Allow to use file descriptors with virtio-serial and virtio-net

doc/usage.md

@@ -135,19 +135,26 @@ The `--device virtio-net` option adds a network interface to the virtual machine
 
 #### Arguments
 - `mac`: optional argument to specify the MAC address of the VM. If it's omitted, a random MAC address will be used.
+- `fd`: file descriptor to attach to the guest network interface. The file descriptor must be a connected datagram socket. See [VZFileHandleNetworkDeviceAttachment](https://developer.apple.com/documentation/virtualization/vzfilehandlenetworkdeviceattachment?language=objc) for more details.
+- `nat`: guest network traffic will be NAT'ed through the host. This is the default. See [VZNATNetworkDeviceAttachment](https://developer.apple.com/documentation/virtualization/vznatnetworkdeviceattachment?language=objc) for more details.
+- `unixSocketPath: path to a unix socket to attach to the guest network interface. See See [VZFileHandleNetworkDeviceAttachment](https://developer.apple.com/documentation/virtualization/vzfilehandlenetworkdeviceattachment?language=objc) for more details.
+
+`fd`, `nat`, `unixSocketPath` are mutually exclusive.
 
 #### Example
-`--device virtio-net,mac=52:54:00:70:2b:71`
+`--device virtio-net,nat,mac=52:54:00:70:2b:71`
 
 
 ### Serial Port
 
 #### Description
 
 The `--device virtio-serial` option adds a serial device to the virtual machine. This is useful to redirect text output from the virtual machine to a log file.
+The `logFilePath` and `stdio` arguments are mutually exclusive.
 
 #### Arguments
 - `logFilePath`: path where the serial port output should be written.
+- `stdio`: uses stdin/stdout for the serial console input/output.
 
 #### Example
 `--device virtio-serial,logFilePath=/Users/virtuser/vfkit.log`

go.mod

@@ -3,7 +3,7 @@ module github.com/crc-org/vfkit
 go 1.17
 
 require (
-	github.com/Code-Hex/vz/v3 v3.0.0
+	github.com/Code-Hex/vz/v3 v3.0.4
 	github.com/docker/go-units v0.4.0
 	github.com/h2non/filetype v1.1.3
 	github.com/prashantgupta24/mac-sleep-notifier v1.0.1
@@ -19,7 +19,7 @@ require (
 	github.com/inconshreveable/mousetrap v1.0.1 // indirect
 	github.com/kr/pretty v0.2.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	golang.org/x/mod v0.7.0 // indirect
+	golang.org/x/mod v0.9.0 // indirect
 	golang.org/x/sys v0.3.0 // indirect
 	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect

go.sum

@@ -1,5 +1,5 @@
-github.com/Code-Hex/vz/v3 v3.0.0 h1:UuYAZz8NF8n+R4MLfn/lpUlepgzZ8BlhKtioQ+q9LXk=
-github.com/Code-Hex/vz/v3 v3.0.0/go.mod h1:+xPQOXVzNaZ4OeIIhlJFumtbFhsvRfqKwX7wuZS4dFA=
+github.com/Code-Hex/vz/v3 v3.0.4 h1:oB74JSjSdIijjHkoYWG5ws7bHpx69m1w3PopFQdjFSc=
+github.com/Code-Hex/vz/v3 v3.0.4/go.mod h1:+xPQOXVzNaZ4OeIIhlJFumtbFhsvRfqKwX7wuZS4dFA=
 github.com/armon/go-proxyproto v0.0.0-20210323213023-7e956b284f0a/go.mod h1:QmP9hvJ91BbJmGVGSbutW19IC0Q9phDCLGaomwTJbgU=
 github.com/cpuguy83/go-md2man/v2 v2.0.2/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
@@ -43,8 +43,8 @@ golang.org/x/crypto v0.1.0 h1:MDRAIl0xIo9Io2xV565hzXHw3zVseKrJKodhohM5CjU=
 golang.org/x/crypto v0.1.0/go.mod h1:RecgLatLF4+eUMCP1PoPZQb+cVrJcOPbHkTkbkB9sbw=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
 golang.org/x/mod v0.6.0/go.mod h1:4mET923SAdbXp2ki8ey+zGs1SLqsuM2Y0uvdZR/fUNI=
-golang.org/x/mod v0.7.0 h1:LapD9S96VoQRhi/GrNTqeBJFrUjs5UHCAtTlgwA5oZA=
-golang.org/x/mod v0.7.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
+golang.org/x/mod v0.9.0 h1:KENHtAZL2y3NLMYZeHY9DW8HW8V+kQyJsY/V9JlKvCs=
+golang.org/x/mod v0.9.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=

pkg/config/config.go

@@ -2,6 +2,8 @@ package config
 
 import (
 	"fmt"
+	"os"
+	"os/exec"
 	"strconv"
 	"strings"
 )
@@ -75,6 +77,36 @@ func (vm *VirtualMachine) ToCmdLine() ([]string, error) {
 	return args, nil
 }
 
+func (vm *VirtualMachine) extraFiles() []*os.File {
+	extraFiles := []*os.File{}
+	for _, dev := range vm.Devices {
+		virtioNet, ok := dev.(*VirtioNet)
+		if !ok {
+			continue
+		}
+		if virtioNet.Socket != nil {
+			extraFiles = append(extraFiles, virtioNet.Socket)
+		}
+	}
+
+	return extraFiles
+}
+
+// Cmd creates an exec.Cmd to start vfkit with the configured devices.
+// In particular it will set ExtraFiles appropriately when mapping
+// a file with a network interface.
+func (vm *VirtualMachine) Cmd(vfkitPath string) (*exec.Cmd, error) {
+	args, err := vm.ToCmdLine()
+	if err != nil {
+		return nil, err
+	}
+
+	cmd := exec.Command(vfkitPath, args...)
+	cmd.ExtraFiles = vm.extraFiles()
+
+	return cmd, nil
+}
+
 func (vm *VirtualMachine) AddDevicesFromCmdLine(cmdlineOpts []string) error {
 	for _, deviceOpts := range cmdlineOpts {
 		dev, err := deviceFromCmdLine(deviceOpts)

pkg/config/virtio.go

@@ -3,6 +3,7 @@ package config
 import (
 	"fmt"
 	"net"
+	"os"
 	"strconv"
 	"strings"
 )
@@ -42,18 +43,21 @@ type VirtioRng struct {
 // TODO: Add BridgedNetwork support
 // https://github.com/Code-Hex/vz/blob/d70a0533bf8ed0fa9ab22fa4d4ca554b7c3f3ce5/network.go#L81-L82
 
-// TODO: Add FileHandleNetwork support
-// https://github.com/Code-Hex/vz/blob/d70a0533bf8ed0fa9ab22fa4d4ca554b7c3f3ce5/network.go#L109-L112
-
 // VirtioNet configures the virtual machine networking.
 type VirtioNet struct {
 	Nat        bool
 	MacAddress net.HardwareAddr
+	// file parameter is holding a connected datagram socket.
+	// see https://github.com/Code-Hex/vz/blob/7f648b6fb9205d6f11792263d79876e3042c33ec/network.go#L113-L155
+	Socket *os.File
+
+	UnixSocketPath string
 }
 
 // VirtioSerial configures the virtual machine serial ports.
 type VirtioSerial struct {
-	LogFile string
+	LogFile   string
+	UsesStdio bool
 }
 
 // TODO: Add VirtioBalloon
@@ -131,10 +135,31 @@ func VirtioSerialNew(logFilePath string) (VirtioDevice, error) {
 	}, nil
 }
 
+func VirtioSerialNewStdio() (VirtioDevice, error) {
+	return &VirtioSerial{
+		UsesStdio: true,
+	}, nil
+}
+
+func (dev *VirtioSerial) validate() error {
+	if dev.LogFile != "" && dev.UsesStdio {
+		return fmt.Errorf("'logFilePath' and 'stdio' cannot be set at the same time")
+	}
+	if dev.LogFile == "" && !dev.UsesStdio {
+		return fmt.Errorf("One of 'logFilePath' or 'stdio' must be set")
+	}
+
+	return nil
+}
+
 func (dev *VirtioSerial) ToCmdLine() ([]string, error) {
-	if dev.LogFile == "" {
-		return nil, fmt.Errorf("virtio-serial needs the path to the log file")
+	if err := dev.validate(); err != nil {
+		return nil, err
+	}
+	if dev.UsesStdio {
+		return []string{"--device", "virtio-serial,stdio"}, nil
 	}
+
 	return []string{"--device", fmt.Sprintf("virtio-serial,logFilePath=%s", dev.LogFile)}, nil
 }
 
@@ -143,16 +168,22 @@ func (dev *VirtioSerial) FromOptions(options []option) error {
 		switch option.key {
 		case "logFilePath":
 			dev.LogFile = option.value
+		case "stdio":
+			if option.value != "" {
+				return fmt.Errorf("Unexpected value for virtio-serial 'stdio' option: %s", option.value)
+			}
+			dev.UsesStdio = true
 		default:
 			return fmt.Errorf("Unknown option for virtio-serial devices: %s", option.key)
 		}
 	}
-	return nil
+
+	return dev.validate()
 }
 
 // VirtioNetNew creates a new network device for the virtual machine. It will
 // use macAddress as its MAC address.
-func VirtioNetNew(macAddress string) (VirtioDevice, error) {
+func VirtioNetNew(macAddress string) (*VirtioNet, error) {
 	var hwAddr net.HardwareAddr
 
 	if macAddress != "" {
@@ -167,13 +198,54 @@ func VirtioNetNew(macAddress string) (VirtioDevice, error) {
 	}, nil
 }
 
+// Set the socket to use for the network communication
+//
+// This maps the virtual machine network interface to a connected datagram
+// socket. This means all network traffic on this interface will go through
+// file.
+// file must be a connected datagram (SOCK_DGRAM) socket.
+func (dev *VirtioNet) SetSocket(file *os.File) {
+	dev.Socket = file
+	dev.Nat = false
+}
+
+func (dev *VirtioNet) SetUnixSocketPath(path string) {
+	dev.UnixSocketPath = path
+	dev.Nat = false
+}
+
+func (dev *VirtioNet) validate() error {
+	if dev.Nat && dev.Socket != nil {
+		return fmt.Errorf("'nat' and 'fd' cannot be set at the same time")
+	}
+	if dev.Nat && dev.UnixSocketPath != "" {
+		return fmt.Errorf("'nat' and 'unixSocketPath' cannot be set at the same time")
+	}
+	if dev.Socket != nil && dev.UnixSocketPath != "" {
+		return fmt.Errorf("'fd' and 'unixSocketPath' cannot be set at the same time")
+	}
+	if !dev.Nat && dev.Socket == nil && dev.UnixSocketPath == "" {
+		return fmt.Errorf("One of 'nat' or 'fd' or 'unixSocketPath' must be set")
+	}
+
+	return nil
+}
+
 func (dev *VirtioNet) ToCmdLine() ([]string, error) {
-	if !dev.Nat {
-		return nil, fmt.Errorf("virtio-net only support 'nat' networking")
+	if err := dev.validate(); err != nil {
+		return nil, err
 	}
+
 	builder := strings.Builder{}
 	builder.WriteString("virtio-net")
-	builder.WriteString(",nat")
+	if dev.Nat {
+		builder.WriteString(",nat")
+	} else if dev.UnixSocketPath != "" {
+		fmt.Fprintf(&builder, ",unixSocketPath=%s", dev.UnixSocketPath)
+	} else {
+		fmt.Fprintf(&builder, ",fd=%d", dev.Socket.Fd())
+	}
+
 	if len(dev.MacAddress) != 0 {
 		builder.WriteString(fmt.Sprintf(",mac=%s", dev.MacAddress))
 	}
@@ -195,11 +267,20 @@ func (dev *VirtioNet) FromOptions(options []option) error {
 				return err
 			}
 			dev.MacAddress = macAddress
+		case "fd":
+			fd, err := strconv.Atoi(option.value)
+			if err != nil {
+				return err
+			}
+			dev.Socket = os.NewFile(uintptr(fd), "vfkit virtio-net socket")
+		case "unixSocketPath":
+			dev.UnixSocketPath = option.value
 		default:
 			return fmt.Errorf("Unknown option for virtio-net devices: %s", option.key)
 		}
 	}
-	return nil
+
+	return dev.validate()
 }
 
 // VirtioRngNew creates a new random number generator device to feed entropy

pkg/config/virtio_test.go

@@ -91,13 +91,35 @@ var virtioDevTests = map[string]virtioDevTest{
 		},
 		expectedCmdLine: []string{"--device", "virtio-serial,logFilePath=/foo/bar.log"},
 	},
+	"NewVirtioSerialStdio": {
+		newDev: func() (VirtioDevice, error) { return VirtioSerialNewStdio() },
+		expectedDev: &VirtioSerial{
+                        UsesStdio: true,
+		},
+		expectedCmdLine: []string{"--device", "virtio-serial,stdio"},
+	},
 	"NewVirtioNet": {
 		newDev: func() (VirtioDevice, error) { return VirtioNetNew("") },
 		expectedDev: &VirtioNet{
 			Nat: true,
 		},
 		expectedCmdLine: []string{"--device", "virtio-net,nat"},
 	},
+	"NewVirtioNetWithPath": {
+		newDev: func() (VirtioDevice, error) {
+			dev, err := VirtioNetNew("")
+			if err != nil {
+				return nil, err
+			}
+			dev.SetUnixSocketPath("/tmp/unix.sock")
+			return dev, nil
+		},
+		expectedDev: &VirtioNet{
+			Nat:            false,
+			UnixSocketPath: "/tmp/unix.sock",
+		},
+		expectedCmdLine: []string{"--device", "virtio-net,unixSocketPath=/tmp/unix.sock"},
+	},
 	"NewVirtioNetWithMacAddress": {
 		newDev: func() (VirtioDevice, error) { return VirtioNetNew("00:11:22:33:44:55") },
 		expectedDev: &VirtioNet{