memmod: fix import loading function usage

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

3 files changed, 4 insertions, 26 deletions

diff --git a/tun/wintun/memmod/memmod_windows.go b/tun/wintun/memmod/memmod_windows.go
index 13f28ef..b9d7783 100644
--- a/tun/wintun/memmod/memmod_windows.go
+++ b/tun/wintun/memmod/memmod_windows.go
@@ -313,7 +313,7 @@ func (module *Module) buildImportTable() error {
 	module.modules = make([]windows.Handle, 0, 16)
 	importDesc := (*IMAGE_IMPORT_DESCRIPTOR)(a2p(module.codeBase + uintptr(directory.VirtualAddress)))
 	for !isBadReadPtr(uintptr(unsafe.Pointer(importDesc)), unsafe.Sizeof(*importDesc)) && importDesc.Name != 0 {
-		handle, err := loadLibraryA((*byte)(a2p(module.codeBase + uintptr(importDesc.Name))))
+		handle, err := windows.LoadLibraryEx(windows.BytePtrToString((*byte)(a2p(module.codeBase + uintptr(importDesc.Name)))), 0, windows.LOAD_LIBRARY_SEARCH_SYSTEM32)
 		if err != nil {
 			return fmt.Errorf("Error loading module: %w", err)
 		}
@@ -328,10 +328,10 @@ func (module *Module) buildImportTable() error {
 		}
 		for *thunkRef != 0 {
 			if IMAGE_SNAP_BY_ORDINAL(*thunkRef) {
-				*funcRef, err = getProcAddress(handle, (*byte)(a2p(IMAGE_ORDINAL(*thunkRef))))
+				*funcRef, err = windows.GetProcAddressByOrdinal(handle, IMAGE_ORDINAL(*thunkRef))
 			} else {
 				thunkData := (*IMAGE_IMPORT_BY_NAME)(a2p(module.codeBase + *thunkRef))
-				*funcRef, err = getProcAddress(handle, &thunkData.Name[0])
+				*funcRef, err = windows.GetProcAddress(handle, windows.BytePtrToString(&thunkData.Name[0]))
 			}
 			if err != nil {
 				windows.FreeLibrary(handle)
diff --git a/tun/wintun/memmod/syscall_windows.go b/tun/wintun/memmod/syscall_windows.go
index beae415..0b29cb9 100644
--- a/tun/wintun/memmod/syscall_windows.go
+++ b/tun/wintun/memmod/syscall_windows.go
@@ -324,8 +324,6 @@ const (
 	DLL_PROCESS_DETACH = 0
 )
 
-//sys	loadLibraryA(libFileName *byte) (module windows.Handle, err error) = kernel32.LoadLibraryA
-//sys	getProcAddress(module windows.Handle, procName *byte) (addr uintptr, err error) = kernel32.GetProcAddress
 //sys	isBadReadPtr(addr uintptr, ucb uintptr) (ret bool) = kernel32.IsBadReadPtr
 
 type SYSTEM_INFO struct {
diff --git a/tun/wintun/memmod/zsyscall_windows.go b/tun/wintun/memmod/zsyscall_windows.go
index c56b650..6a5b76f 100644
--- a/tun/wintun/memmod/zsyscall_windows.go
+++ b/tun/wintun/memmod/zsyscall_windows.go
@@ -40,31 +40,11 @@ func errnoErr(e syscall.Errno) error {
 var (
 	modkernel32 = windows.NewLazySystemDLL("kernel32.dll")
 
-	procGetProcAddress = modkernel32.NewProc("GetProcAddress")
-	procIsBadReadPtr   = modkernel32.NewProc("IsBadReadPtr")
-	procLoadLibraryA   = modkernel32.NewProc("LoadLibraryA")
+	procIsBadReadPtr = modkernel32.NewProc("IsBadReadPtr")
 )
 
-func getProcAddress(module windows.Handle, procName *byte) (addr uintptr, err error) {
-	r0, _, e1 := syscall.Syscall(procGetProcAddress.Addr(), 2, uintptr(module), uintptr(unsafe.Pointer(procName)), 0)
-	addr = uintptr(r0)
-	if addr == 0 {
-		err = errnoErr(e1)
-	}
-	return
-}
-
 func isBadReadPtr(addr uintptr, ucb uintptr) (ret bool) {
 	r0, _, _ := syscall.Syscall(procIsBadReadPtr.Addr(), 2, uintptr(addr), uintptr(ucb), 0)
 	ret = r0 != 0
 	return
 }
-
-func loadLibraryA(libFileName *byte) (module windows.Handle, err error) {
-	r0, _, e1 := syscall.Syscall(procLoadLibraryA.Addr(), 1, uintptr(unsafe.Pointer(libFileName)), 0, 0)
-	module = windows.Handle(r0)
-	if module == 0 {
-		err = errnoErr(e1)
-	}
-	return
-}