// 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: semantics.
   *

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

   */

  #include <linux/uaccess.h>

  #include <linux/bitops.h>
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/jiffies.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_arp.h>
  #include <linux/proc_fs.h>
  #include <linux/skbuff.h>

  #include <linux/init.h>

  #include <linux/slab.h>

  #include <linux/netlink.h>

  #include <net/arp.h>

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

  #include <net/ip6_fib.h>

  #include <net/nexthop.h>

  #include <net/netlink.h>

  #include <net/rtnh.h>

  #include <net/lwtunnel.h>

  #include <net/fib_notifier.h>

  #include <net/addrconf.h>

  
  #include "fib_lookup.h"

  static DEFINE_SPINLOCK(fib_info_lock);

  static struct hlist_head *fib_info_hash;
  static struct hlist_head *fib_info_laddrhash;

  static unsigned int fib_info_hash_size;

  static unsigned int fib_info_cnt;
  
  #define DEVINDEX_HASHBITS 8
  #define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)
  static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];

  /* for_nexthops and change_nexthops only used when nexthop object
   * is not set in a fib_info. The logic within can reference fib_nh.
   */

  #ifdef CONFIG_IP_ROUTE_MULTIPATH

  #define for_nexthops(fi) {						\
  	int nhsel; const struct fib_nh *nh;				\
  	for (nhsel = 0, nh = (fi)->fib_nh;				\

  	     nhsel < fib_info_num_path((fi));				\

  	     nh++, nhsel++)
  
  #define change_nexthops(fi) {						\
  	int nhsel; struct fib_nh *nexthop_nh;				\
  	for (nhsel = 0,	nexthop_nh = (struct fib_nh *)((fi)->fib_nh);	\

  	     nhsel < fib_info_num_path((fi));				\

  	     nexthop_nh++, nhsel++)

  
  #else /* CONFIG_IP_ROUTE_MULTIPATH */
  
  /* Hope, that gcc will optimize it to get rid of dummy loop */

  #define for_nexthops(fi) {						\
  	int nhsel; const struct fib_nh *nh = (fi)->fib_nh;		\
  	for (nhsel = 0; nhsel < 1; nhsel++)

  #define change_nexthops(fi) {						\
  	int nhsel;							\
  	struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh);	\
  	for (nhsel = 0; nhsel < 1; nhsel++)

  
  #endif /* CONFIG_IP_ROUTE_MULTIPATH */
  
  #define endfor_nexthops(fi) }

  const struct fib_prop fib_props[RTN_MAX + 1] = {

  	[RTN_UNSPEC] = {

  		.error	= 0,
  		.scope	= RT_SCOPE_NOWHERE,

  	},
  	[RTN_UNICAST] = {

  		.error	= 0,
  		.scope	= RT_SCOPE_UNIVERSE,

  	},
  	[RTN_LOCAL] = {

  		.error	= 0,
  		.scope	= RT_SCOPE_HOST,

  	},
  	[RTN_BROADCAST] = {

  		.error	= 0,
  		.scope	= RT_SCOPE_LINK,

  	},
  	[RTN_ANYCAST] = {

  		.error	= 0,
  		.scope	= RT_SCOPE_LINK,

  	},
  	[RTN_MULTICAST] = {

  		.error	= 0,
  		.scope	= RT_SCOPE_UNIVERSE,

  	},
  	[RTN_BLACKHOLE] = {

  		.error	= -EINVAL,
  		.scope	= RT_SCOPE_UNIVERSE,

  	},
  	[RTN_UNREACHABLE] = {

  		.error	= -EHOSTUNREACH,
  		.scope	= RT_SCOPE_UNIVERSE,

  	},
  	[RTN_PROHIBIT] = {

  		.error	= -EACCES,
  		.scope	= RT_SCOPE_UNIVERSE,

  	},
  	[RTN_THROW] = {

  		.error	= -EAGAIN,
  		.scope	= RT_SCOPE_UNIVERSE,

  	},
  	[RTN_NAT] = {

  		.error	= -EINVAL,
  		.scope	= RT_SCOPE_NOWHERE,

  	},
  	[RTN_XRESOLVE] = {

  		.error	= -EINVAL,
  		.scope	= RT_SCOPE_NOWHERE,

  	},

  };

  static void rt_fibinfo_free(struct rtable __rcu **rtp)
  {
  	struct rtable *rt = rcu_dereference_protected(*rtp, 1);
  
  	if (!rt)
  		return;
  
  	/* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
  	 * because we waited an RCU grace period before calling
  	 * free_fib_info_rcu()
  	 */

  	dst_dev_put(&rt->dst);

  	dst_release_immediate(&rt->dst);

  }

  static void free_nh_exceptions(struct fib_nh_common *nhc)

  {

  	struct fnhe_hash_bucket *hash;

  	int i;

  	hash = rcu_dereference_protected(nhc->nhc_exceptions, 1);

  	if (!hash)
  		return;

  	for (i = 0; i < FNHE_HASH_SIZE; i++) {
  		struct fib_nh_exception *fnhe;

  		fnhe = rcu_dereference_protected(hash[i].chain, 1);

  		while (fnhe) {
  			struct fib_nh_exception *next;

  			next = rcu_dereference_protected(fnhe->fnhe_next, 1);

  			rt_fibinfo_free(&fnhe->fnhe_rth_input);
  			rt_fibinfo_free(&fnhe->fnhe_rth_output);

  			kfree(fnhe);
  
  			fnhe = next;
  		}
  	}
  	kfree(hash);
  }

  static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)

  {
  	int cpu;
  
  	if (!rtp)
  		return;
  
  	for_each_possible_cpu(cpu) {
  		struct rtable *rt;
  
  		rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);

  		if (rt) {

  			dst_dev_put(&rt->dst);

  			dst_release_immediate(&rt->dst);

  		}

  	}
  	free_percpu(rtp);
  }

  void fib_nh_common_release(struct fib_nh_common *nhc)
  {
  	if (nhc->nhc_dev)
  		dev_put(nhc->nhc_dev);
  
  	lwtstate_put(nhc->nhc_lwtstate);

  	rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
  	rt_fibinfo_free(&nhc->nhc_rth_input);

  	free_nh_exceptions(nhc);

  }
  EXPORT_SYMBOL_GPL(fib_nh_common_release);

  void fib_nh_release(struct net *net, struct fib_nh *fib_nh)
  {
  #ifdef CONFIG_IP_ROUTE_CLASSID
  	if (fib_nh->nh_tclassid)
  		net->ipv4.fib_num_tclassid_users--;
  #endif

  	fib_nh_common_release(&fib_nh->nh_common);

  }

  /* Release a nexthop info record */

  static void free_fib_info_rcu(struct rcu_head *head)
  {
  	struct fib_info *fi = container_of(head, struct fib_info, rcu);

  	if (fi->nh) {
  		nexthop_put(fi->nh);
  	} else {
  		change_nexthops(fi) {
  			fib_nh_release(fi->fib_net, nexthop_nh);
  		} endfor_nexthops(fi);
  	}

  	ip_fib_metrics_put(fi->fib_metrics);

  	kfree(fi);
  }

  
  void free_fib_info(struct fib_info *fi)
  {
  	if (fi->fib_dead == 0) {

  		pr_warn("Freeing alive fib_info %p
  ", fi);

  		return;
  	}

  	fib_info_cnt--;

  	call_rcu(&fi->rcu, free_fib_info_rcu);

  }

  EXPORT_SYMBOL_GPL(free_fib_info);

  
  void fib_release_info(struct fib_info *fi)
  {

  	spin_lock_bh(&fib_info_lock);

  	if (fi && --fi->fib_treeref == 0) {
  		hlist_del(&fi->fib_hash);
  		if (fi->fib_prefsrc)
  			hlist_del(&fi->fib_lhash);

  		if (fi->nh) {
  			list_del(&fi->nh_list);
  		} else {
  			change_nexthops(fi) {
  				if (!nexthop_nh->fib_nh_dev)
  					continue;
  				hlist_del(&nexthop_nh->nh_hash);
  			} endfor_nexthops(fi)
  		}

  		fi->fib_dead = 1;
  		fib_info_put(fi);
  	}

  	spin_unlock_bh(&fib_info_lock);

  }

  static inline int nh_comp(struct fib_info *fi, struct fib_info *ofi)

  {

  	const struct fib_nh *onh;

  	if (fi->nh || ofi->nh)
  		return nexthop_cmp(fi->nh, ofi->nh) ? 0 : -1;
  
  	if (ofi->fib_nhs == 0)
  		return 0;

  	for_nexthops(fi) {

  		onh = fib_info_nh(ofi, nhsel);

  		if (nh->fib_nh_oif != onh->fib_nh_oif ||

  		    nh->fib_nh_gw_family != onh->fib_nh_gw_family ||

  		    nh->fib_nh_scope != onh->fib_nh_scope ||

  #ifdef CONFIG_IP_ROUTE_MULTIPATH

  		    nh->fib_nh_weight != onh->fib_nh_weight ||

  #endif

  #ifdef CONFIG_IP_ROUTE_CLASSID

  		    nh->nh_tclassid != onh->nh_tclassid ||
  #endif

  		    lwtunnel_cmp_encap(nh->fib_nh_lws, onh->fib_nh_lws) ||
  		    ((nh->fib_nh_flags ^ onh->fib_nh_flags) & ~RTNH_COMPARE_MASK))

  			return -1;

  
  		if (nh->fib_nh_gw_family == AF_INET &&
  		    nh->fib_nh_gw4 != onh->fib_nh_gw4)
  			return -1;
  
  		if (nh->fib_nh_gw_family == AF_INET6 &&
  		    ipv6_addr_cmp(&nh->fib_nh_gw6, &onh->fib_nh_gw6))
  			return -1;

  	} endfor_nexthops(fi);
  	return 0;
  }

  static inline unsigned int fib_devindex_hashfn(unsigned int val)
  {
  	unsigned int mask = DEVINDEX_HASHSIZE - 1;
  
  	return (val ^
  		(val >> DEVINDEX_HASHBITS) ^
  		(val >> (DEVINDEX_HASHBITS * 2))) & mask;
  }

  static unsigned int fib_info_hashfn_1(int init_val, u8 protocol, u8 scope,
  				      u32 prefsrc, u32 priority)
  {
  	unsigned int val = init_val;
  
  	val ^= (protocol << 8) | scope;
  	val ^= prefsrc;
  	val ^= priority;
  
  	return val;
  }
  
  static unsigned int fib_info_hashfn_result(unsigned int val)

  {

  	unsigned int mask = (fib_info_hash_size - 1);

  	return (val ^ (val >> 7) ^ (val >> 12)) & mask;
  }
  
  static inline unsigned int fib_info_hashfn(struct fib_info *fi)
  {
  	unsigned int val;
  
  	val = fib_info_hashfn_1(fi->fib_nhs, fi->fib_protocol,
  				fi->fib_scope, (__force u32)fi->fib_prefsrc,
  				fi->fib_priority);

  
  	if (fi->nh) {
  		val ^= fib_devindex_hashfn(fi->nh->id);
  	} else {
  		for_nexthops(fi) {
  			val ^= fib_devindex_hashfn(nh->fib_nh_oif);
  		} endfor_nexthops(fi)
  	}

  	return fib_info_hashfn_result(val);
  }
  
  /* no metrics, only nexthop id */
  static struct fib_info *fib_find_info_nh(struct net *net,
  					 const struct fib_config *cfg)
  {
  	struct hlist_head *head;
  	struct fib_info *fi;
  	unsigned int hash;
  
  	hash = fib_info_hashfn_1(fib_devindex_hashfn(cfg->fc_nh_id),
  				 cfg->fc_protocol, cfg->fc_scope,
  				 (__force u32)cfg->fc_prefsrc,
  				 cfg->fc_priority);
  	hash = fib_info_hashfn_result(hash);
  	head = &fib_info_hash[hash];
  
  	hlist_for_each_entry(fi, head, fib_hash) {
  		if (!net_eq(fi->fib_net, net))
  			continue;
  		if (!fi->nh || fi->nh->id != cfg->fc_nh_id)
  			continue;
  		if (cfg->fc_protocol == fi->fib_protocol &&
  		    cfg->fc_scope == fi->fib_scope &&
  		    cfg->fc_prefsrc == fi->fib_prefsrc &&
  		    cfg->fc_priority == fi->fib_priority &&
  		    cfg->fc_type == fi->fib_type &&
  		    cfg->fc_table == fi->fib_tb_id &&
  		    !((cfg->fc_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK))
  			return fi;
  	}
  
  	return NULL;

  }

  static struct fib_info *fib_find_info(struct fib_info *nfi)

  {
  	struct hlist_head *head;

  	struct fib_info *fi;
  	unsigned int hash;
  
  	hash = fib_info_hashfn(nfi);
  	head = &fib_info_hash[hash];

  	hlist_for_each_entry(fi, head, fib_hash) {

  		if (!net_eq(fi->fib_net, nfi->fib_net))

  			continue;

  		if (fi->fib_nhs != nfi->fib_nhs)
  			continue;
  		if (nfi->fib_protocol == fi->fib_protocol &&

  		    nfi->fib_scope == fi->fib_scope &&

  		    nfi->fib_prefsrc == fi->fib_prefsrc &&
  		    nfi->fib_priority == fi->fib_priority &&

  		    nfi->fib_type == fi->fib_type &&

  		    memcmp(nfi->fib_metrics, fi->fib_metrics,

  			   sizeof(u32) * RTAX_MAX) == 0 &&

  		    !((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK) &&

  		    nh_comp(fi, nfi) == 0)

  			return fi;
  	}
  
  	return NULL;
  }

  /* Check, that the gateway is already configured.

   * Used only by redirect accept routine.

   */

  int ip_fib_check_default(__be32 gw, struct net_device *dev)

  {
  	struct hlist_head *head;

  	struct fib_nh *nh;
  	unsigned int hash;

  	spin_lock(&fib_info_lock);

  
  	hash = fib_devindex_hashfn(dev->ifindex);
  	head = &fib_info_devhash[hash];

  	hlist_for_each_entry(nh, head, nh_hash) {

  		if (nh->fib_nh_dev == dev &&
  		    nh->fib_nh_gw4 == gw &&
  		    !(nh->fib_nh_flags & RTNH_F_DEAD)) {

  			spin_unlock(&fib_info_lock);

  			return 0;
  		}
  	}

  	spin_unlock(&fib_info_lock);

  
  	return -1;
  }

  static inline size_t fib_nlmsg_size(struct fib_info *fi)
  {
  	size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
  			 + nla_total_size(4) /* RTA_TABLE */
  			 + nla_total_size(4) /* RTA_DST */
  			 + nla_total_size(4) /* RTA_PRIORITY */

  			 + nla_total_size(4) /* RTA_PREFSRC */
  			 + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */

  	unsigned int nhs = fib_info_num_path(fi);

  
  	/* space for nested metrics */
  	payload += nla_total_size((RTAX_MAX * nla_total_size(4)));

  	if (fi->nh)
  		payload += nla_total_size(4); /* RTA_NH_ID */

  	if (nhs) {

  		size_t nh_encapsize = 0;

  		/* Also handles the special case nhs == 1 */

  
  		/* each nexthop is packed in an attribute */
  		size_t nhsize = nla_total_size(sizeof(struct rtnexthop));

  		unsigned int i;

  
  		/* may contain flow and gateway attribute */
  		nhsize += 2 * nla_total_size(4);

  		/* grab encap info */

  		for (i = 0; i < fib_info_num_path(fi); i++) {
  			struct fib_nh_common *nhc = fib_info_nhc(fi, i);
  
  			if (nhc->nhc_lwtstate) {

  				/* RTA_ENCAP_TYPE */
  				nh_encapsize += lwtunnel_get_encap_size(

  						nhc->nhc_lwtstate);

  				/* RTA_ENCAP */
  				nh_encapsize +=  nla_total_size(2);
  			}

  		}

  		/* all nexthops are packed in a nested attribute */

  		payload += nla_total_size((nhs * nhsize) + nh_encapsize);

  	}
  
  	return payload;
  }

  void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,

  	       int dst_len, u32 tb_id, const struct nl_info *info,

  	       unsigned int nlm_flags)

  {

  	struct fib_rt_info fri;

  	struct sk_buff *skb;

  	u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;

  	int err = -ENOBUFS;

  	skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);

  	if (!skb)

  		goto errout;

  	fri.fi = fa->fa_info;
  	fri.tb_id = tb_id;
  	fri.dst = key;
  	fri.dst_len = dst_len;
  	fri.tos = fa->fa_tos;
  	fri.type = fa->fa_type;

  	fri.offload = fa->offload;
  	fri.trap = fa->trap;

  	err = fib_dump_info(skb, info->portid, seq, event, &fri, nlm_flags);

  	if (err < 0) {
  		/* -EMSGSIZE implies BUG in fib_nlmsg_size() */
  		WARN_ON(err == -EMSGSIZE);
  		kfree_skb(skb);
  		goto errout;
  	}

  	rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,

  		    info->nlh, GFP_KERNEL);
  	return;

  errout:
  	if (err < 0)

  		rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);

  }

  static int fib_detect_death(struct fib_info *fi, int order,
  			    struct fib_info **last_resort, int *last_idx,
  			    int dflt)

  {

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

  	struct neighbour *n;
  	int state = NUD_NONE;

  	if (likely(nhc->nhc_gw_family == AF_INET))
  		n = neigh_lookup(&arp_tbl, &nhc->nhc_gw.ipv4, nhc->nhc_dev);
  	else if (nhc->nhc_gw_family == AF_INET6)
  		n = neigh_lookup(ipv6_stub->nd_tbl, &nhc->nhc_gw.ipv6,
  				 nhc->nhc_dev);
  	else
  		n = NULL;

  	if (n) {
  		state = n->nud_state;
  		neigh_release(n);

  	} else {
  		return 0;

  	}

  	if (state == NUD_REACHABLE)

  		return 0;

  	if ((state & NUD_VALID) && order != dflt)

  		return 0;

  	if ((state & NUD_VALID) ||

  	    (*last_idx < 0 && order > dflt && state != NUD_INCOMPLETE)) {

  		*last_resort = fi;
  		*last_idx = order;
  	}
  	return 1;
  }

  int fib_nh_common_init(struct net *net, struct fib_nh_common *nhc,
  		       struct nlattr *encap, u16 encap_type,
  		       void *cfg, gfp_t gfp_flags,

  		       struct netlink_ext_ack *extack)
  {

  	int err;
  
  	nhc->nhc_pcpu_rth_output = alloc_percpu_gfp(struct rtable __rcu *,
  						    gfp_flags);
  	if (!nhc->nhc_pcpu_rth_output)
  		return -ENOMEM;

  	if (encap) {
  		struct lwtunnel_state *lwtstate;

  
  		if (encap_type == LWTUNNEL_ENCAP_NONE) {
  			NL_SET_ERR_MSG(extack, "LWT encap type not specified");

  			err = -EINVAL;
  			goto lwt_failure;

  		}

  		err = lwtunnel_build_state(net, encap_type, encap,
  					   nhc->nhc_family, cfg, &lwtstate,
  					   extack);

  		if (err)

  			goto lwt_failure;

  
  		nhc->nhc_lwtstate = lwtstate_get(lwtstate);
  	}
  
  	return 0;

  
  lwt_failure:
  	rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
  	nhc->nhc_pcpu_rth_output = NULL;
  	return err;

  }
  EXPORT_SYMBOL_GPL(fib_nh_common_init);

  int fib_nh_init(struct net *net, struct fib_nh *nh,
  		struct fib_config *cfg, int nh_weight,
  		struct netlink_ext_ack *extack)
  {

  	int err;

  	nh->fib_nh_family = AF_INET;

  	err = fib_nh_common_init(net, &nh->nh_common, cfg->fc_encap,

  				 cfg->fc_encap_type, cfg, GFP_KERNEL, extack);
  	if (err)

  		return err;

  	nh->fib_nh_oif = cfg->fc_oif;

  	nh->fib_nh_gw_family = cfg->fc_gw_family;
  	if (cfg->fc_gw_family == AF_INET)

  		nh->fib_nh_gw4 = cfg->fc_gw4;

  	else if (cfg->fc_gw_family == AF_INET6)
  		nh->fib_nh_gw6 = cfg->fc_gw6;

  	nh->fib_nh_flags = cfg->fc_flags;

  
  #ifdef CONFIG_IP_ROUTE_CLASSID
  	nh->nh_tclassid = cfg->fc_flow;
  	if (nh->nh_tclassid)
  		net->ipv4.fib_num_tclassid_users++;
  #endif
  #ifdef CONFIG_IP_ROUTE_MULTIPATH

  	nh->fib_nh_weight = nh_weight;

  #endif
  	return 0;

  }

  #ifdef CONFIG_IP_ROUTE_MULTIPATH

  static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining,
  			      struct netlink_ext_ack *extack)

  {
  	int nhs = 0;

  	while (rtnh_ok(rtnh, remaining)) {

  		nhs++;

  		rtnh = rtnh_next(rtnh, &remaining);
  	}
  
  	/* leftover implies invalid nexthop configuration, discard it */

  	if (remaining > 0) {
  		NL_SET_ERR_MSG(extack,
  			       "Invalid nexthop configuration - extra data after nexthops");
  		nhs = 0;
  	}
  
  	return nhs;

  }

  /* only called when fib_nh is integrated into fib_info */

  static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,

  		       int remaining, struct fib_config *cfg,
  		       struct netlink_ext_ack *extack)

  {

  	struct net *net = fi->fib_net;
  	struct fib_config fib_cfg;

  	struct fib_nh *nh;

  	int ret;

  	change_nexthops(fi) {

  		int attrlen;

  		memset(&fib_cfg, 0, sizeof(fib_cfg));

  		if (!rtnh_ok(rtnh, remaining)) {
  			NL_SET_ERR_MSG(extack,
  				       "Invalid nexthop configuration - extra data after nexthop");

  			return -EINVAL;

  		}

  		if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
  			NL_SET_ERR_MSG(extack,
  				       "Invalid flags for nexthop - can not contain DEAD or LINKDOWN");

  			return -EINVAL;

  		}

  		fib_cfg.fc_flags = (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
  		fib_cfg.fc_oif = rtnh->rtnh_ifindex;

  
  		attrlen = rtnh_attrlen(rtnh);
  		if (attrlen > 0) {

  			struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);

  
  			nla = nla_find(attrs, attrlen, RTA_GATEWAY);

  			nlav = nla_find(attrs, attrlen, RTA_VIA);
  			if (nla && nlav) {
  				NL_SET_ERR_MSG(extack,
  					       "Nexthop configuration can not contain both GATEWAY and VIA");
  				return -EINVAL;
  			}

  			if (nla) {

  				fib_cfg.fc_gw4 = nla_get_in_addr(nla);

  				if (fib_cfg.fc_gw4)
  					fib_cfg.fc_gw_family = AF_INET;

  			} else if (nlav) {
  				ret = fib_gw_from_via(&fib_cfg, nlav, extack);
  				if (ret)
  					goto errout;

  			}

  			nla = nla_find(attrs, attrlen, RTA_FLOW);

  			if (nla)
  				fib_cfg.fc_flow = nla_get_u32(nla);
  
  			fib_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);
  			nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
  			if (nla)
  				fib_cfg.fc_encap_type = nla_get_u16(nla);

  		}

  		ret = fib_nh_init(net, nexthop_nh, &fib_cfg,
  				  rtnh->rtnh_hops + 1, extack);
  		if (ret)
  			goto errout;

  		rtnh = rtnh_next(rtnh, &remaining);

  	} endfor_nexthops(fi);

  	ret = -EINVAL;

  	nh = fib_info_nh(fi, 0);
  	if (cfg->fc_oif && nh->fib_nh_oif != cfg->fc_oif) {

  		NL_SET_ERR_MSG(extack,
  			       "Nexthop device index does not match RTA_OIF");
  		goto errout;
  	}

  	if (cfg->fc_gw_family) {

  		if (cfg->fc_gw_family != nh->fib_nh_gw_family ||

  		    (cfg->fc_gw_family == AF_INET &&

  		     nh->fib_nh_gw4 != cfg->fc_gw4) ||

  		    (cfg->fc_gw_family == AF_INET6 &&

  		     ipv6_addr_cmp(&nh->fib_nh_gw6, &cfg->fc_gw6))) {

  			NL_SET_ERR_MSG(extack,

  				       "Nexthop gateway does not match RTA_GATEWAY or RTA_VIA");

  			goto errout;
  		}

  	}
  #ifdef CONFIG_IP_ROUTE_CLASSID

  	if (cfg->fc_flow && nh->nh_tclassid != cfg->fc_flow) {

  		NL_SET_ERR_MSG(extack,
  			       "Nexthop class id does not match RTA_FLOW");
  		goto errout;
  	}
  #endif
  	ret = 0;

  errout:
  	return ret;

  }

  /* only called when fib_nh is integrated into fib_info */

  static void fib_rebalance(struct fib_info *fi)
  {
  	int total;
  	int w;

  	if (fib_info_num_path(fi) < 2)

  		return;
  
  	total = 0;
  	for_nexthops(fi) {

  		if (nh->fib_nh_flags & RTNH_F_DEAD)

  			continue;

  		if (ip_ignore_linkdown(nh->fib_nh_dev) &&
  		    nh->fib_nh_flags & RTNH_F_LINKDOWN)

  			continue;

  		total += nh->fib_nh_weight;

  	} endfor_nexthops(fi);
  
  	w = 0;
  	change_nexthops(fi) {
  		int upper_bound;

  		if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD) {

  			upper_bound = -1;

  		} else if (ip_ignore_linkdown(nexthop_nh->fib_nh_dev) &&
  			   nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN) {

  			upper_bound = -1;
  		} else {

  			w += nexthop_nh->fib_nh_weight;

  			upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
  							    total) - 1;

  		}

  		atomic_set(&nexthop_nh->fib_nh_upper_bound, upper_bound);

  	} endfor_nexthops(fi);

  }

  #else /* CONFIG_IP_ROUTE_MULTIPATH */

  static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
  		       int remaining, struct fib_config *cfg,
  		       struct netlink_ext_ack *extack)
  {
  	NL_SET_ERR_MSG(extack, "Multipath support not enabled in kernel");
  
  	return -EINVAL;
  }

  #define fib_rebalance(fi) do { } while (0)

  
  #endif /* CONFIG_IP_ROUTE_MULTIPATH */

  static int fib_encap_match(struct net *net, u16 encap_type,

  			   struct nlattr *encap,

  			   const struct fib_nh *nh,

  			   const struct fib_config *cfg,
  			   struct netlink_ext_ack *extack)

  {
  	struct lwtunnel_state *lwtstate;

  	int ret, result = 0;

  
  	if (encap_type == LWTUNNEL_ENCAP_NONE)
  		return 0;

  	ret = lwtunnel_build_state(net, encap_type, encap, AF_INET,

  				   cfg, &lwtstate, extack);

  	if (!ret) {

  		result = lwtunnel_cmp_encap(lwtstate, nh->fib_nh_lws);

  		lwtstate_free(lwtstate);
  	}

  	return result;

  }

  int fib_nh_match(struct net *net, struct fib_config *cfg, struct fib_info *fi,

  		 struct netlink_ext_ack *extack)

  {
  #ifdef CONFIG_IP_ROUTE_MULTIPATH

  	struct rtnexthop *rtnh;
  	int remaining;

  #endif

  	if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)

  		return 1;

  	if (cfg->fc_nh_id) {
  		if (fi->nh && cfg->fc_nh_id == fi->nh->id)
  			return 0;
  		return 1;
  	}

  	if (cfg->fc_oif || cfg->fc_gw_family) {

  		struct fib_nh *nh = fib_info_nh(fi, 0);

  		if (cfg->fc_encap) {

  			if (fib_encap_match(net, cfg->fc_encap_type,
  					    cfg->fc_encap, nh, cfg, extack))

  				return 1;

  		}

  #ifdef CONFIG_IP_ROUTE_CLASSID
  		if (cfg->fc_flow &&

  		    cfg->fc_flow != nh->nh_tclassid)

  			return 1;
  #endif

  		if ((cfg->fc_oif && cfg->fc_oif != nh->fib_nh_oif) ||

  		    (cfg->fc_gw_family &&

  		     cfg->fc_gw_family != nh->fib_nh_gw_family))

  			return 1;
  
  		if (cfg->fc_gw_family == AF_INET &&

  		    cfg->fc_gw4 != nh->fib_nh_gw4)

  			return 1;

  		if (cfg->fc_gw_family == AF_INET6 &&

  		    ipv6_addr_cmp(&cfg->fc_gw6, &nh->fib_nh_gw6))

  			return 1;

  		return 0;

  	}
  
  #ifdef CONFIG_IP_ROUTE_MULTIPATH

  	if (!cfg->fc_mp)

  		return 0;

  
  	rtnh = cfg->fc_mp;
  	remaining = cfg->fc_mp_len;

  	for_nexthops(fi) {

  		int attrlen;

  		if (!rtnh_ok(rtnh, remaining))

  			return -EINVAL;

  		if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->fib_nh_oif)

  			return 1;

  
  		attrlen = rtnh_attrlen(rtnh);

  		if (attrlen > 0) {

  			struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);

  
  			nla = nla_find(attrs, attrlen, RTA_GATEWAY);

  			nlav = nla_find(attrs, attrlen, RTA_VIA);
  			if (nla && nlav) {
  				NL_SET_ERR_MSG(extack,
  					       "Nexthop configuration can not contain both GATEWAY and VIA");
  				return -EINVAL;
  			}
  
  			if (nla) {
  				if (nh->fib_nh_gw_family != AF_INET ||
  				    nla_get_in_addr(nla) != nh->fib_nh_gw4)
  					return 1;
  			} else if (nlav) {
  				struct fib_config cfg2;
  				int err;
  
  				err = fib_gw_from_via(&cfg2, nlav, extack);
  				if (err)
  					return err;
  
  				switch (nh->fib_nh_gw_family) {
  				case AF_INET:
  					if (cfg2.fc_gw_family != AF_INET ||
  					    cfg2.fc_gw4 != nh->fib_nh_gw4)
  						return 1;
  					break;
  				case AF_INET6:
  					if (cfg2.fc_gw_family != AF_INET6 ||
  					    ipv6_addr_cmp(&cfg2.fc_gw6,
  							  &nh->fib_nh_gw6))
  						return 1;
  					break;
  				}
  			}

  #ifdef CONFIG_IP_ROUTE_CLASSID

  			nla = nla_find(attrs, attrlen, RTA_FLOW);
  			if (nla && nla_get_u32(nla) != nh->nh_tclassid)

  				return 1;
  #endif
  		}

  
  		rtnh = rtnh_next(rtnh, &remaining);

  	} endfor_nexthops(fi);
  #endif
  	return 0;
  }

  bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
  {
  	struct nlattr *nla;
  	int remaining;
  
  	if (!cfg->fc_mx)
  		return true;
  
  	nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
  		int type = nla_type(nla);

  		u32 fi_val, val;

  
  		if (!type)
  			continue;
  		if (type > RTAX_MAX)
  			return false;
  
  		if (type == RTAX_CC_ALGO) {
  			char tmp[TCP_CA_NAME_MAX];
  			bool ecn_ca = false;
  
  			nla_strlcpy(tmp, nla, sizeof(tmp));

  			val = tcp_ca_get_key_by_name(fi->fib_net, tmp, &ecn_ca);

  		} else {

  			if (nla_len(nla) != sizeof(u32))
  				return false;

  			val = nla_get_u32(nla);
  		}

  		fi_val = fi->fib_metrics->metrics[type - 1];
  		if (type == RTAX_FEATURES)
  			fi_val &= ~DST_FEATURE_ECN_CA;
  
  		if (fi_val != val)

  			return false;
  	}
  
  	return true;
  }

  static int fib_check_nh_v6_gw(struct net *net, struct fib_nh *nh,
  			      u32 table, struct netlink_ext_ack *extack)
  {
  	struct fib6_config cfg = {
  		.fc_table = table,
  		.fc_flags = nh->fib_nh_flags | RTF_GATEWAY,
  		.fc_ifindex = nh->fib_nh_oif,
  		.fc_gateway = nh->fib_nh_gw6,
  	};
  	struct fib6_nh fib6_nh = {};
  	int err;
  
  	err = ipv6_stub->fib6_nh_init(net, &fib6_nh, &cfg, GFP_KERNEL, extack);
  	if (!err) {
  		nh->fib_nh_dev = fib6_nh.fib_nh_dev;
  		dev_hold(nh->fib_nh_dev);
  		nh->fib_nh_oif = nh->fib_nh_dev->ifindex;
  		nh->fib_nh_scope = RT_SCOPE_LINK;
  
  		ipv6_stub->fib6_nh_release(&fib6_nh);
  	}
  
  	return err;
  }

  
  /*

   * Picture
   * -------
   *
   * Semantics of nexthop is very messy by historical reasons.
   * We have to take into account, that:
   * a) gateway can be actually local interface address,
   *    so that gatewayed route is direct.
   * b) gateway must be on-link address, possibly
   *    described not by an ifaddr, but also by a direct route.
   * c) If both gateway and interface are specified, they should not
   *    contradict.
   * d) If we use tunnel routes, gateway could be not on-link.
   *
   * Attempt to reconcile all of these (alas, self-contradictory) conditions
   * results in pretty ugly and hairy code with obscure logic.
   *
   * I chose to generalized it instead, so that the size
   * of code does not increase practically, but it becomes
   * much more general.
   * Every prefix is assigned a "scope" value: "host" is local address,
   * "link" is direct route,
   * [ ... "site" ... "interior" ... ]
   * and "universe" is true gateway route with global meaning.
   *
   * Every prefix refers to a set of "nexthop"s (gw, oif),
   * where gw must have narrower scope. This recursion stops
   * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
   * which means that gw is forced to be on link.
   *
   * Code is still hairy, but now it is apparently logically
   * consistent and very flexible. F.e. as by-product it allows
   * to co-exists in peace independent exterior and interior
   * routing processes.
   *
   * Normally it looks as following.
   *
   * {universe prefix}  -> (gw, oif) [scope link]
   *		  |
   *		  |-> {link prefix} -> (gw, oif) [scope local]
   *					|
   *					|-> {local prefix} (terminal node)

   */

  static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
  			      u8 scope, struct netlink_ext_ack *extack)

  {

  	struct net_device *dev;

  	struct fib_result res;

  	int err = 0;

  	if (nh->fib_nh_flags & RTNH_F_ONLINK) {
  		unsigned int addr_type;

  		if (scope >= RT_SCOPE_LINK) {
  			NL_SET_ERR_MSG(extack, "Nexthop has invalid scope");
  			return -EINVAL;

  		}

  		dev = __dev_get_by_index(net, nh->fib_nh_oif);
  		if (!dev) {
  			NL_SET_ERR_MSG(extack, "Nexthop device required for onlink");
  			return -ENODEV;

  		}

  		if (!(dev->flags & IFF_UP)) {
  			NL_SET_ERR_MSG(extack, "Nexthop device is not up");
  			return -ENETDOWN;

  		}

  		addr_type = inet_addr_type_dev_table(net, dev, nh->fib_nh_gw4);
  		if (addr_type != RTN_UNICAST) {
  			NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
  			return -EINVAL;

  		}

  		if (!netif_carrier_ok(dev))

  			nh->fib_nh_flags |= RTNH_F_LINKDOWN;

  		nh->fib_nh_dev = dev;
  		dev_hold(dev);
  		nh->fib_nh_scope = RT_SCOPE_LINK;
  		return 0;
  	}
  	rcu_read_lock();
  	{
  		struct fib_table *tbl = NULL;
  		struct flowi4 fl4 = {
  			.daddr = nh->fib_nh_gw4,
  			.flowi4_scope = scope + 1,
  			.flowi4_oif = nh->fib_nh_oif,
  			.flowi4_iif = LOOPBACK_IFINDEX,
  		};
  
  		/* It is not necessary, but requires a bit of thinking */
  		if (fl4.flowi4_scope < RT_SCOPE_LINK)
  			fl4.flowi4_scope = RT_SCOPE_LINK;

  		if (table && table != RT_TABLE_MAIN)

  			tbl = fib_get_table(net, table);
  
  		if (tbl)
  			err = fib_table_lookup(tbl, &fl4, &res,
  					       FIB_LOOKUP_IGNORE_LINKSTATE |
  					       FIB_LOOKUP_NOREF);
  
  		/* on error or if no table given do full lookup. This
  		 * is needed for example when nexthops are in the local
  		 * table rather than the given table
  		 */
  		if (!tbl || err) {
  			err = fib_lookup(net, &fl4, &res,
  					 FIB_LOOKUP_IGNORE_LINKSTATE);

  		}

  
  		if (err) {
  			NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");

  			goto out;

  		}

  	}

  
  	err = -EINVAL;
  	if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
  		NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
  		goto out;
  	}
  	nh->fib_nh_scope = res.scope;
  	nh->fib_nh_oif = FIB_RES_OIF(res);
  	nh->fib_nh_dev = dev = FIB_RES_DEV(res);
  	if (!dev) {
  		NL_SET_ERR_MSG(extack,
  			       "No egress device for nexthop gateway");
  		goto out;
  	}
  	dev_hold(dev);
  	if (!netif_carrier_ok(dev))
  		nh->fib_nh_flags |= RTNH_F_LINKDOWN;
  	err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;

  out:
  	rcu_read_unlock();
  	return err;

  }

  
  static int fib_check_nh_nongw(struct net *net, struct fib_nh *nh,
  			      struct netlink_ext_ack *extack)
  {
  	struct in_device *in_dev;
  	int err;
  
  	if (nh->fib_nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
  		NL_SET_ERR_MSG(extack,
  			       "Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
  		return -EINVAL;
  	}
  
  	rcu_read_lock();
  
  	err = -ENODEV;
  	in_dev = inetdev_by_index(net, nh->fib_nh_oif);
  	if (!in_dev)
  		goto out;
  	err = -ENETDOWN;
  	if (!(in_dev->dev->flags & IFF_UP)) {
  		NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
  		goto out;
  	}
  
  	nh->fib_nh_dev = in_dev->dev;
  	dev_hold(nh->fib_nh_dev);
  	nh->fib_nh_scope = RT_SCOPE_HOST;
  	if (!netif_carrier_ok(nh->fib_nh_dev))
  		nh->fib_nh_flags |= RTNH_F_LINKDOWN;
  	err = 0;
  out:
  	rcu_read_unlock();
  	return err;
  }

  int fib_check_nh(struct net *net, struct fib_nh *nh, u32 table, u8 scope,
  		 struct netlink_ext_ack *extack)

  {

  	int err;
  
  	if (nh->fib_nh_gw_family == AF_INET)

  		err = fib_check_nh_v4_gw(net, nh, table, scope, extack);

  	else if (nh->fib_nh_gw_family == AF_INET6)
  		err = fib_check_nh_v6_gw(net, nh, table, extack);

  	else
  		err = fib_check_nh_nongw(net, nh, extack);
  
  	return err;
  }

  static inline unsigned int fib_laddr_hashfn(__be32 val)

  {

  	unsigned int mask = (fib_info_hash_size - 1);

  	return ((__force u32)val ^
  		((__force u32)val >> 7) ^
  		((__force u32)val >> 14)) & mask;

  }

  static struct hlist_head *fib_info_hash_alloc(int bytes)

  {
  	if (bytes <= PAGE_SIZE)

  		return kzalloc(bytes, GFP_KERNEL);

  	else
  		return (struct hlist_head *)

  			__get_free_pages(GFP_KERNEL | __GFP_ZERO,
  					 get_order(bytes));

  }

  static void fib_info_hash_free(struct hlist_head *hash, int bytes)

  {
  	if (!hash)
  		return;
  
  	if (bytes <= PAGE_SIZE)
  		kfree(hash);
  	else
  		free_pages((unsigned long) hash, get_order(bytes));
  }

  static void fib_info_hash_move(struct hlist_head *new_info_hash,
  			       struct hlist_head *new_laddrhash,
  			       unsigned int new_size)

  {

  	struct hlist_head *old_info_hash, *old_laddrhash;

  	unsigned int old_size = fib_info_hash_size;

  	unsigned int i, bytes;

  	spin_lock_bh(&fib_info_lock);

  	old_info_hash = fib_info_hash;
  	old_laddrhash = fib_info_laddrhash;

  	fib_info_hash_size = new_size;

  
  	for (i = 0; i < old_size; i++) {
  		struct hlist_head *head = &fib_info_hash[i];

  		struct hlist_node *n;

  		struct fib_info *fi;

  		hlist_for_each_entry_safe(fi, n, head, fib_hash) {

  			struct hlist_head *dest;
  			unsigned int new_hash;

  			new_hash = fib_info_hashfn(fi);
  			dest = &new_info_hash[new_hash];
  			hlist_add_head(&fi->fib_hash, dest);
  		}
  	}
  	fib_info_hash = new_info_hash;
  
  	for (i = 0; i < old_size; i++) {
  		struct hlist_head *lhead = &fib_info_laddrhash[i];

  		struct hlist_node *n;

  		struct fib_info *fi;

  		hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {

  			struct hlist_head *ldest;
  			unsigned int new_hash;

  			new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
  			ldest = &new_laddrhash[new_hash];
  			hlist_add_head(&fi->fib_lhash, ldest);
  		}
  	}
  	fib_info_laddrhash = new_laddrhash;

  	spin_unlock_bh(&fib_info_lock);

  
  	bytes = old_size * sizeof(struct hlist_head *);

  	fib_info_hash_free(old_info_hash, bytes);
  	fib_info_hash_free(old_laddrhash, bytes);

  }

  __be32 fib_info_update_nhc_saddr(struct net *net, struct fib_nh_common *nhc,
  				 unsigned char scope)

  {

  	struct fib_nh *nh;
  
  	if (nhc->nhc_family != AF_INET)
  		return inet_select_addr(nhc->nhc_dev, 0, scope);
  
  	nh = container_of(nhc, struct fib_nh, nh_common);

  	nh->nh_saddr = inet_select_addr(nh->fib_nh_dev, nh->fib_nh_gw4, scope);

  	nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
  
  	return nh->nh_saddr;
  }

  __be32 fib_result_prefsrc(struct net *net, struct fib_result *res)
  {
  	struct fib_nh_common *nhc = res->nhc;

  
  	if (res->fi->fib_prefsrc)
  		return res->fi->fib_prefsrc;

  	if (nhc->nhc_family == AF_INET) {
  		struct fib_nh *nh;

  		nh = container_of(nhc, struct fib_nh, nh_common);
  		if (nh->nh_saddr_genid == atomic_read(&net->ipv4.dev_addr_genid))
  			return nh->nh_saddr;
  	}
  
  	return fib_info_update_nhc_saddr(net, nhc, res->fi->fib_scope);

  }

  static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
  {
  	if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
  	    fib_prefsrc != cfg->fc_dst) {

  		u32 tb_id = cfg->fc_table;

  		int rc;

  
  		if (tb_id == RT_TABLE_MAIN)
  			tb_id = RT_TABLE_LOCAL;

  		rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
  					  fib_prefsrc, tb_id);
  
  		if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
  			rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
  						  fib_prefsrc, RT_TABLE_LOCAL);

  		}

  
  		if (rc != RTN_LOCAL)
  			return false;

  	}
  	return true;
  }

  struct fib_info *fib_create_info(struct fib_config *cfg,
  				 struct netlink_ext_ack *extack)

  {
  	int err;
  	struct fib_info *fi = NULL;

  	struct nexthop *nh = NULL;

  	struct fib_info *ofi;

  	int nhs = 1;

  	struct net *net = cfg->fc_nlinfo.nl_net;

  	if (cfg->fc_type > RTN_MAX)
  		goto err_inval;

  	/* Fast check to catch the most weird cases */

  	if (fib_props[cfg->fc_type].scope > cfg->fc_scope) {
  		NL_SET_ERR_MSG(extack, "Invalid scope");

  		goto err_inval;

  	}

  	if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
  		NL_SET_ERR_MSG(extack,
  			       "Invalid rtm_flags - can not contain DEAD or LINKDOWN");

  		goto err_inval;

  	}

  	if (cfg->fc_nh_id) {

  		if (!cfg->fc_mx) {
  			fi = fib_find_info_nh(net, cfg);
  			if (fi) {
  				fi->fib_treeref++;
  				return fi;
  			}
  		}

  		nh = nexthop_find_by_id(net, cfg->fc_nh_id);
  		if (!nh) {
  			NL_SET_ERR_MSG(extack, "Nexthop id does not exist");
  			goto err_inval;
  		}
  		nhs = 0;
  	}

  #ifdef CONFIG_IP_ROUTE_MULTIPATH

  	if (cfg->fc_mp) {

  		nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len, extack);

  		if (nhs == 0)
  			goto err_inval;
  	}
  #endif

  
  	err = -ENOBUFS;

  	if (fib_info_cnt >= fib_info_hash_size) {
  		unsigned int new_size = fib_info_hash_size << 1;

  		struct hlist_head *new_info_hash;
  		struct hlist_head *new_laddrhash;
  		unsigned int bytes;
  
  		if (!new_size)

  			new_size = 16;

  		bytes = new_size * sizeof(struct hlist_head *);

  		new_info_hash = fib_info_hash_alloc(bytes);
  		new_laddrhash = fib_info_hash_alloc(bytes);

  		if (!new_info_hash || !new_laddrhash) {

  			fib_info_hash_free(new_info_hash, bytes);
  			fib_info_hash_free(new_laddrhash, bytes);

  		} else

  			fib_info_hash_move(new_info_hash, new_laddrhash, new_size);

  		if (!fib_info_hash_size)

  			goto failure;
  	}

  	fi = kzalloc(struct_size(fi, fib_nh, nhs), GFP_KERNEL);

  	if (!fi)

  		goto failure;

  	fi->fib_metrics = ip_fib_metrics_init(fi->fib_net, cfg->fc_mx,

  					      cfg->fc_mx_len, extack);

  	if (IS_ERR(fi->fib_metrics)) {

  		err = PTR_ERR(fi->fib_metrics);
  		kfree(fi);
  		return ERR_PTR(err);

  	}

  	fib_info_cnt++;

  	fi->fib_net = net;

  	fi->fib_protocol = cfg->fc_protocol;

  	fi->fib_scope = cfg->fc_scope;

  	fi->fib_flags = cfg->fc_flags;
  	fi->fib_priority = cfg->fc_priority;
  	fi->fib_prefsrc = cfg->fc_prefsrc;

  	fi->fib_type = cfg->fc_type;

  	fi->fib_tb_id = cfg->fc_table;

  
  	fi->fib_nhs = nhs;

  	if (nh) {
  		if (!nexthop_get(nh)) {
  			NL_SET_ERR_MSG(extack, "Nexthop has been deleted");
  			err = -EINVAL;
  		} else {
  			err = 0;
  			fi->nh = nh;
  		}
  	} else {
  		change_nexthops(fi) {
  			nexthop_nh->nh_parent = fi;
  		} endfor_nexthops(fi)

  		if (cfg->fc_mp)
  			err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg,
  					  extack);
  		else
  			err = fib_nh_init(net, fi->fib_nh, cfg, 1, extack);
  	}

  	if (err != 0)
  		goto failure;

  	if (fib_props[cfg->fc_type].error) {

  		if (cfg->fc_gw_family || cfg->fc_oif || cfg->fc_mp) {

  			NL_SET_ERR_MSG(extack,
  				       "Gateway, device and multipath can not be specified for this route type");

  			goto err_inval;

  		}

  		goto link_it;

  	} else {
  		switch (cfg->fc_type) {
  		case RTN_UNICAST:
  		case RTN_LOCAL:
  		case RTN_BROADCAST:
  		case RTN_ANYCAST:
  		case RTN_MULTICAST:
  			break;
  		default:

  			NL_SET_ERR_MSG(extack, "Invalid route type");

  			goto err_inval;
  		}

  	}

  	if (cfg->fc_scope > RT_SCOPE_HOST) {
  		NL_SET_ERR_MSG(extack, "Invalid scope");

  		goto err_inval;

  	}

  	if (fi->nh) {
  		err = fib_check_nexthop(fi->nh, cfg->fc_scope, extack);
  		if (err)
  			goto failure;
  	} else if (cfg->fc_scope == RT_SCOPE_HOST) {

  		struct fib_nh *nh = fi->fib_nh;
  
  		/* Local address is added. */

  		if (nhs != 1) {
  			NL_SET_ERR_MSG(extack,
  				       "Route with host scope can not have multiple nexthops");

  			goto err_inval;

  		}

  		if (nh->fib_nh_gw_family) {

  			NL_SET_ERR_MSG(extack,
  				       "Route with host scope can not have a gateway");

  			goto err_inval;

  		}

  		nh->fib_nh_scope = RT_SCOPE_NOWHERE;

  		nh->fib_nh_dev = dev_get_by_index(net, nh->fib_nh_oif);

  		err = -ENODEV;

  		if (!nh->fib_nh_dev)

  			goto failure;
  	} else {

  		int linkdown = 0;

  		change_nexthops(fi) {

  			err = fib_check_nh(cfg->fc_nlinfo.nl_net, nexthop_nh,
  					   cfg->fc_table, cfg->fc_scope,
  					   extack);

  			if (err != 0)

  				goto failure;

  			if (nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN)

  				linkdown++;

  		} endfor_nexthops(fi)

  		if (linkdown == fi->fib_nhs)
  			fi->fib_flags |= RTNH_F_LINKDOWN;

  	}

  	if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc)) {
  		NL_SET_ERR_MSG(extack, "Invalid prefsrc address");

  		goto err_inval;

  	}

  	if (!fi->nh) {
  		change_nexthops(fi) {
  			fib_info_update_nhc_saddr(net, &nexthop_nh->nh_common,
  						  fi->fib_scope);
  			if (nexthop_nh->fib_nh_gw_family == AF_INET6)
  				fi->fib_nh_is_v6 = true;
  		} endfor_nexthops(fi)

  		fib_rebalance(fi);
  	}

  link_it:

  	ofi = fib_find_info(fi);
  	if (ofi) {

  		fi->fib_dead = 1;
  		free_fib_info(fi);
  		ofi->fib_treeref++;
  		return ofi;
  	}
  
  	fi->fib_treeref++;

  	refcount_set(&fi->fib_clntref, 1);

  	spin_lock_bh(&fib_info_lock);

  	hlist_add_head(&fi->fib_hash,
  		       &fib_info_hash[fib_info_hashfn(fi)]);
  	if (fi->fib_prefsrc) {
  		struct hlist_head *head;
  
  		head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
  		hlist_add_head(&fi->fib_lhash, head);
  	}

  	if (fi->nh) {
  		list_add(&fi->nh_list, &nh->fi_list);
  	} else {
  		change_nexthops(fi) {
  			struct hlist_head *head;
  			unsigned int hash;

  			if (!nexthop_nh->fib_nh_dev)
  				continue;
  			hash = fib_devindex_hashfn(nexthop_nh->fib_nh_dev->ifindex);
  			head = &fib_info_devhash[hash];
  			hlist_add_head(&nexthop_nh->nh_hash, head);
  		} endfor_nexthops(fi)
  	}

  	spin_unlock_bh(&fib_info_lock);

  	return fi;
  
  err_inval:
  	err = -EINVAL;
  
  failure:

  	if (fi) {

  		fi->fib_dead = 1;
  		free_fib_info(fi);
  	}

  
  	return ERR_PTR(err);

  }

  int fib_nexthop_info(struct sk_buff *skb, const struct fib_nh_common *nhc,

  		     u8 rt_family, unsigned char *flags, bool skip_oif)

  {

  	if (nhc->nhc_flags & RTNH_F_DEAD)

  		*flags |= RTNH_F_DEAD;

  	if (nhc->nhc_flags & RTNH_F_LINKDOWN) {

  		*flags |= RTNH_F_LINKDOWN;
  
  		rcu_read_lock();

  		switch (nhc->nhc_family) {
  		case AF_INET:
  			if (ip_ignore_linkdown(nhc->nhc_dev))
  				*flags |= RTNH_F_DEAD;
  			break;

  		case AF_INET6:
  			if (ip6_ignore_linkdown(nhc->nhc_dev))
  				*flags |= RTNH_F_DEAD;
  			break;

  		}

  		rcu_read_unlock();
  	}

  	switch (nhc->nhc_gw_family) {
  	case AF_INET:
  		if (nla_put_in_addr(skb, RTA_GATEWAY, nhc->nhc_gw.ipv4))
  			goto nla_put_failure;
  		break;
  	case AF_INET6:

  		/* if gateway family does not match nexthop family
  		 * gateway is encoded as RTA_VIA
  		 */

  		if (rt_family != nhc->nhc_gw_family) {