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gh-127987: Ensure that directories are not renamed during tar.TarFile.extractall() #134628

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38 changes: 27 additions & 11 deletions Lib/tarfile.py
Original file line number Diff line number Diff line change
Expand Up @@ -2389,20 +2389,34 @@ def extractall(self, path=".", members=None, *, numeric_owner=False,
tarinfo = self._get_extract_tarinfo(member, filter_function, path)
if tarinfo is None:
continue
self._extract_one(tarinfo, path, set_attrs=not tarinfo.isdir(),
numeric_owner=numeric_owner)
if tarinfo.isdir():
# For directories, delay setting attributes until later,
# since permissions can interfere with extraction and
# extracting contents can reset mtime.
directories.append(tarinfo)
self._extract_one(tarinfo, path, set_attrs=not tarinfo.isdir(),
numeric_owner=numeric_owner)
# We also the keep the original inode and device, to detect
# if it was changed during extraction.
dirpath = os.path.join(path, tarinfo.name)
dirpath = self._transform_destination_path(dirpath)
targetstat = os.stat(dirpath, follow_symlinks=False)
directories.append((tarinfo, dirpath, targetstat.st_ino,
targetstat.st_dev))

# Reverse sort directories.
directories.sort(key=lambda a: a.name, reverse=True)
directories.sort(key=lambda a: a[0].name, reverse=True)

# Set correct owner, mtime and filemode on directories.
for tarinfo in directories:
dirpath = os.path.join(path, tarinfo.name)
for tarinfo, dirpath, original_ino, original_dev in directories:
dirstat = os.stat(dirpath, follow_symlinks=False)
if (dirstat.st_ino != original_ino or
dirstat.st_dev != original_dev or
not stat.S_ISDIR(dirstat.st_mode) # just in case the inode was reused
):
self._dbg(1, "tarfile: Directory renamed before its " \
"attributes could be extracted %r" % dirpath)
continue

try:
self.chown(tarinfo, dirpath, numeric_owner=numeric_owner)
self.utime(tarinfo, dirpath)
Expand Down Expand Up @@ -2516,16 +2530,18 @@ def extractfile(self, member):
# blkdev, etc.), return None instead of a file object.
return None

def _transform_destination_path(self, targetpath):
# Build the destination pathname, replacing
# forward slashes to platform specific separators.
targetpath = targetpath.rstrip("/")
return targetpath.replace("/", os.sep)

def _extract_member(self, tarinfo, targetpath, set_attrs=True,
numeric_owner=False):
"""Extract the TarInfo object tarinfo to a physical
file called targetpath.
"""
# Fetch the TarInfo object for the given name
# and build the destination pathname, replacing
# forward slashes to platform specific separators.
targetpath = targetpath.rstrip("/")
targetpath = targetpath.replace("/", os.sep)
targetpath = self._transform_destination_path(targetpath)

# Create all upper directories.
upperdirs = os.path.dirname(targetpath)
Expand Down
25 changes: 25 additions & 0 deletions Lib/test/test_tarfile.py
Original file line number Diff line number Diff line change
Expand Up @@ -2715,6 +2715,31 @@ def test_useful_error_message_when_modules_missing(self):
str(excinfo.exception),
)

@unittest.skipUnless(os_helper.can_symlink(), 'requires symlink support')
@unittest.skipUnless(hasattr(os, 'chmod'), "missing os.chmod")
@unittest.mock.patch('os.chmod')
def test_deferred_directory_attributes_update(self, mock_chmod):
# Regression test for gh-127987: setting attributes on arbitrary files
tempdir = os.path.join(TEMPDIR, 'test127987')
def mock_chmod_side_effect(path, mode, **kwargs):
target_path = os.path.realpath(path)
if os.path.commonpath([target_path, tempdir]) != tempdir:
raise Exception("should not try to chmod anything outside the destination", target_path)
mock_chmod.side_effect = mock_chmod_side_effect

outside_tree_dir = os.path.join(TEMPDIR, 'outside_tree_dir')
with ArchiveMaker() as arc:
arc.add('x', symlink_to='.')
arc.add('x', type=tarfile.DIRTYPE, mode='?rwsrwsrwt')
arc.add('x', symlink_to=outside_tree_dir)

os.makedirs(outside_tree_dir)
try:
arc.open().extractall(path=tempdir, filter='tar')
finally:
os_helper.rmtree(outside_tree_dir)
os_helper.rmtree(tempdir)


class CommandLineTest(unittest.TestCase):

Expand Down
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