feat(wireguard): WIREGUARD_GSO option to disable TUN vnet hdr batching (#3424)

internal/configuration/settings/wireguard.go

@@ -46,6 +46,13 @@ type Wireguard struct {
 	// It defaults to "auto" and cannot be the empty string
 	// in the internal state.
 	Implementation string `json:"implementation"`
+	// GSO enables wireguard-go's GRO/GSO batched TUN I/O by creating
+	// the WireGuard TUN device with IFF_VNET_HDR. It should be disabled
+	// on kernels (e.g. certain NAS devices) that claim IFF_VNET_HDR
+	// support but return EINVAL when wireguard-go writes GRO-coalesced
+	// packets with virtio_net_hdr structs under load.
+	// It defaults to true and cannot be nil in the internal state.
+	GSO *bool `json:"gso"`
 }
 
 var regexpInterfaceName = regexp.MustCompile(`^[a-zA-Z0-9_]+$`)
@@ -136,6 +143,7 @@ func (w *Wireguard) copy() (copied Wireguard) {
 		Interface:                   w.Interface,
 		MTU:                         w.MTU,
 		Implementation:              w.Implementation,
+		GSO:                         gosettings.CopyPointer(w.GSO),
 	}
 }
 
@@ -149,6 +157,7 @@ func (w *Wireguard) overrideWith(other Wireguard) {
 	w.Interface = gosettings.OverrideWithComparable(w.Interface, other.Interface)
 	w.MTU = gosettings.OverrideWithComparable(w.MTU, other.MTU)
 	w.Implementation = gosettings.OverrideWithComparable(w.Implementation, other.Implementation)
+	w.GSO = gosettings.OverrideWithPointer(w.GSO, other.GSO)
 }
 
 func (w *Wireguard) setDefaults(vpnProvider string) {
@@ -173,6 +182,7 @@ func (w *Wireguard) setDefaults(vpnProvider string) {
 	w.Interface = gosettings.DefaultComparable(w.Interface, "wg0")
 	w.MTU = gosettings.DefaultPointer(w.MTU, 0)
 	w.Implementation = gosettings.DefaultComparable(w.Implementation, "auto")
+	w.GSO = gosettings.DefaultPointer(w.GSO, true)
 }
 
 func (w Wireguard) String() string {
@@ -217,6 +227,10 @@ func (w Wireguard) toLinesNode() (node *gotree.Node) {
 		node.Appendf("Implementation: %s", w.Implementation)
 	}
 
+	if !*w.GSO {
+		node.Append("GSO disabled")
+	}
+
 	return node
 }
 
@@ -265,5 +279,11 @@ func (w *Wireguard) read(r *reader.Reader, amneziaWG bool) (err error) {
 	if err != nil {
 		return err
 	}
+
+	w.GSO, err = r.BoolPtr("WIREGUARD_GSO")
+	if err != nil {
+		return err
+	}
+
 	return nil
 }