Adding upstream version 4.19.249.upstream/4.19.249upstream

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

1 files changed, 3299 insertions, 0 deletions

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
new file mode 100644
index 000000000..d7f17581d
--- /dev/null
+++ b/net/ipv4/route.c
@@ -0,0 +1,3299 @@
+/*
+ * 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.
+ *
+ *		ROUTE - implementation of the IP router.
+ *
+ * Authors:	Ross Biro
+ *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
+ *		Alan Cox, <gw4pts@gw4pts.ampr.org>
+ *		Linus Torvalds, <Linus.Torvalds@helsinki.fi>
+ *		Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
+ *
+ * Fixes:
+ *		Alan Cox	:	Verify area fixes.
+ *		Alan Cox	:	cli() protects routing changes
+ *		Rui Oliveira	:	ICMP routing table updates
+ *		(rco@di.uminho.pt)	Routing table insertion and update
+ *		Linus Torvalds	:	Rewrote bits to be sensible
+ *		Alan Cox	:	Added BSD route gw semantics
+ *		Alan Cox	:	Super /proc >4K
+ *		Alan Cox	:	MTU in route table
+ *		Alan Cox	: 	MSS actually. Also added the window
+ *					clamper.
+ *		Sam Lantinga	:	Fixed route matching in rt_del()
+ *		Alan Cox	:	Routing cache support.
+ *		Alan Cox	:	Removed compatibility cruft.
+ *		Alan Cox	:	RTF_REJECT support.
+ *		Alan Cox	:	TCP irtt support.
+ *		Jonathan Naylor	:	Added Metric support.
+ *	Miquel van Smoorenburg	:	BSD API fixes.
+ *	Miquel van Smoorenburg	:	Metrics.
+ *		Alan Cox	:	Use __u32 properly
+ *		Alan Cox	:	Aligned routing errors more closely with BSD
+ *					our system is still very different.
+ *		Alan Cox	:	Faster /proc handling
+ *	Alexey Kuznetsov	:	Massive rework to support tree based routing,
+ *					routing caches and better behaviour.
+ *
+ *		Olaf Erb	:	irtt wasn't being copied right.
+ *		Bjorn Ekwall	:	Kerneld route support.
+ *		Alan Cox	:	Multicast fixed (I hope)
+ * 		Pavel Krauz	:	Limited broadcast fixed
+ *		Mike McLagan	:	Routing by source
+ *	Alexey Kuznetsov	:	End of old history. Split to fib.c and
+ *					route.c and rewritten from scratch.
+ *		Andi Kleen	:	Load-limit warning messages.
+ *	Vitaly E. Lavrov	:	Transparent proxy revived after year coma.
+ *	Vitaly E. Lavrov	:	Race condition in ip_route_input_slow.
+ *	Tobias Ringstrom	:	Uninitialized res.type in ip_route_output_slow.
+ *	Vladimir V. Ivanov	:	IP rule info (flowid) is really useful.
+ *		Marc Boucher	:	routing by fwmark
+ *	Robert Olsson		:	Added rt_cache statistics
+ *	Arnaldo C. Melo		:	Convert proc stuff to seq_file
+ *	Eric Dumazet		:	hashed spinlocks and rt_check_expire() fixes.
+ * 	Ilia Sotnikov		:	Ignore TOS on PMTUD and Redirect
+ * 	Ilia Sotnikov		:	Removed TOS from hash calculations
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt) "IPv4: " fmt
+
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/bitops.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/bootmem.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/netdevice.h>
+#include <linux/proc_fs.h>
+#include <linux/init.h>
+#include <linux/skbuff.h>
+#include <linux/inetdevice.h>
+#include <linux/igmp.h>
+#include <linux/pkt_sched.h>
+#include <linux/mroute.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/random.h>
+#include <linux/rcupdate.h>
+#include <linux/times.h>
+#include <linux/slab.h>
+#include <linux/jhash.h>
+#include <net/dst.h>
+#include <net/dst_metadata.h>
+#include <net/net_namespace.h>
+#include <net/protocol.h>
+#include <net/ip.h>
+#include <net/route.h>
+#include <net/inetpeer.h>
+#include <net/sock.h>
+#include <net/ip_fib.h>
+#include <net/arp.h>
+#include <net/tcp.h>
+#include <net/icmp.h>
+#include <net/xfrm.h>
+#include <net/lwtunnel.h>
+#include <net/netevent.h>
+#include <net/rtnetlink.h>
+#ifdef CONFIG_SYSCTL
+#include <linux/sysctl.h>
+#endif
+#include <net/secure_seq.h>
+#include <net/ip_tunnels.h>
+#include <net/l3mdev.h>
+
+#include "fib_lookup.h"
+
+#define RT_FL_TOS(oldflp4) \
+	((oldflp4)->flowi4_tos & (IPTOS_RT_MASK | RTO_ONLINK))
+
+#define RT_GC_TIMEOUT (300*HZ)
+
+static int ip_rt_max_size;
+static int ip_rt_redirect_number __read_mostly	= 9;
+static int ip_rt_redirect_load __read_mostly	= HZ / 50;
+static int ip_rt_redirect_silence __read_mostly	= ((HZ / 50) << (9 + 1));
+static int ip_rt_error_cost __read_mostly	= HZ;
+static int ip_rt_error_burst __read_mostly	= 5 * HZ;
+static int ip_rt_mtu_expires __read_mostly	= 10 * 60 * HZ;
+static u32 ip_rt_min_pmtu __read_mostly		= 512 + 20 + 20;
+static int ip_rt_min_advmss __read_mostly	= 256;
+
+static int ip_rt_gc_timeout __read_mostly	= RT_GC_TIMEOUT;
+
+/*
+ *	Interface to generic destination cache.
+ */
+
+static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie);
+static unsigned int	 ipv4_default_advmss(const struct dst_entry *dst);
+static unsigned int	 ipv4_mtu(const struct dst_entry *dst);
+static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst);
+static void		 ipv4_link_failure(struct sk_buff *skb);
+static void		 ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
+					   struct sk_buff *skb, u32 mtu,
+					   bool confirm_neigh);
+static void		 ip_do_redirect(struct dst_entry *dst, struct sock *sk,
+					struct sk_buff *skb);
+static void		ipv4_dst_destroy(struct dst_entry *dst);
+
+static u32 *ipv4_cow_metrics(struct dst_entry *dst, unsigned long old)
+{
+	WARN_ON(1);
+	return NULL;
+}
+
+static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
+					   struct sk_buff *skb,
+					   const void *daddr);
+static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr);
+
+static struct dst_ops ipv4_dst_ops = {
+	.family =		AF_INET,
+	.check =		ipv4_dst_check,
+	.default_advmss =	ipv4_default_advmss,
+	.mtu =			ipv4_mtu,
+	.cow_metrics =		ipv4_cow_metrics,
+	.destroy =		ipv4_dst_destroy,
+	.negative_advice =	ipv4_negative_advice,
+	.link_failure =		ipv4_link_failure,
+	.update_pmtu =		ip_rt_update_pmtu,
+	.redirect =		ip_do_redirect,
+	.local_out =		__ip_local_out,
+	.neigh_lookup =		ipv4_neigh_lookup,
+	.confirm_neigh =	ipv4_confirm_neigh,
+};
+
+#define ECN_OR_COST(class)	TC_PRIO_##class
+
+const __u8 ip_tos2prio[16] = {
+	TC_PRIO_BESTEFFORT,
+	ECN_OR_COST(BESTEFFORT),
+	TC_PRIO_BESTEFFORT,
+	ECN_OR_COST(BESTEFFORT),
+	TC_PRIO_BULK,
+	ECN_OR_COST(BULK),
+	TC_PRIO_BULK,
+	ECN_OR_COST(BULK),
+	TC_PRIO_INTERACTIVE,
+	ECN_OR_COST(INTERACTIVE),
+	TC_PRIO_INTERACTIVE,
+	ECN_OR_COST(INTERACTIVE),
+	TC_PRIO_INTERACTIVE_BULK,
+	ECN_OR_COST(INTERACTIVE_BULK),
+	TC_PRIO_INTERACTIVE_BULK,
+	ECN_OR_COST(INTERACTIVE_BULK)
+};
+EXPORT_SYMBOL(ip_tos2prio);
+
+static DEFINE_PER_CPU(struct rt_cache_stat, rt_cache_stat);
+#define RT_CACHE_STAT_INC(field) raw_cpu_inc(rt_cache_stat.field)
+
+#ifdef CONFIG_PROC_FS
+static void *rt_cache_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	if (*pos)
+		return NULL;
+	return SEQ_START_TOKEN;
+}
+
+static void *rt_cache_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	++*pos;
+	return NULL;
+}
+
+static void rt_cache_seq_stop(struct seq_file *seq, void *v)
+{
+}
+
+static int rt_cache_seq_show(struct seq_file *seq, void *v)
+{
+	if (v == SEQ_START_TOKEN)
+		seq_printf(seq, "%-127s\n",
+			   "Iface\tDestination\tGateway \tFlags\t\tRefCnt\tUse\t"
+			   "Metric\tSource\t\tMTU\tWindow\tIRTT\tTOS\tHHRef\t"
+			   "HHUptod\tSpecDst");
+	return 0;
+}
+
+static const struct seq_operations rt_cache_seq_ops = {
+	.start  = rt_cache_seq_start,
+	.next   = rt_cache_seq_next,
+	.stop   = rt_cache_seq_stop,
+	.show   = rt_cache_seq_show,
+};
+
+static int rt_cache_seq_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &rt_cache_seq_ops);
+}
+
+static const struct file_operations rt_cache_seq_fops = {
+	.open	 = rt_cache_seq_open,
+	.read	 = seq_read,
+	.llseek	 = seq_lseek,
+	.release = seq_release,
+};
+
+
+static void *rt_cpu_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	int cpu;
+
+	if (*pos == 0)
+		return SEQ_START_TOKEN;
+
+	for (cpu = *pos-1; cpu < nr_cpu_ids; ++cpu) {
+		if (!cpu_possible(cpu))
+			continue;
+		*pos = cpu+1;
+		return &per_cpu(rt_cache_stat, cpu);
+	}
+	return NULL;
+}
+
+static void *rt_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	int cpu;
+
+	for (cpu = *pos; cpu < nr_cpu_ids; ++cpu) {
+		if (!cpu_possible(cpu))
+			continue;
+		*pos = cpu+1;
+		return &per_cpu(rt_cache_stat, cpu);
+	}
+	(*pos)++;
+	return NULL;
+
+}
+
+static void rt_cpu_seq_stop(struct seq_file *seq, void *v)
+{
+
+}
+
+static int rt_cpu_seq_show(struct seq_file *seq, void *v)
+{
+	struct rt_cache_stat *st = v;
+
+	if (v == SEQ_START_TOKEN) {
+		seq_printf(seq, "entries  in_hit in_slow_tot in_slow_mc in_no_route in_brd in_martian_dst in_martian_src  out_hit out_slow_tot out_slow_mc  gc_total gc_ignored gc_goal_miss gc_dst_overflow in_hlist_search out_hlist_search\n");
+		return 0;
+	}
+
+	seq_printf(seq,"%08x  %08x %08x %08x %08x %08x %08x %08x "
+		   " %08x %08x %08x %08x %08x %08x %08x %08x %08x \n",
+		   dst_entries_get_slow(&ipv4_dst_ops),
+		   0, /* st->in_hit */
+		   st->in_slow_tot,
+		   st->in_slow_mc,
+		   st->in_no_route,
+		   st->in_brd,
+		   st->in_martian_dst,
+		   st->in_martian_src,
+
+		   0, /* st->out_hit */
+		   st->out_slow_tot,
+		   st->out_slow_mc,
+
+		   0, /* st->gc_total */
+		   0, /* st->gc_ignored */
+		   0, /* st->gc_goal_miss */
+		   0, /* st->gc_dst_overflow */
+		   0, /* st->in_hlist_search */
+		   0  /* st->out_hlist_search */
+		);
+	return 0;
+}
+
+static const struct seq_operations rt_cpu_seq_ops = {
+	.start  = rt_cpu_seq_start,
+	.next   = rt_cpu_seq_next,
+	.stop   = rt_cpu_seq_stop,
+	.show   = rt_cpu_seq_show,
+};
+
+
+static int rt_cpu_seq_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &rt_cpu_seq_ops);
+}
+
+static const struct file_operations rt_cpu_seq_fops = {
+	.open	 = rt_cpu_seq_open,
+	.read	 = seq_read,
+	.llseek	 = seq_lseek,
+	.release = seq_release,
+};
+
+#ifdef CONFIG_IP_ROUTE_CLASSID
+static int rt_acct_proc_show(struct seq_file *m, void *v)
+{
+	struct ip_rt_acct *dst, *src;
+	unsigned int i, j;
+
+	dst = kcalloc(256, sizeof(struct ip_rt_acct), GFP_KERNEL);
+	if (!dst)
+		return -ENOMEM;
+
+	for_each_possible_cpu(i) {
+		src = (struct ip_rt_acct *)per_cpu_ptr(ip_rt_acct, i);
+		for (j = 0; j < 256; j++) {
+			dst[j].o_bytes   += src[j].o_bytes;
+			dst[j].o_packets += src[j].o_packets;
+			dst[j].i_bytes   += src[j].i_bytes;
+			dst[j].i_packets += src[j].i_packets;
+		}
+	}
+
+	seq_write(m, dst, 256 * sizeof(struct ip_rt_acct));
+	kfree(dst);
+	return 0;
+}
+#endif
+
+static int __net_init ip_rt_do_proc_init(struct net *net)
+{
+	struct proc_dir_entry *pde;
+
+	pde = proc_create("rt_cache", 0444, net->proc_net,
+			  &rt_cache_seq_fops);
+	if (!pde)
+		goto err1;
+
+	pde = proc_create("rt_cache", 0444,
+			  net->proc_net_stat, &rt_cpu_seq_fops);
+	if (!pde)
+		goto err2;
+
+#ifdef CONFIG_IP_ROUTE_CLASSID
+	pde = proc_create_single("rt_acct", 0, net->proc_net,
+			rt_acct_proc_show);
+	if (!pde)
+		goto err3;
+#endif
+	return 0;
+
+#ifdef CONFIG_IP_ROUTE_CLASSID
+err3:
+	remove_proc_entry("rt_cache", net->proc_net_stat);
+#endif
+err2:
+	remove_proc_entry("rt_cache", net->proc_net);
+err1:
+	return -ENOMEM;
+}
+
+static void __net_exit ip_rt_do_proc_exit(struct net *net)
+{
+	remove_proc_entry("rt_cache", net->proc_net_stat);
+	remove_proc_entry("rt_cache", net->proc_net);
+#ifdef CONFIG_IP_ROUTE_CLASSID
+	remove_proc_entry("rt_acct", net->proc_net);
+#endif
+}
+
+static struct pernet_operations ip_rt_proc_ops __net_initdata =  {
+	.init = ip_rt_do_proc_init,
+	.exit = ip_rt_do_proc_exit,
+};
+
+static int __init ip_rt_proc_init(void)
+{
+	return register_pernet_subsys(&ip_rt_proc_ops);
+}
+
+#else
+static inline int ip_rt_proc_init(void)
+{
+	return 0;
+}
+#endif /* CONFIG_PROC_FS */
+
+static inline bool rt_is_expired(const struct rtable *rth)
+{
+	return rth->rt_genid != rt_genid_ipv4(dev_net(rth->dst.dev));
+}
+
+void rt_cache_flush(struct net *net)
+{
+	rt_genid_bump_ipv4(net);
+}
+
+static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
+					   struct sk_buff *skb,
+					   const void *daddr)
+{
+	struct net_device *dev = dst->dev;
+	const __be32 *pkey = daddr;
+	const struct rtable *rt;
+	struct neighbour *n;
+
+	rt = (const struct rtable *) dst;
+	if (rt->rt_gateway)
+		pkey = (const __be32 *) &rt->rt_gateway;
+	else if (skb)
+		pkey = &ip_hdr(skb)->daddr;
+
+	n = __ipv4_neigh_lookup(dev, *(__force u32 *)pkey);
+	if (n)
+		return n;
+	return neigh_create(&arp_tbl, pkey, dev);
+}
+
+static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr)
+{
+	struct net_device *dev = dst->dev;
+	const __be32 *pkey = daddr;
+	const struct rtable *rt;
+
+	rt = (const struct rtable *)dst;
+	if (rt->rt_gateway)
+		pkey = (const __be32 *)&rt->rt_gateway;
+	else if (!daddr ||
+		 (rt->rt_flags &
+		  (RTCF_MULTICAST | RTCF_BROADCAST | RTCF_LOCAL)))
+		return;
+
+	__ipv4_confirm_neigh(dev, *(__force u32 *)pkey);
+}
+
+/* Hash tables of size 2048..262144 depending on RAM size.
+ * Each bucket uses 8 bytes.
+ */
+static u32 ip_idents_mask __read_mostly;
+static atomic_t *ip_idents __read_mostly;
+static u32 *ip_tstamps __read_mostly;
+
+/* In order to protect privacy, we add a perturbation to identifiers
+ * if one generator is seldom used. This makes hard for an attacker
+ * to infer how many packets were sent between two points in time.
+ */
+u32 ip_idents_reserve(u32 hash, int segs)
+{
+	u32 bucket, old, now = (u32)jiffies;
+	atomic_t *p_id;
+	u32 *p_tstamp;
+	u32 delta = 0;
+
+	bucket = hash & ip_idents_mask;
+	p_tstamp = ip_tstamps + bucket;
+	p_id = ip_idents + bucket;
+	old = READ_ONCE(*p_tstamp);
+
+	if (old != now && cmpxchg(p_tstamp, old, now) == old)
+		delta = prandom_u32_max(now - old);
+
+	/* If UBSAN reports an error there, please make sure your compiler
+	 * supports -fno-strict-overflow before reporting it that was a bug
+	 * in UBSAN, and it has been fixed in GCC-8.
+	 */
+	return atomic_add_return(segs + delta, p_id) - segs;
+}
+EXPORT_SYMBOL(ip_idents_reserve);
+
+void __ip_select_ident(struct net *net, struct iphdr *iph, int segs)
+{
+	u32 hash, id;
+
+	/* Note the following code is not safe, but this is okay. */
+	if (unlikely(siphash_key_is_zero(&net->ipv4.ip_id_key)))
+		get_random_bytes(&net->ipv4.ip_id_key,
+				 sizeof(net->ipv4.ip_id_key));
+
+	hash = siphash_3u32((__force u32)iph->daddr,
+			    (__force u32)iph->saddr,
+			    iph->protocol,
+			    &net->ipv4.ip_id_key);
+	id = ip_idents_reserve(hash, segs);
+	iph->id = htons(id);
+}
+EXPORT_SYMBOL(__ip_select_ident);
+
+static void __build_flow_key(const struct net *net, struct flowi4 *fl4,
+			     const struct sock *sk,
+			     const struct iphdr *iph,
+			     int oif, u8 tos,
+			     u8 prot, u32 mark, int flow_flags)
+{
+	if (sk) {
+		const struct inet_sock *inet = inet_sk(sk);
+
+		oif = sk->sk_bound_dev_if;
+		mark = sk->sk_mark;
+		tos = RT_CONN_FLAGS(sk);
+		prot = inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol;
+	}
+	flowi4_init_output(fl4, oif, mark, tos,
+			   RT_SCOPE_UNIVERSE, prot,
+			   flow_flags,
+			   iph->daddr, iph->saddr, 0, 0,
+			   sock_net_uid(net, sk));
+}
+
+static void build_skb_flow_key(struct flowi4 *fl4, const struct sk_buff *skb,
+			       const struct sock *sk)
+{
+	const struct net *net = dev_net(skb->dev);
+	const struct iphdr *iph = ip_hdr(skb);
+	int oif = skb->dev->ifindex;
+	u8 tos = RT_TOS(iph->tos);
+	u8 prot = iph->protocol;
+	u32 mark = skb->mark;
+
+	__build_flow_key(net, fl4, sk, iph, oif, tos, prot, mark, 0);
+}
+
+static void build_sk_flow_key(struct flowi4 *fl4, const struct sock *sk)
+{
+	const struct inet_sock *inet = inet_sk(sk);
+	const struct ip_options_rcu *inet_opt;
+	__be32 daddr = inet->inet_daddr;
+
+	rcu_read_lock();
+	inet_opt = rcu_dereference(inet->inet_opt);
+	if (inet_opt && inet_opt->opt.srr)
+		daddr = inet_opt->opt.faddr;
+	flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark,
+			   RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
+			   inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol,
+			   inet_sk_flowi_flags(sk),
+			   daddr, inet->inet_saddr, 0, 0, sk->sk_uid);
+	rcu_read_unlock();
+}
+
+static void ip_rt_build_flow_key(struct flowi4 *fl4, const struct sock *sk,
+				 const struct sk_buff *skb)
+{
+	if (skb)
+		build_skb_flow_key(fl4, skb, sk);
+	else
+		build_sk_flow_key(fl4, sk);
+}
+
+static DEFINE_SPINLOCK(fnhe_lock);
+
+static void fnhe_flush_routes(struct fib_nh_exception *fnhe)
+{
+	struct rtable *rt;
+
+	rt = rcu_dereference(fnhe->fnhe_rth_input);
+	if (rt) {
+		RCU_INIT_POINTER(fnhe->fnhe_rth_input, NULL);
+		dst_dev_put(&rt->dst);
+		dst_release(&rt->dst);
+	}
+	rt = rcu_dereference(fnhe->fnhe_rth_output);
+	if (rt) {
+		RCU_INIT_POINTER(fnhe->fnhe_rth_output, NULL);
+		dst_dev_put(&rt->dst);
+		dst_release(&rt->dst);
+	}
+}
+
+static void fnhe_remove_oldest(struct fnhe_hash_bucket *hash)
+{
+	struct fib_nh_exception __rcu **fnhe_p, **oldest_p;
+	struct fib_nh_exception *fnhe, *oldest = NULL;
+
+	for (fnhe_p = &hash->chain; ; fnhe_p = &fnhe->fnhe_next) {
+		fnhe = rcu_dereference_protected(*fnhe_p,
+						 lockdep_is_held(&fnhe_lock));
+		if (!fnhe)
+			break;
+		if (!oldest ||
+		    time_before(fnhe->fnhe_stamp, oldest->fnhe_stamp)) {
+			oldest = fnhe;
+			oldest_p = fnhe_p;
+		}
+	}
+	fnhe_flush_routes(oldest);
+	*oldest_p = oldest->fnhe_next;
+	kfree_rcu(oldest, rcu);
+}
+
+static u32 fnhe_hashfun(__be32 daddr)
+{
+	static siphash_key_t fnhe_hash_key __read_mostly;
+	u64 hval;
+
+	net_get_random_once(&fnhe_hash_key, sizeof(fnhe_hash_key));
+	hval = siphash_1u32((__force u32)daddr, &fnhe_hash_key);
+	return hash_64(hval, FNHE_HASH_SHIFT);
+}
+
+static void fill_route_from_fnhe(struct rtable *rt, struct fib_nh_exception *fnhe)
+{
+	rt->rt_pmtu = fnhe->fnhe_pmtu;
+	rt->rt_mtu_locked = fnhe->fnhe_mtu_locked;
+	rt->dst.expires = fnhe->fnhe_expires;
+
+	if (fnhe->fnhe_gw) {
+		rt->rt_flags |= RTCF_REDIRECTED;
+		rt->rt_gateway = fnhe->fnhe_gw;
+		rt->rt_uses_gateway = 1;
+	}
+}
+
+static void update_or_create_fnhe(struct fib_nh *nh, __be32 daddr, __be32 gw,
+				  u32 pmtu, bool lock, unsigned long expires)
+{
+	struct fnhe_hash_bucket *hash;
+	struct fib_nh_exception *fnhe;
+	struct rtable *rt;
+	u32 genid, hval;
+	unsigned int i;
+	int depth;
+
+	genid = fnhe_genid(dev_net(nh->nh_dev));
+	hval = fnhe_hashfun(daddr);
+
+	spin_lock_bh(&fnhe_lock);
+
+	hash = rcu_dereference(nh->nh_exceptions);
+	if (!hash) {
+		hash = kcalloc(FNHE_HASH_SIZE, sizeof(*hash), GFP_ATOMIC);
+		if (!hash)
+			goto out_unlock;
+		rcu_assign_pointer(nh->nh_exceptions, hash);
+	}
+
+	hash += hval;
+
+	depth = 0;
+	for (fnhe = rcu_dereference(hash->chain); fnhe;
+	     fnhe = rcu_dereference(fnhe->fnhe_next)) {
+		if (fnhe->fnhe_daddr == daddr)
+			break;
+		depth++;
+	}
+
+	if (fnhe) {
+		if (fnhe->fnhe_genid != genid)
+			fnhe->fnhe_genid = genid;
+		if (gw)
+			fnhe->fnhe_gw = gw;
+		if (pmtu) {
+			fnhe->fnhe_pmtu = pmtu;
+			fnhe->fnhe_mtu_locked = lock;
+		}
+		fnhe->fnhe_expires = max(1UL, expires);
+		/* Update all cached dsts too */
+		rt = rcu_dereference(fnhe->fnhe_rth_input);
+		if (rt)
+			fill_route_from_fnhe(rt, fnhe);
+		rt = rcu_dereference(fnhe->fnhe_rth_output);
+		if (rt)
+			fill_route_from_fnhe(rt, fnhe);
+	} else {
+		/* Randomize max depth to avoid some side channels attacks. */
+		int max_depth = FNHE_RECLAIM_DEPTH +
+				prandom_u32_max(FNHE_RECLAIM_DEPTH);
+
+		while (depth > max_depth) {
+			fnhe_remove_oldest(hash);
+			depth--;
+		}
+
+		fnhe = kzalloc(sizeof(*fnhe), GFP_ATOMIC);
+		if (!fnhe)
+			goto out_unlock;
+
+		fnhe->fnhe_next = hash->chain;
+
+		fnhe->fnhe_genid = genid;
+		fnhe->fnhe_daddr = daddr;
+		fnhe->fnhe_gw = gw;
+		fnhe->fnhe_pmtu = pmtu;
+		fnhe->fnhe_mtu_locked = lock;
+		fnhe->fnhe_expires = max(1UL, expires);
+
+		rcu_assign_pointer(hash->chain, fnhe);
+
+		/* Exception created; mark the cached routes for the nexthop
+		 * stale, so anyone caching it rechecks if this exception
+		 * applies to them.
+		 */
+		rt = rcu_dereference(nh->nh_rth_input);
+		if (rt)
+			rt->dst.obsolete = DST_OBSOLETE_KILL;
+
+		for_each_possible_cpu(i) {
+			struct rtable __rcu **prt;
+			prt = per_cpu_ptr(nh->nh_pcpu_rth_output, i);
+			rt = rcu_dereference(*prt);
+			if (rt)
+				rt->dst.obsolete = DST_OBSOLETE_KILL;
+		}
+	}
+
+	fnhe->fnhe_stamp = jiffies;
+
+out_unlock:
+	spin_unlock_bh(&fnhe_lock);
+}
+
+static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flowi4 *fl4,
+			     bool kill_route)
+{
+	__be32 new_gw = icmp_hdr(skb)->un.gateway;
+	__be32 old_gw = ip_hdr(skb)->saddr;
+	struct net_device *dev = skb->dev;
+	struct in_device *in_dev;
+	struct fib_result res;
+	struct neighbour *n;
+	struct net *net;
+
+	switch (icmp_hdr(skb)->code & 7) {
+	case ICMP_REDIR_NET:
+	case ICMP_REDIR_NETTOS:
+	case ICMP_REDIR_HOST:
+	case ICMP_REDIR_HOSTTOS:
+		break;
+
+	default:
+		return;
+	}
+
+	if (rt->rt_gateway != old_gw)
+		return;
+
+	in_dev = __in_dev_get_rcu(dev);
+	if (!in_dev)
+		return;
+
+	net = dev_net(dev);
+	if (new_gw == old_gw || !IN_DEV_RX_REDIRECTS(in_dev) ||
+	    ipv4_is_multicast(new_gw) || ipv4_is_lbcast(new_gw) ||
+	    ipv4_is_zeronet(new_gw))
+		goto reject_redirect;
+
+	if (!IN_DEV_SHARED_MEDIA(in_dev)) {
+		if (!inet_addr_onlink(in_dev, new_gw, old_gw))
+			goto reject_redirect;
+		if (IN_DEV_SEC_REDIRECTS(in_dev) && ip_fib_check_default(new_gw, dev))
+			goto reject_redirect;
+	} else {
+		if (inet_addr_type(net, new_gw) != RTN_UNICAST)
+			goto reject_redirect;
+	}
+
+	n = __ipv4_neigh_lookup(rt->dst.dev, new_gw);
+	if (!n)
+		n = neigh_create(&arp_tbl, &new_gw, rt->dst.dev);
+	if (!IS_ERR(n)) {
+		if (!(n->nud_state & NUD_VALID)) {
+			neigh_event_send(n, NULL);
+		} else {
+			if (fib_lookup(net, fl4, &res, 0) == 0) {
+				struct fib_nh *nh;
+
+				fib_select_path(net, &res, fl4, skb);
+				nh = &FIB_RES_NH(res);
+				update_or_create_fnhe(nh, fl4->daddr, new_gw,
+						0, false,
+						jiffies + ip_rt_gc_timeout);
+			}
+			if (kill_route)
+				rt->dst.obsolete = DST_OBSOLETE_KILL;
+			call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, n);
+		}
+		neigh_release(n);
+	}
+	return;
+
+reject_redirect:
+#ifdef CONFIG_IP_ROUTE_VERBOSE
+	if (IN_DEV_LOG_MARTIANS(in_dev)) {
+		const struct iphdr *iph = (const struct iphdr *) skb->data;
+		__be32 daddr = iph->daddr;
+		__be32 saddr = iph->saddr;
+
+		net_info_ratelimited("Redirect from %pI4 on %s about %pI4 ignored\n"
+				     "  Advised path = %pI4 -> %pI4\n",
+				     &old_gw, dev->name, &new_gw,
+				     &saddr, &daddr);
+	}
+#endif
+	;
+}
+
+static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb)
+{
+	struct rtable *rt;
+	struct flowi4 fl4;
+	const struct iphdr *iph = (const struct iphdr *) skb->data;
+	struct net *net = dev_net(skb->dev);
+	int oif = skb->dev->ifindex;
+	u8 tos = RT_TOS(iph->tos);
+	u8 prot = iph->protocol;
+	u32 mark = skb->mark;
+
+	rt = (struct rtable *) dst;
+
+	__build_flow_key(net, &fl4, sk, iph, oif, tos, prot, mark, 0);
+	__ip_do_redirect(rt, skb, &fl4, true);
+}
+
+static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)
+{
+	struct rtable *rt = (struct rtable *)dst;
+	struct dst_entry *ret = dst;
+
+	if (rt) {
+		if (dst->obsolete > 0) {
+			ip_rt_put(rt);
+			ret = NULL;
+		} else if ((rt->rt_flags & RTCF_REDIRECTED) ||
+			   rt->dst.expires) {
+			ip_rt_put(rt);
+			ret = NULL;
+		}
+	}
+	return ret;
+}
+
+/*
+ * Algorithm:
+ *	1. The first ip_rt_redirect_number redirects are sent
+ *	   with exponential backoff, then we stop sending them at all,
+ *	   assuming that the host ignores our redirects.
+ *	2. If we did not see packets requiring redirects
+ *	   during ip_rt_redirect_silence, we assume that the host
+ *	   forgot redirected route and start to send redirects again.
+ *
+ * This algorithm is much cheaper and more intelligent than dumb load limiting
+ * in icmp.c.
+ *
+ * NOTE. Do not forget to inhibit load limiting for redirects (redundant)
+ * and "frag. need" (breaks PMTU discovery) in icmp.c.
+ */
+
+void ip_rt_send_redirect(struct sk_buff *skb)
+{
+	struct rtable *rt = skb_rtable(skb);
+	struct in_device *in_dev;
+	struct inet_peer *peer;
+	struct net *net;
+	int log_martians;
+	int vif;
+
+	rcu_read_lock();
+	in_dev = __in_dev_get_rcu(rt->dst.dev);
+	if (!in_dev || !IN_DEV_TX_REDIRECTS(in_dev)) {
+		rcu_read_unlock();
+		return;
+	}
+	log_martians = IN_DEV_LOG_MARTIANS(in_dev);
+	vif = l3mdev_master_ifindex_rcu(rt->dst.dev);
+	rcu_read_unlock();
+
+	net = dev_net(rt->dst.dev);
+	peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr, vif, 1);
+	if (!peer) {
+		icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST,
+			  rt_nexthop(rt, ip_hdr(skb)->daddr));
+		return;
+	}
+
+	/* No redirected packets during ip_rt_redirect_silence;
+	 * reset the algorithm.
+	 */
+	if (time_after(jiffies, peer->rate_last + ip_rt_redirect_silence)) {
+		peer->rate_tokens = 0;
+		peer->n_redirects = 0;
+	}
+
+	/* Too many ignored redirects; do not send anything
+	 * set dst.rate_last to the last seen redirected packet.
+	 */
+	if (peer->n_redirects >= ip_rt_redirect_number) {
+		peer->rate_last = jiffies;
+		goto out_put_peer;
+	}
+
+	/* Check for load limit; set rate_last to the latest sent
+	 * redirect.
+	 */
+	if (peer->n_redirects == 0 ||
+	    time_after(jiffies,
+		       (peer->rate_last +
+			(ip_rt_redirect_load << peer->n_redirects)))) {
+		__be32 gw = rt_nexthop(rt, ip_hdr(skb)->daddr);
+
+		icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST, gw);
+		peer->rate_last = jiffies;
+		++peer->n_redirects;
+#ifdef CONFIG_IP_ROUTE_VERBOSE
+		if (log_martians &&
+		    peer->n_redirects == ip_rt_redirect_number)
+			net_warn_ratelimited("host %pI4/if%d ignores redirects for %pI4 to %pI4\n",
+					     &ip_hdr(skb)->saddr, inet_iif(skb),
+					     &ip_hdr(skb)->daddr, &gw);
+#endif
+	}
+out_put_peer:
+	inet_putpeer(peer);
+}
+
+static int ip_error(struct sk_buff *skb)
+{
+	struct rtable *rt = skb_rtable(skb);
+	struct net_device *dev = skb->dev;
+	struct in_device *in_dev;
+	struct inet_peer *peer;
+	unsigned long now;
+	struct net *net;
+	bool send;
+	int code;
+
+	if (netif_is_l3_master(skb->dev)) {
+		dev = __dev_get_by_index(dev_net(skb->dev), IPCB(skb)->iif);
+		if (!dev)
+			goto out;
+	}
+
+	in_dev = __in_dev_get_rcu(dev);
+
+	/* IP on this device is disabled. */
+	if (!in_dev)
+		goto out;
+
+	net = dev_net(rt->dst.dev);
+	if (!IN_DEV_FORWARD(in_dev)) {
+		switch (rt->dst.error) {
+		case EHOSTUNREACH:
+			__IP_INC_STATS(net, IPSTATS_MIB_INADDRERRORS);
+			break;
+
+		case ENETUNREACH:
+			__IP_INC_STATS(net, IPSTATS_MIB_INNOROUTES);
+			break;
+		}
+		goto out;
+	}
+
+	switch (rt->dst.error) {
+	case EINVAL:
+	default:
+		goto out;
+	case EHOSTUNREACH:
+		code = ICMP_HOST_UNREACH;
+		break;
+	case ENETUNREACH:
+		code = ICMP_NET_UNREACH;
+		__IP_INC_STATS(net, IPSTATS_MIB_INNOROUTES);
+		break;
+	case EACCES:
+		code = ICMP_PKT_FILTERED;
+		break;
+	}
+
+	peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr,
+			       l3mdev_master_ifindex(skb->dev), 1);
+
+	send = true;
+	if (peer) {
+		now = jiffies;
+		peer->rate_tokens += now - peer->rate_last;
+		if (peer->rate_tokens > ip_rt_error_burst)
+			peer->rate_tokens = ip_rt_error_burst;
+		peer->rate_last = now;
+		if (peer->rate_tokens >= ip_rt_error_cost)
+			peer->rate_tokens -= ip_rt_error_cost;
+		else
+			send = false;
+		inet_putpeer(peer);
+	}
+	if (send)
+		icmp_send(skb, ICMP_DEST_UNREACH, code, 0);
+
+out:	kfree_skb(skb);
+	return 0;
+}
+
+static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
+{
+	struct dst_entry *dst = &rt->dst;
+	struct net *net = dev_net(dst->dev);
+	u32 old_mtu = ipv4_mtu(dst);
+	struct fib_result res;
+	bool lock = false;
+
+	if (ip_mtu_locked(dst))
+		return;
+
+	if (old_mtu < mtu)
+		return;
+
+	if (mtu < ip_rt_min_pmtu) {
+		lock = true;
+		mtu = min(old_mtu, ip_rt_min_pmtu);
+	}
+
+	if (rt->rt_pmtu == mtu && !lock &&
+	    time_before(jiffies, dst->expires - ip_rt_mtu_expires / 2))
+		return;
+
+	rcu_read_lock();
+	if (fib_lookup(net, fl4, &res, 0) == 0) {
+		struct fib_nh *nh;
+
+		fib_select_path(net, &res, fl4, NULL);
+		nh = &FIB_RES_NH(res);
+		update_or_create_fnhe(nh, fl4->daddr, 0, mtu, lock,
+				      jiffies + ip_rt_mtu_expires);
+	}
+	rcu_read_unlock();
+}
+
+static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
+			      struct sk_buff *skb, u32 mtu,
+			      bool confirm_neigh)
+{
+	struct rtable *rt = (struct rtable *) dst;
+	struct flowi4 fl4;
+
+	ip_rt_build_flow_key(&fl4, sk, skb);
+	__ip_rt_update_pmtu(rt, &fl4, mtu);
+}
+
+void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu,
+		      int oif, u32 mark, u8 protocol, int flow_flags)
+{
+	const struct iphdr *iph = (const struct iphdr *) skb->data;
+	struct flowi4 fl4;
+	struct rtable *rt;
+
+	if (!mark)
+		mark = IP4_REPLY_MARK(net, skb->mark);
+
+	__build_flow_key(net, &fl4, NULL, iph, oif,
+			 RT_TOS(iph->tos), protocol, mark, flow_flags);
+	rt = __ip_route_output_key(net, &fl4);
+	if (!IS_ERR(rt)) {
+		__ip_rt_update_pmtu(rt, &fl4, mtu);
+		ip_rt_put(rt);
+	}
+}
+EXPORT_SYMBOL_GPL(ipv4_update_pmtu);
+
+static void __ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
+{
+	const struct iphdr *iph = (const struct iphdr *) skb->data;
+	struct flowi4 fl4;
+	struct rtable *rt;
+
+	__build_flow_key(sock_net(sk), &fl4, sk, iph, 0, 0, 0, 0, 0);
+
+	if (!fl4.flowi4_mark)
+		fl4.flowi4_mark = IP4_REPLY_MARK(sock_net(sk), skb->mark);
+
+	rt = __ip_route_output_key(sock_net(sk), &fl4);
+	if (!IS_ERR(rt)) {
+		__ip_rt_update_pmtu(rt, &fl4, mtu);
+		ip_rt_put(rt);
+	}
+}
+
+void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
+{
+	const struct iphdr *iph = (const struct iphdr *) skb->data;
+	struct flowi4 fl4;
+	struct rtable *rt;
+	struct dst_entry *odst = NULL;
+	bool new = false;
+	struct net *net = sock_net(sk);
+
+	bh_lock_sock(sk);
+
+	if (!ip_sk_accept_pmtu(sk))
+		goto out;
+
+	odst = sk_dst_get(sk);
+
+	if (sock_owned_by_user(sk) || !odst) {
+		__ipv4_sk_update_pmtu(skb, sk, mtu);
+		goto out;
+	}
+
+	__build_flow_key(net, &fl4, sk, iph, 0, 0, 0, 0, 0);
+
+	rt = (struct rtable *)odst;
+	if (odst->obsolete && !odst->ops->check(odst, 0)) {
+		rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
+		if (IS_ERR(rt))
+			goto out;
+
+		new = true;
+	}
+
+	__ip_rt_update_pmtu((struct rtable *) xfrm_dst_path(&rt->dst), &fl4, mtu);
+
+	if (!dst_check(&rt->dst, 0)) {
+		if (new)
+			dst_release(&rt->dst);
+
+		rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
+		if (IS_ERR(rt))
+			goto out;
+
+		new = true;
+	}
+
+	if (new)
+		sk_dst_set(sk, &rt->dst);
+
+out:
+	bh_unlock_sock(sk);
+	dst_release(odst);
+}
+EXPORT_SYMBOL_GPL(ipv4_sk_update_pmtu);
+
+void ipv4_redirect(struct sk_buff *skb, struct net *net,
+		   int oif, u32 mark, u8 protocol, int flow_flags)
+{
+	const struct iphdr *iph = (const struct iphdr *) skb->data;
+	struct flowi4 fl4;
+	struct rtable *rt;
+
+	__build_flow_key(net, &fl4, NULL, iph, oif,
+			 RT_TOS(iph->tos), protocol, mark, flow_flags);
+	rt = __ip_route_output_key(net, &fl4);
+	if (!IS_ERR(rt)) {
+		__ip_do_redirect(rt, skb, &fl4, false);
+		ip_rt_put(rt);
+	}
+}
+EXPORT_SYMBOL_GPL(ipv4_redirect);
+
+void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk)
+{
+	const struct iphdr *iph = (const struct iphdr *) skb->data;
+	struct flowi4 fl4;
+	struct rtable *rt;
+	struct net *net = sock_net(sk);
+
+	__build_flow_key(net, &fl4, sk, iph, 0, 0, 0, 0, 0);
+	rt = __ip_route_output_key(net, &fl4);
+	if (!IS_ERR(rt)) {
+		__ip_do_redirect(rt, skb, &fl4, false);
+		ip_rt_put(rt);
+	}
+}
+EXPORT_SYMBOL_GPL(ipv4_sk_redirect);
+
+static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
+{
+	struct rtable *rt = (struct rtable *) dst;
+
+	/* All IPV4 dsts are created with ->obsolete set to the value
+	 * DST_OBSOLETE_FORCE_CHK which forces validation calls down
+	 * into this function always.
+	 *
+	 * When a PMTU/redirect information update invalidates a route,
+	 * this is indicated by setting obsolete to DST_OBSOLETE_KILL or
+	 * DST_OBSOLETE_DEAD by dst_free().
+	 */
+	if (dst->obsolete != DST_OBSOLETE_FORCE_CHK || rt_is_expired(rt))
+		return NULL;
+	return dst;
+}
+
+static void ipv4_send_dest_unreach(struct sk_buff *skb)
+{
+	struct ip_options opt;
+	int res;
+
+	/* Recompile ip options since IPCB may not be valid anymore.
+	 * Also check we have a reasonable ipv4 header.
+	 */
+	if (!pskb_network_may_pull(skb, sizeof(struct iphdr)) ||
+	    ip_hdr(skb)->version != 4 || ip_hdr(skb)->ihl < 5)
+		return;
+
+	memset(&opt, 0, sizeof(opt));
+	if (ip_hdr(skb)->ihl > 5) {
+		if (!pskb_network_may_pull(skb, ip_hdr(skb)->ihl * 4))
+			return;
+		opt.optlen = ip_hdr(skb)->ihl * 4 - sizeof(struct iphdr);
+
+		rcu_read_lock();
+		res = __ip_options_compile(dev_net(skb->dev), &opt, skb, NULL);
+		rcu_read_unlock();
+
+		if (res)
+			return;
+	}
+	__icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0, &opt);
+}
+
+static void ipv4_link_failure(struct sk_buff *skb)
+{
+	struct rtable *rt;
+
+	ipv4_send_dest_unreach(skb);
+
+	rt = skb_rtable(skb);
+	if (rt)
+		dst_set_expires(&rt->dst, 0);
+}
+
+static int ip_rt_bug(struct net *net, struct sock *sk, struct sk_buff *skb)
+{
+	pr_debug("%s: %pI4 -> %pI4, %s\n",
+		 __func__, &ip_hdr(skb)->saddr, &ip_hdr(skb)->daddr,
+		 skb->dev ? skb->dev->name : "?");
+	kfree_skb(skb);
+	WARN_ON(1);
+	return 0;
+}
+
+/*
+   We do not cache source address of outgoing interface,
+   because it is used only by IP RR, TS and SRR options,
+   so that it out of fast path.
+
+   BTW remember: "addr" is allowed to be not aligned
+   in IP options!
+ */
+
+void ip_rt_get_source(u8 *addr, struct sk_buff *skb, struct rtable *rt)
+{
+	__be32 src;
+
+	if (rt_is_output_route(rt))
+		src = ip_hdr(skb)->saddr;
+	else {
+		struct fib_result res;
+		struct flowi4 fl4;
+		struct iphdr *iph;
+
+		iph = ip_hdr(skb);
+
+		memset(&fl4, 0, sizeof(fl4));
+		fl4.daddr = iph->daddr;
+		fl4.saddr = iph->saddr;
+		fl4.flowi4_tos = RT_TOS(iph->tos);
+		fl4.flowi4_oif = rt->dst.dev->ifindex;
+		fl4.flowi4_iif = skb->dev->ifindex;
+		fl4.flowi4_mark = skb->mark;
+
+		rcu_read_lock();
+		if (fib_lookup(dev_net(rt->dst.dev), &fl4, &res, 0) == 0)
+			src = FIB_RES_PREFSRC(dev_net(rt->dst.dev), res);
+		else
+			src = inet_select_addr(rt->dst.dev,
+					       rt_nexthop(rt, iph->daddr),
+					       RT_SCOPE_UNIVERSE);
+		rcu_read_unlock();
+	}
+	memcpy(addr, &src, 4);
+}
+
+#ifdef CONFIG_IP_ROUTE_CLASSID
+static void set_class_tag(struct rtable *rt, u32 tag)
+{
+	if (!(rt->dst.tclassid & 0xFFFF))
+		rt->dst.tclassid |= tag & 0xFFFF;
+	if (!(rt->dst.tclassid & 0xFFFF0000))
+		rt->dst.tclassid |= tag & 0xFFFF0000;
+}
+#endif
+
+static unsigned int ipv4_default_advmss(const struct dst_entry *dst)
+{
+	unsigned int header_size = sizeof(struct tcphdr) + sizeof(struct iphdr);
+	unsigned int advmss = max_t(unsigned int, ipv4_mtu(dst) - header_size,
+				    ip_rt_min_advmss);
+
+	return min(advmss, IPV4_MAX_PMTU - header_size);
+}
+
+static unsigned int ipv4_mtu(const struct dst_entry *dst)
+{
+	const struct rtable *rt = (const struct rtable *) dst;
+	unsigned int mtu = rt->rt_pmtu;
+
+	if (!mtu || time_after_eq(jiffies, rt->dst.expires))
+		mtu = dst_metric_raw(dst, RTAX_MTU);
+
+	if (mtu)
+		goto out;
+
+	mtu = READ_ONCE(dst->dev->mtu);
+
+	if (unlikely(ip_mtu_locked(dst))) {
+		if (rt->rt_uses_gateway && mtu > 576)
+			mtu = 576;
+	}
+
+out:
+	mtu = min_t(unsigned int, mtu, IP_MAX_MTU);
+
+	return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
+}
+
+static void ip_del_fnhe(struct fib_nh *nh, __be32 daddr)
+{
+	struct fnhe_hash_bucket *hash;
+	struct fib_nh_exception *fnhe, __rcu **fnhe_p;
+	u32 hval = fnhe_hashfun(daddr);
+
+	spin_lock_bh(&fnhe_lock);
+
+	hash = rcu_dereference_protected(nh->nh_exceptions,
+					 lockdep_is_held(&fnhe_lock));
+	hash += hval;
+
+	fnhe_p = &hash->chain;
+	fnhe = rcu_dereference_protected(*fnhe_p, lockdep_is_held(&fnhe_lock));
+	while (fnhe) {
+		if (fnhe->fnhe_daddr == daddr) {
+			rcu_assign_pointer(*fnhe_p, rcu_dereference_protected(
+				fnhe->fnhe_next, lockdep_is_held(&fnhe_lock)));
+			/* set fnhe_daddr to 0 to ensure it won't bind with
+			 * new dsts in rt_bind_exception().
+			 */
+			fnhe->fnhe_daddr = 0;
+			fnhe_flush_routes(fnhe);
+			kfree_rcu(fnhe, rcu);
+			break;
+		}
+		fnhe_p = &fnhe->fnhe_next;
+		fnhe = rcu_dereference_protected(fnhe->fnhe_next,
+						 lockdep_is_held(&fnhe_lock));
+	}
+
+	spin_unlock_bh(&fnhe_lock);
+}
+
+static struct fib_nh_exception *find_exception(struct fib_nh *nh, __be32 daddr)
+{
+	struct fnhe_hash_bucket *hash = rcu_dereference(nh->nh_exceptions);
+	struct fib_nh_exception *fnhe;
+	u32 hval;
+
+	if (!hash)
+		return NULL;
+
+	hval = fnhe_hashfun(daddr);
+
+	for (fnhe = rcu_dereference(hash[hval].chain); fnhe;
+	     fnhe = rcu_dereference(fnhe->fnhe_next)) {
+		if (fnhe->fnhe_daddr == daddr) {
+			if (fnhe->fnhe_expires &&
+			    time_after(jiffies, fnhe->fnhe_expires)) {
+				ip_del_fnhe(nh, daddr);
+				break;
+			}
+			return fnhe;
+		}
+	}
+	return NULL;
+}
+
+/* MTU selection:
+ * 1. mtu on route is locked - use it
+ * 2. mtu from nexthop exception
+ * 3. mtu from egress device
+ */
+
+u32 ip_mtu_from_fib_result(struct fib_result *res, __be32 daddr)
+{
+	struct fib_info *fi = res->fi;
+	struct fib_nh *nh = &fi->fib_nh[res->nh_sel];
+	struct net_device *dev = nh->nh_dev;
+	u32 mtu = 0;
+
+	if (dev_net(dev)->ipv4.sysctl_ip_fwd_use_pmtu ||
+	    fi->fib_metrics->metrics[RTAX_LOCK - 1] & (1 << RTAX_MTU))
+		mtu = fi->fib_mtu;
+
+	if (likely(!mtu)) {
+		struct fib_nh_exception *fnhe;
+
+		fnhe = find_exception(nh, daddr);
+		if (fnhe && !time_after_eq(jiffies, fnhe->fnhe_expires))
+			mtu = fnhe->fnhe_pmtu;
+	}
+
+	if (likely(!mtu))
+		mtu = min(READ_ONCE(dev->mtu), IP_MAX_MTU);
+
+	return mtu - lwtunnel_headroom(nh->nh_lwtstate, mtu);
+}
+
+static bool rt_bind_exception(struct rtable *rt, struct fib_nh_exception *fnhe,
+			      __be32 daddr, const bool do_cache)
+{
+	bool ret = false;
+
+	spin_lock_bh(&fnhe_lock);
+
+	if (daddr == fnhe->fnhe_daddr) {
+		struct rtable __rcu **porig;
+		struct rtable *orig;
+		int genid = fnhe_genid(dev_net(rt->dst.dev));
+
+		if (rt_is_input_route(rt))
+			porig = &fnhe->fnhe_rth_input;
+		else
+			porig = &fnhe->fnhe_rth_output;
+		orig = rcu_dereference(*porig);
+
+		if (fnhe->fnhe_genid != genid) {
+			fnhe->fnhe_genid = genid;
+			fnhe->fnhe_gw = 0;
+			fnhe->fnhe_pmtu = 0;
+			fnhe->fnhe_expires = 0;
+			fnhe->fnhe_mtu_locked = false;
+			fnhe_flush_routes(fnhe);
+			orig = NULL;
+		}
+		fill_route_from_fnhe(rt, fnhe);
+		if (!rt->rt_gateway)
+			rt->rt_gateway = daddr;
+
+		if (do_cache) {
+			dst_hold(&rt->dst);
+			rcu_assign_pointer(*porig, rt);
+			if (orig) {
+				dst_dev_put(&orig->dst);
+				dst_release(&orig->dst);
+			}
+			ret = true;
+		}
+
+		fnhe->fnhe_stamp = jiffies;
+	}
+	spin_unlock_bh(&fnhe_lock);
+
+	return ret;
+}
+
+static bool rt_cache_route(struct fib_nh *nh, struct rtable *rt)
+{
+	struct rtable *orig, *prev, **p;
+	bool ret = true;
+
+	if (rt_is_input_route(rt)) {
+		p = (struct rtable **)&nh->nh_rth_input;
+	} else {
+		p = (struct rtable **)raw_cpu_ptr(nh->nh_pcpu_rth_output);
+	}
+	orig = *p;
+
+	/* hold dst before doing cmpxchg() to avoid race condition
+	 * on this dst
+	 */
+	dst_hold(&rt->dst);
+	prev = cmpxchg(p, orig, rt);
+	if (prev == orig) {
+		if (orig) {
+			rt_add_uncached_list(orig);
+			dst_release(&orig->dst);
+		}
+	} else {
+		dst_release(&rt->dst);
+		ret = false;
+	}
+
+	return ret;
+}
+
+struct uncached_list {
+	spinlock_t		lock;
+	struct list_head	head;
+};
+
+static DEFINE_PER_CPU_ALIGNED(struct uncached_list, rt_uncached_list);
+
+void rt_add_uncached_list(struct rtable *rt)
+{
+	struct uncached_list *ul = raw_cpu_ptr(&rt_uncached_list);
+
+	rt->rt_uncached_list = ul;
+
+	spin_lock_bh(&ul->lock);
+	list_add_tail(&rt->rt_uncached, &ul->head);
+	spin_unlock_bh(&ul->lock);
+}
+
+void rt_del_uncached_list(struct rtable *rt)
+{
+	if (!list_empty(&rt->rt_uncached)) {
+		struct uncached_list *ul = rt->rt_uncached_list;
+
+		spin_lock_bh(&ul->lock);
+		list_del(&rt->rt_uncached);
+		spin_unlock_bh(&ul->lock);
+	}
+}
+
+static void ipv4_dst_destroy(struct dst_entry *dst)
+{
+	struct dst_metrics *p = (struct dst_metrics *)DST_METRICS_PTR(dst);
+	struct rtable *rt = (struct rtable *)dst;
+
+	if (p != &dst_default_metrics && refcount_dec_and_test(&p->refcnt))
+		kfree(p);
+
+	rt_del_uncached_list(rt);
+}
+
+void rt_flush_dev(struct net_device *dev)
+{
+	struct net *net = dev_net(dev);
+	struct rtable *rt;
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
+
+		spin_lock_bh(&ul->lock);
+		list_for_each_entry(rt, &ul->head, rt_uncached) {
+			if (rt->dst.dev != dev)
+				continue;
+			rt->dst.dev = net->loopback_dev;
+			dev_hold(rt->dst.dev);
+			dev_put(dev);
+		}
+		spin_unlock_bh(&ul->lock);
+	}
+}
+
+static bool rt_cache_valid(const struct rtable *rt)
+{
+	return	rt &&
+		rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK &&
+		!rt_is_expired(rt);
+}
+
+static void rt_set_nexthop(struct rtable *rt, __be32 daddr,
+			   const struct fib_result *res,
+			   struct fib_nh_exception *fnhe,
+			   struct fib_info *fi, u16 type, u32 itag,
+			   const bool do_cache)
+{
+	bool cached = false;
+
+	if (fi) {
+		struct fib_nh *nh = &FIB_RES_NH(*res);
+
+		if (nh->nh_gw && nh->nh_scope == RT_SCOPE_LINK) {
+			rt->rt_gateway = nh->nh_gw;
+			rt->rt_uses_gateway = 1;
+		}
+		dst_init_metrics(&rt->dst, fi->fib_metrics->metrics, true);
+		if (fi->fib_metrics != &dst_default_metrics) {
+			rt->dst._metrics |= DST_METRICS_REFCOUNTED;
+			refcount_inc(&fi->fib_metrics->refcnt);
+		}
+#ifdef CONFIG_IP_ROUTE_CLASSID
+		rt->dst.tclassid = nh->nh_tclassid;
+#endif
+		rt->dst.lwtstate = lwtstate_get(nh->nh_lwtstate);
+		if (unlikely(fnhe))
+			cached = rt_bind_exception(rt, fnhe, daddr, do_cache);
+		else if (do_cache)
+			cached = rt_cache_route(nh, rt);
+		if (unlikely(!cached)) {
+			/* Routes we intend to cache in nexthop exception or
+			 * FIB nexthop have the DST_NOCACHE bit clear.
+			 * However, if we are unsuccessful at storing this
+			 * route into the cache we really need to set it.
+			 */
+			if (!rt->rt_gateway)
+				rt->rt_gateway = daddr;
+			rt_add_uncached_list(rt);
+		}
+	} else
+		rt_add_uncached_list(rt);
+
+#ifdef CONFIG_IP_ROUTE_CLASSID
+#ifdef CONFIG_IP_MULTIPLE_TABLES
+	set_class_tag(rt, res->tclassid);
+#endif
+	set_class_tag(rt, itag);
+#endif
+}
+
+struct rtable *rt_dst_alloc(struct net_device *dev,
+			    unsigned int flags, u16 type,
+			    bool nopolicy, bool noxfrm, bool will_cache)
+{
+	struct rtable *rt;
+
+	rt = dst_alloc(&ipv4_dst_ops, dev, 1, DST_OBSOLETE_FORCE_CHK,
+		       (will_cache ? 0 : DST_HOST) |
+		       (nopolicy ? DST_NOPOLICY : 0) |
+		       (noxfrm ? DST_NOXFRM : 0));
+
+	if (rt) {
+		rt->rt_genid = rt_genid_ipv4(dev_net(dev));
+		rt->rt_flags = flags;
+		rt->rt_type = type;
+		rt->rt_is_input = 0;
+		rt->rt_iif = 0;
+		rt->rt_pmtu = 0;
+		rt->rt_mtu_locked = 0;
+		rt->rt_gateway = 0;
+		rt->rt_uses_gateway = 0;
+		INIT_LIST_HEAD(&rt->rt_uncached);
+
+		rt->dst.output = ip_output;
+		if (flags & RTCF_LOCAL)
+			rt->dst.input = ip_local_deliver;
+	}
+
+	return rt;
+}
+EXPORT_SYMBOL(rt_dst_alloc);
+
+/* called in rcu_read_lock() section */
+int ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
+			  u8 tos, struct net_device *dev,
+			  struct in_device *in_dev, u32 *itag)
+{
+	int err;
+
+	/* Primary sanity checks. */
+	if (!in_dev)
+		return -EINVAL;
+
+	if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr) ||
+	    skb->protocol != htons(ETH_P_IP))
+		return -EINVAL;
+
+	if (ipv4_is_loopback(saddr) && !IN_DEV_ROUTE_LOCALNET(in_dev))
+		return -EINVAL;
+
+	if (ipv4_is_zeronet(saddr)) {
+		if (!ipv4_is_local_multicast(daddr))
+			return -EINVAL;
+	} else {
+		err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
+					  in_dev, itag);
+		if (err < 0)
+			return err;
+	}
+	return 0;
+}
+
+/* called in rcu_read_lock() section */
+static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
+			     u8 tos, struct net_device *dev, int our)
+{
+	struct in_device *in_dev = __in_dev_get_rcu(dev);
+	unsigned int flags = RTCF_MULTICAST;
+	struct rtable *rth;
+	u32 itag = 0;
+	int err;
+
+	err = ip_mc_validate_source(skb, daddr, saddr, tos, dev, in_dev, &itag);
+	if (err)
+		return err;
+
+	if (our)
+		flags |= RTCF_LOCAL;
+
+	rth = rt_dst_alloc(dev_net(dev)->loopback_dev, flags, RTN_MULTICAST,
+			   IN_DEV_CONF_GET(in_dev, NOPOLICY), false, false);
+	if (!rth)
+		return -ENOBUFS;
+
+#ifdef CONFIG_IP_ROUTE_CLASSID
+	rth->dst.tclassid = itag;
+#endif
+	rth->dst.output = ip_rt_bug;
+	rth->rt_is_input= 1;
+
+#ifdef CONFIG_IP_MROUTE
+	if (!ipv4_is_local_multicast(daddr) && IN_DEV_MFORWARD(in_dev))
+		rth->dst.input = ip_mr_input;
+#endif
+	RT_CACHE_STAT_INC(in_slow_mc);
+
+	skb_dst_drop(skb);
+	skb_dst_set(skb, &rth->dst);
+	return 0;
+}
+
+
+static void ip_handle_martian_source(struct net_device *dev,
+				     struct in_device *in_dev,
+				     struct sk_buff *skb,
+				     __be32 daddr,
+				     __be32 saddr)
+{
+	RT_CACHE_STAT_INC(in_martian_src);
+#ifdef CONFIG_IP_ROUTE_VERBOSE
+	if (IN_DEV_LOG_MARTIANS(in_dev) && net_ratelimit()) {
+		/*
+		 *	RFC1812 recommendation, if source is martian,
+		 *	the only hint is MAC header.
+		 */
+		pr_warn("martian source %pI4 from %pI4, on dev %s\n",
+			&daddr, &saddr, dev->name);
+		if (dev->hard_header_len && skb_mac_header_was_set(skb)) {
+			print_hex_dump(KERN_WARNING, "ll header: ",
+				       DUMP_PREFIX_OFFSET, 16, 1,
+				       skb_mac_header(skb),
+				       dev->hard_header_len, true);
+		}
+	}
+#endif
+}
+
+/* called in rcu_read_lock() section */
+static int __mkroute_input(struct sk_buff *skb,
+			   const struct fib_result *res,
+			   struct in_device *in_dev,
+			   __be32 daddr, __be32 saddr, u32 tos)
+{
+	struct fib_nh_exception *fnhe;
+	struct rtable *rth;
+	int err;
+	struct in_device *out_dev;
+	bool do_cache;
+	u32 itag = 0;
+
+	/* get a working reference to the output device */
+	out_dev = __in_dev_get_rcu(FIB_RES_DEV(*res));
+	if (!out_dev) {
+		net_crit_ratelimited("Bug in ip_route_input_slow(). Please report.\n");
+		return -EINVAL;
+	}
+
+	err = fib_validate_source(skb, saddr, daddr, tos, FIB_RES_OIF(*res),
+				  in_dev->dev, in_dev, &itag);
+	if (err < 0) {
+		ip_handle_martian_source(in_dev->dev, in_dev, skb, daddr,
+					 saddr);
+
+		goto cleanup;
+	}
+
+	do_cache = res->fi && !itag;
+	if (out_dev == in_dev && err && IN_DEV_TX_REDIRECTS(out_dev) &&
+	    skb->protocol == htons(ETH_P_IP) &&
+	    (IN_DEV_SHARED_MEDIA(out_dev) ||
+	     inet_addr_onlink(out_dev, saddr, FIB_RES_GW(*res))))
+		IPCB(skb)->flags |= IPSKB_DOREDIRECT;
+
+	if (skb->protocol != htons(ETH_P_IP)) {
+		/* Not IP (i.e. ARP). Do not create route, if it is
+		 * invalid for proxy arp. DNAT routes are always valid.
+		 *
+		 * Proxy arp feature have been extended to allow, ARP
+		 * replies back to the same interface, to support
+		 * Private VLAN switch technologies. See arp.c.
+		 */
+		if (out_dev == in_dev &&
+		    IN_DEV_PROXY_ARP_PVLAN(in_dev) == 0) {
+			err = -EINVAL;
+			goto cleanup;
+		}
+	}
+
+	fnhe = find_exception(&FIB_RES_NH(*res), daddr);
+	if (do_cache) {
+		if (fnhe)
+			rth = rcu_dereference(fnhe->fnhe_rth_input);
+		else
+			rth = rcu_dereference(FIB_RES_NH(*res).nh_rth_input);
+		if (rt_cache_valid(rth)) {
+			skb_dst_set_noref(skb, &rth->dst);
+			goto out;
+		}
+	}
+
+	rth = rt_dst_alloc(out_dev->dev, 0, res->type,
+			   IN_DEV_CONF_GET(in_dev, NOPOLICY),
+			   IN_DEV_CONF_GET(out_dev, NOXFRM), do_cache);
+	if (!rth) {
+		err = -ENOBUFS;
+		goto cleanup;
+	}
+
+	rth->rt_is_input = 1;
+	RT_CACHE_STAT_INC(in_slow_tot);
+
+	rth->dst.input = ip_forward;
+
+	rt_set_nexthop(rth, daddr, res, fnhe, res->fi, res->type, itag,
+		       do_cache);
+	lwtunnel_set_redirect(&rth->dst);
+	skb_dst_set(skb, &rth->dst);
+out:
+	err = 0;
+ cleanup:
+	return err;
+}
+
+#ifdef CONFIG_IP_ROUTE_MULTIPATH
+/* To make ICMP packets follow the right flow, the multipath hash is
+ * calculated from the inner IP addresses.
+ */
+static void ip_multipath_l3_keys(const struct sk_buff *skb,
+				 struct flow_keys *hash_keys)
+{
+	const struct iphdr *outer_iph = ip_hdr(skb);
+	const struct iphdr *key_iph = outer_iph;
+	const struct iphdr *inner_iph;
+	const struct icmphdr *icmph;
+	struct iphdr _inner_iph;
+	struct icmphdr _icmph;
+
+	if (likely(outer_iph->protocol != IPPROTO_ICMP))
+		goto out;
+
+	if (unlikely((outer_iph->frag_off & htons(IP_OFFSET)) != 0))
+		goto out;
+
+	icmph = skb_header_pointer(skb, outer_iph->ihl * 4, sizeof(_icmph),
+				   &_icmph);
+	if (!icmph)
+		goto out;
+
+	if (icmph->type != ICMP_DEST_UNREACH &&
+	    icmph->type != ICMP_REDIRECT &&
+	    icmph->type != ICMP_TIME_EXCEEDED &&
+	    icmph->type != ICMP_PARAMETERPROB)
+		goto out;
+
+	inner_iph = skb_header_pointer(skb,
+				       outer_iph->ihl * 4 + sizeof(_icmph),
+				       sizeof(_inner_iph), &_inner_iph);
+	if (!inner_iph)
+		goto out;
+
+	key_iph = inner_iph;
+out:
+	hash_keys->addrs.v4addrs.src = key_iph->saddr;
+	hash_keys->addrs.v4addrs.dst = key_iph->daddr;
+}
+
+/* if skb is set it will be used and fl4 can be NULL */
+int fib_multipath_hash(const struct net *net, const struct flowi4 *fl4,
+		       const struct sk_buff *skb, struct flow_keys *flkeys)
+{
+	struct flow_keys hash_keys;
+	u32 mhash;
+
+	switch (net->ipv4.sysctl_fib_multipath_hash_policy) {
+	case 0:
+		memset(&hash_keys, 0, sizeof(hash_keys));
+		hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
+		if (skb) {
+			ip_multipath_l3_keys(skb, &hash_keys);
+		} else {
+			hash_keys.addrs.v4addrs.src = fl4->saddr;
+			hash_keys.addrs.v4addrs.dst = fl4->daddr;
+		}
+		break;
+	case 1:
+		/* skb is currently provided only when forwarding */
+		if (skb) {
+			unsigned int flag = FLOW_DISSECTOR_F_STOP_AT_ENCAP;
+			struct flow_keys keys;
+
+			/* short-circuit if we already have L4 hash present */
+			if (skb->l4_hash)
+				return skb_get_hash_raw(skb) >> 1;
+
+			memset(&hash_keys, 0, sizeof(hash_keys));
+
+			if (!flkeys) {
+				skb_flow_dissect_flow_keys(skb, &keys, flag);
+				flkeys = &keys;
+			}
+
+			hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
+			hash_keys.addrs.v4addrs.src = flkeys->addrs.v4addrs.src;
+			hash_keys.addrs.v4addrs.dst = flkeys->addrs.v4addrs.dst;
+			hash_keys.ports.src = flkeys->ports.src;
+			hash_keys.ports.dst = flkeys->ports.dst;
+			hash_keys.basic.ip_proto = flkeys->basic.ip_proto;
+		} else {
+			memset(&hash_keys, 0, sizeof(hash_keys));
+			hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
+			hash_keys.addrs.v4addrs.src = fl4->saddr;
+			hash_keys.addrs.v4addrs.dst = fl4->daddr;
+			hash_keys.ports.src = fl4->fl4_sport;
+			hash_keys.ports.dst = fl4->fl4_dport;
+			hash_keys.basic.ip_proto = fl4->flowi4_proto;
+		}
+		break;
+	}
+	mhash = flow_hash_from_keys(&hash_keys);
+
+	return mhash >> 1;
+}
+#endif /* CONFIG_IP_ROUTE_MULTIPATH */
+
+static int ip_mkroute_input(struct sk_buff *skb,
+			    struct fib_result *res,
+			    struct in_device *in_dev,
+			    __be32 daddr, __be32 saddr, u32 tos,
+			    struct flow_keys *hkeys)
+{
+#ifdef CONFIG_IP_ROUTE_MULTIPATH
+	if (res->fi && res->fi->fib_nhs > 1) {
+		int h = fib_multipath_hash(res->fi->fib_net, NULL, skb, hkeys);
+
+		fib_select_multipath(res, h);
+	}
+#endif
+
+	/* create a routing cache entry */
+	return __mkroute_input(skb, res, in_dev, daddr, saddr, tos);
+}
+
+/*
+ *	NOTE. We drop all the packets that has local source
+ *	addresses, because every properly looped back packet
+ *	must have correct destination already attached by output routine.
+ *
+ *	Such approach solves two big problems:
+ *	1. Not simplex devices are handled properly.
+ *	2. IP spoofing attempts are filtered with 100% of guarantee.
+ *	called with rcu_read_lock()
+ */
+
+static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
+			       u8 tos, struct net_device *dev,
+			       struct fib_result *res)
+{
+	struct in_device *in_dev = __in_dev_get_rcu(dev);
+	struct flow_keys *flkeys = NULL, _flkeys;
+	struct net    *net = dev_net(dev);
+	struct ip_tunnel_info *tun_info;
+	int		err = -EINVAL;
+	unsigned int	flags = 0;
+	u32		itag = 0;
+	struct rtable	*rth;
+	struct flowi4	fl4;
+	bool do_cache = true;
+
+	/* IP on this device is disabled. */
+
+	if (!in_dev)
+		goto out;
+
+	/* Check for the most weird martians, which can be not detected
+	   by fib_lookup.
+	 */
+
+	tun_info = skb_tunnel_info(skb);
+	if (tun_info && !(tun_info->mode & IP_TUNNEL_INFO_TX))
+		fl4.flowi4_tun_key.tun_id = tun_info->key.tun_id;
+	else
+		fl4.flowi4_tun_key.tun_id = 0;
+	skb_dst_drop(skb);
+
+	if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
+		goto martian_source;
+
+	res->fi = NULL;
+	res->table = NULL;
+	if (ipv4_is_lbcast(daddr) || (saddr == 0 && daddr == 0))
+		goto brd_input;
+
+	/* Accept zero addresses only to limited broadcast;
+	 * I even do not know to fix it or not. Waiting for complains :-)
+	 */
+	if (ipv4_is_zeronet(saddr))
+		goto martian_source;
+
+	if (ipv4_is_zeronet(daddr))
+		goto martian_destination;
+
+	/* Following code try to avoid calling IN_DEV_NET_ROUTE_LOCALNET(),
+	 * and call it once if daddr or/and saddr are loopback addresses
+	 */
+	if (ipv4_is_loopback(daddr)) {
+		if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
+			goto martian_destination;
+	} else if (ipv4_is_loopback(saddr)) {
+		if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
+			goto martian_source;
+	}
+
+	/*
+	 *	Now we are ready to route packet.
+	 */
+	fl4.flowi4_oif = 0;
+	fl4.flowi4_iif = dev->ifindex;
+	fl4.flowi4_mark = skb->mark;
+	fl4.flowi4_tos = tos;
+	fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
+	fl4.flowi4_flags = 0;
+	fl4.daddr = daddr;
+	fl4.saddr = saddr;
+	fl4.flowi4_uid = sock_net_uid(net, NULL);
+
+	if (fib4_rules_early_flow_dissect(net, skb, &fl4, &_flkeys)) {
+		flkeys = &_flkeys;
+	} else {
+		fl4.flowi4_proto = 0;
+		fl4.fl4_sport = 0;
+		fl4.fl4_dport = 0;
+	}
+
+	err = fib_lookup(net, &fl4, res, 0);
+	if (err != 0) {
+		if (!IN_DEV_FORWARD(in_dev))
+			err = -EHOSTUNREACH;
+		goto no_route;
+	}
+
+	if (res->type == RTN_BROADCAST) {
+		if (IN_DEV_BFORWARD(in_dev))
+			goto make_route;
+		/* not do cache if bc_forwarding is enabled */
+		if (IPV4_DEVCONF_ALL(net, BC_FORWARDING))
+			do_cache = false;
+		goto brd_input;
+	}
+
+	if (res->type == RTN_LOCAL) {
+		err = fib_validate_source(skb, saddr, daddr, tos,
+					  0, dev, in_dev, &itag);
+		if (err < 0)
+			goto martian_source;
+		goto local_input;
+	}
+
+	if (!IN_DEV_FORWARD(in_dev)) {
+		err = -EHOSTUNREACH;
+		goto no_route;
+	}
+	if (res->type != RTN_UNICAST)
+		goto martian_destination;
+
+make_route:
+	err = ip_mkroute_input(skb, res, in_dev, daddr, saddr, tos, flkeys);
+out:	return err;
+
+brd_input:
+	if (skb->protocol != htons(ETH_P_IP))
+		goto e_inval;
+
+	if (!ipv4_is_zeronet(saddr)) {
+		err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
+					  in_dev, &itag);
+		if (err < 0)
+			goto martian_source;
+	}
+	flags |= RTCF_BROADCAST;
+	res->type = RTN_BROADCAST;
+	RT_CACHE_STAT_INC(in_brd);
+
+local_input:
+	do_cache &= res->fi && !itag;
+	if (do_cache) {
+		rth = rcu_dereference(FIB_RES_NH(*res).nh_rth_input);
+		if (rt_cache_valid(rth)) {
+			skb_dst_set_noref(skb, &rth->dst);
+			err = 0;
+			goto out;
+		}
+	}
+
+	rth = rt_dst_alloc(l3mdev_master_dev_rcu(dev) ? : net->loopback_dev,
+			   flags | RTCF_LOCAL, res->type,
+			   IN_DEV_CONF_GET(in_dev, NOPOLICY), false, do_cache);
+	if (!rth)
+		goto e_nobufs;
+
+	rth->dst.output= ip_rt_bug;
+#ifdef CONFIG_IP_ROUTE_CLASSID
+	rth->dst.tclassid = itag;
+#endif
+	rth->rt_is_input = 1;
+
+	RT_CACHE_STAT_INC(in_slow_tot);
+	if (res->type == RTN_UNREACHABLE) {
+		rth->dst.input= ip_error;
+		rth->dst.error= -err;
+		rth->rt_flags 	&= ~RTCF_LOCAL;
+	}
+
+	if (do_cache) {
+		struct fib_nh *nh = &FIB_RES_NH(*res);
+
+		rth->dst.lwtstate = lwtstate_get(nh->nh_lwtstate);
+		if (lwtunnel_input_redirect(rth->dst.lwtstate)) {
+			WARN_ON(rth->dst.input == lwtunnel_input);
+			rth->dst.lwtstate->orig_input = rth->dst.input;
+			rth->dst.input = lwtunnel_input;
+		}
+
+		if (unlikely(!rt_cache_route(nh, rth)))
+			rt_add_uncached_list(rth);
+	}
+	skb_dst_set(skb, &rth->dst);
+	err = 0;
+	goto out;
+
+no_route:
+	RT_CACHE_STAT_INC(in_no_route);
+	res->type = RTN_UNREACHABLE;
+	res->fi = NULL;
+	res->table = NULL;
+	goto local_input;
+
+	/*
+	 *	Do not cache martian addresses: they should be logged (RFC1812)
+	 */
+martian_destination:
+	RT_CACHE_STAT_INC(in_martian_dst);
+#ifdef CONFIG_IP_ROUTE_VERBOSE
+	if (IN_DEV_LOG_MARTIANS(in_dev))
+		net_warn_ratelimited("martian destination %pI4 from %pI4, dev %s\n",
+				     &daddr, &saddr, dev->name);
+#endif
+
+e_inval:
+	err = -EINVAL;
+	goto out;
+
+e_nobufs:
+	err = -ENOBUFS;
+	goto out;
+
+martian_source:
+	ip_handle_martian_source(dev, in_dev, skb, daddr, saddr);
+	goto out;
+}
+
+int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
+			 u8 tos, struct net_device *dev)
+{
+	struct fib_result res;
+	int err;
+
+	tos &= IPTOS_RT_MASK;
+	rcu_read_lock();
+	err = ip_route_input_rcu(skb, daddr, saddr, tos, dev, &res);
+	rcu_read_unlock();
+
+	return err;
+}
+EXPORT_SYMBOL(ip_route_input_noref);
+
+/* called with rcu_read_lock held */
+int ip_route_input_rcu(struct sk_buff *skb, __be32 daddr, __be32 saddr,
+		       u8 tos, struct net_device *dev, struct fib_result *res)
+{
+	/* Multicast recognition logic is moved from route cache to here.
+	   The problem was that too many Ethernet cards have broken/missing
+	   hardware multicast filters :-( As result the host on multicasting
+	   network acquires a lot of useless route cache entries, sort of
+	   SDR messages from all the world. Now we try to get rid of them.
+	   Really, provided software IP multicast filter is organized
+	   reasonably (at least, hashed), it does not result in a slowdown
+	   comparing with route cache reject entries.
+	   Note, that multicast routers are not affected, because
+	   route cache entry is created eventually.
+	 */
+	if (ipv4_is_multicast(daddr)) {
+		struct in_device *in_dev = __in_dev_get_rcu(dev);
+		int our = 0;
+		int err = -EINVAL;
+
+		if (!in_dev)
+			return err;
+		our = ip_check_mc_rcu(in_dev, daddr, saddr,
+				      ip_hdr(skb)->protocol);
+
+		/* check l3 master if no match yet */
+		if (!our && netif_is_l3_slave(dev)) {
+			struct in_device *l3_in_dev;
+
+			l3_in_dev = __in_dev_get_rcu(skb->dev);
+			if (l3_in_dev)
+				our = ip_check_mc_rcu(l3_in_dev, daddr, saddr,
+						      ip_hdr(skb)->protocol);
+		}
+
+		if (our
+#ifdef CONFIG_IP_MROUTE
+			||
+		    (!ipv4_is_local_multicast(daddr) &&
+		     IN_DEV_MFORWARD(in_dev))
+#endif
+		   ) {
+			err = ip_route_input_mc(skb, daddr, saddr,
+						tos, dev, our);
+		}
+		return err;
+	}
+
+	return ip_route_input_slow(skb, daddr, saddr, tos, dev, res);
+}
+
+/* called with rcu_read_lock() */
+static struct rtable *__mkroute_output(const struct fib_result *res,
+				       const struct flowi4 *fl4, int orig_oif,
+				       struct net_device *dev_out,
+				       unsigned int flags)
+{
+	struct fib_info *fi = res->fi;
+	struct fib_nh_exception *fnhe;
+	struct in_device *in_dev;
+	u16 type = res->type;
+	struct rtable *rth;
+	bool do_cache;
+
+	in_dev = __in_dev_get_rcu(dev_out);
+	if (!in_dev)
+		return ERR_PTR(-EINVAL);
+
+	if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev)))
+		if (ipv4_is_loopback(fl4->saddr) &&
+		    !(dev_out->flags & IFF_LOOPBACK) &&
+		    !netif_is_l3_master(dev_out))
+			return ERR_PTR(-EINVAL);
+
+	if (ipv4_is_lbcast(fl4->daddr))
+		type = RTN_BROADCAST;
+	else if (ipv4_is_multicast(fl4->daddr))
+		type = RTN_MULTICAST;
+	else if (ipv4_is_zeronet(fl4->daddr))
+		return ERR_PTR(-EINVAL);
+
+	if (dev_out->flags & IFF_LOOPBACK)
+		flags |= RTCF_LOCAL;
+
+	do_cache = true;
+	if (type == RTN_BROADCAST) {
+		flags |= RTCF_BROADCAST | RTCF_LOCAL;
+		fi = NULL;
+	} else if (type == RTN_MULTICAST) {
+		flags |= RTCF_MULTICAST | RTCF_LOCAL;
+		if (!ip_check_mc_rcu(in_dev, fl4->daddr, fl4->saddr,
+				     fl4->flowi4_proto))
+			flags &= ~RTCF_LOCAL;
+		else
+			do_cache = false;
+		/* If multicast route do not exist use
+		 * default one, but do not gateway in this case.
+		 * Yes, it is hack.
+		 */
+		if (fi && res->prefixlen < 4)
+			fi = NULL;
+	} else if ((type == RTN_LOCAL) && (orig_oif != 0) &&
+		   (orig_oif != dev_out->ifindex)) {
+		/* For local routes that require a particular output interface
+		 * we do not want to cache the result.  Caching the result
+		 * causes incorrect behaviour when there are multiple source
+		 * addresses on the interface, the end result being that if the
+		 * intended recipient is waiting on that interface for the
+		 * packet he won't receive it because it will be delivered on
+		 * the loopback interface and the IP_PKTINFO ipi_ifindex will
+		 * be set to the loopback interface as well.
+		 */
+		do_cache = false;
+	}
+
+	fnhe = NULL;
+	do_cache &= fi != NULL;
+	if (fi) {
+		struct rtable __rcu **prth;
+		struct fib_nh *nh = &FIB_RES_NH(*res);
+
+		fnhe = find_exception(nh, fl4->daddr);
+		if (!do_cache)
+			goto add;
+		if (fnhe) {
+			prth = &fnhe->fnhe_rth_output;
+		} else {
+			if (unlikely(fl4->flowi4_flags &
+				     FLOWI_FLAG_KNOWN_NH &&
+				     !(nh->nh_gw &&
+				       nh->nh_scope == RT_SCOPE_LINK))) {
+				do_cache = false;
+				goto add;
+			}
+			prth = raw_cpu_ptr(nh->nh_pcpu_rth_output);
+		}
+		rth = rcu_dereference(*prth);
+		if (rt_cache_valid(rth) && dst_hold_safe(&rth->dst))
+			return rth;
+	}
+
+add:
+	rth = rt_dst_alloc(dev_out, flags, type,
+			   IN_DEV_CONF_GET(in_dev, NOPOLICY),
+			   IN_DEV_CONF_GET(in_dev, NOXFRM),
+			   do_cache);
+	if (!rth)
+		return ERR_PTR(-ENOBUFS);
+
+	rth->rt_iif = orig_oif;
+
+	RT_CACHE_STAT_INC(out_slow_tot);
+
+	if (flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
+		if (flags & RTCF_LOCAL &&
+		    !(dev_out->flags & IFF_LOOPBACK)) {
+			rth->dst.output = ip_mc_output;
+			RT_CACHE_STAT_INC(out_slow_mc);
+		}
+#ifdef CONFIG_IP_MROUTE
+		if (type == RTN_MULTICAST) {
+			if (IN_DEV_MFORWARD(in_dev) &&
+			    !ipv4_is_local_multicast(fl4->daddr)) {
+				rth->dst.input = ip_mr_input;
+				rth->dst.output = ip_mc_output;
+			}
+		}
+#endif
+	}
+
+	rt_set_nexthop(rth, fl4->daddr, res, fnhe, fi, type, 0, do_cache);
+	lwtunnel_set_redirect(&rth->dst);
+
+	return rth;
+}
+
+/*
+ * Major route resolver routine.
+ */
+
+struct rtable *ip_route_output_key_hash(struct net *net, struct flowi4 *fl4,
+					const struct sk_buff *skb)
+{
+	__u8 tos = RT_FL_TOS(fl4);
+	struct fib_result res = {
+		.type		= RTN_UNSPEC,
+		.fi		= NULL,
+		.table		= NULL,
+		.tclassid	= 0,
+	};
+	struct rtable *rth;
+
+	fl4->flowi4_iif = LOOPBACK_IFINDEX;
+	fl4->flowi4_tos = tos & IPTOS_RT_MASK;
+	fl4->flowi4_scope = ((tos & RTO_ONLINK) ?
+			 RT_SCOPE_LINK : RT_SCOPE_UNIVERSE);
+
+	rcu_read_lock();
+	rth = ip_route_output_key_hash_rcu(net, fl4, &res, skb);
+	rcu_read_unlock();
+
+	return rth;
+}
+EXPORT_SYMBOL_GPL(ip_route_output_key_hash);
+
+struct rtable *ip_route_output_key_hash_rcu(struct net *net, struct flowi4 *fl4,
+					    struct fib_result *res,
+					    const struct sk_buff *skb)
+{
+	struct net_device *dev_out = NULL;
+	int orig_oif = fl4->flowi4_oif;
+	unsigned int flags = 0;
+	struct rtable *rth;
+	int err;
+
+	if (fl4->saddr) {
+		if (ipv4_is_multicast(fl4->saddr) ||
+		    ipv4_is_lbcast(fl4->saddr) ||
+		    ipv4_is_zeronet(fl4->saddr)) {
+			rth = ERR_PTR(-EINVAL);
+			goto out;
+		}
+
+		rth = ERR_PTR(-ENETUNREACH);
+
+		/* I removed check for oif == dev_out->oif here.
+		   It was wrong for two reasons:
+		   1. ip_dev_find(net, saddr) can return wrong iface, if saddr
+		      is assigned to multiple interfaces.
+		   2. Moreover, we are allowed to send packets with saddr
+		      of another iface. --ANK
+		 */
+
+		if (fl4->flowi4_oif == 0 &&
+		    (ipv4_is_multicast(fl4->daddr) ||
+		     ipv4_is_lbcast(fl4->daddr))) {
+			/* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
+			dev_out = __ip_dev_find(net, fl4->saddr, false);
+			if (!dev_out)
+				goto out;
+
+			/* Special hack: user can direct multicasts
+			   and limited broadcast via necessary interface
+			   without fiddling with IP_MULTICAST_IF or IP_PKTINFO.
+			   This hack is not just for fun, it allows
+			   vic,vat and friends to work.
+			   They bind socket to loopback, set ttl to zero
+			   and expect that it will work.
+			   From the viewpoint of routing cache they are broken,
+			   because we are not allowed to build multicast path
+			   with loopback source addr (look, routing cache
+			   cannot know, that ttl is zero, so that packet
+			   will not leave this host and route is valid).
+			   Luckily, this hack is good workaround.
+			 */
+
+			fl4->flowi4_oif = dev_out->ifindex;
+			goto make_route;
+		}
+
+		if (!(fl4->flowi4_flags & FLOWI_FLAG_ANYSRC)) {
+			/* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
+			if (!__ip_dev_find(net, fl4->saddr, false))
+				goto out;
+		}
+	}
+
+
+	if (fl4->flowi4_oif) {
+		dev_out = dev_get_by_index_rcu(net, fl4->flowi4_oif);
+		rth = ERR_PTR(-ENODEV);
+		if (!dev_out)
+			goto out;
+
+		/* RACE: Check return value of inet_select_addr instead. */
+		if (!(dev_out->flags & IFF_UP) || !__in_dev_get_rcu(dev_out)) {
+			rth = ERR_PTR(-ENETUNREACH);
+			goto out;
+		}
+		if (ipv4_is_local_multicast(fl4->daddr) ||
+		    ipv4_is_lbcast(fl4->daddr) ||
+		    fl4->flowi4_proto == IPPROTO_IGMP) {
+			if (!fl4->saddr)
+				fl4->saddr = inet_select_addr(dev_out, 0,
+							      RT_SCOPE_LINK);
+			goto make_route;
+		}
+		if (!fl4->saddr) {
+			if (ipv4_is_multicast(fl4->daddr))
+				fl4->saddr = inet_select_addr(dev_out, 0,
+							      fl4->flowi4_scope);
+			else if (!fl4->daddr)
+				fl4->saddr = inet_select_addr(dev_out, 0,
+							      RT_SCOPE_HOST);
+		}
+	}
+
+	if (!fl4->daddr) {
+		fl4->daddr = fl4->saddr;
+		if (!fl4->daddr)
+			fl4->daddr = fl4->saddr = htonl(INADDR_LOOPBACK);
+		dev_out = net->loopback_dev;
+		fl4->flowi4_oif = LOOPBACK_IFINDEX;
+		res->type = RTN_LOCAL;
+		flags |= RTCF_LOCAL;
+		goto make_route;
+	}
+
+	err = fib_lookup(net, fl4, res, 0);
+	if (err) {
+		res->fi = NULL;
+		res->table = NULL;
+		if (fl4->flowi4_oif &&
+		    (ipv4_is_multicast(fl4->daddr) ||
+		    !netif_index_is_l3_master(net, fl4->flowi4_oif))) {
+			/* Apparently, routing tables are wrong. Assume,
+			   that the destination is on link.
+
+			   WHY? DW.
+			   Because we are allowed to send to iface
+			   even if it has NO routes and NO assigned
+			   addresses. When oif is specified, routing
+			   tables are looked up with only one purpose:
+			   to catch if destination is gatewayed, rather than
+			   direct. Moreover, if MSG_DONTROUTE is set,
+			   we send packet, ignoring both routing tables
+			   and ifaddr state. --ANK
+
+
+			   We could make it even if oif is unknown,
+			   likely IPv6, but we do not.
+			 */
+
+			if (fl4->saddr == 0)
+				fl4->saddr = inet_select_addr(dev_out, 0,
+							      RT_SCOPE_LINK);
+			res->type = RTN_UNICAST;
+			goto make_route;
+		}
+		rth = ERR_PTR(err);
+		goto out;
+	}
+
+	if (res->type == RTN_LOCAL) {
+		if (!fl4->saddr) {
+			if (res->fi->fib_prefsrc)
+				fl4->saddr = res->fi->fib_prefsrc;
+			else
+				fl4->saddr = fl4->daddr;
+		}
+
+		/* L3 master device is the loopback for that domain */
+		dev_out = l3mdev_master_dev_rcu(FIB_RES_DEV(*res)) ? :
+			net->loopback_dev;
+
+		/* make sure orig_oif points to fib result device even
+		 * though packet rx/tx happens over loopback or l3mdev
+		 */
+		orig_oif = FIB_RES_OIF(*res);
+
+		fl4->flowi4_oif = dev_out->ifindex;
+		flags |= RTCF_LOCAL;
+		goto make_route;
+	}
+
+	fib_select_path(net, res, fl4, skb);
+
+	dev_out = FIB_RES_DEV(*res);
+
+make_route:
+	rth = __mkroute_output(res, fl4, orig_oif, dev_out, flags);
+
+out:
+	return rth;
+}
+
+static struct dst_entry *ipv4_blackhole_dst_check(struct dst_entry *dst, u32 cookie)
+{
+	return NULL;
+}
+
+static unsigned int ipv4_blackhole_mtu(const struct dst_entry *dst)
+{
+	unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
+
+	return mtu ? : dst->dev->mtu;
+}
+
+static void ipv4_rt_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
+					  struct sk_buff *skb, u32 mtu,
+					  bool confirm_neigh)
+{
+}
+
+static void ipv4_rt_blackhole_redirect(struct dst_entry *dst, struct sock *sk,
+				       struct sk_buff *skb)
+{
+}
+
+static u32 *ipv4_rt_blackhole_cow_metrics(struct dst_entry *dst,
+					  unsigned long old)
+{
+	return NULL;
+}
+
+static struct dst_ops ipv4_dst_blackhole_ops = {
+	.family			=	AF_INET,
+	.check			=	ipv4_blackhole_dst_check,
+	.mtu			=	ipv4_blackhole_mtu,
+	.default_advmss		=	ipv4_default_advmss,
+	.update_pmtu		=	ipv4_rt_blackhole_update_pmtu,
+	.redirect		=	ipv4_rt_blackhole_redirect,
+	.cow_metrics		=	ipv4_rt_blackhole_cow_metrics,
+	.neigh_lookup		=	ipv4_neigh_lookup,
+};
+
+struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_orig)
+{
+	struct rtable *ort = (struct rtable *) dst_orig;
+	struct rtable *rt;
+
+	rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, 1, DST_OBSOLETE_DEAD, 0);
+	if (rt) {
+		struct dst_entry *new = &rt->dst;
+
+		new->__use = 1;
+		new->input = dst_discard;
+		new->output = dst_discard_out;
+
+		new->dev = net->loopback_dev;
+		if (new->dev)
+			dev_hold(new->dev);
+
+		rt->rt_is_input = ort->rt_is_input;
+		rt->rt_iif = ort->rt_iif;
+		rt->rt_pmtu = ort->rt_pmtu;
+		rt->rt_mtu_locked = ort->rt_mtu_locked;
+
+		rt->rt_genid = rt_genid_ipv4(net);
+		rt->rt_flags = ort->rt_flags;
+		rt->rt_type = ort->rt_type;
+		rt->rt_gateway = ort->rt_gateway;
+		rt->rt_uses_gateway = ort->rt_uses_gateway;
+
+		INIT_LIST_HEAD(&rt->rt_uncached);
+	}
+
+	dst_release(dst_orig);
+
+	return rt ? &rt->dst : ERR_PTR(-ENOMEM);
+}
+
+struct rtable *ip_route_output_flow(struct net *net, struct flowi4 *flp4,
+				    const struct sock *sk)
+{
+	struct rtable *rt = __ip_route_output_key(net, flp4);
+
+	if (IS_ERR(rt))
+		return rt;
+
+	if (flp4->flowi4_proto) {
+		flp4->flowi4_oif = rt->dst.dev->ifindex;
+		rt = (struct rtable *)xfrm_lookup_route(net, &rt->dst,
+							flowi4_to_flowi(flp4),
+							sk, 0);
+	}
+
+	return rt;
+}
+EXPORT_SYMBOL_GPL(ip_route_output_flow);
+
+/* called with rcu_read_lock held */
+static int rt_fill_info(struct net *net, __be32 dst, __be32 src,
+			struct rtable *rt, u32 table_id, struct flowi4 *fl4,
+			struct sk_buff *skb, u32 portid, u32 seq)
+{
+	struct rtmsg *r;
+	struct nlmsghdr *nlh;
+	unsigned long expires = 0;
+	u32 error;
+	u32 metrics[RTAX_MAX];
+
+	nlh = nlmsg_put(skb, portid, seq, RTM_NEWROUTE, sizeof(*r), 0);
+	if (!nlh)
+		return -EMSGSIZE;
+
+	r = nlmsg_data(nlh);
+	r->rtm_family	 = AF_INET;
+	r->rtm_dst_len	= 32;
+	r->rtm_src_len	= 0;
+	r->rtm_tos	= fl4->flowi4_tos;
+	r->rtm_table	= table_id < 256 ? table_id : RT_TABLE_COMPAT;
+	if (nla_put_u32(skb, RTA_TABLE, table_id))
+		goto nla_put_failure;
+	r->rtm_type	= rt->rt_type;
+	r->rtm_scope	= RT_SCOPE_UNIVERSE;
+	r->rtm_protocol = RTPROT_UNSPEC;
+	r->rtm_flags	= (rt->rt_flags & ~0xFFFF) | RTM_F_CLONED;
+	if (rt->rt_flags & RTCF_NOTIFY)
+		r->rtm_flags |= RTM_F_NOTIFY;
+	if (IPCB(skb)->flags & IPSKB_DOREDIRECT)
+		r->rtm_flags |= RTCF_DOREDIRECT;
+
+	if (nla_put_in_addr(skb, RTA_DST, dst))
+		goto nla_put_failure;
+	if (src) {
+		r->rtm_src_len = 32;
+		if (nla_put_in_addr(skb, RTA_SRC, src))
+			goto nla_put_failure;
+	}
+	if (rt->dst.dev &&
+	    nla_put_u32(skb, RTA_OIF, rt->dst.dev->ifindex))
+		goto nla_put_failure;
+#ifdef CONFIG_IP_ROUTE_CLASSID
+	if (rt->dst.tclassid &&
+	    nla_put_u32(skb, RTA_FLOW, rt->dst.tclassid))
+		goto nla_put_failure;
+#endif
+	if (!rt_is_input_route(rt) &&
+	    fl4->saddr != src) {
+		if (nla_put_in_addr(skb, RTA_PREFSRC, fl4->saddr))
+			goto nla_put_failure;
+	}
+	if (rt->rt_uses_gateway &&
+	    nla_put_in_addr(skb, RTA_GATEWAY, rt->rt_gateway))
+		goto nla_put_failure;
+
+	expires = rt->dst.expires;
+	if (expires) {
+		unsigned long now = jiffies;
+
+		if (time_before(now, expires))
+			expires -= now;
+		else
+			expires = 0;
+	}
+
+	memcpy(metrics, dst_metrics_ptr(&rt->dst), sizeof(metrics));
+	if (rt->rt_pmtu && expires)
+		metrics[RTAX_MTU - 1] = rt->rt_pmtu;
+	if (rt->rt_mtu_locked && expires)
+		metrics[RTAX_LOCK - 1] |= BIT(RTAX_MTU);
+	if (rtnetlink_put_metrics(skb, metrics) < 0)
+		goto nla_put_failure;
+
+	if (fl4->flowi4_mark &&
+	    nla_put_u32(skb, RTA_MARK, fl4->flowi4_mark))
+		goto nla_put_failure;
+
+	if (!uid_eq(fl4->flowi4_uid, INVALID_UID) &&
+	    nla_put_u32(skb, RTA_UID,
+			from_kuid_munged(current_user_ns(), fl4->flowi4_uid)))
+		goto nla_put_failure;
+
+	error = rt->dst.error;
+
+	if (rt_is_input_route(rt)) {
+#ifdef CONFIG_IP_MROUTE
+		if (ipv4_is_multicast(dst) && !ipv4_is_local_multicast(dst) &&
+		    IPV4_DEVCONF_ALL(net, MC_FORWARDING)) {
+			int err = ipmr_get_route(net, skb,
+						 fl4->saddr, fl4->daddr,
+						 r, portid);
+
+			if (err <= 0) {
+				if (err == 0)
+					return 0;
+				goto nla_put_failure;
+			}
+		} else
+#endif
+			if (nla_put_u32(skb, RTA_IIF, fl4->flowi4_iif))
+				goto nla_put_failure;
+	}
+
+	if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, error) < 0)
+		goto nla_put_failure;
+
+	nlmsg_end(skb, nlh);
+	return 0;
+
+nla_put_failure:
+	nlmsg_cancel(skb, nlh);
+	return -EMSGSIZE;
+}
+
+static struct sk_buff *inet_rtm_getroute_build_skb(__be32 src, __be32 dst,
+						   u8 ip_proto, __be16 sport,
+						   __be16 dport)
+{
+	struct sk_buff *skb;
+	struct iphdr *iph;
+
+	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
+	if (!skb)
+		return NULL;
+
+	/* Reserve room for dummy headers, this skb can pass
+	 * through good chunk of routing engine.
+	 */
+	skb_reset_mac_header(skb);
+	skb_reset_network_header(skb);
+	skb->protocol = htons(ETH_P_IP);
+	iph = skb_put(skb, sizeof(struct iphdr));
+	iph->protocol = ip_proto;
+	iph->saddr = src;
+	iph->daddr = dst;
+	iph->version = 0x4;
+	iph->frag_off = 0;
+	iph->ihl = 0x5;
+	skb_set_transport_header(skb, skb->len);
+
+	switch (iph->protocol) {
+	case IPPROTO_UDP: {
+		struct udphdr *udph;
+
+		udph = skb_put_zero(skb, sizeof(struct udphdr));
+		udph->source = sport;
+		udph->dest = dport;
+		udph->len = htons(sizeof(struct udphdr));
+		udph->check = 0;
+		break;
+	}
+	case IPPROTO_TCP: {
+		struct tcphdr *tcph;
+
+		tcph = skb_put_zero(skb, sizeof(struct tcphdr));
+		tcph->source	= sport;
+		tcph->dest	= dport;
+		tcph->doff	= sizeof(struct tcphdr) / 4;
+		tcph->rst = 1;
+		tcph->check = ~tcp_v4_check(sizeof(struct tcphdr),
+					    src, dst, 0);
+		break;
+	}
+	case IPPROTO_ICMP: {
+		struct icmphdr *icmph;
+
+		icmph = skb_put_zero(skb, sizeof(struct icmphdr));
+		icmph->type = ICMP_ECHO;
+		icmph->code = 0;
+	}
+	}
+
+	return skb;
+}
+
+static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
+			     struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(in_skb->sk);
+	struct nlattr *tb[RTA_MAX+1];
+	u32 table_id = RT_TABLE_MAIN;
+	__be16 sport = 0, dport = 0;
+	struct fib_result res = {};
+	u8 ip_proto = IPPROTO_UDP;
+	struct rtable *rt = NULL;
+	struct sk_buff *skb;
+	struct rtmsg *rtm;
+	struct flowi4 fl4;
+	__be32 dst = 0;
+	__be32 src = 0;
+	kuid_t uid;
+	u32 iif;
+	int err;
+	int mark;
+
+	err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_ipv4_policy,
+			  extack);
+	if (err < 0)
+		return err;
+
+	rtm = nlmsg_data(nlh);
+	src = tb[RTA_SRC] ? nla_get_in_addr(tb[RTA_SRC]) : 0;
+	dst = tb[RTA_DST] ? nla_get_in_addr(tb[RTA_DST]) : 0;
+	iif = tb[RTA_IIF] ? nla_get_u32(tb[RTA_IIF]) : 0;
+	mark = tb[RTA_MARK] ? nla_get_u32(tb[RTA_MARK]) : 0;
+	if (tb[RTA_UID])
+		uid = make_kuid(current_user_ns(), nla_get_u32(tb[RTA_UID]));
+	else
+		uid = (iif ? INVALID_UID : current_uid());
+
+	if (tb[RTA_IP_PROTO]) {
+		err = rtm_getroute_parse_ip_proto(tb[RTA_IP_PROTO],
+						  &ip_proto, AF_INET, extack);
+		if (err)
+			return err;
+	}
+
+	if (tb[RTA_SPORT])
+		sport = nla_get_be16(tb[RTA_SPORT]);
+
+	if (tb[RTA_DPORT])
+		dport = nla_get_be16(tb[RTA_DPORT]);
+
+	skb = inet_rtm_getroute_build_skb(src, dst, ip_proto, sport, dport);
+	if (!skb)
+		return -ENOBUFS;
+
+	memset(&fl4, 0, sizeof(fl4));
+	fl4.daddr = dst;
+	fl4.saddr = src;
+	fl4.flowi4_tos = rtm->rtm_tos & IPTOS_RT_MASK;
+	fl4.flowi4_oif = tb[RTA_OIF] ? nla_get_u32(tb[RTA_OIF]) : 0;
+	fl4.flowi4_mark = mark;
+	fl4.flowi4_uid = uid;
+	if (sport)
+		fl4.fl4_sport = sport;
+	if (dport)
+		fl4.fl4_dport = dport;
+	fl4.flowi4_proto = ip_proto;
+
+	rcu_read_lock();
+
+	if (iif) {
+		struct net_device *dev;
+
+		dev = dev_get_by_index_rcu(net, iif);
+		if (!dev) {
+			err = -ENODEV;
+			goto errout_rcu;
+		}
+
+		fl4.flowi4_iif = iif; /* for rt_fill_info */
+		skb->dev	= dev;
+		skb->mark	= mark;
+		err = ip_route_input_rcu(skb, dst, src,
+					 rtm->rtm_tos & IPTOS_RT_MASK, dev,
+					 &res);
+
+		rt = skb_rtable(skb);
+		if (err == 0 && rt->dst.error)
+			err = -rt->dst.error;
+	} else {
+		fl4.flowi4_iif = LOOPBACK_IFINDEX;
+		rt = ip_route_output_key_hash_rcu(net, &fl4, &res, skb);
+		err = 0;
+		if (IS_ERR(rt))
+			err = PTR_ERR(rt);
+		else
+			skb_dst_set(skb, &rt->dst);
+	}
+
+	if (err)
+		goto errout_rcu;
+
+	if (rtm->rtm_flags & RTM_F_NOTIFY)
+		rt->rt_flags |= RTCF_NOTIFY;
+
+	if (rtm->rtm_flags & RTM_F_LOOKUP_TABLE)
+		table_id = res.table ? res.table->tb_id : 0;
+
+	/* reset skb for netlink reply msg */
+	skb_trim(skb, 0);
+	skb_reset_network_header(skb);
+	skb_reset_transport_header(skb);
+	skb_reset_mac_header(skb);
+
+	if (rtm->rtm_flags & RTM_F_FIB_MATCH) {
+		if (!res.fi) {
+			err = fib_props[res.type].error;
+			if (!err)
+				err = -EHOSTUNREACH;
+			goto errout_rcu;
+		}
+		err = fib_dump_info(skb, NETLINK_CB(in_skb).portid,
+				    nlh->nlmsg_seq, RTM_NEWROUTE, table_id,
+				    rt->rt_type, res.prefix, res.prefixlen,
+				    fl4.flowi4_tos, res.fi, 0);
+	} else {
+		err = rt_fill_info(net, dst, src, rt, table_id, &fl4, skb,
+				   NETLINK_CB(in_skb).portid, nlh->nlmsg_seq);
+	}
+	if (err < 0)
+		goto errout_rcu;
+
+	rcu_read_unlock();
+
+	err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
+
+errout_free:
+	return err;
+errout_rcu:
+	rcu_read_unlock();
+	kfree_skb(skb);
+	goto errout_free;
+}
+
+void ip_rt_multicast_event(struct in_device *in_dev)
+{
+	rt_cache_flush(dev_net(in_dev->dev));
+}
+
+#ifdef CONFIG_SYSCTL
+static int ip_rt_gc_interval __read_mostly  = 60 * HZ;
+static int ip_rt_gc_min_interval __read_mostly	= HZ / 2;
+static int ip_rt_gc_elasticity __read_mostly	= 8;
+static int ip_min_valid_pmtu __read_mostly	= IPV4_MIN_MTU;
+
+static int ipv4_sysctl_rtcache_flush(struct ctl_table *__ctl, int write,
+					void __user *buffer,
+					size_t *lenp, loff_t *ppos)
+{
+	struct net *net = (struct net *)__ctl->extra1;
+
+	if (write) {
+		rt_cache_flush(net);
+		fnhe_genid_bump(net);
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static struct ctl_table ipv4_route_table[] = {
+	{
+		.procname	= "gc_thresh",
+		.data		= &ipv4_dst_ops.gc_thresh,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "max_size",
+		.data		= &ip_rt_max_size,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		/*  Deprecated. Use gc_min_interval_ms */
+
+		.procname	= "gc_min_interval",
+		.data		= &ip_rt_gc_min_interval,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{
+		.procname	= "gc_min_interval_ms",
+		.data		= &ip_rt_gc_min_interval,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_ms_jiffies,
+	},
+	{
+		.procname	= "gc_timeout",
+		.data		= &ip_rt_gc_timeout,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{
+		.procname	= "gc_interval",
+		.data		= &ip_rt_gc_interval,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{
+		.procname	= "redirect_load",
+		.data		= &ip_rt_redirect_load,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "redirect_number",
+		.data		= &ip_rt_redirect_number,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "redirect_silence",
+		.data		= &ip_rt_redirect_silence,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "error_cost",
+		.data		= &ip_rt_error_cost,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "error_burst",
+		.data		= &ip_rt_error_burst,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "gc_elasticity",
+		.data		= &ip_rt_gc_elasticity,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "mtu_expires",
+		.data		= &ip_rt_mtu_expires,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{
+		.procname	= "min_pmtu",
+		.data		= &ip_rt_min_pmtu,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &ip_min_valid_pmtu,
+	},
+	{
+		.procname	= "min_adv_mss",
+		.data		= &ip_rt_min_advmss,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{ }
+};
+
+static struct ctl_table ipv4_route_flush_table[] = {
+	{
+		.procname	= "flush",
+		.maxlen		= sizeof(int),
+		.mode		= 0200,
+		.proc_handler	= ipv4_sysctl_rtcache_flush,
+	},
+	{ },
+};
+
+static __net_init int sysctl_route_net_init(struct net *net)
+{
+	struct ctl_table *tbl;
+
+	tbl = ipv4_route_flush_table;
+	if (!net_eq(net, &init_net)) {
+		tbl = kmemdup(tbl, sizeof(ipv4_route_flush_table), GFP_KERNEL);
+		if (!tbl)
+			goto err_dup;
+
+		/* Don't export sysctls to unprivileged users */
+		if (net->user_ns != &init_user_ns)
+			tbl[0].procname = NULL;
+	}
+	tbl[0].extra1 = net;
+
+	net->ipv4.route_hdr = register_net_sysctl(net, "net/ipv4/route", tbl);
+	if (!net->ipv4.route_hdr)
+		goto err_reg;
+	return 0;
+
+err_reg:
+	if (tbl != ipv4_route_flush_table)
+		kfree(tbl);
+err_dup:
+	return -ENOMEM;
+}
+
+static __net_exit void sysctl_route_net_exit(struct net *net)
+{
+	struct ctl_table *tbl;
+
+	tbl = net->ipv4.route_hdr->ctl_table_arg;
+	unregister_net_sysctl_table(net->ipv4.route_hdr);
+	BUG_ON(tbl == ipv4_route_flush_table);
+	kfree(tbl);
+}
+
+static __net_initdata struct pernet_operations sysctl_route_ops = {
+	.init = sysctl_route_net_init,
+	.exit = sysctl_route_net_exit,
+};
+#endif
+
+static __net_init int rt_genid_init(struct net *net)
+{
+	atomic_set(&net->ipv4.rt_genid, 0);
+	atomic_set(&net->fnhe_genid, 0);
+	atomic_set(&net->ipv4.dev_addr_genid, get_random_int());
+	return 0;
+}
+
+static __net_initdata struct pernet_operations rt_genid_ops = {
+	.init = rt_genid_init,
+};
+
+static int __net_init ipv4_inetpeer_init(struct net *net)
+{
+	struct inet_peer_base *bp = kmalloc(sizeof(*bp), GFP_KERNEL);
+
+	if (!bp)
+		return -ENOMEM;
+	inet_peer_base_init(bp);
+	net->ipv4.peers = bp;
+	return 0;
+}
+
+static void __net_exit ipv4_inetpeer_exit(struct net *net)
+{
+	struct inet_peer_base *bp = net->ipv4.peers;
+
+	net->ipv4.peers = NULL;
+	inetpeer_invalidate_tree(bp);
+	kfree(bp);
+}
+
+static __net_initdata struct pernet_operations ipv4_inetpeer_ops = {
+	.init	=	ipv4_inetpeer_init,
+	.exit	=	ipv4_inetpeer_exit,
+};
+
+#ifdef CONFIG_IP_ROUTE_CLASSID
+struct ip_rt_acct __percpu *ip_rt_acct __read_mostly;
+#endif /* CONFIG_IP_ROUTE_CLASSID */
+
+int __init ip_rt_init(void)
+{
+	void *idents_hash;
+	int cpu;
+
+	/* For modern hosts, this will use 2 MB of memory */
+	idents_hash = alloc_large_system_hash("IP idents",
+					      sizeof(*ip_idents) + sizeof(*ip_tstamps),
+					      0,
+					      16, /* one bucket per 64 KB */
+					      HASH_ZERO,
+					      NULL,
+					      &ip_idents_mask,
+					      2048,
+					      256*1024);
+
+	ip_idents = idents_hash;
+
+	prandom_bytes(ip_idents, (ip_idents_mask + 1) * sizeof(*ip_idents));
+
+	ip_tstamps = idents_hash + (ip_idents_mask + 1) * sizeof(*ip_idents);
+
+	for_each_possible_cpu(cpu) {
+		struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
+
+		INIT_LIST_HEAD(&ul->head);
+		spin_lock_init(&ul->lock);
+	}
+#ifdef CONFIG_IP_ROUTE_CLASSID
+	ip_rt_acct = __alloc_percpu(256 * sizeof(struct ip_rt_acct), __alignof__(struct ip_rt_acct));
+	if (!ip_rt_acct)
+		panic("IP: failed to allocate ip_rt_acct\n");
+#endif
+
+	ipv4_dst_ops.kmem_cachep =
+		kmem_cache_create("ip_dst_cache", sizeof(struct rtable), 0,
+				  SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
+
+	ipv4_dst_blackhole_ops.kmem_cachep = ipv4_dst_ops.kmem_cachep;
+
+	if (dst_entries_init(&ipv4_dst_ops) < 0)
+		panic("IP: failed to allocate ipv4_dst_ops counter\n");
+
+	if (dst_entries_init(&ipv4_dst_blackhole_ops) < 0)
+		panic("IP: failed to allocate ipv4_dst_blackhole_ops counter\n");
+
+	ipv4_dst_ops.gc_thresh = ~0;
+	ip_rt_max_size = INT_MAX;
+
+	devinet_init();
+	ip_fib_init();
+
+	if (ip_rt_proc_init())
+		pr_err("Unable to create route proc files\n");
+#ifdef CONFIG_XFRM
+	xfrm_init();
+	xfrm4_init();
+#endif
+	rtnl_register(PF_INET, RTM_GETROUTE, inet_rtm_getroute, NULL,
+		      RTNL_FLAG_DOIT_UNLOCKED);
+
+#ifdef CONFIG_SYSCTL
+	register_pernet_subsys(&sysctl_route_ops);
+#endif
+	register_pernet_subsys(&rt_genid_ops);
+	register_pernet_subsys(&ipv4_inetpeer_ops);
+	return 0;
+}
+
+#ifdef CONFIG_SYSCTL
+/*
+ * We really need to sanitize the damn ipv4 init order, then all
+ * this nonsense will go away.
+ */
+void __init ip_static_sysctl_init(void)
+{
+	register_net_sysctl(&init_net, "net/ipv4/route", ipv4_route_table);
+}
+#endif