowi4_mark = vmark ? skb->mark : 0,

  		};

  		if (!fib_lookup(net, &fl4, &res, 0))

  			return fib_result_prefsrc(net, &res);

  	} else {
  		scope = RT_SCOPE_LINK;
  	}
  
  	return inet_select_addr(dev, ip_hdr(skb)->saddr, scope);

  }

  bool fib_info_nh_uses_dev(struct fib_info *fi, const struct net_device *dev)
  {
  	bool dev_match = false;

  #ifdef CONFIG_IP_ROUTE_MULTIPATH

  	int ret;

  	for (ret = 0; ret < fib_info_num_path(fi); ret++) {

  		const struct fib_nh_common *nhc = fib_info_nhc(fi, ret);

  		if (nhc->nhc_dev == dev) {

  			dev_match = true;
  			break;

  		} else if (l3mdev_master_ifindex_rcu(nhc->nhc_dev) == dev->ifindex) {

  			dev_match = true;
  			break;
  		}
  	}
  #else

  	if (fib_info_nhc(fi, 0)->nhc_dev == dev)

  		dev_match = true;
  #endif
  
  	return dev_match;
  }
  EXPORT_SYMBOL_GPL(fib_info_nh_uses_dev);

  /* Given (packet source, input interface) and optional (dst, oif, tos):

   * - (main) check, that source is valid i.e. not broadcast or our local
   *   address.
   * - figure out what "logical" interface this packet arrived
   *   and calculate "specific destination" address.
   * - check, that packet arrived from expected physical interface.

   * called with rcu_read_lock()

   */

  static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
  				 u8 tos, int oif, struct net_device *dev,
  				 int rpf, struct in_device *idev, u32 *itag)

  {

  	struct net *net = dev_net(dev);
  	struct flow_keys flkeys;

  	int ret, no_addr;

  	struct fib_result res;

  	struct flowi4 fl4;

  	bool dev_match;

  	fl4.flowi4_oif = 0;

  	fl4.flowi4_iif = l3mdev_master_ifindex_rcu(dev);

  	if (!fl4.flowi4_iif)
  		fl4.flowi4_iif = oif ? : LOOPBACK_IFINDEX;

  	fl4.daddr = src;
  	fl4.saddr = dst;
  	fl4.flowi4_tos = tos;
  	fl4.flowi4_scope = RT_SCOPE_UNIVERSE;

  	fl4.flowi4_tun_key.tun_id = 0;

  	fl4.flowi4_flags = 0;

  	fl4.flowi4_uid = sock_net_uid(net, NULL);

  	no_addr = idev->ifa_list == NULL;

  	fl4.flowi4_mark = IN_DEV_SRC_VMARK(idev) ? skb->mark : 0;

  	if (!fib4_rules_early_flow_dissect(net, skb, &fl4, &flkeys)) {
  		fl4.flowi4_proto = 0;
  		fl4.fl4_sport = 0;
  		fl4.fl4_dport = 0;
  	}

  	if (fib_lookup(net, &fl4, &res, 0))

  		goto last_resort;

  	if (res.type != RTN_UNICAST &&
  	    (res.type != RTN_LOCAL || !IN_DEV_ACCEPT_LOCAL(idev)))
  		goto e_inval;

  	fib_combine_itag(itag, &res);

  	dev_match = fib_info_nh_uses_dev(res.fi, dev);

  	/* This is not common, loopback packets retain skb_dst so normally they
  	 * would not even hit this slow path.
  	 */
  	dev_match = dev_match || (res.type == RTN_LOCAL &&
  				  dev == net->loopback_dev);

  	if (dev_match) {

  		ret = FIB_RES_NHC(res)->nhc_scope >= RT_SCOPE_HOST;

  		return ret;
  	}

  	if (no_addr)
  		goto last_resort;

  	if (rpf == 1)

  		goto e_rpf;

  	fl4.flowi4_oif = dev->ifindex;

  
  	ret = 0;

  	if (fib_lookup(net, &fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE) == 0) {

  		if (res.type == RTN_UNICAST)

  			ret = FIB_RES_NHC(res)->nhc_scope >= RT_SCOPE_HOST;

  	}
  	return ret;
  
  last_resort:
  	if (rpf)

  		goto e_rpf;

  	*itag = 0;
  	return 0;

  e_inval:
  	return -EINVAL;

  e_rpf:
  	return -EXDEV;

  }

  /* Ignore rp_filter for packets protected by IPsec. */
  int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
  			u8 tos, int oif, struct net_device *dev,
  			struct in_device *idev, u32 *itag)
  {
  	int r = secpath_exists(skb) ? 0 : IN_DEV_RPFILTER(idev);

  	struct net *net = dev_net(dev);

  	if (!r && !fib_num_tclassid_users(net) &&

  	    (dev->ifindex != oif || !IN_DEV_TX_REDIRECTS(idev))) {

  		if (IN_DEV_ACCEPT_LOCAL(idev))
  			goto ok;

  		/* with custom local routes in place, checking local addresses
  		 * only will be too optimistic, with custom rules, checking
  		 * local addresses only can be too strict, e.g. due to vrf

  		 */

  		if (net->ipv4.fib_has_custom_local_routes ||
  		    fib4_has_custom_rules(net))

  			goto full_check;
  		if (inet_lookup_ifaddr_rcu(net, src))
  			return -EINVAL;
  
  ok:

  		*itag = 0;
  		return 0;
  	}

  
  full_check:

  	return __fib_validate_source(skb, src, dst, tos, oif, dev, r, idev, itag);
  }

  static inline __be32 sk_extract_addr(struct sockaddr *addr)

  {
  	return ((struct sockaddr_in *) addr)->sin_addr.s_addr;
  }
  
  static int put_rtax(struct nlattr *mx, int len, int type, u32 value)
  {
  	struct nlattr *nla;
  
  	nla = (struct nlattr *) ((char *) mx + len);
  	nla->nla_type = type;
  	nla->nla_len = nla_attr_size(4);
  	*(u32 *) nla_data(nla) = value;
  
  	return len + nla_total_size(4);
  }

  static int rtentry_to_fib_config(struct net *net, int cmd, struct rtentry *rt,

  				 struct fib_config *cfg)
  {

  	__be32 addr;

  	int plen;
  
  	memset(cfg, 0, sizeof(*cfg));

  	cfg->fc_nlinfo.nl_net = net;

  
  	if (rt->rt_dst.sa_family != AF_INET)
  		return -EAFNOSUPPORT;
  
  	/*
  	 * Check mask for validity:
  	 * a) it must be contiguous.
  	 * b) destination must have all host bits clear.
  	 * c) if application forgot to set correct family (AF_INET),
  	 *    reject request unless it is absolutely clear i.e.
  	 *    both family and mask are zero.
  	 */
  	plen = 32;
  	addr = sk_extract_addr(&rt->rt_dst);
  	if (!(rt->rt_flags & RTF_HOST)) {

  		__be32 mask = sk_extract_addr(&rt->rt_genmask);

  
  		if (rt->rt_genmask.sa_family != AF_INET) {
  			if (mask || rt->rt_genmask.sa_family)
  				return -EAFNOSUPPORT;
  		}
  
  		if (bad_mask(mask, addr))
  			return -EINVAL;
  
  		plen = inet_mask_len(mask);
  	}
  
  	cfg->fc_dst_len = plen;
  	cfg->fc_dst = addr;
  
  	if (cmd != SIOCDELRT) {
  		cfg->fc_nlflags = NLM_F_CREATE;
  		cfg->fc_protocol = RTPROT_BOOT;
  	}
  
  	if (rt->rt_metric)
  		cfg->fc_priority = rt->rt_metric - 1;
  
  	if (rt->rt_flags & RTF_REJECT) {
  		cfg->fc_scope = RT_SCOPE_HOST;
  		cfg->fc_type = RTN_UNREACHABLE;
  		return 0;
  	}
  
  	cfg->fc_scope = RT_SCOPE_NOWHERE;
  	cfg->fc_type = RTN_UNICAST;
  
  	if (rt->rt_dev) {
  		char *colon;
  		struct net_device *dev;
  		char devname[IFNAMSIZ];
  
  		if (copy_from_user(devname, rt->rt_dev, IFNAMSIZ-1))
  			return -EFAULT;
  
  		devname[IFNAMSIZ-1] = 0;
  		colon = strchr(devname, ':');
  		if (colon)
  			*colon = 0;

  		dev = __dev_get_by_name(net, devname);

  		if (!dev)
  			return -ENODEV;
  		cfg->fc_oif = dev->ifindex;

  		cfg->fc_table = l3mdev_fib_table(dev);

  		if (colon) {

  			const struct in_ifaddr *ifa;
  			struct in_device *in_dev;
  
  			in_dev = __in_dev_get_rtnl(dev);

  			if (!in_dev)
  				return -ENODEV;

  			*colon = ':';

  
  			rcu_read_lock();
  			in_dev_for_each_ifa_rcu(ifa, in_dev) {

  				if (strcmp(ifa->ifa_label, devname) == 0)
  					break;

  			}
  			rcu_read_unlock();

  			if (!ifa)

  				return -ENODEV;
  			cfg->fc_prefsrc = ifa->ifa_local;
  		}
  	}
  
  	addr = sk_extract_addr(&rt->rt_gateway);
  	if (rt->rt_gateway.sa_family == AF_INET && addr) {

  		unsigned int addr_type;

  		cfg->fc_gw4 = addr;
  		cfg->fc_gw_family = AF_INET;

  		addr_type = inet_addr_type_table(net, addr, cfg->fc_table);

  		if (rt->rt_flags & RTF_GATEWAY &&

  		    addr_type == RTN_UNICAST)

  			cfg->fc_scope = RT_SCOPE_UNIVERSE;
  	}
  
  	if (cmd == SIOCDELRT)
  		return 0;

  	if (rt->rt_flags & RTF_GATEWAY && !cfg->fc_gw_family)

  		return -EINVAL;
  
  	if (cfg->fc_scope == RT_SCOPE_NOWHERE)
  		cfg->fc_scope = RT_SCOPE_LINK;
  
  	if (rt->rt_flags & (RTF_MTU | RTF_WINDOW | RTF_IRTT)) {
  		struct nlattr *mx;
  		int len = 0;

  		mx = kcalloc(3, nla_total_size(4), GFP_KERNEL);

  		if (!mx)

  			return -ENOMEM;
  
  		if (rt->rt_flags & RTF_MTU)
  			len = put_rtax(mx, len, RTAX_ADVMSS, rt->rt_mtu - 40);
  
  		if (rt->rt_flags & RTF_WINDOW)
  			len = put_rtax(mx, len, RTAX_WINDOW, rt->rt_window);
  
  		if (rt->rt_flags & RTF_IRTT)
  			len = put_rtax(mx, len, RTAX_RTT, rt->rt_irtt << 3);
  
  		cfg->fc_mx = mx;
  		cfg->fc_mx_len = len;
  	}
  
  	return 0;
  }

  /*

   * Handle IP routing ioctl calls.
   * These are used to manipulate the routing tables

   */

  int ip_rt_ioctl(struct net *net, unsigned int cmd, struct rtentry *rt)

  {

  	struct fib_config cfg;

  	int err;

  
  	switch (cmd) {
  	case SIOCADDRT:		/* Add a route */
  	case SIOCDELRT:		/* Delete a route */

  		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))

  			return -EPERM;

  		rtnl_lock();

  		err = rtentry_to_fib_config(net, cmd, rt, &cfg);

  		if (err == 0) {

  			struct fib_table *tb;

  			if (cmd == SIOCDELRT) {

  				tb = fib_get_table(net, cfg.fc_table);

  				if (tb)

  					err = fib_table_delete(net, tb, &cfg,
  							       NULL);

  				else
  					err = -ESRCH;

  			} else {

  				tb = fib_new_table(net, cfg.fc_table);

  				if (tb)

  					err = fib_table_insert(net, tb,
  							       &cfg, NULL);

  				else
  					err = -ENOBUFS;

  			}

  
  			/* allocated by rtentry_to_fib_config() */
  			kfree(cfg.fc_mx);

  		}
  		rtnl_unlock();
  		return err;
  	}
  	return -EINVAL;
  }

  const struct nla_policy rtm_ipv4_policy[RTA_MAX + 1] = {

  	[RTA_UNSPEC]		= { .strict_start_type = RTA_DPORT + 1 },

  	[RTA_DST]		= { .type = NLA_U32 },
  	[RTA_SRC]		= { .type = NLA_U32 },
  	[RTA_IIF]		= { .type = NLA_U32 },
  	[RTA_OIF]		= { .type = NLA_U32 },
  	[RTA_GATEWAY]		= { .type = NLA_U32 },
  	[RTA_PRIORITY]		= { .type = NLA_U32 },
  	[RTA_PREFSRC]		= { .type = NLA_U32 },
  	[RTA_METRICS]		= { .type = NLA_NESTED },

  	[RTA_MULTIPATH]		= { .len = sizeof(struct rtnexthop) },

  	[RTA_FLOW]		= { .type = NLA_U32 },

  	[RTA_ENCAP_TYPE]	= { .type = NLA_U16 },
  	[RTA_ENCAP]		= { .type = NLA_NESTED },

  	[RTA_UID]		= { .type = NLA_U32 },

  	[RTA_MARK]		= { .type = NLA_U32 },

  	[RTA_TABLE]		= { .type = NLA_U32 },

  	[RTA_IP_PROTO]		= { .type = NLA_U8 },
  	[RTA_SPORT]		= { .type = NLA_U16 },
  	[RTA_DPORT]		= { .type = NLA_U16 },

  	[RTA_NH_ID]		= { .type = NLA_U32 },

  };

  int fib_gw_from_via(struct fib_config *cfg, struct nlattr *nla,
  		    struct netlink_ext_ack *extack)
  {
  	struct rtvia *via;
  	int alen;
  
  	if (nla_len(nla) < offsetof(struct rtvia, rtvia_addr)) {
  		NL_SET_ERR_MSG(extack, "Invalid attribute length for RTA_VIA");
  		return -EINVAL;
  	}
  
  	via = nla_data(nla);
  	alen = nla_len(nla) - offsetof(struct rtvia, rtvia_addr);
  
  	switch (via->rtvia_family) {
  	case AF_INET:
  		if (alen != sizeof(__be32)) {
  			NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_VIA");
  			return -EINVAL;
  		}
  		cfg->fc_gw_family = AF_INET;
  		cfg->fc_gw4 = *((__be32 *)via->rtvia_addr);
  		break;
  	case AF_INET6:
  #ifdef CONFIG_IPV6
  		if (alen != sizeof(struct in6_addr)) {
  			NL_SET_ERR_MSG(extack, "Invalid IPv6 address in RTA_VIA");
  			return -EINVAL;
  		}
  		cfg->fc_gw_family = AF_INET6;
  		cfg->fc_gw6 = *((struct in6_addr *)via->rtvia_addr);
  #else
  		NL_SET_ERR_MSG(extack, "IPv6 support not enabled in kernel");
  		return -EINVAL;
  #endif
  		break;
  	default:
  		NL_SET_ERR_MSG(extack, "Unsupported address family in RTA_VIA");
  		return -EINVAL;
  	}
  
  	return 0;
  }

  static int rtm_to_fib_config(struct net *net, struct sk_buff *skb,

  			     struct nlmsghdr *nlh, struct fib_config *cfg,
  			     struct netlink_ext_ack *extack)

  {

  	bool has_gw = false, has_via = false;

  	struct nlattr *attr;
  	int err, remaining;
  	struct rtmsg *rtm;

  	err = nlmsg_validate_deprecated(nlh, sizeof(*rtm), RTA_MAX,
  					rtm_ipv4_policy, extack);

  	if (err < 0)
  		goto errout;
  
  	memset(cfg, 0, sizeof(*cfg));
  
  	rtm = nlmsg_data(nlh);

  	cfg->fc_dst_len = rtm->rtm_dst_len;

  	cfg->fc_tos = rtm->rtm_tos;
  	cfg->fc_table = rtm->rtm_table;
  	cfg->fc_protocol = rtm->rtm_protocol;
  	cfg->fc_scope = rtm->rtm_scope;
  	cfg->fc_type = rtm->rtm_type;
  	cfg->fc_flags = rtm->rtm_flags;
  	cfg->fc_nlflags = nlh->nlmsg_flags;

  	cfg->fc_nlinfo.portid = NETLINK_CB(skb).portid;

  	cfg->fc_nlinfo.nlh = nlh;

  	cfg->fc_nlinfo.nl_net = net;

  	if (cfg->fc_type > RTN_MAX) {

  		NL_SET_ERR_MSG(extack, "Invalid route type");

  		err = -EINVAL;
  		goto errout;
  	}

  	nlmsg_for_each_attr(attr, nlh, sizeof(struct rtmsg), remaining) {

  		switch (nla_type(attr)) {

  		case RTA_DST:

  			cfg->fc_dst = nla_get_be32(attr);

  			break;

  		case RTA_OIF:
  			cfg->fc_oif = nla_get_u32(attr);
  			break;
  		case RTA_GATEWAY:

  			has_gw = true;

  			cfg->fc_gw4 = nla_get_be32(attr);

  			if (cfg->fc_gw4)
  				cfg->fc_gw_family = AF_INET;

  			break;

  		case RTA_VIA:

  			has_via = true;
  			err = fib_gw_from_via(cfg, attr, extack);
  			if (err)
  				goto errout;
  			break;

  		case RTA_PRIORITY:
  			cfg->fc_priority = nla_get_u32(attr);
  			break;
  		case RTA_PREFSRC:

  			cfg->fc_prefsrc = nla_get_be32(attr);

  			break;
  		case RTA_METRICS:
  			cfg->fc_mx = nla_data(attr);
  			cfg->fc_mx_len = nla_len(attr);
  			break;
  		case RTA_MULTIPATH:

  			err = lwtunnel_valid_encap_type_attr(nla_data(attr),

  							     nla_len(attr),
  							     extack);

  			if (err < 0)
  				goto errout;

  			cfg->fc_mp = nla_data(attr);
  			cfg->fc_mp_len = nla_len(attr);
  			break;
  		case RTA_FLOW:
  			cfg->fc_flow = nla_get_u32(attr);
  			break;

  		case RTA_TABLE:
  			cfg->fc_table = nla_get_u32(attr);
  			break;

  		case RTA_ENCAP:
  			cfg->fc_encap = attr;
  			break;
  		case RTA_ENCAP_TYPE:
  			cfg->fc_encap_type = nla_get_u16(attr);

  			err = lwtunnel_valid_encap_type(cfg->fc_encap_type,
  							extack);

  			if (err < 0)
  				goto errout;

  			break;

  		case RTA_NH_ID:
  			cfg->fc_nh_id = nla_get_u32(attr);
  			break;
  		}
  	}
  
  	if (cfg->fc_nh_id) {
  		if (cfg->fc_oif || cfg->fc_gw_family ||
  		    cfg->fc_encap || cfg->fc_mp) {
  			NL_SET_ERR_MSG(extack,
  				       "Nexthop specification and nexthop id are mutually exclusive");
  			return -EINVAL;

  		}
  	}

  	if (has_gw && has_via) {
  		NL_SET_ERR_MSG(extack,
  			       "Nexthop configuration can not contain both GATEWAY and VIA");
  		goto errout;
  	}

  	return 0;

  errout:
  	return err;

  }

  static int inet_rtm_delroute(struct sk_buff *skb, struct nlmsghdr *nlh,
  			     struct netlink_ext_ack *extack)

  {

  	struct net *net = sock_net(skb->sk);

  	struct fib_config cfg;
  	struct fib_table *tb;
  	int err;

  	err = rtm_to_fib_config(net, skb, nlh, &cfg, extack);

  	if (err < 0)
  		goto errout;

  	if (cfg.fc_nh_id && !nexthop_find_by_id(net, cfg.fc_nh_id)) {
  		NL_SET_ERR_MSG(extack, "Nexthop id does not exist");
  		err = -EINVAL;
  		goto errout;
  	}

  	tb = fib_get_table(net, cfg.fc_table);

  	if (!tb) {

  		NL_SET_ERR_MSG(extack, "FIB table does not exist");

  		err = -ESRCH;
  		goto errout;
  	}

  	err = fib_table_delete(net, tb, &cfg, extack);

  errout:
  	return err;

  }

  static int inet_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh,
  			     struct netlink_ext_ack *extack)

  {

  	struct net *net = sock_net(skb->sk);

  	struct fib_config cfg;
  	struct fib_table *tb;
  	int err;

  	err = rtm_to_fib_config(net, skb, nlh, &cfg, extack);

  	if (err < 0)
  		goto errout;

  	tb = fib_new_table(net, cfg.fc_table);

  	if (!tb) {

  		err = -ENOBUFS;
  		goto errout;
  	}

  	err = fib_table_insert(net, tb, &cfg, extack);

  	if (!err && cfg.fc_type == RTN_LOCAL)
  		net->ipv4.fib_has_custom_local_routes = true;

  errout:
  	return err;

  }

  int ip_valid_fib_dump_req(struct net *net, const struct nlmsghdr *nlh,
  			  struct fib_dump_filter *filter,

  			  struct netlink_callback *cb)

  {

  	struct netlink_ext_ack *extack = cb->extack;
  	struct nlattr *tb[RTA_MAX + 1];

  	struct rtmsg *rtm;

  	int err, i;
  
  	ASSERT_RTNL();

  
  	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
  		NL_SET_ERR_MSG(extack, "Invalid header for FIB dump request");
  		return -EINVAL;
  	}
  
  	rtm = nlmsg_data(nlh);
  	if (rtm->rtm_dst_len || rtm->rtm_src_len  || rtm->rtm_tos   ||

  	    rtm->rtm_scope) {

  		NL_SET_ERR_MSG(extack, "Invalid values in header for FIB dump request");
  		return -EINVAL;
  	}

  	if (rtm->rtm_flags & ~(RTM_F_CLONED | RTM_F_PREFIX)) {
  		NL_SET_ERR_MSG(extack, "Invalid flags for FIB dump request");
  		return -EINVAL;
  	}

  	if (rtm->rtm_flags & RTM_F_CLONED)
  		filter->dump_routes = false;
  	else
  		filter->dump_exceptions = false;

  	filter->dump_all_families = (rtm->rtm_family == AF_UNSPEC);

  	filter->flags    = rtm->rtm_flags;
  	filter->protocol = rtm->rtm_protocol;
  	filter->rt_type  = rtm->rtm_type;
  	filter->table_id = rtm->rtm_table;

  	err = nlmsg_parse_deprecated_strict(nlh, sizeof(*rtm), tb, RTA_MAX,
  					    rtm_ipv4_policy, extack);

  	if (err < 0)
  		return err;
  
  	for (i = 0; i <= RTA_MAX; ++i) {
  		int ifindex;
  
  		if (!tb[i])
  			continue;
  
  		switch (i) {
  		case RTA_TABLE:
  			filter->table_id = nla_get_u32(tb[i]);
  			break;
  		case RTA_OIF:
  			ifindex = nla_get_u32(tb[i]);
  			filter->dev = __dev_get_by_index(net, ifindex);
  			if (!filter->dev)
  				return -ENODEV;
  			break;
  		default:
  			NL_SET_ERR_MSG(extack, "Unsupported attribute in dump request");
  			return -EINVAL;
  		}
  	}
  
  	if (filter->flags || filter->protocol || filter->rt_type ||
  	    filter->table_id || filter->dev) {
  		filter->filter_set = 1;
  		cb->answer_flags = NLM_F_DUMP_FILTERED;

  	}
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(ip_valid_fib_dump_req);

  static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)

  {

  	struct fib_dump_filter filter = { .dump_routes = true,
  					  .dump_exceptions = true };

  	const struct nlmsghdr *nlh = cb->nlh;

  	struct net *net = sock_net(skb->sk);

  	unsigned int h, s_h;
  	unsigned int e = 0, s_e;

  	struct fib_table *tb;

  	struct hlist_head *head;

  	int dumped = 0, err;

  	if (cb->strict_check) {

  		err = ip_valid_fib_dump_req(net, nlh, &filter, cb);

  		if (err < 0)
  			return err;

  	} else if (nlmsg_len(nlh) >= sizeof(struct rtmsg)) {
  		struct rtmsg *rtm = nlmsg_data(nlh);
  
  		filter.flags = rtm->rtm_flags & (RTM_F_PREFIX | RTM_F_CLONED);

  	}

  	/* ipv4 does not use prefix flag */
  	if (filter.flags & RTM_F_PREFIX)

  		return skb->len;

  	if (filter.table_id) {
  		tb = fib_get_table(net, filter.table_id);
  		if (!tb) {

  			if (filter.dump_all_families)
  				return skb->len;

  			NL_SET_ERR_MSG(cb->extack, "ipv4: FIB table does not exist");
  			return -ENOENT;
  		}
  
  		err = fib_table_dump(tb, skb, cb, &filter);
  		return skb->len ? : err;
  	}

  	s_h = cb->args[0];
  	s_e = cb->args[1];

  	rcu_read_lock();

  	for (h = s_h; h < FIB_TABLE_HASHSZ; h++, s_e = 0) {
  		e = 0;

  		head = &net->ipv4.fib_table_hash[h];

  		hlist_for_each_entry_rcu(tb, head, tb_hlist) {

  			if (e < s_e)
  				goto next;
  			if (dumped)
  				memset(&cb->args[2], 0, sizeof(cb->args) -

  						 2 * sizeof(cb->args[0]));

  			err = fib_table_dump(tb, skb, cb, &filter);

  			if (err < 0) {
  				if (likely(skb->len))
  					goto out;
  
  				goto out_err;
  			}

  			dumped = 1;
  next:
  			e++;
  		}

  	}

  out:

  	err = skb->len;
  out_err:

  	rcu_read_unlock();

  	cb->args[1] = e;
  	cb->args[0] = h;

  	return err;

  }
  
  /* Prepare and feed intra-kernel routing request.

   * Really, it should be netlink message, but :-( netlink
   * can be not configured, so that we feed it directly
   * to fib engine. It is legal, because all events occur
   * only when netlink is already locked.

   */

  static void fib_magic(int cmd, int type, __be32 dst, int dst_len,
  		      struct in_ifaddr *ifa, u32 rt_priority)

  {

  	struct net *net = dev_net(ifa->ifa_dev->dev);

  	u32 tb_id = l3mdev_fib_table(ifa->ifa_dev->dev);

  	struct fib_table *tb;
  	struct fib_config cfg = {
  		.fc_protocol = RTPROT_KERNEL,
  		.fc_type = type,
  		.fc_dst = dst,
  		.fc_dst_len = dst_len,

  		.fc_priority = rt_priority,

  		.fc_prefsrc = ifa->ifa_local,
  		.fc_oif = ifa->ifa_dev->dev->ifindex,
  		.fc_nlflags = NLM_F_CREATE | NLM_F_APPEND,

  		.fc_nlinfo = {

  			.nl_net = net,

  		},

  	};

  	if (!tb_id)
  		tb_id = (type == RTN_UNICAST) ? RT_TABLE_MAIN : RT_TABLE_LOCAL;

  	tb = fib_new_table(net, tb_id);

  	if (!tb)

  		return;

  	cfg.fc_table = tb->tb_id;

  	if (type != RTN_LOCAL)
  		cfg.fc_scope = RT_SCOPE_LINK;
  	else
  		cfg.fc_scope = RT_SCOPE_HOST;

  
  	if (cmd == RTM_NEWROUTE)

  		fib_table_insert(net, tb, &cfg, NULL);

  	else

  		fib_table_delete(net, tb, &cfg, NULL);

  }

  void fib_add_ifaddr(struct in_ifaddr *ifa)

  {
  	struct in_device *in_dev = ifa->ifa_dev;
  	struct net_device *dev = in_dev->dev;
  	struct in_ifaddr *prim = ifa;

  	__be32 mask = ifa->ifa_mask;
  	__be32 addr = ifa->ifa_local;

  	__be32 prefix = ifa->ifa_address & mask;

  	if (ifa->ifa_flags & IFA_F_SECONDARY) {

  		prim = inet_ifa_byprefix(in_dev, prefix, mask);

  		if (!prim) {

  			pr_warn("%s: bug: prim == NULL
  ", __func__);

  			return;
  		}
  	}

  	fib_magic(RTM_NEWROUTE, RTN_LOCAL, addr, 32, prim, 0);

  	if (!(dev->flags & IFF_UP))

  		return;
  
  	/* Add broadcast address, if it is explicitly assigned. */

  	if (ifa->ifa_broadcast && ifa->ifa_broadcast != htonl(0xFFFFFFFF))

  		fib_magic(RTM_NEWROUTE, RTN_BROADCAST, ifa->ifa_broadcast, 32,
  			  prim, 0);

  	if (!ipv4_is_zeronet(prefix) && !(ifa->ifa_flags & IFA_F_SECONDARY) &&

  	    (prefix != addr || ifa->ifa_prefixlen < 32)) {

  		if (!(ifa->ifa_flags & IFA_F_NOPREFIXROUTE))
  			fib_magic(RTM_NEWROUTE,
  				  dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,

  				  prefix, ifa->ifa_prefixlen, prim,
  				  ifa->ifa_rt_priority);

  
  		/* Add network specific broadcasts, when it takes a sense */
  		if (ifa->ifa_prefixlen < 31) {

  			fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix, 32,
  				  prim, 0);

  			fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix | ~mask,

  				  32, prim, 0);

  		}
  	}
  }

  void fib_modify_prefix_metric(struct in_ifaddr *ifa, u32 new_metric)
  {
  	__be32 prefix = ifa->ifa_address & ifa->ifa_mask;
  	struct in_device *in_dev = ifa->ifa_dev;
  	struct net_device *dev = in_dev->dev;
  
  	if (!(dev->flags & IFF_UP) ||
  	    ifa->ifa_flags & (IFA_F_SECONDARY | IFA_F_NOPREFIXROUTE) ||
  	    ipv4_is_zeronet(prefix) ||

  	    (prefix == ifa->ifa_local && ifa->ifa_prefixlen == 32))

  		return;
  
  	/* add the new */
  	fib_magic(RTM_NEWROUTE,
  		  dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,
  		  prefix, ifa->ifa_prefixlen, ifa, new_metric);
  
  	/* delete the old */
  	fib_magic(RTM_DELROUTE,
  		  dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,
  		  prefix, ifa->ifa_prefixlen, ifa, ifa->ifa_rt_priority);
  }

  /* Delete primary or secondary address.
   * Optionally, on secondary address promotion consider the addresses
   * from subnet iprim as deleted, even if they are in device list.
   * In this case the secondary ifa can be in device list.
   */
  void fib_del_ifaddr(struct in_ifaddr *ifa, struct in_ifaddr *iprim)

  {
  	struct in_device *in_dev = ifa->ifa_dev;
  	struct net_device *dev = in_dev->dev;
  	struct in_ifaddr *ifa1;

  	struct in_ifaddr *prim = ifa, *prim1 = NULL;

  	__be32 brd = ifa->ifa_address | ~ifa->ifa_mask;
  	__be32 any = ifa->ifa_address & ifa->ifa_mask;

  #define LOCAL_OK	1
  #define BRD_OK		2
  #define BRD0_OK		4
  #define BRD1_OK		8

  	unsigned int ok = 0;

  	int subnet = 0;		/* Primary network */
  	int gone = 1;		/* Address is missing */
  	int same_prefsrc = 0;	/* Another primary with same IP */

  	if (ifa->ifa_flags & IFA_F_SECONDARY) {

  		prim = inet_ifa_byprefix(in_dev, any, ifa->ifa_mask);

  		if (!prim) {

  			/* if the device has been deleted, we don't perform
  			 * address promotion
  			 */
  			if (!in_dev->dead)
  				pr_warn("%s: bug: prim == NULL
  ", __func__);

  			return;
  		}

  		if (iprim && iprim != prim) {

  			pr_warn("%s: bug: iprim != prim
  ", __func__);

  			return;
  		}
  	} else if (!ipv4_is_zeronet(any) &&
  		   (any != ifa->ifa_local || ifa->ifa_prefixlen < 32)) {

  		if (!(ifa->ifa_flags & IFA_F_NOPREFIXROUTE))
  			fib_magic(RTM_DELROUTE,
  				  dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,

  				  any, ifa->ifa_prefixlen, prim, 0);

  		subnet = 1;

  	}

  	if (in_dev->dead)
  		goto no_promotions;

  	/* Deletion is more complicated than add.

  	 * We should take care of not to delete too much :-)
  	 *
  	 * Scan address list to be sure that addresses are really gone.

  	 */

  	rcu_read_lock();
  	in_dev_for_each_ifa_rcu(ifa1, in_dev) {

  		if (ifa1 == ifa) {
  			/* promotion, keep the IP */
  			gone = 0;
  			continue;
  		}
  		/* Ignore IFAs from our subnet */
  		if (iprim && ifa1->ifa_mask == iprim->ifa_mask &&
  		    inet_ifa_match(ifa1->ifa_address, iprim))
  			continue;
  
  		/* Ignore ifa1 if it uses different primary IP (prefsrc) */
  		if (ifa1->ifa_flags & IFA_F_SECONDARY) {
  			/* Another address from our subnet? */
  			if (ifa1->ifa_mask == prim->ifa_mask &&
  			    inet_ifa_match(ifa1->ifa_address, prim))
  				prim1 = prim;
  			else {
  				/* We reached the secondaries, so
  				 * same_prefsrc should be determined.
  				 */
  				if (!same_prefsrc)
  					continue;
  				/* Search new prim1 if ifa1 is not
  				 * using the current prim1
  				 */
  				if (!prim1 ||
  				    ifa1->ifa_mask != prim1->ifa_mask ||
  				    !inet_ifa_match(ifa1->ifa_address, prim1))
  					prim1 = inet_ifa_byprefix(in_dev,
  							ifa1->ifa_address,
  							ifa1->ifa_mask);
  				if (!prim1)
  					continue;
  				if (prim1->ifa_local != prim->ifa_local)
  					continue;
  			}
  		} else {
  			if (prim->ifa_local != ifa1->ifa_local)
  				continue;
  			prim1 = ifa1;
  			if (prim != prim1)
  				same_prefsrc = 1;
  		}

  		if (ifa->ifa_local == ifa1->ifa_local)
  			ok |= LOCAL_OK;
  		if (ifa->ifa_broadcast == ifa1->ifa_broadcast)
  			ok |= BRD_OK;
  		if (brd == ifa1->ifa_broadcast)
  			ok |= BRD1_OK;
  		if (any == ifa1->ifa_broadcast)
  			ok |= BRD0_OK;

  		/* primary has network specific broadcasts */
  		if (prim1 == ifa1 && ifa1->ifa_prefixlen < 31) {
  			__be32 brd1 = ifa1->ifa_address | ~ifa1->ifa_mask;
  			__be32 any1 = ifa1->ifa_address & ifa1->ifa_mask;
  
  			if (!ipv4_is_zeronet(any1)) {
  				if (ifa->ifa_broadcast == brd1 ||
  				    ifa->ifa_broadcast == any1)
  					ok |= BRD_OK;
  				if (brd == brd1 || brd == any1)
  					ok |= BRD1_OK;
  				if (any == brd1 || any == any1)
  					ok |= BRD0_OK;
  			}
  		}

  	}

  	rcu_read_unlock();

  no_promotions:

  	if (!(ok & BRD_OK))

  		fib_magic(RTM_DELROUTE, RTN_BROADCAST, ifa->ifa_broadcast, 32,
  			  prim, 0);

  	if (subnet && ifa->ifa_prefixlen < 31) {
  		if (!(ok & BRD1_OK))

  			fib_magic(RTM_DELROUTE, RTN_BROADCAST, brd, 32,
  				  prim, 0);

  		if (!(ok & BRD0_OK))

  			fib_magic(RTM_DELROUTE, RTN_BROADCAST, any, 32,
  				  prim, 0);

  	}

  	if (!(ok & LOCAL_OK)) {

  		unsigned int addr_type;

  		fib_magic(RTM_DELROUTE, RTN_LOCAL, ifa->ifa_local, 32, prim, 0);

  
  		/* Check, that this local address finally disappeared. */

  		addr_type = inet_addr_type_dev_table(dev_net(dev), dev,
  						     ifa->ifa_local);
  		if (gone && addr_type != RTN_LOCAL) {

  			/* And the last, but not the least thing.

  			 * We must flush stray FIB entries.
  			 *
  			 * First of all, we scan fib_info list searching
  			 * for stray nexthop entries, then ignite fib_flush.
  			 */

  			if (fib_sync_down_addr(dev, ifa->ifa_local))

  				fib_flush(dev_net(dev));

  		}
  	}
  #undef LOCAL_OK
  #undef BRD_OK
  #undef BRD0_OK
  #undef BRD1_OK
  }

  static void nl_fib_lookup(struct net *net, struct fib_result_nl *frn)

  {

  	struct fib_result       res;

  	struct flowi4           fl4 = {
  		.flowi4_mark = frn->fl_mark,
  		.daddr = frn->fl_addr,
  		.flowi4_tos = frn->fl_tos,
  		.flowi4_scope = frn->fl_scope,

  	};

  	struct fib_table *tb;
  
  	rcu_read_lock();
  
  	tb = fib_get_table(net, frn->tb_id_in);

  
  	frn->err = -ENOENT;

  	if (tb) {
  		local_bh_disable();
  
  		frn->tb_id = tb->tb_id;

  		frn->err = fib_table_lookup(tb, &fl4, &res, FIB_LOOKUP_NOREF);

  
  		if (!frn->err) {
  			frn->prefixlen = res.prefixlen;
  			frn->nh_sel = res.nh_sel;
  			frn->type = res.type;
  			frn->scope = res.scope;
  		}
  		local_bh_enable();
  	}

  
  	rcu_read_unlock();

  }

  static void nl_fib_input(struct sk_buff *skb)

  {

  	struct net *net;

  	struct fib_result_nl *frn;

  	struct nlmsghdr *nlh;

  	u32 portid;

  	net = sock_net(skb->sk);

  	nlh = nlmsg_hdr(skb);

  	if (skb->len < nlmsg_total_size(sizeof(*frn)) ||
  	    skb->len < nlh->nlmsg_len ||

  	    nlmsg_len(nlh) < sizeof(*frn))

  		return;

  	skb = netlink_skb_clone(skb, GFP_KERNEL);

  	if (!skb)

  		return;
  	nlh = nlmsg_hdr(skb);

  	frn = (struct fib_result_nl *) nlmsg_data(nlh);

  	nl_fib_lookup(net, frn);

  	portid = NETLINK_CB(skb).portid;      /* netlink portid */

  	NETLINK_CB(skb).portid = 0;        /* from kernel */

  	NETLINK_CB(skb).dst_group = 0;  /* unicast */

  	netlink_unicast(net->ipv4.fibnl, skb, portid, MSG_DONTWAIT);

  }

  static int __net_init nl_fib_lookup_init(struct net *net)

  {

  	struct sock *sk;

  	struct netlink_kernel_cfg cfg = {
  		.input	= nl_fib_input,
  	};

  	sk = netlink_kernel_create(net, NETLINK_FIB_LOOKUP, &cfg);

  	if (!sk)

  		return -EAFNOSUPPORT;

  	net->ipv4.fibnl = sk;

  	return 0;
  }
  
  static void nl_fib_lookup_exit(struct net *net)
  {

  	netlink_kernel_release(net->ipv4.fibnl);

  	net->ipv4.fibnl = NULL;

  }

  static void fib_disable_ip(struct net_device *dev, unsigned long event,
  			   bool force)

  {

  	if (fib_sync_down_dev(dev, event, force))

  		fib_flush(dev_net(dev));

  	else
  		rt_cache_flush(dev_net(dev));

  	arp_ifdown(dev);
  }
  
  static int fib_inetaddr_event(struct notifier_block *this, unsigned long event, void *ptr)
  {

  	struct in_ifaddr *ifa = (struct in_ifaddr *)ptr;

  	struct net_device *dev = ifa->ifa_dev->dev;

  	struct net *net = dev_net(dev);

  
  	switch (event) {
  	case NETDEV_UP:
  		fib_add_ifaddr(ifa);
  #ifdef CONFIG_IP_ROUTE_MULTIPATH

  		fib_sync_up(dev, RTNH_F_DEAD);

  #endif

  		atomic_inc(&net->ipv4.dev_addr_genid);

  		rt_cache_flush(dev_net(dev));

  		break;
  	case NETDEV_DOWN:

  		fib_del_ifaddr(ifa, NULL);

  		atomic_inc(&net->ipv4.dev_addr_genid);

  		if (!ifa->ifa_dev->ifa_list) {

  			/* Last address was deleted from this interface.

  			 * Disable IP.

  			 */

  			fib_disable_ip(dev, event, true);

  		} else {

  			rt_cache_flush(dev_net(dev));

  		}
  		break;
  	}
  	return NOTIFY_DONE;
  }
  
  static int fib_netdev_event(struct notifier_block *this, unsigned long event, void *ptr)
  {

  	struct net_device *dev = netdev_notifier_info_to_dev(ptr);

  	struct netdev_notifier_changeupper_info *upper_info = ptr;
  	struct netdev_notifier_info_ext *info_ext = ptr;

  	struct in_device *in_dev;

  	struct net *net = dev_net(dev);

  	struct in_ifaddr *ifa;

  	unsigned int flags;

  
  	if (event == NETDEV_UNREGISTER) {

  		fib_disable_ip(dev, event, true);

  		rt_flush_dev(dev);

  		return NOTIFY_DONE;
  	}

  	in_dev = __in_dev_get_rtnl(dev);

  	if (!in_dev)
  		return NOTIFY_DONE;

  	switch (event) {
  	case NETDEV_UP:

  		in_dev_for_each_ifa_rtnl(ifa, in_dev) {

  			fib_add_ifaddr(ifa);

  		}

  #ifdef CONFIG_IP_ROUTE_MULTIPATH

  		fib_sync_up(dev, RTNH_F_DEAD);

  #endif