Bug 2218873 - sos: Python tarfile extraction needs change to avoid a warning (CVE-2007-4559 mitigation)
Summary: sos: Python tarfile extraction needs change to avoid a warning (CVE-2007-4559...
Keywords:
Status: POST
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: sos
Version: 8.9
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Pavel Moravec
QA Contact: Supportability QE
URL:
Whiteboard:
: 2218238 (view as bug list)
Depends On:
Blocks: CVE-2007-4559
TreeView+ depends on / blocked
 
Reported: 2023-06-30 11:18 UTC by Petr Viktorin
Modified: 2023-08-15 17:09 UTC (History)
7 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed:
Type: Bug
Target Upstream Version:
Embargoed:


Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Github sosreport sos issues 3319 0 None open Fix PEP706 warning 2023-07-26 13:59:59 UTC
Red Hat Issue Tracker RHELPLAN-161320 0 None None None 2023-06-30 11:19:27 UTC

Description Petr Viktorin 2023-06-30 11:18:00 UTC
Hello,
In RHEL 9.3 and 8.9, we're planning to fix the long-standing CVE-2007-4559: Python's `tarfile` module makes it too easy to extract tarballs in an unsafe way.
Unfortunately, for the CVE to be considered fixed, this needs a behavior change. (If you don't think this is the case, let's bring it up with the security team.)
Upstream, Python will emit deprecation warnings for 2 releases, but in RHEL we change the behavior now, emit warnings, and provide ways for customers to restore earlier behavior.
To avoid the warning, software shipped by Red Hat will need a change.

For more details see upstream PEP 706: https://peps.python.org/pep-0706
and the Red Hat knowledge base draft: https://access.redhat.com/articles/7004769

---

In /usr/lib/python3.6/site-packages/sos/cleaner/archives/__init__.py, sos calls `archive.extractall(path)`. The call will emit a warning by default. To prevent that, add something like this before the call:

archive.extraction_filter = getattr(tarfile, 'data_filter',
                                       (lambda member, path: member))

This is compatible with unpatched versions of Python. If you only build for RHEL8.9+, instead add an argument to the call:
`archive.extractall(path, filter='data')`.

The 'data' filter above attempts a "safe" extraction, intended for pure data archives. For example:
- prevents extracting outside the target directory, and to absolute paths (by raising an exception)
- prevents symlinks pointing outside the target directory, and to absolute paths
- adjusts permissions (for the owner, only the executable bit is honored)
See PEP 706 for details: https://peps.python.org/pep-0706/#filters

If you trust the tarball, use `'fully_trusted_filter'` (or `filter='fully_trusted'`) instead. That will preserve the existing behavior.

---

Let me know if you have any questions!

Comment 1 Pavel Moravec 2023-07-26 14:00:26 UTC
*** Bug 2218238 has been marked as a duplicate of this bug. ***


Note You need to log in before you can comment on or make changes to this bug.