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_SERVICES_BROKER_PROCESS_H_
  #define SANDBOX_LINUX_SERVICES_BROKER_PROCESS_H_
  
  #include <string>
  #include <vector>
  
  #include "base/basictypes.h"
  #include "base/pickle.h"
  #include "base/process.h"
  
  namespace sandbox {
  
  // Create a new "broker" process to which we can send requests via an IPC
  // channel.
  // This is a low level IPC mechanism that is suitable to be called from a
  // signal handler.
  // A process would typically create a broker process before entering
  // sandboxing.
  // 1. BrokerProcess open_broker(read_whitelist, write_whitelist);
  // 2. CHECK(open_broker.Init(NULL));
  // 3. Enable sandbox.
  // 4. Use open_broker.Open() to open files.
  class BrokerProcess {
   public:
    // |allowed_file_names| is a white list of files that can be opened later via
    // the Open() API.
    // |fast_check_in_client| and |quiet_failures_for_tests| are reserved for
    // unit tests, don't use it.
    explicit BrokerProcess(const std::vector<std::string>& allowed_r_files_,
                           const std::vector<std::string>& allowed_w_files_,
                           bool fast_check_in_client = true,
                           bool quiet_failures_for_tests = false);
    ~BrokerProcess();
    // Will initialize the broker process. There should be no threads at this
    // point, since we need to fork().
    // sandbox_callback is a function that should be called to enable the
    // sandbox in the broker.
    bool Init(bool (*sandbox_callback)(void));
  
    // Can be used in place of access(). Will be async signal safe.
    // X_OK will always EPERM in practice since the broker process doesn't support
    // execute permissions.
    // It's similar to the access() system call and will return -errno on errors.
    int Access(const char* pathname, int mode) const;
    // Can be used in place of open(). Will be async signal safe.
    // The implementation only supports certain white listed flags and will
    // return -EPERM on other flags.
    // It's similar to the open() system call and will return -errno on errors.
    int Open(const char* pathname, int flags) const;
  
    int broker_pid() const { return broker_pid_; }
  
   private:
    enum IPCCommands {
      kCommandInvalid = 0,
      kCommandOpen,
      kCommandAccess,
    };
    int PathAndFlagsSyscall(enum IPCCommands command_type,
                            const char* pathname, int flags) const;
    bool HandleRequest() const;
    bool HandleRemoteCommand(IPCCommands command_type, int reply_ipc,
        const Pickle& read_pickle, PickleIterator iter) const;
  
    void AccessFileForIPC(const std::string& requested_filename,
                          int mode, Pickle* write_pickle) const;
    void OpenFileForIPC(const std::string& requested_filename,
                        int flags, Pickle* write_pickle,
                        std::vector<int>* opened_files) const;
    bool GetFileNameIfAllowedToAccess(const char*, int, const char**) const;
    bool GetFileNameIfAllowedToOpen(const char*, int, const char**) const;
    bool initialized_;  // Whether we've been through Init() yet.
    bool is_child_;  // Whether we're the child (broker process).
    bool fast_check_in_client_;  // Whether to forward a request that we know
                                 // will be denied to the broker.
    bool quiet_failures_for_tests_;  // Disable certain error message when
                                     // testing for failures.
    pid_t broker_pid_;  // The PID of the broker (child).
    const std::vector<std::string> allowed_r_files_;  // Files allowed for read.
    const std::vector<std::string> allowed_w_files_;  // Files allowed for write.
    int ipc_socketpair_;  // Our communication channel to parent or child.
    DISALLOW_IMPLICIT_CONSTRUCTORS(BrokerProcess);
  };
  
  }  // namespace sandbox
  
  #endif  // SANDBOX_LINUX_SERVICES_BROKER_PROCESS_H_
  