Ensure we can rotate pulumi passphrase secrets providers (#5865)

Fixes: #5452

When the user is requesting to change the secrets provider to a
passphrase provider, we now calculate that has been requested.

This means, we will prompt for a new passphrase for use in encrypting
the stack.

```
pulumi stack change-secrets-provider passphrase
Enter your passphrase to unlock config/secrets
    (set PULUMI_CONFIG_PASSPHRASE or PULUMI_CONFIG_PASSPHRASE_FILE to remember):
Enter your new passphrase to protect config/secrets:
Re-enter your new passphrase to confirm:
Migrating old configuration and state to new secrets provider
Enter your passphrase to unlock config/secrets
    (set PULUMI_CONFIG_PASSPHRASE or PULUMI_CONFIG_PASSPHRASE_FILE to remember):
```

CHANGELOG.md

@@ -9,6 +9,9 @@ CHANGELOG
 - Automatically install missing Python dependencies.
   [#5787](https://github.com/pulumi/pulumi/pull/5787)
 
+- [cli] Ensure `pulumi stack change-secrets-provider` allows rotating the key for a passphrase provider
+  [#5865](https://github.com/pulumi/pulumi/pull/5865/)
+
 ## 2.15.0 (2020-12-02)
 
 - [sdk/python] Add deserialization support for enums.

pkg/cmd/pulumi/crypto.go

@@ -58,12 +58,14 @@ func getStackSecretsManager(s backend.Stack) (secrets.Manager, error) {
 		}
 
 		if ps.EncryptionSalt != "" {
-			return newPassphraseSecretsManager(s.Ref().Name(), stackConfigFile)
+			return newPassphraseSecretsManager(s.Ref().Name(), stackConfigFile,
+				false /* rotatePassphraseSecretsProvider */)
 		}
 
 		switch s.(type) {
 		case filestate.Stack:
-			return newPassphraseSecretsManager(s.Ref().Name(), stackConfigFile)
+			return newPassphraseSecretsManager(s.Ref().Name(), stackConfigFile,
+				false /* rotatePassphraseSecretsProvider */)
 		case httpstate.Stack:
 			return newServiceSecretsManager(s.(httpstate.Stack), s.Ref().Name(), stackConfigFile)
 		}

pkg/cmd/pulumi/crypto_local.go

@@ -57,7 +57,8 @@ func readPassphrase(prompt string) (phrase string, interactive bool, err error)
 	return phrase, true, err
 }
 
-func newPassphraseSecretsManager(stackName tokens.QName, configFile string) (secrets.Manager, error) {
+func newPassphraseSecretsManager(stackName tokens.QName, configFile string,
+	rotatePassphraseSecretsProvider bool) (secrets.Manager, error) {
 	contract.Assertf(stackName != "", "stackName %s", "!= \"\"")
 
 	if configFile == "" {
@@ -73,6 +74,10 @@ func newPassphraseSecretsManager(stackName tokens.QName, configFile string) (sec
 		return nil, err
 	}
 
+	if rotatePassphraseSecretsProvider {
+		info.EncryptionSalt = ""
+	}
+
 	// If we have a salt, we can just use it.
 	if info.EncryptionSalt != "" {
 		for {
@@ -99,12 +104,20 @@ func newPassphraseSecretsManager(stackName tokens.QName, configFile string) (sec
 
 	// Get a the passphrase from the user, ensuring that they match.
 	for {
+		firstMessage := "Enter your passphrase to protect config/secrets"
+		if rotatePassphraseSecretsProvider {
+			firstMessage = "Enter your new passphrase to protect config/secrets"
+		}
 		// Here, the stack does not have an EncryptionSalt, so we will get a passphrase and create one
-		first, _, err := readPassphrase("Enter your passphrase to protect config/secrets")
+		first, _, err := readPassphrase(firstMessage)
 		if err != nil {
 			return nil, err
 		}
-		second, _, err := readPassphrase("Re-enter your passphrase to confirm")
+		secondMessage := "Re-enter your passphrase to confirm"
+		if rotatePassphraseSecretsProvider {
+			secondMessage = "Re-enter your new passphrase to confirm"
+		}
+		second, _, err := readPassphrase(secondMessage)
 		if err != nil {
 			return nil, err
 		}

pkg/cmd/pulumi/stack_change_secrets_provider.go

@@ -17,7 +17,7 @@ package main
 import (
 	"context"
 	"encoding/json"
-
+	"fmt"
 	"github.com/pulumi/pulumi/pkg/v2/backend"
 	"github.com/pulumi/pulumi/pkg/v2/resource/stack"
 	"github.com/pulumi/pulumi/sdk/v2/go/common/apitype"
@@ -91,66 +91,33 @@ func newStackChangeSecretsProviderCmd() *cobra.Command {
 				decrypter = config.NewPanicCrypter()
 			}
 
+			secretsProvider := args[0]
+			rotatePassphraseProvider := secretsProvider == "passphrase"
 			// Create the new secrets provider and set to the currentStack
-			if err := createSecretsManager(b, currentStack.Ref(), args[0]); err != nil {
-				return err
-			}
-
-			// Change the config to use the new secrets provider
-			err = migrateConfigToNewSecretsProvider(currentStack, currentConfig, decrypter)
-			if err != nil {
+			if err := createSecretsManager(b, currentStack.Ref(), secretsProvider, rotatePassphraseProvider); err != nil {
 				return err
 			}
 
 			// Fixup the checkpoint
-			return migrateCheckpointToNewSecretsProvider(commandContext(), currentStack)
+			fmt.Printf("Migrating old configuration and state to new secrets provider\n")
+			return migrateOldConfigAndCheckpointToNewSecretsProvider(commandContext(), currentStack, currentConfig, decrypter)
 		}),
 	}
 
 	return cmd
 }
 
-func migrateCheckpointToNewSecretsProvider(ctx context.Context, currentStack backend.Stack) error {
-	// Load the current checkpoint so those secrets can also be decrypted
-	checkpoint, err := currentStack.ExportDeployment(ctx)
-	if err != nil {
-		return err
-	}
-	snap, err := stack.DeserializeUntypedDeployment(checkpoint, stack.DefaultSecretsProvider)
-	if err != nil {
-		return checkDeploymentVersionError(err, currentStack.Ref().Name().String())
-	}
-
+func migrateOldConfigAndCheckpointToNewSecretsProvider(ctx context.Context, currentStack backend.Stack,
+	currentConfig config.Map, decrypter config.Decrypter) error {
+	// The order of operations here should be to load the secrets manager current stack
 	// Get the newly created secrets manager for the stack
 	newSecretsManager, err := getStackSecretsManager(currentStack)
 	if err != nil {
 		return err
 	}
 
-	// Reserialize the Snapshopshot with the NewSecrets Manager
-	reserializedDeployment, err := stack.SerializeDeployment(snap, newSecretsManager, false /*showSecrets*/)
-	if err != nil {
-		return err
-	}
-
-	bytes, err := json.Marshal(reserializedDeployment)
-	if err != nil {
-		return err
-	}
-
-	dep := apitype.UntypedDeployment{
-		Version:    apitype.DeploymentSchemaVersionCurrent,
-		Deployment: bytes,
-	}
-
-	// Import the newly changes Deployment
-	return currentStack.ImportDeployment(ctx, &dep)
-}
-
-func migrateConfigToNewSecretsProvider(currentStack backend.Stack, currentConfig config.Map,
-	decrypter config.Decrypter) error {
-	// Get the new encrypter for the current stack
-	newEncrypter, err := getStackEncrypter(currentStack)
+	// get the encrypter for the new secrets manager
+	newEncrypter, err := newSecretsManager.Encrypter()
 	if err != nil {
 		return err
 	}
@@ -173,5 +140,36 @@ func migrateConfigToNewSecretsProvider(currentStack backend.Stack, currentConfig
 		}
 	}
 
-	return saveProjectStack(currentStack, reloadedProjectStack)
+	if err := saveProjectStack(currentStack, reloadedProjectStack); err != nil {
+		return err
+	}
+
+	// Load the current checkpoint so those secrets can also be decrypted
+	checkpoint, err := currentStack.ExportDeployment(ctx)
+	if err != nil {
+		return err
+	}
+	snap, err := stack.DeserializeUntypedDeployment(checkpoint, stack.DefaultSecretsProvider)
+	if err != nil {
+		return checkDeploymentVersionError(err, currentStack.Ref().Name().String())
+	}
+
+	// Reserialize the Snapshopshot with the NewSecrets Manager
+	reserializedDeployment, err := stack.SerializeDeployment(snap, newSecretsManager, false /*showSecrets*/)
+	if err != nil {
+		return err
+	}
+
+	bytes, err := json.Marshal(reserializedDeployment)
+	if err != nil {
+		return err
+	}
+
+	dep := apitype.UntypedDeployment{
+		Version:    apitype.DeploymentSchemaVersionCurrent,
+		Deployment: bytes,
+	}
+
+	// Import the newly changes Deployment
+	return currentStack.ImportDeployment(ctx, &dep)
 }

pkg/cmd/pulumi/util.go

@@ -119,11 +119,13 @@ func commandContext() context.Context {
 	return ctx
 }
 
-func createSecretsManager(b backend.Backend, stackRef backend.StackReference, secretsProvider string) error {
+func createSecretsManager(b backend.Backend, stackRef backend.StackReference, secretsProvider string,
+	rotatePassphraseSecretsProvider bool) error {
 	// As part of creating the stack, we also need to configure the secrets provider for the stack.
 	// We need to do this configuration step for cases where we will be using with the passphrase
 	// secrets provider or one of the cloud-backed secrets providers.  We do not need to do this
 	// for the Pulumi service backend secrets provider.
+	// we have an explicit flag to rotate the secrets manager ONLY when it's a passphrase!
 	isDefaultSecretsProvider := secretsProvider == "" || secretsProvider == "default"
 	if _, ok := b.(filestate.Backend); ok && isDefaultSecretsProvider {
 		// The default when using the filestate backend is the passphrase secrets provider
@@ -148,7 +150,8 @@ func createSecretsManager(b backend.Backend, stackRef backend.StackReference, se
 	}
 
 	if secretsProvider == passphrase.Type {
-		if _, pharseErr := newPassphraseSecretsManager(stackRef.Name(), stackConfigFile); pharseErr != nil {
+		if _, pharseErr := newPassphraseSecretsManager(stackRef.Name(), stackConfigFile,
+			rotatePassphraseSecretsProvider); pharseErr != nil {
 			return pharseErr
 		}
 	} else if !isDefaultSecretsProvider {
@@ -194,7 +197,8 @@ func createStack(
 		return nil, errors.Wrapf(err, "could not create stack")
 	}
 
-	if err := createSecretsManager(b, stackRef, secretsProvider); err != nil {
+	if err := createSecretsManager(b, stackRef, secretsProvider,
+		false /* rotateSecretsManager */); err != nil {
 		return nil, err
 	}