incusd/network/bridge: Fix deletion of tunnels and dummy devices

internal/server/device/nic_macvlan.go

@@ -219,7 +219,7 @@ func (d *nicMACVLAN) Start() (*deviceConfig.RunConfig, error) {
 
 	if d.inst.Type() == instancetype.VM {
 		// Enable all multicast processing which is required for IPv6 NDP functionality.
-		link.AllMutlicast = true
+		link.AllMulticast = true
 
 		// Bring the interface up on host side.
 		link.Up = true

internal/server/ip/link.go

@@ -17,15 +17,30 @@ import (
 // Link represents base arguments for link device.
 type Link struct {
 	Name          string
+	Kind          string
 	MTU           uint32
 	Parent        string
 	Address       net.HardwareAddr
 	TXQueueLength uint32
-	AllMutlicast  bool
+	AllMulticast  bool
 	Master        string
 	Up            bool
 }
 
+type jsonLink struct {
+	Name          string `json:"ifname"`
+	MTU           uint32 `json:"mtu"`
+	Parent        string `json:"link"`
+	Address       string `json:"address"`
+	TXQueueLength uint32 `json:"txqlen"`
+	AllMulticast  int    `json:"allmulti"`
+	Master        string `json:"master"`
+	Up            string `json:"operstate"`
+	Info          struct {
+		Kind string `json:"info_kind"`
+	} `json:"linkinfo"`
+}
+
 // args generate common arguments for the virtual link.
 func (l *Link) args() []string {
 	var result []string
@@ -50,7 +65,7 @@ func (l *Link) args() []string {
 		result = append(result, "txqueuelen", fmt.Sprintf("%d", l.TXQueueLength))
 	}
 
-	if l.AllMutlicast {
+	if l.AllMulticast {
 		result = append(result, "allmulticast", "on")
 	}
 
@@ -79,6 +94,47 @@ func (l *Link) add(linkType string, additionalArgs []string) error {
 	return nil
 }
 
+// LinkFromName returns a Link from a device name.
+func LinkFromName(name string) (*Link, error) {
+	out, err := subprocess.RunCommand("ip", "-d", "-j", "link", "show", name)
+	if err != nil {
+		return nil, err
+	}
+
+	var links []jsonLink
+	err = json.Unmarshal([]byte(out), &links)
+	if err != nil {
+		return nil, fmt.Errorf("failed to decode JSON link representation: %w", err)
+	}
+
+	jl := &links[0]
+	l := &Link{
+		Name:          jl.Name,
+		Kind:          jl.Info.Kind,
+		MTU:           jl.MTU,
+		Parent:        jl.Parent,
+		TXQueueLength: jl.TXQueueLength,
+		Master:        jl.Master,
+	}
+
+	if jl.Address != "" {
+		l.Address, err = net.ParseMAC(jl.Address)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if jl.AllMulticast == 1 {
+		l.AllMulticast = true
+	}
+
+	if jl.Up == "UP" {
+		l.Up = true
+	}
+
+	return l, err
+}
+
 // SetUp enables the link device.
 func (l *Link) SetUp() error {
 	_, err := subprocess.RunCommand("ip", "link", "set", "dev", l.Name, "up")

internal/server/network/driver_bridge.go

@@ -671,14 +671,20 @@ func (n *bridge) setup(oldConfig map[string]string) error {
 		return err
 	}
 
-	// Cleanup any existing tunnel device.
+	// Cleanup any existing tunnel and dummy devices.
 	for _, iface := range ifaces {
-		if strings.HasPrefix(iface.Name, fmt.Sprintf("%s-", n.name)) {
-			tunLink := &ip.Link{Name: iface.Name}
-			err = tunLink.Delete()
-			if err != nil {
-				return err
-			}
+		l, err := ip.LinkFromName(iface.Name)
+		if err != nil {
+			return err
+		}
+
+		if l.Master != n.name || l.Kind != "vxlan" && l.Kind != "gretap" && l.Kind != "dummy" {
+			continue
+		}
+
+		err = l.Delete()
+		if err != nil {
+			return err
 		}
 	}