constellation/csi/cryptmapper/cryptmapper.go
Daniel Weiße 68ce23b909
Enable cryptsetup read/write workqueue bypass (#1150)
Signed-off-by: Daniel Weiße <dw@edgeless.systems>
2023-02-08 12:01:14 +01:00

407 lines
14 KiB
Go

/*
Copyright (c) Edgeless Systems GmbH
SPDX-License-Identifier: AGPL-3.0-only
*/
// Package cryptmapper provides a wrapper around libcryptsetup to manage dm-crypt volumes for CSI drivers.
package cryptmapper
import (
"context"
"errors"
"fmt"
"io/fs"
"path/filepath"
"strings"
"sync"
"time"
"github.com/edgelesssys/constellation/v2/internal/crypto"
ccryptsetup "github.com/edgelesssys/constellation/v2/internal/cryptsetup"
cryptsetup "github.com/martinjungblut/go-cryptsetup"
mount "k8s.io/mount-utils"
utilexec "k8s.io/utils/exec"
)
const (
// LUKSHeaderSize is the amount of bytes taken up by the header of a LUKS2 partition.
// The header is 16MiB (1048576 Bytes * 16).
LUKSHeaderSize = 16777216
cryptPrefix = "/dev/mapper/"
integritySuffix = "_dif"
integrityFSSuffix = "-integrity"
keySizeIntegrity = 96
keySizeCrypt = 64
)
// packageLock is needed to block concurrent use of package functions, since libcryptsetup is not thread safe.
// See: https://gitlab.com/cryptsetup/cryptsetup/-/issues/710
//
// https://stackoverflow.com/questions/30553386/cryptsetup-backend-safe-with-multithreading
var packageLock = sync.Mutex{}
func init() {
cryptsetup.SetDebugLevel(cryptsetup.CRYPT_LOG_NORMAL)
cryptsetup.SetLogCallback(func(_ int, message string) { fmt.Printf("libcryptsetup: %s\n", message) })
}
// KeyCreator is an interface to create data encryption keys.
type KeyCreator interface {
GetDEK(ctx context.Context, dekID string, dekSize int) ([]byte, error)
}
// DeviceMapper is an interface for device mapper methods.
type DeviceMapper interface {
// Init initializes a crypt device backed by 'devicePath'.
// Sets the deviceMapper to the newly allocated Device or returns any error encountered.
Init(devicePath string) error
// InitByName initializes a crypt device from provided active device 'name'.
// Sets the deviceMapper to the newly allocated Device or returns any error encountered.
InitByName(name string) error
// ActivateByPassphrase activates a device by using a passphrase from a specific keyslot.
// Returns nil on success, or an error otherwise.
ActivateByPassphrase(deviceName string, keyslot int, passphrase string, flags int) error
// ActivateByVolumeKey activates a device by using a volume key.
// Returns nil on success, or an error otherwise.
ActivateByVolumeKey(deviceName string, volumeKey string, volumeKeySize int, flags int) error
// Deactivate deactivates a device.
// Returns nil on success, or an error otherwise.
Deactivate(deviceName string) error
// Format formats a Device, using a specific device type, and type-independent parameters.
// Returns nil on success, or an error otherwise.
Format(deviceType cryptsetup.DeviceType, genericParams cryptsetup.GenericParams) error
// Free releases crypt device context and used memory.
Free() bool
// GetDeviceName gets the path to the underlying device.
GetDeviceName() string
// GetUUID gets the devices UUID
GetUUID() string
// Load loads crypt device parameters from the on-disk header.
// Returns nil on success, or an error otherwise.
Load(cryptsetup.DeviceType) error
// KeyslotAddByVolumeKey adds a key slot using a volume key to perform the required security check.
// Returns nil on success, or an error otherwise.
KeyslotAddByVolumeKey(keyslot int, volumeKey string, passphrase string) error
// Wipe removes existing data and clears the device for use with dm-integrity.
// Returns nil on success, or an error otherwise.
Wipe(devicePath string, pattern int, offset, length uint64, wipeBlockSize int, flags int, progress func(size, offset uint64) int) error
// Resize the crypt device.
// Returns nil on success, or an error otherwise.
Resize(name string, newSize uint64) error
}
// CryptDevice is a wrapper for cryptsetup.Device.
type CryptDevice struct {
*cryptsetup.Device
}
// Init initializes a crypt device backed by 'devicePath'.
// Sets the cryptDevice's deviceMapper to the newly allocated Device or returns any error encountered.
func (c *CryptDevice) Init(devicePath string) error {
device, err := cryptsetup.Init(devicePath)
if err != nil {
return err
}
c.Device = device
return nil
}
// InitByName initializes a crypt device from provided active device 'name'.
// Sets the deviceMapper to the newly allocated Device or returns any error encountered.
func (c *CryptDevice) InitByName(name string) error {
device, err := cryptsetup.InitByName(name)
if err != nil {
return err
}
c.Device = device
return nil
}
// Free releases crypt device context and used memory.
func (c *CryptDevice) Free() bool {
res := c.Device.Free()
c.Device = nil
return res
}
// CryptMapper manages dm-crypt volumes.
type CryptMapper struct {
mapper DeviceMapper
kms KeyCreator
}
// New initializes a new CryptMapper with the given kms client and key-encryption-key ID.
// kms is used to fetch data encryption keys for the dm-crypt volumes.
func New(kms KeyCreator, mapper DeviceMapper) *CryptMapper {
return &CryptMapper{
mapper: mapper,
kms: kms,
}
}
// CloseCryptDevice closes the crypt device mapped for volumeID.
// Returns nil if the volume does not exist.
func (c *CryptMapper) CloseCryptDevice(volumeID string) error {
source, err := filepath.EvalSymlinks(cryptPrefix + volumeID)
if err != nil {
var pathErr *fs.PathError
if errors.As(err, &pathErr) {
return nil
}
return fmt.Errorf("getting device path for disk %q: %w", cryptPrefix+volumeID, err)
}
if err := closeCryptDevice(c.mapper, source, volumeID, "crypt"); err != nil {
return fmt.Errorf("closing crypt device: %w", err)
}
integrity, err := filepath.EvalSymlinks(cryptPrefix + volumeID + integritySuffix)
if err == nil {
// If device was created with integrity, we need to also close the integrity device
integrityErr := closeCryptDevice(c.mapper, integrity, volumeID+integritySuffix, "integrity")
if integrityErr != nil {
return integrityErr
}
}
if err != nil {
var pathErr *fs.PathError
if errors.As(err, &pathErr) {
// integrity device does not exist
return nil
}
return fmt.Errorf("getting device path for disk %q: %w", cryptPrefix+volumeID, err)
}
return nil
}
// OpenCryptDevice maps the volume at source to the crypt device identified by volumeID.
// The key used to encrypt the volume is fetched using CryptMapper's kms client.
func (c *CryptMapper) OpenCryptDevice(ctx context.Context, source, volumeID string, integrity bool) (string, error) {
m := &mount.SafeFormatAndMount{Exec: utilexec.New()}
return openCryptDevice(ctx, c.mapper, source, volumeID, integrity, c.kms.GetDEK, m.GetDiskFormat)
}
// ResizeCryptDevice resizes the underlying crypt device and returns the mapped device path.
func (c *CryptMapper) ResizeCryptDevice(ctx context.Context, volumeID string) (string, error) {
if err := resizeCryptDevice(ctx, c.mapper, volumeID, c.kms.GetDEK); err != nil {
return "", err
}
return cryptPrefix + volumeID, nil
}
// GetDevicePath returns the device path of a mapped crypt device.
func (c *CryptMapper) GetDevicePath(volumeID string) (string, error) {
return getDevicePath(c.mapper, strings.TrimPrefix(volumeID, cryptPrefix))
}
// closeCryptDevice closes the crypt device mapped for volumeID.
func closeCryptDevice(device DeviceMapper, source, volumeID, deviceType string) error {
packageLock.Lock()
defer packageLock.Unlock()
if err := device.InitByName(volumeID); err != nil {
return fmt.Errorf("initializing dm-%s to unmap device %q: %w", deviceType, source, err)
}
defer device.Free()
if err := device.Deactivate(volumeID); err != nil {
return fmt.Errorf("deactivating dm-%s volume %q for device %q: %w", deviceType, cryptPrefix+volumeID, source, err)
}
return nil
}
// openCryptDevice maps the volume at source to the crypt device identified by volumeID.
func openCryptDevice(ctx context.Context, device DeviceMapper, source, volumeID string, integrity bool,
getKey func(ctx context.Context, keyID string, keySize int) ([]byte, error), diskInfo func(disk string) (string, error),
) (string, error) {
packageLock.Lock()
defer packageLock.Unlock()
var integrityType string
keySize := keySizeCrypt
if integrity {
integrityType = "hmac(sha256)"
keySize = keySizeIntegrity
}
// Initialize the block device
if err := device.Init(source); err != nil {
return "", fmt.Errorf("initializing dm-crypt to map device %q: %w", source, err)
}
defer device.Free()
var passphrase []byte
// Try to load LUKS headers
// If this fails, the device is either not formatted at all, or already formatted with a different FS
if err := device.Load(cryptsetup.LUKS2{}); err != nil {
format, err := diskInfo(source)
if err != nil {
return "", fmt.Errorf("determining if disk is formatted: %w", err)
}
if format != "" {
return "", fmt.Errorf("disk %q is already formatted as: %s", source, format)
}
// Device is not formatted, so we can safely create a new LUKS2 partition
if err := device.Format(
cryptsetup.LUKS2{
SectorSize: 4096,
Integrity: integrityType,
PBKDFType: &cryptsetup.PbkdfType{
// Use low memory recommendation from https://datatracker.ietf.org/doc/html/rfc9106#section-7
Type: "argon2id",
TimeMs: 2000,
Iterations: 3,
ParallelThreads: 4,
MaxMemoryKb: 65536, // ~64MiB
},
},
cryptsetup.GenericParams{
Cipher: "aes",
CipherMode: "xts-plain64",
VolumeKeySize: keySize,
}); err != nil {
return "", fmt.Errorf("formatting device %q: %w", source, err)
}
uuid := device.GetUUID()
passphrase, err = getKey(ctx, uuid, crypto.StateDiskKeyLength)
if err != nil {
return "", err
}
if len(passphrase) != crypto.StateDiskKeyLength {
return "", fmt.Errorf("expected key length to be [%d] but got [%d]", crypto.StateDiskKeyLength, len(passphrase))
}
// Add a new keyslot using the internal volume key
if err := device.KeyslotAddByVolumeKey(0, "", string(passphrase)); err != nil {
return "", fmt.Errorf("adding keyslot: %w", err)
}
if integrity {
if err := performWipe(device, volumeID); err != nil {
return "", fmt.Errorf("wiping device: %w", err)
}
}
} else {
uuid := device.GetUUID()
passphrase, err = getKey(ctx, uuid, crypto.StateDiskKeyLength)
if err != nil {
return "", err
}
if len(passphrase) != crypto.StateDiskKeyLength {
return "", fmt.Errorf("expected key length to be [%d] but got [%d]", crypto.StateDiskKeyLength, len(passphrase))
}
}
if err := device.ActivateByPassphrase(volumeID, 0, string(passphrase), ccryptsetup.ReadWriteQueueBypass); err != nil {
return "", fmt.Errorf("trying to activate dm-crypt volume: %w", err)
}
return cryptPrefix + volumeID, nil
}
// performWipe handles setting up parameters and clearing the device for dm-integrity.
func performWipe(device DeviceMapper, volumeID string) error {
tmpDevice := "temporary-cryptsetup-" + volumeID
// Active as temporary device
if err := device.ActivateByVolumeKey(tmpDevice, "", 0, (cryptsetup.CRYPT_ACTIVATE_PRIVATE | cryptsetup.CRYPT_ACTIVATE_NO_JOURNAL)); err != nil {
return fmt.Errorf("trying to activate temporary dm-crypt volume: %w", err)
}
// No terminal available, limit callbacks to once every 30 seconds to not fill up logs with large amount of progress updates
ticker := time.NewTicker(30 * time.Second)
firstReq := make(chan struct{}, 1)
firstReq <- struct{}{}
defer ticker.Stop()
logProgress := func(size, offset uint64) {
prog := (float64(offset) / float64(size)) * 100
fmt.Printf("Wipe in progress: %.2f%%\n", prog)
}
progressCallback := func(size, offset uint64) int {
select {
case <-firstReq:
logProgress(size, offset)
case <-ticker.C:
logProgress(size, offset)
default:
}
return 0
}
// Wipe the device using the same options as used in cryptsetup: https://gitlab.com/cryptsetup/cryptsetup/-/blob/v2.4.3/src/cryptsetup.c#L1345
if err := device.Wipe(cryptPrefix+tmpDevice, cryptsetup.CRYPT_WIPE_ZERO, 0, 0, 1024*1024, 0, progressCallback); err != nil {
return err
}
// Deactivate the temporary device
if err := device.Deactivate(tmpDevice); err != nil {
return fmt.Errorf("deactivating temporary volume: %w", err)
}
return nil
}
func resizeCryptDevice(ctx context.Context, device DeviceMapper, name string,
getKey func(ctx context.Context, keyID string, keySize int) ([]byte, error),
) error {
packageLock.Lock()
defer packageLock.Unlock()
if err := device.InitByName(name); err != nil {
return fmt.Errorf("initializing device: %w", err)
}
defer device.Free()
if err := device.Load(cryptsetup.LUKS2{}); err != nil {
return fmt.Errorf("loading device: %w", err)
}
passphrase, err := getKey(ctx, device.GetUUID(), crypto.StateDiskKeyLength)
if err != nil {
return fmt.Errorf("getting key: %w", err)
}
if err := device.ActivateByPassphrase("", 0, string(passphrase), cryptsetup.CRYPT_ACTIVATE_KEYRING_KEY|ccryptsetup.ReadWriteQueueBypass); err != nil {
return fmt.Errorf("activating keyring for crypt device %q with passphrase: %w", name, err)
}
if err := device.Resize(name, 0); err != nil {
return fmt.Errorf("resizing device: %w", err)
}
return nil
}
func getDevicePath(device DeviceMapper, name string) (string, error) {
packageLock.Lock()
defer packageLock.Unlock()
if err := device.InitByName(name); err != nil {
return "", fmt.Errorf("initializing device: %w", err)
}
defer device.Free()
deviceName := device.GetDeviceName()
if deviceName == "" {
return "", errors.New("unable to determine device name")
}
return deviceName, nil
}
// IsIntegrityFS checks if the fstype string contains an integrity suffix.
// If yes, returns the trimmed fstype and true, fstype and false otherwise.
func IsIntegrityFS(fstype string) (string, bool) {
if strings.HasSuffix(fstype, integrityFSSuffix) {
return strings.TrimSuffix(fstype, integrityFSSuffix), true
}
return fstype, false
}