tcp_ipv4.c 46.7 KB
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/*
 * INET		An implementation of the TCP/IP protocol suite for the LINUX
 *		operating system.  INET is implemented using the  BSD Socket
 *		interface as the means of communication with the user level.
 *
 *		Implementation of the Transmission Control Protocol(TCP).
 *
 * Version:	$Id: tcp_ipv4.c,v 1.240 2002/02/01 22:01:04 davem Exp $
 *
 *		IPv4 specific functions
 *
 *
 *		code split from:
 *		linux/ipv4/tcp.c
 *		linux/ipv4/tcp_input.c
 *		linux/ipv4/tcp_output.c
 *
 *		See tcp.c for author information
 *
 *	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.
 */

/*
 * Changes:
 *		David S. Miller	:	New socket lookup architecture.
 *					This code is dedicated to John Dyson.
 *		David S. Miller :	Change semantics of established hash,
 *					half is devoted to TIME_WAIT sockets
 *					and the rest go in the other half.
 *		Andi Kleen :		Add support for syncookies and fixed
 *					some bugs: ip options weren't passed to
 *					the TCP layer, missed a check for an
 *					ACK bit.
 *		Andi Kleen :		Implemented fast path mtu discovery.
 *	     				Fixed many serious bugs in the
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 *					request_sock handling and moved
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 *					most of it into the af independent code.
 *					Added tail drop and some other bugfixes.
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 *					Added new listen semantics.
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 *		Mike McLagan	:	Routing by source
 *	Juan Jose Ciarlante:		ip_dynaddr bits
 *		Andi Kleen:		various fixes.
 *	Vitaly E. Lavrov	:	Transparent proxy revived after year
 *					coma.
 *	Andi Kleen		:	Fix new listen.
 *	Andi Kleen		:	Fix accept error reporting.
 *	YOSHIFUJI Hideaki @USAGI and:	Support IPV6_V6ONLY socket option, which
 *	Alexey Kuznetsov		allow both IPv4 and IPv6 sockets to bind
 *					a single port at the same time.
 */


#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/cache.h>
#include <linux/jhash.h>
#include <linux/init.h>
#include <linux/times.h>

#include <net/icmp.h>
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#include <net/inet_hashtables.h>
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#include <net/tcp.h>
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#include <net/transp_v6.h>
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#include <net/ipv6.h>
#include <net/inet_common.h>
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#include <net/timewait_sock.h>
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#include <net/xfrm.h>
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#include <net/netdma.h>
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#include <linux/inet.h>
#include <linux/ipv6.h>
#include <linux/stddef.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>

int sysctl_tcp_tw_reuse;
int sysctl_tcp_low_latency;

/* Check TCP sequence numbers in ICMP packets. */
#define ICMP_MIN_LENGTH 8

/* Socket used for sending RSTs */
static struct socket *tcp_socket;

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void tcp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb);
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struct inet_hashinfo __cacheline_aligned tcp_hashinfo = {
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	.lhash_lock	= __RW_LOCK_UNLOCKED(tcp_hashinfo.lhash_lock),
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	.lhash_users	= ATOMIC_INIT(0),
	.lhash_wait	= __WAIT_QUEUE_HEAD_INITIALIZER(tcp_hashinfo.lhash_wait),
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};

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static int tcp_v4_get_port(struct sock *sk, unsigned short snum)
{
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	return inet_csk_get_port(&tcp_hashinfo, sk, snum,
				 inet_csk_bind_conflict);
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}

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static void tcp_v4_hash(struct sock *sk)
{
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	inet_hash(&tcp_hashinfo, sk);
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}

void tcp_unhash(struct sock *sk)
{
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	inet_unhash(&tcp_hashinfo, sk);
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}

static inline __u32 tcp_v4_init_sequence(struct sock *sk, struct sk_buff *skb)
{
	return secure_tcp_sequence_number(skb->nh.iph->daddr,
					  skb->nh.iph->saddr,
					  skb->h.th->dest,
					  skb->h.th->source);
}

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int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
{
	const struct tcp_timewait_sock *tcptw = tcp_twsk(sktw);
	struct tcp_sock *tp = tcp_sk(sk);

	/* With PAWS, it is safe from the viewpoint
	   of data integrity. Even without PAWS it is safe provided sequence
	   spaces do not overlap i.e. at data rates <= 80Mbit/sec.

	   Actually, the idea is close to VJ's one, only timestamp cache is
	   held not per host, but per port pair and TW bucket is used as state
	   holder.

	   If TW bucket has been already destroyed we fall back to VJ's scheme
	   and use initial timestamp retrieved from peer table.
	 */
	if (tcptw->tw_ts_recent_stamp &&
	    (twp == NULL || (sysctl_tcp_tw_reuse &&
			     xtime.tv_sec - tcptw->tw_ts_recent_stamp > 1))) {
		tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2;
		if (tp->write_seq == 0)
			tp->write_seq = 1;
		tp->rx_opt.ts_recent	   = tcptw->tw_ts_recent;
		tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
		sock_hold(sktw);
		return 1;
	}

	return 0;
}

EXPORT_SYMBOL_GPL(tcp_twsk_unique);

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/* This will initiate an outgoing connection. */
int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
{
	struct inet_sock *inet = inet_sk(sk);
	struct tcp_sock *tp = tcp_sk(sk);
	struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
	struct rtable *rt;
	u32 daddr, nexthop;
	int tmp;
	int err;

	if (addr_len < sizeof(struct sockaddr_in))
		return -EINVAL;

	if (usin->sin_family != AF_INET)
		return -EAFNOSUPPORT;

	nexthop = daddr = usin->sin_addr.s_addr;
	if (inet->opt && inet->opt->srr) {
		if (!daddr)
			return -EINVAL;
		nexthop = inet->opt->faddr;
	}

	tmp = ip_route_connect(&rt, nexthop, inet->saddr,
			       RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
			       IPPROTO_TCP,
			       inet->sport, usin->sin_port, sk);
	if (tmp < 0)
		return tmp;

	if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
		ip_rt_put(rt);
		return -ENETUNREACH;
	}

	if (!inet->opt || !inet->opt->srr)
		daddr = rt->rt_dst;

	if (!inet->saddr)
		inet->saddr = rt->rt_src;
	inet->rcv_saddr = inet->saddr;

	if (tp->rx_opt.ts_recent_stamp && inet->daddr != daddr) {
		/* Reset inherited state */
		tp->rx_opt.ts_recent	   = 0;
		tp->rx_opt.ts_recent_stamp = 0;
		tp->write_seq		   = 0;
	}

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	if (tcp_death_row.sysctl_tw_recycle &&
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	    !tp->rx_opt.ts_recent_stamp && rt->rt_dst == daddr) {
		struct inet_peer *peer = rt_get_peer(rt);

		/* VJ's idea. We save last timestamp seen from
		 * the destination in peer table, when entering state TIME-WAIT
		 * and initialize rx_opt.ts_recent from it, when trying new connection.
		 */

		if (peer && peer->tcp_ts_stamp + TCP_PAWS_MSL >= xtime.tv_sec) {
			tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp;
			tp->rx_opt.ts_recent = peer->tcp_ts;
		}
	}

	inet->dport = usin->sin_port;
	inet->daddr = daddr;

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	inet_csk(sk)->icsk_ext_hdr_len = 0;
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	if (inet->opt)
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		inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
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	tp->rx_opt.mss_clamp = 536;

	/* Socket identity is still unknown (sport may be zero).
	 * However we set state to SYN-SENT and not releasing socket
	 * lock select source port, enter ourselves into the hash tables and
	 * complete initialization after this.
	 */
	tcp_set_state(sk, TCP_SYN_SENT);
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	err = inet_hash_connect(&tcp_death_row, sk);
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	if (err)
		goto failure;

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	err = ip_route_newports(&rt, IPPROTO_TCP, inet->sport, inet->dport, sk);
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	if (err)
		goto failure;

	/* OK, now commit destination to socket.  */
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	sk->sk_gso_type = SKB_GSO_TCPV4;
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	sk_setup_caps(sk, &rt->u.dst);
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	if (!tp->write_seq)
		tp->write_seq = secure_tcp_sequence_number(inet->saddr,
							   inet->daddr,
							   inet->sport,
							   usin->sin_port);

	inet->id = tp->write_seq ^ jiffies;

	err = tcp_connect(sk);
	rt = NULL;
	if (err)
		goto failure;

	return 0;

failure:
	/* This unhashes the socket and releases the local port, if necessary. */
	tcp_set_state(sk, TCP_CLOSE);
	ip_rt_put(rt);
	sk->sk_route_caps = 0;
	inet->dport = 0;
	return err;
}

/*
 * This routine does path mtu discovery as defined in RFC1191.
 */
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static void do_pmtu_discovery(struct sock *sk, struct iphdr *iph, u32 mtu)
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{
	struct dst_entry *dst;
	struct inet_sock *inet = inet_sk(sk);

	/* We are not interested in TCP_LISTEN and open_requests (SYN-ACKs
	 * send out by Linux are always <576bytes so they should go through
	 * unfragmented).
	 */
	if (sk->sk_state == TCP_LISTEN)
		return;

	/* We don't check in the destentry if pmtu discovery is forbidden
	 * on this route. We just assume that no packet_to_big packets
	 * are send back when pmtu discovery is not active.
     	 * There is a small race when the user changes this flag in the
	 * route, but I think that's acceptable.
	 */
	if ((dst = __sk_dst_check(sk, 0)) == NULL)
		return;

	dst->ops->update_pmtu(dst, mtu);

	/* Something is about to be wrong... Remember soft error
	 * for the case, if this connection will not able to recover.
	 */
	if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
		sk->sk_err_soft = EMSGSIZE;

	mtu = dst_mtu(dst);

	if (inet->pmtudisc != IP_PMTUDISC_DONT &&
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	    inet_csk(sk)->icsk_pmtu_cookie > mtu) {
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		tcp_sync_mss(sk, mtu);

		/* Resend the TCP packet because it's
		 * clear that the old packet has been
		 * dropped. This is the new "fast" path mtu
		 * discovery.
		 */
		tcp_simple_retransmit(sk);
	} /* else let the usual retransmit timer handle it */
}

/*
 * This routine is called by the ICMP module when it gets some
 * sort of error condition.  If err < 0 then the socket should
 * be closed and the error returned to the user.  If err > 0
 * it's just the icmp type << 8 | icmp code.  After adjustment
 * header points to the first 8 bytes of the tcp header.  We need
 * to find the appropriate port.
 *
 * The locking strategy used here is very "optimistic". When
 * someone else accesses the socket the ICMP is just dropped
 * and for some paths there is no check at all.
 * A more general error queue to queue errors for later handling
 * is probably better.
 *
 */

void tcp_v4_err(struct sk_buff *skb, u32 info)
{
	struct iphdr *iph = (struct iphdr *)skb->data;
	struct tcphdr *th = (struct tcphdr *)(skb->data + (iph->ihl << 2));
	struct tcp_sock *tp;
	struct inet_sock *inet;
	int type = skb->h.icmph->type;
	int code = skb->h.icmph->code;
	struct sock *sk;
	__u32 seq;
	int err;

	if (skb->len < (iph->ihl << 2) + 8) {
		ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
		return;
	}

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	sk = inet_lookup(&tcp_hashinfo, iph->daddr, th->dest, iph->saddr,
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			 th->source, inet_iif(skb));
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	if (!sk) {
		ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
		return;
	}
	if (sk->sk_state == TCP_TIME_WAIT) {
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		inet_twsk_put((struct inet_timewait_sock *)sk);
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		return;
	}

	bh_lock_sock(sk);
	/* If too many ICMPs get dropped on busy
	 * servers this needs to be solved differently.
	 */
	if (sock_owned_by_user(sk))
		NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS);

	if (sk->sk_state == TCP_CLOSE)
		goto out;

	tp = tcp_sk(sk);
	seq = ntohl(th->seq);
	if (sk->sk_state != TCP_LISTEN &&
	    !between(seq, tp->snd_una, tp->snd_nxt)) {
		NET_INC_STATS(LINUX_MIB_OUTOFWINDOWICMPS);
		goto out;
	}

	switch (type) {
	case ICMP_SOURCE_QUENCH:
		/* Just silently ignore these. */
		goto out;
	case ICMP_PARAMETERPROB:
		err = EPROTO;
		break;
	case ICMP_DEST_UNREACH:
		if (code > NR_ICMP_UNREACH)
			goto out;

		if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
			if (!sock_owned_by_user(sk))
				do_pmtu_discovery(sk, iph, info);
			goto out;
		}

		err = icmp_err_convert[code].errno;
		break;
	case ICMP_TIME_EXCEEDED:
		err = EHOSTUNREACH;
		break;
	default:
		goto out;
	}

	switch (sk->sk_state) {
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		struct request_sock *req, **prev;
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	case TCP_LISTEN:
		if (sock_owned_by_user(sk))
			goto out;

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		req = inet_csk_search_req(sk, &prev, th->dest,
					  iph->daddr, iph->saddr);
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		if (!req)
			goto out;

		/* ICMPs are not backlogged, hence we cannot get
		   an established socket here.
		 */
		BUG_TRAP(!req->sk);

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		if (seq != tcp_rsk(req)->snt_isn) {
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			NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
			goto out;
		}

		/*
		 * Still in SYN_RECV, just remove it silently.
		 * There is no good way to pass the error to the newly
		 * created socket, and POSIX does not want network
		 * errors returned from accept().
		 */
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		inet_csk_reqsk_queue_drop(sk, req, prev);
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		goto out;

	case TCP_SYN_SENT:
	case TCP_SYN_RECV:  /* Cannot happen.
			       It can f.e. if SYNs crossed.
			     */
		if (!sock_owned_by_user(sk)) {
			TCP_INC_STATS_BH(TCP_MIB_ATTEMPTFAILS);
			sk->sk_err = err;

			sk->sk_error_report(sk);

			tcp_done(sk);
		} else {
			sk->sk_err_soft = err;
		}
		goto out;
	}

	/* If we've already connected we will keep trying
	 * until we time out, or the user gives up.
	 *
	 * rfc1122 4.2.3.9 allows to consider as hard errors
	 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
	 * but it is obsoleted by pmtu discovery).
	 *
	 * Note, that in modern internet, where routing is unreliable
	 * and in each dark corner broken firewalls sit, sending random
	 * errors ordered by their masters even this two messages finally lose
	 * their original sense (even Linux sends invalid PORT_UNREACHs)
	 *
	 * Now we are in compliance with RFCs.
	 *							--ANK (980905)
	 */

	inet = inet_sk(sk);
	if (!sock_owned_by_user(sk) && inet->recverr) {
		sk->sk_err = err;
		sk->sk_error_report(sk);
	} else	{ /* Only an error on timeout */
		sk->sk_err_soft = err;
	}

out:
	bh_unlock_sock(sk);
	sock_put(sk);
}

/* This routine computes an IPv4 TCP checksum. */
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void tcp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb)
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{
	struct inet_sock *inet = inet_sk(sk);
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	struct tcphdr *th = skb->h.th;
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	if (skb->ip_summed == CHECKSUM_HW) {
		th->check = ~tcp_v4_check(th, len, inet->saddr, inet->daddr, 0);
		skb->csum = offsetof(struct tcphdr, check);
	} else {
		th->check = tcp_v4_check(th, len, inet->saddr, inet->daddr,
					 csum_partial((char *)th,
						      th->doff << 2,
						      skb->csum));
	}
}

/*
 *	This routine will send an RST to the other tcp.
 *
 *	Someone asks: why I NEVER use socket parameters (TOS, TTL etc.)
 *		      for reset.
 *	Answer: if a packet caused RST, it is not for a socket
 *		existing in our system, if it is matched to a socket,
 *		it is just duplicate segment or bug in other side's TCP.
 *		So that we build reply only basing on parameters
 *		arrived with segment.
 *	Exception: precedence violation. We do not implement it in any case.
 */

static void tcp_v4_send_reset(struct sk_buff *skb)
{
	struct tcphdr *th = skb->h.th;
	struct tcphdr rth;
	struct ip_reply_arg arg;

	/* Never send a reset in response to a reset. */
	if (th->rst)
		return;

	if (((struct rtable *)skb->dst)->rt_type != RTN_LOCAL)
		return;

	/* Swap the send and the receive. */
	memset(&rth, 0, sizeof(struct tcphdr));
	rth.dest   = th->source;
	rth.source = th->dest;
	rth.doff   = sizeof(struct tcphdr) / 4;
	rth.rst    = 1;

	if (th->ack) {
		rth.seq = th->ack_seq;
	} else {
		rth.ack = 1;
		rth.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin +
				    skb->len - (th->doff << 2));
	}

	memset(&arg, 0, sizeof arg);
	arg.iov[0].iov_base = (unsigned char *)&rth;
	arg.iov[0].iov_len  = sizeof rth;
	arg.csum = csum_tcpudp_nofold(skb->nh.iph->daddr,
				      skb->nh.iph->saddr, /*XXX*/
				      sizeof(struct tcphdr), IPPROTO_TCP, 0);
	arg.csumoffset = offsetof(struct tcphdr, check) / 2;

	ip_send_reply(tcp_socket->sk, skb, &arg, sizeof rth);

	TCP_INC_STATS_BH(TCP_MIB_OUTSEGS);
	TCP_INC_STATS_BH(TCP_MIB_OUTRSTS);
}

/* The code following below sending ACKs in SYN-RECV and TIME-WAIT states
   outside socket context is ugly, certainly. What can I do?
 */

static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
			    u32 win, u32 ts)
{
	struct tcphdr *th = skb->h.th;
	struct {
		struct tcphdr th;
		u32 tsopt[3];
	} rep;
	struct ip_reply_arg arg;

	memset(&rep.th, 0, sizeof(struct tcphdr));
	memset(&arg, 0, sizeof arg);

	arg.iov[0].iov_base = (unsigned char *)&rep;
	arg.iov[0].iov_len  = sizeof(rep.th);
	if (ts) {
		rep.tsopt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
				     (TCPOPT_TIMESTAMP << 8) |
				     TCPOLEN_TIMESTAMP);
		rep.tsopt[1] = htonl(tcp_time_stamp);
		rep.tsopt[2] = htonl(ts);
		arg.iov[0].iov_len = sizeof(rep);
	}

	/* Swap the send and the receive. */
	rep.th.dest    = th->source;
	rep.th.source  = th->dest;
	rep.th.doff    = arg.iov[0].iov_len / 4;
	rep.th.seq     = htonl(seq);
	rep.th.ack_seq = htonl(ack);
	rep.th.ack     = 1;
	rep.th.window  = htons(win);

	arg.csum = csum_tcpudp_nofold(skb->nh.iph->daddr,
				      skb->nh.iph->saddr, /*XXX*/
				      arg.iov[0].iov_len, IPPROTO_TCP, 0);
	arg.csumoffset = offsetof(struct tcphdr, check) / 2;

	ip_send_reply(tcp_socket->sk, skb, &arg, arg.iov[0].iov_len);

	TCP_INC_STATS_BH(TCP_MIB_OUTSEGS);
}

static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
{
603 604
	struct inet_timewait_sock *tw = inet_twsk(sk);
	const struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
L
Linus Torvalds 已提交
605

606 607
	tcp_v4_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
			tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale, tcptw->tw_ts_recent);
L
Linus Torvalds 已提交
608

609
	inet_twsk_put(tw);
L
Linus Torvalds 已提交
610 611
}

612
static void tcp_v4_reqsk_send_ack(struct sk_buff *skb, struct request_sock *req)
L
Linus Torvalds 已提交
613
{
614
	tcp_v4_send_ack(skb, tcp_rsk(req)->snt_isn + 1, tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd,
L
Linus Torvalds 已提交
615 616 617 618 619
			req->ts_recent);
}

/*
 *	Send a SYN-ACK after having received an ACK.
620
 *	This still operates on a request_sock only, not on a big
L
Linus Torvalds 已提交
621 622
 *	socket.
 */
623
static int tcp_v4_send_synack(struct sock *sk, struct request_sock *req,
L
Linus Torvalds 已提交
624 625
			      struct dst_entry *dst)
{
626
	const struct inet_request_sock *ireq = inet_rsk(req);
L
Linus Torvalds 已提交
627 628 629 630
	int err = -1;
	struct sk_buff * skb;

	/* First, grab a route. */
631
	if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
L
Linus Torvalds 已提交
632 633 634 635 636 637 638 639
		goto out;

	skb = tcp_make_synack(sk, dst, req);

	if (skb) {
		struct tcphdr *th = skb->h.th;

		th->check = tcp_v4_check(th, skb->len,
640 641
					 ireq->loc_addr,
					 ireq->rmt_addr,
L
Linus Torvalds 已提交
642 643 644
					 csum_partial((char *)th, skb->len,
						      skb->csum));

645 646 647
		err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
					    ireq->rmt_addr,
					    ireq->opt);
L
Linus Torvalds 已提交
648 649 650 651 652 653 654 655 656 657
		if (err == NET_XMIT_CN)
			err = 0;
	}

out:
	dst_release(dst);
	return err;
}

/*
658
 *	IPv4 request_sock destructor.
L
Linus Torvalds 已提交
659
 */
660
static void tcp_v4_reqsk_destructor(struct request_sock *req)
L
Linus Torvalds 已提交
661
{
J
Jesper Juhl 已提交
662
	kfree(inet_rsk(req)->opt);
L
Linus Torvalds 已提交
663 664
}

665
#ifdef CONFIG_SYN_COOKIES
S
Stephen Hemminger 已提交
666
static void syn_flood_warning(struct sk_buff *skb)
L
Linus Torvalds 已提交
667 668 669 670 671 672 673 674 675 676
{
	static unsigned long warntime;

	if (time_after(jiffies, (warntime + HZ * 60))) {
		warntime = jiffies;
		printk(KERN_INFO
		       "possible SYN flooding on port %d. Sending cookies.\n",
		       ntohs(skb->h.th->dest));
	}
}
677
#endif
L
Linus Torvalds 已提交
678 679

/*
680
 * Save and compile IPv4 options into the request_sock if needed.
L
Linus Torvalds 已提交
681
 */
S
Stephen Hemminger 已提交
682 683
static struct ip_options *tcp_v4_save_options(struct sock *sk,
					      struct sk_buff *skb)
L
Linus Torvalds 已提交
684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700
{
	struct ip_options *opt = &(IPCB(skb)->opt);
	struct ip_options *dopt = NULL;

	if (opt && opt->optlen) {
		int opt_size = optlength(opt);
		dopt = kmalloc(opt_size, GFP_ATOMIC);
		if (dopt) {
			if (ip_options_echo(dopt, skb)) {
				kfree(dopt);
				dopt = NULL;
			}
		}
	}
	return dopt;
}

701
struct request_sock_ops tcp_request_sock_ops = {
L
Linus Torvalds 已提交
702
	.family		=	PF_INET,
703
	.obj_size	=	sizeof(struct tcp_request_sock),
L
Linus Torvalds 已提交
704
	.rtx_syn_ack	=	tcp_v4_send_synack,
705 706
	.send_ack	=	tcp_v4_reqsk_send_ack,
	.destructor	=	tcp_v4_reqsk_destructor,
L
Linus Torvalds 已提交
707 708 709
	.send_reset	=	tcp_v4_send_reset,
};

710 711 712 713 714
static struct timewait_sock_ops tcp_timewait_sock_ops = {
	.twsk_obj_size	= sizeof(struct tcp_timewait_sock),
	.twsk_unique	= tcp_twsk_unique,
};

L
Linus Torvalds 已提交
715 716
int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
{
717
	struct inet_request_sock *ireq;
L
Linus Torvalds 已提交
718
	struct tcp_options_received tmp_opt;
719
	struct request_sock *req;
L
Linus Torvalds 已提交
720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738
	__u32 saddr = skb->nh.iph->saddr;
	__u32 daddr = skb->nh.iph->daddr;
	__u32 isn = TCP_SKB_CB(skb)->when;
	struct dst_entry *dst = NULL;
#ifdef CONFIG_SYN_COOKIES
	int want_cookie = 0;
#else
#define want_cookie 0 /* Argh, why doesn't gcc optimize this :( */
#endif

	/* Never answer to SYNs send to broadcast or multicast */
	if (((struct rtable *)skb->dst)->rt_flags &
	    (RTCF_BROADCAST | RTCF_MULTICAST))
		goto drop;

	/* TW buckets are converted to open requests without
	 * limitations, they conserve resources and peer is
	 * evidently real one.
	 */
739
	if (inet_csk_reqsk_queue_is_full(sk) && !isn) {
L
Linus Torvalds 已提交
740 741 742 743 744 745 746 747 748 749 750 751 752
#ifdef CONFIG_SYN_COOKIES
		if (sysctl_tcp_syncookies) {
			want_cookie = 1;
		} else
#endif
		goto drop;
	}

	/* Accept backlog is full. If we have already queued enough
	 * of warm entries in syn queue, drop request. It is better than
	 * clogging syn queue with openreqs with exponentially increasing
	 * timeout.
	 */
753
	if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
L
Linus Torvalds 已提交
754 755
		goto drop;

756
	req = reqsk_alloc(&tcp_request_sock_ops);
L
Linus Torvalds 已提交
757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783
	if (!req)
		goto drop;

	tcp_clear_options(&tmp_opt);
	tmp_opt.mss_clamp = 536;
	tmp_opt.user_mss  = tcp_sk(sk)->rx_opt.user_mss;

	tcp_parse_options(skb, &tmp_opt, 0);

	if (want_cookie) {
		tcp_clear_options(&tmp_opt);
		tmp_opt.saw_tstamp = 0;
	}

	if (tmp_opt.saw_tstamp && !tmp_opt.rcv_tsval) {
		/* Some OSes (unknown ones, but I see them on web server, which
		 * contains information interesting only for windows'
		 * users) do not send their stamp in SYN. It is easy case.
		 * We simply do not advertise TS support.
		 */
		tmp_opt.saw_tstamp = 0;
		tmp_opt.tstamp_ok  = 0;
	}
	tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;

	tcp_openreq_init(req, &tmp_opt, skb);

784 785 786 787
	ireq = inet_rsk(req);
	ireq->loc_addr = daddr;
	ireq->rmt_addr = saddr;
	ireq->opt = tcp_v4_save_options(sk, skb);
L
Linus Torvalds 已提交
788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808
	if (!want_cookie)
		TCP_ECN_create_request(req, skb->h.th);

	if (want_cookie) {
#ifdef CONFIG_SYN_COOKIES
		syn_flood_warning(skb);
#endif
		isn = cookie_v4_init_sequence(sk, skb, &req->mss);
	} else if (!isn) {
		struct inet_peer *peer = NULL;

		/* VJ's idea. We save last timestamp seen
		 * from the destination in peer table, when entering
		 * state TIME-WAIT, and check against it before
		 * accepting new connection request.
		 *
		 * If "isn" is not zero, this request hit alive
		 * timewait bucket, so that all the necessary checks
		 * are made in the function processing timewait state.
		 */
		if (tmp_opt.saw_tstamp &&
809
		    tcp_death_row.sysctl_tw_recycle &&
810
		    (dst = inet_csk_route_req(sk, req)) != NULL &&
L
Linus Torvalds 已提交
811 812 813 814 815 816 817 818 819 820 821 822
		    (peer = rt_get_peer((struct rtable *)dst)) != NULL &&
		    peer->v4daddr == saddr) {
			if (xtime.tv_sec < peer->tcp_ts_stamp + TCP_PAWS_MSL &&
			    (s32)(peer->tcp_ts - req->ts_recent) >
							TCP_PAWS_WINDOW) {
				NET_INC_STATS_BH(LINUX_MIB_PAWSPASSIVEREJECTED);
				dst_release(dst);
				goto drop_and_free;
			}
		}
		/* Kill the following clause, if you dislike this way. */
		else if (!sysctl_tcp_syncookies &&
823
			 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
L
Linus Torvalds 已提交
824 825 826 827 828 829 830 831 832 833
			  (sysctl_max_syn_backlog >> 2)) &&
			 (!peer || !peer->tcp_ts_stamp) &&
			 (!dst || !dst_metric(dst, RTAX_RTT))) {
			/* Without syncookies last quarter of
			 * backlog is filled with destinations,
			 * proven to be alive.
			 * It means that we continue to communicate
			 * to destinations, already remembered
			 * to the moment of synflood.
			 */
834 835 836 837
			LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open "
				       "request from %u.%u.%u.%u/%u\n",
				       NIPQUAD(saddr),
				       ntohs(skb->h.th->source));
L
Linus Torvalds 已提交
838 839 840 841 842 843
			dst_release(dst);
			goto drop_and_free;
		}

		isn = tcp_v4_init_sequence(sk, skb);
	}
844
	tcp_rsk(req)->snt_isn = isn;
L
Linus Torvalds 已提交
845 846 847 848 849

	if (tcp_v4_send_synack(sk, req, dst))
		goto drop_and_free;

	if (want_cookie) {
850
	   	reqsk_free(req);
L
Linus Torvalds 已提交
851
	} else {
852
		inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
L
Linus Torvalds 已提交
853 854 855 856
	}
	return 0;

drop_and_free:
857
	reqsk_free(req);
L
Linus Torvalds 已提交
858 859 860 861 862 863 864 865 866 867 868
drop:
	TCP_INC_STATS_BH(TCP_MIB_ATTEMPTFAILS);
	return 0;
}


/*
 * The three way handshake has completed - we got a valid synack -
 * now create the new socket.
 */
struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
869
				  struct request_sock *req,
L
Linus Torvalds 已提交
870 871
				  struct dst_entry *dst)
{
872
	struct inet_request_sock *ireq;
L
Linus Torvalds 已提交
873 874 875 876 877 878 879
	struct inet_sock *newinet;
	struct tcp_sock *newtp;
	struct sock *newsk;

	if (sk_acceptq_is_full(sk))
		goto exit_overflow;

880
	if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
L
Linus Torvalds 已提交
881 882 883 884 885 886
		goto exit;

	newsk = tcp_create_openreq_child(sk, req, skb);
	if (!newsk)
		goto exit;

887
	newsk->sk_gso_type = SKB_GSO_TCPV4;
888
	sk_setup_caps(newsk, dst);
L
Linus Torvalds 已提交
889 890 891

	newtp		      = tcp_sk(newsk);
	newinet		      = inet_sk(newsk);
892 893 894 895 896 897
	ireq		      = inet_rsk(req);
	newinet->daddr	      = ireq->rmt_addr;
	newinet->rcv_saddr    = ireq->loc_addr;
	newinet->saddr	      = ireq->loc_addr;
	newinet->opt	      = ireq->opt;
	ireq->opt	      = NULL;
898
	newinet->mc_index     = inet_iif(skb);
L
Linus Torvalds 已提交
899
	newinet->mc_ttl	      = skb->nh.iph->ttl;
900
	inet_csk(newsk)->icsk_ext_hdr_len = 0;
L
Linus Torvalds 已提交
901
	if (newinet->opt)
902
		inet_csk(newsk)->icsk_ext_hdr_len = newinet->opt->optlen;
L
Linus Torvalds 已提交
903 904
	newinet->id = newtp->write_seq ^ jiffies;

J
John Heffner 已提交
905
	tcp_mtup_init(newsk);
L
Linus Torvalds 已提交
906 907 908 909
	tcp_sync_mss(newsk, dst_mtu(dst));
	newtp->advmss = dst_metric(dst, RTAX_ADVMSS);
	tcp_initialize_rcv_mss(newsk);

910
	__inet_hash(&tcp_hashinfo, newsk, 0);
911
	__inet_inherit_port(&tcp_hashinfo, sk, newsk);
L
Linus Torvalds 已提交
912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927

	return newsk;

exit_overflow:
	NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS);
exit:
	NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS);
	dst_release(dst);
	return NULL;
}

static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
{
	struct tcphdr *th = skb->h.th;
	struct iphdr *iph = skb->nh.iph;
	struct sock *nsk;
928
	struct request_sock **prev;
L
Linus Torvalds 已提交
929
	/* Find possible connection requests. */
930 931
	struct request_sock *req = inet_csk_search_req(sk, &prev, th->source,
						       iph->saddr, iph->daddr);
L
Linus Torvalds 已提交
932 933 934
	if (req)
		return tcp_check_req(sk, skb, req, prev);

935 936
	nsk = __inet_lookup_established(&tcp_hashinfo, skb->nh.iph->saddr,
					th->source, skb->nh.iph->daddr,
937
					ntohs(th->dest), inet_iif(skb));
L
Linus Torvalds 已提交
938 939 940 941 942 943

	if (nsk) {
		if (nsk->sk_state != TCP_TIME_WAIT) {
			bh_lock_sock(nsk);
			return nsk;
		}
944
		inet_twsk_put((struct inet_timewait_sock *)nsk);
L
Linus Torvalds 已提交
945 946 947 948 949 950 951 952 953 954 955 956 957 958
		return NULL;
	}

#ifdef CONFIG_SYN_COOKIES
	if (!th->rst && !th->syn && th->ack)
		sk = cookie_v4_check(sk, skb, &(IPCB(skb)->opt));
#endif
	return sk;
}

static int tcp_v4_checksum_init(struct sk_buff *skb)
{
	if (skb->ip_summed == CHECKSUM_HW) {
		if (!tcp_v4_check(skb->h.th, skb->len, skb->nh.iph->saddr,
959 960
				  skb->nh.iph->daddr, skb->csum)) {
			skb->ip_summed = CHECKSUM_UNNECESSARY;
L
Linus Torvalds 已提交
961
			return 0;
962
		}
L
Linus Torvalds 已提交
963
	}
964 965 966 967

	skb->csum = csum_tcpudp_nofold(skb->nh.iph->saddr, skb->nh.iph->daddr,
				       skb->len, IPPROTO_TCP, 0);

L
Linus Torvalds 已提交
968
	if (skb->len <= 76) {
969
		return __skb_checksum_complete(skb);
L
Linus Torvalds 已提交
970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057
	}
	return 0;
}


/* The socket must have it's spinlock held when we get
 * here.
 *
 * We have a potential double-lock case here, so even when
 * doing backlog processing we use the BH locking scheme.
 * This is because we cannot sleep with the original spinlock
 * held.
 */
int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
{
	if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
		TCP_CHECK_TIMER(sk);
		if (tcp_rcv_established(sk, skb, skb->h.th, skb->len))
			goto reset;
		TCP_CHECK_TIMER(sk);
		return 0;
	}

	if (skb->len < (skb->h.th->doff << 2) || tcp_checksum_complete(skb))
		goto csum_err;

	if (sk->sk_state == TCP_LISTEN) {
		struct sock *nsk = tcp_v4_hnd_req(sk, skb);
		if (!nsk)
			goto discard;

		if (nsk != sk) {
			if (tcp_child_process(sk, nsk, skb))
				goto reset;
			return 0;
		}
	}

	TCP_CHECK_TIMER(sk);
	if (tcp_rcv_state_process(sk, skb, skb->h.th, skb->len))
		goto reset;
	TCP_CHECK_TIMER(sk);
	return 0;

reset:
	tcp_v4_send_reset(skb);
discard:
	kfree_skb(skb);
	/* Be careful here. If this function gets more complicated and
	 * gcc suffers from register pressure on the x86, sk (in %ebx)
	 * might be destroyed here. This current version compiles correctly,
	 * but you have been warned.
	 */
	return 0;

csum_err:
	TCP_INC_STATS_BH(TCP_MIB_INERRS);
	goto discard;
}

/*
 *	From tcp_input.c
 */

int tcp_v4_rcv(struct sk_buff *skb)
{
	struct tcphdr *th;
	struct sock *sk;
	int ret;

	if (skb->pkt_type != PACKET_HOST)
		goto discard_it;

	/* Count it even if it's bad */
	TCP_INC_STATS_BH(TCP_MIB_INSEGS);

	if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
		goto discard_it;

	th = skb->h.th;

	if (th->doff < sizeof(struct tcphdr) / 4)
		goto bad_packet;
	if (!pskb_may_pull(skb, th->doff * 4))
		goto discard_it;

	/* An explanation is required here, I think.
	 * Packet length and doff are validated by header prediction,
S
Stephen Hemminger 已提交
1058
	 * provided case of th->doff==0 is eliminated.
L
Linus Torvalds 已提交
1059 1060
	 * So, we defer the checks. */
	if ((skb->ip_summed != CHECKSUM_UNNECESSARY &&
1061
	     tcp_v4_checksum_init(skb)))
L
Linus Torvalds 已提交
1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072
		goto bad_packet;

	th = skb->h.th;
	TCP_SKB_CB(skb)->seq = ntohl(th->seq);
	TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
				    skb->len - th->doff * 4);
	TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
	TCP_SKB_CB(skb)->when	 = 0;
	TCP_SKB_CB(skb)->flags	 = skb->nh.iph->tos;
	TCP_SKB_CB(skb)->sacked	 = 0;

1073 1074
	sk = __inet_lookup(&tcp_hashinfo, skb->nh.iph->saddr, th->source,
			   skb->nh.iph->daddr, ntohs(th->dest),
1075
			   inet_iif(skb));
L
Linus Torvalds 已提交
1076 1077 1078 1079 1080 1081 1082 1083 1084 1085

	if (!sk)
		goto no_tcp_socket;

process:
	if (sk->sk_state == TCP_TIME_WAIT)
		goto do_time_wait;

	if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
		goto discard_and_relse;
1086
	nf_reset(skb);
L
Linus Torvalds 已提交
1087 1088 1089 1090 1091 1092

	if (sk_filter(sk, skb, 0))
		goto discard_and_relse;

	skb->dev = NULL;

1093
	bh_lock_sock_nested(sk);
L
Linus Torvalds 已提交
1094 1095
	ret = 0;
	if (!sock_owned_by_user(sk)) {
C
Chris Leech 已提交
1096 1097 1098 1099 1100
#ifdef CONFIG_NET_DMA
		struct tcp_sock *tp = tcp_sk(sk);
		if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
			tp->ucopy.dma_chan = get_softnet_dma();
		if (tp->ucopy.dma_chan)
L
Linus Torvalds 已提交
1101
			ret = tcp_v4_do_rcv(sk, skb);
C
Chris Leech 已提交
1102 1103 1104 1105 1106 1107
		else
#endif
		{
			if (!tcp_prequeue(sk, skb))
			ret = tcp_v4_do_rcv(sk, skb);
		}
L
Linus Torvalds 已提交
1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137
	} else
		sk_add_backlog(sk, skb);
	bh_unlock_sock(sk);

	sock_put(sk);

	return ret;

no_tcp_socket:
	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
		goto discard_it;

	if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
bad_packet:
		TCP_INC_STATS_BH(TCP_MIB_INERRS);
	} else {
		tcp_v4_send_reset(skb);
	}

discard_it:
	/* Discard frame. */
	kfree_skb(skb);
  	return 0;

discard_and_relse:
	sock_put(sk);
	goto discard_it;

do_time_wait:
	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1138
		inet_twsk_put((struct inet_timewait_sock *) sk);
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		goto discard_it;
	}

	if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
		TCP_INC_STATS_BH(TCP_MIB_INERRS);
1144
		inet_twsk_put((struct inet_timewait_sock *) sk);
L
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		goto discard_it;
	}
1147 1148
	switch (tcp_timewait_state_process((struct inet_timewait_sock *)sk,
					   skb, th)) {
L
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	case TCP_TW_SYN: {
1150 1151 1152
		struct sock *sk2 = inet_lookup_listener(&tcp_hashinfo,
							skb->nh.iph->daddr,
							ntohs(th->dest),
1153
							inet_iif(skb));
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		if (sk2) {
1155 1156
			inet_twsk_deschedule((struct inet_timewait_sock *)sk,
					     &tcp_death_row);
1157
			inet_twsk_put((struct inet_timewait_sock *)sk);
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			sk = sk2;
			goto process;
		}
		/* Fall through to ACK */
	}
	case TCP_TW_ACK:
		tcp_v4_timewait_ack(sk, skb);
		break;
	case TCP_TW_RST:
		goto no_tcp_socket;
	case TCP_TW_SUCCESS:;
	}
	goto discard_it;
}

/* VJ's idea. Save last timestamp seen from this destination
 * and hold it at least for normal timewait interval to use for duplicate
 * segment detection in subsequent connections, before they enter synchronized
 * state.
 */

int tcp_v4_remember_stamp(struct sock *sk)
{
	struct inet_sock *inet = inet_sk(sk);
	struct tcp_sock *tp = tcp_sk(sk);
	struct rtable *rt = (struct rtable *)__sk_dst_get(sk);
	struct inet_peer *peer = NULL;
	int release_it = 0;

	if (!rt || rt->rt_dst != inet->daddr) {
		peer = inet_getpeer(inet->daddr, 1);
		release_it = 1;
	} else {
		if (!rt->peer)
			rt_bind_peer(rt, 1);
		peer = rt->peer;
	}

	if (peer) {
		if ((s32)(peer->tcp_ts - tp->rx_opt.ts_recent) <= 0 ||
		    (peer->tcp_ts_stamp + TCP_PAWS_MSL < xtime.tv_sec &&
		     peer->tcp_ts_stamp <= tp->rx_opt.ts_recent_stamp)) {
			peer->tcp_ts_stamp = tp->rx_opt.ts_recent_stamp;
			peer->tcp_ts = tp->rx_opt.ts_recent;
		}
		if (release_it)
			inet_putpeer(peer);
		return 1;
	}

	return 0;
}

1211
int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw)
L
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{
1213
	struct inet_peer *peer = inet_getpeer(tw->tw_daddr, 1);
L
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	if (peer) {
1216 1217 1218
		const struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);

		if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 ||
L
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1219
		    (peer->tcp_ts_stamp + TCP_PAWS_MSL < xtime.tv_sec &&
1220 1221 1222
		     peer->tcp_ts_stamp <= tcptw->tw_ts_recent_stamp)) {
			peer->tcp_ts_stamp = tcptw->tw_ts_recent_stamp;
			peer->tcp_ts	   = tcptw->tw_ts_recent;
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		}
		inet_putpeer(peer);
		return 1;
	}

	return 0;
}

1231
struct inet_connection_sock_af_ops ipv4_specific = {
1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242
	.queue_xmit	   = ip_queue_xmit,
	.send_check	   = tcp_v4_send_check,
	.rebuild_header	   = inet_sk_rebuild_header,
	.conn_request	   = tcp_v4_conn_request,
	.syn_recv_sock	   = tcp_v4_syn_recv_sock,
	.remember_stamp	   = tcp_v4_remember_stamp,
	.net_header_len	   = sizeof(struct iphdr),
	.setsockopt	   = ip_setsockopt,
	.getsockopt	   = ip_getsockopt,
	.addr2sockaddr	   = inet_csk_addr2sockaddr,
	.sockaddr_len	   = sizeof(struct sockaddr_in),
1243
#ifdef CONFIG_COMPAT
1244 1245
	.compat_setsockopt = compat_ip_setsockopt,
	.compat_getsockopt = compat_ip_getsockopt,
1246
#endif
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};

/* NOTE: A lot of things set to zero explicitly by call to
 *       sk_alloc() so need not be done here.
 */
static int tcp_v4_init_sock(struct sock *sk)
{
1254
	struct inet_connection_sock *icsk = inet_csk(sk);
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	struct tcp_sock *tp = tcp_sk(sk);

	skb_queue_head_init(&tp->out_of_order_queue);
	tcp_init_xmit_timers(sk);
	tcp_prequeue_init(tp);

1261
	icsk->icsk_rto = TCP_TIMEOUT_INIT;
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	tp->mdev = TCP_TIMEOUT_INIT;

	/* So many TCP implementations out there (incorrectly) count the
	 * initial SYN frame in their delayed-ACK and congestion control
	 * algorithms that we must have the following bandaid to talk
	 * efficiently to them.  -DaveM
	 */
	tp->snd_cwnd = 2;

	/* See draft-stevens-tcpca-spec-01 for discussion of the
	 * initialization of these values.
	 */
	tp->snd_ssthresh = 0x7fffffff;	/* Infinity */
	tp->snd_cwnd_clamp = ~0;
1276
	tp->mss_cache = 536;
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	tp->reordering = sysctl_tcp_reordering;
1279
	icsk->icsk_ca_ops = &tcp_init_congestion_ops;
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1280 1281 1282 1283 1284 1285

	sk->sk_state = TCP_CLOSE;

	sk->sk_write_space = sk_stream_write_space;
	sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);

1286
	icsk->icsk_af_ops = &ipv4_specific;
1287
	icsk->icsk_sync_mss = tcp_sync_mss;
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	sk->sk_sndbuf = sysctl_tcp_wmem[1];
	sk->sk_rcvbuf = sysctl_tcp_rmem[1];

	atomic_inc(&tcp_sockets_allocated);

	return 0;
}

int tcp_v4_destroy_sock(struct sock *sk)
{
	struct tcp_sock *tp = tcp_sk(sk);

	tcp_clear_xmit_timers(sk);

1303
	tcp_cleanup_congestion_control(sk);
1304

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	/* Cleanup up the write buffer. */
  	sk_stream_writequeue_purge(sk);

	/* Cleans up our, hopefully empty, out_of_order_queue. */
  	__skb_queue_purge(&tp->out_of_order_queue);

C
Chris Leech 已提交
1311 1312 1313 1314 1315
#ifdef CONFIG_NET_DMA
	/* Cleans up our sk_async_wait_queue */
  	__skb_queue_purge(&sk->sk_async_wait_queue);
#endif

L
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1316 1317 1318 1319
	/* Clean prequeue, it must be empty really */
	__skb_queue_purge(&tp->ucopy.prequeue);

	/* Clean up a referenced TCP bind bucket. */
1320
	if (inet_csk(sk)->icsk_bind_hash)
1321
		inet_put_port(&tcp_hashinfo, sk);
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1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340

	/*
	 * If sendmsg cached page exists, toss it.
	 */
	if (sk->sk_sndmsg_page) {
		__free_page(sk->sk_sndmsg_page);
		sk->sk_sndmsg_page = NULL;
	}

	atomic_dec(&tcp_sockets_allocated);

	return 0;
}

EXPORT_SYMBOL(tcp_v4_destroy_sock);

#ifdef CONFIG_PROC_FS
/* Proc filesystem TCP sock list dumping. */

1341
static inline struct inet_timewait_sock *tw_head(struct hlist_head *head)
L
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1342 1343
{
	return hlist_empty(head) ? NULL :
1344
		list_entry(head->first, struct inet_timewait_sock, tw_node);
L
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1345 1346
}

1347
static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw)
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{
	return tw->tw_node.next ?
		hlist_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL;
}

static void *listening_get_next(struct seq_file *seq, void *cur)
{
1355
	struct inet_connection_sock *icsk;
L
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	struct hlist_node *node;
	struct sock *sk = cur;
	struct tcp_iter_state* st = seq->private;

	if (!sk) {
		st->bucket = 0;
1362
		sk = sk_head(&tcp_hashinfo.listening_hash[0]);
L
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1363 1364 1365 1366 1367 1368
		goto get_sk;
	}

	++st->num;

	if (st->state == TCP_SEQ_STATE_OPENREQ) {
1369
		struct request_sock *req = cur;
L
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1370

1371
	       	icsk = inet_csk(st->syn_wait_sk);
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1372 1373 1374
		req = req->dl_next;
		while (1) {
			while (req) {
1375
				if (req->rsk_ops->family == st->family) {
L
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1376 1377 1378 1379 1380 1381 1382 1383
					cur = req;
					goto out;
				}
				req = req->dl_next;
			}
			if (++st->sbucket >= TCP_SYNQ_HSIZE)
				break;
get_req:
1384
			req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];
L
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		}
		sk	  = sk_next(st->syn_wait_sk);
		st->state = TCP_SEQ_STATE_LISTENING;
1388
		read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
L
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1389
	} else {
1390 1391 1392
	       	icsk = inet_csk(sk);
		read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
		if (reqsk_queue_len(&icsk->icsk_accept_queue))
L
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1393
			goto start_req;
1394
		read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
L
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1395 1396 1397 1398 1399 1400 1401 1402
		sk = sk_next(sk);
	}
get_sk:
	sk_for_each_from(sk, node) {
		if (sk->sk_family == st->family) {
			cur = sk;
			goto out;
		}
1403 1404 1405
	       	icsk = inet_csk(sk);
		read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
		if (reqsk_queue_len(&icsk->icsk_accept_queue)) {
L
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start_req:
			st->uid		= sock_i_uid(sk);
			st->syn_wait_sk = sk;
			st->state	= TCP_SEQ_STATE_OPENREQ;
			st->sbucket	= 0;
			goto get_req;
		}
1413
		read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
L
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1414
	}
1415
	if (++st->bucket < INET_LHTABLE_SIZE) {
1416
		sk = sk_head(&tcp_hashinfo.listening_hash[st->bucket]);
L
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1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439
		goto get_sk;
	}
	cur = NULL;
out:
	return cur;
}

static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
{
	void *rc = listening_get_next(seq, NULL);

	while (rc && *pos) {
		rc = listening_get_next(seq, rc);
		--*pos;
	}
	return rc;
}

static void *established_get_first(struct seq_file *seq)
{
	struct tcp_iter_state* st = seq->private;
	void *rc = NULL;

1440
	for (st->bucket = 0; st->bucket < tcp_hashinfo.ehash_size; ++st->bucket) {
L
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1441 1442
		struct sock *sk;
		struct hlist_node *node;
1443
		struct inet_timewait_sock *tw;
L
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1444 1445 1446 1447

		/* We can reschedule _before_ having picked the target: */
		cond_resched_softirq();

1448 1449
		read_lock(&tcp_hashinfo.ehash[st->bucket].lock);
		sk_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
L
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1450 1451 1452 1453 1454 1455 1456
			if (sk->sk_family != st->family) {
				continue;
			}
			rc = sk;
			goto out;
		}
		st->state = TCP_SEQ_STATE_TIME_WAIT;
1457 1458
		inet_twsk_for_each(tw, node,
				   &tcp_hashinfo.ehash[st->bucket + tcp_hashinfo.ehash_size].chain) {
L
Linus Torvalds 已提交
1459 1460 1461 1462 1463 1464
			if (tw->tw_family != st->family) {
				continue;
			}
			rc = tw;
			goto out;
		}
1465
		read_unlock(&tcp_hashinfo.ehash[st->bucket].lock);
L
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1466 1467 1468 1469 1470 1471 1472 1473 1474
		st->state = TCP_SEQ_STATE_ESTABLISHED;
	}
out:
	return rc;
}

static void *established_get_next(struct seq_file *seq, void *cur)
{
	struct sock *sk = cur;
1475
	struct inet_timewait_sock *tw;
L
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1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491
	struct hlist_node *node;
	struct tcp_iter_state* st = seq->private;

	++st->num;

	if (st->state == TCP_SEQ_STATE_TIME_WAIT) {
		tw = cur;
		tw = tw_next(tw);
get_tw:
		while (tw && tw->tw_family != st->family) {
			tw = tw_next(tw);
		}
		if (tw) {
			cur = tw;
			goto out;
		}
1492
		read_unlock(&tcp_hashinfo.ehash[st->bucket].lock);
L
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1493 1494 1495 1496 1497
		st->state = TCP_SEQ_STATE_ESTABLISHED;

		/* We can reschedule between buckets: */
		cond_resched_softirq();

1498 1499 1500
		if (++st->bucket < tcp_hashinfo.ehash_size) {
			read_lock(&tcp_hashinfo.ehash[st->bucket].lock);
			sk = sk_head(&tcp_hashinfo.ehash[st->bucket].chain);
L
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1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513
		} else {
			cur = NULL;
			goto out;
		}
	} else
		sk = sk_next(sk);

	sk_for_each_from(sk, node) {
		if (sk->sk_family == st->family)
			goto found;
	}

	st->state = TCP_SEQ_STATE_TIME_WAIT;
1514
	tw = tw_head(&tcp_hashinfo.ehash[st->bucket + tcp_hashinfo.ehash_size].chain);
L
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1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537
	goto get_tw;
found:
	cur = sk;
out:
	return cur;
}

static void *established_get_idx(struct seq_file *seq, loff_t pos)
{
	void *rc = established_get_first(seq);

	while (rc && pos) {
		rc = established_get_next(seq, rc);
		--pos;
	}		
	return rc;
}

static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
{
	void *rc;
	struct tcp_iter_state* st = seq->private;

1538
	inet_listen_lock(&tcp_hashinfo);
L
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1539 1540 1541 1542
	st->state = TCP_SEQ_STATE_LISTENING;
	rc	  = listening_get_idx(seq, &pos);

	if (!rc) {
1543
		inet_listen_unlock(&tcp_hashinfo);
L
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1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575
		local_bh_disable();
		st->state = TCP_SEQ_STATE_ESTABLISHED;
		rc	  = established_get_idx(seq, pos);
	}

	return rc;
}

static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
{
	struct tcp_iter_state* st = seq->private;
	st->state = TCP_SEQ_STATE_LISTENING;
	st->num = 0;
	return *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
}

static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
	void *rc = NULL;
	struct tcp_iter_state* st;

	if (v == SEQ_START_TOKEN) {
		rc = tcp_get_idx(seq, 0);
		goto out;
	}
	st = seq->private;

	switch (st->state) {
	case TCP_SEQ_STATE_OPENREQ:
	case TCP_SEQ_STATE_LISTENING:
		rc = listening_get_next(seq, v);
		if (!rc) {
1576
			inet_listen_unlock(&tcp_hashinfo);
L
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1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598
			local_bh_disable();
			st->state = TCP_SEQ_STATE_ESTABLISHED;
			rc	  = established_get_first(seq);
		}
		break;
	case TCP_SEQ_STATE_ESTABLISHED:
	case TCP_SEQ_STATE_TIME_WAIT:
		rc = established_get_next(seq, v);
		break;
	}
out:
	++*pos;
	return rc;
}

static void tcp_seq_stop(struct seq_file *seq, void *v)
{
	struct tcp_iter_state* st = seq->private;

	switch (st->state) {
	case TCP_SEQ_STATE_OPENREQ:
		if (v) {
1599 1600
			struct inet_connection_sock *icsk = inet_csk(st->syn_wait_sk);
			read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
L
Linus Torvalds 已提交
1601 1602 1603
		}
	case TCP_SEQ_STATE_LISTENING:
		if (v != SEQ_START_TOKEN)
1604
			inet_listen_unlock(&tcp_hashinfo);
L
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1605 1606 1607 1608
		break;
	case TCP_SEQ_STATE_TIME_WAIT:
	case TCP_SEQ_STATE_ESTABLISHED:
		if (v)
1609
			read_unlock(&tcp_hashinfo.ehash[st->bucket].lock);
L
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1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675
		local_bh_enable();
		break;
	}
}

static int tcp_seq_open(struct inode *inode, struct file *file)
{
	struct tcp_seq_afinfo *afinfo = PDE(inode)->data;
	struct seq_file *seq;
	struct tcp_iter_state *s;
	int rc;

	if (unlikely(afinfo == NULL))
		return -EINVAL;

	s = kmalloc(sizeof(*s), GFP_KERNEL);
	if (!s)
		return -ENOMEM;
	memset(s, 0, sizeof(*s));
	s->family		= afinfo->family;
	s->seq_ops.start	= tcp_seq_start;
	s->seq_ops.next		= tcp_seq_next;
	s->seq_ops.show		= afinfo->seq_show;
	s->seq_ops.stop		= tcp_seq_stop;

	rc = seq_open(file, &s->seq_ops);
	if (rc)
		goto out_kfree;
	seq	     = file->private_data;
	seq->private = s;
out:
	return rc;
out_kfree:
	kfree(s);
	goto out;
}

int tcp_proc_register(struct tcp_seq_afinfo *afinfo)
{
	int rc = 0;
	struct proc_dir_entry *p;

	if (!afinfo)
		return -EINVAL;
	afinfo->seq_fops->owner		= afinfo->owner;
	afinfo->seq_fops->open		= tcp_seq_open;
	afinfo->seq_fops->read		= seq_read;
	afinfo->seq_fops->llseek	= seq_lseek;
	afinfo->seq_fops->release	= seq_release_private;
	
	p = proc_net_fops_create(afinfo->name, S_IRUGO, afinfo->seq_fops);
	if (p)
		p->data = afinfo;
	else
		rc = -ENOMEM;
	return rc;
}

void tcp_proc_unregister(struct tcp_seq_afinfo *afinfo)
{
	if (!afinfo)
		return;
	proc_net_remove(afinfo->name);
	memset(afinfo->seq_fops, 0, sizeof(*afinfo->seq_fops)); 
}

1676
static void get_openreq4(struct sock *sk, struct request_sock *req,
L
Linus Torvalds 已提交
1677 1678
			 char *tmpbuf, int i, int uid)
{
1679
	const struct inet_request_sock *ireq = inet_rsk(req);
L
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1680 1681 1682 1683 1684
	int ttd = req->expires - jiffies;

	sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X"
		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %p",
		i,
1685
		ireq->loc_addr,
L
Linus Torvalds 已提交
1686
		ntohs(inet_sk(sk)->sport),
1687 1688
		ireq->rmt_addr,
		ntohs(ireq->rmt_port),
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		TCP_SYN_RECV,
		0, 0, /* could print option size, but that is af dependent. */
		1,    /* timers active (only the expire timer) */
		jiffies_to_clock_t(ttd),
		req->retrans,
		uid,
		0,  /* non standard timer */
		0, /* open_requests have no inode */
		atomic_read(&sk->sk_refcnt),
		req);
}

static void get_tcp4_sock(struct sock *sp, char *tmpbuf, int i)
{
	int timer_active;
	unsigned long timer_expires;
	struct tcp_sock *tp = tcp_sk(sp);
1706
	const struct inet_connection_sock *icsk = inet_csk(sp);
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	struct inet_sock *inet = inet_sk(sp);
	unsigned int dest = inet->daddr;
	unsigned int src = inet->rcv_saddr;
	__u16 destp = ntohs(inet->dport);
	__u16 srcp = ntohs(inet->sport);

1713
	if (icsk->icsk_pending == ICSK_TIME_RETRANS) {
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		timer_active	= 1;
1715 1716
		timer_expires	= icsk->icsk_timeout;
	} else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
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		timer_active	= 4;
1718
		timer_expires	= icsk->icsk_timeout;
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	} else if (timer_pending(&sp->sk_timer)) {
		timer_active	= 2;
		timer_expires	= sp->sk_timer.expires;
	} else {
		timer_active	= 0;
		timer_expires = jiffies;
	}

	sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
			"%08X %5d %8d %lu %d %p %u %u %u %u %d",
		i, src, srcp, dest, destp, sp->sk_state,
1730 1731
		tp->write_seq - tp->snd_una,
		(sp->sk_state == TCP_LISTEN) ? sp->sk_ack_backlog : (tp->rcv_nxt - tp->copied_seq),
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		timer_active,
		jiffies_to_clock_t(timer_expires - jiffies),
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		icsk->icsk_retransmits,
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		sock_i_uid(sp),
1736
		icsk->icsk_probes_out,
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		sock_i_ino(sp),
		atomic_read(&sp->sk_refcnt), sp,
1739 1740 1741
		icsk->icsk_rto,
		icsk->icsk_ack.ato,
		(icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
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		tp->snd_cwnd,
		tp->snd_ssthresh >= 0xFFFF ? -1 : tp->snd_ssthresh);
}

1746
static void get_timewait4_sock(struct inet_timewait_sock *tw, char *tmpbuf, int i)
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{
	unsigned int dest, src;
	__u16 destp, srcp;
	int ttd = tw->tw_ttd - jiffies;

	if (ttd < 0)
		ttd = 0;

	dest  = tw->tw_daddr;
	src   = tw->tw_rcv_saddr;
	destp = ntohs(tw->tw_dport);
	srcp  = ntohs(tw->tw_sport);

	sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X"
		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %p",
		i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
		3, jiffies_to_clock_t(ttd), 0, 0, 0, 0,
		atomic_read(&tw->tw_refcnt), tw);
}

#define TMPSZ 150

static int tcp4_seq_show(struct seq_file *seq, void *v)
{
	struct tcp_iter_state* st;
	char tmpbuf[TMPSZ + 1];

	if (v == SEQ_START_TOKEN) {
		seq_printf(seq, "%-*s\n", TMPSZ - 1,
			   "  sl  local_address rem_address   st tx_queue "
			   "rx_queue tr tm->when retrnsmt   uid  timeout "
			   "inode");
		goto out;
	}
	st = seq->private;

	switch (st->state) {
	case TCP_SEQ_STATE_LISTENING:
	case TCP_SEQ_STATE_ESTABLISHED:
		get_tcp4_sock(v, tmpbuf, st->num);
		break;
	case TCP_SEQ_STATE_OPENREQ:
		get_openreq4(st->syn_wait_sk, v, tmpbuf, st->num, st->uid);
		break;
	case TCP_SEQ_STATE_TIME_WAIT:
		get_timewait4_sock(v, tmpbuf, st->num);
		break;
	}
	seq_printf(seq, "%-*s\n", TMPSZ - 1, tmpbuf);
out:
	return 0;
}

static struct file_operations tcp4_seq_fops;
static struct tcp_seq_afinfo tcp4_seq_afinfo = {
	.owner		= THIS_MODULE,
	.name		= "tcp",
	.family		= AF_INET,
	.seq_show	= tcp4_seq_show,
	.seq_fops	= &tcp4_seq_fops,
};

int __init tcp4_proc_init(void)
{
	return tcp_proc_register(&tcp4_seq_afinfo);
}

void tcp4_proc_exit(void)
{
	tcp_proc_unregister(&tcp4_seq_afinfo);
}
#endif /* CONFIG_PROC_FS */

struct proto tcp_prot = {
	.name			= "TCP",
	.owner			= THIS_MODULE,
	.close			= tcp_close,
	.connect		= tcp_v4_connect,
	.disconnect		= tcp_disconnect,
1826
	.accept			= inet_csk_accept,
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	.ioctl			= tcp_ioctl,
	.init			= tcp_v4_init_sock,
	.destroy		= tcp_v4_destroy_sock,
	.shutdown		= tcp_shutdown,
	.setsockopt		= tcp_setsockopt,
	.getsockopt		= tcp_getsockopt,
	.sendmsg		= tcp_sendmsg,
	.recvmsg		= tcp_recvmsg,
	.backlog_rcv		= tcp_v4_do_rcv,
	.hash			= tcp_v4_hash,
	.unhash			= tcp_unhash,
	.get_port		= tcp_v4_get_port,
	.enter_memory_pressure	= tcp_enter_memory_pressure,
	.sockets_allocated	= &tcp_sockets_allocated,
1841
	.orphan_count		= &tcp_orphan_count,
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	.memory_allocated	= &tcp_memory_allocated,
	.memory_pressure	= &tcp_memory_pressure,
	.sysctl_mem		= sysctl_tcp_mem,
	.sysctl_wmem		= sysctl_tcp_wmem,
	.sysctl_rmem		= sysctl_tcp_rmem,
	.max_header		= MAX_TCP_HEADER,
	.obj_size		= sizeof(struct tcp_sock),
1849
	.twsk_prot		= &tcp_timewait_sock_ops,
1850
	.rsk_prot		= &tcp_request_sock_ops,
1851 1852 1853 1854
#ifdef CONFIG_COMPAT
	.compat_setsockopt	= compat_tcp_setsockopt,
	.compat_getsockopt	= compat_tcp_getsockopt,
#endif
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};

void __init tcp_v4_init(struct net_proto_family *ops)
{
1859
	if (inet_csk_ctl_sock_create(&tcp_socket, PF_INET, SOCK_RAW, IPPROTO_TCP) < 0)
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		panic("Failed to create the TCP control socket.\n");
}

EXPORT_SYMBOL(ipv4_specific);
EXPORT_SYMBOL(tcp_hashinfo);
EXPORT_SYMBOL(tcp_prot);
EXPORT_SYMBOL(tcp_unhash);
EXPORT_SYMBOL(tcp_v4_conn_request);
EXPORT_SYMBOL(tcp_v4_connect);
EXPORT_SYMBOL(tcp_v4_do_rcv);
EXPORT_SYMBOL(tcp_v4_remember_stamp);
EXPORT_SYMBOL(tcp_v4_send_check);
EXPORT_SYMBOL(tcp_v4_syn_recv_sock);

#ifdef CONFIG_PROC_FS
EXPORT_SYMBOL(tcp_proc_register);
EXPORT_SYMBOL(tcp_proc_unregister);
#endif
EXPORT_SYMBOL(sysctl_local_port_range);
EXPORT_SYMBOL(sysctl_tcp_low_latency);