Check array size at parse time

server/src/internalClusterTest/java/org/elasticsearch/action/IndicesRequestIT.java

@@ -67,6 +67,8 @@
 import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.util.concurrent.ThreadContext;
+import org.elasticsearch.index.mapper.DocumentParsingException;
+import org.elasticsearch.index.mapper.MapperService;
 import org.elasticsearch.index.query.QueryBuilders;
 import org.elasticsearch.indices.TestIndexNameExpressionResolver;
 import org.elasticsearch.plugins.NetworkPlugin;
@@ -83,6 +85,8 @@
 import org.elasticsearch.transport.TransportInterceptor;
 import org.elasticsearch.transport.TransportRequest;
 import org.elasticsearch.transport.TransportRequestHandler;
+import org.elasticsearch.xcontent.XContentBuilder;
+import org.elasticsearch.xcontent.XContentFactory;
 import org.junit.After;
 import org.junit.Before;
 
@@ -100,6 +104,7 @@
 
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertNoFailuresAndResponse;
+import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.emptyIterable;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.greaterThan;
@@ -582,6 +587,36 @@ public void testSearchDfsQueryThenFetch() throws Exception {
         );
     }
 
+    public void testRejectDocumentWithTooManyArrayObjectFields() throws Exception {
+        String indexName = "array-limit-test";
+        int arrayLimit = 10;
+
+        assertAcked(
+            prepareCreate(indexName).setSettings(
+                Settings.builder().put(MapperService.INDEX_MAPPING_ARRAY_OBJECTS_LIMIT_SETTING.getKey(), arrayLimit).build()
+            )
+        );
+
+        try (XContentBuilder doc = XContentFactory.jsonBuilder()) {
+            doc.startObject();
+            doc.startArray("array");
+            for (int i = 0; i < arrayLimit + 1; i++) {
+                doc.startObject();
+                doc.field("value", i);
+                doc.endObject();
+            }
+            doc.endArray();
+            doc.endObject();
+
+            Exception e = expectThrows(DocumentParsingException.class, () -> { client().prepareIndex(indexName).setSource(doc).get(); });
+
+            assertThat(
+                e.getMessage(),
+                containsString("The number of array objects has exceeded " + "the allowed limit of [" + arrayLimit + "]")
+            );
+        }
+    }
+
     private static void assertSameIndices(IndicesRequest originalRequest, String... actions) {
         assertSameIndices(originalRequest, false, actions);
     }

server/src/main/java/org/elasticsearch/common/settings/IndexScopedSettings.java

@@ -167,6 +167,7 @@ public final class IndexScopedSettings extends AbstractScopedSettings {
                 Store.INDEX_STORE_STATS_REFRESH_INTERVAL_SETTING,
                 MapperService.INDEX_MAPPING_NESTED_FIELDS_LIMIT_SETTING,
                 MapperService.INDEX_MAPPING_NESTED_DOCS_LIMIT_SETTING,
+                MapperService.INDEX_MAPPING_ARRAY_OBJECTS_LIMIT_SETTING,
                 MapperService.INDEX_MAPPING_IGNORE_DYNAMIC_BEYOND_LIMIT_SETTING,
                 MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING,
                 MapperService.INDEX_MAPPING_DEPTH_LIMIT_SETTING,

server/src/main/java/org/elasticsearch/index/IndexSettings.java

@@ -48,6 +48,7 @@
 
 import static org.elasticsearch.cluster.metadata.IndexMetadata.SETTING_INDEX_VERSION_CREATED;
 import static org.elasticsearch.cluster.routing.allocation.ExistingShardsAllocator.EXISTING_SHARDS_ALLOCATOR_SETTING;
+import static org.elasticsearch.index.mapper.MapperService.INDEX_MAPPING_ARRAY_OBJECTS_LIMIT_SETTING;
 import static org.elasticsearch.index.mapper.MapperService.INDEX_MAPPING_DEPTH_LIMIT_SETTING;
 import static org.elasticsearch.index.mapper.MapperService.INDEX_MAPPING_DIMENSION_FIELDS_LIMIT_SETTING;
 import static org.elasticsearch.index.mapper.MapperService.INDEX_MAPPING_FIELD_NAME_LENGTH_LIMIT_SETTING;
@@ -925,6 +926,7 @@ private void setRetentionLeaseMillis(final TimeValue retentionLease) {
     private volatile String requiredPipeline;
     private volatile long mappingNestedFieldsLimit;
     private volatile long mappingNestedDocsLimit;
+    private volatile long mappingArrayObjectsLimit;
     private volatile long mappingTotalFieldsLimit;
     private volatile boolean ignoreDynamicFieldsBeyondLimit;
     private volatile long mappingDepthLimit;
@@ -1100,6 +1102,7 @@ public IndexSettings(final IndexMetadata indexMetadata, final Settings nodeSetti
         defaultPipeline = scopedSettings.get(DEFAULT_PIPELINE);
         mappingNestedFieldsLimit = scopedSettings.get(INDEX_MAPPING_NESTED_FIELDS_LIMIT_SETTING);
         mappingNestedDocsLimit = scopedSettings.get(INDEX_MAPPING_NESTED_DOCS_LIMIT_SETTING);
+        mappingArrayObjectsLimit = scopedSettings.get(INDEX_MAPPING_ARRAY_OBJECTS_LIMIT_SETTING);
         mappingTotalFieldsLimit = scopedSettings.get(INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING);
         ignoreDynamicFieldsBeyondLimit = scopedSettings.get(INDEX_MAPPING_IGNORE_DYNAMIC_BEYOND_LIMIT_SETTING);
         mappingDepthLimit = scopedSettings.get(INDEX_MAPPING_DEPTH_LIMIT_SETTING);
@@ -1215,6 +1218,7 @@ public IndexSettings(final IndexMetadata indexMetadata, final Settings nodeSetti
         scopedSettings.addSettingsUpdateConsumer(INDEX_SOFT_DELETES_RETENTION_LEASE_PERIOD_SETTING, this::setRetentionLeaseMillis);
         scopedSettings.addSettingsUpdateConsumer(INDEX_MAPPING_NESTED_FIELDS_LIMIT_SETTING, this::setMappingNestedFieldsLimit);
         scopedSettings.addSettingsUpdateConsumer(INDEX_MAPPING_NESTED_DOCS_LIMIT_SETTING, this::setMappingNestedDocsLimit);
+        scopedSettings.addSettingsUpdateConsumer(INDEX_MAPPING_ARRAY_OBJECTS_LIMIT_SETTING, this::setMappingArrayObjectsLimit);
         scopedSettings.addSettingsUpdateConsumer(
             INDEX_MAPPING_IGNORE_DYNAMIC_BEYOND_LIMIT_SETTING,
             this::setIgnoreDynamicFieldsBeyondLimit
@@ -1754,6 +1758,14 @@ private void setMappingNestedDocsLimit(long value) {
         this.mappingNestedDocsLimit = value;
     }
 
+    public long getMappingArrayObjectsLimit() {
+        return mappingArrayObjectsLimit;
+    }
+
+    private void setMappingArrayObjectsLimit(long value) {
+        this.mappingArrayObjectsLimit = value;
+    }
+
     public long getMappingTotalFieldsLimit() {
         return mappingTotalFieldsLimit;
     }

server/src/main/java/org/elasticsearch/index/mapper/DocumentParser.java

@@ -749,8 +749,20 @@ private static void parseNonDynamicArray(
         XContentParser.Token token;
         XContentParser.Token previousToken = parser.currentToken();
         int elements = 0;
+        int countArray = 0;
+        long arrayObjectsLimit = context.indexSettings().getMappingArrayObjectsLimit();
         while ((token = parser.nextToken()) != XContentParser.Token.END_ARRAY) {
             if (token == XContentParser.Token.START_OBJECT) {
+                if (countArray++ >= arrayObjectsLimit) {
+                    throw new IllegalStateException(
+                        "The number of array objects has exceeded the allowed limit of ["
+                            + arrayObjectsLimit
+                            + "]. "
+                            + "This limit can be set by changing the ["
+                            + MapperService.INDEX_MAPPING_ARRAY_OBJECTS_LIMIT_SETTING.getKey()
+                            + "] index level setting."
+                    );
+                }
                 elements = 2;
                 parseObject(context, lastFieldName);
             } else if (token == XContentParser.Token.START_ARRAY) {

server/src/main/java/org/elasticsearch/index/mapper/MapperService.java

@@ -116,6 +116,15 @@ public boolean isAutoUpdate() {
         Property.Dynamic,
         Property.IndexScope
     );
+    // maximum allowed number of objects for an array field in a document
+    public static final Setting<Long> INDEX_MAPPING_ARRAY_OBJECTS_LIMIT_SETTING = Setting.longSetting(
+        "index.mapping.array_objects.limit",
+        20000L,
+        0,
+        Property.Dynamic,
+        Property.IndexScope
+    );
+
     public static final Setting<Long> INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING = Setting.longSetting(
         "index.mapping.total_fields.limit",
         1000L,

x-pack/plugin/ccr/src/test/java/org/elasticsearch/xpack/ccr/action/TransportResumeFollowActionTests.java

@@ -322,6 +322,7 @@ public void testDynamicIndexSettingsAreClassified() {
         replicatedSettings.add(MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING);
         replicatedSettings.add(MapperService.INDEX_MAPPING_IGNORE_DYNAMIC_BEYOND_LIMIT_SETTING);
         replicatedSettings.add(MapperService.INDEX_MAPPING_NESTED_DOCS_LIMIT_SETTING);
+        replicatedSettings.add(MapperService.INDEX_MAPPING_ARRAY_OBJECTS_LIMIT_SETTING);
         replicatedSettings.add(MapperService.INDEX_MAPPING_NESTED_FIELDS_LIMIT_SETTING);
         replicatedSettings.add(MapperService.INDEX_MAPPING_DEPTH_LIMIT_SETTING);
         replicatedSettings.add(MapperService.INDEX_MAPPING_FIELD_NAME_LENGTH_LIMIT_SETTING);