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Install a REJECT rule for nodeport with no backend #43415

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Mar 21, 2017
Merged

Install a REJECT rule for nodeport with no backend #43415

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17 changes: 17 additions & 0 deletions pkg/proxy/iptables/proxier.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1108,6 +1108,21 @@ func (proxier *Proxier) syncProxyRules() {
// Currently we only create it for loadbalancers (#33586).
writeLine(natRules, append(args, "-j", string(svcXlbChain))...)
}

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We could do the "no endpoints" check before writing the MARK/SVC or XLB rules. But I presume we want to keep the rules less volatile?

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I have an idea for future refactoring that will make this nice, so I made the smallest change I could.

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You're saying you have a cunning plan? 👍

// If the service has no endpoints then reject packets. The filter
// table doesn't currently have the same per-service structure that
// the nat table does, so we just stick this into the kube-services
// chain.
if len(proxier.endpointsMap[svcName]) == 0 {
writeLine(filterRules,
"-A", string(kubeServicesChain),
"-m", "comment", "--comment", fmt.Sprintf(`"%s has no endpoints"`, svcName.String()),
"-m", "addrtype", "--dst-type", "LOCAL",
"-m", protocol, "-p", protocol,
"--dport", fmt.Sprintf("%d", svcInfo.nodePort),
"-j", "REJECT",
)
}
}

// If the service has no endpoints then reject packets.
Expand All @@ -1123,6 +1138,8 @@ func (proxier *Proxier) syncProxyRules() {
continue
}

// From here on, we assume there are active endpoints.

// Generate the per-endpoint chains. We do this in multiple passes so we
// can group rules together.
// These two slices parallel each other - keep in sync
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19 changes: 19 additions & 0 deletions pkg/proxy/iptables/proxier_test.go
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Expand Up @@ -694,6 +694,25 @@ func TestNodePort(t *testing.T) {
}
}

func TestNodePortReject(t *testing.T) {
ipt := iptablestest.NewFake()
fp := NewFakeProxier(ipt)
svcName := "svc1"
svcIP := net.IPv4(10, 20, 30, 41)

svc := proxy.ServicePortName{NamespacedName: types.NamespacedName{Namespace: "ns1", Name: svcName}, Port: "p80"}
svcInfo := newFakeServiceInfo(svc, svcIP, 80, api.ProtocolTCP, false)
svcInfo.nodePort = 3001
fp.serviceMap[svc] = svcInfo

fp.syncProxyRules()

kubeSvcRules := ipt.GetRules(string(kubeServicesChain))
if !hasJump(kubeSvcRules, iptablestest.Reject, svcIP.String(), 3001) {
errorf(fmt.Sprintf("Failed to find a %v rule for service %v with no endpoints", iptablestest.Reject, svcName), kubeSvcRules, t)
}
}

func strPtr(s string) *string {
return &s
}
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