tcp_ipv4.c 65.9 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).
 *
 *		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.
 */


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#include <linux/bottom_half.h>
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#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>
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#include <linux/slab.h>
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#include <net/net_namespace.h>
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#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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EXPORT_SYMBOL(sysctl_tcp_low_latency);
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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_md5_hash_hdr(char *md5_hash, struct tcp_md5sig_key *key,
			       __be32 daddr, __be32 saddr, struct tcphdr *th);
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#else
static inline
struct tcp_md5sig_key *tcp_v4_md5_do_lookup(struct sock *sk, __be32 addr)
{
	return NULL;
}
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#endif

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struct inet_hashinfo tcp_hashinfo;
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EXPORT_SYMBOL(tcp_hashinfo);
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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;
	}

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	tmp = ip_route_connect(&rt, nexthop, inet->inet_saddr,
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			       RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
			       IPPROTO_TCP,
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			       inet->inet_sport, usin->sin_port, sk, 1);
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	if (tmp < 0) {
		if (tmp == -ENETUNREACH)
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			IP_INC_STATS_BH(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
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		return tmp;
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	}
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	if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
		ip_rt_put(rt);
		return -ENETUNREACH;
	}

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

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	if (!inet->inet_saddr)
		inet->inet_saddr = rt->rt_src;
	inet->inet_rcv_saddr = inet->inet_saddr;
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	if (tp->rx_opt.ts_recent_stamp && inet->inet_daddr != daddr) {
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		/* 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) {
			inet_peer_refcheck(peer);
			if ((u32)get_seconds() - peer->tcp_ts_stamp <= TCP_PAWS_MSL) {
				tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp;
				tp->rx_opt.ts_recent = peer->tcp_ts;
			}
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		}
	}

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	inet->inet_dport = usin->sin_port;
	inet->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 = TCP_MSS_DEFAULT;
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	/* 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,
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				inet->inet_sport, inet->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->dst);
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	if (!tp->write_seq)
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		tp->write_seq = secure_tcp_sequence_number(inet->inet_saddr,
							   inet->inet_daddr,
							   inet->inet_sport,
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							   usin->sin_port);

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	inet->inet_id = tp->write_seq ^ jiffies;
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	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;
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	inet->inet_dport = 0;
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	return err;
}
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EXPORT_SYMBOL(tcp_v4_connect);
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/*
 * 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.
 *
 */

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void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
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{
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	struct iphdr *iph = (struct iphdr *)icmp_skb->data;
	struct tcphdr *th = (struct tcphdr *)(icmp_skb->data + (iph->ihl << 2));
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	struct inet_connection_sock *icsk;
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	struct tcp_sock *tp;
	struct inet_sock *inet;
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	const int type = icmp_hdr(icmp_skb)->type;
	const int code = icmp_hdr(icmp_skb)->code;
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	struct sock *sk;
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	struct sk_buff *skb;
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	__u32 seq;
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	__u32 remaining;
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	int err;
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	struct net *net = dev_net(icmp_skb->dev);
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	if (icmp_skb->len < (iph->ihl << 2) + 8) {
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		ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
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		return;
	}

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	sk = inet_lookup(net, &tcp_hashinfo, iph->daddr, th->dest,
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			iph->saddr, th->source, inet_iif(icmp_skb));
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	if (!sk) {
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		ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
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		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))
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		NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
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	if (sk->sk_state == TCP_CLOSE)
		goto out;

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	if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) {
		NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
		goto out;
	}

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	icsk = inet_csk(sk);
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	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(net, 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;
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		/* check if icmp_skb allows revert of backoff
		 * (see draft-zimmermann-tcp-lcd) */
		if (code != ICMP_NET_UNREACH && code != ICMP_HOST_UNREACH)
			break;
		if (seq != tp->snd_una  || !icsk->icsk_retransmits ||
		    !icsk->icsk_backoff)
			break;

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		if (sock_owned_by_user(sk))
			break;

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		icsk->icsk_backoff--;
		inet_csk(sk)->icsk_rto = __tcp_set_rto(tp) <<
					 icsk->icsk_backoff;
		tcp_bound_rto(sk);

		skb = tcp_write_queue_head(sk);
		BUG_ON(!skb);

		remaining = icsk->icsk_rto - min(icsk->icsk_rto,
				tcp_time_stamp - TCP_SKB_CB(skb)->when);

		if (remaining) {
			inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
						  remaining, TCP_RTO_MAX);
		} else {
			/* RTO revert clocked out retransmission.
			 * Will retransmit now */
			tcp_retransmit_timer(sk);
		}

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		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.
		 */
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		WARN_ON(req->sk);
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		if (seq != tcp_rsk(req)->snt_isn) {
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			NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
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			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);
}

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static void __tcp_v4_send_check(struct sk_buff *skb,
				__be32 saddr, __be32 daddr)
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{
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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(skb->len, saddr, 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(skb->len, saddr, daddr,
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					 csum_partial(th,
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						      th->doff << 2,
						      skb->csum));
	}
}

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/* This routine computes an IPv4 TCP checksum. */
542
void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb)
543 544 545 546 547
{
	struct inet_sock *inet = inet_sk(sk);

	__tcp_v4_send_check(skb, inet->inet_saddr, inet->inet_daddr);
}
E
Eric Dumazet 已提交
548
EXPORT_SYMBOL(tcp_v4_send_check);
549

550 551
int tcp_v4_gso_send_check(struct sk_buff *skb)
{
552
	const struct iphdr *iph;
553 554 555 556 557
	struct tcphdr *th;

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

558
	iph = ip_hdr(skb);
559
	th = tcp_hdr(skb);
560 561

	th->check = 0;
562
	skb->ip_summed = CHECKSUM_PARTIAL;
563
	__tcp_v4_send_check(skb, iph->saddr, iph->daddr);
564 565 566
	return 0;
}

L
Linus Torvalds 已提交
567 568 569 570 571 572 573 574 575 576 577 578 579
/*
 *	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.
 */

580
static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
L
Linus Torvalds 已提交
581
{
582
	struct tcphdr *th = tcp_hdr(skb);
583 584 585
	struct {
		struct tcphdr th;
#ifdef CONFIG_TCP_MD5SIG
586
		__be32 opt[(TCPOLEN_MD5SIG_ALIGNED >> 2)];
587 588
#endif
	} rep;
L
Linus Torvalds 已提交
589
	struct ip_reply_arg arg;
590 591 592
#ifdef CONFIG_TCP_MD5SIG
	struct tcp_md5sig_key *key;
#endif
593
	struct net *net;
L
Linus Torvalds 已提交
594 595 596 597 598

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

E
Eric Dumazet 已提交
599
	if (skb_rtable(skb)->rt_type != RTN_LOCAL)
L
Linus Torvalds 已提交
600 601 602
		return;

	/* Swap the send and the receive. */
603 604 605 606 607
	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;
L
Linus Torvalds 已提交
608 609

	if (th->ack) {
610
		rep.th.seq = th->ack_seq;
L
Linus Torvalds 已提交
611
	} else {
612 613 614
		rep.th.ack = 1;
		rep.th.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin +
				       skb->len - (th->doff << 2));
L
Linus Torvalds 已提交
615 616
	}

617
	memset(&arg, 0, sizeof(arg));
618 619 620 621
	arg.iov[0].iov_base = (unsigned char *)&rep;
	arg.iov[0].iov_len  = sizeof(rep.th);

#ifdef CONFIG_TCP_MD5SIG
622
	key = sk ? tcp_v4_md5_do_lookup(sk, ip_hdr(skb)->daddr) : NULL;
623 624 625 626 627 628 629 630 631
	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;

632
		tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[1],
633 634
				     key, ip_hdr(skb)->saddr,
				     ip_hdr(skb)->daddr, &rep.th);
635 636
	}
#endif
637 638
	arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
				      ip_hdr(skb)->saddr, /* XXX */
639
				      arg.iov[0].iov_len, IPPROTO_TCP, 0);
L
Linus Torvalds 已提交
640
	arg.csumoffset = offsetof(struct tcphdr, check) / 2;
641
	arg.flags = (sk && inet_sk(sk)->transparent) ? IP_REPLY_ARG_NOSRCCHECK : 0;
L
Linus Torvalds 已提交
642

E
Eric Dumazet 已提交
643
	net = dev_net(skb_dst(skb)->dev);
644
	ip_send_reply(net->ipv4.tcp_sock, skb,
645
		      &arg, arg.iov[0].iov_len);
L
Linus Torvalds 已提交
646

647 648
	TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
	TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS);
L
Linus Torvalds 已提交
649 650 651 652 653 654
}

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

655 656
static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
			    u32 win, u32 ts, int oif,
657 658
			    struct tcp_md5sig_key *key,
			    int reply_flags)
L
Linus Torvalds 已提交
659
{
660
	struct tcphdr *th = tcp_hdr(skb);
L
Linus Torvalds 已提交
661 662
	struct {
		struct tcphdr th;
663
		__be32 opt[(TCPOLEN_TSTAMP_ALIGNED >> 2)
664
#ifdef CONFIG_TCP_MD5SIG
665
			   + (TCPOLEN_MD5SIG_ALIGNED >> 2)
666 667
#endif
			];
L
Linus Torvalds 已提交
668 669
	} rep;
	struct ip_reply_arg arg;
E
Eric Dumazet 已提交
670
	struct net *net = dev_net(skb_dst(skb)->dev);
L
Linus Torvalds 已提交
671 672

	memset(&rep.th, 0, sizeof(struct tcphdr));
673
	memset(&arg, 0, sizeof(arg));
L
Linus Torvalds 已提交
674 675 676 677

	arg.iov[0].iov_base = (unsigned char *)&rep;
	arg.iov[0].iov_len  = sizeof(rep.th);
	if (ts) {
678 679 680 681 682
		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);
683
		arg.iov[0].iov_len += TCPOLEN_TSTAMP_ALIGNED;
L
Linus Torvalds 已提交
684 685 686 687 688 689 690 691 692 693 694
	}

	/* 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);

695 696 697 698 699 700 701 702 703 704 705
#ifdef CONFIG_TCP_MD5SIG
	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;

706
		tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[offset],
707 708
				    key, ip_hdr(skb)->saddr,
				    ip_hdr(skb)->daddr, &rep.th);
709 710
	}
#endif
711
	arg.flags = reply_flags;
712 713
	arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
				      ip_hdr(skb)->saddr, /* XXX */
L
Linus Torvalds 已提交
714 715
				      arg.iov[0].iov_len, IPPROTO_TCP, 0);
	arg.csumoffset = offsetof(struct tcphdr, check) / 2;
716 717
	if (oif)
		arg.bound_dev_if = oif;
L
Linus Torvalds 已提交
718

719
	ip_send_reply(net->ipv4.tcp_sock, skb,
720
		      &arg, arg.iov[0].iov_len);
L
Linus Torvalds 已提交
721

722
	TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
L
Linus Torvalds 已提交
723 724 725 726
}

static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
{
727
	struct inet_timewait_sock *tw = inet_twsk(sk);
728
	struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
L
Linus Torvalds 已提交
729

730
	tcp_v4_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
731
			tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
732 733
			tcptw->tw_ts_recent,
			tw->tw_bound_dev_if,
734 735
			tcp_twsk_md5_key(tcptw),
			tw->tw_transparent ? IP_REPLY_ARG_NOSRCCHECK : 0
736
			);
L
Linus Torvalds 已提交
737

738
	inet_twsk_put(tw);
L
Linus Torvalds 已提交
739 740
}

741
static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
742
				  struct request_sock *req)
L
Linus Torvalds 已提交
743
{
744
	tcp_v4_send_ack(skb, tcp_rsk(req)->snt_isn + 1,
745
			tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd,
746 747
			req->ts_recent,
			0,
748 749
			tcp_v4_md5_do_lookup(sk, ip_hdr(skb)->daddr),
			inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0);
L
Linus Torvalds 已提交
750 751 752
}

/*
753
 *	Send a SYN-ACK after having received a SYN.
754
 *	This still operates on a request_sock only, not on a big
L
Linus Torvalds 已提交
755 756
 *	socket.
 */
757 758 759
static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst,
			      struct request_sock *req,
			      struct request_values *rvp)
L
Linus Torvalds 已提交
760
{
761
	const struct inet_request_sock *ireq = inet_rsk(req);
L
Linus Torvalds 已提交
762 763 764 765
	int err = -1;
	struct sk_buff * skb;

	/* First, grab a route. */
766
	if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
767
		return -1;
L
Linus Torvalds 已提交
768

769
	skb = tcp_make_synack(sk, dst, req, rvp);
L
Linus Torvalds 已提交
770 771

	if (skb) {
772
		__tcp_v4_send_check(skb, ireq->loc_addr, ireq->rmt_addr);
L
Linus Torvalds 已提交
773

774 775 776
		err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
					    ireq->rmt_addr,
					    ireq->opt);
777
		err = net_xmit_eval(err);
L
Linus Torvalds 已提交
778 779 780 781 782 783
	}

	dst_release(dst);
	return err;
}

784
static int tcp_v4_rtx_synack(struct sock *sk, struct request_sock *req,
785
			      struct request_values *rvp)
786
{
787 788
	TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_RETRANSSEGS);
	return tcp_v4_send_synack(sk, NULL, req, rvp);
789 790
}

L
Linus Torvalds 已提交
791
/*
792
 *	IPv4 request_sock destructor.
L
Linus Torvalds 已提交
793
 */
794
static void tcp_v4_reqsk_destructor(struct request_sock *req)
L
Linus Torvalds 已提交
795
{
J
Jesper Juhl 已提交
796
	kfree(inet_rsk(req)->opt);
L
Linus Torvalds 已提交
797 798
}

799
static void syn_flood_warning(const struct sk_buff *skb)
L
Linus Torvalds 已提交
800
{
801
	const char *msg;
L
Linus Torvalds 已提交
802

803 804 805 806
#ifdef CONFIG_SYN_COOKIES
	if (sysctl_tcp_syncookies)
		msg = "Sending cookies";
	else
807
#endif
808 809 810 811 812
		msg = "Dropping request";

	pr_info("TCP: Possible SYN flooding on port %d. %s.\n",
				ntohs(tcp_hdr(skb)->dest), msg);
}
L
Linus Torvalds 已提交
813 814

/*
815
 * Save and compile IPv4 options into the request_sock if needed.
L
Linus Torvalds 已提交
816
 */
S
Stephen Hemminger 已提交
817 818
static struct ip_options *tcp_v4_save_options(struct sock *sk,
					      struct sk_buff *skb)
L
Linus Torvalds 已提交
819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835
{
	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;
}

836 837 838 839 840 841 842 843
#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.  */
844 845
static struct tcp_md5sig_key *
			tcp_v4_md5_do_lookup(struct sock *sk, __be32 addr)
846 847 848 849 850 851 852 853
{
	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)
854
			return &tp->md5sig_info->keys4[i].base;
855 856 857 858 859 860 861
	}
	return NULL;
}

struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
					 struct sock *addr_sk)
{
E
Eric Dumazet 已提交
862
	return tcp_v4_md5_do_lookup(sk, inet_sk(addr_sk)->inet_daddr);
863 864 865
}
EXPORT_SYMBOL(tcp_v4_md5_lookup);

A
Adrian Bunk 已提交
866 867
static struct tcp_md5sig_key *tcp_v4_reqsk_md5_lookup(struct sock *sk,
						      struct request_sock *req)
868 869 870 871 872 873 874 875 876
{
	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 */
877
	struct tcp_md5sig_key *key;
878 879 880
	struct tcp_sock *tp = tcp_sk(sk);
	struct tcp4_md5sig_key *keys;

881
	key = tcp_v4_md5_do_lookup(sk, addr);
882 883
	if (key) {
		/* Pre-existing entry - just update that one. */
884 885 886
		kfree(key->key);
		key->key = newkey;
		key->keylen = newkeylen;
887
	} else {
888 889
		struct tcp_md5sig_info *md5sig;

890
		if (!tp->md5sig_info) {
891 892
			tp->md5sig_info = kzalloc(sizeof(*tp->md5sig_info),
						  GFP_ATOMIC);
893 894 895 896
			if (!tp->md5sig_info) {
				kfree(newkey);
				return -ENOMEM;
			}
E
Eric Dumazet 已提交
897
			sk_nocaps_add(sk, NETIF_F_GSO_MASK);
898
		}
899
		if (tcp_alloc_md5sig_pool(sk) == NULL) {
900 901 902
			kfree(newkey);
			return -ENOMEM;
		}
903 904 905 906
		md5sig = tp->md5sig_info;

		if (md5sig->alloced4 == md5sig->entries4) {
			keys = kmalloc((sizeof(*keys) *
907
					(md5sig->entries4 + 1)), GFP_ATOMIC);
908 909 910 911 912 913
			if (!keys) {
				kfree(newkey);
				tcp_free_md5sig_pool();
				return -ENOMEM;
			}

914 915 916
			if (md5sig->entries4)
				memcpy(keys, md5sig->keys4,
				       sizeof(*keys) * md5sig->entries4);
917 918

			/* Free old key list, and reference new one */
919
			kfree(md5sig->keys4);
920 921
			md5sig->keys4 = keys;
			md5sig->alloced4++;
922
		}
923
		md5sig->entries4++;
924 925 926
		md5sig->keys4[md5sig->entries4 - 1].addr        = addr;
		md5sig->keys4[md5sig->entries4 - 1].base.key    = newkey;
		md5sig->keys4[md5sig->entries4 - 1].base.keylen = newkeylen;
927 928 929 930 931 932 933 934
	}
	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)
{
E
Eric Dumazet 已提交
935
	return tcp_v4_md5_do_add(sk, inet_sk(addr_sk)->inet_daddr,
936 937 938 939 940 941 942 943 944 945 946
				 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 */
947
			kfree(tp->md5sig_info->keys4[i].base.key);
948 949 950 951 952
			tp->md5sig_info->entries4--;

			if (tp->md5sig_info->entries4 == 0) {
				kfree(tp->md5sig_info->keys4);
				tp->md5sig_info->keys4 = NULL;
953
				tp->md5sig_info->alloced4 = 0;
954
			} else if (tp->md5sig_info->entries4 != i) {
955
				/* Need to do some manipulation */
956 957 958 959
				memmove(&tp->md5sig_info->keys4[i],
					&tp->md5sig_info->keys4[i+1],
					(tp->md5sig_info->entries4 - i) *
					 sizeof(struct tcp4_md5sig_key));
960 961 962 963 964 965 966 967 968
			}
			tcp_free_md5sig_pool();
			return 0;
		}
	}
	return -ENOENT;
}
EXPORT_SYMBOL(tcp_v4_md5_do_del);

969
static void tcp_v4_clear_md5_list(struct sock *sk)
970 971 972 973 974 975 976 977 978 979
{
	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++)
980
			kfree(tp->md5sig_info->keys4[i].base.key);
981 982 983 984 985 986 987 988 989 990
		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;
	}
}

991 992
static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval,
				 int optlen)
993 994 995 996 997 998 999 1000
{
	struct tcp_md5sig cmd;
	struct sockaddr_in *sin = (struct sockaddr_in *)&cmd.tcpm_addr;
	u8 *newkey;

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

1001
	if (copy_from_user(&cmd, optval, sizeof(cmd)))
1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017
		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);
1018
		struct tcp_md5sig_info *p;
1019

1020
		p = kzalloc(sizeof(*p), sk->sk_allocation);
1021 1022 1023 1024
		if (!p)
			return -EINVAL;

		tp->md5sig_info = p;
E
Eric Dumazet 已提交
1025
		sk_nocaps_add(sk, NETIF_F_GSO_MASK);
1026 1027
	}

1028
	newkey = kmemdup(cmd.tcpm_key, cmd.tcpm_keylen, sk->sk_allocation);
1029 1030 1031 1032 1033 1034
	if (!newkey)
		return -ENOMEM;
	return tcp_v4_md5_do_add(sk, sin->sin_addr.s_addr,
				 newkey, cmd.tcpm_keylen);
}

1035 1036
static int tcp_v4_md5_hash_pseudoheader(struct tcp_md5sig_pool *hp,
					__be32 daddr, __be32 saddr, int nbytes)
1037 1038
{
	struct tcp4_pseudohdr *bp;
1039
	struct scatterlist sg;
1040 1041 1042 1043

	bp = &hp->md5_blk.ip4;

	/*
1044
	 * 1. the TCP pseudo-header (in the order: source IP address,
1045 1046 1047 1048 1049 1050
	 * destination IP address, zero-padded protocol number, and
	 * segment length)
	 */
	bp->saddr = saddr;
	bp->daddr = daddr;
	bp->pad = 0;
1051
	bp->protocol = IPPROTO_TCP;
1052
	bp->len = cpu_to_be16(nbytes);
1053

1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077
	sg_init_one(&sg, bp, sizeof(*bp));
	return crypto_hash_update(&hp->md5_desc, &sg, sizeof(*bp));
}

static int tcp_v4_md5_hash_hdr(char *md5_hash, struct tcp_md5sig_key *key,
			       __be32 daddr, __be32 saddr, struct tcphdr *th)
{
	struct tcp_md5sig_pool *hp;
	struct hash_desc *desc;

	hp = tcp_get_md5sig_pool();
	if (!hp)
		goto clear_hash_noput;
	desc = &hp->md5_desc;

	if (crypto_hash_init(desc))
		goto clear_hash;
	if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, th->doff << 2))
		goto clear_hash;
	if (tcp_md5_hash_header(hp, th))
		goto clear_hash;
	if (tcp_md5_hash_key(hp, key))
		goto clear_hash;
	if (crypto_hash_final(desc, md5_hash))
1078 1079 1080 1081
		goto clear_hash;

	tcp_put_md5sig_pool();
	return 0;
1082

1083 1084 1085 1086
clear_hash:
	tcp_put_md5sig_pool();
clear_hash_noput:
	memset(md5_hash, 0, 16);
1087
	return 1;
1088 1089
}

1090 1091 1092
int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
			struct sock *sk, struct request_sock *req,
			struct sk_buff *skb)
1093
{
1094 1095 1096
	struct tcp_md5sig_pool *hp;
	struct hash_desc *desc;
	struct tcphdr *th = tcp_hdr(skb);
1097 1098 1099
	__be32 saddr, daddr;

	if (sk) {
E
Eric Dumazet 已提交
1100 1101
		saddr = inet_sk(sk)->inet_saddr;
		daddr = inet_sk(sk)->inet_daddr;
1102 1103 1104
	} else if (req) {
		saddr = inet_rsk(req)->loc_addr;
		daddr = inet_rsk(req)->rmt_addr;
1105
	} else {
1106 1107 1108
		const struct iphdr *iph = ip_hdr(skb);
		saddr = iph->saddr;
		daddr = iph->daddr;
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

	hp = tcp_get_md5sig_pool();
	if (!hp)
		goto clear_hash_noput;
	desc = &hp->md5_desc;

	if (crypto_hash_init(desc))
		goto clear_hash;

	if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, skb->len))
		goto clear_hash;
	if (tcp_md5_hash_header(hp, th))
		goto clear_hash;
	if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2))
		goto clear_hash;
	if (tcp_md5_hash_key(hp, key))
		goto clear_hash;
	if (crypto_hash_final(desc, md5_hash))
		goto clear_hash;

	tcp_put_md5sig_pool();
	return 0;

clear_hash:
	tcp_put_md5sig_pool();
clear_hash_noput:
	memset(md5_hash, 0, 16);
	return 1;
1138
}
1139
EXPORT_SYMBOL(tcp_v4_md5_hash_skb);
1140

1141
static int tcp_v4_inbound_md5_hash(struct sock *sk, struct sk_buff *skb)
1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152
{
	/*
	 * 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;
1153
	const struct iphdr *iph = ip_hdr(skb);
1154
	struct tcphdr *th = tcp_hdr(skb);
1155 1156 1157 1158
	int genhash;
	unsigned char newhash[16];

	hash_expected = tcp_v4_md5_do_lookup(sk, iph->saddr);
1159
	hash_location = tcp_parse_md5sig_option(th);
1160 1161 1162 1163 1164 1165

	/* We've parsed the options - do we have a hash? */
	if (!hash_expected && !hash_location)
		return 0;

	if (hash_expected && !hash_location) {
1166
		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
1167 1168 1169 1170
		return 1;
	}

	if (!hash_expected && hash_location) {
1171
		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
1172 1173 1174 1175 1176 1177
		return 1;
	}

	/* Okay, so this is hash_expected and hash_location -
	 * so we need to calculate the checksum.
	 */
1178 1179 1180
	genhash = tcp_v4_md5_hash_skb(newhash,
				      hash_expected,
				      NULL, NULL, skb);
1181 1182 1183

	if (genhash || memcmp(hash_location, newhash, 16) != 0) {
		if (net_ratelimit()) {
1184 1185 1186
			printk(KERN_INFO "MD5 Hash failed for (%pI4, %d)->(%pI4, %d)%s\n",
			       &iph->saddr, ntohs(th->source),
			       &iph->daddr, ntohs(th->dest),
1187 1188 1189 1190 1191 1192 1193 1194 1195
			       genhash ? " tcp_v4_calc_md5_hash failed" : "");
		}
		return 1;
	}
	return 0;
}

#endif

1196
struct request_sock_ops tcp_request_sock_ops __read_mostly = {
L
Linus Torvalds 已提交
1197
	.family		=	PF_INET,
1198
	.obj_size	=	sizeof(struct tcp_request_sock),
1199
	.rtx_syn_ack	=	tcp_v4_rtx_synack,
1200 1201
	.send_ack	=	tcp_v4_reqsk_send_ack,
	.destructor	=	tcp_v4_reqsk_destructor,
L
Linus Torvalds 已提交
1202
	.send_reset	=	tcp_v4_send_reset,
1203
	.syn_ack_timeout = 	tcp_syn_ack_timeout,
L
Linus Torvalds 已提交
1204 1205
};

1206
#ifdef CONFIG_TCP_MD5SIG
1207
static const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
1208
	.md5_lookup	=	tcp_v4_reqsk_md5_lookup,
1209
	.calc_md5_hash	=	tcp_v4_md5_hash_skb,
1210
};
1211
#endif
1212

1213 1214 1215
static struct timewait_sock_ops tcp_timewait_sock_ops = {
	.twsk_obj_size	= sizeof(struct tcp_timewait_sock),
	.twsk_unique	= tcp_twsk_unique,
1216
	.twsk_destructor= tcp_twsk_destructor,
1217 1218
};

L
Linus Torvalds 已提交
1219 1220
int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
{
1221
	struct tcp_extend_values tmp_ext;
L
Linus Torvalds 已提交
1222
	struct tcp_options_received tmp_opt;
1223
	u8 *hash_location;
1224
	struct request_sock *req;
1225
	struct inet_request_sock *ireq;
1226
	struct tcp_sock *tp = tcp_sk(sk);
1227
	struct dst_entry *dst = NULL;
1228 1229
	__be32 saddr = ip_hdr(skb)->saddr;
	__be32 daddr = ip_hdr(skb)->daddr;
L
Linus Torvalds 已提交
1230 1231 1232 1233 1234 1235 1236 1237
	__u32 isn = TCP_SKB_CB(skb)->when;
#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 */
E
Eric Dumazet 已提交
1238
	if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
L
Linus Torvalds 已提交
1239 1240 1241 1242 1243 1244
		goto drop;

	/* TW buckets are converted to open requests without
	 * limitations, they conserve resources and peer is
	 * evidently real one.
	 */
1245
	if (inet_csk_reqsk_queue_is_full(sk) && !isn) {
1246 1247
		if (net_ratelimit())
			syn_flood_warning(skb);
L
Linus Torvalds 已提交
1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260
#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.
	 */
1261
	if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
L
Linus Torvalds 已提交
1262 1263
		goto drop;

1264
	req = inet_reqsk_alloc(&tcp_request_sock_ops);
L
Linus Torvalds 已提交
1265 1266 1267
	if (!req)
		goto drop;

1268 1269 1270 1271
#ifdef CONFIG_TCP_MD5SIG
	tcp_rsk(req)->af_specific = &tcp_request_sock_ipv4_ops;
#endif

L
Linus Torvalds 已提交
1272
	tcp_clear_options(&tmp_opt);
1273
	tmp_opt.mss_clamp = TCP_MSS_DEFAULT;
1274
	tmp_opt.user_mss  = tp->rx_opt.user_mss;
1275
	tcp_parse_options(skb, &tmp_opt, &hash_location, 0);
1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290

	if (tmp_opt.cookie_plus > 0 &&
	    tmp_opt.saw_tstamp &&
	    !tp->rx_opt.cookie_out_never &&
	    (sysctl_tcp_cookie_size > 0 ||
	     (tp->cookie_values != NULL &&
	      tp->cookie_values->cookie_desired > 0))) {
		u8 *c;
		u32 *mess = &tmp_ext.cookie_bakery[COOKIE_DIGEST_WORDS];
		int l = tmp_opt.cookie_plus - TCPOLEN_COOKIE_BASE;

		if (tcp_cookie_generator(&tmp_ext.cookie_bakery[0]) != 0)
			goto drop_and_release;

		/* Secret recipe starts with IP addresses */
1291 1292
		*mess++ ^= (__force u32)daddr;
		*mess++ ^= (__force u32)saddr;
L
Linus Torvalds 已提交
1293

1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311
		/* plus variable length Initiator Cookie */
		c = (u8 *)mess;
		while (l-- > 0)
			*c++ ^= *hash_location++;

#ifdef CONFIG_SYN_COOKIES
		want_cookie = 0;	/* not our kind of cookie */
#endif
		tmp_ext.cookie_out_never = 0; /* false */
		tmp_ext.cookie_plus = tmp_opt.cookie_plus;
	} else if (!tp->rx_opt.cookie_in_always) {
		/* redundant indications, but ensure initialization. */
		tmp_ext.cookie_out_never = 1; /* true */
		tmp_ext.cookie_plus = 0;
	} else {
		goto drop_and_release;
	}
	tmp_ext.cookie_in_always = tp->rx_opt.cookie_in_always;
L
Linus Torvalds 已提交
1312

1313
	if (want_cookie && !tmp_opt.saw_tstamp)
L
Linus Torvalds 已提交
1314 1315 1316 1317 1318
		tcp_clear_options(&tmp_opt);

	tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
	tcp_openreq_init(req, &tmp_opt, skb);

1319 1320 1321 1322 1323 1324
	ireq = inet_rsk(req);
	ireq->loc_addr = daddr;
	ireq->rmt_addr = saddr;
	ireq->no_srccheck = inet_sk(sk)->transparent;
	ireq->opt = tcp_v4_save_options(sk, skb);

1325
	if (security_inet_conn_request(sk, skb, req))
1326
		goto drop_and_free;
1327

1328
	if (!want_cookie || tmp_opt.tstamp_ok)
1329
		TCP_ECN_create_request(req, tcp_hdr(skb));
L
Linus Torvalds 已提交
1330 1331 1332

	if (want_cookie) {
		isn = cookie_v4_init_sequence(sk, skb, &req->mss);
1333
		req->cookie_ts = tmp_opt.tstamp_ok;
L
Linus Torvalds 已提交
1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346
	} 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 &&
1347
		    tcp_death_row.sysctl_tw_recycle &&
1348
		    (dst = inet_csk_route_req(sk, req)) != NULL &&
L
Linus Torvalds 已提交
1349
		    (peer = rt_get_peer((struct rtable *)dst)) != NULL &&
1350
		    peer->daddr.a4 == saddr) {
1351
			inet_peer_refcheck(peer);
E
Eric Dumazet 已提交
1352
			if ((u32)get_seconds() - peer->tcp_ts_stamp < TCP_PAWS_MSL &&
L
Linus Torvalds 已提交
1353 1354
			    (s32)(peer->tcp_ts - req->ts_recent) >
							TCP_PAWS_WINDOW) {
1355
				NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
1356
				goto drop_and_release;
L
Linus Torvalds 已提交
1357 1358 1359 1360
			}
		}
		/* Kill the following clause, if you dislike this way. */
		else if (!sysctl_tcp_syncookies &&
1361
			 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
L
Linus Torvalds 已提交
1362 1363 1364 1365 1366 1367 1368 1369 1370 1371
			  (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.
			 */
1372 1373
			LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open request from %pI4/%u\n",
				       &saddr, ntohs(tcp_hdr(skb)->source));
1374
			goto drop_and_release;
L
Linus Torvalds 已提交
1375 1376
		}

1377
		isn = tcp_v4_init_sequence(skb);
L
Linus Torvalds 已提交
1378
	}
1379
	tcp_rsk(req)->snt_isn = isn;
L
Linus Torvalds 已提交
1380

1381 1382
	if (tcp_v4_send_synack(sk, dst, req,
			       (struct request_values *)&tmp_ext) ||
1383
	    want_cookie)
L
Linus Torvalds 已提交
1384 1385
		goto drop_and_free;

1386
	inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
L
Linus Torvalds 已提交
1387 1388
	return 0;

1389 1390
drop_and_release:
	dst_release(dst);
L
Linus Torvalds 已提交
1391
drop_and_free:
1392
	reqsk_free(req);
L
Linus Torvalds 已提交
1393 1394 1395
drop:
	return 0;
}
E
Eric Dumazet 已提交
1396
EXPORT_SYMBOL(tcp_v4_conn_request);
L
Linus Torvalds 已提交
1397 1398 1399 1400 1401 1402 1403


/*
 * 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,
1404
				  struct request_sock *req,
L
Linus Torvalds 已提交
1405 1406
				  struct dst_entry *dst)
{
1407
	struct inet_request_sock *ireq;
L
Linus Torvalds 已提交
1408 1409 1410
	struct inet_sock *newinet;
	struct tcp_sock *newtp;
	struct sock *newsk;
1411 1412 1413
#ifdef CONFIG_TCP_MD5SIG
	struct tcp_md5sig_key *key;
#endif
L
Linus Torvalds 已提交
1414 1415 1416 1417

	if (sk_acceptq_is_full(sk))
		goto exit_overflow;

1418
	if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
L
Linus Torvalds 已提交
1419 1420 1421 1422
		goto exit;

	newsk = tcp_create_openreq_child(sk, req, skb);
	if (!newsk)
1423
		goto exit_nonewsk;
L
Linus Torvalds 已提交
1424

1425
	newsk->sk_gso_type = SKB_GSO_TCPV4;
1426
	sk_setup_caps(newsk, dst);
L
Linus Torvalds 已提交
1427 1428 1429

	newtp		      = tcp_sk(newsk);
	newinet		      = inet_sk(newsk);
1430
	ireq		      = inet_rsk(req);
E
Eric Dumazet 已提交
1431 1432 1433
	newinet->inet_daddr   = ireq->rmt_addr;
	newinet->inet_rcv_saddr = ireq->loc_addr;
	newinet->inet_saddr	      = ireq->loc_addr;
1434 1435
	newinet->opt	      = ireq->opt;
	ireq->opt	      = NULL;
1436
	newinet->mc_index     = inet_iif(skb);
1437
	newinet->mc_ttl	      = ip_hdr(skb)->ttl;
1438
	inet_csk(newsk)->icsk_ext_hdr_len = 0;
L
Linus Torvalds 已提交
1439
	if (newinet->opt)
1440
		inet_csk(newsk)->icsk_ext_hdr_len = newinet->opt->optlen;
E
Eric Dumazet 已提交
1441
	newinet->inet_id = newtp->write_seq ^ jiffies;
L
Linus Torvalds 已提交
1442

J
John Heffner 已提交
1443
	tcp_mtup_init(newsk);
L
Linus Torvalds 已提交
1444 1445
	tcp_sync_mss(newsk, dst_mtu(dst));
	newtp->advmss = dst_metric(dst, RTAX_ADVMSS);
1446 1447 1448 1449
	if (tcp_sk(sk)->rx_opt.user_mss &&
	    tcp_sk(sk)->rx_opt.user_mss < newtp->advmss)
		newtp->advmss = tcp_sk(sk)->rx_opt.user_mss;

L
Linus Torvalds 已提交
1450 1451
	tcp_initialize_rcv_mss(newsk);

1452 1453
#ifdef CONFIG_TCP_MD5SIG
	/* Copy over the MD5 key from the original socket */
E
Eric Dumazet 已提交
1454 1455
	key = tcp_v4_md5_do_lookup(sk, newinet->inet_daddr);
	if (key != NULL) {
1456 1457 1458 1459 1460 1461
		/*
		 * 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.
		 */
1462 1463
		char *newkey = kmemdup(key->key, key->keylen, GFP_ATOMIC);
		if (newkey != NULL)
E
Eric Dumazet 已提交
1464
			tcp_v4_md5_do_add(newsk, newinet->inet_daddr,
1465
					  newkey, key->keylen);
E
Eric Dumazet 已提交
1466
		sk_nocaps_add(newsk, NETIF_F_GSO_MASK);
1467 1468 1469
	}
#endif

1470 1471 1472 1473
	if (__inet_inherit_port(sk, newsk) < 0) {
		sock_put(newsk);
		goto exit;
	}
1474
	__inet_hash_nolisten(newsk, NULL);
L
Linus Torvalds 已提交
1475 1476 1477 1478

	return newsk;

exit_overflow:
1479
	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
1480 1481
exit_nonewsk:
	dst_release(dst);
L
Linus Torvalds 已提交
1482
exit:
1483
	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
L
Linus Torvalds 已提交
1484 1485
	return NULL;
}
E
Eric Dumazet 已提交
1486
EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
L
Linus Torvalds 已提交
1487 1488 1489

static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
{
1490
	struct tcphdr *th = tcp_hdr(skb);
1491
	const struct iphdr *iph = ip_hdr(skb);
L
Linus Torvalds 已提交
1492
	struct sock *nsk;
1493
	struct request_sock **prev;
L
Linus Torvalds 已提交
1494
	/* Find possible connection requests. */
1495 1496
	struct request_sock *req = inet_csk_search_req(sk, &prev, th->source,
						       iph->saddr, iph->daddr);
L
Linus Torvalds 已提交
1497 1498 1499
	if (req)
		return tcp_check_req(sk, skb, req, prev);

1500
	nsk = inet_lookup_established(sock_net(sk), &tcp_hashinfo, iph->saddr,
1501
			th->source, iph->daddr, th->dest, inet_iif(skb));
L
Linus Torvalds 已提交
1502 1503 1504 1505 1506 1507

	if (nsk) {
		if (nsk->sk_state != TCP_TIME_WAIT) {
			bh_lock_sock(nsk);
			return nsk;
		}
1508
		inet_twsk_put(inet_twsk(nsk));
L
Linus Torvalds 已提交
1509 1510 1511 1512
		return NULL;
	}

#ifdef CONFIG_SYN_COOKIES
1513
	if (!th->syn)
L
Linus Torvalds 已提交
1514 1515 1516 1517 1518
		sk = cookie_v4_check(sk, skb, &(IPCB(skb)->opt));
#endif
	return sk;
}

1519
static __sum16 tcp_v4_checksum_init(struct sk_buff *skb)
L
Linus Torvalds 已提交
1520
{
1521 1522
	const struct iphdr *iph = ip_hdr(skb);

1523
	if (skb->ip_summed == CHECKSUM_COMPLETE) {
1524 1525
		if (!tcp_v4_check(skb->len, iph->saddr,
				  iph->daddr, skb->csum)) {
1526
			skb->ip_summed = CHECKSUM_UNNECESSARY;
L
Linus Torvalds 已提交
1527
			return 0;
1528
		}
L
Linus Torvalds 已提交
1529
	}
1530

1531
	skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
1532 1533
				       skb->len, IPPROTO_TCP, 0);

L
Linus Torvalds 已提交
1534
	if (skb->len <= 76) {
1535
		return __skb_checksum_complete(skb);
L
Linus Torvalds 已提交
1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550
	}
	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)
{
1551 1552 1553 1554 1555 1556 1557 1558
	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
	 */
1559
	if (tcp_v4_inbound_md5_hash(sk, skb))
1560 1561 1562
		goto discard;
#endif

L
Linus Torvalds 已提交
1563
	if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
1564
		sock_rps_save_rxhash(sk, skb->rxhash);
L
Linus Torvalds 已提交
1565
		TCP_CHECK_TIMER(sk);
1566
		if (tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len)) {
1567
			rsk = sk;
L
Linus Torvalds 已提交
1568
			goto reset;
1569
		}
L
Linus Torvalds 已提交
1570 1571 1572 1573
		TCP_CHECK_TIMER(sk);
		return 0;
	}

1574
	if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb))
L
Linus Torvalds 已提交
1575 1576 1577 1578 1579 1580 1581 1582
		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) {
1583 1584
			if (tcp_child_process(sk, nsk, skb)) {
				rsk = nsk;
L
Linus Torvalds 已提交
1585
				goto reset;
1586
			}
L
Linus Torvalds 已提交
1587 1588
			return 0;
		}
1589 1590 1591
	} else
		sock_rps_save_rxhash(sk, skb->rxhash);

L
Linus Torvalds 已提交
1592 1593

	TCP_CHECK_TIMER(sk);
1594
	if (tcp_rcv_state_process(sk, skb, tcp_hdr(skb), skb->len)) {
1595
		rsk = sk;
L
Linus Torvalds 已提交
1596
		goto reset;
1597
	}
L
Linus Torvalds 已提交
1598 1599 1600 1601
	TCP_CHECK_TIMER(sk);
	return 0;

reset:
1602
	tcp_v4_send_reset(rsk, skb);
L
Linus Torvalds 已提交
1603 1604 1605 1606 1607 1608 1609 1610 1611 1612
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:
1613
	TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
L
Linus Torvalds 已提交
1614 1615
	goto discard;
}
E
Eric Dumazet 已提交
1616
EXPORT_SYMBOL(tcp_v4_do_rcv);
L
Linus Torvalds 已提交
1617 1618 1619 1620 1621 1622 1623

/*
 *	From tcp_input.c
 */

int tcp_v4_rcv(struct sk_buff *skb)
{
1624
	const struct iphdr *iph;
L
Linus Torvalds 已提交
1625 1626 1627
	struct tcphdr *th;
	struct sock *sk;
	int ret;
1628
	struct net *net = dev_net(skb->dev);
L
Linus Torvalds 已提交
1629 1630 1631 1632 1633

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

	/* Count it even if it's bad */
1634
	TCP_INC_STATS_BH(net, TCP_MIB_INSEGS);
L
Linus Torvalds 已提交
1635 1636 1637 1638

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

1639
	th = tcp_hdr(skb);
L
Linus Torvalds 已提交
1640 1641 1642 1643 1644 1645 1646 1647

	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
1648
	 * provided case of th->doff==0 is eliminated.
L
Linus Torvalds 已提交
1649
	 * So, we defer the checks. */
1650
	if (!skb_csum_unnecessary(skb) && tcp_v4_checksum_init(skb))
L
Linus Torvalds 已提交
1651 1652
		goto bad_packet;

1653
	th = tcp_hdr(skb);
1654
	iph = ip_hdr(skb);
L
Linus Torvalds 已提交
1655 1656 1657 1658 1659
	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;
1660
	TCP_SKB_CB(skb)->flags	 = iph->tos;
L
Linus Torvalds 已提交
1661 1662
	TCP_SKB_CB(skb)->sacked	 = 0;

1663
	sk = __inet_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest);
L
Linus Torvalds 已提交
1664 1665 1666
	if (!sk)
		goto no_tcp_socket;

E
Eric Dumazet 已提交
1667 1668 1669 1670
process:
	if (sk->sk_state == TCP_TIME_WAIT)
		goto do_time_wait;

1671 1672
	if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) {
		NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
1673
		goto discard_and_relse;
1674
	}
1675

L
Linus Torvalds 已提交
1676 1677
	if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
		goto discard_and_relse;
1678
	nf_reset(skb);
L
Linus Torvalds 已提交
1679

1680
	if (sk_filter(sk, skb))
L
Linus Torvalds 已提交
1681 1682 1683 1684
		goto discard_and_relse;

	skb->dev = NULL;

1685
	bh_lock_sock_nested(sk);
L
Linus Torvalds 已提交
1686 1687
	ret = 0;
	if (!sock_owned_by_user(sk)) {
C
Chris Leech 已提交
1688 1689 1690
#ifdef CONFIG_NET_DMA
		struct tcp_sock *tp = tcp_sk(sk);
		if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1691
			tp->ucopy.dma_chan = dma_find_channel(DMA_MEMCPY);
C
Chris Leech 已提交
1692
		if (tp->ucopy.dma_chan)
L
Linus Torvalds 已提交
1693
			ret = tcp_v4_do_rcv(sk, skb);
C
Chris Leech 已提交
1694 1695 1696 1697
		else
#endif
		{
			if (!tcp_prequeue(sk, skb))
S
Shan Wei 已提交
1698
				ret = tcp_v4_do_rcv(sk, skb);
C
Chris Leech 已提交
1699
		}
1700
	} else if (unlikely(sk_add_backlog(sk, skb))) {
Z
Zhu Yi 已提交
1701
		bh_unlock_sock(sk);
1702
		NET_INC_STATS_BH(net, LINUX_MIB_TCPBACKLOGDROP);
Z
Zhu Yi 已提交
1703 1704
		goto discard_and_relse;
	}
L
Linus Torvalds 已提交
1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716
	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:
1717
		TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
L
Linus Torvalds 已提交
1718
	} else {
1719
		tcp_v4_send_reset(NULL, skb);
L
Linus Torvalds 已提交
1720 1721 1722 1723 1724
	}

discard_it:
	/* Discard frame. */
	kfree_skb(skb);
1725
	return 0;
L
Linus Torvalds 已提交
1726 1727 1728 1729 1730 1731 1732

discard_and_relse:
	sock_put(sk);
	goto discard_it;

do_time_wait:
	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1733
		inet_twsk_put(inet_twsk(sk));
L
Linus Torvalds 已提交
1734 1735 1736 1737
		goto discard_it;
	}

	if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1738
		TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
1739
		inet_twsk_put(inet_twsk(sk));
L
Linus Torvalds 已提交
1740 1741
		goto discard_it;
	}
1742
	switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
L
Linus Torvalds 已提交
1743
	case TCP_TW_SYN: {
1744
		struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev),
1745
							&tcp_hashinfo,
1746
							iph->daddr, th->dest,
1747
							inet_iif(skb));
L
Linus Torvalds 已提交
1748
		if (sk2) {
1749 1750
			inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
			inet_twsk_put(inet_twsk(sk));
L
Linus Torvalds 已提交
1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765
			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;
}

1766
struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it)
L
Linus Torvalds 已提交
1767
{
1768
	struct rtable *rt = (struct rtable *) __sk_dst_get(sk);
L
Linus Torvalds 已提交
1769
	struct inet_sock *inet = inet_sk(sk);
1770
	struct inet_peer *peer;
L
Linus Torvalds 已提交
1771

E
Eric Dumazet 已提交
1772
	if (!rt || rt->rt_dst != inet->inet_daddr) {
1773
		peer = inet_getpeer_v4(inet->inet_daddr, 1);
1774
		*release_it = true;
L
Linus Torvalds 已提交
1775 1776 1777 1778
	} else {
		if (!rt->peer)
			rt_bind_peer(rt, 1);
		peer = rt->peer;
1779
		*release_it = false;
L
Linus Torvalds 已提交
1780 1781
	}

1782
	return peer;
L
Linus Torvalds 已提交
1783
}
1784
EXPORT_SYMBOL(tcp_v4_get_peer);
L
Linus Torvalds 已提交
1785

1786
int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw)
L
Linus Torvalds 已提交
1787
{
1788
	struct inet_peer *peer = inet_getpeer_v4(tw->tw_daddr, 1);
L
Linus Torvalds 已提交
1789 1790

	if (peer) {
1791 1792 1793
		const struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);

		if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 ||
E
Eric Dumazet 已提交
1794 1795 1796
		    ((u32)get_seconds() - peer->tcp_ts_stamp > TCP_PAWS_MSL &&
		     peer->tcp_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) {
			peer->tcp_ts_stamp = (u32)tcptw->tw_ts_recent_stamp;
1797
			peer->tcp_ts	   = tcptw->tw_ts_recent;
L
Linus Torvalds 已提交
1798 1799 1800 1801 1802 1803 1804 1805
		}
		inet_putpeer(peer);
		return 1;
	}

	return 0;
}

1806
const struct inet_connection_sock_af_ops ipv4_specific = {
1807 1808 1809 1810 1811
	.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,
1812
	.get_peer	   = tcp_v4_get_peer,
1813 1814 1815 1816 1817
	.net_header_len	   = sizeof(struct iphdr),
	.setsockopt	   = ip_setsockopt,
	.getsockopt	   = ip_getsockopt,
	.addr2sockaddr	   = inet_csk_addr2sockaddr,
	.sockaddr_len	   = sizeof(struct sockaddr_in),
1818
	.bind_conflict	   = inet_csk_bind_conflict,
1819
#ifdef CONFIG_COMPAT
1820 1821
	.compat_setsockopt = compat_ip_setsockopt,
	.compat_getsockopt = compat_ip_getsockopt,
1822
#endif
L
Linus Torvalds 已提交
1823
};
E
Eric Dumazet 已提交
1824
EXPORT_SYMBOL(ipv4_specific);
L
Linus Torvalds 已提交
1825

1826
#ifdef CONFIG_TCP_MD5SIG
1827
static const struct tcp_sock_af_ops tcp_sock_ipv4_specific = {
1828
	.md5_lookup		= tcp_v4_md5_lookup,
1829
	.calc_md5_hash		= tcp_v4_md5_hash_skb,
1830 1831 1832
	.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
	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.
	 */
I
Ilpo Järvinen 已提交
1860
	tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
L
Linus Torvalds 已提交
1861
	tp->snd_cwnd_clamp = ~0;
1862
	tp->mss_cache = TCP_MSS_DEFAULT;
L
Linus Torvalds 已提交
1863 1864

	tp->reordering = sysctl_tcp_reordering;
1865
	icsk->icsk_ca_ops = &tcp_init_congestion_ops;
L
Linus Torvalds 已提交
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
	/* TCP Cookie Transactions */
	if (sysctl_tcp_cookie_size > 0) {
		/* Default, cookies without s_data_payload. */
		tp->cookie_values =
			kzalloc(sizeof(*tp->cookie_values),
				sk->sk_allocation);
		if (tp->cookie_values != NULL)
			kref_init(&tp->cookie_values->kref);
	}
	/* Presumed zeroed, in order of appearance:
	 *	cookie_in_always, cookie_out_never,
	 *	s_data_constant, s_data_in, s_data_out
	 */
L
Linus Torvalds 已提交
1891 1892 1893
	sk->sk_sndbuf = sysctl_tcp_wmem[1];
	sk->sk_rcvbuf = sysctl_tcp_rmem[1];

H
Herbert Xu 已提交
1894
	local_bh_disable();
1895
	percpu_counter_inc(&tcp_sockets_allocated);
H
Herbert Xu 已提交
1896
	local_bh_enable();
L
Linus Torvalds 已提交
1897 1898 1899 1900

	return 0;
}

1901
void tcp_v4_destroy_sock(struct sock *sk)
L
Linus Torvalds 已提交
1902 1903 1904 1905 1906
{
	struct tcp_sock *tp = tcp_sk(sk);

	tcp_clear_xmit_timers(sk);

1907
	tcp_cleanup_congestion_control(sk);
1908

L
Linus Torvalds 已提交
1909
	/* Cleanup up the write buffer. */
1910
	tcp_write_queue_purge(sk);
L
Linus Torvalds 已提交
1911 1912

	/* Cleans up our, hopefully empty, out_of_order_queue. */
1913
	__skb_queue_purge(&tp->out_of_order_queue);
L
Linus Torvalds 已提交
1914

1915 1916 1917 1918 1919 1920 1921 1922 1923
#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
1924 1925
#ifdef CONFIG_NET_DMA
	/* Cleans up our sk_async_wait_queue */
1926
	__skb_queue_purge(&sk->sk_async_wait_queue);
C
Chris Leech 已提交
1927 1928
#endif

L
Linus Torvalds 已提交
1929 1930 1931 1932
	/* Clean prequeue, it must be empty really */
	__skb_queue_purge(&tp->ucopy.prequeue);

	/* Clean up a referenced TCP bind bucket. */
1933
	if (inet_csk(sk)->icsk_bind_hash)
1934
		inet_put_port(sk);
L
Linus Torvalds 已提交
1935 1936 1937 1938 1939 1940 1941 1942 1943

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

1944 1945 1946 1947 1948 1949 1950
	/* TCP Cookie Transactions */
	if (tp->cookie_values != NULL) {
		kref_put(&tp->cookie_values->kref,
			 tcp_cookie_values_release);
		tp->cookie_values = NULL;
	}

1951
	percpu_counter_dec(&tcp_sockets_allocated);
L
Linus Torvalds 已提交
1952 1953 1954 1955 1956 1957
}
EXPORT_SYMBOL(tcp_v4_destroy_sock);

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

1958
static inline struct inet_timewait_sock *tw_head(struct hlist_nulls_head *head)
L
Linus Torvalds 已提交
1959
{
1960
	return hlist_nulls_empty(head) ? NULL :
1961
		list_entry(head->first, struct inet_timewait_sock, tw_node);
L
Linus Torvalds 已提交
1962 1963
}

1964
static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw)
L
Linus Torvalds 已提交
1965
{
1966 1967
	return !is_a_nulls(tw->tw_node.next) ?
		hlist_nulls_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL;
L
Linus Torvalds 已提交
1968 1969
}

1970 1971 1972 1973 1974
/*
 * Get next listener socket follow cur.  If cur is NULL, get first socket
 * starting from bucket given in st->bucket; when st->bucket is zero the
 * very first socket in the hash table is returned.
 */
L
Linus Torvalds 已提交
1975 1976
static void *listening_get_next(struct seq_file *seq, void *cur)
{
1977
	struct inet_connection_sock *icsk;
1978
	struct hlist_nulls_node *node;
L
Linus Torvalds 已提交
1979
	struct sock *sk = cur;
1980
	struct inet_listen_hashbucket *ilb;
J
Jianjun Kong 已提交
1981
	struct tcp_iter_state *st = seq->private;
1982
	struct net *net = seq_file_net(seq);
L
Linus Torvalds 已提交
1983 1984

	if (!sk) {
1985
		ilb = &tcp_hashinfo.listening_hash[st->bucket];
1986
		spin_lock_bh(&ilb->lock);
1987
		sk = sk_nulls_head(&ilb->head);
1988
		st->offset = 0;
L
Linus Torvalds 已提交
1989 1990
		goto get_sk;
	}
1991
	ilb = &tcp_hashinfo.listening_hash[st->bucket];
L
Linus Torvalds 已提交
1992
	++st->num;
1993
	++st->offset;
L
Linus Torvalds 已提交
1994 1995

	if (st->state == TCP_SEQ_STATE_OPENREQ) {
1996
		struct request_sock *req = cur;
L
Linus Torvalds 已提交
1997

1998
		icsk = inet_csk(st->syn_wait_sk);
L
Linus Torvalds 已提交
1999 2000 2001
		req = req->dl_next;
		while (1) {
			while (req) {
2002
				if (req->rsk_ops->family == st->family) {
L
Linus Torvalds 已提交
2003 2004 2005 2006 2007
					cur = req;
					goto out;
				}
				req = req->dl_next;
			}
2008
			st->offset = 0;
2009
			if (++st->sbucket >= icsk->icsk_accept_queue.listen_opt->nr_table_entries)
L
Linus Torvalds 已提交
2010 2011
				break;
get_req:
2012
			req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];
L
Linus Torvalds 已提交
2013 2014 2015
		}
		sk	  = sk_next(st->syn_wait_sk);
		st->state = TCP_SEQ_STATE_LISTENING;
2016
		read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
L
Linus Torvalds 已提交
2017
	} else {
2018
		icsk = inet_csk(sk);
2019 2020
		read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
		if (reqsk_queue_len(&icsk->icsk_accept_queue))
L
Linus Torvalds 已提交
2021
			goto start_req;
2022
		read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
L
Linus Torvalds 已提交
2023 2024 2025
		sk = sk_next(sk);
	}
get_sk:
2026
	sk_nulls_for_each_from(sk, node) {
2027
		if (sk->sk_family == st->family && net_eq(sock_net(sk), net)) {
L
Linus Torvalds 已提交
2028 2029 2030
			cur = sk;
			goto out;
		}
2031
		icsk = inet_csk(sk);
2032 2033
		read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
		if (reqsk_queue_len(&icsk->icsk_accept_queue)) {
L
Linus Torvalds 已提交
2034 2035 2036 2037 2038 2039 2040
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;
		}
2041
		read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
L
Linus Torvalds 已提交
2042
	}
2043
	spin_unlock_bh(&ilb->lock);
2044
	st->offset = 0;
2045
	if (++st->bucket < INET_LHTABLE_SIZE) {
2046 2047
		ilb = &tcp_hashinfo.listening_hash[st->bucket];
		spin_lock_bh(&ilb->lock);
2048
		sk = sk_nulls_head(&ilb->head);
L
Linus Torvalds 已提交
2049 2050 2051 2052 2053 2054 2055 2056 2057
		goto get_sk;
	}
	cur = NULL;
out:
	return cur;
}

static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
{
2058 2059 2060 2061 2062 2063
	struct tcp_iter_state *st = seq->private;
	void *rc;

	st->bucket = 0;
	st->offset = 0;
	rc = listening_get_next(seq, NULL);
L
Linus Torvalds 已提交
2064 2065 2066 2067 2068 2069 2070 2071

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

2072 2073
static inline int empty_bucket(struct tcp_iter_state *st)
{
2074 2075
	return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain) &&
		hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].twchain);
2076 2077
}

2078 2079 2080 2081
/*
 * Get first established socket starting from bucket given in st->bucket.
 * If st->bucket is zero, the very first socket in the hash is returned.
 */
L
Linus Torvalds 已提交
2082 2083
static void *established_get_first(struct seq_file *seq)
{
J
Jianjun Kong 已提交
2084
	struct tcp_iter_state *st = seq->private;
2085
	struct net *net = seq_file_net(seq);
L
Linus Torvalds 已提交
2086 2087
	void *rc = NULL;

2088 2089
	st->offset = 0;
	for (; st->bucket <= tcp_hashinfo.ehash_mask; ++st->bucket) {
L
Linus Torvalds 已提交
2090
		struct sock *sk;
2091
		struct hlist_nulls_node *node;
2092
		struct inet_timewait_sock *tw;
2093
		spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
L
Linus Torvalds 已提交
2094

2095 2096 2097 2098
		/* Lockless fast path for the common case of empty buckets */
		if (empty_bucket(st))
			continue;

2099
		spin_lock_bh(lock);
2100
		sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
2101
			if (sk->sk_family != st->family ||
2102
			    !net_eq(sock_net(sk), net)) {
L
Linus Torvalds 已提交
2103 2104 2105 2106 2107 2108
				continue;
			}
			rc = sk;
			goto out;
		}
		st->state = TCP_SEQ_STATE_TIME_WAIT;
2109
		inet_twsk_for_each(tw, node,
2110
				   &tcp_hashinfo.ehash[st->bucket].twchain) {
2111
			if (tw->tw_family != st->family ||
2112
			    !net_eq(twsk_net(tw), net)) {
L
Linus Torvalds 已提交
2113 2114 2115 2116 2117
				continue;
			}
			rc = tw;
			goto out;
		}
2118
		spin_unlock_bh(lock);
L
Linus Torvalds 已提交
2119 2120 2121 2122 2123 2124 2125 2126 2127
		st->state = TCP_SEQ_STATE_ESTABLISHED;
	}
out:
	return rc;
}

static void *established_get_next(struct seq_file *seq, void *cur)
{
	struct sock *sk = cur;
2128
	struct inet_timewait_sock *tw;
2129
	struct hlist_nulls_node *node;
J
Jianjun Kong 已提交
2130
	struct tcp_iter_state *st = seq->private;
2131
	struct net *net = seq_file_net(seq);
L
Linus Torvalds 已提交
2132 2133

	++st->num;
2134
	++st->offset;
L
Linus Torvalds 已提交
2135 2136 2137 2138 2139

	if (st->state == TCP_SEQ_STATE_TIME_WAIT) {
		tw = cur;
		tw = tw_next(tw);
get_tw:
2140
		while (tw && (tw->tw_family != st->family || !net_eq(twsk_net(tw), net))) {
L
Linus Torvalds 已提交
2141 2142 2143 2144 2145 2146
			tw = tw_next(tw);
		}
		if (tw) {
			cur = tw;
			goto out;
		}
2147
		spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
L
Linus Torvalds 已提交
2148 2149
		st->state = TCP_SEQ_STATE_ESTABLISHED;

2150
		/* Look for next non empty bucket */
2151
		st->offset = 0;
2152
		while (++st->bucket <= tcp_hashinfo.ehash_mask &&
2153 2154
				empty_bucket(st))
			;
2155
		if (st->bucket > tcp_hashinfo.ehash_mask)
2156 2157
			return NULL;

2158
		spin_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2159
		sk = sk_nulls_head(&tcp_hashinfo.ehash[st->bucket].chain);
L
Linus Torvalds 已提交
2160
	} else
2161
		sk = sk_nulls_next(sk);
L
Linus Torvalds 已提交
2162

2163
	sk_nulls_for_each_from(sk, node) {
2164
		if (sk->sk_family == st->family && net_eq(sock_net(sk), net))
L
Linus Torvalds 已提交
2165 2166 2167 2168
			goto found;
	}

	st->state = TCP_SEQ_STATE_TIME_WAIT;
2169
	tw = tw_head(&tcp_hashinfo.ehash[st->bucket].twchain);
L
Linus Torvalds 已提交
2170 2171 2172 2173 2174 2175 2176 2177 2178
	goto get_tw;
found:
	cur = sk;
out:
	return cur;
}

static void *established_get_idx(struct seq_file *seq, loff_t pos)
{
2179 2180 2181 2182 2183
	struct tcp_iter_state *st = seq->private;
	void *rc;

	st->bucket = 0;
	rc = established_get_first(seq);
L
Linus Torvalds 已提交
2184 2185 2186 2187

	while (rc && pos) {
		rc = established_get_next(seq, rc);
		--pos;
2188
	}
L
Linus Torvalds 已提交
2189 2190 2191 2192 2193 2194
	return rc;
}

static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
{
	void *rc;
J
Jianjun Kong 已提交
2195
	struct tcp_iter_state *st = seq->private;
L
Linus Torvalds 已提交
2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207

	st->state = TCP_SEQ_STATE_LISTENING;
	rc	  = listening_get_idx(seq, &pos);

	if (!rc) {
		st->state = TCP_SEQ_STATE_ESTABLISHED;
		rc	  = established_get_idx(seq, pos);
	}

	return rc;
}

2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242
static void *tcp_seek_last_pos(struct seq_file *seq)
{
	struct tcp_iter_state *st = seq->private;
	int offset = st->offset;
	int orig_num = st->num;
	void *rc = NULL;

	switch (st->state) {
	case TCP_SEQ_STATE_OPENREQ:
	case TCP_SEQ_STATE_LISTENING:
		if (st->bucket >= INET_LHTABLE_SIZE)
			break;
		st->state = TCP_SEQ_STATE_LISTENING;
		rc = listening_get_next(seq, NULL);
		while (offset-- && rc)
			rc = listening_get_next(seq, rc);
		if (rc)
			break;
		st->bucket = 0;
		/* Fallthrough */
	case TCP_SEQ_STATE_ESTABLISHED:
	case TCP_SEQ_STATE_TIME_WAIT:
		st->state = TCP_SEQ_STATE_ESTABLISHED;
		if (st->bucket > tcp_hashinfo.ehash_mask)
			break;
		rc = established_get_first(seq);
		while (offset-- && rc)
			rc = established_get_next(seq, rc);
	}

	st->num = orig_num;

	return rc;
}

L
Linus Torvalds 已提交
2243 2244
static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
{
J
Jianjun Kong 已提交
2245
	struct tcp_iter_state *st = seq->private;
2246 2247 2248 2249 2250 2251 2252 2253
	void *rc;

	if (*pos && *pos == st->last_pos) {
		rc = tcp_seek_last_pos(seq);
		if (rc)
			goto out;
	}

L
Linus Torvalds 已提交
2254 2255
	st->state = TCP_SEQ_STATE_LISTENING;
	st->num = 0;
2256 2257 2258 2259 2260 2261 2262
	st->bucket = 0;
	st->offset = 0;
	rc = *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;

out:
	st->last_pos = *pos;
	return rc;
L
Linus Torvalds 已提交
2263 2264 2265 2266
}

static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
2267
	struct tcp_iter_state *st = seq->private;
L
Linus Torvalds 已提交
2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280
	void *rc = NULL;

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

	switch (st->state) {
	case TCP_SEQ_STATE_OPENREQ:
	case TCP_SEQ_STATE_LISTENING:
		rc = listening_get_next(seq, v);
		if (!rc) {
			st->state = TCP_SEQ_STATE_ESTABLISHED;
2281 2282
			st->bucket = 0;
			st->offset = 0;
L
Linus Torvalds 已提交
2283 2284 2285 2286 2287 2288 2289 2290 2291 2292
			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;
2293
	st->last_pos = *pos;
L
Linus Torvalds 已提交
2294 2295 2296 2297 2298
	return rc;
}

static void tcp_seq_stop(struct seq_file *seq, void *v)
{
J
Jianjun Kong 已提交
2299
	struct tcp_iter_state *st = seq->private;
L
Linus Torvalds 已提交
2300 2301 2302 2303

	switch (st->state) {
	case TCP_SEQ_STATE_OPENREQ:
		if (v) {
2304 2305
			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
2306 2307 2308
		}
	case TCP_SEQ_STATE_LISTENING:
		if (v != SEQ_START_TOKEN)
2309
			spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock);
L
Linus Torvalds 已提交
2310 2311 2312 2313
		break;
	case TCP_SEQ_STATE_TIME_WAIT:
	case TCP_SEQ_STATE_ESTABLISHED:
		if (v)
2314
			spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
L
Linus Torvalds 已提交
2315 2316 2317 2318 2319 2320 2321 2322
		break;
	}
}

static int tcp_seq_open(struct inode *inode, struct file *file)
{
	struct tcp_seq_afinfo *afinfo = PDE(inode)->data;
	struct tcp_iter_state *s;
2323
	int err;
L
Linus Torvalds 已提交
2324

2325 2326 2327 2328
	err = seq_open_net(inode, file, &afinfo->seq_ops,
			  sizeof(struct tcp_iter_state));
	if (err < 0)
		return err;
2329

2330
	s = ((struct seq_file *)file->private_data)->private;
L
Linus Torvalds 已提交
2331
	s->family		= afinfo->family;
2332
	s->last_pos 		= 0;
2333 2334 2335
	return 0;
}

2336
int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo)
L
Linus Torvalds 已提交
2337 2338 2339 2340
{
	int rc = 0;
	struct proc_dir_entry *p;

2341 2342 2343 2344
	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_net;
2345

2346 2347 2348 2349
	afinfo->seq_ops.start		= tcp_seq_start;
	afinfo->seq_ops.next		= tcp_seq_next;
	afinfo->seq_ops.stop		= tcp_seq_stop;

2350 2351 2352
	p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net,
			     &afinfo->seq_fops, afinfo);
	if (!p)
L
Linus Torvalds 已提交
2353 2354 2355
		rc = -ENOMEM;
	return rc;
}
E
Eric Dumazet 已提交
2356
EXPORT_SYMBOL(tcp_proc_register);
L
Linus Torvalds 已提交
2357

2358
void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo)
L
Linus Torvalds 已提交
2359
{
2360
	proc_net_remove(net, afinfo->name);
L
Linus Torvalds 已提交
2361
}
E
Eric Dumazet 已提交
2362
EXPORT_SYMBOL(tcp_proc_unregister);
L
Linus Torvalds 已提交
2363

2364
static void get_openreq4(struct sock *sk, struct request_sock *req,
2365
			 struct seq_file *f, int i, int uid, int *len)
L
Linus Torvalds 已提交
2366
{
2367
	const struct inet_request_sock *ireq = inet_rsk(req);
L
Linus Torvalds 已提交
2368 2369
	int ttd = req->expires - jiffies;

2370 2371
	seq_printf(f, "%4d: %08X:%04X %08X:%04X"
		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %p%n",
L
Linus Torvalds 已提交
2372
		i,
2373
		ireq->loc_addr,
E
Eric Dumazet 已提交
2374
		ntohs(inet_sk(sk)->inet_sport),
2375 2376
		ireq->rmt_addr,
		ntohs(ireq->rmt_port),
L
Linus Torvalds 已提交
2377 2378 2379 2380 2381 2382 2383 2384 2385
		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),
2386 2387
		req,
		len);
L
Linus Torvalds 已提交
2388 2389
}

2390
static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
L
Linus Torvalds 已提交
2391 2392 2393
{
	int timer_active;
	unsigned long timer_expires;
2394 2395 2396
	struct tcp_sock *tp = tcp_sk(sk);
	const struct inet_connection_sock *icsk = inet_csk(sk);
	struct inet_sock *inet = inet_sk(sk);
E
Eric Dumazet 已提交
2397 2398 2399 2400
	__be32 dest = inet->inet_daddr;
	__be32 src = inet->inet_rcv_saddr;
	__u16 destp = ntohs(inet->inet_dport);
	__u16 srcp = ntohs(inet->inet_sport);
2401
	int rx_queue;
L
Linus Torvalds 已提交
2402

2403
	if (icsk->icsk_pending == ICSK_TIME_RETRANS) {
L
Linus Torvalds 已提交
2404
		timer_active	= 1;
2405 2406
		timer_expires	= icsk->icsk_timeout;
	} else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
L
Linus Torvalds 已提交
2407
		timer_active	= 4;
2408
		timer_expires	= icsk->icsk_timeout;
2409
	} else if (timer_pending(&sk->sk_timer)) {
L
Linus Torvalds 已提交
2410
		timer_active	= 2;
2411
		timer_expires	= sk->sk_timer.expires;
L
Linus Torvalds 已提交
2412 2413 2414 2415 2416
	} else {
		timer_active	= 0;
		timer_expires = jiffies;
	}

2417 2418 2419 2420 2421 2422 2423 2424
	if (sk->sk_state == TCP_LISTEN)
		rx_queue = sk->sk_ack_backlog;
	else
		/*
		 * because we dont lock socket, we might find a transient negative value
		 */
		rx_queue = max_t(int, tp->rcv_nxt - tp->copied_seq, 0);

2425
	seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
2426
			"%08X %5d %8d %lu %d %p %lu %lu %u %u %d%n",
2427
		i, src, srcp, dest, destp, sk->sk_state,
2428
		tp->write_seq - tp->snd_una,
2429
		rx_queue,
L
Linus Torvalds 已提交
2430 2431
		timer_active,
		jiffies_to_clock_t(timer_expires - jiffies),
2432
		icsk->icsk_retransmits,
2433
		sock_i_uid(sk),
2434
		icsk->icsk_probes_out,
2435 2436
		sock_i_ino(sk),
		atomic_read(&sk->sk_refcnt), sk,
2437 2438
		jiffies_to_clock_t(icsk->icsk_rto),
		jiffies_to_clock_t(icsk->icsk_ack.ato),
2439
		(icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
L
Linus Torvalds 已提交
2440
		tp->snd_cwnd,
I
Ilpo Järvinen 已提交
2441
		tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh,
2442
		len);
L
Linus Torvalds 已提交
2443 2444
}

2445
static void get_timewait4_sock(struct inet_timewait_sock *tw,
2446
			       struct seq_file *f, int i, int *len)
L
Linus Torvalds 已提交
2447
{
2448
	__be32 dest, src;
L
Linus Torvalds 已提交
2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459
	__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);

2460 2461
	seq_printf(f, "%4d: %08X:%04X %08X:%04X"
		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %p%n",
L
Linus Torvalds 已提交
2462 2463
		i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
		3, jiffies_to_clock_t(ttd), 0, 0, 0, 0,
2464
		atomic_read(&tw->tw_refcnt), tw, len);
L
Linus Torvalds 已提交
2465 2466 2467 2468 2469 2470
}

#define TMPSZ 150

static int tcp4_seq_show(struct seq_file *seq, void *v)
{
J
Jianjun Kong 已提交
2471
	struct tcp_iter_state *st;
2472
	int len;
L
Linus Torvalds 已提交
2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485

	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:
2486
		get_tcp4_sock(v, seq, st->num, &len);
L
Linus Torvalds 已提交
2487 2488
		break;
	case TCP_SEQ_STATE_OPENREQ:
2489
		get_openreq4(st->syn_wait_sk, v, seq, st->num, st->uid, &len);
L
Linus Torvalds 已提交
2490 2491
		break;
	case TCP_SEQ_STATE_TIME_WAIT:
2492
		get_timewait4_sock(v, seq, st->num, &len);
L
Linus Torvalds 已提交
2493 2494
		break;
	}
2495
	seq_printf(seq, "%*s\n", TMPSZ - 1 - len, "");
L
Linus Torvalds 已提交
2496 2497 2498 2499 2500 2501 2502
out:
	return 0;
}

static struct tcp_seq_afinfo tcp4_seq_afinfo = {
	.name		= "tcp",
	.family		= AF_INET,
2503 2504 2505
	.seq_fops	= {
		.owner		= THIS_MODULE,
	},
2506 2507 2508
	.seq_ops	= {
		.show		= tcp4_seq_show,
	},
L
Linus Torvalds 已提交
2509 2510
};

2511
static int __net_init tcp4_proc_init_net(struct net *net)
2512 2513 2514 2515
{
	return tcp_proc_register(net, &tcp4_seq_afinfo);
}

2516
static void __net_exit tcp4_proc_exit_net(struct net *net)
2517 2518 2519 2520 2521 2522 2523 2524 2525
{
	tcp_proc_unregister(net, &tcp4_seq_afinfo);
}

static struct pernet_operations tcp4_net_ops = {
	.init = tcp4_proc_init_net,
	.exit = tcp4_proc_exit_net,
};

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int __init tcp4_proc_init(void)
{
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	return register_pernet_subsys(&tcp4_net_ops);
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}

void tcp4_proc_exit(void)
{
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	unregister_pernet_subsys(&tcp4_net_ops);
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}
#endif /* CONFIG_PROC_FS */

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struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb)
{
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	struct iphdr *iph = skb_gro_network_header(skb);
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	switch (skb->ip_summed) {
	case CHECKSUM_COMPLETE:
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		if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr,
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				  skb->csum)) {
			skb->ip_summed = CHECKSUM_UNNECESSARY;
			break;
		}

		/* fall through */
	case CHECKSUM_NONE:
		NAPI_GRO_CB(skb)->flush = 1;
		return NULL;
	}

	return tcp_gro_receive(head, skb);
}

int tcp4_gro_complete(struct sk_buff *skb)
{
	struct iphdr *iph = ip_hdr(skb);
	struct tcphdr *th = tcp_hdr(skb);

	th->check = ~tcp_v4_check(skb->len - skb_transport_offset(skb),
				  iph->saddr, iph->daddr, 0);
	skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;

	return tcp_gro_complete(skb);
}

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struct proto tcp_prot = {
	.name			= "TCP",
	.owner			= THIS_MODULE,
	.close			= tcp_close,
	.connect		= tcp_v4_connect,
	.disconnect		= tcp_disconnect,
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	.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,
	.recvmsg		= tcp_recvmsg,
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	.sendmsg		= tcp_sendmsg,
	.sendpage		= tcp_sendpage,
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	.backlog_rcv		= tcp_v4_do_rcv,
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	.hash			= inet_hash,
	.unhash			= inet_unhash,
	.get_port		= inet_csk_get_port,
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	.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),
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	.slab_flags		= SLAB_DESTROY_BY_RCU,
2601
	.twsk_prot		= &tcp_timewait_sock_ops,
2602
	.rsk_prot		= &tcp_request_sock_ops,
2603
	.h.hashinfo		= &tcp_hashinfo,
2604
	.no_autobind		= true,
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#ifdef CONFIG_COMPAT
	.compat_setsockopt	= compat_tcp_setsockopt,
	.compat_getsockopt	= compat_tcp_getsockopt,
#endif
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};
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EXPORT_SYMBOL(tcp_prot);
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static int __net_init tcp_sk_init(struct net *net)
{
	return inet_ctl_sock_create(&net->ipv4.tcp_sock,
				    PF_INET, SOCK_RAW, IPPROTO_TCP, net);
}

static void __net_exit tcp_sk_exit(struct net *net)
{
	inet_ctl_sock_destroy(net->ipv4.tcp_sock);
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}

static void __net_exit tcp_sk_exit_batch(struct list_head *net_exit_list)
{
	inet_twsk_purge(&tcp_hashinfo, &tcp_death_row, AF_INET);
2627 2628 2629
}

static struct pernet_operations __net_initdata tcp_sk_ops = {
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       .init	   = tcp_sk_init,
       .exit	   = tcp_sk_exit,
       .exit_batch = tcp_sk_exit_batch,
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};

2635
void __init tcp_v4_init(void)
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{
2637
	inet_hashinfo_init(&tcp_hashinfo);
2638
	if (register_pernet_subsys(&tcp_sk_ops))
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		panic("Failed to create the TCP control socket.\n");
}