Date: Fri, 18 Dec 2015 00:07:19 +0100 From: Jann Horn <jann@...jh.net> To: John Johansen <john.johansen@...onical.com> Cc: oss-security@...ts.openwall.com Subject: Re: CVE Request: Linux kernel: privilege escalation in user namespaces On Thu, Dec 17, 2015 at 02:39:58PM -0800, John Johansen wrote: > I haven't seen CVE request for this one yet so, > > Jann Horn reported a privilege escalation in user namespaces to the > lkml mailing list > > https://lkml.org/lkml/2015/12/12/259 > > if a root-owned process wants to enter a user > namespace for some reason without knowing who owns it and > therefore can't change to the namespace owner's uid and gid > before entering, as soon as it has entered the namespace, > the namespace owner can attach to it via ptrace and thereby > gain access to its uid and gid. I'm not sure whether this is CVE-worthy - the user_namespaces manpage says "the process has full privileges for operations inside the user namespace, but is unprivileged for operations outside the namespace". ptrace()ing a process in the namespace can reasonably be considered an "operation inside the user namespace", and therefore the manpage kinda implies the old behavior. (Yes, more detailed documentation would be nicer, I might submit man-pages patches once my patches are in a kernel release.) In my opinion, this patch is somewhere between hardening and a security feature, but I wouldn't really call it a vuln fix. Download attachment "signature.asc" of type "application/pgp-signature" (820 bytes)
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