A secret mv between vaults unlocks both vaults before taking the lock (closes #189)

A move between two vaults unlocked them while holding the state directory
lock, and unlocking can ask for a passphrase, so every other changing
command waited at that prompt. moveSecretCrossVault now checks the move,
unlocks both vaults, and only then takes the lock. Under the lock,
copySecretAndRemoveSource checks again that the source and the destination
vault still exist, then copies. A move within a vault takes the lock in
moveSecretWithinVault, so MoveSecret takes none itself.

The two tests of a source that cannot be removed now call
copySecretAndRemoveSource, since the lock refuses their wrapped
filesystems.

Model: opus-5-5

internal/cli/move_cross_vault_test.go

@@ -4,12 +4,15 @@ package cli
 import (
 	"errors"
 	"path/filepath"
+	"sync"
 	"testing"
+	"time"
 
 	"github.com/awnumar/memguard"
 	"github.com/spf13/afero"
 	"github.com/spf13/cobra"
 	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/secret/internal/secret"
 	"sneak.berlin/go/secret/internal/vault"
 )
 
@@ -92,7 +95,8 @@ func requireValue(t *testing.T, fs afero.Fs, vaultName, secretName string) {
 // vaults whose source could not be removed reported the secret moved and
 // succeeded. It must fail, and the copy and the source must both be there.
 // The state directory lock refuses the wrapped filesystem, so the test
-// calls moveSecret, which MoveSecret runs once it holds the lock.
+// calls copySecretAndRemoveSource, which a move between vaults runs once it
+// holds the lock.
 func TestCrossVaultMoveFailsWhenSourceRemains(t *testing.T) {
 	t.Parallel()
 
@@ -103,9 +107,12 @@ func TestCrossVaultMoveFailsWhenSourceRemains(t *testing.T) {
 		Fs:   base,
 		path: testStateDir + "/vaults.d/default/secrets.d/x",
 	}, testStateDir)
-	instance.Mnemonic = testMnemonicBuffer(t)
 
-	err := instance.moveSecret(&cobra.Command{}, "default:x", "work:y", false)
+	source := vault.NewVault(instance.fs, testStateDir, "default")
+	source.Mnemonic = testMnemonicBuffer(t)
+
+	err := instance.copySecretAndRemoveSource(&cobra.Command{}, source, "x",
+		vault.NewVault(instance.fs, testStateDir, "work"), "y", false)
 	require.ErrorIs(t, err, errPermissionDenied)
 	require.ErrorContains(t, err, "secret 'default:x' is copied with all "+
 		"1 version(s) to 'work:y', but the source remains")
@@ -128,9 +135,12 @@ func TestCrossVaultMoveFailsWhenOldFilesRemain(t *testing.T) {
 	fs := &removeAllFailFs{Fs: base, dir: sourceVaultDir}
 
 	instance := NewCLIInstanceWithStateDir(fs, testStateDir)
-	instance.Mnemonic = testMnemonicBuffer(t)
 
-	err := instance.moveSecret(&cobra.Command{}, "default:x", "work:y", false)
+	source := vault.NewVault(fs, testStateDir, "default")
+	source.Mnemonic = testMnemonicBuffer(t)
+
+	err := instance.copySecretAndRemoveSource(&cobra.Command{}, source, "x",
+		vault.NewVault(fs, testStateDir, "work"), "y", false)
 	require.ErrorIs(t, err, errPermissionDenied)
 	require.ErrorContains(t, err, "secret 'default:x' is moved with all "+
 		"1 version(s) to 'work:y', but its old files could not all be deleted")
@@ -150,3 +160,138 @@ func TestCrossVaultMoveFailsWhenOldFilesRemain(t *testing.T) {
 
 	requireValue(t, base, "work", "y")
 }
+
+// TestCrossVaultMoveUnlocksBeforeLocking is a regression test for
+// https://git.eeqj.de/sneak/secret/issues/189: a move between two vaults
+// unlocked them while holding the state directory lock, and unlocking a
+// vault can ask for its passphrase, so every other command that changes
+// anything waited while the user answered. Here each vault has a passphrase
+// unlocker whose passphrase is the vault's name, and the move is given the
+// passphrase of only one of them. Run while the test holds the lock, it
+// must fail to unlock the other vault without waiting for the lock.
+//
+//nolint:paralleltest // times commands against the in-memory lock all tests share
+func TestCrossVaultMoveUnlocksBeforeLocking(t *testing.T) {
+	fs := afero.NewMemMapFs()
+	createCrossVaults(t, fs)
+
+	vaults, err := vault.ListVaults(fs, testStateDir)
+	require.NoError(t, err)
+
+	for _, name := range vaults {
+		vlt := vault.NewVault(fs, testStateDir, name)
+		vlt.Mnemonic = testMnemonicBuffer(t)
+
+		passphrase := memguard.NewBufferFromBytes([]byte(name))
+		_, err = vlt.CreatePassphraseUnlocker(passphrase)
+		passphrase.Destroy()
+		require.NoError(t, err)
+	}
+
+	// The move is from "default" to "work"
+	for _, tc := range []struct {
+		// failing is the vault that the move cannot unlock, given the
+		// passphrase of the vault named given
+		failing, given string
+	}{
+		{"source", "work"},
+		{"destination", "default"},
+	} {
+		t.Run(tc.failing, func(t *testing.T) {
+			passphrase := memguard.NewBufferFromBytes([]byte(tc.given))
+			defer passphrase.Destroy()
+
+			instance := NewCLIInstanceWithStateDir(fs, testStateDir)
+			instance.UnlockPassphrase = passphrase
+
+			release, err := vault.LockStateDir(fs, testStateDir)
+			require.NoError(t, err)
+			// Also frees a waiting move if the test fails, so that it
+			// releases the lock the other tests use
+			defer release()
+
+			done := make(chan error, 1)
+
+			go func() {
+				done <- instance.MoveSecret(&cobra.Command{},
+					"default:x", "work:y", false)
+			}()
+
+			select {
+			case err := <-done:
+				require.ErrorIs(t, err, secret.ErrWrongPassphrase)
+				require.ErrorContains(t, err,
+					"failed to unlock "+tc.failing+" vault")
+			case <-time.After(lockWait):
+				t.Fatal("waited for the lock before unlocking the " +
+					tc.failing + " vault")
+			}
+		})
+	}
+}
+
+// TestCrossVaultMoveChecksAgainOnceLocked starts a move between two vaults,
+// given the mnemonic, while the test holds the state directory lock. Once
+// the move waits for the lock, the test removes what another command could
+// have removed in the meantime, then releases the lock. The move must fail
+// with the error that says what is missing.
+//
+//nolint:paralleltest // waitingForLock sees any test's command waiting for the lock
+func TestCrossVaultMoveChecksAgainOnceLocked(t *testing.T) {
+	for _, tc := range []struct {
+		name string
+		// removed is the directory, under the state directory, that the
+		// test removes
+		removed string
+		want    error
+	}{
+		{"source", "/vaults.d/default/secrets.d/x", vault.ErrSecretNotFound},
+		{"destination vault", "/vaults.d/work", vault.ErrVaultNotFound},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			fs := afero.NewMemMapFs()
+			createCrossVaults(t, fs)
+
+			release, err := vault.LockStateDir(fs, testStateDir)
+			require.NoError(t, err)
+
+			// Released at most once, and also if the test fails while
+			// holding it, so that later tests can take it
+			release = sync.OnceFunc(release)
+			defer release()
+
+			instance := NewCLIInstanceWithStateDir(fs, testStateDir)
+			instance.Mnemonic = testMnemonicBuffer(t)
+
+			done := make(chan error, 1)
+
+			go func() {
+				done <- instance.MoveSecret(&cobra.Command{},
+					"default:x", "work:y", false)
+			}()
+
+			timeout := time.After(lockWait)
+
+			for !waitingForLock() {
+				select {
+				case err := <-done:
+					t.Fatalf("finished while the lock was held, with error %v",
+						err)
+				case <-timeout:
+					t.Fatal("never waited for the lock")
+				case <-time.After(time.Millisecond):
+				}
+			}
+
+			require.NoError(t, fs.RemoveAll(testStateDir+tc.removed))
+			release()
+
+			select {
+			case err := <-done:
+				require.ErrorIs(t, err, tc.want)
+			case <-time.After(lockWait):
+				t.Fatal("did not finish once the lock was released")
+			}
+		})
+	}
+}

internal/cli/secrets.go

@@ -875,24 +875,12 @@ func (cli *Instance) findSecretToRemove(
 	}, nil
 }
 
-// MoveSecret moves or renames a secret (within or across vaults), holding
-// the state directory lock.
+// MoveSecret moves or renames a secret (within or across vaults). It
+// leaves taking the state directory lock to moveSecretWithinVault and
+// moveSecretCrossVault, since a move between vaults unlocks both vaults
+// before it takes the lock.
 func (cli *Instance) MoveSecret(
 	cmd *cobra.Command, source, dest string, force bool,
-) error {
-	release, err := vault.LockStateDir(cli.fs, cli.stateDir)
-	if err != nil {
-		return err
-	}
-	defer release()
-
-	return cli.moveSecret(cmd, source, dest, force)
-}
-
-// moveSecret does the work of MoveSecret. The caller holds the state
-// directory lock.
-func (cli *Instance) moveSecret(
-	cmd *cobra.Command, source, dest string, force bool,
 ) error {
 	// Parse source and destination
 	srcVaultName, srcSecretName, srcQualified := ParseVaultSecretRef(source)
@@ -992,8 +980,9 @@ func (cli *Instance) existingVault(name string) (*vault.Vault, error) {
 	return vault.NewVault(cli.fs, cli.stateDir, name), nil
 }
 
-// moveSecretWithinVault renames a secret within the vault vlt. Its caller,
-// MoveSecret, has already checked both secret names.
+// moveSecretWithinVault renames a secret within the vault vlt, holding the
+// state directory lock. Its caller, MoveSecret, has already checked both
+// secret names.
 func (cli *Instance) moveSecretWithinVault(
 	cmd *cobra.Command, vlt *vault.Vault, source, dest string, force bool,
 ) error {
@@ -1003,6 +992,12 @@ func (cli *Instance) moveSecretWithinVault(
 		return fmt.Errorf("secret '%s' %w", source, errMoveOntoItself)
 	}
 
+	release, err := vault.LockStateDir(cli.fs, cli.stateDir)
+	if err != nil {
+		return err
+	}
+	defer release()
+
 	vaultDir, err := vlt.GetDirectory()
 	if err != nil {
 		return err
@@ -1089,50 +1084,25 @@ func (cli *Instance) sameDirectory(dir, other string) (bool, error) {
 
 // moveSecretCrossVault handles moving between two different vaults. Its
 // caller, MoveSecret, has already checked both secret names and that both
-// vaults exist.
+// vaults exist. The copy needs the source vault's long-term key; the
+// destination vault is unlocked only to check that it can be. Either can ask
+// for a passphrase, so both happen before it takes the state directory lock,
+// and no other command waits while the user answers.
 func (cli *Instance) moveSecretCrossVault(
 	cmd *cobra.Command,
 	srcVault *vault.Vault, srcSecretName string,
 	destVault *vault.Vault, destSecretName string,
 	force bool,
 ) error {
-	srcVaultDir, err := srcVault.GetDirectory()
-	if err != nil {
-		return fmt.Errorf("failed to get source vault directory: %w", err)
-	}
-
-	// Verify source secret exists
-	srcStorageName := strings.ReplaceAll(srcSecretName, "/", "%")
-	srcSecretDir := filepath.Join(srcVaultDir, "secrets.d", srcStorageName)
-
-	exists, err := afero.DirExists(cli.fs, srcSecretDir)
-	if err != nil || !exists {
-		return fmt.Errorf("secret '%s' %w in vault '%s'",
-			srcSecretName, vault.ErrSecretNotFound, srcVault.Name)
-	}
-
-	// The source is removed after the copy, so a destination that is the
-	// source under another name would be lost with it.
-	destVaultDir, err := destVault.GetDirectory()
-	if err != nil {
-		return fmt.Errorf("failed to get destination vault directory: %w", err)
-	}
-
-	destStorageName := strings.ReplaceAll(destSecretName, "/", "%")
-	destSecretDir := filepath.Join(destVaultDir, "secrets.d", destStorageName)
-
-	same, err := cli.sameDirectory(srcSecretDir, destSecretDir)
+	// Before unlocking, check that the source secret and the destination
+	// vault exist, and that the destination is not the source under another
+	// name
+	_, err := cli.checkCrossVaultMove(
+		srcVault, srcSecretName, destVault, destSecretName)
 	if err != nil {
 		return err
 	}
 
-	if same {
-		return fmt.Errorf("secret '%s:%s' %w: '%s:%s' is the same secret on "+
-			"this filesystem", srcVault.Name, srcSecretName, errMoveOntoItself,
-			destVault.Name, destSecretName)
-	}
-
-	// Copying needs the long-term keys of both vaults
 	srcVault.Mnemonic, srcVault.UnlockPassphrase = cli.Mnemonic, cli.UnlockPassphrase
 	destVault.Mnemonic, destVault.UnlockPassphrase = cli.Mnemonic, cli.UnlockPassphrase
 
@@ -1142,6 +1112,39 @@ func (cli *Instance) moveSecretCrossVault(
 		return fmt.Errorf("failed to unlock destination vault '%s': %w", destVault.Name, err)
 	}
 
+	_, err = srcVault.GetOrDeriveLongTermKey()
+	if err != nil {
+		return fmt.Errorf("failed to unlock source vault '%s': %w",
+			srcVault.Name, err)
+	}
+
+	release, err := vault.LockStateDir(cli.fs, cli.stateDir)
+	if err != nil {
+		return err
+	}
+	defer release()
+
+	return cli.copySecretAndRemoveSource(
+		cmd, srcVault, srcSecretName, destVault, destSecretName, force)
+}
+
+// copySecretAndRemoveSource copies the secret srcSecretName of srcVault,
+// with all its versions, to destSecretName in destVault, and removes the
+// source. moveSecretCrossVault calls it holding the state directory lock.
+// Another command may have changed either vault since moveSecretCrossVault
+// checked them, so it checks them again first.
+func (cli *Instance) copySecretAndRemoveSource(
+	cmd *cobra.Command,
+	srcVault *vault.Vault, srcSecretName string,
+	destVault *vault.Vault, destSecretName string,
+	force bool,
+) error {
+	srcSecretDir, err := cli.checkCrossVaultMove(
+		srcVault, srcSecretName, destVault, destSecretName)
+	if err != nil {
+		return err
+	}
+
 	// Count versions for user feedback
 	versions, _ := secret.ListVersions(cli.fs, srcSecretDir)
 	versionCount := len(versions)
@@ -1167,6 +1170,57 @@ func (cli *Instance) moveSecretCrossVault(
 	return nil
 }
 
+// checkCrossVaultMove checks that the secret srcSecretName exists in
+// srcVault, that destVault exists, and that destSecretName in destVault is
+// not the source under another name. It returns the source's directory.
+func (cli *Instance) checkCrossVaultMove(
+	srcVault *vault.Vault, srcSecretName string,
+	destVault *vault.Vault, destSecretName string,
+) (string, error) {
+	srcVaultDir, err := srcVault.GetDirectory()
+	if err != nil {
+		return "", fmt.Errorf("failed to get source vault directory: %w", err)
+	}
+
+	// Verify source secret exists
+	srcStorageName := strings.ReplaceAll(srcSecretName, "/", "%")
+	srcSecretDir := filepath.Join(srcVaultDir, "secrets.d", srcStorageName)
+
+	exists, err := afero.DirExists(cli.fs, srcSecretDir)
+	if err != nil || !exists {
+		return "", fmt.Errorf("secret '%s' %w in vault '%s'",
+			srcSecretName, vault.ErrSecretNotFound, srcVault.Name)
+	}
+
+	_, err = cli.existingVault(destVault.Name)
+	if err != nil {
+		return "", err
+	}
+
+	// The source is removed after the copy, so a destination that is the
+	// source under another name would be lost with it.
+	destVaultDir, err := destVault.GetDirectory()
+	if err != nil {
+		return "", fmt.Errorf("failed to get destination vault directory: %w", err)
+	}
+
+	destStorageName := strings.ReplaceAll(destSecretName, "/", "%")
+	destSecretDir := filepath.Join(destVaultDir, "secrets.d", destStorageName)
+
+	same, err := cli.sameDirectory(srcSecretDir, destSecretDir)
+	if err != nil {
+		return "", err
+	}
+
+	if same {
+		return "", fmt.Errorf("secret '%s:%s' %w: '%s:%s' is the same secret "+
+			"on this filesystem", srcVault.Name, srcSecretName, errMoveOntoItself,
+			destVault.Name, destSecretName)
+	}
+
+	return srcSecretDir, nil
+}
+
 // sourceRemovalError returns the error of a move between vaults that
 // copied all versionCount versions of the secret srcName to destName, and
 // then failed with removeErr to remove srcSecretDir, the directory of