/usr/share/gocode/src/github.com/docker/libnetwork/drivers/bridge/setup_ip_tables.go is in golang-github-docker-libnetwork-dev 0.8.0-dev.2+git20170202.599.45b4086-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import (
"fmt"
"net"
"github.com/Sirupsen/logrus"
"github.com/docker/libnetwork/iptables"
)
// DockerChain: DOCKER iptable chain name
const (
DockerChain = "DOCKER"
IsolationChain = "DOCKER-ISOLATION"
)
func setupIPChains(config *configuration) (*iptables.ChainInfo, *iptables.ChainInfo, *iptables.ChainInfo, error) {
// Sanity check.
if config.EnableIPTables == false {
return nil, nil, nil, fmt.Errorf("cannot create new chains, EnableIPTable is disabled")
}
hairpinMode := !config.EnableUserlandProxy
natChain, err := iptables.NewChain(DockerChain, iptables.Nat, hairpinMode)
if err != nil {
return nil, nil, nil, fmt.Errorf("failed to create NAT chain: %v", err)
}
defer func() {
if err != nil {
if err := iptables.RemoveExistingChain(DockerChain, iptables.Nat); err != nil {
logrus.Warnf("failed on removing iptables NAT chain on cleanup: %v", err)
}
}
}()
filterChain, err := iptables.NewChain(DockerChain, iptables.Filter, false)
if err != nil {
return nil, nil, nil, fmt.Errorf("failed to create FILTER chain: %v", err)
}
defer func() {
if err != nil {
if err := iptables.RemoveExistingChain(DockerChain, iptables.Filter); err != nil {
logrus.Warnf("failed on removing iptables FILTER chain on cleanup: %v", err)
}
}
}()
isolationChain, err := iptables.NewChain(IsolationChain, iptables.Filter, false)
if err != nil {
return nil, nil, nil, fmt.Errorf("failed to create FILTER isolation chain: %v", err)
}
if err := addReturnRule(IsolationChain); err != nil {
return nil, nil, nil, err
}
return natChain, filterChain, isolationChain, nil
}
func (n *bridgeNetwork) setupIPTables(config *networkConfiguration, i *bridgeInterface) error {
var err error
d := n.driver
d.Lock()
driverConfig := d.config
d.Unlock()
// Sanity check.
if driverConfig.EnableIPTables == false {
return fmt.Errorf("Cannot program chains, EnableIPTable is disabled")
}
// Pickup this configuration option from driver
hairpinMode := !driverConfig.EnableUserlandProxy
maskedAddrv4 := &net.IPNet{
IP: i.bridgeIPv4.IP.Mask(i.bridgeIPv4.Mask),
Mask: i.bridgeIPv4.Mask,
}
if config.Internal {
if err = setupInternalNetworkRules(config.BridgeName, maskedAddrv4, config.EnableICC, true); err != nil {
return fmt.Errorf("Failed to Setup IP tables: %s", err.Error())
}
n.registerIptCleanFunc(func() error {
return setupInternalNetworkRules(config.BridgeName, maskedAddrv4, config.EnableICC, false)
})
} else {
if err = setupIPTablesInternal(config.BridgeName, maskedAddrv4, config.EnableICC, config.EnableIPMasquerade, hairpinMode, true); err != nil {
return fmt.Errorf("Failed to Setup IP tables: %s", err.Error())
}
n.registerIptCleanFunc(func() error {
return setupIPTablesInternal(config.BridgeName, maskedAddrv4, config.EnableICC, config.EnableIPMasquerade, hairpinMode, false)
})
natChain, filterChain, _, err := n.getDriverChains()
if err != nil {
return fmt.Errorf("Failed to setup IP tables, cannot acquire chain info %s", err.Error())
}
err = iptables.ProgramChain(natChain, config.BridgeName, hairpinMode, true)
if err != nil {
return fmt.Errorf("Failed to program NAT chain: %s", err.Error())
}
err = iptables.ProgramChain(filterChain, config.BridgeName, hairpinMode, true)
if err != nil {
return fmt.Errorf("Failed to program FILTER chain: %s", err.Error())
}
n.registerIptCleanFunc(func() error {
return iptables.ProgramChain(filterChain, config.BridgeName, hairpinMode, false)
})
n.portMapper.SetIptablesChain(natChain, n.getNetworkBridgeName())
}
if err := ensureJumpRule("FORWARD", IsolationChain); err != nil {
return err
}
return nil
}
type iptRule struct {
table iptables.Table
chain string
preArgs []string
args []string
}
func setupIPTablesInternal(bridgeIface string, addr net.Addr, icc, ipmasq, hairpin, enable bool) error {
var (
address = addr.String()
natRule = iptRule{table: iptables.Nat, chain: "POSTROUTING", preArgs: []string{"-t", "nat"}, args: []string{"-s", address, "!", "-o", bridgeIface, "-j", "MASQUERADE"}}
hpNatRule = iptRule{table: iptables.Nat, chain: "POSTROUTING", preArgs: []string{"-t", "nat"}, args: []string{"-m", "addrtype", "--src-type", "LOCAL", "-o", bridgeIface, "-j", "MASQUERADE"}}
skipDNAT = iptRule{table: iptables.Nat, chain: DockerChain, preArgs: []string{"-t", "nat"}, args: []string{"-i", bridgeIface, "-j", "RETURN"}}
outRule = iptRule{table: iptables.Filter, chain: "FORWARD", args: []string{"-i", bridgeIface, "!", "-o", bridgeIface, "-j", "ACCEPT"}}
inRule = iptRule{table: iptables.Filter, chain: "FORWARD", args: []string{"-o", bridgeIface, "-m", "conntrack", "--ctstate", "RELATED,ESTABLISHED", "-j", "ACCEPT"}}
)
// Set NAT.
if ipmasq {
if err := programChainRule(natRule, "NAT", enable); err != nil {
return err
}
}
if ipmasq && !hairpin {
if err := programChainRule(skipDNAT, "SKIP DNAT", enable); err != nil {
return err
}
}
// In hairpin mode, masquerade traffic from localhost
if hairpin {
if err := programChainRule(hpNatRule, "MASQ LOCAL HOST", enable); err != nil {
return err
}
}
// Set Inter Container Communication.
if err := setIcc(bridgeIface, icc, enable); err != nil {
return err
}
// Set Accept on all non-intercontainer outgoing packets.
if err := programChainRule(outRule, "ACCEPT NON_ICC OUTGOING", enable); err != nil {
return err
}
// Set Accept on incoming packets for existing connections.
if err := programChainRule(inRule, "ACCEPT INCOMING", enable); err != nil {
return err
}
return nil
}
func programChainRule(rule iptRule, ruleDescr string, insert bool) error {
var (
prefix []string
operation string
condition bool
doesExist = iptables.Exists(rule.table, rule.chain, rule.args...)
)
if insert {
condition = !doesExist
prefix = []string{"-I", rule.chain}
operation = "enable"
} else {
condition = doesExist
prefix = []string{"-D", rule.chain}
operation = "disable"
}
if rule.preArgs != nil {
prefix = append(rule.preArgs, prefix...)
}
if condition {
if err := iptables.RawCombinedOutput(append(prefix, rule.args...)...); err != nil {
return fmt.Errorf("Unable to %s %s rule: %s", operation, ruleDescr, err.Error())
}
}
return nil
}
func setIcc(bridgeIface string, iccEnable, insert bool) error {
var (
table = iptables.Filter
chain = "FORWARD"
args = []string{"-i", bridgeIface, "-o", bridgeIface, "-j"}
acceptArgs = append(args, "ACCEPT")
dropArgs = append(args, "DROP")
)
if insert {
if !iccEnable {
iptables.Raw(append([]string{"-D", chain}, acceptArgs...)...)
if !iptables.Exists(table, chain, dropArgs...) {
if err := iptables.RawCombinedOutput(append([]string{"-A", chain}, dropArgs...)...); err != nil {
return fmt.Errorf("Unable to prevent intercontainer communication: %s", err.Error())
}
}
} else {
iptables.Raw(append([]string{"-D", chain}, dropArgs...)...)
if !iptables.Exists(table, chain, acceptArgs...) {
if err := iptables.RawCombinedOutput(append([]string{"-I", chain}, acceptArgs...)...); err != nil {
return fmt.Errorf("Unable to allow intercontainer communication: %s", err.Error())
}
}
}
} else {
// Remove any ICC rule.
if !iccEnable {
if iptables.Exists(table, chain, dropArgs...) {
iptables.Raw(append([]string{"-D", chain}, dropArgs...)...)
}
} else {
if iptables.Exists(table, chain, acceptArgs...) {
iptables.Raw(append([]string{"-D", chain}, acceptArgs...)...)
}
}
}
return nil
}
// Control Inter Network Communication. Install/remove only if it is not/is present.
func setINC(iface1, iface2 string, enable bool) error {
var (
table = iptables.Filter
chain = IsolationChain
args = [2][]string{{"-i", iface1, "-o", iface2, "-j", "DROP"}, {"-i", iface2, "-o", iface1, "-j", "DROP"}}
)
if enable {
for i := 0; i < 2; i++ {
if iptables.Exists(table, chain, args[i]...) {
continue
}
if err := iptables.RawCombinedOutput(append([]string{"-I", chain}, args[i]...)...); err != nil {
return fmt.Errorf("unable to add inter-network communication rule: %v", err)
}
}
} else {
for i := 0; i < 2; i++ {
if !iptables.Exists(table, chain, args[i]...) {
continue
}
if err := iptables.RawCombinedOutput(append([]string{"-D", chain}, args[i]...)...); err != nil {
return fmt.Errorf("unable to remove inter-network communication rule: %v", err)
}
}
}
return nil
}
func addReturnRule(chain string) error {
var (
table = iptables.Filter
args = []string{"-j", "RETURN"}
)
if iptables.Exists(table, chain, args...) {
return nil
}
err := iptables.RawCombinedOutput(append([]string{"-I", chain}, args...)...)
if err != nil {
return fmt.Errorf("unable to add return rule in %s chain: %s", chain, err.Error())
}
return nil
}
// Ensure the jump rule is on top
func ensureJumpRule(fromChain, toChain string) error {
var (
table = iptables.Filter
args = []string{"-j", toChain}
)
if iptables.Exists(table, fromChain, args...) {
err := iptables.RawCombinedOutput(append([]string{"-D", fromChain}, args...)...)
if err != nil {
return fmt.Errorf("unable to remove jump to %s rule in %s chain: %s", toChain, fromChain, err.Error())
}
}
err := iptables.RawCombinedOutput(append([]string{"-I", fromChain}, args...)...)
if err != nil {
return fmt.Errorf("unable to insert jump to %s rule in %s chain: %s", toChain, fromChain, err.Error())
}
return nil
}
func removeIPChains() {
for _, chainInfo := range []iptables.ChainInfo{
{Name: DockerChain, Table: iptables.Nat},
{Name: DockerChain, Table: iptables.Filter},
{Name: IsolationChain, Table: iptables.Filter},
} {
if err := chainInfo.Remove(); err != nil {
logrus.Warnf("Failed to remove existing iptables entries in table %s chain %s : %v", chainInfo.Table, chainInfo.Name, err)
}
}
}
func setupInternalNetworkRules(bridgeIface string, addr net.Addr, icc, insert bool) error {
var (
inDropRule = iptRule{table: iptables.Filter, chain: IsolationChain, args: []string{"-i", bridgeIface, "!", "-d", addr.String(), "-j", "DROP"}}
outDropRule = iptRule{table: iptables.Filter, chain: IsolationChain, args: []string{"-o", bridgeIface, "!", "-s", addr.String(), "-j", "DROP"}}
)
if err := programChainRule(inDropRule, "DROP INCOMING", insert); err != nil {
return err
}
if err := programChainRule(outDropRule, "DROP OUTGOING", insert); err != nil {
return err
}
// Set Inter Container Communication.
if err := setIcc(bridgeIface, icc, insert); err != nil {
return err
}
return nil
}
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