Move Windows Sandbox, trybots version (don't commit me!)

sandbox/src/crosscall_params.h

-// 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_SRC_CROSSCALL_PARAMS_H__
-#define SANDBOX_SRC_CROSSCALL_PARAMS_H__
-
-#include <windows.h>
-#include <lmaccess.h>
-
-#include <memory>
-
-#include "base/basictypes.h"
-#include "sandbox/src/internal_types.h"
-#include "sandbox/src/sandbox_types.h"
-
-namespace {
-
-// Increases |value| until there is no need for padding given an int64
-// alignment. Returns the increased value.
-uint32 Align(uint32 value) {
-  uint32 alignment = sizeof(int64);
-  return ((value + alignment - 1) / alignment) * alignment;
-}
-
-}
-// This header is part of CrossCall: the sandbox inter-process communication.
-// This header defines the basic types used both in the client IPC and in the
-// server IPC code. CrossCallParams and ActualCallParams model the input
-// parameters of an IPC call and CrossCallReturn models the output params and
-// the return value.
-//
-// An IPC call is defined by its 'tag' which is a (uint32) unique identifier
-// that is used to route the IPC call to the proper server. Every tag implies
-// a complete call signature including the order and type of each parameter.
-//
-// Like most IPC systems. CrossCall is designed to take as inputs 'simple'
-// types such as integers and strings. Classes, generic arrays or pointers to
-// them are not supported.
-//
-// Another limitation of CrossCall is that the return value and output
-// parameters can only be uint32 integers. Returning complex structures or
-// strings is not supported.
-
-namespace sandbox {
-
-// max number of extended return parameters. See CrossCallReturn
-const size_t kExtendedReturnCount = 8;
-
-// Union of multiple types to be used as extended results
-// in the CrossCallReturn.
-union MultiType {
-  uint32 unsigned_int;
-  void* pointer;
-  HANDLE handle;
-  ULONG_PTR ulong_ptr;
-};
-
-// Maximum number of IPC parameters currently supported.
-// To increase this value, we have to:
-//  - Add another Callback typedef to Dispatcher.
-//  - Add another case to the switch on SharedMemIPCServer::InvokeCallback.
-//  - Add another case to the switch in GetActualAndMaxBufferSize
-const int kMaxIpcParams = 9;
-
-// Contains the information about a parameter in the ipc buffer.
-struct ParamInfo {
-  ArgType type_;
-  uint32 offset_;
-  uint32 size_;
-};
-
-// Models the return value and the return parameters of an IPC call
-// currently limited to one status code and eight generic return values
-// which cannot be pointers to other data. For x64 ports this structure
-// might have to use other integer types.
-struct CrossCallReturn {
-  // the IPC tag. It should match the original IPC tag.
-  uint32 tag;
-  // The result of the IPC operation itself.
-  ResultCode call_outcome;
-  // the result of the IPC call as executed in the server. The interpretation
-  // of this value depends on the specific service.
-  union {
-    NTSTATUS nt_status;
-    DWORD    win32_result;
-  };
-  // Number of extended return values.
-  uint32 extended_count;
-  // for calls that should return a windows handle. It is found here.
-  HANDLE handle;
-  // The array of extended values.
-  MultiType extended[kExtendedReturnCount];
-};
-
-// CrossCallParams base class that models the input params all packed in a
-// single compact memory blob. The representation can vary but in general a
-// given child of this class is meant to represent all input parameters
-// necessary to make a IPC call.
-//
-// This class cannot have virtual members because its assumed the IPC
-// parameters start from the 'this' pointer to the end, which is defined by
-// one of the subclasses
-//
-// Objects of this class cannot be constructed directly. Only derived
-// classes have the proper knowledge to construct it.
-class CrossCallParams {
- public:
-  // Returns the tag (ipc unique id) associated with this IPC.
-  uint32 GetTag() const {
-    return tag_;
-  }
-
-  // Returns the beggining of the buffer where the IPC params can be stored.
-  // prior to an IPC call
-  const void* GetBuffer() const {
-    return this;
-  }
-
-  // Returns how many parameter this IPC call should have.
-  const uint32 GetParamsCount() const {
-    return params_count_;
-  }
-
-  // Returns a pointer to the CrossCallReturn structure.
-  CrossCallReturn* GetCallReturn() {
-    return &call_return;
-  }
-
-  // Returns TRUE if this call contains InOut parameters.
-  const bool IsInOut() const {
-    return (1 == is_in_out_);
-  }
-
-  // Tells the CrossCall object if it contains InOut parameters.
-  void SetIsInOut(bool value) {
-    if (value)
-      is_in_out_ = 1;
-    else
-      is_in_out_ = 0;
-  }
-
- protected:
-  // constructs the IPC call params. Called only from the derived classes
-  CrossCallParams(uint32 tag, uint32 params_count)
-      : tag_(tag),
-        params_count_(params_count),
-        is_in_out_(0) {
-  }
-
- private:
-  uint32 tag_;
-  uint32 is_in_out_;
-  CrossCallReturn call_return;
-  const uint32 params_count_;
-  DISALLOW_COPY_AND_ASSIGN(CrossCallParams);
-};
-
-// ActualCallParams models an specific IPC call parameters with respect to the
-// storage allocation that the packed parameters should need.
-// NUMBER_PARAMS: the number of parameters, valid from 1 to N
-// BLOCK_SIZE: the total storage that the NUMBER_PARAMS parameters can take,
-// typically the block size is defined by the channel size of the underlying
-// ipc mechanism.
-// In practice this class is used to levergage C++ capacity to properly
-// calculate sizes and displacements given the possibility of the packed params
-// blob to be complex.
-//
-// As is, this class assumes that the layout of the blob is as follows. Assume
-// that NUMBER_PARAMS = 2 and a 32-bit build:
-//
-// [ tag                4 bytes]
-// [ IsOnOut            4 bytes]
-// [ call return       52 bytes]
-// [ params count       4 bytes]
-// [ parameter 0 type   4 bytes]
-// [ parameter 0 offset 4 bytes] ---delta to ---\
-// [ parameter 0 size   4 bytes]                |
-// [ parameter 1 type   4 bytes]                |
-// [ parameter 1 offset 4 bytes] ---------------|--\
-// [ parameter 1 size   4 bytes]                |  |
-// [ parameter 2 type   4 bytes]                |  |
-// [ parameter 2 offset 4 bytes] ----------------------\
-// [ parameter 2 size   4 bytes]                |  |   |
-// |---------------------------|                |  |   |
-// | value 0     (x bytes)     | <--------------/  |   |
-// | value 1     (y bytes)     | <-----------------/   |
-// |                           |                       |
-// | end of buffer             | <---------------------/
-// |---------------------------|
-//
-// Note that the actual number of params is NUMBER_PARAMS + 1
-// so that the size of each actual param can be computed from the difference
-// between one parameter and the next down. The offset of the last param
-// points to the end of the buffer and the type and size are undefined.
-//
-template <size_t NUMBER_PARAMS, size_t BLOCK_SIZE>
-class ActualCallParams : public CrossCallParams {
- public:
-  // constructor. Pass the ipc unique tag as input
-  explicit ActualCallParams(uint32 tag)
-      : CrossCallParams(tag, NUMBER_PARAMS) {
-    param_info_[0].offset_ = parameters_ - reinterpret_cast<char*>(this);
-  }
-
-  // Testing-only constructor. Allows setting the |number_params| to a
-  // wrong value.
-  ActualCallParams(uint32 tag, uint32 number_params)
-      : CrossCallParams(tag, number_params) {
-    param_info_[0].offset_ = parameters_ - reinterpret_cast<char*>(this);
-  }
-
-  // Testing-only method. Allows setting the apparent size to a wrong value.
-  // returns the previous size.
-  uint32 OverrideSize(uint32 new_size) {
-    uint32 previous_size = param_info_[NUMBER_PARAMS].offset_;
-    param_info_[NUMBER_PARAMS].offset_ = new_size;
-    return previous_size;
-  }
-
-  // Copies each paramter into the internal buffer. For each you must supply:
-  // index: 0 for the first param, 1 for the next an so on
-  bool CopyParamIn(uint32 index, const void* parameter_address, uint32 size,
-                   bool is_in_out, ArgType type) {
-    if (index >= NUMBER_PARAMS) {
-      return false;
-    }
-
-    if (kuint32max == size) {
-      // Memory error while getting the size.
-      return false;
-    }
-
-    if (size && !parameter_address) {
-      return false;
-    }
-
-    if (param_info_[index].offset_ > sizeof(*this)) {
-      // It does not fit, abort copy.
-      return false;
-    }
-
-    char* dest = reinterpret_cast<char*>(this) +  param_info_[index].offset_;
-
-    // We might be touching user memory, this has to be done from inside a try
-    // except.
-    __try {
-      memcpy(dest, parameter_address, size);
-    }
-    __except(EXCEPTION_EXECUTE_HANDLER) {
-      return false;
-    }
-
-    // Set the flag to tell the broker to update the buffer once the call is
-    // made.
-    if (is_in_out)
-      SetIsInOut(true);
-
-    param_info_[index + 1].offset_ = Align(param_info_[index].offset_ +
-                                                size);
-    param_info_[index].size_ = size;
-    param_info_[index].type_ = type;
-    return true;
-  }
-
-  // Returns a pointer to a parameter in the memory section.
-  void* GetParamPtr(size_t index) {
-    return reinterpret_cast<char*>(this) + param_info_[index].offset_;
-  }
-
-  // Returns the total size of the buffer. Only valid once all the paramters
-  // have been copied in with CopyParamIn.
-  uint32 GetSize() const {
-    return param_info_[NUMBER_PARAMS].offset_;
-  }
-
- protected:
-  ActualCallParams() : CrossCallParams(0, NUMBER_PARAMS) { }
-
- private:
-  ParamInfo param_info_[NUMBER_PARAMS + 1];
-  char parameters_[BLOCK_SIZE - sizeof(CrossCallParams)
-                   - sizeof(ParamInfo) * (NUMBER_PARAMS + 1)];
-  DISALLOW_COPY_AND_ASSIGN(ActualCallParams);
-};
-
-COMPILE_ASSERT(sizeof(ActualCallParams<1, 1024>) == 1024, bad_size_buffer);
-COMPILE_ASSERT(sizeof(ActualCallParams<2, 1024>) == 1024, bad_size_buffer);
-COMPILE_ASSERT(sizeof(ActualCallParams<3, 1024>) == 1024, bad_size_buffer);
-
-}  // namespace sandbox
-
-#endif  // SANDBOX_SRC_CROSSCALL_PARAMS_H__