text: // 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_
  
  #include <memory>
  
  #include "base/environment.h"
  #include "base/macros.h"
  #include "sandbox/sandbox_export.h"
  
  namespace sandbox {
  
  // Helper class to use the setuid sandbox. This class is to be used
  // after being executed through 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:
  // (Steps 1 through 4 are described in setuid_sandbox_host.h.)
  // 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
  //    sandbox::CreateInitProcessReaper().
  // 8. B requests being chroot-ed through ChrootMe() and
  //    requests other sandboxing status via the status functions.
  class SANDBOX_EXPORT SetuidSandboxClient {
   public:
    // All instantation should go through this factory method.
    static 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;
  
   private:
    explicit SetuidSandboxClient(base::Environment* env);
  
    // Holds the environment. Will never be NULL.
    std::unique_ptr<base::Environment> env_;
    bool sandboxed_;
  
    DISALLOW_COPY_AND_ASSIGN(SetuidSandboxClient);
  };
  
  }  // namespace sandbox
  
  #endif  // SANDBOX_LINUX_SUID_SETUID_SANDBOX_CLIENT_H_
  