Allow opening LUKS containers inside linsk ls

cmd/flags.go

@@ -0,0 +1,74 @@
+// Linsk - A utility to access Linux-native file systems on non-Linux operating systems.
+// Copyright (c) 2023 The Linsk Authors.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+package cmd
+
+import (
+	"log/slog"
+	"os"
+
+	"github.com/spf13/pflag"
+)
+
+const defaultVMMountDevName = "vdb"
+
+func getLUKSContainerDevice() string {
+	var luksContainerDevice string
+
+	if vmRuntimeLUKSContainerFlag != "" {
+		if vmRuntimeLUKSContainerEntireDriveFlag {
+			slog.Error("--luks-container and --luks-container-entire-drive (-c) cannot be both specified at once")
+			os.Exit(1)
+		}
+
+		luksContainerDevice = vmRuntimeLUKSContainerFlag
+	} else if vmRuntimeLUKSContainerEntireDriveFlag {
+		luksContainerDevice = defaultVMMountDevName
+	}
+
+	return luksContainerDevice
+}
+
+var (
+	vmRuntimeLUKSContainerFlag            string
+	vmRuntimeLUKSContainerEntireDriveFlag bool
+
+	// These are for internal use by the initVMRuntimeFlags and configureVMRuntimeFlags functions.
+	vmRuntimeInternalAllowLUKSLowMemoryFlag bool
+
+	// These are to be initialized (set) by the initVMRuntimeFlags function.
+	vmRuntimeLUKSContainerDevice string
+)
+
+func initVMRuntimeFlags(flags *pflag.FlagSet) {
+	flags.StringVar(&vmRuntimeLUKSContainerFlag, "luks-container", "", `Specifies a device path (without "dev/" prefix) to preopen as a LUKS container (password will be prompted). Useful for accessing LVM partitions behind LUKS.`)
+	flags.BoolVarP(&vmRuntimeLUKSContainerEntireDriveFlag, "luks-container-entire-drive", "c", false, `Similar to --luks-container, but this assumes that the entire passed-through volume is a LUKS container (password will be prompted).`)
+	flags.BoolVar(&vmRuntimeInternalAllowLUKSLowMemoryFlag, "allow-luks-low-memory", false, "Allow VM memory allocation lower than 2048 MiB when LUKS is enabled.")
+}
+
+func configureVMRuntimeFlags() {
+	vmRuntimeLUKSContainerDevice = getLUKSContainerDevice()
+
+	if (luksFlag || vmRuntimeLUKSContainerDevice != "") && !vmRuntimeInternalAllowLUKSLowMemoryFlag {
+		if vmMemAllocFlag < defaultMemAllocLUKS {
+			if vmMemAllocFlag != defaultMemAlloc {
+				slog.Warn("Enforcing minimum LUKS memory allocation. Please add --allow-luks-low-memory to disable this.", "min", vmMemAllocFlag, "specified", vmMemAllocFlag)
+			}
+
+			vmMemAllocFlag = defaultMemAllocLUKS
+		}
+	}
+}

cmd/ls.go

@@ -32,7 +32,17 @@ var lsCmd = &cobra.Command{
 	Short: "Start a VM and list all user drives within the VM. Uses lsblk command under the hood.",
 	Args:  cobra.ExactArgs(1),
 	Run: func(cmd *cobra.Command, args []string) {
+		configureVMRuntimeFlags()
+
 		os.Exit(runVM(args[0], func(ctx context.Context, i *vm.VM, fm *vm.FileManager, trc *share.NetTapRuntimeContext) int {
+			if vmRuntimeLUKSContainerDevice != "" {
+				err := fm.PreopenLUKSContainer(vmRuntimeLUKSContainerDevice)
+				if err != nil {
+					slog.Error("Failed to preopen LUKS container", "error", err.Error())
+					return 1
+				}
+			}
+
 			lsblkOut, err := fm.Lsblk()
 			if err != nil {
 				slog.Error("Failed to list block devices in the VM", "error", err.Error())
@@ -49,3 +59,7 @@ var lsCmd = &cobra.Command{
 		}, nil, false, false))
 	},
 }
+
+func init() {
+	initVMRuntimeFlags(lsCmd.Flags())
+}

cmd/run.go

@@ -35,24 +35,13 @@ var runCmd = &cobra.Command{
 	Short: "Start a VM and expose an FTP file share.",
 	Args:  cobra.RangeArgs(1, 3),
 	Run: func(cmd *cobra.Command, args []string) {
-		var luksContainerDevice string
+		configureVMRuntimeFlags()
 
-		vmMountDevName := "vdb"
+		vmMountDevName := defaultVMMountDevName
-
-		if luksContainerFlag != "" {
-			if luksContainerEntireDriveFlag {
-				slog.Error("--luks-container and --luks-container-entire-drive (-c) cannot be both specified at once")
-				os.Exit(1)
-			}
-
-			luksContainerDevice = luksContainerFlag
-		} else if luksContainerEntireDriveFlag {
-			luksContainerDevice = vmMountDevName
-		}
 
 		if len(args) > 1 {
 			vmMountDevName = args[1]
-		} else if luksContainerDevice != "" {
+		} else if vmRuntimeLUKSContainerDevice != "" {
 			slog.Error("Cannot use the default (entire) device with a LUKS container. Please specify the in-VM device name to mount as a second positional argument.")
 		}
 
@@ -84,16 +73,6 @@ var runCmd = &cobra.Command{
 			os.Exit(1)
 		}
 
-		if (luksFlag || luksContainerDevice != "") && !allowLUKSLowMemoryFlag {
-			if vmMemAllocFlag < defaultMemAllocLUKS {
-				if vmMemAllocFlag != defaultMemAlloc {
-					slog.Warn("Enforcing minimum LUKS memory allocation. Please add --allow-luks-low-memory to disable this.", "min", vmMemAllocFlag, "specified", vmMemAllocFlag)
-				}
-
-				vmMemAllocFlag = defaultMemAllocLUKS
-			}
-		}
-
 		os.Exit(runVM(args[0], func(ctx context.Context, i *vm.VM, fm *vm.FileManager, tapCtx *share.NetTapRuntimeContext) int {
 			fsToLog := "<auto>"
 			if fsTypeOverride != "" {
@@ -103,7 +82,7 @@ var runCmd = &cobra.Command{
 			slog.Info("Mounting the device", "dev", vmMountDevName, "fs", fsToLog, "luks", luksFlag)
 
 			err := fm.Mount(vmMountDevName, vm.MountOptions{
-				LUKSContainerPreopen: luksContainerDevice,
+				LUKSContainerPreopen: vmRuntimeLUKSContainerDevice,
 
 				FSTypeOverride: fsTypeOverride,
 				LUKS:           luksFlag,
@@ -157,24 +136,20 @@ var runCmd = &cobra.Command{
 }
 
 var (
-	luksFlag                     bool
+	luksFlag             bool
-	luksContainerFlag            string
+	shareListenIPFlag    string
-	luksContainerEntireDriveFlag bool
+	ftpExtIPFlag         string
-	allowLUKSLowMemoryFlag       bool
+	shareBackendFlag     string
-	shareListenIPFlag            string
+	smbUseExternAddrFlag bool
-	ftpExtIPFlag                 string
+	debugShellFlag       bool
-	shareBackendFlag             string
-	smbUseExternAddrFlag         bool
-	debugShellFlag               bool
 )
 
 func init() {
 	runCmd.Flags().BoolVarP(&luksFlag, "luks", "l", false, "Use cryptsetup to open a LUKS volume (password will be prompted).")
-	runCmd.Flags().StringVar(&luksContainerFlag, "luks-container", "", `Specifies a device path (without "dev/" prefix) to preopen as a LUKS container (password will be prompted). Useful for accessing LVM partitions behind LUKS.`)
-	runCmd.Flags().BoolVarP(&luksContainerEntireDriveFlag, "luks-container-entire-drive", "c", false, `Similar to --luks-container, but this assumes that the entire passed-through volume is a LUKS container (password will be prompted).`)
-	runCmd.Flags().BoolVar(&allowLUKSLowMemoryFlag, "allow-luks-low-memory", false, "Allow VM memory allocation lower than 2048 MiB when LUKS is enabled.")
 	runCmd.Flags().BoolVar(&debugShellFlag, "debug-shell", false, "Start a VM shell when the network file share is active.")
 
+	initVMRuntimeFlags(runCmd.Flags())
+
 	var defaultShareType string
 	switch {
 	case osspecifics.IsMacOS():

vm/filemanager.go

@@ -169,6 +169,39 @@ func (fm *FileManager) luksOpen(sc *ssh.Client, fullDevPath string, luksDMName s
 	})
 }
 
+func (fm *FileManager) PreopenLUKSContainer(containerDevPath string) error {
+	sc, err := fm.vm.DialSSH()
+	if err != nil {
+		return errors.Wrap(err, "dial vm ssh")
+	}
+
+	defer func() { _ = sc.Close() }()
+
+	return fm.preopenLUKSContainerWithSSH(sc, containerDevPath)
+}
+
+func (fm *FileManager) preopenLUKSContainerWithSSH(sc *ssh.Client, containerDevPath string) error {
+	if !utils.ValidateDevName(containerDevPath) {
+		return fmt.Errorf("bad luks container device name")
+	}
+
+	fullContainerDevPath := "/dev/" + containerDevPath
+
+	fm.logger.Info("Preopening a LUKS container", "container", fullContainerDevPath)
+
+	err := fm.luksOpen(sc, fullContainerDevPath, "cryptcontainer")
+	if err != nil {
+		return errors.Wrap(err, "luks (pre)open container")
+	}
+
+	err = fm.InitLVM()
+	if err != nil {
+		return errors.Wrap(err, "reinit lvm")
+	}
+
+	return nil
+}
+
 func (fm *FileManager) Mount(devName string, mo MountOptions) error {
 	if devName == "" {
 		return fmt.Errorf("device name is empty")
@@ -204,22 +237,9 @@ func (fm *FileManager) Mount(devName string, mo MountOptions) error {
 	defer func() { _ = sc.Close() }()
 
 	if mo.LUKSContainerPreopen != "" {
-		if !utils.ValidateDevName(mo.LUKSContainerPreopen) {
+		err := fm.preopenLUKSContainerWithSSH(sc, mo.LUKSContainerPreopen)
-			return fmt.Errorf("bad luks container device name")
-		}
-
-		fullContainerDevPath := "/dev/" + mo.LUKSContainerPreopen
-
-		fm.logger.Info("Preopening a LUKS container", "container", fullContainerDevPath)
-
-		err := fm.luksOpen(sc, fullContainerDevPath, "cryptcontainer")
 		if err != nil {
-			return errors.Wrap(err, "luks (pre)open container")
+			return errors.Wrap(err, "preopen luks container")
-		}
-
-		err = fm.InitLVM()
-		if err != nil {
-			return errors.Wrap(err, "reinit lvm")
 		}
 	}