============================================================================= FreeBSD-SA-13:12.ifioctl Security Advisory The FreeBSD Project Topic: Insufficient credential checks in network ioctl(2) Category: core Module: sys_netinet6 sys_netatm Announced: 2013-09-10 Credits: Loganaden Velvindron Gleb Smirnoff Affects: All supported versions of FreeBSD. Corrected: 2013-09-10 10:07:21 UTC (stable/9, 9.2-STABLE) 2013-09-10 10:08:20 UTC (releng/9.2, 9.2-RC1-p2) 2013-09-10 10:08:20 UTC (releng/9.2, 9.2-RC2-p2) 2013-09-10 10:08:20 UTC (releng/9.2, 9.2-RC3-p1) 2013-09-10 10:15:33 UTC (releng/9.1, 9.1-RELEASE-p7) 2013-09-10 10:12:09 UTC (stable/8, 8.4-STABLE) 2013-09-10 10:14:19 UTC (releng/8.4, 8.4-RELEASE-p4) 2013-09-10 10:13:14 UTC (releng/8.3, 8.3-RELEASE-p11) CVE Name: CVE-2013-5691 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit <URL:http://security.FreeBSD.org/>. I. Background The ioctl(2) system call allows an application to perform device- or protocol-specific operations through a file or socket descriptor associated with a specific device or protocol. The SIOCSIFADDR, SIOCSIFBRDADDR, SIOCSIFDSTADDR and SIOCSIFNETMASK ioctl requests are used to associate a network address, broadcast address, destination address (for point-to-point interfaces) or netmask with an interface. They operate on the assumption that each interface only has one address per protocol, and are therefore of limited use for IPv4, where interfaces may have more than one address. They were never implemented for IPv6, where interfaces nearly always have at least two, and in many cases three, addresses; nor were they ever implemented for ATM. II. Problem Description As is commonly the case, the IPv6 and ATM network layer ioctl request handlers are written in such a way that an unrecognized request is passed on unmodified to the link layer, which will either handle it or return an error code. Network interface drivers, however, assume that the SIOCSIFADDR, SIOCSIFBRDADDR, SIOCSIFDSTADDR and SIOCSIFNETMASK requests have been handled at the network layer, and therefore do not perform input validation or verify the caller's credentials. Typical link-layer actions for these requests may include marking the interface as "up" and resetting the underlying hardware. III. Impact An unprivileged user with the ability to run arbitrary code can cause any network interface in the system to perform the link layer actions associated with a SIOCSIFADDR, SIOCSIFBRDADDR, SIOCSIFDSTADDR or SIOCSIFNETMASK ioctl request; or trigger a kernel panic by passing a specially crafted address structure which causes a network interface driver to dereference an invalid pointer. Although this has not been confirmed, the possibility that an attacker may be able to execute arbitrary code in kernel context can not be ruled out. IV. Workaround No workaround is available. V. Solution Perform one of the following: 1) Upgrade your vulnerable system to a supported FreeBSD stable or release / security branch (releng) dated after the correction date. 2) To update your vulnerable system via a source code patch: The following patches have been verified to apply to the applicable FreeBSD release branches. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. # fetch http://security.FreeBSD.org/patches/SA-13:12/ifioctl.patch # fetch http://security.FreeBSD.org/patches/SA-13:12/ifioctl.patch.asc # gpg --verify ifioctl.patch.asc b) Apply the patch. # cd /usr/src # patch < /path/to/patch c) Recompile your kernel as described in <URL:http://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the system. 3) To update your vulnerable system via a binary patch: Systems running a RELEASE version of FreeBSD on the i386 or amd64 platforms can be updated via the freebsd-update(8) utility: # freebsd-update fetch # freebsd-update install VI. Correction details The following list contains the correction revision numbers for each affected branch. Branch/path Revision - ------------------------------------------------------------------------- stable/8/ r255445 releng/8.3/ r255446 releng/8.4/ r255447 stable/9/ r255443 releng/9.1/ r255448 releng/9.2/ r255444 - ------------------------------------------------------------------------- To see which files were modified by a particular revision, run the following command, replacing NNNNNN with the revision number, on a machine with Subversion installed: # svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base Or visit the following URL, replacing NNNNNN with the revision number: <URL:http://svnweb.freebsd.org/base?view=revision&revision=NNNNNN> VII. References <URL:http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-5691> The latest revision of this advisory is available at <URL:http://security.FreeBSD.org/advisories/FreeBSD-SA-13:12.ifioctl.asc>
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