sandbox/linux/suid/client/setuid_sandbox_client.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef SANDBOX_LINUX_SUID_SETUID_SANDBOX_CLIENT_H_
   6 #define SANDBOX_LINUX_SUID_SETUID_SANDBOX_CLIENT_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/callback_forward.h"
  10 #include "base/files/file_path.h"
  11 #include "base/files/scoped_file.h"
  12 #include "base/process/launch.h"
  13 #include "sandbox/sandbox_export.h"
  14
  15 namespace sandbox {
  16
  17 // Helper class to use the setuid sandbox. This class is to be used both
  18 // before launching the setuid helper and after being executed through the
  19 // setuid helper.
  20 // This class is difficult to use. It has been created by refactoring very old
  21 // code scathered through the Chromium code base.
  22 //
  23 // A typical use for "A" launching a sandboxed process "B" would be:
  24 // 1. A calls SetupLaunchEnvironment()
  25 // 2. A sets up a CommandLine and then amends it with
  26 //    PrependWrapper() (or manually, by relying on GetSandboxBinaryPath()).
  27 // 3. A uses SetupLaunchOptions() to arrange for a dummy descriptor for the
  28 //    setuid sandbox ABI.
  29 // 4. A launches B with base::LaunchProcess, using the amended CommandLine.
  30 // 5. B uses CloseDummyFile() to close the dummy file descriptor.
  31 // 6. B performs various initializations that require access to the file
  32 //    system.
  33 // 6.b (optional) B uses sandbox::Credentials::HasOpenDirectory() to verify
  34 //    that no directory is kept open (which would allow bypassing the setuid
  35 //    sandbox).
  36 // 7. B should be prepared to assume the role of init(1). In particular, B
  37 //    cannot receive any signal from any other process, excluding SIGKILL.
  38 //    If B dies, all the processes in the namespace will die.
  39 //    B can fork() and the parent can assume the role of init(1), by using
  40 //    CreateInitProcessReaper().
  41 // 8. B requests being chroot-ed through ChrootMe() and
  42 //    requests other sandboxing status via the status functions.
  43 class SANDBOX_EXPORT SetuidSandboxClient {
  44  public:
  45   // All instantation should go through this factory method.
  46   static class SetuidSandboxClient* Create();
  47   ~SetuidSandboxClient();
  48
  49   // Close the dummy file descriptor leftover from the sandbox ABI.
  50   void CloseDummyFile();
  51   // Ask the setuid helper over the setuid sandbox IPC channel to chroot() us
  52   // to an empty directory.
  53   // Will only work if we have been launched through the setuid helper.
  54   bool ChrootMe();
  55   // When a new PID namespace is created, the process with pid == 1 should
  56   // assume the role of init.
  57   // See sandbox/linux/services/init_process_reaper.h for more information
  58   // on this API.
  59   bool CreateInitProcessReaper(base::Closure* post_fork_parent_callback);
  60
  61   // Did we get launched through an up to date setuid binary ?
  62   bool IsSuidSandboxUpToDate() const;
  63   // Did we get launched through the setuid helper ?
  64   bool IsSuidSandboxChild() const;
  65   // Did the setuid helper create a new PID namespace ?
  66   bool IsInNewPIDNamespace() const;
  67   // Did the setuid helper create a new network namespace ?
  68   bool IsInNewNETNamespace() const;
  69   // Are we done and fully sandboxed ?
  70   bool IsSandboxed() const;
  71
  72   // The setuid sandbox may still be disabled via the environment.
  73   // This is tracked in crbug.com/245376.
  74   bool IsDisabledViaEnvironment();
  75   // Get the sandbox binary path. This method knows about the
  76   // CHROME_DEVEL_SANDBOX environment variable used for user-managed builds. If
  77   // the sandbox binary cannot be found, it will return an empty FilePath.
  78   base::FilePath GetSandboxBinaryPath();
  79   // Modify |cmd_line| to launch via the setuid sandbox. Crash if the setuid
  80   // sandbox binary cannot be found.  |cmd_line| must not be NULL.
  81   void PrependWrapper(base::CommandLine* cmd_line);
  82   // Set-up the launch options for launching via the setuid sandbox.  Caller is
  83   // responsible for keeping |dummy_fd| alive until LaunchProcess() completes.
  84   // |options| and |fds_to_remap| must not be NULL.
  85   // (Keeping |dummy_fd| alive is an unfortunate historical artifact of the
  86   // chrome-sandbox ABI.)
  87   void SetupLaunchOptions(base::LaunchOptions* options,
  88                           base::FileHandleMappingVector* fds_to_remap,
  89                           base::ScopedFD* dummy_fd);
  90   // Set-up the environment. This should be done prior to launching the setuid
  91   // helper.
  92   void SetupLaunchEnvironment();
  93
  94  private:
  95   SetuidSandboxClient();
  96
  97   // Holds the environment. Will never be NULL.
  98   base::Environment* env_;
  99   bool sandboxed_;
 100
 101   DISALLOW_COPY_AND_ASSIGN(SetuidSandboxClient);
 102 };
 103
 104 }  // namespace sandbox
 105
 106 #endif  // SANDBOX_LINUX_SUID_SETUID_SANDBOX_CLIENT_H_