The nftables implementation made use of concatenation of ranges when
creating the set "firewall-allow", but the support was not available
before kernel 5.6. Therefore, nftables mode couldn't run on earlier
kernels, while 5.4 is still widely used.
An alternative of concatenation of ranges is to create a separate
firewall chain for every service port that needs firewalling, and jump
to the service's firewall chain from the common firewall chain via a
rule with vmap.
Renaming from "firewall" to "firewall-ips" is required when changing the
set to the map to support existing clusters to upgrade, otherwise it
would fail to create the map. Besides, "firewall-ips" corresponds to the
"service-ips" map, later we can add use "firewall-nodeports" if it's
determined that NodePort traffic should be subject to
LoadBalancerSourceRanges.
Signed-off-by: Quan Tian <qtian@vmware.com>
And update most of the comments to refer to "nftables" rather than
"iptables" (even though it doesn't actually do any nftables updating
at this point).
For now the proxy also internally creates a
utiliptablestesting.FakeIPTables to keep the existing sync code
compiling.
(It is confusing, but allowed, to have distinct "KUBE-SERVICES" chains
in "nat" and "filter" in iptables, but in nftables the "type nat" and
"type filter" chains end up in the same table, so we'll need different
names for the two.)
Change the svcPortInfo and endpointInfo fields to string rather than
utiliptables.Chain, and various fixups from there.
Also use a proper set for activeNATChains, and fix the capitalization
of endpointInfo.chainName.
