From d7ee3519042798be6224e97f259ed47a63da4620 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Michal=20Kube=C4=8Dek?= Date: Fri, 17 Jul 2015 16:17:56 +0200 Subject: netfilter: nf_ct_sctp: minimal multihoming support Currently nf_conntrack_proto_sctp module handles only packets between primary addresses used to establish the connection. Any packets between secondary addresses are classified as invalid so that usual firewall configurations drop them. Allowing HEARTBEAT and HEARTBEAT-ACK chunks to establish a new conntrack would allow traffic between secondary addresses to pass through. A more sophisticated solution based on the addresses advertised in the initial handshake (and possibly also later dynamic address addition and removal) would be much harder to implement. Moreover, in general we cannot assume to always see the initial handshake as it can be routed through a different path. The patch adds two new conntrack states: SCTP_CONNTRACK_HEARTBEAT_SENT - a HEARTBEAT chunk seen but not acked SCTP_CONNTRACK_HEARTBEAT_ACKED - a HEARTBEAT acked by HEARTBEAT-ACK State transition rules: - HEARTBEAT_SENT responds to usual chunks the same way as NONE (so that the behaviour changes as little as possible) - HEARTBEAT_ACKED responds to usual chunks the same way as ESTABLISHED does, except the resulting state is HEARTBEAT_ACKED rather than ESTABLISHED - previously existing states except NONE are preserved when HEARTBEAT or HEARTBEAT-ACK is seen - NONE (in the initial direction) changes to HEARTBEAT_SENT on HEARTBEAT and to CLOSED on HEARTBEAT-ACK - HEARTBEAT_SENT changes to HEARTBEAT_ACKED on HEARTBEAT-ACK in the reply direction - HEARTBEAT_SENT and HEARTBEAT_ACKED are preserved on HEARTBEAT and HEARTBEAT-ACK otherwise Normally, vtag is set from the INIT chunk for the reply direction and from the INIT-ACK chunk for the originating direction (i.e. each of these defines vtag value for the opposite direction). For secondary conntracks, we can't rely on seeing INIT/INIT-ACK and even if we have seen them, we would need to connect two different conntracks. Therefore simplified logic is applied: vtag of first packet in each direction (HEARTBEAT in the originating and HEARTBEAT-ACK in reply direction) is saved and all following packets in that direction are compared with this saved value. While INIT and INIT-ACK define vtag for the opposite direction, vtags extracted from HEARTBEAT and HEARTBEAT-ACK are always for their direction. Default timeout values for new states are HEARTBEAT_SENT: 30 seconds (default hb_interval) HEARTBEAT_ACKED: 210 seconds (hb_interval * path_max_retry + max_rto) (We cannot expect to see the shutdown sequence so that, unlike ESTABLISHED, the HEARTBEAT_ACKED timeout shouldn't be too long.) Signed-off-by: Michal Kubecek Signed-off-by: Pablo Neira Ayuso --- include/uapi/linux/netfilter/nf_conntrack_sctp.h | 2 ++ include/uapi/linux/netfilter/nfnetlink_cttimeout.h | 2 ++ 2 files changed, 4 insertions(+) (limited to 'include/uapi') diff --git a/include/uapi/linux/netfilter/nf_conntrack_sctp.h b/include/uapi/linux/netfilter/nf_conntrack_sctp.h index ceeefe6681b5..ed4e776e1242 100644 --- a/include/uapi/linux/netfilter/nf_conntrack_sctp.h +++ b/include/uapi/linux/netfilter/nf_conntrack_sctp.h @@ -13,6 +13,8 @@ enum sctp_conntrack { SCTP_CONNTRACK_SHUTDOWN_SENT, SCTP_CONNTRACK_SHUTDOWN_RECD, SCTP_CONNTRACK_SHUTDOWN_ACK_SENT, + SCTP_CONNTRACK_HEARTBEAT_SENT, + SCTP_CONNTRACK_HEARTBEAT_ACKED, SCTP_CONNTRACK_MAX }; diff --git a/include/uapi/linux/netfilter/nfnetlink_cttimeout.h b/include/uapi/linux/netfilter/nfnetlink_cttimeout.h index 1ab0b97b3a1e..f2c10dc140d6 100644 --- a/include/uapi/linux/netfilter/nfnetlink_cttimeout.h +++ b/include/uapi/linux/netfilter/nfnetlink_cttimeout.h @@ -92,6 +92,8 @@ enum ctattr_timeout_sctp { CTA_TIMEOUT_SCTP_SHUTDOWN_SENT, CTA_TIMEOUT_SCTP_SHUTDOWN_RECD, CTA_TIMEOUT_SCTP_SHUTDOWN_ACK_SENT, + CTA_TIMEOUT_SCTP_HEARTBEAT_SENT, + CTA_TIMEOUT_SCTP_HEARTBEAT_ACKED, __CTA_TIMEOUT_SCTP_MAX }; #define CTA_TIMEOUT_SCTP_MAX (__CTA_TIMEOUT_SCTP_MAX - 1) -- cgit v1.2.3