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/callback_forward.h"
  13 #include "base/pickle.h"
  14 #include "base/process/process.h"
  15 #include "sandbox/sandbox_export.h"
  16
  17 namespace sandbox {
  18
  19 // Create a new "broker" process to which we can send requests via an IPC
  20 // channel.
  21 // This is a low level IPC mechanism that is suitable to be called from a
  22 // signal handler.
  23 // A process would typically create a broker process before entering
  24 // sandboxing.
  25 // 1. BrokerProcess open_broker(read_whitelist, write_whitelist);
  26 // 2. CHECK(open_broker.Init(NULL));
  27 // 3. Enable sandbox.
  28 // 4. Use open_broker.Open() to open files.
  29 class SANDBOX_EXPORT BrokerProcess {
  30  public:
  31   // |denied_errno| is the error code returned when methods such as Open()
  32   // or Access() are invoked on a file which is not in the whitelist. EACCESS
  33   // would be a typical value.
  34   // |allowed_r_files| and |allowed_w_files| are white lists of files that can
  35   // be opened later via the Open() API, respectively for reading and writing.
  36   // A file available read-write should be listed in both.
  37   // |fast_check_in_client| and |quiet_failures_for_tests| are reserved for
  38   // unit tests, don't use it.
  39   explicit BrokerProcess(int denied_errno,
  40                          const std::vector<std::string>& allowed_r_files,
  41                          const std::vector<std::string>& allowed_w_files,
  42                          bool fast_check_in_client = true,
  43                          bool quiet_failures_for_tests = false);
  44   ~BrokerProcess();
  45   // Will initialize the broker process. There should be no threads at this
  46   // point, since we need to fork().
  47   // broker_process_init_callback will be called in the new broker process,
  48   // after fork() returns.
  49   bool Init(const base::Callback<bool(void)>& broker_process_init_callback);
  50
  51   // Can be used in place of access(). Will be async signal safe.
  52   // X_OK will always return an error in practice since the broker process
  53   // doesn't support execute permissions.
  54   // It's similar to the access() system call and will return -errno on errors.
  55   int Access(const char* pathname, int mode) const;
  56   // Can be used in place of open(). Will be async signal safe.
  57   // The implementation only supports certain white listed flags and will
  58   // return -EPERM on other flags.
  59   // It's similar to the open() system call and will return -errno on errors.
  60   int Open(const char* pathname, int flags) const;
  61
  62   int broker_pid() const { return broker_pid_; }
  63
  64  private:
  65   enum IPCCommands {
  66     kCommandInvalid = 0,
  67     kCommandOpen,
  68     kCommandAccess,
  69   };
  70   int PathAndFlagsSyscall(enum IPCCommands command_type,
  71                           const char* pathname,
  72                           int flags) const;
  73   bool HandleRequest() const;
  74   bool HandleRemoteCommand(IPCCommands command_type,
  75                            int reply_ipc,
  76                            const Pickle& read_pickle,
  77                            PickleIterator iter) const;
  78
  79   void AccessFileForIPC(const std::string& requested_filename,
  80                         int mode,
  81                         Pickle* write_pickle) const;
  82   void OpenFileForIPC(const std::string& requested_filename,
  83                       int flags,
  84                       Pickle* write_pickle,
  85                       std::vector<int>* opened_files) const;
  86   bool GetFileNameIfAllowedToAccess(const char*, int, const char**) const;
  87   bool GetFileNameIfAllowedToOpen(const char*, int, const char**) const;
  88   const int denied_errno_;
  89   bool initialized_;               // Whether we've been through Init() yet.
  90   bool is_child_;                  // Whether we're the child (broker process).
  91   bool fast_check_in_client_;      // Whether to forward a request that we know
  92                                    // will be denied to the broker.
  93   bool quiet_failures_for_tests_;  // Disable certain error message when
  94                                    // testing for failures.
  95   pid_t broker_pid_;               // The PID of the broker (child).
  96   const std::vector<std::string> allowed_r_files_;  // Files allowed for read.
  97   const std::vector<std::string> allowed_w_files_;  // Files allowed for write.
  98   int ipc_socketpair_;  // Our communication channel to parent or child.
  99   DISALLOW_IMPLICIT_CONSTRUCTORS(BrokerProcess);
 100
 101   friend class BrokerProcessTestHelper;
 102 };
 103
 104 }  // namespace sandbox
 105
 106 #endif  // SANDBOX_LINUX_SERVICES_BROKER_PROCESS_H_