4.14-stable review patch. If anyone has any objections, please let me know.
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From: Xin Long lucien.xin@gmail.com
commit 9bfab6d23a2865966a4f89a96536fbf23f83bc8c upstream.
In SCTP protocol, it is using the same timer (T2 timer) for SHUTDOWN and SHUTDOWN_ACK retransmission. However in sctp conntrack the default timeout value for SCTP_CONNTRACK_SHUTDOWN_ACK_SENT state is 3 secs while it's 300 msecs for SCTP_CONNTRACK_SHUTDOWN_SEND/RECV state.
As Paolo Valerio noticed, this might cause unwanted expiration of the ct entry. In my test, with 1s tc netem delay set on the NAT path, after the SHUTDOWN is sent, the sctp ct entry enters SCTP_CONNTRACK_SHUTDOWN_SEND state. However, due to 300ms (too short) delay, when the SHUTDOWN_ACK is sent back from the peer, the sctp ct entry has expired and been deleted, and then the SHUTDOWN_ACK has to be dropped.
Also, it is confusing these two sysctl options always show 0 due to all timeout values using sec as unit:
net.netfilter.nf_conntrack_sctp_timeout_shutdown_recd = 0 net.netfilter.nf_conntrack_sctp_timeout_shutdown_sent = 0
This patch fixes it by also using 3 secs for sctp shutdown send and recv state in sctp conntrack, which is also RTO.initial value in SCTP protocol.
Note that the very short time value for SCTP_CONNTRACK_SHUTDOWN_SEND/RECV was probably used for a rare scenario where SHUTDOWN is sent on 1st path but SHUTDOWN_ACK is replied on 2nd path, then a new connection started immediately on 1st path. So this patch also moves from SHUTDOWN_SEND/RECV to CLOSE when receiving INIT in the ORIGINAL direction.
Fixes: 9fb9cbb1082d ("[NETFILTER]: Add nf_conntrack subsystem.") Reported-by: Paolo Valerio pvalerio@redhat.com Signed-off-by: Xin Long lucien.xin@gmail.com Reviewed-by: Simon Horman horms@kernel.org Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/netfilter/nf_conntrack_proto_sctp.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/net/netfilter/nf_conntrack_proto_sctp.c +++ b/net/netfilter/nf_conntrack_proto_sctp.c @@ -57,8 +57,8 @@ static unsigned int sctp_timeouts[SCTP_C [SCTP_CONNTRACK_COOKIE_WAIT] = 3 SECS, [SCTP_CONNTRACK_COOKIE_ECHOED] = 3 SECS, [SCTP_CONNTRACK_ESTABLISHED] = 5 DAYS, - [SCTP_CONNTRACK_SHUTDOWN_SENT] = 300 SECS / 1000, - [SCTP_CONNTRACK_SHUTDOWN_RECD] = 300 SECS / 1000, + [SCTP_CONNTRACK_SHUTDOWN_SENT] = 3 SECS, + [SCTP_CONNTRACK_SHUTDOWN_RECD] = 3 SECS, [SCTP_CONNTRACK_SHUTDOWN_ACK_SENT] = 3 SECS, [SCTP_CONNTRACK_HEARTBEAT_SENT] = 30 SECS, [SCTP_CONNTRACK_HEARTBEAT_ACKED] = 210 SECS, @@ -116,7 +116,7 @@ static const u8 sctp_conntracks[2][11][S { /* ORIGINAL */ /* sNO, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS, sHA */ -/* init */ {sCW, sCW, sCW, sCE, sES, sSS, sSR, sSA, sCW, sHA}, +/* init */ {sCW, sCW, sCW, sCE, sES, sCL, sCL, sSA, sCW, sHA}, /* init_ack */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sCL, sHA}, /* abort */ {sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL}, /* shutdown */ {sCL, sCL, sCW, sCE, sSS, sSS, sSR, sSA, sCL, sSS},