SERVER-20858 Reject creation of non-capped oplog collections.

(cherry picked from commit bee7144f59bc8782c3c8e76c45a9f9e0e39cb1e6)

2 files changed, 39 insertions, 0 deletions

diff --git a/jstests/noPassthrough/noncapped_oplog_creation.js b/jstests/noPassthrough/noncapped_oplog_creation.js
new file mode 100644
index 00000000000..87dc37e6ed6
--- /dev/null
+++ b/jstests/noPassthrough/noncapped_oplog_creation.js
@@ -0,0 +1,38 @@
+/**
+ * Test that the server returns an error response for operations that attempt to create a non-capped
+ * oplog collection.
+ */
+(function() {
+    'use strict';
+
+    var dbpath = MongoRunner.dataPath + 'noncapped_oplog_creation';
+    resetDbpath(dbpath);
+
+    var conn = MongoRunner.runMongod({
+        dbpath: dbpath,
+        noCleanData: true,
+    });
+    assert.neq(null, conn, 'mongod was unable to start up');
+
+    var localDB = conn.getDB('local');
+
+    // Test that explicitly creating a non-capped oplog collection fails.
+    assert.commandFailed(localDB.createCollection('oplog.fake', {capped: false}));
+
+    // Test that inserting into the replica set oplog fails when implicitly creating a non-capped
+    // collection.
+    assert.writeError(localDB.oplog.rs.insert({}));
+
+    // Test that inserting into the master-slave oplog fails when implicitly creating a non-capped
+    // collection.
+    assert.commandFailed(localDB.runCommand({godinsert: 'oplog.$main', obj: {}}));
+
+    // Test that creating a non-capped oplog collection fails when using $out.
+    assert.writeOK(localDB.input.insert({}));
+    assert.commandFailed(localDB.runCommand({
+        aggregate: 'input',
+        pipeline: [{$out: 'oplog.aggregation'}],
+    }));
+
+    MongoRunner.stopMongod(conn);
+})();
diff --git a/src/mongo/db/catalog/database.cpp b/src/mongo/db/catalog/database.cpp
index 23775d859c4..0d6f0e9aef2 100644
--- a/src/mongo/db/catalog/database.cpp
+++ b/src/mongo/db/catalog/database.cpp
@@ -487,6 +487,7 @@ Collection* Database::createCollection(OperationContext* txn,
 
     NamespaceString nss(ns);
     uassert(17316, "cannot create a blank collection", nss.coll() > 0);
+    uassert(28838, "cannot create a non-capped oplog collection", options.capped || !nss.isOplog());
 
     audit::logCreateCollection(currentClient.get(), ns);