From: Xin Long <lucien.xin@gmail.com>
To: Sriram Yagnaraman <sriram.yagnaraman@est.tech>
Cc: network dev <netdev@vger.kernel.org>,
"netfilter-devel@vger.kernel.org"
<netfilter-devel@vger.kernel.org>,
"linux-sctp@vger.kernel.org" <linux-sctp@vger.kernel.org>,
"davem@davemloft.net" <davem@davemloft.net>,
"kuba@kernel.org" <kuba@kernel.org>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>,
Pablo Neira Ayuso <pablo@netfilter.org>,
Jozsef Kadlecsik <kadlec@netfilter.org>,
Florian Westphal <fw@strlen.de>,
Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Subject: Re: [PATCH nf] netfilter: set default timeout to 3 secs for sctp shutdown send and recv state
Date: Tue, 15 Aug 2023 10:01:41 -0400 [thread overview]
Message-ID: <CADvbK_eHOU1RCRxNFYTZ9GOwkeTFmSxtzmnGqUhOh-gh82Z8nQ@mail.gmail.com> (raw)
In-Reply-To: <DBBP189MB1433FD875F0B6859676196489514A@DBBP189MB1433.EURP189.PROD.OUTLOOK.COM>
On Tue, Aug 15, 2023 at 3:59 AM Sriram Yagnaraman
<sriram.yagnaraman@est.tech> wrote:
>
>
>
> > -----Original Message-----
> > From: Xin Long <lucien.xin@gmail.com>
> > Sent: Sunday, 13 August 2023 18:56
> > To: network dev <netdev@vger.kernel.org>; netfilter-devel@vger.kernel.org;
> > linux-sctp@vger.kernel.org
> > Cc: davem@davemloft.net; kuba@kernel.org; Eric Dumazet
> > <edumazet@google.com>; Paolo Abeni <pabeni@redhat.com>; Pablo Neira
> > Ayuso <pablo@netfilter.org>; Jozsef Kadlecsik <kadlec@netfilter.org>; Florian
> > Westphal <fw@strlen.de>; Marcelo Ricardo Leitner
> > <marcelo.leitner@gmail.com>
> > Subject: [PATCH nf] netfilter: set default timeout to 3 secs for sctp shutdown
> > send and recv state
> >
> > 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>
> > ---
> > net/netfilter/nf_conntrack_proto_sctp.c | 6 +++---
> > 1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/net/netfilter/nf_conntrack_proto_sctp.c
> > b/net/netfilter/nf_conntrack_proto_sctp.c
> > index 91eacc9b0b98..b6bcc8f2f46b 100644
> > --- a/net/netfilter/nf_conntrack_proto_sctp.c
> > +++ b/net/netfilter/nf_conntrack_proto_sctp.c
> > @@ -49,8 +49,8 @@ static const unsigned int
> > sctp_timeouts[SCTP_CONNTRACK_MAX] = {
> > [SCTP_CONNTRACK_COOKIE_WAIT] = 3 SECS,
> > [SCTP_CONNTRACK_COOKIE_ECHOED] = 3 SECS,
> > [SCTP_CONNTRACK_ESTABLISHED] = 210 SECS,
> > - [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,
> > };
> > @@ -105,7 +105,7 @@ static const u8
> > sctp_conntracks[2][11][SCTP_CONNTRACK_MAX] = {
> > {
> > /* ORIGINAL */
> > /* sNO, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS */
> > -/* init */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sCW},
> > +/* init */ {sCL, sCL, sCW, sCE, sES, sCL, sCL, sSA, sCW},
> > /* init_ack */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sCL},
> > /* abort */ {sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL},
> > /* shutdown */ {sCL, sCL, sCW, sCE, sSS, sSS, sSR, sSA, sCL},
> > --
> > 2.39.1
>
> FWIW, I like this patch. Should Documentation/networking/nf_conntrack-sysctl.rst be updated to reflect the new timeout values?
Good catch, will post v2 with the 0.3 -> 3 change in nf_conntrack-sysctl.rst.
Thanks for the review.
next prev parent reply other threads:[~2023-08-15 14:03 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-13 16:55 [PATCH nf] netfilter: set default timeout to 3 secs for sctp shutdown send and recv state Xin Long
2023-08-15 7:59 ` Sriram Yagnaraman
2023-08-15 14:01 ` Xin Long [this message]
2023-08-15 7:59 ` Simon Horman
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