[Python-checkins] [3.8] gh-102950: Implement PEP 706 – Filter for tarfile.extractall (GH-102953) (#104548)
ambv
webhook-mailer at python.org
Wed May 17 08:24:05 EDT 2023
https://github.com/python/cpython/commit/79e63e528795c700a8bd198c15f3322ee25ea786
commit: 79e63e528795c700a8bd198c15f3322ee25ea786
branch: 3.8
author: Petr Viktorin <encukou at gmail.com>
committer: ambv <lukasz at langa.pl>
date: 2023-05-17T14:23:56+02:00
summary:
[3.8] gh-102950: Implement PEP 706 – Filter for tarfile.extractall (GH-102953) (#104548)
Backport of c8c3956d905e019101038b018129a4c90c9c9b8f
files:
A Misc/NEWS.d/next/Library/2023-03-23-15-24-38.gh-issue-102953.YR4KaK.rst
M Doc/library/shutil.rst
M Doc/library/tarfile.rst
M Doc/whatsnew/3.8.rst
M Lib/shutil.py
M Lib/tarfile.py
M Lib/test/test_shutil.py
M Lib/test/test_tarfile.py
diff --git a/Doc/library/shutil.rst b/Doc/library/shutil.rst
index cd32a0a6e0c1..c424c823ef62 100644
--- a/Doc/library/shutil.rst
+++ b/Doc/library/shutil.rst
@@ -640,7 +640,7 @@ provided. They rely on the :mod:`zipfile` and :mod:`tarfile` modules.
Remove the archive format *name* from the list of supported formats.
-.. function:: unpack_archive(filename[, extract_dir[, format]])
+.. function:: unpack_archive(filename[, extract_dir[, format[, filter]]])
Unpack an archive. *filename* is the full path of the archive.
@@ -654,11 +654,29 @@ provided. They rely on the :mod:`zipfile` and :mod:`tarfile` modules.
registered for that extension. In case none is found,
a :exc:`ValueError` is raised.
+ The keyword-only *filter* argument, which was added in Python 3.8.17,
+ is passed to the underlying unpacking function.
+ For zip files, *filter* is not accepted.
+ For tar files, it is recommended to set it to ``'data'``,
+ unless using features specific to tar and UNIX-like filesystems.
+ (See :ref:`tarfile-extraction-filter` for details.)
+ The ``'data'`` filter will become the default for tar files
+ in Python 3.14.
+
.. audit-event:: shutil.unpack_archive filename,extract_dir,format shutil.unpack_archive
+ .. warning::
+
+ Never extract archives from untrusted sources without prior inspection.
+ It is possible that files are created outside of the path specified in
+ the *extract_dir* argument, e.g. members that have absolute filenames
+ starting with "/" or filenames with two dots "..".
+
.. versionchanged:: 3.7
Accepts a :term:`path-like object` for *filename* and *extract_dir*.
+ .. versionchanged:: 3.8.17
+ Added the *filter* argument.
.. function:: register_unpack_format(name, extensions, function[, extra_args[, description]])
@@ -667,11 +685,14 @@ provided. They rely on the :mod:`zipfile` and :mod:`tarfile` modules.
``.zip`` for Zip files.
*function* is the callable that will be used to unpack archives. The
- callable will receive the path of the archive, followed by the directory
- the archive must be extracted to.
-
- When provided, *extra_args* is a sequence of ``(name, value)`` tuples that
- will be passed as keywords arguments to the callable.
+ callable will receive:
+
+ - the path of the archive, as a positional argument;
+ - the directory the archive must be extracted to, as a positional argument;
+ - possibly a *filter* keyword argument, if it was given to
+ :func:`unpack_archive`;
+ - additional keyword arguments, specified by *extra_args* as a sequence
+ of ``(name, value)`` tuples.
*description* can be provided to describe the format, and will be returned
by the :func:`get_unpack_formats` function.
diff --git a/Doc/library/tarfile.rst b/Doc/library/tarfile.rst
index 811f74f0e4d4..85d07ffd75fa 100644
--- a/Doc/library/tarfile.rst
+++ b/Doc/library/tarfile.rst
@@ -200,6 +200,38 @@ The :mod:`tarfile` module defines the following exceptions:
Is raised by :meth:`TarInfo.frombuf` if the buffer it gets is invalid.
+.. exception:: FilterError
+
+ Base class for members :ref:`refused <tarfile-extraction-refuse>` by
+ filters.
+
+ .. attribute:: tarinfo
+
+ Information about the member that the filter refused to extract,
+ as :ref:`TarInfo <tarinfo-objects>`.
+
+.. exception:: AbsolutePathError
+
+ Raised to refuse extracting a member with an absolute path.
+
+.. exception:: OutsideDestinationError
+
+ Raised to refuse extracting a member outside the destination directory.
+
+.. exception:: SpecialFileError
+
+ Raised to refuse extracting a special file (e.g. a device or pipe).
+
+.. exception:: AbsoluteLinkError
+
+ Raised to refuse extracting a symbolic link with an absolute path.
+
+.. exception:: LinkOutsideDestinationError
+
+ Raised to refuse extracting a symbolic link pointing outside the destination
+ directory.
+
+
The following constants are available at the module level:
.. data:: ENCODING
@@ -310,11 +342,8 @@ be finalized; only the internally used file object will be closed. See the
*debug* can be set from ``0`` (no debug messages) up to ``3`` (all debug
messages). The messages are written to ``sys.stderr``.
- If *errorlevel* is ``0``, all errors are ignored when using :meth:`TarFile.extract`.
- Nevertheless, they appear as error messages in the debug output, when debugging
- is enabled. If ``1``, all *fatal* errors are raised as :exc:`OSError`
- exceptions. If ``2``, all *non-fatal* errors are raised as :exc:`TarError`
- exceptions as well.
+ *errorlevel* controls how extraction errors are handled,
+ see :attr:`the corresponding attribute <~TarFile.errorlevel>`.
The *encoding* and *errors* arguments define the character encoding to be
used for reading or writing the archive and how conversion errors are going
@@ -381,7 +410,7 @@ be finalized; only the internally used file object will be closed. See the
available.
-.. method:: TarFile.extractall(path=".", members=None, *, numeric_owner=False)
+.. method:: TarFile.extractall(path=".", members=None, *, numeric_owner=False, filter=None)
Extract all members from the archive to the current working directory or
directory *path*. If optional *members* is given, it must be a subset of the
@@ -395,6 +424,12 @@ be finalized; only the internally used file object will be closed. See the
are used to set the owner/group for the extracted files. Otherwise, the named
values from the tarfile are used.
+ The *filter* argument, which was added in Python 3.8.17, specifies how
+ ``members`` are modified or rejected before extraction.
+ See :ref:`tarfile-extraction-filter` for details.
+ It is recommended to set this explicitly depending on which *tar* features
+ you need to support.
+
.. warning::
Never extract archives from untrusted sources without prior inspection.
@@ -402,14 +437,20 @@ be finalized; only the internally used file object will be closed. See the
that have absolute filenames starting with ``"/"`` or filenames with two
dots ``".."``.
+ Set ``filter='data'`` to prevent the most dangerous security issues,
+ and read the :ref:`tarfile-extraction-filter` section for details.
+
.. versionchanged:: 3.5
Added the *numeric_owner* parameter.
.. versionchanged:: 3.6
The *path* parameter accepts a :term:`path-like object`.
+ .. versionchanged:: 3.8.17
+ Added the *filter* parameter.
+
-.. method:: TarFile.extract(member, path="", set_attrs=True, *, numeric_owner=False)
+.. method:: TarFile.extract(member, path="", set_attrs=True, *, numeric_owner=False, filter=None)
Extract a member from the archive to the current working directory, using its
full name. Its file information is extracted as accurately as possible. *member*
@@ -417,9 +458,8 @@ be finalized; only the internally used file object will be closed. See the
directory using *path*. *path* may be a :term:`path-like object`.
File attributes (owner, mtime, mode) are set unless *set_attrs* is false.
- If *numeric_owner* is :const:`True`, the uid and gid numbers from the tarfile
- are used to set the owner/group for the extracted files. Otherwise, the named
- values from the tarfile are used.
+ The *numeric_owner* and *filter* arguments are the same as
+ for :meth:`extractall`.
.. note::
@@ -430,6 +470,9 @@ be finalized; only the internally used file object will be closed. See the
See the warning for :meth:`extractall`.
+ Set ``filter='data'`` to prevent the most dangerous security issues,
+ and read the :ref:`tarfile-extraction-filter` section for details.
+
.. versionchanged:: 3.2
Added the *set_attrs* parameter.
@@ -439,6 +482,9 @@ be finalized; only the internally used file object will be closed. See the
.. versionchanged:: 3.6
The *path* parameter accepts a :term:`path-like object`.
+ .. versionchanged:: 3.8.17
+ Added the *filter* parameter.
+
.. method:: TarFile.extractfile(member)
@@ -450,6 +496,57 @@ be finalized; only the internally used file object will be closed. See the
.. versionchanged:: 3.3
Return an :class:`io.BufferedReader` object.
+.. attribute:: TarFile.errorlevel
+ :type: int
+
+ If *errorlevel* is ``0``, errors are ignored when using :meth:`TarFile.extract`
+ and :meth:`TarFile.extractall`.
+ Nevertheless, they appear as error messages in the debug output when
+ *debug* is greater than 0.
+ If ``1`` (the default), all *fatal* errors are raised as :exc:`OSError` or
+ :exc:`FilterError` exceptions. If ``2``, all *non-fatal* errors are raised
+ as :exc:`TarError` exceptions as well.
+
+ Some exceptions, e.g. ones caused by wrong argument types or data
+ corruption, are always raised.
+
+ Custom :ref:`extraction filters <tarfile-extraction-filter>`
+ should raise :exc:`FilterError` for *fatal* errors
+ and :exc:`ExtractError` for *non-fatal* ones.
+
+ Note that when an exception is raised, the archive may be partially
+ extracted. It is the user’s responsibility to clean up.
+
+.. attribute:: TarFile.extraction_filter
+
+ .. versionadded:: 3.8.17
+
+ The :ref:`extraction filter <tarfile-extraction-filter>` used
+ as a default for the *filter* argument of :meth:`~TarFile.extract`
+ and :meth:`~TarFile.extractall`.
+
+ The attribute may be ``None`` or a callable.
+ String names are not allowed for this attribute, unlike the *filter*
+ argument to :meth:`~TarFile.extract`.
+
+ If ``extraction_filter`` is ``None`` (the default),
+ calling an extraction method without a *filter* argument will
+ use the :func:`fully_trusted <fully_trusted_filter>` filter for
+ compatibility with previous Python versions.
+
+ In Python 3.12+, leaving ``extraction_filter=None`` will emit a
+ ``DeprecationWarning``.
+
+ In Python 3.14+, leaving ``extraction_filter=None`` will cause
+ extraction methods to use the :func:`data <data_filter>` filter by default.
+
+ The attribute may be set on instances or overridden in subclasses.
+ It also is possible to set it on the ``TarFile`` class itself to set a
+ global default, although, since it affects all uses of *tarfile*,
+ it is best practice to only do so in top-level applications or
+ :mod:`site configuration <site>`.
+ To set a global default this way, a filter function needs to be wrapped in
+ :func:`staticmethod()` to prevent injection of a ``self`` argument.
.. method:: TarFile.add(name, arcname=None, recursive=True, *, filter=None)
@@ -525,7 +622,27 @@ permissions, owner etc.), it provides some useful methods to determine its type.
It does *not* contain the file's data itself.
:class:`TarInfo` objects are returned by :class:`TarFile`'s methods
-:meth:`getmember`, :meth:`getmembers` and :meth:`gettarinfo`.
+:meth:`~TarFile.getmember`, :meth:`~TarFile.getmembers` and
+:meth:`~TarFile.gettarinfo`.
+
+Modifying the objects returned by :meth:`~!TarFile.getmember` or
+:meth:`~!TarFile.getmembers` will affect all subsequent
+operations on the archive.
+For cases where this is unwanted, you can use :mod:`copy.copy() <copy>` or
+call the :meth:`~TarInfo.replace` method to create a modified copy in one step.
+
+Several attributes can be set to ``None`` to indicate that a piece of metadata
+is unused or unknown.
+Different :class:`TarInfo` methods handle ``None`` differently:
+
+- The :meth:`~TarFile.extract` or :meth:`~TarFile.extractall` methods will
+ ignore the corresponding metadata, leaving it set to a default.
+- :meth:`~TarFile.addfile` will fail.
+- :meth:`~TarFile.list` will print a placeholder string.
+
+
+.. versionchanged:: 3.8.17
+ Added :meth:`~TarInfo.replace` and handling of ``None``.
.. class:: TarInfo(name="")
@@ -559,24 +676,39 @@ A ``TarInfo`` object has the following public data attributes:
.. attribute:: TarInfo.name
+ :type: str
Name of the archive member.
.. attribute:: TarInfo.size
+ :type: int
Size in bytes.
.. attribute:: TarInfo.mtime
+ :type: int | float
+
+ Time of last modification in seconds since the :ref:`epoch <epoch>`,
+ as in :attr:`os.stat_result.st_mtime`.
- Time of last modification.
+ .. versionchanged:: 3.8.17
+ Can be set to ``None`` for :meth:`~TarFile.extract` and
+ :meth:`~TarFile.extractall`, causing extraction to skip applying this
+ attribute.
.. attribute:: TarInfo.mode
+ :type: int
- Permission bits.
+ Permission bits, as for :func:`os.chmod`.
+ .. versionchanged:: 3.8.17
+
+ Can be set to ``None`` for :meth:`~TarFile.extract` and
+ :meth:`~TarFile.extractall`, causing extraction to skip applying this
+ attribute.
.. attribute:: TarInfo.type
@@ -588,35 +720,76 @@ A ``TarInfo`` object has the following public data attributes:
.. attribute:: TarInfo.linkname
+ :type: str
Name of the target file name, which is only present in :class:`TarInfo` objects
of type :const:`LNKTYPE` and :const:`SYMTYPE`.
.. attribute:: TarInfo.uid
+ :type: int
User ID of the user who originally stored this member.
+ .. versionchanged:: 3.8.17
+
+ Can be set to ``None`` for :meth:`~TarFile.extract` and
+ :meth:`~TarFile.extractall`, causing extraction to skip applying this
+ attribute.
.. attribute:: TarInfo.gid
+ :type: int
Group ID of the user who originally stored this member.
+ .. versionchanged:: 3.8.17
+
+ Can be set to ``None`` for :meth:`~TarFile.extract` and
+ :meth:`~TarFile.extractall`, causing extraction to skip applying this
+ attribute.
.. attribute:: TarInfo.uname
+ :type: str
User name.
+ .. versionchanged:: 3.8.17
+
+ Can be set to ``None`` for :meth:`~TarFile.extract` and
+ :meth:`~TarFile.extractall`, causing extraction to skip applying this
+ attribute.
.. attribute:: TarInfo.gname
+ :type: str
Group name.
+ .. versionchanged:: 3.8.17
+
+ Can be set to ``None`` for :meth:`~TarFile.extract` and
+ :meth:`~TarFile.extractall`, causing extraction to skip applying this
+ attribute.
.. attribute:: TarInfo.pax_headers
+ :type: dict
A dictionary containing key-value pairs of an associated pax extended header.
+.. method:: TarInfo.replace(name=..., mtime=..., mode=..., linkname=...,
+ uid=..., gid=..., uname=..., gname=...,
+ deep=True)
+
+ .. versionadded:: 3.8.17
+
+ Return a *new* copy of the :class:`!TarInfo` object with the given attributes
+ changed. For example, to return a ``TarInfo`` with the group name set to
+ ``'staff'``, use::
+
+ new_tarinfo = old_tarinfo.replace(gname='staff')
+
+ By default, a deep copy is made.
+ If *deep* is false, the copy is shallow, i.e. ``pax_headers``
+ and any custom attributes are shared with the original ``TarInfo`` object.
A :class:`TarInfo` object also provides some convenient query methods:
@@ -666,9 +839,259 @@ A :class:`TarInfo` object also provides some convenient query methods:
Return :const:`True` if it is one of character device, block device or FIFO.
+.. _tarfile-extraction-filter:
+
+Extraction filters
+------------------
+
+.. versionadded:: 3.8.17
+
+The *tar* format is designed to capture all details of a UNIX-like filesystem,
+which makes it very powerful.
+Unfortunately, the features make it easy to create tar files that have
+unintended -- and possibly malicious -- effects when extracted.
+For example, extracting a tar file can overwrite arbitrary files in various
+ways (e.g. by using absolute paths, ``..`` path components, or symlinks that
+affect later members).
+
+In most cases, the full functionality is not needed.
+Therefore, *tarfile* supports extraction filters: a mechanism to limit
+functionality, and thus mitigate some of the security issues.
+
+.. seealso::
+
+ :pep:`706`
+ Contains further motivation and rationale behind the design.
+
+The *filter* argument to :meth:`TarFile.extract` or :meth:`~TarFile.extractall`
+can be:
+
+* the string ``'fully_trusted'``: Honor all metadata as specified in the
+ archive.
+ Should be used if the user trusts the archive completely, or implements
+ their own complex verification.
+
+* the string ``'tar'``: Honor most *tar*-specific features (i.e. features of
+ UNIX-like filesystems), but block features that are very likely to be
+ surprising or malicious. See :func:`tar_filter` for details.
+
+* the string ``'data'``: Ignore or block most features specific to UNIX-like
+ filesystems. Intended for extracting cross-platform data archives.
+ See :func:`data_filter` for details.
+
+* ``None`` (default): Use :attr:`TarFile.extraction_filter`.
+
+ If that is also ``None`` (the default), the ``'fully_trusted'``
+ filter will be used (for compatibility with earlier versions of Python).
+
+ In Python 3.12, the default will emit a ``DeprecationWarning``.
+
+ In Python 3.14, the ``'data'`` filter will become the default instead.
+ It's possible to switch earlier; see :attr:`TarFile.extraction_filter`.
+
+* A callable which will be called for each extracted member with a
+ :ref:`TarInfo <tarinfo-objects>` describing the member and the destination
+ path to where the archive is extracted (i.e. the same path is used for all
+ members)::
+
+ filter(/, member: TarInfo, path: str) -> TarInfo | None
+
+ The callable is called just before each member is extracted, so it can
+ take the current state of the disk into account.
+ It can:
+
+ - return a :class:`TarInfo` object which will be used instead of the metadata
+ in the archive, or
+ - return ``None``, in which case the member will be skipped, or
+ - raise an exception to abort the operation or skip the member,
+ depending on :attr:`~TarFile.errorlevel`.
+ Note that when extraction is aborted, :meth:`~TarFile.extractall` may leave
+ the archive partially extracted. It does not attempt to clean up.
+
+Default named filters
+~~~~~~~~~~~~~~~~~~~~~
+
+The pre-defined, named filters are available as functions, so they can be
+reused in custom filters:
+
+.. function:: fully_trusted_filter(/, member, path)
+
+ Return *member* unchanged.
+
+ This implements the ``'fully_trusted'`` filter.
+
+.. function:: tar_filter(/, member, path)
+
+ Implements the ``'tar'`` filter.
+
+ - Strip leading slashes (``/`` and :attr:`os.sep`) from filenames.
+ - :ref:`Refuse <tarfile-extraction-refuse>` to extract files with absolute
+ paths (in case the name is absolute
+ even after stripping slashes, e.g. ``C:/foo`` on Windows).
+ This raises :class:`~tarfile.AbsolutePathError`.
+ - :ref:`Refuse <tarfile-extraction-refuse>` to extract files whose absolute
+ path (after following symlinks) would end up outside the destination.
+ This raises :class:`~tarfile.OutsideDestinationError`.
+ - Clear high mode bits (setuid, setgid, sticky) and group/other write bits
+ (:attr:`~stat.S_IWGRP`|:attr:`~stat.S_IWOTH`).
+
+ Return the modified ``TarInfo`` member.
+
+.. function:: data_filter(/, member, path)
+
+ Implements the ``'data'`` filter.
+ In addition to what ``tar_filter`` does:
+
+ - :ref:`Refuse <tarfile-extraction-refuse>` to extract links (hard or soft)
+ that link to absolute paths, or ones that link outside the destination.
+
+ This raises :class:`~tarfile.AbsoluteLinkError` or
+ :class:`~tarfile.LinkOutsideDestinationError`.
+
+ Note that such files are refused even on platforms that do not support
+ symbolic links.
+
+ - :ref:`Refuse <tarfile-extraction-refuse>` to extract device files
+ (including pipes).
+ This raises :class:`~tarfile.SpecialFileError`.
+
+ - For regular files, including hard links:
+
+ - Set the owner read and write permissions
+ (:attr:`~stat.S_IRUSR`|:attr:`~stat.S_IWUSR`).
+ - Remove the group & other executable permission
+ (:attr:`~stat.S_IXGRP`|:attr:`~stat.S_IXOTH`)
+ if the owner doesn’t have it (:attr:`~stat.S_IXUSR`).
+
+ - For other files (directories), set ``mode`` to ``None``, so
+ that extraction methods skip applying permission bits.
+ - Set user and group info (``uid``, ``gid``, ``uname``, ``gname``)
+ to ``None``, so that extraction methods skip setting it.
+
+ Return the modified ``TarInfo`` member.
+
+
+.. _tarfile-extraction-refuse:
+
+Filter errors
+~~~~~~~~~~~~~
+
+When a filter refuses to extract a file, it will raise an appropriate exception,
+a subclass of :class:`~tarfile.FilterError`.
+This will abort the extraction if :attr:`TarFile.errorlevel` is 1 or more.
+With ``errorlevel=0`` the error will be logged and the member will be skipped,
+but extraction will continue.
+
+
+Hints for further verification
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Even with ``filter='data'``, *tarfile* is not suited for extracting untrusted
+files without prior inspection.
+Among other issues, the pre-defined filters do not prevent denial-of-service
+attacks. Users should do additional checks.
+
+Here is an incomplete list of things to consider:
+
+* Extract to a :func:`new temporary directory <tempfile.mkdtemp>`
+ to prevent e.g. exploiting pre-existing links, and to make it easier to
+ clean up after a failed extraction.
+* When working with untrusted data, use external (e.g. OS-level) limits on
+ disk, memory and CPU usage.
+* Check filenames against an allow-list of characters
+ (to filter out control characters, confusables, foreign path separators,
+ etc.).
+* Check that filenames have expected extensions (discouraging files that
+ execute when you “click on them”, or extension-less files like Windows special device names).
+* Limit the number of extracted files, total size of extracted data,
+ filename length (including symlink length), and size of individual files.
+* Check for files that would be shadowed on case-insensitive filesystems.
+
+Also note that:
+
+* Tar files may contain multiple versions of the same file.
+ Later ones are expected to overwrite any earlier ones.
+ This feature is crucial to allow updating tape archives, but can be abused
+ maliciously.
+* *tarfile* does not protect against issues with “live” data,
+ e.g. an attacker tinkering with the destination (or source) directory while
+ extraction (or archiving) is in progress.
+
+
+Supporting older Python versions
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Extraction filters were added to Python 3.12, and are backported to older
+versions as security updates.
+To check whether the feature is available, use e.g.
+``hasattr(tarfile, 'data_filter')`` rather than checking the Python version.
+
+The following examples show how to support Python versions with and without
+the feature.
+Note that setting ``extraction_filter`` will affect any subsequent operations.
+
+* Fully trusted archive::
+
+ my_tarfile.extraction_filter = (lambda member, path: member)
+ my_tarfile.extractall()
+
+* Use the ``'data'`` filter if available, but revert to Python 3.11 behavior
+ (``'fully_trusted'``) if this feature is not available::
+
+ my_tarfile.extraction_filter = getattr(tarfile, 'data_filter',
+ (lambda member, path: member))
+ my_tarfile.extractall()
+
+* Use the ``'data'`` filter; *fail* if it is not available::
+
+ my_tarfile.extractall(filter=tarfile.data_filter)
+
+ or::
+
+ my_tarfile.extraction_filter = tarfile.data_filter
+ my_tarfile.extractall()
+
+* Use the ``'data'`` filter; *warn* if it is not available::
+
+ if hasattr(tarfile, 'data_filter'):
+ my_tarfile.extractall(filter='data')
+ else:
+ # remove this when no longer needed
+ warn_the_user('Extracting may be unsafe; consider updating Python')
+ my_tarfile.extractall()
+
+
+Stateful extraction filter example
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+While *tarfile*'s extraction methods take a simple *filter* callable,
+custom filters may be more complex objects with an internal state.
+It may be useful to write these as context managers, to be used like this::
+
+ with StatefulFilter() as filter_func:
+ tar.extractall(path, filter=filter_func)
+
+Such a filter can be written as, for example::
+
+ class StatefulFilter:
+ def __init__(self):
+ self.file_count = 0
+
+ def __enter__(self):
+ return self
+
+ def __call__(self, member, path):
+ self.file_count += 1
+ return member
+
+ def __exit__(self, *exc_info):
+ print(f'{self.file_count} files extracted')
+
+
.. _tarfile-commandline:
.. program:: tarfile
+
Command-Line Interface
----------------------
@@ -738,6 +1161,15 @@ Command-line options
Verbose output.
+.. cmdoption:: --filter <filtername>
+
+ Specifies the *filter* for ``--extract``.
+ See :ref:`tarfile-extraction-filter` for details.
+ Only string names are accepted (that is, ``fully_trusted``, ``tar``,
+ and ``data``).
+
+ .. versionadded:: 3.8.17
+
.. _tar-examples:
Examples
diff --git a/Doc/whatsnew/3.8.rst b/Doc/whatsnew/3.8.rst
index 630e060cb07a..e5278da3f6a5 100644
--- a/Doc/whatsnew/3.8.rst
+++ b/Doc/whatsnew/3.8.rst
@@ -2339,3 +2339,19 @@ This limit can be configured or disabled by environment variable, command
line flag, or :mod:`sys` APIs. See the :ref:`integer string conversion
length limitation <int_max_str_digits>` documentation. The default limit
is 4300 digits in string form.
+
+Notable Changes in 3.8.17
+=========================
+
+tarfile
+-------
+
+* The extraction methods in :mod:`tarfile`, and :func:`shutil.unpack_archive`,
+ have a new a *filter* argument that allows limiting tar features than may be
+ surprising or dangerous, such as creating files outside the destination
+ directory.
+ See :ref:`tarfile-extraction-filter` for details.
+ In Python 3.12, use without the *filter* argument will show a
+ :exc:`DeprecationWarning`.
+ In Python 3.14, the default will switch to ``'data'``.
+ (Contributed by Petr Viktorin in :pep:`706`.)
diff --git a/Lib/shutil.py b/Lib/shutil.py
index fdadb838000c..acb0eb18714f 100644
--- a/Lib/shutil.py
+++ b/Lib/shutil.py
@@ -1161,7 +1161,7 @@ def _unpack_zipfile(filename, extract_dir):
finally:
zip.close()
-def _unpack_tarfile(filename, extract_dir):
+def _unpack_tarfile(filename, extract_dir, *, filter=None):
"""Unpack tar/tar.gz/tar.bz2/tar.xz `filename` to `extract_dir`
"""
import tarfile # late import for breaking circular dependency
@@ -1171,7 +1171,7 @@ def _unpack_tarfile(filename, extract_dir):
raise ReadError(
"%s is not a compressed or uncompressed tar file" % filename)
try:
- tarobj.extractall(extract_dir)
+ tarobj.extractall(extract_dir, filter=filter)
finally:
tarobj.close()
@@ -1199,7 +1199,7 @@ def _find_unpack_format(filename):
return name
return None
-def unpack_archive(filename, extract_dir=None, format=None):
+def unpack_archive(filename, extract_dir=None, format=None, *, filter=None):
"""Unpack an archive.
`filename` is the name of the archive.
@@ -1213,6 +1213,9 @@ def unpack_archive(filename, extract_dir=None, format=None):
was registered for that extension.
In case none is found, a ValueError is raised.
+
+ If `filter` is given, it is passed to the underlying
+ extraction function.
"""
sys.audit("shutil.unpack_archive", filename, extract_dir, format)
@@ -1222,6 +1225,10 @@ def unpack_archive(filename, extract_dir=None, format=None):
extract_dir = os.fspath(extract_dir)
filename = os.fspath(filename)
+ if filter is None:
+ filter_kwargs = {}
+ else:
+ filter_kwargs = {'filter': filter}
if format is not None:
try:
format_info = _UNPACK_FORMATS[format]
@@ -1229,7 +1236,7 @@ def unpack_archive(filename, extract_dir=None, format=None):
raise ValueError("Unknown unpack format '{0}'".format(format)) from None
func = format_info[1]
- func(filename, extract_dir, **dict(format_info[2]))
+ func(filename, extract_dir, **dict(format_info[2]), **filter_kwargs)
else:
# we need to look at the registered unpackers supported extensions
format = _find_unpack_format(filename)
@@ -1238,6 +1245,7 @@ def unpack_archive(filename, extract_dir=None, format=None):
func = _UNPACK_FORMATS[format][1]
kwargs = dict(_UNPACK_FORMATS[format][2])
+ kwargs.update(filter_kwargs)
func(filename, extract_dir, **kwargs)
diff --git a/Lib/tarfile.py b/Lib/tarfile.py
index 30150ec6cca6..5291622ab8e9 100755
--- a/Lib/tarfile.py
+++ b/Lib/tarfile.py
@@ -46,6 +46,7 @@
import struct
import copy
import re
+import warnings
try:
import pwd
@@ -71,6 +72,7 @@
"ENCODING", "USTAR_FORMAT", "GNU_FORMAT", "PAX_FORMAT",
"DEFAULT_FORMAT", "open"]
+
#---------------------------------------------------------
# tar constants
#---------------------------------------------------------
@@ -158,6 +160,8 @@
def stn(s, length, encoding, errors):
"""Convert a string to a null-terminated bytes object.
"""
+ if s is None:
+ raise ValueError("metadata cannot contain None")
s = s.encode(encoding, errors)
return s[:length] + (length - len(s)) * NUL
@@ -708,9 +712,127 @@ def __init__(self, tarfile, tarinfo):
super().__init__(fileobj)
#class ExFileObject
+
+#-----------------------------
+# extraction filters (PEP 706)
+#-----------------------------
+
+class FilterError(TarError):
+ pass
+
+class AbsolutePathError(FilterError):
+ def __init__(self, tarinfo):
+ self.tarinfo = tarinfo
+ super().__init__(f'member {tarinfo.name!r} has an absolute path')
+
+class OutsideDestinationError(FilterError):
+ def __init__(self, tarinfo, path):
+ self.tarinfo = tarinfo
+ self._path = path
+ super().__init__(f'{tarinfo.name!r} would be extracted to {path!r}, '
+ + 'which is outside the destination')
+
+class SpecialFileError(FilterError):
+ def __init__(self, tarinfo):
+ self.tarinfo = tarinfo
+ super().__init__(f'{tarinfo.name!r} is a special file')
+
+class AbsoluteLinkError(FilterError):
+ def __init__(self, tarinfo):
+ self.tarinfo = tarinfo
+ super().__init__(f'{tarinfo.name!r} is a symlink to an absolute path')
+
+class LinkOutsideDestinationError(FilterError):
+ def __init__(self, tarinfo, path):
+ self.tarinfo = tarinfo
+ self._path = path
+ super().__init__(f'{tarinfo.name!r} would link to {path!r}, '
+ + 'which is outside the destination')
+
+def _get_filtered_attrs(member, dest_path, for_data=True):
+ new_attrs = {}
+ name = member.name
+ dest_path = os.path.realpath(dest_path)
+ # Strip leading / (tar's directory separator) from filenames.
+ # Include os.sep (target OS directory separator) as well.
+ if name.startswith(('/', os.sep)):
+ name = new_attrs['name'] = member.path.lstrip('/' + os.sep)
+ if os.path.isabs(name):
+ # Path is absolute even after stripping.
+ # For example, 'C:/foo' on Windows.
+ raise AbsolutePathError(member)
+ # Ensure we stay in the destination
+ target_path = os.path.realpath(os.path.join(dest_path, name))
+ if os.path.commonpath([target_path, dest_path]) != dest_path:
+ raise OutsideDestinationError(member, target_path)
+ # Limit permissions (no high bits, and go-w)
+ mode = member.mode
+ if mode is not None:
+ # Strip high bits & group/other write bits
+ mode = mode & 0o755
+ if for_data:
+ # For data, handle permissions & file types
+ if member.isreg() or member.islnk():
+ if not mode & 0o100:
+ # Clear executable bits if not executable by user
+ mode &= ~0o111
+ # Ensure owner can read & write
+ mode |= 0o600
+ elif member.isdir() or member.issym():
+ # Ignore mode for directories & symlinks
+ mode = None
+ else:
+ # Reject special files
+ raise SpecialFileError(member)
+ if mode != member.mode:
+ new_attrs['mode'] = mode
+ if for_data:
+ # Ignore ownership for 'data'
+ if member.uid is not None:
+ new_attrs['uid'] = None
+ if member.gid is not None:
+ new_attrs['gid'] = None
+ if member.uname is not None:
+ new_attrs['uname'] = None
+ if member.gname is not None:
+ new_attrs['gname'] = None
+ # Check link destination for 'data'
+ if member.islnk() or member.issym():
+ if os.path.isabs(member.linkname):
+ raise AbsoluteLinkError(member)
+ target_path = os.path.realpath(os.path.join(dest_path, member.linkname))
+ if os.path.commonpath([target_path, dest_path]) != dest_path:
+ raise LinkOutsideDestinationError(member, target_path)
+ return new_attrs
+
+def fully_trusted_filter(member, dest_path):
+ return member
+
+def tar_filter(member, dest_path):
+ new_attrs = _get_filtered_attrs(member, dest_path, False)
+ if new_attrs:
+ return member.replace(**new_attrs, deep=False)
+ return member
+
+def data_filter(member, dest_path):
+ new_attrs = _get_filtered_attrs(member, dest_path, True)
+ if new_attrs:
+ return member.replace(**new_attrs, deep=False)
+ return member
+
+_NAMED_FILTERS = {
+ "fully_trusted": fully_trusted_filter,
+ "tar": tar_filter,
+ "data": data_filter,
+}
+
#------------------
# Exported Classes
#------------------
+
+# Sentinel for replace() defaults, meaning "don't change the attribute"
+_KEEP = object()
+
class TarInfo(object):
"""Informational class which holds the details about an
archive member given by a tar header block.
@@ -791,12 +913,44 @@ def linkpath(self, linkname):
def __repr__(self):
return "<%s %r at %#x>" % (self.__class__.__name__,self.name,id(self))
+ def replace(self, *,
+ name=_KEEP, mtime=_KEEP, mode=_KEEP, linkname=_KEEP,
+ uid=_KEEP, gid=_KEEP, uname=_KEEP, gname=_KEEP,
+ deep=True, _KEEP=_KEEP):
+ """Return a deep copy of self with the given attributes replaced.
+ """
+ if deep:
+ result = copy.deepcopy(self)
+ else:
+ result = copy.copy(self)
+ if name is not _KEEP:
+ result.name = name
+ if mtime is not _KEEP:
+ result.mtime = mtime
+ if mode is not _KEEP:
+ result.mode = mode
+ if linkname is not _KEEP:
+ result.linkname = linkname
+ if uid is not _KEEP:
+ result.uid = uid
+ if gid is not _KEEP:
+ result.gid = gid
+ if uname is not _KEEP:
+ result.uname = uname
+ if gname is not _KEEP:
+ result.gname = gname
+ return result
+
def get_info(self):
"""Return the TarInfo's attributes as a dictionary.
"""
+ if self.mode is None:
+ mode = None
+ else:
+ mode = self.mode & 0o7777
info = {
"name": self.name,
- "mode": self.mode & 0o7777,
+ "mode": mode,
"uid": self.uid,
"gid": self.gid,
"size": self.size,
@@ -819,6 +973,9 @@ def tobuf(self, format=DEFAULT_FORMAT, encoding=ENCODING, errors="surrogateescap
"""Return a tar header as a string of 512 byte blocks.
"""
info = self.get_info()
+ for name, value in info.items():
+ if value is None:
+ raise ValueError("%s may not be None" % name)
if format == USTAR_FORMAT:
return self.create_ustar_header(info, encoding, errors)
@@ -932,6 +1089,20 @@ def _create_header(info, format, encoding, errors):
"""Return a header block. info is a dictionary with file
information, format must be one of the *_FORMAT constants.
"""
+ has_device_fields = info.get("type") in (CHRTYPE, BLKTYPE)
+ if has_device_fields:
+ devmajor = itn(info.get("devmajor", 0), 8, format)
+ devminor = itn(info.get("devminor", 0), 8, format)
+ else:
+ devmajor = stn("", 8, encoding, errors)
+ devminor = stn("", 8, encoding, errors)
+
+ # None values in metadata should cause ValueError.
+ # itn()/stn() do this for all fields except type.
+ filetype = info.get("type", REGTYPE)
+ if filetype is None:
+ raise ValueError("TarInfo.type must not be None")
+
parts = [
stn(info.get("name", ""), 100, encoding, errors),
itn(info.get("mode", 0) & 0o7777, 8, format),
@@ -940,7 +1111,7 @@ def _create_header(info, format, encoding, errors):
itn(info.get("size", 0), 12, format),
itn(info.get("mtime", 0), 12, format),
b" ", # checksum field
- info.get("type", REGTYPE),
+ filetype,
stn(info.get("linkname", ""), 100, encoding, errors),
info.get("magic", POSIX_MAGIC),
stn(info.get("uname", ""), 32, encoding, errors),
@@ -1440,6 +1611,8 @@ class TarFile(object):
fileobject = ExFileObject # The file-object for extractfile().
+ extraction_filter = None # The default filter for extraction.
+
def __init__(self, name=None, mode="r", fileobj=None, format=None,
tarinfo=None, dereference=None, ignore_zeros=None, encoding=None,
errors="surrogateescape", pax_headers=None, debug=None,
@@ -1909,7 +2082,10 @@ def list(self, verbose=True, *, members=None):
members = self
for tarinfo in members:
if verbose:
- _safe_print(stat.filemode(tarinfo.mode))
+ if tarinfo.mode is None:
+ _safe_print("??????????")
+ else:
+ _safe_print(stat.filemode(tarinfo.mode))
_safe_print("%s/%s" % (tarinfo.uname or tarinfo.uid,
tarinfo.gname or tarinfo.gid))
if tarinfo.ischr() or tarinfo.isblk():
@@ -1917,8 +2093,11 @@ def list(self, verbose=True, *, members=None):
("%d,%d" % (tarinfo.devmajor, tarinfo.devminor)))
else:
_safe_print("%10d" % tarinfo.size)
- _safe_print("%d-%02d-%02d %02d:%02d:%02d" \
- % time.localtime(tarinfo.mtime)[:6])
+ if tarinfo.mtime is None:
+ _safe_print("????-??-?? ??:??:??")
+ else:
+ _safe_print("%d-%02d-%02d %02d:%02d:%02d" \
+ % time.localtime(tarinfo.mtime)[:6])
_safe_print(tarinfo.name + ("/" if tarinfo.isdir() else ""))
@@ -2005,32 +2184,58 @@ def addfile(self, tarinfo, fileobj=None):
self.members.append(tarinfo)
- def extractall(self, path=".", members=None, *, numeric_owner=False):
+ def _get_filter_function(self, filter):
+ if filter is None:
+ filter = self.extraction_filter
+ if filter is None:
+ return fully_trusted_filter
+ if isinstance(filter, str):
+ raise TypeError(
+ 'String names are not supported for '
+ + 'TarFile.extraction_filter. Use a function such as '
+ + 'tarfile.data_filter directly.')
+ return filter
+ if callable(filter):
+ return filter
+ try:
+ return _NAMED_FILTERS[filter]
+ except KeyError:
+ raise ValueError(f"filter {filter!r} not found") from None
+
+ def extractall(self, path=".", members=None, *, numeric_owner=False,
+ filter=None):
"""Extract all members from the archive to the current working
directory and set owner, modification time and permissions on
directories afterwards. `path' specifies a different directory
to extract to. `members' is optional and must be a subset of the
list returned by getmembers(). If `numeric_owner` is True, only
the numbers for user/group names are used and not the names.
+
+ The `filter` function will be called on each member just
+ before extraction.
+ It can return a changed TarInfo or None to skip the member.
+ String names of common filters are accepted.
"""
directories = []
+ filter_function = self._get_filter_function(filter)
if members is None:
members = self
- for tarinfo in members:
+ for member in members:
+ tarinfo = self._get_extract_tarinfo(member, filter_function, path)
+ if tarinfo is None:
+ continue
if tarinfo.isdir():
- # Extract directories with a safe mode.
+ # For directories, delay setting attributes until later,
+ # since permissions can interfere with extraction and
+ # extracting contents can reset mtime.
directories.append(tarinfo)
- tarinfo = copy.copy(tarinfo)
- tarinfo.mode = 0o700
- # Do not set_attrs directories, as we will do that further down
- self.extract(tarinfo, path, set_attrs=not tarinfo.isdir(),
- numeric_owner=numeric_owner)
+ self._extract_one(tarinfo, path, set_attrs=not tarinfo.isdir(),
+ numeric_owner=numeric_owner)
# Reverse sort directories.
- directories.sort(key=lambda a: a.name)
- directories.reverse()
+ directories.sort(key=lambda a: a.name, reverse=True)
# Set correct owner, mtime and filemode on directories.
for tarinfo in directories:
@@ -2040,12 +2245,10 @@ def extractall(self, path=".", members=None, *, numeric_owner=False):
self.utime(tarinfo, dirpath)
self.chmod(tarinfo, dirpath)
except ExtractError as e:
- if self.errorlevel > 1:
- raise
- else:
- self._dbg(1, "tarfile: %s" % e)
+ self._handle_nonfatal_error(e)
- def extract(self, member, path="", set_attrs=True, *, numeric_owner=False):
+ def extract(self, member, path="", set_attrs=True, *, numeric_owner=False,
+ filter=None):
"""Extract a member from the archive to the current working directory,
using its full name. Its file information is extracted as accurately
as possible. `member' may be a filename or a TarInfo object. You can
@@ -2053,35 +2256,70 @@ def extract(self, member, path="", set_attrs=True, *, numeric_owner=False):
mtime, mode) are set unless `set_attrs' is False. If `numeric_owner`
is True, only the numbers for user/group names are used and not
the names.
+
+ The `filter` function will be called before extraction.
+ It can return a changed TarInfo or None to skip the member.
+ String names of common filters are accepted.
"""
- self._check("r")
+ filter_function = self._get_filter_function(filter)
+ tarinfo = self._get_extract_tarinfo(member, filter_function, path)
+ if tarinfo is not None:
+ self._extract_one(tarinfo, path, set_attrs, numeric_owner)
+ def _get_extract_tarinfo(self, member, filter_function, path):
+ """Get filtered TarInfo (or None) from member, which might be a str"""
if isinstance(member, str):
tarinfo = self.getmember(member)
else:
tarinfo = member
+ unfiltered = tarinfo
+ try:
+ tarinfo = filter_function(tarinfo, path)
+ except (OSError, FilterError) as e:
+ self._handle_fatal_error(e)
+ except ExtractError as e:
+ self._handle_nonfatal_error(e)
+ if tarinfo is None:
+ self._dbg(2, "tarfile: Excluded %r" % unfiltered.name)
+ return None
# Prepare the link target for makelink().
if tarinfo.islnk():
+ tarinfo = copy.copy(tarinfo)
tarinfo._link_target = os.path.join(path, tarinfo.linkname)
+ return tarinfo
+
+ def _extract_one(self, tarinfo, path, set_attrs, numeric_owner):
+ """Extract from filtered tarinfo to disk"""
+ self._check("r")
try:
self._extract_member(tarinfo, os.path.join(path, tarinfo.name),
set_attrs=set_attrs,
numeric_owner=numeric_owner)
except OSError as e:
- if self.errorlevel > 0:
- raise
- else:
- if e.filename is None:
- self._dbg(1, "tarfile: %s" % e.strerror)
- else:
- self._dbg(1, "tarfile: %s %r" % (e.strerror, e.filename))
+ self._handle_fatal_error(e)
except ExtractError as e:
- if self.errorlevel > 1:
- raise
+ self._handle_nonfatal_error(e)
+
+ def _handle_nonfatal_error(self, e):
+ """Handle non-fatal error (ExtractError) according to errorlevel"""
+ if self.errorlevel > 1:
+ raise
+ else:
+ self._dbg(1, "tarfile: %s" % e)
+
+ def _handle_fatal_error(self, e):
+ """Handle "fatal" error according to self.errorlevel"""
+ if self.errorlevel > 0:
+ raise
+ elif isinstance(e, OSError):
+ if e.filename is None:
+ self._dbg(1, "tarfile: %s" % e.strerror)
else:
- self._dbg(1, "tarfile: %s" % e)
+ self._dbg(1, "tarfile: %s %r" % (e.strerror, e.filename))
+ else:
+ self._dbg(1, "tarfile: %s %s" % (type(e).__name__, e))
def extractfile(self, member):
"""Extract a member from the archive as a file object. `member' may be
@@ -2167,9 +2405,13 @@ def makedir(self, tarinfo, targetpath):
"""Make a directory called targetpath.
"""
try:
- # Use a safe mode for the directory, the real mode is set
- # later in _extract_member().
- os.mkdir(targetpath, 0o700)
+ if tarinfo.mode is None:
+ # Use the system's default mode
+ os.mkdir(targetpath)
+ else:
+ # Use a safe mode for the directory, the real mode is set
+ # later in _extract_member().
+ os.mkdir(targetpath, 0o700)
except FileExistsError:
pass
@@ -2212,6 +2454,9 @@ def makedev(self, tarinfo, targetpath):
raise ExtractError("special devices not supported by system")
mode = tarinfo.mode
+ if mode is None:
+ # Use mknod's default
+ mode = 0o600
if tarinfo.isblk():
mode |= stat.S_IFBLK
else:
@@ -2233,7 +2478,6 @@ def makelink(self, tarinfo, targetpath):
os.unlink(targetpath)
os.symlink(tarinfo.linkname, targetpath)
else:
- # See extract().
if os.path.exists(tarinfo._link_target):
os.link(tarinfo._link_target, targetpath)
else:
@@ -2258,15 +2502,19 @@ def chown(self, tarinfo, targetpath, numeric_owner):
u = tarinfo.uid
if not numeric_owner:
try:
- if grp:
+ if grp and tarinfo.gname:
g = grp.getgrnam(tarinfo.gname)[2]
except KeyError:
pass
try:
- if pwd:
+ if pwd and tarinfo.uname:
u = pwd.getpwnam(tarinfo.uname)[2]
except KeyError:
pass
+ if g is None:
+ g = -1
+ if u is None:
+ u = -1
try:
if tarinfo.issym() and hasattr(os, "lchown"):
os.lchown(targetpath, u, g)
@@ -2278,6 +2526,8 @@ def chown(self, tarinfo, targetpath, numeric_owner):
def chmod(self, tarinfo, targetpath):
"""Set file permissions of targetpath according to tarinfo.
"""
+ if tarinfo.mode is None:
+ return
try:
os.chmod(targetpath, tarinfo.mode)
except OSError:
@@ -2286,10 +2536,13 @@ def chmod(self, tarinfo, targetpath):
def utime(self, tarinfo, targetpath):
"""Set modification time of targetpath according to tarinfo.
"""
+ mtime = tarinfo.mtime
+ if mtime is None:
+ return
if not hasattr(os, 'utime'):
return
try:
- os.utime(targetpath, (tarinfo.mtime, tarinfo.mtime))
+ os.utime(targetpath, (mtime, mtime))
except OSError:
raise ExtractError("could not change modification time")
@@ -2356,13 +2609,26 @@ def _getmember(self, name, tarinfo=None, normalize=False):
members = self.getmembers()
# Limit the member search list up to tarinfo.
+ skipping = False
if tarinfo is not None:
- members = members[:members.index(tarinfo)]
+ try:
+ index = members.index(tarinfo)
+ except ValueError:
+ # The given starting point might be a (modified) copy.
+ # We'll later skip members until we find an equivalent.
+ skipping = True
+ else:
+ # Happy fast path
+ members = members[:index]
if normalize:
name = os.path.normpath(name)
for member in reversed(members):
+ if skipping:
+ if tarinfo.offset == member.offset:
+ skipping = False
+ continue
if normalize:
member_name = os.path.normpath(member.name)
else:
@@ -2371,6 +2637,10 @@ def _getmember(self, name, tarinfo=None, normalize=False):
if name == member_name:
return member
+ if skipping:
+ # Starting point was not found
+ raise ValueError(tarinfo)
+
def _load(self):
"""Read through the entire archive file and look for readable
members.
@@ -2463,6 +2733,7 @@ def __exit__(self, type, value, traceback):
#--------------------
# exported functions
#--------------------
+
def is_tarfile(name):
"""Return True if name points to a tar archive that we
are able to handle, else return False.
@@ -2484,6 +2755,10 @@ def main():
parser = argparse.ArgumentParser(description=description)
parser.add_argument('-v', '--verbose', action='store_true', default=False,
help='Verbose output')
+ parser.add_argument('--filter', metavar='<filtername>',
+ choices=_NAMED_FILTERS,
+ help='Filter for extraction')
+
group = parser.add_mutually_exclusive_group(required=True)
group.add_argument('-l', '--list', metavar='<tarfile>',
help='Show listing of a tarfile')
@@ -2495,8 +2770,12 @@ def main():
help='Create tarfile from sources')
group.add_argument('-t', '--test', metavar='<tarfile>',
help='Test if a tarfile is valid')
+
args = parser.parse_args()
+ if args.filter and args.extract is None:
+ parser.exit(1, '--filter is only valid for extraction\n')
+
if args.test is not None:
src = args.test
if is_tarfile(src):
@@ -2527,7 +2806,7 @@ def main():
if is_tarfile(src):
with TarFile.open(src, 'r:*') as tf:
- tf.extractall(path=curdir)
+ tf.extractall(path=curdir, filter=args.filter)
if args.verbose:
if curdir == '.':
msg = '{!r} file is extracted.'.format(src)
diff --git a/Lib/test/test_shutil.py b/Lib/test/test_shutil.py
index 37940c8dcf71..5cef59ea9c67 100644
--- a/Lib/test/test_shutil.py
+++ b/Lib/test/test_shutil.py
@@ -1458,12 +1458,16 @@ def test_register_archive_format(self):
formats = [name for name, params in get_archive_formats()]
self.assertNotIn('xxx', formats)
- def check_unpack_archive(self, format):
- self.check_unpack_archive_with_converter(format, lambda path: path)
- self.check_unpack_archive_with_converter(format, pathlib.Path)
- self.check_unpack_archive_with_converter(format, FakePath)
+ ### shutil.unpack_archive
- def check_unpack_archive_with_converter(self, format, converter):
+ def check_unpack_archive(self, format, **kwargs):
+ self.check_unpack_archive_with_converter(
+ format, lambda path: path, **kwargs)
+ self.check_unpack_archive_with_converter(
+ format, pathlib.Path, **kwargs)
+ self.check_unpack_archive_with_converter(format, FakePath, **kwargs)
+
+ def check_unpack_archive_with_converter(self, format, converter, **kwargs):
root_dir, base_dir = self._create_files()
expected = rlistdir(root_dir)
expected.remove('outer')
@@ -1473,36 +1477,47 @@ def check_unpack_archive_with_converter(self, format, converter):
# let's try to unpack it now
tmpdir2 = self.mkdtemp()
- unpack_archive(converter(filename), converter(tmpdir2))
+ unpack_archive(converter(filename), converter(tmpdir2), **kwargs)
self.assertEqual(rlistdir(tmpdir2), expected)
# and again, this time with the format specified
tmpdir3 = self.mkdtemp()
- unpack_archive(converter(filename), converter(tmpdir3), format=format)
+ unpack_archive(converter(filename), converter(tmpdir3), format=format,
+ **kwargs)
self.assertEqual(rlistdir(tmpdir3), expected)
- self.assertRaises(shutil.ReadError, unpack_archive, converter(TESTFN))
- self.assertRaises(ValueError, unpack_archive, converter(TESTFN), format='xxx')
+ with self.assertRaises(shutil.ReadError):
+ unpack_archive(converter(TESTFN), **kwargs)
+ with self.assertRaises(ValueError):
+ unpack_archive(converter(TESTFN), format='xxx', **kwargs)
+
+ def check_unpack_tarball(self, format):
+ self.check_unpack_archive(format, filter='fully_trusted')
+ self.check_unpack_archive(format, filter='data')
+ with support.check_no_warnings(self):
+ self.check_unpack_archive(format)
def test_unpack_archive_tar(self):
- self.check_unpack_archive('tar')
+ self.check_unpack_tarball('tar')
@support.requires_zlib
def test_unpack_archive_gztar(self):
- self.check_unpack_archive('gztar')
+ self.check_unpack_tarball('gztar')
@support.requires_bz2
def test_unpack_archive_bztar(self):
- self.check_unpack_archive('bztar')
+ self.check_unpack_tarball('bztar')
@support.requires_lzma
@unittest.skipIf(AIX and not _maxdataOK(), "AIX MAXDATA must be 0x20000000 or larger")
def test_unpack_archive_xztar(self):
- self.check_unpack_archive('xztar')
+ self.check_unpack_tarball('xztar')
@support.requires_zlib
def test_unpack_archive_zip(self):
self.check_unpack_archive('zip')
+ with self.assertRaises(TypeError):
+ self.check_unpack_archive('zip', filter='data')
def test_unpack_registry(self):
diff --git a/Lib/test/test_tarfile.py b/Lib/test/test_tarfile.py
index bee00c56d610..03be10b1fee2 100644
--- a/Lib/test/test_tarfile.py
+++ b/Lib/test/test_tarfile.py
@@ -5,13 +5,17 @@
from contextlib import contextmanager
from random import Random
import pathlib
+import shutil
+import re
+import warnings
+import stat
import unittest
import unittest.mock
import tarfile
from test import support
-from test.support import script_helper, requires_hashdigest
+from test.support import script_helper
# Check for our compression modules.
try:
@@ -2204,7 +2208,12 @@ def test__all__(self):
'EmptyHeaderError', 'TruncatedHeaderError',
'EOFHeaderError', 'InvalidHeaderError',
'SubsequentHeaderError', 'ExFileObject',
- 'main'}
+ 'main',
+ 'fully_trusted_filter', 'data_filter',
+ 'tar_filter', 'FilterError', 'AbsoluteLinkError',
+ 'OutsideDestinationError', 'SpecialFileError',
+ 'AbsolutePathError', 'LinkOutsideDestinationError',
+ }
support.check__all__(self, tarfile, blacklist=blacklist)
@@ -2227,6 +2236,15 @@ def make_simple_tarfile(self, tar_name):
for tardata in files:
tf.add(tardata, arcname=os.path.basename(tardata))
+ def make_evil_tarfile(self, tar_name):
+ files = [support.findfile('tokenize_tests.txt')]
+ self.addCleanup(support.unlink, tar_name)
+ with tarfile.open(tar_name, 'w') as tf:
+ benign = tarfile.TarInfo('benign')
+ tf.addfile(benign, fileobj=io.BytesIO(b''))
+ evil = tarfile.TarInfo('../evil')
+ tf.addfile(evil, fileobj=io.BytesIO(b''))
+
def test_bad_use(self):
rc, out, err = self.tarfilecmd_failure()
self.assertEqual(out, b'')
@@ -2380,6 +2398,25 @@ def test_extract_command_verbose(self):
finally:
support.rmtree(tarextdir)
+ def test_extract_command_filter(self):
+ self.make_evil_tarfile(tmpname)
+ # Make an inner directory, so the member named '../evil'
+ # is still extracted into `tarextdir`
+ destdir = os.path.join(tarextdir, 'dest')
+ os.mkdir(tarextdir)
+ try:
+ with support.temp_cwd(destdir):
+ self.tarfilecmd_failure('-e', tmpname,
+ '-v',
+ '--filter', 'data')
+ out = self.tarfilecmd('-e', tmpname,
+ '-v',
+ '--filter', 'fully_trusted',
+ PYTHONIOENCODING='utf-8')
+ self.assertIn(b' file is extracted.', out)
+ finally:
+ support.rmtree(tarextdir)
+
def test_extract_command_different_directory(self):
self.make_simple_tarfile(tmpname)
try:
@@ -2653,6 +2690,893 @@ def test_keyword_only(self, mock_geteuid):
tarfl.extract, filename_1, TEMPDIR, False, True)
+class ReplaceTests(ReadTest, unittest.TestCase):
+ def test_replace_name(self):
+ member = self.tar.getmember('ustar/regtype')
+ replaced = member.replace(name='misc/other')
+ self.assertEqual(replaced.name, 'misc/other')
+ self.assertEqual(member.name, 'ustar/regtype')
+ self.assertEqual(self.tar.getmember('ustar/regtype').name,
+ 'ustar/regtype')
+
+ def test_replace_deep(self):
+ member = self.tar.getmember('pax/regtype1')
+ replaced = member.replace()
+ replaced.pax_headers['gname'] = 'not-bar'
+ self.assertEqual(member.pax_headers['gname'], 'bar')
+ self.assertEqual(
+ self.tar.getmember('pax/regtype1').pax_headers['gname'], 'bar')
+
+ def test_replace_shallow(self):
+ member = self.tar.getmember('pax/regtype1')
+ replaced = member.replace(deep=False)
+ replaced.pax_headers['gname'] = 'not-bar'
+ self.assertEqual(member.pax_headers['gname'], 'not-bar')
+ self.assertEqual(
+ self.tar.getmember('pax/regtype1').pax_headers['gname'], 'not-bar')
+
+ def test_replace_all(self):
+ member = self.tar.getmember('ustar/regtype')
+ for attr_name in ('name', 'mtime', 'mode', 'linkname',
+ 'uid', 'gid', 'uname', 'gname'):
+ with self.subTest(attr_name=attr_name):
+ replaced = member.replace(**{attr_name: None})
+ self.assertEqual(getattr(replaced, attr_name), None)
+ self.assertNotEqual(getattr(member, attr_name), None)
+
+ def test_replace_internal(self):
+ member = self.tar.getmember('ustar/regtype')
+ with self.assertRaises(TypeError):
+ member.replace(offset=123456789)
+
+
+class NoneInfoExtractTests(ReadTest):
+ # These mainly check that all kinds of members are extracted successfully
+ # if some metadata is None.
+ # Some of the methods do additional spot checks.
+
+ # We also test that the default filters can deal with None.
+
+ extraction_filter = None
+
+ @classmethod
+ def setUpClass(cls):
+ tar = tarfile.open(tarname, mode='r', encoding="iso8859-1")
+ cls.control_dir = pathlib.Path(TEMPDIR) / "extractall_ctrl"
+ tar.errorlevel = 0
+ tar.extractall(cls.control_dir, filter=cls.extraction_filter)
+ tar.close()
+ cls.control_paths = set(
+ p.relative_to(cls.control_dir)
+ for p in pathlib.Path(cls.control_dir).glob('**/*'))
+
+ @classmethod
+ def tearDownClass(cls):
+ shutil.rmtree(cls.control_dir)
+
+ def check_files_present(self, directory):
+ got_paths = set(
+ p.relative_to(directory)
+ for p in pathlib.Path(directory).glob('**/*'))
+ self.assertEqual(self.control_paths, got_paths)
+
+ @contextmanager
+ def extract_with_none(self, *attr_names):
+ DIR = pathlib.Path(TEMPDIR) / "extractall_none"
+ self.tar.errorlevel = 0
+ for member in self.tar.getmembers():
+ for attr_name in attr_names:
+ setattr(member, attr_name, None)
+ with support.temp_dir(DIR):
+ self.tar.extractall(DIR, filter='fully_trusted')
+ self.check_files_present(DIR)
+ yield DIR
+
+ def test_extractall_none_mtime(self):
+ # mtimes of extracted files should be later than 'now' -- the mtime
+ # of a previously created directory.
+ now = pathlib.Path(TEMPDIR).stat().st_mtime
+ with self.extract_with_none('mtime') as DIR:
+ for path in pathlib.Path(DIR).glob('**/*'):
+ with self.subTest(path=path):
+ try:
+ mtime = path.stat().st_mtime
+ except OSError:
+ # Some systems can't stat symlinks, ignore those
+ if not path.is_symlink():
+ raise
+ else:
+ self.assertGreaterEqual(path.stat().st_mtime, now)
+
+ def test_extractall_none_mode(self):
+ # modes of directories and regular files should match the mode
+ # of a "normally" created directory or regular file
+ dir_mode = pathlib.Path(TEMPDIR).stat().st_mode
+ regular_file = pathlib.Path(TEMPDIR) / 'regular_file'
+ regular_file.write_text('')
+ regular_file_mode = regular_file.stat().st_mode
+ with self.extract_with_none('mode') as DIR:
+ for path in pathlib.Path(DIR).glob('**/*'):
+ with self.subTest(path=path):
+ if path.is_dir():
+ self.assertEqual(path.stat().st_mode, dir_mode)
+ elif path.is_file():
+ self.assertEqual(path.stat().st_mode,
+ regular_file_mode)
+
+ def test_extractall_none_uid(self):
+ with self.extract_with_none('uid'):
+ pass
+
+ def test_extractall_none_gid(self):
+ with self.extract_with_none('gid'):
+ pass
+
+ def test_extractall_none_uname(self):
+ with self.extract_with_none('uname'):
+ pass
+
+ def test_extractall_none_gname(self):
+ with self.extract_with_none('gname'):
+ pass
+
+ def test_extractall_none_ownership(self):
+ with self.extract_with_none('uid', 'gid', 'uname', 'gname'):
+ pass
+
+class NoneInfoExtractTests_Data(NoneInfoExtractTests, unittest.TestCase):
+ extraction_filter = 'data'
+
+class NoneInfoExtractTests_FullyTrusted(NoneInfoExtractTests,
+ unittest.TestCase):
+ extraction_filter = 'fully_trusted'
+
+class NoneInfoExtractTests_Tar(NoneInfoExtractTests, unittest.TestCase):
+ extraction_filter = 'tar'
+
+class NoneInfoExtractTests_Default(NoneInfoExtractTests,
+ unittest.TestCase):
+ extraction_filter = None
+
+class NoneInfoTests_Misc(unittest.TestCase):
+ def test_add(self):
+ # When addfile() encounters None metadata, it raises a ValueError
+ bio = io.BytesIO()
+ for tarformat in (tarfile.USTAR_FORMAT, tarfile.GNU_FORMAT,
+ tarfile.PAX_FORMAT):
+ with self.subTest(tarformat=tarformat):
+ tar = tarfile.open(fileobj=bio, mode='w', format=tarformat)
+ tarinfo = tar.gettarinfo(tarname)
+ try:
+ tar.addfile(tarinfo)
+ except Exception:
+ if tarformat == tarfile.USTAR_FORMAT:
+ # In the old, limited format, adding might fail for
+ # reasons like the UID being too large
+ pass
+ else:
+ raise
+ else:
+ for attr_name in ('mtime', 'mode', 'uid', 'gid',
+ 'uname', 'gname'):
+ with self.subTest(attr_name=attr_name):
+ replaced = tarinfo.replace(**{attr_name: None})
+ with self.assertRaisesRegex(ValueError,
+ f"{attr_name}"):
+ tar.addfile(replaced)
+
+ def test_list(self):
+ # Change some metadata to None, then compare list() output
+ # word-for-word. We want list() to not raise, and to only change
+ # printout for the affected piece of metadata.
+ # (n.b.: some contents of the test archive are hardcoded.)
+ for attr_names in ({'mtime'}, {'mode'}, {'uid'}, {'gid'},
+ {'uname'}, {'gname'},
+ {'uid', 'uname'}, {'gid', 'gname'}):
+ with self.subTest(attr_names=attr_names), \
+ tarfile.open(tarname, encoding="iso8859-1") as tar:
+ tio_prev = io.TextIOWrapper(io.BytesIO(), 'ascii', newline='\n')
+ with support.swap_attr(sys, 'stdout', tio_prev):
+ tar.list()
+ for member in tar.getmembers():
+ for attr_name in attr_names:
+ setattr(member, attr_name, None)
+ tio_new = io.TextIOWrapper(io.BytesIO(), 'ascii', newline='\n')
+ with support.swap_attr(sys, 'stdout', tio_new):
+ tar.list()
+ for expected, got in zip(tio_prev.detach().getvalue().split(),
+ tio_new.detach().getvalue().split()):
+ if attr_names == {'mtime'} and re.match(rb'2003-01-\d\d', expected):
+ self.assertEqual(got, b'????-??-??')
+ elif attr_names == {'mtime'} and re.match(rb'\d\d:\d\d:\d\d', expected):
+ self.assertEqual(got, b'??:??:??')
+ elif attr_names == {'mode'} and re.match(
+ rb'.([r-][w-][x-]){3}', expected):
+ self.assertEqual(got, b'??????????')
+ elif attr_names == {'uname'} and expected.startswith(
+ (b'tarfile/', b'lars/', b'foo/')):
+ exp_user, exp_group = expected.split(b'/')
+ got_user, got_group = got.split(b'/')
+ self.assertEqual(got_group, exp_group)
+ self.assertRegex(got_user, b'[0-9]+')
+ elif attr_names == {'gname'} and expected.endswith(
+ (b'/tarfile', b'/users', b'/bar')):
+ exp_user, exp_group = expected.split(b'/')
+ got_user, got_group = got.split(b'/')
+ self.assertEqual(got_user, exp_user)
+ self.assertRegex(got_group, b'[0-9]+')
+ elif attr_names == {'uid'} and expected.startswith(
+ (b'1000/')):
+ exp_user, exp_group = expected.split(b'/')
+ got_user, got_group = got.split(b'/')
+ self.assertEqual(got_group, exp_group)
+ self.assertEqual(got_user, b'None')
+ elif attr_names == {'gid'} and expected.endswith((b'/100')):
+ exp_user, exp_group = expected.split(b'/')
+ got_user, got_group = got.split(b'/')
+ self.assertEqual(got_user, exp_user)
+ self.assertEqual(got_group, b'None')
+ elif attr_names == {'uid', 'uname'} and expected.startswith(
+ (b'tarfile/', b'lars/', b'foo/', b'1000/')):
+ exp_user, exp_group = expected.split(b'/')
+ got_user, got_group = got.split(b'/')
+ self.assertEqual(got_group, exp_group)
+ self.assertEqual(got_user, b'None')
+ elif attr_names == {'gname', 'gid'} and expected.endswith(
+ (b'/tarfile', b'/users', b'/bar', b'/100')):
+ exp_user, exp_group = expected.split(b'/')
+ got_user, got_group = got.split(b'/')
+ self.assertEqual(got_user, exp_user)
+ self.assertEqual(got_group, b'None')
+ else:
+ # In other cases the output should be the same
+ self.assertEqual(expected, got)
+
+def _filemode_to_int(mode):
+ """Inverse of `stat.filemode` (for permission bits)
+
+ Using mode strings rather than numbers makes the later tests more readable.
+ """
+ str_mode = mode[1:]
+ result = (
+ {'r': stat.S_IRUSR, '-': 0}[str_mode[0]]
+ | {'w': stat.S_IWUSR, '-': 0}[str_mode[1]]
+ | {'x': stat.S_IXUSR, '-': 0,
+ 's': stat.S_IXUSR | stat.S_ISUID,
+ 'S': stat.S_ISUID}[str_mode[2]]
+ | {'r': stat.S_IRGRP, '-': 0}[str_mode[3]]
+ | {'w': stat.S_IWGRP, '-': 0}[str_mode[4]]
+ | {'x': stat.S_IXGRP, '-': 0,
+ 's': stat.S_IXGRP | stat.S_ISGID,
+ 'S': stat.S_ISGID}[str_mode[5]]
+ | {'r': stat.S_IROTH, '-': 0}[str_mode[6]]
+ | {'w': stat.S_IWOTH, '-': 0}[str_mode[7]]
+ | {'x': stat.S_IXOTH, '-': 0,
+ 't': stat.S_IXOTH | stat.S_ISVTX,
+ 'T': stat.S_ISVTX}[str_mode[8]]
+ )
+ # check we did this right
+ assert stat.filemode(result)[1:] == mode[1:]
+
+ return result
+
+class ArchiveMaker:
+ """Helper to create a tar file with specific contents
+
+ Usage:
+
+ with ArchiveMaker() as t:
+ t.add('filename', ...)
+
+ with t.open() as tar:
+ ... # `tar` is now a TarFile with 'filename' in it!
+ """
+ def __init__(self):
+ self.bio = io.BytesIO()
+
+ def __enter__(self):
+ self.tar_w = tarfile.TarFile(mode='w', fileobj=self.bio)
+ return self
+
+ def __exit__(self, *exc):
+ self.tar_w.close()
+ self.contents = self.bio.getvalue()
+ self.bio = None
+
+ def add(self, name, *, type=None, symlink_to=None, hardlink_to=None,
+ mode=None, **kwargs):
+ """Add a member to the test archive. Call within `with`."""
+ name = str(name)
+ tarinfo = tarfile.TarInfo(name).replace(**kwargs)
+ if mode:
+ tarinfo.mode = _filemode_to_int(mode)
+ if symlink_to is not None:
+ type = tarfile.SYMTYPE
+ tarinfo.linkname = str(symlink_to)
+ if hardlink_to is not None:
+ type = tarfile.LNKTYPE
+ tarinfo.linkname = str(hardlink_to)
+ if name.endswith('/') and type is None:
+ type = tarfile.DIRTYPE
+ if type is not None:
+ tarinfo.type = type
+ if tarinfo.isreg():
+ fileobj = io.BytesIO(bytes(tarinfo.size))
+ else:
+ fileobj = None
+ self.tar_w.addfile(tarinfo, fileobj)
+
+ def open(self, **kwargs):
+ """Open the resulting archive as TarFile. Call after `with`."""
+ bio = io.BytesIO(self.contents)
+ return tarfile.open(fileobj=bio, **kwargs)
+
+
+class TestExtractionFilters(unittest.TestCase):
+
+ # A temporary directory for the extraction results.
+ # All files that "escape" the destination path should still end
+ # up in this directory.
+ outerdir = pathlib.Path(TEMPDIR) / 'outerdir'
+
+ # The destination for the extraction, within `outerdir`
+ destdir = outerdir / 'dest'
+
+ @contextmanager
+ def check_context(self, tar, filter):
+ """Extracts `tar` to `self.destdir` and allows checking the result
+
+ If an error occurs, it must be checked using `expect_exception`
+
+ Otherwise, all resulting files must be checked using `expect_file`,
+ except the destination directory itself and parent directories of
+ other files.
+ When checking directories, do so before their contents.
+ """
+ with support.temp_dir(self.outerdir):
+ try:
+ tar.extractall(self.destdir, filter=filter)
+ except Exception as exc:
+ self.raised_exception = exc
+ self.expected_paths = set()
+ else:
+ self.raised_exception = None
+ self.expected_paths = set(self.outerdir.glob('**/*'))
+ self.expected_paths.discard(self.destdir)
+ try:
+ yield
+ finally:
+ tar.close()
+ if self.raised_exception:
+ raise self.raised_exception
+ self.assertEqual(self.expected_paths, set())
+
+ def expect_file(self, name, type=None, symlink_to=None, mode=None):
+ """Check a single file. See check_context."""
+ if self.raised_exception:
+ raise self.raised_exception
+ # use normpath() rather than resolve() so we don't follow symlinks
+ path = pathlib.Path(os.path.normpath(self.destdir / name))
+ self.assertIn(path, self.expected_paths)
+ self.expected_paths.remove(path)
+
+ # When checking mode, ignore Windows (which can only set user read and
+ # user write bits). Newer versions of Python use `os_helper.can_chmod()`
+ # instead of hardcoding Windows.
+ if mode is not None and sys.platform != 'win32':
+ got = stat.filemode(stat.S_IMODE(path.stat().st_mode))
+ self.assertEqual(got, mode)
+
+ if type is None and isinstance(name, str) and name.endswith('/'):
+ type = tarfile.DIRTYPE
+ if symlink_to is not None:
+ got = pathlib.Path(os.readlink(self.destdir / name))
+ expected = pathlib.Path(symlink_to)
+ # The symlink might be the same (textually) as what we expect,
+ # but some systems change the link to an equivalent path, so
+ # we fall back to samefile().
+ if expected != got:
+ self.assertTrue(got.samefile(expected))
+ elif type == tarfile.REGTYPE or type is None:
+ self.assertTrue(path.is_file())
+ elif type == tarfile.DIRTYPE:
+ self.assertTrue(path.is_dir())
+ elif type == tarfile.FIFOTYPE:
+ self.assertTrue(path.is_fifo())
+ else:
+ raise NotImplementedError(type)
+ for parent in path.parents:
+ self.expected_paths.discard(parent)
+
+ def expect_exception(self, exc_type, message_re='.'):
+ with self.assertRaisesRegex(exc_type, message_re):
+ if self.raised_exception is not None:
+ raise self.raised_exception
+ self.raised_exception = None
+
+ def test_benign_file(self):
+ with ArchiveMaker() as arc:
+ arc.add('benign.txt')
+ for filter in 'fully_trusted', 'tar', 'data':
+ with self.check_context(arc.open(), filter):
+ self.expect_file('benign.txt')
+
+ def test_absolute(self):
+ # Test handling a member with an absolute path
+ # Inspired by 'absolute1' in https://github.com/jwilk/traversal-archives
+ with ArchiveMaker() as arc:
+ arc.add(self.outerdir / 'escaped.evil')
+
+ with self.check_context(arc.open(), 'fully_trusted'):
+ self.expect_file('../escaped.evil')
+
+ for filter in 'tar', 'data':
+ with self.check_context(arc.open(), filter):
+ if str(self.outerdir).startswith('/'):
+ # We strip leading slashes, as e.g. GNU tar does
+ # (without --absolute-filenames).
+ outerdir_stripped = str(self.outerdir).lstrip('/')
+ self.expect_file(f'{outerdir_stripped}/escaped.evil')
+ else:
+ # On this system, absolute paths don't have leading
+ # slashes.
+ # So, there's nothing to strip. We refuse to unpack
+ # to an absolute path, nonetheless.
+ self.expect_exception(
+ tarfile.AbsolutePathError,
+ """['"].*escaped.evil['"] has an absolute path""")
+
+ def test_parent_symlink(self):
+ # Test interplaying symlinks
+ # Inspired by 'dirsymlink2a' in jwilk/traversal-archives
+ with ArchiveMaker() as arc:
+ arc.add('current', symlink_to='.')
+ arc.add('parent', symlink_to='current/..')
+ arc.add('parent/evil')
+
+ if support.can_symlink():
+ with self.check_context(arc.open(), 'fully_trusted'):
+ if self.raised_exception is not None:
+ # Windows will refuse to create a file that's a symlink to itself
+ # (and tarfile doesn't swallow that exception)
+ self.expect_exception(FileExistsError)
+ # The other cases will fail with this error too.
+ # Skip the rest of this test.
+ return
+ else:
+ self.expect_file('current', symlink_to='.')
+ self.expect_file('parent', symlink_to='current/..')
+ self.expect_file('../evil')
+
+ with self.check_context(arc.open(), 'tar'):
+ self.expect_exception(
+ tarfile.OutsideDestinationError,
+ """'parent/evil' would be extracted to ['"].*evil['"], """
+ + "which is outside the destination")
+
+ with self.check_context(arc.open(), 'data'):
+ self.expect_exception(
+ tarfile.LinkOutsideDestinationError,
+ """'parent' would link to ['"].*outerdir['"], """
+ + "which is outside the destination")
+
+ else:
+ # No symlink support. The symlinks are ignored.
+ with self.check_context(arc.open(), 'fully_trusted'):
+ self.expect_file('parent/evil')
+ with self.check_context(arc.open(), 'tar'):
+ self.expect_file('parent/evil')
+ with self.check_context(arc.open(), 'data'):
+ self.expect_file('parent/evil')
+
+ def test_parent_symlink2(self):
+ # Test interplaying symlinks
+ # Inspired by 'dirsymlink2b' in jwilk/traversal-archives
+ with ArchiveMaker() as arc:
+ arc.add('current', symlink_to='.')
+ arc.add('current/parent', symlink_to='..')
+ arc.add('parent/evil')
+
+ with self.check_context(arc.open(), 'fully_trusted'):
+ if support.can_symlink():
+ self.expect_file('current', symlink_to='.')
+ self.expect_file('parent', symlink_to='..')
+ self.expect_file('../evil')
+ else:
+ self.expect_file('current/')
+ self.expect_file('parent/evil')
+
+ with self.check_context(arc.open(), 'tar'):
+ if support.can_symlink():
+ self.expect_exception(
+ tarfile.OutsideDestinationError,
+ "'parent/evil' would be extracted to "
+ + """['"].*evil['"], which is outside """
+ + "the destination")
+ else:
+ self.expect_file('current/')
+ self.expect_file('parent/evil')
+
+ with self.check_context(arc.open(), 'data'):
+ self.expect_exception(
+ tarfile.LinkOutsideDestinationError,
+ """'current/parent' would link to ['"].*['"], """
+ + "which is outside the destination")
+
+ def test_absolute_symlink(self):
+ # Test symlink to an absolute path
+ # Inspired by 'dirsymlink' in jwilk/traversal-archives
+ with ArchiveMaker() as arc:
+ arc.add('parent', symlink_to=self.outerdir)
+ arc.add('parent/evil')
+
+ with self.check_context(arc.open(), 'fully_trusted'):
+ if support.can_symlink():
+ self.expect_file('parent', symlink_to=self.outerdir)
+ self.expect_file('../evil')
+ else:
+ self.expect_file('parent/evil')
+
+ with self.check_context(arc.open(), 'tar'):
+ if support.can_symlink():
+ self.expect_exception(
+ tarfile.OutsideDestinationError,
+ "'parent/evil' would be extracted to "
+ + """['"].*evil['"], which is outside """
+ + "the destination")
+ else:
+ self.expect_file('parent/evil')
+
+ with self.check_context(arc.open(), 'data'):
+ self.expect_exception(
+ tarfile.AbsoluteLinkError,
+ "'parent' is a symlink to an absolute path")
+
+ def test_sly_relative0(self):
+ # Inspired by 'relative0' in jwilk/traversal-archives
+ with ArchiveMaker() as arc:
+ arc.add('../moo', symlink_to='..//tmp/moo')
+
+ try:
+ with self.check_context(arc.open(), filter='fully_trusted'):
+ if support.can_symlink():
+ if isinstance(self.raised_exception, FileExistsError):
+ # XXX TarFile happens to fail creating a parent
+ # directory.
+ # This might be a bug, but fixing it would hurt
+ # security.
+ # Note that e.g. GNU `tar` rejects '..' components,
+ # so you could argue this is an invalid archive and we
+ # just raise an bad type of exception.
+ self.expect_exception(FileExistsError)
+ else:
+ self.expect_file('../moo', symlink_to='..//tmp/moo')
+ else:
+ # The symlink can't be extracted and is ignored
+ pass
+ except FileExistsError:
+ pass
+
+ for filter in 'tar', 'data':
+ with self.check_context(arc.open(), filter):
+ self.expect_exception(
+ tarfile.OutsideDestinationError,
+ "'../moo' would be extracted to "
+ + "'.*moo', which is outside "
+ + "the destination")
+
+ def test_sly_relative2(self):
+ # Inspired by 'relative2' in jwilk/traversal-archives
+ with ArchiveMaker() as arc:
+ arc.add('tmp/')
+ arc.add('tmp/../../moo', symlink_to='tmp/../..//tmp/moo')
+
+ with self.check_context(arc.open(), 'fully_trusted'):
+ self.expect_file('tmp', type=tarfile.DIRTYPE)
+ if support.can_symlink():
+ self.expect_file('../moo', symlink_to='tmp/../../tmp/moo')
+
+ for filter in 'tar', 'data':
+ with self.check_context(arc.open(), filter):
+ self.expect_exception(
+ tarfile.OutsideDestinationError,
+ "'tmp/../../moo' would be extracted to "
+ + """['"].*moo['"], which is outside the """
+ + "destination")
+
+ def test_modes(self):
+ # Test how file modes are extracted
+ # (Note that the modes are ignored on platforms without working chmod)
+ with ArchiveMaker() as arc:
+ arc.add('all_bits', mode='?rwsrwsrwt')
+ arc.add('perm_bits', mode='?rwxrwxrwx')
+ arc.add('exec_group_other', mode='?rw-rwxrwx')
+ arc.add('read_group_only', mode='?---r-----')
+ arc.add('no_bits', mode='?---------')
+ arc.add('dir/', mode='?---rwsrwt')
+
+ # On some systems, setting the sticky bit is a no-op.
+ # Check if that's the case.
+ tmp_filename = os.path.join(TEMPDIR, "tmp.file")
+ with open(tmp_filename, 'w'):
+ pass
+ os.chmod(tmp_filename, os.stat(tmp_filename).st_mode | stat.S_ISVTX)
+ have_sticky_files = (os.stat(tmp_filename).st_mode & stat.S_ISVTX)
+ os.unlink(tmp_filename)
+
+ os.mkdir(tmp_filename)
+ os.chmod(tmp_filename, os.stat(tmp_filename).st_mode | stat.S_ISVTX)
+ have_sticky_dirs = (os.stat(tmp_filename).st_mode & stat.S_ISVTX)
+ os.rmdir(tmp_filename)
+
+ with self.check_context(arc.open(), 'fully_trusted'):
+ if have_sticky_files:
+ self.expect_file('all_bits', mode='?rwsrwsrwt')
+ else:
+ self.expect_file('all_bits', mode='?rwsrwsrwx')
+ self.expect_file('perm_bits', mode='?rwxrwxrwx')
+ self.expect_file('exec_group_other', mode='?rw-rwxrwx')
+ self.expect_file('read_group_only', mode='?---r-----')
+ self.expect_file('no_bits', mode='?---------')
+ if have_sticky_dirs:
+ self.expect_file('dir/', mode='?---rwsrwt')
+ else:
+ self.expect_file('dir/', mode='?---rwsrwx')
+
+ with self.check_context(arc.open(), 'tar'):
+ self.expect_file('all_bits', mode='?rwxr-xr-x')
+ self.expect_file('perm_bits', mode='?rwxr-xr-x')
+ self.expect_file('exec_group_other', mode='?rw-r-xr-x')
+ self.expect_file('read_group_only', mode='?---r-----')
+ self.expect_file('no_bits', mode='?---------')
+ self.expect_file('dir/', mode='?---r-xr-x')
+
+ with self.check_context(arc.open(), 'data'):
+ normal_dir_mode = stat.filemode(stat.S_IMODE(
+ self.outerdir.stat().st_mode))
+ self.expect_file('all_bits', mode='?rwxr-xr-x')
+ self.expect_file('perm_bits', mode='?rwxr-xr-x')
+ self.expect_file('exec_group_other', mode='?rw-r--r--')
+ self.expect_file('read_group_only', mode='?rw-r-----')
+ self.expect_file('no_bits', mode='?rw-------')
+ self.expect_file('dir/', mode=normal_dir_mode)
+
+ def test_pipe(self):
+ # Test handling of a special file
+ with ArchiveMaker() as arc:
+ arc.add('foo', type=tarfile.FIFOTYPE)
+
+ for filter in 'fully_trusted', 'tar':
+ with self.check_context(arc.open(), filter):
+ if hasattr(os, 'mkfifo'):
+ self.expect_file('foo', type=tarfile.FIFOTYPE)
+ else:
+ # The pipe can't be extracted and is skipped.
+ pass
+
+ with self.check_context(arc.open(), 'data'):
+ self.expect_exception(
+ tarfile.SpecialFileError,
+ "'foo' is a special file")
+
+ def test_special_files(self):
+ # Creating device files is tricky. Instead of attempting that let's
+ # only check the filter result.
+ for special_type in tarfile.FIFOTYPE, tarfile.CHRTYPE, tarfile.BLKTYPE:
+ tarinfo = tarfile.TarInfo('foo')
+ tarinfo.type = special_type
+ trusted = tarfile.fully_trusted_filter(tarinfo, '')
+ self.assertIs(trusted, tarinfo)
+ tar = tarfile.tar_filter(tarinfo, '')
+ self.assertEqual(tar.type, special_type)
+ with self.assertRaises(tarfile.SpecialFileError) as cm:
+ tarfile.data_filter(tarinfo, '')
+ self.assertIsInstance(cm.exception.tarinfo, tarfile.TarInfo)
+ self.assertEqual(cm.exception.tarinfo.name, 'foo')
+
+ def test_fully_trusted_filter(self):
+ # The 'fully_trusted' filter returns the original TarInfo objects.
+ with tarfile.TarFile.open(tarname) as tar:
+ for tarinfo in tar.getmembers():
+ filtered = tarfile.fully_trusted_filter(tarinfo, '')
+ self.assertIs(filtered, tarinfo)
+
+ def test_tar_filter(self):
+ # The 'tar' filter returns TarInfo objects with the same name/type.
+ # (It can also fail for particularly "evil" input, but we don't have
+ # that in the test archive.)
+ with tarfile.TarFile.open(tarname) as tar:
+ for tarinfo in tar.getmembers():
+ filtered = tarfile.tar_filter(tarinfo, '')
+ self.assertIs(filtered.name, tarinfo.name)
+ self.assertIs(filtered.type, tarinfo.type)
+
+ def test_data_filter(self):
+ # The 'data' filter either raises, or returns TarInfo with the same
+ # name/type.
+ with tarfile.TarFile.open(tarname) as tar:
+ for tarinfo in tar.getmembers():
+ try:
+ filtered = tarfile.data_filter(tarinfo, '')
+ except tarfile.FilterError:
+ continue
+ self.assertIs(filtered.name, tarinfo.name)
+ self.assertIs(filtered.type, tarinfo.type)
+
+ def test_default_filter_warns_not(self):
+ """Ensure the default filter does not warn (like in 3.12)"""
+ with ArchiveMaker() as arc:
+ arc.add('foo')
+ with support.check_no_warnings(self):
+ with self.check_context(arc.open(), None):
+ self.expect_file('foo')
+
+ def test_change_default_filter_on_instance(self):
+ tar = tarfile.TarFile(tarname, 'r')
+ def strict_filter(tarinfo, path):
+ if tarinfo.name == 'ustar/regtype':
+ return tarinfo
+ else:
+ return None
+ tar.extraction_filter = strict_filter
+ with self.check_context(tar, None):
+ self.expect_file('ustar/regtype')
+
+ def test_change_default_filter_on_class(self):
+ def strict_filter(tarinfo, path):
+ if tarinfo.name == 'ustar/regtype':
+ return tarinfo
+ else:
+ return None
+ tar = tarfile.TarFile(tarname, 'r')
+ with support.swap_attr(tarfile.TarFile, 'extraction_filter',
+ staticmethod(strict_filter)):
+ with self.check_context(tar, None):
+ self.expect_file('ustar/regtype')
+
+ def test_change_default_filter_on_subclass(self):
+ class TarSubclass(tarfile.TarFile):
+ def extraction_filter(self, tarinfo, path):
+ if tarinfo.name == 'ustar/regtype':
+ return tarinfo
+ else:
+ return None
+
+ tar = TarSubclass(tarname, 'r')
+ with self.check_context(tar, None):
+ self.expect_file('ustar/regtype')
+
+ def test_change_default_filter_to_string(self):
+ tar = tarfile.TarFile(tarname, 'r')
+ tar.extraction_filter = 'data'
+ with self.check_context(tar, None):
+ self.expect_exception(TypeError)
+
+ def test_custom_filter(self):
+ def custom_filter(tarinfo, path):
+ self.assertIs(path, self.destdir)
+ if tarinfo.name == 'move_this':
+ return tarinfo.replace(name='moved')
+ if tarinfo.name == 'ignore_this':
+ return None
+ return tarinfo
+
+ with ArchiveMaker() as arc:
+ arc.add('move_this')
+ arc.add('ignore_this')
+ arc.add('keep')
+ with self.check_context(arc.open(), custom_filter):
+ self.expect_file('moved')
+ self.expect_file('keep')
+
+ def test_bad_filter_name(self):
+ with ArchiveMaker() as arc:
+ arc.add('foo')
+ with self.check_context(arc.open(), 'bad filter name'):
+ self.expect_exception(ValueError)
+
+ def test_stateful_filter(self):
+ # Stateful filters should be possible.
+ # (This doesn't really test tarfile. Rather, it demonstrates
+ # that third parties can implement a stateful filter.)
+ class StatefulFilter:
+ def __enter__(self):
+ self.num_files_processed = 0
+ return self
+
+ def __call__(self, tarinfo, path):
+ try:
+ tarinfo = tarfile.data_filter(tarinfo, path)
+ except tarfile.FilterError:
+ return None
+ self.num_files_processed += 1
+ return tarinfo
+
+ def __exit__(self, *exc_info):
+ self.done = True
+
+ with ArchiveMaker() as arc:
+ arc.add('good')
+ arc.add('bad', symlink_to='/')
+ arc.add('good')
+ with StatefulFilter() as custom_filter:
+ with self.check_context(arc.open(), custom_filter):
+ self.expect_file('good')
+ self.assertEqual(custom_filter.num_files_processed, 2)
+ self.assertEqual(custom_filter.done, True)
+
+ def test_errorlevel(self):
+ def extracterror_filter(tarinfo, path):
+ raise tarfile.ExtractError('failed with ExtractError')
+ def filtererror_filter(tarinfo, path):
+ raise tarfile.FilterError('failed with FilterError')
+ def oserror_filter(tarinfo, path):
+ raise OSError('failed with OSError')
+ def tarerror_filter(tarinfo, path):
+ raise tarfile.TarError('failed with base TarError')
+ def valueerror_filter(tarinfo, path):
+ raise ValueError('failed with ValueError')
+
+ with ArchiveMaker() as arc:
+ arc.add('file')
+
+ # If errorlevel is 0, errors affected by errorlevel are ignored
+
+ with self.check_context(arc.open(errorlevel=0), extracterror_filter):
+ self.expect_file('file')
+
+ with self.check_context(arc.open(errorlevel=0), filtererror_filter):
+ self.expect_file('file')
+
+ with self.check_context(arc.open(errorlevel=0), oserror_filter):
+ self.expect_file('file')
+
+ with self.check_context(arc.open(errorlevel=0), tarerror_filter):
+ self.expect_exception(tarfile.TarError)
+
+ with self.check_context(arc.open(errorlevel=0), valueerror_filter):
+ self.expect_exception(ValueError)
+
+ # If 1, all fatal errors are raised
+
+ with self.check_context(arc.open(errorlevel=1), extracterror_filter):
+ self.expect_file('file')
+
+ with self.check_context(arc.open(errorlevel=1), filtererror_filter):
+ self.expect_exception(tarfile.FilterError)
+
+ with self.check_context(arc.open(errorlevel=1), oserror_filter):
+ self.expect_exception(OSError)
+
+ with self.check_context(arc.open(errorlevel=1), tarerror_filter):
+ self.expect_exception(tarfile.TarError)
+
+ with self.check_context(arc.open(errorlevel=1), valueerror_filter):
+ self.expect_exception(ValueError)
+
+ # If 2, all non-fatal errors are raised as well.
+
+ with self.check_context(arc.open(errorlevel=2), extracterror_filter):
+ self.expect_exception(tarfile.ExtractError)
+
+ with self.check_context(arc.open(errorlevel=2), filtererror_filter):
+ self.expect_exception(tarfile.FilterError)
+
+ with self.check_context(arc.open(errorlevel=2), oserror_filter):
+ self.expect_exception(OSError)
+
+ with self.check_context(arc.open(errorlevel=2), tarerror_filter):
+ self.expect_exception(tarfile.TarError)
+
+ with self.check_context(arc.open(errorlevel=2), valueerror_filter):
+ self.expect_exception(ValueError)
+
+ # We only handle ExtractionError, FilterError & OSError specially.
+
+ with self.check_context(arc.open(errorlevel='boo!'), filtererror_filter):
+ self.expect_exception(TypeError) # errorlevel is not int
+
+
def setUpModule():
support.unlink(TEMPDIR)
os.makedirs(TEMPDIR)
diff --git a/Misc/NEWS.d/next/Library/2023-03-23-15-24-38.gh-issue-102953.YR4KaK.rst b/Misc/NEWS.d/next/Library/2023-03-23-15-24-38.gh-issue-102953.YR4KaK.rst
new file mode 100644
index 000000000000..48a105a4a17b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2023-03-23-15-24-38.gh-issue-102953.YR4KaK.rst
@@ -0,0 +1,4 @@
+The extraction methods in :mod:`tarfile`, and :func:`shutil.unpack_archive`,
+have a new a *filter* argument that allows limiting tar features than may be
+surprising or dangerous, such as creating files outside the destination
+directory. See :ref:`tarfile-extraction-filter` for details.
More information about the Python-checkins
mailing list