Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Fri, 18 Dec 2015 00:07:19 +0100
From: Jann Horn <>
To: John Johansen <>
Subject: Re: CVE Request: Linux kernel: privilege escalation in user

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
> 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)

Powered by blists - more mailing lists

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.