SERVER-28347 enforce storage depth limit for user documents

Introduces a nesting depth limit for document storage, which is lower
than the hard limit for general BSONObjects. Users cannot insert
documents exceeding this limit, nor can they update a document to exceed
it.

2 files changed, 101 insertions, 0 deletions

diff --git a/src/mongo/dbtests/SConscript b/src/mongo/dbtests/SConscript
index 38dcf788f09..e99b08dab9c 100644
--- a/src/mongo/dbtests/SConscript
+++ b/src/mongo/dbtests/SConscript
@@ -67,6 +67,7 @@ dbtest = env.Program(
         'index_access_method_test.cpp',
         'indexcatalogtests.cpp',
         'indexupdatetests.cpp',
+        'insert_test.cpp',
         'jsobjtests.cpp',
         'jsontests.cpp',
         'jstests.cpp',
diff --git a/src/mongo/dbtests/insert_test.cpp b/src/mongo/dbtests/insert_test.cpp
new file mode 100644
index 00000000000..6c234b4b1da
--- /dev/null
+++ b/src/mongo/dbtests/insert_test.cpp
@@ -0,0 +1,100 @@
+/**
+ * Copyright (C) 2017 MongoDB Inc.
+ *
+ * This program is free software: you can redistribute it and/or  modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * As a special exception, the copyright holders give permission to link the
+ * code of portions of this program with the OpenSSL library under certain
+ * conditions as described in each individual source file and distribute
+ * linked combinations including the program with the OpenSSL library. You
+ * must comply with the GNU Affero General Public License in all respects
+ * for all of the code used other than as permitted herein. If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so. If you do not
+ * wish to do so, delete this exception statement from your version. If you
+ * delete this exception statement from all source files in the program,
+ * then also delete it in the license file.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/bson/bson_depth.h"
+#include "mongo/db/client.h"
+#include "mongo/db/db_raii.h"
+#include "mongo/db/ops/insert.h"
+#include "mongo/unittest/unittest.h"
+
+namespace mongo {
+namespace {
+const auto kInsertTestNss = NamespaceString{"dbtests.InsertTest"};
+
+class InsertTest : public unittest::Test {
+public:
+    InsertTest()
+        : _opCtx(cc().makeOperationContext()),
+          _lock(_opCtx.get()),
+          _autoColl(_opCtx.get(), kInsertTestNss, MODE_IX) {}
+
+    const OperationContext* getOperationContext() const {
+        return _opCtx.get();
+    }
+
+private:
+    ServiceContext::UniqueOperationContext _opCtx;
+    Lock::GlobalWrite _lock;
+    AutoGetCollection _autoColl;
+};
+
+BSONObj makeNestedObject(size_t depth) {
+    ASSERT_GTE(depth, 1U);
+
+    auto obj = BSON("a" << 1);
+    while (--depth) {
+        obj = BSON("a" << obj);
+    }
+
+    return obj;
+}
+
+BSONObj makeNestedArray(size_t depth) {
+    ASSERT_GTE(depth, 1U);
+
+    auto obj = BSON_ARRAY(1);
+    while (--depth) {
+        obj = BSON_ARRAY(obj);
+    }
+
+    return obj;
+}
+
+TEST_F(InsertTest, FixDocumentForInsertAcceptsEmptyDocuments) {
+    ASSERT_OK(fixDocumentForInsert(getOperationContext()->getServiceContext(), BSONObj()));
+}
+
+TEST_F(InsertTest, FixDocumentForInsertAcceptsDocumentsAtStorageDepthLimit) {
+    ASSERT_OK(fixDocumentForInsert(getOperationContext()->getServiceContext(),
+                                   makeNestedObject(BSONDepth::getMaxDepthForUserStorage())));
+    ASSERT_OK(fixDocumentForInsert(getOperationContext()->getServiceContext(),
+                                   makeNestedArray(BSONDepth::getMaxDepthForUserStorage())));
+}
+
+TEST_F(InsertTest, FixDocumentForInsertFailsOnDeeplyNestedDocuments) {
+    ASSERT_EQ(fixDocumentForInsert(getOperationContext()->getServiceContext(),
+                                   makeNestedObject(BSONDepth::getMaxDepthForUserStorage() + 1)),
+              ErrorCodes::Overflow);
+    ASSERT_EQ(fixDocumentForInsert(getOperationContext()->getServiceContext(),
+                                   makeNestedArray(BSONDepth::getMaxDepthForUserStorage() + 1)),
+              ErrorCodes::Overflow);
+}
+}  // namespace
+}  // namespace mongo