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37406b9d97
Python's tarfile module is not very careful about paths that step out of the target directory. We can be a bit better at little cost. This was reported in 2007[1], and has recently been publicised [2, for example]. We were informed of this bug in December 2021 by Luis Alberto López Alvar, but decided then that there were no circumstances under which this was a security concern. That is, if you can alter the backup files, you can already do worse things. But there is a case to guard against an administrator being tricked into trying to restore a file that isn't based on a real backup. [1] https://nvd.nist.gov/vuln/detail/CVE-2007-4559 [2] https://www.theregister.com/2022/09/22/python_vulnerability_tarfile/ BUG: https://bugzilla.samba.org/show_bug.cgi?id=15185 Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz> Reviewed-by: Andrew Bartlett <abartlet@samba.org> Autobuild-User(master): Andrew Bartlett <abartlet@samba.org> Autobuild-Date(master): Tue Oct 4 03:48:43 UTC 2022 on sn-devel-184
44 lines
1.5 KiB
Python
44 lines
1.5 KiB
Python
# Unix SMB/CIFS implementation.
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# Copyright (C) Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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from tarfile import ExtractError, TarInfo, TarFile as UnsafeTarFile
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class TarFile(UnsafeTarFile):
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"""This TarFile implementation is trying to ameliorate CVE-2007-4559,
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where tarfile.TarFiles can step outside of the target directory
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using '../../'.
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"""
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def extract(self, member, path="", set_attrs=True, *, numeric_owner=False):
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if isinstance(member, TarInfo):
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name = member.name
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else:
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name = member
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if '../' in name:
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raise ExtractError(f"'../' is not allowed in path '{name}'")
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if name.startswith('/'):
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raise ExtractError(f"path '{name}' should not start with '/'")
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super().extract(member, path, set_attrs=set_attrs,
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numeric_owner=numeric_owner)
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open = TarFile.open
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