Bug 859060 (CVE-2013-4392)

Summary: CVE-2013-4392 systemd: TOCTOU race condition when updating file permissions and SELinux security contexts
Product: [Other] Security Response Reporter: Jan Lieskovsky <jlieskov>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: carnil, fweimer, jlieskov, jrusnack, jsegitz, lnykryn, lpoetter, meissner, security-response-team, systemd-maint-list, systemd-maint, xaionaro, zbyszek
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard: impact=moderate,public=20130923,reported=20120919,source=redhat,cvss2=3.3/AV:L/AC:M/Au:N/C:P/I:P/A:N,fedora-all/systemd=affected,rhel-7/systemd=wontfix,cwe=CWE-367
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2015-11-02 23:57:01 EST Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---
Bug Depends On: 858766, 858760, 1043749    
Bug Blocks: 859151    

Description Jan Lieskovsky 2012-09-20 09:35:54 EDT
A TOCTOU (time-of-check time-of-use) race condition was found in the way systemd, a system and service manager, used to update file permissions and SELinux security contexts. A local attacker could use this flaw to conduct symbolic link attacks possibly leading to their ability to modify permissions / security context of a path different than originally intended / requested.

Issue found by Florian Weimer, Red Hat Product Security Team
Comment 1 Jan Lieskovsky 2012-09-20 09:37:33 EDT
This issue affects the versions of the systemd package, as shipped with Fedora release of 16 and 17.
Comment 3 Vincent Danen 2013-10-01 18:52:13 EDT

This issue was discovered by Florian Weimer of the Red Hat Product Security Team.
Comment 4 Vincent Danen 2013-10-01 18:52:54 EDT
This was assigned CVE-2013-4392:

Comment 5 Marcus Meissner 2013-11-22 06:00:34 EST
Do you know at which place this happened? I have a hard time pinpointing it down. ;)
Comment 11 Florian Weimer 2014-03-24 05:05:50 EDT
This is currently blocked by the need for new system calls (or making existing system calls work with O_PATH):


We need to open files to check their hard link count and make sure that is not greater than 1, so that we do not improperly relabel a file that is visible elsewhere in the file system.  Without O_PATH, the open operation can have side effects, so we would introduce another type of security bug.

Addressing this would also fix the other issue (lsetfilecon is called with absolute paths, which does not prevent symbol link resolution on non-final path components), but this issue could be fixed separate if desired.
Comment 12 Huzaifa S. Sidhpurwala 2014-03-24 05:35:02 EDT
This issue affects the version of systemd as shipped with Fedora 19 and Fedora 20 and is waiting on upstream fix as indicated by comment #11.