/*
 *	Linux INET6 implementation
 *	FIB front-end.
 *
 *	Authors:
 *	Pedro Roque		<roque@di.fc.ul.pt>
 *
 *	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.
 */

/*	Changes:
 *
 *	YOSHIFUJI Hideaki @USAGI
 *		reworked default router selection.
 *		- respect outgoing interface
 *		- select from (probably) reachable routers (i.e.
 *		routers in REACHABLE, STALE, DELAY or PROBE states).
 *		- always select the same router if it is (probably)
 *		reachable.  otherwise, round-robin the list.
 *	Ville Nuorvala
 *		Fixed routing subtrees.
 */

#define pr_fmt(fmt) "IPv6: " fmt

#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/types.h>
#include <linux/times.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/route.h>
#include <linux/netdevice.h>
#include <linux/in6.h>
#include <linux/mroute6.h>
#include <linux/init.h>
#include <linux/if_arp.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/nsproxy.h>
#include <linux/slab.h>
#include <linux/jhash.h>
#include <net/net_namespace.h>
#include <net/snmp.h>
#include <net/ipv6.h>
#include <net/ip6_fib.h>
#include <net/ip6_route.h>
#include <net/ndisc.h>
#include <net/addrconf.h>
#include <net/tcp.h>
#include <linux/rtnetlink.h>
#include <net/dst.h>
#include <net/dst_metadata.h>
#include <net/xfrm.h>
#include <net/netevent.h>
#include <net/netlink.h>
#include <net/nexthop.h>
#include <net/lwtunnel.h>
#include <net/ip_tunnels.h>
#include <net/l3mdev.h>
#include <trace/events/fib6.h>

#include <linux/uaccess.h>

#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
#endif

enum rt6_nud_state {
	RT6_NUD_FAIL_HARD = -3,
	RT6_NUD_FAIL_PROBE = -2,
	RT6_NUD_FAIL_DO_RR = -1,
	RT6_NUD_SUCCEED = 1
};

static void ip6_rt_copy_init(struct rt6_info *rt, struct rt6_info *ort);
static struct dst_entry	*ip6_dst_check(struct dst_entry *dst, u32 cookie);
static unsigned int	 ip6_default_advmss(const struct dst_entry *dst);
static unsigned int	 ip6_mtu(const struct dst_entry *dst);
static struct dst_entry *ip6_negative_advice(struct dst_entry *);
static void		ip6_dst_destroy(struct dst_entry *);
static void		ip6_dst_ifdown(struct dst_entry *,
				       struct net_device *dev, int how);
static int		 ip6_dst_gc(struct dst_ops *ops);

static int		ip6_pkt_discard(struct sk_buff *skb);
static int		ip6_pkt_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
static int		ip6_pkt_prohibit(struct sk_buff *skb);
static int		ip6_pkt_prohibit_out(struct net *net, struct sock *sk, struct sk_buff *skb);
static void		ip6_link_failure(struct sk_buff *skb);
static void		ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
					   struct sk_buff *skb, u32 mtu);
static void		rt6_do_redirect(struct dst_entry *dst, struct sock *sk,
					struct sk_buff *skb);
static void		rt6_dst_from_metrics_check(struct rt6_info *rt);
static int rt6_score_route(struct rt6_info *rt, int oif, int strict);
static size_t rt6_nlmsg_size(struct rt6_info *rt);
static int rt6_fill_node(struct net *net,
			 struct sk_buff *skb, struct rt6_info *rt,
			 struct in6_addr *dst, struct in6_addr *src,
			 int iif, int type, u32 portid, u32 seq,
			 unsigned int flags);
static struct rt6_info *rt6_find_cached_rt(struct rt6_info *rt,
					   struct in6_addr *daddr,
					   struct in6_addr *saddr);

#ifdef CONFIG_IPV6_ROUTE_INFO
static struct rt6_info *rt6_add_route_info(struct net *net,
					   const struct in6_addr *prefix, int prefixlen,
					   const struct in6_addr *gwaddr,
					   struct net_device *dev,
					   unsigned int pref);
static struct rt6_info *rt6_get_route_info(struct net *net,
					   const struct in6_addr *prefix, int prefixlen,
					   const struct in6_addr *gwaddr,
					   struct net_device *dev);
#endif

struct uncached_list {
	spinlock_t		lock;
	struct list_head	head;
};

static DEFINE_PER_CPU_ALIGNED(struct uncached_list, rt6_uncached_list);

void rt6_uncached_list_add(struct rt6_info *rt)
{
	struct uncached_list *ul = raw_cpu_ptr(&rt6_uncached_list);

	rt->rt6i_uncached_list = ul;

	spin_lock_bh(&ul->lock);
	list_add_tail(&rt->rt6i_uncached, &ul->head);
	spin_unlock_bh(&ul->lock);
}

void rt6_uncached_list_del(struct rt6_info *rt)
{
	if (!list_empty(&rt->rt6i_uncached)) {
		struct uncached_list *ul = rt->rt6i_uncached_list;
		struct net *net = dev_net(rt->dst.dev);

		spin_lock_bh(&ul->lock);
		list_del(&rt->rt6i_uncached);
		atomic_dec(&net->ipv6.rt6_stats->fib_rt_uncache);
		spin_unlock_bh(&ul->lock);
	}
}

static void rt6_uncached_list_flush_dev(struct net *net, struct net_device *dev)
{
	struct net_device *loopback_dev = net->loopback_dev;
	int cpu;

	if (dev == loopback_dev)
		return;

	for_each_possible_cpu(cpu) {
		struct uncached_list *ul = per_cpu_ptr(&rt6_uncached_list, cpu);
		struct rt6_info *rt;

		spin_lock_bh(&ul->lock);
		list_for_each_entry(rt, &ul->head, rt6i_uncached) {
			struct inet6_dev *rt_idev = rt->rt6i_idev;
			struct net_device *rt_dev = rt->dst.dev;

			if (rt_idev->dev == dev) {
				rt->rt6i_idev = in6_dev_get(loopback_dev);
				in6_dev_put(rt_idev);
			}

			if (rt_dev == dev) {
				rt->dst.dev = loopback_dev;
				dev_hold(rt->dst.dev);
				dev_put(rt_dev);
			}
		}
		spin_unlock_bh(&ul->lock);
	}
}

static u32 *rt6_pcpu_cow_metrics(struct rt6_info *rt)
{
	return dst_metrics_write_ptr(&rt->from->dst);
}

static u32 *ipv6_cow_metrics(struct dst_entry *dst, unsigned long old)
{
	struct rt6_info *rt = (struct rt6_info *)dst;

	if (rt->rt6i_flags & RTF_PCPU)
		return rt6_pcpu_cow_metrics(rt);
	else if (rt->rt6i_flags & RTF_CACHE)
		return NULL;
	else
		return dst_cow_metrics_generic(dst, old);
}

static inline const void *choose_neigh_daddr(struct rt6_info *rt,
					     struct sk_buff *skb,
					     const void *daddr)
{
	struct in6_addr *p = &rt->rt6i_gateway;

	if (!ipv6_addr_any(p))
		return (const void *) p;
	else if (skb)
		return &ipv6_hdr(skb)->daddr;
	return daddr;
}

static struct neighbour *ip6_neigh_lookup(const struct dst_entry *dst,
					  struct sk_buff *skb,
					  const void *daddr)
{
	struct rt6_info *rt = (struct rt6_info *) dst;
	struct neighbour *n;

	daddr = choose_neigh_daddr(rt, skb, daddr);
	n = __ipv6_neigh_lookup(dst->dev, daddr);
	if (n)
		return n;
	return neigh_create(&nd_tbl, daddr, dst->dev);
}

static void ip6_confirm_neigh(const struct dst_entry *dst, const void *daddr)
{
	struct net_device *dev = dst->dev;
	struct rt6_info *rt = (struct rt6_info *)dst;

	daddr = choose_neigh_daddr(rt, NULL, daddr);
	if (!daddr)
		return;
	if (dev->flags & (IFF_NOARP | IFF_LOOPBACK))
		return;
	if (ipv6_addr_is_multicast((const struct in6_addr *)daddr))
		return;
	__ipv6_confirm_neigh(dev, daddr);
}

static struct dst_ops ip6_dst_ops_template = {
	.family			=	AF_INET6,
	.gc			=	ip6_dst_gc,
	.gc_thresh		=	1024,
	.check			=	ip6_dst_check,
	.default_advmss		=	ip6_default_advmss,
	.mtu			=	ip6_mtu,
	.cow_metrics		=	ipv6_cow_metrics,
	.destroy		=	ip6_dst_destroy,
	.ifdown			=	ip6_dst_ifdown,
	.negative_advice	=	ip6_negative_advice,
	.link_failure		=	ip6_link_failure,
	.update_pmtu		=	ip6_rt_update_pmtu,
	.redirect		=	rt6_do_redirect,
	.local_out		=	__ip6_local_out,
	.neigh_lookup		=	ip6_neigh_lookup,
	.confirm_neigh		=	ip6_confirm_neigh,
};

static unsigned int ip6_blackhole_mtu(const struct dst_entry *dst)
{
	unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);

	return mtu ? : dst->dev->mtu;
}

static void ip6_rt_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
					 struct sk_buff *skb, u32 mtu)
{
}

static void ip6_rt_blackhole_redirect(struct dst_entry *dst, struct sock *sk,
				      struct sk_buff *skb)
{
}

static struct dst_ops ip6_dst_blackhole_ops = {
	.family			=	AF_INET6,
	.destroy		=	ip6_dst_destroy,
	.check			=	ip6_dst_check,
	.mtu			=	ip6_blackhole_mtu,
	.default_advmss		=	ip6_default_advmss,
	.update_pmtu		=	ip6_rt_blackhole_update_pmtu,
	.redirect		=	ip6_rt_blackhole_redirect,
	.cow_metrics		=	dst_cow_metrics_generic,
	.neigh_lookup		=	ip6_neigh_lookup,
};

static const u32 ip6_template_metrics[RTAX_MAX] = {
	[RTAX_HOPLIMIT - 1] = 0,
};

static const struct rt6_info ip6_null_entry_template = {
	.dst = {
		.__refcnt	= ATOMIC_INIT(1),
		.__use		= 1,
		.obsolete	= DST_OBSOLETE_FORCE_CHK,
		.error		= -ENETUNREACH,
		.input		= ip6_pkt_discard,
		.output		= ip6_pkt_discard_out,
	},
	.rt6i_flags	= (RTF_REJECT | RTF_NONEXTHOP),
	.rt6i_protocol  = RTPROT_KERNEL,
	.rt6i_metric	= ~(u32) 0,
	.rt6i_ref	= ATOMIC_INIT(1),
};

#ifdef CONFIG_IPV6_MULTIPLE_TABLES

static const struct rt6_info ip6_prohibit_entry_template = {
	.dst = {
		.__refcnt	= ATOMIC_INIT(1),
		.__use		= 1,
		.obsolete	= DST_OBSOLETE_FORCE_CHK,
		.error		= -EACCES,
		.input		= ip6_pkt_prohibit,
		.output		= ip6_pkt_prohibit_out,
	},
	.rt6i_flags	= (RTF_REJECT | RTF_NONEXTHOP),
	.rt6i_protocol  = RTPROT_KERNEL,
	.rt6i_metric	= ~(u32) 0,
	.rt6i_ref	= ATOMIC_INIT(1),
};

static const struct rt6_info ip6_blk_hole_entry_template = {
	.dst = {
		.__refcnt	= ATOMIC_INIT(1),
		.__use		= 1,
		.obsolete	= DST_OBSOLETE_FORCE_CHK,
		.error		= -EINVAL,
		.input		= dst_discard,
		.output		= dst_discard_out,
	},
	.rt6i_flags	= (RTF_REJECT | RTF_NONEXTHOP),
	.rt6i_protocol  = RTPROT_KERNEL,
	.rt6i_metric	= ~(u32) 0,
	.rt6i_ref	= ATOMIC_INIT(1),
};

#endif

static void rt6_info_init(struct rt6_info *rt)
{
	struct dst_entry *dst = &rt->dst;

	memset(dst + 1, 0, sizeof(*rt) - sizeof(*dst));
	INIT_LIST_HEAD(&rt->rt6i_siblings);
	INIT_LIST_HEAD(&rt->rt6i_uncached);
}

/* allocate dst with ip6_dst_ops */
static struct rt6_info *__ip6_dst_alloc(struct net *net,
					struct net_device *dev,
					int flags)
{
	struct rt6_info *rt = dst_alloc(&net->ipv6.ip6_dst_ops, dev,
					1, DST_OBSOLETE_FORCE_CHK, flags);

	if (rt) {
		rt6_info_init(rt);
		atomic_inc(&net->ipv6.rt6_stats->fib_rt_alloc);
	}

	return rt;
}

struct rt6_info *ip6_dst_alloc(struct net *net,
			       struct net_device *dev,
			       int flags)
{
	struct rt6_info *rt = __ip6_dst_alloc(net, dev, flags);

	if (rt) {
		rt->rt6i_pcpu = alloc_percpu_gfp(struct rt6_info *, GFP_ATOMIC);
		if (!rt->rt6i_pcpu) {
			dst_release_immediate(&rt->dst);
			return NULL;
		}
	}

	return rt;
}
EXPORT_SYMBOL(ip6_dst_alloc);

static void ip6_dst_destroy(struct dst_entry *dst)
{
	struct rt6_info *rt = (struct rt6_info *)dst;
	struct rt6_exception_bucket *bucket;
	struct rt6_info *from = rt->from;
	struct inet6_dev *idev;

	dst_destroy_metrics_generic(dst);
	free_percpu(rt->rt6i_pcpu);
	rt6_uncached_list_del(rt);

	idev = rt->rt6i_idev;
	if (idev) {
		rt->rt6i_idev = NULL;
		in6_dev_put(idev);
	}
	bucket = rcu_dereference_protected(rt->rt6i_exception_bucket, 1);
	if (bucket) {
		rt->rt6i_exception_bucket = NULL;
		kfree(bucket);
	}

	rt->from = NULL;
	dst_release(&from->dst);
}

static void ip6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
			   int how)
{
	struct rt6_info *rt = (struct rt6_info *)dst;
	struct inet6_dev *idev = rt->rt6i_idev;
	struct net_device *loopback_dev =
		dev_net(dev)->loopback_dev;

	if (idev && idev->dev != loopback_dev) {
		struct inet6_dev *loopback_idev = in6_dev_get(loopback_dev);
		if (loopback_idev) {
			rt->rt6i_idev = loopback_idev;
			in6_dev_put(idev);
		}
	}
}

static bool __rt6_check_expired(const struct rt6_info *rt)
{
	if (rt->rt6i_flags & RTF_EXPIRES)
		return time_after(jiffies, rt->dst.expires);
	else
		return false;
}

static bool rt6_check_expired(const struct rt6_info *rt)
{
	if (rt->rt6i_flags & RTF_EXPIRES) {
		if (time_after(jiffies, rt->dst.expires))
			return true;
	} else if (rt->from) {
		return rt->dst.obsolete != DST_OBSOLETE_FORCE_CHK ||
			rt6_check_expired(rt->from);
	}
	return false;
}

static struct rt6_info *rt6_multipath_select(struct rt6_info *match,
					     struct flowi6 *fl6, int oif,
					     int strict)
{
	struct rt6_info *sibling, *next_sibling;

	/* We might have already computed the hash for ICMPv6 errors. In such
	 * case it will always be non-zero. Otherwise now is the time to do it.
	 */
	if (!fl6->mp_hash)
		fl6->mp_hash = rt6_multipath_hash(fl6, NULL);

	if (fl6->mp_hash <= atomic_read(&match->rt6i_nh_upper_bound))
		return match;

	list_for_each_entry_safe(sibling, next_sibling, &match->rt6i_siblings,
				 rt6i_siblings) {
		if (fl6->mp_hash > atomic_read(&sibling->rt6i_nh_upper_bound))
			continue;
		if (rt6_score_route(sibling, oif, strict) < 0)
			break;
		match = sibling;
		break;
	}

	return match;
}

/*
 *	Route lookup. rcu_read_lock() should be held.
 */

static inline struct rt6_info *rt6_device_match(struct net *net,
						    struct rt6_info *rt,
						    const struct in6_addr *saddr,
						    int oif,
						    int flags)
{
	struct rt6_info *local = NULL;
	struct rt6_info *sprt;

	if (!oif && ipv6_addr_any(saddr) && !(rt->rt6i_nh_flags & RTNH_F_DEAD))
		return rt;

	for (sprt = rt; sprt; sprt = rcu_dereference(sprt->rt6_next)) {
		struct net_device *dev = sprt->dst.dev;

		if (sprt->rt6i_nh_flags & RTNH_F_DEAD)
			continue;

		if (oif) {
			if (dev->ifindex == oif)
				return sprt;
			if (dev->flags & IFF_LOOPBACK) {
				if (!sprt->rt6i_idev ||
				    sprt->rt6i_idev->dev->ifindex != oif) {
					if (flags & RT6_LOOKUP_F_IFACE)
						continue;
					if (local &&
					    local->rt6i_idev->dev->ifindex == oif)
						continue;
				}
				local = sprt;
			}
		} else {
			if (ipv6_chk_addr(net, saddr, dev,
					  flags & RT6_LOOKUP_F_IFACE))
				return sprt;
		}
	}

	if (oif) {
		if (local)
			return local;

		if (flags & RT6_LOOKUP_F_IFACE)
			return net->ipv6.ip6_null_entry;
	}

	return rt->rt6i_nh_flags & RTNH_F_DEAD ? net->ipv6.ip6_null_entry : rt;
}

#ifdef CONFIG_IPV6_ROUTER_PREF
struct __rt6_probe_work {
	struct work_struct work;
	struct in6_addr target;
	struct net_device *dev;
};

static void rt6_probe_deferred(struct work_struct *w)
{
	struct in6_addr mcaddr;
	struct __rt6_probe_work *work =
		container_of(w, struct __rt6_probe_work, work);

	addrconf_addr_solict_mult(&work->target, &mcaddr);
	ndisc_send_ns(work->dev, &work->target, &mcaddr, NULL, 0);
	dev_put(work->dev);
	kfree(work);
}

static void rt6_probe(struct rt6_info *rt)
{
	struct __rt6_probe_work *work;
	struct neighbour *neigh;
	/*
	 * Okay, this does not seem to be appropriate
	 * for now, however, we need to check if it
	 * is really so; aka Router Reachability Probing.
	 *
	 * Router Reachability Probe MUST be rate-limited
	 * to no more than one per minute.
	 */
	if (!rt || !(rt->rt6i_flags & RTF_GATEWAY))
		return;
	rcu_read_lock_bh();
	neigh = __ipv6_neigh_lookup_noref(rt->dst.dev, &rt->rt6i_gateway);
	if (neigh) {
		if (neigh->nud_state & NUD_VALID)
			goto out;

		work = NULL;
		write_lock(&neigh->lock);
		if (!(neigh->nud_state & NUD_VALID) &&
		    time_after(jiffies,
			       neigh->updated +
			       rt->rt6i_idev->cnf.rtr_probe_interval)) {
			work = kmalloc(sizeof(*work), GFP_ATOMIC);
			if (work)
				__neigh_set_probe_once(neigh);
		}
		write_unlock(&neigh->lock);
	} else {
		work = kmalloc(sizeof(*work), GFP_ATOMIC);
	}

	if (work) {
		INIT_WORK(&work->work, rt6_probe_deferred);
		work->target = rt->rt6i_gateway;
		dev_hold(rt->dst.dev);
		work->dev = rt->dst.dev;
		schedule_work(&work->work);
	}

out:
	rcu_read_unlock_bh();
}
#else
static inline void rt6_probe(struct rt6_info *rt)
{
}
#endif

/*
 * Default Router Selection (RFC 2461 6.3.6)
 */
static inline int rt6_check_dev(struct rt6_info *rt, int oif)
{
	struct net_device *dev = rt->dst.dev;
	if (!oif || dev->ifindex == oif)
		return 2;
	if ((dev->flags & IFF_LOOPBACK) &&
	    rt->rt6i_idev && rt->rt6i_idev->dev->ifindex == oif)
		return 1;
	return 0;
}

static inline enum rt6_nud_state rt6_check_neigh(struct rt6_info *rt)
{
	struct neighbour *neigh;
	enum rt6_nud_state ret = RT6_NUD_FAIL_HARD;

	if (rt->rt6i_flags & RTF_NONEXTHOP ||
	    !(rt->rt6i_flags & RTF_GATEWAY))
		return RT6_NUD_SUCCEED;

	rcu_read_lock_bh();
	neigh = __ipv6_neigh_lookup_noref(rt->dst.dev, &rt->rt6i_gateway);
	if (neigh) {
		read_lock(&neigh->lock);
		if (neigh->nud_state & NUD_VALID)
			ret = RT6_NUD_SUCCEED;
#ifdef CONFIG_IPV6_ROUTER_PREF
		else if (!(neigh->nud_state & NUD_FAILED))
			ret = RT6_NUD_SUCCEED;
		else
			ret = RT6_NUD_FAIL_PROBE;
#endif
		read_unlock(&neigh->lock);
	} else {
		ret = IS_ENABLED(CONFIG_IPV6_ROUTER_PREF) ?
		      RT6_NUD_SUCCEED : RT6_NUD_FAIL_DO_RR;
	}
	rcu_read_unlock_bh();

	return ret;
}

static int rt6_score_route(struct rt6_info *rt, int oif,
			   int strict)
{
	int m;

	m = rt6_check_dev(rt, oif);
	if (!m && (strict & RT6_LOOKUP_F_IFACE))
		return RT6_NUD_FAIL_HARD;
#ifdef CONFIG_IPV6_ROUTER_PREF
	m |= IPV6_DECODE_PREF(IPV6_EXTRACT_PREF(rt->rt6i_flags)) << 2;
#endif
	if (strict & RT6_LOOKUP_F_REACHABLE) {
		int n = rt6_check_neigh(rt);
		if (n < 0)
			return n;
	}
	return m;
}

static struct rt6_info *find_match(struct rt6_info *rt, int oif, int strict,
				   int *mpri, struct rt6_info *match,
				   bool *do_rr)
{
	int m;
	bool match_do_rr = false;
	struct inet6_dev *idev = rt->rt6i_idev;

	if (rt->rt6i_nh_flags & RTNH_F_DEAD)
		goto out;

	if (idev->cnf.ignore_routes_with_linkdown &&
	    rt->rt6i_nh_flags & RTNH_F_LINKDOWN &&
	    !(strict & RT6_LOOKUP_F_IGNORE_LINKSTATE))
		goto out;

	if (rt6_check_expired(rt))
		goto out;

	m = rt6_score_route(rt, oif, strict);
	if (m == RT6_NUD_FAIL_DO_RR) {
		match_do_rr = true;
		m = 0; /* lowest valid score */
	} else if (m == RT6_NUD_FAIL_HARD) {
		goto out;
	}

	if (strict & RT6_LOOKUP_F_REACHABLE)
		rt6_probe(rt);

	/* note that m can be RT6_NUD_FAIL_PROBE at this point */
	if (m > *mpri) {
		*do_rr = match_do_rr;
		*mpri = m;
		match = rt;
	}
out:
	return match;
}

static struct rt6_info *find_rr_leaf(struct fib6_node *fn,
				     struct rt6_info *leaf,
				     struct rt6_info *rr_head,
				     u32 metric, int oif, int strict,
				     bool *do_rr)
{
	struct rt6_info *rt, *match, *cont;
	int mpri = -1;

	match = NULL;
	cont = NULL;
	for (rt = rr_head; rt; rt = rcu_dereference(rt->rt6_next)) {
		if (rt->rt6i_metric != metric) {
			cont = rt;
			break;
		}

		match = find_match(rt, oif, strict, &mpri, match, do_rr);
	}

	for (rt = leaf; rt && rt != rr_head;
	     rt = rcu_dereference(rt->rt6_next)) {
		if (rt->rt6i_metric != metric) {
			cont = rt;
			break;
		}

		match = find_match(rt, oif, strict, &mpri, match, do_rr);
	}

	if (match || !cont)
		return match;

	for (rt = cont; rt; rt = rcu_dereference(rt->rt6_next))
		match = find_match(rt, oif, strict, &mpri, match, do_rr);

	return match;
}

static struct rt6_info *rt6_select(struct net *net, struct fib6_node *fn,
				   int oif, int strict)
{
	struct rt6_info *leaf = rcu_dereference(fn->leaf);
	struct rt6_info *match, *rt0;
	bool do_rr = false;
	int key_plen;

	if (!leaf || leaf == net->ipv6.ip6_null_entry)
		return net->ipv6.ip6_null_entry;

	rt0 = rcu_dereference(fn->rr_ptr);
	if (!rt0)
		rt0 = leaf;

	/* Double check to make sure fn is not an intermediate node
	 * and fn->leaf does not points to its child's leaf
	 * (This might happen if all routes under fn are deleted from
	 * the tree and fib6_repair_tree() is called on the node.)
	 */
	key_plen = rt0->rt6i_dst.plen;
#ifdef CONFIG_IPV6_SUBTREES
	if (rt0->rt6i_src.plen)
		key_plen = rt0->rt6i_src.plen;
#endif
	if (fn->fn_bit != key_plen)
		return net->ipv6.ip6_null_entry;

	match = find_rr_leaf(fn, leaf, rt0, rt0->rt6i_metric, oif, strict,
			     &do_rr);

	if (do_rr) {
		struct rt6_info *next = rcu_dereference(rt0->rt6_next);

		/* no entries matched; do round-robin */
		if (!next || next->rt6i_metric != rt0->rt6i_metric)
			next = leaf;

		if (next != rt0) {
			spin_lock_bh(&leaf->rt6i_table->tb6_lock);
			/* make sure next is not being deleted from the tree */
			if (next->rt6i_node)
				rcu_assign_pointer(fn->rr_ptr, next);
			spin_unlock_bh(&leaf->rt6i_table->tb6_lock);
		}
	}

	return match ? match : net->ipv6.ip6_null_entry;
}

static bool rt6_is_gw_or_nonexthop(const struct rt6_info *rt)
{
	return (rt->rt6i_flags & (RTF_NONEXTHOP | RTF_GATEWAY));
}

#ifdef CONFIG_IPV6_ROUTE_INFO
int rt6_route_rcv(struct net_device *dev, u8 *opt, int len,
		  const struct in6_addr *gwaddr)
{
	struct net *net = dev_net(dev);
	struct route_info *rinfo = (struct route_info *) opt;
	struct in6_addr prefix_buf, *prefix;
	unsigned int pref;
	unsigned long lifetime;
	struct rt6_info *rt;

	if (len < sizeof(struct route_info)) {
		return -EINVAL;
	}

	/* Sanity check for prefix_len and length */
	if (rinfo->length > 3) {
		return -EINVAL;
	} else if (rinfo->prefix_len > 128) {
		return -EINVAL;
	} else if (rinfo->prefix_len > 64) {
		if (rinfo->length < 2) {
			return -EINVAL;
		}
	} else if (rinfo->prefix_len > 0) {
		if (rinfo->length < 1) {
			return -EINVAL;
		}
	}

	pref = rinfo->route_pref;
	if (pref == ICMPV6_ROUTER_PREF_INVALID)
		return -EINVAL;

	lifetime = addrconf_timeout_fixup(ntohl(rinfo->lifetime), HZ);

	if (rinfo->length == 3)
		prefix = (struct in6_addr *)rinfo->prefix;
	else {
		/* this function is safe */
		ipv6_addr_prefix(&prefix_buf,
				 (struct in6_addr *)rinfo->prefix,
				 rinfo->prefix_len);
		prefix = &prefix_buf;
	}

	if (rinfo->prefix_len == 0)
		rt = rt6_get_dflt_router(gwaddr, dev);
	else
		rt = rt6_get_route_info(net, prefix, rinfo->prefix_len,
					gwaddr, dev);

	if (rt && !lifetime) {
		ip6_del_rt(rt);
		rt = NULL;
	}

	if (!rt && lifetime)
		rt = rt6_add_route_info(net, prefix, rinfo->prefix_len, gwaddr,
					dev, pref);
	else if (rt)
		rt->rt6i_flags = RTF_ROUTEINFO |
				 (rt->rt6i_flags & ~RTF_PREF_MASK) | RTF_PREF(pref);

	if (rt) {
		if (!addrconf_finite_timeout(lifetime))
			rt6_clean_expires(rt);
		else
			rt6_set_expires(rt, jiffies + HZ * lifetime);

		ip6_rt_put(rt);
	}
	return 0;
}
#endif

static struct fib6_node* fib6_backtrack(struct fib6_node *fn,
					struct in6_addr *saddr)
{
	struct fib6_node *pn, *sn;
	while (1) {
		if (fn->fn_flags & RTN_TL_ROOT)
			return NULL;
		pn = rcu_dereference(fn->parent);
		sn = FIB6_SUBTREE(pn);
		if (sn && sn != fn)
			fn = fib6_lookup(sn, NULL, saddr);
		else
			fn = pn;
		if (fn->fn_flags & RTN_RTINFO)
			return fn;
	}
}

static bool ip6_hold_safe(struct net *net, struct rt6_info **prt,
			  bool null_fallback)
{
	struct rt6_info *rt = *prt;

	if (dst_hold_safe(&rt->dst))
		return true;
	if (null_fallback) {
		rt = net->ipv6.ip6_null_entry;
		dst_hold(&rt->dst);
	} else {
		rt = NULL;
	}
	*prt = rt;
	return false;
}

static struct rt6_info *ip6_pol_route_lookup(struct net *net,
					     struct fib6_table *table,
					     struct flowi6 *fl6, int flags)
{
	struct rt6_info *rt, *rt_cache;
	struct fib6_node *fn;

	if (fl6->flowi6_flags & FLOWI_FLAG_SKIP_NH_OIF)
		flags &= ~RT6_LOOKUP_F_IFACE;

	rcu_read_lock();
	fn = fib6_lookup(&table->tb6_root, &fl6->daddr, &fl6->saddr);
restart:
	rt = rcu_dereference(fn->leaf);
	if (!rt) {
		rt = net->ipv6.ip6_null_entry;
	} else {
		rt = rt6_device_match(net, rt, &fl6->saddr,
				      fl6->flowi6_oif, flags);
		if (rt->rt6i_nsiblings && fl6->flowi6_oif == 0)
			rt = rt6_multipath_select(rt, fl6,
						  fl6->flowi6_oif, flags);
	}
	if (rt == net->ipv6.ip6_null_entry) {
		fn = fib6_backtrack(fn, &fl6->saddr);
		if (fn)
			goto restart;
	}
	/* Search through exception table */
	rt_cache = rt6_find_cached_rt(rt, &fl6->daddr, &fl6->saddr);
	if (rt_cache)
		rt = rt_cache;

	if (ip6_hold_safe(net, &rt, true))
		dst_use_noref(&rt->dst, jiffies);

	rcu_read_unlock();

	trace_fib6_table_lookup(net, rt, table, fl6);

	return rt;

}

struct dst_entry *ip6_route_lookup(struct net *net, struct flowi6 *fl6,
				    int flags)
{
	return fib6_rule_lookup(net, fl6, flags, ip6_pol_route_lookup);
}
EXPORT_SYMBOL_GPL(ip6_route_lookup);

struct rt6_info *rt6_lookup(struct net *net, const struct in6_addr *daddr,
			    const struct in6_addr *saddr, int oif, int strict)
{
	struct flowi6 fl6 = {
		.flowi6_oif = oif,
		.daddr = *daddr,
	};
	struct dst_entry *dst;
	int flags = strict ? RT6_LOOKUP_F_IFACE : 0;

	if (saddr) {
		memcpy(&fl6.saddr, saddr, sizeof(*saddr));
		flags |= RT6_LOOKUP_F_HAS_SADDR;
	}

	dst = fib6_rule_lookup(net, &fl6, flags, ip6_pol_route_lookup);
	if (dst->error == 0)
		return (struct rt6_info *) dst;

	dst_release(dst);

	return NULL;
}
EXPORT_SYMBOL(rt6_lookup);

/* ip6_ins_rt is called with FREE table->tb6_lock.
 * It takes new route entry, the addition fails by any reason the
 * route is released.
 * Caller must hold dst before calling it.
 */

static int __ip6_ins_rt(struct rt6_info *rt, struct nl_info *info,
			struct mx6_config *mxc,
			struct netlink_ext_ack *extack)
{
	int err;
	struct fib6_table *table;

	table = rt->rt6i_table;
	spin_lock_bh(&table->tb6_lock);
	err = fib6_add(&table->tb6_root, rt, info, mxc, extack);
	spin_unlock_bh(&table->tb6_lock);

	return err;
}

int ip6_ins_rt(struct rt6_info *rt)
{
	struct nl_info info = {	.nl_net = dev_net(rt->dst.dev), };
	struct mx6_config mxc = { .mx = NULL, };

	/* Hold dst to account for the reference from the fib6 tree */
	dst_hold(&rt->dst);
	return __ip6_ins_rt(rt, &info, &mxc, NULL);
}

/* called with rcu_lock held */
static struct net_device *ip6_rt_get_dev_rcu(struct rt6_info *rt)
{
	struct net_device *dev = rt->dst.dev;

	if (rt->rt6i_flags & (RTF_LOCAL | RTF_ANYCAST)) {
		/* for copies of local routes, dst->dev needs to be the
		 * device if it is a master device, the master device if
		 * device is enslaved, and the loopback as the default
		 */
		if (netif_is_l3_slave(dev) &&
		    !rt6_need_strict(&rt->rt6i_dst.addr))
			dev = l3mdev_master_dev_rcu(dev);
		else if (!netif_is_l3_master(dev))
			dev = dev_net(dev)->loopback_dev;
		/* last case is netif_is_l3_master(dev) is true in which
		 * case we want dev returned to be dev
		 */
	}

	return dev;
}

static struct rt6_info *ip6_rt_cache_alloc(struct rt6_info *ort,
					   const struct in6_addr *daddr,
					   const struct in6_addr *saddr)
{
	struct net_device *dev;
	struct rt6_info *rt;

	/*
	 *	Clone the route.
	 */

	if (ort->rt6i_flags & (RTF_CACHE | RTF_PCPU))
		ort = ort->from;

	rcu_read_lock();
	dev = ip6_rt_get_dev_rcu(ort);
	rt = __ip6_dst_alloc(dev_net(dev), dev, 0);
	rcu_read_unlock();
	if (!rt)
		return NULL;

	ip6_rt_copy_init(rt, ort);
	rt->rt6i_flags |= RTF_CACHE;
	rt->rt6i_metric = 0;
	rt->dst.flags |= DST_HOST;
	rt->rt6i_dst.addr = *daddr;
	rt->rt6i_dst.plen = 128;

	if (!rt6_is_gw_or_nonexthop(ort)) {
		if (ort->rt6i_dst.plen != 128 &&
		    ipv6_addr_equal(&ort->rt6i_dst.addr, daddr))
			rt->rt6i_flags |= RTF_ANYCAST;
#ifdef CONFIG_IPV6_SUBTREES
		if (rt->rt6i_src.plen && saddr) {
			rt->rt6i_src.addr = *saddr;
			rt->rt6i_src.plen = 128;
		}
#endif
	}

	return rt;
}

static struct rt6_info *ip6_rt_pcpu_alloc(struct rt6_info *rt)
{
	struct net_device *dev;
	struct rt6_info *pcpu_rt;

	rcu_read_lock();
	dev = ip6_rt_get_dev_rcu(rt);
	pcpu_rt = __ip6_dst_alloc(dev_net(dev), dev, rt->dst.flags);
	rcu_read_unlock();
	if (!pcpu_rt)
		return NULL;
	ip6_rt_copy_init(pcpu_rt, rt);
	pcpu_rt->rt6i_protocol = rt->rt6i_protocol;
	pcpu_rt->rt6i_flags |= RTF_PCPU;
	return pcpu_rt;
}

/* It should be called with rcu_read_lock() acquired */
static struct rt6_info *rt6_get_pcpu_route(struct rt6_info *rt)
{
	struct rt6_info *pcpu_rt, **p;

	p = this_cpu_ptr(rt->rt6i_pcpu);
	pcpu_rt = *p;

	if (pcpu_rt && ip6_hold_safe(NULL, &pcpu_rt, false))
		rt6_dst_from_metrics_check(pcpu_rt);

	return pcpu_rt;
}

static struct rt6_info *rt6_make_pcpu_route(struct rt6_info *rt)
{
	struct rt6_info *pcpu_rt, *prev, **p;

	pcpu_rt = ip6_rt_pcpu_alloc(rt);
	if (!pcpu_rt) {
		struct net *net = dev_net(rt->dst.dev);

		dst_hold(&net->ipv6.ip6_null_entry->dst);
		return net->ipv6.ip6_null_entry;
	}

	dst_hold(&pcpu_rt->dst);
	p = this_cpu_ptr(rt->rt6i_pcpu);
	prev = cmpxchg(p, NULL, pcpu_rt);
	BUG_ON(prev);

	rt6_dst_from_metrics_check(pcpu_rt);
	return pcpu_rt;
}

/* exception hash table implementation
 */
static DEFINE_SPINLOCK(rt6_exception_lock);

/* Remove rt6_ex from hash table and free the memory
 * Caller must hold rt6_exception_lock
 */
static void rt6_remove_exception(struct rt6_exception_bucket *bucket,
				 struct rt6_exception *rt6_ex)
{
	struct net *net;

	if (!bucket || !rt6_ex)
		return;

	net = dev_net(rt6_ex->rt6i->dst.dev);
	rt6_ex->rt6i->rt6i_node = NULL;
	hlist_del_rcu(&rt6_ex->hlist);
	rt6_release(rt6_ex->rt6i);
	kfree_rcu(rt6_ex, rcu);
	WARN_ON_ONCE(!bucket->depth);
	bucket->depth--;
	net->ipv6.rt6_stats->fib_rt_cache--;
}

/* Remove oldest rt6_ex in bucket and free the memory
 * Caller must hold rt6_exception_lock
 */
static void rt6_exception_remove_oldest(struct rt6_exception_bucket *bucket)
{
	struct rt6_exception *rt6_ex, *oldest = NULL;

	if (!bucket)
		return;

	hlist_for_each_entry(rt6_ex, &bucket->chain, hlist) {
		if (!oldest || time_before(rt6_ex->stamp, oldest->stamp))
			oldest = rt6_ex;
	}
	rt6_remove_exception(bucket, oldest);
}

static u32 rt6_exception_hash(const struct in6_addr *dst,
			      const struct in6_addr *src)
{
	static u32 seed __read_mostly;
	u32 val;

	net_get_random_once(&seed, sizeof(seed));
	val = jhash(dst, sizeof(*dst), seed);

#ifdef CONFIG_IPV6_SUBTREES
	if (src)
		val = jhash(src, sizeof(*src), val);
#endif
	return hash_32(val, FIB6_EXCEPTION_BUCKET_SIZE_SHIFT);
}

/* Helper function to find the cached rt in the hash table
 * and update bucket pointer to point to the bucket for this
 * (daddr, saddr) pair
 * Caller must hold rt6_exception_lock
 */
static struct rt6_exception *
__rt6_find_exception_spinlock(struct rt6_exception_bucket **bucket,
			      const struct in6_addr *daddr,
			      const struct in6_addr *saddr)
{
	struct rt6_exception *rt6_ex;
	u32 hval;

	if (!(*bucket) || !daddr)
		return NULL;

	hval = rt6_exception_hash(daddr, saddr);
	*bucket += hval;

	hlist_for_each_entry(rt6_ex, &(*bucket)->chain, hlist) {
		struct rt6_info *rt6 = rt6_ex->rt6i;
		bool matched = ipv6_addr_equal(daddr, &rt6->rt6i_dst.addr);

#ifdef CONFIG_IPV6_SUBTREES
		if (matched && saddr)
			matched = ipv6_addr_equal(saddr, &rt6->rt6i_src.addr);
#endif
		if (matched)
			return rt6_ex;
	}
	return NULL;
}

/* Helper function to find the cached rt in the hash table
 * and update bucket pointer to point to the bucket for this
 * (daddr, saddr) pair
 * Caller must hold rcu_read_lock()
 */
static struct rt6_exception *
__rt6_find_exception_rcu(struct rt6_exception_bucket **bucket,
			 const struct in6_addr *daddr,
			 const struct in6_addr *saddr)
{
	struct rt6_exception *rt6_ex;
	u32 hval;

	WARN_ON_ONCE(!rcu_read_lock_held());

	if (!(*bucket) || !daddr)
		return NULL;

	hval = rt6_exception_hash(daddr, saddr);
	*bucket += hval;

	hlist_for_each_entry_rcu(rt6_ex, &(*bucket)->chain, hlist) {
		struct rt6_info *rt6 = rt6_ex->rt6i;
		bool matched = ipv6_addr_equal(daddr, &rt6->rt6i_dst.addr);

#ifdef CONFIG_IPV6_SUBTREES
		if (matched && saddr)
			matched = ipv6_addr_equal(saddr, &rt6->rt6i_src.addr);
#endif
		if (matched)
			return rt6_ex;
	}
	return NULL;
}

static int rt6_insert_exception(struct rt6_info *nrt,
				struct rt6_info *ort)
{
	struct net *net = dev_net(ort->dst.dev);
	struct rt6_exception_bucket *bucket;
	struct in6_addr *src_key = NULL;
	struct rt6_exception *rt6_ex;
	int err = 0;

	/* ort can't be a cache or pcpu route */
	if (ort->rt6i_flags & (RTF_CACHE | RTF_PCPU))
		ort = ort->from;
	WARN_ON_ONCE(ort->rt6i_flags & (RTF_CACHE | RTF_PCPU));

	spin_lock_bh(&rt6_exception_lock);

	if (ort->exception_bucket_flushed) {
		err = -EINVAL;
		goto out;
	}

	bucket = rcu_dereference_protected(ort->rt6i_exception_bucket,
					lockdep_is_held(&rt6_exception_lock));
	if (!bucket) {
		bucket = kcalloc(FIB6_EXCEPTION_BUCKET_SIZE, sizeof(*bucket),
				 GFP_ATOMIC);
		if (!bucket) {
			err = -ENOMEM;
			goto out;
		}
		rcu_assign_pointer(ort->rt6i_exception_bucket, bucket);
	}

#ifdef CONFIG_IPV6_SUBTREES
	/* rt6i_src.plen != 0 indicates ort is in subtree
	 * and exception table is indexed by a hash of
	 * both rt6i_dst and rt6i_src.
	 * Otherwise, the exception table is indexed by
	 * a hash of only rt6i_dst.
	 */
	if (ort->rt6i_src.plen)
		src_key = &nrt->rt6i_src.addr;
#endif

	/* Update rt6i_prefsrc as it could be changed
	 * in rt6_remove_prefsrc()
	 */
	nrt->rt6i_prefsrc = ort->rt6i_prefsrc;
	/* rt6_mtu_change() might lower mtu on ort.
	 * Only insert this exception route if its mtu
	 * is less than ort's mtu value.
	 */
	if (nrt->rt6i_pmtu >= dst_mtu(&ort->dst)) {
		err = -EINVAL;
		goto out;
	}

	rt6_ex = __rt6_find_exception_spinlock(&bucket, &nrt->rt6i_dst.addr,
					       src_key);
	if (rt6_ex)
		rt6_remove_exception(bucket, rt6_ex);

	rt6_ex = kzalloc(sizeof(*rt6_ex), GFP_ATOMIC);
	if (!rt6_ex) {
		err = -ENOMEM;
		goto out;
	}
	rt6_ex->rt6i = nrt;
	rt6_ex->stamp = jiffies;
	atomic_inc(&nrt->rt6i_ref);
	nrt->rt6i_node = ort->rt6i_node;
	hlist_add_head_rcu(&rt6_ex->hlist, &bucket->chain);
	bucket->depth++;
	net->ipv6.rt6_stats->fib_rt_cache++;

	if (bucket->depth > FIB6_MAX_DEPTH)
		rt6_exception_remove_oldest(bucket);

out:
	spin_unlock_bh(&rt6_exception_lock);

	/* Update fn->fn_sernum to invalidate all cached dst */
	if (!err) {
		spin_lock_bh(&ort->rt6i_table->tb6_lock);
		fib6_update_sernum(ort);
		spin_unlock_bh(&ort->rt6i_table->tb6_lock);
		fib6_force_start_gc(net);
	}

	return err;
}

void rt6_flush_exceptions(struct rt6_info *rt)
{
	struct rt6_exception_bucket *bucket;
	struct rt6_exception *rt6_ex;
	struct hlist_node *tmp;
	int i;

	spin_lock_bh(&rt6_exception_lock);
	/* Prevent rt6_insert_exception() to recreate the bucket list */
	rt->exception_bucket_flushed = 1;

	bucket = rcu_dereference_protected(rt->rt6i_exception_bucket,
				    lockdep_is_held(&rt6_exception_lock));
	if (!bucket)
		goto out;

	for (i = 0; i < FIB6_EXCEPTION_BUCKET_SIZE; i++) {
		hlist_for_each_entry_safe(rt6_ex, tmp, &bucket->chain, hlist)
			rt6_remove_exception(bucket, rt6_ex);
		WARN_ON_ONCE(bucket->depth);
		bucket++;
	}

out:
	spin_unlock_bh(&rt6_exception_lock);
}

/* Find cached rt in the hash table inside passed in rt
 * Caller has to hold rcu_read_lock()
 */
static struct rt6_info *rt6_find_cached_rt(struct rt6_info *rt,
					   struct in6_addr *daddr,
					   struct in6_addr *saddr)
{
	struct rt6_exception_bucket *bucket;
	struct in6_addr *src_key = NULL;
	struct rt6_exception *rt6_ex;
	struct rt6_info *res = NULL;

	bucket = rcu_dereference(rt->rt6i_exception_bucket);

#ifdef CONFIG_IPV6_SUBTREES
	/* rt6i_src.plen != 0 indicates rt is in subtree
	 * and exception table is indexed by a hash of
	 * both rt6i_dst and rt6i_src.
	 * Otherwise, the exception table is indexed by
	 * a hash of only rt6i_dst.
	 */
	if (rt->rt6i_src.plen)
		src_key = saddr;
#endif
	rt6_ex = __rt6_find_exception_rcu(&bucket, daddr, src_key);

	if (rt6_ex && !rt6_check_expired(rt6_ex->rt6i))
		res = rt6_ex->rt6i;

	return res;
}

/* Remove the passed in cached rt from the hash table that contains it */
int rt6_remove_exception_rt(struct rt6_info *rt)
{
	struct rt6_exception_bucket *bucket;
	struct rt6_info *from = rt->from;
	struct in6_addr *src_key = NULL;
	struct rt6_exception *rt6_ex;
	int err;

	if (!from ||
	    !(rt->rt6i_flags & RTF_CACHE))
		return -EINVAL;

	if (!rcu_access_pointer(from->rt6i_exception_bucket))
		return -ENOENT;

	spin_lock_bh(&rt6_exception_lock);
	bucket = rcu_dereference_protected(from->rt6i_exception_bucket,
				    lockdep_is_held(&rt6_exception_lock));
#ifdef CONFIG_IPV6_SUBTREES
	/* rt6i_src.plen != 0 indicates 'from' is in subtree
	 * and exception table is indexed by a hash of
	 * both rt6i_dst and rt6i_src.
	 * Otherwise, the exception table is indexed by
	 * a hash of only rt6i_dst.
	 */
	if (from->rt6i_src.plen)
		src_key = &rt->rt6i_src.addr;
#endif
	rt6_ex = __rt6_find_exception_spinlock(&bucket,
					       &rt->rt6i_dst.addr,
					       src_key);
	if (rt6_ex) {
		rt6_remove_exception(bucket, rt6_ex);
		err = 0;
	} else {
		err = -ENOENT;
	}

	spin_unlock_bh(&rt6_exception_lock);
	return err;
}

/* Find rt6_ex which contains the passed in rt cache and
 * refresh its stamp
 */
static void rt6_update_exception_stamp_rt(struct rt6_info *rt)
{
	struct rt6_exception_bucket *bucket;
	struct rt6_info *from = rt->from;
	struct in6_addr *src_key = NULL;
	struct rt6_exception *rt6_ex;

	if (!from ||
	    !(rt->rt6i_flags & RTF_CACHE))
		return;

	rcu_read_lock();
	bucket = rcu_dereference(from->rt6i_exception_bucket);

#ifdef CONFIG_IPV6_SUBTREES
	/* rt6i_src.plen != 0 indicates 'from' is in subtree
	 * and exception table is indexed by a hash of
	 * both rt6i_dst and rt6i_src.
	 * Otherwise, the exception table is indexed by
	 * a hash of only rt6i_dst.
	 */
	if (from->rt6i_src.plen)
		src_key = &rt->rt6i_src.addr;
#endif
	rt6_ex = __rt6_find_exception_rcu(&bucket,
					  &rt->rt6i_dst.addr,
					  src_key);
	if (rt6_ex)
		rt6_ex->stamp = jiffies;

	rcu_read_unlock();
}

static void rt6_exceptions_remove_prefsrc(struct rt6_info *rt)
{
	struct rt6_exception_bucket *bucket;
	struct rt6_exception *rt6_ex;
	int i;

	bucket = rcu_dereference_protected(rt->rt6i_exception_bucket,
					lockdep_is_held(&rt6_exception_lock));

	if (bucket) {
		for (i = 0; i < FIB6_EXCEPTION_BUCKET_SIZE; i++) {
			hlist_for_each_entry(rt6_ex, &bucket->chain, hlist) {
				rt6_ex->rt6i->rt6i_prefsrc.plen = 0;
			}
			bucket++;
		}
	}
}

static bool rt6_mtu_change_route_allowed(struct inet6_dev *idev,
					 struct rt6_info *rt, int mtu)
{
	/* If the new MTU is lower than the route PMTU, this new MTU will be the
	 * lowest MTU in the path: always allow updating the route PMTU to
	 * reflect PMTU decreases.
	 *
	 * If the new MTU is higher, and the route PMTU is equal to the local
	 * MTU, this means the old MTU is the lowest in the path, so allow
	 * updating it: if other nodes now have lower MTUs, PMTU discovery will
	 * handle this.
	 */

	if (dst_mtu(&rt->dst) >= mtu)
		return true;

	if (dst_mtu(&rt->dst) == idev->cnf.mtu6)
		return true;

	return false;
}

static void rt6_exceptions_update_pmtu(struct inet6_dev *idev,
				       struct rt6_info *rt, int mtu)
{
	struct rt6_exception_bucket *bucket;
	struct rt6_exception *rt6_ex;
	int i;

	bucket = rcu_dereference_protected(rt->rt6i_exception_bucket,
					lockdep_is_held(&rt6_exception_lock));

	if (!bucket)
		return;

	for (i = 0; i < FIB6_EXCEPTION_BUCKET_SIZE; i++) {
		hlist_for_each_entry(rt6_ex, &bucket->chain, hlist) {
			struct rt6_info *entry = rt6_ex->rt6i;

			/* For RTF_CACHE with rt6i_pmtu == 0 (i.e. a redirected
			 * route), the metrics of its rt->dst.from have already
			 * been updated.
			 */
			if (entry->rt6i_pmtu &&
			    rt6_mtu_change_route_allowed(idev, entry, mtu))
				entry->rt6i_pmtu = mtu;
		}
		bucket++;
	}
}

#define RTF_CACHE_GATEWAY	(RTF_GATEWAY | RTF_CACHE)

static void rt6_exceptions_clean_tohost(struct rt6_info *rt,
					struct in6_addr *gateway)
{
	struct rt6_exception_bucket *bucket;
	struct rt6_exception *rt6_ex;
	struct hlist_node *tmp;
	int i;

	if (!rcu_access_pointer(rt->rt6i_exception_bucket))
		return;

	spin_lock_bh(&rt6_exception_lock);
	bucket = rcu_dereference_protected(rt->rt6i_exception_bucket,
				     lockdep_is_held(&rt6_exception_lock));

	if (bucket) {
		for (i = 0; i < FIB6_EXCEPTION_BUCKET_SIZE; i++) {
			hlist_for_each_entry_safe(rt6_ex, tmp,
						  &bucket->chain, hlist) {
				struct rt6_info *entry = rt6_ex->rt6i;

				if ((entry->rt6i_flags & RTF_CACHE_GATEWAY) ==
				    RTF_CACHE_GATEWAY &&
				    ipv6_addr_equal(gateway,
						    &entry->rt6i_gateway)) {
					rt6_remove_exception(bucket, rt6_ex);
				}
			}
			bucket++;
		}
	}

	spin_unlock_bh(&rt6_exception_lock);
}

static void rt6_age_examine_exception(struct rt6_exception_bucket *bucket,
				      struct rt6_exception *rt6_ex,
				      struct fib6_gc_args *gc_args,
				      unsigned long now)
{
	struct rt6_info *rt = rt6_ex->rt6i;

	/* we are pruning and obsoleting aged-out and non gateway exceptions
	 * even if others have still references to them, so that on next
	 * dst_check() such references can be dropped.
	 * EXPIRES exceptions - e.g. pmtu-generated ones are pruned when
	 * expired, independently from their aging, as per RFC 8201 section 4
	 */
	if (!(rt->rt6i_flags & RTF_EXPIRES)) {
		if (time_after_eq(now, rt->dst.lastuse + gc_args->timeout)) {
			RT6_TRACE("aging clone %p\n", rt);
			rt6_remove_exception(bucket, rt6_ex);
			return;
		}
	} else if (time_after(jiffies, rt->dst.expires)) {
		RT6_TRACE("purging expired route %p\n", rt);
		rt6_remove_exception(bucket, rt6_ex);
		return;
	}

	if (rt->rt6i_flags & RTF_GATEWAY) {
		struct neighbour *neigh;
		__u8 neigh_flags = 0;

		neigh = __ipv6_neigh_lookup_noref(rt->dst.dev, &rt->rt6i_gateway);
		if (neigh)
			neigh_flags = neigh->flags;

		if (!(neigh_flags & NTF_ROUTER)) {
			RT6_TRACE("purging route %p via non-router but gateway\n",
				  rt);
			rt6_remove_exception(bucket, rt6_ex);
			return;
		}
	}

	gc_args->more++;
}

void rt6_age_exceptions(struct rt6_info *rt,
			struct fib6_gc_args *gc_args,
			unsigned long now)
{
	struct rt6_exception_bucket *bucket;
	struct rt6_exception *rt6_ex;
	struct hlist_node *tmp;
	int i;

	if (!rcu_access_pointer(rt->rt6i_exception_bucket))
		return;

	rcu_read_lock_bh();
	spin_lock(&rt6_exception_lock);
	bucket = rcu_dereference_protected(rt->rt6i_exception_bucket,
				    lockdep_is_held(&rt6_exception_lock));

	if (bucket) {
		for (i = 0; i < FIB6_EXCEPTION_BUCKET_SIZE; i++) {
			hlist_for_each_entry_safe(rt6_ex, tmp,
						  &bucket->chain, hlist) {
				rt6_age_examine_exception(bucket, rt6_ex,
							  gc_args, now);
			}
			bucket++;
		}
	}
	spin_unlock(&rt6_exception_lock);
	rcu_read_unlock_bh();
}

struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
			       int oif, struct flowi6 *fl6, int flags)
{
	struct fib6_node *fn, *saved_fn;
	struct rt6_info *rt, *rt_cache;
	int strict = 0;

	strict |= flags & RT6_LOOKUP_F_IFACE;
	strict |= flags & RT6_LOOKUP_F_IGNORE_LINKSTATE;
	if (net->ipv6.devconf_all->forwarding == 0)
		strict |= RT6_LOOKUP_F_REACHABLE;

	rcu_read_lock();

	fn = fib6_lookup(&table->tb6_root, &fl6->daddr, &fl6->saddr);
	saved_fn = fn;

	if (fl6->flowi6_flags & FLOWI_FLAG_SKIP_NH_OIF)
		oif = 0;

redo_rt6_select:
	rt = rt6_select(net, fn, oif, strict);
	if (rt->rt6i_nsiblings)
		rt = rt6_multipath_select(rt, fl6, oif, strict);
	if (rt == net->ipv6.ip6_null_entry) {
		fn = fib6_backtrack(fn, &fl6->saddr);
		if (fn)
			goto redo_rt6_select;
		else if (strict & RT6_LOOKUP_F_REACHABLE) {
			/* also consider unreachable route */
			strict &= ~RT6_LOOKUP_F_REACHABLE;
			fn = saved_fn;
			goto redo_rt6_select;
		}
	}

	/*Search through exception table */
	rt_cache = rt6_find_cached_rt(rt, &fl6->daddr, &fl6->saddr);
	if (rt_cache)
		rt = rt_cache;

	if (rt == net->ipv6.ip6_null_entry) {
		rcu_read_unlock();
		dst_hold(&rt->dst);
		trace_fib6_table_lookup(net, rt, table, fl6);
		return rt;
	} else if (rt->rt6i_flags & RTF_CACHE) {
		if (ip6_hold_safe(net, &rt, true)) {
			dst_use_noref(&rt->dst, jiffies);
			rt6_dst_from_metrics_check(rt);
		}
		rcu_read_unlock();
		trace_fib6_table_lookup(net, rt, table, fl6);
		return rt;
	} else if (unlikely((fl6->flowi6_flags & FLOWI_FLAG_KNOWN_NH) &&
			    !(rt->rt6i_flags & RTF_GATEWAY))) {
		/* Create a RTF_CACHE clone which will not be
		 * owned by the fib6 tree.  It is for the special case where
		 * the daddr in the skb during the neighbor look-up is different
		 * from the fl6->daddr used to look-up route here.
		 */

		struct rt6_info *uncached_rt;

		if (ip6_hold_safe(net, &rt, true)) {
			dst_use_noref(&rt->dst, jiffies);
		} else {
			rcu_read_unlock();
			uncached_rt = rt;
			goto uncached_rt_out;
		}
		rcu_read_unlock();

		uncached_rt = ip6_rt_cache_alloc(rt, &fl6->daddr, NULL);
		dst_release(&rt->dst);

		if (uncached_rt) {
			/* Uncached_rt's refcnt is taken during ip6_rt_cache_alloc()
			 * No need for another dst_hold()
			 */
			rt6_uncached_list_add(uncached_rt);
			atomic_inc(&net->ipv6.rt6_stats->fib_rt_uncache);
		} else {
			uncached_rt = net->ipv6.ip6_null_entry;
			dst_hold(&uncached_rt->dst);
		}

uncached_rt_out:
		trace_fib6_table_lookup(net, uncached_rt, table, fl6);
		return uncached_rt;

	} else {
		/* Get a percpu copy */

		struct rt6_info *pcpu_rt;

		dst_use_noref(&rt->dst, jiffies);
		local_bh_disable();
		pcpu_rt = rt6_get_pcpu_route(rt);

		if (!pcpu_rt) {
			/* atomic_inc_not_zero() is needed when using rcu */
			if (atomic_inc_not_zero(&rt->rt6i_ref)) {
				/* No dst_hold() on rt is needed because grabbing
				 * rt->rt6i_ref makes sure rt can't be released.
				 */
				pcpu_rt = rt6_make_pcpu_route(rt);
				rt6_release(rt);
			} else {
				/* rt is already removed from tree */
				pcpu_rt = net->ipv6.ip6_null_entry;
				dst_hold(&pcpu_rt->dst);
			}
		}
		local_bh_enable();
		rcu_read_unlock();
		trace_fib6_table_lookup(net, pcpu_rt, table, fl6);
		return pcpu_rt;
	}
}
EXPORT_SYMBOL_GPL(ip6_pol_route);

static struct rt6_info *ip6_pol_route_input(struct net *net, struct fib6_table *table,
					    struct flowi6 *fl6, int flags)
{
	return ip6_pol_route(net, table, fl6->flowi6_iif, fl6, flags);
}

struct dst_entry *ip6_route_input_lookup(struct net *net,
					 struct net_device *dev,
					 struct flowi6 *fl6, int flags)
{
	if (rt6_need_strict(&fl6->daddr) && dev->type != ARPHRD_PIMREG)
		flags |= RT6_LOOKUP_F_IFACE;

	return fib6_rule_lookup(net, fl6, flags, ip6_pol_route_input);
}
EXPORT_SYMBOL_GPL(ip6_route_input_lookup);

static void ip6_multipath_l3_keys(const struct sk_buff *skb,
				  struct flow_keys *keys)
{
	const struct ipv6hdr *outer_iph = ipv6_hdr(skb);
	const struct ipv6hdr *key_iph = outer_iph;
	const struct ipv6hdr *inner_iph;
	const struct icmp6hdr *icmph;
	struct ipv6hdr _inner_iph;

	if (likely(outer_iph->nexthdr != IPPROTO_ICMPV6))
		goto out;

	icmph = icmp6_hdr(skb);
	if (icmph->icmp6_type != ICMPV6_DEST_UNREACH &&
	    icmph->icmp6_type != ICMPV6_PKT_TOOBIG &&
	    icmph->icmp6_type != ICMPV6_TIME_EXCEED &&
	    icmph->icmp6_type != ICMPV6_PARAMPROB)
		goto out;

	inner_iph = skb_header_pointer(skb,
				       skb_transport_offset(skb) + sizeof(*icmph),
				       sizeof(_inner_iph), &_inner_iph);
	if (!inner_iph)
		goto out;

	key_iph = inner_iph;
out:
	memset(keys, 0, sizeof(*keys));
	keys->control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
	keys->addrs.v6addrs.src = key_iph->saddr;
	keys->addrs.v6addrs.dst = key_iph->daddr;
	keys->tags.flow_label = ip6_flowinfo(key_iph);
	keys->basic.ip_proto = key_iph->nexthdr;
}

/* if skb is set it will be used and fl6 can be NULL */
u32 rt6_multipath_hash(const struct flowi6 *fl6, const struct sk_buff *skb)
{
	struct flow_keys hash_keys;

	if (skb) {
		ip6_multipath_l3_keys(skb, &hash_keys);
		return flow_hash_from_keys(&hash_keys) >> 1;
	}

	return get_hash_from_flowi6(fl6) >> 1;
}

void ip6_route_input(struct sk_buff *skb)
{
	const struct ipv6hdr *iph = ipv6_hdr(skb);
	struct net *net = dev_net(skb->dev);
	int flags = RT6_LOOKUP_F_HAS_SADDR;
	struct ip_tunnel_info *tun_info;
	struct flowi6 fl6 = {
		.flowi6_iif = skb->dev->ifindex,
		.daddr = iph->daddr,
		.saddr = iph->saddr,
		.flowlabel = ip6_flowinfo(iph),
		.flowi6_mark = skb->mark,
		.flowi6_proto = iph->nexthdr,
	};

	tun_info = skb_tunnel_info(skb);
	if (tun_info && !(tun_info->mode & IP_TUNNEL_INFO_TX))
		fl6.flowi6_tun_key.tun_id = tun_info->key.tun_id;
	if (unlikely(fl6.flowi6_proto == IPPROTO_ICMPV6))
		fl6.mp_hash = rt6_multipath_hash(&fl6, skb);
	skb_dst_drop(skb);
	skb_dst_set(skb, ip6_route_input_lookup(net, skb->dev, &fl6, flags));
}

static struct rt6_info *ip6_pol_route_output(struct net *net, struct fib6_table *table,
					     struct flowi6 *fl6, int flags)
{
	return ip6_pol_route(net, table, fl6->flowi6_oif, fl6, flags);
}

struct dst_entry *ip6_route_output_flags(struct net *net, const struct sock *sk,
					 struct flowi6 *fl6, int flags)
{
	bool any_src;

	if (rt6_need_strict(&fl6->daddr)) {
		struct dst_entry *dst;

		dst = l3mdev_link_scope_lookup(net, fl6);
		if (dst)
			return dst;
	}

	fl6->flowi6_iif = LOOPBACK_IFINDEX;

	any_src = ipv6_addr_any(&fl6->saddr);
	if ((sk && sk->sk_bound_dev_if) || rt6_need_strict(&fl6->daddr) ||
	    (fl6->flowi6_oif && any_src))
		flags |= RT6_LOOKUP_F_IFACE;

	if (!any_src)
		flags |= RT6_LOOKUP_F_HAS_SADDR;
	else if (sk)
		flags |= rt6_srcprefs2flags(inet6_sk(sk)->srcprefs);

	return fib6_rule_lookup(net, fl6, flags, ip6_pol_route_output);
}
EXPORT_SYMBOL_GPL(ip6_route_output_flags);

struct dst_entry *ip6_blackhole_route(struct net *net, struct dst_entry *dst_orig)
{
	struct rt6_info *rt, *ort = (struct rt6_info *) dst_orig;
	struct net_device *loopback_dev = net->loopback_dev;
	struct dst_entry *new = NULL;

	rt = dst_alloc(&ip6_dst_blackhole_ops, loopback_dev, 1,
		       DST_OBSOLETE_DEAD, 0);
	if (rt) {
		rt6_info_init(rt);
		atomic_inc(&net->ipv6.rt6_stats->fib_rt_alloc);

		new = &rt->dst;
		new->__use = 1;
		new->input = dst_discard;
		new->output = dst_discard_out;

		dst_copy_metrics(new, &ort->dst);

		rt->rt6i_idev = in6_dev_get(loopback_dev);
		rt->rt6i_gateway = ort->rt6i_gateway;
		rt->rt6i_flags = ort->rt6i_flags & ~RTF_PCPU;
		rt->rt6i_metric = 0;

		memcpy(&rt->rt6i_dst, &ort->rt6i_dst, sizeof(struct rt6key));
#ifdef CONFIG_IPV6_SUBTREES
		memcpy(&rt->rt6i_src, &ort->rt6i_src, sizeof(struct rt6key));
#endif
	}

	dst_release(dst_orig);
	return new ? new : ERR_PTR(-ENOMEM);
}

/*
 *	Destination cache support functions
 */

static void rt6_dst_from_metrics_check(struct rt6_info *rt)
{
	if (rt->from &&
	    dst_metrics_ptr(&rt->dst) != dst_metrics_ptr(&rt->from->dst))
		dst_init_metrics(&rt->dst, dst_metrics_ptr(&rt->from->dst), true);
}

static struct dst_entry *rt6_check(struct rt6_info *rt, u32 cookie)
{
	u32 rt_cookie = 0;

	if (!rt6_get_cookie_safe(rt, &rt_cookie) || rt_cookie != cookie)
		return NULL;

	if (rt6_check_expired(rt))
		return NULL;

	return &rt->dst;
}

static struct dst_entry *rt6_dst_from_check(struct rt6_info *rt, u32 cookie)
{
	if (!__rt6_check_expired(rt) &&
	    rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK &&
	    rt6_check(rt->from, cookie))
		return &rt->dst;
	else
		return NULL;
}

static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
{
	struct rt6_info *rt;

	rt = (struct rt6_info *) dst;

	/* All IPV6 dsts are created with ->obsolete set to the value
	 * DST_OBSOLETE_FORCE_CHK which forces validation calls down
	 * into this function always.
	 */

	rt6_dst_from_metrics_check(rt);

	if (rt->rt6i_flags & RTF_PCPU ||
	    (unlikely(!list_empty(&rt->rt6i_uncached)) && rt->from))
		return rt6_dst_from_check(rt, cookie);
	else
		return rt6_check(rt, cookie);
}

static struct dst_entry *ip6_negative_advice(struct dst_entry *dst)
{
	struct rt6_info *rt = (struct rt6_info *) dst;

	if (rt) {
		if (rt->rt6i_flags & RTF_CACHE) {
			if (rt6_check_expired(rt)) {
				ip6_del_rt(rt);
				dst = NULL;
			}
		} else {
			dst_release(dst);
			dst = NULL;
		}
	}
	return dst;
}

static void ip6_link_failure(struct sk_buff *skb)
{
	struct rt6_info *rt;

	icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH, 0);

	rt = (struct rt6_info *) skb_dst(skb);
	if (rt) {
		if (rt->rt6i_flags & RTF_CACHE) {
			if (dst_hold_safe(&rt->dst))
				ip6_del_rt(rt);
		} else {
			struct fib6_node *fn;

			rcu_read_lock();
			fn = rcu_dereference(rt->rt6i_node);
			if (fn && (rt->rt6i_flags & RTF_DEFAULT))
				fn->fn_sernum = -1;
			rcu_read_unlock();
		}
	}
}

static void rt6_do_update_pmtu(struct rt6_info *rt, u32 mtu)
{
	struct net *net = dev_net(rt->dst.dev);

	rt->rt6i_flags |= RTF_MODIFIED;
	rt->rt6i_pmtu = mtu;
	rt6_update_expires(rt, net->ipv6.sysctl.ip6_rt_mtu_expires);
}

static bool rt6_cache_allowed_for_pmtu(const struct rt6_info *rt)
{
	return !(rt->rt6i_flags & RTF_CACHE) &&
		(rt->rt6i_flags & RTF_PCPU ||
		 rcu_access_pointer(rt->rt6i_node));
}

static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
				 const struct ipv6hdr *iph, u32 mtu)
{
	const struct in6_addr *daddr, *saddr;
	struct rt6_info *rt6 = (struct rt6_info *)dst;

	if (rt6->rt6i_flags & RTF_LOCAL)
		return;

	if (dst_metric_locked(dst, RTAX_MTU))
		return;

	if (iph) {
		daddr = &iph->daddr;
		saddr = &iph->saddr;
	} else if (sk) {
		daddr = &sk->sk_v6_daddr;
		saddr = &inet6_sk(sk)->saddr;
	} else {
		daddr = NULL;
		saddr = NULL;
	}
	dst_confirm_neigh(dst, daddr);
	mtu = max_t(u32, mtu, IPV6_MIN_MTU);
	if (mtu >= dst_mtu(dst))
		return;

	if (!rt6_cache_allowed_for_pmtu(rt6)) {
		rt6_do_update_pmtu(rt6, mtu);
		/* update rt6_ex->stamp for cache */
		if (rt6->rt6i_flags & RTF_CACHE)
			rt6_update_exception_stamp_rt(rt6);
	} else if (daddr) {
		struct rt6_info *nrt6;

		nrt6 = ip6_rt_cache_alloc(rt6, daddr, saddr);
		if (nrt6) {
			rt6_do_update_pmtu(nrt6, mtu);
			if (rt6_insert_exception(nrt6, rt6))
				dst_release_immediate(&nrt6->dst);
		}
	}
}

static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
			       struct sk_buff *skb, u32 mtu)
{
	__ip6_rt_update_pmtu(dst, sk, skb ? ipv6_hdr(skb) : NULL, mtu);
}

void ip6_update_pmtu(struct sk_buff *skb, struct net *net, __be32 mtu,
		     int oif, u32 mark, kuid_t uid)
{
	const struct ipv6hdr *iph = (struct ipv6hdr *) skb->data;
	struct dst_entry *dst;
	struct flowi6 fl6;

	memset(&fl6, 0, sizeof(fl6));
	fl6.flowi6_oif = oif;
	fl6.flowi6_mark = mark ? mark : IP6_REPLY_MARK(net, skb->mark);
	fl6.daddr = iph->daddr;
	fl6.saddr = iph->saddr;
	fl6.flowlabel = ip6_flowinfo(iph);
	fl6.flowi6_uid = uid;

	dst = ip6_route_output(net, NULL, &fl6);
	if (!dst->error)
		__ip6_rt_update_pmtu(dst, NULL, iph, ntohl(mtu));
	dst_release(dst);
}
EXPORT_SYMBOL_GPL(ip6_update_pmtu);

void ip6_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, __be32 mtu)
{
	struct dst_entry *dst;

	ip6_update_pmtu(skb, sock_net(sk), mtu,
			sk->sk_bound_dev_if, sk->sk_mark, sk->sk_uid);

	dst = __sk_dst_get(sk);
	if (!dst || !dst->obsolete ||
	    dst->ops->check(dst, inet6_sk(sk)->dst_cookie))
		return;

	bh_lock_sock(sk);
	if (!sock_owned_by_user(sk) && !ipv6_addr_v4mapped(&sk->sk_v6_daddr))
		ip6_datagram_dst_update(sk, false);
	bh_unlock_sock(sk);
}
EXPORT_SYMBOL_GPL(ip6_sk_update_pmtu);

/* Handle redirects */
struct ip6rd_flowi {
	struct flowi6 fl6;
	struct in6_addr gateway;
};

static struct rt6_info *__ip6_route_redirect(struct net *net,
					     struct fib6_table *table,
					     struct flowi6 *fl6,
					     int flags)
{
	struct ip6rd_flowi *rdfl = (struct ip6rd_flowi *)fl6;
	struct rt6_info *rt, *rt_cache;
	struct fib6_node *fn;

	/* Get the "current" route for this destination and
	 * check if the redirect has come from appropriate router.
	 *
	 * RFC 4861 specifies that redirects should only be
	 * accepted if they come from the nexthop to the target.
	 * Due to the way the routes are chosen, this notion
	 * is a bit fuzzy and one might need to check all possible
	 * routes.
	 */

	rcu_read_lock();
	fn = fib6_lookup(&table->tb6_root, &fl6->daddr, &fl6->saddr);
restart:
	for_each_fib6_node_rt_rcu(fn) {
		if (rt->rt6i_nh_flags & RTNH_F_DEAD)
			continue;
		if (rt6_check_expired(rt))
			continue;
		if (rt->dst.error)
			break;
		if (!(rt->rt6i_flags & RTF_GATEWAY))
			continue;
		if (fl6->flowi6_oif != rt->dst.dev->ifindex)
			continue;
		/* rt_cache's gateway might be different from its 'parent'
		 * in the case of an ip redirect.
		 * So we keep searching in the exception table if the gateway
		 * is different.
		 */
		if (!ipv6_addr_equal(&rdfl->gateway, &rt->rt6i_gateway)) {
			rt_cache = rt6_find_cached_rt(rt,
						      &fl6->daddr,
						      &fl6->saddr);
			if (rt_cache &&
			    ipv6_addr_equal(&rdfl->gateway,
					    &rt_cache->rt6i_gateway)) {
				rt = rt_cache;
				break;
			}
			continue;
		}
		break;
	}

	if (!rt)
		rt = net->ipv6.ip6_null_entry;
	else if (rt->dst.error) {
		rt = net->ipv6.ip6_null_entry;
		goto out;
	}

	if (rt == net->ipv6.ip6_null_entry) {
		fn = fib6_backtrack(fn, &fl6->saddr);
		if (fn)
			goto restart;
	}

out:
	ip6_hold_safe(net, &rt, true);

	rcu_read_unlock();

	trace_fib6_table_lookup(net, rt, table, fl6);
	return rt;
};

static struct dst_entry *ip6_route_redirect(struct net *net,
					const struct flowi6 *fl6,
					const struct in6_addr *gateway)
{
	int flags = RT6_LOOKUP_F_HAS_SADDR;
	struct ip6rd_flowi rdfl;

	rdfl.fl6 = *fl6;
	rdfl.gateway = *gateway;

	return fib6_rule_lookup(net, &rdfl.fl6,
				flags, __ip6_route_redirect);
}

void ip6_redirect(struct sk_buff *skb, struct net *net, int oif, u32 mark,
		  kuid_t uid)
{
	const struct ipv6hdr *iph = (struct ipv6hdr *) skb->data;
	struct dst_entry *dst;
	struct flowi6 fl6;

	memset(&fl6, 0, sizeof(fl6));
	fl6.flowi6_iif = LOOPBACK_IFINDEX;
	fl6.flowi6_oif = oif;
	fl6.flowi6_mark = mark;
	fl6.daddr = iph->daddr;
	fl6.saddr = iph->saddr;
	fl6.flowlabel = ip6_flowinfo(iph);
	fl6.flowi6_uid = uid;

	dst = ip6_route_redirect(net, &fl6, &ipv6_hdr(skb)->saddr);
	rt6_do_redirect(dst, NULL, skb);
	dst_release(dst);
}
EXPORT_SYMBOL_GPL(ip6_redirect);

void ip6_redirect_no_header(struct sk_buff *skb, struct net *net, int oif,
			    u32 mark)
{
	const struct ipv6hdr *iph = ipv6_hdr(skb);
	const struct rd_msg *msg = (struct rd_msg *)icmp6_hdr(skb);
	struct dst_entry *dst;
	struct flowi6 fl6;

	memset(&fl6, 0, sizeof(fl6));
	fl6.flowi6_iif = LOOPBACK_IFINDEX;
	fl6.flowi6_oif = oif;
	fl6.flowi6_mark = mark;
	fl6.daddr = msg->dest;
	fl6.saddr = iph->daddr;
	fl6.flowi6_uid = sock_net_uid(net, NULL);

	dst = ip6_route_redirect(net, &fl6, &iph->saddr);
	rt6_do_redirect(dst, NULL, skb);
	dst_release(dst);
}

void ip6_sk_redirect(struct sk_buff *skb, struct sock *sk)
{
	ip6_redirect(skb, sock_net(sk), sk->sk_bound_dev_if, sk->sk_mark,
		     sk->sk_uid);
}
EXPORT_SYMBOL_GPL(ip6_sk_redirect);

static unsigned int ip6_default_advmss(const struct dst_entry *dst)
{
	struct net_device *dev = dst->dev;
	unsigned int mtu = dst_mtu(dst);
	struct net *net = dev_net(dev);

	mtu -= sizeof(struct ipv6hdr) + sizeof(struct tcphdr);

	if (mtu < net->ipv6.sysctl.ip6_rt_min_advmss)
		mtu = net->ipv6.sysctl.ip6_rt_min_advmss;

	/*
	 * Maximal non-jumbo IPv6 payload is IPV6_MAXPLEN and
	 * corresponding MSS is IPV6_MAXPLEN - tcp_header_size.
	 * IPV6_MAXPLEN is also valid and means: "any MSS,
	 * rely only on pmtu discovery"
	 */
	if (mtu > IPV6_MAXPLEN - sizeof(struct tcphdr))
		mtu = IPV6_MAXPLEN;
	return mtu;
}

static unsigned int ip6_mtu(const struct dst_entry *dst)
{
	const struct rt6_info *rt = (const struct rt6_info *)dst;
	unsigned int mtu = rt->rt6i_pmtu;
	struct inet6_dev *idev;

	if (mtu)
		goto out;

	mtu = dst_metric_raw(dst, RTAX_MTU);
	if (mtu)
		goto out;

	mtu = IPV6_MIN_MTU;

	rcu_read_lock();
	idev = __in6_dev_get(dst->dev);
	if (idev)
		mtu = idev->cnf.mtu6;
	rcu_read_unlock();

out:
	mtu = min_t(unsigned int, mtu, IP6_MAX_MTU);

	return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
}

struct dst_entry *icmp6_dst_alloc(struct net_device *dev,
				  struct flowi6 *fl6)
{
	struct dst_entry *dst;
	struct rt6_info *rt;
	struct inet6_dev *idev = in6_dev_get(dev);
	struct net *net = dev_net(dev);

	if (unlikely(!idev))
		return ERR_PTR(-ENODEV);

	rt = ip6_dst_alloc(net, dev, 0);
	if (unlikely(!rt)) {
		in6_dev_put(idev);
		dst = ERR_PTR(-ENOMEM);
		goto out;
	}

	rt->dst.flags |= DST_HOST;
	rt->dst.input = ip6_input;
	rt->dst.output  = ip6_output;
	rt->rt6i_gateway  = fl6->daddr;
	rt->rt6i_dst.addr = fl6->daddr;
	rt->rt6i_dst.plen = 128;
	rt->rt6i_idev     = idev;
	dst_metric_set(&rt->dst, RTAX_HOPLIMIT, 0);

	/* Add this dst into uncached_list so that rt6_disable_ip() can
	 * do proper release of the net_device
	 */
	rt6_uncached_list_add(rt);
	atomic_inc(&net->ipv6.rt6_stats->fib_rt_uncache);

	dst = xfrm_lookup(net, &rt->dst, flowi6_to_flowi(fl6), NULL, 0);

out:
	return dst;
}

static int ip6_dst_gc(struct dst_ops *ops)
{
	struct net *net = container_of(ops, struct net, ipv6.ip6_dst_ops);
	int rt_min_interval = net->ipv6.sysctl.ip6_rt_gc_min_interval;
	int rt_max_size = net->ipv6.sysctl.ip6_rt_max_size;
	int rt_elasticity = net->ipv6.sysctl.ip6_rt_gc_elasticity;
	int rt_gc_timeout = net->ipv6.sysctl.ip6_rt_gc_timeout;
	unsigned long rt_last_gc = net->ipv6.ip6_rt_last_gc;
	int entries;

	entries = dst_entries_get_fast(ops);
	if (time_after(rt_last_gc + rt_min_interval, jiffies) &&
	    entries <= rt_max_size)
		goto out;

	net->ipv6.ip6_rt_gc_expire++;
	fib6_run_gc(net->ipv6.ip6_rt_gc_expire, net, true);
	entries = dst_entries_get_slow(ops);
	if (entries < ops->gc_thresh)
		net->ipv6.ip6_rt_gc_expire = rt_gc_timeout>>1;
out:
	net->ipv6.ip6_rt_gc_expire -= net->ipv6.ip6_rt_gc_expire>>rt_elasticity;
	return entries > rt_max_size;
}

static int ip6_convert_metrics(struct mx6_config *mxc,
			       const struct fib6_config *cfg)
{
	struct net *net = cfg->fc_nlinfo.nl_net;
	bool ecn_ca = false;
	struct nlattr *nla;
	int remaining;
	u32 *mp;

	if (!cfg->fc_mx)
		return 0;

	mp = kzalloc(sizeof(u32) * RTAX_MAX, GFP_KERNEL);
	if (unlikely(!mp))
		return -ENOMEM;

	nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
		int type = nla_type(nla);
		u32 val;

		if (!type)
			continue;
		if (unlikely(type > RTAX_MAX))
			goto err;

		if (type == RTAX_CC_ALGO) {
			char tmp[TCP_CA_NAME_MAX];

			nla_strlcpy(tmp, nla, sizeof(tmp));
			val = tcp_ca_get_key_by_name(net, tmp, &ecn_ca);
			if (val == TCP_CA_UNSPEC)
				goto err;
		} else {
			val = nla_get_u32(nla);
		}
		if (type == RTAX_HOPLIMIT && val > 255)
			val = 255;
		if (type == RTAX_FEATURES && (val & ~RTAX_FEATURE_MASK))
			goto err;

		mp[type - 1] = val;
		__set_bit(type - 1, mxc->mx_valid);
	}

	if (ecn_ca) {
		__set_bit(RTAX_FEATURES - 1, mxc->mx_valid);
		mp[RTAX_FEATURES - 1] |= DST_FEATURE_ECN_CA;
	}

	mxc->mx = mp;
	return 0;
 err:
	kfree(mp);
	return -EINVAL;
}

static struct rt6_info *ip6_nh_lookup_table(struct net *net,
					    struct fib6_config *cfg,
					    const struct in6_addr *gw_addr,
					    u32 tbid, int flags)
{
	struct flowi6 fl6 = {
		.flowi6_oif = cfg->fc_ifindex,
		.daddr = *gw_addr,
		.saddr = cfg->fc_prefsrc,
	};
	struct fib6_table *table;
	struct rt6_info *rt;

	table = fib6_get_table(net, tbid);
	if (!table)
		return NULL;

	if (!ipv6_addr_any(&cfg->fc_prefsrc))
		flags |= RT6_LOOKUP_F_HAS_SADDR;

	flags |= RT6_LOOKUP_F_IGNORE_LINKSTATE;
	rt = ip6_pol_route(net, table, cfg->fc_ifindex, &fl6, flags);

	/* if table lookup failed, fall back to full lookup */
	if (rt == net->ipv6.ip6_null_entry) {
		ip6_rt_put(rt);
		rt = NULL;
	}

	return rt;
}

static int ip6_route_check_nh_onlink(struct net *net,
				     struct fib6_config *cfg,
				     struct net_device *dev,
				     struct netlink_ext_ack *extack)
{
	u32 tbid = l3mdev_fib_table(dev) ? : RT_TABLE_MAIN;
	const struct in6_addr *gw_addr = &cfg->fc_gateway;
	u32 flags = RTF_LOCAL | RTF_ANYCAST | RTF_REJECT;
	struct rt6_info *grt;
	int err;

	err = 0;
	grt = ip6_nh_lookup_table(net, cfg, gw_addr, tbid, 0);
	if (grt) {
		if (!grt->dst.error &&
		    (grt->rt6i_flags & flags || dev != grt->dst.dev)) {
			NL_SET_ERR_MSG(extack,
				       "Nexthop has invalid gateway or device mismatch");
			err = -EINVAL;
		}

		ip6_rt_put(grt);
	}

	return err;
}

static int ip6_route_check_nh(struct net *net,
			      struct fib6_config *cfg,
			      struct net_device **_dev,
			      struct inet6_dev **idev)
{
	const struct in6_addr *gw_addr = &cfg->fc_gateway;
	struct net_device *dev = _dev ? *_dev : NULL;
	struct rt6_info *grt = NULL;
	int err = -EHOSTUNREACH;

	if (cfg->fc_table) {
		int flags = RT6_LOOKUP_F_IFACE;

		grt = ip6_nh_lookup_table(net, cfg, gw_addr,
					  cfg->fc_table, flags);
		if (grt) {
			if (grt->rt6i_flags & RTF_GATEWAY ||
			    (dev && dev != grt->dst.dev)) {
				ip6_rt_put(grt);
				grt = NULL;
			}
		}
	}

	if (!grt)
		grt = rt6_lookup(net, gw_addr, NULL, cfg->fc_ifindex, 1);

	if (!grt)
		goto out;

	if (dev) {
		if (dev != grt->dst.dev) {
			ip6_rt_put(grt);
			goto out;
		}
	} else {
		*_dev = dev = grt->dst.dev;
		*idev = grt->rt6i_idev;
		dev_hold(dev);
		in6_dev_hold(grt->rt6i_idev);
	}

	if (!(grt->rt6i_flags & RTF_GATEWAY))
		err = 0;

	ip6_rt_put(grt);

out:
	return err;
}

static struct rt6_info *ip6_route_info_create(struct fib6_config *cfg,
					      struct netlink_ext_ack *extack)
{
	struct net *net = cfg->fc_nlinfo.nl_net;
	struct rt6_info *rt = NULL;
	struct net_device *dev = NULL;
	struct inet6_dev *idev = NULL;
	struct fib6_table *table;
	int addr_type;
	int err = -EINVAL;

	/* RTF_PCPU is an internal flag; can not be set by userspace */
	if (cfg->fc_flags & RTF_PCPU) {
		NL_SET_ERR_MSG(extack, "Userspace can not set RTF_PCPU");
		goto out;
	}

	/* RTF_CACHE is an internal flag; can not be set by userspace */
	if (cfg->fc_flags & RTF_CACHE) {
		NL_SET_ERR_MSG(extack, "Userspace can not set RTF_CACHE");
		goto out;
	}

	if (cfg->fc_dst_len > 128) {
		NL_SET_ERR_MSG(extack, "Invalid prefix length");
		goto out;
	}
	if (cfg->fc_src_len > 128) {
		NL_SET_ERR_MSG(extack, "Invalid source address length");
		goto out;
	}
#ifndef CONFIG_IPV6_SUBTREES
	if (cfg->fc_src_len) {
		NL_SET_ERR_MSG(extack,
			       "Specifying source address requires IPV6_SUBTREES to be enabled");
		goto out;
	}
#endif
	if (cfg->fc_ifindex) {
		err = -ENODEV;
		dev = dev_get_by_index(net, cfg->fc_ifindex);
		if (!dev)
			goto out;
		idev = in6_dev_get(dev);
		if (!idev)
			goto out;
	}

	if (cfg->fc_metric == 0)
		cfg->fc_metric = IP6_RT_PRIO_USER;

	if (cfg->fc_flags & RTNH_F_ONLINK) {
		if (!dev) {
			NL_SET_ERR_MSG(extack,
				       "Nexthop device required for onlink");
			err = -ENODEV;
			goto out;
		}

		if (!(dev->flags & IFF_UP)) {
			NL_SET_ERR_MSG(extack, "Nexthop device is not up");
			err = -ENETDOWN;
			goto out;
		}
	}

	err = -ENOBUFS;
	if (cfg->fc_nlinfo.nlh &&
	    !(cfg->fc_nlinfo.nlh->nlmsg_flags & NLM_F_CREATE)) {
		table = fib6_get_table(net, cfg->fc_table);
		if (!table) {
			pr_warn("NLM_F_CREATE should be specified when creating new route\n");
			table = fib6_new_table(net, cfg->fc_table);
		}
	} else {
		table = fib6_new_table(net, cfg->fc_table);
	}

	if (!table)
		goto out;

	rt = ip6_dst_alloc(net, NULL,
			   (cfg->fc_flags & RTF_ADDRCONF) ? 0 : DST_NOCOUNT);

	if (!rt) {
		err = -ENOMEM;
		goto out;
	}

	if (cfg->fc_flags & RTF_EXPIRES)
		rt6_set_expires(rt, jiffies +
				clock_t_to_jiffies(cfg->fc_expires));
	else
		rt6_clean_expires(rt);

	if (cfg->fc_protocol == RTPROT_UNSPEC)
		cfg->fc_protocol = RTPROT_BOOT;
	rt->rt6i_protocol = cfg->fc_protocol;

	addr_type = ipv6_addr_type(&cfg->fc_dst);

	if (addr_type & IPV6_ADDR_MULTICAST)
		rt->dst.input = ip6_mc_input;
	else if (cfg->fc_flags & RTF_LOCAL)
		rt->dst.input = ip6_input;
	else
		rt->dst.input = ip6_forward;

	rt->dst.output = ip6_output;

	if (cfg->fc_encap) {
		struct lwtunnel_state *lwtstate;

		err = lwtunnel_build_state(cfg->fc_encap_type,
					   cfg->fc_encap, AF_INET6, cfg,
					   &lwtstate, extack);
		if (err)
			goto out;
		rt->dst.lwtstate = lwtstate_get(lwtstate);
		if (lwtunnel_output_redirect(rt->dst.lwtstate)) {
			rt->dst.lwtstate->orig_output = rt->dst.output;
			rt->dst.output = lwtunnel_output;
		}
		if (lwtunnel_input_redirect(rt->dst.lwtstate)) {
			rt->dst.lwtstate->orig_input = rt->dst.input;
			rt->dst.input = lwtunnel_input;
		}
	}

	ipv6_addr_prefix(&rt->rt6i_dst.addr, &cfg->fc_dst, cfg->fc_dst_len);
	rt->rt6i_dst.plen = cfg->fc_dst_len;
	if (rt->rt6i_dst.plen == 128)
		rt->dst.flags |= DST_HOST;

#ifdef CONFIG_IPV6_SUBTREES
	ipv6_addr_prefix(&rt->rt6i_src.addr, &cfg->fc_src, cfg->fc_src_len);
	rt->rt6i_src.plen = cfg->fc_src_len;
#endif

	rt->rt6i_metric = cfg->fc_metric;
	rt->rt6i_nh_weight = 1;

	/* We cannot add true routes via loopback here,
	   they would result in kernel looping; promote them to reject routes
	 */
	if ((cfg->fc_flags & RTF_REJECT) ||
	    (dev && (dev->flags & IFF_LOOPBACK) &&
	     !(addr_type & IPV6_ADDR_LOOPBACK) &&
	     !(cfg->fc_flags & RTF_LOCAL))) {
		/* hold loopback dev/idev if we haven't done so. */
		if (dev != net->loopback_dev) {
			if (dev) {
				dev_put(dev);
				in6_dev_put(idev);
			}
			dev = net->loopback_dev;
			dev_hold(dev);
			idev = in6_dev_get(dev);
			if (!idev) {
				err = -ENODEV;
				goto out;
			}
		}
		rt->rt6i_flags = RTF_REJECT|RTF_NONEXTHOP;
		switch (cfg->fc_type) {
		case RTN_BLACKHOLE:
			rt->dst.error = -EINVAL;
			rt->dst.output = dst_discard_out;
			rt->dst.input = dst_discard;
			break;
		case RTN_PROHIBIT:
			rt->dst.error = -EACCES;
			rt->dst.output = ip6_pkt_prohibit_out;
			rt->dst.input = ip6_pkt_prohibit;
			break;
		case RTN_THROW:
		case RTN_UNREACHABLE:
		default:
			rt->dst.error = (cfg->fc_type == RTN_THROW) ? -EAGAIN
					: (cfg->fc_type == RTN_UNREACHABLE)
					? -EHOSTUNREACH : -ENETUNREACH;
			rt->dst.output = ip6_pkt_discard_out;
			rt->dst.input = ip6_pkt_discard;
			break;
		}
		goto install_route;
	}

	if (cfg->fc_flags & RTF_GATEWAY) {
		const struct in6_addr *gw_addr;
		int gwa_type;

		gw_addr = &cfg->fc_gateway;
		gwa_type = ipv6_addr_type(gw_addr);

		/* if gw_addr is local we will fail to detect this in case
		 * address is still TENTATIVE (DAD in progress). rt6_lookup()
		 * will return already-added prefix route via interface that
		 * prefix route was assigned to, which might be non-loopback.
		 */
		err = -EINVAL;
		if (ipv6_chk_addr_and_flags(net, gw_addr,
					    gwa_type & IPV6_ADDR_LINKLOCAL ?
					    dev : NULL, 0, 0)) {
			NL_SET_ERR_MSG(extack, "Invalid gateway address");
			goto out;
		}
		rt->rt6i_gateway = *gw_addr;

		if (gwa_type != (IPV6_ADDR_LINKLOCAL|IPV6_ADDR_UNICAST)) {
			/* IPv6 strictly inhibits using not link-local
			   addresses as nexthop address.
			   Otherwise, router will not able to send redirects.
			   It is very good, but in some (rare!) circumstances
			   (SIT, PtP, NBMA NOARP links) it is handy to allow
			   some exceptions. --ANK
			   We allow IPv4-mapped nexthops to support RFC4798-type
			   addressing
			 */
			if (!(gwa_type & (IPV6_ADDR_UNICAST |
					  IPV6_ADDR_MAPPED))) {
				NL_SET_ERR_MSG(extack,
					       "Invalid gateway address");
				goto out;
			}

			if (cfg->fc_flags & RTNH_F_ONLINK) {
				err = ip6_route_check_nh_onlink(net, cfg, dev,
								extack);
			} else {
				err = ip6_route_check_nh(net, cfg, &dev, &idev);
			}
			if (err)
				goto out;
		}
		err = -EINVAL;
		if (!dev) {
			NL_SET_ERR_MSG(extack, "Egress device not specified");
			goto out;
		} else if (dev->flags & IFF_LOOPBACK) {
			NL_SET_ERR_MSG(extack,
				       "Egress device can not be loopback device for this route");
			goto out;
		}
	}

	err = -ENODEV;
	if (!dev)
		goto out;

	if (!(dev->flags & IFF_UP)) {
		NL_SET_ERR_MSG(extack, "Nexthop device is not up");
		err = -ENETDOWN;
		goto out;
	}

	if (!ipv6_addr_any(&cfg->fc_prefsrc)) {
		if (!ipv6_chk_addr(net, &cfg->fc_prefsrc, dev, 0)) {
			NL_SET_ERR_MSG(extack, "Invalid source address");
			err = -EINVAL;
			goto out;
		}
		rt->rt6i_prefsrc.addr = cfg->fc_prefsrc;
		rt->rt6i_prefsrc.plen = 128;
	} else
		rt->rt6i_prefsrc.plen = 0;

	rt->rt6i_flags = cfg->fc_flags;

install_route:
	if (!(rt->rt6i_flags & (RTF_LOCAL | RTF_ANYCAST)) &&
	    !netif_carrier_ok(dev))
		rt->rt6i_nh_flags |= RTNH_F_LINKDOWN;
	rt->rt6i_nh_flags |= (cfg->fc_flags & RTNH_F_ONLINK);
	rt->dst.dev = dev;
	rt->rt6i_idev = idev;
	rt->rt6i_table = table;

	cfg->fc_nlinfo.nl_net = dev_net(dev);

	return rt;
out:
	if (dev)
		dev_put(dev);
	if (idev)
		in6_dev_put(idev);
	if (rt)
		dst_release_immediate(&rt->dst);

	return ERR_PTR(err);
}

int ip6_route_add(struct fib6_config *cfg,
		  struct netlink_ext_ack *extack)
{
	struct mx6_config mxc = { .mx = NULL, };
	struct rt6_info *rt;
	int err;

	rt = ip6_route_info_create(cfg, extack);
	if (IS_ERR(rt)) {
		err = PTR_ERR(rt);
		rt = NULL;
		goto out;
	}

	err = ip6_convert_metrics(&mxc, cfg);
	if (err)
		goto out;

	err = __ip6_ins_rt(rt, &cfg->fc_nlinfo, &mxc, extack);

	kfree(mxc.mx);

	return err;
out:
	if (rt)
		dst_release_immediate(&rt->dst);

	return err;
}

static int __ip6_del_rt(struct rt6_info *rt, struct nl_info *info)
{
	int err;
	struct fib6_table *table;
	struct net *net = dev_net(rt->dst.dev);

	if (rt == net->ipv6.ip6_null_entry) {
		err = -ENOENT;
		goto out;
	}

	table = rt->rt6i_table;
	spin_lock_bh(&table->tb6_lock);
	err = fib6_del(rt, info);
	spin_unlock_bh(&table->tb6_lock);

out:
	ip6_rt_put(rt);
	return err;
}

int ip6_del_rt(struct rt6_info *rt)
{
	struct nl_info info = {
		.nl_net = dev_net(rt->dst.dev),
	};
	return __ip6_del_rt(rt, &info);
}

static int __ip6_del_rt_siblings(struct rt6_info *rt, struct fib6_config *cfg)
{
	struct nl_info *info = &cfg->fc_nlinfo;
	struct net *net = info->nl_net;
	struct sk_buff *skb = NULL;
	struct fib6_table *table;
	int err = -ENOENT;

	if (rt == net->ipv6.ip6_null_entry)
		goto out_put;
	table = rt->rt6i_table;
	spin_lock_bh(&table->tb6_lock);

	if (rt->rt6i_nsiblings && cfg->fc_delete_all_nh) {
		struct rt6_info *sibling, *next_sibling;

		/* prefer to send a single notification with all hops */
		skb = nlmsg_new(rt6_nlmsg_size(rt), gfp_any());
		if (skb) {
			u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;

			if (rt6_fill_node(net, skb, rt,
					  NULL, NULL, 0, RTM_DELROUTE,
					  info->portid, seq, 0) < 0) {
				kfree_skb(skb);
				skb = NULL;
			} else
				info->skip_notify = 1;
		}

		list_for_each_entry_safe(sibling, next_sibling,
					 &rt->rt6i_siblings,
					 rt6i_siblings) {
			err = fib6_del(sibling, info);
			if (err)
				goto out_unlock;
		}
	}

	err = fib6_del(rt, info);
out_unlock:
	spin_unlock_bh(&table->tb6_lock);
out_put:
	ip6_rt_put(rt);

	if (skb) {
		rtnl_notify(skb, net, info->portid, RTNLGRP_IPV6_ROUTE,
			    info->nlh, gfp_any());
	}
	return err;
}

static int ip6_route_del(struct fib6_config *cfg,
			 struct netlink_ext_ack *extack)
{
	struct rt6_info *rt, *rt_cache;
	struct fib6_table *table;
	struct fib6_node *fn;
	int err = -ESRCH;

	table = fib6_get_table(cfg->fc_nlinfo.nl_net, cfg->fc_table);
	if (!table) {
		NL_SET_ERR_MSG(extack, "FIB table does not exist");
		return err;
	}

	rcu_read_lock();

	fn = fib6_locate(&table->tb6_root,
			 &cfg->fc_dst, cfg->fc_dst_len,
			 &cfg->fc_src, cfg->fc_src_len,
			 !(cfg->fc_flags & RTF_CACHE));

	if (fn) {
		for_each_fib6_node_rt_rcu(fn) {
			if (cfg->fc_flags & RTF_CACHE) {
				rt_cache = rt6_find_cached_rt(rt, &cfg->fc_dst,
							      &cfg->fc_src);
				if (!rt_cache)
					continue;
				rt = rt_cache;
			}
			if (cfg->fc_ifindex &&
			    (!rt->dst.dev ||
			     rt->dst.dev->ifindex != cfg->fc_ifindex))
				continue;
			if (cfg->fc_flags & RTF_GATEWAY &&
			    !ipv6_addr_equal(&cfg->fc_gateway, &rt->rt6i_gateway))
				continue;
			if (cfg->fc_metric && cfg->fc_metric != rt->rt6i_metric)
				continue;
			if (cfg->fc_protocol && cfg->fc_protocol != rt->rt6i_protocol)
				continue;
			if (!dst_hold_safe(&rt->dst))
				break;
			rcu_read_unlock();

			/* if gateway was specified only delete the one hop */
			if (cfg->fc_flags & RTF_GATEWAY)
				return __ip6_del_rt(rt, &cfg->fc_nlinfo);

			return __ip6_del_rt_siblings(rt, cfg);
		}
	}
	rcu_read_unlock();

	return err;
}

static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb)
{
	struct netevent_redirect netevent;
	struct rt6_info *rt, *nrt = NULL;
	struct ndisc_options ndopts;
	struct inet6_dev *in6_dev;
	struct neighbour *neigh;
	struct rd_msg *msg;
	int optlen, on_link;
	u8 *lladdr;

	optlen = skb_tail_pointer(skb) - skb_transport_header(skb);
	optlen -= sizeof(*msg);

	if (optlen < 0) {
		net_dbg_ratelimited("rt6_do_redirect: packet too short\n");
		return;
	}

	msg = (struct rd_msg *)icmp6_hdr(skb);

	if (ipv6_addr_is_multicast(&msg->dest)) {
		net_dbg_ratelimited("rt6_do_redirect: destination address is multicast\n");
		return;
	}

	on_link = 0;
	if (ipv6_addr_equal(&msg->dest, &msg->target)) {
		on_link = 1;
	} else if (ipv6_addr_type(&msg->target) !=
		   (IPV6_ADDR_UNICAST|IPV6_ADDR_LINKLOCAL)) {
		net_dbg_ratelimited("rt6_do_redirect: target address is not link-local unicast\n");
		return;
	}

	in6_dev = __in6_dev_get(skb->dev);
	if (!in6_dev)
		return;
	if (in6_dev->cnf.forwarding || !in6_dev->cnf.accept_redirects)
		return;

	/* RFC2461 8.1:
	 *	The IP source address of the Redirect MUST be the same as the current
	 *	first-hop router for the specified ICMP Destination Address.
	 */

	if (!ndisc_parse_options(skb->dev, msg->opt, optlen, &ndopts)) {
		net_dbg_ratelimited("rt6_redirect: invalid ND options\n");
		return;
	}

	lladdr = NULL;
	if (ndopts.nd_opts_tgt_lladdr) {
		lladdr = ndisc_opt_addr_data(ndopts.nd_opts_tgt_lladdr,
					     skb->dev);
		if (!lladdr) {
			net_dbg_ratelimited("rt6_redirect: invalid link-layer address length\n");
			return;
		}
	}

	rt = (struct rt6_info *) dst;
	if (rt->rt6i_flags & RTF_REJECT) {
		net_dbg_ratelimited("rt6_redirect: source isn't a valid nexthop for redirect target\n");
		return;
	}

	/* Redirect received -> path was valid.
	 * Look, redirects are sent only in response to data packets,
	 * so that this nexthop apparently is reachable. --ANK
	 */
	dst_confirm_neigh(&rt->dst, &ipv6_hdr(skb)->saddr);

	neigh = __neigh_lookup(&nd_tbl, &msg->target, skb->dev, 1);
	if (!neigh)
		return;

	/*
	 *	We have finally decided to accept it.
	 */

	ndisc_update(skb->dev, neigh, lladdr, NUD_STALE,
		     NEIGH_UPDATE_F_WEAK_OVERRIDE|
		     NEIGH_UPDATE_F_OVERRIDE|
		     (on_link ? 0 : (NEIGH_UPDATE_F_OVERRIDE_ISROUTER|
				     NEIGH_UPDATE_F_ISROUTER)),
		     NDISC_REDIRECT, &ndopts);

	nrt = ip6_rt_cache_alloc(rt, &msg->dest, NULL);
	if (!nrt)
		goto out;

	nrt->rt6i_flags = RTF_GATEWAY|RTF_UP|RTF_DYNAMIC|RTF_CACHE;
	if (on_link)
		nrt->rt6i_flags &= ~RTF_GATEWAY;

	nrt->rt6i_protocol = RTPROT_REDIRECT;
	nrt->rt6i_gateway = *(struct in6_addr *)neigh->primary_key;

	/* No need to remove rt from the exception table if rt is
	 * a cached route because rt6_insert_exception() will
	 * takes care of it
	 */
	if (rt6_insert_exception(nrt, rt)) {
		dst_release_immediate(&nrt->dst);
		goto out;
	}

	netevent.old = &rt->dst;
	netevent.new = &nrt->dst;
	netevent.daddr = &msg->dest;
	netevent.neigh = neigh;
	call_netevent_notifiers(NETEVENT_REDIRECT, &netevent);

out:
	neigh_release(neigh);
}

/*
 *	Misc support functions
 */

static void rt6_set_from(struct rt6_info *rt, struct rt6_info *from)
{
	BUG_ON(from->from);

	rt->rt6i_flags &= ~RTF_EXPIRES;
	dst_hold(&from->dst);
	rt->from = from;
	dst_init_metrics(&rt->dst, dst_metrics_ptr(&from->dst), true);
}

static void ip6_rt_copy_init(struct rt6_info *rt, struct rt6_info *ort)
{
	rt->dst.input = ort->dst.input;
	rt->dst.output = ort->dst.output;
	rt->rt6i_dst = ort->rt6i_dst;
	rt->dst.error = ort->dst.error;
	rt->rt6i_idev = ort->rt6i_idev;
	if (rt->rt6i_idev)
		in6_dev_hold(rt->rt6i_idev);
	rt->dst.lastuse = jiffies;
	rt->rt6i_gateway = ort->rt6i_gateway;
	rt->rt6i_flags = ort->rt6i_flags;
	rt6_set_from(rt, ort);
	rt->rt6i_metric = ort->rt6i_metric;
#ifdef CONFIG_IPV6_SUBTREES
	rt->rt6i_src = ort->rt6i_src;
#endif
	rt->rt6i_prefsrc = ort->rt6i_prefsrc;
	rt->rt6i_table = ort->rt6i_table;
	rt->dst.lwtstate = lwtstate_get(ort->dst.lwtstate);
}

#ifdef CONFIG_IPV6_ROUTE_INFO
static struct rt6_info *rt6_get_route_info(struct net *net,
					   const struct in6_addr *prefix, int prefixlen,
					   const struct in6_addr *gwaddr,
					   struct net_device *dev)
{
	u32 tb_id = l3mdev_fib_table(dev) ? : RT6_TABLE_INFO;
	int ifindex = dev->ifindex;
	struct fib6_node *fn;
	struct rt6_info *rt = NULL;
	struct fib6_table *table;

	table = fib6_get_table(net, tb_id);
	if (!table)
		return NULL;

	rcu_read_lock();
	fn = fib6_locate(&table->tb6_root, prefix, prefixlen, NULL, 0, true);
	if (!fn)
		goto out;

	for_each_fib6_node_rt_rcu(fn) {
		if (rt->dst.dev->ifindex != ifindex)
			continue;
		if ((rt->rt6i_flags & (RTF_ROUTEINFO|RTF_GATEWAY)) != (RTF_ROUTEINFO|RTF_GATEWAY))
			continue;
		if (!ipv6_addr_equal(&rt->rt6i_gateway, gwaddr))
			continue;
		ip6_hold_safe(NULL, &rt, false);
		break;
	}
out:
	rcu_read_unlock();
	return rt;
}

static struct rt6_info *rt6_add_route_info(struct net *net,
					   const struct in6_addr *prefix, int prefixlen,
					   const struct in6_addr *gwaddr,
					   struct net_device *dev,
					   unsigned int pref)
{
	struct fib6_config cfg = {
		.fc_metric	= IP6_RT_PRIO_USER,
		.fc_ifindex	= dev->ifindex,
		.fc_dst_len	= prefixlen,
		.fc_flags	= RTF_GATEWAY | RTF_ADDRCONF | RTF_ROUTEINFO |
				  RTF_UP | RTF_PREF(pref),
		.fc_protocol = RTPROT_RA,
		.fc_nlinfo.portid = 0,
		.fc_nlinfo.nlh = NULL,
		.fc_nlinfo.nl_net = net,
	};

	cfg.fc_table = l3mdev_fib_table(dev) ? : RT6_TABLE_INFO,
	cfg.fc_dst = *prefix;
	cfg.fc_gateway = *gwaddr;

	/* We should treat it as a default route if prefix length is 0. */
	if (!prefixlen)
		cfg.fc_flags |= RTF_DEFAULT;

	ip6_route_add(&cfg, NULL);

	return rt6_get_route_info(net, prefix, prefixlen, gwaddr, dev);
}
#endif

struct rt6_info *rt6_get_dflt_router(const struct in6_addr *addr, struct net_device *dev)
{
	u32 tb_id = l3mdev_fib_table(dev) ? : RT6_TABLE_DFLT;
	struct rt6_info *rt;
	struct fib6_table *table;

	table = fib6_get_table(dev_net(dev), tb_id);
	if (!table)
		return NULL;

	rcu_read_lock();
	for_each_fib6_node_rt_rcu(&table->tb6_root) {
		if (dev == rt->dst.dev &&
		    ((rt->rt6i_flags & (RTF_ADDRCONF | RTF_DEFAULT)) == (RTF_ADDRCONF | RTF_DEFAULT)) &&
		    ipv6_addr_equal(&rt->rt6i_gateway, addr))
			break;
	}
	if (rt)
		ip6_hold_safe(NULL, &rt, false);
	rcu_read_unlock();
	return rt;
}

struct rt6_info *rt6_add_dflt_router(const struct in6_addr *gwaddr,
				     struct net_device *dev,
				     unsigned int pref)
{
	struct fib6_config cfg = {
		.fc_table	= l3mdev_fib_table(dev) ? : RT6_TABLE_DFLT,
		.fc_metric	= IP6_RT_PRIO_USER,
		.fc_ifindex	= dev->ifindex,
		.fc_flags	= RTF_GATEWAY | RTF_ADDRCONF | RTF_DEFAULT |
				  RTF_UP | RTF_EXPIRES | RTF_PREF(pref),
		.fc_protocol = RTPROT_RA,
		.fc_nlinfo.portid = 0,
		.fc_nlinfo.nlh = NULL,
		.fc_nlinfo.nl_net = dev_net(dev),
	};

	cfg.fc_gateway = *gwaddr;

	if (!ip6_route_add(&cfg, NULL)) {
		struct fib6_table *table;

		table = fib6_get_table(dev_net(dev), cfg.fc_table);
		if (table)
			table->flags |= RT6_TABLE_HAS_DFLT_ROUTER;
	}

	return rt6_get_dflt_router(gwaddr, dev);
}

static void __rt6_purge_dflt_routers(struct fib6_table *table)
{
	struct rt6_info *rt;

restart:
	rcu_read_lock();
	for_each_fib6_node_rt_rcu(&table->tb6_root) {
		if (rt->rt6i_flags & (RTF_DEFAULT | RTF_ADDRCONF) &&
		    (!rt->rt6i_idev || rt->rt6i_idev->cnf.accept_ra != 2)) {
			if (dst_hold_safe(&rt->dst)) {
				rcu_read_unlock();
				ip6_del_rt(rt);
			} else {
				rcu_read_unlock();
			}
			goto restart;
		}
	}
	rcu_read_unlock();

	table->flags &= ~RT6_TABLE_HAS_DFLT_ROUTER;
}

void rt6_purge_dflt_routers(struct net *net)
{
	struct fib6_table *table;
	struct hlist_head *head;
	unsigned int h;

	rcu_read_lock();

	for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
		head = &net->ipv6.fib_table_hash[h];
		hlist_for_each_entry_rcu(table, head, tb6_hlist) {
			if (table->flags & RT6_TABLE_HAS_DFLT_ROUTER)
				__rt6_purge_dflt_routers(table);
		}
	}

	rcu_read_unlock();
}

static void rtmsg_to_fib6_config(struct net *net,
				 struct in6_rtmsg *rtmsg,
				 struct fib6_config *cfg)
{
	memset(cfg, 0, sizeof(*cfg));

	cfg->fc_table = l3mdev_fib_table_by_index(net, rtmsg->rtmsg_ifindex) ?
			 : RT6_TABLE_MAIN;
	cfg->fc_ifindex = rtmsg->rtmsg_ifindex;
	cfg->fc_metric = rtmsg->rtmsg_metric;
	cfg->fc_expires = rtmsg->rtmsg_info;
	cfg->fc_dst_len = rtmsg->rtmsg_dst_len;
	cfg->fc_src_len = rtmsg->rtmsg_src_len;
	cfg->fc_flags = rtmsg->rtmsg_flags;

	cfg->fc_nlinfo.nl_net = net;

	cfg->fc_dst = rtmsg->rtmsg_dst;
	cfg->fc_src = rtmsg->rtmsg_src;
	cfg->fc_gateway = rtmsg->rtmsg_gateway;
}

int ipv6_route_ioctl(struct net *net, unsigned int cmd, void __user *arg)
{
	struct fib6_config cfg;
	struct in6_rtmsg rtmsg;
	int err;

	switch (cmd) {
	case SIOCADDRT:		/* Add a route */
	case SIOCDELRT:		/* Delete a route */
		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
			return -EPERM;
		err = copy_from_user(&rtmsg, arg,
				     sizeof(struct in6_rtmsg));
		if (err)
			return -EFAULT;

		rtmsg_to_fib6_config(net, &rtmsg, &cfg);

		rtnl_lock();
		switch (cmd) {
		case SIOCADDRT:
			err = ip6_route_add(&cfg, NULL);
			break;
		case SIOCDELRT:
			err = ip6_route_del(&cfg, NULL);
			break;
		default:
			err = -EINVAL;
		}
		rtnl_unlock();

		return err;
	}

	return -EINVAL;
}

/*
 *	Drop the packet on the floor
 */

static int ip6_pkt_drop(struct sk_buff *skb, u8 code, int ipstats_mib_noroutes)
{
	int type;
	struct dst_entry *dst = skb_dst(skb);
	switch (ipstats_mib_noroutes) {
	case IPSTATS_MIB_INNOROUTES:
		type = ipv6_addr_type(&ipv6_hdr(skb)->daddr);
		if (type == IPV6_ADDR_ANY) {
			IP6_INC_STATS(dev_net(dst->dev), ip6_dst_idev(dst),
				      IPSTATS_MIB_INADDRERRORS);
			break;
		}
		/* FALLTHROUGH */
	case IPSTATS_MIB_OUTNOROUTES:
		IP6_INC_STATS(dev_net(dst->dev), ip6_dst_idev(dst),
			      ipstats_mib_noroutes);
		break;
	}
	icmpv6_send(skb, ICMPV6_DEST_UNREACH, code, 0);
	kfree_skb(skb);
	return 0;
}

static int ip6_pkt_discard(struct sk_buff *skb)
{
	return ip6_pkt_drop(skb, ICMPV6_NOROUTE, IPSTATS_MIB_INNOROUTES);
}

static int ip6_pkt_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb)
{
	skb->dev = skb_dst(skb)->dev;
	return ip6_pkt_drop(skb, ICMPV6_NOROUTE, IPSTATS_MIB_OUTNOROUTES);
}

static int ip6_pkt_prohibit(struct sk_buff *skb)
{
	return ip6_pkt_drop(skb, ICMPV6_ADM_PROHIBITED, IPSTATS_MIB_INNOROUTES);
}

static int ip6_pkt_prohibit_out(struct net *net, struct sock *sk, struct sk_buff *skb)
{
	skb->dev = skb_dst(skb)->dev;
	return ip6_pkt_drop(skb, ICMPV6_ADM_PROHIBITED, IPSTATS_MIB_OUTNOROUTES);
}

/*
 *	Allocate a dst for local (unicast / anycast) address.
 */

struct rt6_info *addrconf_dst_alloc(struct inet6_dev *idev,
				    const struct in6_addr *addr,
				    bool anycast)
{
	u32 tb_id;
	struct net *net = dev_net(idev->dev);
	struct net_device *dev = idev->dev;
	struct rt6_info *rt;