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 // Copyright (c) 2010 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.

 // Defines ResolverThunk, the interface for classes that perform interceptions.

 // For more details see

 // http://dev.chromium.org/developers/design-documents/sandbox .

 #include "base/basictypes.h"

 #include "sandbox/win/src/nt_internals.h"

 #ifndef SANDBOX_SRC_RESOLVER_H__

 #define SANDBOX_SRC_RESOLVER_H__

 namespace sandbox {

 // A resolver is the object in charge of performing the actual interception of

 // a function. There should be a concrete implementation of a resolver roughly

 // per type of interception.

 class ResolverThunk {

  public:

   ResolverThunk() {}

   virtual ~ResolverThunk() {}

   // Performs the actual interception of a function.

   // target_name is an exported function from the module loaded at

   // target_module, and must be replaced by interceptor_name, exported from

   // interceptor_module. interceptor_entry_point can be provided instead of

   // interceptor_name / interceptor_module.

   // thunk_storage must point to a buffer on the child's address space, to hold

   // the patch thunk, and related data. If provided, storage_used will receive

   // the number of bytes used from thunk_storage.

   //

   // Example: (without error checking)

   //

   // size_t size = resolver.GetThunkSize();

   // char* buffer = ::VirtualAllocEx(child_process, NULL, size,

   //                                 MEM_COMMIT, PAGE_READWRITE);

   // resolver.Setup(ntdll_module, NULL, L"NtCreateFile", NULL,

   //                &MyReplacementFunction, buffer, size, NULL);

   //

   // In general, the idea is to allocate a single big buffer for all

   // interceptions on the same dll, and call Setup n times.

   // WARNING: This means that any data member that is specific to a single

   // interception must be reset within this method.

   virtual NTSTATUS Setup(const void* target_module,

                          const void* interceptor_module,

                          const char* target_name,

                          const char* interceptor_name,

                          const void* interceptor_entry_point,

                          void* thunk_storage,

                          size_t storage_bytes,

                          size_t* storage_used) = 0;

   // Gets the address of function_name inside module (main exe).

   virtual NTSTATUS ResolveInterceptor(const void* module,

                                       const char* function_name,

                                       const void** address);

   // Gets the address of an exported function_name inside module.

   virtual NTSTATUS ResolveTarget(const void* module,

                                  const char* function_name,

                                  void** address);

   // Gets the required buffer size for this type of thunk.

   virtual size_t GetThunkSize() const = 0;

  protected:

   // Performs basic initialization on behalf of a concrete instance of a

   // resolver. That is, parameter validation and resolution of the target

   // and the interceptor into the member variables.

   //

   // target_name is an exported function from the module loaded at

   // target_module, and must be replaced by interceptor_name, exported from

   // interceptor_module. interceptor_entry_point can be provided instead of

   // interceptor_name / interceptor_module.

   // thunk_storage must point to a buffer on the child's address space, to hold

   // the patch thunk, and related data.

   virtual NTSTATUS Init(const void* target_module,

                         const void* interceptor_module,

                         const char* target_name,

                         const char* interceptor_name,

                         const void* interceptor_entry_point,

                         void* thunk_storage,

                         size_t storage_bytes);

   // Gets the required buffer size for the internal part of the thunk.

   size_t GetInternalThunkSize() const;

   // Initializes the internal part of the thunk.

   // interceptor is the function to be called instead of original_function.

   bool SetInternalThunk(void* storage, size_t storage_bytes,

                         const void* original_function, const void* interceptor);

   // Holds the resolved interception target.

   void* target_;

   // Holds the resolved interception interceptor.

   const void* interceptor_;

   DISALLOW_COPY_AND_ASSIGN(ResolverThunk);

 };

 }  // namespace sandbox

 #endif  // SANDBOX_SRC_RESOLVER_H__