Alter the design of the bootstrap sandbox to only take over the bootstrap port of children when nec…

sandbox/mac/mach_message_server.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sandbox/mac/mach_message_server.h"
 
 #include <bsm/libbsm.h>
 #include <servers/bootstrap.h>
 
 #include <string>
 
 #include "base/logging.h"
 #include "base/mac/mach_logging.h"
 #include "base/strings/stringprintf.h"
 
 namespace sandbox {
 
 MachMessageServer::MachMessageServer(
     MessageDemuxer* demuxer,
+    mach_port_t server_receive_right,
     mach_msg_size_t buffer_size)
     : demuxer_(demuxer),
-      server_port_(MACH_PORT_NULL),
+      server_port_(server_receive_right),
       server_queue_(NULL),
       server_source_(NULL),
       buffer_size_(
           mach_vm_round_page(buffer_size + sizeof(mach_msg_audit_trailer_t))),
       did_forward_message_(false) {
   DCHECK(demuxer_);
 }
 
 MachMessageServer::~MachMessageServer() {
   if (server_source_)
     dispatch_release(server_source_);
   if (server_queue_)
     dispatch_release(server_queue_);
 }
 
 bool MachMessageServer::Initialize() {
   mach_port_t task = mach_task_self();
   kern_return_t kr;
 
-  // Allocate a port for use as a new server port.
-  mach_port_t port;
-  if ((kr = mach_port_allocate(task, MACH_PORT_RIGHT_RECEIVE, &port)) !=
-          KERN_SUCCESS) {
-    MACH_LOG(ERROR, kr) << "Failed to allocate new server port.";
-    return false;
+  // Allocate a port for use as a new server port if one was not passed to the
+  // constructor.
+  if (!server_port_.is_valid()) {
+    mach_port_t port;
+    if ((kr = mach_port_allocate(task, MACH_PORT_RIGHT_RECEIVE, &port)) !=
+            KERN_SUCCESS) {
+      MACH_LOG(ERROR, kr) << "Failed to allocate new server port.";
+      return false;
+    }
+    server_port_.reset(port);
   }
-  server_port_.reset(port);
 
   // Allocate the message request and reply buffers.
   const int kMachMsgMemoryFlags = VM_MAKE_TAG(VM_MEMORY_MACH_MSG) |
                                   VM_FLAGS_ANYWHERE;
   vm_address_t buffer = 0;
 
   kr = vm_allocate(task, &buffer, buffer_size_, kMachMsgMemoryFlags);
   if (kr != KERN_SUCCESS) {
     MACH_LOG(ERROR, kr) << "Failed to allocate request buffer.";
     return false;
@@ skipping 111 matching lines @@
   // forwarded message was sent from the process hosting this sandbox server,
   // destroying the message could also destroy rights held outside the scope of
   // this message server.
   if (!did_forward_message_) {
     mach_msg_destroy(request);
     mach_msg_destroy(reply);
   }
 }
 
 }  // namespace sandbox