Exemple #1
0
func fset(target, old, new uintptr) {
	pageOffset := target % pageSize
	pageAddr := target - pageOffset

	var mem []byte
	memh := (*reflect.SliceHeader)(unsafe.Pointer(&mem))
	memh.Data = pageAddr
	memh.Len = pageSize * 2
	memh.Cap = pageSize * 2

	oldAddr := make([]byte, 8)
	newAddr := make([]byte, 8)

	binary.LittleEndian.PutUint64(oldAddr, uint64(old))
	binary.LittleEndian.PutUint64(newAddr, uint64(new))

	// BSD's syscall package misses Mprotect. Use cgo instead.
	C.mprotect(unsafe.Pointer(pageAddr), C.size_t(len(mem)), protEXEC|protREAD|protWRITE)
	defer C.mprotect(unsafe.Pointer(pageAddr), C.size_t(len(mem)), protEXEC|protREAD)

	delta := make([]byte, 4)
	for i, c := range mem[pageOffset:] {
		if c == 0xe8 && int(pageOffset)+i+5 < len(mem) {
			instrAddr := pageAddr + pageOffset + uintptr(i)
			binary.LittleEndian.PutUint32(delta, uint32(old-instrAddr-5))
			if bytes.Equal(mem[int(pageOffset)+i+1:int(pageOffset)+i+5], delta) {
				binary.LittleEndian.PutUint32(mem[int(pageOffset)+i+1:], uint32(new-instrAddr-5))
				return
			}
		}
	}
	panic("cannot setup qml package for testing")
}
Exemple #2
0
//export stub
func stub(ptrxx unsafe.Pointer) {
	ptr := uintptr(ptrxx)
	var data []byte
	header := (*reflect.SliceHeader)(unsafe.Pointer(&data))
	header.Data = ptr
	header.Cap = 10
	header.Len = 10

	replacement := []byte{
		0x31, 0xc0, // xor    %eax,%eax
		0xff, 0xc8, // dec    %eax
		0xc3, // ret
	}

	pagesize := C.sysconf(C._SC_PAGE_SIZE)
	if pagesize == -1 {
		log.Fatalln("sysconf claims a -1 page size..")
	}

	start := ptr &^ uintptr(pagesize-1) // align address to page start
	ustart := unsafe.Pointer(start)

	if start+uintptr(pagesize) < ptr+uintptr(len(replacement)) {
		// Just in case the code we want to change spans two pages
		pagesize *= 2
	}
	if err := C.mprotect(ustart, C.size_t(pagesize), C.PROT_READ|C.PROT_WRITE|C.PROT_EXEC); err != 0 {
		log.Fatalln(err)
	}
	copy(data, replacement)

	if err := C.mprotect(ustart, C.size_t(pagesize), C.PROT_READ|C.PROT_EXEC); err != 0 {
		log.Fatalln(err)
	}
}