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tcp/dccp: fix behavior of stale SYN_RECV request sockets

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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: 079096f103 ("tcp/dccp: install syn_recv requests into ehash table")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2015-10-13 17:12:54 -07:00 • committed by David S. Miller
parent bbb300eb97
commit 4bdc3d6614
4 changed files with 26 additions and 18 deletions
Download patch file Download diff file Expand all files Collapse all files

7
net/ipv4/tcp_ipv4.c
View file

@ -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;