handler/mac: Log a warning when an exception message has a suspicious

util/mach/mach_message_test.cc

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
 #include "util/mach/mach_message.h"
 
+#include <unistd.h>
+
 #include "base/basictypes.h"
+#include "base/mac/scoped_mach_port.h"
 #include "gtest/gtest.h"
 #include "util/mach/mach_extensions.h"
+#include "util/test/mac/mach_errors.h"
 
 namespace crashpad {
 namespace test {
 namespace {
 
 TEST(MachMessage, MachMessageDeadlineFromTimeout) {
   MachMessageDeadline deadline_0 =
       MachMessageDeadlineFromTimeout(kMachMessageTimeoutNonblocking);
   EXPECT_EQ(kMachMessageDeadlineNonblocking, deadline_0);
 
@@ skipping 67 matching lines @@
   union TestMessage {
     TestSendMessage send;
     TestReceiveMessage receive;
   };
 
   TestMessage test;
   test.send.msgh_size = sizeof(TestSendMessage);
   EXPECT_EQ(&test.receive.trailer, MachMessageTrailerFromHeader(&test.receive));
 }
 
+TEST(MachMessage, AuditPIDFromMachMessageTrailer) {
+  base::mac::ScopedMachReceiveRight port(NewMachPort(MACH_PORT_RIGHT_RECEIVE));
+  ASSERT_NE(kMachPortNull, port);
+
+  mach_msg_empty_send_t send = {};
+  send.header.msgh_bits = MACH_MSGH_BITS(MACH_MSG_TYPE_MAKE_SEND_ONCE, 0);
+  send.header.msgh_size = sizeof(send);
+  send.header.msgh_remote_port = port;
+  mach_msg_return_t mr =
+      MachMessageWithDeadline(&send.header,
+                              MACH_SEND_MSG,
+                              0,
+                              MACH_PORT_NULL,
+                              kMachMessageDeadlineNonblocking,
+                              MACH_PORT_NULL,
+                              false);
+  ASSERT_EQ(MACH_MSG_SUCCESS, mr)
+      << MachErrorMessage(mr, "MachMessageWithDeadline send");
+
+  struct EmptyReceiveMessageWithAuditTrailer : public mach_msg_empty_send_t {
+    union {
+      mach_msg_trailer_t trailer;
+      mach_msg_audit_trailer_t audit_trailer;
+    };
+  };
+
+  EmptyReceiveMessageWithAuditTrailer receive;
+  mr = MachMessageWithDeadline(&receive.header,
+                               MACH_RCV_MSG | kMachMessageReceiveAuditTrailer,
+                               sizeof(receive),
+                               port,
+                               kMachMessageDeadlineNonblocking,
+                               MACH_PORT_NULL,
+                               false);
+  ASSERT_EQ(MACH_MSG_SUCCESS, mr)
+      << MachErrorMessage(mr, "MachMessageWithDeadline receive");
+
+  EXPECT_EQ(getpid(), AuditPIDFromMachMessageTrailer(&receive.trailer));
+}
+
 }  // namespace
 }  // namespace test
 }  // namespace crashpad