Bug 1539977

Summary:	CVE-2017-18078 systemd: Unsafe handling of hard links allowing privilege escalation [fedora-all]
Product:	[Fedora] Fedora	Reporter:	Doran Moppert <dmoppert>
Component:	systemd	Assignee:	systemd-maint
Status:	CLOSED WONTFIX	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	27	CC:	lnykryn, msekleta, ssahani, s, systemd-maint, zbyszek
Target Milestone:	---	Keywords:	Security, SecurityTracking
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Release Note
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2018-07-04 09:47:47 UTC	Type:	---
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:	1539758

Description Doran Moppert 2018-01-30 00:37:36 UTC

This is an automatically created tracking bug!  It was created to ensure
that one or more security vulnerabilities are fixed in affected versions
of fedora-all.

For comments that are specific to the vulnerability please use bugs filed
against the "Security Response" product referenced in the "Blocks" field.

For more information see:
http://fedoraproject.org/wiki/Security/TrackingBugs

When submitting as an update, use the fedpkg template provided in the next
comment(s).  This will include the bug IDs of this tracking bug as well as
the relevant top-level CVE bugs.

Please also mention the CVE IDs being fixed in the RPM changelog and the
fedpkg commit message.

NOTE: this issue affects multiple supported versions of Fedora. While only
one tracking bug has been filed, please correct all affected versions at
the same time.  If you need to fix the versions independent of each other,
you may clone this bug as appropriate.

Comment 1 Doran Moppert 2018-01-30 00:37:41 UTC

Use the following template to for the 'fedpkg update' request to submit an
update for this issue as it contains the top-level parent bug(s) as well as
this tracking bug.  This will ensure that all associated bugs get updated
when new packages are pushed to stable.

=====

# bugfix, security, enhancement, newpackage (required)
type=security

# testing, stable
request=testing

# Bug numbers: 1234,9876
bugs=1539758,1539977

# Description of your update
notes=Security fix for [PUT CVEs HERE]

# Enable request automation based on the stable/unstable karma thresholds
autokarma=True
stable_karma=3
unstable_karma=-3

# Automatically close bugs when this marked as stable
close_bugs=True

# Suggest that users restart after update
suggest_reboot=False

======

Additionally, you may opt to use the bodhi web interface to submit updates:

https://bodhi.fedoraproject.org/updates/new

Comment 2 Zbigniew Jędrzejewski-Szmek 2018-07-04 09:47:47 UTC

I'll provide the same resolution as RHEL:
> Red Hat Product Security has rated this issue as having Moderate security
> impact. This issue is not exploitable in the default configuration […]
>
> Mitigation:
> 
> This flaw, and many others like it, is mitigated by enabling hardlink and
> symlink protections. These protections are enabled by default in [Fedora]
> and this vulnerability will only be exploitable if disabled.
> 
> To ensure your system is protected, check that `fs.protected_hardlinks` is
> enabled as in the following example:
> 
>   # sysctl fs.protected_hardlinks
>   fs.protected_hardlinks = 1