af_inet.c

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/*
 * INET     An implementation of the TCP/IP protocol suite for the LINUX
 *      operating system.  INET is implemented using the  BSD Socket
 *      interface as the means of communication with the user level.
 *
 *      PF_INET protocol family socket handler.
 *
 * Authors: Ross Biro
 *      Fred N. van Kempen, <[email protected]>
 *      Florian La Roche, <[email protected]>
 *      Alan Cox, <[email protected]>
 *
 * Changes (see also sock.c)
 *
 *      piggy,
 *      Karl Knutson    :   Socket protocol table
 *      A.N.Kuznetsov   :   Socket death error in accept().
 *      John Richardson :   Fix non blocking error in connect()
 *                  so sockets that fail to connect
 *                  don't return -EINPROGRESS.
 *      Alan Cox    :   Asynchronous I/O support
 *      Alan Cox    :   Keep correct socket pointer on sock
 *                  structures
 *                  when accept() ed
 *      Alan Cox    :   Semantics of SO_LINGER aren't state
 *                  moved to close when you look carefully.
 *                  With this fixed and the accept bug fixed
 *                  some RPC stuff seems happier.
 *      Niibe Yutaka    :   4.4BSD style write async I/O
 *      Alan Cox,
 *      Tony Gale   :   Fixed reuse semantics.
 *      Alan Cox    :   bind() shouldn't abort existing but dead
 *                  sockets. Stops FTP netin:.. I hope.
 *      Alan Cox    :   bind() works correctly for RAW sockets.
 *                  Note that FreeBSD at least was broken
 *                  in this respect so be careful with
 *                  compatibility tests...
 *      Alan Cox    :   routing cache support
 *      Alan Cox    :   memzero the socket structure for
 *                  compactness.
 *      Matt Day    :   nonblock connect error handler
 *      Alan Cox    :   Allow large numbers of pending sockets
 *                  (eg for big web sites), but only if
 *                  specifically application requested.
 *      Alan Cox    :   New buffering throughout IP. Used
 *                  dumbly.
 *      Alan Cox    :   New buffering now used smartly.
 *      Alan Cox    :   BSD rather than common sense
 *                  interpretation of listen.
 *      Germano Caronni :   Assorted small races.
 *      Alan Cox    :   sendmsg/recvmsg basic support.
 *      Alan Cox    :   Only sendmsg/recvmsg now supported.
 *      Alan Cox    :   Locked down bind (see security list).
 *      Alan Cox    :   Loosened bind a little.
 *      Mike McLagan    :   ADD/DEL DLCI Ioctls
 *  Willy Konynenberg   :   Transparent proxying support.
 *      David S. Miller :   New socket lookup architecture.
 *                  Some other random speedups.
 *      Cyrus Durgin    :   Cleaned up file for kmod hacks.
 *      Andi Kleen  :   Fix inet_stream_connect TCP race.
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */

#define pr_fmt(fmt) "IPv4: " fmt

#include <linux/err.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/capability.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/netfilter_ipv4.h>
#include <linux/random.h>
#include <linux/slab.h>

#include <asm/uaccess.h>

#include <linux/inet.h>
#include <linux/igmp.h>
#include <linux/inetdevice.h>
#include <linux/netdevice.h>
#include <net/checksum.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <net/arp.h>
#include <net/route.h>
#include <net/ip_fib.h>
#include <net/inet_connection_sock.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <net/udplite.h>
#include <net/ping.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/raw.h>
#include <net/icmp.h>
#include <net/ipip.h>
#include <net/inet_common.h>
#include <net/xfrm.h>
#include <net/net_namespace.h>
#ifdef CONFIG_IP_MROUTE
#include <linux/mroute.h>
#endif


/* The inetsw table contains everything that inet_create needs to
 * build a new socket.
 */
static struct list_head inetsw[SOCK_MAX];
static DEFINE_SPINLOCK(inetsw_lock);

struct ipv4_config ipv4_config;
EXPORT_SYMBOL(ipv4_config);

/* New destruction routine */

void inet_sock_destruct(struct sock *sk)
{
    struct inet_sock *inet = inet_sk(sk);

    __skb_queue_purge(&sk->sk_receive_queue);
    __skb_queue_purge(&sk->sk_error_queue);

    sk_mem_reclaim(sk);

    if (sk->sk_type == SOCK_STREAM && sk->sk_state != TCP_CLOSE) {
        pr_err("Attempt to release TCP socket in state %d %p\n",
               sk->sk_state, sk);
        return;
    }
    if (!sock_flag(sk, SOCK_DEAD)) {
        pr_err("Attempt to release alive inet socket %p\n", sk);
        return;
    }

    WARN_ON(atomic_read(&sk->sk_rmem_alloc));
    WARN_ON(atomic_read(&sk->sk_wmem_alloc));
    WARN_ON(sk->sk_wmem_queued);
    WARN_ON(sk->sk_forward_alloc);

    kfree(rcu_dereference_protected(inet->inet_opt, 1));
    dst_release(rcu_dereference_check(sk->sk_dst_cache, 1));
    dst_release(sk->sk_rx_dst);
    sk_refcnt_debug_dec(sk);
}
EXPORT_SYMBOL(inet_sock_destruct);

/*
 *  The routines beyond this point handle the behaviour of an AF_INET
 *  socket object. Mostly it punts to the subprotocols of IP to do
 *  the work.
 */

/*
 *  Automatically bind an unbound socket.
 */

static int inet_autobind(struct sock *sk)
{
    struct inet_sock *inet;
    /* We may need to bind the socket. */
    lock_sock(sk);
    inet = inet_sk(sk);
    if (!inet->inet_num) {
        if (sk->sk_prot->get_port(sk, 0)) {
            release_sock(sk);
            return -EAGAIN;
        }
        inet->inet_sport = htons(inet->inet_num);
    }
    release_sock(sk);
    return 0;
}

/*
 *  Move a socket into listening state.
 */
int inet_listen(struct socket *sock, int backlog)
{
    struct sock *sk = sock->sk;
    unsigned char old_state;
    int err;

    lock_sock(sk);

    err = -EINVAL;
    if (sock->state != SS_UNCONNECTED || sock->type != SOCK_STREAM)
        goto out;

    old_state = sk->sk_state;
    if (!((1 << old_state) & (TCPF_CLOSE | TCPF_LISTEN)))
        goto out;

    /* Really, if the socket is already in listen state
     * we can only allow the backlog to be adjusted.
     */
    if (old_state != TCP_LISTEN) {
        /* Check special setups for testing purpose to enable TFO w/o
         * requiring TCP_FASTOPEN sockopt.
         * Note that only TCP sockets (SOCK_STREAM) will reach here.
         * Also fastopenq may already been allocated because this
         * socket was in TCP_LISTEN state previously but was
         * shutdown() (rather than close()).
         */
        if ((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) != 0 &&
            inet_csk(sk)->icsk_accept_queue.fastopenq == NULL) {
            if ((sysctl_tcp_fastopen & TFO_SERVER_WO_SOCKOPT1) != 0)
                err = fastopen_init_queue(sk, backlog);
            else if ((sysctl_tcp_fastopen &
                  TFO_SERVER_WO_SOCKOPT2) != 0)
                err = fastopen_init_queue(sk,
                    ((uint)sysctl_tcp_fastopen) >> 16);
            else
                err = 0;
            if (err)
                goto out;
        }
        err = inet_csk_listen_start(sk, backlog);
        if (err)
            goto out;
    }
    sk->sk_max_ack_backlog = backlog;
    err = 0;

out:
    release_sock(sk);
    return err;
}
EXPORT_SYMBOL(inet_listen);

u32 inet_ehash_secret __read_mostly;
EXPORT_SYMBOL(inet_ehash_secret);

/*
 * inet_ehash_secret must be set exactly once
 */
void build_ehash_secret(void)
{
    u32 rnd;

    do {
        get_random_bytes(&rnd, sizeof(rnd));
    } while (rnd == 0);

    cmpxchg(&inet_ehash_secret, 0, rnd);
}
EXPORT_SYMBOL(build_ehash_secret);

static inline int inet_netns_ok(struct net *net, __u8 protocol)
{
    const struct net_protocol *ipprot;

    if (net_eq(net, &init_net))
        return 1;

    ipprot = rcu_dereference(inet_protos[protocol]);
    if (ipprot == NULL) {
        /* raw IP is OK */
        return 1;
    }
    return ipprot->netns_ok;
}

/*
 *  Create an inet socket.
 */

static int inet_create(struct net *net, struct socket *sock, int protocol,
               int kern)
{
    struct sock *sk;
    struct inet_protosw *answer;
    struct inet_sock *inet;
    struct proto *answer_prot;
    unsigned char answer_flags;
    char answer_no_check;
    int try_loading_module = 0;
    int err;

    if (unlikely(!inet_ehash_secret))
        if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM)
            build_ehash_secret();

    sock->state = SS_UNCONNECTED;

    /* Look for the requested type/protocol pair. */
lookup_protocol:
    err = -ESOCKTNOSUPPORT;
    rcu_read_lock();
    list_for_each_entry_rcu(answer, &inetsw[sock->type], list) {

        err = 0;
        /* Check the non-wild match. */
        if (protocol == answer->protocol) {
            if (protocol != IPPROTO_IP)
                break;
        } else {
            /* Check for the two wild cases. */
            if (IPPROTO_IP == protocol) {
                protocol = answer->protocol;
                break;
            }
            if (IPPROTO_IP == answer->protocol)
                break;
        }
        err = -EPROTONOSUPPORT;
    }

    if (unlikely(err)) {
        if (try_loading_module < 2) {
            rcu_read_unlock();
            /*
             * Be more specific, e.g. net-pf-2-proto-132-type-1
             * (net-pf-PF_INET-proto-IPPROTO_SCTP-type-SOCK_STREAM)
             */
            if (++try_loading_module == 1)
                request_module("net-pf-%d-proto-%d-type-%d",
                           PF_INET, protocol, sock->type);
            /*
             * Fall back to generic, e.g. net-pf-2-proto-132
             * (net-pf-PF_INET-proto-IPPROTO_SCTP)
             */
            else
                request_module("net-pf-%d-proto-%d",
                           PF_INET, protocol);
            goto lookup_protocol;
        } else
            goto out_rcu_unlock;
    }

    err = -EPERM;
    if (sock->type == SOCK_RAW && !kern && !capable(CAP_NET_RAW))
        goto out_rcu_unlock;

    err = -EAFNOSUPPORT;
    if (!inet_netns_ok(net, protocol))
        goto out_rcu_unlock;

    sock->ops = answer->ops;
    answer_prot = answer->prot;
    answer_no_check = answer->no_check;
    answer_flags = answer->flags;
    rcu_read_unlock();

    WARN_ON(answer_prot->slab == NULL);

    err = -ENOBUFS;
    sk = sk_alloc(net, PF_INET, GFP_KERNEL, answer_prot);
    if (sk == NULL)
        goto out;

    err = 0;
    sk->sk_no_check = answer_no_check;
    if (INET_PROTOSW_REUSE & answer_flags)
        sk->sk_reuse = SK_CAN_REUSE;

    inet = inet_sk(sk);
    inet->is_icsk = (INET_PROTOSW_ICSK & answer_flags) != 0;

    inet->nodefrag = 0;

    if (SOCK_RAW == sock->type) {
        inet->inet_num = protocol;
        if (IPPROTO_RAW == protocol)
            inet->hdrincl = 1;
    }

    if (ipv4_config.no_pmtu_disc)
        inet->pmtudisc = IP_PMTUDISC_DONT;
    else
        inet->pmtudisc = IP_PMTUDISC_WANT;

    inet->inet_id = 0;

    sock_init_data(sock, sk);

    sk->sk_destruct    = inet_sock_destruct;
    sk->sk_protocol    = protocol;
    sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;

    inet->uc_ttl    = -1;
    inet->mc_loop   = 1;
    inet->mc_ttl    = 1;
    inet->mc_all    = 1;
    inet->mc_index  = 0;
    inet->mc_list   = NULL;
    inet->rcv_tos   = 0;

    sk_refcnt_debug_inc(sk);

    if (inet->inet_num) {
        /* It assumes that any protocol which allows
         * the user to assign a number at socket
         * creation time automatically
         * shares.
         */
        inet->inet_sport = htons(inet->inet_num);
        /* Add to protocol hash chains. */
        sk->sk_prot->hash(sk);
    }

    if (sk->sk_prot->init) {
        err = sk->sk_prot->init(sk);
        if (err)
            sk_common_release(sk);
    }
out:
    return err;
out_rcu_unlock:
    rcu_read_unlock();
    goto out;
}


/*
 *  The peer socket should always be NULL (or else). When we call this
 *  function we are destroying the object and from then on nobody
 *  should refer to it.
 */
int inet_release(struct socket *sock)
{
    struct sock *sk = sock->sk;

    if (sk) {
        long timeout;

        sock_rps_reset_flow(sk);

        /* Applications forget to leave groups before exiting */
        ip_mc_drop_socket(sk);

        /* If linger is set, we don't return until the close
         * is complete.  Otherwise we return immediately. The
         * actually closing is done the same either way.
         *
         * If the close is due to the process exiting, we never
         * linger..
         */
        timeout = 0;
        if (sock_flag(sk, SOCK_LINGER) &&
            !(current->flags & PF_EXITING))
            timeout = sk->sk_lingertime;
        sock->sk = NULL;
        sk->sk_prot->close(sk, timeout);
    }
    return 0;
}
EXPORT_SYMBOL(inet_release);

/* It is off by default, see below. */
int sysctl_ip_nonlocal_bind __read_mostly;
EXPORT_SYMBOL(sysctl_ip_nonlocal_bind);

int inet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
{
    struct sockaddr_in *addr = (struct sockaddr_in *)uaddr;
    struct sock *sk = sock->sk;
    struct inet_sock *inet = inet_sk(sk);
    unsigned short snum;
    int chk_addr_ret;
    int err;

    /* If the socket has its own bind function then use it. (RAW) */
    if (sk->sk_prot->bind) {
        err = sk->sk_prot->bind(sk, uaddr, addr_len);
        goto out;
    }
    err = -EINVAL;
    if (addr_len < sizeof(struct sockaddr_in))
        goto out;

    if (addr->sin_family != AF_INET) {
        /* Compatibility games : accept AF_UNSPEC (mapped to AF_INET)
         * only if s_addr is INADDR_ANY.
         */
        err = -EAFNOSUPPORT;
        if (addr->sin_family != AF_UNSPEC ||
            addr->sin_addr.s_addr != htonl(INADDR_ANY))
            goto out;
    }

    chk_addr_ret = inet_addr_type(sock_net(sk), addr->sin_addr.s_addr);

    /* Not specified by any standard per-se, however it breaks too
     * many applications when removed.  It is unfortunate since
     * allowing applications to make a non-local bind solves
     * several problems with systems using dynamic addressing.
     * (ie. your servers still start up even if your ISDN link
     *  is temporarily down)
     */
    err = -EADDRNOTAVAIL;
    if (!sysctl_ip_nonlocal_bind &&
        !(inet->freebind || inet->transparent) &&
        addr->sin_addr.s_addr != htonl(INADDR_ANY) &&
        chk_addr_ret != RTN_LOCAL &&
        chk_addr_ret != RTN_MULTICAST &&
        chk_addr_ret != RTN_BROADCAST)
        goto out;

    snum = ntohs(addr->sin_port);
    err = -EACCES;
    if (snum && snum < PROT_SOCK && !capable(CAP_NET_BIND_SERVICE))
        goto out;

    /*      We keep a pair of addresses. rcv_saddr is the one
     *      used by hash lookups, and saddr is used for transmit.
     *
     *      In the BSD API these are the same except where it
     *      would be illegal to use them (multicast/broadcast) in
     *      which case the sending device address is used.
     */
    lock_sock(sk);

    /* Check these errors (active socket, double bind). */
    err = -EINVAL;
    if (sk->sk_state != TCP_CLOSE || inet->inet_num)
        goto out_release_sock;

    inet->inet_rcv_saddr = inet->inet_saddr = addr->sin_addr.s_addr;
    if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST)
        inet->inet_saddr = 0;  /* Use device */

    /* Make sure we are allowed to bind here. */
    if (sk->sk_prot->get_port(sk, snum)) {
        inet->inet_saddr = inet->inet_rcv_saddr = 0;
        err = -EADDRINUSE;
        goto out_release_sock;
    }

    if (inet->inet_rcv_saddr)
        sk->sk_userlocks |= SOCK_BINDADDR_LOCK;
    if (snum)
        sk->sk_userlocks |= SOCK_BINDPORT_LOCK;
    inet->inet_sport = htons(inet->inet_num);
    inet->inet_daddr = 0;
    inet->inet_dport = 0;
    sk_dst_reset(sk);
    err = 0;
out_release_sock:
    release_sock(sk);
out:
    return err;
}
EXPORT_SYMBOL(inet_bind);

int inet_dgram_connect(struct socket *sock, struct sockaddr *uaddr,
               int addr_len, int flags)
{
    struct sock *sk = sock->sk;

    if (addr_len < sizeof(uaddr->sa_family))
        return -EINVAL;
    if (uaddr->sa_family == AF_UNSPEC)
        return sk->sk_prot->disconnect(sk, flags);

    if (!inet_sk(sk)->inet_num && inet_autobind(sk))
        return -EAGAIN;
    return sk->sk_prot->connect(sk, uaddr, addr_len);
}
EXPORT_SYMBOL(inet_dgram_connect);

static long inet_wait_for_connect(struct sock *sk, long timeo, int writebias)
{
    DEFINE_WAIT(wait);

    prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
    sk->sk_write_pending += writebias;

    /* Basic assumption: if someone sets sk->sk_err, he _must_
     * change state of the socket from TCP_SYN_*.
     * Connect() does not allow to get error notifications
     * without closing the socket.
     */
    while ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
        release_sock(sk);
        timeo = schedule_timeout(timeo);
        lock_sock(sk);
        if (signal_pending(current) || !timeo)
            break;
        prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
    }
    finish_wait(sk_sleep(sk), &wait);
    sk->sk_write_pending -= writebias;
    return timeo;
}

/*
 *  Connect to a remote host. There is regrettably still a little
 *  TCP 'magic' in here.
 */
int __inet_stream_connect(struct socket *sock, struct sockaddr *uaddr,
              int addr_len, int flags)
{
    struct sock *sk = sock->sk;
    int err;
    long timeo;

    if (addr_len < sizeof(uaddr->sa_family))
        return -EINVAL;

    if (uaddr->sa_family == AF_UNSPEC) {
        err = sk->sk_prot->disconnect(sk, flags);
        sock->state = err ? SS_DISCONNECTING : SS_UNCONNECTED;
        goto out;
    }

    switch (sock->state) {
    default:
        err = -EINVAL;
        goto out;
    case SS_CONNECTED:
        err = -EISCONN;
        goto out;
    case SS_CONNECTING:
        err = -EALREADY;
        /* Fall out of switch with err, set for this state */
        break;
    case SS_UNCONNECTED:
        err = -EISCONN;
        if (sk->sk_state != TCP_CLOSE)
            goto out;

        err = sk->sk_prot->connect(sk, uaddr, addr_len);
        if (err < 0)
            goto out;

        sock->state = SS_CONNECTING;

        /* Just entered SS_CONNECTING state; the only
         * difference is that return value in non-blocking
         * case is EINPROGRESS, rather than EALREADY.
         */
        err = -EINPROGRESS;
        break;
    }

    timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);

    if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
        int writebias = (sk->sk_protocol == IPPROTO_TCP) &&
                tcp_sk(sk)->fastopen_req &&
                tcp_sk(sk)->fastopen_req->data ? 1 : 0;

        /* Error code is set above */
        if (!timeo || !inet_wait_for_connect(sk, timeo, writebias))
            goto out;

        err = sock_intr_errno(timeo);
        if (signal_pending(current))
            goto out;
    }

    /* Connection was closed by RST, timeout, ICMP error
     * or another process disconnected us.
     */
    if (sk->sk_state == TCP_CLOSE)
        goto sock_error;

    /* sk->sk_err may be not zero now, if RECVERR was ordered by user
     * and error was received after socket entered established state.
     * Hence, it is handled normally after connect() return successfully.
     */

    sock->state = SS_CONNECTED;
    err = 0;
out:
    return err;

sock_error:
    err = sock_error(sk) ? : -ECONNABORTED;
    sock->state = SS_UNCONNECTED;
    if (sk->sk_prot->disconnect(sk, flags))
        sock->state = SS_DISCONNECTING;
    goto out;
}
EXPORT_SYMBOL(__inet_stream_connect);

int inet_stream_connect(struct socket *sock, struct sockaddr *uaddr,
            int addr_len, int flags)
{
    int err;

    lock_sock(sock->sk);
    err = __inet_stream_connect(sock, uaddr, addr_len, flags);
    release_sock(sock->sk);
    return err;
}
EXPORT_SYMBOL(inet_stream_connect);

/*
 *  Accept a pending connection. The TCP layer now gives BSD semantics.
 */

int inet_accept(struct socket *sock, struct socket *newsock, int flags)
{
    struct sock *sk1 = sock->sk;
    int err = -EINVAL;
    struct sock *sk2 = sk1->sk_prot->accept(sk1, flags, &err);

    if (!sk2)
        goto do_err;

    lock_sock(sk2);

    sock_rps_record_flow(sk2);
    WARN_ON(!((1 << sk2->sk_state) &
          (TCPF_ESTABLISHED | TCPF_SYN_RECV |
          TCPF_CLOSE_WAIT | TCPF_CLOSE)));

    sock_graft(sk2, newsock);

    newsock->state = SS_CONNECTED;
    err = 0;
    release_sock(sk2);
do_err:
    return err;
}
EXPORT_SYMBOL(inet_accept);


/*
 *  This does both peername and sockname.
 */
int inet_getname(struct socket *sock, struct sockaddr *uaddr,
            int *uaddr_len, int peer)
{
    struct sock *sk     = sock->sk;
    struct inet_sock *inet  = inet_sk(sk);
    DECLARE_SOCKADDR(struct sockaddr_in *, sin, uaddr);

    sin->sin_family = AF_INET;
    if (peer) {
        if (!inet->inet_dport ||
            (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_SYN_SENT)) &&
             peer == 1))
            return -ENOTCONN;
        sin->sin_port = inet->inet_dport;
        sin->sin_addr.s_addr = inet->inet_daddr;
    } else {
        __be32 addr = inet->inet_rcv_saddr;
        if (!addr)
            addr = inet->inet_saddr;
        sin->sin_port = inet->inet_sport;
        sin->sin_addr.s_addr = addr;
    }
    memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
    *uaddr_len = sizeof(*sin);
    return 0;
}
EXPORT_SYMBOL(inet_getname);

int inet_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
         size_t size)
{
    struct sock *sk = sock->sk;

    sock_rps_record_flow(sk);

    /* We may need to bind the socket. */
    if (!inet_sk(sk)->inet_num && !sk->sk_prot->no_autobind &&
        inet_autobind(sk))
        return -EAGAIN;

    return sk->sk_prot->sendmsg(iocb, sk, msg, size);
}
EXPORT_SYMBOL(inet_sendmsg);

ssize_t inet_sendpage(struct socket *sock, struct page *page, int offset,
              size_t size, int flags)
{
    struct sock *sk = sock->sk;

    sock_rps_record_flow(sk);

    /* We may need to bind the socket. */
    if (!inet_sk(sk)->inet_num && !sk->sk_prot->no_autobind &&
        inet_autobind(sk))
        return -EAGAIN;

    if (sk->sk_prot->sendpage)
        return sk->sk_prot->sendpage(sk, page, offset, size, flags);
    return sock_no_sendpage(sock, page, offset, size, flags);
}
EXPORT_SYMBOL(inet_sendpage);

int inet_recvmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
         size_t size, int flags)
{
    struct sock *sk = sock->sk;
    int addr_len = 0;
    int err;

    sock_rps_record_flow(sk);

    err = sk->sk_prot->recvmsg(iocb, sk, msg, size, flags & MSG_DONTWAIT,
                   flags & ~MSG_DONTWAIT, &addr_len);
    if (err >= 0)
        msg->msg_namelen = addr_len;
    return err;
}
EXPORT_SYMBOL(inet_recvmsg);

int inet_shutdown(struct socket *sock, int how)
{
    struct sock *sk = sock->sk;
    int err = 0;

    /* This should really check to make sure
     * the socket is a TCP socket. (WHY AC...)
     */
    how++; /* maps 0->1 has the advantage of making bit 1 rcvs and
               1->2 bit 2 snds.
               2->3 */
    if ((how & ~SHUTDOWN_MASK) || !how) /* MAXINT->0 */
        return -EINVAL;

    lock_sock(sk);
    if (sock->state == SS_CONNECTING) {
        if ((1 << sk->sk_state) &
            (TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_CLOSE))
            sock->state = SS_DISCONNECTING;
        else
            sock->state = SS_CONNECTED;
    }

    switch (sk->sk_state) {
    case TCP_CLOSE:
        err = -ENOTCONN;
        /* Hack to wake up other listeners, who can poll for
           POLLHUP, even on eg. unconnected UDP sockets -- RR */
    default:
        sk->sk_shutdown |= how;
        if (sk->sk_prot->shutdown)
            sk->sk_prot->shutdown(sk, how);
        break;

    /* Remaining two branches are temporary solution for missing
     * close() in multithreaded environment. It is _not_ a good idea,
     * but we have no choice until close() is repaired at VFS level.
     */
    case TCP_LISTEN:
        if (!(how & RCV_SHUTDOWN))
            break;
        /* Fall through */
    case TCP_SYN_SENT:
        err = sk->sk_prot->disconnect(sk, O_NONBLOCK);
        sock->state = err ? SS_DISCONNECTING : SS_UNCONNECTED;
        break;
    }

    /* Wake up anyone sleeping in poll. */
    sk->sk_state_change(sk);
    release_sock(sk);
    return err;
}
EXPORT_SYMBOL(inet_shutdown);

/*
 *  ioctl() calls you can issue on an INET socket. Most of these are
 *  device configuration and stuff and very rarely used. Some ioctls
 *  pass on to the socket itself.
 *
 *  NOTE: I like the idea of a module for the config stuff. ie ifconfig
 *  loads the devconfigure module does its configuring and unloads it.
 *  There's a good 20K of config code hanging around the kernel.
 */

int inet_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
    struct sock *sk = sock->sk;
    int err = 0;
    struct net *net = sock_net(sk);

    switch (cmd) {
    case SIOCGSTAMP:
        err = sock_get_timestamp(sk, (struct timeval __user *)arg);
        break;
    case SIOCGSTAMPNS:
        err = sock_get_timestampns(sk, (struct timespec __user *)arg);
        break;
    case SIOCADDRT:
    case SIOCDELRT:
    case SIOCRTMSG:
        err = ip_rt_ioctl(net, cmd, (void __user *)arg);
        break;
    case SIOCDARP:
    case SIOCGARP:
    case SIOCSARP:
        err = arp_ioctl(net, cmd, (void __user *)arg);
        break;
    case SIOCGIFADDR:
    case SIOCSIFADDR:
    case SIOCGIFBRDADDR:
    case SIOCSIFBRDADDR:
    case SIOCGIFNETMASK:
    case SIOCSIFNETMASK:
    case SIOCGIFDSTADDR:
    case SIOCSIFDSTADDR:
    case SIOCSIFPFLAGS:
    case SIOCGIFPFLAGS:
    case SIOCSIFFLAGS:
        err = devinet_ioctl(net, cmd, (void __user *)arg);
        break;
    default:
        if (sk->sk_prot->ioctl)
            err = sk->sk_prot->ioctl(sk, cmd, arg);
        else
            err = -ENOIOCTLCMD;
        break;
    }
    return err;
}
EXPORT_SYMBOL(inet_ioctl);

#ifdef CONFIG_COMPAT
static int inet_compat_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
    struct sock *sk = sock->sk;
    int err = -ENOIOCTLCMD;

    if (sk->sk_prot->compat_ioctl)
        err = sk->sk_prot->compat_ioctl(sk, cmd, arg);

    return err;
}
#endif

const struct proto_ops inet_stream_ops = {
    .family        = PF_INET,
    .owner         = THIS_MODULE,
    .release       = inet_release,
    .bind          = inet_bind,
    .connect       = inet_stream_connect,
    .socketpair    = sock_no_socketpair,
    .accept        = inet_accept,
    .getname       = inet_getname,
    .poll          = tcp_poll,
    .ioctl         = inet_ioctl,
    .listen        = inet_listen,
    .shutdown      = inet_shutdown,
    .setsockopt    = sock_common_setsockopt,
    .getsockopt    = sock_common_getsockopt,
    .sendmsg       = inet_sendmsg,
    .recvmsg       = inet_recvmsg,
    .mmap          = sock_no_mmap,
    .sendpage      = inet_sendpage,
    .splice_read       = tcp_splice_read,
#ifdef CONFIG_COMPAT
    .compat_setsockopt = compat_sock_common_setsockopt,
    .compat_getsockopt = compat_sock_common_getsockopt,
    .compat_ioctl      = inet_compat_ioctl,
#endif
};
EXPORT_SYMBOL(inet_stream_ops);

const struct proto_ops inet_dgram_ops = {
    .family        = PF_INET,
    .owner         = THIS_MODULE,
    .release       = inet_release,
    .bind          = inet_bind,
    .connect       = inet_dgram_connect,
    .socketpair    = sock_no_socketpair,
    .accept        = sock_no_accept,
    .getname       = inet_getname,
    .poll          = udp_poll,
    .ioctl         = inet_ioctl,
    .listen        = sock_no_listen,
    .shutdown      = inet_shutdown,
    .setsockopt    = sock_common_setsockopt,
    .getsockopt    = sock_common_getsockopt,
    .sendmsg       = inet_sendmsg,
    .recvmsg       = inet_recvmsg,
    .mmap          = sock_no_mmap,
    .sendpage      = inet_sendpage,
#ifdef CONFIG_COMPAT
    .compat_setsockopt = compat_sock_common_setsockopt,
    .compat_getsockopt = compat_sock_common_getsockopt,
    .compat_ioctl      = inet_compat_ioctl,
#endif
};
EXPORT_SYMBOL(inet_dgram_ops);

/*
 * For SOCK_RAW sockets; should be the same as inet_dgram_ops but without
 * udp_poll
 */
static const struct proto_ops inet_sockraw_ops = {
    .family        = PF_INET,
    .owner         = THIS_MODULE,
    .release       = inet_release,
    .bind          = inet_bind,
    .connect       = inet_dgram_connect,
    .socketpair    = sock_no_socketpair,
    .accept        = sock_no_accept,
    .getname       = inet_getname,
    .poll          = datagram_poll,
    .ioctl         = inet_ioctl,
    .listen        = sock_no_listen,
    .shutdown      = inet_shutdown,
    .setsockopt    = sock_common_setsockopt,
    .getsockopt    = sock_common_getsockopt,
    .sendmsg       = inet_sendmsg,
    .recvmsg       = inet_recvmsg,
    .mmap          = sock_no_mmap,
    .sendpage      = inet_sendpage,
#ifdef CONFIG_COMPAT
    .compat_setsockopt = compat_sock_common_setsockopt,
    .compat_getsockopt = compat_sock_common_getsockopt,
    .compat_ioctl      = inet_compat_ioctl,
#endif
};

static const struct net_proto_family inet_family_ops = {
    .family = PF_INET,
    .create = inet_create,
    .owner  = THIS_MODULE,
};

/* Upon startup we insert all the elements in inetsw_array[] into
 * the linked list inetsw.
 */
static struct inet_protosw inetsw_array[] =
{
    {
        .type =       SOCK_STREAM,
        .protocol =   IPPROTO_TCP,
        .prot =       &tcp_prot,
        .ops =        &inet_stream_ops,
        .no_check =   0,
        .flags =      INET_PROTOSW_PERMANENT |
                  INET_PROTOSW_ICSK,
    },

    {
        .type =       SOCK_DGRAM,
        .protocol =   IPPROTO_UDP,
        .prot =       &udp_prot,
        .ops =        &inet_dgram_ops,
        .no_check =   UDP_CSUM_DEFAULT,
        .flags =      INET_PROTOSW_PERMANENT,
       },

       {
        .type =       SOCK_DGRAM,
        .protocol =   IPPROTO_ICMP,
        .prot =       &ping_prot,
        .ops =        &inet_dgram_ops,
        .no_check =   UDP_CSUM_DEFAULT,
        .flags =      INET_PROTOSW_REUSE,
       },

       {
           .type =       SOCK_RAW,
           .protocol =   IPPROTO_IP,    /* wild card */
           .prot =       &raw_prot,
           .ops =        &inet_sockraw_ops,
           .no_check =   UDP_CSUM_DEFAULT,
           .flags =      INET_PROTOSW_REUSE,
       }
};

#define INETSW_ARRAY_LEN ARRAY_SIZE(inetsw_array)

void inet_register_protosw(struct inet_protosw *p)
{
    struct list_head *lh;
    struct inet_protosw *answer;
    int protocol = p->protocol;
    struct list_head *last_perm;

    spin_lock_bh(&inetsw_lock);

    if (p->type >= SOCK_MAX)
        goto out_illegal;

    /* If we are trying to override a permanent protocol, bail. */
    answer = NULL;
    last_perm = &inetsw[p->type];
    list_for_each(lh, &inetsw[p->type]) {
        answer = list_entry(lh, struct inet_protosw, list);

        /* Check only the non-wild match. */
        if (INET_PROTOSW_PERMANENT & answer->flags) {
            if (protocol == answer->protocol)
                break;
            last_perm = lh;
        }

        answer = NULL;
    }
    if (answer)
        goto out_permanent;

    /* Add the new entry after the last permanent entry if any, so that
     * the new entry does not override a permanent entry when matched with
     * a wild-card protocol. But it is allowed to override any existing
     * non-permanent entry.  This means that when we remove this entry, the
     * system automatically returns to the old behavior.
     */
    list_add_rcu(&p->list, last_perm);
out:
    spin_unlock_bh(&inetsw_lock);

    return;

out_permanent:
    pr_err("Attempt to override permanent protocol %d\n", protocol);
    goto out;

out_illegal:
    pr_err("Ignoring attempt to register invalid socket type %d\n",
           p->type);
    goto out;
}
EXPORT_SYMBOL(inet_register_protosw);

void inet_unregister_protosw(struct inet_protosw *p)
{
    if (INET_PROTOSW_PERMANENT & p->flags) {
        pr_err("Attempt to unregister permanent protocol %d\n",
               p->protocol);
    } else {
        spin_lock_bh(&inetsw_lock);
        list_del_rcu(&p->list);
        spin_unlock_bh(&inetsw_lock);

        synchronize_net();
    }
}
EXPORT_SYMBOL(inet_unregister_protosw);

/*
 *      Shall we try to damage output packets if routing dev changes?
 */

int sysctl_ip_dynaddr __read_mostly;

static int inet_sk_reselect_saddr(struct sock *sk)
{
    struct inet_sock *inet = inet_sk(sk);
    __be32 old_saddr = inet->inet_saddr;
    __be32 daddr = inet->inet_daddr;
    struct flowi4 *fl4;
    struct rtable *rt;
    __be32 new_saddr;
    struct ip_options_rcu *inet_opt;

    inet_opt = rcu_dereference_protected(inet->inet_opt,
                         sock_owned_by_user(sk));
    if (inet_opt && inet_opt->opt.srr)
        daddr = inet_opt->opt.faddr;

    /* Query new route. */
    fl4 = &inet->cork.fl.u.ip4;
    rt = ip_route_connect(fl4, daddr, 0, RT_CONN_FLAGS(sk),
                  sk->sk_bound_dev_if, sk->sk_protocol,
                  inet->inet_sport, inet->inet_dport, sk, false);
    if (IS_ERR(rt))
        return PTR_ERR(rt);

    sk_setup_caps(sk, &rt->dst);

    new_saddr = fl4->saddr;

    if (new_saddr == old_saddr)
        return 0;

    if (sysctl_ip_dynaddr > 1) {
        pr_info("%s(): shifting inet->saddr from %pI4 to %pI4\n",
            __func__, &old_saddr, &new_saddr);
    }

    inet->inet_saddr = inet->inet_rcv_saddr = new_saddr;

    /*
     * XXX The only one ugly spot where we need to
     * XXX really change the sockets identity after
     * XXX it has entered the hashes. -DaveM
     *
     * Besides that, it does not check for connection
     * uniqueness. Wait for troubles.
     */
    __sk_prot_rehash(sk);
    return 0;
}

int inet_sk_rebuild_header(struct sock *sk)
{
    struct inet_sock *inet = inet_sk(sk);
    struct rtable *rt = (struct rtable *)__sk_dst_check(sk, 0);
    __be32 daddr;
    struct ip_options_rcu *inet_opt;
    struct flowi4 *fl4;
    int err;

    /* Route is OK, nothing to do. */
    if (rt)
        return 0;

    /* Reroute. */
    rcu_read_lock();
    inet_opt = rcu_dereference(inet->inet_opt);
    daddr = inet->inet_daddr;
    if (inet_opt && inet_opt->opt.srr)
        daddr = inet_opt->opt.faddr;
    rcu_read_unlock();
    fl4 = &inet->cork.fl.u.ip4;
    rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr, inet->inet_saddr,
                   inet->inet_dport, inet->inet_sport,
                   sk->sk_protocol, RT_CONN_FLAGS(sk),
                   sk->sk_bound_dev_if);
    if (!IS_ERR(rt)) {
        err = 0;
        sk_setup_caps(sk, &rt->dst);
    } else {
        err = PTR_ERR(rt);

        /* Routing failed... */
        sk->sk_route_caps = 0;
        /*
         * Other protocols have to map its equivalent state to TCP_SYN_SENT.
         * DCCP maps its DCCP_REQUESTING state to TCP_SYN_SENT. -acme
         */
        if (!sysctl_ip_dynaddr ||
            sk->sk_state != TCP_SYN_SENT ||
            (sk->sk_userlocks & SOCK_BINDADDR_LOCK) ||
            (err = inet_sk_reselect_saddr(sk)) != 0)
            sk->sk_err_soft = -err;
    }

    return err;
}
EXPORT_SYMBOL(inet_sk_rebuild_header);

static int inet_gso_send_check(struct sk_buff *skb)
{
    const struct net_protocol *ops;
    const struct iphdr *iph;
    int proto;
    int ihl;
    int err = -EINVAL;

    if (unlikely(!pskb_may_pull(skb, sizeof(*iph))))
        goto out;

    iph = ip_hdr(skb);
    ihl = iph->ihl * 4;
    if (ihl < sizeof(*iph))
        goto out;

    if (unlikely(!pskb_may_pull(skb, ihl)))
        goto out;

    __skb_pull(skb, ihl);
    skb_reset_transport_header(skb);
    iph = ip_hdr(skb);
    proto = iph->protocol;
    err = -EPROTONOSUPPORT;

    rcu_read_lock();
    ops = rcu_dereference(inet_protos[proto]);
    if (likely(ops && ops->gso_send_check))
        err = ops->gso_send_check(skb);
    rcu_read_unlock();

out:
    return err;
}

static struct sk_buff *inet_gso_segment(struct sk_buff *skb,
    netdev_features_t features)
{
    struct sk_buff *segs = ERR_PTR(-EINVAL);
    const struct net_protocol *ops;
    struct iphdr *iph;
    int proto;
    int ihl;
    int id;
    unsigned int offset = 0;

    if (!(features & NETIF_F_V4_CSUM))
        features &= ~NETIF_F_SG;

    if (unlikely(skb_shinfo(skb)->gso_type &
             ~(SKB_GSO_TCPV4 |
               SKB_GSO_UDP |
               SKB_GSO_DODGY |
               SKB_GSO_TCP_ECN |
               0)))
        goto out;

    if (unlikely(!pskb_may_pull(skb, sizeof(*iph))))
        goto out;

    iph = ip_hdr(skb);
    ihl = iph->ihl * 4;
    if (ihl < sizeof(*iph))
        goto out;

    if (unlikely(!pskb_may_pull(skb, ihl)))
        goto out;

    __skb_pull(skb, ihl);
    skb_reset_transport_header(skb);
    iph = ip_hdr(skb);
    id = ntohs(iph->id);
    proto = iph->protocol;
    segs = ERR_PTR(-EPROTONOSUPPORT);

    rcu_read_lock();
    ops = rcu_dereference(inet_protos[proto]);
    if (likely(ops && ops->gso_segment))
        segs = ops->gso_segment(skb, features);
    rcu_read_unlock();

    if (!segs || IS_ERR(segs))
        goto out;

    skb = segs;
    do {
        iph = ip_hdr(skb);
        if (proto == IPPROTO_UDP) {
            iph->id = htons(id);
            iph->frag_off = htons(offset >> 3);
            if (skb->next != NULL)
                iph->frag_off |= htons(IP_MF);
            offset += (skb->len - skb->mac_len - iph->ihl * 4);
        } else
            iph->id = htons(id++);
        iph->tot_len = htons(skb->len - skb->mac_len);
        iph->check = 0;
        iph->check = ip_fast_csum(skb_network_header(skb), iph->ihl);
    } while ((skb = skb->next));

out:
    return segs;
}

static struct sk_buff **inet_gro_receive(struct sk_buff **head,
                     struct sk_buff *skb)
{
    const struct net_protocol *ops;
    struct sk_buff **pp = NULL;
    struct sk_buff *p;
    const struct iphdr *iph;
    unsigned int hlen;
    unsigned int off;
    unsigned int id;
    int flush = 1;
    int proto;

    off = skb_gro_offset(skb);
    hlen = off + sizeof(*iph);
    iph = skb_gro_header_fast(skb, off);
    if (skb_gro_header_hard(skb, hlen)) {
        iph = skb_gro_header_slow(skb, hlen, off);
        if (unlikely(!iph))
            goto out;
    }

    proto = iph->protocol;

    rcu_read_lock();
    ops = rcu_dereference(inet_protos[proto]);
    if (!ops || !ops->gro_receive)
        goto out_unlock;

    if (*(u8 *)iph != 0x45)
        goto out_unlock;

    if (unlikely(ip_fast_csum((u8 *)iph, 5)))
        goto out_unlock;

    id = ntohl(*(__be32 *)&iph->id);
    flush = (u16)((ntohl(*(__be32 *)iph) ^ skb_gro_len(skb)) | (id ^ IP_DF));
    id >>= 16;

    for (p = *head; p; p = p->next) {
        struct iphdr *iph2;

        if (!NAPI_GRO_CB(p)->same_flow)
            continue;

        iph2 = ip_hdr(p);

        if ((iph->protocol ^ iph2->protocol) |
            ((__force u32)iph->saddr ^ (__force u32)iph2->saddr) |
            ((__force u32)iph->daddr ^ (__force u32)iph2->daddr)) {
            NAPI_GRO_CB(p)->same_flow = 0;
            continue;
        }

        /* All fields must match except length and checksum. */
        NAPI_GRO_CB(p)->flush |=
            (iph->ttl ^ iph2->ttl) |
            (iph->tos ^ iph2->tos) |
            ((u16)(ntohs(iph2->id) + NAPI_GRO_CB(p)->count) ^ id);

        NAPI_GRO_CB(p)->flush |= flush;
    }

    NAPI_GRO_CB(skb)->flush |= flush;
    skb_gro_pull(skb, sizeof(*iph));
    skb_set_transport_header(skb, skb_gro_offset(skb));

    pp = ops->gro_receive(head, skb);

out_unlock:
    rcu_read_unlock();

out:
    NAPI_GRO_CB(skb)->flush |= flush;

    return pp;
}

static int inet_gro_complete(struct sk_buff *skb)
{
    __be16 newlen = htons(skb->len - skb_network_offset(skb));
    struct iphdr *iph = ip_hdr(skb);
    const struct net_protocol *ops;
    int proto = iph->protocol;
    int err = -ENOSYS;

    csum_replace2(&iph->check, iph->tot_len, newlen);
    iph->tot_len = newlen;

    rcu_read_lock();
    ops = rcu_dereference(inet_protos[proto]);
    if (WARN_ON(!ops || !ops->gro_complete))
        goto out_unlock;

    err = ops->gro_complete(skb);

out_unlock:
    rcu_read_unlock();

    return err;
}

int inet_ctl_sock_create(struct sock **sk, unsigned short family,
             unsigned short type, unsigned char protocol,
             struct net *net)
{
    struct socket *sock;
    int rc = sock_create_kern(family, type, protocol, &sock);

    if (rc == 0) {
        *sk = sock->sk;
        (*sk)->sk_allocation = GFP_ATOMIC;
        /*
         * Unhash it so that IP input processing does not even see it,
         * we do not wish this socket to see incoming packets.
         */
        (*sk)->sk_prot->unhash(*sk);

        sk_change_net(*sk, net);
    }
    return rc;
}
EXPORT_SYMBOL_GPL(inet_ctl_sock_create);

unsigned long snmp_fold_field(void __percpu *mib[], int offt)
{
    unsigned long res = 0;
    int i, j;

    for_each_possible_cpu(i) {
        for (j = 0; j < SNMP_ARRAY_SZ; j++)
            res += *(((unsigned long *) per_cpu_ptr(mib[j], i)) + offt);
    }
    return res;
}
EXPORT_SYMBOL_GPL(snmp_fold_field);

#if BITS_PER_LONG==32

u64 snmp_fold_field64(void __percpu *mib[], int offt, size_t syncp_offset)
{
    u64 res = 0;
    int cpu;

    for_each_possible_cpu(cpu) {
        void *bhptr;
        struct u64_stats_sync *syncp;
        u64 v;
        unsigned int start;

        bhptr = per_cpu_ptr(mib[0], cpu);
        syncp = (struct u64_stats_sync *)(bhptr + syncp_offset);
        do {
            start = u64_stats_fetch_begin_bh(syncp);
            v = *(((u64 *) bhptr) + offt);
        } while (u64_stats_fetch_retry_bh(syncp, start));

        res += v;
    }
    return res;
}
EXPORT_SYMBOL_GPL(snmp_fold_field64);
#endif

int snmp_mib_init(void __percpu *ptr[2], size_t mibsize, size_t align)
{
    BUG_ON(ptr == NULL);
    ptr[0] = __alloc_percpu(mibsize, align);
    if (!ptr[0])
        return -ENOMEM;
#if SNMP_ARRAY_SZ == 2
    ptr[1] = __alloc_percpu(mibsize, align);
    if (!ptr[1]) {
        free_percpu(ptr[0]);
        ptr[0] = NULL;
        return -ENOMEM;
    }
#endif
    return 0;
}
EXPORT_SYMBOL_GPL(snmp_mib_init);

void snmp_mib_free(void __percpu *ptr[SNMP_ARRAY_SZ])
{
    int i;

    BUG_ON(ptr == NULL);
    for (i = 0; i < SNMP_ARRAY_SZ; i++) {
        free_percpu(ptr[i]);
        ptr[i] = NULL;
    }
}
EXPORT_SYMBOL_GPL(snmp_mib_free);

#ifdef CONFIG_IP_MULTICAST
static const struct net_protocol igmp_protocol = {
    .handler =  igmp_rcv,
    .netns_ok = 1,
};
#endif

static const struct net_protocol tcp_protocol = {
    .early_demux    =   tcp_v4_early_demux,
    .handler    =   tcp_v4_rcv,
    .err_handler    =   tcp_v4_err,
    .gso_send_check =   tcp_v4_gso_send_check,
    .gso_segment    =   tcp_tso_segment,
    .gro_receive    =   tcp4_gro_receive,
    .gro_complete   =   tcp4_gro_complete,
    .no_policy  =   1,
    .netns_ok   =   1,
};

static const struct net_protocol udp_protocol = {
    .handler =  udp_rcv,
    .err_handler =  udp_err,
    .gso_send_check = udp4_ufo_send_check,
    .gso_segment = udp4_ufo_fragment,
    .no_policy =    1,
    .netns_ok = 1,
};

static const struct net_protocol icmp_protocol = {
    .handler =  icmp_rcv,
    .err_handler =  ping_err,
    .no_policy =    1,
    .netns_ok = 1,
};

static __net_init int ipv4_mib_init_net(struct net *net)
{
    if (snmp_mib_init((void __percpu **)net->mib.tcp_statistics,
              sizeof(struct tcp_mib),
              __alignof__(struct tcp_mib)) < 0)
        goto err_tcp_mib;
    if (snmp_mib_init((void __percpu **)net->mib.ip_statistics,
              sizeof(struct ipstats_mib),
              __alignof__(struct ipstats_mib)) < 0)
        goto err_ip_mib;
    if (snmp_mib_init((void __percpu **)net->mib.net_statistics,
              sizeof(struct linux_mib),
              __alignof__(struct linux_mib)) < 0)
        goto err_net_mib;
    if (snmp_mib_init((void __percpu **)net->mib.udp_statistics,
              sizeof(struct udp_mib),
              __alignof__(struct udp_mib)) < 0)
        goto err_udp_mib;
    if (snmp_mib_init((void __percpu **)net->mib.udplite_statistics,
              sizeof(struct udp_mib),
              __alignof__(struct udp_mib)) < 0)
        goto err_udplite_mib;
    if (snmp_mib_init((void __percpu **)net->mib.icmp_statistics,
              sizeof(struct icmp_mib),
              __alignof__(struct icmp_mib)) < 0)
        goto err_icmp_mib;
    net->mib.icmpmsg_statistics = kzalloc(sizeof(struct icmpmsg_mib),
                          GFP_KERNEL);
    if (!net->mib.icmpmsg_statistics)
        goto err_icmpmsg_mib;

    tcp_mib_init(net);
    return 0;

err_icmpmsg_mib:
    snmp_mib_free((void __percpu **)net->mib.icmp_statistics);
err_icmp_mib:
    snmp_mib_free((void __percpu **)net->mib.udplite_statistics);
err_udplite_mib:
    snmp_mib_free((void __percpu **)net->mib.udp_statistics);
err_udp_mib:
    snmp_mib_free((void __percpu **)net->mib.net_statistics);
err_net_mib:
    snmp_mib_free((void __percpu **)net->mib.ip_statistics);
err_ip_mib:
    snmp_mib_free((void __percpu **)net->mib.tcp_statistics);
err_tcp_mib:
    return -ENOMEM;
}

static __net_exit void ipv4_mib_exit_net(struct net *net)
{
    kfree(net->mib.icmpmsg_statistics);
    snmp_mib_free((void __percpu **)net->mib.icmp_statistics);
    snmp_mib_free((void __percpu **)net->mib.udplite_statistics);
    snmp_mib_free((void __percpu **)net->mib.udp_statistics);
    snmp_mib_free((void __percpu **)net->mib.net_statistics);
    snmp_mib_free((void __percpu **)net->mib.ip_statistics);
    snmp_mib_free((void __percpu **)net->mib.tcp_statistics);
}

static __net_initdata struct pernet_operations ipv4_mib_ops = {
    .init = ipv4_mib_init_net,
    .exit = ipv4_mib_exit_net,
};

static int __init init_ipv4_mibs(void)
{
    return register_pernet_subsys(&ipv4_mib_ops);
}

static int ipv4_proc_init(void);

/*
 *  IP protocol layer initialiser
 */

static struct packet_type ip_packet_type __read_mostly = {
    .type = cpu_to_be16(ETH_P_IP),
    .func = ip_rcv,
    .gso_send_check = inet_gso_send_check,
    .gso_segment = inet_gso_segment,
    .gro_receive = inet_gro_receive,
    .gro_complete = inet_gro_complete,
};

static int __init inet_init(void)
{
    struct sk_buff *dummy_skb;
    struct inet_protosw *q;
    struct list_head *r;
    int rc = -EINVAL;

    BUILD_BUG_ON(sizeof(struct inet_skb_parm) > sizeof(dummy_skb->cb));

    sysctl_local_reserved_ports = kzalloc(65536 / 8, GFP_KERNEL);
    if (!sysctl_local_reserved_ports)
        goto out;

    rc = proto_register(&tcp_prot, 1);
    if (rc)
        goto out_free_reserved_ports;

    rc = proto_register(&udp_prot, 1);
    if (rc)
        goto out_unregister_tcp_proto;

    rc = proto_register(&raw_prot, 1);
    if (rc)
        goto out_unregister_udp_proto;

    rc = proto_register(&ping_prot, 1);
    if (rc)
        goto out_unregister_raw_proto;

    /*
     *  Tell SOCKET that we are alive...
     */

    (void)sock_register(&inet_family_ops);

#ifdef CONFIG_SYSCTL
    ip_static_sysctl_init();
#endif

    tcp_prot.sysctl_mem = init_net.ipv4.sysctl_tcp_mem;

    /*
     *  Add all the base protocols.
     */

    if (inet_add_protocol(&icmp_protocol, IPPROTO_ICMP) < 0)
        pr_crit("%s: Cannot add ICMP protocol\n", __func__);
    if (inet_add_protocol(&udp_protocol, IPPROTO_UDP) < 0)
        pr_crit("%s: Cannot add UDP protocol\n", __func__);
    if (inet_add_protocol(&tcp_protocol, IPPROTO_TCP) < 0)
        pr_crit("%s: Cannot add TCP protocol\n", __func__);
#ifdef CONFIG_IP_MULTICAST
    if (inet_add_protocol(&igmp_protocol, IPPROTO_IGMP) < 0)
        pr_crit("%s: Cannot add IGMP protocol\n", __func__);
#endif

    /* Register the socket-side information for inet_create. */
    for (r = &inetsw[0]; r < &inetsw[SOCK_MAX]; ++r)
        INIT_LIST_HEAD(r);

    for (q = inetsw_array; q < &inetsw_array[INETSW_ARRAY_LEN]; ++q)
        inet_register_protosw(q);

    /*
     *  Set the ARP module up
     */

    arp_init();

    /*
     *  Set the IP module up
     */

    ip_init();

    tcp_v4_init();

    /* Setup TCP slab cache for open requests. */
    tcp_init();

    /* Setup UDP memory threshold */
    udp_init();

    /* Add UDP-Lite (RFC 3828) */
    udplite4_register();

    ping_init();

    /*
     *  Set the ICMP layer up
     */

    if (icmp_init() < 0)
        panic("Failed to create the ICMP control socket.\n");

    /*
     *  Initialise the multicast router
     */
#if defined(CONFIG_IP_MROUTE)
    if (ip_mr_init())
        pr_crit("%s: Cannot init ipv4 mroute\n", __func__);
#endif
    /*
     *  Initialise per-cpu ipv4 mibs
     */

    if (init_ipv4_mibs())
        pr_crit("%s: Cannot init ipv4 mibs\n", __func__);

    ipv4_proc_init();

    ipfrag_init();

    dev_add_pack(&ip_packet_type);

    rc = 0;
out:
    return rc;
out_unregister_raw_proto:
    proto_unregister(&raw_prot);
out_unregister_udp_proto:
    proto_unregister(&udp_prot);
out_unregister_tcp_proto:
    proto_unregister(&tcp_prot);
out_free_reserved_ports:
    kfree(sysctl_local_reserved_ports);
    goto out;
}

fs_initcall(inet_init);

/* ------------------------------------------------------------------------ */

#ifdef CONFIG_PROC_FS
static int __init ipv4_proc_init(void)
{
    int rc = 0;

    if (raw_proc_init())
        goto out_raw;
    if (tcp4_proc_init())
        goto out_tcp;
    if (udp4_proc_init())
        goto out_udp;
    if (ping_proc_init())
        goto out_ping;
    if (ip_misc_proc_init())
        goto out_misc;
out:
    return rc;
out_misc:
    ping_proc_exit();
out_ping:
    udp4_proc_exit();
out_udp:
    tcp4_proc_exit();
out_tcp:
    raw_proc_exit();
out_raw:
    rc = -ENOMEM;
    goto out;
}

#else /* CONFIG_PROC_FS */
static int __init ipv4_proc_init(void)
{
    return 0;
}
#endif /* CONFIG_PROC_FS */

MODULE_ALIAS_NETPROTO(PF_INET);