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efs: add encrypted file system store
Add a keystore implementation, that wraps a file system store, but encrypts the files. Signed-off-by: Sascha Wolke <[email protected]>
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| // Copyright 2024 - MinIO, Inc. All rights reserved. | ||
| // Use of this source code is governed by the AGPLv3 | ||
| // license that can be found in the LICENSE file. | ||
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| // Package efs implements a key-value store that | ||
| // stores keys as file names and values as encrypted | ||
| // file content. | ||
| // | ||
| // It wraps a fs store and in addition, encrypt the keys. | ||
| package efs | ||
|
|
||
| import ( | ||
| "context" | ||
| "errors" | ||
| "fmt" | ||
| "io" | ||
| "os" | ||
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| "aead.dev/mem" | ||
| "github.com/minio/kes" | ||
| "github.com/minio/kes/internal/crypto" | ||
| "github.com/minio/kes/internal/fips" | ||
| "github.com/minio/kes/internal/keystore/fs" | ||
| ) | ||
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| // NewStore returns a new Store that reads | ||
| // from and writes to the given directory, | ||
| // using encryption. | ||
| // | ||
| // If the directory or any parent directory | ||
| // does not exist, NewStore creates them all. | ||
| // | ||
| // It returns an error if dir exists but is | ||
| // not a directory. | ||
| func NewStore(keyPath string, keyCipher string, dir string) (*Store, error) { | ||
| fsStore, err := fs.NewStore(dir) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
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| key, err := loadMasterKey(keyPath, keyCipher) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
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| return &Store{key: key, fsStore: fsStore}, nil | ||
| } | ||
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| // loadMasterKey reads a secret key from a | ||
| // given path. | ||
| // | ||
| // If the key file does not exist, or contains | ||
| // an unexpected amount of bytes, it returns an error. | ||
| func loadMasterKey(keyPath string, keyCipher string) (crypto.SecretKey, error) { | ||
| file, err := os.Open(keyPath) | ||
| if errors.Is(err, os.ErrNotExist) { | ||
| return crypto.SecretKey{}, fmt.Errorf("master key not found: '%s'", keyPath) | ||
| } | ||
| if err != nil { | ||
| return crypto.SecretKey{}, err | ||
| } | ||
| defer file.Close() | ||
|
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| const MaxSize = crypto.SecretKeySize + 1 | ||
| value, err := io.ReadAll(mem.LimitReader(file, MaxSize)) | ||
| if err != nil { | ||
| return crypto.SecretKey{}, err | ||
| } | ||
| if err = file.Close(); err != nil { | ||
| return crypto.SecretKey{}, err | ||
| } | ||
| if len(value) != crypto.SecretKeySize { | ||
| return crypto.SecretKey{}, fmt.Errorf("invalid master key size for '%s'", keyCipher) | ||
| } | ||
|
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| cipher, err := crypto.ParseSecretKeyType(keyCipher) | ||
| if err != nil { | ||
| return crypto.SecretKey{}, err | ||
| } | ||
| if cipher == crypto.ChaCha20 && fips.Enabled { | ||
| return crypto.SecretKey{}, fmt.Errorf("master key algorithm '%s' not supported by FIPS 140-2", keyCipher) | ||
| } | ||
|
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| return crypto.NewSecretKey(cipher, value) | ||
| } | ||
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| // Store is a connection to a directory on | ||
| // the filesystem using a secret key to encrypt the files. | ||
| // | ||
| // It implements the kms.Store interface and | ||
| // acts as KMS abstraction over a filesystem. | ||
| type Store struct { | ||
| key crypto.SecretKey | ||
| fsStore *fs.Store | ||
| } | ||
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| func (s *Store) String() string { return "Encrypted Filesystem: " + s.fsStore.Dir() } | ||
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| // Status returns the current state of the Conn. | ||
| // | ||
| // In particular, it reports whether the underlying | ||
| // filesystem is accessible. | ||
| func (s *Store) Status(ctx context.Context) (kes.KeyStoreState, error) { | ||
| return s.fsStore.Status(ctx) | ||
| } | ||
|
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| // Create creates a new file with the given name inside | ||
| // the Conn directory if and only if no such file exists. | ||
| // | ||
| // It returns kes.ErrKeyExists if such a file already exists. | ||
| func (s *Store) Create(ctx context.Context, name string, value []byte) error { | ||
| context := fmt.Sprintf("name=%s", name) | ||
| encryptedValue, err := s.key.Encrypt(value, []byte(context)) | ||
| if err != nil { | ||
| return err | ||
| } | ||
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| return s.fsStore.Create(ctx, name, encryptedValue) | ||
| } | ||
|
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| // Get reads the content of the named file within the Conn | ||
| // directory. It returns kes.ErrKeyNotFound if no such file | ||
| // exists. | ||
| func (s *Store) Get(ctx context.Context, name string) ([]byte, error) { | ||
| encryptedValue, err := s.fsStore.Get(ctx, name) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
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| context := fmt.Sprintf("name=%s", name) | ||
| value, err := s.key.Decrypt(encryptedValue, []byte(context)) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
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| return value, nil | ||
| } | ||
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| // Delete deletes the named file within the Conn directory if | ||
| // and only if it exists. It returns kes.ErrKeyNotFound if | ||
| // no such file exists. | ||
| func (s *Store) Delete(ctx context.Context, name string) error { | ||
| return s.fsStore.Delete(ctx, name) | ||
| } | ||
|
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| // List returns a new Iterator over the names of | ||
| // all stored keys. | ||
| // List returns the first n key names, that start with the given | ||
| // prefix, and the next prefix from which the listing should | ||
| // continue. | ||
| // | ||
| // It returns all keys with the prefix if n < 0 and less than n | ||
| // names if n is greater than the number of keys with the prefix. | ||
| // | ||
| // An empty prefix matches any key name. At the end of the listing | ||
| // or when there are no (more) keys starting with the prefix, the | ||
| // returned prefix is empty | ||
| func (s *Store) List(ctx context.Context, prefix string, n int) ([]string, string, error) { | ||
| return s.fsStore.List(ctx, prefix, n) | ||
| } | ||
|
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| // Close closes the Store. | ||
| func (s *Store) Close() error { | ||
| return s.fsStore.Close() | ||
| } |
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