Hi, It seem like we should block (at least) this combination. On 3.9, this exploit works once uidmapping is added.
http://www.openwall.com/lists/oss-security/2013/03/13/10 -Kees ----- Forwarded message from Sebastian Krahmer <krah...@suse.de> ----- Date: Wed, 13 Mar 2013 16:39:56 +0100 From: Sebastian Krahmer <krah...@suse.de> To: oss-secur...@lists.openwall.com Subject: [oss-security] CLONE_NEWUSER|CLONE_FS root exploit Envelope-To: k...@outflux.net Hi, Seems like CLONE_NEWUSER|CLONE_FS might be a forbidden combination. During evaluating the new user namespace thingie, it turned out that its trivially exploitable to get a (real) uid 0, as demonstrated here: http://stealth.openwall.net/xSports/clown-newuser.c The trick is to setup a chroot in your CLONE_NEWUSER, but also affecting the parent, which is running in the init_user_ns, but with the chroot shared. Then its trivial to get a rootshell from that. Tested on a openSUSE12.1 with a custom build 3.8.2 (x86_64). I hope I didnt make anything wrong, mixing up the UIDs, or disabled important checks during kernel build on my test system. ;) regards, Sebastian -- ~ perl self.pl ~ $_='print"\$_=\47$_\47;eval"';eval ~ krah...@suse.de - SuSE Security Team ----- End forwarded message ----- -- Kees Cook Chrome OS Security -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/