SERVER-14128 Disallow requests for non-unique _id indexes

3 files changed, 53 insertions, 7 deletions

diff --git a/jstests/core/index_id_unique.js b/jstests/core/index_id_unique.js
new file mode 100644
index 00000000000..ba0a22db47f
--- /dev/null
+++ b/jstests/core/index_id_unique.js
@@ -0,0 +1,25 @@
+// Test creation of the _id index with various values for the "unique" option.
+
+var coll = db.index_id_unique;
+
+// Creation of _id index with "non-zero" value for "unique" should succeed.
+coll.drop();
+assert.commandWorked(coll.runCommand("create", {autoIndexId: false}));
+assert.commandWorked(coll.ensureIndex({_id: 1}, {unique: true}));
+coll.drop();
+assert.commandWorked(coll.runCommand("create", {autoIndexId: false}));
+assert.commandWorked(coll.ensureIndex({_id: 1}, {unique: 1}));
+coll.drop();
+assert.commandWorked(coll.runCommand("create", {autoIndexId: false}));
+assert.commandWorked(coll.ensureIndex({_id: 1}, {unique: NumberLong(1)}));
+
+// Creation of _id index with "zero" value for "unique" should fail.
+coll.drop();
+assert.commandWorked(coll.runCommand("create", {autoIndexId: false}));
+assert.commandFailed(coll.ensureIndex({_id: 1}, {unique: false}));
+coll.drop();
+assert.commandWorked(coll.runCommand("create", {autoIndexId: false}));
+assert.commandFailed(coll.ensureIndex({_id: 1}, {unique: 0}));
+coll.drop();
+assert.commandWorked(coll.runCommand("create", {autoIndexId: false}));
+assert.commandFailed(coll.ensureIndex({_id: 1}, {unique: NumberLong(0)}));
diff --git a/src/mongo/db/catalog/index_catalog.cpp b/src/mongo/db/catalog/index_catalog.cpp
index b8567599410..77b68682877 100644
--- a/src/mongo/db/catalog/index_catalog.cpp
+++ b/src/mongo/db/catalog/index_catalog.cpp
@@ -462,6 +462,21 @@ namespace {
 
         const NamespaceString& nss = _collection->ns();
 
+        BSONElement vElt = spec["v"];
+        if( !vElt.eoo() ) {
+            if ( !vElt.isNumber() ) {
+                return Status( ErrorCodes::CannotCreateIndex,
+                               str::stream() << "non-numeric value for \"v\" field:" << vElt );
+            }
+            double v = vElt.Number();
+            // note (one day) we may be able to fresh build less versions than we can use
+            // isASupportedIndexVersionNumber() is what we can use
+            if ( v != 0 && v != 1 ) {
+                return Status( ErrorCodes::CannotCreateIndex,
+                               str::stream() << "this version of mongod cannot build new indexes "
+                                             << "of version number " << v );
+            }
+        }
 
         if ( nss.isSystemDotIndexes() )
             return Status( ErrorCodes::CannotCreateIndex,
@@ -511,7 +526,13 @@ namespace {
                                          << "not allow document removal." );
         }
 
-        if ( !IndexDescriptor::isIdIndexPattern( key ) ) {
+        if ( IndexDescriptor::isIdIndexPattern( key ) ) {
+            BSONElement uniqueElt = spec["unique"];
+            if ( !uniqueElt.eoo() && !uniqueElt.trueValue() ) {
+                return Status( ErrorCodes::CannotCreateIndex, "_id index cannot be non-unique" );
+            }
+        }
+        else {
             // for non _id indexes, we check to see if replication has turned off all indexes
             // we _always_ created _id index
             repl::ReplicationCoordinator* replCoord = repl::getGlobalReplicationCoordinator();
@@ -1085,13 +1106,9 @@ namespace {
 
         int v = DefaultIndexVersionNumber;
         if( !o["v"].eoo() ) {
-            double vv = o["v"].Number();
-            // note (one day) we may be able to fresh build less versions than we can use
-            // isASupportedIndexVersionNumber() is what we can use
-            uassert(14803, str::stream() << "this version of mongod cannot build new indexes of version number " << vv, 
-                    vv == 0 || vv == 1);
-            v = (int) vv;
+            v = o["v"].numberInt();
         }
+
         // idea is to put things we use a lot earlier
         b.append("v", v);
 
diff --git a/src/mongo/db/catalog/index_catalog.h b/src/mongo/db/catalog/index_catalog.h
index a541a8bae0a..2f4ed0b677e 100644
--- a/src/mongo/db/catalog/index_catalog.h
+++ b/src/mongo/db/catalog/index_catalog.h
@@ -306,6 +306,10 @@ namespace mongo {
         IndexCatalogEntry* _setupInMemoryStructures(OperationContext* txn,
                                                     IndexDescriptor* descriptor );
 
+        // Apply a set of transformations to the user-provided index object 'spec' to make it
+        // conform to the standard for insertion.  This function adds the 'v' field if it didn't
+        // exist, removes the '_id' field if it exists, applies plugin-level transformations if
+        // appropriate, etc.
         static BSONObj _fixIndexSpec( const BSONObj& spec );
 
         Status _isSpecOk( const BSONObj& spec ) const;