libnetwork/drivers/bridge/setup_ip_tables_linux.go
package bridge
import (
"context"
"errors"
"fmt"
"net"
"strings"
"github.com/containerd/log"
"github.com/docker/docker/errdefs"
"github.com/docker/docker/libnetwork/iptables"
"github.com/docker/docker/libnetwork/types"
"github.com/vishvananda/netlink"
)
// DockerChain: DOCKER iptable chain name
const (
DockerChain = "DOCKER"
// Isolation between bridge networks is achieved in two stages by means
// of the following two chains in the filter table. The first chain matches
// on the source interface being a bridge network's bridge and the
// destination being a different interface. A positive match leads to the
// second isolation chain. No match returns to the parent chain. The second
// isolation chain matches on destination interface being a bridge network's
// bridge. A positive match identifies a packet originated from one bridge
// network's bridge destined to another bridge network's bridge and will
// result in the packet being dropped. No match returns to the parent chain.
IsolationChain1 = "DOCKER-ISOLATION-STAGE-1"
IsolationChain2 = "DOCKER-ISOLATION-STAGE-2"
)
func setupIPChains(config configuration, version iptables.IPVersion) (natChain *iptables.ChainInfo, filterChain *iptables.ChainInfo, isolationChain1 *iptables.ChainInfo, isolationChain2 *iptables.ChainInfo, retErr error) {
// Sanity check.
if version == iptables.IPv4 && !config.EnableIPTables {
return nil, nil, nil, nil, errors.New("cannot create new chains, iptables is disabled")
}
if version == iptables.IPv6 && !config.EnableIP6Tables {
return nil, nil, nil, nil, errors.New("cannot create new chains, ip6tables is disabled")
}
iptable := iptables.GetIptable(version)
natChain, err := iptable.NewChain(DockerChain, iptables.Nat)
if err != nil {
return nil, nil, nil, nil, fmt.Errorf("failed to create NAT chain %s: %v", DockerChain, err)
}
defer func() {
if retErr != nil {
if err := iptable.RemoveExistingChain(DockerChain, iptables.Nat); err != nil {
log.G(context.TODO()).Warnf("failed on removing iptables NAT chain %s on cleanup: %v", DockerChain, err)
}
}
}()
filterChain, err = iptable.NewChain(DockerChain, iptables.Filter)
if err != nil {
return nil, nil, nil, nil, fmt.Errorf("failed to create FILTER chain %s: %v", DockerChain, err)
}
defer func() {
if err != nil {
if err := iptable.RemoveExistingChain(DockerChain, iptables.Filter); err != nil {
log.G(context.TODO()).Warnf("failed on removing iptables FILTER chain %s on cleanup: %v", DockerChain, err)
}
}
}()
isolationChain1, err = iptable.NewChain(IsolationChain1, iptables.Filter)
if err != nil {
return nil, nil, nil, nil, fmt.Errorf("failed to create FILTER isolation chain: %v", err)
}
defer func() {
if retErr != nil {
if err := iptable.RemoveExistingChain(IsolationChain1, iptables.Filter); err != nil {
log.G(context.TODO()).Warnf("failed on removing iptables FILTER chain %s on cleanup: %v", IsolationChain1, err)
}
}
}()
isolationChain2, err = iptable.NewChain(IsolationChain2, iptables.Filter)
if err != nil {
return nil, nil, nil, nil, fmt.Errorf("failed to create FILTER isolation chain: %v", err)
}
defer func() {
if retErr != nil {
if err := iptable.RemoveExistingChain(IsolationChain2, iptables.Filter); err != nil {
log.G(context.TODO()).Warnf("failed on removing iptables FILTER chain %s on cleanup: %v", IsolationChain2, err)
}
}
}()
if err := iptable.AddReturnRule(IsolationChain1); err != nil {
return nil, nil, nil, nil, err
}
if err := iptable.AddReturnRule(IsolationChain2); err != nil {
return nil, nil, nil, nil, err
}
return natChain, filterChain, isolationChain1, isolationChain2, nil
}
func (n *bridgeNetwork) setupIP4Tables(config *networkConfiguration, i *bridgeInterface) error {
d := n.driver
d.Lock()
driverConfig := d.config
d.Unlock()
// Sanity check.
if !driverConfig.EnableIPTables {
return errors.New("Cannot program chains, EnableIPTable is disabled")
}
maskedAddrv4 := &net.IPNet{
IP: i.bridgeIPv4.IP.Mask(i.bridgeIPv4.Mask),
Mask: i.bridgeIPv4.Mask,
}
return n.setupIPTables(iptables.IPv4, maskedAddrv4, config, i)
}
func (n *bridgeNetwork) setupIP6Tables(config *networkConfiguration, i *bridgeInterface) error {
d := n.driver
d.Lock()
driverConfig := d.config
d.Unlock()
// Sanity check.
if !driverConfig.EnableIP6Tables {
return errors.New("Cannot program chains, EnableIP6Tables is disabled")
}
maskedAddrv6 := &net.IPNet{
IP: i.bridgeIPv6.IP.Mask(i.bridgeIPv6.Mask),
Mask: i.bridgeIPv6.Mask,
}
return n.setupIPTables(iptables.IPv6, maskedAddrv6, config, i)
}
func (n *bridgeNetwork) setupIPTables(ipVersion iptables.IPVersion, maskedAddr *net.IPNet, config *networkConfiguration, i *bridgeInterface) error {
var err error
d := n.driver
d.Lock()
driverConfig := d.config
d.Unlock()
// Pickup this configuration option from driver
hairpinMode := !driverConfig.EnableUserlandProxy
iptable := iptables.GetIptable(ipVersion)
if config.Internal {
if err = setupInternalNetworkRules(config.BridgeName, maskedAddr, config.EnableICC, true); err != nil {
return fmt.Errorf("Failed to Setup IP tables: %s", err.Error())
}
n.registerIptCleanFunc(func() error {
return setupInternalNetworkRules(config.BridgeName, maskedAddr, config.EnableICC, false)
})
} else {
if err = setupIPTablesInternal(ipVersion, config, maskedAddr, hairpinMode, true); err != nil {
return fmt.Errorf("Failed to Setup IP tables: %s", err.Error())
}
n.registerIptCleanFunc(func() error {
return setupIPTablesInternal(ipVersion, config, maskedAddr, hairpinMode, false)
})
natChain, filterChain, _, _, err := n.getDriverChains(ipVersion)
if err != nil {
return fmt.Errorf("Failed to setup IP tables, cannot acquire chain info %s", err.Error())
}
err = iptable.ProgramChain(natChain, config.BridgeName, hairpinMode, true)
if err != nil {
return fmt.Errorf("Failed to program NAT chain: %s", err.Error())
}
err = iptable.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 iptable.ProgramChain(filterChain, config.BridgeName, hairpinMode, false)
})
}
d.Lock()
err = iptable.EnsureJumpRule("FORWARD", IsolationChain1)
d.Unlock()
return err
}
type iptRule struct {
ipv iptables.IPVersion
table iptables.Table
chain string
args []string
}
// Exists returns true if the rule exists in the kernel.
func (r iptRule) Exists() bool {
return iptables.GetIptable(r.ipv).Exists(r.table, r.chain, r.args...)
}
func (r iptRule) cmdArgs(op iptables.Action) []string {
return append([]string{"-t", string(r.table), string(op), r.chain}, r.args...)
}
func (r iptRule) exec(op iptables.Action) error {
return iptables.GetIptable(r.ipv).RawCombinedOutput(r.cmdArgs(op)...)
}
// Append appends the rule to the end of the chain. If the rule already exists anywhere in the
// chain, this is a no-op.
func (r iptRule) Append() error {
if r.Exists() {
return nil
}
return r.exec(iptables.Append)
}
// Insert inserts the rule at the head of the chain. If the rule already exists anywhere in the
// chain, this is a no-op.
func (r iptRule) Insert() error {
if r.Exists() {
return nil
}
return r.exec(iptables.Insert)
}
// Delete deletes the rule from the kernel. If the rule does not exist, this is a no-op.
func (r iptRule) Delete() error {
if !r.Exists() {
return nil
}
return r.exec(iptables.Delete)
}
func (r iptRule) String() string {
cmd := append([]string{"iptables"}, r.cmdArgs("-A")...)
if r.ipv == iptables.IPv6 {
cmd[0] = "ip6tables"
}
return strings.Join(cmd, " ")
}
func setupIPTablesInternal(ipVer iptables.IPVersion, config *networkConfiguration, addr *net.IPNet, hairpin, enable bool) error {
var (
address = addr.String()
skipDNAT = iptRule{ipv: ipVer, table: iptables.Nat, chain: DockerChain, args: []string{"-i", config.BridgeName, "-j", "RETURN"}}
outRule = iptRule{ipv: ipVer, table: iptables.Filter, chain: "FORWARD", args: []string{"-i", config.BridgeName, "!", "-o", config.BridgeName, "-j", "ACCEPT"}}
natArgs []string
hpNatArgs []string
)
hostIP := config.HostIPv4
nat := !config.GwModeIPv4.natDisabled()
if ipVer == iptables.IPv6 {
hostIP = config.HostIPv6
nat = !config.GwModeIPv6.natDisabled()
}
// If hostIP is set, the user wants IPv4/IPv6 SNAT with the given address.
if hostIP != nil {
hostAddr := hostIP.String()
natArgs = []string{"-s", address, "!", "-o", config.BridgeName, "-j", "SNAT", "--to-source", hostAddr}
hpNatArgs = []string{"-m", "addrtype", "--src-type", "LOCAL", "-o", config.BridgeName, "-j", "SNAT", "--to-source", hostAddr}
// Else use MASQUERADE which picks the src-ip based on NH from the route table
} else {
natArgs = []string{"-s", address, "!", "-o", config.BridgeName, "-j", "MASQUERADE"}
hpNatArgs = []string{"-m", "addrtype", "--src-type", "LOCAL", "-o", config.BridgeName, "-j", "MASQUERADE"}
}
natRule := iptRule{ipv: ipVer, table: iptables.Nat, chain: "POSTROUTING", args: natArgs}
hpNatRule := iptRule{ipv: ipVer, table: iptables.Nat, chain: "POSTROUTING", args: hpNatArgs}
// Set NAT.
if nat && config.EnableIPMasquerade {
if err := programChainRule(natRule, "NAT", enable); err != nil {
return err
}
if !hairpin {
if err := programChainRule(skipDNAT, "SKIP DNAT", enable); err != nil {
return err
}
}
}
// In hairpin mode, masquerade traffic from localhost. If hairpin is disabled or if we're tearing down
// that bridge, make sure the iptables rule isn't lying around.
if err := programChainRule(hpNatRule, "MASQ LOCAL HOST", enable && hairpin); err != nil {
return err
}
// Set Inter Container Communication.
if err := setIcc(ipVer, config.BridgeName, config.EnableICC, enable); err != nil {
return err
}
// Set Accept on all non-intercontainer outgoing packets.
return programChainRule(outRule, "ACCEPT NON_ICC OUTGOING", enable)
}
func programChainRule(rule iptRule, ruleDescr string, insert bool) error {
operation := "disable"
fn := rule.Delete
if insert {
operation = "enable"
fn = rule.Insert
}
if err := fn(); err != nil {
return fmt.Errorf("Unable to %s %s rule: %s", operation, ruleDescr, err.Error())
}
return nil
}
func appendOrDelChainRule(rule iptRule, ruleDescr string, append bool) error {
operation := "disable"
fn := rule.Delete
if append {
operation = "enable"
fn = rule.Append
}
if err := fn(); err != nil {
return fmt.Errorf("Unable to %s %s rule: %s", operation, ruleDescr, err.Error())
}
return nil
}
func setIcc(version iptables.IPVersion, bridgeIface string, iccEnable, insert bool) error {
args := []string{"-i", bridgeIface, "-o", bridgeIface, "-j"}
acceptRule := iptRule{ipv: version, table: iptables.Filter, chain: "FORWARD", args: append(args, "ACCEPT")}
dropRule := iptRule{ipv: version, table: iptables.Filter, chain: "FORWARD", args: append(args, "DROP")}
if insert {
if !iccEnable {
acceptRule.Delete()
if err := dropRule.Append(); err != nil {
return fmt.Errorf("Unable to prevent intercontainer communication: %s", err.Error())
}
} else {
dropRule.Delete()
if err := acceptRule.Insert(); err != nil {
return fmt.Errorf("Unable to allow intercontainer communication: %s", err.Error())
}
}
} else {
// Remove any ICC rule.
if !iccEnable {
dropRule.Delete()
} else {
acceptRule.Delete()
}
}
return nil
}
// Control Inter Network Communication. Install[Remove] only if it is [not] present.
func setINC(version iptables.IPVersion, iface string, enable bool) error {
iptable := iptables.GetIptable(version)
var (
action = iptables.Insert
actionMsg = "add"
chains = []string{IsolationChain1, IsolationChain2}
rules = [][]string{
{"-i", iface, "!", "-o", iface, "-j", IsolationChain2},
{"-o", iface, "-j", "DROP"},
}
)
if !enable {
action = iptables.Delete
actionMsg = "remove"
}
for i, chain := range chains {
if err := iptable.ProgramRule(iptables.Filter, chain, action, rules[i]); err != nil {
msg := fmt.Sprintf("unable to %s inter-network communication rule: %v", actionMsg, err)
if enable {
if i == 1 {
// Rollback the rule installed on first chain
if err2 := iptable.ProgramRule(iptables.Filter, chains[0], iptables.Delete, rules[0]); err2 != nil {
log.G(context.TODO()).Warnf("Failed to rollback iptables rule after failure (%v): %v", err, err2)
}
}
return fmt.Errorf(msg)
}
log.G(context.TODO()).Warn(msg)
}
}
return nil
}
// Obsolete chain from previous docker versions
const oldIsolationChain = "DOCKER-ISOLATION"
func removeIPChains(version iptables.IPVersion) {
ipt := iptables.GetIptable(version)
// Remove obsolete rules from default chains
ipt.ProgramRule(iptables.Filter, "FORWARD", iptables.Delete, []string{"-j", oldIsolationChain})
// Remove chains
for _, chainInfo := range []iptables.ChainInfo{
{Name: DockerChain, Table: iptables.Nat, IPVersion: version},
{Name: DockerChain, Table: iptables.Filter, IPVersion: version},
{Name: IsolationChain1, Table: iptables.Filter, IPVersion: version},
{Name: IsolationChain2, Table: iptables.Filter, IPVersion: version},
{Name: oldIsolationChain, Table: iptables.Filter, IPVersion: version},
} {
if err := chainInfo.Remove(); err != nil {
log.G(context.TODO()).Warnf("Failed to remove existing iptables entries in table %s chain %s : %v", chainInfo.Table, chainInfo.Name, err)
}
}
}
func setupInternalNetworkRules(bridgeIface string, addr *net.IPNet, icc, insert bool) error {
var version iptables.IPVersion
var inDropRule, outDropRule iptRule
// Either add or remove the interface from the firewalld zone, if firewalld is running.
if insert {
if err := iptables.AddInterfaceFirewalld(bridgeIface); err != nil {
return err
}
} else {
if err := iptables.DelInterfaceFirewalld(bridgeIface); err != nil && !errdefs.IsNotFound(err) {
return err
}
}
if addr.IP.To4() != nil {
version = iptables.IPv4
inDropRule = iptRule{
ipv: version,
table: iptables.Filter,
chain: IsolationChain1,
args: []string{"-i", bridgeIface, "!", "-d", addr.String(), "-j", "DROP"},
}
outDropRule = iptRule{
ipv: version,
table: iptables.Filter,
chain: IsolationChain1,
args: []string{"-o", bridgeIface, "!", "-s", addr.String(), "-j", "DROP"},
}
} else {
version = iptables.IPv6
inDropRule = iptRule{
ipv: version,
table: iptables.Filter,
chain: IsolationChain1,
args: []string{"-i", bridgeIface, "!", "-o", bridgeIface, "!", "-d", addr.String(), "-j", "DROP"},
}
outDropRule = iptRule{
ipv: version,
table: iptables.Filter,
chain: IsolationChain1,
args: []string{"!", "-i", bridgeIface, "-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.
return setIcc(version, bridgeIface, icc, insert)
}
// clearConntrackEntries flushes conntrack entries matching endpoint IP address
// or matching one of the exposed UDP port.
// In the first case, this could happen if packets were received by the host
// between userland proxy startup and iptables setup.
// In the latter case, this could happen if packets were received whereas there
// were nowhere to route them, as netfilter creates entries in such case.
// This is required because iptables NAT rules are evaluated by netfilter only
// when creating a new conntrack entry. When Docker latter adds NAT rules,
// netfilter ignore them for any packet matching a pre-existing conntrack entry.
// As such, we need to flush all those conntrack entries to make sure NAT rules
// are correctly applied to all packets.
// See: #8795, #44688 & #44742.
func clearConntrackEntries(nlh *netlink.Handle, ep *bridgeEndpoint) {
var ipv4List []net.IP
var ipv6List []net.IP
var udpPorts []uint16
if ep.addr != nil {
ipv4List = append(ipv4List, ep.addr.IP)
}
if ep.addrv6 != nil {
ipv6List = append(ipv6List, ep.addrv6.IP)
}
for _, pb := range ep.portMapping {
if pb.Proto == types.UDP {
udpPorts = append(udpPorts, pb.HostPort)
}
}
iptables.DeleteConntrackEntries(nlh, ipv4List, ipv6List)
iptables.DeleteConntrackEntriesByPort(nlh, types.UDP, udpPorts)
}