Create SPI to allow prohibiting certain top-level mappings

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

@@ -0,0 +1,18 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+package org.elasticsearch.index.mapper;
+
+/**
+ * No-op Default of RootObjectMapperNamespaceValidator used in non-serverless Elasticsearch envs.
+ */
+public class DefaultRootObjectMapperNamespaceValidator implements RootObjectMapperNamespaceValidator {
+    @Override
+    public void validateNamespace(ObjectMapper.Subobjects subobjects, String name) {}
+}

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

@@ -31,12 +31,23 @@ public final class MapperRegistry {
     private final Map<String, MetadataFieldMapper.TypeParser> metadataMapperParsers6x;
     private final Map<String, MetadataFieldMapper.TypeParser> metadataMapperParsers5x;
     private final Function<String, FieldPredicate> fieldFilter;
+    private final RootObjectMapperNamespaceValidator namespaceValidator;
 
     public MapperRegistry(
         Map<String, Mapper.TypeParser> mapperParsers,
         Map<String, RuntimeField.Parser> runtimeFieldParsers,
         Map<String, MetadataFieldMapper.TypeParser> metadataMapperParsers,
         Function<String, FieldPredicate> fieldFilter
+    ) {
+        this(mapperParsers, runtimeFieldParsers, metadataMapperParsers, fieldFilter, null);
+    }
+
+    public MapperRegistry(
+        Map<String, Mapper.TypeParser> mapperParsers,
+        Map<String, RuntimeField.Parser> runtimeFieldParsers,
+        Map<String, MetadataFieldMapper.TypeParser> metadataMapperParsers,
+        Function<String, FieldPredicate> fieldFilter,
+        RootObjectMapperNamespaceValidator namespaceValidator
     ) {
         this.mapperParsers = Collections.unmodifiableMap(new LinkedHashMap<>(mapperParsers));
         this.runtimeFieldParsers = runtimeFieldParsers;
@@ -50,6 +61,7 @@ public MapperRegistry(
         metadata5x.put(LegacyTypeFieldMapper.NAME, LegacyTypeFieldMapper.PARSER);
         this.metadataMapperParsers5x = metadata5x;
         this.fieldFilter = fieldFilter;
+        this.namespaceValidator = namespaceValidator;
     }
 
     /**
@@ -72,6 +84,10 @@ public Map<String, RuntimeField.Parser> getRuntimeFieldParsers() {
         return runtimeFieldParsers;
     }
 
+    public RootObjectMapperNamespaceValidator getNamespaceValidator() {
+        return namespaceValidator;
+    }
+
     /**
      * Return a map of the meta mappers that have been registered. The
      * returned map uses the name of the field as a key.

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

@@ -245,7 +245,8 @@ public MapperService(
             indexAnalyzers,
             indexSettings,
             idFieldMapper,
-            bitSetProducer
+            bitSetProducer,
+            mapperRegistry.getNamespaceValidator()
         );
         this.documentParser = new DocumentParser(parserConfiguration, this.mappingParserContextSupplier.get());
         Map<String, MetadataFieldMapper.TypeParser> metadataMapperParsers = mapperRegistry.getMetadataMapperParsers(

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

@@ -43,6 +43,7 @@ public class MappingParserContext {
     private final Function<Query, BitSetProducer> bitSetProducer;
     private final long mappingObjectDepthLimit;
     private long mappingObjectDepth = 0;
+    private final RootObjectMapperNamespaceValidator namespaceValidator;
 
     public MappingParserContext(
         Function<String, SimilarityProvider> similarityLookupService,
@@ -55,7 +56,8 @@ public MappingParserContext(
         IndexAnalyzers indexAnalyzers,
         IndexSettings indexSettings,
         IdFieldMapper idFieldMapper,
-        Function<Query, BitSetProducer> bitSetProducer
+        Function<Query, BitSetProducer> bitSetProducer,
+        RootObjectMapperNamespaceValidator namespaceValidator
     ) {
         this.similarityLookupService = similarityLookupService;
         this.typeParsers = typeParsers;
@@ -69,6 +71,40 @@ public MappingParserContext(
         this.idFieldMapper = idFieldMapper;
         this.mappingObjectDepthLimit = indexSettings.getMappingDepthLimit();
         this.bitSetProducer = bitSetProducer;
+        this.namespaceValidator = namespaceValidator;
+    }
+
+    public MappingParserContext(
+        Function<String, SimilarityProvider> similarityLookupService,
+        Function<String, Mapper.TypeParser> typeParsers,
+        Function<String, RuntimeField.Parser> runtimeFieldParsers,
+        IndexVersion indexVersionCreated,
+        Supplier<TransportVersion> clusterTransportVersion,
+        Supplier<SearchExecutionContext> searchExecutionContextSupplier,
+        ScriptCompiler scriptCompiler,
+        IndexAnalyzers indexAnalyzers,
+        IndexSettings indexSettings,
+        IdFieldMapper idFieldMapper,
+        Function<Query, BitSetProducer> bitSetProducer
+    ) {
+        this(
+            similarityLookupService,
+            typeParsers,
+            runtimeFieldParsers,
+            indexVersionCreated,
+            clusterTransportVersion,
+            searchExecutionContextSupplier,
+            scriptCompiler,
+            indexAnalyzers,
+            indexSettings,
+            idFieldMapper,
+            bitSetProducer,
+            null
+        );
+    }
+
+    public RootObjectMapperNamespaceValidator getNamespaceValidator() {
+        return namespaceValidator;
     }
 
     public IndexAnalyzers getIndexAnalyzers() {
@@ -170,7 +206,8 @@ private static class MultiFieldParserContext extends MappingParserContext {
                 in.indexAnalyzers,
                 in.indexSettings,
                 in.idFieldMapper,
-                in.bitSetProducer
+                in.bitSetProducer,
+                in.namespaceValidator
             );
         }
 
@@ -200,7 +237,8 @@ private static class DynamicTemplateParserContext extends MappingParserContext {
                 in.indexAnalyzers,
                 in.indexSettings,
                 in.idFieldMapper,
-                in.bitSetProducer
+                in.bitSetProducer,
+                in.namespaceValidator
             );
             this.dateFormatter = dateFormatter;
         }

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

@@ -548,12 +548,21 @@ public final Optional<SourceKeepMode> sourceKeepMode() {
     }
 
     @Override
-    public void validate(MappingLookup mappers) {
+    public final void validate(MappingLookup mappers) {
         for (Mapper mapper : this.mappers.values()) {
-            mapper.validate(mappers);
+            validateSubField(mapper, mappers);
         }
     }
 
+    /**
+     * This method is separated out to allow subclasses (such as RootObjectMapper) to
+     * override it and add in additional validations beyond what the mapper.validate()
+     * method will check on each mapping.
+     */
+    protected void validateSubField(Mapper mapper, MappingLookup mappers) {
+        mapper.validate(mappers);
+    }
+
     protected MapperMergeContext createChildContext(MapperMergeContext mapperMergeContext, String name) {
         return mapperMergeContext.createChildContext(name, dynamic);
     }

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

@@ -76,6 +76,7 @@ public static class Builder extends ObjectMapper.Builder {
         protected final Map<String, RuntimeField> runtimeFields = new HashMap<>();
         protected Explicit<Boolean> dateDetection = Defaults.DATE_DETECTION;
         protected Explicit<Boolean> numericDetection = Defaults.NUMERIC_DETECTION;
+        protected RootObjectMapperNamespaceValidator namespaceValidator;
 
         public Builder(String name) {
             this(name, ObjectMapper.Defaults.SUBOBJECTS);
@@ -85,6 +86,11 @@ public Builder(String name, Explicit<Subobjects> subobjects) {
             super(name, subobjects);
         }
 
+        public Builder addNamespaceValidator(RootObjectMapperNamespaceValidator namespaceValidator) {
+            this.namespaceValidator = namespaceValidator;
+            return this;
+        }
+
         public Builder dynamicDateTimeFormatter(Collection<DateFormatter> dateTimeFormatters) {
             this.dynamicDateTimeFormatters = new Explicit<>(dateTimeFormatters.toArray(new DateFormatter[0]), true);
             return this;
@@ -124,7 +130,8 @@ public RootObjectMapper build(MapperBuilderContext context) {
                 dynamicDateTimeFormatters,
                 dynamicTemplates,
                 dateDetection,
-                numericDetection
+                numericDetection,
+                namespaceValidator
             );
         }
     }
@@ -134,6 +141,7 @@ public RootObjectMapper build(MapperBuilderContext context) {
     private final Explicit<Boolean> numericDetection;
     private final Explicit<DynamicTemplate[]> dynamicTemplates;
     private final Map<String, RuntimeField> runtimeFields;
+    private final RootObjectMapperNamespaceValidator namespaceValidator;
 
     RootObjectMapper(
         String name,
@@ -146,14 +154,16 @@ public RootObjectMapper build(MapperBuilderContext context) {
         Explicit<DateFormatter[]> dynamicDateTimeFormatters,
         Explicit<DynamicTemplate[]> dynamicTemplates,
         Explicit<Boolean> dateDetection,
-        Explicit<Boolean> numericDetection
+        Explicit<Boolean> numericDetection,
+        RootObjectMapperNamespaceValidator namespaceValidator
     ) {
         super(name, name, enabled, subobjects, sourceKeepMode, dynamic, mappers);
         this.runtimeFields = runtimeFields;
         this.dynamicTemplates = dynamicTemplates;
         this.dynamicDateTimeFormatters = dynamicDateTimeFormatters;
         this.dateDetection = dateDetection;
         this.numericDetection = numericDetection;
+        this.namespaceValidator = namespaceValidator == null ? new DefaultRootObjectMapperNamespaceValidator() : namespaceValidator;
         if (sourceKeepMode.orElse(SourceKeepMode.NONE) == SourceKeepMode.ALL) {
             throw new MapperParsingException(
                 "root object can't be configured with [" + Mapper.SYNTHETIC_SOURCE_KEEP_PARAM + ":" + SourceKeepMode.ALL + "]"
@@ -182,7 +192,8 @@ RootObjectMapper withoutMappers() {
             dynamicDateTimeFormatters,
             dynamicTemplates,
             dateDetection,
-            numericDetection
+            numericDetection,
+            namespaceValidator
         );
     }
 
@@ -298,7 +309,8 @@ public RootObjectMapper merge(Mapper mergeWith, MapperMergeContext parentMergeCo
             dynamicDateTimeFormatters,
             dynamicTemplates,
             dateDetection,
-            numericDetection
+            numericDetection,
+            namespaceValidator
         );
     }
 
@@ -455,6 +467,7 @@ public static RootObjectMapper.Builder parse(String name, Map<String, Object> no
         throws MapperParsingException {
         Explicit<Subobjects> subobjects = parseSubobjects(node);
         RootObjectMapper.Builder builder = new Builder(name, subobjects);
+        builder.addNamespaceValidator(parserContext.getNamespaceValidator());
         Iterator<Map.Entry<String, Object>> iterator = node.entrySet().iterator();
         while (iterator.hasNext()) {
             Map.Entry<String, Object> entry = iterator.next();
@@ -544,4 +557,14 @@ private static boolean processField(
     public int getTotalFieldsCount() {
         return super.getTotalFieldsCount() - 1 + runtimeFields.size();
     }
+
+    /**
+     * Overrides in order to run the namespace validator first and then delegates to the
+     * standard validateSubField on the parent class
+     */
+    @Override
+    protected void validateSubField(Mapper mapper, MappingLookup mappers) {
+        namespaceValidator.validateNamespace(subobjects(), mapper.leafName());
+        super.validateSubField(mapper, mappers);
+    }
 }

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

@@ -0,0 +1,25 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+package org.elasticsearch.index.mapper;
+
+import org.elasticsearch.core.Nullable;
+
+/**
+ * SPI to inject additional rules around namespaces (top level fields) that are prohibited
+ * in Elasticsearch mappings.
+ */
+public interface RootObjectMapperNamespaceValidator {
+    /**
+     * If the namespace in the mapper is not allowed, an Exception should be thrown.
+     * @param subobjects Whether subobjects are enabled. Null is allowed
+     * @param name namespace (field name) to validate
+     */
+    void validateNamespace(@Nullable ObjectMapper.Subobjects subobjects, String name);
+}

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

@@ -189,6 +189,9 @@ static Map<String, RuntimeField> parseRuntimeFields(
                             + " Check the documentation."
                     );
                 }
+                if (parserContext.getNamespaceValidator() != null) {
+                    parserContext.getNamespaceValidator().validateNamespace(null, fieldName);
+                }
                 runtimeFields.put(fieldName, builder.apply(typeParser.parse(fieldName, propNode, parserContext)));
                 propNode.remove("type");
                 MappingParser.checkNoRemainingFields(fieldName, propNode);

server/src/main/java/org/elasticsearch/indices/IndicesModule.java

@@ -57,6 +57,7 @@
 import org.elasticsearch.index.mapper.ObjectMapper;
 import org.elasticsearch.index.mapper.PassThroughObjectMapper;
 import org.elasticsearch.index.mapper.RangeType;
+import org.elasticsearch.index.mapper.RootObjectMapperNamespaceValidator;
 import org.elasticsearch.index.mapper.RoutingFieldMapper;
 import org.elasticsearch.index.mapper.RuntimeField;
 import org.elasticsearch.index.mapper.SeqNoFieldMapper;
@@ -94,15 +95,20 @@
 public class IndicesModule extends AbstractModule {
     private final MapperRegistry mapperRegistry;
 
-    public IndicesModule(List<MapperPlugin> mapperPlugins) {
+    public IndicesModule(List<MapperPlugin> mapperPlugins, RootObjectMapperNamespaceValidator namespaceValidator) {
         this.mapperRegistry = new MapperRegistry(
             getMappers(mapperPlugins),
             getRuntimeFields(mapperPlugins),
             getMetadataMappers(mapperPlugins),
-            getFieldFilter(mapperPlugins)
+            getFieldFilter(mapperPlugins),
+            namespaceValidator
         );
     }
 
+    public IndicesModule(List<MapperPlugin> mapperPlugins) {
+        this(mapperPlugins, null);
+    }
+
     public static List<NamedWriteableRegistry.Entry> getNamedWriteables() {
         return Arrays.asList(
             new NamedWriteableRegistry.Entry(Condition.class, MinAgeCondition.NAME, MinAgeCondition::new),

server/src/main/java/org/elasticsearch/node/NodeConstruction.java

@@ -118,7 +118,9 @@
 import org.elasticsearch.index.SlowLogFields;
 import org.elasticsearch.index.analysis.AnalysisRegistry;
 import org.elasticsearch.index.engine.MergeMetrics;
+import org.elasticsearch.index.mapper.DefaultRootObjectMapperNamespaceValidator;
 import org.elasticsearch.index.mapper.MapperMetrics;
+import org.elasticsearch.index.mapper.RootObjectMapperNamespaceValidator;
 import org.elasticsearch.index.mapper.SourceFieldMetrics;
 import org.elasticsearch.index.search.stats.ShardSearchPhaseAPMMetrics;
 import org.elasticsearch.index.shard.SearchOperationListener;
@@ -698,6 +700,12 @@ private void construct(
 
         modules.bindToInstance(Tracer.class, telemetryProvider.getTracer());
 
+        RootObjectMapperNamespaceValidator namespaceValidator = pluginsService.loadSingletonServiceProvider(
+            RootObjectMapperNamespaceValidator.class,
+            () -> new DefaultRootObjectMapperNamespaceValidator()
+        );
+        modules.bindToInstance(RootObjectMapperNamespaceValidator.class, namespaceValidator);
+
         assert nodeEnvironment.nodeId() != null : "node ID must be set before constructing the Node";
         TaskManager taskManager = new TaskManager(
             settings,
@@ -814,7 +822,7 @@ private void construct(
             )::onNewInfo
         );
 
-        IndicesModule indicesModule = new IndicesModule(pluginsService.filterPlugins(MapperPlugin.class).toList());
+        IndicesModule indicesModule = new IndicesModule(pluginsService.filterPlugins(MapperPlugin.class).toList(), namespaceValidator);
         modules.add(indicesModule);
 
         modules.add(new GatewayModule());