Bug 1905672 (CVE-2020-29480)

Summary:	CVE-2020-29480 xen: xenstore watch notifications lacking permission checks (XSA-115)
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED UPSTREAM	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	jforbes, m.a.young, robinlee.sysu, security-response-team
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-12-15 22:20:09 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:	1908091
Bug Blocks:	1903644

Description Guilherme de Almeida Suckevicz 2020-12-08 19:31:57 UTC

Neither xenstore implementation does any permissions checks when
reporting a xenstore watch event.

A guest administrator can watch the root xenstored node, which will
cause notifications for every created, modified and deleted key.

A guest administrator can also use the special watches, which will
cause a notification every time a domain is created and destroyed.

Data may include:
 - number, type and domids of other VMs
 - existence and domids of driver domains
 - numbers of virtual interfaces, block devices, vcpus
 - existence of virtual framebuffers and their backend style (eg,
   existence of VNC service)
 - Xen VM UUIDs for other domains
 - timing information about domain creation and device setup
 - some hints at the backend provisioning of VMs and their devices

The watch events do not contain values stored in xenstore, only key
names.

Comment 1 Guilherme de Almeida Suckevicz 2020-12-15 20:03:19 UTC

External References:

https://www.openwall.com/lists/oss-security/2020/12/15/2

Comment 2 Guilherme de Almeida Suckevicz 2020-12-15 20:03:33 UTC

Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1908091]

Comment 3 Product Security DevOps Team 2020-12-15 22:20:09 UTC

This CVE Bugzilla entry is for community support informational purposes only as it does not affect a package in a commercially supported Red Hat product. Refer to the dependent bugs for status of those individual community products.