in network policies
- enhance selectorSpec to accomodate both pod and namespace selectors
- enhance analysePolicy to handle policies with both selectors
Fixes#3312
When using ipBlock in Ingress policy, one should be aware
that source IP addr of packet destined to Pod in many cases
is mangled, see docs/k8s-src-ip.md for the cases.
However, the mangling in some cases can be prevented with
setting externalTrafficPolicy to Local.
Otherwise, the same ipBlock ipset can be used among different namespaces which
results in panic as refcounting of ipsets happens only per namespace, so
npc will try to create the same ipset twice.
dstSelector becomes ambiguous once we introduce the egress.
So, from now on, we call selector a target selector if it selects
pods to which a netpol applies (aka NetworkPolicySpec.podSelector).
This ensures two rules with the same rulespec but of different
policyType will end up having different keys.
Sharing the same key would prevent from provisioning the rules.
The following rules are provisioned by weave-npc:
-A WEAVE-NPC-EGRESS -m state --state RELATED,ESTABLISHED -j RETURN
-A WEAVE-NPC-EGRESS -m set ! --match-set weave-local-pods src -j RETURN
-A WEAVE-NPC-EGRESS -d 224.0.0.0/4 -j RETURN
-A WEAVE-NPC-EGRESS -m state --state NEW -j WEAVE-NPC-EGRESS-DEFAULT
-A WEAVE-NPC-EGRESS -m state --state NEW -m mark ! --mark 0x40000/0x40000 -j WEAVE-NPC-EGRESS-CUSTOM
-A WEAVE-NPC-EGRESS -m state --state NEW -m mark ! --mark 0x40000/0x40000 -j NFLOG --nflog-group 86
-A WEAVE-NPC-EGRESS -m mark ! --mark 0x40000/0x40000 -j DROP
-A WEAVE-NPC-EGRESS-CUSTOM <rulespec> -j MARK --set-xmark 0x40000/0x40000
-A WEAVE-NPC-EGRESS-CUSTOM <rulespec> -j RETURN
-A WEAVE-NPC-EGRESS-DEFAULT <rulespec> -j MARK --set-xmark 0x40000/0x40000
-A WEAVE-NPC-EGRESS-DEFAULT <rulespec> -j RETURN
For each rule we create two (mark and return). We cannot just accept
a packet if it matches any rule, as a packet might need to traverse
the ingress npc as well which happens later in the chain (in some cases
we cannot detect whether packet is ingress or egress, so we need to
check both chains).
There was a bug in the npc analyser when adding a netpol with
dstSelector == srcSelector. The analyser was overwriting
dstSelector with srcSelector which resulted in Pod selected
by dstSelector not being removed from a corresponding
"default-allow" ipset.
This applies only to non-legacy netpols.
Murali Reddy