net/tipc/udp_media.c

/* net/tipc/udp_media.c: IP bearer support for TIPC
 *
 * Copyright (c) 2015, Ericsson AB
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the names of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <linux/socket.h>
#include <linux/ip.h>
#include <linux/udp.h>
#include <linux/inet.h>
#include <linux/inetdevice.h>
#include <linux/igmp.h>
#include <linux/kernel.h>
#include <linux/workqueue.h>
#include <linux/list.h>
#include <net/sock.h>
#include <net/ip.h>
#include <net/udp_tunnel.h>
#include <net/ipv6_stubs.h>
#include <linux/tipc_netlink.h>
#include "core.h"
#include "addr.h"
#include "net.h"
#include "bearer.h"
#include "netlink.h"
#include "msg.h"

/* IANA assigned UDP port */
#define UDP_PORT_DEFAULT	6118

#define UDP_MIN_HEADROOM        48

/**
 * struct udp_media_addr - IP/UDP addressing information
 *
 * This is the bearer level originating address used in neighbor discovery
 * messages, and all fields should be in network byte order
 */
struct udp_media_addr {
	__be16	proto;
	__be16	port;
	union {
		struct in_addr ipv4;
		struct in6_addr ipv6;
	};
};

/* struct udp_replicast - container for UDP remote addresses */
struct udp_replicast {
	struct udp_media_addr addr;
	struct dst_cache dst_cache;
	struct rcu_head rcu;
	struct list_head list;
};

/**
 * struct udp_bearer - ip/udp bearer data structure
 * @bearer:	associated generic tipc bearer
 * @ubsock:	bearer associated socket
 * @ifindex:	local address scope
 * @work:	used to schedule deferred work on a bearer
 */
struct udp_bearer {
	struct tipc_bearer __rcu *bearer;
	struct socket *ubsock;
	u32 ifindex;
	struct work_struct work;
	struct udp_replicast rcast;
};

static int tipc_udp_is_mcast_addr(struct udp_media_addr *addr)
{
	if (ntohs(addr->proto) == ETH_P_IP)
		return ipv4_is_multicast(addr->ipv4.s_addr);
#if IS_ENABLED(CONFIG_IPV6)
	else
		return ipv6_addr_is_multicast(&addr->ipv6);
#endif
	return 0;
}

/* udp_media_addr_set - convert a ip/udp address to a TIPC media address */
static void tipc_udp_media_addr_set(struct tipc_media_addr *addr,
				    struct udp_media_addr *ua)
{
	memset(addr, 0, sizeof(struct tipc_media_addr));
	addr->media_id = TIPC_MEDIA_TYPE_UDP;
	memcpy(addr->value, ua, sizeof(struct udp_media_addr));

	if (tipc_udp_is_mcast_addr(ua))
		addr->broadcast = TIPC_BROADCAST_SUPPORT;
}

/* tipc_udp_addr2str - convert ip/udp address to string */
static int tipc_udp_addr2str(struct tipc_media_addr *a, char *buf, int size)
{
	struct udp_media_addr *ua = (struct udp_media_addr *)&a->value;

	if (ntohs(ua->proto) == ETH_P_IP)
		snprintf(buf, size, "%pI4:%u", &ua->ipv4, ntohs(ua->port));
	else if (ntohs(ua->proto) == ETH_P_IPV6)
		snprintf(buf, size, "%pI6:%u", &ua->ipv6, ntohs(ua->port));
	else
		pr_err("Invalid UDP media address\n");
	return 0;
}

/* tipc_udp_msg2addr - extract an ip/udp address from a TIPC ndisc message */
static int tipc_udp_msg2addr(struct tipc_bearer *b, struct tipc_media_addr *a,
			     char *msg)
{
	struct udp_media_addr *ua;

	ua = (struct udp_media_addr *) (msg + TIPC_MEDIA_ADDR_OFFSET);
	if (msg[TIPC_MEDIA_TYPE_OFFSET] != TIPC_MEDIA_TYPE_UDP)
		return -EINVAL;
	tipc_udp_media_addr_set(a, ua);
	return 0;
}

/* tipc_udp_addr2msg - write an ip/udp address to a TIPC ndisc message */
static int tipc_udp_addr2msg(char *msg, struct tipc_media_addr *a)
{
	memset(msg, 0, TIPC_MEDIA_INFO_SIZE);
	msg[TIPC_MEDIA_TYPE_OFFSET] = TIPC_MEDIA_TYPE_UDP;
	memcpy(msg + TIPC_MEDIA_ADDR_OFFSET, a->value,
	       sizeof(struct udp_media_addr));
	return 0;
}

/* tipc_send_msg - enqueue a send request */
static int tipc_udp_xmit(struct net *net, struct sk_buff *skb,
			 struct udp_bearer *ub, struct udp_media_addr *src,
			 struct udp_media_addr *dst, struct dst_cache *cache)
{
	struct dst_entry *ndst = dst_cache_get(cache);
	int ttl, err = 0;

	if (dst->proto == htons(ETH_P_IP)) {
		struct rtable *rt = (struct rtable *)ndst;

		if (!rt) {
			struct flowi4 fl = {
				.daddr = dst->ipv4.s_addr,
				.saddr = src->ipv4.s_addr,
				.flowi4_mark = skb->mark,
				.flowi4_proto = IPPROTO_UDP
			};
			rt = ip_route_output_key(net, &fl);
			if (IS_ERR(rt)) {
				err = PTR_ERR(rt);
				goto tx_error;
			}
			dst_cache_set_ip4(cache, &rt->dst, fl.saddr);
		}

		ttl = ip4_dst_hoplimit(&rt->dst);
		udp_tunnel_xmit_skb(rt, ub->ubsock->sk, skb, src->ipv4.s_addr,
				    dst->ipv4.s_addr, 0, ttl, 0, src->port,
				    dst->port, false, true);
#if IS_ENABLED(CONFIG_IPV6)
	} else {
		if (!ndst) {
			struct flowi6 fl6 = {
				.flowi6_oif = ub->ifindex,
				.daddr = dst->ipv6,
				.saddr = src->ipv6,
				.flowi6_proto = IPPROTO_UDP
			};
			err = ipv6_stub->ipv6_dst_lookup(net, ub->ubsock->sk,
							 &ndst, &fl6);
			if (err)
				goto tx_error;
			dst_cache_set_ip6(cache, ndst, &fl6.saddr);
		}
		ttl = ip6_dst_hoplimit(ndst);
		err = udp_tunnel6_xmit_skb(ndst, ub->ubsock->sk, skb, NULL,
					   &src->ipv6, &dst->ipv6, 0, ttl, 0,
					   src->port, dst->port, false);
#endif
	}
	return err;

tx_error:
	kfree_skb(skb);
	return err;
}

static int tipc_udp_send_msg(struct net *net, struct sk_buff *skb,
			     struct tipc_bearer *b,
			     struct tipc_media_addr *addr)
{
	struct udp_media_addr *src = (struct udp_media_addr *)&b->addr.value;
	struct udp_media_addr *dst = (struct udp_media_addr *)&addr->value;
	struct udp_replicast *rcast;
	struct udp_bearer *ub;
	int err = 0;

	if (skb_headroom(skb) < UDP_MIN_HEADROOM) {
		err = pskb_expand_head(skb, UDP_MIN_HEADROOM, 0, GFP_ATOMIC);
		if (err)
			goto out;
	}

	skb_set_inner_protocol(skb, htons(ETH_P_TIPC));
	ub = rcu_dereference(b->media_ptr);
	if (!ub) {
		err = -ENODEV;
		goto out;
	}

	if (addr->broadcast != TIPC_REPLICAST_SUPPORT)
		return tipc_udp_xmit(net, skb, ub, src, dst,
				     &ub->rcast.dst_cache);

	/* Replicast, send an skb to each configured IP address */
	list_for_each_entry_rcu(rcast, &ub->rcast.list, list) {
		struct sk_buff *_skb;

		_skb = pskb_copy(skb, GFP_ATOMIC);
		if (!_skb) {
			err = -ENOMEM;
			goto out;
		}

		err = tipc_udp_xmit(net, _skb, ub, src, &rcast->addr,
				    &rcast->dst_cache);
		if (err)
			goto out;
	}
	err = 0;
out:
	kfree_skb(skb);
	return err;
}

static bool tipc_udp_is_known_peer(struct tipc_bearer *b,
				   struct udp_media_addr *addr)
{
	struct udp_replicast *rcast, *tmp;
	struct udp_bearer *ub;

	ub = rcu_dereference_rtnl(b->media_ptr);
	if (!ub) {
		pr_err_ratelimited("UDP bearer instance not found\n");
		return false;
	}

	list_for_each_entry_safe(rcast, tmp, &ub->rcast.list, list) {
		if (!memcmp(&rcast->addr, addr, sizeof(struct udp_media_addr)))
			return true;
	}

	return false;
}

static int tipc_udp_rcast_add(struct tipc_bearer *b,
			      struct udp_media_addr *addr)
{
	struct udp_replicast *rcast;
	struct udp_bearer *ub;

	ub = rcu_dereference_rtnl(b->media_ptr);
	if (!ub)
		return -ENODEV;

	rcast = kmalloc(sizeof(*rcast), GFP_ATOMIC);
	if (!rcast)
		return -ENOMEM;

	if (dst_cache_init(&rcast->dst_cache, GFP_ATOMIC)) {
		kfree(rcast);
		return -ENOMEM;
	}

	memcpy(&rcast->addr, addr, sizeof(struct udp_media_addr));

	if (ntohs(addr->proto) == ETH_P_IP)
		pr_info("New replicast peer: %pI4\n", &rcast->addr.ipv4);
#if IS_ENABLED(CONFIG_IPV6)
	else if (ntohs(addr->proto) == ETH_P_IPV6)
		pr_info("New replicast peer: %pI6\n", &rcast->addr.ipv6);
#endif
	b->bcast_addr.broadcast = TIPC_REPLICAST_SUPPORT;
	list_add_rcu(&rcast->list, &ub->rcast.list);
	return 0;
}

static int tipc_udp_rcast_disc(struct tipc_bearer *b, struct sk_buff *skb)
{
	struct udp_media_addr src = {0};
	struct udp_media_addr *dst;

	dst = (struct udp_media_addr *)&b->bcast_addr.value;
	if (tipc_udp_is_mcast_addr(dst))
		return 0;

	src.port = udp_hdr(skb)->source;

	if (ip_hdr(skb)->version == 4) {
		struct iphdr *iphdr = ip_hdr(skb);

		src.proto = htons(ETH_P_IP);
		src.ipv4.s_addr = iphdr->saddr;
		if (ipv4_is_multicast(iphdr->daddr))
			return 0;
#if IS_ENABLED(CONFIG_IPV6)
	} else if (ip_hdr(skb)->version == 6) {
		struct ipv6hdr *iphdr = ipv6_hdr(skb);

		src.proto = htons(ETH_P_IPV6);
		src.ipv6 = iphdr->saddr;
		if (ipv6_addr_is_multicast(&iphdr->daddr))
			return 0;
#endif
	} else {
		return 0;
	}

	if (likely(tipc_udp_is_known_peer(b, &src)))
		return 0;

	return tipc_udp_rcast_add(b, &src);
}

/* tipc_udp_recv - read data from bearer socket */
static int tipc_udp_recv(struct sock *sk, struct sk_buff *skb)
{
	struct udp_bearer *ub;
	struct tipc_bearer *b;
	struct tipc_msg *hdr;
	int err;

	ub = rcu_dereference_sk_user_data(sk);
	if (!ub) {
		pr_err_ratelimited("Failed to get UDP bearer reference");
		goto out;
	}
	skb_pull(skb, sizeof(struct udphdr));
	hdr = buf_msg(skb);

	b = rcu_dereference(ub->bearer);
	if (!b)
		goto out;

	if (b && test_bit(0, &b->up)) {
		tipc_rcv(sock_net(sk), skb, b);
		return 0;
	}

	if (unlikely(msg_user(hdr) == LINK_CONFIG)) {
		err = tipc_udp_rcast_disc(b, skb);
		if (err)
			goto out;
	}

out:
	kfree_skb(skb);
	return 0;
}

static int enable_mcast(struct udp_bearer *ub, struct udp_media_addr *remote)
{
	int err = 0;
	struct ip_mreqn mreqn;
	struct sock *sk = ub->ubsock->sk;

	if (ntohs(remote->proto) == ETH_P_IP) {
		mreqn.imr_multiaddr = remote->ipv4;
		mreqn.imr_ifindex = ub->ifindex;
		err = ip_mc_join_group(sk, &mreqn);
#if IS_ENABLED(CONFIG_IPV6)
	} else {
		err = ipv6_stub->ipv6_sock_mc_join(sk, ub->ifindex,
						   &remote->ipv6);
#endif
	}
	return err;
}

static int __tipc_nl_add_udp_addr(struct sk_buff *skb,
				  struct udp_media_addr *addr, int nla_t)
{
	if (ntohs(addr->proto) == ETH_P_IP) {
		struct sockaddr_in ip4;

		memset(&ip4, 0, sizeof(ip4));
		ip4.sin_family = AF_INET;
		ip4.sin_port = addr->port;
		ip4.sin_addr.s_addr = addr->ipv4.s_addr;
		if (nla_put(skb, nla_t, sizeof(ip4), &ip4))
			return -EMSGSIZE;

#if IS_ENABLED(CONFIG_IPV6)
	} else if (ntohs(addr->proto) == ETH_P_IPV6) {
		struct sockaddr_in6 ip6;

		memset(&ip6, 0, sizeof(ip6));
		ip6.sin6_family = AF_INET6;
		ip6.sin6_port  = addr->port;
		memcpy(&ip6.sin6_addr, &addr->ipv6, sizeof(struct in6_addr));
		if (nla_put(skb, nla_t, sizeof(ip6), &ip6))
			return -EMSGSIZE;
#endif
	}

	return 0;
}

int tipc_udp_nl_dump_remoteip(struct sk_buff *skb, struct netlink_callback *cb)
{
	u32 bid = cb->args[0];
	u32 skip_cnt = cb->args[1];
	u32 portid = NETLINK_CB(cb->skb).portid;
	struct udp_replicast *rcast, *tmp;
	struct tipc_bearer *b;
	struct udp_bearer *ub;
	void *hdr;
	int err;
	int i;

	if (!bid && !skip_cnt) {
		struct nlattr **attrs = genl_dumpit_info(cb)->attrs;
		struct net *net = sock_net(skb->sk);
		struct nlattr *battrs[TIPC_NLA_BEARER_MAX + 1];
		char *bname;

		if (!attrs[TIPC_NLA_BEARER])
			return -EINVAL;

		err = nla_parse_nested_deprecated(battrs, TIPC_NLA_BEARER_MAX,
						  attrs[TIPC_NLA_BEARER],
						  tipc_nl_bearer_policy, NULL);
		if (err)
			return err;

		if (!battrs[TIPC_NLA_BEARER_NAME])
			return -EINVAL;

		bname = nla_data(battrs[TIPC_NLA_BEARER_NAME]);

		rtnl_lock();
		b = tipc_bearer_find(net, bname);
		if (!b) {
			rtnl_unlock();
			return -EINVAL;
		}
		bid = b->identity;
	} else {
		struct net *net = sock_net(skb->sk);
		struct tipc_net *tn = net_generic(net, tipc_net_id);

		rtnl_lock();
		b = rtnl_dereference(tn->bearer_list[bid]);
		if (!b) {
			rtnl_unlock();
			return -EINVAL;
		}
	}

	ub = rtnl_dereference(b->media_ptr);
	if (!ub) {
		rtnl_unlock();
		return -EINVAL;
	}

	i = 0;
	list_for_each_entry_safe(rcast, tmp, &ub->rcast.list, list) {
		if (i < skip_cnt)
			goto count;

		hdr = genlmsg_put(skb, portid, cb->nlh->nlmsg_seq,
				  &tipc_genl_family, NLM_F_MULTI,
				  TIPC_NL_BEARER_GET);
		if (!hdr)
			goto done;

		err = __tipc_nl_add_udp_addr(skb, &rcast->addr,
					     TIPC_NLA_UDP_REMOTE);
		if (err) {
			genlmsg_cancel(skb, hdr);
			goto done;
		}
		genlmsg_end(skb, hdr);
count:
		i++;
	}
done:
	rtnl_unlock();
	cb->args[0] = bid;
	cb->args[1] = i;

	return skb->len;
}

int tipc_udp_nl_add_bearer_data(struct tipc_nl_msg *msg, struct tipc_bearer *b)
{
	struct udp_media_addr *src = (struct udp_media_addr *)&b->addr.value;
	struct udp_media_addr *dst;
	struct udp_bearer *ub;
	struct nlattr *nest;

	ub = rtnl_dereference(b->media_ptr);
	if (!ub)
		return -ENODEV;

	nest = nla_nest_start_noflag(msg->skb, TIPC_NLA_BEARER_UDP_OPTS);
	if (!nest)
		goto msg_full;

	if (__tipc_nl_add_udp_addr(msg->skb, src, TIPC_NLA_UDP_LOCAL))
		goto msg_full;

	dst = (struct udp_media_addr *)&b->bcast_addr.value;
	if (__tipc_nl_add_udp_addr(msg->skb, dst, TIPC_NLA_UDP_REMOTE))
		goto msg_full;

	if (!list_empty(&ub->rcast.list)) {
		if (nla_put_flag(msg->skb, TIPC_NLA_UDP_MULTI_REMOTEIP))
			goto msg_full;
	}

	nla_nest_end(msg->skb, nest);
	return 0;
msg_full:
	nla_nest_cancel(msg->skb, nest);
	return -EMSGSIZE;
}

/**
 * tipc_parse_udp_addr - build udp media address from netlink data
 * @nlattr:	netlink attribute containing sockaddr storage aligned address
 * @addr:	tipc media address to fill with address, port and protocol type
 * @scope_id:	IPv6 scope id pointer, not NULL indicates it's required
 */

static int tipc_parse_udp_addr(struct nlattr *nla, struct udp_media_addr *addr,
			       u32 *scope_id)
{
	struct sockaddr_storage sa;

	nla_memcpy(&sa, nla, sizeof(sa));
	if (sa.ss_family == AF_INET) {
		struct sockaddr_in *ip4 = (struct sockaddr_in *)&sa;

		addr->proto = htons(ETH_P_IP);
		addr->port = ip4->sin_port;
		addr->ipv4.s_addr = ip4->sin_addr.s_addr;
		return 0;

#if IS_ENABLED(CONFIG_IPV6)
	} else if (sa.ss_family == AF_INET6) {
		struct sockaddr_in6 *ip6 = (struct sockaddr_in6 *)&sa;

		addr->proto = htons(ETH_P_IPV6);
		addr->port = ip6->sin6_port;
		memcpy(&addr->ipv6, &ip6->sin6_addr, sizeof(struct in6_addr));

		/* Scope ID is only interesting for local addresses */
		if (scope_id) {
			int atype;

			atype = ipv6_addr_type(&ip6->sin6_addr);
			if (__ipv6_addr_needs_scope_id(atype) &&
			    !ip6->sin6_scope_id) {
				return -EINVAL;
			}

			*scope_id = ip6->sin6_scope_id ? : 0;
		}

		return 0;
#endif
	}
	return -EADDRNOTAVAIL;
}

int tipc_udp_nl_bearer_add(struct tipc_bearer *b, struct nlattr *attr)
{
	int err;
	struct udp_media_addr addr = {0};
	struct nlattr *opts[TIPC_NLA_UDP_MAX + 1];
	struct udp_media_addr *dst;

	if (nla_parse_nested_deprecated(opts, TIPC_NLA_UDP_MAX, attr, tipc_nl_udp_policy, NULL))
		return -EINVAL;

	if (!opts[TIPC_NLA_UDP_REMOTE])
		return -EINVAL;

	err = tipc_parse_udp_addr(opts[TIPC_NLA_UDP_REMOTE], &addr, NULL);
	if (err)
		return err;

	dst = (struct udp_media_addr *)&b->bcast_addr.value;
	if (tipc_udp_is_mcast_addr(dst)) {
		pr_err("Can't add remote ip to TIPC UDP multicast bearer\n");
		return -EINVAL;
	}

	if (tipc_udp_is_known_peer(b, &addr))
		return 0;

	return tipc_udp_rcast_add(b, &addr);
}

/**
 * tipc_udp_enable - callback to create a new udp bearer instance
 * @net:	network namespace
 * @b:		pointer to generic tipc_bearer
 * @attrs:	netlink bearer configuration
 *
 * validate the bearer parameters and initialize the udp bearer
 * rtnl_lock should be held
 */
static int tipc_udp_enable(struct net *net, struct tipc_bearer *b,
			   struct nlattr *attrs[])
{
	int err = -EINVAL;
	struct udp_bearer *ub;
	struct udp_media_addr remote = {0};
	struct udp_media_addr local = {0};
	struct udp_port_cfg udp_conf = {0};
	struct udp_tunnel_sock_cfg tuncfg = {NULL};
	struct nlattr *opts[TIPC_NLA_UDP_MAX + 1];
	u8 node_id[NODE_ID_LEN] = {0,};
	int rmcast = 0;

	ub = kzalloc(sizeof(*ub), GFP_ATOMIC);
	if (!ub)
		return -ENOMEM;

	INIT_LIST_HEAD(&ub->rcast.list);

	if (!attrs[TIPC_NLA_BEARER_UDP_OPTS])
		goto err;

	if (nla_parse_nested_deprecated(opts, TIPC_NLA_UDP_MAX, attrs[TIPC_NLA_BEARER_UDP_OPTS], tipc_nl_udp_policy, NULL))
		goto err;

	if (!opts[TIPC_NLA_UDP_LOCAL] || !opts[TIPC_NLA_UDP_REMOTE]) {
		pr_err("Invalid UDP bearer configuration");
		err = -EINVAL;
		goto err;
	}

	err = tipc_parse_udp_addr(opts[TIPC_NLA_UDP_LOCAL], &local,
				  &ub->ifindex);
	if (err)
		goto err;

	err = tipc_parse_udp_addr(opts[TIPC_NLA_UDP_REMOTE], &remote, NULL);
	if (err)
		goto err;

	if (remote.proto != local.proto) {
		err = -EINVAL;
		goto err;
	}

	/* Checking remote ip address */
	rmcast = tipc_udp_is_mcast_addr(&remote);

	/* Autoconfigure own node identity if needed */
	if (!tipc_own_id(net)) {
		memcpy(node_id, local.ipv6.in6_u.u6_addr8, 16);
		tipc_net_init(net, node_id, 0);
	}
	if (!tipc_own_id(net)) {
		pr_warn("Failed to set node id, please configure manually\n");
		err = -EINVAL;
		goto err;
	}

	b->bcast_addr.media_id = TIPC_MEDIA_TYPE_UDP;
	b->bcast_addr.broadcast = TIPC_BROADCAST_SUPPORT;
	rcu_assign_pointer(b->media_ptr, ub);
	rcu_assign_pointer(ub->bearer, b);
	tipc_udp_media_addr_set(&b->addr, &local);
	if (local.proto == htons(ETH_P_IP)) {
		struct net_device *dev;

		dev = __ip_dev_find(net, local.ipv4.s_addr, false);
		if (!dev) {
			err = -ENODEV;
			goto err;
		}
		udp_conf.family = AF_INET;

		/* Switch to use ANY to receive packets from group */
		if (rmcast)
			udp_conf.local_ip.s_addr = htonl(INADDR_ANY);
		else
			udp_conf.local_ip.s_addr = local.ipv4.s_addr;
		udp_conf.use_udp_checksums = false;
		ub->ifindex = dev->ifindex;
		if (tipc_mtu_bad(dev, sizeof(struct iphdr) +
				      sizeof(struct udphdr))) {
			err = -EINVAL;
			goto err;
		}
		b->mtu = b->media->mtu;
#if IS_ENABLED(CONFIG_IPV6)
	} else if (local.proto == htons(ETH_P_IPV6)) {
		udp_conf.family = AF_INET6;
		udp_conf.use_udp6_tx_checksums = true;
		udp_conf.use_udp6_rx_checksums = true;
		if (rmcast)
			udp_conf.local_ip6 = in6addr_any;
		else
			udp_conf.local_ip6 = local.ipv6;
		b->mtu = 1280;
#endif
	} else {
		err = -EAFNOSUPPORT;
		goto err;
	}
	udp_conf.local_udp_port = local.port;
	err = udp_sock_create(net, &udp_conf, &ub->ubsock);
	if (err)
		goto err;
	tuncfg.sk_user_data = ub;
	tuncfg.encap_type = 1;
	tuncfg.encap_rcv = tipc_udp_recv;
	tuncfg.encap_destroy = NULL;
	setup_udp_tunnel_sock(net, ub->ubsock, &tuncfg);

	err = dst_cache_init(&ub->rcast.dst_cache, GFP_ATOMIC);
	if (err)
		goto free;

	/**
	 * The bcast media address port is used for all peers and the ip
	 * is used if it's a multicast address.
	 */
	memcpy(&b->bcast_addr.value, &remote, sizeof(remote));
	if (rmcast)
		err = enable_mcast(ub, &remote);
	else
		err = tipc_udp_rcast_add(b, &remote);
	if (err)
		goto free;

	return 0;

free:
	dst_cache_destroy(&ub->rcast.dst_cache);
	udp_tunnel_sock_release(ub->ubsock);
err:
	kfree(ub);
	return err;
}

/* cleanup_bearer - break the socket/bearer association */
static void cleanup_bearer(struct work_struct *work)
{
	struct udp_bearer *ub = container_of(work, struct udp_bearer, work);
	struct udp_replicast *rcast, *tmp;

	list_for_each_entry_safe(rcast, tmp, &ub->rcast.list, list) {
		dst_cache_destroy(&rcast->dst_cache);
		list_del_rcu(&rcast->list);
		kfree_rcu(rcast, rcu);
	}

	dst_cache_destroy(&ub->rcast.dst_cache);
	udp_tunnel_sock_release(ub->ubsock);
	synchronize_net();
	kfree(ub);
}

/* tipc_udp_disable - detach bearer from socket */
static void tipc_udp_disable(struct tipc_bearer *b)
{
	struct udp_bearer *ub;

	ub = rtnl_dereference(b->media_ptr);
	if (!ub) {
		pr_err("UDP bearer instance not found\n");
		return;
	}
	sock_set_flag(ub->ubsock->sk, SOCK_DEAD);
	RCU_INIT_POINTER(ub->bearer, NULL);

	/* sock_release need to be done outside of rtnl lock */
	INIT_WORK(&ub->work, cleanup_bearer);
	schedule_work(&ub->work);
}

struct tipc_media udp_media_info = {
	.send_msg	= tipc_udp_send_msg,
	.enable_media	= tipc_udp_enable,
	.disable_media	= tipc_udp_disable,
	.addr2str	= tipc_udp_addr2str,
	.addr2msg	= tipc_udp_addr2msg,
	.msg2addr	= tipc_udp_msg2addr,
	.priority	= TIPC_DEF_LINK_PRI,
	.tolerance	= TIPC_DEF_LINK_TOL,
	.window		= TIPC_DEF_LINK_WIN,
	.mtu		= TIPC_DEF_LINK_UDP_MTU,
	.type_id	= TIPC_MEDIA_TYPE_UDP,
	.hwaddr_len	= 0,
	.name		= "udp"
};