Subject: [PATCH RFC net-next 11/18] net: Initial nexthop code

From: [email-masked]
Date: Fri, 31 Aug 2018 17:49:46 -0700

From: David Ahern <[email-masked]>

Initial import of nexthop code.
- Add new RTM commands for nexthop objects.
- Add new uapi attributes for creating nexthops. Attributes are similar
  to the current nexthop attributes for routes.
- Add basic helpers for ipv4 and ipv6 references to nexthop data

Similar to routes nexthops are configured per namespace, so add
netns_nexthop struct and add it to struct net.

Signed-off-by: David Ahern <[email-masked]>
---
 include/net/net_namespace.h    |    2 +
 include/net/netns/nexthop.h    |   18 +
 include/net/nexthop.h          |  121 +++++
 include/uapi/linux/nexthop.h   |   56 +++
 include/uapi/linux/rtnetlink.h |    7 +
 net/ipv4/Makefile              |    2 +-
 net/ipv4/nexthop.c             | 1080 ++++++++++++++++++++++++++++++++++++++++
 security/selinux/nlmsgtab.c    |    5 +-
 8 files changed, 1289 insertions(+), 2 deletions(-)
 create mode 100644 include/net/netns/nexthop.h
 create mode 100644 include/net/nexthop.h
 create mode 100644 include/uapi/linux/nexthop.h
 create mode 100644 net/ipv4/nexthop.c

diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 9b5fdc50519a..d3d678814b93 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -19,6 +19,7 @@
 #include <net/netns/packet.h>
 #include <net/netns/ipv4.h>
 #include <net/netns/ipv6.h>
+#include <net/netns/nexthop.h>
 #include <net/netns/ieee802154_6lowpan.h>
 #include <net/netns/sctp.h>
 #include <net/netns/dccp.h>
@@ -105,6 +106,7 @@ struct net {
 	struct netns_mib	mib;
 	struct netns_packet	packet;
 	struct netns_unix	unx;
+	struct netns_nexthop	nexthop;
 	struct netns_ipv4	ipv4;
 #if IS_ENABLED(CONFIG_IPV6)
 	struct netns_ipv6	ipv6;
diff --git a/include/net/netns/nexthop.h b/include/net/netns/nexthop.h
new file mode 100644
index 000000000000..91627c35e9d3
--- /dev/null
+++ b/include/net/netns/nexthop.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * nexthops in net namespaces
+ */
+
+#ifndef __NETNS_NEXTHOP_H__
+#define __NETNS_NEXTHOP_H__
+
+#include <linux/rbtree.h>
+
+struct netns_nexthop {
+	struct rb_root		root;         /* tree of nexthops by id */
+	struct hlist_head	*devhash;     /* nexthops by device */
+
+	unsigned int		seq;		/* protected by rtnl_mutex */
+	u32			last_id_allocated;
+};
+#endif
diff --git a/include/net/nexthop.h b/include/net/nexthop.h
new file mode 100644
index 000000000000..1c59d04d1da6
--- /dev/null
+++ b/include/net/nexthop.h
@@ -0,0 +1,121 @@
+/*
+ * Generic nexthop implementation
+ *
+ * Copyright (C) 2017-18 Cumulus Networks
+ * Copyright (c) 2017-18 David Ahern <[email-masked]>
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __LINUX_NEXTHOP_H
+#define __LINUX_NEXTHOP_H
+
+#include <linux/netdevice.h>
+#include <linux/types.h>
+#include <net/ip_fib.h>
+#include <net/ip6_fib.h>
+#include <net/netlink.h>
+
+#define NEXTHOP_VALID_USER_FLAGS RTNH_F_ONLINK
+
+struct nexthop;
+
+struct nh_info {
+	struct hlist_node	dev_hash;
+	struct net		*net;
+	struct nexthop		*nh_parent;
+
+	u8			family;
+	u8			reject_nh:1,
+				has_gw:1,
+				unused:6;
+
+	union {
+		/* fib_nh used for device only nexthops as well */
+		struct fib_nh	fib_nh;
+		struct fib6_nh	fib6_nh;
+	};
+};
+
+struct nexthop {
+	struct rb_node		rb_node;
+	struct list_head	fi_list;    /* v4 entries using nh */
+	struct list_head	f6i_list;   /* v6 entries using nh */
+
+	u32			id;
+
+	u8			protocol;
+	u8			nh_flags;
+
+	refcount_t		refcnt;
+	struct rcu_head		rcu;
+
+	union {
+		struct nh_info	__rcu *nh_info;
+	};
+};
+
+struct nh_config {
+	u8		nh_family;
+	u8		nh_scope;
+	u8		nh_protocol;
+	u8		nh_blackhole;
+	u32		nh_flags;
+
+	u32		nh_id;
+	u32		tclassid;
+
+	int		nh_ifindex;
+	struct net_device *dev;
+	u32		nh_table;
+	union {
+		__be32		ipv4;
+		struct in6_addr	ipv6;
+	} gw;
+
+	u32		nlflags;
+	struct nl_info	nlinfo;
+};
+
+void nexthop_get(struct nexthop *nh);
+void nexthop_put(struct nexthop *nh);
+
+/* caller is holding rtnl; no reference taken to nexthop */
+struct nexthop *nexthop_find_by_id(struct net *net, u32 id);
+
+static inline bool nexthop_cmp(struct nexthop *nh1, struct nexthop *nh2)
+{
+	return nh1 == nh2;
+}
+
+static inline int nexthop_num_path(struct nexthop *nh)
+{
+	return 1;
+}
+
+/* called with rcu lock */
+static inline bool nexthop_has_gw(struct nexthop *nh)
+{
+	struct nh_info *nhi;
+
+	nhi = rcu_dereference(nh->nh_info);
+	return !!nhi->has_gw;
+}
+
+/* called with rcu lock */
+static inline bool nexthop_is_blackhole(struct nexthop *nh)
+{
+	struct nh_info *nhi;
+
+	nhi = rcu_dereference(nh->nh_info);
+	return !!nhi->reject_nh;
+}
+#endif
diff --git a/include/uapi/linux/nexthop.h b/include/uapi/linux/nexthop.h
new file mode 100644
index 000000000000..f40ef188b529
--- /dev/null
+++ b/include/uapi/linux/nexthop.h
@@ -0,0 +1,56 @@
+#ifndef _UAPI_LINUX_NEXTHOP_H
+#define _UAPI_LINUX_NEXTHOP_H
+
+#include <linux/types.h>
+
+struct nhmsg {
+	unsigned char	nh_family;
+	unsigned char	nh_scope;     /* one of RT_SCOPE */
+	unsigned char	nh_protocol;  /* Routing protocol that installed nh */
+	unsigned char	resvd;
+	unsigned int	nh_flags;     /* RTNH_F flags */
+};
+
+struct nexthop_grp {
+	__u32	id;
+	__u32	weight;
+};
+
+enum {
+	NEXTHOP_GRP_TYPE_MPATH,  /* default type if not specified */
+	__NEXTHOP_GRP_TYPE_MAX,
+};
+
+#define NEXTHOP_GRP_TYPE_MAX (__NEXTHOP_GRP_TYPE_MAX - 1)
+
+
+/* NHA_ID	32-bit id for nexthop. id must be greater than 0.
+ *		id == 0 means assign an unused id.
+ */
+enum {
+	NHA_UNSPEC,
+	NHA_ID,		/* u32 */
+	NHA_GROUP,	/* array of nexthop_grp */
+	NHA_GROUP_TYPE,	/* u16 one of NEXTHOP_GRP_TYPE;
+			 * default is NEXTHOP_GRP_TYPE_MPATH */
+
+	/* if NHA_GROUP attribute is added, no other attributes can be set */
+
+	NHA_BLACKHOLE,	/* flag; nexthop used to blackhole packets */
+	NHA_OIF,	/* u32 */
+	NHA_FLOW,	/* u32 */
+
+	NHA_TABLE_ID,	/* u32 - table id to validate gateway */
+	NHA_GATEWAY,	/* be32 (IPv4) or in6_addr (IPv6) gw address */
+
+	/* Dump control attributes */
+	NHA_GROUPS,	/* flag; only return nexthop groups in dump */
+	NHA_MASTER,	/* u32; only return nexthops with given master dev */
+
+	NHA_SADDR,	/* return only: IPv4 or IPv6 source address */
+
+	__NHA_MAX,
+};
+
+#define NHA_MAX	(__NHA_MAX - 1)
+#endif
diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h
index 46399367627f..4a0615797e5e 100644
--- a/include/uapi/linux/rtnetlink.h
+++ b/include/uapi/linux/rtnetlink.h
@@ -157,6 +157,13 @@ enum {
 	RTM_GETCHAIN,
 #define RTM_GETCHAIN RTM_GETCHAIN
 
+	RTM_NEWNEXTHOP = 104,
+#define RTM_NEWNEXTHOP	RTM_NEWNEXTHOP
+	RTM_DELNEXTHOP,
+#define RTM_DELNEXTHOP	RTM_DELNEXTHOP
+	RTM_GETNEXTHOP,
+#define RTM_GETNEXTHOP	RTM_GETNEXTHOP
+
 	__RTM_MAX,
 #define RTM_MAX		(((__RTM_MAX + 3) & ~3) - 1)
 };
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index 7446b98661d8..2ee5129a070c 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -14,7 +14,7 @@ obj-y     := route.o inetpeer.o protocol.o \
 	     udp_offload.o arp.o icmp.o devinet.o af_inet.o igmp.o \
 	     fib_frontend.o fib_semantics.o fib_trie.o fib_notifier.o \
 	     inet_fragment.o ping.o ip_tunnel_core.o gre_offload.o \
-	     metrics.o netlink.o
+	     metrics.o netlink.o nexthop.o
 
 obj-$(CONFIG_BPFILTER) += bpfilter/
 
diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
new file mode 100644
index 000000000000..24c4aa383c9d
--- /dev/null
+++ b/net/ipv4/nexthop.c
@@ -0,0 +1,1080 @@
+/* Generic nexthop implementation
+ *
+ * Copyright (C) 2017-18 Cumulus Networks
+ * Copyright (c) 2017-18 David Ahern <[email-masked]>
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/inetdevice.h>
+#include <linux/nexthop.h>
+#include <linux/rtnetlink.h>
+#include <linux/slab.h>
+#include <net/nexthop.h>
+#include <net/route.h>
+#include <net/ip6_route.h>
+
+static void remove_nexthop(struct net *net, struct nexthop *nh,
+			   bool skip_fib, struct nl_info *nlinfo);
+
+#define NH_DEV_HASHBITS  8
+#define NH_DEV_HASHSIZE (1U << NH_DEV_HASHBITS)
+
+static const struct nla_policy rtm_nh_policy[NHA_MAX + 1] = {
+	[NHA_ID]		= { .type = NLA_U32 },
+	[NHA_OIF]		= { .type = NLA_U32 },
+	[NHA_FLOW]		= { .type = NLA_U32 },
+	[NHA_TABLE_ID]		= { .type = NLA_U32 },
+	[NHA_BLACKHOLE]		= { .type = NLA_FLAG },
+	[NHA_MASTER]		= { .type = NLA_U32 },
+};
+
+static unsigned int nh_dev_hashfn(unsigned int val)
+{
+	unsigned int mask = NH_DEV_HASHSIZE - 1;
+
+	return (val ^
+		(val >> NH_DEV_HASHBITS) ^
+		(val >> (NH_DEV_HASHBITS * 2))) & mask;
+}
+
+static void nexthop_devhash_add(struct net *net, struct nh_info *nhi)
+{
+	struct hlist_head *head;
+	struct net_device *dev;
+	unsigned int hash;
+
+	if (nhi->family == AF_INET6)
+		dev = nhi->fib6_nh.nh_dev;
+	else
+		dev = nhi->fib_nh.nh_dev;
+
+	WARN_ON(!dev);
+
+	hash = nh_dev_hashfn(dev->ifindex);
+	head = &net->nexthop.devhash[hash];
+	hlist_add_head(&nhi->dev_hash, head);
+}
+
+static void nexthop_free_rcu(struct rcu_head *head)
+{
+	struct nexthop *nh = container_of(head, struct nexthop, rcu);
+	struct nh_info *nhi;
+
+	nhi = rcu_dereference_raw(nh->nh_info);
+	switch (nhi->family) {
+	case AF_INET:
+	case AF_UNSPEC:
+		fib_nh_release(nhi->net, &nhi->fib_nh);
+		break;
+	case AF_INET6:
+		fib6_nh_release(&nhi->fib6_nh);
+		break;
+	}
+	kfree(nhi);
+
+	kfree(nh);
+}
+
+static struct nexthop *nexthop_alloc(void)
+{
+	return kzalloc(sizeof(struct nexthop), GFP_KERNEL);
+}
+
+static void nh_base_seq_inc(struct net *net)
+{
+	while (++net->nexthop.seq == 0)
+		;
+}
+
+void nexthop_put(struct nexthop *nh)
+{
+	if (refcount_dec_and_test(&nh->refcnt))
+		call_rcu(&nh->rcu, nexthop_free_rcu);
+}
+
+void nexthop_get(struct nexthop *nh)
+{
+	refcount_inc(&nh->refcnt);
+}
+
+/* no reference taken; rcu lock or rtnl must be held */
+struct nexthop *nexthop_find_by_id(struct net *net, u32 id)
+{
+	struct rb_node **pp, *parent = NULL, *next;
+
+	pp = &net->nexthop.root.rb_node;
+	while (1) {
+		struct nexthop *nh;
+
+		next = rtnl_dereference(*pp);
+		if (!next)
+			break;
+		parent = next;
+
+		nh = rb_entry(parent, struct nexthop, rb_node);
+		if (id < nh->id)
+			pp = &next->rb_left;
+		else if (id > nh->id)
+			pp = &next->rb_right;
+		else
+			return nh;
+	}
+	return NULL;
+}
+
+/* find an unused id - used for auto id allocation
+ * called with rtnl lock held
+ */
+static u32 nh_find_unused_id(struct net *net)
+{
+	u32 id_start = net->nexthop.last_id_allocated;
+
+	while (1) {
+		net->nexthop.last_id_allocated++;
+		if (net->nexthop.last_id_allocated == id_start)
+			break;
+
+		if (!nexthop_find_by_id(net, net->nexthop.last_id_allocated))
+			return net->nexthop.last_id_allocated;
+	}
+	return 0;
+}
+
+static size_t nh_nlmsg_size_ipv6(struct nh_info *nhi)
+{
+	size_t sz = 0;
+
+	sz = nla_total_size(sizeof(nhi->fib6_nh.nh_gw));
+
+	return sz;
+}
+
+static size_t nh_nlmsg_size_ipv4(struct nh_info *nhi)
+{
+	size_t sz;
+
+	sz = nla_total_size(4)     /* NHA_GATEWAY */
+#ifdef CONFIG_IP_ROUTE_CLASSID
+	     + nla_total_size(4)   /* NHA_FLOW */
+#endif
+	     + nla_total_size(4);  /* NHA_SADDR_IPV4 */
+
+	return sz;
+}
+
+static size_t nh_nlmsg_size(struct nexthop *nh)
+{
+	struct nh_info *nhi = rtnl_dereference(nh->nh_info);
+	size_t sz = nla_total_size(4);    /* NHA_ID */
+
+	/* covers NHA_BLACKHOLE since NHA_OIF and BLACKHOLE
+	 * are mutually exclusive
+	 */
+	sz += nla_total_size(4);  /* NHA_OIF */
+
+	if (nhi->family == AF_INET)
+		sz += nh_nlmsg_size_ipv4(nhi);
+
+	else if (nhi->family == AF_INET6)
+		sz += nh_nlmsg_size_ipv6(nhi);
+
+	return sz;
+}
+
+static const struct net_device *nh_info_dev(const struct nh_info *nhi)
+{
+	switch (nhi->family) {
+	case AF_INET:
+	case AF_UNSPEC:  /* dev only re-uses IPv4 struct */
+		return nhi->fib_nh.nh_dev;
+	case AF_INET6:
+		return nhi->fib6_nh.nh_dev;
+	}
+	return NULL;
+}
+
+static bool nh_info_uses_dev(const struct nh_info *nhi,
+			     const struct net_device *dev)
+{
+	const struct net_device *nh_dev;
+
+	nh_dev = nh_info_dev(nhi);
+	if (nh_dev == dev || l3mdev_master_dev_rcu(nh_dev) == dev)
+		return true;
+
+	return false;
+}
+
+bool nexthop_uses_dev(const struct nexthop *nh, const struct net_device *dev)
+{
+	const struct nh_info *nhi;
+	bool dev_match = false;
+
+	nhi = rcu_dereference(nh->nh_info);
+	dev_match = nh_info_uses_dev(nhi, dev);
+
+	return dev_match;
+}
+
+static int nh_fill_node(struct sk_buff *skb, struct nexthop *nh,
+			int event, u32 portid, u32 seq, unsigned int nlflags)
+{
+	const struct net_device *dev;
+	struct fib6_nh *fib6_nh;
+	struct fib_nh *fib_nh;
+	struct nlmsghdr *nlh;
+	struct nh_info *nhi;
+	struct nhmsg *nhm;
+
+	nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nhm), nlflags);
+	if (!nlh)
+		return -EMSGSIZE;
+
+	nhm = nlmsg_data(nlh);
+	nhm->nh_family = AF_UNSPEC;
+	nhm->nh_flags = nh->nh_flags;
+	nhm->nh_protocol = nh->protocol;
+	nhm->nh_scope = 0;
+	nhm->resvd = 0;
+
+	if (nla_put_u32(skb, NHA_ID, nh->id))
+		goto nla_put_failure;
+
+	nhi = rtnl_dereference(nh->nh_info);
+	if (nhi->reject_nh && nla_put_flag(skb, NHA_BLACKHOLE))
+		goto nla_put_failure;
+
+	dev = nh_info_dev(nhi);
+	if (dev && nla_put_u32(skb, NHA_OIF, dev->ifindex))
+		goto nla_put_failure;
+
+	nhm->nh_family = nhi->family;
+	switch (nhi->family) {
+	case AF_INET:
+		fib_nh = &nhi->fib_nh;
+
+		nhm->nh_scope = fib_nh->nh_scope;
+		if (nla_put_u32(skb, NHA_GATEWAY, fib_nh->nh_gw))
+			goto nla_put_failure;
+		if (nla_put_u32(skb, NHA_SADDR, fib_nh->nh_saddr))
+			goto nla_put_failure;
+#ifdef CONFIG_IP_ROUTE_CLASSID
+		if (fib_nh->nh_tclassid &&
+		    nla_put_u32(skb, NHA_FLOW, fib_nh->nh_tclassid))
+			goto nla_put_failure;
+#endif
+		break;
+
+	case AF_INET6:
+		fib6_nh = &nhi->fib6_nh;
+		if (nla_put_in6_addr(skb, NHA_GATEWAY, &fib6_nh->nh_gw) < 0)
+			goto nla_put_failure;
+		break;
+	}
+
+	nlmsg_end(skb, nlh);
+	return 0;
+
+nla_put_failure:
+	return -EMSGSIZE;
+}
+
+static void nexthop_notify(int event, struct nexthop *nh, struct nl_info *info)
+{
+	unsigned int nlflags = info->nlh ? info->nlh->nlmsg_flags : 0;
+	u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
+	struct sk_buff *skb;
+	int err = -ENOBUFS;
+
+	skb = nlmsg_new(nh_nlmsg_size(nh), gfp_any());
+	if (!skb)
+		goto errout;
+
+	err = nh_fill_node(skb, nh, event, info->portid, seq, nlflags);
+	if (err < 0) {
+		/* -EMSGSIZE implies BUG in nh_nlmsg_size() */
+		WARN_ON(err == -EMSGSIZE);
+		kfree_skb(skb);
+		goto errout;
+	}
+
+	rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
+		    info->nlh, gfp_any());
+	return;
+errout:
+	if (err < 0)
+		rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
+}
+
+/* called on insert failure too */
+static void __remove_nexthop(struct net *net, struct nexthop *nh,
+			     bool skip_fib, struct nl_info *nlinfo)
+{
+	const struct net_device *dev;
+	struct nh_info *nhi;
+
+	nhi = rtnl_dereference(nh->nh_info);
+	dev = nh_info_dev(nhi);
+	if (dev)
+		hlist_del(&nhi->dev_hash);
+}
+
+static void remove_nexthop(struct net *net, struct nexthop *nh,
+			   bool skip_fib, struct nl_info *nlinfo)
+{
+	/* remove from the tree */
+	rb_erase(&nh->rb_node, &net->nexthop.root);
+
+	__remove_nexthop(net, nh, skip_fib, nlinfo);
+
+	nh_base_seq_inc(net);
+
+	nexthop_put(nh);
+
+	nexthop_notify(RTM_DELNEXTHOP, nh, nlinfo);
+}
+
+static int replace_nexthop(struct net *net, struct nexthop *old,
+			   struct nexthop *new, struct netlink_ext_ack *extack)
+{
+	struct nh_info *oldi, *newi;
+
+	oldi = rtnl_dereference(old->nh_info);
+	newi = rtnl_dereference(new->nh_info);
+	rcu_assign_pointer(old->nh_info, newi);
+	rcu_assign_pointer(new->nh_info, oldi);
+
+	newi->nh_parent = old;
+	oldi->nh_parent = new;
+
+	old->protocol = new->protocol;
+	old->nh_flags = new->nh_flags;
+
+	rt_cache_flush(net);
+	// TO-DO: ipv6 equiv
+
+	__remove_nexthop(net, new, true, NULL);
+	nexthop_put(new);
+
+	return 0;
+}
+
+/* called with rtnl_lock held */
+static int insert_nexthop(struct net *net, struct nexthop *new_nh,
+			  struct nh_config *cfg, struct netlink_ext_ack *extack)
+{
+	struct rb_node **pp, *parent = NULL, *next;
+	struct rb_root *root = &net->nexthop.root;
+	bool replace = !!(cfg->nlflags & NLM_F_REPLACE);
+	bool create = !!(cfg->nlflags & NLM_F_CREATE);
+	u32 new_id = new_nh->id;
+	int rc = -EEXIST;
+
+	pp = &root->rb_node;
+	while (1) {
+		struct nexthop *nh;
+
+		next = rtnl_dereference(*pp);
+		if (!next)
+			break;
+
+		parent = next;
+
+		nh = rb_entry(parent, struct nexthop, rb_node);
+		if (new_id < nh->id) {
+			pp = &next->rb_left;
+		} else if (new_id > nh->id) {
+			pp = &next->rb_right;
+		} else if (replace) {
+			rc = replace_nexthop(net, nh, new_nh, extack);
+			if (!rc)
+				new_nh = nh; /* send notification with old nh */
+			goto out;
+		} else {
+			/* id already exists and not a replace */
+			goto out;
+		}
+	}
+
+	if (replace && !create) {
+		NL_SET_ERR_MSG(extack, "Replace specified without create and no entry exists");
+		rc = -ENOENT;
+		goto out;
+	}
+
+	rb_link_node_rcu(&new_nh->rb_node, parent, pp);
+	rb_insert_color(&new_nh->rb_node, root);
+	rc = 0;
+out:
+	if (!rc) {
+		nh_base_seq_inc(net);
+		nexthop_notify(RTM_NEWNEXTHOP, new_nh, &cfg->nlinfo);
+	}
+
+	return rc;
+}
+
+/* rtnl */
+/* remove all nexthops tied to a device being deleted */
+static void nexthop_flush_dev(struct net_device *dev)
+{
+	unsigned int hash = nh_dev_hashfn(dev->ifindex);
+	struct net *net = dev_net(dev);
+	struct hlist_head *head = &net->nexthop.devhash[hash];
+	struct nl_info nlinfo = {
+		.nl_net = net,
+	};
+	struct hlist_node *n;
+	struct nh_info *nhi;
+
+	hlist_for_each_entry_safe(nhi, n, head, dev_hash) {
+		if (nh_info_dev(nhi) != dev)
+			continue;
+
+		remove_nexthop(net, nhi->nh_parent, false, &nlinfo);
+	}
+}
+
+/* rtnl */
+static void flush_all_nexthops(struct net *net)
+{
+	struct rb_root *root = &net->nexthop.root;
+	struct rb_node *node;
+	struct nexthop *nh;
+	struct nl_info nlinfo = {
+		.nl_net = net,
+	};
+
+	while ((node = rb_first(root))) {
+		nh = rb_entry(node, struct nexthop, rb_node);
+		remove_nexthop(net, nh, true, &nlinfo);
+		cond_resched();
+	}
+}
+
+static int nh_check_attr(struct nhmsg *nhm, struct nlattr *tb[],
+			 struct net *net, struct netlink_ext_ack *extack)
+{
+	int err = -EINVAL;
+
+	if (nhm->nh_flags & ~NEXTHOP_VALID_USER_FLAGS) {
+		NL_SET_ERR_MSG(extack,
+			       "Invalid nexthop flags in ancillary header");
+		goto out;
+	}
+
+	err = 0;
+out:
+	return err;
+}
+
+static int rtm_to_nh_config(struct net *net, struct sk_buff *skb,
+			    struct nlmsghdr *nlh, struct nh_config *cfg,
+			    struct netlink_ext_ack *extack)
+{
+	struct nhmsg *nhm = nlmsg_data(nlh);
+	struct nlattr *tb[NHA_MAX + 1];
+	int err;
+
+	err = nlmsg_parse(nlh, sizeof(*nhm), tb, NHA_MAX,
+			  rtm_nh_policy, extack);
+	if (err < 0)
+		return err;
+
+	if (nhm->resvd) {
+		NL_SET_ERR_MSG(extack, "Invalid value in reserved field of ancillary header");
+		return -EINVAL;
+	}
+
+	err = nh_check_attr(nhm, tb, net, extack);
+	if (err < 0)
+		return err;
+
+	memset(cfg, 0, sizeof(*cfg));
+	cfg->nlflags = nlh->nlmsg_flags;
+	cfg->nlinfo.portid = NETLINK_CB(skb).portid;
+	cfg->nlinfo.nlh = nlh;
+	cfg->nlinfo.nl_net = net;
+
+	cfg->nh_family = nhm->nh_family;
+	cfg->nh_protocol = nhm->nh_protocol;
+	cfg->nh_flags = nhm->nh_flags;
+	cfg->nh_scope = nhm->nh_scope;
+
+	if (tb[NHA_ID])
+		cfg->nh_id = nla_get_u32(tb[NHA_ID]);
+
+	if (tb[NHA_OIF]) {
+		cfg->nh_ifindex = nla_get_u32(tb[NHA_OIF]);
+
+		if (cfg->nh_ifindex)
+			cfg->dev = __dev_get_by_index(net, cfg->nh_ifindex);
+
+		if (!cfg->dev) {
+			NL_SET_ERR_MSG(extack, "Invalid device index");
+			goto out;
+		} else if (!(cfg->dev->flags & IFF_UP)) {
+			NL_SET_ERR_MSG(extack, "Nexthop device is not up");
+			err = -ENETDOWN;
+			goto out;
+		} else if (!netif_carrier_ok(cfg->dev)) {
+			NL_SET_ERR_MSG(extack,
+				       "Carrier for nexthop device is down");
+			err = -ENETDOWN;
+			goto out;
+		}
+
+		cfg->nh_table = l3mdev_fib_table(cfg->dev);
+	}
+
+	if (tb[NHA_TABLE_ID])
+		cfg->nh_table = nla_get_u32(tb[NHA_TABLE_ID]);
+
+	err = -EINVAL;
+	if (tb[NHA_FLOW]) {
+#ifndef CONFIG_IP_ROUTE_CLASSID
+		NL_SET_ERR_MSG(extack, "Classid not enabled in kernel");
+		goto out;
+#else
+		cfg->tclassid = nla_get_u32(tb[NHA_FLOW]);
+#endif
+	}
+
+	if (tb[NHA_GATEWAY]) {
+		struct nlattr *gwa = tb[NHA_GATEWAY];
+
+		switch (cfg->nh_family) {
+		case AF_INET:
+			if (nla_len(gwa) != sizeof(u32)) {
+				NL_SET_ERR_MSG(extack, "Invalid gateway");
+				goto out;
+			}
+			cfg->gw.ipv4 = nla_get_be32(gwa);
+			break;
+		case AF_INET6:
+			if (nla_len(gwa) != sizeof(struct in6_addr)) {
+				NL_SET_ERR_MSG(extack, "Invalid gateway");
+				goto out;
+			}
+			cfg->gw.ipv6 = nla_get_in6_addr(gwa);
+			break;
+		default:
+			NL_SET_ERR_MSG(extack,
+				       "Unknown address family for gateway");
+			goto out;
+		}
+	} else {
+		cfg->nh_family = AF_UNSPEC;
+
+		/* device only nexthop (no gateway) */
+		if (cfg->nh_flags & RTNH_F_ONLINK) {
+			NL_SET_ERR_MSG(extack,
+				       "ONLINK flag can not be set for nexthop without a gateway");
+			goto out;
+		}
+		cfg->nh_scope = RT_SCOPE_LINK;
+	}
+
+	if (tb[NHA_BLACKHOLE]) {
+		if (tb[NHA_GATEWAY]) {
+			NL_SET_ERR_MSG(extack,
+				       "Blackhole attribute can not be used with gateway");
+			goto out;
+		}
+
+		cfg->nh_blackhole = 1;
+	}
+
+	if (cfg->tclassid && cfg->nh_family != AF_INET) {
+		NL_SET_ERR_MSG(extack,
+			       "FLOW attribute only relevant for IPv4 nexthops");
+		goto out;
+	}
+
+	err = 0;
+out:
+	return err;
+}
+
+/* rtnl */
+static int rtm_get_nexthop(struct sk_buff *in_skb, struct nlmsghdr *nlh,
+			   struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(in_skb->sk);
+	struct nhmsg *nhm = nlmsg_data(nlh);
+	struct nlattr *tb[NHA_MAX + 1];
+	struct sk_buff *skb = NULL;
+	struct nexthop *nh;
+	int err;
+	u32 id;
+
+	err = nlmsg_parse(nlh, sizeof(*nhm), tb, NHA_MAX,
+			  rtm_nh_policy, extack);
+	if (err < 0)
+		goto out;
+
+	err = -EINVAL;
+	if (!tb[NHA_ID]) {
+		NL_SET_ERR_MSG(extack, "Nexthop id is missing");
+		goto out;
+	}
+	id = nla_get_u32(tb[NHA_ID]);
+	if (!id) {
+		NL_SET_ERR_MSG(extack, "Invalid nexthop id");
+		goto out;
+	}
+
+	err = -ENOBUFS;
+	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
+	if (!skb)
+		goto out;
+
+	err = -ENOENT;
+	nh = nexthop_find_by_id(net, id);
+	if (!nh)
+		goto errout_free;
+
+	err = nh_fill_node(skb, nh, RTM_NEWNEXTHOP, NETLINK_CB(in_skb).portid,
+			   nlh->nlmsg_seq, 0);
+	if (err < 0)
+		goto errout_free;
+
+	err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
+out:
+	return err;
+errout_free:
+	kfree_skb(skb);
+	goto out;
+}
+
+/* rtnl */
+static int rtm_del_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh,
+			   struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(skb->sk);
+	struct nlattr *tb[NHA_MAX + 1];
+	struct nl_info nlinfo = {
+		.nlh = nlh,
+		.nl_net = net,
+		.portid = NETLINK_CB(skb).portid,
+	};
+	struct nexthop *nh;
+	struct nhmsg *nhm;
+	int err, i;
+	u32 id;
+
+	err = nlmsg_parse(nlh, sizeof(*nhm), tb, NHA_MAX,
+			  rtm_nh_policy, extack);
+	if (err < 0)
+		return err;
+
+	nhm = nlmsg_data(nlh);
+
+	/* validate expected attribute and check for unexpected attributes */
+	for (i = 1; i < __NHA_MAX; ++i) {
+		switch (i) {
+		case NHA_ID:
+			if (!tb[NHA_ID]) {
+				NL_SET_ERR_MSG(extack, "Nexthop id is missing");
+				return -EINVAL;
+			}
+			break;
+		default:
+			if (!tb[i])
+				break;
+
+			NL_SET_ERR_MSG_ATTR(extack, tb[i],
+					    "Unexpected attribute in request");
+			return -EINVAL;
+		}
+	}
+
+	id = nla_get_u32(tb[NHA_ID]);
+	nh = nexthop_find_by_id(net, id);
+	if (!nh)
+		return -ENOENT;
+
+	remove_nexthop(net, nh, false, &nlinfo);
+
+	return 0;
+}
+
+static int nh_create_ipv4(struct net *net, struct nexthop *nh,
+			  struct nh_info *nhi, struct nh_config *cfg,
+			  struct netlink_ext_ack *extack)
+{
+	struct fib_nh *fib_nh = &nhi->fib_nh;
+	struct fib_config fib_cfg = {
+		.fc_oif   = cfg->nh_ifindex,
+		.fc_flow  = cfg->tclassid,
+		.fc_gw    = cfg->gw.ipv4,
+		.fc_flags = cfg->nh_flags,
+	};
+	int err;
+
+	err = fib_nh_init(net, fib_nh, &fib_cfg, 1, extack);
+	if (err)
+		goto out;
+
+	err = fib_check_nh(net, fib_nh, cfg->nh_table, cfg->nh_scope, extack);
+	if (!err) {
+		/* v4 code normally allows a nexthop device to have
+		 * carrier down; this code does not allow it
+		 */
+		if (fib_nh->nh_flags & RTNH_F_LINKDOWN) {
+			NL_SET_ERR_MSG(extack,
+				       "Carrier for nexthop device is down");
+			dev_put(fib_nh->nh_dev);
+			err = -ENETDOWN;
+			goto out;
+		}
+
+		nh->nh_flags = fib_nh->nh_flags;
+		fib_info_update_nh_saddr(net, fib_nh, fib_nh->nh_scope);
+	}
+
+	nhi->has_gw = !!fib_nh->nh_gw;
+out:
+	return err;
+}
+
+static int nh_create_ipv6(struct net *net,  struct nexthop *nh,
+			  struct nh_info *nhi, struct nh_config *cfg,
+			  struct netlink_ext_ack *extack)
+{
+	struct fib6_nh *fib6_nh = &nhi->fib6_nh;
+	struct fib6_config fib6_cfg = {
+		.fc_table = cfg->nh_table,
+		.fc_ifindex = cfg->nh_ifindex,
+		.fc_gateway = cfg->gw.ipv6,
+		.fc_flags = cfg->nh_flags,
+	};
+	int err;
+
+	if (!ipv6_addr_any(&cfg->gw.ipv6)) {
+		fib6_cfg.fc_flags |= RTF_GATEWAY;
+		nhi->has_gw = true;
+	}
+
+	err = ipv6_stub->fib6_nh_init(net, fib6_nh, &fib6_cfg, extack);
+	if (!err) {
+		if (fib6_cfg.fc_flags & RTF_REJECT) {
+			NL_SET_ERR_MSG(extack,
+				       "Nexthop can not use RTF_REJECT");
+			err = -EINVAL;
+			goto out;
+		}
+
+		if (fib6_nh->nh_flags & RTNH_F_LINKDOWN) {
+			NL_SET_ERR_MSG(extack,
+				       "Carrier for nexthop device is down");
+			err = -ENETDOWN;
+			goto out;
+		}
+
+		nh->nh_flags = fib6_nh->nh_flags;
+	}
+
+out:
+	if (err && fib6_nh->nh_dev)
+		dev_put(fib6_nh->nh_dev);
+	return err;
+}
+
+static int nh_create_unspec(struct net *net, struct nexthop *nh,
+			    struct nh_info *nhi, struct nh_config *cfg,
+			    struct netlink_ext_ack *extack)
+{
+	struct net_device *dev = cfg->dev;
+	int err = 0;
+
+	if (cfg->nh_blackhole) {
+		nhi->reject_nh = 1;
+	} else if (!dev) {
+		NL_SET_ERR_MSG(extack, "No device for nexthop");
+		err = -ENODEV;
+	} else {
+		/* leverage ipv4 infra for non-gw nexthop */
+		err = nh_create_ipv4(net, nh, nhi, cfg, extack);
+	}
+
+	return err;
+}
+
+static void nexthop_init_common(struct nexthop *nh)
+{
+	INIT_LIST_HEAD(&nh->fi_list);
+	INIT_LIST_HEAD(&nh->f6i_list);
+}
+
+static struct nexthop *nexthop_create(struct net *net, struct nh_config *cfg,
+				      struct netlink_ext_ack *extack)
+{
+	struct nh_info *nhi;
+	struct nexthop *nh;
+	int err;
+
+	nh = nexthop_alloc();
+	if (!nh)
+		return ERR_PTR(-ENOMEM);
+
+	nhi = kzalloc(sizeof(*nhi), GFP_KERNEL);
+	if (!nhi) {
+		kfree(nh);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	nh->nh_flags = cfg->nh_flags;
+	nexthop_init_common(nh);
+
+	nhi->nh_parent = nh;
+	nhi->family = cfg->nh_family;
+	nhi->net = net;
+	switch (cfg->nh_family) {
+	case AF_INET:
+		err = nh_create_ipv4(net, nh, nhi, cfg, extack);
+		break;
+	case AF_INET6:
+		err = nh_create_ipv6(net, nh, nhi, cfg, extack);
+		break;
+	default:
+		err = nh_create_unspec(net, nh, nhi, cfg, extack);
+	}
+
+	if (err) {
+		kfree(nhi);
+		kfree(nh);
+		return ERR_PTR(err);
+	}
+
+	/* add the entry to the device based hash */
+	if (!nhi->reject_nh)
+		nexthop_devhash_add(net, nhi);
+
+	rcu_assign_pointer(nh->nh_info, nhi);
+
+	return nh;
+}
+
+/* called with rtnl lock held */
+static struct nexthop *nexthop_add(struct net *net, struct nh_config *cfg,
+				   struct netlink_ext_ack *extack)
+{
+	struct nexthop *nh;
+	int err;
+
+	if (cfg->nlflags & NLM_F_REPLACE && !cfg->nh_id) {
+		NL_SET_ERR_MSG(extack, "Replace requires nexthop id");
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (!cfg->nh_id) {
+		cfg->nh_id = nh_find_unused_id(net);
+		if (!cfg->nh_id) {
+			NL_SET_ERR_MSG(extack, "No unused id.");
+			return ERR_PTR(-EINVAL);
+		}
+	}
+
+	nh = nexthop_create(net, cfg, extack);
+	if (IS_ERR(nh))
+		return nh;
+
+	refcount_set(&nh->refcnt, 1);
+	nh->id = cfg->nh_id;
+	nh->protocol = cfg->nh_protocol;
+
+	err = insert_nexthop(net, nh, cfg, extack);
+	if (err)
+		goto out_err;
+
+	return nh;
+out_err:
+	__remove_nexthop(net, nh, true, NULL);
+	nexthop_put(nh);
+
+	return ERR_PTR(err);
+}
+
+/* rtnl */
+static int rtm_new_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh,
+			   struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(skb->sk);
+	struct nh_config cfg;
+	struct nexthop *nh;
+	int err;
+
+	err = rtm_to_nh_config(net, skb, nlh, &cfg, extack);
+	if (!err) {
+		nh = nexthop_add(net, &cfg, extack);
+		if (IS_ERR(nh))
+			err = PTR_ERR(nh);
+	}
+
+	return err;
+}
+
+static bool nh_dump_filtered(struct nexthop *nh, int dev_idx,
+			     int master_idx, u8 family)
+{
+	const struct net_device *dev;
+	const struct nh_info *nhi;
+
+	if (dev_idx || master_idx || family)
+		return true;
+
+	nhi = rtnl_dereference(nh->nh_info);
+	if (family && nhi->family != family)
+		return true;
+
+	dev = nh_info_dev(nhi);
+	if (dev_idx && (!dev || dev->ifindex != dev_idx))
+		return true;
+
+	if (master_idx) {
+		struct net_device *master;
+
+		master = netdev_master_upper_dev_get((struct net_device *)dev);
+		if (!master || master->ifindex != master_idx)
+			return true;
+	}
+	return false;
+}
+
+/* rtnl */
+static int rtm_dump_nexthop(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	int dev_filter_idx = 0, master_idx = 0;
+	struct net *net = sock_net(skb->sk);
+	struct rb_root *root = &net->nexthop.root;
+	struct nlattr *tb[NHA_MAX + 1];
+	struct rb_node *node;
+	struct nhmsg *nhm;
+	int idx = 0;
+	int s_idx;
+	int err;
+
+	if (nlmsg_parse(cb->nlh, sizeof(*nhm), tb, NHA_MAX,
+			rtm_nh_policy, NULL) >= 0) {
+		if (tb[NHA_OIF])
+			dev_filter_idx = nla_get_u32(tb[NHA_OIF]);
+
+		if (tb[NHA_MASTER])
+			master_idx = nla_get_u32(tb[NHA_MASTER]);
+	}
+
+	nhm = nlmsg_data(cb->nlh);
+
+	s_idx = cb->args[0];
+	for (node = rb_first(root); node; node = rb_next(node)) {
+		struct nexthop *nh;
+
+		if (idx < s_idx)
+			goto cont;
+
+		nh = rb_entry(node, struct nexthop, rb_node);
+		if (nh_dump_filtered(nh, dev_filter_idx, master_idx,
+				     nhm->nh_family))
+			goto cont;
+
+		err = nh_fill_node(skb, nh, RTM_NEWNEXTHOP,
+				   NETLINK_CB(cb->skb).portid,
+				   cb->nlh->nlmsg_seq, NLM_F_MULTI);
+		if (err < 0) {
+			if (likely(skb->len))
+				goto out;
+
+			goto out_err;
+		}
+cont:
+		idx++;
+	}
+
+out:
+	err = skb->len;
+out_err:
+	cb->args[0] = idx;
+	cb->seq = net->nexthop.seq;
+	nl_dump_check_consistent(cb, nlmsg_hdr(skb));
+
+	return err;
+}
+
+/* rtnl */
+static int nh_netdev_event(struct notifier_block *this,
+			   unsigned long event, void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+
+	switch (event) {
+	case NETDEV_DOWN:
+	case NETDEV_UNREGISTER:
+		nexthop_flush_dev(dev);
+		break;
+	case NETDEV_CHANGE:
+		if (!(dev_get_flags(dev) & (IFF_RUNNING | IFF_LOWER_UP)))
+			nexthop_flush_dev(dev);
+		break;
+	}
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block nh_netdev_notifier = {
+	.notifier_call = nh_netdev_event,
+};
+
+static void __net_exit nexthop_net_exit(struct net *net)
+{
+	rtnl_lock();
+	flush_all_nexthops(net);
+	rtnl_unlock();
+	kfree(net->nexthop.devhash);
+}
+
+static int __net_init nexthop_net_init(struct net *net)
+{
+	size_t sz = sizeof(struct hlist_head) * NH_DEV_HASHSIZE;
+
+	net->nexthop.root = RB_ROOT;
+	net->nexthop.devhash = kzalloc(sz, GFP_KERNEL);
+	if (!net->nexthop.devhash)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static struct pernet_operations nexthop_net_ops = {
+	.init = nexthop_net_init,
+	.exit = nexthop_net_exit,
+};
+
+static int __init nexthop_init(void)
+{
+	register_pernet_subsys(&nexthop_net_ops);
+
+	register_netdevice_notifier(&nh_netdev_notifier);
+
+	rtnl_register(PF_UNSPEC, RTM_NEWNEXTHOP, rtm_new_nexthop, NULL, 0);
+	rtnl_register(PF_UNSPEC, RTM_DELNEXTHOP, rtm_del_nexthop, NULL, 0);
+	rtnl_register(PF_UNSPEC, RTM_GETNEXTHOP, rtm_get_nexthop,
+		      rtm_dump_nexthop, 0);
+
+	rtnl_register(PF_INET, RTM_NEWNEXTHOP, rtm_new_nexthop, NULL, 0);
+	rtnl_register(PF_INET, RTM_GETNEXTHOP, NULL, rtm_dump_nexthop, 0);
+
+	rtnl_register(PF_INET6, RTM_NEWNEXTHOP, rtm_new_nexthop, NULL, 0);
+	rtnl_register(PF_INET6, RTM_GETNEXTHOP, NULL, rtm_dump_nexthop, 0);
+
+	return 0;
+}
+subsys_initcall(nexthop_init);
diff --git a/security/selinux/nlmsgtab.c b/security/selinux/nlmsgtab.c
index 74b951f55608..7a852d5af14e 100644
--- a/security/selinux/nlmsgtab.c
+++ b/security/selinux/nlmsgtab.c
@@ -80,6 +80,9 @@ static const struct nlmsg_perm nlmsg_route_perms[] =
 	{ RTM_NEWSTATS,		NETLINK_ROUTE_SOCKET__NLMSG_READ },
 	{ RTM_GETSTATS,		NETLINK_ROUTE_SOCKET__NLMSG_READ  },
 	{ RTM_NEWCACHEREPORT,	NETLINK_ROUTE_SOCKET__NLMSG_READ },
+	{ RTM_NEWNEXTHOP,	NETLINK_ROUTE_SOCKET__NLMSG_WRITE },
+	{ RTM_DELNEXTHOP,	NETLINK_ROUTE_SOCKET__NLMSG_WRITE },
+	{ RTM_GETNEXTHOP,	NETLINK_ROUTE_SOCKET__NLMSG_READ  },
 };
 
 static const struct nlmsg_perm nlmsg_tcpdiag_perms[] =
@@ -159,7 +162,7 @@ int selinux_nlmsg_lookup(u16 sclass, u16 nlmsg_type, u32 *perm)
 	switch (sclass) {
 	case SECCLASS_NETLINK_ROUTE_SOCKET:
 		/* RTM_MAX always point to RTM_SETxxxx, ie RTM_NEWxxx + 3 */
-		BUILD_BUG_ON(RTM_MAX != (RTM_NEWCHAIN + 3));
+		BUILD_BUG_ON(RTM_MAX != (RTM_NEWNEXTHOP + 3));
 		err = nlmsg_perm(nlmsg_type, perm, nlmsg_route_perms,
 				 sizeof(nlmsg_route_perms));
 		break;
-- 
2.11.0