/* 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"
#include "udp_media.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
 *
 * @proto: Ethernet protocol in use
 * @port: port being used
 * @ipv4: IPv4 address of neighbor
 * @ipv6: IPv6 address of neighbor
 */
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
 * @rcast:      associated udp_replicast container
 */
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 1;
        }

        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;
        int ttl, err;

        local_bh_disable();
        ndst = dst_cache_get(cache);
        if (dst->proto == htons(ETH_P_IP)) {
                struct rtable *rt = dst_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, 0);
#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
                        };
                        ndst = ipv6_stub->ipv6_dst_lookup_flow(net,
                                                               ub->ubsock->sk,
                                                               &fl6, NULL);
                        if (IS_ERR(ndst)) {
                                err = PTR_ERR(ndst);
                                goto tx_error;
                        }
                        dst_cache_set_ip6(cache, ndst, &fl6.saddr);
                }
                ttl = ip6_dst_hoplimit(ndst);
                udp_tunnel6_xmit_skb(ndst, ub->ubsock->sk, skb, NULL,
                                     &src->ipv6, &dst->ipv6, 0, ttl, 0,
                                     src->port, dst->port, false, 0);
#endif
        }
        local_bh_enable();
        return 0;

tx_error:
        local_bh_enable();
        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_obj(*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_SKB_CB(skb)->flags = 0;
                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 {
                lock_sock(sk);
                err = ipv6_stub->ipv6_sock_mc_join(sk, ub->ifindex,
                                                   &remote->ipv6);
                release_sock(sk);
#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)->info.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 || b->bcast_addr.media_id != TIPC_MEDIA_TYPE_UDP) {
                        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 || b->bcast_addr.media_id != TIPC_MEDIA_TYPE_UDP) {
                        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
 * @nla:        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,};
        struct net_device *dev;
        int rmcast = 0;

        ub = kzalloc_obj(*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)) {
                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;
                b->encap_hlen = sizeof(struct iphdr) + sizeof(struct udphdr);
                b->mtu = b->media->mtu;
#if IS_ENABLED(CONFIG_IPV6)
        } else if (local.proto == htons(ETH_P_IPV6)) {
                dev = ub->ifindex ? __dev_get_by_index(net, ub->ifindex) : NULL;
                dev = ipv6_dev_find(net, &local.ipv6, dev);
                if (!dev) {
                        err = -ENODEV;
                        goto err;
                }
                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;
                ub->ifindex = dev->ifindex;
                b->encap_hlen = sizeof(struct ipv6hdr) + sizeof(struct udphdr);
                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;
        struct tipc_net *tn;

        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);
        }

        tn = tipc_net(sock_net(ub->ubsock->sk));

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

        /* Note: could use a call_rcu() to avoid another synchronize_net() */
        synchronize_net();
        atomic_dec(&tn->wq_count);
        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 */
        atomic_inc(&tipc_net(sock_net(ub->ubsock->sk))->wq_count);
        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,
        .min_win        = TIPC_DEF_LINK_WIN,
        .max_win        = TIPC_DEF_LINK_WIN,
        .mtu            = TIPC_DEF_LINK_UDP_MTU,
        .type_id        = TIPC_MEDIA_TYPE_UDP,
        .hwaddr_len     = 0,
        .name           = "udp"
};