tcp_ipv4.c 61.1 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>

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#include <linux/crypto.h>
#include <linux/scatterlist.h>

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int sysctl_tcp_tw_reuse __read_mostly;
int sysctl_tcp_low_latency __read_mostly;
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/* Check TCP sequence numbers in ICMP packets. */
#define ICMP_MIN_LENGTH 8

/* Socket used for sending RSTs */
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static struct socket *tcp_socket __read_mostly;
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void tcp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb);
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#ifdef CONFIG_TCP_MD5SIG
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static struct tcp_md5sig_key *tcp_v4_md5_do_lookup(struct sock *sk,
						   __be32 addr);
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static int tcp_v4_do_calc_md5_hash(char *md5_hash, struct tcp_md5sig_key *key,
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				   __be32 saddr, __be32 daddr,
				   struct tcphdr *th, int protocol,
				   int tcplen);
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#endif

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struct inet_hashinfo __cacheline_aligned tcp_hashinfo = {
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	.lhash_lock  = __RW_LOCK_UNLOCKED(tcp_hashinfo.lhash_lock),
	.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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}

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static inline __u32 tcp_v4_init_sequence(struct sk_buff *skb)
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{
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	return secure_tcp_sequence_number(ip_hdr(skb)->daddr,
					  ip_hdr(skb)->saddr,
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					  tcp_hdr(skb)->dest,
					  tcp_hdr(skb)->source);
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}

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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 &&
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			     get_seconds() - tcptw->tw_ts_recent_stamp > 1))) {
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		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;
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	__be32 daddr, nexthop;
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	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,
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			       inet->sport, usin->sin_port, sk, 1);
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	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);
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		/*
		 * 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.
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		 */
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		if (peer != NULL &&
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		    peer->tcp_ts_stamp + TCP_PAWS_MSL >= get_seconds()) {
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			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:
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	/*
	 * This unhashes the socket and releases the local port,
	 * if necessary.
	 */
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	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.
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	 * There is a small race when the user changes this flag in the
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	 * 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;
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	const int type = icmp_hdr(skb)->type;
	const int code = icmp_hdr(skb)->code;
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	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(inet_twsk(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)) {
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		NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
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		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)) {
			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 = tcp_hdr(skb);
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	if (skb->ip_summed == CHECKSUM_PARTIAL) {
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		th->check = ~tcp_v4_check(len, inet->saddr,
					  inet->daddr, 0);
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		skb->csum_start = skb_transport_header(skb) - skb->head;
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		skb->csum_offset = offsetof(struct tcphdr, check);
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	} else {
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		th->check = tcp_v4_check(len, inet->saddr, inet->daddr,
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					 csum_partial((char *)th,
						      th->doff << 2,
						      skb->csum));
	}
}

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int tcp_v4_gso_send_check(struct sk_buff *skb)
{
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	const struct iphdr *iph;
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	struct tcphdr *th;

	if (!pskb_may_pull(skb, sizeof(*th)))
		return -EINVAL;

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	iph = ip_hdr(skb);
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	th = tcp_hdr(skb);
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	th->check = 0;
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	th->check = ~tcp_v4_check(skb->len, iph->saddr, iph->daddr, 0);
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	skb->csum_start = skb_transport_header(skb) - skb->head;
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	skb->csum_offset = offsetof(struct tcphdr, check);
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	skb->ip_summed = CHECKSUM_PARTIAL;
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	return 0;
}

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/*
 *	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.
 */

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static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
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{
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	struct tcphdr *th = tcp_hdr(skb);
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	struct {
		struct tcphdr th;
#ifdef CONFIG_TCP_MD5SIG
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		__be32 opt[(TCPOLEN_MD5SIG_ALIGNED >> 2)];
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#endif
	} rep;
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	struct ip_reply_arg arg;
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#ifdef CONFIG_TCP_MD5SIG
	struct tcp_md5sig_key *key;
#endif
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	/* 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. */
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	memset(&rep, 0, sizeof(rep));
	rep.th.dest   = th->source;
	rep.th.source = th->dest;
	rep.th.doff   = sizeof(struct tcphdr) / 4;
	rep.th.rst    = 1;
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	if (th->ack) {
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		rep.th.seq = th->ack_seq;
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	} else {
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		rep.th.ack = 1;
		rep.th.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin +
				       skb->len - (th->doff << 2));
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Linus Torvalds 已提交
583 584
	}

585
	memset(&arg, 0, sizeof(arg));
586 587 588 589
	arg.iov[0].iov_base = (unsigned char *)&rep;
	arg.iov[0].iov_len  = sizeof(rep.th);

#ifdef CONFIG_TCP_MD5SIG
590
	key = sk ? tcp_v4_md5_do_lookup(sk, ip_hdr(skb)->daddr) : NULL;
591 592 593 594 595 596 597 598 599 600 601
	if (key) {
		rep.opt[0] = htonl((TCPOPT_NOP << 24) |
				   (TCPOPT_NOP << 16) |
				   (TCPOPT_MD5SIG << 8) |
				   TCPOLEN_MD5SIG);
		/* Update length and the length the header thinks exists */
		arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
		rep.th.doff = arg.iov[0].iov_len / 4;

		tcp_v4_do_calc_md5_hash((__u8 *)&rep.opt[1],
					key,
602 603
					ip_hdr(skb)->daddr,
					ip_hdr(skb)->saddr,
604 605 606 607
					&rep.th, IPPROTO_TCP,
					arg.iov[0].iov_len);
	}
#endif
608 609
	arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
				      ip_hdr(skb)->saddr, /* XXX */
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610 611 612
				      sizeof(struct tcphdr), IPPROTO_TCP, 0);
	arg.csumoffset = offsetof(struct tcphdr, check) / 2;

613
	ip_send_reply(tcp_socket->sk, skb, &arg, arg.iov[0].iov_len);
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	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?
 */

623 624
static void tcp_v4_send_ack(struct tcp_timewait_sock *twsk,
			    struct sk_buff *skb, u32 seq, u32 ack,
L
Linus Torvalds 已提交
625 626
			    u32 win, u32 ts)
{
627
	struct tcphdr *th = tcp_hdr(skb);
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628 629
	struct {
		struct tcphdr th;
630
		__be32 opt[(TCPOLEN_TSTAMP_ALIGNED >> 2)
631
#ifdef CONFIG_TCP_MD5SIG
632
			   + (TCPOLEN_MD5SIG_ALIGNED >> 2)
633 634
#endif
			];
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635 636
	} rep;
	struct ip_reply_arg arg;
637 638 639 640
#ifdef CONFIG_TCP_MD5SIG
	struct tcp_md5sig_key *key;
	struct tcp_md5sig_key tw_key;
#endif
L
Linus Torvalds 已提交
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	memset(&rep.th, 0, sizeof(struct tcphdr));
643
	memset(&arg, 0, sizeof(arg));
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	arg.iov[0].iov_base = (unsigned char *)&rep;
	arg.iov[0].iov_len  = sizeof(rep.th);
	if (ts) {
648 649 650 651 652
		rep.opt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
				   (TCPOPT_TIMESTAMP << 8) |
				   TCPOLEN_TIMESTAMP);
		rep.opt[1] = htonl(tcp_time_stamp);
		rep.opt[2] = htonl(ts);
653
		arg.iov[0].iov_len += TCPOLEN_TSTAMP_ALIGNED;
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	}

	/* 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);

665 666 667 668 669 670 671 672 673 674
#ifdef CONFIG_TCP_MD5SIG
	/*
	 * The SKB holds an imcoming packet, but may not have a valid ->sk
	 * pointer. This is especially the case when we're dealing with a
	 * TIME_WAIT ack, because the sk structure is long gone, and only
	 * the tcp_timewait_sock remains. So the md5 key is stashed in that
	 * structure, and we use it in preference.  I believe that (twsk ||
	 * skb->sk) holds true, but we program defensively.
	 */
	if (!twsk && skb->sk) {
675
		key = tcp_v4_md5_do_lookup(skb->sk, ip_hdr(skb)->daddr);
676 677 678 679
	} else if (twsk && twsk->tw_md5_keylen) {
		tw_key.key = twsk->tw_md5_key;
		tw_key.keylen = twsk->tw_md5_keylen;
		key = &tw_key;
680
	} else
681 682 683 684 685 686 687 688 689 690 691 692 693 694
		key = NULL;

	if (key) {
		int offset = (ts) ? 3 : 0;

		rep.opt[offset++] = htonl((TCPOPT_NOP << 24) |
					  (TCPOPT_NOP << 16) |
					  (TCPOPT_MD5SIG << 8) |
					  TCPOLEN_MD5SIG);
		arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
		rep.th.doff = arg.iov[0].iov_len/4;

		tcp_v4_do_calc_md5_hash((__u8 *)&rep.opt[offset],
					key,
695 696
					ip_hdr(skb)->daddr,
					ip_hdr(skb)->saddr,
697 698 699 700
					&rep.th, IPPROTO_TCP,
					arg.iov[0].iov_len);
	}
#endif
701 702
	arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
				      ip_hdr(skb)->saddr, /* XXX */
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				      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)
{
713
	struct inet_timewait_sock *tw = inet_twsk(sk);
714
	struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
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716
	tcp_v4_send_ack(tcptw, skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
717 718
			tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
			tcptw->tw_ts_recent);
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Linus Torvalds 已提交
719

720
	inet_twsk_put(tw);
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}

723 724
static void tcp_v4_reqsk_send_ack(struct sk_buff *skb,
				  struct request_sock *req)
L
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725
{
726 727
	tcp_v4_send_ack(NULL, skb, tcp_rsk(req)->snt_isn + 1,
			tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd,
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			req->ts_recent);
}

/*
 *	Send a SYN-ACK after having received an ACK.
733
 *	This still operates on a request_sock only, not on a big
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734 735
 *	socket.
 */
736
static int tcp_v4_send_synack(struct sock *sk, struct request_sock *req,
L
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737 738
			      struct dst_entry *dst)
{
739
	const struct inet_request_sock *ireq = inet_rsk(req);
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740 741 742 743
	int err = -1;
	struct sk_buff * skb;

	/* First, grab a route. */
744
	if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
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		goto out;

	skb = tcp_make_synack(sk, dst, req);

	if (skb) {
750
		struct tcphdr *th = tcp_hdr(skb);
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751

752
		th->check = tcp_v4_check(skb->len,
753 754
					 ireq->loc_addr,
					 ireq->rmt_addr,
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755 756 757
					 csum_partial((char *)th, skb->len,
						      skb->csum));

758 759 760
		err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
					    ireq->rmt_addr,
					    ireq->opt);
761
		err = net_xmit_eval(err);
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762 763 764 765 766 767 768 769
	}

out:
	dst_release(dst);
	return err;
}

/*
770
 *	IPv4 request_sock destructor.
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Linus Torvalds 已提交
771
 */
772
static void tcp_v4_reqsk_destructor(struct request_sock *req)
L
Linus Torvalds 已提交
773
{
J
Jesper Juhl 已提交
774
	kfree(inet_rsk(req)->opt);
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775 776
}

777
#ifdef CONFIG_SYN_COOKIES
S
Stephen Hemminger 已提交
778
static void syn_flood_warning(struct sk_buff *skb)
L
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779 780 781 782 783 784 785
{
	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",
786
		       ntohs(tcp_hdr(skb)->dest));
L
Linus Torvalds 已提交
787 788
	}
}
789
#endif
L
Linus Torvalds 已提交
790 791

/*
792
 * Save and compile IPv4 options into the request_sock if needed.
L
Linus Torvalds 已提交
793
 */
S
Stephen Hemminger 已提交
794 795
static struct ip_options *tcp_v4_save_options(struct sock *sk,
					      struct sk_buff *skb)
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{
	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;
}

813 814 815 816 817 818 819 820
#ifdef CONFIG_TCP_MD5SIG
/*
 * RFC2385 MD5 checksumming requires a mapping of
 * IP address->MD5 Key.
 * We need to maintain these in the sk structure.
 */

/* Find the Key structure for an address.  */
821 822
static struct tcp_md5sig_key *
			tcp_v4_md5_do_lookup(struct sock *sk, __be32 addr)
823 824 825 826 827 828 829 830
{
	struct tcp_sock *tp = tcp_sk(sk);
	int i;

	if (!tp->md5sig_info || !tp->md5sig_info->entries4)
		return NULL;
	for (i = 0; i < tp->md5sig_info->entries4; i++) {
		if (tp->md5sig_info->keys4[i].addr == addr)
831 832
			return (struct tcp_md5sig_key *)
						&tp->md5sig_info->keys4[i];
833 834 835 836 837 838 839 840 841 842 843 844
	}
	return NULL;
}

struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
					 struct sock *addr_sk)
{
	return tcp_v4_md5_do_lookup(sk, inet_sk(addr_sk)->daddr);
}

EXPORT_SYMBOL(tcp_v4_md5_lookup);

A
Adrian Bunk 已提交
845 846
static struct tcp_md5sig_key *tcp_v4_reqsk_md5_lookup(struct sock *sk,
						      struct request_sock *req)
847 848 849 850 851 852 853 854 855 856 857 858 859
{
	return tcp_v4_md5_do_lookup(sk, inet_rsk(req)->rmt_addr);
}

/* This can be called on a newly created socket, from other files */
int tcp_v4_md5_do_add(struct sock *sk, __be32 addr,
		      u8 *newkey, u8 newkeylen)
{
	/* Add Key to the list */
	struct tcp4_md5sig_key *key;
	struct tcp_sock *tp = tcp_sk(sk);
	struct tcp4_md5sig_key *keys;

860
	key = (struct tcp4_md5sig_key *)tcp_v4_md5_do_lookup(sk, addr);
861 862
	if (key) {
		/* Pre-existing entry - just update that one. */
863
		kfree(key->key);
864 865 866
		key->key = newkey;
		key->keylen = newkeylen;
	} else {
867 868
		struct tcp_md5sig_info *md5sig;

869
		if (!tp->md5sig_info) {
870 871
			tp->md5sig_info = kzalloc(sizeof(*tp->md5sig_info),
						  GFP_ATOMIC);
872 873 874 875 876 877 878 879 880
			if (!tp->md5sig_info) {
				kfree(newkey);
				return -ENOMEM;
			}
		}
		if (tcp_alloc_md5sig_pool() == NULL) {
			kfree(newkey);
			return -ENOMEM;
		}
881 882 883 884
		md5sig = tp->md5sig_info;

		if (md5sig->alloced4 == md5sig->entries4) {
			keys = kmalloc((sizeof(*keys) *
885
					(md5sig->entries4 + 1)), GFP_ATOMIC);
886 887 888 889 890 891
			if (!keys) {
				kfree(newkey);
				tcp_free_md5sig_pool();
				return -ENOMEM;
			}

892 893 894
			if (md5sig->entries4)
				memcpy(keys, md5sig->keys4,
				       sizeof(*keys) * md5sig->entries4);
895 896

			/* Free old key list, and reference new one */
897 898 899 900
			if (md5sig->keys4)
				kfree(md5sig->keys4);
			md5sig->keys4 = keys;
			md5sig->alloced4++;
901
		}
902 903 904 905
		md5sig->entries4++;
		md5sig->keys4[md5sig->entries4 - 1].addr   = addr;
		md5sig->keys4[md5sig->entries4 - 1].key    = newkey;
		md5sig->keys4[md5sig->entries4 - 1].keylen = newkeylen;
906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932
	}
	return 0;
}

EXPORT_SYMBOL(tcp_v4_md5_do_add);

static int tcp_v4_md5_add_func(struct sock *sk, struct sock *addr_sk,
			       u8 *newkey, u8 newkeylen)
{
	return tcp_v4_md5_do_add(sk, inet_sk(addr_sk)->daddr,
				 newkey, newkeylen);
}

int tcp_v4_md5_do_del(struct sock *sk, __be32 addr)
{
	struct tcp_sock *tp = tcp_sk(sk);
	int i;

	for (i = 0; i < tp->md5sig_info->entries4; i++) {
		if (tp->md5sig_info->keys4[i].addr == addr) {
			/* Free the key */
			kfree(tp->md5sig_info->keys4[i].key);
			tp->md5sig_info->entries4--;

			if (tp->md5sig_info->entries4 == 0) {
				kfree(tp->md5sig_info->keys4);
				tp->md5sig_info->keys4 = NULL;
933
				tp->md5sig_info->alloced4 = 0;
934
			} else if (tp->md5sig_info->entries4 != i) {
935
				/* Need to do some manipulation */
936 937 938
				memcpy(&tp->md5sig_info->keys4[i],
				       &tp->md5sig_info->keys4[i+1],
				       (tp->md5sig_info->entries4 - i) *
939
					sizeof(struct tcp4_md5sig_key));
940 941 942 943 944 945 946 947 948 949
			}
			tcp_free_md5sig_pool();
			return 0;
		}
	}
	return -ENOENT;
}

EXPORT_SYMBOL(tcp_v4_md5_do_del);

950
static void tcp_v4_clear_md5_list(struct sock *sk)
951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971
{
	struct tcp_sock *tp = tcp_sk(sk);

	/* Free each key, then the set of key keys,
	 * the crypto element, and then decrement our
	 * hold on the last resort crypto.
	 */
	if (tp->md5sig_info->entries4) {
		int i;
		for (i = 0; i < tp->md5sig_info->entries4; i++)
			kfree(tp->md5sig_info->keys4[i].key);
		tp->md5sig_info->entries4 = 0;
		tcp_free_md5sig_pool();
	}
	if (tp->md5sig_info->keys4) {
		kfree(tp->md5sig_info->keys4);
		tp->md5sig_info->keys4 = NULL;
		tp->md5sig_info->alloced4  = 0;
	}
}

972 973
static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval,
				 int optlen)
974 975 976 977 978 979 980 981
{
	struct tcp_md5sig cmd;
	struct sockaddr_in *sin = (struct sockaddr_in *)&cmd.tcpm_addr;
	u8 *newkey;

	if (optlen < sizeof(cmd))
		return -EINVAL;

982
	if (copy_from_user(&cmd, optval, sizeof(cmd)))
983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998
		return -EFAULT;

	if (sin->sin_family != AF_INET)
		return -EINVAL;

	if (!cmd.tcpm_key || !cmd.tcpm_keylen) {
		if (!tcp_sk(sk)->md5sig_info)
			return -ENOENT;
		return tcp_v4_md5_do_del(sk, sin->sin_addr.s_addr);
	}

	if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
		return -EINVAL;

	if (!tcp_sk(sk)->md5sig_info) {
		struct tcp_sock *tp = tcp_sk(sk);
999
		struct tcp_md5sig_info *p = kzalloc(sizeof(*p), GFP_KERNEL);
1000 1001 1002 1003 1004 1005 1006 1007

		if (!p)
			return -EINVAL;

		tp->md5sig_info = p;

	}

1008
	newkey = kmemdup(cmd.tcpm_key, cmd.tcpm_keylen, GFP_KERNEL);
1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022
	if (!newkey)
		return -ENOMEM;
	return tcp_v4_md5_do_add(sk, sin->sin_addr.s_addr,
				 newkey, cmd.tcpm_keylen);
}

static int tcp_v4_do_calc_md5_hash(char *md5_hash, struct tcp_md5sig_key *key,
				   __be32 saddr, __be32 daddr,
				   struct tcphdr *th, int protocol,
				   int tcplen)
{
	struct scatterlist sg[4];
	__u16 data_len;
	int block = 0;
1023
	__sum16 old_checksum;
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 1058 1059 1060 1061
	struct tcp_md5sig_pool *hp;
	struct tcp4_pseudohdr *bp;
	struct hash_desc *desc;
	int err;
	unsigned int nbytes = 0;

	/*
	 * Okay, so RFC2385 is turned on for this connection,
	 * so we need to generate the MD5 hash for the packet now.
	 */

	hp = tcp_get_md5sig_pool();
	if (!hp)
		goto clear_hash_noput;

	bp = &hp->md5_blk.ip4;
	desc = &hp->md5_desc;

	/*
	 * 1. the TCP pseudo-header (in the order: source IP address,
	 * destination IP address, zero-padded protocol number, and
	 * segment length)
	 */
	bp->saddr = saddr;
	bp->daddr = daddr;
	bp->pad = 0;
	bp->protocol = protocol;
	bp->len = htons(tcplen);
	sg_set_buf(&sg[block++], bp, sizeof(*bp));
	nbytes += sizeof(*bp);

	/* 2. the TCP header, excluding options, and assuming a
	 * checksum of zero/
	 */
	old_checksum = th->check;
	th->check = 0;
	sg_set_buf(&sg[block++], th, sizeof(struct tcphdr));
	nbytes += sizeof(struct tcphdr);
1062

1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125
	/* 3. the TCP segment data (if any) */
	data_len = tcplen - (th->doff << 2);
	if (data_len > 0) {
		unsigned char *data = (unsigned char *)th + (th->doff << 2);
		sg_set_buf(&sg[block++], data, data_len);
		nbytes += data_len;
	}

	/* 4. an independently-specified key or password, known to both
	 * TCPs and presumably connection-specific
	 */
	sg_set_buf(&sg[block++], key->key, key->keylen);
	nbytes += key->keylen;

	/* Now store the Hash into the packet */
	err = crypto_hash_init(desc);
	if (err)
		goto clear_hash;
	err = crypto_hash_update(desc, sg, nbytes);
	if (err)
		goto clear_hash;
	err = crypto_hash_final(desc, md5_hash);
	if (err)
		goto clear_hash;

	/* Reset header, and free up the crypto */
	tcp_put_md5sig_pool();
	th->check = old_checksum;

out:
	return 0;
clear_hash:
	tcp_put_md5sig_pool();
clear_hash_noput:
	memset(md5_hash, 0, 16);
	goto out;
}

int tcp_v4_calc_md5_hash(char *md5_hash, struct tcp_md5sig_key *key,
			 struct sock *sk,
			 struct dst_entry *dst,
			 struct request_sock *req,
			 struct tcphdr *th, int protocol,
			 int tcplen)
{
	__be32 saddr, daddr;

	if (sk) {
		saddr = inet_sk(sk)->saddr;
		daddr = inet_sk(sk)->daddr;
	} else {
		struct rtable *rt = (struct rtable *)dst;
		BUG_ON(!rt);
		saddr = rt->rt_src;
		daddr = rt->rt_dst;
	}
	return tcp_v4_do_calc_md5_hash(md5_hash, key,
				       saddr, daddr,
				       th, protocol, tcplen);
}

EXPORT_SYMBOL(tcp_v4_calc_md5_hash);

1126
static int tcp_v4_inbound_md5_hash(struct sock *sk, struct sk_buff *skb)
1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137
{
	/*
	 * This gets called for each TCP segment that arrives
	 * so we want to be efficient.
	 * We have 3 drop cases:
	 * o No MD5 hash and one expected.
	 * o MD5 hash and we're not expecting one.
	 * o MD5 hash and its wrong.
	 */
	__u8 *hash_location = NULL;
	struct tcp_md5sig_key *hash_expected;
1138
	const struct iphdr *iph = ip_hdr(skb);
1139
	struct tcphdr *th = tcp_hdr(skb);
1140
	int length = (th->doff << 2) - sizeof(struct tcphdr);
1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190
	int genhash;
	unsigned char *ptr;
	unsigned char newhash[16];

	hash_expected = tcp_v4_md5_do_lookup(sk, iph->saddr);

	/*
	 * If the TCP option length is less than the TCP_MD5SIG
	 * option length, then we can shortcut
	 */
	if (length < TCPOLEN_MD5SIG) {
		if (hash_expected)
			return 1;
		else
			return 0;
	}

	/* Okay, we can't shortcut - we have to grub through the options */
	ptr = (unsigned char *)(th + 1);
	while (length > 0) {
		int opcode = *ptr++;
		int opsize;

		switch (opcode) {
		case TCPOPT_EOL:
			goto done_opts;
		case TCPOPT_NOP:
			length--;
			continue;
		default:
			opsize = *ptr++;
			if (opsize < 2)
				goto done_opts;
			if (opsize > length)
				goto done_opts;

			if (opcode == TCPOPT_MD5SIG) {
				hash_location = ptr;
				goto done_opts;
			}
		}
		ptr += opsize-2;
		length -= opsize;
	}
done_opts:
	/* We've parsed the options - do we have a hash? */
	if (!hash_expected && !hash_location)
		return 0;

	if (hash_expected && !hash_location) {
1191
		LIMIT_NETDEBUG(KERN_INFO "MD5 Hash expected but NOT found "
1192
			       "(" NIPQUAD_FMT ", %d)->(" NIPQUAD_FMT ", %d)\n",
1193 1194
			       NIPQUAD(iph->saddr), ntohs(th->source),
			       NIPQUAD(iph->daddr), ntohs(th->dest));
1195 1196 1197 1198
		return 1;
	}

	if (!hash_expected && hash_location) {
1199
		LIMIT_NETDEBUG(KERN_INFO "MD5 Hash NOT expected but found "
1200
			       "(" NIPQUAD_FMT ", %d)->(" NIPQUAD_FMT ", %d)\n",
1201 1202
			       NIPQUAD(iph->saddr), ntohs(th->source),
			       NIPQUAD(iph->daddr), ntohs(th->dest));
1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218
		return 1;
	}

	/* Okay, so this is hash_expected and hash_location -
	 * so we need to calculate the checksum.
	 */
	genhash = tcp_v4_do_calc_md5_hash(newhash,
					  hash_expected,
					  iph->saddr, iph->daddr,
					  th, sk->sk_protocol,
					  skb->len);

	if (genhash || memcmp(hash_location, newhash, 16) != 0) {
		if (net_ratelimit()) {
			printk(KERN_INFO "MD5 Hash failed for "
			       "(" NIPQUAD_FMT ", %d)->(" NIPQUAD_FMT ", %d)%s\n",
1219 1220
			       NIPQUAD(iph->saddr), ntohs(th->source),
			       NIPQUAD(iph->daddr), ntohs(th->dest),
1221 1222 1223 1224 1225 1226 1227 1228 1229
			       genhash ? " tcp_v4_calc_md5_hash failed" : "");
		}
		return 1;
	}
	return 0;
}

#endif

1230
struct request_sock_ops tcp_request_sock_ops __read_mostly = {
L
Linus Torvalds 已提交
1231
	.family		=	PF_INET,
1232
	.obj_size	=	sizeof(struct tcp_request_sock),
L
Linus Torvalds 已提交
1233
	.rtx_syn_ack	=	tcp_v4_send_synack,
1234 1235
	.send_ack	=	tcp_v4_reqsk_send_ack,
	.destructor	=	tcp_v4_reqsk_destructor,
L
Linus Torvalds 已提交
1236 1237 1238
	.send_reset	=	tcp_v4_send_reset,
};

1239
#ifdef CONFIG_TCP_MD5SIG
1240
static struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
1241 1242
	.md5_lookup	=	tcp_v4_reqsk_md5_lookup,
};
1243
#endif
1244

1245 1246 1247
static struct timewait_sock_ops tcp_timewait_sock_ops = {
	.twsk_obj_size	= sizeof(struct tcp_timewait_sock),
	.twsk_unique	= tcp_twsk_unique,
1248
	.twsk_destructor= tcp_twsk_destructor,
1249 1250
};

L
Linus Torvalds 已提交
1251 1252
int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
{
1253
	struct inet_request_sock *ireq;
L
Linus Torvalds 已提交
1254
	struct tcp_options_received tmp_opt;
1255
	struct request_sock *req;
1256 1257
	__be32 saddr = ip_hdr(skb)->saddr;
	__be32 daddr = ip_hdr(skb)->daddr;
L
Linus Torvalds 已提交
1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274
	__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.
	 */
1275
	if (inet_csk_reqsk_queue_is_full(sk) && !isn) {
L
Linus Torvalds 已提交
1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288
#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.
	 */
1289
	if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
L
Linus Torvalds 已提交
1290 1291
		goto drop;

1292
	req = reqsk_alloc(&tcp_request_sock_ops);
L
Linus Torvalds 已提交
1293 1294 1295
	if (!req)
		goto drop;

1296 1297 1298 1299
#ifdef CONFIG_TCP_MD5SIG
	tcp_rsk(req)->af_specific = &tcp_request_sock_ipv4_ops;
#endif

L
Linus Torvalds 已提交
1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323
	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);

1324 1325 1326
	if (security_inet_conn_request(sk, skb, req))
		goto drop_and_free;

1327 1328 1329 1330
	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
1331
	if (!want_cookie)
1332
		TCP_ECN_create_request(req, tcp_hdr(skb));
L
Linus Torvalds 已提交
1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351

	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 &&
1352
		    tcp_death_row.sysctl_tw_recycle &&
1353
		    (dst = inet_csk_route_req(sk, req)) != NULL &&
L
Linus Torvalds 已提交
1354 1355
		    (peer = rt_get_peer((struct rtable *)dst)) != NULL &&
		    peer->v4daddr == saddr) {
1356
			if (get_seconds() < peer->tcp_ts_stamp + TCP_PAWS_MSL &&
L
Linus Torvalds 已提交
1357 1358 1359 1360 1361 1362 1363 1364 1365
			    (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 &&
1366
			 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
L
Linus Torvalds 已提交
1367 1368 1369 1370 1371 1372 1373 1374 1375 1376
			  (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.
			 */
1377 1378 1379
			LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open "
				       "request from %u.%u.%u.%u/%u\n",
				       NIPQUAD(saddr),
1380
				       ntohs(tcp_hdr(skb)->source));
L
Linus Torvalds 已提交
1381 1382 1383 1384
			dst_release(dst);
			goto drop_and_free;
		}

1385
		isn = tcp_v4_init_sequence(skb);
L
Linus Torvalds 已提交
1386
	}
1387
	tcp_rsk(req)->snt_isn = isn;
L
Linus Torvalds 已提交
1388 1389 1390 1391 1392

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

	if (want_cookie) {
1393
		reqsk_free(req);
L
Linus Torvalds 已提交
1394
	} else {
1395
		inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
L
Linus Torvalds 已提交
1396 1397 1398 1399
	}
	return 0;

drop_and_free:
1400
	reqsk_free(req);
L
Linus Torvalds 已提交
1401 1402 1403 1404 1405 1406 1407 1408 1409 1410
drop:
	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,
1411
				  struct request_sock *req,
L
Linus Torvalds 已提交
1412 1413
				  struct dst_entry *dst)
{
1414
	struct inet_request_sock *ireq;
L
Linus Torvalds 已提交
1415 1416 1417
	struct inet_sock *newinet;
	struct tcp_sock *newtp;
	struct sock *newsk;
1418 1419 1420
#ifdef CONFIG_TCP_MD5SIG
	struct tcp_md5sig_key *key;
#endif
L
Linus Torvalds 已提交
1421 1422 1423 1424

	if (sk_acceptq_is_full(sk))
		goto exit_overflow;

1425
	if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
L
Linus Torvalds 已提交
1426 1427 1428 1429 1430 1431
		goto exit;

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

1432
	newsk->sk_gso_type = SKB_GSO_TCPV4;
1433
	sk_setup_caps(newsk, dst);
L
Linus Torvalds 已提交
1434 1435 1436

	newtp		      = tcp_sk(newsk);
	newinet		      = inet_sk(newsk);
1437 1438 1439 1440 1441 1442
	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;
1443
	newinet->mc_index     = inet_iif(skb);
1444
	newinet->mc_ttl	      = ip_hdr(skb)->ttl;
1445
	inet_csk(newsk)->icsk_ext_hdr_len = 0;
L
Linus Torvalds 已提交
1446
	if (newinet->opt)
1447
		inet_csk(newsk)->icsk_ext_hdr_len = newinet->opt->optlen;
L
Linus Torvalds 已提交
1448 1449
	newinet->id = newtp->write_seq ^ jiffies;

J
John Heffner 已提交
1450
	tcp_mtup_init(newsk);
L
Linus Torvalds 已提交
1451 1452 1453 1454
	tcp_sync_mss(newsk, dst_mtu(dst));
	newtp->advmss = dst_metric(dst, RTAX_ADVMSS);
	tcp_initialize_rcv_mss(newsk);

1455 1456 1457 1458 1459 1460 1461 1462 1463
#ifdef CONFIG_TCP_MD5SIG
	/* Copy over the MD5 key from the original socket */
	if ((key = tcp_v4_md5_do_lookup(sk, newinet->daddr)) != NULL) {
		/*
		 * We're using one, so create a matching key
		 * on the newsk structure. If we fail to get
		 * memory, then we end up not copying the key
		 * across. Shucks.
		 */
1464 1465
		char *newkey = kmemdup(key->key, key->keylen, GFP_ATOMIC);
		if (newkey != NULL)
1466 1467 1468 1469 1470
			tcp_v4_md5_do_add(newsk, inet_sk(sk)->daddr,
					  newkey, key->keylen);
	}
#endif

1471
	__inet_hash(&tcp_hashinfo, newsk, 0);
1472
	__inet_inherit_port(&tcp_hashinfo, sk, newsk);
L
Linus Torvalds 已提交
1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485

	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)
{
1486
	struct tcphdr *th = tcp_hdr(skb);
1487
	const struct iphdr *iph = ip_hdr(skb);
L
Linus Torvalds 已提交
1488
	struct sock *nsk;
1489
	struct request_sock **prev;
L
Linus Torvalds 已提交
1490
	/* Find possible connection requests. */
1491 1492
	struct request_sock *req = inet_csk_search_req(sk, &prev, th->source,
						       iph->saddr, iph->daddr);
L
Linus Torvalds 已提交
1493 1494 1495
	if (req)
		return tcp_check_req(sk, skb, req, prev);

1496 1497
	nsk = inet_lookup_established(&tcp_hashinfo, iph->saddr, th->source,
				      iph->daddr, th->dest, inet_iif(skb));
L
Linus Torvalds 已提交
1498 1499 1500 1501 1502 1503

	if (nsk) {
		if (nsk->sk_state != TCP_TIME_WAIT) {
			bh_lock_sock(nsk);
			return nsk;
		}
1504
		inet_twsk_put(inet_twsk(nsk));
L
Linus Torvalds 已提交
1505 1506 1507 1508 1509 1510 1511 1512 1513 1514
		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;
}

1515
static __sum16 tcp_v4_checksum_init(struct sk_buff *skb)
L
Linus Torvalds 已提交
1516
{
1517 1518
	const struct iphdr *iph = ip_hdr(skb);

1519
	if (skb->ip_summed == CHECKSUM_COMPLETE) {
1520 1521
		if (!tcp_v4_check(skb->len, iph->saddr,
				  iph->daddr, skb->csum)) {
1522
			skb->ip_summed = CHECKSUM_UNNECESSARY;
L
Linus Torvalds 已提交
1523
			return 0;
1524
		}
L
Linus Torvalds 已提交
1525
	}
1526

1527
	skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
1528 1529
				       skb->len, IPPROTO_TCP, 0);

L
Linus Torvalds 已提交
1530
	if (skb->len <= 76) {
1531
		return __skb_checksum_complete(skb);
L
Linus Torvalds 已提交
1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546
	}
	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)
{
1547 1548 1549 1550 1551 1552 1553 1554
	struct sock *rsk;
#ifdef CONFIG_TCP_MD5SIG
	/*
	 * We really want to reject the packet as early as possible
	 * if:
	 *  o We're expecting an MD5'd packet and this is no MD5 tcp option
	 *  o There is an MD5 option and we're not expecting one
	 */
1555
	if (tcp_v4_inbound_md5_hash(sk, skb))
1556 1557 1558
		goto discard;
#endif

L
Linus Torvalds 已提交
1559 1560
	if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
		TCP_CHECK_TIMER(sk);
1561
		if (tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len)) {
1562
			rsk = sk;
L
Linus Torvalds 已提交
1563
			goto reset;
1564
		}
L
Linus Torvalds 已提交
1565 1566 1567 1568
		TCP_CHECK_TIMER(sk);
		return 0;
	}

1569
	if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb))
L
Linus Torvalds 已提交
1570 1571 1572 1573 1574 1575 1576 1577
		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) {
1578 1579
			if (tcp_child_process(sk, nsk, skb)) {
				rsk = nsk;
L
Linus Torvalds 已提交
1580
				goto reset;
1581
			}
L
Linus Torvalds 已提交
1582 1583 1584 1585 1586
			return 0;
		}
	}

	TCP_CHECK_TIMER(sk);
1587
	if (tcp_rcv_state_process(sk, skb, tcp_hdr(skb), skb->len)) {
1588
		rsk = sk;
L
Linus Torvalds 已提交
1589
		goto reset;
1590
	}
L
Linus Torvalds 已提交
1591 1592 1593 1594
	TCP_CHECK_TIMER(sk);
	return 0;

reset:
1595
	tcp_v4_send_reset(rsk, skb);
L
Linus Torvalds 已提交
1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615
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)
{
1616
	const struct iphdr *iph;
L
Linus Torvalds 已提交
1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629
	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;

1630
	th = tcp_hdr(skb);
L
Linus Torvalds 已提交
1631 1632 1633 1634 1635 1636 1637 1638

	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
1639
	 * provided case of th->doff==0 is eliminated.
L
Linus Torvalds 已提交
1640 1641
	 * So, we defer the checks. */
	if ((skb->ip_summed != CHECKSUM_UNNECESSARY &&
1642
	     tcp_v4_checksum_init(skb)))
L
Linus Torvalds 已提交
1643 1644
		goto bad_packet;

1645
	th = tcp_hdr(skb);
1646
	iph = ip_hdr(skb);
L
Linus Torvalds 已提交
1647 1648 1649 1650 1651
	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;
1652
	TCP_SKB_CB(skb)->flags	 = iph->tos;
L
Linus Torvalds 已提交
1653 1654
	TCP_SKB_CB(skb)->sacked	 = 0;

1655 1656
	sk = __inet_lookup(&tcp_hashinfo, iph->saddr, th->source,
			   iph->daddr, th->dest, inet_iif(skb));
L
Linus Torvalds 已提交
1657 1658 1659 1660 1661 1662 1663 1664 1665
	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;
1666
	nf_reset(skb);
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Linus Torvalds 已提交
1667

1668
	if (sk_filter(sk, skb))
L
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1669 1670 1671 1672
		goto discard_and_relse;

	skb->dev = NULL;

1673
	bh_lock_sock_nested(sk);
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1674 1675
	ret = 0;
	if (!sock_owned_by_user(sk)) {
C
Chris Leech 已提交
1676 1677 1678 1679 1680
#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)
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1681
			ret = tcp_v4_do_rcv(sk, skb);
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1682 1683 1684 1685 1686 1687
		else
#endif
		{
			if (!tcp_prequeue(sk, skb))
			ret = tcp_v4_do_rcv(sk, skb);
		}
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1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703
	} 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 {
1704
		tcp_v4_send_reset(NULL, skb);
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	}

discard_it:
	/* Discard frame. */
	kfree_skb(skb);
1710
	return 0;
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discard_and_relse:
	sock_put(sk);
	goto discard_it;

do_time_wait:
	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1718
		inet_twsk_put(inet_twsk(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);
1724
		inet_twsk_put(inet_twsk(sk));
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		goto discard_it;
	}
1727
	switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
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1728
	case TCP_TW_SYN: {
1729
		struct sock *sk2 = inet_lookup_listener(&tcp_hashinfo,
1730
							iph->daddr, th->dest,
1731
							inet_iif(skb));
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Linus Torvalds 已提交
1732
		if (sk2) {
1733 1734
			inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
			inet_twsk_put(inet_twsk(sk));
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1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774
			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 ||
1775
		    (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() &&
L
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1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787
		     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;
}

1788
int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw)
L
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1789
{
1790
	struct inet_peer *peer = inet_getpeer(tw->tw_daddr, 1);
L
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	if (peer) {
1793 1794 1795
		const struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);

		if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 ||
1796
		    (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() &&
1797 1798 1799
		     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;
}

1808
struct inet_connection_sock_af_ops ipv4_specific = {
1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819
	.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),
1820
#ifdef CONFIG_COMPAT
1821 1822
	.compat_setsockopt = compat_ip_setsockopt,
	.compat_getsockopt = compat_ip_getsockopt,
1823
#endif
L
Linus Torvalds 已提交
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};

1826
#ifdef CONFIG_TCP_MD5SIG
1827
static struct tcp_sock_af_ops tcp_sock_ipv4_specific = {
1828 1829 1830 1831 1832
	.md5_lookup		= tcp_v4_md5_lookup,
	.calc_md5_hash		= tcp_v4_calc_md5_hash,
	.md5_add		= tcp_v4_md5_add_func,
	.md5_parse		= tcp_v4_parse_md5_keys,
};
1833
#endif
1834

L
Linus Torvalds 已提交
1835 1836 1837 1838 1839
/* 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)
{
1840
	struct inet_connection_sock *icsk = inet_csk(sk);
L
Linus Torvalds 已提交
1841 1842 1843 1844 1845 1846
	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);

1847
	icsk->icsk_rto = TCP_TIMEOUT_INIT;
L
Linus Torvalds 已提交
1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861
	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;
1862
	tp->mss_cache = 536;
L
Linus Torvalds 已提交
1863 1864

	tp->reordering = sysctl_tcp_reordering;
1865
	icsk->icsk_ca_ops = &tcp_init_congestion_ops;
L
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1866 1867 1868 1869 1870 1871

	sk->sk_state = TCP_CLOSE;

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

1872
	icsk->icsk_af_ops = &ipv4_specific;
1873
	icsk->icsk_sync_mss = tcp_sync_mss;
1874 1875 1876
#ifdef CONFIG_TCP_MD5SIG
	tp->af_specific = &tcp_sock_ipv4_specific;
#endif
L
Linus Torvalds 已提交
1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891

	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);

1892
	tcp_cleanup_congestion_control(sk);
1893

L
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1894
	/* Cleanup up the write buffer. */
1895
	tcp_write_queue_purge(sk);
L
Linus Torvalds 已提交
1896 1897

	/* Cleans up our, hopefully empty, out_of_order_queue. */
1898
	__skb_queue_purge(&tp->out_of_order_queue);
L
Linus Torvalds 已提交
1899

1900 1901 1902 1903 1904 1905 1906 1907 1908
#ifdef CONFIG_TCP_MD5SIG
	/* Clean up the MD5 key list, if any */
	if (tp->md5sig_info) {
		tcp_v4_clear_md5_list(sk);
		kfree(tp->md5sig_info);
		tp->md5sig_info = NULL;
	}
#endif

C
Chris Leech 已提交
1909 1910
#ifdef CONFIG_NET_DMA
	/* Cleans up our sk_async_wait_queue */
1911
	__skb_queue_purge(&sk->sk_async_wait_queue);
C
Chris Leech 已提交
1912 1913
#endif

L
Linus Torvalds 已提交
1914 1915 1916 1917
	/* Clean prequeue, it must be empty really */
	__skb_queue_purge(&tp->ucopy.prequeue);

	/* Clean up a referenced TCP bind bucket. */
1918
	if (inet_csk(sk)->icsk_bind_hash)
1919
		inet_put_port(&tcp_hashinfo, sk);
L
Linus Torvalds 已提交
1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938

	/*
	 * 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. */

1939
static inline struct inet_timewait_sock *tw_head(struct hlist_head *head)
L
Linus Torvalds 已提交
1940 1941
{
	return hlist_empty(head) ? NULL :
1942
		list_entry(head->first, struct inet_timewait_sock, tw_node);
L
Linus Torvalds 已提交
1943 1944
}

1945
static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw)
L
Linus Torvalds 已提交
1946 1947 1948 1949 1950 1951 1952
{
	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)
{
1953
	struct inet_connection_sock *icsk;
L
Linus Torvalds 已提交
1954 1955 1956 1957 1958 1959
	struct hlist_node *node;
	struct sock *sk = cur;
	struct tcp_iter_state* st = seq->private;

	if (!sk) {
		st->bucket = 0;
1960
		sk = sk_head(&tcp_hashinfo.listening_hash[0]);
L
Linus Torvalds 已提交
1961 1962 1963 1964 1965 1966
		goto get_sk;
	}

	++st->num;

	if (st->state == TCP_SEQ_STATE_OPENREQ) {
1967
		struct request_sock *req = cur;
L
Linus Torvalds 已提交
1968

1969
		icsk = inet_csk(st->syn_wait_sk);
L
Linus Torvalds 已提交
1970 1971 1972
		req = req->dl_next;
		while (1) {
			while (req) {
1973
				if (req->rsk_ops->family == st->family) {
L
Linus Torvalds 已提交
1974 1975 1976 1977 1978
					cur = req;
					goto out;
				}
				req = req->dl_next;
			}
1979
			if (++st->sbucket >= icsk->icsk_accept_queue.listen_opt->nr_table_entries)
L
Linus Torvalds 已提交
1980 1981
				break;
get_req:
1982
			req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];
L
Linus Torvalds 已提交
1983 1984 1985
		}
		sk	  = sk_next(st->syn_wait_sk);
		st->state = TCP_SEQ_STATE_LISTENING;
1986
		read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
L
Linus Torvalds 已提交
1987
	} else {
1988
		icsk = inet_csk(sk);
1989 1990
		read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
		if (reqsk_queue_len(&icsk->icsk_accept_queue))
L
Linus Torvalds 已提交
1991
			goto start_req;
1992
		read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
L
Linus Torvalds 已提交
1993 1994 1995 1996 1997 1998 1999 2000
		sk = sk_next(sk);
	}
get_sk:
	sk_for_each_from(sk, node) {
		if (sk->sk_family == st->family) {
			cur = sk;
			goto out;
		}
2001
		icsk = inet_csk(sk);
2002 2003
		read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
		if (reqsk_queue_len(&icsk->icsk_accept_queue)) {
L
Linus Torvalds 已提交
2004 2005 2006 2007 2008 2009 2010
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;
		}
2011
		read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
L
Linus Torvalds 已提交
2012
	}
2013
	if (++st->bucket < INET_LHTABLE_SIZE) {
2014
		sk = sk_head(&tcp_hashinfo.listening_hash[st->bucket]);
L
Linus Torvalds 已提交
2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037
		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;

2038
	for (st->bucket = 0; st->bucket < tcp_hashinfo.ehash_size; ++st->bucket) {
L
Linus Torvalds 已提交
2039 2040
		struct sock *sk;
		struct hlist_node *node;
2041
		struct inet_timewait_sock *tw;
L
Linus Torvalds 已提交
2042 2043 2044 2045

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

2046 2047
		read_lock(&tcp_hashinfo.ehash[st->bucket].lock);
		sk_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
L
Linus Torvalds 已提交
2048 2049 2050 2051 2052 2053 2054
			if (sk->sk_family != st->family) {
				continue;
			}
			rc = sk;
			goto out;
		}
		st->state = TCP_SEQ_STATE_TIME_WAIT;
2055
		inet_twsk_for_each(tw, node,
2056
				   &tcp_hashinfo.ehash[st->bucket].twchain) {
L
Linus Torvalds 已提交
2057 2058 2059 2060 2061 2062
			if (tw->tw_family != st->family) {
				continue;
			}
			rc = tw;
			goto out;
		}
2063
		read_unlock(&tcp_hashinfo.ehash[st->bucket].lock);
L
Linus Torvalds 已提交
2064 2065 2066 2067 2068 2069 2070 2071 2072
		st->state = TCP_SEQ_STATE_ESTABLISHED;
	}
out:
	return rc;
}

static void *established_get_next(struct seq_file *seq, void *cur)
{
	struct sock *sk = cur;
2073
	struct inet_timewait_sock *tw;
L
Linus Torvalds 已提交
2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089
	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;
		}
2090
		read_unlock(&tcp_hashinfo.ehash[st->bucket].lock);
L
Linus Torvalds 已提交
2091 2092 2093 2094 2095
		st->state = TCP_SEQ_STATE_ESTABLISHED;

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

2096 2097 2098
		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
Linus Torvalds 已提交
2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111
		} 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;
2112
	tw = tw_head(&tcp_hashinfo.ehash[st->bucket].twchain);
L
Linus Torvalds 已提交
2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126
	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;
2127
	}
L
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2128 2129 2130 2131 2132 2133 2134 2135
	return rc;
}

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

2136
	inet_listen_lock(&tcp_hashinfo);
L
Linus Torvalds 已提交
2137 2138 2139 2140
	st->state = TCP_SEQ_STATE_LISTENING;
	rc	  = listening_get_idx(seq, &pos);

	if (!rc) {
2141
		inet_listen_unlock(&tcp_hashinfo);
L
Linus Torvalds 已提交
2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173
		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) {
2174
			inet_listen_unlock(&tcp_hashinfo);
L
Linus Torvalds 已提交
2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196
			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) {
2197 2198
			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
2199 2200 2201
		}
	case TCP_SEQ_STATE_LISTENING:
		if (v != SEQ_START_TOKEN)
2202
			inet_listen_unlock(&tcp_hashinfo);
L
Linus Torvalds 已提交
2203 2204 2205 2206
		break;
	case TCP_SEQ_STATE_TIME_WAIT:
	case TCP_SEQ_STATE_ESTABLISHED:
		if (v)
2207
			read_unlock(&tcp_hashinfo.ehash[st->bucket].lock);
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		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;

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	s = kzalloc(sizeof(*s), GFP_KERNEL);
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	if (!s)
		return -ENOMEM;
	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;
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	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);
2270
	memset(afinfo->seq_fops, 0, sizeof(*afinfo->seq_fops));
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}

2273
static void get_openreq4(struct sock *sk, struct request_sock *req,
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			 char *tmpbuf, int i, int uid)
{
2276
	const struct inet_request_sock *ireq = inet_rsk(req);
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	int ttd = req->expires - jiffies;

	sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X"
		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %p",
		i,
2282
		ireq->loc_addr,
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		ntohs(inet_sk(sk)->sport),
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		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);
}

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static void get_tcp4_sock(struct sock *sk, char *tmpbuf, int i)
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{
	int timer_active;
	unsigned long timer_expires;
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	struct tcp_sock *tp = tcp_sk(sk);
	const struct inet_connection_sock *icsk = inet_csk(sk);
	struct inet_sock *inet = inet_sk(sk);
2305 2306
	__be32 dest = inet->daddr;
	__be32 src = inet->rcv_saddr;
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	__u16 destp = ntohs(inet->dport);
	__u16 srcp = ntohs(inet->sport);

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	if (icsk->icsk_pending == ICSK_TIME_RETRANS) {
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		timer_active	= 1;
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		timer_expires	= icsk->icsk_timeout;
	} else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
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		timer_active	= 4;
2315
		timer_expires	= icsk->icsk_timeout;
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	} else if (timer_pending(&sk->sk_timer)) {
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		timer_active	= 2;
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		timer_expires	= sk->sk_timer.expires;
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	} 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",
2326
		i, src, srcp, dest, destp, sk->sk_state,
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		tp->write_seq - tp->snd_una,
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		sk->sk_state == TCP_LISTEN ? sk->sk_ack_backlog :
2329
					     (tp->rcv_nxt - tp->copied_seq),
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		timer_active,
		jiffies_to_clock_t(timer_expires - jiffies),
2332
		icsk->icsk_retransmits,
2333
		sock_i_uid(sk),
2334
		icsk->icsk_probes_out,
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		sock_i_ino(sk),
		atomic_read(&sk->sk_refcnt), sk,
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		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);
}

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static void get_timewait4_sock(struct inet_timewait_sock *tw,
			       char *tmpbuf, int i)
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{
2347
	__be32 dest, src;
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	__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,
2425
	.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,
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	.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),
2448
	.twsk_prot		= &tcp_timewait_sock_ops,
2449
	.rsk_prot		= &tcp_request_sock_ops,
2450 2451 2452 2453
#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)
{
2458 2459
	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);