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Fix connection resets during firewall sync (#807)

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For very busy tcp connections there is a small possibility to receive
a TCP RST during the iptables sync.

A default `REJECT` rule is chronologically added before the allow-`RELATED,ESTABLISHED` rule for ingress and
egress connections.
In between of the creation of these two rules a connection reset can happen for already established connections.

This commits swaps the order of rule insertion.
This commit is contained in:
Boris Djurdjevic 2019-12-09 17:07:27 +01:00 committed by Murali Reddy
parent 3a0da2bf9a
commit 8bcd166c4c
1 changed files with 31 additions and 31 deletions
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62
pkg/controllers/netpol/network_policy_controller.go
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@ -748,6 +748,20 @@ func (npc *NetworkPolicyController) syncPodFirewallChains(version string) (map[s
}
}
// ensure statefull firewall, that permits return traffic for the traffic originated by the pod
comment = "rule for stateful firewall for pod"
args = []string{"-m", "comment", "--comment", comment, "-m", "conntrack", "--ctstate", "RELATED,ESTABLISHED", "-j", "ACCEPT"}
exists, err = iptablesCmdHandler.Exists("filter", podFwChainName, args...)
if err != nil {
return nil, fmt.Errorf("Failed to run iptables command: %s", err.Error())
}
if !exists {
err := iptablesCmdHandler.Insert("filter", podFwChainName, 1, args...)
if err != nil {
return nil, fmt.Errorf("Failed to run iptables command: %s", err.Error())
}
}
// ensure there is rule in filter table and FORWARD chain to jump to pod specific firewall chain
// this rule applies to the traffic getting routed (coming for other node pods)
comment = "rule to jump traffic destined to POD name:" + pod.name + " namespace: " + pod.namespace +
@ -803,20 +817,6 @@ func (npc *NetworkPolicyController) syncPodFirewallChains(version string) (map[s
if err != nil {
return nil, fmt.Errorf("Failed to run iptables command: %s", err.Error())
}
// ensure statefull firewall, that permits return traffic for the traffic originated by the pod
comment = "rule for stateful firewall for pod"
args = []string{"-m", "comment", "--comment", comment, "-m", "conntrack", "--ctstate", "RELATED,ESTABLISHED", "-j", "ACCEPT"}
exists, err = iptablesCmdHandler.Exists("filter", podFwChainName, args...)
if err != nil {
return nil, fmt.Errorf("Failed to run iptables command: %s", err.Error())
}
if !exists {
err := iptablesCmdHandler.Insert("filter", podFwChainName, 1, args...)
if err != nil {
return nil, fmt.Errorf("Failed to run iptables command: %s", err.Error())
}
}
}
// loop through the pods running on the node which egress network policies to be applied
@ -859,12 +859,26 @@ func (npc *NetworkPolicyController) syncPodFirewallChains(version string) (map[s
}
}
// ensure statefull firewall, that permits return traffic for the traffic originated by the pod
comment := "rule for stateful firewall for pod"
args := []string{"-m", "comment", "--comment", comment, "-m", "conntrack", "--ctstate", "RELATED,ESTABLISHED", "-j", "ACCEPT"}
exists, err := iptablesCmdHandler.Exists("filter", podFwChainName, args...)
if err != nil {
return nil, fmt.Errorf("Failed to run iptables command: %s", err.Error())
}
if !exists {
err := iptablesCmdHandler.Insert("filter", podFwChainName, 1, args...)
if err != nil {
return nil, fmt.Errorf("Failed to run iptables command: %s", err.Error())
}
}
// ensure there is rule in filter table and FORWARD chain to jump to pod specific firewall chain
// this rule applies to the traffic getting routed (coming for other node pods)
comment := "rule to jump traffic from POD name:" + pod.name + " namespace: " + pod.namespace +
comment = "rule to jump traffic from POD name:" + pod.name + " namespace: " + pod.namespace +
" to chain " + podFwChainName
args := []string{"-m", "comment", "--comment", comment, "-s", pod.ip, "-j", podFwChainName}
exists, err := iptablesCmdHandler.Exists("filter", "FORWARD", args...)
args = []string{"-m", "comment", "--comment", comment, "-s", pod.ip, "-j", podFwChainName}
exists, err = iptablesCmdHandler.Exists("filter", "FORWARD", args...)
if err != nil {
return nil, fmt.Errorf("Failed to run iptables command: %s", err.Error())
}
@ -901,20 +915,6 @@ func (npc *NetworkPolicyController) syncPodFirewallChains(version string) (map[s
if err != nil {
return nil, fmt.Errorf("Failed to run iptables command: %s", err.Error())
}
// ensure statefull firewall, that permits return traffic for the traffic originated by the pod
comment = "rule for stateful firewall for pod"
args = []string{"-m", "comment", "--comment", comment, "-m", "conntrack", "--ctstate", "RELATED,ESTABLISHED", "-j", "ACCEPT"}
exists, err = iptablesCmdHandler.Exists("filter", podFwChainName, args...)
if err != nil {
return nil, fmt.Errorf("Failed to run iptables command: %s", err.Error())
}
if !exists {
err := iptablesCmdHandler.Insert("filter", podFwChainName, 1, args...)
if err != nil {
return nil, fmt.Errorf("Failed to run iptables command: %s", err.Error())
}
}
}
return activePodFwChains, nil