/* Returns verdict for packet, or -1 for invalid. */
static int tcp_packet(struct ip_conntrack *conntrack,
		      struct iphdr *iph, size_t len,
		      enum ip_conntrack_info ctinfo)
{
	enum tcp_conntrack newconntrack, oldtcpstate;
	struct tcphdr *tcph = (struct tcphdr *)((u_int32_t *)iph + iph->ihl);

	/* We're guaranteed to have the base header, but maybe not the
           options. */
	if (len < (iph->ihl + tcph->doff) * 4) {
		DEBUGP("ip_conntrack_tcp: Truncated packet.\n");
		return -1;
	}

	WRITE_LOCK(&tcp_lock);
	oldtcpstate = conntrack->proto.tcp.state;
	newconntrack
		= tcp_conntracks
		[CTINFO2DIR(ctinfo)]
		[get_conntrack_index(tcph)][oldtcpstate];

	/* Invalid */
	if (newconntrack == TCP_CONNTRACK_MAX) {
		DEBUGP("ip_conntrack_tcp: Invalid dir=%i index=%u conntrack=%u\n",
		       CTINFO2DIR(ctinfo), get_conntrack_index(tcph),
		       conntrack->proto.tcp.state);
		WRITE_UNLOCK(&tcp_lock);
		return -1;
	}

	conntrack->proto.tcp.state = newconntrack;

	/* Poor man's window tracking: record SYN/ACK for handshake check */
	if (oldtcpstate == TCP_CONNTRACK_SYN_SENT
	    && CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY
	    && tcph->syn && tcph->ack)
		conntrack->proto.tcp.handshake_ack
			= htonl(ntohl(tcph->seq) + 1);
	WRITE_UNLOCK(&tcp_lock);

	/* If only reply is a RST, we can consider ourselves not to
	   have an established connection: this is a fairly common
	   problem case, so we can delete the conntrack
	   immediately.  --RR */
	if (!(conntrack->status & IPS_SEEN_REPLY) && tcph->rst) {
		if (del_timer(&conntrack->timeout))
			conntrack->timeout.function((unsigned long)conntrack);
	} else {
		/* Set ASSURED if we see see valid ack in ESTABLISHED after SYN_RECV */
		if (oldtcpstate == TCP_CONNTRACK_SYN_RECV
		    && CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL
		    && tcph->ack && !tcph->syn
		    && tcph->ack_seq == conntrack->proto.tcp.handshake_ack)
			set_bit(IPS_ASSURED_BIT, &conntrack->status);

		ip_ct_refresh(conntrack, tcp_timeouts[newconntrack]);
	}

	return NF_ACCEPT;
}
Exemple #2
0
static int update_state(const void *pkt, struct tn_ctrack *ct, 
			int dir, int idx)
{
    struct tcphdr *tcp = (struct tcphdr *)pkt;

    ct->state[idx] = tcp_conntracks[(dir == ct->dir) ? 0 : 1]
	[get_conntrack_index(tcp)][ct->state[idx]];

    return tcp_timeouts[ct->state[idx]];
}
/* Called when a new connection for this protocol found. */
static int tcp_new(struct ip_conntrack *conntrack,
		   struct iphdr *iph, size_t len)
{
	enum tcp_conntrack newconntrack;
	struct tcphdr *tcph = (struct tcphdr *)((u_int32_t *)iph + iph->ihl);

	/* Don't need lock here: this conntrack not in circulation yet */
	newconntrack
		= tcp_conntracks[0][get_conntrack_index(tcph)]
		[TCP_CONNTRACK_NONE];

	/* Invalid: delete conntrack */
	if (newconntrack == TCP_CONNTRACK_MAX) {
		DEBUGP("ip_conntrack_tcp: invalid new deleting.\n");
		return 0;
	}

	conntrack->proto.tcp.state = newconntrack;
	return 1;
}
/* Called when a new connection for this protocol found. */
static int tcp_new(struct ip_conntrack *conntrack, const struct sk_buff *skb)
{
	enum tcp_conntrack newconntrack;
	struct tcphdr tcph;

	if (skb_copy_bits(skb, skb->nh.iph->ihl * 4, &tcph, sizeof(tcph)) != 0)
		return -1;

	/* Don't need lock here: this conntrack not in circulation yet */
	newconntrack
		= tcp_conntracks[0][get_conntrack_index(&tcph)]
		[TCP_CONNTRACK_NONE];

	/* Invalid: delete conntrack */
	if (newconntrack == TCP_CONNTRACK_MAX) {
		DEBUGP("ip_conntrack_tcp: invalid new deleting.\n");
		return 0;
	}

	conntrack->proto.tcp.state = newconntrack;
	return 1;
}
/* Returns verdict for packet, or -1 for invalid. */
static int tcp_packet(struct nf_conn *ct,
		      const struct sk_buff *skb,
		      unsigned int dataoff,
		      enum ip_conntrack_info ctinfo,
		      u_int8_t pf,
		      unsigned int hooknum)
{
	struct net *net = nf_ct_net(ct);
	struct nf_conntrack_tuple *tuple;
#if defined(CONFIG_MV_ETH_NFP_CT_LEARN)
	struct nf_conntrack_tuple *tupleInverseDir;
#endif
	enum tcp_conntrack new_state, old_state;
	enum ip_conntrack_dir dir;
	const struct tcphdr *th;
	struct tcphdr _tcph;
	unsigned long timeout;
	unsigned int index;

	th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
	BUG_ON(th == NULL);

	spin_lock_bh(&ct->lock);
	old_state = ct->proto.tcp.state;
	dir = CTINFO2DIR(ctinfo);
	index = get_conntrack_index(th);
	new_state = tcp_conntracks[dir][index][old_state];
	tuple = &ct->tuplehash[dir].tuple;
#if defined(CONFIG_MV_ETH_NFP_CT_LEARN)
	tupleInverseDir	= &ct->tuplehash[!dir].tuple;
#endif
	switch (new_state) {
	case TCP_CONNTRACK_SYN_SENT:
		if (old_state < TCP_CONNTRACK_TIME_WAIT)
			break;
		/* RFC 1122: "When a connection is closed actively,
		 * it MUST linger in TIME-WAIT state for a time 2xMSL
		 * (Maximum Segment Lifetime). However, it MAY accept
		 * a new SYN from the remote TCP to reopen the connection
		 * directly from TIME-WAIT state, if..."
		 * We ignore the conditions because we are in the
		 * TIME-WAIT state anyway.
		 *
		 * Handle aborted connections: we and the server
		 * think there is an existing connection but the client
		 * aborts it and starts a new one.
		 */
		if (((ct->proto.tcp.seen[dir].flags
		      | ct->proto.tcp.seen[!dir].flags)
		     & IP_CT_TCP_FLAG_CLOSE_INIT)
		    || (ct->proto.tcp.last_dir == dir
		        && ct->proto.tcp.last_index == TCP_RST_SET)) {
			/* Attempt to reopen a closed/aborted connection.
			 * Delete this connection and look up again. */
			spin_unlock_bh(&ct->lock);

			/* Only repeat if we can actually remove the timer.
			 * Destruction may already be in progress in process
			 * context and we must give it a chance to terminate.
			 */
			if (nf_ct_kill(ct))
				return -NF_REPEAT;
			return NF_DROP;
		}
		/* Fall through */
	case TCP_CONNTRACK_IGNORE:
		/* Ignored packets:
		 *
		 * Our connection entry may be out of sync, so ignore
		 * packets which may signal the real connection between
		 * the client and the server.
		 *
		 * a) SYN in ORIGINAL
		 * b) SYN/ACK in REPLY
		 * c) ACK in reply direction after initial SYN in original.
		 *
		 * If the ignored packet is invalid, the receiver will send
		 * a RST we'll catch below.
		 */
		if (index == TCP_SYNACK_SET
		    && ct->proto.tcp.last_index == TCP_SYN_SET
		    && ct->proto.tcp.last_dir != dir
		    && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
			/* b) This SYN/ACK acknowledges a SYN that we earlier
			 * ignored as invalid. This means that the client and
			 * the server are both in sync, while the firewall is
			 * not. We kill this session and block the SYN/ACK so
			 * that the client cannot but retransmit its SYN and
			 * thus initiate a clean new session.
			 */
			spin_unlock_bh(&ct->lock);
			if (LOG_INVALID(net, IPPROTO_TCP))
				nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
					  "nf_ct_tcp: killing out of sync session ");
			nf_ct_kill(ct);
			return NF_DROP;
		}
		ct->proto.tcp.last_index = index;
		ct->proto.tcp.last_dir = dir;
		ct->proto.tcp.last_seq = ntohl(th->seq);
		ct->proto.tcp.last_end =
		    segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);

		spin_unlock_bh(&ct->lock);
		if (LOG_INVALID(net, IPPROTO_TCP))
			nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
				  "nf_ct_tcp: invalid packet ignored ");
		return NF_ACCEPT;
	case TCP_CONNTRACK_MAX:
		/* Invalid packet */
		pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
			 dir, get_conntrack_index(th), old_state);
		spin_unlock_bh(&ct->lock);
		if (LOG_INVALID(net, IPPROTO_TCP))
			nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
				  "nf_ct_tcp: invalid state ");
		return -NF_ACCEPT;
	case TCP_CONNTRACK_CLOSE:
		if (index == TCP_RST_SET
		    && (ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET)
		    && before(ntohl(th->seq), ct->proto.tcp.seen[!dir].td_maxack)) {
			/* Invalid RST  */
			spin_unlock_bh(&ct->lock);
			if (LOG_INVALID(net, IPPROTO_TCP))
				nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
					  "nf_ct_tcp: invalid RST ");
			return -NF_ACCEPT;
		}
		if (index == TCP_RST_SET
		    && ((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
			 && ct->proto.tcp.last_index == TCP_SYN_SET)
			|| (!test_bit(IPS_ASSURED_BIT, &ct->status)
			    && ct->proto.tcp.last_index == TCP_ACK_SET))
		    && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
			/* RST sent to invalid SYN or ACK we had let through
			 * at a) and c) above:
			 *
			 * a) SYN was in window then
			 * c) we hold a half-open connection.
			 *
			 * Delete our connection entry.
			 * We skip window checking, because packet might ACK
			 * segments we ignored. */
			goto in_window;
		}
		/* Just fall through */
	default:
		/* Keep compilers happy. */
		break;
	}

#if defined(CONFIG_MV_ETH_NFP_CT_LEARN)
	/*
	 * When connection is handled by NFP, we have to relax TCP tracking
	 * rules as not all packets goes through Linux conntrack.
	 */
	if ((tuple->nfp) || (tupleInverseDir->nfp))
		goto in_window;
#endif /* CONFIG_MV_ETH_NFP_CT_LEARN */

	if (!tcp_in_window(ct, &ct->proto.tcp, dir, index,
			   skb, dataoff, th, pf)) {
		spin_unlock_bh(&ct->lock);
		return -NF_ACCEPT;
	}
     in_window:
	/* From now on we have got in-window packets */
	ct->proto.tcp.last_index = index;
	ct->proto.tcp.last_dir = dir;

	pr_debug("tcp_conntracks: ");
	nf_ct_dump_tuple(tuple);
	pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
		 (th->syn ? 1 : 0), (th->ack ? 1 : 0),
		 (th->fin ? 1 : 0), (th->rst ? 1 : 0),
		 old_state, new_state);

	ct->proto.tcp.state = new_state;
	if (old_state != new_state
	    && new_state == TCP_CONNTRACK_FIN_WAIT)
		ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;

	if (ct->proto.tcp.retrans >= nf_ct_tcp_max_retrans &&
	    tcp_timeouts[new_state] > nf_ct_tcp_timeout_max_retrans)
		timeout = nf_ct_tcp_timeout_max_retrans;
	else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
		 IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
		 tcp_timeouts[new_state] > nf_ct_tcp_timeout_unacknowledged)
		timeout = nf_ct_tcp_timeout_unacknowledged;
	else
		timeout = tcp_timeouts[new_state];
	spin_unlock_bh(&ct->lock);

	if (new_state != old_state)
		nf_conntrack_event_cache(IPCT_PROTOINFO, ct);

	if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
		/* If only reply is a RST, we can consider ourselves not to
		   have an established connection: this is a fairly common
		   problem case, so we can delete the conntrack
		   immediately.  --RR */
		if (th->rst) {
			nf_ct_kill_acct(ct, ctinfo, skb);
			return NF_ACCEPT;
		}
	} else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
		   && (old_state == TCP_CONNTRACK_SYN_RECV
		       || old_state == TCP_CONNTRACK_ESTABLISHED)
		   && new_state == TCP_CONNTRACK_ESTABLISHED) {
		/* Set ASSURED if we see see valid ack in ESTABLISHED
		   after SYN_RECV or a valid answer for a picked up
		   connection. */
		set_bit(IPS_ASSURED_BIT, &ct->status);
		nf_conntrack_event_cache(IPCT_STATUS, ct);
	}
	nf_ct_refresh_acct(ct, ctinfo, skb, timeout);

	return NF_ACCEPT;
}
/* Called when a new connection for this protocol found. */
static bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb,
		    unsigned int dataoff)
{
	enum tcp_conntrack new_state;
	const struct tcphdr *th;
	struct tcphdr _tcph;
	const struct ip_ct_tcp_state *sender = &ct->proto.tcp.seen[0];
	const struct ip_ct_tcp_state *receiver = &ct->proto.tcp.seen[1];

	th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
	BUG_ON(th == NULL);

	/* Don't need lock here: this conntrack not in circulation yet */
	new_state
		= tcp_conntracks[0][get_conntrack_index(th)]
		[TCP_CONNTRACK_NONE];

	/* Invalid: delete conntrack */
	if (new_state >= TCP_CONNTRACK_MAX) {
		pr_debug("nf_ct_tcp: invalid new deleting.\n");
		return false;
	}

	if (new_state == TCP_CONNTRACK_SYN_SENT) {
		/* SYN packet */
		ct->proto.tcp.seen[0].td_end =
			segment_seq_plus_len(ntohl(th->seq), skb->len,
					     dataoff, th);
		ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
		if (ct->proto.tcp.seen[0].td_maxwin == 0)
			ct->proto.tcp.seen[0].td_maxwin = 1;
		ct->proto.tcp.seen[0].td_maxend =
			ct->proto.tcp.seen[0].td_end;

		tcp_options(skb, dataoff, th, &ct->proto.tcp.seen[0]);
		ct->proto.tcp.seen[1].flags = 0;
	} else if (nf_ct_tcp_loose == 0) {
		/* Don't try to pick up connections. */
		return false;
	} else {
		/*
		 * We are in the middle of a connection,
		 * its history is lost for us.
		 * Let's try to use the data from the packet.
		 */
		ct->proto.tcp.seen[0].td_end =
			segment_seq_plus_len(ntohl(th->seq), skb->len,
					     dataoff, th);
		ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
		if (ct->proto.tcp.seen[0].td_maxwin == 0)
			ct->proto.tcp.seen[0].td_maxwin = 1;
		ct->proto.tcp.seen[0].td_maxend =
			ct->proto.tcp.seen[0].td_end +
			ct->proto.tcp.seen[0].td_maxwin;
		ct->proto.tcp.seen[0].td_scale = 0;

		/* We assume SACK and liberal window checking to handle
		 * window scaling */
		ct->proto.tcp.seen[0].flags =
		ct->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
					      IP_CT_TCP_FLAG_BE_LIBERAL;
	}

	ct->proto.tcp.seen[1].td_end = 0;
	ct->proto.tcp.seen[1].td_maxend = 0;
	ct->proto.tcp.seen[1].td_maxwin = 0;
	ct->proto.tcp.seen[1].td_scale = 0;

	/* tcp_packet will set them */
	ct->proto.tcp.state = TCP_CONNTRACK_NONE;
	ct->proto.tcp.last_index = TCP_NONE_SET;

	pr_debug("tcp_new: sender end=%u maxend=%u maxwin=%u scale=%i "
		 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
		 sender->td_end, sender->td_maxend, sender->td_maxwin,
		 sender->td_scale,
		 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
		 receiver->td_scale);
	return true;
}
static bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb,
		    unsigned int dataoff, unsigned int *timeouts)
{
	enum tcp_conntrack new_state;
	const struct tcphdr *th;
	struct tcphdr _tcph;
	const struct ip_ct_tcp_state *sender = &ct->proto.tcp.seen[0];
	const struct ip_ct_tcp_state *receiver = &ct->proto.tcp.seen[1];

	th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
	BUG_ON(th == NULL);

	
	new_state = tcp_conntracks[0][get_conntrack_index(th)][TCP_CONNTRACK_NONE];

	
	if (new_state >= TCP_CONNTRACK_MAX) {
		pr_debug("nf_ct_tcp: invalid new deleting.\n");
		return false;
	}

	if (new_state == TCP_CONNTRACK_SYN_SENT) {
		memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
		
		ct->proto.tcp.seen[0].td_end =
			segment_seq_plus_len(ntohl(th->seq), skb->len,
					     dataoff, th);
		ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
		if (ct->proto.tcp.seen[0].td_maxwin == 0)
			ct->proto.tcp.seen[0].td_maxwin = 1;
		ct->proto.tcp.seen[0].td_maxend =
			ct->proto.tcp.seen[0].td_end;

		tcp_options(skb, dataoff, th, &ct->proto.tcp.seen[0]);
	} else if (nf_ct_tcp_loose == 0) {
		
		return false;
	} else {
		memset(&ct->proto.tcp, 0, sizeof(ct->proto.tcp));
		ct->proto.tcp.seen[0].td_end =
			segment_seq_plus_len(ntohl(th->seq), skb->len,
					     dataoff, th);
		ct->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
		if (ct->proto.tcp.seen[0].td_maxwin == 0)
			ct->proto.tcp.seen[0].td_maxwin = 1;
		ct->proto.tcp.seen[0].td_maxend =
			ct->proto.tcp.seen[0].td_end +
			ct->proto.tcp.seen[0].td_maxwin;

		ct->proto.tcp.seen[0].flags =
		ct->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM |
					      IP_CT_TCP_FLAG_BE_LIBERAL;
	}

	
	ct->proto.tcp.last_index = TCP_NONE_SET;

	pr_debug("tcp_new: sender end=%u maxend=%u maxwin=%u scale=%i "
		 "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
		 sender->td_end, sender->td_maxend, sender->td_maxwin,
		 sender->td_scale,
		 receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
		 receiver->td_scale);
	return true;
}
static int tcp_packet(struct nf_conn *ct,
		      const struct sk_buff *skb,
		      unsigned int dataoff,
		      enum ip_conntrack_info ctinfo,
		      u_int8_t pf,
		      unsigned int hooknum,
		      unsigned int *timeouts)
{
	struct net *net = nf_ct_net(ct);
	struct nf_conntrack_tuple *tuple;
	enum tcp_conntrack new_state, old_state;
	enum ip_conntrack_dir dir;
	const struct tcphdr *th;
	struct tcphdr _tcph;
	unsigned long timeout;
	unsigned int index;

	th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
	BUG_ON(th == NULL);

	spin_lock_bh(&ct->lock);
	old_state = ct->proto.tcp.state;
	dir = CTINFO2DIR(ctinfo);
	index = get_conntrack_index(th);
	new_state = tcp_conntracks[dir][index][old_state];
	tuple = &ct->tuplehash[dir].tuple;

	switch (new_state) {
	case TCP_CONNTRACK_SYN_SENT:
		if (old_state < TCP_CONNTRACK_TIME_WAIT)
			break;
		if (((ct->proto.tcp.seen[dir].flags
		      | ct->proto.tcp.seen[!dir].flags)
		     & IP_CT_TCP_FLAG_CLOSE_INIT)
		    || (ct->proto.tcp.last_dir == dir
		        && ct->proto.tcp.last_index == TCP_RST_SET)) {
			spin_unlock_bh(&ct->lock);

			if (nf_ct_kill(ct))
				return -NF_REPEAT;
			return NF_DROP;
		}
		
	case TCP_CONNTRACK_IGNORE:
		if (index == TCP_SYNACK_SET
		    && ct->proto.tcp.last_index == TCP_SYN_SET
		    && ct->proto.tcp.last_dir != dir
		    && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
			old_state = TCP_CONNTRACK_SYN_SENT;
			new_state = TCP_CONNTRACK_SYN_RECV;
			ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
				ct->proto.tcp.last_end;
			ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
				ct->proto.tcp.last_end;
			ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
				ct->proto.tcp.last_win == 0 ?
					1 : ct->proto.tcp.last_win;
			ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
				ct->proto.tcp.last_wscale;
			ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
				ct->proto.tcp.last_flags;
			memset(&ct->proto.tcp.seen[dir], 0,
			       sizeof(struct ip_ct_tcp_state));
			break;
		}
		ct->proto.tcp.last_index = index;
		ct->proto.tcp.last_dir = dir;
		ct->proto.tcp.last_seq = ntohl(th->seq);
		ct->proto.tcp.last_end =
		    segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
		ct->proto.tcp.last_win = ntohs(th->window);

		if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
			struct ip_ct_tcp_state seen = {};

			ct->proto.tcp.last_flags =
			ct->proto.tcp.last_wscale = 0;
			tcp_options(skb, dataoff, th, &seen);
			if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
				ct->proto.tcp.last_flags |=
					IP_CT_TCP_FLAG_WINDOW_SCALE;
				ct->proto.tcp.last_wscale = seen.td_scale;
			}
			if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
				ct->proto.tcp.last_flags |=
					IP_CT_TCP_FLAG_SACK_PERM;
			}
		}
		spin_unlock_bh(&ct->lock);
		if (LOG_INVALID(net, IPPROTO_TCP))
			nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
				  "nf_ct_tcp: invalid packet ignored ");
		return NF_ACCEPT;
	case TCP_CONNTRACK_MAX:
		
		pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
			 dir, get_conntrack_index(th), old_state);
		spin_unlock_bh(&ct->lock);
		if (LOG_INVALID(net, IPPROTO_TCP))
			nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
				  "nf_ct_tcp: invalid state ");
		return -NF_ACCEPT;
	case TCP_CONNTRACK_CLOSE:
		if (index == TCP_RST_SET
		    && (ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET)
		    && before(ntohl(th->seq), ct->proto.tcp.seen[!dir].td_maxack)) {
			
			spin_unlock_bh(&ct->lock);
			if (LOG_INVALID(net, IPPROTO_TCP))
				nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
					  "nf_ct_tcp: invalid RST ");
			return -NF_ACCEPT;
		}
		if (index == TCP_RST_SET
		    && ((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
			 && ct->proto.tcp.last_index == TCP_SYN_SET)
			|| (!test_bit(IPS_ASSURED_BIT, &ct->status)
			    && ct->proto.tcp.last_index == TCP_ACK_SET))
		    && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
			goto in_window;
		}
		
	default:
		
		break;
	}

	if (!tcp_in_window(ct, &ct->proto.tcp, dir, index,
			   skb, dataoff, th, pf)) {
		spin_unlock_bh(&ct->lock);
		return -NF_ACCEPT;
	}
     in_window:
	
	ct->proto.tcp.last_index = index;
	ct->proto.tcp.last_dir = dir;

	pr_debug("tcp_conntracks: ");
	nf_ct_dump_tuple(tuple);
	pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
		 (th->syn ? 1 : 0), (th->ack ? 1 : 0),
		 (th->fin ? 1 : 0), (th->rst ? 1 : 0),
		 old_state, new_state);

	ct->proto.tcp.state = new_state;
	if (old_state != new_state
	    && new_state == TCP_CONNTRACK_FIN_WAIT)
		ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;

	if (ct->proto.tcp.retrans >= nf_ct_tcp_max_retrans &&
	    timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
		timeout = timeouts[TCP_CONNTRACK_RETRANS];
	else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
		 IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
		 timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
		timeout = timeouts[TCP_CONNTRACK_UNACK];
	else
		timeout = timeouts[new_state];
	spin_unlock_bh(&ct->lock);

	if (new_state != old_state)
		nf_conntrack_event_cache(IPCT_PROTOINFO, ct);

	if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
		if (th->rst) {
			nf_ct_kill_acct(ct, ctinfo, skb);
			return NF_ACCEPT;
		}
	} else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
		   && (old_state == TCP_CONNTRACK_SYN_RECV
		       || old_state == TCP_CONNTRACK_ESTABLISHED)
		   && new_state == TCP_CONNTRACK_ESTABLISHED) {
		set_bit(IPS_ASSURED_BIT, &ct->status);
		nf_conntrack_event_cache(IPCT_ASSURED, ct);
	}
	nf_ct_refresh_acct(ct, ctinfo, skb, timeout);

	return NF_ACCEPT;
}
/* Returns verdict for packet, or -1 for invalid. */
static int tcp_packet(struct nf_conn *conntrack,
		      const struct sk_buff *skb,
		      unsigned int dataoff,
		      enum ip_conntrack_info ctinfo,
		      int pf,
		      unsigned int hooknum)
{
	enum tcp_conntrack new_state, old_state;
	enum ip_conntrack_dir dir;
	struct tcphdr *th, _tcph;
	unsigned long timeout;
	unsigned int index;

	th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
	BUG_ON(th == NULL);

	write_lock_bh(&tcp_lock);
	old_state = conntrack->proto.tcp.state;
	dir = CTINFO2DIR(ctinfo);
	index = get_conntrack_index(th);
	new_state = tcp_conntracks[dir][index][old_state];

	switch (new_state) {
	case TCP_CONNTRACK_IGNORE:
		/* Ignored packets:
		 *
		 * a) SYN in ORIGINAL
		 * b) SYN/ACK in REPLY
		 * c) ACK in reply direction after initial SYN in original.
		 */
		if (index == TCP_SYNACK_SET
		    && conntrack->proto.tcp.last_index == TCP_SYN_SET
		    && conntrack->proto.tcp.last_dir != dir
		    && ntohl(th->ack_seq) ==
			     conntrack->proto.tcp.last_end) {
			/* This SYN/ACK acknowledges a SYN that we earlier
			 * ignored as invalid. This means that the client and
			 * the server are both in sync, while the firewall is
			 * not. We kill this session and block the SYN/ACK so
			 * that the client cannot but retransmit its SYN and
			 * thus initiate a clean new session.
			 */
			write_unlock_bh(&tcp_lock);
			if (LOG_INVALID(IPPROTO_TCP))
				nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
					  "nf_ct_tcp: killing out of sync session ");
			if (del_timer(&conntrack->timeout))
				conntrack->timeout.function((unsigned long)
							    conntrack);
			return -NF_DROP;
		}
		conntrack->proto.tcp.last_index = index;
		conntrack->proto.tcp.last_dir = dir;
		conntrack->proto.tcp.last_seq = ntohl(th->seq);
		conntrack->proto.tcp.last_end =
		    segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);

		write_unlock_bh(&tcp_lock);
		if (LOG_INVALID(IPPROTO_TCP))
			nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
				  "nf_ct_tcp: invalid packed ignored ");
		return NF_ACCEPT;
	case TCP_CONNTRACK_MAX:
		/* Invalid packet */
		DEBUGP("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
		       dir, get_conntrack_index(th),
		       old_state);
		write_unlock_bh(&tcp_lock);
		if (LOG_INVALID(IPPROTO_TCP))
			nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
				  "nf_ct_tcp: invalid state ");
		return -NF_ACCEPT;
	case TCP_CONNTRACK_SYN_SENT:
		if (old_state < TCP_CONNTRACK_TIME_WAIT)
			break;
		if ((conntrack->proto.tcp.seen[dir].flags &
			IP_CT_TCP_FLAG_CLOSE_INIT)
		    || after(ntohl(th->seq),
			     conntrack->proto.tcp.seen[dir].td_end)) {
			/* Attempt to reopen a closed connection.
			* Delete this connection and look up again. */
			write_unlock_bh(&tcp_lock);
			if (del_timer(&conntrack->timeout))
				conntrack->timeout.function((unsigned long)
							    conntrack);
			return -NF_REPEAT;
		} else {
			write_unlock_bh(&tcp_lock);
			if (LOG_INVALID(IPPROTO_TCP))
				nf_log_packet(pf, 0, skb, NULL, NULL,
					      NULL, "nf_ct_tcp: invalid SYN");
			return -NF_ACCEPT;
		}
	case TCP_CONNTRACK_CLOSE:
		if (index == TCP_RST_SET
		    && ((test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)
			 && conntrack->proto.tcp.last_index == TCP_SYN_SET)
			|| (!test_bit(IPS_ASSURED_BIT, &conntrack->status)
			    && conntrack->proto.tcp.last_index == TCP_ACK_SET))
		    && ntohl(th->ack_seq) == conntrack->proto.tcp.last_end) {
			/* RST sent to invalid SYN or ACK we had let through
			 * at a) and c) above:
			 *
			 * a) SYN was in window then
			 * c) we hold a half-open connection.
			 *
			 * Delete our connection entry.
			 * We skip window checking, because packet might ACK
			 * segments we ignored. */
			goto in_window;
		}
		/* Just fall through */
	default:
		/* Keep compilers happy. */
		break;
	}

	if (!tcp_in_window(&conntrack->proto.tcp, dir, index,
			   skb, dataoff, th, pf)) {
		write_unlock_bh(&tcp_lock);
		return -NF_ACCEPT;
	}
     in_window:
	/* From now on we have got in-window packets */
	conntrack->proto.tcp.last_index = index;

	DEBUGP("tcp_conntracks: src=%u.%u.%u.%u:%hu dst=%u.%u.%u.%u:%hu "
	       "syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
		NIPQUAD(iph->saddr), ntohs(th->source),
		NIPQUAD(iph->daddr), ntohs(th->dest),
		(th->syn ? 1 : 0), (th->ack ? 1 : 0),
		(th->fin ? 1 : 0), (th->rst ? 1 : 0),
		old_state, new_state);

	conntrack->proto.tcp.state = new_state;
	if (old_state != new_state
	    && (new_state == TCP_CONNTRACK_FIN_WAIT
		|| new_state == TCP_CONNTRACK_CLOSE))
		conntrack->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
	timeout = conntrack->proto.tcp.retrans >= nf_ct_tcp_max_retrans
		  && *tcp_timeouts[new_state] > nf_ct_tcp_timeout_max_retrans
		  ? nf_ct_tcp_timeout_max_retrans : *tcp_timeouts[new_state];
	write_unlock_bh(&tcp_lock);

	nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);
	if (new_state != old_state)
		nf_conntrack_event_cache(IPCT_PROTOINFO, skb);

	if (!test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) {
		/* If only reply is a RST, we can consider ourselves not to
		   have an established connection: this is a fairly common
		   problem case, so we can delete the conntrack
		   immediately.  --RR */
		if (th->rst) {
			if (del_timer(&conntrack->timeout))
				conntrack->timeout.function((unsigned long)
							    conntrack);
			return NF_ACCEPT;
		}
	} else if (!test_bit(IPS_ASSURED_BIT, &conntrack->status)
		   && (old_state == TCP_CONNTRACK_SYN_RECV
		       || old_state == TCP_CONNTRACK_ESTABLISHED)
		   && new_state == TCP_CONNTRACK_ESTABLISHED) {
		/* Set ASSURED if we see see valid ack in ESTABLISHED
		   after SYN_RECV or a valid answer for a picked up
		   connection. */
		set_bit(IPS_ASSURED_BIT, &conntrack->status);
		nf_conntrack_event_cache(IPCT_STATUS, skb);
	}
	nf_ct_refresh_acct(conntrack, ctinfo, skb, timeout);

	return NF_ACCEPT;
}
/* Returns verdict for packet, or -1 for invalid. */
static int tcp_packet(struct nf_conn *ct,
		      struct sk_buff *skb,
		      unsigned int dataoff,
		      enum ip_conntrack_info ctinfo,
		      const struct nf_hook_state *state)
{
	struct net *net = nf_ct_net(ct);
	struct nf_tcp_net *tn = nf_tcp_pernet(net);
	struct nf_conntrack_tuple *tuple;
	enum tcp_conntrack new_state, old_state;
	unsigned int index, *timeouts;
	enum ip_conntrack_dir dir;
	const struct tcphdr *th;
	struct tcphdr _tcph;
	unsigned long timeout;

	th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
	if (th == NULL)
		return -NF_ACCEPT;

	if (tcp_error(th, skb, dataoff, state))
		return -NF_ACCEPT;

	if (!nf_ct_is_confirmed(ct) && !tcp_new(ct, skb, dataoff, th))
		return -NF_ACCEPT;

	spin_lock_bh(&ct->lock);
	old_state = ct->proto.tcp.state;
	dir = CTINFO2DIR(ctinfo);
	index = get_conntrack_index(th);
	new_state = tcp_conntracks[dir][index][old_state];
	tuple = &ct->tuplehash[dir].tuple;

	switch (new_state) {
	case TCP_CONNTRACK_SYN_SENT:
		if (old_state < TCP_CONNTRACK_TIME_WAIT)
			break;
		/* RFC 1122: "When a connection is closed actively,
		 * it MUST linger in TIME-WAIT state for a time 2xMSL
		 * (Maximum Segment Lifetime). However, it MAY accept
		 * a new SYN from the remote TCP to reopen the connection
		 * directly from TIME-WAIT state, if..."
		 * We ignore the conditions because we are in the
		 * TIME-WAIT state anyway.
		 *
		 * Handle aborted connections: we and the server
		 * think there is an existing connection but the client
		 * aborts it and starts a new one.
		 */
		if (((ct->proto.tcp.seen[dir].flags
		      | ct->proto.tcp.seen[!dir].flags)
		     & IP_CT_TCP_FLAG_CLOSE_INIT)
		    || (ct->proto.tcp.last_dir == dir
		        && ct->proto.tcp.last_index == TCP_RST_SET)) {
			/* Attempt to reopen a closed/aborted connection.
			 * Delete this connection and look up again. */
			spin_unlock_bh(&ct->lock);

			/* Only repeat if we can actually remove the timer.
			 * Destruction may already be in progress in process
			 * context and we must give it a chance to terminate.
			 */
			if (nf_ct_kill(ct))
				return -NF_REPEAT;
			return NF_DROP;
		}
		/* Fall through */
	case TCP_CONNTRACK_IGNORE:
		/* Ignored packets:
		 *
		 * Our connection entry may be out of sync, so ignore
		 * packets which may signal the real connection between
		 * the client and the server.
		 *
		 * a) SYN in ORIGINAL
		 * b) SYN/ACK in REPLY
		 * c) ACK in reply direction after initial SYN in original.
		 *
		 * If the ignored packet is invalid, the receiver will send
		 * a RST we'll catch below.
		 */
		if (index == TCP_SYNACK_SET
		    && ct->proto.tcp.last_index == TCP_SYN_SET
		    && ct->proto.tcp.last_dir != dir
		    && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
			/* b) This SYN/ACK acknowledges a SYN that we earlier
			 * ignored as invalid. This means that the client and
			 * the server are both in sync, while the firewall is
			 * not. We get in sync from the previously annotated
			 * values.
			 */
			old_state = TCP_CONNTRACK_SYN_SENT;
			new_state = TCP_CONNTRACK_SYN_RECV;
			ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
				ct->proto.tcp.last_end;
			ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
				ct->proto.tcp.last_end;
			ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
				ct->proto.tcp.last_win == 0 ?
					1 : ct->proto.tcp.last_win;
			ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
				ct->proto.tcp.last_wscale;
			ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
			ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
				ct->proto.tcp.last_flags;
			memset(&ct->proto.tcp.seen[dir], 0,
			       sizeof(struct ip_ct_tcp_state));
			break;
		}
		ct->proto.tcp.last_index = index;
		ct->proto.tcp.last_dir = dir;
		ct->proto.tcp.last_seq = ntohl(th->seq);
		ct->proto.tcp.last_end =
		    segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
		ct->proto.tcp.last_win = ntohs(th->window);

		/* a) This is a SYN in ORIGINAL. The client and the server
		 * may be in sync but we are not. In that case, we annotate
		 * the TCP options and let the packet go through. If it is a
		 * valid SYN packet, the server will reply with a SYN/ACK, and
		 * then we'll get in sync. Otherwise, the server potentially
		 * responds with a challenge ACK if implementing RFC5961.
		 */
		if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
			struct ip_ct_tcp_state seen = {};

			ct->proto.tcp.last_flags =
			ct->proto.tcp.last_wscale = 0;
			tcp_options(skb, dataoff, th, &seen);
			if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
				ct->proto.tcp.last_flags |=
					IP_CT_TCP_FLAG_WINDOW_SCALE;
				ct->proto.tcp.last_wscale = seen.td_scale;
			}
			if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
				ct->proto.tcp.last_flags |=
					IP_CT_TCP_FLAG_SACK_PERM;
			}
			/* Mark the potential for RFC5961 challenge ACK,
			 * this pose a special problem for LAST_ACK state
			 * as ACK is intrepretated as ACKing last FIN.
			 */
			if (old_state == TCP_CONNTRACK_LAST_ACK)
				ct->proto.tcp.last_flags |=
					IP_CT_EXP_CHALLENGE_ACK;
		}
		spin_unlock_bh(&ct->lock);
		nf_ct_l4proto_log_invalid(skb, ct, "invalid packet ignored in "
					  "state %s ", tcp_conntrack_names[old_state]);
		return NF_ACCEPT;
	case TCP_CONNTRACK_MAX:
		/* Special case for SYN proxy: when the SYN to the server or
		 * the SYN/ACK from the server is lost, the client may transmit
		 * a keep-alive packet while in SYN_SENT state. This needs to
		 * be associated with the original conntrack entry in order to
		 * generate a new SYN with the correct sequence number.
		 */
		if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT &&
		    index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL &&
		    ct->proto.tcp.last_dir == IP_CT_DIR_ORIGINAL &&
		    ct->proto.tcp.seen[dir].td_end - 1 == ntohl(th->seq)) {
			pr_debug("nf_ct_tcp: SYN proxy client keep alive\n");
			spin_unlock_bh(&ct->lock);
			return NF_ACCEPT;
		}

		/* Invalid packet */
		pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
			 dir, get_conntrack_index(th), old_state);
		spin_unlock_bh(&ct->lock);
		nf_ct_l4proto_log_invalid(skb, ct, "invalid state");
		return -NF_ACCEPT;
	case TCP_CONNTRACK_TIME_WAIT:
		/* RFC5961 compliance cause stack to send "challenge-ACK"
		 * e.g. in response to spurious SYNs.  Conntrack MUST
		 * not believe this ACK is acking last FIN.
		 */
		if (old_state == TCP_CONNTRACK_LAST_ACK &&
		    index == TCP_ACK_SET &&
		    ct->proto.tcp.last_dir != dir &&
		    ct->proto.tcp.last_index == TCP_SYN_SET &&
		    (ct->proto.tcp.last_flags & IP_CT_EXP_CHALLENGE_ACK)) {
			/* Detected RFC5961 challenge ACK */
			ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
			spin_unlock_bh(&ct->lock);
			nf_ct_l4proto_log_invalid(skb, ct, "challenge-ack ignored");
			return NF_ACCEPT; /* Don't change state */
		}
		break;
	case TCP_CONNTRACK_SYN_SENT2:
		/* tcp_conntracks table is not smart enough to handle
		 * simultaneous open.
		 */
		ct->proto.tcp.last_flags |= IP_CT_TCP_SIMULTANEOUS_OPEN;
		break;
	case TCP_CONNTRACK_SYN_RECV:
		if (dir == IP_CT_DIR_REPLY && index == TCP_ACK_SET &&
		    ct->proto.tcp.last_flags & IP_CT_TCP_SIMULTANEOUS_OPEN)
			new_state = TCP_CONNTRACK_ESTABLISHED;
		break;
	case TCP_CONNTRACK_CLOSE:
		if (index == TCP_RST_SET
		    && (ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET)
		    && before(ntohl(th->seq), ct->proto.tcp.seen[!dir].td_maxack)) {
			/* Invalid RST  */
			spin_unlock_bh(&ct->lock);
			nf_ct_l4proto_log_invalid(skb, ct, "invalid rst");
			return -NF_ACCEPT;
		}
		if (index == TCP_RST_SET
		    && ((test_bit(IPS_SEEN_REPLY_BIT, &ct->status)
			 && ct->proto.tcp.last_index == TCP_SYN_SET)
			|| (!test_bit(IPS_ASSURED_BIT, &ct->status)
			    && ct->proto.tcp.last_index == TCP_ACK_SET))
		    && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
			/* RST sent to invalid SYN or ACK we had let through
			 * at a) and c) above:
			 *
			 * a) SYN was in window then
			 * c) we hold a half-open connection.
			 *
			 * Delete our connection entry.
			 * We skip window checking, because packet might ACK
			 * segments we ignored. */
			goto in_window;
		}
		/* Just fall through */
	default:
		/* Keep compilers happy. */
		break;
	}

	if (!tcp_in_window(ct, &ct->proto.tcp, dir, index,
			   skb, dataoff, th)) {
		spin_unlock_bh(&ct->lock);
		return -NF_ACCEPT;
	}
     in_window:
	/* From now on we have got in-window packets */
	ct->proto.tcp.last_index = index;
	ct->proto.tcp.last_dir = dir;

	pr_debug("tcp_conntracks: ");
	nf_ct_dump_tuple(tuple);
	pr_debug("syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
		 (th->syn ? 1 : 0), (th->ack ? 1 : 0),
		 (th->fin ? 1 : 0), (th->rst ? 1 : 0),
		 old_state, new_state);

	ct->proto.tcp.state = new_state;
	if (old_state != new_state
	    && new_state == TCP_CONNTRACK_FIN_WAIT)
		ct->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;

	timeouts = nf_ct_timeout_lookup(ct);
	if (!timeouts)
		timeouts = tn->timeouts;

	if (ct->proto.tcp.retrans >= tn->tcp_max_retrans &&
	    timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
		timeout = timeouts[TCP_CONNTRACK_RETRANS];
	else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) &
		 IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
		 timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
		timeout = timeouts[TCP_CONNTRACK_UNACK];
	else if (ct->proto.tcp.last_win == 0 &&
		 timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
		timeout = timeouts[TCP_CONNTRACK_RETRANS];
	else
		timeout = timeouts[new_state];
	spin_unlock_bh(&ct->lock);

	if (new_state != old_state)
		nf_conntrack_event_cache(IPCT_PROTOINFO, ct);

	if (!test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
		/* If only reply is a RST, we can consider ourselves not to
		   have an established connection: this is a fairly common
		   problem case, so we can delete the conntrack
		   immediately.  --RR */
		if (th->rst) {
			nf_ct_kill_acct(ct, ctinfo, skb);
			return NF_ACCEPT;
		}
		/* ESTABLISHED without SEEN_REPLY, i.e. mid-connection
		 * pickup with loose=1. Avoid large ESTABLISHED timeout.
		 */
		if (new_state == TCP_CONNTRACK_ESTABLISHED &&
		    timeout > timeouts[TCP_CONNTRACK_UNACK])
			timeout = timeouts[TCP_CONNTRACK_UNACK];
	} else if (!test_bit(IPS_ASSURED_BIT, &ct->status)
		   && (old_state == TCP_CONNTRACK_SYN_RECV
		       || old_state == TCP_CONNTRACK_ESTABLISHED)
		   && new_state == TCP_CONNTRACK_ESTABLISHED) {
		/* Set ASSURED if we see see valid ack in ESTABLISHED
		   after SYN_RECV or a valid answer for a picked up
		   connection. */
		set_bit(IPS_ASSURED_BIT, &ct->status);
		nf_conntrack_event_cache(IPCT_ASSURED, ct);
	}
	nf_ct_refresh_acct(ct, ctinfo, skb, timeout);

	return NF_ACCEPT;
}
/* Called when a new connection for this protocol found. */
static int tcp_new(struct ip_conntrack *conntrack,
		   const struct sk_buff *skb)
{
	enum tcp_conntrack new_state;
	struct iphdr *iph = skb->nh.iph;
	struct tcphdr *th, _tcph;
#ifdef DEBUGP_VARS
	struct ip_ct_tcp_state *sender = &conntrack->proto.tcp.seen[0];
	struct ip_ct_tcp_state *receiver = &conntrack->proto.tcp.seen[1];
#endif

	th = skb_header_pointer(skb, iph->ihl * 4,
				sizeof(_tcph), &_tcph);
	BUG_ON(th == NULL);
	
	/* Don't need lock here: this conntrack not in circulation yet */
	new_state
		= tcp_conntracks[0][get_conntrack_index(th)]
		[TCP_CONNTRACK_NONE];

	/* Invalid: delete conntrack */
	if (new_state >= TCP_CONNTRACK_MAX) {
		DEBUGP("ip_ct_tcp: invalid new deleting.\n");
		return 0;
	}

	if (new_state == TCP_CONNTRACK_SYN_SENT) {
		/* SYN packet */
		conntrack->proto.tcp.seen[0].td_end =
			segment_seq_plus_len(ntohl(th->seq), skb->len,
					     iph, th);
		conntrack->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
		if (conntrack->proto.tcp.seen[0].td_maxwin == 0)
			conntrack->proto.tcp.seen[0].td_maxwin = 1;
		conntrack->proto.tcp.seen[0].td_maxend =
			conntrack->proto.tcp.seen[0].td_end;

		tcp_options(skb, iph, th, &conntrack->proto.tcp.seen[0]);
		conntrack->proto.tcp.seen[1].flags = 0;
		conntrack->proto.tcp.seen[0].loose = 
		conntrack->proto.tcp.seen[1].loose = 0;
	} else if (ip_ct_tcp_loose == 0) {
		/* Don't try to pick up connections. */
		return 0;
	} else {
		/*
		 * We are in the middle of a connection,
		 * its history is lost for us.
		 * Let's try to use the data from the packet.
		 */
		conntrack->proto.tcp.seen[0].td_end =
			segment_seq_plus_len(ntohl(th->seq), skb->len,
					     iph, th);
		conntrack->proto.tcp.seen[0].td_maxwin = ntohs(th->window);
		if (conntrack->proto.tcp.seen[0].td_maxwin == 0)
			conntrack->proto.tcp.seen[0].td_maxwin = 1;
		conntrack->proto.tcp.seen[0].td_maxend =
			conntrack->proto.tcp.seen[0].td_end + 
			conntrack->proto.tcp.seen[0].td_maxwin;
		conntrack->proto.tcp.seen[0].td_scale = 0;

		/* We assume SACK. Should we assume window scaling too? */
		conntrack->proto.tcp.seen[0].flags =
		conntrack->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM;
		conntrack->proto.tcp.seen[0].loose = 
		conntrack->proto.tcp.seen[1].loose = ip_ct_tcp_loose;
	}
    
	conntrack->proto.tcp.seen[1].td_end = 0;
	conntrack->proto.tcp.seen[1].td_maxend = 0;
	conntrack->proto.tcp.seen[1].td_maxwin = 1;
	conntrack->proto.tcp.seen[1].td_scale = 0;      

	/* tcp_packet will set them */
	conntrack->proto.tcp.state = TCP_CONNTRACK_NONE;
	conntrack->proto.tcp.last_index = TCP_NONE_SET;
	 
	DEBUGP("tcp_new: sender end=%u maxend=%u maxwin=%u scale=%i "
	       "receiver end=%u maxend=%u maxwin=%u scale=%i\n",
		sender->td_end, sender->td_maxend, sender->td_maxwin,
		sender->td_scale, 
		receiver->td_end, receiver->td_maxend, receiver->td_maxwin,
		receiver->td_scale);
	return 1;
}
/* Returns verdict for packet, or -1 for invalid. */
static int tcp_packet(struct ip_conntrack *conntrack,
		      const struct sk_buff *skb,
		      enum ip_conntrack_info ctinfo)
{
	enum tcp_conntrack new_state, old_state;
	enum ip_conntrack_dir dir;
	struct iphdr *iph = skb->nh.iph;
	struct tcphdr *th, _tcph;
	unsigned long timeout;
	unsigned int index;
	
	th = skb_header_pointer(skb, iph->ihl * 4,
				sizeof(_tcph), &_tcph);
	BUG_ON(th == NULL);
	
	WRITE_LOCK(&tcp_lock);
	old_state = conntrack->proto.tcp.state;
	dir = CTINFO2DIR(ctinfo);
	index = get_conntrack_index(th);
	new_state = tcp_conntracks[dir][index][old_state];

	switch (new_state) {
	case TCP_CONNTRACK_IGNORE:
		/* Either SYN in ORIGINAL
		 * or SYN/ACK in REPLY
		 * or ACK in REPLY direction (half-open connection). */
		if (index == TCP_SYNACK_SET
		    && conntrack->proto.tcp.last_index == TCP_SYN_SET
		    && conntrack->proto.tcp.last_dir != dir
		    && after(ntohl(th->ack_seq),
		    	     conntrack->proto.tcp.last_seq)) {
			/* This SYN/ACK acknowledges a SYN that we earlier 
			 * ignored as invalid. This means that the client and
			 * the server are both in sync, while the firewall is
			 * not. We kill this session and block the SYN/ACK so
			 * that the client cannot but retransmit its SYN and 
			 * thus initiate a clean new session.
			 */
		    	WRITE_UNLOCK(&tcp_lock);
			if (LOG_INVALID(IPPROTO_TCP))
				nf_log_packet(PF_INET, 0, skb, NULL, NULL, 
					  "ip_ct_tcp: killing out of sync session ");
		    	if (del_timer(&conntrack->timeout))
		    		conntrack->timeout.function((unsigned long)
		    					    conntrack);
		    	return -NF_DROP;
		}
		conntrack->proto.tcp.last_index = index;
		conntrack->proto.tcp.last_dir = dir;
		conntrack->proto.tcp.last_seq = ntohl(th->seq);
		
		WRITE_UNLOCK(&tcp_lock);
		if (LOG_INVALID(IPPROTO_TCP))
			nf_log_packet(PF_INET, 0, skb, NULL, NULL, 
				  "ip_ct_tcp: invalid packet ignored ");
		return NF_ACCEPT;
	case TCP_CONNTRACK_MAX:
		/* Invalid packet */
		DEBUGP("ip_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
		       dir, get_conntrack_index(th),
		       old_state);
		WRITE_UNLOCK(&tcp_lock);
		if (LOG_INVALID(IPPROTO_TCP))
			nf_log_packet(PF_INET, 0, skb, NULL, NULL, 
				  "ip_ct_tcp: invalid state ");
		return -NF_ACCEPT;
	case TCP_CONNTRACK_SYN_SENT:
		if (old_state >= TCP_CONNTRACK_TIME_WAIT) {	
		    	/* Attempt to reopen a closed connection.
		    	* Delete this connection and look up again. */
		    	WRITE_UNLOCK(&tcp_lock);
		    	if (del_timer(&conntrack->timeout))
		    		conntrack->timeout.function((unsigned long)
		    					    conntrack);
		    	return -NF_REPEAT;
		}
		break;
	case TCP_CONNTRACK_CLOSE:
		if (index == TCP_RST_SET
		    && ((test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)
		         && conntrack->proto.tcp.last_index <= TCP_SYNACK_SET)
		        || (!test_bit(IPS_ASSURED_BIT, &conntrack->status)
			 && conntrack->proto.tcp.last_index == TCP_ACK_SET))
		    && after(ntohl(th->ack_seq),
		    	     conntrack->proto.tcp.last_seq)) {
			/* Ignore RST closing down invalid SYN or ACK
			   we had let trough. */ 
		    	WRITE_UNLOCK(&tcp_lock);
			if (LOG_INVALID(IPPROTO_TCP))
				nf_log_packet(PF_INET, 0, skb, NULL, NULL, 
					  "ip_ct_tcp: invalid RST (ignored) ");
			return NF_ACCEPT;
		}
		/* Just fall trough */
	default:
		/* Keep compilers happy. */
		break;
	}

	if (!tcp_in_window(&conntrack->proto.tcp, dir, &index, 
			   skb, iph, th)) {
		WRITE_UNLOCK(&tcp_lock);
		return -NF_ACCEPT;
	}
	/* From now on we have got in-window packets */
	
	/* If FIN was trimmed off, we don't change state. */
	conntrack->proto.tcp.last_index = index;
	new_state = tcp_conntracks[dir][index][old_state];

	DEBUGP("tcp_conntracks: src=%u.%u.%u.%u:%hu dst=%u.%u.%u.%u:%hu "
	       "syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
		NIPQUAD(iph->saddr), ntohs(th->source),
		NIPQUAD(iph->daddr), ntohs(th->dest),
		(th->syn ? 1 : 0), (th->ack ? 1 : 0),
		(th->fin ? 1 : 0), (th->rst ? 1 : 0),
		old_state, new_state);

	conntrack->proto.tcp.state = new_state;
	timeout = conntrack->proto.tcp.retrans >= ip_ct_tcp_max_retrans
		  && *tcp_timeouts[new_state] > ip_ct_tcp_timeout_max_retrans
		  ? ip_ct_tcp_timeout_max_retrans : *tcp_timeouts[new_state];
	WRITE_UNLOCK(&tcp_lock);

	if (!test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) {
		/* If only reply is a RST, we can consider ourselves not to
		   have an established connection: this is a fairly common
		   problem case, so we can delete the conntrack
		   immediately.  --RR */
		if (th->rst) {
			if (del_timer(&conntrack->timeout))
				conntrack->timeout.function((unsigned long)
							    conntrack);
			return NF_ACCEPT;
		}
	} else if (!test_bit(IPS_ASSURED_BIT, &conntrack->status)
		   && (old_state == TCP_CONNTRACK_SYN_RECV
		       || old_state == TCP_CONNTRACK_ESTABLISHED)
		   && new_state == TCP_CONNTRACK_ESTABLISHED) {
		/* Set ASSURED if we see see valid ack in ESTABLISHED 
		   after SYN_RECV or a valid answer for a picked up 
		   connection. */
			set_bit(IPS_ASSURED_BIT, &conntrack->status);
	}
	ip_ct_refresh_acct(conntrack, ctinfo, skb, timeout);

	return NF_ACCEPT;
}
/* Returns verdict for packet, or -1 for invalid. */
static int tcp_packet(struct ip_conntrack *conntrack,
		      enum ip_conntrack_info ctinfo,
			  struct sk_buff *skb, int hooknum)
{
	struct iphdr *iph = skb->nh.iph;
	size_t len = skb->len;
	enum tcp_conntrack new_state, old_state;
	enum ip_conntrack_dir dir;
	struct tcphdr *tcph = (struct tcphdr *)((u_int32_t *)iph + iph->ihl);
	unsigned long timeout;
	unsigned int index;
	
	/* Do not handle unclean packets, which could cause false alarms. */
	if (tcp_error(skb, hooknum) != NF_ACCEPT)
		return -NF_ACCEPT;
	
	WRITE_LOCK(&tcp_lock);
	old_state = conntrack->proto.tcp.state;
	dir = CTINFO2DIR(ctinfo);
	index = get_conntrack_index(tcph);
	new_state = tcp_conntracks[dir][index][old_state];

	switch (new_state) {
	case TCP_CONNTRACK_IGNORE:
		/* Either SYN in ORIGINAL
		 * or SYN/ACK in REPLY. */
		if (index == TCP_SYNACK_SET
		    && conntrack->proto.tcp.last_index == TCP_SYN_SET
		    && conntrack->proto.tcp.last_dir != dir
		    && ntohl(tcph->ack_seq) ==
		    	     conntrack->proto.tcp.last_end) {
			/* This SYN/ACK acknowledges a SYN that we earlier 
			 * ignored as invalid. This means that the client and
			 * the server are both in sync, while the firewall is
			 * not. We kill this session and block the SYN/ACK so
			 * that the client cannot but retransmit its SYN and 
			 * thus initiate a clean new session.
			 */
		    	WRITE_UNLOCK(&tcp_lock);
			if (NET_RATELIMIT(ip_ct_tcp_log_invalid))
				nf_log(PF_INET, (char *)iph, len, 
					"ip_ct_tcp: killing out of sync session ");
		    	if (del_timer(&conntrack->timeout))
		    		conntrack->timeout.function((unsigned long)
		    					    conntrack);
		    	return -NF_DROP;
		}
		conntrack->proto.tcp.last_index = index;
		conntrack->proto.tcp.last_dir = dir;
		conntrack->proto.tcp.last_seq = ntohl(tcph->seq);
		conntrack->proto.tcp.last_end = 
		    segment_seq_plus_len(ntohl(tcph->seq), len, iph, tcph);
		
		WRITE_UNLOCK(&tcp_lock);
		if (NET_RATELIMIT(ip_ct_tcp_log_invalid))
			nf_log(PF_INET, (char *)iph, len, 
				"ip_ct_tcp: invalid packet ignored ");
		return NF_ACCEPT;
	case TCP_CONNTRACK_MAX:
		/* Invalid packet */
		DEBUGP("ip_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
		       dir, get_conntrack_index(tcph),
		       old_state);
		WRITE_UNLOCK(&tcp_lock);
		if (NET_RATELIMIT(ip_ct_tcp_log_invalid))
			nf_log(PF_INET, (char *)iph, len, 
				"ip_ct_tcp: invalid state ");
		return -NF_ACCEPT;
	case TCP_CONNTRACK_SYN_SENT:
		if (old_state < TCP_CONNTRACK_TIME_WAIT)
			break;
		if ((conntrack->proto.tcp.seen[dir].flags &
		         IP_CT_TCP_FLAG_CLOSE_INIT)
		    || after(ntohl(tcph->seq),
		    	     conntrack->proto.tcp.seen[dir].td_end)) {	
		    	/* Attempt to reopen a closed connection.
		    	* Delete this connection and look up again. */
		    	WRITE_UNLOCK(&tcp_lock);
		    	if (del_timer(&conntrack->timeout))
		    		conntrack->timeout.function((unsigned long)
		    					    conntrack);
		    	return -NF_REPEAT;
		} else {
			WRITE_UNLOCK(&tcp_lock);
			if (NET_RATELIMIT(ip_ct_tcp_log_invalid))
				nf_log(PF_INET, (char *)iph, len, 
					"ip_ct_tcp: invalid SYN ");
			return -NF_ACCEPT;
		}
	case TCP_CONNTRACK_CLOSE:
		if (index == TCP_RST_SET
		    && test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)
		    && conntrack->proto.tcp.last_index == TCP_SYN_SET
		    && ntohl(tcph->ack_seq) == conntrack->proto.tcp.last_end) {
			/* RST sent to invalid SYN we had let trough 
			 * SYN was in window then, tear down connection.
			 * We skip window checking, because packet might ACK
			 * segments we ignored in the SYN. */
			goto in_window;
		}
		/* Just fall trough */
	default:
		/* Keep compilers happy. */
		break;
	}

	if (!tcp_in_window(&conntrack->proto.tcp, dir, index, 
			   iph, len, tcph)) {
		WRITE_UNLOCK(&tcp_lock);
		return -NF_ACCEPT;
	}
    in_window:
	/* From now on we have got in-window packets */	
	conntrack->proto.tcp.last_index = index;

	DEBUGP("tcp_conntracks: src=%u.%u.%u.%u:%hu dst=%u.%u.%u.%u:%hu "
	       "syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n",
		NIPQUAD(iph->saddr), ntohs(tcph->source),
		NIPQUAD(iph->daddr), ntohs(tcph->dest),
		(tcph->syn ? 1 : 0), (tcph->ack ? 1 : 0),
		(tcph->fin ? 1 : 0), (tcph->rst ? 1 : 0),
		old_state, new_state);

	conntrack->proto.tcp.state = new_state;
	if (old_state != new_state 
	    && (new_state == TCP_CONNTRACK_FIN_WAIT
	    	|| new_state == TCP_CONNTRACK_CLOSE))
		conntrack->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
	timeout = conntrack->proto.tcp.retrans >= ip_ct_tcp_max_retrans
		  && *tcp_timeouts[new_state] > ip_ct_tcp_timeout_max_retrans
		  ? ip_ct_tcp_timeout_max_retrans : *tcp_timeouts[new_state];
	WRITE_UNLOCK(&tcp_lock);

	if (!test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) {
		/* If only reply is a RST, we can consider ourselves not to
		   have an established connection: this is a fairly common
		   problem case, so we can delete the conntrack
		   immediately.  --RR */
		if (tcph->rst) {
			if (del_timer(&conntrack->timeout))
				conntrack->timeout.function((unsigned long)
							    conntrack);
			return NF_ACCEPT;
		}
	} else if (!test_bit(IPS_ASSURED_BIT, &conntrack->status)
		   && (old_state == TCP_CONNTRACK_SYN_RECV
		       || old_state == TCP_CONNTRACK_ESTABLISHED)
		   && new_state == TCP_CONNTRACK_ESTABLISHED) {
		/* Set ASSURED if we see see valid ack in ESTABLISHED 
		   after SYN_RECV or a valid answer for a picked up 
		   connection. */
			set_bit(IPS_ASSURED_BIT, &conntrack->status);
	}
	ip_ct_refresh_acct(conntrack, ctinfo, iph, timeout);

	return NF_ACCEPT;
}
/* Returns verdict for packet, or -1 for invalid. */
static int tcp_packet(struct ip_conntrack *conntrack,
		      const struct sk_buff *skb,
		      enum ip_conntrack_info ctinfo)
{
	enum tcp_conntrack newconntrack, oldtcpstate;
	struct tcphdr tcph;

	if (skb_copy_bits(skb, skb->nh.iph->ihl * 4, &tcph, sizeof(tcph)) != 0)
		return -1;
	if (skb->len < skb->nh.iph->ihl * 4 + tcph.doff * 4)
		return -1;

	/* If only reply is a RST, we can consider ourselves not to
	   have an established connection: this is a fairly common
	   problem case, so we can delete the conntrack
	   immediately.  --RR */
	if (!test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status) && tcph.rst) {
		if (del_timer(&conntrack->timeout))
			conntrack->timeout.function((unsigned long)conntrack);
		return NF_ACCEPT;
	}

	WRITE_LOCK(&tcp_lock);
	oldtcpstate = conntrack->proto.tcp.state;
	newconntrack
		= tcp_conntracks
		[CTINFO2DIR(ctinfo)]
		[get_conntrack_index(&tcph)][oldtcpstate];

	/* Invalid */
	if (newconntrack == TCP_CONNTRACK_MAX) {
		DEBUGP("ip_conntrack_tcp: Invalid dir=%i index=%u conntrack=%u\n",
		       CTINFO2DIR(ctinfo), get_conntrack_index(&tcph),
		       conntrack->proto.tcp.state);
		WRITE_UNLOCK(&tcp_lock);
		return -1;
	}

	conntrack->proto.tcp.state = newconntrack;

	/* Poor man's window tracking: record SYN/ACK for handshake check */
	if (oldtcpstate == TCP_CONNTRACK_SYN_SENT
	    && CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY
	    && tcph.syn && tcph.ack) {
		conntrack->proto.tcp.handshake_ack
			= htonl(ntohl(tcph.seq) + 1);
		goto out;
	}

	/* Set ASSURED if we see valid ack in ESTABLISHED after SYN_RECV */
	if (oldtcpstate == TCP_CONNTRACK_SYN_RECV
	    && CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL
	    && tcph.ack && !tcph.syn
	    && tcph.ack_seq == conntrack->proto.tcp.handshake_ack)
		set_bit(IPS_ASSURED_BIT, &conntrack->status);

out:	WRITE_UNLOCK(&tcp_lock);
	ip_ct_refresh(conntrack, *tcp_timeouts[newconntrack]);

	return NF_ACCEPT;
}