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package libnetwork
import (
"context"
"fmt"
"github.com/containerd/log"
"github.com/docker/docker/libnetwork/iptables"
)
const userChain = "DOCKER-USER"
var ctrl *Controller
func setupArrangeUserFilterRule(c *Controller) {
ctrl = c
iptables.OnReloaded(arrangeUserFilterRule)
}
// arrangeUserFilterRule sets up the DOCKER-USER chain for each iptables version
// (IPv4, IPv6) that's enabled in the controller's configuration.
func arrangeUserFilterRule() {
if ctrl == nil {
return
}
for _, ipVersion := range ctrl.enabledIptablesVersions() {
if err := setupUserChain(ipVersion); err != nil {
log.G(context.TODO()).WithError(err).Warn("arrangeUserFilterRule")
}
}
}
// setupUserChain sets up the DOCKER-USER chain for the given [iptables.IPVersion].
//
// This chain allows users to configure firewall policies in a way that
// persist daemon operations/restarts. The daemon does not delete or modify
// any pre-existing rules from the DOCKER-USER filter chain.
//
// Once the DOCKER-USER chain is created, the daemon does not remove it when
// IPTableForwarding is disabled, because it contains rules configured by user
// that are beyond the daemon's control.
func setupUserChain(ipVersion iptables.IPVersion) error {
ipt := iptables.GetIptable(ipVersion)
if _, err := ipt.NewChain(userChain, iptables.Filter, false); err != nil {
return fmt.Errorf("failed to create %s %v chain: %v", userChain, ipVersion, err)
}
if err := ipt.AddReturnRule(userChain); err != nil {
return fmt.Errorf("failed to add the RETURN rule for %s %v: %w", userChain, ipVersion, err)
}
if err := ipt.EnsureJumpRule("FORWARD", userChain); err != nil {
return fmt.Errorf("failed to ensure the jump rule for %s %v: %w", userChain, ipVersion, err)
}
return nil
}
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