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32 results

af_inet.c

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  • af_inet.c 45.44 KiB
    /*
     * 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, <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.
     */
    
    #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/inet_common.h>
    #include <net/ip_tunnels.h>
    #include <net/xfrm.h>
    #include <net/net_namespace.h>
    #include <net/secure_seq.h>
    #ifdef CONFIG_IP_MROUTE
    #include <linux/mroute.h>
    #endif
    #include <net/l3mdev.h>
    
    
    /* 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);
    
    	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.max_qlen) {
    			if ((sysctl_tcp_fastopen & TFO_SERVER_WO_SOCKOPT1) != 0)
    				fastopen_queue_tune(sk, backlog);
    			else if ((sysctl_tcp_fastopen &
    				  TFO_SERVER_WO_SOCKOPT2) != 0)
    				fastopen_queue_tune(sk,
    				    ((uint)sysctl_tcp_fastopen) >> 16);
    
    			tcp_fastopen_init_key_once(true);
    		}
    		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);
    
    /*
     *	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;
    	int try_loading_module = 0;
    	int err;
    
    	if (protocol < 0 || protocol >= IPPROTO_MAX)
    		return -EINVAL;
    
    	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 &&
    	    !ns_capable(net->user_ns, CAP_NET_RAW))
    		goto out_rcu_unlock;
    
    	sock->ops = answer->ops;
    	answer_prot = answer->prot;
    	answer_flags = answer->flags;
    	rcu_read_unlock();
    
    	WARN_ON(!answer_prot->slab);
    
    	err = -ENOBUFS;
    	sk = sk_alloc(net, PF_INET, GFP_KERNEL, answer_prot, kern);
    	if (!sk)
    		goto out;
    
    	err = 0;
    	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 (net->ipv4.sysctl_ip_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. */
    		err = sk->sk_prot->hash(sk);
    		if (err) {
    			sk_common_release(sk);
    			goto out;
    		}
    	}
    
    	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;
    }
    EXPORT_SYMBOL(inet_release);
    
    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);
    	struct net *net = sock_net(sk);
    	unsigned short snum;
    	int chk_addr_ret;
    	u32 tb_id = RT_TABLE_LOCAL;
    	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;
    	}
    
    	tb_id = l3mdev_fib_table_by_index(net, sk->sk_bound_dev_if) ? : tb_id;
    	chk_addr_ret = inet_addr_type_table(net, addr->sin_addr.s_addr, tb_id);
    
    	/* 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 (!net->ipv4.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 &&
    	    !ns_capable(net->user_ns, 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 ((snum || !inet->bind_address_no_port) &&
    	    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 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(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 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(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,
    		.flags =      INET_PROTOSW_PERMANENT |
    			      INET_PROTOSW_ICSK,
    	},
    
    	{
    		.type =       SOCK_DGRAM,
    		.protocol =   IPPROTO_UDP,
    		.prot =       &udp_prot,
    		.ops =        &inet_dgram_ops,
    		.flags =      INET_PROTOSW_PERMANENT,
           },
    
           {
    		.type =       SOCK_DGRAM,
    		.protocol =   IPPROTO_ICMP,
    		.prot =       &ping_prot,
    		.ops =        &inet_dgram_ops,
    		.flags =      INET_PROTOSW_REUSE,
           },
    
           {
    	       .type =       SOCK_RAW,
    	       .protocol =   IPPROTO_IP,	/* wild card */
    	       .prot =       &raw_prot,
    	       .ops =        &inet_sockraw_ops,
    	       .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. */
    	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) == 0)
    			break;
    		if (protocol == answer->protocol)
    			goto out_permanent;
    		last_perm = lh;
    	}
    
    	/* 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);
    
    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);
    	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 (sock_net(sk)->ipv4.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.
    	 */
    	return __sk_prot_rehash(sk);
    }
    
    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 (!sock_net(sk)->ipv4.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 struct sk_buff *inet_gso_segment(struct sk_buff *skb,
    					netdev_features_t features)
    {
    	struct sk_buff *segs = ERR_PTR(-EINVAL);
    	const struct net_offload *ops;
    	unsigned int offset = 0;
    	bool udpfrag, encap;
    	struct iphdr *iph;
    	int proto;
    	int nhoff;
    	int ihl;
    	int id;
    
    	if (unlikely(skb_shinfo(skb)->gso_type &
    		     ~(SKB_GSO_TCPV4 |
    		       SKB_GSO_UDP |
    		       SKB_GSO_DODGY |
    		       SKB_GSO_TCP_ECN |
    		       SKB_GSO_GRE |
    		       SKB_GSO_GRE_CSUM |
    		       SKB_GSO_IPIP |
    		       SKB_GSO_SIT |
    		       SKB_GSO_TCPV6 |
    		       SKB_GSO_UDP_TUNNEL |
    		       SKB_GSO_UDP_TUNNEL_CSUM |
    		       SKB_GSO_TUNNEL_REMCSUM |
    		       0)))
    		goto out;
    
    	skb_reset_network_header(skb);
    	nhoff = skb_network_header(skb) - skb_mac_header(skb);
    	if (unlikely(!pskb_may_pull(skb, sizeof(*iph))))
    		goto out;
    
    	iph = ip_hdr(skb);
    	ihl = iph->ihl * 4;
    	if (ihl < sizeof(*iph))
    		goto out;
    
    	id = ntohs(iph->id);
    	proto = iph->protocol;
    
    	/* Warning: after this point, iph might be no longer valid */
    	if (unlikely(!pskb_may_pull(skb, ihl)))
    		goto out;
    	__skb_pull(skb, ihl);
    
    	encap = SKB_GSO_CB(skb)->encap_level > 0;
    	if (encap)
    		features &= skb->dev->hw_enc_features;
    	SKB_GSO_CB(skb)->encap_level += ihl;
    
    	skb_reset_transport_header(skb);
    
    	segs = ERR_PTR(-EPROTONOSUPPORT);
    
    	if (skb->encapsulation &&
    	    skb_shinfo(skb)->gso_type & (SKB_GSO_SIT|SKB_GSO_IPIP))
    		udpfrag = proto == IPPROTO_UDP && encap;
    	else
    		udpfrag = proto == IPPROTO_UDP && !skb->encapsulation;
    
    	ops = rcu_dereference(inet_offloads[proto]);
    	if (likely(ops && ops->callbacks.gso_segment))
    		segs = ops->callbacks.gso_segment(skb, features);
    
    	if (IS_ERR_OR_NULL(segs))
    		goto out;
    
    	skb = segs;
    	do {
    		iph = (struct iphdr *)(skb_mac_header(skb) + nhoff);
    		if (udpfrag) {
    			iph->id = htons(id);
    			iph->frag_off = htons(offset >> 3);
    			if (skb->next)
    				iph->frag_off |= htons(IP_MF);
    			offset += skb->len - nhoff - ihl;
    		} else {
    			iph->id = htons(id++);
    		}
    		iph->tot_len = htons(skb->len - nhoff);
    		ip_send_check(iph);
    		if (encap)
    			skb_reset_inner_headers(skb);
    		skb->network_header = (u8 *)iph - skb->head;
    	} 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_offload *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_offloads[proto]);
    	if (!ops || !ops->callbacks.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 = (struct iphdr *)(p->data + off);
    		/* The above works because, with the exception of the top
    		 * (inner most) layer, we only aggregate pkts with the same
    		 * hdr length so all the hdrs we'll need to verify will start
    		 * at the same offset.
    		 */
    		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) |
    			((iph->frag_off ^ iph2->frag_off) & htons(IP_DF));
    
    		/* Save the IP ID check to be included later when we get to
    		 * the transport layer so only the inner most IP ID is checked.
    		 * This is because some GSO/TSO implementations do not
    		 * correctly increment the IP ID for the outer hdrs.
    		 */
    		NAPI_GRO_CB(p)->flush_id =
    			    ((u16)(ntohs(iph2->id) + NAPI_GRO_CB(p)->count) ^ id);
    		NAPI_GRO_CB(p)->flush |= flush;
    	}
    
    	NAPI_GRO_CB(skb)->flush |= flush;
    	skb_set_network_header(skb, off);
    	/* The above will be needed by the transport layer if there is one
    	 * immediately following this IP hdr.
    	 */
    
    	/* Note : No need to call skb_gro_postpull_rcsum() here,
    	 * as we already checked checksum over ipv4 header was 0
    	 */
    	skb_gro_pull(skb, sizeof(*iph));
    	skb_set_transport_header(skb, skb_gro_offset(skb));
    
    	pp = ops->callbacks.gro_receive(head, skb);
    
    out_unlock:
    	rcu_read_unlock();
    
    out:
    	NAPI_GRO_CB(skb)->flush |= flush;
    
    	return pp;
    }
    
    #define SECONDS_PER_DAY	86400
    
    /* inet_current_timestamp - Return IP network timestamp
     *
     * Return milliseconds since midnight in network byte order.
     */
    __be32 inet_current_timestamp(void)
    {
    	u32 secs;
    	u32 msecs;
    	struct timespec64 ts;
    
    	ktime_get_real_ts64(&ts);
    
    	/* Get secs since midnight. */
    	(void)div_u64_rem(ts.tv_sec, SECONDS_PER_DAY, &secs);
    	/* Convert to msecs. */
    	msecs = secs * MSEC_PER_SEC;
    	/* Convert nsec to msec. */
    	msecs += (u32)ts.tv_nsec / NSEC_PER_MSEC;
    
    	/* Convert to network byte order. */
    	return htons(msecs);
    }
    EXPORT_SYMBOL(inet_current_timestamp);
    
    int inet_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
    {
    	if (sk->sk_family == AF_INET)
    		return ip_recv_error(sk, msg, len, addr_len);
    #if IS_ENABLED(CONFIG_IPV6)
    	if (sk->sk_family == AF_INET6)
    		return pingv6_ops.ipv6_recv_error(sk, msg, len, addr_len);
    #endif
    	return -EINVAL;
    }
    
    static int inet_gro_complete(struct sk_buff *skb, int nhoff)
    {
    	__be16 newlen = htons(skb->len - nhoff);
    	struct iphdr *iph = (struct iphdr *)(skb->data + nhoff);
    	const struct net_offload *ops;
    	int proto = iph->protocol;
    	int err = -ENOSYS;
    
    	if (skb->encapsulation)
    		skb_set_inner_network_header(skb, nhoff);
    
    	csum_replace2(&iph->check, iph->tot_len, newlen);
    	iph->tot_len = newlen;
    
    	rcu_read_lock();
    	ops = rcu_dereference(inet_offloads[proto]);
    	if (WARN_ON(!ops || !ops->callbacks.gro_complete))
    		goto out_unlock;
    
    	/* Only need to add sizeof(*iph) to get to the next hdr below
    	 * because any hdr with option will have been flushed in
    	 * inet_gro_receive().
    	 */
    	err = ops->callbacks.gro_complete(skb, nhoff + sizeof(*iph));
    
    out_unlock:
    	rcu_read_unlock();
    
    	return err;
    }
    
    static int ipip_gro_complete(struct sk_buff *skb, int nhoff)
    {
    	skb->encapsulation = 1;
    	skb_shinfo(skb)->gso_type |= SKB_GSO_IPIP;
    	return inet_gro_complete(skb, nhoff);
    }
    
    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(net, 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);
    	}
    	return rc;
    }
    EXPORT_SYMBOL_GPL(inet_ctl_sock_create);
    
    u64 snmp_get_cpu_field(void __percpu *mib, int cpu, int offt)
    {
    	return  *(((unsigned long *)per_cpu_ptr(mib, cpu)) + offt);
    }
    EXPORT_SYMBOL_GPL(snmp_get_cpu_field);
    
    unsigned long snmp_fold_field(void __percpu *mib, int offt)
    {
    	unsigned long res = 0;
    	int i;
    
    	for_each_possible_cpu(i)
    		res += snmp_get_cpu_field(mib, i, offt);
    	return res;
    }
    EXPORT_SYMBOL_GPL(snmp_fold_field);
    
    #if BITS_PER_LONG==32
    
    u64 snmp_get_cpu_field64(void __percpu *mib, int cpu, int offt,
    			 size_t syncp_offset)
    {
    	void *bhptr;
    	struct u64_stats_sync *syncp;
    	u64 v;
    	unsigned int start;
    
    	bhptr = per_cpu_ptr(mib, cpu);
    	syncp = (struct u64_stats_sync *)(bhptr + syncp_offset);
    	do {
    		start = u64_stats_fetch_begin_irq(syncp);
    		v = *(((u64 *)bhptr) + offt);
    	} while (u64_stats_fetch_retry_irq(syncp, start));
    
    	return v;
    }
    EXPORT_SYMBOL_GPL(snmp_get_cpu_field64);
    
    u64 snmp_fold_field64(void __percpu *mib, int offt, size_t syncp_offset)
    {
    	u64 res = 0;
    	int cpu;
    
    	for_each_possible_cpu(cpu) {
    		res += snmp_get_cpu_field64(mib, cpu, offt, syncp_offset);
    	}
    	return res;
    }
    EXPORT_SYMBOL_GPL(snmp_fold_field64);
    #endif
    
    #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,
    	.no_policy	=	1,
    	.netns_ok	=	1,
    	.icmp_strict_tag_validation = 1,
    };
    
    static const struct net_protocol udp_protocol = {
    	.early_demux =	udp_v4_early_demux,
    	.handler =	udp_rcv,
    	.err_handler =	udp_err,
    	.no_policy =	1,
    	.netns_ok =	1,
    };
    
    static const struct net_protocol icmp_protocol = {
    	.handler =	icmp_rcv,
    	.err_handler =	icmp_err,
    	.no_policy =	1,
    	.netns_ok =	1,
    };
    
    static __net_init int ipv4_mib_init_net(struct net *net)
    {
    	int i;
    
    	net->mib.tcp_statistics = alloc_percpu(struct tcp_mib);
    	if (!net->mib.tcp_statistics)
    		goto err_tcp_mib;
    	net->mib.ip_statistics = alloc_percpu(struct ipstats_mib);
    	if (!net->mib.ip_statistics)
    		goto err_ip_mib;
    
    	for_each_possible_cpu(i) {
    		struct ipstats_mib *af_inet_stats;
    		af_inet_stats = per_cpu_ptr(net->mib.ip_statistics, i);
    		u64_stats_init(&af_inet_stats->syncp);
    	}
    
    	net->mib.net_statistics = alloc_percpu(struct linux_mib);
    	if (!net->mib.net_statistics)
    		goto err_net_mib;
    	net->mib.udp_statistics = alloc_percpu(struct udp_mib);
    	if (!net->mib.udp_statistics)
    		goto err_udp_mib;
    	net->mib.udplite_statistics = alloc_percpu(struct udp_mib);
    	if (!net->mib.udplite_statistics)
    		goto err_udplite_mib;
    	net->mib.icmp_statistics = alloc_percpu(struct icmp_mib);
    	if (!net->mib.icmp_statistics)
    		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:
    	free_percpu(net->mib.icmp_statistics);
    err_icmp_mib:
    	free_percpu(net->mib.udplite_statistics);
    err_udplite_mib:
    	free_percpu(net->mib.udp_statistics);
    err_udp_mib:
    	free_percpu(net->mib.net_statistics);
    err_net_mib:
    	free_percpu(net->mib.ip_statistics);
    err_ip_mib:
    	free_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);
    	free_percpu(net->mib.icmp_statistics);
    	free_percpu(net->mib.udplite_statistics);
    	free_percpu(net->mib.udp_statistics);
    	free_percpu(net->mib.net_statistics);
    	free_percpu(net->mib.ip_statistics);
    	free_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 __net_init int inet_init_net(struct net *net)
    {
    	/*
    	 * Set defaults for local port range
    	 */
    	seqlock_init(&net->ipv4.ip_local_ports.lock);
    	net->ipv4.ip_local_ports.range[0] =  32768;
    	net->ipv4.ip_local_ports.range[1] =  60999;
    
    	seqlock_init(&net->ipv4.ping_group_range.lock);
    	/*
    	 * Sane defaults - nobody may create ping sockets.
    	 * Boot scripts should set this to distro-specific group.
    	 */
    	net->ipv4.ping_group_range.range[0] = make_kgid(&init_user_ns, 1);
    	net->ipv4.ping_group_range.range[1] = make_kgid(&init_user_ns, 0);
    	return 0;
    }
    
    static __net_exit void inet_exit_net(struct net *net)
    {
    }
    
    static __net_initdata struct pernet_operations af_inet_ops = {
    	.init = inet_init_net,
    	.exit = inet_exit_net,
    };
    
    static int __init init_inet_pernet_ops(void)
    {
    	return register_pernet_subsys(&af_inet_ops);
    }
    
    static int ipv4_proc_init(void);
    
    /*
     *	IP protocol layer initialiser
     */
    
    static struct packet_offload ip_packet_offload __read_mostly = {
    	.type = cpu_to_be16(ETH_P_IP),
    	.callbacks = {
    		.gso_segment = inet_gso_segment,
    		.gro_receive = inet_gro_receive,
    		.gro_complete = inet_gro_complete,
    	},
    };
    
    static const struct net_offload ipip_offload = {
    	.callbacks = {
    		.gso_segment	= inet_gso_segment,
    		.gro_receive	= inet_gro_receive,
    		.gro_complete	= ipip_gro_complete,
    	},
    };
    
    static int __init ipv4_offload_init(void)
    {
    	/*
    	 * Add offloads
    	 */
    	if (udpv4_offload_init() < 0)
    		pr_crit("%s: Cannot add UDP protocol offload\n", __func__);
    	if (tcpv4_offload_init() < 0)
    		pr_crit("%s: Cannot add TCP protocol offload\n", __func__);
    
    	dev_add_offload(&ip_packet_offload);
    	inet_add_offload(&ipip_offload, IPPROTO_IPIP);
    	return 0;
    }
    
    fs_initcall(ipv4_offload_init);
    
    static struct packet_type ip_packet_type __read_mostly = {
    	.type = cpu_to_be16(ETH_P_IP),
    	.func = ip_rcv,
    };
    
    static int __init inet_init(void)
    {
    	struct inet_protosw *q;
    	struct list_head *r;
    	int rc = -EINVAL;
    
    	sock_skb_cb_check_size(sizeof(struct inet_skb_parm));
    
    	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;
    
    	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
    
    	/*
    	 *	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
    
    	if (init_inet_pernet_ops())
    		pr_crit("%s: Cannot init ipv4 inet pernet ops\n", __func__);
    	/*
    	 *	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);
    
    	ip_tunnel_core_init();
    
    	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);
    	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);