ncv/ncval_test.py

   1
   2 import os
   3 import shutil
   4 import subprocess
   5 import tempfile
   6 import unittest
   7
   8 import ncval_stubout
   9
  10
  11 def write_file(filename, data):
  12     fh = open(filename, "w")
  13     try:
  14         fh.write(data)
  15     finally:
  16         fh.close()
  17
  18
  19 def read_file(filename):
  20     fh = open(filename, "r")
  21     try:
  22         return fh.read()
  23     finally:
  24         fh.close()
  25
  26
  27 class TempDirTestCase(unittest.TestCase):
  28
  29     def setUp(self):
  30         self._on_teardown = []
  31
  32     def make_temp_dir(self):
  33         temp_dir = tempfile.mkdtemp(prefix="tmp-%s-" % self.__class__.__name__)
  34         def tear_down():
  35             shutil.rmtree(temp_dir)
  36         self._on_teardown.append(tear_down)
  37         return temp_dir
  38
  39     def tearDown(self):
  40         for func in reversed(self._on_teardown):
  41             func()
  42
  43
  44 class NcValTest(TempDirTestCase):
  45
  46     def assertEquals(self, x, y):
  47         if x != y:
  48             if type(x) == str and type(y) == str:
  49                 raise AssertionError('"%s"\n!="%s"' % (x, y))
  50             raise AssertionError("%r != %r" % (x, y))
  51
  52     def _get_errors(self, obj_file):
  53         proc = subprocess.Popen(["ncval", obj_file], stdout=subprocess.PIPE)
  54         lines = [line for line in proc.stdout
  55                  if line.startswith("VALIDATOR")]
  56         self.assertEquals(proc.wait(), 0)
  57         return lines
  58
  59     def test_stub_out(self):
  60         asm_file = os.path.join(self.make_temp_dir(), "example.S")
  61         obj_file = os.path.join(self.make_temp_dir(), "example")
  62         write_file(asm_file, """
  63         .global _start
  64 _start:
  65         jmp 0x12345678
  66         jmp *%ecx
  67         mov %fs,%dx
  68         ret
  69         int $0x80
  70 """)
  71         subprocess.check_call(["nacl-gcc", "-nostartfiles", asm_file,
  72                                "-o", obj_file])
  73         self.assertEquals("".join(self._get_errors(obj_file)), """\
  74 VALIDATOR: 00010000 (00001000:?): Jump target out of range
  75 VALIDATOR: 00010005 (00001005:2): Unsafe indirect jump
  76 VALIDATOR: 00010007 (00001007:3): Bad prefix
  77 VALIDATOR: 00010007 (00001007:3): Illegal instruction
  78 VALIDATOR: 0001000a (0000100a:1): Illegal instruction
  79 VALIDATOR: 0001000b (0000100b:2): Illegal instruction
  80 """)
  81         ncval_stubout.main([obj_file])
  82         # Can't stub out bad jumps yet
  83         self.assertEquals("".join(self._get_errors(obj_file)), """\
  84 VALIDATOR: 00010000 (00001000:?): Jump target out of range
  85 """)
  86
  87     def test_multiple_sections(self):
  88         # Check that we handle file indexes correctly in the presence
  89         # of multiple ELF sections.
  90         asm_file = os.path.join(self.make_temp_dir(), "example.S")
  91         obj_file = os.path.join(self.make_temp_dir(), "example")
  92         write_file(asm_file, """
  93         .global _start
  94 _start:
  95         nop
  96         nop
  97         .section .fini, "x", @progbits
  98         ret
  99 """)
 100         subprocess.check_call(["nacl-gcc", "-nostartfiles", asm_file,
 101                                "-o", obj_file])
 102         self.assertNotEquals(self._get_errors(obj_file), [])
 103         ncval_stubout.main([obj_file])
 104         self.assertEquals(self._get_errors(obj_file), [])
 105
 106
 107 class JumpRewriterTest(TempDirTestCase):
 108
 109     def _assemble(self, asm_source):
 110         asm_file = os.path.join(self.make_temp_dir(), "foo.S")
 111         obj_file = os.path.join(self.make_temp_dir(), "foo.o")
 112         write_file(asm_file, asm_source)
 113         subprocess.check_call(["gcc", "-c", asm_file, "-o", obj_file])
 114         return obj_file
 115
 116     def _disassemble(self, obj_file):
 117         proc = subprocess.Popen(["objdump", "-d", obj_file],
 118                                 stdout=subprocess.PIPE)
 119         return proc.communicate()[0]
 120
 121     def test_rewriting(self):
 122         original = """
 123         // Instructions to be rewritten
 124         nop; nop; nop
 125         jmp *%eax
 126         nop; nop; nop
 127         jmp *%ebx
 128         nop; nop; nop
 129         jmp *%ecx
 130         nop; nop; nop
 131         jmp *%edx
 132
 133         nop; nop; nop
 134         call *%eax
 135         nop; nop; nop
 136         call *%ebx
 137         nop; nop; nop
 138         call *%ecx
 139         nop; nop; nop
 140         call *%edx
 141 """
 142         rewritten = """
 143         and $0xffffffe0, %eax
 144         jmp *%eax
 145         and $0xffffffe0, %ebx
 146         jmp *%ebx
 147         and $0xffffffe0, %ecx
 148         jmp *%ecx
 149         and $0xffffffe0, %edx
 150         jmp *%edx
 151
 152         and $0xffffffe0, %eax
 153         call *%eax
 154         and $0xffffffe0, %ebx
 155         call *%ebx
 156         and $0xffffffe0, %ecx
 157         call *%ecx
 158         and $0xffffffe0, %edx
 159         call *%edx
 160 """
 161         leave_alone = """
 162         // These should be left alone
 163         nop; nop; nop
 164         jmp 0x12345678
 165         mov $123, %eax
 166 """
 167         obj_file = self._assemble(original + leave_alone)
 168         obj_file_expect = self._assemble(rewritten + leave_alone)
 169         subprocess.check_call(["ncrewrite", obj_file])
 170         if read_file(obj_file) != read_file(obj_file_expect):
 171             raise Exception("Unexpected output:\n%s\nExpected:\n%s" %
 172                             (self._disassemble(obj_file),
 173                              self._disassemble(obj_file_expect)))
 174
 175     def test_rewriting_missing_nops(self):
 176         input_data = """
 177         // Not enough preceding nops to rewrite
 178         nop; nop
 179         jmp *%ecx
 180 """
 181         obj_file = self._assemble(input_data * 2)
 182         original = read_file(obj_file)
 183         proc = subprocess.Popen(["ncrewrite", obj_file], stderr=subprocess.PIPE)
 184         stderr = proc.communicate()[1]
 185         self.assertEquals(stderr,
 186                           "00000002: missing nops\n"
 187                           "00000006: missing nops\n")
 188         self.assertEquals(proc.wait(), 0)
 189         # Object file should not have been changed.
 190         self.assertEquals(original, read_file(obj_file))
 191
 192
 193 if __name__ == "__main__":
 194     unittest.main()