Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2275 insertions, 0 deletions

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
new file mode 100644
index 0000000000..5eb1b8d302
--- /dev/null
+++ b/net/ipv4/fib_semantics.c
@@ -0,0 +1,2275 @@
+// 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 <linux/hash.h>
+#include <linux/nospec.h>
+
+#include <net/arp.h>
+#include <net/inet_dscp.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_hash_bits;
+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)
+{
+	netdev_put(nhc->nhc_dev, &nhc->nhc_dev_tracker);
+	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)
+		atomic_dec(&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\n", fi);
+		return;
+	}
+
+	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 && refcount_dec_and_test(&fi->fib_treeref)) {
+		hlist_del(&fi->fib_hash);
+
+		/* Paired with READ_ONCE() in fib_create_info(). */
+		WRITE_ONCE(fib_info_cnt, fib_info_cnt - 1);
+
+		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)
+		}
+		/* Paired with READ_ONCE() from fib_table_lookup() */
+		WRITE_ONCE(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)
+{
+	return hash_32(val, DEVINDEX_HASHBITS);
+}
+
+static struct hlist_head *
+fib_info_devhash_bucket(const struct net_device *dev)
+{
+	u32 val = net_hash_mix(dev_net(dev)) ^ dev->ifindex;
+
+	return &fib_info_devhash[fib_devindex_hashfn(val)];
+}
+
+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 &&
+		    nfi->fib_tb_id == fi->fib_tb_id &&
+		    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;
+
+	spin_lock(&fib_info_lock);
+
+	head = fib_info_devhash_bucket(dev);
+
+	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;
+}
+
+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.dscp = fa->fa_dscp;
+	fri.type = fa->fa_type;
+	fri.offload = READ_ONCE(fa->offload);
+	fri.trap = READ_ONCE(fa->trap);
+	fri.offload_failed = READ_ONCE(fa->offload_failed);
+	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 = READ_ONCE(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)
+		atomic_inc(&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;
+}
+
+static int fib_gw_from_attr(__be32 *gw, struct nlattr *nla,
+			    struct netlink_ext_ack *extack)
+{
+	if (nla_len(nla) < sizeof(*gw)) {
+		NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_GATEWAY");
+		return -EINVAL;
+	}
+
+	*gw = nla_get_in_addr(nla);
+
+	return 0;
+}
+
+/* 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) {
+				ret = fib_gw_from_attr(&fib_cfg.fc_gw4, nla,
+						       extack);
+				if (ret)
+					goto errout;
+
+				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) {
+				if (nla_len(nla) < sizeof(u32)) {
+					NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
+					return -EINVAL;
+				}
+				fib_cfg.fc_flow = nla_get_u32(nla);
+			}
+
+			fib_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);
+			/* RTA_ENCAP_TYPE length checked in
+			 * lwtunnel_valid_encap_type_attr
+			 */
+			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 (fi->nh) {
+		if (cfg->fc_oif || cfg->fc_gw_family || cfg->fc_mp)
+			return 1;
+		return 0;
+	}
+
+	if (cfg->fc_oif || cfg->fc_gw_family) {
+		struct fib_nh *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);
+			int err;
+
+			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) {
+				__be32 gw;
+
+				err = fib_gw_from_attr(&gw, nla, extack);
+				if (err)
+					return err;
+
+				if (nh->fib_nh_gw_family != AF_INET ||
+				    gw != nh->fib_nh_gw4)
+					return 1;
+			} else if (nlav) {
+				struct fib_config cfg2;
+
+				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) {
+				if (nla_len(nla) < sizeof(u32)) {
+					NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
+					return -EINVAL;
+				}
+				if (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;
+
+		type = array_index_nospec(type, RTAX_MAX + 1);
+		if (type == RTAX_CC_ALGO) {
+			char tmp[TCP_CA_NAME_MAX];
+			bool ecn_ca = false;
+
+			nla_strscpy(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;
+		netdev_hold(nh->fib_nh_dev, &nh->fib_nh_dev_tracker,
+			    GFP_KERNEL);
+		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;
+		netdev_hold(dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
+		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;
+	}
+	netdev_hold(dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
+	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;
+	netdev_hold(nh->fib_nh_dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
+	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 struct hlist_head *
+fib_info_laddrhash_bucket(const struct net *net, __be32 val)
+{
+	u32 slot = hash_32(net_hash_mix(net) ^ (__force u32)val,
+			   fib_info_hash_bits);
+
+	return &fib_info_laddrhash[slot];
+}
+
+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;
+
+	spin_lock_bh(&fib_info_lock);
+	old_info_hash = fib_info_hash;
+	old_laddrhash = fib_info_laddrhash;
+	fib_info_hash_size = new_size;
+	fib_info_hash_bits = ilog2(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;
+
+	fib_info_laddrhash = new_laddrhash;
+	for (i = 0; i < old_size; i++) {
+		struct hlist_head *lhead = &old_laddrhash[i];
+		struct hlist_node *n;
+		struct fib_info *fi;
+
+		hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
+			struct hlist_head *ldest;
+
+			ldest = fib_info_laddrhash_bucket(fi->fib_net,
+							  fi->fib_prefsrc);
+			hlist_add_head(&fi->fib_lhash, ldest);
+		}
+	}
+
+	spin_unlock_bh(&fib_info_lock);
+
+	kvfree(old_info_hash);
+	kvfree(old_laddrhash);
+}
+
+__be32 fib_info_update_nhc_saddr(struct net *net, struct fib_nh_common *nhc,
+				 unsigned char scope)
+{
+	struct fib_nh *nh;
+	__be32 saddr;
+
+	if (nhc->nhc_family != AF_INET)
+		return inet_select_addr(nhc->nhc_dev, 0, scope);
+
+	nh = container_of(nhc, struct fib_nh, nh_common);
+	saddr = inet_select_addr(nh->fib_nh_dev, nh->fib_nh_gw4, scope);
+
+	WRITE_ONCE(nh->nh_saddr, saddr);
+	WRITE_ONCE(nh->nh_saddr_genid, atomic_read(&net->ipv4.dev_addr_genid));
+
+	return 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 (READ_ONCE(nh->nh_saddr_genid) ==
+		    atomic_read(&net->ipv4.dev_addr_genid))
+			return READ_ONCE(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) {
+				refcount_inc(&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;
+
+	/* Paired with WRITE_ONCE() in fib_release_info() */
+	if (READ_ONCE(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;
+		size_t bytes;
+
+		if (!new_size)
+			new_size = 16;
+		bytes = (size_t)new_size * sizeof(struct hlist_head *);
+		new_info_hash = kvzalloc(bytes, GFP_KERNEL);
+		new_laddrhash = kvzalloc(bytes, GFP_KERNEL);
+		if (!new_info_hash || !new_laddrhash) {
+			kvfree(new_info_hash);
+			kvfree(new_laddrhash);
+		} 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);
+	}
+
+	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;
+		netdev_tracker_alloc(nh->fib_nh_dev, &nh->fib_nh_dev_tracker,
+				     GFP_KERNEL);
+	} 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) {
+		/* fib_table_lookup() should not see @fi yet. */
+		fi->fib_dead = 1;
+		free_fib_info(fi);
+		refcount_inc(&ofi->fib_treeref);
+		return ofi;
+	}
+
+	refcount_set(&fi->fib_treeref, 1);
+	refcount_set(&fi->fib_clntref, 1);
+	spin_lock_bh(&fib_info_lock);
+	fib_info_cnt++;
+	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_bucket(net, 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;
+
+			if (!nexthop_nh->fib_nh_dev)
+				continue;
+			head = fib_info_devhash_bucket(nexthop_nh->fib_nh_dev);
+			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) {
+		/* fib_table_lookup() should not see @fi yet. */
+		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) {
+			int alen = sizeof(struct in6_addr);
+			struct nlattr *nla;
+			struct rtvia *via;
+
+			nla = nla_reserve(skb, RTA_VIA, alen + 2);
+			if (!nla)
+				goto nla_put_failure;
+
+			via = nla_data(nla);
+			via->rtvia_family = AF_INET6;
+			memcpy(via->rtvia_addr, &nhc->nhc_gw.ipv6, alen);
+		} else if (nla_put_in6_addr(skb, RTA_GATEWAY,
+					    &nhc->nhc_gw.ipv6) < 0) {
+			goto nla_put_failure;
+		}
+		break;
+	}
+
+	*flags |= (nhc->nhc_flags &
+		   (RTNH_F_ONLINK | RTNH_F_OFFLOAD | RTNH_F_TRAP));
+
+	if (!skip_oif && nhc->nhc_dev &&
+	    nla_put_u32(skb, RTA_OIF, nhc->nhc_dev->ifindex))
+		goto nla_put_failure;
+
+	if (nhc->nhc_lwtstate &&
+	    lwtunnel_fill_encap(skb, nhc->nhc_lwtstate,
+				RTA_ENCAP, RTA_ENCAP_TYPE) < 0)
+		goto nla_put_failure;
+
+	return 0;
+
+nla_put_failure:
+	return -EMSGSIZE;
+}
+EXPORT_SYMBOL_GPL(fib_nexthop_info);
+
+#if IS_ENABLED(CONFIG_IP_ROUTE_MULTIPATH) || IS_ENABLED(CONFIG_IPV6)
+int fib_add_nexthop(struct sk_buff *skb, const struct fib_nh_common *nhc,
+		    int nh_weight, u8 rt_family, u32 nh_tclassid)
+{
+	const struct net_device *dev = nhc->nhc_dev;
+	struct rtnexthop *rtnh;
+	unsigned char flags = 0;
+
+	rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
+	if (!rtnh)
+		goto nla_put_failure;
+
+	rtnh->rtnh_hops = nh_weight - 1;
+	rtnh->rtnh_ifindex = dev ? dev->ifindex : 0;
+
+	if (fib_nexthop_info(skb, nhc, rt_family, &flags, true) < 0)
+		goto nla_put_failure;
+
+	rtnh->rtnh_flags = flags;
+
+	if (nh_tclassid && nla_put_u32(skb, RTA_FLOW, nh_tclassid))
+		goto nla_put_failure;
+
+	/* length of rtnetlink header + attributes */
+	rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *)rtnh;
+
+	return 0;
+
+nla_put_failure:
+	return -EMSGSIZE;
+}
+EXPORT_SYMBOL_GPL(fib_add_nexthop);
+#endif
+
+#ifdef CONFIG_IP_ROUTE_MULTIPATH
+static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
+{
+	struct nlattr *mp;
+
+	mp = nla_nest_start_noflag(skb, RTA_MULTIPATH);
+	if (!mp)
+		goto nla_put_failure;
+
+	if (unlikely(fi->nh)) {
+		if (nexthop_mpath_fill_node(skb, fi->nh, AF_INET) < 0)
+			goto nla_put_failure;
+		goto mp_end;
+	}
+
+	for_nexthops(fi) {
+		u32 nh_tclassid = 0;
+#ifdef CONFIG_IP_ROUTE_CLASSID
+		nh_tclassid = nh->nh_tclassid;
+#endif
+		if (fib_add_nexthop(skb, &nh->nh_common, nh->fib_nh_weight,
+				    AF_INET, nh_tclassid) < 0)
+			goto nla_put_failure;
+	} endfor_nexthops(fi);
+
+mp_end:
+	nla_nest_end(skb, mp);
+
+	return 0;
+
+nla_put_failure:
+	return -EMSGSIZE;
+}
+#else
+static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
+{
+	return 0;
+}
+#endif
+
+int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
+		  const struct fib_rt_info *fri, unsigned int flags)
+{
+	unsigned int nhs = fib_info_num_path(fri->fi);
+	struct fib_info *fi = fri->fi;
+	u32 tb_id = fri->tb_id;
+	struct nlmsghdr *nlh;
+	struct rtmsg *rtm;
+
+	nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
+	if (!nlh)
+		return -EMSGSIZE;
+
+	rtm = nlmsg_data(nlh);
+	rtm->rtm_family = AF_INET;
+	rtm->rtm_dst_len = fri->dst_len;
+	rtm->rtm_src_len = 0;
+	rtm->rtm_tos = inet_dscp_to_dsfield(fri->dscp);
+	if (tb_id < 256)
+		rtm->rtm_table = tb_id;
+	else
+		rtm->rtm_table = RT_TABLE_COMPAT;
+	if (nla_put_u32(skb, RTA_TABLE, tb_id))
+		goto nla_put_failure;
+	rtm->rtm_type = fri->type;
+	rtm->rtm_flags = fi->fib_flags;
+	rtm->rtm_scope = fi->fib_scope;
+	rtm->rtm_protocol = fi->fib_protocol;
+
+	if (rtm->rtm_dst_len &&
+	    nla_put_in_addr(skb, RTA_DST, fri->dst))
+		goto nla_put_failure;
+	if (fi->fib_priority &&
+	    nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
+		goto nla_put_failure;
+	if (rtnetlink_put_metrics(skb, fi->fib_metrics->metrics) < 0)
+		goto nla_put_failure;
+
+	if (fi->fib_prefsrc &&
+	    nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
+		goto nla_put_failure;
+
+	if (fi->nh) {
+		if (nla_put_u32(skb, RTA_NH_ID, fi->nh->id))
+			goto nla_put_failure;
+		if (nexthop_is_blackhole(fi->nh))
+			rtm->rtm_type = RTN_BLACKHOLE;
+		if (!READ_ONCE(fi->fib_net->ipv4.sysctl_nexthop_compat_mode))
+			goto offload;
+	}
+
+	if (nhs == 1) {
+		const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
+		unsigned char flags = 0;
+
+		if (fib_nexthop_info(skb, nhc, AF_INET, &flags, false) < 0)
+			goto nla_put_failure;
+
+		rtm->rtm_flags = flags;
+#ifdef CONFIG_IP_ROUTE_CLASSID
+		if (nhc->nhc_family == AF_INET) {
+			struct fib_nh *nh;
+
+			nh = container_of(nhc, struct fib_nh, nh_common);
+			if (nh->nh_tclassid &&
+			    nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
+				goto nla_put_failure;
+		}
+#endif
+	} else {
+		if (fib_add_multipath(skb, fi) < 0)
+			goto nla_put_failure;
+	}
+
+offload:
+	if (fri->offload)
+		rtm->rtm_flags |= RTM_F_OFFLOAD;
+	if (fri->trap)
+		rtm->rtm_flags |= RTM_F_TRAP;
+	if (fri->offload_failed)
+		rtm->rtm_flags |= RTM_F_OFFLOAD_FAILED;
+
+	nlmsg_end(skb, nlh);
+	return 0;
+
+nla_put_failure:
+	nlmsg_cancel(skb, nlh);
+	return -EMSGSIZE;
+}
+
+/*
+ * Update FIB if:
+ * - local address disappeared -> we must delete all the entries
+ *   referring to it.
+ * - device went down -> we must shutdown all nexthops going via it.
+ */
+int fib_sync_down_addr(struct net_device *dev, __be32 local)
+{
+	int tb_id = l3mdev_fib_table(dev) ? : RT_TABLE_MAIN;
+	struct net *net = dev_net(dev);
+	struct hlist_head *head;
+	struct fib_info *fi;
+	int ret = 0;
+
+	if (!fib_info_laddrhash || local == 0)
+		return 0;
+
+	head = fib_info_laddrhash_bucket(net, local);
+	hlist_for_each_entry(fi, head, fib_lhash) {
+		if (!net_eq(fi->fib_net, net) ||
+		    fi->fib_tb_id != tb_id)
+			continue;
+		if (fi->fib_prefsrc == local) {
+			fi->fib_flags |= RTNH_F_DEAD;
+			fi->pfsrc_removed = true;
+			ret++;
+		}
+	}
+	return ret;
+}
+
+static int call_fib_nh_notifiers(struct fib_nh *nh,
+				 enum fib_event_type event_type)
+{
+	bool ignore_link_down = ip_ignore_linkdown(nh->fib_nh_dev);
+	struct fib_nh_notifier_info info = {
+		.fib_nh = nh,
+	};
+
+	switch (event_type) {
+	case FIB_EVENT_NH_ADD:
+		if (nh->fib_nh_flags & RTNH_F_DEAD)
+			break;
+		if (ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN)
+			break;
+		return call_fib4_notifiers(dev_net(nh->fib_nh_dev), event_type,
+					   &info.info);
+	case FIB_EVENT_NH_DEL:
+		if ((ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN) ||
+		    (nh->fib_nh_flags & RTNH_F_DEAD))
+			return call_fib4_notifiers(dev_net(nh->fib_nh_dev),
+						   event_type, &info.info);
+		break;
+	default:
+		break;
+	}
+
+	return NOTIFY_DONE;
+}
+
+/* Update the PMTU of exceptions when:
+ * - the new MTU of the first hop becomes smaller than the PMTU
+ * - the old MTU was the same as the PMTU, and it limited discovery of
+ *   larger MTUs on the path. With that limit raised, we can now
+ *   discover larger MTUs
+ * A special case is locked exceptions, for which the PMTU is smaller
+ * than the minimal accepted PMTU:
+ * - if the new MTU is greater than the PMTU, don't make any change
+ * - otherwise, unlock and set PMTU
+ */
+void fib_nhc_update_mtu(struct fib_nh_common *nhc, u32 new, u32 orig)
+{
+	struct fnhe_hash_bucket *bucket;
+	int i;
+
+	bucket = rcu_dereference_protected(nhc->nhc_exceptions, 1);
+	if (!bucket)
+		return;
+
+	for (i = 0; i < FNHE_HASH_SIZE; i++) {
+		struct fib_nh_exception *fnhe;
+
+		for (fnhe = rcu_dereference_protected(bucket[i].chain, 1);
+		     fnhe;
+		     fnhe = rcu_dereference_protected(fnhe->fnhe_next, 1)) {
+			if (fnhe->fnhe_mtu_locked) {
+				if (new <= fnhe->fnhe_pmtu) {
+					fnhe->fnhe_pmtu = new;
+					fnhe->fnhe_mtu_locked = false;
+				}
+			} else if (new < fnhe->fnhe_pmtu ||
+				   orig == fnhe->fnhe_pmtu) {
+				fnhe->fnhe_pmtu = new;
+			}
+		}
+	}
+}
+
+void fib_sync_mtu(struct net_device *dev, u32 orig_mtu)
+{
+	struct hlist_head *head = fib_info_devhash_bucket(dev);
+	struct fib_nh *nh;
+
+	hlist_for_each_entry(nh, head, nh_hash) {
+		if (nh->fib_nh_dev == dev)
+			fib_nhc_update_mtu(&nh->nh_common, dev->mtu, orig_mtu);
+	}
+}
+
+/* Event              force Flags           Description
+ * NETDEV_CHANGE      0     LINKDOWN        Carrier OFF, not for scope host
+ * NETDEV_DOWN        0     LINKDOWN|DEAD   Link down, not for scope host
+ * NETDEV_DOWN        1     LINKDOWN|DEAD   Last address removed
+ * NETDEV_UNREGISTER  1     LINKDOWN|DEAD   Device removed
+ *
+ * only used when fib_nh is built into fib_info
+ */
+int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
+{
+	struct hlist_head *head = fib_info_devhash_bucket(dev);
+	struct fib_info *prev_fi = NULL;
+	int scope = RT_SCOPE_NOWHERE;
+	struct fib_nh *nh;
+	int ret = 0;
+
+	if (force)
+		scope = -1;
+
+	hlist_for_each_entry(nh, head, nh_hash) {
+		struct fib_info *fi = nh->nh_parent;
+		int dead;
+
+		BUG_ON(!fi->fib_nhs);
+		if (nh->fib_nh_dev != dev || fi == prev_fi)
+			continue;
+		prev_fi = fi;
+		dead = 0;
+		change_nexthops(fi) {
+			if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD)
+				dead++;
+			else if (nexthop_nh->fib_nh_dev == dev &&
+				 nexthop_nh->fib_nh_scope != scope) {
+				switch (event) {
+				case NETDEV_DOWN:
+				case NETDEV_UNREGISTER:
+					nexthop_nh->fib_nh_flags |= RTNH_F_DEAD;
+					fallthrough;
+				case NETDEV_CHANGE:
+					nexthop_nh->fib_nh_flags |= RTNH_F_LINKDOWN;
+					break;
+				}
+				call_fib_nh_notifiers(nexthop_nh,
+						      FIB_EVENT_NH_DEL);
+				dead++;
+			}
+#ifdef CONFIG_IP_ROUTE_MULTIPATH
+			if (event == NETDEV_UNREGISTER &&
+			    nexthop_nh->fib_nh_dev == dev) {
+				dead = fi->fib_nhs;
+				break;
+			}
+#endif
+		} endfor_nexthops(fi)
+		if (dead == fi->fib_nhs) {
+			switch (event) {
+			case NETDEV_DOWN:
+			case NETDEV_UNREGISTER:
+				fi->fib_flags |= RTNH_F_DEAD;
+				fallthrough;
+			case NETDEV_CHANGE:
+				fi->fib_flags |= RTNH_F_LINKDOWN;
+				break;
+			}
+			ret++;
+		}
+
+		fib_rebalance(fi);
+	}
+
+	return ret;
+}
+
+/* Must be invoked inside of an RCU protected region.  */
+static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
+{
+	struct fib_info *fi = NULL, *last_resort = NULL;
+	struct hlist_head *fa_head = res->fa_head;
+	struct fib_table *tb = res->table;
+	u8 slen = 32 - res->prefixlen;
+	int order = -1, last_idx = -1;
+	struct fib_alias *fa, *fa1 = NULL;
+	u32 last_prio = res->fi->fib_priority;
+	dscp_t last_dscp = 0;
+
+	hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
+		struct fib_info *next_fi = fa->fa_info;
+		struct fib_nh_common *nhc;
+
+		if (fa->fa_slen != slen)
+			continue;
+		if (fa->fa_dscp &&
+		    fa->fa_dscp != inet_dsfield_to_dscp(flp->flowi4_tos))
+			continue;
+		if (fa->tb_id != tb->tb_id)
+			continue;
+		if (next_fi->fib_priority > last_prio &&
+		    fa->fa_dscp == last_dscp) {
+			if (last_dscp)
+				continue;
+			break;
+		}
+		if (next_fi->fib_flags & RTNH_F_DEAD)
+			continue;
+		last_dscp = fa->fa_dscp;
+		last_prio = next_fi->fib_priority;
+
+		if (next_fi->fib_scope != res->scope ||
+		    fa->fa_type != RTN_UNICAST)
+			continue;
+
+		nhc = fib_info_nhc(next_fi, 0);
+		if (!nhc->nhc_gw_family || nhc->nhc_scope != RT_SCOPE_LINK)
+			continue;
+
+		fib_alias_accessed(fa);
+
+		if (!fi) {
+			if (next_fi != res->fi)
+				break;
+			fa1 = fa;
+		} else if (!fib_detect_death(fi, order, &last_resort,
+					     &last_idx, fa1->fa_default)) {
+			fib_result_assign(res, fi);
+			fa1->fa_default = order;
+			goto out;
+		}
+		fi = next_fi;
+		order++;
+	}
+
+	if (order <= 0 || !fi) {
+		if (fa1)
+			fa1->fa_default = -1;
+		goto out;
+	}
+
+	if (!fib_detect_death(fi, order, &last_resort, &last_idx,
+			      fa1->fa_default)) {
+		fib_result_assign(res, fi);
+		fa1->fa_default = order;
+		goto out;
+	}
+
+	if (last_idx >= 0)
+		fib_result_assign(res, last_resort);
+	fa1->fa_default = last_idx;
+out:
+	return;
+}
+
+/*
+ * Dead device goes up. We wake up dead nexthops.
+ * It takes sense only on multipath routes.
+ *
+ * only used when fib_nh is built into fib_info
+ */
+int fib_sync_up(struct net_device *dev, unsigned char nh_flags)
+{
+	struct fib_info *prev_fi;
+	struct hlist_head *head;
+	struct fib_nh *nh;
+	int ret;
+
+	if (!(dev->flags & IFF_UP))
+		return 0;
+
+	if (nh_flags & RTNH_F_DEAD) {
+		unsigned int flags = dev_get_flags(dev);
+
+		if (flags & (IFF_RUNNING | IFF_LOWER_UP))
+			nh_flags |= RTNH_F_LINKDOWN;
+	}
+
+	prev_fi = NULL;
+	head = fib_info_devhash_bucket(dev);
+	ret = 0;
+
+	hlist_for_each_entry(nh, head, nh_hash) {
+		struct fib_info *fi = nh->nh_parent;
+		int alive;
+
+		BUG_ON(!fi->fib_nhs);
+		if (nh->fib_nh_dev != dev || fi == prev_fi)
+			continue;
+
+		prev_fi = fi;
+		alive = 0;
+		change_nexthops(fi) {
+			if (!(nexthop_nh->fib_nh_flags & nh_flags)) {
+				alive++;
+				continue;
+			}
+			if (!nexthop_nh->fib_nh_dev ||
+			    !(nexthop_nh->fib_nh_dev->flags & IFF_UP))
+				continue;
+			if (nexthop_nh->fib_nh_dev != dev ||
+			    !__in_dev_get_rtnl(dev))
+				continue;
+			alive++;
+			nexthop_nh->fib_nh_flags &= ~nh_flags;
+			call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
+		} endfor_nexthops(fi)
+
+		if (alive > 0) {
+			fi->fib_flags &= ~nh_flags;
+			ret++;
+		}
+
+		fib_rebalance(fi);
+	}
+
+	return ret;
+}
+
+#ifdef CONFIG_IP_ROUTE_MULTIPATH
+static bool fib_good_nh(const struct fib_nh *nh)
+{
+	int state = NUD_REACHABLE;
+
+	if (nh->fib_nh_scope == RT_SCOPE_LINK) {
+		struct neighbour *n;
+
+		rcu_read_lock();
+
+		if (likely(nh->fib_nh_gw_family == AF_INET))
+			n = __ipv4_neigh_lookup_noref(nh->fib_nh_dev,
+						   (__force u32)nh->fib_nh_gw4);
+		else if (nh->fib_nh_gw_family == AF_INET6)
+			n = __ipv6_neigh_lookup_noref_stub(nh->fib_nh_dev,
+							   &nh->fib_nh_gw6);
+		else
+			n = NULL;
+		if (n)
+			state = READ_ONCE(n->nud_state);
+
+		rcu_read_unlock();
+	}
+
+	return !!(state & NUD_VALID);
+}
+
+void fib_select_multipath(struct fib_result *res, int hash)
+{
+	struct fib_info *fi = res->fi;
+	struct net *net = fi->fib_net;
+	bool first = false;
+
+	if (unlikely(res->fi->nh)) {
+		nexthop_path_fib_result(res, hash);
+		return;
+	}
+
+	change_nexthops(fi) {
+		if (READ_ONCE(net->ipv4.sysctl_fib_multipath_use_neigh)) {
+			if (!fib_good_nh(nexthop_nh))
+				continue;
+			if (!first) {
+				res->nh_sel = nhsel;
+				res->nhc = &nexthop_nh->nh_common;
+				first = true;
+			}
+		}
+
+		if (hash > atomic_read(&nexthop_nh->fib_nh_upper_bound))
+			continue;
+
+		res->nh_sel = nhsel;
+		res->nhc = &nexthop_nh->nh_common;
+		return;
+	} endfor_nexthops(fi);
+}
+#endif
+
+void fib_select_path(struct net *net, struct fib_result *res,
+		     struct flowi4 *fl4, const struct sk_buff *skb)
+{
+	if (fl4->flowi4_oif)
+		goto check_saddr;
+
+#ifdef CONFIG_IP_ROUTE_MULTIPATH
+	if (fib_info_num_path(res->fi) > 1) {
+		int h = fib_multipath_hash(net, fl4, skb, NULL);
+
+		fib_select_multipath(res, h);
+	}
+	else
+#endif
+	if (!res->prefixlen &&
+	    res->table->tb_num_default > 1 &&
+	    res->type == RTN_UNICAST)
+		fib_select_default(fl4, res);
+
+check_saddr:
+	if (!fl4->saddr)
+		fl4->saddr = fib_result_prefsrc(net, res);
+}