// SPDX-License-Identifier: GPL-2.0-only

  #include <linux/types.h>
  #include <linux/skbuff.h>
  #include <linux/socket.h>

  #include <linux/sysctl.h>

  #include <linux/net.h>
  #include <linux/module.h>
  #include <linux/if_arp.h>
  #include <linux/ipv6.h>
  #include <linux/mpls.h>

  #include <linux/netconf.h>

  #include <linux/nospec.h>

  #include <linux/vmalloc.h>

  #include <linux/percpu.h>

  #include <net/ip.h>
  #include <net/dst.h>
  #include <net/sock.h>
  #include <net/arp.h>
  #include <net/ip_fib.h>
  #include <net/netevent.h>

  #include <net/ip_tunnels.h>

  #include <net/netns/generic.h>

  #if IS_ENABLED(CONFIG_IPV6)
  #include <net/ipv6.h>

  #endif

  #include <net/ipv6_stubs.h>

  #include <net/rtnh.h>

  #include "internal.h"

  /* max memory we will use for mpls_route */
  #define MAX_MPLS_ROUTE_MEM	4096

  /* Maximum number of labels to look ahead at when selecting a path of
   * a multipath route
   */
  #define MAX_MP_SELECT_LABELS 4

  #define MPLS_NEIGH_TABLE_UNSPEC (NEIGH_LINK_TABLE + 1)

  static int label_limit = (1 << 20) - 1;

  static int ttl_max = 255;

  #if IS_ENABLED(CONFIG_NET_IP_TUNNEL)

  static size_t ipgre_mpls_encap_hlen(struct ip_tunnel_encap *e)

  {
  	return sizeof(struct mpls_shim_hdr);
  }
  
  static const struct ip_tunnel_encap_ops mpls_iptun_ops = {
  	.encap_hlen	= ipgre_mpls_encap_hlen,
  };
  
  static int ipgre_tunnel_encap_add_mpls_ops(void)
  {
  	return ip_tunnel_encap_add_ops(&mpls_iptun_ops, TUNNEL_ENCAP_MPLS);
  }
  
  static void ipgre_tunnel_encap_del_mpls_ops(void)
  {
  	ip_tunnel_encap_del_ops(&mpls_iptun_ops, TUNNEL_ENCAP_MPLS);
  }
  #else
  static int ipgre_tunnel_encap_add_mpls_ops(void)
  {
  	return 0;
  }
  
  static void ipgre_tunnel_encap_del_mpls_ops(void)
  {
  }
  #endif

  static void rtmsg_lfib(int event, u32 label, struct mpls_route *rt,
  		       struct nlmsghdr *nlh, struct net *net, u32 portid,
  		       unsigned int nlm_flags);

  static struct mpls_route *mpls_route_input_rcu(struct net *net, unsigned index)
  {
  	struct mpls_route *rt = NULL;
  
  	if (index < net->mpls.platform_labels) {
  		struct mpls_route __rcu **platform_label =
  			rcu_dereference(net->mpls.platform_label);
  		rt = rcu_dereference(platform_label[index]);
  	}
  	return rt;
  }

  bool mpls_output_possible(const struct net_device *dev)

  {
  	return dev && (dev->flags & IFF_UP) && netif_carrier_ok(dev);
  }

  EXPORT_SYMBOL_GPL(mpls_output_possible);

  static u8 *__mpls_nh_via(struct mpls_route *rt, struct mpls_nh *nh)
  {

  	return (u8 *)nh + rt->rt_via_offset;

  }
  
  static const u8 *mpls_nh_via(const struct mpls_route *rt,
  			     const struct mpls_nh *nh)
  {
  	return __mpls_nh_via((struct mpls_route *)rt, (struct mpls_nh *)nh);
  }

  static unsigned int mpls_nh_header_size(const struct mpls_nh *nh)

  {
  	/* The size of the layer 2.5 labels to be added for this route */

  	return nh->nh_labels * sizeof(struct mpls_shim_hdr);

  }

  unsigned int mpls_dev_mtu(const struct net_device *dev)

  {
  	/* The amount of data the layer 2 frame can hold */
  	return dev->mtu;
  }

  EXPORT_SYMBOL_GPL(mpls_dev_mtu);

  bool mpls_pkt_too_big(const struct sk_buff *skb, unsigned int mtu)

  {
  	if (skb->len <= mtu)
  		return false;

  	if (skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu))

  		return false;
  
  	return true;
  }

  EXPORT_SYMBOL_GPL(mpls_pkt_too_big);

  void mpls_stats_inc_outucastpkts(struct net_device *dev,
  				 const struct sk_buff *skb)
  {
  	struct mpls_dev *mdev;
  
  	if (skb->protocol == htons(ETH_P_MPLS_UC)) {
  		mdev = mpls_dev_get(dev);
  		if (mdev)
  			MPLS_INC_STATS_LEN(mdev, skb->len,
  					   tx_packets,
  					   tx_bytes);
  	} else if (skb->protocol == htons(ETH_P_IP)) {
  		IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
  #if IS_ENABLED(CONFIG_IPV6)
  	} else if (skb->protocol == htons(ETH_P_IPV6)) {
  		struct inet6_dev *in6dev = __in6_dev_get(dev);
  
  		if (in6dev)
  			IP6_UPD_PO_STATS(dev_net(dev), in6dev,
  					 IPSTATS_MIB_OUT, skb->len);
  #endif
  	}
  }
  EXPORT_SYMBOL_GPL(mpls_stats_inc_outucastpkts);

  static u32 mpls_multipath_hash(struct mpls_route *rt, struct sk_buff *skb)

  {

  	struct mpls_entry_decoded dec;

  	unsigned int mpls_hdr_len = 0;

  	struct mpls_shim_hdr *hdr;
  	bool eli_seen = false;
  	int label_index;

  	u32 hash = 0;

  	for (label_index = 0; label_index < MAX_MP_SELECT_LABELS;

  	     label_index++) {

  		mpls_hdr_len += sizeof(*hdr);
  		if (!pskb_may_pull(skb, mpls_hdr_len))

  			break;
  
  		/* Read and decode the current label */
  		hdr = mpls_hdr(skb) + label_index;
  		dec = mpls_entry_decode(hdr);
  
  		/* RFC6790 - reserved labels MUST NOT be used as keys
  		 * for the load-balancing function
  		 */
  		if (likely(dec.label >= MPLS_LABEL_FIRST_UNRESERVED)) {
  			hash = jhash_1word(dec.label, hash);
  
  			/* The entropy label follows the entropy label
  			 * indicator, so this means that the entropy
  			 * label was just added to the hash - no need to
  			 * go any deeper either in the label stack or in the
  			 * payload
  			 */
  			if (eli_seen)
  				break;
  		} else if (dec.label == MPLS_LABEL_ENTROPY) {
  			eli_seen = true;
  		}

  		if (!dec.bos)
  			continue;
  
  		/* found bottom label; does skb have room for a header? */
  		if (pskb_may_pull(skb, mpls_hdr_len + sizeof(struct iphdr))) {

  			const struct iphdr *v4hdr;

  			v4hdr = (const struct iphdr *)(hdr + 1);

  			if (v4hdr->version == 4) {
  				hash = jhash_3words(ntohl(v4hdr->saddr),
  						    ntohl(v4hdr->daddr),
  						    v4hdr->protocol, hash);
  			} else if (v4hdr->version == 6 &&

  				   pskb_may_pull(skb, mpls_hdr_len +
  						 sizeof(struct ipv6hdr))) {

  				const struct ipv6hdr *v6hdr;

  				v6hdr = (const struct ipv6hdr *)(hdr + 1);

  				hash = __ipv6_addr_jhash(&v6hdr->saddr, hash);
  				hash = __ipv6_addr_jhash(&v6hdr->daddr, hash);
  				hash = jhash_1word(v6hdr->nexthdr, hash);
  			}
  		}

  
  		break;

  	}

  	return hash;
  }

  static struct mpls_nh *mpls_get_nexthop(struct mpls_route *rt, u8 index)
  {
  	return (struct mpls_nh *)((u8 *)rt->rt_nh + index * rt->rt_nh_size);
  }

  /* number of alive nexthops (rt->rt_nhn_alive) and the flags for
   * a next hop (nh->nh_flags) are modified by netdev event handlers.
   * Since those fields can change at any moment, use READ_ONCE to
   * access both.
   */

  static struct mpls_nh *mpls_select_multipath(struct mpls_route *rt,

  					     struct sk_buff *skb)

  {

  	u32 hash = 0;
  	int nh_index = 0;
  	int n = 0;

  	u8 alive;

  
  	/* No need to look further into packet if there's only
  	 * one path
  	 */
  	if (rt->rt_nhn == 1)

  		return rt->rt_nh;

  	alive = READ_ONCE(rt->rt_nhn_alive);
  	if (alive == 0)

  		return NULL;

  	hash = mpls_multipath_hash(rt, skb);

  	nh_index = hash % alive;
  	if (alive == rt->rt_nhn)
  		goto out;
  	for_nexthops(rt) {

  		unsigned int nh_flags = READ_ONCE(nh->nh_flags);
  
  		if (nh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))

  			continue;
  		if (n == nh_index)
  			return nh;
  		n++;
  	} endfor_nexthops(rt);

  out:

  	return mpls_get_nexthop(rt, nh_index);

  }

  static bool mpls_egress(struct net *net, struct mpls_route *rt,
  			struct sk_buff *skb, struct mpls_entry_decoded dec)

  {

  	enum mpls_payload_type payload_type;
  	bool success = false;

  	/* The IPv4 code below accesses through the IPv4 header
  	 * checksum, which is 12 bytes into the packet.
  	 * The IPv6 code below accesses through the IPv6 hop limit
  	 * which is 8 bytes into the packet.
  	 *
  	 * For all supported cases there should always be at least 12
  	 * bytes of packet data present.  The IPv4 header is 20 bytes
  	 * without options and the IPv6 header is always 40 bytes
  	 * long.
  	 */
  	if (!pskb_may_pull(skb, 12))
  		return false;

  	payload_type = rt->rt_payload_type;
  	if (payload_type == MPT_UNSPEC)
  		payload_type = ip_hdr(skb)->version;
  
  	switch (payload_type) {
  	case MPT_IPV4: {
  		struct iphdr *hdr4 = ip_hdr(skb);

  		u8 new_ttl;

  		skb->protocol = htons(ETH_P_IP);

  
  		/* If propagating TTL, take the decremented TTL from
  		 * the incoming MPLS header, otherwise decrement the
  		 * TTL, but only if not 0 to avoid underflow.
  		 */
  		if (rt->rt_ttl_propagate == MPLS_TTL_PROP_ENABLED ||
  		    (rt->rt_ttl_propagate == MPLS_TTL_PROP_DEFAULT &&
  		     net->mpls.ip_ttl_propagate))
  			new_ttl = dec.ttl;
  		else
  			new_ttl = hdr4->ttl ? hdr4->ttl - 1 : 0;

  		csum_replace2(&hdr4->check,
  			      htons(hdr4->ttl << 8),

  			      htons(new_ttl << 8));
  		hdr4->ttl = new_ttl;

  		success = true;
  		break;

  	}

  	case MPT_IPV6: {

  		struct ipv6hdr *hdr6 = ipv6_hdr(skb);
  		skb->protocol = htons(ETH_P_IPV6);

  
  		/* If propagating TTL, take the decremented TTL from
  		 * the incoming MPLS header, otherwise decrement the
  		 * hop limit, but only if not 0 to avoid underflow.
  		 */
  		if (rt->rt_ttl_propagate == MPLS_TTL_PROP_ENABLED ||
  		    (rt->rt_ttl_propagate == MPLS_TTL_PROP_DEFAULT &&
  		     net->mpls.ip_ttl_propagate))
  			hdr6->hop_limit = dec.ttl;
  		else if (hdr6->hop_limit)
  			hdr6->hop_limit = hdr6->hop_limit - 1;

  		success = true;
  		break;

  	}

  	case MPT_UNSPEC:

  		/* Should have decided which protocol it is by now */

  		break;
  	}

  	return success;
  }
  
  static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
  			struct packet_type *pt, struct net_device *orig_dev)
  {
  	struct net *net = dev_net(dev);
  	struct mpls_shim_hdr *hdr;
  	struct mpls_route *rt;

  	struct mpls_nh *nh;

  	struct mpls_entry_decoded dec;
  	struct net_device *out_dev;

  	struct mpls_dev *out_mdev;

  	struct mpls_dev *mdev;

  	unsigned int hh_len;
  	unsigned int new_header_size;
  	unsigned int mtu;
  	int err;
  
  	/* Careful this entire function runs inside of an rcu critical section */

  	mdev = mpls_dev_get(dev);

  	if (!mdev)

  		goto drop;

  	MPLS_INC_STATS_LEN(mdev, skb->len, rx_packets,
  			   rx_bytes);
  
  	if (!mdev->input_enabled) {
  		MPLS_INC_STATS(mdev, rx_dropped);

  		goto drop;

  	}
  
  	if (skb->pkt_type != PACKET_HOST)
  		goto err;

  
  	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)

  		goto err;

  
  	if (!pskb_may_pull(skb, sizeof(*hdr)))

  		goto err;

  
  	/* Read and decode the label */
  	hdr = mpls_hdr(skb);
  	dec = mpls_entry_decode(hdr);

  	rt = mpls_route_input_rcu(net, dec.label);

  	if (!rt) {
  		MPLS_INC_STATS(mdev, rx_noroute);

  		goto drop;

  	}

  	nh = mpls_select_multipath(rt, skb);

  	if (!nh)

  		goto err;

  	/* Pop the label */
  	skb_pull(skb, sizeof(*hdr));
  	skb_reset_network_header(skb);
  
  	skb_orphan(skb);

  	if (skb_warn_if_lro(skb))

  		goto err;

  
  	skb_forward_csum(skb);
  
  	/* Verify ttl is valid */

  	if (dec.ttl <= 1)

  		goto err;

  	dec.ttl -= 1;

  	/* Find the output device */
  	out_dev = rcu_dereference(nh->nh_dev);
  	if (!mpls_output_possible(out_dev))
  		goto tx_err;

  	/* Verify the destination can hold the packet */

  	new_header_size = mpls_nh_header_size(nh);

  	mtu = mpls_dev_mtu(out_dev);
  	if (mpls_pkt_too_big(skb, mtu - new_header_size))

  		goto tx_err;

  
  	hh_len = LL_RESERVED_SPACE(out_dev);
  	if (!out_dev->header_ops)
  		hh_len = 0;
  
  	/* Ensure there is enough space for the headers in the skb */
  	if (skb_cow(skb, hh_len + new_header_size))

  		goto tx_err;

  
  	skb->dev = out_dev;
  	skb->protocol = htons(ETH_P_MPLS_UC);
  
  	if (unlikely(!new_header_size && dec.bos)) {
  		/* Penultimate hop popping */

  		if (!mpls_egress(dev_net(out_dev), rt, skb, dec))

  			goto err;

  	} else {
  		bool bos;
  		int i;
  		skb_push(skb, new_header_size);
  		skb_reset_network_header(skb);
  		/* Push the new labels */
  		hdr = mpls_hdr(skb);
  		bos = dec.bos;

  		for (i = nh->nh_labels - 1; i >= 0; i--) {
  			hdr[i] = mpls_entry_encode(nh->nh_label[i],
  						   dec.ttl, 0, bos);

  			bos = false;
  		}
  	}

  	mpls_stats_inc_outucastpkts(out_dev, skb);

  	/* If via wasn't specified then send out using device address */
  	if (nh->nh_via_table == MPLS_NEIGH_TABLE_UNSPEC)
  		err = neigh_xmit(NEIGH_LINK_TABLE, out_dev,
  				 out_dev->dev_addr, skb);
  	else
  		err = neigh_xmit(nh->nh_via_table, out_dev,
  				 mpls_nh_via(rt, nh), skb);

  	if (err)
  		net_dbg_ratelimited("%s: packet transmission failed: %d
  ",
  				    __func__, err);
  	return 0;

  tx_err:
  	out_mdev = out_dev ? mpls_dev_get(out_dev) : NULL;
  	if (out_mdev)
  		MPLS_INC_STATS(out_mdev, tx_errors);
  	goto drop;
  err:
  	MPLS_INC_STATS(mdev, rx_errors);

  drop:
  	kfree_skb(skb);
  	return NET_RX_DROP;
  }
  
  static struct packet_type mpls_packet_type __read_mostly = {
  	.type = cpu_to_be16(ETH_P_MPLS_UC),
  	.func = mpls_forward,
  };

  static const struct nla_policy rtm_mpls_policy[RTA_MAX+1] = {

  	[RTA_DST]		= { .type = NLA_U32 },
  	[RTA_OIF]		= { .type = NLA_U32 },

  	[RTA_TTL_PROPAGATE]	= { .type = NLA_U8 },

  };

  struct mpls_route_config {

  	u32			rc_protocol;
  	u32			rc_ifindex;

  	u8			rc_via_table;
  	u8			rc_via_alen;

  	u8			rc_via[MAX_VIA_ALEN];
  	u32			rc_label;

  	u8			rc_ttl_propagate;

  	u8			rc_output_labels;

  	u32			rc_output_label[MAX_NEW_LABELS];
  	u32			rc_nlflags;
  	enum mpls_payload_type	rc_payload_type;
  	struct nl_info		rc_nlinfo;

  	struct rtnexthop	*rc_mp;
  	int			rc_mp_len;

  };

  /* all nexthops within a route have the same size based on max
   * number of labels and max via length for a hop
   */
  static struct mpls_route *mpls_rt_alloc(u8 num_nh, u8 max_alen, u8 max_labels)

  {

  	u8 nh_size = MPLS_NH_SIZE(max_labels, max_alen);

  	struct mpls_route *rt;

  	size_t size;

  	size = sizeof(*rt) + num_nh * nh_size;
  	if (size > MAX_MPLS_ROUTE_MEM)
  		return ERR_PTR(-EINVAL);
  
  	rt = kzalloc(size, GFP_KERNEL);
  	if (!rt)
  		return ERR_PTR(-ENOMEM);
  
  	rt->rt_nhn = num_nh;
  	rt->rt_nhn_alive = num_nh;
  	rt->rt_nh_size = nh_size;
  	rt->rt_via_offset = MPLS_NH_VIA_OFF(max_labels);

  	return rt;
  }
  
  static void mpls_rt_free(struct mpls_route *rt)
  {
  	if (rt)
  		kfree_rcu(rt, rt_rcu);
  }

  static void mpls_notify_route(struct net *net, unsigned index,
  			      struct mpls_route *old, struct mpls_route *new,
  			      const struct nl_info *info)
  {
  	struct nlmsghdr *nlh = info ? info->nlh : NULL;
  	unsigned portid = info ? info->portid : 0;
  	int event = new ? RTM_NEWROUTE : RTM_DELROUTE;
  	struct mpls_route *rt = new ? new : old;
  	unsigned nlm_flags = (old && new) ? NLM_F_REPLACE : 0;
  	/* Ignore reserved labels for now */

  	if (rt && (index >= MPLS_LABEL_FIRST_UNRESERVED))

  		rtmsg_lfib(event, index, rt, nlh, net, portid, nlm_flags);
  }

  static void mpls_route_update(struct net *net, unsigned index,

  			      struct mpls_route *new,

  			      const struct nl_info *info)
  {

  	struct mpls_route __rcu **platform_label;

  	struct mpls_route *rt;

  
  	ASSERT_RTNL();

  	platform_label = rtnl_dereference(net->mpls.platform_label);
  	rt = rtnl_dereference(platform_label[index]);

  	rcu_assign_pointer(platform_label[index], new);

  	mpls_notify_route(net, index, rt, new, info);

  	/* If we removed a route free it now */

  	mpls_rt_free(rt);

  }

  static unsigned find_free_label(struct net *net)
  {

  	struct mpls_route __rcu **platform_label;
  	size_t platform_labels;

  	unsigned index;

  
  	platform_label = rtnl_dereference(net->mpls.platform_label);
  	platform_labels = net->mpls.platform_labels;

  	for (index = MPLS_LABEL_FIRST_UNRESERVED; index < platform_labels;
  	     index++) {

  		if (!rtnl_dereference(platform_label[index]))

  			return index;
  	}
  	return LABEL_NOT_SPECIFIED;
  }

  #if IS_ENABLED(CONFIG_INET)

  static struct net_device *inet_fib_lookup_dev(struct net *net,
  					      const void *addr)

  {

  	struct net_device *dev;

  	struct rtable *rt;
  	struct in_addr daddr;
  
  	memcpy(&daddr, addr, sizeof(struct in_addr));
  	rt = ip_route_output(net, daddr.s_addr, 0, 0, 0);
  	if (IS_ERR(rt))

  		return ERR_CAST(rt);

  
  	dev = rt->dst.dev;
  	dev_hold(dev);
  
  	ip_rt_put(rt);

  	return dev;

  }
  #else

  static struct net_device *inet_fib_lookup_dev(struct net *net,
  					      const void *addr)

  {
  	return ERR_PTR(-EAFNOSUPPORT);

  }

  #endif

  #if IS_ENABLED(CONFIG_IPV6)

  static struct net_device *inet6_fib_lookup_dev(struct net *net,
  					       const void *addr)

  {

  	struct net_device *dev;

  	struct dst_entry *dst;
  	struct flowi6 fl6;

  
  	if (!ipv6_stub)
  		return ERR_PTR(-EAFNOSUPPORT);

  
  	memset(&fl6, 0, sizeof(fl6));
  	memcpy(&fl6.daddr, addr, sizeof(struct in6_addr));

  	dst = ipv6_stub->ipv6_dst_lookup_flow(net, NULL, &fl6, NULL);
  	if (IS_ERR(dst))
  		return ERR_CAST(dst);

  
  	dev = dst->dev;
  	dev_hold(dev);

  	dst_release(dst);
  
  	return dev;
  }

  #else

  static struct net_device *inet6_fib_lookup_dev(struct net *net,
  					       const void *addr)

  {
  	return ERR_PTR(-EAFNOSUPPORT);
  }
  #endif

  
  static struct net_device *find_outdev(struct net *net,

  				      struct mpls_route *rt,

  				      struct mpls_nh *nh, int oif)

  {
  	struct net_device *dev = NULL;

  	if (!oif) {
  		switch (nh->nh_via_table) {

  		case NEIGH_ARP_TABLE:

  			dev = inet_fib_lookup_dev(net, mpls_nh_via(rt, nh));

  			break;
  		case NEIGH_ND_TABLE:

  			dev = inet6_fib_lookup_dev(net, mpls_nh_via(rt, nh));

  			break;
  		case NEIGH_LINK_TABLE:
  			break;
  		}
  	} else {

  		dev = dev_get_by_index(net, oif);

  	}

  	if (!dev)
  		return ERR_PTR(-ENODEV);

  	if (IS_ERR(dev))
  		return dev;

  	/* The caller is holding rtnl anyways, so release the dev reference */
  	dev_put(dev);

  	return dev;
  }

  static int mpls_nh_assign_dev(struct net *net, struct mpls_route *rt,
  			      struct mpls_nh *nh, int oif)

  {
  	struct net_device *dev = NULL;
  	int err = -ENODEV;

  	dev = find_outdev(net, rt, nh, oif);

  	if (IS_ERR(dev)) {
  		err = PTR_ERR(dev);
  		dev = NULL;
  		goto errout;
  	}
  
  	/* Ensure this is a supported device */
  	err = -EINVAL;
  	if (!mpls_dev_get(dev))
  		goto errout;

  	if ((nh->nh_via_table == NEIGH_LINK_TABLE) &&
  	    (dev->addr_len != nh->nh_via_alen))
  		goto errout;

  	RCU_INIT_POINTER(nh->nh_dev, dev);

  	if (!(dev->flags & IFF_UP)) {
  		nh->nh_flags |= RTNH_F_DEAD;
  	} else {
  		unsigned int flags;
  
  		flags = dev_get_flags(dev);
  		if (!(flags & (IFF_RUNNING | IFF_LOWER_UP)))
  			nh->nh_flags |= RTNH_F_LINKDOWN;
  	}

  	return 0;
  
  errout:
  	return err;
  }

  static int nla_get_via(const struct nlattr *nla, u8 *via_alen, u8 *via_table,
  		       u8 via_addr[], struct netlink_ext_ack *extack)
  {
  	struct rtvia *via = nla_data(nla);
  	int err = -EINVAL;
  	int alen;
  
  	if (nla_len(nla) < offsetof(struct rtvia, rtvia_addr)) {
  		NL_SET_ERR_MSG_ATTR(extack, nla,
  				    "Invalid attribute length for RTA_VIA");
  		goto errout;
  	}
  	alen = nla_len(nla) -
  			offsetof(struct rtvia, rtvia_addr);
  	if (alen > MAX_VIA_ALEN) {
  		NL_SET_ERR_MSG_ATTR(extack, nla,
  				    "Invalid address length for RTA_VIA");
  		goto errout;
  	}
  
  	/* Validate the address family */
  	switch (via->rtvia_family) {
  	case AF_PACKET:
  		*via_table = NEIGH_LINK_TABLE;
  		break;
  	case AF_INET:
  		*via_table = NEIGH_ARP_TABLE;
  		if (alen != 4)
  			goto errout;
  		break;
  	case AF_INET6:
  		*via_table = NEIGH_ND_TABLE;
  		if (alen != 16)
  			goto errout;
  		break;
  	default:
  		/* Unsupported address family */
  		goto errout;
  	}
  
  	memcpy(via_addr, via->rtvia_addr, alen);
  	*via_alen = alen;
  	err = 0;
  
  errout:
  	return err;
  }

  static int mpls_nh_build_from_cfg(struct mpls_route_config *cfg,
  				  struct mpls_route *rt)
  {
  	struct net *net = cfg->rc_nlinfo.nl_net;
  	struct mpls_nh *nh = rt->rt_nh;
  	int err;
  	int i;
  
  	if (!nh)
  		return -ENOMEM;

  	nh->nh_labels = cfg->rc_output_labels;
  	for (i = 0; i < nh->nh_labels; i++)
  		nh->nh_label[i] = cfg->rc_output_label[i];
  
  	nh->nh_via_table = cfg->rc_via_table;

  	memcpy(__mpls_nh_via(rt, nh), cfg->rc_via, cfg->rc_via_alen);

  	nh->nh_via_alen = cfg->rc_via_alen;

  	err = mpls_nh_assign_dev(net, rt, nh, cfg->rc_ifindex);

  	if (err)
  		goto errout;

  	if (nh->nh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))
  		rt->rt_nhn_alive--;

  	return 0;
  
  errout:
  	return err;
  }

  static int mpls_nh_build(struct net *net, struct mpls_route *rt,

  			 struct mpls_nh *nh, int oif, struct nlattr *via,

  			 struct nlattr *newdst, u8 max_labels,
  			 struct netlink_ext_ack *extack)

  {
  	int err = -ENOMEM;
  
  	if (!nh)
  		goto errout;
  
  	if (newdst) {

  		err = nla_get_labels(newdst, max_labels, &nh->nh_labels,

  				     nh->nh_label, extack);

  		if (err)
  			goto errout;
  	}

  	if (via) {
  		err = nla_get_via(via, &nh->nh_via_alen, &nh->nh_via_table,

  				  __mpls_nh_via(rt, nh), extack);

  		if (err)
  			goto errout;
  	} else {
  		nh->nh_via_table = MPLS_NEIGH_TABLE_UNSPEC;
  	}

  	err = mpls_nh_assign_dev(net, rt, nh, oif);

  	if (err)
  		goto errout;
  
  	return 0;
  
  errout:
  	return err;
  }

  static u8 mpls_count_nexthops(struct rtnexthop *rtnh, int len,

  			      u8 cfg_via_alen, u8 *max_via_alen,
  			      u8 *max_labels)

  {

  	int remaining = len;

  	u8 nhs = 0;

  	*max_via_alen = 0;

  	*max_labels = 0;

  	while (rtnh_ok(rtnh, remaining)) {

  		struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
  		int attrlen;

  		u8 n_labels = 0;

  
  		attrlen = rtnh_attrlen(rtnh);
  		nla = nla_find(attrs, attrlen, RTA_VIA);
  		if (nla && nla_len(nla) >=
  		    offsetof(struct rtvia, rtvia_addr)) {
  			int via_alen = nla_len(nla) -
  				offsetof(struct rtvia, rtvia_addr);
  
  			if (via_alen <= MAX_VIA_ALEN)
  				*max_via_alen = max_t(u16, *max_via_alen,
  						      via_alen);
  		}

  		nla = nla_find(attrs, attrlen, RTA_NEWDST);
  		if (nla &&

  		    nla_get_labels(nla, MAX_NEW_LABELS, &n_labels,
  				   NULL, NULL) != 0)

  			return 0;
  
  		*max_labels = max_t(u8, *max_labels, n_labels);

  		/* number of nexthops is tracked by a u8.
  		 * Check for overflow.
  		 */
  		if (nhs == 255)
  			return 0;

  		nhs++;

  		rtnh = rtnh_next(rtnh, &remaining);
  	}
  
  	/* leftover implies invalid nexthop configuration, discard it */
  	return remaining > 0 ? 0 : nhs;
  }
  
  static int mpls_nh_build_multi(struct mpls_route_config *cfg,

  			       struct mpls_route *rt, u8 max_labels,
  			       struct netlink_ext_ack *extack)

  {
  	struct rtnexthop *rtnh = cfg->rc_mp;
  	struct nlattr *nla_via, *nla_newdst;
  	int remaining = cfg->rc_mp_len;

  	int err = 0;

  	u8 nhs = 0;

  
  	change_nexthops(rt) {
  		int attrlen;
  
  		nla_via = NULL;
  		nla_newdst = NULL;
  
  		err = -EINVAL;
  		if (!rtnh_ok(rtnh, remaining))
  			goto errout;

  		/* neither weighted multipath nor any flags
  		 * are supported
  		 */
  		if (rtnh->rtnh_hops || rtnh->rtnh_flags)
  			goto errout;

  		attrlen = rtnh_attrlen(rtnh);
  		if (attrlen > 0) {
  			struct nlattr *attrs = rtnh_attrs(rtnh);
  
  			nla_via = nla_find(attrs, attrlen, RTA_VIA);
  			nla_newdst = nla_find(attrs, attrlen, RTA_NEWDST);
  		}

  		err = mpls_nh_build(cfg->rc_nlinfo.nl_net, rt, nh,

  				    rtnh->rtnh_ifindex, nla_via, nla_newdst,

  				    max_labels, extack);

  		if (err)
  			goto errout;

  		if (nh->nh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))
  			rt->rt_nhn_alive--;

  		rtnh = rtnh_next(rtnh, &remaining);
  		nhs++;
  	} endfor_nexthops(rt);
  
  	rt->rt_nhn = nhs;
  
  	return 0;
  
  errout:
  	return err;
  }

  static bool mpls_label_ok(struct net *net, unsigned int *index,

  			  struct netlink_ext_ack *extack)

  {

  	bool is_ok = true;

  	/* Reserved labels may not be set */

  	if (*index < MPLS_LABEL_FIRST_UNRESERVED) {

  		NL_SET_ERR_MSG(extack,
  			       "Invalid label - must be MPLS_LABEL_FIRST_UNRESERVED or higher");

  		is_ok = false;

  	}

  
  	/* The full 20 bit range may not be supported. */

  	if (is_ok && *index >= net->mpls.platform_labels) {

  		NL_SET_ERR_MSG(extack,
  			       "Label >= configured maximum in platform_labels");

  		is_ok = false;

  	}

  	*index = array_index_nospec(*index, net->mpls.platform_labels);
  	return is_ok;

  }

  static int mpls_route_add(struct mpls_route_config *cfg,
  			  struct netlink_ext_ack *extack)

  {

  	struct mpls_route __rcu **platform_label;

  	struct net *net = cfg->rc_nlinfo.nl_net;

  	struct mpls_route *rt, *old;

  	int err = -EINVAL;

  	u8 max_via_alen;

  	unsigned index;

  	u8 max_labels;

  	u8 nhs;

  
  	index = cfg->rc_label;
  
  	/* If a label was not specified during insert pick one */
  	if ((index == LABEL_NOT_SPECIFIED) &&
  	    (cfg->rc_nlflags & NLM_F_CREATE)) {
  		index = find_free_label(net);
  	}

  	if (!mpls_label_ok(net, &index, extack))

  		goto errout;

  	/* Append makes no sense with mpls */

  	err = -EOPNOTSUPP;

  	if (cfg->rc_nlflags & NLM_F_APPEND) {
  		NL_SET_ERR_MSG(extack, "MPLS does not support route append");

  		goto errout;

  	}

  
  	err = -EEXIST;

  	platform_label = rtnl_dereference(net->mpls.platform_label);
  	old = rtnl_dereference(platform_label[index]);

  	if ((cfg->rc_nlflags & NLM_F_EXCL) && old)
  		goto errout;
  
  	err = -EEXIST;
  	if (!(cfg->rc_nlflags & NLM_F_REPLACE) && old)
  		goto errout;
  
  	err = -ENOENT;
  	if (!(cfg->rc_nlflags & NLM_F_CREATE) && !old)
  		goto errout;

  	err = -EINVAL;

  	if (cfg->rc_mp) {
  		nhs = mpls_count_nexthops(cfg->rc_mp, cfg->rc_mp_len,
  					  cfg->rc_via_alen, &max_via_alen,
  					  &max_labels);
  	} else {
  		max_via_alen = cfg->rc_via_alen;
  		max_labels = cfg->rc_output_labels;
  		nhs = 1;
  	}

  	if (nhs == 0) {
  		NL_SET_ERR_MSG(extack, "Route does not contain a nexthop");

  		goto errout;

  	}

  	err = -ENOMEM;

  	rt = mpls_rt_alloc(nhs, max_via_alen, max_labels);

  	if (IS_ERR(rt)) {
  		err = PTR_ERR(rt);

  		goto errout;

  	}

  	rt->rt_protocol = cfg->rc_protocol;

  	rt->rt_payload_type = cfg->rc_payload_type;

  	rt->rt_ttl_propagate = cfg->rc_ttl_propagate;

  	if (cfg->rc_mp)

  		err = mpls_nh_build_multi(cfg, rt, max_labels, extack);

  	else
  		err = mpls_nh_build_from_cfg(cfg, rt);
  	if (err)
  		goto freert;
  
  	mpls_route_update(net, index, rt, &cfg->rc_nlinfo);

  	return 0;

  freert:
  	mpls_rt_free(rt);

  errout:

  	return err;
  }

  static int mpls_route_del(struct mpls_route_config *cfg,
  			  struct netlink_ext_ack *extack)

  {
  	struct net *net = cfg->rc_nlinfo.nl_net;
  	unsigned index;
  	int err = -EINVAL;
  
  	index = cfg->rc_label;

  	if (!mpls_label_ok(net, &index, extack))

  		goto errout;

  	mpls_route_update(net, index, NULL, &cfg->rc_nlinfo);

  
  	err = 0;
  errout:
  	return err;
  }

  static void mpls_get_stats(struct mpls_dev *mdev,
  			   struct mpls_link_stats *stats)
  {
  	struct mpls_pcpu_stats *p;
  	int i;
  
  	memset(stats, 0, sizeof(*stats));
  
  	for_each_possible_cpu(i) {
  		struct mpls_link_stats local;
  		unsigned int start;
  
  		p = per_cpu_ptr(mdev->stats, i);
  		do {
  			start = u64_stats_fetch_begin(&p->syncp);
  			local = p->stats;
  		} while (u64_stats_fetch_retry(&p->syncp, start));
  
  		stats->rx_packets	+= local.rx_packets;
  		stats->rx_bytes		+= local.rx_bytes;
  		stats->tx_packets	+= local.tx_packets;
  		stats->tx_bytes		+= local.tx_bytes;
  		stats->rx_errors	+= local.rx_errors;
  		stats->tx_errors	+= local.tx_errors;
  		stats->rx_dropped	+= local.rx_dropped;
  		stats->tx_dropped	+= local.tx_dropped;
  		stats->rx_noroute	+= local.rx_noroute;
  	}
  }
  
  static int mpls_fill_stats_af(struct sk_buff *skb,
  			      const struct net_device *dev)
  {
  	struct mpls_link_stats *stats;
  	struct mpls_dev *mdev;
  	struct nlattr *nla;
  
  	mdev = mpls_dev_get(dev);
  	if (!mdev)
  		return -ENODATA;
  
  	nla = nla_reserve_64bit(skb, MPLS_STATS_LINK,
  				sizeof(struct mpls_link_stats),
  				MPLS_STATS_UNSPEC);
  	if (!nla)
  		return -EMSGSIZE;
  
  	stats = nla_data(nla);
  	mpls_get_stats(mdev, stats);
  
  	return 0;
  }
  
  static size_t mpls_get_stats_af_size(const struct net_device *dev)
  {
  	struct mpls_dev *mdev;
  
  	mdev = mpls_dev_get(dev);
  	if (!mdev)
  		return 0;
  
  	return nla_total_size_64bit(sizeof(struct mpls_link_stats));
  }

  static int mpls_netconf_fill_devconf(struct sk_buff *skb, struct mpls_dev *mdev,
  				     u32 portid, u32 seq, int event,
  				     unsigned int flags, int type)
  {
  	struct nlmsghdr  *nlh;
  	struct netconfmsg *ncm;
  	bool all = false;
  
  	nlh = nlmsg_put(skb, portid, seq, event, sizeof(struct netconfmsg),
  			flags);
  	if (!nlh)
  		return -EMSGSIZE;
  
  	if (type == NETCONFA_ALL)
  		all = true;
  
  	ncm = nlmsg_data(nlh);
  	ncm->ncm_family = AF_MPLS;
  
  	if (nla_put_s32(skb, NETCONFA_IFINDEX, mdev->dev->ifindex) < 0)
  		goto nla_put_failure;
  
  	if ((all || type == NETCONFA_INPUT) &&
  	    nla_put_s32(skb, NETCONFA_INPUT,
  			mdev->input_enabled) < 0)
  		goto nla_put_failure;
  
  	nlmsg_end(skb, nlh);
  	return 0;
  
  nla_put_failure:
  	nlmsg_cancel(skb, nlh);
  	return -EMSGSIZE;
  }
  
  static int mpls_netconf_msgsize_devconf(int type)
  {
  	int size = NLMSG_ALIGN(sizeof(struct netconfmsg))
  			+ nla_total_size(4); /* NETCONFA_IFINDEX */
  	bool all = false;
  
  	if (type == NETCONFA_ALL)
  		all = true;
  
  	if (all || type == NETCONFA_INPUT)
  		size += nla_total_size(4);
  
  	return size;
  }

  static void mpls_netconf_notify_devconf(struct net *net, int event,
  					int type, struct mpls_dev *mdev)

  {
  	struct sk_buff *skb;
  	int err = -ENOBUFS;
  
  	skb = nlmsg_new(mpls_netconf_msgsize_devconf(type), GFP_KERNEL);
  	if (!skb)
  		goto errout;

  	err = mpls_netconf_fill_devconf(skb, mdev, 0, 0, event, 0, type);

  	if (err < 0) {
  		/* -EMSGSIZE implies BUG in mpls_netconf_msgsize_devconf() */
  		WARN_ON(err == -EMSGSIZE);
  		kfree_skb(skb);
  		goto errout;
  	}
  
  	rtnl_notify(skb, net, 0, RTNLGRP_MPLS_NETCONF, NULL, GFP_KERNEL);
  	return;
  errout:
  	if (err < 0)
  		rtnl_set_sk_err(net, RTNLGRP_MPLS_NETCONF, err);
  }
  
  static const struct nla_policy devconf_mpls_policy[NETCONFA_MAX + 1] = {
  	[NETCONFA_IFINDEX]	= { .len = sizeof(int) },
  };

  static int mpls_netconf_valid_get_req(struct sk_buff *skb,
  				      const struct nlmsghdr *nlh,
  				      struct nlattr **tb,
  				      struct netlink_ext_ack *extack)
  {
  	int i, err;
  
  	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(struct netconfmsg))) {
  		NL_SET_ERR_MSG_MOD(extack,
  				   "Invalid header for netconf get request");
  		return -EINVAL;
  	}
  
  	if (!netlink_strict_get_check(skb))

  		return nlmsg_parse_deprecated(nlh, sizeof(struct netconfmsg),
  					      tb, NETCONFA_MAX,
  					      devconf_mpls_policy, extack);

  	err = nlmsg_parse_deprecated_strict(nlh, sizeof(struct netconfmsg),
  					    tb, NETCONFA_MAX,
  					    devconf_mpls_policy, extack);

  	if (err)
  		return err;
  
  	for (i = 0; i <= NETCONFA_MAX; i++) {
  		if (!tb[i])
  			continue;
  
  		switch (i) {
  		case NETCONFA_IFINDEX:
  			break;
  		default:
  			NL_SET_ERR_MSG_MOD(extack, "Unsupported attribute in netconf get request");
  			return -EINVAL;
  		}
  	}
  
  	return 0;
  }

  static int mpls_netconf_get_devconf(struct sk_buff *in_skb,

  				    struct nlmsghdr *nlh,
  				    struct netlink_ext_ack *extack)

  {
  	struct net *net = sock_net(in_skb->sk);
  	struct nlattr *tb[NETCONFA_MAX + 1];

  	struct net_device *dev;
  	struct mpls_dev *mdev;
  	struct sk_buff *skb;
  	int ifindex;
  	int err;

  	err = mpls_netconf_valid_get_req(in_skb, nlh, tb, extack);

  	if (err < 0)
  		goto errout;
  
  	err = -EINVAL;
  	if (!tb[NETCONFA_IFINDEX])
  		goto errout;
  
  	ifindex = nla_get_s32(tb[NETCONFA_IFINDEX]);
  	dev = __dev_get_by_index(net, ifindex);
  	if (!dev)
  		goto errout;
  
  	mdev = mpls_dev_get(dev);
  	if (!mdev)
  		goto errout;
  
  	err = -ENOBUFS;
  	skb = nlmsg_new(mpls_netconf_msgsize_devconf(NETCONFA_ALL), GFP_KERNEL);
  	if (!skb)
  		goto errout;
  
  	err = mpls_netconf_fill_devconf(skb, mdev,
  					NETLINK_CB(in_skb).portid,
  					nlh->nlmsg_seq, RTM_NEWNETCONF, 0,
  					NETCONFA_ALL);
  	if (err < 0) {
  		/* -EMSGSIZE implies BUG in mpls_netconf_msgsize_devconf() */
  		WARN_ON(err == -EMSGSIZE);
  		kfree_skb(skb);
  		goto errout;
  	}
  	err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
  errout:
  	return err;
  }
  
  static int mpls_netconf_dump_devconf(struct sk_buff *skb,
  				     struct netlink_callback *cb)
  {

  	const struct nlmsghdr *nlh = cb->nlh;

  	struct net *net = sock_net(skb->sk);
  	struct hlist_head *head;
  	struct net_device *dev;
  	struct mpls_dev *mdev;
  	int idx, s_idx;
  	int h, s_h;

  	if (cb->strict_check) {
  		struct netlink_ext_ack *extack = cb->extack;
  		struct netconfmsg *ncm;
  
  		if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ncm))) {
  			NL_SET_ERR_MSG_MOD(extack, "Invalid header for netconf dump request");
  			return -EINVAL;
  		}
  
  		if (nlmsg_attrlen(nlh, sizeof(*ncm))) {
  			NL_SET_ERR_MSG_MOD(extack, "Invalid data after header in netconf dump request");
  			return -EINVAL;
  		}
  	}

  	s_h = cb->args[0];
  	s_idx = idx = cb->args[1];
  
  	for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
  		idx = 0;
  		head = &net->dev_index_head[h];
  		rcu_read_lock();
  		cb->seq = net->dev_base_seq;
  		hlist_for_each_entry_rcu(dev, head, index_hlist) {
  			if (idx < s_idx)
  				goto cont;
  			mdev = mpls_dev_get(dev);
  			if (!mdev)
  				goto cont;
  			if (mpls_netconf_fill_devconf(skb, mdev,
  						      NETLINK_CB(cb->skb).portid,

  						      nlh->nlmsg_seq,

  						      RTM_NEWNETCONF,
  						      NLM_F_MULTI,
  						      NETCONFA_ALL) < 0) {
  				rcu_read_unlock();
  				goto done;
  			}
  			nl_dump_check_consistent(cb, nlmsg_hdr(skb));
  cont:
  			idx++;
  		}
  		rcu_read_unlock();
  	}
  done:
  	cb->args[0] = h;
  	cb->args[1] = idx;
  
  	return skb->len;
  }

  #define MPLS_PERDEV_SYSCTL_OFFSET(field)	\
  	(&((struct mpls_dev *)0)->field)

  static int mpls_conf_proc(struct ctl_table *ctl, int write,

  			  void *buffer, size_t *lenp, loff_t *ppos)

  {
  	int oval = *(int *)ctl->data;
  	int ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
  
  	if (write) {
  		struct mpls_dev *mdev = ctl->extra1;
  		int i = (int *)ctl->data - (int *)mdev;
  		struct net *net = ctl->extra2;
  		int val = *(int *)ctl->data;
  
  		if (i == offsetof(struct mpls_dev, input_enabled) &&
  		    val != oval) {

  			mpls_netconf_notify_devconf(net, RTM_NEWNETCONF,
  						    NETCONFA_INPUT, mdev);

  		}
  	}
  
  	return ret;
  }

  static const struct ctl_table mpls_dev_table[] = {
  	{
  		.procname	= "input",
  		.maxlen		= sizeof(int),
  		.mode		= 0644,

  		.proc_handler	= mpls_conf_proc,

  		.data		= MPLS_PERDEV_SYSCTL_OFFSET(input_enabled),
  	},
  	{ }
  };
  
  static int mpls_dev_sysctl_register(struct net_device *dev,
  				    struct mpls_dev *mdev)
  {
  	char path[sizeof("net/mpls/conf/") + IFNAMSIZ];

  	struct net *net = dev_net(dev);

  	struct ctl_table *table;
  	int i;
  
  	table = kmemdup(&mpls_dev_table, sizeof(mpls_dev_table), GFP_KERNEL);
  	if (!table)
  		goto out;
  
  	/* Table data contains only offsets relative to the base of
  	 * the mdev at this point, so make them absolute.
  	 */

  	for (i = 0; i < ARRAY_SIZE(mpls_dev_table); i++) {

  		table[i].data = (char *)mdev + (uintptr_t)table[i].data;

  		table[i].extra1 = mdev;
  		table[i].extra2 = net;
  	}

  
  	snprintf(path, sizeof(path), "net/mpls/conf/%s", dev->name);

  	mdev->sysctl = register_net_sysctl(net, path, table);

  	if (!mdev->sysctl)
  		goto free;

  	mpls_netconf_notify_devconf(net, RTM_NEWNETCONF, NETCONFA_ALL, mdev);

  	return 0;
  
  free:
  	kfree(table);
  out:
  	return -ENOBUFS;
  }

  static void mpls_dev_sysctl_unregister(struct net_device *dev,
  				       struct mpls_dev *mdev)

  {

  	struct net *net = dev_net(dev);

  	struct ctl_table *table;
  
  	table = mdev->sysctl->ctl_table_arg;
  	unregister_net_sysctl_table(mdev->sysctl);
  	kfree(table);

  
  	mpls_netconf_notify_devconf(net, RTM_DELNETCONF, 0, mdev);

  }

  static struct mpls_dev *mpls_add_dev(struct net_device *dev)
  {
  	struct mpls_dev *mdev;
  	int err = -ENOMEM;

  	int i;

  
  	ASSERT_RTNL();
  
  	mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
  	if (!mdev)
  		return ERR_PTR(err);

  	mdev->stats = alloc_percpu(struct mpls_pcpu_stats);
  	if (!mdev->stats)
  		goto free;
  
  	for_each_possible_cpu(i) {
  		struct mpls_pcpu_stats *mpls_stats;
  
  		mpls_stats = per_cpu_ptr(mdev->stats, i);
  		u64_stats_init(&mpls_stats->syncp);
  	}

  	mdev->dev = dev;

  	err = mpls_dev_sysctl_register(dev, mdev);
  	if (err)
  		goto free;

  	rcu_assign_pointer(dev->mpls_ptr, mdev);
  
  	return mdev;

  
  free:

  	free_percpu(mdev->stats);

  	kfree(mdev);
  	return ERR_PTR(err);

  }

  static void mpls_dev_destroy_rcu(struct rcu_head *head)
  {
  	struct mpls_dev *mdev = container_of(head, struct mpls_dev, rcu);
  
  	free_percpu(mdev->stats);
  	kfree(mdev);
  }

  static void mpls_ifdown(struct net_device *dev, int event)

  {

  	struct mpls_route __rcu **platform_label;

  	struct net *net = dev_net(dev);

  	u8 alive, deleted;

  	unsigned index;

  	platform_label = rtnl_dereference(net->mpls.platform_label);

  	for (index = 0; index < net->mpls.platform_labels; index++) {

  		struct mpls_route *rt = rtnl_dereference(platform_label[index]);

  		if (!rt)
  			continue;

  		alive = 0;

  		deleted = 0;

  		change_nexthops(rt) {

  			unsigned int nh_flags = nh->nh_flags;

  			if (rtnl_dereference(nh->nh_dev) != dev)

  				goto next;

  			switch (event) {
  			case NETDEV_DOWN:
  			case NETDEV_UNREGISTER:

  				nh_flags |= RTNH_F_DEAD;

  				/* fall through */
  			case NETDEV_CHANGE:

  				nh_flags |= RTNH_F_LINKDOWN;

  				break;
  			}
  			if (event == NETDEV_UNREGISTER)
  				RCU_INIT_POINTER(nh->nh_dev, NULL);

  
  			if (nh->nh_flags != nh_flags)
  				WRITE_ONCE(nh->nh_flags, nh_flags);

  next:

  			if (!(nh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)))

  				alive++;

  			if (!rtnl_dereference(nh->nh_dev))
  				deleted++;

  		} endfor_nexthops(rt);

  
  		WRITE_ONCE(rt->rt_nhn_alive, alive);

  
  		/* if there are no more nexthops, delete the route */
  		if (event == NETDEV_UNREGISTER && deleted == rt->rt_nhn)
  			mpls_route_update(net, index, NULL, NULL);

  	}

  }

  static void mpls_ifup(struct net_device *dev, unsigned int flags)

  {
  	struct mpls_route __rcu **platform_label;
  	struct net *net = dev_net(dev);
  	unsigned index;

  	u8 alive;

  
  	platform_label = rtnl_dereference(net->mpls.platform_label);
  	for (index = 0; index < net->mpls.platform_labels; index++) {
  		struct mpls_route *rt = rtnl_dereference(platform_label[index]);
  
  		if (!rt)
  			continue;

  		alive = 0;
  		change_nexthops(rt) {

  			unsigned int nh_flags = nh->nh_flags;

  			struct net_device *nh_dev =
  				rtnl_dereference(nh->nh_dev);

  			if (!(nh_flags & flags)) {

  				alive++;
  				continue;
  			}
  			if (nh_dev != dev)
  				continue;
  			alive++;

  			nh_flags &= ~flags;

  			WRITE_ONCE(nh->nh_flags, nh_flags);

  		} endfor_nexthops(rt);

  		WRITE_ONCE(rt->rt_nhn_alive, alive);

  	}

  }
  
  static int mpls_dev_notify(struct notifier_block *this, unsigned long event,
  			   void *ptr)
  {
  	struct net_device *dev = netdev_notifier_info_to_dev(ptr);

  	struct mpls_dev *mdev;

  	unsigned int flags;

  	if (event == NETDEV_REGISTER) {

  		mdev = mpls_add_dev(dev);
  		if (IS_ERR(mdev))
  			return notifier_from_errno(PTR_ERR(mdev));

  		return NOTIFY_OK;
  	}

  	mdev = mpls_dev_get(dev);
  	if (!mdev)
  		return NOTIFY_OK;
  
  	switch (event) {
  	case NETDEV_DOWN:
  		mpls_ifdown(dev, event);
  		break;
  	case NETDEV_UP:
  		flags = dev_get_flags(dev);
  		if (flags & (IFF_RUNNING | IFF_LOWER_UP))
  			mpls_ifup(dev, RTNH_F_DEAD | RTNH_F_LINKDOWN);
  		else
  			mpls_ifup(dev, RTNH_F_DEAD);
  		break;
  	case NETDEV_CHANGE:
  		flags = dev_get_flags(dev);
  		if (flags & (IFF_RUNNING | IFF_LOWER_UP))
  			mpls_ifup(dev, RTNH_F_DEAD | RTNH_F_LINKDOWN);
  		else
  			mpls_ifdown(dev, event);
  		break;

  	case NETDEV_UNREGISTER:

  		mpls_ifdown(dev, event);
  		mdev = mpls_dev_get(dev);
  		if (mdev) {

  			mpls_dev_sysctl_unregister(dev, mdev);

  			RCU_INIT_POINTER(dev->mpls_ptr, NULL);

  			call_rcu(&mdev->rcu, mpls_dev_destroy_rcu);

  		}

  		break;

  	case NETDEV_CHANGENAME:
  		mdev = mpls_dev_get(dev);
  		if (mdev) {
  			int err;

  			mpls_dev_sysctl_unregister(dev, mdev);

  			err = mpls_dev_sysctl_register(dev, mdev);
  			if (err)
  				return notifier_from_errno(err);
  		}
  		break;

  	}
  	return NOTIFY_OK;
  }
  
  static struct notifier_block mpls_dev_notifier = {
  	.notifier_call = mpls_dev_notify,
  };

  static int nla_put_via(struct sk_buff *skb,

  		       u8 table, const void *addr, int alen)

  {

  	static const int table_to_family[NEIGH_NR_TABLES + 1] = {
  		AF_INET, AF_INET6, AF_DECnet, AF_PACKET,
  	};

  	struct nlattr *nla;
  	struct rtvia *via;

  	int family = AF_UNSPEC;

  
  	nla = nla_reserve(skb, RTA_VIA, alen + 2);
  	if (!nla)
  		return -EMSGSIZE;

  	if (table <= NEIGH_NR_TABLES)
  		family = table_to_family[table];

  	via = nla_data(nla);
  	via->rtvia_family = family;
  	memcpy(via->rtvia_addr, addr, alen);
  	return 0;
  }

  int nla_put_labels(struct sk_buff *skb, int attrtype,
  		   u8 labels, const u32 label[])
  {
  	struct nlattr *nla;
  	struct mpls_shim_hdr *nla_label;
  	bool bos;
  	int i;
  	nla = nla_reserve(skb, attrtype, labels*4);
  	if (!nla)
  		return -EMSGSIZE;
  
  	nla_label = nla_data(nla);
  	bos = true;
  	for (i = labels - 1; i >= 0; i--) {
  		nla_label[i] = mpls_entry_encode(label[i], 0, 0, bos);
  		bos = false;
  	}
  
  	return 0;
  }

  EXPORT_SYMBOL_GPL(nla_put_labels);

  int nla_get_labels(const struct nlattr *nla, u8 max_labels, u8 *labels,
  		   u32 label[], struct netlink_ext_ack *extack)

  {
  	unsigned len = nla_len(nla);

  	struct mpls_shim_hdr *nla_label;

  	u8 nla_labels;

  	bool bos;
  	int i;

  	/* len needs to be an even multiple of 4 (the label size). Number
  	 * of labels is a u8 so check for overflow.
  	 */

  	if (len & 3 || len / 4 > 255) {
  		NL_SET_ERR_MSG_ATTR(extack, nla,
  				    "Invalid length for labels attribute");

  		return -EINVAL;

  	}

  
  	/* Limit the number of new labels allowed */
  	nla_labels = len/4;

  	if (nla_labels > max_labels) {
  		NL_SET_ERR_MSG(extack, "Too many labels");

  		return -EINVAL;

  	}

  	/* when label == NULL, caller wants number of labels */
  	if (!label)
  		goto out;

  	nla_label = nla_data(nla);
  	bos = true;
  	for (i = nla_labels - 1; i >= 0; i--, bos = false) {
  		struct mpls_entry_decoded dec;
  		dec = mpls_entry_decode(nla_label + i);
  
  		/* Ensure the bottom of stack flag is properly set
  		 * and ttl and tc are both clear.
  		 */

  		if (dec.ttl) {
  			NL_SET_ERR_MSG_ATTR(extack, nla,
  					    "TTL in label must be 0");
  			return -EINVAL;
  		}
  
  		if (dec.tc) {
  			NL_SET_ERR_MSG_ATTR(extack, nla,
  					    "Traffic class in label must be 0");

  			return -EINVAL;

  		}
  
  		if (dec.bos != bos) {
  			NL_SET_BAD_ATTR(extack, nla);
  			if (bos) {
  				NL_SET_ERR_MSG(extack,
  					       "BOS bit must be set in first label");
  			} else {
  				NL_SET_ERR_MSG(extack,
  					       "BOS bit can only be set in first label");
  			}
  			return -EINVAL;
  		}

  		switch (dec.label) {

  		case MPLS_LABEL_IMPLNULL:

  			/* RFC3032: This is a label that an LSR may
  			 * assign and distribute, but which never
  			 * actually appears in the encapsulation.
  			 */

  			NL_SET_ERR_MSG_ATTR(extack, nla,
  					    "Implicit NULL Label (3) can not be used in encapsulation");

  			return -EINVAL;
  		}

  		label[i] = dec.label;
  	}

  out:

  	*labels = nla_labels;
  	return 0;
  }

  EXPORT_SYMBOL_GPL(nla_get_labels);

  static int rtm_to_route_config(struct sk_buff *skb,
  			       struct nlmsghdr *nlh,
  			       struct mpls_route_config *cfg,
  			       struct netlink_ext_ack *extack)

  {
  	struct rtmsg *rtm;
  	struct nlattr *tb[RTA_MAX+1];
  	int index;
  	int err;

  	err = nlmsg_parse_deprecated(nlh, sizeof(*rtm), tb, RTA_MAX,
  				     rtm_mpls_policy, extack);

  	if (err < 0)
  		goto errout;
  
  	err = -EINVAL;
  	rtm = nlmsg_data(nlh);

  	if (rtm->rtm_family != AF_MPLS) {
  		NL_SET_ERR_MSG(extack, "Invalid address family in rtmsg");

  		goto errout;

  	}
  	if (rtm->rtm_dst_len != 20) {
  		NL_SET_ERR_MSG(extack, "rtm_dst_len must be 20 for MPLS");

  		goto errout;

  	}
  	if (rtm->rtm_src_len != 0) {
  		NL_SET_ERR_MSG(extack, "rtm_src_len must be 0 for MPLS");

  		goto errout;

  	}
  	if (rtm->rtm_tos != 0) {
  		NL_SET_ERR_MSG(extack, "rtm_tos must be 0 for MPLS");

  		goto errout;

  	}
  	if (rtm->rtm_table != RT_TABLE_MAIN) {
  		NL_SET_ERR_MSG(extack,
  			       "MPLS only supports the main route table");

  		goto errout;

  	}

  	/* Any value is acceptable for rtm_protocol */
  
  	/* As mpls uses destination specific addresses
  	 * (or source specific address in the case of multicast)
  	 * all addresses have universal scope.
  	 */

  	if (rtm->rtm_scope != RT_SCOPE_UNIVERSE) {
  		NL_SET_ERR_MSG(extack,
  			       "Invalid route scope  - MPLS only supports UNIVERSE");

  		goto errout;

  	}
  	if (rtm->rtm_type != RTN_UNICAST) {
  		NL_SET_ERR_MSG(extack,
  			       "Invalid route type - MPLS only supports UNICAST");

  		goto errout;

  	}
  	if (rtm->rtm_flags != 0) {
  		NL_SET_ERR_MSG(extack, "rtm_flags must be 0 for MPLS");

  		goto errout;

  	}

  
  	cfg->rc_label		= LABEL_NOT_SPECIFIED;
  	cfg->rc_protocol	= rtm->rtm_protocol;

  	cfg->rc_via_table	= MPLS_NEIGH_TABLE_UNSPEC;

  	cfg->rc_ttl_propagate	= MPLS_TTL_PROP_DEFAULT;

  	cfg->rc_nlflags		= nlh->nlmsg_flags;
  	cfg->rc_nlinfo.portid	= NETLINK_CB(skb).portid;
  	cfg->rc_nlinfo.nlh	= nlh;
  	cfg->rc_nlinfo.nl_net	= sock_net(skb->sk);
  
  	for (index = 0; index <= RTA_MAX; index++) {
  		struct nlattr *nla = tb[index];
  		if (!nla)
  			continue;

  		switch (index) {

  		case RTA_OIF:
  			cfg->rc_ifindex = nla_get_u32(nla);
  			break;
  		case RTA_NEWDST:
  			if (nla_get_labels(nla, MAX_NEW_LABELS,
  					   &cfg->rc_output_labels,

  					   cfg->rc_output_label, extack))

  				goto errout;
  			break;
  		case RTA_DST:
  		{

  			u8 label_count;

  			if (nla_get_labels(nla, 1, &label_count,

  					   &cfg->rc_label, extack))

  				goto errout;

  			if (!mpls_label_ok(cfg->rc_nlinfo.nl_net,

  					   &cfg->rc_label, extack))

  				goto errout;

  			break;
  		}

  		case RTA_GATEWAY:
  			NL_SET_ERR_MSG(extack, "MPLS does not support RTA_GATEWAY attribute");
  			goto errout;

  		case RTA_VIA:
  		{

  			if (nla_get_via(nla, &cfg->rc_via_alen,

  					&cfg->rc_via_table, cfg->rc_via,
  					extack))

  				goto errout;

  			break;
  		}
  		case RTA_MULTIPATH:
  		{
  			cfg->rc_mp = nla_data(nla);
  			cfg->rc_mp_len = nla_len(nla);

  			break;
  		}

  		case RTA_TTL_PROPAGATE:
  		{
  			u8 ttl_propagate = nla_get_u8(nla);

  			if (ttl_propagate > 1) {
  				NL_SET_ERR_MSG_ATTR(extack, nla,
  						    "RTA_TTL_PROPAGATE can only be 0 or 1");

  				goto errout;

  			}

  			cfg->rc_ttl_propagate = ttl_propagate ?
  				MPLS_TTL_PROP_ENABLED :
  				MPLS_TTL_PROP_DISABLED;
  			break;
  		}

  		default:

  			NL_SET_ERR_MSG_ATTR(extack, nla, "Unknown attribute");

  			/* Unsupported attribute */
  			goto errout;
  		}
  	}
  
  	err = 0;
  errout:
  	return err;
  }

  static int mpls_rtm_delroute(struct sk_buff *skb, struct nlmsghdr *nlh,
  			     struct netlink_ext_ack *extack)

  {

  	struct mpls_route_config *cfg;

  	int err;

  	cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
  	if (!cfg)
  		return -ENOMEM;

  	err = rtm_to_route_config(skb, nlh, cfg, extack);

  	if (err < 0)

  		goto out;

  	err = mpls_route_del(cfg, extack);

  out:
  	kfree(cfg);
  
  	return err;

  }

  static int mpls_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh,
  			     struct netlink_ext_ack *extack)

  {

  	struct mpls_route_config *cfg;

  	int err;

  	cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
  	if (!cfg)
  		return -ENOMEM;

  	err = rtm_to_route_config(skb, nlh, cfg, extack);

  	if (err < 0)

  		goto out;

  	err = mpls_route_add(cfg, extack);

  out:
  	kfree(cfg);
  
  	return err;

  }
  
  static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event,
  			   u32 label, struct mpls_route *rt, int flags)
  {

  	struct net_device *dev;

  	struct nlmsghdr *nlh;
  	struct rtmsg *rtm;
  
  	nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
  	if (nlh == NULL)
  		return -EMSGSIZE;
  
  	rtm = nlmsg_data(nlh);
  	rtm->rtm_family = AF_MPLS;
  	rtm->rtm_dst_len = 20;
  	rtm->rtm_src_len = 0;
  	rtm->rtm_tos = 0;
  	rtm->rtm_table = RT_TABLE_MAIN;
  	rtm->rtm_protocol = rt->rt_protocol;
  	rtm->rtm_scope = RT_SCOPE_UNIVERSE;
  	rtm->rtm_type = RTN_UNICAST;
  	rtm->rtm_flags = 0;

  	if (nla_put_labels(skb, RTA_DST, 1, &label))
  		goto nla_put_failure;

  
  	if (rt->rt_ttl_propagate != MPLS_TTL_PROP_DEFAULT) {
  		bool ttl_propagate =
  			rt->rt_ttl_propagate == MPLS_TTL_PROP_ENABLED;
  
  		if (nla_put_u8(skb, RTA_TTL_PROPAGATE,
  			       ttl_propagate))
  			goto nla_put_failure;
  	}

  	if (rt->rt_nhn == 1) {

  		const struct mpls_nh *nh = rt->rt_nh;

  
  		if (nh->nh_labels &&
  		    nla_put_labels(skb, RTA_NEWDST, nh->nh_labels,
  				   nh->nh_label))
  			goto nla_put_failure;

  		if (nh->nh_via_table != MPLS_NEIGH_TABLE_UNSPEC &&

  		    nla_put_via(skb, nh->nh_via_table, mpls_nh_via(rt, nh),

  				nh->nh_via_alen))
  			goto nla_put_failure;
  		dev = rtnl_dereference(nh->nh_dev);
  		if (dev && nla_put_u32(skb, RTA_OIF, dev->ifindex))
  			goto nla_put_failure;

  		if (nh->nh_flags & RTNH_F_LINKDOWN)
  			rtm->rtm_flags |= RTNH_F_LINKDOWN;
  		if (nh->nh_flags & RTNH_F_DEAD)
  			rtm->rtm_flags |= RTNH_F_DEAD;

  	} else {
  		struct rtnexthop *rtnh;
  		struct nlattr *mp;

  		u8 linkdown = 0;
  		u8 dead = 0;

  		mp = nla_nest_start_noflag(skb, RTA_MULTIPATH);

  		if (!mp)
  			goto nla_put_failure;
  
  		for_nexthops(rt) {

  			dev = rtnl_dereference(nh->nh_dev);
  			if (!dev)
  				continue;

  			rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
  			if (!rtnh)
  				goto nla_put_failure;

  			rtnh->rtnh_ifindex = dev->ifindex;

  			if (nh->nh_flags & RTNH_F_LINKDOWN) {
  				rtnh->rtnh_flags |= RTNH_F_LINKDOWN;
  				linkdown++;
  			}
  			if (nh->nh_flags & RTNH_F_DEAD) {
  				rtnh->rtnh_flags |= RTNH_F_DEAD;
  				dead++;
  			}

  			if (nh->nh_labels && nla_put_labels(skb, RTA_NEWDST,
  							    nh->nh_labels,
  							    nh->nh_label))
  				goto nla_put_failure;

  			if (nh->nh_via_table != MPLS_NEIGH_TABLE_UNSPEC &&
  			    nla_put_via(skb, nh->nh_via_table,

  					mpls_nh_via(rt, nh),

  					nh->nh_via_alen))
  				goto nla_put_failure;
  
  			/* length of rtnetlink header + attributes */
  			rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *)rtnh;
  		} endfor_nexthops(rt);

  		if (linkdown == rt->rt_nhn)
  			rtm->rtm_flags |= RTNH_F_LINKDOWN;
  		if (dead == rt->rt_nhn)
  			rtm->rtm_flags |= RTNH_F_DEAD;

  		nla_nest_end(skb, mp);
  	}

  
  	nlmsg_end(skb, nlh);
  	return 0;
  
  nla_put_failure:
  	nlmsg_cancel(skb, nlh);
  	return -EMSGSIZE;
  }

  #if IS_ENABLED(CONFIG_INET)

  static int mpls_valid_fib_dump_req(struct net *net, const struct nlmsghdr *nlh,
  				   struct fib_dump_filter *filter,

  				   struct netlink_callback *cb)

  {