sandbox: extract SetuidSandboxHost code from SetuidSandboxClient

sandbox/linux/suid/client/setuid_sandbox_host.h

 // 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.
 
-#ifndef SANDBOX_LINUX_SUID_SETUID_SANDBOX_CLIENT_H_
-#define SANDBOX_LINUX_SUID_SETUID_SANDBOX_CLIENT_H_
+#ifndef SANDBOX_LINUX_SUID_SETUID_SANDBOX_HOST_H_
+#define SANDBOX_LINUX_SUID_SETUID_SANDBOX_HOST_H_
 
 #include "base/basictypes.h"
-#include "base/command_line.h"
-#include "base/environment.h"
 #include "base/files/file_path.h"
 #include "base/files/scoped_file.h"
 #include "base/process/launch.h"
 #include "sandbox/sandbox_export.h"
 
 namespace sandbox {
 
-// Helper class to use the setuid sandbox. This class is to be used both
-// before launching the setuid helper and after being executed through the
-// setuid helper.
+// Helper class to use the setuid sandbox. This class is to be used
+// before launching the setuid helper.
 // This class is difficult to use. It has been created by refactoring very old
 // code scathered through the Chromium code base.
 //
 // A typical use for "A" launching a sandboxed process "B" would be:
 // 1. A calls SetupLaunchEnvironment()
 // 2. A sets up a CommandLine and then amends it with
 //    PrependWrapper() (or manually, by relying on GetSandboxBinaryPath()).
 // 3. A uses SetupLaunchOptions() to arrange for a dummy descriptor for the
 //    setuid sandbox ABI.
 // 4. A launches B with base::LaunchProcess, using the amended CommandLine.
-// 5. B uses CloseDummyFile() to close the dummy file descriptor.
-// 6. B performs various initializations that require access to the file
-//    system.
-// 6.b (optional) B uses sandbox::Credentials::HasOpenDirectory() to verify
-//    that no directory is kept open (which would allow bypassing the setuid
-//    sandbox).
-// 7. B should be prepared to assume the role of init(1). In particular, B
-//    cannot receive any signal from any other process, excluding SIGKILL.
-//    If B dies, all the processes in the namespace will die.
-//    B can fork() and the parent can assume the role of init(1), by using
-//    CreateInitProcessReaper().
-// 8. B requests being chroot-ed through ChrootMe() and
-//    requests other sandboxing status via the status functions.
-class SANDBOX_EXPORT SetuidSandboxClient {
+// (The remaining steps are described within SetuidSandboxClient.)

[rickyz (no longer on Chrome), 2015/02/04 10:46:00]

nit: The comment in setuid_sandbox_host.h points the reader at the filename
instead of the class name

[mdempsky, 2015/02/04 10:53:29]

Done: both now use file name.

+class SANDBOX_EXPORT SetuidSandboxHost {
  public:
   // All instantation should go through this factory method.
-  static class SetuidSandboxClient* Create();
-  ~SetuidSandboxClient();
-
-  // Close the dummy file descriptor leftover from the sandbox ABI.
-  void CloseDummyFile();
-  // Ask the setuid helper over the setuid sandbox IPC channel to chroot() us
-  // to an empty directory.
-  // Will only work if we have been launched through the setuid helper.
-  bool ChrootMe();
-
-  // Did we get launched through an up to date setuid binary ?
-  bool IsSuidSandboxUpToDate() const;
-  // Did we get launched through the setuid helper ?
-  bool IsSuidSandboxChild() const;
-  // Did the setuid helper create a new PID namespace ?
-  bool IsInNewPIDNamespace() const;
-  // Did the setuid helper create a new network namespace ?
-  bool IsInNewNETNamespace() const;
-  // Are we done and fully sandboxed ?
-  bool IsSandboxed() const;
+  static class SetuidSandboxHost* Create();

[rickyz (no longer on Chrome), 2015/02/04 10:46:00]

nit: Remove the class

[mdempsky, 2015/02/04 10:53:29]

Done.

+  ~SetuidSandboxHost();
 
   // The setuid sandbox may still be disabled via the environment.
   // This is tracked in crbug.com/245376.
   bool IsDisabledViaEnvironment();
   // Get the sandbox binary path. This method knows about the
   // CHROME_DEVEL_SANDBOX environment variable used for user-managed builds. If
   // the sandbox binary cannot be found, it will return an empty FilePath.
   base::FilePath GetSandboxBinaryPath();
   // Modify |cmd_line| to launch via the setuid sandbox. Crash if the setuid
   // sandbox binary cannot be found.  |cmd_line| must not be NULL.
   void PrependWrapper(base::CommandLine* cmd_line);
   // Set-up the launch options for launching via the setuid sandbox.  Caller is
   // responsible for keeping |dummy_fd| alive until LaunchProcess() completes.
   // |options| and |fds_to_remap| must not be NULL.
   // (Keeping |dummy_fd| alive is an unfortunate historical artifact of the
   // chrome-sandbox ABI.)
   void SetupLaunchOptions(base::LaunchOptions* options,
                           base::FileHandleMappingVector* fds_to_remap,
                           base::ScopedFD* dummy_fd);
   // Set-up the environment. This should be done prior to launching the setuid
   // helper.
   void SetupLaunchEnvironment();
 
  private:
-  SetuidSandboxClient();
+  SetuidSandboxHost();
 
   // Holds the environment. Will never be NULL.
   base::Environment* env_;
-  bool sandboxed_;
 
-  DISALLOW_COPY_AND_ASSIGN(SetuidSandboxClient);
+  DISALLOW_COPY_AND_ASSIGN(SetuidSandboxHost);
 };
 
 }  // namespace sandbox
 
-#endif  // SANDBOX_LINUX_SUID_SETUID_SANDBOX_CLIENT_H_
+#endif  // SANDBOX_LINUX_SUID_SETUID_SANDBOX_HOST_H_