78 lines
2.5 KiB
Python
78 lines
2.5 KiB
Python
"""
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Safe version of tarfile.extractall which does not extract any files that would
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be, or symlink to a file that is, outside of the directory extracted in.
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Adapted from:
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http://stackoverflow.com/questions/10060069/safely-extract-zip-or-tar-using-python
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"""
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import logging
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from os.path import join as joinpath
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from os.path import abspath, dirname, realpath
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from django.conf import settings
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from django.core.exceptions import SuspiciousOperation
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log = logging.getLogger(__name__)
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def resolved(rpath):
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"""
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Returns the canonical absolute path of `rpath`.
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"""
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return realpath(abspath(rpath))
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def _is_bad_path(path, base):
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"""
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Is (the canonical absolute path of) `path` outside `base`?
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"""
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return not resolved(joinpath(base, path)).startswith(base)
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def _is_bad_link(info, base):
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"""
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Does the file sym- or hard-link to files outside `base`?
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"""
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# Links are interpreted relative to the directory containing the link
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tip = resolved(joinpath(base, dirname(info.name)))
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return _is_bad_path(info.linkname, base=tip)
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def safemembers(members, base):
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"""
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Check that all elements of a tar file are safe.
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"""
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base = resolved(base)
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# check that we're not trying to import outside of the github_repo_root
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if not base.startswith(resolved(settings.GITHUB_REPO_ROOT)):
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raise SuspiciousOperation("Attempted to import course outside of data dir")
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for finfo in members:
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if _is_bad_path(finfo.name, base): # lint-amnesty, pylint: disable=no-else-raise
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log.debug("File %r is blocked (illegal path)", finfo.name)
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raise SuspiciousOperation("Illegal path")
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elif finfo.issym() and _is_bad_link(finfo, base):
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log.debug("File %r is blocked: Hard link to %r", finfo.name, finfo.linkname)
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raise SuspiciousOperation("Hard link")
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elif finfo.islnk() and _is_bad_link(finfo, base):
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log.debug("File %r is blocked: Symlink to %r", finfo.name,
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finfo.linkname)
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raise SuspiciousOperation("Symlink")
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elif finfo.isdev():
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log.debug("File %r is blocked: FIFO, device or character file",
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finfo.name)
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raise SuspiciousOperation("Dev file")
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return members
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def safetar_extractall(tar_file, path=".", members=None): # pylint: disable=unused-argument
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"""
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Safe version of `tar_file.extractall()`.
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"""
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path = str(path)
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return tar_file.extractall(path, safemembers(tar_file, path))
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