DllSecur.c

/* DllSecur.c -- DLL loading security
2023-12-03 : Igor Pavlov : Public domain */

#include "Precomp.h"

#ifdef _WIN32

#include "7zWindows.h"

#include "DllSecur.h"

#ifndef UNDER_CE

Z7_DIAGNOSTIC_IGNORE_CAST_FUNCTION

typedef BOOL (WINAPI *Func_SetDefaultDllDirectories)(DWORD DirectoryFlags);

#define MY_LOAD_LIBRARY_SEARCH_USER_DIRS 0x400
#define MY_LOAD_LIBRARY_SEARCH_SYSTEM32  0x800

#define DELIM "\0"

static const char * const g_Dlls =
         "userenv"
  DELIM  "setupapi"
  DELIM  "apphelp"
  DELIM  "propsys"
  DELIM  "dwmapi"
  DELIM  "cryptbase"
  DELIM  "oleacc"
  DELIM  "clbcatq"
  DELIM  "version"
  #ifndef _CONSOLE
  DELIM  "uxtheme"
  #endif
  DELIM;

#endif

#ifdef __clang__
  #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
#endif
#if defined (_MSC_VER) && _MSC_VER >= 1900
// sysinfoapi.h: kit10: GetVersion was declared deprecated
#pragma warning(disable : 4996)
#endif

#define IF_NON_VISTA_SET_DLL_DIRS_AND_RETURN \
    if ((UInt16)GetVersion() != 6) { \
      const \
       Func_SetDefaultDllDirectories setDllDirs = \
      (Func_SetDefaultDllDirectories) Z7_CAST_FUNC_C GetProcAddress(GetModuleHandle(TEXT("kernel32.dll")), \
           "SetDefaultDllDirectories"); \
      if (setDllDirs) if (setDllDirs(MY_LOAD_LIBRARY_SEARCH_SYSTEM32 | MY_LOAD_LIBRARY_SEARCH_USER_DIRS)) return; }

void My_SetDefaultDllDirectories(void)
{
  #ifndef UNDER_CE
  IF_NON_VISTA_SET_DLL_DIRS_AND_RETURN
  #endif
}


void LoadSecurityDlls(void)
{
  #ifndef UNDER_CE
  // at Vista (ver 6.0) : CoCreateInstance(CLSID_ShellLink, ...) doesn't work after SetDefaultDllDirectories() : Check it ???
  IF_NON_VISTA_SET_DLL_DIRS_AND_RETURN
  {
    wchar_t buf[MAX_PATH + 100];
    const char *dll;
    unsigned pos = GetSystemDirectoryW(buf, MAX_PATH + 2);
    if (pos == 0 || pos > MAX_PATH)
      return;
    if (buf[pos - 1] != '\\')
      buf[pos++] = '\\';
    for (dll = g_Dlls; *dll != 0;)
    {
      wchar_t *dest = &buf[pos];
      for (;;)
      {
        const char c = *dll++;
        if (c == 0)
          break;
        *dest++ = (Byte)c;
      }
      dest[0] = '.';
      dest[1] = 'd';
      dest[2] = 'l';
      dest[3] = 'l';
      dest[4] = 0;
      // lstrcatW(buf, L".dll");
      LoadLibraryExW(buf, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
    }
  }
  #endif
}

#endif // _WIN32