branch-3.1: [fix](iceberg)Ensure proper authentication context before accessing Iceberg Catalog #52149

fe/fe-core/src/main/java/org/apache/doris/datasource/iceberg/IcebergExternalCatalog.java

@@ -76,6 +76,18 @@ protected void initLocalObjectsImpl() {
         metadataOps = ops;
     }
 
+    /**
+     * Returns the underlying {@link Catalog} instance used by this external catalog.
+     *
+     * <p><strong>Warning:</strong> This method does not handle any authentication logic. If the
+     * returned catalog implementation relies on external systems
+     * that require authentication — especially in environments where Kerberos is enabled — the caller is
+     * fully responsible for ensuring the appropriate authentication has been performed <em>before</em>
+     * invoking this method.
+     * <p>Failing to authenticate beforehand may result in authorization errors or IO failures.
+     *
+     * @return the underlying catalog instance
+     */
     public Catalog getCatalog() {
         makeSureInitialized();
         return ((IcebergMetadataOps) metadataOps).getCatalog();

fe/fe-core/src/main/java/org/apache/doris/datasource/iceberg/IcebergExternalDatabase.java

@@ -41,8 +41,14 @@ public IcebergExternalTable buildTableInternal(String remoteTableName, String lo
     }
 
     public String getLocation() {
-        Map<String, String> props = ((SupportsNamespaces) ((IcebergExternalCatalog) getCatalog()).getCatalog())
-                .loadNamespaceMetadata(Namespace.of(name));
-        return props.getOrDefault("location", "");
+        try {
+            return extCatalog.getPreExecutionAuthenticator().execute(() -> {
+                Map<String, String> props = ((SupportsNamespaces) ((IcebergExternalCatalog) getCatalog()).getCatalog())
+                        .loadNamespaceMetadata(Namespace.of(name));
+                return props.getOrDefault("location", "");
+            });
+        } catch (Exception e) {
+            throw new RuntimeException("Failed to get location for Iceberg database: " + name, e);
+        }
     }
 }