ES-12969 Prohibit _reindex, _delete_by_query and _update_by_query from issuing cross-project calls

Author: alexey-ivanov-es

modules/reindex/src/main/java/org/elasticsearch/reindex/AbstractBaseReindexRestHandler.java

@@ -44,6 +44,10 @@ protected RestChannelConsumer doPrepareRequest(RestRequest request, NodeClient c
         // Build the internal request
         Request internal = setCommonOptions(request, buildRequest(request));
 
+        // Only requests supporting remote indices can have IndicesOptions allowing cross-project index expressions
+        assert internal.supportsRemoteIndicesSearch()
+            || internal.getSearchRequest().indicesOptions().resolveCrossProjectIndexExpression() == false;
+
         // Executes the request and waits for completion
         if (request.paramAsBoolean("wait_for_completion", true)) {
             Map<String, String> params = new HashMap<>();

server/src/main/java/org/elasticsearch/cluster/metadata/IndexNameExpressionResolver.java

@@ -479,18 +479,26 @@ private static void ensureRemoteExpressionRequireIgnoreUnavailable(IndicesOption
             return;
         }
         if (RemoteClusterAware.isRemoteIndexName(current)) {
-            List<String> crossClusterIndices = new ArrayList<>();
-            for (int i = 0; i < expressions.length; i++) {
-                if (RemoteClusterAware.isRemoteIndexName(expressions[i])) {
-                    crossClusterIndices.add(expressions[i]);
-                }
-            }
+            List<String> crossClusterIndices = getRemoteIndexExpressions(expressions);
             throw new IllegalArgumentException(
                 "Cross-cluster calls are not supported in this context but remote indices were requested: " + crossClusterIndices
             );
         }
     }
 
+    /**
+     * Extracts the list of remote index expressions from the given array of index expressions
+     */
+    public static List<String> getRemoteIndexExpressions(String... expressions) {
+        List<String> crossClusterIndices = new ArrayList<>();
+        for (int i = 0; i < expressions.length; i++) {
+            if (RemoteClusterAware.isRemoteIndexName(expressions[i])) {
+                crossClusterIndices.add(expressions[i]);
+            }
+        }
+        return crossClusterIndices;
+    }
+
     /**
      * Translates the provided index expression into actual concrete indices, properly deduplicated.
      *

server/src/main/java/org/elasticsearch/index/reindex/AbstractBulkByScrollRequest.java

@@ -137,6 +137,13 @@ public AbstractBulkByScrollRequest(SearchRequest searchRequest, boolean setDefau
      */
     protected abstract Self self();
 
+    /**
+     * Whether the request supports remote indices in the search request.
+     */
+    public boolean supportsRemoteIndicesSearch() {
+        return false;
+    }
+
     @Override
     public ActionRequestValidationException validate() {
         ActionRequestValidationException e = searchRequest.validate();

server/src/main/java/org/elasticsearch/index/reindex/ReindexRequest.java

@@ -83,6 +83,11 @@ protected ReindexRequest self() {
         return this;
     }
 
+    @Override
+    public boolean supportsRemoteIndicesSearch() {
+        return true;
+    }
+
     @Override
     public ActionRequestValidationException validate() {
         ActionRequestValidationException e = super.validate();

server/src/test/java/org/elasticsearch/cluster/metadata/IndexNameExpressionResolverTests.java

@@ -78,6 +78,8 @@
 import static org.hamcrest.Matchers.emptyArray;
 import static org.hamcrest.Matchers.endsWith;
 import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.hasLength;
+import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.notNullValue;
 import static org.hamcrest.Matchers.nullValue;
@@ -3486,6 +3488,18 @@ public void testResolveWriteIndexAbstractionMultipleMatches() {
         );
     }
 
+    public void testGetRemoteIndexExpressions() {
+        {
+            List<String> remoteIndexExpressions = IndexNameExpressionResolver.getRemoteIndexExpressions("index-1");
+            assertThat(remoteIndexExpressions, empty());
+        }
+        {
+            List<String> remoteIndexExpressions = IndexNameExpressionResolver.getRemoteIndexExpressions("index-1", "remote:index-1", "idx-*", "remote-2:idx-5");
+            assertThat(remoteIndexExpressions, hasSize(2));
+            assertThat(remoteIndexExpressions, contains("remote:index-1", "remote-2:idx-5"));
+        }
+    }
+
     public static IndexMetadata.Builder indexBuilder(String index) {
         return indexBuilder(index, Settings.EMPTY);
     }