shimlib.c File Reference

#include <windef.h>
#include <winbase.h>
#include <shimlib.h>
#include <strsafe.h>
#include <ndk/rtlfuncs.h>

Include dependency graph for shimlib.c:

Go to the source code of this file.

Classes
struct	UsedShim

Macros
#define	WIN32_NO_STATUS

Typedefs
typedef struct UsedShim	UsedShim
typedef struct UsedShim *	pUsedShim

Functions
void	ShimLib_Init (HINSTANCE hInstance)
void	ShimLib_Deinit (VOID)
PVOID	ShimLib_ShimMalloc (SIZE_T dwSize)
void	ShimLib_ShimFree (PVOID pData)
HINSTANCE	ShimLib_Instance (VOID)
PCSTR	ShimLib_StringNDuplicateA (PCSTR szString, SIZE_T stringLengthIncludingNullTerm)
PCSTR	ShimLib_StringDuplicateA (PCSTR szString)
BOOL	ShimLib_StrAEqualsWNC (PCSTR szString, PCWSTR wszString)
	_SHMALLOC (".shm$AAA")
	_SHMALLOC (".shm$ZZZ")
PHOOKAPI WINAPI	ShimLib_GetHookAPIs (IN LPCSTR szCommandLine, IN LPCWSTR wszShimName, OUT PDWORD pdwHookCount)
BOOL WINAPI	ShimLib_NotifyShims (DWORD fdwReason, PVOID ptr)
VOID	SeiInitDebugSupport (VOID)
BOOL WINAPIV	SeiDbgPrint (SEI_LOG_LEVEL Level, PCSTR Function, PCSTR Format,...)

Variables
ULONG	g_ShimEngDebugLevel = 0xffffffff
static HINSTANCE	g_ShimLib_hInstance
static HANDLE	g_ShimLib_Heap
static PSLIST_HEADER	g_UsedShims

Macro Definition Documentation

WIN32_NO_STATUS

#define WIN32_NO_STATUS

Definition at line 8 of file shimlib.c.

Typedef Documentation

pUsedShim

typedef struct UsedShim * pUsedShim

UsedShim

typedef struct UsedShim UsedShim

Function Documentation

_SHMALLOC() [1/2]

_SHMALLOC

(

".shm$AAA"

)

Definition at line 103 of file shimlib.c.

{ 0 };

_SHMALLOC() [2/2]

_SHMALLOC

(

".shm$ZZZ"

)

Definition at line 104 of file shimlib.c.

{ 0 };

SeiDbgPrint()

BOOL WINAPIV SeiDbgPrint	(	SEI_LOG_LEVEL	Level,
		PCSTR	Function,
		PCSTR	Format,
			...
	)

Outputs diagnostic info.

Parameters

[in]	Level	The level to log this message with, choose any of [SHIM_ERR, SHIM_WARN, SHIM_INFO].
[in]	FunctionName	The function this log should be attributed to.
[in]	Format	The format string.
	...	Variable arguments providing additional information.

Returns

Success: TRUE Failure: FALSE.

Definition at line 197 of file shimlib.c.

{
    char Buffer[512];
    char* Current = Buffer;
    const char* LevelStr;
    size_t Length = sizeof(Buffer);
    va_list ArgList;
    HRESULT hr;

    if (g_ShimEngDebugLevel == 0xffffffff)
        SeiInitDebugSupport();

    if (Level > g_ShimEngDebugLevel)
        return FALSE;

    switch (Level)
    {
    case SEI_MSG:
        LevelStr = "MSG ";
        break;
    case SEI_FAIL:
        LevelStr = "FAIL";
        break;
    case SEI_WARN:
        LevelStr = "WARN";
        break;
    case SEI_INFO:
        LevelStr = "INFO";
        break;
    default:
        LevelStr = "USER";
        break;
    }

    if (Function)
        hr = StringCchPrintfExA(Current, Length, &Current, &Length, STRSAFE_NULL_ON_FAILURE, "[%s] [%s] ", LevelStr, Function);
    else
        hr = StringCchPrintfExA(Current, Length, &Current, &Length, STRSAFE_NULL_ON_FAILURE, "[%s] ", LevelStr);

    if (!SUCCEEDED(hr))
        return FALSE;

    va_start(ArgList, Format);
    hr = StringCchVPrintfExA(Current, Length, &Current, &Length, STRSAFE_NULL_ON_FAILURE, Format, ArgList);
    va_end(ArgList);
    if (!SUCCEEDED(hr))
        return FALSE;

    DbgPrint("%s", Buffer);
    return TRUE;
}

SeiInitDebugSupport()

VOID SeiInitDebugSupport

(

VOID

)

Definition at line 165 of file shimlib.c.

{
    static const UNICODE_STRING DebugKey = RTL_CONSTANT_STRING(L"SHIM_DEBUG_LEVEL");
    UNICODE_STRING DebugValue;
    NTSTATUS Status;
    ULONG NewLevel = SEI_MSG;
    WCHAR Buffer[40];

    RtlInitEmptyUnicodeString(&DebugValue, Buffer, sizeof(Buffer));

    Status = RtlQueryEnvironmentVariable_U(NULL, &DebugKey, &DebugValue);

    if (NT_SUCCESS(Status))
    {
        if (!NT_SUCCESS(RtlUnicodeStringToInteger(&DebugValue, 10, &NewLevel)))
            NewLevel = 0;
    }
    g_ShimEngDebugLevel = NewLevel;
}

Referenced by SeiDbgPrint().

ShimLib_Deinit()

void ShimLib_Deinit

(

VOID

)

Definition at line 39 of file shimlib.c.

{
    // Is this a good idea?
    HeapDestroy(g_ShimLib_Heap);
}

Referenced by DllMain().

ShimLib_GetHookAPIs()

PHOOKAPI WINAPI ShimLib_GetHookAPIs	(	IN LPCSTR	szCommandLine,
		IN LPCWSTR	wszShimName,
		OUT PDWORD	pdwHookCount
	)

Definition at line 111 of file shimlib.c.

{
    PSHIMREG ps = &_shim_start;
    ps++;
    for (; ps < &_shim_end; ps++)
    {
        if (ps->GetHookAPIs != NULL && ps->ShimName != NULL)
        {
            if (ShimLib_StrAEqualsWNC(ps->ShimName, wszShimName))
            {
                pUsedShim shim = (pUsedShim)ShimLib_ShimMalloc(sizeof(UsedShim));
                shim->pShim = ps;
#if (WINVER > _WIN32_WINNT_WS03)
                shim->bInitCalled = FALSE;
#endif
                RtlInterlockedPushEntrySList(g_UsedShims, &(shim->Entry));

                return ps->GetHookAPIs(SHIM_NOTIFY_ATTACH, szCommandLine, pdwHookCount);
            }
        }
    }
    return NULL;
}

Referenced by GetHookAPIs().

ShimLib_Init()

void ShimLib_Init

(

HINSTANCE

hInstance

)

Definition at line 30 of file shimlib.c.

{
    g_ShimLib_hInstance = hInstance;
    g_ShimLib_Heap = HeapCreate(0, 0x10000, 0);

    g_UsedShims = (PSLIST_HEADER)ShimLib_ShimMalloc(sizeof(SLIST_HEADER));
    RtlInitializeSListHead(g_UsedShims);
}

Referenced by DllMain().

ShimLib_Instance()

HINSTANCE ShimLib_Instance

(

VOID

)

Definition at line 55 of file shimlib.c.

{
    return g_ShimLib_hInstance;
}

Referenced by APIHook_FreeLibrary(), APIHook_GetProcAddress(), APIHook_LoadLibraryA(), APIHook_LoadLibraryExA(), APIHook_LoadLibraryExW(), and APIHook_LoadLibraryW().

ShimLib_NotifyShims()

BOOL WINAPI ShimLib_NotifyShims	(	DWORD	fdwReason,
		PVOID	ptr
	)

Definition at line 136 of file shimlib.c.

{
    PSLIST_ENTRY pEntry = RtlFirstEntrySList(g_UsedShims);

    if (fdwReason < SHIM_REASON_INIT)
        fdwReason += (SHIM_REASON_INIT - SHIM_NOTIFY_ATTACH);

    while (pEntry)
    {
        pUsedShim pUsed = CONTAINING_RECORD(pEntry, UsedShim, Entry);
        _PVNotify Notify = pUsed->pShim->Notify;
#if (WINVER > _WIN32_WINNT_WS03)
        if (pUsed->bInitCalled && fdwReason == SHIM_REASON_INIT)
            Notify = NULL;
#endif
        if (Notify)
            Notify(fdwReason, ptr);
#if (WINVER > _WIN32_WINNT_WS03)
        if (fdwReason == SHIM_REASON_INIT)
            pUsed->bInitCalled = TRUE;
#endif

        pEntry = pEntry->Next;
    }

    return TRUE;
}

Referenced by NotifyShims().

ShimLib_ShimFree()

void ShimLib_ShimFree

(

PVOID

pData

)

Definition at line 50 of file shimlib.c.

{
    HeapFree(g_ShimLib_Heap, 0, pData);
}

Referenced by FreeLibrary(), and InitIgnoreFreeLibrary().

ShimLib_ShimMalloc()

PVOID ShimLib_ShimMalloc

(

SIZE_T

dwSize

)

Definition at line 45 of file shimlib.c.

{
    return HeapAlloc(g_ShimLib_Heap, 0, dwSize);
}

Referenced by FreeLibrary(), InitIgnoreFreeLibrary(), ShimLib_GetHookAPIs(), ShimLib_Init(), and ShimLib_StringNDuplicateA().

ShimLib_StrAEqualsWNC()

BOOL ShimLib_StrAEqualsWNC	(	PCSTR	szString,
		PCWSTR	wszString
	)

Definition at line 72 of file shimlib.c.

{
    while (toupper(*szString) == towupper(*wszString))
    {
        if (!*szString)
            return TRUE;

        szString++; wszString++;
    }
    return FALSE;
}

Referenced by ShimLib_GetHookAPIs().

ShimLib_StringDuplicateA()

PCSTR ShimLib_StringDuplicateA

(

PCSTR

szString

)

Definition at line 67 of file shimlib.c.

{
    return ShimLib_StringNDuplicateA(szString, lstrlenA(szString) + 1);
}

Referenced by InitIgnoreFreeLibrary().

ShimLib_StringNDuplicateA()

PCSTR ShimLib_StringNDuplicateA	(	PCSTR	szString,
		SIZE_T	stringLengthIncludingNullTerm
	)

Definition at line 60 of file shimlib.c.

{
    PSTR NewString = ShimLib_ShimMalloc(stringLengthIncludingNullTerm);
    StringCchCopyA(NewString, stringLengthIncludingNullTerm, szString);
    return NewString;
}

Referenced by InitIgnoreFreeLibrary(), and ShimLib_StringDuplicateA().

Variable Documentation

g_ShimEngDebugLevel

ULONG g_ShimEngDebugLevel = 0xffffffff

Definition at line 25 of file shimlib.c.

Referenced by SeiDbgPrint(), and SeiInitDebugSupport().

g_ShimLib_Heap

HANDLE g_ShimLib_Heap

static

Definition at line 27 of file shimlib.c.

Referenced by ShimLib_Deinit(), ShimLib_Init(), ShimLib_ShimFree(), and ShimLib_ShimMalloc().

g_ShimLib_hInstance

HINSTANCE g_ShimLib_hInstance

static

Definition at line 26 of file shimlib.c.

Referenced by ShimLib_Init(), and ShimLib_Instance().

g_UsedShims

PSLIST_HEADER g_UsedShims

static

Definition at line 28 of file shimlib.c.

Referenced by ShimLib_GetHookAPIs(), ShimLib_Init(), and ShimLib_NotifyShims().