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node_iptables.go
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node_iptables.go
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package plugin
import (
"fmt"
"sync"
"time"
"github.com/golang/glog"
utilwait "k8s.io/apimachinery/pkg/util/wait"
utildbus "k8s.io/kubernetes/pkg/util/dbus"
kexec "k8s.io/kubernetes/pkg/util/exec"
"k8s.io/kubernetes/pkg/util/iptables"
)
type NodeIPTables struct {
ipt iptables.Interface
clusterNetworkCIDR string
syncPeriod time.Duration
masqueradeServices bool
mu sync.Mutex // Protects concurrent access to syncIPTableRules()
}
func newNodeIPTables(clusterNetworkCIDR string, syncPeriod time.Duration, masqueradeServices bool) *NodeIPTables {
return &NodeIPTables{
ipt: iptables.New(kexec.New(), utildbus.New(), iptables.ProtocolIpv4),
clusterNetworkCIDR: clusterNetworkCIDR,
syncPeriod: syncPeriod,
masqueradeServices: masqueradeServices,
}
}
func (n *NodeIPTables) Setup() error {
if err := n.syncIPTableRules(); err != nil {
return err
}
// If firewalld is running, reload will call this method
n.ipt.AddReloadFunc(func() {
if err := n.syncIPTableRules(); err != nil {
glog.Errorf("Reloading openshift iptables failed: %v", err)
}
})
go utilwait.Forever(n.syncLoop, 0)
return nil
}
// syncLoop periodically calls syncIPTableRules().
// This is expected to run as a go routine or as the main loop. It does not return.
func (n *NodeIPTables) syncLoop() {
t := time.NewTicker(n.syncPeriod)
defer t.Stop()
for {
<-t.C
glog.V(6).Infof("Periodic openshift iptables sync")
err := n.syncIPTableRules()
if err != nil {
glog.Errorf("Syncing openshift iptables failed: %v", err)
}
}
}
type Chain struct {
table string
name string
srcChain string
srcRule []string
rules [][]string
}
// Adds all the rules in chain, returning true if they were all already present
func (n *NodeIPTables) addChainRules(chain Chain) (bool, error) {
allExisted := true
for _, rule := range chain.rules {
existed, err := n.ipt.EnsureRule(iptables.Append, iptables.Table(chain.table), iptables.Chain(chain.name), rule...)
if err != nil {
return false, fmt.Errorf("failed to ensure rule %v exists: %v", rule, err)
}
if !existed {
allExisted = false
}
}
return allExisted, nil
}
// syncIPTableRules syncs the cluster network cidr iptables rules.
// Called from SyncLoop() or firewalld reload()
func (n *NodeIPTables) syncIPTableRules() error {
n.mu.Lock()
defer n.mu.Unlock()
start := time.Now()
defer func() {
glog.V(4).Infof("syncIPTableRules took %v", time.Since(start))
}()
glog.V(3).Infof("Syncing openshift iptables rules")
for _, chain := range n.getNodeIPTablesChains() {
// Create chain if it does not already exist
chainExisted, err := n.ipt.EnsureChain(iptables.Table(chain.table), iptables.Chain(chain.name))
if err != nil {
return fmt.Errorf("failed to ensure chain %s exists: %v", chain.name, err)
}
// Create the rule pointing to it from its parent chain. Note that since we
// use iptables.Prepend each time, chains with the same table and srcChain
// (ie, OPENSHIFT-FIREWALL-FORWARD and OPENSHIFT-ADMIN-OUTPUT-RULES) will
// run in *reverse* order of how they are listed in getNodeIPTablesChains().
_, err = n.ipt.EnsureRule(iptables.Prepend, iptables.Table(chain.table), iptables.Chain(chain.srcChain), append(chain.srcRule, "-j", chain.name)...)
if err != nil {
return fmt.Errorf("failed to ensure rule from %s to %s exists: %v", chain.srcChain, chain.name, err)
}
// Add/sync the rules
rulesExisted, err := n.addChainRules(chain)
if err != nil {
return err
}
if chainExisted && !rulesExisted {
// Chain existed but not with the expected rules; this probably means
// it contained rules referring to a *different* subnet; flush them
// and try again.
if err = n.ipt.FlushChain(iptables.Table(chain.table), iptables.Chain(chain.name)); err != nil {
return fmt.Errorf("failed to flush chain %s: %v", chain.name, err)
}
if _, err = n.addChainRules(chain); err != nil {
return err
}
}
}
return nil
}
const VXLAN_PORT = "4789"
func (n *NodeIPTables) getNodeIPTablesChains() []Chain {
var masqRule []string
if n.masqueradeServices {
masqRule = []string{"-s", n.clusterNetworkCIDR, "-m", "comment", "--comment", "masquerade pod-to-service and pod-to-external traffic", "-j", "MASQUERADE"}
} else {
masqRule = []string{"-s", n.clusterNetworkCIDR, "!", "-d", n.clusterNetworkCIDR, "-m", "comment", "--comment", "masquerade pod-to-external traffic", "-j", "MASQUERADE"}
}
return []Chain{
{
table: "nat",
name: "OPENSHIFT-MASQUERADE",
srcChain: "POSTROUTING",
srcRule: []string{"-m", "comment", "--comment", "rules for masquerading OpenShift traffic"},
rules: [][]string{
masqRule,
},
},
{
table: "filter",
name: "OPENSHIFT-FIREWALL-ALLOW",
srcChain: "INPUT",
srcRule: []string{"-m", "comment", "--comment", "firewall overrides"},
rules: [][]string{
{"-p", "udp", "--dport", VXLAN_PORT, "-m", "comment", "--comment", "VXLAN incoming", "-j", "ACCEPT"},
{"-i", TUN, "-m", "comment", "--comment", "from SDN to localhost", "-j", "ACCEPT"},
{"-i", "docker0", "-m", "comment", "--comment", "from docker to localhost", "-j", "ACCEPT"},
},
},
{
table: "filter",
name: "OPENSHIFT-FIREWALL-FORWARD",
srcChain: "FORWARD",
srcRule: []string{"-m", "comment", "--comment", "firewall overrides"},
rules: [][]string{
{"-s", n.clusterNetworkCIDR, "-m", "comment", "--comment", "attempted resend after connection close", "-m", "conntrack", "--ctstate", "INVALID", "-j", "DROP"},
{"-d", n.clusterNetworkCIDR, "-m", "comment", "--comment", "forward traffic from SDN", "-j", "ACCEPT"},
{"-s", n.clusterNetworkCIDR, "-m", "comment", "--comment", "forward traffic to SDN", "-j", "ACCEPT"},
},
},
{
table: "filter",
name: "OPENSHIFT-ADMIN-OUTPUT-RULES",
srcChain: "FORWARD",
srcRule: []string{"-i", TUN, "!", "-o", TUN, "-m", "comment", "--comment", "administrator overrides"},
rules: nil,
},
}
}