Merge remote-tracking branches 'asoc/topic/adsp', 'asoc/topic/ak4613', 'asoc/topic...

[mirror_ubuntu-bionic-kernel.git] / net / tipc / socket.c

/*
 * net/tipc/socket.c: TIPC socket API
 *
 * Copyright (c) 2001-2007, 2012-2016, Ericsson AB
 * Copyright (c) 2004-2008, 2010-2013, Wind River Systems
 * 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/rhashtable.h>
#include <linux/sched/signal.h>

#include "core.h"
#include "name_table.h"
#include "node.h"
#include "link.h"
#include "name_distr.h"
#include "socket.h"
#include "bcast.h"
#include "netlink.h"

#define CONN_TIMEOUT_DEFAULT    8000    /* default connect timeout = 8s */
#define CONN_PROBING_INTERVAL   msecs_to_jiffies(3600000)  /* [ms] => 1 h */
#define TIPC_FWD_MSG            1
#define TIPC_MAX_PORT           0xffffffff
#define TIPC_MIN_PORT           1

enum {
        TIPC_LISTEN = TCP_LISTEN,
        TIPC_ESTABLISHED = TCP_ESTABLISHED,
        TIPC_OPEN = TCP_CLOSE,
        TIPC_DISCONNECTING = TCP_CLOSE_WAIT,
        TIPC_CONNECTING = TCP_SYN_SENT,
};

/**
 * struct tipc_sock - TIPC socket structure
 * @sk: socket - interacts with 'port' and with user via the socket API
 * @conn_type: TIPC type used when connection was established
 * @conn_instance: TIPC instance used when connection was established
 * @published: non-zero if port has one or more associated names
 * @max_pkt: maximum packet size "hint" used when building messages sent by port
 * @portid: unique port identity in TIPC socket hash table
 * @phdr: preformatted message header used when sending messages
 * #cong_links: list of congested links
 * @publications: list of publications for port
 * @blocking_link: address of the congested link we are currently sleeping on
 * @pub_count: total # of publications port has made during its lifetime
 * @probing_state:
 * @conn_timeout: the time we can wait for an unresponded setup request
 * @dupl_rcvcnt: number of bytes counted twice, in both backlog and rcv queue
 * @cong_link_cnt: number of congested links
 * @sent_unacked: # messages sent by socket, and not yet acked by peer
 * @rcv_unacked: # messages read by user, but not yet acked back to peer
 * @peer: 'connected' peer for dgram/rdm
 * @node: hash table node
 * @mc_method: cookie for use between socket and broadcast layer
 * @rcu: rcu struct for tipc_sock
 */
struct tipc_sock {
        struct sock sk;
        u32 conn_type;
        u32 conn_instance;
        int published;
        u32 max_pkt;
        u32 portid;
        struct tipc_msg phdr;
        struct list_head cong_links;
        struct list_head publications;
        u32 pub_count;
        uint conn_timeout;
        atomic_t dupl_rcvcnt;
        bool probe_unacked;
        u16 cong_link_cnt;
        u16 snt_unacked;
        u16 snd_win;
        u16 peer_caps;
        u16 rcv_unacked;
        u16 rcv_win;
        struct sockaddr_tipc peer;
        struct rhash_head node;
        struct tipc_mc_method mc_method;
        struct rcu_head rcu;
};

static int tipc_backlog_rcv(struct sock *sk, struct sk_buff *skb);
static void tipc_data_ready(struct sock *sk);
static void tipc_write_space(struct sock *sk);
static void tipc_sock_destruct(struct sock *sk);
static int tipc_release(struct socket *sock);
static int tipc_accept(struct socket *sock, struct socket *new_sock, int flags,
                       bool kern);
static void tipc_sk_timeout(unsigned long data);
static int tipc_sk_publish(struct tipc_sock *tsk, uint scope,
                           struct tipc_name_seq const *seq);
static int tipc_sk_withdraw(struct tipc_sock *tsk, uint scope,
                            struct tipc_name_seq const *seq);
static struct tipc_sock *tipc_sk_lookup(struct net *net, u32 portid);
static int tipc_sk_insert(struct tipc_sock *tsk);
static void tipc_sk_remove(struct tipc_sock *tsk);
static int __tipc_sendstream(struct socket *sock, struct msghdr *m, size_t dsz);
static int __tipc_sendmsg(struct socket *sock, struct msghdr *m, size_t dsz);

static const struct proto_ops packet_ops;
static const struct proto_ops stream_ops;
static const struct proto_ops msg_ops;
static struct proto tipc_proto;
static const struct rhashtable_params tsk_rht_params;

static u32 tsk_own_node(struct tipc_sock *tsk)
{
        return msg_prevnode(&tsk->phdr);
}

static u32 tsk_peer_node(struct tipc_sock *tsk)
{
        return msg_destnode(&tsk->phdr);
}

static u32 tsk_peer_port(struct tipc_sock *tsk)
{
        return msg_destport(&tsk->phdr);
}

static  bool tsk_unreliable(struct tipc_sock *tsk)
{
        return msg_src_droppable(&tsk->phdr) != 0;
}

static void tsk_set_unreliable(struct tipc_sock *tsk, bool unreliable)
{
        msg_set_src_droppable(&tsk->phdr, unreliable ? 1 : 0);
}

static bool tsk_unreturnable(struct tipc_sock *tsk)
{
        return msg_dest_droppable(&tsk->phdr) != 0;
}

static void tsk_set_unreturnable(struct tipc_sock *tsk, bool unreturnable)
{
        msg_set_dest_droppable(&tsk->phdr, unreturnable ? 1 : 0);
}

static int tsk_importance(struct tipc_sock *tsk)
{
        return msg_importance(&tsk->phdr);
}

static int tsk_set_importance(struct tipc_sock *tsk, int imp)
{
        if (imp > TIPC_CRITICAL_IMPORTANCE)
                return -EINVAL;
        msg_set_importance(&tsk->phdr, (u32)imp);
        return 0;
}

static struct tipc_sock *tipc_sk(const struct sock *sk)
{
        return container_of(sk, struct tipc_sock, sk);
}

static bool tsk_conn_cong(struct tipc_sock *tsk)
{
        return tsk->snt_unacked > tsk->snd_win;
}

/* tsk_blocks(): translate a buffer size in bytes to number of
 * advertisable blocks, taking into account the ratio truesize(len)/len
 * We can trust that this ratio is always < 4 for len >= FLOWCTL_BLK_SZ
 */
static u16 tsk_adv_blocks(int len)
{
        return len / FLOWCTL_BLK_SZ / 4;
}

/* tsk_inc(): increment counter for sent or received data
 * - If block based flow control is not supported by peer we
 *   fall back to message based ditto, incrementing the counter
 */
static u16 tsk_inc(struct tipc_sock *tsk, int msglen)
{
        if (likely(tsk->peer_caps & TIPC_BLOCK_FLOWCTL))
                return ((msglen / FLOWCTL_BLK_SZ) + 1);
        return 1;
}

/**
 * tsk_advance_rx_queue - discard first buffer in socket receive queue
 *
 * Caller must hold socket lock
 */
static void tsk_advance_rx_queue(struct sock *sk)
{
        kfree_skb(__skb_dequeue(&sk->sk_receive_queue));
}

/* tipc_sk_respond() : send response message back to sender
 */
static void tipc_sk_respond(struct sock *sk, struct sk_buff *skb, int err)
{
        u32 selector;
        u32 dnode;
        u32 onode = tipc_own_addr(sock_net(sk));

        if (!tipc_msg_reverse(onode, &skb, err))
                return;

        dnode = msg_destnode(buf_msg(skb));
        selector = msg_origport(buf_msg(skb));
        tipc_node_xmit_skb(sock_net(sk), skb, dnode, selector);
}

/**
 * tsk_rej_rx_queue - reject all buffers in socket receive queue
 *
 * Caller must hold socket lock
 */
static void tsk_rej_rx_queue(struct sock *sk)
{
        struct sk_buff *skb;

        while ((skb = __skb_dequeue(&sk->sk_receive_queue)))
                tipc_sk_respond(sk, skb, TIPC_ERR_NO_PORT);
}

static bool tipc_sk_connected(struct sock *sk)
{
        return sk->sk_state == TIPC_ESTABLISHED;
}

/* tipc_sk_type_connectionless - check if the socket is datagram socket
 * @sk: socket
 *
 * Returns true if connection less, false otherwise
 */
static bool tipc_sk_type_connectionless(struct sock *sk)
{
        return sk->sk_type == SOCK_RDM || sk->sk_type == SOCK_DGRAM;
}

/* tsk_peer_msg - verify if message was sent by connected port's peer
 *
 * Handles cases where the node's network address has changed from
 * the default of <0.0.0> to its configured setting.
 */
static bool tsk_peer_msg(struct tipc_sock *tsk, struct tipc_msg *msg)
{
        struct sock *sk = &tsk->sk;
        struct tipc_net *tn = net_generic(sock_net(sk), tipc_net_id);
        u32 peer_port = tsk_peer_port(tsk);
        u32 orig_node;
        u32 peer_node;

        if (unlikely(!tipc_sk_connected(sk)))
                return false;

        if (unlikely(msg_origport(msg) != peer_port))
                return false;

        orig_node = msg_orignode(msg);
        peer_node = tsk_peer_node(tsk);

        if (likely(orig_node == peer_node))
                return true;

        if (!orig_node && (peer_node == tn->own_addr))
                return true;

        if (!peer_node && (orig_node == tn->own_addr))
                return true;

        return false;
}

/* tipc_set_sk_state - set the sk_state of the socket
 * @sk: socket
 *
 * Caller must hold socket lock
 *
 * Returns 0 on success, errno otherwise
 */
static int tipc_set_sk_state(struct sock *sk, int state)
{
        int oldsk_state = sk->sk_state;
        int res = -EINVAL;

        switch (state) {
        case TIPC_OPEN:
                res = 0;
                break;
        case TIPC_LISTEN:
        case TIPC_CONNECTING:
                if (oldsk_state == TIPC_OPEN)
                        res = 0;
                break;
        case TIPC_ESTABLISHED:
                if (oldsk_state == TIPC_CONNECTING ||
                    oldsk_state == TIPC_OPEN)
                        res = 0;
                break;
        case TIPC_DISCONNECTING:
                if (oldsk_state == TIPC_CONNECTING ||
                    oldsk_state == TIPC_ESTABLISHED)
                        res = 0;
                break;
        }

        if (!res)
                sk->sk_state = state;

        return res;
}

static int tipc_sk_sock_err(struct socket *sock, long *timeout)
{
        struct sock *sk = sock->sk;
        int err = sock_error(sk);
        int typ = sock->type;

        if (err)
                return err;
        if (typ == SOCK_STREAM || typ == SOCK_SEQPACKET) {
                if (sk->sk_state == TIPC_DISCONNECTING)
                        return -EPIPE;
                else if (!tipc_sk_connected(sk))
                        return -ENOTCONN;
        }
        if (!*timeout)
                return -EAGAIN;
        if (signal_pending(current))
                return sock_intr_errno(*timeout);

        return 0;
}

#define tipc_wait_for_cond(sock_, timeout_, condition_)                 \
({                                                                      \
        int rc_ = 0;                                                    \
        int done_ = 0;                                                  \
                                                                        \
        while (!(condition_) && !done_) {                               \
                struct sock *sk_ = sock->sk;                            \
                DEFINE_WAIT_FUNC(wait_, woken_wake_function);           \
                                                                        \
                rc_ = tipc_sk_sock_err(sock_, timeout_);                \
                if (rc_)                                                \
                        break;                                          \
                prepare_to_wait(sk_sleep(sk_), &wait_,                  \
                                TASK_INTERRUPTIBLE);                    \
                done_ = sk_wait_event(sk_, timeout_,                    \
                                      (condition_), &wait_);            \
                remove_wait_queue(sk_sleep(sk_), &wait_);               \
        }                                                               \
        rc_;                                                            \
})

/**
 * tipc_sk_create - create a TIPC socket
 * @net: network namespace (must be default network)
 * @sock: pre-allocated socket structure
 * @protocol: protocol indicator (must be 0)
 * @kern: caused by kernel or by userspace?
 *
 * This routine creates additional data structures used by the TIPC socket,
 * initializes them, and links them together.
 *
 * Returns 0 on success, errno otherwise
 */
static int tipc_sk_create(struct net *net, struct socket *sock,
                          int protocol, int kern)
{
        struct tipc_net *tn;
        const struct proto_ops *ops;
        struct sock *sk;
        struct tipc_sock *tsk;
        struct tipc_msg *msg;

        /* Validate arguments */
        if (unlikely(protocol != 0))
                return -EPROTONOSUPPORT;

        switch (sock->type) {
        case SOCK_STREAM:
                ops = &stream_ops;
                break;
        case SOCK_SEQPACKET:
                ops = &packet_ops;
                break;
        case SOCK_DGRAM:
        case SOCK_RDM:
                ops = &msg_ops;
                break;
        default:
                return -EPROTOTYPE;
        }

        /* Allocate socket's protocol area */
        sk = sk_alloc(net, AF_TIPC, GFP_KERNEL, &tipc_proto, kern);
        if (sk == NULL)
                return -ENOMEM;

        tsk = tipc_sk(sk);
        tsk->max_pkt = MAX_PKT_DEFAULT;
        INIT_LIST_HEAD(&tsk->publications);
        INIT_LIST_HEAD(&tsk->cong_links);
        msg = &tsk->phdr;
        tn = net_generic(sock_net(sk), tipc_net_id);

        /* Finish initializing socket data structures */
        sock->ops = ops;
        sock_init_data(sock, sk);
        tipc_set_sk_state(sk, TIPC_OPEN);
        if (tipc_sk_insert(tsk)) {
                pr_warn("Socket create failed; port number exhausted\n");
                return -EINVAL;
        }

        /* Ensure tsk is visible before we read own_addr. */
        smp_mb();

        tipc_msg_init(tn->own_addr, msg, TIPC_LOW_IMPORTANCE, TIPC_NAMED_MSG,
                      NAMED_H_SIZE, 0);

        msg_set_origport(msg, tsk->portid);
        setup_timer(&sk->sk_timer, tipc_sk_timeout, (unsigned long)tsk);
        sk->sk_shutdown = 0;
        sk->sk_backlog_rcv = tipc_backlog_rcv;
        sk->sk_rcvbuf = sysctl_tipc_rmem[1];
        sk->sk_data_ready = tipc_data_ready;
        sk->sk_write_space = tipc_write_space;
        sk->sk_destruct = tipc_sock_destruct;
        tsk->conn_timeout = CONN_TIMEOUT_DEFAULT;
        atomic_set(&tsk->dupl_rcvcnt, 0);

        /* Start out with safe limits until we receive an advertised window */
        tsk->snd_win = tsk_adv_blocks(RCVBUF_MIN);
        tsk->rcv_win = tsk->snd_win;

        if (tipc_sk_type_connectionless(sk)) {
                tsk_set_unreturnable(tsk, true);
                if (sock->type == SOCK_DGRAM)
                        tsk_set_unreliable(tsk, true);
        }

        return 0;
}

static void tipc_sk_callback(struct rcu_head *head)
{
        struct tipc_sock *tsk = container_of(head, struct tipc_sock, rcu);

        sock_put(&tsk->sk);
}

/* Caller should hold socket lock for the socket. */
static void __tipc_shutdown(struct socket *sock, int error)
{
        struct sock *sk = sock->sk;
        struct tipc_sock *tsk = tipc_sk(sk);
        struct net *net = sock_net(sk);
        long timeout = CONN_TIMEOUT_DEFAULT;
        u32 dnode = tsk_peer_node(tsk);
        struct sk_buff *skb;

        /* Avoid that hi-prio shutdown msgs bypass msgs in link wakeup queue */
        tipc_wait_for_cond(sock, &timeout, (!tsk->cong_link_cnt &&
                                            !tsk_conn_cong(tsk)));

        /* Reject all unreceived messages, except on an active connection
         * (which disconnects locally & sends a 'FIN+' to peer).
         */
        while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
                if (TIPC_SKB_CB(skb)->bytes_read) {
                        kfree_skb(skb);
                        continue;
                }
                if (!tipc_sk_type_connectionless(sk) &&
                    sk->sk_state != TIPC_DISCONNECTING) {
                        tipc_set_sk_state(sk, TIPC_DISCONNECTING);
                        tipc_node_remove_conn(net, dnode, tsk->portid);
                }
                tipc_sk_respond(sk, skb, error);
        }

        if (tipc_sk_type_connectionless(sk))
                return;

        if (sk->sk_state != TIPC_DISCONNECTING) {
                skb = tipc_msg_create(TIPC_CRITICAL_IMPORTANCE,
                                      TIPC_CONN_MSG, SHORT_H_SIZE, 0, dnode,
                                      tsk_own_node(tsk), tsk_peer_port(tsk),
                                      tsk->portid, error);
                if (skb)
                        tipc_node_xmit_skb(net, skb, dnode, tsk->portid);
                tipc_node_remove_conn(net, dnode, tsk->portid);
                tipc_set_sk_state(sk, TIPC_DISCONNECTING);
        }
}

/**
 * tipc_release - destroy a TIPC socket
 * @sock: socket to destroy
 *
 * This routine cleans up any messages that are still queued on the socket.
 * For DGRAM and RDM socket types, all queued messages are rejected.
 * For SEQPACKET and STREAM socket types, the first message is rejected
 * and any others are discarded.  (If the first message on a STREAM socket
 * is partially-read, it is discarded and the next one is rejected instead.)
 *
 * NOTE: Rejected messages are not necessarily returned to the sender!  They
 * are returned or discarded according to the "destination droppable" setting
 * specified for the message by the sender.
 *
 * Returns 0 on success, errno otherwise
 */
static int tipc_release(struct socket *sock)
{
        struct sock *sk = sock->sk;
        struct tipc_sock *tsk;

        /*
         * Exit if socket isn't fully initialized (occurs when a failed accept()
         * releases a pre-allocated child socket that was never used)
         */
        if (sk == NULL)
                return 0;

        tsk = tipc_sk(sk);
        lock_sock(sk);

        __tipc_shutdown(sock, TIPC_ERR_NO_PORT);
        sk->sk_shutdown = SHUTDOWN_MASK;
        tipc_sk_withdraw(tsk, 0, NULL);
        sk_stop_timer(sk, &sk->sk_timer);
        tipc_sk_remove(tsk);

        /* Reject any messages that accumulated in backlog queue */
        release_sock(sk);
        u32_list_purge(&tsk->cong_links);
        tsk->cong_link_cnt = 0;
        call_rcu(&tsk->rcu, tipc_sk_callback);
        sock->sk = NULL;

        return 0;
}

/**
 * tipc_bind - associate or disassocate TIPC name(s) with a socket
 * @sock: socket structure
 * @uaddr: socket address describing name(s) and desired operation
 * @uaddr_len: size of socket address data structure
 *
 * Name and name sequence binding is indicated using a positive scope value;
 * a negative scope value unbinds the specified name.  Specifying no name
 * (i.e. a socket address length of 0) unbinds all names from the socket.
 *
 * Returns 0 on success, errno otherwise
 *
 * NOTE: This routine doesn't need to take the socket lock since it doesn't
 *       access any non-constant socket information.
 */
static int tipc_bind(struct socket *sock, struct sockaddr *uaddr,
                     int uaddr_len)
{
        struct sock *sk = sock->sk;
        struct sockaddr_tipc *addr = (struct sockaddr_tipc *)uaddr;
        struct tipc_sock *tsk = tipc_sk(sk);
        int res = -EINVAL;

        lock_sock(sk);
        if (unlikely(!uaddr_len)) {
                res = tipc_sk_withdraw(tsk, 0, NULL);
                goto exit;
        }

        if (uaddr_len < sizeof(struct sockaddr_tipc)) {
                res = -EINVAL;
                goto exit;
        }
        if (addr->family != AF_TIPC) {
                res = -EAFNOSUPPORT;
                goto exit;
        }

        if (addr->addrtype == TIPC_ADDR_NAME)
                addr->addr.nameseq.upper = addr->addr.nameseq.lower;
        else if (addr->addrtype != TIPC_ADDR_NAMESEQ) {
                res = -EAFNOSUPPORT;
                goto exit;
        }

        if ((addr->addr.nameseq.type < TIPC_RESERVED_TYPES) &&
            (addr->addr.nameseq.type != TIPC_TOP_SRV) &&
            (addr->addr.nameseq.type != TIPC_CFG_SRV)) {
                res = -EACCES;
                goto exit;
        }

        res = (addr->scope > 0) ?
                tipc_sk_publish(tsk, addr->scope, &addr->addr.nameseq) :
                tipc_sk_withdraw(tsk, -addr->scope, &addr->addr.nameseq);
exit:
        release_sock(sk);
        return res;
}

/**
 * tipc_getname - get port ID of socket or peer socket
 * @sock: socket structure
 * @uaddr: area for returned socket address
 * @uaddr_len: area for returned length of socket address
 * @peer: 0 = own ID, 1 = current peer ID, 2 = current/former peer ID
 *
 * Returns 0 on success, errno otherwise
 *
 * NOTE: This routine doesn't need to take the socket lock since it only
 *       accesses socket information that is unchanging (or which changes in
 *       a completely predictable manner).
 */
static int tipc_getname(struct socket *sock, struct sockaddr *uaddr,
                        int *uaddr_len, int peer)
{
        struct sockaddr_tipc *addr = (struct sockaddr_tipc *)uaddr;
        struct sock *sk = sock->sk;
        struct tipc_sock *tsk = tipc_sk(sk);
        struct tipc_net *tn = net_generic(sock_net(sock->sk), tipc_net_id);

        memset(addr, 0, sizeof(*addr));
        if (peer) {
                if ((!tipc_sk_connected(sk)) &&
                    ((peer != 2) || (sk->sk_state != TIPC_DISCONNECTING)))
                        return -ENOTCONN;
                addr->addr.id.ref = tsk_peer_port(tsk);
                addr->addr.id.node = tsk_peer_node(tsk);
        } else {
                addr->addr.id.ref = tsk->portid;
                addr->addr.id.node = tn->own_addr;
        }

        *uaddr_len = sizeof(*addr);
        addr->addrtype = TIPC_ADDR_ID;
        addr->family = AF_TIPC;
        addr->scope = 0;
        addr->addr.name.domain = 0;

        return 0;
}

/**
 * tipc_poll - read and possibly block on pollmask
 * @file: file structure associated with the socket
 * @sock: socket for which to calculate the poll bits
 * @wait: ???
 *
 * Returns pollmask value
 *
 * COMMENTARY:
 * It appears that the usual socket locking mechanisms are not useful here
 * since the pollmask info is potentially out-of-date the moment this routine
 * exits.  TCP and other protocols seem to rely on higher level poll routines
 * to handle any preventable race conditions, so TIPC will do the same ...
 *
 * IMPORTANT: The fact that a read or write operation is indicated does NOT
 * imply that the operation will succeed, merely that it should be performed
 * and will not block.
 */
static unsigned int tipc_poll(struct file *file, struct socket *sock,
                              poll_table *wait)
{
        struct sock *sk = sock->sk;
        struct tipc_sock *tsk = tipc_sk(sk);
        u32 mask = 0;

        sock_poll_wait(file, sk_sleep(sk), wait);

        if (sk->sk_shutdown & RCV_SHUTDOWN)
                mask |= POLLRDHUP | POLLIN | POLLRDNORM;
        if (sk->sk_shutdown == SHUTDOWN_MASK)
                mask |= POLLHUP;

        switch (sk->sk_state) {
        case TIPC_ESTABLISHED:
                if (!tsk->cong_link_cnt && !tsk_conn_cong(tsk))
                        mask |= POLLOUT;
                /* fall thru' */
        case TIPC_LISTEN:
        case TIPC_CONNECTING:
                if (!skb_queue_empty(&sk->sk_receive_queue))
                        mask |= (POLLIN | POLLRDNORM);
                break;
        case TIPC_OPEN:
                if (!tsk->cong_link_cnt)
                        mask |= POLLOUT;
                if (tipc_sk_type_connectionless(sk) &&
                    (!skb_queue_empty(&sk->sk_receive_queue)))
                        mask |= (POLLIN | POLLRDNORM);
                break;
        case TIPC_DISCONNECTING:
                mask = (POLLIN | POLLRDNORM | POLLHUP);
                break;
        }

        return mask;
}

/**
 * tipc_sendmcast - send multicast message
 * @sock: socket structure
 * @seq: destination address
 * @msg: message to send
 * @dlen: length of data to send
 * @timeout: timeout to wait for wakeup
 *
 * Called from function tipc_sendmsg(), which has done all sanity checks
 * Returns the number of bytes sent on success, or errno
 */
static int tipc_sendmcast(struct  socket *sock, struct tipc_name_seq *seq,
                          struct msghdr *msg, size_t dlen, long timeout)
{
        struct sock *sk = sock->sk;
        struct tipc_sock *tsk = tipc_sk(sk);
        struct tipc_msg *hdr = &tsk->phdr;
        struct net *net = sock_net(sk);
        int mtu = tipc_bcast_get_mtu(net);
        struct tipc_mc_method *method = &tsk->mc_method;
        u32 domain = addr_domain(net, TIPC_CLUSTER_SCOPE);
        struct sk_buff_head pkts;
        struct tipc_nlist dsts;
        int rc;

        /* Block or return if any destination link is congested */
        rc = tipc_wait_for_cond(sock, &timeout, !tsk->cong_link_cnt);
        if (unlikely(rc))
                return rc;

        /* Lookup destination nodes */
        tipc_nlist_init(&dsts, tipc_own_addr(net));
        tipc_nametbl_lookup_dst_nodes(net, seq->type, seq->lower,
                                      seq->upper, domain, &dsts);
        if (!dsts.local && !dsts.remote)
                return -EHOSTUNREACH;

        /* Build message header */
        msg_set_type(hdr, TIPC_MCAST_MSG);
        msg_set_hdr_sz(hdr, MCAST_H_SIZE);
        msg_set_lookup_scope(hdr, TIPC_CLUSTER_SCOPE);
        msg_set_destport(hdr, 0);
        msg_set_destnode(hdr, 0);
        msg_set_nametype(hdr, seq->type);
        msg_set_namelower(hdr, seq->lower);
        msg_set_nameupper(hdr, seq->upper);

        /* Build message as chain of buffers */
        skb_queue_head_init(&pkts);
        rc = tipc_msg_build(hdr, msg, 0, dlen, mtu, &pkts);

        /* Send message if build was successful */
        if (unlikely(rc == dlen))
                rc = tipc_mcast_xmit(net, &pkts, method, &dsts,
                                     &tsk->cong_link_cnt);

        tipc_nlist_purge(&dsts);

        return rc ? rc : dlen;
}

/**
 * tipc_sk_mcast_rcv - Deliver multicast messages to all destination sockets
 * @arrvq: queue with arriving messages, to be cloned after destination lookup
 * @inputq: queue with cloned messages, delivered to socket after dest lookup
 *
 * Multi-threaded: parallel calls with reference to same queues may occur
 */
void tipc_sk_mcast_rcv(struct net *net, struct sk_buff_head *arrvq,
                       struct sk_buff_head *inputq)
{
        struct tipc_msg *msg;
        struct list_head dports;
        u32 portid;
        u32 scope = TIPC_CLUSTER_SCOPE;
        struct sk_buff_head tmpq;
        uint hsz;
        struct sk_buff *skb, *_skb;

        __skb_queue_head_init(&tmpq);
        INIT_LIST_HEAD(&dports);

        skb = tipc_skb_peek(arrvq, &inputq->lock);
        for (; skb; skb = tipc_skb_peek(arrvq, &inputq->lock)) {
                msg = buf_msg(skb);
                hsz = skb_headroom(skb) + msg_hdr_sz(msg);

                if (in_own_node(net, msg_orignode(msg)))
                        scope = TIPC_NODE_SCOPE;

                /* Create destination port list and message clones: */
                tipc_nametbl_mc_translate(net,
                                          msg_nametype(msg), msg_namelower(msg),
                                          msg_nameupper(msg), scope, &dports);
                portid = u32_pop(&dports);
                for (; portid; portid = u32_pop(&dports)) {
                        _skb = __pskb_copy(skb, hsz, GFP_ATOMIC);
                        if (_skb) {
                                msg_set_destport(buf_msg(_skb), portid);
                                __skb_queue_tail(&tmpq, _skb);
                                continue;
                        }
                        pr_warn("Failed to clone mcast rcv buffer\n");
                }
                /* Append to inputq if not already done by other thread */
                spin_lock_bh(&inputq->lock);
                if (skb_peek(arrvq) == skb) {
                        skb_queue_splice_tail_init(&tmpq, inputq);
                        kfree_skb(__skb_dequeue(arrvq));
                }
                spin_unlock_bh(&inputq->lock);
                __skb_queue_purge(&tmpq);
                kfree_skb(skb);
        }
        tipc_sk_rcv(net, inputq);
}

/**
 * tipc_sk_proto_rcv - receive a connection mng protocol message
 * @tsk: receiving socket
 * @skb: pointer to message buffer.
 */
static void tipc_sk_proto_rcv(struct tipc_sock *tsk, struct sk_buff *skb,
                              struct sk_buff_head *xmitq)
{
        struct sock *sk = &tsk->sk;
        u32 onode = tsk_own_node(tsk);
        struct tipc_msg *hdr = buf_msg(skb);
        int mtyp = msg_type(hdr);
        bool conn_cong;

        /* Ignore if connection cannot be validated: */
        if (!tsk_peer_msg(tsk, hdr))
                goto exit;

        tsk->probe_unacked = false;

        if (mtyp == CONN_PROBE) {
                msg_set_type(hdr, CONN_PROBE_REPLY);
                if (tipc_msg_reverse(onode, &skb, TIPC_OK))
                        __skb_queue_tail(xmitq, skb);
                return;
        } else if (mtyp == CONN_ACK) {
                conn_cong = tsk_conn_cong(tsk);
                tsk->snt_unacked -= msg_conn_ack(hdr);
                if (tsk->peer_caps & TIPC_BLOCK_FLOWCTL)
                        tsk->snd_win = msg_adv_win(hdr);
                if (conn_cong)
                        sk->sk_write_space(sk);
        } else if (mtyp != CONN_PROBE_REPLY) {
                pr_warn("Received unknown CONN_PROTO msg\n");
        }
exit:
        kfree_skb(skb);
}

/**
 * tipc_sendmsg - send message in connectionless manner
 * @sock: socket structure
 * @m: message to send
 * @dsz: amount of user data to be sent
 *
 * Message must have an destination specified explicitly.
 * Used for SOCK_RDM and SOCK_DGRAM messages,
 * and for 'SYN' messages on SOCK_SEQPACKET and SOCK_STREAM connections.
 * (Note: 'SYN+' is prohibited on SOCK_STREAM.)
 *
 * Returns the number of bytes sent on success, or errno otherwise
 */
static int tipc_sendmsg(struct socket *sock,
                        struct msghdr *m, size_t dsz)
{
        struct sock *sk = sock->sk;
        int ret;

        lock_sock(sk);
        ret = __tipc_sendmsg(sock, m, dsz);
        release_sock(sk);

        return ret;
}

static int __tipc_sendmsg(struct socket *sock, struct msghdr *m, size_t dlen)
{
        struct sock *sk = sock->sk;
        struct net *net = sock_net(sk);
        struct tipc_sock *tsk = tipc_sk(sk);
        DECLARE_SOCKADDR(struct sockaddr_tipc *, dest, m->msg_name);
        long timeout = sock_sndtimeo(sk, m->msg_flags & MSG_DONTWAIT);
        struct list_head *clinks = &tsk->cong_links;
        bool syn = !tipc_sk_type_connectionless(sk);
        struct tipc_msg *hdr = &tsk->phdr;
        struct tipc_name_seq *seq;
        struct sk_buff_head pkts;
        u32 type, inst, domain;
        u32 dnode, dport;
        int mtu, rc;

        if (unlikely(dlen > TIPC_MAX_USER_MSG_SIZE))
                return -EMSGSIZE;

        if (unlikely(!dest)) {
                dest = &tsk->peer;
                if (!syn || dest->family != AF_TIPC)
                        return -EDESTADDRREQ;
        }

        if (unlikely(m->msg_namelen < sizeof(*dest)))
                return -EINVAL;

        if (unlikely(dest->family != AF_TIPC))
                return -EINVAL;

        if (unlikely(syn)) {
                if (sk->sk_state == TIPC_LISTEN)
                        return -EPIPE;
                if (sk->sk_state != TIPC_OPEN)
                        return -EISCONN;
                if (tsk->published)
                        return -EOPNOTSUPP;
                if (dest->addrtype == TIPC_ADDR_NAME) {
                        tsk->conn_type = dest->addr.name.name.type;
                        tsk->conn_instance = dest->addr.name.name.instance;
                }
        }

        seq = &dest->addr.nameseq;
        if (dest->addrtype == TIPC_ADDR_MCAST)
                return tipc_sendmcast(sock, seq, m, dlen, timeout);

        if (dest->addrtype == TIPC_ADDR_NAME) {
                type = dest->addr.name.name.type;
                inst = dest->addr.name.name.instance;
                domain = dest->addr.name.domain;
                dnode = domain;
                msg_set_type(hdr, TIPC_NAMED_MSG);
                msg_set_hdr_sz(hdr, NAMED_H_SIZE);
                msg_set_nametype(hdr, type);
                msg_set_nameinst(hdr, inst);
                msg_set_lookup_scope(hdr, tipc_addr_scope(domain));
                dport = tipc_nametbl_translate(net, type, inst, &dnode);
                msg_set_destnode(hdr, dnode);
                msg_set_destport(hdr, dport);
                if (unlikely(!dport && !dnode))
                        return -EHOSTUNREACH;

        } else if (dest->addrtype == TIPC_ADDR_ID) {
                dnode = dest->addr.id.node;
                msg_set_type(hdr, TIPC_DIRECT_MSG);
                msg_set_lookup_scope(hdr, 0);
                msg_set_destnode(hdr, dnode);
                msg_set_destport(hdr, dest->addr.id.ref);
                msg_set_hdr_sz(hdr, BASIC_H_SIZE);
        }

        /* Block or return if destination link is congested */
        rc = tipc_wait_for_cond(sock, &timeout, !u32_find(clinks, dnode));
        if (unlikely(rc))
                return rc;

        skb_queue_head_init(&pkts);
        mtu = tipc_node_get_mtu(net, dnode, tsk->portid);
        rc = tipc_msg_build(hdr, m, 0, dlen, mtu, &pkts);
        if (unlikely(rc != dlen))
                return rc;

        rc = tipc_node_xmit(net, &pkts, dnode, tsk->portid);
        if (unlikely(rc == -ELINKCONG)) {
                u32_push(clinks, dnode);
                tsk->cong_link_cnt++;
                rc = 0;
        }

        if (unlikely(syn && !rc))
                tipc_set_sk_state(sk, TIPC_CONNECTING);

        return rc ? rc : dlen;
}

/**
 * tipc_sendstream - send stream-oriented data
 * @sock: socket structure
 * @m: data to send
 * @dsz: total length of data to be transmitted
 *
 * Used for SOCK_STREAM data.
 *
 * Returns the number of bytes sent on success (or partial success),
 * or errno if no data sent
 */
static int tipc_sendstream(struct socket *sock, struct msghdr *m, size_t dsz)
{
        struct sock *sk = sock->sk;
        int ret;

        lock_sock(sk);
        ret = __tipc_sendstream(sock, m, dsz);
        release_sock(sk);

        return ret;
}

static int __tipc_sendstream(struct socket *sock, struct msghdr *m, size_t dlen)
{
        struct sock *sk = sock->sk;
        DECLARE_SOCKADDR(struct sockaddr_tipc *, dest, m->msg_name);
        long timeout = sock_sndtimeo(sk, m->msg_flags & MSG_DONTWAIT);
        struct tipc_sock *tsk = tipc_sk(sk);
        struct tipc_msg *hdr = &tsk->phdr;
        struct net *net = sock_net(sk);
        struct sk_buff_head pkts;
        u32 dnode = tsk_peer_node(tsk);
        int send, sent = 0;
        int rc = 0;

        skb_queue_head_init(&pkts);

        if (unlikely(dlen > INT_MAX))
                return -EMSGSIZE;

        /* Handle implicit connection setup */
        if (unlikely(dest)) {
                rc = __tipc_sendmsg(sock, m, dlen);
                if (dlen && (dlen == rc))
                        tsk->snt_unacked = tsk_inc(tsk, dlen + msg_hdr_sz(hdr));
                return rc;
        }

        do {
                rc = tipc_wait_for_cond(sock, &timeout,
                                        (!tsk->cong_link_cnt &&
                                         !tsk_conn_cong(tsk) &&
                                         tipc_sk_connected(sk)));
                if (unlikely(rc))
                        break;

                send = min_t(size_t, dlen - sent, TIPC_MAX_USER_MSG_SIZE);
                rc = tipc_msg_build(hdr, m, sent, send, tsk->max_pkt, &pkts);
                if (unlikely(rc != send))
                        break;

                rc = tipc_node_xmit(net, &pkts, dnode, tsk->portid);
                if (unlikely(rc == -ELINKCONG)) {
                        tsk->cong_link_cnt = 1;
                        rc = 0;
                }
                if (likely(!rc)) {
                        tsk->snt_unacked += tsk_inc(tsk, send + MIN_H_SIZE);
                        sent += send;
                }
        } while (sent < dlen && !rc);

        return rc ? rc : sent;
}

/**
 * tipc_send_packet - send a connection-oriented message
 * @sock: socket structure
 * @m: message to send
 * @dsz: length of data to be transmitted
 *
 * Used for SOCK_SEQPACKET messages.
 *
 * Returns the number of bytes sent on success, or errno otherwise
 */
static int tipc_send_packet(struct socket *sock, struct msghdr *m, size_t dsz)
{
        if (dsz > TIPC_MAX_USER_MSG_SIZE)
                return -EMSGSIZE;

        return tipc_sendstream(sock, m, dsz);
}

/* tipc_sk_finish_conn - complete the setup of a connection
 */
static void tipc_sk_finish_conn(struct tipc_sock *tsk, u32 peer_port,
                                u32 peer_node)
{
        struct sock *sk = &tsk->sk;
        struct net *net = sock_net(sk);
        struct tipc_msg *msg = &tsk->phdr;

        msg_set_destnode(msg, peer_node);
        msg_set_destport(msg, peer_port);
        msg_set_type(msg, TIPC_CONN_MSG);
        msg_set_lookup_scope(msg, 0);
        msg_set_hdr_sz(msg, SHORT_H_SIZE);

        sk_reset_timer(sk, &sk->sk_timer, jiffies + CONN_PROBING_INTERVAL);
        tipc_set_sk_state(sk, TIPC_ESTABLISHED);
        tipc_node_add_conn(net, peer_node, tsk->portid, peer_port);
        tsk->max_pkt = tipc_node_get_mtu(net, peer_node, tsk->portid);
        tsk->peer_caps = tipc_node_get_capabilities(net, peer_node);
        if (tsk->peer_caps & TIPC_BLOCK_FLOWCTL)
                return;

        /* Fall back to message based flow control */
        tsk->rcv_win = FLOWCTL_MSG_WIN;
        tsk->snd_win = FLOWCTL_MSG_WIN;
}

/**
 * set_orig_addr - capture sender's address for received message
 * @m: descriptor for message info
 * @msg: received message header
 *
 * Note: Address is not captured if not requested by receiver.
 */
static void set_orig_addr(struct msghdr *m, struct tipc_msg *msg)
{
        DECLARE_SOCKADDR(struct sockaddr_tipc *, addr, m->msg_name);

        if (addr) {
                addr->family = AF_TIPC;
                addr->addrtype = TIPC_ADDR_ID;
                memset(&addr->addr, 0, sizeof(addr->addr));
                addr->addr.id.ref = msg_origport(msg);
                addr->addr.id.node = msg_orignode(msg);
                addr->addr.name.domain = 0;     /* could leave uninitialized */
                addr->scope = 0;                /* could leave uninitialized */
                m->msg_namelen = sizeof(struct sockaddr_tipc);
        }
}

/**
 * tipc_sk_anc_data_recv - optionally capture ancillary data for received message
 * @m: descriptor for message info
 * @msg: received message header
 * @tsk: TIPC port associated with message
 *
 * Note: Ancillary data is not captured if not requested by receiver.
 *
 * Returns 0 if successful, otherwise errno
 */
static int tipc_sk_anc_data_recv(struct msghdr *m, struct tipc_msg *msg,
                                 struct tipc_sock *tsk)
{
        u32 anc_data[3];
        u32 err;
        u32 dest_type;
        int has_name;
        int res;

        if (likely(m->msg_controllen == 0))
                return 0;

        /* Optionally capture errored message object(s) */
        err = msg ? msg_errcode(msg) : 0;
        if (unlikely(err)) {
                anc_data[0] = err;
                anc_data[1] = msg_data_sz(msg);
                res = put_cmsg(m, SOL_TIPC, TIPC_ERRINFO, 8, anc_data);
                if (res)
                        return res;
                if (anc_data[1]) {
                        res = put_cmsg(m, SOL_TIPC, TIPC_RETDATA, anc_data[1],
                                       msg_data(msg));
                        if (res)
                                return res;
                }
        }

        /* Optionally capture message destination object */
        dest_type = msg ? msg_type(msg) : TIPC_DIRECT_MSG;
        switch (dest_type) {
        case TIPC_NAMED_MSG:
                has_name = 1;
                anc_data[0] = msg_nametype(msg);
                anc_data[1] = msg_namelower(msg);
                anc_data[2] = msg_namelower(msg);
                break;
        case TIPC_MCAST_MSG:
                has_name = 1;
                anc_data[0] = msg_nametype(msg);
                anc_data[1] = msg_namelower(msg);
                anc_data[2] = msg_nameupper(msg);
                break;
        case TIPC_CONN_MSG:
                has_name = (tsk->conn_type != 0);
                anc_data[0] = tsk->conn_type;
                anc_data[1] = tsk->conn_instance;
                anc_data[2] = tsk->conn_instance;
                break;
        default:
                has_name = 0;
        }
        if (has_name) {
                res = put_cmsg(m, SOL_TIPC, TIPC_DESTNAME, 12, anc_data);
                if (res)
                        return res;
        }

        return 0;
}

static void tipc_sk_send_ack(struct tipc_sock *tsk)
{
        struct sock *sk = &tsk->sk;
        struct net *net = sock_net(sk);
        struct sk_buff *skb = NULL;
        struct tipc_msg *msg;
        u32 peer_port = tsk_peer_port(tsk);
        u32 dnode = tsk_peer_node(tsk);

        if (!tipc_sk_connected(sk))
                return;
        skb = tipc_msg_create(CONN_MANAGER, CONN_ACK, INT_H_SIZE, 0,
                              dnode, tsk_own_node(tsk), peer_port,
                              tsk->portid, TIPC_OK);
        if (!skb)
                return;
        msg = buf_msg(skb);
        msg_set_conn_ack(msg, tsk->rcv_unacked);
        tsk->rcv_unacked = 0;

        /* Adjust to and advertize the correct window limit */
        if (tsk->peer_caps & TIPC_BLOCK_FLOWCTL) {
                tsk->rcv_win = tsk_adv_blocks(tsk->sk.sk_rcvbuf);
                msg_set_adv_win(msg, tsk->rcv_win);
        }
        tipc_node_xmit_skb(net, skb, dnode, msg_link_selector(msg));
}

static int tipc_wait_for_rcvmsg(struct socket *sock, long *timeop)
{
        struct sock *sk = sock->sk;
        DEFINE_WAIT(wait);
        long timeo = *timeop;
        int err;

        for (;;) {
                prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
                if (timeo && skb_queue_empty(&sk->sk_receive_queue)) {
                        if (sk->sk_shutdown & RCV_SHUTDOWN) {
                                err = -ENOTCONN;
                                break;
                        }
                        release_sock(sk);
                        timeo = schedule_timeout(timeo);
                        lock_sock(sk);
                }
                err = 0;
                if (!skb_queue_empty(&sk->sk_receive_queue))
                        break;
                err = -EAGAIN;
                if (!timeo)
                        break;
                err = sock_intr_errno(timeo);
                if (signal_pending(current))
                        break;
        }
        finish_wait(sk_sleep(sk), &wait);
        *timeop = timeo;
        return err;
}

/**
 * tipc_recvmsg - receive packet-oriented message
 * @m: descriptor for message info
 * @buf_len: total size of user buffer area
 * @flags: receive flags
 *
 * Used for SOCK_DGRAM, SOCK_RDM, and SOCK_SEQPACKET messages.
 * If the complete message doesn't fit in user area, truncate it.
 *
 * Returns size of returned message data, errno otherwise
 */
static int tipc_recvmsg(struct socket *sock, struct msghdr *m, size_t buf_len,
                        int flags)
{
        struct sock *sk = sock->sk;
        struct tipc_sock *tsk = tipc_sk(sk);
        struct sk_buff *buf;
        struct tipc_msg *msg;
        bool is_connectionless = tipc_sk_type_connectionless(sk);
        long timeo;
        unsigned int sz;
        u32 err;
        int res, hlen;

        /* Catch invalid receive requests */
        if (unlikely(!buf_len))
                return -EINVAL;

        lock_sock(sk);

        if (!is_connectionless && unlikely(sk->sk_state == TIPC_OPEN)) {
                res = -ENOTCONN;
                goto exit;
        }

        timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
restart:

        /* Look for a message in receive queue; wait if necessary */
        res = tipc_wait_for_rcvmsg(sock, &timeo);
        if (res)
                goto exit;

        /* Look at first message in receive queue */
        buf = skb_peek(&sk->sk_receive_queue);
        msg = buf_msg(buf);
        sz = msg_data_sz(msg);
        hlen = msg_hdr_sz(msg);
        err = msg_errcode(msg);

        /* Discard an empty non-errored message & try again */
        if ((!sz) && (!err)) {
                tsk_advance_rx_queue(sk);
                goto restart;
        }

        /* Capture sender's address (optional) */
        set_orig_addr(m, msg);

        /* Capture ancillary data (optional) */
        res = tipc_sk_anc_data_recv(m, msg, tsk);
        if (res)
                goto exit;

        /* Capture message data (if valid) & compute return value (always) */
        if (!err) {
                if (unlikely(buf_len < sz)) {
                        sz = buf_len;
                        m->msg_flags |= MSG_TRUNC;
                }
                res = skb_copy_datagram_msg(buf, hlen, m, sz);
                if (res)
                        goto exit;
                res = sz;
        } else {
                if (is_connectionless || err == TIPC_CONN_SHUTDOWN ||
                    m->msg_control)
                        res = 0;
                else
                        res = -ECONNRESET;
        }

        if (unlikely(flags & MSG_PEEK))
                goto exit;

        if (likely(!is_connectionless)) {
                tsk->rcv_unacked += tsk_inc(tsk, hlen + sz);
                if (unlikely(tsk->rcv_unacked >= (tsk->rcv_win / 4)))
                        tipc_sk_send_ack(tsk);
        }
        tsk_advance_rx_queue(sk);
exit:
        release_sock(sk);
        return res;
}

/**
 * tipc_recv_stream - receive stream-oriented data
 * @m: descriptor for message info
 * @buf_len: total size of user buffer area
 * @flags: receive flags
 *
 * Used for SOCK_STREAM messages only.  If not enough data is available
 * will optionally wait for more; never truncates data.
 *
 * Returns size of returned message data, errno otherwise
 */
static int tipc_recv_stream(struct socket *sock, struct msghdr *m,
                            size_t buf_len, int flags)
{
        struct sock *sk = sock->sk;
        struct tipc_sock *tsk = tipc_sk(sk);
        struct sk_buff *buf;
        struct tipc_msg *msg;
        long timeo;
        unsigned int sz;
        int target;
        int sz_copied = 0;
        u32 err;
        int res = 0, hlen;

        /* Catch invalid receive attempts */
        if (unlikely(!buf_len))
                return -EINVAL;

        lock_sock(sk);

        if (unlikely(sk->sk_state == TIPC_OPEN)) {
                res = -ENOTCONN;
                goto exit;
        }

        target = sock_rcvlowat(sk, flags & MSG_WAITALL, buf_len);
        timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);

restart:
        /* Look for a message in receive queue; wait if necessary */
        res = tipc_wait_for_rcvmsg(sock, &timeo);
        if (res)
                goto exit;

        /* Look at first message in receive queue */
        buf = skb_peek(&sk->sk_receive_queue);
        msg = buf_msg(buf);
        sz = msg_data_sz(msg);
        hlen = msg_hdr_sz(msg);
        err = msg_errcode(msg);

        /* Discard an empty non-errored message & try again */
        if ((!sz) && (!err)) {
                tsk_advance_rx_queue(sk);
                goto restart;
        }

        /* Optionally capture sender's address & ancillary data of first msg */
        if (sz_copied == 0) {
                set_orig_addr(m, msg);
                res = tipc_sk_anc_data_recv(m, msg, tsk);
                if (res)
                        goto exit;
        }

        /* Capture message data (if valid) & compute return value (always) */
        if (!err) {
                u32 offset = TIPC_SKB_CB(buf)->bytes_read;
                u32 needed;
                int sz_to_copy;

                sz -= offset;
                needed = (buf_len - sz_copied);
                sz_to_copy = min(sz, needed);

                res = skb_copy_datagram_msg(buf, hlen + offset, m, sz_to_copy);
                if (res)
                        goto exit;

                sz_copied += sz_to_copy;

                if (sz_to_copy < sz) {
                        if (!(flags & MSG_PEEK))
                                TIPC_SKB_CB(buf)->bytes_read =
                                        offset + sz_to_copy;
                        goto exit;
                }
        } else {
                if (sz_copied != 0)
                        goto exit; /* can't add error msg to valid data */

                if ((err == TIPC_CONN_SHUTDOWN) || m->msg_control)
                        res = 0;
                else
                        res = -ECONNRESET;
        }

        if (unlikely(flags & MSG_PEEK))
                goto exit;

        tsk->rcv_unacked += tsk_inc(tsk, hlen + sz);
        if (unlikely(tsk->rcv_unacked >= (tsk->rcv_win / 4)))
                tipc_sk_send_ack(tsk);
        tsk_advance_rx_queue(sk);

        /* Loop around if more data is required */
        if ((sz_copied < buf_len) &&    /* didn't get all requested data */
            (!skb_queue_empty(&sk->sk_receive_queue) ||
            (sz_copied < target)) &&    /* and more is ready or required */
            (!err))                     /* and haven't reached a FIN */
                goto restart;

exit:
        release_sock(sk);
        return sz_copied ? sz_copied : res;
}

/**
 * tipc_write_space - wake up thread if port congestion is released
 * @sk: socket
 */
static void tipc_write_space(struct sock *sk)
{
        struct socket_wq *wq;

        rcu_read_lock();
        wq = rcu_dereference(sk->sk_wq);
        if (skwq_has_sleeper(wq))
                wake_up_interruptible_sync_poll(&wq->wait, POLLOUT |
                                                POLLWRNORM | POLLWRBAND);
        rcu_read_unlock();
}

/**
 * tipc_data_ready - wake up threads to indicate messages have been received
 * @sk: socket
 * @len: the length of messages
 */
static void tipc_data_ready(struct sock *sk)
{
        struct socket_wq *wq;

        rcu_read_lock();
        wq = rcu_dereference(sk->sk_wq);
        if (skwq_has_sleeper(wq))
                wake_up_interruptible_sync_poll(&wq->wait, POLLIN |
                                                POLLRDNORM | POLLRDBAND);
        rcu_read_unlock();
}

static void tipc_sock_destruct(struct sock *sk)
{
        __skb_queue_purge(&sk->sk_receive_queue);
}

/**
 * filter_connect - Handle all incoming messages for a connection-based socket
 * @tsk: TIPC socket
 * @skb: pointer to message buffer. Set to NULL if buffer is consumed
 *
 * Returns true if everything ok, false otherwise
 */
static bool filter_connect(struct tipc_sock *tsk, struct sk_buff *skb)
{
        struct sock *sk = &tsk->sk;
        struct net *net = sock_net(sk);
        struct tipc_msg *hdr = buf_msg(skb);

        if (unlikely(msg_mcast(hdr)))
                return false;

        switch (sk->sk_state) {
        case TIPC_CONNECTING:
                /* Accept only ACK or NACK message */
                if (unlikely(!msg_connected(hdr)))
                        return false;

                if (unlikely(msg_errcode(hdr))) {
                        tipc_set_sk_state(sk, TIPC_DISCONNECTING);
                        sk->sk_err = ECONNREFUSED;
                        return true;
                }

                if (unlikely(!msg_isdata(hdr))) {
                        tipc_set_sk_state(sk, TIPC_DISCONNECTING);
                        sk->sk_err = EINVAL;
                        return true;
                }

                tipc_sk_finish_conn(tsk, msg_origport(hdr), msg_orignode(hdr));
                msg_set_importance(&tsk->phdr, msg_importance(hdr));

                /* If 'ACK+' message, add to socket receive queue */
                if (msg_data_sz(hdr))
                        return true;

                /* If empty 'ACK-' message, wake up sleeping connect() */
                if (waitqueue_active(sk_sleep(sk)))
                        wake_up_interruptible(sk_sleep(sk));

                /* 'ACK-' message is neither accepted nor rejected: */
                msg_set_dest_droppable(hdr, 1);
                return false;

        case TIPC_OPEN:
        case TIPC_DISCONNECTING:
                break;
        case TIPC_LISTEN:
                /* Accept only SYN message */
                if (!msg_connected(hdr) && !(msg_errcode(hdr)))
                        return true;
                break;
        case TIPC_ESTABLISHED:
                /* Accept only connection-based messages sent by peer */
                if (unlikely(!tsk_peer_msg(tsk, hdr)))
                        return false;

                if (unlikely(msg_errcode(hdr))) {
                        tipc_set_sk_state(sk, TIPC_DISCONNECTING);
                        /* Let timer expire on it's own */
                        tipc_node_remove_conn(net, tsk_peer_node(tsk),
                                              tsk->portid);
                        sk->sk_state_change(sk);
                }
                return true;
        default:
                pr_err("Unknown sk_state %u\n", sk->sk_state);
        }

        return false;
}

/**
 * rcvbuf_limit - get proper overload limit of socket receive queue
 * @sk: socket
 * @skb: message
 *
 * For connection oriented messages, irrespective of importance,
 * default queue limit is 2 MB.
 *
 * For connectionless messages, queue limits are based on message
 * importance as follows:
 *
 * TIPC_LOW_IMPORTANCE       (2 MB)
 * TIPC_MEDIUM_IMPORTANCE    (4 MB)
 * TIPC_HIGH_IMPORTANCE      (8 MB)
 * TIPC_CRITICAL_IMPORTANCE  (16 MB)
 *
 * Returns overload limit according to corresponding message importance
 */
static unsigned int rcvbuf_limit(struct sock *sk, struct sk_buff *skb)
{
        struct tipc_sock *tsk = tipc_sk(sk);
        struct tipc_msg *hdr = buf_msg(skb);

        if (unlikely(!msg_connected(hdr)))
                return sk->sk_rcvbuf << msg_importance(hdr);

        if (likely(tsk->peer_caps & TIPC_BLOCK_FLOWCTL))
                return sk->sk_rcvbuf;

        return FLOWCTL_MSG_LIM;
}

/**
 * filter_rcv - validate incoming message
 * @sk: socket
 * @skb: pointer to message.
 *
 * Enqueues message on receive queue if acceptable; optionally handles
 * disconnect indication for a connected socket.
 *
 * Called with socket lock already taken
 *
 * Returns true if message was added to socket receive queue, otherwise false
 */
static bool filter_rcv(struct sock *sk, struct sk_buff *skb,
                       struct sk_buff_head *xmitq)
{
        struct tipc_sock *tsk = tipc_sk(sk);
        struct tipc_msg *hdr = buf_msg(skb);
        unsigned int limit = rcvbuf_limit(sk, skb);
        int err = TIPC_OK;
        int usr = msg_user(hdr);
        u32 onode;

        if (unlikely(msg_user(hdr) == CONN_MANAGER)) {
                tipc_sk_proto_rcv(tsk, skb, xmitq);
                return false;
        }

        if (unlikely(usr == SOCK_WAKEUP)) {
                onode = msg_orignode(hdr);
                kfree_skb(skb);
                u32_del(&tsk->cong_links, onode);
                tsk->cong_link_cnt--;
                sk->sk_write_space(sk);
                return false;
        }

        /* Drop if illegal message type */
        if (unlikely(msg_type(hdr) > TIPC_DIRECT_MSG)) {
                kfree_skb(skb);
                return false;
        }

        /* Reject if wrong message type for current socket state */
        if (tipc_sk_type_connectionless(sk)) {
                if (msg_connected(hdr)) {
                        err = TIPC_ERR_NO_PORT;
                        goto reject;
                }
        } else if (unlikely(!filter_connect(tsk, skb))) {
                err = TIPC_ERR_NO_PORT;
                goto reject;
        }

        /* Reject message if there isn't room to queue it */
        if (unlikely(sk_rmem_alloc_get(sk) + skb->truesize >= limit)) {
                err = TIPC_ERR_OVERLOAD;
                goto reject;
        }

        /* Enqueue message */
        TIPC_SKB_CB(skb)->bytes_read = 0;
        __skb_queue_tail(&sk->sk_receive_queue, skb);
        skb_set_owner_r(skb, sk);

        sk->sk_data_ready(sk);
        return true;

reject:
        if (tipc_msg_reverse(tsk_own_node(tsk), &skb, err))
                __skb_queue_tail(xmitq, skb);
        return false;
}

/**
 * tipc_backlog_rcv - handle incoming message from backlog queue
 * @sk: socket
 * @skb: message
 *
 * Caller must hold socket lock
 *
 * Returns 0
 */
static int tipc_backlog_rcv(struct sock *sk, struct sk_buff *skb)
{
        unsigned int truesize = skb->truesize;
        struct sk_buff_head xmitq;
        u32 dnode, selector;

        __skb_queue_head_init(&xmitq);

        if (likely(filter_rcv(sk, skb, &xmitq))) {
                atomic_add(truesize, &tipc_sk(sk)->dupl_rcvcnt);
                return 0;
        }

        if (skb_queue_empty(&xmitq))
                return 0;

        /* Send response/rejected message */
        skb = __skb_dequeue(&xmitq);
        dnode = msg_destnode(buf_msg(skb));
        selector = msg_origport(buf_msg(skb));
        tipc_node_xmit_skb(sock_net(sk), skb, dnode, selector);
        return 0;
}

/**
 * tipc_sk_enqueue - extract all buffers with destination 'dport' from
 *                   inputq and try adding them to socket or backlog queue
 * @inputq: list of incoming buffers with potentially different destinations
 * @sk: socket where the buffers should be enqueued
 * @dport: port number for the socket
 *
 * Caller must hold socket lock
 */
static void tipc_sk_enqueue(struct sk_buff_head *inputq, struct sock *sk,
                            u32 dport, struct sk_buff_head *xmitq)
{
        unsigned long time_limit = jiffies + 2;
        struct sk_buff *skb;
        unsigned int lim;
        atomic_t *dcnt;
        u32 onode;

        while (skb_queue_len(inputq)) {
                if (unlikely(time_after_eq(jiffies, time_limit)))
                        return;

                skb = tipc_skb_dequeue(inputq, dport);
                if (unlikely(!skb))
                        return;

                /* Add message directly to receive queue if possible */
                if (!sock_owned_by_user(sk)) {
                        filter_rcv(sk, skb, xmitq);
                        continue;
                }

                /* Try backlog, compensating for double-counted bytes */
                dcnt = &tipc_sk(sk)->dupl_rcvcnt;
                if (!sk->sk_backlog.len)
                        atomic_set(dcnt, 0);
                lim = rcvbuf_limit(sk, skb) + atomic_read(dcnt);
                if (likely(!sk_add_backlog(sk, skb, lim)))
                        continue;

                /* Overload => reject message back to sender */
                onode = tipc_own_addr(sock_net(sk));
                if (tipc_msg_reverse(onode, &skb, TIPC_ERR_OVERLOAD))
                        __skb_queue_tail(xmitq, skb);
                break;
        }
}

/**
 * tipc_sk_rcv - handle a chain of incoming buffers
 * @inputq: buffer list containing the buffers
 * Consumes all buffers in list until inputq is empty
 * Note: may be called in multiple threads referring to the same queue
 */
void tipc_sk_rcv(struct net *net, struct sk_buff_head *inputq)
{
        struct sk_buff_head xmitq;
        u32 dnode, dport = 0;
        int err;
        struct tipc_sock *tsk;
        struct sock *sk;
        struct sk_buff *skb;

        __skb_queue_head_init(&xmitq);
        while (skb_queue_len(inputq)) {
                dport = tipc_skb_peek_port(inputq, dport);
                tsk = tipc_sk_lookup(net, dport);

                if (likely(tsk)) {
                        sk = &tsk->sk;
                        if (likely(spin_trylock_bh(&sk->sk_lock.slock))) {
                                tipc_sk_enqueue(inputq, sk, dport, &xmitq);
                                spin_unlock_bh(&sk->sk_lock.slock);
                        }
                        /* Send pending response/rejected messages, if any */
                        while ((skb = __skb_dequeue(&xmitq))) {
                                dnode = msg_destnode(buf_msg(skb));
                                tipc_node_xmit_skb(net, skb, dnode, dport);
                        }
                        sock_put(sk);
                        continue;
                }

                /* No destination socket => dequeue skb if still there */
                skb = tipc_skb_dequeue(inputq, dport);
                if (!skb)
                        return;

                /* Try secondary lookup if unresolved named message */
                err = TIPC_ERR_NO_PORT;
                if (tipc_msg_lookup_dest(net, skb, &err))
                        goto xmit;

                /* Prepare for message rejection */
                if (!tipc_msg_reverse(tipc_own_addr(net), &skb, err))
                        continue;
xmit:
                dnode = msg_destnode(buf_msg(skb));
                tipc_node_xmit_skb(net, skb, dnode, dport);
        }
}

static int tipc_wait_for_connect(struct socket *sock, long *timeo_p)
{
        DEFINE_WAIT_FUNC(wait, woken_wake_function);
        struct sock *sk = sock->sk;
        int done;

        do {
                int err = sock_error(sk);
                if (err)
                        return err;
                if (!*timeo_p)
                        return -ETIMEDOUT;
                if (signal_pending(current))
                        return sock_intr_errno(*timeo_p);

                add_wait_queue(sk_sleep(sk), &wait);
                done = sk_wait_event(sk, timeo_p,
                                     sk->sk_state != TIPC_CONNECTING, &wait);
                remove_wait_queue(sk_sleep(sk), &wait);
        } while (!done);
        return 0;
}

/**
 * tipc_connect - establish a connection to another TIPC port
 * @sock: socket structure
 * @dest: socket address for destination port
 * @destlen: size of socket address data structure
 * @flags: file-related flags associated with socket
 *
 * Returns 0 on success, errno otherwise
 */
static int tipc_connect(struct socket *sock, struct sockaddr *dest,
                        int destlen, int flags)
{
        struct sock *sk = sock->sk;
        struct tipc_sock *tsk = tipc_sk(sk);
        struct sockaddr_tipc *dst = (struct sockaddr_tipc *)dest;
        struct msghdr m = {NULL,};
        long timeout = (flags & O_NONBLOCK) ? 0 : tsk->conn_timeout;
        int previous;
        int res = 0;

        lock_sock(sk);

        /* DGRAM/RDM connect(), just save the destaddr */
        if (tipc_sk_type_connectionless(sk)) {
                if (dst->family == AF_UNSPEC) {
                        memset(&tsk->peer, 0, sizeof(struct sockaddr_tipc));
                } else if (destlen != sizeof(struct sockaddr_tipc)) {
                        res = -EINVAL;
                } else {
                        memcpy(&tsk->peer, dest, destlen);
                }
                goto exit;
        }

        /*
         * Reject connection attempt using multicast address
         *
         * Note: send_msg() validates the rest of the address fields,
         *       so there's no need to do it here
         */
        if (dst->addrtype == TIPC_ADDR_MCAST) {
                res = -EINVAL;
                goto exit;
        }

        previous = sk->sk_state;

        switch (sk->sk_state) {
        case TIPC_OPEN:
                /* Send a 'SYN-' to destination */
                m.msg_name = dest;
                m.msg_namelen = destlen;

                /* If connect is in non-blocking case, set MSG_DONTWAIT to
                 * indicate send_msg() is never blocked.
                 */
                if (!timeout)
                        m.msg_flags = MSG_DONTWAIT;

                res = __tipc_sendmsg(sock, &m, 0);
                if ((res < 0) && (res != -EWOULDBLOCK))
                        goto exit;

                /* Just entered TIPC_CONNECTING state; the only
                 * difference is that return value in non-blocking
                 * case is EINPROGRESS, rather than EALREADY.
                 */
                res = -EINPROGRESS;
                /* fall thru' */
        case TIPC_CONNECTING:
                if (!timeout) {
                        if (previous == TIPC_CONNECTING)
                                res = -EALREADY;
                        goto exit;
                }
                timeout = msecs_to_jiffies(timeout);
                /* Wait until an 'ACK' or 'RST' arrives, or a timeout occurs */
                res = tipc_wait_for_connect(sock, &timeout);
                break;
        case TIPC_ESTABLISHED:
                res = -EISCONN;
                break;
        default:
                res = -EINVAL;
        }

exit:
        release_sock(sk);
        return res;
}

/**
 * tipc_listen - allow socket to listen for incoming connections
 * @sock: socket structure
 * @len: (unused)
 *
 * Returns 0 on success, errno otherwise
 */
static int tipc_listen(struct socket *sock, int len)
{
        struct sock *sk = sock->sk;
        int res;

        lock_sock(sk);
        res = tipc_set_sk_state(sk, TIPC_LISTEN);
        release_sock(sk);

        return res;
}

static int tipc_wait_for_accept(struct socket *sock, long timeo)
{
        struct sock *sk = sock->sk;
        DEFINE_WAIT(wait);
        int err;

        /* True wake-one mechanism for incoming connections: only
         * one process gets woken up, not the 'whole herd'.
         * Since we do not 'race & poll' for established sockets
         * anymore, the common case will execute the loop only once.
        */
        for (;;) {
                prepare_to_wait_exclusive(sk_sleep(sk), &wait,
                                          TASK_INTERRUPTIBLE);
                if (timeo && skb_queue_empty(&sk->sk_receive_queue)) {
                        release_sock(sk);
                        timeo = schedule_timeout(timeo);
                        lock_sock(sk);
                }
                err = 0;
                if (!skb_queue_empty(&sk->sk_receive_queue))
                        break;
                err = -EAGAIN;
                if (!timeo)
                        break;
                err = sock_intr_errno(timeo);
                if (signal_pending(current))
                        break;
        }
        finish_wait(sk_sleep(sk), &wait);
        return err;
}

/**
 * tipc_accept - wait for connection request
 * @sock: listening socket
 * @newsock: new socket that is to be connected
 * @flags: file-related flags associated with socket
 *
 * Returns 0 on success, errno otherwise
 */
static int tipc_accept(struct socket *sock, struct socket *new_sock, int flags,
                       bool kern)
{
        struct sock *new_sk, *sk = sock->sk;
        struct sk_buff *buf;
        struct tipc_sock *new_tsock;
        struct tipc_msg *msg;
        long timeo;
        int res;

        lock_sock(sk);

        if (sk->sk_state != TIPC_LISTEN) {
                res = -EINVAL;
                goto exit;
        }
        timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
        res = tipc_wait_for_accept(sock, timeo);
        if (res)
                goto exit;

        buf = skb_peek(&sk->sk_receive_queue);

        res = tipc_sk_create(sock_net(sock->sk), new_sock, 0, kern);
        if (res)
                goto exit;
        security_sk_clone(sock->sk, new_sock->sk);

        new_sk = new_sock->sk;
        new_tsock = tipc_sk(new_sk);
        msg = buf_msg(buf);

        /* we lock on new_sk; but lockdep sees the lock on sk */
        lock_sock_nested(new_sk, SINGLE_DEPTH_NESTING);

        /*
         * Reject any stray messages received by new socket
         * before the socket lock was taken (very, very unlikely)
         */
        tsk_rej_rx_queue(new_sk);

        /* Connect new socket to it's peer */
        tipc_sk_finish_conn(new_tsock, msg_origport(msg), msg_orignode(msg));

        tsk_set_importance(new_tsock, msg_importance(msg));
        if (msg_named(msg)) {
                new_tsock->conn_type = msg_nametype(msg);
                new_tsock->conn_instance = msg_nameinst(msg);
        }

        /*
         * Respond to 'SYN-' by discarding it & returning 'ACK'-.
         * Respond to 'SYN+' by queuing it on new socket.
         */
        if (!msg_data_sz(msg)) {
                struct msghdr m = {NULL,};

                tsk_advance_rx_queue(sk);
                __tipc_sendstream(new_sock, &m, 0);
        } else {
                __skb_dequeue(&sk->sk_receive_queue);
                __skb_queue_head(&new_sk->sk_receive_queue, buf);
                skb_set_owner_r(buf, new_sk);
        }
        release_sock(new_sk);
exit:
        release_sock(sk);
        return res;
}

/**
 * tipc_shutdown - shutdown socket connection
 * @sock: socket structure
 * @how: direction to close (must be SHUT_RDWR)
 *
 * Terminates connection (if necessary), then purges socket's receive queue.
 *
 * Returns 0 on success, errno otherwise
 */
static int tipc_shutdown(struct socket *sock, int how)
{
        struct sock *sk = sock->sk;
        int res;

        if (how != SHUT_RDWR)
                return -EINVAL;

        lock_sock(sk);

        __tipc_shutdown(sock, TIPC_CONN_SHUTDOWN);
        sk->sk_shutdown = SEND_SHUTDOWN;

        if (sk->sk_state == TIPC_DISCONNECTING) {
                /* Discard any unreceived messages */
                __skb_queue_purge(&sk->sk_receive_queue);

                /* Wake up anyone sleeping in poll */
                sk->sk_state_change(sk);
                res = 0;
        } else {
                res = -ENOTCONN;
        }

        release_sock(sk);
        return res;
}

static void tipc_sk_timeout(unsigned long data)
{
        struct tipc_sock *tsk = (struct tipc_sock *)data;
        struct sock *sk = &tsk->sk;
        struct sk_buff *skb = NULL;
        u32 peer_port, peer_node;
        u32 own_node = tsk_own_node(tsk);

        bh_lock_sock(sk);
        if (!tipc_sk_connected(sk)) {
                bh_unlock_sock(sk);
                goto exit;
        }
        peer_port = tsk_peer_port(tsk);
        peer_node = tsk_peer_node(tsk);

        if (tsk->probe_unacked) {
                if (!sock_owned_by_user(sk)) {
                        tipc_set_sk_state(sk, TIPC_DISCONNECTING);
                        tipc_node_remove_conn(sock_net(sk), tsk_peer_node(tsk),
                                              tsk_peer_port(tsk));
                        sk->sk_state_change(sk);
                } else {
                        /* Try again later */
                        sk_reset_timer(sk, &sk->sk_timer, (HZ / 20));
                }

                bh_unlock_sock(sk);
                goto exit;
        }

        skb = tipc_msg_create(CONN_MANAGER, CONN_PROBE,
                              INT_H_SIZE, 0, peer_node, own_node,
                              peer_port, tsk->portid, TIPC_OK);
        tsk->probe_unacked = true;
        sk_reset_timer(sk, &sk->sk_timer, jiffies + CONN_PROBING_INTERVAL);
        bh_unlock_sock(sk);
        if (skb)
                tipc_node_xmit_skb(sock_net(sk), skb, peer_node, tsk->portid);
exit:
        sock_put(sk);
}

static int tipc_sk_publish(struct tipc_sock *tsk, uint scope,
                           struct tipc_name_seq const *seq)
{
        struct sock *sk = &tsk->sk;
        struct net *net = sock_net(sk);
        struct publication *publ;
        u32 key;

        if (tipc_sk_connected(sk))
                return -EINVAL;
        key = tsk->portid + tsk->pub_count + 1;
        if (key == tsk->portid)
                return -EADDRINUSE;

        publ = tipc_nametbl_publish(net, seq->type, seq->lower, seq->upper,
                                    scope, tsk->portid, key);
        if (unlikely(!publ))
                return -EINVAL;

        list_add(&publ->pport_list, &tsk->publications);
        tsk->pub_count++;
        tsk->published = 1;
        return 0;
}

static int tipc_sk_withdraw(struct tipc_sock *tsk, uint scope,
                            struct tipc_name_seq const *seq)
{
        struct net *net = sock_net(&tsk->sk);
        struct publication *publ;
        struct publication *safe;
        int rc = -EINVAL;

        list_for_each_entry_safe(publ, safe, &tsk->publications, pport_list) {
                if (seq) {
                        if (publ->scope != scope)
                                continue;
                        if (publ->type != seq->type)
                                continue;
                        if (publ->lower != seq->lower)
                                continue;
                        if (publ->upper != seq->upper)
                                break;
                        tipc_nametbl_withdraw(net, publ->type, publ->lower,
                                              publ->ref, publ->key);
                        rc = 0;
                        break;
                }
                tipc_nametbl_withdraw(net, publ->type, publ->lower,
                                      publ->ref, publ->key);
                rc = 0;
        }
        if (list_empty(&tsk->publications))
                tsk->published = 0;
        return rc;
}

/* tipc_sk_reinit: set non-zero address in all existing sockets
 *                 when we go from standalone to network mode.
 */
void tipc_sk_reinit(struct net *net)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct rhashtable_iter iter;
        struct tipc_sock *tsk;
        struct tipc_msg *msg;

        rhashtable_walk_enter(&tn->sk_rht, &iter);

        do {
                tsk = ERR_PTR(rhashtable_walk_start(&iter));
                if (tsk)
                        continue;

                while ((tsk = rhashtable_walk_next(&iter)) && !IS_ERR(tsk)) {
                        spin_lock_bh(&tsk->sk.sk_lock.slock);
                        msg = &tsk->phdr;
                        msg_set_prevnode(msg, tn->own_addr);
                        msg_set_orignode(msg, tn->own_addr);
                        spin_unlock_bh(&tsk->sk.sk_lock.slock);
                }

                rhashtable_walk_stop(&iter);
        } while (tsk == ERR_PTR(-EAGAIN));
}

static struct tipc_sock *tipc_sk_lookup(struct net *net, u32 portid)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct tipc_sock *tsk;

        rcu_read_lock();
        tsk = rhashtable_lookup_fast(&tn->sk_rht, &portid, tsk_rht_params);
        if (tsk)
                sock_hold(&tsk->sk);
        rcu_read_unlock();

        return tsk;
}

static int tipc_sk_insert(struct tipc_sock *tsk)
{
        struct sock *sk = &tsk->sk;
        struct net *net = sock_net(sk);
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        u32 remaining = (TIPC_MAX_PORT - TIPC_MIN_PORT) + 1;
        u32 portid = prandom_u32() % remaining + TIPC_MIN_PORT;

        while (remaining--) {
                portid++;
                if ((portid < TIPC_MIN_PORT) || (portid > TIPC_MAX_PORT))
                        portid = TIPC_MIN_PORT;
                tsk->portid = portid;
                sock_hold(&tsk->sk);
                if (!rhashtable_lookup_insert_fast(&tn->sk_rht, &tsk->node,
                                                   tsk_rht_params))
                        return 0;
                sock_put(&tsk->sk);
        }

        return -1;
}

static void tipc_sk_remove(struct tipc_sock *tsk)
{
        struct sock *sk = &tsk->sk;
        struct tipc_net *tn = net_generic(sock_net(sk), tipc_net_id);

        if (!rhashtable_remove_fast(&tn->sk_rht, &tsk->node, tsk_rht_params)) {
                WARN_ON(atomic_read(&sk->sk_refcnt) == 1);
                __sock_put(sk);
        }
}

static const struct rhashtable_params tsk_rht_params = {
        .nelem_hint = 192,
        .head_offset = offsetof(struct tipc_sock, node),
        .key_offset = offsetof(struct tipc_sock, portid),
        .key_len = sizeof(u32), /* portid */
        .max_size = 1048576,
        .min_size = 256,
        .automatic_shrinking = true,
};

int tipc_sk_rht_init(struct net *net)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);

        return rhashtable_init(&tn->sk_rht, &tsk_rht_params);
}

void tipc_sk_rht_destroy(struct net *net)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);

        /* Wait for socket readers to complete */
        synchronize_net();

        rhashtable_destroy(&tn->sk_rht);
}

/**
 * tipc_setsockopt - set socket option
 * @sock: socket structure
 * @lvl: option level
 * @opt: option identifier
 * @ov: pointer to new option value
 * @ol: length of option value
 *
 * For stream sockets only, accepts and ignores all IPPROTO_TCP options
 * (to ease compatibility).
 *
 * Returns 0 on success, errno otherwise
 */
static int tipc_setsockopt(struct socket *sock, int lvl, int opt,
                           char __user *ov, unsigned int ol)
{
        struct sock *sk = sock->sk;
        struct tipc_sock *tsk = tipc_sk(sk);
        u32 value = 0;
        int res = 0;

        if ((lvl == IPPROTO_TCP) && (sock->type == SOCK_STREAM))
                return 0;
        if (lvl != SOL_TIPC)
                return -ENOPROTOOPT;

        switch (opt) {
        case TIPC_IMPORTANCE:
        case TIPC_SRC_DROPPABLE:
        case TIPC_DEST_DROPPABLE:
        case TIPC_CONN_TIMEOUT:
                if (ol < sizeof(value))
                        return -EINVAL;
                res = get_user(value, (u32 __user *)ov);
                if (res)
                        return res;
                break;
        default:
                if (ov || ol)
                        return -EINVAL;
        }

        lock_sock(sk);

        switch (opt) {
        case TIPC_IMPORTANCE:
                res = tsk_set_importance(tsk, value);
                break;
        case TIPC_SRC_DROPPABLE:
                if (sock->type != SOCK_STREAM)
                        tsk_set_unreliable(tsk, value);
                else
                        res = -ENOPROTOOPT;
                break;
        case TIPC_DEST_DROPPABLE:
                tsk_set_unreturnable(tsk, value);
                break;
        case TIPC_CONN_TIMEOUT:
                tipc_sk(sk)->conn_timeout = value;
                break;
        case TIPC_MCAST_BROADCAST:
                tsk->mc_method.rcast = false;
                tsk->mc_method.mandatory = true;
                break;
        case TIPC_MCAST_REPLICAST:
                tsk->mc_method.rcast = true;
                tsk->mc_method.mandatory = true;
                break;
        default:
                res = -EINVAL;
        }

        release_sock(sk);

        return res;
}

/**
 * tipc_getsockopt - get socket option
 * @sock: socket structure
 * @lvl: option level
 * @opt: option identifier
 * @ov: receptacle for option value
 * @ol: receptacle for length of option value
 *
 * For stream sockets only, returns 0 length result for all IPPROTO_TCP options
 * (to ease compatibility).
 *
 * Returns 0 on success, errno otherwise
 */
static int tipc_getsockopt(struct socket *sock, int lvl, int opt,
                           char __user *ov, int __user *ol)
{
        struct sock *sk = sock->sk;
        struct tipc_sock *tsk = tipc_sk(sk);
        int len;
        u32 value;
        int res;

        if ((lvl == IPPROTO_TCP) && (sock->type == SOCK_STREAM))
                return put_user(0, ol);
        if (lvl != SOL_TIPC)
                return -ENOPROTOOPT;
        res = get_user(len, ol);
        if (res)
                return res;

        lock_sock(sk);

        switch (opt) {
        case TIPC_IMPORTANCE:
                value = tsk_importance(tsk);
                break;
        case TIPC_SRC_DROPPABLE:
                value = tsk_unreliable(tsk);
                break;
        case TIPC_DEST_DROPPABLE:
                value = tsk_unreturnable(tsk);
                break;
        case TIPC_CONN_TIMEOUT:
                value = tsk->conn_timeout;
                /* no need to set "res", since already 0 at this point */
                break;
        case TIPC_NODE_RECVQ_DEPTH:
                value = 0; /* was tipc_queue_size, now obsolete */
                break;
        case TIPC_SOCK_RECVQ_DEPTH:
                value = skb_queue_len(&sk->sk_receive_queue);
                break;
        default:
                res = -EINVAL;
        }

        release_sock(sk);

        if (res)
                return res;     /* "get" failed */

        if (len < sizeof(value))
                return -EINVAL;

        if (copy_to_user(ov, &value, sizeof(value)))
                return -EFAULT;

        return put_user(sizeof(value), ol);
}

static int tipc_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
        struct sock *sk = sock->sk;
        struct tipc_sioc_ln_req lnr;
        void __user *argp = (void __user *)arg;

        switch (cmd) {
        case SIOCGETLINKNAME:
                if (copy_from_user(&lnr, argp, sizeof(lnr)))
                        return -EFAULT;
                if (!tipc_node_get_linkname(sock_net(sk),
                                            lnr.bearer_id & 0xffff, lnr.peer,
                                            lnr.linkname, TIPC_MAX_LINK_NAME)) {
                        if (copy_to_user(argp, &lnr, sizeof(lnr)))
                                return -EFAULT;
                        return 0;
                }
                return -EADDRNOTAVAIL;
        default:
                return -ENOIOCTLCMD;
        }
}

/* Protocol switches for the various types of TIPC sockets */

static const struct proto_ops msg_ops = {
        .owner          = THIS_MODULE,
        .family         = AF_TIPC,
        .release        = tipc_release,
        .bind           = tipc_bind,
        .connect        = tipc_connect,
        .socketpair     = sock_no_socketpair,
        .accept         = sock_no_accept,
        .getname        = tipc_getname,
        .poll           = tipc_poll,
        .ioctl          = tipc_ioctl,
        .listen         = sock_no_listen,
        .shutdown       = tipc_shutdown,
        .setsockopt     = tipc_setsockopt,
        .getsockopt     = tipc_getsockopt,
        .sendmsg        = tipc_sendmsg,
        .recvmsg        = tipc_recvmsg,
        .mmap           = sock_no_mmap,
        .sendpage       = sock_no_sendpage
};

static const struct proto_ops packet_ops = {
        .owner          = THIS_MODULE,
        .family         = AF_TIPC,
        .release        = tipc_release,
        .bind           = tipc_bind,
        .connect        = tipc_connect,
        .socketpair     = sock_no_socketpair,
        .accept         = tipc_accept,
        .getname        = tipc_getname,
        .poll           = tipc_poll,
        .ioctl          = tipc_ioctl,
        .listen         = tipc_listen,
        .shutdown       = tipc_shutdown,
        .setsockopt     = tipc_setsockopt,
        .getsockopt     = tipc_getsockopt,
        .sendmsg        = tipc_send_packet,
        .recvmsg        = tipc_recvmsg,
        .mmap           = sock_no_mmap,
        .sendpage       = sock_no_sendpage
};

static const struct proto_ops stream_ops = {
        .owner          = THIS_MODULE,
        .family         = AF_TIPC,
        .release        = tipc_release,
        .bind           = tipc_bind,
        .connect        = tipc_connect,
        .socketpair     = sock_no_socketpair,
        .accept         = tipc_accept,
        .getname        = tipc_getname,
        .poll           = tipc_poll,
        .ioctl          = tipc_ioctl,
        .listen         = tipc_listen,
        .shutdown       = tipc_shutdown,
        .setsockopt     = tipc_setsockopt,
        .getsockopt     = tipc_getsockopt,
        .sendmsg        = tipc_sendstream,
        .recvmsg        = tipc_recv_stream,
        .mmap           = sock_no_mmap,
        .sendpage       = sock_no_sendpage
};

static const struct net_proto_family tipc_family_ops = {
        .owner          = THIS_MODULE,
        .family         = AF_TIPC,
        .create         = tipc_sk_create
};

static struct proto tipc_proto = {
        .name           = "TIPC",
        .owner          = THIS_MODULE,
        .obj_size       = sizeof(struct tipc_sock),
        .sysctl_rmem    = sysctl_tipc_rmem
};

/**
 * tipc_socket_init - initialize TIPC socket interface
 *
 * Returns 0 on success, errno otherwise
 */
int tipc_socket_init(void)
{
        int res;

        res = proto_register(&tipc_proto, 1);
        if (res) {
                pr_err("Failed to register TIPC protocol type\n");
                goto out;
        }

        res = sock_register(&tipc_family_ops);
        if (res) {
                pr_err("Failed to register TIPC socket type\n");
                proto_unregister(&tipc_proto);
                goto out;
        }
 out:
        return res;
}

/**
 * tipc_socket_stop - stop TIPC socket interface
 */
void tipc_socket_stop(void)
{
        sock_unregister(tipc_family_ops.family);
        proto_unregister(&tipc_proto);
}

/* Caller should hold socket lock for the passed tipc socket. */
static int __tipc_nl_add_sk_con(struct sk_buff *skb, struct tipc_sock *tsk)
{
        u32 peer_node;
        u32 peer_port;
        struct nlattr *nest;

        peer_node = tsk_peer_node(tsk);
        peer_port = tsk_peer_port(tsk);

        nest = nla_nest_start(skb, TIPC_NLA_SOCK_CON);

        if (nla_put_u32(skb, TIPC_NLA_CON_NODE, peer_node))
                goto msg_full;
        if (nla_put_u32(skb, TIPC_NLA_CON_SOCK, peer_port))
                goto msg_full;

        if (tsk->conn_type != 0) {
                if (nla_put_flag(skb, TIPC_NLA_CON_FLAG))
                        goto msg_full;
                if (nla_put_u32(skb, TIPC_NLA_CON_TYPE, tsk->conn_type))
                        goto msg_full;
                if (nla_put_u32(skb, TIPC_NLA_CON_INST, tsk->conn_instance))
                        goto msg_full;
        }
        nla_nest_end(skb, nest);

        return 0;

msg_full:
        nla_nest_cancel(skb, nest);

        return -EMSGSIZE;
}

/* Caller should hold socket lock for the passed tipc socket. */
static int __tipc_nl_add_sk(struct sk_buff *skb, struct netlink_callback *cb,
                            struct tipc_sock *tsk)
{
        int err;
        void *hdr;
        struct nlattr *attrs;
        struct net *net = sock_net(skb->sk);
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct sock *sk = &tsk->sk;

        hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
                          &tipc_genl_family, NLM_F_MULTI, TIPC_NL_SOCK_GET);
        if (!hdr)
                goto msg_cancel;

        attrs = nla_nest_start(skb, TIPC_NLA_SOCK);
        if (!attrs)
                goto genlmsg_cancel;
        if (nla_put_u32(skb, TIPC_NLA_SOCK_REF, tsk->portid))
                goto attr_msg_cancel;
        if (nla_put_u32(skb, TIPC_NLA_SOCK_ADDR, tn->own_addr))
                goto attr_msg_cancel;

        if (tipc_sk_connected(sk)) {
                err = __tipc_nl_add_sk_con(skb, tsk);
                if (err)
                        goto attr_msg_cancel;
        } else if (!list_empty(&tsk->publications)) {
                if (nla_put_flag(skb, TIPC_NLA_SOCK_HAS_PUBL))
                        goto attr_msg_cancel;
        }
        nla_nest_end(skb, attrs);
        genlmsg_end(skb, hdr);

        return 0;

attr_msg_cancel:
        nla_nest_cancel(skb, attrs);
genlmsg_cancel:
        genlmsg_cancel(skb, hdr);
msg_cancel:
        return -EMSGSIZE;
}

int tipc_nl_sk_dump(struct sk_buff *skb, struct netlink_callback *cb)
{
        int err;
        struct tipc_sock *tsk;
        const struct bucket_table *tbl;
        struct rhash_head *pos;
        struct net *net = sock_net(skb->sk);
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        u32 tbl_id = cb->args[0];
        u32 prev_portid = cb->args[1];

        rcu_read_lock();
        tbl = rht_dereference_rcu((&tn->sk_rht)->tbl, &tn->sk_rht);
        for (; tbl_id < tbl->size; tbl_id++) {
                rht_for_each_entry_rcu(tsk, pos, tbl, tbl_id, node) {
                        spin_lock_bh(&tsk->sk.sk_lock.slock);
                        if (prev_portid && prev_portid != tsk->portid) {
                                spin_unlock_bh(&tsk->sk.sk_lock.slock);
                                continue;
                        }

                        err = __tipc_nl_add_sk(skb, cb, tsk);
                        if (err) {
                                prev_portid = tsk->portid;
                                spin_unlock_bh(&tsk->sk.sk_lock.slock);
                                goto out;
                        }
                        prev_portid = 0;
                        spin_unlock_bh(&tsk->sk.sk_lock.slock);
                }
        }
out:
        rcu_read_unlock();
        cb->args[0] = tbl_id;
        cb->args[1] = prev_portid;

        return skb->len;
}

/* Caller should hold socket lock for the passed tipc socket. */
static int __tipc_nl_add_sk_publ(struct sk_buff *skb,
                                 struct netlink_callback *cb,
                                 struct publication *publ)
{
        void *hdr;
        struct nlattr *attrs;

        hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
                          &tipc_genl_family, NLM_F_MULTI, TIPC_NL_PUBL_GET);
        if (!hdr)
                goto msg_cancel;

        attrs = nla_nest_start(skb, TIPC_NLA_PUBL);
        if (!attrs)
                goto genlmsg_cancel;

        if (nla_put_u32(skb, TIPC_NLA_PUBL_KEY, publ->key))
                goto attr_msg_cancel;
        if (nla_put_u32(skb, TIPC_NLA_PUBL_TYPE, publ->type))
                goto attr_msg_cancel;
        if (nla_put_u32(skb, TIPC_NLA_PUBL_LOWER, publ->lower))
                goto attr_msg_cancel;
        if (nla_put_u32(skb, TIPC_NLA_PUBL_UPPER, publ->upper))
                goto attr_msg_cancel;

        nla_nest_end(skb, attrs);
        genlmsg_end(skb, hdr);

        return 0;

attr_msg_cancel:
        nla_nest_cancel(skb, attrs);
genlmsg_cancel:
        genlmsg_cancel(skb, hdr);
msg_cancel:
        return -EMSGSIZE;
}

/* Caller should hold socket lock for the passed tipc socket. */
static int __tipc_nl_list_sk_publ(struct sk_buff *skb,
                                  struct netlink_callback *cb,
                                  struct tipc_sock *tsk, u32 *last_publ)
{
        int err;
        struct publication *p;

        if (*last_publ) {
                list_for_each_entry(p, &tsk->publications, pport_list) {
                        if (p->key == *last_publ)
                                break;
                }
                if (p->key != *last_publ) {
                        /* We never set seq or call nl_dump_check_consistent()
                         * this means that setting prev_seq here will cause the
                         * consistence check to fail in the netlink callback
                         * handler. Resulting in the last NLMSG_DONE message
                         * having the NLM_F_DUMP_INTR flag set.
                         */
                        cb->prev_seq = 1;
                        *last_publ = 0;
                        return -EPIPE;
                }
        } else {
                p = list_first_entry(&tsk->publications, struct publication,
                                     pport_list);
        }

        list_for_each_entry_from(p, &tsk->publications, pport_list) {
                err = __tipc_nl_add_sk_publ(skb, cb, p);
                if (err) {
                        *last_publ = p->key;
                        return err;
                }
        }
        *last_publ = 0;

        return 0;
}

int tipc_nl_publ_dump(struct sk_buff *skb, struct netlink_callback *cb)
{
        int err;
        u32 tsk_portid = cb->args[0];
        u32 last_publ = cb->args[1];
        u32 done = cb->args[2];
        struct net *net = sock_net(skb->sk);
        struct tipc_sock *tsk;

        if (!tsk_portid) {
                struct nlattr **attrs;
                struct nlattr *sock[TIPC_NLA_SOCK_MAX + 1];

                err = tipc_nlmsg_parse(cb->nlh, &attrs);
                if (err)
                        return err;

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

                err = nla_parse_nested(sock, TIPC_NLA_SOCK_MAX,
                                       attrs[TIPC_NLA_SOCK],
                                       tipc_nl_sock_policy);
                if (err)
                        return err;

                if (!sock[TIPC_NLA_SOCK_REF])
                        return -EINVAL;

                tsk_portid = nla_get_u32(sock[TIPC_NLA_SOCK_REF]);
        }

        if (done)
                return 0;

        tsk = tipc_sk_lookup(net, tsk_portid);
        if (!tsk)
                return -EINVAL;

        lock_sock(&tsk->sk);
        err = __tipc_nl_list_sk_publ(skb, cb, tsk, &last_publ);
        if (!err)
                done = 1;
        release_sock(&tsk->sk);
        sock_put(&tsk->sk);

        cb->args[0] = tsk_portid;
        cb->args[1] = last_publ;
        cb->args[2] = done;

        return skb->len;
}