mirror of
https://github.com/edgelesssys/constellation.git
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314 lines
11 KiB
Go
314 lines
11 KiB
Go
package cryptmapper
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import (
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"context"
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"errors"
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"fmt"
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"io/fs"
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"os"
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"path/filepath"
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"sync"
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cryptsetup "github.com/martinjungblut/go-cryptsetup"
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"k8s.io/klog"
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mount "k8s.io/mount-utils"
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utilexec "k8s.io/utils/exec"
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)
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const (
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cryptPrefix = "/dev/mapper/"
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integritySuffix = "_dif"
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keySizeIntegrity = 96
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keySizeCrypt = 64
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)
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// packageLock is needed to block concurrent use of package functions, since libcryptsetup is not thread safe.
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// See: https://gitlab.com/cryptsetup/cryptsetup/-/issues/710
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// https://stackoverflow.com/questions/30553386/cryptsetup-backend-safe-with-multithreading
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var packageLock = sync.Mutex{}
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// CryptMapper manages dm-crypt volumes.
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type CryptMapper struct {
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mapper DeviceMapper
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kms KeyCreator
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}
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// New initializes a new CryptMapper with the given kms client and key-encryption-key ID.
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// kms is used to fetch data encryption keys for the dm-crypt volumes.
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func New(kms KeyCreator, mapper DeviceMapper) *CryptMapper {
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return &CryptMapper{
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mapper: mapper,
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kms: kms,
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}
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}
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// KeyCreator is an interface to create data encryption keys.
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type KeyCreator interface {
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GetDEK(ctx context.Context, dekID string, dekSize int) ([]byte, error)
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}
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// DeviceMapper is an interface for device mapper methods.
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type DeviceMapper interface {
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// Init initializes a crypt device backed by 'devicePath'.
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// Sets the deviceMapper to the newly allocated Device or returns any error encountered.
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// C equivalent: crypt_init
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Init(devicePath string) error
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// ActivateByVolumeKey activates a device by using a volume key.
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// Returns nil on success, or an error otherwise.
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// C equivalent: crypt_activate_by_volume_key
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ActivateByVolumeKey(deviceName, volumeKey string, volumeKeySize, flags int) error
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// Deactivate deactivates a device.
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// Returns nil on success, or an error otherwise.
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// C equivalent: crypt_deactivate
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Deactivate(deviceName string) error
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// Format formats a Device, using a specific device type, and type-independent parameters.
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// Returns nil on success, or an error otherwise.
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// C equivalent: crypt_format
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Format(deviceType cryptsetup.DeviceType, genericParams cryptsetup.GenericParams) error
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// Free releases crypt device context and used memory.
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// C equivalent: crypt_free
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Free() bool
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// Load loads crypt device parameters from the on-disk header.
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// Returns nil on success, or an error otherwise.
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// C equivalent: crypt_load
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Load(cryptsetup.DeviceType) error
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// Wipe removes existing data and clears the device for use with dm-integrity.
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// Returns nil on success, or an error otherwise.
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// C equivalent: crypt_wipe
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Wipe(devicePath string, pattern int, offset, length uint64, wipeBlockSize int, flags int, progress func(size, offset uint64) int) error
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}
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// cryptDevice is a wrapper for cryptsetup.Device.
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type CryptDevice struct {
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*cryptsetup.Device
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}
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// Init initializes a crypt device backed by 'devicePath'.
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// Sets the cryptDevice's deviceMapper to the newly allocated Device or returns any error encountered.
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// C equivalent: crypt_init.
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func (c *CryptDevice) Init(devicePath string) error {
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device, err := cryptsetup.Init(devicePath)
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if err != nil {
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return err
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}
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c.Device = device
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return nil
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}
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// Free releases crypt device context and used memory.
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// C equivalent: crypt_free.
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func (c *CryptDevice) Free() bool {
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res := c.Device.Free()
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c.Device = nil
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return res
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}
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// CloseCryptDevice closes the crypt device mapped for volumeID.
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// Returns nil if the volume does not exist.
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func (c *CryptMapper) CloseCryptDevice(volumeID string) error {
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source, err := filepath.EvalSymlinks(cryptPrefix + volumeID)
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if err != nil {
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var pathErr *fs.PathError
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if errors.As(err, &pathErr) {
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klog.V(4).Infof("Skipping unmapping for disk %q: volume does not exist or is already unmapped", volumeID)
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return nil
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}
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return fmt.Errorf("failed to get device path for disk %q: %w", cryptPrefix+volumeID, err)
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}
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if err := closeCryptDevice(c.mapper, source, volumeID, "crypt"); err != nil {
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return fmt.Errorf("failed to close crypt device: %w", err)
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}
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integrity, err := filepath.EvalSymlinks(cryptPrefix + volumeID + integritySuffix)
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if err == nil {
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// If device was created with integrity, we need to also close the integrity device
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integrityErr := closeCryptDevice(c.mapper, integrity, volumeID+integritySuffix, "integrity")
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if integrityErr != nil {
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klog.Errorf("Could not close integrity device: %s", integrityErr)
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return integrityErr
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}
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}
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if err != nil {
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var pathErr *fs.PathError
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if errors.As(err, &pathErr) {
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// integrity device does not exist
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return nil
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}
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return fmt.Errorf("failed to get device path for disk %q: %w", cryptPrefix+volumeID, err)
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}
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return nil
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}
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// closeCryptDevice closes the crypt device mapped for volumeID.
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func closeCryptDevice(device DeviceMapper, source, volumeID, deviceType string) error {
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packageLock.Lock()
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defer packageLock.Unlock()
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klog.V(4).Infof("Unmapping dm-%s volume %q for device %q", deviceType, cryptPrefix+volumeID, source)
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cryptsetup.SetLogCallback(func(level int, message string) { klog.V(4).Infof("libcryptsetup: %s", message) })
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if err := device.Init(source); err != nil {
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klog.Errorf("Could not initialize dm-%s to unmap device %q: %s", deviceType, source, err)
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return fmt.Errorf("could not initialize dm-%s to unmap device %q: %w", deviceType, source, err)
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}
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defer device.Free()
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if err := device.Deactivate(volumeID); err != nil {
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klog.Errorf("Could not deactivate dm-%s volume %q for device %q: %s", deviceType, cryptPrefix+volumeID, source, err)
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return fmt.Errorf("could not deactivate dm-%s volume %q for device %q: %w", deviceType, cryptPrefix+volumeID, source, err)
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}
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klog.V(4).Infof("Successfully unmapped dm-%s volume %q for device %q", deviceType, cryptPrefix+volumeID, source)
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return nil
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}
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// OpenCryptDevice maps the volume at source to the crypt device identified by volumeID.
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// The key used to encrypt the volume is fetched using CryptMapper's kms client.
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func (c *CryptMapper) OpenCryptDevice(ctx context.Context, source, volumeID string, integrity bool) (string, error) {
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klog.V(4).Infof("Fetching data encryption key for volume %q", volumeID)
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keySize := keySizeCrypt
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if integrity {
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keySize = keySizeIntegrity
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}
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dek, err := c.kms.GetDEK(ctx, volumeID, keySize)
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if err != nil {
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return "", err
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}
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m := &mount.SafeFormatAndMount{Exec: utilexec.New()}
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return openCryptDevice(c.mapper, source, volumeID, string(dek), integrity, m.GetDiskFormat)
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}
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// openCryptDevice maps the volume at source to the crypt device identified by volumeID.
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func openCryptDevice(device DeviceMapper, source, volumeID, dek string, integrity bool, diskInfo func(disk string) (string, error)) (string, error) {
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packageLock.Lock()
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defer packageLock.Unlock()
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var integrityType string
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keySize := len(dek)
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if integrity {
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if len(dek) != keySizeIntegrity {
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return "", fmt.Errorf("invalid key size for crypt with integrity: expected [%d], got [%d]", keySizeIntegrity, len(dek))
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}
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integrityType = "hmac(sha256)"
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}
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if !integrity && (len(dek) != keySizeCrypt) {
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return "", fmt.Errorf("invalid key length for plain crypt: expected [%d], got [%d]", keySizeCrypt, len(dek))
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}
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klog.V(4).Infof("Mapping device %q to dm-crypt volume %q", source, cryptPrefix+volumeID)
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cryptsetup.SetLogCallback(func(level int, message string) { klog.V(4).Infof("libcryptsetup: %s", message) })
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// Initialize the block device
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if err := device.Init(source); err != nil {
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klog.Errorf("Initializing dm-crypt to map device %q: %s", source, err)
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return "", fmt.Errorf("initializing dm-crypt to map device %q: %w", source, err)
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}
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defer device.Free()
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needWipe := false
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// Try to load LUKS headers
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// If this fails, the device is either not formatted at all, or already formatted with a different FS
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if err := device.Load(nil); err != nil {
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klog.V(4).Infof("Device %q is not formatted as LUKS2 partition, checking for existing format...", source)
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format, err := diskInfo(source)
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if err != nil {
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return "", fmt.Errorf("could not determine if disk is formatted: %w", err)
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}
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if format != "" {
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// Device is already formated, return an error
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klog.Errorf("Disk %q is already formatted as: %s", source, format)
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return "", fmt.Errorf("disk %q is already formatted as: %s", source, format)
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}
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// Device is not formatted, so we can safely create a new LUKS2 partition
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klog.V(4).Infof("Device %q is not formatted. Creating new LUKS2 partition...", source)
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if err := device.Format(
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cryptsetup.LUKS2{
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SectorSize: 4096,
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Integrity: integrityType,
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PBKDFType: &cryptsetup.PbkdfType{
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// Use low memory recommendation from https://datatracker.ietf.org/doc/html/rfc9106#section-7
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Type: "argon2id",
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TimeMs: 2000,
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Iterations: 3,
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ParallelThreads: 4,
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MaxMemoryKb: 65536, // ~64MiB
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},
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},
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cryptsetup.GenericParams{
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Cipher: "aes",
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CipherMode: "xts-plain64",
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VolumeKey: dek,
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VolumeKeySize: keySize,
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}); err != nil {
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klog.Errorf("Formatting device %q failed: %s", source, err)
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return "", fmt.Errorf("formatting device %q failed: %w", source, err)
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}
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needWipe = true
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}
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if integrity && needWipe {
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if err := performWipe(device, volumeID, dek); err != nil {
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return "", fmt.Errorf("wiping device: %w", err)
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}
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}
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klog.V(4).Infof("Activating LUKS2 device %q", cryptPrefix+volumeID)
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if err := device.ActivateByVolumeKey(volumeID, dek, keySize, 0); err != nil {
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klog.Errorf("Trying to activate dm-crypt volume: %s", err)
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return "", fmt.Errorf("trying to activate dm-crypt volume: %w", err)
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}
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klog.V(4).Infof("Device %q successfully mapped to dm-crypt volume %q", source, cryptPrefix+volumeID)
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return cryptPrefix + volumeID, nil
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}
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// performWipe handles setting up parameters and clearing the device for dm-integrity.
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func performWipe(device DeviceMapper, volumeID, dek string) error {
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klog.V(4).Infof("Preparing device for dm-integrity. This may take while...")
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tmpDevice := "temporary-cryptsetup-" + volumeID
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// Active as temporary device
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if err := device.ActivateByVolumeKey(tmpDevice, dek, len(dek), (cryptsetup.CRYPT_ACTIVATE_PRIVATE | cryptsetup.CRYPT_ACTIVATE_NO_JOURNAL)); err != nil {
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klog.Errorf("Trying to activate temporary dm-crypt volume: %s", err)
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return fmt.Errorf("trying to activate temporary dm-crypt volume: %w", err)
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}
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// Set progress callbacks
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var progressCallback func(size, offset uint64) int
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if fileInfo, _ := os.Stdout.Stat(); (fileInfo.Mode() & os.ModeCharDevice) != 0 {
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// If we are printing to a terminal we can show continues updates
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progressCallback = func(size, offset uint64) int {
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prog := (float64(offset) / float64(size)) * 100
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fmt.Printf("\033[2K\rWipe in progress: %.2f%%", prog)
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return 0
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}
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} else {
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// No terminal available, disable callbacks to not fill up logs with large amount of progress updates
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klog.V(4).Info("Progress updates not available")
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progressCallback = nil
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}
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// Wipe the device using the same options as used in cryptsetup: https://gitlab.com/cryptsetup/cryptsetup/-/blob/master/src/cryptsetup.c#L1178
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if err := device.Wipe(cryptPrefix+tmpDevice, cryptsetup.CRYPT_WIPE_ZERO, 0, 0, 1024*1024, 0, progressCallback); err != nil {
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return err
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}
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fmt.Println()
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// Deactivate the temporary device
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if err := device.Deactivate(tmpDevice); err != nil {
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klog.Errorf("Deactivating temporary volume: %s", err)
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return fmt.Errorf("deactivating temporary volume: %w", err)
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}
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klog.V(4).Info("dm-integrity successfully initiated")
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return nil
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}
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