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Date: Tue, 13 Oct 2015 17:12:54 -0700
From: Eric Dumazet <eric.dumazet@...il.com>
To: David Miller <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>
Subject: [PATCH net-next] tcp/dccp: fix behavior of stale SYN_RECV request
sockets
From: Eric Dumazet <edumazet@...gle.com>
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: 079096f103fa ("tcp/dccp: install syn_recv requests into ehash table")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
net/dccp/ipv4.c | 15 +++++++--------
net/dccp/ipv6.c | 15 +++++++--------
net/ipv4/tcp_ipv4.c | 7 ++++++-
net/ipv6/tcp_ipv6.c | 7 ++++++-
4 files changed, 26 insertions(+), 18 deletions(-)
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index 8e99681c8189d82e3e5f6a3c6089b103c0df2ca3..0dcf1963b323db7c7501dd58292795ee62fc0736 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -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;
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index aed314f8c7c60b00191aabc42c733f02304b18b0..68831931b1fe63a46031fe3324f8a0546f330236 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -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;
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index ddb198392c7fd9be24d62a5d87da051b86cc8c55..1ff0923df7153d37f153fb0fa100a88cdeef0509 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -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;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 2887c8474b650468a76919fe9d25aff43361e1ba..7ce1c57199d13ac4b5d20ab47a32471493322edd 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -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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