// Copyright (c) 2011 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 InterceptionManager, the class in charge of setting up interceptions
// for the sandboxed process. For more details see
// http://dev.chromium.org/developers/design-documents/sandbox .
#ifndef SANDBOX_SRC_INTERCEPTION_H_
#define SANDBOX_SRC_INTERCEPTION_H_
#include <list>
#include <string>
#include "base/basictypes.h"
#include "base/gtest_prod_util.h"
#include "base/strings/string16.h"
#include "sandbox/win/src/sandbox_types.h"
namespace sandbox {
class TargetProcess;
enum InterceptorId;
// Internal structures used for communication between the broker and the target.
struct DllPatchInfo;
struct DllInterceptionData;
// The InterceptionManager executes on the parent application, and it is in
// charge of setting up the desired interceptions, and placing the Interception
// Agent into the child application.
//
// The exposed API consists of two methods: AddToPatchedFunctions to set up a
// particular interception, and InitializeInterceptions to actually go ahead and
// perform all interceptions and transfer data to the child application.
//
// The typical usage is something like this:
//
// InterceptionManager interception_manager(child);
// if (!interception_manager.AddToPatchedFunctions(
// L"ntdll.dll", "NtCreateFile",
// sandbox::INTERCEPTION_SERVICE_CALL, &MyNtCreateFile, MY_ID_1))
// return false;
//
// if (!interception_manager.AddToPatchedFunctions(
// L"kernel32.dll", "CreateDirectoryW",
// sandbox::INTERCEPTION_EAT, L"MyCreateDirectoryW@12", MY_ID_2))
// return false;
//
// if (!interception_manager.InitializeInterceptions()) {
// DWORD error = ::GetLastError();
// return false;
// }
//
// Any required syncronization must be performed outside this class. Also, it is
// not possible to perform further interceptions after InitializeInterceptions
// is called.
//
class InterceptionManager {
// The unit test will access private members.
// Allow tests to be marked DISABLED_. Note that FLAKY_ and FAILS_ prefixes
// do not work with sandbox tests.
FRIEND_TEST_ALL_PREFIXES(InterceptionManagerTest, BufferLayout1);
FRIEND_TEST_ALL_PREFIXES(InterceptionManagerTest, BufferLayout2);
public:
// An interception manager performs interceptions on a given child process.
// If we are allowed to intercept functions that have been patched by somebody
// else, relaxed should be set to true.
// Note: We increase the child's reference count internally.
InterceptionManager(TargetProcess* child_process, bool relaxed);
~InterceptionManager();
// Patches function_name inside dll_name to point to replacement_code_address.
// function_name has to be an exported symbol of dll_name.
// Returns true on success.
//
// The new function should match the prototype and calling convention of the
// function to intercept except for one extra argument (the first one) that
// contains a pointer to the original function, to simplify the development
// of interceptors (for IA32). In x64, there is no extra argument to the
// interceptor, so the provided InterceptorId is used to keep a table of
// intercepted functions so that the interceptor can index that table to get
// the pointer that would have been the first argument (g_originals[id]).
//
// For example, to intercept NtClose, the following code could be used:
//
// typedef NTSTATUS (WINAPI *NtCloseFunction) (IN HANDLE Handle);
// NTSTATUS WINAPI MyNtCose(IN NtCloseFunction OriginalClose,
// IN HANDLE Handle) {
// // do something
// // call the original function
// return OriginalClose(Handle);
// }
//
// And in x64:
//
// typedef NTSTATUS (WINAPI *NtCloseFunction) (IN HANDLE Handle);
// NTSTATUS WINAPI MyNtCose64(IN HANDLE Handle) {
// // do something
// // call the original function
// NtCloseFunction OriginalClose = g_originals[NT_CLOSE_ID];
// return OriginalClose(Handle);
// }
bool AddToPatchedFunctions(const wchar_t* dll_name,
const char* function_name,
InterceptionType interception_type,
const void* replacement_code_address,
InterceptorId id);
// Patches function_name inside dll_name to point to
// replacement_function_name.
bool AddToPatchedFunctions(const wchar_t* dll_name,
const char* function_name,
InterceptionType interception_type,
const char* replacement_function_name,
InterceptorId id);
// The interception agent will unload the dll with dll_name.
bool AddToUnloadModules(const wchar_t* dll_name);
// Initializes all interceptions on the client.
// Returns true on success.
//
// The child process must be created suspended, and cannot be resumed until
// after this method returns. In addition, no action should be performed on
// the child that may cause it to resume momentarily, such as injecting
// threads or APCs.
//
// This function must be called only once, after all interceptions have been
// set up using AddToPatchedFunctions.
bool InitializeInterceptions();
private:
// Used to store the interception information until the actual set-up.
struct InterceptionData {
InterceptionType type; // Interception type.
InterceptorId id; // Interceptor id.
base::string16 dll; // Name of dll to intercept.
std::string function; // Name of function to intercept.
std::string interceptor; // Name of interceptor function.
const void* interceptor_address; // Interceptor's entry point.
};
// Calculates the size of the required configuration buffer.
size_t GetBufferSize() const;
// Rounds up the size of a given buffer, considering alignment (padding).
// value is the current size of the buffer, and alignment is specified in
// bytes.
static inline size_t RoundUpToMultiple(size_t value, size_t alignment) {
return ((value + alignment -1) / alignment) * alignment;
}
// Sets up a given buffer with all the information that has to be transfered
// to the child.
// Returns true on success.
//
// The buffer size should be at least the value returned by GetBufferSize
bool SetupConfigBuffer(void* buffer, size_t buffer_bytes);
// Fills up the part of the transfer buffer that corresponds to information
// about one dll to patch.
// data is the first recorded interception for this dll.
// Returns true on success.
//
// On successful return, buffer will be advanced from it's current position
// to the point where the next block of configuration data should be written
// (the actual interception info), and the current size of the buffer will
// decrease to account the space used by this method.
bool SetupDllInfo(const InterceptionData& data,
void** buffer, size_t* buffer_bytes) const;
// Fills up the part of the transfer buffer that corresponds to a single
// function to patch.
// dll_info points to the dll being updated with the interception stored on
// data. The buffer pointer and remaining size are updated by this call.
// Returns true on success.
bool SetupInterceptionInfo(const InterceptionData& data, void** buffer,
size_t* buffer_bytes,
DllPatchInfo* dll_info) const;
// Returns true if this interception is to be performed by the child
// as opposed to from the parent.
bool IsInterceptionPerformedByChild(const InterceptionData& data) const;
// Allocates a buffer on the child's address space (returned on
// remote_buffer), and fills it with the contents of a local buffer.
// Returns true on success.
bool CopyDataToChild(const void* local_buffer, size_t buffer_bytes,
void** remote_buffer) const;
// Performs the cold patch (from the parent) of ntdll.
// Returns true on success.
//
// This method will insert additional interceptions to launch the interceptor
// agent on the child process, if there are additional interceptions to do.
bool PatchNtdll(bool hot_patch_needed);
// Peforms the actual interceptions on ntdll.
// thunks is the memory to store all the thunks for this dll (on the child),
// and dll_data is a local buffer to hold global dll interception info.
// Returns true on success.
bool PatchClientFunctions(DllInterceptionData* thunks,
size_t thunk_bytes,
DllInterceptionData* dll_data);
// The process to intercept.
TargetProcess* child_;
// Holds all interception info until the call to initialize (perform the
// actual patch).
std::list<InterceptionData> interceptions_;
// Keep track of patches added by name.
bool names_used_;
// true if we are allowed to patch already-patched functions.
bool relaxed_;
DISALLOW_COPY_AND_ASSIGN(InterceptionManager);
};
// This macro simply calls interception_manager.AddToPatchedFunctions with
// the given service to intercept (INTERCEPTION_SERVICE_CALL), and assumes that
// the interceptor is called "TargetXXX", where XXX is the name of the service.
// Note that num_params is the number of bytes to pop out of the stack for
// the exported interceptor, following the calling convention of a service call
// (WINAPI = with the "C" underscore).
#if SANDBOX_EXPORTS
#if defined(_WIN64)
#define MAKE_SERVICE_NAME(service, params) "Target" # service "64"
#else
#define MAKE_SERVICE_NAME(service, params) "_Target" # service "@" # params
#endif
#define ADD_NT_INTERCEPTION(service, id, num_params) \
AddToPatchedFunctions(kNtdllName, #service, \
sandbox::INTERCEPTION_SERVICE_CALL, \
MAKE_SERVICE_NAME(service, num_params), id)
#define INTERCEPT_NT(manager, service, id, num_params) \
((&Target##service) ? \
manager->ADD_NT_INTERCEPTION(service, id, num_params) : false)
// When intercepting the EAT it is important that the patched version of the
// function not call any functions imported from system libraries unless
// |TargetServices::InitCalled()| returns true, because it is only then that
// we are guaranteed that our IAT has been initialized.
#define INTERCEPT_EAT(manager, dll, function, id, num_params) \
((&Target##function) ? \
manager->AddToPatchedFunctions(dll, #function, sandbox::INTERCEPTION_EAT, \
MAKE_SERVICE_NAME(function, num_params), \
id) : \
false)
#else // SANDBOX_EXPORTS
#if defined(_WIN64)
#define MAKE_SERVICE_NAME(service) &Target##service##64
#else
#define MAKE_SERVICE_NAME(service) &Target##service
#endif
#define ADD_NT_INTERCEPTION(service, id, num_params) \
AddToPatchedFunctions(kNtdllName, #service, \
sandbox::INTERCEPTION_SERVICE_CALL, \
MAKE_SERVICE_NAME(service), id)
#define INTERCEPT_NT(manager, service, id, num_params) \
manager->ADD_NT_INTERCEPTION(service, id, num_params)
// When intercepting the EAT it is important that the patched version of the
// function not call any functions imported from system libraries unless
// |TargetServices::InitCalled()| returns true, because it is only then that
// we are guaranteed that our IAT has been initialized.
#define INTERCEPT_EAT(manager, dll, function, id, num_params) \
manager->AddToPatchedFunctions(dll, #function, sandbox::INTERCEPTION_EAT, \
MAKE_SERVICE_NAME(function), id)
#endif // SANDBOX_EXPORTS
} // namespace sandbox
#endif // SANDBOX_SRC_INTERCEPTION_H_