sandbox/linux/services/broker_process.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_SERVICES_BROKER_PROCESS_H_
   6 #define SANDBOX_LINUX_SERVICES_BROKER_PROCESS_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/basictypes.h"
  12 #include "base/pickle.h"
  13 #include "base/process/process.h"
  14
  15 namespace sandbox {
  16
  17 // Create a new "broker" process to which we can send requests via an IPC
  18 // channel.
  19 // This is a low level IPC mechanism that is suitable to be called from a
  20 // signal handler.
  21 // A process would typically create a broker process before entering
  22 // sandboxing.
  23 // 1. BrokerProcess open_broker(read_whitelist, write_whitelist);
  24 // 2. CHECK(open_broker.Init(NULL));
  25 // 3. Enable sandbox.
  26 // 4. Use open_broker.Open() to open files.
  27 class BrokerProcess {
  28  public:
  29   // |allowed_file_names| is a white list of files that can be opened later via
  30   // the Open() API.
  31   // |fast_check_in_client| and |quiet_failures_for_tests| are reserved for
  32   // unit tests, don't use it.
  33   explicit BrokerProcess(const std::vector<std::string>& allowed_r_files_,
  34                          const std::vector<std::string>& allowed_w_files_,
  35                          bool fast_check_in_client = true,
  36                          bool quiet_failures_for_tests = false);
  37   ~BrokerProcess();
  38   // Will initialize the broker process. There should be no threads at this
  39   // point, since we need to fork().
  40   // sandbox_callback is a function that should be called to enable the
  41   // sandbox in the broker.
  42   bool Init(bool (*sandbox_callback)(void));
  43
  44   // Can be used in place of access(). Will be async signal safe.
  45   // X_OK will always EPERM in practice since the broker process doesn't support
  46   // execute permissions.
  47   // It's similar to the access() system call and will return -errno on errors.
  48   int Access(const char* pathname, int mode) const;
  49   // Can be used in place of open(). Will be async signal safe.
  50   // The implementation only supports certain white listed flags and will
  51   // return -EPERM on other flags.
  52   // It's similar to the open() system call and will return -errno on errors.
  53   int Open(const char* pathname, int flags) const;
  54
  55   int broker_pid() const { return broker_pid_; }
  56
  57  private:
  58   enum IPCCommands {
  59     kCommandInvalid = 0,
  60     kCommandOpen,
  61     kCommandAccess,
  62   };
  63   int PathAndFlagsSyscall(enum IPCCommands command_type,
  64                           const char* pathname, int flags) const;
  65   bool HandleRequest() const;
  66   bool HandleRemoteCommand(IPCCommands command_type, int reply_ipc,
  67       const Pickle& read_pickle, PickleIterator iter) const;
  68
  69   void AccessFileForIPC(const std::string& requested_filename,
  70                         int mode, Pickle* write_pickle) const;
  71   void OpenFileForIPC(const std::string& requested_filename,
  72                       int flags, Pickle* write_pickle,
  73                       std::vector<int>* opened_files) const;
  74   bool GetFileNameIfAllowedToAccess(const char*, int, const char**) const;
  75   bool GetFileNameIfAllowedToOpen(const char*, int, const char**) const;
  76   bool initialized_;  // Whether we've been through Init() yet.
  77   bool is_child_;  // Whether we're the child (broker process).
  78   bool fast_check_in_client_;  // Whether to forward a request that we know
  79                                // will be denied to the broker.
  80   bool quiet_failures_for_tests_;  // Disable certain error message when
  81                                    // testing for failures.
  82   pid_t broker_pid_;  // The PID of the broker (child).
  83   const std::vector<std::string> allowed_r_files_;  // Files allowed for read.
  84   const std::vector<std::string> allowed_w_files_;  // Files allowed for write.
  85   int ipc_socketpair_;  // Our communication channel to parent or child.
  86   DISALLOW_IMPLICIT_CONSTRUCTORS(BrokerProcess);
  87 };
  88
  89 }  // namespace sandbox
  90
  91 #endif  // SANDBOX_LINUX_SERVICES_BROKER_PROCESS_H_