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store.go
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store.go
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package macaroons
import (
"bytes"
"context"
"crypto/rand"
"fmt"
"io"
"sync"
"github.com/btcsuite/btcwallet/snacl"
"github.com/btcsuite/btcwallet/walletdb"
"github.com/lightningnetwork/lnd/kvdb"
)
const (
// RootKeyLen is the length of a root key.
RootKeyLen = 32
)
var (
// rootKeyBucketName is the name of the root key store bucket.
rootKeyBucketName = []byte("macrootkeys")
// DefaultRootKeyID is the ID of the default root key. The first is
// just 0, to emulate the memory storage that comes with bakery.
DefaultRootKeyID = []byte("0")
// encryptionKeyID is the name of the database key that stores the
// encryption key, encrypted with a salted + hashed password. The
// format is 32 bytes of salt, and the rest is encrypted key.
encryptionKeyID = []byte("enckey")
// ErrAlreadyUnlocked specifies that the store has already been
// unlocked.
ErrAlreadyUnlocked = fmt.Errorf("macaroon store already unlocked")
// ErrStoreLocked specifies that the store needs to be unlocked with
// a password.
ErrStoreLocked = fmt.Errorf("macaroon store is locked")
// ErrPasswordRequired specifies that a nil password has been passed.
ErrPasswordRequired = fmt.Errorf("a non-nil password is required")
// ErrKeyValueForbidden is used when the root key ID uses encryptedKeyID as
// its value.
ErrKeyValueForbidden = fmt.Errorf("root key ID value is not allowed")
// ErrRootKeyBucketNotFound specifies that there is no macaroon root key
// bucket yet which can/should only happen if the store has been
// corrupted or was initialized incorrectly.
ErrRootKeyBucketNotFound = fmt.Errorf("root key bucket not found")
// ErrEncKeyNotFound specifies that there was no encryption key found
// even if one was expected to be generated.
ErrEncKeyNotFound = fmt.Errorf("macaroon encryption key not found")
// ErrDefaultRootKeyNotFound is returned when the default root key is
// not found in the DB when it is expected to be.
ErrDefaultRootKeyNotFound = fmt.Errorf("default root key not found")
)
// RootKeyStorage implements the bakery.RootKeyStorage interface.
type RootKeyStorage struct {
kvdb.Backend
encKeyMtx sync.RWMutex
encKey *snacl.SecretKey
}
// NewRootKeyStorage creates a RootKeyStorage instance.
func NewRootKeyStorage(db kvdb.Backend) (*RootKeyStorage, error) {
// If the store's bucket doesn't exist, create it.
err := kvdb.Update(db, func(tx kvdb.RwTx) error {
_, err := tx.CreateTopLevelBucket(rootKeyBucketName)
return err
}, func() {})
if err != nil {
return nil, err
}
// Return the DB wrapped in a RootKeyStorage object.
return &RootKeyStorage{
Backend: db,
encKey: nil,
}, nil
}
// CreateUnlock sets an encryption key if one is not already set, otherwise it
// checks if the password is correct for the stored encryption key.
func (r *RootKeyStorage) CreateUnlock(password *[]byte) error {
r.encKeyMtx.Lock()
defer r.encKeyMtx.Unlock()
// Check if we've already unlocked the store; return an error if so.
if r.encKey != nil {
return ErrAlreadyUnlocked
}
// Check if a nil password has been passed; return an error if so.
if password == nil {
return ErrPasswordRequired
}
return kvdb.Update(r.Backend, func(tx kvdb.RwTx) error {
bucket := tx.ReadWriteBucket(rootKeyBucketName)
if bucket == nil {
return ErrRootKeyBucketNotFound
}
dbKey := bucket.Get(encryptionKeyID)
if len(dbKey) > 0 {
// We've already stored a key, so try to unlock with
// the password.
encKey := &snacl.SecretKey{}
err := encKey.Unmarshal(dbKey)
if err != nil {
return err
}
err = encKey.DeriveKey(password)
if err != nil {
return err
}
r.encKey = encKey
return nil
}
// We haven't yet stored a key, so create a new one.
encKey, err := snacl.NewSecretKey(
password, scryptN, scryptR, scryptP,
)
if err != nil {
return err
}
err = bucket.Put(encryptionKeyID, encKey.Marshal())
if err != nil {
return err
}
r.encKey = encKey
return nil
}, func() {})
}
// ChangePassword decrypts all the macaroon root keys with the old password and
// then encrypts them again with the new password.
func (r *RootKeyStorage) ChangePassword(oldPw, newPw []byte) error {
// We need the store to already be unlocked. With this we can make sure
// that there already is a key in the DB.
if r.encKey == nil {
return ErrStoreLocked
}
// Check if a nil password has been passed; return an error if so.
if oldPw == nil || newPw == nil {
return ErrPasswordRequired
}
return kvdb.Update(r.Backend, func(tx kvdb.RwTx) error {
bucket := tx.ReadWriteBucket(rootKeyBucketName)
if bucket == nil {
return ErrRootKeyBucketNotFound
}
// The encryption key must be present, otherwise we are in the
// wrong state to change the password.
encKeyDB := bucket.Get(encryptionKeyID)
if len(encKeyDB) == 0 {
return ErrEncKeyNotFound
}
// Unmarshal parameters for old encryption key and derive the
// old key with them.
encKeyOld := &snacl.SecretKey{}
err := encKeyOld.Unmarshal(encKeyDB)
if err != nil {
return err
}
err = encKeyOld.DeriveKey(&oldPw)
if err != nil {
return err
}
// Create a new encryption key from the new password.
encKeyNew, err := snacl.NewSecretKey(
&newPw, scryptN, scryptR, scryptP,
)
if err != nil {
return err
}
// foundDefaultRootKey is used to keep track of if we have
// found and re-encrypted the default root key so that we can
// return an error if it is not found.
var foundDefaultRootKey bool
err = bucket.ForEach(func(k, v []byte) error {
// Skip the key if it is the encryption key ID since
// we do not want to re-encrypt this.
if bytes.Equal(k, encryptionKeyID) {
return nil
}
if bytes.Equal(k, DefaultRootKeyID) {
foundDefaultRootKey = true
}
// Now try to decrypt the root key with the old
// encryption key, encrypt it with the new one and then
// store it in the DB.
decryptedKey, err := encKeyOld.Decrypt(v)
if err != nil {
return err
}
encryptedKey, err := encKeyNew.Encrypt(decryptedKey)
if err != nil {
return err
}
return bucket.Put(k, encryptedKey)
})
if err != nil {
return err
}
if !foundDefaultRootKey {
return ErrDefaultRootKeyNotFound
}
// Finally, store the new encryption key parameters in the DB
// as well.
err = bucket.Put(encryptionKeyID, encKeyNew.Marshal())
if err != nil {
return err
}
r.encKey = encKeyNew
return nil
}, func() {})
}
// Get implements the Get method for the bakery.RootKeyStorage interface.
func (r *RootKeyStorage) Get(_ context.Context, id []byte) ([]byte, error) {
r.encKeyMtx.RLock()
defer r.encKeyMtx.RUnlock()
if r.encKey == nil {
return nil, ErrStoreLocked
}
var rootKey []byte
err := kvdb.View(r.Backend, func(tx kvdb.RTx) error {
bucket := tx.ReadBucket(rootKeyBucketName)
if bucket == nil {
return ErrRootKeyBucketNotFound
}
dbKey := bucket.Get(id)
if len(dbKey) == 0 {
return fmt.Errorf("root key with id %s doesn't exist",
string(id))
}
decKey, err := r.encKey.Decrypt(dbKey)
if err != nil {
return err
}
rootKey = make([]byte, len(decKey))
copy(rootKey[:], decKey)
return nil
}, func() {
rootKey = nil
})
if err != nil {
return nil, err
}
return rootKey, nil
}
// RootKey implements the RootKey method for the bakery.RootKeyStorage
// interface.
func (r *RootKeyStorage) RootKey(ctx context.Context) ([]byte, []byte, error) {
r.encKeyMtx.RLock()
defer r.encKeyMtx.RUnlock()
if r.encKey == nil {
return nil, nil, ErrStoreLocked
}
var rootKey []byte
// Read the root key ID from the context. If no key is specified in the
// context, an error will be returned.
id, err := RootKeyIDFromContext(ctx)
if err != nil {
return nil, nil, err
}
if bytes.Equal(id, encryptionKeyID) {
return nil, nil, ErrKeyValueForbidden
}
err = kvdb.Update(r.Backend, func(tx kvdb.RwTx) error {
bucket := tx.ReadWriteBucket(rootKeyBucketName)
if bucket == nil {
return ErrRootKeyBucketNotFound
}
dbKey := bucket.Get(id)
// If there's a root key stored in the bucket, decrypt it and
// return it.
if len(dbKey) != 0 {
decKey, err := r.encKey.Decrypt(dbKey)
if err != nil {
return err
}
rootKey = make([]byte, len(decKey))
copy(rootKey[:], decKey[:])
return nil
}
// Otherwise, create a new root key, encrypt it,
// and store it in the bucket.
newKey, err := generateAndStoreNewRootKey(bucket, id, r.encKey)
rootKey = newKey
return err
}, func() {
rootKey = nil
})
if err != nil {
return nil, nil, err
}
return rootKey, id, nil
}
// GenerateNewRootKey generates a new macaroon root key, replacing the previous
// root key if it existed.
func (r *RootKeyStorage) GenerateNewRootKey() error {
// We need the store to already be unlocked. With this we can make sure
// that there already is a key in the DB that can be replaced.
if r.encKey == nil {
return ErrStoreLocked
}
return kvdb.Update(r.Backend, func(tx kvdb.RwTx) error {
bucket := tx.ReadWriteBucket(rootKeyBucketName)
if bucket == nil {
return ErrRootKeyBucketNotFound
}
// The default root key should be created even if it does not
// yet exist, so we do this separately from the rest of the
// root keys.
_, err := generateAndStoreNewRootKey(
bucket, DefaultRootKeyID, r.encKey,
)
if err != nil {
return err
}
// Now iterate over all the other root keys that may exist
// and re-generate each of them.
return bucket.ForEach(func(k, v []byte) error {
if bytes.Equal(k, encryptionKeyID) {
return nil
}
if bytes.Equal(k, DefaultRootKeyID) {
return nil
}
_, err := generateAndStoreNewRootKey(
bucket, k, r.encKey,
)
return err
})
}, func() {})
}
// SetRootKey sets the default macaroon root key, replacing the previous root
// key if it existed.
func (r *RootKeyStorage) SetRootKey(rootKey []byte) error {
if r.encKey == nil {
return ErrStoreLocked
}
if len(rootKey) != RootKeyLen {
return fmt.Errorf("root key must be %v bytes",
RootKeyLen)
}
encryptedKey, err := r.encKey.Encrypt(rootKey)
if err != nil {
return err
}
return kvdb.Update(r.Backend, func(tx kvdb.RwTx) error {
bucket := tx.ReadWriteBucket(rootKeyBucketName)
if bucket == nil {
return ErrRootKeyBucketNotFound
}
return bucket.Put(DefaultRootKeyID, encryptedKey)
}, func() {})
}
// Close closes the underlying database and zeroes the encryption key stored
// in memory.
func (r *RootKeyStorage) Close() error {
r.encKeyMtx.Lock()
defer r.encKeyMtx.Unlock()
if r.encKey != nil {
r.encKey.Zero()
r.encKey = nil
}
// Since we're not responsible for _creating_ the connection to our DB
// backend, we also shouldn't close it. This should be handled
// externally as to not interfere with remote DB connections in case we
// need to open/close the store twice as happens in the password change
// case.
return nil
}
// generateAndStoreNewRootKey creates a new random RootKeyLen-byte root key,
// encrypts it with the given encryption key and stores it in the bucket.
// Any previously set key will be overwritten.
func generateAndStoreNewRootKey(bucket walletdb.ReadWriteBucket, id []byte,
key *snacl.SecretKey) ([]byte, error) {
rootKey := make([]byte, RootKeyLen)
if _, err := io.ReadFull(rand.Reader, rootKey); err != nil {
return nil, err
}
encryptedKey, err := key.Encrypt(rootKey)
if err != nil {
return nil, err
}
return rootKey, bucket.Put(id, encryptedKey)
}
// ListMacaroonIDs returns all the root key ID values except the value of
// encryptedKeyID.
func (r *RootKeyStorage) ListMacaroonIDs(_ context.Context) ([][]byte, error) {
r.encKeyMtx.RLock()
defer r.encKeyMtx.RUnlock()
// Check it's unlocked.
if r.encKey == nil {
return nil, ErrStoreLocked
}
var rootKeySlice [][]byte
// Read all the items in the bucket and append the keys, which are the
// root key IDs we want.
err := kvdb.View(r.Backend, func(tx kvdb.RTx) error {
// appendRootKey is a function closure that appends root key ID
// to rootKeySlice.
appendRootKey := func(k, _ []byte) error {
// Only append when the key value is not encryptedKeyID.
if !bytes.Equal(k, encryptionKeyID) {
rootKeySlice = append(rootKeySlice, k)
}
return nil
}
return tx.ReadBucket(rootKeyBucketName).ForEach(appendRootKey)
}, func() {
rootKeySlice = nil
})
if err != nil {
return nil, err
}
return rootKeySlice, nil
}
// DeleteMacaroonID removes one specific root key ID. If the root key ID is
// found and deleted, it will be returned.
func (r *RootKeyStorage) DeleteMacaroonID(
_ context.Context, rootKeyID []byte) ([]byte, error) {
r.encKeyMtx.RLock()
defer r.encKeyMtx.RUnlock()
// Check it's unlocked.
if r.encKey == nil {
return nil, ErrStoreLocked
}
// Check the rootKeyID is not empty.
if len(rootKeyID) == 0 {
return nil, ErrMissingRootKeyID
}
// Deleting encryptedKeyID or DefaultRootKeyID is not allowed.
if bytes.Equal(rootKeyID, encryptionKeyID) ||
bytes.Equal(rootKeyID, DefaultRootKeyID) {
return nil, ErrDeletionForbidden
}
var rootKeyIDDeleted []byte
err := kvdb.Update(r.Backend, func(tx kvdb.RwTx) error {
bucket := tx.ReadWriteBucket(rootKeyBucketName)
// Check the key can be found. If not, return nil.
if bucket.Get(rootKeyID) == nil {
return nil
}
// Once the key is found, we do the deletion.
if err := bucket.Delete(rootKeyID); err != nil {
return err
}
rootKeyIDDeleted = rootKeyID
return nil
}, func() {
rootKeyIDDeleted = nil
})
if err != nil {
return nil, err
}
return rootKeyIDDeleted, nil
}