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mirror of https://github.com/valinet/ExplorerPatcher.git synced 2024-11-12 02:00:46 +01:00

ep_extra: Implemented an ep_extra-based loader

ExplorerPatcher includes a mechanism which allows the user to load
a single DLL, named `ep_extra.dll` and placed in `C:\Windows` when
`explorer.exe` loads. This was long requested by some users who wanted
to perform their own code/initializations/hooks when `explorer` started.

In the mean time, I thought `ep_extra.dll` would work nicely as a
loader for any number of modules. I could've included this functionality
in the main ExplorerPatcher code, but I decided to take it up as a
challenge instead and offer a robust implementation without changing
ExplorerPatcher's main code.

Thus, when using this as `ep_extra.dll`, it will also load DLLs that
match the `ep_extra_*.dll` pattern. These DLLs must export a function
called `setup` which the loader will execute on the thread that is
loading the DLLs. Although not currently checked, return 0 from this
function if your initialization succeeded, or some error code when it
fails.

What's up with the assembly and shell codes and weird threads that I
create? Well, I realized I kind of did a mistake when coding
ExplorerPatcher, in that I should have loaded and executed `ep_extra`
on a seprate thread, not in `explorer`'s main thread. But since I said
I'd do this challenge without changing EP, this was my solution
towards having this `ep_extra` loader do its work, load the other DLLs,
if any, and then unload itself from memory safely and (almost) cleanly
without disturbing the main application right after it does its job.
This way, you can update it seamlessly when `explorer` is running,
which is much more convenient than having to kill `explorer`, replace
the DLL, and then manually reload `explorer`. I don't know if this is
the best way, but it is the way I thought about when realizing that I
cannot call `FreeLibrary` simply, since the "next line" (which would
have been a "return") is well outside of valid memory at that point.
`FreeLibraryAndExitThread` also can't be used since I do not want to
exit `explorer`'s main thread which the loader's function is called on.
This commit is contained in:
Valentin Radu 2023-03-01 20:27:44 +02:00
parent 7c4567ac79
commit 1f4b586f03
7 changed files with 435 additions and 0 deletions

5
ep_extra/README.md Normal file
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# ExplorerPatcher Custom Libraries Chainloader
ExplorerPatcher has a simple, built-in mechanism that allows users to load their own DLL into `explorer.exe` right after ExplorerPatcher finishes initializing its hooks. Interested users hould place a DLL called `ep_extra.dll` in `C:\Windows`. When ExplorerPatcher finishes its setup, it loads the `ep_extra.dll` library and calls the `ep_extra_EntryPoint` function. Although this is very useful so that users can load their custom code, it is quite limited at the moment, as it loads just one DLL.
This project is a solution to this issue. A chainloader is implemented here, that looks for other modules matching the `ep_extra_*.dll` pattern in `C:\Windows` as well, and loads them one after the other.

100
ep_extra/ep_extra.rc Normal file
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// Microsoft Visual C++ generated resource script.
//
#include "resource.h"
#define APSTUDIO_READONLY_SYMBOLS
/////////////////////////////////////////////////////////////////////////////
//
// Generated from the TEXTINCLUDE 2 resource.
//
#include "winres.h"
/////////////////////////////////////////////////////////////////////////////
#undef APSTUDIO_READONLY_SYMBOLS
/////////////////////////////////////////////////////////////////////////////
// English (United States) resources
#if !defined(AFX_RESOURCE_DLL) || defined(AFX_TARG_ENU)
LANGUAGE LANG_ENGLISH, SUBLANG_ENGLISH_US
#pragma code_page(1252)
#ifdef APSTUDIO_INVOKED
/////////////////////////////////////////////////////////////////////////////
//
// TEXTINCLUDE
//
1 TEXTINCLUDE
BEGIN
"resource.h\0"
END
2 TEXTINCLUDE
BEGIN
"#include ""winres.h""\r\n"
"\0"
END
3 TEXTINCLUDE
BEGIN
"\r\n"
"\0"
END
#endif // APSTUDIO_INVOKED
/////////////////////////////////////////////////////////////////////////////
//
// Version
//
VS_VERSION_INFO VERSIONINFO
FILEVERSION 1,0,0,1
PRODUCTVERSION 1,0,0,1
FILEFLAGSMASK 0x3fL
#ifdef _DEBUG
FILEFLAGS 0x1L
#else
FILEFLAGS 0x0L
#endif
FILEOS 0x40004L
FILETYPE 0x2L
FILESUBTYPE 0x0L
BEGIN
BLOCK "StringFileInfo"
BEGIN
BLOCK "040904b0"
BEGIN
VALUE "CompanyName", "VALINET Solutions SRL"
VALUE "FileDescription", "ExplorerPatcher Custom Libraries Chainloader"
VALUE "FileVersion", "1.0.0.0"
VALUE "InternalName", "ep_extra.dll"
VALUE "LegalCopyright", "Copyright (C) 2006-2022 VALINET Solutions SRL. All rights reserved."
VALUE "OriginalFilename", "ep_extra.dll"
VALUE "ProductName", "ExplorerPatcher"
VALUE "ProductVersion", "1.0.0.0"
END
END
BLOCK "VarFileInfo"
BEGIN
VALUE "Translation", 0x409, 1200
END
END
#endif // English (United States) resources
/////////////////////////////////////////////////////////////////////////////
#ifndef APSTUDIO_INVOKED
/////////////////////////////////////////////////////////////////////////////
//
// Generated from the TEXTINCLUDE 3 resource.
//
/////////////////////////////////////////////////////////////////////////////
#endif // not APSTUDIO_INVOKED

179
ep_extra/ep_extra.vcxproj Normal file
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<?xml version="1.0" encoding="utf-8"?>
<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<ItemGroup Label="ProjectConfigurations">
<ProjectConfiguration Include="Debug|Win32">
<Configuration>Debug</Configuration>
<Platform>Win32</Platform>
</ProjectConfiguration>
<ProjectConfiguration Include="Release|Win32">
<Configuration>Release</Configuration>
<Platform>Win32</Platform>
</ProjectConfiguration>
<ProjectConfiguration Include="Debug|x64">
<Configuration>Debug</Configuration>
<Platform>x64</Platform>
</ProjectConfiguration>
<ProjectConfiguration Include="Release|x64">
<Configuration>Release</Configuration>
<Platform>x64</Platform>
</ProjectConfiguration>
</ItemGroup>
<PropertyGroup Label="Globals">
<VCProjectVersion>16.0</VCProjectVersion>
<Keyword>Win32Proj</Keyword>
<ProjectGuid>{93fa47cc-7753-4f86-b583-69048f51c5ab}</ProjectGuid>
<RootNamespace>epextra</RootNamespace>
<WindowsTargetPlatformVersion>10.0</WindowsTargetPlatformVersion>
</PropertyGroup>
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<CharacterSet>Unicode</CharacterSet>
</PropertyGroup>
<Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />
<ImportGroup Label="ExtensionSettings">
<Import Project="$(VCTargetsPath)\BuildCustomizations\masm.props" />
</ImportGroup>
<ImportGroup Label="Shared">
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<PropertyGroup Label="UserMacros" />
<PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
<LinkIncremental>true</LinkIncremental>
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<PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
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<OutDir>$(SolutionDir)\build\$(Configuration)</OutDir>
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<PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
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<OutDir>$(SolutionDir)\build\$(Configuration)</OutDir>
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<PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'">
<LinkIncremental>false</LinkIncremental>
<OutDir>$(SolutionDir)\build\$(Configuration)</OutDir>
</PropertyGroup>
<ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
<ClCompile>
<WarningLevel>Level3</WarningLevel>
<SDLCheck>true</SDLCheck>
<PreprocessorDefinitions>WIN32;_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
<ConformanceMode>true</ConformanceMode>
<RuntimeLibrary>MultiThreadedDebug</RuntimeLibrary>
</ClCompile>
<Link>
<SubSystem>Console</SubSystem>
<GenerateDebugInformation>true</GenerateDebugInformation>
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<AdditionalOptions>%(AdditionalOptions)</AdditionalOptions>
</Link>
<MASM />
</ItemDefinitionGroup>
<ItemGroup>
<ClCompile Include="worker.c" />
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<ItemGroup>
<MASM Include="main.asm" />
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<ItemGroup>
<ClInclude Include="resource.h" />
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<ResourceCompile Include="ep_extra.rc" />
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<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<ItemGroup>
<Filter Include="Source Files">
<UniqueIdentifier>{4FC737F1-C7A5-4376-A066-2A32D752A2FF}</UniqueIdentifier>
<Extensions>cpp;c;cc;cxx;c++;cppm;ixx;def;odl;idl;hpj;bat;asm;asmx</Extensions>
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<UniqueIdentifier>{93995380-89BD-4b04-88EB-625FBE52EBFB}</UniqueIdentifier>
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<UniqueIdentifier>{67DA6AB6-F800-4c08-8B7A-83BB121AAD01}</UniqueIdentifier>
<Extensions>rc;ico;cur;bmp;dlg;rc2;rct;bin;rgs;gif;jpg;jpeg;jpe;resx;tiff;tif;png;wav;mfcribbon-ms</Extensions>
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<ClCompile Include="worker.c">
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<ItemGroup>
<MASM Include="main.asm">
<Filter>Source Files</Filter>
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<ItemGroup>
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18
ep_extra/main.asm Normal file
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EXTERN worker : PROC
.CODE
ep_extra_EntryPoint PROC EXPORT
PUSH RBP
MOV RBP, RSP
SUB RSP, 30H
CALL worker
CMP RAX, 0
JE finish
JMP RAX
finish:
LEAVE
RET
ep_extra_EntryPoint ENDP
END

14
ep_extra/resource.h Normal file
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//{{NO_DEPENDENCIES}}
// Microsoft Visual C++ generated include file.
// Used by ep_extra.rc
// Next default values for new objects
//
#ifdef APSTUDIO_INVOKED
#ifndef APSTUDIO_READONLY_SYMBOLS
#define _APS_NEXT_RESOURCE_VALUE 101
#define _APS_NEXT_COMMAND_VALUE 40001
#define _APS_NEXT_CONTROL_VALUE 1001
#define _APS_NEXT_SYMED_VALUE 101
#endif
#endif

82
ep_extra/worker.c Normal file
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#include <Windows.h>
#include <Shlwapi.h>
#pragma comment(lib, "Shlwapi.lib")
#include <stdio.h>
HMODULE hModule = NULL;
HANDLE sigFinish = NULL;
void* pFinishProc = NULL;
void done() {
WaitForSingleObject(sigFinish, INFINITE);
FreeLibraryAndExitThread(hModule, 0);
}
void* worker() {
wchar_t pattern[MAX_PATH];
GetWindowsDirectoryW(pattern, MAX_PATH);
wcscat_s(pattern, MAX_PATH, L"\\ep_extra_*.dll");
WIN32_FIND_DATA data;
HANDLE hFind = FindFirstFileW(pattern, &data);
if (hFind != INVALID_HANDLE_VALUE) {
do {
wprintf(L">> Found ep_extra library: \"%s\"\n", data.cFileName);
GetWindowsDirectoryW(pattern, MAX_PATH);
wcscat_s(pattern, MAX_PATH, L"\\");
wcscat_s(pattern, MAX_PATH, data.cFileName);
HMODULE hLib = LoadLibraryW(pattern);
if (hLib) {
FARPROC proc = (FARPROC)(GetProcAddress(hLib, "setup"));
if (proc) {
if (!proc()) FreeLibrary(hLib);
}
else FreeLibrary(hLib);
}
} while (FindNextFileW(hFind, &data));
FindClose(hFind);
}
sigFinish = CreateEventW(NULL, FALSE, FALSE, NULL);
if (sigFinish) {
BYTE payload[] = {
0x48, 0xB9, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // mov rcx, sigFinish
0x48, 0xB8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // mov rax, SetEvent
0xFF, 0xD0, // call SetEvent
0xC9, // leave
0xC3 // ret
};
*(INT64*)(payload + 2) = sigFinish;
*(INT64*)(payload + 12) = SetEvent;
pFinishProc = VirtualAlloc(NULL, sizeof(payload), MEM_COMMIT, PAGE_EXECUTE_READWRITE);
if (pFinishProc) {
memcpy(pFinishProc, payload, sizeof(payload));
SHCreateThread(done, 0, CTF_NOADDREFLIB, NULL);
return pFinishProc;
}
}
return NULL;
}
BOOL WINAPI DllMain(
_In_ HINSTANCE hinstDLL,
_In_ DWORD fdwReason,
_In_ LPVOID lpvReserved
)
{
switch (fdwReason)
{
case DLL_PROCESS_ATTACH:
DisableThreadLibraryCalls(hinstDLL);
hModule = hinstDLL;
break;
case DLL_THREAD_ATTACH:
break;
case DLL_THREAD_DETACH:
break;
case DLL_PROCESS_DETACH:
break;
}
return TRUE;
}