Bug 1774471
| Summary: | Python os.urandom() is not FIPS compliant | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Product: | Red Hat Enterprise Linux 8 | Reporter: | Christian Heimes <cheimes> | ||||||
| Component: | python3 | Assignee: | Python Maintainers <python-maint> | ||||||
| Status: | CLOSED ERRATA | QA Contact: | Lukáš Zachar <lzachar> | ||||||
| Severity: | high | Docs Contact: | |||||||
| Priority: | unspecified | ||||||||
| Version: | 8.2 | CC: | abokovoy, cheimes, cstratak, jkejda, mkosek, pviktori, ssorce, torsava | ||||||
| Target Milestone: | rc | Flags: | cheimes:
needinfo-
|
||||||
| Target Release: | 8.2 | ||||||||
| Hardware: | Unspecified | ||||||||
| OS: | Unspecified | ||||||||
| Whiteboard: | |||||||||
| Fixed In Version: | python3-3.6.8-23.el8 | Doc Type: | No Doc Update | ||||||
| Doc Text: | Story Points: | --- | |||||||
| Clone Of: | Environment: | ||||||||
| Last Closed: | 2020-04-28 16:08:30 UTC | Type: | Bug | ||||||
| Regression: | --- | Mount Type: | --- | ||||||
| Documentation: | --- | CRM: | |||||||
| Verified Versions: | Category: | --- | |||||||
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |||||||
| Cloudforms Team: | --- | Target Upstream Version: | |||||||
| Embargoed: | |||||||||
| Bug Depends On: | |||||||||
| Bug Blocks: | 1760850 | ||||||||
| Attachments: |
|
||||||||
Created attachment 1638086 [details]
Experimental patch for Python master
The patch adds RAND_bytes() as preferred RNG source for Python.
A patched Python calls getrandom() three times when OpenSSL initializes its DRBG. There may be more calls under FIPS. os.urandom() does not call getrandom() any more.
$ strace -e getrandom ./python -c "import os; os.urandom(8); os.urandom(8); os.urandom(8)"
getrandom("...", 16, 0) = 16
getrandom("...", 16, 0) = 16
getrandom("...", 16, 0) = 16
Created attachment 1639525 [details] Updated FIPS getrandom patch on top of Petr's FIPS branch https://github.com/encukou/cpython/compare/fips...tiran:fips_getrandom?expand=1 Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHSA-2020:1764 |
Description of problem: Python's internal CSPRNG for hash randomization and os.urandom() use the Kernel DRBG via the getrandom() syscall. The Kernel RNG is not (yet) FIPS compliant. os.urandom() is the preferred source for cryptographically secure random data. It is used a lot, amongst others by 389-DS/RHDS, IPA/IdM, and Dogtag/RHCS. It would take too much effort the modify all Python libraries and applications to use a FIPS compliant RNG. Instead Python should be modified to handle FIPS compliance internally. Version-Release number of selected component (if applicable): python3-3.6.8-22.el8 How reproducible: always Steps to Reproduce: 1. strace -egetrandom python3 -c "import os; os.urandom(8)" Actual results: getrandom("...", 24, GRND_NONBLOCK) = 24 getrandom("...", 8, 0) = 8 Expected results: getrandom syscall is not used by Python directly. Additional info: There is an ongoing effort to make the Kernel's DRBG FIPS compliant. However it is not clear if the goal can be archived in time for RHEL 8.2. Python can use OpenSSL's DRBG through RAND_bytes() API. The DRBG in OpenSSL 1.1.1 is fork-safe.