Remove unexpected AltName after rename interface (antrea-io#6321)

Fix antrea-io#6301

Signed-off-by: gran <[email protected]>
Co-authored-by: Lan <[email protected]>

pkg/agent/util/net_linux.go

@@ -291,6 +291,15 @@ func RenameInterface(from, to string) error {
 	if pollErr != nil {
 		return fmt.Errorf("failed to rename host interface name %s to %s", from, to)
 	}
+	// Fix for the issue https://github.com/antrea-io/antrea/issues/6301.
+	// In some new Linux versions which support AltName, if the only valid altname of the interface is the same as the
+	// interface name, it would be left empty when the name is occupied by the interface name; after we rename the
+	// interface name to another value, the altname of the interface would be set to the original interface name by the
+	// system.
+	// This altname must be removed as we need to reserve the name for an OVS internal port.
+	if err := removeInterfaceAltName(to, from); err != nil {
+		return fmt.Errorf("failed to remove AltName %s on interface %s: %w", from, to, err)
+	}
 	return nil
 }
 
@@ -392,6 +401,20 @@ func interfaceExists(name string) (bool, error) {
 	return false, nil
 }
 
+// removeInterfaceAltName removes altName on interface with provided name. altName not found will return nil.
+func removeInterfaceAltName(name string, altName string) error {
+	link, err := netlinkUtil.LinkByName(name)
+	if err != nil {
+		return err
+	}
+	for _, existAltName := range link.Attrs().AltNames {
+		if existAltName == altName {
+			return netlinkUtil.LinkDelAltName(link, altName)
+		}
+	}
+	return nil
+}
+
 // PrepareHostInterfaceConnection prepares host interface connection to the OVS bridge client by:
 // 1. Renaming the host interface (a bridged suffix will be added to it).
 // 2. Creating an internal port (original name of the host interface will be used here).

pkg/agent/util/net_linux_test.go

@@ -36,6 +36,7 @@ type mockLink struct {
 	name         string
 	masterIndex  int
 	hardwareAddr net.HardwareAddr
+	altNames     []string
 }
 
 func (l mockLink) Attrs() *netlink.LinkAttrs {
@@ -44,6 +45,7 @@ func (l mockLink) Attrs() *netlink.LinkAttrs {
 		Name:         l.name,
 		MasterIndex:  l.masterIndex,
 		HardwareAddr: l.hardwareAddr,
+		AltNames:     l.altNames,
 	}
 }
 
@@ -557,6 +559,7 @@ func TestGetInterfaceConfig(t *testing.T) {
 
 func TestRenameInterface(t *testing.T) {
 	renameFailErr := fmt.Errorf("failed to rename host interface name test1 to test2")
+	removeAltNameFailErr := fmt.Errorf("failed to remove AltName test1 on interface test2: %w", testInvalidErr)
 	tests := []struct {
 		name          string
 		expectedCalls func(mockNetlink *netlinktest.MockInterfaceMockRecorder)
@@ -569,6 +572,18 @@ func TestRenameInterface(t *testing.T) {
 				mockNetlink.LinkSetDown(mockLink{name: "test1"}).Return(nil)
 				mockNetlink.LinkSetName(mockLink{name: "test1"}, "test2").Return(nil)
 				mockNetlink.LinkSetUp(mockLink{name: "test1"}).Return(nil)
+				mockNetlink.LinkByName("test2").Return(mockLink{name: "test2", altNames: []string{}}, nil)
+			},
+		},
+		{
+			name: "Rename Interface Success with AltName",
+			expectedCalls: func(mockNetlink *netlinktest.MockInterfaceMockRecorder) {
+				mockNetlink.LinkByName("test1").Return(mockLink{name: "test1"}, nil)
+				mockNetlink.LinkSetDown(mockLink{name: "test1"}).Return(nil)
+				mockNetlink.LinkSetName(mockLink{name: "test1"}, "test2").Return(nil)
+				mockNetlink.LinkSetUp(mockLink{name: "test1"}).Return(nil)
+				mockNetlink.LinkByName("test2").Return(mockLink{name: "test2", altNames: []string{"test1"}}, nil)
+				mockNetlink.LinkDelAltName(mockLink{name: "test2", altNames: []string{"test1"}}, "test1").Return(nil)
 			},
 		},
 		{
@@ -605,6 +620,18 @@ func TestRenameInterface(t *testing.T) {
 			},
 			wantErr: renameFailErr,
 		},
+		{
+			name: "Remove AltName Err",
+			expectedCalls: func(mockNetlink *netlinktest.MockInterfaceMockRecorder) {
+				mockNetlink.LinkByName("test1").Return(mockLink{name: "test1"}, nil)
+				mockNetlink.LinkSetDown(mockLink{name: "test1"}).Return(nil)
+				mockNetlink.LinkSetName(mockLink{name: "test1"}, "test2").Return(nil)
+				mockNetlink.LinkSetUp(mockLink{name: "test1"}).Return(nil)
+				mockNetlink.LinkByName("test2").Return(mockLink{name: "test2", altNames: []string{"test1"}}, nil)
+				mockNetlink.LinkDelAltName(mockLink{name: "test2", altNames: []string{"test1"}}, "test1").Return(testInvalidErr)
+			},
+			wantErr: removeAltNameFailErr,
+		},
 	}
 
 	for _, tc := range tests {

pkg/agent/util/netlink/netlink_linux.go

@@ -64,6 +64,10 @@ type Interface interface {
 
 	LinkSetName(link netlink.Link, name string) error
 
+	LinkAddAltName(link netlink.Link, name string) error
+
+	LinkDelAltName(link netlink.Link, name string) error
+
 	LinkSetUp(link netlink.Link) error
 
 	ConntrackDeleteFilter(table netlink.ConntrackTableType, family netlink.InetFamily, filter netlink.CustomConntrackFilter) (uint, error)