Commit 4bdc3d66 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp/dccp: fix behavior of stale SYN_RECV request sockets 



When a TCP/DCCP listener is closed, its pending SYN_RECV request sockets
become stale, meaning 3WHS can not complete.

But current behavior is wrong :
incoming packets finding such stale sockets are dropped.

We need instead to cleanup the request socket and perform another
lookup :
- Incoming ACK will give a RST answer,
- SYN rtx might find another listener if available.
- We expedite cleanup of request sockets and old listener socket.

Fixes: 079096f1 ("tcp/dccp: install syn_recv requests into ehash table")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent bbb300eb

net/dccp/ipv4.c

+7 −8
Original line number Diff line number Diff line
@@ -799,15 +799,10 @@ static int dccp_v4_rcv(struct sk_buff *skb) 
				  DCCP_SKB_CB(skb)->dccpd_ack_seq);

	}



	/* Step 2:

	 *	Look up flow ID in table and get corresponding socket */

lookup:

	sk = __inet_lookup_skb(&dccp_hashinfo, skb,

			       dh->dccph_sport, dh->dccph_dport);

	/*

	 * Step 2:

	 *	If no socket ...

	 */

	if (sk == NULL) {

	if (!sk) {

		dccp_pr_debug("failed to look up flow ID in table and "

			      "get corresponding socket\n");

		goto no_dccp_socket;
@@ -830,8 +825,12 @@ static int dccp_v4_rcv(struct sk_buff *skb) 
		struct sock *nsk = NULL;



		sk = req->rsk_listener;

		if (sk->sk_state == DCCP_LISTEN)

		if (likely(sk->sk_state == DCCP_LISTEN)) {

			nsk = dccp_check_req(sk, skb, req);

		} else {

			inet_csk_reqsk_queue_drop(sk, req);

			goto lookup;

		}

		if (!nsk) {

			reqsk_put(req);

			goto discard_it;

net/dccp/ipv6.c

+7 −8
Original line number Diff line number Diff line
@@ -656,16 +656,11 @@ static int dccp_v6_rcv(struct sk_buff *skb) 
	else

		DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);



	/* Step 2:

	 *	Look up flow ID in table and get corresponding socket */

lookup:

	sk = __inet6_lookup_skb(&dccp_hashinfo, skb,

			        dh->dccph_sport, dh->dccph_dport,

				inet6_iif(skb));

	/*

	 * Step 2:

	 *	If no socket ...

	 */

	if (sk == NULL) {

	if (!sk) {

		dccp_pr_debug("failed to look up flow ID in table and "

			      "get corresponding socket\n");

		goto no_dccp_socket;
@@ -688,8 +683,12 @@ static int dccp_v6_rcv(struct sk_buff *skb) 
		struct sock *nsk = NULL;



		sk = req->rsk_listener;

		if (sk->sk_state == DCCP_LISTEN)

		if (likely(sk->sk_state == DCCP_LISTEN)) {

			nsk = dccp_check_req(sk, skb, req);

		} else {

			inet_csk_reqsk_queue_drop(sk, req);

			goto lookup;

		}

		if (!nsk) {

			reqsk_put(req);

			goto discard_it;

net/ipv4/tcp_ipv4.c

+6 −1
Original line number Diff line number Diff line
@@ -1572,6 +1572,7 @@ int tcp_v4_rcv(struct sk_buff *skb) 
	TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph);

	TCP_SKB_CB(skb)->sacked	 = 0;



lookup:

	sk = __inet_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest);

	if (!sk)

		goto no_tcp_socket;
@@ -1587,8 +1588,12 @@ process: 
		sk = req->rsk_listener;

		if (tcp_v4_inbound_md5_hash(sk, skb))

			goto discard_and_relse;

		if (sk->sk_state == TCP_LISTEN)

		if (likely(sk->sk_state == TCP_LISTEN)) {

			nsk = tcp_check_req(sk, skb, req, false);

		} else {

			inet_csk_reqsk_queue_drop(sk, req);

			goto lookup;

		}

		if (!nsk) {

			reqsk_put(req);

			goto discard_it;

net/ipv6/tcp_ipv6.c

+6 −1
Original line number Diff line number Diff line
@@ -1363,6 +1363,7 @@ static int tcp_v6_rcv(struct sk_buff *skb) 
	th = tcp_hdr(skb);

	hdr = ipv6_hdr(skb);



lookup:

	sk = __inet6_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest,

				inet6_iif(skb));

	if (!sk)
@@ -1382,8 +1383,12 @@ process: 
			reqsk_put(req);

			goto discard_it;

		}

		if (sk->sk_state == TCP_LISTEN)

		if (likely(sk->sk_state == TCP_LISTEN)) {

			nsk = tcp_check_req(sk, skb, req, false);

		} else {

			inet_csk_reqsk_queue_drop(sk, req);

			goto lookup;

		}

		if (!nsk) {

			reqsk_put(req);

			goto discard_it;

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