systemview: adds method for plugins to generate identity tokens (#24929)

* systemview: adds method for plugins to generate identity tokens

* change test name and godoc

* adds changelog

* make proto to include comment

changelog/24929.txt

@@ -0,0 +1,3 @@
+```release-note:improvement
+sdk: adds new method to system view to allow plugins to request identity tokens
+```

sdk/helper/pluginutil/identity_token.go

@@ -0,0 +1,40 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package pluginutil
+
+import (
+	"time"
+)
+
+const redactedTokenString = "ey***"
+
+type IdentityTokenRequest struct {
+	// Audience identifies the recipient of the token. The requested
+	// value will be in the "aud" claim. Required.
+	Audience string
+	// TTL is the requested duration that the token will be valid for.
+	// Optional with a default of 1hr.
+	TTL time.Duration
+}
+
+type IdentityTokenResponse struct {
+	// Token is the plugin identity token.
+	Token IdentityToken
+	// TTL is the duration that the token is valid for after truncation is applied.
+	// The TTL may be truncated depending on the lifecycle of its signing key.
+	TTL time.Duration
+}
+
+type IdentityToken string
+
+// String returns a redacted token string. Use the Token() method
+// to obtain the non-redacted token contents.
+func (t IdentityToken) String() string {
+	return redactedTokenString
+}
+
+// Token returns the non-redacted token contents.
+func (t IdentityToken) Token() string {
+	return string(t)
+}

sdk/helper/pluginutil/identity_token_test.go

@@ -0,0 +1,29 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package pluginutil
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// TestIdentityToken_Stringer ensures that plugin identity tokens that
+// are printed in formatted strings or errors are redacted and getters
+// return expected values.
+func TestIdentityToken_Stringer(t *testing.T) {
+	contents := "header.payload.signature"
+	tk := IdentityToken(contents)
+
+	// token getters
+	assert.Equal(t, contents, tk.Token())
+	assert.Equal(t, redactedTokenString, tk.String())
+
+	// formatted strings and errors
+	assert.NotContains(t, fmt.Sprintf("%v", tk), tk.Token())
+	assert.NotContains(t, fmt.Sprintf("%s", tk), tk.Token())
+	assert.NotContains(t, fmt.Errorf("%v", tk).Error(), tk.Token())
+	assert.NotContains(t, fmt.Errorf("%s", tk).Error(), tk.Token())
+}

sdk/logical/system_view.go

@@ -97,6 +97,9 @@ type SystemView interface {
 	// write forwarding (WriteForwardedPaths). This value will be templated
 	// in for the {{cluterId}} sentinel.
 	ClusterID(ctx context.Context) (string, error)
+
+	// GenerateIdentityToken returns an identity token for the requesting plugin.
+	GenerateIdentityToken(ctx context.Context, req *pluginutil.IdentityTokenRequest) (*pluginutil.IdentityTokenResponse, error)
 }
 
 type PasswordPolicy interface {
@@ -265,6 +268,10 @@ func (d StaticSystemView) ClusterID(ctx context.Context) (string, error) {
 	return d.ClusterUUID, nil
 }
 
+func (d StaticSystemView) GenerateIdentityToken(_ context.Context, _ *pluginutil.IdentityTokenRequest) (*pluginutil.IdentityTokenResponse, error) {
+	return nil, errors.New("GenerateIdentityToken is not implemented in StaticSystemView")
+}
+
 func (d StaticSystemView) APILockShouldBlockRequest() (bool, error) {
 	return d.APILockShouldBlockRequestVal, nil
 }

sdk/plugin/grpc_system.go

@@ -211,6 +211,21 @@ func (s gRPCSystemViewClient) ClusterID(ctx context.Context) (string, error) {
 	return reply.ClusterID, nil
 }
 
+func (s *gRPCSystemViewClient) GenerateIdentityToken(ctx context.Context, req *pluginutil.IdentityTokenRequest) (*pluginutil.IdentityTokenResponse, error) {
+	resp, err := s.client.GenerateIdentityToken(ctx, &pb.GenerateIdentityTokenRequest{
+		Audience: req.Audience,
+		TTL:      int64(req.TTL.Seconds()),
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return &pluginutil.IdentityTokenResponse{
+		Token: pluginutil.IdentityToken(resp.Token),
+		TTL:   time.Duration(resp.TTL) * time.Second,
+	}, nil
+}
+
 type gRPCSystemViewServer struct {
 	pb.UnimplementedSystemViewServer
 
@@ -394,3 +409,23 @@ func (s *gRPCSystemViewServer) ClusterInfo(ctx context.Context, _ *pb.Empty) (*p
 		ClusterID: clusterId,
 	}, nil
 }
+
+func (s *gRPCSystemViewServer) GenerateIdentityToken(ctx context.Context, req *pb.GenerateIdentityTokenRequest) (*pb.GenerateIdentityTokenResponse, error) {
+	if s.impl == nil {
+		return nil, errMissingSystemView
+	}
+
+	res, err := s.impl.GenerateIdentityToken(ctx, &pluginutil.IdentityTokenRequest{
+		Audience: req.GetAudience(),
+		TTL:      time.Duration(req.GetTTL()) * time.Second,
+	})
+	if err != nil {
+		return &pb.GenerateIdentityTokenResponse{}, status.Errorf(codes.Internal,
+			"failed to generate plugin identity token")
+	}
+
+	return &pb.GenerateIdentityTokenResponse{
+		Token: res.Token.Token(),
+		TTL:   int64(res.TTL.Seconds()),
+	}, nil
+}