Ejemplo n.º 1
0
/* Returns verdict for packet, and may modify conntracktype */
int nf_conntrack_udplite_packet(struct nf_conn *ct,
				struct sk_buff *skb,
				unsigned int dataoff,
				enum ip_conntrack_info ctinfo,
				const struct nf_hook_state *state)
{
	unsigned int *timeouts;

	if (udplite_error(skb, dataoff, state))
		return -NF_ACCEPT;

	timeouts = nf_ct_timeout_lookup(ct);
	if (!timeouts)
		timeouts = udp_get_timeouts(nf_ct_net(ct));

	/* If we've seen traffic both ways, this is some kind of UDP
	   stream.  Extend timeout. */
	if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
		nf_ct_refresh_acct(ct, ctinfo, skb,
				   timeouts[UDP_CT_REPLIED]);
		/* Also, more likely to be important, and not a probe */
		if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
			nf_conntrack_event_cache(IPCT_ASSURED, ct);
	} else {
		nf_ct_refresh_acct(ct, ctinfo, skb,
				   timeouts[UDP_CT_UNREPLIED]);
	}
	return NF_ACCEPT;
}
/* Returns verdict for packet, and may modify conntracktype */
static int udp_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)
{
	/* If we've seen traffic both ways, this is some kind of UDP
	   stream.  Extend timeout. */
	if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
#ifdef CONFIG_MIPS_BRCM
                unsigned timeout = nf_ct_udp_timeout_stream;
                if (ct->derived_timeout == 0xFFFFFFFF){
                        timeout = 0xFFFFFFFF - jiffies;
                } else if(ct->derived_timeout > 0) {
                        timeout = ct->derived_timeout;
                }
                nf_ct_refresh_acct(ct, ctinfo, skb, timeout);
#else
		nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_udp_timeout_stream);
#endif
		/* Also, more likely to be important, and not a probe */
		if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
			nf_conntrack_event_cache(IPCT_STATUS, ct);
	} else
		nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_udp_timeout);

	return NF_ACCEPT;
}
/* Returns verdict for packet, and may modify conntracktype */
static int udp_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)
{
	/* If we've seen traffic both ways, this is some kind of UDP
	   stream.  Extend timeout. */
	if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
/* Dino @20120203 */
#if defined(CONFIG_CAMEO_CT_NEW)
		if(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num == AF_INET6)
		{
			if((ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port < 1024) ||
			   (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u.udp.port < 1024))
			{
				cameo_nf_ct_refresh_acct_udp(ct, ctinfo, skb, nf_ct_udp6_timeout_stream, "AS"); // assured
			}
			else
			{
				cameo_nf_ct_refresh_acct_udp(ct, ctinfo, skb, nf_ct_udp6_timeout_stream_out_wkport, "AS"); // assured
			}
		}
		else
		{
			cameo_nf_ct_refresh_acct_udp(ct, ctinfo, skb, nf_ct_udp_timeout_stream, "AS"); // assured
		}
#else
/* Dino */
		nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_udp_timeout_stream);
#endif
		/* Also, more likely to be important, and not a probe */
		if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
			nf_conntrack_event_cache(IPCT_ASSURED, ct);
	} else
/* Dino @20120203 */
#if defined(CONFIG_CAMEO_CT_NEW)
		if(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num ==AF_INET6)
			cameo_nf_ct_refresh_acct_udp(ct, ctinfo, skb, nf_ct_udp6_timeout, "UR"); // unreplied
		else
			cameo_nf_ct_refresh_acct_udp(ct, ctinfo, skb, nf_ct_udp_timeout, "UR"); // unreplied
#else
/* Dino */
		nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_udp_timeout);
#endif

	return NF_ACCEPT;
}
Ejemplo n.º 4
0
/* Returns verdict for packet, or -1 for invalid. */
static int 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)
{
	nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_generic_timeout);
	return NF_ACCEPT;
}
Ejemplo n.º 5
0
/* Returns verdict for packet, and may modify conntracktype */
static int udp_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)
{
	/* If we've seen traffic both ways, this is some kind of UDP
	   stream.  Extend timeout. */
	if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
		nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_udp_timeout_stream);
		/* Also, more likely to be important, and not a probe */
		if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
			nf_conntrack_event_cache(IPCT_ASSURED, ct);
	} else
		nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_udp_timeout);

	return NF_ACCEPT;
}
Ejemplo n.º 6
0
/* Returns verdict for packet, and may modify conntracktype */
int nf_conntrack_udp_packet(struct nf_conn *ct,
			    struct sk_buff *skb,
			    unsigned int dataoff,
			    enum ip_conntrack_info ctinfo,
			    const struct nf_hook_state *state)
{
	unsigned int *timeouts;

	if (udp_error(skb, dataoff, state))
		return -NF_ACCEPT;

	timeouts = nf_ct_timeout_lookup(ct);
	if (!timeouts)
		timeouts = udp_get_timeouts(nf_ct_net(ct));

	if (!nf_ct_is_confirmed(ct))
		ct->proto.udp.stream_ts = 2 * HZ + jiffies;

	/* If we've seen traffic both ways, this is some kind of UDP
	 * stream. Set Assured.
	 */
	if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
		unsigned long extra = timeouts[UDP_CT_UNREPLIED];

		/* Still active after two seconds? Extend timeout. */
		if (time_after(jiffies, ct->proto.udp.stream_ts))
			extra = timeouts[UDP_CT_REPLIED];

		nf_ct_refresh_acct(ct, ctinfo, skb, extra);

		/* Also, more likely to be important, and not a probe */
		if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
			nf_conntrack_event_cache(IPCT_ASSURED, ct);
	} else {
		nf_ct_refresh_acct(ct, ctinfo, skb,
				   timeouts[UDP_CT_UNREPLIED]);
	}
	return NF_ACCEPT;
}
/* Returns verdict for packet, or -1 for invalid. */
static int icmpv6_packet(struct nf_conn *ct,
		       const struct sk_buff *skb,
		       unsigned int dataoff,
		       enum ip_conntrack_info ctinfo,
		       unsigned int *timeout)
{
	/* Do not immediately delete the connection after the first
	   successful reply to avoid excessive conntrackd traffic
	   and also to handle correctly ICMP echo reply duplicates. */
	nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);

	return NF_ACCEPT;
}
static int udp_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)
{
	/*                                                          
                             */
	if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
		nf_ct_refresh_acct(ct, ctinfo, skb,
				   timeouts[UDP_CT_REPLIED]);
		/*                                                    */
		if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
			nf_conntrack_event_cache(IPCT_ASSURED, ct);
	} else {
		nf_ct_refresh_acct(ct, ctinfo, skb,
				   timeouts[UDP_CT_UNREPLIED]);
	}
	return NF_ACCEPT;
}
/* Returns verdict for packet, or -1 for invalid. */
static int icmp_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)
{
	/* Try to delete connection immediately after all replies:
	   won't actually vanish as we still have skb, and del_timer
	   means this will only run once even if count hits zero twice
	   (theoretically possible with SMP) */
	if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
		if (atomic_dec_and_test(&ct->proto.icmp.count))
			nf_ct_kill_acct(ct, ctinfo, skb);
	} else {
		atomic_inc(&ct->proto.icmp.count);
		nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, ct);
		nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmp_timeout);
	}

	return NF_ACCEPT;
}
Ejemplo n.º 10
0
/* Returns verdict for packet, or -1 for invalid. */
static int icmpv6_packet(struct nf_conn *ct,
		         struct sk_buff *skb,
		         unsigned int dataoff,
		         enum ip_conntrack_info ctinfo,
		         const struct nf_hook_state *state)
{
	unsigned int *timeout = nf_ct_timeout_lookup(ct);
	static const u8 valid_new[] = {
		[ICMPV6_ECHO_REQUEST - 128] = 1,
		[ICMPV6_NI_QUERY - 128] = 1
	};

	if (state->pf != NFPROTO_IPV6)
		return -NF_ACCEPT;

	if (!nf_ct_is_confirmed(ct)) {
		int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;

		if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
			/* Can't create a new ICMPv6 `conn' with this. */
			pr_debug("icmpv6: can't create new conn with type %u\n",
				 type + 128);
			nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
			return -NF_ACCEPT;
		}
	}

	if (!timeout)
		timeout = icmpv6_get_timeouts(nf_ct_net(ct));

	/* Do not immediately delete the connection after the first
	   successful reply to avoid excessive conntrackd traffic
	   and also to handle correctly ICMP echo reply duplicates. */
	nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);

	return NF_ACCEPT;
}
static int dccp_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);
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	struct dccp_hdr _dh, *dh;
	u_int8_t type, old_state, new_state;
	enum ct_dccp_roles role;

	dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &_dh);
	BUG_ON(dh == NULL);
	type = dh->dccph_type;

	if (type == DCCP_PKT_RESET &&
	    !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
		/* Tear down connection immediately if only reply is a RESET */
		nf_ct_kill_acct(ct, ctinfo, skb);
		return NF_ACCEPT;
	}

	spin_lock_bh(&ct->lock);

	role = ct->proto.dccp.role[dir];
	old_state = ct->proto.dccp.state;
	new_state = dccp_state_table[role][type][old_state];

	switch (new_state) {
	case CT_DCCP_REQUEST:
		if (old_state == CT_DCCP_TIMEWAIT &&
		    role == CT_DCCP_ROLE_SERVER) {
			/* Reincarnation in the reverse direction: reopen and
			 * reverse client/server roles. */
			ct->proto.dccp.role[dir] = CT_DCCP_ROLE_CLIENT;
			ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_SERVER;
		}
		break;
	case CT_DCCP_RESPOND:
		if (old_state == CT_DCCP_REQUEST)
			ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
		break;
	case CT_DCCP_PARTOPEN:
		if (old_state == CT_DCCP_RESPOND &&
		    type == DCCP_PKT_ACK &&
		    dccp_ack_seq(dh) == ct->proto.dccp.handshake_seq)
			set_bit(IPS_ASSURED_BIT, &ct->status);
		break;
	case CT_DCCP_IGNORE:
		/*
		 * Connection tracking might be out of sync, so we ignore
		 * packets that might establish a new connection and resync
		 * if the server responds with a valid Response.
		 */
		if (ct->proto.dccp.last_dir == !dir &&
		    ct->proto.dccp.last_pkt == DCCP_PKT_REQUEST &&
		    type == DCCP_PKT_RESPONSE) {
			ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_CLIENT;
			ct->proto.dccp.role[dir] = CT_DCCP_ROLE_SERVER;
			ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
			new_state = CT_DCCP_RESPOND;
			break;
		}
		ct->proto.dccp.last_dir = dir;
		ct->proto.dccp.last_pkt = type;

		spin_unlock_bh(&ct->lock);
		if (LOG_INVALID(net, IPPROTO_DCCP))
			nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
				      "nf_ct_dccp: invalid packet ignored ");
		return NF_ACCEPT;
	case CT_DCCP_INVALID:
		spin_unlock_bh(&ct->lock);
		if (LOG_INVALID(net, IPPROTO_DCCP))
			nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
				      "nf_ct_dccp: invalid state transition ");
		return -NF_ACCEPT;
	}

	ct->proto.dccp.last_dir = dir;
	ct->proto.dccp.last_pkt = type;
	ct->proto.dccp.state = new_state;
	spin_unlock_bh(&ct->lock);

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

	nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[new_state]);

	return NF_ACCEPT;
}
Ejemplo n.º 12
0
/* 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;
}
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;
}
Ejemplo n.º 15
0
/* 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;
}
Ejemplo n.º 16
0
static int dccp_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 dccp_net *dn;
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	struct dccp_hdr _dh, *dh;
	u_int8_t type, old_state, new_state;
	enum ct_dccp_roles role;

	dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
	BUG_ON(dh == NULL);
	type = dh->dccph_type;

	if (type == DCCP_PKT_RESET &&
	    !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
		
		nf_ct_kill_acct(ct, ctinfo, skb);
		return NF_ACCEPT;
	}

	spin_lock_bh(&ct->lock);

	role = ct->proto.dccp.role[dir];
	old_state = ct->proto.dccp.state;
	new_state = dccp_state_table[role][type][old_state];

	switch (new_state) {
	case CT_DCCP_REQUEST:
		if (old_state == CT_DCCP_TIMEWAIT &&
		    role == CT_DCCP_ROLE_SERVER) {
			
			ct->proto.dccp.role[dir] = CT_DCCP_ROLE_CLIENT;
			ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_SERVER;
		}
		break;
	case CT_DCCP_RESPOND:
		if (old_state == CT_DCCP_REQUEST)
			ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
		break;
	case CT_DCCP_PARTOPEN:
		if (old_state == CT_DCCP_RESPOND &&
		    type == DCCP_PKT_ACK &&
		    dccp_ack_seq(dh) == ct->proto.dccp.handshake_seq)
			set_bit(IPS_ASSURED_BIT, &ct->status);
		break;
	case CT_DCCP_IGNORE:
		
		if (ct->proto.dccp.last_dir == !dir &&
		    ct->proto.dccp.last_pkt == DCCP_PKT_REQUEST &&
		    type == DCCP_PKT_RESPONSE) {
			ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_CLIENT;
			ct->proto.dccp.role[dir] = CT_DCCP_ROLE_SERVER;
			ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
			new_state = CT_DCCP_RESPOND;
			break;
		}
		ct->proto.dccp.last_dir = dir;
		ct->proto.dccp.last_pkt = type;

		spin_unlock_bh(&ct->lock);
		if (LOG_INVALID(net, IPPROTO_DCCP))
			nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
				      "nf_ct_dccp: invalid packet ignored ");
		return NF_ACCEPT;
	case CT_DCCP_INVALID:
		spin_unlock_bh(&ct->lock);
		if (LOG_INVALID(net, IPPROTO_DCCP))
			nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
				      "nf_ct_dccp: invalid state transition ");
		return -NF_ACCEPT;
	}

	ct->proto.dccp.last_dir = dir;
	ct->proto.dccp.last_pkt = type;
	ct->proto.dccp.state = new_state;
	spin_unlock_bh(&ct->lock);

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

	dn = dccp_pernet(net);
	nf_ct_refresh_acct(ct, ctinfo, skb, dn->dccp_timeout[new_state]);

	return NF_ACCEPT;
}