conntrack: Reset ct_state when entering a new zone.
When a new conntrack zone is entered, the ct_state field is zeroed in
order to avoid using state information from different zones.
One such scenario is when a packet is double NATed. Assuming two zones
and 3 flows performing the following actions in order on the packet:
1. ct(zone=5,nat), recirc
2. ct(zone=1), recirc
3. ct(zone=1,nat)
If at step #1 the packet matches an existing NAT entry, it will get
translated and pkt->md.ct_state is set to CS_DST_NAT or CS_SRC_NAT.
At step #2 the new tuple might match an existing connection and
pkt->md.ct_zone is set to 1.
If at step #3 the packet matches an existing NAT entry in zone 1,
handle_nat() will be called to perform the translation but it will
return early because the packet's zone matches the conntrack zone and
the ct_state field still contains CS_DST_NAT or CS_SRC_NAT from the
translations in zone 5.
In order to reliably detect when a packet enters a new conntrack zone
we also need to make sure that the pkt->md.ct_zone is properly
initialized if pkt->md.ct_state is non-zero. This already happens for
most cases. The only exception is when matched conntrack connection is
of type CT_CONN_TYPE_UN_NAT and the master connection is missing. To
cover this path we now call write_ct_md() in that case too. Remove
setting the CS_TRACKED flag as in this case as it will be done by the
new call to write_ct_md().
projects / mirror_ovs.git / commit