Put app shim IPC socket in a temporary directory. (Mac)

chrome/common/mac/app_mode_common.mm

 // Copyright (c) 2012 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 "chrome/common/mac/app_mode_common.h"
 
+#include "base/file_util.h"
+
 namespace app_mode {
 
 const char kAppShimSocketName[] = "App Shim Socket";
 
 const char kAppListModeId[] = "app_list";
 
 const char kLaunchedByChromeProcessId[] = "launched-by-chrome-process-id";
 
 NSString* const kCFBundleDisplayNameKey = @"CFBundleDisplayName";
 NSString* const kLSHasLocalizedDisplayNameKey = @"LSHasLocalizedDisplayName";
@@ skipping 16 matching lines @@
 ChromeAppModeInfo::ChromeAppModeInfo()
     : major_version(0),
       minor_version(0),
       argc(0),
       argv(0) {
 }
 
 ChromeAppModeInfo::~ChromeAppModeInfo() {
 }
 
+void VerifySocketPermissions(const base::FilePath& socket_path) {
+  CHECK(base::PathIsWritable(socket_path));
+  int socket_mode = 0;
+  CHECK(base::GetPosixFilePermissions(socket_path, &socket_mode));
+  int socket_permissions =
+      base::FILE_PERMISSION_MASK &
+      ~(base::FILE_PERMISSION_WRITE_BY_GROUP) &
+      ~(base::FILE_PERMISSION_WRITE_BY_OTHERS);

[tapted, 2014/01/03 13:06:54]

ugh - why does this enum exist.. The comment says "Bits ans [sic] masks of the
file permission". I'd find CHECK_EQ(0755, socket_mode) a lot more readable -
maybe I'm just old school :p. But also, are we sure this is guaranteed? If you
run `umask 0007` from Terminal, then run Chrome with the full path to the binary
in the app bundle, will it fail? -- inheriting that umask might make the mode
0750 instead.

[jackhou1, 2014/01/06 05:29:52]

Done.

Also you're right, the sockets permissions depend on umask. However, the
directory is always created with 0700. Would we need to set the mode of the
socket explicitly?

[tapted, 2014/01/06 07:31:28]

I don't think we need to set the socket inode permissions separately (parent
folder in mode 0700 should be sufficient), but the security folks will know
better.

+  CHECK_EQ(socket_permissions, socket_mode);
+  base::FilePath socket_dir = socket_path.DirName();
+  int socket_dir_mode = 0;
+  CHECK(base::GetPosixFilePermissions(socket_dir, &socket_dir_mode));
+  CHECK_EQ(base::FILE_PERMISSION_USER_MASK, socket_dir_mode);
+}
+
 }  // namespace app_mode