Allow read template with cluster monitor privilege (elastic#82046)

All three template types (legacy templates, composable index templates
and component templates) are stored in cluster state metadata (in fields
"templates", "index_template" and "component_template"). This cluster
state is readable (via GET /_cluster/state) for users who have the
monitor privilege at the cluster level. However, calling the explicit
read endpoints for these templates required the manage_index_templates
privilege. This change grants access to the template specific retrieval
APIs for all users (or API Keys) with the cluster monitor privilege so
that they can make use of these fit-for-purpose APIs instead of parsing
data directly from cluster metadata Relates:
elastic/beats#29554 Relates: elastic#78832

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/security/authz/privilege/ClusterPrivilegeResolver.java

@@ -15,6 +15,9 @@
 import org.elasticsearch.action.admin.cluster.snapshots.get.GetSnapshotsAction;
 import org.elasticsearch.action.admin.cluster.snapshots.status.SnapshotsStatusAction;
 import org.elasticsearch.action.admin.cluster.state.ClusterStateAction;
+import org.elasticsearch.action.admin.indices.template.get.GetComponentTemplateAction;
+import org.elasticsearch.action.admin.indices.template.get.GetComposableIndexTemplateAction;
+import org.elasticsearch.action.admin.indices.template.get.GetIndexTemplatesAction;
 import org.elasticsearch.action.ingest.GetPipelineAction;
 import org.elasticsearch.action.ingest.SimulatePipelineAction;
 import org.elasticsearch.common.Strings;
@@ -64,7 +67,12 @@ public class ClusterPrivilegeResolver {
     private static final Set<String> MANAGE_API_KEY_PATTERN = Set.of("cluster:admin/xpack/security/api_key/*");
     private static final Set<String> MANAGE_SERVICE_ACCOUNT_PATTERN = Set.of("cluster:admin/xpack/security/service_account/*");
     private static final Set<String> GRANT_API_KEY_PATTERN = Set.of(GrantApiKeyAction.NAME + "*");
-    private static final Set<String> MONITOR_PATTERN = Set.of("cluster:monitor/*");
+    private static final Set<String> MONITOR_PATTERN = Set.of(
+        "cluster:monitor/*",
+        GetIndexTemplatesAction.NAME,
+        GetComponentTemplateAction.NAME,
+        GetComposableIndexTemplateAction.NAME
+    );
     private static final Set<String> MONITOR_ML_PATTERN = Set.of("cluster:monitor/xpack/ml/*");
     private static final Set<String> MONITOR_TEXT_STRUCTURE_PATTERN = Set.of("cluster:monitor/text_structure/*");
     private static final Set<String> MONITOR_TRANSFORM_PATTERN = Set.of("cluster:monitor/data_frame/*", "cluster:monitor/transform/*");

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/security/authz/privilege/ClusterPrivilegeTests.java

@@ -8,16 +8,31 @@
 package org.elasticsearch.xpack.core.security.authz.privilege;
 
 import org.elasticsearch.action.ActionType;
+import org.elasticsearch.action.admin.indices.template.get.GetComponentTemplateAction;
+import org.elasticsearch.action.admin.indices.template.get.GetComposableIndexTemplateAction;
+import org.elasticsearch.action.admin.indices.template.get.GetIndexTemplatesAction;
 import org.elasticsearch.test.ESTestCase;
 import org.elasticsearch.xpack.core.enrich.action.EnrichStatsAction;
 import org.elasticsearch.xpack.core.security.authz.permission.ClusterPermission;
 
+import java.util.List;
+
 public class ClusterPrivilegeTests extends ESTestCase {
 
     public void testMonitorPrivilegeWillGrantActions() {
         assertGranted(ClusterPrivilegeResolver.MONITOR, EnrichStatsAction.INSTANCE);
     }
 
+    public void testMonitorPrivilegeGrantsGetTemplateActions() {
+        for (var action : List.of(
+            GetComponentTemplateAction.INSTANCE,
+            GetComposableIndexTemplateAction.INSTANCE,
+            GetIndexTemplatesAction.INSTANCE
+        )) {
+            assertGranted(ClusterPrivilegeResolver.MONITOR, action);
+        }
+    }
+
     public static void assertGranted(ClusterPrivilege clusterPrivilege, ActionType<?> actionType) {
         assertTrue(clusterPrivilege.buildPermission(ClusterPermission.builder()).build().check(actionType.name(), null, null));
     }

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/security/authz/store/ReservedRolesStoreTests.java

@@ -1220,7 +1220,7 @@ public void testRemoteMonitoringCollectorRole() {
         assertThat(remoteMonitoringCollectorRole.cluster().check(ClusterHealthAction.NAME, request, authentication), is(true));
         assertThat(remoteMonitoringCollectorRole.cluster().check(ClusterStateAction.NAME, request, authentication), is(true));
         assertThat(remoteMonitoringCollectorRole.cluster().check(ClusterStatsAction.NAME, request, authentication), is(true));
-        assertThat(remoteMonitoringCollectorRole.cluster().check(GetIndexTemplatesAction.NAME, request, authentication), is(false));
+        assertThat(remoteMonitoringCollectorRole.cluster().check(GetIndexTemplatesAction.NAME, request, authentication), is(true));
         assertThat(remoteMonitoringCollectorRole.cluster().check(PutIndexTemplateAction.NAME, request, authentication), is(false));
         assertThat(remoteMonitoringCollectorRole.cluster().check(DeleteIndexTemplateAction.NAME, request, authentication), is(false));
         assertThat(remoteMonitoringCollectorRole.cluster().check(ClusterRerouteAction.NAME, request, authentication), is(false));

x-pack/plugin/security/src/internalClusterTest/java/org/elasticsearch/integration/ClusterPrivilegeIntegrationTests.java

@@ -127,9 +127,17 @@ public void testThatClusterPrivilegesWorkAsExpectedViaHttp() throws Exception {
         assertAccessIsAllowed("user_b", "GET", "/_nodes/stats");
         assertAccessIsAllowed("user_b", "GET", "/_nodes/hot_threads");
         assertAccessIsAllowed("user_b", "GET", "/_nodes/infos");
+        // monitoring allows template retrieval (because it's implied by having read access to cluster state
+        assertAccessIsAllowed("user_b", "GET", "/_cat/templates/" + (randomBoolean() ? "" : randomAlphaOfLengthBetween(2, 8)));
+        assertAccessIsAllowed("user_b", "GET", "/_template/");
+        assertAccessIsAllowed("user_b", "GET", "/_index_template/");
+        assertAccessIsAllowed("user_b", "GET", "/_component_template/");
         // but no admin stuff
         assertAccessIsDenied("user_b", "POST", "/_cluster/reroute");
         assertAccessIsDenied("user_b", "PUT", "/_cluster/settings", "{ \"transient\" : { \"search.default_search_timeout\": \"1m\" } }");
+        assertAccessIsDenied("user_b", "DELETE", "/_template/" + randomAlphaOfLengthBetween(2, 8));
+        assertAccessIsDenied("user_b", "DELETE", "/_index_template/" + randomAlphaOfLengthBetween(2, 8));
+        assertAccessIsDenied("user_b", "DELETE", "/_component_template/" + randomAlphaOfLengthBetween(2, 8));
 
         // sorry user_c, you are not allowed anything
         assertAccessIsDenied("user_c", "GET", "/_cluster/state");