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269 lines
12 KiB
Go
269 lines
12 KiB
Go
// Apache License v2.0 (copyright Cloud Native Labs & Rancher Labs)
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// - modified from https://github.com/cloudnativelabs/kube-router/blob/73b1b03b32c5755b240f6c077bb097abe3888314/pkg/controllers/netpol/pod.go
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// +build !windows
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package netpol
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import (
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"crypto/sha256"
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"encoding/base32"
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"strings"
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api "k8s.io/api/core/v1"
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"k8s.io/client-go/tools/cache"
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"k8s.io/klog/v2"
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)
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func (npc *NetworkPolicyController) newPodEventHandler() cache.ResourceEventHandler {
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return cache.ResourceEventHandlerFuncs{
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AddFunc: func(obj interface{}) {
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if podObj, ok := obj.(*api.Pod); ok {
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// If the pod isn't yet actionable there is no action to take here anyway, so skip it. When it becomes
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// actionable, we'll get an update below.
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if isNetPolActionable(podObj) {
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npc.OnPodUpdate(obj)
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}
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}
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},
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UpdateFunc: func(oldObj, newObj interface{}) {
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var newPodObj, oldPodObj *api.Pod
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var ok bool
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// If either of these objects are not pods, quit now
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if newPodObj, ok = newObj.(*api.Pod); !ok {
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return
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}
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if oldPodObj, ok = oldObj.(*api.Pod); !ok {
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return
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}
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// We don't check isNetPolActionable here, because if it is transitioning in or out of the actionable state
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// we want to run the full sync so that it can be added or removed from the existing network policy of the host
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// For the network policies, we are only interested in some changes, most pod changes aren't relevant to network policy
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if isPodUpdateNetPolRelevant(oldPodObj, newPodObj) {
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npc.OnPodUpdate(newObj)
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}
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},
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DeleteFunc: func(obj interface{}) {
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npc.handlePodDelete(obj)
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},
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}
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}
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// OnPodUpdate handles updates to pods from the Kubernetes api server
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func (npc *NetworkPolicyController) OnPodUpdate(obj interface{}) {
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pod := obj.(*api.Pod)
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klog.V(2).Infof("Received update to pod: %s/%s", pod.Namespace, pod.Name)
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npc.RequestFullSync()
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}
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func (npc *NetworkPolicyController) handlePodDelete(obj interface{}) {
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pod, ok := obj.(*api.Pod)
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if !ok {
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tombstone, ok := obj.(cache.DeletedFinalStateUnknown)
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if !ok {
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klog.Errorf("unexpected object type: %v", obj)
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return
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}
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if pod, ok = tombstone.Obj.(*api.Pod); !ok {
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klog.Errorf("unexpected object type: %v", obj)
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return
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}
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}
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klog.V(2).Infof("Received pod: %s/%s delete event", pod.Namespace, pod.Name)
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npc.RequestFullSync()
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}
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func (npc *NetworkPolicyController) syncPodFirewallChains(networkPoliciesInfo []networkPolicyInfo, version string) (map[string]bool, error) {
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activePodFwChains := make(map[string]bool)
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dropUnmarkedTrafficRules := func(podName, podNamespace, podFwChainName string) error {
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// add rule to log the packets that will be dropped due to network policy enforcement
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comment := "\"rule to log dropped traffic POD name:" + podName + " namespace: " + podNamespace + "\""
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args := []string{"-A", podFwChainName, "-m", "comment", "--comment", comment, "-m", "mark", "!", "--mark", "0x10000/0x10000", "-j", "NFLOG", "--nflog-group", "100", "-m", "limit", "--limit", "10/minute", "--limit-burst", "10", "\n"}
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// This used to be AppendUnique when we were using iptables directly, this checks to make sure we didn't drop unmarked for this chain already
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if strings.Contains(npc.filterTableRules.String(), strings.Join(args, " ")) {
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return nil
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}
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npc.filterTableRules.WriteString(strings.Join(args, " "))
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// add rule to DROP if no applicable network policy permits the traffic
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comment = "\"rule to REJECT traffic destined for POD name:" + podName + " namespace: " + podNamespace + "\""
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args = []string{"-A", podFwChainName, "-m", "comment", "--comment", comment, "-m", "mark", "!", "--mark", "0x10000/0x10000", "-j", "REJECT", "\n"}
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npc.filterTableRules.WriteString(strings.Join(args, " "))
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// reset mark to let traffic pass through rest of the chains
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args = []string{"-A", podFwChainName, "-j", "MARK", "--set-mark", "0/0x10000", "\n"}
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npc.filterTableRules.WriteString(strings.Join(args, " "))
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return nil
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}
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// loop through the pods running on the node
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allLocalPods, err := npc.getLocalPods(npc.nodeIP.String())
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if err != nil {
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return nil, err
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}
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for _, pod := range *allLocalPods {
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// ensure pod specific firewall chain exist for all the pods that need ingress firewall
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podFwChainName := podFirewallChainName(pod.namespace, pod.name, version)
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npc.filterTableRules.WriteString(":" + podFwChainName + "\n")
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activePodFwChains[podFwChainName] = true
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// setup rules to run through applicable ingress/egress network policies for the pod
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npc.setupPodNetpolRules(&pod, podFwChainName, networkPoliciesInfo, version)
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// setup rules to intercept inbound traffic to the pods
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npc.interceptPodInboundTraffic(&pod, podFwChainName)
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// setup rules to intercept inbound traffic to the pods
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npc.interceptPodOutboundTraffic(&pod, podFwChainName)
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err = dropUnmarkedTrafficRules(pod.name, pod.namespace, podFwChainName)
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if err != nil {
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return nil, err
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}
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// set mark to indicate traffic from/to the pod passed network policies.
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// Mark will be checked to explicitly ACCEPT the traffic
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comment := "\"set mark to ACCEPT traffic that comply to network policies\""
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args := []string{"-A", podFwChainName, "-m", "comment", "--comment", comment, "-j", "MARK", "--set-mark", "0x20000/0x20000", "\n"}
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npc.filterTableRules.WriteString(strings.Join(args, " "))
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}
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return activePodFwChains, nil
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}
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// setup rules to jump to applicable network policy chains for the traffic from/to the pod
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func (npc *NetworkPolicyController) setupPodNetpolRules(pod *podInfo, podFwChainName string, networkPoliciesInfo []networkPolicyInfo, version string) {
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hasIngressPolicy := false
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hasEgressPolicy := false
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// add entries in pod firewall to run through applicable network policies
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for _, policy := range networkPoliciesInfo {
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if _, ok := policy.targetPods[pod.ip]; !ok {
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continue
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}
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comment := "\"run through nw policy " + policy.name + "\""
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policyChainName := networkPolicyChainName(policy.namespace, policy.name, version)
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var args []string
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switch policy.policyType {
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case "both":
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hasIngressPolicy = true
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hasEgressPolicy = true
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args = []string{"-I", podFwChainName, "1", "-m", "comment", "--comment", comment, "-j", policyChainName, "\n"}
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case "ingress":
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hasIngressPolicy = true
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args = []string{"-I", podFwChainName, "1", "-d", pod.ip, "-m", "comment", "--comment", comment, "-j", policyChainName, "\n"}
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case "egress":
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hasEgressPolicy = true
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args = []string{"-I", podFwChainName, "1", "-s", pod.ip, "-m", "comment", "--comment", comment, "-j", policyChainName, "\n"}
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}
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npc.filterTableRules.WriteString(strings.Join(args, " "))
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}
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// if pod does not have any network policy which applies rules for pod's ingress traffic
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// then apply default network policy
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if !hasIngressPolicy {
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comment := "\"run through default ingress network policy chain\""
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args := []string{"-I", podFwChainName, "1", "-d", pod.ip, "-m", "comment", "--comment", comment, "-j", kubeDefaultNetpolChain, "\n"}
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npc.filterTableRules.WriteString(strings.Join(args, " "))
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}
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// if pod does not have any network policy which applies rules for pod's egress traffic
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// then apply default network policy
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if !hasEgressPolicy {
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comment := "\"run through default egress network policy chain\""
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args := []string{"-I", podFwChainName, "1", "-s", pod.ip, "-m", "comment", "--comment", comment, "-j", kubeDefaultNetpolChain, "\n"}
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npc.filterTableRules.WriteString(strings.Join(args, " "))
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}
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comment := "\"rule to permit the traffic traffic to pods when source is the pod's local node\""
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args := []string{"-I", podFwChainName, "1", "-m", "comment", "--comment", comment, "-m", "addrtype", "--src-type", "LOCAL", "-d", pod.ip, "-j", "ACCEPT", "\n"}
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npc.filterTableRules.WriteString(strings.Join(args, " "))
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// ensure statefull firewall that permits RELATED,ESTABLISHED traffic from/to the pod
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comment = "\"rule for stateful firewall for pod\""
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args = []string{"-I", podFwChainName, "1", "-m", "comment", "--comment", comment, "-m", "conntrack", "--ctstate", "RELATED,ESTABLISHED", "-j", "ACCEPT", "\n"}
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npc.filterTableRules.WriteString(strings.Join(args, " "))
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}
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func (npc *NetworkPolicyController) interceptPodInboundTraffic(pod *podInfo, podFwChainName string) {
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// ensure there is rule in filter table and FORWARD chain to jump to pod specific firewall chain
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// this rule applies to the traffic getting routed (coming for other node pods)
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comment := "\"rule to jump traffic destined to POD name:" + pod.name + " namespace: " + pod.namespace +
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" to chain " + podFwChainName + "\""
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args := []string{"-I", kubeForwardChainName, "1", "-m", "comment", "--comment", comment, "-d", pod.ip, "-j", podFwChainName + "\n"}
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npc.filterTableRules.WriteString(strings.Join(args, " "))
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// ensure there is rule in filter table and OUTPUT chain to jump to pod specific firewall chain
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// this rule applies to the traffic from a pod getting routed back to another pod on same node by service proxy
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args = []string{"-I", kubeOutputChainName, "1", "-m", "comment", "--comment", comment, "-d", pod.ip, "-j", podFwChainName + "\n"}
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npc.filterTableRules.WriteString(strings.Join(args, " "))
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// ensure there is rule in filter table and forward chain to jump to pod specific firewall chain
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// this rule applies to the traffic getting switched (coming for same node pods)
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comment = "\"rule to jump traffic destined to POD name:" + pod.name + " namespace: " + pod.namespace +
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" to chain " + podFwChainName + "\""
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args = []string{"-I", kubeForwardChainName, "1", "-m", "physdev", "--physdev-is-bridged",
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"-m", "comment", "--comment", comment,
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"-d", pod.ip,
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"-j", podFwChainName, "\n"}
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npc.filterTableRules.WriteString(strings.Join(args, " "))
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}
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// setup iptable rules to intercept outbound traffic from pods and run it across the
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// firewall chain corresponding to the pod so that egress network policies are enforced
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func (npc *NetworkPolicyController) interceptPodOutboundTraffic(pod *podInfo, podFwChainName string) {
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egressFilterChains := []string{kubeInputChainName, kubeForwardChainName, kubeOutputChainName}
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for _, chain := range egressFilterChains {
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// ensure there is rule in filter table and FORWARD chain to jump to pod specific firewall chain
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// this rule applies to the traffic getting forwarded/routed (traffic from the pod destinted
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// to pod on a different node)
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comment := "\"rule to jump traffic from POD name:" + pod.name + " namespace: " + pod.namespace +
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" to chain " + podFwChainName + "\""
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args := []string{"-I", chain, "1", "-m", "comment", "--comment", comment, "-s", pod.ip, "-j", podFwChainName, "\n"}
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npc.filterTableRules.WriteString(strings.Join(args, " "))
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}
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// ensure there is rule in filter table and forward chain to jump to pod specific firewall chain
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// this rule applies to the traffic getting switched (coming for same node pods)
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comment := "\"rule to jump traffic from POD name:" + pod.name + " namespace: " + pod.namespace +
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" to chain " + podFwChainName + "\""
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args := []string{"-I", kubeForwardChainName, "1", "-m", "physdev", "--physdev-is-bridged",
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"-m", "comment", "--comment", comment,
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"-s", pod.ip,
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"-j", podFwChainName, "\n"}
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npc.filterTableRules.WriteString(strings.Join(args, " "))
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}
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func (npc *NetworkPolicyController) getLocalPods(nodeIP string) (*map[string]podInfo, error) {
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localPods := make(map[string]podInfo)
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for _, obj := range npc.podLister.List() {
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pod := obj.(*api.Pod)
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// ignore the pods running on the different node and pods that are not actionable
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if strings.Compare(pod.Status.HostIP, nodeIP) != 0 || !isNetPolActionable(pod) {
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continue
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}
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localPods[pod.Status.PodIP] = podInfo{ip: pod.Status.PodIP,
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name: pod.ObjectMeta.Name,
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namespace: pod.ObjectMeta.Namespace,
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labels: pod.ObjectMeta.Labels}
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}
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return &localPods, nil
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}
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func podFirewallChainName(namespace, podName string, version string) string {
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hash := sha256.Sum256([]byte(namespace + podName + version))
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encoded := base32.StdEncoding.EncodeToString(hash[:])
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return kubePodFirewallChainPrefix + encoded[:16]
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}
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