[PATCH 5.16 205/227] netfilter: conntrack: dont refresh sctp entries in closed state

Greg Kroah-Hartman
2022-02-21T10:09:38Z

From: Florian Westphal <fw@strlen.de>

[ Upstream commit 77b337196a9d87f3d6bb9b07c0436ecafbffda1e ]

Vivek Thrivikraman reported:
An SCTP server application which is accessed continuously by client
application.
When the session disconnects the client retries to establish a connection.
After restart of SCTP server application the session is not established
because of stale conntrack entry with connection state CLOSED as below.

(removing this entry manually established new connection):

sctp 9 CLOSED src=10.141.189.233 [..] [ASSURED]

Just skip timeout update of closed entries, we don't want them to
stay around forever.

Reported-and-tested-by: Vivek Thrivikraman <vivek.thrivikraman@est.tech>
Closes: https://bugzilla.netfilter.org/show_bug.cgi?id=1579
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/netfilter/nf_conntrack_proto_sctp.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/net/netfilter/nf_conntrack_proto_sctp.c b/net/netfilter/nf_conntrack_proto_sctp.c
index 2394238d01c91..5a936334b517a 100644
--- a/net/netfilter/nf_conntrack_proto_sctp.c
+++ b/net/netfilter/nf_conntrack_proto_sctp.c
@@ -489,6 +489,15 @@ int nf_conntrack_sctp_packet(struct nf_conn *ct,
pr_debug("Setting vtag %x for dir %d\n",
ih->init_tag, !dir);
ct->proto.sctp.vtag[!dir] = ih->init_tag;
+
+ /* don't renew timeout on init retransmit so
+ * port reuse by client or NAT middlebox cannot
+ * keep entry alive indefinitely (incl. nat info).
+ */
+ if (new_state == SCTP_CONNTRACK_CLOSED &&
+ old_state == SCTP_CONNTRACK_CLOSED &&
+ nf_ct_is_confirmed(ct))
+ ignore = true;
}

ct->proto.sctp.state = new_state;
--
2.34.1