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af_inet.c

/*
 * 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.
 *
 * Version: $Id: af_inet.c,v 1.137 2002/02/01 22:01:03 davem Exp $
 *
 * Authors: Ross Biro
 *          Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *          Florian La Roche, <flla@stud.uni-sb.de>
 *          Alan Cox, <A.Cox@swansea.ac.uk>
 *
 * 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.
 */

#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 <asm/uaccess.h>
#include <asm/system.h>

#include <linux/inet.h>
#include <linux/igmp.h>
#include <linux/inetdevice.h>
#include <linux/netdevice.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 <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>
#ifdef CONFIG_IP_MROUTE
#include <linux/mroute.h>
#endif

DEFINE_SNMP_STAT(struct linux_mib, net_statistics) __read_mostly;

extern void ip_mc_drop_socket(struct sock *sk);

/* 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);

/* 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);

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

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

      kfree(inet->opt);
      dst_release(sk->sk_dst_cache);
      sk_refcnt_debug_dec(sk);
}

/*
 *    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->num) {
            if (sk->sk_prot->get_port(sk, 0)) {
                  release_sock(sk);
                  return -EAGAIN;
            }
            inet->sport = htons(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) {
            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;
}

u32 inet_ehash_secret __read_mostly;
EXPORT_SYMBOL(inet_ehash_secret);

/*
 * inet_ehash_secret must be set exactly once
 * Instead of using a dedicated spinlock, we (ab)use inetsw_lock
 */
void build_ehash_secret(void)
{
      u32 rnd;
      do {
            get_random_bytes(&rnd, sizeof(rnd));
      } while (rnd == 0);
      spin_lock_bh(&inetsw_lock);
      if (!inet_ehash_secret)
            inet_ehash_secret = rnd;
      spin_unlock_bh(&inetsw_lock);
}
EXPORT_SYMBOL(build_ehash_secret);

/*
 *    Create an inet socket.
 */

static int inet_create(struct net *net, struct socket *sock, int protocol)
{
      struct sock *sk;
      struct list_head *p;
      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 (net != &init_net)
            return -EAFNOSUPPORT;

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

      sock->state = SS_UNCONNECTED;

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

            /* 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;
            answer = NULL;
      }

      if (unlikely(answer == NULL)) {
            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 (answer->capability > 0 && !capable(answer->capability))
            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();

      BUG_TRAP(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 = 1;

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

      if (SOCK_RAW == sock->type) {
            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->id = 0;

      sock_init_data(sock, sk);

      sk->sk_destruct      = inet_sock_destruct;
      sk->sk_family        = PF_INET;
      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_index    = 0;
      inet->mc_list     = NULL;

      sk_refcnt_debug_inc(sk);

      if (inet->num) {
            /* It assumes that any protocol which allows
             * the user to assign a number at socket
             * creation time automatically
             * shares.
             */
            inet->sport = htons(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;

            /* 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;
}

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

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;

      chk_addr_ret = inet_addr_type(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 &&
          addr->sin_addr.s_addr != 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->num)
            goto out_release_sock;

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

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

      if (inet->rcv_saddr)
            sk->sk_userlocks |= SOCK_BINDADDR_LOCK;
      if (snum)
            sk->sk_userlocks |= SOCK_BINDPORT_LOCK;
      inet->sport = htons(inet->num);
      inet->daddr = 0;
      inet->dport = 0;
      sk_dst_reset(sk);
      err = 0;
out_release_sock:
      release_sock(sk);
out:
      return err;
}

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

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

      if (!inet_sk(sk)->num && inet_autobind(sk))
            return -EAGAIN;
      return sk->sk_prot->connect(sk, (struct sockaddr *)uaddr, addr_len);
}

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

      prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);

      /* 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->sk_sleep, &wait, TASK_INTERRUPTIBLE);
      }
      finish_wait(sk->sk_sleep, &wait);
      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;

      lock_sock(sk);

      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)) {
            /* Error code is set above */
            if (!timeo || !inet_wait_for_connect(sk, timeo))
                  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:
      release_sock(sk);
      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;
}

/*
 *    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);

      BUG_TRAP((1 << sk2->sk_state) &
             (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_CLOSE));

      sock_graft(sk2, newsock);

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


/*
 *    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);
      struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;

      sin->sin_family = AF_INET;
      if (peer) {
            if (!inet->dport ||
                (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_SYN_SENT)) &&
                 peer == 1))
                  return -ENOTCONN;
            sin->sin_port = inet->dport;
            sin->sin_addr.s_addr = inet->daddr;
      } else {
            __be32 addr = inet->rcv_saddr;
            if (!addr)
                  addr = inet->saddr;
            sin->sin_port = inet->sport;
            sin->sin_addr.s_addr = addr;
      }
      memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
      *uaddr_len = sizeof(*sin);
      return 0;
}

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

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

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


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

      /* We may need to bind the socket. */
      if (!inet_sk(sk)->num && 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);
}


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;
}

/*
 *    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;

      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(cmd, (void __user *)arg);
                  break;
            case SIOCDARP:
            case SIOCGARP:
            case SIOCSARP:
                  err = arp_ioctl(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(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;
}

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       = tcp_sendmsg,
      .recvmsg       = sock_common_recvmsg,
      .mmap          = sock_no_mmap,
      .sendpage      = tcp_sendpage,
#ifdef CONFIG_COMPAT
      .compat_setsockopt = compat_sock_common_setsockopt,
      .compat_getsockopt = compat_sock_common_getsockopt,
#endif
};

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       = sock_common_recvmsg,
      .mmap          = sock_no_mmap,
      .sendpage      = inet_sendpage,
#ifdef CONFIG_COMPAT
      .compat_setsockopt = compat_sock_common_setsockopt,
      .compat_getsockopt = compat_sock_common_getsockopt,
#endif
};

/*
 * 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       = sock_common_recvmsg,
      .mmap          = sock_no_mmap,
      .sendpage      = inet_sendpage,
#ifdef CONFIG_COMPAT
      .compat_setsockopt = compat_sock_common_setsockopt,
      .compat_getsockopt = compat_sock_common_getsockopt,
#endif
};

static 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,
            .capability = -1,
            .no_check =   0,
            .flags =      INET_PROTOSW_PERMANENT |
                        INET_PROTOSW_ICSK,
      },

      {
            .type =       SOCK_DGRAM,
            .protocol =   IPPROTO_UDP,
            .prot =       &udp_prot,
            .ops =        &inet_dgram_ops,
            .capability = -1,
            .no_check =   UDP_CSUM_DEFAULT,
            .flags =      INET_PROTOSW_PERMANENT,
       },


       {
             .type =       SOCK_RAW,
             .protocol =   IPPROTO_IP,    /* wild card */
             .prot =       &raw_prot,
             .ops =        &inet_sockraw_ops,
             .capability = CAP_NET_RAW,
             .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);

      synchronize_net();

      return;

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

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

void inet_unregister_protosw(struct inet_protosw *p)
{
      if (INET_PROTOSW_PERMANENT & p->flags) {
            printk(KERN_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();
      }
}

/*
 *      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);
      int err;
      struct rtable *rt;
      __be32 old_saddr = inet->saddr;
      __be32 new_saddr;
      __be32 daddr = inet->daddr;

      if (inet->opt && inet->opt->srr)
            daddr = inet->opt->faddr;

      /* Query new route. */
      err = ip_route_connect(&rt, daddr, 0,
                         RT_CONN_FLAGS(sk),
                         sk->sk_bound_dev_if,
                         sk->sk_protocol,
                         inet->sport, inet->dport, sk, 0);
      if (err)
            return err;

      sk_setup_caps(sk, &rt->u.dst);

      new_saddr = rt->rt_src;

      if (new_saddr == old_saddr)
            return 0;

      if (sysctl_ip_dynaddr > 1) {
            printk(KERN_INFO "%s(): shifting inet->"
                         "saddr from %d.%d.%d.%d to %d.%d.%d.%d\n",
                   __FUNCTION__,
                   NIPQUAD(old_saddr),
                   NIPQUAD(new_saddr));
      }

      inet->saddr = 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;
      int err;

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

      /* Reroute. */
      daddr = inet->daddr;
      if (inet->opt && inet->opt->srr)
            daddr = inet->opt->faddr;
{
      struct flowi fl = {
            .oif = sk->sk_bound_dev_if,
            .nl_u = {
                  .ip4_u = {
                        .daddr      = daddr,
                        .saddr      = inet->saddr,
                        .tos  = RT_CONN_FLAGS(sk),
                  },
            },
            .proto = sk->sk_protocol,
            .uli_u = {
                  .ports = {
                        .sport = inet->sport,
                        .dport = inet->dport,
                  },
            },
      };

      security_sk_classify_flow(sk, &fl);
      err = ip_route_output_flow(&rt, &fl, sk, 0);
}
      if (!err)
            sk_setup_caps(sk, &rt->u.dst);
      else {
            /* 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)
{
      struct iphdr *iph;
      struct net_protocol *ops;
      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 & (MAX_INET_PROTOS - 1);
      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, int features)
{
      struct sk_buff *segs = ERR_PTR(-EINVAL);
      struct iphdr *iph;
      struct net_protocol *ops;
      int proto;
      int ihl;
      int id;

      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 & (MAX_INET_PROTOS - 1);
      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 || unlikely(IS_ERR(segs)))
            goto out;

      skb = segs;
      do {
            iph = ip_hdr(skb);
            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;
}

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

      for_each_possible_cpu(i) {
            res += *(((unsigned long *) per_cpu_ptr(mib[0], i)) + offt);
            res += *(((unsigned long *) per_cpu_ptr(mib[1], i)) + offt);
      }
      return res;
}
EXPORT_SYMBOL_GPL(snmp_fold_field);

int snmp_mib_init(void *ptr[2], size_t mibsize, size_t mibalign)
{
      BUG_ON(ptr == NULL);
      ptr[0] = __alloc_percpu(mibsize);
      if (!ptr[0])
            goto err0;
      ptr[1] = __alloc_percpu(mibsize);
      if (!ptr[1])
            goto err1;
      return 0;
err1:
      free_percpu(ptr[0]);
      ptr[0] = NULL;
err0:
      return -ENOMEM;
}
EXPORT_SYMBOL_GPL(snmp_mib_init);

void snmp_mib_free(void *ptr[2])
{
      BUG_ON(ptr == NULL);
      free_percpu(ptr[0]);
      free_percpu(ptr[1]);
      ptr[0] = ptr[1] = NULL;
}
EXPORT_SYMBOL_GPL(snmp_mib_free);

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

static struct net_protocol tcp_protocol = {
      .handler =  tcp_v4_rcv,
      .err_handler =    tcp_v4_err,
      .gso_send_check = tcp_v4_gso_send_check,
      .gso_segment =    tcp_tso_segment,
      .no_policy =      1,
};

static struct net_protocol udp_protocol = {
      .handler =  udp_rcv,
      .err_handler =    udp_err,
      .no_policy =      1,
};

static struct net_protocol icmp_protocol = {
      .handler =  icmp_rcv,
};

static int __init init_ipv4_mibs(void)
{
      if (snmp_mib_init((void **)net_statistics,
                    sizeof(struct linux_mib),
                    __alignof__(struct linux_mib)) < 0)
            goto err_net_mib;
      if (snmp_mib_init((void **)ip_statistics,
                    sizeof(struct ipstats_mib),
                    __alignof__(struct ipstats_mib)) < 0)
            goto err_ip_mib;
      if (snmp_mib_init((void **)icmp_statistics,
                    sizeof(struct icmp_mib),
                    __alignof__(struct icmp_mib)) < 0)
            goto err_icmp_mib;
      if (snmp_mib_init((void **)icmpmsg_statistics,
                    sizeof(struct icmpmsg_mib),
                    __alignof__(struct icmpmsg_mib)) < 0)
            goto err_icmpmsg_mib;
      if (snmp_mib_init((void **)tcp_statistics,
                    sizeof(struct tcp_mib),
                    __alignof__(struct tcp_mib)) < 0)
            goto err_tcp_mib;
      if (snmp_mib_init((void **)udp_statistics,
                    sizeof(struct udp_mib),
                    __alignof__(struct udp_mib)) < 0)
            goto err_udp_mib;
      if (snmp_mib_init((void **)udplite_statistics,
                    sizeof(struct udp_mib),
                    __alignof__(struct udp_mib)) < 0)
            goto err_udplite_mib;

      tcp_mib_init();

      return 0;

err_udplite_mib:
      snmp_mib_free((void **)udp_statistics);
err_udp_mib:
      snmp_mib_free((void **)tcp_statistics);
err_tcp_mib:
      snmp_mib_free((void **)icmpmsg_statistics);
err_icmpmsg_mib:
      snmp_mib_free((void **)icmp_statistics);
err_icmp_mib:
      snmp_mib_free((void **)ip_statistics);
err_ip_mib:
      snmp_mib_free((void **)net_statistics);
err_net_mib:
      return -ENOMEM;
}

static int ipv4_proc_init(void);

/*
 *    IP protocol layer initialiser
 */

static struct packet_type ip_packet_type = {
      .type = __constant_htons(ETH_P_IP),
      .func = ip_rcv,
      .gso_send_check = inet_gso_send_check,
      .gso_segment = inet_gso_segment,
};

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));

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

      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;

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

      (void)sock_register(&inet_family_ops);

      /*
       *    Add all the base protocols.
       */

      if (inet_add_protocol(&icmp_protocol, IPPROTO_ICMP) < 0)
            printk(KERN_CRIT "inet_init: Cannot add ICMP protocol\n");
      if (inet_add_protocol(&udp_protocol, IPPROTO_UDP) < 0)
            printk(KERN_CRIT "inet_init: Cannot add UDP protocol\n");
      if (inet_add_protocol(&tcp_protocol, IPPROTO_TCP) < 0)
            printk(KERN_CRIT "inet_init: Cannot add TCP protocol\n");
#ifdef CONFIG_IP_MULTICAST
      if (inet_add_protocol(&igmp_protocol, IPPROTO_IGMP) < 0)
            printk(KERN_CRIT "inet_init: Cannot add IGMP protocol\n");
#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(&inet_family_ops);

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

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

      /*
       *    Set the ICMP layer up
       */

      icmp_init(&inet_family_ops);

      /*
       *    Initialise the multicast router
       */
#if defined(CONFIG_IP_MROUTE)
      ip_mr_init();
#endif
      /*
       *    Initialise per-cpu ipv4 mibs
       */

      if (init_ipv4_mibs())
            printk(KERN_CRIT "inet_init: Cannot init ipv4 mibs\n"); ;

      ipv4_proc_init();

      ipfrag_init();

      dev_add_pack(&ip_packet_type);

      rc = 0;
out:
      return rc;
out_unregister_udp_proto:
      proto_unregister(&udp_prot);
out_unregister_tcp_proto:
      proto_unregister(&tcp_prot);
      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 (fib_proc_init())
            goto out_fib;
      if (ip_misc_proc_init())
            goto out_misc;
out:
      return rc;
out_misc:
      fib_proc_exit();
out_fib:
      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);

EXPORT_SYMBOL(inet_accept);
EXPORT_SYMBOL(inet_bind);
EXPORT_SYMBOL(inet_dgram_connect);
EXPORT_SYMBOL(inet_dgram_ops);
EXPORT_SYMBOL(inet_getname);
EXPORT_SYMBOL(inet_ioctl);
EXPORT_SYMBOL(inet_listen);
EXPORT_SYMBOL(inet_register_protosw);
EXPORT_SYMBOL(inet_release);
EXPORT_SYMBOL(inet_sendmsg);
EXPORT_SYMBOL(inet_shutdown);
EXPORT_SYMBOL(inet_sock_destruct);
EXPORT_SYMBOL(inet_stream_connect);
EXPORT_SYMBOL(inet_stream_ops);
EXPORT_SYMBOL(inet_unregister_protosw);
EXPORT_SYMBOL(net_statistics);
EXPORT_SYMBOL(sysctl_ip_nonlocal_bind);

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