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authorMarcelo Leitner <mleitner@redhat.com>2014-10-13 13:09:28 -0300
committerPablo Neira Ayuso <pablo@netfilter.org>2014-10-22 14:12:50 +0200
commite37ad9fd636071e45368d1d9cc3b7b421281ce7f (patch)
treee44d86031de19e16ee5632d866178c82ce0d5ced /net
parent7c1c97d54f9bfc810908d3903cb8bcacf734df18 (diff)
netfilter: nf_conntrack: allow server to become a client in TW handling
When a port that was used to listen for inbound connections gets closed and reused for outgoing connections (like rsh ends up doing for stderr flow), current we may reject the SYN/ACK packet for the new connection because tcp_conntracks states forbirds a port to become a client while there is still a TIME_WAIT entry in there for it. As TCP may expire the TIME_WAIT socket in 60s and conntrack's timeout for it is 120s, there is a ~60s window that the application can end up opening a port that conntrack will end up blocking. This patch fixes this by simply allowing such state transition: if we see a SYN, in TIME_WAIT state, on REPLY direction, move it to sSS. Note that the rest of the code already handles this situation, more specificly in tcp_packet(), first switch clause. Signed-off-by: Marcelo Ricardo Leitner <mleitner@redhat.com> Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/nf_conntrack_proto_tcp.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
index 44d1ea32570a..d87b6423ffb2 100644
--- a/net/netfilter/nf_conntrack_proto_tcp.c
+++ b/net/netfilter/nf_conntrack_proto_tcp.c
@@ -213,7 +213,7 @@ static const u8 tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = {
{
/* REPLY */
/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
-/*syn*/ { sIV, sS2, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sS2 },
+/*syn*/ { sIV, sS2, sIV, sIV, sIV, sIV, sIV, sSS, sIV, sS2 },
/*
* sNO -> sIV Never reached.
* sSS -> sS2 Simultaneous open
@@ -223,7 +223,7 @@ static const u8 tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = {
* sFW -> sIV
* sCW -> sIV
* sLA -> sIV
- * sTW -> sIV Reopened connection, but server may not do it.
+ * sTW -> sSS Reopened connection, but server may have switched role
* sCL -> sIV
*/
/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */