Auth: Add functional option for static requester methods (#107581)

* Auth: Add functional option for static requester methods

Initially supporting WithServiceIdentityName to set a ServiceIdentity
inside the Claims.Rest object, so that Secrets Manager can parse
the service requesting secret decryption.

On Secret creation, the service will have to pass its identity
(which is a freeform string) to the SecureValues' Decrypters object.

This field gates which services are allowed to decrypt the SecureValue.

And upon decryption, the service should build a static identity with
that same service identity name when calling the decrypt service.

* StaticRequester: Put secret decrypt permission in access token claims

* StaticRequester: Inline getTokenPermissions function

pkg/apimachinery/identity/context.go

@@ -36,8 +36,22 @@ const (
 	serviceNameForProvisioning = "provisioning"
 )
 
-func newInternalIdentity(name string, namespace string, orgID int64) Requester {
-	return &StaticRequester{
+type IdentityOpts func(*StaticRequester)
+
+// WithServiceIdentityName sets the `StaticRequester.AccessTokenClaims.Rest.ServiceIdentity` field to the provided name.
+// This is so far only used by Secrets Manager to identify and gate the service decrypting a secret.
+func WithServiceIdentityName(name string) IdentityOpts {
+	return func(r *StaticRequester) {
+		r.AccessTokenClaims.Rest.ServiceIdentity = name
+	}
+}
+
+func newInternalIdentity(name string, namespace string, orgID int64, opts ...IdentityOpts) Requester {
+	// Create a copy of the ServiceIdentityClaims to avoid modifying the global one.
+	// Some of the options might mutate it.
+	claimsCopy := *ServiceIdentityClaims
+
+	staticRequester := &StaticRequester{
 		Type:           types.TypeAccessPolicy,
 		Name:           name,
 		UserUID:        name,
@@ -50,37 +64,43 @@ func newInternalIdentity(name string, namespace string, orgID int64) Requester {
 		Permissions: map[int64]map[string][]string{
 			orgID: serviceIdentityPermissions,
 		},
-		AccessTokenClaims: ServiceIdentityClaims,
+		AccessTokenClaims: &claimsCopy,
+	}
+
+	for _, opt := range opts {
+		opt(staticRequester)
 	}
+
+	return staticRequester
 }
 
 // WithServiceIdentity sets an identity representing the service itself in provided org and store it in context.
 // This is useful for background tasks that has to communicate with unfied storage. It also returns a Requester with
 // static permissions so it can be used in legacy code paths.
-func WithServiceIdentity(ctx context.Context, orgID int64) (context.Context, Requester) {
-	r := newInternalIdentity(serviceName, "*", orgID)
+func WithServiceIdentity(ctx context.Context, orgID int64, opts ...IdentityOpts) (context.Context, Requester) {
+	r := newInternalIdentity(serviceName, "*", orgID, opts...)
 	return WithRequester(ctx, r), r
 }
 
-func WithProvisioningIdentity(ctx context.Context, namespace string) (context.Context, Requester, error) {
+func WithProvisioningIdentity(ctx context.Context, namespace string, opts ...IdentityOpts) (context.Context, Requester, error) {
 	ns, err := types.ParseNamespace(namespace)
 	if err != nil {
 		return nil, nil, err
 	}
 
-	r := newInternalIdentity(serviceNameForProvisioning, ns.Value, ns.OrgID)
+	r := newInternalIdentity(serviceNameForProvisioning, ns.Value, ns.OrgID, opts...)
 	return WithRequester(ctx, r), r, nil
 }
 
 // WithServiceIdentityContext sets an identity representing the service itself in context.
-func WithServiceIdentityContext(ctx context.Context, orgID int64) context.Context {
-	ctx, _ = WithServiceIdentity(ctx, orgID)
+func WithServiceIdentityContext(ctx context.Context, orgID int64, opts ...IdentityOpts) context.Context {
+	ctx, _ = WithServiceIdentity(ctx, orgID, opts...)
 	return ctx
 }
 
 // WithServiceIdentityFN calls provided closure with an context contaning the identity of the service.
-func WithServiceIdentityFn[T any](ctx context.Context, orgID int64, fn func(ctx context.Context) (T, error)) (T, error) {
-	return fn(WithServiceIdentityContext(ctx, orgID))
+func WithServiceIdentityFn[T any](ctx context.Context, orgID int64, fn func(ctx context.Context) (T, error), opts ...IdentityOpts) (T, error) {
+	return fn(WithServiceIdentityContext(ctx, orgID, opts...))
 }
 
 func getWildcardPermissions(actions ...string) map[string][]string {
@@ -91,14 +111,6 @@ func getWildcardPermissions(actions ...string) map[string][]string {
 	return permissions
 }
 
-func getTokenPermissions(groups ...string) []string {
-	out := make([]string, 0, len(groups))
-	for _, group := range groups {
-		out = append(out, group+":*")
-	}
-	return out
-}
-
 // serviceIdentityPermissions is a list of wildcard permissions for provided actions.
 // We should add every action required "internally" here.
 var serviceIdentityPermissions = getWildcardPermissions(
@@ -121,13 +133,16 @@ var serviceIdentityPermissions = getWildcardPermissions(
 	"serviceaccounts:read", // serviceaccounts.ActionRead,
 )
 
-var serviceIdentityTokenPermissions = getTokenPermissions(
-	"folder.grafana.app",
-	"dashboard.grafana.app",
-	"secret.grafana.app",
-	"query.grafana.app",
-	"iam.grafana.app",
-)
+var serviceIdentityTokenPermissions = []string{
+	"folder.grafana.app:*",
+	"dashboard.grafana.app:*",
+	"secret.grafana.app:*",
+	"query.grafana.app:*",
+	"iam.grafana.app:*",
+
+	// Secrets Manager uses a custom verb for secret decryption, and its authorizer does not allow wildcard permissions.
+	"secret.grafana.app/securevalues:decrypt",
+}
 
 var ServiceIdentityClaims = &authn.Claims[authn.AccessTokenClaims]{
 	Rest: authn.AccessTokenClaims{

pkg/apimachinery/identity/context_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"testing"
 
+	"github.com/grafana/authlib/authn"
 	"github.com/stretchr/testify/require"
 
 	"github.com/grafana/grafana/pkg/apimachinery/identity"
@@ -24,3 +25,48 @@ func TestRequesterFromContext(t *testing.T) {
 		require.Equal(t, expected.GetUID(), actual.GetUID())
 	})
 }
+
+func TestWithServiceIdentity(t *testing.T) {
+	t.Run("with a custom service identity name", func(t *testing.T) {
+		customName := "custom-service"
+		orgID := int64(1)
+		ctx, requester := identity.WithServiceIdentity(context.Background(), orgID, identity.WithServiceIdentityName(customName))
+		require.NotNil(t, requester)
+		require.Equal(t, orgID, requester.GetOrgID())
+		require.Equal(t, customName, requester.GetExtra()[string(authn.ServiceIdentityKey)][0])
+		require.Contains(t, requester.GetTokenPermissions(), "secret.grafana.app/securevalues:decrypt")
+
+		fromCtx, err := identity.GetRequester(ctx)
+		require.NoError(t, err)
+		require.Equal(t, customName, fromCtx.GetExtra()[string(authn.ServiceIdentityKey)][0])
+
+		// Reuse the context but create another identity on top with a different name and org ID
+		anotherCustomName := "another-custom-service"
+		anotherOrgID := int64(2)
+		ctx2 := identity.WithServiceIdentityContext(ctx, anotherOrgID, identity.WithServiceIdentityName(anotherCustomName))
+
+		fromCtx, err = identity.GetRequester(ctx2)
+		require.NoError(t, err)
+		require.Equal(t, anotherOrgID, fromCtx.GetOrgID())
+		require.Equal(t, anotherCustomName, fromCtx.GetExtra()[string(authn.ServiceIdentityKey)][0])
+
+		// Reuse the context but create another identity without a custom name
+		ctx3, requester := identity.WithServiceIdentity(ctx2, 1)
+		require.NotNil(t, requester)
+		require.Empty(t, requester.GetExtra()[string(authn.ServiceIdentityKey)])
+
+		fromCtx, err = identity.GetRequester(ctx3)
+		require.NoError(t, err)
+		require.Empty(t, fromCtx.GetExtra()[string(authn.ServiceIdentityKey)])
+	})
+
+	t.Run("without a custom service identity name", func(t *testing.T) {
+		ctx, requester := identity.WithServiceIdentity(context.Background(), 1)
+		require.NotNil(t, requester)
+		require.Empty(t, requester.GetExtra()[string(authn.ServiceIdentityKey)])
+
+		fromCtx, err := identity.GetRequester(ctx)
+		require.NoError(t, err)
+		require.Empty(t, fromCtx.GetExtra()[string(authn.ServiceIdentityKey)])
+	})
+}