Bug 2207691

Summary:	python3-lib389: Python tarfile extraction needs change to avoid a warning (CVE-2007-4559 mitigation)
Product:	Red Hat Enterprise Linux 9	Reporter:	Petr Viktorin <pviktori>
Component:	389-ds-base	Assignee:	LDAP Maintainers <idm-ds-dev-bugs>
Status:	VERIFIED ---	QA Contact:	LDAP QA Team <idm-ds-qe-bugs>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	9.3	CC:	bsmejkal, idm-ds-dev-bugs, mreynolds, vashirov
Target Milestone:	rc	Keywords:	Triaged
Target Release:	9.3
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	sync-to-jira
Fixed In Version:	389-ds-base-2.3.6-2.el9	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
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Clones:	2218235 (view as bug list)		Environment:
Last Closed:		Type:	Bug
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Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
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Embargoed:
Bug Depends On:	263261
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Description Petr Viktorin 2023-05-16 14:29:06 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 __init__.py and tools.py in /usr/lib/python3.9/site-packages/lib389/, lib389 calls `tar.extract()`. The calls will emit a warning by default, and tar features deemed too dangerous for general use will even be blocked by default.

It seems that this is a backup recovery, and you trust the archive to not be malicious. In that case, add the following after the `tar = tarfile.open(backup_file)`:

    # The archive is fully trusted, override warnings and "safe" defaults
    # see https://docs.python.org/3.12/library/tarfile.html#supporting-older-python-versions
    tar.extraction_filter = (lambda member, path: member)

This will restore previous behaviour, and it's a no-op on earlier Python versions.

---

Let me know if you have any questions!

Comment 1 Viktor Ashirov 2023-08-14 15:48:12 UTC

Builds tested: 
389-ds-base-2.3.6-2.el9.x86_64
python3-lib389-2.3.6-2.el9.noarch

A filter was added:
$ grep -inr -A1  tarfile.open /usr/lib/python3.9/site-packages/lib389
/usr/lib/python3.9/site-packages/lib389/__init__.py:1380:        tar = tarfile.open(backup_file, "w:gz")
/usr/lib/python3.9/site-packages/lib389/__init__.py-1381-        tar.extraction_filter = (lambda member, path: member)
--
/usr/lib/python3.9/site-packages/lib389/__init__.py:1454:        tar = tarfile.open(backup_file)
/usr/lib/python3.9/site-packages/lib389/__init__.py-1455-        tar.extraction_filter = (lambda member, path: member)
--
/usr/lib/python3.9/site-packages/lib389/tools.py:303:        tar = tarfile.open(backup_file, "w:gz")
/usr/lib/python3.9/site-packages/lib389/tools.py-304-        tar.extraction_filter = (lambda member, path: member)
--
/usr/lib/python3.9/site-packages/lib389/tools.py:362:        tar = tarfile.open(backup_file)
/usr/lib/python3.9/site-packages/lib389/tools.py-363-        tar.extraction_filter = (lambda member, path: member)

Moreover, this code is in functions that are not used by any other code in lib389:
lib389.backupFS
lib389.restoreFS
lib389.tools.instanceBackupFS
lib389.tools.instanceRestoreFS

These were implemented to speed up testing, but since then were replaced by pytest fixtures. They will be removed in https://github.com/389ds/389-ds-base/issues/5875

Comment 4 bsmejkal 2023-08-17 08:28:53 UTC

As per comment #c1 marking as VERIFIED.