Adding upstream version 4.19.249.upstream/4.19.249

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

1 files changed, 1432 insertions, 0 deletions

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
new file mode 100644
index 000000000..1885a2fba
--- /dev/null
+++ b/net/ipv4/fib_frontend.c
@@ -0,0 +1,1432 @@
+/*
+ * INET		An implementation of the TCP/IP protocol suite for the LINUX
+ *		operating system.  INET is implemented using the  BSD Socket
+ *		interface as the means of communication with the user level.
+ *
+ *		IPv4 Forwarding Information Base: FIB frontend.
+ *
+ * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
+ *
+ *		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.
+ */
+
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/bitops.h>
+#include <linux/capability.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/string.h>
+#include <linux/socket.h>
+#include <linux/sockios.h>
+#include <linux/errno.h>
+#include <linux/in.h>
+#include <linux/inet.h>
+#include <linux/inetdevice.h>
+#include <linux/netdevice.h>
+#include <linux/if_addr.h>
+#include <linux/if_arp.h>
+#include <linux/skbuff.h>
+#include <linux/cache.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+
+#include <net/ip.h>
+#include <net/protocol.h>
+#include <net/route.h>
+#include <net/tcp.h>
+#include <net/sock.h>
+#include <net/arp.h>
+#include <net/ip_fib.h>
+#include <net/rtnetlink.h>
+#include <net/xfrm.h>
+#include <net/l3mdev.h>
+#include <net/lwtunnel.h>
+#include <trace/events/fib.h>
+
+#ifndef CONFIG_IP_MULTIPLE_TABLES
+
+static int __net_init fib4_rules_init(struct net *net)
+{
+	struct fib_table *local_table, *main_table;
+
+	main_table  = fib_trie_table(RT_TABLE_MAIN, NULL);
+	if (!main_table)
+		return -ENOMEM;
+
+	local_table = fib_trie_table(RT_TABLE_LOCAL, main_table);
+	if (!local_table)
+		goto fail;
+
+	hlist_add_head_rcu(&local_table->tb_hlist,
+				&net->ipv4.fib_table_hash[TABLE_LOCAL_INDEX]);
+	hlist_add_head_rcu(&main_table->tb_hlist,
+				&net->ipv4.fib_table_hash[TABLE_MAIN_INDEX]);
+	return 0;
+
+fail:
+	fib_free_table(main_table);
+	return -ENOMEM;
+}
+
+static bool fib4_has_custom_rules(struct net *net)
+{
+	return false;
+}
+#else
+
+struct fib_table *fib_new_table(struct net *net, u32 id)
+{
+	struct fib_table *tb, *alias = NULL;
+	unsigned int h;
+
+	if (id == 0)
+		id = RT_TABLE_MAIN;
+	tb = fib_get_table(net, id);
+	if (tb)
+		return tb;
+
+	if (id == RT_TABLE_LOCAL && !net->ipv4.fib_has_custom_rules)
+		alias = fib_new_table(net, RT_TABLE_MAIN);
+
+	tb = fib_trie_table(id, alias);
+	if (!tb)
+		return NULL;
+
+	switch (id) {
+	case RT_TABLE_MAIN:
+		rcu_assign_pointer(net->ipv4.fib_main, tb);
+		break;
+	case RT_TABLE_DEFAULT:
+		rcu_assign_pointer(net->ipv4.fib_default, tb);
+		break;
+	default:
+		break;
+	}
+
+	h = id & (FIB_TABLE_HASHSZ - 1);
+	hlist_add_head_rcu(&tb->tb_hlist, &net->ipv4.fib_table_hash[h]);
+	return tb;
+}
+EXPORT_SYMBOL_GPL(fib_new_table);
+
+/* caller must hold either rtnl or rcu read lock */
+struct fib_table *fib_get_table(struct net *net, u32 id)
+{
+	struct fib_table *tb;
+	struct hlist_head *head;
+	unsigned int h;
+
+	if (id == 0)
+		id = RT_TABLE_MAIN;
+	h = id & (FIB_TABLE_HASHSZ - 1);
+
+	head = &net->ipv4.fib_table_hash[h];
+	hlist_for_each_entry_rcu(tb, head, tb_hlist) {
+		if (tb->tb_id == id)
+			return tb;
+	}
+	return NULL;
+}
+
+static bool fib4_has_custom_rules(struct net *net)
+{
+	return net->ipv4.fib_has_custom_rules;
+}
+#endif /* CONFIG_IP_MULTIPLE_TABLES */
+
+static void fib_replace_table(struct net *net, struct fib_table *old,
+			      struct fib_table *new)
+{
+#ifdef CONFIG_IP_MULTIPLE_TABLES
+	switch (new->tb_id) {
+	case RT_TABLE_MAIN:
+		rcu_assign_pointer(net->ipv4.fib_main, new);
+		break;
+	case RT_TABLE_DEFAULT:
+		rcu_assign_pointer(net->ipv4.fib_default, new);
+		break;
+	default:
+		break;
+	}
+
+#endif
+	/* replace the old table in the hlist */
+	hlist_replace_rcu(&old->tb_hlist, &new->tb_hlist);
+}
+
+int fib_unmerge(struct net *net)
+{
+	struct fib_table *old, *new, *main_table;
+
+	/* attempt to fetch local table if it has been allocated */
+	old = fib_get_table(net, RT_TABLE_LOCAL);
+	if (!old)
+		return 0;
+
+	new = fib_trie_unmerge(old);
+	if (!new)
+		return -ENOMEM;
+
+	/* table is already unmerged */
+	if (new == old)
+		return 0;
+
+	/* replace merged table with clean table */
+	fib_replace_table(net, old, new);
+	fib_free_table(old);
+
+	/* attempt to fetch main table if it has been allocated */
+	main_table = fib_get_table(net, RT_TABLE_MAIN);
+	if (!main_table)
+		return 0;
+
+	/* flush local entries from main table */
+	fib_table_flush_external(main_table);
+
+	return 0;
+}
+
+static void fib_flush(struct net *net)
+{
+	int flushed = 0;
+	unsigned int h;
+
+	for (h = 0; h < FIB_TABLE_HASHSZ; h++) {
+		struct hlist_head *head = &net->ipv4.fib_table_hash[h];
+		struct hlist_node *tmp;
+		struct fib_table *tb;
+
+		hlist_for_each_entry_safe(tb, tmp, head, tb_hlist)
+			flushed += fib_table_flush(net, tb, false);
+	}
+
+	if (flushed)
+		rt_cache_flush(net);
+}
+
+/*
+ * Find address type as if only "dev" was present in the system. If
+ * on_dev is NULL then all interfaces are taken into consideration.
+ */
+static inline unsigned int __inet_dev_addr_type(struct net *net,
+						const struct net_device *dev,
+						__be32 addr, u32 tb_id)
+{
+	struct flowi4		fl4 = { .daddr = addr };
+	struct fib_result	res;
+	unsigned int ret = RTN_BROADCAST;
+	struct fib_table *table;
+
+	if (ipv4_is_zeronet(addr) || ipv4_is_lbcast(addr))
+		return RTN_BROADCAST;
+	if (ipv4_is_multicast(addr))
+		return RTN_MULTICAST;
+
+	rcu_read_lock();
+
+	table = fib_get_table(net, tb_id);
+	if (table) {
+		ret = RTN_UNICAST;
+		if (!fib_table_lookup(table, &fl4, &res, FIB_LOOKUP_NOREF)) {
+			if (!dev || dev == res.fi->fib_dev)
+				ret = res.type;
+		}
+	}
+
+	rcu_read_unlock();
+	return ret;
+}
+
+unsigned int inet_addr_type_table(struct net *net, __be32 addr, u32 tb_id)
+{
+	return __inet_dev_addr_type(net, NULL, addr, tb_id);
+}
+EXPORT_SYMBOL(inet_addr_type_table);
+
+unsigned int inet_addr_type(struct net *net, __be32 addr)
+{
+	return __inet_dev_addr_type(net, NULL, addr, RT_TABLE_LOCAL);
+}
+EXPORT_SYMBOL(inet_addr_type);
+
+unsigned int inet_dev_addr_type(struct net *net, const struct net_device *dev,
+				__be32 addr)
+{
+	u32 rt_table = l3mdev_fib_table(dev) ? : RT_TABLE_LOCAL;
+
+	return __inet_dev_addr_type(net, dev, addr, rt_table);
+}
+EXPORT_SYMBOL(inet_dev_addr_type);
+
+/* inet_addr_type with dev == NULL but using the table from a dev
+ * if one is associated
+ */
+unsigned int inet_addr_type_dev_table(struct net *net,
+				      const struct net_device *dev,
+				      __be32 addr)
+{
+	u32 rt_table = l3mdev_fib_table(dev) ? : RT_TABLE_LOCAL;
+
+	return __inet_dev_addr_type(net, NULL, addr, rt_table);
+}
+EXPORT_SYMBOL(inet_addr_type_dev_table);
+
+__be32 fib_compute_spec_dst(struct sk_buff *skb)
+{
+	struct net_device *dev = skb->dev;
+	struct in_device *in_dev;
+	struct fib_result res;
+	struct rtable *rt;
+	struct net *net;
+	int scope;
+
+	rt = skb_rtable(skb);
+	if ((rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST | RTCF_LOCAL)) ==
+	    RTCF_LOCAL)
+		return ip_hdr(skb)->daddr;
+
+	in_dev = __in_dev_get_rcu(dev);
+
+	net = dev_net(dev);
+
+	scope = RT_SCOPE_UNIVERSE;
+	if (!ipv4_is_zeronet(ip_hdr(skb)->saddr)) {
+		bool vmark = in_dev && IN_DEV_SRC_VMARK(in_dev);
+		struct flowi4 fl4 = {
+			.flowi4_iif = LOOPBACK_IFINDEX,
+			.flowi4_oif = l3mdev_master_ifindex_rcu(dev),
+			.daddr = ip_hdr(skb)->saddr,
+			.flowi4_tos = ip_hdr(skb)->tos & IPTOS_RT_MASK,
+			.flowi4_scope = scope,
+			.flowi4_mark = vmark ? skb->mark : 0,
+		};
+		if (!fib_lookup(net, &fl4, &res, 0))
+			return FIB_RES_PREFSRC(net, res);
+	} else {
+		scope = RT_SCOPE_LINK;
+	}
+
+	return inet_select_addr(dev, ip_hdr(skb)->saddr, scope);
+}
+
+/* Given (packet source, input interface) and optional (dst, oif, tos):
+ * - (main) check, that source is valid i.e. not broadcast or our local
+ *   address.
+ * - figure out what "logical" interface this packet arrived
+ *   and calculate "specific destination" address.
+ * - check, that packet arrived from expected physical interface.
+ * called with rcu_read_lock()
+ */
+static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
+				 u8 tos, int oif, struct net_device *dev,
+				 int rpf, struct in_device *idev, u32 *itag)
+{
+	struct net *net = dev_net(dev);
+	struct flow_keys flkeys;
+	int ret, no_addr;
+	struct fib_result res;
+	struct flowi4 fl4;
+	bool dev_match;
+
+	fl4.flowi4_oif = 0;
+	fl4.flowi4_iif = l3mdev_master_ifindex_rcu(dev);
+	if (!fl4.flowi4_iif)
+		fl4.flowi4_iif = oif ? : LOOPBACK_IFINDEX;
+	fl4.daddr = src;
+	fl4.saddr = dst;
+	fl4.flowi4_tos = tos;
+	fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
+	fl4.flowi4_tun_key.tun_id = 0;
+	fl4.flowi4_flags = 0;
+	fl4.flowi4_uid = sock_net_uid(net, NULL);
+
+	no_addr = idev->ifa_list == NULL;
+
+	fl4.flowi4_mark = IN_DEV_SRC_VMARK(idev) ? skb->mark : 0;
+	if (!fib4_rules_early_flow_dissect(net, skb, &fl4, &flkeys)) {
+		fl4.flowi4_proto = 0;
+		fl4.fl4_sport = 0;
+		fl4.fl4_dport = 0;
+	} else {
+		swap(fl4.fl4_sport, fl4.fl4_dport);
+	}
+
+	if (fib_lookup(net, &fl4, &res, 0))
+		goto last_resort;
+	if (res.type != RTN_UNICAST &&
+	    (res.type != RTN_LOCAL || !IN_DEV_ACCEPT_LOCAL(idev)))
+		goto e_inval;
+	fib_combine_itag(itag, &res);
+	dev_match = false;
+
+#ifdef CONFIG_IP_ROUTE_MULTIPATH
+	for (ret = 0; ret < res.fi->fib_nhs; ret++) {
+		struct fib_nh *nh = &res.fi->fib_nh[ret];
+
+		if (nh->nh_dev == dev) {
+			dev_match = true;
+			break;
+		} else if (l3mdev_master_ifindex_rcu(nh->nh_dev) == dev->ifindex) {
+			dev_match = true;
+			break;
+		}
+	}
+#else
+	if (FIB_RES_DEV(res) == dev)
+		dev_match = true;
+#endif
+	if (dev_match) {
+		ret = FIB_RES_NH(res).nh_scope >= RT_SCOPE_HOST;
+		return ret;
+	}
+	if (no_addr)
+		goto last_resort;
+	if (rpf == 1)
+		goto e_rpf;
+	fl4.flowi4_oif = dev->ifindex;
+
+	ret = 0;
+	if (fib_lookup(net, &fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE) == 0) {
+		if (res.type == RTN_UNICAST)
+			ret = FIB_RES_NH(res).nh_scope >= RT_SCOPE_HOST;
+	}
+	return ret;
+
+last_resort:
+	if (rpf)
+		goto e_rpf;
+	*itag = 0;
+	return 0;
+
+e_inval:
+	return -EINVAL;
+e_rpf:
+	return -EXDEV;
+}
+
+/* Ignore rp_filter for packets protected by IPsec. */
+int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
+			u8 tos, int oif, struct net_device *dev,
+			struct in_device *idev, u32 *itag)
+{
+	int r = secpath_exists(skb) ? 0 : IN_DEV_RPFILTER(idev);
+	struct net *net = dev_net(dev);
+
+	if (!r && !fib_num_tclassid_users(net) &&
+	    (dev->ifindex != oif || !IN_DEV_TX_REDIRECTS(idev))) {
+		if (IN_DEV_ACCEPT_LOCAL(idev))
+			goto ok;
+		/* with custom local routes in place, checking local addresses
+		 * only will be too optimistic, with custom rules, checking
+		 * local addresses only can be too strict, e.g. due to vrf
+		 */
+		if (net->ipv4.fib_has_custom_local_routes ||
+		    fib4_has_custom_rules(net))
+			goto full_check;
+		if (inet_lookup_ifaddr_rcu(net, src))
+			return -EINVAL;
+
+ok:
+		*itag = 0;
+		return 0;
+	}
+
+full_check:
+	return __fib_validate_source(skb, src, dst, tos, oif, dev, r, idev, itag);
+}
+
+static inline __be32 sk_extract_addr(struct sockaddr *addr)
+{
+	return ((struct sockaddr_in *) addr)->sin_addr.s_addr;
+}
+
+static int put_rtax(struct nlattr *mx, int len, int type, u32 value)
+{
+	struct nlattr *nla;
+
+	nla = (struct nlattr *) ((char *) mx + len);
+	nla->nla_type = type;
+	nla->nla_len = nla_attr_size(4);
+	*(u32 *) nla_data(nla) = value;
+
+	return len + nla_total_size(4);
+}
+
+static int rtentry_to_fib_config(struct net *net, int cmd, struct rtentry *rt,
+				 struct fib_config *cfg)
+{
+	__be32 addr;
+	int plen;
+
+	memset(cfg, 0, sizeof(*cfg));
+	cfg->fc_nlinfo.nl_net = net;
+
+	if (rt->rt_dst.sa_family != AF_INET)
+		return -EAFNOSUPPORT;
+
+	/*
+	 * Check mask for validity:
+	 * a) it must be contiguous.
+	 * b) destination must have all host bits clear.
+	 * c) if application forgot to set correct family (AF_INET),
+	 *    reject request unless it is absolutely clear i.e.
+	 *    both family and mask are zero.
+	 */
+	plen = 32;
+	addr = sk_extract_addr(&rt->rt_dst);
+	if (!(rt->rt_flags & RTF_HOST)) {
+		__be32 mask = sk_extract_addr(&rt->rt_genmask);
+
+		if (rt->rt_genmask.sa_family != AF_INET) {
+			if (mask || rt->rt_genmask.sa_family)
+				return -EAFNOSUPPORT;
+		}
+
+		if (bad_mask(mask, addr))
+			return -EINVAL;
+
+		plen = inet_mask_len(mask);
+	}
+
+	cfg->fc_dst_len = plen;
+	cfg->fc_dst = addr;
+
+	if (cmd != SIOCDELRT) {
+		cfg->fc_nlflags = NLM_F_CREATE;
+		cfg->fc_protocol = RTPROT_BOOT;
+	}
+
+	if (rt->rt_metric)
+		cfg->fc_priority = rt->rt_metric - 1;
+
+	if (rt->rt_flags & RTF_REJECT) {
+		cfg->fc_scope = RT_SCOPE_HOST;
+		cfg->fc_type = RTN_UNREACHABLE;
+		return 0;
+	}
+
+	cfg->fc_scope = RT_SCOPE_NOWHERE;
+	cfg->fc_type = RTN_UNICAST;
+
+	if (rt->rt_dev) {
+		char *colon;
+		struct net_device *dev;
+		char devname[IFNAMSIZ];
+
+		if (copy_from_user(devname, rt->rt_dev, IFNAMSIZ-1))
+			return -EFAULT;
+
+		devname[IFNAMSIZ-1] = 0;
+		colon = strchr(devname, ':');
+		if (colon)
+			*colon = 0;
+		dev = __dev_get_by_name(net, devname);
+		if (!dev)
+			return -ENODEV;
+		cfg->fc_oif = dev->ifindex;
+		cfg->fc_table = l3mdev_fib_table(dev);
+		if (colon) {
+			struct in_ifaddr *ifa;
+			struct in_device *in_dev = __in_dev_get_rtnl(dev);
+			if (!in_dev)
+				return -ENODEV;
+			*colon = ':';
+			for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next)
+				if (strcmp(ifa->ifa_label, devname) == 0)
+					break;
+			if (!ifa)
+				return -ENODEV;
+			cfg->fc_prefsrc = ifa->ifa_local;
+		}
+	}
+
+	addr = sk_extract_addr(&rt->rt_gateway);
+	if (rt->rt_gateway.sa_family == AF_INET && addr) {
+		unsigned int addr_type;
+
+		cfg->fc_gw = addr;
+		addr_type = inet_addr_type_table(net, addr, cfg->fc_table);
+		if (rt->rt_flags & RTF_GATEWAY &&
+		    addr_type == RTN_UNICAST)
+			cfg->fc_scope = RT_SCOPE_UNIVERSE;
+	}
+
+	if (cmd == SIOCDELRT)
+		return 0;
+
+	if (rt->rt_flags & RTF_GATEWAY && !cfg->fc_gw)
+		return -EINVAL;
+
+	if (cfg->fc_scope == RT_SCOPE_NOWHERE)
+		cfg->fc_scope = RT_SCOPE_LINK;
+
+	if (rt->rt_flags & (RTF_MTU | RTF_WINDOW | RTF_IRTT)) {
+		struct nlattr *mx;
+		int len = 0;
+
+		mx = kcalloc(3, nla_total_size(4), GFP_KERNEL);
+		if (!mx)
+			return -ENOMEM;
+
+		if (rt->rt_flags & RTF_MTU)
+			len = put_rtax(mx, len, RTAX_ADVMSS, rt->rt_mtu - 40);
+
+		if (rt->rt_flags & RTF_WINDOW)
+			len = put_rtax(mx, len, RTAX_WINDOW, rt->rt_window);
+
+		if (rt->rt_flags & RTF_IRTT)
+			len = put_rtax(mx, len, RTAX_RTT, rt->rt_irtt << 3);
+
+		cfg->fc_mx = mx;
+		cfg->fc_mx_len = len;
+	}
+
+	return 0;
+}
+
+/*
+ * Handle IP routing ioctl calls.
+ * These are used to manipulate the routing tables
+ */
+int ip_rt_ioctl(struct net *net, unsigned int cmd, struct rtentry *rt)
+{
+	struct fib_config cfg;
+	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;
+
+		rtnl_lock();
+		err = rtentry_to_fib_config(net, cmd, rt, &cfg);
+		if (err == 0) {
+			struct fib_table *tb;
+
+			if (cmd == SIOCDELRT) {
+				tb = fib_get_table(net, cfg.fc_table);
+				if (tb)
+					err = fib_table_delete(net, tb, &cfg,
+							       NULL);
+				else
+					err = -ESRCH;
+			} else {
+				tb = fib_new_table(net, cfg.fc_table);
+				if (tb)
+					err = fib_table_insert(net, tb,
+							       &cfg, NULL);
+				else
+					err = -ENOBUFS;
+			}
+
+			/* allocated by rtentry_to_fib_config() */
+			kfree(cfg.fc_mx);
+		}
+		rtnl_unlock();
+		return err;
+	}
+	return -EINVAL;
+}
+
+const struct nla_policy rtm_ipv4_policy[RTA_MAX + 1] = {
+	[RTA_DST]		= { .type = NLA_U32 },
+	[RTA_SRC]		= { .type = NLA_U32 },
+	[RTA_IIF]		= { .type = NLA_U32 },
+	[RTA_OIF]		= { .type = NLA_U32 },
+	[RTA_GATEWAY]		= { .type = NLA_U32 },
+	[RTA_PRIORITY]		= { .type = NLA_U32 },
+	[RTA_PREFSRC]		= { .type = NLA_U32 },
+	[RTA_METRICS]		= { .type = NLA_NESTED },
+	[RTA_MULTIPATH]		= { .len = sizeof(struct rtnexthop) },
+	[RTA_FLOW]		= { .type = NLA_U32 },
+	[RTA_ENCAP_TYPE]	= { .type = NLA_U16 },
+	[RTA_ENCAP]		= { .type = NLA_NESTED },
+	[RTA_UID]		= { .type = NLA_U32 },
+	[RTA_MARK]		= { .type = NLA_U32 },
+	[RTA_TABLE]		= { .type = NLA_U32 },
+	[RTA_IP_PROTO]		= { .type = NLA_U8 },
+	[RTA_SPORT]		= { .type = NLA_U16 },
+	[RTA_DPORT]		= { .type = NLA_U16 },
+};
+
+static int rtm_to_fib_config(struct net *net, struct sk_buff *skb,
+			     struct nlmsghdr *nlh, struct fib_config *cfg,
+			     struct netlink_ext_ack *extack)
+{
+	struct nlattr *attr;
+	int err, remaining;
+	struct rtmsg *rtm;
+
+	err = nlmsg_validate(nlh, sizeof(*rtm), RTA_MAX, rtm_ipv4_policy,
+			     extack);
+	if (err < 0)
+		goto errout;
+
+	memset(cfg, 0, sizeof(*cfg));
+
+	rtm = nlmsg_data(nlh);
+	cfg->fc_dst_len = rtm->rtm_dst_len;
+	cfg->fc_tos = rtm->rtm_tos;
+	cfg->fc_table = rtm->rtm_table;
+	cfg->fc_protocol = rtm->rtm_protocol;
+	cfg->fc_scope = rtm->rtm_scope;
+	cfg->fc_type = rtm->rtm_type;
+	cfg->fc_flags = rtm->rtm_flags;
+	cfg->fc_nlflags = nlh->nlmsg_flags;
+
+	cfg->fc_nlinfo.portid = NETLINK_CB(skb).portid;
+	cfg->fc_nlinfo.nlh = nlh;
+	cfg->fc_nlinfo.nl_net = net;
+
+	if (cfg->fc_type > RTN_MAX) {
+		NL_SET_ERR_MSG(extack, "Invalid route type");
+		err = -EINVAL;
+		goto errout;
+	}
+
+	nlmsg_for_each_attr(attr, nlh, sizeof(struct rtmsg), remaining) {
+		switch (nla_type(attr)) {
+		case RTA_DST:
+			cfg->fc_dst = nla_get_be32(attr);
+			break;
+		case RTA_OIF:
+			cfg->fc_oif = nla_get_u32(attr);
+			break;
+		case RTA_GATEWAY:
+			cfg->fc_gw = nla_get_be32(attr);
+			break;
+		case RTA_VIA:
+			NL_SET_ERR_MSG(extack, "IPv4 does not support RTA_VIA attribute");
+			err = -EINVAL;
+			goto errout;
+		case RTA_PRIORITY:
+			cfg->fc_priority = nla_get_u32(attr);
+			break;
+		case RTA_PREFSRC:
+			cfg->fc_prefsrc = nla_get_be32(attr);
+			break;
+		case RTA_METRICS:
+			cfg->fc_mx = nla_data(attr);
+			cfg->fc_mx_len = nla_len(attr);
+			break;
+		case RTA_MULTIPATH:
+			err = lwtunnel_valid_encap_type_attr(nla_data(attr),
+							     nla_len(attr),
+							     extack);
+			if (err < 0)
+				goto errout;
+			cfg->fc_mp = nla_data(attr);
+			cfg->fc_mp_len = nla_len(attr);
+			break;
+		case RTA_FLOW:
+			cfg->fc_flow = nla_get_u32(attr);
+			break;
+		case RTA_TABLE:
+			cfg->fc_table = nla_get_u32(attr);
+			break;
+		case RTA_ENCAP:
+			cfg->fc_encap = attr;
+			break;
+		case RTA_ENCAP_TYPE:
+			cfg->fc_encap_type = nla_get_u16(attr);
+			err = lwtunnel_valid_encap_type(cfg->fc_encap_type,
+							extack);
+			if (err < 0)
+				goto errout;
+			break;
+		}
+	}
+
+	return 0;
+errout:
+	return err;
+}
+
+static int inet_rtm_delroute(struct sk_buff *skb, struct nlmsghdr *nlh,
+			     struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(skb->sk);
+	struct fib_config cfg;
+	struct fib_table *tb;
+	int err;
+
+	err = rtm_to_fib_config(net, skb, nlh, &cfg, extack);
+	if (err < 0)
+		goto errout;
+
+	tb = fib_get_table(net, cfg.fc_table);
+	if (!tb) {
+		NL_SET_ERR_MSG(extack, "FIB table does not exist");
+		err = -ESRCH;
+		goto errout;
+	}
+
+	err = fib_table_delete(net, tb, &cfg, extack);
+errout:
+	return err;
+}
+
+static int inet_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh,
+			     struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(skb->sk);
+	struct fib_config cfg;
+	struct fib_table *tb;
+	int err;
+
+	err = rtm_to_fib_config(net, skb, nlh, &cfg, extack);
+	if (err < 0)
+		goto errout;
+
+	tb = fib_new_table(net, cfg.fc_table);
+	if (!tb) {
+		err = -ENOBUFS;
+		goto errout;
+	}
+
+	err = fib_table_insert(net, tb, &cfg, extack);
+	if (!err && cfg.fc_type == RTN_LOCAL)
+		net->ipv4.fib_has_custom_local_routes = true;
+errout:
+	return err;
+}
+
+static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	struct net *net = sock_net(skb->sk);
+	unsigned int h, s_h;
+	unsigned int e = 0, s_e;
+	struct fib_table *tb;
+	struct hlist_head *head;
+	int dumped = 0, err;
+
+	if (nlmsg_len(cb->nlh) >= sizeof(struct rtmsg) &&
+	    ((struct rtmsg *) nlmsg_data(cb->nlh))->rtm_flags & RTM_F_CLONED)
+		return skb->len;
+
+	s_h = cb->args[0];
+	s_e = cb->args[1];
+
+	rcu_read_lock();
+
+	for (h = s_h; h < FIB_TABLE_HASHSZ; h++, s_e = 0) {
+		e = 0;
+		head = &net->ipv4.fib_table_hash[h];
+		hlist_for_each_entry_rcu(tb, head, tb_hlist) {
+			if (e < s_e)
+				goto next;
+			if (dumped)
+				memset(&cb->args[2], 0, sizeof(cb->args) -
+						 2 * sizeof(cb->args[0]));
+			err = fib_table_dump(tb, skb, cb);
+			if (err < 0) {
+				if (likely(skb->len))
+					goto out;
+
+				goto out_err;
+			}
+			dumped = 1;
+next:
+			e++;
+		}
+	}
+out:
+	err = skb->len;
+out_err:
+	rcu_read_unlock();
+
+	cb->args[1] = e;
+	cb->args[0] = h;
+
+	return err;
+}
+
+/* Prepare and feed intra-kernel routing request.
+ * Really, it should be netlink message, but :-( netlink
+ * can be not configured, so that we feed it directly
+ * to fib engine. It is legal, because all events occur
+ * only when netlink is already locked.
+ */
+static void fib_magic(int cmd, int type, __be32 dst, int dst_len,
+		      struct in_ifaddr *ifa, u32 rt_priority)
+{
+	struct net *net = dev_net(ifa->ifa_dev->dev);
+	u32 tb_id = l3mdev_fib_table(ifa->ifa_dev->dev);
+	struct fib_table *tb;
+	struct fib_config cfg = {
+		.fc_protocol = RTPROT_KERNEL,
+		.fc_type = type,
+		.fc_dst = dst,
+		.fc_dst_len = dst_len,
+		.fc_priority = rt_priority,
+		.fc_prefsrc = ifa->ifa_local,
+		.fc_oif = ifa->ifa_dev->dev->ifindex,
+		.fc_nlflags = NLM_F_CREATE | NLM_F_APPEND,
+		.fc_nlinfo = {
+			.nl_net = net,
+		},
+	};
+
+	if (!tb_id)
+		tb_id = (type == RTN_UNICAST) ? RT_TABLE_MAIN : RT_TABLE_LOCAL;
+
+	tb = fib_new_table(net, tb_id);
+	if (!tb)
+		return;
+
+	cfg.fc_table = tb->tb_id;
+
+	if (type != RTN_LOCAL)
+		cfg.fc_scope = RT_SCOPE_LINK;
+	else
+		cfg.fc_scope = RT_SCOPE_HOST;
+
+	if (cmd == RTM_NEWROUTE)
+		fib_table_insert(net, tb, &cfg, NULL);
+	else
+		fib_table_delete(net, tb, &cfg, NULL);
+}
+
+void fib_add_ifaddr(struct in_ifaddr *ifa)
+{
+	struct in_device *in_dev = ifa->ifa_dev;
+	struct net_device *dev = in_dev->dev;
+	struct in_ifaddr *prim = ifa;
+	__be32 mask = ifa->ifa_mask;
+	__be32 addr = ifa->ifa_local;
+	__be32 prefix = ifa->ifa_address & mask;
+
+	if (ifa->ifa_flags & IFA_F_SECONDARY) {
+		prim = inet_ifa_byprefix(in_dev, prefix, mask);
+		if (!prim) {
+			pr_warn("%s: bug: prim == NULL\n", __func__);
+			return;
+		}
+	}
+
+	fib_magic(RTM_NEWROUTE, RTN_LOCAL, addr, 32, prim, 0);
+
+	if (!(dev->flags & IFF_UP))
+		return;
+
+	/* Add broadcast address, if it is explicitly assigned. */
+	if (ifa->ifa_broadcast && ifa->ifa_broadcast != htonl(0xFFFFFFFF)) {
+		fib_magic(RTM_NEWROUTE, RTN_BROADCAST, ifa->ifa_broadcast, 32,
+			  prim, 0);
+		arp_invalidate(dev, ifa->ifa_broadcast, false);
+	}
+
+	if (!ipv4_is_zeronet(prefix) && !(ifa->ifa_flags & IFA_F_SECONDARY) &&
+	    (prefix != addr || ifa->ifa_prefixlen < 32)) {
+		if (!(ifa->ifa_flags & IFA_F_NOPREFIXROUTE))
+			fib_magic(RTM_NEWROUTE,
+				  dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,
+				  prefix, ifa->ifa_prefixlen, prim,
+				  ifa->ifa_rt_priority);
+
+		/* Add network specific broadcasts, when it takes a sense */
+		if (ifa->ifa_prefixlen < 31) {
+			fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix, 32,
+				  prim, 0);
+			fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix | ~mask,
+				  32, prim, 0);
+			arp_invalidate(dev, prefix | ~mask, false);
+		}
+	}
+}
+
+void fib_modify_prefix_metric(struct in_ifaddr *ifa, u32 new_metric)
+{
+	__be32 prefix = ifa->ifa_address & ifa->ifa_mask;
+	struct in_device *in_dev = ifa->ifa_dev;
+	struct net_device *dev = in_dev->dev;
+
+	if (!(dev->flags & IFF_UP) ||
+	    ifa->ifa_flags & (IFA_F_SECONDARY | IFA_F_NOPREFIXROUTE) ||
+	    ipv4_is_zeronet(prefix) ||
+	    (prefix == ifa->ifa_local && ifa->ifa_prefixlen == 32))
+		return;
+
+	/* add the new */
+	fib_magic(RTM_NEWROUTE,
+		  dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,
+		  prefix, ifa->ifa_prefixlen, ifa, new_metric);
+
+	/* delete the old */
+	fib_magic(RTM_DELROUTE,
+		  dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,
+		  prefix, ifa->ifa_prefixlen, ifa, ifa->ifa_rt_priority);
+}
+
+/* Delete primary or secondary address.
+ * Optionally, on secondary address promotion consider the addresses
+ * from subnet iprim as deleted, even if they are in device list.
+ * In this case the secondary ifa can be in device list.
+ */
+void fib_del_ifaddr(struct in_ifaddr *ifa, struct in_ifaddr *iprim)
+{
+	struct in_device *in_dev = ifa->ifa_dev;
+	struct net_device *dev = in_dev->dev;
+	struct in_ifaddr *ifa1;
+	struct in_ifaddr *prim = ifa, *prim1 = NULL;
+	__be32 brd = ifa->ifa_address | ~ifa->ifa_mask;
+	__be32 any = ifa->ifa_address & ifa->ifa_mask;
+#define LOCAL_OK	1
+#define BRD_OK		2
+#define BRD0_OK		4
+#define BRD1_OK		8
+	unsigned int ok = 0;
+	int subnet = 0;		/* Primary network */
+	int gone = 1;		/* Address is missing */
+	int same_prefsrc = 0;	/* Another primary with same IP */
+
+	if (ifa->ifa_flags & IFA_F_SECONDARY) {
+		prim = inet_ifa_byprefix(in_dev, any, ifa->ifa_mask);
+		if (!prim) {
+			/* if the device has been deleted, we don't perform
+			 * address promotion
+			 */
+			if (!in_dev->dead)
+				pr_warn("%s: bug: prim == NULL\n", __func__);
+			return;
+		}
+		if (iprim && iprim != prim) {
+			pr_warn("%s: bug: iprim != prim\n", __func__);
+			return;
+		}
+	} else if (!ipv4_is_zeronet(any) &&
+		   (any != ifa->ifa_local || ifa->ifa_prefixlen < 32)) {
+		if (!(ifa->ifa_flags & IFA_F_NOPREFIXROUTE))
+			fib_magic(RTM_DELROUTE,
+				  dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,
+				  any, ifa->ifa_prefixlen, prim, 0);
+		subnet = 1;
+	}
+
+	if (in_dev->dead)
+		goto no_promotions;
+
+	/* Deletion is more complicated than add.
+	 * We should take care of not to delete too much :-)
+	 *
+	 * Scan address list to be sure that addresses are really gone.
+	 */
+
+	for (ifa1 = in_dev->ifa_list; ifa1; ifa1 = ifa1->ifa_next) {
+		if (ifa1 == ifa) {
+			/* promotion, keep the IP */
+			gone = 0;
+			continue;
+		}
+		/* Ignore IFAs from our subnet */
+		if (iprim && ifa1->ifa_mask == iprim->ifa_mask &&
+		    inet_ifa_match(ifa1->ifa_address, iprim))
+			continue;
+
+		/* Ignore ifa1 if it uses different primary IP (prefsrc) */
+		if (ifa1->ifa_flags & IFA_F_SECONDARY) {
+			/* Another address from our subnet? */
+			if (ifa1->ifa_mask == prim->ifa_mask &&
+			    inet_ifa_match(ifa1->ifa_address, prim))
+				prim1 = prim;
+			else {
+				/* We reached the secondaries, so
+				 * same_prefsrc should be determined.
+				 */
+				if (!same_prefsrc)
+					continue;
+				/* Search new prim1 if ifa1 is not
+				 * using the current prim1
+				 */
+				if (!prim1 ||
+				    ifa1->ifa_mask != prim1->ifa_mask ||
+				    !inet_ifa_match(ifa1->ifa_address, prim1))
+					prim1 = inet_ifa_byprefix(in_dev,
+							ifa1->ifa_address,
+							ifa1->ifa_mask);
+				if (!prim1)
+					continue;
+				if (prim1->ifa_local != prim->ifa_local)
+					continue;
+			}
+		} else {
+			if (prim->ifa_local != ifa1->ifa_local)
+				continue;
+			prim1 = ifa1;
+			if (prim != prim1)
+				same_prefsrc = 1;
+		}
+		if (ifa->ifa_local == ifa1->ifa_local)
+			ok |= LOCAL_OK;
+		if (ifa->ifa_broadcast == ifa1->ifa_broadcast)
+			ok |= BRD_OK;
+		if (brd == ifa1->ifa_broadcast)
+			ok |= BRD1_OK;
+		if (any == ifa1->ifa_broadcast)
+			ok |= BRD0_OK;
+		/* primary has network specific broadcasts */
+		if (prim1 == ifa1 && ifa1->ifa_prefixlen < 31) {
+			__be32 brd1 = ifa1->ifa_address | ~ifa1->ifa_mask;
+			__be32 any1 = ifa1->ifa_address & ifa1->ifa_mask;
+
+			if (!ipv4_is_zeronet(any1)) {
+				if (ifa->ifa_broadcast == brd1 ||
+				    ifa->ifa_broadcast == any1)
+					ok |= BRD_OK;
+				if (brd == brd1 || brd == any1)
+					ok |= BRD1_OK;
+				if (any == brd1 || any == any1)
+					ok |= BRD0_OK;
+			}
+		}
+	}
+
+no_promotions:
+	if (!(ok & BRD_OK))
+		fib_magic(RTM_DELROUTE, RTN_BROADCAST, ifa->ifa_broadcast, 32,
+			  prim, 0);
+	if (subnet && ifa->ifa_prefixlen < 31) {
+		if (!(ok & BRD1_OK))
+			fib_magic(RTM_DELROUTE, RTN_BROADCAST, brd, 32,
+				  prim, 0);
+		if (!(ok & BRD0_OK))
+			fib_magic(RTM_DELROUTE, RTN_BROADCAST, any, 32,
+				  prim, 0);
+	}
+	if (!(ok & LOCAL_OK)) {
+		unsigned int addr_type;
+
+		fib_magic(RTM_DELROUTE, RTN_LOCAL, ifa->ifa_local, 32, prim, 0);
+
+		/* Check, that this local address finally disappeared. */
+		addr_type = inet_addr_type_dev_table(dev_net(dev), dev,
+						     ifa->ifa_local);
+		if (gone && addr_type != RTN_LOCAL) {
+			/* And the last, but not the least thing.
+			 * We must flush stray FIB entries.
+			 *
+			 * First of all, we scan fib_info list searching
+			 * for stray nexthop entries, then ignite fib_flush.
+			 */
+			if (fib_sync_down_addr(dev, ifa->ifa_local))
+				fib_flush(dev_net(dev));
+		}
+	}
+#undef LOCAL_OK
+#undef BRD_OK
+#undef BRD0_OK
+#undef BRD1_OK
+}
+
+static void nl_fib_lookup(struct net *net, struct fib_result_nl *frn)
+{
+
+	struct fib_result       res;
+	struct flowi4           fl4 = {
+		.flowi4_mark = frn->fl_mark,
+		.daddr = frn->fl_addr,
+		.flowi4_tos = frn->fl_tos,
+		.flowi4_scope = frn->fl_scope,
+	};
+	struct fib_table *tb;
+
+	rcu_read_lock();
+
+	tb = fib_get_table(net, frn->tb_id_in);
+
+	frn->err = -ENOENT;
+	if (tb) {
+		local_bh_disable();
+
+		frn->tb_id = tb->tb_id;
+		frn->err = fib_table_lookup(tb, &fl4, &res, FIB_LOOKUP_NOREF);
+
+		if (!frn->err) {
+			frn->prefixlen = res.prefixlen;
+			frn->nh_sel = res.nh_sel;
+			frn->type = res.type;
+			frn->scope = res.scope;
+		}
+		local_bh_enable();
+	}
+
+	rcu_read_unlock();
+}
+
+static void nl_fib_input(struct sk_buff *skb)
+{
+	struct net *net;
+	struct fib_result_nl *frn;
+	struct nlmsghdr *nlh;
+	u32 portid;
+
+	net = sock_net(skb->sk);
+	nlh = nlmsg_hdr(skb);
+	if (skb->len < nlmsg_total_size(sizeof(*frn)) ||
+	    skb->len < nlh->nlmsg_len ||
+	    nlmsg_len(nlh) < sizeof(*frn))
+		return;
+
+	skb = netlink_skb_clone(skb, GFP_KERNEL);
+	if (!skb)
+		return;
+	nlh = nlmsg_hdr(skb);
+
+	frn = (struct fib_result_nl *) nlmsg_data(nlh);
+	nl_fib_lookup(net, frn);
+
+	portid = NETLINK_CB(skb).portid;      /* netlink portid */
+	NETLINK_CB(skb).portid = 0;        /* from kernel */
+	NETLINK_CB(skb).dst_group = 0;  /* unicast */
+	netlink_unicast(net->ipv4.fibnl, skb, portid, MSG_DONTWAIT);
+}
+
+static int __net_init nl_fib_lookup_init(struct net *net)
+{
+	struct sock *sk;
+	struct netlink_kernel_cfg cfg = {
+		.input	= nl_fib_input,
+	};
+
+	sk = netlink_kernel_create(net, NETLINK_FIB_LOOKUP, &cfg);
+	if (!sk)
+		return -EAFNOSUPPORT;
+	net->ipv4.fibnl = sk;
+	return 0;
+}
+
+static void nl_fib_lookup_exit(struct net *net)
+{
+	netlink_kernel_release(net->ipv4.fibnl);
+	net->ipv4.fibnl = NULL;
+}
+
+static void fib_disable_ip(struct net_device *dev, unsigned long event,
+			   bool force)
+{
+	if (fib_sync_down_dev(dev, event, force))
+		fib_flush(dev_net(dev));
+	else
+		rt_cache_flush(dev_net(dev));
+	arp_ifdown(dev);
+}
+
+static int fib_inetaddr_event(struct notifier_block *this, unsigned long event, void *ptr)
+{
+	struct in_ifaddr *ifa = (struct in_ifaddr *)ptr;
+	struct net_device *dev = ifa->ifa_dev->dev;
+	struct net *net = dev_net(dev);
+
+	switch (event) {
+	case NETDEV_UP:
+		fib_add_ifaddr(ifa);
+#ifdef CONFIG_IP_ROUTE_MULTIPATH
+		fib_sync_up(dev, RTNH_F_DEAD);
+#endif
+		atomic_inc(&net->ipv4.dev_addr_genid);
+		rt_cache_flush(dev_net(dev));
+		break;
+	case NETDEV_DOWN:
+		fib_del_ifaddr(ifa, NULL);
+		atomic_inc(&net->ipv4.dev_addr_genid);
+		if (!ifa->ifa_dev->ifa_list) {
+			/* Last address was deleted from this interface.
+			 * Disable IP.
+			 */
+			fib_disable_ip(dev, event, true);
+		} else {
+			rt_cache_flush(dev_net(dev));
+		}
+		break;
+	}
+	return NOTIFY_DONE;
+}
+
+static int fib_netdev_event(struct notifier_block *this, unsigned long event, void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+	struct netdev_notifier_changeupper_info *upper_info = ptr;
+	struct netdev_notifier_info_ext *info_ext = ptr;
+	struct in_device *in_dev;
+	struct net *net = dev_net(dev);
+	unsigned int flags;
+
+	if (event == NETDEV_UNREGISTER) {
+		fib_disable_ip(dev, event, true);
+		rt_flush_dev(dev);
+		return NOTIFY_DONE;
+	}
+
+	in_dev = __in_dev_get_rtnl(dev);
+	if (!in_dev)
+		return NOTIFY_DONE;
+
+	switch (event) {
+	case NETDEV_UP:
+		for_ifa(in_dev) {
+			fib_add_ifaddr(ifa);
+		} endfor_ifa(in_dev);
+#ifdef CONFIG_IP_ROUTE_MULTIPATH
+		fib_sync_up(dev, RTNH_F_DEAD);
+#endif
+		atomic_inc(&net->ipv4.dev_addr_genid);
+		rt_cache_flush(net);
+		break;
+	case NETDEV_DOWN:
+		fib_disable_ip(dev, event, false);
+		break;
+	case NETDEV_CHANGE:
+		flags = dev_get_flags(dev);
+		if (flags & (IFF_RUNNING | IFF_LOWER_UP))
+			fib_sync_up(dev, RTNH_F_LINKDOWN);
+		else
+			fib_sync_down_dev(dev, event, false);
+		rt_cache_flush(net);
+		break;
+	case NETDEV_CHANGEMTU:
+		fib_sync_mtu(dev, info_ext->ext.mtu);
+		rt_cache_flush(net);
+		break;
+	case NETDEV_CHANGEUPPER:
+		upper_info = ptr;
+		/* flush all routes if dev is linked to or unlinked from
+		 * an L3 master device (e.g., VRF)
+		 */
+		if (upper_info->upper_dev &&
+		    netif_is_l3_master(upper_info->upper_dev))
+			fib_disable_ip(dev, NETDEV_DOWN, true);
+		break;
+	}
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block fib_inetaddr_notifier = {
+	.notifier_call = fib_inetaddr_event,
+};
+
+static struct notifier_block fib_netdev_notifier = {
+	.notifier_call = fib_netdev_event,
+};
+
+static int __net_init ip_fib_net_init(struct net *net)
+{
+	int err;
+	size_t size = sizeof(struct hlist_head) * FIB_TABLE_HASHSZ;
+
+	err = fib4_notifier_init(net);
+	if (err)
+		return err;
+
+	/* Avoid false sharing : Use at least a full cache line */
+	size = max_t(size_t, size, L1_CACHE_BYTES);
+
+	net->ipv4.fib_table_hash = kzalloc(size, GFP_KERNEL);
+	if (!net->ipv4.fib_table_hash) {
+		err = -ENOMEM;
+		goto err_table_hash_alloc;
+	}
+
+	err = fib4_rules_init(net);
+	if (err < 0)
+		goto err_rules_init;
+	return 0;
+
+err_rules_init:
+	kfree(net->ipv4.fib_table_hash);
+err_table_hash_alloc:
+	fib4_notifier_exit(net);
+	return err;
+}
+
+static void ip_fib_net_exit(struct net *net)
+{
+	int i;
+
+	rtnl_lock();
+#ifdef CONFIG_IP_MULTIPLE_TABLES
+	RCU_INIT_POINTER(net->ipv4.fib_main, NULL);
+	RCU_INIT_POINTER(net->ipv4.fib_default, NULL);
+#endif
+	/* Destroy the tables in reverse order to guarantee that the
+	 * local table, ID 255, is destroyed before the main table, ID
+	 * 254. This is necessary as the local table may contain
+	 * references to data contained in the main table.
+	 */
+	for (i = FIB_TABLE_HASHSZ - 1; i >= 0; i--) {
+		struct hlist_head *head = &net->ipv4.fib_table_hash[i];
+		struct hlist_node *tmp;
+		struct fib_table *tb;
+
+		hlist_for_each_entry_safe(tb, tmp, head, tb_hlist) {
+			hlist_del(&tb->tb_hlist);
+			fib_table_flush(net, tb, true);
+			fib_free_table(tb);
+		}
+	}
+
+#ifdef CONFIG_IP_MULTIPLE_TABLES
+	fib4_rules_exit(net);
+#endif
+	rtnl_unlock();
+	kfree(net->ipv4.fib_table_hash);
+	fib4_notifier_exit(net);
+}
+
+static int __net_init fib_net_init(struct net *net)
+{
+	int error;
+
+#ifdef CONFIG_IP_ROUTE_CLASSID
+	net->ipv4.fib_num_tclassid_users = 0;
+#endif
+	error = ip_fib_net_init(net);
+	if (error < 0)
+		goto out;
+	error = nl_fib_lookup_init(net);
+	if (error < 0)
+		goto out_nlfl;
+	error = fib_proc_init(net);
+	if (error < 0)
+		goto out_proc;
+out:
+	return error;
+
+out_proc:
+	nl_fib_lookup_exit(net);
+out_nlfl:
+	ip_fib_net_exit(net);
+	goto out;
+}
+
+static void __net_exit fib_net_exit(struct net *net)
+{
+	fib_proc_exit(net);
+	nl_fib_lookup_exit(net);
+	ip_fib_net_exit(net);
+}
+
+static struct pernet_operations fib_net_ops = {
+	.init = fib_net_init,
+	.exit = fib_net_exit,
+};
+
+void __init ip_fib_init(void)
+{
+	fib_trie_init();
+
+	register_pernet_subsys(&fib_net_ops);
+
+	register_netdevice_notifier(&fib_netdev_notifier);
+	register_inetaddr_notifier(&fib_inetaddr_notifier);
+
+	rtnl_register(PF_INET, RTM_NEWROUTE, inet_rtm_newroute, NULL, 0);
+	rtnl_register(PF_INET, RTM_DELROUTE, inet_rtm_delroute, NULL, 0);
+	rtnl_register(PF_INET, RTM_GETROUTE, NULL, inet_dump_fib, 0);
+}