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Issue #24838: tarfile's ustar and gnu formats now correctly calculate name and 

link field limits for multibyte character encodings like utf-8.
This commit is contained in:
Lars Gustäbel 2016-04-19 08:43:17 +02:00
parent 472233ec83
commit 0f450abec4
3 changed files with 100 additions and 19 deletions
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29
Lib/tarfile.py
View File

@ -812,11 +812,11 @@ class TarInfo(object):
"""
info["magic"] = POSIX_MAGIC
if len(info["linkname"]) > LENGTH_LINK:
if len(info["linkname"].encode(encoding, errors)) > LENGTH_LINK:
raise ValueError("linkname is too long")
if len(info["name"]) > LENGTH_NAME:
info["prefix"], info["name"] = self._posix_split_name(info["name"])
if len(info["name"].encode(encoding, errors)) > LENGTH_NAME:
info["prefix"], info["name"] = self._posix_split_name(info["name"], encoding, errors)
return self._create_header(info, USTAR_FORMAT, encoding, errors)
@ -826,10 +826,10 @@ class TarInfo(object):
info["magic"] = GNU_MAGIC
buf = b""
if len(info["linkname"]) > LENGTH_LINK:
if len(info["linkname"].encode(encoding, errors)) > LENGTH_LINK:
buf += self._create_gnu_long_header(info["linkname"], GNUTYPE_LONGLINK, encoding, errors)
if len(info["name"]) > LENGTH_NAME:
if len(info["name"].encode(encoding, errors)) > LENGTH_NAME:
buf += self._create_gnu_long_header(info["name"], GNUTYPE_LONGNAME, encoding, errors)
return buf + self._create_header(info, GNU_FORMAT, encoding, errors)
@ -889,19 +889,20 @@ class TarInfo(object):
"""
return cls._create_pax_generic_header(pax_headers, XGLTYPE, "utf-8")
def _posix_split_name(self, name):
def _posix_split_name(self, name, encoding, errors):
"""Split a name longer than 100 chars into a prefix
and a name part.
"""
prefix = name[:LENGTH_PREFIX + 1]
while prefix and prefix[-1] != "/":
prefix = prefix[:-1]
name = name[len(prefix):]
prefix = prefix[:-1]
if not prefix or len(name) > LENGTH_NAME:
components = name.split("/")
for i in range(1, len(components)):
prefix = "/".join(components[:i])
name = "/".join(components[i:])
if len(prefix.encode(encoding, errors)) <= LENGTH_PREFIX and \
len(name.encode(encoding, errors)) <= LENGTH_NAME:
break
else:
raise ValueError("name is too long")
return prefix, name
@staticmethod

87
Lib/test/test_tarfile.py
View File

@ -1667,9 +1667,7 @@ class PaxWriteTest(GNUWriteTest):
tar.close()
class UstarUnicodeTest(unittest.TestCase):
format = tarfile.USTAR_FORMAT
class UnicodeTest:
def test_iso8859_1_filename(self):
self._test_unicode_filename("iso8859-1")
@ -1750,7 +1748,86 @@ class UstarUnicodeTest(unittest.TestCase):
tar.close()
class GNUUnicodeTest(UstarUnicodeTest):
class UstarUnicodeTest(UnicodeTest, unittest.TestCase):
format = tarfile.USTAR_FORMAT
# Test whether the utf-8 encoded version of a filename exceeds the 100
# bytes name field limit (every occurrence of '\xff' will be expanded to 2
# bytes).
def test_unicode_name1(self):
self._test_ustar_name("0123456789" * 10)
self._test_ustar_name("0123456789" * 10 + "0", ValueError)
self._test_ustar_name("0123456789" * 9 + "01234567\xff")
self._test_ustar_name("0123456789" * 9 + "012345678\xff", ValueError)
def test_unicode_name2(self):
self._test_ustar_name("0123456789" * 9 + "012345\xff\xff")
self._test_ustar_name("0123456789" * 9 + "0123456\xff\xff", ValueError)
# Test whether the utf-8 encoded version of a filename exceeds the 155
# bytes prefix + '/' + 100 bytes name limit.
def test_unicode_longname1(self):
self._test_ustar_name("0123456789" * 15 + "01234/" + "0123456789" * 10)
self._test_ustar_name("0123456789" * 15 + "0123/4" + "0123456789" * 10, ValueError)
self._test_ustar_name("0123456789" * 15 + "012\xff/" + "0123456789" * 10)
self._test_ustar_name("0123456789" * 15 + "0123\xff/" + "0123456789" * 10, ValueError)
def test_unicode_longname2(self):
self._test_ustar_name("0123456789" * 15 + "01\xff/2" + "0123456789" * 10, ValueError)
self._test_ustar_name("0123456789" * 15 + "01\xff\xff/" + "0123456789" * 10, ValueError)
def test_unicode_longname3(self):
self._test_ustar_name("0123456789" * 15 + "01\xff\xff/2" + "0123456789" * 10, ValueError)
self._test_ustar_name("0123456789" * 15 + "01234/" + "0123456789" * 9 + "01234567\xff")
self._test_ustar_name("0123456789" * 15 + "01234/" + "0123456789" * 9 + "012345678\xff", ValueError)
def test_unicode_longname4(self):
self._test_ustar_name("0123456789" * 15 + "01234/" + "0123456789" * 9 + "012345\xff\xff")
self._test_ustar_name("0123456789" * 15 + "01234/" + "0123456789" * 9 + "0123456\xff\xff", ValueError)
def _test_ustar_name(self, name, exc=None):
with tarfile.open(tmpname, "w", format=self.format, encoding="utf-8") as tar:
t = tarfile.TarInfo(name)
if exc is None:
tar.addfile(t)
else:
self.assertRaises(exc, tar.addfile, t)
if exc is None:
with tarfile.open(tmpname, "r") as tar:
for t in tar:
self.assertEqual(name, t.name)
break
# Test the same as above for the 100 bytes link field.
def test_unicode_link1(self):
self._test_ustar_link("0123456789" * 10)
self._test_ustar_link("0123456789" * 10 + "0", ValueError)
self._test_ustar_link("0123456789" * 9 + "01234567\xff")
self._test_ustar_link("0123456789" * 9 + "012345678\xff", ValueError)
def test_unicode_link2(self):
self._test_ustar_link("0123456789" * 9 + "012345\xff\xff")
self._test_ustar_link("0123456789" * 9 + "0123456\xff\xff", ValueError)
def _test_ustar_link(self, name, exc=None):
with tarfile.open(tmpname, "w", format=self.format, encoding="utf-8") as tar:
t = tarfile.TarInfo("foo")
t.linkname = name
if exc is None:
tar.addfile(t)
else:
self.assertRaises(exc, tar.addfile, t)
if exc is None:
with tarfile.open(tmpname, "r") as tar:
for t in tar:
self.assertEqual(name, t.linkname)
break
class GNUUnicodeTest(UnicodeTest, unittest.TestCase):
format = tarfile.GNU_FORMAT
@ -1768,7 +1845,7 @@ class GNUUnicodeTest(UstarUnicodeTest):
self.fail("unable to read bad GNU tar pax header")
class PAXUnicodeTest(UstarUnicodeTest):
class PAXUnicodeTest(UnicodeTest, unittest.TestCase):
format = tarfile.PAX_FORMAT

3
Misc/NEWS
View File

@ -107,6 +107,9 @@ Core and Builtins
Library
-------
- Issue #24838: tarfile's ustar and gnu formats now correctly calculate name
and link field limits for multibyte character encodings like utf-8.
- Issue #26657: Fix directory traversal vulnerability with http.server on
Windows. This fixes a regression that was introduced in 3.3.4rc1 and
3.4.0rc1. Based on patch by Philipp Hagemeister.