diff --git a/stacker/util.py b/stacker/util.py index dc9e1394..eaf29a22 100644 --- a/stacker/util.py +++ b/stacker/util.py @@ -491,7 +491,26 @@ class TarExtractor(Extractor): def extract(self, destination): """Extract the archive.""" with tarfile.open(self.archive, 'r:') as tar: - tar.extractall(path=destination) + def is_within_directory(directory, target): + + abs_directory = os.path.abspath(directory) + abs_target = os.path.abspath(target) + + prefix = os.path.commonprefix([abs_directory, abs_target]) + + return prefix == abs_directory + + def safe_extract(tar, path=".", members=None, *, numeric_owner=False): + + for member in tar.getmembers(): + member_path = os.path.join(path, member.name) + if not is_within_directory(path, member_path): + raise Exception("Attempted Path Traversal in Tar File") + + tar.extractall(path, members, numeric_owner=numeric_owner) + + + safe_extract(tar, path=destination) @staticmethod def extension(): @@ -505,7 +524,26 @@ class TarGzipExtractor(Extractor): def extract(self, destination): """Extract the archive.""" with tarfile.open(self.archive, 'r:gz') as tar: - tar.extractall(path=destination) + def is_within_directory(directory, target): + + abs_directory = os.path.abspath(directory) + abs_target = os.path.abspath(target) + + prefix = os.path.commonprefix([abs_directory, abs_target]) + + return prefix == abs_directory + + def safe_extract(tar, path=".", members=None, *, numeric_owner=False): + + for member in tar.getmembers(): + member_path = os.path.join(path, member.name) + if not is_within_directory(path, member_path): + raise Exception("Attempted Path Traversal in Tar File") + + tar.extractall(path, members, numeric_owner=numeric_owner) + + + safe_extract(tar, path=destination) @staticmethod def extension():