libnetwork: arrangeUserFilterRule: don't return early

commit ffd75c2e0c updated this function to
set up the DOCKER-USER chain for both iptables and ip6tables, however the
function would return early if a failure happened (instead of continuing
with the next iptables version).

This patch extracts setting up the chain to a separate function, and updates
arrangeUserFilterRule to log the failure as a warning, but continue with
the next iptables version.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

libnetwork/firewall_linux.go

@@ -2,6 +2,7 @@ package libnetwork
 
 import (
 	"context"
+	"fmt"
 
 	"github.com/containerd/containerd/log"
 	"github.com/docker/docker/libnetwork/iptables"
@@ -18,6 +19,18 @@ func setupArrangeUserFilterRule(c *Controller) {
 
 // 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
@@ -26,23 +39,16 @@ func setupArrangeUserFilterRule(c *Controller) {
 // 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 arrangeUserFilterRule() {
+func setupUserChain(ipVersion iptables.IPVersion) error {
-	if ctrl == nil {
-		return
-	}
-
-	for _, ipVersion := range ctrl.enabledIptablesVersions() {
 	ipt := iptables.GetIptable(ipVersion)
 	if _, err := ipt.NewChain(userChain, iptables.Filter, false); err != nil {
-			log.G(context.TODO()).WithError(err).Warnf("Failed to create %s %v chain", userChain, ipVersion)
+		return fmt.Errorf("failed to create %s %v chain: %v", userChain, ipVersion, err)
-			return
 	}
 	if err := ipt.AddReturnRule(userChain); err != nil {
-			log.G(context.TODO()).WithError(err).Warnf("Failed to add the RETURN rule for %s %v", userChain, ipVersion)
+		return fmt.Errorf("failed to add the RETURN rule for %s %v: %w", userChain, ipVersion, err)
-			return
 	}
 	if err := ipt.EnsureJumpRule("FORWARD", userChain); err != nil {
-			log.G(context.TODO()).WithError(err).Warnf("Failed to ensure the jump rule for %s %v", userChain, ipVersion)
+		return fmt.Errorf("failed to ensure the jump rule for %s %v: %w", userChain, ipVersion, err)
-		}
 	}
+	return nil
 }

libnetwork/firewall_others.go

@@ -4,3 +4,4 @@ package libnetwork
 
 func setupArrangeUserFilterRule(c *Controller) {}
 func arrangeUserFilterRule()                   {}
+func setupUserChain(ipVersion any) error       { return nil }