Initial commit: DSH Web Manager

2026-10-13 09:34:47 +08:00
commit 85332bbc56
135 changed files with 19712 additions and 0 deletions
@@ -0,0 +1,102 @@
+package backup
+
+import (
+	"bytes"
+	"crypto/rand"
+	"errors"
+	"os"
+	"path/filepath"
+	"syscall"
+
+	"golang.org/x/crypto/argon2"
+)
+
+const passwordMagic = "DSHPASS\x01"
+const MaxEncryptedBytes int64 = int64(maxArchiveBytes + len(passwordMagic) + 16)
+
+// The format fixes KDF costs; untrusted archives cannot request arbitrary memory.
+func passwordKey(password string, salt []byte) ([]byte, error) {
+	if len(password) == 0 || len(password) > 1024 {
+		return nil, errors.New("backup password required (maximum 1024 bytes)")
+	}
+	return argon2.IDKey([]byte(password), salt, 3, 64*1024, 2, 32), nil
+}
+
+func CreateWithPassword(home, destination, password string, metadata Metadata) error {
+	salt := make([]byte, 16)
+	if _, err := rand.Read(salt); err != nil {
+		return err
+	}
+	key, err := passwordKey(password, salt)
+	if err != nil {
+		return err
+	}
+	defer clear(key)
+	dir, err := os.MkdirTemp(filepath.Dir(destination), ".password-backup-")
+	if err != nil {
+		return err
+	}
+	defer os.RemoveAll(dir)
+	inner := filepath.Join(dir, "archive")
+	if err = CreateWithMetadata(home, inner, key, metadata); err != nil {
+		return err
+	}
+	data, err := os.ReadFile(inner)
+	if err != nil {
+		return err
+	}
+	data = append(append([]byte(passwordMagic), salt...), data...)
+	root, err := os.OpenRoot(filepath.Dir(destination))
+	if err != nil {
+		return err
+	}
+	defer root.Close()
+	return replace(root, filepath.Base(destination), data)
+}
+
+// Prepare authenticates and validates into a private staging home before the caller
+// stops a container or snapshots its live home. Only ciphertext is retained.
+func Prepare(archive, password string, legacyKey []byte) (restore func(string) error, cleanup func(), err error) {
+	f, err := os.OpenFile(archive, os.O_RDONLY|syscall.O_NOFOLLOW|syscall.O_NONBLOCK, 0)
+	if err != nil {
+		return nil, nil, err
+	}
+	data, err := readBounded(f, MaxEncryptedBytes)
+	f.Close()
+	if err != nil {
+		return nil, nil, err
+	}
+	key := append([]byte(nil), legacyKey...)
+	if bytes.HasPrefix(data, []byte(passwordMagic)) {
+		if len(data) < len(passwordMagic)+16 {
+			return nil, nil, errors.New("truncated backup")
+		}
+		key, err = passwordKey(password, data[len(passwordMagic):len(passwordMagic)+16])
+		if err != nil {
+			return nil, nil, err
+		}
+		data = data[len(passwordMagic)+16:]
+	}
+	dir, err := os.MkdirTemp("", "dsh-backup-validate-")
+	if err != nil {
+		clear(key)
+		return nil, nil, err
+	}
+	cleanup = func() { clear(key); os.RemoveAll(dir) }
+	inner := filepath.Join(dir, "archive")
+	if err = os.WriteFile(inner, data, 0600); err == nil {
+		err = os.Mkdir(filepath.Join(dir, "home"), 0700)
+	}
+	if err == nil {
+		err = Restore(inner, filepath.Join(dir, "home"), key)
+	}
+	if err != nil {
+		cleanup()
+		return nil, nil, err
+	}
+	if err = os.RemoveAll(filepath.Join(dir, "home")); err != nil {
+		cleanup()
+		return nil, nil, err
+	}
+	return func(home string) error { return Restore(inner, home, key) }, cleanup, nil
+}