[ML] Transforms: Align privileges checks with ML plugin. (#112970)

To check the available node count, the ML plugin has an additional privileges check before returning the result. This PR uses the same approach for the corresponding transforms node endpoint.

x-pack/plugins/transform/common/constants.ts

@@ -59,6 +59,9 @@ export const APP_CLUSTER_PRIVILEGES = [
   'cluster:admin/transform/stop',
 ];
 
+// Minimum privileges required to return transform node count
+export const NODES_INFO_PRIVILEGES = ['cluster:monitor/transform/get'];
+
 // Equivalent of capabilities.canGetTransform
 export const APP_GET_TRANSFORM_CLUSTER_PRIVILEGES = [
   'cluster.cluster:monitor/transform/get',

x-pack/plugins/transform/server/routes/api/transforms_nodes.ts

@@ -5,6 +5,9 @@
  * 2.0.
  */
 
+import Boom from '@hapi/boom';
+
+import { NODES_INFO_PRIVILEGES } from '../../../common/constants';
 import { isPopulatedObject } from '../../../common/shared_imports';
 
 import { RouteDependencies } from '../../types';
@@ -44,6 +47,22 @@ export function registerTransformNodesRoutes({ router, license }: RouteDependenc
     },
     license.guardApiRoute<undefined, undefined, undefined>(async (ctx, req, res) => {
       try {
+        // If security is enabled, check that the user has at least permission to
+        // view transforms before calling the _nodes endpoint with the internal user.
+        if (license.getStatus().isSecurityEnabled === true) {
+          const {
+            body: { has_all_requested: hasAllPrivileges },
+          } = await ctx.core.elasticsearch.client.asCurrentUser.security.hasPrivileges({
+            body: {
+              cluster: NODES_INFO_PRIVILEGES,
+            },
+          });
+
+          if (!hasAllPrivileges) {
+            return res.customError(wrapError(new Boom.Boom('Forbidden', { statusCode: 403 })));
+          }
+        }
+
         const {
           body: { nodes },
         } = await ctx.core.elasticsearch.client.asInternalUser.nodes.info({

x-pack/test/api_integration/apis/transform/transforms_nodes.ts

@@ -31,7 +31,7 @@ export default ({ getService }: FtrProviderContext) => {
   }
 
   describe('/api/transform/transforms/_nodes', function () {
-    it('should return the number of available transform nodes', async () => {
+    it('should return the number of available transform nodes for a power user', async () => {
       const { body } = await supertest
         .get('/api/transform/transforms/_nodes')
         .auth(
@@ -44,5 +44,31 @@ export default ({ getService }: FtrProviderContext) => {
 
       assertTransformsNodesResponseBody(body);
     });
+
+    it('should return the number of available transform nodes for a viewer user', async () => {
+      const { body } = await supertest
+        .get('/api/transform/transforms/_nodes')
+        .auth(
+          USER.TRANSFORM_VIEWER,
+          transform.securityCommon.getPasswordForUser(USER.TRANSFORM_VIEWER)
+        )
+        .set(COMMON_REQUEST_HEADERS)
+        .send()
+        .expect(200);
+
+      assertTransformsNodesResponseBody(body);
+    });
+
+    it('should not return the number of available transform nodes for an unauthorized user', async () => {
+      await supertest
+        .get('/api/transform/transforms/_nodes')
+        .auth(
+          USER.TRANSFORM_UNAUTHORIZED,
+          transform.securityCommon.getPasswordForUser(USER.TRANSFORM_UNAUTHORIZED)
+        )
+        .set(COMMON_REQUEST_HEADERS)
+        .send()
+        .expect(403);
+    });
   });
 };

x-pack/test/functional/services/transform/security_common.ts

@@ -14,6 +14,7 @@ export type TransformSecurityCommon = ProvidedType<typeof TransformSecurityCommo
 export enum USER {
   TRANSFORM_POWERUSER = 'transform_poweruser',
   TRANSFORM_VIEWER = 'transform_viewer',
+  TRANSFORM_UNAUTHORIZED = 'transform_unauthorized',
 }
 
 export function TransformSecurityCommonProvider({ getService }: FtrProviderContext) {
@@ -69,6 +70,12 @@ export function TransformSecurityCommonProvider({ getService }: FtrProviderConte
       password: 'tfv001',
       roles: ['kibana_admin', 'transform_user', 'transform_dest_readonly'],
     },
+    {
+      name: 'transform_unauthorized',
+      full_name: 'Transform Unauthorized',
+      password: 'tfu001',
+      roles: ['kibana_admin'],
+    },
   ];
 
   return {