127 lines
3.4 KiB
Go
127 lines
3.4 KiB
Go
// Copyright 2015 CNI authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package ip
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import (
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"fmt"
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"net"
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"github.com/coreos/go-iptables/iptables"
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)
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// SetupIPMasq installs iptables rules to masquerade traffic
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// coming from ip of ipn and going outside of ipn
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func SetupIPMasq(ipn *net.IPNet, chain string, comment string) error {
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isV6 := ipn.IP.To4() == nil
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var ipt *iptables.IPTables
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var err error
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var multicastNet string
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if isV6 {
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ipt, err = iptables.NewWithProtocol(iptables.ProtocolIPv6)
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multicastNet = "ff00::/8"
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} else {
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ipt, err = iptables.NewWithProtocol(iptables.ProtocolIPv4)
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multicastNet = "224.0.0.0/4"
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}
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if err != nil {
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return fmt.Errorf("failed to locate iptables: %v", err)
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}
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// Create chain if doesn't exist
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exists := false
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chains, err := ipt.ListChains("nat")
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if err != nil {
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return fmt.Errorf("failed to list chains: %v", err)
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}
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for _, ch := range chains {
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if ch == chain {
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exists = true
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break
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}
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}
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if !exists {
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if err = ipt.NewChain("nat", chain); err != nil {
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return err
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}
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}
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// Packets to this network should not be touched
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if err := ipt.AppendUnique("nat", chain, "-d", ipn.String(), "-j", "ACCEPT", "-m", "comment", "--comment", comment); err != nil {
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return err
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}
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// Don't masquerade multicast - pods should be able to talk to other pods
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// on the local network via multicast.
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if err := ipt.AppendUnique("nat", chain, "!", "-d", multicastNet, "-j", "MASQUERADE", "-m", "comment", "--comment", comment); err != nil {
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return err
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}
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// Packets from the specific IP of this network will hit the chain
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return ipt.AppendUnique("nat", "POSTROUTING", "-s", ipn.IP.String(), "-j", chain, "-m", "comment", "--comment", comment)
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}
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// TeardownIPMasq undoes the effects of SetupIPMasq
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func TeardownIPMasq(ipn *net.IPNet, chain string, comment string) error {
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isV6 := ipn.IP.To4() == nil
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var ipt *iptables.IPTables
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var err error
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if isV6 {
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ipt, err = iptables.NewWithProtocol(iptables.ProtocolIPv6)
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} else {
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ipt, err = iptables.NewWithProtocol(iptables.ProtocolIPv4)
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}
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if err != nil {
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return fmt.Errorf("failed to locate iptables: %v", err)
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}
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err = ipt.Delete("nat", "POSTROUTING", "-s", ipn.IP.String(), "-j", chain, "-m", "comment", "--comment", comment)
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if err != nil && !isNotExist(err) {
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return err
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}
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// for downward compatibility
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err = ipt.Delete("nat", "POSTROUTING", "-s", ipn.String(), "-j", chain, "-m", "comment", "--comment", comment)
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if err != nil && !isNotExist(err) {
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return err
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}
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err = ipt.ClearChain("nat", chain)
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if err != nil && !isNotExist(err) {
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return err
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}
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err = ipt.DeleteChain("nat", chain)
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if err != nil && !isNotExist(err) {
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return err
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}
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return nil
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}
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// isNotExist returnst true if the error is from iptables indicating
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// that the target does not exist.
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func isNotExist(err error) bool {
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e, ok := err.(*iptables.Error)
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if !ok {
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return false
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}
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return e.IsNotExist()
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}
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